Molding mold, injection molding device, and manufacturing method of resin molded product

Abstract

To obtain a molding mold made of a material other than metal, which is more durable than conventional molding mold made of resin.SOLUTION: A molding mold includes: a first mold having a first molding surface; and a second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting part. When the first mold and the second mold are clamped together, a runner is defined by the runner surface, a cavity is defined by the first molding surface and the second molding surface, and a material constituting at least a portion of the first mold and the second mold contains one of resin, ceramic, and glass as a main component, and when a shortest distance between the connecting part and the first molding surface is T [mm] and an inner diameter of the connecting part is Dm [mm], a relationship T [mm]<Dm [mm] is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molding die, an injection molding device, a method for manufacturing a resin molded product, and the like. [Background technology]

[0002] In injection molding, resin molded products are generally produced by injecting molten resin at high temperatures of 200-300°C into the cavity of a mold, but because the resin needs to be filled at high speed and pressure, metal materials with sufficient strength are often used for the mold. Molds made from metal, or metal dies, generally tend to be heavy.

[0003] However, with the recent trend toward a diversified range of products, it may become necessary to manufacture a wide variety of resin molded products in small lots with a daily production volume of, for example, 100 or less units. In such cases, it is necessary to change the molds of the injection molding machine every time the type of resin molded product being manufactured changes.

[0004] However, metals such as stainless steel are not easy to process, so it can take a long time to make metal molds. Also, because metal molds are heavy, when producing a wide variety of products in small lots, the workload and time required for mold replacement (so-called changeover) increases, resulting in a problem of reduced production efficiency.

[0005] Patent Document 1 describes a method for manufacturing plastic gears by injection molding using a plastic mold. Plastic molds can be made relatively easily by, for example, 3D printing or machining, and have the advantage of being able to be made more quickly than metal molds. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-130935 Summary of the Invention

Problems to be Solved by the Invention

[0007] Since resin is a lighter material than metal, there is a possibility of reducing the weight of the mold. However, since the strength of the material is not necessarily higher than that of metal, when injecting high-temperature molten resin into the cavity, problems such as cracking and plastic deformation are likely to occur. In particular, such damage is likely to occur at the part where the molten resin injected from the gate first collides within the cavity. If the durability of the mold is low, it may be necessary to frequently replace the mold with a new one to ensure the shape accuracy of the resin molded product, which may result in a decrease in the productivity of the resin molded product.

[0008] Therefore, there has been a demand for a mold using a material different from metal and having better durability than conventional resin molds.

Means for Solving the Problems

[0009] The first aspect of the present invention includes a first mold having a first molding surface, and a second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion. When the first mold and the second mold are clamped, a runner is defined by the runner surface, and a cavity is defined by the first molding surface and the second molding surface. The material constituting at least a part of the first mold and the second mold includes, as a main component, any one of resin, ceramic, and glass. When the shortest distance between the connecting portion and the first molding surface is T [mm] and the inner diameter of the connecting portion is Dm [mm], the relationship T [mm] < Dm [mm] is satisfied. It is a mold characterized by this.

[0010] The second aspect of the present invention includes a first mold having a first molding surface, and a second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion, and is characterized in that it is composed of a material in which 50% by volume or more is mainly composed of polyimide resin.

Effects of the Invention

[0011] According to the present invention, it is possible to provide a molding die that is made of a material other than metal and that has superior durability compared to conventional molding dies made of resin. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view of an injection molding apparatus according to an embodiment. [Figure 2] 1A is an external view of a molded product with a runner molded by the injection molding apparatus according to the embodiment, as seen obliquely from above, and FIG. 1B is an external view of the molded product with a runner, as seen obliquely from below. [Figure 3] 1 is a cross-sectional view of a molded product with a runner cut along a line passing through the solidified runner. [Figure 4] 1A is a perspective view of a molded product with a runner according to a modification of the embodiment, as seen from above at an angle; FIG. 1B is a cross-sectional view of the molded product with a runner according to the modification, taken along a line passing through the solidified runner; DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes a molding die, an injection molding apparatus, a method for manufacturing a resin molded product, and the like according to embodiments of the present invention with reference to the drawings. The embodiments shown below are merely examples, and those skilled in the art can appropriately modify and implement the detailed configurations within the scope of the present invention without departing from the spirit and scope of the present invention.

[0014] In the drawings referred to in the following description of the embodiments and examples, elements denoted by the same reference numerals have the same functions unless otherwise specified. When a plurality of identical elements are arranged in a drawing, the reference numerals and their descriptions may be omitted.

[0015] In addition, because the drawings may be represented schematically for the convenience of illustration and explanation, the shape, size, and arrangement of elements depicted in the drawings may not strictly correspond to the actual objects. Furthermore, the descriptions "XX or more and YY or less" and "XX to YY" that represent a numerical range mean a numerical range including the endpoints XX (lower limit) and YY (upper limit), unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0016] [Outline of the embodiment] In the embodiment described below, at least a part of the mold is provided with a portion formed of a material containing one of resin, ceramic, or glass as a main component. In this specification, the term "main component" refers to the component that is the largest in weight when the component is made up of multiple components (materials), and in this specification, this means that the component in question accounts for 50% by weight or more.

