US2364442A - Method of rolling threads - Google Patents

Method of rolling threads Download PDF

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Publication number
US2364442A
US2364442A US489639A US48963943A US2364442A US 2364442 A US2364442 A US 2364442A US 489639 A US489639 A US 489639A US 48963943 A US48963943 A US 48963943A US 2364442 A US2364442 A US 2364442A
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United States
Prior art keywords
dies
workpiece
threads
work
respect
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Expired - Lifetime
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US489639A
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English (en)
Inventor
Joseph H Hoern
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Eaton Corp
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Eaton Manufacturing Co
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Priority to US489639A priority Critical patent/US2364442A/en
Application granted granted Critical
Publication of US2364442A publication Critical patent/US2364442A/en
Priority to FR916260D priority patent/FR916260A/fr
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
    • B21H3/00—Making helical bodies or bodies having parts of helical shape
    • B21H3/02—Making helical bodies or bodies having parts of helical shape external screw-threads ; Making dies for thread rolling
    • B21H3/06—Making by means of profiled members other than rolls, e.g. reciprocating flat dies or jaws, moved longitudinally or curvilinearly with respect to each other

Definitions

  • This invention relates to the rolling of screw threads on machine parts such as bolts, screws and the like by means of flat dies and has for its principal obect the provision of a method of rolling threads in' this manner by the practice of which threads may be produced on a part as accurately as has heretofore been possible by grinding operations.
  • Other objects of the invention include the provision of a method of rolling screw threads on .workpieces by means of flat dies including the steps of insuring initiation. of the rolling movement of the work between the dies when the dies are in a predetermined position with respect to each other in the direction of their movement longitudinally with respect to each other, by first efiecting only partial imbedding of the dies in the work and thereafter effecting a complete imbedding ofv the dies in the work; the provision of a method as 'above described in which the final imbedding of the dies in the work is accomplished radually; the provision of a method as above described in which the final imbedding of the dies in the work is accomplished by a bodily shiftable movement of one of the dies laterally with respect to the other thereof; the provision of a method as above described in which the dies are separated from one another prior to the time the workpiece is discharged from between them; the provision of a method as above described in which the dies are initially separated from one another by
  • Still further objects of the invention include the provision of a new and novel method of checking the steps of initially efiecting a partial imbedding of the dies in the work and then checking the alignment of the relatively shallow grooves thus formed in the work; and the provision of a method as herein described in which the alignment of the relatively shallow grooves is checked by the use of an optical projector.
  • Additional objects of the invention include the provision of a method of rolling threads between substantially flat dies in which the dies are moved longitudinally relative to each other at a constant speed whereby to result in better work and longer life of the dies than in accordance with conventional methods; and the provision of a method in which the speed of operation of the dies may be simply varied to enable the highest safe speed of operation to be maintained between the dies and the work commensurate with the hardness of the work and the practical life of the dies.
  • Fig. 1 is a fragmentary, broken and partially sectioned plan view of threadrolling apparatus invention may be carried out, and illustrating a piece of work in operative relation with respect thereto;
  • Fig. 2 is an enlarged fragmentary, plan view of that portion of the apparatus shown in Fig. 1 within the circle 2 thereof;
  • Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 2 and illustrating the work in the position which it assumes with respect to the thread rolling dies at the. moment that initiation of the thread rolling movement .of the dies on the work begins;
  • Fig. 4 is a view similar to Fig. 2 illustrating the use of a modified and preferred form of die structure employed in the method;
  • Fig. 5 is an enlarged, fragmentary sectional View taken on the line 55 of Fig. 4 and illustrating the conformation of the threads of the dies at the advanced ends thereof;
  • Fig. 6 is a more or less diagrammatic view illustrating the manner in which an optical projector is employed to check the accuracy of the alignment of the dies by employing a workpiece in which the dies have been initially engaged only;
  • Fig. 7 is a side elevational view of a typical form of workpiece in blank form.
  • Fig. 8 is a side ⁇ elevational view of the workpiece shown in FigL-7 after it has been threaded.
  • thedies are located laterally with respect to each other at such a distance that when a workpiece is passed between them it will be'provided with threads of the desired pitch diameter, the dies are caused to relatively reciprocate with respect to each other longitudinally thereof and each time the movable diemember is separated from the stationary die member at one end of its stroke the workpiece is fed into position and is gripped between the two die members on the ensuing stroke and acted on thereby to form threads thereon.
  • the principal object of the in-- vention to provide a method by the practice of which the threads of screw threaded parts may be formed by flat dies in such a manner that the accuracy and finish thereof are comparable to the accuracy and finish of threads now produced by grinding and may actually be employed for any use which ground thread parts of extreme accuracy are used.
  • the above objects are obtained bythe use-of flat dies which not only are reciprocable longitudinally relative to each other in the same manner as in conventional methods, but further in which the dies are relatively movable withrespect to each other lat erally thereof. In this connection it is to be:
