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ABSTRACT

This project work titled “SHEET ROLLING MACHINE” has been

conceived having studied the difficulties in making bending in sheet metal. This

project facilitates in making bending accurate in sheet metal with easy. The

project employee by using the roller for bending purpose by manual.

This machine can be used in various fields. Our project the sheet metal

rolling is very simple in operation by using roller which is coupled with handle.

In Sheet Metal working industry a wide range of power and hand operated

machines are used. This machine is simple in construction and working.

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PROJECT OBJECTIVE

To implement the skills acquired in previous semester to practical

problems as prescribed in ME-68 DESING AND FABRICATION

PROJECT, MECHANICAL ENGINEERING ANNA UNIVERSITY

curriculum to fulfil the above, we are focused in the area of

“MANUFACTURING TECHNOLOGY” subject which we have studied in

previous semester by getting basic ideas from it. We have designed and

fabricated “SHEET METAL ROLLING MACHINE” and calculated the

experimental results theoretically

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LIST OF FIGURE

PAGE NO

1.1 Stress in bending 11

3.1: Process of rolling 13

4.1 Stress induced in sheet metal 14

5.1 Steps in rolling 16

6.1 Sheet rolling machine 15

8.1Shape rolling mechanism 17

8.2 Stress and Strain Curve for Steel20

8.3 Plastic Theory of Bending 21

8.4 Geometrical analysis 22

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LIST OF CONTENT

Page No

1. Introduction 10

2. Bending 12

2.1 Roll bending 13

3. Process of rolling 13

4. Stress induced in sheet metal 15

5. Steps in rolling 16

6. Description of the machine 17

7. Working principle 18

8. Design 19

8.1 General design principles19

8.2 Stress and strain in steel 20

8.3 Plastic theory of bending 21

8.4 Design calculation 22

9. Synopsis 28

10. Application 29

11. Advantages 30

12. Disadvantage 31

13. Estimation of cost analysis 32

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1. INTRODUCTION

Sheet Metal industry is a large and growing industry. There are many special

purposes machines used in this industry to-day. The proper selection of the

machines depends upon the type of the work under-taken by the particular

industry. There are many examples of Sheet Metal work, which can be seen in

our everyday lives. The metals generally used for Sheet Metal work include

black iron sheet, copper sheet, tin plate, aluminium plate, stainless sheet and

brass sheet.

Our project the “SHET METAL ROLLING MACHINE” finds huge

application in Sheet Metal industry. Rolling is the process of bending sheets to

a curved form. The article in the shape of cylinders is made by rolling roller.

Rolling operation can be done on hand or power operated rolling machines. In

forming cylindrical shapes a gradual curve is to be put in the metal rather than

sharp bends. The gap between the rollers can be regulated by hand operated

screws

Sheet metal is available in flat pieces or as a coiled strip. Various forming process in sheet metal include

Punching Roll forming Rolling Spinning Stamping Bending Deep drawing Expanding Curling Press brake forming

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Decambering Ironing Laser cutting Incremental sheet forming etc.

1.1 BENDING

Bending is one of the most common forming operations. We merely have to

look at the components in an automobile or at a paperclip to see how many parts

shaped by bending. Bending is usually defined as the deforming of the sheet

metal along the straight line around a straight axis called neutral axis, result in

the plane surface at an angle to the original plane. During bending the top layers

are subject to tension and the bottom layer are subjected to compression. The

width of the part in the outer region is smaller and in the inner region it is larger

than the original width because of the poisson ratio as shown in fig 1.1

Fig 1.1 Stress in bending

Types of bending operation are classified into

U-Die bending V-Die bending Roll bending Bending in the four slide machine Curling Dimpling Flanging U-Die bending with spring pad

1.2 Roll bending

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A continuous form from of three-point bending is roll bending, where plates,

sheet and rolled on each end, one of the support can often be swung clear to

permit the removal of closed shapes from the rollsshapes can be bent to a

desired curvature on forming rolls. These machines usually have three roll in

the of a pyramid, with the two lower rolls being driven and the position of the

upper roll being adjustable by a frame

1.3 PROCESS OF ROLLING

In the first stage the plate is kept between top roller and bottom rollers as shown

in Figure2.1 and the top roller is given vertical displacement to get the required

bend. In next stage the bottom rollers are driven using motors in forward

direction to get the roll bending of the plate. Similarly the rollers are driven

inverse direction to get better dimensional accuracy of the final product. The

bent plate is than unloaded by raising the top roller. For continuous single-pass

four roll thin plate bending a model was proposed considering the equilibrium

of the internal and external bending moment at and about the plate-top roller

contact.

