US2440686A - Laminated abrasive wheel - Google Patents

Description

May 4, 1948' AE. HURsT l LAMINATED BRASIVE WHEEL Filed March 33;, 1945 2 Sheets-Sheet 1 .5 ZZ Z5 17' 73 Z 78 May 4, 1948. E mms-rv 2,440,686

LAMINATED ABRAS IVE WHEEL Filed March 3l, 1945 2 Sheetsfsheet 2 `'afwara Hursi l Patented May 4, 194s UNITED s'rA'rEs Pivrsrrrl oFFlc LAMINATED ABRASE WHEEL Edward Hurst, West Newton. Mau., asslgnor to United Cotton Products Company, Mass., a corporation of Massaohule Fall River, tts

`Application March 31, 1945, Serial No. 585,860

This invention relates to the manufacture of abrasive wheels. More particularly, it relates to abrasive wheels of the type consisting of a rotatable hub and av detachable annular rim, the latter being provided with an abrading or polishing surface. It also pertains to the method of maksive-coated periphery is rigid and inflexible it is customary to pound the periphery of the wheel with a blunt instrument to fracture the abrasiveglue coating. The ygrinding and polishing surfaces of wheels so made are at best lacking in uniformity, and harsh and irregular in their cutting action, since they depend almost entirely upon the background or body of the wheel for whatever resilience or softness theyl possess. and if suilicient adhesive and abrasive is applied to the surface to give the wheels any satisfactory degree of durability the resilience of the wheel body is so far removed from the grinding surface as to lose a greater part of its cushioning eil'ect upon the work beihg surfaced. Moreover, setup wheels of the prior art have an unsatisfactorily short life, requiring a renewal of the grindin g surfaces after a use of only a few minutes, or a matter of a few hours at most, depending upon the operation being performed and the type and amount of abrasive coating on the wheel. The action of the wheel during its useful life varies from a reasonably acceptable performance by the freshly prepared surface to a point where the cutting action is so ineffective that the surface must be renewed. The application of glue and abrasive to the surface is furthermore a messy and unpleasant job and its elimination would be a distinct advantage for the latter reason alone.

It is an object of the present invention to provide an abrasive wheel for fine grinding and finishing operations which will be highly satisfactory in use and also will avoid the disadvantages set forth above. It is a further object to provide such a wheel which will have an exceptionally long life as compared with abrasive wheels heretofore employed for similar uses and which will provide satisfactory cutting action throughout its useful life. A stili further object is the '7 claims. (ci. 51-193) provision of a wheel of the herein-described type in which the abrading member -of the wheel can be facilely replaced after a satisfactory long and economical life. Further advantages of the present product include improved resilience and smooth operational qualities vof the wheel throughout its useful life and an ability to retain its smooth. cool and free cutting nature by reason of its habit of self-dressing during grinding operations.

In accordance with the present invention an abrasive wheel for fine grinding and finishing is made with a rotatable hub member and a detachable annular rim member, the latter being provided with an annular side grinding or peripheral grinding surface of abrasive material. The wheel of the present invention is further characterized in that the abrasive material constituting the annular or peripheral grinding surface of the wheel is composed of a large number of' individual abrading members suitably secured upon and engaged by the `detachable annular rim and consisting of a fabric-reinforced felted fibrous abrasive-included sheet material.4 Other details and features of the present invention will become apparent as the description proceeds.

