MXPA98007195A - A method of friction welding to join tubula members - Google Patents

Abstract

The present invention relates to a friction method by welding two tubular members at one end to an end relation including the following steps of: providing one end of each tubular member to be joined with a molded portion, the molded portion having a first surface which is substantially perpendicular to the radius of the tubular member and a second surface at an obtuse angle to the radius of the tubular member, so that when the ends when being joined are brought into contact with each other, the shaped portions define an anal three sides, placing a ring-shaped member in the channel, the ring-shaped member having a radius that is greater than the radius of the first surface and less than the radius of the outer walls of the tubular members, and at least one inner portion of the annular shaped member having a cross section; and, rotating the ring in relation to the tubular member and subsequently compressed the ring, to bring the ring with the shaped portions of the tubular members to form a friction weld that welds the tubular members together in an end-to-end relationship

Description

A METHOD OF FRICTION WELDING TO JOIN TUBULAR MEMBERS The invention relates to a friction welding method and in particular, a radial friction welding method, for welding two tubular members in end-to-end relationships. Conventional methods for welding together tubular members, such as tube flange lengths, in end-to-end relationships, have involved arc welding by a skilled operator. Such welding consumes time as the weld progresses circumferentially around the joint in the tubular members. In addition, traditional welding techniques involve melting the metal of the tubular members, which may not be suitable for bimetallic tubular members, and melting the material can result in numerous metallurgical problems. In addition, it may be necessary to carry out the welding operation in an inert atmosphere, to prevent or minimize the oxidation of the metal of the tubular members. Welding of tubular members in a suggested end-to-end relationship has been radial friction welding. This method involves beveling the ends of the tubular members to be joined, so that when the ends are placed together, there is a V-shaped cavity extending circumferentially around the joint. A V-shaped ring located in the V-shaped profile, formed by the adjacent ends of the tubular members, is then rotated at high speed and compressed to bring it into contact with the V-shaped ends of the tubular members to form a friction weld, to weld together the tubular members. However, in practice it has been found that this friction welding method of tubular members has a tendency for the weld to be defective, since the weld tends to form a bridge above the junction of the tubular members, and ds1 as a result a defect in the weld on the internal surface t of the tubular members. This is a particular problem where it is intended that the tubular members transport fluids, for example, the tubular members that are part of a pipe. Due to these problems, the joining of tubes by radial friction welding has not been widely used. According to the present invention, a method for frictionally welding two tubular members in an end-to-end relationship comprises providing the end of each tubular member to be joined with a formed portion, the formed portion having a surface, which is substantially perpendicular. to the radius of the tubular member, and a second surface, at an obtuse angle to the radius of the tubular member, so that when the ends to be joined are brought into contact with each other, the formed portions define a three-sided channel; locating an annular member having a quadrilateral transverse section in the channel, the annular member having a radius, which is greater than the radius of the first surface and smaller than the radius of the outer wall of the tubular member, making rotating the ring in relation to the tubular members, and subsequently compressing the ring, to bring the ring into contact with the formed portions of the tubular members to form a friction weld, which welds the tubular members in an end-to-end relationship. According to another aspect of the present invention there is provided an annular member for frictionally welding two tubular members in an end-to-end relationship, wherein the tubular member has a quadrilateral cross section. The invention has the advantage that by having a channel with a surface that is substantially perpendicular to the radius of the two tubular members, and to the compression force applied to the ring, it is possible to frictionally weld two tubular members in an end-to-end relationship and reduce to the mini or the possibility of defects in friction welding. Preferably, the annular-shaped member has a substantially trapezoidal cross-section, and the trapezoidal cross-section of the annular-shaped member, is of a shape generally similar to the shape of the cross-section of the channel formed when the formed ends of the tubular members are taken to end-to-end relationships. Typically, the ring-shaped member is of the same material as the tubular members to be welded in an end-to-end relationship. Preferably, the tubular members and the annular shaped member are formed from a metal. Typically, where the tubular members are bimetallic, the ring-shaped member may also be bimetallic. Preferably, a support member is inserted into the tubular members to support the ends of the tubular members during frictional welding. Typically, the support member is expandable to contact the inner surfaces of the tubular members. Now, examples of a radial friction welding method according to the invention will be described with reference to the accompanying drawings, in which: Figure 1 is a partial perspective view of the cross section showing the tubular members being friction welded; Figure 2 is a cross-sectional view through the apparatus shown in Figure 1, before welding; Figure 3 is a cross-sectional view through the tubular members when they are in an end-to-end relationship, before being welded and with an internal ring and mandrel omitted; Figure 4 is a cross-sectional view through a ring for use in the friction welding operation shown in Figure 1; Figure 5 is a cross-sectional view through two bimetallic tubes in an end-to-end relationship, before being friction welded; and, Figure 6 is a cross-sectional view through a bimetallic ring, for use in the friction welding of bimetallic tubes, shown in Figure 5. Figure 1 shows two tubes 1, 2, which have their ends 3, 4 in contact with each other. An internal expansion mandrel 5 is located inside the tubes 1, 2 and expands until it comes into contact with the internal surface of the tubes 1, 2, adjacent to the ends 3, 4.

