Electric heating – Metal heating – Nonatmospheric environment at hot spot
Reexamination Certificate
1999-08-20
2001-02-20
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
Nonatmospheric environment at hot spot
C219S136000
Reexamination Certificate
active
06191378
ABSTRACT:
The invention relates to a welding apparatus, that includes a welding machine, that has at least a supply unit for welding current and means for adjustment of the welding current, shielding gas unit, that has at least means for observing, adjusting and/or for the like processing of the feed volume of the shielding gas, and a nozzle part, that is to be kept in hand and that is connected to the welding machine preferably by means of a flexible pipe unit. The welding rod, that is led to the welding point from the shielding gas unit, is arranged to be melted while being protected by the shielding gas in connection with the nozzle part by means of an arc achieved by influence of the supply unit for welding current. To improve fire safety of the welding occasion, such as to eliminate risk of fire or to suppress fire, the welding apparatus includes furthermore a coupling arrangement to lead shielding gas, that is led from the shielding gas unit belonging to the welding machine during a protecting occasion to the point, that is exposed for risk of fire or that is already burning, which coupling arrangement includes organs, that are arranged to interrupt at least supply of welding current to the nozzle part and to lead shielding gas to the point exposed for fire or that is burning, preferably by means of the flexible pipe unit through the nozzle part of an essentially increased volume flow rate in respect to the welding occasion.
The type of welding method described above corresponds to e.g. so called TIG-welding, that is being exploited very commonly for e.g. welding of thin sheet metal in such as e.g. garages or like. The method may be utilized as well in connection with so called MIG-welding, whereby the welding machine includes further more at least a unit for rod supply and means for regulating of the feed velocity of the rod. In this case also feeding of the welding rod from the rod supply unit through the nozzle part to the welding point is carried out by means of the flexible pipe unit.
A Finnish patent application FI 945614 and an application document DE 3 404 614 disclose the type of solutions above, that are intended for improvement of fire safety of the welding occasion. From the above it is known, that shielding gas, that is led from a shielding gas unit belonging to a so called MIG-welding apparatus, is being led to the point exposed for fire or that is burning through the nozzle part by means of organs, that are operated by means of a switch being placed advantageously in connection with the nozzle part, that during a trouble occasion interrupts supply of welding current and welding rod as well as switch on the feed volume of the shielding gas to be led by the nozzle part at an essentially increased rate in respect to the welding occasion.
Neither solution of the above discloses simple enough solutions particularly with a view to technical realization and due to the above with a view to manufacturing costs either, but in both of the above solutions internal couplings in respect to the welding machine are always requested to carry out flow techniques. This naturally requires in most cases cooperation with welding machine manufacturers, which particularly tends to rise manufacturing costs of welding apparatuses. In addition to the above it is very difficult in this type of solutions to amend in some other way already present welding apparatuses safer in the purpose described above.
It is an aim of the welding apparatus according to this invention to achieve a decissive improvement in the problems presented above and thus to raise essentially the level of the present: prior art in the field. To bring out this aim the welding apparatus according to the invention is mainly characterized by, that a flow arrangement belonging to the coupling arrangement is arranged essentially externally in respect to the welding machine at least with a view to flow techniques, by leading shielding gas during the protecting occasion in question directly from the shielding gas unit past the welding machine to the nozzle part.
As the most important advantages of the welding apparatus according to the invention may be mentioned simplicity and reliability of installation and use of the same, whereby by aid of the same it is possible with very simple arrangements and that is why also with profitable costs as well to secure a good safety of work of the work environment particularly with a view to fire safety e.g. by complementing usual welding machines by coupling arrangements according to the invention. The exploitation of the welding apparatus according to the invention is thus extremely simple, whereby prevention of a fire occasion is carried out as an advantageous embodiment very quickly by using only a switch in the nozzle part, in which case the organs being connected to the same e.g. during a MIG-welding interrupt feeding of welding current and of the rod to the nozzle part and in the same context switch on the shielding gas flow to the nozzle part, the volume rate of which is increased in respect to the same during a welding occasion. The welding apparatus according to the invention improves thus significantly safety of work, whereby fire damages caused directly or undirectly by welding may in the first place be controlled with profitable costs with a view to investment costs as well as prevented with simple and efficient enough arrangements from the point of view of the welder.
The dependent claims directed to the welding apparatus present advantageous embodiments of the welding apparatus according to the invention.
In the following description the invention is being explained in more detail with reference to the enclosed drawings, in which
FIG. 1
shows an advantageous embodiment of the invention in connection with a so called TIG-welding apparatus,
FIG. 2
shows furthermore an advantageous embodiment of the invention in connection with a so called MIG-welding apparatus, and
FIG. 3
shows an advantageous embodiment according to the invention in connection with a so called pressure reduction arrangement.
REFERENCES:
patent: 3945440 (1976-03-01), Bohme
patent: 4093191 (1978-06-01), Ferguson
patent: 4634833 (1987-01-01), Chemnitz
patent: 4760994 (1988-08-01), Ferguson
patent: 3404314 (1984-08-01), None
patent: 98438 (1997-03-01), None
patent: 1220828 (1971-01-01), None
Asko Taipale Oy
Pollock, Vande Sande & Amernick RLLP
Shaw Clifford C.
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