Patent GB-399736-A (GB)
Title: Method of and machine for cutting or machining profiled work pieces
IPC: B23D3/04
Filed: 1933-04-12
Abstract: 399,736. Making turbines &c. ALLM€NNA SVENSKA ELEKTRISKA AKTIEBOLAGET, Vasteras, Sweden. April 12, 1933, No. 10980. Convention date, April 12, 1932. [Classes 83 (ii) and 83 (iii).] Shaping curved surfaces; tools.-In a machine for shaping workpieces such as a turbine blade, Fig. 5, a cylindrical surface 51 and a plane surface 50 forming an angle with the cylindrical surface are generated at the same time by a reciprocating cutting tool, the workpiece being rotated about an axis at rightangles to the plane surface, and if required being also moved in a direction perpendicular to the tool movement. A table 2 movable in the direction of the double arrow a carries a pair of spindles 5, 6 carrying discs 3, 4 respectively, and driven by slidable worm gearing 7, 8. The disc 3 carries a profile bar 13 having a lateral edge 14 conforming with the profile of the cylindrical surface to be formed on the workpiece. The inclination of the edge 14 to the horizontal corresponds to the angle between the longitudinal direction of the blade and the inner end surface 50, the blade being mounted on its disc 4 at the same inclination as the profile bar. A shaft 17, rotatable in a bearing 16, is secured to a bracket 18 having guides for a slide 19 carrying the shaping tool 21 whose cutting edge consists of an arcuate portion with its centre located on the axis 17 and bounded by tangential portions which extend in directions determined by the angle between the two surfaces to be generated. The carriage 19 is reciprocated from a motor 22 through a belt 23, crank disc 24, and a connecting-rod 25 having a pivotal connection 26 with the cutter slide. The profile bar coacts with a guide member 39 having a plane surface 39<1> containing the axis of the member which is located in the same horizontal plane as the axis of the shaft 17. In order to enable the profile bar to roll on the guide, the latter is movable longitudinally on rollers 40. The profile bar is maintained in engagement with the guide by a spring 43. At the beginning of the operation, the profile bar has one of its plane surfaces engaging the guide bar and the tool is positioned against the edge 52 of the blank. During the reciprocation of the tool the discs 3, 4 rotate in unison, thus turning the workpiece while the tool planes the inner surface 50 of the blade foot along a horizontal plane. During the rotation of the disc 3 the edge 14 of the profile bar rolls on the plane surface of the guide bar and controls the linear movements of the table 2 and the workpiece so that the tool reproduces the profile of the bar on the cylindrical part of the workpiece adjacent the surface 50. During rotation of the disc 4, if the tool path remains fixed, the angle between the plane described by the side cutting edge of the tool and a generator of the cylindrical part of the work at the point of operation varies and in order to compensate for this the tool is progressively rotated about the axis of the shaft 17. This is effected by means of a disc 36 mounted on the shaft 17 and carrying a weighted cable secured to a sliding member 34. The upper horizontal surface of this member is engaged by a roller 32 on a crank disc 30 driven from the shaft 11, the roller imparting movement to the member 34 to maintain the correct angular relation between tool and work.