US2381237A - Means for safeguarding operators on power presses - Google Patents

Description

Aug 7, 1945.- A. w J.- WELLS 2,381,237

MEANS FORSAFEGUARDING OPERATORS ON POWER PRES SES Filed Feb. 10, 1944 4 Sheets-Sheet l MUM 9W 2 3 2 t e 1 m 8 S 3 2 6 6 h H4 R E w. o P w ss L R L Em W P. J wm d .W AA U GP. E F .A .S .R O F s .M 5 4 9 1 7 Aug.

Aug. 7, '1945; A. w. J. WELLS Y 2,381,237 I MEANS FOR SAFEGUARDING OPERATORS ON POWER PRESSES Filed Feb. 10, 1944 4 Sheets-Sheet s elm- Aug. 7, 1945.

A. w. .1. WELLS MEANS FOR SAFEGUARDING OPERATORS on POWER PRESSES Filed Feb. 10, 1944 4 Sheets-Sheet 4 A I 0 V 3 v 7 7 8 M 2 9 4 6 3 3 I F 1 WM 4 2 I. i 4 1 .l.. m 2 2 3 ,m 3 I 2 n I 3 0 m1 2 @E n hlMg ll 3 0 6 3 Q m H i f V which is removable to permit ofjrepeated tionz'of the press for blanking.

Patented Aug. 7, 1945 2,381,237 Fort SAFEGUARDING ornna'rons MEANS ON POWER PBESSES runes William John Wells, London, England Application February 10, 1944, Serial No. 521,895

In Great Britain March 1, 1943 9 Claims. (01. 192-134) This invention relates to means for safeguarding operators on power presses, which expression is to be understood as including stamping and like'machines in addition to presses.

In British Patent No. 528,343 I have described safety mechanism such that the shaft of the press cannot beset in motion to cause the ram to descend until after'a guard has been moved into a closed position in which it renders it impossible for the operator tomove her hand into position beneath the. descending ram. In this arrangement a release member on the ram was arranged to release the guard and allow it to return to its open position at orshortly after the completion of the down stroke of the ram. The present invention aimsat improving this safety mechanism in various respects.

, Firstly a press fitted with such a safety mechanism is not suitable for blanking. The present invention, however, provides a safety mechathe guard is closed, and the latter cannot open again until risk of injury to the operator is past. When however the guard is in the inoperative position and connected to the locking device, the

latter is held retracted, so permitting continuous operation of the press for blanking. To return the guard to the operative position this connection must be broken, whereupon the locking de-'v vice is returned by a spring or the equivalent to the safe position, from which, after establishment of the alternative connection with the/ guard, it can only be movedagain by closing tn guard.

In the case of the mechanism described in British Patent No. 528,343, the guard is returned to the open position at or shortly after the ram reaches the end of its downstroke; Experience, has shown however that it is possible for the operator in some cases to trap 'her fingers bean tween a projection on the upwardly movingram and the guard if she moves her hand in too rapnism which is eflective, like that above-described,

to safeguard the operator against injury when the press is used for forming operations, but which can be thrown out of action to permit of rapid repeated operation of the press for idly after the guard opens. The present invention provides mechanism which ensures that the guard will not open until the ram has completed as or nearly completed its up stroke.

blanking, which does not involve risk of injury to the operator's fingers.

The invention accordingly provides a power The press is conveniently set in motion by retraction of a release member which cooperates with the locking device so that. for forming. op-

press adapted for alternative use for forming and for blanking operations. and comprising a guard movable at will from a forming to a blanking position, a locking device controlled thereby, and

means'i'or efiecting alternative connections bestween the guard and the locking device such that when the guard is in the forming position the of the press except when the guard is closed and locking deviceis eflective to prevent operation to maintain theguard closed, duringoperation of the press. until the ram of the.press has'nearly completed its return stroke, while when the guard isin-tlieblanking position the locking device is ineiiective to prevent operation of the press.

