US1973177A - Grinding machine - Google Patents

Description

Sept. ll,- 1934.

B. E. ROCKHOFF GRINDING MACHINE Filed Jan. 19, 1931 5 SheetS-Sheet l hm. ww

/VEN-TOR. I 55H7 5. 19am/WFP BY mail, /Mul- A TTORNEY Sept.. M, 1934..

B. E. ROCKHOFF GRINDING MACHINE Filed Jan. 19. 1931 5 Sheets-Sheet 2 OOOOOOOOOOOOOOOOOOOOOOOOOOOOO 00000000 o .v oo oooS'foO INVENTOR. 7E/PT E FDL-UFF A TTORNEY5 f sept., 11, 1934. 1 B E ROCKHOFF 1,973,177

GRINDING MACHINE Filed Jan. 19g 1951 5 Sheets-Sheet 3 i /m j INVENTOR.

BY W

A TTORNEY Sept l l 1934 a. E. ROCKHQFF GRINDING MACHINE Filed Jan. 1,9. 1951 5 sheets-sheet 4 Egt INVENTOR. 75N E UMHUFF Sepkll, 1934. Bl E. RQCKHOFF 1,973,177

' GRINDING MACHINE Filed Jan. 19, 1951 5`sheets-sheet 5 l N VEN TOR. ...17E/E17 E UCKHUF'F A TTORNEY5 fill) Patented Sept. 11, 1934 fUNlTED STATES GRINDING MACHINE Bert Rockhofl, Detroit, Mich., assigner to Detroit Steel Products Company, 'Mich'., a corporation of Michigan Detroit,

Application January 19, 1931, Serial No.,509,7188

11 Claims.

"This invention relates to :grinding machines and more particularly to machines vof this :type especially designed for chamfering yor bevelin articles of manufacture.

While the machine about to tbe described may be used for ychamfering various .articles of manufacture, nevertheless, it finds particular utility When Aused in .the manufacture of vehicle leaf springs for chamfering opposite ends .of the latter :and to .this `end the invention consists in the provision of :a machine having .abrasive members so :arranged with respect to :each other as to :simultaneously .chamfer opposite ends f the spring barsas the latter are continuously moved in a predetermined path.

Another :object -zof this invention resides in the novel means employed for adjusting the relative positions of the abrasive members to .compensate for bars of varying length;

` A further advantageous feature .of the present invention resides in the provision of means operable upon manipulation vof .suitable adjusting mechanism for reciprocating the .abrasive members :during 1thegrinding operation.

A still further :object of :this invention sis attributed to the novel lmeans employed for gconveying the leaf spring bars tothe abrasive members andfalso the means for automatically feeding the bars 4to the conveying means.

A With the foregoing vas Well Aas other objects in view, the .invention resides ,in the particular construction .of 'the grinding machine which Will be .made .more .apparent as this .description .proceeds, especially When considered in connection with the `accompanying drawings, wherein:

Figure 1 is a sectional `side Aelevation .of amachine constructed in accordance `vvith `this invention;

'Figure 2 isY a central transverse `section v through the machine illustrated in vFigure 1;

Figure 3 is `a fragmentary .end `elevation of the machine illustrated in `.Figure 1;

Figure 4 `is a sectional view taken substantially on-,the 4line 4--41of Figure '1;

Figure 5 isa detail sectional view of apart of the machine illustrated in Figure 1;

Figure 6 is a fragmentary top plan view of the adjustable reciprocating mechanism for `the abrasive members;

Figure 7 is fa sectional View vtaken-on the .line 7-'7.of Figure 6;

Figurei is a fragmentary side -elevational vieW of a portion of the machine-showing @one Yof the abrasive members `in a different position;

.Figure Vis a fragmentary .side. :elevational view of the imachine .showing the :means 'for actuating the Work conveyors;

Figure 10 is a fragmentary plan view of one type of spring bar;

.Figure 11 is avieW similar lto Figure 10 showing another type of spring bar.

