JPH0813408B2 - Injection mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an injection mold, and in particular, a molten metal is distributed and supplied to a plurality of cavities to form a plurality of products at the same time.
The present invention relates to an injection mold suitable for die casting, low pressure casting, plastic molding and the like.

[Conventional technology]

There is an injection molding method described in Japanese Examined Patent Publication No. 1-40707, which is known as so-called multi-cavity mold casting, in which a molten metal is distributed and supplied to a plurality of cavities and a plurality of products are simultaneously molded. This injection molding method is a distributor having a plurality of distribution grooves dedicated to each cavity at the molten metal inlet portion of the injection sleeve,
That is, by arranging the spool core and pressurizing the molten metal in the injection sleeve by the movement of the injection plunger, the molten metal is distributed and supplied from the molten metal inlet portion to the plurality of cavities through the plurality of distribution grooves and the plurality of runners dedicated to each cavity, Multiple products are molded at the same time. In addition, in Japanese Examined Patent Publication No. 1-40707, the runner has a shape that spreads toward the downstream side.

[Problems to be Solved by the Invention]

However, in the above-mentioned prior art, the optimum shape of the molten metal passage from the molten metal inlet portion including each distribution groove to each runner is not considered, and there are the following problems.

That is, in the above-mentioned conventional technique, when the molten metal passage from the molten metal inlet portion including each distribution groove to each runner is viewed in a section including the axis of the injection sleeve and each distribution groove and the center line of the runner, the molten metal flow in the distribution groove is prevented. It is formed so that the direction changes greatly by 90 ° or more. For this reason, at the location where the direction of the molten metal flow changes greatly, the molten metal is concentrated on the outer diameter side due to the principle of centrifugal casting to form a void on the inner diameter side, where air is accumulated and the inside and outside of the direction change portion of the molten metal flow are formed. Disturbance of the melt front occurs due to the difference in molten metal flow speed. In particular, in the above-mentioned prior art, since the runner has a shape that spreads toward the downstream side, the cross-sectional area of the molten metal passage becomes larger as it goes to the downstream side, and the generation of voids on the inner diameter side of the direction change portion of the molten metal flow becomes remarkable.

By the way, in a multi-cavity injection molding die in which the molten metal is distributed and supplied to a plurality of cavities and a plurality of products are simultaneously molded, the projected area S of the molten metal passage with respect to the main dividing surface of the mold becomes large unlike the case of the single cavity molding. Therefore, the injection pressure P of the molten metal
Is restricted so that the mold opening force F1 is less than the mold clamping force F2 of the molding machine. That is, P × S = F1 <F2 and P <F2 / S must be satisfied, and the molten metal injection pressure P cannot be increased. If the injection pressure P cannot be increased in this way, the air once accumulated as described above will be caught in the molten metal at the runner portion without being crushed by the pressure, and will remain as cast holes (diameter 0.25 mm or more) in the cast product. Reduce quality.

Further, in the above-mentioned conventional technique, the direction of the molten metal flow in the distribution groove is
Because the molten metal passage lengthens because of the large change of 90 ° or more, and each runner has a shape that widens toward the downstream side, 1
There is also a problem that it is uneconomical because the amount of molten metal used for casting individual products is large.

Further, when the casting is taken out of the mold after the solidification of the molten metal, the biscuit formed by solidifying the molten metal at the molten metal inlet part is grasped by a claw of a robot or the like. Since the center of the direction changing part is located on the reflective sleeve side from the main dividing surface of the mold, it is difficult to make the biscuit project sufficiently from the product part, and the claw of a robot or the like that grips the biscuit hits the product part and is difficult to remove. There was a problem.

An object of the present invention is to improve the shape of the molten metal passage leading to each runner portion to reduce the amount of air taken into the molten metal in the runner portion, reduce the occurrence of defects and save the amount of molten metal used. It is to provide an injection mold of.

