JPH09262881A - High pressure injection molding method and high pressure injection mold apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate weighing or compression without being restricted by the shape of a product in the so-called high pressure injection molding and to also enable the molding of multiple products. SOLUTION: In high pressure injection molding, a movable mold 2 is opened by resin pressure when a mold is filled with a resin R and, thereafter, mold clamping force is increased to close a gate 9 while closing the movable mold 2. By this constitution, pressure control and weighing are performed and the pressure and amt. of the resin in a cavity 3 become constant. The material passage 7 formed in a fixed mold 1 is allowed to directly communicate with the cavity 3 in order to shorten the material passage 7 so as to be capable of performing accurate weighing or compression. Therefore, the gate 9 is closed by fitting the protruding gate closing part 22 provided to the movable mold 2 in the leading end part 7a of the material passage 7. In order to enable accurate weighing or compression regardless of the shape of a product, the gate 9 is set to the position corresponding to the outside surface along a mold opening and closing direction of the product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method called high pressure injection molding (in-mold metering compression molding) and a mold apparatus used for the method, and more particularly to a method and a mechanism for opening and closing a gate.

[0002]

2. Description of the Related Art In the so-called high-pressure injection molding which has recently been adopted, as a cavity is filled with resin, the movable die is retracted in the opening direction by the resin pressure, and then the mold clamping force is increased. When the mold is finally closed, the mold structure is such that the gate closes midway.Until the gate is closed, the excess resin in the cavity is returned to the molding material supply device such as the heating cylinder and the gate is closed. After closing, the resin in the cavity is compressed. In this way, the amount and pressure of the resin in the cavity at the time when the gate is closed are made constant by the process of opening the movable mold by the resin pressure and the process of returning the resin in the cavity to the molding material supply device side (measurement and To regulate).

In the conventional high-pressure injection molding, for example, a movable plate is movably assembled to a fixed base in the mold opening / closing direction, and a spring is provided between the base and the movable plate so that the mold clamping force is weak. A material passage is formed between the moving plate and the movable die (die dividing surface) to strengthen the mold clamping force, and at the time of final die closing, the gate closing part provided in the fixed die causes the material passage to move to the cavity. The side gate of is closed.

[0004]

However, as described above, if the material passage is formed between the moving plate and the movable die, the material passage becomes longer by that much, and therefore the molding material reaching the cavity is formed. The hardening also becomes large. Therefore, during weighing and compression, the resin in the cavity cannot be smoothly returned to the molding material supply device side, accurate measurement cannot be performed, and the mold clamping force may be insufficient to compress the product to a predetermined size.

On the other hand, if the product has an opening,
It is also conceivable that the gate may be a direct gate located at a position corresponding to the opening hole, and a convex gate closing portion that is provided in a movable mold and forms the opening hole may be fitted to the gate to close the gate. However, this structure can be applied only to a product having an opening, and is not suitable for taking a plurality of products.

The present invention is intended to solve such problems, and it is a first object of the present invention to enable accurate weighing and compression in high-pressure injection molding without being limited by the shape of the product. To aim. In addition to that, the second purpose is to enable a plurality of pieces to be taken.

[0007]

In order to achieve the above object, the invention of claim 1 is a thermoplastic molding material in a cavity of a product shape formed between mold bodies in which a molding material supply device is closed. The molds move in the direction of opening each other as they are filled, and after the completion of the filling, the mold clamping force is strengthened to finally close the molds to each other, while the gate from the molding material supply device to the cavity is closed. In the high-pressure injection molding method, the molding material is directly filled in the cavity from a material passage formed in one mold body and communicating with the molding material supply device, at a position corresponding to an outer surface of the product along the opening / closing direction of the mold body. Then, when the mold clamping force is increased after the completion of filling, the gate closing part provided in another mold body is fitted into the tip of the material passage, so that the gate from the tip of the material passage to the cavity is closed. Close it is intended.

In high-pressure injection molding, the pressure of the molding material in the cavity becomes constant when the molding material is filled and the mold body is opened according to the pressure (pressure adjusting step). Then, when the mold is finally closed, the molding material in the cavity returns to the molding material supply device side, and when the gate is closed, a certain amount of molding material remains in the cavity (measurement step). Then, the molding material in the cavity is compressed (compression step).

