JP2019048946A - Cooling medium, cooling method, and wire cooling device - Google Patents

Abstract

To provide a cooling medium having high cooling performance, a cooling method using the cooling medium, and a wire cooling device using the cooling medium.SOLUTION: Due to that boron nitride is dispersed in water in a cooling medium L, it is possible to improve a heat transfer coefficient compared to water, and it is possible to efficiently cool a coated wire 100 by using the cooling medium L. Therefore, it is not necessary to enlarge a container 2 for storing the cooling medium L, or to complicatedly move (meandering move or the like) the coated wire 100 in the cooling medium L.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling medium, a cooling method, and a wire cooling device.

  Generally, in a production line for producing a coated electric wire in which a conductor is coated with a resin, a step of covering the conductor with a molten resin to form a coating, and then a step of cooling the coating is further performed. In this cooling step, the coated wire is cooled by moving it in the cooling water. In order to sufficiently cool the coated wire, it is necessary to secure a cooling time, and if the moving speed of the coated wire is increased to improve productivity, the distance for the coated wire to pass through the cooling water must be increased. As a result, there is a disadvantage that the size of the device is increased.

  Then, the electric wire coating apparatus which moves a covered electric wire meanderingly in cooling water is proposed (for example, refer patent document 1). In the wire covering device described in Patent Document 1, cooling is performed while meanwhile moving the coated wire in the cooling water (that is, reciprocating a plurality of times in a predetermined region), thereby increasing the distance for the coated wire to pass through the cooling water. While suppressing the increase in size of the device.

JP-A-8-153428

  However, in the wire covering device described in Patent Document 1, a mechanism for meandering movement of the coated wire is required, and the device is likely to be complicated. Therefore, when cooling the coated wire, it has been desired to use a cooling medium having high cooling performance. In addition, in the case of cooling an object other than the electric wire or in the case of not moving the object, it has been desired to use a cooling medium having high cooling performance in order to improve the cooling efficiency.

  An object of the present invention is to provide a cooling medium having high cooling performance, a cooling method using the cooling medium, and a wire cooling device using the cooling medium.

  The cooling medium of the present invention is characterized in that boron nitride particles are dispersed in water.

  The cooling method of the present invention is characterized in that the above-mentioned cooling medium and the object to be cooled are moved relative to each other.

  The wire cooling device according to the present invention comprises a container for containing the above-mentioned cooling medium, and moving means for moving the coated electric wire, and the moving means moves the coated electric wire along the longitudinal direction in the cooling medium by the moving means. It is characterized by

  According to the cooling medium of the present invention as described above, the dispersion of boron nitride in water makes it possible to improve the heat transfer coefficient as compared to water, and it is possible to cool the object to be cooled Performance can be improved.

  According to the cooling method of the present invention as described above, by using the cooling medium having high cooling performance as described above, even when the cooling medium and the cooling object are relatively moved, the cooling object is cooled. Efficiency can be improved.

  According to the electric wire cooling device of the invention of the present application as described above, the electric wire can be efficiently cooled by using the cooling medium having high cooling performance as described above.

It is a side view showing typically the electric wire cooling device concerning a 1st embodiment of the present invention. It is a side view which shows typically the cooling device concerning a 2nd embodiment of the present invention. It is a graph which shows distribution of the particle size of the boron nitride particle in the cooling medium of an Example. It is a graph which shows distribution of the particle size of the boron nitride particle in the cooling medium of another Example. It is a graph which shows distribution of the particle size of the boron nitride particle in the cooling medium of another Example. It is a graph which shows the viscosity of the cooling medium of an Example and a comparative example. It is a graph which shows the heat conductivity of the cooling medium of an Example and a comparative example. It is the schematic which shows the measuring apparatus for measuring the heat transfer coefficient of the cooling medium of an Example and a comparative example. It is a graph which shows the heat transfer coefficient of the cooling medium of an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described based on the drawings. In the second embodiment, the same components as those described in the first embodiment and components having the same functions as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

First Embodiment
The wire cooling device 1 of the present embodiment is, as shown in FIG. 1, provided on the downstream side of the coating forming portion 20 in the wire manufacturing apparatus 10, and is a container 2 for containing a cooling medium L; Moving means for moving the head along the longitudinal direction.

