Abstract:
Grinding wheels are fabricated with outwardly extending circular peripheral rims having a continuous rim surface to which separate abrasive pieces, preferably of a super abrasive such as CBN, are secured by suitable adhesive. The superabrasive pieces are preferably circular and of a diameter corresponding to the width of the rim and are secured to the rim surface so as to either be adjacent and touch one another or to be spaced one from the other around the circle of the rim surface so that a predetermined amount but not all of the rim surface is covered with abrasive pieces. That rim surface coverage optimize grinding efficiency while providing space for fluid flow for purposes of cooling and carrying away particles from the grinding process.

Description:
BACKGROUND OF THE INVENTION-FIELD OF APPLICATION 
     This invention relates to grinding devices and methods of use of grinding devices; and more particularly to grinding devices constructed with a plurality of abrasive members and which employ such plurality of abrasive members in grinding processes. 
     BACKGROUND OF THE INVENTION-DESCRIPTION OF THE PRIOR ART 
     Some grinding devices are fabricated in the configuration of wheels or disks and employ the rim or cylindrical periphery of the wheel or disk in various grinding processes. Still other grinding devices, such as that shown in U.S. Pat. No. 2,089,040 employ the planar surface of the wheel or disk in various grinding processes, in fact, a pair of spaced and facing grinding devices are employed in the grinding processes of U.S. Pat. No. 2,089,040. 
     There are a considerable number of configurations for the grinding surfaces of grinding devices such as generally planar with a plurality of abrasive plugs embedded in the material of the wheel so that the exposed and utilized surfaces of the plugs are co-planar with the surrounding wheel surface as shown in U.S. Pat. No. 3,426,486; and generally curved and with spaced abrasive areas embedded in non-abrasive areas but so as to form a continuous curved surface as shown in U.S. Pat. No. 2,145,888. However, such continuous surface grinding devices are subject to the accumulation of “swarf” (the particles of grinding device material and material from the article being ground) between the grinding device and the article being ground, and the embedding of that “swarf” into the surface of the grinding device. This can reduce the efficiency of the grinding process; while movement of the “swarf” over the surface being ground can possibly scratch the surface of the articles being ground as well as otherwise hindering the grinding thereof. 
     Other grinding devices are constructed with: a plurality of bulges as shown in U.S. Pat. No. 2,262,583; a plurality of openings as shown in U.S. Pat. No. 3,041,799; and/or a plurality of spaced grinding rings separated by annular channels as shown in U.S. Pat. No. 2,201,410. However, even such grinding wheel constructions may be inadequate to efficiently remove coolant and other fluids and “swarf” from between the grinding device surface and surface being ground or to remove same quick enough. 
     Still other grinding devices utilize plural concentric grinding rings, each of different composition but concentrically mounted and in spaced relationship, with the respective grinding surfaces co-planar as shown in U.S. Pat. No. 2,309,016; while other grinding devices position plural spaced rings, each with different composition grinding surfaces, in planes that are angularly disposed one with respect to the other as shown in U.S. Pat. No. 2,451,295; and still other grinding devices utilize plural spaced grinding rings of different composition that have their grinding surfaces in different planes as shown in U.S. Pat. No. 2,673,425. However, here again, the spacings, if any, between the respective grinding rigs of these grinding devices may still prove insufficient to remove grinding fluids and “swarf” from the surface to be ground in an acceptable manner. 
     U.S. Pat. No. 4,456,500 shows and describes a grinding device in the form of a polisher wherein a plurality of teeth are formed from the base material of the polisher by a photoresist method. The resulting teeth, however, must be formed from the material of the grinding device base thus resulting in a possibly unwanted expense of forming the entire device of abrasive material which could be significant if it is desired to use a relatively expensive superabrasive as the abrasive material. U.S. Pat. No. 4,539,017 on the other hand forms the cylindrical peripheral surface of a grinding wheel with spaced islands of abrasive (in various configurations) molded by a centrifugal process to a foamed elastomer base to provide an elastic grinding element. The resulting grinding wheel because of the elastic base would appear to have limited application. In addition, centrifugal process for manufacture of these grinding devices would not be capable of producing a grinding device with similar abrasive islands disposed on a planar surface of a grinding device disk or wheel. 
     Arcuate and spaced grinding segments have been secured to a grinding device disk so as to provide an annular and planar grinding surfaces therefore as shown in U.S. Pat. No. 2,867,063. However, the grinding device disk construction for receiving those arcuate grinding segments requires spaced channels within which the arcuate grinding segments are secured by being bolted in place. The channel construction would appear to provide spaces within which unwanted “swarf” and other materials might collect thus possibly detrimentally affecting wheel operation and grinding efficiency. In addition, the wheel disk that carries the arcuate segments appears to be relatively complex and costly. 
