JP2851112B2 - Manufacturing method of casting insulator and casting mold for casting insulator used in the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a method for manufacturing a cast insulator suitable for a cast insulator used at a high voltage and a large current and a note used for the same. Mold related to mold.

(Prior art) In general, cast products made of epoxy resin can provide excellent electrical insulation as well as mechanical stability, and can obtain the same quality of mechanical characteristics. It has been widely used in transformers and small electric motors. Various advantages are being studied for large-sized equipment because these advantages can be fully utilized.

With the recent mass production of cast products using epoxy resin,
Casting articles are often produced by the gelling method under pressure. This pressurized gelation method involves the steps of:
The temperature is set higher than the temperature of the resin to be injected, and a certain temperature gradient is applied to the mold. Thereafter, the casting resin is injected from the bottom of the casting mold or from below. Thereafter, after the casting resin is completely filled, the casting resin is quickly cured at a high temperature while applying a constant pressure. The feature of this method is that the casting resin is injected from the bottom or the bottom of the casting mold, and the casting resin that enters the casting mold is gently filled into the casting mold without causing turbulence. .

In this case, since the casting resin does not cause turbulence, the temperature of the previously injected casting resin is higher than the temperature of the later injected casting resin due to the heat conduction of the temperature of the main mold,
A temperature gradient is applied to the casting resin filled in the casting mold.

Furthermore, a constant temperature gradient is also applied to the casting mold, and the top of the casting mold farthest from the inlet and outlet for casting resin has the highest temperature, and the temperature near the injection port is the lowest, so the injection port The temperature of the casting resin at the farthest point is the highest, the temperature of the casting resin near the injection port is the lowest, and the temperature of the casting resin filled in the casting mold is definitely increased. Therefore, curing starts from the casting resin farthest from the injection port, and the casting resin closer to the injection port cures more slowly. In addition, when the casting resin is cured, curing shrinkage occurs.However, since the casting resin is pressurized at a constant pressure from the injection port, a portion shrunk by the curing is closer to the injection port that has not been cured yet. Supplemented with casting resin. By applying such a pressure gelation method, the casting resin can be quickly cured, internal strain due to shrinkage is reduced, and a cast product having excellent characteristics without sink marks can be manufactured.

As an example to which this pressure gelation method is applied, there is a propulsion coil 52 for a magnetically levitated railway as a cast insulator 51 as shown in FIG.

This is, for example, about 650 mm x 1600 mm
Wound coil conductor 54 in the shape of a race track
Is covered with a casting resin 58. The problem here is that, in the manufacture of a large cast insulator 51 such as a magnetically levitated rail propulsion coil 52, how the coil conductor 54 is embedded in the center of the cast resin 58, Whether the coil conductor 54 is fixed and set in the casting mold.

Conventionally, in order to solve this problem, as shown in FIG. 6, an insulating space 101 is arranged between the coil conductor 54 and the casting mold 102 at a predetermined interval over substantially the entire length of the coil conductor 54. , The coil conductor 54 was set.

However, in this case, the insulating spacer 101 is
It was manufactured with the same composition as that described above, the thickness was processed and adjusted according to the distance between each coil conductor 54 and the mold 102, and the surface was roughened by sandblasting to be degreased before use.

Then, a casting resin 58 is injected into this, and the insulating spacer 10 is formed.
The casting insulator 51 was manufactured by curing all of them.

(Problems to be Solved by the Invention) As described above, the casting object is supported by using the insulating spacer, the casting resin is injected, and the pressure gelation method is applied, and the insulating spacer is hardened together with the insulating spacer. However, the adhesiveness between the casting resin and the insulating spacer is not always good. Therefore, peeling may occur at the interface between the casting resin and the insulating spacer due to residual stress due to the curing reaction of the casting resin and expansion and contraction due to temperature change. When peeling occurs, stress concentrates on the peeled portion, and cracks occur in the casting resin. Further, even if cracks do not occur, corona is generated from the place where they are peeled off, the electrical characteristics are degraded, and a short circuit accident is caused.

Also, in terms of cost, the production of the insulating spacer and the assembly in the casting mold require a lot of man-hours, which is disadvantageous in that the cost is increased.

The present invention has been made in order to eliminate the above-described disadvantages, and does not use a complicated insulating spacer having a dimensional shape, and furthermore, a method of manufacturing a cast insulator without occurrence of a crack or a short circuit accident and the like. An object of the present invention is to provide a casting mold for a casting insulator used for this.

