claim is: 1. In a finishing machine for slab materials comprising a feed mechanism to actuate a slab along a given path of operation, grinding units to engage an approaching ed-e of said slab each comprising a housing structure to support a power unit, a grinding wheel having circumferentially located grinding membersthereabout, and a means to connect said power unit to drive said wheel, and a frame structure to collectively support said grinding units in a given relation to position said grinding members of the wheels directly within the path of the advancin.edge of said slab to edgewise cut into the slab, said frame including adjustable guide means to movably carry all of the grinding units toward or away from the slab path, and adjustablemechanisms each interposed between the iiidividual housing structureg of said grinding units respectively and said frame structure to independently fix the position of the separate grinding members of the grindin.- units in a given relation with respect to the frame and to the path of travel of said slab, said adjustable mech,-nisms each comprising an orientation element integrally carried by one of said structures, together with regulatory means on the other of said structures connected to shift said orientation element into selected fixed positions. 2. In a finishing machine as in claim 1, wherein independent synchronized elevating and lowering mechanisms are connected with said adjustable guide means of gaid frame structure to selectively orient all of said grinding members of the grinding units in a given intercepting elevation with respect to the path of movement of said slab. 3. In a finiswng machine as in claim 1, wherein oscillatory mechanism is interposed between said frame structure and said gnndin- units to bodily actuate all of said grindin.- units and their connected grinding wheel grinding members along given paths described transversely to the movement of said slab. 4. In a finishing machine as in claim 3, wherein said grinding wheels are closely spaced to provide overlapping oscillatory action to cause said grinding members of the wheels to duplicate the grinding operation across predetermined common areas of the slab surfaces being worked by said machine. 5. In a hard slab surface truing machine comprising, in combination, means to orient and to actuate a slab in a given direction along a horizontal plane of operation, and a plurality of grinding heads having grinding wheels provided with marginal cutting instrumentalities to horizontally engage and to cut away a surface portion of said slab, and swingable mechanism to bodily support said grinding heads comprising means to oscillate each of said grinding heads coincidentally with and along said same given plane of operation of said slab, said swingable mechanism functioning to oscillate said heads in parallel relation through individual arcs traversing portions below the original surface of said slab. 6. In a hard slab finishing machine as in claim 5, wherein said grinding wheels of said heads are closely spaced with respect to each otlier whereby said cutting instrumentalities of said wheels operate in overlapping arcuate patterns to duplicate the grinding action in alternate opposite directions over certain predetermined areas below the original surface of said slab. 7. A slab surfacing machine comprising a feed mechanism providing multiple supporting and actuating means to engage the under face of a slab and to feed said slab edgewise along a fixed path, grinding mechanisms including finishing wheels having radially outer marginally connected cutting instrumentalities thereabout arranged for peripheral contact and for disposition in the path of travel of said slab, said finishing wheels each occupying a common elevation to dist)ose said cutting instrumentalities in a predetermined cutting plane of operation to edgewise intercept an edge of said slab along a reference plane bearing a given elevated relation with respect to the supported underface of the slab, and adjustable gauge rneans ca'rrying said grinding mecbanisms to regulate the maximum predetermined downward positions of said finishing wheels in relation to the slab to edgewise engage and to remove a complete surface layer of material from said slab along a true and continuous single surface coincident with said reference plane Nvhile said slab is edgewise actuated along said fixed path against the periph10 eries of and beyond the locations of said finishing wheels by said feed mechanism. 