GB602788A - Machine for production of screw threads on or in wooden bodies - Google Patents

Abstract

602,788. Lathes. NIELSEN, L. H. Dec. 15, 1945, No. 34002. Convention date, March 15, 1943. [Class 83 (iii)] In a lathe for cutting either tapered or straight screw-threads in wood, either internally as in broom stocks, or externally as on broom handles, the work is secured to a clamp attached to a hollow rotatable cylinder fed towards a rotating cutter by a screw and nut and capable of being displaced to one side by means of an inclined plane. A work head 4, Fig. 1, is mounted on pivots 2 on the machine frame 1 and carries a hollow cylinder 6 on which is cut a lead screw 7. The cylinder may be rotated by a handle 20 and bevel gears 21 or 22 or any other suitable drive and is fed forward when a spring-loaded half-nut 8 is engaged with the lead screw by depressing a pedal 9. When the half-nut is disengaged, the cylinder may be shifted by means of a handle 14 on a ring 16 loosely fitted between collars 15. A socket 30 on the cylinder carries either a pivoted holder 29 with an angular scale and a clamp screw 33 for holding broom stocks, or clamps 37, Fig. 5, for broom handles inserted through the cylinder. The holder 29 has a hole 34 so that the broom stock can be centred by a rod passed through it into the hole already formed in the stock. For cutting taper threads, the work head is moved sideways against the action of a spring 50, Fig. 2, as the cylinder is moved forward by a roller 18 on the ring 16 engaging an inclined guide 19, the roller arm being fitted between guide rails 27. An arm 25 mounted on pivots 26 carries the cutter spindle which is driven by a pulley 46. The arm 25 is moved up into working position against the action of a spring 45 by the pedal 9 which is connected to a rod 44 abutting on the arm by means of a shaft 10 and rods and levers. The movement of the arm is limited by fixed stops or by screws 38, 39. The cutter 47, Fig. 6, for external screw cutting has auxiliary blades 48 fitted in front of it for removing surplus material when cutting taper threads. The cutter 23, Fig. 2, for internal threads is four-fifths of the diameter of the hole to be threaded.