US3440860A

US3440860A - Cyclic positioning mechanism

Info

Publication number: US3440860A
Application number: US565969A
Authority: US
Inventors: Erwin B Byam; John C Mcmurray
Original assignee: Textron Inc
Current assignee: JONES & LAMSON VERMONT CORP A CORP OF DE; Textron Inc
Priority date: 1966-07-18
Filing date: 1966-07-18
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29
Also published as: BE701511A; SE354428B; DE1627639A1; GB1136879A

Description

April 29, 1969 E. a. BYAM ETAL 3,449,860

CYCLIC POSITIONING MECHANISM Sheet Filed July 18. 1966 IITVENTOR Evuum B. Bqam John C. MaMurvaq ATTORNEYS A ril 29, 1969 E. a. BYAM ETAL 3,440,860

CYCLIC POSITIONING MECHANISM' Filed July 18. 1966 Sheet ,3 of s ET B. 62m

6 l 6 la INVENTOR E'vuum B,Bu am John C. McMuvvaq D2 f0 0M8 WWW ATTORNEYS United States Patent US. Cl. 72427 17 Claims ABSTRACT OF THE DISCLOSURE A mechanism for knocking a workpiece from a die by means of a pin adapted to be inserted in the die carried on a frame member where a first lever is pivotally mounted with respect to the frame and arranged to advance the pin into the die. A second lever is pivotal with respect to the frame and is operated upon by a drive means for pivoting the second lever and a third lever is pivoted to the frame and is in contact at opposite ends thereof with the first and second levers so that upon pivotal motion of the second lever the third lever moves said first lever to advance the knock-out pin.

This invention relates to positioning mechanisms arranged to cyclically operate on a positionable member and more particularly relates to such mechanisms which {nay operate at relatively high speeds with reduced backash.

Linkage mechanisms embodying the invention may be incorporated in many types of machines which cyclically operate to position a member which may be reciprocably moved in a guide means. An example of such member is the knock-out pin of a heading machine and the invention will be disclosed in such environment.

Heading machines, well known in the art, generally comprise a die member adapted to receive a workpiece in a die cavity, a gate carrying one or more punches adapted to form a portion of the workpiece, a knock-out mechanism arranged to knock the workpiece from the die cavity after a forming blow upon the workpiece and a transfer mechanism adapted to position a subsequent workpiece in or adjacent the die cavity prior to a subsequent stroke of the forming punch. The various mentioned mechanisms, the knock-out mechanisms, transfer mechanism and punch carrying gate are all operated in timed relation to effect a cycle of workpiece heading, knock-out and transfer. Such timing of the various mechanism is achieved through various elements, such as cams, connecting rods, levers, etc. As the speed of operation of a heading cycle increases to correspondingly decrease the time in each heading cycle, the backlash or clearance between the various mechanical components must be minimized or eliminated to decrease non-working time and, further, to decrease the impact and acceleration loads on the various parts which usually increase with increased speed of operation.

The present invention provides a new and improved mechanism which may be utilized as a knock-out assembly for a heading machine and which decreases the clearance or backlash between the operating parts thereof to enable higher speed operation without undue loading due to impact and acceleration on the parts, and which further reduces the noise level during operation due to the decreased backlash.

Accordingly, an object of this invention is to provide a new and improved motion transmitting mechanism having greatly reduced backlash.

Another object of this invention is to provide a new and improved knock-out assembly for a heading machine.

Another object of the invention is to provide a new and improved knock-out assembly for a heading machine which contributes to higher speed operation of the heading machine by reducing the backlash and clearance be tween the parts of the knock-out mechanism.

A further object of this invention is to provide a new and improved knock-out assembly for a heading machine which eliminates backlash therein when a knockout cycle is initiated.

A still further object of this invention is to provide a new and improved knock-out assembly for a heading machine which is easily adjustable to accommodate various size workpieces formed by the machine and the distance of the knock-out stroke without introducing backlash into the system.

