US3393635A - Independently operable press brakes having tandem coupling means - Google Patents

Description

y 3. 1968 R. A. RICHARDSON 3,39

INDEPENDENTLY OPERABLE PRESS BRAKES HAVING TANDEM COUPLING MEANS Filed Aug. 25, 1966 2 Sheets-Sheet 1 IN VEN TOR ROL Lgzva ARIOHARDSON WARREMBROSLEIBGYPHER 8 ANG'LIM .4 T T ORA/E Y3 July 23. 1968 TANDEM COUPLING ME ANS 2 Sheets-Sheet 2 Filed Aug. 25. 1966 mm a W )W M w M w m w a i 1 A w W m L wfl "a 6 "WW. I v a m: B 1 m 4. M H Z 5 IN VE N T 0/? ROL LAND .4 RICHARDSON WARREN, BROSLER, GYPHE'R 8 AWGLIM ATTORNEYS United States Patent 3,393,635 INDEPENDENTLY OPERABLE PRESS BRAKES HAVING TANDEM COUPLING MEANS Rolland A. Richardson, Alameda, Calif., assignor to Pacific Press & Shear Corp., a corporation of Illinois Filed Aug. 25, 1966, Ser. No. 575,146 Claims. (Cl. 10043) ABSTRACT OF THE DISCLOSURE Two or more independently operated machines such as press brakes are positioned in end to end relationship. There being provided coupling means between the machines whereby to be responsive to a prevailing non-synchronous relationship between the machines for establishing a synchronous rate of travel of the movable parts of the machines.

My invention relates to machines such as press brakes or the like employing rams, and more particularly to the tandem operation of such machines.

Occasionally in the fabrication of items of manufacture requiring the use of a press brake or the like, the size of the item exceeds that of the dimensional capacity of the machine to handle the same. The frequency at which this happens may not be such as to warrant the purchase of machines large enough to handle this type of work. It has been found, however, that two or more smaller machines may be operated synchronously in tandem to effectively handle such larger pieces for work.

The problem, however, in this type of operation, is to assure synchronism between the rams of the various machines involved, for should such rams engage the work when not in synchronism, it can very well result in producing a kink in the Work, and this must be avoided.

Among the objects of my invention are:

(1) To provide novel and improved control means for assuring synchronous operation of machines in tandem which are adapted to function in synchronism;

(2) To provide novel and improved control means for assuring synchronous operation of the rams of adjacently disposed machines such as press brakes or the like;

(3) To provide novel and improved control means for selectively operating press brakes or the like, individually or in synchronism;

(4) To provide novel and improved means for tandem coupling the rams of adjacently disposed machines without impairing the ability of such machines to function independently of each other, and without altering the effective coupling between the rams thereof.

Additional objects of my invention will be brought out in the follow-ing description of a preferred embodiment of the same, taken in conjunction with the accompanying drawings, wherein;

FIGURE 1 is a schematic view depicting the system of the present invention as applied to a pair of press brakes in tandem,

FIGURE 2 is a circuit diagram depicting the pertinent portion of the electrical circuit involved in converting press brakes of FIGURE 1 from operation as independent machines to operation in tandem,

FIGURE 3 is a front view in elevation of a free coupling between rams to be operated in tandem,

FIGURE 4 is a side view in elevation of the free coupling illustrated in FIGURE -3, and

FIGURE 5 is a view depicting an extension of the invention to encompass an indefinite number of machines operating in tandem.

For the purposes of the present invention, only a brief description of the individual machine is necessary, and

3,393,635 Patented July 23, 1968 then only the pertinent portions thereof involved in the operation of the present invention.

Such machine includes a ram 1 reciprocally mounted for cooperation with a suitable die (not shown). The ram is driven or powered by a pair of hydraulic motors 3 and 5, one at each end of the ram and including a cylinder 7 mounted on the frame of the machine, and a piston 9 coupled to the ram at a proximate point thereof.

The hydraulic motors are supplied hydraulically by a pair of pumps 11 and 13. The particular hydraulic systems whereby these pumps supply the hydraulic motors are of little moment insofar as the present invention is concerned, but in the specific embodiment illustrated, and for purposes of explaining the present invention, a flow line 15 from each pump is divided into two flow line branches 17 and 19. One branch -17 extends to the upper end of the cylinder of one of the hydraulic motors, and includes a normally closed valve assembly 23 controlled by a normally closed pilot valve 24 which, in turn, is electrically actuated by a solenoid winding 25. Downstream of the valve assembly 23, this flow line is adapted to be flow connected to tank 26 through a normally closed valve assembly 27 controlled by a normally open pilot valve 29, which in turn, is electrically actuated by a solenoid winding 31.