Another object of the present invention is to provide a multi-cavity injection molding die capable of easily taking out a casting from a die using a robot or the like.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a plurality of runners between the inlet recess of the spool core and the plurality of runners dedicated to each cavity, which are arranged to face the molten metal inlet of the injection sleeve. A plurality of distribution grooves dedicated to each cavity are provided, and pressure is applied to the molten metal in the injection sleeve by using a pressurizing means such as an injection plunger. In an injection molding die for simultaneously supplying a plurality of cavities via a runner and molding a plurality of products at the same time, the inlet recess of the spool core, each distribution groove, and a runner are connected to the axis of the injection spool and each distribution groove. When viewed in a cross section including the center line of the runner, the center line of the molten metal passage formed by the inlet recesses of the spool core, the distribution grooves, and the runner is injected from the main dividing surface of the mold. With turning angle located on the side melt flow is less than 90 °, the cross-sectional area of the molten metal passage is obtained by forming so as to be smaller as it goes downstream.

The “division surface of the mold” refers to the division surface where the molding gate opening to the cavity is located.

Preferably, each of the distribution grooves comprises a plurality of cuts provided only at the tip of the injection sleeve. It should be noted that each of the distribution grooves may be constituted by a plurality of notches provided on both the tip of the injection sleeve and the spool core arranged facing the molten metal inlet of the injection sleeve. It may be configured by a plurality of notches provided only in the core.

[Action]

In the injection molding die of the present invention configured as described above, the inlet recesses of the spool core, the respective distribution grooves and the runner are arranged such that the center line of the melt passage is located closer to the injection sleeve than the main dividing surface of the mold and By forming the turning angle to be 90 ° or less, the concentration of the molten metal on the outer diameter side caused by the principle of centrifugal casting at the molten metal flow turning portion is suppressed,
The occurrence of voids on the inner diameter side is reduced and the disturbance of the melt flow front surface (melt front) is also reduced. Further, by making the cross-sectional area of the molten metal passage small as it goes downstream, the pressure increases as the molten metal goes downstream, so that even if the injection pressure P is limited, it will be appropriate in the molten metal passage. The pressure can be secured. For this reason,
Even if voids are generated as described above, the air itself that has accumulated in the voids is also crushed and becomes smaller, so the amount of air that is trapped in the molten metal in the runner is reduced, and a good quality cast product with no porosity is obtained. Obtainable.

In addition, since the turning angle of the molten metal flow is 90 ° or less, the length of the molten metal passage is short and the cross-sectional area of the molten metal passage becomes smaller as it goes to the downstream side. Therefore, the amount of molten metal used to cast one product Can be reduced.

Further, when viewed in a cross section including the axis of the injection sleeve and the centerlines of the distribution grooves and the runner, the centerline of the molten metal passage is formed so as to be located on the injection sleeve side with respect to the main dividing surface of the mold. The biscuit formed by the molten metal inlet part can be sufficiently projected from the product part as compared with the conventional case, and the biscuit can be grasped with a claw of a robot or the like and the cast product can be easily taken out from the mold.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7 in the case of a two-die mold used in a horizontal die casting apparatus.

The molding die of this embodiment has a fixed die 1 and a movable die 2 as shown in FIGS. 1 to 5, and the fixed die 1 includes a die body 1a, a fixed die insert 3 and an injection sleeve 5. The movable die 2 is incorporated into the die body 2a, the movable die insert 4 and the spool core 6 are incorporated in the movable die 2.
Is built in. A plunger 7 is slidably fitted in the injection sleeve 5, and the tip of the injection sleeve 5 abuts on the spool core 6, and a molten metal inlet portion 8 is provided between the tip portion of the injection sleeve 5 and the spool core 6. Is forming.

