US2879989A - Die stop mechanism - Google Patents

Description

INVENTOR. fias'fiqy WM I 2 Sheets-Sheet 1 .7 .flace.

I BY

B KRASBERG DIE STOP MECHANISM March 31, 1959 Filed Nov 23 1955 March 31, 1 959 B. KRASBERG 2,879,989

DIE STOP MECHANISM Filed Nov. 25, 1955 2 Sheets-Sheet 2 HIHIIIIIIIII United States Patent DIE STOP MECHANISM Bruce Krasberg, Winnetka, Ill.

Application November 23, 1955, Serial No. 548,619 4 Claims. (Cl. 20-132 This invention relates to a die mechanism, and more particularly to a stop mechanism adapted for use with punching, stamping and other types of die mechanisms for accurately positioning the work piece to be operated upon. In accordance with conventional punching practice, a punch or other tool carried by a reciprocating head reciprocates in registered openings in a complementary die and in a stripper plate carried above the die. The work piece, generally a sheet metal strip, is fed beneath the stripper plate, or preferably through a channel therein, to position the strip and to prevent the same from being lifted up by the punch or other tool.

In order that the sheet metal strip or other work piece may be positioned properly for punching or stamping by the punch or other tool there is generally provided a stop mechanism engageable with a previously punched or stamped portion of the strip or other work piece. Such stop mechanisms usually include a pivoted stop lever or rocker arm having an angularly disposed finger or pin at one end thereof which is engageable in the previously punched or stamped portion of the strip or other work piece in order to stop the work piece in its proper position. In order to operate satisfactorily, the lever or rocker arm must be capable of pivotal movement in a plane substantially perpendicular to the plane of the work piece. In addition to that, the stop lever or rocker arm should be pivotable or movable a limited amount in the direction of movement of the strip or other work piece to avoid tearing thereof when the work piece is stopped by the stop finger or pin on the stop lever. Heretofore, it generally has been found necessary to use two separate springs to bias the stop lever for the up and down pivotal movement and to bias the stop lever against the movement of the strip or other work piece.

Formerly, each job of a dilferent size generally necessitated the provision of a special type or size of stop lever, and it has not always been easy to change from one type or size to another. In R. Krasberg Patent No. 2,610,686, issued September 16, 1952, and entitled Automatic Stops for Dies, there is disclosed an improved stop mechanism wherein a lever arm of only one size, or of a limited number of sizes, is readily positioned for use with jobs of different sizes. As disclosed in said R. Krasberg patent, it is a simple job to adapt a single stock size, or one of a small number of stock sizes, of lever to a job of a given size. However, once a lever has been so adapted, it is generally limitedthereafter to use with a.job of that particular size.

This invention contemplates the provision of a stop mechanism having all of the advantages of the stop mechanism disclosed in the aforesaid R. Krasberg patent, with the additional advantageous feature that a single lever can be used over and over in jobs of diflierentsizes. Speaking more generally, this invention contemplates the provision of a stop mechanism having all of the advantages of the aforesaid patent, and having an even greater ease of installation.

. 34 are passed to securethe bracket 24 to the side of the:

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It is, therefore, an object of this invention to provide a die stop mechanism of the utmost simplicity in installation.

It is a further object of this invention to provide a die stop mechanism which is readily used for jobs of varying sizes, and which is not limited to a job of a particular size after it has once been placed in use.

More specifically, it is an object of this invention to provide a die stop mechanism wherein a single spring means is utilized for biasing the stop lever for up and down pivotal movement, for biasing the stop lever against the movement of the workpiece, and for retaining the ,stop lever in adjusted position.

Another object of this invention is to provide an improved spring for effecting the last named object.

Yet another object of this invention is to provide a die stop mechanism which is readily installed and which need not be recessed into the stripper plate.

Specifically, it is an object of this invention to provide a die stop mechanism having a universal bracket for mounting either on the side or on the top of the stripper plate.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. l is a top plan view showing the stripper plate and stop mechanism;

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1 and showing the punch and tappet mechanism;

Fig. 3 is an enlarged sectional view taken along the line 3-3 of Fig. 2 and showing the pivotal mounting for the stop lever;

Fig. 4 is an exploded perspective view of the stop lever and its mounting;

Fig. 5 is an enlarged perspective view of the pivotal mounting bracket receiving the stop lever;

Fig. 6 is aside view generally similar to Fig. 2 and showing a modification of the invention;

Fig. 7 is a fragmentary top. view showing the universal bracket of the modification;

Fig. 8 is a vertical sectional view taken along the line 8-8 in Fig. '6 and showing one end of the universal bracket; and

' Fig. 9 is a perspective view of the universal bracket.

