JPH08115837A - Manufacture of resin-molded split current transformer - Google Patents

Abstract

PURPOSE: To manufacture a resin-molded split current transformer without using a plurality of insulating spacers and without performing an operation by which a material whose quality is identical to that of a synthetic resin for molding is poured into a gap part from which a screw-type push pin has been pulled out. CONSTITUTION: A recessed part 11c and a screw-type push pin 6 are installed at a metal mold 1c for molding. A current-transformer element in which a secondary coil 3 has been wound on a semi-ringed core 2 is housed in a prescribed position inside metal molds 1a, 1c for molding, the screw-type push pin 6 is screwed, and the current-transformer element is fixed via an insulating spacer 15. A synthetic resin 4 is poured into the metal molds 1a, 1c for molding, it is hardened, the metal molds 1a, 1c for molding are released, and protruding parts on a molded covering layer including the insulating spacer 5 are removed. A magnet is mounted on, and attached to, the metal molds for molding, the core for the current-transformer element is attracted by the magnet, and the current-transformer element may be fixed inside the metal molds for molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a resin mold split type current transformer in which a current transformer element having a secondary coil wound around a semi-annular iron core is covered with a synthetic resin.

[0002]

2. Description of the Related Art A split type current transformer applied to a power cable or the like is generally made by dividing an annular iron core into two, and forming a current transformer element in which a secondary coil is wound around each semi-annular iron core. The resin-molded split type current transformer is covered with a mold to form a combination of them. This split-type current transformer is a resin-mold split-type current transformer assembled by sandwiching the primary conductor from both sides, and then joining and joining the iron core split surfaces, which is easy to install and has a feature that it can be constructed in a small size. are doing.

A conventional method for manufacturing a resin mold split type current transformer will be described below with reference to FIG. In FIG. 3, a secondary coil 3 is wound around a semi-annular iron core 2 to form a current transformer element. This current transformer element is housed and fixed in a predetermined position of the mold dies 1a and 1b divided into two. in this case,
The current transformer element is set on the molding die 1a in a predetermined position in the molding dies 1a and 1b with the divided surface of the iron core 2 of the current transformer element being in contact with the molding die 1a.
Further, at a predetermined position on the outer circumferential surface of the coil 3 in advance, with a material smaller than the distance between the outer circumferential surface of the coil 3 and the inner side surface of the molding die 1b and made of the same material as the synthetic resin for molding. The semi-cured insulating spacer 5 is attached and fixed with an adhesive. Next, the molding dies 1a and 1b are assembled by tightening with tightening bolts (not shown). After that, the screw type push pin 6 mounted in the molding die 1b so as to be able to move in and out of the molding die 1b is screwed in until the tip portion contacts the insulating spacer 5. As a result, the current transformer element including the iron core 2 and the coil 3 wound around the iron core 2 is in a state of being housed and fixed in the molding dies 1 a and 1 b via the insulating spacer 5.

After completion of the above-mentioned assembly process, the synthetic resin 4 is injected from a casting port (not shown) of the molding dies 1a and 1b and left for a certain period of time. The mold push pin 6 is pulled out, and the molding dies 1a and 1b are removed to release the mold. After that, a material of the same quality as the synthetic resin for molding is poured into the void portion of the removed screw type push pin 6 and left in this state for a predetermined time to completely cure the synthetic resin to obtain a resin mold split type current transformer. A split type current transformer is configured by combining two resin mold split type current transformers so that the split surfaces of the iron core 2 are in contact with each other.

[0005]

In the above-mentioned conventional manufacturing method, when the synthetic resin 4 is injected and the latter half is in the cured state, the screw type push pin 6 is pulled out and the molding die 1 is molded.
After releasing a and 1b, a work of pouring a material of the same quality as the synthetic resin for molding into the void portion of the extraction trace of the screw type push pin 6 is performed. At this time, regarding the void portion,
In order to improve the adhesive airtightness between the semi-cured synthetic resin and the pouring material, it is necessary to perform surface roughening with a cutting jig such as a knife. Immediately after releasing the molding dies 1a and 1b. There was a drawback that it was not possible to shift to the curing process. Further, it is necessary to prepare a small amount of pouring material in advance, which has a drawback of increasing the number of processing steps.

There is also a method of fixing the current transformer element in the molding die through a plurality of insulating spacers, but it takes a lot of time to position the current transformer element through the plurality of insulating spacers. There was a drawback that required.

