US3854252A

US3854252A - Work support shoes for centerless grinding machines

Info

Publication number: US3854252A
Application number: US00382872A
Authority: US
Inventors: A Lindsay; K Boalen
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-07-26
Filing date: 1973-07-26
Publication date: 1974-12-17
Anticipated expiration: 1991-12-17

Abstract

Work support shoes for a centerless grinding machine have shank and contact portions. The shank portions are arranged for mounting on the grinding machine and are made of a phenolic base material having a sufficient degree of flexibility to dampen vibrations imparted thereto. The contact portions are secured to and supported by the shank portions to contact and bear against a workpiece being ground and are made of a high density ceramic wear resistant material.

Description

United States Patent [191 Lindsay et a1.

WORK SUPPORT SHOES FOR CENTERLESS GRINDING MACHINES Inventors: Arwin 0. Lindsay, 13445 Oscar St.,

Sylmar, Calif. 91342; Kenneth C. Boalen, 1839A Verdugo Loma Dr., Glendale, Calif. 91208 Filed: July 26, 1973 Appl. No.: 382,872

US. Cl. 51/238 GG, 51/103 R Int. Cl B24b 5/34, B24b 41/06 Field of Search 51/103 R, 103 WH, 103 TF,

References Cited UNITED STATES PATENTS 12/1935 Gertiser 51/103 R 1/1956 Ernst 51/238 GG 5/1963 Humes 51/238 S [451 Dec. 17, 1974 3,449,867 6/1969 Lindsay 51/103 R FOREIGN PATENTS OR APPLICATIONS 581,618 7/1933 Germany 51/103 TF Primary ExaminerDonald G. Kelly Assistant Examiner-Marc R. Davidson Attorney, Agent, or Firm-Huebner & Worrel [57] 7 ABSTRACT 5 Claims, 11 Drawing Figures PAIENTH, iii. 1 H914 sum 1 or 2 WORK SUPPORT SHOES FOR CENTERLESS GRINDING MACHINES BACKGROUND OF THE INVENTION The present invention relates to work shoes for centerless grinding machines. Such work shoes function as guides for holding workpieces properly orientated while they are being ground in the grinding machine.

Heretofore, work shoes have been generally made of carbide tipped steel.- Unfortunately, such prior art shoes have been found to be subject to the drawbacks of excessive vibration and rapid wear of their carbide tips. Excessive vibration of the work shoes causes movement of the workpieces while they are being ground while excessive wear of the carbide tips causes gradual displacement of the workpieces from their properly orientated positions. Both of these drawbacks or disadvantages limit the precision of the grinding operation and consequently, the precision of the parts formed from the workpieces.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved work shoe for a centerless grinding machine which is not subject to the aforementioned disadvantages of prior art work shoes.

It is further an object of the present invention to provide improved work shoes as set forth characterized by having shank portions having a sufficient degree of flexibility to dampen vibrations imparted thereto by a grinding machine, and contact portions for supporting workpieces being ground made of wear resistant material so as not to be subject to excessive and/or uneven wear.

In accomplishing these and other objects, there is provided in accordance with the present invention work shoes for centerless grinding machines having shank portions and contact portions. The shank portions are arranged for mounting on the grinding machine and are made of phenolic base material having a sufficient degree of flexibility to dampen vibrations imparted thereto. The contact portions are secured to and supported by the shank portions in position to contact and bear against a workpiece being ground, and are made of high density ceramic wear resistant material.

Additional objects of the present invention reside in the specific construction of the embodiments of work shoes hereafter shown in the drawings and described in connection therewith.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a centerless grinding machine having a pair of work shoes according to the present invention mounted therein.

FIG. 2 is a side elevation view of the grinding machine of FIG. 1.

FIG 3 is a perspective view of one of the work shoes of the grinding machine of FIG. 1.

FIG. 4 is a perspective view of another embodiment of work shoe according to the present invention.

FIG. 5 is a perspective view of still another embodiment of work shoe according to the present invention.

FIGS. 6a 6c are side elevation views of the work shoe of FIG. 5 illustrating different curvatures of its contact surface.

FIG. 7 is a perspective view of yet another embodiment of work shoe according to the present invention.

FIG. 8 is a perspective view of a modified form of work shoe of FIG. 7.

FIG. 9 is a perspective view of an additional embodiment of work shoe according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in more detail, there is shown in FIGS. 1 and 2 a conventional centerless grinding machine generally identified by the numeral 10. The machine 10 includes a frame portion 11 having an offset magnet chuck l2 and a grinding wheel 13 mounted in a conventional manner thereon. A protective shield 14 is formed around the outboard side of the grinding wheel 13.

An upward projecting plate-like portion 15 is formed as part of the grinder frame 11. The plate 15 is positioned in alignment with the grinding wheel 13 and has its edge 16 adjacent the grinding wheel 13 shaped so that a workpiece 17 may be positioned thereabove in a proper orientation for grinding by 'the wheel 13. The magnetic portion 22 of the chuck 12 is positioned to hold the workpiece 17 in this grinding position.