  • the dies are laterally spaced frdm one another atuthe time the workpiece or' blank is introduced between them by a distance greater than that required to form full depth or complete threads on the blank but by a distance less than the outside diameter of the blank itself, so that when the blank is first gripped between the dies during longitudinal movement of the latter the threads of the dies will'be only partially im bedded in the surface of the blank.
  • This step is for the purpose of insuring rolling of the blank between the two dies the moment it becomes gripped between them, thus insuring against any possible slippage between the blank and the dies.
  • the partial imbedding of'the teeth of the dies in the work preferably conntinues after initiation of the rolling movement of the work blank between the q dies for at least half a turn so that a continuous but partially formed thread is formed in the work blank thereby.
  • the dies are moved, more or less gradually, laterally toward one another.
  • the force exerted by such fluid pressure means is preferably such as to be incapable of completely sinking the threads of the dies into the workpiece while the dies and workpiece are stationary, but is suf ficiently great so that during the continued rolling movement of the workpiece between the dies, the dies are more or less gradually sunk home to their final position.
  • This feature not only provides the gradual sinking of the threads of the dies into the workpiece; but further acts as an aid. in.insuring against slippage between the dies and the workpiece because of such rapid sinking of the dies into the workpiece as to engender danger of slippage between the workpiece and the diesand, therefore. throwing the workpiece out of synchronism with the dies.
  • Fig. 8 a typical screw which may be advantageously formed inaccordance with the method of the present invention. It is to be understood that the screw shown in Fig. 8 is arbitrarily selected from a large class of screws or other threaded elements that may also be advantageously formed in accordance with the present inventionand is selected in this case simply as a matter of illustration. It will be noted that the screw illustrated in Fig. 8 includes a threaded end portion joined at one end to a shank l2 of a diameter preferably slightly less than the root diameter of the threads on the end l2.
  • the shank I2 is enlarged at that end thereof opposite the threaded end l2 as at M to approximately the outside diameter of the threaded end I0 and joins with a concentric disc-like flange IS on the opposite face of which the usual head i8 is formed.
  • the work blank from which the screw shown in Fig. 8 is formed in accordance with the present invention is illustrated in Fig. 7 generally by'the I of the usual V-type, then the diameter of the end ID of the workpiece or blank I will be sub-- stantially equal to the pitch diameter of the threads in the final workpiece.
  • the tolerance or permitted variation of the dimensions in the end H) of the work blank I will, of course, de-
  • the end 10' is of such diameter that the metal thereof will not completely fill the threads of the dies to the very roots thereof for it will be appreciated that if the diameter of the end l0' of the workpiece or blank 1 is so great as to provide more metal than is required to completely maker.
  • the advanced ends of'the dies and 22 in the direction of their relative movement with respect to each other during a working stroke are shown as being square with respect to the plane of the threaded faces thereof, whereas in actual practice it is preferable to bevel oil the outer end teeth of such entering ends of the dies as illustrated in Fig. 4 and as will hereinafter be more specifically. described.
  • the entering end faces of the dies '20 and 22 join with the threaded .faces of the dies through a sharp corner or fill the space between the threads of the dies,
  • a pair of dies illustrated in Figs. 1 to 3, inclusive, at 20 and 22, respectively, are employed.
  • the dies 20 and 22 may be more or less of conventional character having, as illustrated in Fig. 3,
  • - height of the threaded portions of the dies is preferably only slightly in excess of the length of the end 10' of the blank and the dies 20 and 22 are extended upwardly from the threads 24 such a distance, as brought out in Fig. 3, that the flange IS, in resting upon theupper edges of the dies, serves to locate the end I0 in proper relation with respect to the threads 24.
  • the principal difference between the dies 20 and 22 and conventional dies is that preferably the roots of the threads 24 in each die lie in a in points as illustrated in Figs. 1 and 2.
  • the mechanism employed for moving the dies 20 and 22 relative to each other both longitudinally and laterally thereof may be of any, suitable character in accordance with the broadsupported against lateral movement particularly a in a direction away'from the die 22.
  • the head 26 may be caused to reciprocate in any desired manner but, in accordance with a more limited phase of the invention, it is shown as being connected to the piston rod 30 of a piston 32 reciprocably received within a cylinder 34 mounted" upon the machine with its axis parallel to the path of movement of the head 26.
  • the piston 32 is caused to operate in the cylinder 34 by means of fluid and preferablyliquid under pressure introduced through a conduit 36 equipped with a throttle valve 31 to a control valve 38 from which tubes 40 lead to the opposite ends of the cylinder 34 and from which and exhausted-from the opposite end and whenat the opposite end of its movable position the flow of fiuid will be reversed.
  • the crank is ordinarily rotated at the fastest speed possible at which the dies will satisfactorily stand up for a workpiece of average hardness but in such case the speed of relative movement between the dies is either much lower than necessary at the beginning and end of the operation or else it exceeds the safe linear speed between the dies and the work during the central portion of each stroke and which in the latter case is detrimental to the life of the dies. Furthermore, it is extremely difficult, if not impractical, in most cases, to change the speed of relative reciprocation between the dies to accommodate them to work pieces of different hardnesses.
