Injection molding machine and method for manufacturing molded article using injection molding machine

Abstract

To provide an injection molding machine capable of manufacturing a metal composite molded article in which multiple molded articles are joined in the lateral direction relative to the injection direction.SOLUTION: An injection molding machine includes multiple injection devices 3A, 3B, a single mold clamping device, and a control device for the multiple injection devices 3A, 3B. The control device controls the multiple injection devices 3A, 3B under different injection conditions such that the injection steps S3 of all the injection devices 3A, 3B at least partially overlap with each other.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an injection molding machine and a method for manufacturing a molded product using the injection molding machine. [Background technology]

[0002] An injection molding machine equipped with a plurality of injection devices is known. Patent Document 1 describes an injection molding machine that manufactures a composite molded product by two-color molding. This injection molding machine includes a fixed platen, a movable platen, a rotary table supported by the movable platen, and two injection units. Two fixed dies and two movable dies can be mounted on the fixed platen and the rotary table, respectively. When injection by one injection unit is completed, injection by the other injection unit is performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-119848 A Summary of the Invention [Problem to be solved by the invention]

[0004] The injection molding machine described in Patent Document 1 is used for two-color molding, and therefore the composite molded product has a structure in which two layers are overlapped with respect to the injection direction. On the other hand, such an injection molding machine cannot produce a composite molded product in which two molded products are joined laterally with respect to the injection direction. The present disclosure aims to provide an injection molding machine capable of producing a composite molded product in which multiple molded products are joined laterally with respect to the injection direction. [Means for solving the problem]

[0005] The injection molding machine of the present disclosure includes a plurality of injection devices and a control device for the plurality of injection devices. The control device controls the plurality of injection devices under different injection conditions such that the injection processes of all the injection devices at least partially overlap. Effect of the Invention

[0006] According to the present disclosure, it is possible to provide an injection molding machine capable of manufacturing a composite molded product in which a plurality of molded products are joined in a direction transverse to the injection direction. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a top view of an injection molding machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partial front view of the injection molding machine shown in FIG. [Diagram 3] FIG. 2 is a perspective view showing an example of a composite molded product. [Figure 4] FIG. 2 is a schematic process diagram showing a molding cycle in the injection molding machine shown in FIG. [Diagram 5] FIG. 4 is a diagram showing the state of the composite molded product shown in FIG. 3 in a mold. [Figure 6] FIG. 1 is a schematic diagram showing various molded parts and their injection conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An injection molding machine 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic top view of the injection molding machine 1, and FIG. 2 shows a partial front view of part C in FIG. 1. In the following description, the axial direction or movement direction of the screw is called the X direction, the direction in which the two injection units are arranged is called the Y direction, and the vertical direction is called the Z direction. The X direction and the Y direction are in a horizontal plane and are perpendicular to each other. Terms such as "forward" and "forward" refer to the movement, direction, position, etc. of the screw approaching the mold clamping unit in the X direction, and terms such as "reverse" and "rear" refer to the movement, direction, position, etc. of the screw moving away from the mold clamping unit in the X direction. The direction in which the metal material is injected is called the injection direction.

[0009] <Overall composition> The injection molding machine 1 is a horizontal metal injection molding machine. The injection molding machine 1 is generally composed of a clamping device 2 that clamps a mold, a plurality of (two in this embodiment) injection devices 3A, 3B that heat, melt, and inject the metal material to be injected, and a control device 4. The control device 4 controls the clamping device 2 and the plurality of injection devices 3A, 3B. Only one clamping device 2 and one control device 4 are provided, and they are shared between the plurality of injection devices 3A, 3B. The metal material that is heated, melted, and injected is sometimes called molten metal. The metal material may be injected in a semi-molten state or in a completely molten state. The metal to be injected is typically a light metal such as a magnesium alloy or an aluminum alloy, but the type of metal is not limited. Note that the present disclosure is not limited to metal injection molding machines, and can also be applied to resin injection molding machines.

[0010] <Mold clamping device 2> The mold clamping unit 2 includes a fixed platen 21 that is fixed on the bed 5 and to which a fixed mold M1 is attached, and a movable platen 22 to which a movable mold M2 is attached. As shown in Fig. 1, the fixed platen 21 is provided with two openings 21A, 21B for receiving the injection nozzles 37A, 37B at positions facing the injection nozzles 37A, 37B of the two injection units 3A, 3B. A cavity M3 is formed between the fixed mold M1 and the movable mold M2 and is filled with molten metal.

