GB2094200A

GB2094200A - Electron beam apparatus for effecting an annular weld

Info

Publication number: GB2094200A
Application number: GB8105923A
Authority: GB
Original assignee: GRAHAM MANUFACTURING Ltd
Current assignee: GRAHAM MANUFACTURING Ltd
Priority date: 1981-02-25
Filing date: 1981-02-25
Publication date: 1982-09-15

Abstract

A heat exchanger tube (1) is welded to a tube plate (2) by an electron welding beam from a source (4). The source (4) is accommodated in a chamber (5) and is constructed to emit a frusto-conical welding beam. The tube (1) is blocked by an expansible plug (14) and the wall of the chamber (5) is sealed to the tube plate (2), so that the chamber (5) can be evacuated. After evacuation, the source (4) is actuated to perform the welding operation. <IMAGE>

Description

SPECIFICATION Welding This invention relates to securing members together by welding.

A particular application of welding is in connecting heat exchanger tubes, at their ends, to tube plates (also known as tube sheets) where the use to which the heat exchanger is to be put requires a good permanent seal between the tubes and the tube plates. Such welding can be carried out by the well-known argon arc process but if handheld welding equipment is utilised a skilled operator is required and the operation is lengthy as two welding passes may be required around each tube end to ensure a good joint. Equipment is available that can be mounted on each tube end in turn and operated so that welding is effected automatically but skill is still required accurately to set up the equipment on each tube and monitor its operation, and the equipment is complex as it has to operate to perform welding passes around the tubes.

According to the present invention there is provided a welding assembly for welding a hollow member to a further member at a zone at which the hollow member is entered in an aperture in the further member; the welding assembly comprising an electron welding beam, source mounted within a chamber for providing an electron welding beam directed at a zone of closed loop formation within the periphery of an aperture in a wall of the chamber; the chamber carrying seals whereby it can be mounted in gas-tight fashion on said members, these seals comprising a plunger supported through said aperture and sealingly engageable within the hollow member, and a seal around the aperture outboard of the aperture that is sealingly engageable with the further member; the assembly further including means for evacuating the chamber when it is sealed to said members, and means for energising said source to produce said beam to weld the two members together at said zone of enclosed loop formation. Such an assembly can be quickly and easily fitted onto the members to be welded together, and as no components have to be moved relative to the members whilst welding is effected a minimum of moving parts has to be provided and the time taken to effect welding is also minimised.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompaying drawing, in which the single Figure is a diagrammatic sectional side view of a welding assembly, shown mounted on a hollow heat exchanger tube and a tube plate to which the tube is to be welded.

In the Figure the heat exchanger tube is referenced 1 and the tube plate is referenced 2. The welding assembly is referenced 3. This assembly consists of any annular electron beam welding source 4 of anode/cathode form mounted within a chamber 5 and having a power supply lead 6 passed through insulators 7. The chamber 5 is in two parts 5A, 5B that are interconnected by a screw coupling 8, the source 4 being carried by the part 5A and being arranged to produce, when energised, a frustoconical welding beam 9 directed at an annular zone 9A within the periphery of an aperture 10 in a base wall 11 of the chamber part 5B. The diameter of the beam at the zone 9A can be selected by adjusting the relative positions of the two parts 5A, 5B utilising the screw coupling 8.

As shown in the Figure, to effect welding the chamber 5 is mounted in gas-tight fashion on the tube 1 and tube plate 2. To this end, a shaft 12 mounted in gas-tight manner in the chamber wall 13 that is opposed to the wall 11 extends through the aperture 10 and carries, outside the chamber 5, a plunger in the form of an expansible rubber plug 14.

This plug 14 is entered in the tube 1, the diameter of the plug 14 being expanded by operation of an inner shaft 12A, after the plug has entered the tube, such that the plug becomes sealingly engaged in the tube.

