US3588396A - Rotary stepping programmer with improved camming means - Google Patents

Abstract

A ROTARY STEPPING PROGRAMMER FOR CONTROLLING A PLURALITY OF MACHINE OPERATIONS IN A PREDETERMINED SEQUENCE, COMPRISING: A FRAME, A MOTOR SECURED TO THE FRAME, A PLURALITY OF SWITCH MEANS MOUNTED ON THE FRAME FOR CONTROLLING THE MACHINE OPERATIONS, FIRST CAM MEANS FOR ALTERNATELY ACTUATING AND DEACTUATING THE SWITCH MEANS, SECOND CAM MEANS FOR PERIODICALLY ROTATING THE FIRST CAM MEANS, AND MEANS FOR CONNECTING THE SECOND CAM MEANS TO THE MOTOR.

Description

United States Patent I lnventor [72] Gary D. Fredell East Moline, 1]]. [21] Appl. No. 820,851 [22] Filed May 1, 1969 [45] Patented June 28, 1971 [73] Assignee Gul1& Western lndustries,1nc.

[54] ROTARY STEPPING PROGRAMMER WITH IMPROVED CAMMING MEANS 8 Claims, 8 Drawing Figs. I

[52] 11.8. C1. 200/38, 200/153, 74/569 [51] Int. Cl. H0111 7/08, H0111 43/ 10 501 Field ofSearch ..200/38 0,

38 (Cl), 38, 153.11, 153.l 2,153.13, 153.19, 665 a [56] References Cited UNIT ED STATES PATENTS 2,174,331 9/1939 Schroeder 200/38(C1) 2.980,?70 4/1961 Nabstedt ...200/l66(SD)UX 3,177,310 4/1965 Deeken 200/38(C1) 3,253,108 5/1966 Mumma 200/38(C) 3,283,090 11/1966 Hausser et a1. ZOO/38X 3,330,917 7/1967 Grundfest 200/38 3,377,446 4/1968 Davis 200/38(C) Primary Examiner-Robert S. Macon Assistant Examiner-J. R. Scott Attorney-Meyer, Tilberry and Body ABSTRACT: A rotary stepping programmer for controlling a plurality of machine operations in a predetermined sequence, comprising: a frame; a motor secured to the frame; a plurality of switch means mounted on the frame for controlling the machine operations; first cam means for alternately actuating and deactuating the switch means; second cam means for periodically rotating the first cam means; and means for connecting the second cam means to the motor.

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sum 2 OF 3 I ENTOR GARY 0. EDELL BY Maya, 7:16am; 8 Bad;

ATTORNEYS PATENTEUJUH28197! 3588396 SHEU 3 OF 3 fig? INVENTOR. GARY D. FREDELL fie mm, a M,

ATTORNEYS ROTARY STEPPING PROGRAMMER WITI-I IMPROVED CAMMING MEANS This application pertains to the process control art and, more particularly, to an improved rotary stepping programmer.

The invention is particularly applicable for controlling a plurality of machine operations in a predetermined sequence and will be described with reference thereto; however, it will be appreciated that the invention has broader applications and is suitable for use with industrial control systems in general.

In view of the advances over the past decade in automatic machine operation, there has been an ever increasing demand for programmers which are both versatile and inexpensive. One of the approaches taken to meet this demand has been in the form of a stepping switch. These devices usually include a motor, a cam structure rotatably driven by the motor and adapted to actuate a plurality of switches in a programmed sequence for controlling the operation ofa machine.

Numerous methods have been employed in commercially available stepping devices to control the sequential actuation and deactuation of the switches by the cam. One such device employs a breakout-type cam configuration. In this structure an elongated shaft has a plurality of radially, outwardly extending projections which are adapted to be easily broken away to define a cam profile. A programmed cam will thus have projections and recesses which actuate and deactuate these switches respectively. Another type of commercially available device makes uses of an elongated shaft having a plurality of circumferentially spaced holes about the periphery thereof. Pins are then releasably inserted into some of these holes to define projections which are capable of actuating the switches. Those portions of the shaft which do not contain pins constitute depressions in the cam profile, thereby causing the switches to be deactuated.

