Core manufacturing equipment and core manufacturing method

Abstract

To provide an apparatus for making a core allowed to make a core with quality.SOLUTION: An apparatus for making a core comprises split dies 11, 12 comprising a cavity C for injecting core sand 200 into molding, a blow head 20 for injecting the core sand 200 into the cavity C and heating means for heating up the split dies 11, 12. A sub-unit 40 is provided, in the blow head 20 on a side the split dies 11, 12 are arranged, with a core sand supply passage 41 that communicates between the blow head 20 and the cavity C so as to supply the core sand 200 within the blow head 20 into the cavity C and a bend flow passage 42 that is provided as a separate system from the core sand supply passage 41 and communicates the cavity C with external. The bend flow passage 42 is connected to air transfer means 90 for sucking the air within the cavity C or supplying air into the cavity C and flow-passage switching means 80 that reverses the direction of air flowing through the bend flow passage 42.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a core manufacturing apparatus that manufactures cores by pouring core sand into a separate mold cavity, and a core manufacturing method that uses this core manufacturing apparatus. [Background technology]

[0002] When creating a hollow casting using a metal mold (casting die), a core is placed in the cavity inside the mold, and then molten metal (the raw material for the casting) is poured into the mold. Once the metal has cooled and solidified, the product (solidified metal) is removed from the mold. When the product is removed from the mold, the core is still embedded inside. By applying vibration to the core, it can be broken into small pieces, and the pieces can be removed from the product. This allows for the creation of a hollow casting product.

[0003] As described above, hollow castings are produced using cores, which are made by solidifying sand (core sand) into a predetermined shape. A widely known core-producing device (core-producing device) includes a mold (split mold) with a cavity into which core sand is poured and molded, a blow head that pours the core sand into the cavity, and a heating means for heating the split mold (see, for example, Patent Document 1). The blow head includes a tank that contains the core sand and a blowing means that blows air into the tank to pressurize it. Pressurizing the inside of the tank with the blowing means forces the core sand out of the tank and into the cavity of the split mold.

[0004] Incidentally, the above-mentioned Patent Document 1 describes that a negative pressure is created in the cavity of a mold (split mold) by a negative pressure generating means provided in the blow head (see paragraphs 0015-0017 of the same document). This makes it possible to reduce the blow pressure (blowing pressure by the above-mentioned blowing means), and prevents the core sand filled in the cavity from protruding beyond the split surface of the mold (split mold), thereby preventing burrs from forming on the cores produced (see paragraphs 0022-0023). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 07-2114239 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as shown in FIG. 5 of Patent Document 1, the core manufacturing apparatus of Patent Document 1 uses a negative pressure generating means (vacuum pump 31) to suck in the core sand 6 filled in the cavity 4. The core sand 6 sucked in by the negative pressure generating means (vacuum pump 31) is collected in a core sand separation tank 30 (see paragraph 0040 of the same document). For this reason, the core manufacturing apparatus of Patent Document 1 may produce defective cores. This is because the negative pressure generating means (vacuum pump 31) may suck in even the core sand 6 that should be filled in the cavity 4, which could result in a depletion region being formed in the cavity 4, resulting in a defective core. Another drawback is that a large amount of core sand 6 is required to produce a core.

[0007] Additionally, the core manufacturing apparatus of Patent Document 1 includes a shielding plate 24 in the negative pressure passage 18, which supplies negative pressure from the negative pressure generating means (vacuum pump 31) to the cavity 4. The supply and cutoff of negative pressure is switched depending on whether the shielding plate 24 is sunk by its own weight or pushed up by the core sand 6 (see paragraph 0038 of the same document). This makes it difficult to precisely control the supply and cutoff of negative pressure. For example, if core sand 6 adheres to the periphery of the shielding plate 24, the shielding plate 24 may not completely close even if an attempt is made to shield the negative pressure passage 18 with the shielding plate 24, making it impossible to achieve the desired control. This can adversely affect the quality of the resulting cores.