     U.S. Pat. No. 2,629,975 shows circular blocks of abrading material embedded in arcuate segments that alternate about the same axis to form either a rough grinding device or a finish grinding device. The respective rough and finish grinding devices are utilized alternatively and not together. The patent provides no further detail concerning the size, spacing or thickness above the segment carrier surface for the abrading material or whether any part of such abrading material, in fact, is disposed above the surface of the arcuate members within which the cylindrical blocks of abrading material are embedded. The preparation of the carriers to receive the embedded abrasive blocks requires relatively costly expense and time as well as the time and expense to imbed the blocks in their respective carriers. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide new and novel grinding devices. 
     It is another object of this invention to provide new and novel combinations of grinding wheels or disks and grinding abrasives. 
     It is yet another object of this invention to provide new and novel processes for grinding articles of manufacture. 
     It is still another object of this invention to provide new and novel processes for more efficiently grinding articles such as brake rotors, power steering pump rings and rotors, valve plates and the like. 
     It is yet still another object of this invention to provide new and novel grinding wheels or disks which optimize the amount of abrasive to be utilized for grinding while at the same time also optimizing the arrangement of such abrasives to facilitate the flow of coolant and other fluids and the removal of “swarf” from the grinding area. 
     It is a further object of this invention to provide new and novel grinding wheels or disks which carry multiple abrasive pieces each of which is of optimum thickness and each of which provides an optimum abrasive surface for grinding. 
     Other objects and features of the inventions in their details of construction and arrangement of parts will be seen from the above and from the following description of the preferred embodiments when considered with the drawing and from the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawing: 
     FIG. 1 is a schematic, in perspective, of a grinding machine utilizing grinding wheels, incorporating the instant invention, for grinding articles of manufacture according to processes also incorporating the instant invention; 
     FIG. 2 is a plan view of a grinding wheel or disk, incorporating the instant invention, but only showing some of the abrasive pieces disposed thereon to better show details thereof; 
     FIG. 3 is a section view taken on line  3 — 3  of FIG. 2 with parts cut away to better show details thereof; 
     FIG. 4 is a schematic plan of the rim of the grinding wheel or disk of FIGS. 2 and 3 showing a layout of abrasive pieces thereon; 
     FIG. 5 is a plan view of one of the abrasive pieces utilized for the grinding wheel of FIGS. 2-4, enlarged to better show details thereof; 
     FIG. 6 is an end view of the abrasive piece of FIG. 5; 
     FIG. 7 is a plan view of an alternative grinding wheel, incorporating the instant invention, but only showing some of the abrasive pieces disposed thereon to better show details thereof; 
     FIG. 8 is a section view taken on line  8 — 8  of FIG. 7 with parts cut away to better show details thereof; 
     FIG. 9 is a schematic plan of the rim of the grinding wheel or disk of FIGS. 7 and 8 showing a layout of abrasive pieces thereon; 
     FIG. 10 is a vertical elevation section through an alternate abrasive piece and carrier, according to the instant invention, enlarged to better show details thereof; 
     FIG. 11 is a vertical elevation through the abrasive piece and carrier of FIG. 10 showing same disposed on a section of grinding wheel or disk according to the instant invention; 
     FIG. 12 is a plan view of a section of the grinding wheel or disk of FIGS. 2-4 enlarged to better show the disposition of the abrasive pieces thereon and the relative disposition of the abrasive pieces with respect to each other; 
     FIG. 13 is a plan view of a section of the grinding wheel or disk of FIGS. 7-9 enlarged to better show the disposition of the abrasive pieces thereon and the relative disposition of the abrasive pieces with respect to each other; and 
     FIG. 14 is a schematic showing an alternative abrasive piece configuration and an alternative arrangement plan for said abrasive pieces on a grinding wheel disk all according to the instant invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1 there is generally shown at  20  a schematic of a grinding machine incorporating a pair of grinding wheels  22 ,  24  carried by grinding wheel spindles  26 ,  28  which are, in turn, rotatively carried by workheads  32 ,  34  respectively. Workheads  32 ,  34  and spindles  22 ,  24  are shown disposed in a vertical spindle configuration (i.e. with their respective spindle axis of rotation in vertical co-linear alignment) but could also be disposed in a horizontal configuration (i.e. with their respective spindle axis of rotation in horizontal co-linear alignment). A first motor  40  serves to provide a rotative drive to spindle  26  and grinding wheel  22  through a drive belt  42  and pulley  44  arrangement; while a second motor  50  serves to provide a rotative drive to spindle  28  and grinding wheel  24  through a drive belt  52  and pulley  54  arrangement. Suitable and conventional power is provided for motors  40 ,  50  through suitable and conventional controls  60  carried by and/or within machine frame and base  62 . 