[Constitution of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that the casting insulator of claim (1) is furthest from the injection port of the filling cavity of the casting mold. The casting object is accommodated and supported in the filling space by the support placed away from the vicinity of the upper part, and thereafter, the temperature gradient is set in the casting mold so that the temperature decreases from the vicinity of the upper part to the vicinity of the injection port. Thereafter, the heated casting resin is injected and filled from the casting mold inlet, and thereafter, the temperature of the casting resin in the vicinity of the upper portion is locally increased and hardened, thereby supporting the casting object. And at the same time, maintain the other casting resin around the support in an uncured softened state.After that, the support is retracted from the filling space, and the resulting space is filled with the casting resin by pressurization. Thereafter, the entire casting resin is cured. You.

A method of manufacturing a cast insulator according to claim (2) is characterized in that, in the method of manufacturing a cast insulator according to claim (1), the object to be cast is a conductor or a coil conductor. It is.

The casting mold for a casting insulator according to claim (3) is a mold body having a filling space for accommodating a body to be cast and an inlet for injecting a casting resin into the cavity. It consists of a local heater and a heater that heats the upper part, which is provided in the mold body, and heats the upper part farthest from the inlet of the filling cavity, and the temperature decreases from the upper part to the inlet. A temperature gradient is set, and the upper part of the casting resin injected against the gradient is locally heated to a higher temperature than other parts by the above-mentioned local heating body and cured, and then the other casting resin is cured by the heating body. Heating means for heating to a temperature, and a plurality of supports provided so as to be able to protrude and retract into the filling space and arranged so as to avoid the vicinity of the upper portion of the filling space, and projecting the object to be cast into the filling space by projection Retreats after the upper part is hardened And a supporting means.

Furthermore, in the casting mold for a casting insulator according to claim (4), in the casting mold for a casting insulator according to claim (3), the heating means is an electric heater, and the filling space is not filled. A heat retaining groove for preventing heat conduction is provided between an electric heater that heats the vicinity of the upper portion most distant from the injection port and another electric heater.

(Function) In the method for manufacturing a cast insulator according to claims (1) and (2), the vicinity of the uppermost portion farthest from the injection port of the filling space (substantially the same as the object to be cast), that is, pressurization. In the gelation method, the part where the temperature of the casting resin rises the most is hardened before the other parts by local heating and heating, thereby supporting the cast body, so that the uncured softened part of the other parts Can be retracted from the casting resin and immersed outside the filling cavity.

The casting mold for a casting insulator according to claims (3) and (4) is a local heating element for locally heating the vicinity of a part farthest from the injection port of the object to be cast, and other parts. Since a heating element is provided for heating the target, setting of a temperature gradient, local hardening, and the like can be easily performed. Since the support can also be moved into and out of the cavity, it can be used for various shapes of the molded object, and can be retracted out of the filling cavity before the casting resin is cured. Therefore, it is extremely suitable for implementing the method for manufacturing a cast insulator according to claims (1) and (2).

(Embodiment) Hereinafter, the present invention will be described in detail by way of an embodiment with reference to FIGS. 1 to 5.

A first embodiment will be described with reference to FIG. 1 and FIG.

FIG. 1 is a sectional view of a casting mold 1A for a casting insulator according to the present invention. Reference numeral 1 denotes a mold body, in which a filling space (hereinafter referred to as a space) 2 is provided, and an injection port 4 for injecting a casting resin 58 is provided below. The object 53 to be charged into the cavity 2 is a conductor 55 having an outlet portion 55a, and is fixed with the bolt 5 with the outlet portion 55a facing down.

Further, a support means 11 is provided at an intermediate portion of the mold body 1, and is composed of a plurality of supports 11a, 11b,..., And these supports 11a,. It is attached to the main body 1 so as to be able to come and go in the cavity 2 by a sliding method or a screwing method. By projecting them and adjusting their positions, the conductor 55 is positioned and supported at a predetermined position and posture. For the reason described below, the upper portion 2a farthest from the injection port 4 of the cavity 2, that is, the casting resin 58 is arranged so as to avoid the portion where the temperature is highest at the time of the pressure gelation manufacturing method. Although only the supports 11a, 11b... Are shown in the left-right direction in the drawing, they are also provided in a direction perpendicular to these.

Further, a heating means 21 is provided around the cavity 2 in the mold body 1. This is composed of a local heater 22 composed of electric heaters 22a, 22a,... And a heater 23 composed of electric heaters 23a, 23a,. The body 23 is provided sparsely.
The electric heaters 22a are provided so as to surround the upper portion 2a farthest from the injection port 4 of the above-mentioned space 2, so that the temperature of the far upper portion 2a is locally higher than the temperatures of other portions. Can be set.

Although the casting mold 1A of the present embodiment has the above-described configuration,
An embodiment of the manufacturing method of the present invention using this will be described.

