Mold for molding insulating spacer and molding method

Abstract

To simplify the process and ease restrictions in molding.SOLUTION: A mold (31) for molding an insulating spacer (10) comprises a spacer cone section (12) that is provided around a center conductor (11) while supporting the center conductor (11) and formed into a cone shape. The mold for molding has a lower mold (32) and an upper mold (34) that form a cavity (33) shaped according to the insulating spacer. The cavity has a plurality of spacer cone section forming parts (35) corresponding to the plurality of spacer cone sections, and a flow channel (39) formed in the form of a slit that is connected to the two spacer cone section forming parts and through which the resin material injected into the cavity flows.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] In particular, the present invention relates to a molding die and a molding method for insulating spacers used in gas-insulated switchgear. [Background technology]

[0002] Patent Document 1 discloses an insulating spacer used to support a conductor in a metal container of a gas-insulated device. The insulating spacer is configured to change the dielectric constant of the material between the high-voltage side and the ground side, so that the high-voltage side has a higher dielectric constant than the ground side. With this configuration, it is intended to provide a more compact insulating spacer while still satisfying the required insulation performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-126527 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the process requires two steps: obtaining a string-like extrusion product from a material in which a thermosetting resin and a filler are kneaded, and feeding the string-like extrusion product into the lower die of an insulating spacer molding die and supplying it in a spiral manner. In addition, in Patent Document 1, the material for obtaining the string-like extrusion product is continuously extruded by linearly increasing and decreasing the supply of the filler, and there is a molding restriction in that the extrusion cannot be interrupted.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a method for molding an insulating spacer, which can simplify the process and ease the restrictions imposed on molding. [Means for solving the problem]

[0006] One embodiment of the present invention provides a molding die for an insulating spacer, which supports a central conductor and has a plurality of spacer cone portions formed into a cone shape around the central conductor, and is characterized in that the molding die for an insulating spacer includes a lower mold and an upper mold for forming a cavity having a shape corresponding to the insulating spacer, and the cavity includes a plurality of spacer cone portion forming portions corresponding to the plurality of spacer cone portions, and a flow path formed in a slit shape communicating with at least two of the spacer cone portion forming portions, through which a resin material injected into the cavity flows.

[0007] A molding method for an insulating spacer according to one embodiment of the present invention is a molding method for an insulating spacer having a plurality of spacer cone portions formed in a cone shape around a central conductor while supporting the central conductor, using the molding die and a nozzle that injects a resin material into the cavity of the molding die, and is characterized in that the method includes a die arrangement step of arranging the molding die with a top forming portion of the cone shape in the cavity facing down, a lamination step of injecting the resin material into the cavity via the nozzle a plurality of times, causing the resin material to flow into all of the plurality of spacer cone portion forming portions through the flow path, and laminating a plurality of resin layers in the vertical direction, a curing step of hardening the resin layers laminated in the lamination step, and releasing the insulating spacer from the molding die, and a removal step of removing a residual portion of the insulating spacer formed of the resin material hardened in the flow path from the spacer cone portions. Effect of the Invention

[0008] According to the present invention, the resin material can be made to flow into the two spacer cone forming parts through the flow path in the cavity, and the process of injecting the resin material can be simplified in molding in which multiple resin layers are laminated to multiple spacer cone forming parts. Also, since molding can be performed by injecting the resin material into the cavity, the constraints on obtaining a string-like extrusion product as in the conventional molding can be alleviated. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1A is a bottom view of an insulating spacer according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the insulating spacer of FIG. 1A. [Diagram 2] FIG. 2A is a schematic diagram of an insulating spacer molding apparatus according to the first embodiment, and FIG. 2B is a top view of a molding die of the molding apparatus. [Diagram 3] FIG. 2 is an explanatory perspective view of a cavity formed in the molding die. [Figure 4] 4A and 4B are explanatory diagrams of a preparation step in the first embodiment. [Diagram 5] FIG. 4 is an explanatory diagram showing an initial stage of a lamination process in the first embodiment. [Figure 6] FIG. 4 is an explanatory view showing a state after completion of a lamination step in the first embodiment. [Figure 7] FIG. 4 is an explanatory diagram of a demolded state after curing in the first embodiment. [Figure 8] FIG. 4 is an explanatory diagram of a removing step and a finishing step in the first embodiment. [Figure 9] FIG. 11 is a top view of a casting mold according to a modified example of the first embodiment. [Figure 10] FIG. 11 is a bottom view of an insulating spacer according to a second embodiment. [Figure 11] FIG. 11 is a top view of a casting mold according to a second embodiment. [Figure 12] FIG. 13 is a top view of a casting mold according to a modified example of the second embodiment. [Figure 13] FIG. 13 is a top view of a casting mold according to a third embodiment. [Figure 14] FIG. 13 is a top view of a casting mold according to a modification of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Before describing the embodiments of the present invention, the background to how the embodiments of the present invention were arrived at will be described. A conventional gas-insulated switchgear has a structure in which a high-voltage conductor is arranged in a metal sealed container. In this type of gas-insulated switchgear, a solid insulator called an insulating spacer is used to fix the high-voltage conductor in a predetermined position in the sealed container.