8 ' In a hard slab finishing machine comprising, in combination, means to actuate a slab in a given direction along a predetermined plane, and a plurahty of grinding 15 heads havin- grinding wheels adapted for coplanar operation to engage and to finish a surface portion of said slab, and swingable mechanism to support aR of said grinding heads comprising means to osciuate each of said grinding heads along the general plane of operation of 20 said slab and in individual arcs traversing fractional portions of the surface of the total widtli of said slab, and power means to drive said swingable mechanism comprising a motor, a rotary disc, drive means actuated by said motor and connected to drive said disc, and a crank on 25 said disc connected to operate said swingable mechanism, 9. In a hard slab finishing machine comprising, in combination, means to actuate a slab in a given direction along a predetermined plane, and a plurality of grinding heads having grinding wheels adapted for coplanar opso eration to engage and to finish a surface portion of said slab, and swingable mechanism to support all of said grinding heads comprising means to oscillate each of said grinding beads along the general plane of operation of said slab and in individual ares traversing fractional por35 tions of the surface of the total width of said slab, and power means to drive said swingable mechanism comprising a motor, a rotary disc, drive means actuated by said motor and connected to drive said disc, a crank on said disc connected to operate said swingable mechanism, 40 and releasable pivotal means to connect said crank with said disc, said pivotal means being carried in an opening in the disc, said disc opening being located at a given radius with respect to the axis of rotation of said disc and said disc being provided with other openings located at .4 to, different radial distances from the axis of rotation of the disc to interchangeably receive said pivotal means to thereby selectively vary the crank throw and the amplitude of the arcs of oscillation of the grinding heads. 10. In a hard slab finishing machine comprising, in 50 r-ombination, means to actuate a slab in a given direction along a predetermined plane, and a plurality of grinding heads having grinding wheels adapted for coplanar operation to engage and to finish a surface portion of said slab, and swingable mechanism to support all of said 55 grindin,- heads comprising means to osciuate each of said grinding heads along the general plane of operation of said slab and in individual arcs traversing fractional portions of the surface of the total width of said slab, and power means to drive said swingable mechanism com60 pr!slng a motor, a rotary disc, drive means actuated by said motor and connected to drive said disc, and a crank on said disc connected to operate said swingable mechanism, said swingable mechanism having extensible mechanism connected therewith to selectively regulate the posi65 tions of the grinding wheels of said grinding heads in a direction normal to the plane of operation of the slab. I 1. The method of finish cutting at least one face of a rought cut slab of hard material having surface undulations and rough areas thereon primarily as a result of the 70 rou,lh cutting thereof, whereby said finish cut establishes a smooth, true, and coplanar level surface on said one face of the slab, which comprises orienting said slab of material to stabilite and to support said one face thereof at a predetermined elevation, providing a cutting instru't 5mentality to engage the slab for translatory coplanar

grinding along a reference plane occupying a given maximum position beneath the general exterior surface plane of the face of the slab with said reference plane occupying a positi6n to include all of the undulations and rough areas of the one face of the slab, and causing relative intercepting bodily moveme--it between the grinding instr-umentality and said slab alon.- said reference plane to completely eliminate the material of the slab above said reference plane including all the undulations and rough areas appearing on the slab face being processed. 12. The method of providing a smooth, true, and coplanar level surface upon at least one face of a rough cut slab of hard material having surface undulations and rough areas on said one face, which comprises orienting said slab of material to stabilize and to support said one face thereof for movement -in the direction of the general plane of the slab, providing a cutting instrumental;ty directly in the path of movement of said slab for bodily contact and coplanar grinding along a reference plaiie occupying a given maximum position with respect to the thickness of the slab with the reference plane bearing a nredetermined vertical relation with respect to the exterior limits of the face being pr<)cessed to include all of the undulations and rou,-h areas of the one face within the path of action of said ctitting instrumentality, and causing relative bodily motion between said slab and said grind;ng instrumentality alopg the general plane of the slab and in a continuous advancing direction along the refer-.nce plane to completely remove all of the material of the slab along said one face including all undulations and rou.