US2429065A - Safety device for presses - Google Patents

Description

Patented Oct. 14, 1947 UNITED STATES PATENT OFFICE SAFETY DEVICE FOR PRESSES Joseph M. Korkowski, Minneapolis, Minn.

Application September 22, 1943, Serial No. 503,361

15 Claims. 1

This invention relates to improvements safety devices for punch presses and similar machine tools.

In the ordinary punch press the punch is moved toward and away from the bed or die, usually in a vertical plane, to operate upon the work placed in or on the die, by means of a connection to an overhead crankshaft. Obviously where the work is put in place by hand there is great danger to the operators fingers and hands from the descending punch. In operation, the punch is raised by the crankshaft, drawing the punch up to a top, dead center position and after the work is put in place, the press is tripped, causing the crankshaft to make one complete revolution moving the punch downward against the work and back up to idleposition.

It is customary to provide the press with some form of safety device such as cords which are fastened to the operator's hands and upon which a pull is exerted, as the punch moves downward, in order to withdraw or retract thehands from the vicinity of the punch and die. However, all such safety devices of which I am aware have had the disadvantage that the extent of such retraction movement, or the length-to which the cords are pulled, has been exactly proportional to the distance through which the punch moves in its downward or working stroke. In other words, a considerable range of travel of the punch in the downward direction has occurred before the hands are pulled or retracted from the immediate vicinity of the punch, and it has been noted from actual experience that the hands all too frequently are not entirely in the clear before the punch has reached the work. In the case of careless operators, and particularly where the nature of the work is such that it projects above the die face into the path of the punch, this has resulted in injury to one or more fingers of the hands.

It is the primary object of my invention, therefore, to provide a safety device of this nature but wherein the very initial movement of the punch is made effective to accomplish the complete retraction or pulling of the hands from the vicinity of the punch, the balance of the movement of the punch through its working and return strokes having no further retraction effect on the hands. As a result, the operators hands will be well in the clear before the punch reaches the danger point with reference to the die.

Another object is to provide a safety. device of this character wherein the cords attached to the operators hands are lightly heldtaut by weights at all times but which are otherwise free to permit the operator to move them about at will except that, when the punch is traveling near the die, the hands cannot reach a dangerous position with respect thereto. Such arrangement further provides that, unless the hands are in a dangerous position, the operation of the safety device will not be apparent to the operator. Thus if the operator withdraws his hands in time, the cords will not jerk or otherwise disturb him, but should he fail to get his hands in the clear the operation of the safety device will positively pull the cords to retract the hands.

Another object is to provide a device of the foregoing characteristics which is of simple and practical construction and capable of being readily applied to the press.

These and other more detailed and specific objects will be disclosed in the course of the following specification, reference being had to the accompanying drawings, in which- Fig. 1 is a side view of a punch press equipped with my safety-device, and showing the positions assumed by the parts when the punch is at its top or idle position.

Fig. 2 is an enlarged fragmentary vertical sectional view through a lower part of the safety device, showing the arrangement of the weights and lower end of the vertical slide member.

Fig. 3 is an elevation of the structure shown in Fig. 2.

Fig. 4 is a horizontal cross section along the line 44 in Fig. 3.

Fig. 5 is an enlarged fragmentary detail View of the gear and rack arrangement, showing the parts in the positions assumed when the retraction movement of the hands is almost completed.

Referring now more particularly and by reference characters to the drawing, A represents the punch or movable member of a conventional form of punch press B, the punch being supported at its upper end portion by means of a bearing C upon the crank D of a crankshaft E. Rotation of the crankshaft E obviously will cause the upper end pitman-like portion of the punch A to travel a circular path and will cause the punch to move upwardly and downwardly at its lower end toward and away from the die F, or other work, placed upon the bed G of the press.

In practice the punch has a normal idle position wherein it is raised to its fullest from the work and from which, when the press is tripped, the punch first'moves downwardly on a power or turn stroke. The crankshaft E makes a complete revolution for each such operation.

My safety device comprises a frame represented generally at l0, which is conveniently and inexpensively fabricated from ordinary piping and couplings, and which comprises an upper horizontal portion ll secured in any suitable manner at one end 12 to the press B near an upper end thereof. Said upper portion H extends outwardly over the operators station in front of the press. The outer end of the upper frame portion H is then supported by an upright stand member I3 which at a lower end is secured by a flange member I4 to the fioor I5. This stand member may support the operator's seat [6 by means of a bracket H, the operator when at work being thus seated between the stand member and the press, and forwardly of the latter.

