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है”ह”ह

IS 5702 (1970): Flat Thread Rolling Dies [PGD 32: Cuttingtools]

UDC 621.k-7 ( First Reprint MAY 1976)

Indian Standard

SPECIFICATION FOR FLAT THREAD ROLLING DIES

I. Scope-GCpvers terminology, thread dimensions and requirements of flat dies used fbr producing screw threads conforming to IS :4218 (Part Ill)-1967 ‘ IS0 metric screw threads: Part Ill Basic dimensions for design profile’ by rolling. The dimensions of thread form are specified only for Grade I dies.

I.1 Useful information for the users of these dies on the process of thread rolling is given in Appendix A.

2. Terminology - (see also Fig. I and 2).

2. I Back Face-The face opposite to the die face. A duplex die has no back face.

2.2 Bottom face- That on which the die rests in its working position.

2.3 Clamping Angle-The angle between the back face and the end of the die. On a duplex die there are two clamping angles on each end.

2.4 Die Depth--The depth of the threaded face.

2.5 Die Fuce-That an which threads have been produced, that is the threaded face. two die faces.

A duplex die has

2.6 Die length -- The length of the threaded face.

2.7 Die Thickness-The dimension from the die face to the back face of the die. On duplex die the thickness is the dimension between the two threaded faces.

2.8 Helix Angle-The angle whose tangent is obtained by the division of the linear pitch by the circum- ference of the nominal pitch diameter of the thread being produced.

2.9 Lead-in, Run Off-The tapers on the starting and leaving ends respectively, of the stationary die in its working position.

2. IO Optimum Form of Thread -- The basic form with the addition of the allwnce for wear.

2.1 I Pitch Line-The line which, in principle, corresponds to the simple pitch diameter of the thread being formed.

2.12 Top Face-The marked face which shall be uppermost in the machine.

3. Grades

3.1 Grade I -Dies having thread form finished by grinding and capable of producing rolling threads conforming to tolerance quality ‘medium’ according to IS:4218 (Part IV)-1967 ‘IS0 metric screw threads: Part IV Tolerancing system’.

3.2 Grade Z- Dies having thread form finished by any process other than grinding, and capable of producing rolling threads conforming to tolerance quality ‘coarse’ according to IS: 4218 (Part IV)- 1967.

3.2.1 The dimensions of thread form for Grade 2 dies shall be as agreed to between the purchaser and the manufacturer.

t

INI)IAN STANDARDS INSTlTUTtOU MAN&K EMVAN. 9 BAlMOUR SHAH ZAFAR HAM;

NEW DELHI llOOR2 \

A , _

ISrS702- 1970

CLAMPING ANGL

DIE THICKNESS

OR SYMBOL

SIZE AN0 TYPE

STATIZNARV DIE

CREST RAOIUS

SECTION AT 90” TO

MOVING DtC BOTTOM FACE

FIG. I FLAT THREAD ROLLING DIES, SINGLE FACE

COMPONENT WE DIES

-TOP FACE

AND TYPE THREAO

‘-“4FER+ I- r/TOP FACE

-y_(- UFI IX . -_... ANGLE MOVING DIE

SECTION AT !#I” TO BOTTOM .FACE

WG. 2 SLAT THREAD ROLLINC DIES, DUPLEX FACE

2

IS: 5702 - 1970

4. Thread Dimensions for Grade I Dies for IS0 Metric Screw Threads

rc r0

Thick Line indicates Basic Profile

All dimensions in millimetres.

Pitch / I

Hti ht ~ of

Crest Tolerance on Maximum ! Dimen- /

Root Tolerance on Tolerance Dimen- Crest Dimen- Root ( Manufac- on Flank

~ Funda- sion sion to sion turer’s Toie- ~ mental

XZc) Wear Manufac- crest ( Basic

Angie rance )

Tri- aiiow- turer’s angle ante toie-

Profile ) --

rance

P H B C D K 1 A E F __- ____- .

0.35 0.303 0101 0.010 0~010 0.111 0.1 I4 o*oio 0.012 &I” 20’ Es 0.390 0.346 0.115 0.130 0012 o*ois 0.010 8012 0.127 0.145 8130 ::14 0.012 *I” IO’

@I46 * O~Oi2 1 fi0

i:t 0.433 8520 0.606 o-173 0.202 0.144 0.017 0.017 0.020 0.012 0012 OLOi2 0.161 0.222 0.190 0.195 0.227 0.162 0.012 0.012 0.012 0.012 8012 0.012 zti” f *lo 50’

0.75 0.650 0.217 0.020 0.012 0.237 0,012 0.012 0-B 8693 0.23 I 0.020 0.012 8251

zz . 0.012 0.012

2 ::< I 0866 0.289 0.025 0.012 0.314 0.325 0.012 0.012 f 40:

1::’ I.299 I *OB3 0.361 8433 0.028 0.030 0.012 0.017 0’463 0.389 0.487 0406 0.015 O*OlS 0.012 0.012 2 2’ I -75 I.516 0.505 0.033 0.017 0.538 0.568 0.017 8012 f 40:

i.5 2.165 I.732 0.577 z:: *

0.036 0.038 8% * 0.613 8760 0.650 0.812 0.020 0.022 8’:;: * 2 :: 3 2598 0’043 0.025 0.909 0.974 0.025 0.012 f 30:

3.5 3.03 I I.010 0.048 0.025 I *OS8 I.137 0.027 0.012 f 30’ 4 3464 I*155 0.050 0.025 I *205 I.299 0.030 o-012 f 30

Note I -The tolerances in this table refer to single depth of threads only.

