Method of forming, inserting and permanently bonding ribs in boiler tubes
View Patent ↗A method of providing boiler tubes with a variably ribbed interior surface. A suitably dimensioned spindle with a channel having a desired pattern on the exterior surface of the spindle is wrapped by a wire-like member in the channel so as to form thereon a reverse image of the desired, patterned tube ribbing. A brazing metal paste is applied on the exterior surface of the wire-like member and the spindle is inserted into a tube to be ribbed. The wire-like member is released from the spindle to allow the wire-like member to conform to the inner surface of the tube, and the tube is heated to the melting temperature of the brazing metal paste so that the wire-like member bonds to the inner surface of the tube, and the metal tube is then cooled.
1. A method for forming a ribbing in an inner wall of a tubular member comprising the steps of:
providing a spindle having a lesser diameter than the internal diameter of the tubular member;
compressively wrapping a wire-like member helically along the length of the spindle;
applying a metal brazing material onto an exterior surface of the wire-like member;
inserting the spindle with the wire-like member wrapped thereon into the interior of the tubular member;
releasing the compression on the compressively wrapped wire-like member;
withdrawing the spindle from the tubular member thereby leaving the wire-like member in the tubular member such that the wire-like member remains in the tubular member;
heating the tubular member thereby melting the metal material to bond the wire-like member to an inner surface of the tubular member;
wherein the metal material is BNi-2 nickel-bearing brazing filler paste;
wherein the wire-like member has a quadrilateral cross section.
2. The method as claimed in claim 1 wherein the spindle comprises a helical shaped channel.
3. The method as claimed in claim 1 further including the step of attaching an end of the wire-like member to the spindle to prevent the end of the wire-like member from becoming dislodged from the spindle.
4. The method as claimed in claim 1 wherein the wire-like member has a circular cross section.
5. The method as claimed in claim 1 wherein the wire-like member has a trapezoidal cross section.
6. The method as claimed in claim 1 wherein the wire-like member has a trapezoidal cross section.
7. A method for forming a helical ribbing in the inner wall of a tubular member comprising the steps of:
providing a spindle having a lesser diameter than the internal diameter of the tubular member, the spindle having a helical channel extending a length of the spindle;
wrapping a wire-like member in the helical channel of the spindle;
attaching an end of the wire-like member to the spindle to prevent the end of the wire-like member from becoming dislodged from the spindle;
applying BNi-2 nickel-bearing brazing paste onto an exterior surface of the wire-like member;
inserting the spindle with the wire-like member wrapped thereon into the interior of the tubular member;
releasing the compression on the compressively wrapped wire-like member;
withdrawing the spindle from the tubular member thereby leaving the wire-like member in the tubular member such that the wire-like member expands to conform to an inner surface of the tubular member; and
heating the tubular member at a temperature which is at least the melting point of the BNi-2 nickel-bearing brazing filler thereby melting the BNi-2 nickel-bearing brazing filler to bond the wire-like member to an inner surface of the tubular member.
8. A method for forming a ribbing in an inner wall of a tubular member comprising the steps of:
providing a spindle having a lesser diameter than the internal diameter of the tubular member;
compressively wrapping a wire-like member helically along the length of the spindle;
applying a metal brazing material to the interior surface of the tubular member;
inserting the spindle with the wire-like member wrapped thereon into the interior of the tubular member;
releasing the compression on the compressively wrapped wire-like member;
withdrawing the spindle from the tubular member thereby leaving the wire-like member in the tubular member such that the wire-like member remains in the tubular member; and
heating the tubular member thereby melting the metal material to bond the wire-like member to an inner surface of the tubular member.
9. The method as claimed in claim 8 wherein the spindle comprises a helical shaped channel.
10. The method as claimed in claim 8 wherein the metal material is BNi-2 nickel-bearing brazing filler paste.
11. The method as claimed in claim 8 further including the step of attaching an end of the wire-like member to the spindle to prevent the end of the wire-like member from becoming dislodged from the spindle.
12. The method as claimed in claim 8 wherein the wire-like member has a circular cross section.
13. The method as claimed in claim 8 wherein the wire-like member has a rectangular cross section.
14. The method as claimed in claim 8 wherein the wire-like member has a trapezoidal cross section.