[0011] 1, on the opposite side of the fixed platen 21 with respect to the movable platen 22, a clamping housing 24 capable of sliding on the bed 5 is provided. The fixed platen 21 and the clamping housing 24 are connected by a plurality of tie bars 25. The movable platen 22 can slide on the bed 5 between the fixed platen 21 and the clamping housing 24. A toggle type clamping mechanism 26 driven by an electric ball screw is provided between the movable platen 22 and the clamping housing 24. A hydraulic clamping cylinder may be provided instead of the toggle type clamping mechanism 26.

[0012] <Injection device 3A, 3B> The two injection units 3A, 3B are mounted on a common base 6. As shown in Fig. 1, the two injection units 3A, 3B are disposed symmetrically with respect to the center line C1 of the injection molding machine 1. Therefore, the center lines CA, CB of the cylinders 32A, 32B of the two injection units 3A, 3B are parallel to each other. Since the width of each injection unit 3A, 3B is kept small, the width of the injection molding machine 1 is also kept small, and an increase in the installation area is suppressed.

[0013] Since the two injection units 3A and 3B have the same configuration, the injection unit 3A will be mainly described here. In the drawings, the components of the injection units 3A and 3B are distinguished by the suffixes A and B. Components designated by the same numbers (e.g., cylinders 32A and 32B) have the same structure unless otherwise specified. In other words, among the components of the injection unit 3B, components that are not described or are not shown (e.g., the screw of the injection unit 3B) have the same structure as the corresponding components of the injection unit 3A (e.g., the screw 33A of the injection unit 3A) unless otherwise specified.

[0014] As shown in Fig. 2, the injection device 3A has a hollow cylindrical cylinder 32A and a screw 33A housed in the cylinder 32A. The screw 33A has a screw head 35A at its front end in the X direction. The cross section of the internal space of the cylinder 32A perpendicular to the X direction is circular. The injection device 3A further has a drive mechanism 34A that is controlled by the control device 4 and drives the screw 33A. The screw 33A is driven to rotate and driven in the X direction (moves back and forth) by the drive mechanism 34A.

[0015] As shown in FIG. 2, the cylinder 32A is roughly divided into a supply section P1, a compression section P2, and a metering section P3 from the rear to the front. A hopper 36A is provided in the supply section P1, and a pellet-shaped metal material is supplied to the supply section P1. The metal material is compressed, heated, and kneaded in the compression section P2 to become molten, and is transported to the metering section P3. The metering section P3 measures the molten metal to be injected in one injection cycle (shot). A heater 39A for heating the metal material is provided on the outer periphery of the cylinder 32A. An injection nozzle 37A for supplying molten metal to the cavity M3 is attached to the tip of the cylinder 32A.

[0016] The injection molding machine 1 of this embodiment can manufacture a metal composite molded product in which different metals are joined by injecting different metal materials from each of the two injection units 3A and 3B. In recent years, multi-material design has become widespread, which aims to reduce weight and improve functionality by using multiple metal materials in appropriate places that make the most of their respective characteristics. Figure 3 shows a schematic diagram of a metal composite molded product 7 used in an instrument panel of an automobile as an example of such a metal composite molded product.

[0017] The metal composite molding 7 is made up of part A, which corresponds to the center console in the center, and part B, which corresponds to the instrument panel on the driver's side. Part A requires relatively high strength and rigidity, and is therefore made of AZ91D magnesium alloy containing 9% aluminum. Part B is made of AM60B magnesium alloy, which contains 6% aluminum and is relatively ductile, in order to absorb impacts during collisions, etc.

[0018] In the conventional method for manufacturing the metal composite molded product 7 shown in FIG. 3, the A and B parts are made separately and integrated by mechanical fastening means (rivets, screws, etc.), welding (melt welding, solid-state stir welding, etc.), adhesion, etc. However, such methods require joining or adhesion processes and tend to impose restrictions on the shape. The injection molding machine 1 of this embodiment not only simplifies the manufacturing process of the metal composite molded product 7, but also allows the optimum material to be used according to the requirements of each part, thereby contributing to the weight reduction and high functionality of the metal composite molded product 7. In addition, it is also possible to increase the degree of freedom in the shape of the metal composite molded product 7 by devising a mold.

