US2931182A - Hydraulic shear - Google Patents

Description

R. P. ANDERSON ET AI. 2,931,182

HYDRAULIC sHEAR 5 Sheets-Sheet 1 ....q, I-l IVI. .II .IlIlIvlllH IIIIPIIIII K April 5, 1960 Filed Aprille', 1957 INVENTORS Pay 05x04 By Rap/f EAA/@Epson III III

I I I I I I l l I I I I I I I I l I I I IM @S April 5, 1960 R. P. ANDERSON r-:TAL 2,931,182

HYDRAULIC SHEAR n Filed April 15, 1957 5 Sheets-Sheet 2 .Il l MN April 5, 1960 R. P. ANDERSON E-rAL 2,931,182

HYDRAULIC SHEAR Filed April 16, 1957 5 Sheets-Sheet. 3

INVENToRs Por f-T DEH/v BY RALPH RANQERSON April 5, 1960v R. P. ANDERsoN ETAL 2,931,182

HYDRAULIC sHEAR Filed April 16, 1957 5 Sheets-Sheet 4 @XR m f @i LJ sw/ R d [im Q E? @A [t Q gg nx.) y@

April 5., 1960 R. P. ANDERSON Erm. 2,931,182

HYDRAULIC SHEAR 5 Sheets-Sheet 5 Filed April 16, 1957 INVENTUM` Psy E OEHN By PAL/H EAA/msm t. l m, '1.'

Armas-Ys United States HYDRAULIC SEMAR Application April 16, 1957, Serial No. 653,238

4 Claims. (Cl. 60-97) The present invention relates to devices having a movable member actuated by a plurality of reciprocating type hydraulic motors and wherein it is necessary or desirable to have the movable member travel or move in a predetermined manner with respect to a stationary member or some predetermined reference plane.

One of the principal objects of the invention is the provision of a novel and improved device for cutting or otherwise fabricating sheet material or the like, for example, a shear, platen press, press brake, etc., having a movable member of substantial size in at least one dimension actuated by a plurality of reciprocating type double acting hydraulic motors connected to the movable member at relatively widely spaced points which machine will be relatively light in weight, simple in design and rigid in construction, reliable in operation and which comprises means for supplying pressure uid to the respective motors in such a manner that the movable member moves, preferably in both directions, in a relatively exact or precise predetermined attitude or manner, for example, parallel with or inclined at a predetermined angle to the stationary platen, blade, etc.

A more specific object of the invention is the provision of a novel and improved metal working shear or press brake having an elongated movable blade actuated by a pair of reciprocating type double acting uid pressure operated motors connected to the movable blade adjacent to opposite ends thereof in combination with means for supplying pressure fluid to the motors and including a Wheatstone bridge responsive to deviation of the blade from a predetermined attitude relative to the stationary blade or die for controlling the relative ow of pressure uid to the motors whereby the blade is automatically restored to the predetermined attitude or a predetermined attitude is maintained.

Another of the principal objects of the invention is the provision of a novel and improved means for controlling the supply or flow of fluid pressure to a plurality of reciprocating type hydraulic motors preferably of the double acting type such that the motors are operated in precise predetermined relation to one another.

The invention resides in certain constructions and combinations and arrangements of parts and further objects and advantages will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification in which similar reference characters designate corresponding parts and in which Fig. 1 is a front elevational View of a sheet metal or plate shear embodying the present invention;

f Fig. 2 is a rear view of the shear shown in Fig. 1;

. Fig. 3 is a sectional view of the shear approximately on the line 3 3 of Fig. l;

. Fig. 4 is a diagrammatic view showing the hydraulic system and the mechanical part of the leveling control; and

arent Fig. 5 is a wiring diagram showing the electrical control for the shear.

The present invention is considered especially applicable to sheet metal or plate shears and bending brakes and is herein shown as embodied in such a shear. The invention however, is applicable to various types of shears, presses and other machines utilizing multiple pressure fluid operated reciprocating type motors and the present showing is intended to be merely illustrative of the invention and not to be restrictive in any manner.

