JPS58167116A - Joining method of flexible synthetic resin pipe - Google Patents

Abstract

PURPOSE:To join the flexible synthetic resin pipes which curve by leaving them wound linearly mutually, also without the generation of a head and strongly, by heating the end parts of the pipes to be joined beforehand and correcting them linearly. CONSTITUTION:When the synthetic resin made pipes which curve by winding them on the drums, etc. are joined mutually, the end parts of the pipes are heated and their shapes are corrected linearly, then the pipes are served to joining. As said heating temperature, when the composing material of the pipe is a thermoplastic resin, the temperature rang of (m.p. of the resin -60 deg.C)-(m.p. of the resin) is preferable and when the composing material of the pipe is a crosslinking or curable resin, the temperature range of (m.p. which the resin has before a crosslinking or a cure -60 deg.C)-(the deterioration beginning temperature of the resin) is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for connecting flexible synthetic resin pipes made of thermoplastic, crosslinkable, or crosslinked, cured synthetic resins.

When connecting synthetic resin pipes to each other with a butt, it is extremely important that the pipes to be connected be compressed with uniform pressure over the entire end surface. The reason for this is that if the compression force is uneven, the areas that are strongly pressed will be sufficiently welded or bonded, but the areas where the pressure is weak will be insufficiently welded or bonded, and leaks will easily occur from those areas. Alternatively, in addition to problems such as weak mechanical strength of the connection part, if the bar connection is accompanied by softening or melting of the pipe end surface, local parts of the pipe wall constituent material may be placed inside or outside the pipe in areas that are strongly compressed. There are also problems such as a so-called bead, which deteriorates the appearance and increases the flow resistance of the fluid passage in the pipe.

By the way, as shown in FIG. 1, when pipes 1 and 1' obtained from drum-wound or bundled flexible synthetic resin pipes are brought into contact with each other due to their curling,
This results in uneven contact, and a good base-to-seat connection cannot be made for the reasons mentioned above.

Flexible synthetic resin pipes are thermoplastic, crosslinkable, or crosslinked.
Synthetic resin 'R(7) x + made of hardened synthetic resin
) - using a joint with a shape of a pipe, socket, seat, elbow, cheese or other shape, and inserting it into the pipe insertion part of the joint;
Alternatively, connect by inserting a fitting into the pipe (
In the following cases [this connection method is referred to as a joint insertion connection], it is desirable to insert the tip of the synthetic resin pipe into the pipe insertion part of the joint so that their central axes coincide; however, if the synthetic resin pipe is wound If the pipe has curls, the above-mentioned ideal insertion is difficult due to the bend in the tip of the pipe, and the second
As shown in the figure, the central axes 1' and 2 of both the pipe 1 and the joint 2 are
' can easily become a state where they intersect. In such an inserted state, the state of welding, adhesion, or pressure bonding between the pipe and the joint is uneven, resulting in a poor connection and leakage of transport fluid from the joint. If one or both of the pipes or fittings to be connected has a high surface hardness or high mechanical strength during insertion and connection, one or both of the pipes and fittings to be connected may have a high degree of softening. brought to temperature,
Therefore, when the connector is inserted and connected while it is in a state where it is easily deformed by external force, it is particularly likely to be in a distorted insertion state as shown in FIG. The reason for this is that due to the large friction between the outer wall of the pipe and the inner wall of the joint during insertion, one or both of the joining walls are likely to be removed, and the space in which the bent part of the removed split pipe is maintained becomes larger. It is.

When connecting pipes in a large area where workers can work freely, it is possible to reduce the degree of connection failures described above due to pipe bends to some extent by using the worker's connection techniques. If the pipe is connected in a location where the worker is in an uncomfortable position, connection failures due to pipe bending are more likely to occur. many.

In view of the above, the present invention provides the following features when connecting a flexible synthetic resin pipe with a curl through a butt connection or a joint insertion connection.
This invention proposes a pipe connection method characterized by straightening the tip of the pipe to be connected into a straight line by heating in advance.

When butt connecting pipes or fitting insertion connections using pipe connecting equipment, at least the part of the connecting equipment that is fixed by the pipe fixing member such as the pipe receiving member and the part up to the tip of the pipe must be heated in advance to form a straight line. Needs to be corrected. Particularly favorable results are obtained if the pipe tip is pre-straightened at least 15 times the length of the straightened section. In the case of manual work without using pipe connecting equipment, etc., it depends on the outside diameter of the pipe, the bending radius in the rolled state, etc., but at least the part from the tip of the pipe that is at least twice the inside diameter of the pipe, especially It is desirable to heat-straighten a portion of length equal to at least five times the inner diameter of the pipe itself.