[0017] The mold includes a first mold and a second mold, and the first mold and the second mold can be clamped together. One of the first mold and the second mold (e.g., the first mold) can be a movable mold, and the other (e.g., the second mold) can be a fixed mold. At least a portion of each of the first mold and the second mold that make up the mold includes a molding piece that has a molding surface and defines a cavity when the molds are clamped. The molding surface is the surface of the molding piece that becomes the inner wall of the cavity. At least one of the first mold and the second mold that make up the mold can also be composed of multiple molding pieces. At least one of the multiple molding pieces can have a portion formed of a material containing resin, ceramic, or glass as its main component. The molding piece in the second mold can have a runner, which is a channel for injecting molten resin into the cavity, and a gate, which connects the runner and the cavity. The molten resin injected into the runner is injected into the cavity through the gate. In a molding die (molding piece), the surface that defines the cavity is called the molding surface, and the surface that defines the runner is called the runner surface. At a gate, which is the connecting portion between the runner and the cavity, the runner surface and the molding surface are connected by a connecting portion. The gate can be a portion surrounded by the connecting portion between the runner surface and the molding surface. The molding die includes a portion facing the gate, which is the connecting portion between the runner and the cavity, and a portion facing the connecting portion between the runner surface and the molding surface. The portion facing the connecting portion between the runner surface and the molding surface surrounds the portion facing the gate, which is the connecting portion between the runner and the cavity. In a molding die, the portion facing the connecting portion between the runner surface and the molding surface and the portion facing the gate, which is the connecting portion between the runner and the cavity, are called opposing portions. The opposing portion in a molding die includes a portion of the molding surface and its vicinity (inside the molding die). Of the opposing portions in a molding die, a portion of the molding surface is called the opposing region. The runner may be either a cold runner or a hot runner, but this embodiment is suitable for use with a cold runner. When a hot runner is used, a valve pin for closing the gate can be disposed inside the runner.

[0018] Molds made from materials primarily composed of resin, ceramic, or glass can be produced using processing techniques such as cutting, polishing, molding, 3D printing, and coating. Examples of resins that can be used include polyimide resin, epoxy resin, acrylic resin, silicone resin, and fluororesin. A mold made of 50% or more by volume of resin is called a resin mold. Examples of ceramics that can be used include silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, aluminum nitride, and silicon carbide. A mold made of 50% or more by volume of ceramic is called a ceramic mold. Examples of glass that can be used include silicate glass, borosilicate glass, quartz glass, soda-lime glass, and lead glass. A mold made of 50% or more by volume of glass is called a glass mold. For simplicity, materials primarily composed of resin, ceramic, or glass are referred to as non-metallic materials.

[0019] In one embodiment, a material containing resin, ceramic, or glass as a main component and having a density of 5.0 [g / cm 3 At least a part of the mold is made of a low-density material having a density smaller than 7.9 [g / cm 3 ], thereby realizing a mold that is lighter than a metal mold. SUS, which has been commonly used as a metal material for molds, has a density of 7.9 [g / cm 3 ]. 3 ]. It can be said that metals used for molding dies, including SUS, are materials with a relatively high density. In order to make the molding die lighter than conventional molding dies (metal dies) that use such metals, low-density materials can be used. In order to make the molding die lighter, the volume of the low-density material in the molding die is preferably 25% by volume or more, more preferably 50% by volume or more, and may be 75% by volume or more. In one embodiment, the molding die contains one of resin, ceramic, and glass as a main component and has a density of 3.5 [g / cm 3 ] or less, and further, materials with a density of 3.0 [g / cm 3 ] or less may also be used.

[0020] In one embodiment, a mold using a material containing any one of resin, ceramic, and glass as a main component is configured such that the shape of the runner and the shape of the cavity satisfy a predetermined relationship in order to ensure the required durability. When the shortest distance between the gate, which is the connecting portion between the runner and the cavity, and the portion (opposing portion) of the mold facing the gate is T [mm] and the inner diameter of the gate is Dm [mm], the mold is configured to satisfy the relationship of T [mm] < Dm [mm]. The ratio Dm / T of Dm [mm] to the distance T [mm] is preferably 1.1 or more, and may be 1.5 or more, may be 2.0 or more, may be 4.0 or less, or may be 3.0 or less.

[0021] In the mold, the portion that is easily damaged is the portion where the molten resin injected from the gate into the cavity directly collides. That is, the opposing portion of the mold facing the gate is easily damaged. If the flow rate of the colliding molten resin is large, cracks or plastic deformation may occur in this opposing portion, resulting in a decrease in practical durability. In this embodiment, in a mold made of a material containing any one of resin, ceramic, and glass as a main component, the durability of the mold is improved by suppressing the speed of the molten resin colliding with the portion where damage is likely to occur. For example, when watering with a hose, it can be understood that if the outlet diameter of the hose is narrowed, the initial velocity of the water ejected from the hose increases, and if the outlet diameter is increased, the initial velocity of the ejected water decreases. In the embodiment, by configuring the mold so as to satisfy the relationship of T [mm] < Dm [mm], the opening diameter of the gate is made sufficiently large, and the speed at which the molten resin ejected from the gate collides with the molding surface facing the gate across the cavity space can be suppressed.

