US3594955A - Universal shoe guide for a centerless grinding machine - Google Patents

Abstract

The invention contemplates a universal fixture adjustably supporting a set of selectively locked spring-loaded pins which may be released to conform to the workpiece diameter to be supported, and which may be locked to retain the correct worksupport arc for the particular workpiece. Fixtures for internal grinding and for external grinding are shown.

Description

United States Patent lnventors Appl. No.

Filed Patented Assignee Bertrand Collin New Britain;

Victor J. Baccaro, Southington, both 01, Conn.

Sept. 9, 1968 July 27, 1971 Textron Inc.

Providence, R.I.

UNIVERSAL SHOE GUIDE FOR A CENTERLESS GRINDING MACHINE 14 Claims, 5 Drawing Figs.

U.S. Cl 51/103, 51/238 Int. Cl 1324b 5/18 Field oISearch 51/236,

238.1,103, 103 C, 103 WH [56] References Cited UNITED STATES PATENTS 2,048,467 7/1936 Roehrn 51/103 2,478,607 8/1949 Theler et al 51/103 Primary ExaminerTravis S. McGehee Attorney-Hopgood and Calimafde ABSTRACT: The invention contemplates a universal fixture adjustably supporting a set of selectively locked spring-loaded pins which may be released to conform to the workpiece diameter to be supported, and which may be locked to retain the correct work-support arc for the particular workpiece. Fixtures for internal grinding and for external grinding are shown.

UNIVERSAL SHOE GUIDE FOR A CENTERLESS GRINDING MACHINE In the field of centerless grinding, the workpiece must be supported by a shoe that generally is provided with a workpiece-supporting contoured surface substantially conforming to the outside surface circumference of the workpiece after grinding. Such shoes require machining of a set of roughing and finishing shoes for each different workpiece. This is a cumbersome and uneconomical approach for centerless grinding installations requiring frequent workpiece changes.

It is therefore an object of this invention to provide a universal fixture for centerless grinding of a workpiece wherein machine adjustments and setup time as greatly simplified and quick workpiece changes are made possible.

It is a further object to provide a universal fixture for the grinding of a workpiece with a minimum amount of wear and requiring a minimum of adjustment during use.

Another object is to provide an improved workpiece support for centerless grinding of any of a variety of workpiece sizes, wherein the support includes adapter elements which are releasable to conform to the support contour of the desired workpiece size and which are settable to retain the correct conforming contour. I

Other objects and various further features of the invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a side elevation view ofa grinding fixture of the invention, shown applied to a grinding machine and workpiece, to illustrate an external-grinding situation;

FIG. 2 is an enlarged side view partially broken-away and in section of the universal shoe used in the fixture of FIG. I;

FIG. 3 is a front view of the shoe as viewed from the aspect 3-3 of FIG. 2, part of the structure being broken-away and sectioned in the plane 30-311 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3 to illustrate the mounting for an individual supporting pin used in the universal shoe; and

FIG. Sis a side view similar to FIG. I ofa complete grinding fixture assembly for the grinding of an internal surface of a workpiece.

Briefly stated, the invention contemplates a universal fixture for the support of one among a variety of workpiece sizes to be centerless ground upon a given machine. The fixture adjustably carries a plurality of selectively locked spring-loaded pins which may be released to conform to the workpiece diameter, and which may be locked to retain the correct worksupport are for the particular workpiece. The principle of the invention is applicable to external-grinding and to internalgrinding situations.

In FIG I, a workpiece such as a bearing race ring is mounted in such a manner that it is supported by a universal shoe structure 12 and by a vertically adjustable front shoe or roll 14, in working relation with a grinding wheel 16. The front shoe 14 is vertically adjustably mounted on upright member or standard 18. Rotation of the workpiece as well as restriction of axial movement may be by a rotating magnetic chuck (not shown). Rotation of the workpiece is about axis 17 and the direction of its rotation and that of the grinding wheel are as shown by the arrows I9.

