US3911344A - Controlling system in protective devices of photocell type for presses and the like - Google Patents

Controlling system in protective devices of photocell type for presses and the like Download PDF

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Publication number
US3911344A
US3911344A US425913A US42591373A US3911344A US 3911344 A US3911344 A US 3911344A US 425913 A US425913 A US 425913A US 42591373 A US42591373 A US 42591373A US 3911344 A US3911344 A US 3911344A
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Prior art keywords
press
shutter
circuit means
contact
relay
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US425913A
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English (en)
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Lars Erik Svensson
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SAFER MARKETING AB
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SAFER MARKETING AB
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16P—SAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
    • F16P3/00—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
    • F16P3/12—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine
    • F16P3/14—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact
    • F16P3/144—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact using light grids

Definitions

  • ABSTRACT A control system for presses and the like of the type [73] Assignee: Safer Marketing Aktiebolag,
  • Circuitry responsive to the [30] Forelgn Apphcauon Pnonty Data condition of the photocell device controls operation of 1972 16833/72 the shutter motor. Press releasing circuitry, actuable to permit initiation of a press cycle, is controlled by contacts actuable by the shutter and by timing cir- [52] US. Cl. 318/480; 318/484; 317/124 Int.
  • Timing circuitry Operation of the timing circuitry is initiated Field of when the light controlled area, or light curtain, be-
  • the timing circuitry operating for a short time within which the shutter initiates and com- References Cited pletes its closing movement. Then, the press is re- UNITED STATES PATENTS lU/l97l leased for initiating a press cycle, in response to the 3 612 884 Linardosm"Hmnmmmu" 7/124 X contacts sensing the closed position of the shutter and in cooperation with the timing circuitry.
  • protective devices for presses and the like comprising a so-called light curtain, i.e. a photocell arrangement comprising a plurality of light tracks in front of the place where the working pieces are to be inserted and taken out from the press during work, as well as a protective shutter adapted to close said path of introduction and removal while the press is performing its working stroke.
  • a so-called light curtain i.e. a photocell arrangement comprising a plurality of light tracks in front of the place where the working pieces are to be inserted and taken out from the press during work
  • a protective shutter adapted to close said path of introduction and removal while the press is performing its working stroke.
  • FIGS. 1 show the system in various positions of operation, wherein:
  • FIG. 1 diagrammatically discloses the system embodying the invention in an initial operational state, wherein the protective shutter S is lifted to free the path through the light curtain L for insertion or removal of a work piece therethrough and wherein the press is in its starting position.
  • FIG. 2 is a view similar to FIG. 1 but showing the system in a subsequent state resulting from insertion of an object into the light curtain L.
  • FIG. 3 is a view similar to FIG. 2 but showing the system in a subsequent state, following removal of such object and the resultant closure of the shutter S and starting of the press.
  • FIG. 4 is a view similar to FIG. 3 but showing the system in a subsequent state wherein an object has again been inserted into the light curtain L, resulting in stopping of the press.
  • FIG. 5 is a view similar to FIG. 3 but showing the system in a subsequent state near the end of the press cycle and wherein the control circuit to the press is broken to cause the press to stop.
  • the press itself is only represented by a cam disc P driven by the press and adapted, during the operation of the press, to rotate in the direction of the arrow P.
  • the cam disc P is adapted to operate two contact means to be described later.
  • the protective device proper is represented by a light curtain device L with light beams indicated by broken lines.
  • the light curtain is provided at the path for inserting and removing work pieces in the press.
  • a protective shutter S which is movable up and down for respectively exposing and closing the said path for insertion and removal of work pieces into and from the press.
  • the protective shutter S is adapted to be driven by a linear motor having the general designation M.
  • the protective shutter S is guided in guides SG provided with cams N1, N2 and N3 adapted to cooperate with contact means G1, G2, G3 respectively.
  • the lastmentioned contact means comprise a plurality of break and make contacts and for identification of these contacts in the surrounding schematic representation, in all the Figures the first contact of for example contact means G1 is designated as G11, its second contact as G12 and its third contact as G13 and in correspondence thereto the first contact of contact means G2 as G21, the second contact as G22 etc.
  • This system of identifying the contacts is used throughout the specification also as far as contact groups belonging to relays areconcerned.
  • Two contact means G4 and G5 the contact groups of which in an analogous way can be traced in the schematic representation, cooperate with cam disc P.
  • a circuit for controlling the linear motor M adapted to drive the protective shutter 1 up and down.
  • the phase contacts of the motor are designated X, Y, Z and provided within the broken-line rectangle on the left side of the Figures.
  • the motor is such that it can operate in opposed working directions depending on the connection of its phase capacitor FC to the contacts X or Y.
  • a contact B3 is provided in a contact group belonging to a relay B to be described later on, that contact providing insertion of the phase capacitor FC between one pole of the mains and the pole clamp X while at the same time the pole clamp Y is in direct connection with the last-mentioned mains pole or vice versa.
  • Contact Z is continuously connected to the other mains pole O.
  • shutter S In the position shown in FIG. 1 shutter S is in its upper position, i.e. the linear motor pulls the shutter upwardly and the opening through the light curtain L is exposed.
