US3902281A

US3902281A - Workpiece grinder with lead generating capability

Info

Publication number: US3902281A
Application number: US455543A
Authority: US
Inventors: Douglas M Mccord; Victor J Laing; Darrell D Diem
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1974-03-28
Filing date: 1974-03-28
Publication date: 1975-09-02
Anticipated expiration: 1992-09-02

Abstract

A machine having a drive motor which rotates a tapered workpiece having peripheral cutting spirals through constant velocity universal joints and which simultaneously moves the workpiece longitudinally to generate a lead which corresponds to the lead of the cutting spirals. The machine has an upper table which can be horizontally tilted to compensate for the taper of the workpiece so that a rotating grinder wheel, fixed in a predetermined vertical position above the workpiece, frictionally engages and grinds each cutting spiral as the workpiece is driven. A lead start selector permits workpiece to be turned relative to the grinder wheel before a grinding operation so that the start of any cutting spiral is engaged by the grinding wheel.

Description

llnited States Patent [191 McCord et a1.

[ 1 Sept. 2, 11975 WORKPIECE GRINDER WITH LEAD GENERATING (IAPABILITY [75] Inventors: Douglas M. McCord, Grand Blanc;

Victor .1. Laing; Darrell D. Diem, both of Flint, all of Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: Mar. 28, 1974 21 Appl. No.: 455,543

Primary ExaminerAl Lawrence Smith Assistanl Examiner-Nicholas P. Godici Attorney, Agent, or FirmCh;ar1es R. White 5 7 ABSTRACT A machine having a drive motor which rotates a ta pered workpiece having peripheral cutting spirals through constant velocity universal joints and which simultaneously moves the workpiece longitudinally to generate a lead which corresponds to the lead of the cutting spirals. The machine has an upper table which can be horizontally tilted to compensate for the taper of the workpiece so that a rotating grinder wheel, fixed in a predetermined vertical position above the workpiece, frictionally engages and grinds each cutting spiral as the workpiece is. driven. A lead start selector permits workpiece to be turned relative to the grinder wheel before a grinding operation so that the start of any cutting spiral is engaged by the grinding wheel.

3 Claims, 4 Drawing Figures PATENTED SEP 21975 WORKPIECE GRINDER WITH LEAD GENERATING CAPABILITY This invention relates to workpiece grinders and more particularly to a machine for grinding the cutting spirals of tapered workpieces in which the workpiece can be adjusted to predetermined horizontal positions, rotated and longitudinally traversed to generate the lead of the cutting spirals to permit a rotating grinding wheel fixed in vertical position to sharpen the cutting spirals.

The preferred embodiment of this machine has a fixed base which supports a longitudinally movable lower table. An upper table, carried by the lower table, can be tilted relative to the lower table to place a tapered cylindrical workpiece supported on the upper table in a position to effectively eliminate the workpiece taper to facilitate grinding of the workpiece. A rotatable grinding wheel fixed at a vertical station frictionally engages a cutting spiral of the workpiece as the workpiece is rotated and moved longitudinally by speed controlled power transmission means that generates a lead which corresponds to the lead of the cutting spiral. The workpiece is held on the upper table by headstock and tailstock means. The headstock carries adjustable lead start selector means which permits the rotational adjustment of the workpiece so that cutting spirals intermediate of a first spiral and having spaced starts can be effectively matched with the grinding wheel for subsequent grinding operations.

The machine has a gear box fixed to the stationary base which supports a hydraulic motor. This motor drives a gear train which is drivingly connected to a rotatable shaft in the head stock through constant velocity universal joint means allowing the rotatable shaft and the workpiece to be driven at a constant velocity and further allowing the upper table to be tilted relative to the lower table. The rotatable shaft in the head stock is connected to the lead start selector by indexing means which permits the adjustment of the lead start selector relative to the rotatable shaft so that the start of different spirals of the workpiece can be matched with the grinding wheel. The gear train further drives a lead screw that extends through a ball nut that is connected to the lower table to provide for the traversing of the lower table, the upper table, the headstock, the tailstock. and the workpiece carried thereby. With this construction the workpiece will be moved longitudinally as it is turned so that the lead of the spiral is generated by the machine. The gearing in the gear box can be readily changed to change the lead generated and provide for the grinding of workpieces having different leads. I

