JP7602433B2 - Mold Cooling Device - Google Patents

Description

This specification discloses a mold cooling device.

A coil coating forming device that forms an insulating coating on the coil end portion of a stator coil has been proposed that includes a mold having an annular recess on its upper surface into which a thermosetting resin is filled, and a spiral-shaped IH coil arranged on the lower surface of the mold (see, for example, Patent Document 1). In this device, the recess of the mold is filled with thermosetting resin, the coil end portion is immersed in the filled thermosetting resin, and a high-frequency alternating current is applied to the IH coil to heat the mold, thereby hardening the thermosetting resin and forming an insulating coating on the coil end portion.

JP 2019-129605 A

When molding using thermosetting resins on a production line, the mold must be repeatedly heated and cooled in order to be used repeatedly, and a mold cooling device that uses, for example, a copper heat sink can be considered. However, over time, contact marks (dents) can appear on the heat sink due to contact with the mold, and the adhesion of the mating surfaces between the mold and heat sink can deteriorate, resulting in the formation of an air layer that can reduce cooling efficiency. In addition, the use of a dedicated heat sink leads to increased costs.

The primary objective of the mold cooling device disclosed herein is to provide a mold cooling device that can efficiently cool molds while reducing costs.

The mold cooling device disclosed herein employs the following measures to achieve the above-mentioned primary objective:

The mold cooling device of the present disclosure is
A mold cooling device that is used together with a resin molding device that fills a mold having an annular cavity with a thermosetting resin and heats the mold, and that cools the mold,
The gist of the invention is that the cooling pipe is configured by bending a metal tube into a spiral shape and is arranged so that one surface in the axial direction of the central axis of the spiral is in contact with the surface of the mold, and the cooling pipe cools the mold by heat exchange with a cooling liquid flowing inside.

In the mold cooling device disclosed herein, a metal tube is bent into a spiral shape, and one surface in the axial direction of the central axis of the spiral is arranged to contact the surface of the mold, and the cooling tube is provided to cool the mold by heat exchange with the cooling liquid flowing inside. When a heat sink is used as the mold cooling device, contact marks are generated due to contact between the mold and the heat sink over time, and the adhesion of the mating surfaces of the mold and the heat sink deteriorates, which may result in a decrease in cooling efficiency due to the presence of an air layer. In contrast, in the mold cooling device disclosed herein, the elastic effect of the spiral shape of the cooling tube can increase the adhesion with the mold, thereby improving the cooling efficiency. In addition, the adhesion between the cooling tube and the mold can be maintained even with long-term use, so the decrease in cooling efficiency can be suppressed. Furthermore, since a general-purpose metal tube can be used as the cooling tube, costs can be reduced compared to those using dedicated heat sinks.

FIG. 1 is a schematic diagram of a stator for an electric motor. 5 is an explanatory diagram showing an insulating film forming step of forming an insulating film on a coil end portion of a stator coil. FIG. FIG. 2 is a cross-sectional perspective view of a mold used in an insulating coating forming step. 5 is an explanatory diagram showing a state in which a coil end portion of a stator coil is immersed in a thermosetting resin filled in a mold. FIG. FIG. 2 is a front view of a mold cooling device used in the mold cooling process. FIG. 2 is a cross-sectional perspective view of a mold and a mold cooling device. FIG. 10 is an explanatory diagram showing the cooling of a mold using a mold cooling device of a comparative example. FIG. 2 is an explanatory diagram showing the state of die cooling using the die cooling device of the present embodiment.

Next, we will explain how to implement the present invention using examples.

Figure 1 is a schematic diagram of a stator for an electric motor. The stator 10 for an electric motor is combined with a rotor to form a three-phase AC generator motor, and is used, for example, as a motor or generator for driving electric vehicles and hybrid vehicles. As shown in Figure 1, the stator 10 includes a stator core 12 and multiple stator coils 15 (U-phase coil, V-phase coil, and W-phase coil).

The stator core 12 is constructed by laminating multiple non-oriented electromagnetic steel sheets formed into an annular shape, for example by pressing, and has multiple teeth that protrude radially inward at predetermined intervals in the circumferential direction so that multiple slots are formed on the inner circumference.

The multiple stator coils 15 are formed by electrically joining multiple segment conductors 14. The segment conductors 14 are made of a highly conductive metal such as copper, and are generally U-shaped conductors with a rectangular cross section and an insulating coating made of enamel resin or the like formed on the surface. The insulating coating is removed from the end 14e of each segment conductor 14, since it is to be joined to the end 14e of another segment conductor 14. One end 14e of each segment conductor 14 is inserted from one end side to the other end side in the axial direction into the corresponding slot of the stator core 12, and the other end 14e is inserted from one end side to the other end side in the axial direction into another slot spaced circumferentially from the slot, and the end 14e of each segment conductor 14 protruding outward from the other end side in the axial direction of the slot is welded and joined to the end 14e of the corresponding other segment conductor 14, thereby forming multiple stator coils 15, i.e., U-phase coils, V-phase coils, and W-phase coils.

An insulating film is formed on the coil end portion 15e of the stator coil 15 to insulate the welded portion. Figure 2 is an explanatory diagram showing the insulating film forming process in which an insulating film is formed on the coil end portion of the stator coil using a die 20 on a production line. As shown in Figure 3, the die 20 has an annular cavity 22 formed on the upper surface. The annular cavity 22 has a diameter corresponding to the diameter of the coil end portion 15e and a depth corresponding to the amount of protrusion of the coil end portion 15e.

