US3208324A

US3208324A - Die cutting press with control means for varying the up stroke

Info

Publication number: US3208324A
Application number: US309779A
Authority: US
Inventors: Salway-Waller Malcolm
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1962-10-02
Filing date: 1963-09-18
Publication date: 1965-09-28
Anticipated expiration: 1982-09-28
Also published as: DE1435312A1

Description

Sept 8, 165 M. SALWAY-WALLER 3,208,324

DIE CUTTING PRESS WITH CONTROL MEANS FOR VARYING THE UP STROKE Filed Sept 18, 1963 2 Sheets-Sheet l Inventor Malcolm SaZway-[Valler B hzs Attarne DIE CUTTING PRESS WITH CONTROL MEANS FOR VARYING THE UP STROKE Filed Sept. 18, 1963 Sept. 28, 1965 M. SALWAY-WALLER 2 Sheets-Sheet 2 NE F E H I NQN/ J m o N 3 #8 $0: T H W1 W E K H N3 .3 Q J W L B g 33% T 3 g b T 5 Sb mfiiw wk 3% 3% Q 1% m Xx N&\ w T w NQ w) m\ E W A .1 a: *5

United States Patent O 3,208,324 DIE CUTTING PRESS WITH CONTROL MEANS FOR VARYENG THE UP STROKE Malcolm Salway-Waller, Leicester, England, assignor to United Shoe Machinery Corporation, Boston, Mass, a corporation of New Jersey Filed Sept. 18, 1963, Ser. No. 309,779 Claims priority, application Great Britain, Oct. 2, 1962, 37,261/62 5 Claims. (Cl. 83-527) This invention relates to improvements in die cutting presses and more particularly to improvements in control means for hydraulically operated die cutting presses for governing the cutting stroke thereof, that is, the movement of the presser member toward and away from the cutting bed in pressing freely movable dies through work pieces thereon.

This invention is illustrated as embodied in a hydraulic die cutting press of the type commonly known to shoe manufacturers as a clicker in which the presser member is a beam swingably supported on one upright post beside the cutting bed. However, the invention is not limited to use in the illustrative machine nor to presses having the presser member mounted on a single post.

The organization of present hydraulic die cutting presses with which the present invention is concerned comprises a frame supporting a cutting bed, a presser member supported on the frame for movement toward and away from the bed, power means for effecting movement of the presser member, manual means for causing the power means to effect movement of the presser member to move it into pressing engagement with a die on a work piece supported on the cutting bed to press the die through the work piece and stroke terminating means responsive to the occurrence of a predetermined event to cause the power means to effect movement of the presser member away from the bed to return it to a rest position spaced from the cutting bed. The power means employed in such presses comprises a cylinder and piston motor connected between the frame and the presser member, generally'through a post or beam spindle on the return portion of the press stroke, the motor has been operated to drive the piston to its maximum limit of travel while adjustments of the rest position of the presser member have been provided through means for varying the mechanical connection of the presser member to the motor such as the well known hand-wheel operating on a threaded connection between the post and the motor.

For maximum productivity, this rest position desirably is that at which the presser member will just clear a die resting on the work supported on the cutting bed. Accordingly changes in die height or work thickness, or both, may change the desirable setting of the rest position.

Adjustment of the rest position by hand-wheel operation of threaded connections has proved so arduous for the operator that several attempts have been made to relieve the eifort required. Generally, however, the proposed means, such as reversible power means for operating the hand-wheel, have also incorporated considerable complexity and expense into the machine. Further, such power operated adjustment means take effect while the machine is running but not in stroke motion so that the presser member undergoes at that time movement in accordance with the adjustment which, particularly in the case of downward adjustment, may create a hazard to an operators hand.

Accordingly, it is an object of the present invention to provide simple and economical means for manually adjusting the rest position of the presser member which means will be easy to manipulate.

3,298,324 Patented Sept. 28, 11965 ice Another object of the invention is to provide in a die cutting press means for readily adjusting the rest position of the presser member which means will take effect only during the stroke cycle of the press.

