Patent GB-763802-A (GB)
Title: Machine for assembling spark plug electrodes
Inventor: CHRISTIE ROBERT KELVIN
IPC: H01T21/02
Filed: 1955-01-25
Abstract: 763,802. Making sparking plugs. CHAMPION SPARK PLUG CO. Jan. 25, 1955, No. 2176/55. Class 7 (4). DESCRIPTION (a) General The invention relates to automatic and continuous means for introducing sealing material between a sparking plug insulator and electrode and compacting the material. The tubular shaft 19, Fig. 1, which is driven by an electric motor 12 through a chain 13 and worm gearing 15, 17 has a drum 22 connected thereto that supports on its exterior a number of filling and tamping stations 27. (b) Tamping and filling stations Each station comprises an upper and a lower part, the latter consisting of a reciprocating cylinder 28, Fig. 4, in which slides a piston 33 provided with a neck 35 that has a fixture 38 attached thereto for the reception of a sparking plug insulator 40. To the lower end of the cylinder 28 is fixed one end 43 of a bell-crank lever 44, Fig. 1, the other end 46 of which contacts a stationary cam profile 47 bolted to the frame 21 that supports the shaft 19. A conduit 49, Fig. 4, which opens into the lower part of the cylinder 28 is connected to a manifold 50, Fig. 1, that opens through a pipe 51 to a fluid-pressure accumulator chamber 52 into which extends a plunger 54 loaded by weights 57; a constant pressure is thereby exerted on each piston. Each upper station part comprises a bracket 71 supporting a pair of parallel rods 72, 73; Fig. 4, on which reciprocates a slide 76 formed with a block 80 having a lower plate in which is a coned aperture 81 ; a feeder plate oscillates on the rod 72 in the block 80 and is rotated as the slide 76 moves downwards by a cam slot on the rod 72 so as to connect a hole in the feeder plate with a tube 90, Fig. 1, that leads to a receptacle 91 of powdered or fibrous sealing material which may include electrically conducting substances ; the hole bemg aligned with the open electrode bore of the insulator 40, Fig. 4. The brackets 71 are each provided with a tube 93 housing a -hollow removable and adjustable tamping tool 92, the tube also containing a plunger 98 to which is attached a drill 99 for cleaning purposes. In a modification, the lower station parts are fixed and the upper parts arranged to reciprocate ; the insulator may be held in the horizontal position when the material to be inserted in the bore is fibrous. Where the central electrode does not extend into the core of the insulator, the material may be deposited on top of the electrode in which case the tamping tool is solid. As the drum 22, Fig. 1, rotates the ends 46 of the levers 44 ride on the cam 47 and effect reciprocation of the cylinders 28 between the two extreme positions shown. The cam 47 is arranged so that during one operation the cylinders remain in their lowest position for a period to enable the operator to remove a tamped insulator and refill the fixture 38, Fig. 4, with another insulator and centre electrode; during the remaining part of the rotation each cylinder is elevated and lowered four times to receive a corresponding number of powder charges in the insulator bore around the electrode, each charge being separately tamped. The powder is delivered through the feeder plate and tamped by the tool 92; upward movement of the cylinder causes the centre electrode to force the spring-loaded drill 99 out of the bore of the tool 92 whilst subsequent downward movement of the cylinder allows the drill to be urged by its spring through the tool to clean it. The drill may also be rotated during the cleaning operation by a friction surface 105, Fig. 1, on a bracket 104 engaging a knurled knob 103, Fig. 4, on the top of each drill. The tamping pressure of each successive powder charge is determined by the pressure in the fluid system which in turn depends upon the number of accumulator weights used. To compensate for the reduced movement of the tool 92 necessary to compact the successive powder charges the piston 33 is moved downwards after each tamping operation thereby expelling fluid from the cylinder 28 and forcing the weights 57, Fig. 1, and plunger 54 upwardly ; excessive or insufficient upward and downward movement of the plunger 54 due to a jammed or broken tool 92 for example may cause operation of limit switches 106 and hence de-energization of the motor 12.