By directly filling the molding material into the cavity from the material passage formed in one mold body, the material passage is shortened to reduce the hardening of the molding material to reach the cavity, and at the time of the measuring step. The molding material in the cavity can be smoothly returned to the molding material supply device side. As described above, in order to directly fill the cavity with the molding material from the material passage in one mold body, when closing the gate along with the final mold closure, the gate closing portion provided in the other mold body is connected to the tip of the material passage. However, by setting the gate at a position corresponding to the outer surface of the product along the opening / closing direction of the mold, the material passage in one mold is directly connected to the cavity without being limited by the product shape. It becomes possible to fill the molding material.

According to a second aspect of the present invention, in the high-pressure injection molding method of the first aspect of the invention, in order to achieve the second object as well, a plurality of cavities are formed between the mold bodies to form one mold body. When a molding material is filled into each of the cavities directly from a single material passage that is formed in the above and communicates with the molding material supply device, and when the mold clamping force is increased after completion of the filling, the gate closing portion provided in another mold body is closed. By fitting the tip of the material passage, the gate from the tip of the material passage to each of the cavities is closed at the same time.

In this way, sharing the material passage and the gate closing portion with respect to a plurality of cavities means that the gate is set at a position corresponding to the outer surface of the product along the opening / closing direction of the mold as described above. Is made possible by.

According to a third aspect of the present invention, there is provided a mold apparatus used in the high pressure injection molding method according to the first or second aspect, wherein the mold devices are opened and closed to form a cavity between the molds when the molds are closed.
And a second mold body, wherein the first mold body is provided with a material passage having a tip end having a direction along the opening / closing direction of the first mold body and the second mold body. The tip of the material passage is opened in the cavity at a position corresponding to the outer surface of the product along the opening / closing direction to form a gate, and the second
The mold closing body is provided with a gate closing portion for slidably fitting the tip of the material passage to open and close the gate.

With this configuration, during the filling and pressure adjusting steps, the cavity is directly filled with the molding material from the material passage in the first mold body at a position corresponding to the outer surface of the product along the opening / closing direction of the mold body. . Further, with the final mold closing, the gate closing part of the second mold body is fitted to the tip end part of the material passage, thereby closing the gate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described with reference to the drawings. First, the structure of the high-pressure injection molding die device will be described. Reference numeral 1 is a fixed mold which is a first mold body, 2 is a movable mold which is a second mold body, and these fixed mold 1 and movable mold 2 move in the vertical direction in the figure (hereinafter referred to as mold opening / closing direction). Are opened and closed, and a plurality of product-shaped cavities 3 are formed between them when the mold is closed. The fixed mold 1 is attached to a fixed side platen of a mold clamping device of an injection molding machine (not shown), and a plurality of the cavities 3 are formed on the surface of the fixed side mold plate 5 on the movable mold 2 side. Concave portions 6 are formed so as to be adjacent to each other and arranged radially. Further, inside the fixed mold 1, a single material passage 7 is formed between the plurality of recesses 6 and connected to a heating cylinder device which is a molding material supply device of an injection molding machine (not shown). ing. The material passage 7 has a valve casing 8 embedded in the fixed mold 1.
Formed within. The tip portion 7a of the material passage 7 on the side of the cavity 3 has a diameter smaller than that of the other portion of the material passage 7, and the side surface thereof has a hole shape parallel to the mold opening / closing direction. The tip 7a of the material passage 7 opens in each cavity 3 at a position corresponding to the outer surface of the product P to be molded, which is parallel to the mold opening / closing direction, and these openings form gates 9, respectively. Further, on the peripheral wall portion of the valve casing 8, there is provided a heater 10 as a heating means for keeping the thermoplastic resin R, which is a molding material for the material passage 7, in a constantly molten state.

