US2058377A - Hydraulic press control - Google Patents

Description

Oct. 20, 1936.

H. G. FRANCIS v HYDRAULIC PRESS CONTROL Filed May '7, 1931 awww Patented Oct. 20, 1936 vPATENT OFFICE HYDRAULIC: Pmiss CONTROL Harry G. Francis, Bushville, Ind., assigner to` Chas. E. Francis Co., Bushville,

ration of Indiana Ind., a corpo- Application May 7, 1931,.Serial Noa-535,645 3 Claims. (Cl. 60-54-5) tively rapid movement of the press-platen at lowv pressure and relatively slow movement Vat high pressure, to provide means for automatically changing from low-pressure high-speed movement of the platen to high-pressure low-speed thereof, and to provide means for automatically stopping the operation of the pressure creating means when the work being pressed has been subjected to a predetermined maximum pressure.

In carrying out my invention, I employ a press provided with a platen operatively connected to a piston in the cylinder. Associated with this press I provide-a pressure intensifier, and as a source of pressure for both the intensier and the press I employ a rotary pump. 'I'he rotary pump is connected to the press cylinder and to theintensier through an automatic valve which operates to direct the liquid supplied by the pump from the press cylinder to the intensiiier at the proper time. In addition, I provide means for automatically interrupting the operation of the pump when the pressure exerted on the work in the press reaches a predetermined maximum.

The accompanying drawing illustrates my in -in the drawing has a head I0 and a movable platen I I, between which and the head the work to be pressed is placed. As illustrated, the head `II) is disposed above the -platen and the work is placed upon the platen and elevated into engagement with the head by upward movement of the The platen II is shown as being mounted upon the upper end of a piston I2 which is vertically slidable in the press-cylinder I3, so thatthe platen can be raised by supplying liquid under lpressure tothe press-cylinder.

As previously indicated, I associate with the press a pressure intensien Conveniently, although not necessarily, the intensifier is arranged in direct association with the press-cylinder I3 in order to conserve space. To this end, the intensiiierl embodies a cylinder I4 which is mounted below. and in alinement with the press cylinder I3. Axially slidable in the cylinder I4 is a piston I5 with whichv there is movable a cylin- 5' drical rod I6 of smaller cross-sectional area. The rod IB projects through suitable packing into the lower end oif the cylinder I3, as is clear from Fig.

1. Preferably, in order to conserve space vertit cally, the piston I2 is provided with a downwardly 1 0 opening central recessl I1 into which :the rod Il may move, the recess I1 being of larger diameter than the rod in order to avoid any contact between the rod I6 and the piston I2.

From the construction described itwill be apl5 parent that -by supplying iluid under pressure to f the cylinder I4 below the piston I5 an increased pressure can be built up in the press cylinder I3, the ratio of the pressure in the cylinder I3 to that of the cylinder I4 being equal to the ratio between 20 the cross-sectional area of the intensier piston I5 and the rod I5. I

Forthe purpose of supplying liquid under pressure to the press and intensiiler cylinders I3 and I4, I employ a pump 20 which is preferablyof the 25 rotary type in order to supply liquid to the press andv intensifier cylinders at a substantially constant rate. The liquid discharged from the pump 20 is conducted through a pipe 2| past a check valve 22 to a valve chamber 23 in the casing 24 o f ,an automatic valve. From the valve chamber 23, a pipe 25 leads past a check valve 26 to the press cylinder I3.

Thel intensifier cylinder I4 is 'connected to the valve casing 24 through apipe 21. 'I'he valve casing 24 is provided interiorly with a passage '2l affording communication between the valve chamber 23 and the pipe 21, liquid flow through this passage being controlled by a suitable valve 29. In Fig. 2, the valve 29 is shown in its lower or closed position in which it prevents communication between the valve chamber and the pipe 21..

Automatic means, responsive to duid-pressure, is employed for controlling movements of the valve 29. To this end, a cylinder 3| is formed in the lower part of the valve casing '424,` and a piston 32, slidable in such cylinder, is connected as by `a. stem 33 t'o the valve 29 for joint movement therewith, this connection being shown as a thrust- 50 transmitting connection preferably having a slight amount of lost-motion. A spring 34 acting between the piston -32 and a suitable' abut-- vment within the valve casing 24 serves normally to hold the piston '.tthe limit of its downward 55 movement or in the position shown in Fig. 2, with a shoulder 32' on the piston in contact withand co-operating with a shoulder 24' in the valve casing. A spring 35, which acts between the valve 29 and a stationary abutment, serves normally to hold the valve 29 closed.

