Method for producing an electrical bushing

Abstract

A method for producing an electrical bushing with a multi-part inner conductor arranged at least in some sections in an outer tube made from metal and electrically insulated from the outer tube by an electrically insulating material. The inner conductor of the finished bushing has at least one contact section protruding out of the outer tube and a bearing section that is arranged within the outer tube and that is compressed with the electrically insulating material. The outer tube made from metal to form a composite for supporting the at least one contact section. The at least one contact section and the bearing section compressed with the electrically insulating material and the outer tube made from metal to form the composite for supporting the at least one contact section are prepared as separate assemblies and then connected to each other.

Claims

1. A method for producing an assembly of an electrical bushing with a multi-part inner conductor at least partially arranged within an outer tube made from metal, the multi-part inner conductor having at least one contact section made from metal and a discrete bearing section, the method comprising: arranging an electrically insulating material within the outer tube; arranging the bearing section within the outer tube, whereby the electrically insulating material is interposed therebetween; radially compressing the outer tube and the electrically insulating section upon the bearing section therein, thereby forming a composite to support the at least one contact section; and at least partially inserting the at least one contact section within the bearing section of the composite.

2. The method according to claim 1, wherein the at least one contact section is supported without contact to the electrically insulating material in the bearing section.

3. The method according to claim 1, wherein connecting the at least one contact section to the bearing section compressed with the electrically insulating material and the outer tube made from metal for supporting the at least one contact section is carried out such that an elongation or an at least partial structural change of the at least one contact section is prevented.

4. The method according to claim 1, wherein the method after preparing the at least one contact section has no method steps in which the structure of the at least one contact section is changed.

5. A method for producing an assembly of an electrical bushing with an inner conductor arranged at least in some sections in an outer tube made from metal and electrically insulated from the outer tube by an electrically insulating material, wherein the inner conductor of the electrical bushing has at least one contact section protruding out of the outer tube made from metal and a bearing section that is arranged within the outer tube and that is compressed with the electrically insulating material and the outer tube made from metal to form a composite for supporting the at least one contact section, wherein in the method, the at least one contact section and the bearing section compressed with the electrically insulating material and the outer tube made from metal to form the composite for supporting the at least one contact section are prepared as separate assemblies and then connected to each other, wherein providing the assembly with the bearing section compressed with the electrically insulating material and the outer tube made from metal to form a composite includes the step of separating a section of a compressed bar material made from a metallic inner part, the electrically insulating material, and the outer tube, so that the bearing section is formed from the metallic inner part.

6. The method according to claim 5, wherein the at least one contact section is welded or soldered to one end side of the metallic inner part forming the bearing section.

7. The method according to claim 5, wherein providing the assembly with the bearing section compressed with the electrically insulating material and the outer tube made from metal to form the composite also has the step of forming at least one opening in the metallic inner part forming the bearing section.

8. The method according to claim 7, wherein the at least one opening is formed in the metallic inner part forming the bearing section so that the at least one opening passes completely through the metallic inner part, the at least one contact section is pushed into the at least one opening so that the at least one contact section protrudes out of the at least one opening on both sides of the metallic inner part, and the at least one contact section is fixed in the at least one opening such that the assembly made from the at least one contact section is sealed with the bearing section fixed therein.

9. The method according to claim 7, wherein the at least one opening is formed as a blind hole in the metallic inner part forming the bearing section and one end of the at least one contact section is pushed into the blind hole and fixed therein.

10. The method according to claim 7, wherein the at least one opening is formed concentric to a center axis of the outer tube.

11. The method according to claim 5, wherein before connecting the at least one contact section to the bearing section, a position of the bearing section relative to the outer tube is determined and the determination is used for positioning the at least one contact section.

12. The method according to claim 5, wherein for providing the assembly with the bearing section compressed with the electrically insulating material and the outer tube made from metal to form the composite, a tubular metallic inner part is compressed with the electrically insulating material and the outer tube made from metal so that the bearing section is formed from the tubular metallic inner part.

