GB709844A - Copying apparatus for use on a machine tool - Google Patents

Abstract

709,844. Copy-milling and turning. ARMSTRONG SIDDELEY MOTORS, Ltd. Jan. 1, 1953 [Jan. 2, 1952], No. 125/52. Class 83 (3) In a lathe or milling machine for copying turbine or compressor blades 27 or 27a, the need for a full-form template is obviated by providing plate templates 19 or 19a having profiles representing the blade profile at various transverse sections and spacing them correspondingly to the various sections, the individual profiles of the plate templates being faired, intermediate the spaces, by a resilient ribbon 35 on which a follower 47 or 67 bears. Lathes.-The lathe, Figs. 4 and 6, comprises a saddle 50 carrying a hydraulic cylinder 41a and a piston 86 having a rod 40a connected to the tool slide 51 and carrying a tracer valve 44a. The turbine blades 27a are mounted round a carrier 95 fitted between a headstock 53 and a centre 54 and the templates 19a, which are of circular form with lobes corresponding to the blade profile at particular sections, are mounted at one end in a chuck driven in unison with the headstock and are supported at the other end in an adjustable centre 56a. The ribbon 35 is carried by knife edges 62, 64 on the stirrups 58 of spring- loaded plungers 60, and each stirrup has a roller 59 bearing on the respective template. A crimp may be provided in the edge of the ribbon so that it is located lengthwise by one of the knife edges 64 but is still free to flex. A pump 45 supplies fluid to both faces of the piston 86 and the reaction of the ribbon on the follower 67 operates, through a bell-crank 66, a spring-loaded valve 89 connected at one side to a fluid reservoir and at the other side to the larger face of the piston 86 through a bore 87 in the piston rod, so as to give a controlled leak from the larger face. A needle valve 92 controls the speed of operation and a relief valve 83 communicates with the reservoir through a pipe 85. The saddle 50 is advanced intermittently or continuously. The templates are designed so as to compensate for the point of tangency of the rollers 59 and the templates varying with changes of curvature in the latter. Milling.-In a milling machine, Fig. 1, the tool 36 and tracer valve 44 are carried by a head 39 reciprocable by a hydraulic piston, and the plate templates 19 are mounted on compound tables 11, 13 under a bridge 29 on which spring- loaded plungers 32 are adjustably mounted, the plungers having at one end rollers 34 bearing on the templates and at the other end carrying the ribbon 35. The nose of the milling tool has the same radius as that of the rollers. The mounting of the ribbon on knife edges, and the hydraulic system, are as described above for the lathe but the tracer valve may be in a line leading directly from the hydraulic cylinder, the hollow bore in the piston rod being omitted. Chucks.-The work-pieces 27a, Fig. 4, are mounted on the cylindrical carrier 95 by being set in a lead matrix.