US3439518A - Toolholder for thread rolling tools - Google Patents

Description

A ril 22, 1969 H. c. BURNETT 3, 8

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8, 1967 Sheet -of :5

5; ,4/ FTEEEQETLJJ 7 /2 4 4/1N 4 4} 1 L I 1 44 4 31;. LE. 14,, 2

If ,r I 7 A r Zn? %z:mz1

April 22, 1969 H. c. BURNETT 3,439,518

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8, 1967 Sheet L of s .lEl.

INVENTOR.

BY VA. 7/)

flrratyzKi April 22, 1969 H. c. BURNETT 3,439,518

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8. 1967 I Sheet 3 of s INVENTOR.

BY /W% i% afraid/1% United States Patent 3,439,518 TOOLHOLDER FOR THREAD ROLLING TOOLS Herbert C. Burnett, Fraser, Mich., assignor to Detroit Tap and Tool Co., a corporation of Delaware Filed Feb. 8, 1967, Ser. No. 614,658 Int. Cl. B21b 1/10; B21h 3/04; B21d 17/00 U.S. Cl. 72-101 Claims ABSTRACT OF THE DISCLOSURE This application discloses a thread rolling toolholder having a two piece, pivoted base with fixed shafts supported in the outer end of each piece. The shafts have a cantilevered end upon which thread rolling tools or the like are supported for rotation and are axially located by thrust bearings. Pivotal adjustment of the two base pieces permits different size workpieces to be accommodated. A synchronizing drive gear train is supported within the base and is adapted to be drivingly coupled to each of the tools so as to synchronize their rotation. The use of tapered bores for the tool holding shafts allows adjustment to compensate for wear in the components. In addition, one of the drive gears is supported for movement out of mesh with the other gears so as to adjust the synchronization between the tools.

Background of the invention This invention relates to a toolholder for thread rolling tools and more particularly to an improved toolholder wherein the tools are mounted outboard of the holder base.

Various types of thread rolling toolholders have been employed for forming threads or for use in other screw machine operations. One such prior art type tool holder is shown in United States Letters Patent 3,217,523, issued Nov. 16, 1965, entitled, Holder for Thread Rolling Tools, and in which I am a coinventor with James M. Burnett. This patent shows a holder for thread rolling tools that adapts itself to the use of different size tools and permits the forming of threads on different size articles. The holder shown in this patent provides for inboard mounting of the tools. That is, the tools are supported on shafts between the shaft ends and within the holder base. Although this type of construction has advantages in certain applications, it is not satisfactory for use in the formation of threads immediately adjacent a relatively large shoulder or on a relatively short workpiece. The present invention solves this problem by providing for the outboard mounting of the rolling tools, as well as other features which will be described.

It is, therefore, an object of this invention to provide an improved toolholder which overcomes the aforementioned disadvantages of known constructions.

It is another object of this invention to provide an outboard toolholder that does not require expensive adjustable bearings, yet provides for simple adjustment of the rotational axes of the rolling tools to accommodate wear and the like.

It is still a further object of this invention to provide an adjustable outboard toolholder that will support tools of different sizes and accommodate workpieces of different dimensions.

Summary of the invention A toolholder embodying this invention is particularly adapted to support thread rolling tools or the like. The toolholder is comprised of a holder base and a pair of spaced tool supporting shafts held against rotation by the holder base. One end of each of the tool supporting shafts is cantilevered outwardly from one face of the hold- 3,43 9,5 18 Patented Apr. 22, 1969 er base. Each cantilevered shaft end provides means for journaling a thread forming tool or the like thereupon. Synchronizing drive means are supported within the holder base and means are provided to establish a driving connection between each of the tools and the synchronizing drive means for synchronizing the rotation of the tools upon their respective supporting shaft ends.

Brief description of the drawings FIGURE 1 is a side elevational view of a toolholder embodying this invention.

FIGURE 2 is a side elevational view of the toolholder on the side opposite to that shown in FIGURE 1.

FIGURE 3 is an end elevational view of the toolholder, with a portion broken away.

FIGURE 4 is a perspective view of one piece of the toolholder base.

FIGURE 5 is a cross sectional view taken along the line 55 of FIGURE 1.

FIGURE 6 is a cross sectional view taken along the line 66 of FIGURE 5.

FIGURE 7 is a cross sectional view taken along the line 77 of FIGURE 5.

FIGURE 8 is a cross sectional view taken along the line 88 of FIGURE 5.

FIGURE 9 is a cross sectional view taken along the line 99 of FIGURE 5.

FIGURE 10 is a cross sectional view taken along the line 1010 of FIGURE 1.

FIGURE 11 is an enlarged cross sectional view taken along the line 1111 of FIGURE 5.