In the present invention, the tip of the synthetic resin pipe may be straightened by any method, but for example, by applying a metal linear member to the outside of the tip of the pipe, or by applying a metal linear member to the outside of the tip of the pipe, or by Alternatively, insert a metal rod with a slightly smaller outer diameter to force the required length of the pipe tip into a straight line, and hold the pipe at a suitable high temperature for several minutes to remove any bends. Afterwards, it is best to cool it with the linear member attached.In addition, regarding the above heating temperature, if the pipe component is a thermoplastic resin, the temperature should be between 60℃ lower than the melting point of the resin and less than the melting point. If the pipe constituent material is a crosslinked or cured resin, the appropriate temperature is at least 60° C. lower than the melting point of the resin before crosslinking or hardening and below the deterioration start temperature.

When the flexible synthetic resin pipe has a heat insulating layer such as a foam layer on the outside thereof, heating of the correction pot is preferably performed by flowing a high temperature fluid into the pipe.

10 pieces of wall thickness made of uncrosslinked polyethylene that can be water-crosslinked, wound around a drum with a body diameter of 1500 m, and an outer diameter of 120 m.
3m polyethylene pipe is pulled out from the drum.
A connection test piece was prepared by cutting it into long pieces. Of course, each test piece is in an open state. When inserting and connecting the above-mentioned pipe test piece to a sleeve with a wall thickness of 10 m and an inner diameter of 120 mm, the connecting parts of the sleeve and pipe were brought into direct contact with a stainless steel heating tool preheated to 200°C for about 40 seconds, and the inside of the sleeve was heated and connected. The outer surface of the pipe is heated, and then the pipe is aligned with the sleeve as closely as possible with the presence of a thin layer of water-crosslinkable polyethylene adhesive on the inner surface of the sleeve and the outer surface of the pipe. The fitting was inserted and connected with care.

In the above connection, the tip of the pipe test piece on the connection side is approximately 50 mm
In 10 connection experiments using pipe test pieces whose portions between 0 and 0 were straightened in advance using the method described below, no insertion distortion was observed visually as shown in Figure 2. In insertion experiments using pipe test pieces that were not subjected to straightening, insertion distortion was visually observed in 5 of the 10 connection experiments.

On the other hand, the pipe gripping member interval for the above pipe test piece was 500.
9) When connecting using Saku's butt connecting machine, it was found that for those that had been straightened, peads occurred uniformly in the circumferential direction at the connection point, and the connection was uniform across the entire surface of the connection end. However, in the case of pipe specimens that were not straightened, it took a long time to adjust the position of the pipe gripping member due to uneven contact between the pipe end surfaces before heating and compression.
Furthermore, even after the adjustment, the degree of uniform contact between the end faces was generally far inferior to that obtained when straightening was performed.

Straightening method for pipe test piece...Inner diameter 120ffiII kept at 100℃ by electric heating! 1 wall thickness 3fi, length 5
A straight halved pipe made of 00 stainless steel surface is placed over the pipe test piece, the pipe test piece is heated and compressed, and after 5 minutes of heating and compression, the pipe is cooled with the halved pipe attached.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an inappropriate mating state of pipe end surfaces when butt-connecting pipes, and FIG.
FIG. 3 is a cross-sectional view of a pipe and a fitting that are improperly inserted and connected. In FIG. 1, 1 and 1' are pipes, in FIG. 2, 1 is a pipe, 2 is a joint, 1' is the central axis of the pipe 1, and 2' is the central axis of the joint 2. Patent Applicant: Dainichi Nippon Electric Cable Co., Ltd. Yukioden Ikuyama / Zudai 2 times

Claims (1)

[Claims] ■ When connecting drum-wound or bundled flexible synthetic resin pipes by means of a seat connection or by inserting a joint, the tip of the pipe to be connected is heated in advance to straighten it into a straight line. How to connect flexible synthetic resin pipes. U. The flexible synthetic resin pipe has a heat insulating layer on the outside, and the connection method according to claim 1, wherein heating for straightening is performed by flowing a heating fluid into the pipe. .