-h areas appearing on said slab face. 13. The method of finish cutting at least one face of a rough cut slab of hard material having surface undulations and rough areas thereon primarily as a result of the rough cutting thereof, whereby said finish cut establishes a smooth, trtie, and coplanar level surface on said one face of the slab, which comprises orienting said slab of material to stabilize and to support said one face thereof at a predeterm@'@ned elevatio-,i, providing a cutting instrumentality to engage the slab for translatory coplanar grinding along a reference plane occupying a given maximum position beneath the general exterior surface plane of the face of the slab with said reference plane occupyin@ a position to include all of the undulations and rough -- ;as of the one face of the slab, and uniformly actuatin' a, 'd sa, slab of material in a continuous rectilinear direction along the reference plane to intercept said grinding instrumentality while causing said grinding instrumentality to arcuately oscillate transversely to the path of movement of said slab for convex removal of the material of the slab above said reference plane including all of the undulations and rough areas appearing on the slab face being processed. 14. In the method of claim 13 with the use of a number of grinding instrumentalities to provide multiple arcuate cuttings on the slab and wherein said grinding instrumentalities are arcuately oscirated to provide adjacently overlapping cuttings of the slab material coincidently with the reference plane of the slab. 15. In the method of claiin 13 which includes a grinding instrumentality providing coacting multiple cutting facilities to cause said convex removal of the slab ma. terial along the reference plane and to simultancously surface finish the newly established true and level slab face remaining in the wake of the convex material removal of the slab undulations and rough areas. 16. A machine for surface cutt:mg and surface trumg a rough cut slab of hard material having exterior surface undulations and rough areas thereon comprising mechanism to support and to orient a slab in a given plane, and grinding apparatus disposed in a predetermined relation with respect to said slab comprising a frame structure carrying a plurality of grinding heads thereon, said heads each compfising a housing structure, a power unit, a grind2,985,989 10 ing wheels for operation in a fixed plane with respect to said housin.- structure and in relation to the oriented slab, and drive means connected between said motor and the rotary means, said frame structtire incorporating guide means to slidably accommodate the housing structures of eqc-h head for movement toward or away from the slab plane, and independent adjustable abutment means for each head interposed between the housing structure of the head and said frame structure to bodil@ support said 10 head to orient its grinding wheel in a given vertical relation with respect to the slab, said grinding wheel having circumferentially arranged grinding elements for disposition below the upper surface level of the slab to a point coincident with a reference plane including all of the 15 slab undulations and rough areas, and apparatus connected to cause relative movement between said slab and said heads to actuate the circumferential grinding elements of the gr-.nding wheels against and into a peripheral edge of said slab to remove all of the slab material 20 lying above said reference plane to establish a smooth coplanar surface upon the slab. 17. In a machine as in claim 16 wherein said fraine structure is supported upon vertically cooperative telescoping members to@ bodily elevate or lower the entire 2r, grinding apparatus relatively to the plane of the slab. 18. In a machine as in claim 16, with the addition of extensible means that are connected with said frame structure for the bodily elevation or lowering the entire grinding apparatus with respect to the oriented position of the 30 slab. 19. In the combination of claim 16, with the addition of cooperative extensible means connected at spaced points on said frame structure to bodily elevate or bodily lower the entire grinding apparatus with respect to the oriented 35 position of the slab, and power operated means including synchronized screw members are connected to actuate said cooperative extensible means in unison. 20. A mechanism for providing a smooth and true coplanar surface on at least one face of a rough cut slab 40 of hard material having undulations and rough areas on said one face, comprising, in combination, supporting means to orient said slab with its one face located at a given elevation, a grinding unit having a wheel including coacting cutting instrumentalities located in angular rela45 tion with respect to each other adapted for removal of slab material along a horizoiital reference plane, means to adjust said grinding unit for operation coincident with said reference plane, the location of said reference plane being vertically inwardly from the general exterior sur50 face of the one slab face an amount to include all of said undulations and rough areas, and apparatus to cause relative movement between said grinding unit and said slab to cause said unit to remove