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

Claim 2

A control system for operating presses and the like of the type having a path for insertion and removal of work pieces, comprising: a motor operated protective shutter moveable into and out of said work piece insertion and removal path; a light curtain incorporating a photocell device and defining a light controlled area transversely in said path and on the operator''s 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 means actuable by said shutter upon such closure thereof; press releasing circuit means responsive to said actuation of said shutter contact means for starting said press; 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; and further timing means in circuit with said press releasing circuit means for timing a period during which press operation must be initiated.

Claim 3

Control system as claimed in claim 1, in which said 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 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.

Claim 4

A control system for operating presses and the like of the type having a path along which work pieces are insertable and removable by an operator, comprising: a motor operated protective shutter moveable for blocking and unblocking the work piece insertion and removal path; light curtain means disposed transversely of said path and on the operator''s side of said shutter and including photocell means responsive to objects inserted through the light curtain; 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.

Claim 5

A control system for operating presses and the like of the type having a path along which work pieces are insertable and removable by an operator, comprising: a motor operated protective shutter moveable for blocking and unblocking the work piece insertion and removal path; light curtain means disposed transversely of said path and on the operator''s side of said shutter and including photocell means responsive to objects inserted through the light curtain; 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.

Claim 6

Control system as claimed in claim 3 in which 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 (1) 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.

Claim 7

Control system as claimed in claim 3 in which 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.

Claim 8

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.

Claim 9

Control system as claimed in claim 6 in which 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.

Claim 10

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.

Claim 11

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.

Claim 12

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.

Claim 13

Control system as claimed in claim 10 in which 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.