[0022] It is suitable when the portion where damage is likely to occur is made of a material containing as a main component any one of resin, ceramic, and glass, which are materials where damage is more likely to occur than metal. In particular, it is suitable when the range within a distance D [mm] equal to Dm [mm] from the connecting portion includes a portion made of a material containing as a main component any one of resin, ceramic, and glass. The range of the distance T [mm] from the connecting portion becomes the opposing region. The range within a distance D [mm] from the connecting portion is the range of (D - T) [mm] from the opposing region into the interior of the mold. If the opposing region is made of a material containing as a main component any one of resin, ceramic, and glass, the portion at a distance T [mm] from the connecting portion will be made of a material containing as a main component any one of resin, ceramic, and glass. Note that the opposing region, which is the molding surface in the opposing portion, may be made of a non-metallic material and a metallic material may be used for its base. Also, the opposing region, which is the molding surface in the opposing portion, may be made of a metallic material and a non-metallic material may be used for its base. The metallic material provided on the molding surface in this case can function as a protective layer. The opposing region may be made of a metallic material, its base may be made of a non-metallic material, and further its base may be made of a metallic material. In any case, damage to the non-metallic material within the range of a distance D [mm] from the connecting portion is suppressed.

[0023] Also, in one embodiment, when the minimum diameter of the runner is Dmin [mm], the runner and the cavity are configured to satisfy the relationship of T [mm] < Dmin [mm]. By satisfying the relationship of T [mm] < Dmin [mm], it is possible to make the gate diameter Dm larger than the minimum diameter Dmim, so the speed of the molten resin that collides with the portion (opposing portion) where damage is likely to occur can be further suppressed. When the runner is a cold runner, the pipe wall (runner surface) of the runner may be configured as an inclined surface with a taper such that the diameter decreases toward the injection unit side from the gate so that the runner solidified product solidified in the runner can smoothly be removed when the resin molded product is removed from the mold.

[0024] Stainless steel, a commonly used metal material for molding dies, has a thermal conductivity of approximately 16 W / mK to 26 W / mK. This is not limited to stainless steel, but metals used for molding dies generally have relatively high thermal conductivity. Thus, when the mold has a high thermal conductivity, a portion of the molten resin flowing within the cavity or runner is likely to cool and solidify, adhering to the inner walls of the cavity (molding surface) and the inner walls of the runner (runner surface). This reduces the effective cross-sectional area of ​​the cavity or runner before the molten resin is fully filled into the cavity, making it difficult to fill the cavity with the resin without gaps. High thermal conductivity near the molding surface facilitates cooling of the molten resin on the inner walls of the cavity (molding surface), forming a surface layer (skin) on the molded product and affecting the properties of the molded product. In conventional injection molding machines equipped with metal molds, the injection pressure from the injection unit is increased to completely fill the cavity with molten resin. However, if the injection pressure of the molten resin is increased, the molten resin will collide with the molding surfaces that make up the cavity, particularly the portion of the movable mold that faces the injection gate across the cavity space, at high pressure and speed, making this portion of the mold more susceptible to localized damage and reducing the practical durability of the mold.

[0025] In one embodiment, at least a portion of the mold is constructed using a low-thermal-conductivity material containing resin, ceramic, or glass as its primary component and having a thermal conductivity of less than 10 W / mK. In another embodiment, a material containing resin, ceramic, or glass as its primary component and having a thermal conductivity of 5.0 W / mK or less, or even 4.0 W / mK or less, can be used. In another embodiment, a low-thermal-conductivity material with a thermal conductivity relatively lower than that of metal materials is used. Specifically, constructing the mold using a material with a thermal conductivity of less than 10 W / mK prevents excessive cooling of the molten resin in the cavity and runner during injection. This prevents excessive reduction in the effective flow path cross-sectional area in the runner until the cavity is completely filled, eliminating the need for high-pressure injection. This reduces the risk of damage to the portion facing the injection gate. Furthermore, molding can be performed at a lower injection pressure than with metal molds (metal dies), where the resin tends to solidify on the wall surfaces of the runner, so the injection molding device can be configured using a relatively small injection unit.

[0026] In the first mold, a portion within a distance D [mm] equal to Dm [mm] from the connecting portion is preferably made of a low thermal conductive material. This prevents the molten resin injected into the cavity from being rapidly cooled at the opposing portion. In particular, it is preferable that the opposing region of the molding surface of the first mold that faces the connecting portion is made of a low thermal conductive material. Also, in the first mold, a portion within 1 mm of the region of the molding surface of the first mold that faces the molding surface of the second mold across the cavity is preferably made of a low thermal conductive material. It is also preferable that in the second mold, a portion within 1 mm of the region of the molding surface of the second mold that faces the molding surface of the first mold across the cavity is made of a low thermal conductive material. This prevents the formation of a skin layer in the cavity. It is also preferable that in the second mold, a portion within 1 mm of the runner surface is made of a low thermal conductive material. This prevents the molten resin from solidifying in the runner. A low-thermal-conductivity material provided within 1 mm of the molding surface or runner surface is useful for realizing a molding mold with a heat-insulating layer. A protective layer made of a metal material or the like may be formed on the heat-insulating layer, and this protective layer may form the molding surface. For details on heat-insulating layers, see JP-A-9-155876, JP-A-9-239737, JP-A-2001-334534, and JP-A-2002-321246.

