JPH03150114A - Method and apparatus for hardening resin of molded coil for electrical device - Google Patents

Abstract

PURPOSE:To prevent voids or cracks from developing in a molded coil and consequently improve its quality by a method wherein heat released from the part, which is far away from a resin inlet, of a cavity and given to a mold is checked by utilizing heat insulating member. CONSTITUTION:Under the condition that resin 27 is poured in a cavity 15, a coil 20 or four split coils 16 - 19 are energized in order to generate heat in the coil 20. Due to the generation of heat in the coil, the heat transmits from the coil 20 to the resin 27 and released from the resin 27 and given to a mold 11. At this time, the heat dissipated from the sin 27 at the lower part of the part, which is the farthest away from a resin inlet 15a, of the cavity 15 to the mold 11 is checked by heat insulating member 16. Thus, the temperature of the resin 17 at the lower part of the cavity becomes higher and the temperature of the resin 27 becomes gradually lower from that at said lower part to that at the resin inlet 15a. Accordingly, the resin 27 at said lower part firstly starts to harden and the resin 27 near the resin inlet 15a hardens lastly. Thus, stress is released at the resin inlet 15a, resulting in preventing the stress from remaining in the resin 27 as small as possible and allowing to preventing voids, cracks or the like from developing.

Description

[Detailed description of the invention]

[Objective of the invention] (Industrial field in Icheon) The present invention is an electric device that places a coil in a mold cavity, injects resin into the cavity from the resin injection port, and heats and hardens the resin. The present invention relates to a resin curing method for molded coils and a curing device therefor. (Prior Art) An example of a conventional resin curing device for molded coils for electrical equipment is shown in FIG. In FIG. 5, 1 is a mold, which includes a cylindrical mold member 2, a bottom mold member 3 that closes the lower opening of this mold member 2, and this bottom mold member 3.
It consists of a convex mold member 4 that is protruded from the center of the upper surface of the mold member 2 and extends along the axis of the mold member 2. The mold member 2 includes mold members 2a and 2 each having a semi-cylindrical shape. In the cavity 5 of such a mold 1, a plurality of, for example, four, divided coils 6 are arranged side by side in the axial direction. and,
A thermosetting resin is injected into the cavity 5 while the mold 1 and the split coil 6 are preheated. Thereafter, the mold 1 was housed in a hot air circulation type heating furnace (not shown) and uniformly heated to heat and harden the resin film. In the above-mentioned conventional structure, since the mold 1 is heated from the outside, the resin starts to harden from the part that is in contact with the mold 1, that is, the outer part, and the hardening of the central part is delayed. Also, the resin contracts when cured. For this reason, the central portion, which is delayed in curing, cures and shrinks in a sealed state where the outside is hardened, so that stress may remain in the central portion that has been completely cured, or the resin density may decrease. As a result, there was a drawback that cavities and cracks were formed in the molded coil after curing was completed. In order to avoid this, conventionally, the stress is reduced to the resin inlet part of the resin pipe, that is, the upper part 7a in FIG.
After curing is completed, the upper portion 7a is cut and discarded. However, with such a configuration, sufficient effects could not be obtained. As a configuration to solve the above drawbacks, Japanese Patent Application Laid-Open No. 49-6395
There is one shown in Publication No. 3. This configuration is shown in FIG. 6 and FIG. In FIGS. 6 and 7, four divided coils 6 are connected in series, and terminals 8.8 led out from both ends of the connected divided coils 6 are passed through the wall of the mold member 2. It is pulled out to the outside, and this terminal 8.8
is connected to power supply 9. Note that an insulating member 10 is interposed between the terminal 8 and the mold member 2 at 1rA1. In this configuration, a current i is applied to the split coil 6 to generate heat, thereby heating and hardening the resin film. In this case, the resin film begins to harden from the part that contacts the split coil 6, that is, from the central part, and the hardening progresses outward in sequence, so that no stress remains in the central part. (312fI to be solved by the invention) However, in the above configuration, since the outer part of the resin cover that contacts the mold 1 is cured later, sink marks etc. occur on the outer peripheral surface of the molded coil, which is a molded product. Therefore, the object of the present invention is to provide a molded coil for electrical equipment that can prevent cavities and cracks from forming in the molded coil and improve its quality. The present invention provides a resin curing method and a curing device.

