US2994992A

US2994992A - Radius grinding machine and spindle

Info

Publication number: US2994992A
Authority: US
Publication date: 1961-08-08
Anticipated expiration: 1978-08-08

Description

Aug. 8, 1961 E. A. THOMPSON 2,994,992

RADIUS GRINDING MACHINE AND SPINDLE Original Filed Oct. 3, 1955 4 Sheets-Sheet 1 INVENTOR. FIG. 2 421. A. THOMPSON kMf ATT GENE V Aug. 8, 1961 E. A. THOMPSON 2,994,992

RADIUS GRINDING MACHINE AND SPINDLE Original Filed Oct. 3, 1955 4 Sheets-Sheet 2 3 V V g a; a l "0 N vm Q i m \9 9 k k asel z I 7 IN V EN TOR. .54 m A 77-IOMP50N ATTORNEY Aug. 8, 1961 E. A. THOMPSON 2,994,992

RADIUS GRINDING MACHINE AND SPINDLE Original Filed Oct. 3, 1955 4 Sheets-Sheet 4 mmvroa. 54EL 14. fi-IOMPJON A TTOENEY 2,994,992 Patented Aug. 8, 1961 8 Claims. (Cl. 51-97) This is a division of Serial No. 538,096, filed October 3, 1955, entitled Hydraulic Control Mechanism and now forfeited. The invention relates to grinding machines adapted for grinding a curved surface upon a work piece and especially to a machine for forming a spherical face upon the end of a part such as a tappet of the type used in association with an automotive engine camshaft.

It is an object of the present invention to provide an improved grinding machine having a slide construction which is adapted to produce surfaces of large radius with a high degree of accuracy and which is economical to construct.

A further object is to provide an improved spindle and collet construction especially adapted to operate in an automatic manner to load, chuck, grind and unload work pieces.

Another object is to provide a machine of this class which is readily adaptable to hydraulic motivation of its moving parts.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is illustrated.

FIG. 1 is an elevational view of a radius grinder incorporating the invention as viewed from the operator or front side of the machine.

FIG. 2 is a top elevational view of the machine shown in FIG. 1.

FIG. 3 is a sectional view on an enlarged scale, taken generally along the lines 33 in FIG. 2, showing the manner in which the table of the machine is mounted and guided for movement.

FIG. 4 is a sectional view along the lines 4-4 in FIG 3.

FIG. 5 is a sectional view of the spindle.

FIG. 6 is a View of the spindle as seen from the collet end thereof.

FIG. 7 is a sectional view taken along the lines 77 in FIG. 5.

FIG. 8 is an end View of the collet shown in the spindle illustrated in FIG. 5.

FIG. 9 is a sectional view taken along the lines 99 in FIG. 8.

FIG. 10 is a perspective view of one of the steel jaws of the collet.

FIG. 11 is an end view of a collet of modified construction.

FIG. 12 is a sectional view along the lines 1212 in FIG. 11.

This invention is admirably suited for use on an automatic radius grinding machine; and therefore, by way of description and not by Way of limitation, the invention is illustrated and described with reference to such a radius grinding machine.

Referring first to FIGS. 1 and 2 wherein the general organization of the machine is illustrated, the numeral 10 designates the base of the machine on which is mounted a grinding wheel 12 which is shielded by a housing 14. The driving mechanism for the grinding wheel 12 is not illustrated. A support 16 is mounted on base 10 for adjustment longitudinally of base 10, and a platform 18 is in turn mounted on support 16. At one end of platform 18, there is provided a pair of accurately machined,

upright ways

20 and 22 on which the table 24 is slidably supported for movement. At the opposite end of platform 18, there is mounted a gearbox 26 which in turn supports a cam box 28 at its front end and a motor 30 on its top face. Table 24 supports a spindle assembly 32; and adjacent the grinding wheel 12, there is arranged a feed mechanism generally designated 34 for loading work pieces in the collet of spindle 32. The collet within spindle 32 is rotated in a manner hereinafter described by a belt drive 36, FIG. 2, from an electric motor 38 mounted on table 24.

The gearbox 26 and cambox 28 are provided for the purpose of producing a co-ordinated program of motion cycles for each of the moving parts of the machine and these cam-produced movements are preferably trans rnittcd to the machine parts by means of closed liquid columns or pulsators indicated at 258, there being a separate cam and pulsator for each machine part which is to be actuated.

