WO2009011182A1

WO2009011182A1 - Electrical wire coating apparatus and method thereof

Info

Publication number: WO2009011182A1
Application number: PCT/JP2008/060405
Authority: WO
Inventors: Moriatsu Taniguchi; Takeshi Kamata; Keigo Sugimura
Original assignee: Yazaki Corporation
Priority date: 2007-07-17
Filing date: 2008-05-30
Publication date: 2009-01-22
Also published as: JP2009026475A; JP5160824B2; CN101743600B; CN101743600A; PT2009011182W

Abstract

An electrical wire coating apparatus forms a coating layer on an outer surface of an electrical wire. The electrical wire coating apparatus has a coating material for forming the coating layer, a pair of sponges that is elastic and configured to be impregnated with a coating liquid made of a coating material and a solvent in which the coating material is dissolved, an accommodating tub that accommodates the pair of the sponges, a moving unit that holds the electrical wire and moves the electrical wire and the accommodating tub relative to each other in a direction orthogonal to a longitudinal direction of the electrical wire, and a pair of indentations that allows the electrical wire moving relative to the accommodating tub to be accommodated into the accommodating tub.

Description

DESCRIPTION

ELECTRICAL WIRE COATING APPARATUS AND METHOD THEREOF

TECHNICAL FIELD

The present invention relates to an electrical wire coating apparatus and method thereof for providing a coating layer on an outer surface of an electrical wire.

RELATED ART As an automobile as a movable body incorporates increasing number of electronic devices, numerous wiring harnesses are used to deliver power supplied from a power source and to transmit control signals from an electronic control unit and on-vehicle microcontrollers and microprocessors to the electronic devices. The wiring harness includes an electrical wire and a connector attached to a terminal of the electrical wire. The electrical wire is a coated electrical wire that has an electrically conductive core wire and an electrically insulating synthetic resin covering the core wire. The connector has an electrically conductive terminal fitting and an electrically insulating connector housing. The terminal fitting is attached to the terminal of the electrical wire to electrically connect the terminal to the core wire of the electrical wire. The connector housing is box-shaped and configured to accommodate the terminal fitting into a terminal accommodating chamber in a shape of a straight-hole formed inside of the connector housing.

When assembling the wiring harness, the electrical wire is cut in a predetermined length, and then the terminal fitting is attached to a terminal of the electrical wire, and the electrical wires are connected to each other as required. Thereafter, the terminal is inserted into the connector housing. In this way or in a similar manner, the wiring harness is assembled.

The terminal of the electrical wire of the wiring harness has, a marking (formed by applying a coloring material to the outer surface of the electrical wire) that provides operation instruction information including correspondence between the terminal and a connector housing (of the terminal accommodating chamber) into which the terminal should be inserted, (see Patent Document 1). Since such markings may be degraded over time or eventually lost, the coloring material is protected against coming off the outer surface of the electrical wire by first applying an undercoating material on the surface of the electrical wire so as to form a coating layer, and then further applying the coloring material upon the coating layer, so that adhesion of the coloring material can be improved.

As described in the foregoing, when the marking is only provided on the terminal of the electrical wire, the coating layer only has to be formed on the terminal using the aforementioned coating material. A coating method used in such a case is, for example, so-called dip coating that forms the coating layer by immersing the electrical wire held in a vertical direction in a coating liquid made of the coating material and a solvent used to solve the coating material.

Patent Document 1: Japanese Patent Application Laid-Open Publication No.

H05-217435

DICLOSURE OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

However, as mentioned above, when the electrical wire is held in the vertical direction and the terminal of the electrical wire is immersed in the coating liquid, the coating liquid may enter a gap between the core wire and the cover portion of the electrical wire and reach the core wire. As a result, mechanical characteristics and electrical conductivity of the electrical wire may be adversely affected.

The present invention aims to solve the above identified problems. It is and object of the present invention to provide an electrical wire coating apparatus and method thereof for forming the coating layer only on the cover portion of the electrical wire, while effectively preventing the degradation of the mechanical characteristics and the electrical conductivity of the electrical wire.

