JPS61127335A - Manufacture of high-pressure hose - Google Patents

Abstract

PURPOSE:To enable to shift to the next process by keeping a cured state as it is after braiding and wrapping of a reinforcing layer, by a method wherein an inner rubber layer is made to cure by vulcanizing into a semivulcanized state by radiating electron rays to the surface of the inner rubber layer molded in a tubular state by extruding onto a mandrel. CONSTITUTION:An inner rubber layer 12 is formed by putting unvulcanized nitrile-butadiene rubber (NBR) extruded through an extruding machine 22 over a mandrel to be sent out through an unwinder 20, and the mandrel-filled inner rubber layer 12 is wound up on a wind-up machine 40 through an electron ray radiating device 30. A surface layer of the inner rubber layer 12 is made into a semivulcanized state up to a predetermined depth by a method wherein a running rate of the inner rubber layer 12 is set up at a constant rate and accelerating voltage and a current value of electronic rays are selected appropriately. When the layer is turned into the semivulcanized state, resisting force against outside force is increased by improving green strength. Then even if a metallic wire and fibrous code of a reinforcing layer are either braided or wrapped, deformations such as swelling of the outer diameter and extension in a lengthwise direction are not generated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a high-pressure hose, and in particular, the surface of an inner rubber layer containing a mandrel is irradiated with an electron beam to vulcanize it to a semi-vulcanized state. In this way, the reinforcing layer is knitted and wrapped to prevent deformation caused by the expansion of the outer diameter of the inner rubber layer.

[Conventional technology]

Conventionally, when manufacturing high-pressure hoses, unvulcanized rubber extruded from an extruder is placed on a mandrel to form the inner rubber layer, and metal wire such as steel wire or fiber cord is braided or wound on top of the mandrel. After that, an outer rubber layer is coated on top of that and molded, and the surface is vulcanized with lead covered. After vulcanization, the lead is peeled off and the mandrel is extracted, and the finished product is made. It is said that Sometimes the reinforcing layer is braided or wrapped with metal wire, etc.
In order to provide the necessary pressure resistance for a high-pressure hose, the inner rubber layer is tightened with a tension of several kg to 20 kg per hose, but since the inner rubber layer is unvulcanized rubber,
If tension is applied with a metal wire, etc., the inner rubber layer will be squeezed and the outer diameter behind the reinforcing layer will bulge.If the entire length is squeezed in this state, the inner rubber layer will be stretched and the outer diameter will expand backwards. After the sagging, knitting or wrapping of the reinforcing layer is completed, the inner rubber layer is deformed to a non-uniform thickness, which significantly impairs the performance of the product.

FIG. 5 shows a state in which the inner rubber layer is squeezed, and in the same figure, reference numeral 10 is a mandrel, 12 is an inner rubber layer, and 14 is a mandrel.
15 is a braided reinforcing layer, 15 is a metal wire or fiber cord, and 13 is a bulge of the inner rubber layer.

As a means to prevent such deformation of the inner rubber layer, conventionally the inner rubber layer extruded onto a mandrel is pulled out and placed in a liquid before being fed into a reinforcing layer knitting machine or winding machine. Measures are taken to harden the material by spraying it with a cooling medium such as nitrogen (-195° C.).

[Problem that the invention seeks to solve]

The method of curing rubber using a cooling medium lowers the surface temperature of the inner rubber layer to about 150 degrees Celsius, so if you leave it as it is after knitting and wrapping the reinforcing layer, the temperature will deteriorate over a considerable period of time. The temperature will remain below 0°C for some time.

For this reason, moisture in the air condenses on the surface of the reinforcing layer, rusting occurs on the steel wire reinforcing layer, and water adheres to the inside of the fiber reinforcing layer. Vulcanization may cause serious defects in product performance and quality. Therefore, generally, after knitting and wrapping the reinforcing layer, hot air is blown to dry the attached moisture. However, this method of using hot air requires a large amount of electricity and steam as a hot air generation source.
Since it takes a considerable amount of time for the inner rubber layer to return to room temperature, there is a problem in that energy consumption increases.

In addition, the cooling medium needs to be supplied to the cooling cylinder through piping with a cold cover, which not only increases the equipment cost of the piping system (in order to maintain the inside of the cooling cylinder at an extremely low temperature, Since it is necessary to supply a large amount of cooling medium, there is a problem in that a large amount of cost is wasted.

Furthermore, the work involved in spraying the cooling medium onto the inner rubber layer has a high risk of frostbite due to contact with the equipment of the apparatus, and there are also problems in terms of ensuring work safety.

This invention solves the above problems, saves energy and costs when reinforcing the inner rubber layer containing a mandrel, cures it by a highly safe process, and braids and wraps the reinforcing layer in a cured state afterward. An object of the present invention is to provide a method for manufacturing a high-pressure hose that can be transferred to the next process while maintaining the same.

[Means for solving problems]

The surface of the inner rubber layer, which is extruded onto a mandrel and formed into a tube shape, is irradiated with an electron beam, and after the inner rubber layer is cured and cured to a semi-vulcanized state, the reinforcing layer is knitted or wrapped. Do the following.

