Method for forming a brazed joint

Abstract

The disclosed apparatus, systems and methods relate to the design principles for forming a welded joint between two sections of tubing or pipe. The material at the end portion of a first section of tubing to is folded inwardly to create a support surface. This support surface improves the ability to weld light gage material with traditional arc welding and it creates conditions to allow brazing to be as strong as traditional arc welding by using A shaped piece of filler material which is located at the intersection between the support surface of the first section of tubing and a side wall section of the second section of tubing. While holding together the first and second sections of tubing with the filler material, heat is applied at the intersection at a temperature and for a duration sufficient to melt the filler material and form the 3t joint.

Claims

1. A method for forming a joint, comprising: joining a first elongate tube to a second elongate tube to form an intersection including a filler material, wherein the first elongate tube comprises: (a) a lumen; and (b) a support section flange extending into the lumen, and wherein the second elongate tube comprises a side wall section; applying heat to the intersection; and brazing and forming a joint satisfying the 3T rule.

2. The method of forming a joint of claim 1, wherein the support section flange is round.

3. The method of forming a joint of claim 1, wherein the support section flange is square.

4. The method of forming a joint of claim 1, wherein the filler material is selected from the group consisting of silicon-bronze, aluminum-silicon, copper, brass and bronze.

5. The method of forming a joint of claim 1, wherein the joint is constructed and arranged so as to have at least three times the surface contact as the thinnest portion of the first or second elongate tube.

6. The method of forming a joint of claim 5, wherein a surface contact area of the support section flange is at least five times greater than a thickness of the first elongate tube.

7. The method of forming a joint of claim 1, wherein the support section flange creates a heat sink during brazing.

8. A method for forming a brazed joint comprising: folding inward at least one end of a first elongate tube to form a flange; aligning the first elongate tube with a second elongate tube to form an intersection; placing a filler material between the flange and a second elongate tube; applying heat to the intersection; and melting the filler material to form a joint between the first elongate tube and the second elongate tube via brazing, wherein the flange has a contact area at least three times greater than a thickness of the first elongate tube.

9. The method of claim 8, wherein the contact area at least five times greater than a thickness of the first elongate tube.

10. The method of claim 8, wherein the flange forms a saddle.

11. The method of claim 10, wherein the joint at least meets the 3T rule.

12. The method of claim 10, wherein the filler material has a melting point lower than a melting point of the first and second elongate tubes.

13. The method of claim 12, wherein the filler material is at least one of silicon bronze, aluminum-silicon, copper, brass, and bronze.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view of a piece of tubing or pipe in which a coped end condition of the jointing system has been formed in one end of the tubing, according to one implementation.

(2) FIG. 2 is a perspective view of the embodiment of FIG. 1.

(3) FIG. 3 is an end view of the coped end condition of the embodiment of FIG. 1.

(4) FIG. 4 is a side view of the piece of tubing of FIG. 1 welded to a perpendicular piece of tubing or pipe material.

(5) FIG. 5 is a perspective view corresponding to FIG. 4.

(6) FIG. 6 is a perspective view of a piece of filler material used in forming the welded coped joint of the jointing system as shown in FIGS. 4 and 5.

(7) FIG. 7 is a side view of a piece of tubing or pipe of an alternative embodiment of the jointing system wherein a straight end condition has been formed in the end of the tubing or pipe, according to one implementation.

(8) FIG. 8 is a perspective view of the tubing or pipe of FIG. 7.

(9) FIG. 9 is an end view of the tubing or pipe of FIG. 7.

(10) FIG. 10 is a perspective view of a piece of filler material used in forming a welded joint of the jointing system, according to one implementation.

(11) FIG. 11 is a side view of a T-joint formed between the piece of tubing or pipe of FIG. 7 and a perpendicular piece of flattened tubing or pipe material.

(12) FIG. 12 is a perspective view corresponding to FIG. 11, according to one implementation.

(13) FIG. 13 is partially transparent detail view corresponding to FIG. 12 and showing the welded joint, according to one implementation.

(14) FIG. 14 is an enlarged cross-sectional view of welded joint formed between the straight end condition tubing or pipe of FIGS. 7-9 and a perpendicular piece of tubing or pipe, according to one implementation.

