US1906778A - Guard for presses and other like machines - Google Patents

Description

May 2, 1933. J. P. UDAL 1,905,778

GUARD FOR PRESSES AND OTHER LIKE MACHINES Filed July 15. 1931 3 Sheets-Sheet l EN/a1 ay 1933. J. P. UDAL GUARD FOR PRESSES AND OTHER LIKE MACHINES Filed July 15. 1931 3 SheetsSheet 2 Fig.2

y 1933. J. P. UDAL GUARD FOR PRESSES AND OTHER LIKE MACHINES Filed Ju 15. 1951 s Sheets-Sheet 5 Patented May 2, v1933 .Toim mummy when or "SELLY rink; simmers,

i dumronrmssss AND time are ai 'ncifi n med my 15, 19 1, Serial 115. 550,563, and a q a; Bgitaii mesa- 211930;

i invention 1 relates tow guards for presses and other like machines, including Stamps and hammers, and has :for its object to provide improved means for protecting 5 the hands of t the operatives against accidental injury.

Guards are already known in which a pair of principal parts are used, one of them being pivoted across the front of the machine- "so that it can be swung {outwards in the direction of i the operator, whi'lstthe other is pivoted ion the first mention'edfpar t and a is. likewise arranged to be "swung i outwards towards the. operator.'; In one form of such 7 guard both parts: are causedtoswing' con currently in each operationfof the pressor other machine, and in another form the mo.

tion is given first tothe second of the above mentioned parts, and, after this has" been 7 moved to the desired extent pboth parts are caused to move together. It" is, however, a

characteristic feature of such guards that motion isi'given to both parts in each opera tive movement ofthe, press or the like.

' A "disadvantage of these guards; is,

especially when applied to hih speed maic'hines,*that owing toinertia e ects theyare subjected to considerable stresses, and Icon-- sequentl'y they must to'be' ver well de- 0 signed and constructedhto" Wit'stand the forces tdwhichtheyare subjected; A fur-- ther disadvantage is that these guards make a considerable movement towards the -oper ator ineachstroke; which is inconvenient,

inthis guard.- Alsoya'scthe number of times the hand of; theoperator is encountered. by

the guard is very small in comparison with v the number "-of--mov ements given: to the guard, the greater partof the workidone in I moving the guard serves nous'eful purpose.

There is need; therefore; for a guard which, whileitperfo'rinsits' main: purpose of re: movin'g the hand from d nger when the normally orilyfa s'malr. movement iwhieh' is little imo're than-sufficient to prevent the Irrth'eQthree accompanying sheetsiof ex-f; e

and this movement'is reduced to a; minimum ,while' the e v bracket 2.

necessity aris'esgand consequently in this con dit'ioii makes; a eonsiderable' movement; has i danger zone motion. I The invention c0mpri esthe combination j of a primary guard part pivoted onthefr'naaft r the press been set in l'novingportion' ofthe machine; the arrangement beingsuch that normally the secondary part only'is ,moved by the niach'ine the primary part remaining stationary; but in I the event o'fthe opera-torshand being caught betweenthe two parts of theguard, motion is given to: the primary partifrorn thesecOndary part through the medium of the entrappedhand,ifor the purpose of carrying the latter out of danger.=- I

Figure 1 is a' front elevation and Figure c 2 a side' elevation showing inuthe, inner positiona press guard constructed in accord-a an'ce withjthis' invention. Figure 3 is an end View showing the guard in the extended or outer position. i i

In carrying the invention into, efiect as 'shown'in Figures: 1-3, I secure by means of brackets a atthe frontofth'e machine ona freely pivoted cross-shaft a the upper ends ofa pair of depending side arms b which are joined by one or more horizontal bars a. These-form the primary partrof the guard; The said part is'held in a convenient position across thelfront of the press or-the like under the action of azspring d or by gravity, this position being determined byv'the abutment of an adjustable stop an on the shaft a against one of vthe brackets .a. a The primary partof the guard oiily-moves when the'necessity arises; Normallyit remains at rest; It will'be seen fromthe drawingsjhatone end of :the. spring bears against the stop w other end is secured to the At a convenient position on the side arms b of the primary part of the .guard'is arrangedanother cross-shaft e, and onthis' are carried a pair of shorter side'iarms f joined b'yhorizonta'l members g forming-the sec- 100 ondary part of the guard. This part normally swings about the axis of the shaft 6. At the lower part of the arms f is provided a horizontal hand striking member h, and also a like member 1' is arranged across the lower ends of the arms I), the gap between these members h, i, being such that any obstruction of the thickness of the operators finger will not allow the secondary part of the guard to pass through the primary part and complete its normal movement. The normal movement of the secondary part of the guard is through the aperture in the primary partwhich gives the operator access to the tools j of the machine. As is usual the moving tool is fixed on the lower end of the vertical slide of the machine and the fixed tool is mounted on the bed Z.