The cylinder 3| is connected through a pipe 31 with the pipe 25 at a point between the press cylinder I3 and the check valve 26, in order that liquid within the valve cylinder 3l may be subjected to the same pressure as that which exists in the press cylinder I3. 'I'he piston 32 is made of somewhat larger cross-sectional area than the valve 29.

If the pump is placed in operation with the parts of the device in the positions indicated in Figs. 1 and 2, the'liquid discharged from the pump 26 will flow through the pipe 2|, valve chamber 23, and pipe to the press cylinder I3 to raise the piston I2 and platen II. As the valve 29 is closed there will be no liquidsupplie'd to the intensifier cylinder I4. Because of the pipe 31, which interconnects the pipe 25 and valve cylinder 3I, substantially equal unit-pressures will exist in the cylinder 3| and in'the valve chamber 23. The former pressure acts upwardly on the piston 32 and the latter pressure acts downwardly on the valve 29; and as the eiective cross-sectional area of the piston 32 is greater than that of the 3 valve 29, a tendency for the valve 29 and piston 32 to move upwardly is created. The springs 34- and 35 are made of suiilcient strength to counteract this tendency toward upward movement of the valve 29 and piston 32 until the work on the platen II engages the head II). When this occurs, pressure builds up in the pipes 2| and 25, in the valve chamber 23, and in the cylinder 3|. Eventually, this pressure willreach such a value that the tendency of the piston 32 and valve 29 to move upwardly will overcome the downward force exerted jointly by the springs 34 and 35, and the piston and valve will then move upwardly to open the valve and to provide communication between the valve chamber 23 and the pipe 21. Thereafter, the liquid discharged from the pump 20 will flow through the pipe 2| to the valve casing 23, and through the valve casing 24 and pipe 21 to the intensifier cylinder I4. The liquid thus discharged into the intensier cylinder will move the piston I5 therein upwardly to cause the rod I6 to build up an increased pressure in thepress cylinder I3 as above set forth.

When the desired pressure is reached within the press cylinder I3, the pump 20 is stopped; and after the work in the press has been subjected to pressure for the desired length of time, the liquid in the cylinders I3 and I4 is removed to permit the platen II to descend under the in iluence of gravity. l

For the purpose of controlling thisrelease of pressure, liquid discharge pipes 40 and 4I may be provided. The pipe 40comm1micates with the press cylinder I3, desirably by being connected to the pipe 25 at apoint between the press cylinder and the check valve '26, while the pipe 4I -communicates with the intensifier cylinder I4 as by being connected to an intermediate point of the pipe 21. Both pipes 40 and 4I discharge into a liquid-supply tank `42 from which liquid is supplied to the pump 20 through a supply pipe 43. 'Ihe two pipes 40 and 4I are respectively provided with valves 44 and 45 which are closed during the pressing operation but which may be opened to release the pressure in the press and intensifier cylinders I3 and I4 to permit the liquid therein to be discharged into the supply tank 42.

Preferably, -the pump 20 is controlled by suitable manual and automatic devices such as those `illustrated in Fig. l, which contemplate that the pump 20 will be driven by a three-phase electric motor 41. Supply current from line' wires 43 to the motor 41 is under the control of a magnetic switch 49 biased toward"open position as by a spring 50 and adapted to be closed by the energization of a solenoid 5I. As shown in the drawing, one end of the winding of the solenoid 5| is connected to one of the 'line wires 48 while the other end is connected to another of such line wires through suitable manually controlled switches 52 and 53 and through two automatical ly operable switches 54 and 55.

Theswitches 52 and 53 comprise a form of push-button control commonly used in association with electrically operated devices. The switch 52 is normally open and has associated with it a holding circuit embodying a switch 56 which'isadapted to be closed when themotor control switch 49 is closed. The manual switch 53 and automatic switches 54 and 55 are normally closed; so that when the manual switch 52 is momentarily closed a circuit is completed through the solenoid 5I, the resultant energization oi the solenoid closing the motor control switch 49 and the switch 56 of the holding circuit. Because, of the presence oi the holding circuit embodying the switch .56, only momentary closing of the switch 52 is necessary to cause operation of the motor 441 and pump 2|). If the circuit of the solenoid 5I is interrupted as by opening' of any of the switches 53, 54, and 55, the spring 53 will operate to open the motor control switch 49 as well as the holding circuit switch 56 to stop the operation of the motor 41 and ,pump 20.

The automatic switch 54 is shown in the drawing as being a limit switch adapted to prevent the platen II from striking the head II) of the press if an attempt should be made to close the press without any work on the platen. To this end, the platen is provided with an abutment 58 which is movable with the platen and which is adapted to engage the switch 54 if the platen approaches too closely to the head I0.

