Patent GB-633550-A (GB)
Title: Improvements in or relating to profile generating machines
IPC: B23Q35/10
Filed: 1946-06-25
Abstract: 633,550. Profile-generating grinding-machines. FAIREY AVIATION CO., Ltd., and LYON, G. June 25, 1946, No. 18987. [Class 60] [Also in Group XXII] A profile-generating machine for the production of blades for axial flow air compressors, impellers, turbines and the like has a shaping tool arranged to be moved in consonance with a tracer as the latter follows the contour of the surface of a rectilinearly-reciprocated master form, and has the work arranged so that its bodily movement is geometrically on the surface of a cone whereby movements of the tracer according to master form ordinates measured from a flat base will produce finished work having a profile similar to that of the master form but with the ordinates measured from a base of predetermined curvature. The machine may also be used in the manufacture of dies for the production of blades by forging, pressing, coining, moulding or casting. The work may also differ from the master form in taper, breadth and degree of twist, and be cambered lengthwise by the application of a bending load to the master form. In Fig. 1, a indicates the profile of the master form, b its chord or base, and c1-c6, d1-d6 ordinates; e indicates the work with a curved base f, the lengths of the ordinates g1-g6 and h1-h6 being the same as those of the corresponding ordinates in the master form. The tracer k, Fig. 2, and tool j, are carried by a balanced arm m pivoted on a table 48 about an axis nn. The drive for the tool is through a belt q, pulleys r, s, shafts t, w, and a universal joint v. The table 48 is traversed by a lead-screw 50, driven from a gear train actuated by a pawl 54, Fig. 3, and a ratchet-wheel 55, the pawl 54 being carried on a rod 52 reciprocated by a table which supports a second table y and a-block x to mount the master form. A table z is reciprocated parallel to the axis nn by a crankpin 13 engaging a cross-head 14 slidable in a slot 15 in the table. The crank-pin is adjustable to vary the stroke of the table and a shaft 19 is driven by a worm 18 and a worm-wheel 17. The table y can be traversed in a direction perpendicular to the axis nn by a lead screw 21 rotated through a gear train by a ratchet-wheel 26 which is traversed by a table z periodically to strike a pawl 27. For the purpose of oscillating the work, one of its ends is held by a shaft 30, Fig. 5, while the other end is secured to a partly cut-away portion of a shaft 31. The former shaft is carried in a bearing 32 which is adjustable on an arm 33, to one side of the lower end of which a splined lug 34 is secured which engages one end of a splined shaft 35 supported in angularly-adjustable bearings 36, 37, on an adjustable pedestal 38. The mounting and supports for the shaft 31 are similar. A toothed segment 45, secured to the shaft 35, meshes with a rack cut in a rod 61 reciprocated by a rod 63 through a lever 79 provided with a slot 78 to accommodate pins 83, 77 formed on collars 82, 76, adjustably secured to the rods. The lever 79 is pivoted on a block 81, and the rod 63, which is slidably mounted on the table 48, is reciprocated by a cross-head 73 and a crank-pin 70 driven by a worm-wheel 66, a worm 65 and shaft 19. Traverse of the table 48 transversely displaces the rod 63 to cause the amplitude of oscillation of the work to be progressively reduced. The pivot for the lever 79 may be carried on a bracket forming part of the table 48.  To impart a twist or a varying pitch angle to the work, the reciprocations of the master form are accompanied by angular displacements of the work about its longitudinal axis. The shaft 30 is turned by a worm-wheel 84 driven through a worm 85, Fig. 3, shaft 86, universal joints 88, 90, an intermediate shaft 89 and shaft 91 slidably splined to a gear-wheel 92 meshing with a pinion 93. A ratchet-wheel 94, Fig. 2, and-pawl 95 carried by a rod 96 reciprocated by the table z rotate the pinion 93. Correct meshing between the toothed segment 45 and the rack may be secured for all adjusted positions of the work by one or more of the following methods: (1) The segment 45 is fixed at different axial positions on its shaft 35 or is replaced by another of different pitch circle radius. (2) The guides 62, 62 are vertically adjusted,' the height of the associated parts also being adjusted. (3) The collar 82 is angularly adjustable on the rod 61 to maintain the pin 83 vertical when the rod is turned in its mountings. The concave surface of the work is machined by inverting the work-supporting arrangement. In this case, the shaft 35 is mounted in the manner previously described but with the pedestals 38 and 44 adjustably bolted to a cantilever 121. The universal joint 88 is disconnected and the other end of the shaft 86 is connected with the shaft 89. The pawl is moved along the rod 52 and bearings for the ratchet-wheel 94 and the gear-wheel 92 are fixed in positions corresponding with the new position of the splined shaft 91. To produce longitudinally cambered work, the master form is bowed by the application of a bending load as shown in Fig. 17. The table y has a bracket 123 supporting a rotatable spindle 124 having a tapped diametrical hole to receive one end of a differentially-threaded screw 125, the other end of which is received in a similar hole in a spindle 126 carried by an arm 127 fast with a spindle 128. Two extensions, one at each end of the master form, are secured one in the spindle 128 and one in a spindle 132 supported in a member 133 which is threaded into a sleeve 135 in turn threaded into the table y, the interior and exterior of the sleeve having threads of opposite hand. When the tool and tracer are of large diameter in relation to the work, the distortion due to the point of contact of the tool with the work departing from the vertical plane through the axis of the tool and the axis of oscillation of the work when the latter is inclined, is overcome by the mechanism shown in Fig. 20. The arm m is formed with two arcuate, undercut, guideways 136, 137 having centres of curvature coincident with the operative points of the tracer and the tool. Blocks 140, 141, slidably mounted in the guideways, carry the tracer and the tool, the two blocks being connected by a link 144 pivotally connected at 148 to a second link 147 pivoted to the arm m at 149. The link 144 is operated by means of an electricallycontrolled hydraulic jack, the cylinder 150 of which is pivotally anchored at 151 to the arm m, while the plunger 153 is connected to the link 144. Control of the jack is effected by means of a feeler lever 156, Fig. 21, pivoted at 157 to a plate 158 fast with the shaft carrying the tracer. The lower end of the feeler lever is provided with a flat edge in contact with the master form close to the operative point of the tracer, while the upper end supports an electric contact to co-operate with two contacts supported on the plate 158. When the flat edge of the feeler lever is parallel with the tangent to the operative point of the tracer the upper end of the feeler lever is midway between the fixed contacts which are connected to an electric device controlling the flow of fluid to the jack. Movement of the master form tilts the feeler lever to establish a circuit with the device thus causing the jack to operate and displace the blocks 140, 141 until the tangent to the operative point of the tracer is parallel with the flat edge of the feeler lever. A gravity-operated device keeps the tool driving belt taut during these movements. The hydraulic jack may be replaced by an electric actuator and the contacts may be replaced by micro switches. When the curvature of the work is to be other than circular, a modified machine shown in plan in Fig. 23 is used. The tool and tracer are supported by an arm m pivoted on an axis nn, the tracer being adjustable along the arm. Two shafts 30, 31 support the work and the shaft 30 is carried in a bearing secured to a cheekplate 177 through an intermediate block having a curved upper face. The shaft 31 is similarly arranged with a cheekplate 179. Both cheekplates are provided with slots of shape corresponding to the required path of the work to accommodate pegs 185, 186 projecting from the vertical faces of two supports 187, 188. Flexible metal strips 191, 192 attached to opposite edges of the intermediate blocks lie in opposite directions over the upper surfaces thereof and are attached to beams 194 and 195, reciprocated by crank-pins 200 driven from the shaft 19 to cause the work-piece to alternate over the pre-determined path.