JP2001135252A - Manufacturing method for vacuum envelope of traveling-wave tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of axial deviation between pole-piece and spacer in manufacture of vacuum envelopes, eliminating need of jig for central collimation and problem of joint to the jig. SOLUTION: For the structure of assembling pole-pieces 1 and spacers 2, centering of the vacuum envelope is made simple, when the both are assembled alternately, by using the pole-piece 1 and spacer 2 which has a concave on one side while a convex at the other side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a vacuum envelope of a traveling wave tube.

[0002]

2. Description of the Related Art FIG. 9 is a schematic sectional view of a conventional vacuum envelope 3 disclosed in, for example, JP-A-6-20615. FIG. 9 shows the upper half of a cross-sectional view along the central axis of the hollow vacuum envelope. There is also a lower half symmetrical to the axis, but this is omitted. FIG. 10 is a schematic sectional view of a slow wave circuit using a general spiral transmission line 4. The spiral transmission line 4 is supported by the support 5 so that the vacuum envelope 3
It is arranged concentrically inside. The metal loading element 6 is arranged in a space formed by the transmission line 4, the support 5, and the vacuum envelope 3.

Usually, a vacuum envelope 3 of a slow wave circuit of a traveling wave tube is used.
Has a structure in which ring-shaped pole pieces 1 made of a ferromagnetic material and ring-shaped spacers 2 made of a non-magnetic material are alternately joined. The method of manufacturing the vacuum envelope 3 is such that the pole pieces 1 and the spacers 2 are alternately mounted on a centering jig of the vacuum envelope 3 and hermetically joined by brazing or the like. After the hermetic joining, the microwave transmission line 4 is placed at the center of the vacuum envelope 3,
A hole for inserting and supporting the support 5 and the metal loading element 6 is cut.

[0004]

In the conventional method of manufacturing the vacuum envelope 3, when the pole piece 1 and the spacer 2 are mounted, an uneven clearance is generated between the center axis setting jig and the vacuum envelope. Axis alignment is difficult and axis deviation occurs.
In addition, there has been a problem that the pole piece 1 and the spacer 2 are joined to the centering jig during the hermetic joining process due to misalignment.

[0005] The vacuum envelope of the TWT includes a single part (pole piece, spacer) of about 2 mm coaxially with a total length of about 10 mm.
Combined up to about 0mm, the axis deviation is less than 100μm. Therefore, if the shaft misalignment is 100μ or more, there will be a problem that assembly cannot be performed. Also, regarding the joining of jigs and pole pieces, etc., if this phenomenon occurs during manufacturing, products cannot be secured (it becomes impossible to remove them from jigs), so they are treated as a major problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In the manufacture of a vacuum envelope 3, the jig and the pole piece are prevented by suppressing the occurrence of an axial misalignment between the pole piece 1 and the spacer 2. And the like are prevented from being joined in a brazing process. Further, it is another object of the present invention to eliminate the need for a centering jig when the cutting hole 9 is misaligned at the time of cutting and airtight joining.

[0007]

According to the method for manufacturing a vacuum envelope of a traveling wave tube according to the present invention, in a combined structure of a pole piece and a spacer, one of the joints is concave and the other is a joint. A pole piece 1 having a convex shape and a spacer 2 having one joint having a convex shape and the other having a concave shape are used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 One embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the combination of a pole piece 1 made of a ferromagnetic ring and a spacer 2 made of a non-magnetic ring has one convex shape and the other concave shape. Looking at the pole piece 1, there are two joints with the spacer 2 on the left and right in the figure, the right joint has a convex shape, and the left joint has a concave shape. As for the spacer 2, there are two joints with the pole piece 1 on the left and right sides of the figure, the right joint has a convex shape, and the left joint has a concave shape. At the center of the pole piece 1 and the spacer 2, a hole (a cut hole 9 in FIG. 2) having a diameter smaller than the diameter into which the transmission line 4 and others are inserted is provided. FIG. 1 shows only the upper half of the cross-sectional shape along the central axis, and the lower half is axisymmetric, but is omitted.

Such a pole piece 1 and a spacer 2
Using a centering jig, one convex portion and the other concave portion are fitted and alternately combined in the axial direction, and are air-tightly joined by, for example, brazing to form the vacuum envelope 3. The vacuum envelope 3 hermetically joined by the brazing material 10 as shown in FIG. 2 expands the diameter of the cut hole 9 by precise cutting until it reaches the size of the transmission line 4 and other insertion holes. By finishing the shape, the vacuum envelope 3 is completed. FIG. 3 shows a schematic cross-sectional view of the vacuum envelope 3 after finishing processing.