Preferably the press includes a non-repeat mechanism, which normally limits the operation in: the press to a single stroke at each actuation of a treadle or equivalent actuating member,-the 1 non-repeat mechanism having a detachable part The guard thus has an inoperative position,

in which it is placed for blanking and an operativeposition in which it is placed ior forming.

when in the operative position it eflectively V safeguards the operator against injury since the shaft of the press cannot be set in motion unless operaerations, the release member can only be retracted' when the guard is closed, and prevents the guard from opening-again until ithas returned from its retracted position. To ensure that the guard cannot open until the ram has-nearly'completed it's stroke, the shaft of the machine may.

carry a cam which cooperates with the release member to prevent its return until shortly before the end of the up stroke of the rain One form'oi power press fitted with safety devices according to the invention will now be described in further detail by way of example, with reference to the accompanying drawings, in

- Fig. 1 is a front elevation of the press, Fig.- 2 is'a side elevation, I

Fig. 3-is a vertical section through the centre Y of the press, I 1 Fig. 4 is a rear elevation, with the flywheel removed,'

Fig. 5 is an enlarged scrap view of the connection between the guard and an actuating rod for retracting the locking device; and

Fig. 6 is an enlarged sectional view through the operating roller of anon-repeat mechanism.

Theguard, which is fitted to the front of the press, comprises two side members It joined by a the guard, engages over one end free the release slide the studs 12. The guard can be swung about the studs I3 from a down operative position (shown in full lines in Fig. 2) in which it rests in front of thework to an up inoperative position (shown in chain-dotted, lines in Fig. 2) in which it is out of the way for blanking.

To each side member I is fixed a forked member H which, in the operative .position of of a cylindrical cross bar l5 fitted to the machine frame. The outer faces of the forked members H are serrated (see Fig. 1) and nuts I9 screwed on to the ends of the bar l5 can-be screwed down to engage serrated washers l'l threaded on the ends of the bar with the serrations in the forked members M to lock the guard in position. This provides an adjustment for varying the spacing of the guard from the press as may be required to suit press tools of different dimensions. Linch pins |9 at the ends of the bar prevent the nuts l9 from being removed or lost.

The guard is formed of two sections, a. lower section l9 which can slide up and down in the side members, and an uppersection 29 which is fixed to, the cross member The lower section I9 has top and bottom cross members 2|, 22 which slide in slots 23 in the side members In, and is connected to the upper section 23 by links 23, pivotedat their lower ends to the member 2| and at their upper ends to links 25 fixed to the cross member The lower section normally tends by gravity to assume a lower position (shown in slide has returned to its original position, in which the hole 39 in it is in register with the lockin bolt 29. Only when this condition is fulfilled can the spring 29 move the latter rearwardly into locking position, thereby opening the guard through the agency of the actuating rod 32. This locking mechanism is similar in principle to that described in British Patent No."

528,343 but has theadvantage over the latter that it is enclosed in the body of the press, instead of being mounted on the side of the press. It is therefore impossible to tamper with it Or put it out of alignment.

The connection'between the actuating rod 32 and the arm 39 is a readily detachable one. The

forward end 39 of the rod is forked (Fig. 5) to receive theend of the arm 39, and these parts are secured together by a transverse pin 3| pass-' ing through registering holes in the arm and in the limbs of the forked end of the rod. These holes are of keyhole form, the slots registering and serving toaccommodate a projection 42 on the end of the pin 3|. After insertion of the pin chain-dotted lines in Fig. 3) in which it permits v of access by the operator to the lower die 26 of the press. In this open position of the guard, the 'upper section 29 is swung inwardly by the links 25 into the chain-dotted position in. Fig. 3. To close the guard the operator grasps the lower edge of the upper section, drawin it into the plane of the lower section,- hich is thereby pulled upwards to meet the upper section. In this position (shown the press. V