MEANS FOR SOLVING THE PROBLEM

In order to solve the above identified problems, the present invention according to a first aspect of the present invention is to provide an electrical wire coating apparatus for forming a coating layer on an outer surface of an electrical wire that includes an elastic porous member that is impregnated with a coating liquid for forming the coating layer, the coating liquid being made of a coating material and a solvent in which the coating material is dissolved; an accommodating tub that receives the porous member; a moving unit that holds the electrical wire and causes the electrical wire to move close to and away from the accommodating tub in a direction orthogonal to a longitudinal direction of the electrical wire; and an electrical wire receiving part that allows the electrical wire moving close to and away from the accommodating tub to be accommodated in the accommodating tub. According to a second aspect of the present invention, the electrical wire coating apparatus according to the first aspect of the present invention is provided with the porous member that has a groove configured to pass therethrough the electrical wire that is received in the electrical wire receiving part.

According to a third aspect of the present invention, the wire coating apparatus according to the second aspect of the present invention has a plurality of recesses that are formed on an inner surface of the groove. According to a fourth aspect of the present invention, the electrical wire coating apparatus according to the second or third aspect of the present invention has a second porous member provided at a portion of the electrical wire receiving part corresponding to each of both ends in the longitudinal direction of the electrical wire. The second porous member is elastic and configured to elastically deform so as to communicate with the groove. The second porous member also has a slit that allows the electrical wire to pass therethrough when the electrical wire is accommodated in the electrical wire receiving part. The slit is resiliently restored and closed when the electrical wire is positioned outside of the electrical wire receiving part. According to a fifth aspect of the present invention, the electrical wire coating apparatus according to either of the first to fourth aspect of the present invention has a supply unit that supplies the porous member with the coating liquid.

An electrical wire coating method according to a sixth aspect of the present invention forms the coating layer on the outer surface of the electrical wire by (a) moving the electrical wire relative to the accommodating tub that accommodates the elastic porous member impregnated with the coating liquid for forming the coating layer, the coating liquid made of the coating material and the solvent in which the coating material is dissolved; and (b) forming the coating layer on the outer surface of the electrical wire by placing the electrical wire in and out of the accommodating tub.

EFFECTS OF THE INVENTION

According to the first aspect of the present invention, the electrical wire coating apparatus is provided with the elastic porous member that is impregnated with the coating liquid for forming the coating layer, the coating liquid being made of the coating material and the solvent in which the coating material is dissolved; the accommodating tub that receives the porous member; the moving unit that holds the electrical wire and moves the electrical wire relative to the accommodating tub in the direction orthogonal to the longitudinal direction of the electrical wire; and the electrical wire receiving part that allows the electrical wire moving relative to the accommodating tub to be accommodated in the accommodating tub. By virtue of this construction and arrangement, it is possible to form the coating layer by accommodating a desired portion of the electrical wire in its longitudinal direction into the accommodating tub, and letting the desired portion contact the pair of sponges. It is possible to prevent the coating agent from adhering to a tip of the electrical wire while the coating layer can be formed on a cover portion of the electrical wire only, and thus degradation of mechanical characteristics and electrical conductivity of the electrical wire can be effectively prevented.

According to the second aspect of the present invention, since the porous member has the groove configured to pass the electrical wire accommodated in the electrical wire receiving part, the electrical wire can be passed through the groove of the porous member and positioned inside of the porous member, and thus the electrical wire can be accurately positioned inside of the porous member.

According to the third aspect of the present invention, the recesses provided on the inner surface of the groove allows the excessive coating liquid applied to the outer surface of the electrical wire to flow into the recesses, thus allowing an amount of the coating liquid used to be reduced, and uniformly forming the coating layer on the outer surface of the electrical wire.

According to the fourth aspect of the present invention, the second porous member is provided at each of the portions of the electrical wire receiving part corresponding to both ends on the longitudinal direction of the electrical wire. The second porous member is elastic and has a slit configured to elastically deform, communicate with the groove so as to allow passage of the electrical wire when the electrical wire is being accommodated in the electrical wire receiving part, and close when the electrical wire is positioned outside of the electrical wire receiving part. The coating liquid impregnating the porous member is prevented from spilling out of the electrical wire receiving part to an outside of the accommodating tub. According to the fifth aspect of the present invention, the supply unit that supplies the porous member with the coating liquid allows automatic supply of the coating liquid to the porous member, thus improving the operating efficiency.

