Patent GB-536544-A (GB)
Title: Method and means for finishing recesses
IPC: B21D28/22
Filed: 1940-01-29
Abstract: 536,544. Grinding. STUBBS, E., and FELLOWS GEAR SHAPER CO. Jan. 29, 1940, No. 1795. [Class 60] [Also in Group XXII] In a method of enlarging a number of recesses in a work piece, such as a series of equi-spaced holes C in a work piece W having an axis a, by planing, milling or grinding, a similar number of tools T1 ... T5, Fig. 3, of diameter less than the holes to be cut and spaced from each other and from the tool head axis b by the same respective distances as the holes, are placed so that the axes a, b of the work and tool head are separated by a distance equal to half the difference between the desired hole diameter and the tool diameter, the work and tool-head being then rotated simultaneously at equal angular velocities. The preliminary holes are made by drilling &c. In Fig. I the tools T1 ... T5 are planing tools having circular cutting edges provided with the usual axial relief, and mounted on a reciprocable spindle 20. The rotational axes of cutter and work may be inclined to each other for producing tapersided'recesses. When the lateral depth feed, Fig. 3, is applied by separating the axes a, b, the cutters cut one side of the holes to the required depth and the spindle and work holder are then rotated about their respective axes at the same angular velocity. The work is completed after one rotation of the work and tool - head; In a modification, the depth feed and rotary motions may be effected simultaneously, the rotary motions being continued for a full revolution after full depth is attained. The accuracy of the hole cutting is not affected by regrinding of the tools so long as all the tools are of the same diameter and the depth feed is suitably adjusted. In another modification, Fig. 10, holes of different diameter may be simultaneously finished. The cutting may be performed on a pinion cutter type gear shaping machine such as that described in Specification 435,702, [Group XXII]. The reciprocating spindle carrying the cutters is mounted in a saddle 23 carried on ways 24 and advanced for effecting the depth feed. The equal angular motion of the cutter spindle 20 and work spindle 22 are obtained through worm gearings 28, 29, respectively. In another modificacation notched articles such as the complementary coupling members shown in Figs. 12 and 13 may be cut. In this case a solid cutter head with the required tool elements detachably secured to its periphery or integral therewith may be employed. Thus an internal gear 41 may be cut from a preliminarily gashed blank by means of a cutter 40 having teeth narrower than the gashes. Fig. 15 shows the position after the depth feed producing separation of the axes a, b of the work and cutter has been effected. The cutter and work are then rotated through 360 degrees at the same angular speed whereupon a tooth such as T21, Fig. 15, completes first the leading tooth face p<SP>1</SP> (in the first quadrant of the motion) and then the trailing tooth face p<SP>2</SP> (in the second quadrant of motion). If the cutters are of involute form, they generate involute tooth surfaces and the outer corners of the cutters generate fillets of circular curvature. Similarly cutter heads with internal cutters may be used to generate external gear teeth. When circular holes or recesses are to be formed milling cutters or grinding wheels may be used. Such tools may be mounted in a quill 42, Fig. 17, and driven from a motor through a central gear 16. In this case the axial movement is required only to advance the tools into the work. In some cases instead of mutually inclining the cutter and work axes for cutting taper work with reciprocating cutters the lateral component for taper cutting may be given by depth feed mechanism operative during the cutting strokes.