JPH0146753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fiber-reinforced hose, and in particular to a rubber hose with a jacket reinforced with a fiber-reinforced layer, due to the manufacturing process, unevenness in inner diameter and the problem with the jacket, which have conventionally been unavoidable. This article discloses the results of development aimed at eliminating surface irregularities.

Conventional rubber hoses of this kind are made by extruding an inner tube as the inner rubber, and after cooling it, it is generally reinforced with braid or spiral reinforcement using a fiber material such as polyester or vinylon, and then an outer cover is layered on top of it as the outer rubber. The fibrous reinforcing layer was extruded and then passed through a hot air chamber or other vulcanization tank, during which time the entire body was continuously vulcanized, but due to the dehydration of the fibrous reinforcing layer immediately after it was formed. Furthermore, due to the heating for vulcanization mentioned above, the softening flow of the rubber and the thermal contraction of the fiber material occur simultaneously, so the inner tube is squeezed unevenly and it is difficult to finish it with a uniform inner diameter. The outer surface of the cover has a tendency to have surface irregularities corresponding to the knitting or winding pattern of the fibrous reinforcing layer, spoiling the appearance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a fiber-reinforced hose that advantageously solves these difficulties.

The present invention provides that the inner tube is previously subjected to a hardening treatment that causes hardening, or at least semi-hardening, in order to prevent thermal shrinkage of the fibrous reinforcing layer resulting from the heating operation required when making the hose. Before applying the fibrous reinforcing layer to the inner tube, which has been previously subjected to such hardening treatment, a thin intermediate layer having a thickness sufficient to absorb the above-mentioned heat shrinkage is formed on the inner tube. This is based on the knowledge that the effects of heat shrinkage on the fibrous reinforcing layer can be prevented.

This invention involves the steps of extrusion molding an inner tube and subjecting it to a single hardening process, forming a thin intermediate layer with a thickness of 0.3 to 1.0 mm around the outer periphery of the hardened inner tube, and surrounding the thin intermediate layer. A fibrous reinforcing layer is formed on the fibrous reinforcing layer, followed by heating, and the resulting shrinkage embeds the fibrous reinforcing layer under the surface of the thin intermediate layer, and then an outer cover is formed on the fibrous reinforcing layer. This is a manufacturing method for a fiber-reinforced hose characterized by curing.

Suitable materials for the thin intermediate layer include unvulcanized rubber and thermoplastic synthetic resin, which are convenient for extrusion molding over the outer periphery of the hardened inner tube.

This thin intermediate layer needs to be thick enough to cause it to be buried under the surface of the thin intermediate layer due to thermal shrinkage when the reinforcing layer is heated for dehydration after the fibrous reinforcing layer is formed. do.

On the other hand, since it is rather common to use rubber materials for both the inner tube and outer cover of this type of hose, their curing operation or treatment is usually carried out by ordinary heat vulcanization.

The advantageous application of the present invention to such a rubber hose will be explained below with reference to specific embodiments.

An example of a line suitable for continuously manufacturing fiber-reinforced hoses according to the present invention is shown in FIG. 1, and cross sections of half-finished products and finished hoses at two locations along the line are shown in FIGS. 2a, b, and c. The steps are shown in order, and the cross section of a conventional hose of this type is shown in a slightly exaggerated manner for comparison in FIG.

In Fig. 1, 1 is an extruder for the inner tube 2, and if necessary, the extruder for the inner tube 2 is used to maintain the extruded form of the inner tube until it is cured in the vulcanization tank 3 and throughout the subsequent steps. Therefore, a pressurized source of the filling fluid is provided.

The inner tube passed through the vulcanization tank 3 and vulcanized is represented by 4, and is further introduced into, for example, an extruder 5, where a thin intermediate layer 6 of unvulcanized rubber or thermoplastic synthetic resin is formed into an inner tube. It is formed around the tube 4.

This thin intermediate layer 6 can be appropriately selected from a range of 0.3 to 1.0 mm for a normal hose size, for example, an inner diameter of about 5 mm to 50 mm, depending on the material of the fibrous reinforcing layer 8 to be applied next.

That is, the thin intermediate layer 6 is passed through the reinforcing layer forming machine 7.
A braid or spiral fiber reinforcing layer 8 made of a fiber material such as polyester or vinylon is placed on the outer surface of the fiber, and the fiber is directly introduced into a heating tank 9 to remove moisture contained in the fiber.

At this time, the fibrous reinforcing layer 8 undergoes heat shrinkage depending on the characteristics of the fibrous material, but in this invention, this effect is no longer transmitted to the inner tube, so its form does not collapse and the inner diameter is adjusted to the extrusion dimension. It is maintained at a constant value according to the conditions. At this time, the fibrous reinforcing layer 8 is buried under the surface of the thin intermediate layer 6, so as shown in FIG. 2b, the outer surface of the thin intermediate layer 6 is smoothed, and the outer cover is Helps prepare the underlying surface.

Generally, if the thickness of the thin intermediate layer is less than 0.3 mm, the fibrous reinforcing layer 8 will not be buried sufficiently under the surface, and the surface of the base covering the outer cover will become extremely uneven; If the inner tube gauge is made thicker, the inner tube gauge becomes relatively thinner, which poses a problem in molding.

Subsequently, the outer cover 11 is passed through an outer cover rubber extruder 10 to extrude the outer cover 11 overlapping the thin intermediate layer 6 with the fibrous reinforcing layer 8 buried under the back surface, and then introduced into the overall vulcanization tank 12. The product hose thus vulcanized is wound onto the reel 14.

As shown in FIG. 2c, the cross section of the product hose thus obtained is smooth and free of any irregularities on both the inner and outer surfaces.

The entire vulcanization tank 12 may be of any known type that is conveniently used for continuous vulcanization treatment, but in the example shown in FIG. The case is shown in which the tank is filled with a heated fluid under pressure until the tank is discharged.

As described above, the heat shrinkage of the fibrous reinforcing layer causes unevenness on the inner and outer surfaces of the product hose, as shown in Figure 3, which was a problem in terms of securing a predetermined inner diameter and external shape, but this is an advantage. It is clear that it can be solved as follows.

Thus, according to the present invention, it is possible to easily produce a high-quality hose that has a uniform inner diameter, has no surface irregularities on both the inner and outer peripheries, has excellent appearance properties, and has no variation in quality.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a hose production line, FIGS. 2a, b, and c are sectional views of a two-stage semi-finished product and a finished hose, and FIG. 3 is a sectional view of a conventional hose. 4...Inner tube, 6...Thin middle layer,
8...Fibrous reinforcement layer, 11...Outer cover.

Claims (1)

[Claims] 1. A step of extruding the inner tube and subjecting it to a single hardening treatment, and forming a thickness of 0.3 on the outer periphery of the hardened inner tube.
A step of forming a thin intermediate layer of ~1.0 mm, forming a fibrous reinforcing layer around this thin intermediate layer, heating it, and shrinking the fibrous reinforcing layer under the surface of the thin intermediate layer. A method for manufacturing a fiber-reinforced hose, which is characterized in that after passing through a step of burying the hose, an outer cover is further formed on the hose, and then the entire hose is hardened.