Patent GB-1008102-A (GB)
Title: Improvements in or relating to the control of movable machine members
Inventor: BLAHA JOHN FRANK
IPC: B26D5/20
Filed: 1962-05-11
Abstract: 1,008,102. Guillotine cutting - machines. HARRIS - INTERTYPE CORPORATION. May 11, 1962, No. 18241/62. Heading B4B. A control apparatus for positioning the back gauge 10, Fig. 1, of a cutting-machine, at predetermined but infinitely-variable positions comprises a position control means such as a record tape 80, Fig. 3, having a plurality of signal or pulse-generating means spaced to define successive positions of the gauge, a dual speed drive means 55 to move the gauge at high and low speeds, signal sensing means 106, 107 for scanning the position control means and controlling means operatively connected to the dual speed drive means 55 for causing a change thereof from higher to lower speed operation in response to the first sensing of a signal on the position control means and to stop the drive means in response to further sensing of the same signal means, and means for causing relative movement between the position control means and the signal-sensing means through a distance at least as great as the minimum spacing between adjacent signal generating means independently of motion of the gauge. The cutting machine has a blade 20, Fig. 2, connected by links 23, and bell cranks 22 to a crank 25, mounted on a disc 27 driven by a shaft 28, from a motor 30, the shaft being driven through a single revolution during each cutting cycle by a clutch and brake mechanism 32, 34. A clamp 40 for the material to a cut is also operated during each cycle by an hydraulic motor 45, connected by links 42, 43 to the clamp. A metallic tape 65, is secured to a bracket 60, upstanding from the back gauge and is guided about a pulley 67, at the rear of the machine, a pair of guides above the clamp 40 and a pair of guide pulleys 70, and is secured to a motion-transmitting block 72. The block has a fine-adjustment connection 75 to the tape 80, which is transparent or translucent, guided over pulleys 82, the tape 65 moving the tape 80 in relation to the movement of the back gauge 10, by a two-speed motor 55. The motor 55 is controlled by signals from a pair of photo-electric cells 106, 107, which are illuminated by a light 100 and are responsive to opaque markings on the tape 80, the photocell 107, changing the speed of the motor 55 driving the back gauge from fast to slow and the photo-cell 106 stopping the motor. Each photo-cell has a control circuit including a thyratron which, when it receives an impulse, becomes momentarily positive to energize a relay L or H, Fig. 8. When the back gauge is being advanced at high speed, a relay F is energized and its contacts F1 F2 are actuated so that a high-speed coil 57 is energized and a slow-speed coil 58 is de-energized. As the opaque mark on the tape 80 passes the photo-cell 107, its relay H is energized to de-energize relay F and reverse the contacts F1, F2, so that coil 52 is de-energized and coil 58 energized to drive the motor 55 at slow speed until the mark passes the stop photo-cell 106 which actuates relay L controlling relays A and D, the latter having contacts D1 and D2 in the circuit of the motor 55 to stop the back gauge so that the material is in the desired cutting position. The motors 45 and 30, Fig. 2, are then actuated to clamp and cut the material. During the rotation of the shaft 28 driving the cutter 20, a cam 200, Fig. 8, operates a switch 202 to energize a solenoid 92 which rocks levers 85, Fig. 3, carrying the pulleys 82 for the tape 80, against a spring 95 to move the tape in the opposite direction to its normal direction of travel so that any marks that may be between the photo-cells are detected to prevent the gauge being moved at high speed when it should be driven at low speed as may be the case when a narrow piece is to be cut from the material. A further cam 205 also operates a switch 207 controlling a relay E having contacts in the supply to the relay coils L, H. At its forward position, a third photo-cell is responsive to a mark on a second track of the tape 80 to operate a relay RA which in turn controls a relay RM having contacts RM2, RM3 for effecting reverse operation of the motor 55 to return the back gauge to its rear position. The circuit also includes forward and rear limit switches 162, 163 and overriding switches 174, 175, 178 for advancing the back gauge at high or low speed and for reversing the gauge. During setting up, previous marks on the tape can be erased by a cloth tape. New marks are made on the tape at control positions by a scriber operable by a solenoid to press a carbon paper against the tape, the paper being in the form of a tape driven over rollers by a motor to present fresh paper to the scriber after each mark. In another embodiment, a magnetic tape is wrapped about a tube 212, Figs. 12 and 14, which is mounted above the back gauge 10 and is indexable to bring selected longitudinal strips in alignment with a fast-to-slow reading head 240 and a slow-to-stop reading head 242, carried by the back gauge. Each strip of the tape carries magnetic impulses corresponding to a particular cutting sequence. The heads 240, 242 are mounted on a bracket 244, supported by leaf springs 245 from an arm 60 extending from the gauge. A reverse movement reading head carried by the back gauge is disposed on the opposite side of the tube 212. A solenoid 260, which replaces the solenoid 92 shown in Fig. 8, is energized during the cutting operation to rock a lever 250 which moves the carrier 244 against a spring 255 to enable the heads 240, 242 to scan the strip and search for any signals which would necessitate slow movement of the back gauge. In a further embodiment, the tape is guided over rollers 302, Fig. 19, a sprocket 305 on the lead screw 12 of the back gauge, rollers 307, on a displaceable member 308, stationary rollers 316, and rollers 318, 320 on a ring 315 past a magnetic or photo-electric reading head 310. Movement of the member 308 acts as a fine adjustment for the tape relative to the reading head. When a signal on the tape is detected by the head to alter the speed of the back gauge from fast to slow, the ring 315 is rotated to move the rollers to the position shown dotted so that the tape is moved backwardly and then passes over the head again so that the same signal can be detected by the head to effect stopping of the back gauge, a switch 328 having been operated by movement of the ring to set the circuit for the stopping operation. During return movement of the ring after a cutting operation, the previously-sensed signal on the tape is carried beyond the reading head and any closelyfollowing signal will be detected by the head to move the gauge at slow speed. Specification 1,008,103 is referred to.