  The electric wire manufacturing apparatus 10 forms the coating 102 on the outer side of the conductor 101 by the coating forming portion 20 while moving the linear conductor 101 in a predetermined moving direction, and manufactures the coated electric wire 100. The coated wire 100 is to be cooled. The mechanism for moving the conductor 101 in the wire manufacturing apparatus 10 also functions as a moving means for moving the coated wire 100 in the wire cooling device 1.

  The container 2 is formed in a bowl shape extending along the longitudinal direction of the wire and opening upward. The container 2 is such that the coated wire 100 is introduced into the inside from the upstream end and the coated wire 100 is drawn out from the downstream end, and both ends are closed so that the cooling medium L does not leak There is. A supply unit that supplies a new cooling medium L to the container 2 and a discharge unit that discharges the cooling medium L from the container 2 may be provided.

  The electric wire cooling device 1 may include a plurality of containers 2 containing the cooling medium L, and may further include another container containing cooling water on the upstream side or the downstream side of the container 2.

  Here, the movement of the conductor 101 (and the covered wire 100) in the wire manufacturing apparatus 10 will be described. The conductor 101 fed to the coating forming portion 20 is covered with a molten insulating resin (for example, PP or PVC) to form the coating 102. Thereby, the coated electric wire 100 is formed, but in this state, the temperature of the coating 102 is high and is deformable. Therefore, the coating 102 is cooled and fixed by the wire cooling device 1.

  The sheathed electric wire 100 fed from the sheath forming portion 20 to the electric wire cooling device 1 is cooled along the longitudinal direction in the cooling medium L in the container 2 so that the sheath 102 is cooled. The moving speed of the coated electric wire 100 in the cooling medium L may be a speed that can sufficiently cool the coating 102 by the electric wire cooling device 1, depending on the melting point of the resin, the primary cooling time, the longitudinal dimension of the container 2, etc. Is set. The coated wire 100 cooled in the wire cooling device 1 is fed to a device for performing the post process.

  Here, the details of the cooling medium L will be described. The cooling medium L is a dispersion of boron nitride particles in water and contains a dispersant. The concentration of boron nitride particles in the cooling medium L is, for example, 1% by volume. The concentration of boron nitride particles in the cooling medium L is preferably 0.05 to 15% by volume, and more preferably 0.1 to 10% by volume. If the concentration of the boron nitride particles is in the range of 0.05 to 15% by volume, it is easy to improve the heat transfer coefficient of the cooling medium, and the viscosity does not easily increase. Further, the boron nitride particles are unlikely to remain on the surface of the coated electric wire 100, and there is no need to carry out post-processing such as cleaning. On the other hand, when the concentration of boron nitride particles is too low, it is difficult to improve the heat transfer coefficient of the cooling medium. Also, if the concentration of boron nitride particles is too high, the viscosity of the cooling medium tends to be high.

  The average particle size of the boron nitride particles is, for example, 0.7 μm. The average particle diameter of the boron nitride particles is preferably 0.03 to 5 μm, and more preferably 0.05 to 3 μm. Here, the boron nitride particles have a disk shape, and the average particle diameter means the diameter of the disk. When the average particle size of the boron nitride particles is in the range of 0.03 to 5 μm, the number of particles can be made an appropriate value when the concentration of the boron nitride particles is set to a value within the above range. It is easy to improve the heat transfer coefficient of the cooling medium, and the viscosity does not easily increase. On the other hand, when the average particle diameter of the boron nitride particles is too small, the viscosity of the cooling medium tends to be high because the number of particles is too large when the concentration of the boron nitride particles is set to a value within the above range. In addition, when the average particle diameter of the boron nitride particles is too large, the number of particles is too small when the concentration of the boron nitride particles is set to a value within the above range, so it is difficult to improve the heat transfer coefficient.

