JP3629977B2 - Manufacturing method of resin molded product by injection molding and injection mold - Google Patents

Description

【００２１】
図１１に、可動コア４にヒータ１４を内蔵した実施例を示す。この実施例は、可動コア４を移動させてランナ２の厚みを薄くする過程で、ランナ２にある樹脂の肉厚が薄くなるに従い金型に熱を奪われ流動性を失い易いガラス繊維充填熱可塑性樹脂等に適用する。成形手順は上述した手順と同じである。
【００２２】
【発明の効果】
上述のように、本発明に係る製造法は、ランナ空間に残る樹脂を大幅に削減でき、省資源及び廃棄物低減に大きく貢献できるものである。その方法は、ランナ空間に残っている樹脂が溶融状態にある間に可動コアを移動させるものであるから、成形条件の最適設定範囲を広げることが可能である。断熱ランナ方式の如き複雑な構造の成形金型も必要としないから、適用できる樹脂材料の種類と金型製作費用を下げ金型保守・保全性も改善することができる。
【図面の簡単な説明】
【図１】本発明の実施例に係る射出成形金型の側面断面図である。
【図２】本発明の実施例に係る射出成形金型の可動側金型正面図である。
【図３】図２のＡ−Ａ’線に沿うランナ部の金型断面図であり、可動コア４の移動前（樹脂射出中）と移動後（樹脂射出後）の状態を示す図である。
【図４】本発明の実施例に係る射出成形の手順を示し、手順１における射出成形金型の側面断面図である。
【図５】同手順２における射出成形金型の側面断面図である。
【図６】同手順３における射出成形金型の側面断面図である。
【図７】同手順４における射出成形金型の側面断面図である。
【図８】同手順５における射出成形金型の側面断面図である。
【図９】同手順６における射出成形金型の側面断面図である。
【図１０】本発明の実施例に係る射出成形の手順において、手順２，３，４，６における可動コア４とスプルロックピン６の協働関係の詳細を示す断面図である。
【図１１】本発明の他の実施例に係る射出成形金型の側面断面図である。
【符号の説明】
１は成形キャビティ
２はランナ
３はスプル
４は可動コア
５は突き出しピン
６はスプルーロックピン
７は成形機の突き出し装置
８は可動コア板
９は突き出し板
１０は凹陥部
１１は成形機の射出ノズル
１２は成形品
１３はスプル及びランナ部樹脂
１４はヒータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a resin molded product by injection molding capable of reducing unnecessary resin other than the molded product, and an injection mold.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in the manufacture of a molded product by resin injection molding, there is a heat insulating runner method as a means for reducing resin material that becomes waste. In this system, a heat insulating material is interposed between a molding cavity of a mold and a runner that is a passage for a molten resin filling the molding cavity. A mold having a structure in which a molding cavity and a runner are separated by a heat insulating material is used. On the one hand, the mold temperature is controlled so that the resin staying in the runner always maintains fluidity, and on the other hand, the mold temperature is controlled so that the resin filled in the molding cavity is properly cooled and solidified. To do. While the resin in the runner is always kept in a fluid state, the resin filled in the molding cavity is cooled and solidified in the case of a thermoplastic resin, and the thermosetting reaction is advanced in the case of a thermosetting resin. It is a method to obtain. This method has an advantage that the resin material is not wasted because the resin remaining in the runner is filled in the molding cavity in the next molding cycle and used to mold the molded product.
[0003]
By the way, in this method, it is important to always maintain the resin in the runner in an appropriate flow state. Therefore, it is not suitable for a resin such as a thermosetting resin in which the thermosetting reaction proceeds with time and the fluidity is lowered. Also, in this system, it is important to keep the gate that separates the molding cavity and the runner, maintain the resin in a fluid state on the runner side, and cool the resin to the solid on the molding cavity side. There is a problem that it is difficult to control the temperature of the gate. If the optimal temperature control setting range is narrow and the temperature control is not appropriate, the fluidity of the resin in the runner will decrease while waiting for the resin filled in the molding cavity to solidify, making it impossible to inject in the next molding cycle. Conversely, the resin filled in the molding cavity is insufficiently solidified, and deformation of the molded product is likely to occur.
Therefore, in the above-described heat insulating runner method, a needle-like valve is often used for the gate, and the runner and the molding cavity are often separated. However, since this needle-shaped valve is composed of precision parts, it cannot be applied to injection molding of a resin material that easily causes mold wear, such as a resin reinforced with glass fiber.
