US3081659A

US3081659A - Hydraulic system providing successive application of force to shear means

Info

Publication number: US3081659A
Authority: US
Inventors: Theobald Walter
Original assignee: Siemag Siegener Maschinenbau GmbH
Current assignee: Siemag Siegener Maschinenbau GmbH
Priority date: 1958-11-24
Filing date: 1958-11-24
Publication date: 1963-03-19
Anticipated expiration: 1980-03-19

Description

March 19, 1963 w. THEOBALD HYDRAULIC SYSTEM PROVIDING SUCCESSIVE APPLICATION OF FORCE TO SHEAR MEANS Filed Nov. 24, 1958 United States Patent HYDRAULIC SYSTEM PROVIDING SUCCESSIVE APPLICATION OF FORCE T0 SHEAR MEAIQS Walter Theobald, Siegen, Westphalia, Germany, assignor to Firma Siernag Siegener Maschinenbau G.m.b.H.,

Dahlbruch, Westphalia, Germany Filed Nov. 24, 1958, Ser. No. 775,939 9 Claims. (Cl. 83-554) The invention relates to power shears, and more particularly to an arrangement for actuating movement of shearing blades in such shears.

It is a primary object of the invention to utilize to the fullest measure available hydraulic pump capacity in such power shears for driving the operating piston actuating the shearing or operating movement of the blades.

Another object of the invention is the provision of an automatic arrangement for operatively connecting all the pumps in such hydraulically operated power shears to the operating piston.

Yet another object is the provision of controls for such an automatic arrangement which are sensitive to the position of the blades and which initiate changes in the connections between the pumps and the operating piston in response to the position of the blades themselves.

A further object of the invention is to utilize pressure changes occurring in the hydraulic system of the power shears due to the position of the blades to actuate such controls.

An additional object of the invention is the provision of fully automatic controls for such power shears which cause the shears to perform all necessary movements without further manipulative steps of the operator once a work piece has been located between the blades of the shears and movement of the machine has been initiated.

Finally, it is an object of the invention to provide such an automatic arrangement which is relatively simple and rugged in its structure, and therefore relatively inexpensive in first cost, reliable in its operation, and not requiring expensive maintenance.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a somewhat schematic elevational view, partly in section, of the shearing arrangement of the invention.

Referring now to the drawing, there is shown a lower blade 1 fixedly connected to the operating cylinder 3 by means of connecting members 2. The upper blade 4 is actuated by the operating piston 5 which is reciprocably supported in operating cylinder 3. The lower blade 1 is furthermore rigidly connected to a pair of positioning pistons 6 reciproca'bly slidable in positioning cylinders 7.

The upper blade 4 is positioned and held in position preparatory to the shearing operation by opposite pairs of positioning pistons 8 and which are reciprocably movable in respective cylinders 9 and 11.

Hydraulic fluid under pressure is supplied to cylinders 9 by a pump which is driven by motor 16. The bydraulic fluid line connecting pump 15 to cylinders 9 passes through an automatic three-position valve 14 and a check valve 12 which is equipped with a throttling bypass 13. Pump 15 may also be connected by valve 14 to cylinders ice 11 so as to actuate positioning pistons 10. A remotely controlled two-position valve 17 is interposed in the hydraulic line connecting valve 14- and cylinders 11.

The positioning cylinders 7 for the lower blade 1 are supplied with hydraulic fluid under pressure from a pump 15 actuated by a motor 16', the flow of the fluid being controlled by a remotely controlled two-position valve 18 interposed between pump 15' and cylinders 7.

Hydraulic pressure for actuating movement of operating piston 5 is generated by a battery of hydraulic pumps 25 to 30 which are driven by individual motors 19 to 24 and the discharge lines of which are connected by remote control valves 31 to 36 to a common pressure manifold 136 which communicates with the larger one of the cylinder spaces of a differential cylinder 38 in which a dilferential piston having a portion 37 of larger cross-sectiona1 area and a portion '39 of smaller cross-sectional area is reciprocably movable.

Oil is pumped under pressure into the cylinder space under difierential piston portion 37 and causes higher pressure to be exerted by smaller piston portion 39 on water contained in the cylinder space 44 above the smaller differential piston portion 39. The water in space 44 is thus capable of transmitting pressure of the order of several thousand pounds per square inch, such as may be required for shearing heavy rolled metal plates, to the operating piston.

The pressure water line 40 which connects cylinder space 44 with operating cylinder 3 is also connected through a check valve 42 with a low-pressure water tank 41. The necessary pressure for driving water from tank 41 into Water line 40 when the latter is under very low pressure may be provided by either arranging the tank 41 on a level higher than that of the other elements of the water circuit, or by connecting the space above water level of the tank and enclosed by the tank walls to a source of compressed air under suitable pressure.

