JPH03129194A - Fusion coupling - Google Patents

Abstract

PURPOSE:To make it possible to produce fusion couplings in a large quantity and to make simply any change of a cross section ratio by making the fusion couplings from electrically conductive thermoplastic resin containing carbon black, metal powder, metallic fiber, or carbon fiber as a filler. CONSTITUTION:Medium density polyethylene resin is mixed with aluminum metal powders to form conductive thermoplastic resin 2, and after that, medium density polyethylene resin is mixed with thermoplastic insulating resin 1 to form the outer peripheral part. Carbon black, metallic fiber, carbon fiber besides metal powders are used as conductive fillers of a heat element and a fusion part. Further, the electrical conductivity of the conductive thermoplastic resin is, for example, 0.01 to 10OMEGA.cm<-1>. As a result, the heat element having heat directivity can be easily produced. Further, phenomena caused by trapped air can be prevented, a uniform fusion part can be obtained, and no residual stress is produced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a joint for connecting water supply, hot water supply, hot water, and gas pipes that are used for buried underground in the walls and floors of houses, etc. The present invention relates to a fusion joint using a conductive thermoplastic resin as a heating element, which allows easy connection.

εPrior Art] An example of a conventional electric fusion joint is the electric fusion joint shown in FIG. 8 disclosed in Japanese Patent Publication No. 63-24820. This is done by bringing two members 51 and 52 made of thermoplastic insulating material into contact with each other with their surfaces facing each other, and by passing current through a coil 55, which is a heating element, provided on a part of the contact surface, a coil is formed. The contact surface of the part becomes the welding zone where the material is heated and melts into the previously inserted pipe adjacent to the welding zone. Here, the coil 55
It takes a lot of effort to attach the coil 55 to the thermoplastic insulating material 51, and at the same time the coil 55 is short-circuited.
There are constraints on the attachment of thermoplastic insulation material 51 to various shapes. At the same time, there are many manufacturing processes.

[Problems to be Solved by the Invention] Here, the above-mentioned coil 55 of the two-layer thermoplastic insulating material 51 and 52 and the heating element were attached due to an operational error or pressure caused during molding of the thermoplastic insulating material 52. Due to short-circuit problems such as twisting of the coil 55 and the inability to generate uniform heat in the heat-generating portion, the surface of the pipe is not uniformly fused, resulting in uneven fusion and residual stress. Furthermore, there are shapes in which it is impossible to attach the coil 55, which is a heating element, even if a lot of effort is spent. In other words, the cross-sectional ratio of the coil 55 is changed depending on the location so that the heating element has heat directivity and air is not entrained in the fused portion, and the coil 55 is held in a spiral shape while drawing a meandering curve in the axial direction. It is very difficult to install.

Therefore, a heating element is needed to uniformly fuse these fused parts, and the present invention provides such a heating element that can be easily and inexpensively manufactured.

[Means for Solving the Problems] According to the present invention, a conductive thermoplastic resin is used as a heating element, mass production by injection molding etc. is possible, the cross-sectional ratio can be easily changed, and thermoplastic resin can be easily changed. We can provide fittings.

According to the first aspect of the present invention, the heating element and the fused portion are made of a conductive thermoplastic resin made of conductive filler such as carbon black, metal powder, metal fiber, or carbon fiber,
By passing a current through the fusion joint by the controller and supplying a certain amount of energy, the fusion joint is melted and fused to the surface of the pipe inserted in advance, allowing easy connection.

According to the second aspect of the present invention, the heating element and the fusion part are made of a conductive thermoplastic resin made of conductive filler such as carbon black, metal powder, metal fiber, or carbon fiber, and the outer peripheral surface is made of a thermoplastic insulating resin. The conductive thermoplastic resin is wrapped, and a controller passes a current through the conductive thermoplastic resin to supply a certain amount of energy, thereby melting the conductive thermoplastic resin and fusing the surface of the pipe inserted in advance, making it possible to easily connect the conductive thermoplastic resin.

According to the third aspect of the present invention, the heating element and the fused portion are made of a conductive thermoplastic resin made of conductive filler such as carbon black, metal powder, or carbon fiber, and are formed into a spiral shape to provide heat directionality and prevent air from being entrained. This is a fusion joint that does not cause any damage to the fused portion.

According to a fourth aspect of the invention, an element is used that senses changes in the density or hardness of the material that is the heating element, and when the material softens, an electromechanical or electronic component is applied to detect and detect changes in the properties of the material. It is possible to use this to inform the melting current interrupt system.

