JPH07148836A - Method and apparatus for bending processing of synthetic resin pipe - Google Patents

Abstract

PURPOSE:To easily perform the bending processing of a synthetic resin pipe by using a synthetic resin pipe having a high frequency dielectric heating layer integrally provided in the thick-walled part thereof as a synthetic resin pipe easily subjected to bending processing and heating the heating layer of this pipe to soften the heated part thereof. CONSTITUTION:A synthetic resin pipe adapted to bending processing is used and the heating of the part to be bent of the synthetic resin pipe is performed by irradiating the high frequency dielectric heating layer 2 provided to the part to be bent with the high frequency electric field from a high frequency electric field generator. By this constitution, the high frequency dielectric heating layer provided to the intermediate part of the pipe is irradiated with the high frequency electric field of the high frequency electric field generator and only the irradiated part is heated and softened to be easily bent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a synthetic resin pipe for bending and an apparatus therefor. The inventor of this application is an inventor of a synthetic resin pipe for bending,
Regarding this tube, Japanese Patent Laid-Open No. 5-101891 (April 1993)
The application is disclosed on the 6th of a month). This invention intends to perform bending by applying a high frequency dielectric heating method to the above-mentioned tube.

[0002]

2. Description of the Related Art Thermoplastic synthetic resin pipes are heat set (heat molded) into various shapes and used in the following manner. For example, a coiled tube made by heat-setting nylon or polyurethane tube (pipe) is used as a hose for industrial, mechanical or air tools, a tube that has been bent in two or three dimensions is used as a fuel tube for automobiles, or Used as a pipe for other industrial parts.

In all of the bending methods for the above-mentioned pipes, the entire pipe and tube are preheated or heated to a required temperature, and under this heating condition, bending and other forming processes are performed, and then a desired shape is obtained through a cooling means. Was getting the product. As the heating catalyst, gas, fluid, or solid (sand, mold) has been used.

[0004]

The conventional bending process is shown in FIG.
As shown in (a), the pipe 1'is heated by a heating device H ', and this is pushed into a mold M'shown in (b) to form two bent portions N', N ', and thereafter the mold is formed. Pipe 1'containing M '
The whole was cooled to manufacture the crank type pipe shown in (c).

As described above, in the conventional heat set, it is a matter of course that the two-dimensional and three-dimensional molding should be performed, and the molding die (sand, metal mold, etc.) must be heated unless it is heated to the bent portion. However, there is a drawback that the entire die (bending device) enclosing the pipe must be cooled when cooling after molding.

The inventor of the present application intends to effectively perform heat setting by using a bending synthetic resin tube which does not require a heating catalyst which has been conventionally required.

As shown in FIG. 9, the above-mentioned bending synthetic resin tube has a tubular body 1 made of a thermoplastic synthetic resin, and a high-frequency dielectric heating layer 2 is not particularly shown in the drawing. It is formed of a high-frequency dielectric heating element obtained by kneading a material having the same quality as or having affinity with a heating material such as metal that is dielectrically heated by a high-frequency electric field, and is denoted by reference numeral 10.

[0008]

In order to achieve the above object, the present invention radiates a high frequency electric field to a bending portion of a bending synthetic resin tube to heat the high frequency dielectric heating element in this portion, and to heat this high frequency dielectric heating element. As a catalyst, it is intended to soften only this portion and perform two-dimensional or three-dimensional molding.

The basic method of the bending method will be described below with reference to FIG. As shown in (a), a high-frequency electric field from the heating electrodes E, E of the high-frequency electric field generator is applied to the bent portions N, N of the pipe 10 to heat the heating element at this portion to weaken it. Next, as shown in (b) of the drawing, it is pushed into the mold M to form a crank mold, and then the pipe 1
By cooling only the bent portions N, N of 0, the crank type pipe shown in (c) can be manufactured.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency electric field generator used in an embodiment of the present invention will be described with reference to FIG. FIG. 2 shows a basic device of the high-frequency electric field generator as a conceptual diagram, in which the heating electrode E is an upper mold 3 and a lower mold 4 which can be opened and closed above and below.
The upper and lower molds are connected by a hinge portion 5, and both molds are provided with a free electric field generating function. Further, a desired cylindrical void C is formed inside the molds. A well-known high-frequency electric field generator having a high-frequency power source and an electric field generating coil is selectively adopted as the both-type generating means.
(See Figure 10)

The following is a description of an embodiment in which bending is performed using the above high-frequency electric field generator, with reference to FIGS. 3, 4 and 10. First step, as shown in FIG. 3, the bending portion of the bending synthetic resin tube 10 is positioned in the cylindrical cavity C of the high-frequency electric field generator A, and this portion is weakened by the heat generated by the heating element 2. . The second step,
As shown in FIG. 4, an L-shaped mold is formed by pushing the softening tube into a bending mold M having a bending shape, and the mold is fixed via a cooling tool W after the L mold is formed.

