JP2007021874A - Method and device for thermally insulating cast epoxy resin article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for thermally insulating a cast epoxy resin article which can reduce residual stress generated in the interface between a resin and an embedded metal product, improve the properties of the article, and stabilize the quality of the article. <P>SOLUTION: An iron plate 1 is mounted on a frame 2 equipped with a roller placed on a mounting surface and casters fitted to the tips of four legs, and an insulating component 3 of an epoxy resin which is primarily cured and taken out from a mold is mounted on the iron plate 1. A heating wire 4 is embedded in the iron plate 1 and a temperature sensor 5 measuring the temperature of the iron plate 1 is set on the surface of the iron plate 1. A monitor control panel 8 is connected through connectors 6 and 7. The temperature of the iron plate 1 measured by the temperature sensor 5 can be observed by the monitor control panel 8, and the temperature of the iron plate 1 can be set through the heating wire 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention reduces the stress generated at the interface between the resin and the embedded hardware that occurs during the secondary curing after the primary curing, for products manufactured by the mass production method such as the pressure gelation method of epoxy resin cast products. The present invention relates to a method and a heat-retaining device for epoxy resin cast products.

  Conventionally, epoxy resin cast products have been used in various fields because of their excellent electrical insulation and mechanical properties as solid insulators. In particular, it is widely used as an insulator for high-voltage power transformers and requires long-term reliability.

Generally, the casting is cured into a primary curing performed in a mold for molding and a secondary curing for imparting final physical properties and determining product dimensions. In recent years, the pressure gelation method has been applied to mass-produce high-quality and reliable castings in a short time, and this pressure gelation method uses a highly reactive epoxy resin. The resin is poured into the mold in a state where the temperature of the mold is several steps higher than the resin temperature, and the pressure is continuously supplied to compensate for the shrinkage of the resin during curing until the curing is completed.
Japanese Patent Laid-Open No. 10-130464

  By the way, in the pressure gelation method, the product is taken out in a state that has reached a certain hardness that allows the product to be taken out from the mold. At this time, the shrinkage force at the time of curing is the boundary surface between the resin and the embedded hardware. Occurs as residual stress. In particular, since curing is performed in a short time using a highly reactive epoxy resin, curing shrinkage and heat generation are large, and the influence of residual stress on the interface between the resin and the embedded metal is large.

  In addition, due to the temperature drop after mold release, stress generated by heat shrinkage is further applied to the interface between the resin and the embedded metal, but in the case of a product shape in which the thickness of the resin is set to be large, the mold release Due to the difference in temperature between the inside and outside of the later product and the difference in thermal conductivity between the resin and the conductor, the state of the interface between the resin and the metal tends to become more unstable. As described above, when the primary curing is performed at a high temperature, the influence of the heat shrinkage is large, and it has been a problem to produce a stable product.

  On the other hand, it is possible to reduce the effect of the residual stress by reducing the effect of temperature drop after primary curing, but in view of the possession status of secondary curing furnaces and the current state of process management, It was difficult to manage to prevent temperature drop under suitable conditions. In particular, in the case of a production method with high productivity in a short time, such as a pressure gelation method, the problem has become more prominent.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the residual stress generated at the interface between the resin and the embedded metal, and to improve the characteristics and quality of the epoxy resin cast product. An object of the present invention is to provide a heat-retaining method and a heat-retaining device for an epoxy resin cast product that can be made to be heated.

  In order to achieve the above object, the present invention includes a primary curing step of injecting an epoxy resin into a mold and heat-curing, and a secondary curing step of determining a product size of the primary-cured epoxy resin cast product. In the meantime, the epoxy resin cast product is placed on a heating plate provided with a heating means inside, and is provided with a heat retention step of heating to a constant temperature for a predetermined time.

  According to the present invention as described above, conventionally, the epoxy resin cast product after the primary curing is simply lowered to room temperature without providing a heat retaining step, and then a certain number is collectively collected. In the present invention, after the primary curing, the epoxy resin cast product after the primary curing is kept at a constant temperature for a certain period of time on a heating plate provided with a heating means such as a heater wire. Therefore, after primary curing, reduce the residual stress generated at the interface between the epoxy resin and the embedded metal and the thermal shrinkage due to the temperature drop of the product, improve the mechanical properties and insulation performance, and stabilize the quality. Can do.

