Electric heating – Metal heating – Of cylinders
Reexamination Certificate
2000-12-04
2002-06-18
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
Of cylinders
C219S125110
Reexamination Certificate
active
06407355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to orbital welders, and more particularly to a novel orbital welder facilitating easier tube alignment and capable of forming non-planar welds.
2. Description of the Background Art
Orbital welders are widely used in the construction of fluid handling systems, for example semiconductor processing equipment. Known orbital welders join metal tubes in an end-to-end fashion by forming a flat, circular weld around the circumference of the tube's open end. One problem encountered by conventional orbital welders is that the ends of the tubes which are to be joined must be carefully aligned prior to performing the welding operation. Additionally, because known orbital welders are limited to forming flat, circular welds (i.e., a circular weld lying in a single plane), special tube preparation is required to weld a cross or a tee (“T”) joint.
FIG. 1
is a top plan view of a typical orbital welder
100
, which includes an insulating housing
102
, tube clamps
104
and
106
, a rotor
108
, a weld tip
110
, and a rotation and voltage controller
112
. Clamps
104
and
106
hold tubes
114
and
116
, respectively, in position for welding, and are maintained at a common voltage (e.g., ground) and in electrical contact with tubes
114
and
116
. Rotor
108
is disposed within housing
102
so as to be rotatable about an axis
118
passing through the center of the open ends of tubes
114
and
116
. Housing
102
provides electrical insulation between rotor
108
and clamps
104
and
106
. Rotation and voltage controller
112
functions to rotate rotor
108
within housing
102
, and to apply a voltage, via rotor
108
, to attached weld tip
110
.
FIG. 2
shows a cross-sectional view of orbital welder
100
. As controller
112
rotates rotor
108
about axis
118
and applies a high voltage to weld tip
110
, an arc weld
202
is formed between the open ends of tubes
114
and
116
. Because clamps
104
and
106
are held at the common voltage, they must be displaced a safe distance from weld tip
110
, so as not to generate an arc therebetween. The distance between clamps
104
and
106
and the open ends of tubes
114
and
116
makes alignment of the open ends of tubes
114
and
116
more difficult. Moreover, the interior chambers of known orbital welders are dark, and, therefore, visual confirmation of proper alignment is difficult.
FIG. 3
is a cross-sectional view of an orbital welder
300
capable of forming a flat “T” weld. Orbital welder
300
includes an insulating housing
302
, a tube clamp
304
, a “T” fitting clamp
306
, a rotor
308
, a weld tip
310
, and a rotation and voltage controller
312
.
Orbital welder
300
functions similarly to orbital welder
100
. Clamps
304
and
306
hold a tube
314
and a T-fitting
316
in position and at a common voltage. Rotation and voltage controller
312
causes rotor
312
to rotate about an axis
318
, and applies a high voltage, via rotor
308
, to weld tip
310
. As rotor
308
rotates about axis
318
, a weld
320
is formed between the open ends of tube
314
and T-fitting
316
.
FIG. 4
is a perspective view of T-fitting
316
. In order to make T-fitting
316
from a standard piece of tube stock
402
, an opening
404
is first cut or ground into the tube stock
402
. Next, an extrusion process is required to draw the tube material surrounding opening
404
into an extended portion
406
defining a flat circular opening
408
. Because the extrusion process is relatively complex, workers cannot weld T-joints quickly and easily on job sites, from standard tube stock. Additionally, for commonly used 0.25 in. O.D. tubing, the extrusion process is generally limited to tubes with a wall thickness of 0.028 in. or less, and is therefore unavailable for the preferred 0.035 in. walled tubing.
What is needed is an orbital welder capable of welding T-joints and cross-joints from standard tube stock. What is also needed is an orbital welder which facilitates easy alignment of the tube pieces which are to be welded. What is also needed is an orbital welder with that facilitates easy visual confirmation of proper alignment.
SUMMARY
A novel orbital welder capable of forming non-planar orbital welds is described. The use of non-planar orbital welds facilitates the construction of various tube joints, including T-joints, cross-joints, and end-to-end joints, form standard tube stock by workers in the field.
One embodiment includes a weld tip, a rotational controller, and a translational controller. The rotational controller causes the weld tip to rotate about an axis passing through the tube to be welded. As the weld tip rotates about the axis, the translational controller causes the weld tip to move longitudinally with respect to the axis. Thus, non-planar orbital welds can be formed.
In a particular embodiment, the translational controller includes a rotor which is slidably disposed in an insulating body, and the weld tip is fixed directly to the rotor. As the rotor rotates about the axis, the translational controller causes the rotor to move longitudinally with respect to the axis of rotation, such that the weld tip follows a non-planar weld pattern.
In another particular embodiment, the rotational controller includes a rotor disposed to rotate about the axis, but remains within the plane of rotation. The translational controller includes a carrier that is slidably attached to the rotor, and the weld tip is fixed to the carrier. As the rotor rotates about the axis, the carrier moves longitudinally with respect to the axis, such that the weld tip follows a non-planar weld pattern. In a more particular embodiment, a portion of the carrier is biased against a surface of a cam block, and optionally includes a wheel for reducing the friction between the carrier and the cam block. The surface of the cam block is contoured to displace the carrier longitudinally with respect to the axis of rotation as the rotor rotates about the axis. Alternatively, the surface of the cam block is flat, and the cam block is displaced longitudinally as the rotor rotates about the axis of rotation.
In an alternate embodiment, the translational controller includes a wall with a groove that defines the desired weld pattern. A guide pin extends from the carrier into the groove. As the rotor rotates about the axis of rotation, the pin follows the groove, moving the carrier longitudinally with respect to the axis of rotation.
Another embodiment, particularly suited for welding cross-joints includes two weld tips, two rotational controllers, and two translational controllers. In a particular embodiment, each translational controller includes a rotor which rotates about an axis of rotation, and which moves longitudinally with respect to the axis. Each weld tip is fixed to one of the rotors, and, therefore, moves along a non-planar circular path. In an alternate embodiment, each translational controller includes a rotor which rotates about an axis, but which is fixed in the plane of rotation. Each weld tip is fixed to a separate carrier which is slidably attached to a respective one of the rotors. Each of the carriers is biased against an associated one of two cam blocks. As the rotors rotate about the axes of rotation, the cam blocks displace the carriers longitudinally. The attached weld tips follow non-planar orbital weld patterns. Optionally, a single rotational controller controls both rotors
Any of the described embodiments may include an optional light source for illuminating the interior chamber of the orbital welder. In one embodiment, the body of the orbital welder includes a light conducting portion for transmitting light from the light source to the interior chamber. In a more particular embodiment, the light conducting portion is formed as a layer of the body of the orbital welder, and the light source is disposed in an opening in, or along the edge of, the light conducting layer. Optionally, the light source is disposed within the interior chamber of the welder. Typ
Henneman & Saunders
Henneman, Jr. Larry E.
Shaw Clifford C.
Therma Corporation, Inc.
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