These and other objects of the invention are achieved in one form thereof through the utilization of a biased lever which is actuated in timed relation of movement of the machine punches through a drive lever and rocker lever in such a manner that once operation of the drive lever is initiated no clearance or backlash exists in the system. More specifically, this is achieved through an arrangement wherein a knock-out lever and a drive lever have a motion transmitted therebetween by a rocker lever pivoted intermediate its ends which bear on both the knock-out lever and the drive lever. This arrangement is further adjustable to accommodate workpieces of various sizes and allow adjustment of the stroke of the knockout pin in accordance with the size of the workpiece.

The features of the invention which are believed to be novel are set forth with particularity and distinctly claimed in the concluding portion of this specification. However, the invention both as to its organization and operation together with further objects and advantages thereof may best be appreciated by reference to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is an elevation of a heading apparatus embodying the invention;

FIG. 2 is an end view of the apparatus of FIG. I seen from the right hand side thereof;

FIG. 3 is a view, partially cut away, seen in the plane of line 33 of FIG. 2, and showing the knock-out assembly in a knock-out position;

FIG. 4 is a view similar to FIG. 3 showing the knockout assembly in a relaxed position; and

FIG. 5 is a view of another lever system embodying the invention.

A heading apparatus in which the invention may be embodied is generally represented by the reference numeral 10 and comprises a base 11 having the frame 12 of the header mounted thereto. The apparatus includes a movable gate G carrying one or more punches arranged to act upon a workpiece in a die 62. A set of cams 13 and 14 which operate a workpiece knock-out assembly are mounted to a shaft 15 rotatably mounted to frame 12 by means of brackets 16. Shaft 15 is rotated in timed relation with the operation of the machine parts such as the punches, etc., in a manner well known to those skilled in the art. Cams 13 and 14 operate upon cam followers 17 and 18 rotatably mounted to a three-arm crank 19 which, in turn, is pivotally connected at 20 to a rod 21. When shaft 15 is rotated, cam 13 acts on follower 17 to pivot lever 19 counterclockwise about point 22 which extends rod 21 to the right, as viewed in FIG. 1. As cam 14 during the alternate portion of the cycle acts on cam follower 18, lever 19 is pivoted clockwise and retracts rod 21. As will hereinafter be explained, When rod 21 is retracted under the operation of cam 14, the knockout assembly is operated to knock-out a workpiece from a die. When lever 19 is under the operation of cam 13, rod 21 is extended, and the knock-out assembly is turned to a relaxed position.

The apparatus further comprises a drive pulley 23 mounted to a shaft 24 which is driven by a prime mover such as an electric motor, not shown, and all parts, including shaft 15, are operated in synchronism or timed relation to rotation of pulley 23 by means of suitable connecting devices.

Hereinafter the cams 13 and 14 will be referred to merely as a knock-out cam whose function is to rock a crank 26 having

arms

27 and 28 in fixed relation to each other on a shaft 29 carried by frame 12. The free end of arm 28 carries an adjustable link 30, as will hereinafter be explained.

Each of the

arms

27 and 28 is connected to

sleeve portions

32 and 33 disposed about shaft 29 and joined to each other by means of a bolt at 34. Rod 21 is pivotally connected to one end of arm 27 by a pin 35.

As more clearly shown in FIG. 3, link 30 may comprise a threaded shaft 36 received in the end of arm 28 and carrying at one end thereof a camming member 37 which acts against a nose 38 of a drive lever 39 pivoted to a shaft 40 carried by frame 12. Also pivotally mounted about shaft 40 is a knock-out lever 41, having a nose portion 42.

In accordance with one aspect of the invention, means are provided which may be adjusted to keep the backlash in the overall knock-out system to a minimum. This is highly desirable in high speed knock-out mechanisms, not only from the noise level but from the reduction of impact and acceleration load on the parts of the knock-out assembly.