According to the sixth aspect of the present invention, the coating layer is formed on the outer surface of the electrical wire by (a) moving the electrical wire relative to the accommodating tub that accommodates the elastic porous member impregnated with the coating liquid for forming the coating layer, the coating liquid made of the coating material and the solvent in which the coating material is dissolved; and (b) forming the coating layer on the outer surface of the electrical wire by placing the electrical wire in and out of the accommodating tub. By virtue of this process, it is possible to form the coating layer by accommodating the desired portion of the electrical wire in its longitudinal direction into the accommodating tub, and letting the desired portion contact the pair of sponges. It is possible to prevent the coating agent from adhering to the tip of the electrical wire while the coating layer can be formed on the cover portion of the electrical wire only, and thus degradation of mechanical characteristics and electrical conductivity of the electrical wire can be effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view of the electrical wire coating apparatus according to one embodiment of the present invention. FIG. 2 is a perspective view of an electrical wire with a coating layer formed by the electrical wire coating apparatus of the present invention. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2.

FIG. 4 is a front view of the electrical wire coating apparatus of FIG. 1.

FIG. 5 is a front view illustrating the wire of FIG. 4 accommodated in an accommodating tub. FIG. 6 is a cross-sectional view of the electrical wire coating apparatus of FIG. 5 taken along a line in a vertical direction of FIG. 5.

FIG. 7 is a top view of the electrical wire coating apparatus of FIG. 5.

FIG. 8 is a fragmentary perspective view of the electrical wire coating apparatus according to the embodiment of the present invention.

REFERENCE SIGNS 1 : Electrical wire coating apparatus

2: Electrical wire

3 : A pair of sponges (porous members) 4: Accommodating tub

5: Moving unit

6: Indentation (electrical wire receiving part)

7: Supply unit

22a: Outer surface 23: Coating layer 32: Groove 32a: Inner surface 33: Recess

43 : Second sponge (second porous member) 45: Slit DESCRIPTION OF THE PREFERRED EMBODIMENT

An electrical wire coating apparatus according to one embodiment of the present invention is described with reference to FIGS. 1 to 7. The electrical wire coating apparatus 1 according to the one embodiment of the present invention is configured to form a coating layer 23 upon an outer surface 22a of an electrical wire 2.

Referring to FIG. 1, the electrical wire coating apparatus 1 has a pair of elastic sponges 3, i.e., porous members according to the present invention, which is impregnated with a coating liquid made of a coating material and a solvent in which the coating material is dissolved, an accommodating tub 4 configured to accommodate the pair of sponges 3, a moving unit 5 that holds the electrical wire 2 and makes the electrical wire 2 and the accommodating tub 4 move close to and away from each other in a direction orthogonal to a longitudinal direction of the electrical wire 2, an indentation 6 (which is an electrical wire receiving part according to the present invention) that allows the electrical wire 2 moving relative to the accommodating tub 4 to be accommodated in the accommodating tub 4, and a supply unit 7 (see for example FIG. 4) that supplies the coating liquid for the pair of sponges 3.

Referring to FIGS. 2 and 3, the electrical wire 2 is part of a wiring harness for an automobile as a movable body. The electrical wire 2 has an electrically conductive core wire 21 and an electrically insulating cover portion 22. The core wire 21 is made of a plurality of twisted single wires. The twisted wires of the core wire 21 are made of an electrically conductive metallic material. The core wire 21 may consist of one single wire.

The cover portion 22 is made of for example a synthetic resin such as a polyvinylchloride (PVC). The cover portion 22 covers the core wire 21. The electrical wire 2 including the core wire 21 and the cover portion 22 has a circular cross section. The electrical wire coating apparatus 1 according to this embodiment is configured to form the coating layer 23 on the outer surface 22a of the electrical wire 2, or, to be more specific, on the outer surface 22a of the cover portion 22.