  • the pole clamp X of the motor In order to reverse the driving direction of motor M it is only necessary to reverse contact B3 whereby the pole clamp X of the motor will be directly connected to the one pole of the alternating current mains via a contact K1 to be described later on, the capacitor FC being connected between said alternating current pole and the pole contact Y on the motor.
  • Three other contacts are also provided in the motor circuit viz. contacts C2 and D2 belonging to contact groups in relays C and D and a contact K2 belonging to a manual corrective button K as well as a contact G51.
  • a transformer the secondary of which feeds a rectifier circuit to form together a net unit, or dc. current supply, designated as DC.
  • Said net unit feeds relay circuits and electronic circuits with current.
  • the minus pole of net unit DC is connected to so-called protective earth, or groundT-Ewhereas the positive pole is connected to the current supply for the relay circuits.
  • a photocell amplifier circuit F which is in direct connection with the light curtain L and the contact function of which is symbolically indicated by a contact Fl.
  • relays A, B, C and D In connection with the net unit there are provided relays A, B, C and D with their contact groups designated A1, A2, A3, B1, B2 etc.
  • FIG. 1 shows a state of operation of the protective device in which the protective shutter S is lifted and the passage through the light curtain L is thus free to insert or remove one work piece therethrough.
  • the press is in the starting position as indicated by the cam disc P which is directly connected to the press.
  • control circuits for linear motor M are in such a contact position that the protective shutter 1 is held D3, resistor R3, contact A2 and contact A3. It is to be.
  • I protective shutter S cannot be lowered to closed posiin the lifted position.
  • Contact member G5 contributes thereto by its cooperation with cam P" whereby the contact thereof G51 is held in closed position and forms, as previously mentioned, a link in the motor circuit to the protective shutter.
  • the electrical signals derived therefrom being amplified in thc photocell amplifier F, thereby to obtain such a contact function that a closure is obtained through F1, whereby the circuit of relay A is closed and relay A is actuated.
  • the circuit connected to relay A comprises resistor R2 and capacitor E2 which are connected in series between plus and minus in the conductors coming from DC.
  • a holding current chain for the relays is prepared comprising contacts A1, G43, B2, D3, C3 and contacts G11, G21.
  • no holding current is obtained prior to the press being started and rotation of cam disc P to such an extent that cam P" is disengaged from contact G5 whereby contact G53 thereof will close the holding current circuit for C and D.
  • By closing relays C and D also contacts Cl and D1 are closed whereby the control circuit U of the press is closed and the press starts.
  • contact G51 will be broken which means that if for some reason the press would stop in the position illustrated in FIG.
  • capacitor E2 will be charged in this state to its full voltage by the current limiting resistor R2.
  • capacitor E1 will be charged via current limiting resistor R1 and contact A2.
  • capacitor E3 will be discharged through the circuit formed by contacts A3, resistor R3, contact D3, C3, resistor R5, contact D3, C3, resistor R5 and contact G31 to ground. This is a safety measure taken because the press shall not be operable again from its interrupted position without specific measures when the hand is removed from the light curtain.
  • relay A upon removal of hand HA from the light curtain relay A will again be actuated whereby contact A3 connects capacitor E3 with the coils of relays C and D.
  • the protective shutter S In order to get, in this position, access to and to adjust the work piece that may have come into a faulty position, the protective shutter S must be elevated to permit free passage through the light curtain. Such an operation can be performed by pressing the so-called corrective button K while simultaneously the hand HA is within the light curtain.
  • the contacts K1, K2 and K3 of the corrective button K are hereby reversed causing contact Kl to break the current to linear motor M holding the protective shutter in closed position whereas a contact K2 via the dropped relay contacts C2 and D2 connects the linear motor M to the mains in such a way that shutter S is lifted.
  • contact members G1 and G2 will be disengaged from cams N1 and N2 and subsequently contact member G3 will start cooperation with cams N3. Due to this contact reversal contacts G11 and G2] will break the connection to relays C and D thus eliminating any possibility to start the press (contacts C l and D1 connected to the supervising circuit T).
  • the reversal of contacts G12 and G22 means no change in the current flows.
  • G31 breaks the discharge current path for capacitor E3. This capacitor, however, is fully discharged under the present conditions.
  • Contact K3 now causes a current path to be established through contact A1 so that capacitor E4 is charged through current limiting resistor R4.
  • the contact positions just described are designated by dotted marks both concerning contacts and current paths. The operator now can freely handle the work piece without risk of press operation and personal injury caused thereby.
  • contact members G1 and G2 will come into cooperation with cams N1 and N2 causing, among others, contacts G11 and G21 D close. Due to the charge brought about during closing of contacts K3 in capacitor E4, there is now a direct discharge current path via diode H1 and contacts G21 and G1] to relays C and D which will be actuated and, in a way described above, cause the press to start (contacts C1 and D1 close the control circuit U of the press).
  • a particularly efficient protective system is obtained by the arrangement according to the present invention also permitting an extremely simple control of the press by the operator.
  • the construction offers, among others, the following advantages which efficiently contribute to the safety obtained with the device in question.
  • the operator In order to initiate a press movement the operator only has to pull out his hand from contact with the light curtain L whereafter the press performs a complete working stroke without further measures. If during the working stroke of the press the operator introduces his hand into the light curtain the press will be stopped but the protective shutter will remain blocked against mechanical opening due to the fact that the linear motor is connected to the mains with such a driving direction that the protective shutter S is held closed.
  • a motor operated protective shutter moveable into and out of said work piece insertion and removal a light curtain incorporating a photocell device and defining alight controlled area transversely in said path and on the operators side of said shutter;