The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to use a synthetic resin for molding without using a plurality of insulating spacers and at the time of releasing the mold for molding after injection of the synthetic resin. An object of the present invention is to provide an economical method for manufacturing a resin mold split type current transformer that improves workability and does not perform the work of pouring the same material.

[0008]

In order to achieve the above object, the invention according to claim 1 provides a current transformer element having a secondary coil wound around a semi-annular iron core in a mold for molding. In a method of manufacturing a resin mold split type current transformer in which a current transformer element other than the iron core split surface is mold-coated with a synthetic resin, the mold for molding is located radially outside the current transformer element. A recess is provided on the inside, and a screw type push pin that moves the molding die in and out is provided at the position of this recess, and an insulating spacer made of the same material as the mold resin is provided in the recess to insulate by the screw type push pin. The current transformer element is stored and fixed in a predetermined position of the molding die via the spacer, and then the synthetic resin is injected into the molding die to be cured, and then the molding die is released, and after that Insulation spacer And removing the protruding portion of the mold coating layer comprising.

According to a second aspect of the present invention, a current transformer element in which a secondary coil is wound around a semi-annular iron core is housed and fixed at a predetermined position in a molding die to remove the iron core dividing surface. In a method for manufacturing a resin mold split type current transformer in which a transformer element is mold-coated with a synthetic resin, a magnet is attached to a predetermined position of a molding die, and the magnet attracts an iron core of the current transformer element. It is characterized in that the element is housed and fixed in a predetermined position in the molding die, and then a synthetic resin is injected into the molding die to be cured and then the molding die is released.

[0010]

According to the invention described in claim 1, a screw type push pin is provided in the recess of the molding die, and the current transformer element is provided in the molding die through an insulating spacer located in the recess. Since it is stored and fixed at a predetermined position, when the synthetic resin injected into the molding die is in a semi-cured state or a cured state, it is formed as a protruding portion in the mold coating layer. Therefore, when the synthetic resin for molding becomes semi-cured, it is not necessary to release the screw type push pin and to pour the material of the same quality as the synthetic resin for molding into the gap.

According to the second aspect of the present invention, since the current transformer element is housed and fixed in a predetermined position of the molding die by the magnet, there is no need to provide a screw type push pin in the molding die, and therefore, It is not necessary to remove the screw type push pin and pour a material of the same quality as the synthetic resin for molding into the void portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a resin mold split type current transformer of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention described in claim 1. In FIG. 1, a secondary coil 3 is wound around a semi-annular iron core 2 to form a current transformer element. The current transformer element is housed and fixed at a predetermined position in the molding dies 1a and 1c.

In this case, the molding die 1c is provided with a recess 11c having a depth H at a predetermined position outside the current transformer element in the radial direction, for example, at a position facing the uppermost part of the coil 3. The recessed portion 11c is provided with a screw type push pin 6 that moves back and forth in and out of the molding die 1c. On the other hand, in the uppermost portion of the coil 3 of the current transformer element facing the recess 11c of the molding die 1c, a size larger than the distance between the circumferential surface of the coil 3 and the inner surface of the molding die 1c is set in advance. A semi-cured insulating spacer 15 made of the same material as the molding synthetic resin is attached and fixed with an adhesive.

Therefore, the current transformer element is molded into a mold 1
In housing and fixing in the a and 1c, the split surface of the iron core 2 of the current transformer element is brought into contact with the molding die 1a, and the insulating spacer 15 is placed in the recess 1 of the molding die 1c.
Molds 1a and 1c for molding so as to be positioned inside 1c
Then, the molds 1a and 1c for molding are tightened by tightening bolts (not shown), and then the screw-type push pin 6 is screwed in. Press on the top to secure.

After the above assembling steps are completed, when the synthetic resin 4 is injected from a casting opening (not shown) of the molding die 1c and left for a certain period of time, and the injected synthetic resin 4 is in a semi-cured state, The screw type push pin 6 is pulled out or left as it is to release the molding dies 1a and 1c. At this time, a protruding portion including the insulating spacer 15 is formed in the mold coating layer made of the synthetic resin 4 due to the presence of the recessed portion 11c of the molding die 1c. The synthetic resin 4 for molding is completely cured. When the synthetic resin 4 is completely cured, the protruding portion formed on the mold coating layer is cut and removed by a cutting tool such as a grinder, and finishing is performed to obtain a resin mold split type current transformer. Two resin mold split type current transformers are combined to form a split type current transformer.