The temperature setting of the casting mold 1A is determined by the relationship between the temperature of the casting resin 58 used and the curing time. FIG. 2 is a diagram showing the relationship between the casting resin 58 (epoxy resin) used in the present embodiment, temperature and curing time. If the temperature is high, the casting resin 58 hardens in a short time. Heating of the casting mold 1A is done by the upper heater
By setting the temperature of 22a to 140 ° C and the temperature of the other heaters 23a to 125 ° C, the temperature of the upper part of the casting mold, that is, the upper part 2a farthest from the injection port 4 of the cavity 2 is set.
Is the same as the temperature of the heater 22a, and the other temperatures are the same as the temperature of the heater 23a.

When the temperature of the casting mold reaches a predetermined temperature distribution, the casting resin 58 is injected from the injection port 4 provided at the bottom or below the casting mold without applying a constant turbulent flow while applying a constant pressure P. I do. Since the casting resin is heated from the casting mold while being injected, a temperature gradient is generated in the casting resin up and down. After the casting resin 58 is completely filled, a constant pressure P is kept applied. Thereby, the temperature of the casting resin 58 in the vicinity of the heater 22a and the upper portion 2a of the cavity 2 becomes 140 ° C., and as shown at a point a in FIG. The temperature of the casting resin 58 in the portion surrounded by the heater 23a is 1
It will reach 20 ° C. and will not cure until 30 minutes have passed, as indicated by point b in FIG.

Therefore, the casting resin in the upper part of the conductor 55, that is, in the vicinity of the upper part 2a
When the resin 58 has hardened, the supports 11a, 11b,... Of the casting resin 58 which are still softened are retracted until their tips are flush with the inner wall of the cavity 2, that is, flush. Even if these supports 11a,... Are pulled back, the casting resin 58 in the upper vicinity 2a farthest from the injection port 4 in the cavity 2 is hardened,
Since the upper portion 55b of the conductor 55 is fixed to this, there is no inconvenience.

By pulling back the support members 11a in this manner, the portions where these are located become empty, but since a constant pressure P is applied from the injection port 4, the uncured heater 23a ... The casting resin 58 in the vicinity moves and is supplemented.

Then, the casting resin 58 near the heater 23a,.
Since the setting is performed at 30 ° C. for 30 minutes, the casting resin 58 in the vicinity of the upper portion 55b of the conductor 55 hardens 20 minutes after hardening, and the entire casting resin 58 filled in the casting mold 1A is hardened. After the entire casting resin 58 is cured, the mold is released and secondarily cured, and a casting insulator without an insulating spacer is obtained.

As in the present embodiment, in the case where the local heater and the heater are configured by changing the pitch of the electric heater, a desired temperature gradient can be easily obtained by controlling the current.

Next, a second embodiment will be described with reference to FIGS.

The cast insulator 51 of the present embodiment is the propulsion coil 52 for a magnetically levitated railway described in the conventional example, and has an outlet 54a.

FIG. 3 is a front view showing a state where the coil conductor 54 is set in the casting mold 31A of the present invention and filled with the casting resin 58, and FIG. 4 is a view along the line IV-IV in FIG. FIG.

The casting mold 31A is composed of a mold body 31 that can be divided into two parts. A cavity 33 is formed inside the casting body 31A.
Is provided.

Further, a heating means 35 is provided so as to surround the cavity 33 (not shown in FIG. 3), which is a local heating device comprising electric heaters 36a,... 36a embedded in the mold body 31. Heating body 37 consisting of body 36 and electric heaters 37a,.
And a heat retaining groove 38 composed of a groove formed at the boundary between the local heating element 36 and the heating element 37. The heat retaining groove 38 prevents the heat from the heater 36a from being transmitted to the outside and escaping. The space 33 corresponding to the portion (upper portion of the mold body 31) surrounding the heat retaining groove 38 is the upper portion 33a farthest from the injection port 34 described in the first embodiment. This is the part that is heated first and cured first.

Also, along the race track-shaped space 33, support means
41 are provided. This is a plurality of pairs of supports 41a, 41b, 41c, 41d, 41 provided opposite to each other via the space 33.
e, 41f. These are provided so as to be able to come and go with respect to the vacant space 33, and the adjustment of the protruding position is easy by screwing or sliding.

The casting mold 31A of the present embodiment is configured as described above. Next, an embodiment of the manufacturing method of the present invention will be described together with the operation.

The opening 54a of the coil conductor 54 is fixed to the bottom of the casting mold 31A with the bolt 42. However, since the position of the coil conductor 54 is not fixed and unstable even when the exposing portion 54a is fixed, the position is determined by the supports 41a,.
Fix so that it is embedded in the center of.