13. The method according to claim 12, wherein during the compression of the tubular metallic inner part with the outer tube and the electrically insulating material to form the composite, an interior of the tubular metallic inner part is filled with a core that is removed from the interior after the compression.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the preferred invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

(2) FIG. 1a is a cross-sectional view of a first intermediate stage in the preparation of an assembly for the bushing of a method according to the preferred invention,

(3) FIG. 1b is a cross-sectional view of a second intermediate stage in the preparation of the assembly for the bushing of FIG. 1a,

(4) FIG. 2a is a side elevational, partial cross-sectional view of a step in producing a first electrical bushing with the method according to the preferred invention,

(5) FIG. 2b is a cross-sectional view of the electrical bushing produced by the preferred method,

(6) FIG. 3a is a side elevational, partial cross-sectional view of a step in producing a second electrical bushing with the method according to the preferred invention,

(7) FIG. 3b is a side elevational, partial cross-sectional view of the electrical bushing produced by the preferred method,

(8) FIG. 4a is a side elevational, partial cross-sectional view of a step in producing a third electrical bushing with the method according to the preferred invention,

(9) FIG. 4b is a cross-sectional view of the electrical bushing produced by the preferred method,

(10) FIG. 5a is a side elevational, partial cross-sectional view of a step in producing a fourth electrical bushing with the method according to the preferred invention,

(11) FIG. 5b is a side elevational, partial cross-sectional view of the electrical bushing produced by the preferred method, and

(12) FIG. 6 is a side elevational, partial cross-sectional view of a sixth electrical bushing that can be produced with a method according to the preferred invention.

DETAILED DESCRIPTION OF THE INVENTION

(13) As can be seen from FIGS. 2a,b, 3a,b, 4a,b, 5a,b and 6, it is preferred for the method according to the invention that the respective electrical bushings 20, 30, 40, 50, 60 and especially their inner conductor is assembled from at least two separate assemblies, namely at least one contact section 21, 31a, 31b, 41, 51a, 51b, 61a, 61b as a first assembly and a bearing section 24, 34, 44, 54, 64 compressed with electrically insulating material 22, 32, 42, 52, 62 and an outer tube 23, 33, 43, 53, 63 made from metal to form a composite and arranged completely within the outer tube 22, 33, 43, 53, 63 made from metal for supporting the at least one contact section 21, 31a, 31b, 41, 51a, 51b, 61a, 61b as a second assembly, which is referred to collectively below as “bearing assembly.”

(14) For preparing the bearing assembly, as can be seen, in particular, from FIGS. 1a and 1b, a bar material 1 can be used that was produced by compressing a metallic inner part 3 held in the interior of an outer tube 2 made from metal and electrically insulated from this outer tube by an electrically insulating material 4, for example, by molded parts made from magnesium oxide, magnesium oxide powder or magnesium oxide granulate.

(15) The metallic inner part, which is used later for forming the bearing section 24, 34, 44, 54, 64 of the inner conductor of the electrical bushing 20, 30, 40, 50, 60, can be solid; however, in the embodiments shown in FIGS. 1a and 1b, the metallic inner part 3 has a tubular design and is filled with a core 5, in order to guarantee dimensional stability during the compression step, which must be performed at a high pressure, so that the porosity of the electrically insulating material 4 is sufficiently reduced. The core 5 is not required in all cases; just the use of a tubular metallic inner part might be sufficient.

(16) The simplest bearing assembly used in the embodiment of the electrical bushing 60 as per FIG. 6 is produced simply by cutting a section of the required length from the bar material 1, which is here performed with the tool 9. The separately produced contact sections 61a, 61b can then be welded or soldered on both sides to the end sides at solder or weld spots 65a, 65b to the bearing section 64, which is formed simply by the metallic inner part 3 which in this embodiment has a preferably not tubular but solid construction.

