Electric heating – Metal heating – By arc
Reexamination Certificate
2002-08-16
2004-10-26
Edmondson, L. (Department: 1725)
Electric heating
Metal heating
By arc
C219S074000, C219S121510, C055S482000, C228S019000
Reexamination Certificate
active
06809286
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to welding apparatus, and, more particularly, to a welding apparatus that utilizes a shielding gas during the welding operation.
It is, of course, well known in the use of arc welding apparatus, for the particular arc welding apparatus to utilize a shielding gas, generally an inert gas such as argon, to provide a blanket or shield for the weld as it is being formed. The use of the shielding gas both enhances the performance of the welding apparatus as well as shield the welding area from contaminants. With the use of such shielding gases, it is also common for the gas to be supplied in cylinders that contain the gas at an elevated pressure and that gas is thereafter supplied through gas hoses so that the gas can ultimately be directed onto the weld itself as that weld is being carried out.
Thus, in the system to supply the shielding gas, there normally is a flexible gas hose that is connected to the gas cylinder and which carries the gas to the welding wire feeder. Other standard components include a flow meter located just downstream of the gas valve on the cylinder so that the user can regulate and set the desired flow of the shielding gas to the welding wire feeder. As a further standard component, the shielding gas is turned on and off to the workpiece by means of a gas solenoid valve, generally located at the wire feeder so that the on/off control of the supply of gas can be controlled through an electrical signal.
One problem with the use of such gas solenoid valves, however, is that they are susceptible to damage from dirt or sand dust and the like that, if allowed to invade the internal areas of the gas solenoid valve, can cause harm to the gas solenoid valve and ultimately disrupt its operation. As such, the user then has to disassemble the gas solenoid valve to clean that valve and then reassemble the gas solenoid valve to return the welding apparatus to its operative state. Obviously, such disassembly, cleaning and reassembly causes an undesirable downtime in the operation of the welding apparatus and a reduction of overall efficiency of production for the welding process.
Accordingly, it would be advantageous to be able to avoid the downtime necessitated by the cleaning of the gas solenoid valve and to prevent the dust and unwanted particles from entering into the gas solenoid valve by some means that is easy to use, reliable, relatively inexpensive and which can be added or retrofitted to existing welding apparatus in a quick and efficient manner.
BRIEF DESCRIPTION OF INVENTION
Accordingly, the present invention relates to a gas filter that can be used to prevent particles exceeding a predetermined size from entering into the gas shielding solenoid valve and to a system utilizing that gas filter. With the present invention, a gas filter is located upstream of the gas shielding solenoid valve to filter particles in the stream of the shielding gas from the gas cylinder so that such particles are prevented from entering the gas solenoid valve. By employment of the gas filter, therefore, the harmful particles cannot enter and disrupt the operation of the gas solenoid valve.
With the present invention, the gas filter is comprised of a housing that has an inlet and an outlet with a passageway that extends between the inlet and the outlet. In the preferred embodiment, the housing is a brass housing and the outlet is a male pipe thread fitting that can be connected to the standard female thread fitting of the gas solenoid valve. The inlet of the gas filter is preferably a female pipe thread fitting that can readily be connected to the male fitting of a standard gas hose that normally is used to convey the shielding gas from the gas cylinder to the gas solenoid valve. With the preferred fittings, the present gas filter can readily be added or retrofitted to existing arc welding systems such that the gas filter can be easily and conveniently used to upgrade existing systems.
The gas filter has a filter screen that is retained within the housing and which is preferably constructed of stainless steel with a pore size of about 100 microns so as to prevent any particle exceeding that dimension from passing through the gas filter. The filter screen is located with the passageway such that all of the shielding gas passing through the gas filter must pass through the filter screen, thus effectively filtering all of the shielding gas that can reach the gas solenoid valve.
The passageway is specifically designed to retain the filter screen in place within the housing and to allow the filter screen to be easily inserted into the housing by passing the filter screen through the inlet of the gas filter and progressively moving the filter screen toward the outlet past a portion of the passageway that tapers inwardly, requiring the filter screen to be compressed inwardly and its outer dimension reduced until the filter screen reaches an outwardly extending annular recess formed in the housing. The annular recess has an outer dimension that is about the same as the outer peripheral dimension of the filter screen such that the filter screen can return to its normal dimension and be retained within the annular recess.
At the inner end of the inwardly tapering portion of the passageway, there is therefore formed a sharp circular edge that forms one side of the annular recess and which prevents the filter screen from readily returning outwardly toward the inlet of the gas filter.
Accordingly, with the use of the present gas filter, the housing of the gas filter preferably has an outlet and inlet having the standard threads that are used in the gas system providing the shielding gas to the welding apparatus such that the gas filter can simply be installed by disconnecting the gas hose leading to the gas solenoid valve and by connecting the mating male threads of the gas filter outlet to the female threads of the gas solenoid valve. The male end of the gas hose can then be reattached to the female mating threads of the gas filter to add the protection of the gas filtering capability to a welding system that thereafter protects the gas solenoid valve from the invasion of particles that could damage and disrupt the continuous operation of the welding operation.
These and other features and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein.
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Christopher Mark R.
Piechowski Gerald P.
Edmondson L.
Illinois Tool Works Inc.
Ziolkowski Patent Solutions Group LLC
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