Wire manufacturing method wire manufacturing apparatus and wire

This invention intends to provide a method and apparatus for manufacturing an electric wire, capable of easily changing a color applied to the electric wire. The electric wire manufacturing apparatus intends to manufacture an electric wire composed of a core and a cladding. In step S1, the core is supplied from a supply unit. In step S2, in an extrusion cladding unit, the outer periphery of the core is coated with non-color synthetic resin by extrusion cladding to form the cladding. In step S3, the outer surface of the cladding is colored by a coloring unit. The coloring unit includes a plurality of sprayers 15 and 16. In step S3, the sprayers 15 and 16 are exchanged to operate as necessary. In step S4, in a take-up unit, the electric wire is cut into segments each having a desired length, which are wound around a drum.

TECHNICAL FIELD

This invention relates to a method and apparatus for manufacturing an electric wire composed of an electric core and an insulating cladding which clads the core, and the electric wire itself.

BACKGROUND ART

A moving body such as a motor vehicle is equipped with various electronic devices. Therefore, in order to supply electric power from a power source and a control signal from a computer to these electronic devices, a wire harness100is arranged in the motor vehicle. The wire harness includes plural electric wires106(FIG. 10) and connectors attached to the ends thereof.

The electric wire106is composed of a conductive core105(FIG. 10) and a cladding which is made of insulating synthetic resin and clads the core105. The electric wire106is a “clad-wire”. The electric wire106has been manufactured by a manufacturing apparatus100shown inFIG. 10. The manufacturing device illustrated inFIG. 10includes a supply unit101, an extrusion cladding unit102, a cooling water bath103and a take-up unit104.

In manufacturing the electric wire106, the wire manufacturing device100sequentially shifts the core105or electric wire106to the supply unit101, extrusion cladding unit102, cooling water bath103and take-up unit104. In order to shift the core105or electric wire106, the wire manufacturing device100is provided with plural pulleys107.

The supply unit101supplies the core105with no cladding. The extrusion cladding unit102extrudes the insulating synthetic resin to the periphery of the core105to form the cladding. The cladding water bath103cools the cladding which clads the core105with the aid of the extrusion cladding unit102. The take-up unit104cuts the electric wire106composed of the core105and cladding into segments each having a prescribed length and wind them around a drum so that they are in a shipping state. Thus, the electric wire106is manufactured by the electric wire manufacturing apparatus100.

The connector is composed of a conductive terminal metal fitting and a connector housing. The terminal metal fitting is attached to the end of the electric wire106and electrically connected to the core105thereof. The connector housing is formed in a box shape to accommodate the terminal metal fitting.

In assembling the wire harness, the electric wire106is cut into wire segments (referred to electric wires106) each having a prescribed length. Metal fittings are attached to the ends of the wire segments. Thereafter, the terminal metal fittings are inserted into the connector housing. Thus, the wire harness is assembled.

The electric wires106must be distinguished in terms of the size of the core105, substance of the cladding (presence or absence of heat-resistance) and using object. The using object is a system of a motor vehicle in which the electric wires are used, such as an air bag, ABS (Antilock Brake System), a system for supplying a control signal such as a vehicle speed and a power transmission system.

The electric wires are colored with various colors and bear markings in order to identify the using object. For this purpose, in the conventional wire manufacturing device100illustrated inFIG. 10, the extrusion cladding unit102mixes a coloring agent into the synthetic resin for the cladding. The synthetic resin and coloring agent are mixed to color the synthetic resin with the same color as the coloring agent.

The synthetic resin is extruded to the periphery of the core105. Thus, the cladding or electric wire106is colored.

On the other hand, a variety of demands have been made for the motor vehicle from a user. Therefore, it has been demanded that the motor vehicle is equipped with a variety of electronic devices. Thus, as the case may be, one hundred kinds of electric wires are used for the wire harness. In this case, the electric wires106with a wide variety of colors are used. For this reason, the wire manufacturing device100is demanded to be able to change the color of the cladding.

The wire manufacturing apparatus100illustrated inFIG. 10, in order to change the color of the cladding (i.e. electric wire106), the extrusion cladding unit102was temporarily stopped to change the coloring agent to be mixed into the synthetic resin. In this case, in order to manufacture a wide variety of electric wires with a wide variety of colors, the extrusion cladding unit102must be stopped frequently. This reduced the manufacturing efficiency of the electric wires106.

In order to obviate such inconvenience, it has been proposed to change the coloring agent to be mixed into the synthetic resin while the extrusion cladding unit102is driven. In this case, immediately after the coloring agent has been changed, both coloring agents before and after changing are mixed into the synthetic resin so that the cladding is colored with the mixed color. Since the mixed color of the electric wire106is not the color corresponding to the above system, the electric wire106cannot be used fro the wire harness.

Thus, if the coloring agent to be mixed into the synthetic resin is changed while the extrusion cladding unit102is driven, the electric wire involves a portion which cannot be used for the wire harness. This led to a tendency of decreasing the of material yield of the electric wire106.

In order to suppress the wasteful portion of the electric wire106, i.e. suppress the material yield of the electric wire106, in e.g. JP-A-6-150774, it is proposed to apply the liquid color ink with the same color as that of the coloring agent after changing onto the mixed area of the color agents. In this case, if the mixed color (referred to as a base color) and the coloring agent after changing are different in their hue, or the brightness of the base color is lower than that of the coloring agent after changing, the base color might be seen through the liquid color ink. In addition, in this case, the liquid color ink is applied to the cladding after formed, the liquid color ink is apt to come off from the outer surface of the cladding.

In this way, in the technique described in JP-A-6-150774, the color of the liquid color ink must be determined according to the base color. This made it difficult to change the color agent from a dark coloring agent to a bright coloring agent. Thus, the technique described in JP-A-6-150774 has a limitation in changing the coloring agent that the coloring agent must be changed into the coloring agent with lower brightness.

