JP2014515313A - Core sand filling apparatus and core sand filling method in core molding machine - Google Patents

Abstract

  A core type, a blow head that is disposed below the core type so as to be movable up and down relative to the core type, and is divided into a sand blowing chamber and a sand storage chamber that communicate with each other; A compressed air supply unit that communicates with the sand blowing chamber and supplies compressed air to the sand blowing chamber; an aeration air supply unit that communicates with the sand blowing chamber and supplies aeration air to the sand blowing chamber; An exhaust unit that communicates with the sand blowing chamber and exhausts compressed air remaining in the sand blowing chamber; a sand feed air supply unit that communicates with the sand storage chamber and supplies compressed air to the sand storage chamber; It comprises.

Description

  Various aspects and embodiments of the present invention relate to a core sand filling apparatus and a core sand filling method for filling core sand into a core mold in a core molding machine.

  Conventionally, a so-called top blow type core molding machine is known in which a blow head is disposed above a core mold and core sand is blown from above the core mold toward a core mold below. (For example, refer to Patent Document 1).

Japanese Patent Publication No.47-13179

  However, in the case of a top blow type core molding machine as in Patent Document 1, since the blow head is disposed above the core mold and the core sand hopper is further disposed thereon, the height of the apparatus is high. Therefore, there is a problem that the apparatus becomes large. For this reason, when trying to reduce the height of the device as much as possible and to reduce the size of the device, a blow head is disposed below the core mold, and core sand is moved from the bottom of the core mold toward the upper core mold. It is conceivable to employ a so-called under blow type core molding machine. However, in the case of the underblow type core molding machine, the core sand is blown from the lower side of the core type toward the upper core type, so that it blows against gravity. For this reason, there exists a problem that the filling property of core sand is inferior compared with a top blow type core molding machine.

  In this technical field, a core sand filling device and a core sand filling method in a core molding machine that can reduce the size of the apparatus and improve the filling property of the core sand are desired.

  A core sand filling apparatus according to one aspect of the present invention is a core sand filling apparatus in an under-blow type core molding machine that blows core sand from below a core mold toward an upper core mold. The core mold, and a blow head that is disposed below the core mold so as to be movable up and down relative to the core mold, and is divided into a sand blowing chamber and a sand storage chamber that communicate with each other. A compressed air supply unit that communicates with the sand blowing chamber and that supplies compressed air for blowing core sand into the core mold into the sand blowing chamber, and communicates with the sand blowing chamber. And aeration air supply unit for supplying aeration air for floating and fluidizing core sand into the sand blowing chamber, and compressed air that is communicated with the sand blowing chamber and remains in the sand blowing chamber An exhaust unit for exhausting, and a sand feed air supply unit that communicates with the sand storage chamber and supplies compressed air for feeding core sand into the sand blowing chamber into the sand storage chamber. It has.

  In one embodiment, a pressure sensor for measuring the pressure in the blow head may be attached to the sand blowing chamber.

  In one embodiment, a sand blowing nozzle may be provided to protrude from the lower end of the plate at the lower end of a sand blowing hole drilled in a plate attached to the upper end of the sand blowing chamber.

  A core sand filling method according to another aspect of the present invention is a core sand filling method in a core molding machine using the core sand filling device in the core molding machine according to claim 1, A step of bringing the core mold into contact with the sand blowing chamber, a step of operating the aeration air supply unit to float and fluidize core sand in the sand blowing chamber, a step of operating the compressed air supply unit, and blowing the sand Blowing the core sand into the core mold, operating the sand feeding air supply unit, feeding the core sand into the sand blowing chamber, the aeration air supply unit, and A step of stopping the operation of the compressed air supply unit, a step of operating the exhaust unit, exhausting the compressed air remaining in the sand blowing chamber, and a step of stopping the operation of the sand feed air supply unit; A.

  In one embodiment, the aeration air supply unit, the compressed air supply unit, and the sand feed air supply unit may have the same operating pressure.

  In one embodiment, the operating pressure of the sand feed air supply unit may be higher than the operating pressures of the aeration air supply unit and the compressed air supply unit.

