JPS6249863B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application relates to a method of manufacturing a rubber hose having a flat cross-sectional shape.

Conventional methods for manufacturing rubber hoses with flat cross sections include forming the hose into a flat cross-sectional shape from the beginning and vulcanizing it, or molding it into a circular cross-section using a circular core metal, then removing the core metal and leaving the unvulcanized material. A method is known in which a sulfurized hose is flattened and then heated and vulcanized.

However, with the method of forming the material flat from the beginning, when the inner rubber layer, the fiber reinforcement layer, and the cover rubber layer are sequentially laminated, air tends to remain between each layer, and each unvulcanized material is Since it is necessary to bend the hose several times, the material at the bend is subject to tension, which tends to make the thickness of the material and the spacing between the threads of the fiber reinforcement material uneven, which tends to cause variations in the durability of the hose. Ta. On the other hand, in the case of a method in which a core metal is used to form a cylinder into a cylindrical shape, the core metal is removed, flattened, and heat vulcanized, a uniform state is obtained at the molding stage, but it is still an uncured state. Therefore, even if the shape is formed with a uniform cut angle, the degree of stress applied to the bent part and the flat part is different when flattening.
The difficulty that the thickness of the rubber of each layer at the folded end and the spacing between the fibers tend to be uneven was unavoidable. Moreover, not only in the method of forming into a flat state, but also in the method of forming into a cylindrical shape and then flattening it, the rubber and fibers at the bent end are heated while being locally stretched, so they shrink due to heat during vulcanization. There is also a drawback that the dimensional accuracy after vulcanization is deteriorated because the elasticity is larger than that of the rubber or fiber in the flat part in a non-stretched state, and an improvement has been desired.

The present application provides a method for manufacturing a flat hose that does not have such drawbacks. That is, by first forming it into a cylindrical shape and performing primary vulcanization while it remains circular, the reinforcing fibers are adhesively fixed and the dimensional accuracy of each part is maintained, and then the ends are sealed and vacuum suction is applied from one end. By flattening the hose and performing secondary vulcanization while maintaining the flat state, not only can the desired dimensional accuracy be obtained with good reproducibility, but also local disturbance of the reinforcing fiber layer will not occur. It has been discovered that a product of extremely stable quality can be obtained not only in terms of appearance but also in terms of durability.

As the inner rubber and cover rubber used in this application, all known natural rubbers and synthetic rubbers can be used alone or in a blend. Any other known rubber compounding agents such as vulcanizing agents, vulcanization accelerators, anti-aging agents, fillers, etc. can also be used.

The fiber reinforcing material is also not particularly limited, and in addition to natural fibers and synthetic fibers, fibrous metals and inorganic fibers can be used alone or in combination as appropriate. There are no restrictions on the texture of the fiber reinforcing material, and it can be used in the form of a woven or knitted fabric, for example, but a sudare weave is particularly suitable. Although these fiber reinforcing materials can be used as they are in the form of cloth, it is preferable to use materials that have been previously treated with a resin or rubberized in order to enhance the reinforcing effect.

The woven fabric and core metal used in this application can be any of those commonly used in the manufacture of hoses and the like. Further, there is no need for a special pressure reducing device to be used for flattening the hose; all that is required is a pressurizing jig, a vacuum pump, and a conduit for sealing the end edge of the hose. Another method for flattening a cylindrical hose that has undergone primary vulcanization is to apply pressure to the entire length of the hose using a press. The cylindrical hose that has been molded will return to its cylindrical shape when the pressure is removed, so you can either use a steam press and heat and vulcanize under pressure, or press the entire length of the hose together with an iron plate to create a flat shape. It is difficult to flatten a long hose all at once, as it is necessary to fix it with bolts or other means that maintain the Due to its drawbacks, the vacuum suction method is preferred.

The manufacturing method of the present invention will be specifically described in detail with reference to Examples below.

Example The rubber composition shown in Table 1 was kneaded on a roll,
The inner rubber layer was distributed to a thickness of 5 mm, and the cover rubber layer was distributed to a thickness of 2 mm.

