June 9, 1964 J. ROBERTson, JR 3,136,100. GRINDING WHEEL Filed July ill, Sas/S SSES. W WS s INVENTOR. 7o A/n Robee 56& Je. BY.

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1 June 9, 1964 J. ROBERTson, JR GRINDING WHEEL Filed July ill, 1962 &s W WS s Sas/S SSES INVENTOR. 7o A/n Robee 6& Je. BY.3% /, 177 or mey

2 United States Patent Office Patented June 9, 1964 GRINDING WHEEL John Robertson, Jr., Princeton, Mass, assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Filed July 11, 1962, Ser. No. 9,169 Claims. (CI. 1-9) This invention relates to a grinding wheel and a per manently affixed mounting means for the same which is so simple and which can be made so inexpensively that it can be discarded with the stub of the wheel after the latter has worn down so that it is no longer useful. The throw-away mounting means is assembled with a grinding wheel hav ing a depressed center and is made of two parts, namely, a threaded element which is fitted through from the front or working face side of the wheel to extend rearwardly through the center hole thereof and a rear flanged hub portion adapted to be mounted on the extended portion of the threaded element and centered on the rear side of the wheel. Illustrative of the cheapness with which the construction may be made, it consists of only two parts which may be produced by die casting. It is of fundamental importance that the rear member has an outer annular flange adapted to be placed in firm contact with the back side of the wheel and give it a solid support, and the rear flange of this rear member is so shaped that the aforesaid depres sion formed centrally in it will always be deeper than the recessed center formed in the wheel. In this manner, regardless of the tolerance permitted in the manufactur ing of the wheel, there will always remain a space between the inside face of the rear member and the wheel surface when the outer flange is in contact with the rear face of the wheel and the depressed central portion of the wheel is disposed in the central depression of the rear member. This space, which exists within the confined portion be tween the depressed rear flange of the rear member and the depressed portion of the wheel, is then filled with a suitable adhesive, preferably a resin, which solidifies to adhere and hold the parts in the desired assembled rela tion. In actual practice, it has been observed that the adhesive or resin filler provided as above described not only serves to adhere the rear flange element assembled to the wheel, but when such resin or adhesive becomes solidified, it serves as a solid spacer. The spacer is automatically ad justed to fit between the wheel and the rear member so that when a front threaded element or nut is screwed tight ly onto the driving spindle, the wheel is held firmly en gaged between the rear member and the nut element. The ability to accommodate the maximum tolerance in wheel production within the central depression of the rear mem. ber or hub is an important feature of the invention and contributes greatly to the successful manufacture and use of a relatively inexpensive wheel and mounting means therefor. - In brief, the present invention comprehends a most ef ficient back pad or supporting mount for reinforced, pref erably organic bonded, recessed hub wheels by the use of a novel cushioning material in combination with the back pad, the wheel and the cooperating attaching means. The cushioning material, i.e., the bedding adhesive or resin, as sures a support of the proper rigidity with exact and com plete uniformity of contact area between the wheel itself and the mount. The result is a more efficient stress dis tribution and, in turn, a stronger product or a product of at least equal strength with conventional combinations, but with less bulk and at an appreciably lower cost. The mounting of this invention, as explained above, also elim inates the effect of dimensional variations which are com t mon to wheels of this type. It is a particular feature of the invention that the cushioning material, notably, the ad hesive or resin, will take the form of the depression defined by the wheel and the back pad or rear member. Hereto fore recessed hub wheels employed two types of supports, namely, a flexible type and a rigid type. The flexible type had a band of material formed as the lands of the wheel mount which because of its flexibility would give under pressure. This would allow the wheel to fit without caus ing any major stresses occasioned by the tightening of the mounting. It had the disadvantage of deflecting under grinding stresses and, therefore, never fully supported the wheel. The second type or rigid support overcame this disadvantage. However, it offered a further disadvantage of its own because stresses, even to the extent of cracking the wheel, would sometimes occur in the wheel due to tightening of the front threaded member or nut. This cracking under stress was caused by the variation in the dimensions of both the rigid bodies, namely, the rear and front members of the mounting, which seldom matched precisely. I have discovered that if a pad or rear member is designed to insure wheel and land contact in every case, the depth of the recess