JPH0258518B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a low-pressure reinforced rubber hose in which the reinforcing layer between the inner and outer layers is formed by coarsely braiding reinforcing threads made of twisted nylon filament threads. It is applied to automobile radiator hoses, heater hoses, etc.

In this specification, the unit of twist number "t/m" refers to the number of twists of yarn per meter of yarn length.

<Prior Art> Conventionally, this type of low-pressure reinforced rubber hose has typically used nylon filament yarn twisted together at a twist rate of about 150 t/m as the reinforcing yarn.

<Problems to be Solved by the Invention> However, it has been found that this low-pressure reinforced rubber hose has the following problems.

In other words, during the manufacturing stage, when a mandrel is inserted into the molded hose and vulcanization is performed (at around 150°C), the reinforcing threads bite into the inner layer due to heat shrinkage, producing a low-pressure reinforced rubber hose with a thin inner layer. easy to be When using a low-pressure reinforced rubber hose with a thin inner layer, intermittent pressurization can cause the friction between the reinforcing thread and the inner rubber to cause the rubber to break, making it more likely that the hose will break or leak quickly. . Especially for items that are vulcanized in a bent state, such as radiator hoses, the outside R
Since the reinforcing yarn in the section is stretched, it bites into the inner layer side significantly, and there is a large difference in the biting into the inner layer side at the inner R section, making it more likely that product defects will occur.

<Means for Solving the Problems> An object of the present invention is to provide a low-pressure reinforced rubber hose that can solve the above problems and improve yield and service life.

Therefore, in the low-pressure reinforced rubber hose of the present invention, the reinforcing layer between the inner and outer layers is formed by coarsely braiding reinforcing threads made of twisted nylon filament threads, in which the reinforcing threads are Number of twists of nylon filament yarn: 90t/
It is characterized in that it is made by twisting each other with a length of less than m.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a radiator hose according to one embodiment.

In FIG. 1, a hose 1 has an inner layer 2 and an outer layer 3.
The reinforcing layer 4 is formed by coarsely braiding the reinforcing yarn Y between the two.

The inner layer 2 and the outer layer 3 are each extruded from a rubber material such as CR or EPDM.

The reinforcing yarn Y is made by twisting nylon filament yarns with a twist number of 90t/m or less. This nylon material is 6,6-nylon, which has good heat resistance.
- Either nylon may be used. Note that nylon spun yarn has a large tensile elongation and is not suitable for reinforcing yarn.

"Roughly braided" means that the distance l between the reinforcing threads is several times larger than the diameter of the reinforcing threads Y, and in the case of a radiator hose, the number of braids is 32.

According to this radiator hose, the amount of penetration of the reinforcing yarn Y into the inner layer 2 is as compared to when the reinforcing yarn is a nylon filament yarn with a twist count of 150 t/m.
It was found that the size was sufficiently small and that the above-mentioned problems were unlikely to occur.

Figure 2 is a graph showing the basis for such an effect.Nylon threads of various twist numbers (1260D/2, 150℃ moist heat set) are placed on top of an extruded inner layer (EPDM) with a wall thickness of 2.2mm. ) was braided (32 strokes) and the outer layer (EPDM) was extruded with a wall thickness of 1.0 mm. After vulcanization at 150°C for 30 minutes, the inner layer thickness was measured after being left for 24 hours. The average value (n =
6).

As shown in Figure 2, the inner layer thickness of a hose using nylon filament yarn with a twist number of 90 t/m or less is about 1.35 mm or more, and the inner layer thickness of a hose with a twist number of 150 t/m is about 1.0 mm. It's big in comparison.

Furthermore, the effect of preventing the decrease in inner layer thickness is as follows:
I think this is because the smaller the number of twists, the flatter the cross section of the nylon thread becomes, which prevents it from digging into the inner layer 2.

<Operations and Effects of the Invention> As described above, in this invention, a reinforcing yarn is constructed by twisting nylon filament yarns at a twist rate of 90 t/m or less, and thus a low-pressure reinforced rubber hose with a desired thick inner layer can be manufactured. As a result, the service life can be extended, and the yield can be improved.

In particular, even for items such as radiator hoses that are vulcanized in a bent state, there is no large difference in the amount of penetration into the inner tube rubber layer between the outer R and inner R.
The above effect becomes noticeable.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a radiator hose according to an embodiment of the present invention, and FIG. 2 is a graph showing the state of penetration of nylon threads with different numbers of twists into the inner layer after vulcanization. 1...Reinforced rubber hose for low pressure, 2...Inner layer, 3
...Outer layer, 4...Reinforcement layer, Y...Reinforcement thread.

Claims (1)

[Scope of Claims] 1. A low-pressure reinforced rubber hose in which the reinforcing layer between the inner and outer layers is formed by roughly braiding reinforcing threads made by twisting nylon filament threads, wherein the reinforcing threads are made by twisting the nylon filament threads together. A reinforced rubber hose for low pressure use, characterized by being made of strands of several 90t/m or less.