Patent GB-240185-A (GB)
Title: Improvements in machines for cutting toothed gears, screw threads and the like
IPC: B23F5/20
Filed: 1925-09-21
Abstract: 240,185. Gribojedoff, N. von. Sept. 20, 1924, [Convention date]. Gear-cutting ; milling screws; milling-cutters.- In a machine for automatically cutting spur or bevel gears of either straight or spiral type, and applicable also to cutting screw threads, the tools are pivoted to a rotary disc and are automatically moved successively into working position by means of cam-mechanism. A number of toolheads may be incorporated. In Fig. 1, which shows a machine having two tool-heads, the frame 21 carries a main shaft 22 which through spur gearing 24 drives a shaft 29 carrying worms 31 driving worm wheels 32 which support either directly, as shown, or through a separate disc, the pivoted tool-holders 36 carrying cutters 38. The shaft 22 also drives through worm gearing 25, the vertical work spindle 27 carrying a bevel gear blank 28. The tools are forced up to the work by means of a cam 40 which is shaped to give either a straight or curved cutting stroke and is loosely supported on the shaft 41. The cam 40 is controlled by a second cam 42 loose on the shaft 41 and secured to a ratchet wheel 43. The rotation of the cam 42 is normally prevented by pawls 44 pivoted to a fixed disc 46. A driving pawl 48 is carried in a pivoted holder 47 and during the revolution of the tool heads 32, projections 54 carried by the worm wheel 32 actuate the pawl holder 47 to rotate the.cam 42 through one tooth of the ratchet wheel. The motion of the cam 42 transmits a fine feed movement to the cam 40 through a lever 58, the feed being so arranged that very light finishing cuts are taken on the blank at the end of the operation. In order to vary the tooth form, cross movements may be imparted to the cutting-edge by mounting the holders on spherical members 65, Fig. 5, secured to the tool-head 32. Other means for imparting cross movements to the tools are described. This cross movement may be performed automatically by means of profiled discs secured to the cam 40. In some cases the cross movement mav be arranged to produce teeth with longitudinally varying cross section such as bevel wheels. If the work is stationary, straighttoothed wheels or grooves in shafts may be cut, but for cutting spiral or other curved teeth or screw threads, the work and tool-heads are rotated simultaneously. In a modification, Fig. 15, two work pieces 28, 28<1> may be machined simultaneously. In a further modification, Figs. 10 and 11, for cutting four teeth on a blank simultaneously the machine is driven from an electromotor 73 and the four tool-heads are mounted on a table 85 driven through bevel gearing 77, 80. A wheel 26 which operates the toolheads is driven by a second bevel pair 78, 81 while the work spindle is driven by the bevel gears 79, 82. The three motions may be operated independently. In a further modification, Fig. 12, a triangular frame 87 is provided with rotary tool discs 90 driven from a worm 92. A number of tool frames such as 87 may be arranged on a rotarv table 85 as shown in Fig. 14. The cutters 38 may be of circular shape and provided with several cutting edges or, instead of cutting tools, grinding tools may be employed. Reference has been directed by the Comptroller to Specification 106,520.