US2508998A

US2508998A - Camshaft grinding machine

Info

Publication number: US2508998A
Application number: US749708A
Authority: US
Inventors: Clarence J Green
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1947-05-22
Filing date: 1947-05-22
Publication date: 1950-05-23
Anticipated expiration: 1967-05-23

Description

May 23, 1950 c. J. GREEN- CAMSHAFT GRINDING MACHINE 5 Sheets-Sheet l @um @Em am u um@ WGS mmm www m gm m5 NN mh MUN @QN EN wk QEN bem Nm Nl u E NEN.

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Filed May 22, 1947 INVENToR. El. AREA/EE f l. GREEN lam BY 0M ATTURI EY May 23, 1950 Q 1 GREEN y 2,508,998

CAMSHAFT GRINDING MACHINE Filed May 22. 1947 Sheets-Sheet 2 A INVENToR.

/45 CLARENCE 1 l. GREEN May 23, 1950 Q J, GREEN 2,508,998

CAMSHAFT GRINDING MACHINE Filed May 22. 1947 3 Sheets-Sheet 3 IN VEN TOR.

HE. E 20 CLARE/VUE f l. GREEN www AT TDR/VE Y Patented May 23, 1950 CAMSHAFT er-INDING MAcHiNr Clarence Green, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corpo-:-

ration of Massachusetts application May 22, 1947, ,Serial No. 749,708

8 Claims. l

This invention relates -to grinding machines and more particularly to cam grinding machines.

@ne of the objects of this invention is to provide an apparatus and method whereby the deciencies and disadvantages which accompany present methods of cam grinding, in which grinding occurs at large or Wide variations in the surface speed .of its elements relative to the grinding line between `the cam and the grinding wheel, are relieved or overcome in a simple and eiective manner.

Another object is to provide an apparatus for changing the angular `velocity of a product cam at variable positions in its revolution in order to avoid excessive variations in the surface speed of the product cam relative to the grinding line. Another ,object is to provide a machine for varying the angular velocity o a product cam about its axis l rotation whereby the surface speed of its various elements relative to the grinding line is substantially uniform. Another object is to provide an apparatus for grinding a plurality of cam blanks on an integral camshaft at substantially uniform Work surface Speeds at the grinding line. Another object of this invention is to provide a simple and thoroughly practical apparatus for grinding a plurality of cam blanks on an integral .Camshaft Another obje/ct is to provide for the control of the rotation of a product cam that is being ground by a grinding Wheel so as to achieve substantiallyuniform, ,Surface speed of all of the elements of the product cam relative to or at the grinding line even though such elements or portions thereof are of Widely varying radii. An-

other object is to provide lmeans in a grinding machine for generating a cam surface on a cam blank at a substantially uniform grinding surface speed Over all of the portions of the cam surface.

another object of the 4invention is to provide means lor indexing van apparatus or control for changing the speedorotation ofeach ofv a succession of product Gams 0n a camshaft.

Another object .ot the invention is to provide means for automatically indexing Work speed control apparatus in timed relation with indexing of cam blanks being ground. Another Object is to finish grind a Cam lmore accurately. Another object is to obtain an improved grinding action on cer-tainv portions ofa product cani. Another object ofthe invention is to accelerate the kproduction oi ground camshafts. Another object is to achieve better and uniform grinding action on a cam periphery .even though elements or portions 0f tlienerlpherel Gam Surface are of dierent radii.

Other objects will be part obvious or in part pointed out hereinafter. The invention accordingly consists in 'the features of construction, combinations of elements and arrangements of parts, as will be exemplified in 'the structure to be hereinafter described, and the scope of the application of which will be indicated in the following clairns.

In the laccompanying drawings, in which is shown one o the various possible embodiments' of the mechanical features'of Vthis invention,

Figure 1 is a view partly in plan and partly in section showing the worktable oi a cam grinding machine, the rock bar, the Vmastercarn shaft,'the work centers,` the vwork driving mechanism and the mechanism of the present invention,

Figure 2 is an elevation of theindexing mechanism both for the lmaster cam roller'and for the electrical contact mechanism 0f the invention, the view being taken'in the direction of the arrows 2-2 or Figure l,-

Figure 3 is a vertical sectional view, on an enlarged scale, taken along the line 3-3 of Figure 1,

Figure 4 is a vertical sectional view taken along the line l-ll of Figure `2,

Figure 5 a sectional view taken along the line 5 5 of Figure 3,

Figure 61s a sectional view taken along the line 6-6 o1 Figure 3,

Figure 7 is a vieu,r partly in side elevation and partly in section of the contact device of the in'- vention together with a Wiring diagram,

Figure 8 is a diagram illustrating a cam grinding cycle.

