JP3380006B2 - Fusion joint and method for joining fusion joint to pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for joining gas pipes, water pipes and the like made of thermoplastic resins such as polyethylene, polypropylene, polyvinylidene fluoride, etc., and particularly to prevent eccentricity and omission when joining pipes. TECHNICAL FIELD The present invention relates to a fusion joint that is effective in preventing it, and a method for joining the fusion joint and a pipe.

[0002]

2. Description of the Related Art When joining a fusion joint and a pipe, the end of the pipe is inserted into the socket of the fusion joint, and the energization heating element arranged inside the receiving port is energized to heat it. Thermal fusion bonding is generally performed in which the resin of the fusion joint near the body and the resin of the pipe are melted and expanded to be fused and joined. The inner diameter of the fusion-bonding joint used for such heat-fusion bonding is slightly larger than the outer diameter of the pipe, and there is a gap between the inner surface of the receptacle and the outer surface of the pipe.

However, since the gap is increased as the diameter is increased, if a gap is attempted to be fused while the gap is non-uniform due to a poor support method of the fusion machine or the influence of gravity, the gap is large. In some parts, the receptacle and the pipe are not completely fused, and as a result, an accident may occur due to fluid leakage or poor joint strength. Therefore, it is important to keep the gap between the inner surface of the receiving port and the outer surface of the tube uniform.

In addition, since the pipe may come out of the receiving port due to the above-mentioned gap and the fusion may not be completely performed in the same manner, it is possible to prevent the pipe from coming off before and during the fusion. It is important to.

Therefore, as a fusion splicer which does not cause unevenness of the gap between the inner surface of the receiving port and the outer surface of the pipe in the above-mentioned heat fusion bonding, or the pipe coming off, for example, Japanese Patent Laid-Open No. 5-106775.
What is described in Japanese Patent Publication is known. This fusion-bonded joint cuts into the joint body as it moves in the cold direction (zone outside the heat zone in which the electric heating element is embedded) in the inner circumference of the joint body and moves into the joint body as it moves in the pull-out direction. A pipe withdrawal preventing means for preventing slipping out is provided, and as a concrete pipe withdrawing preventing means, an annular recess having a conical surface whose inner diameter is reduced toward both ends to the inner peripheral portion of the cold zone is the inner bottom surface. And a steel biting member having a C shape in a side view is fitted into the annular recess.

In the fusion splicing described in the above-mentioned JP-A-5-106775, when a pipe is inserted into its receiving port and an attempt is made to move the pipe in the pulling direction, the biting member bites into the pipe and prevents the pipe from falling out. At the same time, the inner surface of the receiving port of the fusion splicer and the outer surface of the pipe are centered so that the gap becomes uniform, the fusion performance can be obtained without variation, and the welding workability is excellent.

[0007]

However, in the fusion splicing described in Japanese Patent Laid-Open No. 5-106775, since a steel biting member is provided on the inner peripheral surface of the inlet portion of the receiving port, corrosion is caused. When the insertion member touches the outer surface of the tube when inserting the tube or digs into the outer surface of the tube when it is prevented from coming off, the outer surface of the tube is damaged, resulting in defective fusion due to scratches and stress concentration on the damaged part. Fluid leakage and joint damage may occur.

The present invention has been made in view of the above-mentioned problems of the prior art, and solves the problems of the prior art and, when fusion-bonding the pipe and the fusion joint, the inner surface of the receiving port and the outer surface of the pipe. The gap between and can be adjusted uniformly and easily, and the tube inserted into the receiving port can be securely held without coming out. Also, when inserting the pipe into the receiving port or preventing the pipe from falling out. An object of the present invention is to provide a fusion-bonded joint in which the outer surface of the pipe is not damaged, and a method for joining the fusion-bonded joint and the pipe.