Referring to the drawings, the shear shown includes a frame A comprising stress-resisting, plate-like end members or side housings 10, 11 having aligned openings 12, 13 respectively, in their front edges; a crown 14 connecting the upper ends of the side housings 10, 11; and a table 15 supported upon and fixedly secured to the top of forwardly projecting parts of the side housings 10, 11 and a heavy plate or stationary blade 16 extending between and fixedly secured to the side housings 10, 11.

A movable ram or upper blade, designated generally by the reference character B, extends substantially from one side housing to the other and is of built-up construction. As shown, the movable ram or blade B comprises a longitudinally extending front plate 20 welded to the front ends of rearwardly extending members 21, 22, the rear ends of which are rotatably connected to short, shaftlike members 23, 24 rotatably supported in suitable apertures in the side housings 10, 11, respectively, for rotation about an axis eccentric to the axis about which the members 21, 22 are connected thereto. The axis about which the ram or blade B is pivoted is preferably slightly above the plane of the work supporting surface of the table 15.

In addition to the front plate 20 and the members or plates 21, 22 the movable ram or upper blade B comprises a lbotto-n1 plate 25 having an upwardly extending rear flange 26. The ends of the front edge of the bottom plate 25 abut against and are welded to the rear side of the plate 20 adjacent to the lower edge thereof While the ends thereof are welded to the members 21, 22. The intermediate part of the front edge of the bottom plate 25 is welded to a plate 27 spaced slightly to the rear of the plate 20. The blade assembly is further reinforced by web members 29, Sil, 31, 32, 33 welded to the plates 20, 27 and the bottom plate 25 and by triangular plates weldedto the rear side of the bottom plate 25 and the members 21, 22.

The shearing operation is performed by a stationary relatively long, narrow, thin shearing knife 40 located in a cutout portion at the upper rear edge of the stationary blade or member 16 and a movable shearing knife 41 of similar shape connected to the lower front edge of the plate 20 of the movable ram or b-lade B. 'I'he plate 20 of the blade B is inclined at a slight angle to the vertical to provide clearance therebetween and the stationary knife 40 when the ram or blade B is oscillated, and the lower front edge of the plate 20 is inclined lengthwise so that the knives 40, 41 will effect a true shearing action.

In the shear press shown, the axis of rotation of the blade B is parallel to the cutting edge of the stationary shearing knife 40, while the cutting edge of the movable shearing knife 41 is inclined lengthwise relative to the cutting edge of the stationary shearing knife 40 and to the axis of rotation of the blade B. Preferably the stationary knife 40 has a straight or linear cutting edge. With such an arrangement, to efect a uniform clearance between the cutting edges of the shearing knives throughout their ,longitudinal length during shearing movement of the blade B, the movable shearing knife 41 must have its cutting edge positioned on the surface of a cylinder the center of which is coincidentY with the axisof rota tion of the blade B, i.e. its cutting edge must be curved l outwardly a slight amount so as to form a segment of a helix having a very long pitch and an axis coincident with theaxiswof rotation of blade B. The movable blade B and the knife 41 carried thereby are adjusted toward and from the stationary blade C and knife 4t! carried thereby to adjust the clearance between the` knives by rotation or adjustment of the eccentric shaft- like members 23, 24.

The front end of the ram or movable blade B is supported and the entire blade assembly is adapted to be oscillated about the shafts 23, 24 by reciprocating type double acting fluid pressure motors designated generally by reference characters E and F. The cylinders 47, 48 of the motors E and F, respectively, are connected to the crown 14 of the press and the piston rods 59, 51 of the motors are connected by links 52, 53 to pivot pins 54, 55 iixed to the blade B adjacent to opposite ends thereof. Pressure fluid preferably oil, for operating the hydraulic motors is adapted to be supplied 'oy a constant volume unidirectional pump G adapted to be driven Iby an electric motor 56. The pump and motor as well as a number of the other parts of the hydraulic system are supported upon the top of an elongated rectangular oil tank or sump S extending between and connected to opposite end housings 1i), 11 of the frame A.

