Summer Training Report at TATA MOTORS

8/8/2019 Summer Training Report at TATA MOTORS

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PROJECT REPORT

ON SUMMER TRAINING INTATA MOTORS, LUCKNOW

SUBMITTED BYSUDHANSHU

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Mechanical EngineeringDepartment SRMS

CET,BAREILLY

Under the Guidance of

Mr.TANUJ SONKERCX-CWP

CONTENTS

Declaration

Acknowledgement

TATA MOTORS- An IntroductionTATA Journey-Year by year

Organisation Structure

TATA MOTORS-Lucknow Plant

What is a CROWN wheel

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Gears Manufacturing and its uses

Detailed Study of GLEASON NO.610

Productivity Improvement

My Role

Overview

DECLARATION

I hereby declare that the project work entitled: 1.PRODUCTIVITY IMPROVEMENT OF GLEASON

NO.610 HYPOID GEAR MACHINE is an authenticrecord of my own work carried out at TATA MOTORS,(CX-CWP) , LUCKNOW as

requirements of four week summer project , under theguidance ofMR.TANUJ SONKER

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SUDHANSHU B.TECH.2nd year

Certified that the above statement made by thestudent is correct to the best of our knowledge and

belief.

Mr.TANUJ SONKER Ms.JASNEET RAKHRACX-CWP MANAGER,HR

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ACKNOWLEDGEMENT

Industrial training is a crucial period in engineeringcurriculum since it exposes a student to the real worldwhich he or she is going to enter after the completionof the graduation. This is the period during which an

engineer actually becomes an engineer by gaining theIndustrial experience. I am very thankful to God whohas given me the opportunity to get training in TATA

MOTORS, LUCKNOW one of the most renowned

organization of India. I would like to express my deepgratitude to my Project Head MR. TANUJ SONKER,CX-CWP for having provided me with the wonderful &

conductive environment to work in and realize whatreally industry is, he has been ever helpful and

supportive. Last but not the least I would like to thankMS. JASNEET RAKHRA (Manager HR) for providing

me the opportunity to add a new dimension to my

personality. I will remain indebted to her for hergenerous ways of dealing with industrial trainees.

SUDHANSHU,B.Tech. 2nd year,SRMS CET,Bareilly

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TATA MOTORS

Tata Motors is a part of theTata Group manages itsshare-holding throughTata Sons. The company wasestablished in 1935 as a locomotive manufacturing unitand later expanded its operations to commercialvehicle sector in 1954 after forming a joint venture withDaimler-Benz AG of Germany. Despite the success ofits commercial vehicles, Tata realized his company hadto diversify and he began to look at other products.Based on consumer demand, he decided that building asmall car would be the most practical new venture. Soin 1998 it launchedTata Indica, India's first fullyindigenous passenger car. Designed to be inexpensiveand simple to build and maintain, the Indica became ahit in the Indian market. It was also exported to Europe,especially the UK and Italy. In 2004 it acquired TataDaewoo Commercial Vehicle, and in late 2005 itacquired 21% ofAragoneseHispano Carrocera giving itcontrolling rights of the company. It has formed a jointventure with Marcopolo of Brazil, and introduced low-floor buses in the Indian Market. Recently, it hasacquired British Jaguar Land Rover (JLR), which includesthe Daimler and Lanchester brand names.

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TATA JOURNEY YEAR BY YEAR:

1868: Jamsetji Nusserwanji Tata starts a privatetrading firm, laying the foundation of the TATAgroup.

1874: The Central India Spinning, Weaving andManufacturing Company is set up, marking theGroup's entry into textiles.

1902: The Indian Hotels Company is incorporatedto set up the Taj Mahal Palace and Tower, India's

first luxury hotel, which opened in 1903. 1907: The Tata Iron and Steel Company (now Tata

Steel) is established to set up India's first iron andsteel plant in Jamshedpur. The plant startedproduction in 1912.

1910: The first of the three Tata ElectricCompanies, The Tata Hydro-Electric Power SupplyCompany, (now Tata Power) is set up.

1911: The Indian Institute of Science is establishedin Bangalore to serve as a centre for advancedlearning.

1912: Tata Steel introduces eight-hour workingdays, well before such a system was implementedby law in much of the West.

1917: The Tatas enter the consumer goodsindustry, with the Tata Oil Mills Company being

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established to make soaps, detergents and cookingoils.

1932: Tata Airlines, a division of Tata Sons, isestablished, opening up the aviation sector inIndia.

1939:Tata Chemicals, now the largest producer ofsoda ash in the country, is established.

1945: Tata Engineering and Locomotive Company(renamed Tata Motors in 2003) is established tomanufacture locomotive and engineering products.

Tata Industries is created for the promotion anddevelopment of hi-tech industries.

1952: Jawaharlal Nehru, India's first PrimeMinister, requests the Group to manufacturecosmetics in India, leading to the setting up ofLakme.

1954: India's major marketing, engineering andmanufacturing organization, Voltas, is established.

1962: Tata Finlay (now Tata Tea), one of thelargest tea producers, is established. Tata Exportsis established. Today the company, renamed TataInternational, is one of the leading export houses inIndia.

1968: Tata Consultancy Services (TCS), India'sfirst software services company, is established as adivision of Tata Sons.

1970: Tata McGraw-Hill Publishing Company iscreated to publish educational and technical books.

Tata Economic Consultancy Services is set up toprovide services in the field of industrial,marketing, statistical and techno-economicresearch and consultancy.

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1984: Titan Industries - a joint venture betweenthe Tata Group and the Tamil Nadu IndustrialDevelopment Corporation (TIDCO) - is set up tomanufacture watches.

1991:Tata Motors rolls out its millionth vehicle.(The two-million mark was reached in 1998 and thethird million in 2003.)

1995: Tata Quality Management Servicesinstitutes the JRD QV Award, modelled on theMalcolm Baldrige National Quality Value Award ofthe United States, laying the foundation of the TataBusiness Excellence Model.

1996: Tata Tele services (TTSL) is established tospearhead the Group's foray into the telecomsector.

1998: Tata Indica - India's first indigenouslydesigned and manufactured car is launched by

Tata Motors, spearheading the Group's entry intothe passenger car segment.

1999: The new Tata Group corporate mark andlogo are launched.

2000: Tata Tea acquires the Tetley Group, UK. Thisis the first major acquisition of an internationalbrand by an Indian business group.

2001: Tata-AIG - a joint venture between the TataGroup and American International Group Inc (AIG) -marks the Tata re-entry into insurance. (TheGroup's insurance company, New India Assurance,was nationalized in 1956). The Tata GroupExecutive Office (GEO) is set up to design andimplement change in the Tata Group and toprovide long-term direction.

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2002: The Tata Group acquires a controlling stakein VSNL, India's leading internationaltelecommunications service provider TataConsultancy Services (TCS) becomes the firstIndian software company to cross one billiondollars in revenues. Titan launches Edge, theslimmest watch in the world. Idea Cellular, thecellular service born of a tie-up involving the TataGroup, the Birla Group and AT&T, is launched. TataIndicom, the umbrella brand for telecom servicesfrom the Tata Tele services stable, startsoperations.

2003: Tata Motors launches City Rover Indicasfashioned for the European market. The first batchof City Rovers rolled out from the Tata Motorsstable in Pune on September 16, 2003.

2004: Tata Motors acquires the heavy vehiclesunit of Daewoo Motors, South Korea. TCS goespublic in July 2004 in the largest private sectorinitial public offering (IPO) in the Indian market,raising nearly $1.2 billion.

