Electric heating – Metal heating – By arc
Reexamination Certificate
2000-09-21
2001-06-26
Paschall, Mark (Department: 3742)
Electric heating
Metal heating
By arc
C219S121480, C219S075000
Reexamination Certificate
active
06252194
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an assembly of an electrode body/electrode carrier for a plasma torch, to a plasma torch provided with such an assembly, and to a process for welding, cutting or marking with the plasma arc, adapted to use such a torch.
BACKGROUND OF THE INVENTION
Conventionally, plasma torches are comprised by a torch body with, in its rear portion, connections to fluid supply conduits, particularly of plasmagenic gas, an electric current, and in its front portion, means for mounting the electrode body and the nozzle.
In certain cases, so as particularly to facilitate maintenance and/or replacement of the worn or defective pieces, the torch can be provided with quick assembly/disassembly means, as described in the document EP-A-599709, which is incorporated herein by reference.
As set forth in detail hereafter, in conventional plasma torches, the electrode properly so called is generally carried by a support element, also called an electrode body, which performs moreover a radiator function by permitting the discharge of a portion of the heat given off during welding, cutting or plasma marking, by heat exchange with a cooling fluid.
Conventionally, the electrode body has the shape of a tapped sleeve of circular cross-section. The tapping provided on a portion of the internal peripheral surface of the sleeve permits ensuring securement by screwing of the electrode body onto the electrode carrier, which has a complementary screw thread on it external circumference.
However, it has been observed that with this type of mounting relying solely on securement by screwing, the centering of the electrode body is not always correctly ensured.
There accordingly results accelerated deterioration, particularly of the electrode properly so called and in particular of the nozzle, thereby giving rise to more frequent replacement of the assembly constituted by the electrode and the torch nozzle and correspondingly an increase of cost.
Moreover, if an increase in the length of the screw threading permits partially overcoming this problem of bad centering of the electrode, this solution cannot be considered as totally satisfactory because it involves a decrease of the internal surface permitting heat exchange between the cooling fluid and the electrode body and hence an important loss of cooling efficiency of this latter. In other words, the increase of the length of the securement screw threads takes place to the detriment of heat exchange, which is not acceptable.
OBJECT OF THE INVENTION
The object of the present invention is therefore to overcome the mentioned problems by providing a male/female assembly for a plasma torch whose structure permits in particular improving the centering of the electrode body along the electrode carrier and this without requiring an increase of the length of the securement screw threads.
SUMMARY OF THE INVENTION
The present invention thus relates to a male/female assembly for a plasma torch comprising an electrode body having substantially the shape of a sleeve forming the female portion and an electrode carrier having a substantially elongated shape forming the male portion, in which:
the electrode body comprises, on an upstream portion of its internal periphery, at least one tapping in which is provided at least one recess extending over all the length of the tapping, the tapped portion having, in transverse cross-section, a diameter D
1
, and at least one downstream portion defining a recess of diameter D
2
located between the upstream tapped portion and the bottom of the electrode body, with D
2
> D
1
, and
the electrode carrier comprises, on its external peripheral surface, at least one gauge having at least locally a transverse cross-sectional profile corresponding to the profile of said at least one recess of the electrode body and at least one screw thread, said gauge being located between the downstream end of the electrode carrier and said screw threading.
As the case may be, the male/female assembly according to the invention can comprise one or several of the following characteristics:
the electrode body comprises several recesses;
the recesses of said electrode body form, in transverse cross-section, a polygon;
the recesses form a polygon selected from triangle, square, pentagon, hexagon, heptagon and octagon;
the bottom of the electrode body, which is to say its active end, comprises moreover an electrode.
The invention also relates to an electrode body adapted to constitute the female portion of a male/female assembly according to the invention and an electrode carrier adapted to constitute the male portion of a male/female assembly according to the invention.
According to still another aspect, the invention relates to a plasma torch of an automatic machine or any similar mechanized device, comprising an electrode body and/or an electrode carrier, as mentioned above.
The invention moreover relates to a process for cutting, welding or marking with an arc plasma adapted to use a plasma torch according to the invention.
REFERENCES:
patent: 4059743 (1977-11-01), Esibian
patent: 4250373 (1981-02-01), Tanida
patent: 5097111 (1992-03-01), Severance, Jr. et al.
patent: 5938949 (1999-08-01), Enyedy et al.
patent: WO 98/19504 (1998-05-01), None
La Soudure Autogene Francaise
Paschall Mark
Young & Thompson
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