US3098330A - Abrading device - Google Patents

Description

United States Patent 3,098,339 ABRADING DEVICE Dirck J. Olton, Loutlonville, N.Y., and Russell P. Hook, Sutton, Mass, assignors to Norton Company, Worcester, Mass, a corporation of Massachusetts Filed Nov. 22, 1961, Ser. No. 154,149 6 Claims. (Cl. 51-197) The invention relates to an abrading or lapping device, and more particularly to an improvement for abrading or lapping devices comprising means for supporting and uniformly tensioning a sheet of abrading material upon the rotatable lapping head or plate of a lapping machine or other apparatus for abrading a work piece.

Due to the fact that certain abrading operations and particularly lapping operations remove only a very small amount of material from the surface of a work piece bemg abraded or lapped, sheet material with an abrasive surface such as that commonly known as a coated abrasive sheet may be used for certain abrading or lapping operations in place of a relatively more expensive solid abrasive lap of the type well known in the art with the additional advantage that sheets of abradant of different grades are readily changeable as required and the further advantage that the normal requirement for truing a solid abrasive lap periodically is eliminated simply by the replacement of a worn sheet of abradant with a new sheet of abradant as required. Moreover, replacement sheets of abradant may be stored in less space and may be handled more readily than solid abrasive laps of substantial thickness and very substantial weight.

While it is well known in many applications to secure sheets of abradant such as coated abrasive sheets to backing surfaces by means of suitable adhesives in order to properly secure the sheet material, the substitution of a new sheet of abradant for a worn sheet or a sheet of a different grade is rendered more difficult by the fact that the sheet to be replaced is secured by an adhesive and it is extremely difficult to be certain that the layer of adhesive by means of which the new sheet is secured is of uniform thickness throughout the entire area of the sheet secured thereby.

In contrast to the prior art teachings, the instant invention contemplates an arrangement for supporting and tensioning a sheet of abradant adjacent to a suitable supporting surface so that the proper contour of a sheet of abradant is assured by its direct engagement over its entire area with a precisely formed supporting surface and so that a sheet of abradant may be released from the supporting surface simply by releasing the tensioning means therefor in the absence of an adhesive coating between the sheet of abradant and the supporting surface.

One example of a machine to which the present invention could be applied is illustrated in US. Patent 2,695,479 to Herbert S. Indge showing a lapping machine in which the abrasive lap could be replaced by a metal lap with a suitable surface for supporting a sheet of abradant additionally provided with means for clamping and radially tensioning a sheet of abradant as described below and illustrated in the accompaniyng drawing.

It is therefore one object of the invention to provide an abrading device for use on abrading machines such as lapping machines or the like whereby abrasive sheets may be supported and secured for use in performing abrading or lapping operations.

Another object of the invention is to provide an abrading device comprising an attachment for abrading machines such as lapping machines operable to uniformly tension a sheet of abradant supported in engagement with a suitable supporting surface therefor.

Still another object is to provide an abrading device for supporting and uniformly tensioning a sheet of abradant including a plurality of coating tensioning. devices operable in unison.

A further object is to provide an abrading device for supporting and uniformly tensioning a sheet of abrasive releasable for the insertion of sheets of abradant of different grades as required.

Other objects and advantages of the instant invention will become apparent from consideration of the following description and from the showing in the accompanying drawing wherein:

FIG. 1 is a plan view of the preferred embodiment of the abrading device with a sheet of abr-adant supported and uniformly tensioned thereon, and

FIG. 2 is a sectional view through the preferred embodiment of the abrading device taken approximately on line 22 of FIG. 1 showing this device as it would appear when incorporated on :a conventional lapping machine, with portions of such a lapping machine indicated in FIG. 2 by phantom lines.

As illustrated in the drawing, the abrading or lapping device preferably comprises a circular backing plate or lap 1E arranged to be mounted upon a support rotatable about a vertical axis such as that provided in a conventional lapping machine. Reference may be had to US. Patent 2,695,479 referred to above for additional details of a lapping machine of the general type to which this invention may be applied.

The backing plate or lap 16 may be, but is not necessarily, provided with a central hole 12 therethrough, its configuration in this respect generally depending upon the configuration of the lapping machine on which it is mounted.