  • shutter circuit means connected to and controlled by said photocell device for initiating operation of the shutter motor to close said shutter
  • shutter contact means actuable by said shutter upon such closure thereof
  • timing means in circuit with said shutter circuit means and actuable upon said removal of an interrupting object from said light curtain for timing a short period of time during which closure of said shutter must be initiated;
  • timing means in circuit with said press releasing circuit means for timing a period during which press operation must be initiated.
  • timing means comprises capacitors, and including relay means coupled to said photocell device and (1) disabled thereby when the light curtain is broken for causing said capacitors to be charged and (2) actuated thereby when the light curtain becomes unbroken for permitting discharge of said capacitors to said circuit shutter means so as to close the shutter, and then to said press releasing circuit means so as to start said press, said time periods being the discharge times of said capacitors.
  • a motor operated protective shutter moveable for blocking and unblocking the work piece insertion and removal path
  • contact means actuable by said shutter upon opening and closing of the shutter
  • start pulse circuit means actuable for initiating a press starting sequence in response to at least partial interruption of said light curtain by an object and responsive to a subsequent removal of the interrupting object from the light curtain for changing state, said start pulse circuit means being coupled to and actuated by said photocell means;
  • shutter control circuit means actuable in response to said change of state of said start pulse circuit means for initiating closing said shutter
  • press releasing circuit means coupled to said start pulse circuit means and contact means and responsive to closing of said shutter for simultaneously initiating the press stroke
  • timing means coupled to said shutter control circuit means and press releasing circuit means. respectively, for timing limited time intervals within which said control circuit means and press release circuit means must carry out said initiations 4.
  • said start pulse circuit means include a relay coupled to said photocell means and actuable thereby when the light curtain is unbroken and disabled thereby when the light curtain is broken, said timing means comprising capacitors, said control circuit means and press releasing circuit means including paths coupling respective said capacitors to said relay l for charging of said capacitors when said relay is disabled and, upon a subsequent actuation of said relay, (2) for enabling discharge of current from said capacitors to time said limited intervals, said shutter control circuit means and press releasing circuit means including portions coupled to respective said capacitors for actuation by the discharge current therefrom.
  • said press releasing circuit means includes a pair of relays with coils connected in parallel, said relays having contacts, a contact of one said relay being connected in series with a contact of the other said relay, the press having a press control circuit containing said series contacts and responsive to closure of both said contacts for operating said press.
  • Control system as claimed in claim 5 in which said contact means actuable by said shutter include a series pair of shutter contacts closeable and openable with said shutter, said control circuit means including a current path in which said series shutter contacts are in series with said parallel relay coils, whereby closure of both said shutter contacts is required for actuation of said relay coils.
  • said start pulse circuit means includes a relay actuable by said photocell means and having contacts, said pair of relays of said press releasing circuit means having respective further contacts in series, said press releasing circuit means further including a holding current path for said pair of relays which includes said series further contacts thereof and further includes a contact of said photocell actuable relay, said control circuit means including a further relay responsive to said photocell actuable relay for operating said shutter, means moveable in synchronism with the working stroke of the press and press stroke contacts associated therewith for completing said holding current path upon initiation of the working stroke of the press.
  • Control system as claimed in claim 7 in which said means moveable in synchronism with the working stroke of the press include a further contact, said control circuit including a current path to the shutter motor and containing said last mentioned contact for deenergizing said shutter motor upon initiation of said working stroke of said press.
  • Control system as claimed in claim 7 including means coupling a contact of said photocell actuable relay in series in said holding current path of said pair of press releasing circuit means relays for breaking said holding current path upon interruption of the light curtain following starting of the press, whereby to deenergize said pair of press releasing circuit means relays and stop said press.
  • Control system as claimed in claim 9 including a corrective contact member manually actuable after said stopping of said press and means coupling contacts of said corrective contact member in said shutter control circuit means, means defining a charging current path including a further contact of said manually actuable corrective contact member, said charging current path defining an additional start pulse circuit means responsive to deactuation of said manually actuable corrective contact member and elimination of said light curtain interruption for, simultaneously with a subsequent closing of said shutter, once again applying operating current through said series pair of shutter contacts to said parallel press releasing circuit means relays to restart the press after an interruption of press operation by an interruption of the light curtain.
  • said press releasing circuit means includes a normal press starting pulse path including a contact of said photocell responsive relay, contacts of said pair of relays of said press releasing circuit means, and a contact of said shutter actuable contact means, said normal starting pulse path being coupled to the timing means capacitor associated with said press releasing circuit means for discharging said capacitor therethrough.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Curtains And Furnishings For Windows Or Doors (AREA)
  • Operating, Guiding And Securing Of Roll- Type Closing Members (AREA)
US425913A 1972-12-21 1973-12-18 Controlling system in protective devices of photocell type for presses and the like Expired - Lifetime US3911344A (en)

