JPS6344532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a pressure-resistant flexible laminated pipe used for transferring high-pressure fluid.

The present invention is a pressure-resistant soft laminate that increases the degree of adhesion between the reinforcing net interposed in the inner and outer resin layers and the inner and outer resin layers, strengthens their integration, and stabilizes quality and improves durability. The purpose is to provide a method for manufacturing pipes efficiently and at low cost.

The present invention will be specifically described below based on embodiments shown in the drawings. The illustrated embodiment consists of three steps: forming the tube for the inner layer, sheathing the reinforcing net, and forming the sheath for the outer layer.

In the tube forming process for the inner layer pipe, a tube 1 having predetermined inner and outer diameters and a unit length of 100 m or 200 m is formed using a soft thermoplastic synthetic resin as a material using an extrusion molding machine. During molding, the outer surface of the tube 1 is directly cooled with air, water, etc., but this cooling effect is difficult to reach the inside of the tube 1, and since the tube 1 is very long, the heat inside the tube 1 is released. It is also not easy to do so. Therefore, residual heat remains inside the tube 1 immediately after molding, and the inner surface of the tube remains soft and easily deforms. Therefore, the tube 1 cannot be transferred to the next process or stored in this state, so the tube 1 is once wound onto a winding frame. However, if the tube 1, which has residual heat and is easily deformed, is wound into the winding frame as it is, the tube 1 will become flat due to the pressing force during winding and the winding force generated when double or triple winding occurs. This causes curls to form, making subsequent work virtually impossible.

In order to prevent this, in the present invention, both ends of a long tube with residual heat are closed and compressed air at a constant pressure is sealed inside the tube.
to a predetermined internal pressure (in this example, absolute pressure 0.1 to 0.2
Kg/cm ² and this is taken as the primary pressure. ) is applied (Fig. 1) and then wound onto the reel body. This makes it possible to maintain the tube in a perfect circular shape and prevent it from curling, and also to maintain the shape of the tube constant during subsequent processes, so that it can be used for knitting reinforcing nets, outer layer coating, etc. The work can be done accurately and smoothly, and the quality of the finished product can be made good.

After the tube 1 thus formed is cooled and hardened, it is transferred to the reinforcing net wrapping process described above. In this step, a braiding machine is used to braid a large number of threads 2a, 2a... on the outer peripheral surface of the tube 1 while maintaining a constant angle, and a reinforcing net 2 having uniform stitches is wrapped (second figure). When wrapping the reinforcing net, a certain tension is applied to the thread 2a and it is wound around the tube, so that the reinforcing net 2 is in a tensioned state. In order for the reinforcing net 2 to maintain its tension, the tube 1 itself must have shape retention or tension, but since the tube 1 is filled with compressed air as described above, these conditions are not met. is fulfilled. In this embodiment, by tightening the reinforcing net 2, the internal pressure of the tube 1 is increased to an absolute pressure of 0.3 to 0.5 Kg/cm ² (secondary pressure).

The intermediate product 3, in which the reinforcing net 2 is tightly wrapped around the outer periphery of the tube 1, is wound up again into the winding frame body and transferred to the above-mentioned step of forming the outer tube covering portion. In this step, the intermediate product 3 is passed through an extrusion molding machine and coated with an outer layer resin. That is, as shown in FIG. 3, it is equipped with an extrusion molding machine that continuously extrudes a thermoplastic synthetic resin (outer layer resin) 4 in a high temperature molten state along the shape of a die 5 and a nozzle 6, and also extrudes the intermediate product 3 in one direction. The intermediate product 3 is continuously progressed to pass through the die 5 and the nozzle 6 to form an outer layer pipe coating portion (outer layer resin portion) 7 on the outer periphery of the intermediate product 3. The intermediate product 3 is fed into the die 5 while its surface is heated. On the other hand, the high-temperature outer layer resin 4 extruded from between the die 5 and the nozzle 6 merges with the outer peripheral surface 8 of the tube 1 and comes into close contact with it. At the time of this merging, the skin layer 8a of the tube 1 reaches approximately the same temperature as the outer layer resin 4 and melts, and the inside of the tube 1 also softens. At the same time, the compressed air inside the tube 1 expands thermally due to the high heat of the outer layer resin 4, and as a result, the tube 1 tends to expand. However, since the outer peripheral surface 8 of the tube 1 is covered with a reinforcing net 2 under tension, the expansion of the tube 1 as a whole is prevented, and only the portions of the net 2 other than the threads, that is, the portions of the stitch spaces 9, 9, etc., expand. I will do it. On the other hand, the thread 2a will be wedged into the outer peripheral surface 8 of the tube.