The ow of uid pressure, preferably oil, to and from the cylinders 47, 48 is controlled by a pair of solenoid operated three-way valves 6), 61 cross connected to the cylinders, that is, each valve is connected to one end on one cylinder and to the opposite end of the other cylinder. In the embodiment shown the valve 60 is connected to the upper end of cylinder 47 and the lower end of cylinder 48 and the -valve 61 is connected to the upper end of cylinder 48 and the lower end of cylinder 47. Both valves 66, 61 are normally spring balanced to their ofic positions wherein the supply conduit 62 therebetween and the pump are connected to the oil reservoir or sump S.

Referring to the wiring diagram and assuming that the motor 56 is in operation and the movable blade B is in its raised position, the blade is caused to move in a downwardly direction by the operator depressing a pedal 65 forming a part of a control box 66 connected to the free end of a flexible electrical cord so that it can be moved to a convenient location. The depressing of the pedal 65 closes a normally open switch 67 establishing an electrical circuit from the alternating current electric power supply line 68 through the normally Aclosed contacts of a mechanical overtravel limit switch 69, wire 76, normally closed contacts 71 of a relay 72, wire 73, now closed contacts of pedal switch 67, wire 74, normally closed down limit switch '75, wire 76, normally closed'interlock contacts 77 of blade up relay 78, wire 79, operating solenoid 80 of blade down relay 81 to power supply line 82. Energization of the operating solenoid 80 of relay 81 closes the normally open contacts `85 thereof which establishes a parallel or holding circuit about the pedal switch 67, assuming that the manually operable on-oi switch 86 is closed. The establishment of the holding circuit about the pedal switch 67 permits the operator to release the pedal switch. lf a manually operable switch 86 is open, the holding circuit will not be established for the pedal switch 67 and the blade down relay 81 will remain energized only so long as the operator holds the pedal switch 67 closed.

f Energization of the operating solenoid 80 of the blade down relay 81, as previously described, opens the normally closed interlock contacts 90 preventing energize.- tion of the blade up relay 78 while the blade down relay 81 is energized. Simultaneously with the closing of the holding contacts 85 and the opening of interlockcontacts 90 of relay 81, normally open contacts 91 thereof close establishing a circuit from the power supply line 68 through the now closed contacts 91 of blade down relay 81, wire 92 and operating solenoids 93, 94 of solenoid valves 60, 61 respectively. Energization of the solenoids 93, 94 shift the valves 60, 61 respectively to the positions in which the supply line 62 from the pump G is connected, through the valve 6i) and the conduit 95 to the upper end of the cylinder 47 and through the valve 61 and the conduit 96 to the upper end of the cylinder 18. The opposite or lower end of the cylinders 47, 48 are simultaneously connected through conduit 97, a counterbalancing valve 98, conduit 99, the valve 61 and conduit 16o to the reservoir or sump S and the lower end of the cylinder 48 is connected in a similar manner by a counterbalancing valve 101 and a valve 60 to the reservoir or sump S. The counterbalancing valves 98, 101 open when the pressure in the lower ends of the cylinders 47, 48 reaches a predetermined pressure and are provided for the purpose of making certain that the movable ram or blade does not drop under its own weight when the valves 69, 61 are in neutral position.

With the respective parts in the operative position referred to the blade continues to move down until the down limit switch '.71 fixed to the frame A and actuated by travel of the movable blade B is opened thus breaking the circuit to the blade down relay 81. When the circuit for this relay is broken its normally closed interlock contacts 913 reclose establishing a circuit from the wire 73 through the now closed interlock contacts 90 of the blade down relay 81, wire 165, normally closed contacts of up limit switch 166, wire 107 and operating solenoid 168 of blade up relay '78 to power supply line 82. The energization of blade up relay 78 opens its normally closed interlock contacts 7"? thus preventing reenergization of blade down relay 81 and closes its nor.- mally open contacts 11).

