Patent GB-495938-A (GB)
Title: Improvements in or relating to hydraulic broaching machine and work support therefor
IPC: B23Q5/06
Filed: 1938-03-22
Abstract: 495,938. Broaching - machines. LAPOINTE MACHINE TOOL CO., Ltd. (Lapointe Machine Tool Co.) March 22, 1938, No. 8799. [Class 83 (iii)] A hydraulic broaching- machine has electricallyoperated means controlling the movements of the broach and work support arranged so that the circuit of the control means for actuating the broach can only be closed to effect a working stroke after the work support has been moved into the correct operative position. The horizontal surface broaching machine comprises a work support C and a base carrying a cylinder 11 the piston of which is connected to the puller head 42 carrying the broach B. The hydraulic circuit, Fig. 3, comprises a variabledelivery reversible pump P supplying the cylinder 11, the pump delivery and reversal being controlled by rack and pinion gearing 32 by means of a hand lever 15 or by an automatic knock-off member 41 on the puller head coacting with collars 39, 40 on a rod 38. The rack 32 may also be actuated by a solenoidoperated valve V<1> which may be moved in either direction by energizing one of two coil circuits and is returned to neutral when both circuits are de-energized. The valve V<1> is supplied from an auxiliary pump P<2> delivering through a needle-valve 62. The work support has loading and discharge platforms 17, 18 and a supporting member 23 which may be actuated by a cylinder 20 to clamp the work W, such as an engine block, against upper abutments 19 while the surfaces 5 are broached. The work support cylinder 20 is supplied by another auxiliary pump P<1> which delivers through a needle valve 55 to a valve V which may be moved in either direction by a pair of solenoid coils. The valve V is also connected through lines 50, 51, to cross-connected locking plungers 45, 46, coacting with a block 47 on the rack 32 to lock the pump control against movement in one or other direction. The electrical interlock mechanism includes normally-open double-pole switches E.F., closed by the puller head 42 and a double-pole switch L actuated by the work clamp so that only the upper switch circuit is closed while the work is unclamped and only the lower switch circuit is closed while the work is clamped. Hand switches are provided at D, H and K and signal lights at G and R. With the machine in the loading position the parts are in the positions shown in Fig. 3. The operator first closes switch H, completing the circuit of the left-hand solenoid of valve V and shifting this valve so as to raise the work into operative position. The position of locking plungers 45, 46 and the positions of the arms of switch L are also reversed. On then closing switch D the circuit of signal G and the lefthand coil of valve V<1> are completed and valve V<1> moves to cause the pump to deliver oil to the left of cylinder 11 to effect the working stroke. This cannot occur unless the work is positioned since the lower branch of switch L is included in the solenoid circuit. When the broach head moves the switch F is broken and the light G is extinguished, the valve V<1> returning to neutral. When the working stroke is complete the knock off mechanism returns the pump P to neutral position and the switch F is closed by the broach head. The operator then closes switch K to energize the right-hand coil of valve V and reverse the connections to cylinder 20 so that the workholder is lowered and the plungers 45, 46 are returned to the Fig. 3 position. Switch D is now again closed thus completing the righthand coil circuit of valve V<1> and lighting the signal R. This actuates rack 32 to cause the pump P to return the broach and at the end of the return stroke the pump P is again neutralized and finally the switch F is closed in readiness for another cycle. No circuit can be completed unlss the broach is in one of its end positions. If the switches D and K are permanently closed the sequence of clamping, broaching, unclamping and return are performed automatically on closing the switch H.