Powder / granular material filling device, molded article manufacturing device, powder / granular material filling method, molded article manufacturing method

Abstract

In the present invention, an outflow port (25a) of a storage tank (23) storing a powder / granular material is abutted against a filling port (11b) of a forming mold (11, 12), and compressed air is supplied into the storage tank so that the powder / granular material inside the storage tank is caused to be blown out of the outflow port together with the compressed air and fill the forming mold. When the outflow port is drawn away from the filling port after the filling with the powder / granular material, air inside the storage tank is sucked out so that the powder / granular material falling from the outflow port is also suctioned into the storage tank along with the air. By merely adding the function of suctioning the air inside the storage tank in this manner, it is possible to prevent powder / granular material from falling from the outflow port of the storage tank and being wasted.

Description

Powder and Granular Material Filling Device, Formed Object Manufacturing Device, Powder and Granular Material Filling Method, Formed Object Manufacturing Method

[0001] The present invention relates to a technique for manufacturing a formed object made of powder and granular materials by filling a space inside a mold with granular or powdered powder and granular materials and then solidifying the powder and granular materials inside the mold.

[0002] After filling a space inside a mold with granular or powdered powder and granular materials such as casting sand, it is widely practiced to manufacture formed objects such as cores by solidifying the powder and granular materials filled in the mold. Incidentally, as a method for solidifying the powder and granular materials in the mold, various methods such as heating, pressurization, and reaction treatment with a predetermined gas are used. Thus, when manufacturing a molded object by solidifying the powder and granular materials filled inside the mold, if there is a portion inside the mold where the powder and granular materials are not filled, the resulting formed object will be a defective product.

[0003] Therefore, in order to fill the inside of the mold with powder and granular materials without any gaps, the following method is adopted. First, a filling port is formed on the upper surface of the mold so that the powder and granular materials supplied from the filling port flow into the inside of the mold by their own weight. Further, a plurality of vent holes that allow air to pass through but do not allow the powder and granular materials to pass through are formed at multiple locations inside the mold. Then, after bringing the outlet of the powder and granular materials provided at the bottom surface of the storage tank storing the powder and granular materials into contact with the filling port of the mold, pressurized air is supplied into the storage tank, and the powder and granular materials in the storage tank are blown out from the outlet together with the pressurized air to fill the inside of the mold with the powder and granular materials. By doing so, by forming a plurality of vent holes at appropriate locations inside the mold, the inside of the mold can be filled with powder and granular materials without any gaps (Patent Document 1). Also, after filling the powder and granular materials, the pressurized air in the storage tank is released to the outside air to return the pressure in the storage tank to atmospheric pressure.

[0004] Japanese Patent Application Laid-Open No. 2002-192305 (paragraph 0025)

[0005] However, the conventional technology described above had the problem of generating wasted powder material that was not filled into the mold. The reason for this is as follows: First, since the filling port of the mold is formed facing upwards, the outlet from which the powder material flows out of the storage tank is formed facing downwards. Therefore, at the time the powder material is filled into the mold, the powder material inside the outlet is supported by the powder material already filled into the mold. As a result, when the outlet is separated from the filling port of the mold after filling is complete, the powder material inside the outlet, which has lost its support, falls onto the mold, and this amount of powder material is wasted. Of course, the amount of powder material wasted with each fall is small, but since powder material falls each time the mold is filled, a large amount of powder material is wasted overall.

[0006] This invention was made to solve the aforementioned problems of the conventional technology, and aims to provide a technology that makes it possible to fill the inside of a mold with powder or granular material without generating any wasted powder or granular material.

[0007] To solve the above-mentioned problems, the powder and granular material filling apparatus of the present invention employs the following configuration. In other words, a powder filling apparatus for filling the internal space of a mold with granular or powdery material, comprising: a storage tank in which the powder is stored; an outlet through which the powder flows out of the storage tank; a pressurized air supply unit for supplying pressurized air into the storage tank; a negative pressure generating unit for creating negative pressure inside the storage tank by sucking out the air inside the storage tank; and a control unit for controlling the operation of the pressurized air supply unit and the negative pressure generating unit, wherein the control unit operates the pressurized air supply unit when the outlet is in contact with the filling port of the mold, thereby blowing out the powder together with the pressurized air from the outlet to fill the inside of the mold with the powder, and then stops the operation of the pressurized air supply unit; and when the outlet separates from the filling port, the negative pressure generating unit is operated to suck the powder falling from the outlet into the storage tank together with the air outside the outlet.

[0008] Furthermore, the powder filling method corresponding to the powder filling apparatus of the present invention described above employs the following configuration. That is, in a powder filling method for filling the space inside a mold by releasing granular or powdery material stored in a storage tank from an outlet, the method is characterized by comprising the steps of: supplying pressurized air into the storage tank while the outlet is in contact with the filling port of the mold, thereby blowing out the powdery material from the outlet together with the pressurized air to fill the inside of the mold with the powdery material, and then stopping the supply of the pressurized air; and, after stopping the supply of the pressurized air, when the outlet separates from the filling port, sucking out the air in the storage tank, thereby drawing the powdery material falling from the outlet into the storage tank together with the air outside the outlet.

[0009] In the powder and granular material filling apparatus or method of the present invention, the outlet of the storage tank is brought into contact with the filling port of the mold, and pressurized air is supplied into the storage tank, causing the powder and granular material in the storage tank to be blown out from the outlet along with the pressurized air. In this way, the powder and granular material can be filled completely inside the mold. Furthermore, when separating the outlet of the storage tank from the filling port of the mold after filling with the powder and granular material, the air in the storage tank is sucked out, so that the powder and granular material that would otherwise fall from the outlet is also sucked into the storage tank along with the air. In this way, by simply adding a function to suck out the air in the storage tank, it is possible to prevent the powder and granular material from falling from the outlet of the storage tank and generating wasted powder and granular material when separating the outlet of the storage tank from the filling port of the mold.

[0010] Furthermore, in the powder and granular material filling apparatus of the present invention described above, the air in the storage tank may be started to be drawn out before the outlet is separated from the filling port of the mold, and only then may the outlet be separated from the filling port of the mold.

[0011] By creating a sufficiently negative pressure inside the storage tank and then separating the outlet from the filling port of the mold, air can be forcefully drawn in the moment of separation. Therefore, even if the capacity of the equipment used to draw air from the storage tank is small, it is possible to reliably prevent the generation of unnecessary powder and granular material.

