US2679307A - Protective system for punch presses or other machines - Google Patents

Description

May 25, 1954 KQCH 2,679,307

PROTECTIVE SYSTEM FOR PUNCH PRESSES OR OTHER MACHINES Filed Aug. 22, 1951 2 Sheets-Sheet 1 INVENTOR. fir'ai/a/r 0c// Arm/ms? May 25, 1954 K 2,679,307

PROTECTIVE SYSTEM FOR PUNCH PRESSES OR OTHER MACHINES Filed Aug. 22, 1951 2 Sheets-Sheet 2 INVENTOR. FQEOfR/CK /\.o 09

ATTORNEX Patented May 25, 1954 ATE-NT OFFICE B T cTIVE-sYs-IEM FoR-PuNo Pnnss s oa'lornnn MACHINES Ereclcricl; Koch, Sparta Rutherford, v

Application August 22, 1951;"Serial-No.- 243,149

1 plaim. l

-Ihe invention herein disclosed relates. to the protection of punch presses and. other machines against inaccuracies or failure in the feedingof stock thereto.

Particularly .the. invention is concerned with presses equipped with means such as a slide. feed for automatically. supplying the machine with stock.

Theigeneral purposeof the-invention is. to pro- -Such. reasons. might be the buckling of the stock, between theieed unit. and the die, punch .orother; toolportion of the vpress, failure, to impart a full feedcstroketo the stock, reaching the end. of therstoclconthestock,being too thick or too thin or. too Wide. or too, narrow.

. These and. other failures .or inaccuracies are guarded against inthe-present invention byrthe provision of appropriately placed detector switches allconnected-in such relation that the actionef any. one of themwill, serve to trip or stop=the press orothermachine.

1 Particularly it is. .an .iobject ;of the -invention .to provide such a protective system in a simple,

practical form readily applicable to.. rna chines in use.

Other desirable'objects attained by the invention are set forth, orwill, appear in the course I :of thefollowing specification.

The drawings accompanying and forming part of the specification are illustrative of i present commercial embodiments of the-intention but structureand arrangement may he modified and changed as-regards silch illustration, all within the true intent and scope of theinvention as here nafter defined and claimed.

. Fig. 1 in the drawings is a side elevation of a power press having theinVentiOn applied thereto and showing the pressin normal running condition with the starting pedal held down byfthe automatic trip-mechanism;

2 is an interior view of the controlbox removed. from the press andshowingthe parts as they appearin Fig. 1;

Fig. 3.is an end view of the control unit; Fig.- 4 is a horizontal sectional view on substantially the plane of--line 4 5 of Fig. 2;

Fig. 5 is a broken front elevation of the press showing two of the detector switches the main control switch mounted thereon;

Fi 6 is Wirin diagra ,Eig. 7 isan-internal view of a -modifiedv-form .0? o r l; x;

Figs. 8, 9 and are hrokendetail-views/illus- .trating. operation of .this. second form of the in- 1 .vention;.. Fig. 8 :showing. position .of .parts. ,-wi th the machine locked in running .position;;..Fig.; 9

., showing .themachine tripped, with thesolenoid .deenergized. and. ethe. trip rod .moving upward; andFig. .10, showing. 1 the stopped position. with the trip rod upand lockedin thatrelation by reenergization; of the; solenoid;

. Fig. 11,.is a wiringidiagram .showing; par.ts ,,as in the locked, Fig.,10, position.

In Fig. l a power press isshownhaving.aioot pedal 'l,,,for;star ting and .controllingihesame.

- This may be considered agonesrevolutionpress ththcpu lrod 8 extendin -f m thepeda ,connected with arock lever. 9 having atripcon- ,ne t on mi 8 ext ndin n ith one-revo utio clutch of the press.

Fu ther, it may-.be con i erc l.th th res 5. qu pp dwi a s i f e part xs owna I l n F 5. operatedir m thepre sand a ran to advanc st i tock. .s cprs e t th ompanion. die memb n; ca r e b -.--.t.

; .lca ineit e pe l asap i .r I 5 and bolst 16! he, i ention. inclu s, m chan 1 lat i ea ld n the edal. dow science s oc is being properly fed, and-{fol automatically ree press if stock is not Pr per y. advancednr... sam [o h r d fe .1.9

.l ihelie l-xiown leic h wn. s when. cran ever. .l'i piyot ed at ISZin abox or case fl9 adapted to be ho ted atj Zilpvr the side of the .i r sen sc trr s aihei ri hit o the same. a projecting: lug 2 Z to engage over a stop block 3 ,e tab y-. 9 @n;.-.-ihe.; u re 8 set screws.