The other branch 19 which leads to the lower end of the cylinder of the other hydraulic motor, includes a normally closed valve assembly 33 controlled by a normally closed pilot valve 35 which is electrically actuated by a solenoid winding 36. Downstream of this valve assembly as viewed from the pump, the branch flow line 19 is adapted to be flow connected to tank 26 through a normally closed valve assembly 37 controlled by a normally open pilot valve 38 which is electrically actuated by a solenoid winding 39.

In addition to the foregoing, each pump is adapted to be directly flow connected to tank 26 through a normally closed overload relief valve assembly 41, adapted to be opened by a normally open pilot valve 43 Which is electrically actuated by a solenoid winding 45.

During neutral or rest condition of a machine embodying such hydraulic systems as described above, only the solenoid actuated pilot valves 29 and 38 associated with those valve assemblies which are adapted to flow connect the branch lines 17 and 19 to tank, are energized, which results in closing these pilot valves, thereby causing the associated valve assemblies to block discharge from any of the branch lines to tank.

The pilot valve 43 associated with each overload relief valve assembly 41, being a normally open valve, both pumps will be flow connected to tank, thus shunting the hydraulic motors, and the machine under these conditions cannot function.

To initiate a down or work stroke, the pilot valves 38 controlling. the valve assemblies 37 in the discharge to tank from the branch lines 19, are de-energized to establish such -flow connection.

At the same time, the pilot valves 43 associated with the overload relief valves 41 are energized to block discharge to tank from the pumps, except under overload conditions. Also, the pilot valves 24 controlling the valve assemblies 23 in the branch lines 17 to the upper ends of the cylinders, are energize-d to unblock these flow lines.

Under the conditions thus established, each pump will be connected to the upper end of one of the cylinders, with liquid flow provided from the lower end of such cylinder to tank, thereby directing hydraulic power to the upper ends of the pistons, which will cause downward travel thereof and a resulting work stroke of the ram.

Upon completion of such work stroke, the pilot valves 24 are de-energized to block the lines 17 at these points. At the same time, the pilot valves 29 associated with the valve assemblies 27 which place these lines in flow connection with tank, are de-energized to establish such flow connections.

In the other branch lines, the pilot valves 38 which control discharge to tank from such lines are re-energized to block such discharge. At the same time, the pilot valves associated with the valve assemblies 33 included in such lines, are energized to unblock these lines to establish flow therethrough. The net efiect of all this is to reverse the branch lines 17 and 19 in respect to flow therethrough, with each pump flow connected to the lower end of the other cylinder and establishing connections for an upstroke.

The pilot valves 43 controlling the overload relief valves 41 are maintained in their energized conditions to permit such upstroke, until such upstroke has been completed, at which time, these pilot valves are tie-energized to place the pumps in flow communication with tank.

The foregoing brief description of the manner of operation of the type of machine to which the present invention is applicable, while not a part of the present invention, is essential toward an understanding of the same. A more comprehensive description of a similar machine to which the present invention will be applicable, may be had by reference to my prior Patent No. 2,906,- 096 of Sept. 29, 1959 for Precision Control System for Press Brakes or the Like.

The electrical circuits of each machine are controlled through a foot operated switch 49. Insofar as the present embodiment of the invention is concerned, such switch, in its normal rest position, connects in circuit across a pair of power lines, 51 and 53, the solenoid windings 39 of the valve assemblies 37. These, it will be recalled, function, when energized, to block discharge from branch lines 19 to tank. When depressed, such foot switch opens this circuit to solenoid windings 39, and closes another circuit through solenoid windings 25 of valve assemblies 23 and solenoid windings of the overload relief valv assemblies 41, all of which winding-s are in parallel. The net result of depressing the foot switch of a machine will therefore be the initiation of a work stroke of the ram of such machine.

To relate two or more such machines for tandem operation, they are physically installed closely adjacent to each other with their rams in a common plane.

A further requirement toward realizing tandem operation, is to be able to simultaneously energize all machines involved. An arrangement for accomplishing this is included in the circuitry of FIGURE 2.

