US2317740A - Variable face cam - Google Patents

Description

April 27, 1943. H. DEVLIN VARIABLE FACE CAM Filed June 9, 1941 2 Sheets-Sheet 1 A ia! 27, 1943. H. DEVLIN VARIABLE FACE CAM Filed June 9, 1941 2 Sheets-Sheet 2 HENRY Dam/N I NVENTOR I Patented Apr. 27, 1943 VARIABLE FACE CAM Henry Devlin, Saginaw, Mich, assignor to Baker Perkins Inc., Saginaw, Mich, a corporation of New York Application June 9, 1941, Serial No. 397,278

2 Claims.

This invention relates to variable cams in which a cam follower is selectively directed through alternative cam tracks to impart variable motion to mechanism driven by the cam follower, and has for its object the provision of a continuously driven face cam having communicating circular and eccentric tracks, together with switch mechanism for directing the cam follower selectively into one track or the other. The switch mechanism of my novel cam is actuated during rotation of the cam by engaging a movable abutment member, which member is selectively moved to or from switch-changing position by any suitable part of the machine with which the cam action is to be co-ordinated. This improved cam has the advantage over drum cams heretofore employed for this general purpose that it occupies no more space than a conventional cam, and may be installed in many existing machines having fixed cams with little or no alteration of the machine. Where a drum cam is used the machine frame and drive mechanism ordinarily must be designed especially to accommodate it.

An application of the cam of this invention to a specific machine is described and illustrated in my copending application for improvements in dough dividers, Serial No. 346,176, filed July 18, 1940, of which this present application is a continuation-in-part.

A cam embodying the features of the invention is illustrated in the accompanying drawings, showing the switching mechanism in diiferent positions, in which Fig. 1 shows one form of the cam and its follower mechanism, the cam follower leaving the inner eccentric cam track;

Fig. 2 shows the follower in the outer circular track about to be intercepted and directed into the inner track; and

Fig. 3 shows a modified cam also embodying the invention having its eccentric track outside of its circular idling track.

Referring to Figures 1 and 2!, a cam 28, which rotates counter-clockwise, has a circular outer track 35 and an eccentric inner track 36. Track 36 communicates at both ends with track 35. A cam roller 2! journaled on a rocker-arm 26 rides in the tracks and is actuated by the eccentric track to rock a lever arm 25 of an associated mechanism for any desired purpose, in known manner. The lever arm is actuated at desired periods by the operation of the switch mechanism to direct the cam roller 21 through the eccentric track 36. When the switch mechanism directs the cam roller through the circular track 35, the

lever arm remains at rest, though the cam continues to rotate.

The construction and operation of the switch mechanism is as follows:

Two switch points 37, 38 are pivoted on. the cam at opposite ends of track 36. When point 31 directs the cam follower 2! into the inner track, the driven lever 25 is rocked to the right, then to the left as the follower leaves track 36. The switch points 37, 38 are fastened to pins 39 and 40, respectively, passing through and journaled in the body of the cam 26. Levers 4| and 42 are fixed to pins 39, 40, respectively, and are interconnected by mechanism for moving the points, which is next described.

For purposes of clarity, in Figs. 1 and 2, the cam body is shown in broken lines, the levers 4|, 42, and the switching mechanism being drawn solid, whereas actually the levers are on the opposite face of the cam from the switch points and the cam tracks. Lever 41 of switch point 31 has pivoted to it a rod 43, which passes through the eye of a guide 44 fixed to the cam body. Rod 43 extends slidably through a bushing or sleeve 45 which is pivoted to the end of lever 42 of switch point 38. Beyond the sleeve a collar 46 presents an internal shoulder 41 which engages a shoulder on the rod 43. Collar 46 is slidable upon the reduced end portion of the rod and is urged yieldingly inward by a spring 48 bearing against a washer at the end of the rod.

A latch 49 is pivoted on the cam body, a spring 50 urges the latch normally into engagement with the collar 46, and a roller 5| on the latch is positioned to engage a movable abutment member 53 during rotation of the cam and reelase the latch.

Fig. 2 shows the switch point 31 open to pick up the cam roller 21 and direct it into the inner track 36. The latch 49 is released, and collar 46, lever 42, rod 43, and lever 41 have been moved to the left by the pressure of springs 48 and 52.

Fig. 1 shows the roller 21 leaving the inner cam track 36. As the cam rotates counter-clockwise the roller 2'! opens switch point 38, moving the switch lever 42 and sleeve 45 down against collar 46. This compresses spring 48 and urges the cam 43 down, drawing the switch point 3'! closed and compressing the other spring 52. The spring latch 49 engages the shoulder of collar 46 and holds switch point 31' closed. The cam roller 21 will therefore follow the circular track 35 and will impart no motion to the knife lever 25 until such time as point 31 is again opened and the roller re-enters the eccentric track 36. On the next revolution of the cam, the follower 27 engages the back of switch point 38 and closes it, sleeve 45 sliding up rod 43. On subsequent rotations of the cam the outer track 35 is unobstructed and operation is noiseless.