The conduits 258 each extend to the cylinder of one of the machine components that is hydraulically actuated. One of these conduits, namely, conduit 258b, connects with a cylinder 304 (FIG. 4) which is positioned below the front portion of table 24. As pointed out previously, table 24 is supported for sliding movement on the

machined ways

20 and 22. For controlling the particular path of movement of table 24, there is arranged on platform 18 a cam track 306 (FIGS. 2 and 3). In the arrangement shown, track 306 has an arcuate cam surface 308 (FIG. 3); and a follower 310 on the underside of table 24 is arranged to engage the cam surface 308. The followers 310 are urged into engagement with cam surface 308 by a pad 312 which is biased against the bevelled face of the straight Way 314 at one side of table 24. Pad 312 is biased by a piston 316 secured thereto and which operates in a cylinder 318 connected by a conduit 320 to a source of fluid, preferably oil under pressure. Conduit 320 preferably connects with an oil accumulator 321 (FIG. 2) on platform 18 which is designed to maintain a reservoir of oil under more or lms a uniform pressure. Cylinder 318 is mounted on a plate 322 having a stub shaft 324 thereon which is journalled for rotation in bearings 326 and 328 at a point on the radial center line of the cam face 308 on cam track 306 and preferably along the central axis of spindle 32. The extent of arcuate movement of table 24 is controlled by adjustable front and

rear stops

330 and 332, respectively.

Referring now to FIGS. 3 and 4, table 24 is provided at the central portion on the underside thereof with a depending stud 334. Piston

rods

336 and 338 are pivotally mounted on stud 334. Piston rod 336 connects with a piston 340 in cylinder 304 and rod 338 connects with a piston 342 in cylinder 344. Cylinder 304 is pivotally supported as at 346 adjacent the front side of platform 18, and cylinder 344 is pivotally supported on platform 18 as at 348 adjacent the rear side of platform 18. The inlet port 350 of cylinder 344 is connected by a con duit 352 with accumulator 321 (FIG. 2). The pressure of the oil in accumulator 321 is maintained at a value such that the accumulator pressure in cylinder 344 is sufficient to return the table 24 to a position against the front stop 330. The table is adapted to be moved by means of the cam in direct motion which is transmitted to the cylinder 304 by the pulsator 2581) which overcomes the bias of the accumulator 321 acting in cylinder 344 during the rising part of the cams rotation. Return motion takes place on the falling part of the cam rotation and is produced by the bias pressure acting in cylinder 344, but the motion is under the full control of the receding cam which may have any suitable contour designed to produce the desired forward and return motions of the table 24.

In FIGS. 5 through 7, the details of spindle assembly 32 are shown. The spindle assembly includes a housing 366 secured to table 24; and within housing 366, there is arranged a sleeve 368. Sleeve 368 is fastened and sealed to the housing 366 and has axially extending cuffs spaced radially inwardly to define front and rear annular chambers 370 and 372, respectively, in which are arranged pistons 374 and 376. An annular seal 378 is associated with piston 374, and an annular seal 380 is associated with piston 376. Within housing 366 and extending through sleeve 368, there is arranged the collet driving spindle 382 which has bearings 384 and 386 press fitted thereon. Bearing 384 is slidably arranged within the counterbore 388 of housing 366, and bearing 386 is slidably arranged within the counterbore 390 of the housing. The chamber in which piston 374 operates has an inlet port 392 and the chamber with which piston 376 is associated has an inlet port 384. Port 392 has conduit 258 from the cam box connected thereto, and port 3594 connects with a conduit 396 which is in turn connected with the accumulator 321. With this arrangement, when the follower associated with the cam that controls the advancement and retraction of the spindle rides up on the high side of the cam, oil under pressure is fed through port 392 to advance piston 374 and in turn to shift the collet spindle 382 forwardly or to the left as viewed in FIG. 5 to a fixed position wherein the outer race of the rear bearing 386 abuts against the shoulder 398 of counterbore 390. As the cam follower rides around the low side of the cam, the oil under pressure from the accumulator 321 is introduced into port 394; and piston 376 shifts the collet spindle 382 rearwardly to the position shown in FIG. 5 where the outer race of bearing 384 abuts against the shoulder 400 of counterbore 388. At its front end, spindle 382 supports a tapered nose piece 402 in which the correspondingly tapered collet 404 is arranged. At its rear end, spindle 382 has a threaded connection with a pulley 406 which, as mentioned previously, has a belt drive 36 with the motor 38 on table 24.

Collet 404 has a rubber body portion 408 in which are embedded radially extending steel jaws 410. Around the outer periphery of the collet, the body 408 is provided with pockets 412 between adjacent steel jaws 410; and nose piece 402 is provided with one or more collet drivers 414 which engage in pockets 412 to rotate the collet in response of rotation of spindle 382. In the arrangement shown, the work piece designated 416 is in the nature of a cylindrical body member; and the collet 404 is arranged to clamp the work piece securely when the collet is shifted forwardly or to the left in FIG. 5 so as to be contracted by the tapered nose piece 402.

