JPH0715239B2 - Molding method of pipe joint for propulsion method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pipe joint used in a propulsion method performed when a sewer pipe, a cable protection pipe or the like is buried in the ground.

[0002]

2. Description of the Related Art In the propulsion method, a front side propulsion pipe is connected to a screw, and the front side propulsion pipe is pressed into the ground by pressing it with a propulsion device arranged in a vertical shaft, and then the front side propulsion pipe is connected to the front side propulsion pipe. By connecting the rear propulsion pipes through the pipe joint, pressing the rear propulsion pipes again with the propulsion device and press-fitting them into the ground, the required number of propulsion pipes are buried in the ground. It goes.

Conventionally, as a pipe joint used in this propulsion method, for example, one described in Japanese Utility Model Laid-Open No. 63-156295 is known. In this conventional pipe joint, a rib in the pipe axial direction is formed on the outer peripheral surface of the joint body over the entire length of the joint body. This pipe joint increases the bending strength of the joint body due to the ribs formed on the outer peripheral surface of the joint body,
The thickness of the joint body can be made thinner by that much, and the rib can accurately maintain the propelling direction of the propulsion pipe.

[0004]

However, in the above-mentioned conventional pipe joint, although the bending strength is increased by the rib, the wall thickness is thin and the rib receives the impact force in a concentrated manner, so that the overall impact resistance is high. There is a problem that it is inferior in strength and easily damaged. Further, since the conventional pipe joint described above has weak strength in the circumferential direction, pushing force of the propulsion pipe when inserting the propulsion pipe from the pipe receiving ports on both sides and pushing it in until the tips of the propulsion pipes come into contact with each other is connected. There is also the problem of being unable to withstand and being damaged.

The molding method of the pipe joint for propulsion method of the present invention is as follows.
The present invention has been made in view of the above-mentioned problems, and the purpose thereof is for a propulsion construction method that is excellent in bending strength and impact resistance even if the wall thickness is thin, and is also excellent in circumferential strength. It is to provide a method for forming a pipe joint.

[0006]

In order to achieve the above object, in the method for forming a pipe joint for a propulsion method according to the present invention, a taper shape that opens outward from a central portion toward openings on both left and right sides is formed by a hard vinyl chloride resin. After forming a raw pipe having an expanded diameter, and laminating glass fibers impregnated with a thermosetting resin on the outer periphery of the raw pipe, the FRP with ribs is added while the thermosetting resin is uncured.
A method was adopted in which the plate was wound so that the ribs were aligned with the pipe axis direction of the original pipe, and integrally molded.

[0007]

In the method for forming a pipe joint for a propulsion method according to the present invention, since the FRP plate with ribs is wound while the thermosetting resin impregnated in the glass fiber is uncured, air is removed from the thermosetting resin. The FRP plate with ribs can be adhered while performing. Therefore, according to the method of the present invention, it is possible to form a pipe joint having a dense FRP layer, and it is possible to form a pipe joint having a large circumferential strength and capable of sufficiently withstanding the pushing force of the propulsion pipe. Further, in the molding method of the present invention, since the intermediate layer and the outer layer are formed of FRP and the ribs in the pipe axial direction are formed on the outer circumference, a pipe joint excellent in impact resistance and bending strength can be formed. . Further, in the molding method of the present invention, the work is almost manual, but the facility cost is significantly lower than that in the case of manufacturing an injection mold, so that the manufacturing cost can be reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a method for forming a joint for propulsion method according to this embodiment, and FIG. 2 is a sectional view showing a use state of a pipe joint formed by the method for forming a joint for propulsion method according to this embodiment. .

First, a straight tubular hard vinyl chloride resin short tube is processed, and as shown in FIG. 1 (a), an outward opening tape is opened from the central portion 1 toward the tube receiving openings 2 on the left and right sides. A raw pipe 3 having a diameter that is expanded like a pear is formed. As the method for molding the raw pipe 3, a sleeve molding method in which a short pipe made of a hard vinyl chloride resin that has been softened by heating is fitted into a mold having a fitting port shape and then cooled and hardened, or a mold having an outer shape of the fitting is used. A blow molding method in which a short tube made of hard vinyl chloride resin that has been softened by heating is sealed at both ends and expanded into a joint shape by applying air pressure to the inside and then cooled and hardened to mold it, or the reverse of blow molding. There is a vacuum forming method in which a short pipe made of a hard vinyl chloride resin, which is made air-free and heated and softened, is formed by following a mold. The inner surface of the raw pipe 3 is formed so as to have a taper shape in which the inner diameter of the deepest part is slightly smaller than the outer diameter of the propulsion pipe 4. The raw pipe 3 is formed of a hard vinyl chloride resin in order to improve the adhesiveness with the propulsion pipe 4 made of a hard vinyl chloride resin and to facilitate the socket forming process by heating.