As conducive to a clearer understanding of this invention it may at this point be noted that peripheral cams are made in Widely varying shapes and that according to known practices of grinding their cam surfaces, namely, by simply rotating the cam about its` axis at a given R. E M. to thereby present the cam surface to the grinding Wheel, many disadvantages, deficiencies, and detrimental actions and results occur. In general, the surface of a cam may be said to be `irregular even though some regular pattern of shape or curvature may be present. A simple form of cam may have a nose, flanks and a base, and I have in Figure 8 selected auch a simple orrn of cam for pulposes of illustration. The surface elements of the cam' in each of the por-- tions lie at various radial dlstance'from the center or axis of' rotationol the cam.

When their-regular surface of a cam is generated in grinding a .camblank according to known: practices, the cam. is; rotated about its axis at. fixed or Constant .Speed and a result tlf-lesurface speeds of the various portions of the cam. as they are successively presented to the grinding wheel, vary widely relative to the grinding line, the line of Contact between the grinding wheel and the cam. Thus, when the cam turns at a constant angular velocity, the flanks of the cam sweep past the grinding line at a much faster speed that the nose. and the base moves at an intermediate speed in surface feet per minute.

This varying surface speed of the nose, flanks and base of the cam relative to the grinding line for a constant turning speed of the cam in revolutions per minute is graphically illustrated in Figure 8, where a typical cam 20 and a grinding wheel having a grinding surface 2| are shown in various relative positions in mutual contact at a grinding line as the cam is revolved relative to the wheel to grind it. The illustrative cam 20 has a major center O through which the axis of its revolution passes. a base 23 with a radius of one inch about the center O, straight danke 2d and 25 each seven-eighths of an inch in surface length, and a nose 25 with a radius of one-hair inch about a. minor center 26a which is materially displaced from the cam axis. The surfaces of the

flanks

24 and 25 are tangent to the surfaces of the base 23 and the nose 2B.

To grind the flank 24, the cam 20 and grinding wheel 2! may be brought in contact to form a grinding line at 21 with the grinding wheel center at 28 relative to the cam 20. AS the cam is rotated counterclockwise, the grinding line moves along the flank 24 seven eighths of an inch to grind the flank whereupon the grinding line is now at 29 and the relative position of the wheel center is at 3Q. This change in relative positions of cam and wheel is effected by cam rotation about the center through the angle AOB which is 16 degrees to grind the flank 24. During cam rotation to grind the fiank the grinding line moves from 2l to 29, a surface distance of .054 inch per degree of cam rotation.

To grind the nose 25 the cam continues to rotate counterclockwise about its center 25a so that the grinding line moves along the surface of the nose 23 to 3l. a distance of 1.08 inches, the wheel center now being at 32. This change in relative positions of cam and wheel is effected by cam rotation about the center D through the angle BOC which is a cam rotation of .'l?. degrees to grind the nose 26. During cam rotation to grind the nose the grinding line moved along the surface from 29 to 3| a surface distance of .Oli inch per degree of cam rotation. as compared to .054 inch per degree for the flank. To grind the flank 25 the cam continues to rotate counterclockwise through the angle COD about its center U causing the grinding line to movel along the flank 25 at a rate of .054 inch per degree ci cam rotation. The grinding line is now at 33 and the wheel center at 34.

To grind the base 23 the cam moves counterclockwise about its center 0 and the grinding line moves from 33 to 21. the wheel center now being at 28 where it started. This change in relative cam and wheel positions is effected bv cam rotation about the center U through the large angle DOA which is a cam rotation of 23S degrees to grind the base. During cam rotation to grind the base the grinding line moved relative to the base 23 from 33 to 2l, at a rate o1' .01'7 inch per degree of cam rotation. The ratio of the surface speeds for the anks. nose and base of this cam for any constant angular velocity is therefore 54:11:17.

Assuming that the cam of the illustration is rotated at twenty revolutions per minute, the grinding line moves, relative to the nose surface at a surface speed of 79.2 inches per minute, relative to the base surface at a surface speed of 122.4- inches per minute, and relative to the anks at a surface speed of 388.8 inches per minute.

The disadvantages of grinding at these tremendously Varying work surface speeds as has been the past practice are readily apparent when it is pointed out that the rate at which the grinding wheel may be fed into the work depends directly upon the surface speed of the revolving work piece relative to the grinding line, and the rate of wheel feed into the work governs the time of the overall grinding operation. For a given operation, it is desirable that the rates of wheel infeed and work surface speed bear certain relations and they are established in order to obtain the most efficient work removal. However, to grind a cam, which always has a number of different surface speeds for a constant angular velocity, the maximum constant angular velocity which can be given the cam is the one which will give the work surface speed required at the grinding line for that portion of the cam which has the greatest surface speed for any given angular velocity. Then the other portions of the cam have surface speeds at the grinding line which are too slow for eiiicient grinding operation. For the cam illustratively dimensioned as above, it was shown above that at twenty revolutions per minute the surface speed of the flank is 388.8 inches per minute. If this is established as an efiicient work surface speed at which to grind the cam for a given rate of wheel infeed, then the resulting surface speeds of 79.2 inches per minute for the nose and 122.4 inches per minute for the base are not efficient work Surface speeds for grinding these parts. The finish produced around the cam is not uniform, resulting in the necessity of further lapping and nishing operations. Considerabletime is wasted in turning the work too slowly for certain portions of the cam because the grinding wheel is not removing as much material as it eiiiciently could on those portions of the cam.