While the `machine illustrated herein and about to 'be described may :be :used for y,chamfering various `articles of manufactura nevertheless, it finds particular utility when employed in the manufacture of leaf springs -f'or chamf-,ering the opposite ends of `the spring bars. In detail, the machine illustrated herein comprises two frames 10 and 10a adapted to rest :upon `a suitable support and having .a bed portion 1-1 at the upper end thereof extending longitudinally of .the machine and supporting ,a pairof heads A12 and 13. The heads l2 and ,13 are mounted upon the bed for sliding movement relative to each other and carry :suitable abrasive members 14 and 15,- respectively, -in the form of rotatable grinding Wheels. 4The head l2 carrying the grinding Wheel ,le is fixed vto one Iend of the 4bed portion $11, While .the head A13 is slidably mounted upon suitable guides v16 for sliding movement toward and from the head 12.. For sliding :the head 1,3 relative ato fthe )head 1'2, I provide a :rack bar l?? ,secured to one side `of the bed vportion 11 of the fra-me in :a position to mesh 4with a suitable Apinion 18 fixed upon la rotatable shaft extending transversely :of the frame and having the end portion journaled in a vsuitablebracket A19 secured ftogthe head ,-13.. If desired, a suitable handle 20 maybe secured to one end of the/shaft for rotating the latter to effect a sliding movement of the head 13 upon `the `guides 16. 'The constructionissuch as to'permit varying the distance ,between the grinding wheels 14 and V15 to compensatefor spring bars of different length.

Inthe machine illustrated herein the spring bars to -be fashioned are :continuously moved transversely of the bed portion 11 fof :the fra-me between the heads 12 and 13 With the opposite end portions 4of the bars `so positioned lrelative to the grinding -Wheels 14 and `15 .as to pass beneath the latter. in this connection fit iis to be 4noted that vthe 4head l13 is so positioned relative to the head 12 that opposite Yends 4of the bars are slidably supported during movement transversely 'of the frame lupon the upper sur-- faces of the bars l241 and 22 secured respectively tothe heads v12 and 13. v As shown in Figure -1, y

the opposite end portions of the spring bars vare normally .yielclably maintained `into engagement with the supporting bars 21 and 22 by means of a pair of metallic strips 23 and 24 slidably mounted for movement in a vertical plane in the heads l2 and 13, respectively, for engaging the opposite end portions of the bars at points spaced. inwardly from the supports 21 and 22. The strips 23 and 24 extend transversely of the framell and the lower ends thereof are normally urged into engagement with the spring bars to be fashioned by means of suitable coil springs 25 acting upon the upper edges of the strips. Y

For moving the spring bars transversely of the machine, the heads 12 and 13 are provided with conveyors 26 and 27, respectively. The conveyors 26 and 27 are preferably identical in construction and, as shown in YFigure 2, compriseV flexible linear members 28 in the form of continuous chains preferably of the roller type and adapted to extend transversely of the frame between the grinding wheels 14 and 15. The

chains 28 are preferably provided at spaced points with laterally outwardly extending projections 29 which serve to engage the spring bars adjacent opposite ends thereof. As shown in Figure 1, the conveyors 26 and 27 are so arranged relative to their respective heads that the projections 29 engage opposite end portions of the spring bars at points spaced inwardly from the supports 21 and 22, or in other Words directly beneath the spring pressed strips 23 and 24 with the result that the latter also serve to maintain the bars in the path of travel of the projections 29. The production of the machine is materially expedited and manual attention is appreciably reduced by feeding the spring -bars to the conveying means by gravity. This is accomplished in the present instance by providing a pair of vertically extending magazines 30 and 3l secured respectively to the heads l2 and 13 and cooperating with each other to slidably support the opposite end portions of a plurality of superimposed spring bars. The magazines 30 and 31 are secured to the heads 12 and 13 at one side thereof and directly above the guides 21 and 22, respectively. As shown inFigure 2, the outlet or lower ends 32 of the magazines are spaced above the supports 2l and 22 a distance substantially equal to the thickness of the spring bars with the result that only one spring bar'at a time may be moved from the magazines. It will, of course, be understood that by positioning 'the magazines 30 and 31 directly above the supports 21 and 22 at one side of the machine, the same will serve to deliver the spring bars upon the supports 21 and 22 in operative relation to the projections 29 extending laterally outwardly from the chain conveyors 26 and 27. Itwill further be apparent from the preceding description that when the head13 is adjusted to move the magazines 30 and 31 the proper distance apart to accommodate spring bars of corresponding length, the