An inlet recess 9 is formed on the end surface of the spool core 6,
At the tip of the injection sleeve 5, as shown in FIG.
Three independent distribution grooves 10, 11 are formed. Further, the fixed mold insert 3 and the movable mold insert 4 forming the main dividing surface of the molding die, that is, the main dividing surfaces 3a and 4a, respectively,
Two runners 12 and 13 that are separated from each other and two runners that are connected to these runners via gates 14 and 15 and that are separated from each other on the left and right
Two product cavities 16, 17 are formed. Distribution groove 10,
One end of 11 is connected to the molten metal inlet 8 through the recess 9 of the spool core 6, and the other end is connected to the corresponding runner 12, 13.
Are connected to each other. That is, the runners 12 and 13 are dedicated runners for the cavities 16 and 17, and the distribution grooves 10 and 11 dedicated to the cavities 16 and 17 are provided corresponding to the runners 12 and 13.

The end surface of the tip of the injection sleeve 5 coincides with the main dividing surfaces 3a, 4a as shown in FIGS. 1 and 5, and the distribution grooves 10, 11
Is formed by forming a notch in the tip portion of the injection sleeve 5 as described above. Further, the inlet recess 9 of the spool core 6, the distribution grooves 10, 11 and the runners 12, 13
In the closed state where the fixed die 1 and the movable die 2 are in contact with each other, the molten metal passage formed by them is gradually narrowed as seen in the cross section of FIG. 1, and the distribution grooves 10 and 11 and the runner 1 are formed.
As shown in Fig. 3, reference numerals 2 and 13 extend in a constant width. As a result, the inlet recess 9 of the spool core 6 and the distribution grooves 10 and 11
The runners 12 and 13 are in a closed state in which the fixed mold 1 and the movable mold 2 are in contact with each other, and the axis of the injection sleeve 5 and the distribution grooves 10 and 11 are formed.
And a cross section including the center lines of the runners 12 and 13, that is, the cross section shown in FIG. 1, the molten metal formed by the inlet recess 9 of the spool core 6, the distribution grooves 10 and 11 and the runners 12 and 13. The center line of the passage is located closer to the injection sleeve 5 than the main dividing surfaces 3a, 4a of the mold, and the direction of the molten metal flow from the molten metal inlet portion 8 to the respective runners 12 and 13 via the distribution grooves 10 and 11 is changed. It is formed to be 90 ° or less. Further, the inlet recess 9 of the spool core 6, the distribution grooves 10 and 11 and the runners 12 and 13 are formed so that the cross-sectional area of the molten metal passage formed by them becomes smaller as it goes downstream. .

The fixed die 1 and the movable die 2 are opened and closed by moving the movable die 2 left and right in FIGS. 1 and 5 by a hydraulic mechanism (not shown).

The casting formed by solidifying the molten metal filled in the die under pressure remains on the movable die 2 side when the die is opened, and the extrusion plate 18 shown in FIGS. 1 and 5 is not shown in the figure after the die is opened. Is moved in the right direction in the drawing by the holder 19 to be extruded through a plurality of extruding pins 20 fixed to the extruding plate 18.

Next, the method of use and the operation of the mold described above will be described.

Molten metal is injected into the injection sleeve 5 from the holding furnace using a ladle and the plunger 7 is moved from right to left in FIGS. 1 and 5, so that the molten metal in the injection sleeve 5 is melted into the molten metal inlet portion 8 and the sprue core 6. From the inlet recess 9 of the injection sleeve 5 through the distribution grooves 10 and 11 and the runners 12 and 13 into the product cavities 16 and 17 from the gates 14 and 15 under pressure, two products are simultaneously molded. In the above molding process, the molten metal is distributed from the inlet recess 9 of the spool core 6 having a sufficiently high molten metal temperature to the distribution grooves 10 and 11 dedicated to the respective cavities 16 and 17.
Runner 12,1 dedicated to each cavity 16,17
3, because it is distributed and supplied to the gates 14 and 15 and the product cavities 16 and 17, the distributability is excellent, and variations in the molten metal supply balance to the product cavities for each casting shot are reduced. Further, in this embodiment, the distribution grooves 10, 1 of the injection sleeve 5 are
1, runners 12,13, gates 14,15 and product cavities 16,1
Since all 7 have a symmetrical shape and arrangement,
The product cavities 14 and 15 are filled with the molten metal under the same conditions. Therefore, the quality of the products obtained in the cavities 16 and 17 can be made uniform.