The above-described stepping switches possess a variety of problems which greatly detract from their usefulness. Those devices which employ the breakouttype cam lack the versatility required of a programmer. Being more specific, once a cam profile has been established by breaking away certain projections, the cam may only be used to perform this single program. If it is later determined that minor adjustments in the program are required, an entirely new cam must be designed, since it is impossible to replace projections once they have been broken away. This drawback has been overcome in the pin and drum type programmer, and as such this device possess adjustability Unfortunately, the pin and drum type programmer is deficient in another respect. Assuming in a given program it is necessary to maintain the switch in the actuated position during 90 percent of the drums rotation, it will be necessary to insert, depending upon the particular device, a large number of pins into the drums surface. Since these programmers contain'a plurality of switches, it can be readily seen that in a particular program as many as 200 or 300 may be required in order to define a complete program. Therefore, it not only takes a great deal of time to set up the program, but also requires that a large inventory of pins be kept on hand to accomplish this task.

The present invention contemplates a new and improved apparatus which overcomes all of the above referred problems and others by providing a rotary stepping programmer which may be easily, rapidly, and adjustably programmed.

In accordance with the present invention there is provided a rotary stepping programmer, comprising: a frame; a motor secured to the frame and adapted to be energized by an external source; switch means mounted on the frame for controlling the operations of a machine in accordance with a predetermined program; first cam means for alternately actuating and deactuating the switch means; the first cam means rotating about an axis fixed with respect to the switch means; second cam means for periodically rotating the first cam means; the second cam means being rotatable about a longitudinal axis substantially parallel to the axis of the first cam means; and means for connecting the second cam means to the motor, whereby when the motor is energized the second cam means rotates causing the first cam means to periodically rotate thereby alternately actuating and deactuating the plurality of switch means.

The principal object of the present invention is to provide an improved rotary stepping programmer which may be easily and rapidly programmed.

Another object of the present invention is to provide an improved rotary stepping programmer wherein adjustments to existing programs may be easily and rapidly carried out.

A further object of the present invention is to provide an improved rotary stepping programmer which does not require the addition of new components in order to be reprogrammed.

A still further object of the present invention is to provide an improved rotary stepping programmer of novel design which requires only a single pin to actuate a switch and a single pin to deactuate a switch.

Yet another object of the present invention is to provide an improved rotary stepping programmer which eliminates the need for maintaining a large inventory of parts in order to establish and adjust a program.

An additional object of the present invention is to provide an improved rotary stepping programmer which is economical to manufacture.

These and other objects and advantages will become apparent from the following description used to illustrate the preferred embodiment of the invention when read in connection with the drawings in which:

FIG. 1 is a front elevational view, partly broken away, of a rotary stepping programmer according to the preferred embodiment of the present invention,

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged cross-sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged cross-sectional view taken along line 4-4 of FIG. 1;

FIG. 5 is an enlarged cross-sectional view taken along line 5-5 of FIGS. 2 and 4;

FIG. 6 is an enlarged side elevational view of an elongated pin used in conjunction with the present invention;

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 6; and

FIG. 8 is an enlarged cross-sectional view, partly broken away of the cam means shown in FIG. 2.

Referring now to the drawings wherein the showings are for the purpose of illustrating the preferred embodiment of the invention only and not for the purpose of limiting same, FIG. 1 shows a rotary stepping programmer, designated generally by the reference letter A, comprising as its basic components: a frame B; a motor C; switch means D; cam means E; and actuator means F.

