JP4151069B2 - Ventilation mold member and injection mold having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ventilation mold member provided in an injection mold (hereinafter simply referred to as a mold) and a mold including the same.
[0002]
[Prior art]
In recent years, downsizing and thinning of IT devices such as mobile phones are progressing, and accordingly, further miniaturization and thinning of device parts and casings are required.
When manufacturing such a small and thin member by injection molding, the distance between the mold surfaces forming the cavities in the mold becomes narrow, so that the injected molten raw material is difficult to reach the entire cavity, and the cavity Since air escape from the inside tends to be insufficient, filling failure occurs, and bubbles are easily formed in the obtained molded product. Such a defect tends to occur particularly in a thin portion.
Furthermore, as a raw material used for injection molding, there is a material such as polycarbonate in which the raw material itself is thermally decomposed to generate a gas. When injection molding is performed using such a raw material, the above-described problem is more caused. It becomes easy.
[0003]
For this reason, for example, a mold material of a porous mold as shown in Patent Document 1 described later is used. Since this mold material is formed by powder sintering and fine communication holes are uniformly dispersed inside, the gas in the cavity can be exhausted out of the mold through the communication holes.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 4-72004
[Problems to be solved by the invention]
However, since this mold material is porous and has a shape in which the communication holes are dispersed, the molten raw material or mold release material filled in the cavity enters the fine communication holes from the mold surface. There was a problem that clogging occurred and exhaust performance deteriorated.
Furthermore, since the molten raw material and the release material that have entered the communication hole in this way enter deep into the fine communication hole, it is difficult to eliminate clogging even if cleaning or the like is performed.
For this reason, even when a mold using such a mold material is used to produce a smaller and thinner molded product, the gas in the cavity is insufficiently discharged and the above problem cannot be solved. Therefore, the thickness of the molded product is limited to about 0.3 mm, and it is difficult to further reduce the size and thickness of the molded product.
[0006]
In addition, when the pressure loss at the time of exhausting the gas in the cavity is large, the filling resistance of the molten raw material into the cavity is increased. And when manufacturing a small and thin member by injection molding, since the heat | fever of a molten raw material is immediately taken, fluidity | liquidity will fall easily. For this reason, conventionally, it has been necessary to use a high-speed injection molding machine having an injection speed of 300 mm / s to 2000 mm / s for injection molding of small and thin members so as not to cause defective filling. However, when performing such high-speed injection molding, air is likely to be caught in the molten raw material, and bubbles are likely to be formed in the molded product.
Further, such a high-speed injection molding machine is expensive, and the mold material is also expensive, so that the manufacturing cost of the molded product becomes high.
[0007]
This invention is made | formed in view of such a situation, Comprising: It aims at providing the metal mold | die for ventilation which improves the discharge | emission performance of the gas in a cavity, and a metal mold | die provided with the same.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, a vent mold member according to the present invention is a breathable mold member constituting a part of a mold surface forming a cavity in an injection mold,
The injection mold is provided at a connection portion between the cavity and a gas passage that leads from the cavity to the outside of the mold, and forms a mold surface in this portion, and between the cavity and the gas passage. A ventilation layer having a thickness of 0.5 mm or more and 10 mm or less allowing passage of gas; and a support member for supporting the ventilation layer from the gas passage side;
A holder member that is nested inside the vent layer with a part thereof exposed to the cavity, and the support member has a vent hole that leads from the vent layer side to the gas passage side. There are provided a plurality of inward flanges at the end of the holder member on the cavity side, and an engagement recess is formed on the end surface of the inward flange on the gas passage side. An engagement protrusion that engages with the engagement recess is formed so as to protrude sideways, and the ventilation layer engages the engagement protrusion with the engagement recess so as to move toward the cavity. It is characterized by restricted movement.
[0009]
In the vent mold member configured as described above, a part of the mold surface is configured by the vent layer. Therefore, when the molten raw material is filled in the cavity, the gas in the cavity is the vent layer and the support member. The air is exhausted out of the mold through the vent hole and the gas passage.
Here, as the ventilation layer, a porous body having fine continuous pores communicating from the mold surface side to the support member side is used, and passage of gas in the cavity is allowed by the continuous pores.