Referring now to Figure l, the machine illustrated is a cam grinder for grinding the many cams on an automotive cam shaft. The present invention is fully applicable to an automatic cam rinder in which the work table 53 is automatically moved from station to station successively to cause the grinding wheel 21a to grind the cams 23a. 2M), 20c, Zild, 20e, 201. 20o and 20h. Before such movements, known as indexing, the rock bar of the machine is swung to move the cam shaft having the cams 20a, 2Gb, etc. away from the grinding wheel 21a andat the same time to move the master cam shaft 54 away from the master cam roller 55: coincidentally the grinding wheel Zia is retracted so that it can be advanced in feeding components to grind the next cam such as 29h. The table traversing mechanism of an automatic cam grinder, the wheel retracting and feeding mechanism of such grinder, and the fluid connections to cause the rock bar 52 to swing away are now well known in this art and therefore will not be described herein. For an understanding thereof reference may be had to U. S. patent to Belden and Silven. No. 2,022,178 and. U. S. patent to Silven, No. 2,078,463. There will be described herein only so much of the structure of such old automatic cam grinder as will sufi-ice to show the connection of the invention therewith.

accepts eerring `now-to Figure -3,thetab1eorfcarriege 50 1*basa-flat yway 60 and xV-vvays '6| which rest on aidait way 52 "and 'V-Ways-63 V-providedhy the vhase 6'4 of the machine. Referring to Figure A1, near the fiet hand lendof the'carriage -50 is :shown Aa bearing 'boxes which is `fastened to `the carriage 50and journals Vone endof the rock bar 52; the other end of the rockba-r 52 is beyond the right hand end of 'Figure A1 'but in Figure 3 a similar journal box i5? is show-n, which is likewise 'iastened to ith-e lcarriage 50, and which journals the righthandzor far 'end of the rock bar 52,-a1trun nion portionil 'of whichis locatedin-said journal box V`|`| :ari'dis shown in Figure I3 in ydotted lines.

"The -rock bar 52 V`has upstanding portions 10, 'Il and ''i'2 which house 'bearings "13, 'i4 Vand 1 5 journalling the master Vcam ,shaft ,54. Previous cam .grinders have had master cam shafts "but thismaster cam .shaft 5'4 isof'extra'length tosupport Anot only themastercams'a, 85h, Sdcgd, ejf, 56g, and 30h ,but also a.set of control cams 50a, 90b, "Sc, Bild, 50e, '90?, 90g Yand liih. These contro1.cams `time to 99h are ,part .of the mechanism of the present invention.

The cams '806g Stb, etc. are master vcams to generate the shapes `of the product cams "2M, 20h, etc. 'The master -cams Ltda, Stb, etc. Aare keyed to Ythe cam `shaft 154 and held betweenan enlarged `portion 9| .of the `cam shaft 54 .and a sleeve 192 .on said shaft which is heldinposition byanutlt on-a threaded portion 94o'f the masteroamshaftrld. The ycontrol cams I9 da, etc. are likewisekeyed to the camshaft and are ,held between a shoulder ..95 4and a Y,sleeve ,Q1 .backed upbya `nut 98 onthe threaded portion .S9 of :the cam shaitfi. .This cam shaftt ,isconnected tio-fa .universal joint `i di? which v is connected .by .a shaft vtoanother .universal joint .|52 .which isiconnected tovashaft 3 mountedin abealiing housing .tiiastened to the table 5d, the Shaft Lfhavingmountedon its left hand. end a pulleyxl which-is-connected bybelts AH rt0 /puliey |01 driven byian electric motor m3 through a reduction :gearing Ain a casing |09. A .master camshaft is ithus. rotated at a -speed `determined byrthespeed of the motor |08 .and .the drive is continuous despite Ythe vi act that Ithe, master -,cam shaft 54 4oscillates .aboutthe .center .of voscillation ofitherock bar 52.