(15) FIG. 15 is a perspective view of a tube or pipe having an opening set in the body, according to one implementation.

(16) FIG. 16 is a further perspective view of a tube or pipe having an opening set in the body, according to one implementation.

DETAILED DESCRIPTION

(17) The various embodiments disclosed or contemplated herein relate to devices, systems and methods for forming a joint, which are collectively referred to herein as the “joint system.” In various implementations of the joint system, a state, opening or “condition” is formed in a piece of tubing or pipe that greatly increases the surface area to be joined to a second section of tubing or pipe. The increased surface area of the condition simplifies the welding process and creates a much stronger joint.

(18) Turning to the drawings in greater detail, FIGS. 1-3 depict implementations of the system 1 having a pipe 10, such as a tube or other known elongate metal portion known in the welding arts. In these implementations, the pipe 10 has a round cross section and first 10A and second 10B ends. As discussed below, many alternate implementations are possible. It will be appreciated that the disclosed implementations of the jointing system are particularly suited for joining light gage tubing or pipe 10, and these implementations enable even a relatively unskilled welder to quickly create strong, reliable joints without error.

(19) In the implementations of FIGS. 1-3, a saddle or coped end condition 12 has been formed in one end 10A section of the tubing 10. It is understood that in various implementations, this condition 12 can be formed at either, or both 10A, 10B ends. In various implementations, the condition 12 can be formed by the skilled artisan by “folding” portions of the tube (shown generally at 14) inward to form a flange or support section 14. It is understood that this support section 14 provides greater surface area for coupling the tube 10 to another metal portion, such as a rounded tube, to form a joint, as is shown in FIGS. 4-5. In one non-limiting example, if the tubing 10 is 18 gage, 1.66 inch OD tubing, the surface area at the union is increased by five times, from 0.228 sq. in. to 1.156 sq. in. It is understood that myriad additional sizing options and implementations are possible.

(20) Accordingly, it is understood that in these implementations, the support section 14 material (such as at end 10A of the tubing 10 or pipe, or within the length of the tube, as described below) is folded inward, creating a flange section 14 having a large surface area. Folding in of the material of the support section 14 rather than removing it also eliminates the sharp edge which reduces the risk of blowing a hole during the welding process. Instead, in these implementations, a rounded surface is created at the location of the fold. Further, the in-folded material of the support section 14 creates a support for the joining process, according to these implementations.

(21) In addition, the folded material of the support section 14, according to the implementations of FIGS. 1-3 and below presents additional mass at the site of the joint (shown, for example in FIG. 4 at 20) that provides support for the weld puddle being created at the weld seam, as would be appreciated by one of skill in the art.

(22) Accordingly, as shown in the implementations of FIGS. 4-5, in use it is possible to form a perpendicular joint with a second section of tubing or pipe 16 (FIGS. 4 and 5). In these implementations, as best shown in FIG. 6, a substantially planar filler material 18 is cut and shaped into a disc- or other shaped “sheet” 18 to correspond generally to the coped end condition 12.

(23) In use, heat is then applied at the joint at a temperature and duration sufficient to melt the filler material 18 which is used for brazing to form the brazed union 20. In one implementation, filler material 18 is silicon bronze. It is understood that many other materials can be used for the filler material 18, some non-limiting examples including aluminum-silicon, copper, brass, bronze and the like. One of skill in the art would appreciate further examples.

(24) Here, “brazing” is the process of joining two or more metals together with a compatible filler metal by melting and flowing the filler metal into the joint 20. In these applications, the filler material 18 has a lower melting point than the metals being joined, and therefore acts to bind to the joined pipes 10, 16. It is understood that this brazing method differs from traditional arc welding as it does not melt the work pieces to form the union 20. It is further understood that in these implementations, the end condition 12 and support section (shown, for example, in FIGS. 1-3 at 14) provide a heat sink during the welding process. The heat sink of these implementations “pulls,” or otherwise conducts heat to the sharp edge of the material (shown in FIG. 3 at 14A) which is now out of the intended “weld zone,” as would be appreciated.