  The dispersant has a functional group that reacts with the edge of the boron nitride crystal. The boron nitride crystal has an amino group and a hydroxy group at the edge, and easily reacts with an acid and a base, respectively. As the dispersant, for example, a polymer compound (polycarboxylic acid ammonia salt or carboxymethyl cellulose) having a carboxyl group that reacts with an amino group may be used, or a polymer compound having an amino group that reacts with a hydroxy group (polyethyleneimine) May be used. By emitting ultrasonic waves to a cooling medium L containing such a dispersant, the boron nitride particles are crushed and dispersed in water.

  According to such an embodiment, the following effects can be obtained. That is, by dispersing boron nitride in water in the cooling medium L, the heat transfer coefficient can be improved compared to water, and by using such a cooling medium L, the coated electric wire 100 can be efficiently cooled. can do. Therefore, it is not necessary to enlarge the container 2 which accommodates the cooling medium L, or to move the coated wire 100 in the cooling medium L complicatedly (for example, meandering movement).

  Further, since the cooling medium L contains a dispersant, the boron nitride particles can be easily dispersed in water, and the heat transfer coefficient of the cooling medium L can be easily improved.

Second Embodiment
The cooling device 200 of this embodiment is comprised by the container which accommodates the cooling medium L, as shown in FIG. By immersing the object to be cooled 300 in the cooling medium L, the object to be cooled 300 is cooled. The cooling medium L is the same as that in the first embodiment. In the illustrated example, the object to be cooled 300 has a rectangular parallelepiped shape, but the object to be cooled 300 may be spherical or may be a coated electric wire as in the first embodiment, and an appropriate shape may be provided. As long as it has it. The object to be cooled 300 is stationary in the cooling medium L, but the temperature of the object to be cooled 300 before cooling is higher than the temperature of the cooling medium L, so natural convection occurs as shown by the arrows in the figure. .

  According to such an embodiment, the following effects can be obtained. That is, as in the first embodiment, by using the cooling medium L in which boron nitride is dispersed in water, the object to be cooled 300 can be cooled efficiently.

  The present invention is not limited to the first embodiment and the second embodiment, but includes other configurations and the like that can achieve the object of the present invention, and the following modifications and the like are also included in the present invention. included.

  For example, in the first embodiment, the concentration of the boron nitride particles is preferably 0.05 to 15% by volume, and the average particle diameter of the boron nitride particles is preferably 0.03 to 5 μm, The concentration and average particle size of the boron nitride particles are not limited to these ranges. The concentration and average particle diameter of the boron nitride particles may be any suitable value according to the moving speed of the coated wire 100, the dimensions of the container 2, the amount (water level) of the cooling medium L, and the like.

  In the first embodiment, the cooling medium L contains the dispersant. However, for example, when the concentration of the boron nitride particles is low, or when the moving speed of the coated wire 100 is high and the flow tends to occur in the cooling medium The cooling medium may not contain the dispersing agent under the condition that the boron nitride particles are easily dispersed.

  Besides, the best configuration, method and the like for carrying out the present invention are disclosed in the above description, but the present invention is not limited to this. That is, although the present invention has been particularly illustrated and described primarily with respect to particular embodiments, it should be understood that the present invention may be configured relative to the above-described embodiments without departing from the scope of the inventive concept and object. Those skilled in the art can make various modifications in materials, quantities, and other detailed configurations. Therefore, the description with the above-described disclosure of the shape, the material, etc. is exemplarily described for facilitating the understanding of the present invention, and is not intended to limit the present invention. The description in the name of a member from which some or all of the limitations such as the limitation have been removed is included in the present invention.