[0012] Alternatively, in the powder and granular material filling apparatus of the present invention described above, the storage tank may be made open to the atmosphere, and the storage tank may be opened to the atmosphere before the outlet separates from the filling port of the mold. Then, when the outlet separates from the filling port of the mold, or after they separate, the suction of air from the storage tank may be started.

[0013] If the storage tank is opened to the atmosphere before the outlet separates from the filling port of the mold, the pressure inside the storage tank can prevent the powder or granular material inside from being blown out of the outlet. In addition, if the air in the storage tank is started to be drawn out at the moment the outlet separates from the filling port of the mold, or after they separate, even if the negative pressure generated inside the storage tank is excessive, that negative pressure will not be directly applied to the filling port of the mold. This makes it possible to prevent the powder or granular material filled in the mold from being sucked out from the filling port.

[0014] Furthermore, the clothes drying apparatus and powder / granular material filling method of the present invention described above can also be understood as the following molded product manufacturing apparatus or molded product manufacturing method. In other words, the present invention is a molded product manufacturing apparatus that manufactures a molded product made of granular or powdery material by filling a space inside a mold with the granular material and then solidifying the granular material inside the mold, comprising: a storage tank in which the granular material is stored; an outlet through which the granular material in the storage tank flows out of the storage tank; a moving unit that switches between a state in which the outlet is in contact with the filling port of the mold and a state in which the outlet is separated from the filling port by moving at least one of the mold or the outlet; a pressurized air supply unit that supplies pressurized air into the storage tank; a negative pressure generation unit that creates a negative pressure inside the storage tank by sucking out the air inside the storage tank; a solidification unit that solidifies the granular material inside the mold; and a control unit that controls the operation of the moving unit, the solidification unit, the pressurized air supply unit, and the negative pressure generation unit, wherein the control unit operates the moving unit to bring the outlet into contact with the filling port, The pressurized air supply unit is operated to blow out the granular material together with the pressurized air from the outlet, thereby filling the inside of the mold with the granular material. After the pressurized air supply unit is stopped, the operation of the pressurized air supply unit is stopped. After the operation of the pressurized air supply unit is stopped, the movement unit is operated to separate the outlet from the filling port. When separating the outlet from the filling port, the negative pressure generating unit is operated to suck the granular material falling from the outlet into the storage tank together with the air outside the outlet. Finally, the solidification unit is operated to solidify the granular material inside the mold.

[0015] Furthermore, a method for manufacturing a product corresponding to the product manufacturing apparatus of the present invention described above is a method for manufacturing a molded product by filling the space inside a mold with granular or powdery material stored in a storage tank by letting it flow out from an outlet, and then solidifying the granular material inside the mold, the method comprising: bringing the outlet into contact with the filling port of the mold; supplying pressurized air into the storage tank so that the granular material is blown out from the outlet together with the pressurized air to fill the inside of the mold with the granular material, and then stopping the supply of pressurized air; sucking the air from the storage tank while moving the outlet away from the filling port so that the granular material falling from the outlet is sucked into the storage tank together with the air outside the outlet; and solidifying the granular material inside the mold.

[0016] In the molded product manufacturing apparatus or molded product manufacturing method of the present invention, when filling a mold with powder or granular material to manufacture a molded product, the powder or granular material is filled using the same method as described above for the powder or granular material filling apparatus or powder or granular material filling method of the present invention, thereby preventing the generation of wasted powder or granular material.

[0017] This is an explanatory diagram showing the general structure of the sand core manufacturing apparatus 1 of this embodiment. This is a cross-sectional view showing the internal structure of the storage tank 23. This is an explanatory diagram showing the mechanism by which casting sand is held in the storage tank 23. This is a cross-sectional view showing the internal structure of the pressure cap 30. This is an explanatory diagram showing the shapes of the mold holding plate 13, the support column 14, the lifting plate 15, the lower burner 17, etc. This is an explanatory diagram showing the first half of the operation in which the sand core manufacturing apparatus 1 of this embodiment manufactures sand cores. This is an explanatory diagram showing the second half of the operation in which the sand core manufacturing apparatus 1 of this embodiment manufactures sand cores. This is an explanatory diagram showing why casting sand spills out of the storage tank 23 in the conventional method of raising the storage tank 23 without creating negative pressure inside the storage tank 23. This is an explanatory diagram showing why casting sand does not spill out of the outlet 25a when negative pressure is created inside the storage tank 23 when the storage tank 23 is raised. This is an explanatory diagram showing how the control unit 50 mounted on the sand core manufacturing apparatus 1 switches the switching valve 34 in accordance with the movement of the lifting cylinder 18, horizontal cylinder 28, push cylinder 32, and opening / closing shutter 22. This is an explanatory diagram showing how the modified sand core manufacturing apparatus 1 raises the storage tank 23 at the changed timing when the negative pressure generated by the suction device 36 is too large.

[0018] A. This Example: Below, as an example of the powder and granular material filling apparatus and molded product manufacturing apparatus of the present invention, a sand core manufacturing apparatus 1 that manufactures sand cores by solidifying casting sand into a predetermined shape using a mold will be described. Accordingly, the casting sand in this example corresponds to "powder and granular material" in the present invention, and the sand core in this example corresponds to "molded product" in the present invention.

[0019] Figure 1 is an explanatory diagram showing the general structure of the sand core manufacturing apparatus 1 of this embodiment. The sand core manufacturing apparatus 1 of this embodiment is formed by assembling various equipment onto a frame 2 formed by assembling steel frames. Focusing on the operation of the sand core manufacturing apparatus 1 when manufacturing sand cores, the sand core manufacturing apparatus 1 can be divided into a part that fills the inside of the mold with casting sand (casting sand filling section 20 in Figure 1), a part that solidifies the casting sand filled inside the mold (casting sand solidification section 10 in Figure 1), and a part that controls the operation of the casting sand solidification section 10 and the casting sand filling section 20 (control section 50 in Figure 1). In this embodiment, the casting sand filling section 20 and the control section 50 correspond to the "powder and granular material filling apparatus" in the present invention.

[0020] The casting sand solidification unit 10 includes an upper mold 11 assembled to a frame 2, a lower mold 12 that moves up and down below the upper mold 11, a mold holding plate 13 to which the lower mold 12 is attached, a lifting plate 15 that moves the mold holding plate 13 up and down, and a lifting cylinder 18 that moves the lifting plate 15 up and down. A lower burner 17 is mounted on the upper surface of the lifting plate 15, and support columns 14 are erected upward from the four corners of the lifting plate 15. A gas pipe (not shown) is connected to the lower burner 17, and a flame is formed upward by burning fuel gas supplied from the gas pipe.