(25) Since the metal of the filler material 18 has a lower melting point than the base metals being fused (here, as would be shown by the first 10 and second 16 tubes), the filler material 18 typically has less strength than the base metals (of the tubes 10, 16) hence creating a weaker joint than traditional arc welding. It is understood that to overcome this weakness, the American Welding Society created a rule call the AWS 3T rule. The 3T rule holds that brazed weld joints must have at least three times the surface contact as the thinnest material being joined. In doing so, the strength of the filler metal 18 will likely exceed the strength of the thinnest base metal being joined and failure will happen in the base metal 10, 16. As a result of the 3T rule, many applications are not suitable to brazing due to the inability to have three times the surface contact.

(26) However, as shown in the implementations of FIGS. 4-5, the filler material 18 of these implementations is interposed at the joint between the coped tubing 10 and the second piece of tubing 16.

(27) In the implementations of FIGS. 7-9, the jointing system 1 tube 10 features a “straight” end 12. In these implementations, the end 12 of the tubing 10 has been flattened, for example by swaging. It will be appreciated that many other flattening or shaping methods are possible, such that the end 12 is arranged and/or constructed as “flat.”

(28) In the implementations of FIGS. 7-9, the end material (shown generally at 14) is folded inward to form an inwardly extended flange section 14. Rather than having the saddle or coped form of the tubing 10, this flange section 14 presents a planar edge suitable for joining with tubing or pipe having a flat side surface at the joint.

(29) Again, a section of filler material 16 (FIG. 10) is used to form a perpendicular brazed union between the tubing 10 and a second piece of tubing 18 (FIGS. 11-14). The filler material 16 is positioned between the flange section 14 and the second tubing piece 18 at the site of the joint. While the tubing pieces 10 and 18 are held together, heat is applied at a temperature and for a duration sufficient to form the brazed union. The flange section 14 greatly increase the surface contact between the two tubing sections, thereby affording the benefits of the jointing system.

(30) In the system 1 implementations of FIGS. 15-16, an opening 15 can be made in the body of the tube 10, such that a lumen 17 is created therewith. In these implementations, the opening 15 can be constructed and arranged such that a support section 14 is formed around the lumen and at the outer perimeter of the opening 15, as would be understood by one of skill in the art. In these implementations, the tube 10 can be joined to a second tube (not shown) via filler material 18 using brazing techniques, so as to satisfy the 3T rule, as described above.

(31) Another advantage of the jointing system is that it is particularly suited for robotic welding. Robot welders lack the ability to recognize the overheating created in the traditional cope method, nor can it respond and reposition in the way a skilled human can. The folded cope of the jointing system greatly reduces the need to recognize and react to overheating, thereby raising the suitability and reliability of robot welding.

(32) It is understood that the various implementations eliminate the challenge of nonconformance with the 3T rule by processing the tubing or pipe 10 in such a way as to allow for a surface at the support section 14 that can more than accommodate the parameters of the 3T rule. Typical pipe saddles, copes or through holes provide a sharp edge or cross section of material at the point where the joining occurs, and will not allow conformance with the 3T rule since the edge or end of the material gives a cross section that is equal to the thickness of the material.

(33) In the various implementations discussed herein, the material at the end of the tubing or pipe 10 is folded inward to create the support section 14, and therefore a surface greater than three times the thickness of the material 10. In addition, it will be appreciated that these embodiments create conditions for capillary action, which further draws the brazing material into the union or joint 20. To further enhance the weld joint 20, the folded edge of the support section 14 creates a heat sink which causes heat being applied in the brazing process to flow to the sharp inner edge of the material. This heat sink insure proper melting of the brazing material and enhances the capillary action by drawing the flowing material to the hottest point. This action creates a highly repeatable brazing process that meets and exceed the AWS 3T rule. It is also understood that the balance of heat between the two pieces being joined is better equalized and the risk of burning through is greatly reduced.

(34) Among the advantages of the jointing system are that it reduces the cost of creating welded joints, it reduces the skill required to form the welded joints, it increases the strength of the welded joints, and it increases the reliability of forming the welded joints without errors.

(35) Although the disclosure has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosed apparatus, systems and methods.