[0008] The present invention has been made to solve the above problems, and aims to provide a core manufacturing apparatus capable of manufacturing high-quality cores. It is also an object of the present invention to provide a core manufacturing method using this core manufacturing apparatus. [Means for solving the problem]

[0009] The above issues are: a split mold having a cavity for injecting and molding core sand; a blow head for injecting core sand into the cavity; a heating means for heating the split mold; A core manufacturing apparatus comprising: On the side of the blow head where the split type is arranged, a core sand supply passage that connects the blow head and the cavity and supplies the core sand in the blow head into the cavity; A vent passage is provided separately from the core sand supply passage, and connects the cavity to the outside. a subunit having The vent passage is an air transfer means for sucking air into the cavity or supplying air into the cavity; a flow path switching means for reversing the direction of air flowing through the vent flow path; connected to A core manufacturing apparatus characterized by This is solved by providing

[0010] In the core manufacturing apparatus of the present invention, when an air suction means such as a vacuum pump is used as the air transfer means, the air inside the cavity can be sucked (intaken) by this air suction means and the vent passage. This keeps the pressure inside the cavity low and prevents the core sand filled in the cavity from entering the boundary between the split molds. This makes it difficult for burrs to form on the resulting core, improving the quality of the core.

[0011] Furthermore, the core manufacturing apparatus of the present invention can reverse the direction of air flowing through the vent passage. That is, the vent passage can not only send air from inside the cavity to the outside, but also, conversely, allow outside air to flow toward the cavity. Hereinafter, the state in which air flows through the vent passage from the cavity to the outside will be referred to as the "intake state," and the state in which air flows through the vent passage from the outside to the cavity will be referred to as the "air supply state."

[0012] By being able to switch between the suction state and the air supply state in this way, it is possible to prevent a situation in which the suction state is maintained even though the suction state has been stopped. Therefore, by performing desired control, the quality of the obtained core can be improved. In addition, while there is a risk of core sand adhering to the cavity-side opening of the vent passage when the vent passage is in the suction state, by switching the vent passage to the air supply state, it is possible to remove core sand adhering to the cavity-side opening of the vent passage.

[0013] In the core manufacturing apparatus of the present invention, the flow path switching means is not particularly limited as long as it can reverse the direction of air flowing through the vent flow path, but a three-way switching valve is preferable. The three-way switching valve may be one that is switched manually or electrically. Use of a three-way switching valve makes it possible to switch between the intake state and the supply state easily and more reliably.

[0014] In the core manufacturing apparatus of the present invention, it is preferable to design the subunit so that it can be attached to and detached from the blow head. This facilitates maintenance of the subunit and blow head. Furthermore, the optimal layout of the core sand supply passage and vent passage varies depending on the shape of the core to be manufactured, and when switching the type of core to be manufactured, it is possible to accommodate this by simply replacing the subunit in addition to the split type. Furthermore, by retroactively attaching a subunit to the blow head of an existing core manufacturing apparatus (one that does not fall under the core manufacturing apparatus of the present invention), it is possible to upgrade that core manufacturing apparatus to the core manufacturing apparatus of the present invention.

[0015] In the core manufacturing apparatus of the present invention, it is preferable to provide an annular pipe surrounding the outer periphery of the blow head, and to connect the vent passages to the air transfer means and the passage switching means via the annular pipe. As already mentioned, the optimal arrangement of the vent passages varies depending on the shape of the core to be manufactured. Furthermore, the number of vent passages themselves may change. In this regard, by providing an annular pipe around the outer periphery of the blow head as described above, it becomes possible to easily accommodate changes in the number and arrangement of the vent passages.

[0016] In the core manufacturing apparatus of the present invention, it is preferable to cover the open end of the vent passage on the cavity side with a filter member that is breathable but impermeable to core sand. This makes it possible to prevent core sand from entering the vent passage. This not only prevents core sand from being wasted, but also makes it less likely for the vent passage to become clogged or for the air transfer means to malfunction. On the other hand, covering the open end of the vent passage with a filter member can cause core sand to adhere to the filter member, which can cause clogging. However, in the core manufacturing apparatus of the present invention, by supplying air to the vent passage, core sand adhering to the filter member can be removed. [Effects of the Invention]