(17) Here, in the example of the electrical bushing shown, when the bearing assembly was prepared, the metallic inner part 3 became offset during the production of the bar material, and this offset caused the inner part to be asymmetric relative to the center axis of the outer tube 63 and that the thickness of the electrically insulating material 4 is different in different directions. The separately produced contact sections 61a, 61b, however, are centered relative to the outer tube 63 made from metal.

(18) In principle, such an offset can also be present in all other subsequently described embodiments and compensated during the connection of the respective contact sections 21, 31a, 31b, 41, 51a, 51b, 61a, 61b and the respective bearing assembly 20, 30, 40, 50, 60.

(19) To realize the bearing assembly used in the embodiment of the electrical bushing 20 as per FIGS. 2a and 2b, an opening 6 must be formed in the metallic inner part 3, as shown in FIGS. 1a and 1b, before cutting off a section 1a of the bar material 1 using the tool 9, in order to form the bearing section 24, for example, as shown in FIG. 1a with a drill 8 to a depth that is greater than the desired length of the bearing assembly. In this process, any core 5 that is present can also be drilled out at the same time. When forming the opening 6, this should preferably be centered relative to the outer tube 2.

(20) As shown in FIG. 2a, 2b, a separately produced contact section 21 can then be easily inserted into the bearing assembly and connected to this, for example, by a solder ring 25. However, it is important that the annular gap between the contact section 21 and the bearing section 24 is sealed sufficiently by the solder ring 25 so that the leakage rate is sufficiently low for the planned application.

(21) If such problems are to be avoided, a construction of the bearing assembly as shown in FIGS. 3a and 3b is possible. In this design, openings are formed in the metallic inner part 3 for forming the bearing section from both sides in such a way that a partition wall made from the material of the metallic inner part 3 remains between them. This can be realized either after cutting off a piece of the desired length from the bar material 1 from both sides or from one side before the cutting and from the other side after the cutting. Then the separately produced assemblies in the form of the contact sections 31a, 31b are inserted into these openings and fastened with solder rings 35a, 35b.

(22) The electrical bushing 40 shown in FIGS. 4a and 4b differs from the electrical bushing 20 of FIGS. 2a and 2b with respect to the bearing assembly and the type of fastening of the contact section 41 in the bearing section 44, which is made possible by the other bearing assembly. Here, during the preparation of the bearing assembly, a narrow ring of the outer tube and the electrically insulating material 4 is removed, e.g., machined, on both ends, so that a weld lip is produced on both sides on the end of the bearing section 44, on which a welded connection 46a, 46b is produced. Here, care must also be taken to ensure that the welded connections 46a, 46b guarantee the tightness of the annular gap. It can be seen immediately that the contact surface(s) of the bearing section 44, by means of which the electrical contact between the contact section 41 and the bearing section 44 protrude at most partially from the outer tube 43, so that the bearing section 41 is arranged in the sense of this description within the outer tube 43.

(23) The electrical bushing 50 shown in FIGS. 5a and 5b differs from the electrical bushing 30 of FIGS. 3a and 3b with respect to the bearing assembly and the type of fastening of the contact section 51 in the bearing section 54, which is made possible by the other bearing assembly. As in the embodiment of FIGS. 4a and 4b, a narrow ring of the outer tube 2 and the electrically insulating material 4 is also removed, e.g., trimmed, here at both ends during the preparation of the bearing assembly, so that a weld lip at which a welded connection 56a, 56b is generated is produced on both sides at the end of the bearing section 54.

(24) It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

LIST OF REFERENCE SYMBOLS

(25) 1 Bar material 3 Metallic inner part 5 Core 20,30,40,50,60 Electrical bushing 21,31a,31b,41,51a,51b,61a,61b Contact section 4,22,32,42,52,62 Electrically insulating material 2,23,33,43,53,63 Outer tube 24,34,44,54,64 Bearing section 25,35a,35b Solder ring 46a,46b,56a,56b Welded connection 65a,65b Solder or weld spot A Center axis of the outer tube