Detailed description of the preferred embodiment of the invention A toolholder base assembly embodying this invention is identified generally by the reference numeral 21, which base assembly is adapted to rotatably support a pair of thread rolling tools 22 and 23 adjacent one of its faces 24 and outboard thereof. It is to be understood that other types of rolling or forming tools may be supported by the holder base assembly 21, for example, serrating tools, knurling tools or other similar forming tools commonly used with screw machines.

The base assembly 21 is comprised of a fixed top plate 25 on the side opposite the face 24. The plate 25 has a pair of outwardly extending arms 26 and 27 that define a workpiece receiving recess 28. A dovetail portion 29 is formed integrally at the end of the plate 25 opposite the arms 26 and 27 for attachment of the holder base assembly 21 to a cooperating screw machine or the like.

The fixed top plate 25 is fixed to an adjacent fixed sup porting block, indicated generally by the reference numeral 31 and shown in perspective in FIGURE 4 of the drawings. The fixed block 31 is substantially the same in shape as the outer periphery of the adjacent portion top plate 25 and like the plate 29 is formed with a dovetail portion 32. Parallel bores 33 and 34 are formed in plate 25 and block 29. The bore 34 in the block 31 is tapped so as to receive a socket headed bolt 35 that is received in a counter bored hole in the face plate 25 and threaded into the tapped hole 34 to assist in holding the face plate 25 and fixed block 31 together. The block 31 is also formed with another tapped hole 36 into which a socket headed bolt 37 is threaded, which bolt also passes through an aligned counter bored opening on the face plate 25 to hold these parts together.

The portion of the block 31 adjacent the arm 26 is formed with a tapered bore 38 that receives a shaft 39 that extends at one end past the face 24 to support the tool 22 in a manner which will become more apparent as this description proceeds.

The block 31 is formed with a cutout 41 adjacent the dovetail portion 32 and next to the plate 25. An extending ear 42 of a pivoted block assembly, indicated generally by the reference numeral 43 extends into the cutout 41. The block 43 is formed with a bore 44 through which a smooth portion 45 of a socket headed shaft 46 extends. The socket headed shaft 46 is screw threaded, as at 47, and is received in a tapped hole 48 in the plate 25. The shaft 46, therefore, forms a journal about which the block assembly 43 may pivot.

The angular position of the pivoted block 43 with respect to the fixed block 32 is maintained in part by a pair of elongated socket headed bolts 51 that extend through tapered bores 52 (FIGURE 6) formed in the block 43. The bolts 51 are tapped into threaded holes 53 formed in the block 31 above the recess 41. The head of each bolt 51 bears against a respective shoulder 54 formed in the block 43 by a counter bored slot 55 so as to preclude pivotal movement of the block 43 with respect to the block 32 in a clockwise direction about the shaft 46 as viewed in FIGURE 6. Pivotal movement in the opposite direction is precluded by the engagement of a stud 56 (FIGURE 8) with a shoulder 57 formed on the block 29. The stud 56 is threaded into a tapped bore 58 formed in the block 43 (FIGURES 5 and 8) The block 43 is formed with a tapered bore 61 adjacent the plate arm 27 to supportingly receive a shaft 62 that extends outwardly from the toolholder face 24. This cantilevered shaft end supports the tool 23 in a manner which will become more apparent as this description proceeds.

The shafts 39 and 62 are held axially within the holder assembly 21 by means of socket headed bolts 65 and 66 that are threaded into tapped holes 67 and 68 formed in the outer ends of the shafts 39 and 62, respectively.

The head of the bolt 65 is received in a counterbore formed in a plate 25 and in addition to axially fixing the shaft 39 helps to restrain the block 32 with respect to the plate 25. The head of the bolt 66 is received in elongated counterbored slot 71 formed in the plate 25 and bears against a shoulder formed at the base of the slot 71 to affix the block 43 with respect to the plate 25 as well as axially restrain the shaft 62. The elongation of the slot 71 permits angular adjustment of the block 43 with respect to the plate 25, however, as will become more apparent as this description proceeds.

A fixed bottom plate 72 is secured to the outer face of the fixed block 32 by means of flat headed bolts 73 (FIG- URE 2). The plate 72 is formed with a grooved portion 74 (FIGURE 5) that receives an outwardly extending tongue 75 of a bottom plate 76 that is affixed to the pivoted block 43 by means of fiat headed bolts 77.

