JPS5878738A - Manufacture of curved pipe made of rubber - Google Patents

Abstract

PURPOSE:To arrange metal wires uniformly without requiring any skill and to obtain the titled pipe being excellent in appearance and quality, by providing an elastic fiber reinforcement layer, by winding the metal wires on a straight-pipe mandrel, by making an external rubber layer have a specified thickness, and by curving the pipe by means of a curved-pipe mandrel. CONSTITUTION:An internal rubber layer 2, a reinforcing cloth layer 3, a metal reinforcement layer 4 and an external rubber layer 5 are wound in this sequence on a straight-pipe mandrel 1. On the occasion, an elastic fabric or a net-shaped material is used as the reinforcing cloth, and metal wires are wound spirally on the reinforcing cloth layer 3 within the range of 1/2-1/10 of a straight-pipe- shaped hollow molded body. In addition, a rubber material 7 in the same kind of the external rubber layer is stuck, so as to cover about 1/3 of the outer peripheral surface, on the external rubber layer which constitutes the outer peripheral side when a curved pipe is formed. Then, curve forming is applied by means of a curved-pipe mandrel. In this way, uniform arrangement of metal wires can be obtained without any skill, and the appearance and qualtity of the pipe is made excellent, because the thickness of the external rubber layer on the outer peripheral side is made large.

Description

[Detailed Description of the Invention] This invention can increase or decrease the contents of a tank made of FRP,
When connected to a container that is easily subject to displacement due to vibrations, such as a vehicle, it can easily follow the displacement of the container body.
The present invention also relates to a method of manufacturing a bent rubber tube that has low reaction force and high pressure resistance.

In Japan, the Building Standards Act prohibits aquariums installed on the rooftops or basements of pill buildings from being installed directly on the floor, and requires them to be installed on a pedestal. In the case of FRP aquariums, the degree of flexure of the aquarium differs when the water is full and when the water is low, so the rubber bent pipe used when connected to the aquarium body can easily follow the pinch of the aquarium body and will not buckle even when the pressure is reduced. To prevent problems such as flattening without buckling, methods such as increasing the hardness of the rubber and increasing the number of briars in the reinforcing fabric layer, or using a metal wire like steel wire as a reinforcing material are taken. It's here. However, in such a method, the reaction force of the bent pipe mouth body becomes large and unnecessary stress is applied to the FRP aquarium, which may reduce the durability of the P'RP aquarium and also cause damage to the aquarium body. The disadvantage was that it was difficult for the rubber bent pipe to follow the displacement.

On the other hand, if the rubber hardness is lowered and the number of plies of the reinforcing fabric layer is reduced, this problem will not occur, but the bent pipe will be more likely to buckle or deform, causing an increase in flow resistance.

As a means to improve these problems, it is known to lower the rubber hardness appropriately and use reinforcing cloth and metal wire together, but it is difficult to uniformly wrap these reinforcing materials on a bent pipe mandrel. This requires considerable skill, and even for those skilled in the art, there is still a problem of lack of uniformity, which causes abnormal deformation when pressurized.

The present application was made with the aim of solving such problems, and uses a method of winding a metal wire on a straight pipe mandrel and then bending it with a curved pipe mandrel, so no skill is required. A uniform arrangement of metal wires can always be obtained, and therefore, it has excellent deformation resistance during pressurization or decompression, and by providing a fiber reinforced layer with elasticity, it can be achieved as a forming method with excellent bending workability. It is something that The method of extruding a straight tubular hollow body and inserting the core into a curved mandrel is known from Mineshoko No. 55-93441, and in this case, a highly rigid reinforcing material such as a wire is also used. However, with such extrusion/molding methods, it is impossible to provide a reinforcing fabric layer with elasticity, and it is impossible to provide a reinforcing fabric layer that has elasticity during bending without changing the thickness of the outer rubber layer on the outer peripheral side. When bending is performed, if a highly rigid material such as a wire is included, the wire will move during the bending process, creating an uneven appearance that will significantly impair the quality of the appearance and reduce durability. At negative pressure, only unusable products are obtained.

