US2553831A

US2553831A - Machine for producing cams

Info

Publication number: US2553831A
Application number: US72044A
Authority: US
Inventors: Musyl Robert
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-01-24
Filing date: 1949-01-21
Publication date: 1951-05-22
Anticipated expiration: 1968-05-22
Also published as: FR979269A

Description

y 22, 1951 R. MUSYL mcnmz FOR rnonucmc ms 4 Sheets-Sheet 1 Filed Jan. 21, 1949 INVENTOR:

ROBERT MUSVL ATTORN 3 y 9 1 a. um 2,553,831

MACHINE FOR rkonucmc cms Filed Jan. 21, 1949 4 Sheets-Sheet 2 INVENTOR:

ROBERT MUSVL ATTORNEK May 22, 1951 R, M|J$YL 2,553,831

MACHINE FOR PRODUCING cAus Filed Jan. 21, 1949 4 Sheets-Sheet s Fig.8

"39 0 35 33 3 s as n o U I I I B INVENTOR:

ROBEF? T MUSVL AT TOPNE 4 Sheets-Sheet 4 IN VEN TOR:

R. MUSYL May 22, 1951 MACHINE FOR'PRODUCING was Filed Jan. 21, 1949 Patented May 22, 1951 UNITED STATES PATENT OFFICE MACHINE FOR PRODUCING CAMS Robert Mus'yl, Vienna, Austria Application January 21, 1949, Serial No. 72,044 In Austria January 24, 1948 8 Claims. (Cl. 51-101) The object of the invention is a process and a device or a machine-tool for the precise production of non-circular profiles, and in particular of cams on cam-shafts, or the like, which in many respects presents great advantages over the hitherto known processes and devices.

Hitherto the cams on the cam-shafts have been produced by means of grinding machines, operating according to the copying or duplicating process, which entails the necessity Of using a master-cam of a shape identical to that of the finished cam to be produced, and of employing a copying device for making the shape of said master-cam bear upon the motion of the workpiece, as this is also customary with other copying processes. The disadvantage of that process, however, resides in even a slight wear of the 'tool, i. e. of the grinding wheel in case of grinding machines, entailing 1 modification of the cam shape which has a highly detrimental effect on the operations of control and distribution for which the defective :cam may be used. If an irregular cam-shaft of this kind is e. g. employed in an internal combustion engine the diagram (or chart) of the control and distribution operation is distorted, resulting in a reduction of the engine efiiciency.

It has been found that the motion of the masses in the pure copying process, in which the workpiece executes a swinging or oscillating motion together with the headstock and the tail-stock, impedes an amelioration of the process. Hence, it is one of the main features of the present invention to have the workpiece execute a rotary motion about a stationary axis, whereas to the tool not only the rotary motion is imparted required for grinding, but also a swinging or oscillating motion indispensable for giving the workpiece the outer shape desired.

According to the invention the tool contacts the workpiece continually in the perpendicular to the curve at the time being, whereby with rotary tools said perpendicular to the curve passes through the center of the tool.

Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and claims, and are shown in the drawings which, by way of'illustration, show what I now consider to be preferred embodiments of the invention.

In the drawings:

Figures 1 to 4 diagrammatically illustrate the relative position of the work and of the grinding disc at various operating phases;

Figure 5 is a, diagram showing the path of the 2 grinding wheel relative to the flank of the work which is ground;

Figure 6 is a diagrammatic side view of a mechanism for moving the grinding wheel relatively to the work according to the invention;

Figure '7 is a front elevation of a machine accordingto the invention;

Figure 8 is a top view of the machine shown in Figure 7; I

Figure 9 is a part-sectional view of the machine according to Figures 7 and 8 and taken transversely to the axes of rotation of the work, of the grinding disc, and of the shaft of the motor driving the disc; I

Figure 10 is a plan view of a machine for simultaneously grinding four cams, according to the invention. 7