The outer end of the shaft 39 is formed with an enlarged diameter head portion 81 that is received in a recess 82 formed in the outer face of the thread cutting tool 22. A needle or roller type thrust bearing 83 is interposed be tween the head portion 81 and the shoulder formed at the base of the counterbore 82. A needle or roller type thrust bearing 85 is also interposed between the inner face of the thread cutting tool 22 and the outer face 24 of the cover portion 72. Thus, the threaded cutting tool 22 is axially held onto the shaft 39 between the thrust bearings 83 and 85 by the tension exerted on the shaft by bolt 65. The rolling tool 22 is, however, free to rotate upon a bushing 86 and upon the cantilevered shaft end. A like construction is provided for supporting the thread rolling tool 23 on the outer end of the shaft 62 and like reference numerals have been used to identify the thrust bearings and bushing.

The thread rolling tools 22 and 23 are interconnected by means of a synchronizing gear train, indicated generally by the reference numeral 87 and shown in most detail in FIGURE 7, so that their rotation will be synchronized when a workpiece is presented to them. The gear train 87 consists of a first gear 88 that is journaled upon the shaft 39 within a recess 89 formed in the face of the block 31 adjacent the plate 72. The gear 88 is formed with a pair of integral, forwardly extending keys 91 (FIGURE 1) that are received in somewhat larger keyways 92 formed in the inner face of the thread rolling tool 22. The keys 91 and keyways 92 thus form a driving connection between the gear 88 and the thread rolling tool 22 while allowing for some lost motion.

The gear 88 is in mesh with a larger diameter gear 93 that is journaled upon a stub shaft 94 that is threaded into the block 31. The gear 93 is positioned within a recessed portion 95 of the block 31 adjacent the plate 72 and is held in axial alignment by the plate 72.

The shaft 46 is provided with a reduced diameter end portion 96 that extends through a bore in block 31 and on which a gear 97 is journaled. The gear 97 is axially held onto the shaft portion 96 by means of a snap ring 98 and is in mesh with the gear 93 and with a gear 99 that is supported upon a threaded stub shaft 101 that is received in a tapped hole 102 formed in the pivoted block 43 (FIG. 10). The gear 99 is supported within a recess 103 formed in the outer face of a block 43 adjacent the plate 76 and axially fixed in place thereby. The gear 99 is engaged with a gear 105 that is journaled upon the shaft 62 and received within a cavity 106 formed in the block 43 adjacent the plate 76. The gear 105 also carries outwardly extending keys 107 that are received in enlarged keyways formed in the rolling tool 23 so that a driving connection with some lost motion is provided therebetween. The gear train 87 insures that the rolling tools 22 and 23 will rotate in unison but in opposite directions inasmuch as the rolling tools 22 and 23 engage opposite sides of the piece being threaded. The lost motion connections between the rolling tools and the gear train 87 insure proper synchronization when a rotating workpiece is fed into the cutting tools 22 and 23.

Each of the gears 88, 93, 97, 99 and 105 of the gear train 87 is thus supported in a respective recess in one of the blocks 31 or 43. Each of these recesses, with the exception of a recess 108 in which the gear 97 is contained, which recess is formed in the block 31, is of substantially the same depth as the thickness of the respective gear. The cover plates 72 and 76 thus serve to axially confine the respective gears within the respective cavities and axially fix the gears upon their respective supporting shafts. The cavity 108 has a depth that is at least equal to twice the thickness of the gear 97 for a reason which will become more apparent as this description proceeds.

As has been noted, the bores 38 and 61 that support the shafts 39 and 62, respectively, are tapered. Preferably these bores have a 1 taper with the smaller diameter portion being adjacent the face 24. Each of the shafts 39 and 62 is provided with a longitudinally extending slot 111 and 112, respectively. Headed studs 113 and 114 are tapped into the block 31 and engage the shaft 39 within slot 111 to preclude rotation of the shaft 39. In addition, the axial orientation of the shaft 39 with respect to the bore 38 can be altered by proper adjustment of the studs 113 and 114. A stud 115 bears against the inner end of the shaft 39 adjacent the larger diameter portion of the tapered bore 38 to facilitate the adjustment and assist in locating the shaft 39. Similar headed studs, identified by the same reference numerals, engage the shaft 62 so as to alter its axial location with respect to its supporting bore 61. Adjustment of the studs 113, 114 and 115 permits correction of the alignment of the axes of rotation of the cutting tools 22 and 23 to compensate for any wear that may occur in the parts. The axis of the studs 115 are displaced something less than from the axes of the studs 113 and 114 so as to facilitate this adjustment.

The disclosed toolholder assembly 21 is constructed in such a manner that it is extremely compact but is nevertheless extremely rigid so as to withstand the forming loads. The outboard mounting of the rolling tools 22 and 23 is accomplished without necessitating expensive thrust bearings inasmuch as the supporting shafts 39 and 62 are fixed against rotation within the holder base assembly 21. Thrust bearings need not be employed, therefore, to restrain the axial movement of these shafts.