The present invention provides a reinforcing cloth layer having elasticity in a position close to the metal wire reinforcing material, and when bending and forming, the thickness of the outer rubber layer on the outer peripheral side is set to be lower than the thickness of the outer rubber layer on the inner peripheral side. Since the metal wire is also thick, the movement of the metal wire on the inner circumferential side during bending is restricted by the elastic reinforcing fabric layer.
At least the uneven movement due to the difference in curvature and the accompanying pitch fluctuation can be made uniform, and this also limits the movement of the metal wire on the outer peripheral side, so that the movement can be limited to a small amount. As mentioned above, for this slight movement,
By increasing the thickness of the outer rubber layer on the outer periphery side, problems with appearance quality can be prevented, and extremely uniform products can be easily obtained with almost no skill required.

As the rubber material used in this application, all known natural or synthetic rubbers can be used, and these may be used alone or in combination, but the rubber hardness when vulcanized is JIS
It is desirable that the A hardness is 30 to 70°.

In addition, the reinforcing fabric with elasticity used in this application includes:
It is desirable that the elongation rate in at least one direction is 1 inch or more. This is because if the elongation is small, bending becomes difficult.

However, if the elongation becomes too large, the reinforcing effect will be poor, so it is better to avoid this.

The selection criteria for this elongation rate differs depending on the curvature and diameter of the bent pipe, so it is necessary to select the optimum elongation rate in consideration of the shape, dimensions, and required performance of the product. The reinforcing fabric may be made of natural fibers, synthetic fibers, or inorganic fibers, or may be woven or knitted fabrics, as long as it has elasticity. According to the results of various experiments conducted by the present inventors, relatively coarse cloth materials such as sudare weave or mesh-like cloth are suitable. Leave the reinforcing cloth as is.
It can also be used, but the material must be made of the same material as the inner and outer layer rubber, or
Adhesiveness can be further improved by treating with a rubber or resin with good compatibility.

The metal wire reinforcing material used in this application is iron or alloy wire,
A wide range of wire rods can be used depending on the diameter of the product, desired pressure resistance, etc., but it is usually desirable to use wire rods in the range of α5 to 3-φ. When using iron wire, soft nails that are not hardened are preferable because they are easier to work with. Furthermore, the metal wire may be subjected to a pretreatment to improve its adhesion to rubber.

The metal wire winding pinch is the diameter of the straight hollow molded body.

It is necessary to wind the wire preferably in the range of 1/4 to 1/7. This is because if the pitch is too coarse, the reinforcing effect will be poor, and if the pitch is too thin, the bending workability will be inhibited.

The present invention will be explained based on specific examples.

Example 1 5 parts of Zinc White No. 3, 1 part of stearic acid,
As an anti-aging agent, N-phenyl N-Infropyl P-phenylenediamine (Robo 3C) + parts, naphthenic oil 15 parts 1, HAF carbon fiber.

Rubber dough mixed and kneaded in a ratio of 50 parts of rack, 10 parts of white gloss, 2 parts of sulfur, and 1 part of Calo sulfur accelerator Tsukusela MSA (manufactured by Taiki Shinko Kagaku) was used as the comb layer for the inner and outer surfaces and the topping rubber for the reinforcing fabric. .

As shown in Figure 1, an iron mandrel (1) with an outer diameter of 40φ
First, the rubber fabric was wrapped in a sheet having a thickness of 3 mm to form an inner rubber layer (2). Next, a vinylon-based mesh-like fabric (3) having 6 meshes per inch is treated with resorcinol/formalin latex, and then topped with a thin layer of the rubber fabric on both sides to a thickness of α6. It was wrapped around the inner rubber layer. Next, a 12 mφ mild steel wire (4) was wound spirally on top of it with an 8-inch pitch, and the rubber fabric sheet 21 was further broken to cover the outer surface.