[0004]
As described above, in the method for producing a resin molded product by the heat insulating runner method, there are problems that the optimum setting range of the molding conditions is narrow and unstable, and the types of resin materials that can be applied are limited. Insulating runner molds require complex structures and precise mold temperature control, which increases the cost of mold production and leaves resin in the runner after molding. There is a problem in maintenance and maintainability such as taking time and effort to remove the resin during disassembly and cleaning.
[0005]
[Problems to be solved by the invention]
Therefore, the present invention solves the problems of the heat insulating runner method when performing injection molding to reduce the resin material that becomes waste, expands the optimum setting range of the types of resin material and molding conditions that can be applied, Lower mold production costs and improve mold maintenance and maintainability.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the method according to the present invention is to fill a molding cavity with a molten resin through a sprue and runner from a nozzle for injecting the molten resin, wait for the resin to solidify, open the mold, and In manufacturing the resin molded product to be taken out, a part of the mold member constituting the runner space is made a movable core, and the corresponding position of the movable core facing the sprue is constituted by a sprue lock pin whose operation is independent from the movable core. While the resin in the runner retains fluidity after filling the molding cavity with molten resin, the movable core is driven to narrow the runner space , while the sprue lock pin does not move and remains in its original position. by left, the movable core portions are you with recesses resin remained.
When the movable core is driven so as to narrow the runner space, the resin in the runner is pushed into the molding cavity, and the thickness of the resin remaining in the runner is reduced. It is possible to reduce the resin remaining in the runner that is unnecessary and is discarded or regenerated after the molding. A thin film-like resin remains on the runner, which is continuous with the resin remaining in the movable core recess, and all remains on one side when the mold is opened after molding. Then, at the stage of returning the movable core to the original position, the resin remaining in the concave portion of the movable core is protruded by the sprue lock pin, and the sprue part and the runner part resin are dropped from the mold together. The manufacturing method according to the present invention focuses on the fact that the resin in the runner retains fluidity for a while even after the molding cavity is filled with the molten resin. The movable core only needs to be driven while the resin in the runner retains fluidity after filling the mold cavity with molten resin, so the mold temperature control with high accuracy required for the heat insulating runner method is required. There is no need for.
[0007]
The injection mold used in the above manufacturing method uses a movable core as a part of a mold member constituting the runner space, and reversibly narrows the size of the runner space from the state at the time of molten resin injection. Means are provided. If the movable core is provided with a heater and an ultrasonic oscillation device and these are operated, it is convenient because the solidification of the resin in the runner can be delayed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
According to the method of manufacturing a resin molded product by injection molding according to the present invention, a resin material is plasticized by an injection molding machine, and after filling an appropriate amount of a molten resin into a molding cavity, the resin in the runner has flowability for a while. Focus on holding. After filling the molding cavity with molten resin, before the resin in the runner loses its fluidity due to cooling solidification or thermosetting reaction, the runner space is forcibly narrowed and the resin in the runner space is pushed into the molding cavity. . A part of the mold member that constitutes the runner space is used as a movable core, and as a movable core drive means, a molding product ejecting mechanism of a molding machine is used, or a drive device is separately provided in the mold to move the movable core. Is reversibly reduced from the state at the time of injection of the molten resin. Only a thin film-like resin remains in the runner, and unnecessary and waste resin can be reduced.
[0009]
When the resin to be injection-molded is thermosetting, the fluidity of the resin in the runner is relatively good and the fluidity is maintained for a long time. By driving the movable core, the thickness of the resin remaining in the runner can be easily Can be thin. On the other hand, when the resin to be injection-molded is thermoplastic, if the resin remaining in the runner is reduced by driving the movable core, the heat of the resin is easily taken away by the mold, and the resin is rapidly cooled and solidified. Proceed to Once the resin has cooled and solidified, the runner space cannot be further narrowed. Therefore, it is preferable that the movable core is provided with a heater so that the temperature is higher than that of the surrounding mold members so that the resin remaining in the runner can maintain fluidity for a long time. As a result, the resin remaining in the runner can be made into a thin film. The fluidity of the resin remaining in the runner can also be maintained by attaching an ultrasonic oscillator to the movable core instead of the heater and applying ultrasonic vibration to the resin remaining in the runner.
[0010]
【Example】
An embodiment of an injection mold according to the present invention is shown in FIGS. FIG. 1 is a side sectional view of the mold, and FIG. 2 is a front view of the movable mold.
