Mold equipment

Abstract

To avoid or suppress adhesion to the mold. [Solution] A mold apparatus for obtaining a molded product of a predetermined shape by injecting and filling a molding material, which is a mixture of powder and a binder, into a cavity formed by a fixed mold and a movable mold, comprising: a movable part 7a that faces the inner surface of the cavity or the inner surface of a part communicating with the cavity and is retractable from the cavity; and an elastic member 7c that presses the movable part 7a toward the cavity side or toward the part 5 side, wherein the elastic force of the elastic member 7c is set to be smaller than the pressing force of the molding material on the cavity when the molding material is injected and to be large enough to push the movable part back toward the cavity side after filling into the cavity is complete.

Description

Technical Field

[0001] The present invention relates to an apparatus for performing molding by filling a fluid material into a mold of a predetermined shape and solidifying it, and particularly to a mold apparatus for obtaining a molded product from a molding material obtained by mixing a granular material and a binder.

Background Art

[0002] Patent Document 1 describes a mold apparatus for molding cores. The mold apparatus is configured to avoid the situation where the molded core adheres to the mold. Specifically, a groove serving as an injection hole for injecting core sand into the cavity is formed in the fixed mold, the width of the open end of the groove is made wider than the width at the bottom side, and the open end of the groove is configured to be closed by a parting surface which is a flat portion in the movable mold.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the mold apparatus described in Patent Document 1, most of the core that is molded at the injection hole is fitted into the groove on the fixed mold side, resulting in a large contact area with the fixed mold, while the contact area with the movable mold is smaller as it is in contact with the movable mold on a flat surface. The mold apparatus described in Patent Document 1 avoids or suppresses the core sticking to the movable mold by differentiating the way the core contacts the fixed mold and the way it contacts the movable mold. However, even if the configuration described in Patent Document 1 can avoid or suppress the core sticking to the movable mold, it does not have a means to avoid or suppress the core sticking to the fixed mold. Furthermore, the mold apparatus described in Patent Document 1 has not sufficiently considered the factors that cause the core to stick to the mold. As a result, the molded core may stick to the fixed mold, and when removing the molded product after opening one side, the molded product may break, or the surface may peel or be damaged.

[0005] This invention has been made in view of the above-mentioned technical problems, and aims to provide a mold apparatus that can avoid or suppress adhesion to the mold. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a mold apparatus for obtaining a molded product of a predetermined shape by injecting and filling a molding material, which is a mixture of powder and a binder, into a cavity formed by a fixed mold and a movable mold, wherein the apparatus has a movable part that faces the inner surface of the cavity or the inner surface of a part communicating with the cavity and is retractable from the cavity, and an elastic member that presses the movable part toward the cavity side or the part side, wherein the elastic force of the elastic member is set to be smaller than the pressing force of the molding material against the cavity when the molding material is injected and to be large enough to push the movable part back toward the cavity side after the filling of the cavity is complete.

[0007] In the present invention, the location where the movable part is provided may include a location where the flow channel area of ​​the molding material is smaller than the flow channel area on the upstream side.

[0008] In the present invention, the location where the movable part is provided may include a location where the flow path of the molding material is curved.

[0009] In the present invention, the movable part may be further provided with a pressurizing unit that selectively applies fluid pressure toward the cavity side or the location. [Effects of the Invention]

[0010] In this invention, when filling the cavity with molding material, the pressure of the molding material increases due to the narrowing or bending of the flow path. The movable part, which is pressed toward the cavity side or a point communicating with the cavity by an elastic member, is configured to be pushed back against the elastic member by a pressure of the molding material exceeding a predetermined level. As a result, the movable part retracts due to the increased pressure of the molding material during filling. Consequently, the increase in pressure of the molding material is mitigated by the increase in volume of the cavity or the point communicating with it, thereby preventing or suppressing the seepage of binder contained in the molding material or the molded product from sticking to the mold and being damaged by the binder. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic longitudinal cross-sectional view showing an example of a mold apparatus according to the present invention. [Figure 2] This is a diagram showing an example of the cavity shape, and is a front view of a fixed type. [Figure 3] This is a partial plan view showing the plug, guide, and spring as a pressure regulating mechanism. [Modes for carrying out the invention]

[0012] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the embodiments described below are merely examples of how the present invention can be implemented and do not limit the invention.