The Figs. 1-4 show four different positions of the grinding wheel relatively to the workpiece to be machined i. e. in this particular case the cam to be produced. In Fig. 1 the main axis a of the cam coincides with the diameter b of the grinding wheel 0, i. e. the two centers d and e of the cam and the grinding wheel are located in the same horizontal line (i. e. the same level). The perpendicular to the curve, composed of the two axes a and b, passes through the centers d and e. When the cam moves anticlockwise, the center c of the grinding wheel is horizontally displaced in regard to the cam, and is at the same time lifted to the position 6' so that the perpendicular n to the curve occupies the position as shown in the drawing. Consequently, the point e is one of the generating points of the path, to be discussed hereinafter, of said center and of all points of the grinding wheel, i. e. of a socalled relative path R (Fig. 5), the term relative path indicating that said path represents the relative motion of the grinding wheel in respect to the cam flank. As Fig. 2 shows the axis a of the cam N makes an angle of 45 with the horizontal line H. While the cam N continues its anticlockwise rotation, the grinding wheel 0 approaches the cam returning to the position in which the two centers 12 and e are placed on the same level (the same horizontal line), according to Fig. 3. Thus the center 6 and the tool, i. e. the grinding wheel, have returned into the position according to Fig. 1. Then follows the machining (grinding) of the semi-circular limiting arc of the cam N during which period the center of the tool (grinding wheel) remains stationary, whilst the cam executes a rotation through further outof its position accord ing to Fig. 3. This position of the cam is equivalent to that of Fig. 3 but as seen in a mirror; consequently the semi-circular arc of limitation is not located as in Fig. 3, but on top. From this position onwards the operation constitutes by Way of the optionally selected Fig. 4, i. e. the tool (the grinding wheel) has moved downwards entraining the perpendicular to the curve a which passes through the contact point on the cam circumference and the center 6 of the grinding wheel. Finally, both the tool and the workpiece return to their initial position according to Fig. l, whence the cycle of operations begins again.

It results from the above that the workpiece, i. e. the cam to be ground, should have a constant angular velocity, and that the grinding wheel center must occupy, at any moment, a position on the perpendicular to the curve corresponding to the respective position of the workpiece. Thus the grinding is always executed-in the perpendicular to the curve.

In conformity with a suggestion made, but not yet disclosed, the organ corresponding to said movement is decomposed into a first mastercam, taking care of the horizontal component of the motion, and a second master-cam to which the vertical component of the motion is assigned. Both cams are suitably keyed to the same axle in such a manner as to execute the controlmotion in predetermined and unalterable positions in respect to one another. The master-cams are designed in conformity with the cams on the cam shafts or the other non-circular profiles envisaged, so as to operatively warrant the production of the correct profile, regardless of the size and the wear of the grinding wheel.

A further suggestion, likewise not yet disclosed, provides for a special gear, intended to transmit the motion of the master-cam pair on to the grinding wheel by lodging the grinding wheel together with its drive in a casing block and by imparting to same, and consequently also to the grinding wheel and the motor, a swinging or oscillating motion. As the said parts, as well as the gear necessary for the drive, are of a con- 'siderable weight, there ensues the disadvantage of the weight of the moving masses unduly limiting the oscillating frequency of the grinding assembly and consequently also the efficiency of the entire machine-tool. This oscillating frequency is limited. Moreover, the weight of the oscillating masses renders necessary a most rugged construction of the machine-tool, far exceeding the conventional sizes. Finally, the nature of the drive bears upon the shape of the master-cams so that the number of the shapes of the cams, or in general of the non-circular profiles which can be produced on such machines is restricted. These considerations have given rise to the new design of a cam grinder according to the present invention which, as will be seen from the following, solves the problem in the simplest manner possible.

The essential feature of the process consists in that the workpiece rotating with a constant angular velocity, as described above, is continually subject to be ground in the perpendicular to the curve.

The essential feature in realizing this process consists in that a purely mechanical gear is used for operatively keeping the tool in the perpendicular to the curve.

According to a special embodiment of the invention, complying with the above features, two master or standard cams are provided which bear upon the tool exclusively by way of simple feelers or contacting arms so as to compel said tool to always occupy a position in the perpendicular to the curve while acting on the work? piece.