As shown in FIGS. 1 and 2, the backing plate 10 is provided with :a plurality of spaced parallel guides 13 and 13a which may be secured to the backing plate 10 by threadable engagement therewith as shown in the drawing. Each pair of guides 13 and 13a supports one of a plurality of radially movable segmental members 20 each provided with a pair of parallel holes for this purpose. Each pair of guides 13 and 13a precludes angular displacement of the movable member 20 supported thereby relative to the backing plate 10 and limits radial movement of the associated movable member 20 by a suitable limit stop such as the stop nuts 14 illustrated in the drawing.

The backing plate 19 is also provided with a circumferential support comprising a tongue 15 extending around the periphery of the backing plate 10* as shown in the drawing which may be either secured to or formed integrally with the backing plate 10. Each of the movable members 29 is provided with an inwardly opening slot or groove 17 with opposed surfaces mating with the opposed surfaces 16 and 16a of the tongue 15 for sliding engagement therewith. The circumferential support comprising tongue 15 thus provides a common supporting means for the respective members 2! restraining the respective members 29 against vertical movement with the upper surfaces of the respective members positioned coplanar with the upper surface of the backing plate 10 while permitting radial movement of the respective movable members Ztl along the respective pairs of guides 13 and 13a. As noted above, the amount of radial movement of the respective members 20 is limited by the respective nuts 14- threadably engaging and thereby adjustable on the respective guides 13a.

Each of the movable members 29 is provided with at least one pair of oppositely sloped cam engaging or following surfaces 22. As illustrated in FIG. 1, each member 20 is provided with two pairs of such cam engaging surfaces. Precise coplanar alignment between the top surface 26 of the backing plate 10' and the flat planar upper surfaces 24 of the respective movable members can be assured by machining all of the surfaces 24 and the surface 26' simultaneously after the respective members 20 have been assembled on the backing plate 10. In this manner, this device is provided with an uninterrupted flat surface for properly supporting a sheet of abradant material 28.

Each of the movable members 20 is provided with a clamping element 30 for engaging the outer edge portion of a sheet of abradant material, each releasably secured to the associated movable member 20 by a plurality of screws 32 and washers 34 disposed as shown best in FIG. 2 with the screws 32 extending through elongated slots 36 in each clamping element 30 and threadably engaging suitable holes in the respective members 20.

In the embodiment of the instant invention illustrated in the drawing, the backing plate 10 is shown as comprising an annular ring with a central opening therethrough. Accordingly, a clamping ring 38 is provided for securing the inner edge of the sheet of abradant material to the backing plate 10 by means of a plurality of screws 40 threadably engaging the backing plate 10. In applications where the backing plate 10 comprises an uninterrupted circular disc, the sheet of abradant need not be provided with a central opening therethrough. Hence the clamping ring 38 and the attachment screws 40 therefor could be eliminated without affecting the function of the tensioning means described below.

A unitary rotatably mounted camming member 44 having a central opening 46 therethrough is fitted into an annular recess 48 formed adjacent to the periphery of the backing plate 10 and provided with a shoulder 50 engaging the surface of the opening 46 in the annular member 44 so that the member 44 is maintained con centric of the backing plate 10.

The member 44 is maintained in operative relation to the backing plate 10 by an annular ring 52 secured to the backing plate 10 by a plurality of screws 53 and forming the upper wall of the recess 48. The upper surface 54 of the annular ring 52 is coplanar with and in fact forms an extension of the supporting surface 26 of the backing plate 10 and a precise coplanar relationship is conveniently established by a grinding or other machining operation after the annular ring 52 is secured to the backing plate 10, preferably by the machining operation referred to above for establishing the proper relationship between the surface 26 and the upper surfaces 24 of the respective members 20.

The rotatable member 44 is provided along its outer periphery with a plurality of spaced pairs of camming surfaces 56 disposed for engagement with the respective pairs of cam engaging surfaces 22 provided on the radial- 'ly movable members 20. With this arrangement, rotation of the rotatable member 44 in either direction relative to the backing plate 10 produces sliding movement of the respective members 20 radially outwardly of the backing plate 10 in unison.

A means for rotating the camming member 44 in either direction is also mounted within or supported by the backing plate 10. As illustrated in FIGS. 1 and 2, the means for rotating the member 44 comprises a short section of gear teeth 58 formed along the inner surface 46 of the camming member 44, a pinion 60 meshing with the gear teeth 58 and mounted on a shaft 62 which may be journal-led in the backing plate 10, a worm gear 64 secured to the lower end of shaft 62 within an opening 66 in the backing plate 10, a worm 68 secured to a rotaable shaft 70, also journalled in the backing plate 10, and disposed in engagement with the worm gear 64, and a shaped head 72 provided on the outer end of shaft 70 for engagement with a suitable crank or wrench operable to rotate the shaft 70 and thereby the rotatable camming member 44, through the interconnected driving elements described above collectively comprising a unidirectional drive operable in either direction in response to rotation of the shaft 70.