[0013] The mold apparatus 1 according to the present invention is a device for forming a core of a predetermined shape by pouring a molding material, which is a mixture of powder or granular material such as sand and a binder, into a cavity. An example of this apparatus is schematically shown in Figures 1 and 2. A fixed mold 3 and a movable mold 4 are provided to form the cavity 2. The fixed mold 3 is fixed to a machine frame or machine base (not shown). In contrast, the movable mold 4 is positioned to move back and forth relative to the fixed mold 3. When the movable mold 4 comes into close contact with the front of the fixed mold 3, i.e., the mold is closed, the cavity 2 is formed between the movable mold 4 and the fixed mold 3. Conversely, when the movable mold 4 moves away from the fixed mold 3, i.e., the mold is opened, the cavity 2 is opened and the core is removed. The surfaces of the movable mold 4 and the fixed mold 3 that face each other and come into close contact are called the trim surfaces. Note that in Figures 1 and 2, components not directly related to the present invention, such as holes for air venting, have been omitted.

[0014] In the examples shown in Figures 1 and 2, the cavity 2 is rectangular in shape, and recesses 3a and 4a corresponding to the desired core shape, i.e., the shape of the cavity 2, are formed in the fixed mold 3 and the movable mold 4, respectively. An inlet channel 5 is provided for introducing the molding material into the cavity 2. In the examples shown in Figures 1 and 2, the inlet channel 5 is a channel that communicates with one end of the cavity 2, and since the molding material filled here does not become part of the core, it is a through-hole with a cross-sectional area smaller than the cross-sectional area of ​​the cavity 2 (i.e., the channel area). The inlet channel 5 may also be formed by recesses provided on the opposing surfaces of the fixed mold 3 and the movable mold 4, similar to the cavity 2, or it may be formed by a recess provided only in the fixed mold 3.

[0015] In Figures 1 and 2, the symbol "6" indicates a plate, and plate 6 is installed in close contact with the upper surfaces of the fixed type 3 and the movable type 4. A through-hole is formed in plate 6 that communicates with the inlet channel 5, and the inlet channel 5 is the portion including this through-hole.

[0016] A pressure regulating mechanism 7 is provided in the inlet passage 5. The pressure regulating mechanism 7 is a mechanism for releasing pressure when the pressure of the molding material during filling is high, and mainly consists of a plug 7b which corresponds to a movable part fitted into the guide 7a, and an elastic member (specifically a spring) 7c which presses the plug 7b toward the inlet passage 5. Figure 3 is a top view of the pressure regulating mechanism 7, in which a housing section 8 is formed at a predetermined location on the upper side of the fixed mold 3, and the pressure regulating mechanism 7 is housed inside the housing section 8. The housing section 8 is a recess that opens to the inlet passage 5.

[0017] A guide 7a is fitted into the end of the housing section 8 on the side of the inlet passage 5. The guide 7a is a cylindrical member, and a plug 7b is slidably fitted inside it. The plug 7b is a short, axial member with a flange 7d at its rear end, and the position where the flange 7d catches on the rear end of the guide 7a is the forward end. At this forward end, the tip of the plug 7b is flush with the tip surface of the guide 7a, and the tip surfaces of the plug 7b and the guide 7a are flush with the inner surface of the inlet passage 5. The cross-sectional shape of the hollow portion formed in the guide 7a and the cross-sectional shape of the plug 7b fitted therein may be any appropriate shape, such as a rectangle or a circle. A spring 7c is placed on the rear end side (flange 7d side) of the plug 7b, and the plug 7b is pushed toward the front side (inlet passage 5 side) by the spring 7c. The pressure regulating mechanism 7 is a mechanism for reducing the pressure of the molding material by retracting the plug 7b when the pressure of the molding material is excessively high. Therefore, the elastic force of the spring 7c is set to retract the plug 7b when the pressing force from the molding material exceeds a predetermined pressure. Furthermore, since the molding material maintains a predetermined pressure after filling the cavity 2, the elastic force of the spring 7c is set so that the plug 7b does not retract at that pressure.

[0018] A pressure passage 9 that opens to a housing portion 8 housing a pressure regulating mechanism 7 is provided. The pressure passage 9 corresponds to a pressurizing portion in the embodiment of the present invention, and is a flow passage for supplying and discharging a pressurized fluid such as compressed air to and from the housing portion 8, and is formed by penetrating a predetermined portion of the fixed mold 3. Incidentally, a sealing material (not shown) is provided between the outer peripheral surface of the plug 7b and the inner peripheral surface of the guide 7a.

[0019] Since the plug 7b can be pressed toward the tip side by the above-described spring 7c and the fluid pressure of the pressurized fluid, when the plug 7b cannot be reliably pressed toward the tip side only by the spring 7c, by supplying the pressurized fluid to the housing portion 8, the plug 7b can be reliably moved to the inlet passage 5 side. That is, the tip surface of the plug 7b can be made flush with the inner surface of the inlet passage 5, and it is possible to avoid the molding material from entering the plug 7b side or unnecessary convex portions from occurring in the molded product due to this.