The universal shoe structure I2 is mounted on a supporting body 20. Body 20 in turn is fixedly-mounted on a radial slide 22, the position of which is controlled by a manually rotatable handle 21 and a lead screw 24. The radial slide, in turn, is mounted on an axially movable base plate 26 which is slidably mounted on a machine base 28. Base plate 26 provides axial movement of the universal shoe structure I2 to accommodate workpieces of different axial lengths. The upright member I8 is attached to the base plate 26. While the shoe I4 could be a duplicate of the universal shoe I2, we find that in many cases this is not necessary and in fact we prefer to employ a support roll, as shown, on a stub shaft that is selectively positionable by means 18' along a vertical adjustment slot 18".

The universal shoe structure includes a plurality of springloaded pins 32 across whose tips the workpiece 10 slides. The pins 32 extend generally radially, and are shown set for definition (at their tips) of a support are unique to the contour of the workpiece l0 and to the orientation of the shoe structure on supporting body 20. The tips of the pins 32 may be hard, as when made of carbide.

The universal shoe structure 12 is rotatably mounted about a pivot 34 between the arms of a U-shaped vertical slide 36. A stop 38 is provided to limit the rotation of the shoe structure 12. Limited pivot action of the shoe structure is suggested by the double-pointed arrow 40.

In FIG. 2, the supporting body 20 is shown provided with a cantilever arm or bracket 42, in which two pivot-control lock screws 44 are mounted. These screws act on the adjacent body surface or edge 46 of the pivoted shoe structure 12. The directional lines of force applied by the screws 44 straddle the pivot 34 so that the screws may both be used to prevent rotation of the shoe structure 12 as well as to control its orientation. The arm 42 is further provided with an advancing screw mechanism 48 for controlling the vertical position of the U- shaped vertical slide 36 along the directional of the arrow 50.

The screw mechanism 48 comprises an advancing screw 52 in threaded relationship with the cantilever arm 42 and having a nonthreaded end 54 captured in a bore 56 of the vertical slide 36. The end 54 is provided with a circumferential groove to receive a transverse retaining pin 58 set in slide 36, thus permitting rotation of the screw 52 accompanied by vertical control of slide 36. A locknut 60 is provided to lock the screw 52.

and may be secured in adjusted position, by setscrews 64. Mounting holes are provided in the supporting body 20 for mounting to radial slide 22.

The vertical slide 36 is shown in FIG. 3 with spaced arms or side members 66-68 between which the universal shoe structure I2 is pivotally mounted; the pivot 34 is seen to comprise two like stud or pin portions 34-34 on a common alignment. Studs 34-34 are respectively fixed to and carried by retaining or sideplates 70-7I, constituting part of the body structure of the universal shoe 12. Plates 70-71 are releasably clamped to each other by screws 82. At the upper end, screws 82 seat in plate 71 and engage threaded bores in an offset or shoulder portion 78 forming part of the plate 70; similarly, an offset or shoulder 80 forming part of plate 71 accommodates screws 82, at the lower end of the body of shoe 12.

The plates 70-7] jointly retain a plurality of assemblies to position pins 32. These assemblies, and therefore also pins 32, are clamped by setting screws 82. In each pin assembly (see FIG. 4), the pin 32 is the projecting head of the screw, threaded at into a triangularly or trapezoidally prismatic slide block 88, having convergent side faces 98. Adjacent pin assemblies abut along their convergent side faces, in alternating directions of convergence, thus placing the bases of oddnumbered blocks in bottoming reference to the sideplate 70, and the bases of even numbered blocks in similar but oppositely directed bottoming reference to the sideplate 71. The sideplate shoulders 7880 are provided with beveled undercuts I02l04 to match the adjacent slope of the adjacent slide block, as will be understood. Upon take up of the clamp screws 82, the slide blocks 88 jam with a lateral spread which is ultimately borne by the shoulders 7880, at undercuts 102- I04, at which point a small clearance, as at 100, remains at the apex (or short side) of each trapezoid; when clamped, a clearance 10! also exists between shoulders 78-80 and the adjacent surfaces of plates 71-70, respectively.