As best shown in FIGS. 1 and 2, the frame B includes a bottom wall 10, upwardly extending sidewalls l2 and top walls 14. The motor C is disposed on the outer face of one of the sidewalls 12 and secured thereto by means of screws 16. It is to be appreciated that the motor C may take many forms depending upon the particular application to which the programmer A is to be put such as a step motor or dual-speed motor; however, in accordance with the preferred embodiment of the present invention it takes the form of a synchronous motor. The motor C is adapted to be connected to an external power source (not illustrated) by leads 18.

In accordance with the present invention there is provided switch means D which may take many forms; however, in the preferred embodiment it takes the form of a miniature switch 20. A plurality of these switches 20 are carried by the programmer A, and the number of switches used will vary depending upon how many operations it is desired to control. Each switch 20 is secured to a substantially vertical cam support member 22 by means of screws 30. An insulator 32 is provided intermediate the switch 20 and the cam support member 22. The cam support member 22 includes an outwardly extending mounting bracket 34 which is secured to the top walls 14 of the frame B by screws 36. In this manner, the switches are supported above the top walls 14 by a portion of the cam support member 22, while the remaining portion of the support member extends downwardly below the top walls and into the enclosed area defined by the frame B.

Extending outwardly from the bottom of the switch 20 is a spring biased plunger 38 which controls the actuation and deactuation of the switch. The switch further includes contacts 40 which extend outwardly from the switch 20 and are adapted to be connected by leads (not illustrated) to a machine (not illustrated) whose operation is to be controlled by the programmer A. The contacts 40 may be connected to the leads in one of two ways, to provide either a normally closed switch or a normally open switch depending upon the nature of the operation which is being controlled by the particular switch. Suspended below the switch 20 and pivotally connected thereto, is an actuating lever 42 having a follower wheel 44 rotatably mounted on its free end. The actuating lever 42 is in contact with the spring biased plunger 38, as such, when the lever is caused to be moved in an upward direction toward the switch 20, it will depress the plunger, thereby actuating the switch.

Movement of the actuating lever 42 is controlled by the cam means E which includes a cylindrical portion 50 having a hub 52 integral therewith. A shaft 54 extends perpendicularly outward from the lowermost end of the cam support member 22 and cylindrical portion 50 is coaxially disposed about the shaft. The hub 52 is rotatably mounted on the shaft 54, thereby permitting the cylindrical portion 50 to rotate about the shaft. Extending radially outward from the hub 52 is a plurality of spokes 56, whose purpose and operation will be described in more detail later. The circumferential surface of the cylindrical portion 50 is configured to define a cam profile having a plurality of radially, outwardly extending projections 58 and equal number of depressions 60 disposed intermediate the projections. Upon rotation of the cam means E, the actuating lever 42 is either biased onto the radially outermost surface of the projections 58 or into the depressions 60 in order to actuate and deactuate the switch 20 respectively. The radially outermost surface of the projections 58 are provided with a recess 62, as seen in FIG. 8, which is configured to receive a portion of the follower wheel 44. As the cam means E rotates, the follower wheel 44 will be releasably retained in the recess 62 whenever the actuating lever 42 is biased onto the radially outermost surface of the projection 58.

In accordance with the present invention the cam means E further includes a detent means for releasably retaining the cam means in a preselected position on the shaft 54 of the cam support member 22. As best shown in FIGS. 4 and 5, the detent means includes a cylindrical sleeve 64 which is disposed intermediate the shaft 54 and the cylindrical portion 50. The sleeve 64 is secured to the cylindrical portion 50 for rotation therewith, and the inner surface of the cylindrical sleeve 64, namely the surface adjacent the shaft 54, is provided with a plurality of equally spaced disc-shaped depressions 66. A pair of radial slots 68 are included in that portion of the shaft 54 which is circumscribed by the cylindrical sleeve 64 and have disposed therein a ball 70 which is biased radially outward by a spring 72. The balls 70 are dimensionally capable of being biased into the disc-shaped depressions 66 to releasably retain the cam means E in a variety of preselected positions on the shaft 54.

