GB1438456A - Thread milling machine - Google Patents

Abstract

1438456 Thread milling; gauging BURWELL REED & KINGHORN Ltd 24 March 1975 [5 Feb 1974] 05238/74 Headings B3K and B3B A thread milling machine comprises a cutter head 15 to which a rotary cutter is attached to be driven by a motor 19, the cutter head being mounted for vertical movement on a column 3 extending from a base 1; a rotary work table assembly 5 is mounted on the lower part of the column 3 vertically below the cutter head for rotation about a vertical axis by way of a belt drive 22 by a handle and spindle 20, 23. The cutter head 15 may be adjusted vertically relative to the work table 7 by a screw and wheel 25 and is also provided with a graduated dial 27 for setting the helix angle of the cutter by inclination of the cutter head. The work table assembly is tranversely displaceable on a slideway 35 by a hand wheel 49. In operation a workpiece is secured in an adaptor 11 of the table 7 and an appropriate cutter secured in a collet attachment 17 of the head 15, the angle of the cutter is adjusted by the dial 27 and the head lowered by the wheel 25 to the starting position for forming a thread on the workpiece. The desired depth of thread is obtained by adjusting the work-table along the slide 35 by wheel 49, the table then being locked in position horizontally and the thread is formed by driving the cutter and rotating the work table by way of the handle 23 and belt 22 whilst moving the table vertically by a screw and nut assembly located within the table assembly. The screw and nut assembly is selected prior to the thread milling operation so that the workpiece will have the desired thread pitch. When milling a thread of variable depth, the table 7 is not locked in the horizontal direction and the horizontal movement of the table, after the initial setting, is controlled by a cam 55 attached to the table 7 which co-operates a roller arm 41 to displace the table along the slide 37 and hence the workpiece to vary the depth of thread, the table being returned to its initial position, when the roller leaves the cam, by way of springs 57, 59. An indexing disc may be located on the work-table 7 and is marked with indicia representing stop and start positions for various thread configurations.