A valve pin 11 which is a gate opening / closing member for opening / closing the gate 9 is incorporated in the fixed mold 1 so as to be movable in the mold opening / closing direction. The valve pin 11 is driven by a fluid pressure drive device 12 such as a hydraulic drive device, and is fitted into the tip end portion 7a of the material passage 7 so as to be insertable / removable and slidable. A relief passage 13 is formed at the tip of the valve pin 11 whose side surface is parallel to the mold opening / closing direction for fitting into the tip portion 7a of the material passage 7 and which leads from the tip surface to the side surface. The tip end surface of the valve pin 11 is an inverted taper surface 14 such as a conical surface, a spherical surface, or a pyramid surface that tapers toward the tip opening 13a of the escape passage 13 at the center thereof. Further, the side surface opening 13b of the escape passage 13 which is opened to the side surface of the valve pin 11 is located at a position where it is closed by the side surface of the tip end portion 7a of the material passage 7 when the valve pin 11 reaches the lower limit position in the fixed mold 1.

The movable mold 2 is attached to a movable platen of a mold clamping device (not shown).
On the surface of the fixed mold 1 side of the fixed mold 20, a convex part 21 that fits in each concave part 6 of the fixed mold 1 to form the cavity 3 is formed.
Are formed. The side surfaces of the concave portion 6 and the convex portion 21 are parallel to the mold opening / closing direction, and the volume of the cavity 3 can be changed by the mutual sliding of the concave portion 6 and the convex portion 21. Note that, contrary to the present embodiment, a convex portion is provided on the fixed mold,
A recess may be provided in the movable die. Further, the movable die 2 is fixed with a pin 23 having a gate closing portion 22 at its tip on the fixed die 1 side. The side surface of the gate closing portion 23 is parallel to the mold opening / closing direction, and the gate closing portion 23 is removably and slidably fitted into the tip end portion 7a of the material passage 7 of the fixed die 1, and the material passage 7 The gate 9 from the tip portion 7a of each of the above to each cavity 3 is simultaneously opened and closed. Further, the tip end surface of the gate blocking portion 22 has the same shape as the reverse tapered surface 14 of the valve pin 11,
The taper surface 24 that fits and abuts against the reverse taper surface 14
It has become.

The tip portion 7a of the material passage 7 and the valve pin
The cross-sectional shape of 11 and the gate closing portion 22 may be substantially circular as shown in FIG.
As shown in (a), it may be substantially rectangular,
It can be set appropriately.

Further, on the fixed mold 1 side of the movable side mold plate 20, a pressure plate 31 abutting against the fixed side mold plate 5 and the movable side mold plate 20 is assembled so as to be movable in a predetermined range in the mold opening / closing direction. . The pressing plate 31 is applied with a force in the opening direction with respect to the movable side mold plate 20 by a spring 32 as an urging means. In addition, the convex portion 21 of the movable side template 20
Penetrates the pressure plate 31 slidably. The pressure plate may be provided on the fixed mold 1 side instead of the movable mold 2 side.

Next, a high pressure injection molding method using the mold apparatus will be described. 3 to 6, the flow of the resin R and the movements of the movable die 2 and the valve pin 11 are indicated by arrows. Through opening and closing of the mold, the thermoplastic resin R, which is the molding material in the material passage 7 in the mold device,
It is kept in a molten state by heating the heater 10.

Then, the mold clamping device first closes the fixed mold 1 and the movable mold 2 with a weak mold clamping force. As a result, FIG.
As shown in FIG.
The respective convex portions 21 of 20 are fitted into each other, and a plurality of cavities 3 are formed between the fixed mold 1 and the movable mold 2. At the same time, the pressure plate 31 abuts the fixed-side mold plate 5, but the balance between the spring 32 and the mold clamping force causes the pressure plate 31 to move.
Is not hitting. When the mold is closed in this way, the valve pin 11 that has closed the gate 9 until then, as shown in FIG.
Is raised in the fixed mold 1 by the drive of the fluid pressure drive device 12, and the gate 9 is opened. In this state, the resin R melted by heating is injected from the heating cylinder device into the material passage 7. The resin R is filled from the common single material passage 7 through the gate 9 into each cavity 3 (filling step).

In the case of an in-line screw type, for example, the resin R is supplied from the heating cylinder device until the screw reaches a predetermined position such as the forward limit. Along with this, the resin pressure in the cavity 3 pushes down the movable mold 2 against the mold clamping force as shown by the solid line and the chain line in FIG. 3, and the fixed mold 1 and the movable mold 2 open. This opening amount is determined by the balance between the resin pressure in the cavity 3 and the force of the spring 32 and the mold clamping force, and becomes larger as more resin R is filled in the cavity 3. In other words, even if there is an error in the amount of the resin R supplied from the heating cylinder device, the error is absorbed by the change in the opening amount, and the pressure of the resin in the cavity 3 is adjusted and becomes constant (pressure adjustment). Process).