slab material from along Lhe reference plane, certain of said cutting instrumentali55 ties functioning to cut way slab material from above said reference plane and certain other of said cutting instrumentalities functioning to Msh the newly developed coplanar surface on said one face of the slab. 21. In a mechanism as in claim 20, with the addition 6( of laterally swingable supporting means to carry said grinding unit and power mechanism to actuate said swingable means in oscillatory fashion across said slab, and wherein said apparatus causing relative movement between said grinding un'@t and said slab actuates the latter along 6r) a rectihnear path under said swinging grinding unit. References Cited in the file of this patent UNITED STATES PATENTS 1,40 1,832 Tayl or ------ ---------- Dec . 27, 192 1 70 1,63 9,012 Tilly er et al ------------- Aug . 16, 1927 1,962,766 Crowley et al - ---------- June 12, 1934 2,673,423 Boyet et al - ------------ Mar. 30, 1954 2,799,974 Andrysick et al - -------- July 23, 1957 2,847,804 Calkins et al - ---------- @Aug. 19, 1958 ing wheel, rotary means connected to support said grindis 2,890,551 Dalton ---------------- June 16, 1959

'r T 21985@989 L) ilited States Patelit Office 2,985,98 9 SLAB SURFACING MACH]NE. Lloyd H. Knost, % L. H. Knost Co., P.O. Box 415, Carthag e, Mo. Ffled July 15,1958, Ser. No. 748,741 5 21 Claims. (Cl. 51-55) Th,.s iwvention relates to a surface finishing machine for varioiis kipds of hard materials. More specifically, the invention is directed to a machine 10 for finishing a surface area of a slab composed of a materi@l such as marble, grinite, terrazzo, -lass and of other analogo us substances. Thus, while various other work pieces or slab materials may readily be worked upon with a machine of this character, the subj@-ct matter hereinafter 15 will generally refer to the slab material stich as marble for the sake of convenience and consistency of description. Various laborious hand finishing methods have been used over the past years to finish surfaces on slab materials and stich methods are still resorted to in some in- 20 stances. To redtice the tedious and time consuming ways of manually finishing hard slab materials, various mechanical methods have been developed to provide means to surface finish slab materials. The me--hanical systems developed are fun damentally 25 such as to provide mechanisms that guide grinding wheels over and seated upon a slab of stone, marble, -ranite or the like. Such mechanisms employ what is known as floating types of grinding heads which make no allowa.,ices whatever f6r the irre.-Ular surface contours pre- 30 sented by a particular slab that is being worked upon. The heads actually contoiir finish the slabs. When slabs of stone or mable, as an example, are ctit at the quarries by gan.@ saws, the surface face areas are not at all true and level, but a slab stirface will have low 35 spots apd high spots over various portions of the faces thereof. With a floatir@g head type of a grinding spindle, the grinding wheel is made to engage upon the surface of such a slab for the surface finishing and/or polishing operatio n of a face thereof. As the slab passes under 40 the - rinding wheel, the wheel wiII follow the adjacent surface coiitour of the slab whether convex or concave as develop ed from the previous gang saw operation. The final outcome is a wavey or undulant final surface on the finished slab. No uniformity exists in the slab thickness and the finished surface is not a t@rue, flat or coplanar area. 45 One of the objects of the present invention is to provide a slab surfacing machine that does not follow the undulati ons of the surface of a slab of material, but a machine that is constructed and arrangbd to edgewise 50 shave or grind off a fixed increment of material from a slab to level off the slab top along a given thickness in relation to the urderside of the slab. Thus high points and low points on a slab surface have no effect on the operativ e cutting elevations of the grinding wheels. In other words, the grinding heads are set to cut a triie horizontal swath of material from one surface of the slab that will provide a gauge cut o'L determinable character, takin.- off the excess slab material at the convex areas and the lesser but appreciable slab materiil at the 60 cone,ive areas of the slab. This is considered a new and novel solution to a hitherto uncontrolled and unptedictable slab surface finishing practice. It is another of the objects of the present machine to provide an efficie-@it assembly of coacting mechanisms that 65 will fu,Iction consiste-.itly to produce a given or predetermined true and level surface finish on a slab material and at the same time exercise a high degree of c6ntrol that will provide such a slab with a determinable maximtim thickness and accurate level surface finish when 70 complet ed. Another object of this invention is to provide a finishPatented May 30, 1961 2 ing mechanism to smoothly surface a slab material utider certain