US3817080A - Safety-bolster - Google Patents

Abstract

An over-load control for a bolster plate to be positioned on the ram portion of a press, wherein, the device includes a cavity pressureized by a controlled fluid pressure for supporting the bolster plate with means to relieve the pressure upon over-load, said pressurized system being self contained in the bolster plate.

Description

United States Patent 1191 Zupan, Jr. et a1;

[5 1 SAFETY-BOLSTER [76] Inventors: Benjamin J. Zupan, Jr.; Leonard S. Zipp, Jr., both of 1 1090 Abbey Rd,

both of North Royalton, Ohio 44133 [22] Filed: Apr. 7, 1971 211 Appl. No.: 131,982

[52] US. Cl 72/432, 72/441, 100/53 [51] Int. Cl. 321d 55/00 [58] Field Of Search 72/432, 453, 441; 100/53; 192/150 [56] References Cited UNITED STATES PATENTS 1,773,439 8/1930 Rode 72/432 2,890,669 6/1959 Williamson 72/432 2,936,055 5/1960 Kassnel 72/432 [4 June 18, 1974 2,998,238 8/1961 Kenline 72/432 3,481,171 12/1969 Alexander 72/432 3,487,772 1/1970 Kraft 1 1 100/53 3,583,201 6/1971 Topaz 72/432 FOREIGN PATENTS OR APPLICATIONS 1,177,006 8/1964 Germany 100/53 Primary E.vaminerCharles W. Lanham Assistant Examiner-Gene P. Crosby 5 7] ABSTRACT An over-load control for a bolster plate to be positioned on the ram portion of a press, wherein, the device includes a cavity pressureized by a controlled fluid pressure for supporting the bolster plate with means to relieve the pressure upon over-load, said pressurized system being self contained in the bolster plate.

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ATTOENEV SAFETY-BOLSTER This invention relates to safety apparatus for preventing damageto a punching or cutting machine by overloading the frame and shafts as a result of faulty transfer ofmaterial through the dies, misalignment, or other accidents and more particularly to a safety bolster plate, wherein the supportingmedium is a hydraulic fluid arranged with controls for providing a movement of the plate when certain predetermined overload conditions are encountered.

An important object of this invention is to provide a tool support capable of shifting and relieving an excessive load on the machine frame said support having apparatus therein which measures the force thereon and operates at a predetermined loading.

Spring trip devices are known in the art for releasing tolling or moving parts of a machine as a means of pre venting damage to the machinery frame and mechanical parts. The apparatus which forms the preferred embodiment of our invention utilizes hydraulic principals and becomes part of the machine itself thus making it operable at all times irrespective of the tooling on the equipment. Further the system does not rely on springs pressure sufficient to hold the same against normal machine loadings. When a fault occurs and the machine loading exceeds a normal limit the pressure in the bolster plate rises and is automatically relieved which allows the plate to shift thus reducing the load on the machinery frame. The control apparatus for the hydraulic circuit includes a shut-off for the machinery.

Accordingly, it is an important object of this invention to provide a bolster plate for a punch or shear machine wherein the working surface is maintained in operative position by the action of hydraulic pressure relievable upon a predetermined excessive stress of the plate.

Another importantobject of this invention is to provide a bolster plate for a press-type machine wherein the working surface of the bolster plate is carried by a hydraulic fluid said bolster plate including an oil pump and pressure regulating apparatus for maintaining a constant and predetermined support pressure for the bolster plate.

An important object of this invention is to provide a tool support capable of shifting and relieving an excessive load on the machine frame said support including apparatus which measure the force thereon and operates at a predetermined loading.

Other objects and advantages more or less ancillary to the foregoing, and the manner in which all the various objects are realized, will appear in the following description, which considered in connection with the accompanying drawings, set forth in the preferred embodiment of the invention. In the drawings:

FIG. 1 is a top plan view with parts cut away for purposes of clarity;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a side view with cut-away portion showing an alternate bolster plate in section;

FIG. 4 is a sectional view taken along line 4--4 of FIG. 1; and

FIG. 5 is a front view.

