Crc-crose International, Inc.

Other

Crutcher Resources Corporation

Jerome W Nelson

James B Randolph

Robert E Pollock, Deceased

Cherie E Kushner

By Peggy Pollock, Executrix

Ford S Miller

Earl B Nay

Eric W Wittmann

Paul A Tews

To maintain control of arc position in travel along a predetermined welding path, wherein the arc or equivalent heat source is given at least a minimal lateral reciprocation, an electrical characteristic, such as current, is sampled to obtain a continuous signal containing a component which varies with lateral position of the heat source. The first signal is also sampled at the extreme lateral positions of the arc to obtain comparable signal elements which are accumulated, amplified, compared with each other and/or with reference signals, and resultant outputs are used to initiate corrective action. This action may involve giving warning to a human operator or it may involve partial or full control of a physical or mechanical correction procedure. A general application is to the welding of a groove formed between adjacent work pieces. A more specific application is to weld joints involving narrow gaps between length of large pipe in pipeline building. The invention is applicable also to situations wherein lateral oscillation is not really required for gap filling but is used merely as a means to isolate control signals for maintaining an accurate center or main line travel position of the arc of heat source. Moreover, the invention may have a more general application, wherever guidance is desired along a main path that contains any element that effects signal amplitude of a probe characteristic relative to the lateral position of the element where the signal may be masked by noise.

Control of torch position and travel in automatic welding

Signals which contain components that vary with the lateral position of an electric welding instrument as it travels along a weld path between opposite work pieces are obtained from the arc or other heat source and are first processed to remove confusing or nonsignificant components. The processed signals are then compared or combined with each other, or with other signals of predetermined value, to obtain outputs which can be used to determine or control the lateral position or movement of the welding instrument along the weld path. Specifically, in electric arc welding of metals, signals from an electrical characteristic at the arc, such as arc current, which include a component indicative of lateral position of the welding instrument with respect to one or more sidewalls, are first filtered and processed to remove undesirable components. Under control of separate timing signals, the processed signals so obtained are sampled to derive and hold peak values indicative of extreme lateral positions of the instrument as it moves from side to side of its main travel path. By using deliberately timed control signals, these peak values are compared with each other, and/or combined or compared with other signals of known value, to obtain as output the desired position-control signals. The latter are used to indicate, control and/or to change an extreme lateral position of the instrument either by correcting its centerline of main travel and/or by modifying the width or amplitude of its lateral reciprocation.

Method and apparatus for electric arc and analogous welding under

A self-propelled arc welding device, which uses an inert gas within a primary zone to protect superheated metal from contact with atmospheric elements, is shielded with an outer compartment to protect against external air currents in the form of a portable shroud which closes off air currents along the work surface, at least partially. Particularly, for protecting girth welds in pipelines welded by a track-guided machine moving orbitally about the pipe, the compartment includes elements which make a substantially line contact with the pipe surface. The carriage which supports the welding device preferably carries the arc-enclosing shield. An observation window or opening for watching the arc is provided and free access to controls and adjustment means is permitted so that normal control operations are not hampered.

Shielding apparatus

An annular work piece, such as a large pipe, is prepared for welding end-to-end to a similar piece, by a combination of cutting or machining and swaging or cold-rolling, to form bevel, land, and an annular fin-like projection which will better control penetration. In its apparatus aspects, an internal clamp mechanism is used to hold the pipe against rotation while also keeping it essentially circular in outline, a series of cutting tools, preferably complementing each other, is driven around the pipe and end for exterior and interior bevel surfaces with a more or less plane land surface between them. Rollers which serve to constrain and guide the cutting tools are thereafter employed to swage or cold-work the interior of the pipe end to form a small sharp-edged annular projection which serves as a heat sink to control and limit penetration of molten metal from an external electric arc into the interior of the joint. A supplementary back-up or chill may be used for further control, if needed.

Apparatus and method for forming end surfaces on annular work pieces

Apparatus and method for welding girth joints in pipelines and similar structures, of the general type described and claimed in U.S. Pat. No. 3,806,694, is improved by adding to the normal or conventional head, on its frame, a second or supplemental welding head with its own independent wire electrode, electric power and shielding gas supply. The second head is mounted on an adjustable support for accommodating work pieces of different radius or for varying arc positions. Oscillating means for spreading the molten metal across the width of the joint, as normally provided for the single welding head in the patent mentioned, are adapted to operate the second head as well and to vary its amplitude of movement. Separate means are provided for adjusting the spacing between each head and the work and also for lateral adjustment to align the heads with the plane of the joint. By these means, the number of stations required for a multiple pass operation, on thick wall pipe, for example, may be reduced. By operating two welding heads on each of two or more carriages, welding equipment requirements may be cut nearly in half, with beneficial effects on the weld, due to improved thermal effects. Either head may precede the other; cantilever means provide stability for the head mounted most remotely from the frame.

Growing community of inventors

Houston, TX, United States of America

Jerome W Nelson