In order to more clearly understand the nature of the present invention, reference is made to the drawings in which:

Figure 1 is a plan view of one face of a fragmentary portion of a fabric-reinforced felted fibrous abrasive-included strip material employed in the process of forming the reinforced abrasive strip material embodied in the present invention;

Figure 2 isa like view of the the strip material shown in Figure 1;

Figure 3 is an exaggerated vertical cross section'through the line l-S in Figure 1;

Figure 4 is a plan view of the fabric-reinforced abrasive 'strip material of Figures 1, 2, 'and 3 after it has been doubled back upon itself with a metal bar strengthening element included in the base portion of the U-shaped strip material and die struck to mark olf designated short lengths of A the strip prior to cutting into abrasive segments;

Figure 5 is an exaggerated vertical cross-section through the line 8 5 in Figure 4: Figure 6 is aplan view of one of thel notched abrading elements obtained by cutting segments from the strip material of Figures 4 and 5;

Figure 'I is a plan view of a modiedform of notched abrading element made according to the present invention;

Figure 8 is an exaggerated vertical cross-section through the line l-l in Figure '7:

opposite faceof tents, and which vfabric' run perpendicular thereto.

Figure 9 Ais afragmentary plan view of an abrasive wheel embodying the present invention and having a pheripheral grinding surface composed of the abrasive elements shown in Figure 6;

Figure lois an expanded cross-section through the'line ill-I0 of Figure 9;'.,...

Figure 11 is a plan view of an abrasive wheel embodying the present invention and'having an annular side grinding surface composed of the. abrasive elements shown. in Figure 6; and

Figure 12 is a section taken along the line I2-I2 of Figure 11.

The abrasive character of the wheels of the present invention is imparted by the abrasiveincluded felted fibrous sheet material, such as for example, that described more fully in my Patents Nos. 2,284,738 and 2,284,739. Briefly, the abrasive sheet material defined in the aforesaid pat- I have found to be satisfactory present wheelsis composed of a plurality of carded fibrous membranes which have been superimposed one on the other and the fibers intertwined to form when compacted a for making the strong, substantially non-lamellar brous'web.

During the process of forming the fibrous web material abrasive grain of the desired particle size, and adhesive binder, are incorporated internally of the web to form a sheet material which is abrasive in character throughout its thickness. For further details of such abrasive sheet material and methods of making it, reference is made to my above-mentioned patents.

Referring further to the drawings, Figures 1,

2 and 3 are various views of a fragment of abrasive strip material such as is formed in the process of making lthe abrading elements constituting the grinding surface of wheels of the type herein described. A long strip of woven fabric Ill serves as a reinforcing base or core for the abrasive strip material to be formed, the weight of the fabric chosen being dependent upon the character and size of the abrasive particles embodied in the felted abrasive strip attached, the number of layers of abrasive material to be applied to the core and the particular use for which the wheel is being made. It is important for most satisfactory results that the warp threads I I of the reinforcing fabric run lengthwise of the strip and the weft or filling threads I2 of the As will be apparent as the description proceeds, such a disposition of the warp and weft threads will result in the warp threads being disposed parallel to the axis of rotationl and the weft or filling threads will be disposed radially of the wheel. A woven fabric which has been found highly suitable is a cotton drill cloth having ,a thread count of 124 x 60, the warp thread count being given first.

A number of strips of abrasive included felted fibrous sheetl material of different. widths are then adhesively attached to both faces of the reinforced fabric core. As shown in Figures 1, 2, and 3, two narrow strips I3 and I4 are attached by means of adhesive I5 to one face of the fabric I with the outer edges even with and following the outer edges of the fabric so that the fabric has a clear area IB centered laterally and extending lengthwise of the strip. On the other face of the fabric core I0, two broad strips I'I and I8 of the abrasive-containing felted fibrous material, which in total width are almost equal to the width of the fabric strip i0, are secured thereto by adhesive I5, after which narrower strips I9 and 20 are adhesivly secured by `adhehesive I5 to the strips of abrasive-included fibrous material Il and I8 previously adhered to the fabric strip i0. Casein has been found highly satisfactory as the adhesive for securing the various elements of the reinforced strip together.