  A core sand filling apparatus according to one aspect of the present invention is a core sand filling apparatus in an under-blow type core molding machine that blows core sand from below a core mold toward an upper core mold. The core mold, and a blow head that is disposed below the core mold so as to be movable up and down relative to the core mold, and is divided into a sand blowing chamber and a sand storage chamber that communicate with each other. A compressed air supply unit that communicates with the sand blowing chamber and that supplies compressed air for blowing core sand into the core mold into the sand blowing chamber, and communicates with the sand blowing chamber. And aeration air supply unit for supplying aeration air for floating and fluidizing core sand into the sand blowing chamber, and compressed air that is communicated with the sand blowing chamber and remains in the sand blowing chamber An exhaust unit for exhausting, and a sand feed air supply unit that communicates with the sand storage chamber and supplies compressed air for feeding core sand into the sand blowing chamber into the sand storage chamber. Since the apparatus is provided, there are various effects such as reduction in size of the apparatus and improvement of core sand filling properties.

It is a front sectional view showing an embodiment of the present invention. It is an AA arrow line view in FIG. It is a BB arrow line view in FIG. It is CC arrow line view in FIG. It is a flowchart which shows operation | movement of the core sand filling apparatus in a core molding machine. It is front sectional drawing which shows 2nd Embodiment of this invention. FIG. 7 is a DD arrow view in FIG. 6. In 1st Embodiment, it is a fragmentary front sectional view which shows the state in which the air layer was made between the upper surface of the core sand in the sand blowing chamber, and the lower end of a plate. In 2nd Embodiment, it is a fragmentary front sectional view which shows the state in which the air layer was made between the upper surface of the core sand in the sand blowing chamber, and the lower end of a plate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, an example is shown in which a shell core molding machine that molds a shell core by blowing and filling resin-coated sand into a heated mold is shown. Moreover, this embodiment shows the example using the underblow type core molding machine which blows core sand toward the upper core type from the lower side of the core type. The drawings mainly show a core sand filling device in a core molding machine. For this reason, illustration of components of the core molding machine other than the core sand filling device is omitted.

  In FIG. 1, a blow head 2 that can be moved up and down relative to the core mold 1 is disposed below the matched core mold 1 (in this embodiment, a mold). . The blow head 2 is connected to a lift cylinder (not shown). In this embodiment, the blow head 2 is lifted and lowered with respect to the core mold 1 arranged at a predetermined position.

  The blow head 2 is divided into two chambers, an adjacent sand blowing chamber 4 and a sand storage chamber 5, by a partition plate 3 provided at an intermediate position. Thereby, the blowing chamber 4 and the sand storage chamber 5 are arrange | positioned in a substantially horizontal direction. A plate 4a that comes into close contact with the core mold 1 is attached to the upper end of the sand blowing chamber 4, and the core sand (not shown) in the sand blowing chamber 4 is attached to the plate 4a. A sand blowing hole 4b for blowing into the cavity 1a of the core mold 1 is formed. The core mold 1 has a vent hole (not shown) communicating with the cavity 1a.

  Moreover, the opening part 3a (refer FIG. 2) is provided in the low-order both ends of the said partition plate 3, and the said sand blowing chamber 4 and the sand storage chamber 5 are mutually connected via this opening part 3a. As shown in FIG. 3, the sand storage chamber 5 is bifurcated and divided into a left chamber 5a and a right chamber 5b. The left chamber 5a and the right chamber 5b are communicated with each other at the upper portion. . The left chamber 5a and the right chamber 5b are partially inclined at the bottom (see FIG. 1). Further, the upper surface of the ceiling plate 5 d of the sand storage chamber 5 is positioned lower than the upper surface of the plate 4 a in the sand blowing chamber 4.

  An opening 3b is provided at the lower center of the partition plate 3, and compressed air for blowing the core sand in the sand blowing chamber 4 into the core mold 1 outside the opening 3b. Is connected to a compressed air supply unit 6 for supplying the air into the sand blowing chamber 4. A compressed air introduction pipe 6b in the compressed air supply unit 6 communicates with the sand blowing chamber 4 through the opening 3b. A bronze sintered body 6a is attached to the tip of the compressed air introduction pipe 6b. The compressed air introduction pipe 6b is disposed between the left chamber 5a and the right chamber 5b in the sand storage chamber 5, that is, between the two chambers (see FIGS. 3 and 4). The base end of the compressed air introduction pipe 6b is communicated with a compressed air source (not shown) through an open / close valve (not shown).

