US2335917A

US2335917A - Fluid-operated press

Info

Publication number: US2335917A
Application number: US444724A
Authority: US
Inventors: Cuthbert Robert Alexander
Original assignee: Broom and Wade Ltd
Current assignee: Broom and Wade Ltd
Priority date: 1941-06-05
Filing date: 1942-05-27
Publication date: 1943-12-07
Anticipated expiration: 1960-12-07

Description

Patented Dec. 7, 1943 UNITED STATES PATENT e mc t;

' 2,335,917 I v FLUID-OPERATEI! raEss land, assignor' to Broom and Wade Limited, High Wycombe, England, a British company Application May 27, 1942,"Serial No. 444,724

In Great Britain June 5, 1941 18 Claims. -(Cl'. 60- 97) This invention relates to power presses for performing any desired particular operation such for example as riveting, punching, shearing, actual pressing or otherwise, of the type in'which the press includes a power piston working in a power cylinder to actuate a piston rod or ram which transmits the actual force to perform the necessary work, the press being operated by a liquid under a high working pressure (such as supplied from an intensifier), and has for its main object to provide such devices of an extremely efiicient and simple form.

As is well known, in the majority of presses it is not necessary for the power piston and its rod,

ram or the like to transmit a high working force throughout the whole of its stroke, but it is sufiioient if the maximum force is exerted for a desired proportion of the stroke at its conclusion; in other words, the total stroke can be divided into what may be termed the approach portion (requiring but slight force) and the working portion (requiring the full force).

The present invention has for its object to provide means by which the power piston and parts connected therewith can be movedfor the approach portion of the stroke without the pres sure liquid acting upon the power piston for the purpose, the said pressure liquid then acting upon the power piston to carry out'the working portion of the stroke.

In general, presses in accordance with the invention are provided with asubsidiary cylinder of smaller diameter than the power cylinder in which works a subsidiary piston directly or indirectly connected with the power piston and its rod, ram or the like, the arrangement being such that the approach portion of the stroke is effected by the pressure liquid acting upon the subsidiary piston to move it and the power piston, and the construction including automatically operated valve means whereby when the approach portion of the stroke is eiiectedthe pressure liquid is caused to act upon the working face of the power piston for the performance of the "working portion of the stroke.

The automatically operated valve means can have various constructions and be operatedin accordance therewith. In most forms, however.

stroke terminates then the continuedpressure' of the pressure liquid on the subsidiary piston causes the parts to move to the other extreme position and by this slight movement, a suitable partor parts effect the opening of a valveto allow the pressure liquid to pass to the power cylinder'and operate upon the working face of the'power piston. When the workng portion of the stroke has been effected, upon the return'of the-parts this spring acts to bring the parts oi the connection into their original position. i I Preferably the construction is such-thatthe power cylinder is filled on both sides of the power piston with the working liquid, a passage oripase sages being provided through the power'piston or from end to end of the power' cyli'nderto enable the said liquid to pass from side to side'iof the power piston during the approach portion of the stroke, but having means combined therein an automatic manner by the same .mean'sras way of example only and in whichthat which opens the valve for supplying .thezliq uid under pressure to act uponthe power piston;

Additionally. and by preference, a reservoir or compensating chamber may also be providedfor the working liquid in connection-with thexpower cylinder. This suitably communicates with-the power cylinder. and by preference on the side-re mote from that in which the working face of the power piston forms a boundary.

, As will be realised, many constructions may be adopted for carrying the invention into effect and presses in accordance with the invention'may be fixed or portable, in any case, especiallythe 1atter case, if desired the intensifier being separate from the-press proper. 1

In order that the invention may be better understood it will now be described with reference to the accompanying drawing, which isgivenby Fig. 1 shows in elevation one structural meth: od of carrying the invention into efiectjpartlytin section with the power piston at the -upper {end of its stroke.

Fig. 2 shows a fragmentary portion of 1, but with the power piston in. the.position," iust after the commencement of the power stroke and some parts shown in modified form. 1' I.

"In the drawing, 3 is the power cylinder hav-v ingone integral closed end 4 which is apertured respondingly threaded bore of one arm of a yoke l I of any usual construction, the parts being held in position by a locknut l2. The other arm of the yoke carries one of the dies or the like I3, the other die [4 being carried on the end of the piston rod 9.

The cylinder 3 has an exterior jacket Hi thereon which abuts a flange It at one end with the interposition of suitable packing. The other end H extends beyond the end 4 of the cylinder 3 and abuts a clamping plate ill with the interposition of packing forming the exterior flange of anairfilled rubber cushion it of hollow annular V- shaped section.