As previously noted, each pin 32 is independently movable and resiliently urged outwardly, to permit automatic contour conformation. The extent of such guided displacement is best seen in FIG. 4, wherein the slide block 88, when released from clamp action by screws 82, is movable between the outer posi- The vertical slide 36 is guided at 62 in supporting body 20 tion shown and an inner position of abutment with corresponding internal shoulder faces 86-87 on plates 70-7l; at the outer position shown, outer flanges 9697 on plates 70-71 determine the limit of projection of pins 32. Spring means 94, located in a bore 92 in each block 88 and located by pin means 96 on plate 71, constantly urge all pins to the projecting position; only by the described clamp action are pins 32 held back of the position shown in FIG. 4.

In the operation of the device, the pivot-lock screws 44 and the clamp screws 82 are loosened, and the pins 32 are brought into contact with an annular master gauge having an outside diameter corresponding to the desired final ground external diameter of the workpiece, the master gauge being magnetically chucked on the rotation axis 17 and in abutting reference to the grinding wheel 16. The radial-positioning slide 22 is advanced toward the master gauge, to an extent assuring positive retraction of all the pins 32, thereby confirming that each pin will contact the workpiece 10, with full conformation as to arcuate contour. If necessary, the shoe 14 is also vertically adjusted in reference to the gauge and axis. Thereupon, the lock screws 44 and 82 are set, to secure the pivot orientation of shoe 12 (about axis 34) and to clamp the pins 32. The gauge is then removed, and the grinding wheel 16 is traversed out of working position. The workpiece 10 may then be inserted as shown in FIG. 1, and the normal working traverse of grinding wheel 16 may be started.

By providing each of the pins 32 with an end tip, of different curvature, the likelihood of their contacting the same circumferential line on the workpiece is minimized. Alternatively, each of the pins may be so variously offset on its individual slide block 88 so as to avoid coincidence of their respective lines of contact with the workpiece. Both these techniques avoid excessive pressure along the same line of the workpiece.

FIG. shows a fixture assembly wherein the workpiece ring supported by a magnetic chuck (not shown) has an internal annular surface 106 to be ground by a wheel 105, having grinding contact at 108. The internal diameter of workpiece 10 is sufficiently large and the diameter of wheel 105 is sufficiently small that it can be readily accommodated within the inner volume of the workpiece.

A universal shoe 12 is again provided to support the external surface of the workpiece l0, and in the form shown shoe 12 provides the main vertical support of the workpiece. The shoe 12 is pivotally mounted at 109 on a plate 110 which is vertically positionable with respect to the machine frame 111 to accommodate variations in radial thickness and external diameter of the workpiece.

The workpiece 10 of FIG. 5 is further supported by a stabilizing roller shoe 14 which is angularly spaced from the pins 32. The shoe 14 is shown mounted on a traverse slide 112; slide 112 is guided for positioning movement along an arm 120 having pivoted reference (at 122) to the machine frame 111. The slide 112 is threaded at 114 to receive a lead screw 116 which is joumaled into the bracket end 119 (of arm 120) and controlled by handle 118. A stay arm or adjustable link 126 is pivotally related to the frame at 128 and may be clamped at 132 to the arm 120 at various selected locations along an adjustment slot 130, as dictated by the nature of workpiece 10. It will be understood that the upright 120 for supporting roller shoe 14 may be mountedwith the base plate 110, for their joint adjustable positioning, particularly for such axial positioning as may be necessary for handling workpieces having different axial lengths.

The of the device of FIG. Sis essentially the same as in FIG. 1, except that the universal shoe is brought into contact with the external diameter of the workpiece 10 instead of a master gauge. The pins 32 are depressed to align along a circle conforming to the workpiece outside diameter, and concentric with the workpiece drive axis. The shoe 14 is made to contact the surface at some angular spacing from the pins 32, such that cradled support of the workpiece and of the grind-reaction forces is sustained between wide angularly spaced stabilizing limits; the base of support is preferably a substantial obtuse angle, less than 180, as shown. After initiating the workpiece drive, the grinding wheel is traversed into working contact at 108, between the pins and the support 14. The contact point 108 may be anywhere between pins 32 and shoe 14 but is preferably placed just opposite the pins 32 closest to the shoe 14 to provide a firrn support of the workpiece, so that the internal surface 108 may be ground without deformation of the workpiece. 1

While the present invention has been described in conjunction with preferred embodiments, it may be modified without departing from the spirit and scope of the invention as defined by the claims.