Further, in the conventional wire manufacturing apparatus100, in the extrusion cladding, the coloring agent is mixed into the synthetic resin constituting the cladding. The cladding is colored at the same time as the core is coated with the cladding. Accordingly, the electric wire106used for the motor vehicle has about one hundred kinds of product numbers in terms of the color of the outer surface (the electric wire106has a vast number of product numbers inclusive of those with different wire diameters).

Thus, a wire manufacturer or wire harness manufacturer must store about one hundred electric wires with different colors of the outer surface temporarily or for a long period. Therefore, a large space is required to store the electric wires and a troublesome work is necessary to manage the product numbers of the electric wires106.

Accordingly, a first object of this invention is to provide a method and apparatus for manufacturing an electric wire which can change the color for coloring the electric wire and electric wire itself. A second object of this invention is to provide an electric wire in which the coloring color is difficult to come off.

DISCLOSURE OF THE INVENTION

In order to attain the above first object, an embodiment of the present invention proposes a method for manufacturing an electric wire composed of a conductive core and a cladding which is made of insulating synthetic resin and clads the core, characterized by comprising:

an extrusion cladding step of cladding an outer periphery of the core with non-colored synthetic resin by extrusion cladding to form the cladding; and

a coloring step of coloring an outer surface of the cladding of non-colored synthetic resin.

In this configuration, the extrusion cladding step of forming the cladding and the coloring step of coloring the electric wire are implemented individually. Therefore, by changing the color in the coloring step, the color applied to the electric wire can be easily changed. In the extrusion cladding step, the cladding is coated with the non-color synthetic resin. Therefore, the product numbers (kinds of the color of the outer surface) of the electric wire which is obtained by extrusion cladding can be reduced. In the coloring step, the outer surface of the non-colored cladding is colored. Therefore, even when the outer surface of the non-colored cladding is colored with the color having higher brightness than that of the outer surface, the non-colored resin can be hidden by the color adopted in the coloring step.

In this specification, to color the outer surface of the cladding of the electric wire is to color the outer surface of the cladding with a coloring agent. The coloring agent is a liquid material in which a coloring material (industrial organic material) is dissolved or dispersed in water or other solvent. The organic material may be dye and pigment (most of them is the organic material, and synthetic material). As the case may be, the dye is used as the pigment or the pigment is used as the dye. More specifically, in the specification, the coloring agent refers to both of a coloring solution and a paint.

The coloring solution refers to a solution in which the dye is dissolved or dispersed in a solvent. The paint refers to a solution in which the pigment is dispersed in a fluid dispersion. Therefore, when the outer surface of the cladding is colored with the coloring solution, the dye sinks into the cladding. On the other hand, the outer surface of the cladding is colored with the paint, the pigment does not sink into the cladding, but is applied onto the outer surface. Specifically, in the specification, to color the outer surface of the cladding refers to dye the outer surface of the cladding in its entirety or portion with the dye and apply the pigment on the outer surface of the cladding in its entirety or portion.

The above solvent and fluid dispersion are desired to have affinity with the synthetic resin which constitutes the cladding of the electric wire. In this case, the dye surely sinks in the cladding of the electric wire, or the pigment surely applies on the outer surface of the cladding of the electric wire.

In order to attain the first object, another embodiment of the present invention proposes a method for manufacturing an electric wire characterized in that the coloring step is executed immediately after the extrusion cladding step.

In this configuration, since the coloring step is executed immediately after the extrusion cladding step, the temperature of the cladding heated to a high temperature in the extrusion cladding step can be reduced by the evaporation heat when the coloring agent used in the coloring step is dried.

The cladding heated to the high temperature in the extrusion cladding step is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding.

In order to attain the first object, another embodiment of the present invention proposes a method for manufacturing an electric wire characterized in that in the coloring step, the outer surface of the cladding is colored with a plurality of colors, and the color applied to the outer surface can be changed as necessary.

In this configuration, in the coloring step, the outer surface of the cladding can be colored with a plurality of colors, and the color applied to the outer surface can be changed. Therefore, the cladding can be colored with various colors which can be changed.

In order to attain the first object, another embodiment of the present invention proposes a method for manufacturing an electric wire characterized in that in the coloring step, any position of the electric wire is measured and the outer surface of the cladding is colored by exchanging a plurality of coloring portions capable of coloring the outer surface of the cladding in a single color, respectively.

In this configuration, any position of the electric wire is measured to exchange the plurality of coloring portions. Therefore, the electric wire can be colored with a plurality of colors. In addition, without stopping the operation of manufacturing the electric wire temporarily, the color applied to the electric wire can be easily changed. Further, any position of the electric wire can be measured. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

In order to attain the first object, another embodiment of the present invention proposes a method for manufacturing an electric wire characterized in that the core of the electric wire is moved to manufacture the electric wire; the coloring portions are apart from one another in a direction of moving the core; and when the electric wire moves over an interval between the coloring portions while an upstream coloring portion of the coloring portions is stopped, a downstream coloring portion thereof is operated.

In this configuration, the upstream coloring portion is stopped, and when the electric wire moves over an interval between the coloring portions while an upstream coloring portion of the coloring portions is stopped, the downstream coloring portion thereof is operated. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

In order to attain the first object, another embodiment of the present invention proposes a method for manufacturing an electric wire characterized in that the core of the electric wire is moved to manufacture the electric wire; the coloring portions are apart from one another in a direction of moving the core; and where an upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is operated, when the electric wire moves over an interval between the coloring portions, the downstream portion is stopped.