  An aeration air supply unit 7 for supplying aeration air that floats and fluidizes core sand in the sand blowing chamber 4 into the sand blowing chamber 4 is mounted on the side wall of the sand blowing chamber 4. A bronze sintered body (not shown) is attached to the tip of the aeration air supply unit 7, and the aeration air supply unit 7 enters the sand blowing chamber 4 through the sintered body. It is communicated. The proximal end of the aeration air supply unit 7 communicates with a compressed air source (not shown) through an open / close valve (not shown).

  An exhaust unit 8 for exhausting compressed air remaining in the sand blowing chamber 4 is mounted on the side wall of the sand blowing chamber 4 above the aeration air supply unit 7. A bronze sintered body (not shown) is attached to the tip of the exhaust part 8, and the exhaust part 8 communicates with the sand blowing chamber 4 through the sintered body. . The base end of the exhaust part 8 is communicated with an open / close valve (not shown).

  A pressure sensor 9 for measuring the pressure in the blow head 2 is mounted on the side wall of the sand blowing chamber 4 below the aeration air supply unit 7. Further, compressed air for sending core sand in the sand storage chamber 5 into the sand blowing chamber 4 is stored in the upper portion of the side walls of the left chamber 5a and the right chamber 5b in the sand storage chamber 5. A sand feed air supply unit 10 for supplying the chamber 5 is mounted. A bronze sintered body (not shown) is attached to the tip of the sand feed air supply unit 10, and the sand feed air supply unit 10 is connected to the sand storage chamber via the sintered body. 5 is communicated. The base end of the sand feed air supply unit 10 is communicated with a compressed air source (not shown) through an open / close valve (not shown).

  Further, a plate material 5c is attached to the upper end of the sand storage chamber 5, and a sand storage hole 5e is formed in the ceiling plate 5d and the plate material 5c of the sand storage chamber 5. A flange 11 having a through hole 11a is disposed above the plate member 5c, and a sand supply pipe 12 communicating with the through hole 11a is fixed to the upper end of the flange 11. Yes. The sand supply pipe 12 communicates with a sand hopper (not shown) through a sand supply hose (not shown).

  An open / close gate 13 having a communication hole 13a is disposed between the plate member 5c and the flange 11. The open / close gate 13 is opened and closed by a cylinder (not shown) (moves left and right). It has become. When the blow head 2 is lowered by the lifting cylinder (not shown), the plate material 5c, the open / close gate 13, the flange 11 and the sand supply pipe 12 are all lowered.

  The operation of the core sand filling device in the core molding machine configured as described above will be described. FIG. 5 is a flowchart showing the operation of the core sand filling device (core sand filling method). As shown in FIG. 5, first, a step of closely contacting the core mold 1 and the sand blowing chamber 4 is performed (S10). First, the matched core mold 1 is placed at a predetermined position. Then, the open / close gate 13 is closed by a cylinder (not shown). Thereafter, the blow head 2 is raised by an elevating cylinder (not shown) to obtain the state shown in FIG. In the state of FIG. 1, the core mold 1 and the plate 4a are in close contact. The sand filling hole 5e is closed by an open / close gate 13, and the blow head 2 is sealed. Each of the sand blowing chamber 4 and the sand storage chamber 5 contains a necessary amount of core sand (not shown).

  Next, in the state of FIG. 1, an on-off valve (not shown) is opened, and the aeration air supply unit 7 is operated (S12). Then, compressed air (that is, aeration air) is ejected from the sintered body attached to the tip of the aeration air supply unit 7, and the core sand in the sand blowing chamber 4 is floated and fluidized. And after predetermined time progress, the on-off valve which is not illustrated is opened and the compressed air supply part 6 is operated (S14). Then, compressed air is ejected from the sintered body 6a attached to the tip of the compressed air introduction pipe 6b, and the core sand in the sand blowing chamber 4 is blown into the cavity 1a of the core mold 1 through the sand blowing hole 4b. It is. At this time, the compressed air blown into the cavity 1a together with the core sand is exhausted from the vent hole (not shown).

  And after predetermined time progress, the on-off valve which is not shown in figure is opened and the sand feed air supply part 10 is operated (S16). Then, compressed air (that is, sand feed air) is ejected from the sintered body attached to the tip of the sand feed air supply unit 10, and core sand in the sand storage chamber 5 is sent into the sand blowing chamber 4. Then, after a predetermined time has elapsed from the start of the operation of the sand feed air supply unit 10, an on-off valve (not shown) is closed and the operations of the aeration air supply unit 7 and the compressed air supply unit 6 are stopped (S18). At this time, since the core sand in the sand blowing chamber 4 and the sand storage chamber 5 is subjected to pressure to move into the cavity 1a of the core mold 1, the core sand filled in the cavity 1a is used. Will not fall.