[Effect]

When the unvulcanized rubber of the inner rubber layer is irradiated with electron beams and vulcanized to a semi-vulcanized state, it hardens and increases the green strength of the rubber. When attached and tightened with metal wires or fiber cords, even when subjected to force, the outer diameter of the inner rubber layer does not bulge or sag due to elongation, and the reinforcing layer maintains a uniform thickness. Can be knitted or wrapped.

〔Example〕

FIG. 1 shows an embodiment of the manufacturing method according to the present invention, in which unvulcanized nitrile butadiene rubber (NBR) extruded from an extruder 22 is placed on a mandrel 10 fed out from an unwinder 20. cover to form the inner rubber layer 12,
This inner rubber layer 12 containing the mandrel is passed through a free roller 16 disposed in an electron beam irradiation device 30, and then passed through a winding machine 4.
Wind it to 0.

The electron beam irradiation device 30 forms a closed chamber 32 in which parts other than passages 33 and 34 of the inner rubber layer 12 provided on the exit side and the inlet side are sealed, and a scanning tube 35 and an acceleration tube 36 are provided in the center.
This is the provision. A high frequency power source 38 is connected to the acceleration tube 36 via a DC high voltage generator 37, and an operation 1139 is connected to the DC high voltage generator 37 and the high frequency power source 38. In addition, the scanning tube 3 of the electron beam irradiation device 30
A pair of free rollers 17, 18 provided with a plurality of grooves are disposed on both sides below the roller 5, as shown in FIG.

The inner rubber layer 12 is reciprocated in the groove between one and the other of the free rollers 17 and 18 one after another in a sash-like manner. The entire circumference of the inner rubber layer 12 in cross section is irradiated with the electron beam emitted from the scanning tube 35.

Generally, when unvulcanized rubber is irradiated with an electron beam, its surface layer is vulcanized and hardened due to the transmission characteristics of the electron beam, but the depth of vulcanization and degree of vulcanization are determined by the accelerating voltage. and can be changed by the current value. The electron beam transmission characteristics for a substance with a specific gravity of 1 are shown in Figure 3.-0 Therefore, the running speed of the inner rubber layer 12 is set to a constant speed, and the accelerating voltage and current value of the electron beam are appropriately selected. By controlling the irradiation dose by
The surface layer of No. 2 can be vulcanized to a predetermined depth into a semi-vulcanized state. The irradiation dose of the electron beam is controlled by an operation panel 39.

When the inner rubber layer 12 is vulcanized to a semi-vulcanized state in this way, the surface layer is hardened and the green strength is improved. 100% modulus corresponding to the electron beam irradiation dose and 30
When the degree of improvement in 0% modulus is expressed as an index with the non-irradiation time being 100, it becomes as shown in Fig. 4. In general, the practical irradiation dose of electron beams for rubber is around 10 Mrad (5 to 12
Mrad), the 100% modulus in this case will be improved by 5 times, and the 300% modulus will be improved by more than 10 times.

In this way, the surface of the inner rubber layer 120 becomes semi-vulcanized, improving green strength and increasing resistance to external forces. Therefore, even if the metal wire or fiber cord of the reinforcing layer is knitted or wrapped around the inner rubber layer 12, the resistance to tightening force is large, so the outer diameter may bulge or the fiber cord may expand in the length direction. No significant deformation occurs.

The electron beam irradiation to the inner rubber layer 12 may be carried out between the extruder 22 and the winder 40 as in the embodiment shown in FIG. After winding up on the winder, the inner rubber layer may be pulled out from the winder again and irradiated.

〔Effect of the invention〕

As explained above, according to the present invention, since the unvulcanized inner rubber layer extruded onto the mandrel is vulcanized and hardened to a semi-vulcanized state, the reinforcing layer is knitted,
Alternatively, after wrapping, the outer rubber layer can be coated as is, eliminating the need for drying by blowing hot air as in the conventional cooling and curing method, and reducing the energy consumed as a heat source. You can save money.

Further, according to the present invention, since the amount of power required for electron beam irradiation for curing the inner rubber layer is extremely small, the inner rubber layer can be cured at a lower cost than when using a conventional cooling medium.

Further, according to the present invention, in the vulcanization process after coating the outer rubber layer, the inner rubber layer, which is already in a semi-vulcanized state, is vulcanized, so the time required for vulcanization is longer. It can be significantly shortened.

Furthermore, according to this invention, the safety in the curing process of the inner rubber layer can be made higher than in the case of using a conventional cooling medium, and combined with the fact that the process after curing is a tube path, both performance and quality are improved. It is possible to produce an excellent high pressure hose at a low cost.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the present invention, Fig. 2 is a perspective view showing the electron beam irradiation state, Fig. 3 is a transmission characteristic diagram of the electron beam, and Fig. 4 is a graph showing the relationship between the electron irradiation dose and the modulus. A diagram showing the relationship, FIG. 5 is a side view showing the bulging state of the inner rubber layer. In the figure, 10 is a mandrel, I2 is an inner rubber layer, and 30 is an electron beam irradiation device.

Claims (1)

[Claims] A method of manufacturing high-pressure hoses by knitting or wrapping a reinforcing layer made of metal wire or fiber cord on an inner rubber layer and then covering the reinforcing layer with an outer rubber layer. The surface of the unvulcanized inner rubber layer molded into the rubber layer is irradiated with an electron beam, the inner rubber layer is cured to a semi-vulcanized state, and then the reinforcing layer is knitted or wrapped. A method for manufacturing high pressure hoses.