As best shown in FIG. 5, a plate 74, carried by the shaft 54 near its outermost edge prevents the longitudinal displacement of the cam means E relative to the shaft. The plate 74 is maintained in the aforementioned position by a spring clip 76 which is received in a groove on the outermost end of the shaft 54.

Reference is now made to FIGS. 1 and 2, where in accordance with the present invention there is provided an actuator means F which may take a variety of forms. However, in the preferred embodiment it takes the form of a elongated drive shaft 80 and a plurality of cylindrical drums 82 axially spaced on the shaft for rotation therewith. The end points of the drive shaft 80 are supported in bearings 84 which are carried by the sidewalls 12 of the frame B. One end of the drive shaft 80 passes through a sidewall 12 and is connected to the motor C by a clutch means 86, whereby when the motor is energized the drive shaft rotates. The cylindrical drums 82 are coaxially secured to the drive shaft 80 by a key 88 which axially extends throughout the length of the shaft. A pair of sleeves 90, which are secured to the drive shaft 80 and disposed on either side of each drum 82, prevent the axial movement of the drum relative to the shaft.

In accordance with the present invention there is provided releasable pin means which may take many forms, such as a pin which is magnetically retained on the drum 82; however, in the preferred embodiment the pin means comprises a plurality of circumferentially spaced channels 92 extending radially inward from the surface of the drum 82 and elongated pins, designated generally by reference numeral 94, adapted to be releasably received in some of the channels. As shown in FIG. 6 each pin 94 includes a base portion 96 which is inserted into the channel 92, a stop portion 98, which establishes the depth to which the base portion may be inserted, and a driving portion 100 for engaging the spokes 56 of the cam means E. The pins 94 extend radially outward from the surface of the drum 82 and are in periodic driving engagement with the spokes 56 of the cam means E, whereby when the motor C is energized the drums rotate causing the pins to periodically drive the cam means, thereby sequentially actuating and deactuating the switches 20.

Referring now to FIGS. 1 and 2, wherein there is illustrated a rotary stepping programmer A whose operation will now be described in detail. For purposes of this explanation it will be assumed that the switches 20 are in a normally open position, and, as such, have not been actuated by the operation of the programmer.

A program is established by inserting pins 94 in the channels 92 of the cylindrical drums 82. These pins are located at preselected points on the circumference of the drums 82 and indirectly control the actuation and deactuation of the switches 20. Program revisions can easily and rapidly be carried out by merely changing the circumferential location of a given pin 94.

Upon completion of the programming operation the motor C is energized, and drives through clutch means 86 to rotate the elongated drive shaft 80 at a constant rate of speed. Rotation of the drive shaft 80 causes the cylindrical drums 82 to also rotate at a constant speed. At a preselected point in drum rotation, the driving portion 100 of a pin 94 will come into driving engagement with a spoke 56 of the cam means E. The continued rotation of the drum 82 will, as a result of the aforementioned driving engagement, cause the cam means E to be rotated in a direction opposite to that in which the drum is rotating. As the cam means E rotates, the follower wheel 44 will trace the contour of the cylindrical portion 50, and will move radially outward from a depression 60 to the outermost surface of a projection 58. In so moving, the actuating lever 42 will depress the spring biased plunger 38 to actuate a switch 20. Having reached the aforementioned position, the follower wheel 44 will be releasably retained in recess 62, thereby holding the switch 20 in the actuated condition until the cam means E is once again rotated.

The shaft 80 and hence the drum 82, continues to rotate. At a second preselected point in drum rotation, another pin 94 will be brought into driving engagement with a spoke 56 of the cam means E. Further drum rotation will cause this latter pin 94 to similarly rotate the cam means E in a direction opposite to that in which the drum 82 is rotating. As the cam means E rotates for the second time, the follower wheel 44 will once again trace the contour of the cylindrical portion 50, and the wheel will now be released from its position within the recess 62 and be biased downward into a depression 60. In so moving, the actuating lever 42 will pivot away from the switch 20,

thereby permitting the plunger 38 to be biased outward in order to deactuate the switch. The cam means E will be releasably retained in this position by the detent means. More specifically, the balls 70 will be biased into the disc-shaped depressions 66 to prevent unintentional rotation of the cam means 80.