[0021] As shown in Figure 1, when the lifting plate 15 is lowered to its lowest position, the mold holding plate 13 is resting on the support portion 2a that protrudes from the frame 2. However, when the lifting plate 15 is raised, the mold holding plate 13 is also raised along with the lifting plate 15 by being lifted by the support column 14, and as a result, the lower mold 12 attached to the upper surface of the mold holding plate 13 is pressed against the upper mold 11.

[0022] A recess 12a is formed on the upper surface of the lower mold 12, and a recess 11a is also formed on the lower surface of the upper mold 11. Therefore, when the lower mold 12 is raised and pressed against the upper mold 11, a space is formed between the upper surface of the lower mold 12 and the lower surface of the upper mold 11 by the recesses 12a and 11a. Furthermore, a filling port 11b is formed on the upper surface of the upper mold 11, and a filling passage 11c is formed from the filling port 11b through to the lower surface of the upper mold 11. Therefore, the space formed between the upper mold 11 and the lower mold 12 when the lower mold 12 is pressed against the upper mold 11 communicates with the filling port 11b via the filling passage 11c. In this embodiment, the upper mold 11 and the lower mold 12 correspond to the "molds" in the present invention.

[0023] Furthermore, an upper burner 16 is mounted above the upper mold 11. The upper burner 16 is attached to a carriage 27 that can move horizontally, and by moving the carriage 27, the upper burner 16 can be positioned directly above the upper mold 11. In addition, a gas pipe (not shown) is connected to the upper burner 16, and by burning the fuel gas supplied from the gas pipe, a flame is formed that points downward.

[0024] In the casting sand solidification section 10, casting sand is filled into the space between the upper mold 11 and the lower mold 12 using a method described later. The upper mold 11 and the lower mold 12 are then heated by the upper burner 16 and the lower burner 17. This process solidifies the casting sand in the space between the upper mold 11 and the lower mold 12, forming a sand core. In this embodiment, the casting sand is solidified into the filled shape by heating the upper mold 11 and the lower mold 12. However, the casting sand may be solidified by other methods as long as it can be solidified into the filled shape. For example, the casting sand may be solidified by compressing it under high pressure, or by applying a predetermined reaction gas that reacts with a material coated on the casting sand. Furthermore, the material to be filled into and solidified in the upper mold 11 and the lower mold 12 does not need to be casting sand; any granular or powdery material will do. Furthermore, the molded product manufactured does not necessarily have to be a sand core. In this embodiment, the upper burner 16 and the lower burner 17 correspond to the "solidification section" in the present invention.

[0025] The casting sand filling unit 20 includes a hopper 21 into which casting sand is fed, an opening / closing shutter 22 attached to the lower end of the hopper 21, a storage tank 23 for temporarily storing the casting sand to be filled, a carriage 27 on which the storage tank 23 is mounted and which is movable in the horizontal direction, and a horizontal cylinder 28 for moving the carriage 27. The storage tank 23 is attached to the carriage 27 in a state biased upward by a spring (not shown), and when force is applied from above it moves downward by a certain range, but when the force is removed it returns to its original position by the force of the spring. The carriage 27 is also equipped with the upper burner 16 mentioned above.

[0026] Furthermore, the casting sand filling section 20 is also equipped with a pressure cap 30, a pressing cylinder 32, a switching valve 34, and a suction device 36. Here, the suction device 36 is a cylindrical device with a Venturi-shaped central passage opening at both ends, and a supply nipple 36a is provided protruding from its side. When pressurized air is supplied from the supply nipple 36a, air at a flow rate greater than the supplied amount is blown out from the opening at one end of the suction device 36, and consequently, negative pressure is generated at the opening at the other end of the suction device 36. Note that it is sufficient for the suction device 36 to generate negative pressure by sucking in air at a certain flow rate or higher, and equipment such as a suction pump may be used. In this embodiment, the pressing cylinder 32 corresponds to the "moving section" in the present invention.

[0027] Furthermore, the switching valve 34 is a four-way valve having three input ports (not shown) and one output port (not shown), and by switching the switching valve 34, one of the three input ports is connected to the output port. The output port of the switching valve 34 is connected to the pressure cap 30 via a pressure hose 33. In addition, a pressure piping (not shown) that supplies pressurized air is connected to the first input port of the switching valve 34. Furthermore, the second input port of the three input ports is connected to the open end on the side where negative pressure is generated of the suction device 36 via a suction hose 35, and the remaining third input port is open to the atmosphere.

[0028] Furthermore, when the switching valve 34 is switched to connect the first input port (the input port to which pressurized air is supplied) to the output port, the pressurized air supplied from the first input port flows out from the output port, and this state will be referred to as the "air supply state" below. Also, when the switching valve 34 is switched to connect the second input port (the input port to which the negative pressure of the suction device 36 acts) to the output port, air is drawn in from the output port by the negative pressure acting on the second input port, and this state will be referred to as the "air suction state" below. Moreover, when the switching valve 34 is switched to connect the third input port (the input port open to the atmosphere) to the output port, the output port is also opened to the atmosphere, and this state will be referred to as the "atmospheric open state" below.

[0029] As will be described in detail later, the casting sand filling unit 20 operates as follows. First, the storage tank 23 is moved to a position directly below the hopper 21 by moving the carriage 27 with the horizontal cylinder 28. Figure 1 shows the state in which the storage tank 23 has been moved to a position directly below the hopper 21. After supplying a certain amount of casting sand from the hopper 21 to the storage tank 23 by opening the opening / closing shutter 22 in this state, the opening / closing shutter 22 is closed, and then the storage tank 23 is moved to a position directly above the upper mold 11 by moving the carriage 27 with the horizontal cylinder 28. The pressure cap 30 is mounted in a position directly above the moved storage tank 23. Subsequently, when the pressure cap 30 is lowered using the push cylinder 32, the storage tank 23 moves downward due to the pressure cap 30, and the lower surface of the storage tank 23 is pressed against the upper surface of the upper mold 11.

