JPH05314894A - X-ray tube cathode structure and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce processes for assembling the cathode of an X-ray tube and simplify the work of assembling the same. CONSTITUTION:In a cathode of an X-ray tube which includes a filament 1, a support lead 2, a focusing electrode 3 and an insulator 4, the filament 1 and the support lead 2 are first installed and then the filament 1 and the focusing electrode 3 are positioned relative to each other and the support lead 2, the focusing electrode 3 and the insulator 4 are simultaneously assembled by brazing in a vacuum. An adjusting gap required for positioning the filament 1 and the focusing electrode 3 is provided in the portion where the focusing electrode 3 and the insulator 4 are installed. Therefore assembling work is simplified and the cost of assembling and machining is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray tube cathode structure and a method for manufacturing the cathode.

[0002]

2. Description of the Related Art An example of a conventional cathode structure for an X-ray tube and a method of manufacturing the same is disclosed in JP-A-62-295327.
As for the cathode structure, when assembling the focusing electrode and the filament, the relative position of the filament and the focusing electrode can be accurately measured with respect to a predetermined dimension by attaching the support lead to which the filament is attached to the focusing electrode through the support sleeve and the insulator. It was supposed to be installed at. As the assembly work method, partial attachment such as attachment of the filament and the support lead, attachment of the support sleeve and the insulator, attachment of the support lead and the support sleeve, and attachment of the insulator and the focusing electrode are performed. Then, the assembly of the filament and the focusing electrode was completed by successively performing the above-mentioned steps.

[0003]

The above-mentioned prior art is not considered in terms of simplification of the assembly work, and a multi-step process must be performed from the start to the completion of the cathode assembly, so that the working time is long. However, there is a problem in that it takes a lot of time and takes a long working period. An object of the present invention is to simplify the cathode assembling work of an X-ray tube, and to provide a cathode assembly suitable for that purpose.

[0004]

In order to achieve the above object, according to the present invention, the structure of the X-ray tube cathode assembly is assembled into a filament and a support lead according to the heat resistance classification required for the constituent members. , The support lead, the insulator, and the focusing electrode are simultaneously assembled, and the X-ray tube cathode assembly is formed so as to be assembled in two steps. Further, in order to perform the assembly in two steps, a brazing technique is adopted for attaching the support lead, the insulator and the focusing electrode.

[0005]

According to the operating temperature of each part of the cathode assembly when the X-ray tube is used, the high temperature part and the low temperature part are divided into the minimum temperature range, the material suitable for each temperature range is selected, and the member By taking the joining means, the work process of the assembling work is simplified. Further, since the joining method of members by brazing is suitable for assembling a large number of members at the same time, the assembling work can be simplified by adopting a structure suitable for the operation of the cathode assembly of the X-ray tube.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a filament, 2 and 2a are support leads, 3 is a focusing electrode, 4 is an insulator, and 5 and 5a and 6 are brazing materials. When the X-ray tube is used, the coil portion that emits thermoelectrons of the filament 1 operates at a high temperature of 2,000 ° C. or higher, so the filament 1, the support leads 2 and 2a, and their attachment should endure the operating conditions. There must be. Usually, the filament 1 is made of a tungsten wire, the supporting leads 2 and 2a are made of a heat resistant metal such as molybdenum, and the filament 1 is assembled by welding to one end of the supporting leads 2 and 2a. The other ends of the support leads 2 and 2a are connected to terminals from a filament heating electrode (not shown). Most of the heat generated in the filament 1 is radiated by heat radiation, but is partially radiated by heat conduction through the support leads 2 and 2a. At this time, at the other ends of the support leads 2 and 2a (on the side for connecting the filament heating power source), the temperature has dropped to about 500 ° C., so that the other cathode assembly portions should be able to withstand at least that temperature. The support lead 2 is attached to the focusing electrode 3 arranged around the filament 1 via an insulator 4, and the support lead 2 a is directly attached to the focusing electrode 3.