2005:Tata Steel acquires Singapore-based steelcompany NatSteel by subscribing to 100 per centequity of its subsidiary, NatSteel Asia.

2009: Tata Motors launched Tata Nano, worldscheapest family car.

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ORGANIZATION STRUCTURE(Lucknow Plant)

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TATA MOTORS-LUCKNOW PLANT

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There are three divisions in TATA Motors,Lucknow:

Training division

The Training Center at the Lucknow plant aims atproviding high quality Apprenticeship Training. Inaddition, the Centre provides both internal and externaltraining, support to operators, supervisors andmanagers in areas like special skills and technology,safety, personnel practices etc.

The Lucknow plant, after a major restructuringexercise, executed a smooth transition from function-based to process-based structure. By this structure,process owners are required to meet stretched targets,and in order to do so, are required to encourageindividual learning and development of employees. Astructured process is being followed to establish andreinforce an environment that encourages innovation.

Assembly division

Lucknow Plant started with the assembly of MediumCommercial Vehicles (MCVs) to meet the demand in theNorthern Indian market. However, in 1995, the unitstarted manufacturing bus chassis of Light CommercialVehicles (LCVs) and SUMOs. The facilities formanufacturing the spare parts were set up and startedsupply of Crown wheel & pinion (CWP) in 1994.Subsequently, G-16 & G-18 Gear Parts started in 1998.With the availability of G-16 gear parts manufacturingfacility, the Plant also started assembly of G-16 GearBox to meet in-house requirement for SUMO vehicles in

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the year 2000.Now TATA Motors Lucknow has startedassembling of CNG MCV`s to meet the consumersdemand. TATA Motors is also producing Rear EngineCV`s.

Manufacturing Division

In TATA Motors Lucknow Crown Wheel and Pinion aremanufactured by various gear cutting process.Machining (grinding and heat treatment) of Gear Box

parts is also done here. These gears are used in gearboxes or as spares. Now TATA Motors is assemblingGear Box of ACE (Newly launched small CV) inLucknow itself. The Manufacturing unit of Tata Motorsat Lucknow is the latest manufacturing facility of Tatamotors and is located towards East of Lucknow plant.

WHAT IS A CROWN WHEEL

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A crown wheel is a type of circular gear wheel withteeth that extend perpendicular to the base. While atraditional gear features teeth that sit parallel to theedges of the base, a crown wheel's teeth sit on thesurface of the wheel, forming a crown-like shape.Crown wheels are considered a type of beveled gear,which is the general term for all gears with teethlocated on the surface of the wheel rather than theedges. The teeth on a beveled wheel may be placed atany angle to the surface, while the crown wheel teethare distinguished by the fact that they are positioned ata 90-degree angle to the gear.

These gears are often used along with a pinion torotate a mechanical device. They are used in manyautomotive applications, as well as in industrial andmanufacturing equipment. Many vehicles rely on crownwheel and pinion systems to create the vehicle's

forward motion, or to rotate the axles. A crown wheelgear is also used with a pinion to operate a traditionalmechanical clock.

While standard gears line up edge to edge, crownwheels mesh at an angle with pinions or other gears.Rather than being located in the same plane, the twogears are positioned at an angle, or perpendicular toone another. This allows the teeth in the gears to fit

together and transfer motion or force between variousoperating components.

There are three basic types of crown wheel for buyersto choose from. Standard models have squared-offteeth that sit parallel to the top of the gear. This designresults in a high level of vibration and noise when thesegears are used. Spiral gears use teeth with angled

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edges, resulting in quieter performance, but also infaster wear and more maintenance. Hypoid crownwheels are similar to spiral models, but work with anoffset pinion to create better strength andperformance.

Users should select crown wheel gears carefully tomatch the needs of the application. The size andpattern of the teeth on the wheel must fit exactly withall adjacent gears or pinions. It is also helpful to choose

higher quality gears, because are more precisely madeto minimize noise and vibration. The material used tomanufacture these gears is also a critical factor. If onegear is harder than the adjacent one, it will rapidlywear away the edges of the softer gear, shortening thelife of the installation.

Figure 1USE OF CROWN AND PINION IN ANDIFFERENTIAL OF AN AUTOMOBILE

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GEARS

A gear is a rotatingmachine part having cut teeth, orcogs, which mesh with another toothed part in order totransmit torque. Two or more gears working in tandemare called a transmission and can produce amechanical advantage through a gear ratio and thus

may be considered a simple machine. Geared devicescan change the speed, magnitude, and direction of apower source. The most common situation is for a gearto mesh with another gear, however a gear can alsomesh a non-rotating toothed part, called a rack,thereby producing translation instead of rotation.

The gears in a transmission are analogous to thewheels in a pulley. An advantage of gears is that the

teeth of a gear prevent slipping.When two gears of unequal number of teeth arecombined a mechanical advantage is produced, withboth the rotational speeds and the torques of the twogears differing in a simple relationship.

In transmissions which offer multiple gear ratios, suchas bicycles and cars, the term gear, as in first gear,

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refers to a gear ratio rather than an actual physicalgear. The term is used to describe similar devices evenwhen gear ratio is continuous rather than discrete, orwhen the device does not actually contain any gears,as in a continuously variable transmission.

Comparison with other drivemechanisms

The definite velocity ratio which results from havingteeth gives gears an advantage over other drives (suchas traction drives and V-belts) in precision machinessuch as watches that depend upon an exact velocityratio. In cases where driver and follower are in closeproximity gears also have an advantage over otherdrives in the reduced number of parts required; thedownside is that gears are more expensive to

manufacture and their lubrication requirements mayimpose a higher operating cost.

The automobiletransmission allows selection betweengears to give various mechanical advantages.

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TYPES

1.External vs. internal gears

Internal gear

An external gearis one with the teeth formed on theouter surface of a cylinder or cone. Conversely, aninternal gearis one with the teeth formed on the innersurface of a cylinder or cone. For bevel gears, aninternal gear is one with the pitch angle exceeding 90degrees. Internal gears do not cause direction reversal.

2.Spur

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Spur gear

Spur gears or straight-cut gears are the simplest typeof gear. They consist of a cylinder or disk, and with theteeth projecting radially, and although they are notstraight-sided in form, the edge of each tooth thus isstraight and aligned parallel to the axis of rotation.

These gears can be meshed together correctly only ifthey are fitted to parallel axles.

3. Helical

Helical gears

Top: parallel configuration

Bottom: crossed configuration

Helical gears offer a refinement over spur gears. Theleading edges of the teeth are not parallel to the axis ofrotation, but are set at an angle. Since the gear is

curved, this angling causes the tooth shape to be asegment of a helix. Helical gears can be meshed in a

parallel or crossedorientations. The former refers towhen the shafts are parallel to each other; this is themost common orientation. In the latter, the shafts arenon-parallel.

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The angled teeth engage more gradually than do spurgear teeth causing them to run more smoothly andquietly. With parallel helical gears, each pair of teethfirst make contact at a single point at one side of thegear wheel; a moving curve of contact then growsgradually across the tooth face to a maximum thenrecedes until the teeth break contact at a single pointon the opposite side. In spur gears teeth suddenly meetat a line contact across their entire width causing stressand noise. Spur gears make a characteristic whine athigh speeds and can not take as much torque as helicalgears. Whereas spur gears are used for low speedapplications and those situations where noise control isnot a problem, the use of helical gears is indicatedwhen the application involves high speeds, large powertransmission, or where noise abatement is important.

The speed is considered to be high when the pitch linevelocity exceeds 25 m/s.