conveying means 26 and 2 7, together with the supporting bars and spring pressed strips, are automatically adjusted to assume their proper positions relative to the spring bars. In order to compensate for bars of `varying widths, the magazines are formed of spaced sections 31 and 32 mounted upon the heads for movement relative to each other to diminish or increase the distance therebetween. Adjustment of the sections may be accomplished by manipulating the screws 33'.

Each of the chain conveyors 26 and 27 are supported by a pair of sprockets 33 and 34 carried respectively by the heads 12 and 13. One sprocket of each pair is secured to stub shafts 35 journaled respectively upon the heads 12 and 13, while the other sprockets of each pair designated herein by the reference characters 36 and 37, respectively, are mounted upon a drive shaft 38 extending longitudinally of the machine frame. In detail, the sprocket 36 of the pair 33 is keyed or otherwise secured to the drive shaft 38, while the sprocket 37 carried by the movable head 13 is splined upon the drive shaft 38 for axial sliding movement relative thereto. As shown in Figure 9, the sprocket 37 is secured to a sleeve 39 which in turn is splined upon the shaft 38 and journaled in a bearing 40 carried by the head 13.

From the foregoing construction, it will be observed that the conveyors 26 and 27 are driven by the sprockets 36 and 37 and that the latter sprocket is capable of sliding movement with the head 13. The drive shaft 33 is driven by suitable reduction gearing 41 which in turn is driven by a prime mover 43.

Referring now more in detail to the heads12 and 13, it will be noted that the latter are identical in construction and the grinding wheels 14 and 15 carried thereby are rotated by suitable electric motors 45 arranged Within and secured to the base portions of the substantially U-shaped cradles 46. As will be more fully hereinafter set forth, the cradle 46 is mounted for movement in three directions, each direction being transverse to the other two. As shown in Figure 4, suitable pintles 47 are secured to opposite legs 48 of the U-shaped cradles 46 intermediate the ends of the legs and project laterally outwardly beyond the latter for receiving the cradle arms 49. rfhe lower ends of the cradle arms 49 are ixed by means of the pins 50 to thefpintles 47 adjacent theY legs 48, while the upper ends of the cradle arms are connected together by means of a shaft 51. As shown in Figure 5, the legs 48 of the cradles 46 vare provided with arcuate slots 52 adapted to slidably engage suitable bolts 53 projecting laterally inwardly from the cradle arms 49 and having the inner ends thereof threaded for receiving the clamping bolts V54. The clamping bolts 54 serve to engage the inner surfaces of the legs 48 upon opposite sides of the slots 52 for holding the cradle from movement relative to the cradle arms. it will be apparent from Figure 5 that the construction is such as to permit angular movement of the cradles about the pintles 47 relative to the arms 49 and since the grinding wheels 14 and 15 are carried by the cradles with the axes thereof arranged substantially at right angles to the axis of the pintles, it will be apparent that adjustment of the latter as specified above causes a corresponding variation in the angular relation between the grinding surfaces of the wheels and the ends of the spring bars. at which the ends of the bars are chamfered is regulated by adjusting the cradle relative to the'arnis 49 about lthe pintles 47 and in order that the ends'of the bars may be chamfered to a predetermined angle, suitable markings 55 may be inscribed upon the outer surfaces 56 of one of the legs of each cradle, representing degrees. The arrangement is such that if it is desired to chamfer the ends of the bars at an angle of 20, the bolts 54 are merely loosened permitting the cradles to bey swung about the pintles 47 In other words, the angle stationarymarksl on thecradlefarms. Whenv the desired adjustment has been accomplished, the bolts 54 arie `again tightened. securing the the desired angles.

