US1256461A - Cam-path-generating machine. - Google Patents

Description

E.E. FOSTER.

CAM PATH GENERATING MACHINE. APPLICATION FILED ocr.24. 1913.

Paitented Feb. 12, 1918.

EDWARD E. FOSTER, OF BEVERLY, MASSACHUSETTS.

CAM-PATH-GENERATING MACHINE.

Application filed October 24, 1913.

To all whom z't may concern:

Be it known thatl I, EDWARD E. FOSTER, a citizen of the United States, residing at Beverly, inthe county of Essex and State of Massachusetts, have invented a new and useful Improvement in `Cam-Path-C'renerating Machines, of which the following is a specification.

The present invention relates to machines for generating cam paths.

Heretofore it has been customary in the manufacture of barrel cams to plot the cain path upon paper and then scratch the generated cam path upon a rectangular sheet of zinc which is then wrapped or developed about a cylindrical piece of cast-iron. The cylinder is then cut down to the inner working surface of the cam path after which the cylinder is inserted into a cani cutting machine where it direct-s the operation of the cutting tool. As a cam may actuate a follower with a harmonic motion, a uniform motion or a gravity motion the plotting of a path for a barrel cam requires considerable knowledge, skill and experience upon the part of the designer.

The object of the present invention is to produce a machine by which a barrel cam path may be accurately generated by an 0perative having little or no training in the design of cams.

To the accomplishment of this object, and such others as may hereinafter appear, the features of the invention relate to certain devices, combinations and arrangements of parts, hereinafter described and then set forth broadly'and in detail in the appended claims, which possess advantages which will be apparent to those skilled in the art.

The various features of the present invention will be best understood from an inspection of the accompanying drawings illustrating a machine for generating a barrel cam path for imparting harmonic motion to a reciprocating follower in the best form at present known to me, in which,

Figure 1 is a perspective of the machine,

Fig. 2 is a sectional elevation of the crank for reciprocating the tool, and

Fig. 3 is a sectional elevation of the tool carrier and its associated parts.

In the illustrated embodiment of the invention the cam path is generated directly upon a leader by a tool which is rotated` to scribe a circle upon the leader having a di- 5 ameterv substantially equal to the diameter Specication of Letters Patent.

Patented Feb. 12, 1918.

serial No. 797,079.

of the follower employed with the cam. The

leader is reciprocated to transfer the point of operation of the tool along the leader and the tool is reciprocated transversely't''the path of reciprocation of the leader to change the direction ofthe path scribed by the tool upon the leader. The tool is reciprocatediby a crank in the specic form of the'in'ven'tion selected for the purpose of illustration and consequently a cam path for imparting a harmonic motion to the cam follower is generated. It will be apparent to those skilled in the art, however, that mechanism for re# ciprocating the tool with either a uniform or a gravity motion may be substituted for the crank. In order to adapt the machine for generating any desired cani path adjustments are provided for varying tie operation of the tool in accordance with variations in the base circles, rises, drops. dwells and times in the dierent forms of cams to be designed. The leader, which is preferably a rectangular sheet of zinc, is clamped on a leader support 1 with one edge engaged with a shoulder 2 formed on the leader support. The support 1 is mounted to slide on ways 3 carried by a shelf i projecting from a table 5 supported by legs (not shown). The support 1 carries a rack 6 which is engaged by a gear 7 carried upon the upper end of a vertical shaft 8 which is journaled at one end in a boss 9 suitably bored in the table 5 and at the other end in a step bearing 10 formed in a sleeve 11 loosely mounted on a horizontal shaft 12 journaled in bearings depending froin the table 5. The shaft also carries a bevel gear 18 which meshesV with a gear 14 carried by the shaft 12 and also with a gear 15 carried by a sleeve 16 loosely mounted on the shaft 12. Secured to the sleeve 16 is a disk 17 which is provided with an index 18 on its periphery cooperating with a pointer 19 secured to an overhanging bracket 2O carried by the table 5. The index is graduated in degrees and the gears 13, 14 and 15 are proportioned to impart a complete rotation to the gear 7 when the disk 17 is rotated to transfer the pointer 19 one complete revolution around the periphery of the disk 17. rlhe gear 7 is proportioned to transfer the point of operation of the scratching tool to be described from one lateral edge of the leader to the other lateral edge during one complete revolution. Splined to the shaft 12 is a second disk 2l. The 'backs of the disks 17 and 21 I 'j a clamping bolt 33.