The upper frame portion Il may, forthe sake of rigidity, comprise a pair of pipes arranged in parallelism and secured by T-couplings 18 to the upper ends of similar parallel pipes forming the upper part of the stand member l3. At the point I9, Fig. l, the double pipe construction may end and by means of elbows 20 and a T-coupling 2! be brought to fit a singl stand pipe 22 as seen in Fig. 3.

A rack member or slide 23 is supported on the upper frame portion 1 I by means of suitable slide bearings 24 so that the member may be reciprocated horizontally and lengthwise of the frame portion ll. At the end nearest the press B the rack member 23 is pivoted at 25 to an end of a drive member or connecting link 26 which comprises a tubular portion 21 interiorly tapped to receive a rod 28 which is screwed therein and locked in position by lock nuts 29. The end of the rod 28 is then pivotally attached at 30 to the pitman end of the punch A, the connection being here shown as conveniently made by means of a plate 3|, carrying the pivot 38, secured beneath the screws 32 holding the cap of the bearing C in place. The overall length of the drive member 26 may obviously be adjusted as required to fit the device to a press of any usual length of stroke and it will be evident that the operation of the punch will cause the rack member 2-3 to be reciprocated in its bearings 24. As the punch A starts its motion from the idle position, as shown in Fig. 1, the rack member 23 will be moved outward or forwardly, and as the crank D travels the first quadrant in its circular path the rack member will reach its furthermost outward or forward movement. Continued travel of the crank D will then begin to pull the rack member 23 back toward the press and it will of course return to its initial position when the punch reaches idle position again.

The rack member 23 intermediate its ends has a series of gear teeth 33 projecting slightly below the lower edge of the member, as clearly shown, and which cooperate with a partially toothed segment gear 34. Said gear is supported beneath the rack member 23 for oscillation thereby by means of a shaft 35 and suitable bearings 33 secured to. the upper frame portion ll. At each side of its partially toothed circumference the gear 34 has angularly formed slide surfaces 37 and 38..

Mounted on the shaft 35 alongside the segment gear 34, to turn therewith, is a larger segment gear 33 and this gear meshes with an upright rack member 43 having a toothed edge 4! for this purpose. The rack member 43, or slide, is supported for up and down movements with respect to the stand member [3 of the frame It by means of slide bearings 42 which support the rack member from the side of the stand member facing the press B.

The rack member 43 of course moves in a plane passing alongside the first rack member 23, permitting these parts to clear each other.

In the normal position of the parts, with the punch in its raised and idle position, the rack member 23 rests with its teeth 33 just beginning to mesh with the gear 34 and the rack member 40 stands at its highest position. Now, as the punch starts its operation, the crank D moving over forwardly causes the rack member 23 to be moved outwardly and the engagement of the gear teeth will oscillate or rock the gears 34 and 33 in a clockwise direction as viewed in the drawing. This action moves the rack member 43 downwardly as will be apparent.

As the motion continues the parts reach the position shown in Fig. 5 and the various leverages and lengths of the toothed portions of the parts are so selected that this condition occurs before the crank D has traveled its first quadrant or quarter revolution from top, idle position. As the crank continues to move the teeth on the rack member 23 will then clear the teeth on the gear 34 and as this occurs the slide surface 31 will have reached about a horizontal position whereat it will slidably engage the underside of the rack member 23 permitting it to slide on in its forward stroke, without turning the gears which are in fact locked against further movement at that time by the engagement of the slide surface with the rack member.

When the rack member 23 reaches its limit of travel in this direction and reverses its movement, due to the continuation of the crank D in its travel, the member will slide across the gea 34 until the end tooth 33 reengages the teeth on the gear whereupon the gears will be rocked back in the opposite direction, or counterclockwise as shown in the drawing. As the rack member 23 thus reverses the punch A is on its downward or working stroke but the aforesaid sliding movement of the rack member before reengagement of its teeth 33 with gear 34 maintains the gears 33 and 39, and of course the rack member 30, in locked position until the punch has reached nearly its lower limit of travel.

