JPH1027676A - Manufacture of electric heating mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacture of an electric heating mat used in molding of a branched pipe joint burying the electric heating mat mounting an electric heating wire in a reverse surface of an almost semicylindrically curved saddle, so as to prevent a distortion from being left in the electric heating wire when it is wound. SOLUTION: A method of manufacture of an electric heating mat is used in molding of a branched pipe joint burying the electric heating mat mounting an electric heating wire in a reverse surface of an almost semicylindrically curved saddle. A through hole 21 is provided in an almost central part, the method of manufacture comprises a process winding an electric heating wire D along a groove of a metal-made mat 2 providing a spiral groove 22 with this through hole 21 serving as the center, process applying fixed voltage to this electric heating wire D to heat it cooled so as to obtain a spiral electric heating wire 12 removing a distortion at winding time and a process mounting this spiral electric heating wire 12 in a groove of a resin-made mat formed in the same shape to the metal-made mat 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric heating mat used for forming a branch pipe joint in which an electric heating mat having an electric heating wire mounted on the back surface of a saddle curved in a substantially half cylindrical shape is embedded.

[0002]

2. Description of the Related Art Conventionally, as an electric heating mat used for forming a branch pipe joint in which an electric heating mat in which an electric heating wire is mounted on the back surface of a saddle curved in a substantially semi-cylindrical shape is used, for example, Japanese Patent Application Laid-Open No. 7-110994 As shown in FIG. 5, a through hole b is provided substantially at the center of a synthetic resin sheet a, and a spiral groove c is provided around the through hole b,
A heating wire d is provided along the groove c, and a plurality of air vent grooves e extending substantially radially across the spiral groove c are proposed.

[0003]

However, the conventional branch pipe joint in which the electric heating mat is embedded as described above is embedded with the distortion when the heating wire d is mounted along the groove c remaining. Therefore, when a branch pipe is formed in the resin pipe, the pipe is easily deformed when a voltage is applied, and in an extreme case, there is a problem that the heating wire d protrudes from the groove c and may be short-circuited.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and prevents the distortion of the heating wire during winding, so that the heating wire is mounted on the back surface of a saddle curved in a substantially half cylindrical shape. Used for forming branch pipe joints with embedded electric heating mats,
The purpose of the present invention is to provide a method for manufacturing an electric heating mat.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing an electric heating mat used for forming a branch pipe joint in which an electric heating mat having a heating wire mounted on the back surface of a saddle curved in a substantially half cylindrical shape is embedded. A step of winding a heating wire along a groove of a metal mat provided with a through hole at a substantially central portion and a spiral groove provided around the through hole, and applying a constant voltage to the heating wire. And heating and cooling to obtain a spiral heating wire from which distortion at the time of winding has been removed, and forming the spiral heating wire in a groove of a resin mat formed in the same shape as the metal mat. A method for manufacturing an electric heating mat comprising:

In the present invention, to obtain a spiral heating wire in which the heating wire is heated by applying a constant voltage to the heating wire and cooled to remove the distortion at the time of winding, the distortion at the time of winding is applied to the heating wire at a constant voltage. Is applied to heat and cool to anneal the heating wire,
This is to bring the wire into a stable state, and by performing this operation, deformation when the spiral heating wire is energized again can be prevented as much as possible.

[0007]

According to the method of manufacturing an electric heating mat of the present invention, a heating wire is wound along a groove of a metal mat in which a through hole is provided at a substantially central portion and a spiral groove is provided around the through hole. And applying a constant voltage to the heating wire to heat and cool to obtain a spiral heating wire from which distortion at the time of winding has been removed, and forming the spiral heating wire into the same shape as the metal mat. By mounting the resin wire in the groove of the resin mat formed on the heating wire so that no distortion at the time of winding of the heating wire remains,
A branch pipe joint in which an electric heating mat is embedded on the back surface of a saddle curved in a substantially semi-cylindrical shape can be formed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an enlarged part of an example of an electric heating mat manufactured according to the present invention.

In FIG. 1A, reference numeral 1 denotes an electric heating mat, which is provided with a through hole 111 at a substantially central portion and a spiral groove 112 provided around the through hole 111. The spiral heating wire 12 is mounted along the groove 112 in a state where distortion during winding is removed.

As shown in FIG. 1B, the electric heating mat 1 further melts the resin at the boundary between the grooves, closes the opening of the groove, and removes the spiral during winding. Heating wire 1
2 may be used as the electric heating mat 1 '.

The electric heating mat 1 is manufactured through the following steps. First, in the first step, as shown in FIG. 2A, the heating wire D is wound along the groove 22 of the metal mat 2 provided with the spiral groove 22 around the through hole 21. .

In the next step, as shown in FIG.
A constant voltage is applied to the heating wire D for heating and cooling. Thereby, the spiral heating wire 12 from which distortion at the time of winding has been removed is obtained. Further, in the next step, the spiral heating wire 12 is mounted in a groove 112 of a resin mat 11 formed in the same shape as the metal mat 2 as shown in FIG. The electric heating mat 1 on which the spiral heating wire 12 is mounted in a state where the distortion at the time of winding is removed along the groove 112 of the mat 11
Get.

The resin at the boundary between the grooves is melted to close the opening of the groove, and as shown in FIG. 1B, a spiral heating wire 12 from which distortion during winding has been removed is mounted. The electric heating mat 1 ′ may be used.

As shown in FIG. 3, this electric heating mat 1
A branch pipe joint 3 having a saddle 31 curved in a substantially semi-cylindrical shape, and a branch pipe 32 protruding from a substantially center of the saddle 31;
The saddle 31 is used by being buried on the back surface thereof. Such a branch pipe joint 3 is formed by mounting the electric heating mat 1 in a cavity of a mold 4 as shown in FIG. 4 and then injecting a resin into the cavity.

[0015]

According to the method for manufacturing an electric heating mat of the present invention, the back surface of the saddle curved in a substantially semi-cylindrical shape so as not to leave distortion during winding of the heating wire because of the above-mentioned configuration. Since it is possible to mold a branch pipe joint buried in
When a branch pipe is formed in the resin pipe, the pipe is hardly deformed when a voltage is applied, and there is no short circuit of the heating wire.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an electric heating mat obtained by the present invention, wherein (a) is a cross-sectional view showing one example, and (b) is a cross-sectional view showing another example.

FIG. 2 is an explanatory view of steps of an example of a method for manufacturing an electric heating mat of the present invention, wherein (a) is a cross-sectional view illustrating an initial step;
(B) is sectional drawing explaining the next process.

FIG. 3 is a cross-sectional view illustrating a branch pipe joint in which an electric heating mat obtained by the present invention is embedded.

FIG. 4 is a cross-sectional view illustrating a step of forming a branch pipe joint using the electric heating mat of the present invention.

FIG. 5 is a plan view showing an example of a conventional electric heating mat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1 'Electric heating mat 2 Metal mat 3 Branch pipe joint 11 Resin mat 12 Spiral heating wire 21, 111 Through hole 22, 112 Groove

Claims (1)

[Claims] 1. A method of manufacturing an electric heating mat for use in forming a branch pipe joint in which an electric heating mat having a heating wire mounted on a back surface of a saddle curved in a substantially semi-cylindrical shape is embedded. A step of winding a heating wire along a groove of a metal mat provided with a hole and a spiral groove around the through hole, applying a constant voltage to the heating wire, heating and cooling the heating wire A step of obtaining a spiral heating wire from which distortion during winding is removed, and a step of mounting the spiral heating wire in a groove of a resin mat formed in the same shape as the metal mat. A method for producing an electric heating mat.