As shown in the drawing, the switch 55 is a normally closed switch adapted to be opened by the energization of an associated electro-magnet 59. For the purpose ot controlling energization oi the electro-magnet 59, I provide a pressureresponsive switch 60 responsive to pressures in the press cylinder I3. Conveniently, the switch 60 embodies an indicating hand 6I which is mo'vable across a suitable scale 62 to indicate the pressure existing in the press cylinder I3. The

switch also embodies a movable member 63 which can be adjusted to be engaged by the hand 6I at any desired pressure. rPhe member 63 will be set at the pressure corresponding to the maximum pressure which is to be created in the press cylinder I3, and when this pressure is obtained in the press cylinder, the switch 60 will be closed to .energize the magnet 59, open the switch 55, and d e-energize the solenoid 5| to interrupt the supply of current to the motor 41.

Preferably, the pressure release valve 45 in the pipe 4I is automatically controlled. To this end, it may be connected to a piston 65 in a cylinder 56, the cylinder 66 being connected to the pipe 2| in order that the piston 65 may be responsive to pressures therein. 'I'he valve 45 is biased toward open position and is adapted to be closed by pressure in the pipe 2|. When the device is at rest, the valve 45 is open, but when suiilcient liquid has been supplied to the press cylinder I3 to bring the work on the platen II into engagement with the head I0, pressure -will be built up in the pipe 2| and will close the valve 45 before the valve 29 is opened to supply liquid to the intensifier. A

As shown in the drawing, the work to be pressed is indicated as in place on the platen, and the parts of the device are shown in the positions they occupy when the press is not being operated. To operate the press, it is necessary only to close momentarily the switch 52. As above indicated, the momentary closing of the switch 52 will close the motor control switch 49 to start the motor and pump 20. The pump 20 draws liquid from the supply tank 42 through the pipe 43 and discharges it as above set forth to the press cylinder I3. When the work on the platen engages the press-head I0, pressure builds up in the pipe 2|,` and eventually reaches a value suiiicient to close the valve 45. At a somewhat higher pressure, the valve 29 is opened and liquid is supplied to the intensier cylinder I4 to build up an increased pressure in the press cylinder.

When this press-cylinder pressure reaches a desired maximum, the pressure-responsive switch 60 is closed to energize the electro-magnet 59 and open the switch 55, thus de-energizing the solenoid 5| and interrupting the supply of current to the motor 41|, with the result that the supply of liquid to the press ceases. When the work has been subjected to the pressure for the desired length of time, the valve 44 is opened, thus permitting the platen and work to descend under the iniiuence'of gravity -and to force the liquid in the press cylinder I3 through the pipe 40 to the tank 42. As the pressure in the press cylinder decreases, the valve 29 will be closed to return it to the position illustrated in Fig. 2, and the valve 45 will somewhat subsequently be opened to permit liquid to flow from the intensier cylinder I4 to the storage tank 42.

I claim as my invention:

1. In combination, a press-cylinder, an intensier associated therewith, a source of uid under pressure, a press-cylinder supply pipe connecting said source with said press-cylinder, an intensifier supply pipe, a normallyclosed valve openable to connect said two supply -pipes` toinder side of said check-valve, alvalve in said press-cylinder discharge pipe, a discharge pipe for said intensifier connected thereto on the intensier side of said iirst mentioned valve, a'

valve in said intensifier discharge pipe, and means in addition to`said rst mentioned valve for stopping the supply of'iiuid to said intensifier.

2. The invention set forth in claim 1 with the addition of pressure-responsive means for opening the valve in the intensifier discharge pipe when press-cylinderfpressure is below a predetermined value and'for closing the valve in the intensifier discharge pipe when thepress-cylinder pressure is above such predetermined value.

3. 1n a fluid-pressure press having relatively movable heads, a. press-cylinder, a pressure intensifier associated therewith, a, pump with pipe lines and connections arranged to supply fluid from said pump to said press-cylinder and intensiier, means in said pipe lines for prewanting return flow of fluid from said press-cylinder and intensifier to said pump, valve means for directing iiuid from said pump either to said presscylinder or to said intensifier, means vresponsive to pressure in said press-cylinder for operating said valve means to direct uid from said pump to saictintensifler, a release valve for controlling release of iiuid from said press-cylinder and intensifier, an electric motor for driving said pump, a main switch for controlling the supply of current to said motor, a` holding switch, said main switch and holding switch being biased toward op'e'n position, electro-magnetic means for maintaining said main switch and holding switch closed, a normally closed auxiliary switch connected in series with said holding-switch and electro-magnetic means, and adjustable means operative upon the occurrence of a predetermined maximum pressure on work between said heads for opening said auxiliary switch.

HARRY G. FRANCIS.

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