Method for molding insulating spacers

Abstract

The present invention addresses the problem of simplifying processes and easing restrictions on molding. The present invention provides a method for molding an insulating spacer (10) which comprises a cone-shaped spacer cone part (12) that is provided around a center conductor (11) so as to support the center conductor. In this molding method, a casting mold (31) that comprises a lower mold (32) and an upper mold (34), which form a cavity (33) that has a shape corresponding to the insulating spacer, and a nozzle (41) for injecting a resin material into the cavity are used. This molding method executes a stacking step for stacking a plurality of resin layers by repeatedly performing a pre-injection moving step, an injection step and a post-injection moving step. In the pre-injection moving step, the nozzle is inserted into the cavity by moving the casting mold in a state where the nozzle is stopped. In the injection step, the resin material is injected into the cavity from the nozzle. In the post-injection moving step, the nozzle is taken out from the cavity by moving the casting mold in a state where the nozzle is stopped.

Description

Technical Field

[0001] The present invention particularly relates to a method for molding an insulating spacer used in a gas-insulated switchgear.

Background Art

[0002] Patent Document 1 discloses an insulating spacer used for supporting a conductor in a metal container of a gas-insulated equipment. Such an 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 maintains a higher dielectric constant than the ground side. With such a configuration, it is intended to provide a more compact insulating spacer while satisfying the insulation performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, there are problems that a step of obtaining a string-like extruded product from a material in which a thermosetting resin and a filler are kneaded, and a step of putting the string-like extruded product into the lower mold of the insulating spacer molding die and sequentially swirling and filling and supplying it are required, and the steps become complicated. Further, Patent Document 1 has a molding constraint that the supply of the filler is linearly increased and decreased with the material for obtaining the string-like extruded product to continuously extrude the string-like extruded product, and the extrusion cannot be interrupted.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a method for molding an insulating spacer capable of simplifying the steps and relaxing the constraints in molding.

Means for Solving the Problems

[0006] A method for molding an insulating spacer according to one aspect of the present invention is a method for molding an insulating spacer comprising at least one cone-shaped spacer cone portion that supports a central conductor and is provided around the central conductor, wherein the method uses a casting mold having a lower mold and an upper mold that form a cavity of a shape corresponding to the insulating spacer, and a nozzle for injecting resin material into the cavity, and repeats a mold placement step of positioning the casting mold with the top forming portion of the cone shape in the cavity facing downwards, a pre-injection movement step, an injection step, and a post-injection movement step. The method comprises a lamination step of stacking multiple resin layers, and a curing step of hardening the resin layers stacked in the lamination step and releasing the insulating spacer from the casting mold, wherein the pre-injection moving step involves moving the casting mold with the nozzle stopped to insert the nozzle into the cavity, the injection step involves injecting the resin material from the nozzle into the cavity, and the post-injection moving step involves moving the casting mold with the nozzle stopped to remove the nozzle from the cavity. [Effects of the Invention]

[0007] According to the present invention, since the injection process is repeated to laminate multiple resin layers, the constraint of obtaining a string-like extruded product during molding, as in the conventional method, can be alleviated, and the process of injecting resin material into a casting mold can be simplified. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1A is a view of the insulating spacer according to the first embodiment from below, and Figure 1B is a schematic representation of the cross-section of the insulating spacer in Figure 1A. [Figure 2] Figure 2A is a schematic diagram of the molding apparatus for insulating spacers according to the first embodiment, and Figure 2B is a view of the casting mold for the molding apparatus from above. [Figure 3] Figures 3A and 3B are explanatory diagrams of the preparation process in the first embodiment. [Figure 4] This is an explanatory diagram of the pre-injection transfer process in the first embodiment. [Figure 5] This is an explanatory diagram of the injection process in the first embodiment. [Figure 6] This is an explanatory diagram of the post-injection transfer process in the first embodiment. [Figure 7] This is an explanatory diagram of the rotational movement process in the first embodiment. [Figure 8] This is an explanatory diagram showing the state at an intermediate stage of the lamination process in the first embodiment. [Figure 9] This is an explanatory diagram showing the state after the completion of the lamination process in the first embodiment. [Figure 10] This is an explanatory diagram of the mold release state after curing in the first embodiment. [Figure 11] This is an explanatory diagram of the preparation process in the second embodiment. [Figure 12] This is an explanatory diagram of the mold placement process and the pre-injection movement process in the second embodiment. [Figure 13] This is an explanatory diagram of the pre-injection transfer process and the injection process in the second embodiment. [Figure 14] This is an explanatory diagram of the post-injection transfer process in the second embodiment. [Figure 15] This is an explanatory diagram of the rotational movement process in the second embodiment. [Figure 16] This is an explanatory diagram showing the state at an intermediate stage of the lamination process in the second embodiment. [Figure 17] This is an explanatory diagram showing the state at an intermediate stage of the lamination process in the second embodiment. [Figure 18] This is an explanatory diagram showing the state after the completion of the lamination process in the second embodiment. [Figure 19] Figure 19A is a view of the modified insulating spacer from below, and Figure 19B is a view of the modified casting mold from above. [Modes for carrying out the invention]

[0009] Before describing embodiments of the present invention, the background leading to these embodiments will be explained. As a conventional gas-insulated switchgear, a structure in which a high-voltage conductor is disposed in a metal sealed container is known. In such a gas-insulated switchgear, a solid insulator called an insulating spacer for fixing the high-voltage conductor to a predetermined position in the sealed container is used.

