US1184446A - Safety device for punch-presses. - Google Patents

Description

G. H. HAMlLTON.

SAFETY DEVICE FOR PUNCH PRESSES.

APPLICATION mm JAN. 3. i916.

Patented May 23,1916.

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a. H. HAMiLTONf SAFETY DEVICE FOR PUNCH PRESSES.

APPLICATION FILED MN. 3. 1915.

1,1 84 446. Patented May 23, 1916.

2 SHEETSSHEET 2.

GEORGE H. HAMILTON, 0F GRAND RAPIDS, MICHIGAN.

SAFETY DEVICE FOR PUNCH-PRESSES.

Specification of Letters Patent.

Patented May 23, 1916.

Application filed January 3, 1916. Serial No. 69,883.

To all whom it may concern:

Be it known that I, Gnonon H. HAMiLTON, a citizen of the United States of America residing at Grand Rapids, in the county of Kent and State of Michigan, have invented. certain new and useful Improvements in Safety Devices for Punch-Presses; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a safety appliance or device especially adapted for use in connection with power operated punch presses.

In a punch press the punching ram is mounted for vertical movements and moves toward and from the work operated upon, and in many instances after a piece of material has been operated upon the momentum of the moving parts of the press causes the ram to make an extra stroke or strokes after it should have stopped, and the operator, not expecting such movements on the part of the machine, will, in many cases, have introduced his hands under the ram and be caught thereby, accidents of this nature occurring very frequently.

It is the object and purpose of this invention to provide a mechanism which can be attached to punch presses of ordinary construction and which will serve to positively stop any extra movement of the ram over and above that desired, it being absolutely necessary for each downward movement of the ram that the operator perform an opera tion initiatory to the operation of the ram, otherwise it will not work at all. To this end I have provided the structure shown in the accompanying drawings which is de signed to accomplish the primary object of the invention described together with many other minor and subsidiary objects which have not been specifically enumerated but which will appear as understanding is had of the mechanismshown in the drawings.

Figure 1 is an enlarged section and plan taken substantially on the line 11 of Fig. 4. Fig. 2 is a side elevation drawn to the same scale as Fig. 1 of a detail of the mechanism. v Fig. 3 is a plan view showing my safety appliance applied to the punch press. Fig. 4 is a side elevation thereof; Figs. 5, 6 and 8 are side elevations of details of the mechanism; and Fig. 7 is a plan view of a detail of said mechanism.

Like reference characters refer to like parts throughout the several views of the drawings.

The punch press to which this device is applied is of ordinary construction having a suitable base from which project upwardly housing supports 1, one only of said supports being shown in the drawings. Suitable guides 2 are formed adjacent the front of the housing supports between which the ram 3 is mounted for vertical reciprocatory movements. A table 1: is supported by the base directly below the ram 011 which a suitable stationary die 5 may be secured, the companion die 6 being attaehed to the lower end of the ram 3. A shaft 7 is mounted at the upper end of and between the housings 1 having a wheel 8 secured thereto against which a stop element 9 engages, this element being mounted at the end of a lever 10 pivotally mounted between its ends at 11 to a stud projecting from a side of one of the housings 1. A weight 12 is adjustably mounted on the free end of lever 10 serving normally to bring the part 9 in engagement with the wheel 8. This may be any ordinary construction of any punch press of usual and well known design. The part 9 engaging with the wheel 8 usually has a projection adapted to insert in an opening in the wheel 8 so that when it engages with the wheel 8 the tendency is to stop the punch press at a certain particular portion of the movement of the ram, the power driving the press cutting out at the same time. Inasmuch as the driving construction is not any feature of the present invention it is not shown in detail, except what is necessary to illustrate its connection with my invention.

