US3052145A

US3052145A - Stroke adjusting means mounted on cutting press swing arm

Info

Publication number: US3052145A
Application number: US735828A
Authority: US
Inventors: Muller Heinrich; Lischer Georg
Original assignee: Maschinenfabrik Moenus AG
Current assignee: Maschinenfabrik Moenus AG
Priority date: 1957-05-25
Filing date: 1958-05-16
Publication date: 1962-09-04
Anticipated expiration: 1979-09-04
Also published as: FR1206912A; DK92802C; GB880419A; DE1217020B

Description

Sept. 4, 1962 H. MULLER ET AL 3,052,145

STROKE ADJUSTING MEANS MOUNTED ON CUTTING PRESS SWING ARM Filed May 16, 1958 2 Sheets-Sheet 1 Fly 7 64 0 55\ 4L 2 e0 35 50 t 88 70 72 O i I M IIn/GWZOIS A rm RAIEYS Sept. 4, 1962 H. MULLER ET AL 3,052,145

STROKE ADJUSTING MEANS MOUNTED ON CUTTING PRESS SWING ARM 2 Sheets-Sheet 2 Filed May 16, 1958 l VIII/filial? I United States Patent Ofifice 3,052,145 Patented Sept. 4, 1962 3,052,145 STROKE ADllUSTlNG MEANS MOUNTED @N CUTTING PRESS SWENG ARM Heinrich Miiller and Georg Lischer, Frankfurt am Main, Germany, assignors to Maschinenfabrik Moenns A.G., Frankfurt am Main, Germany Filed May 16, 1958, Ser. No. 735,828 Claims priority, application Germany May 25, 1957 6 Claims. (Cl. 83-525) This invention relates to electrically controlled die cutting presses of the type which is known as clicking machines. It has particular reference to hydraulic die cutting presses in which a movable press member, for example a swing arm, is adapted to be moved over a stationary member having a table or support on which surface material, such as leather, fabric, paper or the like is spread and from which blanks are cut in the shape of a die interposed between the two press members.

Hydraulic die cutting presses of the aforesaid type are known, in which a liquid pressure medium is forced up by a pump through the hollow part of a spindle which extends throughout the height of and beyond the machine frame, and which bears a screw thread taking into a female thread at the foot of a post formed therein. By turning a hand wheel at the top of the spindle outside the machine, the swing arm which is attached to the top of a slidable hollow column, can be adjusted together with the said column in relation to the work supporting table of the machine. The pressure medium on being forced up by the pump enters a cylinder which is connected to the top of the column inside thereof and to the swing arm, causes the latter to be moved downwardly through a preadjusted stroke in order to perform the cutting operation. The swing arm is turnable about the axis of the column and can be moved across the table, into operative position over the die. In this position the machine is tripped and the material cut through, whereupon the swing arm immediately returns into its previous position of height.

A disadvantage of this type of die cutting machine is that at every stroke of the beam, or swinging arm respectively, the latter has to move through the full height of the stroke, although the actually operative part of the stroke amounts to only a fraction of it, and it is, therefore, one object of the invention to avoid the loss of time occasioned thereby and to provide a cutting press of the said type having a speedier sequence of operations resulting in a greater efficiency of the machine. Another, very important object of the invention is to enable a quick but nevertheless accurate adjustment of the cutting stroke, while a further object is to enable such adjustment to be made by more conveniently located means than has been the case hitherto.

A still further object of the invention is to minimize or even eliminate the risk of accidents to the hands of the operator, which risk has always been very great in connection with die cutting presses of this type.

With these and other objects in view the invention mainly consists in the provision of such electrical controls which enable an instantaneous begin and termination of the cutting operation, affording also a particularly effective protection against the dreaded repetitions of the cutting stroke and a simple Way of arranging he machine for either one or two hand service.

As a means of full protection against accidents the invention provides an arrangement of electrical contacts which, in case of failure of the electric controls or of the valve which regulates the flow of the pressure medium, immediately cuts off the driving current and sets the ma chine at rest.