A thrust sleeve is also comes around a portion of the subsidiary cylinder 5 to abut at one of its ends with suitable packing the end 4 of the cylinder 3, and at the other end the interior flange of the cushion IS.

The plate I! is apertured and held on the cylinder 5 by a nut in screw-threaded engagement with a screw-threaded portion on the end of the cylinder 5 which projects through the said plate [1.

By the shape and construction of the parts a space 2| is left between the exterior of the cushion IS, a portion of the interior of the jacket l5 and the outer surface of the end 4, which space constitutes a liquid reservoir. The exterior of the cylinder 3 has between itself and the interior surface of the jacket l5 a number of passageways 22 which communicate on the one hand by conduits 23 with the space 2| and on the other hand through apertures 24 with the interior of the cylinder 3.

25 is the power piston working in the cylinder 3, which is not connected directly to the piston rod 9 but through the following mechanism.' Secured to its rear is a sleeve 26 by means of a flange, this sleeve on the interior having two diameters. The larger diameter is in the portion adjacent the piston 25 and is a close sliding fit on an enlarged portion 21 on the end of the piston rod 9. The smaller diametered portion is in the nature of a flange 28 the interior diameter of which is a close sliding fit on the piston rod e, the step between the two diameters of the piston rod forming a limiting abutment for the flange 28. The enlarged portion 21 has a recess 21 therein and between this recess and another recess 29 at the rear of the piston 25 is located a compression spring 3%) of suitable strength. The arrangement is such that normally there is a certain distance between the actual end 3| of the enlarged portion 2'! and the actual surface 32 at the rear of the piston 25. In certain conditions, however, these surfacescome into contact. When held separate by the spring action 35, the space between the surfaces 3i and 32 communicates with the interior of the cylinder 3 below the piston 25, by means of apertures 33 in the sleeve 26. The arrangement between the parts, however, is such that theseapertures are closed by the exterior surface of the enlargement 2! when the piston 25 contacts by its surface 32 with the surface iii of the enlargement 27 (Fig. 2)

The subsidiary cylinder 5 has working therein a subsidiary piston 3% which is formed hollow and at its front has a stepped flange 35 secured by suitable screws to the piston 25. The flange 35 has apertures 36 therein. The piston 34 has fixed therein an inner tubular member 3? terminating towards the piston 25 at a desired distance therefrom in a notched seating Further, the piston 3d at its front has a reduced stepped aperture, the upper portion 35 forming a seating for a ball (-0 constituting a valve coming at the upper end of a projecting rod M secured conoentricaliy in the enlarged portion 2'5 of the piston rod.

The recess 28 in the piston 25 open to the front of the piston 25 through an annuiar passageway The whole arrangement is such that in the position shown in Fig. 1 communication exists between the two sides of the piston That is to say, from the lower side the. oil is free to pass through the aperture 33, the recess 29, the passageway 42 and the apertures 36 to the front of the piston.

When, however, the surfaces 3! and 32 are in contact (Fig. 2), then this pasageway is closed and even before the surfaces SH and 32 come into contact any passageway through the apertures 33 is closed.

In this position, however, the ball 45 is either closely adjacent or in contact with the notched seating 38. This does not prevent pressure liquid passing through the member til and the notches, to act upon the upper surface of the piston 25.

The complete action readily will be appreciated; When the pressure fluid is permitted to pass to the tool, by valve control from an intensifier or the like through the hollow piston 34, the parts are in the position shown in Fig. 1 and consequently the said fluid is precluded from acting upon the surface of the piston 25 as it cannot pass the ball valve Gil. Consequently it acts upon the subsidary piston 3:3 by exerting pressure on the tubular end thereof and upon the surface of the ball it. This is sufficient to perform the approach portion of the stroke dur ing which period oil with which the system is filled readily passes from the lower side to the upperside of the piston 25 and also from the lower portion of the cylinder 3 (through the passageways 23) to the reservoir 2i.

When, however, the die it encounters its major resistance, then by continued action through the piston 34 and the piston 25, the sleeve 25 slides over the enlarged portion 2'! and by its portion of smaller diameter 28, over the piston rod 8.

The result is, the surfaces 3! and 32 are brought together, closing the passage through the piston 25 for the oil and the ball valve E2 is removed from its seat 39. As a consequence, the oil coming from the intensifier passes through the hollow member 3'! and the notched seating 38 to and through the apertures 38 in order to act upon the upper surface of the piston 25, and thus the pressure fluid exerts its effect through the large area of the said piston, to accomplish the purpose of the tool, such for example as riveting.