rotate in engagement with rolls 22 (only one of Which is shown) which hold the disks pressed toward each other. Y

In order to scratch a cam path upon the leader carried by the support 1 the machine isprovided with a scratching tool 24 which isheld by a screw 25in a block 26 'carried by a carrier 27. The carrier 27 is secured to a sheave 28 carried by the loiver end of a vertical shaft 29 Which is rotatably mounted ina chamber 30 formed in a frame 31. The frame 31 is secured to a horizontal rod 32, mountedto reciprocate in the bracket 20, by v The sheave 28 is ydriven from som/e suitable source of power so that the tool may beA rapidly driven to scratch a circle upon the face of the leader. 'As

the diameter of this circle is substantially equal to the Width of the cam path, or the diameter of the cam follower, provision is made for adjusting the tool to scratch different sizes of circles in accordance with the dierent Widthsof cam paths to be generated. To this end the block 26 may be adupon the leader When the tool is adjusted in line WithA the axis 'of the shaft 29, or may be actuated to scratch a circle having a diameter equal to the length of the carrier 2T Y When the tool is placed at one end ofthe carrier 27.

To serve as a guide for the adjustment of the block 26 on the carrier 27 the carrier isv provided with an inde-x 34. The adjusted position of the tool 24 on the carrier '27 is maintained by a clamping screwY 35 arranged to bind the block 26 on the ways o-f the carrier 27. The tool 24 is pressed against the face of the leader by a sprino' 3G which is-interposed between` the top oit the shaft 29 and the end of the chamber 30. In order to elevate theetool 24 against the tension of the spring 36 the frame 31 carries a horizontal shaft 37 one end of which is provided ivith a knurled knob 38 and the other end of which carries CJl Cit

' an eccentrically mounted pin 39 arranged to engage a groove 40 formed in the shaft 29.

Vith this construction av turnof the knob 38.

elevates-the tool from the facey of the leader. To hold the tool elevated the frame 31 carries a spring plunger 41 which' engages a ation of the tool during the reciprocation of the leader so as to change the direction of its `path the rod 32.is connected to a yoke 43 mounted to slide `upon guides 44 carried by the 'bracket 20. The yoke 43 embraces a rectangular block 45 Which is swiveled upon a crank pin 46 slidably mounted ina slot 48 formed in a platform 49. The platform is secured tothe upperend of a vertical shaft- 50 the upper end of Which is journaled in a bearing carried by the bracket 20 and the lower end of Vwhich is journaled in 'a step bearing 51 carried by the shafty 12.

sired position of adjustmentitcarries a bolt 47 by 4means of which the crank pin 46 `and block 52 may be clamped to each other and t0 the platform 49.` Vith this construction Y the tool 24 is reciprocated towardand from the axis of the leader by a` crank which is driven by the rotation of the shaft 50. As it isdesirable to vary the throwof the crank the upper face of theplatform 49 is pro-V vided with an index toV serve as a guide to the operative in adjusting the yoke 43 and its associated parts nearer to or farther from the axis of the shaft 50. To guide the tool 24 to reciprocate transversely to the path of reciprocation lof the'leader 1 the bracket 20-ca-rries a horizontal rod 54 arranged in a vertical planeV intersecting the axis of the leader. The rod 54 loosely passes through the frame 31 s0 that theV tool may reciprocate freely thereon and thus be constrained to move transversely toward and from vthe medial line of the leader.Y

In orderl to simultaneously reciprocate the leader and the tool the shaft50 carries a desired distance bet-Ween the axes of 1 the fdisks and the peripheries thereof to vary the speed of rotation of the-shaft 50. To this end the roll 55 carries a ring 56 vwhich rotates upon anarm 57 loosely embracing t-he shaft 50 and projecting from a clamp 59 which is mounted on a vertical rod 59 carried by the bracket 2O and the bearing 51. rIhe rod 59 is provided with an index to serve as a guide for the adjustment of the roll along the shaft l50 by the operative. YVith, this construction When the operative rotates the disk 17 in the directionof thearrow Fig. 1, the leader and t-oola-re simulf taneously reciprocated. .v f