A foot lever 13 is pivotally mounted at the lower end of the base of the punch press and adjacent the rear thereof. A rod 1 f connected at its lower end between the ends of the foot lever 13 extends upwardly to the rear and at its upper end is secured to the rear end of an arm 15 loosely mounted on a stud 16 which projects outwardly from the side of the support 1. A strong coil spring 17 attached to this arm and to the support 1 normally tends to elevate it also elevating the foot lever 13 as will be understood. On the stud 16 are loosely mounted a star Wheel 18, and a ratchet wheel 19 side by side, these two 'wheels being suitably connected together so as to move in unison. A pawl 20 is pivotally mounted on arm 15 and is spring operated to engage with the ratchet wheel 19.

A lever 21 is pivotally mounted between its ends to a stud projecting outwardly from the side of support 1 at its rear end being formed with an upwardly extending pointed projection 22 adapted to engage between any two consecutive projections of the star wheel 18. Below the forward end of this lever an idle pulley 23 is mounted and a flexible connection secured to the lever 21 passes around this wheel extending upwardly and connected at its upper end to the lever 10 in front of its pivot 11.

A bell crank lever having a rearwardly projecting substantially horizontal arm 25 and a vertical arm 26 is pivotally mounted as shown to a stud 27 projecting from the support 1. The free end of this lever carries a weight 28 adjustable thereon and between the forward end of lever 21 and the arm 25 a tie 29 is positioned. In front of the bell crank lever and of the housing 1 and above the rear end of the base 4 a lever 30 is pivotally mounted between its ends, a link 31 connecting one end thereof with the upper end of the arm 26 heretofore de scribed. At the opposite end of lever 30 a clamping member 32 is rigidly secured projecting forward and having a companion clamping member 33 between which and the member 31 a vertical post 34: is secured. On the rear side of the housing support 1 a lever 35 is pivotally mounted between its ends, one portion of which extends back of the pivot and carries adjustably thereon a weight 36 while its opposite end is slightly widened and formed with an upwardly inclined part 37 at its upper edge forming a hook with an abrupt shoulder 38 a distance back of the front end as shown in Fig. 5. A notclr39 is made on the front edge of the lever 30 directly above the forward end of the member 35.

A rod 10 extends rearwardly from and is supported by the ram 3 being formed with a sleeve at its rear end in which is mount ed a vertical rod 41, the lower end of which in the downward movement of the ram enters a notch 42 in the side of member 35, thereby causing the member 35 to turn about its pivot depressing its forward end and elevating the weight 36.

In the operation of the mechanism, in order to start the punch press the operator must step on the end of foot lever 13 depressing it. When this occurs arm 15 is rotated about its pivotal mount and as pawl 20 engages with the ratchet wheel 19 it will be evident that the star wheel will have a partial revolution sufficient that one of the projections riding over the part 22 of lever 21 serves to elevate the forward end of lever 21 pulling on the flexible connection 24 and removing the member 9 from the part 8 thus freeing the mechanism for movement and, as is common in punch press constructions, connecting the power with the shaft 7 for the operation of the punch press. At the same time the arm 25 of the bell crank lever is elevated, the upper end of arm 26 being thrown forward to operate the lever 30 to dotted line position shown in Fig. 1 or to such a position that the hook at 38 may pass into the notch at 39 and hold the post 3 1 in rear position out from under the ram 3. WVhen the star wheel is rotated a partial revolution as the lever 15 is depressed pawl 20 rides against a pin 13 which projects outwardly from the housing support 1 causing the pawl to disengage.