The return stroke is effected by a compression spring $3 on the under side of the piston 25, which surrounds the sleeve 26 and rod 9 and during this return stroke the requisite amount of oil which comes above the piston 25 is returned to the intensifier. Further, when the pressure conditions are satisfied during the return stroke the spring 3!] again separates the surfaces 3| and 32 to bring the parts into the position shown in Fig. 1.

As will be appreciated, the air-filled cushion I8 automatically compensates for the varied volume of comparatively incompressible fluid supplied to the space 2| duringthe action of the tool.

The upper portion of Fig. 2 indicates a variation of the structurefor the air-filled cushion and. shows two air-filled hollow ring 44, although only one such ring could be employed, or more than two, 'or in some cases such rings'could b replaced by hollow balls, or otherwise. I

Such a construction, however, modifies the arrangement for securing the clamping plate I! into position and in the construction shown in Fig. 2 this plate I! takes the form of a stepped plate having additional packing members cooperating with its outer and inner contacts with the structure.

In some cases the air-filled cushion on the interior of the press can be replaced by a freely sliding piston arrangement with or without a return spring, and further where required the reservoir for the fluid could be in a separate chamber fixed to the tool, for example at one'side thereof, or separate therefrom.

Whatever form may be adopted, it willbe understood that as the Volume of the portion of the power cylinder behind the power piston decreases, pressure liquid therefrom automatically passes to the chamber or reservoir, the variation in volume of which is permitted by the air-filled cushion, spring-pressed piston, or otherwise.

It will be realised that the mechanism for operating the automatic valve means may be made in many other manners. For example, the power piston could be fixed to its piston rod or ram and spring means could be included between the end of the subsidiary piston and the power piston which, for the approach portion of .the stroke would transmit the pressure from the subsidiary piston to the power piston but which would be compressed for the working portion of the stroke, during which compression the valve means provided would be opened to give free. passage of the pressure liquid from the subsidiary cylinder to the power cylinder, to operate upon the working face of the power piston.

The invention is not limited to the precise forms or details of construction described, as these may be varied to suit particular require- 1 ments. 7 r

What I claim and desire to secure by Letters Patent of the United States of America is:

1. In a machine of the character described, the combination of a cylinder, a power piston in the cylinder, a tubular auxiliary piston fixedly connected with the power piston, a closure for the and responsive to impact of said means on a tubular piston, a' conduit for admitting pressure cylinder, a tubular auxiliary piston fixedly connected with the power piston, a closure for the tubular piston, and means movable relatively to movement resisting element for opening the closure and admitting pressure fluid through the 'tubular auxiliary piston to the power piston.

4. In a machine of the character described, the combination of a cylinder, 2. power piston in the cylinder, a tubular auxiliarypiston fixedly connected with the power piston, a closure for the tubular piston, a tool supported by'the power piston movable relatively thereto, and means responsiveto impact of said tool on a movement resisting element for opening said closure andadmitting the pressure fluid through the tubular auxiliary piston to the power piston.

5. In a machine of the character described, the combination of a cylinder, a power pistonin the cylinder, a tubular auxiliary piston fixedly connected with the power piston, a closure for the tubular piston, a conduit for admitting pressure fluid against said closure to impart movement to both of said pistons, and means supported by the power piston and movable relatively to the same and responsive to impact of said means on a movement resisting element for opening said closure and admitting the pressure fluid through the tubular auxiliary piston to the power piston, said power piston, auxiliary piston, closure and impact responsive means forming a self-con tained structure as such insertible into and removable from thecylinder.

6. In a machine of the character described, the combination of a cylinder containing pressure fluid, a power piston in the cylinderya tubular auxiliary piston fixedly connected with the power piston, a closure for the tubular auxiliarypiston, a conduit for admitting pressure fluid against said closure to impart movement to both of said pistons, and means on the power piston independent of the pressure fluid and responsive to impact on a movement resisting element for openingthe closure and admitting the pressure fluid through the tubular auxiliary piston to one side of the power piston, the power piston having a passage therethrough controllable by the-impact responsive means for the flow of the pressure fluid through said piston from the opposite side of the piston. '7. In a machine of the character described, the combination of a cylinder containing pressure fluid, a power piston movable in the cylindena tubular auxiliary piston fixedly connected to the power piston, a closure for said tubular auxiliary piston, a conduit for admitting pressure fluid to said cylinder, the closure being adapted to ob struct the flow of pressure fluid from said conduit into the cylinder, a toolsupported by the power piston movable relatively thereto, and means responsive to impact of said tool on a movement resisting element for opening the closure and admitting the pressure fluid through said tubular auxiliary piston to one side of said power piston,

,the power piston and auxiliary piston having communicating passages therethrough which are controlled by said means to establish communication b tween o h s es f the ow r p ston an auxiliary piston connected thereto,

, 3. In a machine of the character described, the combination of a cylinder, a power piston mo able in the cylinder, a tubular auxiliarypiston fixedly connected with the power piston, a closure for the tubular piston, a conduit for admitting pressure fluid against said closure to impart movement to both of said pistons, a tool supported by the power pistonmovabl relatively thereto and responsive to impact on a movement resisting element for opening the closure and admitting pressure fluid through the tubular auxiliary piston to the power piston, a passage through the power piston, said tool being adapted to obstruct the flow of fluid through said passage from one side of the piston to the other during a portion of its movement relative to the piston.

