US2279278A - Grinding disk - Google Patents

Description

' I. R. SHUE GRINDING DISK April 7, 1942.

Filed Mafch 17', 1939 :5 Sheets-Sheet 1 'April 7, 1942. 1; R. SHUE I 2,279,278

GRINDING DISK Filed March 17, 1939 s Sheets-Sheet 2 April 7, 1942. 1. R. SHUE 2,279,278

GRINDING DISK Filed March 17, 1959 3 Shets-Sheet 3 JkMnZor Patented Apr. 7, 1942 GRINDING DISK Ingle R. Shue, Beloit, Wis., assignor to Gardner Machine Company, South Beloit, Ill-., a corporation of Illinois Application March 17, 1939, Serial No. 262,365

4 Claims.

The invention relates generally to grinding means; and more; particularly to a grinding disk, one face. of which is utilized for grinding.

The general object of the invention is to provide a. new and improved grinding disk so constructed as to provide for expansion due to heat such as. would cause the grinding face to become distorted out of the plane. to which is was originally trued, the structure of the disk being such that a large factor of safety is provided so that it. may be operated at high, speeds and under heavy'loads.

More specifically, it is an object to provide a rinding. disk having slots to provide for expansicn of the disk due to; heat and thus avoid dis- 1 which:

Figure l is a perspective View, partially broken away, Of a rinding disk embodying the features of the invention.

Fig. 2 is a view similar to. Fig, 1 showing a modified form of grinding disk.

Fig. 3. is a view similar to Fig. 1 but showing another modified form of the grinding disk.

Fig. 4. is a view similar to Fig. l of another modified form of grinding disk comprising a plurality 0f; separate segments.

Fig. 5 is a perspective View of a mold for making disks of the character shown in Fig. 1.

Fig. 6 is a transverse section of the mold shown in Fig. 5.

In present grinding practice, grinding disks are often rotated at such high speeds and so much stock removal i effected therebythat a, large amount of heat is generated and the disk tends to expand. Such disks are annular in form and are mounted on a metal supporting, wheel, the grinding being done by the face of the wheel. It has been noted that when the heat reaches such an extent that the whole mass of the disk and the supporting wheel have a considerable temperature rise, the disk tends to raise in its central portion and assume a somewhat conical form. Such distortion of the disk is due to the fact, that the disk proper has a different coeflicient of expansion from that of the supporting wheel and, since the disk is bolted to the supporting wheel at a plurality of points distributed over the entire area thereof, the difference in expansion between the supporting wheel and the disk proper causes the latter to assume a conical form.

The accuracy of grinding operations performed by the disk is obviously affected by such distor-'- tion of the disk. A disk'is usually trued before it has become thoroughly heated. Thus when the expansion occurs, the distortion causes the grinding face of the disk to Vary from the original plane to. which such face was trued.

It is therefore desirable to construct the disk in a manner to eliminate such conical distortion. It has been found that, by placing narrow radially extending slots in the disk, it can expand the necessary amount without producing a distortion of the face of the disk. However, such slots would tend to weaken the disk unless the disk also embodied such structure as would rigidly tie allparts of the disk together. The need for physical strength in the disk is particularly great because of the generation of heat. In other words, if the Work done on a disk is sufficient to produce such heat as wouldcause undue expansion, then such, work also places severe stresses on the disk, thereby requiring a structure not only compensating for any weakening produced by the means for eliminating undesirable expansion, but also astructure capable of carryingthe highstresses.

Any slots or holes in the grinding face of the disk also affect the cutting action of the disk. It is therefore necessary to arrange the radial slots herein disclosed in such a manner that the illustrated in Fig. 1 of the drawings, the supporting wheel-is indicated at I t and is of the type which is. adapted tobe rigidly secured to the spindle of a grinding machine. The grinding disk, indicated generally at H, is provided with a plurality of; radially extending slots l2 which provide space for the expansion of the disk and thereby avoid distortion of the grinding face. For

devices.

cause of the fact that they divide it into sections,

the disk is so made as to include structure to compensate for such weakening effect as well as to provide a maximum ofstrength since disks of this character are subjected to heavy stresses during operation, Every grinding disk is provided with means for attaching it to the sup porting wheel. In this instance nuts l4 are embedded in the rear portion of the disk by which the disk may be attached to the supporting wheel by bolts extending therethrough. Anchoring devices of this character are preferablydistributed throughout the entire area of the disk.' Since that portion of the thickness of the disk in which the anchoring devices are embedded is relatively small, there is no necessity for having the radial slots l2 extend into that portion of the thickness of the disk. Consequently theslots ll have a depth substantiallyequal to the thick ness of the usable portion of the disk.

