US2681620A - Pump and tank arrangement for presses - Google Patents

Description

June 22, 1954 w ERNST 2,681,620

PUMP AND TANK ARRANGEMENT FOR PRESSES Original Filed Sept. 15, 1949 3 Sheets-Sheet l 0 FIG I INVENTOR BY WALTER ERNST mmzmjwm'n ATTORNEYS June 22, 1954 w. ERNST 2,681,620

PUMP AND TANK ARRANGEMENT FOR PRESSES Original Filed Sept. 15. 1949 5 Sheets-Sheet 2 58 FIG 2 INVENTOR WALTER ERNST June 22, 1954 w. ERNST PUMP AND TANK ARRANGEMENT FOR ERESSES Original Filed Sept. 15, 1949 FIG 3 85 INVENTOR 3 Sheets-Sheet 3 WALTER ERNST AIIORNEYS Patented June 22, 1954 PUMP AND TANK ARRANGEMENT FOR PRESSES Walter Ernst, Dayton, Ohio, assignor to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Original application September 15, 1949, Serial No. 115,901. Divided and this application November 20, 1950, Serial No. 196,620

4 Claims.

This invention relates to hydraulic presses, and particularly to hydraulic presses of the self-contained type and to a novel tank and pump arrangement therefor.

In the usual type of self-contained hydraulic press, the pump and motor therefor and the fluid reservoir for the hydraulic fluid employed are mounted on the head of the press, this arrangement being convenient because of the economy of space and because the shortest pipes are needed 1 to connect the pump with the power unit of the press.

In modern high speed presses there is a rapid movement of hydraulic fluid from the reservoir to the pump and from the pump to the power unit of the press. When this movement of oil from the reservoir to the pump becomes too rapid, there occurs what is known as cavitation, which means that there are voids in the oilsupply created by too great a difierential between the pressure on the oil in the reservoirand the pressure at the suction side of the pump. Cavitation is undesirable because it reduces the speed of operation of the press, makes the operation of the pump inefiicient, and creates noise and vibration.

The instant application is a division of my application Serial Number 115,901, filed September 15, 1949, and assigned to the same assignee as the present application.

With the foregoing in mind, one of the primary objects of this invention is the provision of a pump and tank arrangement for a hydraulic power unit such that the supply of fluid is supercharged, whereby substantially all cavitation in the oil supply to the pump is eliminated.

Most hydraulic power units utilize an oil as the hydraulic medium which has good lubricating properties, and this oil is employed for lubricating the pump and the moving parts of the hydraulic unit. Ordinarily, the hydraulic medium is the sole source of lubricant for the pump, and an interruption of the supply of oil to the pump during operation thereof could lead to serious damage to the pumping mechanism.

It is accordingly a still further object of this invention to provide an arrangement whereby operation of the pump of a hydraulic power unit is prevented, unless there is an adequate supply of oil in the supply reservoir for the pump.

In a hydraulic system of the type described, the oil continuously circulates during operation of the press from the reservoir to the pump and then to the power unit, and then back through the pump to the reservoir or directly from the power unit to the reservoir. In any case, there is opportunity for the oil to become somewhat contaminated during operation of the press, and the contaminating material has a tendency to settle out in the reservoir where the movement of the oil is slightest.

It is accordingly a still further object of this invention to provide an arrangement for a hydraulic unit including a reservoir for the hydraulic medium wherein the said reservoir can readily be cleaned at any time, and without the necessity of removing all of the hydraulic medium from the hydraulic system of the unit.

These and other objects and advantages will become more apparent upon reference to the following description taken in connection with the accompanying drawings, in which:

Figure l is a side view of the upper end of a hydraulic press embodying the teachings of this invention with a portion of the sheet metal cover on one side of the head of the press removed;

Figure 2 is a vertical section taken through the upper part of the press, and is indicated substantially by the line 22 on Figure 1;

Figure 3 is a vertical section indicated substantially by line 3-3 on Figure 1, showing somewhat more in detail the tank and reservoir arrangment according to this invention;

Figure 4 is a vertical section taken on line 4-4 on Figure 3, showing the valved connection between the reservoir on top of the press head and the pump supply tank mounted on the back of the press head; and

Figure 5 is a diagrammatic showing of the elec tric control circuit by means of which the motor for driving the pump is interlocked with the valve of the valve connection of Figure 4.

