DE2457392A1 - Friction welding pipelines together - using external annular projections so a smooth bore is obtd. - Google Patents

Abstract

In this process of joining two hollow parts, each part is provided with an annular groove on the end surfaces which are to be welded together; due to this groove, the end surfaces consists of two coaxial rings and the outer ring on both parts e.g. tubes, projects so that, at the start of welding, the two outer mating surfaces are upset in the welding process the material can expand into the groove until the two inner surfaces come into contact, this contact terminating the process. The welded joint and the inner contact surfaces can be in the same plane or offset w.r.t. each other. The method is esp. applicable to welding tubes for under-sea pipelines. No upsetting occurs in the bore of the tube, the result being that a smooth, aligned bore is obtd.

Description

Method of making a connection by friction welding The invention relates to a method for joining hollow parts by friction welding, e.g. for joining the ends of two pipes together and also relates to design the hollow bodies that are to be joined together.

In particular, the invention is also applicable to those applications directed, in which a smooth inner bore after the welding process without further Machining operations is desired.

It was earlier, on pages 13 and 14 of a publication Company's "Principles of Inertia Welding" Caterpillar Tractor Company from 1969 proposed the where an outer annular shoulder is resistance welded to a first workpiece (inertia friction welding) with an abutting surface of a second workpiece is to be connected, which has an opening through which an internal, The smooth end of the first workpiece engages a recess on the first workpiece can be arranged around the upset and bent metal on the inside the shoulder and isolate it.

When the two hollow workpieces that are joined together, to form a pre-combustion chamber, each other through the smooth inside Overlapping the end of one workpiece can be an edging or pocket between the overlapping surfaces formed at the intended welding point will. However, these measures lead to an internally stepped bore, the recording and isolation of the internal compression material, however, poses problems when the two hollow bodies are joined at their ends without internal overlap should be and have a smooth inner bore with a constant diameter should.

According to the invention, each of the surfaces of the hollow bodies, whose Ends are connected to each other, formed with an annular recess, extending rearward from said surface. The annular depressions have essentially the same diameter so that they fit one another, when the ends of the workpieces touch each other. And each of the end faces will be with first and second mating annular members are formed which are coaxial to the annular recesses on the two workpieces or outside and inside the annular depressions lie. The first annular parts have a such axial extension relative to the second annular parts, # aß there is initially a gap between the second annular parts when the first annular parts are brought into initial contact.

The method according to the invention takes place during friction welding (friction welding) or Preßscilweißens a relative friction movement of the end faces the hollow parts under-axial pressure until the first annular parts in axial Direction have been shortened by upsetting to a predetermined degree, the is less than the initial gap between the surfaces of the second annular Parts. The relative rubbing movement is then finished and one in axial Direction of compressive force applied for melting and forging or upsetting, to cause a further axial shortening of the first annular parts until the Surfaces of the second annular parts touch each other or only through a previously inserted sealing element are separated, whereupon the jointing causing pressure is no longer maintained.

Basically, the frictional movement is a relative rotation the hollow body, but there is one angularly limited vibration and one Circular motion can be used instead of relative rotation in some cases.

In this way and at the same time, what is inside, due to the Friction welding or pressure welding compressed material of the first annular parts received by a chamber defined by the two annular Depressions is formed and is in this way from the interior in the bore of the hollow body through the contacting surfaces of the second annular l'e: Le isolated or separated. If there is no relative rotation below Contact takes place between the surfaces of the mating second annular parts, there is also no thermal compression. The second annular parts effect an upsetting or melting stop, which is used to control and monitor the upsetting and melting local deformation is effective. This is in contrast to the pressure control that is used continuously during the melting process of friction welding processes or in pressure welding, in which the amount of deformation depends on the developed Heat depends and therefore on the mechanical resistance of the workpiece the upsetting or melting pressure.

In the method according to the invention, a predetermined amount is used required for a melt deformation on the matching first parts.

From the following description it will be understood that the ends of the components are shaped so that in a one-piece design a receiving the upsetting material Chamber and a stop that limits the sequence of movements during upsetting or melting is created.

The invention is particularly advantageous when welding together Pipes that form an undersea pipeline.

