US1937999A - Camshaft grinding machine - Google Patents

Description

Dec. 5, 1933. 1'. c. VAN DEGRIFT ET AL CAMSHAFT GRINDING MACHINE Filed Ocf,a 26, 1928 Sheets-Sheet 1 ln/ventola 6.27% zi f -Dec.5,1933. T. c. VAN DEGRIFT Er AL 1,937,999

CAMSHAFT GRINDING MACHINE Filed Oct. 26, 1928 4 Sheets-Sheet 2 a? d W' flammig Dec. 5, 1933. T. c. VAN DEGRIFT E1- AL 1,937,999

CAMS HAFT GRINDING MACHINE Filed Oct. 26, 1928 4 Sheets-Sheet 3 5, 1933. T. c. VAN DEGRIFT Er AL 1,937,999

CAMSHAFT GRINDING MACHINE Filed Oct. 26, 1928 4 Sheets-Sheet 4 Paal-iisd Dec. 5, 1933 UNi'ra-T STATES il l 1,937,999'

PATE-N1" FFlcE; f

" VGaiuspara?Germanic, MACHINE l v Thomas C; Van

Claims.

This invention relates -to pattern` controlled machines for-forming a given surfacefcontour on camsfor other non-round objects. A

bjects of Vthe invention are to` reduce, -in the 5 replicagV errors that may unavoidably exist in ther pattern; to translate the lift of the patterninto a right line relative moyementof tool and rworkY causing .relative movement oftool and blank for the purpose of removing or displacing material of theablank, and means for imparting other relative movements of tool and blank for the pur- -pose of producing a precalculated contour. In i :application to the specific uses contemplated he blank holding means is rotated withrespect to the tool to effect removal or displacement of material andthe tool is given an in and out movement with respect to the blank by a rotating Ypattern of .which the object to be producedV relatively smallA replica. The pattern is rotated at'the-same angular speed as the blank and the ertent'o movement impartedY by the pat-ternr o-to tbetool is'reriuced proportionately to the precaiculated dimensions or" the iinishedobject with respect-to thoselof the pattern.

Theinvention comprises also Various subcom-A binations 'and elemental details specificallyv dez ibed hereinaiterand-illustrated in the accompanying drawings in which:

i is a front elevation of a complete ma-V chine; 4 i

Fig. 2 is a plan view; j.: iiig-is an end elevation viewed oi Eigs. 1 and 2; p Y

fromthe right ll is ahorizontal section of a fragment ofV themachine taken along-line 4 4 of Fig. 3;

Fig..5 is a section on line 5 5 of Fig. 4; Figc is an elevation oi 'a rotary tool and its carrier mechanism; Viewed from the left Vof Figs. 1 and 2; Y V g 1 Fig. 7 is an'elevafion of the rotarytooland its carrier mechanism partly in section Viewed from the iro-nt; f

Fig. 8 is a detail View `ci the main operating lever ofV the tool carrier, viewed from'the front; Fig. 9 is a detail View inside elevation of the tool carrier supporting bracket and tool` guard;

le is a detail in front elevationvof the supporting bracket shownfin Fig. 9;

Figlli is a'section exposing .the live center and secured to the workpiece, and v v Fig. 13 is alsectional detail of arotating Dgriftv ami William H. McCoy;

Detroit, liich.- :1

pplication October.Y 26,

192e. sei-iai No. 315,200 (Cl. 51m-101) ing tool, arbor and bearings. f. l

W e havev` illustrated 'our invention as embodied a machine for grinding to a precalculated contour the valve operating cams of an internal combustion engine of the four-.strokecycle,A poppet- -valve type.'

scribed eomprisesmeans for supporting land ro-A tating a work piece` or blank to be shapedy in con-.- tact with a'tool, and means for supportingY and. imparting to -thetool movements properly timedv The -machineillustrated and-1de,V

and directed to shape thework piece'into a nished product of precalculated contour andV dimensions.A

In Figs. 1,A 2 and 3 the workpiece,orfblankgsupporting base is indicated by numeral 2,0..A A tool supporting base 21 is arranged rearward-tof the work supporting base. Brackets 22 and-75 for supporting members are connectedto the `base 21 and. a

bracket23 for a similarpurpose is connectedto,

thebase 20. YA pedestal 24 supports amotor 78 for rotating the workpiece and moving the tool toward and from theaxis of ,the Work by means Y to be described.