In this configuration, where the upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is operated, when the electric wire moves over an interval between the coloring portions, the downstream portion is stopped. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

In order to attain the above object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire composed of a conductive core and a cladding which is made of insulating synthetic resin and clads the core, characterized by comprising:

an extrusion cladding unit of cladding an outer periphery of the core with non-colored synthetic resin by extrusion cladding to form the cladding; and

a coloring unit of coloring an outer surface of the cladding of non-colored synthetic resin.

In this configuration, the extrusion cladding unit of forming the cladding and the coloring unit of coloring the electric wire are individually provided. Therefore, by changing the color in the coloring step, the color applied to the electric wire can be easily changed. In the extrusion cladding step, the cladding is coated with the non-color synthetic resin. Therefore, the product numbers (kinds of the color of the outer surface) of the electric wire which is obtained by the extrusion cladding unit can be reduced. In the coloring unit, the outer surface of the non-colored cladding is colored. Therefore, even when the outer surface of the non-colored cladding is colored with the color having higher brightness than that of the outer surface, the non-colored resin can be hidden by the color adopted in the coloring unit.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that the core is moved to manufacture the electric wire,

and the coloring unit is arranged downstream of and immediately after the extrusion cladding unit in a direction of moving the core.

In this configuration, since the coloring unit is arranged immediately after the extrusion cladding unit, the temperature of the cladding heated to a high temperature in the extrusion cladding unit can be reduced by the evaporation heat when the coloring agent used in the coloring unit is dried.

The cladding heated to the high temperature in the extrusion cladding unit is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that the coloring unit includes a plurality of coloring portions capable of coloring the outer surface of the cladding in a single color, respectively, and an exchanging portion for exchanging the coloring portions for coloring the outer surface of the cladding.

In this configuration, the coloring unit includes a plurality of coloring portions and the exchanging portion. Therefore, by exchanging the coloring portions to operate in the coloring unit, the outer surface of the cladding can be colored with various colors.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that the coloring unit includes a plurality of coloring portions capable of coloring the outer surface of the cladding in a single color, respectively, a measuring means for measuring an optional position of the electric wire, and an exchanging means for exchanging the coloring portions for coloring the outer surface of the cladding on the basis of the optional position measured by the measuring means.

In this configuration, the coloring unit includes the plurality of coloring portions. Therefore, the electric wire can be colored with the plurality of colors. In addition, the exchanging means can exchange the coloring portions. Therefore, without temporarily stopping the coloring unit, i.e. electric wire manufacturing apparatus, the color applied to the electric wire can be easily changed. Further, the measuring means can measure any position of the electric wire. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that the coloring portions are arranged apart from each other in a direction of moving the core; and

the measuring means measures the optional position by measuring information corresponding to a quantity of movement of the electric wire in a direction of moving the core.

In this configuration, the measuring means measures any position of the electric wire by measuring the information corresponding to a quantity of movement of the electric wire. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that when the exchanging means changes the coloring portion for coloring the outer surface from an upstream coloring portion of the coloring portions to a downstream coloring portion thereof in a direction of moving the core, the exchanging portion stops the upstream coloring portion and operates the downstream coloring portion when a quantity of movement of the electric wire measured by the measuring means becomes equal to the interval between the plurality of coloring portions.

In this configuration, the exchanging portion stops the upstream coloring portion and operates the downstream coloring portion when a quantity of movement of the electric wire measured by the measuring means becomes equal to the interval between the plurality of coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric wire characterized in that when the exchanging means changes the coloring portion for coloring the outer surface from a downstream coloring portion of the coloring portions to an upstream coloring portion thereof in a direction of moving the core, the exchanging portion operates the upstream coloring portion while the downstream coloring portion is being operated, and stops the downstream coloring portion when a quantity of movement of the electric wire measured by the measuring means becomes equal to the interval between the plurality of coloring portions.

In this configuration, the exchanging portion operates the upstream coloring portion while the downstream coloring portion is being operated, and stops the downstream coloring portion when a quantity of movement of the electric wire measured by the measuring means becomes equal to the interval between the plurality of coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided.

In order to attain the first object, another embodiment of the present invention proposes an apparatus for manufacturing an electric characterized in that each of the coloring portions sprays a coloring agent in a sol state on the outer surface.

In this configuration, the coloring portion sprays the coloring agent in a sol state. Therefore, when the exchanging means exchanges the coloring portions, the color applied to the electric wire can be changed immediately.

In order to attain the second object, another embodiment of the present invention proposes an electric wire composed of a conductive core and a cladding which is made of insulating synthetic resin and clads the core, characterized in that immediately after an outer periphery of the core is coated with the synthetic resin by extrusion cladding to provide the cladding, the outer surface of the cladding is colored.

In this configuration, the cladding heated to the high temperature by the extrusion cladding is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding.

In order to attain the second object, another embodiment of the present invention proposes an electric wire characterized in that a plurality of coloring portions capable of coloring the outer surface in single color, respectively are exchanged to color the outer surface at any measured position, and the outer surface is composed of a first area colored in a first color, a second area colored in a second color and a boundary therebetween.

In the configuration, any position is measured and the coloring portions are exchanged to color the outer surface. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

In order to attain the second object, another embodiment of the present invention proposes an electric wire characterized in that the electric wire is manufactured by moving the core; the coloring portions are apart form one another in a direction of moving the core; and after the electric wire is moved over an interval between the coloring portions while an upstream coloring portion of the coloring portions stops, a downstream coloring portion is operated.

In this configuration, an upstream coloring portion of the coloring portions is stopped, and when the electric wire is moved over an interval between the coloring portions while a downstream coloring portion is operated to color the outer surface. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Thus, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

In order to attain the second object, another embodiment of the present invention proposes an electric wire characterized in that the electric wire is manufactured by moving the core; the coloring portions are apart form one another in a direction of moving the core; and an upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is being operated, and the downstream coloring portion is stopped after the electric wire moves over an interval between the coloring portions.