[0019] Next, one cycle of the injection molding machine 1 will be described with reference to FIG. 4. In the following description of one cycle of the injection molding machine 1, FIG. 1 and FIG. 2 will also be referred to as appropriate. First, the control device 4 operates the clamping device 2 to close the mold (mold closing step S1). Specifically, the clamping motor (not shown) drives the electric ball screw to extend the toggle clamping mechanism 26, thereby sliding the movable platen 22 toward the fixed platen 21. When the movable mold M2 comes into contact with the fixed mold M1, the toggle clamping mechanism 26 is stopped once, and then the toggle clamping mechanism 26 is operated again to bring the movable mold M2 into close contact with the fixed mold M1 (mold clamping step S2). As a result, a cavity M3 is formed between the movable mold M2 and the fixed mold M1.

[0020] Fig. 5 is a schematic diagram showing the inside of a mold in which the metal composite molded product 7 shown in Fig. 3 is manufactured. In the following description, the molten metal forming part A in Fig. 3 may be referred to as A metal, the molten metal forming part B as B metal, the region in cavity M3 corresponding to part A as region A, and the region in cavity M3 corresponding to part B as region B. Sprues 41A, 41B, runners 42A, 42B, and gates 43A, 43B are provided in the lower part of the mold, and the molten metal is filled from the bottom to the top into regions A and B.

[0021] 4 again, following the mold clamping step S2, molten metals (metal A and metal B) are injected from the injection units 3A and 3B into the mold cavity M3 (injection step S3). The control unit 4 simultaneously operates the two injection units 3A and 3B so that the injection of molten metal from the two injection units 3A and 3B into the cavity M3 starts at approximately the same time.

[0022] Metal A is supplied from cylinder 32A shown in FIG. 2 to injection nozzle 37A, and passes through sprue 41A and runner 42A in cavity M3 shown in FIG. 5, and is filled from gate 43A into region A in cavity M3. Similarly, metal B is supplied from cylinder 32B shown in FIG. 2 to injection nozzle 37B, and passes through sprue 41B and runner 42B in cavity M3 shown in FIG. 5, and is filled from gate 43B into region B in cavity M3. In this manner, a metal composite molded product 7 in which a plurality of molded products are joined in the lateral direction (Y direction) relative to the injection direction X can be manufactured. The purity of the molten metal initially filled in cavity M3 is reduced by reacting with the mold release agent applied in advance to the surface of the mold and the air in cavity M3, and is discharged to overflow parts 44A and 44B. The injection conditions of injection units 3A and 3B will be described later.

[0023] Referring again to FIG. 4, after the injection step S3 is completed, the position of the screw 33A is maintained and pressure is continued to be applied to the cavity M3 of the mold (holding step S4). Since metal often shrinks as it solidifies, by carrying out the holding step S4, additional molten metal equivalent to the amount of shrinkage is filled, and the occurrence of sink marks can be suppressed. After the holding step S4, the molten metal in the cavity M3 is cooled and solidified (cooling step S5). During the cooling step S5, the screw 33A retreats, and the metal material is compressed, heated, and kneaded for the next cycle (melting step S6). The holding step S4 and melting step S6 are also carried out in the injection unit 3B in the same way.

[0024] Thereafter, the toggle-type clamping mechanism 26 is bent by the control device 4 to separate the movable mold M2 from the fixed mold M1 (mold opening step S7). Thereafter, an ejection device (not shown) is used to separate the metal composite molded product 7 from the movable mold M2 (ejection step S8), and the metal composite molded product 7 is removed using a robot, and unnecessary parts such as the runners 42A, 42B, gates 43A, 43B, and overflow parts 44A, 44B are cut off by pressing. The metal composite molded product 7 is completed by the above steps.

[0025] Metal A and metal B flow into cavity M3 in a molten state and come into contact with each other, so that a mixture of both metals is formed in boundary region 8 (see Figure 3) between metal A and metal B. For example, in the case of AZ91D magnesium alloy and AM60B magnesium alloy, the metal in boundary region 8 contains about 7 to 8% aluminum and has intermediate properties between the two metals. The properties and structure of the metal formed in boundary region 8 depend on the combination of metals injected from the two injection units 3A and 3B.

[0026] The shapes and sizes of the parts A and B of the metal composite molded product 7 are various. The control device 4 can control the two injection devices 3A and 3B in accordance with the configuration of the metal composite molded product 7. A representative control method will be described below with reference to FIG. 6. A is the volume of part A, V B is the volume of part B, W A is the width of part A (dimension in the Y direction), W B is the width of part B (dimension in the Y direction), H A is the height of part A (dimension in the Z direction), H B is the height of part B (dimension in the Z direction).