Referring now in greater particularity to the figures, and first to Figs. 1 and 2 for a general understanding of the invention, there will be seen portions of a punch presscomprising the usual reciprocating tool head 10 carrying a punch 12. A die block 14 is suitably mounted beneath the tool head on a bed plate (not shown) according to conventional practice. The die block is provided with an aperture which is complementary in cross section to the punch 12, which is shown herein by way of example as being circular in cross section. A stripper 16 is suitably ain'xed to the top of the die block 14, and is provided with an undercut channel 18 through which a work piece in the form of a sheet metal strip 20 is passed in timed relation with the movement or reciprocation of the tool head 10.

The die stop mechanism is generally identified by the numeral 22 and is mounted on the side of the stripper 16 by means of a bracket 24 which is shown in detail in Fig. 5. Reference also should be had to Figs. 1, 2 and 3 for a description of this bracket, which will be seen to be generally channel-shaped having parallel side walls or flanges 26 connected by a transverse bottom wall or web 28. The side walls or flanges26 are provided with right-- angularly disposed and outwardly directed ears 30. These ears are provided with apertures 32 through which bolts 3 stripper, it being understood that bolts 34 are threaded into suitable, tapped apertures in the side of the stripper.

The die stop mechanism 22 further includes a pivotally mounted bracket 36. This bracket is generally channelshaped throughout its length including side walls or flanges 38 and a top wall or web 40. Portions of the side walls or flanges 38 are bent over at either end to form opposed pairs of flanges 42 and 44. The side walls or flanges 38 are provided with depending ears 46 having apertures 48 for receiving a pivotal mounting pin 50 which also is passed through aligned apertures 52 in the flanges 26 of the fixed bracket 24. A cotter pin 54 or the like is passed through a transverse hole 55 in the end of the pin to hold the same in its installed position. The pin is illustrated as having a head 56 which also serves to hold the pin in installed position, but it will be understood that the pin could be a straight pin and could be held in place by other means such as knurling the ends of the pin after insertion, by peening over the ends, or by any other suitable or known means.

A stop lever 58 is carried by the pivotal bracket 36 and is generally square or rectangular in cross section so as to be received non-rotatably between the flanges 38 and web 40 where it is held in place by the ears or lugs 44. The lever 58 may be straight, but preferably has an angularly disposed operative end as illustrated at 60. A downwardly extending pin or finger 62 is suitably affixed to, or formed integral with, the remainder of the lever 58 and extends downwardly through an opening 64 in the top of the stripper 16 for cooperative engagement with the work piece 20. For purposes of illustration the pin or finger 62 and cooperating aperture 64 both have been shown as circular in cross section, although it will be appreciated that other shapes could be used.

The height of the flanges 38 of the pivoted bracket 36, and the placing of the pivot pin 50 in the downwardly projecting or depending ears 46 positions the lever 58 so that it lies above the stripper 16. Accordingly, the stripper need not be recessed or interrupted except for the relatively small opening 64, and for an opening 66 permitting passage of the tool or punch 12. The pivoted bracket 36 is not quite as wide as the space between the flanges 26 of the fixed bracket as readily may be seen in Fig. 3. Thus, by making the apertures 48 slightly larger in diameter than the pin 50, the pivoted bracket is enabled to move or pivot slightly in a plane parallel to the work piece or strip 20. in addition to this, the stop lever or rocker arm 58 is not gripped by the pivoted bracket 36, but fits slidably therein so that the position of the stop finger or pin 62 readily can be adjusted transversely of the work piece or strip 20 simply by sliding it longitudinally in the bracket.