[0017] As described above, the present invention makes it possible to provide a core manufacturing apparatus capable of manufacturing high-quality cores, and also to provide a core manufacturing method using this core manufacturing apparatus. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 10 is a front view showing the core manufacturing apparatus when the blow head is raised and the split mold is opened. [Figure 2] FIG. 10 is a front view showing the core manufacturing apparatus when the split molds are closed and the blow head is lowered. [Figure 3] FIG. 1 is an enlarged cross-sectional view of the split mold and the blow head in the core manufacturing apparatus, showing the state before the blow head is lowered relative to the split mold (raised state). [Figure 4] FIG. 10 is an enlarged cross-sectional view of the area around the split mold and blow head in the core manufacturing apparatus, showing the state after the blow head has been lowered relative to the split mold. [Figure 5] This is an enlarged cross-sectional view of the area around the split mold and blow head in the core manufacturing apparatus, showing the state in which core sand is being poured from the blow head into the cavity of the split mold. [Figure 6]FIG. 2 is an enlarged cross-sectional view of the split mold and blow head in the core manufacturing apparatus, showing the state after core sand has been poured into the cavity (filled state). [Figure 7] FIG. 2 is a perspective view showing a subunit of the core manufacturing apparatus turned upside down and partially broken away. [Figure 8] 10 is a time chart showing the relationship between the timing of pressurizing and depressurizing the blow head and the timing of suction and supply of air to the cavity. DETAILED DESCRIPTION OF THE INVENTION

[0019] A preferred embodiment of the core manufacturing apparatus of the present invention will be described in more detail with reference to the drawings.

[0020] Figures 1 and 2 show front views of the entire core manufacturing apparatus according to the present invention. Fig. 1 shows the state in which the blow head 20 is raised to open the split molds 11 and 12, and Fig. 2 shows the state in which the split molds 11 and 12 are closed and the blow head 20 is lowered. Figures 3 to 6 are enlarged cross-sectional views of the split molds 11 and 12 and the blow head 20 in the core manufacturing apparatus according to the present invention. Fig. 3 shows the state before the blow head 20 is lowered relative to the split molds 11 and 12 (raised state), Fig. 4 shows the state after the blow head 20 has been lowered relative to the split molds 11 and 12, Fig. 5 shows the state in the middle of pouring core sand 200 from the blow head 20 into the cavities C of the split molds 11 and 12, and Fig. 6 shows the state after the core sand 200 has been poured into the cavities C (filled state).

[0021] 1 to 6 show a Cartesian coordinate system consisting of an x-axis, a y-axis, and a z-axis. The directions of the axes of these coordinate systems are common across different figures. Hereinafter, the positive x-axis direction may be referred to as the "right" side, and the negative x-axis direction may be referred to as the "left" side. The positive y-axis direction may be referred to as the "rear" side, and the negative y-axis direction may be referred to as the "front" side. The positive z-axis direction may be referred to as the "upper" side, and the negative z-axis direction may be referred to as the "lower" side. However, these terms representing directions are used for convenience to represent the relative positional relationships of each component, and do not limit the absolute positional relationships of each component.

[0022] As shown in Figure 1, the core manufacturing apparatus of the present invention comprises split molds 11 and 12, a blow head 20, heating means 31, 32 and 33, a subunit 40, etc. These components will be described in more detail below.

[0023] 1.Divided type As shown in Fig. 3, the split molds 11 and 12 have a cavity C therein. As shown in Fig. 6, core sand 200 is poured (filled) into this cavity C, and the core sand 200 is heated, causing the core sand 200 to harden into a predetermined shape (the shape of the desired core). This forms the core. An injection port α1 for pouring the core sand 200 into the cavity C is provided at the top of the split molds 11 and 12.

[0024] The split dies 11 and 12 have a structure that allows them to be opened and closed. When molding the core, the split dies 11 and 12 are closed (Fig. 2), and when removing the core, the split dies 11 and 12 are opened (Fig. 1). As shown in Fig. 1, the split dies 11 and 12 are arranged above the base 50, facing each other in the left-right direction (x-axis direction). Hereinafter, the split die 11 may be referred to as the "first split die 11," and the split die 12 may be referred to as the "second split die 12."