. Theupper surface of base 20 is provided'with bearingsV for certain transmission the usual ways for supporting a work table'25`,. i which may be adjusted longitudinally .by alead r screw or other usual mechanism (not shown) u operated by a hand Awheel 26 as is common in. machine tools. On the table 25 are ahead stock 27 and a tail stock 28, ,'.bothof which maybey ad justed longitudinally of the table accordingtovv the length of the workpiece to be held'between them and locked inl adjusted position'bybo-lts 29.

Y having T heads engaging an undercut'groove 30 in the table as .is customary in analogous AIna-Y chines.

. the head stock 27. Shaft 35 is slidable in and through vbearings in the bracket 23. Shaft 35 .also slides freely through a'bevel pinion 36, which is keyed tothe shaft and is in mesh with a driving gear on a transmission Atrain lto be described presently.

In order that the Work piece 33 maybe rotated by the shaft 35 and work driving lug 34, a dog 37 in the form of a short tubular body having in one face a plurality of notches 38 shaped to interlock .with the work drivingrlug 34 is secured to theend of the vwork, pieceadjacent the live` Live center 32 and worku Thus the-head stock may be adjusted' without disturbing the power connections forro# Y Jtating the Vwork piece.

The tail stock is equipped with the usual 1 adjustable dead center point 31 and thexhe'ad ,ward overhanging portion 54.

center as by a set screw 39. The work piece shown in Fig. 2 is a valve-operating cam shaft for a six cylinder automobile engine. As some of the cams are angularly displaced with respect to others and the relative movements of work piece and tool remain the same, it is necessary to index the work piece after the cam or cams having one angular position have been iinished in order to bring it to the proper position for succeeding operations on a cam or cams having dierent angular position. The notches 38 in the dog 37 are so spaced as to enable the work piece to be held in the proper position with respect to the movements of the tool for any selected cam when the proper notch is interlocked with the driving lug 34, the dog remaining iixed in the same position on the work piece.

The shaping tool illustrated is a grinding or abrasive wheel 40, secured to a rotary toolholder comprising an arbor 50 rotatably mounted in a movable tool carrier 49 operated through a pivo-ted translating means by a pattern 73. The tool may be rotated by any desired means, such as a belt 41 driven from an overhead pulley and kept taut by suitable belt tightening devices not shown. An adjustable tool carrier and translating means supporting table 42 mounted in suitable ways on the tool base 2l may be adjusted transversely of the work center axis by means of a hand wheel 43 which imparts movement to a transmission device including a lead screw and nut, rack and pinion, or other well known form of machine tool table moving means (not shown) A bracket or hanger 44 is xed to and rises from the front part of the table 42, that is, from the part adjacent to the work table 25. Bracket 44 serves as a support, which is adapted to be secured rigidly to the table, for the tool carrier translating means composed of two-limbed or yoke- shaped levers 45 and 46 pivoted to the bracket 44 on journal bolts 47 and 48, respectively (Fig. 7). The tool carrier consists of parallel links 49, pivoted to levers 45 and 46, in which the arbor 50 carrying the abrasive wheel 40 and belt pulley 51 rotates. Bracket 44 also serves as a protecting housing enclosing the major portion of the circumference of the abrading wheel 40 by means of its curved back wall and two parallel side webs 52 projecting from the concave side of the back wall and merging into the for- In Figs. 1, 6 and 7 an additional shield member 53 is shown attached to the upper forward projection 54 of the bracket.

Yoke shaped lever 45, constituting the forward and idle oscillatory member of the tool carrier translating linkage, comprises limbs 57 connected together by a cross member 62 having a stiening rib 63, and is pivoted or ulcrumed at its lower end on the journal bolts 47 which pass through bearing ears 55 and are threaded, respectively, in sockets drilled Aintothe opposite ends of an enlargement 56 formed on the lower forward portion of bracket 44 in the construction shown. The operating or active lever 46 is composed of two parallel limbs 64 connected near the point of application of the poWer,-at its lower end. as shown, -by a transverse member 65 (Fig. 4) and near the fulcrum endshown as at its upper end-by a shield-like strengthening member 66 curved rear-V ward over the rear of bracket 44. The fulcrum bearings of idle lever 45 and active lever 46 are preferably ball bearings, as shown in Fig. 7 at the fulcrum of lever 46, wherein 70 indicates the bearing balls. A bearing ear 68 on the fulcrum end of each limb 64 is perforated to receive the ball bearing and permit the passage of the journal bolts 48 which are screwed into the ends of enlargement 69 on the bracket 44. At each fulcrum bearing of active lever 46 and idle lever 45 a cover such as cap 71 having a grease hole 72,. with cup or cover therefor, protects the bearing and provides for lubrication. Depending from the lower transverse member 65 of the lever 46 is an extension 67 slotted to receive a bearing roller 66 pivoted thereto, in contact with which is a member for imparting movement to said lever to be presently described.