[0030] Next, the switching valve 34 is switched to the air supply state described above, thereby supplying pressurized air to the pressure cap 30. The pressurized air supplied to the pressure cap 30 flows into the storage tank 23 and, together with the casting sand in the storage tank 23, flows into the space between the upper mold 11 and the lower mold 12. As a result, the space between the upper mold 11 and the lower mold 12 is filled with casting sand. In this embodiment, since pressurized air is supplied to the storage tank 23 by switching the switching valve 34 to the air supply state, the switching valve 34 in this embodiment corresponds to the "pressurized air supply unit" in the present invention.

[0031] Once the casting sand has been filled, the pressurized air in the storage tank 23 and the pressure cap 30 is released to the atmosphere by switching the switching valve 34 to the atmospheric release state described above. In this embodiment, since the pressure inside the storage tank 23 and the pressure cap 30 is returned to atmospheric pressure by switching the switching valve 34 to the atmospheric release state, the switching valve 34 in this embodiment corresponds to the "atmospheric release section" in the present invention.

[0032] Then, once the pressure in the storage tank 23 and the pressure cap 30 returns to atmospheric pressure, the switching valve 34 is switched from an open-to-atmosphere state to an air-in-air state, thereby creating negative pressure in the storage tank 23 and the pressure cap 30, and then the pressure cap 30 is raised back to its original position. Consequently, the storage tank 23 also rises back to its original position. As will be explained in more detail later, creating negative pressure in the storage tank 23 and the pressure cap 30 when raising the pressure cap 30 and the storage tank 23 prevents the casting sand in the storage tank 23 from spilling out. In this embodiment, negative pressure is created in the storage tank 23 by switching the switching valve 34 to an air-supply state while air is being drawn in by the suction device 36. Therefore, in this embodiment, the switching valve 34 and the suction device 36 correspond to the "negative pressure generation unit" in the present invention.

[0033] The control unit 50 is a so-called microcomputer and controls the overall operation of the sand core manufacturing apparatus 1.

[0034] Figure 2 is a cross-sectional view showing the internal structure of the storage tank 23. As shown in the figure, the storage tank 23 has a cylindrical body 24 to which a disc-shaped bottom plate 25 is attached, and a casting sand supply port 24a is formed at the upper end of the body 24. A circular outlet 25a is formed in the center of the bottom plate 25, and above the outlet 25a, a larger diameter, disc-shaped storage plate 26 is attached parallel to the bottom plate 25. A gap 26a of a predetermined height is formed between the bottom plate 25 and the storage plate 26. In this way, the outlet 25a on the bottom of the storage tank 23 is actually always open, but the casting sand is retained in the storage tank 23 by the following mechanism.

[0035] Figure 3 is an explanatory diagram showing the mechanism by which casting sand is retained in the storage tank 23. When forming a mound of powdered material such as casting sand, the powdered material can be piled up as long as the slope of the mound is below a certain angle. However, if the angle of the slope exceeds a certain angle, the lower powdered material can no longer support the weight of the upper powdered material, and the slope collapses. This angle of the slope is called the "angle of repose," and it is known to take a value that is almost fixed depending on the size of each individual particle of the powdered material, the shape of the particles, the moisture content, and the surface properties. Figure 3(a) shows casting sand piled up at an angle of repose θ.

[0036] As long as the angle of the slope does not exceed the angle of repose θ, the casting sand can be piled up stably. As described above using Figure 2, a gap 26a is formed between the storage plate 26 and the bottom plate 25 in the storage tank 23, and by forming a slope less than or equal to the angle of repose θ, the casting sand can be stably held in the gap 26a. Figure 3(b) shows the state in which the casting sand is stably held in the gap 26a between the storage plate 26 and the bottom plate 25 in the storage tank 23. Furthermore, in order to prevent the angle of the slope of the casting sand formed in the gap 26a from exceeding the angle of repose θ, the outer diameter of the storage plate 26 should be made sufficiently large relative to the inner diameter of the outlet 25a, or the height of the gap 26a should be made sufficiently small. More specifically, the outer diameter D of the storage plate 26 and the height h of the gap 26a should be set such that tanθ > 2h / (D-d) relative to the angle of repose θ of the casting sand and the inner diameter d of the outlet 25a.

[0037] Figure 4 is a cross-sectional view showing the internal structure of the pressure cap 30. As shown, the inside of the pressure cap 30 is hollow, and the bottom surface of the pressure cap 30 is large and open. A through hole 30a is formed on the side of the pressure cap 30, and a nipple 31 protrudes outward from the position of the through hole 30a. The pressure hose 33 is connected to the nipple 31. The rod 32a of the pressing cylinder 32 is attached to the top surface of the pressure cap 30.

[0038] Figure 5 is an explanatory diagram showing the shapes of the mold holder plate 13, the support column 14, the lifting plate 15, and the lower burner 17. As described above using Figure 1, the mold holder plate 13 is a component to which the lower mold 12 is attached to the upper surface, and the lifting plate 15 is a component that moves up and down by the lifting cylinder 18. The mold holder plate 13 is supported by the support column 14 which is erected from the lifting plate 15, and the mold holder plate 13 moves up and down by moving the lifting plate 15 up and down.

[0039] As shown in Figure 5, the lifting plate 15 is a rectangular plate-shaped member made of iron, with a lower burner 17 attached to the center of its upper surface, and cylindrical iron support columns 14 erected at the four corners of the upper surface. Multiple burner nozzles 17a are attached to the upper surface of the lower burner 17, and by igniting the fuel gas flowing out from the burner nozzles 17a, a flame of fuel gas can be formed directed upward. In addition, the upper part of the support column 14 is processed to a smaller diameter to form a cylindrical guide portion 14a, and an annular contact surface 14b is formed where the outer diameter of the support column 14 changes to the outer diameter of the guide portion 14a.

[0040] The mold holder plate 13 is made of iron and has a rectangular plate-like member with a large-diameter circular central window 13a formed in the center. An annular peripheral wall 13b protrudes upward from the periphery of the central window 13a. Guide holes 13c are formed at the four corners of the mold holder plate 13. The inner diameter of the guide holes 13c is smaller than the outer diameter of the support column 14, but larger than the outer diameter of the guide portion 14a. Therefore, when the mold holder plate 13 is lowered from above the lifting plate 15 while inserting the guide portion 14a of the support column 14 through the four guide holes 13c, the lower surface of the mold holder plate 13 comes into contact with the contact surface 14b of the support column 14, making it possible to support the mold holder plate 13. As a result, the mold holding plate 13 is placed on the contact surface 14b of the support column 14 erected from the lifting plate 15, and is able to move vertically relative to the lifting plate 15 while being guided by the guide portion 14a. Rectangular projections 13d are also provided on the left and right sides of the mold holding plate 13. As shown in Figure 1, when the lifting cylinder 18 is lowered, the projections 13d are supported by the support portion 2a of the frame 2.