A normally closed valve 43 is opened by the diflerential piston 37-39 on its return stroke, either by direct mechanical engagement with a control element fastened to the piston for joint movement or by an interposed control means including a limit switch actuated by the piston and energizing a solenoid which in turn operates valve 43 in a Well known manner. Valve 43 when open con nects tank 41 below the water line with cylinders 3 and 44.

A pump 45 is connected with tank 41 to replenish any water leakage in the pressure water system by water drawn from a storage container when the water in tank 41 drops below a predetermined level. A float switch or similar known device starts and stops the electric motor driving pump 45.

Pumps

15, 15 and 25 to 30 draw oil from a common sump 46 and the

valves

14, 18 and 31 to 36 are arranged to return the outputs of the respective pumps in the inoperative position.

The manifold 136 communicates through a remote control valve 47 with valve 13 and also with cylinder 7, and is also connected to one of the outlets of two-way valve 17.

The afore-described device operates as follows:

In the inoperative condition of the power shears illustrated,

valves

14, 18 and 31 to 36 are so positioned as Patented Mar. 19, 1963 3 to return oil from

pumps

15, 15 and 25 to 30 into the sump 46. I

Operation of the shears is initiated by shifting valve 18 into a position connecting pump 15' to cylinders '7 whereby the lower blade 1 is raised from the inoperative position to a preparatory position before shearing. The preparatory position is adjusted by the operator who positions a limit switch 1a or arranges a control stop either of which is engaged by lower blade 1 when it reaches the intended preparatory position. If t is P tion is defined by the position of a limit swit switch closes an electrical control circuit which opens normally closed valve 47. If the prepa t y P i is defined by a stop arresting blade 1, the resultmg pressure increase in cylinder 7 is made to actuate a1. pressure switch which in turn closes an electric contro circuit to open valve 47. The output P p 15 15 now substantially directed into manifold 136 for actuating movement of differential piston 3739. I

Positioning of upper b a 4 In a Preparatory Position before shearing is initiated by shifting of valve 14 whlch is preferably linked to valve 18 for simultaneous operation. In order to cause descent of upper blade 4 from the inoperative into the preparatory position, valve 14 directs the output of pump 15 through valve 17 into cylinders 11 while simultaneously permitting hydraulic fluid tov return from cylinders 9 to the sump 46 at a ratev controlled by throttle bypass 13.

When upper blade 4 reaches the predetermined preparatory position, it may either actuate a limit switch 411 or abut against the Work piece to be sheared so as to cause pressure to build up in cylinder 11 for actuating a pressure switch of control means in the same manner in which the corresponding elements cooperate with the lower blade 1. Whichever control device is used for determining the preparatory position of upper blade 4, valve 17 is switched as soon as upper blade 4 reaches the predetermined preparatory position so as to direct the output of pump 15 into manifold 136.

When both shearing blades have reached their respective preparatory positions and thus have actuated respective limit switches or pressure switches, a common control circuit including the switches of both blades in series is energized to shift the positions of valves 31 to 36 and to connect the outputs of pumps 25 to 30 to manifold 136 whereby the differential piston 37-39 causes water under pressure to be supplied to operating cylinder 3 and the shearing operation is started.

When the blades 1 and 4 meet and shearing is completed, an additional limit switch is actuated and all valves are returned to their initial positions except valve 14 which is set for connecting the output of pump 15 to cylinders 9 through check valve 12 so as to return upper blade 4 to its inoperative position, the water contained in cylinder 3 is thereby pressed into cylinder 38 until the differential piston 3739 is returned to its lowest position and thereby opens valve 43 whereupon any water still present in cylinder 3 flows into tank 41.

The arrangement described above makes particularly effective use ofthe various hydraulic pumps employed for actuating the movements of the shear blades. The pumps which supply pressure fluid for moving the blades from their inactive to their preparatory positions before shearing are thereafter utilized to assist in providing pressure for the operating or shearing movement of the blades.

This is achieved by linking all the pumps of the power shears into a common manifold under relatively low pressure and transforming the energy of a relatively large volume of relatively low-pressure fluid into the high pressure of a smaller body of secondary hydraulic fluid. This separation of the power generating from the power consuming part of the hydraulic circuit permits the use of water in the highpressure circuit where leakage losses are most likely to occur, and to use oil in the low-pressure circuit without causing corrosion of the Pumps and Valves- The power shears of the invention are made to work fully automatically, once they are started, y the Intel" locking of a system of remote-control valves and of control switches actuating the valves and themselves controlled by the positions of the shearing blades. The switches are either actuated by mechanical elements connected to the blades and mechanically acting on the switches, or the pressure surge occurring in hydraulic cylinders driving a blade when the movement of the blade is stopped by an abutment is utilized to actuate a switch which in turn causes movement of a valve.

