GB1071220A - Machine tool and method of using the same - Google Patents

Abstract

1,071,220. Milling; grinding. CARL HURTH MASCHINEN UND ZAHNRADFABRIK. Oct. 6, 1964 [Oct. 9, 1963], No. 40670/64. Headings B3B, B3D and B3K. A machine tool for cutting or grinding a two-sided groove (such as a key-way) comprises a crank mechanism 19, 22 for feeding the tool along the groove, a steplessly variable drive 32 for modifying the quasi-sinusoidal motion of the crank drive by varying the speed of input to the crank mechanism, and means 74 for enabling the tool to be displaced transversely after making a cut. The work 9 is clamped on a slide 12 mounted on a slide 5 carried on a vertically-movable knee 3. The belt-driven tool 16 is carried in an axially-movable sleeve 17 in a slide 15. The slide 15 is reciprocated by the adjustable crank 19, Fig. 4, rotated by a motor 38 through the steplessly-variable gearing 32, belt or change-speed gearing 48 to 58, and a worm 24, the gearing being continuously adjusted by a cam 36 and a lever 35 to produce a substantially constant speed of the slide. A further crank 67 rotates linkage 69, 71 to oscillate a pawl 73 which rotates a ratchet 74 to feed the work towards the tool. A clutch 82 transmits the rotation of the ratchet 73 or of a worm wheel 85 to a screw 80 which feeds the slide 5. The worm wheel 85 is rotated by an electric motor to enable a rapid return motion or a drilling feed to depth to be effected. The screw may also be rotated manually and the pawl 73 may be lifted clear by power means. Cams 88, 89, 91, 92, 93 operate hydraulic or electrical control means. The work can be fed vertically by rotating a screw 114 by an hydraulic or electric motor. Alternatively, a cam 108 is rotated by a motor 117 to move a lever upon which the end of the screw 114 rests. The fulcrum of the lever 106 may be adjusted manually or automatically by a motor applied to a connection 102a thus - enabling a conical key-way to be cut or wear of a grinding wheel to be compensated. Adjustment of the fulcrum also determines the width of slot to be cut. In operation, the work is fed into the cutter to drill the end of the slot centrally, the cutter is traversed the length of the slot to take a rough cut, the work is then raised or lowered and, on a return tool traverse, one side of the slot is finished. Finally, the work is moved in the opposite direction and the other wall is finished. More than one finishing cut may be made with in-feed between cuts. Since the cutter is moving while the work is raised or lowered, the end of the slot is curved. In a modification, the tool is mounted in a planetary carrier so that it can be moved in a circular path to machine the end of a slot. Further modifications include processes in which the centre of the slot is milled to depth in several passes and the sides are each finished in a single pass, or one side of a slot is first milled and then the other.