This mold is for producing eight cylindrical molded products by one molding. As shown in FIG. 2, a ladder-like runner 2 is provided to distribute and fill the resin into each of the eight molding cavities 1. A part of the mold member for constituting the runner space is set as the movable core 4 processed according to the shape of the runner. The injection nozzle 11 of the molding machine is connected to the sprue 3 and the runner 2, and the part directly below the sprue 3 is constituted by a member (sprue lock pin 6) independent of the movable core 4. The movable core 4 is fixed to the movable core plate 8, and the movable core plate 8 is interlocked with the extrusion device 7 of the molding machine. By the operation of the ejecting device 7, first, the movable core 4 can be moved 3.8 mm in the right direction in FIG. 1, and the thickness of the space of the runner 2 is reduced from 4 mm to 0.2 mm. This operation is performed while the resin in the runner 2 retains fluidity after the molding cavity 1 is filled with molten resin. FIG. 3 is a mold cross-sectional view of the runner along the line AA ′ in FIG. 2, and shows a state before the movable core 4 is moved (during resin injection) and after the movement (after resin injection). This shows that the space of the runner 2 is narrowed after the resin injection.
[0011]
Further, the movable core plate 8 is interlocked with a protruding plate 9 that operates with a delay of 3.8 mm from the movable core plate 8, and the protruding device 7 of the molding machine is moved 3.8 mm to the right in FIG. 1. When driven beyond, the movable core plate 8 is pushed to move the protruding plate 9 to the right in FIG. 1 so that the molded product protruding pin 5 is activated.
[0012]
The procedure of the injection molding of the embodiment according to the present invention will be described below in order.
Procedure 1 (Fig. 4)
Tighten the mold attached to the molding machine. In this state, the movable core 4 is at the leftmost position in the figure, and the runner 2 has a thickness of 4 mm. The state has already been described with reference to FIG.
[0013]
Procedure 2 (Fig. 5)
An appropriate amount of molten resin material is injected from the injection nozzle 11 of the molding machine, and filled into the molding cavity 1 through the sprue 3 and the runner 2.
[0014]
Step 3 (Figure 6)
After the procedure 2, while the resin in the runner 2 is in a molten state, the ejector 7 is driven to move the movable core 4 through the movable core plate 8 to the right side of the figure by 3.8 mm. Narrow the space and push the resin there into the molding cavity 1. The runner 2 has a thickness of 0.2 mm. Since the sprue lock pin 6 does not move and is in its original position, the resin remains in a small recess formed by the movement of the movable core 4 (the tip of the sprue lock pin 6 is the bottom). In this state, the injection pressure is maintained until the resin in the molding cavity 1 is solidified.
[0015]
Step 4 (Figure 7)
Open the mold. All of the injected resin remains in the mold on the molding cavity 1 side.
[0016]
Step 5 (Figure 8)
The ejecting plate 9 is pushed by the movable core plate 8 by further driving the ejecting device 7 to the right in the figure. The protruding pin 5 is moved in the right direction in the figure through the protruding plate 9, and the molded product 12 is protruded from the molding cavity 1 and taken out. At this time, the movable core 4 and the sprue lock pin 6 move in the right direction of the figure in the same manner as the protruding pin 5. The sprue lock pin 6 is moved through the protruding plate 9.
[0017]
Step 6 (Figure 9)
By driving the ejection device 7 in the opposite direction (left direction in the figure), the movable core 4, the ejection pin 5 and the sprue lock pin 6 are returned to the original leftmost position in the figure. First, since only the movable core 4 moves 3.8 mm in the left direction in the figure, the resin remaining in the small concave portion in the procedure 3 is protruded by the sprue lock pin 6. As a result, the sprue and the runner resin 13 fall off from the mold (the runner resin has a thickness of 0.2 mm). When the movable core 4 moves beyond 3.8 mm in the left direction in the figure, the protruding plate 9 is pushed by the movable core plate 8, and the protruding pin 5 and the sprue lock pin 6 move in the left direction in the figure.
In this way, one molding is completed.
[0018]
Next, details of the cooperative relationship between the movable core 4 and the sprue lock pin 6 will be described with reference to FIG.
In the procedure 2 described above, the upper surface of the sprue lock pin 6 located immediately below the movable core 4 and the sprue 3 is on the same plane, and constitutes the space of the runner 2. On the sliding surface of the movable core 7 with the sprue lock pin 6, a small recess 10 is formed at a position slightly lowered from the upper surface.