Operation of the device comprising the instant invention first requires rotation of the shaft 70 to rotate the worm 68, the Worm gear 64, the shaft 62, the gear 60 and the rotatable member 44 so that the camming sur faces 56 are not biased into engagement with the cam engaging surfaces 22. If there is a sheet of abradant material 28 installed on this device, such rotation of the rotatable member 44 is effective to release all of the tension applied to the sheet of abradant material and to allow the respective movable members 20 to return to their original innermost positions. The respective screws 32 are loosened so that the clamping elements 30 may be moved outwardly relative to the respective movable members 20 the length of the elongated slots 36 through the clamping elements 30 in order to clear the outer edge of the sheet of abradant. In embodiments of the instant invention in which the sheet of abradant material 28 is provided with a central opening as shown in the drawing, the clamping ring 38 is released by removing the screws 40, and then removed from the backing plate 10.

A sheet of abradant material 28 supported upon the upper surface 26 of the backing plate 10 can now be removed and replaced with another sheet of abradant material 28. The replacement sheet of abradant material 28 is then deposited upon the upper surface 26 of the backing plate *1!) with its central opening, if any, concentric of the central hole :12 of the backing plate 10. In embodiments of the instant invention wherein the backing plate 10 comprises an uninterrupted circular disc, a sheet of abradant material 28 without a central opening therethrough may be positioned concentric of the movable segments 20.

In embodiments of the instant invention wherein the clamping ring 38 is used, this ring is then replaced and secured to the backing plate '10 by the screws 40 in order to clamp the inner edge portion of an annular sheet of abradant material 28 to the annular backing plate 10. Next, each of the clamping elements 30 is then moved inwardly individually the length of the elongated slots 36 so that it is disposed over a portion of the outer edge of the sheet of abradant material 28. With each clamping element 30 so disposed and with its associated movable member 20 held against the periphery of the backing plate .10, the clamping screws 32 for that clamping element are tightened to clamp the outer edge portion of the sheet of abradant material 28 to each of the movable members 20.

When all of the clamping elements 30 have been secured in the manner described above, a wrench or crank engaging the head 72 on the shaft 70 is turned in either direction to rotate the worm 68, the worm gear 64, the gear 60 and thence the rotatable camming member 44 in order to bias the respective camming surfaces 56 into engagement with the associated cam engaging surfaces 22 on all of the movable members '20 in order to move all of the slidably movable members 20 outwardly equal amounts relative to the backing plate 10 in unison so that the sheet of abradant material 28 is uniformly tensioned over its entire working surface. The respective movable members 20 are maintained in fixed angular relationship to the backing plate r10 during this radial movement by the respective pairs of parallel guides 13 and 13a engaging these movable members.

In use the abrading device of the instant invention can be mounted on a lapping machine as shown in phantom lines in FIG. 2 of the drawing, wherein the various elements so illustrated correspond to various elements of the lapping machine illustrated in US. Patent 2,695,479 referred to above to which reference may be had for additional details not illustrated in FIG. 2. As shown in FIG. 2, the backing plate 10 is secured to and rotatable with a member supported by a suitable base not shown for rotation in a predetermined direction about a first vertical axis. A rotatable cage 82 with apertures therethrough for receiving a plurality of work pieces W is rotatably supported in a plane parallel to and a predetermined distance above the surface of the abradant material 28 upon a bushing 84 adjustably secured to a stationary shaft 86 which may be disposed on a second vertical axis. While the first and second vertical axes referred to above may be coincident as suggested by the showing in FIG. 1, they may alternatively be offset so that the cage 82 is disposed eccentric of the base plate in the manner illustrated and described in detail in U.S. Patent 2,695,479. The cage 82. may conveniently be rotated by driving elements engaging a gear 88 on the outer periphery of the cage 82. Where necessary, Weights may be applied to the upper surfaces of the work pieces W by any suitable arrangement such as that illustrated in Patent 2,695,479 in order to enhance the abrading operation.

It will be seen that there has been provided by this invention apparatus in which the objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments and changes may be made of the instant invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative rather than in a limiting sense.

