US2722274A

US2722274A - Means for insuring the correct positioning of strip stock in progressive punch press dies

Info

Publication number: US2722274A
Application number: US273904A
Authority: US
Inventors: David O Turnbull
Original assignee: Missouri Automatic Control Corp
Current assignee: Missouri Automatic Control Corp
Priority date: 1952-02-28
Filing date: 1952-02-28
Publication date: 1955-11-01
Anticipated expiration: 1972-11-01

Description

Nov. 1, 1955 Q TURNBULL 2,722,274

MEANS FOR INSURING THE CORRECT POSITIONING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS DIES Filed Feb. 28, 1952 3 Sheets-Sheet 1 5 48 ,g// I/ENTO R:

H16 HGENT N 1955 D. o. TURNBULL MEANS FOR INSURING THE CORRECT POSITIONING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS-DIES Filed Feb. 28, 1952 5 Sheets-Sheet 2 Willi/01110110011111,

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MEANS FOR INSURING THE CORRECT POSITIONING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS DIES Filed Feb. 28, 1952 3 Sheets-Sheet I5 im z-n'rae 04100 0- TMQ/YBl/LL United States Patent MEANS FOR INSURING THE CORRECT POSITION- ING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS DIES David 0. Turnbull, Jennings, Mo., assignor to Missouri Automatic Control Corporation, St. Louis, Mo., a corporation of Missouri Application February 28, 1952, Serial No. 273,904 3 Claims. (Cl. 164-59) This invention relates to means for insuring the correct positioning of strip stock in progressive punch press dies and for causing or permitting the punch press to be operated only when the stock is so positioned.

An object is the provision of a retractible locking means arranged to interlock with the strip stock when it has been advanced to the correct position, thereby to hold the stock in correct position, and to utilize the movement of the retractible means as it is entered into locking engagement with the stock to actuate a control device for controlling operation of the punch press.

A further object is the provision of means for causing the locking means to be moved between the locking and retracted positions in accordance with the position of the movable portion of the dies so that the locking means is retracted permitting the stock to be advanced as the dies are parting, so that the locking means is caused to engage the stock before the dies have completed their parting movement whereupon this lock engaging movement actuates a press control to a press tripping position before the press has reached top dead center, and so that the locking means is thereafter again retracted slightly before the dies again meet, thereby to permit any necessary minute adjustment of the stock by reason of stock guide pins carried by the dies.

A further object is to provide in combination with the above, means in a set of progressive punch press dies for blanking the stock, when in the initial position in the dies, so as to provide a notch or the like therein adapted to cooperate with the retractible locking means as the stock is advanced to the neXt position.

A further object is to provide in combination with the above, blanking means in a set of progressive dies for forming a transverse shoulder in the strip stock when in the first position and cooperating stop means on the stationary section of the die whereby stock feeding is stopped when advanced to the second position, thereby to permit entry to the retractible locking means.

A further object is to provide a device of the above character which is structurally included with a set of progressive punch press dies so as to form a unitary assembly adapted to interchangeable use on different punch presses.

These and other objects and advantages will become apparent upon reading the following description in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a view showing progressive operations upon a section of fiat strip stock as it is fed through a set of conventional five position progressive dies which are equipped with means for forming a notch and shoulders in the edge of the stock in the first position.

Fig. 2 is a top view of the retractible locking device shown attached to the bottom stationary section of the die set and shown in a locking position with the locking bar entered into a notch in the strip stock, only a fragmentary portion of the lower die section and strip stock being shown;

ice

Fig. 3 is a cross sectional view of the stripper guide attached to the lower stationary die section and is taken at 33 of Fig. 2;

Fig. 4 is also a cross sectional view through the same stripper guide taken at 4-4 of Fig. 2;

Fig. 5 is a cross sectional view through the retractible locking device and is taken on line 55 of Fig. 2;

Fig. 6 is also a cross sectional view through the retractible locking device and is taken on line 66 of Fig. 2;

Fig. 7 is a side elevation of the retractible locking device with parts thereof sectionalized and is taken on line 77 of Fig. 2;

Fig. 8 is a top view of the retractible locking device with the top cover of the housing removed and is taken on line 88 of Fig. 7;

Figs. 9 and 10 are schematic views of a preferred form of the invention and are similar except for being in different operative positions. In Fig. 9 the dies are shown fully open with the retractible locking device engaging the stock and the press control in tripping position, and in Fig. 10, the dies are shown partially open on the up stroke with the locking device retracted permitting the feeding of stock; and

Fig. 11 is a schematic view of the invention shown in connection with a conventional power driven punch press.