With each of said machines normally under control of its own foot switch 41, all foot switches would, in the absence of other arrangements, have to be depressed simultaneously, which in itself would pose quite a problem. To avoid this problem, I provide means for utilizing but one of the available foot switches to control the operation of all machines.

Where only two machines are involved, I provide a pair of relays 55 and 57, one of which includes at least one pair of normally closed contacts 59 and two pairs of normally open contacts 61 and 63, while the other relay includes at least two pairs of normally closed contacts 65 and 67, and one pair of normally open contacts 69.

The foot switch circuits of the one machine are so connected through the contacts of these two relays, to the circuits of the other foot switch, that upon energization of the relays, the windings 39, 26 and 45 associated with the operation of one foot switch are connected in parallel with the corresponding windings associated with the other foot switch, whereby all such windings will be under control of the one foot switch.

In accomplishing this, a paralleling connection 71 is installed between the lines leading to the corresponding windings energized through the normally closed contacts of the foot switches, and in this paralleling connection are the normally open contacts 63 of the relay 55. In similar manner, a paralleling connection 73 is installed between the lines leading to the windings which are energized through the normally open contacts of the foot switches, and in this paralleling connection are a pair of normally open contacts 69 associated with the other relay 57. Basically such paralleling connections, when closed, will not, in and of themselves, serve to assure power to their associated windings in parallel, for without other precautionary measures, such connections will at the same time form a series connection between the switches and thus by-pass the windings.

To forestall this, the pair of normally closed contacts 65 are connected in the power lead to the normally closed contacts of the foot switch of the other machine, and a similar pair of normally closed contacts 67 in the line leading from said contacts to the solenoid windings 39 normally connected thereto.

With regard to the other foot switch, which is to control operation of both machines in tandem, a pair of normally closed contacts 59 are connected in the line leading from the normally open contacts of said foot switch, to the parallel connected windings 25 and 45, while a pair of normally opened contacts 61 of relay 55 are connected in circuit between a point 75 of said line to a point on the paralleling connection 73 below the contacts 69.

The relays 55 and 57 controlling the aforementioned contacts, are connected in parallel across the power leads through a normally open manually controlled switch 79, whereby upon closing of such switch. both machines will be placed under control of one foot switch, this assuring that both machines will start operating simultaneously.

However, such simultaneous starting of the machines will not necessarily assure synchronism in the movement of the rams thereof, because of prior independent operation of such machines, the starting position of the rams may not be identical. It remains therefore to assure that such rams shall reach synchronism before either engages the work.

In providing for synchronised control of the rams, a flow line 31 from the output of each pump of a machine joins in a common line 83 which leads to the tank of such machine, and installed in such common line is a continuously variable valve assembly 85 or 86.

Such valve assembly may be of the type known as a proportional valve assembly involving a housing 89 with a cylindrical bore in which is slidably installed a spool valve 91 having a control stem 93 emerging from the housing and terminating in a roller 94. The spool is biased in one direction by a spring 95. By coupling the stems of these valves to appropriate control means, one can then effect a bleeding off of hydraulic medium from that machine in which the ram may be leading, to permit the ram of the other machine to catch up and assume synchronism with the first machine, at which time, both valves may be caused to be in their shut off condition.

To assure that these valve controlled bleeder lines will function only when tandem operation of the machines is desired, the lines from both machines include corresponding valve sections of a normally closed multiple valve assembly 99, which is preferably controlled by a solenoid winding 101 and capable of unblocking such lines by energizing the solenoid winding.

A check valve 103 in each bleeder flow line from a pump, will serve to isolate such pump from the hydraulic system serviced by the other pump in a machine.

In controlling the bleeder valve assemblies 85, 86 to bring about synchronization of the rams, such valve assemblies are made responsive to the relative positions of such rams. Toward this end, I provide a cam bar 107 adjacent the proximate edge of one of the rams, such cam bar having an intermediate sloping cam surface 109.

Carried by a bracket affixed to the adjacent ram and extending across the intervening space between the two rams, are the bleeder valve assemblies 85, '86, with their respective surface engaging rollers 94 held in light pressure contact with the cam bar by the valve springs 95-. When both valve assemblies are to be thus mounted on the same ram and on a common bracket in line with one another, they are constructed to function in reverse with respect to each other, and are so adjusted that each will shutoff when its roller is midway of the sloping cam surface.