After that, the mold clamping force applied to the fixed mold 1 and the movable mold 2 by the mold clamping device is strengthened. This allows the movable mold 2
Rises and the movable mold 2 closes with respect to the fixed mold 1. When the fixed mold 1 and the movable mold 2 are finally closed, the excess resin R in the cavity 3 is discharged from the gate 9 which is still open from the material passage 7 by the final mold closing. Then, the resin R in the material passage 7 returns to the heating cylinder device. Then, as shown in FIG.
When the gate closing portion 22 of the above starts to be fitted into the tip end portion 7a of the material passage 7, each gate 9 is closed, and at this time, a certain amount of the resin R remains in the cavity 3 (measurement step). After that, the pressure plate 31 and the movable side mold plate 20 are closed until they abut each other, and accordingly, as shown in FIG. 5, the resin R in the cavity 3 is pressed and compressed (compression step).

After that, the valve pin 11 of the fixed mold 1 is lowered by the drive of the fluid pressure driving device 12, and is fitted into the tip end portion 7a of the material passage 7. At that time, the resin R between the tip surfaces of the valve pin 11 and the gate closing portion 22 is pressed to release the resin R.
Return to the material passage 7 in the valve casing 8 through 13.
And finally, the reverse taper surface at the tip of the valve pin 11
The resin 14 does not remain between the tip end surfaces of the valve pin 11 and the gate blocking portion 22 by fitting the tapered surface 24 of the gate blocking portion 22 against the tapered surface 24. At this time, the tip end surface of the valve pin 11 is the reverse taper surface 14 that becomes narrower toward the tip opening 13a of the escape passage 13, and the tip end surface of the gate closing portion 22 is the corresponding taper surface 24. The resin R between the tip surfaces of the valve pin 11 and the gate blocking portion 22 is guided by the reverse taper surface 14 and the taper surface 24, and the escape path is formed.
The valve casing 8 is smoothly guided to the tip opening 13a of the valve casing 13.
Return to the material passage 7 inside.

After the resin R in the cavity 3 is sufficiently cooled and solidified, the mold is opened as shown in FIG. For a short while after this mold opening is started, the fluid pressure drive device 12
The valve pin 11 is lowered together with the movable mold 2 by driving the. When the valve pin 11 reaches the lower limit of the fixed mold 1, the side opening 13b of the escape path 13 of the valve pin 11 is opened.
Is closed by the side surface of the tip end portion 7a of the material passage 7. Until then, the state where the reverse taper surface 14 of the valve pin 11 and the taper surface 24 of the gate blocking portion 22 abut against each other is maintained. In this way, when the fixed die 1 and the movable die 2 are open, the side opening 13b of the escape passage 13 is closed and the escape passage 13 is cut off from the material passage 7 in the valve casing 8. The resin R which is in a molten state in the material passage 7 does not leak from the tip end opening 13a of the escape passage 13. Although the resin R remains in the escape passage 13 and the resin R is also kept in a substantially molten state, the volume of the escape passage 13 is very small, and the escape is blocked from the material passage 7. Since no great pressure is applied to the path 13,
The resin R inside does not leak out from the tip end opening 13a. Even if it leaks out, it is a small amount and does not cause malfunction of the mold device or molding failure.

When the mold is opened, the resin R in the cavity 3, that is, the product P, first separates from the fixed mold 1. After that, the ejection mechanism (not shown) provided on the movable die 2 side ejects the product P, and the product P is released from the movable die 2. At the same time, a take-out device (not shown) takes out the product P from the mold device. Thereafter, the mold is closed again, and the above steps are repeated.

According to the high-pressure injection molding as described above, a high-precision product P having stable quality can be obtained by the pressure adjusting process and the measuring process. Further, since the density is increased by the compression step, a product P excellent in mechanical properties and optical properties can be obtained.