These and other features, objects and advantages of the invention will be more apparent from the following detailed description and drawing in which:

FIG. I is a side view of a preferred embodiment of the invention;

FIG. 2 is a view taken generally along lines 2--2 of FIG. 1 with some parts being shown in cross section;

FIG. 3 is a view taken generally along lines 33 of FIG. 2 and FIG. 4 is a fragmentary view taken generally along lines 4-4 of FIG. 2.

Turning now to the drawings there is shown in FIG. I a workpiece grinding machine having a stationary base on which there is mounted a longitudinally movable lower table 12. This movement is provided by conventional T-slots in the top surface of the base 10 which receive cooperating slides projecting from the lower table 12. The lower table 12 has an upstanding support 16 fixed near one end thereof which receives a pivot pin 18 secured to an upper table 20. The lower table also has an adjustment screw 22 threaded therein adjacent to the other end formed with a rounded tip 23 which bears against the lower-surface of the upper table. A handle 24 fixed to the adjustment screw is used to manually turn the adjustment screw to pivot the upper table a limited extent about pivot pin 18 and thereby tilt the upper table with respect to the lower table. After being tilted a sufficient amount, a Jo block 26 is positioned between a support pad 28, fixed to the lower table 12, and a sine bar 30 fixed to the upper table 20. After the .10 block is installed in position, the adjustment screw 22 is retracted into the lower table so that the sine bar rests on the Jo block to provide a precise and predetermined inclination of the upper table with respect to the lower table to position the tapered workpiece 32, supported by the upper table 20, in a horizontal position to compensate for the taper angle of the workpiece.

The machine has a headstock 34 which is adjustably mounted in longitudinally extending T slots, not shown, in the top of upper table 20 and which is secured in adjusted position by locking screw means 36. A rotatable drive shaft 38, journaled in the headstock, has a projecting end on which a thread lead start selector 42 is rotatably mounted. The rotatable drive shaft 38 further has a disc-like front plate 44 fixed thereto adjacent to the thread lead start selector 42 which carries an indexing plunger 46.

The indexing plunger 46 has a movable projecting finger portion 47 which extends through the front plate and is removably engageable with any one of a circular series of equally spaced holes 48 drilled into the adjacent end surface of the lead start selector. When so engaged the lead start selector is drivingly secured to the rotatable front plate 44. By axially withdrawing the finger portion from one of the openings 48, the lead start selecter can be rotated relative to the front plate 44 to predetermined adjusted positions and again connected with the front plate 44 by extending finger 45 into an aligned opening 48. As will be later described this procedure is used to rotate the workpiece 32 so that the spaced lead starts of different cutting spirals of the workpiece can be engaged by a grinding tool.

The front face of the lead start selector 42 has a pair of lugs 47 secured thereto which receive threaded adjustment screws 49. These screws adjustably secure a driver 50 to the lead start selector 42 so that the lead start selector can be rotated relative to the front plate the driver. The workpiece in the drawing is a spiraled broach which is mounted between aligned centers 52 and 54 extending longitudinally from the lead start selector 34 and from a tailstock 56 adjustably mounted in the T slots in the top of the table 20. Screw locking means 58 is employed to secure the tailstock in ad justed position. The headstock 34 and tailstock 56 are advanced or retracted with respect to each other to accommodate workpieces of varying lengths. The tail stock has a hand wheel 60 connected to the center 54 by a shaft threaded through the tailstock which is turned clockwise or counterclockwise to accordingly advance or retract the center 54 to facilitate loading and unloading of broaches into the machine.