[0025] The first split mold 11 is attached to a body 51 on one side (the negative side in the x-axis direction) of the base 50 via a first mounting member 13. Although the first split mold 11 is attached integrally with the first mounting member 13 in a state where it does not move, the first mounting member 13 is supported by the body 51 on one side in a state where it can rotate about an axis L1. Therefore, the first split mold 11 is able to rotate about the axis L1.

[0026] On the other hand, the second split mold 12 is attached to a body 52 on the other side (positive side in the x-axis direction) of the base 50 via a second mounting member 14 (a member fixed integrally to the second split mold 12) and a rotating member 15. Although the second split mold 12 is attached immovably relative to the second mounting member 14, the second mounting member 14 is supported in a state in which it can move (slide) in the left-right direction (x-axis direction) relative to the rotating member 15. In addition, the rotating member 15 is supported in a state in which it can rotate about an axis L1 relative to the body 52 on the other side. Therefore, the second split mold 12 can move (slide) in the left-right direction (x-axis direction) and rotate about the axis L1.

[0027] The second split mold 12 is moved (slid) in the left-right direction (x-axis direction) by an opening / closing cylinder 61. By driving this opening / closing cylinder 61 and moving the second split mold 12 along the guide bar 16, it is possible to switch between a state in which the split molds 11 and 12 are separated (a state in which the split molds 11 and 12 are open) as shown in Fig. 1 and a state in which the split molds 11 and 12 are abutting against each other (a state in which the split molds 11 and 12 are closed) as shown in Fig. 2.

[0028] The first split mold 11 and the second split mold 12 are rotated by a reversing cylinder 62. When this reversing cylinder 62 is driven, the rotating member 15 rotates. Because the first mounting member 13 and the rotating member 15 are connected by a guide bar 16, the rotational motion of the rotating member 15 is also transmitted to the first mounting member 13. Furthermore, because the guide bar 16 passes through the housing of the second mounting member 14, the rotational motion of the rotating member 15 is also transmitted to the second mounting member 14. This allows the first split mold 11 and the second split mold 12 to rotate integrally about a common axis L1, and the split molds 11, 12 can be turned upside down (so that the injection port α1 faces downward).

[0029] 2. Blow head The blow head 20 is used to inject core sand 200 into the cavity C (see FIG. 3). The blow head 20 is equipped with a tank 21 that stores the core sand 200, and blowing means (not shown) that blows air into the tank 21 to pressurize the inside of the tank 21. Examples of the blowing means include an air pump and an air cylinder. By pressurizing the inside of the tank 21 with this blowing means, the core sand 200 in the tank 21 is pushed out of the tank 21 and injected into the cavity C of the split molds 11, 12.

[0030] In the core manufacturing apparatus of this embodiment, as shown in Figure 3, a throttle port α2 is provided near the bottom of the tank 21, and a baffle plate 22 is placed below the throttle port α2. This prevents the core sand 200 in the tank 21 from falling downward in the tank 21 due to gravity. In other words, the core sand 200 will not be sent downward in the tank 21 unless the inside of the tank 21 is pressurized and the core sand 200 is pushed out.

[0031] In the core manufacturing apparatus of this embodiment, as shown in Fig. 1, the blow head 20 is housed in a frame 23. A spring 24 is attached to the frame 23. A lifting cylinder (not shown) is connected to this spring 24 for moving (raising and lowering) the blow head 20 in the vertical direction (z-axis direction) relative to the frame 23. This makes it possible to switch the vertical position of the blow head 20 between an upper position (Fig. 1) above and away from the split dies 11, 12, and a lower position (Fig. 2) close to the split dies 11, 12.

[0032] Furthermore, in the core manufacturing apparatus of this embodiment, the frame 23 itself can be moved in the front-to-rear direction (y-axis direction) by a moving means (not shown). This allows the front-to-rear position of the blow head 20 to be switched between a position directly above the split molds 11, 12 (injection position) and a position retracted rearward (positive side of the y-axis direction) from the injection position (retracted position).