The automatic arrangement uses but a relatively small number of rugged and inexpensive elements and is, therefore, rugged and inexpensive itself. Individual switches or valves may readily be replaced for main tenance purposes.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of hydraulic power shears different from the types described above. While the invention has been illustrated and described as embodied in power shears it is not intended to be limited to the details shown, as its various modifications and structural changes may be made without departing in any way from the spirit of the present application.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1 In a hydraulically operated arrangement, in combination, a ram memberr for moving said member from moving said member from said preparatory position into operative position; two independent hydraulic pump valve means movable between first and second paratory to said operating position thereof by the combined action of both hydraulic pump means.

2. In a shearing arrangement, in combination, a shearing blade; hydraulic positioning piston means for moving said blade from an inoperative into a preparatory position before shearing; hydraulic operating piston means for moving said blade from said preparatory position into operative shearing position; limit switch means sensitive to the position of said blade; two independent hydraulic pump means; valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving said blade from inoperative into preparatory position, and for then connecting said one piston means; control means actuated by said limit switch means in said'preparatory position of said blade to move said valve means to said second position; and valve means for connecting the other of said hydraulic pump means to said operating piston means only when said blade is pump means to said operating.

in said preparatory position thereof, so that said blade is moved from said preparatory to said operating position thereof by the combined action of both hydraulic pump means.

3. In a shearing arrangement, in combination, a shearing blade; hydraulic positioning piston means for moving said blade from an inoperative into a preparatory position before shearing; hydraulic operating piston means for moving said blade from said preparatory position into operative shearing position; two independent hydraulic pump means; pressure switch means sensitive to the hydraulic pressure acting upon said positioning piston means; abutment means in the form of a workpiece for arresting movement of said blade in said preparatory position so that the hydraulic pressure acting upon said positioning piston is increased when said blade reaches the preparatory position thereof; valve means for connecting one of said pump means first to said positioning piston means for moving said blade from inoperative into preparatory position, and then actuated by said pressure switch means for connecting said one pump means to said operating piston means; and valve means for connecting the other of said hydraulic pump means to said operating piston means only when said blade is in said preparatory position thereof, so that said blade is moved from said preparatory to said operating position thereof by the combined action of both hydraulic pump means.

4. In a shearing arrangement, in combination, a shearing blade; hydraulic positioning piston means for moving said blade from an inoperative into a preparatory position before shearing; hydraulic operating piston means for moving said blade from said preparatory position into operative shearing position; two independent hydraulic pump means; valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving said blade from inoperative into preparatory position, and for then connecting said one pump means to said operating piston means; control means actuated by said blade in said preparatory position to move said valve means to said second position and valve means actuated by said control means for connecting the other of said hydraulic pump means to said operating piston means only when said blade is in said preparatory position thereof, so that said blade is moved from said preparatory to said operating position thereof by the combined action of both hydraulic pump means.

5. In a shearing arrangement in combination, a shearing blade; hydraulic positioning piston means for moving said blade from an inoperative into a preparatory position before shearing; hydraulic operating piston means for moving said blade from said preparatory position into oper ative shearing position including an operating piston, and differential piston means hydraulically connected with said operating piston for increasing the fluid pressure acting on the same; two independent hydraulic pump means; valve means movable between finst and second positions for connecting one of said pump means first to said positioning piston means for moving said blade from inoperative into preparatory position, and for then connecting said one pump means to said operating pistonmeans; control means actuated by said blade in said preparatory position to move said valve means to said second position; valve means for connecting the other of said hydraulic pump means to said operating piston means only when said blade is in said preparatory position thereof, so that said blade is moved from said preparatory to said operating position thereof by the combined action of both hydraulic pump means.

6. In a shearing arrangement, in combination, a shearing blade; hydraulic positioning piston means for moving said blade from an inoperative into a preparatory position before shearing; hydraulic operating piston means for moving said blade from said preparatory position into operative shearing position including an operating piston, and diiferential piston means hydraulicaliy connected with said operating piston for increasing the fluid pressure acting on the same; two independent hydraulic pump means; first valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving said blade from inoperative into preparatory position and for then connecting said one pump means to said operating piston means; control means actuated by said blade in said preparatory position to move said valve means to said second position; second valve means actuated by said control means for connecting the other of said hydraulic pump means to said operating piston means only when said blade is in said preparatory position thereof, so that said blade is moved from said preparatory to said operating position thereof by the combined action of both hydraulic pump means.