Next, a primer 5 is applied to the outer circumference of the raw pipe 3 as shown in FIG. 1 (b). As the primer 5, an isocyanate-based primer is used. still,
When a resin having excellent adhesiveness to the raw tube 3 is used as the thermosetting resin to be impregnated in the glass fiber laminated on the outer circumference of the raw tube 3, the primer 5 may not be applied. When the unsaturated polyester resin is not used as the thermosetting resin, another primer is used in consideration of the adhesiveness with the thermosetting resin.

Next, as shown in FIG. 1C, the glass fiber 6 for filling is wrapped around the outer circumference of the raw tube 3 coated with the primer 5 and impregnated with a thermosetting resin to impregnate the outer circumference of the raw tube 3. Is flattened, then the intermediate glass fiber 7 is wound on it, and a thermosetting resin is impregnated into the intermediate glass fiber 7, and the intermediate FRP layer 8
To form. A chopped strand mat is used as the glass fibers 6 and 7, and its amount is about 30 to 40% by weight based on the thermosetting resin. As the thermosetting resin, an unsaturated polyester resin having a high fluctuation grade is used in order to remove the air while squeezing out the excess resin when the FRP plate 9 with ribs is wound. The intermediate FRP layer 8 may be formed by spraying glass fiber and resin simultaneously on the outer circumference of the raw tube 3 using an FRP spray-up machine other than the above method.

Next, as shown in FIGS. 1 (d), 1 (e) and 1 (f), ribs 10 having ribs 10 formed on one side of the thermosetting resin in the intermediate FRP layer 8 are in an uncured state. The FRP plate 9 is wound, and a half-pressing die 11 is fitted on the FRP plate 9 to press the ribbed FRP plate 9 against the intermediate FRP layer 8 to bond them while simultaneously bleeding air. Then, after curing for a predetermined time, the pipe joint A is taken out from the mold 11. still,
12 is an outer FRP layer.

The FRP plate 9 with ribs is shown in FIG.
As shown in (h) and (i), the chopped strand mat 14 is placed on the handlay mold 13, the unsaturated polyester resin is impregnated and cured, and then the handlay mold 13 is formed.
Remove and mold. Unsaturated polyester resin is intermediate FR
The same resin as the P layer 8 is used. In this embodiment,
A blend of a general-purpose grade and a soft grade unsaturated polyester resin in a ratio of 1: 1 is used in order to facilitate the winding molding. The FRP plate 9 with ribs may be formed by FRP press molding other than the above method.

Therefore, when connecting the propulsion pipes by using the pipe joint A formed by the above-mentioned forming method, as shown in FIG. 2, the propulsion pipes 4 coated with an adhesive on the outer periphery are connected to the pipe receiving ports 2 on both sides. , 2 and push in the end surfaces 4a, 4a until they abut, to bond them. At that time, a spreading force acts on the pipe joint A, but in the pipe joint A of the present embodiment, the intermediate FRP layer 8 and the outer FRP layer 12 are laminated on the outer periphery of the raw pipe 3 to form a three-layer structure, Since the strength in the circumferential direction is large, it will not be damaged by the pushing force.

Further, in the pipe joint A of this embodiment, since the intermediate layer and the outer layer are formed of FRP and the ribs 10 in the pipe axial direction are formed on the outer periphery, impact resistance, bending strength and axial strength are obtained. Is large and will not be damaged during use.

Although the embodiments of the present invention have been described above, the specific structure of the present invention is not limited to the above-mentioned embodiments, and modifications may be made without departing from the scope of the present invention. It is included in the technical scope of the present invention.

[0018]

According to the method for forming a pipe joint for a propulsion method of the present invention, the ribbed FRP plate is wound while the thermosetting resin impregnated in the glass fiber is uncured so that the Since it is possible to wind the FRP plate with ribs while bleeding air, a fine intermediate F
The RP layer can be formed and the FRP plate with ribs and the original pipe can be firmly bonded to each other, and the pipe joint that can increase the circumferential strength and can sufficiently withstand the pushing force when the propulsion pipe is connected can be formed. In the molding method of the present invention, the intermediate layer and the outer layer are made of FRP.
Since the ribs are formed on the outer periphery in the pipe axial direction, the pipe joint excellent in impact resistance, bending strength and axial strength can be formed. Further, in the molding method of the present invention, the work is almost manual, but the facility cost is significantly lower than that in the case of manufacturing an injection mold, so that the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method for forming a pipe joint for a propulsion method according to the present invention.

FIG. 2 is a cross-sectional view showing a pipe joint for a propulsion method formed by the forming method of the present invention.

[Explanation of symbols]

 1 Central part of raw pipe 2 Pipe receiving port 3 Raw pipe 7 Glass fiber (intermediate glass fiber) 9 FRP plate with rib 10 Rib

Claims (1)

[Claims] 1. A hard vinyl chloride resin is used to form a raw pipe whose diameter is expanded outwardly from the central portion toward the pipe receiving ports on the left and right sides in a taper shape, and the outer periphery of the raw pipe is impregnated with a thermosetting resin. After laminating the glass fibers, the FRP plate with ribs is wound and formed integrally while the thermosetting resin is uncured so that the ribs are aligned in the tube axis direction of the original pipe. Forming method of pipe joint for propulsion method.