[0010] Conventionally, in a generally used disk-shaped insulating spacer, a high-voltage conductor is provided at the central portion, and the insulating spacer is provided to support the high-voltage conductor. A metal flange is attached around 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.

[0011] In recent years, as more economical efficiency is required, the gas-insulated switchgear is desired to be made more compact. In a conventional insulating spacer, electric field concentration in a gas space due to the difference in dielectric constant between an insulating gas mainly composed of SF6 and a solid insulator has been an obstacle to compactification. Therefore, in order to achieve compactification, studies have been made to reduce the electric field in the creeping direction component on the surface thereof by changing the relative dielectric constant of the cone-shaped insulating spacer in the radial direction.

[0012] In such a cone-shaped insulating spacer, an insulator whose relative dielectric constant slopes so that the relative dielectric constant decreases from the portion contacting the high-voltage conductor toward the ground side is adopted. In such an insulating spacer, in addition to reducing the electric field strength and achieving compactification by the insulator with a sloping relative dielectric constant, it is required to reduce the equipment load and maintain a good appearance from the viewpoint of quality evaluation while relaxing the above-described molding constraints and simplifying the process.

[0013] Hereinafter, a method for molding an insulating spacer according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments, and can be appropriately modified and implemented within the scope without changing the gist thereof. In the following drawings, for convenience of explanation, some configurations may be omitted. Hereinafter, an insulating spacer, a molding apparatus for an insulating spacer, a method for molding an insulating spacer, and a second embodiment according to the first embodiment will be described in this order.

[0014] [First Embodiment] Figure 1A is a view of the insulating spacer according to the first embodiment from below, and Figure 1B is a schematic representation of the cross-section of the insulating spacer in Figure 1A. As shown in Figure 1A, the insulating spacer 10 of this embodiment is a three-phase integrated insulating spacer and is equipped with three central conductors 11 that form an axis shape. The insulating spacer 10 is formed in a circular outer circumference shape according to the shape of the sealed container (not shown) of the gas-insulated switchgear to which it is fixed, and a metal flange (not shown) is attached to the outer circumference.

[0015] Furthermore, the three central conductors 11 are provided according to the R, S, and T phases that constitute the three phases, and to facilitate understanding in each drawing, the letters "R", "S", and "T" are attached to the central conductors 11.

[0016] The insulating spacer 10 comprises three spacer cone portions 12 arranged at equal angles (120°) around a central position C1 parallel to the axial direction of the central conductor 11, and a plate-shaped base portion 13 arranged in a series around the three spacer cone portions 12.

[0017] As shown in Figure 1B, the spacer cone portion 12 supports the central conductor 11 and is provided around 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 Figure 1B) being convex and the other surface (the upper surface in Figure 1B) being concave. Therefore, in Figure 1B, the lower end surface of the spacer cone portion 12 is the top of the cone shape, and the upper end surface is the bottom of the cone shape.

[0018] In the spacer cone portion 12, the first to fifth resin layers 21 to 25 are laminated along the axial direction, from the convex surface to the concave surface, with the relative permittivity varying in stages, for example, decreasing in stages. Thus, the central conductor 11 and the first to fifth resin layers 21 to 25 are arranged in order in a substantially concentric manner from the radial inside to the outside. The first to fifth resin layers 21 to 25 are configured so as not to mix with each other by a molding method described later, resulting in a state where multiple insulating resin layers with different relative permittivity are laminated with their interfaces substantially parallel. In this embodiment, the fifth resin layer 25 and the base portion 13 are formed from the same resin material to have the same relative permittivity.

[0019] Next, the molding apparatus 30 for the insulating spacer 10 according to the first embodiment will be described with reference to Figure 2. Figure 2A is a schematic configuration diagram of the molding apparatus for the insulating spacer according to the first embodiment. Figure 2B is a view of the casting mold of the molding apparatus from above.

[0020] The molding apparatus 30 for forming the insulating spacer 10 described above comprises a casting mold 31, a dispenser 40, and a moving device 50, as shown in Figure 2A. The molding apparatus 30 is placed in a tank (not shown) where the temperature and vacuum level can be controlled. In Figure 2A, the cross-section of the casting mold 31 is schematically represented, similar to Figure 1B.

[0021] The casting mold 31, which serves as a mold for casting, has a lower mold 32 located below it and an upper mold 34 located above the lower mold 32, forming a cavity 33 between them. The casting mold 31 is constructed by combining the lower mold 32 and the upper mold 34. Although the casting mold 31 is generally a casting mold, it is not limited to a metal mold and may be constructed from other materials.

