JP4077289B2 - Resin injection nozzle for vacuum casting, resin injection device for vacuum casting, and resin injection method for vacuum casting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin injection nozzle, an injection device, and an injection method for injecting a resin into a mold in a vacuum vessel in the manufacture of a resin casting product used for, for example, an electrical insulator.
[0002]
[Prior art]
In recent years, epoxy resin cast products have been used in various fields because of their excellent electrical insulation and mechanical properties as solid insulators. For example, it is frequently used as an insulator for high-voltage power transformers, and long-term reliability is required. The epoxy resin casting product is manufactured by injecting epoxy resin into a mold in a vacuum vessel to prevent internal bubbles from remaining, suppress cracking, and improve dimensional accuracy. A vacuum casting method is used in which the pressure is increased (see, for example, Patent Document 1).
[0003]
A conventional general resin injection nozzle used for pressure production by such vacuum casting will be described with reference to FIGS. 3 shows a state where the injection valve is closed, and FIG. 4 shows a state where the injection valve is opened. That is, the mold 2 for resin molding is disposed inside the vacuum vessel 8. A resin injection nozzle 9 for introducing the resin 5 from the outside is inserted into the lower partition wall of the vacuum vessel 8. The resin injection nozzle 9 is provided so as to be movable up and down by a lifting hydraulic cylinder (not shown), and the tip of the resin injection nozzle 9 is configured to be able to contact and separate from the lower part of the mold 2 in accordance therewith.
[0004]
The resin injection nozzle 9 has a valve opening / closing mechanism 7 installed outside the vacuum vessel 8. The valve opening / closing mechanism 7 includes a movable shaft 11 disposed inside a resin injection nozzle 9 and an injection valve 3 that can be opened and closed by its vertical movement. The movable shaft 11 is driven by an opening / closing hydraulic cylinder (not shown) and descends to open the injection valve 3 and to inject the resin 5 into the mold 2 from the tip of the resin injection nozzle 9. The resin injection nozzle 9 and the sliding portion 12 of the movable shaft 11 are sealed with a packing 13.
[0005]
[Patent Document 1]
JP-A-6-114855 [0006]
[Problems to be solved by the invention]
By the way, in the conventional resin injection nozzle 9 as described above, the valve opening / closing mechanism 7 is installed outside the vacuum vessel 8, that is, in the atmospheric pressure atmosphere, and the movable shaft 11 attached to the external opening / closing hydraulic cylinder. Thus, the injection valve 3 is opened and closed by the vertical movement. Therefore, when the resin 13 is injected into the mold 2 in the vacuum vessel 8 and the packing 13 provided on the sliding portion 12 of the resin injection nozzle 9 and the movable shaft 11 is worn, FIG. As shown in FIG. 2, there is a possibility that the air 14 is sucked from the atmosphere and a vacuum leak occurs. In such a case, bubbles (microvoids) are generated inside the resulting epoxy resin casting. Such micro voids may affect the insulation performance and mechanical strength of electrical equipment used at high voltages.
[0007]
The present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to prevent the occurrence of vacuum leakage that occurs during resin injection, and to achieve high quality and reliable casting. An object of the present invention is to provide a resin injection nozzle for vacuum casting, a resin injection device, and a resin injection method capable of manufacturing a product.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes an injection port for injecting resin into a mold disposed in a vacuum vessel, a valve for opening and closing a resin flow passage to the injection port, possess a valve opening-closing mechanism for driving the valve, the resin injection nozzle for vacuum casting is provided said valve opening and closing mechanism in the vacuum chamber, together with the inlet away from said mold, said valve is closed A biasing member that biases in a direction, and a drive unit that drives the valve in a direction in which the valve opens while the inlet contacts the mold.
According to a third aspect of the present invention, there is provided a vacuum casting resin injection device comprising: a vacuum container; a mold disposed in the vacuum container; and a vacuum casting resin injection nozzle according to the first or second aspect. It is characterized by that.