The die stop mechanism further includes a spring 68 which serves the triple function of biasing the lever or rocker arm 58 about the pivot pin, biasing the pin or finger (It against the direction of movement of the strip or work piece 20, and frictionally retaining the lever or rocker arm against longitudinal movement in the pivotal bracket 36 in adjusted position. This spring 68 includes a coiled portion 70 which is coiled about the pivot pin 50. A tail '72 extends integrally from the coil portion 70 and abuts the web 28 of the fixed bracket 24. From the other end of the coil, the spring extends outwardly away from the stripper 16 and diagonally across the lever arm or rocker 58 at a relatively shallow angle as shown at 74. This angled portion 74 normally lies parallel to the flange 38 of the pivoted bracket 36 and substantially in contact therewith before insertion of the lever arm or rocker 58. From the portion 74, the spring angles diagonally in the opposite direction across the pin 58 and still farther away from the stripper 16 as illustrated at 76. This portion '76 may form a somewhat sharper diagonal angle with the lever arm 58 than the portion 74 does, although this is not necessarily true. The diagonal portion 76 i m n ted. in a e ersely directed portion 78 extending transversely at right angles across the pin 58, and then upwardly as at 80 at right angles to both the lever 58 and to the transverse portion 78. When the lever or rocker arm 58 is inserted through the bracket 36, the spring portion 74 is moved away from the adjacent flange 38 of the pivoted bracket into the diagonal position shown, thus imposing a transverse loading on the spring which causes the lever or rocker arm 58 to be pivoted slightly in a plane parallel to the plane of the strip 20 with the depending pin or finger 62 moving slightly upstream or against the direction of motion of the work piece or strip 20, which direction of motion is toward the lower part of Fig. 1 from the upper part thereof as indicated by the arrows. The spring is also loaded so as to pivot the pivoted bracket 36 and the lever or rocker arm 58 in a clockwise direction as illustrated in Fig. 2 to bring the pin or finger 62 into engagement with the strip or work piece 20. This dual loading of the spring 68 causes the portions 78 and 80 to engage the sides of the lever arm or rocker arm 58 aggressively, thereby frictionally locking the lever or rocker arm 58 in longi' tudinally adjustable position. The frictional resistance can be overcome by pushing or pulling on the lever or rocker arm 58 to adjust the positioning thereof transversely of the strip 20.

The clockwise biasing of the lever arm by the spring causes the depending pin or finger 62 to tend to extend into openings or depressions formed in a strip or work piece 20 by the punch or tool 12. This tendency is overcome periodically to allow movement of the strip by a tappet 82 secured on the side of the tool head 10 by means such as one or more bolts 84. The tappet 82 comprises a spring metal strip and has a curved lower end or toe 85 which is engageable with the outer end of the pivoted bracket 36 to pivot the same in a counterclockwise direction upon lowering of the tool head 10 for a punching or forming operation. It will be understood that the lateral or transverse spring biasing of the lever or rocker arm 58 causes it to give slightly with the strip or work piece 20 when encountering a formed aperture 86 therein to stop the strip accurately in position without tearing or marring the same. Consequently, when the finger or pin 62 is subsequently raised from within the aperture in the strip by the depression of the outer end of the bracket 36 when engaged by the tappet 82, the transverse or lateral spring biasing of the lever or rocker arm 58 causes the same to move in a counterclockwise direction as shown in Fig. 1 through a small arc to move the depending pin or finger 62 back against the direction of motion of the strip 20. Accordingly, when the tappet is raised along with the tool head, the depending pin or finger engages the top of the strip and slides along the top of the strip. The finger then drops into the recently formed aperture 86 under the influence of the spring 68 and engages the trailing edge thereof accurately to arrest movement of the strip.

With the construction as heretofore shown and described it is unnecessary to recess the stripper plate for mounting the stop mechanism. However, the stop mechanism bracket must be mounted on the side of the stripper. There are times when it is not desirable to mount a bracket on the side of a stripper plate, and in accordance with that thought there is provided a preferred form of the bracket as shown in Figs. 6-9.

In the embodiment of the invention as shown in Figs. 6-9 most of the parts remain identical with those previously described, and others are analogous to those previously described. In order to avoid prolixity of description similar numerals have been utilized with the addition of the suflix a. Specific reference therefore will be made only to new or modified parts.

Specifically, the bracket 24a partakes of many of the characteristics of the bracket heretofore shown and described, including the side walls or flanges 26a and the interconnet ting bight comprising the transverse bottom wall or web 28a. The bracket also includes the laterally extending ears 30a having the apertures 32a therein for receiving attachment bolts or the like. The side walls or flanges 26a again are provided with apertures 52a for receiving the pivot pin 50a. The bracket also is provided with a plate 88 secured to the transverse bottom wall or Web 280 by suitable means such as spot welds 90. The plate extends laterally substantially coterminously with the ears 30a to provide horizontal mounting cars 92. The cars 92 are provided with apertures 94 which receive bolts 96 tapped into the top of the stripper 16a to support the stop mechanism on top of the stripper. Alternatively, the bracket 24a can be mounted on the side of the stripper by means of bolts (not shown) passed through the apertures 32a in the ears 30a in the fashion described with regard to the previous embodiment of the invention.

The pivotally mounted bracket 36a is pivotally secured in the mounting bracket in the manner previously described, and the die stop 58a is secured therein by the spring 68a. It is to be understood that the die stop additionally could be secured in the manner taught in the aforesaid R. Krasberg Patent No. 2,610,686 if it should be so desired. The pin or finger 62a generally is made of somewhat greater length when the stop mechanism is mounted on top of the stripper than it is when mounted on the side. It will be obvious that this pin or finger has to be sufliciently long to extend through the opening 64a into engagement with the strip 20a for penetration into punched openings or the like therein. The stripper is supported on the die block 14a, as will be obvious, and the die block may rest on a bed plate 98.

