Patent GB-641591-A (GB)
Title: Profiling machine
Inventor: KESTELL THOMAS AUBREY
IPC: B24B17/02
Filed: 1944-01-27
Abstract: 641,591. Profiling turbine blades. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. Jan. 27, 1944, No. 1583. [Class 83 (iii)] [Also in Group XXIII] In the grinding, turning or milling of articles of irregular contour, for example turbine blades, the work is mounted for rotation about an axis placed eccentrically in a sleeve, which is oscillated about its axis by a cam, and is also traversed axially to carry the work past the grinding-wheel &c. The work, shown as turbine blades 6, Fig. 9, is mounted on a holder 1 mounted in one end of shaft 9 placed eccentrically in a sleeve 10 rotatably and slidably carried by a body casting or head 3, Fig. 1, and oscillation of the sleeve is effected by an arm 15 rigid with the sleeve and carrying a roll pressed by a spring 16 to engage a barrel cam 14. The shaft 9 is driven by a pinion 18 engaging internal teeth on a ring 25, which also has external teeth engaged by a gear 4 on a shaft 17 ; by the use of change gearing 37, 184, 186, 187, the work may be driven at the required speed in relation to that of the cam 14. When two workpieces are mounted on the holder, the cam 14 may be rotated at twice the speed of the work shaft 9. The work is traversed past the grinding wheel 7 by axial movement of the sleeve 10, the movement being effected by a lever 26 pivoted to the head 3 and carrying a roll 27 engaging a slot 28 in the sleeve 10, and a roll 30 engaging a track 91 in a rotating cam 92. At the end of each traverse the head 3 is fed transversely to apply additional cut, this feed being effected by a screwed shaft 108 journalled in the head 3 and engaging a fixed threaded brush 109, Fig. 5, the shaft being rotated step-by-step by a ratchet wheel 106 connected to the shaft through a friction clutch 111, 112 and actuated by pawls 103, 104, on a lever 98, pivoted at 108 and carrying a roll 107 engaging a cam 102, Fig. 6, mounted to rotate with the cam 92 ; the amount of feed is adjusted by a stop comprising an eccentric 97 engaged by the lever 98 and rotatable by a .handle 94, and handoperated feed may be applied by means of a handle 234 on the shaft 108. A stop device to prevent further feed after the work has been ground to finished size is provided, comprising a stop 118 formed as a hollow, spring-pressed plunger mounted in the slide 119 for the head and clamped by an eccentric 120 ; the stop engages an adjustable screw 121 carried by the head 3 when the work is to size. The grinding- wheel is mounted on a compound slide and can be moved to engage a fixed dressing-diamond, so that after dressing the working face of the wheel occupies a constant position relative to the fixed stop 118. The shaft 9 is mounted in the sleeve 10 in a double conical bush 124 at its forward end, and at its rear end by a sleeve in a bush, a spring, or nuts on the shaft preventing axial movement. In order to prevent slack in the traverse mechanism, when grinding the end faces of the work, a spring pressed plunger engaging an abutment is mounted in the head 3. A steady device is provided comprising a centre 141 engaging the end of the holder 1 and carried by a bracket 140 mounted by means of a bracket 139 secured to the sleeve 10, the bracket 140 acts as a trough to catch cutting lubricant, which drains away through a pipe 89. When blades with a thin trailing edge are to be ground &c. a device for preventing lifting of the edge is provided comprising a disc 150, which contacts the work just in advance of the grinding wheel and is carried by a lever 153, Fig. 10, connected by a rod 158 to a lever 160, Fig. 11, acted on by a spring 163 ; the disc 150 is lifted as the grinding wheel reaches the root shoulder of the work by a cable 166 connected to the lever 160 and to a lever 174, which is moved by a projection 181 on the feed cam 102. In a modification, for grinding the concave face of turbine blades &c. an internal grinding wheel, Fig. 14, is used ; the arm 15 is replaced by a vertical arm. In a further modification, the gear 38 has two sets of external teeth meshing respectively with pinions carried by the cam-shaft and by a sleeve rotatable thereon, the cam having engagement, by means of dowel pins with either the shaft or the sleeve, according to the gear ratio required. For cutting operations other than grinding, the appropriate tool is employed ; Fig. 20 illustrates the use of a turning tool 231, whilst for internal operations, a boring bar would be used. Specification 641,592 is referred to.