Note 2 - The profile of threads on flat thread roiling dies shown has flat root,. Rounding of root shall be permitted as long as the crests of external threads produced by those dies lie within the iimlting profiles shown in Fig. 3 of IS: 4218 ( Part I )-I967 a IS0 metric screw threads : Part I Basic and design profiles ‘.

3

IS : 5702 - 1970

5. Tolerances

SI No. Elements to be Checked Grade I Grade 2

- _____--

I Flatness of Back Face Across the face 0.02 mm 0.04 mm and Bottom Face Along the length up to I50 mm 0.04 mm 804 mm

,! ,, $1 above 150 mm 0.04 mm 0.06 mm

2 Flatness of Die Face Checked with straight edge or surface plate 0.02 mm 084 mm at right angles to face

3 Parallelism of Back a) Along the length of the die 0.05 mm 0, IO mm Face and Die Face

b) Across the depth up to 25 mm 0.013 mm 0.02 mm Above 25 mm up to 50 mm 0.02 mm -084 mm Above 50 mm up to 100 mm 8.04 mm 0.05 mm Above 100 mm up to 150 mm 0.05 mm 0.08 mm

4 Parallelism of top and bottom faces per 25 mm of die length and thickness 0.013 mm 0.013 mm

5 Deviation on die thickness + 0.4 mm + 0.4 mm

- -l__-_.l__

6 Helix Angle* f 2’ f 3’

___~_

7 Pitch?, Cumulative pitch per 25 mm die depth f 0.013 mm f 002 mm

8 Clamping Angle -f- I” + 1”

In case of square end dies:

a) Squareness of clamping angle with bottom face, per 25 mm of die depth

b) Squareness of clamping angle with back and bottom faces per 25 mm of die thickness and depth respectively

084 mm 084 mm

0:04 mm 0.04 mm

Note-In case of duplex dies, one of the faces shall be considered as back face.

*The helix angle error of each die of every pair shall be in the same direction as that of the mating die, that is, if the helix angle error of one of the pair is plus, then that of the other shall also be plus; conversely for the minus condition.

t The pitch error of each die of every pair shall be in the same direction as that of the mating die, that is, if the pitch error of one of the pairs is plus, then that of the other shall also be plus; conversely for the minus condition.

_-~ ._

6. Marking-The top face of each die shall be marked legibly and indelibly with the nominal diameter of thread, matching number or symbol and the manufacturer’s name or trade-mark.

7. ISI Certification Marking-Details available with the Indian Standards Institution, New Delhi 2.

4

IS : 5702 - 1970

APPENDIX A

(Clause 1.1)

USEFUL INFORMATION FOR USERS OF FLAT THREAD

ROLLING DIES

A- I. Introduction

A-l.1 If flat dies complying with this standard are used in thread rolling machines in reasonable condition, threads can be produced, without difficulty at a high rate to meet Indian standard thread specifications. There are, however, some points not covered in the dimensional portion of this specification which should be taken into consideration if really satisfactory production is to be achieved.

A-l.2 No attempt will be made here to survey the vast amount of data accumulated as a result of research over many years. For those interested there are many technical articles on the subject, dealing with such aspects as penetration forces, penetration rates, geometric blank forms (non-circularity), die mate- rials, special flat die machines, etc. thread rolling practice.

These, however, are for the specialist and are not essential to good

A-l.3 In this specification reference is made to the chamfer at the top and bottom of the die faces, and the ‘ lead-in’ and ’ run-off ‘. Owing to functional differences in the various types of flat die machines, no attempt has been -made to restrict these elements by specifying dimensions. It is the object of this appendix, however, to give some guidance not only on these points, but also on such subjects as prepara- tion of the blank before rolling, matching of the dies, thread form, die material and suitable heat treat- ment, and materials which can be rolled satisfactorily.

A-2. P’roparation of the Blank-The diameter of the blank before rolling should approximate to the required pitch diameter and should be hejd within limits of tolerance necessary to ensure that the finished thread is within the permissible tolerance. ‘Out-of-roundness’ must be controlled, because ovality on any geometric.form will not be entirely eliminated by flat die rolling. When oversize blanks are used, oversize threads will result; any attempt to reduce the pitch diameter by closing in the dies is likely to result in burst blanks and damaged dies. Undersize blanks will result either in undersize effective diameters, or undersize major diameters, or both, according to the setting of the machine. Although not essential, the end of the blank should be chamfered at 90” included angle or, better still at 60”. This chamfering or pointing not only gives a better appearance, but reduces wear on the dies. It is, however, quite satisfactory to omit this chamfering or pointing on the blank, as the rolling .operation gives a natural lead to the thread; this fact is recognized in specifications for bolts and screws.