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SE16838/72A SE360920B (da) 1972-12-21 1972-12-21

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DE (1) DE2363962A1 (da)
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0007420A1 (en) * 1978-07-14 1980-02-06 Erwin Sick GmbH Optik-Elektronik Safety circuit for a potentially dangerous machine monitored by light
US4467251A (en) * 1979-05-31 1984-08-21 Besam Ab Object sensing apparatus

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3612884A (en) * 1969-02-28 1971-10-12 Eastern Co Fail-safe photoelectric control system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3612884A (en) * 1969-02-28 1971-10-12 Eastern Co Fail-safe photoelectric control system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0007420A1 (en) * 1978-07-14 1980-02-06 Erwin Sick GmbH Optik-Elektronik Safety circuit for a potentially dangerous machine monitored by light
US4291359A (en) * 1978-07-14 1981-09-22 Erwin Sick Gmbh Optik-Elektronik Safety circuit for a potentially dangerous machine monitored by light
US4467251A (en) * 1979-05-31 1984-08-21 Besam Ab Object sensing apparatus
US4590410A (en) * 1979-05-31 1986-05-20 Joensson Bert Ove Object sensing apparatus

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Publication number Publication date
FI56262C (fi) 1979-12-10
DE2363962A1 (de) 1974-06-27
FI56262B (fi) 1979-08-31
SE360920B (da) 1973-10-08

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