EP0256525A1
Expired / Lapsed
EP
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Method of and apparatus for conducting plasma welding
Assignee: Hitachi Ltd
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Filing: 1987-08-13
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Granted: —
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Expires: 2007-08-13
Abstract
Abstract A plasma welding method has successive steps including pre-heating of members (15, 16) to be welded, tack welding of the for the members (15, 16) for tentatively fixing these members (15, 16), keyhole welding for completely welding the members (15,16) to each other, and finish padding. These steps are automatically conducted by a single plasma welding apparatus operative in accordance with a programmed sequence including data concerning the optimum conditions of operation in each step in relation to the conditions such as sizes and materials of the members (15,16) to be welded. The apparatus has a welding torch (7), a welding head on which the welding torch (7) is mounted for rotation, a controller (5) adapted for storing the optimum welding conditions for successive steps of the welding process in relation to the conditions of the members (15,16) to be welded, a power supply system (1) for transmitting welding current and welding speed signal to the welding head (6) in accordance with a command provided by the controller (1), and a gas supply system (11,14a,18) for supplying a plasma gas at a rate determined in accordance with a command from the controller (5).
Inventors
- 👤 Takashi Yamade
- 👤 Seishi Watahiki
- 👤 Yasuzi Sakuma
- 👤 Masayoshi Yamaguchi
- 👤 Shinichi Kurita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 18:08
CPC Classifications
B; B23; B23K; B23K10/00; B23K10/02; B23K9/00; B23K9/16; B23K9/167
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
61 words
A plasma welding method in which members to be welded to each other are placed in abutting relation to each other and tack-welded together so as to be tentatively fixed to each other before they are welded by plasma welding, characterized in that the tack welding is automatically conducted by means of plasma in accordance with the conditions of said members.
Claim 2
Dependent Claim
61 words
A plasma welding method in which members to be welded to each other are placed in abutting relation to each other and tack-welded together so as to be tentatively fixed to each other before they are welded by plasma welding, characterized in that the tack welding is automatically conducted by means of plasma in accordance with the conditions of said members.
Claim 3
Dependent Claim
55 words
A plasma welding method according to Claim l, further comprising the steps of: conducting, after the tack-welding step, keyhole welding by plasma welding method automatically in accordance with the conditions of said members; and conducting, after the keyhole welding step, finish padding by plasma welding method automatically in accordance with the conditions of said members.
Claim 4
Dependent Claim
34 words
A plasma welding method according to Claim l, further comprising the step of conducting, in advance of the tack-welding step, pre-heating of the weld portions of said members automatically by means of a plasma.
Claim 5
Dependent Claim
55 words
A plasma welding method according to Claim l, wherein the tack-welding step is conducting while restricting the welding current, plasma gas flow rate and shield gas flow rate in accordance with the sizes of said members to be welded and controlling the welding speed in accordance with the sizes of said members to be welded.
Claim 6
Independent Claim
54 words
A method according to Claim l, wherein the tack-welding step is conducted such that the welding current and the flow rates of a plasma gas and a shield gas are controlled in accordance with the sizes of said members to be welded and reduced than those in the operation for completely welding said members.
Claim 7
Independent Claim
100 words
A method of conducting a plasma welding which includes the steps of placing members to be welded in abutting relation to each other and conducting a tack-welding of the abutting members for tentatively fixing them together, a keyhole welding of the members to completely weld them together and a finish padding, characterized by: preparing first data concerning the conditions of the individual steps of said tuck welding, keyhole welding and the finish padding; combining said first data with second data concerning the conditions of said members; and automatically conducting the respective welding steps in accordance with the thus combined date.
Claim 8
Independent Claim
100 words
A method of conducting a plasma welding which includes the steps of placing members to be welded in abutting relation to each other and conducting a tack-welding of the abutting members for tentatively fixing them together, a keyhole welding of the members to completely weld them together and a finish padding, characterized by: preparing first data concerning the conditions of the individual steps of said tuck welding, keyhole welding and the finish padding; combining said first data with second data concerning the conditions of said members; and automatically conducting the respective welding steps in accordance with the thus combined date.
Claim 9
Dependent Claim
48 words
A method according to Claim 6, further comprising the steps of: prior to said tack welding, storing third data concerning conditions of a pre-heating operation in relation to the conditions of said members; and pre-heating portions of said members to be welded in accordance with said third data.
Claim 10
Independent Claim
98 words
A method of conducting plasma welding of two members which are placed in abutting relation to each other, characterized by: formulating a time sequence of optimum welding conditions for each of successive operations including a tack welding, a keyhole welding and a finish padding, in relation to the conditions of said members, and inputting the thus formulated time sequence in a controller; and driving a plasma welding torch around said members in accordance with the optimum welding conditions derived from said controller, thereby executing said tack welding, keyhole welding and finish padding under the respective optimum welding conditions.
Claim 11
Independent Claim
98 words
A method of conducting plasma welding of two members which are placed in abutting relation to each other, characterized by: formulating a time sequence of optimum welding conditions for each of successive operations including a tack welding, a keyhole welding and a finish padding, in relation to the conditions of said members, and inputting the thus formulated time sequence in a controller; and driving a plasma welding torch around said members in accordance with the optimum welding conditions derived from said controller, thereby executing said tack welding, keyhole welding and finish padding under the respective optimum welding conditions.
Claim 12
Dependent Claim
142 words
A plasma welding apparatus comprising a welding torch, a gas supply system for supplying a plasma gas to said plasma welding torch, and supporting means for supporting members to be welded, characterized in that said plasma welding torch (7) is rotatably mounted on said supporting means (6), and that said apparatus is provided with a controller (5) adapted for storing a time sequence of optimum welding conditions for successive steps of the welding process in relation to the conditions of said members (15, 16) to be welded, a power supply system (1) for transmitting welding current and welding speed signal to said welding head (6) in accordance with a command provided by said controller (5) and a gas supply system (11, 14a, 18) for supplying a plasma gas (3) at a rate determined in accordance with a command from said controller (5).
Claim 13
Dependent Claim
142 words
A plasma welding apparatus comprising a welding torch, a gas supply system for supplying a plasma gas to said plasma welding torch, and supporting means for supporting members to be welded, characterized in that said plasma welding torch (7) is rotatably mounted on said supporting means (6), and that said apparatus is provided with a controller (5) adapted for storing a time sequence of optimum welding conditions for successive steps of the welding process in relation to the conditions of said members (15, 16) to be welded, a power supply system (1) for transmitting welding current and welding speed signal to said welding head (6) in accordance with a command provided by said controller (5) and a gas supply system (11, 14a, 18) for supplying a plasma gas (3) at a rate determined in accordance with a command from said controller (5).
Claim 14
Dependent Claim
89 words
A plasma welding apparatus according to Claim 9, wherein said welding torch (7) includes an electrode rod (20) adapted to be supplied with said welding current to generate a column of arc (23) between said electrode rod (20) and said members (15,16) to be welded, a torch body (21) surrounding said electrode rod (20) leaving therebetween an annular gap constituting a passage for said plasma gas (3), and a shield cover(22) surrounding said torch body (21) leaving therebetween an annular gap constituting a passage for a shield gas (4).
References Cited (Backward Citations)
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