To these ends and in accordance with a feature of the present invention, a die cutting press having a cutting bed, a presser member mounted for movement toward and away from the cutting bed, power means for effecting movement of the presser member and control means comprising manual means for causing the power means to effect movement of the presser member toward the cutting bed and stroke terminating means for causing the power means to terminate such movement and to effect movement of the presser member away from the bed is provided with manually adjustable time delay means for causing the power means to cease effecting movement of the presser member way from the bed a predetermined time interval after initiation of such movement.

Thus the rest position is determined by the length of the time interval, adjustment of which, suitably and as illustrated, is effected by varying a manually adjustable resistance element, does not take effect until the next ensuing stroke.

Further features and advantages of the invention will best be understood from the following description taken together with the accompanying drawings in which:

FIG. 1 is a schematic representation of the essential portions of a press embodying the invention; and

FIG. 2 is a circuit diagram of the control means for the illustrative press.

The illustrative press is a press for effecting cutting operations on sheet material such as leather, metal, paper or fabrics and comprises a frame 8 (only a portion of which is shown in FIG. 1) carrying a work supporting bed 10 and a presser member including a beam 12 between which the sheet material 20 and a freely movable cutting die 14 may be positioned. The beam 12 is fixedly secured to an upper end portion of a post 18 journalled in alignd bearings in the frame so that the beam may be swung about an upwardly extending axis at one side (e.g., the rear) of the bed so as to enable a portion of the beam to be brought opposite to a selected portion of the bed.

Power means comprising a fluid pressure operated motor is provided in the illustrative press for effecting movement of the beam towards and away from the bed and thereby to bring about relative movement of approach between the bed and the beam to cause penetration of the sheet material by a cutting edge of the cutting die so as to effect a cutting operation on the sheet material (e.g., to form a blank therefrom), and, subsequent- 1y, relative movement of separation between the bed and the beam.

For this purpose there is provided a cylinder 22 (coaxial with the post 18) in which is slidably mounted a piston 24 rigidly secured to a lower end portion of the post 18.

Ports

26 and 28 respectively communicating with upper and lower end portions of the cylinder (above and below the piston 24) are connected with a double solenoid valve V schematically represented in FIG. 1 of the drawings. Fluid is supplied to the valve V, from a sump S, by a pump P, and fluid may be returned from the valve to the sump via a pipeline 30.

The operative elements of the valve V are under the control of two solenoids SOL 1 and SOL 2.

The construction and arrangement of the valve V and the associated fluid pressure circuit are such that:

(1) when both solenoids SOL 1 and SOL 2 are de-energized the

ports

26 and 28 are in communication (via the valve V) but are isolated from the pump P and the sump S; oil circulates from the pump P to the sump S;

due to the fact that the upper and lower areas of the piston 24 are different piston displacement involves a net volume change, and since this is prevented the fluid within the cylinder 22 holds the piston at whatever level it occupied at the end of the previous operation of the machine;

(2) when both solenoids SOL 1 and SOL 2 are energized the port 26 is put in communication with the pump P while the port 28 is connected to exhaust via the pipeline 30; the beam thus descends under power at a rate predetermined by the delivery rate of the pump and the upper area of the piston 24 to effect a cutting operation on the sheet material;

(3) when SOL 2 is de-energized, SOL 1 remaining energized, the

ports

26 and 28 are connected together and fluid under pressure is supplied to both; because of the larger under surface area of the piston the piston rises (at a rate predetermined by said delivery rate and the differential area of the piston, flow of fluid taking place from above to below the piston) to raise the beam; on deenergizing SOL 1 movement of the beam ceases, the fluid pressure circuit now being in condition (1).

The solenoids SOL l and SOL 2 are included in an electric circuit which is shown diagrammatically in FIG. 2.