As shown, the broach 32 has a stem 62 which extends through a central yoke 64 of the driver and is locked thereto by a screw 66 which is threaded through the yoke into engagement with the stem 62. The broach can have one or more leads, for example broach 32 can have separate cutting spirals 68, 70 and 72. These spirals have starts spaced 120 apart spiraling around the periphery of the broach from the larger end to the smaller end. The three separate cutting spirals are sharpened by a grinding assembly 74 which has a housing 76 pivotally mounted on a stationary column 78 that may be fixed to the base 10. As shown, the grinding assembly 74 has a powered rotatable grinding wheel 80 that is positioned by turning the housing to a predetermined fixed station in which the grinding wheel is in grinding contact with the front face of a selected one of the three cutting spirals.

To rotate and traverse the spiral broach, a hydraulically operated power transmission is employed. As shown in FIG. 1, there is a hydraulic motor 84, fixed to a gear box 86, which drives a spur gear 88. Spur gear 88 meshes with a second spur gear 90 which is drivingly connected to a constant velocity universal joint 92 disposed adjacent to one side of the gear box. Universal joint 92 is drivingly connected to a shaft 94 which is in turn drivingly connected to a second constant velocity universal joint 96 that is supported by a steady rest 98 secured to the gear box. The second universal joint is drivingly connected to a rotatably splined shaft 100 that extends longitudinally through the headstock and into a longitudinally extending tubular cover 102 which is supported at one end by a plate 103 fastened to the headstock and at the other end by a support 104 fixed to table 20. The headstock 34 has a spur gear 106 which is slidably mounted on and is rotatably driven by the splined shaft 100. This spur gear meshes with a second spur gear 108 which drives shaft 38 that extends through the headstock and which is drivingly connected with front plate 44. Thus, when the index plunger 46 is engaged with one of the holes 48 in the lead start selector and the connected spiral broach 32 will be rotatably driven at a constant velocity by the motor 84.

The hydraulic motor 84 also supplies the power to longitudinally move the spiral broach 32 as it is being rotated. As shown. the spur gear 90 is connected to a larger spur gear 107 which drives a gear train comprising meshing gears 109, 110 and 112. Spur gear 112 rotatably drives a lead screw 114 which extends through a passage in the lower table 10 and is rotatably journaled in a lead screw support 116 located at the far end of the base. A ball nut 118, mounted on the lead screw. is connected to the lower table by a bracket 120 so that rotation of the lead screw moves the lower table and the connected upper table longitudinally with respect to base 10. Since the headstock and tailstock are fixed to the upper table these components will be moved along with the upper table and the broach is thus moved longitudinally as it is being rotated.

Suitable controls, not shown, for the hydraulic motor 84 are employed to control the speed and direction of rotation of motor 84.

The constant velocity universal joints permit the tilt adjustment of the upper table relative to the base so that the tapered workpiece can be positioned at a selected angle to compensate for the angle of taper. .Also, these universal joints provide for the rotation drive of the workpiece at a constant angular velocity. This important feature permits the turning speed of the workpiece to be corrolated with the traversing speed of the workpiece. For example if the spirals 68, 70 and 72 have a one inch lead, the workpiece must be longitudinally traversed one inch for each revolution. This is accomplished by the appropriate selecton of gearing for the gear train. If the rotation of shaft 114 produces a 1 inch longitudinal movement of the tables the gearing should be selected so that shafts 100 and 114 are driven at the same speed. For other leads appropriate gearing may be readily substituted for the gearing in gear box 86.

To prepare the machine for a grinding operation the headstock and tailstock are set a predetermined distance from each other to accommodate the length of a workpiece such as the tapered spiral broach 32. The broach 32 is placed in the machine with the stem 62 inserted through the driver yoke 64 and in engagement with the center 52. Wheel 60 is turned to advance the center 54 of the tailstock into engagement with the other end of the broach 32. Driver screw 66 is advanced in the yoke to rigidly secure the broach to the driver. After the broach is loaded, the upper table is tilted and a selected Jo block 26 is installed to fix the angle of inclination of the upper table 20 to equal the taper of the broach. This adjustment makes the top line or upper surface of the broach parallel to the machine base 10. After the upper table is inclined, the upper and lower tables are longitudinally moved to locate the portion of the broach requirihg sharpening adjacent to the grinding wheel assembly 74. During this movement the housing 76 and connected grinding wheel 80 have been turned to an out-of-the-way position. For example, the broach is moved longitudinally to the right until the grinding wheel 80 is adjacent to the larger diameter end of the broach. The lead start selector is turned until the start of a selected spiral 68 is properly aligned with the grinding wheel 80 when it has been turned into a working position such as shown in FIG. 1. Screws 49 can be used as a fine adjustment for turning the workpiece 32. After this setup, the motor 84 is activated to turn the broach 32 counterclockwise as it is being moved leftwardly. With the grinder wheel 80 rotatably driven and with the broach turning as it is being longitudinally traversed, the grinder wheel will grind the spiral 68 to sharpen this spiral from one end to the other. In the event that only a portion of the spline need be sharpened the machine setup can be such that only the portion of the broach that needs to be ground is worked on by the grinding wheel. In a similar manner the other spiral splines 70 and 72 are ground. After the broach has been ground, the grinder assembly 74 is turned to its out-of-the-way position and the broach is removed from the machine.