[0009]

In order to achieve the above object, the fusion-bonding joint of the present invention according to claim 1 is made of a thermoplastic resin, and a pipe end portion of the thermoplastic resin pipe is inserted. A fusion splicer in which a receiving port is formed, a main energizing heating element is embedded in the inner peripheral surface of the central part of the receiving port, and an auxiliary energizing heating element is embedded in the inner peripheral surface of the inlet part and the inner part of the receiving port. The main point is that the heating current and the heating time can be controlled separately for the main energization heating element and the auxiliary energization heating element.

According to a second aspect of the present invention, there is provided a method for joining a fusion joint and a pipe, wherein the pipe is inserted into the receptacle of the fusion joint according to the first aspect, and the sub-heating element is energized to receive the receptacle. The point is to heat and expand the resin at the inlet and back of the resin to a temperature below the melting temperature, and then to energize the main energization heating element to heat the fusion joint and the tube to the melting temperature for fusion and bonding. To do.

[0011]

According to the present invention, the main energization heating element and the sub-conduction heating element can control the heating temperature and the heating time separately. It is possible to adjust the heating timing and the heating temperature for the centering of the portion and the prevention of the tube from coming off, and for the fusion of the central portion of the receiving port by the main energization heating element to be optimum.

According to the second aspect of the present invention, the sub-heating element is first energized and heated to a temperature not higher than the melting temperature, whereby the resin at the inlet and the inner part of the receptacle expands to form the outer surface of the pipe. Centering is performed so that the gap between the inner surface of the receiving port at the center where the main energization heating element is embedded and the outer surface of the pipe is almost uniform, and the resin slightly softens due to the temperature rise, and the receiving port and pipe Has a large friction coefficient, and the pipe inserted in the receiving port is held without coming out.

Then, the main energizing heating element is energized to heat the fusion joint and the pipe to a melting temperature, whereby the fusion joint and the pipe are fused and joined.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings by embodiments. FIG. 1 is an explanatory view showing an example of the fusion-bonding joint of the present invention according to claim 1, (A) is a longitudinal sectional view, (B) is a front view, and FIG. FIG. As shown in FIG. 1 (A), a single-ended socket 1 (fusion joint) made by injection molding of polyethylene resin is butt-fused to one end of a pipe P ₁ made by extrusion molding of polyethylene resin. It is regarded as a single-sided straight pipe.

At the center of the inner peripheral surface of the receiving port 2, a wide main energizing heating element 3 in which a nichrome wire is spirally wound is buried in most of the area, and the main energizing heating element 3 is provided. Both ends of are connected to two terminals 4 and 4 protruding on the outer surface.

Further, sub-heating elements 5 and 6 having a narrow width and similarly wound with a nichrome wire are embedded at the entrance and the back of the receptacle 2 with the main heating element 3 interposed therebetween. The sub-heating elements 5 and 6 are connected in parallel to the two terminals 7 and 7 projecting from the front end of the single-ended socket 1. Therefore, the terminals 4 and 4 are connected to a main energization heating element controller (not shown) to control the heating of the main energization heating element 3, and the terminals 7 and 7 are connected to a sub energization heating element controller (not shown) to generate sub-conduction heating. The heating control of the bodies 5 and 6 can be performed separately.

It is to be noted that the auxiliary energization heating elements 5 and 6 have a capacity smaller or a setting value of the auxiliary energization heating element controller is set low so that the receiving port 2 in the vicinity thereof has a melting temperature or lower. It is set to be heated to an extremely low temperature (preferably about 120 ° C.).

Next, a method of joining the one-ended socket 1 and the pipe P ₂ will be described with reference to FIG. First, when the terminal 7 is energized, the auxiliary energization heating elements 5 and 6 generate heat, and the receiving port 2 and the pipe P _{2 in the} vicinity thereof are heated to a temperature equal to or lower than the melting temperature and are expanded to expand the inner surface of the receiving port 2 and the pipe P _2. the outer surface is in contact, the main energization heater 3 is almost uniform and so as to centering clearance c of the receiving 2 inner surface and the pipe P ₂ of the outer surface of the central portion which is embedded over the entire circumference is made.

Further, since the inner surface of the receiving port 2 and the outer surface of the pipe P ₂ are in contact with each other and the resin is slightly softened by the temperature rise to increase the friction coefficient, the pipe P ₂ is easily removed from the receiving port 2. It is held without getting out.