Further, in this mold apparatus, since the tip end portion 7a of the material passage 7 in the fixed die 1 directly communicates with the cavity 3, the material passage in the fixed die is further passed through the material passage formed on the mold dividing surface. Material passage 7 rather than reaching the cavity
Can be shortened as a whole. Therefore, the resin R in the cavity 3 can smoothly return to the material passage 7 during the measuring step due to less hardening of the resin R due to cooling until reaching the cavity 3. The resin R can smoothly return to the heating cylinder device 12. At the same time, the resin R in the cavity 3 is smoothly compressed after the measuring step, and the mold clamping force of the mold clamping device may be relatively low. Therefore, the metering and compression can be accurately performed without impairing the pressure regulation result in the pressure regulation process, and the features of the high pressure injection molding can be maximized.
Further, since the resistance is small, the time required for the measuring step and the compression step is shortened, which is also advantageous in increasing the speed of the molding cycle.

Moreover, since the resin R in the material passage 7 in the mold apparatus is always kept in a molten state by the heating of the heater 10, the resin R in the cavity 3 becomes even smoother during the measuring step. The resin R in the material passage 7 can return to the heating cylinder device 12 more smoothly. Therefore, the above-mentioned effects such as accurate measurement and compression can be further utilized.

Further, the tip of the material passage 7 in the fixed mold 1
In order to directly communicate 7a with the cavity 3, the gate 9 is closed by fitting the convex gate closing portion 22 of the movable mold 2 to the tip end portion 7a of the material passage 7 with the final mold closure. However, since the gate 9 is formed by arranging the tip end portion 7a of the material passage 7 at a position corresponding to the outer surface of the product P along the mold opening / closing direction, the shape of the product P is not limited. The tip 7a of the material passage 7 in the fixed mold 1 can be directly communicated with the cavity 3. For example, even if the product P has no opening, the material passage 7 in the fixed mold 1
The tip portion 7a of the can be directly communicated with the cavity 3.

At the same time, forming the gate 9 by arranging the tip end portion 7a of the material passage 7 at a position corresponding to the outer side surface of the product P along the mold opening / closing direction means forming the gate 9 even if a plurality of pieces are taken. It is possible to directly communicate the tip portion 7a of the single material passage 7 in each cavity 3 with each other. Then, the gate 9 to each cavity 3 can be simultaneously opened and closed by one common gate closing portion 22 and valve pin 11.
As a result, the mold apparatus can be downsized and the structure of the mold apparatus can be simplified.

Further, as described above, the gate closing portion 22 is fitted to the tip end portion 7a of the material passage 7 during the metering process to the compression process, while the gate 9 is closed by the valve pin 11 when the mold is opened. On the other hand, when the valve pin 11 is fitted into the gate 9, the escape passage 13 formed in the valve pin 11 returns the resin R between the tip end surfaces of the valve pin 11 and the gate closing portion 22 into the material passage 7. It is possible to prevent the resin R from remaining between the tip surfaces of the valve pin 11 and the gate closing portion 22 and leaking out when the mold is opened. Moreover, since the side surface opening 13b of the escape passage 13 is closed by the side surface of the tip end portion 7a of the material passage 7 when the mold is opened, the gate 9 can be reliably closed. In this way, the reliability of the mechanism for opening and closing the gate 9 can be maintained.

The present invention is not limited to the above embodiment, but various modifications can be made. For example,
In the above-mentioned embodiment, the resin R in the material passage 7 of the fixed mold 1 is always kept in a molten state by heating, but the resin in the material passage is solidified by cooling before the mold is opened, and the product is opened when the mold is opened. You may take out with it. Further, as already described, the product shape is not limited to the square shape as shown in the drawing, but may be a circular shape or the like, and the present invention can be applied to products of almost any shape. Further, the number of pieces to be taken is not limited to four as shown in the figure, and an appropriate number such as two or three is possible. However, it is necessary that the cavities can be arranged radially. Further, the present invention is applicable not only to injection molding of thermoplastic resins but also to injection molding of thermoplastic molding materials in general, such as injection molding of ceramics using a thermoplastic resin as a binder and injection molding powder metallurgy. Furthermore, the mold clamping device and the material supply device of the injection molding machine can also have various configurations.