Other adhesives which can be used include high grade animal glue, particularly when hardened with formaldehyde, and adhesives. such as phenolic and urea resin adhesives and the like. All the strips of abrasive-included fibrous sheet material are co-extensive in length with the length of the fabric reinforcing strip,

After a composite strip of abrasive material such as that shown in Figures l-3, inclusive has been formed, the strip is bent or folded back upon itself midway between its side edges and lengthwise of the strip so that the fabric and its adherent abrasive-included fibrous sheet material form a U-shaped element with an additional coating of adhesive I5 holding the thusly pressed strip in that position. At the time of folding and pressing -the strip material to U-shape a ribbon or\ bar 2| of metal or similar rigid material co-extensive in length with the strip of fabric I0 .and approximately equal in thickness or gauge to the combined thickness of layers I3 and I4 attached to the inner sides of the fabric I0 and of a width approximately equal to one half the width of the clearance space I6 left on the side of the fabric shown in Figure 1 between abrasive strips I3 and I4 is inserted in the base of the U-shaped strip. The bar 2I 'serves to stiffen and strengthen the abrading elements to be cut from the strip material.

The abrasive strip is further subjected to pressure with special dies to mark such designated segments 22 separated by narrow grooves 23 and circular depressions 24 extending inwardly from the outer edge of the strip material to the bar or ribbon 2i. The strip in its folded form as thus stamped, as shown in Figures 4 and 5, is then separated along the grooves 23 and by severance of the metal bar adjacent the circular depressions to provide a number of individual abrading elements 25 such as that shown in Figure 6.

Notches 26 are usually cut inA each side of the unit 25 for engagement with the annular rim in making the abrasive wheel embodying those units. Each of the notches is so located that the lower portion 21 cuts into the tcp edge of the metal ribbon 2|.

Figures '7 and 8 depict by plan and vertical cross-sectional views, respectively, a modified form of segmental abrading element made similarly to the element shown in Figures 5 and 6 but. differing in that the longer felted abrasive strips I1 and I8 of Figures 5 and 6 have been omitted and the lower edges of the shorterflbrous abrasive strips I3, I4, i9 and 20 do not extend downwardly all the way to the upper edge of the rigid reinforcing element 2 I.

Figures 9 and 10 depict by fragmentary plan and expanded cross-sectional views, respectively, an abrasive wheel for finish grinding and polishing embodying the present invention, and in which the periphery of the wheel constitutes the grinding surface. In making such a wheel a plurality of individual abrading members 25 are assembled face to face on a metal support which is bent to form an annular rim 28, the sides129 of the metal support being turned upwardly and the ends 30 thereof crimped or otherwise deflected inwardly so as to engage the notches 26 in the side of the abrasive members 25 to tightly and firmly grip and hold the members in place. A

spindle 42 by bolts 43 and u when parallel to the abrading i and easily strips out exposing the soft ends of the low-twist filling threads. The lling threads are suliicient number of the abrading elements are contained in the channel shaped annular rim to lill the rim and provide a substantially continuous circumferential abrasive surface 3|. It is to be observed that by the use of strips of felted fibrous abrasive material of different widths that each of the individual abradingmembers is somewhat tapered by successive stages from the base outwardly whereby the members when assembled to form a peripheral grinding surface tend to lit more closely together over their entire area. The annular rim containing the abrasive material is mounted upon a rotatable hub member comprising two side plates 32 having inwardly projecting hubs 33 constituting an integral part of said side plates, The plates 32 are provided with jaw portions 34 which between them fit about and securely hold the annular rim loaded with abrasive material in position. The hub portions 33 are adapted to be mounted on a suitable spindle 35 and held in place by nuts 36 and washers 31.