In the course of the further development of the invention it has been found indispensable to insert, between the two master-cams and the tool, a link motion combining the horizontal and the vertical master-cam control movements intoa resultant, and transmitting same to the tool. The link motion consists of two links cinematically interlocking. According to a special embodiment of the subject matter of the inventionthe one contactor arm for the vertical component of the movement consists of a roll-carrying feeler which is by weight continually forced to rest on the master-cam for the vertical tool motion, and which forms a portion of a one-armed lever or the projection of such an arm, carrying on itsfree end a pendulum lever with the tool. A further feature of the invention consists in that the second contactor arm is constituted by the free end of the pendulum lever itself, said free end having the shape of a roll, and resting, in the manner of a feeler, on the flank of a control slide e. g. under the action of a spring, said slide being. solely displaced in the horizontal direction by the master-cam controlling the horizontal com-- ponent of the total motion.

A further feature of the invention renders itpossible to exclude the motor from the moving masses and to exclude at the same time also allaccessory parts, such as the casing, a special oscillating frame, etc., from participating in the swinging or oscillating motion. A further feature of the invention provides the drive of the tool i. e.- of the grinding wheel-being effected by way ofthe one-armed lever and of the pendulumlever, the driving motor being located so that its axis coincides with the center of the fixed link of the one-armed lever, the driving force being thus transmitted from the motor pulley to a pulley arranged at the point of linkage of the pendulum lever and the one-armed lever, and thence by a belt drive to the pulley coaxial to the tool i. e. the grinding wheel.

Owing to the suppression of the superfluous moving masses according to the above th design of the machine-tool can be considerably simpli fied, but additionally there ensues the advantage that for grinding a cam shaft a plurality of units, as described in the following, can be arranged on the same machine-tool, capable of operating individually, or in pairs on the same or on opposite sides of the cam shaft. This eliminates the danger of breakages due to critical oscillating frequencies or interference phenomena. By this arrangement of simultaneous operation the working time is considerably reduced, and the working precision is greatly enhanced, which is a feature of particular importance in modern motor and engine construction.

As appears from Fig. 6 two master-cams i and 2 are arranged on a shaft having the axis M, the master-cam l serving to produce the horizontal component of the motion of the tool i. e. of the grinding wheel 3, whereas the other master-cam 2 is used for taking care of the vertical component of the motion. A one-armed lever 5 is supported by a fixed link 4 which by these articulations is prevented from executing other motionsthan vertical ones. The free end of said onearmed lever 5 carries at 6 a pendulum lever l to the free bottom end of which i. e. at 8-the tool,

viz. the grinding wheel 3 is fastened.

The lever '5 is fprovidediwith fa projection carryin'ga small roll, ii I which by the weight {of the device is continuallyjpressed on fthecircum ference of the master-cam 2 so as tomove, feelerlike, in unison withthe eccentricities of the co n tours of the'master-cam 2, thustransmittingits motion'fto the; lever 5, and consequently 'to the pendulumlever'l. n I H As regards the second'master cam I its contour is made to control the arm' E2 of the slide E3, the second arm [4 of which reaches into the range of a roll l5'so as to have said roll l5 con-f tinually contact the said arm 14. This perma;

more correctly, the driving system is excludedfrom the swinging or oscillating system by the motor .29 being located atpoint 4 (fixed link) and thence driving a pulley 2! which transmits the force of'the'rnotorby way of a belt to a pulley 22 located at point 5 (point'of linkage), whence the" force is further transmitted by a belt drive to the'pulley 23 at the bearing 8. The slide I3 is made to travel in the guide 24 of the machinebedZFi.

"By realizing the above principles a very simple andlight-weight machine-tool is obtained as illustrated in the Figs. 7, 8 and 9. The device described above is lodged in the fixed casing 30, the levers 3| and 32 serving for starting and stopping the grinding wheel drive and for changing the speed, whereas the workpiece, i. e. the cam shaft 33 with the cams 34 is taken up between the headstock 35 and the tailstock 35 The

hand wheels

35 and 31 arelused for moving the workpiece chucks or fixing devices to orirom the tool, or for displacing it in parallel thereto.

the synchronous drive for the cam-shaft motion, whilst the drive of the master-cams l and 2 is eifected by a synchronous motor in dependence on the rotation of the workpiece.

The adjustment of the master-cams I and 2 is carried out by operating the hand wheel 39. Fig. '10 is a plan showing a multi-tool arrangement provided with simplified controls.