The most essential feature, however, which allows of the aforesaid advantages being obtained, is the provision of a stroke adjusting member, preferably in the shape of a turning knob, a hand wheel or lever, which is located in a position readily accessible to the operator on the swing arm in the case of a swing arm press, so that it can be actuated by him without having to alter his position and whether the machine is at rest or at world. This knob, hand wheel or the like is attached to the outside of the swing arm on the outer end of a stud or shaft which, with its other end, extends into the swing arm and, when turned, effects the adjustment of the stroke of the swing arm along a graduated scale, so that after the aforementioned spindle has been set in the usual way to the height of the die, it can be regulated at once to any thickness of the material to be cut or to various heights of cutting dies. The turning of the knob is transmitted to a switch or contact block by means of a bevel gear or any other suitable means whereby it is moved in a definite though changeable relation to an electric cut-out switch member which is controlled by the stationary hydraulic part of the machine so as each time to cut out the circuit at the correct interval in accordance with the adjusted height of the cutting stroke.

The invention, although particularly intended for use with hydraulically operated cutting machines, can be used with the same beneficial result also in mechanically driven but electrically controlled die cutting presses. It is not limited to swing arm clicking presses, nor to any other particular type or form of cutting machine, since the inventive arrangement of the adjusting knob for operating a stroke adjusting switch or contact block is applicable also to other systems of cutting machines, such as beam presses and the like.

The accompanying drawings illustrate the invention by way of example as applied to a hydraulic swing arm cutting press, it being understood that the hydraulic means may be substituted by any other pressure applying means if required. In these drawings:

FIG. 1 is a longitudinal section through the swing arm and the upper parts of the press.

FIG. 2 represents a diagrammatic sectional view of the whole press with the swing arm, however, being shown in side elevation.

FIG. 3 shows a detail representing a modified form of the contact block.

Fitted in the lower part of the machine frame 2 and driven by an electric motor 4 is a pump 6 and normally open solenoid valve 8 which is in connection with the pump by means of a

conduit

10, 12. When the valve 8 is open, the pressure medium which hereinafter will be simply referred to as oil, flows through another conduit 14 into the oil sump at the bottom of the machine while, when the valve is closed, it enters the pressure chamber 16 at the bottom of the machine post. From here it is forced up through the hollow part 18 of a spindle 20, at the upper part of which it enters through drill holes 22 into the chamber 24 of a piston 26 which is in a fixed posi tion on the spindle MB. The bottom of the chamber 24 is formed by the bottom part 28 of a cylinder 30 which is connected to the upper part of the column 31 and to the swing arm 36 by means of a cover plate 33 or any other means. Further on the hollow spindle 20 and fixed thereto is a collar 32 having a groove 34. Into this groove takes one arm of a bell crank lever 40* which is pivoted on a pin 38 in the swing arm. The other arm of the bell crank lever bears a plate 42 the object of which will be explained at a later stage of this specification. The oil enters through the passages 22 into the cylinder 30, impinging on the piston 26 as an abutment, presses the latter downwardly by the amount of the preadjusted stroke and takes the column 31 and the swing arm 36 with it thereby pushing the die through the material on platen 37 on which, as a rule, a cutting block 39 of wood or other comparatively soft material is positioned.

So far the cutting press, with the exception of the parts 32 and 4t), complies with the generally adopted type of clicking machines which, however, is considerably improved by the novel controls and the means for the adjustment of the cutting stroke in accordance with the invention. To effect this adjustment a turning knob 44 is positioned on top of the swing arm within easy reach of the operator. When actuated, this knob turns the shaft 36 to which it is fixed and which extends into the interior of the swing arm; a scale ('FIG. 3) on the knob enables accurate setting in accordance with the thickness of the stock on the table or with varying heights of cutting dies.

Fixed to the lower end of the shaft 46 is a bevel wheel 48 which meshes with another bevel wheel 56 on a screw threaded horizontal shaft 52. This shaft is stationary on a plate 54 but movable together with the swing arm 36. When the knob 44 is turned, the spindle 52 is also turned by means of the bevel wheels 48, t} and moves a slide 56 forward or backward according to the turning direction of the knob. Adjustable on the slide 56 and fixed by a screw 58 which passes through a slot 60 is a bearing plate 62 (FIG. 3) serving as a support for the contact block 64 which consists of a switch 66 and a resiliently slidable plug 68. Normally, when the machine is at rest, the switch 66 is closed but is pushed open by the plug 68 at the end of the cutting stroke to interrupt the circuit through the solenoid valve 8. A handle 70 for swinging the arm 36 over the platen is provided at the free end of the swing arm. It is hollow and provided with contacts 72, 74 which are normally open but can be closed by the actuation of a push button 7 6 to trip the machine and cause the swing arm to descend through the stroke as adjusted by the knob 44.