[0027] In one embodiment, the volume of the cavity is defined as Vc [mm 3 ], and the volume of the runner is Vr [mm 3 ], Vc [mm 3 ] <Vr[mm 3 A molding die can be constructed using a material containing resin, ceramic, or glass as a main component so as to satisfy the relationship: Conventionally, the volume of the runner has been made as small as possible in order to reduce the volume of the runner solidified material, but in the case of a molding die made of the above-mentioned materials without using metal, it is desirable to construct it in this way in order to obtain practical durability. The total volume Vn [mm 3 ] is the cavity volume Vc [mm 3 ] and runner volume Vr [mm 3In a preferred example, the total volume Vn [mm 3 ] is the total volume Vm [mm 3 ] is greater than.

[0028] A molding die according to an embodiment is lighter than a metal molding die (metal mold), making it easy to attach and detach to and from an injection molding apparatus (or injection molding system), and for example, facilitating setup changes when producing small lots. The molding die according to an embodiment uses a material containing resin, ceramic, or glass as its main component, yet has sufficient practical durability. To further enhance durability, the thickness of the non-metallic material near the molding surface or runner surface in the direction perpendicular to the molding surface or runner surface is preferably 10 mm or more.

[0029] [Embodiment] An overview of a molding die and an injection molding apparatus according to an embodiment will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view of the injection molding apparatus, showing the mold clamped state. In the mold clamped state, a cavity 2 for molding a resin molded product is defined by a fixed piece 3 (second mold) and a movable piece 4 (first mold).

[0030] The fixed piece 3 (second mold) and the movable piece 4 (first mold) are made of a material containing resin, ceramic, or glass as a main component. The fixed piece 3 and the movable piece 4 may be three-dimensional objects produced by, for example, 3D printing, or may be made by processing a base material using machining techniques such as cutting, drilling, and polishing. The fixed piece 3 and the movable piece 4 may collectively be called the molding die 5.

[0031] The fixed block 3 is attached to a fixed-side template 6 (support member), and the fixed-side template 6 is fixed to a fixed-side mounting plate 7. The fixed-side template 6 and the fixed-side mounting plate 7 are members that require sufficiently high mechanical strength and can be made of metal, but may also be made of materials other than metal. A unit formed by integrating the fixed block 3, fixed-side template 6, and fixed-side mounting plate 7 may also be called a fixed block. If the fixed block 3 has sufficient mechanical strength, the fixed block 3 may be fixed directly to the fixed-side mounting plate 7 without using the fixed-side template 6 (support member).

[0032] The movable piece 4 is attached to a movable-side mold plate 8 (support member), which is fixed to a movable-side mounting plate 9. The movable-side mold plate 8 and the movable-side mounting plate 9 are members that require sufficiently high mechanical strength and can be made of metal, but may also be made of materials other than metal. The movable piece 4, movable-side mold plate 8, and movable-side mounting plate 9 are configured to be movable as a single unit, and can move upward in the figure when the mold is closed and downward in the figure when the mold is opened. The unit formed by integrating the movable piece 4, movable-side mold plate 8, and movable-side mounting plate 9 may also be called a movable mold. If the movable piece 4 has sufficient mechanical strength, the movable piece 4 may be fixed directly to the movable-side mounting plate 9 without using the movable-side mold plate 8 (support member).

[0033] A cold runner 1, which is a flow path for molten resin, is provided on the fixed block 3, the fixed-side mold plate 6, and the fixed-side mounting plate 7. The lower end of the cold runner 1 is connected to the cavity 2 via a gate 10, and the upper end of the cold runner 1 is connected to the injection unit 11 via an opening provided in the fixed-side mounting plate 7. In other words, the cold runner 1 is a piping that connects the injection unit 11 to the cavity 2 and serves as a flow path for the molten resin injected from the injection unit 11.

[0034] Unlike a so-called hot runner, the cold runner 1 is not provided with a heater for heating the pipeline. When the cavity 2 is filled, the molten resin remaining in the cold runner 1 cools and solidifies together with the molten resin filled in the cavity. The resin molded product obtained by solidifying the molten resin injected into the cavity 2 and the runner solidified product solidified in the cold runner 1 are taken out of the mold as a connected integral solidified product. In the following description, for convenience, the integral product in which the resin molded product and the runner solidified product are connected may be referred to as a molded product with a runner.

