JP2007052999A - Water cut-off method of electric wire and electric wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To waterproof a bare conductor by simple equipment in an grounding electric wire applied to a wire-harness for a vehicle or the like. <P>SOLUTION: A die 5 is installed so as to surround a bare conductor 1a of the grounding electric wire 1, and urethane foam is injected into the die 5. The urethane foam is foamed in the die 5 and a molded product is extracted from the die 5. In this case, a product of a natural foaming ratio of urethane foam and an injected volume is to exceed a cavity volume of the die 5. Thereby, the urethane foam is foamed in the die 5 and internal pressure is generated such that the urethane foam penetrates into the detailed part of the bare conductor 1a of the grounding electric wire 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric wire water stopping method and an electric wire suitable for application to a wire harness for a vehicle and the like.

  FIG. 10 is a plan view showing an example of a conventional grounding wire.

  Generally, this type of grounding wire is connected to an appropriate grounding part (for example, the body of a vehicle) with a grounding connection terminal fixed to the terminal thereof exposed to the outside. For this reason, moisture easily enters from the end of the ground wire through the inside of the wire coating. Therefore, when there is an electronic control unit at the terminal opposite to the ground connection terminal, there is a possibility that moisture reaches the electronic control unit and prevents normal operation. Therefore, it is necessary to perform a water stop treatment on the grounding wire.

Conventionally, as such a water stopping method, as shown in FIG. 10, there is a method in which the connecting portion between the ground wire 1 and the ground connection terminal 2 is covered with a mold resin 4 such as a hot melt adhesive to stop the water. It has been proposed (see, for example, Patent Document 1).
JP 2001-162646 A

  However, in this conventional method, in addition to a heating device for maintaining the mold resin 4 in a molten state in order to ensure the fluidity of the mold resin 4 and an injection facility for spreading the mold resin 4 into a predetermined shape, There is a disadvantage that a large-scale facility such as a mold facility that maintains a matching pressure that does not open is required.

  Such a situation is the same for the wires other than the ground wire.

  An object of this invention is to provide the water-stopping method and electric wire of an electric wire which can eliminate such an inconvenience.

First of all, the invention of the water stopping method for an electric wire according to claim 1 is a mold attaching step in which a die is attached so as to surround a bare wire conductor of the electric wire, and a foam material injection in which a foam material is injected into the die. A foaming step in which the foamed material is foamed in the mold to mold a molded product, and a mold removing step in which the molded product is removed from the mold.
Moreover, the invention of the water stopping method for electric wires according to claim 2 is characterized in that the product of the natural foaming rate and the injection amount of the foamed material exceeds the cavity volume of the mold.
The electric wire waterproofing method according to claim 3 is characterized in that the foamed material is urethane foam.
The invention of the electric wire according to claim 4 is characterized in that the electric wire is stopped by the electric water stopping method according to any one of claims 1 to 3.

  ADVANTAGE OF THE INVENTION According to this invention, the bare wire conductor of electric wires, such as an earth | ground electric wire, can be water-stopped with the simple installation only of a metal mold | die.

  When the product of the natural foaming rate and the injection amount of the foam material exceeds the cavity volume of the mold, the foam material foams in the mold and an internal pressure is generated. Therefore, the foamed material can penetrate into the details of the bare wire conductor and the electric wire can be surely stopped.

  Furthermore, when urethane foam is used, the shape stability at a high temperature of 100 ° C. or higher is excellent, so that the use of electric wires is expanded.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing a first embodiment of a grounding wire according to the present invention. FIG. 2 is a front view showing a mold attaching step in one embodiment of a water stopping method for a grounding wire according to the present invention. 3 is a front view showing a foaming material injection step in one embodiment of the water stopping method for the grounding electric wire according to the present invention, and FIG. 4 shows a foaming step in one embodiment of the water stopping method for the grounding electric wire according to the present invention. It is a front view.

  As shown in FIG. 1, a ground connection terminal 2 is fixed to the end of the grounding wire 1, and a molded product 3 made of urethane foam is connected to both ends of the grounding wire 1. It is molded so as to cover the conductor 1a.