[0041] The sand core manufacturing apparatus 1 of this embodiment, having the structure described above, manufactures sand cores by filling the space formed by joining the upper mold 11 and the lower mold 12 with casting sand, and then heating the casting sand together with the upper mold 11 and the lower mold 12. In conventional methods of manufacturing sand cores in this way, a certain amount of casting sand spills out after filling, resulting in waste of casting sand. However, this problem is resolved in the sand core manufacturing apparatus 1 of this embodiment by improving upon the conventional method. Below, the operation of the sand core manufacturing apparatus 1 of this embodiment in manufacturing sand cores will be explained in detail, explaining why casting sand was wasted in the conventional method, and then explaining why casting sand is not wasted in this embodiment.

[0042] Figure 6 is an explanatory diagram showing the first half of the operation of the core sand manufacturing apparatus 1 of this embodiment for manufacturing core sand. Further, Figure 7 is an explanatory diagram showing the second half of the operation of the core sand manufacturing apparatus 1 of this embodiment for manufacturing core sand. In addition, in Figures 6 and 7, for the purpose of avoiding complication of the figures, illustration of the frame body 2, the control unit 50, etc. is omitted.

[0043] When manufacturing core sand, as shown in Figure 6(a), by moving the carriage 27 with the horizontal cylinder 28, the storage tank 23 is moved to a position directly below the hopper 21. Then, by opening the opening / closing shutter 22, the molding sand in the hopper 21 is supplied to the storage tank 23. The molding sand supplied to the storage tank 23 is held in the storage tank 23 in the state shown in Figure 3(b). Also, in the state shown in Figure 6(a), the lifting cylinder 18 is lowered to the lowest position, and the pressing cylinder 32 is raised to the highest position. Further, the switching valve 34 is switched to the above-described atmosphere release state.

[0044] Next, as shown in Figure 6(b), by operating the horizontal cylinder 28, the carriage 27 is moved so that the storage tank 23 is positioned directly above the upper mold 11. At this time, the storage tank 23 is positioned directly below the pressure cap 30. Subsequently, as shown in Figure 6(c), the lifting plate 15 is raised using the lifting cylinder 18, and thereby the mold holding plate 13 and the lower mold 12 are raised, so that the lower mold 12 is brought into contact with the lower surface of the upper mold 11. As a result, a space is formed between the upper mold 11 and the lower mold 12. Also, in parallel with the raising of the lifting cylinder 18, the pressure cap 30 is lowered with the pressing cylinder 32. As a result, the storage tank 23 is pushed down by the pressure cap 30, and the bottom surface of the storage tank 23 is pressed against the upper surface of the upper mold 11. Also, a flame of fuel gas is always formed by the lower burner 17. Therefore, when the lifting plate 15 pushes up the mold holding plate 13, the lower mold 12 attached to the mold holding plate 13 is in a state of being roasted from below by the lower burner 17 of the lifting plate 15.

[0045] Subsequently, when the switching valve 34 is switched to the aforementioned air supply state, pressurized air is supplied to the pressurized cap 30 and the storage tank 23 via the pressurized hose 33. In Figure 6(d), the flow of pressurized air supplied to the pressurized cap 30 and the storage tank 23 via the pressurized hose 33 is shown by thick dashed arrows. The pressurized air supplied to the storage tank 23 in this way is blown out together with the casting sand in the storage tank 23 from the outlet 25a (see Figure 2) that opens on the bottom surface of the storage tank 23. Then, it is filled into the space between the upper mold 11 and the lower mold 12 through the filling port 11b that opens on the upper surface of the upper mold 11 and the filling passage 11c. In addition, the upper mold 11 and the lower mold 12 have multiple vents that allow air to pass through but not casting sand, so that casting sand can be filled into every corner of the space between the upper mold 11 and the lower mold 12.

[0046] After filling the spaces inside the upper mold 11 and lower mold 12 with casting sand, it is then necessary to heat the upper mold 11 from above using the upper burner 16. To do this, the storage tank 23, which was pressed against the upper surface of the upper mold 11, needs to be raised back to its original position. However, since the pressure inside the storage tank 23 and pressure cap 30 is high due to the pressurized air, if the storage tank 23 is raised as is, the casting sand remaining inside the storage tank 23 will be blown out from the outlet 25a of the storage tank 23. Therefore, before raising the storage tank 23, the switching valve 34 is switched to the aforementioned open-to-atmosphere state to release the pressurized air inside the storage tank 23 and pressure cap 30 into the atmosphere, thereby reducing the pressure inside the storage tank 23 and pressure cap 30 to atmospheric pressure.

[0047] Conventionally, after thus reducing the pressures in the storage tank 23 and the pressure cap 30 to atmospheric pressure, the storage tank 23 was raised. However, in the sand core manufacturing apparatus 1 of the present embodiment, the switching valve 34 switched from the air supply state to the atmosphere release state is further switched to the air suction state. By doing so, the air in the storage tank 23 and the pressure cap 30 is sucked out by the negative pressure generated by the suction device 36, and the pressures in the storage tank 23 and the pressure cap 30 decrease. FIG. 7(a) shows how the air in the storage tank 23 and the pressure cap 30 is sucked out by the negative pressure generated by the suction device 36. In the present embodiment, a negative pressure is generated by supplying pressurized air to the suction device 36. However, if a negative pressure can be generated to suck out the air in the storage tank 23 and the pressure cap 30, a device other than the suction device 36 may be used to generate the negative pressure.

[0048] And after making the interiors of the storage tank 23 and the pressure cap 30 negative pressure, the pressure cap 30 is raised using the pressing cylinder 32. Then, the storage tank 23 that has been pushed downward by the pressure cap 30 also rises to its original position by the force of a spring (not shown). FIG. 7(b) shows a state where the storage tank 23 has risen to its original position. Also, after raising the storage tank 23, the switching valve 34 may be switched to the atmosphere release state. Thus, if the storage tank 23 is raised after making the interiors of the storage tank 23 and the pressure cap 30 negative pressure, it is possible to prevent the casting sand from spilling out from the outlet 25a of the storage tank 23 when the storage tank 23 is raised. The reason for this will be described in detail using another figure.