[0035] In FIG. 1, the inner diameter of the gate 10, which is the connection part between the cold runner 1 and the cavity 2, is defined as Dm [mm]. Also, the distance between the molding surface of the movable mold 4 facing the gate 10 across the cavity 2 and the gate 10 is defined as T [mm]. In the embodiment, the mold is configured to satisfy the relationship of T [mm] < Dm [mm], so as to sufficiently increase the opening diameter of the gate and suppress the speed when the molten resin injected from the gate collides with the molding surface facing the gate across the cavity space. As a preferred example, T [mm] ≥ 0.5 [mm] can be set. As a preferred example, T [mm] < 10 [mm] can be set, T [mm] < 5 [mm] can be set, and T [mm] ≤ 3 [mm] can be set. As a preferred example, Dm [mm] ≥ 1 [mm] can be set, Dm [mm] ≤ 10 [mm] can be set, and Dm [mm] ≤ 5 [mm] can be set.

[0036] In addition, when the diameter of the resin flow path 12 (nozzle diameter) of the injection unit 11 is defined as Dn [mm], it is desirable that Dm [mm] < Dn [mm]. Therefore, it is desirable that T [mm] < Dm [mm] < Dn [mm]. As a preferred example, Dn [mm] > 5 [mm] and Dm [mm] ≤ 5 [mm] can be set.

[0037] In the example of FIG. 1, one cold runner 1 (and gate 10) is provided for one cavity 2, but a plurality of cold runners 1 (and gates 10) may be provided for one cavity 2. Even in that case, for each gate, by configuring the mold so as to satisfy the relationship of T [mm] <Dm [mm], the velocity when the molten resin injected from each gate collides with the molding surface facing the gate across the cavity space is suppressed.

[0038] The gate of the runner according to the present embodiment adopts a configuration suitable for satisfying the relationship of T [mm] <Dm [mm], and does not have to be such that the flow path diameter becomes small at the connection portion with the cavity like a so-called pin gate. Also, it does not have to be such that a gate with a small flow path diameter is connected to the side surface of the cavity like a so-called side gate.

[0039] To facilitate understanding of the configuration of the runner and the cavity in the injection molding apparatus of the embodiment, an example will be given and described for the molded product with a runner taken out from the mold after molding. As described above, the molded product with a runner refers to an object taken out as an integral body in which a resin molded product and a runner solidified product are connected.

[0040] FIG. 2(a) is an external view showing the external appearance of the molded product 23 with a runner viewed obliquely from above, and FIG. 2(b) is an external view showing the external appearance of the molded product 23 with a runner viewed obliquely from below. Further, FIG. 3 is a cross-sectional view of the molded product 23 with a runner cut along a line passing through the runner solidified product.

[0041] The molded product 23 with a runner is a resin molded product in which the resin molded product 22 and the runner solidified product 21 are integrated. The runner solidified product 21 is cut off in a subsequent process from the molded product 23 with a runner taken out from the injection molding apparatus, but depending on the use of the resin molded product 22, the molded product 23 with a runner with the runner solidified product 21 attached may be used as a product. In the figure, a state where the runner solidified product is not cut off is shown, but even when the runner solidified product 21 is cut off, a gate mark 24, which is a trace of the gate 10 at the time of molding, may remain on the resin molded product 22.

[0042] The length L of the runner solidified material corresponds to the flow path length of the cold runner 1 during molding. The thickness T (Fig. 3) of the resin molded product 22 at the gate mark 24 corresponds to the distance T (Fig. 1) between the gate 10 and the molding surface of the movable block 4 facing it. The diameter Dm (Fig. 3) of the gate mark 24 corresponds to the inner diameter Dm (Fig. 1) of the gate 10 during molding. In the example of the molded product 23 shown in the figure, L=28 [mm], D1=34 [mm], D2=35 [mm], T=1.8 [mm], and H=12 [mm].

[0043] [Examples and Comparative Examples] Examples of producing molded articles of such shapes using different molds are shown below as Examples and Comparative Examples. Table 1 shows the molding conditions common to the Examples and Comparative Examples.

[0044] [Table 1]

[0045] Next, examples and comparative examples are specifically shown. In each example and comparative example, the fixed and movable pieces are produced by cutting a block of base material made of the material specified in the "Material Name." The runner surface and molding surface of the fixed piece and the molding surface of the movable piece are made of the material specified in the "Material Name," and the thickness of these materials from the runner surface or molding surface is 10 mm or more. Furthermore, 50% or more by volume of the molding die is made of the material specified in the "Material Name." For the materials used in the molding dies exemplified below, the high-temperature tensile strength refers to the limit strength at which the material used in the molding dies will not break when subjected to tensile stress under a test temperature environment. This can be an indicator of whether the mold is susceptible to irreparable damage due to plastic deformation when used in practice. In the examples, for example, a material with a high-temperature tensile strength of 31 MPa or more at 100°C is preferably used. Also, in the examples, for example, a material with a high-temperature tensile strength of 270 MPa or less at 100°C is preferably used.

[0046] The heat distortion temperature refers to the temperature at which the amount of deflection reaches a certain value when the temperature is increased while a predetermined load is applied to the material used in the mold, and the test method is specified, for example, in JIS 7191. This can be an indicator of whether the molding surface of the mold is likely to deform during injection molding, resulting in a decrease in the shape accuracy of the resin molded product. In the examples, for example, a material with a heat distortion temperature of 150°C or higher is preferably used. In the examples, for example, a material with a heat distortion temperature of 500°C or lower is preferably used.

