US2681703A - Power operated presses, pressbrakes, guillotine shears, and like machines - Google Patents

Description

June 22, 1954 A H, CROUCHER 2,681,703

POWER OPERATED PRESSES, PRESS-BRAKES, GUILLOTINE SHEARS. AND LIKE MACHINES Filed Feb. 8, 1951 4 Sheets-Sheet l .27m/fafa@ /Inny /1/ franc/icl;

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'June 22, 1954 A. H. cRoucHER 2,681,703 POWER OPERATED PRESSES, PRESS-BRAKES, GUILLOTINE SHEARS, AND LIKE MACHINES Filed Feb. s, Y1951 4 sheets-'sneer 2 June 22, l954 A. H. cRoUcl-IER 2,681,703

POWER OPERATED PRESSES, PRESS-BRAKES. GUILLTINE SHEARS, AND LIKE MACHINES F11ed Feb. 8, 1951 4 Sheets-Sheet 3 June 22, 1954 H cRoUcl-IER 2,681,703

A. POWER OPERATED PRESSES, PRESS-BRAKES. GUILLOTINE Filed Feb. 8, 1951 SHEARS, AND LIKE MACHINES 4 Sheets-Sheet 4 Patented June 22, 1954 UNITED PATENT OFFICE POWER; `OPERATED PRESSES, PRESS-.g`

BRAKES;` GUILLOTINE SHEARSaAND LIKE MACHINES Antony'Harry Croucher, Esher, England Application` February 8,1951, Serial No. 210,061'` Claims.. priority, application Great Britain February 10," 1950 Thisinvention relates topower operated presses, press-brakes;A guillotine `sheai's-and like machines, hereinafter referred'to generally as presses. l

The invention consists broadlyin` presses, as hereinbefore dened in which `an hydrauliclink associated with a pump is interposed between the mechanical mechanism to which the power is applied directly from the prime'mover or indirectly through a flywheel actingas anenergy storer or accumulator and the Vblade-knifaor former beam or the likemeans or" the press.-

In this Way"overloadeprotection and substantial saving of material should-result At this point it` may be mentioned that itis an important feature of `the `invention that -thehydraulic arrangements do not necessarily entail the inclusion of a high pressure Vtype of hydraulic Dump.

The hydraulic power source incorporatedfcan also serve to provide power to actuate clutches and brakes and-the like, often `dealtvwithv `by ancillary pneumatic equipment: onz the` more powerful presses in .useftoeday Theneed for pneumatic bolsters and so forth alsowlargely dis appears, a considerable saving in= outlayzexpense onv toolingup` someclasses of` operations.- The need for an air compressor plant to feed the pneumatic equipment mentioned also, of` course, disappears.

The invention may .beeapplied to a singlecrank press or for a croppingor notchingmachine in which caseasingleram will beiemployedfas the hydraulic link.`

For a press` brake or. a guillotine `shear .thehy-` draulic linie will `comprisea plurality; normally two, rams. y

The accompanying drawings illustrate..fvarious embodiments `of this` invention in which:

Figure .l is an elevationA of asingle crank press,

Figure 2 Vis a vertical` section through the 4hy. draulic link shown in Figure 1,'

Figure 3 is a .vertical section thrcugh part of a pressubrake embodying two `hydraulic linksfand Figure 4 is azvertical.section.throughupartaof a guillotine embodying two hydraulic links-.1"

ln the embodiment illustrated in Figures. 1 and 2, the.. press compri-ses a frame AI having` awork-, ing tool 2 attachedfto'hydrauliclinkattached in turn to crank'zl, only thetipfofwhichfis shown. Thefcrankis kactuated by a-motor,-not-shown; which is alsoconneeted to iiywheel Eianddrives pump E by means of pulleyfdrive Ihthe pump ;being immersed inareservoir 8 `mounted atthe top of 'frame I.

24 Claims. (Cl. `1(i4'-86) The hydraulic link -3 Vcomprises a closed-cylinder `9 withinwhich slides piston Ill at one end of--hollow piston rodi I, the interior of which-is infccmmunication with space I2 in cylinder 9 `behind-piston I0. Workingtoolis attachedto `the other endof piston rod---I I.

`Linkl further compri-ses relief valve I3,com munic'ating withspace Min cylinder 9 in front of piston iikrelay valve I5 and locking valve -i ii, valves I3, I5and It beingintegraliwth'cylinder 9.-* Relay valve iii comprisesamovable member il #connected Vby link I8, multiplying lever I9, funk springt@ andnlinli-ZIV -with piston `rod `l I, while locking valve It comprises plunger "22 adapted to bear-upon member- Il and hold the same'in` the neutralposition shown in circumstances hereinafterdescribed.

Funk spring `2in comprises rod `23 `slidaloly engaged inuarm V2d integral'with cylinder 9, and

adjustable stop 25 is provided-to engage arm 26 attachedto pivot 2`l`of-multiplying lever i9, adjustment of stop 2 5 adjusting the working stroke of` the press.