In this configuration, the upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is being operated, and the downstream coloring portion is stopped after the electric wire moves over an interval between the coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Thus, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified.

BEST MODE FOR CARRYING OUT THE INVENTION

Now referring toFIGS. 1 to 9, an explanation will be given of a method and apparatus for manufacturing an electric wire according to an embodiment of this invention. An electric wire manufacturing apparatus shown inFIG. 1according to an embodiment of this invention is an apparatus which once manufactures a non-colored electric wire2aas shown inFIG. 4and colors the non-colored wire2ato manufacture an electric wire2as shown inFIG. 5. Incidentally, since these electric wires2and2ahave the same construction, their like portions are designated by like reference numerals.

The electric wire2constitutes the wire harness of the moving body such as a motor vehicle. The electric wire2,2a, as shown inFIGS. 4 and 5, is composed of a conductive core3and insulating cladding4. The core3is composed of a plurality of twisted strands. The strand is made of conductive metal. The core3may be composed of a single strand. The cladding4is made of synthetic resin such as polyvinylchloride: PVC. The cladding4clads the core3.

The outer surface of the cladding4of the non-colored electric wire2a, as shown inFIG. 4, is colored with the color P of the synthetic resin itself constituting the cladding4. In the non-colored electric wire2a, the coloring agent is not mixed with the synthetic resin constituting the cladding4. The electric wire with the outer surface4awith the color P is referred to as a non-colored electric wire2a.

On the other hand, the outer surface4aof the cladding4of the electric wire2is colored with the color different from the synthetic resin of the cladding4. The outer surface of the cladding4of the electric wire2is composed of a first portion31colored with a first color B (shaded inFIG. 5), a second portion32with a second color R (shaded inFIG. 5) and a boundary S therebetween. The boundary S is clearly indicated. The outer surface4aof the cladding4constitutes the outer surface of the electric wire2.

The electric wires each having the structure described above are tied up in a bundle. The ends of the electric wires are connected to connectors so as to constitute the wire harness described above. The connectors are connector-coupled with various connectors of electronic devices of a motor vehicle. The wire harness, i.e. electric wires transmit various signals and electric power to the electronic devices.

The wire manufacturing apparatus1serves to manufacture the electric wires each having the structure as described above. The wire manufacturing apparatus, as shown inFIG. 1, includes a supply unit10, an extrusion cladding unit11, a coloring unit12and a take-up unit13.

The wire manufacturing apparatus1sequentially shifts the core3to the supply unit10, extrusion cladding unit11, coloring unit12and take-up unit13to manufacture the electric wire2. The wire manufacturing apparatus1is provided with a plurality of pulleys for shifting the core3or electric wire2,2a.

The supply unit10supplies the core3not coated with the cladding4. The extrusion cladding unit11, after has once liquefied the non-colored synthetic resin (heated it to a high temperature), applies it on the entire periphery of the core3supplied from the supply unit10. The extrusion cladding unit11extrusion-clads the non-colored synthetic resin on the periphery of the core3supplied from the supply unit10to form the cladding4. The extrusion cladding unit11manufactures the non-colored electric wire2aas shown inFIG. 4. The cladding4, immediately after it has been manufactured by the extrusion cladding unit11(immediately after step S2described later), is at a high temperature.

The coloring unit12is arranged downstream and immediately after the extrusion cladding unit11in the moving direction of the core3or electric wire2,2a(direction of arrow K inFIG. 2). The arrow K represents the moving direction of the core3. The coloring unit12colors the outer surface4a(FIG. 4) of the cladding4of the core3heated to a high temperature with a desired color. The detailed structure of the coloring unit12will be described later.

In this specification, to color the outer surface4aof the cladding4of the electric wire2is to color the outer surface of the cladding4with a coloring agent. The coloring agent is a liquid material in which a coloring material (industrial organic material) is dissolved or dispersed in water or other solvent. The organic material may be dye and pigment (most of them is the organic material, and synthetic material). As the case may be, the dye is used as the pigment or the pigment is used as the dye. More specifically, in the specification, the coloring agent refers to both of a coloring solution and a paint.

The coloring solution refers to a solution in which the dye is dissolved or dispersed in a solvent. The paint refers to a solution in which the pigment is dispersed in a fluid dispersion. Therefore, when the outer surface4aof the cladding4is colored with the coloring solution, the dye sinks into the cladding4. On the other hand, when the outer surface4aof the cladding4is colored with the paint, the pigment does not sink into the cladding4, but is applied onto the outer surface4a. Specifically, in the specification, to color the outer surface of the cladding4refers to dye the outer surface of the cladding4in its entirety or portion (terminal) with the dye and apply the pigment on the outer surface of the cladding4in its entirety or portion.

The above solvent and fluid dispersion are desired to have affinity with the synthetic resin which constitutes the cladding of the electric wire2. In this case, the dye surely sinks in the cladding4of the electric wire2, or the pigment surely applies on the outer surface4aof the cladding4of the electric wire2.

The take-up unit13cuts the electric wire3composed of the core3and the cladding4with the colored outer surface4ainto segments each having a prescribed length. The take-up unit13winds the electric wire around a drum and places it in an off-the-shelf state.

An explanation will be given of the construction of the coloring unit12. The coloring unit12, as seen fromFIG. 2, includes a first sprayer15which is an upstream coloring portion, a second sprayer16which is a downstream coloring portion, an exchanging portion23and an input device19which is an input means. Namely, the coloring unit12is provided with a plurality of sprayers15,16which serve as coloring portions. In the illustrated example, the coloring unit12is provided with two sprayers15,16, but may be provided with three or more sprayers15,16.