In addition to the above-mentioned invention, the present invention is characterized in that the temperature at which the epoxy resin cast product is heated is in the range from the glass transition temperature after the primary curing to the secondary curing temperature.
In the above-described embodiment, when the epoxy resin cast product is lower than the glass transition temperature given by the primary curing between the primary curing and the secondary curing, the residual stress between the epoxy resin and the embedded metal On the other hand, if the temperature of the epoxy resin casting exceeds the secondary curing temperature, it will be affected by extreme reaction progress and oxidative degradation. Since the glass transition temperature imparted by the primary curing is the lower limit value and the upper limit is within the range of the secondary curing temperature, which is the next step, there is no such disadvantage as described above.

  The present invention also provides an apparatus for realizing the above-described method. Primary curing is performed by injecting an epoxy resin into a mold and heat-curing, and secondary determining the product dimensions of the first-cured epoxy resin cast product. An epoxy resin cast product thermal insulation device that keeps the epoxy resin cast product warm during curing, and has a heating means inside to place a primary cured epoxy resin cast product A heating plate on which the heating plate is mounted, a temperature sensor for measuring the temperature of the heating plate is provided on the heating plate, and the heater wire and the temperature sensor include A control unit is connected to the temperature of the heating plate.

  In the above-described aspect, after the primary curing, on the heating plate provided with heating means such as a heater wire inside, the epoxy resin cast product after the primary curing is kept at a constant temperature for a certain period of time. After curing, the residual stress generated at the interface between the epoxy resin and the embedded metal and the thermal shrinkage due to the temperature drop of the product can be reduced, the mechanical properties and insulation performance can be improved, and the quality can be stabilized. By controlling the ambient temperature and the temperature on the heating plate with the temperature sensor by means of the temperature sensor, it is possible to perform management to prevent a temperature drop under conditions suitable for individual products.

In another aspect of the heat retaining device, the gantry is configured to be movable, and the heating plate is slidably mounted.
In the above-described aspect, the gantry is configured to be movable by a moving member such as a caster, and the heating plate on the gantry is configured to be slidable by a sliding member such as a roller contactor. The heating plate can be carried into the secondary curing furnace. Therefore, even if a heat retention step is added after the primary curing, the same treatment can be performed on a large number of products at the same time, and it is possible to proceed to the next step as it is, thus reducing productivity without increasing the number of extra steps. There is nothing.

  ADVANTAGE OF THE INVENTION According to the present invention, a method and a heat retaining device for an epoxy resin cast product that can reduce residual stress generated at the interface between the resin and the embedded metal and can improve the quality and stabilize the quality of the epoxy resin cast product. Can be provided.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings. In addition, the premise common to the content already demonstrated by the background art and the subject is abbreviate | omitted suitably.

[1. Constitution]
FIG. 1 is a view showing a heat-insulating device for an epoxy resin cast product according to the present embodiment. As a heating plate on a gantry 2 provided with a roller concentrator on the mounting surface and a caster at the tip of four legs. The iron plate 1 is placed, and on this iron plate 1 is mounted an insulating component 3 which is an epoxy resin cast product which has been subjected to primary curing and taken out from the mold. The insulating component 3 is a disk-shaped insulating spacer used for a gas-insulated switchgear or the like, a cylindrical insulating cylinder having a resin thickness exceeding 100 mm, and the like. Further, the iron plate 1 is movable on the gantry 2 by a roller contact provided on the mounting surface of the gantry 2.

  Here, in general, in the case of a product having a large insulating part 3, the part 3 may be corrected to a predetermined size with a jig or the like. In this case, if there is a temperature difference between the jig and the insulating part 3, Due to a temperature drop caused by a jig or the like, an influence due to thermal contraction of the insulating component 3 occurs. Therefore, not only the insulating component 3 but also a jig for molding components can be placed on the iron plate 1.