A disadvantage of helical gears is a resultant thrustalong the axis of the gear, which needs to beaccommodated by appropriate thrust bearings, and agreater degree ofsliding friction between the meshingteeth, often addressed with additives in the lubricant.

For a crossed configuration the gears must have thesame pressure angle and normal pitch, however the

helix angle and handedness can be different. Therelationship between the two shafts is actually definedby the helix angle(s) of the two shafts and thehandedness, as defined:

E = 1 + 2 for gears of the same handedness

E = 1 2 for gears of opposite handedness

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Where is the helix angle for the gear. The crossedconfiguration is less mechanically sound because thereis only a point contact between the gears, whereas inthe parallel configuration there is a line contact.

Quite commonly helical gears are used with the helixangle of one having the negative of the helix angle ofthe other; such a pair might also be referred to ashaving a right-handed helix and a left-handed helix ofequal angles. The two equal but opposite angles add to

zero: the angle between shafts is zero that is, theshafts areparallel. Where the sum or the difference (asdescribed in the equations above) is not zero the shaftsare crossed. For shafts crossedat right angles the helixangles are of the same hand because they must add to90 degrees.

4. Double helical

Double helical gears

Double helical gears, or herringbone gear, overcomethe problem of axial thrust presented by "single" helicalgears by having two sets of teeth that are set in a Vshape. Each gear in a double helical gear can bethought of as two standard mirror image helical gears

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stacked. This cancels out the thrust since each half ofthe gear thrusts in the opposite direction. Doublehelical gears are more difficult to manufacture due totheir more complicated shape.

For each possible direction of rotation, there are twopossible arrangements of two oppositely-orientedhelical gears or gear faces. In one possible orientation,the helical gear faces are oriented so that the axialforce generated by each is in the axial direction away

from the center of the gear; this arrangement isunstable. In the second possible orientation, which isstable, the helical gear faces are oriented so that eachaxial force is toward the mid-line of the gear. In botharrangements, when the gears are aligned correctly,the total (or net) axial force on each gear is zero. If thegears become misaligned in the axial direction, theunstable arrangement generates a net force for

disassembly of the gear train, while the stablearrangement generates a net corrective force. If thedirection of rotation is reversed, the direction of theaxial thrusts is reversed, a stable configurationbecomes unstable, and vice versa.

Stable double helical gears can be directlyinterchanged with spur gears without any need fordifferent bearings.

5. Bevel

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Bevel gear

A bevel gear is shaped like a right circular cone withmost of its tip cut off. When two bevel gears mesh theirimaginary vertices must occupy the same point. Theirshaft axes also intersect at this point, forming anarbitrary non-straight angle between the shafts. Theangle between the shafts can be anything except zeroor 180 degrees. Bevel gears with equal numbers ofteeth and shaft axes at 90 degrees are called miter

gears.The teeth of a bevel gear may be straight-cut as withspur gears, or they may be cut in a variety of othershapes. Spiral bevel gearteeth are curved along thetooth's length and set at an angle, analogously to theway helical gear teeth are set at an angle compared tospur gear teeth.Zerol bevel gears have teeth which arecurved along their length, but not angled. Spiral bevelgears have the same advantages and disadvantagesrelative to their straight-cut cousins as helical gears doto spur gears. Straight bevel gears are generally usedonly at speeds below 5 m/s (1000 ft/min), or, for smallgears, 1000 r.p.m.

6. Hypoid

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Hypoid gear

Hypoid gears resemble spiral bevel gears except theshaft axes do not intersect. The pitch surfaces appearconical but, to compensate for the offset shaft, are infact hyperboloids of revolution. Hypoid gears arealmost always designed to operate with shafts at 90degrees. Depending on which side the shaft is offset to,relative to the angling of the teeth, contact betweenhypoid gear teeth may be even smoother and more

gradual than with spiral bevel gear teeth. Also, thepinion can be designed with fewer teeth than a spiralbevel pinion, with the result that gear ratios of 60:1 andhigher are feasible using a single set of hypoid gears.

This style of gear is most commonly found inmechanical differentials.

7. Crown

Crown gear

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Crown gears or contrate gears are a particular form ofbevel gear whose teeth project at right angles to theplane of the wheel; in their orientation the teethresemble the points on a crown. A crown gear can onlymesh accurately with another bevel gear, althoughcrown gears are sometimes seen meshing with spurgears. A crown gear is also sometimes meshed with anescapement such as found in mechanical clocks.

8. Worm

Worm gear

Worm gears resemble screws. A worm gear is usuallymeshed with an ordinary looking, disk-shaped gear,which is called the gear, wheel, or worm wheel.

Worm-and-gear sets are a simple and compact way to

achieve a high torque, low speed gear ratio. Forexample, helical gears are normally limited to gearratios of less than 10:1 while worm-and-gear sets varyfrom 10:1 to 500:1. A disadvantage is the potential forconsiderable sliding action, leading to low efficiency.

Worm gears can be considered a species of helicalgear, but its helix angle is usually somewhat large(close to 90 degrees) and its body is usually fairly long

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in the axial direction; and it is these attributes whichgive it its screw like qualities. The distinction between aworm and a helical gear is made when at least onetooth persists for a full rotation around the helix. If thisoccurs, it is a 'worm'; if not, it is a 'helical gear'. A wormmay have as few as one tooth. If that tooth persists forseveral turns around the helix, the worm will appear,superficially, to have more than one tooth, but whatone in fact sees is the same tooth reappearing atintervals along the length of the worm. The usual screwnomenclature applies: a one-toothed worm is calledsingle threador single start; a worm with more thanone tooth is called multiple threador multiple start. Thehelix angle of a worm is not usually specified. Instead,the lead angle, which is equal to 90 degrees minus thehelix angle, is given.

In a worm-and-gear set, the worm can always drive the

gear. However, if the gear attempts to drive the worm,it may or may not succeed. Particularly if the lead angleis small, the gear's teeth may simply lock against theworm's teeth, because the force componentcircumferential to the worm is not sufficient toovercome friction. Worm-and-gear sets that do lock arecalled self locking, which can be used to advantage,as for instance when it is desired to set the position of a

mechanism by turning the worm and then have themechanism hold that position. An example is themachine head found on some types ofstringedinstruments.

If the gear in a worm-and-gear set is an ordinary helicalgear only a single point of contact will be achieved. Ifmedium to high power transmission is desired, the

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tooth shape of the gear is modified to achieve moreintimate contact by making both gears partiallyenvelop each other. This is done by making bothconcave and joining them at a saddle point; this iscalled a cone-drive.

Worm gears can be right or left-handed following thelong established practice for screw threads.

9. Non-circular

Non-circular gears

Non-circular gears are designed for special purposes.While a regular gear is optimized to transmit torque toanother engaged member with minimum noise andwear and maximum efficiency, a non-circular gear'smain objective might be ratio variations, axledisplacement oscillations and more. Commonapplications include textile machines, potentiometers

and continuously variable transmissions.

10. Rack and pinion

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Rack and pinion gearing

A rack is a toothed bar or rod that can be thought of asa sector gear with an infinitely large radius ofcurvature. Torque can be converted to linear force bymeshing a rack with a pinion: the pinion turns; the rackmoves in a straight line. Such a mechanism is used inautomobiles to convert the rotation of the steeringwheel into the left-to-right motion of the tie rod(s).Racks also feature in the theory of gear geometry,where, for instance, the tooth shape of aninterchangeable set of gears may be specified for therack (infinite radius), and the tooth shapes for gears ofparticular actual radii then derived from that. The rackand pinion gear type is employed in a rack railway.