The punch press illustrated in Fig. 11 has a frame 101 in which is journalled an eccentric shaft 102. The shaft 102 has an eccentric 103 which vertically reciprocates a head 104. At one end shaft 102 carries a fly wheel 105 which freely rotates on the shaft and which is driven by suitable power means through a belt 106. A conventional self-releasing, self-cocking clutch device is indicated at 107 which, when tripped from a cocked position, engages the shaft and fly wheel for one revolution and then releases and automatically recocks in a manner well known and understood in the art. A clutch tripping device is indicated at 108 which takes the form of a pneumatic actuator having a cylinder in which is fitted a spring returned piston 109. The piston is connected to clutch operating arm 110, and when the piston moves downward under pneumatic pressure, the arm is rotated counterclockwise and trips the clutch. Compressed air for the operation of the actuator is supplied from a suitable source through an air line 111. Interposed in air line 111 is a normally closed, electromagnetically operated valve 57 which, when energized, opens to admit compressed air above piston 109. When valve 57 is closed, the piston return spring returns the piston 109 and arm 110 so as to permit recocking of the clutch device. Mounted on the bed 112 of frame 101 is the stationary die section 12 of a set of progressive dies, and the cooperating movable section 11 of the die set is carried by the reciprocating head 104.

In Figs. 9 and 10, the upper movable and lower stationary sections of the set of progressive punch press dies are shown fragmentarily at 11 and 12 respectively. A pair of

switches

13 and 14 are attached to and movable with the upper die section 11 and a pair of

switch operating cams

15 and 16 are attached to the stationary die section 12. The switches are provided with operating

arms

13a and 14a which follow the surface of the cams.

Switches

13 and 14 are both self-returning, but to opposite operating positions, switch 13 normally returning to a closed position while switch 14 is normally open. Also attached to the lower stationary section of the dies is an electromagnetically operated retractible locking device generally indicated at 17, having a reciprocating locking bar 18 guided in the stationary die section 12 and adapted to enter a notch 19 in the edge of the strip stock which is indicated fragmentarily at 20.

The device 17 is attached to the stationary die section 12 by means of

angle brackets

21 and 22 and screws 23,

24, and 25. The

brackets

21 and 22 are provided with horizontal and vertical attaching

screw slots

26 and 27 respectively to provide for horizontal and vertical adjustment. The reciprocating locking bar 18 is closely guided in a rectangular passageway 28 formed partly in the die portion 12 and partly in a stripper guide 29 which is attached to one edge of the die section 12 by means of screws 30, see Figs. 2 and 7. The stripper guide 29 has a groove 31 in its rightwardly extending portion, as shown in Fig. 4, in which the strip stock is guided across the lower stationary die section. The stripper guide 29 is also provided with a cut out portion 32, see Fig. 2, to clear punches (not shown) carried by the movable die section and which, in a first position blanking operation, removes that portion of strip stock outlined by the dotdash line in Fig. 2.

The removal of this portion of strip stock provides a notch 19 and a shoulder 33 in one edge of the stock. As the stock is fed leftward after the first station operation, the shoulder 33 is adapted to abut a shoulder 35, which is formed on the stripper guide by the cut-out 32. The feeding of stock is thereby positively stopped. It is preferable to also remove a portion on the opposite edge of the stock in the first position blanking operation so as to form a similar shoulder 33a, as shown in Fig. 1, and to also provide a stripper guide (not shown) on the opposite side having a cooperating shoulder similar to 35.

The retractible locking device includes a casing 36 to which the supporting brackets 22 are attached. Rigidly mounted within the casing 36 is an electromagnetic actuator 37 of the solenoid type, having a winding 38 and a reciprocating plunger 39 which is normally spring pressed in an outward direction by a spring 40. Pivotally connected to the outer end of plunger 39, by a clevis and pin arrangement, is an axially extending shaft 41. The shaft 41 is guided at its inner end in a perforated angle bracket 42 and at its outer end in a perforation 43 in an end wall of the casing 36. The bracket 42, which is attached to the bottom wall of the casing as by screws 44, see Fig. 6, also serves as a stop member to limit the outward travel of the plunger 39. The shaft 41 extends exteriorly of the casing 36 and has pivotally connected to its outer end, as by a clevis and pin arrangement, the flat locking bar 18. This clevis pin, which is indicated at 45, extends vertically to a point slightly above the top of casing 36, as indicated in Fig. 7, and passes through a slot 46 in a fiat horizontal bar 47 lying lengthwise across the top of the casing.