  • a hydraulic cylinder and piston for effecting relative reciprocation between the dies longitudinally thereof it provides a constant speed of the dies relative to one another over the entire stroke and by employing a throttle valve such as 31 controlling the volume of flow through the inlet pipe 36 the relative speed of reciprocation between the dies may be varied so as to maintain the highest safest speed in every case.
  • the speed of reciprocation may be varied by the valve 31 so that the speed of the dies is the fastest practically possible for any given piece of work with due regard to the, life of the dies.
  • the speed of reciprocation ' may be adjusted through the valve 31' to correspond.
  • the'softer the metal the higher the permissible linear speed between the dies and the work, and the harder the material the smaller the linear speed desirspaced relation to each other on the rod 44 co-.
  • the die 22 is, of course, arranged with its threaded face in parallel relation with respect to the threaded face of the die 20 where the threaded endof the screw element to be formed is cylindrical and not tapered, but, of course, tapered where the latter condition obtains;
  • the dies as having parallel faces and/or the blank as having a cylindrical portion to be threaded, it is to be interpreted broadly enough to relate to and to cover a condition wherein the faces of the dies are inclined into conformance with the taper of a tapered part to be threaded and in which that portion of the blank to be threaded is correspondingly tapered.
  • the die 22 is shown fixedto the outer end of a relatively rigid piston or plunger 66 which is reciprocably received within a cylinder 62 rigidly fixed with respect to the bed of the machine and with its axis perpendicular to or substantially perpendicular to the plane of the threaded faceof the die 2i!
  • the die 22 is thus mounted for When workpieces made from diiferent hardnesses of material are being worked upon movement in a direction perpendicular or substantially perpendicular to its threaded face and, therefore, laterally with respect to the die 20.
  • Means are provided for limitin the movement of the die 22 laterally towards the die 20 and this is shown more or less diagrammatically in Fig.
  • Means are also provided for constantly urging the piston 66 inwardly of the cylinder 62, in the present case this beingshown by way of illustration as comprising a pair of. springs disposed on diametrically opposite sides of the cylinder 62 and tensioned between a hook or the like 12 fixed to the rear face of the die 22 and another hook M fixed to the cylinder 62.
  • means are also .provided for limiting the lateral movement of the die 22 away from the die cally shown as consisting of a stop screw 16 threadably mounted in a lug 18 on the side of the cylinder 62 and arranged with its inner end in a position to abut the rear face of the die 22 when the latter has moved laterally away from the die 20 under the influence of the springs 10.
  • the stop nut 66 will be so positioned on the stud 64 as to limit lateral movement of the die 22 towards the die 26 to such a lateral spacing between the dies 20 and 22. as to result in the forming of threads on a work-piece engaged between the dies to the desired pitch diameter, the spacing of the dies 20 and 22 in such position being equivalent to the permanent spacing which these general types-of dies are spaced from one another in accordance with conventional practice.
  • the stop screw 16 will limit lateral movement of the die 22 away from the die 20, in accordance with the present invention, to a distance such that the points of the threads 24 on the dies 26 than the difference between the pitch diameter of the finished piece and the outside diameterof the end portion ID of the work blank or piece.
  • Fig. 1 the die 22 is shown at the outer limit of its reciprocable position as determined by the position of the stop screw 76.
  • the valve 88 is provided with an actuating handle 88 which, when at one extremity of its movable position, connects the tube 88 with the tube 82 and, when at the opposite end of its movable position, connects the'tube 88 with the tube 84.
  • any suitable means may be provided for operating the valve 88 in-timed relation with respect to the longitudinally reciprocable position of the piece at the time the dies first grip it between them is exerted in a plane passing diametrically through the workpiece, thus reducing the tenddie 28.
  • this means comprises a solenoid unit 88 connected by a link 98 to the free end of the operating handle 88 of the valve 88.
  • the solenoid unit 89 is connected in series in an electrical circuit with a conventional switch 92 mounted on the frame of the machine and having an actuating arm 84 positioned in intersecting relationship with respect to the path of movement of the head 28 on the ways 28.
  • the switch 82 is so positioned in the path of movement of the head 28 that the work will be gripped between the dies 28 and 22 while the dies 28 and 22 are at the extreme outer limit of their relative movement in direction lateral to their operative faces before the head 28 engages the switch 82 to connect the tube 82 with the tube 88 and thus move the dies 28 and 22 to the inner limit of the relative lateral movement with respect to each other.
  • the head 28 will pass beyond and become disengaged from the-switch 82, thereby causing the switch 92 to beoperated to disconnect the tube 88 from the tube 82 and connect it to the tube 84 and thereby separate the dies 28 and 22 laterally with respect to each other.
  • This last separating movement of the dies preferably occurs before the work is discharged from between the dies so that the ends of the dies will not mark the work.
  • a reciprocable spring-pressed pusher rod I88 ofconventional construction is preferably provided for forcefully urging the work I8 into position between the dies at the initiation of the rolling operation.
  • the work must begin to roll when the dies are in a predetermined position with respect to each other if the threads formed on the work by the threads of both of the dies are to be exactly helically, aligned with each other and that if, for instance, the work should slip with respect to the dies, even to the slightest extent, the synchronized relation of the threads of the dies and the threads on the work will be destroyed and result either in drunken threads being formed on the work or threads in which the metal of the workpiece is overlapped, thus resulting not only in a weak thread but one which is inherently rough.