[0033] 3.Heating means Heating means 31, 32, 33 (FIG. 1) are used to heat the split molds 11, 12. As shown in FIG. 6, by heating the split molds 11, 12 with core sand 200 filled in the cavity C, the core sand 200 solidifies and a core having a shape that matches the cavity C is formed. There are no particular limitations on the type of heating means 31, 32, 33 as long as they can heat the split molds 11, 12. In this embodiment, burners are used as the heating means 31, 32, 33.

[0034] Of the heating means 31, 32, and 33, the heating means 31 and 32 are provided in the split molds 11 and 12, respectively, and heat the core sand 200 (FIG. 6) in the cavity C from the side. On the other hand, the heating means 33 is provided movably above the split molds 11 and 12. When the blow head 20 is pouring the core sand 200 (FIG. 6) into the cavity C of the split molds 11 and 12, the heating means 33 is retracted to a position where it does not interfere with the blow head 20. However, once the blow head 20 has finished pouring the core sand 200 and moved to its retracted position, the heating means 33 moves directly above the split molds 11 and 12, and heats the core sand 200 near the pouring port α1 (FIG. 6) of the split molds 11 and 12 from above. This makes it possible to heat the core sand 200 in the cavity C evenly.

[0035] 4. Subunits As shown in Fig. 3, the subunit 40 is provided below the blow head 20. This subunit 40 is provided with a core sand supply passage 41 and a vent passage 42. The core sand supply passage 41 connects the inside of the tank 21 of the blow head 20 with the cavities C of the split molds 11, 12. The core sand 200 in the tank 21 is supplied to the cavities C through this core sand supply passage 41.

[0036] The vent flow path 42 connects the cavity C of the split molds 11, 12 to the outside, and is used when sending (inhaling) air from the cavity C, and conversely when sending (supplying) air into the cavity C. The vent flow path 42 is connected to an air suction means 90 and an air supply means 100 via an annular piping 70 and a flow path switching means 80, which will be described later. Both the air suction means 90 and the air supply means 100 are provided as the "air transfer means" described above.

[0037] When air is drawn into the cavity C using the vent flow path 42, the flow path switching means 80 connects the vent flow path 42 to the air suction means 90. When air is supplied into the cavity C using the vent flow path 42, the flow path switching means 80 connects the vent flow path 42 to the air supply means 100.

[0038] When the core sand 200 is poured from the blow head 20 into the cavity C of the split dies 11, 12, the vent passage 42 is used to suction air into the cavity C, thereby preventing the pressure inside the cavity C from becoming too high. This prevents the core sand 200 filled in the cavity C from entering the boundary α3 between the split dies 11, 12. This makes it difficult for burrs to form on the resulting core, improving the quality of the core.

[0039] However, if the core sand 200 in the cavity C enters the vent flow path 42, there is a risk of clogging the piping or causing a malfunction in the flow path switching means 80 or the air suction means 90. In this regard, in the core manufacturing apparatus of this embodiment, the open end of the vent flow path 42 on the cavity C side is covered with a filter member 43 that is breathable but does not allow the core sand 200 to pass through, thereby preventing the core sand 200 from entering the vent flow path 42.

[0040] In contrast, after the injection of the core sand 200 has been completed (usually after the core has been molded and the blow head 20 has retracted), the flow path switching means 80 is switched to connect the vent flow path 42 to the air supply means 100. This reverses the air flow in the vent flow path 42, and air is sent into the cavity C through the vent flow path 42. This makes it possible to discharge the core sand 200 that has entered the vent flow path 42 and to remove the core sand 200 that has adhered near the open end of the vent flow path 42 on the cavity C side (around the filter member 43), thereby preventing clogging of the filter member 43.

[0041] The vent passages 42 are provided in a system separate from the core sand supply passage 41. There are no particular limitations on the number or arrangement of the core sand supply passages 41 and vent passages 42, but in this embodiment, as shown in Fig. 7, two core sand supply passages 41 are provided at separate locations in the subunit 40, and two vent passages 42 are provided near each core sand supply passage 41. Fig. 7 is a perspective view showing a subunit 40 in a core manufacturing apparatus turned upside down and partially broken away.