The first sprayer15is provided with a first plurality of nozzles20, a first liquid supplying source (not shown) and a first gas supplying source (not shown). The first nozzles20are opposite to the outer surface4aof the cladding4which clads the core3. The first plurality of nozzles20are arranged at regular intervals circumferentially around the electric wire2a. Arrow K denotes the direction of moving the core3. InFIG. 2, the first sprayer15is provided with first two nozzles20on a diagonal line around the electric wire2a. However, if necessary where the entire periphery of the electric wire2ais colored, the first sprayer15may be provided with three or more first nozzles20.

The first liquid supply source serves to supply the coloring liquid or paint of the first color (shaded by inFIGS. 6 to 8). The first gas supply source serves to supply pressurized gas into the first nozzle20. In the configuration described above, the first sprayer15sprays the coloring liquid or paint with the first color B as well as the gas from the first nozzle20toward the outer surface of the cladding4. The first sprayer15disperses the coloring liquid or paint (i.e. coloring agent) with the first color B into the gas so that it is sprayed to the outer surface of the cladding4in its “sol” (aerosol) state.

The second sprayer16is provided with a second plurality of nozzles21, a second liquid supplying source (not shown) and a second gas supplying source (not shown). The second nozzles21are opposite to the outer surface4aof the cladding4which clads the core3. The second plurality of nozzles21are arranged at regular intervals circumferentially around the electric wire2a. InFIG. 2, the second sprayer16is provided with second two nozzles21on a diagonal line around the electric wire2a. However, if necessary where the entire periphery of the electric wire2ais colored, the second sprayer16may be provided with three or more second nozzles21.

The second liquid supply source serves to supply the coloring liquid or paint of the second color (shaded by inFIGS. 8 and 9). The second gas supply source serves to supply pressurized gas into the second nozzle21. In the configuration described above, the second sprayer16sprays the coloring liquid or paint with the second color B as well as the gas from the second nozzle21toward the outer surface of the cladding4. The second sprayer16disperses the coloring liquid or paint (i.e. coloring agent) with the second color R into the gas so that it is sprayed to the outer surface of the cladding4in its “sol” (aerosol) state.

The second nozzles21of the second sprayer16are arranged downstream of the first nozzles20in the direction moving the core3indicated by arrow K. The second nozzles21are apart from the first nozzles20by distance K in the direction of arrow K. The distance L is equal to the interval between the first sprayer15and the second sprayer16in the direction of arrow K.

An exchanging portion23includes an encoder17serving as a measuring means and a control device18serving as an exchanging means. The encoder17is provided with a rotor22. The rotor22is rotatable around the axis core. The outer surface of the rotor22is in contact with the cladding4. The rotor22, when the core3, i.e. electric wire2,2amoves in the direction of arrow K, rotates. Namely, the rotor22rotates around the axis core with moving of the core3, i.e. electric wire2,2a. It is of course that the moving distance of the core3, i.e. electric wire2in the direction of arrow K is proportional to the number of revolutions of the rotor22.

The encoder17is connected to the control device18. The encoder17, when the rotor22rotates by a prescribed angle, issues a pulsating signal to the control device18. Namely, the encoder17issues the information corresponding to the moving direction of the core3, i.e. electric wire2,2ain the direction of arrow K toward the control device18. In this way, the encoder17measures the information corresponding to the moving distance of the electric wire2,2aand issues the information relative to any position of the electric wire2.

The control device18is a computer equipped with a known RAM, ROM, CPU, etc. and controls the entire coloring unit12. On the basis of the command received from an input device19or a program stored in the above ROM, the control device18operates one of the first sprayer15and the second sprayer16to color the outer surface of the cladding4with the first color B or second color R. The control device18stores the distance L between the nozzles20and21.

The control device18changes the sprayer from the first sprayer15into the second sprayer16so that the state where the cladding4is colored with the first color B is changed into the state where the cladding4is colored with the second color R. Alternatively, The control device18changes the sprayer from the second sprayer16into the first sprayer15so that the state where the cladding4is colored with the second color R is changed into the state where the cladding4is colored with the first color B.

Where after the first sprayer15has been stopped, the second sprayer16is operated, i.e. the sprayer15,16for coloring the outer surface4ais changed from the first sprayer15to the second sprayer16, the control device18stops the first sprayer15in the state where the first sprayer15is operating. InFIG. 6, the area being colored by the first sprayer15is shaded by B. Then, as shown inFIG. 7, the area shaded by B moves toward the second sprayer16.

On the basis of the information supplied from the encoder17, the control device18determines whether or not the core3, i.e. the electric wire2,2ahas moved by the distance L. If it is determined that the electric wire2,2ahas moved by the distance L, as shown inFIG. 8, the second sprayer16is operated. In this way, after the first sprayer15has stopped, when the quantity of movement of the electric wire2,2ameasured by the encoder17becomes equal to the distance L between the nozzles20and21, the control device18operates the second sprayer16. Then, as seen fromFIG. 9, the outer surface of the cladding4of the electric wire2,2ais colored by the second sprayer16. Incidentally, inFIGS. 8 and 9, the area colored by the second sprayer16is shaded by R.

Where after the second sprayer16has been stopped, the first sprayer15is operated, i.e. the sprayer for coloring the outer surface4ais changed from the second sprayer16to the first sprayer15, the control device18operates the first sprayer16in the state where the second sprayer16is operating. On the basis of the information supplied from the encoder17, the control device18determines whether or not the core3, i.e. the electric wire2,2ahas moved by the distance L.

If it is determined that the electric wire2,2ahas moved by the distance L, the second sprayer16is stopped. In this way, the control device18operates the first sprayer15in the state where the second sprayer16is operating and stops the sprayer16when the quantity of movement of the electric wire2measured by the encoder17becomes equal to the distance L between the nozzles20and21.