11. Epicyclic

Epicyclic gearing

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In epicyclic gearing one or more of the gear axesmoves. Examples are sun and planet gearing (seebelow) and mechanical differentials.

12. Sun and planet

Sun (yellow) and planet (red) gearing

Sun and planet gearing was a method of convertingreciprocal motion into rotary motion in steam engines.It played an important role in the Industrial Revolution.

The Sun is yellow, the planet red, the reciprocatingcrank is blue, the flywheel is green and the driveshaft isgrey.

14. Harmonic drive

Harmonic drive gearing

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A harmonic drive is a specialized proprietary gearingmechanism.

15. Cage gear

A cage gear, also called a lantern gearor lantern pinionhas cylindrical rods for teeth, parallel to the axle andarranged in a circle around it, much as the bars on around bird cage or lantern. The assembly is heldtogether by disks at either end into which the toothrods and axle are set.

NomenclatureGeneral nomenclature

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Rotational frequency, n

Measured in rotation over time, such as RPM.

Angular frequency,

Measured in radians per second. 1RPM = / 30

rad/second

Number of teeth, N

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How many teeth a gear has, an integer. In the case

of worms, it is the number of thread starts that theworm has.

Gear, wheel

The larger of two interacting gears.

Pinion

The smaller of two interacting gears.

Path of contact

Path followed by the point of contact between two

meshing gear teeth.

Line of action, pressure line

Line along which the force between two meshing

gear teeth is directed. It has the same direction as

the force vector. In general, the line of action

changes from moment to moment during the

period of engagement of a pair of teeth. For

involute gears, however, the tooth-to-tooth force is

always directed along the same linethat is, the

line of action is constant. This implies that for

involute gears the path of contact is also a straight

line, coincident with the line of actionas is indeed

the case.

Axis

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Axis of revolution of the gear; center line of the

shaft.Pitch point, p

Point where the line of action crosses a line joining

the two gear axes.

Pitch circle, pitch line

Circle centered on and perpendicular to the axis,

and passing through the pitch point. A predefined

diametral position on the gear where the circular

tooth thickness, pressure angle and helix angles

are defined.

Pitch diameter, d

A predefined diametral position on the gear where

the circular tooth thickness, pressure angle and

helix angles are defined. The standard pitch

diameter is a basic dimension and cannot be

measured, but is a location where other

measurements are made. Its value is based on the

number of teeth, the normal module (or normal

diametral pitch), and the helix angle. It is

calculated as:

in metric units or in imperial units.

Module, m

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A scaling factor used in metric gears with units in

millimeters who's effect is to enlarge the geartooth size as the module increases and reduce the

size as the module decreases. Module can be

defined in the normal (mn), the transverse (mt), or

the axial planes (ma) depending on the design

approach employed and the type of gear being

designed. Module is typically an input value into

the gear design and is seldom calculated.Operating pitch diameters

Diameters determined from the number of teeth

and the center distance at which gears operate.

Example for pinion:

Pitch surface

In cylindrical gears, cylinder formed by projecting a

pitch circle in the axial direction. More generally,

the surface formed by the sum of all the pitch

circles as one moves along the axis. For bevel

gears it is a cone.

Angle of action

Angle with vertex at the gear center, one leg on

the point where mating teeth first make contact,

the other leg on the point where they disengage.

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Arc of action

Segment of a pitch circle subtended by the angleof action.

Pressure angle,

The complement of the angle between the

direction that the teeth exert force on each other,

and the line joining the centers of the two gears.

For involute gears, the teeth always exert forcealong the line of action, which, for involute gears,

is a straight line; and thus, for involute gears, the

pressure angle is constant.

Outside diameter, Do

Diameter of the gear, measured from the tops of

the teeth.

Root diameter

Diameter of the gear, measured at the base of the

tooth.

Addendum, a

Radial distance from the pitch surface to theoutermost point of the tooth. a = (Do D) / 2

Dedendum, b

Radial distance from the depth of the tooth trough

to the pitch surface. b = (D rootdiameter) / 2

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Whole depth, ht

The distance from the top of the tooth to the root;it is equal to addendum plus dedendum or to

working depth plus clearance.

Clearance

Distance between the root circle of a gear and the

addendum circle of its mate.

Working depth

Depth of engagement of two gears, that is, the

sum of their operating addendums.

Circular pitch, p

Distance from one face of a tooth to the

corresponding face of an adjacent tooth on thesame gear, measured along the pitch circle.

Diametral pitch,pd

Ratio of the number of teeth to the pitch diameter.

Could be measured in teeth per inch or teeth per

centimeter.

Base circle

In involute gears, where the tooth profile is the

involute of the base circle. The radius of the base

circle is somewhat smaller than that of the pitch

circle.

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Base pitch, normal pitch,pb

In involute gears, distance from one face of a toothto the corresponding face of an adjacent tooth on

the same gear, measured along the base circle.

Interference

Contact between teeth other than at the intended

parts of their surfaces.

Interchangeable set

A set of gears, any of which will mate properly with

any other.

Helical gear nomenclature

Helix angle,

Angle between a tangent to the helix and the gearaxis. Is zero in the limiting case of a spur gear.

Normal circular pitch,pn

Circular pitch in the plane normal to the teeth.

Transverse circular pitch, p

Circular pitch in the plane of rotation of the gear.Sometimes just called "circular pitch".pn =pcos()

Several other helix parameters can be viewed either inthe normal or transverse planes. The subscript nusually indicates the normal.

Worm gear nomenclature

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Lead

Distance from any point on a thread to thecorresponding point on the next turn of the same

thread, measured parallel to the axis.

Linear pitch, p

Distance from any point on a thread to the

corresponding point on the adjacent thread,

measured parallel to the axis. For a single-threadworm, lead and linear pitch are the same.

Lead angle,

Angle between a tangent to the helix and a plane

perpendicular to the axis. Note that it is the

complement of the helix angle which is usually

given for helical gears.

Pitch diameter, dw

Same as described earlier in this list. Note that for

a worm it is still measured in a plane perpendicular

to the gear axis, not a tilted plane.

Subscript w denotes the worm, subscript g denotes thegear.

Tooth contact nomenclature

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Line of contactPath ofaction Line of

action

Plane ofaction

Lines of contact(helical gear)

Arc ofaction

Length ofaction

Limitdiameter

Face advance Zone ofaction

Point of contact

Any point at which two tooth profiles touch each

other.

Line of contact

A line or curve along which two tooth surfaces are

tangent to each other.

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Path of action

The locus of successive contact points between apair of gear teeth, during the phase of

engagement. For conjugate gear teeth, the path of

action passes through the pitch point. It is the

trace of the surface of action in the plane of

rotation.

Line of actionThe path of action for involute gears. It is the

straight line passing through the pitch point and

tangent to both base circles.

Surface of action

The imaginary surface in which contact occurs

between two engaging tooth surfaces. It is thesummation of the paths of action in all sections of

the engaging teeth.

Plane of action

The surface of action for involute, parallel axis

gears with either spur or helical teeth. It is tangent

to the base cylinders.

Zone of action (contact zone)

For involute, parallel-axis gears with either spur or

helical teeth, is the rectangular area in the plane of

action bounded by the length of action and the

effective face width.

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Path of contact

The curve on either tooth surface along whichtheoretical single point contact occurs during the

engagement of gears with crowned tooth surfaces

or gears that normally engage with only single

point contact.