Further, when the turning angle of the molten metal flow from the molten metal inlet portion to each runner through each distribution groove is 90 ° or more as in the conventional technique described in Japanese Patent Publication No. 1-40707, As shown in FIG. 9 and FIG. 10, at the molten metal flow direction changing portion of the molten metal passage from the molten metal inlet portion 8 including the distribution grooves 50, 51 to the respective runners 52, 53, the centrifugal force is applied to the outer diameter side. The molten metal is concentrated and a void 54 is formed on the inner diameter side, and air is accumulated there, and due to the difference in the molten metal flow velocity between the inner diameter side and the outer diameter side of the direction change portion of the molten metal flow, the molten metal flow front surface, that is, the melt front
55 disturbances occur. In particular, in the above-mentioned conventional technique, since the runner has a shape that spreads toward the downstream side, the cross-sectional area of the molten metal passage becomes larger as it goes to the downstream side, and the generation of voids on the inner diameter side of the direction change portion of the molten metal flow becomes remarkable. .

By the way, in a multi-cavity injection molding die, unlike the case of single-cavity molding, the projected area S of the molten metal passage with respect to the main dividing surface of the die is large, so the molten metal injection pressure P is the mold opening force F1 There is a limit to keep the mold clamping force below F2. That is, P × S = F1 <F2 and P <F2 / S must be satisfied, and the molten metal injection pressure P cannot be increased. For this reason, the air once accumulated as described above is not crushed by the pressure and is entrained in the molten metal at the runner portion, and remains in the cast product as a cavity (diameter of 0.25 mm or more) to deteriorate the quality of the cast product. Further, the length of the molten metal passage from the molten metal inlet portion 8 to the runners 52, 53 is long, and the amount of molten metal used for casting one product is large, which is uneconomical.

On the other hand, in the present embodiment, the inlet recess 9 of the spool core 6, the distribution grooves 10 and 11 and the runners 12 and 13 are formed by the molten metal flow direction change angles as described above.
Since it is formed to be 90 ° or less, the concentration of molten metal on the outer diameter side caused by the principle of centrifugal casting at the direction of the molten metal flow direction is suppressed, and the difference in molten metal flow velocity between the outer diameter side and the inner diameter side is small. Distortion of the melt front 21 also becomes small. Further, since the cross-sectional area of the molten metal passage is formed so as to become smaller as it goes downstream, the pressure increases as the molten metal goes downstream, and the injection pressure P of the molten metal is limited due to the multi-cavity production. However, it is possible to secure an appropriate pressure in the molten metal passage. For this reason, not only the generation of voids as described above is reduced, but also the air itself accumulated in the voids is crushed and reduced, so that the amount of air taken into the molten metal in the runners 12 and 13 is reduced, and the porosity is reduced. It is possible to obtain a good quality cast product. Further, the length of the molten metal passage becomes shorter and the cross-sectional area of the molten metal passage becomes smaller toward the downstream side, so that the amount of molten metal used per cast product is also reduced.

Furthermore, when the casting is taken out of the mold after the solidification of the molten metal, the biscuit formed by solidifying the molten metal at the molten metal inlet part is gripped with a claw such as a robot, but the direction change angle of the molten metal flow is 90 ° or more. In the above-mentioned related art, as shown in FIGS. 9 to 11, the center of the molten metal flow direction changing portion in the distribution grooves 50, 51 is located on the opposite side of the injection sleeve 57 from the main dividing surface 56 of the mold. Therefore, at the extrusion completion position of the plunger 58 shown in FIG. 11, the biscuit 59 formed by solidifying the molten metal at the molten metal inlet portion can be sufficiently projected from the product portion 60 as shown in FIG. 12 (B). Therefore, the insertable range of the take-out robot claw becomes smaller. Therefore, the claw of the robot that holds the biscuit 59 hits the product portion, making it difficult to take out the casting.