  Then, after a predetermined time has elapsed since the aeration air supply unit 7 and the compressed air supply unit 6 have stopped operating, an unillustrated on-off valve is opened and the exhaust unit 8 is operated (S20). Then, the compressed air remaining in the sand blowing chamber 4 is exhausted. At this time, since the compressed air from the sand feed air supply unit 10 can be discharged from the exhaust unit 8, the core sand in the sand storage chamber 5 is moved into the sand blowing chamber 4 along the flow. The sand blowing chamber 4 is filled with core sand.

  Then, after a lapse of a predetermined time from the start of the operation of the exhaust unit 8, the on-off valve (not shown) is closed, and the operation of the sand feed air supply unit 10 is stopped (S22). Thereafter, when the pressure sensor 9 measures that the pressure in the blow head 2 is zero, the blow head 2 is lowered by a lift cylinder (not shown) to separate the core mold 1 and the blow head 2 (S24). Then, an on-off valve (not shown) communicating with the exhaust unit 8 is closed.

  Then, after the core mold 1 is horizontally moved to another position, the mold is opened and the core is taken out. Then, the open / close gate 13 is opened by a cylinder (not shown). Thereby, the core sand in the sand hopper is supplied into the sand storage chamber 5 through the sand supply pipe 12, the through hole 11a, the communication hole 13a, and the sand storage hole 5e (S26).

  In the above-described embodiment, the operating pressures of the aeration air supply unit 7, the compressed air supply unit 6, and the sand feed air supply unit 10 are the same pressure. When the pressure is the same, there is an advantage that the amount of air consumption can be reduced.

  In one embodiment, the aeration air supply unit 7, the compressed air supply unit 6, and the sand feed air supply unit 10 have the same operating pressure as described above. However, the present invention is not limited to this, and the sand feed air supply is not limited thereto. You may make it make the working pressure of the part 10 higher than the working pressure of the aeration air supply part 7 and the compressed air supply part 6. FIG. In this case, due to the pressure difference between the operating pressure of the sand feed air supply unit 10 and the operating pressure of the aeration air supply unit 7 and the compressed air supply unit 6, the core sand in the sand storage chamber 5 is smoothly and continuously sanded. There is an advantage that it is fed into the blowing chamber 4. In this case, the operating pressure of the aeration air supply unit 7 and the compressed air supply unit 6 may be higher than the operating pressure of the aeration air supply unit 7 and the compressed air supply unit 6. Either the same pressure or the same pressure may be used.

  In one embodiment, a blow head 2 divided into a sand blowing chamber 4 and a sand storage chamber 5 communicating with each other is disposed below the core mold 1 so as to be movable up and down relative to the core mold 1. It has been configured. Thereby, compared with a top blow type core molding machine, since the apparatus width of a perpendicular direction can be shortened, there exists an effect that an apparatus can be reduced in size. Furthermore, by arranging the sand blowing chamber 4 and the sand storage chamber 5 in a substantially horizontal direction, the compressed air supply unit 6 is attached in the horizontal direction, and the sand supply pipe 12 is attached to the upper end side of the sand storage chamber 5. The vertical apparatus width can be further reduced. In one embodiment, the compressed air supply unit communicates with the sand blowing chamber 4 and supplies compressed air for blowing the core sand in the sand blowing chamber 4 into the core mold 1. 6, an aeration air supply unit 7 that is in communication with the sand blowing chamber 4 and that floats and fluidizes core sand in the sand blowing chamber 4 and supplies the sand blowing chamber 4, and a sand storage chamber 5 And a sand feed air supply unit 10 for supplying compressed air for feeding core sand in the sand storage chamber 5 to the sand blowing chamber 4 and three air supply units Since the core sand is blown and filled by combining the jets of compressed air from each air supply section, the filling property of the core sand should be improved even in an underblow type core molding machine. The effect of being able to There is.

  In one embodiment, the aeration air supply unit 7 is activated and the compressed air supply unit 6 is activated after a predetermined time. However, the present invention is not limited to this, and the aeration air supply unit 7 is activated. After that, when the pressure sensor 9 measures a predetermined pressure value in the blow head 2, the compressed air supply unit 6 may be operated. In this case, the predetermined pressure value in the blow head 2 may be a pressure value lower than the operating pressure of the compressed air supply unit 6. For example, it may be a pressure value within a range of 0.01 to 0.2 MPa.