in the rear member must be as deep as the production tolerance allowed for the depth of the most extreme wheel recess. However, in making use of such a structure, unless all aspects of my invention are used, a wheel with a shallower central recess will have more or less additional stresses added to it by the threaded front element or nut when the same is screwed home, thereby forcing the wall of the recess in the wheel to be in contact with the pad or rear element which may be spaced somewhat from the back side of the wheel when any tolerance other than the maximum production toler ance is encountered in a wheel. The present invention eliminates the disadvantages of both of the conventional mountings above described while maintaining their advantages. This is accomplished by supplying an economical cushion, i.e., bedding, as the ad hesive or resin, which conforms in shape to both the cen tral recess in the pad and the wheel and, at the same time, is sufficiently rigid to support the wheel in grinding. The adhesive or resin constituting the bedding or cushion pref erably flows under heat or pressure or both and fills the space between the inside or front wall of the recess in the pad and the outside or back wall of the recess in the wheel, conforming to both, and then hardens to form an adhesive cushion of the required rigidity to hold the members in fixed position. In this connection, conventional epoxy and polyester resins, filled and unfilled, have proven suc cessful, but any number of resins or adhesives may be used and are available on the market. A specific formulation and process which has been most successful economically and technically is detailed below. Formulation of adhesive or cushioning material: Material Source Parts by Weight Polyester resin No. 109 with Cobalt Naph- Naugatuck. OO thenate. Talc Methyl Ethyl Ketone Peroxide Cadet Thin depressed center resinoid bonded wheels provided with mountings in accordance with this invention were compared with similar wheels with heretofore known com mercial mountings on the high speed rotary side pressure test and in every instance wheels mounted in the manner I teach proved entirely satisfactory and efficient, i.e., the mounting means performed effectively until the wheel was worn down, at which point both the wheel and mounting could be economically discarded.

3 3 It is an object of the invention, therefore, to provide a construction which does not depend solely on the strength. of the material of the mounting and the adhesive connec tion for driving the grinding wheel. Another object of the invention is to provide a struc ture in which it is possible to properly support the wheel, especially when pressure is applied near its periphery, which causes it to flex. This continued pressure and flex ing encountered in use of conventional mountings often results in weakening such known mountings and thereby produces a failure of the adhesive or loosening of the mold ed mounting. It is additionally an object of the invention to provide preattached and properly aligned mounting attached to a grinding wheel as a unit. Also, it is an object of the invention to provide a grind ing wheel with a self-aligning mounting which may be coupled to a drive means to apply pressure between ele ments of the mounting to properly clamp, support and drive the grinding wheel therebetween. Furthermore, an object of the invention is to provide a continuous bearing surface between the mounting and the grinding wheel to assure a uniform stress distribution. Still another object is to provide an adhesive-type hard enable bedding material between the mounting and the grinding wheel which sets up to assist in permanently holding the mounting attached to the grinding wheel. An important object of this invention is to provide a mounting which will accommodate the most extreme toler ance permitted in the manufacture of the depressed center or hub portion of the known depressed center type of grinding wheel. Again, it is an object of this invention to provide a mounting having a continuous annular mating land adja cent its periphery for contacting and rigidly supporting the grinding wheel from the back side throughout an area located beyond the depressed hub portion of the wheel and beyond the periphery of the elements of the mounting means which form the wheel clamping portion thereof. Essentially the invention comprises a mounting for de pressed center grinding wheels having two different op posed supporting members each of which is provided with a circular flange. One of the flanged pieces has an axially extending hub extension which is internally threaded and whose external diameter is of a size to neatly fit the hole in the center of the grinding wheel. The extension is adapted to be inserted into the hole from the front side of the wheel and is of a length to project beyond the rear surface of the hub of the grinding wheel. A flange formed integral with this member is fixedly attached to the front side of the wheel within the recess formed by the depressed center with an adhesive that solidifies in place. Onto the rearwardly projecting portion of the extension is fitted a larger annular flange or supporting member. which is axially