[0010]
Since the porous body is lower in strength than the same material that is not porous, when the entire mold is made of a porous body, the gold body can withstand the pressure of the molten raw material filled in the cavity. It is necessary to secure a sufficient thickness of the mold itself. Similarly, when only a part of the mold is made of a porous body, it is necessary to ensure a sufficient thickness.
On the other hand, in order for the gas in the cavity to be discharged to the outside of the mold or to the gas passage, it must move at least a distance greater than the thickness of the porous body through the fine communication hole of the porous body. As the thickness of the porous body increases, the pressure loss of the exhaust gas increases and clogging easily occurs.
[0011]
On the other hand, in the mold member for ventilation according to the present invention, since the ventilation layer is supported from the gas passage side by the support member, the ventilation layer is not crushed even if it receives the filling pressure of the molten raw material. What is necessary is just to have intensity | strength. For this reason, in the mold member for ventilation according to the present invention, the thickness of the ventilation layer can be reduced, the pressure loss of the exhaust gas through the ventilation layer is reduced, and clogging is less likely to occur. Moreover, the usage-amount of an expensive porous body can also be suppressed to the minimum.
As described above, in the venting mold member according to the present invention, since the pressure loss of the exhaust gas is small, even if the injection speed of the molten raw material is about 180 mm / s, it is difficult for filling failure to occur. In addition, since the injection speed of the molten raw material can be lowered in this way, it is possible to make it difficult to entrain air in the molten raw material, and it is difficult to form bubbles in the molded product.
Furthermore, since the air-permeable layer can be thinned in this way, even when clogging occurs, clogging can be easily eliminated by washing.
[0012]
Here, if machining is performed on the porous body, the pores on the surface are crushed and the air permeability thereof is reduced. Therefore, when machining the porous body, the discharge is more expensive than machining. Need to be processed. In addition, when cutting is performed, material loss is large, and the amount of expensive porous material used is increased. For this reason, not only when the mold itself is formed of a porous body, but also when the ventilation layer has a complicated shape, the manufacturing cost increases.
On the other hand, in the mold member for ventilation according to the present invention, the ventilation layer can be formed into a simple layer shape, so that cutting or the like is unnecessary or can be performed with a minimum of processing, and the manufacturing cost can be reduced. Can be greatly reduced.
[0013]
A mold according to the present invention has a gas passage that leads from the cavity to the outside of the mold, and the gas passage is provided with the ventilation mold member according to claim 1. A mold surface is formed at a connection portion with the gas passage.
In the mold configured as described above, the gas in the cavity is discharged well by the ventilation mold member according to claim 1.
Moreover, clogging of the air-permeable layer is difficult to occur, and when clogging occurs, clogging can be easily eliminated by washing.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a longitudinal sectional view showing a schematic configuration of a mold according to the present embodiment, FIG. 2 is a longitudinal sectional view showing a configuration of a ventilation mold member according to the present embodiment, and FIG. It is a top view which shows the structure of the support member of this mold member for ventilation | gas_flowing.
[0015]
First, an injection molding machine using a mold 1 according to the present embodiment will be described with reference to FIG. This injection molding machine has a mold clamping device (not shown) and an injection mechanism (only a nozzle is shown).
The mold clamping device is provided with a movable-side mold plate M and a fixed-side mold plate F having a flat plate shape so as to face each other, and the movable-side mold plate M faces the fixed-side mold plate F. A movable mold is mounted as a nesting on the one surface, and a fixed mold is mounted as a nesting on the one surface facing the movable mold M on the fixed mold F. Then, by moving the movable side mold plate M close to the fixed side mold plate F by the mold clamping device and bringing the surfaces facing each other into contact with each other, the mold clamping between the movable mold and the fixed mold mounted thereon is performed. As a result, a cavity that contributes to the formation of an injection molded product is formed between the movable mold and the fixed mold.
[0016]
In the example shown in FIG. 1, a sprue bush S is inserted through the fixed side template F from the other surface side to the one surface side. Further, a groove G reaching from the part facing the sprue bushing S to the part where the movable mold is mounted is formed on the one surface of the movable side mold plate M. When the mold is clamped, A runner that leads to the cavity is formed by a space formed between the fixed-side template F and one surface.