     Spindles  26 ,  28  and workheads  32 ,  34  are carried by machine frame and base  62  for movement towards and away from each other through controls  60  and otherwise in a conventional manner, and so as to provide for a spacing “S” between a work face  70  of grinding wheel or disk  22  and a work face  72  of grinding wheel or disk  24 . 
     An article carrier  90  is conventionally disposed for rotation about an axis  92  to move articles  94  to be ground through space “S” and between work face  70  of grinding wheel  22  and work face  72  of grinding wheel  24  all in substantially conventional manner. The spacing “S” of faces  70 ,  72  is set to permit entry therein to of article carrier  90  with articles  94  carried thereby and to facilitate grinding faces  100 ,  102  of articles  94  by movement of faces  70 ,  72  of grinding wheels  22 ,  24  towards and into contact with faces  100 ,  102  of articles  94 ; all in substantially conventional manner and under control of controls  60 . After each article  94  has had its faces  100 ,  102  ground the article exits space “S” from between grinding faces  70 ,  72 , is removed from article carrier  90  and is replaced by another article  94  with unground faces  100 ,  102  also in conventional manner. 
     The respective grinding faces  70 ,  72  of grinding wheels  22 ,  24  and the use of those faces and grinding wheels to grind articles comprise the instant invention. 
     Grinding wheels  22  and  24  are identical in construction and use and accordingly only grinding wheel  22  will be described in detail and with respect to FIGS. 2 and 3. 
     A grinding wheel base  120  (FIGS. 2 and 3) is provided for grinding wheels  22 ,  24 . Each base  120  is circular and disk-like and includes a peripheral rim  122  extending up from a face  124  of base  120 . A plurality of openings  130  (FIGS. 2 and 3) extend through base  120  to facilitate securing grinding wheel base  120  to grinding wheel spindle ( 22 ,  24 ) with a rear face  132  of base  120  disposed adjacent or proximate a corresponding surface or face (not shown) of the spindle. Additional openings  140  (FIG. 2) also extend through base  120  to facilitate securing base  120  to its spindle. 
     An annular surface  140  (FIG. 2) of rim  122  extends between concentric walls thereof and is configured and disposed to receive a plurality of abrasive pieces  150  which are secured in place by a suitable adhesive such as an epoxy or the like. While FIG. 2 only shows a few abrasive pieces  150  adhesively secured to surface  140  of rim  122  it should be understood that such abrasive pieces  150  are adhered to surface  140  in an array about the entire rim  122  as shown in FIG. 4; and that while FIG. 4 shows such abrasive pieces  150  slightly spaced one from the other that such abrasive pieces  150  may, in fact, be disposed so as to touch as shown in FIG. 2 or so as to be slightly spaced as shown in FIG.  4 . 
     Each abrasive piece  150  (FIGS. 2-6) is of circular disk-like or wafer configuration and is preferably fabricated from vitrified material with CBN cubic boron nitride or diamond to provide super abrasive abrasive pieces. Abrasive pieces  150  also be fabricated from formulations utilizing resin bond or metal bond and incorporating CBN or diamond. Other combinations of the aforementioned materials may also be utilized for abrasive pieces  150 . The diameter “D” (FIGS. 5 and 6) of each abrasive piece  150  preferably corresponds to the thickness “t” (FIG. 3) or width of rim  122 . An abrasive piece one inch (1″) in diameter has been found to function well but abrasive pieces in a range between one-half inch “½” to one and one-half inches (1½″) will also serve the purpose. Each abrasive piece is preferably fabricated to a thickness “T” (FIG. 6) of one-eighth of an inch (⅛″) but abrasive piece thickness between one-sixteenth of an inch ({fraction (1/16)}″) and one-half an inch (½″) would also function for the intended purpose. 
     In FIGS. 7 and 8 an alternative embodiment of grinding disk  220  is shown. Disk  220  is formed with an annular ring base  222  that includes an annular rim  224  about which abrasive pieces  230  are affixed preferably by a suitable adhesive such as that utilized for securing abrasive pieces  150  of FIGS. 2-6 to rim  122  (FIGS. 2-4) of disk  120 . Abrasive pieces or wafers  230  are preferably fabricated from the same materials as disks  150  and in similar size ranges of diameter and thickness; with the thickness of rim  224  substantially corresponding to the diameter of the abrasive pieces  230  that are to be affixed thereto. 
     Abrasive pieces  230  are applied to rim  224  of disk  220  about the entire rim as shown for pieces  150  and rim  122  of disk  120  and may be so applied in a spaced relationship as shown in FIG. 7 or closely adjacent each other as shown for pieces  150  in FIGS. 2 and 4. 