The coating layer 23 is made of for example a methacrylic resin and acrylic resin as a coating material, hi the illustrated example, the coating material is polymethylmethacrylate (PMMA). The term "methacrylic resin" used in this specification denotes a resin obtained by copolymerizing methacrylic acid or methacrylate ester. Also, the term "acrylic resin" used in this specification denotes a resin obtained by copolymerizing acrylic acid or acryl ester.

Particularly, methyl methacrylate polymer is a plastic material best suited considering its transparency and weatherability, and therefore widely used in various industrial components for building construction, illumination, signboards, and sundries.

In addition, various methacrylate esters, for example, ethyl methacrylate, n-butyl, iso-butyl, hexanitrodiphenyl-amine, and lauryl are increasingly used in paint, adhesives, textile, leather and for finishing of paper. In addition, copolymerizing methacrylate and introducing a carboxyl group to a polymer is a widely used technique that ensures improved adhesiveness along with other properties such as water solubility and cross-linking performance.

The coating layer 23 made of such a material as described above covers an entire periphery of the cover portion 22 of the electrical wire 2. The coating layer 23 is formed on one end 2a except for a tip 2b of the electrical wire 2. A thickness T of the coating layer 23 is uniform ranging from approximately 50 μm to 200 μm. Thus, a cross section of the electrical wire 2 and coating layer 23 formed on the outer surface 22a of the cover portion 22 of the electrical wire 2 is in a shape of a circle.

The outer surface 23a of the coating layer 23 with the above-described composition is colored with a coloring material. The coloring material is securely applied to and retained by the outer surface 23a of the coating layer 23 by virtue of the coating layer 23. The coloring material of this kind can be used to provide operation instruction information. The operation instruction information includes for example information on correspondence between the terminal and a connector housing (of a terminal accommodating chamber) into which the terminal should be inserted. The coloring material is a liquid material made of the coloring material (organic substance for industrial use) dissolved or dispersed in water or other solvent. As the organic substance, dye and pigment are widely used (most of which is an organic substance and compound). The dye may mean the pigment and vice versa is possible depending on a terminology. To be more specific, the term "coloring material" used in this specification may denote both of a coloring liquid and the paint.

The term "coloring liquid" above denotes a liquid made of a solvent in which the dye is dissolved or dispersed. The term "paint" is a liquid made of the pigment and a dispersion liquid in which the pigment is dispersed. Consequently, when the electrical wire 2 having coating layer 23 is colored with the coloring liquid, the coating layer 23 is soaked with the dye. Meanwhile, when the electrical wire 2 having the coating layer 23 is colored with the paint, the paint is applied to the coating layer 23 without an inside of the coating layer 23 being soaked with the pigment.

It is also preferable that the solvent and the dispersion liquid have close affinity with the coating material that forms the coating layer 23. By virtue of the affinity, it is possible to ensure that the dye be applied to the inside of the coating layer 23 and the pigment be applied to the outer surface 23 a of the coating layer 23.

The coating liquid is made of the aforementioned coating material and a solvent in which the coating material is dissolved. As the solvent, one may use a well-known alcohol, polyhydric alcohol, ketone, or acrylate. It is preferable to use the solvent that evaporates at ambient temperature. In the shown example, the solvent is acetone as one example of ketone. The pair of sponges 3 are for example a porous material such as a synthetic sponge formed by foam molding of a plastic material such as polyurethane or a rubber. Numerous minute holes are formed inside of the sponge 3. When the sponge 3 is immersed in the coating liquid, air in the holes is replaced by the coating liquid and, as a result, an inside of the sponge 3 is impregnated with the coating liquid. The coating liquid can be easily removed by an external force. It is preferable to form the sponge 3 by a porous material having lower reactivity with the coating liquid.