' Each "of the cradles 46- and associated. parts thereof arev carried `by 'a iframe' .structure 58' 'comprising apair of framemembers'oe arranged upon-opposite sides of 'the 0cradles beyondthe cradle arms-49 and having anti-friction members .journaled thereon and `projecting laterally outwardly'therefromfor 'engaging suitable tracksl 61. The tracks 61 are in the form of 'inwardly opening grooves fashioned inthe 'opposite :sides oi the heads' .12 :and 1.3 and `adapted to entend longitudlinally of the machine frame or in 'the direction of 'adjustment 'of lthe' head v13. The construction 'is such' as to 'permit moving the grinding wheels 14. 'and f15 toward `and. from each 'otlie'rV for accurately-positioning the same relative tio-'the opposite ends Vof the spring bars. The "particular liiiearis `employed herein ffor' iaccomplishing the above adjustment `of `the grinding wheels 1'4 and 1l5 will be 'morefully hereinafter described. f

J ourn'al'ed upon-the opposite ends of `the'shafts 51` and 'piritles 4-'7 beyond vthe cradle arms 449 are suitable rol-ler bearings `62 adapted toziproject Within vertically elongated. "slots 63 formed in the trame Vmembers59 -adjacent the upper and lower ends thereof. The roller bearings 62 `are of Ys'uchdiameter as' to 'engage the vertical opposite Aside Walls Hof the `slots 63 t'vhich,` as Aprevious'ly stated, `are 'elongated vertically to :per-

mit movement of the `cradle harms y49, cradle 46 and "associated 'parts vin a vertical direction. Thus, it will be seen that the grinding wheels 14 and 15 are capable ofrmovementin -a horizontal direction, a `vertical direction 'and in ananeular direction; 4

. Movement of the cradles '46 and vassociated par'tsin a've'rtical direction relative tothe frame members V59 .is Jcontrolled 'by suitabie adjusting mechanism designated generally by `the reference L'c'haracter *64. The adjusting mechanism comprises a pair of arms l"t5 .pivotally mounted intermediate the ends upon Ashafts l66 larranged above the shafts 5'1 and` extending :between the j frame members .59 Ifor connecting the upper ends of the latter-. The inner vfende' 651 of the levers are apertured 'to 'receive 'suitable threaded Velements "68 Elllavfing; 'the lower 'ends thereof ljournaled upori the shafts ESL-interim@ diate .the endsv thereof as indicated at 69.

Threaded upon the upper "ends 4of the :elements 68 are suitable adjusting nuts F10 lha-ving portions engaging the lfree :ends 67er thelarmsf65 as clearly shown in rFigure 1 of 'the' drawings. Movement of the 'free ends 267 of .thelevers 65 by theweightfof the 'cradle and associated .parts is `restricted byv means oil suitablefstraps -71 hav-w ing Wheels 11.4 'and 1.5, the'adjustirig huts 70 aremerely loosened permitting the Acradle arms v4'9 Y the adjusting nuts "YZO are tightenedlcausing the From the foregoihgit will be observed elements 168 and Yasfa consequence the `cradles 46 to move upwardly relative Ito the frame niembers "59, since upward, 'movement fof. the outer endsvof theflevelrs 65 is prevented by the straps the operation oi `the machine, the'grind# ing wheelsV 141and15 are usually-so adjusted vertically that `the Vdistance between the grinding surfaces 'of the Wheels and the `supports 21 and 22 for the opposite `ends of the bar's is slightly less than the 'thickness of the 4bars' `with the result that the latter `upontraveling beneath the grinding wheels, moves the wheels, Atogetherwith the cradles and lcradle arms, upwardly within the slots 63. The arrangement is such that `the weight of the grinding wheels and associated parts 'such as thec'radles and cradle arms serves to insure a' grinding pressure `for lclriamie'ringthe ends-efthebars. In-order to insure a constant 'grirlrdiing pressure and at the `same time to controlthe amount of pressure, I provide counterbalancing springs 73 `having the upper ends thereof secured 'to the Ylevers 465 adjacent the outer `ends ci thesame and having the inner ends thereof anchored' in any suitable' manner to the heads 12 *and` 13fwith the result that these springs normally v'assist rasihg of fthe grinding, wheels 14 and 15 by the bars passing therebeheath.