After the positioning is completed, when the mold body 31 is heated by the heating means 35, the temperature of the portion surrounded by the heat retaining groove 38 becomes higher than that of the other portions due to the heat retaining groove 38. That is, as in the case of the first embodiment, the temperature of the upper portion 33a farthest from the injection port 34 of the space 33 becomes higher than the other portions. For example, a temperature gradient is set such as 140 ° C. in the heat retaining groove 38 and 120 ° C. in the other portions. Then, similarly to the pressure gelation method, the casting resin 58 is used.
Is gradually injected from the injection port 34, and a constant pressure P is applied even after the space 33 is filled.

After maintaining such a state, the high-temperature portion is hardened, and when hardened, the support members 41a,..., 41f are retracted, and then the whole is hardened, as in the case of the first embodiment. Description is omitted.

The casting mold provided with the heat retaining groove as in the present embodiment prevents the heat from escaping outward, so that local heating can be performed quickly and accurately.

The object to be cast is not limited to a conductor, a coil conductor, or the like, and may be any insulator as long as it is a cast insulator.

The casting resin is not limited to the epoxy resin, but may be any other thermosetting resin.

[Effects of the Invention] As described above in detail, the method for manufacturing a cast insulator according to the present invention supports the cast body by locally curing the cast resin. Since the body is also removed before curing, occurrence of an accident such as cracking or property deterioration due to peeling is prevented. In addition, since there is no need to manufacture or attach an insulating spacer, the effect of reducing costs is achieved.

In addition, since the casting mold for the casting insulator of the other invention is configured such that the support can be freely moved in and out, the casting mold can correspond to a body to be cast having various shapes, and retreats and separates from the casting resin. Therefore, accidents due to foreign matter are prevented. Furthermore, since the heating means is constituted by the local heating element and the heating element, setting of the temperature gradient of the casting mold, local hardening, and the like can be easily performed. Furthermore, since the heater provided with the heat retaining groove can accurately perform local heating, the quality is improved and the workability is good.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a main part of a first embodiment of a casting mold for a casting insulator according to the present invention. 2 is a characteristic curve diagram of the casting resin used in each embodiment, FIG. 3 is a front view of the embodiment of FIG. 2, and FIG. 4 is a view along the line IV-IV of FIG. FIG. 5 is a front view of the cast insulator used in the description of the second embodiment and the conventional example, and FIG. 6 is an explanatory view of the conventional example. 1, 31 mold main body 1A, 31A casting mold 2, 33 filling space 2a, 33a near the top of filling space 4, 34 injection port 11, 41 support means 11a, 11b Supports 41a to 41f Supports 21, 35 Heating means 22, 36 ... Local heating bodies 22a, 36a ... Electric heaters 23, 37 ... Heating bodies 23a, 37a ... Electric heaters 38 ... heat retention groove 53 ... cast object 54 ... coil conductor 55 ... conductor 58 ... cast resin

Continuation of the front page (72) Inventor Teruhiko Maeda 1 Toshiba-cho, Fuchu-shi, Tokyo In the Toshiba Fuchu factory (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 39/00-39/44 B29C 33/00-33/76

Claims (4)

(57) [Claims] An object to be cast is accommodated and supported in a filling cavity by a support disposed so as to avoid an upper portion farthest from an injection port of a filling cavity of a casting mold. A temperature gradient in which the temperature decreases toward the vicinity of the injection port is set in the casting mold, and then, the heated casting resin is injected and filled from the injection port of the casting mold. The temperature of the mold resin is locally increased and hardened, thereby supporting the object to be cast and maintaining the other cast resin around the support in an uncured and softened state. A method for manufacturing a cast insulator, comprising: retreating from a place, filling a space created by the cast resin with pressurization, and thereafter curing the entire cast resin. 2. The method according to claim 1, wherein the object to be cast is a conductor or a coil conductor. 3. A mold body having a filling space for accommodating a casting object and an injection port for injecting a casting resin into the filling body, It consists of a local heating body that heats the vicinity of the far upper part and a heating body that heats other parts, and sets a temperature gradient where the temperature decreases from the vicinity of the upper part to the vicinity of the injection port. Heating means for locally heating the upper part of the mold resin to a higher temperature than other parts by the local heating body and hardening it, and then heating the other casting resin to the curing temperature by the heating body; A support that is freely provided and is disposed so as to avoid the vicinity of the upper part of the filling space, and that supports the object to be cast in the filling space by protruding, and that the vicinity of the upper part hardens and then retreats and retracts. Means. Casting mold for casting insulating material and. 4. A heating device according to claim 3, wherein the heating element and the local heating element are electric heaters, and a heat retaining groove for preventing heat conduction is provided between the heating element and the local heating element.
The casting mold for the described casting insulator.