An A.C. supply (e.g., at 110 v.) is supplied over

lines

50, 52 while rectifiers D1 and D2 provide in

lines

54 and 56 respectively a DC. supply of the polarity indicated in FIG. 2, capacitors C1 and C2 acting as smoothing capacitors. The solenoids SOL 1 and SOL 2 are connected in

branch lines

58, 60 across the AC. supply lines and 52, the branch lines including the normally closed contacts RlA and RIB of a relay R1 and the line including (in series with SOL 2) normally closed contacts R2A of a relay R2.

The relay R1 is a two coil relay, one coil Rl-L of which is connected, through a line 62 to normally open contacts of a pair of series connected stroke-initiating switches SW1 and SW2, normally closed contacts A of which charge a capacitor C3 via a suitable resistor from the line 54. When both switches SW1 and SW2 are actuated by the operator, contacts B are closed and the charge stored in the capacitor C3 is discharged, via the line 62, through the first coil R1L of relay R1, thus closing the contacts RlA and RlB and also hold-in contacts RIC which connect a line 64 with the +D.C. line 54 thus energizing SOL 1 and SOL 2 to initiate a press stroke. The line 64 is connected, via a suitable resistor, with the second coil R1-R of the relay R1 and thus this relay is maintained in an energized condition.

The line 64 is also connected to the anode circuits of a pair of electron discharge devices, 66, 68 of the thyratron type, the anode circuit of thyratron 68 also including the operating the coil of the relay R. The thyratrons 66, 68 and their associated components together with a pressure switch PS and bottom limit switch LS provide a stroke terminating control circuit operative responsively to the occurrence of a predetermined event for causing the power means to cease effecting movement of the beam toward the bed and for causing the power means to effect return movement. This circuit is generally similar to that disclosed in United States Letters Patent No. 2,821,670 issued January 28, 1958 on an application filed February 11, 1955, in the name of Robert W. Bradley.

In the illustrative press now being described, as in the press disclosed in said patent, the beam and the bed comprise electrically conductive portions disposed opposite one another, a conductive portion on the beam being provided by a cutting plate 70 secured to, but insulated from, the beam 16, and a conductive portion on the bed being provided by an electrically conductive cutting pad 72 in intimate contact with the metallic bed which is grounded. The cutting plate '70 is connected via a suitable resistor '74 to the control grid of the thyratron 66 which is normally biased negatively with respect to its cathode by a suitable biasing circuit (including a transformer Tl, a rectifier D4, capacitor C4 and a resistor 76) as shown in the diagram, FIG. 2. The cathode is connected to the bed of the machine. The press is adapted to be used with a cutting die which provides a further electrically conductive portion which is arranged, on penetration of the sheet material by a cutting edge portion of the cutting die, electrically to bridge the gap between the electrically conductive portions (provided by the plate 70 on the beam and the cutting pad 72 on the bed) and thus to remove the bias from the thyratron 66 which thereupon fires producing a positive potential at its cathode across a resistor '78. This potential is passed, via an adjustable time delay T.D. (comprising a network of resistors and capacitors) to the control grid of the thyratron 68. This thyratron is also normally held non-conducting since its cathode is maintained at a suitable positive potential with respect to its grid by

resistors

80, 82 across the positive D.C. supply. When, after a suitable short time delay following the establishment of the circuit through the beam, the die and the bed (to insure complete cutting through of the die), the positive potential at the cathode of the thyratron 66 charges the capacitors of the time delay network sufiiciently to raise the potential of the grid of thyratron 68 to cause it to fire, the relay R2 is operated to open contacts R2A and deenergize solenoid SOL 2. Valve V is thus operated to reverse the beam, the beam rising until solenoid SOL 1 is de-energized.

Closure of the switches PS or LS shunting the tube 68 in response respectively to the occurrence of overpressure or the arrival of the beam during its movement toward the bed at a predetermined position operates directly to energize the relay R2.