As described above, on the basis of the information from the encoder17, the control device18controls the sprayers15and16so that the first color B and the second color R do not overlap each other on the outer surface4aof the cladding4. The control device18controls the sprayers15and16so that the outer surface of the cladding4is necessarily colored with either one of the first color B and second color R. In the exchanging portion23having the configuration described above, on the basis of the information from the encoder17, the control device18changes the sprayer15,16for coloring the outer surface4aof the cladding4to change the color which colors the outer surface4aof the cladding4.

The input device19is used to set the timing of changing the sprayer15,16, for example. Namely, the input device19is used to make various operations of the coloring unit12. The input device19may be one of various devices for inputting information inclusive of a known keyboard, various switches, various recording medium driving device such as a CD-ROM drive.

The coloring unit12requires the sprayers15and16whose number corresponds to the number of colors used to color the electric wire2. However, one of the sprayers15and16is operated, whereas the other sprayer may be washed for preparation of coloring of another color. Therefore, as long as there are at least two sprayers15,16, the electric wire2can be colored with various colors.

Now referring toFIG. 3, an explanation will be given of a process of manufacturing the electric wire2using the electric wire manufacturing apparatus1having the configuration described above.

In step S1, the core3is supplied from the supply unit10. In step S2, in the extrusion cladding unit11, the core3is coated with non-color synthetic resin by extrusion cladding to form the cladding4, thereby providing the non-colored electric2a. Step S2refers to a cladding step in this specification.

Immediately after the cladding4has been formed, in step S3, the coloring unit12operates one of the sprayers15and16so that the outer surface4aof the cladding4of the non-colored synthetic resin is colored with the coloring liquid or paint. In this step S3, the coloring unit12operates one of the sprayers15and16selected at a desired timing. Step S3refers to a coloring step in this specification. The manufacturing process proceeds to step S4.

Step S3or coloring step is implemented immediately after step S2or extrusion cladding step. Since the coloring unit12is provided with the plurality of sprayers15and16, the outer surface4aof the cladding4can be colored with a plurality of colors. Therefore, the outer surface of the cladding4acan be colored with the color selected from these plurality of colors, and the color can be changed as necessary.

In step S4, the take-up unit13cuts the electric wire2, composed of the core3and cladding4colored by the coloring unit12, into segments each having a desired length which are wound around the drum. Thus, the electric wire2constituting the wire harness2can be manufactured.

In this embodiment, the step S2for forming the cladding4and the step S3for coloring the outer surface4aof the cladding4of the electric wire2are implemented individually Therefore, by changing the color in step S3, the color for the outer surface4aof the cladding4of the electric wire2can be easily changed.

Further, in step S2or by the extrusion cladding unit11, the cladding4is formed of the non-color synthetic resin. Therefore, the product numbers (kinds of the color coloring the outer surface4a) of the electric wire2awhich is obtained by extrusion cladding can be reduced. Thus, the space for storing the electric wire2aand effort to manage the product numbers can be also reduced.

In step S3or by the coloring unit12, the outer surface4aof the non-colored cladding4is colored. Therefore, even when the outer surface4aof the non-colored cladding4is colored with the color having higher brightness than that of the outer surface4a, the non-colored resin can be hidden by the color adopted in step S3by the coloring unit12. Therefore, in step S3or by the coloring unit12, the electric wire2can be colored with any color which can be changed without limit. Thus, the limitation when the color for coloring electric wire2is changed can be removed.

Further, step S3is executed immediately after step S2. Namely, the coloring unit12is arranged immediately downstream of the exclusion cladding unit11in the direction K of moving the core3. The coloring unit12sprays the coloring agent in a sol state. Therefore, the temperature of the cladding4heated to a high temperature in step S2can be reduced by the evaporation heat when the coloring agent in the sol state used for coloring in step S3is dried. In step S3, since the cladding4is cooled, the step or device for cooling the cladding4can be omitted.

The cladding4heated to the high temperature in step S2is colored. The electric wire2shown inFIG. 5is made in such a way that the outer surface4aof the cladding4heated to the high temperature by exclusion cladding is colored. In coloring the outer surface4aof the cladding4, the control device18changes the sprayer between the sprayers15and16on the basis of the information from the encoder17.

Thus, since the outer surface of the cladding4is colored before the synthetic resin constituting the cladding4is hardened, the dye of the coloring agent is liable to sink within the cladding4, and the pigment of the paint is liable to bond to the outer surface4aof the cladding4. Therefore, the dye or pigment is difficult to come off from the outer surface of the cladding4. The electric wire thus formed can be used as the electric wire which is arranged in a motor vehicle. Further, since the cladding4heated to the high temperature is colored, heating for drying is not required after the cladding has been colored using the coloring liquid or paint. Therefore, the electric wire manufacturing device1can be further miniaturized.

Further, since the cladding4at the high temperature is sprayed with the coloring agent, the cladding4does not suffer from adverse effects (reduction in the mechanical strength and surface corrugation) as compared with the case where the cladding is previously treated using known swelling agent, solvent, plastic agent, etc. before the coloring agent is sprayed.

Further, the coloring unit12is provided with the plurality of sprayers15and16. Therefore, the electric wire2can be colored with the plurality of colors so that the color for coloring can be easily changed by exchanging the sprayers15,16.

Further, in step S3, i.e. by the coloring unit12, the color applied to the outer surface4aof the cladding4can be changed. Therefore, in step S3, i.e. by the coloring unit12, the cladding4can be colored with various colors. Thus, in changing the color applied to the cladding4, it is not necessary to stop the coloring unit12or electric wire manufacturing apparatus temporarily, thereby preventing the efficiency of manufacturing the electric wire2from being reduced.

The coloring unit12is provided with the plurality of sprayers15and16. Therefore, the electric wire2can be colored with the plurality of colors. The control device18can change the sprayer between the sprayers15and16. For this reason, without temporarily stopping the coloring unit12, i.e. the electric wire manufacturing apparatus1, the color applied to the electric wire2can be easily changed, thereby preventing the efficiency of manufacturing the electric wire from being reduced.

