JPH04277473A - Water-tight processing method for joint of electric wires - Google Patents

Abstract

PURPOSE:To make enclosing of sufficient water-tightness with a lightweight single layer even at a divergent connection part of electric wires where a fillet processed corner exists, by putting a thermoplastic film over the connection part, and fusion attaching the film with a heat and air pressure given externally. CONSTITUTION:A thermoplastic film 1 is laid alongside the joint part of electric wires, and this part is surrounded by a pressure bearing case 4, and hot air 5 is sent by pressure into the case. Because the gap of film segments produced by folding is narrow and the inflowing encounters a considerable resistance, a pressure difference is generated between the inside and outside of the film, and thermally softened film segments one another and their contact surfaces with the joint part of wires are melted and sealed. The seal progresses from a wider portion of the gap to its narrower portion, and finally no air inflowing occurs any more from any part. Thus the water-tight processing for the joint part is completed. Accordingly the film 1 is fusion attached tightly even in case there is a fillet processed corner such as a divergent connection part of electric wires, which should achieve water-tightness in good workmanship.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for making electric wire connections watertight, and is particularly useful for making electric wire branch connections watertight.

0002

BACKGROUND OF THE INVENTION Watertight treatment is essential for electrical wire connections in order to guarantee insulation and prevent corrosion. Among the watertight treatment methods for electrical wire connections, there is a so-called method in which the electrical wire connections are wrapped with thermoplastic tape, and the tape wrap is heated and pressurized in a mold to heat-seal the tape layers. Since the tape-wrapped mold method uses a heat-fusion method, it has excellent watertightness and requires simpler equipment than the cast mold method.

[0003] When this tape winding mold method is used for wire branch connections, depending on the form of the branch connection, a cavity may be formed inside the tape winding, and it is necessary to use metal to crush this cavity. Since mold pressure must be high, there is a risk of wire breakage in the case of thin wires. Further, for a branch connection, the amount of material used for the surface area of the wire connection is larger than that for a straight connection, and the weight of the connection becomes large. Therefore,
For connections with relatively thin wires, such as automobile wires, which also require vibration prevention and weight reduction,
It is not appropriate to use the tape-wrapped mold method described above.

0004

[Problem to be Solved by the Invention] Conventionally, as a method for insulating branch connections of relatively thin electric wires, the method shown in FIG.
As shown in (B) (a cross-sectional view of FIG. 2), a heat-shrinkable insulating film 1' is vertically attached on the branch connection part, and both width ends 11', 11' of this longitudinally attached film 1' are Also, both lengthwise ends 12', 12' are bonded to the outer surface of the electric wire with adhesive 2', and the intermediate portion 10' of the film between the main line and the branch line is bonded with adhesive 2', and then,
A method of heating and shrinking a longitudinally attached heat-shrinkable film is known, but in this method, the film intermediate portion 1 of the conduit
0' is also pulled due to contraction, and due to this tensile force, the location P' between the film intermediate portion 10' and the surface of the electric wire is likely to expand, causing a problem in watertightness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a watertight treatment method for electrical wire connections that can coat the electrical wire connections with an insulating film in a lightweight single layer with sufficient watertightness.

[0006]

[Means for Solving the Problems] The method of making the electric wire connection part watertight according to the present invention covers the electric wire connection part with a thermoplastic film, and applies heat and air pressure to the electric wire connection part from the outside. or by coating a thermoplastic film on the wire connection portion, and removing air from the end of at least one electric wire opposite to the wire connection portion side end;
This structure is characterized in that the thermoplastic film is fused onto the wire connection portion by applying heat and air pressure from the outside.

[0007]

[Operation] The thermoplastic film coated on the wire connection portion is heated while being subjected to air pressure, and due to this pressurizing force and thermal softening of the thermoplastic film, the wire connection portion is tightly fused onto the wire connection portion. In this case, since air is pressurized, it is possible to pressurize the inner corners of the outer surface of the thermoplastic film, and watertightness can be sufficiently ensured even at the wire branch connection portion.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. In order to make the electric wire connection part watertight according to the present invention, (A) and (B) in FIG. 1 [Ro-Ro cross section in FIG. As shown in the figure, a thermoplastic film 1 is bent at the center 10 and attached vertically to the connection part of the electric wire (usually 5 cm2 or less), especially the branch connection part, and an adhesive 2 ( Partial painting is also possible) or bind with clips, etc. This binding is for temporarily fixing the thermoplastic film to the wire connection portion, and gaps exist between the folded films and at the edges.

[0009] After the thermoplastic film is vertically attached to the electric wire connection part, as shown in (d) of FIG.
Heated air 5 is pressurized into the tank 4.

