Patent GB-634387-A (GB)
Title: Improvements in or relating to profile generating machines
IPC: B23Q35/10
Filed: 1947-01-31
Abstract: 634,387. Grinding turbine-blades and the like. FAIREY AVIATION CO., Ltd., and LYON, G. Jan. 31, 1947, No. 3050. [Class 60] [Also in Group XXII] The profile-generating machine of Specification 633,550 is modified by mounting the tracer k and tool j for bodily rotation about circular paths on an arm 31 which is movable about an axis parallel with the axes of such circular paths, the point of contact of the tracer with the master form and the point of contact of the tool with the work being on the axes about which the tracer and the tool are rotatable bodily. The frame of the machine comprises a base 39, Fig. 4, two end pillars and a top member 41, beneath which is a guide for a traversable carriage 33 pivotally supporting about an axis 32-32 the arm 31 carrying the tool j and the tracer k which are oscillated in complete circular paths about the work and the master form respectively by a motor 94. One face of the work may be shaped before commencing the. other face by oscillating the tool and tracer mountings in semicircular paths. The tracer k is mounted on a crank disc 37, Fig. 11, secured to a shaft 79 rotatable in a member 81 which is adjustable vertically along the arm 31 within the limits of a slot, and the tool is mounted on a crank disc 38, Fig. 9, secured to a hollow shaft 99. The shafts 79, 99 are driven through worm driven from a telescopic shaft 90. The tool is rotated by a motor 111 through a belt drive 109, shaft 107, bevel gears 106, 105 and a shaft 103. Alternatively, the tool can be mounted on a spindle carried in lugs on an overhung housing and be driven by gearing from the shaft 107. The motor 94 is controlled by switches mounted on a feeler lever 136, Fig. 12, so that the tangent at the point of contact of the tool with the work is maintained parallel with the tangent at the point of contact of the tracer with the master form. The lever 136 comprises two elements pivoted together at 135, one element 134 being slidable in a transverse slot in the end of the tracer shaft and having a bifurcated end with two electric contacts 142, 143, while the other element 136 has a flat edge in contact with the master form and carries two further contacts 137, 138. A spring 139, Fig. 11, holds the straight edge of the element 136 in contact with the master form. When the lever is caused to move angularly about its pivot without a corresponding movement of the crank disc 37 a circuit is established through two of the contacts so that the motor 94 is started to rotate the mountings of the tracer and tool in the appropriate direction. The contacts may be arranged to operate the motor or an electromagnetic clutch through a gas-filled thermionic relay. To maintain contact between the tool and work, the member 31 is biassed towards its mid-position by a hydraulic cylinder 113, Fig. 8. This cylinder, together with a telescopic unit, is supported on pin joints between the lower end of the member 31 and a carriage 117 traversed by a lead screw 128 in step with the carriage 33. One element 115 of the telescopic unit is provided with two microswitches 120, 121 operated by movement of the second element 114 to displace a double acting solenoid unit 126, which governs through a selector valve 125, the flow of fluid to the cylinder. The master form a is mounted on a carriage 50, Fig. 13, which is slidable on a member 47 adjustably secured to a carriage 46 adapted to be reciprocated on a guide 44, by a motor 53, Fig. 4, through a worm drive 58, a crank disc 59 and two links 63, 66. The effective length of the link 66 may be adjustable in order to vary the stroke of the master form. The carriage 50 is engaged by a lead screw 69 driven through a set of change-gear wheels 70-73 by a ratchet wheel 74 which engages a pawl 75 on the guide 44 so that the master form is fed towards the tracer as it reciprocates. The work e is supported at one end by a centre pin carried by a hinged arm 96, Fig. 16, and at its other end by a short shaft 166 rotatably mounted in a member vertically pivoted on a block 169 which slides in guideways cut in a flange 173 on the end of a shaft 149 ; a support 148 for this shaft is mounted on a turntable which is adjustable both longitudinally and transversely by means of a known arrangement of slides. Two flexible metal bands 223, which are wrapped in opposite directions around, and secured to, the periphery of an arcuate segment 224 at one end of the shaft 149, are attached at their other ends to arms 225 which may be fixed in a range of angular positions to a cross head 220, Fig. 4, so that the straight portions of the bands are vertical. A pin on a lower cross head 220 engages a bearing block 230 slidable in a slotted lever which is pivoted on a pin 233 adapted to slide in a horizontal slot in the pillar 40. The slotted lever is oscillated by mechanism 240, 243 which is similar to that described for reciprocating the master form a and driven in synchronism therewith from the motor 53, The resultant vertical reciprocation of the cross head 220 oscillates the shaft 149 through the bands 223, and causes the work e to oscillate about the axis of the shaft 149. The segment 224 may operate the shaft 149 through a hydraulic servo-mechanism comprising, as shown in Fig. 18, a lever 258 which is integral with the segment and pivotally-connected with the operating rod 259 of a selector valve 260. This valve is mounted on the side of a hydraulic cylinder 261 which is pivoted to a lever 262 keyed on the shaft 149 and has its piston rod anchored to a lug 264 forming part of the turntable. Movements of the segment 224 are then transmitted via the hydraulic mechanism to the shaft 149. To enable work of varying pitch angle to be produced, the shaft 166 is connected by a lever 185 with a hydraulicallyloaded plunger 188, Fig. 16, bearing against a bar 189 whose angle of inclination may be adjusted on a block 200 slidable along an undercut guideway forming an integral part of the member supporting the shaft 166. The block 200 is connected with the carriage 33 by a rod 214 and to enable it to participate in the movement of the work it is driven by two rollers 210, 211 disposed on opposite sides of an angularly adjustable tongue 209. Lead screws for traversing the mechanism 241, the carriage 117, and the carriage 33 are driven from a motor 268 through a reversing two-speed gear box 269 and suitable transmission mechanism. Specification 606,620, [Group XXIX], also is referred to.