[Structure of the invention]

(Means for Solving the Problems) The resin curing method for a molded coil for electrical equipment of the present invention includes:
A method in which a coil is placed in a cavity of a mold, a resin is injected into the cavity from the resin injection port, and the resin is heated and cured by applying electricity to the coil to generate heat. It is characterized in that heat is prevented from being released to the mold from a portion far away from the resin injection port. Further, in the curing device for a molded coil for electrical equipment of the present invention, a plurality of divided coils are arranged in a mold cavity, a resin is injected into the cavity from the resin injection port, and the resin is energized to the divided coils. The resin molding device is characterized in that a heat insulating member is provided in a portion of the cavity far away from the resin injection port to prevent heat from being released to the mold. (Function) According to the above means, when the coil is energized to generate heat, the heat is transmitted from the coil to the resin, and further, the heat is released from the resin to the mold. In this case, the heat insulating member prevents heat dissipation from the resin to the mold in a portion of the cavity that is far away from the resin injection port. For this reason, the temperature of the resin in a portion far away from the resin injection port increases, and the temperature of the resin gradually decreases from this portion toward the resin injection port. Therefore, the resin in the portion far away from the resin injection port begins to harden first, and the resin in the portion close to the resin injection port becomes a ribbon last. This can prevent stress from remaining in the resin as much as possible. (Example) An example of the present invention will be described below with reference to FIGS. 1 to 5. In FIG. 1, the mold 11 includes a mold member 12 having a substantially cylindrical shape, a bottom mold member 13 that closes the lower opening of the mold member 12, and a center portion of the upper surface of the bottom mold member 13. It is comprised of a convex mold member 14 that is provided in a protruding manner and extends along the axis of the mold member 12 . The mold member 12 includes mold members 12a and 12 each having a semi-cylindrical shape. In the cavity 15 of such a mold 11, there are a plurality of, for example, four divided coils 16.1? , 18°19
are arranged side by side in the axial direction. A coil 20 is constituted by these four divided coils 16, 17, 18, 19. Here, among the four divided coils 16 to 19,
Two split coils 16 and 17 disposed in the farthest part of the cavity 15 from the resin injection port 15a, for example, in the lower part of the cavity 15 in FIG. 1, are connected in series. The connected divided coils 16 and 17 are referred to as a lower coil 21 as shown in FIG. The terminals 21a and 21b are connected to a power source 22. Also,
Among the four divided coils 16 to 19, the resin injection port 15a
For example, 2IQ split coils 18 and 19 arranged in the upper part of the cavity 15 in FIG. 1 are connected in series. The connected divided coils 18 and 19 are referred to as upper coils 23 as shown in FIG.
The terminals 23a and 23b led out from both ends of the mold member 1
The terminals 23 a and 23 b are connected to the power source 22 through a through hole formed in the wall of the terminal 2 . In this case, the lower coil 21 and the upper coil 23 are connected in parallel to the power supply 22, and the upper coil 21 and the upper coil 23 are connected in parallel to the power supply 22.
For example, a variable resistor 2, which is a current control means, is connected to the overcurrent path 3.
4 is provided. This variable resistor 24 is 0 to -(
The resistance value (Ω) can be set. Note that an insulating member 25 is interposed between each of the terminals 21a, 21b, 2-3a, and 23b and the through hole of the mold member 12. Now, in the cavity 15 of the mold 11, the part farthest from the resin injection port 15a, for example, the inner bottom, is provided with an annular plate-shaped heat insulating material made of a material having a higher thermal resistance than the mold 11. A member 26 is provided. A thermosetting resin 27 is injected into the cavity 15 described above from the resin injection port 15g. Next, the effect of the above configuration will be explained in Figs. 3 and 4v! This will be explained with reference to J. With the resin 27 injected into the cavity 15, electricity is applied to the coil 20, that is, the four divided coils 16 to 19, to generate heat. Due to the heat generated by the coil 20,
Heat is transferred from the coil 20 to the resin 27, and further the resin 27
Heat is released from the mold 11 to the mold 11. At this time, the heat insulating member 2
6, the mold 11 is transferred from the lower resin 27, which is the part of the cavity 15 farthest from the resin injection port 158.
heat dissipation to is prevented. For this reason, the lower resin 2
As the temperature of 7 increases, the resin injection port 1 starts from this part.
The temperature of the resin 27 gradually decreases to 5M. Therefore, the resin 27 at the bottom begins to harden first, and the resin 27 near the resin injection port 15a hardens last. As a result, the stress is released from the resin injection port 15a, so it is possible to prevent the stress from remaining in the resin 27 as much as possible, to prevent cavities, cracks, etc. from forming in the mold fill. It is possible to prevent sink marks from occurring on the outer peripheral surface and improve quality. Incidentally, when applying current to the upper and lower coils 21 and 23, the same magnitude of current may be passed through each, but by appropriately setting the resistance value of the variable resistor 24, the current flowing through the lower coil 21 can be adjusted. Upper coil 23 compared to size
The amount of heat generated by the lower coil 21 may be greater than the amount of heat generated by the upper coil 23 by reducing the magnitude of the current applied to the lower coil 21 . As a result, the temperature of the lower resin 27 inside the cavity 15 becomes higher, and the temperature of the upper resin 27 inside the cavity 15 becomes lower. Heat release from the resin 27 in the lower part of the mold 11 to the mold 11 is prevented. Therefore, as shown in FIG. 3, there is a temperature distribution in which the temperature of the resin 27 at the part farthest from the resin injection port 15a increases, and the temperature of the resin 27 sequentially decreases from this part to the resin injection port 15a. You can definitely get it. Therefore, it is more reliably ensured that the portion of the resin 27 farthest from the resin injection port 20 begins to harden first, and the portion of the resin 27 closest to the resin injection port 20 hardens last. Incidentally, in the above embodiment, the temperature distribution when the heat insulating member 26 is not disposed inside the cavity 15 is shown in FIG. As is clear from FIG. 4, simply reducing the magnitude of the current flowing through the upper coil 23 compared to the magnitude of the current flowing through the lower coil 21 will lower the temperature at the bottom of the cavity 15. As a result, the resin at the bottom is not cured first. In addition, in the above embodiment, the divided coils 16 to 19 of 4a
Although the magnitude of the current flowing through the upper and lower two sets of divided coils is changed, the present invention is not limited to this.
The same magnitude of current may be applied to each divided coil, that is, the divided coils may be connected in series and treated as one undivided coil, and current may be applied to this one coil.

