JP6987733B2 - Insulation member and manufacturing method of insulation member - Google Patents

Description

The present invention relates to an insulating member and a method for manufacturing the insulating member.

In electrical equipment that has been used for a long period of time, it is known that a fine dendritic tube extends from a voltage application portion to a grounding portion inside the insulator and breaks down the insulation. This fine tube is called a tree, and the phenomenon in which the tree progresses is called treeing. This treeing almost determines the insulation life of electrical equipment. Therefore, by suppressing the treeing, the life of the electric device can be extended.

As a method of suppressing the treeing, a method of suppressing the growth by adding a filler to the insulating material to obstruct the growth path of the tree and increasing the branching of the tree (see Patent Document 1) and the orientation of the polymer insulating material. A method of controlling the traveling direction of the tree by control (see Patent Document 2) and the like are known.

The starting point (source) of the tree is known to be protrusions on the surface of the electrode, foreign matter in the solid, erosion of the solid due to void discharge, etc., all of which are parts where the electric field becomes high. In particular, when stress is present near the interface between the conductor and the insulating layer formed around it, peeling between the conductor and the insulating layer and minute cracks in the insulation near the interface are generated, and the peeling and minute cracks occur. It is known that a defect such as the above is the starting point and a tree is likely to occur (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-75069 Japanese Patent Application Laid-Open No. 2002-93258

As mentioned above, basic knowledge about the generation and progress of trees is being obtained, but a concrete form has not yet been established.

Therefore, an object of the present invention is to suppress the generation and development of trees in the insulating member.

The method for manufacturing an insulating member according to the present invention is a method for manufacturing an insulating member for covering an insulating object and electrically insulating it from the outside by injecting a heat-curable resin into a heating container and surrounding the insulating object. a filling step of filling, the heating step of heating the thermosetting resin filled in the filling step, have a, a cooling step of cooling the thermosetting resin after the heating step, the cooling step terminates Later, in the thermosetting resin, an insulating member having a larger compressive stress in the thickness direction is formed in the outer portion than in the inner portion in contact with the insulation target in the thickness direction, and in the heating step, the inner portion is formed. Is maintained at about room temperature, while the surface of the outer portion of the thermosetting resin in the thickness direction is heated so as to have a temperature distribution state such that the temperature is equal to or higher than the glass transition temperature. It is characterized in that, in a distributed state, a compressive stress is applied to the thermocurable resin in the thickness direction, and the thermocurable resin is cooled in a state where the compressive stress is applied .
Further, the method for manufacturing an insulating member according to the present invention is a method for manufacturing an insulating member for covering an insulating object and electrically insulating it from the outside, in which a heat-curable resin is injected into a heating container and the insulating object is manufactured. It has a filling step of filling around the surface, a heating step of heating the thermocurable resin filled in the filling step, and a cooling step of cooling the thermocurable resin after the heating step. After the end of the step, the heat-curable resin is formed with an insulating member having a larger compressive stress in the thickness direction in the outer portion than in the inner portion in contact with the insulation target in the thickness direction. The thermosetting resin is heated to be equal to or higher than the glass transition temperature, and in the cooling step, the cooling rate of the outer portion of the thermosetting resin is higher than the cooling rate of the inner portion. ..
Further, the method for manufacturing an insulating member according to the present invention is a method for manufacturing an insulating member for covering an insulating object and electrically insulating it from the outside, in which a thermosetting resin is injected into a heating container and the insulating object is manufactured. It has a filling step for filling around the surface, a heating step for heating the thermosetting resin filled in the filling step, and a cooling step for cooling the thermosetting resin after the heating step. After the step is completed, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction, and the thickness of the thermosetting resin is increased. In the direction, the first thermosetting resin is used for the outer portion, the second thermosetting resin is used for the inner portion, and the linear expansion rate after the thermosetting of the first thermosetting resin is It is characterized in that it is larger than the linear expansion rate after thermosetting of the second thermosetting resin.
Further, the method for manufacturing an insulating member according to the present invention is a method for manufacturing an insulating member for covering an insulating object and electrically insulating it from the outside, in which a thermosetting resin is injected into a heating container and the insulating object is manufactured. It has a filling step of filling around the surface, a heating step of heating the thermosetting resin filled in the filling step, and a cooling step of cooling the thermosetting resin after the heating step. After the step is completed, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction, and the thickness of the thermosetting resin is increased. In the direction, a third thermosetting resin is used for the outer portion, a fourth thermosetting resin is used for the inner portion, and the curing shrinkage rate of the third thermosetting resin is the fourth. It is characterized in that it is larger than the curing shrinkage rate of the thermosetting resin.

