DE1527819A1 - Process for the manufacture of pipes - Google Patents

Description

The invention relates to a method for producing pipes as a preform for oil field pipes that are internally thickened on the Saiden.

According to known methods, a thick-walled tube blank is piled into a double-sided shape for the production of tubes thickened on the inside at the ends, in which at least one tube end has an outer thickening with a gradual transition to the non-thickened part, the intermediate shape has outside the thickening & ± e wall thickness and the outside diameter of the finished pipe. In a second step, the external thickening is displaced inwards.

An older suggestion is supposed to be the displacement of the thickening inward dttrch skew rolling take place, with a smooth mandrel can be used. After another, also to the booth the proposal belonging to the! technique, this operation should be carried out in a drawing ram using a smooth mandrel.

The main parts of this process are that the outer surface, the tubes are not always sufficiently smooth after skew rolling in the area of the thickening and especially the drawing using a dome opposite each wax process uneconomical 1st.

909849/0353

- 2 -

In addition, it has been observed that the area of the undeserved Rohres, which is adjacent to the incipient thickening, when displacing the thickening inwards with inwards so that in this area especially with thin-walled pipes an impermissible reduction in diameter occurs.

Theoretically, the disadvantage could be avoided if a mandrel which is adapted to the internal shape of the pipe and protruding into the unthickened pipe is used. Because of the difficulty that removed mandrel from the pipe and the impossibility To use this procedure for the production of pipes thickened on both sides, such a proposal is practically unusable.

With the method according to the invention, these disadvantages are avoided. It consists in the fact that the outside diameter of the intermediate form is oversized in the unthickened part and the tube ^{1 is} reduced over its entire length in a second operation by sizing rollers In the pipe works existing facilities a smooth, circular pipe on the outside along its entire length. Handling is simple because it is dimensioned without a mandrel and allows inner wall thickenings to be produced at both pipe ends.

Since the pilgrimage is the manufacture of tubes in the intermediate form not just with thickenings at the ends of the manufacturing lengths but by opening and closing the roller setting during If the rolling is also permitted in other places, multiple lengths can be produced, which may only be made into finished lengths after the sizing rolling be subdivided. The invention thus does not work only qualitative improvements of the pipes produced, but also favors the profitability of production.

In the drawing, the inventive method is on one

9849/0353

Product example explained. It shows a longitudinal section Tube, both ends of which are wall-thickened, as a gate shape for an oil field pipe to be compressed, the process-related one Intermediate form is shown in phantom.

The tube has a continuously cylindrical outer surface 1 on and in the middle greater part of the length a wall thickness a. With transitions 2 close to the wall thickness a delimiting Inner surface 3 cylindrical surfaces 4 on both sides at. The corresponding wall thickness b at the ends is greater than the wall thickness a. For oilfield pipes, the thickness ratio is exaggerated drawn big. "

To produce the preform of the pipe described in Pilger mill made an intermediate form from a hollow shell over a cylindrical mandrel, the diameter of which is shown in dotted lines are. When walking in the direction of the arrow, the roller adjustment is gradually closed from point 6 onwards * until an outer diameter is reached at point 7, which is maintained over the long central part of the pipe. From position 8 onwards, the position is gradually opened again, up to the initial KaS, so that the other end of the pipe is cylindrical from the point 9, The so The intermediate shape obtained is continuously reduced in a sizing mill to the outer diameter shown in solid lines. By inward displacement of the outer wall thickening, the continuously cylindrical surface 10 in the area the pipe ends unzyiindrisch, and it receives the pipe the above designated contour with the two transitions 2. The slight reduction taking place in the middle of the pipe avoids that a visible paragraph is formed at points 7 and 8.

- claim -

. - 4 9 0 9 8 4 9/0353 BAD OHlGlNAU

Claims (1)

Claim Process for the production of tubes as a preform for the Ends of internally thickened oilfield pipes, in which a thick-walled Tube blank in an intermediate shape with an outer thickening at least at one end of the pipe with a gradual transition to the non-thickened part of the pipe and approximately with the finished wall thickness outside the thickening is piled up and in a second Operation the outer thickening is shifted inward by mandrel-less rolling, characterized in that the diameter of the intermediate form in the non-thickened part is oversized Pilgrimage is made and in the second step the pipe is opened its entire length is reduced by measuring rollers. 9 0 9 8 k 9/0 3 5 3 ORiGIMAL,