GB836134A - Improvements relating to the jointing of glass parts - Google Patents

Abstract

836,134. Joining cathode-ray tube envelope parts. SIEMENS EDISON SWAN Ltd. Jan. 9, 1958 [Jan. 15, 1957], No. 1550/57. Class 56. A process of joining the screen closure member to the body portion of a cathode ray tube consists in heating the respective rims while they are rotated almost in contract, to a temperature at which the glass becomes electrically conductive and passing an electrical discharge through the heated glass at the joint by means of electrodes located in proximity to the rims and substantially equiangularly spaced around the longitudinal axis, the electrodes directing flames on to the joint and being connected each to a separate phase terminal of a polyphase supply so that the joint is uniformly heated by the current passed through the heated glass between the' phase arcs to the glass and a substantially balanced load is taken from the supply. As shown in Fig. 3 an apparatus for joining the screen closure member to the body portion of a glass envelope for a cathode ray tube comprises chucks 10 for holding and rotating the closure member and body portion in axial alignment, a stationary member 12 supporting co-axial with the chucks equiangularly positioned insulators 16 each carrying a hollow electrode 2 directed towards the location of the joint between the screen closure member and a body portion when supported within the chuck, pipes 14 for supplying burner gas to the electrodes whereby to produce flames for heating the joint, and also a battery of heating flames 13 preferably uniformly spaced around the longitudinal axis of the chuck, and a polyphase supply having phase terminals respectively connected to the electrodes whereby, when the glass at the joint has been heated to cause the glass to become electrically conductive, polyphase arcs can be produced between the electrodes and the glass by the flames to complete the welding of the joint between the closure member and body portion of the envelope. For sealing a closure member of non-circular configuration to a correspondingly shaped body portion of a cathode ray tube envelope, the insulators are each mounted on a link pivotally connected with the stationary member, the links being engaged by a cam rotatable with one of the chucks and shaped to the configuration of the closure member so that the electrodes are, by radial displacement, caused to follow the configuration of the joint. Specification 751,196 is referred to.