We claim:

1. A fixture for centerless grinding of a rotated workpiece by a grinding wheel comprising a supporting body, a workpiece supporting shoe structure mounted on the supporting body and having a plurality of individually adjustable supporting pins mounted thereon, each pin being adapted to provide at one end a localized support for the workpiece, said structure being pivotally mounted to said supporting body about an axis generally parallel to the rotation axis of the workpiece, and means operative generally radially with respect to the workpiece rotation axis for positioning said plurality of supportingpins to align the work supporting ends thereof along the circumference of the workpiece.

2. A fixture for centerless grinding of a rotated workpiece by a grinding wheel, comprising: a supporting body, a workpiece-supporting shoe structure mounted on the supporting body and having a plurality of individually adjustable supporting pins mounted thereon, each pin being adapted to provide at one end a localized support for the workpiece, said structure including a pair of retaining plates spaced from one another with said pins positioned therebetween for holding the pins in adjustably fixed position with respect to each other, and said structure being pivotally mounted to said supporting body about an axis generally parallel to the rotation axis of the workpiece, and means operative generally radially with respect to the workpiece-rotation axis for positioning said plurality of supporting pins to align the work supporting ends thereof along the circumference of the workpiece.

3. The fixture as recited in claim 1 wherein the pivotal mounting for said shoe structure is provided by an upstanding bracket carried by said body, said bracket being adjustably positionable on said body.

4. The fixture as recited in claim 3 wherein said bracket is U-shaped with upstanding arms and wherein said retaining plates are pivotally mounted between said upstanding arms.

5. The fixture as recited in claim 4 wherein said bracket is a slide guided by said body for selective generally vertical positioning displacement, and advancing-screw means coacting between the supporting body and said bracket for vertical positioning control thereof.

6. The fixture as recited in claim 2 and further including a pair of lock screws mounted on the supporting body and acting on one of said retaining plates, said screws being positioned on said supporting body to apply lines of force on said one retaining plate straddling the pivot axis and providing controlled rotational orientation of the shoe structure.

7. The fixture of claim 2, wherein each supporting pin includes an elongated guide block guided for longitudinal displacement and from one end of which the pin projects, and spring means independently resiliently urging each pin in the longitudinally outward direction.

8. The fixture of claim 7, in which each guide block is generally trapezoidally prismatic, said blocks being retained by and between said plates and arranged along an alignment transverse to the longitudinal positioning alignments of said pins, the opposite converging sides of one guide block being in side-by-side wedging contact with the corresponding adjacent sides of the guide blocks adjacent thereto, adjacent blocks being arrayed in alternating opposite lateral directions of con vergence, to permit locking of said blocks when said plates are displaced toward each other, and clamping means coacting between said plates for drawing the same together.

9. The fixture as recited in claim 8, wherein the space between the retaining plates is so shaped to force a slight axial offset of said blocks.

10. The fixture as recited in claim 9, wherein each retainer plate is provided with a shoulder portion adjacent the opposite retainer plate, said shoulder portion having an effective height less than the effective width of said blocks measured between the parallel faces thereof, said clamping means being located at said shoulder portions.

11. The fixture as recited in claim 10, wherein said shoulder portions are provided with undercut beveled sides facing said blocks, the slope of said undercut sides substantially matching the slope of the adjacent block face.'

12. The fixture as recited in claim 1, and further including a second workpiece-supporting shoe circumferentially spaced from the first shoe structure, and mounted on said body for movement generally transverse to the adjustment axes ofsaid pins,

said second shoe being rotationally mounted on the fixture in the plane substantially coincident with that of said first shoe structure, the workpiece and the grinding wheel.

13. The fixture as recited in claim 12, wherein said body includes a base supporting plate supporting said shoe structure and movably mounted to the fixture for movement along a line in a plane substantially containing the shoe structure, the workpiece and the grinding wheel.