Figures 11 and 12 are plan and diametrical cross-sectional views of a modified form of abrasive wheel embodying the present invention and adapted for side grinding operation with an annular abrasive surface 38. The supporting annular rim 39, loaded with abrading units 25, which are engaged by the inwardly deiiected sides 40 of the annular rim, is bent in such a way that the abrading elements when mounted project laterally from the Wheel to provide an effective annular grinding face instead of the peripheral grinding face provided by the wheel of Figures 7 and 8. The abrading members 25 are preferably modified from the type shown in Figure 6 in that they are4 not provided with the same inward taper obtained by using abrasive strips of different widths but are substantially the same thickness from the top to the bottom by reason of having the outer layers I9 and 20 of abrasive-included material substantially co-extensive with layers Il and I8, One or more wedge shaped pieces may be used, if desired, to provide for the slight difference between the inner and outer circumferences of the annular surface.

The rim 39 loaded with abrasive material is rigidly and strongly secured to a rotatable hub member comprising a base plate 4I fastened to a suitable provided with an annular detachable flange 44 attached to the base plate 4l at the periphery by bolts 43 and having the upper edge 46 'turned inwardly to engage the annular rim 39. The rim 33 is further secured by radially slidable curved engaging plates 41 which are bolted to the bed plate 4| by means of bolts 48 and when fastened in position clamped tightly against the inner side of the rim to force it against the flange and hold the position.

It is highly desirable, and most satisfactory grinding action is obtained, when the warp threads of the reinforcing fabric core of the individual abrading members lie in a lengthwise direction substantially parallel to thejoperating abrasive surface of the wheel with the lling threads consequently lying substantially perpendicular to the abrading surface of the wheel. Such a disposition of the threads provides a means of continuously renewing the abrasive surface without requiring a separate dressing lof the wheel. When a. warp thread becomes exposed surface it quickly usually made from soft-twist yarns which untwist abrasive -rim firmly in However, the disposition of the l 6 y or ravel very easily so that the lling thread ends wear away and again expose another warp thread, thereby repeating the self-dressing action.

If it is desired to renew or dress the abrading surface oi' the wheel to a greater extent than it is dressed during the normal operation of the wheel, such renewal or increased dressing action can be readily accomplished by removing the wheel from the shaft and replacing it on the shaft with the side faces in reversed positions. As reversed. the edges of the individual abrasive segments, which were previously 1e ding edges as the segments made contact wi h the work being surfaced, become the trailing edges andthe abrading surface of each segment is given an augmented dressing action over and above that which it receives during continual operation of the wheel. threads is such that it is not essential that the wheel be reversed under ordinary usage.

The filling threads never extend excessively beyond the abrasive surface in such a way as to mask the cuttingaction of the abrasive due to the tendency of the wheel in action to pinch any extending fibers between the abrasive particles of the grinding surface and the work being ground and sever them, Consequently there is provided in abrasive wheels so core which serves to materially strengthen the resulting abrasive wheel and preserve the ability of the wheel to stand up to the work being surf. faced without undergoing a ragged, excessive or premature destruction of the surface. At the same time the cutting action of the abrasive par-l ticles is in no way interfered with by the presence at the surface of an excessive'amount of nonabrasive material.

Another advantageous feature of the presently constructed wheels is the added opportunity which such a construction aiords to obtain resiliency in abrasive action with an exceedingly wide range of gra-de hardness of the abrasive material constituting the abrasive element of such wheels. It is evident from a consideration of the abrasive device of the multiple segment type construction herein disclosed that the individual segments making up the abrasive surface are each free to move relative to each other as contact with the work is made so that an appreciable amount of motion and resilience is: ob tained over that ordinarily obtained as a result of the material resiliency inherent in the abrasive included felted fibrous sheet material itself embodied in the wheel. The density, and consequently the hardness grade, of each abrasive segment can be increased or decreasedby raising or lowering the amount of pressure employed in compacting the fibrous abrasive-containing material onto the fabric reinforcing core.