Both of the pair of sponges 3 are rectangular-solid shaped. The pair of sponges 3 are disposed in the accommodating tub 4 such that a pair of indentations 6 (to be later described) of the accommodating tub 4 are provided between the pair of sponges 3. Each of the sponges 3 has a size that allows elastic deformation and accommodation in the accommodating tub 4, and is configured to pass the electrical wire 2 through an area between each other (a groove 32, which will be later described) when the electrical wire 2 is accommodated in the accommodating tub 4. The pair of sponges 3 has the groove 32 adapted to pass the electrical wire 2 to be accommodated in the pair of indentations 6. The groove 32, as has been explained above, is a space between the pair of sponges 3 disposed inside of the accommodating tub 4. The groove 32 is formed across an entire longitudinal direction of a bottom wall 41a of an accommodating tub body 41 (later described). Also, a width of the groove 32 is smaller than that of the electrical wire 2. It should be noted that the pair of sponges 3 may be replaced by one single sponge having the groove 32 formed at the center of the single sponge along a line that divides the single sponge into two pieces in the longitudinal direction of the bottom wall 41a.

As shown in FIGS. 5 to 7, the one end 2a of the electrical wire 2 is inserted into the groove 32 having the above-described configuration. The one end 2a of the electrical wire 2 is passed through the groove 32 by the moving unit 5, and causes the groove 32 to be elastically deformed as the one end 2a is in contact with an inner surface 32a of the groove 32 during to-and-fro movement of the one end 2a within the groove 32 (the inner surface 32a of the groove 32 in FIG. 7 is shown in a state prior to the above elastic deformation). When the groove 32 is elastically deformed, the coating agent impregnating the sponge 3 is discharged, and the coating agent retained by the sponge 3 is applied to the outer surface 22a of the electrical wire 2.

The inner surface 32a of the groove 32 has a plurality of recesses 33. The recesses 33 are indented in a direction orthogonal to the longitudinal direction of the groove 32. The plurality of the recesses 33 are spaced in parallel with respect to each other. An excessive coating liquid applied to the outer surface 22a of the electrical wire 2 flows into the recesses 33 as the end 2a of the electrical wire 2 is taken out of the groove 32, so that the excessive coating liquid is removed from the outer surface 22a of the electrical wire 2.

The accommodating tub 4 as shown in FIG. 6 has the accommodating tub body 41 in a cylindrical shape and mounting portions 42. The accommodating tub body 41 has the bottom wall 41a in a shape of a rectangular flat plate, a pair of sidewalls 41b upstanding from edges in the longitudinal direction of the bottom wall 41a, and the pair of second sidewall 41c upstanding from edges in a width direction of the bottom wall 41a and connecting to the pair of sidewalls 41b. The accommodating tub body 41 is open at its upper surface. The pair of the sidewalls 41b are spaced in parallel with respect to each other so as to face each other. Likewise, the pair of second sidewalls 41c are spaced in parallel with respect to each other so as to face each other. The sidewall 41b and the second sidewall 41c are orthogonal to each other. Each of the sidewalls 41b has the indentation 6. The indentation 6 will be later described in detail. The mounting portion 42, as illustrated in FIGS. 1 and 7, is formed along an entire inner periphery of each of the indentations 6. The mounting portion 42 has an orthogonal portion 42a that extends along the entire inner periphery of the indentation 6 and protrudes orthogonal to the sidewall 41b and toward both sides of the sidewall 41b, and a pair of edges 42b upstanding from the both ends in the width direction of the orthogonal portion 42a toward the inside of the indentation 6. The mounting portion 42 has a cross section in an U-shaped groove along the inner periphery of the indentation 6. A second sponge 43 (to be later described) is mounted inside of the groove-shaped mounting portion 42.

The moving unit 5, as illustrated in FIG. 1, has a clamping portion 51 as a retaining member that retains the electrical wire 2, a second retaining member 52 that retains the accommodating tub 4, and a driving mechanism (not shown). The clamping portion 51 sandwiches a portion 2c (hereafter called a "sandwiched portion") that is away from the tip 2b of the electrical wire 2 by so much as a length of the accommodating tub body 41 in the longitudinal direction in a manner that the one end 2a from the tip 2b to the sandwiched portion 2c is held horizontally. When the electrical wire 2 bends by a force of its own weight, making it difficult to keep horizontally the one end 2a of the electrical wire 2 using the clamping portion 51, a second clamping portion 51 may be provided to sandwich the tip 2b of the electrical wire 2.

