Automatic pipe welding system

• US 4,145,593 A
• Filed: 02/03/1976
• Issued: 03/20/1979
• Est. Priority Date: 02/03/1976
• Status: Expired due to Term

• Current Assignee: Crc-Evans Automatic Welding Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Merrick Welding International Incorporated
• Inventors: Cook, George E., Modglin, Donald D., Merrick, George J.
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Shaw, Clifford C.
• Application Number:
  US05/654,975
• Time in Patent Office: 1,141 Days
• Field of Search: 219/60 A, 219/60 R, 219/61, 219/125 R, 219/125 PL, 219/124, 219/131 R, 219/137 R, 219/121 R, 219/135, 219/124.1, 219/125.1, 219/125.11
• US Class Current: 219/60.00A
• CPC Class Codes: B23K 2101/06 Tubes
• CPC Class Codes: B23K 9/0286 with an electrode moving around the fixed tube during the welding operation
• CPC Class Codes: B23K 9/1093 Consumable electrode or filler wire preheat circuits
• CPC Class Codes: B23K 9/323 Combined coupling means, e.g. gas, electricity, water or the like electrical only H01R

Abstract

Apparatus for rapid and automatic welding of joints which interconnect sections of pipe, and in particular oil or gas transmission pipe. The system includes at least one torch transport assembly which simultaneously moves a plural number of welding torches along a path parallel to the pipe joint being welded. The torch transport assembly includes track segments which surround circumferential portions of the pipe joint, with a welding torch carrier and multiple torches being independently movable along each track segment. The torch transport assembly is mounted on a support apparatus which is rigidly clamped to the pipe sections during welding, and which permits the torch transport assembly to be rapidly positioned in rough alignment with a pipe joint. The torch transport assembly and selected operating parameters of each welding torch are adjusted to accurately position each torch with respect to the pipe joint, and to repeatably provide programmed welding parameters resulting in a uniform pipe joint weld. The present system is disclosed in the context of hot-wire gas-tungsten arc welding torches, and in the operating environment of out-of-position joint welding.

Claims

1. Apparatus for welding a circumferential joint about a length of pipe, comprising:

guide means supported by the pipe and defining a fixed path of movement in proximately parallel relation to a circumferential joint to be welded;

carriage means mounted on said guide means and operative for movement along said fixed path;

at least one torch support means carried by said carriage means and supporting a welding torch in welding relation to the pipe joint;

said torch support means being selectably operative independently of said carriage means to vary a selected distance between said welding torch and the circumferential pipe joint;

means responsive to a predetermined welding parameter to provide a parameter responsive signal;

means responsive to the location of said carriage means on said fixed path to provide a carriage location signal corresponding to said carriage location;

command means operative to receive and retain selectably variable parameter command signals that correspond to certain locations of said carriage along said fixed path, and further operative in response to said carriage location signals from said location responsive means to provide said parameter command signals which correspond to the actual location of said carriage;

said torch support means being responsive to said parameter responsive signal and to said parameter command signal to adjust said selected distance so that parameter responsive signal maintains a predetermined relation to said parameter command signal;

said torch support means receiving a welding torch including a filler wire feed appartus with filler wire variable drive means;

means operative to supply a selectably variable amount of heating current to said filler wire at said welding torch;

first control means responsive to said parameter command signal from said command means to adjust said heating current in response to a first predetermined selectably variable function of said carriage location; and

second control means responsive to said parameter command signal from said command means to adjust the rate at which filler wire is supplied by said filler wire drive means in response to a second predetermined selectably variable function of said carriage location.

2. Apparatus as in claim 1, further comprising means responsive to selected heating current and selected feed rate of said filler wire and operative to maintain a selected deposition rate of said filler wire by adjusting said heating current in response to a change in the selected feed rate of said filler wire, and by adjusting said feed rate in response to a change in the selected heating current.

3. Apparatus for welding a circumferential joint about a length of pipe, comprising:

guide means supported by the pipe and defining a fixed path of movement in proximately parallel relation to a circumferential joint to be welded;

carriage means mounted on said guide means and operative for movement along said fixed path;

at least one torch support means carried by said carriage means and supporting a welding torch in welding relation to the pipe joint;

said torch support means being selectably operative independently of said carriage means to vary a selected distance between said welding torch and the circumferential pipe joint;

means responsive to a predetermined welding parameter to provide a parameter responsive signal;

means responsive to the location of said carriage means on said fixed path to provide a carriage location signal corresponding to said carriage location;

command means operative to receive and retain selectably variable parameter command signals that correspond to certain locations of said carriage along said fixed path, and further operative in response to said carriage location signals from said location responsive means to provide said parameter command signals which correspond to the actual location of said carriage;

said torch support means being responsive to said parameter responsive signal and to said parameter command signal to adjust said selected distance so that said parameter responsive signal maintains a predetermined relation to said parameter command signal;

said torch support means receiving a welding torch including a filler wire feed apparatus;

power supply means connected to supply a selectably variable amount of heating current to said filler wire at said welding torch;

means responsive to the location of said carriage means on said fixed path to provide a carriage location signal; and

means operatively associated with said power supply means and responsive to said parameter command signal from said command means to adjust said heating current in response to a predetermined selectably variable function of said carriage location.

4. Apparatus for welding a joint in a workpiece, comprising:

guide means defining a fixed path of movement in proximately parallel relation to the joint to be welded;

carriage means operatively associated with said guide means for selective movement along said fixed path;

a welding torch carried by said carriage means and including filler wire feed means selectably operative to supply filler wire to the weld puddle created by said welding torch;

means operative to supply a selectably variable amount of heating current to said filler wire at said welding torch so as to preheat the filler wire;

first control means responsive to the location of said carriage means along said path to adjust said selected heating current;

second control means responsive to the location of said carriage means along said path to adjust the selected rate at which filler wire is supplied to the weld puddle; and

means responsive to selected heating current and selected feed rate of said filler wire and operatively associated with said first and second control means to maintain a selected deposition rate of filler wire by adjusting said heating current in response to a change in said selected feed rate of filler wire, and by adjusting said feed rate in response to a change in said selected heating current.

5. The process of welding a joint along a path at least part of which is displaced from a horizontal plane, comprising the steps of:

establishing an electric arc with the material being welded so as to create a weld puddle of molten metal at a location on the joint;

moving the arc to traverse the path being welded;

supplying preheated filler metal to said weld puddle while moving said arc; and

controlling the preheating of said filler metal in response to a selectably variable function of the location along said path, so that the size of said weld puddle does not exceed a size whereat natural forces acting on said puddle retain the puddle in the joint in opposition to gravitational attraction tending to pull the puddle out of said joint at nonhorizontal locations along said path.

6. The process of welding a jont along a path at least part of which is displaced from a horizontal plane, comprising the steps of:

establishing an electric arc with the material being welded so as to create a weld puddle of molten metal at a location on the joint;

moving the arc to traverse the path being welded;

supplying preheated filler metal to said weld puddle while moving said arc; and

controlling the preheating of said filler metal and the rate at which said preheated filler metal is supplied to said weld puddle, in response to a selectably variable function of the location along said path, so that the size of said weld puddle does not exceed a size whereat natural forces acting on said puddle retain the puddle in the joint in opposition to gravitational attraction tending to pull the puddle out of said joint at nonhorizontal locations along said path.

7. The process of claim 6, wherein said welding occurs about a circumferential joint of a pipe, and said arc is moved in a circular path proximately concentric with said joint.

8. The process of welding as in claim 6, wherein said electric arc that is established and moved to traverse the region being welded is a nonpulsed electric arc.