Referring to the drawings somewhat; more in detail, the press shown therein comprises a head In supported on the spaced uprights l2 and I l and interconnected with the press bed (not shown) by the strain rods I6.

Mounted in head m is a cylinder is within which is reciprocably mounted the double acting press ram 2|] connected at its lower end with press platen 22 that is slidably guided on uprights i2 and M by the usual gib arrangement. Ram 2% may be hollow, as at 2:1, to receive a booster ram 26 of substantially conventional construction, and which is mounted in the closed upper end of cylinder I8.

The fluid supply to the upper end of cylinder ill for both the booster ram and the main press ram is by the conduit 28 in the press head, while the supply of fluid to the lower end of cylconducted thereto.

inder I8 is by conduit 3!]. The upper end of cylinder i8 also comprises a plurality of surge valves, one of which is illustrated at 32, and which supply fluid to the booster ram and to the upper end of cylinder [8 during the rapid advance of the press ram and platen. These surge valves are adapted for opening by suction or may be piloted open by fluid conducted through from the lower end of cylinder i8, as by the pilot conduits 34.

The upper end of cylinder is projects into a reservoir space formed on the top of the press head by the circumferential wall part 36 and cover plate 38. This reservoir space is suitably sealed against the press head either by being welded thereto or by suitable gasket means, as is wellknown in the art.

The conduits 28 and Bil lead to the connector flanges ii) and 52 on the side of the press head, which also have connected thereto the conduits M and &6 leading to the opposite sides of the main hydraulic pump Pump 5!] is preferably a reversible variable delivery pump having suitable control means according to well-known practrees, by means of which its delivery can be varied and reversed.

Pump all has drive pulley means 52 over which pass drive belts as that also pass over pulley means 55 mounted on the output shaft or" drive motor 58 that is supported on cover 38 on the reservoir on the press head. The belt drive arrangement for pump 59 has certain advantages that motor 58 can be the usual fairly high speed electric motor, and the pulleys 52 and 55 so selected that the pump 56 can operate at its proper speed which is usually much lower than the normal operating speed of a standard motor. Also, for locations where odd frequencies of power are availabie, a standard motor for that frequency can be employed and the proper speed of operation for pump 5% be obtained.

In Figure 1, it will be observed'that pump 50 is mounted on top of a tank arrangement 59 that is secured to the back of the press head, as by the stud and nut arrangement indicated at 60. Figure 3 will reveal that the tank 59 is divided into compartments by an intermediate partition 62 and that pump 59 is positioned over the lefthand compartment and is adapted for drawing fiuid therefrom by means of the down pipe 64.

Inasmuch as pump 56 is reversible, there is included in its suction line a shuttle valve or some other well-known instrumentality for closing 05 the one side of the pump from the other. This may be arranged within the pump tank compartment, and a suction line lead therefrom to each side of the pump, or the shuttle valve may be, as illustrated, embodied in the pump self, and a straight suction line, as at 64, lead into the tank.

For the purpose of cleaning the pump compartment, there is provided a removable cover plate 66 secured over aperture 58 in the bottom of the pump compartment by screws iii.

The right-hand compartment of the tank communicates with the pump compartment through a valved connection 52 that is normally open, but which is adapted for being closed by the operating stem and knob '14. The right-hand compartment is normally under atmospheric pressure and serves to receive all slippage from all parts of the hydraulic system of the press that is Usually there are a number of slippage lines about a press, but there is only illustrated in the drawings a slippage line leading from pump 50. This line is identified by reference numeral I6 and maintains the pump housing drained of slippage fluid.

A pump I8 is mounted on the side of the righthand compartment, and has its suction side opening into the compartment and its discharge side connected by conduit 82 with the reservoir on top of the press head. A motor 34 may be mounted integrally with pump 18 in either continuous or intermittent operation.

As will be seen in Figures 3 and 4, there is a conduit 86 mounted in the press head which connects the reservoir with the pump compartment of tank 59. This conduit has a valve 88 therein with a stem 90 leading through cover plate 38 to an operating knob 92. The valve is normally open to provide free communication between the reservoir and pump compartment, and in this manner the fluid in the pump compartment is always under greater than atmospheric pressure. This supercharged condition of the fluid in the pump compartment greatly minimizes the amount of cavitation occurring in the suction line leading to the pump, and thus permits more efficient, more rapid, and quieter operation of the pump and the press.