In a cavity 21 in the body of the press is located "a locking bolt 28 which extends at right angles to the plane of the guard and is normally pressed rearwardly by a spring 29 in a release slide 3|, andyso prevent the latter from being moved to set the press in operation. Beneath and ofiset from the locking bolt 29 is a rod 32 for actuating it. This actuating rod is cranked inwardly at |32 (Fig; 4) near its rear end and terminates in a rearwardly extending fork 232 en agin a link 33 which is pivoted at its upper end to a rod 33 iouggialled in the machine frame.. On the rod 33 is fixed a bell crank lever 35, one arm 38 of which has a slot 31 engaging a pin 39 on the locking bolt29. The rod 32 is pivoted at its front end to an arm 39 fixed to the cross bar when the guardis open, the locking bolt 28 is in the locking position. On swinging the upper section into position to close the guard, however, the actuating rod 32 is pulled forward to withdraw the locking bolt 23 and 3| as shown in Fig. 3. The

latter is then able to move down, as later described, when the operator presses a treadle (not to engage a hole 30 infull lines in Fig. 3) it is" impossible for the operator to put her hand into slide 3| referred to above.

to Join the parts together, thepin is turned to bring the projection 42, which now rests against the outer surface of one limb of the rod, out of register with the slots (see Fig. 5). To uncouple the parts it is turned back until the projection is opposite the slots, when it can be drawn forward to free the arm from the rod.

In the raised inoperative position of the guard, to which it can only be moved after uncoupling the arm 39 from the rod 32, slotted extensions 33 of the side members thereof engage over studs 93 fitted to the machine framework. Nuts 45 on these studs, which are held against removal by linch pins 39, are then screwed down to retain the guard in the raised position. In this position it is necessary that the locking bolt 29 should 40 be withdrawn. To this end a prolongation ll ofthe left hand extension 33 is coupled to a hump 48 on the actuating rod by passing the pin 3| through holes 59, 5| in these two parts. and the rod is thus held in position (see chaindotted lines in Fig. 2) to maintain the locking bolt withdrawn. The guard cannot of course be returned to the down position without removing the pin and so allowing the locking bolt to return to the locking position.

At the rear of the press (Fig. 4) is the release springs 32 to an up position in which it is locked by the locking bolt as already described. When in the up position the upper end '53 of the release slide engages a pivoted dog 34. mounted to turn with the shaft 53, and retain it in a position in which the shaft is not coupled to the rotating flywheel 56 (Fig. 1). On downward retraction of the release slide 3| to free the dog 33, a spring 31 causes the dog to turn thereby clutching the shaft to the flywheel 96 by 58. as described in my copending 521,894, and causing the ram I9 (Fig. 3) to descend. 'After the shaft has almost completed a revolution, the dog 59 is intercepted by the release slide -3|, yvhich at this stage has returned to the up position as described below, thereby declutching the shaft and preventing the ram from descending a second time. The shaft carries a cam 39 arranged to actuate a brake 69 towards means of a key the end of the, upward stroke of the ram.

This is urged by application No.

acetate its other end'toa release-bar 64. When -therefore thetreadle is depressed this release'bar is caused'to descend. 'The release bar is formed with aprojecting' latch 65 anda spring 66'nor- 'mally holds the release bar in'aposition in which the latch 65 engages a nose 6'! on therelease smear. Downward movement of therelease bar- 64 will therefore, provided the locking bolt has been'withdrawn-by closing 'theguard, draw the release slide 3| down to'free the dog and engage the clutch. On the shaft of the press I is mounted a cam 68, cooperating with 'a' roller 69 at the upper end of the release 'slidewTh'is cam is so shaped that, notwithstanding-release of the pressure of-the*='opei ator s foot on are treadle, the springs 52- associated with the-release slide cannot lift the latter back into its upposi- What claim as myinventi-oir and desire to secure by -Eetters'Patent: is:

' I. a powerpressghaving'a reciprocatable the combination-with release. means for: setting the press in operation and an actuating member therefor, of a safety guard support movable at will in relation to the press b'etween: an inoperati've p'ositioni'nit-i's' placed to. enable the effective operation of said release means, and

tionuntil some time during the last quarter of the up stroke of theram. As explained above, the hole in the release bar is only-brought into register with-the locking bolt to permit of rearward movement of the sameto'open the guard, when the release slide has returned to theup position.