Although the above operation has been described with reference to only two pins, it is to be appreciated that any number of pins may be spaced about the circumference of a given drum 82. The number and location of pins being determined by the specific requirements of a particular program. It can therefore be seen, that each pin will cause the switch to either be actuated or deactuated, depending upon the state which the switch is in immediately prior to further rotation by the pin. it is to further be appreciated that any number of drums 82 and switches 20 may be employed in order to accomplish the programming of a particular mechanism.

In view of the foregoing, it can be seen that the present invention provides an improved rotary stepping programmer which may be easily and rapidly programmed at a minimum of cost. Furthermore, program changes may be carried out without the replacement of major components by merely relocating the position of the pins 94.

lclaim:

l. A rotary stepping programmer for controlling a plurality of machine operations in a predetermined sequence, comprising: a frame; a motor secured to said frame and adapted to be energized by an external power source; a plurality of switches mounted on said frame and adapted to be electrically connected to said machine; a plurality of cam means having an axis of rotation fixed with respect to each of said switches for alternately actuating and deactuating said switches upon rotation of said cam means; said cam means including a cylindrical portion having a circumferential surface configured to define a cam profile having equally spaced projection and depression means and a spoked portion connected to said cylindrical portion; said switches including an actuating lever biased to be in contact with said circumferential surface; actuator means carried by said frame for rotation about a longitudinal axis substantially parallel to the axis of said cam means; removable pin means disposed about the periphery of said actuator means and in predetermined periodic driving engagement with said spoked portion for rotating said cam means; and means for connecting said actuator means to said motor, whereby when said motor is'energized said actuator means rotates causing said pin means to periodically drive said plurality of cam means thereby alternately actuating and deactuating said switches.

2. The rotary stepping programmer of claim 1, further including a plurality of cam support members, each of said members being secured to a respective switch and each of said cam means being rotatably carried by said member.

3. The rotary stepping programmer of claim 2, wherein said cam means further includes a detent means for releasably retaining said cam means in a preselected position on said cam support member.

4. The rotary stepping programmer of claim 1, wherein said circumferential surface comprises a plurality of projections and depressions at equally spaced intervals, whereby upon rotation of said cam means said actuating lever is alternately biased onto the radially outermost surface of said projections and into said depressions to either actuate or deactuate said switch respectively.

5. The rotary stepping programmer of claim 4, wherein the radially outermost surface of said projections includes a recess and said actuating lever includes a rotatable follower wheel, whereby said wheel is releasably retained in said recess when said actuating lever is biased onto said projections.

6. The rotary stepping programmer of claim 1, wherein said actuator means comprises an elongated drive shaft and a plurality of axially spaced, cylindrical drums concentrically mounted on said drive shaft for rotation therewith.

7. The rotary stepping programmer of claim 6, wherein said pin means comprises a plurality of circumferentially spaced channels extending radially inward from the surface of said cylindrical drums and at least one elongated pin releasably received in one of said channels, said pin extending radially outward from the surface of said drum and in periodic driving engagement with the spoked portion of said cam means.

8. A rotary stepping programmer, comprising: a frame; a motor secured to said frame and adapted to be energized by an external source; switch means mounted on said frame for controlling the operations of a machine in accordance with a predetermined program; first cam means having equally spaced projection and depression means for alternately actuating and deactuating said switch means; said first cam means rotating about an axis fixed with respect to said switch means; second cam means for predeterminably periodically rotating said first cam means; said second cam means being rotatable about a longitudinal axis substantially parallel to the axis of said first cam means; and means for connecting said second cam means to said motor, whereby when said motor is energized said second cam means rotates causing said first cam means to periodically rotate thereby alternately actuating and deactuating said plurality of switch means.

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