controlled compound motions of oriented g@rinding mechanisms which under operation cooperatively act to quickly and finely mill off selected coplanar increments of surface material from a slab to ob.tain a true high gloss fiiiish on the work piece. As another object, the machine provides means to manip:ulate and bodily actuate a batiery of grinding spindles together in concerted unison with their associated grinding or polishing wheels and in an oscillatory fashion in a transverse direction across a slab of material- while the latter is being moved rectilinearly over a roller bedlor other instrumentality supporting such a slab. Another object is to provide a slab finishing machine with -me I chanism including multiple grinding heads h I aving the finishing @vheels thereof closely and adjacently positioned where,by, under oscillation, the action provided produces a considerable percentage of overlap of the wheel action upon common slab areas that are serviced by slich adjac'ently positioned wheels. Other objects of this i I nvention reside in the constrtiction of the novel arranj-zement of the various mechanisms to 6btain the close iolerance adjustments that benefit the consistent end resu' ts obtained; the manner of the positive level Support of the grinding heads and the incorporated micrometer manual adjustment means of the@ individual heads; the oscillator-y mechanism employed to actuate the battery of heads; and in the combinations of mecham'sms that to@ether pro4uce the finished work pieces as will hereina'fter be described with greater particulanty. All other objccts and advantages relating to the material slab finishing machine of the present invention will hereinafter appear in or become evident from the follow.ing more detailed description of the machine having reference to the drawings disclosing a preferred construction of the macwne and forming a part of this specification. In the drawings: Fig. I is a side elevational view of a slab material sqTfacing and finishing machine inc4c@rporating the principles of the present inventive concept; Fig. 2 is a front end elevational view of the machine as the same appears when viewed from the right hand end of Fig. 1; Fig. 3 is a.fragmentary plan view of the grinding head assembly section of the machine; Fi.@. 4 is a vertical cross sectional view of one of the identical spindle -rinding. head assemblies as such apparatus appears when viewed along the plane of the line 4-4 in Fig 2" Fig. 5 is a bottom plan view of a fragmentary portionof the grinding wheel of the head shown in Fig. 4; Fig. 6 is an enlarged radial sectional view of a portion of the grinding wheel per se to illustrate certain strurtural details thereof; and Fig. 7 is a diagrammatic plan view of the grinding mechanisms of the present invention to better illustrate the oscillatory action and operation thereof, this view omitting the center grinding heads for the sake of clarity, but showing the two outer end heads as being oii th6 same center to center spacing that exists between the re.spective, miiltiple heads 6f this appatatus. While the foflo'wing description will be directed to the embodiment irustrated in the drawings, certain deviations in the combination of elements employed are conlq;idered perinissible that will not depart from the general fundamental scope of the invention. As one example, wliild only four gr@inding units are shown in the drawings, this number may be readily incr,eased to any number under various conditions of operation together with a change in grinding wheel sizes. Also the amplitude of the oscillatory swing may be greatly varied and the opposite out-

3 wardly end units may be made to ride over or off the edge portions of the marble slab and need not necessarily be Umited to action within the physical confines of the slab material. And further, while each head assembly is an integral and complete unit, the direction of rota- 5 tion of the grinding wheels may be in either direction as may be brought about through reversible motors or by other suitable reversible drive means. Thus, every other spindle may be made to drive in an opposite direction from its next adjacent spindles to produce altemate reverse 10 actuation of the grinding wheels. Under the reversible ddve conditions noted, it is also possible to have the two left hand spindles in Fig. 2 driven in one direction, while the two right hand spindles are driven in the opposite direction. With such selective 15 rotational benefits of a battery of grinding spindles, it is possible to provide better control of the dust and loose slab material and/or fluid and accompanying water employed in the grinding operation as well as to obtain the most ben,-ficial final results on slabs of various materials 20 that are fed into the machine for surface grinding and/or polishing to a given predetermined sarface condition. One of the chief advantages of the opposite or counterrotation of the spindles and their associated grinding heads relates directly to the obtainment of a simple true 25 and accurate rectilinear feed of the siab mateiial that is being surface finished. A single rotating spindle, or a number of spindles all rotating in one - direction, will impart a side thrust against the slab material to urge the slab out of its intended path of operation. Some of the 30 machines now in use havin.