According to the present invention, it is possible to suppress the generation and development of trees in the insulating member.

It is sectional drawing which shows the structure of the insulating member which concerns on 1st Embodiment. It is a flow chart which shows the procedure of the manufacturing method of the insulating member which concerns on 1st Embodiment. It is a perspective view which shows the system in the manufacturing method of the insulating member which concerns on 1st Embodiment. It is a perspective view which shows the state after the injection of the thermosetting resin in the manufacturing method of the insulating member which concerns on 1st Embodiment. It is a perspective view which shows the state after formation of the insulating member in the manufacturing method of the insulating member which concerns on 1st Embodiment. It is a perspective view of the test apparatus for demonstrating the effect of the insulating member which concerns on 1st Embodiment. It is a vertical sectional view which shows the case of the 1st insulating member for demonstrating the effect of the insulating member which concerns on 1st Embodiment. It is a vertical sectional view which shows the case of the 2nd insulating member for demonstrating the effect of the insulating member which concerns on 1st Embodiment. It is a flow chart which shows the procedure of the manufacturing method of the insulating member which concerns on 2nd Embodiment. It is a perspective view which shows the system at the time of heating in the manufacturing method of the insulating member which concerns on 2nd Embodiment. It is a perspective view which shows the state after filling with the thermosetting resin in the manufacturing method of the insulating member which concerns on 2nd Embodiment. It is a perspective view which shows the system at the time of cooling of the outer surface side of the thermosetting resin in the manufacturing method of the insulating member which concerns on 2nd Embodiment. It is a flow chart which shows the procedure of the manufacturing method of the insulating member which concerns on 3rd Embodiment. It is a cross-sectional view which shows the state of the system at the stage which installed the partition tube in the manufacturing method of the insulating member which concerns on 3rd Embodiment. It is a cross-sectional view which shows the state at the stage of injecting a thermosetting resin in the manufacturing method of the insulating member which concerns on 3rd Embodiment. It is a cross-sectional view which shows the state of the stage which the heating and cooling are completed in the manufacturing method of the insulating member which concerns on 3rd Embodiment. It is a flow chart which shows the procedure of the manufacturing method of the insulating member which concerns on 4th Embodiment. It is a cross-sectional view which shows the state of the stage which the thermosetting resin is injected into the 1st heating container in the manufacturing method of the insulating member which concerns on 4th Embodiment. It is a cross-sectional view which shows the state of the stage which the heating and cooling by the 1st heating container are completed in the manufacturing method of the insulating member which concerns on 4th Embodiment. It is a cross-sectional view which shows the state of the stage which the thermosetting resin is injected into the 2nd heating container in the manufacturing method of the insulating member which concerns on 4th Embodiment. It is a cross-sectional view which shows the state of the stage which the heating and cooling by the 2nd heating container are completed in the manufacturing method of the insulating member which concerns on 4th Embodiment.

Hereinafter, the insulating member and the method for manufacturing the insulating member according to the present invention will be described with reference to the drawings. Here, common reference numerals are given to parts that are the same as or similar to each other, and duplicate description is omitted.

[First Embodiment]
FIG. 1 is a cross-sectional view showing the configuration of the insulating member according to the first embodiment.

The insulating member 10 is arranged outside the insulating object 1 such as a metal conductor. Here, the insulation target 1 is assumed to have various shapes, but in the following description, a case where the insulation target 1 is cylindrical and extends in the axial direction is shown assuming a metal conductor. Even when the insulation target 1 has another shape, the basic concept of the configuration of the insulating member and the method of manufacturing the insulating member shown below is the same.

Here, the insulating member 10 that covers the insulating object 1 and electrically insulates from the outside will be described as being arranged on the radial outer side of the insulating object 1 while being in close contact with the radial outer surface of the insulating object 1.

The insulating member 10 is obtained by thermosetting a thermosetting resin. As the thermosetting resin, an unsaturated polyester resin, an epoxy resin, a phenol resin, an unsaturated polyester resin and the like can be used.

The insulating member 10 has a first insulating layer 11, a second insulating layer 12, a third insulating layer 13, and a fourth insulating layer 14 which are sequentially arranged in layers from the outside to the inside in the radial direction, that is, in the thickness direction thereof. Here, the first insulating layer 11, the second insulating layer 12, the third insulating layer 13, and the fourth insulating layer 14 have different internal stress states, and at least the first insulating layer 11 is the outermost layer. In, compressive stress is working.