[0049] Once the storage tank 23 is raised back to its original position, the carriage 27 is moved using the horizontal cylinder 28, as shown in Figure 7(c), so that the upper burner 16 is directly above the upper mold 11. As a result, the upper mold 11 is heated from above by the upper burner 16, and the lower mold 12 is heated from below by the lower burner 17, thereby heating the casting sand filled in the space between the upper mold 11 and the lower mold 12. When the carriage 27 is moved so that the upper burner 16 is directly above the upper mold 11, the storage tank 23 mounted on the carriage 27 moves to a position directly below the hopper 21.

[0050] Then, after a predetermined time has elapsed while the upper mold 11 and lower mold 12 are heated by the upper burner 16 and lower burner 17, the casting sand between the upper mold 11 and lower mold 12 solidifies, forming a sand core. At this point, when the lifting plate 15 is lowered using the lifting cylinder 18, the mold holding plate 13 and the lower mold 12 also descend along with it, and the solidified casting sand (sand core) between the upper mold 11 and the lower mold 12 also descends together with the lower mold 12. As the lifting plate 15 is lowered further, the mold holding plate 13 and the lower mold 12 are supported by the support part 2a of the frame 2 (see Figure 1), and from there only the lifting plate 15 descends to the lowest position. Figure 7(d) shows the state in which the lifting plate 15 has descended to the lowest position. Once this state is reached, the sand core on top of the lower mold 12 can be removed. Then, after removing the sand core, return to Figure 6(a) and repeat the series of operations described above. In this way, a sand core can be manufactured.

[0051] In this embodiment, the sand core manufacturing apparatus 1 is configured such that, after supplying pressurized air to the storage tank 23 and filling the space between the upper mold 11 and the lower mold 12 with casting sand (see Figure 6(d)), the storage tank 23 is subjected to negative pressure before being raised (see Figure 7(a)), and then raised (see Figure 7(b)). The reason for creating negative pressure in the storage tank 23 before raising it is to prevent the casting sand in the storage tank 23 from spilling onto the upper mold 11 when the storage tank 23 is raised, thus preventing waste. To explain this, the following will explain why, in conventional methods where negative pressure is not created in the storage tank 23, the casting sand in the storage tank 23 spills out when the storage tank 23 is raised. Then, based on that reason, the reason why creating negative pressure in the storage tank 23 in this embodiment prevents the casting sand from spilling out will be explained.

[0052] Figure 8 is an explanatory diagram illustrating why casting sand spills out of the storage tank 23 in the conventional method of raising the storage tank 23 without creating negative pressure inside the storage tank 23. Figure 8(a) shows the inside of the storage tank 23 after casting sand has been filled into the space inside the upper mold 11 and the lower mold 12. It is assumed that the pressure inside the storage tank 23 has already been returned to atmospheric pressure. As shown in the figure, after filling with casting sand, the area from below the storage plate 26 to the filling passage 11c of the upper mold 11 is also filled with casting sand from the storage tank 23. At this time, the casting sand located below the storage plate 26 is supported by the casting sand filled in the filling passage 11c.

[0053] Therefore, when the storage tank 23 is raised from this state, as shown in Figure 8(b), the casting sand that was below the storage plate 26 falls down and forms a small mound on the filling passage 11c of the upper molding die 11. Also, inside the storage tank 23, the casting sand is held in place by forming a slope at the angle of repose around the outlet 25a (see Figure 3). Therefore, in the conventional method, each time the storage tank 23 is raised after filling it with casting sand, the casting sand below the storage plate 26 spills out from the outlet 25a, resulting in the waste of this casting sand. In contrast, in the sand core manufacturing apparatus 1 of this embodiment, after filling with casting sand, the inside of the storage tank 23 is made negatively pressurized before raising the storage tank 23, which prevents the casting sand from spilling out from the outlet 25a.

[0054] Figure 9 is an explanatory diagram illustrating why casting sand can be prevented from spilling out of the outlet 25a by creating negative pressure inside the storage tank 23 before raising the storage tank 23. Figure 9(a) shows the state after casting sand has been filled inside the upper mold 11 and the lower mold 12, and the inside of the storage tank 23 has been created to negative pressure. Immediately after filling with casting sand, the bottom plate 25 of the storage tank 23 is pressed against the upper surface of the upper mold 11, so by sucking out the air inside the storage tank 23, the pressure inside the storage tank 23 can be reduced to negative pressure. In the sand core manufacturing apparatus 1 of this embodiment, negative pressure is created inside the storage tank 23 by switching the switching valve 34 to the air suction state.

[0055] In this state, when the storage tank 23 is raised, the moment the bottom plate 25 of the storage tank 23 separates from the upper surface of the upper mold 11, the air surrounding the storage tank 23 flows forcefully into the storage tank 23 through the gap between the bottom plate 25 and the upper surface of the upper mold 11. The thick dashed arrows shown in Figure 9(b) indicate the flow of air flowing into the storage tank 23. As illustrated, the incoming air enters the storage tank 23 from the outlet 25a of the bottom plate 25 (see Figure 2), then collides with the storage plate 26, changes direction, and passes through the gap 26a (see Figure 2) between the bottom plate 25 and the storage plate 26. As a result, the casting sand that was located below the storage plate 26 is sucked into the storage tank 23 by this airflow.

[0056] Furthermore, when air flows in, the negative pressure inside the storage tank 23 decreases, which reduces the force of the incoming air. Moreover, after switching the switching valve 34 to the open-to-atmosphere state, no more air flows in. However, the casting sand around the outlet 25a is drawn in by the incoming air, forming a slope with a gentler incline than the angle of repose. As a result, as shown in Figure 9(c), the casting sand can be stably retained inside the storage tank 23 even when the air inflow stops. Consequently, even when the storage tank 23 is raised, it is possible to prevent the casting sand from spilling out of the outlet 25a.

[0057] Furthermore, as described above, since the air inside the storage tank 23 is sucked out before raising the storage tank 23, even if the air flow rate sucked in by the suction device 36 is small, if given some time, the storage tank 23 can be made into a negative pressure up to the minimum pressure that the suction device 36 can generate. Then, by raising the storage tank 23, even when using a suction device 36 with a small air flow rate, air can be forcefully sucked in from the outlet 25a of the storage tank 23, and as a result, casting sand spilling out from the outlet 25a can be reliably collected. Of course, if the suction device 36 is capable of sucking in a sufficient flow rate of air, or if a suction pump capable of sucking in a sufficient flow rate of air is used to generate negative pressure, the air inside the storage tank 23 and the pressure cap 30 may be sucked out at the same time as raising the storage tank 23, or immediately after raising the storage tank 23.