aligned thereon. The rear supporting member has a depressed configuration which is deeper than the deviation in the rear wall of the depressed con figuration of the hub portion of the grinding wheel. The inside diameter of the annular portion of the rear support member is larger than the diameter of the depression of the hub. Both the depth of the depressed configuration of the inside of the rear support member and the inside diameter of the depression are larger than the maximum variation allowed in the manufacturing tolerances, to al ways provide a void between the rear wall of the wheel and the front wall of the depressed portion of the rear Supporting member which void may be filled with an ad hesive of a type which hardens to a rigid condition. The periphery of the rear supporting member is finished to have a flat circular land or surface which contacts the surface on the back side of the wheel beyond the periphery of the depressed hub. - The rear supporting member has a bearing shoulder surrounding an aperture through which the shouldered shaft of the driving means passes. Such a construction is 4. provided so that the shoulder of the shaft contacts the bearing shoulder of the supporting member when the front flanged member is screwed onto a threaded extension of the shaft thereby applying a clamping pressure to the grind ing wheel between the front and rear supporting elements. In the accompanying drawings is shown the preferred embodiment of the invention in which, FIG. 1 is a rear plan view of the grinding wheel and attached mounting. 10 FIG. 2 is a side elevation exploded to show the main components before attachment to one another, and FIG. 3 is a vertical section taken on line 3-3 of FIG URE 1 showing the mounting attached to the depressed center grinding wheel. Referring to the drawings, a grinding wheel 10 has a central depressed center or hub portion generally denoted A2 comprising a surface 14 on the front of the wheel and an opposite surface 16 of similar shape on the back side which is substantially parallel to surface 14. The grind ing portion of the wheel extends laterally from the hub and has a front face 8 and rear face. As shown the surfaces 14, 16, 18 and all lie in planes which are par allel to each other but it is obvious that the grinding por tion can be cupped or have any other conventional shape The wheel has a central hole or aperture 22 of predeter mined size which is disposed centrally in the depressed center or hub portion 2, the wall of the aperture being disposed at substantially right angles to the surfaces 4 and 16. A mounting assembly is provided for supporting and driving the grinding wheel. The mounting consists of an internally threaded member 23 having a cylindrical portion 24 extending from and integral with a flange 26. The flange has a thickness that is less than the depth of the recess or depression forming the hub in the grinding wheel. The cylindrical portion 24 of member 23 has an external surface 28 which closely fits the aperture 22 in the hub portion of the grinding wheel and extends through the hole to project beyond the surface of rear Wall 16 of the depressed hub. Cooperating with member 23 is a rear supporting mem ber having an aperture 32 for engaging on the extending cylindrical portion of member 23. The supporting mem ber has an enlarged depressed shape similar to the shape of the depressed hub, but deeper and of larger diam eter than the shape of the rear wall 16 of the depressed hub over which it fits. The rear support member has a wall 34 connecting its central portion with a peripheral flange 36 which contacts the rear surface of the wheel beyond the periphery of the depressed hub portion 12. The rear Support member is formed with a recess or depressed portion enclosed within wall 34 which is of a depth greater than the distance between wall and the plane of wall 16 which is the depth of the depression of the hub portion 12 of the wheel as measured between surfaces 16 and thus leaving a space or void between the front or inside surface of wall 34 and the rear wall 16 of the wheel when the rear support member is fitted onto the wheel. Concentric with the aperture 32 is another surface 40 in the member which is provided for a purpose that will appear more fully below. On the supporting mem ber is a shaped portion to accommodate a wrench for removing the mounting assembly 24 relative to the threaded drive shaft 48. In practice, it has been found that due to variations in contour between grinding wheels and of mountings manu factured separately, it is practically impossible to match or make complete contact between their surfaces to pro vide a good bearing support. Therefore, the invention avoids this difficulty by providing, as stated before, a recess surface of sufficient depth to always provide a void between surface 16 and wall 34, which void is adapted to be filled with the bedding material 38, which is