[0042] In this way, by providing core sand supply passages 41 at multiple locations, it is possible to evenly and efficiently pour core sand 200 into the cavities C (FIG. 3) of the split molds 11, 12. In addition, by locating the open ends of the vent passages 42 on the cavity C side near each core sand supply passage 41, it becomes possible to efficiently perform the above-mentioned air intake and air supply operations.

[0043] The shape of the subunit 40 is not particularly limited, but in the core manufacturing apparatus of this embodiment, it is plate-shaped, as shown in Fig. 4. Each vent flow path 42 is connected to an end face of the subunit 40. A heat-resistant rubber layer 44 is provided on the underside of the subunit 40 (the surface facing the negative side in the z-axis direction in Fig. 7). As shown in Fig. 4, the underside of the subunit 40 abuts against the upper surfaces of the split dies 11, 12, and by providing this heat-resistant rubber layer 44, it is possible to soften the contact of the subunit 40 with the split dies 11, 12. Furthermore, by closely adhering the subunit 40 to the split dies 11, 12, it is possible to prevent air and core sand 200 from leaking from the boundary between the subunit 40 and the split dies 11, 12.

[0044] The subunit 40 may be provided integrally with the blow head 20 in a manner that makes it impossible to remove it, but in the core manufacturing apparatus of this embodiment, it is attached in a manner that makes it detachable from the blow head 20. Specifically, the subunit 40 is attached to the blow head 20 by gripping the edge of the plate-shaped subunit 40 in the plate thickness direction (vertical direction) with a clamp (not shown) provided on the bottom of the blow head 20. This makes it easier to perform maintenance on the subunit 40 and the blow head 20. It is also possible to switch the subunit 40 to be used depending on the shape of the core to be manufactured (the shape of the cavity C of the split molds 11, 12).

[0045] 5. Circular piping The annular piping 70 is arranged to surround the outer periphery of the blow head 20. In the core manufacturing apparatus of this embodiment, as shown in FIG. 1, it is attached to the outer periphery of the frame 23. This annular piping 70 functions to connect the vent flow paths 42 of the blow head 20 to the flow path switching means 80. This makes it possible to connect the vent flow paths 42 to appropriate locations in the annular piping 70, even if the subunit 40 is replaced with another one that has a different number or arrangement of vent flow paths 42.

[0046] 6. Flow path switching means Flow path switching means 80 switches the direction of air flowing through vent flow path 42. In the core manufacturing apparatus of this embodiment, a three-way switching valve is used as flow path switching means 80. The three-way switching valve has a total of three flow paths: one flow path (referred to as the "first flow path") and two flow paths (referred to as the "second flow path" and the "third flow path") that branch from the first flow path. By controlling the valve element built into the three-way switching valve, it is possible to switch between a state in which the second flow path is connected to the first flow path (a state in which the third flow path is not connected to the first flow path), a state in which the third flow path is connected to the first flow path (a state in which the second flow path is not connected to the first flow path), and a state in which all of the first, second, and third flow paths are blocked.

[0047] In the core manufacturing apparatus of this embodiment, the first flow path of the three-way switching valve (flow path switching means 80) is connected to the vent flow path 42 of the subunit 40 via the annular piping 70, the second flow path is connected to the air suction means 90, and the third flow path is connected to the air supply means 100. A pressure pump or the like may be used as the air supply means 100, but in the core manufacturing apparatus of this embodiment, the operating compressed air of the core manufacturing apparatus is taken into the third flow path of the three-way switching valve (flow path switching means 80).

[0048] Up to this point, we have described an embodiment in which the air suction means 90 is connected to the second flow path of the three-way switching valve (flow path switching means 80) and the air supply means 100 is connected to the third flow path. However, the objects connected to the second and third flow paths of the three-way switching valve (flow path switching means 80) are not limited to this. For example, the second flow path can be open to the outside air without being connected to the air suction means 90. In this case, the air supply means 100 is connected to the third flow path of the three-way switching valve (flow path switching means 80). In this case, the second flow path is used to release excess air to the outside air when pouring the core sand 200 into the cavity C, and the third flow path is used to remove sand that has entered the vent flow path 42 or core sand 200 that has adhered to the periphery of the open end (vent hole) of the vent flow path 42 on the cavity C side.