In step 3, when the movable core 4 is moved 3.8 mm in the right direction in the figure, the sprue lock pin 6 does not move and is in its original position. Therefore, a small recess formed by the movement of the movable core 4 (the sprue lock pin 6 The resin remains on the bottom of the top). At this time, the recessed portion 10 is filled with resin, and a slight undercut portion is formed.
When the mold is opened in step 4, the sprue and runner resin 13 are held in the undercut portion and remain in the mold on the molding cavity 1 side.
In the procedure 6, first, only the movable core 4 moves 3.8 mm in the left direction in the figure, so that the sprue and runner resin 13 are protruded by the sprue lock pin 6 (forcibly removed). As a result, the sprue and the runner resin 13 fall off from the mold.
[0019]
Table 1 shows a comparison of the required resin weight between the above-described example and the conventional example (when the movable core 4 is not moved). In the embodiment according to the present invention, the amount of sprue and runner resin is reduced from 15.7 g to 1.2 g, and the reduction rate is 92%.
[0020]
[Table 1]

[0021]
FIG. 11 shows an embodiment in which the heater 14 is built in the movable core 4. In this embodiment, in the process of moving the movable core 4 to reduce the thickness of the runner 2, the glass fiber filling heat that easily loses fluidity due to heat being taken away by the mold as the resin thickness in the runner 2 becomes thinner. Applies to plastic resins. The molding procedure is the same as that described above.
[0022]
【The invention's effect】
As described above, the production method according to the present invention can greatly reduce the resin remaining in the runner space, and can greatly contribute to resource saving and waste reduction. Since the method moves the movable core while the resin remaining in the runner space is in a molten state, it is possible to widen the optimum setting range of molding conditions. Since a molding die having a complicated structure such as a heat-insulating runner method is not required, the type of applicable resin material and die manufacturing cost can be reduced, and die maintenance and maintainability can be improved.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an injection mold according to an embodiment of the present invention.
FIG. 2 is a front view of a movable mold of an injection mold according to an embodiment of the present invention.
3 is a mold cross-sectional view of a runner portion along the line AA ′ in FIG. 2, and shows a state before the movable core 4 is moved (during resin injection) and after the movement (after resin injection). FIG. .
FIG. 4 is a side cross-sectional view of an injection mold in Procedure 1 showing an injection molding procedure according to an embodiment of the present invention.
FIG. 5 is a side cross-sectional view of an injection mold in the same procedure 2;
6 is a side cross-sectional view of the injection mold in the same procedure 3. FIG.
7 is a side sectional view of an injection mold in the same procedure 4. FIG.
FIG. 8 is a side cross-sectional view of the injection mold in the same procedure 5.
9 is a side cross-sectional view of the injection mold in the same procedure 6. FIG.
FIG. 10 is a cross-sectional view showing details of the cooperative relationship between the movable core 4 and the sprue lock pin 6 in steps 2, 3, 4 and 6 in the procedure of injection molding according to the embodiment of the present invention.
FIG. 11 is a side sectional view of an injection mold according to another embodiment of the present invention.
[Explanation of symbols]
1 is a molding cavity 2 is a runner 3 is a sprue 4 is a movable core 5 is an ejection pin 6 is a sprue lock pin 7 is an ejection device 8 of a molding machine 8 is a movable core plate 9 is an ejection plate 10 is a recess 11 is an injection nozzle of a molding machine 12 is a molded product 13 is sprue and runner resin 14 is a heater

Claims (4)

In the production of resin molded products, from the nozzle that injects the molten resin, through the sprue and runner, the molten resin is filled into the molding cavity, and after the resin is solidified, the mold is opened and the molded product is taken out.
A part of the mold member that constitutes the runner space is a movable core, and the corresponding position of the movable core that faces the sprue is constituted by a sprue lock pin that operates independently from the movable core, and after filling the molding cavity with molten resin, The movable core is driven so as to narrow the runner space while the resin of the resin is kept fluid , while the sprue lock pin is not moved and remains in its original position, preparation of the resin molded article by injection molding, wherein the recess and to Rukoto resin remained. A part of the mold member that constitutes the runner space is a movable core, and the corresponding position of the movable core facing the sprue is configured by a sprue lock pin independent of the movable core, and the size of the runner space is determined from the state at the time of molten resin injection An injection mold comprising a movable core driving means for reversibly narrowing and a sprue lock holding structure that keeps a sprue lock pin in its original position when the movable core is driven . The injection mold according to claim 2, wherein the movable core is provided with a heater. The injection mold according to claim 2, wherein the movable core is provided with an ultrasonic oscillator.

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