Referring first to FIG. 1, the safety bolster device is shown therein having an upper plate 10 substantially rectangular in shape'and having a central opening .12 formed therein. The opening 12 threadably receives a sleeve 14 extending downwardly from the upper plate 10. Thesleeve 14 is provided with a cylindrical opening 16 formed there through.

The sleeve 14 is threadably mounted in plate 10 as at 18. The upper plate 10 provides a surface on which the tooling is carried by the punch press (not shown) for operation with the press ram there above.

The safety bolster assembly includes a lowerplate. 20 on which the upper plate 10 is slidably mounted said upper plate 10 being vertically reciprocable in'respect to the lower plate 20. Upper plate 10 has a depending rim 22 which is slidably on a wall 24 formed on the bottom plate 20. O-ring seals are provided around the periphery of the inner wall of the rim 22 and the wall 24 of the lower plate 20 and provide a fluid-tight seal there between. The lower plate 20 is provided with a cylindrical opening 28 for slidably receiving sleeve 14. O-ring seals 30 in the lower plate 20 engage the outer surface of the sleeve 14 and provide a fluid-tight seal between the sleeve 14 and the lower plate 20.

The lower plate 20 has a circular shoulder 32 confronting a circular shoulder 34 formed on the sleeve 14, said shoulders providing a stop which limits the vertical movement of the plate 10 in respect to plate 20 and in respect to the machine. When the shoulder 32 and 34 are in contact, a cavity 36 results between the upper plate 10 and the lower plate 20 said cavity 36 being filled with hydraulic oil contained! therein by the seals 26 and 30. When the hydraulic fluid is applied to cavity 36 under pressure the upper plate is moved to its operational position wherein the soulder 32 and 34 are in full contact.

A chamber 38 is formed in the lower plate 20 and is utilized as a reservoir for containing hydraulic'fluid said chamber 38 providing a sump for receiving oil from the cavity 36 and supplying oil as required for introduction into the cavity 36 during the operation of the bolster plate.

. A fluid passage 40 as shown in FIG. 2 opens to the cavity 36 beneath the top plate 10 and above the lower toward the seat 44. Aplug 52 threadably mounted in the lower plate 20 provides for adjusting the bias on said spring and thereby achieve an adjustment of the pressure of the fluid in the cavity 36 which will urge the ball 46 off the seat 44 and allow the passage of hydraulic fluid from the cavity 36 to the bore 54 which carries the spring 50 and the ball 46. The bore 54 opens through a port 56 to the reservoir 38 thus providing a fluid circuit from the cavity 36 to the reservoir 38. Plug 52 has an O-ring seal 58 at the forward end thereof which engages the bore 54 and prevents the passage of fluid through the threaded section of the bore 54.

An electrical conductor 60 is connected to seat 44 at one end and at the other endis joined to one pin 62 of electrical connector 64. Pin 66 of said connector 64 is grounded tolower plate 20. The ball 46 acts as a normally closed switch when it is in the seated position. Upon actuation thereof and being lifted off the seat 44 by pressure in the cavity 36, the circuit is opened and a connection from the conductor 64 may be made to the machine controls for stopping the machine upon actuation of the ball 46 off the seat 44.

The piston 68 is slidably in a cylinder sleeve 70 and carries a pair of O-rings seals 72. Actuation of said piston 68 in one direction increases the fluid pressure in the cylinder bore 74. An inlet check valve 76 carries a ball 78 biased against a seating a spring 80, said check valve 76 being in a passage 82 which provides a conduit for the hydraulic fluid to the pump 74 from the valve bore 54 and the reservoir 38. Acutuation of the piston 68 away from the check valve 76 results in hydraulic fluid flowing into the pump cylinder and being ejected through passage 84 upon a return stroke of said piston 68 in the opposite direction, said fluid being ejected through the passage 84 to the cavity 36 by way of passage 40 between the upper plate and the lower plate 20. A ball check valve 86 in the passage 84 obstructs the flow of the fluid from the cavity 36 to the pump 74, a ball 88 being biased against a seat by a compression spring 90. Reciprocal movement of the piston 68 alternately takes hydraulic fluid from the reservoir 38 and ejects it into the cavity 36.