[0022] The casting mold 31 is designed with a cavity 33 shape that allows for the manufacture of the aforementioned insulating spacer 10. In other words, the casting mold 31 uses the lower mold 32 and the upper mold 34 to form a cavity 33 with a shape corresponding to the three-phase integrated insulating spacer 10, which has three spacer cone portions 12.

[0023] The cavity 33 comprises three spacer cone forming sections 35 corresponding to the three cone-shaped spacer cone sections 12 as seen in cross-section in Figure 1B, and a base forming section 36 connected to the upper end of each of the three spacer cone forming sections 35. The three spacer cone forming sections 35 are arranged at equal angles (120°) around a central axis C2 (axis) that extends vertically in accordance with the three spacer cone sections 12 (see Figure 2B).

[0024] The spacer cone forming portion 35 has a convex shape that is convex downwards. The central part of the convex bottom surface of the spacer cone forming portion 35 forms the top of the cone shape of the spacer cone portion 12. The central conductor 11 can be installed by passing through the spacer cone forming portion 35 from top to bottom, and an O-ring 37 is provided at this passing portion.

[0025] In the upper mold 34, injection channels 38 are formed at positions corresponding to the above of each of the three spacer cone forming sections 35, into which the nozzle 41 of the dispenser 40 (described later) can be inserted. The injection channels 38 are formed through the upper mold 34 and connect the inside of the cavity 33 to the outside of the casting mold 31. The injection channels 38 extend in a direction inclined with respect to the vertical direction and are formed above the spacer cone forming section 35 along the extension of the cone shape of the spacer cone forming section 35. Therefore, at their formation positions, the injection channels 38 extend parallel to the inclination angle θ corresponding to the inclination angle θ of the cone shape in the spacer cone forming section 35.

[0026] The dispenser 40 is a device capable of injecting molten resin material (sometimes referred to as resin) into the casting mold 31, which will be the material for the spacer cone portion 12 and the base portion 13 of the insulating spacer 10. The dispenser 40 includes a nozzle 41, a mixer 42, a first resin pipe 43, a second resin pipe 44, and a hardener pipe 45. The dispenser 40 is fixedly positioned above the casting mold 31 via a support structure (not shown), such as a frame.

[0027] The nozzle 41 discharges the resin material supplied from the mixer 42 from its tip (lower end) and injects the molten resin material into the cavity 33 through the injection channel 38 of the casting mold 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 of plastic such as silicone or fluororubber, as long as it has sufficient rigidity to maintain its shape while connected to the mixer 42 at its base end. In this embodiment, the dispenser 40 is installed so as to maintain an inclined state in which the extension direction of the nozzle 41 is parallel to the inclination angle θ described above.

[0028] Mixer 42 receives main components with different dielectric constants from the first resin piping 43 and the second resin piping 44, and a curing agent that reacts with the main components and hardens from the curing agent piping 45. Mixer 42 supplies the supplied main components and curing agent as a mixed resin material to the nozzle 41. A static mixer is used for mixer 42, but a dynamic mixer may also be used.

[0029] Each pipe 43 to 45 is connected to a material supply device (not shown) that supplies a main agent and a hardener so as to control the discharge amount and discharge time of the resin material from the nozzle 41. The material supply device stores two or more types of resin or prepares them to a predetermined composition as needed, and supplies them to the dispenser 40 under the control of a control device. The material supply device may, for example, include a storage tank containing filler and thermosetting resin in different proportions, a mixing device for mixing them, and a control device for controlling the composition, but is not limited to this configuration.

[0030] The moving device 50 includes a horizontal moving device 51, a vertical moving device 52, and a rotational moving device 53.

[0031] The horizontal movement device 51 can be exemplified as a roller conveyor that moves the casting mold 31 horizontally in the left-right direction (horizontal direction) while supporting the casting mold 31 from below. The vertical movement device 52 can be exemplified as a plurality of power cylinders that support the casting mold 31 and the horizontal movement device 51 so that they can move vertically. The rotary movement device 53 can be exemplified as a rotary stage that supports the casting mold 31, the horizontal movement device 51 and the vertical movement device 52 so that they can move in the rotational direction, and in this embodiment, it rotates around an axis parallel to the vertical direction.

[0032] The illustrated moving devices 51 to 53 are illustrative examples, and their configurations are not particularly limited as long as they can realize the operation using the molding method described below. Therefore, the horizontal moving device 51 and the vertical moving device 52 can employ moving mechanisms using cylinders, linear motors, conveyors, moving stages, sliders, lead screw structures, etc., and the rotary moving device 53 can employ other configurations that allow the supporting device or structure to rotate.

[0033] Next, the molding method for the insulating spacer 10 according to the embodiment will be described with reference to Figures 3 to 10, in addition to Figure 2.

[0034] In this embodiment, the molding method for the insulating spacer 10 is carried out in the following order: preparation step, mold placement step, lamination step, and curing step.

[0035] First, a preparation process is carried out as shown in Figures 3A and 3B. Figures 3A and 3B are explanatory diagrams of the preparation process, with Figure 3A showing an intermediate stage of the preparation process and Figure 3B showing the completed state of the preparation process.