A layer (5) was formed. Note that the wire (4) is not wound around the part (A) approximately 3' Oa from both terminal parts, and a metal ring (6) is fitted therein, and the inner and outer rubber layers (2) are placed so as to surround the metal ring. , (4) and the reinforcing fabric layer (3) were folded back to form a straight tubular hollow molded body having a length of 180 mm.

Before bending this straight tubular hollow molded body, the arrow (A)
As shown in Fig. 2, an outer rubber layer (
A rubber fabric tonto (7) with the same 2cm thickness as in 5) was pasted together, and the molded body was pulled out from a straight mandrel, gradually inserted into a separately prepared straight mandrel, and bent at an angle of 90 degrees.

The obtained unvulcanized bent hollow molded body is pulled out from the i-bend mandrel, a pladder made of plastic rubber tube is inserted into the hollow part of the hollow molded body, and set in an iron mold. Apply an internal air pressure of 8 to 10 t/- to
Vulcanization was carried out at 170°C for 15 minutes. Thereafter, the vulcanized product was removed from the mold, deburred, and then a flange (8) was attached to obtain a final product. JI in the outer rubber part of the final product
The SA hardness is 55°, and the deviation angle is 15° as shown in Figure 3.
The pressure characteristics measured by setting the temperature at 10°C were as shown in Example 1 in Table 1.

Example 2 A bent rubber tube was made in exactly the same manner as in Example t except that the outer diameter of the straight tube mandrel was changed to 50g3, and the pressure characteristics were measured.The results are shown in the column of Example 2 in Table 1. It was shown to.

Table 1 However, rain restraint is defined by the lengths of the two sides Dl and D shown in Figure 3.
2 respectively D + '' 100■, D, = 12〇- and declination ((= indicates the test with the state held at Q, and "unrestrained" means the test without being held, so as the internal pressure increases, It shows the behavior of trying to become a straight tube.

As can be seen from Table 1, the rubber curved tube of the present invention has a negative pressure resistant cuff of 60 mm Hf and has sufficient performance to be used for conventional high decompression applications, and the method of the present invention is adopted. This enabled mass production with good reproducibility even by unskilled workers.

Furthermore, as shown in Table 2, the rubber bent pipe obtained by the method of the present invention has a significantly smaller load value required to displace it by a certain amount than the conventional product listed as Comparison 91j. It shows that the reaction force when the body is displaced is small, and of course there is no negative effect on the tank body.If the body is displaced, it can be followed very easily, and it has a spiral shape. Thanks to the wire reinforcement installed at the top, there was no need to worry about buckling.

Table 2 However, the measurement results in Table 2 apply when one flange (8) is fixed and the other 7 flange (8) is fixed as shown in Figure 3.
) is applied a load in the vertical direction and displaced by a predetermined amount, and the load value at each displacement is read.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the hollow molded article of the present invention at the stage of being formed into a straight tube shape, and FIG. 2 is a cross-sectional view along the line X-X in FIG.
FIG. 3 is a side view showing the pressure characteristics and load displacement measurement conditions of the rubber sag pipe of the present invention. 1, ... mandrel 2, ... inner rubber layer 31. ...Reinforcement cloth 4, ...Metal wire 5...Outer rubber layer 6...Metal ring 7...Rubber note 8.8... ...7 range patent applicant Toyo Tire & Rubber Industries, Ltd.

Claims (1)

[Claims] When forming a straight tube-shaped hollow molded body by winding an inner rubber layer, a reinforcing cloth layer, a metal wire reinforcing layer, and an outer rubber layer around a straight tube mandrel in this order, a fabric or net-like material having elasticity as a reinforcing cloth is used. A metal wire is spirally wound around a layer close to the stretchable reinforcing fabric layer at a pitch ranging from 1/2 to 1/10 of the diameter of the straight tubular hollow molded body, and an outer surface covering the outer surface A method for manufacturing a bent rubber tube, characterized in that the rubber layer is formed to have a thickness on the outer circumferential side thicker than the inner circumferential side when formed into a bent tube, and then is bent and formed using a bent tube mandrel.