GB783444A - Pattern-controlled machine tools - Google Patents

Abstract

783,444. Copy-milling; copy-turning. PRECISION GRINDING, Ltd. Feb. 23, 1956 [Dec. 18, 1954], No. 36674/54. Class 83 (3). A tracer-head for an hydraulically-operated lathe or milling-machine comprises a tracerspindle 7 having axial and lateral freedom of movement, a valve-member 3 which carries and is movable by the spindle and has only lateral freedom of movement, and a valve member 21 having axial freedom of movement mounted coaxially with and movable by axial or lateral movements of the spindle. The milling-machine has adjustable work and pattern-tables 38, 39 and a milling cutter 40 and a tracer 5 mounted on a slide 42 movable vertically on a slide 43 by a piston 46 controlled by the valve 21. The slide 43 is movable by a piston 50 in a cylinder 48 on a slide 49 movable similarly by a piston- and-cylinder 52, 53 under the control of the valve 3. The tracer spindle 7 carrying the tracer 5 slides on balls 11 in a sleeve 4 secured to the valve 3. The weight of the tracer spindle is partly taken by a spring 10. The valve 3 controls the flow of high-pressure liquid to four narrow ports 19 leading to two pairs of diametrically-opposite passages 14 connected to lines 57, Fig. 8, in the respective controlling means for the slides 43, 49. The valve 21, for the slide 42, is biased by a spring 33 and is actuated by the tracer 5 through a ball 36 and a thrust-piece 29 moving on balls 32. A land 28 on the valve 21 controls the flow of liquid to passages 23, 25 but allows a restricted flow at all times. In operation, low-pressure liquid is supplied both to the piston 53 to traverse the slide 49 slowly and also to one or other end of the cylinder 48, Fig. 8, through one of the pipes 64, to reciprocate the slide 43. At the end of each traverse of the slide 43, a valve is manually or mechanically operated to reverse the slide movement by supplying liquid to the other pipe 64. If, however, the valve 3 is actuated by the tracer, high-pressure liquid is supplied from a passage 14 to one of the lines 57, causing a valve 55 to move against a spring 56 and restrict the flow of low-pressure liquid from the cylinder 48; further movement of the valve 55 causes highpressure liquid to enter one end of the cylinder and override the low pressure at the opposite end. Thus, when a slope is encountered on the pattern, the valve 21 raises the cutter. If the slope is abrupt, the tracer is moved rearwardly and causes stopping or reversing of the traverse. The flow of high-pressure liquid to exhaust is controlled by adjustable valves 60 and the rest position of the valves 55 is determined by screws 61.