[0036] In the preparation process, the upper mold 34 is removed from the lower mold 32 of the casting mold 31, opening the casting mold 31. In this state, the central conductor 11 is positioned to pass through the center of the bottom surface of each of the three spacer cone forming sections 35 in the cavity 33 of the lower mold 32. The central conductor 11 is fixed to the casting mold 31 by screws or the like.

[0037] After positioning the central conductor 11, the upper mold 34 is placed on top of the lower mold 32 to close the casting mold 31. In this state, the O-ring 37 is in close contact with the outer surface of the central conductor 11, preventing the resin material from leaking out of the cavity 33 after injection.

[0038] After the preparation process, the mold placement process is carried out as shown in Figure 2A. Figure 2A shows the state after the mold placement process is completed. In the mold placement process, the casting mold 31, in which the central conductor 11 was placed inside the cavity 33 in the preparation process, is placed on the horizontal moving device 51 of the moving device 50. At this time, the casting mold 31 is positioned so that the convex portion of each spacer cone forming portion 35 (the top forming portion of the cone-shaped spacer cone portion 12) is on the lower side.

[0039] After the placement process, a lamination process is carried out as shown in Figures 4 to 9. The lamination process consists of a pre-injection movement process, an injection process, a post-injection movement process, and a rotational movement process, which constitute one cycle. Multiple resin layers (five layers in this embodiment) are laminated by repeating this cycle multiple times. The resin materials are laminated in order from those with the highest dielectric constant. Figure 4 is an explanatory diagram of the pre-injection movement process. Figure 5 is an explanatory diagram of the injection process. Figure 6 is an explanatory diagram of the post-injection movement process. Figure 7 is an explanatory diagram of the rotational movement process. Figure 8 is an explanatory diagram showing the state at an intermediate stage of the lamination process. Figure 9 is an explanatory diagram showing the state after the lamination process is completed.

[0040] Figure 2A shows the state immediately before the pre-injection movement process is carried out. As shown in Figure 2A, the pre-injection movement process first involves moving the casting mold 31, which is placed on the horizontal moving device 51, by the moving device 50, so that the injection channel 38 is positioned below the nozzle 41 of the dispenser 40. In this arrangement, any of the three injection channels 38 may be positioned below the nozzle 41, but in this embodiment, the injection channel 38 that communicates with the spacer cone forming section 35 where the R-phase central conductor 11 is placed is positioned below the nozzle 41.

[0041] During the movement of the casting mold 31 in the pre-injection transfer process, the nozzle 41 is considered to be in a stationary position. More specifically, the nozzle 41 is positioned in a stationary position with an inclination in the vertical direction so that it is at the same angle as the inclination angle θ of the injection channel 38 located below the nozzle 41 (the same as the inclination angle θ of the cone shape of the spacer cone forming section 35). As a result, the injection channel 38 and the portion of the spacer cone forming section 35 that communicates with the injection channel 38 are positioned on the same line as the nozzle 41, parallel to the inclination angle θ of the spacer cone forming section 35.

[0042] As shown in Figure 2A, the casting mold 31 is positioned, and then, as shown in Figure 4, the casting mold 31 is moved while maintaining the nozzle 41 in a stationary state, thereby inserting the nozzle 41 into the injection channel 38 and the spacer cone forming section 35. This movement of the casting mold 31 is performed simultaneously by the horizontal movement device 51 of the moving device 50 to the right in Figure 4 and by the vertical movement device 52 to the upward. At this time, the movement of the horizontal movement device 51 and the vertical movement device 52 is controlled by the control device, so that the direction of movement of the casting mold 31 is set to be parallel to the inclination angle θ. Therefore, during the movement of the casting mold 31 in the pre-injection moving process, a gap can be maintained between the nozzle 41 and the inner circumferential surface of the injection channel 38 and the forming surface of the spacer cone forming section 35, and they can be kept non-contact.

[0043] Furthermore, during the pre-injection movement process, the movement of the horizontal movement device 51 and the vertical movement device 52 is controlled to set the vertical position of the nozzle tip 41 according to the formation position of the first resin layer 21 (see Figure 5) to be laminated.

[0044] After the pre-injection transfer process, the injection process is carried out as shown in Figure 5. In the injection process, the main agent and hardener supplied from each pipe 43 to 45 are mixed in the mixer 42 by the dispenser 40 to form a resin material, which is then supplied to the nozzle 41. The resin material is then discharged from the nozzle 41, and enough resin material is injected to form the first resin layer 21, which is laminated inside the spacer cone forming section 35 where the R-phase central conductor 11 is located, to achieve the required thickness.

[0045] After the injection process, a post-injection movement process is performed, as shown in Figure 6. In the post-injection movement process, the casting mold 31 is moved in the opposite direction to the pre-injection movement process, while maintaining the nozzle 41 in a stationary state, similar to the pre-injection movement process. This causes the nozzle 41 to be withdrawn from the spacer cone forming section 35 and the injection channel 38.