Because of the forces that occur in a pipeline when the pipe sections on the ship in the horizontal direction and then the pipeline laid in an "S" -shaped line, it has been suggested that the pipeline pieces join in a vertical direction so that they line up in a ~ C "line embarrassed. The process of friction welding or pressure welding is a known method that is used when welding pipes with their Ends are arranged in the vertical direction to each other, as the connection in one A single welding process can be made because gravity is not a problem and because this procedure can be carried out quickly. It can but can only be used if you also get a smooth inner bore.

Where the compression material located on the inside is receiving The chamber can come into contact with the material in the pipeline, it is advantageous to provide a sealing device, for example a sealing washer or to place an O-ring in the space between the second annular surfaces, so that these second annular surfaces against the seal pressed when the upsetting or welding pressure starts or becomes effective.

Around the annular recess and the faces on either side of it adapt to each other, while the holes should remain the same, the Ends of the tubes are thickened, expanded or compressed. The flared end can be a separate annular part that is attached to the ends of the tube in any welded to a special operation, or it can be the result of a Be upsetting process. The outer surface or any other area of the flared Area can be designed to allow them to be friction welded is clamped and compressed sufficiently. The resulting connection area should then be at least as large as the nominal area or the nominal area of the hollow parts.

If desired, another annular chamber and a Another ring-shaped forging process that retards the upsetting and forging process Stop can be placed outside the annular surfaces by friction welding connected, so that that too outside bending away compression material is received in a chamber formed by the annular depressions will. Thus, this material is also isolated or isolated by the pressure stop surfaces. apart from the rest of the parts.

Another option is between two fixed ones Pieces of piping provide a rotating insert, each pair of butting Areas designed as described above, if desired, can be used with be provided with an outer surface or with an outer contour that allows it is set in rotation. For example, the outer contour can be such that the insert has a hexagonal cross-section.

Instead of a relative rotation, angular vibrations of the workpiece can also be used or circular motions can be used in some cases. With the circular movements different movement processes are conceivable. It is especially so in such cases also possible that the axis or the center of the circular movement does not coincide with the The longitudinal axis of the bodies to be connected coincides.

The process according to the invention can also be carried out under water. In such a case it is beneficial to use the characteristics of the British floating Patent application no. 41594/72 to use, according to which a sleeve tightly around the abutting Grips ends of the workpieces to keep the water away from the weld zone. Of the The material of the sleeve has properties such that it can withstand upset deformation the body to be welded does not offer any resistance during the welding process and can be locally displaced, displaced or displaced when the deformation the body is made in the manufacture of the fixed end seal, the sleeve or sheath can for example be made of polystyrene foam.

For a better understanding of the invention, some pipe ends, such as they are formed before the welding process and the corresponding parts after Welding illustrated in the accompanying drawings. They show: Fig.1A, 2A and 3A pairs the pipe ends before welding and Fig. ##, 2B and 3B the corresponding ones Pipe ends after welding.

In each of the illustrated embodiments are on top of each other adapted annular recesses 11 and 12 formed in those surfaces which are joined together and the annular surfaces 12 and 13 are those Surfaces of the first mating annular parts according to the above Description, i.e.

those surfaces joined together by friction welding will. The annular surfaces i4 and 15 are the surfaces of the second annular Parts of the above description and serve as a stop when melting together.

As can be seen from FIGS. 1B, 2B and 3B, the annular Wells 10 and 11 form a chamber 16 which holds the inwardly compressed material 17 of the welded pipeline, so that the bore of the pipeline a has a smooth surface without a change in diameter at the junction.

As shown in Figure 2A, there is a chamfer or beveled surface 18 on the exterior the front end of the ring collar 15 is provided and serves as an insertion or centering surface, when the surfaces 14 and 15 approach each other.

In FIG. 3A, a sealing ring 19 is shown, which rests against the surface 14 and between surfaces 14 and 15 is squeezed when the pipeline is welded together. In addition, surfaces 20 and 21 are on the pipe ends inclined according to Fig03A, which allows for better alignment of the workpieces during of the friction welding process contributes.

By creating recesses on both workpiece surfaces, it is ensured that the flow of the pushed away resp.

compressed material into the chamber formed by the depressions is not blocked by the shortening of the workpiece, as would be the case if the recess would only be formed in a workpiece.

Common to the embodiments shown in the figures, that the pipe end pieces 1 and 2 have a constant inner diameter and on their free ends are designed in such a way - that chambers or pockets during welding 10 and 11 arise into which material is able to flow.