[0011] Conventionally, in a commonly used disk-shaped insulating spacer, a high voltage conductor is provided in the center, and the insulating spacer is provided to support the high voltage conductor. A metal flange is attached to the periphery of the insulating spacer, and the insulating spacer is fixed to the sealed container by being sandwiched between the connecting flanges of the sealed container by the metal flange.

[0012] In recent years, there has been a demand for greater economy, and there is a demand for more compact gas-insulated switchgear. In conventional insulating spacers, the electric field concentration in the gas space caused by the difference in the dielectric constant between the insulating gas, which is mainly composed of SF6, and the solid insulating material is an obstacle to compactification. Therefore, in order to achieve compactification, studies are being conducted on reducing the electric field on the surrounding conductor surface and its vicinity, and on the spacer surface and its vicinity, by changing the relative dielectric constant of the cone-shaped insulating spacer in the radial direction.

[0013] In such a cone-shaped insulating spacer, an insulator with a gradient in dielectric constant is used so that the electric field decreases from the portion in contact with the high-voltage conductor or its periphery toward the ground side. In addition to reducing the electric field strength and making the spacer compact by using an insulator with a gradient in dielectric constant, it is required to reduce the burden on facilities and maintain a good appearance from the viewpoint of quality evaluation while alleviating the above-mentioned molding constraints and simplifying the process.

[0014] Hereinafter, a method for forming an insulating spacer according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiment, and can be appropriately modified and implemented within the scope of the present invention. For convenience of explanation, some configurations may be omitted in the following drawings. Below, an insulating spacer according to a first embodiment, an insulating spacer forming device, an insulating spacer forming method, and a second embodiment will be described in that order.

[0015] [First embodiment] Fig. 1A is a bottom view of an insulating spacer according to a first embodiment, and Fig. 1B is a schematic cross-sectional view of the insulating spacer of Fig. 1A. As shown in Fig. 1A, an insulating spacer 10 of this embodiment is a three-phase integrated insulating spacer, and includes three axially shaped central conductors 11. The insulating spacer 10 is formed into a circular outer periphery in accordance with the shape of a sealed container (not shown) of a gas-insulated switchgear to which it is fixed, and a metal flange (not shown) is attached to the outer periphery.

[0016] In addition, the three central conductors 11 are provided corresponding to the R phase, S phase, and T phase that make up the three phases, and for ease of understanding in each drawing, the central conductors 11 are represented by adding the letters "R", "S", and "T".

[0017] The insulating spacer 10 includes three spacer cone portions 12 arranged in a line at a predetermined interval in a linear direction (left-right direction in FIG. 1), and a plate-shaped base portion 13 arranged in a continuous manner around the three spacer cone portions 12. The insulating spacer 10 of this embodiment is arranged in the order of the R-phase spacer cone portion 12, the S-phase spacer cone portion 12, and the T-phase spacer cone portion 12 from left to right.

[0018] 1B, the spacer cone portion 12 is provided around the central conductor 11 to support the central conductor 11. The spacer cone portion 12 is formed in a cone shape with the same axial direction as the central conductor 11, with one surface along the axial direction (the lower surface in FIG. 1B) being a convex surface and the other surface (the upper surface in FIG. 1B) being a concave surface. Thus, in FIG. 1B, the lower end surface of the spacer cone portion 12 is the apex of the cone shape, and the upper end surface is the bottom of the cone shape.

[0019] In the spacer cone portion 12, the first to fifth resin layers 21 to 25 are laminated as a plurality of insulating resin layers whose relative dielectric constants are stepwise different from the convex surface to the concave surface along the axial direction, for example, whose relative dielectric constant decreases stepwise. Thus, the central conductor 11 and the first to fifth resin layers 21 to 25 are arranged in order from the inside to the outside in the radial direction in a substantially concentric shape. The first to fifth resin layers 21 to 25 are configured by a molding method described later so as not to be mixed with each other, and a plurality of insulating resin layers having different relative dielectric constants are laminated with their interfaces substantially parallel to each other. In this embodiment, the fifth resin layer 25 and the base portion 13 are formed of the same resin material so as to have the same relative dielectric constant.

[0020] Next, a molding apparatus 30 for the insulating spacer 10 according to the first embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2A is a schematic diagram of the molding apparatus for the insulating spacer according to the first embodiment. Fig. 2B is a diagram of a molding die of the molding apparatus as viewed from above.

[0021] As shown in Fig. 2A, the molding apparatus 30 for molding the insulating spacer 10 described above includes a molding die 31 and a dispenser 40. The molding apparatus 30 is placed in a tank (not shown) in which the temperature and vacuum level can be controlled. Note that Fig. 2A shows a schematic cross section of the molding die 31, similar to Fig. 1B.