Piston 68 is connect through a link 92 to handle 94 which is pivotally mounted on the lower plate by a pin 96. Angular displacement of the handle 94 results in reciprocal movement of the piston 68 thus allowing the operator to pump up the pressure in the cavity 36 by actuation of handle 94.

A pressure gage 98 is hydraulically connected to the cavity 36 and provides the operator with an indication of the pressure therein and the available force on the plate to hold the same in position against the force of the ram or other normal machine stresses. I

Having thus described this invention in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carrying out this invention, we state that the subject which we regard as being our invention is par ticularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above speciflcally described embodiments of the invention may be made without departing from the scope of the invention as set forth in what is claimed.

What is claimed is:

l. A safety bolster plate comprising an upper plate vertically reciprocable on a lower plate, fluid seal means between said plates operable with said upper and lower plates to form a fluid-tight cavity, fluid reservoir means, pump means connected to said fluid reservoir and said cavity for pressurizing the fluid in said cavity, stop means on said upper and lower plates for limiting relative movement therebetween in one direction, the pressurized fluid urging said plates against said stop means, and pressure-controlled valve means for limiting thevfluid pressure in said cavity, said fluid being vented to said reservoir when the pressure in said cavity is raised to a predetermined point by a load on said upper plate.

2. The apparatus of claim 1 wherein said pressure controlled valve means comprises a spring loaded ball valve having a manual means for pre-adjusting the loading on the spring.

3. The apparatus of claim 2 wherein an electrical circuit is opened by the actuation of said ball valve, said circuit controlling the operation of the machine and stopping same upon actuation of the safety bolster plate.

4. The apparatus of claim 3 wherein gage means is carried by said lower plate and indicates the pressure of fluid in the cavity between the plates.

5. The apparatus of claim 1 wherein electrical circuit means is opened by the actuation of the pressure controlled valve means.

6. The apparatus of claim 1 wherein said stop means comprises a shoulder on said sleeve opposite to the upper plate, said lower plate having a shoulder confronting said sleeve shoulder, said shoulders contacting to provide a positive stop limiting the travel of said plates as pressure is applied to the fluid in the cavity.

Claims (6)

1. A safety bolster plate comprising an upper plate vertically reciprocable on a lower plate, fluid seal means between said plates operable with said upper and lower plates to form a fluidtight cavity, fluid reservoir means, pump means connected to said fluid reservoir and said cavity for pressurizing the fluid in said cavity, stop means on said upper and lower plates for limiting relative movement therebetween in one direction, the pressurized fluid urging said plates against said stop means, and pressure-controlled valve means for limiting the fluid pressure in said cavity, said fluid being vented to said reservoir when the pressure in said cavity is raised to a predetermined point by a load on said upper plate.

2. The apparatus of claim 1 wherein said pressure controlled valve means comprises a spring loaded ball valve having a manual means for pre-adjusting the loading on the spring.

3. The apparatus of claim 2 wherein an electrical circuit is opened by the actuation of said ball valve, said circuit controlling the operation of the machine and stopping same upon actuation of the safety bolster plate.

4. The apparatus of claim 3 wherein gage means is carried by said lower plate and indicates the pressure of fluid in the cavity between the plates.

5. The apparatus of claim 1 wherein electrical circuit means is opened by the actuation of the pressure controlled valve means.

6. The apparatus of claim 1 wherein said stop means comprises a shoulder on said sleeve opposite to the upper plate, said lower plate having a shoulder confronting said sleeve shoulder, said shoulders contacting to provide a positive stop limiting the travel of said plates as pressure is applied to the fluid in the cavity.

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