As the punch then reaches its, lowermost position the gears 3,4 and 39 are rocked back to start- 1 positio s. and the rack teeth 33 will finally clear the teeth of the, gear 34 bringing slide surface. 38 up intoposition for sliding engagement with the rack member 23. as the punch travels upwardly. When the punch approaches starting position again the rack member 23 will be moved back in the opposite direction finally coming to rest with the teeth 33 again just in mesh with the gear 34 ready to start another cycle of operation.

It will be seen from the foregoing that I provide a connection such that only the initial movement of the punch from top idle position operates the rack member 40 in the downward d;- rection, whereupon the parts are locked until the punch reaches the lowermost part of its movement at which time the rack member 40 is moved back upwardly to starting position and locked until ready for the next operation. The reengagement of the rack teeth 33 with the gear 34, after each described disengagement, is ensured by the fact that the teeth depend orproject below the lower edge of the rack and thus must engage the end teeth of the gear each time. It is, of course, this disengagement and reengagement of the rack member 23 and gear 34 which permits only these parts of the movements of the former to be used for oscillating the gears, which are useful for my purpose.

. Th downward movement of the rack member 40 is used to draw the operators hands clear of the press as will now be described. Below the lowermost slide bearing 42 the rack member 45 carries a cross member or cross head 43 to the ends of which upright slid members 44 and 45 are secured in spaced relation. These slide members 44 and 45 move upwardly and downwardly within guides 45 and 41 which may be as shown secured to and depended from the lower slide bearing 42 down to a point near the floor l5. The guides 46 and 41 take the form'of channels of U-shaped cross section (Fig. 4) adapted to nicely receive and guide the slide members 44 and 45, and the channels are open on the sides facing the press B. The inside webs or flanges of the channel shaped guides 46 and 41 are cut away from the points 48 (Figs. 2 and 3) up to near their upper ends in order to clear the cross head 43 as the rack member 40 moves up and down.

The slide members 44 and 45 have upright passageways or bores 49 and 50 opening through their upper and lower ends and above and in alignment with these passageways pulleys 5| and 52 are journaled on the guides 46 and 41 by means-of pins 53, said pulleys being located clear of the slide members at their uppermost positions. A cord or flexible connecting member is provided for each hand of the operator, and are indicated at 54 and 55. At one end each cord is provided with means for attachment to the hands, such as the straps 56, and at their other ends the cords 54 and 55 are passed over the respective pulleys 5| and 52 and thence downwardly loosely through the passageways 49 and 50. The lower ends of the cords 54 and 55, below the slide members 44 and 45, are secured to upper ends of threaded rods 51 and 58 and upon these rods weights or stops 59 and B ar placed and held from downward displacement by means of nuts BI and 62 threaded on the rods. The upper ends of the rods and 58 may freely enter the respective passageways 49 and 50 as clearly shown, and the guides 46 and 41 also act as guides for the weights 59 and 60 to hold the parts in proper alignment for this'purpose.

In operation, the hands of the operator may be moved toward the press until the pull on the cords 54 and 55 draws the weights 59 and 60 up against the lower ends of the slide members 44 and 45. With the rack member 40 in its normal elevated position the nuts BI and 62 are then adjusted to the point that the cords will permit the hands to reach the press for placing the work thereon. Then as the rack member 40 is moved downwardly, by the press starting its working motion as, previously described, it will be evident that the slide members 44 and 45 will bear downwardly on the weights 59 and 59, which thus act as stops, and will pull upon the cords to draw or retract the hands away from the press. The hands will be held against return toward the press until the rack member 45] again moves upwardly, as will 6 the clothing or the like, while the spreading of the cords, provided by the spacing between the slide members 44 and 45, causes the cords to nicely clear the sides of the operator seated on the seat It.

By virtue of the constant light tension upon the cords 54 and 55, and their running engagement with the slide members 44 and 45, it will also be apparent that should the operator withdraw his hands from the press of his own volition, then the weights 59 and 64 will drop below the slide members and the downward movement of the latter as the press is operated will have no effect on the cords. Thus, so long as the operator is careful and keeps his hands in the clear, the safety device will have no perceptible effect on his hands. But should he negligently start the press in operation before his hands are clear then the weights, or stops will necessarily be in position for engagement to pull the cords and forcibly Withdraw the hands.