In addition, an annular seal 15 around the aperture 10 seals on the plate 2. The chamber 5 is then evacuated via a port 16 and the electron beam welding source 4 is energised to effect welding at the zone 9A.

It will be understood that the welding is effected by a glow discharge electron beam and it can be arranged that the equipment is automatically triggered to effect welding by actuation of a swich as the assembly 3 is located on the parts to be welded together. Once located, welding is effected without relative motion of parts within the assembly and is therefore speedily effected.

It will be appreciated that whilst the welding of heat exchanger tubes to tube plates has been specifically described, other members could be welded together, by equipment such as has been described, where a weld of closed loop formation is required around a hollow member.

CLAIMS (Filed on 23 Feb 1982) 1. A welding assemblyforwelding a first member to a second member at a zone where the first member is entered in an aperture in the second member, the welding assembly comprising an electron welding beam source mounted within a chamber for providing an electron welding beam directed at a welding zone of closed loop formation within the periphery of an opening wall of the chamber, the wall of the chamber being adapted to make gas-tight engagement with the second member in a zone surrounding the opening, the assembly further comprising means for enabling the chamber to be evacuated when the wall of the chamber is in gas-tight engagement with the second member, and means for energizing the electron welding beam source to produce the beam to weld the two members together at the welding zone.

2. A welding assembly as claimed in claim 1,for use where the first member is hollow, in which blocking means is provided for blocking the first member in a gas-tight fashion.

3. A welding assembly as claimed in claim 2, in which the blocking means comprises a plunger which extends from the chamber through the open

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

SPECIFICATION Welding This invention relates to securing members together by welding.

A particular application of welding is in connecting heat exchanger tubes, at their ends, to tube plates (also known as tube sheets) where the use to which the heat exchanger is to be put requires a good permanent seal between the tubes and the tube plates. Such welding can be carried out by the well-known argon arc process but if handheld welding equipment is utilised a skilled operator is required and the operation is lengthy as two welding passes may be required around each tube end to ensure a good joint. Equipment is available that can be mounted on each tube end in turn and operated so that welding is effected automatically but skill is still required accurately to set up the equipment on each tube and monitor its operation, and the equipment is complex as it has to operate to perform welding passes around the tubes.

According to the present invention there is provided a welding assembly for welding a hollow member to a further member at a zone at which the hollow member is entered in an aperture in the further member; the welding assembly comprising an electron welding beam, source mounted within a chamber for providing an electron welding beam directed at a zone of closed loop formation within the periphery of an aperture in a wall of the chamber; the chamber carrying seals whereby it can be mounted in gas-tight fashion on said members, these seals comprising a plunger supported through said aperture and sealingly engageable within the hollow member, and a seal around the aperture outboard of the aperture that is sealingly engageable with the further member; the assembly further including means for evacuating the chamber when it is sealed to said members, and means for energising said source to produce said beam to weld the two members together at said zone of enclosed loop formation. Such an assembly can be quickly and easily fitted onto the members to be welded together, and as no components have to be moved relative to the members whilst welding is effected a minimum of moving parts has to be provided and the time taken to effect welding is also minimised.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompaying drawing, in which the single Figure is a diagrammatic sectional side view of a welding assembly, shown mounted on a hollow heat exchanger tube and a tube plate to which the tube is to be welded.

In the Figure the heat exchanger tube is referenced 1 and the tube plate is referenced 2. The welding assembly is referenced 3. This assembly consists of any annular electron beam welding source 4 of anode/cathode form mounted within a chamber 5 and having a power supply lead 6 passed through insulators 7. The chamber 5 is in two parts 5A, 5B that are interconnected by a screw coupling 8, the source 4 being carried by the part 5A and being arranged to produce, when energised, a frustoconical welding beam 9 directed at an annular zone 9A within the periphery of an aperture 10 in a base wall 11 of the chamber part 5B. The diameter of the beam at the zone 9A can be selected by adjusting the relative positions of the two parts 5A, 5B utilising the screw coupling 8.