[0049] Although flow path switching means 80 may be manually switched, the core manufacturing apparatus of this embodiment uses an electromagnetic valve for electrical switching, which allows flow path switching means 80 to automatically switch at the specified timing, reducing the effort required to operate the core manufacturing apparatus.

[0050] 7.Air transport means Of the air transfer means, the air suction means 90 is used to suck air from the cavity C through the vent passage 42. An example of the air suction means 90 is a vacuum pump. It is preferable to use an air suction means 90 that can reduce the pressure in the cavity C to atmospheric pressure or below. The pressure in the cavity C is preferably reduced to -30 kPa (gauge pressure; the same applies below) or below, more preferably to -50 kPa or below, and even more preferably to -70 kPa or below. The lower limit of the pressure in the cavity C is not particularly limited, but is usually set to approximately -90 to -100 kPa. In the core manufacturing apparatus of this embodiment, the air suction means 90 reduces the pressure in the cavity C to approximately -85 kPa.

[0051] 7.Air supply means Of the air transfer means, the air supply means 100 is used to supply air into the cavity C through the vent passage 42. A pressure pump or the like may be used as the air supply means 100, but in the core manufacturing apparatus of this embodiment, compressed air for operating the core manufacturing apparatus is used.

[0052] 8. Operation of the core manufacturing equipment Next, the operation of the core manufacturing device of this embodiment will be described.

[0053] Before start-up, the core manufacturing apparatus has the split molds 11, 12 open and the blow head 20 positioned above and away from the split molds 11, 12, as shown in Figure 1. From this state, the open / close cylinder 61 is operated to move the split mold 12 to the left (negative side in the x-axis direction) until it abuts against the split mold 11. Once the split mold 12 abuts against the split mold 11 and mold clamping is complete, the apparatus reaches the state shown in Figure 3. By this time, core sand 200 has been charged into the tank 21 of the blow head 20.

[0054] Next, the blow head 20 is lowered (moved to the negative side in the z-axis direction) and brought into contact with the split dies 11, 12. This places the core manufacturing apparatus in the state shown in FIG. 4 (with the blow head 20 reaching the pouring position). At this point, the outlet (lower open end) of the core sand supply passage 41 of the subunit 40 is positioned directly above the pouring inlet α1 of the split dies 11, 12. Heating is also started by the heating means 31, 32 (FIG. 2) attached to the split dies 11, 12. This completes preparations for pouring the core sand 200.

[0055] Next, a blowing means (not shown) applies pressure to the upper part of the tank 21, thereby pushing the core sand 200 in the tank 21 downward in the tank 21. The core sand 200 pushed downward in the tank 21 is injected into the cavities C of the split molds 11, 12 through the core sand supply path 41 and the injection port α1, as shown in Fig. 5. At this time, the flow path switching means 80 connects the vent flow path 42 to the air suction means 90, and the air suction means 90 is driven. As a result, the air in the cavities C is sucked through the vent flow path 42 and discharged to the outside of the core manufacturing apparatus.

[0056] In this way, by reducing the pressure inside the cavity C when the core sand 200 is poured into the cavity C, the core sand 200 in the tank 21 of the blow head 20 is pulled toward the cavity C, making it easier to pour into the cavity C. Nevertheless, because the cavity C is in a reduced pressure state (a state lower than atmospheric pressure), the core sand 200 poured into the cavity C is less likely to penetrate into the boundary α3 between the split molds 11, 12. As a result, no burrs are formed on the core molded in the cavity C, making it possible to improve the quality of the core.

[0057] When the injection of the core sand 200 into the cavity C is completed (the cavity C is filled with the core sand 200), the state shown in Figure 6 is reached. Next, the pressurization of the tank 21 by the blowing means is stopped and the tank 21 is vented, lowering the pressure to atmospheric pressure.