Referring howto the operation of the machine as thus far described `and assuming that it is desired to charnfe'r oppositeends 'of bars of the type illustrated in Figure 1'0 having the side Walls of the opposite end .portions converging., it will be apparent that the rst operation is dto adjust the head 13 relative to the head 12 for moving vtliefsame:the proper distance apart to accommodate bars `of predetermined length. The bars are then `positioned in superposed relation with the ends thereof in the magazines 30 and31 `and `the grinding wheels 14 'and 15 are' accurately adjusted to position the grinding surfaces thereof in operative relation to the `converging Aend portions of `the spring bars;- I-n this connection itfwill be noted from the preceding description that the Wheels 14 and 15 are 'vertically adjusted relative to the ends 'of the spring bars `by`manipulating the adjusting means and are angularlyadjusted to chamfer the ends of the' `bars 'to a Vpredeterrnined angle' by manipulating vthe adjusting nuts 54. In additionfto `the -vertic'al'ahdangular adjustments of the :grinding Wheels 14 and15, the latter may be :adjusted in thel direction of their axes by moving the frames 58 carrying 'the cradles and grinding wheels longitudinally relative to the heads 12 and 13 uponthe tracks 61. This latter adjustment is accomplished by suitable threaded elements A carried by the heads 12 and 13 and having intermediate portions `thread'edly engaging suitableyokes 81 which in turn are pivotally' connected at the inner ends thereof t'o the transverse `framebars '72 of -the frames 58 as at 82.l The inner 'ends of the threaded elements k80` extend within the yoke's `81 and are secured Vto blocks 83 having a sliding engagement with thel yolresA for `guiding the saine during adjustment thereof longitudinally by 'the threaded elements 80.' The blocks *83 are seated upon the upper ends of suitable bushings 84 carried by the heads 12 and 13 and are held from movement longitudinally with the yokes 81 by means of suitable 'stub's'hafts 85. extending upwardly from the bushings 84 through the blocks 83 for engaging suitable clamping nuts 86 which serve to clamp the blocks upon Athe bushing. Thus, -from the` foo foregoing it will be observed that manipulation of the threaded elements causes the yokes 81'to move longitudinally and since the yokes are connected to the frames 58, the latter Will also be moved upon the tracks 61 to vary the positions of the grinding Wheels 14 and 15. The Vforegoing adjustment permits accurately positioning the grindingv surfaces of the Wheels relative to the ends of the spring bars.

In grinding spring bars of the type illustrated inV Figure 10, the Width of the grinding Wheels or the grinding surfaces is preferably substantially equal to the length of the converging end portions of the bars with the result that as the bars are moved, beneath the grinding Wheels, the latter need not necessarily be reciprocated during the grinding operation. VThe arrangement is such that as the converging end portions of the bars are moved beneath the grinding Wheels by. the conveyors, the grinding surfaces of the Wheels function to progressively chamfer the upper edges of the converging end portions. It being understoodfrom Vthe previous description that the grinding pressure is produced by the Weight ofthe wheels and associated parts as controlled bythe counterbalancing springs 73.