They had considered varying radius of curvature for the plate between the

rollers and proposed mathematical model to simulate the mechanics in a steady

continuous bending mode for four-roll thin plate bending process and also

investigated In sequence of material strain hardening on the mechanics of

steady continuous roll and edge-bending mode in the four-roll plate bending

process For continuous multi-pass bending of cylinder on 3-roller bending

machines (cylindrical) rollers, They incorporated the effect of change of young

modulus during the deformation in the formulation to study the effect on spring

back prediction. For plane strain of sheet metal subjected to strain rate effects

during cyclic bending under tension.

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Fig 1.2 rolling process

The roll bending process is used to be observed from the literature reviewed that

conical bending process is untouched area as far as force prediction is

concerned. Even in the industries the normal practice of plate roller bending still

heavily depends upon the experience and the skill of the operator. Working to

templates, or by trial and error.

1.4 STRESSES INDUCED IN SHEET METAL

The working by bending of work-pieces creates inner of this in

deformed zone stresses in tangential and radial directions. The metal strata

placed to curving centre are pressed in tangential directions, becoming shorter

and in especially cases are stretchingin transversal direction. The metal strata

placed to external piece are stretching in tangential direction and in especially

cases are pressed in transversal direction, making the piece narrowing. Between

the stretching and pressing strata is founded the neutral status. The neutral status

with the radius is founding displaced to the curving centre before the weight

centre,

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Fig 1.3 stress induced in sheet metal

1.5 .STEPS IN ROLLING

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Fig 1.4 Steps of rolling

2. DESCRIPTION OF THE MACHINE

The Sheet Metal Rolling Machine works according to the principle of

three point bending. The rotation of the driven rolls being utilized to feed the

metal through the rolls by means of the frictional forces present between the

surface of the rolls and sheet. No lubricant is used at its presence interference

with the ability to grip. Sheet Metal Rolling Machine essentially consists of

three rollers, used to manufacture circular components like cylinders. Sheet

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Metal Rolling Machine is classified into two types based on the arrangement of

the rollers. They are as follows.

1. Pinch type machine

2. Pyramidal type machine

This machine is of pinch type here only the top roll serves as a driven, bottom

roller are idler and rotates on friction with the work metal blank

2.1 Sheet rolling machine

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2.1 WORKING PRINCIPLE

The Sheet Metal, which is to be formed in cylindrical shape, is present at the edge by hammering. To start the operation easily and to avoid flats at the beginning and at the ends of the rolled form. In rolling cylindrical shapes a gradual curve is to be put in the metal rather than sharp bends. Now the sheet metal is introduced between the top and the bottom rolls, the gap between the top and bottom rolls are adjusted as per the required diameter by regulating the screw rods.

The rollers were arranged in triangular form; two sets of rollers below and one above. The upper roller providethe bendingforcewhilethebackbaseroller provides the required driving force and the front end

Roller bends the metal according to set radius of bend. Aperture adjuster

on each block assembly ensure loading of work piece and adjustment to

required radius of bent. The free end of the top bearing block is spring loaded

to increase or to reduce top-base roller clearance. Two other bores on each

bearing blocks provide an adjustment for the roller gap variability. Top roller

Provides the bearing load (bending force)and also compliments the driving

roller when working on thick materials. Thelowerbackroller provides the

necessary driving forces while the idler roller does the bending and material

delivery. There are two crank levers, one on the top roller and another on the

front-end roller. The lever (handle) coupling head has a square configuration

which fits into the square end of the roller shaft.

The frame structure made of (50×50×5)mm angle iron for the purposes of

strength. The tool table is provided below the rollers for safe keeping of tools

and cranks. The roller head assembly is detachable from the frame and can be

mounted on a table to be used as a table top machine for tinkering

3 .DESIGN

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3.1General design principles

Following basic shearing operation on a sheet metal, components can be

rolled to give it a definite shape.

Bending of parts depends upon material properties at the location of the

bend. To achieve bending, the work material must be subjected to two major

forces; frictional force which causes an o-slip action when metal and roller

came in contact and a bending force acting against the forward speed and the

torque applied to move the material. Fig8.1

3.2Shape rolling mechanism

Where ,a=distance from exit one to then o-slip point (assume a=L/2);

F=force applied to rollers ;T=torque applied to rollers ;L=roll gap; r=radius

of rollers ;μ=frictional force ;ho,hf=thickness of the sheet before and after

timet.

Atleast two rollers were involved in flat rolling depending on the thickness

sand properties of material while three or mutiple roller system is required in

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shape rolling. A work material under bending load is subjected to some form

of residual stress and deformation as it bends. Materials at the outer bend

radius undergo tensile plastic deformation while the material at the inner bend

radius undergoes compressive plastic deformation.