[0022] The molding die 31, which is a die for cast molding, has a lower die 32 located below, and an upper die 34 located above the lower die 32 and forming a cavity 33 between the lower die 32 and the upper die 34. The molding die 31 is formed by combining the lower die 32 and the upper die 34. The molding die 31 is generally a cast mold, but is not limited to a metal mold and may be formed of other materials.

[0023] The molding die 31 is designed to have a shape of the cavity 33 so as to be able to manufacture the above-mentioned insulating spacer 10. In other words, in the molding die 31, the lower die 32 and the upper die 34 form the cavity 33 having a shape corresponding to the three-phase integrated insulating spacer 10 having three spacer cone portions 12.

[0024] The cavity 33 includes three spacer cone portion forming portions 35 corresponding to the three cone-shaped spacer cone portions 12 in the cross-sectional view in Fig. 1B, and a base portion forming portion 36 connected to the upper end of each of the three spacer cone portion forming portions 35. The three spacer cone portion forming portions 35 are arranged side by side in a linear direction (left and right direction in Fig. 2B) which is the diameter direction of the base portion forming portion 36 corresponding to the three spacer cone portions 12. In the cavity 33 of this embodiment, the spacer cone portion forming portion 35 for the R phase, the spacer cone portion forming portion 35 for the S phase, and the spacer cone portion forming portion 35 for the T phase are arranged side by side in this order from left to right.

[0025] The spacer cone portion forming portion 35 has a cone shape that is convex downward. The central portion of the convex bottom surface of the spacer cone portion forming portion 35 forms the apex of the cone shape of the spacer cone portion 12. In other words, the spacer cone portion forming portion 35 is disposed with the apex forming portion of the cone shape on the bottom side. The spacer cone portion forming portion 35 is configured so that the central conductor 11 can be installed by penetrating vertically through it, and an O-ring 37 is provided at the penetrating portion.

[0026] In the upper mold 34, an injection port 38 through which a nozzle 41 of the dispenser 40 can be inserted is formed at a position corresponding to the upper part of the central spacer cone forming part 35 among the three spacer cone forming parts 35 arranged on the left and right. In the present embodiment, the injection port 38 is formed at two positions on the left and right above the central spacer cone forming part 35, but the formation of either one of them may be omitted. The injection port 38 is formed penetrating the upper mold 34 and communicates the inside of the cavity 33 with the outside of the molding die 31. The injection port 38 extends in a direction inclined with respect to the vertical direction, and is formed above the spacer cone forming part 35 along the position where the cone shape of the spacer cone forming part 35 extends. Therefore, the injection port 38 extends in parallel to the inclination angle of the cone shape of the spacer cone forming part 35 according to the inclination angle of the cone shape of the spacer cone forming part 35 at the formation position.

[0027] FIG. 3 is an explanatory perspective view of a cavity formed in the molding die. FIG. 3 illustrates a portion of the cavity 33 where the lower die 32 is formed. As shown in FIG. 3, the cavity 33 further includes two flow paths 39 formed in a slit shape in the lower die 32. The two flow paths 39 extend in the left-right direction in FIG. 3, which is the arrangement direction of the three spacer cone portion forming portions 35. Of the two flow paths 39, one flow path 39 communicates with the spacer cone portion forming portion 35 of the R phase and the spacer cone portion forming portion 35 of the S phase, and the other flow path 39 communicates with the spacer cone portion forming portion 35 of the S phase and the spacer cone portion forming portion 35 of the T phase. Thus, the flow path 39 is provided at a position that connects the spacer cone portion forming portion 35 of the S phase, which is located in the center in the arrangement direction, among the three spacer cone portion forming portions 35, to the spacer cone portion forming portions 35 of the R phase and the spacer cone portion forming portions 35 of the T phase, which are located on both sides in the arrangement direction.

[0028] The flow paths 39 are formed across the entire vertical width of the spacer cone portion forming portions 35 in the lower mold 32. In other words, in the vertical direction, the formation range of the spacer cone portion forming portions 35 in the lower mold 32 and the formation range of the flow paths 39 coincide with each other. A resin material, which will be described later, is injected into the interior of the cavity 33 via a nozzle 41, which will be described later, flows through each of the flow paths 39. Therefore, when the resin material is injected into any of the three spacer cone portion forming portions 35 or the two flow paths 39, the resin material flows into all of them.

[0029] The dispenser 40 is a device capable of injecting a resin material (sometimes called resin) that is the material of the spacer cone portion 12 and the base portion 13 of the insulating spacer 10 in a molten state into the molding die 31. The dispenser 40 includes a nozzle 41, a mixer 42, a pipe for a first resin 43, a pipe for a second resin 44, and a pipe for a hardener 45. The dispenser 40 is disposed above the molding die 31 via a moving device (not shown). The moving device may employ a moving mechanism using a cylinder, a direct-acting motor, a linear motor, a conveyor, a moving stage, a slider, a feed screw structure, or the like. In this embodiment, the dispenser 40 is configured to be movable, but as long as the dispenser 40 and the molding die 31 are configured to be relatively movable, both of them may be movable, or only the molding die 31 may be movable.