from the ratchet 18. And it will be apparcut that the influence of the weight 28 will cause the projection 22 to always seat between two of the projections on the star wheel immediatelv after the lever 13 has been depressed, and the machine started in operation, the efiect of which will be to permit lever 21 to occupy its original position with the member 9 engaging against the wheel 8. Accordingly when the shaft 7 has made one revolution, the part 9 engaging therewith will tend to stop it and ordinarily if this stopping of the device occurs every time, no additional safety appliance would be needed. In practice, however, the momentum which the moving parts of the punch press have is so great that any projection on the part 9 extending into a depression in the part 8 is often broken or rendered useless, the shaft thereupon continuing its revolution, elevating the ram 3 and again carrying it down for further operation. In my device with the first downward movement of the ram 3, after an operation begins, rod 41 engages with lever 35 depressing the forward end thereof and disengaging it from lever 30 so that when the ram is elevated after the completion of one downward stroke, lever 30 is released, the weight 28 immediately throwing the post 34 under the ram sothat when a second downward movement of the ram is attempted it strikes against the post and is stopped. Accordingly after each operation of the ram it is necessary to depress the foot lever 13 before it will again operate and it is impossible to have an accidental downward movement of the ram except after a depression of foot lever by the operator.

Many changes in minor detail of construction will occur to others skilled in the art and accordingly I do not wish to be limited to the exact specific details of structure shown.

The appended claims define the invention and all modifications of structure falling within their scope are to be considered as comprehended by my invention.

1. In combination with a support, a vertically movable ram mounted on the support, means to operate the ram, a foot-lever pivotally mounted on the support, a post normally positioned under the ram, means operable by the foot-lever for withdrawing the post and simultaneously freeing the ram operating means, means for holding the post back of the ram during its down ward stroke, and means on the ram for engaging and operating said holding means on said downward stroke of the ram to free the post for return to normal position.

2. In combination, a support, a ram mounted for vertical reciprocatory movements thereon, means to operate the ram normally held in restraint, a lever pivotally mounted on the support, a post mounted on the support and movable back and forth with respect to the ram, means connected with the post for normally locating it in forward position under the ram and means operable by the lever for withdrawing the post to the rear position and simultaneously freeing the ram for one reciprocation, substantially as described.

3. In a punch press, a ram mounted for vertical reciprocating movements, means to operate the ram, a post movably mounted on the punch press adjacent the ram and normally located thereunder, a lever, means operable by the lever for moving the post from under the ram, a catch for holding the post in withdrawn position, means sinniltaneously operated by the lever for freeing the ram for reciprocation, and means on the ram engaging with the catch for freeing the post to return to normal position on downward movement of the ram.

at. An attachment for punch presses comprised of a lever pivotally connected to the support for the press, a stud projecting from said support, a ratchet and star wheel secured together and loosely mounted on the stud, an arm loosely mounted on the stud, a pawl on the arm engaging the ratchet wheel, a connection between the lever and arm, a pin extending from said support in front of the pawl, a lever pivotally mounted between its ends on the support and provided with a projection engaging the star wheel, a bell crank lever mounted on the support and having a weighted arm, a tie between said arm and the free end of the first lever, a notched lever mounted on and transversely of-the support, a connection between the bell crank lever and one end of the notched lever, a post attached to the opposite end of the notched lever, a latch lever pivotally mounted below said notched lever and having one end weighted and the opposite end hooked to enter the notch of the notched lever in one position thereof, a ram vertically reciprocable under which the post is adapted to locate, and a rod on the ram directly above the latch lever for e11- gaging therewith on downward movement of the ram.

5. In combination, with a support, a power driven ram mounted on the support for vertical reciprocatory movements, means to operate the .ram, a table below the ram, a device normally locating between the lower end of the ram and table to stop downward movement of the ram, means for simultaneously withdrawing said stopping device and freeing the ram for movement, means to hold said stopping device away from the ram while it makes one downward stroke, and means for automatically releasing said holding means to permit the stop device to take its normal position after one downward stroke of said ram.

6. In combination, with a power punch press, a safety appliance attached thereto including a stop device adapted to interpose between the am and the table of the press, a lever, means associated therewith for placing the press in operation, and additional means associated with and operated by the lever for withdrawing the stop device to inoperative position while the ram makes one operation, substantially as described.

In testimony whereof I affix my signature.

GEORGE H. HAMILTON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. 0.

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