Attention is directed to the fact that it is the very initial movement of the punch from its uppermost idle position which is used to carry out the complete retraction movement of the hands. The various gears are so proportioned and arranged'that the first few degrees of movement of the crank D, less than the first quadrant of its circular path, will rock the gears to their furthermost position and push the rack member 40 down as far as it goes. Thus the punch will have descended but little before the hands are entirely in the clear and the punch cannot have reached a dangerous proximity to the hands and work. As seen in Fig. 1 this effect may be increased by stopping the punch a little short of dead center on its return stroke, for example by a distance indicated at X. Now as the punch starts each operation it will actually first move upwardly and then back downwardly while operating the rack member 23 to withdraw the hands and the parts may then be so proportioned that the hands will be completely in the clear before the punch actually descends below its idle position as will be understood.

It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Havin now therefore fully illustrated and described my invention, what I claim to be new anddesire to protect by Letters Patent is:

1. The combination with a punch press having a punch and a pitman connected thereto and movable at an upper end in a circular path fro-m an upper idle position downwardly through a working stroke and return, of means for withdrawing an operators hands from the vicinity of the lower end of the punch during said working stroke of the punch and pitman, comprising flexible members for attachment to the hands, and a member adapted and arranged to be pushed endwise outwardly from the press in response to the initial movement of the upper end of the pitman from its idle position through substantially the first quadrant of its circular path and operative to pull upon the said flexible members and ible members for attachment to an operators hands, means for pulling upon said members to pull the hands away from the lower part of the punch member as it moves downwardly, the said means bein operative in response to the movement of the said upper end portion of the pitman toward its working stroke, and the said pitman being adjusted to stop short of a top dead center position on its return stroke whereby the said means will be operated by the initial travel of the pitman over said top dead center position to pull the hands into the clear before the punch member has traveled more than a fraction of its downward working stroke.

3. A safety device for a punch press havin a punch and a pitman connected to the punch and arranged for movement at an upper end in a circular path from an upper idle position downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of an operator for pulling the hands away from the punch as it descends, means connected between the upper end of the pitman and the said flexible members for pulling upon the latter as the punch descends, and the said means being operative to transmit the said pull to the flexible members only during substantially the first quadrant of the circular path of the pitman from its upper idle position.

4. A safety device for a punch press having a punch operating pitman arranged for movement at an upper end in a circular path from an upper idle position downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of an operator for pulling the hands away from the punch as it descends, means connected between the upper end of the pitman and the said flexible members for pulling upon the latter as the punch descends, and the said means being operative to pull upon the flexible members during the first quadrant of the circular path traveled by the pitman as it leaves the upper idle position, to hold said flexible members against opposite movement until the punch substantially completes its downward travel and to release the flexible members for the remaining movement.

5. A safety device for a punch press having a punch and an actuating pitman arranged for movement at an upper end in a circular path from an upper idle position downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of an operator for pulling the hands away from the punch as it descends, means connected between the upper end ofthe pitman and the said flexible membersfor pulling upon the latter as the punch descends, and the said means including a gear mechanism, which operatively meshes only during the initial and latter parts of the working stroke of the pitman.

6. A safety device for a punch press having a punch and a connected pitman arranged for movement at an upper end in a circular path to move the punchfrom an upper idle position' downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of any operator for pulling the hands away from the punch as it descends, means connected between the upper end of the pitman and the said flexible members for pulling upon the latter as the punch descends, and the said means including a gear mechanism operative to establish a connection to 8 the said flexible members for pulling upon the same only during the first movement of the punch from idle position and to establish a connection for freeing the flexible members as the punch approaches its lowermost position.

7. A safety device for a punch press having a punchand a pitman arranged for movement at an upper end in a circular path to move the punch from an upper idle position downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of an operator for pulling the hands away from the punch as it descends, means connected between the upper end of the pitman and the said flexible members for pulling upon the latter as the punch descends, and thesaid means including a gear mechanism operative to pull upon the flexible members as the punch moves away from idle position, to lock the flexible members against opposite movement as the punch travels toward the lower range of its working stroke, and to release the flexible members as the punch reaches its lowermost position.

8, A safety device for a punch press having a punch and a pitman arranged for movement at an upper end in a circular path to move the punch from an upper idle position downwardly through a working stroke and upwardly through a return stroke, comprising flexible members for connection to the hands of an operator for pulling the hands away from the punch as it descends, means connected between the upper end of the pitman and the said flexible member for pulling upon the latter as the punch descends, and the said meansincluding a rack arranged for reciprocation by the upper end of the pitman as it travels its circular path, a gear for operation by the rack and operatively arranged to pull upon the flexible members as the rack moves in one direction and to release the members as the rack moves in the opposite direction, and said gear being only partially toothed so that only the initial movements of the rack in the first direction and intermediate part of the final movement in the opposite direction will actuate the said flexible members.