A partially curved slot 18 is formed in the plate 15 adjacent the edge 16. The shape and curvature of the slot 18 conforms with the shape of the edge 16. Clamped to the plate 15 by bolts-nut combination 19 to extend therefrom towards the grinding position for the workpiece 17 are two shoe support arms 20. The arms 20 have slots 21 of uniform width formed along the greater portion of their lengths through which the bolts 19 extend. Formed in the outwardly positioned ends 23 of each of the arms 20 are holes through which the bolts of bolt-nut combinations 24 extend.

Clamped on the upper ends of each of the arms 23 by one of the bolt-nut combinations 24 are

work shoes

30 and 31. The work shoe 30, which is positioned to the left in FIG. 2, is shown on an enlarged scale in FIG. 3.

Referring to FIG. 3, the work shoe 30 has a base or shank portion 32 made up of a planar top 33 and a downwardly extending stem 34. The planar top 33 is rectangularly shaped and the stem 34 extends perpendicularly to the upper and lower surfaces of the top 33 across its width. The stem 34 is also preferably rectangularly shaped and is positioned relative to the top 33 so that the top 33 extends symmetrically to each side thereof. Thereby, the shank 32 defined by the stem 34 and top 33 has a T-shaped cross-section. A hole or opening 35, the axis of which extends substantially parallel to the planar top 33, extends through the stem 34. The hole 35 is dimensioned for receiving the bolt 24 and is centrally formed in the stem 34 so as to permit the stable mounting of the shank 32 on one of the support arms 20.

The shank 32 defined by the stem 34 and top 33 is formed of a single piece of phenolic base material having a sufficient degree of flexibility to dampen vibrations imparted thereto by the grinding machine 10. A suitable phenolic base material is described and has its properties set out in our U.S. Pat. No. 3,449,867, issued l7th June 1969 and is a paper based phenolic plastic employing a paper base bonded by a phenol formaldehyde resin of electrical grade. The use of such a phenolic base material for the shank 32 minimizes vibration and chatter of the shank and also minimizes transfer of kinetic energy thereby.

Adhesively secured by a layer of an epoxy resin adhesive 40 on the fiat upper surface of the shank top 33 is the contact portion 41 of the work shoe 30. The contact portion 41 has a flat bottom corresponding in shape to the upper surface of the shank top 33 and an inwardly curved or concave top contact surface 42. The contact surface 42 curves along only one axis, from its side edge 43 to its side edge 44, to have a curvature corresponding to the outer surface of the annular workpiece 17.

The contact portion 41 of the work shoe 30 is made of a single piece of a suitable high density low porosity wear resistant ceramic material. A suitable ceramic material is described and has its properties set out in the above-mentioned US. Pat. No. 3,449,867.

Referring again to FIGS. 1 and 2, the work shoe 31 there shown is identical to the work shoe 30 with the exception that the stem 34 of its shank is bent instead of being straight. Thereby, the shoe 31 may be mounted on the right positioned arm 20 with the lower part of the stem 34 aligned with the longitudinal axis of the arm 20 and the shoe contact portion 41 facing slightly to the left.

In operation of the grinding machine 10, the annular workpiece 17 may be ground or finished in the following manner. The work shoes and 31 are mounted on the upper ends of, the support arms 20 in the manner shown in FIG. 2 and the arms 20 are properly positioned and clamped in place by tightening the bolt-nut combinations 19. The workpiece 17 is positioned in the curved seat defined by the

shoes

30 and 31 in contact with magnetic clutch portion 12. The grinding wheel 13 is then driven counterclockwise (as viewed in FIG. 2) with the result that the workpiece 17 rotates in place and its outside periphery is. ground by the wheel 13.

A modified fonn of work generally identified by the numeral is shown in FIG. 4. The shoe 50 is constructed in a manner similar to the construction of the shoe 30 with the following exceptions. lts contact portion is made up of two identically shaped spaced apart support parts 51 instaed of one solid piece. The parts 51 each have substantially the same cross-sectional shape as the contact portion 41 of the shoe 30. The parts 51 are adhesively secured on opposite ends of the shank top 52 parallel to the shank stem portion 53. The portion 54 of the shank top 53 which extends between the contact parts 51 is elevated above the surfaces 55 upon which the parts 51 are mounted so as to provide vertical walls 56 which aid in supporting the contact parts 51 on the shank top 52.

FIG. 5 illustrates another embodiment of work shoe which is generally designated by the numeral 60. The shoe 60 is constructed like the aforedescribed work shoe 30 with the exception that the shank top 61 is formed as a continuation of the shank stem 62. The shoe contact portion 63 is dimensioned to be the same size as the shank top 61 for mounting thereto.

FIGS. 6a 6c are side views of the shoe 60 and illustrate that the shoe contact surface 64 which contacts a workpiece may be made of any curvature suitable for contacting the specific workpiece to be finished.