The valve 88 is adapted for being closed to interrupt communication between the reservoir and the pump compartment when it is desired to clean the said compartment. When the valve 88 is so closed, and the pump '58 is operated by energizing motor 34 through switch 35, substantially all of the fluid in the pump compartment will be moved into the right-hand compartment of tank 59, whereupon valve 12 may be closed and motor 84 de-energized and, thereafter, the cover 66 removed for the cleaning of the pump compartment.

In order to prevent operation of main pump 59 during the time when its compartment is not adequately supplied with fluid, stem SE of valve 88 may include a member 94 adapted for engaging and actuating a limit switch LS3 when the valve is closed.

LSi is connected in circuit with drive motor 58 in the manner illustrated in Figure 5. In Figure 5 it will be noted that LS! is in series between power lines Li and L2 with solenoid 95 and normally open start switch 98. Solenoid 96 is associated with armature Hit of a contactor having a normally open holding blade Hi2 and a normally open motor energizing blade I04.

Blade )2 is in series with normally closed stop switch I06, and this branch is connected in parallel with start switch 98. Switch blade HM is in series with motor m8 and the arrangement is such that any time switch 98 is closed when switch LS5 is closed, motor 58 will be energized and will remain energized until switch 166 is opened, or whenever switch LS! is opened by closing of valve 88.

From the foregoing, it will be seen that I have devised a novel reservoir and tank arrangement for a hydraulic press or similar hydraulic apparatus, characterized in that the pump tank is always superoharged and under a predetermined head; in which the pump compartment can readily be cleaned without removing all of the hydraulic fluid from the system; and wherein driving of the pump is prevented whenever there is an insuflicient supply of fluid to the pump compartment.

It will be understood that this invention is susceptibleto modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a hydraulic press having a press frame with a head, a fluid reservoir on top of said head, a fluid tank mounted on the back of said head below said reservoir, said tank being closed, a conduit comprising a valve connecting said reservoir and tank whereby said tank is maintained under a predetermined head, said valve having an operating member movable between valve open and valve closed positions, a pump hydraulically connected to draw fluid from said tank, an electric drive motor connected to drive said pump, a normally closed switch in the energizing circuit for said motor, and means associated with said operating member operable for opening said switch when said member is moved to its valve closed position, thereby to prevent operation of said motor and pump when the reservoir and tank are disconnected.

2. In a hydraulic press having a frame with a press head; a fluid reservoir on top of the head, a closed fluid tank mounted on the back of the head below the reservoir, a conduit including a valve connecting said reservoir and tank, a pump hydraulically connected to draw fluid from said tank, an electric drive motor for said pump, a normally closed switch in the energizing circuit for said motor, a valve stem on said valve for the opening and closing thereof, and a switch actuator mounted on said stem and positioned to engage and open said switch when said valve is closed, thereby to prevent operation of said motor and pump when the reservoir and tank are disconnected.

3. In a hydraulic press; a fluid reservoir, a closed fluid tank below said reservoir, a valve connecting said reservoir and tank, an operating member for the valve having valve open and valve closed positions, a pump hydraulically connected to draw fluid from said tank, a drive motor connected to drive said pump, an energizing circuit for saidmotor, a switch adapted to interrupt said circuit when actuated, and means associated with said operating member operable to cause actuation of said switch when said member is moved to its valve closed position, thereby to prevent energization of said drive motor when the fluid connection of the reservoir to the tank 'is closed.

4. In a hydraulic system, a pump tank, a source of fluid supply for the tank, a fluid flow connection between said tank and said source of fluid supply having a valve for closing the connection, a pump having its suction line extending into the said tank, a drive motor for driving the pump, an energizing circuit for the motor, a switch connected into the said circuit normally permitting energization of said motor, but having an actuated position where energization of the motor is prevented, an operating member for said valve having valve open and valve closed positions, and means on said operating member for engaging said switch when the said member is moved to valve closed position to actuate said switch into the said position to prevent energization of said motor and, therefore, operation of said pump when the fluid supply from said source to the tank is interrupted.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,175,170 Mulligan Mar. 14, 1916 1,346,898 Kingsbury July 20, 1920 1,566,591 Goldsmith et al Dec. 22, 1925 1,907,208 Lebel May 2, 1933 1,960,389 McF'erran, Jr May 29, 1934 2,102,140 Ungar Dec. 14, 1937

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