The closing of the normally open contacts 110 of blade up relay '78 establishes a circuit from the power supply line 68 through the now closed contacts 110 of blade up relay 78, wire 111 and operating solenoids 112, 113 of solenoid operated valves 60, 61 respectively to power supply line 82. The operating solenoids 112, 113, like the solenoids 93, 94, are in parallel circuit, and their energization actuates the respective valves 60, 61 with which they are associated to connect the lower ends of the cylinders 47, 48 to the pressure fluid supply line 6Z`and the upper ends of the cylinders to the reservoir or sump. The counterbalancing valves 98, 101 previously referred to are bypassed by checkvalves 114, respectively. The application of pressure fluid to the lower ends of the cylinders 47, 4S causes the blade to move in an upwardlyy direction which movement of the blade continues until the circuit for the blade up relay 78 is broken by the opening of the normally closed contacts of the up limit switch 196 carried by the frame A of the press and actuated by movement of the blade B in an upwardly direction. The cycle of operation can `be repeated by the operator again depressing the pedal 65 to reclose the pedal controlled normally open switch 67. A manual switch 115 connected between the wires 68 and 73 provides means for returning the blade to its up position in the event the shear is operated with the switch 86 open.

lt will be apparent that as a shearing operation is performed, the load or resistance to movement of the shear blade B will not be uniformly distributed'throughout the length of the blade or between the two hydraulic motorsE and F except during the performance of the cutting operation at the exact middle of the machine. 1f a relatively wide sheet is to be sheared, the cutting operation will begin at one end of the knives and progress toward the other end with the result that a greater resistance will be encountered by that end of theV movable I blade adjacent to the hydraulic motor F at the beginning of the shearing operation. This resistance encountered by the motor F will gradually decrease or be transferred to the motor E at the opposite side of the shear as the shearing operation progresses. In the operation of shears of the` character shown, it is desirable in most instances to have the movable blade B remain at a constant angle with respect to the xed blade throughout the shearing operation and the present press incorporates means for controlling the ow of pressure fluid to the respective motors in such a manner that they move at a uniform.

speed regardless of the resistance encountered.

In the embodiment of the invention shown, this mechanism, herein referred to as the blade attitude or leveling control, includes a blade attitude sensing mechanism comprising an electric bridge designated generally as I and located in the housing 118 which bridge produces a signal when the blade is out of attitude or level and an amplifying circuit for determining the polarity and magnitude of the signal and changing the flow of pressure iluid to the respective motors in accordance to the signal, to restore the blade to its predetermined angular position relative to the xed blade.

The attitude sensing mechanism shown comprises an H-shaped armature 120 made of magnetic material and having an electric coil surrounding each of the respective arms of the armature. The coils are designated 121, 122, 123, 124 and are connected to the alternating current power supply lines 68, 82 in such a manner that they form an impedance bridge of the reactor type. 'I'he coils 121-124 are llixed to the frame of the shear, in the present instance to the left-hand side housing 10, and the armature 120 is slidably supported by the housing for movement in a generally vertical direction parallel with the length of the respective arms or cores thereof. The armature120 is biased in an upwardly direction by tension spring 125 connected thereto and to a pin 126 connected to the side housing of the shear and is adapted tov be moved in a downwardly direction by a relatively non-elastic, iiexible steel band 127 connected thereto and extending in a downwardly direction from the armature, that is, in a direction opposite to the tension spring 125. From the armature 120 flexible steel band 127 passes about a sheave 130 fixed to the front of the movable blade B adjacent to the left-hand end of the blade as viewed in Fig. 1. From the sheave 130 the flexible band extends generally horizontally across the front of the blade B and passes over a sheave 1311 pivotaly connected to a member 132 on the right-hand end of the blade B which extends to the outside of the righthand side plate 11 through an elongated slot 133 in the side plate. From the sheave 131 the flexible steel band 127 extends downwardly in a generally vertical direction and has its end secured to a disk-like member 134 rotatably connected to the side housing 11 and provided with a hand grasp and means for ixedly securing it in any adjusted position. By adjusting the member 134, the armature 120 can be adjusted relative to the coils 121- 124 to balance the bridge circuit, etc.

From the foregoing it will be apparent that with the electric bridge in balance at the beginning of the shearing operation any variation or change in the attitude or level of the blade B with reference to the xed knife 40 Will cause the bridge to become unbalanced and a signal to appear across its terminals. 'I'he magnitude and polarity of the signal will be a function of the blade attitude and while this signal could be employed to effect a continuous control upon the ow of pressure fluid to the respective motors E, F at opposite ends of the blade B, in the embodiment of the invention shown the signal is applied to an amplifying circuit comprising a plurality of thyratron tubes which, in turn, interrupt the flow of pressure fluid to one or the other of the motors E, F, depending upon which end ofthe blade is leading the other.