In the event it is desired to chamfer opposite ends of a spring bar of the type illustratedin Figure 11 having a straight end portion, rit is desirable to reciprocate the grinding Wheels so as to permit utilizing the entire grinding surfaces of the Wheels during the grinding operations and thereby effect an even Wear of the grinding surfaces. The foregoing is accomplished in the present instance by providing a shaft 99 extending longitudinally of the machine frame and centrally through suitable openings in the heads 12 and 13. The shaft 9.0 is drivenby a suitable sprocket 92 secured thereto in a position to be driven by the conveyer chain 26 carried by the stationary head 12 and the outer ends of the shaft are splined for sliding engagement with suitable Worms 93 journaled Within the heads 12 and 13. The Worms 93 are adapted to meshl with suitable Worm Wheels 94 secured to the lower ends of vertical shafts 95 which in turn are journaled Within suitable bushings 96 carried by the heads 12 and 13. The upper ends of the shafts 95 are secured to `the bushing supports 84 by means of the pins 97. Thus, from the above description it Will be apparent that during operation of the conveyor 26, the shaft 99 and shafts 95, together with the supporting bushings 84, rotate as a` unit. As shown `in Figures 6 and?, the'supporting members 84 are provided with slots 98 therein shaped to have a slidable interlocking engagement with the lower ends of the stub shafts 85. The slots 98 extend in a direction at substantially right angles to the direction of movement of the yokes 81 With the result that movementcof the stub shafts 85 and blocks 83 carried thereby Within the slots 98 will not appreciably interfere With the longitudinal adjustment of the yokes 81. YIn other Words, adjustment of the blocks 83 in the direction of the slots `98 merely causes the yokes 81 to move about their pivotal connections 82 with the frames 58. On the other hand, the arrangement is such that the yokes may be adjusted irrespective ofthe position of the blocks 83. The blocks 83 are adjusted in the direction of the slots 98 by means ofthe threaded elements 99 threadedly engaging the supporting members 84 and having the inner ends secured to the lower ends of the stub shafts 85. With the construction as thus far described, it will be apparent that when the stub shafts 85 are in axial alignment with vthe shafts 95, rotation of the latter shafts will not eifect movement of the frames 58 and as a consequence, the grinding wheels 14 and 15. Onthev other hand, if it is desired to impart a slight reciprocatory movement to the grinding Wheels 14 and 15, the adjusting elementsv 99 are merely manipulated to move the stub shafts 85 Within the slots 98 to disalignthe axes of the shafts 85 and 95. When the aforesaid parts are moved as indicated above, it will be apparent that the stub shafts 85 and blocks 83 carried thereby Will assume aposition on the supporting bushings 84 eccentrically relative to the axis of rotation of the latter bushings and since the blocks 83 are connected to the frames 58, the latter will be reciprocated in accordance with the degree of eccentricity of the stub shafts 85. It will, of course, be understood that vthe degree of reciprocation of the grinding Wheels 14 and 15 carried by the frame 58 may be accurately regulated by manipulating the adjusting elements 99.

While inl describing the present invention particular stress has been placed upon the use of the grinding edges ofy the wheels 14 and 15 to chamfer the ends of the spring bars, it will be noted from Figure 8 that the degree of angular adjustment of the cradles 46 permits moving the cradles to a position wherein the grinding faces of the Wheels may be employed for effecting the chamfer operation. Moreover, While in describing the operation of the invention reference is made to several types ofspring leaves having differently'shaped ends, it is to be noted that the machine is by no means limited to any particular shape of theend portions.

, What I claim as my invention is:

1. In a machine of the class described, the combination of a pair of relatively movable' heads carrying grinding Wheels, means carried by each of the heads for engaging opposite end portions of a bar to respectively support the latter ends in operative relation to the grinding wheels on the heads, means for moving the heads relative to each other to compensate for bars of varying length, and means for effecting relative linear movement of the bar and grinding Wheels in a direction transverse, to the direction of movement aforesaid for` grinding opposite ends of said bar. i

12. In a machine of the class described, the combination of a pair of heads mounted for sliding movement relative to each other and carrying grinding wheels, means carried by each head for engaging opposite end portions of articles to support the latter ends in operative relation to the Wheels', a conveyor also carried by each `head for engaging portions of the articles adjacent the ends thereof to move the same in a rectilinear path relative to the wheels, and means for adjustingV the heads relative to each other to vary the distance therebetween and thereby compensate for articles of diiferent lengths.

