GB1032993A - A machine for cutting sheet materials - Google Patents

Abstract

1,032,993. Cutting-out presses. A. CHIESA, [trading as OFFICINA MECCANICA ARTORIGE CHIESA]. June 15, 1964 [Oct. 12, 1963; Dec. 6, 1963], No. 24717/64. Heading B4B. In a cutting-out press in which a beam 3 is moved downwardly to press a tool 6 through sheet material 5 supported by a table 2 by means of a piston 7 moving in a cylinder 8 to which hydraulic fluid is supplied, the downstroke of the beam is stopped and reversed by a control of the overpressure in the cylinder 8. The overpressure is measured and controlled by a pressure controller 34. The discharge from the cylinder 8 is controlled by a valve 15 operable by a solenoid 17. The solenoid and the pressure controller are included in an electronic circuit which comprises transistors 28 to 31, a transformer 21, 22, 25, resistances 35 to 47, flip-flops 48, 49, a stabilizer 50 and rectifiers 23, 51, 52. The beam 3 is fitted with push-buttons 32, 33. When a voltage is applied to the whole circuit transistors 30, 31 become non-conductive owing to the forced conductivity of transistor 29. To start the press, both push-buttons 32, 33 are depressed. The forced conductivity of transistor 29 is thus discontinued. At the same time, the transistors 28, 30 and 31 are made conductive, the solenoid 17 is energized and the valve 15 operated to cause the downstroke of the beam 3. At the end of the downstroke of the beam, an overpressure is built up in the hydraulic circuit which results in operation of the pressure controller to close contacts 12, 13. This causes transistor 29 to become conductive again while the transistors 30, 31 become non-conductive and the solenoid 17 is de-energized whereby the beam is stopped instantaneously and then reversed to its starting position under the action of spring 18. The above operation can be repeated after having opened, and again closed, the contacts of push-buttons 32, 33.