In this embodiment, it is shown as having four layers having different stress states, but the stress states do not change stepwise in the thickness direction. That is, what is continuously changing in the thickness direction is divided into four layers for convenience of explanation. In the present embodiment, the compressive stress is the largest on the outer surface of the first insulating layer 11. On the other hand, in the inner portion of the fourth insulating layer 14, that is, in the vicinity of the boundary between the fourth insulating layer 14 and the insulating object 1, the stress is small. Further, the compressive stress is sequentially reduced from the first insulating layer 11 to the fourth insulating layer 14.

FIG. 2 is a flow chart showing a procedure of a method for manufacturing an insulating member according to the first embodiment.

FIG. 3 is a perspective view showing a system in the method for manufacturing an insulating member according to the first embodiment. First, the insulation target 1 is installed inside the heating container 3 (step S11).

The heating container 3 is housed in the pressure-resistant container 5. The heating container 3 and the pressure-resistant container 5 are installed with their central axes oriented in the vertical direction. At this stage (step S01), the upper plate 5u is removed.

Here, the heating container 3 has a cylindrical shape at the side and has a bottom, corresponding to the shape of the columnar insulation target 1. The heating container 3 can heat the object stored inside the heating container 3 from the outside. In order to improve the efficiency of cooling the thermosetting resin after heating, which will be described later, for example, the heating container 3 can be divided so as to create a space between the thermosetting resin and the thermosetting resin after the curing. It may be configured.

The insulation target 1 is installed so that its axis is substantially centered in the radial direction of the heating container 3. An annular internal space 3a is formed on the radial outer side of the insulating object 1 inside the heating container 3.

The pressure-resistant container 5 is, for example, a closed container having a cylindrical side surface as shown in FIG. In FIG. 3, for the sake of explanation, the inside of the pressure-resistant container 5 is shown so as to be transparent, but the pressure-resistant container 5 does not have to be transparent. Further, the upper plate 5u of the pressure-resistant container 5 is formed to be removable, and when the upper plate 5u is removed, the upper portion of the pressure-resistant container 5 is open.

A pressure pipe 5a, a cooling gas injection pipe 5b, and an exhaust pipe 5c are connected to the upper plate 5u of the pressure-resistant container 5. The pressurizing pipe 5a is connected to a pressurizing source such as a compressor or a gas cylinder via a stop valve and a pressure reducing valve (not shown) that can be opened and closed. The cooling gas injection pipe 5b is connected to a cooling source such as a cooler via a stop valve (not shown) that can be opened and closed, and guides a cooling gas such as air into the pressure resistant container 5. The exhaust pipe 5c communicates with the outside air through a stop valve (not shown) that can be opened and closed, and discharges the gas in the pressure-resistant container 5 to the outside of the pressure-resistant container 5.

A cooling member 4 is attached to the insulation target 1. The cooling member 4 is thermally connected to a cooling source (not shown), and cools the insulation target 1 as needed. The cooling member 4 is mechanically connected to, for example, a cooling source, and heat removed from the insulation target 1 is removed by heat conduction. Alternatively, the cooling member 4 may be a heat exchanger or a heat pipe. The penetration portion of the pressure-resistant container 5 at the connection portion between the cooling member 4 and the outside is airtightly treated.

Next, the thermosetting resin 110 (FIG. 4) is injected into the inside of the heating container 3 and filled around the insulation target 1 (step S12). FIG. 4 is a perspective view showing a state after injection of the thermosetting resin. As shown in FIG. 4, the thermosetting resin 110 is injected into the internal space 3a shown in FIG. 3, and the thermosetting resin 110 is filled in the internal space 3a.

Next, the heating container 3 is heated to a high temperature to heat the outer periphery of the thermosetting resin 110 and cool the insulating object 1 (step S13). Specifically, the thermosetting resin 110 is heated from the outside in the radial direction by the heating container 3, and the insulation target 1 is cooled by the cooling member 4.

By heating from the outside in the radial direction, the surface temperature of the thermosetting resin 110 is set to be equal to or higher than the glass transition temperature of the thermosetting resin 110. Further, by cooling the insulation target 1, the temperature of the portion of the thermosetting resin 110 in contact with the insulation target 1 is set to about room temperature. As a result, the internal temperature of the thermosetting resin 110 has a temperature gradient from about room temperature to about the glass transition temperature from the portion in contact with the insulation target 1 to the surface of the thermosetting resin 110 in the thickness direction. It becomes a temperature distribution state. Here, about room temperature means about the temperature in the area where the work of forming the insulating member 10 is performed on the outside of the insulating object 1.