In using the machine to generate a cam path intended to impart. for instance, a harmonic rise of 2 inches in-90 degrees, a harmonic drop of 2 inches in 45 degrees, yand a davell during the remaining angle, the frame 31 is adjusted upon the rod 54Y so that the distance from the center of the shaft 29 to one longitudinal edge of the leader corresponds to the base vcircle of the cam path tobe generated. The rodj54 is proilo vided With an index to serve asia guide for; j,

the Ioperative in adjusting .theftool forthek base circles. After this adjustment is made the frame 31 is temporarily held by a screw 60 which clamps the frame 31 to the rod 54. The bolt 33 is then loosened to free the rod 32 and the yoke 43 is then adjusted along the platform 49 until the axis of the swiveled block is one inch from the axis of the shaft 50. This adjustment is made when the platform 49 is positioned so that a mark 61 thereon registers with a mark 62 on the upper face of the bracket 20 at which time the crank is at its limit of movement in one direction. After this adjustment is made the frame 31 is unclamped from the rod 54 and again clamped to the rod 32. l

Now it being desired to genera-te a cam path for imparting t-o a cam follower a harmonic rise of 2 inches in 90 degrees the roll is adjusted on the shaft to such a point that when the disk 17 is rotated to transfer the pointer 1S from the 0 mark to the 90 mark on the index the roll 55 will rotate one half a revolution and thus rotate the crank from its limitvof movement in one direction to its limit of movement in the other direction. The parts being adjusted as described, the operative rotates the disk 17 until the pointer 19 reaches the 90 mark on the index 18. During the rotation of the disk 17 the leader rotates through 90 degrees and the rotating` tool 24 is reciprocated away from the axis of the leader thus generating upon the leader a cam path which will impart to a cam follower a harn monic rise of 2 inches in 90 degrees. To obtain a harmonic drop of 2 inches in the next 45 degrees the roll 55 is adjusted to the mark on the rod 59 so that the roll will again revolve a half rotation as the point travels from the 90 mark to the 135 mark on the index 18. Then. this disk is again rotated until the 135 mark is reached. During this movement of the disk 17 a cam path is generated on the leader which will impart to a cam follower a harmonic drop of 2 inches in 45 degrees. To obtain a dwell during the remaiiiing angle of 225 degrees the axis of the block 45 may be brought in line with the axis of the shaft 50l so that during the continued rotation of the disk 17 to bring the pointer 19 back to 0 or, stated in another way, to complete the 360 degree rotation of the gear 7 the tool remains stationary upon the rod 54. lt is preferred, however, to clamp the frame 31 to the rod and unelamp the frame from the rod 32 to prevent accidental displacement of the tool.

It will be readily apparent that the present invention could be used to generate a cam path cut in a plane as well as a cam path for a barrel cam.

Vihile the machine has been described as generating a specific cam path it will be readily apparent to those skilled in the art that the machine is adapted to generate any cam path for imparting to a reciprocating cam follower either a harmonic motion or a dwell as thel machine is provided with the necessary adjustments for varying the operation of the tool upon the leader in accordance with the variations in the base circles, rises, drops and times of the cam paths which it may be desired to generate.

While the invention has been illustrated and described in connection with a machine for generating a cam path for imparting harmonic motion to a reciprocating follower it must be understood that this is merely one embodiment of thc invention which may have a variety of forms depending upon the kind of motion which it is desired to impart to afollower, the kind of cam to be provided with a cam path, and whether the follower is offset or reciprocates or oscillates. Neither is the specific construction and arrangement of parts shown and described essential, nor is the conjoint use of all the features of the invention essential, except so far as specified in the appended claims, and it may be varied or modified without departing from the broader features of the invention.

What is claimed as new is:

1. A machine for generating cam paths, having, in combination, a leader support, a tool for scratching the leader, means for imparting rapid circulatory movements ofv slight amplitude to the tool, mechanism for reciprocating the tool, mechanism for reciprocating the leader support, and a sin gle means for operating said mechanisms, substantially as described.

2. A machinefor generating cam paths, having, in combination, a leader support, a rack carried thereby, a gear for driving the rack, a tool, a crank for reciprocating the tool, and means for driving the gear and crank, substantially as described.

EDVARD E. FGSTER.

VVitn esses CHARLES E. GRUSH, ELMER B. GRUSH.

Copies of this patent kmay be obtained fox` five cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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