- single heads actually resort to clamping the slab in a guided frame to prevent the slab from being thrown out of the machine. Thus with the selected counter-rotation of the spindles and grinding wheels as shown by the arrows in Fig. 3, as 35 oiie example, the side thrust upon the surface of the fragmentarily shown slab is substantially nulefied and eliminated. The slab can be fed over the rollers under its own weight along a true course under the grindinmechanisms without the use of guiding and/or clamping 40 means. Referring to Figs. 1, 2 and 3 of the drawings, the various coacting mechanisms of the machine are all carried upon a framework I supported upon a rigid frame base 2, with both units 1 and 2 including suitable vertical, 45 horizontal and diagonal structural members to create a solid and stlirdy machine frame to support the coacting mechanisnis of the slab surfacing machine. A plurality of rollers 3 are jour-nafled in bearings 4 a,id 5 cai-ried upon frame sides 6 and 7 to create a slab 50 supporting bed or reactionary structure to support the work pieces such as marble slabs or the like at a given and fixed elevation as determined by the upper peripheral circumfercntial surface limits of the multiple rojlers. The rollers 3 are normally all equidistant from each other as 55 best shown in Figs. I and 3 with the exception of certain rollers 8 and 9 that underly the locations of the grinding spindles and the superimposed grinding areas of the slab. All rollers are positively driven to provide the feed mechanism to advance a marble slab such as 10 under 60 its own weight over the machine bed in edgewise relation 'it a g'veI ii elevation aiid toward the grinding wheels of the spindles. In this connection it might be emphasized that the rollers are constructed of a material having good frictional characteristics to readily grip the underside of 65 a slab aticl to advance the slab in a straight line in a reet:@'iticai- direction along the length of the machine and Iver t'iie bcd. The rollers may, for example, be made of a rubber or rubber composition material of very limited i-esiliency but having good frictional surfaces. 70 The roller drive is initiated from a motor 11 driving its motor shaft 12 that is connected with shaft 13 through coupling 14. Shaft 13 is an inclusive driven part of variable f,,peed trapsm@ ission 15 that drives a chain ,-pi-oct.--t v,,heel 16 by means of the transmission shaft 17. i-5 4 A chain IS connerts a sprocket wheel 19 with wheel 16, the sprocket wheel 19 being secured to the roller shaft 20 of the roller 9. The drive to the other rollers is then suitably transmitted by means of the laterally and alternately offset chain drives 21 and 2Z that are actuated by suitable sprockets connected with the opposite end of the shaft 20 of roller 9 as best seen in Fig. 3. Additionally alternately staggered chain drives 23 and 24 are employed to continue the positive ddve to the other rollers 3 of the machine in the manner also best illustrated in Fig. 3. With this arrangement, the motor 11 drives aH of the rohers in concerted and positive manner. Motor 11 may be reversible, if desired, should rectilinear oscillation of a slab be needed or required under certain conditions of usage or operation. With the variable speed transmission 15, the roller speeds can be changed to vary the rate of slab feed. The grinding apparatus is best illustrated generally at 25 in Figs. 1, 2 and 3, and this apparatus is equipped with multiple grindin@ heads such as 26, 27, 28 and 29 all supported in an overhead box frame 30. Frame 30 is provided with vertically spaced supporting ears or arms 3131 and 32-32 at its ends and vertically arranged pivot shafts 33 and 34 connect the respective ears with equal length sets of supporting arms 35-35 and 36-36. The sets of arms 35-35 and 36-36 are mounted in fixed relation upon respective pivot shafts 37 and 38 that are journalled in vertical positions in a tubular cross frame 39 attached at its ends with parallel and vertically positioned supporting sleeves or tubes 40 and 41 that operatively telescope into coacting orientation and guide sleeves or tubes 42 and 43. The sleeves 42 and 43 are stationarily secured in outboard relation upon vertically spaced frame parts such as parts 44 and 45 for tube 42, parts 46 and 47 for the tube 43, such frame parts including other suitable structural elements for stabilization and rigidity. Referring now to Figs. 1 and 3, it should be noted that the sets of arms 35-35 and 36- 36 provide means whereby the box frame 30, together with the associated heads are adapted for bodily oscillation in an arc transversely of the machine over and across the path of