3. In a machine of the classrdescribed, the combination of a pair lof heads mounted for sliding movement relative to eachother and carrying grinding wheels, means carried .by each head for engagingl opposite end portions of articles to support the latter ends in operative relation to the Wheels, a conveyor also carried byleach head for engaging portions of vthe articles adjacent the ends thereof to move-the same in a rectilinear path relative to the wheels, means for supporting a plurality of articles to be ground in superposed relation above the conveyors for feeding the articles to the latter by gravity including a Work holding device mounted upon each head and cooperating to engage the opposite end portions of the articles.

4. In a machine of the class described, the combination with means for supporting an article to be ground, of a grinding wheel positioned to chamfer one end of the article, means for conveying a plurality of articles in operative relation to the Wheel, and means operable by said last-mentioned means for reciprocating said wheel in the direction of the axis thereof.

5. In a machine of'the class described, the combination of a pair of rotatable grinding Wheels spaced from each other to engage opposite ends of an article to be ground, means engaging opposite end portions of the article to support the latter With the opposite ends of the same in operative relation to the grinding Wheels and movable transversely to the axes of rotation of the wheels to convey the article past the grinding surfaces of the Wheels, means operated by the aforesaid means for reciprocating the grinding Wheels in the direction of their axes, and means for varying the reciprocatory movement of each Wheel independent of the other from zero to a predetermined maximum.

6. In a machine of the class described, the combination of a pair of rotatable grinding wheels spaced from each other to engage opposite ends of an article to be ground, means engaging opposite end portions of the article to support the latter with the opposite ends of the same in operative relation to the grinding wheels and movable transversely to the axes of rotation of the Wheels to convey the article past the grinding surfaces of the wheels, and means for independently reciprocating each of the grinding Wheels connected to the aforesaid means for operation thereby.

7. In a machine of the class described, the combination of a pair of spaced relatively movable supporting members carrying grinding Wheels, a conveyor carried by each supporting member for moving articles to be ground past the grinding surfaces of the wheels with the opposite end portions of the articles in operative relation to said grinding surfaces, and means for relatively moving the supporting members to compensate for articles of varying length.

8. In a machine of the class described, the

combination of a pair of spaced relatively movable supporting members carrying grinding wheels, a conveyor carried by each supporting member for moving articles to be ground past the grinding surfaces of the wheels with the opposite end portions of the articles in operative relation to said grinding surfaces, means carried by each supporting member and connected to the conveying means for operation thereby to independently reciprocate the grinding Wheels associated with the supporting members, and means for relatively moving the supporting members toward and away from each other to compensate for articles of varying lengths.

9. In a machine of the class described, the combination of a pair of spaced relatively movable supporting members carrying grinding Wheels, a conveyor carried by each supporting member for moving articles to be ground past the grinding surfaces of the Wheels with the opposite end portions of the articles in operative relation to said grinding surfaces, common means for driving both of said conveyors, and means for relatively moving the supporting members toward and away from each other to compensate for articles of varying length.

10. In a machine of the class described the combination of a pair of spaced rotatable grinding Wheels, a conveyor associated with each grinding Wheel for engaging opposite ends of an article to be ground to move the article past the grinding Wheels with the aforesaid opposite ends thereof in operative relation to the grinding surfaces of the Wheels, and means for relatively moving the grinding Wheels and associated conveyors toward and away from each other to compensate for articles 0f different length.

1l. In a machine of the class described, the combination of a pair of spaced relatively movable supporting members carrying grinding Wheels, conveyor means carried by each of the supporting members for moving an article to be ground past the grinding wheels With the opposite ends thereof in operative relation to the grinding surfaces of the Wheels, means also carried by each supporting member for independently adjusting the Wheels relative to the articles to be ground, and means for relatively moving the supporting Ymembers in directions toward and away from each other to compensate for articles of varying length.

BERT E. ROCKHOFF.

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