To trip the latch 49 and switch the follower 2'! into the inner track 36, an abutment lever arm 53 is fixed to a machine shaft operable to move the arm into the position shown in Fig. 2 whenever operation of levers 23 and 25 is desired. In this position it lies in the path of travel of the roller 5| on the latch 49. When roller 54 engages it the latch is moved to release collar 46. The springs 48 and 52 then move the rod 43, collar 46, and switch lever arm Al downward in Fig. 2, opening the switch 37. llhe cam follower 21 will then be directed into the inner track 36.

As the main shaft 23 rotates counter-clockwise the cam follower passes into the outer track (see Fig. 1) forcing the switch point 33 open. The switch lever 42 and its sleeve 45 move along rod 43, urging the collar 56 into a position where it will be re-engaged by the spring latch 39. Through spring 48 the rod 43' is urged endwise and closes the other switch point 3?. This. operation will be repeated each revolution of the cam so long as the abutment-engaging means 53 remains in the path of the latch abutment Si, or if the abutment-engaging means be moved out of the path of latch roller 5!, the cam follower 21 will be directed into the circular track 35, where it will ride idle as described in the second paragraph above.

Certain details of construction in the mechanism as shown and described may be altered without departing from the invention as claimed herein. If desired, the circular idling track may be made smaller than the eccentric track and located within it, requiring only that the direction of swing of the switch points and the arrangement of their actuating mechanism be changed, without altering the: essential operation of the invention.

An embodiment of the invention, so modified, is illustrated in Fig. 3 in which elements identical with those of the cam above described are given like reference numerals. cular idler track 55 with an eccentric track 53 The cam 23a has aciroutside of it. The camv roller 27 on rocker 26 follows the tracks and is actuated by the eccentric track to rock the lever arm 25-. The switch points 57 and 58 are mounted at the ends of the eccentric track 56 on pins 59. and 85 respectively. The pins are journaled in and extend through the body of cam 25a. When the cam rotates counter-clockwise, as indicated by the arrow, the switch point 5'! directs the follower alternatively into track 55 or track 55.

The mechanism for actuating and controlling the switch points, mounted on the opposite side of the cam, is shown in broken lines. Levers El,

152 are fixed to pins 58 and 60, respectively. Le-

ver 6i has pivoted to it a rod 63 slidable in a guide 64 fixed to the cam. Rod- 53 is slida'lole also in a bushing 65 pivoted to the end of switch lever '62. A collar 6% bearing against a shoulder (not shown) on rod 63 is slidable on the reduced end portion of 63 and is urged to the left by coil spring 68 which bears against a stop washer at the end of the rod. A second spring 69 bears against guide 64 and the socket which pivotall-y connects rod 63 to lever 6!.

A latch assembly comprising a latch 59 pivoted to the cam, a spring 50, and a roller 5|, is constructed and operates like the latch assembly in Figs. 1 and 2. The roller 51 is positioned to engage the movable abutment member 53 on the associated machine and urge the latch out of engagement with the collar 66.

The operation is as follows: the points as shown in solid lines are positioned to direct the follower 21 through eccentric track 56 to rock the lever arm 25, the abutment lever 53 being in position to contact the latch roller 5|. As the cam revolves the follower 21 will engage the outside of switch point 58, to close it across the idler track 55 in the position shown in dotted lines. This action will move lever 62 to the right into the position indicated in dotted lines, carrying the collar 66 to the right into engagement ith the latch, compressing spring 68, and drawing rod 63 to the right. This in turn will rock lever 6| clockwise and open switch point 51, as indicated by dotted lines. On thenext and subsequent revolutions of the cam the follower 21 will follow the circular idler track 55, opening point 58, which can be moved freely indirection by reason of its lost motion connection with rod 63. The follower will continue to travel in this path unless and until the abutment member 53 is moved into position to trip the latch again.

Having described the construction and operation of the foregoing embodiment of my invention, what I claim and desire to secure by Letters Patent is:

1. Inv a face cam, a circular idler track, an eccentric. track opening at its ends into said circular track, a switch. point at each end of said eccentric track between it and said idler track, pivotally mounted so that a cam follower can be selectively directed during rotation of the cam to pass either through said eccentric track or said idler track, a connection between said switch points operable to close the leading switch point in response to displacement of the rearward switch point by the cam follower passing out of the eccentric track toclose the leading switch point across said eccentric track, resilient means normally urging said leading switch point open across said idler track to direct the cam follower into said eccentric track, and spring latch means arranged normally to retain said leading switch point closed across said eccentric track, and an abutment on said latch means for engagement with abutment-engaging means movable to and away from the path of travel of said latch abutment during rotation of the. cam, said latch abutment operable on engagement with said abutment-engaging means to release said latch means to permit the leading switchpoint. to close off the idler track and open the eccentric track to direct the cam follower thereinto.

2. The combination claimed in claim wherein the. rearward switch point has a: lost-motion connection with. the leading switch point, so that its motion. is effective only to. close. t'ncleading switch point across the eccentricv track, its movement. in the opposite direction in nowise affecting. the situation of the leading. point.

DEIVLIN

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