[0046] The casting mold 31 is moved simultaneously by the horizontal movement device 51 of the moving device 50 to the left in Figure 6, and by the vertical movement device 52 to the downward. At this time, by controlling the movement of the horizontal movement device 51 and the vertical movement device 52 with a control device, the direction of movement of the casting mold 31 is set to be parallel to the inclination angle θ. Therefore, even during the movement of the casting mold 31 in the post-injection moving process, a gap can be maintained between the nozzle 41 and the inner circumferential surface of the injection channel 38 and the forming surface of the spacer cone forming portion 35, and they can be kept in contact.

[0047] After the injection and transfer process, a rotational transfer process is performed as shown in Figure 7. In the rotational transfer process, the casting mold 31 is rotated 120° in a rotational direction about the central axis C2 (see Figure 2B) by the drive of the rotational transfer device 53 of the transfer device 50. This rotation causes the injection channel 38 of the spacer cone forming section 35 where the R-phase central conductor 11 is located to be moved away from below the nozzle 41, and the other injection channel 38 to be positioned below the nozzle 41. In Figure 7, the injection channel 38 of the spacer cone forming section 35 where the T-phase central conductor 11 is located is positioned below the nozzle 41.

[0048] In the lamination process, the pre-injection movement process, injection process, post-injection movement process, and rotational movement process described above constitute one cycle, and the first resin layer 21 is laminated onto the spacer cone forming section 35 where the R-phase central conductor 11 is located. Therefore, in the next cycle, the pre-injection movement process is performed to laminate the first resin layer 21 onto the spacer cone forming section 35 where the T-phase central conductor 11 is located. In other words, the rotational movement process is performed after the post-injection movement process and before the pre-injection movement process in the next cycle.

[0049] In the lamination process, after performing a cycle in which the first resin layer 21 is laminated into the spacer cone forming section 35 where the T-phase central conductor 11 is located, a cycle is performed in which the first resin layer 21 is laminated into the spacer cone forming section 35 where the S-phase central conductor 11 is located. Once the first resin layer 21 has been laminated into all the spacer cone forming sections 35 in the casting mold 31, as shown in Figure 8, the injection channel 38 of the spacer cone forming section 35 where the R-phase central conductor 11 is located is repositioned below the nozzle 41.

[0050] By repeatedly performing the cycle described above from the state shown in Figure 8, the second resin layer 22 to the fifth resin layer 25 are sequentially laminated on the first resin layer 21, resulting in the state shown in Figure 9, and the lamination process is completed. Here, the first to fourth resin layers 21 to 24 are formed independently for each spacer cone portion 12, but the fifth resin layer 25, which is the last resin layer, is formed integrally including the base portion 13. Therefore, for the fifth resin layer 25, the cycle described above may be performed three times for each phase to perform the lamination, or the amount of resin material injected may be increased for a single cycle.

[0051] After the lamination process, a curing process is carried out as shown in Figure 10. Figure 10 is an explanatory diagram of the curing process. In the curing process, the casting mold 31, which has completed the lamination process as shown in Figure 9, is placed in a constant temperature bath at a predetermined temperature and heated for a predetermined time, thereby performing primary curing of each laminated resin layer 21 to 25. After curing for the predetermined time, the casting mold 31 is demolded as shown in Figure 10, and the insulating spacer 10 is formed. After that, it is placed again in a constant temperature bath at a predetermined temperature for secondary curing, and after being heated to a predetermined temperature, it is removed and slowly cooled to complete the insulating spacer 10.

[0052] Here, the resin used in the molding method of this embodiment may be an insulating resin having a relative permittivity of 2 to 40 and being fluid under injection conditions, which can be heat-cured and function as an insulating spacer 10. 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.

[0053] The thermosetting resin is preferably an epoxy resin. The epoxy resin preferably comprises an epoxy resin main component, a curing agent, and optionally a curing accelerator. As the epoxy resin main component, an aliphatic epoxy, a alicyclic epoxy, or a mixture thereof can be used. Examples of aliphatic epoxy resins 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 with three or more functions. These can be used alone or in mixtures of two or more types. Examples of alicyclic epoxy resins include, but are not limited to, monofunctional epoxy, bifunctional epoxy, and polyfunctional epoxy with three or more functions. Alicyclic epoxy resins can also be used alone or in mixtures of two or more different alicyclic epoxy resins.

[0054] The curing agent for the thermosetting resin is not particularly limited as long as it can react with the epoxy resin main component and cure, but it is preferable to use an acid anhydride-based curing agent. Examples of acid anhydride-based curing agents include aromatic acid anhydrides, specifically phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, etc. Alternatively, cyclic aliphatic acid anhydrides, specifically tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, etc., or aliphatic acid anhydrides, specifically succinic anhydride, polyadipic anhydride, polysebacic anhydride, polyazelaic anhydride, etc., can be used, but are not particularly limited. Furthermore, as a curing accelerator, imidazole or its derivatives, tertiary amines, boric acid esters, Lewis acids, organometallic compounds, organic acid metal salts, etc., can be used as appropriate, but are not particularly limited.