The means for clamping and releasing' the collet are in the form of a drawbar 418 having at the forwardend thereof an annularr adially outwardly extending'flange 420 which is spaced from the body of the drawbar by a reduced collar portion 422. Adjacent the rear end of the bore in collet 404, there is fashioned an annular groove 424 and a lip 426, FIG. 9, which are arranged to engage respectively with'the flange 420 and collar 422 of drawbar 418. Within the rear end of drawbar 413, there is rotatably supported, as by a bearing 428, a sleeve 430. Sleeve 430 extends through a bushing 432 rotatably supported as by a bearing 434 in pulley 406. Bushing 432 has a threaded outer end portion 436 on which a hex nut member 438 is threaded. A cylindrical body member 440 is rigidly fixed on and sealed to nut member 438. At its rear end, sleeve 430 is fashioned with a reduced portion on which an annular piston 442 is fixed. Piston 442 is arranged to slide within a chamber 444 of the cylindrical body member 440. The portion of chamber 444 to the rear of piston 442 has a port 446 connected with the conduit 258d from the cam box, and the portion of chamber 444 ahead of piston 442 has a 41. port 448 to which is connected a conduit 450 which in turn connects with accumulator 321. When oil under pressure from the cam box 28 is introduced into port 446 through line 258d, piston 442 moves forwardly and in turn shifts sleeve 430 in a forward direction. Sleeve 430 acts through bearing 428 to advance the drawbar 418 and thus collapse the collet 404 around the work piece 416 by reason of its engagement with the tapered nose piece 402.. When the pressure at port 446 is relieved by reason of the cam follower associated therewith riding onto the low side of cam, the pressure of the oil from accumulator 321 at port'448 retracts piston 442 and thus releases collet 404. The cam that controls the actuation of drawbar 418 is designed so that the collet 404 clamps the work piece before the cam follower reaches the highest point on the rise of the cam. Thus, a positive gripping action is insured.

Within sleeve 430, there is slidably arranged anejector bar 452 which is journalled at its front end in a bearing 454 slidably supported within the cup-shaped rear end 456 of an ejecting plunger 458. A spring 460 within plunger 458 urges a disc 462 against bearing 454. At the rear end of ejector bar 452, there is fixed a piston 464 which is slidably arranged in a chamber 466 within the rear end of cylindrical body member 440. The portion of chamber 466 to the rear of piston 464 has a port 468 to which line 258@ from the cam box is connected. The portion of chamber 466 on the front side of piston 464 has a port 470 to which is connected a conduit 472. Conduit 472 extends to the accumulator 321. When oil under pressure from the cam box 28 is introduced at port 468 through the line 258e, the piston 464 and ejector rod 452 are shifted forwardly or to the left as viewed in FIG. 5; and rod 452 in turn acts through disc 462 and spring 460 to eject the work piece 416 from the collet which has previously been released by drawbar 418. \Vhen the cam follower in cam box 28 controlling the operation of ejector rod '452 rides over the highest part of cam 232, the pressure at port 468 is relieved and the accumulator pressure at port 470 moves the piston 464 to the right against the stop formed by the fitting 474 and thus retracts the ejector plunger 458 to the position shown in FIG. 5.

The collet shown in FIG. 5 is illustrated in greater de-' tail in FIGS. 8, 9 and 10; and a modified form of the collet is shown in FIGS. 11 and 12. In the arrangement shown in FIG. 12, the collet is adapted to be used in an arrangement wherein it is contracted by being retracted into a collapsing member rather than being advanced into a tapered member such as the nose piece 402 illustrated in FIG. 5. Thus, the collet illustrated in FIGS. 11 and 12 has its outer surface 475 tapering inwardly in a direction from the front end thereof rather than outwardly as in the case with the collet illustrated in FIGS. 8 and 9. With the collet of PTGS. 11 and 12 the

fluid conductors

450 and 258d leading to drawbar cylinder 444 will be transposed so that the drawbar 418 is shifted to the right in FIG. 5 to close the collet and to the left to open it. In other respects, these two forms of collets are substantially the same; and the collet shown in FIGS. 11 and 12 likewise includes an annular groove 476 and a shoulder portion 478 adjacent its rear end which is adapted for interengagement with a drawbar of the type shown at 418 in FIG'FS.

Referring again to FIG. 5, it will be observed that adjacent the collet 404, the drawbar 418 is provided with radial openings 480; and the nose piece is also provided With radial openings 482. These openings are desirable to permit dirt or other accumulations around the collet to be discharged from the spindle upon rotation. An oil seal 484 is provided between the hub of pulley 406 and the rear end of the bore of housing 366, and a similar oil seal 486 is provided between the front end ofthe bore of housing .366 and the collet supporting spindle 382. Adjacent the seal 486, there is provided a felt wiper 488.