In this injection molding machine, the molten raw material is injected into the sprue bush S from the nozzle N of the injection mechanism with the mold clamped, so that the molten raw material is filled into the cavity through the sprue bush S and the runner. It has become.
[0017]
The mold 1 shown in the present embodiment includes a movable mold 2 that is mounted as a nest on the movable mold plate M in the injection molding machine configured as described above, and a movable mold 2 that is mounted as a nest on the fixed mold plate F. It has a fixed mold 3 that forms a cavity C therebetween.
At least one of the movable mold 2 and the fixed mold 3 is provided with a gas passage 4 communicating from the cavity C to the outside of the mold 1. In the present embodiment, the gas passage 4 is provided in the movable mold 2. Further, the movable side template M is formed with a through-hole H extending from the portion facing the gas passage 4 to the other surface side, thereby opening the gas passage 4 to the atmosphere.
Here, when the gas passage 4 is provided in the fixed mold 3, the through-hole H reaching from the portion facing the gas passage 4 to the other surface side is formed not in the movable mold plate M but in the fixed mold plate F. Thus, the gas passage 4 is opened to the atmosphere. In any case, the through hole H may be connected to an exhaust device such as an exhaust pump without being opened to the atmosphere.
[0018]
The movable mold 2 has a movable mold body 2a provided with a through-hole-shaped mounting port 6 for mounting a nest in a region where the cavity C is formed, and a surface facing the opposite side of the cavity C side in the movable mold body 2a. And a mounting plate 2b on which the insert in the mounting opening 6 is positioned and fixed.
The mounting plate 2b is formed with a through hole 2c that communicates from the mounting opening 6 side to a portion facing the through hole H of the movable mold plate M. The space formed by the through hole 2 c constitutes the gas passage 4.
[0019]
The venting mold member 11 according to the present embodiment is mounted as a nest in the mounting port 6, thereby forming the mold surface 1 a at the connection portion between the cavity C and the gas passage 4, and the cavity C and the gas. Gas passage between the passage 4 and the passage 4 is allowed.
The ventilation mold member 11 is a ventilation made up of a cylindrical holder member 12 mounted in the mounting opening 6 and a porous body installed in a state where a part of the holder member 12 is exposed to the cavity C. A layer 13 and a support member 14 that supports the gas-permeable layer 13 from the gas passage 4 side are provided.
The installation position of the ventilation mold member 11 in the movable mold 2 is a position where the molten raw material filled in the cavity C reaches the end (that is, in order to ensure that all the gas in the cavity C can be exhausted reliably (that is, The mold surface 1a formed by the ventilation layer 13 is set to face the final filling portion.
[0020]
The holder member 12 has a cylindrical shape having a quadrangular sectional view, and an inward flange 12a is formed at an end portion on the cavity C side. The end surface of the holder member 12 on the cavity C side constitutes a mold surface 1a, and the end surface of the inward flange 12a on the gas passage 4 side (the other end surface side) is an engagement recess 12b that engages with the ventilation layer 13. Is formed.
[0021]
The ventilation layer 13 is a flat plate-like porous body having fine continuous pores that are exposed in the cavity C and communicate from the surface that forms the mold surface 1a to the surface that is received by the support member 14, and the cavity is formed by the continuous pores. The passage of gas inside is allowed.
The pore diameter is in the range of 3 μm to 23 μm, and the porosity is in the range of 10% to 30%, for example.
Further, the thickness D of the air-permeable layer 13 is, for example, not less than 0.5 mm and not more than 10 mm.
In this embodiment, the ventilation layer 13 has an average pore diameter of about 5 μm, a porosity of 15%, and a thickness D of 2 mm.
On the outer periphery of the air-permeable layer 13, an engagement protrusion 13a that engages with the engagement recess 12b of the holder member 12 is formed to protrude laterally, and the engagement protrusion 13a is engaged with the engagement recess 12b. Therefore, the movement to the cavity C side is restricted.
In the present embodiment, the air-permeable layer 13 is formed in a rectangular shape in plan view, and an engagement protrusion 13a is provided on the short side thereof.