9. In a machine of the character described, the combination of a cylinder, a power piston movable in the cylinder, a tubular auxiliary piston fixedly connected with the power piston, a closure for the tubular piston, a conduit for admitting pressure fluid against said closure to impart movement to both of said pistons, a tool support by the power piston movable relatively thereto, a fluid passage through the power piston, and means responsive to impact of said tool on a movement resisting element for obstructing said passage while permitting continued movement of said power piston relatively to said tool.

10. In a machine of the character described, the combination of a cylinder, a power piston movable in said cylinder, a tubular auxiliary piston fixedly connected with said power piston, a closure for said tubular auxiliary piston, a conduit for admitting pressure fluid against said closure to impart movement to both of said pistons, impact responsive means for opening said closure and establishing communication between said conduit and one side of the power'piston, the cylindercontaining pressure fluid on both sides of the power piston, a reservoir for pressure fluid outside said cylinder, a compressible element within said reservoir, and means for conveyin pressure fluid forced by movement of the power piston in the cylinder from the latter into the reservoir against said compressible element.

11. In a machine of the character described, the combination of a cyiinder containing fluid, a power piston movable in said cylinder, a tool supported by said power piston and movable relatively thereto upon impacting a movement resisting element, means for admitting pressure fluid into the cylinder upon encounter of the impact responsive tool to the movement resisting element, a reservoir, a compressible and expansible volume compensating element within said reservoir, means for conducting fluid forced from said cylinder into said reservoir and for compressing said compressible volume'compensating thereby, passages for directing the pressure fluid expelled from said cylinder by movement of the piston into said reservoir, and a compressible element located in said reservoir and adapted to compensate by its volume reduction effected by the incoming fluid, for the increase in fluid volume in said reservoir.

13. In a machine of the character described, the combination of a cylinder, a power piston movable in said cylinder, an auxiliary tubular ,piston fixedly connected with said cylinder in axial alinement therewith, an impact responsive tool supported by said power piston and movable relatively thereto, a conduit for admitting pressure fluid to the cylinder, a valve for said auxiliary tubular piston supported by said impact responsive tool, and resilient means interposed between said power piston and said impact responsive tool for normally maintaining the latter in predetermined relation to the power piston and for retain ng the valve in closing position with respect to said cylinder.

lfl. In a machine of the character described, the combination of a cylinder, a power piston movable in the cylinder, an auxiliary tubular piston fixedly connected with the power piston, a conduit for admitting pressure fluid to said cylinder, said tubular auxiliary piston being guided in said conduit, a valve normally obstructing flow of pressure fluid through said tubular auxliary piston, an impact responsive tool slidably carried by the power piston and supporting said valve, whereby, upon impact of said tool, said valve is raised from obstructing position, and a spring interposed between said power piston and said tool for normally retaining said tool in preetermined relation to said power piston.

15. In a machine of the character described, the combination of a cylinder, a power piston movable in said cylinder, a conduit means for admitting pressure fluid to said cylinder, a tubular auxiliary piston fixedly connected to said power piston and movable in said conduit means, an impact responsive tool, an apertured sleeve on the power piston slidably supporting said irnpact responsive tool, a valve in said auxiliary piston normally obstructing the flow of pressure fluid into the cylinder, the tool supporting sleeve having apertures therein communicating with passages extending through the piston and said impact responsive tool being adapted upon encounter of a movement resisting element, to open the valve and obstruct the apertures through said sleeve, and subsequently to close the passage through said piston.

16. In a machine of the character described, the combination, as set forth in claim 11, in which the compressible and expansible volume compensating element within the reservoir is formed by a hollow, air filled resilient member.

' 17. In, a machine of the character described, the combination, as set forth in claim 11, in which the compressible and expansible volume compensating element within the reservoir is formed by a hollow annular member filled with air.

18. In a machine of the character described, the combination, as set forth in claim 11, in which the compressible, expansiblevolume compensating element within the reservoir is formed by an annular trough member of V-shaped crosssection and made of resilient material.

ROBERT ALEXANDER CUTI-IBERT.