In the present embodiment, the pole piece 1 and the spacer 2 are provided with concave and convex shapes, respectively, and by combining these, a structure and a manufacturing method in which the axial deviation of the cutting hole 9 is hard to occur can be realized. Becomes

In this embodiment, when one pole piece and one spacer are fitted in principle, a centering jig can be made unnecessary. However, since components of about 2 mm are stacked up to a total length of about 100 mm, accumulated axial misalignment will inevitably occur. Therefore, to keep the deviation within the specified dimensions, use a centering jig as before.

In this embodiment, although the structure of the combination is changed, there is still a possibility that the conventional joining may occur due to the brazing material flowing into the space where the clearance between the jig and the pole piece is narrow. Non-metallic materials such as ceramics may be used for jigs as a method of preventing the inflow of brazing material.

[0013] Factors of the axis deviation include a combination shape,
There are machining accuracy for individual parts, accumulated misalignment due to combination of parts, and machining accuracy after brazing, etc., but in this embodiment, axis misalignment is reduced by devising the combination shape.

Embodiment 2 FIG. As a second embodiment, a case where a jig for assembling the vacuum envelope 3 is not required will be described as an example. By increasing the processing accuracy of the concave and convex portions of the pole piece 1 and the spacer 2, the fitting portion between the pole piece 1 and the spacer 2 can also serve as a centering jig. In this case as well, the same effects as in the first embodiment can be obtained, and the problem of joining to the jig does not occur because the centering jig is not required.

[0015] To improve the processing accuracy, it is possible to respond by preparing several types of processing jigs with different diameters, since the processed part is made of a material that is easy to cut. Processing accuracy (finish accuracy) is currently 5μ or less. Even if the processing accuracy of a single part is increased by this embodiment, the accumulated displacement due to the superposition will occur. Also, in the cutting process after brazing, the accuracy of machining the inner surface of a cylindrical shape made of a combination of different materials with a total length of about 100 mm is affected by the difference in material hardness, and causes axis misalignment.

Embodiment 3 Third Embodiment As a third embodiment, an example will be described in which the hole 9 for cutting is made of only the material of the spacer 2 when the pole piece 1 and the spacer 2 are fitted. FIG. 4 is a schematic cross-sectional view of the vacuum envelope 3 in the present embodiment at the time of hermetic joining. Also in this case, the same effect as in the above embodiment can be obtained, and since the inner diameter of the spacer 2 is smaller than the inner diameter of the pole piece 1, it is sufficient to cut only the spacer, and the cut hole 9 is made of the same material. As a result, unevenness in the cutting process hardly occurs, the cutting accuracy is increased, and the center axis deviation of the vacuum envelope 3 can be suppressed.

Axis misalignment is caused by the processing accuracy of a single component, the assembly accuracy, the cutting accuracy after assembly, and the like. In the present embodiment, a case is described in which deviation from cutting accuracy after assembly is prevented. If there are two types of materials on the machined surface, misalignment is likely to occur due to differences in material hardness. The solution is to eliminate the uneven cutting by using the same machined part. In the present embodiment,
By devising the combination shape, raising the precision of single-piece processing, and unifying the material of the cutting part, the axis deviation is reduced, so the centering jig is not required.

Embodiment 4 As a fourth embodiment, an example will be described in which the hole 9 for cutting is made of the material of the spacer 2 and the brazing material 10 when the pole piece 1 and the spacer 2 are fitted together. FIG. 5 is a schematic cross-sectional view of the vacuum envelope 3 in the present embodiment at the time of hermetic joining. In this case, since the inner diameter of the spacer 2 is smaller than the inner diameter of the pole piece 1, the spacer and the brazing material are cut, and the cut hole 9 is made of two kinds of materials, and the hardness at the time of cutting is different. However, since the hardness of the brazing material 10 is sufficiently smaller than that of the spacer 2 material, the cutting hardness is determined by the hardness of the spacer 2 material. Therefore, also in the present embodiment, the same effect as in the third embodiment can be obtained.

Embodiment 5 In the fifth embodiment, a case where the pole piece 1 and the spacer 2 are fitted together and the cutting hole 9 is made of only the pole piece 1 material or the pole piece 1 material and the brazing material 10 will be described as an example. Also in this case, the same effects as those of the third embodiment or the fourth embodiment can be obtained. However, in the present embodiment, since the pole piece 1 and the spacer 2 are also magnetic circuit forming parts of the traveling wave tube, the magnetic circuit is short-circuited if the material of the pole piece 1 is left uncut when the cut hole 9 is formed. Therefore, at the end of the cutting, the material surface of the spacer 2 must completely appear on the cut surface.

FIG. 6 is a schematic sectional view at the time of airtight joining. Since the inside diameter of the pole piece 1 is smaller than the inside diameter of the spacer 2, in the cutting after brazing, the processing holes 9 are made of the same material of the pole piece 1 alone, so that no processing unevenness occurs.
Therefore, no axial displacement occurs.