`:The .fmaster 1 cam shaft '54 -is also a work :drive shaft. fStill referring Ato Figure `l, adjacent-the right;hand :bearing 'Eis an ,enlarged portion of the master cam shaft 5 which operates as a thrusti'member. The -masterqcam shaft-54.11% a conical axial holegnot shown, in its fright hand end-.which receiveda work z holding center |3 which acenters Ythe i `

cam shaft

1,53; zthe other end ofi-thecam shaft'rgis-centeredffby a .taili center i124 'rheld by a :tail: stock if t5, that vv:adiustablav fastened tolthe` rock bar 52. Thuszthe-workpieee eamishaftfdi is held for rotation inline-With the mastery camfsha'fti'd and it :is'rrotated' through :a drivingzdog H25 which Vi'hasna :pin I| Il enteringa Slot f in a driving head I8 lfastened :to :the :right handerfd Aof 'the master. cam shaft*` 54.

Ati anyf ltime duringfactual grinding the. master cam:ro'ller"55 is'iny contact Awith one: offthemasterrcams. "It is shownfas'fbeing:infcontactwith master-cam `80a iwhile' the grinding v.

wheel

1,2 Iza isv'gri-ndingfthe productfcam 20a. Thefrollerr can rotate .and it is indexed `from ltime fto f time tojplace it adjacent the 1 various cams 80a, F8015, 80e, etc., 'and elik-ewise tis carried by f the table libutfotherwise vit doesnot move. Thus it iis the-rotationoffa mastery vcam suchfasliilla` inA coniii 6 tact with -the master :cam'roller 55 l-wl'iioh oscil lates Athe master :cam vshaft 54 on the pivotal center of `the `rock ba-r 52, the tail center |:I4 Yas well aas A`the iheadcenter I3 likewise oscillating. This `is -What-generates the desiredshape on ythe product 'cams "20a, 20b, etc.

iWhen :the `product cam '20a has lbeen yground, the machine'by mechanism-not herein described, causesthe table or carriage 50 tofrnove vto place the product fcam f20b in front `of the lgrinding wheel v2|;a. Just prior to lthis movement ythe rock bar A52 isswung tomove the product cam shaft 53 away Afrom the grinding Wheel 2|a'and to move themaster cams away from the master cam roller ,55. YThis motion oft-he table or 'carriage l150 automatically causes -the master cam roller 55 to bemoved opposite to'the next master cam 8012, and gthis mechanism lwill now'be described.

Referring now to'Figure 11,' the table or carriage 50 'hasan upwardly extending support -|25 ,which has the shape of a rectangular parallelopiped. IniFigure 1 the upperframeportions and mechanisms'have been. omitted for thesake of clarity; if they Were shown ,the master cam shaft 54 and the variousmaster camsBiia, jb, etc. and d, 90b, etc. Vand also other parts wouldbe obscured. The .Support |125has.a number of tappedholejs |26by means of which anoverarm l|2`| is bolted tothe support 1.2.5. As shown inFigure3 this overarm |27 extends overithetop of therock bar L52. and over .thel master camshaftj and as willbe seenby a comparison of FiguresZ andj3 the-:over arm `|2,'| has `a .flat v,horizontal portion |2B4forming a complete cover for the v cams 80d, 80147, etc., the horizontal portion |28 being connetedtolarge ribs |29 and .|.30.in`paral1e1 vertical planes which extend well above the hori- Zontal portion `|28vand which ribs |29 and |30 merge into `downwardly extendingarzns |3| and |,32at the rear side-of the table.

-Still referring tojr'igure 2,extending horizontally 4iromthe rightphand side. of the arm |32 is an'integrallportion |33 which, as bestlshown in Figure l,V is T-shaped-in cross section. The down- Ward 1yextending.arm |3| `supports a journal |;35,ithe:downwardly extending armi 32 supports ac-iournal |36 (Figurefi) and adownwardlyextending arm |31 on theend-of .the :portion v|33 supportsajournal |38. .These journals |35, |313 and |238 as best shown in Figure 1 support a shaft |-4.0;141pon whichthef,master cam roller .55 is mounted. While the shaft |40 could be ,a nQn-jrotatablehaft it hasbeen; found preferable togkcy;theyro1ler;55=to -it asfbymeans oiga long key L42 so :that rthe shaft |40 rotates in journals which-,are :widely separated.

'.Refer-ringxnowitc Figure `1,1:fastened to-andy .eX- tendingirearwardly 5 from i the ibase sali isean arm Orl'the end of which. is` a; bracket 1 4,5, holding and supporting a pairqof bars |41, |41. Referring to Eignres ,..1,z2iand;;3,; at thelower. ends of v.the downwardly'.extendingfarms |'3|,;|32 and'|3l' are sliding Ysupports A50, .|5I .and |52 respectively Which'fmove withthe table -orfcarriage' butat all l'.tirries-:support .the bars t4? from sagging. Supported'by the bars.|.4| are dogs |55,v secured inl-adjusted positions by -means of-screws |56. These dogsr |55.shou1d bezspaced'the same as the spacing` of '.thepro'duct cams 20a, 2019,;200, etc. Sinceithe bars |41 'areheld by ithe arm |45fsecur-edi to thebaseli, thedogs |55 "do not move; asfthe table orcarriage 50 moves `from one position to another a "clog .4.55 is :engagedvby :a :star wheel i |58 1XWhich 1 moves `with fthe. table i 01u-car,

riage 50. Each such engagement therefore rotates the star wheel |58 through a unit angle.