In the above embodiment, the mold dies 1a and 1c were released when the synthetic resin 4 was in a semi-cured state. However, when the synthetic resin 4 was completely cured, the mold metal 1a was released. The molds 1a and 1c may be released.

In this way, the molding die 1a,
When the synthetic resin 4 injected into 1c is in a semi-cured state, the resin is released from the mold, the screw type push pin 6 is pulled out, and the material of the same quality as the synthetic resin for molding is poured into the void portion to cure immediately. It is possible to shift to the process. Also, there is no need to perform the complicated work of positioning the current transformer elements using multiple insulating spacers.

FIG. 2 shows another embodiment of the present invention as set forth in claim 2, in which the current transformer elements constructed in the same manner as the above embodiment are housed in the molding dies 1d and 1e. A magnet 7 is fitted in the mold 1d at a position facing the split surface of the iron core 2 of the current transformer element.
And the current transformer element is housed and fixed at a predetermined position in the molding dies 1d and 1e. Therefore, mold 1 for molding
e does not have a screw type push pin.

Molding die 1 having such a structure
After completing the assembly of the current transformer elements using d, 1e,
Synthetic resin 4 from the casting port (not shown) of the molding die 1c
Is injected and left for a certain period of time, and when the injected synthetic resin 4 is in a semi-cured state or a cured state, the mold dies 1d and 1e are released. At this time, the mold coating layer made of the synthetic resin 4 is not provided with a screw type push pin or a concave portion in the molding die, so that a material of the same quality as the synthetic resin for the molding is poured into the void portion, or the protrusion is performed. There is no need to cut and remove parts. Also, there is no need to perform the work of positioning the current transformer element using a plurality of insulating spacers.

[0020]

As described above, according to the invention described in claim 1, a screw type push pin is provided in the recess of the molding die, and the current transformer is provided through the insulating spacer located in the recess. The element is housed and fixed in a predetermined position in the molding die, and when the synthetic resin injected into the molding die is cured, the protruding part formed in the mold coating layer is cut and removed. Since it is not necessary to pull out the push pin and pour a material of the same quality as the synthetic resin for molding into the void portion, and it is not necessary to position the current transformer element using a plurality of insulating spacers, It is possible to provide a method for manufacturing a resin mold split type current transformer which has improved workability and is economical.

According to the second aspect of the invention, since the current transformer element is housed and fixed in a predetermined position of the molding die by the magnet, it is not necessary to provide a screw type push pin in the molding die. Moreover, since it is not necessary to perform the work of positioning the current transformer elements by using a plurality of insulating spacers, it is possible to provide an economical method for manufacturing a resin mold split type current transformer with improved workability.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state at the time of manufacturing a resin mold split type current transformer according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state at the time of manufacturing a resin mold split type current transformer according to another embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing a state at the time of manufacturing a conventional resin mold split type current transformer.

[Explanation of symbols]

1a to 1e are molds, 2 is an iron core, 3 is a coil, 4 is a synthetic resin, 5 and 15 are insulating spacers, 6 is a screw type push pin, and 7 is a magnet.

Claims (2)

[Claims] 1. A current transformer element in which a secondary coil is wound around a semi-annular iron core is housed and fixed at a predetermined position in a molding die, and the current transformer element except for the iron core dividing surface is molded with a synthetic resin. In the method of manufacturing a resin mold split type current transformer for coating, a recess is provided inside the molding die located radially outside the current transformer element, and the molding die is placed inside and outside the recess. A screw type push pin that advances and retracts in the direction, an insulating spacer made of the same material as the molding resin is provided in the recess, and the current transformer element is molded by the screw type push pin through the insulating spacer. The mold is housed and fixed in a predetermined position, and then a synthetic resin is injected into the mold and cured, and then the mold is released, and then a mold coating including the insulating spacer is provided. A method of manufacturing a resin mold split type current transformer, characterized in that a protruding portion of a layer is removed. 2. A current transformer element, in which a secondary coil is wound around a semi-annular iron core, is housed and fixed at a predetermined position in a molding die, and the current transformer element excluding the iron core dividing surface is molded with a synthetic resin. In the method for producing a resin mold split type current transformer for coating, a magnet is attached to a predetermined position of the molding die, and the magnet is used to attract the core of the current transformer element to mold the current transformer element. The resin mold is divided into a plurality of molds and is fixed at a predetermined position in a molding die, and then a synthetic resin is injected into the molding die and cured, and then the molding die is released. Method of manufacturing a sink.