Patent GB-520501-A (GB)
Title: Improvements in and relating to hydraulic driving mechanisms for reciprocating machine elements
IPC: B23D7/00
Filed: 1938-10-24
Abstract: 520,501. Hydraulic drives for presses &c. BOHRINGER GES., GEB. Oct. 24, 1938, No. 30728. Convention date, Oct. 22, 1937. [Class 69 (ii)] In a hydraulic drive 'for presses, planing, grinding or like machines having reciprocating tables or other elements driven with variable speed by means of. a regulatable pump, the control member of which is moved to and fro to control the direction and speed of movement of the machine element, and adjustable stops for the control member are provided for limiting the speed of the machine element, the actuation of the control member and the adjustment of the stops are effected by separate driving arrangements each comprising an electric motor. The table is connected to the driven shaft 10 of a liquid motor M which is controlled by longitudinal displacement of a rod 11. The motor M is supplied with oil through channels 14 and 15 according to the direction of rotation required, these channels being connected to a regulatable pump P controlled by longitudinal displacement of a rod 17. The latter is adjusted in either direction from a central position by means of a three-phase electric motor 34, bevel gears 33, slippage clutch 32, gears 29, 28, 27 and a control drum 21 with an interchangeable cam groove 23 which engages a roller 24 carried by the rod 17. The forward and reverse maximum speeds of the table are limited by adjustable stops 35, 36 which engage lugs 37, 38 on the drum 21. The lugs 37, 38 are carried by supports 39 which are rotated by reversible three-phase electric motors 47, 48 under the control of limit switches 49, 50. The supports may also be hand adjusted by means of keys engaging the ends 42 of the shafts 41. Should either of these auxiliary motors act against the motor' 34; the latter is automatically cut out. The shaft 22 of drum 21 also carries a cam disc 53 operating a bridge 55 between pairs of controls V, R so as to maintain the motor 34 in operation except when the rod 17 is in its central position. The motor 34 is also controlled by additional limit switches operated by lugs on the moving table. The drum 21 also carries a second cam groove 58 to engage a roller 60 on rod 11, the arrangement being such that the rod 11 is in'its lowermost position when the rod 17 is in its central position, but is moved upwards when the rod 17 is moved in either direction. Immediate arrest of the table may be effected by short-circuiting the pump P by means of rotary valves 64 in-cylindrical bores 65 in the channels .14, 15 these valves being under the control of an electromagnet 71, rudder shock being- avoided by the provision of channels 67 fitted with spring-loaded relief valves 72. Additional spring-loaded relief valves 76 are provided to prevent excessive pressure in the channels 14, 15. Suitable electrical connections are described and illustrated in the Specification. These include a pair of control boards 79, 82 each with two press-button switches 80, 81 for the auxiliary motors 47, 48 and a second pair of control boards connected in parallel and each fitted with three press-button switches, whereby the motor 34 may be operated from either of them. One of these latter press-buttons controls the electromagnet 71. Specifications 439,027, [Group XXVI], 520,524, and U.S.A. Specification 1,188,901 are referred to.