' Since the slots divide the usable portion of the disk into sections which are not integrally con nected to the adjoining sections themselves, the portion of the disk in which the anchoring devices are embedded is made of sufficient strength to rigidly tie these sections together. Thus the disk may be said to be divided into a front layer IS in which the radial slots are located, and a rear layer of unitary construction which serves to tie all parts of the disk together as a unit. To give the rear layer sufficient strength to per-'- form this function, it is preferably reenforced as by means of a wire mesh l5 embedded therein. The mesh preferably is coextensive with the area of the whole disk and is located between the nuts l4 andthe rear face of the disk. Thus stresses on any section of the disk will be transmitted throughout the disk by the rear layer and will be distributed uniformly over all the anchoring greater thickness than the disk shown in Fig. 1.

With a greater thickness the slots, indicated in this instance at 2B, are so arranged that the us-. able portion of the disk itself has greater strength. Thus each slot may have a depth substantially half the thickness of the usable portion of the disk, and the slots may be arranged in two rows, one above the other, with the slots in one row in staggered relation to the slots in the other row. The rear layer of the disk is constructed similarly to the disk shown in Fig 1. Thus while the rear layer rigidly ties the various sections of the disk togetherat the rear face thereof, the staggered relation of the slots in the two rows provides a tyingof the respective sections to each other adjacent the front face of the disk so that theweakening effect of the slots is much less than if each slot extended t e By such construction each section befull thickness of the usable portion of the disk.

Since the slots materially affect the cutting action of the disk, it is desirable to have the lower or rear edge of the slots in the front or upper row located in substantially the same plane, indicated by the dash and dot line 2|, as the front edge of the slots in the lower or inner IOW. g

While the slots in the two rows may have their adjacent edges located in exactly the same plane, they may, if desired, overlap slightly and extend beyond such plane, as shown in Fig. 3. Thus,

whilethere may be a slight change in cutting effect for asinall part of the thickness of the disk,.there is ample provision made for expansion at all times throughout the wearing of the disk.

In cases of disks of large diameter it is common practice to make the disk in a plurality of separate segments, each segment being of convenient size to mold and to handle. The segments are mounted on a unitary supporting wheel with a smallspace between each segment so that each segment 'may be accurately positioned. Such space obviously provides room for expansion but as a rule the spaces are insufficient in number to'entirely eliminate undesired ex-' pansion. For that reason additional space is provided for expansion bymeans of radial slots. In Fig. 4 I have illustrated a segmental type of disk embodying the features of the invention. Thus the disk comprises a plurality of segments, each indicated generally at 25, the disk* in this case comprising four such segments. The space between the respective segments is indicated at 26. Each segment is constructed in a manner similar to the disk shown in Fig. 1. Thus a rear layer 21 is provided which extends over the whole-area of the segment andconstitut'sfthe 21 is embedded the reenforcing means comprising wire mesh 28 and the anchoring devicescornprising the nuts 29.

T The front layer, constituting the usable portion of the disk, is provided with radial slots suilicient in number and size to compensate and provide room for expansion due'to heat. In the present instance there is provided a plurality of radial slots 30 which extend from the center hole in the disk throughto the periphery thereof. Because of the large sizeof each segment it may also be desirable to provide further slots 3| which extend fromthe point midway between the center and periphery of the disk out to theouter periphery. Thus the radial slots 30 and 3|, t0-

. gether with the space between the various segments, provide ample room for expansion of the disk due to heat. Moreover, in each segment the sections of the disk between the respective slots are rigidly tied together by means of the rear layer 21 and its reenforced construction, so that the stresses on any section within a segment is uniformly distributed over all the anchoring devices within that segment The shorter form'of slots, such as those shown at 3|, may also be used in disks of "the forms shown in Figs. 1, 2 and 3. v