advance of a work piece or slab that is carried upon the machine roller bed. Box frame 30 moves at right angles to the slab direction, as a unit, and the heads 26 to 29 describe individual arcs within the limits of their amplitude of oscillation. The general action may be well understood with reference to the diagrammatical layout - ,ippearing in Fig. 7. A drive mechanism 48 provides the actuating means for the controlled oscillation of the -rinding apparatus 25 and coniprises a motor 49 mounted upon a platform 50 secured to the cross frame 39, the motor driving a pulley 51 having a transmission chain or belt 52 that rotates the belt wheel or pulley 53 of a speed reducing transmission 54. Transmission 54 includes a vertical drive shaft 55 that his a crank disc 56 to pivotally receive one end of a crank 57. The connection between menlbers 56 and 57 is made by means of a suitable drive pin 58 that may be connected tbrough any one of a number of openings 59 that are located about the disc 56 and on different radii with respect to the axis of rotation of the disc. This is done for purposes of varying the amplitude of the stroke of the crank 57 according to the opening selected to receive the crank drive pin 58. The other end of the crank 57 is swingably secured for partial segmental actuation by means of a spindle or pin 60 that is carried by the outer end of an arm 61 wbich is coniiected with the grindidg apparatus 25. Arm 61 preferably comprises a contiguous extension or integral part of one of the arms 32. Thus the oscillatory acttiation o.' the grindin.- apparatus 25 is under the full control of the actuating mechanism 48 that is powered by the motor 49. With thecooperative action of the speed selcctions possibk- with the selective speed transmission 54 and with the stroke adjustment provided by the openings 59 in disc 56, considerable variation in the action of the grinding appa-

2,985)989 5 ratus is possible wher6by to obtain the. desired results to meet conditioii@ to best suit the work piece characteristics and to establish a satisfactory final stirface finish upon the slab being worked. The more specific details of construction of each of 5 the grinding heads 26 to 29 per se may best be seen by reference to Figs. 4 to 6. Each grinding head comprises a motor 62 mounted upon an annular table or open center base 63 supported by a sleeve 64 secured to a structural div.;sion @late 65. A circular sleeve 66 is attached 10 in depending relation to plate 65 and extends in vertically guided relation through upper and lower aligned openings 67 and 68 formed thr6ugh the top and bottom walls of the box frame 30. Motor 62 furnishes the power for driv'mg the grinding wheel 69 associated with the head 15 structure described. Power is transmitted. through the motor shaft 70 into a coupling 71 that is connected with the adjacent end 72 of a power transmission shaft 73. Shaft 13 is journalled in upper and lower aligned bearihgs 74 and 75 which are re8pectively mounted upon plate 20 65'and upon the lower end of the sleeve 66. The lower end 76 of @haft 73 is secured or otherwise stiitably keyed to a drive mandrel or fixture 77 and the latter is held in place upon shaft 76 by means of a lock nut 78. An annular plate 79 is mounted uppn the lower face of the man- 25 dre.1 77 with nuts 80 and plate 79 includes a downwardly directed peripheral ring 81 to orient and receive grinding wheel segments 82 that carry pairs of arcuately formed se,amental diahlond strips 83 and 84. Each of the segments 82 are suitably secured -to the plate 79 by means of 30 nuts 85. Attention is also directed to the beveled bottom outer edge or face 96 that is provided on each segment 82 to dispbse its radia.11y outer strip 83 in a canted relation with respect to the strip 84 whereby a beveled cut is edgewise 35 made into the surface are@ of a slab 10 to be automatically followed by a sizing or fin.al dimensional cut by the nonbeveled diamond strip 84 located on the face of its seg I inejit 82. Suitable radial sweeper segments may be employed on the segments with the strips 83 and 84 to 40 assislt in cleaning up the slabs. Mch grindin wheel assembly includes an open top an9 nular hood structure gr shield 87 bolted to the top side of plate 79 and f6rmed to surround the conical exterior 88 of the mandrel 77. Plate 79 is provided with openings 45 89 that communicate with the chainber 90 defined by the shield 87 and mandrel 77. The openings 89 are each enlarged downwardly to aid in drawing the water down from chamber 90 into the diamond cufting area or zone under operation of the grinding heads. 50 A suit;able water supply conduit 91 is carried by the box frame 30 t6 direct water supplied through a hose 92 into the chamber 90 to supply water through openings 89 to the grindin,- zone on the slab. Various other supported dust and fluid shields such as 93 in Fig. 2 may be used 55 to confine and localize a good deal of the free mixture of marble or slab dust and water that surrounds the grinding wheel locations. Suitable trough means such as 94 are further employed beneath the grmding areas for the collection of free materials coming from the grinding wheels. 