Under these conditions, one bleeder valve assembly will open when one ram is leading the other rarn, while the other valve assembly will remain closed to permit the other ram to catch up. As the lagging ram approaches synchronism with the first ram, the bleeder valve assembly associated with the leading ram will gradually approach its shut off position, which it will reach when the roller thereof arrives at the mid-point of the sloping cam surface. At this point, both rams will be in synchronism and will complete the work stroke together.

It is important, in this connection, to note that the coupling between the two rams will not in any way interfere with the independent operation of the individual machines, and insofar as operating these machines, independently or in tandem, is concerned, no precautions need be taken to affect any change in the coupling between the rams. Because such coupling permits free and independent movement of the rams relative to each other, such coupling may be termed a free coupling.

While the preferred form of coupling between rams has been depicted as involving a pair of bleeder valve assemblies functioning in reverse to one another, with each valve assembly discharging back to the tank of the machine from which it bleeds the hydraulic fluid, both valve assemblies may be incorporated into a single unit, discharging to the same tank, but in such event, some means, such as an interconnecting pipe between tanks, must be provided to assure that the supply of hydraulic fluid for any individual machine shall not be diminished.

Also, in lieu of the preferred form of coupling as illustrated, various other arrangements and modifications are available while still permitting freedom of the machines to function independently of one another, without necessitating any change in the prevailing coupling.

Should the rams of tandem connected machines be so far out of synchronism before initiating a down stroke, that the lead ram might conceivably strike the work before synchronism can be realized, I provide a pair of limit switches, one for each machine, and adapt it to prevent operation of the lead machine until the lagging ram of the other machine approaches sufficiently close to synchronism as to enable the bleeder valve assemblies to function and to bring the two rams into synchromism before the work stroke can be completed.

With this in mind, I provide another cam surface 111 similar to the first, and preferably on the same cam bar, and on the other ram, in association with the added cam surface, are a pair of micro switches 113, 115.

These micro switches are preferably slightly displaced vertically with respect to each other, and like the bleeder valves, will preferably be designed to function in reverse, one with respect to the other. When the rams are sufficiently close to synchronism that these micro-switches will be symmetrically located with respect to their associated cam surface, both will be open, but each is adapted to close when the ram of the machine with which the switch is electrically associated, is leading to such a degree that the switches are not symmetrically disposed on the cam surface. When closed, either micro-switch will render its associated machine inoperable and thus cause it to stay put until the ram of the lagging machine approaches synchronism with the other ram and the bleeder valves can take over to complete the job of establishing synchronism before completion of a work stroke by both rams.

From the viewpoint of circuitry, each micro-switch 6 113, controls a circuit through a relay 119, 121 respectively, such circuits including in common, the manually operable switch 79. In parallel with the microswitches and their associated relays, is the solenoid winding 101 which controls the multiple valve assembly 99 in the bleeder lines to the bleeder valves.

Each of the micro-switch controlled relays includes a pair of normally closed contacts 125 in circuit with the solenoid windings 45 of the pilot controlled overload release valve assemblies 41 of a machine, which when energized, serve to hydraulically couple both pumps of the pertinent machine to tank, and thereby render that machine inoperable so long as such condition prevails.

Accordingly, should the rams be so far out of synchronism, that the bleeder valves are riding a vertical surface of the cam bar when operation of the machines in tandem is desired, the micro-switch associated with the relay of the lead machine will close, to energize such relay and cause its normally closed contacts to open and de-energize the solenoid windings 45 of the overload relief valve assemblies associated with the pumps of the lead machine. This will cause such pumps to deliver directly to tank and thus render that machine inoperable so long as such condition exists. Since this machine cannot function, its ram will stay put until the ram of the lagging machine approaches synchronism, which means that the microswitches are riding the cam surface 111 and approaching their position of symmetry with respect to said cam surface.

As the symmetrical position is reached, the functioning micro-switch will open its contacts to de-energize its associated relay, which in turn will permit its contacts to close and reenergize the solenoid windings 45. This renders the lead machine operable and subject to control of the bleeder valves, the pertinent one of which will bleed olf liquid from the hydraulic systems of the lead machine at a rate which will decrease as the rarns approach closer and closer to synchronism, at which point the functioning bleeder valve will shut off and both rams can then proceed to complete the work stroke in synchronism.

To assure that the bleeder valves shall have an opportunity to function, they are preferably so mounted that they do not reach the mid-point of their cam surface 109 until just slightly after the functioning micro-switch opens.