  A plurality of heater wires 4 are embedded in the iron plate 1, and a temperature sensor 5 for measuring the temperature of the iron plate 1 is provided on the surface of the iron plate 1. Further, connectors 6 and 7 for supplying electric power to the heater wire 4 and the temperature sensor 5 are attached to one end of the side surface of the iron plate 1 in a detachable configuration.

  A monitor control panel 8 is connected via the connectors 6 and 7, and the monitor control panel 8 can observe the temperature of the iron plate 1 measured by the temperature sensor 5, and the temperature of the iron plate 1 can be measured via the heater wire 4. It is configured so that it can be set. The monitor control panel 8 is configured so that the temperature can be easily raised at a temperature of 200 ° C. or lower.

  As shown in the figure, a heat insulating plate 9 is provided on each side of the iron plate 1, and the iron plate 1 is stably maintained at a constant temperature due to the presence of the heat insulating plate 9.

[2. Effect]
In the present embodiment having the above-described configuration, the temperature of the iron plate 1 is set via the heater wire 4 while the gas insulating component 3 that has undergone primary curing is placed on the iron plate 1 and the temperature is monitored by the monitor control panel 8. Is kept at a predetermined temperature for a certain period of time to keep the insulating component 3 warm.

  Here, if the set temperature of the heater wire 4 is not higher than the glass transition temperature given by the primary curing, the stress will not be released, the reaction will proceed if the secondary curing temperature is exceeded, and if it exceeds 150 ° C It is necessary to set in consideration that the thermal deterioration of the epoxy resin starts. Based on this, for example, if the glass transition temperature after primary curing is about 100 ° C., it is desirable to keep the temperature at about 130 ° C. Further, in the case of a general casting resin, if the time is less than 5 hours, there is little influence on the progress of the reaction.

  After the insulating component 3 is kept warm on the iron plate 1 as a heating plate for a predetermined time as described above, the gantry 2 is moved to the vicinity of the secondary curing furnace 10 by rolling the caster, and the secondary curing furnace 10 Inside, the iron plate 1 is slid by a roller control on the gantry 2 and carried in. At this time, the connectors 6 and 7 connected to the heater wire 4 and the temperature sensor 5 are removed from the iron plate 1.

  The present embodiment as described above has the following effects. That is, in the past, for the insulation parts after the primary curing, the temperature was simply lowered to room temperature without providing a heat retaining step, and then the secondary curing was performed for a certain number of pieces. In the embodiment, after the primary curing, the insulating part 3 after the primary curing is kept at a constant temperature for a certain period of time on the iron plate 1 provided with the heater wire 4 therein. Therefore, after the primary curing, the boundary between the epoxy resin and the embedded hardware Residual stress generated on the surface and thermal shrinkage due to a decrease in product temperature can be reduced, and mechanical characteristics and insulation performance can be improved and quality can be stabilized.

  In addition, according to the heat retaining device of the present embodiment, the heater wire 4 is embedded in the iron plate 1 so that the heater wire 4 can be heated at a constant temperature, and the insulating component 3 and the jig used therefor are placed directly on the iron plate 1. It is possible to keep warm. In addition, the temperature on the iron plate 1 can be monitored by the monitor control panel 8 via the temperature sensor 5 provided on the iron plate 1.

  In the gantry 2, the connectors 6 and 7 of the heater wire 4 and the sensor 5 are configured to be detachable from the iron plate 1, and further provided with casters and roller contacts, so that the gantry 2 itself moves and the gantry 2 on the iron plate 1 is mounted on the gantry 2. In addition to being easy to move, the entire iron plate 1 can be carried into the secondary curing furnace 10 after the heat retention step. Therefore, even if a heat retention step is added after the primary curing, the same treatment can be performed on a large number of products at the same time, and it is possible to proceed to the next step as it is, thus reducing productivity without increasing the number of extra steps. There is nothing.

  When the insulating component 3 is made below the glass transition temperature given by the primary curing between the primary curing and the secondary curing, it is difficult to release the residual stress between the epoxy resin and the embedded metal, On the other hand, when the temperature of the insulating component 3 exceeds the secondary curing temperature, it is affected by the progress of an extreme reaction and oxidative degradation, but in this embodiment, the temperature of the insulating component 3 is maintained at the glass transition temperature provided by the primary curing. Is the lower limit, and the upper limit is within the range of the secondary curing temperature, which is the next step.