The parallel links 49 referred to as constituting the tool carrier supporting the tool arbor 50 have their ends vpivoted, preferably by ball bearings, to the levers 46 and 45 as best shown in Figs. 6- and 7. One of these pivotal bearings is illustrated in detail in Fig. 7 wherein 60 indicates a bearing pin ixed to spaced cheeks of one limb of the idle lever 45, and 59 bearing balls interposed between the pin and the' wall of the bearing cavity in one end of the tool supporting link 49 disposed between the cheeks. The bearing pin 60 is shown as tubular with a bore flaring at each end and longitudinal kerfs to permit of expansion of the ends, which may be accomplished by means of an expansion bolt 61 having a conoidal head at one end and a conoidal nut atthe other end. The front end and bearing of each tool supporting link 49 is conned between the cheeks in the upper end of each arm oi idle lever 45 while the rear end and bearing oi each of said links 49 is confined in a slot or' cavity 72 forming spaced cheeks in each limb 64 of the active lever 45. The axis of the pivot connections of the links 49 with idle lever 45 is the same distance from the fulcrum axis of said lever 45, as is the axis of the pivot connection of links 49 to active lever 46 from the ulcrum axis of said lever. When the active lever 46 is in the mid-throw position, as indicated in the drawings, the plane that inclu-des the fulcrum of lever 46 and the axis of the pivotal connection of links 49 thereto is parallel to the plane that includes the fulcrum of lever 45 and the axis of its pivotal `connection to links 49; also,vat this time, theplane including the axes of the pivotal Vconnections of the links 49 to the lever 45 and lever 46 is at right angles to the former planes and parallel'with the plane of adjustment of the tool supporting' table 42. The tool arbor Y50 is journalled in the links 49 about an axis midway between the pivotal connections of the links 49 to the lever 45 and inch in the machine illustrated)v that axis moves l in a plane parallel with the plane of adjustment of both tool and work supporting tables. The movement of any point on the axis ispractically a right line movement, notwithstanding the rocking movement or change in angular position of links 49 due to the opposite directions in which the levers 45 and 46 extend fromV their fulcrum points.

Fig. 13 shows the details of the tool holder comprising an arbor and Vassociated parts and the bearings of said arbor in tool carrier links 49, which are so constructed that the axis of the tool may be maintained with accuracy in the same relative position with respect to the links 49`at all times. The mid portion 100 of arbor 50 is tapered to receive hub 101 of belt pulley 51. Adjacent the small end of tapered portion 100 the arbor is threaded to receive a nut 102 which locks the pulley on the arbor, Abrading or grinding ment when adjustedbyrlock nuts 113.v i

y and-:the'eccentric-.portion or lift of the pattern,

wheel 40 is rsleeved overth'e hub.'101...1tv is `held Y respectively; member' 91 .is preferably removable between .a ange103-on the .pulleyv and a clamping ring 104. A. nut 105 screwed on' a :threaded .part

of the hub 101 clamps ythe wheel-.140` against the 1'iange103.v Suitablegaskets aredisposedibetween thegrinding'wheel and the clamping means.v The end journal portionsil of. arbor '50,arefoppositely tapered and areY` of course smallerindiametertha'ny tapered portion -IOO so that the pultted in openings' viormed in zlinks.` 4:9:.to-.receiver-y the taperedfjournals: of. thexarborL ,..Linksi'49 Vare 1.

provided-:with: .threaded bosses1 `108 coaxial with this". purpose. .'Within ithev cupi likecavity formed byithesextremity of zthe'farbor: and the overhangingjpo'rtion of each bushingsthrustzdisks 111" of isome'goodabearing material are seated; thrust screws. 112-are vthreaded through openings-infcaps f 109; into-'contact .with :the disks-'fand thus main-l i tainzthe endwise adjustment ofthe arbor50; The' thrust screws 11121rnayf=be vvlocked vagainst fmoveyTranslating means :between .the :pattern Van tool carrier for moving-the tooltward and awayY from theY axis: of vthel workto'xgive. tothe .Work a pre-ealculated-contour are-.shown in Figs. 3 and 4.' :In these Yviewsnumeral 73': indicates the-#pattern as illustrated a-master cam, `'which is an enlarged replica of acam tobe'shaped".by:theal: radingv and '77 on 'bracket 22 rigidwith theztool/.base of the apparatus. CShaft'lais rotatedby'saidl elec-'F' ofthe lift. i Where the leverage is in a ratio of 5 to las described the radius of curvature of wear K `member 91fis -ve times the radius o abrading tric motor "78 mountedsonA pedestal-"24., a wormfO rotating with thearmature shaft'19 and driving'ai .-.worm wheel81 lon shaftl 74; )'-Shiaft'iv ltransmitsIv rotationto work rotating-shaftv 3'5vby means Vof a transverse shaft 82 vprovided'with bevel` gears' 83 and -84 on its respective ends whichmeshmes'pec tively .with al bevel gear' 85` on shaftt'74r'andf bevel gear 36 secured. :slidablyitoslfarft53h-asy before'.y stated. i "The gearing. is.s designedrtof give" shafts'M andf35 the same. angularspe'eds.