  And when stopping the terminal of this earthing | grounding electric wire 1, ie, the connection part with the earthing connection terminal 2, it follows the following procedure.

  First, as shown in FIG. 2, a mold 5 having a predetermined cavity volume (for example, 1.0 ml, 1.2 ml, 1.8 ml, etc.) is prepared, and this mold 5 is used as the terminal of the grounding wire 1. Install. At this time, the bare wire conductor 1 a at the end of the ground wire 1 is surrounded by the mold 5.

  Next, as shown in FIG. 3, a two-component mixed urethane foam having a natural foaming rate of 2 to 4 times is injected into the mold 5. At this time, the urethane foam is set so that the product of the natural foaming rate and the injection amount exceeds the cavity volume of the mold 5. For example, when using a mold 5 with a cavity volume of 1.2 ml, when using foamed urethane with a natural foaming rate of 2 times, increase the injection volume from 0.6 ml and use foamed urethane with a natural foaming rate of 3 times. When the foaming urethane is used, the injection amount is made larger than 0.4 ml, and when the urethane foam having a natural foaming ratio of 4 times is used, the injection amount is made larger than 0.3 ml. Also, when using a mold 5 with a cavity volume of 1.8 ml, when using foamed urethane with a natural foaming rate of 2 times, the amount of injection is greater than 0.9 ml, and foamed urethane with a natural foaming rate of 3 times is used. When the foaming urethane is used, the injection amount is made larger than 0.6 ml. When the urethane foam having a natural foaming ratio of 4 times is used, the injection amount is made larger than 0.45 ml.

  Next, as shown in FIG. 4, the injection port 5a of the mold 5 is closed and left for a predetermined time. Then, the urethane foam expands while expanding in the mold 5. At this time, since the product of the natural foaming rate and the injection amount of the urethane foam exceeds the cavity volume of the mold 5, the urethane foam tries to expand further after filling the mold 5 without gaps. However, since the expansion of the urethane foam is suppressed by the mold 5, an internal pressure is generated in the mold 5, and the urethane foam penetrates into the part to be molded, that is, the details of the bare wire conductor 1 a of the ground wire 1. The molded product 3 is molded in the form.

  Then, when the foaming reaction of the urethane foam is completed after a predetermined time has elapsed, the molded product 3 is taken out from the mold 5 as shown in FIG. Then, the end of the ground wire 1 is in a state of being stopped by foamed urethane. At this time, since the urethane foam penetrates into the details of the bare wire conductor 1a of the grounding wire 1, the terminal of the grounding wire 1 can be surely stopped.

  Here, the water stop operation of the terminal of the grounding wire 1 is completed.

  In this way, the terminal of the grounding wire 1 can be stopped with a simple facility using only the mold 5. In addition, urethane foam is superior in shape stability at a high temperature of 100 ° C. or higher as compared with a hot melt adhesive used as a conventional mold resin. Therefore, the applicable range of the grounding electric wire 1 that has stopped in this way is expanded to applications that are used at high temperatures.

  In the above-described embodiment, the case where the bare wire conductor 1a at the terminal of the grounding wire 1 is stopped is described. However, as shown in FIG. The water can be stopped. In this case, since the structure of the mold 5 is not restricted by the shape of the ground connection terminal 2, the versatility of the mold 5 is improved.

  In the above-described embodiment, the case where the single crimping type grounding wire 1 is stopped is described. However, as shown in FIG. 6, the terminal of the double crimping type grounding wire 1 is stopped at one place. You can also Further, as shown in FIG. 7, the bare wire conductors 1b at the two stripped portions of the double crimping type grounding wire 1 can be separately stopped. Furthermore, as shown in FIG. 8, the bare wire conductors 1 b at the two stripped portions of the double crimp type grounding wire 1 can be collectively stopped at one place. In these cases, since the structure of the mold 5 is not restricted by the shape of the ground connection terminal 2, the versatility of the mold 5 is improved.