On the other hand, in this embodiment, the centers of the distribution grooves 10 and 11 as seen in a cross section including the axis of the injection sleeve 5 are formed so as to be located closer to the injection sleeve 5 than the main dividing surfaces 3a and 4a. As shown in FIG. 12 (A), the molten metal inlet portion 8 of the casting
The biscuit 22 formed by can be sufficiently protruded from the product part 23 compared with the conventional one, and the insertable range of the take-out robot's claw is increased, and the biscuit 22 is grasped by using the claw of the robot and the casting is taken out. It will be easy. Therefore, it becomes possible to fully automate the injection molding including the removal of the casting.

Another embodiment of the present invention will be described with reference to FIGS. 13 and 14. This embodiment shows a modification of the distribution groove. In the drawing, the same members as those shown in FIGS. 1 to 8 are designated by the same reference numerals.

In FIG. 13, the distribution grooves 10A and 11A of this embodiment are formed by providing two notches on both the tip of the injection sleeve 5A and the spool core 6A. Also in the embodiment shown in FIG. 14, the distribution grooves 10B and 11B are formed by providing two notches in both the spool core 6B and the spool core 6B.

And in the embodiment shown in FIG. 13, the depth of cut l ₂ provided at the tip of the injection sleeve 5A is larger than the depth of cut l ₁ provided in the spool core 6A (l ₂ > l ₁ ). Therefore, also in this embodiment, in the closed state where the fixed mold 1 and the movable mold 2 are in contact with each other, a cross section including the axis of the injection sleeve 5A and the center lines of the distribution grooves 10 and 11 and the runners 12 and 13,
That is, as seen in the cross section shown in FIG. 13, the center line of the molten metal passage is located closer to the injection sleeve 5A side than the main dividing surfaces 3a, 4a, and the runner 12A from the molten metal inlet portion 8 via the distribution grooves 10A, 11A. The turning angle of the molten metal flow up to 13A is less than 90 °. The other structure is the same as that of the first embodiment shown in FIGS.

Further, in the embodiment shown in FIG. 14, the depth of cut l ₂ provided at the tip of the injection sleeve 5B is smaller than the depth of cut l ₁ provided in the spool core 6B (l ₂ <l ₁ ) However, the tip end position of the injection sleeve 5B is displaced to the right in the figure from the main dividing surfaces 3a and 4a. As a result, also in this embodiment, the center line of the molten metal passage seen in a similar cross section is the main dividing surface 3
It is located closer to the injection sleeve 5B than a, 4a, and the turning angle of the molten metal flow from the molten metal inlet portion 8 to each runner 12B, 13B via each distribution groove 10B, 11B is 90 ° or less. The other structure is the same as that of the first embodiment shown in FIGS.

Therefore, also in the embodiment shown in FIGS. 13 and 14, the same effect as that of the first embodiment can be obtained.

Further, if the idea of the embodiment shown in FIG. 14 is further developed, even if two notches are provided only in the spool core 6, the distribution groove whose center is located closer to the injection sleeve than the main dividing surface is. It is possible to form the same, and also by this, the angle between the direction points of the molten metal flow is 90 ° or less, and the same effect can be obtained.

In the above embodiment, the product cavities 16 and 17 have a symmetrical shape and arrangement as shown in FIGS. 3 and 4, but may have an asymmetrical shape and arrangement.
In this case, distribution grooves 10, 11, runners 12, 13 and gate 1
By appropriately carrying the cross-sectional area of the molten metal passage and its direction to 4, 15, it is possible to make the molten metal filling conditions for each product cavity the same, and to obtain a uniform product of the same quality as in the above embodiment. .