Atm-the bottom.` of linkt, sump 28 fis ttedyattached to piston rod` i I, toreceivehydraulic fluid which may `leakfrom cylinder 9, and the `sump communicates with `reservoir -8 by' means ofconduit 29.- Suctionval-ves-S and- 3| are provided, communicating with the-spaces infcylinderS-in front of and behind piston iii-respectively and Withu'eservoir 8; to avoid cavitation within" cylinder l9 iduring operation.

Reliefwalve lI3fand locking valve `Iifare each of thebalanced pressure type,` and.A communicate onvone sidewith space Ill-by means of conduits 32uand 33 respectivelyf and onY the other side with pump: E` -bymeansof branches from conduit 3i, pressure-from pump G being supplemented `in-the case of relief `Vvalveii, by light spring 35; Conduit 36 from reservoir 8 serves valves {3,15 and 3`I,\while conduit 3c communicates also with valve I `5 by Way tof fa `non-return valve i 3l. Branches from conduit 38, which leads through piston rod II tospacel2=,lserveivalves BI and Ill-respectively.

In operation, during -adown-stroke, I piston :I will occupy a position. in` cylinder 9 predetermined by ltheisettingrof stop 25 and,.during the Apressing lort-cutting.operation,v member I1 will be. inthe neutral position as shown in Figure 2.' In the cou-rse 4o1? isuch operation,` the pressure in: :space I4 will greatly exceed that generated by pump 6, and l=will`= cause plunger V22110 `thrust downwards on `memberi'l to -hold Ithe latter `in the 4neutral position;

Should the press jam, or be arranged to give a coining effect, the pressure in space I4 will exceed that provided for by relief valve I3, and

fluid will escape to reservoir B by way of conduit 36, with consequent partial collapse of the link and relative upward movement of spring 2U. This movement during the down stroke will be accommodated by spring 2U because member II is prevented from moving up relative to cylinder 9 by plunger 22, so that relative upward movement of rod 23 is prevented by stop 25.

During the subsequent up or return stroke, tool 2 will be suspended from piston rod I I, with the result that the pressure in space Id will fall to zero, with consequent upward motion of plunger 22 and member I1 under thrust from spring 25. Such upward motion of member Il will establish communication between pump 5 and space I4 across valve i5 to restore piston IG to its original predetermined position. Overshooting is prevented because it would entail downward movement of parts 2i, 23, I9, IB, and hence of member Il, establishing communication across valve I5 between pump 6 and space i2 by way of conduits 34 and 38, this latter communication also making good any leakage which may arise from space l2 whilst piston rod II is suspending tool 2.

Sump 28, attached to piston rod II, slidably embraces cylinder s and is sealed by flexible membrane 39. Cylinder 9 is also provided with member di) for engagement with crank li.

In the press brake, part of which is illustrated in Figure 3, those members similar to those of Figures l and 2 are similarly numbered. The brake comprises two hydraulic links 3 and 3a attached to each side of working tool 2, but instead of utilising link 2| attached to piston rod II the linkage from the relay valve member I'I is taken through working tool 2 by way of saddles 4i. Two levers 42 and it are provided, pivoted at their centres to block i6 sliding on upright rod 45 secured to working tool 2, and sliding at their lower ends on saddles di, to form scissor arms cross-linking multiplying levers i9 to cause .these to move in unison. Further, in conjunction with hydraulic link 3a, dashpot 46 is substituted for funk spring 20 to smoothen the movements of relay valve members il, this dashpot having a restrictor 4'! and a non-return valve 48. Reservoir 6 and pump B are common between the two hydraulic links.

The guillotine, part of which is shown in Figure 4, is essentially similar to the press brake shown in Figure 3 except that provision is made for varying the position at which levers 22 and 43 are pivoted together, by forming internally racked slots 49 in these levers and passing a small pinion 5) through the intersection of the slots, the pinion being turned by locking handle 5I to alter the rake of working tool (knife) 2.

I claim:

1. In a mechanically actuated press provided with at least one hydraulic safety link between vthe working tool of the press and the thrustapplying part of the actuating mechanism, the

hydraulic safety link comprising a relief valve for limiting the thrust transmitted thereby to a predetermined value, means comprising a valve and a hydraulic pump, continuously driven when `the press is in operation, for restoring the hydraulic links to a working condition after operation of said relief valve.

24. A press as set forth in claim 1, wherein said pump is operatively associated with, suitably by immersion in, a fluid reservoir, the reservoir being Vconnected with said relief valve for the reception 4 of fluid from said hydraulic link when said predetermined value is exceeded.

3. A press as set forth in claim 1, wherein a relief valve is provided in association with the delivery side of said pump.

4. A press as set forth in claim 1, wherein said working tool is suspended from said hydraulic r link, and said restoring takes place in the course of a return stroke.

5. A press as set forth in claim 1, wherein the valve included in said means for restoring the link to a working condition is a relay valve comprising a hollow casing with connections to said pump, reservoir and to the cylinder of said link on each side of the piston thereof, and a valve member in the casing arranged to move from a neutral position in response to movement of said piston from a predetermined position in relation to said cylinder and thereby to effect appropriate communication between said connections for restoring said piston to said predetermined position in relation to said cylinder.

