Dies for making self-locking screws and method of making same

Claim 2

A thread rolling die for rolling self-locking threads on a screw, said die having an overall configuration of a plurality of parallel threads adapted to form corresponding threads on a cylindrical work piece and having at least one integral thread in which a portion of the flank of said thread is cut and deformed significantly along a path parallel to the thread crest away from its normal flank configuration to form a rib extending outwardly beyond said flank and a cavity in said flank coextensive with said rib.

Claim 3

A thread rolling die for rolling self-locking threads in a screw, said die having an overall configuration of a plurality of parallel threads adapted to form corresponding threads in a screw, said die having at least one thread which is an integral part of said die in which a portion of the flank of said die thread adjacent the root of said thread is cut and deformed away from its normal flank configuration to produce a tapered rib and an adjacent cavity in said flank, the face of said deformed portion that was cut from said flank being moved transversely until it is placed in engagement with part of the flank material of the next Laterally adjacent die thread.

Claim 4

A thread rolling die for rolling self-locking threads in a screw, said die having an overall configuration of a plurality of parallel threads adapted to form corresponding threads in a screw, said die having at least one thread which is an integral part of said die in which a portion of the flank of said die thread adjacent the root of said thread is cut and deformed away from its normal flank configuration to produce a tapered rib and an adjacent cavity in said flank, the face of said deformed portion that was cut from said flank being moved transversely until it is placed in engagement with part of the flank material of the next Laterally adjacent die thread.

Claim 5

A thread rolling die for rolling self-locking threads in a screw, said die having a plurality of parallel threads whose operative crests and roots are undeformed throughout their length and at least one thread of said die having at least one straight rib paralleling throughout the major portion of its length the crest of said one die thread and extending outwardly from the flank of said one die thread and being intermediate the crest and root of said one thread, the said rib having inner and outer walls intersecting at an acute angle, the inner wall commencing at a position interiorly of said flank thereby to form a cavity in said die thread flank, the said rib being adapted to form a cavity in the flank of a screw thread when said thread is rolled under sufficient pressure against and past the said rib, and the said cavity in the flank of said die thread is adapted to receive material displaced from said screw thread by said rib.

Claim 6

A thread rolling die for rolling self-locking threads in a screw, said die having a plurality of parallel threads whose operative crests and roots are undeformed throughout their length and at least one thread of said die having at least one straight rib paralleling throughout the major portion of its length the crest of said one die thread and extending outwardly from the flank of said one die thread and being intermediate the crest and root of said one thread, the said rib having inner and outer walls intersecting at an acute angle, the inner wall commencing at a position interiorly of said flank thereby to form a cavity in said die thread flank, the said rib being adapted to form a cavity in the flank of a screw thread when said thread is rolled under sufficient pressure against and past the said rib, and the said cavity in the flank of said die thread is adapted to receive material displaced from said screw thread by said rib.

Claim 7

A thread rolling die as set forth in claim 3, said die rib having an inner wall commencing at a point inside said die thread flank and an outer wall commencing at said die thread flank, said intersection of said outer wall and said inner wall forming an edge parallel to said die thread crest.

Claim 8

A thread rolling die as set forth in claim 3, the length of said die rib effectively in engagement with said screw thread being not more than the 360* circumferential length of the rib to be formed in the screw thread.

Claim 9

A flat thread rolling die having a vertical face with die threads therein, at least one flank of one thread of said die having at its finishing end a rib and cavity paralleling the crest of said thread, said die rib shaped so as to be capable of creating in the flank of a screw thread rolled thereagainst, a complementary rib and cavity, all said die threads that do not have ribs therein being relieved at their finishing ends in such manner that their crests, roots and flanks curve away from the normal vertical plane of the face of the die, and all die threads having said ribs therein being relieved to a greater degree than those die threads without ribs therein.

Claim 10

A flat thread rolling die having a vertical face with die threads therein, at least one flank of one thread of said die having at its finishing end a rib and cavity paralleling the crest of said thread, said die rib shaped so as to be capable of creating in the flank of a screw thread rolled thereagainst, a complementary rib and cavity, all said die threads that do not have ribs therein being relieved at their finishing ends in such manner that their crests, roots and flanks curve away from the normal vertical plane of the face of the die, and all die threads having said ribs therein being relieved to a greater degree than those die threads without ribs therein.

Claim 11

A pair of relatively movable dies for producing screws with self-locking ribs thereon, said dies having a plurality of parallel threads whose operative crests and roots are undeformed throughout their lengths, one or more of the threads of one of the dies having ribs intermediate the said crests and roots, said ribs paralleling said crests and extending along the flanks of said threads near the discharge end of said die for creating ribs in the threads of each successively created screw during at least part of the last 360* of rotation of said screw, the terminal ends of the threads of the other die being formed to receive the ribs created in the screw by the said one die without causing deformation of said screw thread ribs over the major portion of their circumferential lengths, whereby each of said screws produced by said dies will be discharged from said dies with the said screw thread ribs unchanged from the configuration created by said one die over at least the major portion of their circumferential lengths.