[0055] The filler is included in the resin in a composition and quantity that brings the relative permittivity of the resin to the desired relative permittivity. Insulating inorganic fillers can be used as fillers. For preparing resins with relatively low dielectric constants, alumina, silica, dolomite, etc., with a relative permittivity of less than 10 can be used as fillers, while for preparing resins with relatively high dielectric constants, titanium oxide, barium titanate, strontium titanate, etc., can be used as fillers; however, the fillers are not limited to these.

[0056] In this embodiment, the composition of the injected resin can be appropriately determined by a person skilled in the art to achieve the desired physical properties such as dielectric constant and heat resistance, using thermosetting resin main components, curing agents, optionally curing accelerators, and inorganic fillers. The desired 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. Furthermore, it is preferable to design the difference in dielectric constant between adjacent resins that are laminated and in contact within the mold to be less than 1. If the difference in dielectric constant between adjacent resins is too large, problems such as electric field concentration on the surface of a spacer at the interface may occur.

[0057] In the molding method of this embodiment, two or more resins with different dielectric constants are used, preferably three or more types of resins. Therefore, there may be four to ten or more types. That is, the dielectric constants of the injected resins differ by at least two stages, and may differ by three to ten or more stages. These two or more different resins can be prepared to a desired composition in a resin preparation unit (not shown) connected to the dispenser 40. Then, a control device (not shown) sends a predetermined amount of resin of a predetermined composition to the dispenser 40 so that it can be injected into the casting mold 31. In one embodiment, the injection order of the two or more resins with different dielectric constants may be in descending order of dielectric constant. Alternatively, the injection order may be in descending order of dielectric constant, or in an order in which the dielectric constant changes from high to low to medium, and is not particularly limited. The present invention is not limited to any particular embodiment regarding the injection order of two or more resins with different dielectric constants.

[0058] Each step of the molding method in this embodiment is performed in a tank where the temperature and vacuum can be controlled, and the pressure is preferably around 10 Torr (1.3 kPa) or less. Furthermore, the pressure during casting is preferably between 10 Torr (1.3 kPa) and 30 Torr (3.9 kPa) or less, and this pressure is preferably maintained for about 1 to 3 minutes. By maintaining this pressure range, air bubbles can be eliminated.

[0059] As described above, according to the first embodiment, since the injection process is repeated to laminate each resin layer 21 to 25, the constraint of obtaining a string-shaped extruded product as in the conventional method during molding can be alleviated, and the process of injecting the resin material into the casting mold 31 can be simplified. In addition, since a cone-shaped insulating spacer 10 with a progressively changing dielectric constant can be molded, the insulating spacer 10 can be miniaturized, and the electric field component in the creepage direction at the spacer cone portion 12 can be reduced.

[0060] Furthermore, according to the first embodiment, in the pre-injection movement step and the post-injection movement step, the casting mold 31 can be moved while the dispenser 40 including the nozzle 41 is stopped, thereby moving the nozzle 41 in and out of the cavity 33. This eliminates, for example, the equipment burden for moving the nozzle 41 in the direction of rotation with respect to the orthogonal three axes and each axis, as well as the preparatory burden of making each pipe 43-45 long and flexible or performing complex installation work to allow such movement.

[0061] Furthermore, in the first embodiment, the nozzle 41 can maintain non-contact with the inner circumferential surface of the injection channel 38 and the forming surface of the spacer cone forming portion 35 during the movement of the casting mold 31 in the pre-injection and post-injection movement processes. This prevents the nozzle 41 from contacting or rubbing against the spacer cone forming portion 35, etc., when the nozzle 41 is moved in and out of the cavity 33, thereby maintaining a good appearance of the molded insulating spacer 10 and enabling stable quality evaluation.

[0062] [Second Embodiment] Next, a second embodiment 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 first embodiment, and their descriptions may be omitted or simplified.

[0063] A second embodiment of the present invention will be described with reference to Figures 11 to 18. Figure 11 is an explanatory diagram of the preparation process. Figure 12 is an explanatory diagram of the mold placement process and the pre-injection movement process. Figure 13 is an explanatory diagram of the pre-injection movement process and the injection process. Figure 14 is an explanatory diagram of the post-injection movement process. Figure 15 is an explanatory diagram of the rotational movement process. Figures 16 and 17 are explanatory diagrams showing the state at an intermediate stage of the lamination process. Figure 18 is an explanatory diagram showing the state after the completion of the lamination process. In the second embodiment, compared to the first embodiment, the orientation of the nozzle 41 and the injection channel 38 (see Figures 12 and 17) and the attachment and detachment of the upper mold 34 of the casting mold 31 (see Figures 11 and 16) are mainly changed.

[0064] As shown in Figure 11, in the second embodiment, the preparation step differs from the preparation step of the first embodiment in that the upper mold 34 is not placed on the lower mold 32, and the upper mold 34 is removed from the lower mold 32, leaving the upper part of the cavity 33 open.

[0065] As shown in Figure 12, in the second embodiment as well, after the preparation step, a mold placement step is performed in which the casting mold 31 is placed on the horizontal moving device 51 of the moving device 50, and then the lamination step is carried out. In the lamination step in the second embodiment as well, the pre-injection moving step, injection step, post-injection moving step and rotational moving step constitute one cycle, and multiple resin layers (five layers in this embodiment) are laminated by repeating this cycle multiple times.