Length of action

The distance on the line of action through whichthe point of contact moves during the action of the

tooth profile.

Arc of action, Qt

The arc of the pitch circle through which a tooth

profile moves from the beginning to the end of

contact with a mating profile.

Arc of approach, Qa


profile moves from its beginning of contact until

the point of contact arrives at the pitch point.

Arc of recess, Qr


profile moves from contact at the pitch point until

contact ends.

Contact ratio, mc,

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The number of angular pitches through which a

tooth surface rotates from the beginning to theend of contact.In a simple way, it can be defined as

a measure of the average number of teeth in

contact during the period in which a tooth comes

and goes out of contact with the mating gear.

Transverse contact ratio, mp,

The contact ratio in a transverse plane. It is theratio of the angle of action to the angular pitch. For

involute gears it is most directly obtained as the

ratio of the length of action to the base pitch.

Face contact ratio, mF,

The contact ratio in an axial plane, or the ratio of

the face width to the axial pitch. For bevel and

hypoid gears it is the ratio of face advance to

circular pitch.

Total contact ratio, mt,

The sum of the transverse contact ratio and the

face contact ratio.

= +

mt = mp + mF

Modified contact ratio, mo

For bevel gears, the square root of the sum of the

squares of the transverse and face contact ratios.

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Limit diameter

Diameter on a gear at which the line of action

intersects the maximum (or minimum for internal

pinion) addendum circle of the mating gear. This is

also referred to as the start of active profile, the

start of contact, the end of contact, or the end of

active profile.

Start of active profile (SAP)

Intersection of the limit diameter and the involute

profile.

Face advance

Distance on a pitch circle through which a helicalor spiral tooth moves from the position at which

contact begins at one end of the tooth trace on the

pitch surface to the position where contact ceases

at the other end.

Tooth thickness nomeclature

Tooththickness

Thicknessrelationships

Chordalthickness Tooth thickness

measurement

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over pins

Spanmeasuremen

t

Long andshort

addendumteeth

Circular thickness

Length of arc between the two sides of a gear

tooth, on the specified datum circle.

Transverse circular thickness

Circular thickness in the transverse plane.

Normal circular thickness

Circular thickness in the normal plane. In a helical

gear it may be considered as the length of arc

along a normal helix.

Axial thickness

In helical gears and worms, tooth thickness in an

axial cross section at the standard pitch diameter.

Base circular thickness

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In involute teeth, length of arc on the base circle

between the two involute curves forming theprofile of a tooth.

Normal chordal thickness

Length of the chord that subtends a circular

thickness arc in the plane normal to the pitch helix.

Any convenient measuring diameter may be

selected, not necessarily the standard pitchdiameter.

Chordal addendum (chordal height)

Height from the top of the tooth to the chord

subtending the circular thickness arc. Any

convenient measuring diameter may be selected,

not necessarily the standard pitch diameter.

Profile shift

Displacement of the basic rack datum line from the

reference cylinder, made non-dimensional by

dividing by the normal module. It is used to specify

the tooth thickness, often for zero backlash.

Rack shift

Displacement of the tool datum line from the

reference cylinder, made non-dimensional by

dividing by the normal module. It is used to specify

the tooth thickness.

Measurement over pins

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Measurement of the distance taken over a pin

positioned in a tooth space and a referencesurface. The reference surface may be the

reference axis of the gear, a datum surface or

either one or two pins positioned in the tooth space

or spaces opposite the first. This measurement is

used to determine tooth thickness.

Span measurement

Measurement of the distance across several teeth

in a normal plane. As long as the measuring device

has parallel measuring surfaces that contact on an

unmodified portion of the involute, the

measurement will be along a line tangent to the

base cylinder. It is used to determine tooth

thickness.Modified addendum teeth

Teeth of engaging gears, one or both of which

have non-standard addendum.

Full-depth teeth

Teeth in which the working depth equals 2.000

divided by the normal diametral pitch.

Stub teeth

Teeth in which the working depth is less than

2.000 divided by the normal diametral pitch.

Equal addendum teeth

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Teeth in which two engaging gears have equal

addendums.Long and short-addendum teeth

Teeth in which the addendums of two engaging

gears are unequal.

Pitch nomenclature

Pitch is the distance between a point on one tooth and

the corresponding point on an adjacent tooth. It is adimension measured along a line or curve in thetransverse, normal, or axial directions. The use of thesingle wordpitch without qualification may beambiguous, and for this reason it is preferable to usespecific designations such as transverse circular pitch,normal base pitch, axial pitch.

Pitch Tooth pitchBase pitchrelationships

Principalpitches

Circular pitch,p

Arc distance along a specified pitch circle or pitchline between corresponding profiles of adjacent

teeth.

Transverse circular pitch,pt

Circular pitch in the transverse plane.

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Normal circular pitch,pn,pe

Circular pitch in the normal plane, and also thelength of the arc along the normal pitch helix

between helical teeth or threads.

Axial pitch,px

Linear pitch in an axial plane and in a pitch

surface. In helical gears and worms, axial pitch has

the same value at all diameters. In gearing of othertypes, axial pitch may be confined to the pitch

surface and may be a circular measurement. The

term axial pitch is preferred to the term linear

pitch. The axial pitch of a helical worm and the

circular pitch of its worm gear are the same.

Normal base pitch,pN,pbn

An involute helical gear is the base pitch in the

normal plane. It is the normal distance between

parallel helical involute surfaces on the plane of

action in the normal plane, or is the length of arc

on the normal base helix. It is a constant distance

in any helical involute gear.

Transverse base pitch,pb,pbt

In an involute gear, the pitch on the base circle or

along the line of action. Corresponding sides of

involute gear teeth are parallel curves, and the

base pitch is the constant and fundamental

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distance between them along a common normal in

a transverse plane.Diametral pitch (transverse), Pd

Ratio of the number of teeth to the standard pitch

diameter in inches.

Normal diametral pitch, Pnd

Value of diametral pitch in a normal plane of a

helical gear or worm.

Angular pitch, N,

Angle subtended by the circular pitch, usually

expressed in radians.

degrees or radians

Backlash

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Backlash is the error in motion that occurs when gearschange direction. It exists because there is alwayssome gap between the trailing face of the driving toothand the leading face of the tooth behind it on thedriven gear, and that gap must be closed before forcecan be transferred in the new direction. The term"backlash" can also be used to refer to the size of thegap, not just the phenomenon it causes; thus, onecould speak of a pair of gears as having, for example,"0.1 mm of backlash." A pair of gears could bedesigned to have zero backlash, but this wouldpresuppose perfection in manufacturing, uniformthermal expansion characteristics throughout thesystem, and no lubricant. Therefore, gear pairs aredesigned to have some backlash. It is usually providedby reducing the tooth thickness of each gear by halfthe desired gap distance. In the case of a large gearand a small pinion, however, the backlash is usuallytaken entirely off the gear and the pinion is given fullsized teeth. Backlash can also be provided by movingthe gears farther apart.

For situations, such as instrumentation and control,where precision is important, backlash can beminimised through one of several techniques. Forinstance, the gear can be split along a plane

perpendicular to the axis, one half fixed to the shaft inthe usual manner, the other half placed alongside it,free to rotate about the shaft, but with springs betweenthe two halves providing relative torque between them,so that one achieves, in effect, a single gear withexpanding teeth. Another method involves tapering theteeth in the axial direction and providing for the gear tobe slid in the axial direction to take up slack.