[0010] In this case, the gap between the folded thermoplastic film 1 is narrow, and considerable resistance acts on the inflow of pressurized air into this gap, so a pressure difference is created between the inside and outside of the thermoplastic film 1. , a state in which the internal pressure becomes lower than the external pressure occurs transiently, and the contact surfaces of the heat-softened thermoplastic films 1 and 1 as well as the contact surface between the film 1 and the wire connection portion are fused and sealed. Ru. In this sealing process, the wider the gap inside the thermoplastic film that covers the wire connection, the greater the airflow and the lower pressure, so the film first deforms and contacts in that area, and Accordingly, the inflow of air decreases. As a result, next
Another part of the film with a large flow rate is deformed, and the seal progresses from the part with a wide gap to the part with a narrow gap.
Eventually, air no longer flows in from any part of the body,
Watertight treatment of electric wire connections is completed.

[0011] Instead of press-fitting heated air as described above, it is also possible to generate a differential pressure by removing the air inside the thermoplastic film vertically attached to the wire connection part. Blowing hot air onto the outer surface, radiant heating using an infrared heater, etc. can be used. To bleed the air, insert an air bleed tube inside the thermoplastic film attached vertically to the wire connection, and bleed the air from this tube. A method can be used in which air is vented from the opposite end using the gap between the stranded conductors of the wire as an air vent passage.

[0012] In the above, since the thermoplastic film is pressurized by air pressure in a heat-softened state, it easily adapts to and is fused to the electrical wire connection portion, which is the surface to be sealed, even if the applied pressure is low. .

The watertightness of the wire joint treated according to the present invention depends on the flow of the heat-softened thermoplastic material into the gap in the wire joint. It is necessary for the thermoplastic film to have a viscosity that allows it to flow into the gap, and the softening temperature of the thermoplastic film,
The thickness etc. are selected depending on the temperature, differential pressure, etc. to be applied. The thickness of the thermoplastic film is usually 10 μm to 5 m.
selected from within the range of m. The heating temperature of the air is approximately 80
C., and in this case, the thermoplastic film used has a softening temperature of 100.degree. C. or higher.

[0014] In the method of making a wire joint watertight according to the present invention, it is advantageous to reduce the thickness of the thermoplastic film in order to reduce the weight of the treated wire joint. In this case, the thermoplastic film is a laminate of two types of films with different softening temperatures.
If the film layer is used facing outward (at least 5℃, preferably 10℃ or more), even if the overall thickness of the film is reduced, it is possible to prevent holes from forming in the thermoplastic film due to the above differential pressure, making it safe. be.

It is also possible to use a laminated film of a thermoplastic film and a film made of a material that does not flow even when softened, with the former film layer facing outward. Alternatively, a laminated film of a thermoplastic film and a thermosetting film may be used with the thermosetting film layer facing outward.

[0016] It is also possible to provide an adhesive layer on one side of the thermoplastic film or laminated film and attach the film vertically to the wire connection portion with the adhesive surface facing inward. A hot melt type adhesive layer may be used for this adhesive layer. In the above, a heat shrinkable film can also be used as the thermoplastic film.

[0017]

[Effects of the Invention] The method for making a wire connection part watertight according to the present invention has the above-mentioned structure, and the thermoplastic film coated on the wire connection part is pressurized by an air differential pressure and is thermally softened. Even if there is a corner, such as a wire branch connection, the thermoplastic film can be closely fused to the corner due to air pressure, making it possible to achieve good watertightness. In addition, when it is placed vertically on the wire connection part, it can be treated with a single layer of insulating film, and weight reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, in which (A) is a side view of a stage in which a thermoplastic film is longitudinally applied and covered;
B) shows a cross-sectional view of the roller in Figure A, (C) shows a cross-sectional view of the same in Figure A, and (D) shows the pressurizing/heating stage.

FIG. 2 is an explanatory side view (A) showing a conventional example and a sectional view taken along the roller in FIG.

[Explanation of symbols]

1 Thermoplastic film 4 Pressure resistant case 5 Heated air

Claims (6)

[Claims] 1. Watertightness of an electric wire connection, characterized by coating the electric wire connection with a thermoplastic film, and applying heat and air pressure from the outside to fuse the film onto the electric wire connection. Processing method. 2. A thermoplastic film is coated on a wire connection portion, and the thermoplastic film is heated from the outside while air is removed from an end of at least one wire opposite to the end on the wire connection portion side. 1. A watertight treatment method for an electric wire joint, characterized in that the electric wire joint is fused onto the electric wire joint by applying air pressure and air pressure. 3. A method for making a wire connection part watertight according to claim 1 or claim 2, using a laminated film in which two types of thermoplastic films are bonded to a thermoplastic film. 4. A method for making a wire connection part watertight according to claim 1 or claim 2, wherein the thermoplastic film is a single-sided adhesive thermoplastic film having an adhesive layer on the inner surface. 5. A method for making a wire connection part watertight according to claim 3, wherein the softening temperature of the outer layer of the laminated film is higher than the softening temperature of the inner layer by 5° C. or more. 6. A method for making a wire connection part watertight according to claim 4, wherein a hot melt type adhesive is used in the adhesive layer of the single-sided adhesive thermoplastic film.