US2360060A - Hydraulic press - Google Patents

Description

omu 10,1944. l.. NERSEN 2,360,060

HYDRAULIC PREss l l Filed Aug. 6, 194]. .3 Sheets-Sheet 2 ToPRE-F/LLER 37 3,0

` Oct. 10, 1944.

L. IVERSEN HYDRAULIC PRESS Filed Aug. 6, 1941 5 Sheets-Sheet 3 To PRESSURE CYLINDER Efj-.

To Put.;- BA ck CYuNoERs 9 10 To PREfFlLLER INVENTOR Lorenz Aye/"Sen madw BRA m: HORSE' Powe-R y use.

on the line III- III of Figur l; l

Patented oci. 1o, :1944

nynaauucrnnss Lorenz Iverson, Pittsburgh, Pa., assigner to Mesta Machine Company, Pittsburgh, Fa., a oorporation of Pennsylvania Application August o, 194i, serial No. 105,639

(ci. s0-52) 2 Claims.

This invention relates to hydraulic presses'. It provides a novel mechanism whereby the ilexibility of operation is greatly increased with marked improvement in output. Material simpliiication ,of the installation and, in certain cases, very substantial reductions in cost are also obtainable.

Heretofore hydraulic presses, particularly in the larger sizes, have been eithery of the socalled steam hydraulic type or the straight hydraulic type with reciprocating pumps. In

the. steam hydraulic type, the hydraulic pressure is produced by intensifiers receiving pressure from steam boilers. In the straight hydraulic type, several'rnotoror steam-driven reciprocating pumps are connected in parallel to the press cylinders. press head is obtained by cutting the press cylinders in or out, the line pressurebeing constant at all times. In these prior presses, theA press head is raised by auxiliary hydraulic cylinders called pullbacksJ Idle strokes are effected by the force of gravity which comes into play when the pressure on the pullback cylinders relieved.

The presses `iust described .have` very little flexibility and their output has been seriously limited. They are necessarily designed vfor the heaviest work and are correspondingly slow. On lighter work vthey operate at a speed far less than the ability of the workmen to manipulate the workpiece. 4

In my improved system, I depart entirely from the principle of the old style press systems and employ pumps of the vcentrifugal type which are without positive displacement in contrast t the intensiers and reciprocating pumps` in 'common I arrange these pumps in series and in this fashion and with the related structures herein described, I have been able to use them with entire success and with the improvements in operation above noted. I am able to obtaina variable line pressure by employing the pumps in. series-and by using pumps having the characteristic of' delivering maximum pressure at shut-0E (zero capacity), I can obtain a very rapid press operation. I

In the accompanying drawings illustrating c. present preferred Aembodiment of the invention:

Figure 1 is a top plan view of a hydraulic press` and its fluid-supply system;

Figure 2 is a front elevation of the press per se;

Figure 3 is a vertical section to enlarged scal In both types, variable pressure of the p Figure 4 is a diagram showing the control system; and

"Figure 5 is a chart showing the characteristics of one of the pumps employed; i

Referring first to Figure 2, there is shown a hydraulic press having a base 2 and a head 3 con nected by vertical' posts t. The base carries a platen 'or accommodating the workpieces and a cross-head 5 is arranged to move vertically toward and away from the platen 5, being guided by slides 1 on the posts t. .The head 3 is bored to provide a cylinder 8 arranged Ain the vertical center line of the press. A piston in the cylinder is secured to the cross-head 6. Lifting cylinders 9 and i0 are disposed at the ends of the press and have pistons il therein bearing on shoulders i.

i2 on the cross-head t. The cylinders 9 and i0 serve to return the cross-head after a working stroke eected by the cylinder 8.

The cylinders 9 and iii are connected t0 a pipe il leading from a control station indicated generally at S in Figure l and hereinafter described in detail. A pipe i8 connects the cylinder 8 to the control station S.

The control station is shown in diagram in Figure 4. In this diagram the valves have been indicated conventionally, but it will be understood that at the pressures which may be ernployed and with the volumeof water to be controlled, it will generally be necessary to use power-actuated valves withmanual controls for the valve-actuating mechanism. The pipe il, which supplies the cylinders t and iii, is connected through a 3-way valve 2i to a supply pipe 22. Ordinarily theA valve 2i remains open and water is supplied to the pipe 22 under constant pressure so that the cylinders t and ill constantly urge the cross-head .6 of the press upwardly.

The valve 2| may be shifted to connect the pipe il to the supply pipe 22 or toa discharge pipe 23, as desired.

The pipe i8 is connected to a T 26. The T 2S connects the pipe i8, through a valve 2l, to. a supply pipe 28. The T 26 also connects the pipe it, through a valve 29, to a discharge pipe 30. Ii? the valve 29 is closed and the valve 2l opened, luid under pressure passes to the T 26 and thence to the main press cylinder 8, overcoming theforce of the lifting cylinders 9 and it, and eiiecting a working stroke of the press. f

the pump.

ment of the cross-head to effect automatic stroking.

The water for 'the cylinders s, s, 'and 1u is taken from a prelller tank 91 operatingunder a low head, say, 40 to 1004 pounds per ,square inch. tank has an air space above the water level so as to accommodate the varying quantitiesy of Water which are supplied to it in operation./ Make-up` waterv is supplied to the tank 4under pressure through a valved supply pipe 98, but in general the system is a circulatory one, the water being discharged from the cylinders back to the preller through the pipes 23 and 80. A pump v'99 supplies waterfrom a sump 40 to the preilller through a pipe 39a.

