Nov. 22, 1932. A. SCHMIDT PROCESS FOR MANUFACTURING BENT PIPES Fig.4.

Filed March 30, 1931 Fig.4.

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Patented Nov. 22, 1 932 ALFRED SCHMIDT, OEPDUSSELDORF,'GERMANY PROCESS FOR MANUFACTURING BENT PIPES Application filed March 30, 1931, Serial No.j 526,514, and in Germany May 31, 1930.

This invention relates to the bending of v pipes such as are used for carrying mediaunder pressure,-f or example, steam, water and the like,in such a manner that during the bending, outwardly projecting or inwardly directed folds are produced, and more particularlyto thebending of such pipesto a. curve of very small radius or the bending'of.

stances these processes give very good results,

but if the pipe to be bent has an unusually thick wall or if the bend to be produced has a very small radius of curvature, for example, equal to the diameter of the pipe, the

. desired results as regards the shape ofthe folds, the shape of the pipe cross-section, and the elasticity of the pipe bend are very often not obtained.

These disadvantages are avoided by using in the manufacture ofthe pipe bend, partly one of the above-mentioned processes and partly a process such as is usual for bending smooth pipe bends, that is, a process in which the pipe is preferably heated over the whole circumference.

My new rocess consists in this that I first bend the pipe in the usual way to a smooth pipe bend of large radius of curvature and 40 then I proceed with the further bending according to one of the processes for making folded pipe bends, so that then the pipe acquires the desired radius of curvature. I may, however, carry out the operatlons in that is, I may first use a process for producing folded pipe bends and afterwards one of the usual processes for producing smooth pipe bends. I may also use simultaneously the process which 1s usual for producing folded pipe bends and that folded pipe -rying out the process.

which is usual for producing smooth pipe bends, the parts where the folds are to be formed belng strongly heated and the other parts of the pipe walls being heated less strongly. I The heating of the folding places may be effected successively or also simultaneously for all the folds, or for individual groups of folds. Experiments have shown that by the use of my new process even with thick walled pipes or with small radius of curvature a bend is obtained which is quite satisfactory as regards shape of the folds and the cross-section of the pipe. The accompanying' drawing illustrates examples of car- Figs. 1-3 show the 'process 'in which jfirst a smooth pipe bendand then from it afolded pipe bendf'ismall radius urvature (r= D) is 'produced'f Figs. 46 illustrate .tlf' anufacture of the same pipe bend, the'folds first being rodnced on the pipefthenf the pipe being ent according to the usual process for making smooth pipe bends. In Fig. 1 a. pipe filled with sandis secured .at 1.- The part between the lines 2 and 3 is heated on all sides and then a tension is applied at 4, so that the pipe is bent in the shape shown in Fig. 2.

After cooling, the parts 5, 6, 7, 8, of the inner side of the curvature are'heated successively and after each heating an outwardly projecting fold is produced by a tension at 4. i The pipe bend shown in Fig. 3 is thus obb5 tained.

Fig. 4 shows the same pipe filled with sand as Fig. 1. The parts 9, 10, 11, 12, are heated successively and after each heating a tension is applied at 4, the folds 13, 14, 15, 16, (Fig. 5) are then formed, while the heated parts bend. The part of.the pipe between the lines 17 and 18 is then uniformly heated and brought into the shape shown in Fig. 6 by further tensionat 4.

In the same manner pipe bends with inwardly projecting folds may also be produced.

What I claim is:

A process for bendmg pipes which are suit; 100

able to withstand internal pressure, comprising filling the pipe with sand and securing it,' heating the whole circumference of the part to be bent and partly bending it a11ow- 5 mg the pipe to cool, eating individual parts of the pipe Walls on the inside of the bend, and bending the ipe a small amount after each heating until'the desired shape is obtained.

1a In testimony whereof I have signed my name to this specification.

ALFRED SCHMIDT.