| 摘要 |
1,034,990. Making heaters for electron tubes; coiling. RADIO CORPORATION OF AMERICA. Nov. 23, 1964 [Dec. 30, 1963], No. 47537/64. Headings B3A and B3E. A method of making heaters for electron tubes comprises winding a wire on a mandrel, winding the wire wound into a helix and separating the turns of the helix from one another to form a plurality of shaped heater workpieces. As described, tungsten wire is wound on to a molybdenum mandrel and the wire wound mandrel is wound helically on to two spaced parallel support rods, one having a larger diameter than the other to produce a helix having triangular turns. The two support rods are rotated and moved axially and the turns of the helix are secured to the larger rod by notching the rod and closing the notches. The smaller rod is then removed leaving the helix attached to the larger rod which may be annealed by firing at 800‹ C. in a hydrogen atmosphere. The supporting rod may be bowed on leaving the winding apparatus and this bow is removed by stretching the rod and applying a reverse bow. The helix is then coated with insulating material, e.g. aluminium oxide, by dipping the turns of the helix into a bath of insulating material, leaving the region of the helix adjacent the rod uncoated. The individual terms are then cut from the rod and the molybdenum mandrel is dissolved using a mixture of sulphuric and nitric acids to produce a heater consisting of a V-shaped coil which is coated with insulating material except for the end portions. |