The heat expansion slots shown in the various forms of the invention need not be of any great width since the expansion due to heat is of relatively small dimension. Moreover, it is preferable not to make the slots of any great-width in order thatthe work in passing over the surface of the disk may not be caught in such slots. In practice these slots are preferably 1 61703 2 'of an inch in Width." l T In Figs. and 6 I have disclosed a mold utilized in the method of making disks of the character herein disclosed. The particular mold shown in Figs. 5 and 6 is arranged for making disks of the character shown in Fig. 1. The mold comprises a base plate 30 adapted to be placed on the platen of a press. Surrounding the base is a ring 4! and mounted centrally f the base is a core 62.

In the process of making the disk a wire mesh 43 cut to fit the mold is first placed on the base plate, and the anchoring devices are placed thereover. Molding material is then spread over the Wire mesh and tamped so that the mesh and anchoring devices are thoroughly embedded therein. This constitutes the rear layer of the disk. To form the radially extending slots in the disk, bars or strips M are placed over the rear layer. Preferably such bars are supported at their inner ends by the cores Al -2 and extend outwardly through the ring M for support thereby. Abrasive material mixed with a bond is then filled into the mold, completely covering the bars id and extending to a height considerably thereover; for example, to the level shown by the line ii"; in Fig. 6. The abrasive material is then pressed, the compacting being carried only down to a level above the upper edge of the bars id, for instance, to the level indicated by the line This leaves aslight covering over the bars and consequently over the slots, but it is n that the platen of the press does not tact the bars it. Thus the entire pressure is to the abrasive material and none is supported by the bars.

To remove the disk from the mold, the bars t l are first withdrawn outwardly and then the disk itself may be removed from the mold in the usual manner and undergo any further treatment desired. The bars it thus provide the radially extending slots in the disk.

It is obvious that in the process of making the disks shown in Figs. 2 and 3, or the disk shown in Fig. 4, other bars located at different heights or of different lengths may be set into the mold to produce the correspondingly located slots.

From the foregoing description it will be apparent that I have provided a grinding disk which is so constructed as to provide space for expansion of the disk due to heat so that the grinding face of the disk will not become distorted out of its plane. The disk, however, is of great strength because of the fact that the various sections of the disk between the slots are rigidly held together by a reenforcing layer at the rear of the disk coextensive with the area of the disk. The stresses exerted on each secor additional slots may also be provided which are located only in the outer portion of the disk, as shown in Fig. 4.

I claim as my invention:

1. A grinding disk adapted to be detachably secured to a supporting wheel comprising, in

combination, a front layer having a plurality of radially extending slots arranged in two series, one series being in the front part of the front layer and the other series being in the rear part of the front layer with the slots in one series in staggered relation to the slots in the other series, and a rear layer having reenforcing means rigidly supporting the disk as a whole and tying all parts thereof together as a unit.

2. A grinding disk of the character described comprising, in combination, a body of abrasive material having a plurality of radially extending slots in the usable portion thereof, the slots being arranged in two or more series, the adjacent edges of the respective series of slots being located in substantially the same plane whereby only one series of slots will be open to the front face at any time throughout the Wear of the disk to produce a uniform cutting action, and reenforcingmeans in the rear part of the disk rigidly tying all sections of the disk together.

3. A grinding disk of the character described comprising, in combination, a front layer having two series of slots with the slots in one series arranged in staggered relation to the slots in the other series, the rear plane of the front series being substantially coincident with the front plane of the other series whereby only one series of slots is open to the grinding face of the disk at any time throughout the wear thereof, and a rear layer provided with reenforcing means for uniformly distributing the stresses on the disk throughout the area thereof.

4. A grinding disk of the character described comprising, in combination, a plurality of segments adapted to be secured to a supporting wheel to form a complete disk of annular form, each segment having one or more radial slots extending from the inner periphery to the outer periphery and one or more radial slots in alternate relation to the first-mentioned slots extending from the outer periphery but terminating short of the inner periphery, the slots having a depth substantially equal to the usable portion of the disk, and reenforcing means and anchoring devices located in the rear portion of each segment.

INGLE R. SHUE.

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