To create these chambers 10 and 11, the free ends of the Pipe end pieces # different -shaped, as a comparison of Fig.1A, 2A or, 3A results, According to Fig bigger Outer diameter pipe end pieces 1 and 2 from coaxially spaced from each other lying, inner and outer ring collar 3 and 4 or 5 and 6, the outer Ring collars 5 and 6 overlap the inner ring collars 3 and 4 or in the axial direction protrude further. When the tubes are welded, the outer ring collars 5 and 6 first on top of each other and deform, as can be seen from Fig.1B.

Material flows both to the outside and to the inside of the pipe, however, it is located between the annular collars 3 and 5 or 4 and 6 Depressions or annular grooves 10 and 11 respectively, which form an annular chamber 16, if the inner ring collars 3 and 4 also abut one another.

These annular collars 3 and 4 are used with their free radial surfaces 14 and 15 as stops that further deformation of the outer annular collar 5 and 6 prevent.

The opposing, radially directed free boundary surfaces the outer ring collars 5 and 6 are denoted by 12 and 13 in FIG.

In the embodiment shown in Figure 2A, only that an end piece 2, an outer ring collar 6 and an inner ring collar 4, while the end piece 1 of the other tube is stepped inside. The two ring collars 4 and 6 of the embodiment according to FIG. 2A have in radial Levels lying free boundary surfaces or annular surfaces 15 and 13, which with corresponding Surfaces 14 and 12 of the other pipe section 1 interact. The ring collar 4 overlaps also the ring collar 6 and thus protrudes over this in the axial direction. At the free end of the ring collar 4 is finally still on its outer circumference Chamfer -18 provided for easier insertion and centering of the two pipe ends serves. The collars 4 and 6 are in turn tm spaced from each other, so that an annular chamber 11 is formed between them.

The end piece 1 of the embodiment according to FIG. 2A is as already said internally stepped, so that inside an annular surface extending radially from the bore # 14 and axially and outwardly offset one with the annular collar 6 of the other pipe end piece 2 cooperating annular surface 12 are formed. This is preferably done using a annular step 7 between the annular surface 14 and the at its free end Ring surface 12 supporting outer ring collar 5 of the end piece 1o The bevel 18 on the End piece 2 hits the ring edge of step 7 when the tubes are pushed together and is guided by it.

The embodiment shown in Figures 5 and 3A has just like the embodiment shown in Figure 1A at the end piece 1 an inner ring collar 3 and an outer ring collar 5, the the inner ring collar 3 overlaps in the axial direction, the other end piece 2 of the The embodiment shown in Fig.3A also has two in radial Spaced annular collars 4 and 6, the inner annular collar 4 overlaps the outer ring collar 6 in the axial direction and also directly forms the bore of the tube or of the end piece 2 of the tube. Between the two Ring collars 3 and 5 or 4 and 6 are in turn annular recesses 10 and 11. Congruent annular surfaces 12 and 13 delimit the annular collars 5 and 6 and meet when the pipe ends are welded together, these being like Deform shown in Fig.3B.

The inner surface 8 of the annular collar 3 of one end piece 1 runs widening conically from the inside to the outside and with a correspondingly conical effect shaped outer surface 9 on the other ring collar 4 together, the ring collar 3 forms therefore not the hole in the area of the end piece 1, but the ring collar serves for this purpose 4 of the other end piece 2, which engages in the end piece 1. The ring collar 4 can with its free end or with its annular front 4 impact surface 15 to reach into the end piece 1 until it reaches one of the bore in the radial direction outgoing, annular stop surface 14 meets, to which the conical surface 8 of the collar # 3 adjoins.

In front of the stop surface 14 of the end piece 1, a sealing ring 19 or the like, which are deformed when the ring collar 4 hits can, as can be seen from Fig. 3B.

The three illustrated and described exemplary embodiments show that the basic idea according to the invention can be varied in many ways. Essential is only that the pipe end piece is not deformed in the immediate area of the bore will. The parts located there must therefore be designed as stop surfaces and later when the workpieces move towards one another meet than the parts to be welded directly. With the one described first Embodiment, this is achieved in that both outer ring collars the inner Overlap the ring collar. In the second embodiment, the dimensions are chosen so that the outer Ringkragexl 5 and 6 with their annular surfaces 12 and 13 much more likely to hit each other than -the stop surfaces 14 and 15, which are directly proceed from the hole. That the same applies to the exemplary embodiment according to Figures 3A and 3B.