The second retaining member 52 is formed for example in a shape of a flat plate, on an upper surface of which the accommodating tub 4 is secured. The second retaining member 52 is disposed at a lower side when viewed from the clamping portion 51. The second retaining member 52 as will be later described, is secured such that the one end 2a of the electrical wire 2 held by the clamping portion 51 can pass through the pair of indentations 6 of the accommodating tub 4 as when the second retaining member 52 is moved upward. The driving mechanism has for example an air cylinder having an extensible rod and a lever. The driving mechanism moves the second retaining member 52 toward the clamping portion 51 residing in an upper space when viewed from the second retaining member 52. This means that the driving mechanism causes the second retaining member 52 to move close to and away from the clamping portion 51. In other words, the driving mechanism causes the accommodating tub 4 to move close to and away from the electrical wire 2.

Referring to FIG. 1, teach of the indentations 6 are provided at the center in the width direction of each of the sidewalls 41b of the accommodating tub 4. The indentation 6 is formed by cutting the sidewall 41b in a straight line from an upper end of the sidewall 41b toward the bottom wall 41a, and the pair of indentations 6 are in parallel to each other. The pair of indentations 6 are arranged in a direction parallel to the second sidewall 41c. A groove 32 is on a straight line that connects one of the indentations 6 to the other. A width of the indentation 6 is larger than that of the electrical wire 2. The length of the indentation 6 is such that the deepest portion 6a, at which the indentation 6 is closest to the bottom wall 41a, remains lower than the upper surface 31 a of the sponge 3.

The electrical wire 2 is passed through each of the pair of indentations 6 with the above construction. Since the electrical wire 2 passes through both of the indentations 6, the electrical wire 2 can be located in the inside of the accommodating tub 4 while extending outside of the accommodating tub 4 via each of the indentations 6. Thus, the tip 2b of the electrical wire 2 is not disposed inside of the accommodating tub 4, and the coating agent is not applied to the tip 2b of the electrical wire 2.

The second sponge 43 (which is a second porous member) is provided at the pair of indentations 6 corresponding to the both ends of the electrical wire 2 in the longitudinal direction. The second sponge 43 is in a shape of a long prism, and made of the porous material so that the second sponge 43 can be impregnated with the coating liquid. Since the porous material is the same porous material as used in the sponge 3, detailed explanation is not provided here. The length of the second sponge 43 is about twice as large as that of the indentation 6. When inserting the second sponge 43 into pressing the mounting portion 42, the second sponge 43 is bent at the center in the longitudinal direction of the second sponge 43 so that the one end 43 a and the other end 43b in the longitudinal direction of the second sponge 43 are in contact with each other. Thus, the second sponge 43 is elastically deformed, inserted into the mounting portion 42, and elastically restored to be held in the mounting portion 42. Each of the second sponges 43 are disposed such that the indentation 6 is closed. The second sponge 43 has a slit 45. The slit 45 is created between the one end 43a and the other end 43b of the second sponge 43 that has been bent as described above. The slit 45 extends on an approximately entire length of the indentation 6 and in parallel to the indentation 6. When the electrical wire 2 is accommodated in the pair of indentations 6, the slit 45 is elastically deformed in the direction in which the one end 43 a and the other end 43 b of the second sponge 43 move away from each other, and the slit 45 communicates with the groove 32 so as to allow the electrical wire 2 to pass through the groove 32. In addition, when the electrical wire 2 is positioned outside of the pair of indentations 6, the second sponge 43 is elastically restored and the one end 43 a and the other end 43b of the second sponge 43 are brought into contact with each other and closed. The supply unit 7 supplies the coating liquid to the sponge 3 in the accommodating tub 4. The supply unit 7, as shown in FIG. 4, has a dispenser 71 and a barrel 72. One end of the barrel 72 is connected to the dispenser 71, and the other end of the barrel 72 is connected to the inside of the accommodating tub body 41. An inside of the dispenser 71 is connected to an inside of the barrel 72, and likewise the inside of the barrel 72 is connected to the inside of the accommodating tub body 41 by a connecting member such as a hose 73. The dispenser 71, which is connected to a control unit (not shown), discharges a predetermined amount of air at a predetermined timing according to a control signal sent from the control unit. The discharged air flows through the hose 73 into the barrel 72. Since the coating liquid is received in the barrel 72, the coating liquid received in the barrel 72 is ejected by the air discharged by the dispenser 71, and flows through the hose 73 into the accommodating tub body 41.

