| 摘要 |
A heat exchanger is proposed in whose connecting flanges there is contained at least one threaded blind bore which has a bottom which is at least approximately flat. For this purpose, a drilling (boring) tool which has an at least approximately flat end face and thus a point angle approximately between 150@ and 180@, is used to drill the hole to be drilled to a desired length and as deep as possible and so as to produce a bore hole with a flat bottom in the process. After this, the thread is cut in using a tap which has a flat end face and a cut start which leads over from there to the cut thread and amounts to approximately 1 1/2 of the thread. The result is threaded bores of the greatest possible depth in the flanges in conjunction with a small flange cross-section.
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