[0030] The nozzle 41 discharges the resin material supplied from the mixer 42 from the tip (lower end) and injects the molten resin material into the cavity 33 through the injection port 38 of the molding die 31. The nozzle 41 is formed in a tubular shape extending in a predetermined linear direction, and may be made of metal such as aluminum or iron, or plastic such as silicone or fluororubber, as long as it has enough rigidity to maintain its shape when connected to the mixer 42 at the base end. In this embodiment, the dispenser 40 is arranged so that the extension direction of the nozzle 41 maintains an inclined state parallel to the inclination angle of the above-mentioned cone shape.

[0031] Mixer 42 is supplied with base agents having different relative dielectric constants from first resin pipe 43 and second resin pipe 44, and is supplied with a hardener for reacting with the base agent and hardening it from hardener pipe 45. Mixer 42 supplies the supplied base agent and hardener as a mixed resin material to nozzle 41. A static mixer is used for mixer 42, but a dynamic mixer may also be used.

[0032] A material supplying device (not shown) is connected to each of the pipes 43 to 45 to supply a base resin and a hardener so as to control the amount and time of discharge of the resin material from the nozzle 41. The material supplying device stores two or more types of resins or prepares them into a predetermined composition as necessary, and supplies them to the dispenser 40 under the control of a control device. The material supplying device may be configured to include, for example, a storage tank containing a filler and a thermosetting resin in different ratios, a mixer for mixing them, and a control device for controlling the composition, but is not limited to this configuration.

[0033] Next, a method for forming the insulating spacer 10 according to the embodiment will be described with reference to FIGS. 4 to 8 in addition to FIG.

[0034] In the method for forming the insulating spacer 10 in this embodiment, the steps are carried out in the order of a preparation step, a mold arrangement step, a lamination step, a curing step, a removal step, and a finishing step.

[0035] First, a preparation step is carried out as shown in Figures 4A and 4B. Figures 4A and 4B are explanatory views of the preparation step, with Figure 4A showing a midway stage of the preparation step and Figure 4B showing a completed state of the preparation step.

[0036] In the preparation step, the upper die 34 is removed from the lower die 32 of the molding die 31 to open the molding die 31. In this state, the central conductor 11 is disposed in the cavity 33 of the lower die 32 so as to penetrate through the center of the bottom surface of each of the three spacer cone portion forming portions 35. The central conductor 11 is fixed to the molding die 31 by means of screws or the like.

[0037] After the central conductor 11 is placed, the upper die 34 is placed on the lower die 32 to close the molding die 31. In this state, the O-ring 37 is in close contact with the outer circumferential surface of the central conductor 11 so that the resin material does not leak out of the cavity 33 after it is injected.

[0038] After the preparation step, a die arrangement step is carried out as shown in Fig. 2A. Fig. 2A shows the state after the die arrangement step is completed. In the die arrangement step, the molding die 31 in which the central conductor 11 has been arranged inside the cavity 33 in the preparation step is arranged on a stage (not shown). At this time, the molding die 31 is arranged so that the convex portion of each spacer cone forming portion 35 (the portion forming the apex of the cone-shaped spacer cone portion 12) faces the bottom (lower side).

[0039] After the arrangement step, a lamination step is carried out as shown in Fig. 5 and Fig. 6. In the lamination step, a plurality of resin layers (five layers in this embodiment) are laminated. Fig. 5 is an explanatory diagram showing a state at an early stage of the lamination step. Fig. 6 is an explanatory diagram showing a state after the lamination step is completed.

[0040] 2A shows a state immediately before the lamination step is performed. As shown in FIG. 2A, in the lamination step, first, the dispenser 40 is moved by a moving device (not shown) so that the injection port 38 is disposed below the nozzle 41 of the dispenser 40. At this time, the nozzle 41 is inclined with respect to the vertical direction so as to have the same angle as the inclination angle of the injection port 38 disposed below the nozzle 41 (the same as the inclination angle of the cone shape of the spacer cone part forming part 35). As a result, the injection port 38 and the part extending parallel to the inclination angle of the spacer cone part forming part 35 communicating with the injection port 38 are disposed on the same straight line as the nozzle 41.

[0041] After the molding die 31 is positioned as shown in Fig. 2A, the dispenser 40 is moved as shown in Fig. 5, whereby the nozzle 41 is inserted into the injection port 38 and the S-phase spacer cone portion forming portion 35. The insertion amount of the nozzle 41 is controlled according to the formation position of the first resin layer 21 to be laminated first.

[0042] Thereafter, in dispenser 40, the base agent and the curing agent supplied from each of pipes 43 to 45 are mixed in mixer 42 to form a resin material, which is then supplied to nozzle 41. The mixed resin material is then discharged from nozzle 41, and the resin material is injected into the interior of S-phase spacer cone portion forming portion 35 in cavity 33.

