Electric heating – Metal heating – By arc
Reexamination Certificate
2000-08-18
2001-12-04
Paschall, Mark (Department: 3742)
Electric heating
Metal heating
By arc
C219S121440, C219S121490, C219S121480, C219S075000, C219S121510
Reexamination Certificate
active
06326581
ABSTRACT:
The invention relates to a blow torch for cutting a workpiece and a method for cutting with the blow torch.
A blow torch for a steam-cutting process is known from JP 02 205 270 A and comprises a control device, a liquid supply system and a power source, the blow torch being connected to the power source by lines. The blow torch is connected to the liquid supply system by a supply line. A flow passage provided in the blow torch is designed so that the liquid is converted into a geas or steam during operation. The flow torch has a cathode and an anode. A line connects the liquid supply system to the intermediate cavity between the cathode and the anode.
EP 0 60 425 B1 discloses a blow torch for a cutting process, in particular a steam-cutting process, in which a container for the liquid, in particular water, is provided in the blow torch. The blow torch has an anode separated from a cathode by an intermediate cavity, an arc being struck between the anode and cathode. In order to ignite the arc, energy is supplied to the blow torch from a power source arranged in a supply unit and pressure is applied by the user in order to push the cathode against the anode so that the arc is ignited when the cathode is moved back from the anode into the non-operating position of the cathode. To enable the fluid to penetrate the intermediate cavity between the anode and the cathode, the container is filled with a porous, heat-conducting material which is joined to a ring sealing off the intermediate cavity so that the fluid, or a gas generated when the fluid is heated, is able to flow from the container into the intermediate cavity through connecting passages in the ring. As a result of the arc ignited in the intermediate cavity, the fluid is transformed from its liquid state into a gaseous state and simultaneously heated, enabling the gas, in particular water vapor, to flow out of the blow torch at high temperature. The disadvantage of this system is that because the container is arranged in the flow torch, the structural dimensions are limited in order to make the blow torch as flexible as possible to manipulate, which means that the container can hold only a small quantity of liquid, making a more lengthy cutting process impossible.
The underlying object of the invention is to provide a blow torch for a cutting process and a method of operating it, capable of achieving a long running time for a cutting process whilst affording the blow torch a high degree of flexibility.
According to one aspect of this invention, this object is accomplished with a blow torch for cutting a workpiece, which comprises a liquid supply system connected to the blow torch by a liquid supply line, a cathode, and an anode, an intermediate cavity being provided between an end of the cathode and the anode. A flow passage surrounds the cathode and has one end arranged to receive liquid from the liquid supply line and an opposite end leading to the intermediate cavity, and a heating element is mounted on the blow torch and controlled to deliver a predetermined amount of heat. The flow passage has a predetermined cross section and is so dimensioned that the predetermined amount of heat completely evaporates the liquid and converts the liquid to a gaseous state in the intermediate cavity.
This offers an advantage due to the fact that no liquid is able to penetrate the intermediate cavity between anode and cathode, which prevents the arc from being extinguished.
A further advantage is that the predetermined path and/or cross section of the duct or flow passage in the blow torch ensures that the liquid is converted into the gaseous state as it leaves the duct or flow passage. Another advantage resides in the fact that by connecting the blow torch to an external liquid supply system, the user is able to run a cutting process without being subjected to a time limit. Yet another advantage is the fact that by arranging the liquid supply system externally, the flow torch can be constructed in a simpler design.
According to another aspect of the invention, there is provided a method of cutting a workpiece with a blow torch comprising a cathode and an anode, which comprises the step of supplying a liquid under pressure to a flow passage surrounding the cathode and having one end arranged to receive the liquid from a liquid supply line and an opposite end leading to an intermediate cavity provided between an end of the cathode and the anode. The liquid flowing through the flow passage is heated, the heating is controlled to deliver a predetermined amount of heat and the quantity of liquid is so controlled that the predetermined amount of heat completely evaporates the liquid and converts the liquid to a gaseous state in the intermediate cavity. An arc is ignited between the anode and cathode.
Various advantageous embodiments are described hereinafter and illustrated in the attached drawings.
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Laimer Johann
Pauser Heribert
Stori Herbert
Collard & Roe P.C.
Fronius Schweissmaschinen Produktion GmbH & Co. KG
Paschall Mark
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