3.2.1 Stress and Strain in steel:

Bending is a process by which a metal can be deformed by plastically

deforming the material and changing its shape. The material is stressed beyond

the yield strength but below the ultimate tensile strength. Roll forming, [also

known as roll bending], is a process for forming plates, sheets, bars, beams,

angles or pipes into various shapes by passing the work piece between the

properly spaced rolls. Sheet and plate are the mill products often formed by the

roll bending process. Because of the elastic plastic behaviour of the sheet

material, deformation imposed on the sheet when it is forced to conform to the

rolls, has both elastic. The plastic part of the deformation is permanent and it is

not recovered when the sheet is unloaded by removing it from the roll system.

The elastic part of the deformation is recovered up on removal of the load. This

phenomena is known as “spring back” or elastic recovery

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Fig 8.2 Stress and Strain Curve for Steel

3.3 Plastic Theory of Bending:

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(a) Fully elastic state(b) partially plastic state (c) fully plastic state

Fully Plastic Rectangular Section:

For the rectangular section of width b and depth d

the plastic moment of the resistance of plastic hinge can easily be found. The

total loads above and below the neutral axis NA are both equal to in magnitude

but opposite in direction. Further each of these loads acts at a distance d/4 from

the neutral axis. Thus at plastic hinge, the plastic moment of the rectangular

section

3.4 Design Calculation:

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8.3 Geometrical analysis

FORCE ANALYSIS:

The material selected for analysis is mild steel. The mild steel plate

Properties are

Young’s Modulus, E=207GN/

Elastic limit (yield stress) =515MN/

Poisson’s ratio=0.34

Given data from the specification of the machine

The plate thickness t=1mm

Upper roller diameter, du=50mm

Lower roller diameter dl=50mm

Lower rolls centre distance 2f=120mm

Theplate rolling speed v =5.5m/s

Using a geometrical analysis based on the assumption that the

deflected form of the plate is an arc of a circle and this analysis is used to

predict the upper roll vertical force, the torque required for bending and other

requirements

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=

K=0.048m

= =0.0863m

To find the shift of contact angle(θ) of bend plate with rolls:

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=

To find the length:

l=0.0824m

The deflection of the plate below its support point is calculated by taking the

ratio of length square to eight times internal radius

=

=0.017m

The plate will undergo elastic spring back after the maximum bending moment

has been applied. The relaxed radius, after spring back, of the plate may be

determined from the following equation.

M=

M = =66.89 Nm

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I= = =3.333

=9.704m

= =0.863+0.0005=0.8635m

1.872m

0.534m

Upper roll vertical force applied on the plate (Pv)

tan

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VPM

66.89=

257.59N

The lower rolls force to drive the plate is

=195.14N

The side thrust force on the plate is

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=195.14 146.60N

Power required for driving the machine:

P= = =2.69kw

The torque required to roll the plate is calculated:

T= = 3131.55N-mm

Shaft diameter:

For greater strength 45c8 (steel) is common for shafts

Syt = 580

Sut = 770

Using maximum shear stress theory of failure:

=

=

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= 35rpm

For roller speed of 35rpm & with 2.69kw

= =7.33 N-mm

=1.5, =1

= 0.3syt = 0.3(580) = 174N/mm2

= 0.18sut

= 0.18(720) = 138.6N/mm2

Taking the min value of 138.6 N/mm2

=

d=47.97mm let d be 50mm (standard)

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4.SYNOPSIS

In Sheet Metal working industry a wide range of power and

hand operated machines are used. As the sheet metal industry is a large and

growing industry different type of machines are used for different operations.

Our project the sheet metal rolling is very simple in operation by using roller

which is coupled with handle. This machine produces cylindrical objectives of

different diameters. This machine can be used in various fields. This machine

consist of three roller which is coupled with a handle and connecting the handle

shaft with worm shaft. This machine is simple in construction and working.

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5.APPLICATIONS

Sheet Metal rolling machine is used to make,

Outer cylindrical casing for motors employed in submersible

pumps.

Hydraulic and pneumatic cylinders

Bodies of shells and condensers

Dairy equipment

Compressors storage tanks etc…

It is also used to make cylinders of different diameters

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5.1 ADVANTAGES

Operation of this machine is very simple

Unit is compact so less space is required

No hand tools are required

Cylindrical shaped objects of dia 50mm to 225mm can be

produced

The dia can be easily operate this machine

The machine is hand operated. So the cost of the finished

product will be less.

The total cost of the machine is less.

Maintenance of this machine is very easy.

Easy to handle

Less effort & productive

Easy to install at any were

Skilled workers are not required

Convenient for mass production

Less in weight

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5.2 DISADVANTAGES

This machine has a hand operated one

Production time is high.

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6 .ESTIMATION AND COST ANALYSIS:

SL.NO NAME OF MATERIALS QUANTITY AMOUNT1.2.3.4.5.6.7.

Steel Hollow ShaftSteel Square PipeBaseNut and BoltBearingWelding WorkCutting Work

3 2 1 6 6

TOTAL

30001000100020080010001000

8000/-

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