[0043] The injected resin material flows into the R-phase and T-phase spacer cone portion forming portions 35 through two flow paths 39 communicating with the S-phase spacer cone portion forming portion 35, and the resin material flows into the three spacer cone portion forming portions 35. When the resin material corresponding to the required thickness of the first resin layer 21 to be laminated is injected, the three spacer cone portion forming portions 35 and the resin material flowing into the two flow paths 39 are formed so that their height positions (liquid surface positions) are aligned at the same vertical position. As a result, the first resin layer 21 is laminated inside the cavity 33.

[0044] After laminating the first resin layer 21, the dispenser 40 is moved, and the vertical position of the tip of the nozzle 41 is adjusted to a position according to the formation position of the second resin layer 22 (see FIG. 5) to be laminated next. Thereafter, the same process as the lamination of the first resin layer 21 described above is repeated four more times according to the first to fifth resin layers 21 to 25. In other words, the resin material is injected five times through the nozzle 41 according to the number of laminations of the first to fifth resin layers 21 to 25, which are five layers. As a result, the first to fifth resin layers 21 to 25 are laminated in the vertical direction to reach the state shown in FIG. 6, and the lamination process is completed. The fifth resin layer 25, which is the last resin layer, is formed integrally and continuously including the base portion 13.

[0045] After the lamination step, a curing step is carried out as shown in Fig. 7. Fig. 7 is an explanatory diagram of the demolded state after curing. In the curing step, the molding die 31 after the lamination step shown in Fig. 6 is stored in a thermostatic chamber at a predetermined temperature and heated for a predetermined time, thereby carrying out primary curing of each of the laminated resin layers 21 to 25. After the predetermined time of curing, as shown in Fig. 7, demolding is carried out at the molding die 31, and the insulating spacer 10 is formed.

[0046] In the insulating spacer 10 after demolding, the remaining portion 14 is formed by the resin material that has flowed into each flow path 39 and hardened. Since each flow path 39 is formed in a slit shape, the remaining portion 14 is formed in a thin piece shape that continues to the lower surface of the base portion 13 while connecting the two spacer cone portions 12.

[0047] After the curing step, a removing step is carried out as shown in Fig. 8. Fig. 8 is an explanatory diagram of the removing step and the finishing step. In the removing step, an external force is applied to the remaining portion 14 formed in the insulating spacer 10, and the remaining portion 14 is broken at the boundary position 14a between the spacer cone portion 12 and the base portion 13, thereby removing the remaining portion 14 from the insulating spacer 10.

[0048] After the removing step, a finishing step is carried out. In the finishing step, if any protrusions such as burrs remain in the removed portion of the remaining portion 14 in the spacer cone portion 12 and the base portion 13 (shown by the two-dot chain line in FIG. 1A), the protrusions are removed. Next, the removed portion of the remaining portion 14 is polished using a polisher, abrasive paper, abrasives, or the like. Thereafter, the insulating spacer 10 is stored again in a thermostatic chamber at a predetermined temperature for secondary hardening, and is heated to a predetermined temperature, taken out, and slowly cooled to complete the insulating spacer 10. The finishing step may be omitted if no protrusions or the like are present in the removed portion of the remaining portion 14 and a smooth finished surface is formed.

[0049] Here, the resin used in the molding method of the present embodiment may be an insulating resin that is capable of being heated and cured to function as the insulating spacer 10, has a relative dielectric constant of 2 to 40, and is in a fluid state under injection conditions. Specifically, it may be a thermosetting resin containing a filler, and the thermosetting resin may be, for example, an epoxy resin, a maleimide resin, a cyanate resin, or a mixture thereof.

[0050] The thermosetting resin is preferably an epoxy resin. The epoxy resin preferably contains an epoxy resin base, a curing agent, and optionally a curing accelerator. The epoxy resin base can be an aliphatic epoxy, an alicyclic epoxy, or a mixture thereof. Examples of the aliphatic epoxy resin include, but are not limited to, bisphenol A type epoxy, bisphenol F type epoxy, bisphenol AD ​​type epoxy, biphenyl type epoxy, cresol novolac type epoxy, and polyfunctional epoxy having three or more functional groups. These can be used alone or in a mixture of two or more types. Examples of the alicyclic epoxy resin include, but are not limited to, monofunctional epoxy, bifunctional epoxy, and polyfunctional epoxy having three or more functional groups. The alicyclic epoxy resin can also be used alone or in a mixture of two or more different alicyclic epoxy resins.

[0051] The curing agent for the thermosetting resin is not particularly limited as long as it can react with the epoxy resin base and cure, but it is preferable to use an acid anhydride curing agent.The acid anhydride curing agent can be, for example, an aromatic acid anhydride, specifically phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, etc. Alternatively, it can be cyclic aliphatic acid anhydride, specifically tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, etc., or aliphatic acid anhydride, specifically succinic anhydride, polyadipic anhydride, polysebacic anhydride, polyazelaic anhydride, etc., but is not particularly limited.In addition, as the curing accelerator, it can be appropriately used imidazole or its derivatives, tertiary amines, boric acid esters, Lewis acids, organometallic compounds, organic acid metal salts, etc., but is not particularly limited.

