JPH0225776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an FRP joint for use in piping materials for transporting high-temperature, high-pressure acid/alkaline aqueous solutions, and more specifically to a method for forming an FRP joint using a resin injection method. It is something.

Conventionally, joints for plant piping that transport high-temperature acids and alkaline solutions have been plated inside special metal joints or lined with special resin to improve corrosion resistance and prevent high-temperature deterioration. However, because the bonding force with the metal is weak, the plating and lining film may peel off and reduce the performance of the joint, so plating and lining work must be repeated each time, and after piping, In many cases, such work cannot be done, and the pipes must be replaced after all.
There were various problems such as high cost and troublesome piping work.

The present invention was made to solve these conventional problems, and its purpose is to continuously mold FRP joints using a mold in almost the same molding cycle as injection molding of thermoplastic resin. and appearance,
Able to mold products with high performance and high quality.
The objective is to provide a method for forming FRP joints.

That is, in order to achieve this objective, the present invention
The molding method for FRP joints is based on the resin injecting method. Joints such as cheese joints and elbow joints are formed in advance using heat-resistant vinyl chloride resin, and a continuous joint is formed on the outside of this joint. The strand mat is wrapped around it, and then placed in a mold having a cavity slightly wider than the outer shape of the joint, a thermosetting resin is injected into the mold, and heat is applied to the continuous strand mat. The structure is such that the joint and the continuous strand mat are integrally molded by impregnating and curing a curable resin.

Embodiments of the present invention will be described below with reference to the drawings. First, after winding a cotton-like continuous strand mat 2 to the required thickness on a heat-resistant vinyl chloride cheese joint (hereinafter referred to as "HT joint") 1 with a designation of 25 m/m, a space of the same shape is Mold 3 having a cavity slightly wider than joint 1
Put it inside. The mold 3 is formed into two halves, upper and lower. After putting the above-mentioned HT joint 1 into the lower mold 3b and closing the upper mold 3a, unsaturated polyester resin is injected from a part of the mold 3. , an unsaturated polyester resin is impregnated into the continuous strand mat 2 and allowed to harden naturally.

Next, in the same way as above, attach continuous strand mat 2 to another mold 3 on top of HT joint 1.
After putting in the wound material and sealing it, unsaturated polyester resin is injected to impregnate the continuous strand mat 2 with the resin and harden naturally to form the FRP joint A.

In addition, in the injection molding method normally used,
A large number of products can be molded in one cycle by fixing the mold, injecting resin, and cooling and hardening it. However, in the method of this embodiment, a large number of molds 3 can be rotated. After fixing it on the support plate 4 that can be used and injecting the thermosetting resin into the mold 3 through the nozzle 5,
The support plate 4 is rotated so that the nozzle 5 communicates with the injection port 6 of the next mold 3, and the thermosetting resin is injected and allowed to harden naturally.

In this way, continuous production is carried out while injecting thermosetting resin into the molds 3 fixed on the support plate 4 one after another.

In addition, as an embodiment of the present invention, a continuous strand mat is wound around a cheese joint with a nominal diameter of 25 m/m, and then unsaturated polyester resin is injected to form an FRP layer with a thickness of 2 m/m. As a result of testing, it showed a hydraulic breakdown value of 110Kg/cm ² in hot water of 100℃. By the way, the blank HT joint deformed immediately when 100℃ hot water was passed through it.

In order to complete the present invention, it is necessary to uniformly impregnate the unsaturated polyester resin into the glass fibers at a low injection pressure. To achieve this, it is important that the glass fibers are not swept away even when the unsaturated polyester resin passes through them at a considerable speed. Many tests were conducted to find a glass fiber that satisfies this requirement. The results showed that continuous strand mats were the most suitable.

In other words, the continuous strand mat is
Since it is made of continuous strands stacked in layers, it has elasticity in the thickness direction, so even if unsaturated polyester resin is injected at a considerable speed, the mat will not be washed away, and if there are fluctuations in wall thickness, it will not be washed away. Because it has elasticity in the thickness direction, it works to prevent cracks from occurring in the product, and it also allows gases such as air remaining between the joint and the glass fiber to be smoothly removed. In the method, it is difficult for gas to escape, so secondary processing is required to prevent unevenness on the product surface, but in the present invention,
Even if a continuous strand mat is wrapped directly over a joint that has an uneven outer surface and unsaturated polyester resin is injected, no gas remains at the interface between the mat and the joint, and no adhesive peeling occurs from the interface. tensile,
It is capable of holding a significantly large cord pressure and load.

Although one embodiment of the method of the present invention has been described above based on an HT cheese joint, it goes without saying that the method of the present invention can be applied to various sizes of HT elbow joints, HT socket joints, HT reducers, and HT bend joints. By using multiple molds,
The molding cycle can be shortened to less than one minute, similar to injection molding.

As described above, according to the method of the present invention, a continuous strand mat is wound around the outside of an HT joint to a required thickness, and then placed in a mold and injected with an unsaturated polyester resin. Uniformly impregnated with resin and integrated with the HT joint, it is resistant to heat, acid, and alkali.
This allows FRP joints to be formed efficiently, and the appearance is more beautiful than the previous handrail joints.
HT joints do not deform in any way even with the high heat generated during curing of unsaturated polyester resin, so they do not lose their shape and can be reliably connected to pipes.

In addition, since it is molded using a mold, there is little variation in product weight and physical performance can be maintained at a constant level, making it possible to provide FRP joints with stable quality.

Furthermore, since a pre-formed joint is used, it is possible to mold an FRP joint with high internal dimensional accuracy. In addition, since the molding method is based on the resin injection method, molds and resin injectors can be manufactured at low cost, and one resin injector can inject resin into dozens of molds. , the device can be manufactured at a lower cost than a press molding machine.

[Brief explanation of drawings]

Figure 1 is a front view of the FRP cheese joint, Figure 2 is
A front view of a continuous strand mat wound around an HT joint, Fig. 3 is a perspective view showing the main parts of the method of the present invention, and Fig. 4 is a cross-sectional view of an FRP joint formed by the method of the present invention. FIG. 5 is a perspective view showing an example of a molding device. A: FRP joint, 1: Heat-resistant PVC cheese joint, 2: Container strand mat,
3: Mold.

Claims (1)

[Claims] 1. A method for forming FRP joints using a resin injection method, in which a joint such as a cheese joint or an elbow joint is formed in advance from heat-resistant vinyl chloride resin, and a continuous joint is formed on the outside of the joint. The strand mat is wrapped around it, and then placed in a mold having a cavity slightly wider than the outer shape of the joint, a thermosetting resin is injected into the mold, and heat is applied to the continuous strand mat. A method for molding an FRP joint, comprising impregnating and curing a curable resin, and integrally molding the joint and a continuous strand mat.