JPS59370B2 - Casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to casting molds, and in particular to controlling the injection rate thereof.

Generally, when casting a thermosetting resin (hereinafter simply referred to as a resin) such as an epoxy resin, the resin needs to be quickly poured into the mold because of the increase in viscosity due to reaction, and the resin must be poured into the mold quickly. When using a fast-curing resin such as a pressure gelling method, the cost will vary depending on the size of the cast product, etc.
Typically, very fast injection speeds, such as within 1 to 2 minutes, are required to fill the mold cavity with resin.

In order to increase the injection speed, the cross-sectional area of the flow path and the injection port may be increased, or the injection pressure may be increased. However, if the injection speed is increased for multi-cavity molded products or cast products with embedded objects whose positions are difficult to fix, in the former case, it is necessary to control the speed at which the resin is injected into each cavity through a branched flow path. In the latter case, there was a drawback that the implant could be moved or deformed. On the other hand, when the flow path of the casting resin also serves as a flow path to compensate for the shrinkage caused by the curing reaction of the resin in the cavity, and when the curing reaction is performed by receiving heat from the casting mold body, The resin flow path may harden earlier than the inside of the cavity, and as a result, the resin may not be replenished into the cavity, causing so-called whiskers on the product or uneven internal stress remaining. It was hot. This tendency is noticeable when the curing speed of the resin used is fast or when the cross-sectional area of the flow path of the resin is small.Especially when casting using the pressurized gelling method, the above phenomenon has a large effect on product performance. This made setting conditions difficult. In other words, if the cross-sectional area of the flow path is increased to prevent the resin from curing within the flow path, it becomes difficult to control the injection speed, whereas if the cross-sectional area of the flow path is decreased to control the injection speed, the flow path becomes difficult to control. They had contradictory characteristics, such as the resin hardening inside.

This invention, for example, arbitrarily controls the injection speed of resin in branched flow paths for casting resin, thereby providing a casting mold with a stable pourer and easy replenishment as the resin hardens and shrinks. The purpose is to obtain a mold for casting. FIG. 1 is a cross-sectional view showing an embodiment of the present invention, in which 1 is a mold body, 2 is a cavity formed in the body, and 3 is a sectional view showing an embodiment of the present invention.
4 is a molding surface thereof, 4 is a filler for guiding the casting resin, 5 is a branch passage branched from the flow path and connected to each cavity, 6 is provided in a removable state in this branch passage, A throttle member 7 having a flow port for controlling the injection speed of the resin is a deaeration hole for discharging gas from inside the cavity buoy 2 and the like.

In the casting mold configured as described above, the injected resin is guided to the branch channel 5, and is filled into the valley cavity 2 with the injection speed reduced by the flow port of the throttle member 6. be done. The injection speed of the resin injected into each cavity 2 is arbitrarily controlled mainly by changing the diameter of the flow port of the throttle member 6 or the injection pressure. Regardless of the cross-sectional area, the aperture member 6
is effectively controlled by the diameter of the flow opening. In this way, the injection rate of the resin is controlled and, for example, each cavity can be filled at the same time by making the time to fill each cavity constant, so that the injected resin wastefully overflows from a particular degassing hole. There is no leakage, and the injection speed can be increased, thus making it possible to perform casting in a short time. Although the embodiment shown in FIG. 1 is a multi-piece molded product with the same dimensions and shapes, the present invention can be suitably used even in cases where the dimensions and shapes are different.
Note that the aperture member 6 does not necessarily need to be provided in every branch channel, and may be attached to and detached from the mold body 1. By making it easier to perform delicate control of the injection rate, for example, prepare several types of throttle members with slightly different cross-sectional areas of the flow opening, and determine the injection rate by trial chain error. It is also possible to do so. FIG. 2 is a sectional view showing another embodiment of the present invention. In the figure, 1 to 7 indicate the same or equivalent parts as in the above embodiment, and 8 indicates a wire mesh electrode that is lightly held by the molding surface 3. , 9 is a center conductor, and both the wire mesh electrode and the center conductor are embedded in the injected resin 10. Note that G shown in the figure indicates the direction of gravity, and therefore the direction of the arrow indicates downward. Moreover, the above-mentioned FIG. 2 shows an example of a casting mold for making a capacitor-type bushing having a wire mesh electrode for electric field relaxation inside the cylindrical shape, in which the present invention is used. In the casting mold configured as described above, the casting resin injected from the flow path 4 is branched into a flow constriction member 6 provided in the branch path closest to the center conductor 9. Therefore, the injection speed is suppressed and the resin 10 in the middle of pouring increases as the distance from the center conductor 9 in the circumferential direction increases.
The surface of the wire mesh electrode 3 is adjusted so that it faces upward, and by performing the casting in this way, it is possible to effectively prevent the wire mesh electrode 3, which is the embedded object, from moving or deforming, such as lifting, and to reduce the injection speed of the resin. can be increased.

The present invention also applies when the flow path of the casting resin also serves as a flow path for compensating for shrinkage caused by the curing reaction of the resin in the cavity, as in the case of a pressure gelling method, for example. can be suitably used.

That is, even if the flow path of the injected resin is expanded to a cross-sectional area necessary to prevent hardening of the resin within the flow path, the injection speed can be effectively increased by using the throttle member having the flow port according to the present invention. can be controlled. In this case, for example, a material with low thermal conductivity is used for the partition member as necessary, and by providing a minute gap between the partition member and the mold body, the temperature of the resin in contact with the aperture member is approximately equal to that inside the flow path. It is possible to effectively prevent the injected resin that is in contact with or in the vicinity of the aperture member from curing. In FIG. 3, the aperture member according to the present invention is provided in contact with a cavity, and the surface of the aperture member in contact with the cavity is made a part of the molding surface of the cavity.

All the symbols shown in the figures represent the same or corresponding parts as in FIG. 1 above. By making the drawing member a part of the molding surface of the cavity as described above, the finished surface of the molded product can be limited to the opening area of the drawing member, which has another effect of making finishing easier. can be expected. By the way, in the above explanation, the case where this invention is utilized for casting thermosetting resin has been explained, but it goes without saying that it can be utilized for other purposes as well.

As described above, this invention has the effect of facilitating casting by providing a restricting member having a flow port in the fluid flow path.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the invention, and FIG. 3 is a sectional view showing still another embodiment of the invention. FIG. In the figure, 1 is a mold main body, 5 is a branch channel, and 6 is a throttle member having a flow port.

Claims (1)

[Scope of Claims] 1. A flow path branching from a flow path for guiding a fluid and connecting to one or more cavities, with at least one flow path for each cavity in the flow path leading to the cavity. A casting mold characterized by being provided with a drawing member. 2. The casting mold according to claim 1, characterized in that a thermosetting resin is used as the fluid. 3. The casting mold according to claim 1 or 2, characterized in that the throttle member is removable from the flow path. 4. The method according to claim 1 or 2, wherein a drawing member is provided in contact with the cavity, and the surface of the drawing member in contact with the cavity is at least part of the molding surface of the cavity. Casting mold. 5. The casting mold according to claim 1 or 2, characterized in that the aperture member is made of a material whose thermal conductivity is lower than that of the mold body.