When assembling the support leads 2, 2a, the focusing electrode 3, and the insulator 4, the linear brazing material 5, 5 is attached to the connecting portion of each member.
5a or a plate-shaped brazing material 6 is placed, and the brazing material is heated and melted in a vacuum. In this case, since the relative position between the filament 1 and the focusing electrode 3 is related to the dimensional accuracy of the X-ray tube focus, an auxiliary tool (not shown) such as a brazing jig is used to accurately determine this relative position. Hold. Since each brazing material should have a heat resistance of 500 ° C. or more in use, an ordinary brazing material such as copper, silver, gold or an alloy of those metals can be used, but the brazing of the insulator 4 For this reason, when the brazing part of the insulator 4 is not subjected to the metallizing treatment, each metal containing a reducing metal such as titanium (Ti) or nickel-titanium (Ni-Ti) alloy is used.

Further, the insulator 4 has a problem that it is difficult to obtain high dimensional accuracy due to its manufacturing convenience.
A mounting seat 9 is provided on the focusing electrode 3 and an adjustment gap 7 is provided between the focusing electrode 3 and the insulator 4 so that the dimensional accuracy difference can be corrected. The insulator 4 has an inner diameter of the insulator 4 and the support lead 2 in order to maintain electrical insulation between the focusing electrode 3 and the support lead 2.
It is preferable that a recess 8 for preventing the adhesion of the brazing material is provided between and to prevent the insulation from being deteriorated by the brazing material.

FIG. 2 shows another embodiment of the present invention. A protrusion 10 is provided on the insulator 4a, and the protrusion 10 is inserted into the hole of the focusing electrode 3 and an adjustment gap 11 is provided between the protrusion 10 and the focusing electrode 3 to adjust the position. Support lead 2 and focusing electrode 3
Maintain electrical insulation between.

According to the above embodiment, the cathode of the X-ray tube is a two-step process of assembling the filament 1 and the supporting leads 2 and 2a and assembling the supporting leads 2 and 2a and the focusing electrode 3. It becomes possible to assemble with, and the work is simplified. In addition, since the brazing work is performed in a vacuum, the gas components remaining in the cathode assembly are also exhausted and reduced, and the degassing after being incorporated in the X-ray tube becomes easy.
It is possible to obtain a high-quality cathode assembly that is free from the possibility of a decrease in the degree of vacuum caused by the release of gas when using a wire tube.

[0011]

According to the present invention, since the assembly of the cathode is simplified, the working time is shortened and the processing cost is reduced. In addition, since the cathode constituent member can be made to have a minimum required for its function and the cathode assembly has a small residual gas, it is highly economical in manufacturing an X-ray tube.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a cathode assembly according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a cathode assembly according to another embodiment of the present invention.

[Explanation of symbols]

 1 Filament 2 Support lead 2a Support lead 3 Focusing electrode 4 Insulator 4a Insulator 5 Wire brazing material 5a Wire brazing material 6 Plate brazing wire 6a Plate brazing wire 7 Adjusting gap 8 Recess 10 Protrusion 11 Adjusting clearance

Claims (5)

[Claims] 1. An X-ray tube cathode assembly comprising a filament, a filament supporting lead, a focusing electrode, and an insulator, wherein after the filament and the filament supporting lead are assembled, the relative positions of the filament and the focusing electrode are determined. A method for manufacturing an X-ray tube cathode assembly, characterized in that a filament supporting lead, a focusing electrode and an insulator are simultaneously assembled by brazing in a vacuum. 2. An X-ray tube cathode assembly comprising a filament, a filament supporting lead, a focusing electrode and an insulator, wherein the filament supporting lead, the focusing electrode and the insulator are simultaneously assembled by brazing. Characteristic X-ray tube cathode assembly. 3. An adjusting clearance for adjusting a dimension at the time of relative positioning of the filament and the focusing electrode is provided on the mounting seat of the insulator with respect to the focusing electrode.
The described X-ray tube cathode assembly. 4. A focusing electrode of an insulator and a surface to be brazed,
4. The X-ray tube cathode assembly according to claim 3, further comprising a recess for maintaining electrical insulation between the filament supporting lead and the focusing electrode. 5. A protrusion is provided on the side of the insulator that is attached to the focusing electrode, the protrusion is inserted into the focusing electrode, and an adjusting gap is provided between the outer diameter of the protrusion and the focusing electrode. The X-ray tube cathode assembly according to claim 2.