US1929687A - Machine guard - Google Patents

Description

Oct 1933- H. HACKETT ET AL MACHINE GUARD Filed June 15, 1931 4 Sheets-Sheet l Oct. 10, 1933.

H. HACKETT El AL MACHINE GUARD Filed June 15, 1931 4 Sheets-Sheet 2 Fig.2

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MACHINE GUARD Filed June 15, 1931 4 Sheets-Sheet 3 ##acKe r W- WWI MW %S.

Oct. 10, 1933. HACKETT ET AL 1,929,687

MACHINE GUARD Filed June 15. 1931 4 Sheets-Sheet 4 Patented Oct. 10, 1933 MACHINE GUARD Henry Hackett, Selly Oak, Birmingham, and

Arthur Whittaker, Northfield, Birmingham,

England Application June 15, 1931, Serial Nathan, and

' in Great Britain June 24, 1930 1 1 4 Claims. (01. 192 -132) This invention relates to guards for machinery of the press type in which a reciprooatory part carrying one of a pair of tools co-operates with a stationary part carrying the other tool.

The object of the invention is to provide improved means for preventing injury to the hands of the operator while manipulating the work pieces which are placed between the tools. As is well known such machines are usually controlled by a pedal operated clutch, and the risk is always present of the machine being set in motion before the hands of the operator are moved clear of the tools. Many forms of guards have been devised for protecting the operator. In machines for stiffening the corners of cardboard boxes, to which our present invention particularly relates, a form of guard at present employed comprises a pair of hinged flaps which are arranged in combination with a stop adapted to control the clutch of the machinerand also a cam which controls the flaps. Immediately after the machine has been started the cam allows the flaps to swing outwards away from the tools. If the operators fingers are encountered by the flaps either the fingers are moved clear of danger or the flaps are jammed by the fingers-in which latter case the stop which controls the clutch causes the clutch to'be put out of action, and the further movement of the slide is consequently arrested. Experience has proved that this form of guard is not entirely satisfactory. In thefirst place it is not completely reliable, and in the second place a region between the tools into which a finger can be and often is inserted is left entirely unprotected By the present invention the disadvantages of this form of guard are obviated in a simple and convenient' manner.

The present invention comprises the combina tion with the reciprooatory part of the machine, of an independently and freely slidable part which is adapted to surround the sides and front of the tools, and levers connecting they said part with a clutch stop and a controlling cam, the mode of operation of the guard being as hereinafter described,

In'the three accompanying sheets of explanatory drawingsz- I Figure 1 is a front elevation, Figure 2 a sideelevation, and Figure 3 a'plan'illustrating one application of our invention to a press of the kind employed as above described in the manufacture of cardboard boxes. V

Figure 3c is adetail of a part of the arrangement shown in Figures 1 and 2.

Figure l is a sectional side elevation and Figure guard piece f.

5 a sectional end elevation illustrating the driving clutch of the press. V

Figure 6 is a detail view of theclutch elements. In carrying the invention into effect as shown,

we secure tothe front of the main guides 11 of the machine a pair of additional guides b between which is mounted a freely movable gravity operated slide A consisting in part of bars 0 carrying at their lower ends suitably arranged guard pieces d. The guard pieces are disposed to lie along the Q5 opposite sides of the reciprooatory tool 6 on the main'slide of the machine, and in addition another guard piece 7 is arranged to lie across the front of the tools, this guard piece being carried adjustably on one or. each of the other guard pieces.

Preferably'the adjustment of the front guard piece is made to depend on the adjustment of the lower fixed tool 9. In the example shown in the drawings the lower fixed tool g isslidable .horizontallyon'its supports it so that it can be adjusted to any required position. This adjustment is effected by a lever i pivoted at its upper end tothe machine frame and attached at its lower end tothe tool 9/. Sliding of the tool from one position to another is effected by mov-'- ing the lever. The work is supported on the front end of the tool gand the extent to which the tool projects beyond the supports it is varied to suit the size of the work pieces. When any adjustment of the tool g is made it is also necessary to adjust the position of the guard piece which moves over the front end of the tool g. To enable the adjustment of the guard to be effected automatically the guard is carried by a block :i movable in a slot in one side of the adjacent part d. Also the block :i is connected to the lever i by a rod is, so that movement of the lever for adjustment of the position of the tool 9 also causes a corresponding movement of the The freely movable guard slide is attached by means of a lever Z to a spindle m to which are respectively secured a lever n co-operating with the periphery of a cam 0 on the main shaft 1' of the press, and .a stop lever 10 whichlies in the path of a clutch controlling member q. The