As shown in the Figure, to effect welding the chamber 5 is mounted in gas-tight fashion on the tube 1 and tube plate 2. To this end, a shaft 12 mounted in gas-tight manner in the chamber wall 13 that is opposed to the wall 11 extends through the aperture 10 and carries, outside the chamber 5, a plunger in the form of an expansible rubber plug 14.

This plug 14 is entered in the tube 1, the diameter of the plug 14 being expanded by operation of an inner shaft 12A, after the plug has entered the tube, such that the plug becomes sealingly engaged in the tube.

In addition, an annular seal 15 around the aperture 10 seals on the plate 2. The chamber 5 is then evacuated via a port 16 and the electron beam welding source 4 is energised to effect welding at the zone 9A.

It will be understood that the welding is effected by a glow discharge electron beam and it can be arranged that the equipment is automatically triggered to effect welding by actuation of a swich as the assembly 3 is located on the parts to be welded together. Once located, welding is effected without relative motion of parts within the assembly and is therefore speedily effected.

It will be appreciated that whilst the welding of heat exchanger tubes to tube plates has been specifically described, other members could be welded together, by equipment such as has been described, where a weld of closed loop formation is required around a hollow member.

CLAIMS (Filed on 23 Feb 1982)

1. A welding assemblyforwelding a first member to a second member at a zone where the first member is entered in an aperture in the second member, the welding assembly comprising an electron welding beam source mounted within a chamber for providing an electron welding beam directed at a welding zone of closed loop formation within the periphery of an opening wall of the chamber, the wall of the chamber being adapted to make gas-tight engagement with the second member in a zone surrounding the opening, the assembly further comprising means for enabling the chamber to be evacuated when the wall of the chamber is in gas-tight engagement with the second member, and means for energizing the electron welding beam source to produce the beam to weld the two members together at the welding zone.

2. A welding assembly as claimed in claim 1,for use where the first member is hollow, in which blocking means is provided for blocking the first member in a gas-tight fashion.

3. A welding assembly as claimed in claim 2, in which the blocking means comprises a plunger which extends from the chamber through the open ing and is sealingly engageable with the first member.

4. A welding assembly as claimed in claim 3, in which the plunger comprises an expansible, resilient plug for entry into the first member and sealing engagement therewith.

5. A welding assembly as claimed in any one of the preceding claims, in which the wall of the chamber is provided with a sealing ring surrounding the opening for effecting a gas-tight seal with the second member.

6. A welding assembly as claimed in any one of the preceding claims, in which the welding beam source is annular and is adapted to produce a frusto-conical welding beam.

7. A welding assembly as claimed in any one of the preceding claims, in which the wall of the chamber comprises two parts which are interconnected by a screw coupling.

8. A welding assembly as claimed in claim 7, in which operation of the screw coupling adjusts the diameter of the welding zone.

9. A welding assembly substantially as described herein with reference to, and as shown in, the accompanying drawing.

10. Amethod of welding a heatexchangertube to a tube plate using a welding assembly in accordance with any one of the preceding claims.

11. A heat exchanger comprising tubes which are welded to tube plates by a method in accordance with claim 10.

New claims or amendments to claims filed on 30.3.82 Superseded claim 1 New claim:- 1 Original claim 6 deleted, original claims 7-11 renumbered and appendenix coorespondingly corrected

1. A welding assembly for welding a first member to a second member at a zone where the first member is entered in an aperture in the second member, the welding assembly comprising an annular elctron welding beam source mounted within a chamber for providing a frusto-conical electron welding beam directed at a welding zone of closed loop formation within the periphery of an opening wall of the chamber, the wall of the chamber being adapted to make gas-tight engagement with the second member in a zone surrounding the opening, the assembly further comprising means for enabling the chamber to be evacuated when the wall of the chamber is in gas-tight engagement with the second member, and means for energizing the electron welding beam source to produce the beam to weld the two members together at the welding zone.