Having described and set forth the invention in detail it is desired to claim:

l. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deflected inwardly and a plurality of abrasive members positioned in made a fabric reinforcingmember extending accesso 2. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deflected inwardly and a plurality of slab-shaped abrasive members disposedi parallel to the axis of said rotating hub member and extending radially from and circumferentially lling said annular rim to constitutea peripheral abrading surface, each of said abrasive members comprising several layers of abrasive-included felted fibrous sheet material 'adhesively secured to a woven fabric reinforcing element, each of said abrasive elements beine strengthened by an internally secured rigid bar member extending transversely/ across' the base portion of said abrasive element, said abrasive elements having lateral recessed portions engaged by the inwardly deflected portions of the sides of said annular rim.

3. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deflected inwardly and a plurality of slab-shaped abrasive members disposed parallel to the axis of said rotating hub included felted brous sheet material of different widths adhesively secured to the sides of the woven fabric reinforcing element and extending inwardly from the upper edge thereof. each of said abrasive members being stlffened by a transversely disposed rigid bar element secured within and at the base of said U-shaped fabric reinforcing element. said abrasive members having lateral recesses engaged by the inwardly deected sides of said annular rim.

6. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides de'iiected inwardly and a plurality of slab-shaped abrasive members positioned tranf'ersely in and circumferentially filling said annular rim, each of said abrasive members comprising a U-shaped woven reinforcing element so disposedl that the warp threads thereof lie parallel to the axis of rotation of said wheel and the weft or filling threads thereof lie radially of the wheel, a plurality member and radially disposed in sufficient number to circumferentially fill said channel shaped annular rim and projecting laterally therefrom to provide an annualr abrading surface, each of said abrasive members comprising several layers of abrasive-included felted fibrous sheet material adhesively secured to a woven fabric reinforcing element,l each of said abrasive elements being strengthenedby an internally secured rigid bar transversely across the base portion of said abrasive element, said abrasive elements having lateral recessed portions engaged by the inwardly deflected portions of the sides of said annular rim.

4. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deflected inwardly and a plurality of slab-shaped 'abrasive members positioned in and circumferentially filling said annular rim, each of said abrasive members comprising a U-shaped woven fabric reinforing element having a plurality of layers of abrasiveincluded felted fibrous sheet material adhesively secured to the sides of the woven fabric reinforcing element and stiffened by. a transversely disposed rigid bar element secured within and at the base of said U-shaped fabric reinforcing element, said abrasive members having lateral recesses engaged by the inwardly deflected sides oi said annular rim.

5. An abrasive wheel comprising a rotatable hub member and a. detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deflected inwardly and a plurality of slab-shaped abrasive members positioned in and circumferentially filling said annular rim, each of said abrasive members comprising a U-shaped woven fabric reinforcing element having a plurality of layers of abrasiveof layers of vabrasive-included, felted fibrous sheet material adhesively secured to the faces of the woven fabric reinforcing element and extending inwardly from the peripheral edge of said reinforcing element over the greater part of said fabric reinforcing element, and a rigid strengthening element secured within and at the base of said U-shaped fabric, said abrasive member having lateral recesses engaged by the inwardly deflected sides of said annular rim.

7. An abrasive wheel comprising a rotatable hub member and a detachable annular member attached thereto, said annular member comprising a channel shaped annular rim having at least a part of the sides deected inwardly and a lplurality of .abrasive members positioned in and thereof lie' parallel to the axis of rotation of said wheel and the weft or filling threads thereof lie radially of the wheel, each of said abrasive members being strengthened by an internally secured rigid bar member extending transversely across the base portion of said 'abrasive element, said abrasive members having lateral recessed portions engaged by the inwardly deflected portions of the sides of said annular rim. f f

EDWARD HURST.

REFERENCES CITED The following references are of record in the file of. this patent:

UNITED STATES PATENTS v Number Name Y Date 299,311 Abbott May 27, 1884 310,799 Compton Jan. 13, 1885 455,277 Cummins June 30, 1891 596,014 Condon et al.- Dec. 2l", 1897 603,259 ComptOn May 3, 1893 FOREIGN PATENTS Number Country v Date 196,084 Great Britain Apr. 16, 1923

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