While a preferred construction has been shown and described for purposes of illustrating this invention, the scope of the invention is set forth by the following claims.

We claim:

1. A grinder for a workpiece comprising a stationary base, first table means mounted for longitudinal movement on said base, second table means, pivot means mounting said second table means on said first table means for limited tilting movement about a horizontal axis, tailstock means mounted on said second table means, lead start selector means rotatably mounted on said second table spaced from said tailstock means, said workpiece being elongated and tapered and having cutting spiral means disposed around the periphery thereof, said workpiece having an end portion secured to said lead start selector means and another end portion supported by said tailstock means, rotatable spiral grinder means positioned at a predetermined station adjacent to said workpiece, means to tilt said second table means with respect to said first table means at an angle equal to the taper angle of said workpiece, motor means for simultaneously rotating and traversing said workpiece relative to said grinder means, first power transmission means operatively connecting said motor means to said lead start selector means to drive said lead start selector means and said workpiece at a constant angular velocity, second power transmission means operatively connecting said motor means to said second table means for longitudinally moving said second table means and said workpiece at a predetermined speed to thereby generate a lead equal to the lead of said cutting spiral means so that said grinder means can effectively grind said cutting spiral means.

2. A grinder for a workpiece comprising a stationary base, first table means mounted for longitudinal sliding movement on said base, second table means, horizontal pivot means mounting said second table means on said first table means for limited tilting movement with respect to pivot means, spaced headstock and tailstock means mounted on said second table means, lead start selector means, said workpiece being elongated and tapered and having cutting spiral means disposed around the periphery thereof, said workpiece having an end portion secured to said lead start selector means and another end portion supported by said tailstock means, rotatable spiral grinder means positioned at a predetermined station adjacent to said workpiece, gauge means to tilt and fix said second table means with respect to said first table means at an angle equal to the taper angle of said workpiece, motor means fixed with respect to said base for simultaneously rotating and traversing said workpiece relative to said grinder means, first power transmission means operatively connecting said motor means to said lead start selector means, said first power transmission means having first and second constant velocity universal joints operatively connecting said lead start selector means to said motor means to permit said second table means to be tilted relative to said first table means and to drive said lead start selector means and said workpiece at a constant angular velocity, indexing means for adjustably securing said lead start selector means to said first power transmis sion means, second power transmission means operatively connecting said motor means to said second table means for longitudinally moving said second table means and said workpiece at a predetermined speed to thereby generate a lead equal to the lead of said cutting spiral means so that said grinder means can effectively grind said cutting spiral means.

