Patent GB-714543-A (GB)
Title: Improvements in and relating to apparatus for making mounts for tubular electric lamps
IPC: H01K3/10
Filed: 1952-06-26
Abstract: 714,543. Making filament-supports for tubular electric lamps. BRITISH THOMSONHOUSTON CO., Ltd. June 26, 1952 [June 30, 1951], No. 16112/52. Class 39 (2) In making mounts or filament supporting structures for electric lamps, discharge tubes and, more particularly, long tubular incandescent lamps, a lamp stem 2 of the form shown in Fig. 2 has a wire stay 7, Fig. 3, welded to it in a machine comprising means for supporting and holding a stem at a work station, and a transfer device provided with jaws for gripping a portion of the wire stay and also provided with a welding electrode which co-operates with a second welding electrode mounted for movement towards it. Preferably the stems are supported in a stem-making apparatus of the form described in Specification 390,807, with holding-jaws 5<SP>1</SP> which hold the stem 2 with a leading-in wire 1 located at a definite position to one side of it. The mount assemblies 3, each comprising a wire stay 7 formed with an angular end portion 8 and having lateral alament supporting wires 9, 10 attached to it by insulating beads 11, are fed intermittently towards the transfer position by supporting them on a table 12 and within V-notches between the teeth of a pair of parallel rack bars 22, 23, Fig. 5, located within the table top and carried by a parallel link oscillatory system arranged beneath them. The link system is controlled by cam-operated rocking arms in such manner that the rack bars 22, 23 are elevated parallel with themselves to lift the mount assemblies from the table, oscillated to carry them forward a step, and then lowered to deposit them within the rack teeth and on the table. Mount assemblies 3 are thus fed forward successively on to a recessed ledge 42 at the front end of the table 12 where they are also located between the open jaws 43, 44 of a transfer arm 45, a slot 47, Fig. 8 (not shown) being formed upon the jaw 43 to receive the mid-portion of the stay wire 7, whilst the end of the latter opposite the bent end 8 rests upon a welding electrode 48 on the end part of the arm 45. The arm 45, which is of substantial length, is pivoted at 46 and shaped near its outer end to form the integral jaw portion 43 which co-operates with the jaw 44 mounted on a pivot 51, Fig. 8 (not shown), and adapted to be opened against the pressure of a spring by a stud 49 on part of a pivoted arm 53 bearing upon a roller mounted on the jaw 44. The stay wire 7 gripped between the jaws 43, 44, is then swung upwardly through 90 degrees into the position indicated by broken lines in Fig. 9, this operation being effected through a rocking-collar 60 pivotally mounted adjacent to the arm 45 and on the same shaft 46 and actuated by a vertical link 70 and cam rod 69, the connection between the rocking collar 60 and arm 45 being effected by an arm 63 extending obliquely from the collar and connected by a spring 61 to a point on the arm 45 ; an adjustment screw 62 is provided. Upon the completion of the transferring movement the upper end of the stay wire 7 is lying across the lower end of the leading-in wire 1 of a stem 2 supported at that position of the stem-making machine, the crossing-point of the wires being also adjacent to the second welding electrode 73 located on the opposite side of the stem from the transferring means. The electrode 73 is reciprocable horizontally within guides carried by a fixed bracket, and is advanced by longitudinal movement of a plunger 74 operated by compressed air admitted to a cylinder 76. The leading-in wire 1 and stay wire 7 are thus squeezed between the movable second electrode 73 and the first electrode 48 carried by the transferring means. Excessive flattening of the wires is prevented by an adjustable stop formed by nuts 78 on a stud 79 carried by a fixed bearing block 75. Welding current is supplied to the fixed electrode 48 through a flexible strap 86 and to electrode 73 through a flexible cable 87. The weld having been made, the movable jaw 44 is opened to release the stay-wire, the transferring means 13 swings outward, and the electrode 73 retracts to allow the partially assembled mount, held within jaws of the stem making machine, to move to the next station B preparatory to the attachment of a brace wire 4 for holding the mount assembly 3 in position in a lamp bulb. The brace wire is formed from part of a wire 92 drawn from a spool 101, Fig. 1, to a position across the angular lower end 8 of the stay wire and welded thereto, after which the said part is severed from the main length of the wire and reshaped to form the braþe. The wire-withdrawing and feeding means may be of known type, and operated to bring the end of the wire 92 transversely across the vertically held stay wire 7 which, during an indexing movement, is brought between the outwardly flared ends of guides 93, 94, Fig. 11, arranged to align it correctly relative to the stem 2. At the end of the movement the free end of the wire 92 is located within a horizontal V-sectioned guide 106, and the adjacent inner portion of the wire and part of the bent end of the stay wire 7 are disposed between a pair of electrodes 107, 108, both of which are movable to clamp the crossed-over portions of the two wires. As shown, the electrode 107 is advanced from below the path of the stem by the admission of compressed air to a cylinder 109, these means being similar to those used for operation of the welding electrode 73. The upper electrode 108 is mounted on an arm 116 carried by a shaft 117 which is movable longitudinally from a position to one side of the path of the stem and is then swung angularly about its axis to bring the electrode 108 into operative position with electrode 107. These movements of the electrode 108 are effected in succession by cam-controlled links and rods. Subsequent to the welding operation the requisite portion of the welded brace wire is severed from the main length of wire 92 by a circular shearing knife 129 which is mounted on an arm 130 carried by a cam-controlled shaft 131 which swings the knife across the end face of a die 99, Fig. 1. In the next indexing movement to station C the lower portion of the stay wire 7 passes into the opening between the flared ends of guides 137, 138, Fig. 1, and then into the restricted space between them. Upon the mount being halted the wire 4 is acted upon by co-operating dies 140, 142, Fig. 12 (not shown) on opposite sides of the offset end 8 of the stay wire 7, the die 140 being carried by a jaw 139 that is rocked forwardly and rearwardly by mounting it on a shaft secured to a cam operated rod 158, while the die 142 is carried by a slide that is reciprocated within guideways by a rod connected to means within a compressed air cylinder. The dies are so shaped that the brace 4 is bent to the form shown in Fig. 4.