4 3,186,100 6 of such a nature as to conform to the shape of both wheel unit, resulting in savings of time and consequently the grinding wheel and mounting as the rear support of labor costs in mounting a new wheel. member is fitted onto the wheel during the manufacturing There has thus been provided by this invention an assembly operation. economically-produced grinding unit with pre-attached Additional material 38 is also located between the front drive means, which has many practical advantages in that surface 14 and flange 26. It provides a continuous, per it provides good support and inherently compensates for dimensional variations encountered in the normal manu manent bearing surface and has sufficient adhesive quali ties which prevent the mounting assembly 23- from facture of reinforced grinding wheels of the depressed being removed once it has been attached to the grinding center type. Such a mounting also maintains the same wheel. The material 38 is semi-fluid or at least plastic O uniform support throughout the life of the grinding initially but hardens once the parts 23 and are fitted wheel, utilizes an improved application of clamping stress onto the wheel. In this way a completely uniform Sup es more uniformly. This construction additionally pre port is established and maintained throughout the life of vents fracturing of the grinding wheel by eliminating the grinding wheel and yet this means provides for quick distortion of the wheel during mounting and the entire ly attaching or detaching the wheel from its drive means. wheel assembly is therefore safer to use. It further it will be seen that very little if any of the adhesive-type minimizes the wasteful down time necessarily encoun bedding material 38 is present between the continuous tered during wheel changes when replacing a worn-out land or surface 36 of the supporting member and unit. the surface so that this structure provides for direct It has been suggested above that wheels of different contact and support of the wheel without permitting any shapes other than the planar configuration here shown, bending or distortion of the grinding wheel by the mount may be fitted with the hub assembly of this invention to advantage. It is suggested that many other and different any different types of materials may be used to attach modifications may be made of the preferred and described embodiment of the invention and it is to be understood the mounting assembly 23- to the grinding Wheel which will set up sufficiently to properly Support it. that all matters hereinbefore set forth or shown in the Such material may be filled or unfilled epoxy or polyester accompanying drawings are to be interpreted as illus resins, as above described. An example of a most Success trative only and not in a limiting sense. ful material contains 100 parts by weight of polyester I claim: resin with cobalt naphthalene, 100 parts by Weight of 1. An abrading tool for mounting on a rotatable shaft talc and 1. parts by weight of methyl ethyl ketone perox having a reduced threaded end portion and shoulder ide. This material will initially be a paste at room tem thereon comprising, a grinding wheel with a depressed perature. It is applied to both surfaces 14 and 16 of center, said depressed center having a central raised sur hub portion 12 in a bead of proper size required for each face of predetermined height above its back side, a de of the front and rear flanges 26 and 34 respectively. pressed surface opposite said raised surface on its front side and a centrally disposed aperture therein, a flanged The nut 23 is then inserted in the aperture 22 from the front side of the grinding wheel and the Supporting mem member having an internally threaded portion extend ing through said grinding wheel and beyond said raised ber is placed over the extension of the nut 23, which automatically aligns the mounting assembly. Thereafter, surface, a supporting member centered on and by the portion of said flanged member extending beyond said the two are forced together under Sufficient pressure to 40 raised surface, a continuous land adjacent the periphery spread the material 38 until the land or annular surface of said supporting member contacting a portion of the 36 of the rear member makes complete contact with grinding wheel surface of said back side beyond the ex the adjacent surface of the wheel and the parts 23 and are maintained under slight pressure until the tremities of said raised surface, a recessed surface in the supporting member disposed relative to said land of a material 38 has set up. depth greater than the height of said raised surface, an After the material 38 has solidified it bonds parts 23 initially soft hardened adhesive-type bedding material and to the wheel and the preattached mounting and between said recessed surface and said raised surface and the grinding wheel or cutting tool can now be quickly between said flange member and said depressed surface attached onto a driving spindle as a unit by Screwing threaded member 23 onto the end 48 of the drive shaft. The surface 40 fits closely around the periphery of the shaft and as the part 23 is tightened on threads 48, part is driven home against shoulder 44 on the drive shaft. The final tightening can be completed by using a wrench on the squared-off portion of part for this purpose but the threads 48 normally coact with 23 to be self tightening when the wheel is driven. When properly mounted on the drive shaft the grinding wheel or cuting tool is