Patent GB-742658-A (GB)
Title: Apparatus for automatically locating the position of a face on a workpiece component in a machine tool
IPC: B23Q16/00
Filed: 1953-01-30
Abstract: 742,658. Machine tool details; lathes. JONES & SHIPMAN, Ltd., A. A., and HOULDSWORTH, J. Jan. 29, 1954 [Jan. 30, 1953], No. 2735/53. Class 83 (3). [Also in Group XXIII] Means for accurately positioning a workpiece, 11, Fig. 1, relatively to mechanism determining the relative axial setting of the work and cutting tool, e.g. a milling cutter, at the start of the machining operation comprises a feeler 26 coupled to the piston of a valve 3 and an operating unit 1 actuated by a pressurefluid - supply controlled by this valve for shifting the work relatively to the mechanism until the feeler is moved by a reference face 31 on the. work to interrupt the supply of fluid to the operating unit and arrest this relative shift. As described for grinding the face of the flange at the lefthand end of the work, but equally applicable to lathes, the reference face 31 is the shoulder between two sections of the work of different thickness. The work is carried between centres 10, 13, on a slidable worktable 45 which also carries the valve 3. The centre 10 is advanced or retracted by admitting fluid to the opposite ends of the unit 1, which consists of a cylinder 16 having its pistonrod formed as a rack meshing with a gear 14 in screwthreaded engagement with a sleeve 7 carrying the centre. The centre 13 is carried by a spring-urged piston 20 in a cylinder 59, being retractable by admitting fluid to the latter through a line 22. By hand actuation of the start valve 4, work supported on rests 18, 19 is picked up between the spring-urged centre 13 and retracted centre 10; the piston of the feeler valve 3 is also urged downwardly by its spring 30 to cause the feeler 26 to be positioned in the path of the shoulder 31 to set the valve for the passage of fluid (via pipes 36, 37) to a control valve 2 and the appropriate end of cylinder 16 for advancing the centre 10, exhaust from the opposite end of the cylinder being led through the valves 2, 3, via the pipes 39, 40. The valve 2 is set for this flow by the initial actuation of the start valve 4 and is held in this position against a spring 24 by a latch 25. As the centre 10 advances the work against the spring- urged centre 13, the shoulder 31 contacts the feeler and raises the piston of the valve 3 so as to cut off the pressure-and-exhaust flow therethrough and therefore bring the work to a correct position on the table. The ports in the valve 3 are constructed as described in Specification 666,996, [Group XXIX], so as to cut off the flow gradually and bring the work to rest without shock. The lower end of the valve 3 is opened to pressure through a line 32 just prior to the closing of the valve so that the piston is completely raised and withdraws the feeler from the shoulder. The table is then moved to the right for the grinding operation, the extent of this movement being determined by the usual limit-stop of the table. After grinding, the table is withdrawn, either at the will of the operator or under the influence of a signal emitted at the end of this operation, and during the withdrawal a catch 46 releases the latch 25 so that the valve 2 is positioned to cause retraction of both centres and release of the work. The start, control and feeler valves 4, 2, 3 and the operating unit 1 may be grouped as a single unit or in two or three separate units and the valves may be of rotary type. The start and control valves and tailstock-centre may also each be hand-operated. In a modification, the workhead as a whole, instead of the centre only, may be advanced and retracted by the operating unit, and, in the form shown in Fig. 6, the table 45 carrying the workhead 53 and tailstock 50 is movable longitudinally on an underslide 57 by the unit 1 (which may be fixed to the table or underslide 57), and the feeler valve 3 is held in a bracket 56 clamped at the desired position to the underslide. In a further modification, Fig. 7, the table 45 carrying the workhead and tailstock is mounted on an underslide 57, and the feeler valve 3 is carried by a bracket 66 adjustably fixed on a plate 60 slidable longitudinally on the side of the underslide under the action of the operating unit 1. The feeler valve by its coaction with the shoulder 31 sets the position of the plate 60 which carries adjustable dogs 61, 62 for controlling the subsequent traverse movement of the table 45 (with which the plate 60 then moves as one), for the grinding operation. Instead of the dogs 61, 62 co-operating with the usual control lever 65 for this purpose, a dog 69 co-operates with a stop block, or the end of the plate 60 may co-operate with an adjustablymounted stop. Specification 722,444, [Group XXIII], also is referred to.