7. In a hydraulic system, in combination, hydraulic positioning piston means for moving an object from an inoperative to a preparatory position; hydraulic operating means including an operating cylinder and an operating piston movable in said operating cylinder for moving the object from said preparatory position to an operative position, a separating cylinder and a separating piston in the same defining two chambers in said separating cylinder, one of said chambers being adapted to contain a first operating liquid, and a conduit means connecting said one chamber with said operating cylinder so that said operating piston is operated by said first liquid; two independent pump means for pumping a second liquid; valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving the object from said inoperative to said preparatory position, and for then connecting said one pump means to the other chamber of said separating cylinder so that said second liquid enters said other chamber; control means actuated from said operating piston in said preparatory position to move said valve means to said second position; and another valve means for connecting the other of said pump means to said other chamber of said separating cylinder only when the object is in said preparatory position so that said second liquid enters said other chamber whereby said separating piston moves under the pressure of said second liquid pumped by both said pump means to press said first liquid into said operating cylinder so that the object is moved from said preparatory position to said operation position.

8. In a hydraulic system, in combination, hydraulic positioning piston means for moving an object from an inoperative to a preparatory position; hydraulic operating means including an operating cylinder and an operalting piston movable in said operating cylinder for moving the object from said preparatory position to an operative position, a separating differential cylinder and a separating differential piston in the same defining two chambers in said separating cylinder, one of said chambers having a smaller cross section than the other chamber and being adapted to contain a first operating liquid, and a conduit means connecting said one chamber with said operating cylinder so that said operating piston is operated by the first liquid; two independent pump means for pumping a second liquid; valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving the object from said inoperative to said preparatory posit-ion, and for then connecting said one pump means to said other chamber of said separating cylinder so that said second liquid enters said other chamber; control means actuated from said operating piston in said preparatory position .to move said valve means to said second position; and another valve means for connecting the other of said pump means to said other chamber of said separating cylinder only when the object is in said preparatory position so that said second liquid enters said other chamber whereby said separating piston moves under the pressure of said second liquid pumped by both said pump means to press said first liquid into said operating cylinder so that the object is moved from said preparatory position to said operating position.

9. In a hydraulic system, in combination, hydraulic positioning piston means 'for moving an object from an inoperative to a preparatory position; hydraulic operating means including an operating cylinder and an operating piston for moving the object from said preparatory position to an operative position; two independent pump means; valve means movable between first and second positions for connecting one of said pump means first to said positioning piston means for moving the object from said inoperative to said preparatory position, and for then connecting said one pump means to said operating cylinder; control means actuated from said operating piston in said preparatory position to move said valve means to said second position and another valve preparatory position so that the object is moved from;

said preparatory position to said operating position by the combined action of both said pump means.

References Cited in the file of this patent UNITED STATES PATENTS 786,236 Ross Mar. 28, 1905 2,058,377 Francis Oct. 20, 1936 2,403,912 Doll July 16, 1946 2,573,993 Sedgwick Nov. '6, 1951 2,649,154 Adrian Aug. 18, 1953 2,699,649 Messic'k Jan. 18, 1955 2,811,838 Lindsey Nov. 5, 1957 2,825,405 Maass Mar. 4, 1958 2,839,895 Hemeon June 24, 1958 2,877,624 Zoller Mar. 17, 1959 FOREIGN PATENTS 265,252 Germany Oct. 4, 1913

Claims

1. IN A HYDRAULICALLY OPERATED ARRANGEMENT, IN COMBINATION, A RAM MEMBER; HYDRAULIC POSITIONING PISTON MEANS FOR MOVING SAID MEMBER FROM AN INOPERATIVE INTO A PREPARATORY POSITION; HYDRAULIC OPERATING PISTON MEANS FOR MOVING SAID MEMBER FROM SAID PREPARATORY POSITION INTO OPERATIVE POSITION; TWO INDEPENDENT HYDRAULIC PUMP MEANS; VALVE MEANS MOVABLE BETWEEN FIRST AND SECOND POSITIONS FOR CONNECTING ONE OF SAID PUMP MEANS FIRST TO SAID POSITIONING PISTON MEANS FOR MOVING SAID MEMBER FROM INOPERATIVE INTO PREPARATORY POSITION, AND FOR THEN CONNECTING SAID ONE PUMP MEANS TO SAID OPERATING PISTON MEANS; CONTROL MEANS ACTUATED BY SAID MEMBER IN SAID PREPARATORY POSITION TO MOVE SAID VALVE MEANS TO SAID SECOND POSITION; AND VALVE MEANS FOR CONNECTING THE OTHER OF SAID HYDRAULIC PUMP MEANS TO SAID OPERATING PISTON MEANS ONLY WHEN SAID MEMBER IS IN SAID PREPARATORY POSITION THEREOF, SO THAT SAID MEMBER IS MOVED FROM SAID PREPARATORY TO SAID OPERATING POSITION THEREOF BY THE COMBINED ACTION OF BOTH HYDRAULIC PUMP MEANS.