DE2653361A1 - ELECTRIC ARC BURNER - Google Patents

Description

IAlISIAKWALT DIPL. ING. K. HOIiZER PHIliIPPIirK-WBLSBB-STBASBB 14

8900 AUGSBURG

TELBFOH 61β4-0 TBLEX 6S3S02 p * ioH

W. 831

Augsburg, November 18, 1976

BOC Limitedj Hammersmith House, London W6 9DX, England

Electric arc torch

The invention relates to an electric arc torch which has one at its front end with the torch head connected outer metal jacket and tubular supply lines extending through the interior of the jacket for supplying gas, water and electrical energy.

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The expression "arc torch ¹¹ " means a device in which an electric arc is generated between a torch electrode and either an electrically conductive workpiece or a second electrode metallurgical and chemical treatment of materials.

The invention relates particularly, but not exclusively, to direct arc plasma torches. The arc is usually created between a central replaceable electrode and the workpiece, wherein both the arc plasma and the plasma-forming gas flow through a mouthpiece that constricts the beam. It is also common practice to place a relatively low energy pilot arc between the central electrode and to produce the mouthpiece. If the workpiece is not electrically conductive, the arc burns between the central electrode and the mouthpiece.

The invention aims to provide an improved electric arc torch.

For this purpose, an electric arc torch is the initially mentioned type according to the invention, characterized in that the supply line by a

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Resin body formed between it and the jacket is electrically insulated from the jacket.

According to a further feature of the invention, the arc torch designed as a plasma torch has a replaceable central electrode that is in thermal and electrical contact with a first heat sink stands, and an annular mouthpiece, which is also in thermal and electrical contact with a second Heat sink is available, xro with each of the two heat sinks, a pipe bend of a tubular cooling water line is assigned and wherein the two heat sinks are electrically isolated from one another. Preferably serves at least a supply line as a feed line for the electrical Current.

In accordance with yet another feature of the invention, the inner end of the replaceable central electrode is rigid attached to a screw-threaded sleeve which is inserted into a threaded hole of a metal receiving body can be screwed in, which serves as a connection for an electrical conductor for supplying the arc current.

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The electric arc torch according to the invention is preferably a plasma torch or a torch with a constricted arc, in which the outer part of the mouthpiece is provided on its outer end surfaces with a ceramic layer or another heat and electrically insulating material layer and is surrounded by an annular screen made of electrically insulating material is.

The invention is described in more detail below with reference to the accompanying drawing, for example, which shows a section through an arc torch according to the invention with a constricted arc.

The central electrode 2 of the burner is made of tungsten or some other permanent metal and is connected at its inner end to a sleeve 4 which has a flange 6 and a part 8 provided with a screw thread. The sleeve 4 can be screwed into a threaded bore of a connection piece 10, which also serves as a heat sink. The connector is surrounded by a line loop of a tubular line 12, which is hard or soft soldered to the connector 10, so that there is only a low electrical and thermal resistance between the line und.der electrode 2 and the heat easily from the

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Electrode 2 can pass over to line 12. The ends of the line are at a point away from the burner on the one hand with a cooling water source or a drain for the consumed water and on the other hand connected to a connection of an electrical energy source.

The connection piece 10 is suitable from a further connection piece 18 through an insulating body 20 electrically insulating material separated. The insulating body is approximately ring-shaped and encloses a chamber 16. The wall the chamber 16 is formed by a sleeve 39 made of electrically insulating, heat-resistant material, which is exchangeable.

The connector 10 is also with one end of a line 14 in connection with the supply of argon or Another suitable gas for plasma formation is used, which through a channel or channels in the connector 10 and the Insulating body 20 enters chamber 16.

Similar to the connection piece 10, the connection piece 18 is from a line loop of a further tubular Enclosed line 22, which is used to supply cooling water and electrical energy. The connector 18 is on one outer annular and interchangeable mouthpiece 24 attached,

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whose inner diameter is graduated at 26 so that the plasma gas flow through the space between the Electrode and mouthpiece 24 is constricted · The ends of lead 22 are at one remote from the torch Place with a source of cooling water or a drain for the used water and the other connection of the already electrical energy source connected.

The outer surface of the mouthpiece 24 is coated with a layer 28 of ceramic material to provide a to prevent accidental short circuits caused by contact between the mouthpiece and an electrically conductive workpiece.

An outer, screw-threaded sleeve 30, for example soft, is attached to the connecting piece 18 soldered onto which an internally threaded screen 32 made of electrically insulating material is screwed is. It can be seen that the ceramic layer 28 and the screen 32 cooperate with one another in such a way that the Risk of contact between any electrically conductive part of the torch and the workpiece or chips or other conductive particles is minimized as a result of a performed by means of the plasma torch Metal processing arise.

