Abstract: In order to increase the flow rate of coolant liquid supplied to the nozzle (88) of a plasma torch (10) and to extend the life of the plasma torch (10), within the plasma torch (10), an electrode coolant liquid passage (60, 84, 85, 86, and 64) which supplies coolant liquid to an electrode (80), and a nozzle coolant liquid passage (56, 70, 92, 72 and 68) which supplies coolant liquid to the nozzle (88), are provided separately as independent coolant liquid passages which extend in parallel, and which are mutually electrically insulated from one another. Moreover, the flow rate of coolant liquid in the nozzle coolant liquid passage is greater than the flow rate of coolant liquid in the electrode coolant liquid passage.

Abstract: In order to increase the flow rate of coolant liquid supplied to the nozzle (88) of a plasma torch (10) and to extend the life of the plasma torch (10), within the plasma torch (10), an electrode coolant liquid passage (60, 84, 85, 86, and 64 which supplies coolant liquid to an electrode (80), and a nozzle coolant liquid passage (56, 70, 92, 72 and 68) which supplies coolant liquid to the nozzle (88), are provided separately as independent coolant liquid passages which extend in parallel, and which are mutually electrically insulated from one another. Moreover, the flow rate of coolant liquid in the nozzle coolant liquid passage is greater than the flow rate of coolant liquid in the electrode coolant liquid passage.

Abstract: Object of the present invention is to provide uniform heat distribution to a substrate undergoing heat treatment on top of a heat exchange plate. A heat exchange plate 1 is a flat, circular receptacle, has a cooling liquid inflow opening 11 on one end and outflow opening 13 on the other end, and cooling liquid flows on the inside. The surface of the plate 1 is divided, for example, into four zones having different heat capacities and heat transfer characteristics, and an independently controllable foil heater 21A, 23A, 25A, 27A is attached to each zone. Heater 21A covers a zone, which circumferentially surrounds a substrate placed on top of a plate, heater 23A covers a zone directly beneath a substrate, heater 25A covers a zone of the vicinity of the outflow opening 13, and heater 27A covers a zone of the vicinity of the inflow opening 11. Temperature sensors 31-33 are disposed on the inside of a plate at four locations of a second zone, which are apt to receive the affects of the first to fourth zones.

Abstract: A disc heater is applied to a temperature control apparatus which controls a temperature of an object to be processed on at least one surface thereof. In the disc heater, wire-like heating elements are laid on a plate surface in a predetermined pattern and power feeding portions are disposed at ends of the wire-like heating elements. The pattern formed by the wire-like heating elements comprise a large number of arc portions disposed on a large number of concentric circles, and a surface area of the arc portions is 70% or greater, more preferably, 85 to 95% of a surface area of the entire pattern. With this feature, it is possible to effectively reduce the local excessively heated portion to the utmost, and to uniformly heat the entire heating surface, thus realizing an ideal topology pattern of the disc heater.

Abstract: There is provided a plasma arc welding method, characterized in that a portion of a front side workpiece material is heated and melted by a plasma arc to form a molten pool thereat, that the molten pool is held not to fall or drop under a surface tension acting thereto and is brought into contact with a portion of a rear side workpiece material under a pressure which is exerted by the plasma arc and/or a shielding gas, further that the portion of the said rear workpiece material is brought into a molten state by a thermal conduction thereto so that the two workpiece materials may be welded together, and that a swirling flow is imparted to a plasma gas of the plasma arc. There is also provided a plasma welding apparatus for using the above mentioned plasma arc welding method, characterized in that the apparatus comprises: a plasma torch which has a plasma flushing outlet for swirling and flushing a plasma gas of the plasma arc around an electrode therefor.

Abstract: There is provided a plasma arc welding apparatus which comprises a plasma torch and a spacing retention member which is securely fixed to the plasma torch and whose frontal end is located between a frontal end of the plasma torch and a weld workpiece and is adapted to be pressed against the workpiece while the latter is being welded. There is also provided a plasma arc welding method which makes use of a plasma arc welding apparatus that comprises a plasma torch and a spacing retention member which is securely fixed to a base of the plasma torch and whose frontal end is located between a frontal end of the plasma torch and a welding workpiece, in which method the frontal end of the spacing retention member is pressed against the workpiece while the latter is being welded.