JPH0286026A - Manufacture of electron tube cathode heater - Google Patents

Abstract

PURPOSE:To make a cathode heater small-sized and make the heating power efficient by winding a tungsten wire upward from below along one spiral groove of a mandrel and winding it downward from above along the spiral trough section of its surface. CONSTITUTION:A molybdenum fine wire 12 is wound on the outer periphery of a tungsten wire 11, which is wound upward from below along the spiral groove 21 of a mandrel 2. The winding direction is changed along the groove 22 at the top section, and the tungsten wire 11 is wound downward from above along the spiral trough portion formed between the wire 1 previously wound upward from below on the mandrel 2 on the wire 1. Subsequently stress distortion is removed by heat treatment, then the molybdenum fine wire 12 closely wound on the outer periphery of the tungsten wire 11 is solved and removed. The winding pitch is narrow, a heater is made small-sized, and the efficiency of the heating power can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a helical coil heater for an electron tube cathode.

[Conventional technology]

Helical coil heaters are widely used for cathode heaters in cathode ray tubes, klystrons, traveling wave tubes, and the like.

FIG. 2(,) shows an example of a conventional helical coil cathode heater.

The coil part is made by winding a tungsten wire in a spiral shape from the bottom, folding it back in the opposite direction at the tip, and winding it down in a spiral manner between the wound tungsten wires.

With this structure, the current flowing through the tungsten wire in the coil is in the opposite direction to the current flowing through the adjacent tungsten wire, and the magnetic fields induced by the current cancel each other out, and the electron beam emitted from the cathode is stimulated by the heater current. It has the advantage of not being adversely affected by magnetic fields.

However, if the pitch P of the coil portion is narrowed, short circuits are likely to occur, and the pinch cannot be narrowed beyond a certain limit, which limits the overall length, that is, the dimension in the axial direction, and limits miniaturization.

The fabrication of the cathode heater shown in Fig. 2(,) is as shown in Fig. 2(b).
), a mandrel with two parallel spiral grooves adjacent to each other is used, and a fine molybdenum wire is tightly wound around the outer periphery of a tungsten wire to form one spiral groove on the mandrel. Wind from the bottom to the head along the mandrel, change the winding direction along the groove that crosses approximately the center of the head provided on the head of the mandrel, and then wrap from the head to the bottom along the other spiral groove. This is done by dissolving and removing thin molybdenum wires tightly wound around the outer periphery of the tungsten wire. Therefore, when the pitch is narrowed, winding becomes difficult, and it becomes difficult to groove the mandrel.

[Problem to be solved by the invention]

Conventionally, when trying to narrow the pitch of the coil part in a helical coil cathode heater, as mentioned above, there are limitations such as shorting of the coil part, difficulty in winding, and difficulty in machining grooves on the mandrel. There was a problem.

The present invention was made to solve the above problems.
A method for manufacturing a helical coil cathode heater that does not cause short circuits in the coil portion even if the pitch of the coil portion is narrowed, does not make it difficult to groove the mandrel used, and does not make winding difficult. The purpose is to provide.

[Means to solve the problem]

The method of the present invention involves tightly winding a thin molybdenum wire around the outer periphery of a tungsten wire and winding it around a mandrel from the bottom toward the head along a single spiral groove provided on the mandrel.
The winding direction is changed along a groove provided so as to cross almost the center of the head of the mandrel, and a spiral shape is formed on the part of the mandrel that was previously wound from the bottom toward the head. The tungsten wire is manufactured by winding it from the head of the mandrel downwards along the troughs, heat-treating it to remove stress and strain, and melting and removing the thin molybdenum wire tightly wound around the outer periphery of the tungsten wire.

〔Example〕

An example of the manufacturing method of the present invention will be explained below with reference to FIGS. 1(a), (b), and (c).

In the figure, ■ is a wire in which a thin molybdenum wire 12 is tightly wound around the outer periphery of a tungsten wire 11, and 2 is a spiral groove 21 on the side surface and a groove 22 on the head that is connected to the groove 21 and crosses almost the center of the head. It is a mandrel with a

ri/gustey#i! A thin molybdenum wire 12 is tightly wound around the outer circumference of the mandrel 2 [Fig.
Figure (b)] is wound from the bottom to the head along the spiral groove 21, the winding direction is changed along the groove 22 in the head, and the winding is wrapped around the mandrel 2 from the bottom to the head. From above the wound wire 1, wrap it from the head to the bottom along the spiral valley formed between the wires 1 [Fig. 1 (C)],
The stress strain is removed by heat treatment, and then the thin molybdenum wire 12 tightly wound around the outer periphery of the tungsten wire 11 is dissolved and removed.

According to this method, since the mandrel 2 used has one spiral groove 21, groove processing is easy even when the pitch is narrowed.

In addition, the wire 1 can be wound around the mandrel 2 along the single spiral groove 21 and the trough formed between the previously wound wire 1, so even if the pitch is to be narrowed, winding is difficult. It never becomes.

The tungsten wire 11 in the coil portion is different from the adjacent wire 11 in the first place.
Since the arrangement is shown in figure (c), even if the pitch is narrowed,
It is much less prone to short circuits than conventional ones.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to easily obtain a narrower edge than in the conventional method, which is advantageous for downsizing and increasing the efficiency of heating power.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (e) are cross-sectional views showing an example of the manufacturing method of the present invention, and FIG. 2(,) is a perspective view showing an example of a conventional helical coil-shaped cathode heater. FIG. 2(b) is a perspective view showing an example of a mandrel used for manufacturing the cathode heater of FIG. 2(a). 1...Molybdenum thin wire 1 on the outer periphery of the tungsten wire 11
A wire tightly wound with 2, 2...mandrel, 21.22...groove. In the drawings, the same reference numerals indicate the same parts.

Claims (1)

[Claims] The process of tightly winding a thin molybdenum wire around the outer circumference of a tungsten wire.The tungsten wire tightly wound with the thin molybdenum wire is wound around a mandrel from the bottom toward the head along a single spiral groove provided on the mandrel. , the winding direction is changed along a groove provided to cross almost the center of the head of the mandrel, and a spiral is formed on the part of the mandrel that was previously wrapped from the bottom toward the head. a step of winding the tungsten wire from the head to the bottom of the mandrel along the valley portion of the shape; a step of heat-treating the tungsten wire in which the thin molybdenum wire wound around the mandrel is tightly wound to remove stress strain; A method of manufacturing a heater for an electron tube cathode, which includes a process of dissolving and removing a fine molybdenum wire tightly wound around the wire.