Next, the thermosetting resin is pressed with a temperature gradient in the thickness direction (step S14). Specifically, first, the upper plate 5u of the pressure-resistant container 5 is attached, and the pressure-resistant container 5 is sealed. Then, while maintaining the heating from the outside of the thermosetting resin 110 by the heating container 3 and the cooling state of the insulating object 1 by the cooling member 4, the inside of the pressure-resistant container 5 and the inside of the pressure-resistant container 5 are added via the pressure tube 5a. A high-pressure gas is introduced into the pressure-resistant container 5 by communicating with the pressure source.

Most of the thermosetting resins 110 shrink during thermosetting. Therefore, a clearance is generated between the heated thermosetting resin 110 and the heating container 3. By introducing a high-pressure gas into the pressure-resistant container 5, the thermosetting resin 110 is uniformly pressurized from the outside.

Further, when the thermosetting resin 110 hardly shrinks during heat curing, or conversely expands, the heating container 3 is divided into the heating container 3 before closing the upper plate 5u of the pressure resistant container 5. A gap is formed between the thermosetting resin 110 and the thermosetting resin 110 which is being cured by heating by then.

Next, the heating is finished, and the inside of the pressure-resistant container 5 is cooled to room temperature while maintaining the pressurized state (step S15). Specifically, in FIG. 3, only the pressurizing tube 5a may be made conductive with the inside of the pressure-resistant container 5 and left to be left for natural cooling. Alternatively, the cooling gas may be injected into the pressure resistant container 5 via the cooling gas injection pipe 5b. At this time, in order to maintain the internal pressure of the pressure-resistant container 5 within a predetermined range, the gas in the pressure-resistant container 5 is discharged to the outside from the exhaust pipe 5c in parallel with the injection of the cooling gas.

FIG. 5 is a perspective view showing a state after the formation of the insulating member. By the procedure of the method for manufacturing an insulating member as described above, the insulating member 10 is formed on the radial outer side of the insulating object 1. In the insulating member 10, as described with reference to FIG. 1, the compressive stress in the vicinity of contact with the insulating object 1 is small, while it is large on the surface opposite to the thickness direction, that is, on the outermost side in the thickness direction. It is in a state where compressive stress is applied.

FIG. 6 is a perspective view of a test device for explaining the effect of the insulating member according to the first embodiment. 7 is a vertical cross-sectional view showing the case of the first insulating member and FIG. 8 is a vertical sectional view showing the case of the second insulating member. Hereinafter, the contents of the conducted test and the actions and effects of the insulating member according to the first embodiment will be described with reference to FIGS. 6 to 8.

As shown in FIG. 6, in order to observe the progress of the tree, a device in which a needle electrode 2 and a cubic transparent epoxy resin insulator 201 are arranged around the needle electrode 2 is configured. The length L of one side of the insulator 201 is about 15 mm, and the distance D from the tip of the needle electrode 2 to the surface (lower surface of FIG. 6) of the facing insulator 201 is about 3 mm. 7 and 8 show the case of different stress states for the insulators 201a and 201b, respectively.

The distribution of compressive stress is observed by the photoelastic method. Here, the photoelastic method utilizes the fact that birefringence occurs when a load is applied to a transparent and non-anisotropic object or when stress remains in the object, and interference fringes reflecting the stress distribution are created. It is a method to generate and visualize the distribution.

In the first insulator 201a shown in FIG. 7, the compressed portion 202 corresponding to the interference fringes has one layer, and in the case of FIG. 8, the compressed portion 204 corresponding to the interference fringes has four layers. In either case, the compressive stress remains in a range beyond about 1.5 mm from the tip of the needle electrode 2.

However, the stress applied to the first insulator 201a shown in FIG. 7 is smaller than the stress applied to the second insulator 201b shown in FIG. In this state, in each system, the lower surfaces of the first insulator 201a and the second insulator 201b of the epoxy resin are grounded, and a high voltage of an AC waveform of 12 kHz and 50 Hz is applied to the needle electrode 2. did.

As a result, the tree continued to grow in the absence of compressive stress. Further, in the case of a region where compressive stress remains, the region penetrates into the region and progresses in the same manner up to about 2.0 to 2.5 mm, but beyond that, the growth of the tree is suppressed. It became.

In the case shown in FIG. 8, the dielectric breakdown time leading to the dielectric breakdown was longer than that in the case shown in FIG. 7, and the dielectric breakdown time was 410 hours. When the inside of some of the samples was observed while the voltage was applied, Tory 203 and Tory 205 were observed as shown in FIGS. 7 and 8, respectively. As described above, it was confirmed that the growth of the tree was suppressed in the region where the compressive stress was large.

In an electric device using the insulating member 10 according to the present embodiment, that is, an insulating object 1 such as a metal conductor and an electric device provided with an insulating member 10 covering the insulating object 1, the insulating object 1 and the insulating member 10 are used. The compressive stress at the interface is small, and a large compressive stress is applied to the outer surface of the insulating member 10 (the low voltage side of the insulating member 10).