A-3. Matching the Dies

A-3.1 A pair of dies should be so matched that the crests of the threads of one die are opposite to the roots of the threads of the other die at the point where the blank starts to roll. As this point varies for different makes of machine, it is not possible to lay down any hard and fast rule. Generally, however, matching is effected by the die manufacturer, by machining the thread on one die at a certain position on the machine table, and moving the mating die a controlled distance so that matching is assured at the desired point. This point may approximate to the leading edges of the die, or to a point further back in cases where the starting finger pushes the blank between the dies.

A-3.2 Obviously the care exercised by the die manufacturer in producing dies will be nullified if the dies are not set up properly in the machine. As already mentioned, different methods are used on different makes of machines to start the blank rolling at the correct point along the die faces; it is not possible, therefore, to include details on setting methods. Whatever method is used, however, a check should be made &fore running the machine to see that the dies are properly matched. If a blank is placed between the dies and the machine pulled over by hand so that the blank rotates through 180” the tracks marked on the blank by the crests of the threads on both dies should coincide; if these do not, the dies are mismatched and need resetting.

A-4. Thread Profile

A-4.1 Inevitably this depends on the specification for the thrrds to be rolled. In special cases full threads with accurate radii at crest and root may be requfred for gas or water-tight joints. In general, however, the tliread profile on the die should be such that maximum die life is obtained consistent with s t R ecification

reads) requirements. As the crest of the threads on the die (producing the root of the rolled

is subject to most wear, this skutd be made with a positive margin, bearing in mind that this should not be so large as to result in an undersize minor diameter if the rolled thread is at the minimum pitch diameter.

A-4.2 When producing the threads cm the rolling die, the thread angle should be compensated, but as the amount of compensation is small, it is considered unnecessary to make this adjustment for general work.

5

1S:5702-1970

A-5. Chamfer at Top and Bottom Edge

A-5.1 ‘Chamfer’, in this specification, requires the removal of the sharp edges at the top and bottom of the die faces as needed to suit the particular application. Some chamfering is essential in order to remove the feather edge caused by the angular milling or grinding of the thread, but the amount varies with the circumstances. Generally, a chamfer of 45”, almost the full depth of the thread (from 66 per- cent to 75 percent) is satisfactory.

A-5.2 If a rather long ‘run-out’ (imperfect thread) is permissible on the threads to be roiled, an angle of 60” to the top face is advantageous, as th.is will assist in preventing chipping of the end threads of the die.

A-6. ‘ Lead-in ’ and ‘ Bun Off’

A-6.1 ‘Lead in and run off’ also depe!d on the type of machine in which the dies will be used. Where no starting finger is employed the amount of ‘lead in’ shall be very short. If a machine has the usual ‘U’ section bed, without tie bars at the open end of the ‘ U’, a relatively short ‘ lead in’ is adequate. ‘if tie bars are used, preventing the ‘give’ associated with an open ‘ U’ from, then a much longer ‘ lead in’ is necessary; this may be as much as two-thirds of the length of the stationary die.

A-6.2 The ‘run off’ is machined to prevent ‘ nipping’ of the blank as it leaves the die; for normal work it may be the same as the ‘lead in’.

. . -

A-7. Material for Fiat Rolling Dies

A-7.1 The analysis of the material from which the dies are manufactured is of prime importance. steel or high speed steels are normally used, heat-treated to 700 HV to 800 HV (60 HRC to 64 HRC).

Alloy

A-7.2 Foruse on brass or other ductile non-ferrous material, or on low-tensile steel, a plain carbon steel is considered suitable on some occasions.

A-7.3 The material for dies which are to have a ground finish should be free from piping inclusions or segregations, as any of these disclosed on the die face would be disastrous to the whole operation. The cleanliness of the material is, of course, important on ail types of these dies. Typical materials from which dies are regularly made are:

a) chrome non-shrink tool steel (air-hardening),

b) high speed steel (oil- or air-hardening), and

C) one percent carbon steel (water hardening).

A.#. Materials Which can be Rolled Satisfactorily

A4.1 Most steels and many non-ferrous materials can be thread-roiled without difficulty. The operation can be applied to heat-treated high-tensile steels up to 100 to I IO kg/mm2 but in such cases die life is considerably reduced. it is possible to roil steels of even higher tensile strength with flat dies, but the economics of the process scarcely warrant the attempt. in cases where heat-treated materials with a tensile strength approaching I25 kg/mm2 are roiled the root of the thread on the component is increased in hardness by cold working to a figure approaching the hardess of the die itself. it is more economical, therefore, to roil in the annealed condition and heattreat to.give the required tensile strengh. When components are roiled in the heat-treated condition which is sometimes essential, care should be taken to carry this out on a s&ciently robust machine with a die length which will ensure at least seven revolution of the workpiece.

A-8.2 Free-cutting brass tends to be difficult for roiling unless the pitch is relatively fine, because the material is fikely to break down. There are, however, special brasses of high copper content which can be thread roiled very easily.