Referring now to Figure 1 in connection with Figure 4, a yoke member |00 straddles the roller 55 and rests upon the hub |0| thereof and encircles the hub half way as shown in Figure 4. A semi-circular portion of the yoke member |90 is on each side of the roller 55 and thus the roller 55 is moved whenever the yoke member is moved parallel to the shaft |40. A rearwardly extending portion |95 of the yoke member |90 has a depending portion |95 which is secured to the rack |80 which, as shown, can move only parallel to the shaft |40. Thus indexing movements of the rack |80 responsive to actuation of the star wheel |58 cause indexing movements of the cam roller 55.

Referring now to Figures 1 and 3, attached to the rack |82 is a rearwardly extending portion |99 of a yoke 200 which extends half way around the shaft |40 between the bearings |35 and |38. This yoke 200 is therefore moved along the shaft |40 whenever the star wheel |58 is turned through a unit angle. Such movement, being step by step in response to step llcy step motion of the table 50, is referred to as indexing and it will be noted that the yoke 200 is indexed shorter distances than the yoke |00 due to the difference in diameter between the gears |18 and |10, thus to allow for the closer packing of the cams 98a, 90b, etc., than that of the cams 80a, 80D, etc.

The yoke 205 has a pair of depending parallel portions 20| between which at all times is a finger 202 extending rearwardly from the hub 203 of an arm 235. The hub 203 is keyed to a trunnion shaft 2 0 by means of a key 2| I, Figure 5, and the shaft E! 0 as shown in Figures 3 and 5 is mounted in bearings 2|2 and 2|3 in integral arms 2|4 and 2|5 extending rearwardly from the rock bar 52.

Thus whenever the rack |82 moves, the yoke 208 must move with it and, since the nger 202 is always between the depending portions 20| o1 the yoke 200, and since the nger 202 is integral with the hub 203 of the arm 205, the arm 205 will be moved whenever the rack 02 is moved. Thus the arm 285 is indexed from control cam to control cam, e. g. from cam 96a to cam 98h and then from cam 90b to cam 50c and so forth.

Referring now to Figure 5 and noting the section line for this gure on Figure 3, the shaft 2 I0 has on one end a holdin-g collar 2|6 and on the other end a hub 2 I8 with a split arm 220, the hub 2|8 being keyed to the shaft 2|0 by means of a key 22|. The collar 2|6 and the hub 2|8 keep the shaft 2|0 from moving axially. Referring t0 Figures 3 and 5 a long bolt 225 extends through the rock bar 52 and through the split arm 220 and acts an adjustable limiting stop to prevent the arm 205 from moving clockwise, Figure 3, relative to the bearings 2 2 and 2 I3 in which its trunnion shaft is journalled. A nut 225 on one end of the bolt 225 and a pair of nuts 221 on the other end thereof set the adjustable limit while a spring 228 on the bolt 225 resiliently keeps the arm 205 at the limit angularly.

During the grinding operation a master cam such as the cam a stays in Contact with the master cam roller 55. Therefore the rock bar 52 oscillates. The force which keeps the master cam such as 80a in contact with the master cam' roller 55 is derived from a spring 230 (Figure 3) in a cylinder 23|, the spring exerting its force against a piston 232 in the cylinder 23 the piston 232 being attached to a piston rod 233 which extends outside of the cylinder 23| and has on the end thereof a clevis 234 by means of which it is pivotally attached to an arm 235 which is integral with the rock bar 52. The cylinder 23| is positioned by means of a split collar 236 which is pivotally mounted on the overarm |21 so that it can swing to accommodate the slight angular motion of the piston rod 233. Whenever the table 50 is about to be indexed, fluid is admitted to the upper side of the piston 232 in the cylinder 23| which rocks the rock bar 52 carrying the

cams

80a, 80h, etc., away from the master cam roller 55 so that the master cam roller` can be indexed without hitting one of the cams on the side. The means for causingiluid to be admitted to the cylinder 23| at such stages is no part of the present invention having been described in the aforesaid patents and being otherwise known to the art.

This rocking of the rock bar 52 to carry the cams 88a, etc. well away from the master cam roller 55 likewise causes the arm 205 to move relative to its assembly on the rock bar 52. The finger 202 strikes the shaft |49 and this swings the arm 205 counter clockwise relative t0 the rock bar 52, compressing the spring 228. Of course it will be seen that since the rock bar is moved clockwise (Figure 3) it is really the rock bar and associated parts which move away from the 'arm 205, but relatively speaking the arm 205 moves counter clockwise. At other times the arm 205 has a fixed angular relation to the rock bar 52 and the parts assembled thereon. This relative counter clockwise movement of the arm 205 permits said arm and the electrical mechanism associated therewith to be indexed from one cam 90 to another cam 90 without interference,

The arm 205 carries electrical contact mechanism which controls the speed of the motor |08. Referring now to Figure 1, the arm 205 has a pair of rigid

parallel projections

240 and 24|.

vof the cams 9lla 91111,x etc.