dicates an .elementmovingin a' straighttline--as 'illustrated avslide reciprocatingiin a'fguide.' Way i ciated moving parts. Atits' forward 'end'.slide 861. y

tailstockythe blankis then indexed to bring the has a lever wear member 89 which bears against" the roller i613'v on' the 'projection-67.1 atlthe power end: oi lever 46.. Detachably-attacliedfto'.theropposite` endgof a slide'86 is a-'yokef90i1carrying at itsrear a pattern wearplate 91fwhich. bears. against'thepattern t'73 and is arranged'. inline with wearmember'89.; Tensionfspring92 has one end att'achedto leverf46 fand-its other-"end 1' attached :to slidev 86,4 with vtheresult` that the -wearr and'replaceable... By thisconstruction the tool is allowedtoapproachthe workr and is moved away fromA itj by ycontrolled 'elastic forces; .all cutting pressureis produced by an elastic force..V To guide the yokeg) a guiding extension 95 vslides in away formediin` arigid'bracket 96. y

--Assuming vthat the lines radiating from theraxis of rotation' of the. pattern. cam .illustratedto its' surfacehaving a-:ratio of 5 with respect tothf' corresponding' lines radiating from l:the .center for l the `finished cam to `beishaped by theltooLthek distance'frcm the fulcrum of lever 46 tothe point of application of .the power,-the raxis of the bear-` ing rolleriGG-is vetimes the distance fromthe fulcrum .to .the point ofapplication of said lever l tothe .work which is the pivotal axisofthecony nectionvof link 249 to'lever 46. With a leverage ,y

of 5:11the1curvatu1'eof .the operating .face ofl wear-.member S9 necessary to compensate for the angular movement of links 49 around the center f z point of oonnection'of link 49'to lever'46 .sufficient 3 to compensate for the decreased relative movement'V of ythe'tool axis due to the slight rocking movement of the `link Y49 on whichthetool is carried.

When the shaping tool is a rotary tool, ksuch as abrading wheel 40 shown inthe drawings, the.

vwearmember91' on yoke`90 is .curvedso .that the high point or extremity of the `lift of the` pattern willfrst contact .with av low peintin the .surface yof v'wear'member and afterward withl the high point thereof .v. In Ythe mechanism 'shown the sur-ju'y face of wear member 91 on yoke-90 is curvedinA a plane at right angles to the axis of patterncamy 73, that is, in the plane that denesthe contour wheel 49. By making thewear member 91V re- 'Imovable it may be removed -iand replacedbyV one 'of a diiferent curvature in case a larger` or smaller abrading wheel is used or after wear of the abrad- "ing- Wheel. f y'Ihus the relation of the abrading -wheel tothe cam beingshaped is substantially" identical with the relation ofthe operating wear :member 91to the pattern'cam.

The operationof the form oi apparatusH illustrated is as follows: Thel work piece or'blank,-

"for a six cylinder internal combustion engine-is insertedy between the centers o the head and blank cam to be ground into the saine angular 'positionas the'pattern or mastercanfi.- vThe tool and work tables are adjusted'tocorrect workingposition forthe particular piece to be shaped. The abrading tool is caused' to rotate on its own axis, and .thepatterncam and work rotating shaft. 'nare' caused to rotate at Videntical angular speeds by the prime mover therefor andthe transmitting mechanism as *explained I hereinbefore.

Spring 92holds the roller 66 on the lower'end of the lever 46i`n contactwith the front end of slide ..86 and rspring 93 Lholds the curved wear' manner as'to impart to the abrading wheel a extent to the right line movementl of the operating slide86 imparted by the pattern cam, as predetermined by the proportions of the cam being ground to those of the pattern cam. The pressure of tool on work is an elastic pressure. A large model of the cam to be ground can be produced with a high degree of accuracy and this can be used as a pattern'to operate or control the relative movements of tool and work. By reason of the proportions of the linkage by which the tool carrier is operated by the pattern cam it is possible to reduce in the lIinished replica the errors that may be present, in spite of the greatest care, in the pattern or master cam. A right line movement of the tool is obtainable through a carrier which is mounted on pivotal bearings instead of sliding on guide ways whereby frictional resistance to the movements of the tool to and from the work is minimized` and a more delicate and precise` functioning secured.