[0022]
In the present embodiment, the air-permeable layer 13 is composed of a porous body formed by sintering a green compact. As such a porous body, for example, a raw material powder mainly composed of low C (carbon) -low Ni (nickel) -Cr (chromium) based stainless steel powder is compacted, and the compact is vacuum-treated. Alternatively, a sintered body obtained by sintering in various atmospheric gases is further heated and nitrided in a nitrogen atmosphere at a temperature range of 800 ° C. to 1100 ° C., and PORAX (registered trademark). And porous mold materials such as Kupolex (registered trademark).
[0023]
The support member 14 has one or a plurality of vent holes 14 a that lead from the portion that receives the vent layer 13 to the gas passage 4, and allows passage of gas that has passed through the vent layer 13 to the gas passage 4 by the vent hole 14 a. However, the ventilation layer 13 is supported so as to withstand the pressure of the molten raw material filled in the cavity C.
In the present embodiment, the support member 14 has a rectangular parallelepiped shape, and a hollow portion 14b is formed on the end surface side facing the mounting plate 2b. The vent hole 14a is formed by the vent layer 13 of the support member 14 being formed. The gas is exhausted from the cavity C to the cavity portion 14b through the vent layer 13 through the vent layer 13 and flows into the gas passage 4 through the vent hole 14a of the bottom portion 14b.
[0024]
Here, the vent hole 14a is a through hole having an inner diameter of 0.5 mm to 3 mm, for example. In the present embodiment, as the vent hole 14a, 14 round holes with an inner diameter of 2 mm / cm ^{2 are} formed.
Further, as shown in FIG. 4, the vent holes 14 a are formed in a staggered manner in the plan view with respect to the support member 14.
[0025]
In the mold 1 according to the present embodiment, the molten raw material is injected into the cavity C by the injection mechanism 5 in a state where the movable mold 2 and the fixed mold 3 are clamped by the mold clamping device, as in the conventional mold. Thus, it is used for molding an injection molded product.
In this mold 1, when the molten raw material is injected into the cavity C in this way, the air in the cavity C and the gas generated by the molten raw material are vent holes 13 of the vent mold member 11 and the vent holes of the support member 14. The gas is discharged into the gas passage 4 through 14 a and is discharged out of the mold 1 through the gas passage 4, and the molten raw material is blocked by the ventilation layer 13 forming the mold surface 1 a and remains in the cavity C.
[0026]
In the venting mold member 11 according to the present embodiment, the vent layer 13 is supported from the gas passage 4 side by the support member 14, so that the vent layer 13 is not crushed even when subjected to the filling pressure of the molten raw material. As long as it has the intensity | strength of. Therefore, in the ventilation mold member 11 according to the present embodiment, the thickness D of the ventilation layer 13 can be made sufficiently thin, and the pressure loss of the exhaust gas through the ventilation layer 13 is reduced.
Further, after the gas that has passed through the ventilation layer 13 reaches the support member 14, the gas is smoothly exhausted into the gas passage 4 through the ventilation holes 14 a and the cavity portions 14 b that are larger in diameter than the continuous pores of the ventilation layer 13. The gas in the cavity C can be sufficiently and effectively discharged.
[0027]
Here, a small part of the molten raw material or the release material applied to the mold surface 1a penetrates into the continuous pores of the ventilation layer 13, but since the ventilation layer 13 is sufficiently thin, these easily penetrate the ventilation layer. 13 is discharged to the gas passage 4 and clogging is less likely to occur.
In addition, since the thickness D of the air-permeable layer 13 is thin as described above, even when clogging occurs, the clogging can be easily eliminated by cleaning.
[0028]
As described above, in the mold 1 according to the present embodiment, the pressure loss of the exhaust gas is small, and the gas in the cavity C can be discharged well, so that it is possible to manufacture a molded product that is smaller and thinner than the conventional one. It can be done well.
Further, in the mold 1 having such a high exhaust performance, filling failure is less likely to occur even when the injection speed of the molten raw material is about 180 mm / s. Such an injection speed can be realized by a generally used injection molding machine, so that it is not necessary to use an expensive high-speed injection molding machine for injection molding of small and thin parts, thereby reducing the equipment cost. be able to. In addition, since the injection speed of the molten raw material can be lowered in this way, it is possible to make it difficult to entrain air in the molten raw material, and it is difficult to form bubbles in the molded product.
