JPH03190115A - Hardening method of mold coil resin for electric machine and hardening device - Google Patents

Abstract

PURPOSE:To prevent generation of cavities and cracks on a mold coil, and the resin on the quality-improved mold coil for an electric machine is hardened by a method wherein the temperature of a mold is set lower than the coil, the temperature of the mold is raised on the part far away from the pouring hole of resin, and the temperature is made to go down as going nearer to the resin pouring hole. CONSTITUTION:When the resin 17 in a cavity 12 is going to be hardened by heating, the temperature of a mold 11 is set lower than that of a coil 13, the temperature of the lower mold 15 of the mold 11 is set lower than that of the upper mold 14, and as the temperature of the mold 11 is set in such a manner that it becomes lower as going deeper in the mold, the resin 17 of the coil 13 begins to harden, then the resin 17 is hardened successively as going nearer to the resin-pouring inlet, and the resin 17 of the part close to the resin- pouring inlet is hardened lastly. As a result, stress can be prevented from remaining in the resin 17, and the generation of cavities and cracks in the mold coil can also be prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention involves placing a coil, which is an object to be molded, in a mold cavity, and then injecting resin into the cavity. The present invention relates to a resin curing method for a molded coil for electrical equipment, which is cured by heating, and a curing apparatus therefor.

(Prior Art) Molded coils for electrical equipment, such as transformers or rotating electric machines, are manufactured by placing the coil, which is the object to be molded, in a mold.
It is manufactured by injecting resin into a mold and heating the resin to harden it. In this case, when curing the resin injected into the mold, it is desirable to harden from the center of the resin outward in order to reduce stress remaining inside the resin after curing.

Therefore, the configuration shown in Japanese Patent Publication No. 40-18894 has been conventionally provided. This configuration is shown in FIG.

In FIG. 2, a coil 2 is placed inside a container 1 which is a mold, a resin 3 is injected into the container 1, and a current is passed through the coil 2 from a power source 4 to generate heat. is heated from the center to harden it. In this configuration, the resin 3 starts to harden from the part that contacts the coil 2, that is, from the center part, and the hardening progresses outward in order, so that no stress remains in the center part, and there is no shrinkage due to curing and shrinkage of the resin. , voids are less likely to occur. Furthermore, since the resin 3 is directly heated by the coil 2, thermal efficiency is improved and the time required for curing can be shortened.

(Problems to be Solved by the Invention) In the above conventional configuration, the resin inside the coil 2 and the coil 2
The resin near the periphery will harden more quickly. but,
The resin in the bottom 5 portion of the container 1 is difficult to heat and hardens slowly. According to experiments, when a resin is injected which is semi-cured by heating at 100° C. for 3 hours, the resin in the bottom portion 5 does not gel even if the coil 2 is heated with electricity for 15 hours with the above configuration. For this reason, while the resin inside the coil 2 is in a cured state, the resin in the bottom portion 5 is not in a gelled state, resulting in an unbalanced state of curing progress.

Due to this unbalance, the cured resin has a disadvantage in that its crack resistance decreases, or its strength against tension, bending, etc. decreases.

In order to solve this problem, a configuration can be considered in which a current is passed through the coil to generate heat, and a mold is housed in a heating furnace to heat the resin from the outside.

However, with this configuration, since the resin at the resin injection port hardens quickly, there are disadvantages in that stress remains inside the resin, the resin density decreases, and sink marks occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a resin for molded coils for electrical equipment that can prevent cavities and cracks from forming in molded coils, prevent unbalanced curing progress of the resin, and improve the quality of the resin. The present invention provides a curing method and a curing device.

[Configuration 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, which is an object to be molded, 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 hardened by applying electricity to the coil to generate heat. The mold is heated so that the temperature is high in a part far from the resin injection port and gradually lowers from this part to the resin injection port, and the temperature of the mold is lower than the temperature of the coil. The present invention is characterized in that energization of the coil or heating of the mold is controlled.