Another embodiment of the present invention will be described below with reference to FIG. This embodiment shows a case where the invention is applied to a joint of a synthetic resin pipe. In FIG. 5, reference numeral 7 denotes a joint, and a high-frequency dielectric heating element 2 is provided on the cylindrical wall of the joint body 1 of this joint, which has the same structure as the bending synthetic resin pipe described above. .

When connecting the synthetic resin pipes 8, 8 made of the same material to the joint 7, a high frequency electric field is applied with the respective tips of the connecting pipes 8, 8 inserted into the joint 7. The generator E is actuated to heat the heating elements 2 and 2 of the joint body, and this heat melts the connecting portion, so that the joint body and the connecting pipe are welded and solidified.

Other Embodiments FIG. 6 shows a case where a coil ring tube is formed.
The synthetic resin pipe 10 for bending is continuously heated and softened through the high frequency electric field generator E, and the winding drum D is operated to wind the pipe 10 in a coil shape on the surface of the drum to form the resin. The coil ring tube K can be manufactured by quenching afterwards.

By using this method together, it is possible to form a two-dimensional or three-dimensional bent pipe. FIG. 7 shows a case of a large-thickness large-diameter tube. In this case, two high-frequency dielectric heating layers 2 and 2 (heating elements) are formed within the wall thickness of the tubular body 1 as shown in the figure. By operating the high-frequency electric field generators E, E provided on the outer side and the inner side of the bending synthetic resin pipe 10, respectively, the both heating elements 2, 2 are heated at the same time, and the thick portion of this portion is shortened. Venting can be performed after softening with time.

The present invention is not limited to the above-mentioned embodiment, and for example, flare processing of the tip of the pipe or bulging processing for forming a ridge in the middle portion of the pipe is desired by using a jig applicable to that purpose. You can get the product.

[0017]

According to the present invention, a high frequency electric field generator is used to weaken only a desired portion of a synthetic resin tube for bending in which a high frequency dielectric heating layer is integrally formed in an intermediate portion of the synthetic resin tube. While freely bending this part,
A desired mold can be obtained by cooling and solidifying only this portion, and workability can be improved as compared with conventional bending.

[Brief description of drawings]

FIG. 1 is a flow sheet of a processing method of the present invention.

FIG. 2 is an explanatory view of a main part of a high frequency electric field generating device according to the present invention.

FIG. 3 is an explanatory view of a method for bending a synthetic resin pipe for bending, which is a heating device thereof.

FIG. 4 is an explanatory view of a bending method of a bending synthetic resin pipe and a bending apparatus therefor.

FIG. 5 is a cross-sectional explanatory view of a main part when a bending synthetic resin pipe is applied to a joint.

FIG. 6 is an explanatory view of a method and apparatus for forming a bending synthetic resin tube into a coil ring tube.

FIG. 7 is an explanatory diagram of a tube structure and a heating means for heating a large diameter and large thickness tube of a bending synthetic resin tube.

FIG. 8 is an explanatory diagram of a conventional heat set.

FIG. 9 is an explanatory view of a bending synthetic resin tube.

FIG. 10 is a diagram illustrating the operation of the high frequency electric field generator.

[Explanation of symbols]

 1 tube 2 heating layer (heating element) 3 upper mold 4 lower mold 7 joint 8 synthetic resin pipe for connection A high-frequency electric field generator E high-frequency power supply H high-frequency power supply K coil ring tube N bent part W cooling tool

Claims (2)

[Claims] 1. A synthetic resin tube for bending, in which a high-frequency dielectric heating layer 2 is integrally formed in a tubular body 1, is heated by a high-frequency electric field generator only at a portion to be bent, and this portion is softened. The bending process of the synthetic resin pipe for bending is characterized in that the pipe in the above state is pushed into a bending mold to perform bending, and immediately after that, this portion is cooled to perform bending. . 2. A high frequency electric field generator for use in the bending method according to claim 1.