Embodiment 6 When the pole piece 1 and the spacer 2 are fitted, the hole 9 for cutting is
The case of the brazing material 10 will be described. FIG. 7 is a schematic cross-sectional view of the vacuum envelope 3 according to the present embodiment at the time of hermetic joining. Since the inside diameter of the pole piece 1 is smaller than the inside diameter of the spacer 2, the spacer and the brazing material are cut.
Although the cutting hole 9 is made of two kinds of materials and the hardness at the time of cutting is different, the hardness of the brazing material 10 is sufficiently smaller than that of the spacer 2, so the cutting hardness is determined by the hardness of the spacer 2. Therefore, the same effect as in the fifth embodiment can be obtained.

Embodiment 7 FIG. As a seventh embodiment, an example will be given in which, when the pole piece 1 and the spacer 2 are fitted together, the cutting hole 9 is a component used in any of the pole piece 1 and the spacer 2 using a material having a low cutting hardness. State. In this case as well, the same effects as in the above embodiment can be obtained, and the cutting work can be easily performed because the cutting hardness of the material to be processed is small. Further, even if the brazing material 10 is present in the cutting hole 9, the hardness of the brazing material 10 is sufficiently smaller than the material hardness of the cutting hole 9, so that the brazing material 10 does not affect the cutting operation.

Embodiment 8 FIG. As an eighth embodiment, in the vacuum envelope described in the first to sixth embodiments, the shape of both ends of the vacuum envelope after the cutting process is uneven, and the uneven shape is formed by a plurality of vacuum envelopes. The case of using for connection 3 will be described as an example. FIG. 8 is a schematic cross-sectional view when the vacuum envelope 3 according to the present embodiment is connected. Reference numeral 7 denotes a first vacuum envelope having a convex shape at the connecting portion. Reference numeral 8 denotes a second vacuum envelope having a concave shape at the connecting portion. A plurality of vacuum envelopes are connected in the axial direction by these uneven shapes. According to this embodiment, the effects obtained in the first to sixth embodiments can be similarly obtained by using the vacuum envelope 3 alone, and the shaft between the vacuum envelopes 3 generated when a plurality of vacuum envelopes 3 are connected. Deviation can be suppressed. Generally, after the cutting of each vacuum envelope is completed, a plurality of vacuum envelopes are connected. However, if the total length when the vacuum envelope is connected is about 100 mm or less, it is possible to perform cutting after the connection.

[0024]

As described above, according to the present invention, it is possible to suppress the misalignment of the vacuum envelope 3 by providing each of the pole piece 1 and the spacer 2 with a combination of concave and convex shapes. This eliminates the need for the centering jig described above, and has an effect of having a fitting function when the vacuum envelope 3 is connected, thereby suppressing axial misalignment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a pole piece and a spacer according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the vacuum envelope according to the first embodiment of the present invention at the time of hermetic joining.

FIG. 3 is a schematic sectional view of a vacuum envelope according to a first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a vacuum envelope according to a third embodiment of the present invention at the time of hermetic joining.

FIG. 5 is a schematic sectional view of a vacuum envelope according to a fourth embodiment of the present invention at the time of hermetic joining.

FIG. 6 is a schematic cross-sectional view of a vacuum envelope according to a fifth embodiment of the present invention at the time of hermetic joining.

FIG. 7 is a schematic sectional view of a vacuum envelope according to a sixth embodiment of the present invention at the time of hermetic joining.

FIG. 8 is a schematic cross-sectional view when a vacuum envelope according to an eighth embodiment of the present invention is connected.

FIG. 9 is a schematic sectional view of a conventional vacuum envelope.

FIG. 10 is a schematic sectional view of a conventional spiral slow wave circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pole piece 2 Spacer 3 Vacuum envelope 4 Transmission line 5 Support 6 Metal loading element 7 Vacuum envelope A 8 Vacuum envelope B 9 Cutting hole 10 Brazing material

Claims (3)

[Claims] 1. A method of manufacturing a vacuum envelope of a traveling wave tube by alternately joining a pole piece made of a ferromagnetic ring and a spacer made of a non-magnetic ring in an axial direction.
A pole piece having a joint having a convex portion and a joint having a concave portion, and a joint having a concave portion and a spacer having a joint having a convex portion are fitted with one convex portion and the other concave portion. A method for manufacturing a vacuum envelope for a traveling wave tube, comprising: a step of alternately joining in an axial direction; a step of hermetically joining the joint by brazing or welding; and a step of cutting a center hole. 2. The method for manufacturing a vacuum envelope of a traveling wave tube according to claim 1, wherein the inner diameter of the pole piece and the inner diameter of the spacer are made different. 3. The method for manufacturing a vacuum envelope of a traveling wave tube according to claim 1, further comprising a step of joining a plurality of envelopes in an axial direction.