Further, although the above-mentioned embodiment has described the mold of the horizontal molding apparatus, the present invention can be similarly applied to the molds of the vertical mold and the oblique molding machine.

〔The invention's effect〕

According to the present invention, the amount of air taken into the molten metal in the runner portion is reduced, a good quality cast product can be obtained, the molten metal passage length becomes short, and the molten metal passage cross-sectional area becomes smaller as it goes downstream. Therefore, the amount of molten metal used per cast product can be saved. Therefore, a plurality of good quality cast products can be obtained with the minimum amount of molten metal.

Further, the biscuit formed by the molten metal inlet of the casting can be sufficiently projected from the conventional product, and the biscuit can be easily grasped from the mold by using the claws of a robot or the like. . Therefore, full automation of injection molding becomes easy.

[Brief description of drawings]

FIG. 1 is a sectional view of an injection mold according to an embodiment of the present invention taken along the line I-I of FIG. 2 (B), and FIGS. 2 (A) and 2 (B) respectively show the injection mold. FIG. 3 is a front view and a side view, FIG. 3 is a front view of a fixed type seen from line III-III in FIG. 2 (A), and FIG. 4 is IV-IV in FIG. 2 (A).
FIG. 5 is a front view of the movable mold seen from the line, FIG. 5 is a cross-sectional view taken along the line VV of FIG. 2 (B), FIG. 6 is a perspective view showing the tip of the injection sleeve, and FIG. And FIG. 8 are sectional views similar to FIG. 1 showing different filling processes of the molten metal, and FIGS. 9 to 11 are FIG. 1 showing different filling processes of the molten metal in the conventional injection mold. 7 and 8
12 (A) is a cross-sectional view corresponding to the drawing, FIG. 12 (A) is a view for explaining the ease of taking out a cast product molded according to this embodiment by a robot, and FIG. 12 (B) is a conventional view. FIG. 13 is a similar view for explaining the difficulty of taking out a cast product molded by an injection mold by a robot, and FIGS. 13 and 14 respectively show an injection mold according to another embodiment of the present invention. FIG. Explanation of symbols 1 …… Fixed type 2 …… Movable type 3a, 4a …… Main split surface 5 …… Injection sleeve 6 …… Spool core 7 …… Plunger 8 …… Melting inlet 10,11 …… Distribution groove 12, 13 …… Runner 16,17 …… Cavity

Claims (4)

[Claims] 1. A plurality of exclusive use for each cavity corresponding to a plurality of runners between a plurality of runners dedicated to each cavity and an inlet recess of a spool core which is arranged to face a molten metal inlet of an injection sleeve. Distribution groove is provided and pressure is applied to the molten metal in the injection sleeve by using a pressure means such as an injection plunger, so that a plurality of distribution grooves dedicated to each cavity and a plurality of runners are provided from the molten metal inlet portion. In an injection molding die that dispenses and supplies a plurality of products to a cavity at the same time, the inlet recess of the spool core, the distribution grooves and the runners are aligned with the axis of the injection sleeve and the center lines of the distribution grooves and the runners. When viewed in a cross-section including the above, the center line of the molten metal passage formed by the inlet recesses of the spool core, the distribution grooves and the runner is located closer to the injection sleeve than the main dividing surface of the mold, and An injection molding die, characterized in that the turning angle becomes 90 ° or less and the cross-sectional area of the molten metal passage becomes smaller as it goes downstream. 2. The injection molding die according to claim 1, wherein each of the distribution grooves comprises a plurality of cuts provided only at the tip of the injection sleeve. 3. The injection molding die according to claim 1, wherein each of the distribution grooves is provided in both a tip of the injection sleeve and a spool core arranged so as to face a molten metal inlet portion of the injection sleeve. An injection mold characterized by comprising a plurality of cuts. 4. The injection molding die according to claim 1, wherein each of the distribution grooves comprises a plurality of notches provided only in a spool core arranged facing the molten metal inlet portion of the injection sleeve. And injection mold.