Further, in the resin curing device for a molded coil for electrical equipment of the present invention, a coil as a molded object is placed in a mold cavity, a resin is injected into the cavity from the resin injection port, and the resin is applied to the molded coil. In a device that heats and cures by applying electricity to generate heat, heating the mold so that the temperature of the mold is high in a portion far away from the resin injection port and gradually lowers from this portion toward the resin injection port. and a first temperature detection means for detecting the temperature of a portion of the mold far away from the resin injection port, and based on the voltage value between the terminals of the coil and the current value of the current flowing through the coil. a second temperature detection means for detecting the temperature of the coil from the resistance value of the coil; The mold is characterized in that a control means is provided for controlling energization of the coil or heating of the mold so that the temperature of the mold becomes low.

(Function) According to the above means, the temperature of the mold is set to be lower than the temperature of the coil, and the temperature of the mold is raised in a part far away from the resin injection port, and from this part to the resin injection port sequentially. Since the temperature of the resin is set to be low, the temperature of the resin in the part that contacts the coil, that is, the center part, is the highest, and then
The temperature of the resin at a portion farthest from the resin injection port becomes high, while the temperature of the resin at a portion close to the resin injection port becomes low. Therefore, the resin in the center begins to harden first, and then the resin in the parts far away from the resin injection port hardens.
Finally, the resin near the resin injection port begins to harden. This can prevent stress from remaining in the resin. Since the mold is heated at the same time as the coil generates heat, the inside of the mold cavity is evenly heated as a whole, and unlike the conventional method, there is no particular delay in curing of a portion of the resin.

(Example) An example of the present invention will be described below with reference to FIG.

In FIG. 1, inside the cavity 12 of the mold 11 is a coil 1 for an electrical device such as a transformer or a rotating electric machine.
3 is placed. This coil 13 is made up of, for example, four divided coils connected in series. The mold 11 is composed of an upper mold 14 and a lower mold 15.
A resin injection port 16 is provided in the clay wall portion 4 in a penetrating manner.

A resin 17 is injected into the cavity 12 of the mold 11 through the resin injection port 16.

This resin 17 is, for example, an acid anhydride-curable bisphenol A epoxy resin. Inside the upper mold 14,
An upper heater 18 serving as a heating means is buried, and an upper temperature sensor 19 is located near the cavity 12.
is buried. The temperature of the upper mold 14 is detected by this upper temperature sensor 19 . A lower heater 20 serving as a heating means is embedded inside the lower mold 15, and a lower temperature sensor 21, for example, serving as a first temperature detecting means is embedded in a portion close to the cavity 12.

The temperature of the lower mold 15 is detected by the lower temperature sensor 21 .

Further, the lead wires 13a and 13a led out from the coil 13 are connected to lead terminals 22 and 22 provided penetratingly through the earthen wall portion of the upper mold 14. These lead-out terminals 22 and 22 include a rectifier 23 and a power regulator 24.
A power source 25 is connected via the power source 25. This power regulator 2
4 is configured by, for example, connecting thyristors in antiparallel, and controls the phase of the AC power from the power source 25 to supply the rectifying bag rt.
The heat generation output of the coil 13 is adjusted by adjusting the input power of L23 and thereby controlling the magnitude of the current flowing through the coil 13. The rectifying device 23 has a built-in filter and the like for reducing ripples.

Here, 26 is a voltage detection element equipped with a voltage divider, which detects the voltage between the terminals of the coil 13 and outputs a voltage detection signal corresponding to the voltage value. Reference numeral 27 denotes a current detection element equipped with a current shunt, which is interposed in the current-carrying path of the coil 13, detects the current flowing through the coil 13, and outputs a current detection signal corresponding to the current value. Each detection signal from the voltage detection element 26 and current detection element 27 is applied to the CPU 29 via an interface circuit 28. This CPU2
9 has a function as a second temperature detection means and a control means. The CPU 29 receives the voltage detection signal and current detection signal from the voltage detection element 26 and the current detection element 27, calculates the instantaneous resistance value of the coil 13, and calculates a predetermined temperature according to the material of the coil 13 from this resistance value. The temperature of the coil 13 is calculated according to a conversion formula.

On the other hand, the upper heater 18 of the upper mold 14 and the lower mold 15
The lower heater 20 is connected to a power source 25 via a power regulator 30.
is connected. Like the power regulator 24, this power regulator 30 is configured by connecting Cyrisks in antiparallel, and controls the phase of the AC power from the power source 25 to adjust the input power of the heater 18.20. Heater 18, 2
The heat generation output of the heaters 18 and 20 is adjusted by controlling the magnitude of the current flowing through the heaters 18 and 20. Further, each detection signal from the upper temperature sensor 19 and the lower temperature sensor 21 is provided to the CPU 29 via the interface circuit 28.