As a reinforcing material, a treated cloth was used in which a polyester cord for tires with a diameter of 0.9 mm was woven in a sudare weave at a density of 10 cords per 1 cm, and the treated cloth was topped with the compounded rubber shown in Table 1 to a thickness of 1 mm.

As the first step, a layer of 5 mm thick inner rubber is wrapped around a core metal with a diameter of 203.2 mm and a length of 10 m, and then the inner rubber is wrapped in a layer of 5 mm thick. ) 17 Zinc white (Sakai Chemical No. 3) 1.5 Stearic acid 1.0 Paraffin 0.6 Carbon black (SAF) 34.0 Process oil (Kyodo Oil Sonic Process
-50) 7.5 Accelerator (MSA manufactured by Ouchi Shinko Chemical Co., Ltd.) 0.6 Sulfur 0.8 A layer of reinforcing cloth was wrapped around the reinforcing cloth at an angle of 54.5 degrees to the core shaft. Further, on top of that, wind the warp threads of the second layer reinforcing cloth so that they intersect with the warp threads of the first layer reinforcing cloth and make an angle of 54.5 degrees with respect to the axis of the core bar. Layered. A 2 mm thick cover rubber was wrapped on top of this to form a cylindrical hose.

Next, in the second step, the outer circumferential surface of the unvulcanized hose molded on the core metal is uniformly wrapped with nylon plain weave cloth, and then wrapped in a vulcanizing can at 145℃ for 60 minutes.
The primary vulcanization was carried out for 1 minute.

After the first vulcanization, in the third step, the nylon fastening cloth is loosened, the core metal is removed, and the outer diameter is 221.2 mm and the inner diameter is 221.2 mm.
A hose with a substantially circular cross section of 203.2 mm was obtained. One end of this hose is 9mm thick, 45mm wide, and 450mm long.
Bolt holes were drilled at both ends of the two iron plates in the longitudinal direction, and bolts were tightened between the two iron plates to fix the end of the hose in a flat shape. The other parts of the hose were made flat in the same way, but with an inner diameter of 6.5
A forked metal conduit with an outer diameter of 10.5 mm was inserted until the two ends of the pipe were almost in contact with the end of the tightening iron plate. The other end of this metal conduit is a three-pronged tubular body.
It was assembled into a main conduit and connected to a vacuum pump with a pressure-resistant rubber hose. This vacuum pump was operated to perform reduced pressure suction until -600 mmHg was indicated. As a result, all the air inside the 10 m long hose was suctioned out and flattened. After all parts of the hose were flattened, the end of the conduit was pulled out by using another set of iron plates to double the tightening part so that the degree of depressurization at the cut angle would not decrease even if the conduit was pulled out.

The hose, which has been kept flat in this way, is placed in the fourth
As a process, put it back into the vulcanization can and heat it at 145℃ for 60 minutes.
Next vulcanization was performed. The hose that has completed secondary vulcanization is
The hose now has a flat shape that does not return to its cylindrical shape even after removing the fastener and returning the pressure inside the hose to normal pressure.

When the hose obtained by the method of the present application was disassembled, the thread spacing of the reinforcing fabric at the bent part remained uniform as in the flat part, and the thickness of the inner rubber layer and cover rubber layer was almost the same as that at the bent part and the flat part. No differences were observed between the two groups.

According to the method of the present application, even large diameter and flat hoses, which have traditionally been difficult to manufacture due to dimensional accuracy, can be manufactured without any problems, and even long hoses can be easily manufactured without using special equipment. It can be said that this technology is extremely useful industrially.

Claims (1)

[Claims] 1. A first step of forming an unvulcanized cylindrical rubber hose by sequentially winding an inner rubber layer, a fiber reinforcing layer material, and a cover rubber layer around a core metal, and wrapping a tightening cloth around the outer periphery of the unvulcanized molded hose. The second step is heated and vulcanized.
The third step is to flatten the hose by sealing one end of the hose and suctioning it under reduced pressure from the other end after removing the tightening fabric and core metal, and A method for manufacturing a flat hose, comprising a fourth step of performing heat vulcanization again.