[0027] In Case 1 of FIG. 6, part A and part B have the same shape and dimensions. In this case, it is preferable that the injection conditions of injection device 3A and injection device B are the same. That is, injection starts from injection devices 3A and 3B at the same timing, injection is performed at the same injection rate, and injection ends at the same timing. The injection rate is the injection amount per unit time, and can be obtained by S×V when the cross-sectional area of the space in front of the screw of the cylinder is S and the injection speed in the injection direction X of the molten metal is V. It is preferable that the injection start timings of metal A and metal B coincide as much as possible. For example, if the injection of metal A starts earlier than the injection of metal B, the B region will be filled with metal A, and a molded product with the intended shape cannot be produced.

[0028] Case 2 of FIG. 6 corresponds to FIGS. 3 and 5. Here, it is assumed that part A and part B have different shapes and the same volume (V A =V B ). More specifically, it is assumed that W A <W B , H A >H B , and the depth (dimension in the X direction) is the same for part A and part B. In this case, if part A and part B are filled with metal A and metal B at the same injection rate, the height of the tip of metal A in the Z direction will gradually become higher than the height of the tip of metal B in the Z direction. As a result, the tip of metal A in the Z direction will protrude into the B region, and a molded product with the intended shape cannot be produced.

[0029] Therefore, the control unit controls the injection conditions of injection devices 3A and 3B so that the upper end in the Z direction of metal A and the upper end in the Z direction of metal B are at the same height during injection, or so that the upper end in the Z direction of metal A and the upper end in the Z direction of metal B rise at the same speed. Specifically, the injection start timings of metal A and metal B are made the same, and the injection rate of metal A < the injection rate of metal B. In this case, since the depth is constant, the injection rate of metal A: the injection rate of metal B = W A :W B . Since the injection of metal A is not completed when the injection of metal B ends, the timing at which the filling of metal A ends is later than the timing at which the filling of metal B ends.

[0030] In case 3 of Figure 6, the volumes of parts A and B are the same (V A =V B ), but the injection rate of metal B is decreased over time. Initially, the filling amount per unit time of metal B is greater than the filling amount per unit time of metal A, so part of metal B flows around to metal A. After that, the filling amount per unit time of part A becomes greater than the filling amount per unit time of metal B, so part of metal A flows around to metal B. As a result, a metal composite molded product 7 can be manufactured in which the boundary line between parts A and B is inclined. In this way, by changing the injection rate of at least one of the molten metals over time, metal composite molded products 7 of various shapes with different boundary lines can be manufactured.

[0031] In case 4 of Figure 6, the volume of part B is larger than that of part A (V A <V B ), H A =H B and the depth (dimension in the X direction) is the same for parts A and B. In this case, by making the injection rate of injection device 3A < the injection rate of injection device 3B, it is possible to make the height of the upper end of metal A in the Z direction the same as the height of the upper end of metal B in the Z direction. In this case, since the depth is constant, the injection rate of metal A: injection rate of metal B = W A :W B The injection of metal A and metal B ends at the same time.

[0032] In case 5 of Figure 6, V A <V B , H A <H B However, W A =W B and the depth (X-direction dimension) is the same for part A and part B. In this case, by making the injection rates of injection device 3A and injection device 3B the same, it is possible to align the height of the upper end of metal A in the Z direction and the height of the upper end of metal B in the Z direction. Since injection of metal B is not completed at the point in time when injection of metal A is completed, the timing at which filling of metal B is completed is later than the timing at which filling of metal A is completed.

[0033] As can be seen from these examples, the control device 4 controls the injection processes S3 of all the injection devices 3A, 3B so that they at least partially overlap. Also, the control device 4 can control the multiple injection devices 3A, 3B under different injection conditions. Specifically, the control device 4 can set at least the following injection parameters for each of the injection devices 3A, 3B individually. - Timing at which the injection of the material from the injection units 3A and 3B ends -Injection volume of material injected from injection units 3A and 3B -Injection time of the material injected from the injection units 3A and 3B -Injection rate or injection speed of the material injected from the injection units 3A and 3B

[0034] Although not described in the above example, the pressure retention time of the injection units 3A and 3B can be set individually as an injection parameter. It is also preferable to individually control and set the injection rate, injection speed, etc. according to the viscosity of the molten metal, gate resistance, etc.

[0035] In this embodiment, multiple injection units 3A, 3B are used to inject multiple metals into the mold, so the length of runners 42A, 42B, etc. can be short. Light metals used in metal injection molding have a short solidification time and solidify in a short time inside the mold, so the molten metal needs to be injected into the mold at high speed. In this embodiment, the molten metal fills cavity M3 in a short time after injection, so problems such as the molten metal solidifying midway through the process are less likely to occur.

