DE1210982B - Process for the production of a high pressure hose - Google Patents

Description

Method of making a high pressure hose The invention relates to a method for manufacturing a high pressure hose consisting of from a tube made of synthetic rubber, a tubular one placed on the tube Braiding made of high-strength steel wire and a tubular sheath made of synthetic rubber, in which the vulcanized hose following the vulcanization by welding its ends to a pressure medium source one above the operating pressure is exposed to lying pressure.

High pressure hoses of this type are available in various designs mainly used in hydraulics. The wire braiding can be multilayered Be trained, and in addition, textile braiding is sometimes used or a combination of textile and wire braids.

In terms of the method, it is known, for example, to pass the hose through to expand the air pressure only slightly and at the same time reduce the hose tension to push out; however, a structural change cannot be achieved in this way will.

According to another well-known suggestion, the hoses should be special be made volume-resistant by making them during the vulcanization process exposed to a pressure corresponding to the operating pressure, whereby the hose in the plastic State is widened so that the individual threads of the fabric are tightened and better dimensional stability is obtained. In this way it can be prevented that the tube collapses again after removing the core.

The structure is then pre-stressed and prevented after completion an impermissible expansion of the hose.

In all known methods of this type, however, the hose only exposed to a pressure which has a certain relationship to the operating pressure stands, d. That is, you want to ensure with some certainty that the hose the pressure to be applied later actually withstands. In practice, high pressure hoses are used at about 240 to 350 at. That way you get an average Service life of about 60,000 pressure pulses, which, however, is suitable for various areas of application is too little.

Now investigations have been carried out on burst hydraulic pressure hoses show that the hoses are consistently destroyed in those places where Gaps, openings or gaps existed between the wires of the wire mesh.

There the rubber lining of the hose was through the openings pushed out so far that a bubble formed in the shell that ruptured of the hose.

The invention is based on the object of a method for manufacturing of high-pressure hoses that have a multiple larger, especially 3- up to 10maul longer service life than those produced by the known processes Have hoses.

For this purpose, according to the invention, the hose is provided with a something The pressure below the rupture pressure of the hose is briefly preloaded and immediately afterwards fully relaxed again.

The rupture pressure of a hose is known to be many times over above the operating pressure. A preload pressure is therefore used here, which is disproportionately greater than the pressures previously used for such purposes. Due to this short-term, extraordinarily large pressure effect, however, the to Reinforcement of the hose structure serving wires in their mutual position and in their internal structure aligned so that by improving the molecular structure and the outer structure of the wire braiding is completely uniform Hose cover results and thereby the gaps are eliminated, which sometimes between individual Wires of the wire mesh exist. But this results in an increase in average service life to at least 180,000, often even to 600,000 pressure pulses, which means a considerable increase in service life.

The pre-stressing takes place at the same time as a test process, so that the process step according to the invention does not require any additional expenditure of time and costs required.

These and numerous other details of the procedure are emerging the following description of some exemplary embodiments. In the drawing are schematic cross-sections (on an enlarged scale) of typical hoses with one and two wire braids before and after the pre-stressing according to the invention illustrated. It shows F i g. 1 is a perspective view of a hydraulic Hose with a single wire braid, with the cut chosen in this way is that the (usual) hose structure can be seen, F i g. 2 is a view similar F i g. 1, which is a pre-claimed according to the method step according to the invention Figure 3 shows a perspective view of a piece of tubing (in cut-open view) with two wire braiding, FIG. 4 is a view similar to FIG. 3, which is a pre-claimed according to the method step according to the invention Hose section shows.

Fig. 1 shows a hydraulic hose with a single rubber-coated one Wire braiding.

The Schlich contains a seamless, oil and fat resistant one Tube 10 made of synthetic rubber, which is supported by a wire braiding 11 made of steel higher Firmness is surrounded. Above the wire braid 11 is a likewise tubular one Textile braiding 12 for anchoring and above a cover 13 made of synthetic Rubber is provided that is resistant to attack by oil and moisture and is subject to low wear.

In the manufacture of the hose shown in Fig. 1 takes place an elongated core used initially for forming the tube 10 from synthetic Rubber is used and which then runs through a wire braiding machine with the tube 10, in which the wire braiding 11 is applied to the tube 10. After the subsequent Applying the textile braid 12 and the outer cover 13 is the whole Vulcanized hose. It is understood that suitable at the ends of the hose Coupling pieces are provided.

The vulcanized manufactured in the manner described above Hose can be arranged on a holder and coupled to a pressure device will; then the structure of the tube is shaped by the For a brief moment a pressure of about 90% of its pressure Rupture pressure is exposed. For example, one with a single wire braid is made provided 1; 27 cm hose, d'el has a rupture pressure of about 1000 at, eiri "e" m exposed to instantaneous pressure of about 840 at.

This pre-stress changes the molecular structure of the steel wire changed as desired, and it will continue to be the individual wires in the Wire braiding is aligned and mutually displaced so that one is completely ideal braiding results, as shown in FIG. 2 is shown, in contrast to the rather irregular braiding according to FIG. 1.

In the hose according to FIG. 1, the wires run in the wire braiding 11 are very irregular, are sometimes obliquely directed and show mutual distances on. F i g. In contrast, 2 shows the piece of hose after carrying out the method according to the invention Pre-stress; the wires of the tubular braiding 11 are completely uniform here aligned and form a perfect flexible metallic protective covering that the individual wires lying next to one another have no free spaces between them set free.

In the F i g. 1 and 2 are the individual wires with the reference number 14 denotes; They are arranged in groups, with the number of wires per group is chosen very schematically in the drawing and not necessarily the actual one Number in a practical embodiment of a hose with wire braiding is equivalent to.

In the F i g. -3 and 4 is a hose with a double wire braiding illustrated. This hose contains a seamless one that is resistant to oil and grease Tube 16 made of synthetic rubber, over which a first tubular wire braid 17 made of high strength wire is provided, above a tubular, rubber-like Insulation layer 18, furthermore a second tubular wire braid 19, over it a tubular textile braid 20 and an outer cover 21, which consists of a Resistant to oil and moisture, very low-wear synthetic Rubber is made.

From Fig. 3 it can be seen that the tubular Umfiechtungen 17 and 19 are formed by individual wires 22 and 23, respectively; the free spaces between the individual wires as well as the existing oblique alignment of the individual Wires and the groups of wires are shown in FIG. 3 again a bit exaggerated illustrated.

From Fig. 4 it can be seen that the wires 22 and 23 of the Umfiechtungen 17, 19 after carrying out the pre-stressing of the hose according to the invention in ideal mutual alignment, with both the individual wires as also neighboring wire groups are in close mutual contact and no gaps let free between you.

The tube 16 and the tubular insulation layer 18 are on this On the outside completely and without gaps thanks to the even wire braiding l7, 19 enclosed, so that a highly flexible, provided with a wire reinforcement hydraulic hose results in an extremely long service life can be exposed to abnormally high pressures.

Claims (1)

Claim: Process for the production of a high pressure hose, consisting of a tube made of synthetic rubber, one placed on the tube tubular braid made of high strength steel wire and a tubular braid Coating made of synthetic rubber with the vulcanized hose in the connection at vulcanization by connecting its ends to a pressure medium source is exposed to a pressure above the operating pressure, characterized in that, that the hose with a slightly below the rupture pressure of the hose Press briefly is pretensioned early and then fully relaxed again immediately afterwards. Considered publications: German Patent Specifications No. 712 606, 767 339; U.S. Patent No. 2974713.