US1505467A - Guard for presses, stamps, and like machines - Google Patents

Description

Aug. 19, 1924. 1,505,467

H. D. JACKSON GUARD FOR PRESSES STAMPS, AND LIKE MACHINES Filed March 21. 1923 2 Sheets-Sheet 1 H. D. JACKSON GUARD FOR PRESSES. STAMPS, AND LI'KE MACHINES Filed March 21 192B 2 Sheets-Sheet z ill Patented Aug, 19, 1924 r/[Ttr orn ce.

HERBERT DAVID Jackson, 0F WAIiSALL, ENGLAND.

GUARD FOR PRESSES, STAMPS, AND LIKE MACHINES.

Application filed March 21, 1923. Serial No."626,588.

This invention relates to improvements in guards for power presses, stamps, and like tools, and refers particularly to an improved guard which is adapted to obviate any possibility of injury to the operator during 'a working stroke of the press or the like.

In the usual type of press or stamp a pulley is continuously driven by belting or like means and is temporarily clutched to the cross shaft which carries the pressoperating eccentric or like means by a key or other clutch which 'is thrown into engagement when a lever is depressed by the operator.

A fixed guard is generally provided on the left of the tools or dies so that the operator must place the blank upon thefixed die with the right hand which is also used for depressing the lever, and in theory safety is thus obtained since the lever cannot be depressed while the operatorsfingers are between the dies.

It has also been proposed to provide a sliding guard which is moved into position in front of the dies when the lever is depressed, but both of these methods fail to guard against the possibility of defects developing in the clutch mechanism, or of the press being given two working strokes for one depression of the lever either through the clutch key'becoming worn, or

through backlash developing in the-lever mechanism, and as the guard in the latter case only protects the dies when the lever is depressed injury to the operator may easily occur.

Guards have also been proposed which are brought into operation by the moving die as it descends on its working stroke, but such guards do not come into the full operative position until the die has moved a considerable distance, and also, owing to the rapid motion of the die, the movement of the guard itself is rapid and may cause injury to the fingers of the operator.

The object of 'my invention is to provide an improved guard for power presses, stamps and like machines, in which the guard is independent of the clutch or operating lever, and is positively brought into action by the rotation of the cross shaftso that the moving die cannot descend without being protected by the guard, and the'possibility of accidental injury to the operator is, eliminated.

A further object of my invention is to provide a guard which is brought into its active position before the moving diefhas travelled an appreciable distance on its working stroke and which protects thedies until the moving die is near the end OfltS return stroke. 1 1

This is particularly important for drawing dies where the moving die entersa con siderable distance into the fixed die and the clearance between the dies inflthe inoperative position is not great. 5

With these objects in view my invention essentially comprises a guard for power presses, stamps, and like machines, in which a guard member adapted to protect the tools or dies during the working. stroke is carried by a reciprocating member which is slidably mounted on the bed ofthe press or the like and is moved into the operative position by a lever and cam mechanism from the cross or driving shaftof the press as the movable die begins its working stroke and is withdrawn by a spring as the diereaches the end of its return stroke, the striking face of the cam: being arranged at such an anglethat the guard is moved into the fully operative position before the die has moved an appreciable distance on the working v stroke. I I

My improved guardmay'be arranged in a variety of ways to adapt it foruseon different types of presses, butone preferred embodiment, which is suitable for a variety of presses, has been illustratedbywway of example in the accompanying drawings in which Figure 1 is a plan of the guard operating mechanism showing the guard in its retracted position in full lines and in the forward, or operative position in dotted lines.

Figure 2, is a front elevation.

Figure 8, is a diagrammatic end elevation of the complete guard showing the lever and cam mechanism.

Figure 4, is a diagrammatic front elevation showing, in full and dotted lines respectively, the guard in the retracted and operative positions relative to the dies.

In the. drawings a is the guard member which. may conveniently be formedof sheet metal of a suitable size and shape corresponding to the dies with which it is used, and having its forward end curved round as shown at a in Fig. 1 to prevent injury to the operators hand if the guard should come into contact with it.

The guard is secured by bolts 6 to a rectangular reciprocating member 0 which is slidably mounted between and guided by three pairs of vertical rollers d upon a base plate 0 secured to the bed of the press by boltse.

The'member 0 is horizontally slotted for a portion of its length as shown; at c" and within this slot is housed a flat slide cam or wedge member f of substantially triangular outline as shown in Fig. 1. The rear edge of the member f is at right angles to the reciprocating member 0 and bears against one pair of therollers cl, while the front edge is inclined at an angle of, say, 45 and, bears against a roller g'carried on a vertical pivot at the forward end of the slot 0. A tension spring h is connected between a pin j on the reciprocatingmember c and a pin 70 on the bridge piece for the outer pair of rollers (Z or any other convenient fixed point and serves to retain the member 0 normally in the retracted position shown in full lines in Fig. 1.

The member f has an integral boss 7' into which is screwed one end of a horizontal rod Z atthe other end of which is a forked head m within which is pivoted the lower end of a substantially vertical lever 91. This lever is pivoted at 19 upon the frame of the press and carries at its upper end roller q engagmg a cam 1' on the cross or driving shaft As of the press. The cam. is preferably of an outline substantially similar to that illustrated in Fig. 3, and is keyed upon the shaft .9 in such a position relative to the crank or eccentric by which the moving die of the press or eccentric is reciprocated that the ca m lifts the roller g and'moves the upper end of the lever n outwards 'as the crank or eccentric moves over top dead centre on the working stroke, and as the movement of at the upper limit of its movement on the return stroke the dies are covered by the guard.

The action of the device will be readily followed from the drawings.

As the moving die approaches the upper limit of its movement on-the return stroke the roller 9 rides ofi the cam 7' and the wedge member f together with the rod Z and the lower end of the lever 12 is free to moveto the right in Fig. 3 under the influence of the spring h which retracts the member 0 and with it the guard a into the position shown in full lines in Fig. 4. The dies t are thus uncovered and blank can be placed in position on the fixed die. When the press clutch is engaged and the shaft 8 commences to rotate, the cam engages the roller 9 and rocks the lever a about its pivot so that the lower end of the lever is carried to the left in Fig. 3 taking with it the rod Z and the wedge member f which in turn moves the reciprocating member 0 forward to bring the guard into the operative position as shown in dotted lines in Fig. a. All danger of the operators fingers being trapped be tween the dies is therefore eliminated. Small bolts and washers a may be provided on the edge of the wedge member f parallel to the reciprocating member 0 to, formastop for the member f and prevent it from being completely withdrawn from the slot in the member 0 by a too violent actuation of the lever a, but these are not essential in all cases.

I claim: 1. A guard for power-presses, stamps, and-like machines, comprising a guidedreciprocating member, a guard member carried by the said reciprocating member, resilient means for retaining the reciprocating member normally in the inoperative posimember, a guard member carried by the-said reciprocating member, a base plate, pairs of fixed rollers .on the saidwbase plate between which rollers the sa1d reciprocating member is slidably guided, a wedge member of substantially triangular outline adapted to slide in a slot in the reciprocating member and abutting between one pair of fixed rollers and a roller at one'end of the slot, a-lever pivoted upon the frame of themachine, a

horizontal rod connecting the lowerend of the said lever to the said wedge member, a

machine, and a spring which effects the return movement of the reciprocating member. In testimony whereof I aifix my signature.

HERBERT DAVID JACKSON.

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