The bar 47 extends beyond the right end of casing 36 and has a bent down handle portion 48. The bar 47 provides a convenient manual means for retracting the looking bar 18 from the notch in the stock to permit setting up adjustments. The bar 47 is also provided with guides 49 and a spring 50 which is connected at one end to the handle portion 48 and at its other end to the casing and which normally biases the bar 47 leftward to a position in which a stop pin 51 therein bears against the rear guide 49. In this normal position, the slot 46 permits the free operation of the solenoid actuator to a retracted or locking position.

Also rigidly attached within the casing 36 and on opposite sides of the shaft 41, see Fig. 8, is a pair of

microswitches

52 and 53. The switches are of the self-returning type, normally in an open circuit position, and are provided with operating members 5211 and 53a which, when depressed, cause the switch contacts to be closed. The switches are so arranged that their operating members extend in opposite directions, whereby they are alternately engaged by

arms

55 and 56, carried by the shaft 41, as the solenoid actuator is operated to engaging and retracted positions.

The schematic views 9 and further include the normally closed electromagnetically operated control valve 57. The device 57 is series connected in a circuit with the switching device 52 by

leads

58, 59, and. The

leads 58 and 60 are connected to a plug 61 for convenient detachable connection to a suitable source of electrical energy.

The retractible locking device actuator winding 38 is series connected with the normally closed switch 13 and the normally open switch 14 in a first energizing circuit as follows: starting with a lead 62, through the contacts of switch 13 to a lead 63, through lead 63, through the contacts of switch 14 to a lead 64, through lead 64 and a lead 65 to winding 38, through winding 38 and through a lead 66. Leads 62 and 66 are connected to a plug 67 for convenient detachable connection with a source of energy. Winding 38 is also series connected with the normally closed switch 13 and the normally open holding switch 53 in a second energizing circuit as follows: starting with lead 62, through the contacts of switch 13, through lead 63, a lead 68, through the contacts of switch 53, a lead 69, lead 65, through winding 38, and lead 66 back to the plug 67.

In operation In Fig. 9, the dies are shown in their full open position with the normally closed switch 13 operated to an open position by the cam 15. The first energizing circuit for winding 38 is broken, therefore, at this point. The normally open switch 14 and the normally open holding switch 53 also being in open position, the second energizing circuit for the winding 38 is, therefore, also open and the locking device is, therefore, de-energized and permitted to move toward a locking position under the force of spring 40. Since the press operating control device 57 and switch 52 are series connected in an independent circuit, the device 57 will be energized only When switch 52 is closed, and switch 52 will be closed by the engagement of arm 55 only when the retractible locking device is de-energizcd and permitted full outward extension by the entry of locking bar 18 into notch 19 as shown. The cam 15 is arranged to open switch 13, thus de-energizing the locking device, during the last portion of the open movement of the dies and, consequently, just before the press crankshaft has reached top dead center.

The control valve 57, upon being energized, will cause the press tobe tripped and the movable die section 11 will start downward on an operating stroke. As the die section 11 moves downward, the normally closed switch 13 will be permitted to again close. The normally open switch 14 is still open, however, and the locking device is, therefore, still de-energized and in a locking position. The stock is, therefore, held against longitudinal shift ing by the locking bar 18 as the dies close. Just before the dies meet, however, the normally open switch 14 is closed by the lobe on cam 16 near its lower end. This action causes the actuator Winding 38 to be energized by the first circuit and the locking bar 18 to be retracted just before the dies come together. This provision precludes the possibility of any binding action between the locking bar 18 and "notch 19 which may interfere with the proper seating of the stock or which may prevent subsequent withdrawal of the bar 18.