[0066] As shown in Figure 12, in the pre-injection movement step in the second embodiment, the nozzle 41 is stopped in a position parallel to the vertical direction. In this embodiment, the casting mold 31 is moved by the horizontal movement device 51 so that the spacer cone forming portion 35, where the R-phase central conductor 11 is located, is positioned below the nozzle 41.

[0067] Subsequently, as shown in Figure 13, while maintaining the stopped state of the nozzle 41, the casting mold 31 is moved upward by the vertical movement device 52, and the nozzle 41 is inserted into the spacer cone forming section 35. During the movement of the casting mold 31 in the pre-injection movement process, a gap is maintained between the nozzle 41 and the forming surface of the spacer cone forming section 35, allowing them to remain non-contact. After the pre-injection movement process is completed, resin material is discharged from the nozzle 41 in the injection process, and resin material equivalent to the required thickness of the first resin layer 21 to be laminated inside the spacer cone forming section 35 is injected.

[0068] As shown in Figure 14, in the post-injection transfer step in the second embodiment, the casting mold 31 is moved downward by the vertical transfer device 52, and the nozzle 41 is withdrawn from inside the spacer cone forming section 35. Even while the casting mold 31 is moving during the post-injection transfer step, a gap is maintained between the nozzle 41 and the forming surface of the spacer cone forming section 35, allowing them to remain in contact.

[0069] As shown in Figure 15, the casting mold 31 is rotated by the drive of the rotary moving device 53 in the rotational moving process, and the spacer cone forming section 35 where the central conductor 11 of the T phase is placed is positioned below the nozzle 41. In each of the above steps, one cycle of the lamination process is completed, and the same cycle is repeated in the lamination process, and after a predetermined number of times for lamination from the first resin layer 21 to the fourth resin layer 24, the state shown in Figure 16 is reached.

[0070] In the lamination process, the pre-injection transfer process for laminating the fifth resin layer 25, which will be the final resin layer, is temporarily put on hold in the state shown in Figure 16, and the upper mold 34 is attached to the lower mold 32, closing the casting mold 31. The attachment of the upper mold 34 is preferably carried out in a tank (not shown) where the temperature and vacuum level can be controlled. In this case, the upper mold 34 is set in the tank beforehand, and the upper mold 34 is attached to the lower mold 32 under reduced pressure using a lifting device (not shown) that raises and lowers the upper mold 34. However, this attachment can also be carried out with the reduced pressure released or outside the tank.

[0071] In the casting mold 31 used in the second embodiment, the injection channel 61 extends parallel to the vertical direction. The injection channel 61 is formed in three locations (two locations shown in Figure 16, one location omitted), and is formed to connect to the upper end of each of the three spacer cone forming sections 35.

[0072] When the casting mold 31 is closed, the casting mold 31 is positioned so that the injection channel 61 is located below the nozzle 41, as shown in Figure 17. Subsequently, the above-described cycle is performed once or three times depending on the phase, so that the fifth resin layer 25, which is the final resin layer, is laminated, as shown in Figure 18. After the lamination process, a curing process is performed in the same manner as in the first embodiment, and the insulating spacer 10 is formed.

[0073] The second embodiment also provides the same effects and benefits as the first embodiment. Furthermore, since the first to fourth resin layers 21 to 24 are laminated with the upper mold 34 removed during the lamination process, the positional accuracy of inserting and removing the nozzle 41 into the cavity 33 is reduced, thereby facilitating molding and further stabilizing quality.

[0074] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented with various modifications. In the embodiments described above, the size, shape, orientation, etc., shown in the accompanying drawings are not limited thereto, and can be appropriately modified within the scope that allows the present invention to exert its effects. In addition, the present invention can be implemented with appropriate modifications as long as it does not deviate from the scope of its objectives.

[0075] In the above embodiments, the insulating spacer 10 is configured as a three-phase integrated type, but the configurations of the above embodiments can also be applied to single-phase insulating spacers. In the single-phase insulating spacer, the central conductor 11 is changed to one.

[0076] Furthermore, in the three-phase integrated insulating spacer 10 of the above embodiments, the layout of the three central conductors 11 and the three spacer cone portions 12 surrounding them may be changed. For example, instead of arranging them at equal angles around the central axis C2 (see Figure 2B), the central conductors 11 and spacer cone portions 12 may be arranged at different angles depending on the arrangement angle of the conductors in the gas-insulated switchgear, for example, at 90°, 90°, and 180° angle intervals. Also, the insulating spacer 70 may have the modified configuration shown in Figure 19A. Figure 19A is a view of the insulating spacer according to the modified configuration from below. Note that in Figure 19A, the first to fifth resin layers 21 to 25 (see Figure 1A) are not shown. As shown in Figure 19A, in the modified insulating spacer 70, the three central conductors 11 and the three spacer cone portions 12 surrounding them are arranged at predetermined intervals in the linear direction (left-right direction in Figure 19).