A plate-like member 43 is mounted to frame 12 as by means of

bolts

44 and 45 and includes an elongated guide slot 46 therein which guidably receives a travelling member 47. Member 47 threadably engages a threaded shaft member 48 carried by member 43 so that upon rotation of shaft 48 member 47 will move axially along shaft 48 Within slot 46. When positioned along the length of shaft 48 member 47 may be locked to plate member 43 by means of nut 49 threaded to a stud portion 50 of member 47. Member 47 further carries a pivot-providing block member 51 which mounts a shaft 52. Pivotally mounted to shaft 52 is a rocker crank 53 having

nose portions

54 and 55 arranged to engage drive lever 39 and knock-out lever 41 on either side of shaft 40.

By means of the mechanism just described, the position of shaft 52 may be varied along the length of shaft 48 within the confines of slot 46.

An abutment stop for lever 41 is provided in the form of a bolt 56 threadably received in a nut-like member 57 in a bracket 57a on frame 12. Bolt 56 is locked in position by a lock nut 58. The end 59 of bolt 56 provides a stopping surface for knock-out lever 41 when it is rotated in the clockwise direction, and the position of bolt 56 in member 57 determines the limits of counterclockwise motion of knock-out lever 41.

In operation, when the knock-out cam retracts rod 21 crank 26 moves link 30 forward to engage drive lever 39 which is pivoted in a counter-clockwise direction and engages nose 54 of rocker 53 which is also pivoted in a counter-clockwise direction. Nose 55 of rocker 53 then engages knock-out lever 41 which is also pivoted in a counter-clockwise direction to the position shown in FIG. 3.

Nose 42 of knock-out lever 41 then engages and advances a plunger 60 in frame 12 to, in turn, advance a knock-out pin 61 in die 62 and knock-out a workpiece therein.

Movement of knock-out lever 41 to the position shown in FIG. 3 further advances a plunger 63 against the bias of a spring 64 so that when rod 21 is extended and link 30 withdrawn from drive lever 39, the energy stored in spring 64 will move knock-out lever 41 to itsrelaxed position as shown in FIG. 4.

In FIG. 4 the knock-out assembly is shown in the relaxed or retracted position, and further illustrates the range of backlash or clearance adjustment which may be achieved through the provision of rocker 53. As the member 47 is adjusted to the right (as shown in FIG. 4) the travel of knock-out lever 41 between a retracted position and a knock-out position is decreased.

This mechanism provides a very high degree of repeatability to a fixed point which is exemplified as the set position of plunger 60 (FIG. 3). Upon adjustment of the system for a predetermined stroke of lever 41, during cyclic operation of the lever system, lever 41 and, more specifically, contacting nose 42 thereof will always return to this fixed point at the end of the knock-out stroke. This is accomplished by predetermining the relationship of

levers

39 and 41 so that in the full knock-out position the lever 41 is set to a point to which it always returns at the end of a knock-out stroke. This alleviates the problems presented by over or under travel of a knock-out lever and reduces wear, chatter and backlash of the parts.

In order to adjust the knock-out stroke two parameters must be considered, the length of the workpiece to be knocked out of die 62, and the stroke of the knock-out lever. This adjustment is made by first setting the knockout lever 41 in the full knock-out position (as shown in FIG. 3) or spaced therefrom with a predetrmind minimum clearance. Lever 39 is then positioned in alignment with lever 41 to establish a relationship of the

levers

39 and 41 that will always bring lever 41 back to its set position when lever 39 is actuated. Member 37 is then located at nose 38 on lever 39 or with predetermined minimum clearance with respect thereto. At this time the edges of