Although we have in accordance with the statutes described the best embodiment of our invention now known to us, we do not intend the patent to be limited to the specific embodiment described as the principles involved are applicable to different :forms of mechanism.

We claim:

1. In pattern controlled apparatus of the class described, the combination of a rotary tool and holder therefor, a work holder, a pattern, means for rotating the work holder and pattern at equal angular speeds, a translating means operated by the pattern comprising a lever mechanism, a carrier pivotally supported on the lever mechanism, l

a bearing on the carrier for the tool holder, and means for causing the axis of the tool holder to approach and recede from the work holder center inright line movements.

2. A combination as dened in claim l, in which the translatingl means operated by the pattern comprises anactuating lever, to which said carthe point of application of the force, due to the lrotation ofthe pattern, to said lever.

3. A combination as defined in claim l, in which the translating means comprises a pair oflevers arranged in tandem and extending in opposite directions from their fulcrum points, said carrier being pivoted to each of said levers on axes equidistant irom the fulcrum points of the levers, said tool holder being supported on said carrier midway between the pivotal connections of the carrier to the levers;

il. A combination as dened in claim 1 in which the translating means comprises a pair of levers arranged in tandem and extending in opposite directions from their fulcrum points, said carrier being pivoted to each lever at points equidistant from the fulcrum points of the levers, a bearing for supporting the tool holder on the carrier at the point of right line movement in the carrier, said pattern being arranged to transmit movement to'one of said levers at a point on said lever that isa greater distance from its fulcrum than the connection of the carrier thereto.

5. In pattern controlled forming apparatus of the class described, a rotatable work holder, a rotatable tool holder, mechanism for moving the tool holder to and from the axis of the work holder, comprising pivoted lever mechanism, `a

carrier supported by and pivoted to saidV lever mechanism, a bearing for. said tool holder on said carrier, means for causing the carrier to move the tool holder axis in a substantially straight line, a

pattern arranged to operate the Y pivotedV lever mechanism, means to rotate the pattern and work holder at equal angular speeds, and means interposed between the pattern and thelever mechas.

nism constructed and arranged to compensate for the angular movement of the carrier and cause the axis of the tool holderto travel a distance proportionate to the-throw of the pattern withV respect to the desired throw of the work piece.

6. A combination as dened in claim 5 in which the means interposed between the pattern and the lever mechanism comprises an element moving in a straight line having one end convexly curved in the plane of movement of the lever mechanism and bearing against a roller on said lever mechanism. i

7. In pattern controlled mechanism of the class described the combination of a rotary work holder, a rotary tool holder, a carrier therefor, a pattern,

means for rotating the pattern and work holder at equal angular speeds, a translating mechanism between said pattern and tool carrier comprising levers arranged in tandem and extending in opposite directions from their fulcrum points, said tool carrier being pivoted to both of said levers at substantially equal distances from their fulcrum points, said tool holder being supported with its axis substantially midway between said levers, an element guided in a straight line movement interposed between said pattern and one of said levers, the end of said element bearing upon the lever at a point further from its fulcrum than the point of connection thereto of the tool carrier and havv ing a curvature in a plane parallel with the plane of the lift of said pattern.

3. In pattern controlled forming mechanism of the class described, a tool holder, a work holder, a pattern, and means for rotating said pattern and one of said holders at equal speeds, a translating means between the pattern and the other holder comprising a pivoted lever, a carrier for said other holder pivoted to the lever, yand means yto guide in a straight line that part of the carrier to which the holder is attached, aislidable member controlledby the pattern, said slidable member having one end bearing against the lever and having said end contoured to compensate for the tilting of the carrier vand a spring arranged to maintain contact between the lever and the end of the slidable memberv bearing against the lever. 130

9. A combination dened in Vclaim 8 with the addition of a spring exerting its elasticity to maintain the slidable member in contact with the pattern.

l0. The combination dened in claim 8 in which 135 the tool holder is rotatable and is mounted on the carrier pivoted to the lever, and the slidable member isprovided with a removable device having a surface arranged to engage the pattern, said surface being of acurvature, in a plane parallel to 14@ the plane of rotation of the pattern, the radius of which has the same proportion to the radii of the

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