If it is desired to change the tools supported upon the shafts 39 and 62, the socket headed bolts 65 and 66 are removed and the studs 113, 114 and 115 may be backed off slightly. The shafts 39 and 62 can then be slid axially out of the holder base assembly 21 along with the rolling tools 22 and 23. When new rolling tools are inserted upon the shafts 39 and 62 these shafts may again be inserted into the holder base assembly 21 and locked in position by insertion of the bolts 65 and 66 and appropriate adjustment of the studs 113, 114 and 115.

In some instances it may be desirable to alter the spacing between the shafts 39 and 62 and their respective rolling tools. This adjustment may readily be effected by loosening the socket headed bolt 66 and another socket headed bolt 121 that extends through an elongated counterbored slot 122 formed in the plate 25, which bolt is tapped into a threaded hole 123 formed in the block 43 (FIG. 6). The bolts 51 and stud 56 may then be adjusted in an appropriate manner so as to cause the block 43 to pivot about the shaft portion 46 with respect to the block 31. This adjustment is facilitated since the head of the stud 56 is accessible through an opening 124 formed in the side of the block 43 (FIG. 3). The elongation of the slots 71 and 122 in the plate 25 permit this adjustment, and when the desired adjustment is reached, the bolts 66 and 122 are retightened.

Upon changing the distance between the shafts 39 and 62 or under some other circumstances it may be necessary or desirable to adjust the angular relationship between the gears 88 and 105 to insure proper synchronization of the rolling tools. This adjustment may also be efiected externally by inserting a proper tool into the socket head of the shaft 46 and turning this shaft. Rotation of the shaft 46 will cause axial movement of this shaft and axial movement of the gear 97 within the cavity 106 due to the threaded connection 47, 48. The cavity 108 has sufficient depth to permit the gear 97 to be moved completely out of mesh with the gears 93 and 99. Thus, the gear 88 may be rotated independently of the gear 105 or vice-versa. When the desired angular relationship is reached, 'the shaft 46 is rotated in the opposite direction to bring the gear 97 back into mesh with the gears 93 and 99 and the desired synchronization will have been effected.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A toolholder for thread rolling tools or the like comprising a holder base, a pair of spaced tool supporting shafts held against rotation by said holder base, one end of each of said tool supporting shafts being cantilevered outwardly from one face of said holder base, each cantilevered shaft end providing means for journaling a thread forming tool or the like thereupon, synchronizing drive means supported within said holder base, and means for establishing a driving connection between each of the tools and said synchronizing drive means for synchronizing the rotation of the tools upon their respective supporting shaft ends.

2. A toolholder as set forth in claim 1 wherein each of the cantilevered shaft ends has an enlarged diameter end portion adapted to provide a reaction surface against which a thrust bearing may react between said surface and the supported tool, the adjacent face of said holder base providing a reaction surface against which another thrust bearing may react.

3. A toolholder as set forth in claim 1 further including means for angularly adjusting at least one of the supporting shafts to compensate for wear.

4. A toolholder as set forth in claim 1 wherein the tool supporting shafts are supported by the holder base for adjustment of the distance between said shafts.

5. A toolholder as set forth in claim 4 wherein the holder base comprises a first block and a second block pivotally supported with respect to said first block, said first block supporting one of the tool supporting shafts and said second block supporting the other tool supporting shaft whereby the adjustment of the distance between said shafts is effected by pivotal movement of said blocks with respect to each other.

6. A toolholder as set forth in claim 5 wherein each of said blocks is provided with recesses in the side adjacent the cantilevered ends of the tool supporting shafts, the synchronizing drive means comprising a gear train supported within said holder base with the respective gears being positioned in the respective cavities of said blocks.

7. A toolholder as set forth in claim 6 further including means for moving one of the gears out of engagement with other of the gears to adjust the synchronization between the tools.

8. A- toolholder as set forth in claim 7 wherein the means for moving the one gear out of engagement with other of the gears comprises a shaft supported by one of the blocks and axially movable with respect thereto, said one gear being r-otatably suported on said shaft and held against axial movement with respect thereto for movement of said one gear out of engagement with said other gears upon axial movement of said shaft.

9. A toolholder as set forth in claim 8 wherein the shaft supporting the one gear pivotally supports the second block with respect to the first block.

10. A toolholder as set forth in claim 9 wherein each of the blocks is formed with a tapered bore in which the respective tool supporting shaft is positioned, and means for holding each of said tool supporting shafts against rotation within said bore and for adjusting the angular position of each tool supporting shaft with respect to said bore.

References Cited UNITED STATES PATENTS 541,551 6/1895 Johnson 72-103 2,550,855 5/1951 Ostendorf 72--104 2,974,550 3/1961 Eigenbrode 72-101 CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner.

US. Cl. X.R. 72104

Images