levers

39 and 41 in contact with rocker lever 53 are in a straight line relationship or, otherwise stated, reside in a common plane in parallel relationship. In this relationship member 37 is located to set knock-out pin 61 at the face 62a of die 62 or, alternatively, the shoulder 61a of pin 61 is in engagement with die 62. With drive lever 39 and knock-out lever 41 aligned at the full knock-out position, the position of link 30 and member 37 will remain constant within the limit of manufacturing tolerances. Next, link 30 through rod 21 is brought to the low position on the knock-out cam, as exemplified in FIG. 4, so that it is backed oil? from drive lever 39. Holding spring 64 will now return knock-out lever 41 towards knock-out stop and abutment surface 59. A measured length of stock equivalent to that of a workpiece is inserted in die 62 against knock-out pin 61 and the knock-out stop bolt 56 is adjusted until it just touches knock-out lever 41. Nut 49 is then loosened and screw shaft 48 is turned to move member 47 and, more specifically, rocker lever 53 to a position to contact both knock-out lever 41 and drive lever 39, with knock-out lever 41 held against the stop.

Now, in operation, when member 37 is advanced and contacts drive lever 39, drive lever 39, rocker lever 53 and knock-out lever 41 are essentially rigid and the equivalent of a single lever, but with no backlash. When the lever 41 is initially set against plunger 60 and lever 39 is aligned therewith the end point of the stroke of lever 41 is established and during cyclic operation of the lever system,

lever 41 always terminates its knock-out stroke at this set point.

The foregoing adjustment is applicable to the machine as illustrated. On multiple station heading machines, the drive lever 39 could be actuated by rotating the shaft to which it is attached.

In this arrangement it may be seen that during the knock-out operation there is no backlash once the link 30, operated from the knock-out cam, contacts the drive lever 39 since rocker lever 53 simultaneously contacts both knock-out lever 41 and drive lever 39, and there is no clearance therebetween. This arrangement maintains the backlash in the overall knock-out assembly to a minimum which allows higher speeds of operation without objectionable noise levels, and minimizes the impact and acceleration loads on the part of the knock-out assembly.

Another embodiment of the invention is shown in FIG. 5 wherein a drive means in the form of a cam 70 is utilized to return a positioning lever 71 equivalent to the knock-out lever 41 to a retracted position. In this embodiment of the invention lever 71 normally acts upon a member 72 movable in a guide 73 in a frame 74. Lever 71 is pivoted to the frame at 75 and a drive lever 76 is pivoted to the frame at one end thereof at 77, and at the other end thereof pivotally carries a cam follower 78 which is driven by cam 70. Lever 71 is normally urged towards member 72 by means of a plunger 79 biased by a spring 80, and moves between the position shown, determined by an adjustable stop 81, and a position against face 81a. A rocker lever 82 is pivotally mounted to a block 83 which may be adjustably positioned in channel 84 on frame 74. Y

The operation of the mechanism shown in FIG. 5 will be apparent from the foregoing description and it need only be pointed out that in this arrangement the cam 70 retracts lever 71 from the positionable member 72 against the bias of spring 80. The initial adjustment of the mechanism of FIG. 5 is similar to that previously described, the primary difference in the mechanisms of FIGS.l-4 and FIG. 5 being that the drive stroke in one instance in used to advance the positioning lever while in the other instance it is utilized to retract the positioning lever.

It will further be noted that the adjustable rocker lever in both cases acts as a variable force multiplier dependent upon its position relative to the drive and positioning levers.

It may thus be seen that the objects of the invention set forth as well as those made apparent from the preceding description are efficiently attained. While a preferred embodiment of the invention has been set forth for purposes of disclosure other embodiments of the invention as well as modifications to the disclosed embodiment thereof which do not depart from the spirit and scope of the invention may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments and modifications to the disclosed embodiment of the invention which do not depart from the spirit and scope thereof.

We claim:

1. In a forming machine having a frame member, a die adapted to receive a workpiece for forming, a pin adapted to be inserted into said die to knock out a workpiece therefrom, a punch member adapted to form workpieces inserted in the die, a drive mechanism for reciprocating the punch toward and away from the die, cam means driven in timed relation to the punch and connecting means reciprocally driven by the cam means; a knockout pin operating assembly comprising first and second levers, said first and second levers having adjacent ends pivotally mounted to said frame member, said first lever being arranged to advance the pin into the die, said second lever being arranged to be pivoted by the connecting means, a third lever pivotally mounted to the frame intermediate the ends thereof, said third lever being in contact adjacent the ends thereof with said first lever and said second lever so that upon pivotal motion of said second lever by the connecting means said third lever moves said first lever to advance said pin.