9. A safety device for a punch press having a punch and a pitman arranged for movement at an upper end in a circular path and to move the punch from an upper idle position downwardly through a working. stroke and upwardly through a return stroke, comprising flexible members for connection to. the hands of an operator for pulling the hands away from. the pitman as it descends, means connected between the upper end of the, punch andv the said flexible members for. pulling upon the. latter as, the punch descends, the. said means including a rack arranged for reciprocation by the upper end of. the pitman as it. travels itsv circular path, a segment gear having a toothed portion adapted to be moved in one direction by meshing engagement with the rack as itstarts. its movement in response to the travel of the punch from idle position, toward its. working stroke andv to; be moved i-nthe opposite direction by the rack as it returns toward starting position in response to. the approach of; the. punch to. its lowermost position, the. said toothed portion of the. gear being adapted to move out of meshing engagement with the rack, between the.

aforesaid movements thereof and the gear having, surfaces for engagement by the rack to lock the gear against movement. except when in mesh with the rack, and means operative to pull upon and to release the said flexible members in response to the said opposite movements of the gear.

10. A safety device for punch presses, comprising a rack member operatively arranged for reciprocation as the punch travels, a segment gear meshing with the rack member and adapted to be intermittently oscillated thereby, a gear connected to said gear segment, a second rack member meshing with the gear for reciprocation thereby, and cords operatively connected to said second rack member and adapted to be pulled upon and released by the opposite movements thereof, the said cords being adapted for connection to the hands of an operator for pulling the same from the vicinity of the punch.

11. A safety device for punch presses, comprising a rack member operatively arranged for reciprocation as the punch travels, a segment gear meshing with the rack member and adapted to be intermittently oscillated thereby, a gear connected to said gear segment, a second rack member meshing with the gear for reciprocation thereby, cords adapted for connection at one end to the hands of an operator of the press, the other ends of the cords having sliding engagement with the second rack member, and stop means on said other ends of the cords for engagement by the said second rack member as it moves in one direction to thereby exert a pull upon the cords for drawing the operators hands away from the punch.

12. A safety device for punch presses, comprising a rack member operatively arranged for reciprocation thereby as the punch travels, a segment gear meshing with the rack member and adapted to be intermittently oscillated thereby, a gear connected to said gear segment, a second rack member meshing with the gear for reciprocation thereby, cords adapted for connection at one end to the hands of an operator of the press, the other ends of the cords having sliding engagement with the second rack member, and stop means on said other ends of the cords for engagement by the said second rack member as it moves in one direction to thereby exert a pull upon the cords for drawing the operators hands away from the punch, the said stop means on the cords being also adapted to act as weights to hold the cords taut between the hands and the said prising a member movable in one direction as the punch of the press moves toward the work and movable in the opposite direction as the punch moves away from the work, a pair of cords adapted at one end for connection to the hands of an operator of the press, the said cords being slidably associated with the said member, weights on the cords to hold them taut, and the said member being adapted to engage the said weights to exert a pull upon the cords as it moves in one direction and thereby to pull the hands away from the punch as it moves toward the work,

14. A safety device of the character described, comprising a member supported for movement in upward and downward directions, at least one flexible member adapted at one end for connection to the hand of an operator and at its other end slidably engaging the said member and hanging therefrom, and a stop member on the hanging end of the flexible member adapted for engagement by the lower end of the member as it moves downwardly to thereby exert a pull upon the end of the flexible member connected to the hand.

15. A safety device for punch presses, comprising a member movable in upward and downward directions adjacent to the press, a pair of cords adapted for connection at one end to the hands of an operator and at their other ends having stop members for engagement by the said member as it moves downwardly to thereby pull the hands away from the press, the said ends having free sliding engagement with the said member and the stop members acting as weights to hold the cords taut, and the said stop members being adapted to descend as the hands are withdrawn away from the press by the operator and to hang clear of the lowermost position of the movable member so long as the hands are well clear of the press.

JOSEPH M. KORKOWSKI.

REFERENCES CITED 'The following references are of record in the file of this patent:

UNITED STATES PATENTS

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