The following describes how the electrical wire coating apparatus 1 with the above-described configuration forms the coating layer 23 on the outer surface 22a of the electrical wire 2. Firstly, the one end 2a of the electrical wire 2 is held by the clamping portion 51, and the accommodating tub 4 is secured upon the second retaining member 52. Secondly, the coating agent is supplied from the supply unit 7 to the sponges 3 in the accommodating tub 4, and the sponges 3 are impregnated with the coating agent. Next, the driving mechanism causes the second retaining member 52 and the accommodating tub 4 is secured to approach the clamping portion 51. The one end 2a of the electrical wire 2 is inserted into the accommodating tub 4 through the slit 45 disposed in the pair of indentations 6. The one end 2a of the electrical wire 2 is then inserted into the groove 32 between the sponges 3, until the electrical wire 2 finally reaches the lower end of the slit 45, i.e., a region around the deepest portion 6a of the indentation 6. Meanwhile, the coating agent impregnating the sponge 3 is applied to the outer surface 22a of the electrical wire 2.

After that, the driving mechanism causes the second retaining member 52 to move away from the clamping portion 51, and the electrical wire 2 is now positioned outside of the accommodating tub 4. Meanwhile, the excessive coating agent is taken away by virtue of the recesses 33 provided on the inner surface 32a of the groove 32. The outer surface 22a of the electrical wire 2, to which the coating agent has been applied, is dried, the solvent in the coating liquid evaporates, and the coating layer 23 is formed on the outer surface 22a of the electrical wire 2 using the coating material.

The electrical wire coating apparatus according to the above embodiment has the pair of the elastic sponges 3 with which the coating liquid made of the coating material and the solvent in which the coating material is dissolved for forming the coating layer 23, an accommodating tub 4 that accommodates the pair of sponges 3, the moving unit 5 that holds the electrical wire 2 and causes the electrical wire 2 and the accommodating tub 4 to move close to and away from each other in the direction orthogonal to the longitudinal direction of the electrical wire 2, and a pair of indentations 6 that allows the electrical wire 2 moving close to and away from the accommodating tub 4 to be accommodated into the accommodating tub 4. By virtue of this construction and arrangement, it is possible to form the coating layer 23 by accommodating a desired portion of the electrical wire 2 in its longitudinal direction into the accommodating tub 4, and letting the desired portion contact the pair of sponges 3. It is possible to prevent the coating agent from adhering to the tip 2b of the electrical wire 2 while the coating layer 23 can be formed on the cover portion 22 of the electrical wire 2 only, and thus degradation of mechanical characteristics and electrical conductivity of the electrical wire 2 can be effectively prevented.

Since the pair of the sponges 3 has the groove 32 used to pass the electrical wire 2 that is accommodated in the pair of indentations 6, the electrical wire 2 can be passed through the groove 32 and positioned between the pair of the sponges 3, and thereby the electrical wire 2 can be smoothly positioned in the pair of the sponges 3.

Since the plurality of the recesses 33 are provided on the inner surface 32a of the groove 32, the excessive coating liquid applied to the outer surface 22a of the electrical wire 2 can flow into the recesses 33, and thereby the amount of used coating liquid can be reduced and the coating layer 23 can be formed uniformly on the outer surface 22a of the electrical wire 2. The portions of the pair of indentations 6 residing at both ends in the longitudinal direction of the electrical wire 2 are provided with the second sponge 43 being elastic, elastically deforming and communicating with the groove 32 to allow passage of the electrical wire 2 therethrough when the electrical wire 2 is accommodated in the pair of indentations 6, and having a slit 45 that seals the pair of the indentations 6 by virtue of resilient restoration when the electrical wire 2 is located outside of the pair of indentations 6. Accordingly, the coating liquid impregnating the pair of sponges 3 is protected against spilling through the pair of the indentations 6 to the outside of the accommodating tub 4. Since supply unit 7 supplies the pair of the sponges 3 with the coating liquid, the coating liquid can be automatically supplied to the pair of the sponges 3, and thus efficiency of manufacturing the electrical wires is improved.