In this state, a high potential is applied to the insulating object 1, and a ground potential is applied to the outer surface of the insulating member 10. At the interface with the insulation target 1, since the stress applied to the insulating member 10 is small, peeling or cracking, which is the starting point of the tree, is unlikely to occur. Further, if a tree is generated from this interface starting from an initial defect or the like, the tree propagates toward the outside in the thickness direction of the insulating member 10. As the tree grows and approaches the outer surface of the insulating member 10, the compressive stress increases and the growth of the tree is suppressed.

[Second Embodiment]
FIG. 9 is a flow chart showing a procedure of a method for manufacturing an insulating member according to a second embodiment. The second embodiment is a modification of the first embodiment.

first. The insulation target 1 is installed in the heating container 3 (step S21). FIG. 10 is a perspective view showing a heating system in the method for manufacturing an insulating member according to a second embodiment. As shown in FIG. 10, a heater 8 is connected to the insulation target 1. The heater 8 is, for example, a heater having a heat generating portion (not shown), or one in which heat is transferred from the heat generating portion by heat conduction, radiation, or the like.

Next, the thermosetting resin 110 is injected into the internal space 3a of the heating container 3 in the same manner as in the first embodiment (step S12). FIG. 11 is a perspective view showing a state after filling with a thermosetting resin.

After filling the thermosetting resin 110 in step S12, the heating container 3 is heated to a high temperature to heat the thermosetting resin 110 (step S23). In order to simultaneously heat the thermosetting resin 110 from the outside and the inside in the radial direction, the insulation target 1 is heated by the heater 8. In this way, the entire thermosetting resin 110 is raised above the glass transition temperature at almost the same time.

Next, the heating is completed, and the thermosetting resin 110 is cooled at a cooling rate on the outer surface side faster than the cooling rate on the inner surface side (step S24).

FIG. 12 is a perspective view showing a cooling system of the outer surface side of the thermosetting resin. The thermosetting resin 110 arranged in the insulation target 1 and its surroundings is taken out from the heating container 3, and a cooler 7 is arranged on the radial outer side of the thermosetting resin 110. The cooler 7 is connected to a cooling gas supply source (not shown), and blows a cooling gas such as cooled air to the radial outside of the thermosetting resin 110.

On the other hand, the heat insulating object 1 is supplied with heat from the heater 8 according to a predetermined cooling rate so that the cooling rate does not become too fast, and transfers the heat to the contact surface on the inner side in the radial direction of the thermosetting resin 110. do.

As described above, the outer surface side of the thermosetting resin 110 is cooled by the cooler 7 on the cooling side of, for example, about 30 ° C./Hr, and the inner surface side of the thermosetting resin 110 is suppressed by the heater 8. For example, it is cooled at a cooling rate of about 10 ° C./Hr.

Note that FIG. 12 shows, as an example, a case where the cooling gas is sprayed on the outer surface side of the thermosetting resin 110 by the cooler 7 to secure the cooling rate, but the present invention is not limited to this. For example, the outside of the thermosetting resin 110 may be filled with a liquid to control the temperature of the liquid.

As described above, the thermosetting resin 110 is thermally cured by slowly cooling the temperature of the peripheral portion of the insulating object 1, that is, the inner portion of the thermosetting resin 110 so as not to be different from the temperature of the insulating object 1. It is possible to reduce the stress in the peripheral portion of the insulating object 1 of the sex resin 110. Further, by cooling the outside of the thermosetting resin 110 at a high speed, a large compressive stress can be applied to the outer portion of the thermosetting resin 110.

[Third Embodiment]
FIG. 13 is a flow chart showing a procedure of a method for manufacturing an insulating member according to a third embodiment. This embodiment is a modification of the first embodiment.

First, the insulation target 1 is installed in the heating container 3 (step S31).

Next, the partition cylinder is installed in the annular space sandwiched between the heating container 3 and the insulation target 1 (step S32).

FIG. 14 is a cross-sectional view showing a state of a system at a stage in which a partition tube is installed in the method for manufacturing an insulating member according to a third embodiment. The annular space sandwiched between the heating container 3 and the insulating object 1 is radially divided into an outer space 3b and an inner space 3c by the partition cylinder 6. Here, as the compartment cylinder 6, a thermosetting resin that has been heat-cured is used. Further, as the thermosetting resin, either the resin 31 for a high linear expansion coefficient insulating material or the resin 32 for a low linear expansion coefficient insulating material, which will be described later, is used.

Next, the outer space 3b and the inner space 3c shown in FIG. 14 are each filled with a thermosetting resin (step S33).