  • this locating or positioning means is such as to locate the work midway between the dies at the moment it is gripped between them so as to insure an equal initial imbedding of both dies in the work.
  • a suitable stop is associated with the die 28 so as to limit the position to which the workpiece I may be projected or positioned with respect to the die 28 under the influence of the pusher bar I88 at the initiation of the forming operation.
  • any suitable stop means may be provided for this purpose, in the drawings by way of illustration such stop means comprises a bracket I82 rigidly fixed with respect to either the die 28 or the head 28 and provided with two or more stop screws I84 v vanced ends of the dies 28 and 22.
  • the workpiece in simultaneously engaging the inner ends of the screws I84 and the advanced corner of the die 28, as illustrated in Figs. 1 and 2 in particular, will be limited in its inward movement with respect to the operative face of the die 28.
  • the stop screws I84 are preferably so adjusted that the axis of the workpiece I will be located exactly midway between the opera tive faces of thedies28 and 22 when the dies 28 and 22 are separated laterally to a maximum extent as controlled by the stop screw I8 acting on the,
  • this movement of the die 22 laterally with respect to the die 20 be an instantaneous movement, in fact,, such type of movement is to be avoided inasmuch as any such sudden imbedding would increase the tendency of the Work to slip relative to the dies and increase the tendency of the dies 'to work the metal of the workpiece clear to its center and tend to distort the true section thereof.
  • the movement of the die 22 laterally toward the die 20 is preferably of a more or less gradual nature so as to avoid the tendenciesabove referred to and so that substantially full imbedding of' the teeth of the dies in the workpiece will not occur until the workpiece has rotated to preferably in excess of a complete revolution and preferably from one to three revolutions While pressed between the dies.
  • This more or less gradual inner movement of the die- 22 may be effected in any suitable manner, such as by restricting therate of flow of the liquid from the valve into the cylinder 62, but I have found it preferable, in accordance with a further phase of the invention, to control such movement piston 00 and this is accomplished in the following manner.
  • This same feature is preferably employed in effecting the gradual imbedding of the teeth of the dies 20 and 22 into the workpiece I.
  • the amount of pressure which is applied to the piston 60 once the initial action of the dies on the workpiece iscompleted is such that if the workpiece and dies were stationary, the pressure would be insufficient to effect the complete imbedding of the teeth of the dies into the work but, under the conditions actually existing, the rolling movement of the work between the dies in combination with the pressure employed is sufiicient to effect the substantially complete imbedding of the teeth 24 of the dies into the work during the number of revolutions of the work mentioned.
  • the length of the head 26 is less than the combined length of the dies 20 and 22 so that the operative end 94 of the switch 92 will drop off the head 26 during an operative stroke of the latter before the workpiece is discharged from the ends of the dies, this separation of the dies 20 and 22 under such conditions relieving the pressure of the dies on the work and eliminating the possibility of any such marking.
  • the pressure which is initially exerted by the dies upon the work is at substantially exactly diametrically opposite points which thus exerts a maximum tendency of the dies to rotate the work and aids in preventing possible slippage between the dies and the work.
  • the method of rolling such threads in accordance with the present invention provides a method by means of which the accuracy of the setting of the dies may be checked in-a quick and accurate manner so that, if inaccuracies are thus found, the relative positions of the dies may be varied to overcome the same.
  • this further phase of the present invention when a new set of dies is applied to a machine and it is desired to check work blank such as 1 is introduced between the vdies and a partial rotation thereof is eifected,
  • the hair line I22 falls in such location, it will indicate that the dies are not properly aligned with each other and the offsetting of the hair line with respect to its proper position in either of the cases mentioned will indicate in which direction one of the dies must be adjusted with respect to the other to 'correct the inaccuracies.
  • One of the dies may then be adjusted in accordance with conventional practice or otherwise with respect to the other thereof to overcome such inaccuracies, the operation may be repeated upon another workpiece and re-checked to determine the accuracy of the adjustment, and such checking and rechecking continued until the final accurate location of one of the die members with respect to the other is definitely established.
  • the blank I may be shifted axially until the groove or thread at the opposite side of the blank is aligned with the hair line I22, and the amount of this shifting movement measured accurately by a micrometer or other reading. This will indicate exactly the amount which one die must be shifted vertically with respect to the other'to obtain the required synchronized positions of the dies and aids in eliminating trial. and error methods of attaining the desired results.
  • the method of checking the dies for synchronism with each other comprising the steps of locating the operative faces of said dies laterally with respect to each other by an amount less than the diameter of the workpiece and greater than the lateral spacing between said dies required to form completed threads upon the workpiece, rolling said workpiece between said dies to form partial threads in the workpiece by each of the dies over a substantially no more than half of the circumference of said workpiece, inserting said workpiece in an optical projector, lining up the partial threads formed by one of the dies with a line of the projector perpendicular to the axis of the workpiece, then visually determining the accuracy of location of the partially formed thread on said workpiece produced by the remaining die thereon with respect to said line, and then adjusting at least one of said dies to correct any error thus determined.