[0047] In the embodiment, for example, the density is 3.0 g / cm 3 The following materials are preferably used: In the embodiment, materials with thermal conductivity of 5.0 W / mK or less are preferably used.

[0048] [Example 1] Table 2 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 1, the gate diameter Dm of the gate 10 shown in FIG.

[0049] [Table 2]

[0050] When injection molding was performed using a mold made of the polyimide shown in Table 2, the pressure loss in the cold runner 1 area was 4.9 MPa, and the pressure loss in the cavity 2 area was 2.9 MPa. The total pressure loss was 7.8 MPa, which is sufficiently low compared to the high-temperature tensile strength, so no mold damage due to plastic deformation occurred. Furthermore, no mold damage due to thermal deformation of the polyimide was observed.

[0051] [Example 2] Table 3 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 2, the gate diameter Dm of the gate 10 shown in FIG.

[0052] [Table 3]

[0053] When injection molding was performed using a mold made with the chemical wood shown in Table 3, the pressure loss in the cold runner 1 area was 0.5 MPa, and the pressure loss in the cavity 2 area was 1.2 MPa. The total pressure loss was 1.7 MPa, which is a sufficiently low value compared to the high-temperature tensile strength, so no mold damage due to plastic deformation occurred. Furthermore, no mold damage due to thermal deformation of the chemical wood was observed. Chemical wood is a material that has been artificially given wood-like properties by adding an inorganic filler to the main component, urethane or epoxy resin.

[0054] [Example 3] Table 4 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 3, the gate diameter Dm of the gate 10 shown in FIG.

[0055] [Table 4]

[0056] When injection molding was performed using a mold made with the epoxy resin shown in Table 4, the pressure loss in the cold runner 1 area was 4.2 MPa, and the pressure loss in the cavity 2 area was 2.6 MPa. The total pressure loss was 6.8 MPa, which is sufficiently low compared to the high-temperature tensile strength, so no mold damage due to plastic deformation occurred. Also, no mold damage due to thermal deformation of the epoxy was observed.

[0057] [Example 4] Table 5 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 4, the gate diameter Dm of the gate 10 shown in FIG.

[0058] [Table 5]

[0059] When injection molding was performed using a mold made with the chemical wood shown in Table 5, the pressure loss in the cold runner 1 area was 13.4 MPa, and the pressure loss in the cavity 2 area was 2.7 MPa. The total pressure loss was 16.1 MPa, which was sufficiently low compared to the high-temperature tensile strength, so no mold damage due to plastic deformation occurred. Furthermore, no mold damage due to thermal deformation of the chemical wood was observed.

[0060] [Example 5] Table 6 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 5, the gate diameter Dm of the gate 10 shown in FIG.

[0061] [Table 6]

[0062] When injection molding was carried out using a mold made of the ceramics shown in Table 6, no mold damage due to plastic deformation or thermal deformation was observed.

[0063] [Example 6] Table 7 shows the material properties of the fixed piece 3 and the movable piece 4 in Example 6, the gate diameter Dm of the gate 10 shown in FIG.

[0064] [Table 7]

[0065] When injection molding was carried out using a mold made of the glass shown in Table 7, no mold damage due to plastic deformation or thermal deformation was observed.

[0066] [Comparative Example 1] The material properties of the fixed piece 3 and the movable piece 4 in Comparative Example 1, the gate diameter Dm of the gate 10 shown in Figure 1, and the ratio Dm / T of Dm to the distance T are shown in Table 8. In Comparative Example 1, metal is used as the material for the fixed piece 3 and the movable piece 4.

[0067] [Table 8]

[0068] When injection molding was performed using a metal mold made of SS400 (SUS) shown in Table 8, no mold damage due to plastic deformation or thermal deformation was observed. The pressure loss in the cold runner 1 area was 36.2 MPa, and the pressure loss in the cavity 2 area was 10.4 MPa, for a total of 46.6 MPa. SS400 has high high-temperature tensile strength and a high heat distortion temperature, so mold damage did not occur. However, due to its high thermal conductivity, the resin tends to cool and solidify on the cold runner wall. This required a high injection pressure to ensure cavity filling, and a large mold volume to withstand the high injection pressure. Because metal materials such as SS400 have a high density, the weight of the molding mold was heavier than in the examples.

[0069] Comparative Example 2 The material properties of the fixed block 3 and the movable block 4 in Comparative Example 2, the gate diameter Dm of the gate 10 shown in Figure 1, and the ratio Dm / T of Dm to the distance T are shown in Table 9. In Comparative Example 2, chemical wood is used as the material for the fixed block 3 and the movable block 4, and the molding die is configured so that the gate diameter Dm is smaller than the distance T, which corresponds to the thickness of the resin molded product directly below the gate.

[0070] [Table 9]

[0071] When injection molding was performed using a mold made of chemical wood as shown in Table 9, the pressure loss in the cold runner 1 area was 29.1 MPa, the pressure loss in the cavity 2 area was 3.9 MPa, and the total pressure loss was 33.0 MPa. The molten resin collided with the part directly below the gate 10 of the movable piece 4 in Figure 1 at a high flow rate, causing plastic deformation in this area and significantly reducing the durability of the mold.