2. The invention of claim 1 wherein the pivotal mounting of said third lever is movable on said frame to adjust its points of contact with said first lever and said second lever.

3. The invention of claim v1 further including a member slidably mounted to the frame, said third lever being pivotally mounted to said member.

4. The invention of claim 3 including guide means carried on said frame, said member being movably mounted on said guide means.

5. The invention of claim 4 wherein said guide means includes a threaded shaft, said member threadedly receiving said shaft and non-rotatably mounted to said guide means so that upon rotation of said shaft said member moves longitudinally along said shaft.

6. The invention of claim 1 further including means biasing said first lever toward said third lever.

7. The invention of claim 1 wherein said first lever and said second lever are pivotal with respect to a common axis.

8. A mechanism for knocking a workpiece from a die comprising a pin adapted to be inserted in the die, a frame member, first and second levers, said first and second levers having adjacent ends pivotally mounted to said frame member said first lever being arranged to advance said pin into the die, drive means for pivoting said second lever and a third lever pivotally mounted to the frame, said third lever being in contact at opposite ends thereof with said first lever and said second lever so that upon pivotal motion of said second lever said third lever moves said first lever to advance said pin.

9. The mechanism of claim 8 further including means for adjusting the position of said third lever with respect to said first lever and said 'second lever.

10. The mechanism of claim 9 wherein said first lever and said second lever are pivotally mounted about a common axis and said third lever contacts said other levers on opposite sides of said axis.

11. An apparatus for controlling the position of a member in a defined guide means comprising a frame member, first and second levers, said first lever being pivoted to said frame member at one end thereof, the other end of said first lever adapted to operate on said member, biasing means acting upon said first lever intermediate the ends thereof and arranged to pivot said first lever in a first direction, a second lever pivotally mounted to said frame member at one end thereof adjacent the pivoted end of said first lever, a third lever pivotally mounted intermediate the ends thereof to said frame and having its ends bearing on said first and second levers, and drive means for acting on the free end of said second lever to move said second lever about its pivot point and cause said third lever to produce pivotal motion of said first lever against the force of said biasing means.

12. The apparatus of claim 11 wherein said first and second levers have a common pivotal axis.

13. The apparatus of claim 11 wherein the third lever is movable on said frame to adjust its points of contact on said first and second levers.

14. A variable stroke positioning apparatus with accurate repeatability to a fixed endpoint comprising a rigid member, a first lever pivoted at one end to said rigid member, the other end of said first lever adapted to operate on a point whose spatial relationship to said rigid member is fixed, a second lever pivotally mounted at one end to said rigid member adjacent the pivoted end of said first lever, a third lever pivotally mounted at a point intermediate its ends with respect to said rigid member, said third lever being spaced in relationship to said first and second levers so that the ends of said third lever bear against said first and second levers, and drive means for acting on the other end of said second lever to move said second lever about its pivot point and cause said third lever to produce pivotal motion of said first lever toward said fixed point.

15. The apparatus of claim 14 wherein said first and second levers have a common pivotal axis.

16. The apparatus of claim 14 wherein said third levers pivot point with respect to said rigid member is adjustable so as to vary the stroke of said first lever.

17. The apparatus of claim 14 wherein said first lever is biased in a direction away from said fixed point.

References Cited UNITED STATES PATENTS 3,112,660 12/1963 Hoyt 10-12 X Carlson l0ll X Carlson l0l1 X Maistros 72427 X Hoyt 1011 X Nebendorf 72427 X McClellan 1025 X Van De Meerendonk 72427 X CHARLES W. LANHAM, Primary Examiner.

US. Cl. X.R.