DE860035C - Process for the production of clad tubes and tubular bodies - Google Patents

Description

Process for the production of clad pipes and tubular Bodies The manufacture of clad pipes, e.g. B. of steel pipes, with an inner or external or bilateral copper pull usually takes place in the way, that the steel pipe with the cold way possibly placed over one in between Soldering layer brought to bear on the plating on the welding or Soldering required temperature is heated. To .den for a good bond between the metal layers indispensable contact pressure during the welding or soldering process the difference in the thermal expansion coefficient of the base metal and the cladding To ensure this, additional measures are required in most cases.

For this purpose, Miau subjects the heated pipe to a roller or roller Drawing process or placing it in a concentric manner during heating, the cladding layer pressing pressure .by indifferent means .aus. Only in the case of inner plating a steel pipe with copper or another metal with the same high coefficient of expansion can refrain from such measures, as the copper pipe due to its higher thermal expansion coefficients stronger when heated Alis seeks to expand the steel pipe and thereby creates a contact pressure itself.

With all previously used or proposed Plattfer processes of this type, the tubes deserve warmed up in their entire length and for a longer period of time Temperature held.

In contrast, according to the invention, the production of clad is made Pipes made in such a way that the for welding or soldering of the full abutting Layers necessary heating progressively in a localized annular shape Zone takes place briefly. The heating can be done either from the inside or from the outside will. This inevitably results in a temperature gradient in the pipe wall, while the previously known - processes strive for temperature equalization. at Application of the method according to the invention are each only in a narrow Zone: the temperature conditions required for welding or brazing have been reached, while in front of and behind this wandering heat zone a good support effect is ensured ice.

A major advantage of the new process is that it does not rely on the use of the usual heating ovens, the pipes in their the entire production length and in which a lot of heat and time are wasted must be expended. Whereas when heating in such ovens only an intermittent one Operation is possible, the new process easily fits into the usual production process of the pipes, e.g. B. the production, by pulling a.

Heating from the inside has proven to be particularly advantageous, where z. B. for the outer plating result in the following proportions: The steel pipe expands more than the inside out due to the temperature gradient less highly heated copper jacket, so there was from the beginning of heating to re-cooling after welding or soldering, the copper pipe is always pressed against the steel pipe; the greater coefficient of expansion of copper is due to the lower temperature of the copper mandrel compared to (the higher heated steel inner pipe so compensated, that the contact pressure required for welding or soldering is always available. Until now it was not possible to produce an external copper layer by soldering, because the solder is one-sided due to the peeling of the plating with the usual heating converges. Place when using the new internal plating process also find the most favorable conditions; because of the temperature gradient from the inside to the outside the contact pressure of the Inner copper tube is further increased.

If with less coordinated materials or with unsuitable wall thicknesses the inevitably occurring contact pressure is not sufficient, this can be caused by rdem Downstream burner tools or measures that increase the contact pressure, e.g. B. with the help of drawing processes through dies reducing the outer diameter or with plugs that enlarge the inside diameter. The same Effect can be achieved by cooling the pipe in a ring from the outside behind. The heated Zone can be achieved.

The process can be used with all materials that are through Soldering, pressure welding or diffusion welding can be connected to one another, indifferently whether the cladding is carried out on the pipe or on the prefabricated product.

Claims (4)

PATENT CLAIMS: i. Process for the production of clad pipes and tubular bodies, characterized in that iie for welding or Soldering necessary heating progressively in a localized ring-shaped Zone takes place briefly. 2. The method according to claim i, characterized in that the heating is preferably carried out from the inside. 3. The method according to claim i and 2, characterized in that the contact pressure immediately adjoins the heated zone is mechanically reinforced. 4. The method according to claim i to 3, characterized in that that - in connection with the heated zone, cooling takes place from the outside.