Metal fusion bonding – Process – Using dynamic frictional energy
Reexamination Certificate
1999-05-10
2001-01-23
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Process
Using dynamic frictional energy
C228S119000, C228S212000
Reexamination Certificate
active
06176415
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method and an apparatus for connecting components, such as pipes, rods and similar semi-finished products, by friction welding, in particular for connecting pipes while drilling deep holes and/or for completing holes, for example cavern holes.
DE-A 20 20 121 discloses a method for connecting vertically aligned pipe sections, in which at least one end of the pipe sections to be connected is provided with a chamfer, which acts as a welding joint. A plurality of weld layers are introduced, with the aid of a welding apparatus, into the welding joint formed in this way, in order to connect the components to one another. The welding apparatus comprises a bracket which is mounted on one of the pipe sections to be connected, coaxially with respect to their common longitudinal axis, and a welding head which can be moved on a circular path along the outer casing of the pipe sections to be connected in order to introduce a weld metal into the welding joint, supported and held on the bracket. The welding head is furthermore equipped with means in order to move its horizontal position radially with respect to the external diameter of the pipe sections to be connected.
The solution according to DE-A 20 20 121, which, subject to certain preconditions, appears to be usable on site for the production of pipe systems in deep holes, is very complex from the installation point of view and with respect to the envisaged method technology since a weld filler which can be liquefied must always be used for securely connecting the pipe sections, and a number of weld layers must be incorporated into the welding joint. Furthermore, the setting up and alignment of the welding apparatus involves a further time penalty.
A so-called radial friction welding method, which is improved in comparison with the solution mentioned above, for connecting tubing and casing pipes is disclosed in GB Patent Application 8910118.2.
SUMMARY OF THE INVENTION
Accordingly, it is an object of present invention to provide a method of and an apparatus for connecting components of the above mentioned general type, which avoids the disadvantages of the prior art. The friction heat produced in this way results in the materials of the components involved in the joining process being changed to a plasticized state which can be welded, and a friction-welded connection is produced between the friction ring and the end sections of the pipes to be connected, with the welding ring virtually being rolled into the pipe ends in the region of the connecting point, and producing a cohesive joint.
Welding rings which have to be manufactured specially and are matched accurately to the respective geometric dimensions and materials of the pipes to be connected are required to carry out this radial friction welding method since, once the welding process has been completed, the welding ring is a part of the connection that has been produced, both in terms of the material and geometrically.
Depending on the initial geometry of the welding ring and the specific process sequence, the fact that the welding ring remains as part of the connection can lead to the external diameter in the region of the connecting point being enlarged, corresponding to the level of the welding ring, and with the enlargement being solid, in contrast to the welding and upsetting burr.
If a predetermined external diameter needs to be ensured, this solid diameter enlargement leads to more complex technological measures to remove it than those required to remove the welding and upsetting burr. Furthermore, as a result of the matching of the welding ring to the respective geometrical dimensions of the pipes to be connected, major mechanical efforts are required for reliably clamping and moving the welding ring.
A method and an apparatus for butt-welding of horizontally aligned pipes or the like by heating the contact surfaces to the welding temperature by means of friction heat produced by relative rotation of the contact surfaces with a compression force in the opposite direction active at the same time is already the subject matter of DE-A 23 29 080.
The welding temperature required for the cohesive joint is produced with the aid of a driven metal ring of an appropriate size and thickness which is inserted in abutting contact between the pipes to be connected. Once the welding temperature has been reached, the rotation of the ring is stopped, and a closing compression force is applied between the pipes to produce the welded joint between them and the inserted ring.
This method essentially has the same disadvantages as those described in more detail above. The friction ring which is inserted and driven in order to produce the welding temperature by means of friction heat must be matched to the size and the wall thickness of the pipes to be connected. Furthermore, two weld beads, instead of one, must be produced to connect two pipes. As a consequence, on the one hand, the monitoring of the parameters for the friction and upsetting pressure is required for quality assurance, and the friction and upsetting shortening for the two welding processes that take place at the same time, with separate evaluation, can be achieved only with great effort. On the other hand, this results in increased technological measures to remove the friction and upsetting burr.
Another disadvantage of the last-mentioned method is that the torque which has been transmitted to the friction ring to produce the friction heat must at least partially be dissipated in order to produce the welded connection, before the increased contact force can be applied in order to produce the welded connection.
Various process characteristics, such as the length shortening per unit time, the constancy of the friction moment over a period of time, etc, are normally required to change from the friction process to the welding process (upsetting) for the friction welding of connections as disclosed in DE-A 23 29 080. In addition to recording control variables, relatively complex measured-value processing is required, for example comparison with preset values that are subject to tolerances, are dependent on the joint cross section and material and are generally determined by trial welds before the start of production. All these necessary preliminary activities result in additional effort and costs.
These disadvantages mentioned above have, until now, prevented widespread use of the welding of pipe runs on a drilling tower, as a result of which it has so far not been possible to exploit the benefit of the advantages associated with the welding of pipe connections, such as the improvement in the annular space clearances, reduction in the complexity of pipe runs, flushing, disposal and the like.
SUMMARY OF THE INVENTION
The invention is based on the object of developing a method and apparatus for producing friction-welded connections on components, which can be carried out using process characteristics that can be recorded and determined easily, irrespective of the joint cross section and the materials involved in the friction and welding process.
In accordance with the present invention, this object is achieved by a method which has the steps of using a friction element which is arranged in an abutting position between those ends of the components which are to be connected and is rotated about an axis which is common to the components and to the friction element in order to produce a welding temperature by friction heat with compression forces which at the same time act on contact surfaces between the friction element and the component ends, subjecting the connecting component, for adjoining process, after the rotary movement has been stopped to higher compression forces in opposite directions, after reaching the welding temperature within a virtually steady-state temperature area, continuing the welding process with a material of the friction element being removed on surfaces which are Involved with the friction process, until the ends of the components to be joined come into con
Pittman Zidia T.
Ryan Patrick
Striker Michael J.
Untergrundspeicher-und Geotechnologie-Systeme GmbH
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