During the following upward stroke of the upper die section 11, see Fig. 10, the normally open switch 14 is again permitted to open, but the actuator winding 18 is not de-energized by this action because the holding switch 53 is closed, thereby completing the second energizing circuit described above. The locking device is therefore held in a retracted position during the opening movement of the dies and until the cam 15 again engages switch 13 near the end of the opening stroke. The stock may be advanced, therefore, by any suitable means such as by conventional feed rollers indicated at 113 during the opening of the dies without interference from the locking 'bar 18.

As the advancing stock being fed to the succeeding position is positively stopped, as by abutting shoulders 33 thereon with shoulders 35 on the stripper guides, it strikes with some impact and there is usually some tendency to rebound, depending, of course, upon the flexibility of the stock and the conventional feeding speed. When the operation of the feeding device and cam operated switch 13 is properly coordinated, the locking means will enter the notch as the stock advance is stopped and rebound is, therefore, prevented. The stock is guided laterally in a conventional manner as by grooves 31 in parallel stripper guides.

It is to be understood that a rotary cam carried on the crankshaft of the press may be used instead of the

vertical reciprocating cams

15 and 16, in which case two of the switching devices could be eliminated. With the illustrated, preferred arrangement, however, the device is unitary with a set of punch press dies and is, therefore, conveniently interchangeable between presses.

The foregoing description is intended to be illustrative and not limiting, the scope of the invention being set forth in the appended claims.

I claim:

1. The combination with a set of punch press dies having a stationary and movable section, of an electromagnetically operated stock feed indexing device mounted on the stationary die section and having a spring pressed plunger arranged to enter lateral indexing notches provided in the edge of strip stock being fed through the dies when said device is de-energized and arranged to be retracted therefrom when it is energized, an energizing circuit for said device, a normally closed switch in said circuit arranged to be moved to an open position as said dies approach full open position and to again close as said dies start to close, a second normally open switch in said circuit arranged to be moved to a closed position as said dies approach a closed position and to again open as said dies begin to open, and a shunt circuit around said second switch including a normally open switch arranged to be actuated to a closed position by means movable with said plunger when said device is energized, whereby said plunger is retracted as said dies approach a closed position and is held retracted until said dies approach a fully open position and whereby it is released to a stock indexing position as the dies approach fully open position wherein it remains to hold the stock in position until the dies approach a closed position.

2. The combination with a set of a punch press dies having a stationary section and a movable section, of a spring pressed stock indexing plunger slidably mounted on said stationary section and arranged to enter lateral notches in the edge of strip stock being fed through the dies, of means including a cam surface carried by one of said die sections and a member on the other of said die sections cooperating with said cam surface for causing said plunger to be retracted as said movable die section approaches said stationary die section in a die closing movement, of means including a member carried by said plunger cooperating with a stationary member and rendered operative as said plunger is moved to a re tracted position to hold said plunger in a retracted position as said movable die section moves oppositely in a die opening direction, and of means including a second cam surface carried by one of said die sections and cooperating with a member carried by said other die section for rendering said plunger holding means inoperative as said movable die section approaches a full open die position.

3. The combination with a power driven punch press having a frame, a power driven fly wheel, an eccentric shaft, a reciprocating head driven through a die closing and a die opening stroke by said eccentric shaft, a selfreleasing, self-cocking, single revolution clutch device for intermittently connecting said fly wheel and shaft for one revolution when tripped, and clutch tripping means which when actuated trips said clutch, of a set of punch press dies having a stationary portion carried by said frame, and a movable section carried by said reciprocating head, of a spring pressed, stock indexing plunger slidably carried on said stationary die section and arranged to suecessively enter longitudinally spaced lateral notches formed in the edge of strip stock being fed through the dies, of means including a cam surface carried by one of said die sections and a member on the other of said die sections cooperating with said cam surface for causing said plunger to be retracted as said movable die section approaches said stationary die in a die closing stroke, of means including a member carried by said plunger cooperating with a stationary member and rendered operative as said plunger is moved to a retracted position to hold said plunger in a retracted position as said movable die section moves oppositely in a die opening stroke, of means including a second cam surface carried by one of said die sections and cooperating with a member carried by said other die section for rendering said plunger holding means inoperative as said movable die section approaches a full die open position, and of means including a member carried by said indexing plunger for actuating said clutch tripping means when said plunger moves into an indexing position in a notch in the stock.

References Cited in the file of this patent UNITED STATES PATENTS