GB1001864A - Improvements in and relating to machine tools - Google Patents

Abstract

1,001,864. Fluid pressure apparatus. MIDDESEX TOOL & GAUGE CO. Ltd. May 16, 1962 [March 24, 1961], No. 10870/61. Heading F1P. [Also in Division B3] Control means for reducing the rate of feed of a rotary tool holder which is axially moved by fluid pressure in a spindle head of a machine tool comprises, rod means located parallel to the axis of the tool holder and quill 13 which is adapted to actuate switches which control the fluid pressure circuit during the axial movement of the tool holder. The pressure circuit may be pneumatic, hydraulic or a combination of both. In the case of the former, shown in Fig. 5, the closing of the switch 49 actuates solenoid 52 which operates the valve 53 to permit compressed air to move the pistons 21 and 30 to the right which at the same time facilitates the expulsion of air from cylinder 32 via lines 57 and adjustable restrictor valve 59 and the open valve 60. At a predetermined part in the forward movement of the tool holder and quill switch 48 is closed which actuates solenoid 61 to close valve 60 and thereafter air is only allowed to pass through the restrictor valve 59. In consequence of this pressure builds up in the cylinder 32 and the rate of feed of the tool holder is slowed down to a predetermined value. At the end of. the feed movement a microswitch 70 is actuated which operates solenoid 71 to reverse valve 53 so that the spaces behind the piston 21 and 30 are connected to exhaust channel 72. The air supply is now connected to the line 73 and through a non return valve 74 to line 57 and into cylinder 32 to effect the return of the tool holder and quill to their initial position. In the embodiment shown in Fig. 6 the pressure system is a combination of pneumatic and hydraulic pressure in which air pressure is adapted to act upon an hydraulic fluid, e.g. oil, in reservoirs 81 and 89 which are connected to feed and return cylinders respectively. The operating switches 91, 77 and 95 being the equivalent to switches 48, 49 and 70 in the pneumatic circuit. Specification 1,001,865 is referred to.