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Shifting of gearsIn some machines (e.g., automobiles) it is necessary toalter the gear ratio to suit the task. There are severalmethods of accomplishing this. For example:

Manual transmission

Automatic gearbox

Derailleur gears which are actually sprockets in

combination with a roller chain Hub gears (also called epicyclic gearing or sun-

and-planet gears)

There are several outcomes of gear shifting in motorvehicles. In the case ofair pollution emissions, thereare higher pollutant emissions generated in the lowergears, when the engine is working harder than whenhigher gears have been attained. In the case ofvehiclenoise emissions, there are higher sound levels emittedwhen the vehicle is engaged in lower gears. This facthas been utilized in analyzing vehicle generated soundsince the late 1960s, and has been incorporated intothe simulation of urban roadway noise andcorresponding design of urban noise barriers alongroadways.

Tooth profile

Profile of a spurgear

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Undercut

A profile is one side of a tooth in a cross sectionbetween the outside circle and the root circle. Usually aprofile is the curve of intersection of a tooth surfaceand a plane or surface normal to the pitch surface, suchas the transverse, normal, or axial plane.

The fillet curve (root fillet) is the concave portion of thetooth profile where it joins the bottom of the toothspace.

As mentioned near the beginning of the article, theattainment of a non fluctuating velocity ratio isdependent on the profile of the teeth. Friction and wearbetween two gears is also dependent on the toothprofile. There are a great many tooth profiles that willgive a constant velocity ratio, and in many cases, givenan arbitrary tooth shape, it is possible to develop a

tooth profile for the mating gear that will give aconstant velocity ratio. However, two constant velocitytooth profiles have been by far the most commonlyused in modern times. They are the cycloid and theinvolute. The cycloid was more common until the late1800s; since then the involute has largely supersededit, particularly in drive train applications. The cycloid isin some ways the more interesting and flexible shape;

however the involute has two advantages: it is easier tomanufacture, and it permits the center to centerspacing of the gears to vary over some range withoutruining the constancy of the velocity ratio. Cycloidalgears only work properly if the center spacing is exactlyright. Cycloidal gears are still used in mechanicalclocks.

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An undercut is a condition in generated gear teethwhen any part of the fillet curve lies inside of a linedrawn tangent to the working profile at its point of

juncture with the fillet. Undercut may be deliberatelyintroduced to facilitate finishing operations. Withundercut the fillet curve intersects the working profile.Without undercut the fillet curve and the workingprofile have a common tangent.

Gear materials

Wooden gears of a historic windmill

Numerous nonferrous alloys, cast irons, powder-metallurgy and even plastics are used in themanufacture of gears. However steels are mostcommonly used because of their high strength toweight ratio and low cost. Plastic is commonly used

where cost or weight is a concern. A properly designedplastic gear can replace steel in many cases because ithas many desirable properties, including dirt tolerance,low speed meshing, and the ability to "skip" quite well.Manufacturers have employed plastic gears to makeconsumer items affordable in items like copy machines,

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optical storage devices, VCRs, cheap dynamos,consumer audio equipment, servo motors, and printers.

The module system

Countries which have adopted the metric systemgenerally use the module system. As a result, the termmodule is usually understood to mean the pitchdiameter in millimeters divided by the number of teeth.When the module is based upon inch measurements, itis known as the English module to avoid confusion with

the metric module. Module is a direct dimension,whereas diametral pitch is an inverse dimension (like"threads per inch"). Thus, if the pitch diameter of agear is 40 mm and the number of teeth 20, the moduleis 2, which means that there are 2 mm of pitchdiameter for each tooth.

Manufacture

.

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Gear are most commonly produced via hobbing, butthey are also shaped, broached, cast, and in the case ofplastic gears, injection molded. For metal gears theteeth are usually heat treated to make them hard andmore wear resistant while leaving the core soft andtough. For large gears that are prone to warp a quenchpress is used.

GLEASON NO.610 HYPOID CUTTER

MACHINE DESCRIPTION

GENERAL DESCRIPTION-TheNo.610 Universal

Hypoid Gear Machine sets new standards in precisionhigh speed roughing and finishing of medium and

large non-generated hypoid and spiral bevel

gears.The No.610 Machine offers many production

and advantages where quantities are insufficient to

justify separate roughing and finishing

machines.Desinged primarily for use in the

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truck,tractor and off the road equipment field,the

No.610 accomodate gear members upto 20 indiameter and a minimum ratio of 2-1/4-1.maximum

whole depth is 1.000.

When the work head is in the horizontal

level- load position,the work can be rapidly and

conveniently loaded.This feature provides the added

benefit of safety.The work spindle is widely separated

from the cutter,when the gears are mounted orremoved.

An overhead tieprovides a fixed relationship

between cutter and work.When the work head is

raised into the cutting position,the tie is hydraulically

clamped.Hydraulic pressure on the clamp is

maintained through the cutting cycle.A new hydraulic mechanism rigidly clamps

the work spindle to the housing,providing increased

rigidity during cutting and loading to improved surface

finish and tooth spacing.The clamp is automatically

released each time the work is indexed.In additionto

the overhead tie and the work spindle clamp,rigidity is

assured as the cutting forces are directed verticallydownwards against the machine bed.When the work

head is raised into cutting position,the rotating cutter

contacts the work,so that the blades pass down the

tooth slotlocated at the lowest point on the roughed

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gear.This design utilizes the weight of the machine in

obtaining maximum rigidity.

Figure 2GLEASON 610 HYPOID CUTTER MACHINE

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CUTTING METHODS-

1.FORMATE-No generating motion isemployed.Roughed out gears are finished accurately

and quickly by the single cycle cutter,which rotates

uniformly completing one tooth with each

revolution.Indexing takes place in the large gap of the

cutterand the machine stops automatically at the

completion of the last tooth.

Roughing is accomplished by a simple depth

feed motion of the cutter into the work .indexing takes

place when the cutter withdraws from the tooth

slot.One tooth slot is roughed with ech revolution of

the feed cam.The number of turns of the cutter

depends on the depth of the tooth slot.

2.CYCLEX-For low production quantities,the CYCLEXmethod may be used to rapidly produce

FORMATE,hypoid and spiral bevel gears in one

operation from the solid.

In this form of CYCLEX cutter,the roughing

and semi-finishing blades are of gradually increasing

height and the two finishing blades are located so thattheir top and cutting edges are slightly below those of

the other blades.

During the cutting cycle.the cutter makes a

number of revolution for roughing operation,as the

cutter is fed into the work by means of cam.Since the

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finishing blades are set lower than the preceding

blades they do not engage the work during thisposition of the cutting cycle.

As the semi-finishing blades are passing

through the tooth slot at full roughing depth,the cutter

speed is reduced.The cutter is then quickly

advanced,and the two finishing blades complete the

tooth profile shape. The cutter is then rapidly

withdrawn so that the roughing blades do not contactthe work. Further withdrawal of the cutter provides

clearance necessary for indexing.

3.HELIX FORM-As each blade of a HELIX FORM cutter

passes through a tooth space,the cutter is advanced

axially then quickly withdrawn, before the following

cutter blade enters the tooth space. The combinedmotion makes the path of the cutter tip tangent to the

root plane of the gear being cut.

The cutter computes one tooth with each

revolution. Indexing takes place when the large gap in

the cutter is beside the blank.

The HELIX FORM method of cutting producesgear tooth surfaces which are close to the true

mathematical conjugacy with the mating pinion. It

also minimises development.