To prevent a repeat stroke of the ram, in case the operator should maintain the pedaldepressed, a roller 80 is provided on. a member 10 fixed to the shaft. This roller strikes the'release bar 64 during the up stroke of the ram, causing.

the release bar to pivot 'about its lower, end

against the action of..its spring 66 sufliciently to free the latch 65 from the. nose: 61' of the-release slide.

The latterwill therefore be lifted to its up position by its springs 52 and lockedv by the locking bolt, the associated" cam 68; permitting: of such upward-movement .at this stage. When theroller 80 has passed the release bar,

the. latter springs backintoposition to bringthe' latch below the nose on the release slide. release of the pedal, however, the release bar will rise,.the latch wiping over the: nose on the release slide and. engaging, .above. it. .to 1 reset the parts in. their. original position; 4;. g

When. the pressis tobe used forblanking the non-repeat roller 80. is removed, This roller ,(see

means'afer'establishing two alternative connections betwee'n'said guard and said lockingdevice,

- one connection; which can be established only whentheguard support is in the inoperative PQ'SLBIOII; serving torender the locking device inoperative. and the other connection which can be established onlywhen the gu'ard'support is in Fig'.,6)*has a threaded shankll fittingiintoare- .cess 'imthe supporting memberv 10. This recess contains asplit cone 121 held in po ition so that it? cannot fall out when the roller .is removed and locked against rotation by; a key 13. A threaded I recess 14 isprovided in one of the brake members and the shank of the roller can bescrewed into this recess,, toensure that. the roller will not go 'astramwhenit is required to put the non-repeat mechanism out of action. a

A. further safety device isprovided for-ensuring that the guard cannot open, despite ,the return of the release slide to the up position until' the shaft has, actually,stopped' rotating. This consists of a link 15 (Fig. 3) pivoted to the arm 16 of the bell crank 35, said link carrying a pin 11 which, when the locking bolt 28 is in the looking position, engages in a hole 18 in the shaft 55. When the guard is closed, this 'pin 11 is withdrawn from the hole I8 as an incident to the retraction of the locking bolt from the hole in the release slide. The locking 'boltcannot,

shaft has completed a revolution and stopped, thus permitting the pin 11 to re-enter thehole 18. i i

The press includes a shear pin and stop mechanism for safeguarding against flywheel seizure as described in my copending application No.

however, return to the locking position until the theop'erative" position; serving to renderth'e lock mg device operative except when theguard is in the closed position and to m'aintain the guard in the closed position so long-as the moving ram can: endanger the operator;

' 1213111? 8w D r"l g a reciprocatable vampthecombination withrelease means i for. setting them-press in operation and an actuating member therefor; ot'a safety guard support mov able atwiill in relation t'o the press between an imperative position i :v whi h: 11; is placed my able the press'to be used for blanking purposes and an operative position, in which it is placed to enable the press to be used fo'r' forming purposesa safety guard whiclris movable in relation to; said support between an open position and-a closed position in which it prevents injury totlie operator bythe ram, a locking device for preventing" effective operation of said release means, means for establishing two alternative connections between said guard and said locking device,- one connection, whiclr'can be established only" when the guard support'is in the inoperative position, serving to render the locking, device inoperative and the other connection, which can be establisl'ied only when the guard support is: in the operative position, serving to render the looking 'devi ceoperative except when the guard is in theclosedpositi on and to maintain the guard in the closed position so long as the moving ram can endanger the operator, anda non-repeat mechanism for normallyli'miting the operation of the press" to a single stroke ofth'eramon each actuation' of the release" means, said non-repeat mechanism including adetachable part, which is removable to disablfe said mechanism when the press is to be used for blanking.