The CPU 29 then provides a control signal to the power regulator 24 via the interface circuit 31, and the power regulator 24 adjusts the heat generation output of the coil 13. At the same time, the CPU 29 provides a control signal to the power regulator 30 via the interface circuit 31, and the power regulator 30 adjusts the heat output of the heaters 18 and 20. The CPU 29 sends a control signal to the temperature display device 32 and the temperature recorder 33 via the interface circuit 31, and displays the temperature of the coil 13 and the upper metal plate calculated as described above to the temperature display device 32 and the temperature recorder 33. The temperature of the mold 14 and the temperature of the lower mold 15 are displayed and recorded.

Next, the operation of the above configuration will be explained.

First, with respect to the coil 13 before it is housed in the cavity 12 of the mold 11, the ambient temperature of the place where the coil 13 was placed is detected by a temperature sensor (not shown), and this temperature is stored as the initial temperature of the coil 13. . continue,
The coil 13 is housed in the cavity 12 of the mold 11, and the coil 13 is connected to a power supply 25, a power regulator 24, and a rectifier 23.
A current is passed through the . Immediately after this accommodation, voltage detection element 2
6 and the current detection element 27, the voltage value between the terminals of the coil 13 and the current value of the current flowing through the coil 13 are detected, and based on these, the initial resistance value of the coil 13 is calculated and stored. After that, the resin 17 is injected into the cavity 12 and a current is passed through the coil 13 to form the coil 13.
Heat is generated to start curing the resin 17 by heating. Note that after the start of energization of the coil 13, the resistance value R of the coil 13 is calculated every minute, for example, from the voltage value between the terminals of the coil 13 and the current value of the current flowing through the coil 13, and this resistance value R and The temperature t of the coil 13 is calculated using the initial temperature of the coil 13, the initial resistance value of the coil 13, and a temperature conversion formula suitable for the material of the coil 13. Here, coil 1
For material No. 3, the operator must use the CPU 29 before curing begins.
Set to .

In this case, the CPU 29 determines that the temperature of the coil 13 reaches a predetermined temperature, for example, 100°C, that is, the detected temperature t of the coil 13
When the temperature rises to a predetermined temperature, the power regulator 2
4, the heating output of the coil 13 is lowered and heating control is performed to maintain the predetermined temperature. On the other hand, the CPU 29 sets the temperature of the upper mold 14 to, for example, 80°C and the temperature of the lower mold 15 to, for example, 85°C based on the detection signals from the upper temperature sensor 19 and the lower temperature sensor 21. The heater 18,
Adjust the heat output of 20. As a result, the temperature of the mold 11 is set lower than the temperature of the coil 13, and the temperature of the lower mold 15 of the mold 11 is set lower than the temperature of the upper mold 14, that is, the temperature of the mold 11 is set lower than the temperature of the coil 13. The temperature is set so that it becomes high in a portion far away from the resin injection port 16 and gradually decreases from this portion toward the resin injection port 16. In such a temperature setting state, the resin 17 in the coil 13 portion, that is, the center portion, begins to harden first, and then the resin 17 in the portion far away from the resin injection port 16 hardens.
Finally, the resin 17 near the resin injection port 16 begins to harden. Additionally, as the resin 17 heat-cures,
The calculated temperature of the coil 13, the temperature of the upper mold 14, and the temperature of the lower mold 15 are displayed on the temperature display device 32 and recorded on the temperature recorder 33. When the curing of the resin 17 is completed, the output of the power regulators 24 and 30 is stopped, and the heat generation of the coil 13 and the heaters 18 and 20 is stopped.

According to this embodiment having such a configuration, when heating and curing the resin 17 in the cavity 12, the temperature of the mold 11 is set to be lower than the temperature of the coil 13, and
In the mold 11, the temperature of the lower mold 15 is changed to the upper mold 14.
In other words, the temperature of the mold 11 was set to be higher in the part far away from the resin injection port 16 and to be lowered sequentially from this part to the resin injection port 16.
The resin 17 in the coil 13 portion, that is, the center portion, begins to harden first, then the resin 17 in the portion far away from the resin injection port 16 hardens, and finally the resin 17 in the portion close to the resin injection port 16 hardens. become.