In the insulating film forming process, first, a resin filling process is performed in which the cavity 22 of the mold 20 is filled with thermosetting resin (S100). Next, the coil end portion 15e of the stator coil 15 is immersed in the cavity 22 filled with the thermosetting resin (S110). Then, a heating process is performed in which the mold 20 is heated and the thermosetting resin is hardened (S120). The heating process is a process in which the coil end portion 15e of the coil 15 is molded with the thermosetting resin by the mold heating device 25. As shown in FIG. 4, the mold heating device 25 is disposed on the underside of the mold 20 and has an IH coil. The IH coil is a flat, spiral coil, and when a high-frequency alternating current is applied, eddy currents are generated in the mold 20 by magnetic lines (electric field), and the mold 20 is heated by Joule heat.

After the coil end portion 15e is molded with thermosetting resin by the heating process, the coil end portion 15e is released from the mold 20 (S130), and the mold 20 is cooled by the mold cooling device 30 in a cooling process (S140). The cooling process is a process for returning the temperature of the mold 20 to a temperature suitable for filling with thermosetting resin before the next resin filling process after the heating process is completed when the mold 20 is used repeatedly in the production line. FIG. 5 is a front view of the mold cooling device used in the cooling process, and FIG. 6 is a cross-sectional perspective view of the mold and the mold cooling device. As shown in the figure, the mold cooling device 30 includes a cooling pipe 31 arranged to contact the lower surface of the mold 20, and a support member 32 that supports the cooling pipe 31 from the opposite side to the mold 20. The cooling pipe 31 is a metal pipe that is flexible and has excellent thermal conductivity, such as copper, aluminum, copper alloy, or aluminum alloy, and is configured as a metal pipe that is bent in a spiral shape on the same plane. The cooling pipe 31 is arranged so that one surface (upper surface) in the axial direction of the central axis of the spiral is in contact with the lower surface of the mold 20, and a cooling liquid (cooling water) is supplied from one open end of the cooling pipe 31 while in contact with the mold 20, thereby cooling the mold 20 by heat exchange with the cooling water flowing inside. The support member 32 is a flat elastic body made of heat-resistant resin such as heat-resistant rubber, and supports the cooling pipe 31 from the other surface (lower surface) in the axial direction of its central axis so that the cooling pipe 31 is pressed against the mold 20 by elastic force.

7 is an explanatory diagram showing the cooling of a mold using a mold cooling device of a comparative example, and FIG. 8 is an explanatory diagram showing the cooling of a mold using a mold cooling device of this embodiment. As shown in FIG. 7, the mold cooling device 20B of the comparative example is equipped with a copper heat sink 31B in which a water channel through which cooling water flows is formed and whose upper surface (mating surface) is machined to conform to the lower surface of the mold 20. In the mold cooling device 30B of the comparative example, the mating surface of the heat sink 31B is brought into contact with the lower surface of the mold 20 and cooling water is supplied to the water channel of the heat sink 31B, so that the heat of the mold 20 is transferred to the heat sink 31B to cool the mold 20. Since copper, which has high thermal conductivity but is flexible, is used as the material of the heat sink 31B, contact marks (dents) with the mold 20 may occur on the mating surface of the heat sink 31B due to long-term use, and the mold 20 may ride on the contact marks and deteriorate the adhesion with the heat sink 31B. In this case, the cooling efficiency is significantly reduced due to the air layer interposed between the mold 20 and the heat sink 31B.

In contrast, in the mold cooling device 30 of this embodiment, as shown in FIG. 8, the cooling pipe 31 is formed by bending a flexible metal pipe with excellent thermal conductivity into a spiral shape, and the elastic effect of the spiral shape of the cooling pipe 31 can increase the adhesion with the mold 20, thereby improving the cooling efficiency. In addition, since the adhesion can be maintained even with long-term use, the decrease in cooling efficiency due to long-term use can be suppressed. Furthermore, since a general-purpose metal pipe such as a copper pipe or an aluminum pipe can be used as the cooling pipe 31, costs can be reduced compared to the comparative example, which uses a dedicated heat sink.

Furthermore, in the mold cooling device 30 of this embodiment, the support member 32 that supports the cooling pipe 31 is made of a rubber elastic body. Therefore, as shown in FIG. 8, even if the mold 30 is tilted or has some unevenness, the elastic action of the spiral shape of the cooling pipe 31 and the elastic action of the material of the support member 32 allow the cooling pipe 31 to be properly attached to the mold 20, improving the cooling efficiency.

In the above-described embodiment, the support member 30 is made of a rubber elastic body, but this is not limited thereto. For example, the cooling pipe 31 may be supported by a plurality of springs so as to be pressed against the mold 20.

The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the invention.

The present invention can be used in the mold cooling device manufacturing industry.

10 stator, 12 stator core, 14 segment conductor, 14e end portion, 15 stator coil, 15e coil end portion, 20 mold, 21 cavity, 25 mold heating device, 30 mold cooling device, 31 cooling pipe, 32 support member.

Claims (4)

A mold cooling device that is used together with a resin molding device that fills a mold having an annular cavity with a thermosetting resin and heats the mold, and that cools the mold,
A cooling pipe is provided in which a metal pipe is bent in a spiral shape and a cooling liquid flows therethrough,
the die is cooled by bringing one surface of the cooling pipe in the central axis direction into contact with the surface of the die and flowing a cooling liquid through the cooling pipe;
Mold cooling device. The mold cooling device according to claim 1,
a support member formed of an elastic body and supporting the cooling pipe from the other surface side in the central axis direction;
Mold cooling device. The mold cooling device according to claim 2,
The elastic body is rubber.
Mold cooling device. The mold cooling device according to any one of claims 1 to 3,
The metal tube is made of copper, aluminum, a copper alloy, or an aluminum alloy.
Mold cooling device.

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