According to a fourth aspect of the present invention, a method for injecting a resin for vacuum casting is characterized by producing a resin cast product using the resin injection nozzle for vacuum casting according to any one of the first or second aspect. And
In the inventions according to claims 1, 3 and 4 as described above, since the valve opening / closing mechanism through which air easily flows when the valve is opened / closed is disposed in the vacuum container in advance, the inflow of air does not occur, It is possible to prevent entrapment of minute voids that occur when the resin is injected, and to obtain a high-quality resin cast product. In addition, when the injection port comes into contact with the mold by the drive unit, the injection valve that was closed by the urging force of the urging member automatically opens, so the device is simplified compared to when the injection port and the valve are driven separately. it can.
[0010]
According to a second aspect of the invention, in the vacuum casting resin injection nozzle according to claim 1, wherein the flow path of the resin to the inlet, that the hollow shaft of the movable with said valve is provided Features.
In the invention according to claim 2 as described above, the valve opens and closes according to the movement of the hollow shaft provided in the resin flow passage, and therefore the valve opening and closing structure can be simplified.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
[First Embodiment]
[Constitution]
A first embodiment according to the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing a valve closed state in a resin injection device for vacuum casting, and FIG. 2 is a cross-sectional view showing a valve open state. That is, as shown in FIG. 1, the valve opening / closing mechanism 7 in the resin injection nozzle 9 of the present embodiment is installed in a vacuum vessel 8. The resin injection nozzle 9 is provided so as to be lifted and lowered by a lifting hydraulic cylinder, which is a driving unit (not shown), and the injection port 1 at the tip thereof is configured to be able to contact and separate from the lower part of the mold 2.
[0013]
Inside the valve opening / closing mechanism 7, there is provided a hollow shaft 6 for guiding a resin 5 pumped from a resin injection device or a tank (not shown) to the injection port 1. Under the hollow shaft 6, a resin injection nozzle 9 and an injection valve 3 that opens and closes as the hollow shaft 6 moves up and down are provided. The resin injection nozzle 9 is provided with a spring 4 that urges the injection valve 3 in the closing direction. Note that a seal portion is constituted by a packing 10 disposed in a packing groove at a joint portion of the resin injection nozzle 9 exposed to the outside of the vacuum vessel 8.
[0014]
[Action]
The procedure for opening and closing the injection valve 3 in the present embodiment having the above-described configuration is as follows. That is, at the time of non-injection when the injection port 1 is not in contact with the mold 2, the injection valve 3 is always closed by the pressure of the spring 4. When injecting resin from this state, as shown in FIG. 2, the resin injection nozzle 9 driven by the lifting hydraulic cylinder rises against the urging force of the spring 4, and the injection port 1 is made of gold. Touching mold 2. At this time, the hollow shaft 6 is also lifted together with the resin injection nozzle 9 and the injection valve 3 below is opened, so that resin injection is possible.
[0015]
The resin 5 pumped from the resin injection device or tank is injected into the mold 2 via the injection valve 3 and the hollow shaft 6. After the resin injection is completed, the driving force of the lifting hydraulic cylinder is released, and as shown in FIG. 1, the resin injection nozzle 9 is lowered by the biasing force of the spring 4, and the injection port 1 is separated from the mold 2. The injection valve 3 below the hollow shaft 6 is automatically closed.
[0016]
[effect]
According to the present embodiment as described above, the valve opening / closing mechanism 7 including the injection valve 3, the hollow shaft 6 and the like is all installed in the vacuum vessel 8. For this reason, the inside of the resin injection nozzle 9 is always kept in a vacuum state, and air is not drawn from the atmospheric pressure atmosphere at the time of resin injection. Therefore, the resin casting manufactured by this embodiment can be a good product that does not contain microvoids. In particular, for example, when the epoxy resin cast manufactured as described above is used as a solid insulator of an electric device used at a high voltage, it has excellent insulating performance and mechanical strength.