  In the above-described embodiment, the case where a two-component mixed urethane foam having a natural foaming ratio of 2 to 4 times is used as the foaming material has been described. However, as long as the natural foaming ratio is more than 1 time, urethane foam other than the two-component mixed type can be used. Further, depending on the use of the grounding electric wire 1, it is possible to substitute a foam material other than urethane foam (for example, polystyrene, polyethylene, polypropylene, silicone, etc.).

  In addition, in the above-mentioned embodiment, although the electric wire 1 for earth | ground was demonstrated, this invention can be widely applied not only to the electric wire 1 for earth | ground but to the electric wire of other uses.

  Examples of the present invention will be described below.

  With respect to a grounding terminal in which two wires having a conductor cross-sectional area of 1.25 mm 2 were double-bonded, 0.7 g of urethane foam having a natural foaming ratio of 3 times was injected into a mold having a cavity volume of 1.0 ml. Here, the method of aligning the dies was a clip.

  As a result, in the initial stage, the water-stopping property of 200 kPa (about 2 kgf / cm 2) or more was exhibited, and the water-stopping property of 200 kPa was maintained even after being left at a temperature of 110 ° C. for 200 hours. And when it was confirmed how much foaming urethane has penetrated into the electric wire, the penetration distance in the core wire was about 3 mm. The actual foaming ratio of the urethane foam was 1.75 times.

  As the amount of urethane foam injected increases, the penetration distance into the core wire is expected to increase. Therefore, two types of wires with conductor cross-sectional areas of 1.25 mm2 and 0.5 mm2 are naturally placed in a mold with a cavity volume of 1.0 ml. 0.5 g, 0.6 g, 0.7 g, and 0.8 g of urethane foam having a foaming rate of 3 times were injected, and the penetration distance in each core wire was measured. The results are summarized and shown in a graph in FIG. In FIG. 9, “CAVS 1.25 sq” represents an electric wire having a conductor cross-sectional area of 1.25 mm 2, and “CAVS 0.5 sq” represents an electric wire having a conductor cross-sectional area of 0.5 mm 2.

  As is clear from the graph shown in FIG. 9, for any of the electric wires, it was confirmed that the penetration distance in the core wire increased as the amount of urethane foam injected increased. This is presumably because the initial occupation ratio with respect to the cavity volume of the mold increases as the amount of urethane foam injected increases, and as a result, the internal pressure after foaming increases.

  The present invention can be widely applied to wire harnesses for vehicles.

It is a top view showing a 1st embodiment of an electric wire for grounding concerning the present invention. It is a front view which shows the metal mold | die attachment process in one Embodiment of the water stop method of the earth | ground electric wire which concerns on this invention. It is a front view which shows the foaming material injection | pouring process in one Embodiment of the water stop method of the earth | ground electric wire which concerns on this invention. It is a front view which shows the foaming process in one Embodiment of the water stop method of the electric wire for earth | grounds concerning this invention. It is a top view which shows 2nd Embodiment of the electric wire for earthing | grounding which concerns on this invention. It is a top view which shows 3rd Embodiment of the electric wire for earthing | grounding which concerns on this invention. It is a top view which shows 4th Embodiment of the electric wire for earthing | grounding which concerns on this invention. It is a top view which shows 5th Embodiment of the electric wire for earthing | grounding which concerns on this invention. It is a graph which shows the relationship between the injection amount of urethane foam, and the penetration distance in a core wire. It is a top view which shows an example of the conventional electric wire for earthing | grounding.

Explanation of symbols

1 ... Earth wire (wire)
1a, 1b ... Bare wire conductor 2 ... Ground connection terminal 3 ... Molded product 5 ... Mold

Claims (4)

A mold attaching process in which a mold is attached so as to surround the bare conductor of the electric wire;
A foam material injection step in which the foam material is injected into the mold;
A foaming process in which the foam material is foamed in the mold to mold a molded product;
A mold water-stopping method, comprising: a mold removing step in which the mold product is removed from the mold.   The method for water-stopping an electric wire according to claim 1, wherein a product of a natural foaming rate and an injection amount of the foamed material exceeds a cavity volume of the mold.   The method for water-stopping an electric wire according to claim 1, wherein the foam material is urethane foam.   An electric wire that is water-stopped by the method for water-stopping an electric wire according to any one of claims 1 to 3.

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