Stress is laid on the fact that the device according to the invention permits, first of all, the con struction of a unit composed of the tool and its bearing, of the feelers or contacting levers, of themaster-cams, and of the drive for -the tool and for'the master-cams. Taking a step further these units can be built into machine-tools,- as

described, whereby single units or a plurality ofunits may be provided, the latter acting either sideby side or opposite to each other.

Numeral 413 refers to the foundation frame or base plate of the machine-tool on which the known headstock 4! and-thetailsto'ck 42" are "so located as to be displaceable thereon. *Between the centers the workpiece i. e. the camshaft, carrying twelve cams, is set, said cams being machined simultaneously by means of efg. fourunits 44, 45'and 46, 41, said units being fixed in pairs on projections 48 and 49, and being displaceable toa certain distance in the longitudinal direction of the machinetool.

usd for the"displa'cement"o'f the master-cam shaft on the one hand, and on the other hand The'head stock 35 serves at the same time as housing for speed are provided.

fgr ithe adjustmentor t emess tojbej' used forfthe'work at hand. Besides for .2 91

unit, a leverf52 forstarting and stopping the;

grindingdevice, and a lever 53 forchanging Finally there are hand wheels side of the machine-tool table, for moving the units 'in' pairs towards or from the workpiece, and another band wheel 55 for displacing the two, pairs of units in par-alleltothe axis of the workpiece. Furthermore, a hand wheel '56 is provided for'longitudinally displacing the table on which the workpiece is fixed.

"Byiine'ans of the machine described which by the wayrnay also be fitted with one-pair units,

all cams of a four-cam shaft can be ground at once whereas an eight-cam shaft would require two successive operations, and a' twelve-cam shaft three operations.

As already mentioned above the invention'is not restricted to the production of cams or cam-' shafts. If the two master-cams which are required for the horizontal and the vertical Inc-- tion of the grinding wheel are so designed that i the workpiecer0tating at a constant angularvelocity -is always machined in the perpendichlar to the curve, then it is always possible to produce on the same machine-tool all kinds of noncircular bodies such as triangular profiles as known. The shape and siz of the masters will, of course, have to be altered according to the profiles to be ground. In case of the triangular.

profiles eccentrics are employedof which thejone controls the horizontal motion of the tool, whilst the other having e. g. an eccentricity three- 'time'sT 1. Machine for the production of cams comprising in. combination a fixed holder for the workpiece, a movable holder for rotatingly car- I ying the tool, two rotary master-cams, means inserted between said cams and the said tool holder for moving same horizontally. under the actions); the one cam, andvertically under the action of the other cam, the means for horizontally moving .thetool consisting in a channelshapedstirrup displaceable. under the action of the..,o'ne master-cam, and the means for vertically displacing the tool consisting of a onearined lever restingby means of a contacting organ on or againstthe other master-cam, and keepingthe tool swingingly suspended from its fli'BQfiIldgdl'lVlng means for the tool, and driving means for the master-cams.

2.-.Machi ne for the production of cams comprising in combination a fixed holder for the workpiece,-a movable holder for rotatingly carryingthe tool, two rotary master-cams, means inrdp' displaceable--under the action of the one master -cam, andthe means for vertically dispnemgihe toolconsisting of a" one-armed lever resting by means of a contacting organ on or 54, oneon each against the other master-cam, and keeping the tool swingingly suspended from its free end, a pendulum lever being linked to the free end of the one-armed lever, resting under its own weight on the one master-cam by way of a contacting organ, the face bottom end of the pendulum lever carrying the tool whereas its free top end is acted upon by a tension spring so as continually to press a roll, coaxial to the tool, against the one arm of the channel-shaped stirrup for the purpose of keeping it in contact with the other master-cam, driving means for the tool, and driving means for the master-cams.