Through the projectionlllf. is a boref242f in which is, slidably mounted a rod. 2431. having. a-v narrow contact portion: 24.4 which can engage any one The rod. 2113- is keyed by means; of a-` key.- 2-45 to. the rigid parallelz projectioni Md so; that. the, narrow contact portion willv not get out oi alignment. The rod. 243 has an enlargement, 2.1!3` between which and.. theA rigid parallel, projection 24.!)k extends a spring`v 2,49. It Willinowbe seen that as a-.eam 9i) rotatesit moves the.v rod 2.43. tot differentpositions relative to the projection 240, and.` the projection. 241,.`

' Still referring to Eigure. 7, at the lett hand en d of: the. rod 243l is a.v screw threaded portion 250 upon.. which is screwed an insulating sleeve. 25! firmly located in. abor.e. 252; of a. metal can` 25:3. Around theA capz isa. metalcollar 2514 having an ntegral'contact` arm 25.5.v Into the collar 254` is screwed al binding post screw 25S. on which is a terminal. member 25.1. between binding post nuts 2.53@v The terminal member 252'` is on the end. of a wire. 25B.,

The. arm. 255,'. makes and. breaks contact with a long binding post screw 2.5i. on which. is a. terminalmember ZSZbetWeenbinding post nuts 26.3. This binding post. screw 25|.v is ad'iustabl'y positioned in a.l threaded' sleeve ''.iby means of` a nut 256.; Thev threaded sleeve. 2652 has'an integralv ring ZET which. locks it t'o an integral insulating sleeve 26H which is moldedaronnd the sleeve 2:35 which may be made of' metall The insulating sleeve 26:8 is secured in thel projection 241i" by means of externally threaded ringsy 21e. screwed into a cll'neaded'y borel Z'Hj inthe projection 24U.

The. motor I'SS is a variable speed motor, for example i't can be a direct current motor. It is represented in Figure r{"as having two brushes 215 and 216'. The brush 22,5' is connected to a main power line 2,11.. The brush 21'5 is connected lby aline. 218' to a rheostat' coil' 2853; Ay movable rheostat contact 281' is connected to a wire 282 on the end of' which is the terminal member 262.

'The wire, 250; is connected to a hand' switch 283 which is used' to stop and start the motor IU8. The other sirleof the hand switch 283 is connected to the other maink power line' 2'85". Thus when the`- larm 2'55` is in Contact with the binding post screw' 2M, the motor m8' will` run at a speed determined bv'the position of the movable rheostat contact 2812 The cap 2'53 hasa terminal' point 28T which can Contact a: terminal point 223i? of a metal' rod 28.9 which is' sii'd'able in an insulating sleeve 250 moi'd'ed inside of'a metal.' sleeve' 291' which' has an interlocking ringl portion 292. The metal sleeve 29V isv externally threaded andY screwed into` a threaded bore 29'4 in the rigid parallel projection 21M. A nut 2% on the threaded sleeve' 29"! adjiistabzly secures the latten in the` pro'iectio-n 2M. The rod 269 has an enlarrned portion 299 and a spring Stil on theY rod 289 extends between the enlarged iiiortionv 299 and the insulating sleeve 29D.

n The rod 239 on the' left hand end' has a threaded binding post portion 3i!! on whichr is a. terminal member 3%2 between nuts( and 304'. The spring 361.0' urges the rod 2-89to the right to aposition; determined by the nut 3534 and of course the nutsA 303v and 3M can be4 adjustedl thus to adjust the normal position ofthe rod 2555 in the' sleeve 2:93" and-` f'urtlrerm-orev the position oi the sleeve 2&1! can' be adjusted by loosening the nut 295, turning.- the sleeve- 291 and" then re-t'igl'iteningy the lnut 285i'. The terminal member 302' is on' they end "of a wire 306 which is connected to a movable rhx'eostati` conta-ct 3021. It will now be seen that When the

terminal point

278,1 is in contact. with the terminali point 2.88,.the motor |03'. willi run. at aspeed dependent uponlthe position. of. theme11',- able rheostat contact 3111. It will` further be seen that when the point 28T hascontacted". the point 2831 further. movementA to the left of the point 238,1l will not break. anything but will simply crush the, spring, SDU.

