Electric heating – Metal heating – By arc
Reexamination Certificate
2000-08-25
2001-12-04
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C338S153000
Reexamination Certificate
active
06326592
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to electric welding controls, and more particularly to foot controls that regulate welding machine output.
2. Description of the Prior Art
In tungsten inert gas (TIG) welding, it is known to regulate the welding machine output by means of a foot operated remote control. The operator uses his foot to pivot a pedal of the foot control and thereby vary the power at the welding arc.
Because TIG foot controls are typically used on the floor of a workplace, they are subject to hard use and even abuse. For example, the abrasive nature of a concrete floor may subject the foot control to excessive wear.
A related problem is that foot controls are prone to being tipped over. In addition to the potential for being damaged, an overturned foot control requires the operator to bend over and place it upright before it can be used again.
A common characteristic of prior foot controls was that the control cable between them and the welding machines emerged at fixed positions from the foot controls. The fixed position from which the cable emerged from the foot control may have hindered direct routing of the cable between the foot control and the welding machine. Under some operating conditions, the foot control had to be located such that the cable was exposed to workers walking on it or vehicles rolling over it. Additionally, other structures at the work station could interfere with the preferred routing of the cable. Some welding operations required that the foot control be in contact with or very close to a building wall or similar vertical surface. In those situations, it was difficult for the operator to pivot the pedal and obtain desired operation.
An exemplary prior foot control for TIG welding is disclosed in U.S. Pat. No. 5,793,016, the disclosure of which is incorporated by reference herein. The foot control of the U.S. Pat. No. 5,793,016 patent has given satisfactory performance, and it has enjoyed considerable commercial success. Nevertheless, like other prior foot controls, it is subject to further improvements.
SUMMARY OF THE INVENTION
In accordance with the present invention, a foot control for TIG welding machines is provided that is more versatile and stable than prior foot controls. This is accomplished by incorporating multiple control cable outlets in the foot control, and by a stabilizer with a large footprint.
The foot control of the invention may be generally similar to prior foot controls commonly used on TIG welding machines. The foot control has an enclosure with side walls and an open underside that is closeable with a bottom cover. A control cable leads from the enclosure to the welding machine. A pedal pivots on the enclosure. Pivoting the pedal operates components that control the voltage to a TIG welding torch.
According to one aspect of the invention, the enclosure is designed with an opening in more than one of the side walls. In that manner, the cable can be routed to the welding machine that promotes ease of use and protection from damage to the cable. A labyrinth within the enclosure in association with each opening restrains the cable from being pulled out of the enclosure.
The stabilizer is comprised of multiple walls and a top flange. The top flange is inturned from the walls. The stabilizer top flange mounts to the foot control enclosure using the same fastener holes that normally are used for the screws that fasten the bottom cover to the enclosure. Preferably, the stabilizer also has a bottom flange that is outturned from the walls.
To use the stabilizer, the screws fastening the foot control bottom cover to the enclosure are removed, but the bottom cover is not removed from the enclosure. The stabilizer is placed on the bottom cover. Then the screws are replaced to mount the stabilizer to the foot control enclosure. The weight and enlarged footprint of the stabilizer bottom flange add stability to the foot control, as well as providing a larger and harder wear surface.
The features of versatile foot control cable routing and stability are combined by using a base in which the top flange and an adjoining portion of one of the walls are notched to receive the control cable from the foot control enclosure. With the notched base, only one wall of the foot control enclosure need have a control cable opening. In a preferred embodiment, there are four walls in the base. The top flange is slotted in four places, with each of the slots extending into an adjoining portion of a different wall. The slots are sized and shaped to receive a grommet. There is a plate connected to the top flange in operative association with each slot. Each plate has a leg at a distance from the plane of the top flange that is approximately the same as the diameter of the control cable. An arm is also joined to the top flange.
In use, a grommet is slipped over the foot control cable. The screws fastening the foot control bottom cover to the enclosure are removed, but the bottom cover is not removed from the enclosure. The cable is bent downwardly to lie alongside the bottom cover. The cable running end is arranged to pass beyond a selected edge of the bottom cover. The base is placed on the bottom cover, with the notch in the base wall and top flange fitting over the cable standing end, and the selected base slot fitting over the cable grommet. Then the screws are replaced to mount the base to the foot control enclosure. The cable lies between the foot control bottom cover and the plate associated with the selected slot. A strain relief is formed by a screw passing through the base arm, clamping the cable to the bottom cover. In that manner, the control cable can be arranged to emerge from the foot control from any of its sides, even though there is only one cable opening in the foot control enclosure. The plate associated with the base slot that receives the cable supports the cable from drooping below the plane of the bottom flange.
Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.
REFERENCES:
patent: 2308199 (1943-01-01), Mullenbach
patent: 2349891 (1944-05-01), Tyrner
patent: 2379774 (1945-07-01), Wyer
patent: 2383725 (1945-08-01), Landis et al.
patent: 2681586 (1954-06-01), Pressler
patent: 2798209 (1957-07-01), Gordon
patent: 3371506 (1968-03-01), Zahn
patent: 3402341 (1968-09-01), Cook
patent: 4227066 (1980-10-01), Bulwidas
patent: 4322711 (1982-03-01), Spangler et al.
patent: 4345607 (1982-08-01), Contreras
patent: 4787590 (1988-11-01), Melvin
patent: 5793016 (1998-08-01), Colling et al.
patent: 35 44280 A1 (1987-06-01), None
Cayen Donald
Croll Mark W.
Illinois Tool Works Inc.
Pilarski John H.
Shaw Clifford C.
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