FIG. 15 is a cross-sectional view showing a state in which a thermosetting resin is injected in the method for manufacturing an insulating member according to a third embodiment. The outer space 3b is filled with the resin 31 for a high linear expansion coefficient insulating material, and the inner space 3c is filled with a resin 32 for a low linear expansion coefficient insulating material.

Here, as the resin 32 for a low linear expansion coefficient insulating material, a resin whose linear expansion coefficient after thermal curing is substantially the same as the linear expansion coefficient of the insulation target 1 is selected. Here, substantially the same degree means that when the low linear expansion coefficient insulating material resin 32 has a larger linear expansion coefficient than the insulating target 1, the low linear expansion coefficient insulating material resin 32 and the insulating target 1 are used. If the difference in the linear expansion coefficient is such that peeling does not occur between the two, and the linear expansion coefficient of the resin 32 for the low linear expansion coefficient insulating material is smaller than that of the insulation target 1, the resin for the low linear expansion coefficient insulating material. It is assumed that the difference in linear expansion coefficient is such that stress that causes cracks in 32 is not generated. Further, as the resin 31 for the high linear expansion coefficient insulating material, a resin having a larger linear expansion coefficient after thermal curing than the resin 32 for the low linear expansion coefficient insulating material is selected.

For example, when the linear expansion coefficient of the insulation target 1 is aluminum, the low linear expansion coefficient insulating member 32a (FIG. 16) formed by thermosetting the resin 32 for the low linear expansion coefficient insulating material is, for example, 24, which is similar to that of aluminum. Select a resin that has a linear expansion coefficient of about × ^{10-6 / ° C.} Further, the high linear expansion coefficient insulating member 31a (FIG. 16) formed by thermosetting the resin 31 for a high linear expansion coefficient insulating material is an epoxy having, for example, about 45 × 10 ^{-6 to} 65 × 10 ^-6 / ° C. Select the resin.

Next, the heating container 3 is heated to a high temperature to heat the insulation target 1 (step S34). That is, the temperature of the resin 31 for the high linear expansion coefficient insulating material and the resin 32 for the low linear expansion coefficient insulating material is raised to a temperature equal to or higher than the glass transition temperature.

Next, heating is completed, and the heating container 3 is removed (step S35). FIG. 16 is a cross-sectional view showing a state in which heating and cooling are completed in the method for manufacturing an insulating member according to a third embodiment. The resin 31 for the high linear expansion coefficient insulating material filled in the outer space 3b becomes the high linear expansion coefficient insulating member 31a, and the resin 32 for the low linear expansion coefficient insulating material filled in the inner space 3c becomes the low linear expansion coefficient insulating member 32a. ing. Instead of removing the heating container 3, the low linear expansion coefficient insulating member 32a and the high linear expansion coefficient insulating member 31a formed around the insulating target 1 and the insulating target 1 may be taken out from the heating container 3.

Although FIGS. 14 to 16 show an example in which two types of layers are formed in the radial direction, three or more types of layers may be formed in the radial direction. In this case, a required number of compartment cylinders are installed according to the number of layers. Further, a thermosetting resin is selected so that the innermost layer has a linear expansion rate similar to the linear expansion rate of the insulation target 1 after thermal curing, and the outermost layer is, for example, high linear expansion rate insulation after thermal curing. A thermosetting resin similar to the material resin 31 is selected. Further, in the region sandwiched between them, a thermosetting resin is selected so that the linear expansion coefficient monotonically decreases from the outside to the inside in the thickness direction after thermosetting.

As a method of gradienting the coefficient of linear expansion, only a mixed solution of an epoxy resin and a curing agent is used for the outermost layer. The coefficient of linear expansion of the epoxy resin ^{is about 45 × 10 −6 to} 65 × 10 ⁻⁶ / ° C. as described above. In the inner layer thereof, a mixed solution of an epoxy resin and a curing agent and a mixed solution of inorganic particles such as silica or alumina having a small coefficient of linear expansion are prepared and used. In this case, the coefficient of linear expansion is, for example, ^{about 20 × 10 −6} / ° C. The concentration of these inorganic particles is increased toward the inside. As the innermost layer, a layer adjusted so that the coefficient of linear expansion after thermal curing is about the same as the coefficient of linear expansion of the insulation target 1 is used. As the inorganic particles to be blended, those having a particle size in the range of nanometer to micrometer may be blended alone or a plurality of types may be blended at the same time.

As described above, in the method for manufacturing an insulating member according to the present embodiment, the coefficient of linear expansion of each layer can be set to a desired value.