[Example] The first method of the present invention will be further described below with reference to the accompanying drawings.

FIG. 1 shows a fusion joint made of medium-density polyethylene resin in which carbon black, which is a conductive filler, is blended according to the present invention. The physical properties of typical conductive carbon flanks are shown in Table 1 Table 1 Physical properties It is important to create a uniform compound without any unevenness and to suppress the increase in viscosity due to the structural viscosity of carbon.

In Figures 2 and 3, conductive thermoplastic resin 2 or 2I is formed by mixing aluminum metal powder with medium density polyethylene resin, and then thermoplastic insulating resin 1 or 11 is added to the medium density polyethylene resin on the outer periphery. It is a fusion joint made by molding. Table 2 shows the relationship between the mixing ratio of half of the aluminum metal and polyethylene and the electrical resistance.

Table 2 Mixing ratio of filler and electrical resistance Determined according to the application, taking into consideration the mechanical performance and fluidity deterioration of the resin. FIG. 5 shows the fusion joint of FIG. 3 inserted into the pipe 4 of FIG. 4. Convex connector bushing 3
1. Connect a controller to 32 and turn on electricity so that the conductive thermoplastic resin 21 generates heat and melts into the pipe 4 that is in contact with it.In this case, the pipe 4 and the thermoplastic insulating resin 11 are preferably made of the same resin. Desirable results were obtained when the matrix of No. 21 was made of the same resin.

FIG. 6 shows an example in which the conductive thermoplastic resin 21 shown in FIG. 5 has a spiral shape, and is obtained by molding polypropylene mixed with a stainless fiber filler, and is melted into the pipe 4. The cross-sectional shape changes sequentially in order to provide heat directivity that sequentially performs from one direction. Similarly, an embodiment is shown in which the cross section is shaped so that the heat generation and melting of the conductive thermoplastic resin and the pipe occur in a timely manner.

FIG. 7 shows a fusion joint in which a sensor connector bushing 71 is provided on the conductive thermoplastic resin 25 shown in FIG. It is possible to cope with non-uniform materials of the conductive thermoplastic resin 25 due to production or manufacturing.

[Effects of the Invention] As is clear from the above, according to the present invention, it is possible to easily manufacture a heating element with thermal directivity, and it is possible to prevent phenomena caused by air entrainment and to obtain a uniform fused portion. We provide fused joints with no residual stress, and it is also possible to control the fusion process.
Demonstrates excellent effectiveness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the socket joint of the present invention. FIGS. 2 and 3 are cross-sectional views of a socket joint whose inner surface and end surface are coated with conductive thermoplastic resin. FIG. 4 is a sectional view showing an example of a connecting pipe. FIG. 5 shows a sectional view of the pipe shown in FIG. 4 connected to the socket joint shown in FIG. 3. FIG. 6 is a diagram showing an example of the cross-sectional shape of conductive thermoplastic resin in a spiral shape. FIG. 7 shows a sectional view of the socket joint of FIG. 3 provided with a sensor recess. FIG. 8 shows a sectional view of a conventional socket joint. 1.11... Thermoplastic insulating resin, 2.21... Conductive thermoplastic resin, 31.32... Convex connector bush, 4... Connection pipe, 51.52... Thermoplastic insulation Resin, 55...Coil, 71...Sensor connector bushing. Figure 1 Figure 3 Figure 4 Figure Cross section of the spiral Figure Figure 4

Claims (1)

[Claims] 1) A fusion joint characterized by being made of a conductive thermoplastic resin containing carbon black, metal powder, metal fiber, or carbon fiber as a filler 2) Carbon black, metal powder, metal fiber, or carbon A fusion joint characterized in that a conductive thermoplastic resin containing fibers as a filler is provided at least on the end face or the inner surface.3) In claim 2, the conductivity of the conductive thermoplastic resin is 0.01. 4) A fusion joint according to claim 2, characterized in that terminals are provided at two locations on the conductive thermoplastic resin. 5) A fusion joint according to claim 2, characterized in that the conductive thermoplastic resin has a spiral shape. 6) A fusion joint according to claim 2, wherein the conductive thermoplastic resin has a spiral shape. A rubber holder that holds the sensor connector bush and thermocouple together in at least one place, and a rubber cap that holds the thermocouple lead wire and current-carrying cable. and a convex part or a concave part formed on the inner circumference of the rubber cap corresponding to the concave part or convex part, and the thermocouple and the lead wire, and the connector bush and the current-carrying cable are connected by connectors, respectively. A fusion joint characterized by being removably connected.