[0077] The insulating spacer 70 is formed using a casting mold 75 shown in Figure 19B. Figure 19B is a view from above of a casting mold according to a modified example. As shown in Figure 19B, the casting mold 75 of the modified example has a cavity 33 with three spacer cone forming sections 35 arranged horizontally, corresponding to the three spacer cone sections 12 in the insulating spacer 70. The injection channel 38 is formed to communicate with the right side of each of the three spacer cone forming sections 35 in Figure 20, in other words, one end in the direction of alignment.

[0078] In the modified molding using the casting mold 75, a horizontal movement process is performed instead of the rotational movement process in the first embodiment. In the horizontal movement process, the casting mold 31 is moved in the left-right direction in Figure 20 (the direction in which the three spacer cone forming sections 35 are aligned) by the driving of the horizontal movement device 51 of the moving device 50, and each injection channel 38 is positioned below the nozzle 41. According to the modified version, it is possible to position the injection channels 38 communicating with the three spacer cone forming sections 35 below the nozzle 41 without rotating the casting mold 31 with the rotational movement device 53.

[0079] Furthermore, although the case in which the dispenser 40 is fixedly positioned above the casting mold 31 has been described, it is not limited to this. For example, the dispenser 40 may be movable in a horizontal direction and in a direction intersecting the direction of movement of the horizontal moving device 51 by a uniaxial motion mechanism or the like, but considering the burden on equipment and preparation work, it is more advantageous to fixate the dispenser 40 in place.

[0080] Furthermore, in the lamination process of each of the above embodiments, the nozzle 41 was extended and retracted each time a resin layer was laminated in the spacer cone forming section 35, and a cycle of laminating the resin layer of another spacer cone forming section 35 was performed, but this is not limited to this. For example, in the injection process of each cycle of the lamination process, multiple resin layers (for example, the first to fourth resin layers 21 to 24) may be laminated continuously in one spacer cone forming section 35.

[0081] Furthermore, the number of resin layers laminated in the insulating spacer 10 is not limited to the five layers in each of the above embodiments, but may be increased or decreased as appropriate.

[0082] This application is based on Japanese Patent Application No. 2023-029395, filed on February 28, 2023. All of its contents are included here. [Explanation of Symbols]

[0083] 10: Insulating spacer 11: Central conductor 12: Spacer cone section 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: Casting mold 32: Lower mold 33: Cavity 34: Upper mold 35: Spacer cone forming section 41: Nozzle 70: Insulating Spacer 75: Casting mold C1: Center axis (center position) C2: Central axis θ: Tilt angle

Claims

1. A method for forming an insulating spacer, comprising a central conductor and at least one cone-shaped spacer cone portion provided around the central conductor, Using a casting mold having a lower mold and an upper mold that form a cavity of a shape corresponding to the insulating spacer, and a nozzle for injecting resin material into the cavity, A mold placement step involves positioning the casting mold with the cone-shaped top-forming portion of the cavity facing downwards, A lamination process involves repeatedly performing a pre-injection transfer process, an injection process, and a post-injection transfer process to laminate multiple resin layers, The process includes a curing step in which the resin layers laminated in the lamination step harden and the insulating spacer is released from the casting mold, The pre-injection movement step involves moving the casting mold while the nozzle is stopped, thereby inserting the nozzle into the cavity. The injection step involves injecting the resin material from the nozzle into the cavity, The method for molding an insulating spacer is characterized in that the post-injection movement step involves moving the casting mold while the nozzle is stopped, thereby removing the nozzle from inside the cavity.

2. The method for molding an insulating spacer according to claim 1, characterized in that the pre-injection movement step and the post-injection movement step are performed by stopping the nozzle in a position inclined according to the inclination angle of the cone shape, and the direction of movement of the casting mold is set to be parallel to the inclination angle.

3. In the mold placement step described above, the upper mold is removed from the lower mold. The method for molding an insulating spacer according to claim 1, characterized in that the upper mold is attached to the lower mold before the pre-injection transfer step in which the final resin layer in the lamination step is laminated.

4. The insulating spacer is provided with multiple spacer cone portions arranged at equal angles around a predetermined central position. The casting mold is provided with a cavity containing a plurality of spacer cone forming portions arranged around a central axis, which extend vertically in accordance with the plurality of spacer cone portions, The method for molding an insulating spacer according to any one of claims 1 to 3, characterized in that the lamination step further comprises a rotational movement step of moving the casting mold in a rotational direction about the central axis after performing the post-injection movement step and before performing the pre-injection movement step of laminating the next resin layer.

5. The insulating spacer is provided with multiple spacer cone portions arranged in a linear direction. The casting mold is provided with a plurality of spacer cone forming sections arranged horizontally in the cavity, corresponding to the plurality of spacer cone sections. The method for molding an insulating spacer according to claim 1, characterized in that the lamination step further comprises a horizontal movement step of moving the casting mold in the direction in which the plurality of spacer cone forming portions are aligned, after performing the post-injection movement step and before performing the pre-injection movement step of laminating the next resin layer.

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