Motion is given in each operation of the machine to the secondary guard part through any convenient lever or link mecl1- anism connected to the secondary guard part and to any suitable part of the machine such as the crank shaft or plunger. Preferably a crank m is attached to one end of the crank shaft n or other convenient rotating shaft, and this is connected through a link 0 to a pair of interconnected levers p, g freely mounted on the cross-shaft'a. In the example illustrated the lever p is attached to an extension of the boss of the lever q, the part of the lever 37 which embraces the said extension being split and secured by a screw 3 The parts p, Q can be adjusted relatively to each other by releasing the screw y. Motion is taken from the lever g through a link 1" to one of the side arms f of the secondary guard part. By mounting the levers p, g coaxially with the shaft w an advantage is obtained in that it allows the whole guard to be conveniently adjusted relatively to the front of the machine. The normal or initial position of the guard is determined as already mentioned by a stop m, which is adjustably secured to the shaft a and is arranged to abut against one of the brackets 2. When it is required to cause the initial position of the guard to be nearer or further from the machine than is shown in the drawings the stop as is suitably adjusted.

In each action of the machine the secondary guard part is caused to swing relatively to the primary part (which remains stationary) for the purpose of closing the aperture in the primary part and so preventing access of the operators hand to the tools during the active stroke of the machine. This action is illustrated by the full and dotted lines in Figure 2. Normally no movement is given to the primary part of the guard and the secondary part-moves between the position indicated by the full and dotted lines. Should the operators hand be in the way it is caught between the lower horizontal members h i, of the primary and secondary guard parts. As the hand thus prevents further relative movement of the said parts, both parts move together against the action of the controlling spring (I or weight, and the hand is carried away from the dangerous position as shown in Figure 3. For normal purposes the movement of the secondary guard part can be a comparatively small one, but when the hand is trapped a large movement of the two guard parts is desirable, and the various members of the mechanism are advantageously proportioned and arranged. in any convenientmanner such as that illustrated to satisfy thisrequirement. An important feature of the design of the guard is the disposition of lever g and link 0' relative to each other and lever f. The arrangement is such that in the early part of the stroke of the guard the first small angular movement of the lever 9 causes a relatively larger angular movement of the lever f, whereas later in the stroke the angular movement of the lever q is very much larger than that of the lever f, which at the end of the stroke is hardly moved at all. This result is obtained because the. upper lever g and its link 2" form a toggle, and the angle between is at the maximum at or near the end of the guard movement.

It will be apparent from the foregoing that in guards constructed in accordance with my invention only the smaller or secondary part of the guard is normally moved in each action of the machine, and the amount of movement given to this part is then little more than sufficient to prevent the hand from entering the danger zone while the machine is in motion. In the event, however, of the hand being in the dangerous position when the machine is started, the hand itself serves to interconnect the guard parts and so cause an ample movement to be given to the main guard part for carrying the hand clear from danger. The larger part of the guard, therefore, only comes into action when the necessity arises. The hand is also pulled out for the same reason if caught between the secondary part of the guard and the lower die of the tool of the press. As soon as the secondary part encounters an obstruction ofany kind both guard parts move together and risk of trapping the hand between the secondary part of the guard and a fixed part of the machine is thereby obviated.

The invention is not limited to the example above described, and subordinate details can be varied to suit different requirements. I desire to emphasize, however, that the mechanism shown in the accompanying drawings is to be preferred as it enables the required motions of the guard parts to be readily obtained in a manner which is coni I claim as new and desire to secure byLeti i veniently applicable to many different forms of existing machines. 7 Having thus described my invention what ters Patent is In press and like machine guards, the comblnatlon of a primary guard part, a

cross shaftcarrying the upper end ofthe v 1 said part, controlling means acting on said partya secondary guard part pivoted on the 1 primary part, a source of motion, and actuat ing means for transmitting movement to the :secondary part from the source of motion,

said means comprising a'pair' of relatively adjustable interconnected levers mounted co- I axially with the cross shaft, a link connecting one of the levers to the source'of motion, and a linklconnecting the other lever directly to the secondary part intermediate its upper and lower ends thelatter lever and link forming a toggle for impartingfa large angular movement to the primary part in the event of the operators hand being i caught between the two (partsof the guard, substantially'as describe r In testimonylwhereofiI have signed my name to this specification.

JOHN POUNTNEY UDAL.

Images