Method for metallurgically joining a tube to a member

A method for metallurgically joining a tube to a member comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes a fold, and wherein the fold includes longitudinally-spaced-apart first and second fold portions;
• b) obtaining a member;
• c) after steps a) and b), disposing the tube and the member with the end portion contacting the member;
• and
• d) after step c), creating a resistance welding current path through the tube and the member proximate the end portion and relatively longitudinally moving the end portion deformingly against the member creating a weld zone which includes at least some of the end portion and at least some of the member, wherein the fold is an annular fold substantially coaxially aligned with the longitudinal axis, wherein step d) creates an annular weld zone, and wherein the end portion includes at least one additional annular fold coaxially aligned with the longitudinal axis and having two longitudinally spaced-apart fold portions.

A method for metallurgically joining a tube to a member comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes a fold, and wherein the fold includes longitudinally-spaced-apart first and second fold portions;
• b) obtaining a member;
• c) after steps a) and b), disposing the tube and the member with the end portion contacting the member;
• and
• d) after step c), creating a resistance welding current path through the tube and the member proximate the end portion and relatively longitudinally moving the end portion deformingly against the member creating a weld zone which includes at least some of the end portion and at least some of the member, wherein the fold is an annular fold substantially coaxially aligned with the longitudinal axis, wherein step d) creates an annular weld zone, and wherein the annular fold is a radially-inwardly-protruding annular fold.

A method for metallurgically joining a tube to a member comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes a fold, and wherein the fold includes longitudinally-spaced-apart first and second fold portions;
• b) obtaining a member;
• c) after steps a) and b), disposing the tube and the member with the end portion contacting the member;
• and
• d) after step c), creating a resistance welding current path through the tube and the member proximate the end portion and relatively longitudinally moving the end portion deformingly against the member creating a weld zone which includes at least some of the end portion and at least some of the member, wherein the fold is an annular fold substantially coaxially aligned with the longitudinal axis, wherein step d) creates an annular weld zone, and wherein step d) does not melt any of the end portion and does not melt any of the member.

A method for metallurgically joining one tube to another tube comprising the steps of:

• a) obtaining a first tube having a longitudinal axis and having a first end portion, wherein the first end portion includes a first annular fold substantially coaxially aligned with the longitudinal axis, wherein the first annular fold includes an inner surface, and wherein substantially no portion of the inner surface of the first annular fold is in folded contact with any other portion of the inner surface of the first annular fold;
• b) obtaining a second tube having a second end portion;
• c) after steps a) and b), coaxially aligning the first and second tubes and disposing the first and second tubes with the first end portion contacting the second end portion;
• and
• d) after step c), creating a resistance welding current path through the first and second tubes proximate the first and second end portions and relatively longitudinally moving the first end portion deformingly against the second end portion creating an annular weld zone which includes at least some of the first end portion and at least some of the second end portion.

A method for metallurgically joining one tube to another tube comprising the steps of:

• a) obtaining a first tube having a longitudinal axis and having a first end portion, wherein the first end portion includes a first annular fold substantially coaxially aligned with the longitudinal axis, and wherein the first annular fold includes longitudinally-spaced-apart first and second fold portions;
• b) obtaining a second tube having a second end portion;
• c) after steps a) and b), coaxially aligning the first and second tubes and disposing the first and second tubes with the first end portion contacting the second end portion;
• and
• d) after step c), creating a resistance welding current path through the first and second tubes proximate the first and second end portions and relatively longitudinally moving the first end portion deformingly against the second end portion creating an annular weld zone which includes at least some of the first end portion and at least some of the second end portion, wherein the second end portion includes a second annular fold having longitudinally spaced-apart third and fourth fold portions, wherein the wall thicknesses of the first and second tubes are substantially equal, and wherein step c) disposes the first and second tubes with the second annular fold longitudinally contacting the first annular fold.

A method for metallurgically joining a tube to a plate comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes an annular fold substantially coaxially aligned with the longitudinal axis, and wherein the annular fold include an inner surface, and wherein substantially no portion of the inner surface of the fold is in folded contact with any other portion of the inner surface of the fold;
• b) obtaining a plate having first and second sides;
• c) after steps a) and b), aligning the tube substantially perpendicular to the plate and disposing the tube and the plate with the end portion contacting the second side;
• and
• d) after step c), creating a resistance welding current path through the tube and the plate proximate the end portion and relatively longitudinally moving the end portion deformingly against the plate creating an annular weld zone which includes at least some of the end portion and at least some of the plate.

A method for metallurgically joining a tube to a member comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes a fold, and wherein the fold includes an inner surface having opposing, substantially parallel, and longitudinally-spaced-apart first and second surface portions;
• b) obtaining a member;
• c) after steps a) and b), disposing the tube and the member with the end portion contacting the member;
• and
• d) after step c), creating a resistance welding current path through the tube and the member proximate the end portion and relatively longitudinally moving the end portion deformingly against the member creating a weld zone which includes at least some of the end portion and at least some of the member.

A method for metallurgically joining a tube to a member comprising the steps of:

• a) obtaining a tube having a longitudinal axis and having an end portion, wherein the end portion includes a fold, and wherein the fold includes an inner surface having opposing first and second surface portions which are longitudinally spaced apart and which have a radial extent greater than the wall thickness of the tube;
• b) obtaining a member;
• c) after steps a) and b), disposing the tube and the member with the end portion contacting the member;
• and
• d) after step c), creating a resistance welding current path through the tube and the member proximate the end portion and relatively longitudinally moving the end portion deformingly against the member creating a weld zone which includes at least some of the end portion and at least some of the member.