DE472415C - - Google Patents

Description

GERMAN EMPIRE

ISSUED FEBRUARY 27, 1929

REICH PATENT OFFICE

PATENT LETTERING

CLASS 49h ² GROUP 24

B 123981 I [4 <? H * Date of the announcement - about the grant of the patent: February 7th / gsg

Rudolf Böhling in Hamburg-Steinwärder and Rohrbogenwerk G.m.b.H. in Hamburg

Process for the production of elbows, pipe coils, etc.

Patented in the German Empire on February 9, 1926

According to a known method (patent 367 518) pipe bends, pipe coils etc. produced with a small radius of curvature in that the straight pipe workpiece is bent by eccentric expansion. This method in which a mandrel with an eccentric ring section is used, which is the continuation of the eccentrically gradually increasing in cross-section one end of the straight mandrel shaft is for production of pipe bends etc. with every radius of curvature applicable to every pipe diameter and results in all If the wall thickness of the pipe bend is uniform, the wall thickness is the same as that of the pipe workpiece.

The uniform wall thickness is one of the

intended effects from the eccentric

»O see widening; the latter requires one Part of the effort required to advance the pipe workpiece on the mandrel.

Now it is in many cases of use

the pipe bend is completely harmless if the

«5 wall thickness on the outside of the curve, that is, at the back of the pipe bend, is lower.

So if for such cases of use the pipe bends according to this known method

are produced, a costly effort arises unnecessarily.

The aim of the invention is to produce pipe bends with a wall thickness weaker at the back without the unnecessary effort mentioned, but still with a small radius of curvature, to manufacture. It is known, however, to produce elbows in that the beforehand is bent in its entire circumference heated pipe work piece and cooled during the bending on the inside of the curvature. This method does not allow the production of pipe bends with a strong curvature or with a small radius of curvature, because the cooling cannot be sufficiently effective against the heating. According to the invention, this is before unheated pipe work piece during the bending process on the inside of the bend strongly cooled, but at the same time heated on the outside of the curve. As a result of this A strongly opposing treatment of the pipe workpiece on the inside of the curve and on the outside of the curve can be a Bending takes place on the outside with strong stretching and on the inside with little compression. But that makes it possible a strong curvature, with the formation of wrinkles, which would otherwise be considerable would occur as a result of the cooling, which is very opposite to the heating of the outside is prevented.

With this large temperature difference between the inside and the outside during the Bending is the use of a well-known one consisting of a straight part and a ring

cut of the same cross-section of existing mandrels »required. The latter results in the smaller radius of curvature particularly necessary all-round internal support of the emerging Pipe bend and ensures the exact execution. Until now, such a dome has only been used during manufacture of pipe bends with a large radius of curvature and a relatively small one Pipe diameter. *

The invention lies in the expansion of the pipe work piece, which requires expenditure of force to avoid the underlying idea behind the occurrence of the small radius of curvature to bring about the necessary strong curvature of the pipe work piece that the pipe building material on the inside of the curvature slightly compressed, but strongly stretched on the outside of the curvature. The slight upsetting a wrinkle formation on the inside of the curvature avoided, while by the relatively strong stretching which causes strong curvature.

About this compression and stretching in order to achieve a small radius of curvature To enable the required ratio, according to the invention, using a dome with a cylindrical ring section of the same or smaller cross-section as that of the mandrel shank when advancing of the Rolir work piece over the mandrel t-ine strong cooling of the pipe work piece the inside of the curve, but heating is carried out on the outside of the curve. The cooling of the pipe work piece on the inside of the curve is particularly important because it has the consequence that the pipe building material is only slightly compressible.

The heating of the pipe workpiece on the outside of the curvature, however, is made possible

Claims (2)

Claim: Cb that the pipe workpiece bends under great stretching on its outside of curvature in the manner prescribed by the ring segment of the mandrel. As can be seen from Fig ι of the drawing, the cooling can be effected by very strongly cooled air, which is passed through a nozzle α against the inner curve of the pipe workpiece b or of the ring section c of the dome. An acetylene or compressed gas flame is directed through a nozzle d against the outside of the curvature and thereby the pipe workpiece is strongly heated here. Mach Fig. 2 and 3 an approximately semi-cylindrical chamber c is provided which surrounds the pipe work piece b at the ring section e on the inside of the curvature in a suitable length he stretching of the pipe work piece. In this chamber e is as shown in Fig. 2 Cold air or cooling water continuously introduced and discharged from her. In certain cases it may be sufficient if chamber e is filled with a highly effective heat dissipation agent (Fig. 3.1. The outside of the curvature can also be heated by some other type of heating, for example by a furnace. Process for the production of elbows, Coiled tubes, etc. using a cross section which is the same as a straight part and a ring section best rush the domes, thereby being able to indicates that the unheated agitator piece during the bending process to dci The inside of the curve is strongly cooled and at the same time on the outside of the curve is heated. For this purpose ι sheet of drawings