[0072] As described above, in Examples 1 to 6, a mold was fabricated using a material containing any one of resin, ceramic, and glass as the main component, and a configuration satisfying the relationship of T [mm] < Dm [mm] was adopted. Therefore, a mold with excellent practical characteristics could be realized.

[0073] [Modification Example] A modification example will be described for the molded product with a runner molded by the injection molding apparatus of the embodiment. As described above, the molded product with a runner refers to a product in which a resin molded product and a runner solidified product are integrally taken out from a mold.

[0074] FIG. 4(a) is an external view showing the appearance of the molded product with a runner according to the modification example as viewed obliquely from above, and FIG. 4(b) is a cross-sectional view of the molded product with a runner cut along line A - B passing through the runner solidified product.

[0075] The molded product with a runner is a resin molded product in which a resin molded product 32 and a runner solidified product 31 are integrated. For the molded product with a runner taken out from the injection molding apparatus, the runner solidified product 31 is cut off as necessary, but depending on the use of the resin molded product 32, the resin molded product 32 may be used with the runner solidified product 31 attached. In the figure, a state where the runner solidified product is not cut off is shown, but even when the runner solidified product 31 is cut off, a gate mark 33, which is a trace of the gate 10 during molding, may remain on the resin molded product 32.

[0076] Also in this modification example, when the distance between the molding surface of the movable mold 4 facing the gate 10 and the gate 10 is T [mm], and the inner diameter of the gate 10 is Dm [mm], the mold is configured to satisfy the relationship of T [mm] < Dm [mm]. Further, Dm may be set in consideration of not only the thickness of the cavity directly below the gate but also the average diameter of the cross-section of the flow path of the molten resin in the cavity. In other words, Dm can be set to be larger not only than the wall thickness T1 shown in FIG. 4(b) but also than the average wall thickness of T1 to T7.

[0077] [Other Embodiments] Note that the present invention is not limited to the embodiments and examples described above, and many modifications are possible within the technical idea of the present invention. For example, it is possible to implement by combining all or part of the different embodiments and examples described above.

[0078] In the above description, an example in which the movable piece and the fixed piece are formed of the same kind of material is shown, but the movable piece and the fixed piece may be formed using a different kind of material containing any one of resin, ceramic, and glass as a main component.

[0079] In addition, if there is a description in this specification such as "A is B", even if the description "A is not B" is omitted, it can be said that this specification discloses "A is not B". This is because when the description "A is B" is given, it is premised that the case of "A is not B" is considered.

[0080] This specification discloses at least the following matters. [Item 1] A first mold having a first molding surface, A second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion, When the first mold and the second mold are clamped, a runner is defined by the runner surface, and a cavity is defined by the first molding surface and the second molding surface, The material constituting at least a part of the first mold and the second mold contains any one of resin, ceramic, and glass as a main component, Let the shortest distance between the connecting portion and the first molding surface be T [mm], When the inner diameter of the connecting portion is Dm [mm], Satisfying the relationship of T [mm] < Dm [mm], A molding die characterized by the above. [Item 2]<000035​​​​​ Dm [mm] ≦ 5 [mm]. 3. The mold according to item 1 or 2, characterized in that: [Matter 4] The volume of the cavity is Vc [mm 3 ]year, The volume of the runner is Vr [mm 3 ], Vc [mm 3 ] <Vr[mm 3 ], satisfying the relationship, 4. The mold according to any one of items 1 to 3, characterized in that: [Matter 5] The high-temperature tensile strength of the material is 31 MPa or more at 100 ° C. 5. The mold according to any one of items 1 to 4, characterized in that: [Matter 6] The high-temperature tensile strength of the material is 270 [MPa] or less at 100 [°C]. 6. The mold according to any one of items 1 to 5, characterized in that: [Matter 7] The heat distortion temperature of the material is 150°C or higher. 7. The mold according to any one of items 1 to 6, characterized in that: [Matter 8] The heat distortion temperature of the material is 500°C or less. 8. The mold according to any one of items 1 to 7, characterized in that: [Matter 9] The density of the material is 3.0 [g / cm 3 ] is less than or equal to 9. The mold according to any one of items 1 to 8, characterized in that: [Matter 10] The thermal conductivity of the material is 5.0 [W / mK] or less. 10. The mold according to any one of items 1 to 9, characterized in that: [Matter 11] When the length of the flow path of the runner is L [mm], L [mm] > 10 [mm], and 11. The mold according to any one of items 1 to 10, [Matter 12] An opposing region of the first molding surface that faces the connecting portion is made of the material. 12. The mold according to any one of items 1 to 11, characterized in that: [Matter 13] In the first mold, a portion of the first molding surface within 1 mm from a region facing the second molding surface is made of the material. 13. The mold according to any one of items 1 to 12, characterized in that: [Matter 14] In the second mold, a portion of the second molding surface within 1 mm from a region facing the first molding surface is made of the material. 14. The mold according to any one of items 1 to 13, [Matter 15] In the second mold, a portion within 1 mm from the runner surface is made of the material. 15. The mold according to any one of items 1 to 14, [Matter 16] The runner is a cold runner. 16. The mold according to any one of items 1 to 15, [Matter 17] the first mold includes a metal support member that supports the portion made of the material; 17. The mold according to any one of items 1 to 16, [Matter 18] The main component of the material is polyimide resin. 18. The mold according to any one of items 1 to 17, [Matter 19] The main component of the material is epoxy resin. 18. The mold according to any one of items 1 to 17, [Matter 20] a first mold having a first molding surface; A second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion, which is composed of a material with polyimide resin as the main component in an amount of 50% by volume or more, characterized by the molding die. [Item 21] The molding die according to any one of Items 1 to 20, and an injection unit for injecting molten resin into the runner, characterized by the injection molding apparatus. [Item 22] When the nozzle diameter of the injection unit is Dn [mm], satisfying the relationship of Dm [mm] < Dn [mm], characterized by the injection molding apparatus according to Item 21. [Item 23] Using the injection molding apparatus according to Item 21 or 22, injecting molten resin from the injection unit into the runner, filling the molten resin into the cavity, and then solidifying it, characterized by the method for manufacturing a resin molded product.