14. The fixture as recited in claim 1, and further including lock screw means eoacting between the supporting body and said shoe structure for selectively controlling the pivoted orientation of the shoe structure.

Claims (14)

1. A fixture for centerless grinding of a rotated workpiece by a grinding wheel comprising a supporting body, a workpiece supporting shoe structure mounted on the supporting body and having a plurality of individually adjustable supporting pins mounted thereon, each pin being adapted to provide at one end a localized support for the workpiece, said structure being pivotally mounted to said supporting body about an axis generally parallel to the rotation axis of the workpiece, and means operative generally radially with respect to the workpiece rotation axis for positioning said plurality of supporting pins to align the work supporting ends thereof along the circumference of the workpiece.

2. A fixture for centerless grinding of a rotated workpiece by a grinding wheel, comprising: a supporting body, a workpiece-supporting shoe structure mounted on the supporting body and having a plurality of individually adjustable supporting pins mounted thereon, each pin being adapted to provide at one end a localized support for the workpiece, said structure including a pair of retaining plates spaced from one another with said pins positioned therebetween for holding the pins in adjustably fixed position with respect to each other, and said structure being pivotally mounted to said supporting body about an axis generally parallel to the rotation axis of the workpiece, and means operative generally radially with respect to the workpiece-rotation axis for positioning said plurality of supporting pins to align the work supporting ends thereof along the circumference of the workpiece.

3. The fixture as recited in claim 1 wherein the pivotal mounting for said shoe structure is provided by an upstanding bracket carried by said body, saId bracket being adjustably positionable on said body.

4. The fixture as recited in claim 3 wherein said bracket is U-shaped with upstanding arms and wherein said retaining plates are pivotally mounted between said upstanding arms.

5. The fixture as recited in claim 4 wherein said bracket is a slide guided by said body for selective generally vertical positioning displacement, and advancing-screw means coacting between the supporting body and said bracket for vertical positioning control thereof.

6. The fixture as recited in claim 2 and further including a pair of lock screws mounted on the supporting body and acting on one of said retaining plates, said screws being positioned on said supporting body to apply lines of force on said one retaining plate straddling the pivot axis and providing controlled rotational orientation of the shoe structure.

7. The fixture of claim 2, wherein each supporting pin includes an elongated guide block guided for longitudinal displacement and from one end of which the pin projects, and spring means independently resiliently urging each pin in the longitudinally outward direction.

8. The fixture of claim 7, in which each guide block is generally trapezoidally prismatic, said blocks being retained by and between said plates and arranged along an alignment transverse to the longitudinal positioning alignments of said pins, the opposite converging sides of one guide block being in side-by-side wedging contact with the corresponding adjacent sides of the guide blocks adjacent thereto, adjacent blocks being arrayed in alternating opposite lateral directions of convergence, to permit locking of said blocks when said plates are displaced toward each other, and clamping means coacting between said plates for drawing the same together.

9. The fixture as recited in claim 8, wherein the space between the retaining plates is so shaped to force a slight axial offset of said blocks.

10. The fixture as recited in claim 9, wherein each retainer plate is provided with a shoulder portion adjacent the opposite retainer plate, said shoulder portion having an effective height less than the effective width of said blocks measured between the parallel faces thereof, said clamping means being located at said shoulder portions.

11. The fixture as recited in claim 10, wherein said shoulder portions are provided with undercut beveled sides facing said blocks, the slope of said undercut sides substantially matching the slope of the adjacent block face.

12. The fixture as recited in claim 1, and further including a second workpiece-supporting shoe circumferentially spaced from the first shoe structure, and mounted on said body for movement generally transverse to the adjustment axes of said pins, said second shoe being rotationally mounted on the fixture in the plane substantially coincident with that of said first shoe structure, the workpiece and the grinding wheel.

13. The fixture as recited in claim 12, wherein said body includes a base supporting plate supporting said shoe structure and movably mounted to the fixture for movement along a line in a plane substantially containing the shoe structure, the workpiece and the grinding wheel.

14. The fixture as recited in claim 1, and further including lock screw means coacting between the supporting body and said shoe structure for selectively controlling the pivoted orientation of the shoe structure.

Images