[0058] In the sand core manufacturing apparatus 1 of this embodiment, after filling with casting sand, the inside of the storage tank 23 is made negatively pressurized before raising the storage tank 23. This mechanism makes it possible to recover casting sand that would otherwise spill out into the storage tank 23. This is achieved by the control unit 50 appropriately switching the switching valve 34 in accordance with the movement of the lifting cylinder 18, the horizontal cylinder 28, and the push cylinder 32. Therefore, the control by which the control unit 50 switches the switching valve 34 in accordance with the movement of the lifting cylinder 18 and the like will be described below.

[0059] Figure 10 is an explanatory diagram showing how the control unit 50 mounted on the sand core manufacturing apparatus 1 of this embodiment appropriately switches the switching valve 34 in accordance with the movements of the lifting cylinder 18, horizontal cylinder 28, push cylinder 32, and opening / closing shutter 22. In the figure, the movements of the lifting cylinder 18, horizontal cylinder 28, push cylinder 32, and opening / closing shutter 22 are shown as time progresses on the horizontal axis. Furthermore, the switching of the switching valve 34 in accordance with these movements is shown above. Here, the opening and closing operation of the opening / closing shutter 22 is explained as being controlled by the control unit 50, but the opening / closing shutter 22 may be opened and closed by the movement of the carriage 27 when the control unit 50 operates the lifting cylinder 18 to move the carriage 27.

[0060] As described above using Figures 6 and 7, in order to manufacture sand cores with the sand core manufacturing apparatus 1, it is necessary to fill the insides of the upper mold 11 and the lower mold 12 with casting sand (corresponding to Figures 6(a) to (d)). This operation can be expressed using the movements of the lifting cylinder 18, the horizontal cylinder 28, the push cylinder 32, and the opening / closing shutter 22 as follows. First, the opening / closing shutter 22 is opened for a predetermined time, then the horizontal cylinder 28 is moved forward, followed by raising the lifting cylinder 18 and lowering the push cylinder 32. After that, the switching valve 34 is switched from an open-to-atmosphere state to an air supply state. By doing so, casting sand is filled inside the upper mold 11 and the lower mold 12.

[0061] After filling with casting sand, it is necessary to heat and solidify the casting sand (corresponding to Figure 7(c)). Before that, however, it is necessary to create negative pressure inside the storage tank 23, raise the storage tank 23 (corresponding to Figures 7(a) and (b)), and then retract the carriage 27 to its original position. This operation can be described using the movements of the lifting cylinder 18, horizontal cylinder 28, push cylinder 32, and opening / closing shutter 22 as follows: First, the switching valve 34 is switched from an air supply state to an open-to-atmosphere state to return the pressure inside the storage tank 23 and pressure cap 30 to atmospheric pressure. Then, the switching valve 34 is switched from an open-to-atmosphere state to an air intake state to create negative pressure inside the storage tank 23 and pressure cap 30. After that, the push cylinder 32 is raised, and then the horizontal cylinder 28 is retracted. In this way, the casting sand in the upper mold 11 and the lower mold 12 is heated from above and below by the upper burner 16 and the lower burner 17, and after a predetermined time, the casting sand solidifies and a sand core is formed. Then, the lifting cylinder 18 is lowered to remove the sand core. Note that some or all of the above series of controls performed by the control unit 50 in this embodiment correspond to the "powder and granular material filling method" or "molded product manufacturing method" in the present invention.

[0062] B. Modification: In the sand core manufacturing apparatus 1 of the above embodiment, in order to reliably recover the casting sand, the magnitude of the negative pressure that the suction device 36 can generate is considered more important than the flow rate of air that the suction device 36 can suck up. This is because, even if the flow rate of air that the suction device 36 can suck up is small, if the negative pressure that can be generated is large, the pressure inside the storage tank 23 can be sufficiently reduced by sucking out the air inside the storage tank 23 over a short period of time, making it possible to reliably recover the casting sand. Therefore, it is desirable to use a suction device 36 that can generate a slightly larger negative pressure. However, if the negative pressure generated by the suction device 36 is too large, there is a risk that when the inside of the storage tank 23 is made into a negative pressure, the casting sand filled in the space between the upper mold 11 and the lower mold 12 will be sucked out by the negative pressure inside the storage tank 23.

[0063] Furthermore, while the sand core manufacturing apparatus 1 can produce various types of sand cores by changing the mold used and the type of casting sand, even when the same negative pressure is applied, the filling casting sand may or may not be sucked out depending on the type of sand core being manufactured. As a result, it becomes necessary to change the negative pressure generated by replacing the suction device 36 each time the type of sand core being manufactured is switched, which may reduce manufacturing efficiency.

[0064] However, by changing the timing of raising the storage tank 23 after filling with casting sand, it is possible to prevent the filled casting sand from being sucked out even if the negative pressure generated by the suction device 36 is too large.

[0065] Figure 11 is an explanatory diagram showing how the modified sand core manufacturing apparatus 1 raises the storage tank 23 at a changed timing when the negative pressure generated by the suction device 36 is too large. Figure 11(a) shows the state immediately after filling with casting sand. At this stage, the inside of the storage tank 23 is still pressurized, so if the storage tank 23 is raised, the casting sand inside the storage tank 23 will blow out through the gap created between the bottom plate 25 of the storage tank 23 and the upper molding die 11. Therefore, the storage tank 23 cannot be raised yet.

[0066] However, after switching the switching valve 34 to the open-to-atmosphere state and reducing the pressure inside the storage tank 23 to atmospheric pressure, raising the storage tank 23 will only cause the casting sand inside the outlet 25a to spill out, and there is no risk of the casting sand inside the storage tank 23 being blown out. Also, immediately after switching the switching valve 34 to the air-suction state and starting to suck air with the suction device 36, the negative pressure inside the storage tank 23 is not yet considered to be very large. Therefore, it is considered possible to reduce the amount of casting sand spilling out from the outlet 25a by raising the storage tank 23 at this stage.