Further, the encoder17can acquire the information corresponding to the moving distance of the electric wire2to measure any position of the electric wire2. For this reason, when the sprayers15and16are exchanged, the area where the plurality of colors overlap on the electric wire2and the non-colored area can be suppressed. This suppresses reduction in the material yield of the electric wire2.

The sprayers15and16spray the coloring agent in the sol state. Therefore, when the control device18changes the sprayer between the sprayers15and16, the color applied to the electric wire2can be changed immediately. For this reason, when the sprayers15and16are exchanged, the area where the plurality of colors overlap on the electric wire2and the non-colored area can be suppressed. This suppresses reduction in the material yield of the electric wire2.

When the sprayer15,16is changed, the color applied to the electric wire2can be immediately changed. Therefore, the interval L between the sprayers15and16can be narrowed. Thus, the coloring unit12, i.e. the electric wire manufacturing apparatus1can be miniaturized.

The electric wire2colored by the coloring unit12is manufactured by the electric wire manufacturing apparatus1. The coloring unit12includes the sprayers15,16which spray the coloring agent in the sol state, encoder17for acquiring the information on the movement of the electric wire2and the control device18which switches between the sprayers15and16. Therefore, the boundary S between the first area31colored with the first color B and the second area32colored with the second color R can be clarified. This avoids any overlapping portion of the first color B and the second color R and the area not colored with both colors B and R, thereby suppressing reduction in the material yield of the electric wire2.

In the embodiment described above, the encoder17measures any position of the electric wire2. However, in place of the encoder, this invention can adopt an image pick-up means such as a CCD camera and a discriminating means for identifying any position of the electric wire2from the image acquired by the image pick-up means.

In the embodiment described above, the coloring unit12is arranged immediately downstream of the extrusion cladding unit11. However, in this invention, the coloring unit12may be attached integrally to the take-up unit13. In short, in this invention, after the core3has been coated with the cladding3, the coloring unit2may be arranged at any position in the electric wire manufacturing apparatus1.

Further, in the embodiment described above, the sprayers15and16are used as a coloring portion of the coloring unit12. However, in this invention, as the coloring portion in the coloring unit12, a marker for applying paint or pigment on the outer surface4amay be arranged in contact with the outer surface4aof the cladding4.

Further, in the embodiment described above, the sprayers15and16spray the aerosol composed of the coloring liquid or paint and gas onto the outer surface of the cladding4. However, in this invention, as long as the coloring liquid or paint sprayed onto the outer surface4aof the cladding4from the sprayers15and16is in the sol state, various kinds of gases may be used in place of the gas.

Further, in the embodiment described above, the electric wire2constituting the wire harness arranged in a motor vehicle was employed. However, the electric wire2manufactured by the manufacturing apparatus1according to this invention may be applied to various electronic devices or various electric machine such as a portable computer as well as the motor vehicle.

Additionally, in this invention, as the means for coloring the outer surface4aof the cladding4, various means inclusive of immersion, spraying, jetting, printing, transfer, etc. may be employed. Further, as the coloring liquid and paint, acryl paint, ink (dye or pigment), UV ink may be employed.

INDUSTRIAL APPLICABILITY

As understood from the description hitherto made, in an embodiment of the present invention, the extrusion cladding step and the coloring step are individually implemented. Therefore, by changing the color in the coloring step, the color applied to the electric wire can be easily changed. In the extrusion cladding step, the cladding is formed from non-colored synthetic resin. Therefore, the product numbers (kinds of the color coloring the outer surface) of the electric wire which is obtained by extrusion cladding can be reduced. Thus, the space for storing the electric wire2aand effort to manage the product numbers can be also reduced.

In another embodiment of the present invention, since the coloring step is executed immediately after the extrusion cladding step, the temperature of the cladding heated to a high temperature in the extrusion cladding step can be reduced by the evaporation heat when the coloring agent used in the coloring step is dried. Therefore, in addition to suppressing the limitation in changing the color applied to the electric wire, the cladding is cooled in the coloring step so that the step for cooling the cladding can be reduced.

Further, the cladding heated to the high temperature in the extrusion cladding step is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding. Therefore, the dye or pigment is difficult to come off from the outer surface of the cladding. The electric wire thus formed can be used as the electric wire which is arranged in a motor vehicle. Further, since the cladding heated to the high temperature is colored, heating for drying is not required after the cladding has been colored using the coloring liquid or paint.

Further, since the cladding4at the high temperature is sprayed with the coloring agent, the cladding4does not suffer from adverse effects (reduction in the mechanical strength and surface corrugation) as compared with the case where the cladding is previously treated using known swelling agent, solvent, plastic agent, etc. before the coloring agent is sprayed.

In another embodiment of the present invention, in the coloring step, the outer surface of the cladding can be colored with a plurality of colors, and the color applied to the outer surface can-be changed. Therefore, the cladding can be colored with various colors which can be changed. Accordingly, in addition to suppressing the limitation in changing the color applied to the electric wire, the color applied to the cladding in the coloring step can be easily changed. This suppresses reduction in the electric wire manufacturing efficiency.

In another embodiment of the present invention, any position of the electric wire is measured to exchange the plurality of coloring portions. Therefore, the electric wire can be colored with a plurality of colors. In addition, without stopping the operation of manufacturing the electric wire temporarily, the color applied to the electric wire can be easily changed, and reduction in the electric wire manufacturing efficiency can be suppressed.