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In addition, gases can in a not shown chamber between the screen 20 and the connection piece 18 with With the aid of a likewise not shown, on the connection piece 18 soft soldered line are introduced, which runs along the line 22 to the burner head.

The insulating body 20 is attached to one end of a metal jacket 3 ^, which is preferably made of stainless steel and can be straight, curved or angled. At the end facing away from the electrode arrangement, an inner sleeve 36 made of an electrically insulating material engages in the metal jacket 3 ^. The lines 12 and 22 and the gas line Ik run with clearance through the interior of the sleeve 3 £.

According to a feature of the invention, the space between the sleeve 36, the jacket 3 ^, the lines 12, 22 and l4 and the connector 10 and the insulating body filled with a suitable casting compound, i.e. a synthetic resin, which hardens after being poured into the space mentioned is. After curing, the resulting synthetic resin body 38 serves to protect the internal parts of the burner against vibrations and shocks and thus leads to a longer service life of these parts. To make this Synthetic resin body no complicated and expensive casting tools are required. Alternatively, the synthetic resin

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body 38 made of suitable insulating material will.

The separate cooling of the connecting pieces 10 and 18 and the fact that the cooling water circuits are only connected to one another at a point remote from the burner prevents electrolytic corrosion within the burner. The use of two tubular lines within the burner also simplifies the flow of cooling water. There occur no abrupt changes in cross-sectional area or flow direction and no gap-shaped spaces exist in which dirt can collect.

The annular electrode or the mouthpiece 24 is screwed into the connecting piece 18 or inserted into it in some other way. As a result, the electrode 24 can be removed when the central electrode 2 is to be inserted or replaced. After the electrode 24 has been removed, the arrangement formed by the electrode 2 and the sleeve can be inserted into the chamber 16 by means of a socket wrench or another suitable tool and screwed into the connecting piece 10.

With conventional plasma or TIG torches , the

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central electrode usually by means of a collet held. This means that the electrode can be removed from time to time for post processing and adjustment will. This means that the position of the electrode is checked and adjusted every time it is reinserted got to. The way in which the electrode is inserted and held in the arrangement according to the invention makes the adjustment work the middle electrode can be dispensed with, since the setting is automatically determined by the sleeve 4, so that none There is a possibility of a misalignment. There is also no possibility of adjusting the electrodes Compensation for wear, but this disadvantage is far less important than the advantage of the worker to relieve the fact that a variable is taken out of its control area. In practice it will the front end of the central electrode is shaped and treated so that the electrode has a satisfactory service life achieved.

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Claims (10)

Claims Iy Electric arc torch, the one on his front end connected to the burner head outer metal jacket and extending through the interior of the jacket having tubular supply lines for the supply of gas, water and electrical energy, thereby characterized in that the supply lines (12, 14, 22) are formed by one between them and the jacket (34) Resin body (38) are electrically isolated from the jacket. 2. Arc torch according to claim 1, characterized in that the synthetic resin body (38) consists of a the entire free space within the jacket (34) - * filling, poured and hardened casting compound. 3. Plasma torch type arc torch, with a replaceable central electrode, which is in thermal and is in electrical contact with a first heat sink, and with an annular mouthpiece associated with a second heat sink is in thermal and electrical contact, characterized in that each heat - 10 - 709821/0787 arrester (10, l8) a line loop of a separate Cooling water line (12, 22) is assigned, and that both Heat sinks are electrically isolated from each other. 4. Arc torch according to claim 3 _9, characterized in that at least one of the cooling water lines serves as an electrical power supply. 5. arc torch according to claim 3 or 4, characterized in that each heat sink (10, 18) of one Wrap of the relevant cooling water line (12, 22) enclosed that is soldered soft or hard to the heat sink. 6. arc torch according to one of claims 3 to p, characterized in that both cooling water lines (12, 22) serve as electrical leads. 7ο arc torch according to one of claims 3 to 6, characterized in that the annular dog piece (24) is removably attached to the second heat sink (18). 8. arc torch with a replaceable central electrode, characterized in that the ineffective - 11 - 709821/0787 üinde of the central electrode (2) is rigidly attached to an externally _{threaded sleeve (4) 9} which in turn can be screwed into a threaded hole of a metal receiving body (10) serving as a connection for a power supply line (12). 9. Arc torch according to claim 8, which is designed as a plasma torch, characterized in that that the receiving body (10) is connected to the end of a supply line (14) for supplying a plasma-forming gas, and that one or more channels in the receiving body conduct the gas into a chamber (16) from which it to a ring-shaped mouthpiece (2 4), which has a constricted exit opening .to constrict the plasma beam having. 10. Liehtbogenbrenner- according to one of claims 3 to or 9 » characterized in that the outer part of the mouthpiece (24) is coated on its outer surfaces with a layer (28) of ceramic or other electrically insulating material and of an annular screen (32 ) is surrounded by electrically insulating material. - 12 - 709821/0787