said member is a known device consisting of a thin plate as shown carried on a shaft r. This plate is provided with a projection swhich in the position illustrated in Figure 5 is held by a lever v it which is connected by a rod 9: with the usual pedal of the press. On moving the rod as this lever is withdrawn for releasing the plate q. On release, the plate rotates and allows a clutch situated on the fly wheel t to engage the collar u on the shaft and so transmit motion to the shaft. The clutch is put out of action by re-engaging the plate. The plate :1 and clutch form no part of the present invention as they are ordinary features of the machine illustrated in the drawings. Our invention is concerned only with the means whereby the plate q can be re-engaged after release by the pedal for stopping the ma chine, in the event of the operatives hand being in a dangerous position. To enable the action of the plate q to be more readily understood we have, however, illustrated the clutch in Figures 4 and 5. In one face of the fly wheel is secured a plate y formed with an annular groove 2 of uniform depth. In the adjacent face of the collar u is secured a plate 2 formed with an annular groove the base of which is of wavy configuration. Between the two plates are mounted a number of balls 3 or rollers which lie in holes in'the plate q. A spring 4 bearing at one end against a stop 5 on the plate q and at the other end against a stop 6 on the collar it tends to'move the plate q relatively to the collar it. This movement is resisted when the plate q is held by the lever w. On release of the plate q by the lever w, the plate first moves under the action of the spring l so as to cause the balls or rollers, by riding up the inclined surfaces in the plate 2, to press against the base of the groove in the plate y. A driving connection is thus set up between the fly Wheel and the collar u on the shaft 1", and

motion is given to the shaft. After a complete revolution the projection s is again arrested by the lever to and this has the effect of releasing the clutch and stopping the machine. The plate q can also be held by engagement of the lever p with the projection 8.

When the machine is at rest the guard 00- cupies the upper position giving free access to the tools.

the space between the tools. The first effect of depressing the starting pedal is to release the clutch controlling member q and set the machine in motion. During the initial movement of the machine the guard controlling cam 0 allows the guard slide to fall freely across the space between Preferably, the driving mechanism of the machine is so arranged that when the machine is at rest the upper tool does not occupy its upper position but is moved to such position during the initial part of the motion of the machine. Therefore, while the guard is falling free- 1y across the tool space the upper tool is rising. Meanwhile, the clutch controlling member q is rotating towards thestop lever 11 connected with the guard. If the operators hand is in a dangerous position it will either be pushed aside by the guard or it will be trapped by the guard, in which latter case the guard cannot complete its free movement, and the stop lever p will engage the projections s and arrest the clutch controlling member and so stop the machine. Only when the guard has reached the lower limit of its free movement is the stop lever 13 clear of the clutch controlling member. Consequently, an operative movement cannot be given to the upper tool until the guard has reached its lower position. If for any reason the guard is prevented from reaching its lower position the stop lever prevents the normal action of the machine.

Seeing that the guard surrounds the front as well as the sides of the tool it is impossible for the guard. to complete its free downward movement if the hand of the operator occupies a dangerous position. It follows that by our present invention we are able to safeguard the operator completely andv in a manner which is free from mechanical complication or' risk of defective operation of the guard.

Although the invention has been described in connection with cardboard box making machines it is not limited thereto and is applicablcto other forms of presses. Also the invention is not limited to the example above described as subordinate mechanical details can be varied to meet different requirements.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is: A

1. In guards for machines comprising a reciprocatory slide, a movable tool carried thereby, a fixed tool situated beneath the movable tool, a rotary shaft for reciprocating the slide, a fiy wheel, a clutch for connecting and disconnecting the fiy wheel and shaft, and a clutch controlling memher which can rotate with the clutch and pedal operated means for controlling said member, the combination comprising a gravity operated slide arranged adjacent to the slide carrying the movable tocl, guard pieces carried on the gravity operated slide and arranged to surround the sides and front of the movable tool, a controlling cam on the said rotary shaft, a subsidiary shaft arranged parallel with thesaid rotary shaft, and three levers on the subsidiary shaft, one of them being connected to the gravity slide, another being associated with the controlling cam, and the third being arranged to act on the clutch controlling member, as and for the purpose described.

2. In guards for machines havinga fixed bed, a reciprocatory part, a fixed tool carried'by the bed, a movable tool for co-operating with the fixed tool carried by the reciprocatory part, driving mechanism including a source of motion for imparting movement to the recipro'catory part, a clutch for connecting and disconnecting the source of. motion and the driving mechanism, a controlling member for the clutch, a lever engageable with said member, and pedal in direct connection with said lever, the combination comprising a gravity operated slide, guards carried by the slide and arranged in association with the movable tool, a controlling cam actuated by the driving mechanism of the reciprocatory part, and three inter-connected levers, one of which is connected to the slide, another arranged to co-operate with the cam, whilst the third is arranged to engage the clutch controlling member of the machine when the guard is obstructed, substantially as described. I

3. A guard mechanism for a clutch-controlled press having a rotary shaft, comprising a gravity operated guard slide, a lever connected to the slide for imparting lifting movement thereto, a cam on the rotary shaft, a second lever co-operating with the cam to control the movement of the first mentioned lever, and a third lever arranged to disengage the press clutch should the descent of the guard slide be obstructed, all of said levers being mounted in co-related arrangement on a single, rotatable, subsidiary shaft arranged parallel to said rotary shaft.

4. A guard mechanism for a clutch-controlled press having a rotary shaft and movable and fixed tools, comprising a gravity operated guard slide carrying guard pieces on opposite sides of the movable tool and also carrying an adjustable guard piece situated across the front of the movshaft, and means connecting the adjustable guard piece with the fixed tool so that adjustments of the latter are accompanied by adjustments of the adjustable guard piece.

HENRY HACKETT. ARTHUR WHITTAKER.

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