I provide a. third movable rheostat contactjvll connected by a Wire 3`|`| to a junction 312

withithe wire

2,60. When the arm 2 55isnot in contact with the binding postv screw 261, andthe point 28.1 is not in contact withthepoint 288,. the motor |.0`8 Will' run at a speedl determined by the movable rheost'at contact Sflil.. Thusv three speeds are established for thefmotor. Ill-8' and each of' them' can be easily. adjusted'.

All of the cams 9.01 have a base portion 910x, flank portions 99h; anda nose 90e., The adjustaf ble electric contact, mechanism is. set sothat when the contact. portion. 214 is opposite the base Silit,l there will be a slight clearance and therefore the arm 2.55 will bein. contact with the binding post 26|..` But whenv a flank? 90'11- is ad- J'ent the contact portion 24l4the rod 243 is. positifoned to thev left breaking contactbetweenthe arm 2155 and. the binding. post 26|... Furthenmore, contact. between. the. points. 28,1. and 288iis made and. kept while. theA contact portion 2Mg is in engagement with, any partl of the nose a.v

It will now heA seen. that. the product cam shaft 5.3- willv be rotated. at diierent angular velocities during, each revolution, thatis toA say at one anguiar velocity when the. base 23 of a, cam 20 is in. contact with the grinding wheel. 21a, at another angular velocity when either ofV the.

ilanl'rs

24 or 25 isiincontactwith the` grinding wheel lila, and ata third angular velocity when the` nosel 26 is in contact with^ they grinding wheel Zia. rEhe base alla: of the cams 90. should displacei ther same angle as. the. basey 23 of the corresponding cam 2.0 and similarly tor thea-nk-s andthe nose. Because ot the fact that the armature of the motor L98 andl allg the other moving parts have) inertia, the cams- 9.0l should be timed a little. aheadof, the product cams 20. ThisV advance in timing can be arbitrarily setatabout 4 with goed practical resultsz Ii, as is. sometimes the. ease, the various cams 2t)di1ferv considerablyy from each other, the machine nevertheless will perform.y accuratelyY because the cams.- Sillcan be made. correspondingly different.v

Theg movable rheostat-contacts 281, 3.01,- and 31,0 should. beV set to. give: constant` surface speeds" tor the: flanks-nose andbase ot the product cams 20 relative to. the. grinding line and. may readilybe so set as will now be apparent. The. circuit through the wire 3io` will ger-ierally be,- adjusted to. havey the. greatest resistancev and thus when either ot the other circuits is closed itv will control theI speed.. Adjustment can readily be made ofthe contacts 28.5. and` 3,81 to allow for the fact that some current will ow through. they circnit including` thel wire 3 l-IV which has the highest-resistance All adjustments canv be made by the application of Ohms law. and mathematics.

The drawing-s, show ay resistanceY coill 280 but this is. merely because it is conventional inpatient drawings and a bar resistor canbe used or any other device to.. vary the speed off. the. motor IM can be used'. The motor L08 can beV any typeV of variable speed electric motor, not. necessarily a direct current motor.

It will thus be seen that. there has. been` provided. by this invention armaratusI in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinabove set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a cam grinder, the combination with a table or carriage, journals for a rock bar on said table or carriage, a rock bar in said journals whereby said rock bar can be oscillated on an axis extending through said journals, work centering and driving mechanism on said rock bar located away from said axis whereby as the rock bar oscillates the work centering and driving mechanism will move through an arc, a master cam shaft having a plurality of master cams mounted for rotation on said rock bar also away from said axis, a master cam roller mounted on said table or carriage adjacent the master cam shaft whereby it can contact one (at a given time) master cam to control the oscillations of said rock bar, means exerting a force on said rock bar to keep the master cam in contact with the master cam roller, means to index said master cam roller from one master cam to another one, and power means connected synchronously to drive the work driving mechanism and the master cam shaft, of a control cam shaft journalled for rotation on said rock bar having a plurality of control cams thereon, connections to the power means to drive the control cam shaft synchronously with the work driving mechanism and the master cam shaft, make and break electrical contacts mounted on said rock bar and having a part to be moved by one (at a given time) of said control cams, means for moving said make and break electrical contacts away from said control shaft to permit indexing, means mounting said make and break electrical contacts for indexing from one to another of said control cams, and means to effect said indexing of said make and break electrical contacts when they are moved away from said control shaft.

2. In a cam grinder as claimed in claim 1, the combination with the parts and features therein specified, of a shaft on the rock bar parallel to the axis of the rock bar, said make and break electrical contacts being mounted on said shaft on the rock bar whereby they can be swung away from the control cam shaft on said shaft on the rock bar as a pivot and can be slid on said shaft on the rock bar to index from one control cam to another.

3. In a cam grinder as claimed in claim 2, the combination with the parts and features therein specified, of an arm and connections for swinging the make and break electrical contacts on the shaft on the rock bar responsive to an oscillation of the rock bar.