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  • Mechanical Engineering (AREA)
  • Forging (AREA)
US489639A 1943-06-04 1943-06-04 Method of rolling threads Expired - Lifetime US2364442A (en)

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US489639A US2364442A (en) 1943-06-04 1943-06-04 Method of rolling threads
FR916260D FR916260A (fr) 1943-06-04 1945-09-14 Perfectionnement aux procédés de laminage des filetages

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2967444A (en) * 1955-06-03 1961-01-10 Rockford Machine Tool Co Thread rolling machines
US3069960A (en) * 1957-03-07 1962-12-25 Elastic Stop Nut Corp Screw threaded member
US3160034A (en) * 1961-01-12 1964-12-08 Imp Wire Products Inc Bolt threading machine
US3183697A (en) * 1962-01-02 1965-05-18 Michigan Tool Co Locating fixture
DE1272265B (de) * 1960-07-19 1968-07-11 Hartford Special Machinery Co Werkstueckzufuehrungsvorrichtung an einer Gewindewalzmaschine mit Walzbacken
US4712410A (en) * 1983-01-17 1987-12-15 Anderson-Cook, Inc. Method and apparatus for cold sizing a round workpiece having multiple diameters
US20150266083A1 (en) * 2012-10-02 2015-09-24 Illinois Tool Works Inc. Method and apparatus for cold forming thread rolling dies

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2967444A (en) * 1955-06-03 1961-01-10 Rockford Machine Tool Co Thread rolling machines
US3069960A (en) * 1957-03-07 1962-12-25 Elastic Stop Nut Corp Screw threaded member
DE1272265B (de) * 1960-07-19 1968-07-11 Hartford Special Machinery Co Werkstueckzufuehrungsvorrichtung an einer Gewindewalzmaschine mit Walzbacken
US3160034A (en) * 1961-01-12 1964-12-08 Imp Wire Products Inc Bolt threading machine
US3183697A (en) * 1962-01-02 1965-05-18 Michigan Tool Co Locating fixture
US4712410A (en) * 1983-01-17 1987-12-15 Anderson-Cook, Inc. Method and apparatus for cold sizing a round workpiece having multiple diameters
US20150266083A1 (en) * 2012-10-02 2015-09-24 Illinois Tool Works Inc. Method and apparatus for cold forming thread rolling dies
US10369618B2 (en) * 2012-10-02 2019-08-06 Illinois Tool Works Inc. Method and apparatus for cold forming thread rolling dies

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Publication number Publication date
FR916260A (fr) 1946-12-02

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