60 One of the flirther advantageous arrangements embodied in the -rinding macwne has to do with the matter of positive vertical adjustm.ent, of the grinding heads 26 to 29. It is important to initially establish a good horizontal alignment of the grinding wheel faces of the multiple 65 heads. Since each head is oriented and vertically guidable by means of the sleeve 66 riding within the box frame openin.gs 67 and 68, a fme adjustable abutment unit bt @top means such as 95 is connected with each head as6 nuts 99 and 100 providing regulatory @ riieans. as instrum&ntalities to positively fix the position of the plate,:65 relatively to the stud 96. Stud 96 is rigidly suppqrted with its end 101 fixedly connected with a plate 102 that is secured to the top of the b6x frame 30 as best Hitistrated in Fig. 4. Vertical adjustment in small increments is readily possible with the adjustable abutment stop means such as 95 to thus provide a mantial adjustment for the vertical positional regulation of the associated head in relation to the supporting fraine 30. Supplementing the above described adjustment is the larger and more comprehensive mechanism that bodily elevates or lowers the entire grinding head apparatus relatively to the slab carrying roller bed used to feed a slab material along the machine. This latter overall vertical adjusting mechanism is best shown in Figs. I and 2. This adjusting means is a power dri-,,en apparatus that may be controlled for given height changes or variations by on and off energizations of'the motor for selected intervals or under conventional limit controls. The head agsembly elevating apparatus comprises a selectively reversible motor 103 having a belt drive 10@4 to drive a transverse cross shaft 1105 that connects with speed reducing transmissions 106 and 107 throu.-h suitable coiiplings 108 and 109. Each transmission is provided with a drive snaft such as 110 and III respectively that drive chain or belt means 112 and 113 to rotat6 vertical jack screws such as 114 and 115 that are located on the axial centers of the telescopic means 40-42 and 41-43 described to support the grinding heads. Screws 114 and 115 operate through orientation bushings 11-6 and 117 carried upon frame parts 45 and 47 to hold the screws against endwise vertical displacement. The upper free ends of screws 114 and 115 thread through nuts 118 and 119 secured to the lower ends of the sl6eves 40 and 41 as seen in Fig. 2. By energizing motor 103, the drive is completed by the mechanism described to the jack screws 114 and 115 which will draw the nut@ 118 or 119 upwardly or downwardly according to the direction of operative rotati6n of the motor 103. This will produce relative motion between the sleeve sets 40-42 and 41-43 to change or regulate the elevation of the box frame 30 and the gupported grinding heads 26 to 29 carried by such overhead frame 30 and 40-41, the latter units together forming a U-frame structure. From the above description it will be apparent that the slab surfacing machine provides a grinding or'finishing structure that edgewise removes a complete surfac6 increment of material from a rough cut slab oriented in a given supported relation to the grinding structure. This action is well illustrated in Fig. 4 wherein a slab of m@teri@l is being advanced in the direction of the arrow and a grinding wheel is disposed in a given relation in the patli of the slab to edgewise cut into and across the top face of the slab in a coplanar manner to establish a smooth, true and level finished surface along a division line on the slab. Fig. 7 is used to further ghow how the grinding wheels are arcuately oscillated in paths transversely related to the rectilinear path of travel of a slab, the oscillations of the wheels having amplitudes to cause overlapped cutfings. The cuttings are made convexly directed against, the pata of the slab advance to thus obtain continuous compound motion of arcuat I e sawtooth cuttingg across @the slab f,,ice by each of the grinding instrumentalities. The foregoing @escriptibn relates to one preferred embodiment of the invention. Certain changes in the combinations and in the ind,ividual elements thereof are consembly for vertical orientation of the head in relation to 7o tem lai6d without departing from the fundamental corip the b6x frame 30 and to prevent rotation of the head cept of the invention herein diselosed@ The exteiit of relative to the frame 30. The abutment unit and adjustsuch modifications shall, however, be gov,erned by th-@ ing means 95 com@rises a threaded upright stud 96 loosebreadt h and scope of the appended claitned subject matly positioned within an opening 97 formed in an orientater directed to a slab surfacing machine of th6 @fesent tion 6lement or ear 98 on plate 65 with opposite outward 75 iii vention.

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