[Evaluation of particle size]
The average particle diameter of the boron nitride particles was evaluated using a scattering particle size distribution analyzer manufactured by Horiba, Ltd. For each example described later, ZSA-200 (particle diameter 0.05 μm), ZSA-20 (particle diameter 0.7 μm), and ZSA-5 (particle diameter 3 μm) manufactured by Zix Industrial Co., Ltd. were used. The measurement results (particle size distribution) of these particle sizes are shown in FIGS.

[Viscosity measurement result]
The viscosities of the cooling media of Examples and Comparative Examples were measured. For measurement, a B-type viscometer manufactured by Eiko Seiki Co., Ltd. was used. A dispersion of 1% by volume of boron nitride particles in water is used as a cooling medium of Example 1, and a dispersion of 0.1% by volume of boron nitride particles in water is set as a cooling medium of Example 2, 1 volume in water % Dispersed in alumina particles is used as the cooling medium of Comparative Example 1, and 0.1% by volume of alumina particles dispersed in water is used as the cooling medium in Comparative Example 2, and distilled water is used as the cooling medium in Comparative Example 3 did.

  At this time, the cooling medium of Examples 1 and 2 contains ammonium polycarboxylate as a dispersing agent, and is crushed by ultrasonic radiation. The same applies to the following embodiments. Moreover, the average particle diameter of the boron nitride particle | grains in the cooling medium of Example 1, 2 is 3 micrometers. The measurement results of the viscosity are shown in FIG. In the graph of FIG. 6, the horizontal axis represents the shear rate, and shows the shear rate characteristic of the kinematic viscosity.

  Although the viscosity of the coolant of Examples 1 and 2 was slightly higher than that of the coolant of Comparative Example 3 (distilled water), the viscosity was higher than that of the coolant of Comparative Examples 1 and 2 containing alumina particles of the same concentration. It got lower.

[Thermal conductivity measurement result]
The thermal conductivity of the cooling media of Examples and Comparative Examples was measured. The cooling media of Examples 3A to 3D are respectively dispersions of 0.001% by volume, 0.01% by volume, 0.2% by volume, and 2% by volume of boron nitride particles in water. The average particle diameter of the boron nitride particles in the cooling medium of Examples 3A to 3D is 3 μm. The cooling media of Comparative Examples 4A to 4D are obtained by dispersing 0.001% by volume, 0.01% by volume, 0.2% by volume, and 2% by volume of alumina particles in water. The measurement results of the thermal conductivity are shown in FIG.

  In the cooling media of Examples 3A to 3D, the thermal conductivity was higher than the cooling media of Comparative Examples 4A to 4D having the same concentration.

[Result of measurement of forced convection heat transfer coefficient]
The thermal conductivity of the cooling media of Examples and Comparative Examples was measured. The cooling medium of Example 4 is a dispersion of 1% by volume of boron nitride particles in water, and the average particle diameter of the boron nitride particles is 0.7 μm. The cooling medium of Comparative Example 5 is distilled water. The heat transfer coefficients of the cooling media of Example 4 and Comparative Example 5 were measured using the measuring device 400 shown in FIG.

  The measuring device 400 includes a measuring unit 401, a thermostatic bath 402, a diaphragm type liquid feed pump 403, a flow meter 404, and a heater power supply 405. The measuring unit 401 is configured of an acrylic tube 406 having a length of 1000 mm and an inner diameter of 35 mm, and a pseudo electric wire 407 accommodated in the acrylic tube 406. The pseudo electric wire 407 is constituted of a heater wire 408 with an outer diameter of 1.6 mm, both ends of which are connected to the heater power supply 405, and a PVC tube coating 409 with an outer diameter of 7 mm provided outside the heater wire 408. In the dummy wire 407, the temperature was measured by a thermocouple between the heater wire 408 and the PVC tube coating 409 and at a position of 1 mm from the outside of the PVC tube coating 409.