【Effect of the invention】

As is clear from the above description, the present invention uses a heat insulating member to prevent heat from being released into the mold from a portion of the cavity far away from the resin injection port, thereby preventing cavities or cracks in the mold coil. This has the excellent effect of preventing this from occurring and improving its quality. 4 Iil Qt Explanation of the Drawings Figures 1 to 4 show one embodiment of the present invention.
FIG. 1 is a longitudinal sectional view showing the electrical configuration, FIG. 2 is an electrical configuration diagram, and FIGS. 3 and 4 are diagrams showing the correspondence between the longitudinal section of the coil and temperature distribution. Further, FIG. 5 is a diagram equivalent to FIG. 1 showing a conventional configuration, and FIGS. 6 and 7 are diagrams equivalent to FIG. 1 and FIG. 2 showing different conventional configurations. In the drawing, 11 is a mold, 15 is a cavity, and 15a
20 is a resin injection port, 20 is a coil, 26 is a heat insulating member, and 27 is a resin. 1Im 11.11 1 I Figure 2Figure 5:46 Figure

Claims (1)

[Claims] 1. A method in which a coil is placed in a cavity of a mold, resin is injected into the cavity from the resin injection port, and the resin is heated and cured by applying electricity to the coil to generate heat. . A method of curing resin for a molded coil for electrical equipment, characterized in that a heat insulating member is used to prevent heat from being released from a portion of the cavity far away from the resin injection port to the mold. 2. A coil is placed in the cavity of the mold, resin is injected into the cavity from the resin injection port, and the resin is heated and cured by applying electricity to the coil to generate heat, in which the 1. A resin curing device for a molded coil for electrical equipment, characterized in that a heat insulating member for preventing heat release to the mold is provided in a portion far away from a resin injection port.