[0036] The present invention is not limited to the above-mentioned embodiment. One of the multiple injection devices may have a different injection capacity from at least one of the other devices. For example, when manufacturing a metal composite molded product 7 in cases 4 and 5 in FIG. 6, the injection device 3A may have a smaller capacity than the injection device 3B, so that the cost of the injection molding machine 3 can be reduced. The number of injection devices is not limited to two, and may be three or more. The solid fractions of the materials at the time of injection may be different from each other.

[0037] (Additional Note) This specification includes the following disclosure. [Configuration 1] The system includes a plurality of injection units, a mold clamping unit, and a control unit for the plurality of injection units, The control device controls the multiple injection devices under different injection conditions such that injection processes of all the injection devices at least partially overlap. [Configuration 2] 2. The injection molding machine of claim 1, wherein the control device controls the multiple injection devices such that the injection volumes of material injected from the multiple injection devices are different from each other. [Configuration 3] 3. The injection molding machine according to claim 1, wherein the control device controls the multiple injection devices so that the injection times of the materials injected from the multiple injection devices are different from each other. [Configuration 4] 4. The injection molding machine according to any one of configurations 1 to 3, wherein the control device controls the multiple injection devices so that the injection rates or injection speeds of the materials injected from the multiple injection devices are different from each other. [Configuration 5] 5. The injection molding machine according to any one of configurations 1 to 4, wherein the control device controls the multiple injection devices so that the injection start timings of the materials injected from the multiple injection devices are synchronized. [Configuration 6] 6. The injection molding machine according to any one of configurations 1 to 5, wherein the control device controls the multiple injection devices so that the injection end timings of the materials injected from the multiple injection devices are different from each other. [Configuration 7] 7. The injection molding machine according to any one of configurations 1 to 6, wherein the control device controls the multiple injection devices so that the dwell times are different from one another. [Configuration 8] 8. The injection molding machine according to any one of claims 1 to 7, wherein one of the plurality of injection units has an injection capacity different from at least one of the other injection units. [Configuration 9] 9. The injection molding machine according to any one of claims 1 to 8, wherein materials injected from the multiple injection units are different from each other. [Method 1] A method for manufacturing a molded product made of a plurality of materials using an injection molding machine having a plurality of injection units, one mold clamping unit, and a control unit for the plurality of injection units, comprising the steps of: Injecting different materials from each of a plurality of injection devices into a cavity in a mold, The control device controls the multiple injection devices under different injection conditions such that the injection processes of all of the injection devices at least partially overlap. [Method 2] The method for producing a molded article according to method 1, wherein the materials injected from the multiple injection devices are different from each other. [Method 3] The method for producing a molded product according to method 1 or 2, wherein the solid fractions of the materials injected from the multiple injection devices at the time of injection are different from one another. [Explanation of symbols]

[0038] 1 injection molding machine 2 Mold clamping device 3A,3B Injection device 4. Control device M1 Fixed mold M2 movable mold M3 Cavity

Claims

1. The system includes a plurality of injection units, a mold clamping unit, and a control unit for the plurality of injection units, The control device controls the multiple injection devices under different injection conditions such that injection processes of all the injection devices at least partially overlap.

2. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection devices so that injection volumes of the material injected from the plurality of injection devices are different from each other.

3. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection devices so that the injection times of the materials injected from the plurality of injection devices are different from each other.

4. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection devices so that the injection rates or injection speeds of the materials injected from the plurality of injection devices are different from one another.

5. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection devices so that injection start timings of the materials injected from the plurality of injection devices are synchronized.

6. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection devices so that injection end timings of the materials injected from the plurality of injection devices are different from each other.

7. The injection molding machine according to claim 1 , wherein the control device controls the plurality of injection units so that the dwell times are different from one another.

8. 2. The injection molding machine according to claim 1, wherein one of said plurality of injection units has an injection capacity different from at least one of the other injection units.

9. 9. The injection molding machine according to claim 1, wherein materials injected from the plurality of injection units are different from each other.

10. A method for manufacturing a molded product made of a plurality of materials using an injection molding machine having a plurality of injection units, one mold clamping unit, and a control unit for the plurality of injection units, comprising the steps of: Injecting different materials from each of a plurality of injection devices into a cavity in a mold, The control device controls the multiple injection devices under different injection conditions such that the injection processes of all of the injection devices at least partially overlap.

11. The method for manufacturing a molded product according to claim 10 , wherein materials injected from the multiple injection devices are different from each other.

12. The method for producing a molded product according to claim 10 or 11, wherein the solid fractions of the materials injected from the plurality of injection devices at the time of injection are different from one another.

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