US3474695A - Control for cutting presses - Google Patents

Control for cutting presses Download PDF

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Publication number
US3474695A
US3474695A US645748A US3474695DA US3474695A US 3474695 A US3474695 A US 3474695A US 645748 A US645748 A US 645748A US 3474695D A US3474695D A US 3474695DA US 3474695 A US3474695 A US 3474695A
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US
United States
Prior art keywords
solenoid
capacitor
switch
source
actuation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US645748A
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English (en)
Inventor
William B Longval
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Emhart Enterprises Corp
USM Corp
Original Assignee
USM Corp
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Filing date
Publication date
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Publication of US3474695A publication Critical patent/US3474695A/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T83/00—Cutting
    • Y10T83/869—Means to drive or to guide tool
    • Y10T83/8691—Unicyclic
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T83/00—Cutting
    • Y10T83/869—Means to drive or to guide tool
    • Y10T83/8702—Clicker die press
    • Y10T83/8704—With reciprocating presser
    • Y10T83/8716—With manually actuated control apparatus for reciprocation of presser member

Definitions

  • a hydraulic cutting press having a movable presser member and hydraulic power means for moving the member is provided with a control associated with the power means which is relatively immune to operator or component failure causing repeats and false trips of the press.
  • the control has a power means governing device actuatable to initiate a stroke and normally biased to deactuated condition, a solenoid connected to the device for operation thereof, a trip switch and a capacitor connected to the solenoid in series with the switch for supplying, when sufficiently charged, electric energy for actuation of said device in response to closure of the switch.
  • the control has a power supply connected to the solenoid for energizing it under the control of said trip switch to hold the device actuated and connected to the capacitor for charging it.
  • the power supply is inoperative to energize the solenoid sufficiently for actuation and is inoperative to charge the capacitor sufficiently for actuation while the solenoid is drawing current from the power supply.
  • the control also has a switching device for interrupting the solenoid circuit for automatic stroke termination and means for simultaneously preventing charging of the capacitor for actuation while the switching device is interrupting the solenoid circuit.
  • This invention relates to improvements in controls for hydraulic cutting presses.
  • a device governing the application of hydraulic power is solenoid operated in effecting cutting strokes of a presser member.
  • the strokes are initiated by actuation of the device in response to manual actuation of a trip switch and suitably are terminated automatically for reversal movement in response to the occurrence of a predetermined event, for example, contact between a cutting die and a conductive work support.
  • a control for causing cutting strokes of the presser member by manual actuation of a trip switch and having provision for automatic stroke termination in response to the occurrence of a predetermined event in which the hereinbeforementioned problems are obviated.
  • the control comprises a solenoid operated device for governing the power means in etfecting a cutting stroke.
  • FIG. 1 is a diagrammatic representative of apparatus embodying the present invention.
  • the illustrative apparatus comprises a press 10 of the type more completely disclosed in US. Letters Patent No. 2,821,670, granted Jan. 28, 1958 on an application in the name of Robert W. Bradley.
  • the illustrative press has a presser member 12 and hydraulic power means comprising a fluid pressure operated motor 14 for effecting movement of the presser member 12 in cutting strokes wherein the member 12 has movement of approach and separation with respect to a conductive support member 16 on which work pieces to be cut are laid.
  • Hydraulic fluid for the motor 14 is supplied from a sump 18 under pressure provided by a pump 20.
  • a control associated with the power means comprises a device for governing the hydraulic power means and operated by a solenoid 22.
  • the device includes a valve 24 having a valve spool (not shown but corresponding to the spool 28 of said patent) and relay means 26 comprising a battery 28, a valve spool operating coil 30, and normally open contacts 32 arranged in conventional relay association with the solenoid 22 for operation thereby in actuating and deactuating the device to cause movement of approach and separation respectively of the presser member.
  • the conventional arrangement of the normally open contacts 32 biases the governing device to deactuated condition for returning the member 12 to a predetermined rest position.
  • the operational relation of the solenoid with the contacts 32 provides electric operating characteristics, usual in electromagnetically operated devices such as relays, which characteristics include the requirement for a relatively higher energization for actuation for the device than for holding the device in actuated condition.
  • the solenoid may suitably be arranged if desired for direct operation of the hydraulic valve.
  • the control also comprises a manual trip switch 40 and a capacitor 42 connected to the solenoid in series with the trip switch and with a normally conducting switching device 44 whose function is described below comprising-a transistor shunted by a breakdown diode 46 protecting the transistor from possible detrimental transient voltages.
  • a source of electric energy comprises a full wave rectifier bridge 50 supplied from the secondary of a power transformer 52.
  • the negative terminal 54 of the bridge is connected directly to one pole of the capacitor 42 while the positive terminal 56 is connected to the other pole through resistors 58 and 60.
  • the source is considered as having an internal impedance which includes the series impedance provided by the resistors 68 and 60 and is connected across the capacitor and across the circuit branch comprising the solenoid and trip switch.
  • the open-circuit voltage of the source is designed to charge the capacitor 42 sufficiently for it to supply electric energy to the solenoid for actuation of the device when the trip switch is closed.
  • Sufficient series impedance is provided by means comprising the resistors 58 and 60 to render the source inoperative to so charge the capacitor when the source is loaded by an impedance having a given maximum value not exceeded by the impedance of the solenoid.
  • the series impedance is also sufiicient to limit the current drawn 'by the solenoid from the source under the aforesaid conditions to a value insuificient for actuating the device but sufiicient for holding the device actuated.