Claim 12

A pair of relatively movable dies for producing screws with self-locking ribs thereon, said dies having a plurality of parallel threads whose operative crests and roots are undeformed throughout their lengths, one or more of the threads of one of the dies having ribs intermediate the said crests and roots, said ribs paralleling said crests and extending along the flanks of said threads near the discharge end of said die for creating ribs in the threads of each successively created screw during at least part of the last 360* of rotation of said screw, the terminal ends of the threads of the other die being formed to receive the ribs created in the screw by the said one die without causing deformation of said screw thread ribs over the major portion of their circumferential lengths, whereby each of said screws produced by said dies will be discharged from said dies with the said screw thread ribs unchanged from the configuration created by said one die over at least the major portion of their circumferential lengths.

Claim 13

A pair of dies as set forth in claim 7 and means on the said other die for fairing the leading end of said screw rib back against its flank prior to discharge of said screw from said dies, and means on said other die for causing gradual separation of each said screw thread flank from its said die rib thereby to gradually diminish the said screw rib at its trailing end from maximum to zero immediately following the said fairing of the said leading end by said other die.

Claim 14

A pair of dies for producing self-locking screws, one of said dies being relatively movable with respect to the other of said dies, some of the threads of one of the dies having ribs extending along the flanks of said threads near the discharge end of said die for creating corresponding ribs in the threads of the screw during not more than the last 360* of rotation of said screw, the terminal ends of the threads of the other die being relieved in the following manner: The crests and roots and flanks therebetween of the threads curving away from said one die, whereby as a rib on the screw threads is created by a rib on said one die, the leading end of said screw thread rib after 180* of rotation is engaged first by an unrelieved wall of the corresponding thread of said other die and then progressively by the relieved wall of the thread of said other die and caused to assume a tapered form, and said screw, due to said relieved threads on the said other die, moves correspondingly away from the said one die to cause continuous decrease in the depth and width of the screw thread rib of the trailing end thereof.

Claim 15

A pair of dies for producing self-locking screws, one of said dies being relatively movable with respect to the other of said dies, some of the threads of one of the dies having ribs extending along the flanks of said threads near the discharge end of said die for creating corresponding ribs in the threads of the screw during not more than the last 360* of rotation of said screw, the terminal ends of the threads of the other die being relieved in the following manner: The crests and roots and flanks therebetween of the threads curving away from said one die, whereby as a rib on the screw threads is created by a rib on said one die, the leading end of said screw thread rib after 180* of rotation is engaged first by an unrelieved wall of the corresponding thread of said other die and then progressively by the relieved wall of the thread of said other die and caused to assume a tapered form, and said screw, due to said relieved threads on the said other die, moves correspondingly away from the said one die to cause continuous decrease in the depth and width of the screw thread rib of the trailing end thereof.

Claim 16

A pair of dies as set forth in claim 9, the said ribs on said one die including inner and outer walls, each said inner wall commencing within the flank of its thread and each said outer wall commencing at the flank of its thread, said walls intersecting to form an edge capable of penetrating the flank of a screw thread when the latter is rolled between said dies and engaged by said rib.

Claim 17

A pair of dies for rolling threads on a cylindrical workpiece and means on said dies for creating a continuous rib on one flank only of one or more pitches of said screw threads after said threads have been substantially fully formed by said dies, said means comprising on each said die a rib extending outwardly beyond one flank only of at least one thread of each said die near the discharge end of each said die, said rib configuration being such as to be capable of creating a complementary rib in the flank of said substantially fully formed screw thread when the workpiece moves through the latter part of its travel between said dies, said die ribs so located on their respective dies that when the said ribs of both dies are opposite each other during the threading operation, the axis of the workpiece will be transversely between said die ribs and the said die ribs at their points of engagement with said screw thread flank will be one-half pitch apart axially of said workpiece whereby after the workpiece has made one-half a revolution about its axis between said opposed die ribs while the die ribs are simultaneously and progressively engaging the flank of said screw thread at positions 180* apart, there will have been formed at least one continuous 360* rib on one flank of said screw thread for one full pitch.

Claim 18

A pair of dies for rolling threads on a cylindrical workpiece and means on said dies for creating a continuous rib on one flank only of one or more pitches of said screw threads after said threads have been substantially fully formed by said dies, said means comprising on each said die a rib extending outwardly beyond one flank only of at least one thread of each said die near the discharge end of each said die, said rib configuration being such as to be capable of creating a complementary rib in the flank of said substantially fully formed screw thread when the workpiece moves through the latter part of its travel between said dies, said die ribs so located on their respective dies that when the said ribs of both dies are opposite each other during the threading operation, the axis of the workpiece will be transversely between said die ribs and the said die ribs at their points of engagement with said screw thread flank will be one-half pitch apart axially of said workpiece whereby after the workpiece has made one-half a revolution about its axis between said opposed die ribs while the die ribs are simultaneously and progressively engaging the flank of said screw thread at positions 180* apart, there will have been formed at least one continuous 360* rib on one flank of said screw thread for one full pitch.