A- spring 25 acting on the horizontal arm 26 tends .to retract the hookjor nose end of thebell crank and a magnet 27 having. its armature- 28 connected with this arm. acts to rock the detent outward into holding engagement with the ,trip lOCl. A i

in series with thellatchingand trippingv magnet,

By arranging feeler switches Iontesting-different conditionsand by connecting theseilall the znachinefmayibernadeto stop'when anyone or all of the conditionsguarded against occurs. 4 In the present illustration thereIisf arunout switchill. positioned to detect the end. of the stock, a switch 3B .for',detectingbucklingofthe j stock .between the ieed udevice and. dies and; a

switch ,3: positione'dj toladetect j short feeding Lof the stock.

These may be microswitches, therunout switch by the stock and the buckle switch normally closed and arranged to be pushed open by the upward buckling of the stock. Additionally, an on and ofi switch 32 may be located in convenient position on the front of the press for rendering the protective system operative or inoperative.

The various feeler switches may be connected in circuit when and if required, by flexible electric cords 33 equipped with attachment plugs 34, Fig. 1, adapted to be engaged in plug receptacles 35 on the front of the control box IS.

The wiring for these series connected receptacles while not shown in detail, is illustrated generally in the wiring diagram, Fig. 6, which shows the three feeler or detector switches in use as connected in series in the supply line 36 for the trip magnet 21.

Fig. 1 shows the supply line for the holding magnet as completed by an electric cord 3'! equipped with an attachment plug 38 for engagement with a plug receptacle in an ordinary wiring circuit.

In the case illustrated the control box is equipped with four plug outlets 35. Only three of these are shown as in use. The circuit at the fourth outlet may be temporarily closed by a jumper or connection of some sort, such as a fuse plug. Instead of using jumpers for the plug outlets not in service, these outlets may be of the normally closed or short circuited design which will open up to connect an extension cord in circuit when the plug of such cord is inserted in the receptacle. In such a construction the circuit at the plug receptacles will be normally closed but an extension cord circuit may be connected at any time by simply plugging it into one of the receptacle outlets.

The invention makes it possible to readily convert an ordinary punch press with a stock feeding unit into an automatic production machine which will continue in operation unattended so long as the right stock is properly fed to the same, and which will automatically stop, with the ram lifted, if stock is not present or is deiective or is improperly fed.

The control box is a simple but substantial unit which can be bolted to the side of the machine and in that relation provides a rugged and reliable means for holding the machine in operation and for tripping the machine and saving it from improper operation.

The microswitches may be mounted in position to detect various irregularities or faults in feeding, by the use of suitable mounting clamps, brackets or the like such as shown at El, Figs. 1 and 5, and they are connected in circuit by simply plugging them into open receptacles on the control box.

Figs. 1, 2 and 6 show the stop block 23 as having a bevel or incline at the'under side of the same, opposed to the hook portion 22 of the bell crank to act as a cam to force the bell crank back, against the pull of the magnet, so that with the magnet energized, after setting up the press, the foot pedal may be depressed to start the press.

The second form of the invention illustrated in Figs. '7 to 11, includes as an additional safety factor, means for locking the press in the stopped position and requiring purposeful, manual action on the part of the operator to again start the press.

Fig. 11 shows the holding latch in the form or" a sliding bolt 4| carried by a solenoid core 4 17.2 and arranged to be projected from the control box 43 by solenoid winding 44 and to be retracted by fiat spring 45.

The solenoid may be connected in the energizing circuit 35 in series with the several control units, as shown in Fig. 11, so that as in the first instance, it will be energized when all these switches are closed and will be deenergized when any one of them is opened.

Figs. 7 and 8 illustrate the normal running position of parts with the solenoid energized and the bolt 4| projected over the top of the stop block 23, holding the rod 8 down with the treadle of the press down in the running position.

Fig. 9 illustrates a tripped, temporary condition of the parts in which the solenoid has been deenergized, the bolt 4| withdrawn by the retracting spring 45, releasing the stop block and permitting the treadle rod 8 to move upward under impulse of the spring for yieldingly supporting the treadle in the upper, stopped position of the press.