  • closure of the trip switch 40 can effect initiation of a cutting stroke only through discharge of the capacitor 42 through the solenoid 22 after the capacitor 42 has been charged from the source during an interval in which the source is not loaded by the solenoid. Therefore, a cutting stroke cannot be reinitiated by reclosure of the trip switch 40 immediately after it has been opened in terminating a cutting stroke.
  • the event may be, for example, movement of the presser member to a predetermined spacing from the support, or it may be the formation of a conductive path between the presser member and the support by penetration of the cutting die'through the work.
  • Means for deenergizing the solenoid 22 for deactuation and stroke termination in response to the occurrence of apredetermined event comprises the transistor 44 and circuit means hereinafter to be described for causing the transistor to become non-conductive in response either to the formation of a conductive path between the presser member 12 and the support member 16, or to the actuation of a limit switch 62 suitably arranged for closure of its contacts by movement of the presser member to a predetermined spacing from the support member 16.
  • a cutting stroke may be terminated by the operator releasing the trip switch 40 thereby cutting off the holding energy for the solenoid 22.
  • the charging period which desirably is brief and in the order of 100 milliseconds, begins immediately upon opening of the switch 40, it is highly unlike 1v that the operator, having voluntarily released the switch could accidentally reclose it while the presser member is returning and after a sufiicient charge has been built up n the capacitor 42 to attest actuation of the hydraulic power controlling device.
  • means are provided for preventing such charging.
  • this is accomplished by imposing on the source during the period that the transistor 44 is rendered non-conductive, a load sufiicient, i.e. having an impedance not exceeding a certain maximum value, to render the source inoperative to charge the capacitor 42 sufiiciently for actuation of the hydraulic power governing device.
  • a load sufiicient i.e. having an impedance not exceeding a certain maximum value
  • the impedance suitably consists essentially of resistance.
  • load means is integrated with the automatic stroke terminating means in a circuit which will now be described.
  • the negative terminal 54 of the bridge is connected to a negative bus 64 and, when the trip switch 40 is closed, to a negative branch conductor 66.
  • the transistor 44 is normally biased for conduction by connection of its base 67 to a voltage dividing circuit connected across the source from the junction of the resistors 58 and 60 to the branch conductor 66 and comprising a resistor 68, a resistor 70, a breakdown diode 72, and a resistor 74. A current normally flows through this dividing circuit and establishes the base 67 of the transistor 44 positive with respect to its emitter.
  • Another means for making such a connection comprises two switching devices, suitably silicon-controlled rectifiers 76 and 78 having their main electrodes connected in series between the junction of the resistors 68- and 70 and the conductor 66.
  • the aforesaid junction is slightly positive with respect to the conductor 66 because of forward voltage drop in the devices.
  • the purpose of the diode 72 is to hold off this small voltage to insure that under these circumstances there will be no forward bias on the transistor 44.
  • the SCRs 76 and 78 are controlled to be fired in response to a conductive connection between a striking plate 80 carried by the presser member 12 and insulated therefrom and a conductive portion of the work support 16.
  • the means for so firing the SCRs comprises a circuit of conventional design in which unijunction transistors 82 and 84 are connected to the gate electrodes of SCRs 76 and 78 respectively for firing them in response to the reaching of threshold emitter voltages intermediate the base 1 and base 2 voltages of the uni-junction transistors.
  • the emitter of the transistor 84 is thus normally biased at a non-firing value (assuming the switch 40 to be closed) by connection of the emitter to a voltage divider comprising resistors 90, 92, and 94 extending from a DC bus 96 regulated by a Zener diode 97 to the conductor 64.
  • a voltage divider comprising resistors 90, 92, and 94 extending from a DC bus 96 regulated by a Zener diode 97 to the conductor 64.
  • transistor 8-4 In response the transistor 8-4 conducts, pulsing the gate of SCR 78, which then conducts, energizing a time constant circuit comprising resistance means 96 and capacitance means 98 providing a variable time delay for the firing of the SCR 76 in a manner similar to that previously described for the SCR 6.
  • the voltage at the junction of the resistors 58 and 60 is reduced to a value insuflicient to charge the capacitor 42 for initiating the aforesaid governing device. If the load has been imposed by the firing of the SCRs, it will remain until the SCR circuit is opened by opening the switch 40.
  • control means associated with the power means for causing the power means to eifect such movement, said control means comprising a device for governing the operation of said power means, said device being actuatable to cause said movement of approach and being normally biased to deactuated condition to cause said movement of separation to a predetermined rest position, solenoid means connected to said device for operation thereof in actuation and deactuation, said solenoid means including at least one winding, a source of electric energy, a trip switch having contacts and manually operated means for effecting circuit closure therebetween, means for connecting said source to a wind ing of said solenoid means through said contacts of said trip switch, said source and said solenoid means being cooperative for maintaining actuation of said device during closure of said trip switch while being inoperative for the supply of sufficient current to effect actuation of the device from its deactuated state
  • control means additionally comprises means including switching means for interrupting the supply of holding current from said source to said solenoid for deactuation of said device to cause stroke termination in response to the occurrence of a predetermined event and means for preventing charging of the capacitor for actuation while the switching means is interrupting the supply of current to said solenoid.
  • Apparatus as in claim 2 in which said means for preventing charging of the capacitor for actuation comprises means for imposing a load on said source having an impedance not exceeding said given value.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
  • Relay Circuits (AREA)
US645748A 1967-06-13 1967-06-13 Control for cutting presses Expired - Lifetime US3474695A (en)