     A plurality of internally threaded openings  260  are formed in a rear face  262  (FIG. 8) of grinding disk  220  to facilitate securing a mounting plate (not shown) and grinding disk  220  together and to facilitate securing the so assembled grinding disk  220  and mounting plate to a grinding spindle such as spindles  22  or  24  (FIG.  1 ). 
     Another alternative grinding wheel construction is shown in FIGS. 9-11 wherein a grinding wheel base  320  which may be similar in construction to either base  120  of FIGS. 2 and 3 or base  220  of FIGS. 7 and 8 is provided with an annular rim  322  (FIGS. 9 and 11) having an annular surface  324 . A plurality of abrasive pieces  350  are disposed about surface  324  of rim  322 . Each such abrasive piece  350  is fabricated of similar materials and to similar dimensions as abrasive pieces  150  of FIGS. 2-6 or abrasive pieces  230  of FIGS. 7 and 8. 
     Each abrasive piece  350  is adhered to a surface  360  of a mounting piece  362  by a suitable adhesive such as that utilized to secure abrasive pieces  150  and  230  to their respective rims  122  and  224 . An internally threaded opening  370  extends into mounting pieces  326  to receive an externally threaded member (not shown), such as a bolt or the like, that extends through an opening  372 , formed through rim  322  of base  320 , to secure a mounting piece  363  and its abrasive piece or wafer  350  to grinding disk  320 . Mounting pieces  362  and abrasive pieces  350  may be so secured and disposed about rim  322  as shown in FIG. 9 or they may be otherwise spaced closer or further apart as will be hereinafter explained in greater detail. 
     Articles  94  to be ground may be items and parts such as brake rotors, power steering pump rings and rotors, valve plates or the like. Such articles  94  are fed between grinding wheels  22 ,  24  and the grinding wheels are rotated and advanced towards each other by specified amounts to grind off the correct amount of material from articles  94 . 
     The grinding process creates granular material both from the abrasive used for grinding and the article being ground. Preferably that granular material or “swarf” is carried away by fluids utilized for that purpose and which also serve to cool the articles being ground and the grinding wheels. 
     To effectively cool and to effectively carry away the swarf the fluid must circulate over and about the abrasive surfaces and over and about the articles to be ground. Thus, if the entire surface of the grinding wheel rims were covered with abrasive then it would greatly restrict the flow of coolant and articles would not be properly ground. In fact, heat generated during the grinding process could effectively destroy and render useless the articles being ground. Alternatively, too great a spacing between areas of abrasive of the rims of the respective grinding wheels or disks might result in inefficient grinding or improper grinding of the articles. 
     FIGS. 12 and 13 both show a pair of abrasive pieces  150  disposed one proximate the other on a portion of the surface  122  of rim  120  of grinding wheel  22 . Surface  122  has been divided into sectors  122   a ,  122   b  by dotted lines  123  and as such the entire surface  122  of rim  120  could be similarly divided into similar sectors. Each sector  122   a ,  122   b , . . . ,  122   n  has a given area “A” for its portion of surface  122  of rim  120 ; and each abrasive piece or wafer  150  covers a predetermined portion “W” of each sector area “A”. The remaining sector surface area “R” (shown cross-hatched in FIG. 12) that is not covered by an abrasive piece or wafer  150  provides a space over and through which fluids can flow to cool the grinding disk, and articles to be ground and to carry away “swarf”. 
     In FIG. 12 abrasive pieces  150  are spaced one adjacent the other and the covered area “W” equals a maximum percent of area A; while in FIG. 13 abrasive pieces  150  are spaced one from the other and covered area “W” is a lesser percent of area A then that for the configuration of FIG. 12. A percentage of covered are “W” ranging between 60 to 80 percent of sector area A is preferable to maximize grinding efficiency utilizing grinding disks according to the instant invention; while a percentage of covered area “W” ranging between 10% and 90% of the sector area could provide acceptable grinding. 
     FIG. 13 shows yet another embodiment of configuration of abrasive pieces  400  and arrangement of pieces  400  on a surface  410  of a rim  420  of a grinding disk  430 . Abrasive pieces  400  are shown with an octagonal, non-circular, configuration. Pieces  400  are otherwise fabricated from the same material as pieces  150  and to similar dimensions. Other peripheral configurations may be utilized. In addition, pieces  400  are applied to surface  410  of rim  420  in the same manner that abrasive pieces  150  are applied to surface  122  of rim  120 . Rim  420  is however wider than rim  120  and abrasive pieces  400  are applied to surface  410  in spaced relationship so as to provide for at least acceptable grinding as hereinabove described and preferably so as to maximize grinding efficiency as hereinabove described. 
     From the above description it will thus be seen that there has been provided new and novel grinding wheels and grinding processes. 
     It is understood that although I have shown the preferred embodiments of my invention that various modifications may be made in details thereof without departing from the spirit as comprehended by the following claims.