3. A lead generating grinder for a tapered workpiece having a plurality of cutting spirals with spaced lead starts comprising a stationary base, first table means, slide means mounting said first table means for longitudinal movement along said base, second table means, pivot means pivotally mounting said second table means on said first table means, headstock means mounted on said second table for continuous rotation about a longitudinal axis, tailstock means, means adjustably mounting said tailstock means on said second table at a spaced and predetermined distance from said headstock means, lead start selector means supported by said headstock means for rotation therewith, index means for adjustably securing said lead start selector means at different selected positions with respect to said headstock means, said workpiece having an axis coinciding with said longitudinal axis and having one end thereof rotatably supported in said tailstock means and the opposite end thereof fastened to said rotatable lead start selector means, rotatable grinder means positioned at a predetermined station adjacent to said workpiece, means to adjust the angle of said second table with respect to said base so that the upper surface of said tapered workpiece is parallel to said base, a motor, power transmission means; operatively connecting said motor to said headstock means and to said first table means to permit said motor to simultaneously rotate said headstock means and longitudinally move said tables to thereby simultaneously rotate and longitudinally move said workpiece to permit said grinder means to grind the spirals of said workpiece beginning with the lead starts thereof, and indexing means for adjustably securing said lead start selector means at different rotary positions with respect to said headstock means so that said grinder means can be positioned to grind the spaced lead-starts of each of the spirals of said UNITED STATES PATENT AND TRADEMARK OFFICE QER'TTFICATE OF CORRECTION PATENT NO. 3, 902,281

DATE September 2, 1975 INV ENTOR( I Douglas M. McCord et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 53, "be rotated relative to the front plate" should be can rotate the workpiece 32 connected to line 43, "selecter" should be selector Column 4, line 7, "selecton" should be selection Signed and sealed this thirteenth Day Of April 1976 [SEAL] A ttes I:

RUTH C. MASON Arresting Officer C. MARSHALL DANN (mnnu'ssimu'r uj'lau'r'zrs and Trademarks

Claims

2. A grinder for a workpiece comprising a stationary base, first table means mounted for longitudinal sliding movement on said base, second table means, horizontal pivot means mounting said second table means on said first table means for limited tilting movement with respect to pivot means, spaced headstock and tailstock means mounted on said second table means, lead start selector means, said workpiece being elongated and tapered and having cutting spiral means disposed around the periphery thereof, said workpiece having an end portion secured to said lead start selector means and another end portion supported by said tailstock means, rotatable spiral grinder means positioned at a predetermined station adjacent to said workpiece, gauge means to tilt and fix said second table means with respect to said first table means at an angle equal to the taper angle of said workpiece, motor means fixed with respect to said base for simultaneously rotating and traversing said workpiece relative to said grinder means, first power transmission means operatively connecting said motor means to said lead start selector means, said first power transmission means having first and second constant velocity universal joints operatively connecting said lead start selector means to said motor means to permit said second table means to be tilted relative to said first table means and to drive said lead start selector means and said workpiece at a constant angular velocity, indexing means for adjustably securing said lead start selector means to said first power transmission means, second power transmission means operatively connecting said motor means to said second table means for longitudinally moving said second table means and said workpiece at a predetermined speed to thereby generate a lead equal to the lead of said cutting spiral means so that said grinder means can effectively grind said cutting spiral means.

3. A lead generating grinder for a tapered workpiece having a plurality of cutting spirals with spaced lead starts comprising a stationary base, first table means, slide means mounting said first table means for longitudinal movement along said base, second table means, pivot means pivotally mounting said second table means on said first table means, headstock means mounted on said second table for continuous rotation about a longitudinal axis, tailstock means, means adjustably mounting said tailstock means on said second table at a spaced and predetermined distance from said headstock means, lead start selector means supported by said headstock means for rotation therewith, index means for adjustably securing said lead start selector means at different selected positions with respect to said headstock means, said workpiece having an axis coinciding with said longitudinal axis and having one end thereof rotatably supported in said tailstock means and the opposite end thereof fastened to said rotatable lead start selector means, rotatable grinder means positioned at a predetermined station adjacent to said workpiece, means to adjust the angle of said second table with respect to said base so that the upper surface of said tapered workpiece is parallel to said base, a motor, power transmission means operatively connecting said motor to said headstock means and to said first table means to permit said motor to simultaneously rotate said headstock means and longitudinally move said tables to thereby simultaneously rotate and longitudinally move said workpiece to permit said grinder means to grind the spirals of said workpiece beginning with the lead starts thereof, and indexing means foR adjustably securing said lead start selector means at different rotary positions with respect to said headstock means so that said grinder means can be positioned to grind the spaced lead starts of each of the spirals of said workpiece.