Fig. 10 shows the rod 8 all the way up, in the fully tripped position and held in that relation by the slide bolt 4| projected in this case, beneath the holding shoulder of the stop block 23.

This projection of the bolt for securing the press in stopped condition is automatically efiected in the illustration by a switch 46 located in the control box, Fig. '7, which, as shown in the wiring diagram, Fig. 11, is connected in a jumper circuit 43 bridging the several control switches and arranged to be closed by a plunger 42; positioned to be actuated by a trip block 49 in the upward movement of rod 8.

This trip block 49 is secured in position on the rod so that it will only actuate the holding switch 46 after the block 23 on the rod has passed up above bolt 4|, and will then retain plunger 48 in position holding the switch closed.

Consequently in the form of invention shown in Fig. 7. the solenoid will be automatically energized to secure and hold the press stopped any time any one of the control switches has been actuated through any fault in the feeding of the press.

To again start the press the solenoid is deenergized, in the case illustrated, by a special release push-button 50 shown in wiring diagram, Fig. 11, connected to interrupt the jumper circuit 41.

This arrangement requires that the operator of the machine take positive action to unlock the control mechanism before he can start the press again. In this case the switch button 50 must be pushed and held While the foot pedal is being depressed to start the machine. If conditions then are in proper order the machine will start and continue to operate, but if any of the control switches are open the machine will again be stopped and be locked in the stopped relation.

In addition to control switches already mentioned, other controls may be provided such as the guard indicated at 5! in Fig. 11 and which is in the nature of a gate to swing down into position, closing access to the dies and which gate when swung down, closes a control switch 52 connected in series with the other control switches.

This safety gate form of control may be plugged into the control box by a cord connection such as that indicated at 33 in Fig. 1'.

' In setting up this safety guard form of control the gate may be equipped with a point or projection such as shown at 53 in Fig. 11, to extend through an opening in the stationary structure in order to operate the switch 52, to prevent accidental or unintentional closing of this switch.

Other forms of safety devices may be employed, the invention enabling these to be quickly plugged into service relation on the control box.

The circuits shown in Figs. 6 and 11 are representative, it being realized that these may be modified and changed in various ways. They may include various forms of protective or safety devices such as fuses and the like, and condensers or resistors may be connected, as indicated at 5 1, to prevent arcing and to otherwise take care of loads or surges occasioned by the control switches.

While normally closed circuits have been illustrated, it will be understood that the system may be designed for operation on a normally open circuit, with the control switches arranged in parallel, open circuit relation.

In the two examples illustrated in Figs. 2 and '7, the holding bolts are projected by magnets in the form of solenoids and retracted by springs.

This arrangement may be varied, for one instance, gravity be employed in place of spring force for retracting the holding bolt.

What is claimed is:

A unitary attachment for converting a power press, or like stock handling machine, having a control member which, when held depressed, will keep the machine in continuous operation and comprising a control box having means for mounting the same in fixed relation on the machine adjoining said control member, an abutment on said depressible control member, a latch in said control box projectible to engage over said abutment to hold the control member in the machine-running position and retractable to release said abutment to permit the control member to stop the machine, said latch in the projected position being yieldable under engagement by the abutment to permit the control member being depressed to start the machine when the latch is in the projected relation and whereby said latch will then hold the control member in the depressed position when the machine is started by depressing the control member, an electromagnet in said box arranged to effect release of the latch from holding engagement with the abutment on the control member, electric receptacle outlets on said control box, stock detecting switches, brackets for mounting said switches in different positions on the machine for detecting different stock feeding conditions, said stock detecting switches having cord connections terminating in attachment plugs insertable in the difierent receptacle outlets on the control box and electrical connections within the control boX for connecting any one or any number of said stock detecting switches plugged into one or more of said outlets in controlling relation with said electromagnet, and whereby said stock detecting switches may be set up on the machine to detect difierent faults in the feeding of stock, and the control member may thereupon be depressed to start the machine and the unit will keep the machine in operation so long as no stock feeding fault, which any one of said switches will detect, occurs and whereby when any such fault arises the electromagnet will effect release of the latch from holding engagement with the abutment to permit the released control member to stop the machine.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Country Date Germany May 9, 1941 Number Number

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