[0058] Next, the blow head 20 is raised and retracted to the retracted position (FIG. 1). At this time, the flow path switching means 80 is switched to connect the vent flow path 42 to the air supply means 100. As a result, the core sand 200 that has entered the vent flow path 42 and the core sand 200 that has adhered near the filter member 43 is dropped.

[0059] Next, the core sand 200 in the cavity C is heated for a predetermined time by the heating means 31, 32, and hardened into a shape that follows the cavity C. After the predetermined time of heating by the heating means 31, 32, the reversing cylinder 62 (Fig. 1) is driven to rotate the split molds 11, 12 by 180° around the axis L1. This turns the split molds 11, 12 upside down, and the injection ports α1 (Fig. 6) of the split molds 11, 12 face downward. Excess core sand 200 near the injection port α1 falls into the recovery hopper 53 by gravity.

[0060] Next, the reversing cylinder 62 (FIG. 1) is driven again to turn the split molds 11, 12 upside down again. As a result, the injection port α1 of the split molds 11, 12 faces upward again. After this, the heating means 33 (FIG. 1) is moved to a position directly above the split molds 11, 12, and the heating means 33 heats the core sand 200 near the injection port α1. At this time, heating by the heating means 31, 32 is also continuing.

[0061] Once heating by the heating means 33 has finished for a predetermined time, the heating means 33 is retracted to its original position. Next, the opening / closing cylinder 61 is driven to move the split mold 12 to the right (x-axis direction) relative to the split mold 11, and the split molds 11, 12 are opened. Once the split molds 11, 12 are opened, the product (core with hardened core sand 200) inside the cavity C is removed. This allows a high-quality core to be obtained. If the next core is to be manufactured, the tank 21 of the blow head 20 is replenished with core sand 200, and the above-mentioned process is repeated.

[0062] For reference, a time chart showing the relationship between the timing of pressurizing and depressurizing the blow head 20 and the timing of suction and supply of air to the cavity C is shown in Figure 8. However, the time chart shown in Figure 8 is merely an example. The timing of pressurizing and depressurizing the blow head 20 and the timing of suction and supply of air to the cavity C can be changed as appropriate. [Explanation of symbols]

[0063] 11 First split type (split type) 12 Second split type (split type) 13 First mounting member 14 Second mounting member 15 Rotating member 16 Guide bar 20 Blow Head 21 Tank 22 Baffle Plate 23 frames 24 Spring 31 Heating means 32 Heating means 33 Heating means 40 subunits 41 Core sand supply route 42 Vent channel 43 Filter material 44 Heat-resistant rubber layer 50 base 51 One side of the structure 52 Other side structure 53 Collection Hopper 61 Opening and closing cylinder 62 Inverted Cylinder 70 Circular piping 80 Flow path switching means 90 Air suction means (air transfer means) 100 Air supply means (air transfer means) 200 core sand C cavity α1 inlet α2 aperture Alpha 3 split type boundary

Claims

1. A split mold having a cavity for injecting and molding core sand; a blow head for injecting core sand into the cavity; A heating means for heating the split mold; A core manufacturing apparatus comprising: On the side of the blow head where the split type is arranged, a core sand supply passage that communicates the blow head and the cavity and supplies the core sand in the blow head to the cavity; A vent passage is provided separately from the core sand supply passage, and connects the cavity to the outside. A subunit having The vent passage is an air transfer means for sucking air into the cavity or for supplying air into the cavity; A flow path switching means for reversing the direction of air flowing through the vent flow path; Connected to A core manufacturing apparatus comprising:

2. 2. A core manufacturing apparatus as set forth in claim 1, wherein the flow path switching means is a three-way switching valve.

3. 2. The core manufacturing apparatus according to claim 1, wherein the subunit is structured so as to be detachable from the blow head.

4. An annular pipe is provided around the outer periphery of the blow head, The vent passage is connected to the air transfer means and the passage switching means via the annular piping. The core manufacturing apparatus according to any one of claims 1 to 3.

5. 5. A core manufacturing apparatus as recited in claim 1, wherein an open end of the vent passage on the cavity side is covered with a filter member which is breathable but does not allow core sand to pass through.

6. A method for producing a core using the core production apparatus according to any one of claims 1 to 5.

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