The illustrative machine includes manually adjustable time delay means which is triggered responsively to the occurrence of said predetermined event by an electric signal generated at the time that reversal of the beam is initiated by the operation of relay R2 and which acts to de-energize relay R1, and hence to de-energize solenoid SOL 1 after a desired time delay interval. By adjustment of this interval during which the beam is rising, the final height of the beam above the bed will be adjusted.

- By adjustment of the time delay arrangement just referred to the operator is enabled to adjust the height of the beam above the bed to accommodate work pieces of different thicknesses.

The time delay means for adjusting the return stroke of the beam comprises a pair of thyratrons 90, 92 connected in a circuit which is basically similar to that incorporating the thyratrons 66, 68.

The anodes of the thyratrons 90, 92 are connected to a line 94 which is connected to line 62. Both thyratrons are normally biased so as to be non-conductive, the grid circuit of thyratron including a source of bias voltage (comprising a transformer T2, a rectifier D5, a capacitor C6 and a feed resistor 96). The thyratron 92 is normally held non-conductive by virtue of the fact that its cathode is at a positive potential with respect to its grid, the positive potential being provided by resistors 98, 100' in series across the negative D.C. line.

When the thyratron 68 fires to initiate a return stroke of the beam a positive pulse (constituting an electric signal generated at the time of beam reversal) is passed via a capacitor C5 and a lead 102 to the grid of the thyratron 90 which fires producing a positive voltage across a resistor 104 in its cathode circuit. The cathode is connected via a variable resistor POT 1, suitably mounted on the beam or frame for convenient manual adjustment, to a capacitor C7 shunted with a very high resistance the resistor and capacitor forming a variable time constant circuit. When the cathode potential rises C7 is charged via POT 1, and after a time interval, depending upon the setting of POT 1 the potential across C7 rises sufliciently to fire the thyratron 92 to the grid of which the capacitor is connected via a feed resistor. When thratron 92 fires, current is drawn through the coil Rl-L of relay R1 by both thyratrons 90, 92 providing equalized magnetic opposition to the coil Rl-R to permit relay R1 to drop out, thus de-energizing both solenoids SOL 1 and SOL 2 to arrest upward movement of the beam. Opening of contact RlC of relay R1 cuts off the anode supply to the various thyratrons and also isolates the operating coil of R1 from line 54. The circuit is thus reset and the press is ready for the next cutting operation. The purpose of the diode D3 is to ensure that the thyratrons 90 and 92, having fired, do not draw current from line 52 and remain in a conducting condition. The diode D6 ensures that capacitor C7 discharges rapidly, after the thyratron 90 ceases to conduct, in preparation for the next cutting operation.

If after the completion of a cutting operation the resistor POT 1 is manually adjusted, no immediate change in the height of the beam occurs. The press has first to be tripped in the usual way. On the return stroke the beam moves upwardly to the newly selected position.

The press incorporates a safety feature (like that employed in the press described in said Patent No. 2,821,670) whereby, if during descent of the beam, the striking plate contacts one hand of the operator, which hand is at a different potential from the plate, being at ground while the other hand is still grasping the controlling handle on the beam (whereby it is swung and positioned over the die by the operator), the thyratron 66 will fire initiating a return stroke of the beam. In this case the beam will rise to a position (above the point at which reversal occurred) which depends on the setting of the resistor POT 1. This feature may be used when it is desired to raise the beam to a level above that which it is occupying.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a die cutting press having a frame, a work, supporting bed carried by the frame, a presser member mounted on the frame for movement toward and away from the work supporting bed, power means operable to effect movement of said presser member toward and away from said bed, in combination therewith, control means for said power means including:

manually actuatable means for causing said power means to effect movement of the presser member toward the bed;

stroke terminating means responsive to the occurrence of a predetermined event for causing said power means to terminate the movement of the presser member toward the bed and to effect movement of the presser member away from the bed; and manually adjustable time delay means for causing the power means to cease effecting movement of the presser member away from the bed a predetermined time interval after initiation of such movement. 2. In a die cutting press having a frame, a work supporting bed carried by the frame, a presser member mounted on the frame for movement toward and away from the work supporting bed, power means including a fluid pressure operated motor for moving the presser member toward and away from said bed and means for supplying fluid under pressure to said motor, in combination therewith, control means having:

manually actuatable trip means for causing said power means to move the presser member toward the bed;

stroke terminating means responsive to the occurrence of a predetermined event for causing the power means to effect movement of the presser member away from the bed; and

manually adjustable time delay means controlled by said terminating means for causing the power means to cease effecting movement of the presser member 6 away from the bed upon the expiration of a predetermined time delay interval. 3. In a die cutting press having a frame, a work supporting bed carried by the frame, a presser member mounted on the frame for movement toward and away from the work supporting bed, power means operable to effect movement of said presser member toward and away from said bed, in combination therewith, control means for said power means including:

stroke terminating means responsive to the formation of an electric path between opposed electrically conductive portions of the presser member and bed for causing said power means to terminate the movement of the presser member toward the bed and to effect movement of the presser member away from the bed; and

manually adjustable time delay means arranged for initiation upon such reversal of the movement of the presser member for causing the power means to cease effecting movement of the presser member away from the bed after a predetermined delay interval.

4. In a die cutting press having a frame, a work supporting bed carried by the frame, a presser member mounted on the frame for movement towardand away from the work supporting bed, power means operable to effect movement of said presser member toward and away from said bed, in combination therewith, control means for said power means including:

stroke terminating means responsive to the formation of a conductive path between a cutting plate attached to said presser member and an object at a different electric potential for causing: said power means to terminate the movement of the presser member toward the bed and to move the presser member away from the bed; and

variable time delay means controlled by said stroke terminating means and arranged for initiation thereby upon such reversal of the movement of the presser member for causing the power means to cease effecting movement of the presser member away from the bed after a predetermined delay interval. 5. In a die cutting press having a frame, a work supporting bed carried by the frame, a presser member mounted on the frame for movement toward and away from the work supporting bed, power means comprising a fluid operated motor operable to effect movement of said presser member toward and away from said bed and means for supplying fluid under pressure to said member, in combination therewith, control means for said power means including:

solenoid valve means connected between said supply means and said motor and operable in governing the supply of fluid thereto for causing said power means to effect movement of the presser member toward or away from the bed or to oppose movement of the presser member in either of said directions;

manually actuatable switch means connected with said valve means for causing said power means to effect movement of the presser member toward the bed;

stroke terminating means connected to said valve means and operative in response to the occurrence of a predetermined event for operating said valve means to cause said power means to cease effecting movement of the presser member toward the bed and to effect movement of the member away from the bed; and

time delay relay means initiated responsively to the oc 7 8 currence of said predetermined event for operating manually adjustable resistance element controlling said valve means after a delay interval to cause the delay interval.

said power means to oppose further movement of the presser member, said relay means including a resistance-capacitance time constant circuit having a 5 ANDREW R. JUHASZ, Primary Examiner.

No references cited.

Claims

1. IN A DIE CUTTING PRESS HAVING A FRAME, A WORK SUPPORTING BED CARRIED BY THE FRAME, A PRESSER MEMBER MOUNTED ON THE FRAME FOR MOVEMENT TOWARD AND AWAY FROM THE WORK SUPPORTING BED, POWER MEANS OPERABLE TO EFFECT MOVEMENT OF SAID PRESSER MEMBER TOWARD AND AWAY FROM SAID BED, IN COMBINATION THEREWITH, CONTROL MEANS FOR SAID POWER MEANS INCLUDING: MANUALLY ACTUATABLE MEANS FOR CAUSSING SAID POWER MEANS TO EFFECT MOVEMENT OF THE PRESSER MEMBER TOWARD THE BED; STROKE TERMINATING MEANS RESPONSIVE TO THE OCCURRENCE OF A PREDETERMINED EVENT FOR CAUSING SAID POWER MEANS TO TERMINATE THE MOVEMENT OF THE PRESSER