Water fromI the preflller 91 'passes through a pipe, 4i to a cooler 42 consisting of 4a pipecoil having a water vjacket provided with pipes 43,

whereby cooling water may be circulated through the-jacket. The water passes from the cooler 42 through a pipe 45 vterminatingin the inlet 45 of acentrifugal pump 41. The outlet of theY rpump `41 is connected through a pipe 48 to the attempted to circulate it through the pump and 'letting -the pump idle. Indeed, in manycases, it may not be feasible to circulate water through the idle .pump at all. v A

Figure 5 shows the characteristics of the pumps above described. It will be noted therefrom that the pumps deliver maximum head at zero capacity and that only a'. slight drop/in pressure,occurs when delivering at full rated volume. By way of example, the pumps 41, 49, and 5I deliver maximum heads of approximately 1250, 1250, and 2000 pounds per square inch, re-

vspectively, so that by using pumps 41 and 49 in series, a working pressure of 2500 pounds per square inch is obtained and by using all three pumps in series a wo king. pressure of 4500 Y pounds per square inch is obtained. Whatever inlet of a Icentrifugal pump 49. Y The outlet of;

the pump 49 is, in turn, -connected through a pipe 50 to the inlet of a centrifugal pump 5|. Its

outlet is connected through a pipe 52 and a check working pressure is used, the cylinder 8 easily overcomes the cylinders 9 and I0 because the total cross sectional area of the former is very much greater than the sum of those of the latter. The valve 2|, however, may be shifted to its second position to connect the pipe I1 to the pipe 23. The cylinder 8 then has to overcome only the preflller pressure in the cylinder 9 and I0, instead of the main working pressure, therev alve 53 to the pipe 28 leading to the control' station S. A branch pipe 54 leads from the'check valve 53 to a pair of accumulator-bottles 55 providing an air cushion for the system. An-

air compressor 58 is provided for supplying air as required to these bottles through a connecting pipe-(not shown).

The pumps 41, 49, and 5I are each independently driven by motors 51, 58, and 59, respectively, and these motors are .separately controlled by switches 80, 8i, and 62, respectively, at the control station S. It will be noted that the pumps arearranged in series so that by actuating one, ,two or three of them, as may be desired, three stages of pressures hay beobtained, for example, .stages of 1250, 2500 and 4500 pounds per squareiinch. y

The pumps employed are of the'multi-stage l centrifugal type. In order to minimize the prespumps are operating. Thus the speed o'f the press sure drop in the system, I provide for bypassingv any idle pump or pumps through mechanism shown in detail in Figure 3.

Referring to Figure 3, the :pump casing is -indicated at 83. It is surmounted by a check valve body 84 having a vertical bore 85 which-registers with the inlet 86 of the pump. The inlet 48 communicates withthis bore. At its upper end the boreleads to a horizontal bore 81, but communication between the two is shut olf when the pump is running by a check valve 88. Water entering the inlet 48, therefore, passes downwardly through the bore 55 into the inlet 88 of The pump` discharges the water at materially higher pressurethrough the discharge port 89 into a vertical bore 10 in the valve'body 54. 'I'he bore 18 communicates with the horizontal bore 81. Water discharged from the pump is,l as stated, at a materially higher pressure than thewater entering through the inlet `48 and the check'valve 88 is therefore held closed. The water-is finally discharged from the pump through an outlet 12 communicating` with -the pipe 48, 50 6112, as the case may be. f

In case a pump is standing idle, water entering through its inlet raises the valve 58 and passes through the horizontal bore 81 directly tothe outlet 12,1thus saving the material loss of head which would beencountered ii it were head is substantially pressure employed.

Numerous advantages are obtained by my inthe same regardless of the vention. One of the primary ones is simplicity of control. Another is the speed with which the head can be moved from its top position'into engagementwith the work. This is due to the fact that the pumps are delivering maximum pressure with the valve 21 closed, and that substantially maximum pressure is immediately imparted to the working cylinders when the .Valve is opened. This gives speedy idling and rapid stroking during the working of the press. A further advantage is that my improved press'has greater flexif bility o f operation and that as soon as the workers' vbecome skilled in its -use they can accomplish far vmore with it than with ordinary presses.

I have illustrated 4and described a present pre ferred embodiment of the invention. It will be understood, however, that this is by way of illustration only and that it may be otherwise emboiieldiithin the Ascope Aoi" the following claims.

1. A hydraulic press comprising a m'ovable press Y head, a pressure cylinder having a plunger therein connected to the press head, a water supply pipe leading tothe cylinder, a plurality of` centrifugal pumps having the characteristic of delivering substantially lmaximum head at zero capacity, the pumps being connected in series to the supply pipe, motors for individually driving the several pumps, separate controls' for each motor-whereby a pump may be controlled at /will independently of the control of any other pump and the line pressure thereby varied, a by-'pass around at least one pump having a check-valve therein landV a shut-off valve in the supply pipe between the cylinder and the pumps. 4

A hydraulic press comprising a movable Y A'controlled at will independently of the control of any other pump and the line pressure thereby vvaried, a by-pass around atleast oneof the press head, a pressure cylinder having a plunger therein connected to the press head, a water supply pipe leading to the cylinder, a plurality of multi-stage centrifugal pumps .having the characteristic' of delivering substantially maxi- .mum head at zero capacity. the pumps being connected in series to the supply pipe, motors for individually driving the several pumps. separate controls for each motor whereby a pump may be pumps having a check-valve therein movable to closed position when the pump with which 'the by-pass is associated is in operation but movable to open position when not subject to the pressure generated by said pump, whereby the by-pass

Images