[0029]
Further, in the ventilation mold member 11 according to the present embodiment, since the ventilation layer 13 is thin, the amount of expensive porous material used can be minimized. Furthermore, since the ventilation layer 13 has a simple layer shape, and processing such as electric discharge machining is not required or can be performed at the minimum, the ventilation layer 13 can be manufactured easily and at low cost.
[0030]
Here, if the pore diameter of the continuous pores formed in the ventilation layer 13 is smaller than 3 μm, the pressure loss of the exhaust gas through the ventilation layer 13 becomes large and the exhaust performance is deteriorated.
On the other hand, when the pore diameter is larger than 23 μm, the molten raw material and the release agent are likely to enter the continuous pores, and clogging is likely to occur. For this reason, the pore diameter is preferably in the range of 3 μm to 23 μm.
Similarly, if the porosity of the ventilation layer 13 is lower than 10%, the pressure loss of the exhaust gas through the ventilation layer 13 becomes large and the exhaust performance is deteriorated. On the other hand, if the porosity is higher than 30%, the molten raw material easily enters the pores. For this reason, it is preferable that the porosity of the ventilation layer 13 be in the range of 10% to 30%.
On the other hand, if the thickness D of the ventilation layer 13 is smaller than 0.5 mm, the strength of the ventilation layer 13 becomes insufficient. On the other hand, when the thickness D is larger than 10 mm, the pressure loss of the exhaust gas through the ventilation layer 13 becomes large and the exhaust performance is deteriorated. For this reason, it is preferable that the thickness D of the ventilation layer 13 be 0.5 mm or more and 10 mm or less.
[0031]
【The invention's effect】
As described above, in the mold using the ventilation mold member according to the present invention, the pressure loss when exhausting the gas in the cavity can be reduced and the exhaust performance can be improved. Thin parts can be molded well.
Moreover, since a small and thin part can be favorably molded without using a high-speed injection molding machine, the equipment cost can be reduced.
In addition, since the thickness of the air-permeable layer can be reduced, clogging is less likely to occur, and even when clogging occurs, clogging can be easily eliminated by washing.
Furthermore, since the ventilation layer can have a simple layer shape, the ventilation layer can be manufactured easily and at low cost.
In addition, since the injection speed of the molten raw material can be lowered in this way, it is possible to make it difficult to entrain air in the molten raw material, and it is difficult to form bubbles in the molded product.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of a mold according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a configuration of a venting mold member according to the present embodiment.
FIG. 3 is a plan view showing a configuration of a support member of a ventilation mold member according to the present embodiment.
[Explanation of symbols]
1 Mold 1a Mold surface 4 Gas passage 11 Breathable mold member 12 Holder member 12a Inward flange 12b Engaging recess 13 Venting layer 13a Engaging protrusion 14 Support member 14a Venting hole C Cavity

Claims (2)

A breathable mold member constituting a part of a mold surface forming a cavity in an injection mold,
The injection mold is provided at a connection portion between the cavity and a gas passage that leads from the cavity to the outside of the mold, and forms a mold surface in this portion, and between the cavity and the gas passage. A ventilation layer having a thickness of 0.5 mm or more and 10 mm or less allowing passage of gas;
A support member for supporting the ventilation layer from the gas passage side;
A holder member installed as a nesting inside the ventilation layer with a part exposed in the cavity,
The support member is provided with a plurality of ventilation holes that communicate from the ventilation layer side to the gas passage side, and an inward flange is formed at an end of the holder member on the cavity side, and the gas of the inward flange is formed. An engagement recess is formed on the end face on the passage side, and an engagement protrusion that engages with the engagement recess is formed on the outer periphery of the ventilation layer so as to protrude laterally. The vent mold member is characterized in that the movement toward the cavity is restricted by engaging the engagement protrusion with the engagement recess. It has a gas passage that leads from the cavity to the outside of the mold,
The ventilation mold member according to claim 1 is provided at a connection portion between the cavity and the gas passage, and a mold surface at the connection portion between the cavity and the gas passage is configured by the ventilation mold member. An injection mold characterized by being made.

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