Safety apparatus for a punch press

Claim 2

Safety apparatus attachable to a punch press which includes a flywheel, an electric drive motor which drives the flywheel, and a triggering device for initiating the pressing cycle, the flywheel being engageable with a crankshaft by means of a selectively engageable clutch for driving a ram, said safety apparatus comprising: a. a drive and braking motor, said motor driving in one direction when power is supplied to the motor and imparting a braking force in a direction counter to the driving direction when the power supply to the motor is shut off; b. means operably connecting said drive-brake motor to the flywheel on the punch press for driving and braking the motion of the flywheel; c. starting switch means movable between an open and a closed position for intermittently transmitting power from a power source therethrough; d. starting switch actuation means responsive to activation of the triggering device operably connected with the triggering device and with said starting switch means for moving said starting switch means between an open and a closed position when the triggering device is activated; e. an energizable timing switch operably connected with said starting switch means so as to become energized when the starting switch means are actuated, said timing switch having a time delay which is initiated when said timing switch is energized, said timing switch being automatically movable between an opened and a closed position at the end of the time delay; f. circuit means operably connecting the drive-brake motor with the starting switch means and a power source, for starting the motor when the starting switch means are actuated; g. engagement means operably connected to said timing switch for positively engaging the clutch which interconnects the flywheel with the crankshaft, said engagement means movable from a disengaged to an engaged position in response to the switching of said timing switch at the end of the time delay to thereby allow the flywheel to move the crankshaft through a pressing cycle; and h. shut-off switching means operably attached to the crankshaft and said circuit means for shutting off power to said drive-brake motor after one pressing stroke of the ram has been completed, thereby causing said drive-brake motor to brake the motion of the flywheel to which it is connected.

Claim 3

The safety apparatus of claim 1 wherein: a. said starting switch actuation means include a safety shield movable from an open position wherein a work area beneath the press ram is generally accessible, to a closed shielding position wherein the work area beneath the ram is generally inaccessible, said shield movable from the open to the closed position in response to activation of the triggering device; and b. said starting switch means include a starting switch movable from an open to a closed position in response to movement of said safety shield from its open to its closed position.

Claim 4

The safety apparatus of claim 2 wherein said engagement means include: a. an electronically controlled valve for selectively passing fluid pressure from a fluid pressure source, said valve movable between an open and a closed position in response to the switching of said timing switch at the end of the time delay; b. a fluid piston having a movable ram which is moved by fluid pressure channelled to said piston from said electronic valve in response to movement of said electronic valve between an open and a closed position; c. fluid supply means for supplying fluid pressure to said fluid piston from said electronic valve; and d. linkage means connecting said fluid piston ram to a clutch to move the clutch from a disengaged to an engaged position when said fluid piston ram is moved in response to the opening and closing of said electronic valve.

Claim 5

The safety apparatus of claim 1 wherein said shut-off switching means include: a. a shut-off switch positionable adjacent a press crankshaft and having a movable contact element, said shut-off switch movable between an open and closed position when said contact element is moved; b. a cam connectable to a crankshaft to rotate therewith, said cam having an uneven exterior contour with an extended actuating portion and being connected to the crankshaft generally adjacent said shut-off switch such that the actuator portion of the cam activates said shut-off switch when the crankshaft has moved a press ram to complete a pressing cycle; and c. circuit means interconnecting said shut-off switch and said drive-brake motor to shut off power to the motor when said shut-off switch is moved between an open and a closed position thereby braking movement of a flywheel which may be operably connected to said drive-brake motor.

Claim 6

The safety apparatus of claim 1 wherein said timing switch includes means for selectively varying the time delay of the timing switch.

Claim 7

The safety apparatus of claim 4 wherein: a. said starting switch is a magnetic switch movable between an open and closed position in response to the movement of a metallic member thereby; and b. said safety shield contains a metallic member to actuate said magnetic starting switch when said safety shield moves between its open and closed position.