Explanation of Reference Numerals

[0081] 1 ··· Cold runner / 2 ··· Cavity / 3 ··· Fixed platen / 4 ··· Movable platen / 5 ··· Mold / 6 ··· Fixed-side mold plate / 7 ··· Fixed-side mounting plate / 8 ··· Movable-side mold plate / 9 ··· Movable-side mounting plate / 10 ··· Gate / 11 ··· Injection unit / 12 ··· Resin flow path / 21 ··· Runner solidified matter / 22 ··· Resin molded product / 23 ··· Molded product with runner / 24 ··· Gate mark / 31 ··· Runner solidified matter / 32 ··· Resin molded product / 33 ··· Gate mark

Claims

1. a first mold having a first molding surface; a second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion; When the first mold and the second mold are clamped together, a runner is defined by the runner surface, and a cavity is defined by the first molding surface and the second molding surface; a material constituting at least a portion of the first mold and the second mold contains, as a main component, any one of resin, ceramic, and glass; The shortest distance between the connecting portion and the first molding surface is T [mm], When the inner diameter of the connecting portion is Dm [mm], The relationship T [mm] < Dm [mm] is satisfied. A molding die characterized by:

2. In the first mold, a portion within a distance D [mm] equal to Dm [mm] from the connecting portion is made of the material. The mold according to claim 1 .

3. The relationship Dm [mm]≦5 [mm] is satisfied. The mold according to claim 1 .

4. The volume of the cavity is Vc [mm ３ ]year, The volume of the runner is Vr [mm ３ ], Vc [mm ３ ]<Vr[mm ３ ], satisfying the relationship The mold according to claim 1 .

5. The high-temperature tensile strength of the material is 31 MPa or more at 100 ° C. The mold according to claim 1 .

6. The high-temperature tensile strength of the material is 270 MPa or less at 100 ° C. The mold according to claim 1 .

7. The heat distortion temperature of the material is 150°C or higher. The mold according to claim 1 .

8. The heat distortion temperature of the material is 500°C or less. The mold according to claim 1 .

9. The density of the material is 3.0 [g / cm ３ ]or less, The mold according to claim 1 .

10. The thermal conductivity of the material is 5.0 [W / mK] or less. The mold according to claim 1 .

11. When the length of the flow path of the runner is L [mm], The relationship L [mm] > 10 [mm] is satisfied. The mold according to claim 1 .

12. an opposing region of the first molding surface that faces the connecting portion is made of the material; The mold according to any one of claims 1 to 10.

13. In the first mold, a portion of the first molding surface within 1 mm of a region facing the second molding surface is made of the material. The mold according to any one of claims 1 to 10.

14. In the second mold, a portion of the second molding surface within 1 mm from a region facing the first molding surface is made of the material. The mold according to any one of claims 1 to 10.

15. In the second mold, a portion within 1 mm from the runner surface is made of the material. The mold according to any one of claims 1 to 10.

16. The runner is a cold runner. The mold according to any one of claims 1 to 10.

17. the first mold includes a metal support member that supports the portion made of the material; The mold according to any one of claims 1 to 10.

18. The main component of the material is polyimide resin. The mold according to any one of claims 1 to 10.

19. The main component of the material is epoxy resin. The mold according to any one of claims 1 to 10.

20. a first mold having a first molding surface; a second mold having a second molding surface and a runner surface connected to the second molding surface by a connecting portion; 50% or more by volume of the material is composed mainly of polyimide resin. A molding die characterized by:

21. The mold according to any one of claims 1 to 10, an injection unit that injects molten resin into the runner, An injection molding apparatus characterized by:

22. When the nozzle diameter of the injection unit is Dn [mm], The relationship Dm [mm] < Dn [mm] is satisfied.

22. The injection molding apparatus of claim 21.

23. Using the injection molding apparatus according to claim 21, molten resin is injected from the injection unit into the runner, and the molten resin fills the cavity and then solidifies; A method for producing a resin molded product, comprising:

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