Metal hose

Corrugated hoses can withstand high pressure and provide maximum leak tightness on account of their material.

It was invented in 1885 by the jewellery manufacturer Heinrich Witzenmann (1829–1906) of Pforzheim, Germany, together with the French engineer Eugène Levavassèur.

The hose was modelled after the goose throat necklace, a piece of jewellery that consisted of interlacing metal strips.

The original design of the hose was based on a helically coiled metal strip with an S-shaped profile.

The result was a permanently flexible, leak-tight steel body of any length and diameter with a high mechanical strength.

From 1886 to 1905, Heinrich Witzenmann continued to develop numerous noteworthy profiles for hose production which are still of technical significance today.

An important variant of the metal hose can be attributed to the inventor Siegfried Frank of Frankfurt, Germany.

Witzenmann had already made experiments in this direction several years earlier, but did not continue his efforts to create a patentable result.

This invention was based on the double-walled, welded, corrugated metal hose (with a wound protection sheath) with radial flexibility.

Metal bellows are created by rolling annular corrugations into a smooth extruded or welded pipe.

Stripwound hoses exhibit enormous tensile and transversal pressure resistance, a high torsional strength and excellent chemical and thermal stability.

The metal hose properties are determined by several factors: the profile shape, the strip dimensions, the material and, if applicable, the type of seal.

The introduction of a cotton, rubber or ceramic sealing thread into a specially profiled chamber during the winding process leads to greater tightness.

Stripwound hoses are frequently used as flexible temperature-resistant and ageing-resistant elements in exhaust equipment, especially in trucks and special vehicles such as tractors.

They are also used as protective hoses for light conductors and electrical lines in fibre optics, or in measuring and control equipment.

The starting material is a seamless or longitudinally welded, thin-walled tube into which corrugations are introduced by mechanical or hydraulic means using special tools.

Corrugated hoses are absolutely leak-tight and are used to convey liquids or gases under pressure or as vacuum lines.

The first step in creating a corrugated hose is to shape the starting metal strip from the coil into a smooth, longitudinally welded tube.

In this case, the hose then passes through a braiding machine that has circumferential wire coil holders, or so-called bobbins.

The flexibility, bending behaviour and pressure stability of corrugated hoses depend on the selected profile shape.

Depending on the use of the hose, special application-specific profile shapes can be implemented Pressure resistance and flexibility can also be altered by varying the wall thickness.

The braiding is firmly connected to the hose fittings on both sides to absorb the longitudinal forces caused by internal pressure.

Hose braiding consists of right- and left-handed wrapped wire bundles that are alternately layered one over the other.