[0052] The filler is contained in the resin in a composition and amount that makes the relative dielectric constant of the resin to be used a desired relative dielectric constant. An insulating inorganic filler can be used as the filler. Alumina, silica, dolomite, etc., which have a relative dielectric constant of less than 10, can be used as a filler for preparing a resin with a relatively low dielectric constant, and titanium oxide, barium titanate, strontium titanate, etc. can be used as a filler for preparing a resin with a relatively high dielectric constant, but the filler is not limited to these.

[0053] In this embodiment, the composition of the resin to be injected can be appropriately determined by a person skilled in the art so as to achieve the desired physical properties such as the dielectric constant and heat resistance by using the thermosetting resin base, the curing agent, and optionally the curing accelerator and inorganic filler. The desired value of the dielectric constant is preferably designed so that the ratio of the dielectric constant of the resin with the lowest dielectric constant to the resin with the highest dielectric constant is 3 to 4. In addition, it is preferable to design the difference in the dielectric constant between adjacent resins that are stacked in the mold and in contact with each other to be, for example, less than 1. If the difference in the dielectric constant between adjacent resins is too large, an inconvenience such as electric field concentration on the surface of the spacer at the interface may occur.

[0054] In the molding method of the present embodiment, two or more resins having different dielectric constants are used, but the types of resins are preferably three or more. Therefore, the number of types may be four to ten or more. That is, the dielectric constant of the resin to be injected may differ in at least two stages, and may differ in three to ten stages or more. These two or more different resins can be prepared to a desired composition by a resin preparation unit (not shown) connected to the dispenser 40. Then, a control device (not shown) sends a resin of a predetermined composition in a predetermined amount to the dispenser 40 so that it can be injected into the molding die 31. According to one embodiment, the order of injection of the two or more resins having different dielectric constants may be in descending order of dielectric constant. Alternatively, the order of injection may be in ascending order of dielectric constant or in ascending order of dielectric constant, large, small, and medium, and is not particularly limited. The present invention is not limited to a specific embodiment regarding the order of injection of the two or more resins having different dielectric constants.

[0055] Each step of the molding method of this embodiment is carried out in a tank where the temperature and vacuum level can be controlled, and the pressure is preferably about 10 Torr (1.3 KPa) or less. The pressure during casting is preferably about 10 Torr (1.3 KPa) to 30 Torr (3.9 KPa) or less, and this pressure is preferably maintained for about 1 to 3 minutes. By keeping the pressure in this range, air bubbles can be eliminated.

[0056] As described above, according to the first embodiment, the resin material can be flowed into the three spacer cone forming parts 35 through the flow path 39 in the cavity 33 at approximately the same timing. This reduces the number of times the nozzle 41 is moved in and out of the cavity 33 during molding in which the five resin layers 21 to 25 are laminated in each of the three spacer cone forming parts 35, simplifying the injection of the resin material. In addition, since molding can be performed by injecting the resin material into the cavity 33, the constraint of obtaining a string-like extrusion product as in the past during molding can be alleviated. Furthermore, since it is possible to mold an insulating spacer 10 having a cone shape and a gradient-changing relative dielectric constant, it is possible to reduce the size of the insulating spacer 10 and reduce the electric field in the creeping direction component at the spacer cone part 12.

[0057] In addition, since the flow paths 39 are formed in a slit shape, the remaining portion 14 remaining after the curing step can be formed in a thin piece shape, and the remaining portion 14 can be easily removed in a short time in the removing step. Furthermore, since the flow paths 39 are formed across the entire vertical width of the spacer cone portion forming portion 35 in the lower mold 32, the injected resin material can be poured into the flow paths 39 in all laminations of the first to fifth resin layers 21 to 25. Therefore, the resin material can be injected and laminated in the same manner in all of the first to fifth resin layers 21 to 25, and the process can be simplified.

[0058] Furthermore, in an insulating spacer 10 in which three spacer cone portions 12 are arranged in a linear direction, by forming the above-mentioned two flow paths 39 in the cavity 33, the three spacer cone portion forming portions 35 can be made to communicate with each other via the two flow paths 39.

[0059] Here, in the first embodiment, one flow path 39 is formed on each of the left and right sides of the spacer cone portion forming portion 35 of the S phase, but the number of such flow paths 39 may be multiple as shown in Fig. 9. Fig. 9 is a top view of a molding die of a modified example of the first embodiment.

[0060] In Fig. 9, two flow paths 39 are formed to communicate with the spacer cone portion forming portion 35 of the R phase and the spacer cone portion forming portion 35 of the S phase, and two flow paths 39 are formed to communicate with the spacer cone portion forming portion 35 of the S phase and the spacer cone portion forming portion 35 of the T phase. In this manner, a plurality of flow paths 39 may be formed side by side between the connected spacer cone portion forming portions 35. By providing a plurality of flow paths 39 as in Fig. 9, the flow rate per unit time of the resin material flowing through the flow paths 39 to the other spacer cone portion forming portions 35 can be increased, and the injection time of the resin material can be shortened.

