Patent GB-637118-A (GB)
Title: Improvements in or relating to a broaching or the like machine
IPC: B23Q5/06
Filed: 1947-06-24
Abstract: 637,118. Broaching. OILGEAR CO. June 24, 1947, No. 16642. Convention date, July 12, 1943. [Class 83 (iii)] In a broaching machine having a work carriage reciprocable by means of a crank or similar eccentric means to move the work into and out of the path of the broaching tool, the carriage engages a rigid stop just before the crank reaches dead centre and the crank is then forced into the dead centre position so that the lateral cutting reaction cannot rotate the crank and so that the carriage is pre-loaded against the lateral cutting reaction. The machine described has two alternately-operating tool-slides 7, 7a reciprocated on guides 13, 14 by hydraulic rams 11, 11a, and two work carriages 8, 8a reciprocated on guides 15, 16 by cranks 30, 30a having blocks 31 engaging slots 32 in the carriages. Each. crank-shaft is rotated by a pinion 26 engaged by a rack-bar 40 which is connected by blocks 45, 45a to pistons 42, 42a in cylinders 43, 43a. Fluid for the hydraulic cylinders is supplied by a pump 50 which may be driven by an electric motor mounted above it; the fluid flow may be reversed by means of reversing valves or by reversing the pump. The pump control may normally be towards the zero stroke position of the pump and may be controlled by two solenoids which are energized by manually-operated switches to control the direction of rotation of the pump and are deenergized by limit switches operated by the tool slides to stop the machine. Operation.-The cutting stroke of the slide connected to piston 11 is initiated by starting the pump so that fluid is delivered into line 51, Fig. 4, and thence to cylinder 43 to move the rack-bar to the right and move the work carriage 8 into operative position and the carriage 8a to the re-loading position. Just before the crank 30 reaches dead centre, the carriage 8 engages rigid adjustable stops 33, 34 but the pressure behind the piston 42 and the momentum of the moving parts continues rotation of the shaft 25 until the crank is at dead centre and the piston 42a abuts the end of the cylinder 43a. As the carriage engages the stops, port 44 is uncovered and the fluid is delivered through line 52 to force the piston 11 down. The fluid expelled from below the piston flows through line 55 to cylinder 12 and raises the piston 11a, the fluid above piston 11a being returned to the pump through line 52a, non-return valve 53a and line 51a. To raise the piston 11a quickly, a limited amount of additional fluid is supplied to the line 55 through a non-return valve 58 and a choke 56 and, at the end of the up stroke, this fluid returns to the pump through non-return valve 54a. When the piston 11 completes its down stroke, the control mechanism reduces the pump displacement to zero and the machine stops for reloading, after which the pump is reversed to deliver fluid into line 51a for a similar cycle in the reverse direction. To adjust the stroke of the rams, the valve 59 may be opened so as to supply equal pressure to both sides of the piston in the upper position and to hold it there while the pressure raises the other piston to allow for re-positioning of the limit switches. In the modification shown in Fig. 5, a valve is fitted in the lines to the tops of the cylinders and blocks the supply of fluid to the downward moving cylinder until the pressure behind the corresponding rack-bar cylinder has built up sufficiently to ensure the movement of the crank to dead centre. The pressure then opens a relief valve which releases sufficient pressure to move the valve so that there is a full flow to the top of the cylinder.