[0020] According to the mold apparatus according to the present invention described above, sticking of the molded product can be avoided or suppressed as follows. The movable mold 4 is brought into close contact with the fixed mold 3 to perform mold closing, and in that state, the molding material is injected from the inlet passage 5 toward the cavity 2. The molding material is a fluid material obtained by mixing a granular material and a binder, and is pushed into the inlet passage 5 by an appropriate injector (not shown). In that case, the molding material staying in the inlet passage 5 does not become a part of the molded product (for example, a core) and is a portion to be discarded, so the inlet passage 5 is a narrow flow passage. Therefore, in order to ensure the filling amount per unit time, the pressure of the molding material filled under pressure becomes high in the portion of the inlet passage 5 and the like. When the pressure of the molding material in the inlet passage 5 becomes higher than a predetermined pressure, the force pushing the plug 7b becomes larger than the elastic force of the spring 7c, and the plug 7b retreats. As a result, since the volume of the inlet passage 5 increases, the pressure of the molding material inside it decreases or the increase in pressure is suppressed.

[0021] The molding material flows into the cavity 2 through the inlet channel 5 and fills the cavity. Since the flow area of ​​the cavity 2 is larger than that of the inlet channel 5, the pressure of the molding material does not rise significantly. The air inside the cavity 2 is discharged through an air vent (not shown). The filling of the molding material is completed when the cavity 2 is filled with the molding material. At the time the injection of the molding material is completed, a low pressure is applied to account for the shrinkage of the molding material, but this pressure is lower than the pressure generated during the injection of the molding material. Therefore, the plug 7b moves forward towards the inlet channel 5 side by the elastic force of the spring 7c, pushing the molding material that has entered its tip towards either the inlet channel 5 side or the cavity 2 side. In this case, if the plug 7b does not move smoothly for any reason, pressurized fluid is supplied into the housing 8 from the pressurized passage 9 to forcibly move the plug 7b forward.

[0022] Then, the mold is opened and the molded product (core) is removed. At this point, the binder on the surface layer has hardened, so the binder does not seep out any further, nor does it cause the molded product (core) to stick to the inner surface of the cavity 2. In other words, with the mold apparatus 1 according to the present invention, it is possible to prevent the molded product from sticking to the fixed mold 3 or the movable mold 4, and thus preventing damage to the molded product.

[0023] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented. For example, the pressure regulating mechanism described above may be provided at a location where the pressure increases due to the structure of the location where the molding material flows (i.e., the flow path) when filling the molding material. Therefore, in addition to the above-described inlet flow path, a pressure regulating mechanism mainly composed of the above-described plug may be provided at a location where the pressure may increase, such as a location where the flow path area in the cavity is narrow, or a location that is curved or bent. That is, a plurality of pressure regulating mechanisms may be provided. In the above-described embodiment, the plug is inserted into the guide so that it can move back and forth. However, a plug that is pushed backward by the molding material when the pressure of the molding material is high, or a member corresponding thereto, may be configured to move back and forth without depending on the guide, and the shape of the plug or a member corresponding thereto can be appropriately set as needed. Furthermore, in the present invention, the shape of the molded product or the cavity is of course not limited to the shapes exemplified in the above-described embodiment.

Explanation of Signs

[0024] 1 Mold device 2 Cavity 3 Fixed mold 3a, 4a Recesses 4 Movable mold 5 Inlet flow path 6 Plate 7 Pressure regulating mechanism 7a Guide 7b Plug 7c Spring 7d Flange 8 Accommodation part 9 Pressurization path

Claims

1. A mold apparatus for obtaining a molded product of a predetermined shape by injecting and filling a molding material, which is a mixture of powder and granules and a binder, into a cavity formed by a fixed mold and a movable mold, A movable part facing the inner surface of the cavity or the inner surface of a part communicating with the cavity, and which is retractable from the cavity, The movable part has an elastic member that presses it against the cavity side or the location side, The elastic force of the elastic member is set to be smaller than the pressing force of the molding material against the cavity during injection, and to be large enough to push the movable part back towards the cavity after filling of the cavity is complete. A mold apparatus characterized by the following features.

2. A mold apparatus according to claim 1, The location where the movable part is provided includes a location where the flow channel area through which the molding material flows is smaller than the flow channel area on the upstream side. A mold apparatus characterized by the following features.

3. A mold apparatus according to claim 1, The location where the movable part is provided includes a location where the flow path of the molding material is curved. A mold apparatus characterized by the following features.

4. A mold apparatus according to any one of claims 1 to 3, The movable part is further provided with a pressurizing unit that selectively applies fluid pressure toward the cavity side or the location. A mold apparatus characterized by the following features.

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