Electric heating – Metal heating – By arc
Patent
1997-10-17
1999-06-01
Paschall, Mark
Electric heating
Metal heating
By arc
219119, 219 75, B23K 1000
Patent
active
059085673
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electrode for a plasma arc torch.
BACKGROUND ART
A plasma arc torch is generally utilized for metal workings including cutting, welding, surface treating, dissolving and annealing Workings. As such plasma arc torch, one for the metal cutting working generally has a structure, for example, shown in FIG. 1.
In FIG. 1, reference numeral 13 denotes a torch body, reference numeral 1a is an electrode holder supported by the torch body 13, and reference numeral 1 is an electrode member embedded in and and joined to the electrode holder 1a. Reference numeral 2 is a nozzle supported by the torch body 13 through a nozzle supporting member 3 so as to surround the electrode member 1 and be positioned on a front end side of the electrode member 1, reference numeral 4 is a nozzle cap supported by the torch body 13, surrounding the nozzle 2 except the front end portion thereof and having a front end secured to the front end portion of the nozzle 2, and reference numeral 5 is a nozzle protecting cap supported by the torch body 13 and surrounding the outer side of the nozzle cap 4.
A plasma gas passage 6 is formed to a peripheral portion of the electrode member 1 so as to communicate with the nozzle 2 from this peripheral portion, and a cooling water passage 7 is further formed between the nozzle 2 and the nozzle cap 4. Still furthermore, a secondary gas passage 8 is formed between the nozzle cap 4 and the nozzle protecting cap 5 so as to open to the front end side of the nozzle 2.
The nozzle protecting cap 5 is in an electrically insulated from the nozzle cap 4.
The electrode body 1a is formed with a cooling water chamber 9 for cooling the electrode member 1, and the cooling water chamber 9 communicates with the cooling water passage 7. The cooling water chamber 9 is connected to a cooling water flow-in passage 10 and the cooling water passage 7 is connected to a cooling water flow-out passage 10a. On the other hand, a plasma gas flow-in passage 11 is connected to the plasma gas passage 6 and a secondary gas flow-in passage 12 is also connected to the secondary gas passage 8.
The torch body 13 serves to support the respective members and portions mentioned above and is electrically insulated from the electrode member 1 and the nozzle 2, and the nozzle protecting cap 5 is screw engaged with the torch body 13.
The electrode member 1 used for such plasma arc torch is formed of, in consideration of durability under a high temperature condition, a heat resistant material of homologous element such as hafnium (Hf), zirconium (Zr), titanium (Ti), etc., and the electrode member 1 is joined to the electrode body 1a formed of copper (Cu) by means of brazing.
The joining of the electrode member 1 to the electrode body 1a will be performed, by a method other than the brazing, as disclosed in the Japanese Patent Publication No. HEI 5-70250 teaching a technique that a sleeve made of such as silver is inserted into the electrode body 1a and the electrode member 1 is then inserted into the sleeve and fixed thereto. In this structure, however, surfaces to be joined of both the electrode member 1 and electrode body 1a have irregularity, which will constitute heat conduction resistance, thus being inconvenient.
In order to obviate this defect, when the electrode member 1 and the electrode body 1a are joined by means of brazing, the irregular surfaces are embedded with a brazing material, providing an excellent heat conduction performance therebetween and providing an improved cooling effect even if the electrode member 1 is formed of hafnium having a bad heat conduction property.
According to such fact, as mentioned above, the electrode member 1 is joined to the electrode body 1a by means of brazing and a silver (Ag) material is used as a brazing material including copper (Cu) of from several % to several tens % to lower a melting point thereof.
FIG. 2 shows a condition of a joined portion in a case where the hafnium electrode body 1 is the copper electrode body 1a by using a brazing m
REFERENCES:
patent: 3930139 (1975-12-01), Bykhovsky et al.
patent: 5097111 (1992-03-01), Severance, Jr.
patent: 5200594 (1993-04-01), Okada et al.
patent: 5330097 (1994-07-01), Inoue
patent: 5451739 (1995-09-01), Nemchinsky et al.
patent: 5676864 (1997-10-01), Walters
Sakuragi Shun-ichi
Tsurumaki Naoya
Komatsu Ltd.
Paschall Mark
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