What is claimed is:

1. An abrading device comprising, a backing plate, supporting means disposed adjacent the perimeter of said backing plate, a plurality of members supported by and outwardly movable on said supporting means, a sheet of abradant supported by said backing plate, means to clamp said sheet of abradant to each of said movable members, and means mounted adjacent said backing plate operable to move all of said movable members outwardly in unison by coordinated amounts to uniformly tension said sheet of abradant.

2. An abrading device comprising, a backing plate, a supporting means including a continuous tongue extending outwardly from and disposed around said backing plate, a plurality of outwardly movable members supported on said supporting means, all of said outwardly movable members being provided with cam engaging surfaces, a sheet of abradant supported on said packing plate, means to clamp said sheet of abradant to each of said outwardly movable members, and means mounted upon said backing plate including a rotatable member with cam surfaces operable to move all of said movable members outwardly in unison by coordinated amounts to uniformly tension said sheet of abradant.

'3. An abrading device comprising, a circular backing plate, a supporting means disposed around and extending outwardly from said backing plate, a plurality of radially movable members mounted on said supporting means, all of said movable members being provided with cam engaging surfaces, a circular sheet of abradant with a central hole therethrough supported on said backing plate, means to clamp the inner edge of said sheet of abradant to said backing plate, means to clamp said sheet of abradant to each of said movable members adjacent the outer edge thereof, and means mounted upon said backing plate operable to move all of said movable members outwardly an equal amount in unison to uniformly tension said sheet of abradant.

4. An abrading device comprising, a circular backing plate, a circular support disposed about the periphery of the backing plate, a plurality of spaced parallel pairs of elongated guide means extending outwardly from said backing plate, a plurality of radially movable members respectively supported in sliding engagement with the respective pairs of guide means and in mating engagement with said circular support, all of said radially movable members being provided with cam engaging surfaces, a sheet of abradant supported on said backing plate, means to clamp said sheet of abradant to each of said radially movable members, rotatable means mounted adjacent said backing plate including spaced camming surfaces operable against the respective cam engaging sur faces to move all of said movable members outwardly an equal amount in unison to uniformly tension said sheet of abradant.

5. An abrading device comprising, a backing plate, a projecting tongue disposed around the perimeter of said backing plate, a plurality of guide means extending outwardly from and spaced around said backing plate, a plurality of members mounted slidably on said guide means each having a groove disposed in mating engagement with said tongue, all of said movable members being provided with identical cam engaging surfaces, a sheet of abradant on said backing plate, means to clamp said sheet of abradant to each of said slidable members, a unitary camming means rotatably mounted within said backing plate and disposed for engagement with the respective cam engaging surfaces to move all of said slidable members outwardly equal amounts in unison to uniformly tension said sheet of abradant, and means including a rotatable worm and worm gear housed in said backing plate operable to rotate said unitary camming means.

6. An abra'ding device comprising, a circular backing plate, a supporting means projecting from the circumference of said backing plate, spaced pairs of parallel guide means extending outwardly from said backing plate, a segment slidably movable on each pair of parallel guide means and disposed in engagement with said continuous guide, all of said slidably movable segments being provided with identical cam engaging surfaces, a sheet of abradant supported upon said backing plate, means to clamp said sheet of abradant to each of said slidably movable segments, a unitary circular member rotatably mounted upon said backing plate having a plurality of spaced cams on the periphery thereof for engaging all of the cam engaging surfaces on the respective slidably movable segments, rotating means engaging a coacting surface of said unitary circular member, a rotatable worm and worm gear mechanism mounted in said backing plate for rotating said rotating means, and said unitary circular member to move all of said slidably movable segments an equal amount in unison to uniformly tension said sheet of abradant.

References Cited in the file of this patent UNITED STATES PATENTS 905,464 Sadler Dec. 1, 1908

Claims (1)

1. AN ABRADING DEVICE COMPRISING, A BACKING PLATE, SUPPORTING MEAND DISPOSED ADJACENT THE PERIMETER OF SAID BACKING PLATE, A PLURALITY OF MEMBERS SUPPORTED BY MEANS AND OUTWARDLY MOVABLE ON SAID SUPPORTING MEANS, A SHEET OF ABRADANT SUPPORTED BY SAID BACKING PLATE, MEANS TO CLAMP SAID SHEET OF ABRADANT TO EACH OF SAID MOVABLE MEMBERS, AND MEANS MOUNTED ADJACENT SAID BACKING PLATE OPERABLE TO MOVE ALL OF SAID MOVABLE MEMBERS OUTWARDLY IN UNISON BY COORDINATED AMOUNTS TO UNIFORMLY TENSION SAID SHEET OF ABRADANT.

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