Patent GB-709208-A (GB)
Title: Improvements in or relating to methods of and apparatus for working materials by a shaving or a like operation
Inventor: SMEDLEY JOHN
IPC: B23D79/02
Filed: 1951-02-20
Abstract: 709,208. Planing. ROLLS-ROYCE, Ltd. Feb. 18, 1952 [Feb. 20, 1951], No. 4162/51. Class 83 (3). [Also in Group XXIII] A planing machine, particularly for removing the flash on the leading or trailing edges of forged turbine or compressor blades, comprises a tool 23 having a cutting profile 23a conforming at least partly to the leading or trailing edge section of the blade at its root and rocking means arranged to effect, simultaneously with the cutting stroke, a relative rocking movement of the blade and tool about an axis parallel to the direction of the cutting stroke. The tool 23 is clamped to a holder 24 rotatable in part-cylindrical guides in a saddle 36 and the saddle is reciprocated along a guide 37 by a slotted link mechanism 44, 45 driven by a crank wheel 41 and arranged so that the rate of travel of the saddle is greatest during the return stroke. To relieve the tool during the return stroke, the guide member 37 is pivoted at 47 and is raised by springs 49 upon the withdrawal of cam plates 50 operated by linkage from a cam 55 on the same shaft as the crank wheel 41. A wedge 58 limits the extent to which the guide member is depressed and, to provide feed of the tool towards the blade is withdrawn step-by-step after each reciprocation of the tool saddle by a ratchet mechanism 65 operated by a pin 63 on the saddle ; when the wedge 58 is fully withdrawn, the pin 65a on the ratchet wheel has moved to a position in which it slides freely in the slot 64a in the connecting rod 64 and the wedge thus remains stationary until it is reset. Rotation of the tool holder 24 in its guides is effected by a radius arm 70 which is slotted to engage a lever 72, the angle of inclination of which is varied by an adjustable link 74 connected to a crank 76. A ratchet 78 on the crank 76 is operated by a pin 77 on the saddle so that, if required, the inclination of the lever 72 may be adjusted step-by-step after each reciprocation of the saddle. For stopping the machine at the end of a working operation, a switch 84 is operated by a projection 73 on the crank 76. The blade is held by a vice having a pair of shaped jaws 27 urged apart by a spring and closed by oppositelytapered wedges moved in opposite directions by a hand lever. Locating pins 33, 34 engaging the root and tip of the blade are provided on the vice. When cutting a blade which is of uniform non-tapered section but has a twist of α degrees along its length, the ratchet mechanism 78 for the lever 72 is disconnected and the lever is adjusted by the link 74 to the angle required to give during each stroke, as the tool is fed downwards step-by-step, the same rotation of α degree. If the blade has no twist but tapers from the root 92, Fig. 12B, to the tip 93, the crank 76 and link 74 are set so that, during the first cutting stroke, the tool holder is rotated through an angle #, and only one half of the cutting profile 23a of the tool acts on the blade and this angle is gradually changed by the ratchet 78 indexing the crank 76 after each stroke until the angle is -# and the other half of the tool acts on the blade. If the blade is both twisted and tapered, the tool rotation during each cutting stroke is α but the initial angular position at the beginning of each stroke varies by increments applied by the ratchet 78 from a position represented by α+# to a position represented by α-#. Usually, and particularly when removing flash, the crank 76 will rotate through 360 degrees so that the angular adjustment will be from the initial angular position by increments to the other angular position and then back to the initial position, the feed given by withdrawal of the wedge 58 being applied and completed during the angular adjustment in the first sense. A rocking movement alternative or additional to the movement given to the tool by the lever 72 may be given to the work table by a crank mechanism operating either a wedge engaging a spring-loaded plunger bearing on one side of the pivoted work-table or a sliding member having a pin engaged in a helically-grooved member attached to the work-table. For machining blades in which the axes of symmetry of the root and tip leading-edge sections intersect outside the leading-edge, an additional movement, transverse to the direction of the cutting stroke, may be given to the work table.