A complete circuit is shown in the wiring diagram but will not be herein described in detail. Suce it to say that it includes means for adjusting the amount of unbalance required in the bridge circuit to fire the respective thyratron tubes 137, 138, the grid circuits of which are connected to the output or control terminals 140, 141 of the bridge. The plate circuits of the tubes 137, 138 are connected to operating solenoids 142, 143 of relays 144, 145 having normally open contacts 146, 147 in series circuit with operating solenoids 150, 1511 of normally open two- way valves 152, 153 in the pressure uid supply lines to the respective valves 60, 61 which control the actuation of the iluid pressure motors E, F respectively.

When a positive bias or signal appears on the grid circuit of the tube 137, a negative bias appears on the grid circuit of the tube 138 and vice versa; Assuming that the grid bias of tube 137 is positive and of suicient amplitude to lire the tube, relay 144 is operated to close its normally open contacts 146 and energize the solenoid 150 of valve 152 thereby actuating the valve to discontinue the ilow of pressure fluid to the valve 60 and the left-hand motor E. The signal regains control of the tube 137 after each half cycle and as long as a positive bias in excess of the predetermined'amount remains on the grid circuit of tube 137, the llow of pressure lluid to motor E will be discontinued. As soon as the other or right-hand end of the blade catches up with the left-hand end the positive bias disappears from the grid of the tube 137 and pressure fluid is again applied to both motors and the blade continues its movement until it reaches the end of the stroke. If either end ofthe blade leads the other end at any time the blade will be returned to the desired attitude'automatically. In the embodiment shown, the relay 72 previously referred to is in the nature of a safety device and is connected to the bridge circuit terminals 140, 141 in such a manner and is of such a character that in the event the out-of-attitude condition of the blade B exceeds a predetermined amount in excess of the amount required to tire the tubes 137, 138, the normally closed contacts 71 of the relay will be opened to stop the shear. Y

The safety feature imparted by the relay 72 can be omitted altogether if desired or the relay can be replaced or supplemented with some suitable alternative control, for example, the normally closed contacts 71 of the relay 72 could be replaced by a normally closed limit switch connected to the side housing 10 of the press in such a manner that its contacts would be opened by movement of the armature 120 Yin either direction in excess of a predetermined amount. 'Ihe present control is capable of extreme sensitivity to variations in blade attitude regardless of the direction in which the blade is movmg.

While in the embodiment shown an out-of-attitude condition is corrected by discontinuing the llow of pressure iuid to one or the other of the hydraulic motors, the invention contemplates as an alternative construction merely reducing the ow of pressure iluid to the leading motor as distinguished from discontinuing it entirely. In the embodiment shown, this is readily accomplished by providing the valves 152, 153 with high resistance bypasses.

The invention also contemplates as an alternative construction the use of reversible variable volume pumps 'connected directly to the hydraulic motors in a manner similar to that in which the valves 60, 61 are connected thereto and the controlling of the volume and direction of operation of the respective pumps by solenoids similar to the solenoids 93, 94, 112, 113, 150, 151. The solenoids 93, 94, 112, 113 would, for example, control the direction of operation vof the respective pumps and the solenoids 150, 151 would be used to either return the respective pumps to zero volume or to reduce the output volume, as desired.

From the lforegoing it will be apparent that the objects heretofore set forth and others have been accomplished and that a novel and improved device, such as a shear,

has been provided having a member movable by a plurality of pressure uid operated motors connected thereto at relatively widely spaced points and means for supplying pressure iiuid to the motors including an electric bridge responsive to Variations of the member from a predetermined attitude relative to a reference line for controlling the relative ow of pressure iluid to the motors to maintain a predetermined attitude. While the preferred embodiment and alternative constructions thereof have been described and referred to in considerable detail and while the bridge shown is of the reactor type, the invention is not limited to the constructions or to the type of bridge shown and it `is the intention to hereby cover all adaptations, modications and uses thereof which come within the scope of the appended claims. The term impedance as used herein includes either resistors and/ or reactors.