In this embodiment, the case of using a compartment cylinder is shown as an example, but instead, the inner layer is heat-cured, and then a thermosetting resin is placed on the outer side and then heat-cured. It is also possible to form a multi-layered insulating member by sequentially carrying out the procedure.

By forming as described above, the insulating member produced by curing the thermosetting resin has a large coefficient of linear expansion in the outer portion having a large coefficient of linear expansion. Therefore, when the temperature rises from room temperature, the outer side in the thickness direction becomes hotter. The expansion increases. Therefore, an insulating member having a larger compressive stress can be obtained toward the outer side in the thickness direction.

[Fourth Embodiment]
FIG. 17 is a flow chart showing a procedure of a method for manufacturing an insulating member according to a fourth embodiment. This embodiment is a modification of the third embodiment. Also in this embodiment, two types of thermosetting resins having different characteristics are used, but the thermosetting resin at the time of injection is different from the third embodiment. The manufacturing method is also different from that of the third embodiment. Specifically, two types of heating containers are used. Other than these, it is basically the same as the third embodiment.

FIG. 18 is a cross-sectional view showing a state in which a thermosetting resin is injected into the first heating container.

First, the insulation target 1 is installed in the first heating container 43a (step S41).

Next, the thermosetting resin is injected into the annular space sandwiched between the first heating container 43a and the insulating object 1 (step S42). The thermosetting resin to be injected at this time is a low curing shrinkage resin 42 having a small shrinkage rate at the time of heat curing, that is, a small curing shrinkage rate.

Next, the low-curing shrinkage resin 42 is heated by the first heating container 43a, and then the low-curing shrinkage resin 42 is cooled (step S43). FIG. 19 is a cross-sectional view showing a state in which heating and cooling by the first heating container are completed. The low curing shrinkage resin 42 is the second insulating member 42a.

Next, the insulation target 1 in which the second insulating member 42a is arranged around the second insulating member 42a is installed in the second heating container 43b (step S44). That is, the insulation target 1 around which the second insulating member 42a is arranged is transferred from the inside of the first heating container 43a to the inside of the second heating container 43b having a diameter larger than that of the first heating container 43a.

Next, the thermosetting resin is injected into the annular space sandwiched between the second heating container 43b and the second insulating member 42a (step S45). FIG. 20 is a cross-sectional view showing a state at which the thermosetting resin is injected into the second heating container. The thermosetting resin to be injected at this time is a high-curing shrinkage resin 41 having a higher curing shrinkage rate than the low-curing shrinkage resin 42.

Next, the high-curing shrinkage resin 41 is heated by the second heating container 43b, and then the high-curing shrinkage resin 41 is cooled (step S46). FIG. 21 is a cross-sectional view showing a state in which heating and cooling by the second heating container are completed. The high curing shrinkage resin 41 is the first insulating member 41a.

In addition, in this embodiment, the point that a plurality of layers may be formed is the same as the content described in the third embodiment.

By forming as described above, since the thermosetting resin has a large curing shrinkage rate of the outer portion, the thermosetting resin shrinks toward the outside in the thickness direction at the stage of being heated and thermally cured. As a result, the cured thermosetting resin is subjected to tensile stress in the circumferential direction but compressive stress in the radial direction.

When a voltage is applied between the insulation target 1 and the outer surface of the first insulating member 41a, the potential gradient is formed in the radial direction, that is, in the thickness direction of the first insulating member 41a. Therefore, the growth direction of the tree is the radial direction (thickness direction). In the present embodiment, since compressive stress is formed in the radial direction, it has an effect of suppressing the growth of the tree.

Further, by arranging the first insulating member 41a obtained by arranging the high curing shrinkage resin 41 having a large curing shrinkage rate around the second insulating member 42a in which the low curing shrinkage resin 42 is heat-cured, the first insulating member 41a is heat-cured. , A large radial compressive stress is generated in the first insulating member 41a. Further, in the inner second insulating member 42a, a compressive stress is generated by the rattling force of the first insulating member 41a, but this range remains in the vicinity of the surface of the second insulating member 42a. The radial inner region in the second insulating member 42a is almost the same as the state shown in FIG. 19 in step S43, and the stress is low.

As described above, also in the fourth embodiment, the compressive stress is formed in the gradient direction of the potential, and the generation and the growth of the tree in the insulating member can be suppressed.

[Other embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. For example, in the embodiment, the case where the insulation target 1 is a cylinder is shown as an example, but the insulation target 1 is not limited to the cylinder. The insulation target 1 may be, for example, one having a polygonal or curved cross section and a columnar shape, one having a shape such as a sphere, an ellipsoid, or a rectangular parallelepiped, one having a plate shape or a thin curved surface, or a combination thereof. .. In these cases, the shape of the heating container 3 and the partition cylinder 6 in the third and fourth embodiments may be set to an appropriate shape according to the shape of the insulation target 1.