3. Machine for the production of cams comprising in combination a fixed holder for the workpiece, a movable holder,for rotatingly carrying the tool, two rotary master-cams, means inserted between said cams and th said tool holder for moving same horizontally under the action of the one cam, and vertically under the action of th other cam, the means for horizontally moving the tool consisting in a channel-shaped stirrup displaceable underthe action of the one master-cam, and the means for vertically displacing the tool consisting of a onearmed lever, resting under its own weight on said one master-cam by means of a contacting organ consisting of a roll, running on the circumference of the master-cam, a pendulum lever being linked to the free end of the one-armed lever, the free bottom end of the pendulum lever carrying the tool, whereas its free top end is acted upon by a tension spring so as continually to press a roll coaxial to the tool against the one arm of the channel-shaped stirrup for the purpose of keeping it in contact with the other master-cam, driving means for the tool, and driving means for the master-cams.

4. Machine for the production of cams comprising in combination a fixed holder for the workpiece, a movable holder rotatingly carrying the tool, two rotary master-cams, means inserted between said cams and the said tool holder for moving same horizontally under the action of the one cam and vertically under the action of the other cam, the means for moving the tool in the horizontal direction consisting of a channel-shaped stirrup displaceable under the action of the one master-cam, whereas the means for moving the tool in the vertical direction consist in a one-armed lever resting by way of a contacting organ on the other cam, said contacting organ being provided with a roll, running on the circumference of the second rotary master-cam, a pendulum lever carrying the tool, being linked to the free end of the onearmed lever, and being acted upon by a spring so as to press a roll, coaxial with the tool, on a shank of the channel-shaped stirrup, the tool being driven by a double belt drive from a motor, the axis of which coincides with the fixed link of the one-armed lever, the belt passing from the motor pulley to a guide pulley, coaxial with the axis of linkage of the pendulum lever and thence to the tool driving pulley, the means for driving the master-cams consisting of a motor and a power transmission gear for the cams.

5. Machine for the production of cams comprising in combination a fixed holder for the workpiece, a movable holder rotatingly carrying the tool, two rotary master-cams, means inserted between said cams and the said tool holder for moving same horizontally under the action of the one cam and vertically under the action of the other cam, the means for moving the tool in the horizontal direction consisting of a channel-shaped stirrup displaceable under the action of the one master-cam, whereas the means for moving the tool in the vertical direction consist in a one-armed lever resting by way of a contacting organ on the other cam, said contacting organ being provided with a roll, running on the circumference of the second rotary master-cam, a pendulum lever carrying the tool, being linked to the free end of the one-armed lever, and being acted upon by a spring so as to press a roll, coaxial with the tool, on a shank of the channel-shaped stirrup, the tool being driven by a double belt drive from a motor, the axis of which coincides with the fixed link of the one-armed lever, the belt passing from the motor pulley to a guide pulley, coaxial with the axis of linkage of the pendulum lever and thence to the tool driving pulley, the means for driving the master-cams consisting of a motor and a power transmission gear for the cams, all these parts including the driving motors for the master-cams and the tool constituting a unit, one such unit or a plurality of such units being set on one or on the two sides of a grinding machine for the purpose of grinding at the same time several cams on one cam shaft.

6. Machine for grinding cams, particularly cams on cam shafts, comprising, in combination, a work holder, a first lever, a pivot swingably supporting said first lever, a second lever swingably supported by said first lever, a tool shaft rotatably supported by said second lever, a horizontal slide having two vertical guide surfaces, a first master cam engaging one of said guide surfaces for effecting horizontal movement of said slide to and from the work, and a second master cam engaging said first lever and oscillating it on said pivot, a roller mounted on said tool shaft and engaging the other guide surface for assuring vertical up-and-down movement of said shaft upon oscillation of said first lever.

'7. Machine for grinding cams as defined in claim 6, comprising resilient means connected with said second lever and a stationary part of said machine for affording engagement of said first lever and said second master cam and of said roller and said other vertical guide surface.

8. Machine as defined in claim 6, comprising a motor for driving the grinding disc, the rotation axis of said motor coinciding with the rotation axis of said pivot, a pulley supported by said levers and having an axis of rotation coinciding with the axis on which said second lever swings on the first lever, and drive means connecting said motor and said pulley and said pulley and said shaft.

ROBERT MUSYL.

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

UNITED STATES PATENTS Number Name Date 2,091,456 Rybick Aug. 31, 1937 2,209,538 Rabe July 30, 1940 2,415,062 Green Jan. 28, 947

FOREIGN PATENTS Number Country Date 417,612 Great Britain Oct. 9, 1934