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Figure 3CUTTING ON GLEASON NO.610

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Figure 4GLEASON 610

Figure 5CROWN MANUFACTURED ON GLEASON NO.610

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Figure 6CROWN WHEEL

CUTTING CYCLE AUTOMATIC MODE ROUGHING

AND CYCLEX-A blank is mounted on the work spindle

and chucked manually. The cycle starts and the dual

control buttons are activated, the work head raises to

the cutting position, is hydraulically clamped for rigidity

and the feed and coolant motor starts.

The cutting cycle is controlled by the feed

cam which feeds the cutter into the work. Indexing

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and Chamfering is done during a dwell in the feed

cam while the cutter is in the rear position. In the caseof CYCLEX cutting set-in takes place at full depth as

the two finishing blades pass through the cut. After

all the teeth have been cut, the machine

automatically stops, the work head unclamps and

lowers to the loading positon.

HELIX FORM AND SINGLE CYCLE FINISHING-A

roughed gear is mounted on the work spindle and

chucked manually. The cycle starts and dual control

buttons are activated, the work head raises to the

cutting position, is hydraulically clamped for rigidity

and the feed and coolant motors start. The cutter

completes one tooth with each revolution andindexing take place in the large gap of the cutter.

After all the tooth have been cut, the machine

automatically stops , the work head unclamps and

lowers to the loading position.

CONTROLS-

1.TEMPERATURE CONTROL LIGHT-The heaters in

the hydraulic unit warm the oil when the hydraulic

unit is running because the hydrostatic bearings for

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the cutter spindle require warm oil. The heaters are

set at the factory for 150 degrees fahrenheit and thethermostat cuts out when the temperature reaches

90. Light will come on and enable the machine to

operate.

2.GROUND LIGHTS-These lights show if a wire has

come loose somewhere and is touching the machine.

Normally these lights each have a dull pink glow . If

some wire becomes grounded, one light will dim andthe other will brighten significantly.

3.FILTER LIGHT-If filter becomes clogged , this light

will come on. The machine will be inoperative until

this filter is cleaned. The machine does not stop in the

middle of a cycle , but completes it and will not start

the next.4.AUTOMATIC PRODUCTION COUNTER-This

counter is set by the operator to the number of pieces

to be cut before the cutter is to be sharpened.

5.SHARPEN CUTTER LIGHT-This light comes on

when the machine has cut the amount of blanks

preselected on the production counter, signifying thatthe cutter should be sharpened.

6.MAIN LINE SWITCH-This switch connects and

disconnects the machine with the input power supply.

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7.CUTTER DISCONNECT SWITCH-Before changing a

cutter, rotate this handle to the lock position, thenengage and secure the latch.

8.HYDRAULIC START BUTTON-After the main line

switch is closed, depress this button to start the

hydraulic, hydrostatic bearing and lubricating pump

motors.

9.OVERSIZE BORE LIGHT-When this light is ON, itindicates the bore of the blank chucked on the arbor is

too large and the arbor drawrod has travelled too far.

This would make it unsafe to cut the part because

there would not be proper workholding pressure . The

light must be OUT to run the machine.

10.HYDRAULIC STOP MACHINE-Depress this button

to stop all machine functions. In an emergency, it ismore effective to depress this button than the cycle

button.

11.GAGE CUTTER LIGHT-When ON , this light

indicates that the cutter is at the full depth. This light

must be ON when gaging the cutter for length.

12.LOAD POSITION LIGHT- This light is ON ,whenthe feed cam stop zone is adjacent to the cam

follower. To begin an automatic cycle, this light must

be ON.

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13.RESET BUTTON-It is necessary to depress this

button prior to changing from a manual cycle to anautomatic cycle(not vice versa).

14.AUTOMATIC LIGHT-When ON , this light indicates

that an automatic machine cycle can be started by

depressing the cycle start and the dual control button.

15.WORK SPINDLE LIGHT-This light comes ON when

the work spindle revolves 360 degrees. A cam on thework spindle under the index plate contacts the 360

degrees switch. This indicates the work spindle has

made one revolution and all the teeth are cut. If the

index switch is OFF and the 360 degrees switch is

contacted , the machine can be run during setup and

not index off this position.

16.CYCLE START BUTTON-This button along withthe dual control button is used to jog the machine

from the main control panel when a manual mode is

selected and remote jog switch is set to RUN. This

button is also used to start an automatic cycle along

with the dual control button when an automatic mode

has been selected.

17.CYCLE STOP BUTTON-The machine can be

stopped at any time during an automatic cycle with

this button.

18.INDEX SWITCH-When ON , the machine can be

run in an automatic cycle.

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19.BRAKE SELECTOR SWITCH-When OFF, the feed

cam and cutter spindle can be rotated by hand. Themachine can only run with this switch in the ON

position.

20.CUTTING METHOD SELECTOR

SWITCH(CYCLEX MACHINE)-Change this switch

setting when setting up to cut a new job, different

type of cutter than previously used. Set to:

a)Finish-for Single Cycle and HELIX FORM cutters, the

main motor will run at slow speed.

b)Rough-for TRIPLEX cutters, the main motor will run

at high speed.

c)Cyclex-for CYCLEX cutters , the main motor will run

at high speed during the roughing portion of the cycle,

and will run at low speed when in finishing portion of

the cycle.

21.OUTSIDE CHAMFER SELECTOR SWITCH-This

switch is used in setting up the outside chamfering

tool and may only be used when in manual cycle

mode. When the machine is to be operated in the

automatic cycle mode, set this switch to OUT.

22.INSIDE CHAMFER SELECTOR SWITCH-This

switch is used in setting up the inside chamfering tool

and may only be used when in manual cycle mode.

When the machine is to be operated in the automatic

cycle mode, set this switch to OUT.

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23.REMOTE JOG BUTTON-This button is used to

enable the feed cam to be easily put on center mustbe set to JOG for this button to be operative, and will

make operator station inoperative when set on JOG as

a safety feature.

24.CUTTER ROTATION SWITCH-This switch allows

the use of both left hand and right hand cutters .

25.MAIN MOTOR SPEED SWITCH-Set this switch tohigh speed when roughing and to low speed when

finishing.

26.MANUAL CUTTER ROTATION-The cutter spindle

may be rotated manually by rotating the upper speed

pulley shaft when the brake is off. DO THIS ONLY

WHEN THERE IS OIL PRESSURE TO THE

HYDROSTATIC SPINDLE. The probable would beeither the cutter spindle or its housing would be

damaged.

27.DECHUCK CHUCK SELECTOR SWITCH-By

turning this switch counter clockwise , the work

holding equipment is dechucked. By turning this

switch clockwise , the work holding equipment ischucked.

28.DUAL CONTROL BUTTON-This button is used in

conjunction with the cycle start buttonto begin either

a manual or auto cycle. Both buttons must be

depressed at the same time.

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CUTTER INFORMATION

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Figure 5CUTTER USED ON GLEASON NO.610

TRIPLEX,SINGLE CYCLE,CYCLEX and HELIX FORM

cutters from 5to 18 may be used on this machine. A

marking screw , on the face of cutter head ,identifies

the blade setup by giving the point width and pointdiameter of the setup. The blades are held in place in

the slots by bolts. The last blade of each set is marked

with the following information: the point width, set

serial number, ordering number and the blades

pressure angles.