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Application Number Priority Date Filing Date Title
US64574867A 1967-06-13 1967-06-13

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2460186A1 (fr) * 1979-06-29 1981-01-23 Atom Spa Dispositif d'actionnement rapide de la tete dans des machines a decouper pourvues d'emporte-piece, particulierement de type radial
US5239202A (en) * 1990-11-30 1993-08-24 Sentrol, Inc. Failsafe interlock switch

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2821670A (en) * 1955-02-11 1958-01-28 United Shoe Machinery Corp Electronic controls for cutting machines
US3248985A (en) * 1964-05-28 1966-05-03 United Shoe Machinery Corp Stall releases for presses

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2821670A (en) * 1955-02-11 1958-01-28 United Shoe Machinery Corp Electronic controls for cutting machines
US3248985A (en) * 1964-05-28 1966-05-03 United Shoe Machinery Corp Stall releases for presses

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2460186A1 (fr) * 1979-06-29 1981-01-23 Atom Spa Dispositif d'actionnement rapide de la tete dans des machines a decouper pourvues d'emporte-piece, particulierement de type radial
US4302998A (en) * 1979-06-29 1981-12-01 Atom S.P.A. Fast operation device for the head in die-cutting machines, particularly flag type
US5239202A (en) * 1990-11-30 1993-08-24 Sentrol, Inc. Failsafe interlock switch

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GB1227553A (enrdf_load_html_response) 1971-04-07

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