[0067] Therefore, in the modified sand core manufacturing apparatus 1, as shown in Figure 11(b), the storage tank 23 is raised when the pressure inside the storage tank 23 reaches atmospheric pressure, or before the negative pressure becomes large. In this way, by separating the bottom plate 25 of the storage tank 23 from the upper mold 11 before the negative pressure inside the storage tank 23 becomes large, even if the negative pressure inside the storage tank 23 increases afterward, air is simply drawn in through the gap between the bottom plate 25 and the upper mold 11, and a large negative pressure is not applied to the filling passage 11c of the upper mold 11. For this reason, even if the negative pressure generated by the suction device 36 is too large, the filled casting sand will not be sucked out. Thus, in the modified sand core manufacturing apparatus 1, even if the negative pressure that can be generated by the suction device 36 becomes excessive due to switching the type of sand core to be manufactured, it is possible to continue manufacturing sand cores without changing the negative pressure generated by the suction device 36.

[0068] Although the sand core manufacturing apparatus 1 of this embodiment and its modified form has been described above, the present invention is not limited to the above embodiment and its modified form, and can be implemented in various forms without departing from the spirit of the invention.

[0069] For example, in the sand core manufacturing apparatus 1 of this embodiment and its modified form described above, the bottom plate 25 of the storage tank 23 is pressed against the upper surface of the upper mold 11 by lowering the storage tank 23. However, the upper mold 11 and the lower mold 12 may be raised to press the upper surface of the upper mold 11 against the bottom plate 25 of the storage tank 23, and then casting sand may be filled into the interiors of the upper mold 11 and the lower mold 12.

[0070] 1...Sand core manufacturing device, 2...Frame, 2a...Support part, 10...Casting sand solidification part, 11...Upper molding die, 11a...Recess, 11b...Filling port, 11c...Filling passage, 12...Lower molding die, 12a...Recess, 13...Molding die holding plate, 13a...Central window, 13b...Peripheral wall, 13c...Guide hole, 13d...Protrusion, 14...Support column, 14a...Guide part, 14b...Contact surface, 15...Lifting plate, 16...Upper burner, 17...Lower burner, 17a...Burner nozzle, 18...Lifting cylinder, 20...Casting sand filling part, 21...Hopper, 22...Opening / closing shutter, 23...Storage tank, 24...Main body, 24a...Supply port, 25...Bottom plate, 25a...Outlet, 26...Storage plate, 26a...Gap, 27...Carriage, 28...Horizontal cylinder, 30...Pressure cap, 30a...Through hole, 31...Nipple, 32...Depression cylinder, 32a...Rod, 33...Pressure hose, 34...Switching valve, 35...Suction hose, 36...Suction device, 36a...Supply nipple, 50...Control unit.

Claims

1. A powder filling apparatus for filling the internal space of a mold with granular or powdery material, comprising: a storage tank in which the powdery material is stored; an outlet through which the powdery material in the storage tank flows out; a pressurized air supply unit for supplying pressurized air into the storage tank; a negative pressure generating unit for creating negative pressure inside the storage tank by sucking out the air inside the storage tank; and a control unit for controlling the operation of the pressurized air supply unit and the negative pressure generating unit, wherein the control unit operates the pressurized air supply unit when the outlet is in contact with the filling port of the mold, thereby blowing out the powdery material together with the pressurized air from the outlet to fill the inside of the mold with the powdery material, and then stops the operation of the pressurized air supply unit; and when the outlet separates from the filling port, the negative pressure generating unit is operated to suck the powdery material falling from the outlet into the storage tank together with the air outside the outlet.

2. A powder and granular material filling apparatus according to claim 1, characterized in that the control unit operates the negative pressure generating unit after stopping the operation of the pressurized air supply unit, and before the outlet separates from the filling port of the mold.

3. A powder and granular material filling apparatus according to claim 1, comprising an atmospheric vent that opens the storage tank to the atmosphere, wherein the control unit operates the atmospheric vent from the time before the outlet separates from the filling port of the mold after stopping the operation of the pressurized air supply unit, and operates the negative pressure generating unit from the time when the outlet separates from the filling port of the mold or after the separation.

4. A molded product manufacturing apparatus for manufacturing a molded product by filling a mold with granular or powdery material into the internal space of a mold and then solidifying the granular material inside the mold, comprising: a storage tank in which the granular material is stored; an outlet through which the granular material in the storage tank flows out of the storage tank; a moving unit that switches between a state in which the outlet is in contact with the filling port of the mold and a state in which the outlet is separated from the filling port by moving at least one of the mold or the outlet; a pressurized air supply unit that supplies pressurized air into the storage tank; a negative pressure generating unit that creates a negative pressure inside the storage tank by sucking out the air inside the storage tank; a solidification unit that solidifies the granular material inside the mold; and a control unit that controls the operation of the moving unit, the solidification unit, the pressurized air supply unit, and the negative pressure generating unit, wherein the control unit operates the moving unit to bring the outlet into contact with the filling port, A molded product manufacturing apparatus characterized by operating the pressurized air supply unit to blow out the powder and granular material from the outlet together with the pressurized air, thereby filling the inside of the mold with the powder and granular material, then stopping the operation of the pressurized air supply unit, operating the moving unit to separate the outlet from the filling port, and when separating the outlet from the filling port, operating the negative pressure generating unit to suck the powder and granular material falling from the outlet together with the air outside the outlet into the storage tank, and then operating the solidification unit to solidify the powder and granular material inside the mold.

5. A method for filling a mold with granular or powdery material stored in a storage tank, wherein the granular or powdery material stored in the storage tank is discharged from an outlet to fill the internal space of the mold, comprising the steps of: supplying pressurized air into the storage tank while the outlet is in contact with the filling port of the mold, thereby blowing out the granular material from the outlet together with the pressurized air to fill the inside of the mold with the granular material, and then stopping the supply of pressurized air; and, after stopping the supply of pressurized air, when the outlet separates from the filling port, sucking out the air in the storage tank, thereby drawing the granular material falling from the outlet into the storage tank together with the air outside the outlet.

6. A method for manufacturing a molded product comprising: filling the space inside a mold by discharging granular or powdery material stored in a storage tank from an outlet, and then solidifying the granular material inside the mold, the method comprising: bringing the outlet into contact with the filling port of the mold; supplying pressurized air into the storage tank to blow out the granular material from the outlet together with the pressurized air and fill the inside of the mold with the granular material, and then stopping the supply of pressurized air; sucking the air from the storage tank while moving the outlet away from the filling port, thereby drawing the granular material falling from the outlet into the storage tank together with the air outside the outlet; and solidifying the granular material inside the mold.

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