Therefore, stress can be prevented from remaining in the resin 17, and cavities and cracks can be prevented from forming in the molded coil. In addition, while making the coil 13 generate heat, the mold 11
That is, since the upper mold 14 and the lower mold 15 are heated, the inside of the cavity 12 of the mold 11 is evenly heated as a whole, so that the curing of the resin 3 in the bottom 5 portion of the container 1 is particularly delayed. Unlike the conventional method (see FIG. 2), the curing of the resin 17 proceeds smoothly, preventing the curing progress from becoming unbalanced, and improving the quality of the molded coil.

According to experiments, when an acid anhydride-curable bisphenol A epoxy resin is used as the resin 17 and the resin 17 is heated in a heating furnace, semi-curing is completed by heating at 85°C for 4 hours. On the other hand, in the above example, if the temperature of the coil 13 is set to 100°C, the temperature of the upper mold 14 to 80°C, and the temperature of the lower mold 15 to 85°C, semi-curing is completed in about 2.5 hours. .

By the way, in the conventional configuration in which the resin is heated and cured by applying electricity to the coil, if the coil generates heat at a constant output, the temperature of the resin may become too high due to the curing heat generated when the resin is cured. In this case, there is a disadvantage that the strength characteristics of the resin after curing deteriorate. On the contrary,
In the above embodiment, the temperature of the coil 13 is set to a predetermined temperature, for example, 1.
Since the heat output of the coil 13 is controlled so that the temperature is 00° C., even if curing heat is generated when the resin 17 is cured, the temperature of the resin 17 can be prevented from becoming too high due to the curing heat. Therefore, the quality of the resin 17 after curing can be further improved.

In the above embodiment, the temperature of the mold 11 is higher than the temperature of the coil 13.
That is, when setting the temperature of the upper mold 14 and the lower mold 15 to be lower, the temperature of the upper mold 14 is set within a range of 15±7°C than the temperature of the coil 13, and the temperature of the lower mold 15 is set lower than the temperature of the coil 13. Set within a range of 10±7℃ from the temperature in 13,
In addition, by setting the temperature of the lower mold 15 higher than the temperature of the upper mold 14, the above-mentioned effects can be obtained.

[Effects of the Invention] As is clear from the above description, the present invention sets the temperature of the mold to be lower than the temperature of the coil, and also increases the temperature of the mold in a portion far away from the resin injection port. Since this part is set to be gradually lowered from this part to the resin injection port, it is possible to prevent cavities and cracks from forming in the molded coil, and also to prevent the progress of resin curing from becoming unbalanced, improving its quality. It has excellent effects.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention together with an electrical configuration. Further, FIG. 2 is a diagram corresponding to FIG. 1 showing a conventional configuration. In the drawing, 11 is a mold, 13 is a coil, 16 is a resin injection port,
17 is a resin, 18 is an upper heater (heating means), 20 is a lower heater (heating means), 21 is a lower temperature sensor (first temperature detection means), 29 is a CPU (second temperature detection means),
control means).

Claims (2)

[Claims] 1. A method in which a coil, which is an object to be molded, 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 hardened by applying electricity to the coil to generate heat. The mold is heated so that the temperature is high in a part far from the resin injection port and gradually lowers from this part to the resin injection port, and the temperature of the mold is lower than the temperature of the coil. A resin curing method for a molded coil for electrical equipment, characterized in that energization to the coil or heating of the mold is controlled. 2. A coil as a molded object 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 hardened by applying electricity to the coil and generating heat. heating means for heating the mold so that the temperature of the mold is high in a portion far away from the resin injection port and gradually lowers from this portion to the resin injection port; a first temperature detection means for detecting temperature; and a second temperature detection means for detecting the temperature from a resistance value of the coil based on a voltage value between terminals of the coil and a current value of a current flowing through the coil.
energizing the coil or heating the mold so that the temperature of the mold becomes lower than the temperature of the coil based on detection signals output from the temperature detecting means and the first and second temperature detecting means. 1. A resin curing device for a molded coil for electrical equipment, comprising a control means for controlling.