[0061] Next, other embodiments of the present invention will be described. In the following description, the same reference numerals may be used for components that are the same as or equivalent to those in the embodiment described before the embodiment described, and the description may be omitted or simplified.

[0062] [Second embodiment] A second embodiment of the present invention will be described with reference to Figs. 10 and 11. Fig. 10 is a bottom view of an insulating spacer according to the second embodiment. Fig. 11 is a top view of a molding die of the second embodiment. In the second embodiment, the positions at which the three spacer cone portions 12 are formed are changed from those in the first embodiment. As shown in Fig. 10, the insulating spacer 10 of the second embodiment has three spacer cone portions 12 arranged side by side in the circumferential direction of the base portion 13. In Fig. 11, the three spacer cone portions 12 are arranged side by side at equal angles (120°) around a central position parallel to the axial direction of the central conductor 11 (direction perpendicular to the paper surface in Fig. 11).

[0063] As shown in Fig. 11, in the molding die 31 of the second embodiment, three spacer cone portion forming portions 35 are formed lined up in the circumferential direction corresponding to the three spacer cone portions 12. Therefore, in Fig. 11, the three spacer cone portion forming portions 35 are arranged at equal angular intervals (120°) around a central position parallel to the direction perpendicular to the paper surface in Fig. 11.

[0064] The cavity 33 of the second embodiment is provided in the lower mold 32 in a shape branching in three directions, and is provided with flow paths 52 that communicate with all three spacer cone portion forming portions 35. Thus, each of the three spacer cone portion forming portions 35 communicates with the other two spacer cone portion forming portions 35 via the flow paths 52. Note that, although the illustration shows a case in which the injection port 38 is formed near the position where each of the three spacer cone portion forming portions 35 communicates with the flow paths 52, it may be changed to or added to a position in the flow path 52 where it branches in three directions.

[0065] As described above, even in the case of an insulating spacer 10 in which three spacer cone portions 12 are arranged in the circumferential direction, by forming the above-mentioned flow path 52 in the cavity 33, it is possible to make the three spacer cone portion forming portions 35 communicate with each other.

[0066] In the second embodiment shown in Fig. 11, the flow paths 52 are formed from the branching position to each of the three spacer cone portion forming portions 35, but the present invention is not limited to this and may be configured as shown in Fig. 12, for example. Fig. 12 is a top view of a molding die according to a modification of the second embodiment. In the modification of Fig. 12, multiple flow paths 52 (two paths each) are formed from the branching position to each of the three spacer cone portion forming portions 35.

[0067] [Third embodiment] A third embodiment of the present invention will be described with reference to Fig. 13. Fig. 13 is a top view of the molding die of the second embodiment. In the third embodiment, the positions at which the three spacer cone forming portions 35 are formed in the cavity 33 are the same as those in the second embodiment, but the shape and the position at which the flow paths 53 are formed are changed. In the flow paths 53 of the third embodiment, each of the three spacer cone forming portions 35 communicates with the other two spacer cone forming portions 35 via two flow paths 53. Thus, the cavity 33 of the third embodiment has three flow paths 53.

[0068] Of the three flow paths 53, one flow path 53 communicates with the spacer cone portion forming portion 35 for the S phase and the spacer cone portion forming portion 35 for the R phase. In addition, of the three flow paths 53, the other flow path 53 communicates with the spacer cone portion forming portion 35 for the R phase and the spacer cone portion forming portion 35 for the T phase, and still another flow path 53 communicates with the spacer cone portion forming portion 35 for the T phase and the spacer cone portion forming portion 35 for the S phase.

[0069] Even in the third embodiment, for an insulating spacer 10 having three spacer cone portions 12 arranged in the circumferential direction, by forming the above-mentioned flow path 53 in the cavity 33, it is possible to make the three spacer cone portion forming portions 35 communicate with each other.

[0070] Here, in the third embodiment shown in Fig. 13, one flow passage 53 is formed to connect each of the two spacer cone forming portions 35, but as shown in Fig. 14, a plurality of such flow passages 53 may be formed. Fig. 14 is a top view of a molding die of a modified example of the third embodiment.

[0071] 14, two flow paths 53 are formed communicating with the spacer cone portion forming portion 35 of the S phase and the spacer cone portion forming portion 35 of the R phase. In addition, two flow paths 53 are formed communicating with the spacer cone portion forming portion 35 of the R phase and the spacer cone portion forming portion 35 of the T phase, and two flow paths 53 are formed communicating with the spacer cone portion forming portion 35 of the T phase and the spacer cone portion forming portion 35 of the S phase. In this manner, a plurality of flow paths 53 may be formed in a line between the connected spacer cone portion forming portions 35.

[0072] The present invention is not limited to the above-described embodiments, and can be modified in various ways. In the above-described embodiments, the size, shape, orientation, and the like shown in the accompanying drawings are not limited to these, and can be modified as appropriate within the scope of the effects of the present invention. In addition, the present invention can be modified as appropriate without departing from the scope of the object of the present invention.