Claim 19

The construction set forth in claim 1, one of said dies being shorter than the other and having its die ribs and the related die threads relieved at their discharge ends to prevent subsequent deformation of that part of said rib created in the flank of said screw thread by said other longer die.

Claim 20

The construction set forth in claim 11, one of said dies being longer than the other, the upper flank of the thread of the said longer die next above said uppermost die rib acting to fair the leading end of said screw thread rib created by the uppermost rib in said shorter die back into the screw thread flank prior to discharge of said threaded screw from said dies.

Claim 21

The construction set forth in claim 11, the leading ends of the die ribs on both said dies being so positioned on their respective die thread flanks that the said leading ends will substantially simultaneously engage a flank of said screw thread at diametrically opposite positions.

Claim 22

The construction set forth in claim 11, and means integral with said dies for fairing back into the screw thread flank the leading end of the screw thread rib nearest the head of said screw and means for causing the path of the axis of said workpiece to curve away from one of said dies, thereby to reduce progressively the size of the end of said rib most distant from said screw head.

Claim 23

A pair of flat thread rolling dies, each die having conventional dIe threads for rolling conventional screw threads on a cylindrical workpiece, one die being shorter than the other, said shorter die adapted to be the fixed die in a thread rolling machine, each die having on at least one flank of one thread a rib formed from the material of each said flank, said ribs located near the finishing end of its said die so that, as the said rib on said dies pass each other, said workpiece will be therebetween, said ribs so shaped as to be capable of producing a complementary rib on the flank of the thread of a screw rolling between said die ribs, all threads of the shorter die that do not have ribs therein being relieved at their finishing ends sufficiently to prevent a roll off mark from occuring on said screw as the finished screw leaves said dies, and all threads of the shorter die containing said die ribs being relieved at their finishing ends to a greater extent whereby a rib created in the flank of the screw thread by the die rib in the longer die will not be adversely affected by the die threads at the finishing end of said shorter die.

Claim 24

A pair of flat thread rolling dies, each die having conventional dIe threads for rolling conventional screw threads on a cylindrical workpiece, one die being shorter than the other, said shorter die adapted to be the fixed die in a thread rolling machine, each die having on at least one flank of one thread a rib formed from the material of each said flank, said ribs located near the finishing end of its said die so that, as the said rib on said dies pass each other, said workpiece will be therebetween, said ribs so shaped as to be capable of producing a complementary rib on the flank of the thread of a screw rolling between said die ribs, all threads of the shorter die that do not have ribs therein being relieved at their finishing ends sufficiently to prevent a roll off mark from occuring on said screw as the finished screw leaves said dies, and all threads of the shorter die containing said die ribs being relieved at their finishing ends to a greater extent whereby a rib created in the flank of the screw thread by the die rib in the longer die will not be adversely affected by the die threads at the finishing end of said shorter die.

Claim 27

The method set forth in claim 17, said cutting being done by rolling the screw thread flank against said tool surfaces under sufficient pressure against the opposite side of said screw to hold the path of the screw axis parallel to the edge of the said tool.

Claim 28

The method set forth in claim 18 and after said screw has rotated approximately 180* from the point of initial engagement with said tool surfaces, applying pressure to the leading end portion of said rib to force the said leading end portion back into said flank in decreasing degree to produce a finished rib that gradually develops outwardly from the said thread flank at the said leading end.

Claim 29

The method set forth in claim 18 and before said screw has been discharged from said dies, progressively decreasing the pressure of said screw against said tool surfaces to gradually decrease to zero the depth of the cut and the size of the rib at the trailing end of said rib.

Claim 30

The method set forth in claim 18 and after said screw has rotated approximately 180* from the point of initial engagement with said tool surfaces, applying pressure to the leading end portion of said rib to force the said leading end portion back into said flank in decreasing degree to produce a finished rib that gradually develops outwardly from the said thread flank at the said leading end, and before said screw has rotated 360* along said tool surfaces, progressively decreasing the pressure of said screw against said tool surfaces to gradually decrease to zero the depth of the cut and the size of the rib at the trailing end of said rib.

Claim 31

The method set forth in claim 17, said cutting into said flank of one pitch being done simultaneously at positions 180* apart by rolling said screw thread flank between oppositely disposed tool surfaces.

Claim 32

The method set forth in claim 22, and thereafter fairing the leading end of the rib produced by said cutting back into the flank from which it was cut.

Claim 33

The method set forth in claim 22, the leading end of the rib produced by cutting the flank on one side merging into the trailing end of the rib Produced by cutting the flank on the opposite side after the screw has rolled through 180* thereby to produce a continuous rib of 360* on one pitch of said screw thread.