Since, the electrical wire 2 is inserted into and taken out of the accommodating tub 4 to form the coating layer 23 on the outer surface 22a of the electrical wire 2 by causing the electrical wire 2 and the accommodating tub 4, which accommodates the pair of elastic sponges 3 impregnated with the coating liquid made of the coating material forming the coating layer 23 and the solvent in which the coating material is dissolved, to move close to and away from each other, the desired portion of the electrical wire 2 in its longitudinal direction can be accommodated in the accommodating tub 4 so as to come into contact with the pair of the sponges 3 so as to form the coating layer 23, and, therefore, the coating agent is not applied to the tip 2b of the electrical wire 2, and the coating layer 23 can be formed on the cover portion 22 of the electrical wire 2 only. The degradation of the mechanical characteristics and the electrical conductivity of the electrical wire 2 can be effectively prevented. The electrical wire coating apparatus 1 according to the above embodiment forms the coating layer 23 using the coating material (i.e., an undercoating material) on the outer surface 22a of the cover portion 22 of the electrical wire 2 to which the coloring material is yet to be applied. However, it is also possible to form the coating layer 23 using the coating material (i.e., a top coating material) on the outer surface of the cover portion 22 to which the coloring material has already been applied. In the above embodiment, the driving mechanism causes the accommodating tub 4 to move close to and away from the electrical wire 2. It is of course possible to cause the electrical wire 2 to move close to and away from the accommodating tub 4. In addition, as illustrated in FIG. 8, the retaining member 55 that holds the electrical wire 2 has the retaining member body 56 in a form of a strip and the plurality of the clamping portions 51 secured on the retaining member body 56. Nevertheless, the retaining member 55 may hold a plurality of the electrical wires 2, and a second driving mechanism (not shown) may be provided that moves the retaining member 55 or the second retaining member 52 so that the plurality of the electrical wires 2 are sequentially positioned at a space above the accommodating tub 4. It should be noted that the embodiment described above is illustrated as an example of the possible embodiments of the present invention, and that numerous modifications and variations can be effectuated within the spirit and scope of the present invention.

Claims

1. An electrical wire coating apparatus for forming a coating layer on an outer surface of an electrical wire comprising:

(a) an elastic porous member that is impregnated with a coating liquid for forming the coating layer, the coating liquid being made of a coating material and a solvent in which the coating material is dissolved;

(b) an accommodating tub that receives the porous member;

(c) a moving unit that holds the electrical wire and moves the electrical wire and the accommodating tub relative to each other in a direction orthogonal to a longitudinal direction of the electrical wire; and

(d) an electrical wire receiving part that allows the electrical wire moving relative to the accommodating tub to be accommodated in the accommodating tub.

2. The electrical wire coating apparatus as set forth in claim 1, wherein the porous member has a groove configured to pass therethrough the electrical wire that is received in the electrical wire receiving part.

3. The electrical wire coating apparatus as set forth in claim 2, wherein a plurality of recesses are formed on an inner surface of the groove.

4. The electrical wire coating apparatus as set forth in either of claims 2 or 3, wherein a second porous member is provided at a portion of the electrical wire receiving part corresponding to each of both ends the electrical wire in the longitudinal direction, the second porous member is elastic and configured to elastically deform so as to communicate with the groove, the second porous member has a slit that allows the electrical wire to pass therethrough when the electrical wire is received in the electrical wire receiving part, and the slit is resiliently restored and closed when the electrical wire is positioned outside of the electrical wire receiving part.

5. The electrical wire coating apparatus as set forth in any of the preceding claims, further comprising a supply unit that supplies the porous member with the coating liquid.

6. An electrical wire coating method for forming a coating layer on an outer surface of an electrical wire, comprising the steps of: (a) moving the electrical wire and an accommodating tub relative to each other, the accommodating tub accommodating an elastic porous member impregnated with a coating liquid for forming the coating layer, the coating liquid made of a coating material and a solvent in which the coating material is dissolved; and (b) forming the coating layer on the outer surface of the electrical wire by placing the electrical wire in and out of the accommodating tub.