Patent GB-721525-A (GB)
Title: Improvements in and relating to lamp stem making machines
IPC: H01J9/42
Filed: 1952-12-23
Abstract: 721,525. Making electric lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 23, 1952 [Dec. 26, 1951]. No. 32623/52. Class 39 (2). A device for detecting the presence, absence or faulty formation or location of a wire or similar structure forming part of the mount structure of an electric lamp or the like, comprises a sensing or detecting finger or feeler mounted upon a lever that is made at least in part of magnetic material and pivoted upon a movable support upon which a control magnet is mounted, means being provided for moving the support towards the mount structure so that the presence and correct location of a wire causes the sensing- lever to be displaced away from the magnet whereas the absence or displaced location of a wire produces no displacement of the sensing- lever and results in the operation of an indicator. In the example the detecting device is mounted below and outward from the circular path 10 of movement of work-carrying heads 2 mounted around the periphery of a machine corresponding to the stem-making portion of the automatic mount-making machine described in Specification 390,807, and is preferably located at the station following that at which leading-in wires, e.g. four wires 3 ... 6 are fed into the head. The leading- in wires are located within a stem-tube 30 that is held between a pair of jaws 31, 32 above a leading-in wire holder consisting of a fixed centre jaw 27 and a pair of separable outer jaws 28, 29 which have recesses or pockets for the retention of the lower ends of the leading-in wires, thereby maintaining them in position during the operation of the sensing or detecting device. This device comprises four feeler levers 8-11, Fig. 2 (not shown) of magnetic material. such as steel, all similar to lever 8 and carried on a common pivot 12 intermediate their ends and each provided with an upper sensing-end 7, the pivot 12 being mounted on a supporting lever 13 which is pivoted at 14 to a bracket 15 secured at the upper end of a' fixed column 16. An operating arm 18 pivoted to the lever 13 at 19 is actuated by the upward movement of a rod 17, and a tensioned helical spring 20 is connected between the arm 18 and a pin at the lower end of the lever 3, the normal inoperative position being such that the arm 18 bears upon a stop-screw 21 mounted on the side of the lever 13. A relatively strong magnet 22 is adjustably mounted on the lever 13 and normally holds the lower portions 23 of the feeler levers 8 and 9-11 (not shown) against a lateral post 24 on the lever 13. The operating rod 17 is moved upwardly when a work-holding head is indexed into position opposite the detector, whereupon the lever 13 is swung inwardly and the sensing ends 7 of the feeler levers either pass through the position that should be occupied by a corresponding leading-in wire that is either displaced or missing, or butt against the wires 3 ... 6 so that the feeler levers are pushed back and swung clockwise about the pin 12, against the resistance furnished by the attraction of the magnet 22. When a leading-in wire is missing or is not located correctly the lower end of the relevant feeler remains in abutment with the post 24, and the upward movement of rod 17 and the consequent swing of arm 18 cause the outer end of a resilient arm 35 to be pressed upon a toe at the lower end of the said feeler lever, the other end of the arm 35 being secured upon the cover of a switch 36 provided with a push button 35' which is depressed by deflection of the intermediate part of the arm 35. The circuit of a signal lamp 37 is thus closed and the defect indicated. Means are also provided for rendering the detecting device inoperative in the event of a stem tube 30 being missing from the head 2, and comprise an upright lever 70 pivoted to the supporting lever 13 at 71 and provided with a transverse rod or finger 72 arranged to bear upon a stem tube 30 held between the jaws 31, 32. The lever 70 is thereby swung clockwise when the rod 17 lifts the arm 18, so that a lateral post 73 on the lower end of the lever 70 is moved away from the feeler levers. If the finger 72 does not contact a stem tube 30 the post 73 will block movement of the feeler levers. Specifications 446,382 and 484,430 also are referred to.