6. A press as set forth in claim 5, wherein said casing is integral with said cylinder.

'7. A press as set forth in claim 5, wherein said valve member is arranged to move longitudinally in said casing and is linked with said piston to follow its motion relative to said cylinder, at least when the latter is in the vicinity of said predetermined position.

8. A press as set forth in claim 7, wherein a multiplying lever is inserted in the linkage between said piston and valve member to magnify said relative motion, together with means such as a dead centre-type funk spring to accommodate such of said motion as is beyond said vicinity.

9. A press as set forth in claim 5, wherein said relay valve further comprises locking means responsive to overload pressure in said hydraulic link for preventing the operation of said relay valve during overload conditions.

10. A press as set forth in claim 9, wherein said locking means comprises a plunger responsive to overload pressure in said hydraulic link in a manner causing it to bear upon and hold said valve member in said neutral position during overload conditions.

l1. A press as set forth in claim 5, wherein a non-return valve is inserted in the connection between said pump and relay valve'to prevent flow from said relay valve to said pump. Y

12. A press as set forth in claim l, in which the relief Valve with which said hydraulic link is provided is of the balanced pressure type, one face of the valve being exposed to pressure within the link and another, larger face of the valve to pressure from said hydraulic pump.

13. A press as set forth in claim 12, in which said relief valve is provided with a light spring to supplement the pressure supplied by said hydraulic pump.

14. A press as set forth in claim 5, in which sudden movements of said valve member are minimised by operative connection of said member to a dashpot.

15. A press as set forth in claim '7, wherein two hydraulic links are provided, each having a relay valve, wherein the linkage set forth between the valve member of each relay valve and its associated hydraulic link is modified by cross-linkage so that the relay valve of each hydraulic link responds to relative movement of the piston and cylinder of the other hydraulic link.

16. A press as set forth in claim 15, .wherein said cross-linkage comprises two levers pivoted together, suitably at their centres, to give a scissor-like action.

17. A press as set forth in claim 15, wherein said working tool is a guillotine shear, and said cross-linkage is provided with means for varying the tilt of said shear.

18. A press as set forth in claim 17, wherein said means for varying the tilt comprises means for varying the position at which said levers are pivoted together.

19. A hydraulic link suitable for use in a press as a safety link, comprising a closed hydraulic,

cylinder, a piston slidably engaged in the cylinder, and a relay valve integral with the cylinder, the relay valve being connected or adapted to be connected with hydraulic fluid within said cylinder on each side of said piston, with a pump for the supply of hydraulic fluid under pressure, and with a reservoir for hydraulic fluid, the cylinder being provided with a relief valve, suitably leading to a conduit connected or adapted to be connected with said reservoir, the relay valve comprising an inner movable member linked with said piston to move from a neutral position in response to movement of said piston from a predetermined position in relation to said cylinder and, in so moving, to effect intercommunications within the relay valve appropriate, when the relay valve is connected as aforesaid, to restore said piston to said predetermined relative position said movable member and piston being linked by means comprising a spring adapted to accommodate movement of said piston beyond the vicinity of said predetermined relative position.

` 20. A hydraulic link as set forth in claim 19, wherein said means further comprise a multiplying lever for transmitting to said movable member in a magnied degree movement of said piston relative to said cylinder in the vicinity of said predetermined relative position.

21. A hydraulic link as set forth in claim 19 wherein said link further comprises a member responsive to pressure of hydraulic iluid in the link to hold said movable member in said neutral position when said pressure is equal to or in excess of that required to operate said relief valve.

22. A press as set forth in claim 1, wherein the valve included in said means for restoring the link to a working condition is a relay valve comprising a hollow casing with connections to said pump, reservoir and to the cylinder or" said link on each side of the piston thereof, and a valve member in the casing connected linkage to said piston so as to move from a neutral position in response to movement of said piston from a predetermined position in relation to said cylinder and thereby to effect appropriate communication between said connections for restoring said piston to said predetermined position in relation to said cylinder, said linkage incorporating adjusting means whereby said predetermined position can be varied.

23. A hydraulic link suitable for use in a press as a safety link, comprising a closed hydraulic cylinder, a piston slidably engaged in the cylinder and servo mechanism adapted, in response to movement of said piston from a predetermined position in relation to said cylinder, to establish communication between said cylinder and a source of high pressure hydraulic fluid to restore said piston to said predetermined relative position, the servo mechanism comprising a relay H valve having connections for hydraulic fluid within said cylinder on each side of said piston, with a reservoir for hydraulic uid, and having a connection with a source of hydraulic iluid under pressure, the cylinder being provided with a relay valve, and the relay valve comprising an inner movable member linked with said. piston to move from a neutral position in response to movement of said piston from said predetermined position.

24. A hydraulic link as set forth in claim 23, in which said linkage is adjustable to permit variation of said predetermined position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,808,606 Pels June 2, 1931 2,014,162 Benedek et al Sept. 10, 1935 2,249,149 MacMillin July 15, 1941 2,438,951 Stephens Apr. 6, 1943 FOREIGN PATENTS Number Country Date 254,376 Germany Dec. 5, 1912

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