Oil seals 490 and 492 are also provided adjacent the front and rear ends of the collet supporting spindle 382. At least some of these oil seals are arranged to permit a slight leakage of oil from within the spindle assembly. Dirt is thus prevented from accumulating within the spindle.

After the machine is once set in operation, it continues to operate automatically, one complete cycle of operation being performed during each revolution of the cam shaft 218. With the table in the load position, a Work piece is fed into collet 404. The collet clamps the work piece as the table moves rapidly towards the feed position. The work piece is then traversed across the face of the grinding wheel in the desired arcuate path and at the desired feed rate.

When the table reaches the end of its work stroke, the table is then returned to the starting position by means of the pressure in accumulator 321, but the rate at which the table is returned is controlled by the shape of the cam. The collet is then expanded and the work piece ejected.

It will thus be seen that I have provided an improved table support and spindle construction especially adapted for automatic mechanico-hydraulic actuation and which may be utilized especially for producing large radius curved surfaces upon the ends of such work pieces as valves, valve tappets and the like.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adapted, all coming Within the scope of the claims which follow.

I claim:

1. A spindle assembly for rotatably supporting a work piece comprising a housing, a spindle rotatably supported in said housing, a nose piece having a comically shaped inner face, said nose piece being mounted at one end of said spindle, a rubber collet in said nose piece having an outer surface corresponding in shape with the conical inner face of said nose piece, said collet having an axial bore for receiving a work piece and a plurality of radially and longitudinal extending vanelike jaws inset in the rubber, said collet, when moved axially in one direction in said nose piece, being contracted by the nose piece into engagement with the work piece in said collet and when shifted axially in the opposite direction, moving away from the conical surface of said nose piece to expand out of engagement with the work piece, said bore at the inner end of said collet having an annular groove, a drawbar having a radially outwardly extending flange at one end thereof engaged in said groove and means for shifting said drawbar axially to contract and expand the collet.

2. The combination called for in claim 1 wherein said drawbar is supported to rotate with said spindle, said means for shifting said drawbar including a shaft extending axially from the opposite end of said drawbar, a bearing connecting said shaft and said drawbar for relative rotation in axially fixed relation.

3. The combination called for in claim 2 including a plunger extending axially in said drawbar, said shaft being hollow, a rod in said hollow shaft aligned axially with said plunger, means acting between said shaft and 6 said plunger and yieldably biasing said plunger in a direction outwardly through the bore of said collet and means for shifting said shaft axially whereby to eject the work piece from the collet when the collet has been expanded.

4. In a machine tool, a support, an arcuate cam track on said support, -a table having a plurality of cam followers and a rectilinear guide, means for reciprocating said table along said cam track and means for maintaining said cam followers in engagement with said cam track comprising a pad slidably engaging said rectilinear guide, a cylinder pivotally supported between the center of curvature of said arcuate track and said cam followers, a piston in said cylinder engaging said pad so as to urge the followers into engagement with said track and means for applying fluid under pressure to said cylinder.

5. The combination called for in claim 4 wherein said rectilinear guide is perpendicular to the resultant of the reaction force between the cam followers and the cam track.

6. In a machine tool, support means, table means shiftably mounted on said support means, a longitudinal cam member carried by one of said means, a cam follower member carried by the other means, an actuator for shifting the table means back and forth along a path determined by the cam and follower members, and means for preloading the cam and follower members comprising a fluid pressure loaded expansible chamber having one wall connected to one of the means, a longtiudinal guide generally paralleling the cam member and connected to the other of the means, and a guide follower, said guide and follower co-operating with another wall of the chamher for impressing a preloading force upon the cam and follower members.

7. A machine tool construction according to claim 6 wherein the longitudinal cam member is curved and the longitudinal guide is straight.

8. In a machine tool, support means, table means shiftably mounted on said support means, a longitudinal cam member carried by one of said means, a cam follower member carried by the other means, an actuator for shifting the table means back and forth along a path determined by the cam and follower members, and means for preloading the cam and follower members compnising a resiliently expansible member, a longitudinal guide element generally paralleling the cam member, a guide follower element, one element being mounted on the table means and the other on the support means, an element being connected with the expansible member for impressing a preloadi-ng force upon the cam and follower members.

References Cited in the file of this patent UNITED STATES PATENTS 1,255,962 Warner et a1. Feb. 12, 1918 2,058,731 Sherrilf Oct. 27, 1936 2,403,136 Stoner July 2, 1946 2,648,175 Fraser Aug. 11, 1953 2,775,073 Ingersoll et a1 Dec. 25, 1956 FOREIGN PATENTS 186,947 Austria Sept. 25, 1956