Having thus Vdescribed our invention wc cla-im:

l. ln a device of the character described a supporting means, a member, a plurality of pressure fluid operated motors connected to said supporting means and to said member at spaced points `for producing movement of said member relative to said support, means for supplying pressure iluid to said motors, an electric bridge including two parallel circuits each comprising a plurality of electric impedance means, means responsive to variations of said member from a predetermined attitude relative to said supporting means for varying the impedance of one of said impedance means, and means connected across said parailel circuits intermediate two of said impedance means in each circuit for controlling the supply of pressure iluid to said motors to maintain a predetermined attitude.

2. In a device of the character described a supporting means, a mem-ber, a plurality of pressure fluid operated motors connected to said supporting means and to said member at spaced points for producing movement of said member relative to said support, a source of fluid pressure, means including electric solenoid means for controlling the iiow of pressure fluid to and from said motors, an electric circuit for controlling the energization and deenergization of said solenoid means, said circuit including an electric impedance bridge means comprising two parallel circuits each including a plurality of electric reactor means, armature means forming a part of said bridge means, means operatively connected to said supporting means and to said member for varying the relative position of said armature means in response to variations of said member from a predetermined attitude relative to said supporting means, and means connected across said parallel circuits intermediate two or said impedance means in each circuit for controlling the flow of pressure iluid to said motors to maintain said predetermined attitude.

3. In a device of the character described, a supporting means, -a member, a plurality of pressure tluid operating motors connected to said supporting means and to said member at spaced points for moving said member relative to said supporting means, a source of pressure fluid, electric solenoid operated valve means for selectively connecting and disconnecting said source of pressure fluid 6 to and from said motor, an electric circuit including an electric bridge .means having two parallel circuits each comprising a plurality of electric impedance means, mov-- able control means forming a part of said bridge means for varying the impedance of Vone of said impedance means, means operatively connected to said supporting means and to said member for moving said movable control means of said electric bridge means in responseA to variations of said member from a predetermined attitude relative to said supporting means to'cause a signal or voltage to a ear across oints in said arallel circuits intermediate two of said impedances in each of said circuits the magnitude and polarity of which is a function of the variation of said member from said predetermined attitude, an amplifying circuit comprising thyratron tubes having their grid or control elements connected to said points in said parallel circuits of said bridge means intermediate two of said impedance means of each circuit such that said tubes are responsive to voltages of different polarity, and means for operatively connecting the plate circuits of said thyratron tubes to Said solenoid operated valve means for energizing and de-energizing said solenoid operated valve means to maintain said member within a predetermined attitude range relative to said lsupporting means.

4. In a device of the character described, a supporting means, a member, a plurality of pressure fluid operating motors connected to said supporting means and to said member at spaced points for moving said member relative to said supporting means, a source of pressure fluid, electric solenoid operated valve means for selectively connecting andV disconnecting said source of pressure iiuid to and `from said motor, an electriccircuit including an electric bridge means having two paralel circuits each comprising a plurality of electric impedance means, a pair of output terminals connected to said parallel circuits intermediate two of said impedances, movable control means forming a part of said bridge means for varying the impedance of one of said` impedance means, means operatively connected to said supporting means and to said member for moving said movable control means in said electric bridge means in response to variations of said member from a predetermined attitude relative to said supporting means to cause a voltage to appear across points in said parallel circuits intermediate two of said impedances in each of said circuits of said bridge means the magnitude and polarity of which is a function of the variation of said member from said predetermined attitude, an electric switching means comprising a control circuit and a controlled circuit means connecting said control circuit to said points in said parallel circuits of said bridge means intermediate two of said impedance means, and means operatively connecting said controlled circuit of said switching means to said solenoid operated valve means for energizing and de-energizing said solenoid operated valve means to maintain said member within a predetermined attitude range relative to said supporting means.

References Cited in the file of this patent UNITED STATES PATENTS 2,378,497 Phillips June 19, 1945 2,558,071 Castle et al. June 26, 1991 2,565,639 Waldie Aug. 28, 1951

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