Thereafter, when the tube 1 is cooled by passing through the cooling device 13, the outer resin portion 7 is formed on the outer periphery of the tube 1, and the threads 2a, 2a... bites into the grooves 11, 11..., 12, 12...
is formed. Naturally, the cross-sectional shape of the finished product will be perfectly circular.

As described above, the present invention comprises hardening a soft thermoplastic synthetic resin tube 1 with both ends closed and enclosing compressed air at a constant pressure, and wrapping the tube with a reinforcing net 2 having a uniform mesh in a rolled-up state. The material is passed through the die and nozzle of an extrusion molding machine, and the resin 4 for the outer layer in a high temperature molten state is merged and tightly adhered to the outer periphery of the tube 1, and the tube 1 is expanded using the high heat of the resin 4 for the outer layer. At the same time as softening, due to the expansion of the compressed air inside the tube 1,
The tube 1 is bulged into the mesh space 9 of the reinforcing net 2, and the reinforcing net 2 is tightly joined between the tube 1 and the outer resin portion 7, thereby integrating the three. do. The pressure of the compressed air sealed in the tube 1, the temperature of the molten resin 4, the passage speed of the tube 1 in the extrusion molding machine, etc.
must be set to such a value that it bulges out sufficiently into the stitch space 9 of the reinforcing net 2 to form the groove 11. Therefore, in the above embodiment, the primary pressure inside the tube 1 is an absolute pressure of 0.1 to 0.2 Kg/cm ² , and the secondary pressure due to tightening of the reinforcing net 2 is an absolute pressure of 0.3.
Although the pressure is set at ~0.5 Kg/cm ² , the present invention is not limited to such a stepwise pressurization method or to this numerical value. Further, as the material for the tube 1 and the outer resin portion 7, it is preferable to use polyvinyl chloride or polyethylene, and as the material for the reinforcing net 2, Tetron, nylon, metal, etc. have high strength and are heat resistant. It is best to use a wire with little physical change.

Thus, the product obtained by the manufacturing method of the present invention not only maintains a perfect circular shape as described above, but also has extremely good adhesion between the tube 1 and the outer resin portion 7, resulting in stable quality. Since the reinforcing net 2 is inserted into both the tube 1 and the outer resin portion 7, even if high pressure is applied to the inside of the laminated tube and the laminated tube expands, misalignment will occur at the boundary between the tube 1 and the outer resin portion 7. It is possible to completely eliminate this problem, and it is possible to reliably prevent separation between the two. In the conventional type, as shown in Fig. 5, the reinforcing net c is in contact with the surface of the inner layer tube b, and gaps d and d are formed on both sides of the contact portion, so that there is no gap between the inner and outer layer tubes a and b. Although there has been a drawback that misalignment is likely to occur, this drawback can be corrected according to the present invention. Therefore, according to the present invention, it is possible to provide a pressure-resistant flexible laminated pipe with stable quality and excellent durability.

Further, the present invention utilizes the enclosed compressed air necessary to maintain the shape of the tube 1 during the manufacturing process, and also utilizes the high heat of the molten resin 4 necessary to coat the tube 1 with the outer layer resin portion 7. bulges out into the mesh space 9 of the reinforcing net 2, no special manufacturing equipment or complicated processes are required, and the pressure-resistant flexible laminated pipe can be manufactured efficiently and at low cost.

[Brief explanation of drawings]

1 to 4 show embodiments of the present invention, FIG. 1 is a sectional view of a tube with compressed air sealed inside, and FIG. 2 is a sectional view showing a state in which a reinforcing net is wrapped around the outer periphery of the tube. a, side view b, and FIG. 3 are longitudinal sectional side views showing the process of forming the outer tube coating, FIG. 4 is a cross-sectional view of the finished product, and FIG. 5 is a cross-sectional view of a conventional example. DESCRIPTION OF SYMBOLS 1...Tube, 2...Reinforcing net, 4...Thermoplastic synthetic resin in a high temperature molten state (resin for outer layer), 7...
Outer layer resin part, 9...mesh space of reinforcing net.

Claims (1)

[Claims] 1. Harden a soft thermoplastic synthetic resin tube with both ends closed and compressed air at a constant pressure sealed.
This is wrapped with a reinforcing net having a uniform mesh in a tightly wound state, and is passed through the die and nozzle of an extrusion molding machine to cause the resin for the outer layer in a high temperature molten state to merge and adhere to the outer periphery of the tube, The tube is softened by utilizing the high heat of the outer layer resin, and at the same time, the tube is expanded into the mesh space of the reinforcing net by the expansion of the compressed air inside the tube, and the reinforcing net is connected to the tube and the outer layer resin. A method for manufacturing a pressure-resistant flexible laminated pipe, which is characterized by closely joining the two parts and integrating the three parts.