A ring 6 is located around the tubes 1, 2 and the inner portion of the ring has a lower surface 16, and two side surfaces 7, 8, which are located in a channel 9 defined by the portions formed on the ends 3, 4 of the tubes 1, 2. The channel 9 is shown in more detail in Figure 2, where it can be seen that each of the tubes 1, 2, have their respective ends 3, 4, provided with a portion formed, the which comprises a surface 10, which is substantially parallel to the surface 16 of the ring, and substantially parallel to the internal surfaces 11, 12; of the tubes 1, 2. Extending from the surfaces 10, there is an angular surface 13. As shown in Figure 3, the angle alpha is the angle between two surfaces 13, and the angle alpha is greater than the angle beta ( see Figure 4), which is the angle between the side surfaces 7, 8 on the ring 6. In a typical example, the angle alpha can be 50 °, and the angle beta can be 45 °. The total length of the surfaces 10 when joined, is indicated by the dimension "L" in Figure 3, and is approximately equal to the width of the surface 16, indicated by the letter "F" in Figure 4. Typically, the Dimensions L and F are approximately 4 mm. The depth of the material between the surfaces 10 and the internal surfaces 12, 11 is indicated by the letter MR "in Figure 3, and can typically be about 2 mm.These dimensions and configurations are typically angles and dimensions for the tubes 1, 2 having a diameter of 169.3 mm and a wall thickness of 14.3 mm The ring 6 can have a depth, T "(see Figure 4) of an internal diameter of approximately 145 mm, a diameter external of approximately 194 mm and a thickness of approximately 24.4 mm. In use, the ring 6 is rotated at high speeds and then compressed in contact with the surfaces 13, 10 of the channel 9, to cause heating of the material on surfaces 7, 8, 16, 10, 13, by friction generated by the ring 6 in contact with the surfaces 13, 10, as the ring 6 rotates with respect to the Lubos i, 2. After it has generated sufficient heat, the ring is compressed with a forging force for welding the ring to the tubes 1, 2 and welding the tubes 1, 2 in an end-to-end relationship. The invention can also be used to weld bimetallic tubes, such as the tubes 20, 21 shown in Figures 5, 6. The tubes 20, 21, comprise an inner metallic layer of a first metal 22 and an outer metal 23. In this example , a bimetallic ring was used , which also comprises metal 22 on the inner surface, and metal J on the outer surface.

Claims (1)

1. CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following: CLAIMS, i. A friction welding method for joining two tubular members, in an end-to-end relationship, characterized in that it comprises providing the end of each tubular member to be joined, a portion formed, the formed portion having a surface, which is substantially perpendicular to the radius of the tubular member and a second surface at an obtuse angle to the radius of the tubular member, so that when the ends to be joined are brought into contact with each other, the formed portions define a three-sided channel; locating an annular member having a quadrilateral transverse section in the channel, the annular member having a radius that is greater than the radius of the first surface and smaller than the radius of the outer wall of the tubular member, rotating the ring in relation to the tubular members and subsequently compressing the ring, to put the ring in contact with the formed portions of the tubular members, to form a ring. 7. The method according to any of the preceding claims, characterized in that it further comprises inserting a support member into the tubular members to support the ends of the tubular members during frictional welding. 8. The method according to claim 7, car c pri or or? The support member is inserted into the tubular members and expands until it comes into contact with the internal surfaces of the tubular member. 9. An annular member for frictional welding two tubular members in end-to-end relationship, characterized in that the annular member has a quadrilateral transverse section. The ring-shaped member according to claim 9, characterized in that the annular-shaped member has a trapezoidal cross-section.