  In the measuring device 400, the cooling medium is fed by the liquid feeding pump 403, and the cooling medium is passed inside the acrylic pipe 406 and outside the dummy wire 407. At this time, by applying a voltage to the heater wire 408 by the heater power supply 405 and energizing the same, the pseudo electric wire 407 was heated to a predetermined temperature. The cooling medium that has passed through the acrylic pipe 406 is cooled to a predetermined temperature by the thermostatic bath 402 and returns to the liquid feed pump 403 again.

  The coated wire 100 moves in the electric wire cooling device 1 according to the first embodiment, while the measuring device 400 simulates a state in which the electric wire and the cooling medium move relative to each other by sending (moving) the cooling medium. did. By controlling the feed pump 403 to change the main flow velocity of the cooling medium, the Reynolds number was changed to measure the heat transfer coefficient. The results are shown in FIG. In FIG. 9, the horizontal axis is shown by converting the Reynolds number into the flow velocity.

  In any of the cooling media of Example 4 and Comparative Example 5, the heat transfer coefficient also increased as the flow velocity increased. Moreover, the heat transfer coefficient tended to be higher in the cooling medium of Example 4 than in the cooling medium of Comparative Example 5 at any flow rate. That is, for the cooling medium of Example 4, the improvement of the cooling performance was observed in forced convection.

[Heat transfer coefficient measurement result at low Reynolds number]
The thermal conductivity of the cooling media of Examples and Comparative Examples was measured. The cooling media of Examples 5A to 5D were obtained by dispersing 0.001, 0.01, 0.2, and 0.25% by volume of boron nitride particles in water, respectively, and the average particle diameter of the boron nitride particles was as follows: It is 3 μm. The cooling media of Comparative Examples 6A to 6D are respectively dispersions of 0.001, 0.01, 0.2, and 0.25% by volume of alumina particles in water. The cooling medium of Comparative Example 7 is distilled water. The cooling mediums of Examples 5A to 5D and Comparative Examples 6A to 6D are placed in a 500 mL beaker, and a polypropylene test piece (20 × 20 × 20 mm) heated to 100 ° C. is placed therein, and the magnetic stirrer is operated at low speed. It was operated and stirred. The heat transfer coefficient was determined from the temperature change of the polypropylene test piece at this time. The flow rate and the Reynolds number were determined from the results of the same experiment using the cooling medium (distilled water) of Comparative Example 7. At this time, the flow velocity of the cooling medium was 0.211 × 10 ⁻⁴ m / s. This simulates the state of cooling the object to be cooled by natural convection as in the second embodiment. The results are shown in Table 1.

  The heat transfer coefficient of the cooling media of Examples 5A to 5D is higher than that of the cooling media of Comparative Examples 6A to 6D in which the alumina particles having the same concentration are dispersed, and the heat conductivity is higher than that of the cooling medium (distilled water) of Comparative Example 7 Became high. That is, for the cooling media of Examples 5A to 5D, the improvement of the cooling performance was observed in a state where natural convection was simulated.

L Cooling medium 100 Coated electric wire 300 Cooling object 1 Electric wire cooling device 2 container

Claims (7)

  A cooling medium characterized in that boron nitride particles are dispersed in water.   The cooling medium according to claim 1, wherein the concentration of the boron nitride particles is 0.05 to 15% by volume.   The average particle diameter of the said boron nitride particle | grains is 0.03-5 micrometers, The cooling medium of Claim 1 or 2 characterized by the above-mentioned. A dispersant for dispersing the boron nitride particles in water;
The said dispersing agent has a functional group which reacts with the edge part of a boron nitride crystal | crystallization, The cooling medium of any one of the Claims 1-3 characterized by the above-mentioned.   A cooling method characterized by relatively moving the cooling medium according to any one of claims 1 to 4 and an object to be cooled.   The cooling method according to claim 5, wherein the coated electric wire as the object to be cooled is moved along the longitudinal direction in the cooling medium. A container containing the cooling medium according to any one of claims 1 to 4 and moving means for moving a coated wire.
A wire cooling device characterized in that the coated wire is moved along the longitudinal direction in the cooling medium by the moving means.

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