Moreover, you may combine the features of each embodiment. Further, the embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

1 ... Insulation target, 2 ... Needle electrode, 3 ... Heating container, 3a ... Internal space, 3b ... Outer space, 3c ... Inner space, 4 ... Cooling member, 5 ... Pressure-resistant container, 5a ... Pressurized tube, 5b ... For cooling Gas injection pipe, 5c ... Exhaust pipe plate, 5u ... Top plate, 6 ... Partition cylinder, 7 ... Cooler, 8 ... Heater, 10 ... Insulating member, 11 ... First insulating layer, 12 ... Second insulating layer, 13 ... 3rd insulating layer, 14 ... 4th insulating layer, 31 ... resin for high wire expansion rate insulating material, 31a ... high wire expansion rate insulating member, 32 ... resin for low wire expansion rate insulating material, 32a ... low wire expansion rate Insulating member, 41 ... High curing shrinkage resin, 41a ... First insulating member, 42 ... Low curing shrinkage resin, 42a ... Second insulating member, 43a ... First heating container, 43b ... Second heating container, 110 ... Thermo-curable resin, 201 ... Insulator, 201a ... First insulator, 201b ... Second insulator, 202 ... Compressed part, 203 ... Tree, 204 ... Compressed part, 205 ... Tree

Claims (5)

It is a method of manufacturing an insulating member to cover an insulating object and electrically insulate it from the outside.
A filling step of injecting a thermosetting resin into a heating container and filling the periphery of the insulation target,
A heating step for heating the thermosetting resin filled in the filling step, and a heating step.
After the heating step, a cooling step for cooling the thermosetting resin, and
Have,
After the completion of the cooling step, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction.
In the heating step, the inner portion is maintained at about room temperature, while the surface of the outer portion in the thickness direction of the thermosetting resin is heated so as to have a temperature distribution state such that the temperature is equal to or higher than the glass transition temperature. ,
In the cooling step, a compressive stress is applied to the thermosetting resin in the thickness direction in the temperature distribution state, and the thermosetting resin is cooled in the state where the compressive stress is applied.
A method for manufacturing an insulating member. It is a method of manufacturing an insulating member to cover an insulating object and electrically insulate it from the outside.
A filling step of injecting a thermosetting resin into a heating container and filling the periphery of the insulation target,
A heating step for heating the thermosetting resin filled in the filling step, and a heating step.
After the heating step, a cooling step for cooling the thermosetting resin, and
Have,
After the completion of the cooling step, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction.
In the heating step, the thermosetting resin is heated so as to be equal to or higher than the glass transition temperature.
Wherein in the cooling step, the cooling rate of the outer portion of the thermosetting resin, the manufacturing method of the insulation member you being greater than the cooling rate of the inner portion. It is a method of manufacturing an insulating member to cover an insulating object and electrically insulate it from the outside.
A filling step of injecting a thermosetting resin into a heating container and filling the periphery of the insulation target,
A heating step for heating the thermosetting resin filled in the filling step, and a heating step.
After the heating step, a cooling step for cooling the thermosetting resin, and
Have,
After the completion of the cooling step, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction.
In the thickness direction of the thermosetting resin, the first thermosetting resin is used for the outer portion, the second thermosetting resin is used for the inner portion, and the heat of the first thermosetting resin is used. linear expansion coefficient after curing method of insulation member characterized in that greater than said second coefficient of linear expansion after thermal curing of the thermosetting resin. The method for manufacturing an insulating member according to claim 3 , wherein the coefficient of linear expansion of the second thermosetting resin after thermosetting is about the same as the coefficient of linear expansion of the object to be insulated. It is a method of manufacturing an insulating member to cover an insulating object and electrically insulate it from the outside.
A filling step of injecting a thermosetting resin into a heating container and filling the periphery of the insulation target,
A heating step for heating the thermosetting resin filled in the filling step, and a heating step.
After the heating step, a cooling step for cooling the thermosetting resin, and
Have,
After the completion of the cooling step, the thermosetting resin is formed with an insulating member having a larger compressive stress in the thickness direction on the outer portion than on the inner portion in contact with the insulation target in the thickness direction .
In the thickness direction of the thermosetting resin, a third thermosetting resin is used for the outer portion, a fourth thermosetting resin is used for the inner portion, and the third thermosetting resin is cured. A method for manufacturing an insulating member , wherein the shrinkage rate is larger than the cure shrinkage rate of the fourth thermosetting resin.

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