Further, any position of the electric wire can be measured. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified. Thus, reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, the upstream coloring portion is stopped, and when the electric wire moves over an interval between said coloring portions while an upstream coloring portion of the coloring portions is stopped, the downstream coloring portion thereof is operated. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified. Accordingly, reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, where the upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is operated, when the electric wire moves over an interval between said coloring portions, the downstream portion is stopped. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified. Accordingly, reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, the extrusion cladding unit of forming the cladding and the coloring unit of coloring the electric wire are individually provided. Therefore, by changing the color in the coloring step, the color applied to the electric wire can be easily changed.

In the extrusion cladding step, the cladding is coated with the non-color synthetic resin. Therefore, the product numbers (kinds of the color of the outer surface) of the electric wire which is obtained by the extrusion cladding unit can be reduced. Thus, the space for storing the electric wire and effort to manage the product numbers can be also reduced.

In the coloring unit, the outer surface of the non-colored cladding is colored. Therefore, even when the outer surface of the non-colored cladding is colored with the color having higher brightness than that of the outer surface, the non-colored resin can be hidden by the color adopted in the coloring unit. Therefore, in the coloring step, the electric wire can be colored with any color which can be changed without limit. Accordingly, the limitation when the color for coloring electric wire is changed can be removed.

In another embodiment of the present invention, since the coloring unit is arranged immediately after the extrusion cladding unit, the temperature of the cladding heated to a high temperature in the extrusion cladding unit can be reduced by the evaporation heat during coloring in the coloring unit. Therefore, in addition to the limitation of changing the color applied to the electric wire, the cladding can be cooled by the coloring unit so that the unit for cooling the cladding and the electric wire manufacturing apparatus can be miniaturized.

Further, the cladding heated to the high temperature in the extrusion cladding step is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding. Therefore, the dye or pigment is difficult to come off from the outer surface of the cladding. The electric wire thus formed can be used as the electric wire which is arranged in a motor vehicle. Further, since the cladding heated to the high temperature is colored, heating for drying is not required after the cladding has been colored using the coloring liquid or paint.

Further, since the cladding at the high temperature is sprayed with the coloring agent, the cladding does not suffer from adverse effects (reduction in the mechanical strength and surface corrugation) as compared with the case where the cladding is previously treated using known swelling agent, solvent, plastic agent, etc. before the coloring agent is sprayed.

In another embodiment of the present invention, the coloring unit includes a plurality of coloring portions and the exchanging portion. Therefore, by exchanging the coloring portions to operate in the coloring unit, the outer surface of the cladding can be colored with various colors. Thus, in addition to suppressing the limitation of changing the color applied to the electric wire, the color applied to the cladding in the coloring unit can be easily changed. Accordingly, reduction in the efficiency of manufacturing the electric wire can be suppressed.

In another embodiment of the present invention, the coloring unit includes the plurality of coloring portions. Therefore, the electric wire can be colored with the plurality of colors.

In addition, the exchanging means can exchange the coloring portions. Therefore, without temporarily stopping the coloring unit, i.e. electric wire manufacturing apparatus, the color applied to the electric wire can be easily changed. Thus, the color applied to the electric wire can be easily changed and reduction in the efficiency of manufacturing the electric wire can be suppressed.

Further, the measuring means can measure any position of the electric wire. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Accordingly, reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, the measuring means measures any position of the electric wire by measuring the information corresponding to a quantity of movement of the electric wire. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Accordingly, the color applied to the electric wire can be easily changed and reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, the exchanging means stops the upstream coloring portion and operates said downstream coloring portion when a quantity of movement of the electric wire measured by said measuring means becomes equal to the interval between said plurality of coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Accordingly, the color applied to the electric wire can be easily changed and reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, said exchanging means operates said upstream coloring portion while said downstream coloring portion is being operated, and stops said downstream coloring portion when a quantity of movement of the electric wire measured by said measuring means becomes equal to the interval between said plurality of coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Accordingly, the color applied to the electric wire can be easily changed and reduction in the material yield of the electric wire can be suppressed.

In another embodiment of the present invention, the coloring portion sprays the coloring agent in a sol state. Therefore, when the exchanging means exchanges the coloring portions, the color applied to the electric wire can be changed immediately. Therefore, the color applied to the electric wire can be changed more easily, and when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Accordingly, reduction in the material yield of the electric wire can be suppressed.

When the coloring portion is changed, the color applied to the electric wire can be immediately changed. Therefore, the interval between the coloring portions can be narrowed. Thus, the coloring unit, i.e. the electric wire manufacturing apparatus can be miniaturized.

In another embodiment of the present invention, the cladding heated to the high temperature by the extrusion cladding is colored. Thus, since the outer surface of the cladding is colored before the synthetic resin constituting the cladding is hardened, the dye of the coloring agent is liable to sink within the cladding, and the pigment of the paint is liable to bond to the outer surface of the cladding. Therefore, the dye or pigment is difficult to come off form the outer surface of the cladding. The electric wire thus formed can be used as the electric wire which is arranged in a motor vehicle.

In another embodiment of the present invention, any position is measured and the coloring portions are exchanged to color the outer surface. Therefore, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified, thereby further suppressing the reduction in the material yield of the electric wire.

In another embodiment of the present invention, an upstream coloring portion of said coloring portions is stopped, and when the electric wire is moved over an interval between said coloring portions while a downstream coloring portion is operated to color the outer surface. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Thus, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified, thereby further suppressing the reduction in the material yield of the electric wire.

In another embodiment of the present invention, the upstream coloring portion of the coloring portions is operated while a downstream coloring portion thereof is being operated, and the downstream coloring portion is stopped after the electric wire moves over an interval between the coloring portions. Therefore, when the coloring portions are exchanged, any overlapping portion of the first color and the second color can be avoided and the area not colored with both colors can be avoided. Thus, the boundary between the first area colored with the first color and the second area colored with the second color can be clarified, thereby further suppressing the reduction in the material yield of the electric wire.