[0073] In the three-phase integrated insulating spacer 10 in each of the above embodiments, the layout of the three central conductors 11 and the three spacer cone portions 12 around them may be changed. For example, in the first embodiment in which the three spacer cone portions 12 are arranged in a straight line, the center position of the central spacer cone portion 12 and the center position of the base portion 13 may be different. In the second and third embodiments in which the three spacer cone portions 12 are arranged at predetermined angles (120°) around the center position, the center position may be different from the center position of the base portion 13. In the second and third embodiments in which the three spacer cone portions 12 are arranged in the circumferential direction, the spacer cone portions 12 may be arranged at any angle interval around the center position, instead of at equal angles, depending on the arrangement angle of the conductors in the gas-insulated switchgear. In this case, the layout of the spacer cone portion forming portion 35 in the molding die 31 is also changed depending on the layout of the spacer cone portions 12.

[0074] In addition, in each of the above embodiments, the insulating spacer 10 has three spacer cone portions 12, but the number of spacer cone portions 12 may be more than one, and may be changed to two, four or more. In this case, the number of spacer cone portion forming portions 35 formed in the molding die 31 is changed according to the number of spacer cone portions 12 formed.

[0075] Furthermore, the number of resin layers laminated in the insulating spacer 10 is not limited to five layers in the above embodiments and may be increased or decreased as appropriate, and the number of times the resin material is injected in the lamination process is changed depending on the number of resin layers.

[0076] Furthermore, in the second and third embodiments, injection port 38 is formed in each spacer cone portion forming portion 35, but it is sufficient that at least one injection port 38 is formed in casting mold 31. [Explanation of symbols]

[0077] 10: Insulating spacer 11: Center conductor 12: Spacer cone part 14:Residual part 21: First resin layer (resin layer) 22: Second resin layer (resin layer) 23: Third resin layer (resin layer) 24: 4th resin layer (resin layer) 25: 5th resin layer (resin layer) 30: Molding equipment 31: Molding mold 32: Lower mold 33: Cavity 34: Upper mold 35: Spacer cone forming section 39: Flow path 41: Nozzle 52: Flow path 53: Flow path

Claims

1. A mold for forming an insulating spacer, the mold including a plurality of spacer cone portions formed in a cone shape around a central conductor while supporting the central conductor, a lower mold and an upper mold for forming a cavity having a shape corresponding to the insulating spacer, The cavity includes a plurality of spacer cone portion forming portions corresponding to the plurality of spacer cone portions; a flow path formed in a slit shape communicating with at least two of the spacer cone forming portions, through which a resin material injected into the interior of the cavity flows.

2. The spacer cone portion forming portion is disposed with the cone-shaped apex forming portion on the bottom side, 2. The mold for forming an insulating spacer according to claim 1, wherein the flow path is formed across the entire vertical width of the spacer cone portion forming portion of the lower mold.

3. 3. The mold for forming an insulating spacer according to claim 1, wherein a plurality of the flow paths are formed in parallel between the spacer cone forming portions that are connected to each other.

4. The three spacer cone portions are arranged in a linear direction by the insulating spacer, the spacer cone portion forming portion is formed in three portions aligned in a linear direction corresponding to the three spacer cone portions, 3. The insulating spacer molding die according to claim 1, wherein the flow path is provided at a position connecting the spacer cone portion forming portion in the center in the arrangement direction of the three spacer cone portion forming portions to the spacer cone portion forming portions on both sides in the arrangement direction.

5. The insulating spacer includes three spacer cone portions arranged in a circumferential direction, the spacer cone portion forming portion is formed in three portions aligned in the circumferential direction corresponding to the three spacer cone portions, 3. The mold for forming an insulating spacer according to claim 1, wherein the flow path is provided in a shape branched in three directions so as to communicate with all three of the spacer cone forming portions.

6. The insulating spacer includes three spacer cone portions arranged in a circumferential direction, the spacer cone portion forming portion is formed in three portions aligned in the circumferential direction corresponding to the three spacer cone portions, 3. The mold for forming an insulating spacer according to claim 1, wherein each of the three spacer cone forming portions is connected to the other two spacer cone forming portions via two of the flow paths.

7. 3. A molding method for an insulating spacer including a plurality of spacer cone portions formed into a cone shape around a central conductor while supporting the central conductor, using the molding die according to claim 1 or 2 and a nozzle for injecting a resin material into the cavity of the molding die, comprising: a mold placement step of placing the molding die in the cavity with the apex forming portion of the cone shape facing downward; a lamination process in which the resin material is injected into the cavity through the nozzle a plurality of times, and the resin material is caused to flow into all of the plurality of spacer cone portion forming portions through the flow passage, thereby laminating a plurality of resin layers in a vertical direction; a curing step in which the resin layer laminated in the lamination step is cured and the insulating spacer is released from the molding die; a removing step of removing a residual portion of the insulating spacer, which is formed of the resin material hardened in the flow path, from the spacer cone portion.

8. 8. The method for forming an insulating spacer according to claim 7, further comprising a finishing step of polishing the removed portion of the remaining portion of the spacer cone portion after the removing step is performed.

Images