Claim 8

A punch press with safety apparatus for stopping and starting a press flywheel at each pressing cycle, said punch press comprising: a. drive motor having braking means to brake the motor when power to it is cut off; b. a flywheel; c. flywheel connecting means for operably connecting said drive motor to said flywheel to rotate the flywheel when said drive motor is powered and to brake the motion of the flywheel when power is cut off to said motor; d. a crankshaft in combination with a ram, said crankshaft being engageable with the flywheel, and acting to drive the ram through a pressing cycle once said crankshaft is turned through one revolution; e. a selectively engageable clutch for engaging said flywheel with said crankshaft; f. a triggering device for initiating the pressing cycle of said crankshaft; g. starting switch means movable between an open and a closed position wherein power may be transmitted from a power source therethrough; h. starting switch actuation means responsive to activation of said triggering device operably connected with the triggering device and with said starting switch means for moving said starting switch means between an open and a closed position when said triggering device is activated; i. an energizable timing switch operably connected with said starting switch means so as to become energized when the starting switch means are actuated, said timing switch having a time delay which is initiated when said timing switch is energized, said timing switch being automatically movable between an open and a closed position at the end of the time delay; j. circuit means operably connecting at least said drive motor and said starting switch means with the power source for starting the drive motor as the timing switch is energized by actuation of the starting switch means; k. engagement means operably connected to said timing switch for positively engaging said clutch, said engagement means being movable from a disengaged to an engaged position in response to the switching of said timing switch at the end of the time delay to thereby allow the flywheel to move the press through a pressing cycle; and l. shut-off switching means operably attached to said crankshaft and said circuit means for shutting off power to said drive motor after one pressing stroke of the ram has been completed, thereby braking the motion of said flywheel.

Claim 9

A punch press with safety apparatus for stopping and starting a press flywheel at each pressing cycle, said punch press comprising: a. drive motor having braking means to brake the motor when power to it is cut off; b. a flywheel; c. flywheel connecting means for operably connecting said drive motor to said flywheel to rotate the flywheel when said drive motor is powered and to brake the motion of the flywheel when power is cut off to said motor; d. a crankshaft in combination with a ram, said crankshaft being engageable with the flywheel, and acting to drive the ram through a pressing cycle once said crankshaft is turned through one revolution; e. a selectively engageable clutch for engaging said flywheel with said crankshaft; f. a triggering device for initiating the pressing cycle of said crankshaft; g. starting switch means movable between an open and a closed position wherein power may be transmitted from a power source therethrough; h. starting switch actuation means responsive to activation of said triggering device operably connected with the triggering device and with said starting switch means for moving said starting switch means between an open and a closed position when said triggering device is activated; i. an energizable timing switch operably connected with said starting switch means so as to become energized when the starting switch means are actuated, said timing switch having a time delay which is initiated when said timing switch is energized, said timing switch being automatically movable between an open and a closed position at the end of the time delay; j. circuit means operably connecting at least said drive motor and said starting switch means with the power source for starting the drive motor as the timing switch is energized by actuation of the starting switch means; k. engagement means operably connected to said timing switch for positively engaging said clutch, said engagement means being movable from a disengaged to an engaged position in response to the switching of said timing switch at the end of the time delay to thereby allow the flywheel to move the press through a pressing cycle; and l. shut-off switching means operably attached to said crankshaft and said circuit means for shutting off power to said drive motor after one pressing stroke of the ram has been completed, thereby braking the motion of said flywheel.

Claim 10

The punch press of claim 7 wherein a. said starting switch actuation means include a safety shield movable from an open position wherein the work area beneath the ram is generally accessible, to a closed shielding position wherein the work area beneath the ram is generally inaccessible, said shield movable from the open to the closed position in response to activation of said triggering device; and b. said starting switch means include a starting switch movable from an open to a closed position in response to movement of said safety shield from its open to its closed position.

Claim 11

The punch press of claim 8 wherein said engagement means include: a. an electronically controlled valve for selectively passing fluid pressure from a fluid pressure source, said valve movable between an open and a closed position in response to the switching of said timing switch at the end of the time delay; b. a fluid piston having a movable ram which is moved by fluid pressure channelled to said piston from said electronic valve in response to movement of said electronic valve between an open and a closed position; c. fluid supply means for supplying fluid pressure to said fluid piston from said electronic valve; and d. linkage means connecting said fluid piston ram to said clutch to move the clutch from a disengaged to an engaged position when said fluid piston ram is moved in response to the opening and closing of said electronic valve.

Claim 12

The punch press of claim 7 wherein said shut-off switching means include: a. a shut-off switch positionable adjacent said crankshaft and having a movable contact element, said shut-off switch movable between an open and a closed position when said contact element is moved; b. a cam connected to said crankshaft to rotate therewith, said cam having an uneven exterior contour with an extended actuating portion and being connected to the crankshaft generally adjacent said shut-off switch such that the actuator portion of the cam activates the shut-off switch when the crankshaft has moved the press ram to complete a pressing cycle; and c. circuit means interconnecting said shut-off switch and said drive-brake motor to shut off power to the motor when said shut-off switch is moved between an open and a closed position thereby braking movement of said flywheel.