[3. Example]
Next, the example by the above heat retention processes is shown with a comparative example. As shown in Table 1, the product strength by the pressure load of the disk-shaped insulation spacer (Example) which passed through the heat retention process shown in this embodiment and the insulation spacer (Comparative Example) which did not pass through the heat retention process was measured. As a result, it is 3.2 MPa in the example, whereas it is 2.8 MPa in the comparative example, and it can be seen that the mechanical strength is improved by 20% or more by performing the heat retaining step of the present embodiment. Thus, the strength of the insulating component is improved by passing through a heat retaining step after the primary curing.

In Table 2, four cylindrical insulating parts having a resin wall thickness exceeding 100 mm are prepared, and after the glass transition temperature of primary curing is set to about 100 ° C., the heat retaining device of this embodiment is used. The results of a heat shock test in which the insulating components 3 were alternately exposed to a high temperature of 100 ° C. or higher and a low temperature of 0 ° C. or lower under four different heat retention conditions (temperature load conditions) and subjected to thermal shock were summarized. Note that “destruction” in Table 2 refers to the case where a crack occurs at the interface between the resin and the resin and the embedded metal. “Temperature load condition” in the column represents that the high temperature and low temperature were alternately repeated seven times in the order of (1) to (7), and “Tg” in the table represents the glass transition temperature after primary curing. Indicates.

  According to this, the lower the heat insulation condition is lower than the glass transition temperature after primary curing, the faster the insulation components break down, and it is more resistant to thermal shock by adding a heat insulation process at a temperature higher than the glass transition temperature after primary curing. You can see that

  Thus, it can be seen that by adding a heat retention step at a temperature higher than the glass transition temperature after primary curing, the effect of residual stress is reduced, and the product strength is improved against the suppression of internal defects and thermal shock.

  As described above, it can be seen that the mechanical strength of the disc-shaped insulating spacer and the like is improved by 20% or more by adding the heat retaining step after the primary curing. In addition, for cylindrical insulating parts with a resin wall thickness exceeding 100 mm instead of a disk shape, if the primary curing is performed in a short time at a high temperature, heat shrinkage causes “(1) Thermal insulation” in Table 2 “30 ° C. × 4 hours”. As shown in “After”, a defect of 50% or more occurred inside, but in the present embodiment, the yield was reduced to 5% or less. Furthermore, when heat shock was forcibly applied, it was confirmed that the strength was improved by releasing the residual stress without breaking even in the temperature range where it was broken conventionally.

The image figure which shows the structure of the heat retention apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Iron plate 2 ... Base 3 ... Gas insulation component 4 ... Heater wire 5 ... Temperature sensor 6, 7 ... Connector 8 ... Monitor control panel 9 ... Heat insulation board 10 ... Secondary curing furnace

Claims (4)

  Between the primary curing step of injecting an epoxy resin into the mold and heat curing, and the secondary curing step of determining the product dimensions of the primary cured epoxy resin cast product, the epoxy resin cast product, An epoxy resin cast product heat-retaining method comprising a heat-retaining step which is placed on a heating plate having a heating means inside and heated to a constant temperature for a predetermined time.   The method for keeping a temperature of an epoxy resin cast product according to claim 1, wherein the temperature at which the epoxy resin cast product is heated is within a range from a glass transition temperature after primary curing to a secondary curing temperature. An epoxy that keeps the epoxy resin cast product warm between primary curing in which epoxy resin is injected into the mold and heat-cured and secondary curing that determines the product dimensions of the primary cured epoxy resin cast product. A heat-insulating device for resin cast products,
A heating plate provided with a heating means inside, and formed with a mounting table on which a first-cured epoxy resin cast product is mounted,
A gantry on which the heating plate is placed;
The heating plate is provided with a temperature sensor for measuring the temperature of the heating plate,
The warming device for epoxy resin cast products, wherein a controller for controlling the temperature of the warming plate is connected to the warming means and the temperature sensor.   The epoxy resin cast product heat retaining device according to claim 3, wherein the gantry is configured to be movable, and the heating plate is slidably mounted thereon.

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