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Figure 6CUTTING PROCESS OF CROWN

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Figure 7WORKING OF GLEASON NO.610

SPECIFICATIONS

GLEASON NO.610 HYPOID GEAR MACHINE

A)CAPACITY:- ENGLISH

METRIC

1.OUTSIDE CONE DISTANCE

a)maximum 10 254mm

b)minimum 2.75 70mm

2.MAXIMUM GEAR PITCH DIAMETER 20 508mm

3.CUTTER DIAMETERS 9 TO 18

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4.WHOLE DEPTH 1.000

24.4mm

5.ROOT ANGLE 60 to 80 degrees

6.FACE WIDTH 3 76mm

7.EXTREME RATIO(MINIMUM) 2-1/4 to 1

8.NUMBER OF TEETH 20 to 75

B)WORK SPINDLE:-

1.DIAMETER OF TAPER HOLE AT LARGE END 3-27/64

2.TAPER PER FOOT 1/2"

3.DEPTH OF TAPER 5/8

C)SPEEDS AND FEEDS:-

1.CUTTER SPEED(feed per minute)FOR ROUGHING 8-200

24m-61m

2.FEEDS(seconds per tooth)FOR ROUGHING 3-35

3.CUTTER SPEED(feed per minute)FOR FINISHING 30-100 24m-61m

4.FEEDS(seconds per tooth)FOR FINISHING 3-9

D)ELECTRICAL EQUIPMENT:- 60Hz 50Hz

1.MAIN MOTOR 2 SPEED(10HP/5HP) 1800/900 RPM

1500/750 RPM

2.HYDRAULIC MOTOR 7-1/2HP1800 RPM 1500 RPM

3.COOLANT MOTOR 2HP 3600 RPM

3000 RPM

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4.CHIP CONVEYOR 1/4HP 1800 RPM 1500 RPM

5.HYDROSTATIC SPINDLE 1-1/2HP 1800 RPM 1500 RPM

E)MISCELLANEOUS:-

1.FLOOR SPACE 118*86-1/2

3000cm*2200cm

2.HEIGHT 70 1780mm

3.WEIGHT

a)net 16,500lbs 7,483kg

b) gross 17,500lbs 7,937kg

TYPES OF CROWN WHEEL AND PINIONMANUFACTURED AT TATA MOTORS AND THEIR

PER DAY OUTPUT

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TYPE OUTPUT

45/7 240

41/7 255

48/7 210

35/9 270

41/6 240

Graph showing per day output

JOB SPECIFICATION:-20Mn CR-5

CONSTITUENT

S

PERCENTAGE

Carbon 0.17-0.22

Silicon 0.15-0.35

Manganese 1.0-1.4

Chromium 1.0-1.3

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Iron Rest

IMPROVING THE PRODUCTIVITY

Metal cutting is the outwardly simple process ofremoving metal on a work piece in order to get adesired shape by using a tool, either by rotating the

workpiece (as in a lathe) or by rotating the tool (as in adrilling machine). But behind this simple process lienumerous parameters that play their roles, from asmall to a big way, in deciding many things in the act ofmetal cutting, including the speed of doing the job, thequality and accuracy of the finish, the life of the tool,the cost of production, and so on.

Some parameters involved in the metal cutting process

are in fact closely related with some other parametersin the metal cutting process; playing with one will havean influencing effect on another. Thus, even afterseveral years of experience, process planningengineers may find difficulty in confidently declaringthemselves as experts in metal cutting!

.

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1) Material machinability:

The machinability of a material decides how easy ordifficult it is to cut it. The materials hardness is onefactor that has a strong influence on the machinabilty.

Though a general statement like a soft material iseasier to cut than a harder material is true to a largeextent, it is not as simple as that. The ductility of amaterial also plays a huge role.

2) Cutting Tool Material:

In metal cutting, High Speed steel and Carbide are twomajor tool materials widely used. Ceramic tools andCBN (Cubic Boron Nitride) are the other tool materialsused for machining very tough and hard materials. Atools hardness, strength, wear resistance, and thermalstability are the characteristics that decide how fast thetool can cut efficiently on a job.

3) Cutting speed and spindle speed:

Cutting speed is the relative speed at which the toolpasses through the work material and removes metal.It is normally expressed in meters per minute (or feetper inch in British units). It has to do with the speed ofrotation of the workpiece or the tool, as the case maybe. The higher the cutting speed, the better theproductivity. For every work material and tool material

combo, there is always an ideal cutting speed available,and the tool manufacturers generally give theguidelines for it.

Spindle speed: Spindle speed is expressed in RPM(revolutions per minute). It is derived based on thecutting speed and the work diameter cut (in case ofturning/ boring) or tool diameter (in case of drilling/

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milling etc). If V is the cutting speed and D is thediameter of cutting, then Spindle speed N = V /(Pi x D)

4) Depth of cut:

It indicates how much the tool digs into the component(in mm) to remove material in the current pass.

5) Feed rate:

The relative speed at which the tool is linearlytraversed over the workpiece to remove the material.In case of rotating tools with multiple cutting teeth (likea milling cutter), the feed rate is first reckoned in termsof feed per tooth, expressed in millimeter(mm/tooth). At the next stage, it is feed perrevolution (mm/rev).

In case of lathe operations, it is feed per revolution thatstates how much a tool advances in one revolution ofworkpiece. In case of milling, feed per revolution is

nothing but feed per tooth multiplied by the number ofteeth in the cutter.

To actually calculate the time taken for cutting a job, itis feed per minute (in mm/min) that is useful. Feedper minute is nothing but feed per revolution multipliedby RPM of the spindle.

6) Tool geometry:

For the tool to effectively dig into the component toremove material most efficiently without rubbing, thecutting tool tip is normally ground to different angles(known as rake angle, clearance angles, relief angle,approach angle, etc). The role played by these anglesin a tool geometry is a vast subject in itself.

7) Coolant:

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To take away the heat produced in cutting and also toact as a lubricant in cutting to reduce tool wear,coolants are used in metal cutting. Coolants can rangefrom cutting oils, water soluble oils, oil-water spray,and so on.

8) Machine/ Spindle Power:

In the metal cutting machine, adequate power shouldbe available to provide the drives to the spindles andalso to provide feed movement to the tool to remove

the material. The power required for cutting is based onthe Metal removal rate the rate of metal removed in agiven time, generally expressed in cubic centimetersper minute, which depends on work material, toolmaterial, the cutting speed, depth of cut, and feed rate.

9) Rigidity of machine:

The rigidity of the machine is based on the design and

construction of the machine, the age and extent ofusage of the machine, the types of bearings used, thetype of construction of slide ways, and the type of driveprovided to the slides all play a role in the machining ofcomponents and getting the desired accuracies, finish,and speed of production.

Thus, in getting a component finished out of a metalcutting machine at the best possible time within the

desired levels of accuracy, tolerances, and surfacefinish, some or all the above parameters play theirroles. As already mentioned in the beginning, each ofthe parameters can create a positive or negativeimpact on other parameters, and adjustments andcompromises are to be made to arrive at the bestmetal cutting solution for a given job.

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10)Process Cycle

The time required to produce a given quantity of partsincludes the initial setup time and the cycle time foreach part. The setup time is composed of the time tosetup the milling machine, plan the tool movements(whether performed manually or by machine), andinstall the fixture device into the milling machine. Thecycle time can be divided into the following four times:

1. Load/Unload time - The time required to load theworkpiece into the milling machine and secure it tothe fixture, as well as the time to unload the finishedpart. The load time can depend on the size, weight,and complexity of the workpiece, as well as the typeof fixture.

2. Cut time - The time required for the cutter to make

all the necessary cuts in the workpiece for eachoperation. The cut time for any given operation iscalculated by dividing the total cut length for thatoperation by the feed rate, which is the speed of thecutter relative to the wo

Documents

Summer Training Report at TATA MOTORS