The tool head a is provided with a tappet 82a for operating or retracting the stop lever. The punch mechanism has been omitted from the tool head for clarity of illustration. The tool head carries an extension or projection 84a in the present instance, and the tappet comprises a bolt threaded through this projection, and preferably having a jam nut 100 threaded on the upper end thereof. The lower end of the tappet bolt preferably comprises a round or button head 85a for engagement with the tail of the stop lever to retract the finger 62a when the strip a is to be advanced.

The particular brackets herein disclosed for mounting the lever or rocker arm 58 allow this lever or rocker arm to be positioned above the stripper so that no unnecessary openings or discontinuities need be formed in the stripper. Furthermore, the preferred form of the bracket allows mounting on either the top or the side of the bracket as circumstances may require, and the bracket actually may be moved to and from the top and side from one job to another. Additionally, the combination of these brackets with the particular spring disclosed enables any given lever or rocker arm to be adjusted longitudinaly of itself for proper coaction with a job of a great number of possible sizes. The single spring advantageously serves the triple purpose of retaining the lever or rocker arm in adjusted longitudinal position, of biasing the stop finger on the arm into engagement with the work piece, and of biasing this finger against the direction of movement of the work piece.

The particular example shown and described herein will be understood as being by way of illustration. Various structural changes are possible and will be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.

I claim:

1. A die stop mechanism for punch presses and the like comprising a bracket adapted to be mounted fixedly on a punch press, a second bracket, means pivotally mounting the second bracket on the fixed bracket, a stop lever, a stop portion on said lever engageable with a. formed part of a workpiece for stopping said workpiece in a predetermined position, said pivotally mounted bracket having a channel portion and confronting flanges on said channel portion for slidably receiving said stop lever, and a spring curled around the pivotal connection between the two brackets and having one end engaging the fixed bracket, the other end of said spring extending diagonally across said stop lever and outwardly away from the fixed bracket, and then diagonally back in the other direction and further outwardly away from the fixed bracket, and then substantially transversely across the stop lever and upwardly along one side thereof to bias said lever pivotally to urge the stop portion toward said workpiece and against the movement of said workpiece, and frictionally to hold said lever against longitudinal movement thereof in the pivotal bracket.

2. A die stop mechanism for punch presses and the like, comprising a bracekt adapted to be mounted fixedly on a punch press, a second bracket, means pivotally mounting the second bracket on the fixed bracket, a. stop lever, a stop portion on said lever engageable with a formed part of a workpiece for stopping said workpiece in a predetermined position, said stop lever being carried by said pivotally mounted bracket, and a spring having one end engaging the fixed bracket, the other end of said spring extending diagonally across said stop lever and outwardly away from the fixed bracket, and then diagonally back in the other direction and further outwardly away from the fixed bracket and then substantially transversely across the stop lever and upwardly along one side thereof to bias said lever pivotally to urge the stop portion toward said workpiece and against the movement of said workpiece, and frictionally to hold said lever against longitudinal movement thereof in the pivotally mounted bracket.

3. A die stop mechanism as set forth in claim 2 wherein the second bracket includes a sleeve portion slideably receiving said stop lever.

4. A die stop mechanism for punch presses and the like, comprising a bracket adapted to be mounted fixedly on a punch press, a second bracket, 2. means pivotally mounting the second bracket on the fixed bracket, a stop lever, a stop portion on said lever engageable with a formed part of a workpiece for stopping said workpiece in a predetermined position, said stop lever being carried by said pivotally mounted bracket, and a spring having one end engaging the fixed bracket and having an arm extending outwardly away from said fixed bracket along said stop lever in close proximity to said stop lever and having one portion engageable with said lever substantially in the plane of said pivotal mounting means to urge the stop portion against the movement of said workpiece and having an adjacent portion engageable with said stop lever substantially perpendicular to said pivotal mounting means and containing the stop lever whereby pivotally to urge the stop portion toward said workpiece, said spring frictionally holding said lever against longitudinal movement thereof in the pivotally mounted bracket.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,010 Melin Oct. 27, 1936 2,078,706 Boker Apr. 27, 1937 2,314,690 Dawson Mar. 23, 1943 2,377,824 Strobl June 5, 1945 2,454,143 England Nov. 16, 1948 2,459,101 Uhrmacher Jan. 11, 1949 2,610,686 Krasberg Sept. 16, 1952 2,633,915 Dahlstrom et a1. Apr. 7, 1953

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