4. In a cam grinder the combination with a table or carriage, journals for a rock bar on said table or carriage, a rock bar in said journals, whereby said rock bar can be oscillated on an axis extending through said journals, work centering and driving mechanism on said rock bar located away from said axis whereby as the rock bar oscillates the work centering and driving mechanism will move through an arc, a master camshaft having a plurality of master cams mounted for rotation on said rock bar also away from said axis, a master cam roller mounted on said table or carriage adjacent the master camshaft whereby it can contact one (at a given time) master cam to control the oscillations of said rock bar, means exerting a force on said rock bar to keep the master cam in contact with the master cam roller, means to index said master cam roller from one master cam to another one, and an electric motor connected synchronously to drive the working driving mechanism and the master camshaft, of a control camshaft having a plurality of control cams thereon, an operative connection between said control camshaft and said electric motor whereby said control camshaft is rotated synchronously with the master camshaft and the work driving mechanism, control mechanism including a variable impedence to change the rate at which said electric motor rotates the work driving mechanism the master camshaft and the control camshaft, part of said control mechanism being positioned to be operated by one (at a given time) of said control cams, whereby said work driving mechanism will have at least two speeds during a single revolution thereof, and means to index said part of said control mechanism from one control cam to another control cam, said two indexing means being synchronized.

5. In a cam grinder as claimed in claim 4, the combination with the parts and features therein specified, of the further feature that the control mechanism also includes make and break electrical contacts.

6. In a cam grinder as claimed in claim 5, the combination with the parts and features therein specified, of means for swinging said part of said control mechanism away from a control cam just prior to the indexing and to return it to the new control cam when the indexing is accomplished.

7. In a cam grinder the combination with a table or carriage, journals for a rock bar on said table or carriage, a rock bar in said journals whereby said rock bar can be oscillated on an axis extending through said journals, work centering and driving mechanism on said rock bar located away from said axis whereby as the rock bar oscillates the work centering and driving me-chanism will move through an arc, a master cam shaft having a plurality of master cams mounted for rotation on said rock bar also away from said axis, a master cam roller mounted on said table or carriage adjacent the master cam shaft whereby it can contact one (at a given time) master cam to control the oscillations of said rock bar, means exerting a force on said rock bar to keep the master cam in contact with the master cam roller, means to index said master cam roller from one master cam to another one, and power means connected synchronously to drive the work driving mechanism and the master cam shaft, of a control cam shaft having a plurality of control cams thereon, an operative connection between said control cam shaft and said power means whereby said control cam shaft is rotated synchronously with the master cam shaft and the work driving mechanism, control mechanism to change the rate at which said power means rotates the work driving mechanism the master cam shaft and the control cam shaft, part of said control mechanism being positioned to be operated by one (at a given time) of said control cams, whereby said work driving mechanism will have at least two speeds during a single revolution thereof, means to index said part of said control mechanism from one control cam to another control cam, said two indexing means being synchronized, and means for swinging said part of 13 said control mechanism away from a control cam just prior to the indexing and to return it to the new control cam when the indexing is accomplished.

,8. In a cam grinder the combination with a table or carriage, journals for a rock bar on said table or carriage, a rock bar in said journals whereby said rock bar can be oscillated on an axis extending through said journals, work centering and driving mechanism on said rock bar located away from said axis whereby as the rock bar oscillates the work centering and driving mechanism will move through an arc, a master cam shaft having a plurality of master cams mounted for rotation on said rock bar also away from said axis, a master cam roller mounted on said table or carriage adjacent the master cam shaft whereby it can contact one (at a given time) master cam to control the oscillations of said rock bar, means exerting a force on said rock bar to keep the master cam in contact with the master cam roller, means to index said master cam roller from one master cam to another one, and an electric motor connected synchronously to drive the work driving mechanism and the master cam shaft, of a control cam shaft having a plurality of control cams thereon, an operative connection between said control cam shaft and said electric motor whereby said control cam shaft is rotated synchronously with the master cam shaft and the Work driving mechanism, control mechanism including a variable impedance to change the rate at which said electric motor rotates the work driving mechanism the master cam shaft and the control cam shaft, part of said control mechanism being positioned to be operated by one (at a given time) of said control cams, whereby said work driving mechanism will have at least two speeds during a single revolution thereof, means to index said part of said control mechanism from one control cam to another control cam, said two ndexing means being synchronized, and means for swinging said part of said control mechanism away from a control cam just prior to the indexing and to return it to the new control cam when the indexing is accomplished.

CLARENCE J. GREEN.

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

UNITED STATES PATENTS Number Name Date 1,228,418 Eaton June 5, 1917 1,879,506 Roberts Sept. 27, 1932 1,914,561 Fraser June 20, 1933 2,060,437 Harley Nov. 10, 1936 FOREIGN PATENTS Number Country Date 643,632 Germany Apr. 13, 1937