positively clamped between the flange 26 and the central area of the wall 34 without depending solely on the adhesive qualities of the material 38 to hold it in driving relation. This prevents the mounting from shifting or loosening relative to the wheel during use and even if the adhesive connection fails, the wheel cannot break free of its mounting. While the wheel is firmly clamped at the center portion of the hub, it is apparent that the land 36 provides a somewhat flexible backup support for the rear of the wheel which engages the wheel beyond the periphery of the depressed hub portion and beyond the positively clamped area of the hub which is engaged between flange 26 and wall 34. Because the mounting can be produced cheaply and economically, as by die casting if desired, it may be thrown away with the worn-out grinding wheel or cutting tool and replaced quickly with another complete grinding 70 7 and means on the supporting member for supporting en gagement with said rotatable shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member. 2. An abrading tool for mounting on a rotatable shaft having a reduced threaded end portion and shoulder thereon, comprising, a grinding wheel with a central de side, a central depressed surface opposite said raised sur face on its front side, and a centrally disposed aperture thereon, an annular flanged member having an internally threaded portion in said aperture and extending beyond said raised surface, a supporting member axially aligned on and by the external surface of said flanged member ex tending beyond said raised surface, a continuous annu lar land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the diameter of said raised surface, a recessed surface in the supporting member disposed relative to said annular land of a depth greater than the height of said raised surface, an initially soft hardened adhesive-type bedding material between said recessed sur face and said raised surface and between said flanged member and said depressed surface and means on the Supporting member for supporting engagement with said

5 7 - rotatable shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member. 3. A unitized tool for mounting on a drive shaft having a reduced end portion with attaching means and a shoulder thereon comprising a cutting tool with a cen tral hub portion, said hub portion having a first shaped surface of predetermined height above its back side, a second shaped surface opposite said first shaped Sur face of a predetermined lesser height above its front side, and a centrally disposed aperture in said tool hub portion, a flanged member having a portion provided with means to engage said attaching means extending through said hub portion and beyond said first shaped surface, a Sup porting member axially aligned on and by the portion of said flanged member extending beyond said first shaped surface, a continuous surface adjacent the periphery of said supporting member contacting a portion of the cutting tool surface of said back side beyond the extremi ties of said first shaped surface, an elevated surface in the supporting member disposed relative to said continuous surface of a height greater than the height of said first shaped surface, an initially soft but ultimately hardened adhesive bedding material between said elevated surface and said first shaped surface, and between said flanged member and said second shaped surface, and means on the supporting member for supporting engagement with said drive shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member. 4. A drive mounting for a grinding wheel with a de side, a depressed surface opposite said raised surface on its front side and a centrally disposed aperture therein comprising a supporting member extending beyond said O 3. raised surface, a continuous land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the ex tremities of said raised surface, a recessed surface in the supporting member disposed relative to said land of a depth greater than the height of said raised surface, a flanged member for contact with the opposite side of said grinding wheel and an initially soft hardened adhesive type bedding material between said recessed surface and Said raised surface.. A drive mounting for a grinding wheel with a de side, a depressed surface opposite said raised surface on its front side and a centrally disposed aperture therein comprising a supporting member extending beyond said raised surface, a continuous land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the ex tremities of said raised surface, a recessed surface in the Supporting member disposed relative to said land of depth greater than the height of said raised surface, a flanged member for contact with the opposite side of said grinding wheel, mating means for axially aligning said supporting member on said flanged member and an initially soft hardened adhesive-type bedding material between said recessed surface and said raised surface and between said flanged member and said depressed surface. References Cited in the file of this patent UNITED STATES PATENTS 2,810,239 Burleigh Oct. 22, 197 2,823,496 Winter Feb. 18, 198 3,040,48 Tocci-Guilbert June, ,041,797 Mofily July 3, 1962