Insofar as the return stroke of the rams is concerned, synchronism is not essential, and it would be desirable, therefore, to render these synchronising circuits inoperative during such return stroke. This is a relatively simple matter, and can be accomplished by opening such circuits by means of normally closed contacts 131, 133, 135, etc. associated with an up relay or some equivalent relay, normally found in the circuits of press brakes and the like, and which are energized to effect an up or return stroke of a ram.

From the foregoing description of my invention in its preferred form, it will be apparent that the same fulfills all the objects of my invention, and in a very simple and positive manner. The closing of one manual switch is all that is necessary to convert a plurality of machines from individual operation to operation in tandem, no precautions being necessary to adjust or change any coupling between the rams of the machines, and this is an important feature of the present invention.

Accordingly, while I have illustrated and described my invention in its preferred form and in great detail, it will be apparent that the same is subject to alteration and modification without departing from the underlying principles involved, and I accordingly do not desire to be limited in my protection to the specific details illustrated and described, except as may be necessitated by the appended claims.

I claim:

1. In combination, at least two independently operable machines, each having a movable component capable of moving in synchronism with the other, means adapted to apply power simultaneously to said movable components, and control means responsive to a prevailing non-synchronous relationship between said components for unbalancing power to said components in the direction of establishing synchronism, and adapted upon arriving at synchronism, for establishing a synchronous rate of travel of said components.

2. A combination as recited in claim 1 characterized by said movable components including the rams of independently operable press brakes or like machines, said machines being so disposed as to place said rams adjacent one another and substantially end to end in a common plane.

3. A combination as recited in claim 2 characterized by said means for applying power simultaneously to said rams as including a pair of hydraulic motors for each ram, a pump for each said hydraulic motor and having a normally inactive flow connection to said hydraulic motor, and means for simultaneously activating said flow connections to said hydraulic motors.

4. A combination as recited in claim 3, charactrized by said control means as including a hydraulic flow line from each of said pumps in by-pass relationship about its associated hydraulic motor, and means for modulating flow in said by-pass flow lines to establish synchronism between rams of adjacent machines.

5. A combination as recited in claim 4 characterized by said flow modulating means including bleeder valve means in said by-pass flow lines, and means controlled by the relative positions of adjacent rams with respect to each other, for adjusting said bleeder valve means in the direction of establishing synchronism between said rams.

6. A combination as recited in claim 5, characterized by said control means as also including means responsive to an out of synchronous condition beyond a point approaching synchronism, for rendering the lead machine inoperable until the ram of the lagging machine approaches synchronism and permits said bleeder valve means to function.

7. A combination as recited in claim 6, characterized by said bleeder valve means as including a pair of bleeder valve assemblies mounted one ram adjacent the other ram, said bleeder valve assemblies being operable in reverse with respect to each other and having cam actuable 8 means, and cam means on said other ram with a cam surface symmetrically disposed in contact with said cam actuable means when said rams are in synchronism, and said means for rendering the lead machine inoperable until the lagging machine approaches synchronism includes a pair of microswitches mounted on one ram and cam means on the other ram having a cam surface symmetrically engageable with said micro-switches when said rams are in synchronism.

8. In combination, a pair 'of press brakes each having a movable ram, said press brakes being located with their rams disposed in a common plane in slight spaced end to end relationship, and a variable coupling mounted on said rams across the space between them, said coupling being adapted to vary with change in out-of-synchronism relationship between said rams and permitting free and independent movement of each ram for individual machine operation.

9. A combination as recited in claim 8, characterized by said synchronizing coupling including a cam mounted on one of said rams and valve means mounted on the other of said rams, said valve means having a valve actuating mechanism in pressure contact with said cam.

10. A combination as recited in claim 9, characterized by said synchronizing coupling also including additional cam means on one ram and a pair of micro-switches on the other ram in engagement with said additional cam means, said microswitches being displaced vertically and actuable in reverse with respect to each other, from a normally open condition, by said cam means.

References Cited UNITED STATES PATENTS Re. 26,236 7/1967 Hazelton et al. 91-171 604,364 5/1898 Brown 91171 722,676 3/1903 Clarke 91171 1,900,050 3/ 1933 Ernst. 1,947,253 2/1934 Ellis 91171 2,400,685 5/ 1946 Collins. 2,764,869 10/1956 Scherr 91-17l 2,851,860 9/1958 Lindsey. 3,199,443 8/1965 Danly 207 BILLY J. WILHITE, Primary Examiner.

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