FIG. 7 illustrates a work shoe generally identified by the numeral 70. The shoe is constructed like the shoe 60 with the exception that the shank top 71 is concavely shaped and the lower portion of the shoe contact portion 72 has a curvature corresponding to the shank top 71 so as to securely interfit therein.

FIG. 8 illustrates a work shoe generally identified by the numeral 80. The shoe is constructed like the shoe 70 with the exception that the shank top 81 for receiving the shoe contact portion 82 is V-shaped in cross-section. The contact portion 82 is shown secured in the \/-shaped top 81 in a position tilted from the longitudinal plane of the shank stem 83.

FIG. 9 illustrates a work shoe generally designated by the numeral wherein the top 91 of the shoe shank 92 and the contact portion 93 adhesively secured thereon are arranged to define a V-shape for cradling a workpiece.

Throughout the specification and drawings the centerless grinding machine '10 has been referred to and illustrated for the external grinding of a workpiece. However, the machine 10 can also be utilized to accomplish internal grinding of a workpiece by a rearrangement of the grinding medium without departing from the spirit of the invention relating to the work support shoes.

Although we have herein described our invention in what we have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of our invention.

We claim:

1. For use in a centerless grinding machine having a grinding wheel, a plate secured to a frame of the machine in general alignment with the circumferential grinding surface of said wheel and extending transversely with respect to the wheel axis, said plate being adapted to be in alignment with a workpiece to be ground by the wheel, chuck means to hold the workpiece between said plate and said wheel in the grinding position, said plate being adapted to extend generally laterally and downwardly of the workpiece in the grinding position, support arms adjustably mounted on said plate and having inner ends adapted to extend toward the workpiece in the grinding position, work support shoes having outer ends adjustably mounted to respective inner ends of said support arms;

the improvement comprising:

said work shoes each having a workpiece contact portion and a shank portion,

each shank portion having an outer and an inner end,

said outer ends of said shank portions defining the outer ends of said work support shoes,

each shank portion being made of a phenolic base material having sufficient degree of flexibility to dampen vibrations imparted to its outer end by the grinding machine during the grinding operation whereby vibration of the inner end is substantially eliminated,

each contact portion being mounted on an inner end of a respective shank portion,

the periphery of the inner end of the shank portion being at least substantially coextensive with the periphery of the contact portion, and each contact portion having an inwardly facing surface arranged for contacting and supporting the workpiece,

said contact portion being made of a high density.

low porosity, wear resistant ceramic material.

2. The invention according to claim 1 in which:

6 said contact portion is secured to said shank portion lower end of the T leg and inner end forming the by an epoxy resin adhesive. T crossbar, mvennon accordmg to F 2 Whlch: said contact portion forming an upper portion of the the inner end of the shank portion and the part of the T crossbar contact portion secured thereto are shaped to in- 5 terfit 5. The invention according to claim 4 in WhlChI The invention according to claim 3 in whichZ the shank portions have substantially rectangular sursaid shank portion has a T-shaped cross section, the faces between the inner and Outer endsouter end of the shank portion terminating at the

Claims

1. For use in a centerless grinding machine having a grinding wheel, a plate secured to a frame of the machine in general alignment with the circumferential grinding surface of said wheel and extending transversely with respect to the wheel axis, said plate being adapted to be in alignment with a workpiece to be ground by the wheel, chuck means to hold the workpiece between said plate and said wheel in the grinding position, said plate being adapted to extend generally laterally and downwardly of the workpiece in the grinding position, support arms adjustably mounted on said plate and having inner ends adapted to extend toward the workpiece in the grinding position, work support shoes having outer ends adjustably mounted to respective inner ends of said support arms; the improvement comprising: said work shoes each having a workpiece contact portion and a shank portion, each shank portion having an outer and an inner end, said outer ends of said shank portions defining the outer ends of said work support shoes, each shank portion being made of a phenolic base material having sufficient degree of flexibility to dampen vibrations imparted to its outer end by the grinding machine during the grinding operation whereby vibration of the inner end is substantially eliminated, each contact portion being mounted on an inner end of a respective shank portion, the periphery of the inner end of the shank portion being at least substantially coextensive with the periphery of the contact portion, and each contact portion having an inwardly facing surface arranged for contacting and supporting the workpiece, said contact portion being made of a high density, low porosity, wear resistant ceramic material.

2. The invention according to claim 1 in which: said contact portion is secured to said shank portion by an epoxy resin adhesive.

3. The invention according to claim 2 in which: the inner end of the shank portion and the part of the contact portion secured thereto are shaped to interfit.

4. The invention according to claim 3 in which: said shank portion has a T-shaped cross section, the outer end of the shank portion terminating at the lower end of the T leg and inner end forming the T crossbar, said contact portion forming an upper portion of the T crossbar.

5. The invention according to claim 4 in which: the shank portions have substantially rectangular surfaces between the inner and outer ends.