3. In a power press, having an intermittently rotating drive shaft, and a reciprocatable ram operated by said shaft, the combination with a release member for setting said shaft in rotation, of an actuating member for operating said release member, a guard frame fitted to thepress, and movable in relation thereto between operative and inoperative positions, a safety guard which is movable in relation to said frame between open and closed positions, a locking device connectable by alternative connections to the guard in the operative and inoperative positions of its support, and a device for biasing the locking device to a locking position in which it prevents eifective operation of said actuating member, the connection between the locking device and the guard in the inoperative position of the guard frame serving to hold the locking device permanently retracted from its locking position and the connection between the locking device and the guard in the operative position of the guard frame serving to retract the locking device from its looking osition when, and only when, the guard is closed and to reopen the guard when it is safe to do so.

4. In a power press, having a press body, an intermittently rotating drive shaft, a reciprocatable ram operated by said shaft, and a constantly rotating drive member, the combination with a release slide, of an actuating member for operating said release slide to couple said drive shaft to said drive member, a locking bolt housed in a recess in'the body of the press and biased to normally engage the release slide to prevent operation thereof, a retracting member for withdrawing said locking bolt from engagement with said release slide, a guard ,frame fitted to the press and movable in relation thereto between operative and inoperative positions, a safety guard, which is movable in relation to said frame between open and closed positions, and means for effecting alternative connections between said guard and said retracting member, one connection, which can be made only when the guard frame is in the inoperative position, serving to hold the locking bolt permanently retracted, and the other connection, which can be made, only whentheguard frame is in its operative position, serving to retract the locking bolt when, and only when, the guard is closed and to reopen the guard when it is safe to do so.

5. Apparatus as claimed in claim 4, which comprises a pin linked .to the locking bolt and arranged to engage in a hole in the shaft when the bolt is in the locking position, the hole being in register with the pin only at the start and finish of the cycle of operation.

6. In a power press comprising an intermittently rotating drive shaft, a reciprocatable ram operated thereby, a constantly rotating drive member, and a clutch dog for coupling said drive shaft to rotate with said drive member, the combination with a release member, of a biasing device for holding said release member in engagement with said dog to hold the latter inoperative, an actuating member and a linkage connecting the same to the release member, said actuating member being operable to withdraw the release member to free the clog and thereby set the shaft in rotation, a locking bolt cooperating with the release member and biased towards a locking position to which it cannot move when the release member is withdrawn and in which it looks said release member against withdrawal, a movable safety guard operatively connected to the locking bolt and operating to withdraw it from the locking position when said guard is closed, a non-repeat vmechanism constituted by a linkage member,

forming part of the linkage aforesaid, and a member carried by the drive shaft and arranged, if necessary, to displace said linkage member shortly before the end of the machine cycle, to free the release member and permit of its return to disengage the clutch before completion of said cycle.

7. Apparatus as claimed in claim 6, in which the guard is detachable from the locking bolt and movable into an inoperative position to permitof blanking operations, the guard, when in the inoperative position, being capable of reconnection to the locking bolt to hold the latter permanently retracted and the member on the shaft being detachable so as to render the nonrepeat mechanism ineffective during blanking.

8. Apparatus as claimed in claim 6, in which said linkage member carries a latch normally engaging a nose on the release member, so that movement of the linkage member on operation of the actuating member is effective to Withdraw the release member against the action of its biasing device, the member on the shaft causing the linkage member to pivot and free the nose on the release member from the latch, thereby enabling the biasing device to return the release member into position to stop the press.

9. In a power press comprising an intermittently rotating drive shaft, a reciprocatable ram operated thereby, a constantly rotating drive member, and a clutch dog for coupling said drive shaft to rotate with said drive member, the combination with a release member, of a biasing device for holding said release member in engagement with said dog to hold the latter inoperative, an actuating member for withdrawing the release member to free the dog and thereby set the shaft in rotation, a locking bolt cooperating with the release member and biased towards a locking position to which it cannot move when the release member is withdrawn and in which it locks said release member against withdrawal, a guard operatively connected to the locking bolt and operating to withdraw it from the locking position when said guard is closed, and a cam on theshaft cooperating with the release member to prevent the latter from returning from the withdrawn position, and thereby permitting the locking bolt to open the guard by returning to the locking position, until shortly before the ram reaches the end of its return stroke.

ALFRED WILLIAM JOHN WELLS.

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