The machine operates as follows:

In the position of rest the electric contacts 72, 74 in.

the handle 70 are open while the switch 66-, 68' is closed. Prior to the beginning of the cutting operation the stroke of the swing arm 36 is set by the handwheel 78. It must subsequently be adjusted to various thicknesses of material by a corresponding turn of the knob 44 in conformity with the graduations thereon. This causes the contact block 64 to move forward or backward according to the sense of rotation of the knob in relation to the plate 42 on the cut-out bell crank lever 40. The distance marked x between the contact plug 68 and the plate 42 plus the amount which the plug 68 has to be pushed in, corresponds to the length of the stroke which the swing arm 36 has to descend in order to cut through the material on the table.

Taking now hold of the handle 7% the swing arm is moved across the table and cutting

block

37, 39 and the machine is tripped by depressing the knob 76. This causes an electric circuit to be closed through the solenoid valve 8 (FIG. 2), which closes the valve and allows the oil to pass through the

conduits

10, 12, the chamber '16 and the hollow spindle 26} into the pressure chamber 24, and thereby to cause the hydraulic operation of the machine as already referred to. The swing arm on moving downwardly takes with it the bell crank lever 4a but leaves the end of its horizontal arm to remain in the groove 34 of the stationary collar 32, thus causing the lever to divert about its fulcrum 38. The cutting stroke as set by the turn of the knob 44 is ended as soon as the plate 42 on the vertical arm of the bell crank lever 40 has pushed the pin 68 sufiiciently far into the contact block as to open the switch 64. The normally closed circuit through this switch is thus interrupted and the position of the solenoid valve reversed so that the oil from the pump no longer flows into the cylinder 39 but is allowed to: escape into the oil sump via the conduit 14. A strong spring 8% serves to return the parts'fvl, 3t and 36 into their initial position.

Repeating the stroke of the swing arm in the machine just described is prevented by the installation of suitable contactors (not shown) in the c rcuit of the machine. However, should a break occur in the

switch

66, 68 or in the solenoid valve 3, which would inadvertently close the circuit when it should be open, any danger is instantaneously eliminated by the arrangement shown in FIG. 3 which immediately cuts out the current to the driving motor and sets the machine to rest. In this arrangement a second switch on with a contact plug 655a is provided side by side with the switch 66, as. This second switch is similar to the first with the exception that the contact plug is slightly shorter than the plug 68. Whereas the switch 65 is connected to the solenoid valve 8 in order to reverse the same each time at the end of a cutting stroke, the second switch 66a is connected into the circuit of the driving motor so that, when this switch becomes actuated, the circuit to the motor is interrupted at once. The machine is immediately set still with the valve 8 open and the swing arm as returning into its initial position by the action of spring 3%. It would also come to a standstill when the solenoid valve should get jammed as for instance by a break of its spring or other reason.

Actuation of the second switch 66a which, as will be understood, serves as a safety switch, becomes possible only when through a failure in the

parts

8 or 66 the adjusted stroke is exceeded and oil continues to flow into the cylinder 30. In this case the bell crank lever 40 is caused to turn through a slightly greater angle until its pressure plate 42 strikes the shorter plug 68a which cuts out the circuit through the motor and the magnetic valve and immediately stops the machine.

The

switches

66 and 66a are accessible through a hand hole 82 in the swing arm which is normally closed by a cover 84. Excessive strokes which might damage the cutting block 3?, can be obviated by a stop screw 86 on the slide 56. If the machine is to be used for thin materials only, which require but a short cutting stroke, one handle 7 ti, 7 6 will be sufiicient as no danger can accrue from such short strokes. With larger cutting strokes, however, as would be required for thick layers of material, a two-hand service is necessary to protect the hands of the operator. In this case two handles of the same or a similar type to the handle 7% must be provided and so electrically connected to another, that the circuit can only be closed when both push buttons 76 are depressed at the same time. Such two-hand operating devices are generally known and, therefore, require no detailed description. Also their electrical connections are well wit in the abilities of the expert and need not be described. It appears suflicient, therefore, to just indicated the wiring 88 in FIG. 1 for the connections between the switch and the various other electric parts.