Finally, in all of the exemplary embodiments, at least one has End piece two radially spaced annular collars 4 and 6, see above that when joining the end pieces 1 and 2, an annular chamber 16 is formed in which the inwardly pushed material 17 can flow. Because the inner ring collar 4 always with its inwardly directed cylindrical wall the bore of the pipeline forms, affects the compressed or

material 17 flowing away, which originates from the outer ring collars 5 and 6, no longer the evenness of the bore of the pipeline in the area of the connection point.

The invention is not limited to the exemplary embodiments shown in the figures limited, but further changes can be made without this deviates from the basic inventive concept.

For details on how the heat is generated during welding has to be, has not been discussed in more detail, since this is fundamentally to the person skilled in the art is known.

Claims (8)

Expectations: 1. Method of joining hollow parts by friction welding, two hollow parts being prepared to be joined together with their ends to be, characterized in that each of the end faces with an annular Recess is formed which extends rearward from the end face, that the annular recesses in the two end faces are substantially the same Have diameters so that they fit together when the hollow bodies move with their ends touching that each of the end faces with first and second, one on top of the other matching annular parts are formed which are coaxial with the annular Depressions on the two workpieces or outside and inside the annular Depressions lie and that the first annular parts are so far in the axial Direction relative to the second annular parts that first extend a Gap between the second annular parts exists when the first is annular Parts come into contact. 2. Hollow, for connection to each other by the method according to claim 1 certain body, characterized in that the second annular part is on each end face has a recess with respect to the first annular part. 3. Body according to claim 2, characterized in that the second annular part on one of the end faces relative to the first annular part whose end face protrudes. 4. Body according to claim 2, characterized in that in addition a further annular recess outside said first annular part is provided and a further annular part outside the further annular Recess that the axial extent of the further annular parts is such, that there is initially a gap between them when the first annular parts get in touch. 5. Body according to claim 3, characterized in that the second Bing-shaped part that goes over the first annular part with respect to its end face protrudes, an inclined surface for cooperation with a has a corresponding inclined surface of a recess which is used to second annular part to guide the other end face and that the inclined Surfaces serve to the interconnected hollow body in the axial Direction to lead or to center and to coordinate when the welding process takes place. 6. A method for connecting two hollow bodies according to the claims 1 to 5, characterized in that the hollow bodies are friction welded to one another are connected and that an axial shortening of the first annular parts takes place until the second annular parts-each other touch or only separated from each other by a previously inserted sealing element are, 7. Method of joining the ends of a first and a second hollow Body by friction welding or pressure welding, characterized in that every of the end faces of said bodies formed with an annular recess extending rearward from said end face that the annular Wells have essentially the same diameter, so that they are on top of one another fit when the workpieces touch each other with their ends and that the End faces are shaped so that the first mating annular Parts outside the annular depressions on the two workpieces are in this way far in the axial direction relative to the second, mutually matching annular Share in the matching annular recesses on the two workpieces that when the surfaces of the first annular parts are friction welded initially come into contact with each other a gap between the surfaces of the second annular parts consists that the hollow body thereupon a frictional movement relative are exposed to each other under axial pressure until the first is annular Parts in the axial direction by upsetting and flowing away of the material up to one have shortened a predetermined amount that is less than the initial gap between the surfaces of the second annular parts and that the relative Rubbing movement then stopped and an axially directed fusion-welding pressure is applied, to cause a further axial shortening of the first annular parts, to the second ring-shaped parts touch each other or only by a previously inserted one Sealing element are separated, whereupon the fusion-welding pressure is no longer upright is obtained. 8. The method according to claim 7, characterized in that the relative Frictional movement is a relative rotational movement, 90. Method according to claim 7 or 8, characterized in that the second hollow body is an insert between the first hollow body and a third hollow body is arranged that the abutting end faces of the second hollow body and the third hollow Body with matching annular depressions and matching annular parts similar to those abutting end surfaces of the first and second hollow body are formed and that the second hollow body is relatively to the first and third hollow body is moved to a corresponding by friction To generate heating of the abutting surfaces and through this Welds or welds created by friction between the first and to form the second and between the third and third hollow bodies.