[0033]

According to the first aspect of the present invention, in the high-pressure injection molding method, the molding material is directly filled into the cavity from the material passage formed in one mold, so that the material passage can be shortened, and thus the filling is completed. When the rear mold clamping force is increased, the molding material in the cavity returns to the molding material supply device side smoothly, and the molding material in the cavity is smoothly compressed, so that the weighing and the compression can be accurately performed. Also, 1
In order to fill the molding material into the cavity directly from the material passage in one mold body, when closing the gate with the final mold closing, the gate closing part provided in the other mold body is fitted to the tip of the material passage. However, since the gate was set at a position corresponding to the outer surface along the opening and closing direction of the mold in the product,
Regardless of the product shape, the cavity can be filled with the molding material directly from the material passage in one mold.

At the same time, by setting the gate at a position corresponding to the outer side surface of the product along the opening / closing direction of the mold, a plurality of material passages and gate closing portions are shared as in the invention of claim 2. Individual picking is possible, and at that time, the effect of the invention of claim 1 can be maintained. Further, by sharing the material passage and the gate closing portion, it is possible to obtain effects such as downsizing of the die device and simplification of the structure.

According to the mold apparatus for high-pressure injection molding of the third aspect of the present invention, the tip end portion of the first die body has a direction along the opening / closing direction of the first die body and the second die body. A material passage is formed, and a tip of the material passage is opened in a cavity at a position corresponding to an outer surface of the product along the opening / closing direction to form a gate, and the second mold body slides on the tip of the material passage. Since the gate closing part that freely fits and opens and closes the gate is provided, as described above, in high pressure injection molding, accurate weighing and compression can be performed without being limited by the shape of the product, and It is also possible to take multiple pieces.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a high-pressure injection molding die device of the present invention, showing a state immediately after a mold is closed.

FIG. 2 is a schematic plan view of the movable type as above, FIG.
(B) shows examples in which the shape of the gate closing portion is changed.

FIG. 3 is a vertical cross-sectional view of the vicinity of the gate, showing a filling step and a pressure adjusting step.

FIG. 4 is a vertical cross-sectional view of the vicinity of the gate, showing the time when the weighing process is completed.

FIG. 5 is a vertical cross-sectional view of the vicinity of the gate, showing the time when the compression step is completed.

FIG. 6 is a vertical cross-sectional view of the vicinity of the gate, showing the state immediately after the start of mold opening.

FIG. 7 is a transverse sectional view of the valve pin of the above.

[Explanation of symbols]

 1 Fixed type (one type body, first type body) 2 Movable type (other type body, second type body) 3 Cavity 7 Material passage 7a Material passage tip 9 Gate 22 Gate block R Thermoplastic Resin (molding material) P product

Claims (3)

[Claims] 1. A molding material supplying device moves the mold bodies in a direction to open each other as the molding cavities formed between the closed mold bodies are filled with the thermoplastic molding material. In the high-pressure injection molding method, in which the mold clamping force is strengthened after completion and the mold bodies are finally closed to each other, and the gate from the molding material supply device to the cavity is closed in the meantime, the molding material supply device is formed in one mold body. When the mold material is directly filled in the cavity at a position corresponding to the outside surface of the product along the opening / closing direction of the mold from the material passage leading to the mold, and the mold clamping force is increased after completion of the filling, the mold is provided in another mold. A high-pressure injection molding method, characterized in that the gate closing portion is fitted to the tip of the material passage to close the gate from the tip of the material passage to the cavity. 2. A plurality of cavities are formed between the mold bodies, and each cavity is directly filled with the molding material from a single material passage formed in one mold body and communicating with the molding material supply device. When the rear mold clamping force is increased, the gate closing portion provided on another mold body is fitted to the tip of the material passage, thereby simultaneously closing the gates from the tip of the material passage to the cavities. The high-pressure injection molding method according to claim 1, wherein 3. A mold apparatus used in the high-pressure injection molding method according to claim 1, wherein the first mold body and the second mold body are opened and closed to form a cavity between them when the mold is closed.
And a tip end portion of the material passage is formed in the first die body, and the tip portion of the material passage has a directivity along the opening / closing direction of the first die body and the second die body. A gate is opened in the cavity at a position corresponding to the outer surface of the product along the opening / closing direction, and is slidably fitted to the tip of the material passage in the second mold body to open / close the gate. A mold device for high-pressure injection molding, characterized in that a gate closing portion is provided.