Next, when the energization of the auxiliary energization heating elements 5, 6 is stopped and the terminals 4, 4 are energized instead, the main energization heating element 3 generates heat, and the resin in the vicinity thereof is heated, melted and expanded. ,
Most of the inner surface of the receiving port 2 and the outer surface of the pipe P ₂ are fused and the single-ended socket 1 and the pipe P ₂ are joined.

Since the fusion splicing joint 1 of the present invention has no means for preventing the pipe P ₂ from slipping out of the receiving port 2 other than the sub-heating elements 5 and 6, the structure is simple and
Without the outer surface of the pipe P ₂ by preventing means omission damaged, stress concentration on the part of the fusion defects and scratches are not generated due to a scratch.

Although the embodiments of the present invention have been described above, the specific configuration is not limited to the above-mentioned embodiments, and the present invention also includes design changes and the like without departing from the scope of the present invention. For example, in the examples, the nichrome wire is spirally wound as the energization heating element, but the copper-nickel alloy wire is spirally wound, the conductive fiber such as carbon fiber or its cotton shape, It may be a processed product in the form of a wire, a net, a sheet, etc., or a laminate thereof, or a product that generates heat by high frequency induction heating.

[0023]

As is apparent from the above description, claim 1
Although the fusion splicing joint of the present invention described has a simple structure including only a main-conduction heating element and a sub-conduction heating element, the heating temperature and heating time of the sub-conduction heating element are set to the heating temperature of the main-conduction heating element. By controlling the heating time and heating time separately, the gap between the inner surface of the receiving port and the outer surface of the pipe can be adjusted uniformly, and the pipe can be prevented from coming off from the receiving port, so that highly reliable fusion bonding can be obtained. It is possible to easily carry out the joining work.

Further, since there is no centering means or drop-out preventing means protruding to the inner surface of the receiving port, there is no fear of damaging the outer surface of the tube by these centering and slip-out preventing means, and there is no possibility of defective fusion due to scratches. It is possible to avoid stress concentration.

According to a second aspect of the present invention, there is provided a method for joining a fusion splicing joint and a pipe, in which a main current-carrying heating element is first energized and heated so that the main current-carrying heating element is embedded in the inner surface of the receptacle. The gap between the outer surface of the pipe and the outer surface of the pipe is adjusted uniformly, and at the same time, the pipe is prevented from coming out of the receiving port, so that highly reliable fusion bonding can be obtained.

Further, since it is not necessary to provide a separate means for preventing the tube from coming off, there is no fear of damaging the outer surface of the tube, and it is possible to avoid defective fusion and stress concentration due to scratches.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of the fusion splicing joint of the present invention,
(A) is a longitudinal sectional view, and (B) is a front view.

FIG. 2 is a vertical cross-sectional view showing a mode of use of the fusion splicing joint of the present invention.

[Explanation of symbols]

1 Single-ended socket (fusion joint) 2 Receptacle 3 Main energization heating element 4 Terminal (for main energization heating element) 5,6 Sub energization heating element 7 Terminal (for sub energization heating element) c Gap P ₁ , P ₂ pipe

Claims (2)

(57) [Claims] 1. A receiving port made of a thermoplastic resin, into which a pipe end of a thermoplastic resin pipe is inserted, is formed, and a main energization heating element is embedded in an inner peripheral surface of a central part of the receiving port. It is a fusion splicer in which the sub-heating element is embedded in the inner surface of the inlet and the inner part of the mouth.The heating temperature and heating time of the main heating element and the sub-heating element can be controlled separately. Fusion-bonded joint characterized by being 2. A tube is inserted into the receptacle of the fusion joint according to claim 1, and the auxiliary energizing heating element is energized to heat and expand the resin at the inlet and the back of the receptacle to a temperature below the melting temperature. A method for joining a fusion joint and a pipe, characterized in that the main energization heating element is energized to heat the fusion joint and the pipe to a fusion temperature to fuse and join.