GB536931A - Improvements relating to bases for electric lamps and similar articles - Google Patents

Abstract

536,931. Electric lamp caps. BRITISH THOMSON-HOUSTON CO., Ltd. March 21, 1940, No. 5261. Convention date, March 25, 1939. [Class 39 (ii)] [Also in Group XXII] The metallic base shell of an electric lamp or the like is made from a strip of metal 30, Fig. 3, having a number of integral projections 29 by forming into a cylinder and securing its abutting ends by an internal seam 31, Fig. 8. The blank 30 is stamped with projections 29 to serve as bayonet pins or, as shown, as an intermittent screw thread and with notches 34, Fig. 3, sc that the seam 31 does not extend tc the edge 33 which, when the base is fitted, engages the glass bulb 10, Fig. 1. The lead 14 is passed between bulb and base through an opening left by the notches 31 and down the outside of the joint where it is soldered at 28. The rolling of the blank 30 into a cylinder and the formation and pressing inwards of the seam 31, to leave the outer surface smooth except for the projections 29, may be carried out by a known machine used for making short lengths of seamed tubing. After seaming, the edge 37 is rolled or bent inwards to form a flange 23, Fig. 1. One or more of the projections 29 adjacent the edge 33 may be displaced from a true spiral to lock the lamp when screwed into its socket.