What we claim is:

1. In a die cutting press, a machine bed, a work supporting cutting block; a vertically movable column in said machine bed, a swing arm at the upper end of said column capable of being moved over said cutting block; a die positioned on said cutting block; hydraulic drive means for moving said swing arm and said column downwardly onto the said die; electric means including a solenoid valve for controlling the movement of the swing arm; a return spring in said column for reversing the column after the termination of the cutting stroke; a manually operable member on said swing arm for adjusting the cutting stroke of same, at various preadjusted heights; elecltric means including a displaceable switch in cooperation with said manually operable member for terminating the down-ward movement of the swing arm in conformity with the setting of said manually operable member, and a bell crank lever pivotally mounted on the swing arm having one of its arms electrically connectable with the displaceable switch in the swing arm and its other arm supported on a stationary part of the machine for closing a circuit over the said solenoid valve and to thereby arrest the downward movement of the swing arm and to liberate the latter for reverse movement by the action of the said return spring.

2. A die cutting press as set forth in claim 1, in which the manually operable stroke adjusting member is a turnable knob having a graduated scale thereon.

3. In a die cutting press, a machine bed, a work support, a vertically movable hollow column in said machine bed, a stationary spindle in said column, a swing arm fitted to the upper end of said column, a striking plate to contact with a die on the work support, a hand wheel at the upper end of said spindle for setting the height of the swing arm in relation to the work support, hydraulic means including a pump for moving said hollow column and swing arm downwardly to perform the cutting stroke, electric means including a solenoid valve intermediate the pump and said column for controlling said hydraulic means; means for adjusting the stroke of the swing arm in accordance with varying cutting heights, comprising, a manually operable member on the swing arm, a movable electric switch in connection with the electric means for opening the solenoid valve to arrest the downward movement of the swing arm, a pivoted contact member on the swing arm intermediate said switch and said stationary spindle of the press; and means intermediate the said manually operable member and said switch for moving said switch so as to close contact at that height of the swing arm above the work support which has been preadjusted by the said manually operable member, said pivoted contact member when actuated engaging the electrical switch to open said solenoid valve and to allow for the return of the swing arm into its initial position.

4. In a die cutting press, a machine bed, a work supporting cutting block, a vertically movable column in said machine bed, a swing arm at the upper end of said column capable of being swung over said cutting block, hydraulic drive means for moving said column and swing arm downwardly onto said cutting block; an electric working circuit including a solenoid valve for controlling said hydraulic means; means for arresting the downward movement of the said swing arm at various preadjusted heights, comprising, a turnable knob mounted on the exterior of the swing arm, a displaceable switch block on the swing arm, means intermediate said turning knob and said switch block for moving the latter in accordance with the turning of the said kno b, a resilient contact plug in the working circuit protruding from said switch block, a bell crank lever pivoted to the said swing arm and having one arm disposed at a variable distance opposite the said plug and its other arm supported on a stationary part of the press to cut out the working circuit when contact is established between said plug and said bell crank lever upon downward movement of the swing arm.

5. In an electrically controlled die cutting press as set forth in claim 4, a gear wheel at the lower end of the knob, a screw threaded spindle on which the said switch block with its contact plug is displaceably mounted, and gear means in cooperation with the said gear wheel for transmitting the movement of said knob to the said screw threaded spindle so as to displace the said switch block in relation to the adjacent arm of said bell crank lever.

6. In an electrically controlled die cutting press as set forth in claim 4, said hydraulic means including a pumping circuit; a twin switch block within said swing arm, comprising, a contact plug in the working circuit, a second contact plug in the pumping circuit and of slightly shorter length than the first-named plug, a contact plate on the bell crank lever arm opposite the said switch extending over both plugs so as normally to contact with only the longer plug but to additionally also contact the second shorter plug upon failure of the first.

References Cited in the file of this patent UNITED STATES PATENTS 2,356,790 Home Aug. 29, 1944 2,360,070 Meyer-bach Oct. 10, 1944 2,416,055 Johndrew Feb. 18, 1947 2,818,798 Deykin Jan. 7, 1958 2,818,922 Stratton Jan. 7, 1958 2,827,765 Towler Mar. 25, 1958 2,832,196 Lindsey Apr. 29, 1958 FOREIGN PATENTS 663,408 France Nov. 3, 1928