Patent GB-1269915-A (GB)
Title: Machine tool with fluidic control system
IPC: B23Q5/26
Filed: 1970-04-15
Abstract: 1,269,915. Machine tool control. BARDONS & OLIVER Inc. 15 April, 1970 [6 May, 1969], No. 18015/70. Addition to 1,225,750. Headings B3B and B3K. [Also in Divisions F1, F2 and G4] In a machine tool having a rotatable tool holder, e.g. spindle 2, and a work-holdor, e.g. work-table 4, said holders being relatively movable to perform operation on a workpiece W, means are provided for relatively moving one-of said holders through a preselected cycle of operations, said means including a pneumatic fluidic system comprising a source of low pneumatic fluid pressure, a source of substantially higher pneumatic fluid pressure, fluid amplifier means connected to said higher pressure source and responsive to pre-selected fluidic signals from said low pressure source for controlling higher pressure pneumatic output from said fluid amplifier, indexible selector valve means connected with said low pressure source for sequential programmed distribution of a low pressure fluidic signal to effect selective work cycles, and means for indexing said selector valve means in response to movement of one of said holders. The machine tool includes a console 92 on which can be set by means of push-pull valves various function. These functions include fast traverse and cutting feed speeds for movements in the X and Y directions of a horizontal plane, and feed movements in the Z vertical direction. Each of these functions can be divided into 8, or possibly 16, sequence steps. At the end of each sequence step in the X, Y and Z directions, an indexible stop carrier is automatically indexed to select stops for the succeeding step of a machining sequence. Lights on the console 92 indicate visually the function and direction of movement. Machine tool details.-The machine tool is a vertical milling machine having spindle head 3 that is vertically movable by an hydraulic jack C1-Z. The spindle is rotated by an electric motor 12. The workpiece W is mounted on a work-tablo 4 supported by a slide 7 movable horizontally in the X direction on a slide 5 which is movable horizontally in the Y direction. Each of these movements are controlled by hydraulic jacks and the change from a traverse speed to a feed speed is achieved by actuating a restricting valve. For changing from one sequence step to the next there is provided for e.g. the X direction, and arrangement 31 that comprises an indexable shaft (34) (Figs. 7-10, not shown) having six sides which each contain adjustable stops (37) that are struck by an abutment 39 on the slide 7 at the end of a required movement. This moves the shaft axially to actuate a valve (LV-1) which initiates indexing of the shaft by a piston operated rack and pinion drive C2-X. Rotation of the shaft (34) moves an element of a selector valve S, V-1 which is coaxial with the said shaft to select the next sequence. The indexing arrangement of the shaft (34) includes a sprag clutch (48) and a spring and ball detent (49), (50). Within each sequence -movement between the stops (37) a number of machining functions can be carried under the control of a row of valves mounted in a relatively fixed portion 52 and operated by a row of adjustable trip dogs mounted in slots of a relatively movable plate 51. A similar control arrangement is provided for movement control in the Y- direction. For movement control of the spindle head 3 there is provided an indexible stop carrier that includes four adjustable stops 66 which can abut a fixed shoulder 67. The carrier is indexed by a cylinder C2-Z in a manner similar to the arrangement 31 for the X-direction movement. Fluid pressure circuit and valves.-The control circuit includes a fluid amplifier (TA) (Fig. 4, not shown) used as a relay and comprises a vented capsule a, spaced apart input and output ports b and c for low pressure, e.g. 1/30 p.s.i. to 1 p.s.i., flow. This flow can be interrupted by a low pressure supply entering through one or more ports d. A fluid amplifier (PV) (Fig. 5, not shown) comprises a vented capsule (a<SP>1</SP>) and fluid, e.g. air, at high pressure, e.g. 60-150 p.s.i. can pass through either an exhaust port (i) or an outlet port (f) depending on the presence or not of a low pressure signal at port (g) which can move a valve member (h). The selector valve SV-1 comprises a fixed element (T) (Figs. 6a, 6b, 6c, not shown) having a number of peripheral outlet ports (m-r) and an inlet port (l). An element (u) is rotated to align a radial groove (z) with one of a number of channels to connect the inlet to one of the outlets. The control circuit (Figs. 13a, 13b, 13c, not shown) indicated diagrammatically the connection of the low pressure pneumatic signals from lines (81) to (88) to the relays (TA1) to (TA14) which control the amplifier (PV1) to (PV8) to supply high pressure pneumatic fluid to control valves (OV.1) to (OV.6) that control the flow of hydraulic fluid to the jacks that move the various slides etc. of the machine tool.