[0017]
Further, the combination of the lifting hydraulic cylinder and the spring 4 can raise and lower the resin injection nozzle 9 to bring the injection port 1 into and out of contact with the mold 2, and the hollow shaft 6 can be moved to open and close the injection valve 3. Therefore, the apparatus can be simplified as compared with the case where the injection port 1 and the injection valve 3 are driven separately.
[0018]
[Second Embodiment]
[Constitution]
Next, a second embodiment will be described. That is, in this embodiment, the space factor of the packing 10 in each seal part of the resin injection nozzle 9 is set to 90% or more. Other configurations are the same as those of the first embodiment shown in FIGS.
[0019]
[Function and effect]
According to the present embodiment as described above, the packing space factor in the seal portion is 90% or more, which is higher than the normal space factor of about 80%. Therefore, the air accumulation in the packing groove is reduced, and the occurrence of vacuum leakage can be more reliably prevented, so that a good resin cast product that does not contain microvoids can be manufactured.
[0020]
More specifically, the epoxy resin cast product obtained according to the present embodiment was confirmed to be free of microvoids on the outer periphery and inside in the appearance inspection and the X-ray inspection. Moreover, the result which has sufficient insulation performance was obtained also in the result of the partial discharge test (corona test).
[0021]
[Other Embodiments]
The present invention is not limited to the above-described embodiment, and the shape, size, number, arrangement, and the like of each member can be appropriately changed, and include various forms. For example, the resin flow path shape in the resin injection nozzle 9, the number of seal portions, and the like are arbitrary. The space factor of the packing 10 in the seal portion is not limited to the numerical values exemplified in the above embodiment, and can be a common sense value considering the balance with the strength of the resin injection nozzle 9 and the like. The urging member is not limited to an elastic member such as a spring as long as it can apply the urging force as shown in the above embodiment. Furthermore, if vacuum casting is possible, molded articles using various resins can be manufactured.
[0022]
【The invention's effect】
As described above, according to the present invention, the vacuum injection resin injection nozzle, the resin injection device, and the like that can prevent the occurrence of vacuum leakage that occurs at the time of resin injection and can manufacture a high-quality and highly reliable casting product. A resin injection method can be provided.
[Brief description of the drawings]
1 is a cross-sectional view showing a valve closed state of a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a valve open state of the embodiment of FIG. 1. FIG. 3 is a conventional resin injection device for vacuum casting. FIG. 4 is a cross-sectional view showing when the valve is closed in one example. FIG. 4 is a cross-sectional view showing when the valve is open in the conventional example of FIG.
DESCRIPTION OF SYMBOLS 1 ... Injection port 2 ... Mold 3 ... Injection valve 4 ... Spring 5 ... Resin 6 ... Hollow shaft 7 ... Valve opening / closing mechanism 8 ... Vacuum container 9 ... Resin injection nozzles 10, 13 ... Packing 11 ... Movable shaft 12 ... Sliding part 14 ... Air

Claims (4)

Possess an inlet for injecting a resin into arranged by type in a vacuum vessel, a valve for opening and closing the flow passage of the resin into the injection port, and a valve opening-closing mechanism for driving the valve, the valve opening and closing mechanism In the resin injection nozzle for vacuum casting provided in the vacuum vessel ,
A biasing member that biases the valve in a direction in which the valve closes while the inlet is separated from the mold;
A resin injection nozzle for vacuum casting, wherein the injection port is in contact with the mold and has a drive unit that drives the valve to open.   The resin injection nozzle for vacuum casting according to claim 1, wherein a movable hollow shaft provided with the valve is provided in a flow path of the resin to the injection port. A vacuum vessel;
A mold disposed in the vacuum vessel;
A vacuum casting resin injection apparatus comprising the vacuum casting resin injection nozzle according to claim 1.   A resin casting method for manufacturing a vacuum casting, wherein a resin casting product is manufactured using the resin injection nozzle for vacuum casting according to claim 1 or 2.

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