  In one embodiment, the blow head 2 moves up and down with respect to the core mold 1 arranged at a predetermined position. However, the present invention is not limited to this, and the blow head 2 arranged at a predetermined position. The core mold 1 may be moved up and down.

  Furthermore, in one embodiment, as an example of the core molding machine, an example is shown in which a shell core molding machine that blows and fills resin-coated sand into a heated mold and molds a shell core is shown. However, the present invention can also be applied to core sand filling of a core molding machine by a cold box method which is a room temperature gas curing method.

  In one embodiment, the operating pressures of the aeration air supply unit 7, the compressed air supply unit 6, and the sand feed air supply unit 10 are not limited to specific pressure values. For example, the aeration air supply unit 7 has an operating pressure of 0.1 to 0.5 MPa, the compressed air supply unit 6 has an operating pressure of 0.1 to 0.5 MPa, and the sand feed air supply unit 10 has an operating pressure of 0.1 to 0.5 MPa. Also good.

  Furthermore, in one embodiment, the open / close gate 13 is opened and closed by a cylinder (not shown). However, the present invention is not limited to this, and the open / close gate 13 may be opened and closed by a cam mechanism.

  Furthermore, in one embodiment, the sand storage chamber 5 is bifurcated and divided into a left chamber 5a and a right chamber 5b. However, the present invention is not limited to this, and the sand storage chamber 5 is a single room (one room). ). In this case, for example, the compressed air supply unit 6 may be configured to penetrate the sand storage chamber 5.

  Next, an embodiment different from the above-described embodiment (hereinafter referred to as the first embodiment) will be described as a second embodiment. First, differences in configuration from the first embodiment will be described. In the second embodiment, as shown in FIGS. 6 and 7, the sand blowing nozzle 14 is placed at the lower end of the sand blowing hole 4b formed in the plate 4a attached to the upper end of the sand blowing chamber 4, and the lower end of the plate 4a. It is made to protrude from. The sand blowing hole 4b and the sand blowing nozzle 14 are in communication. This is the difference in configuration from the first embodiment. Other than this, the configuration is the same as that of the first embodiment. In addition, about the same component as 1st Embodiment, it shall show with the same code | symbol and shall abbreviate | omit the description. Since the operation of the second embodiment configured as described above is the same as that of the first embodiment, the description thereof will be omitted. However, in the second embodiment, the core sand in the sand blowing chamber 4 is the sand blowing nozzle 14 and the sand. It blows into the cavity 1a of the core mold 1 through the blow hole 4b. Only this point is different from the first embodiment.

  Next, the effect of the sand blowing nozzle 14 projecting from the lower end of the plate 4a at the lower end of the sand blowing hole 4b drilled in the plate 4a attached to the upper end of the sand blowing chamber 4 will be described in detail. explain. In the first and second embodiments of the present invention, as described above, after the core sand in the sand blowing chamber 4 is blown into the cavity 1a of the core mold 1, the aeration air supply unit 7, the compressed air supply unit 6 and the operation of the sand feed air supply unit 10 are stopped. Then, the core sand in the sand blowing chamber 4 sinks due to gravity drop, and an air layer (gap) K is formed between the upper surface of the core sand in the sand blowing chamber 4 and the lower end (lower surface) of the plate 4a ( (Refer FIG. 8, FIG. 9).

  FIG. 8 shows a state in which the air layer K is formed in the first embodiment (reference S is core sand). In the first embodiment, core sand is blown into the cavity 1a of the core core 1 for the next time in this state. However, at this time, since the core sand is blown into the cavity 1a together with the air in the air layer K, the core sand may not be sufficiently filled into the cavity 1a. Further, when the air layer K is formed, the core sand that has not been solidified in the cavity 1a may fall to the air layer K, which may cause a filling failure of the core sand into the cavity 1a. May cause.

  FIG. 9 shows a state in which the air layer K is formed in the second embodiment (reference S is core sand). In the second embodiment, core sand is blown into the cavity 1a of the core mold 1 next time in this state. At this time, since the tip of the sand blowing nozzle 14 is buried in the core sand, the air in the air layer K is not caught in the core sand, and the core sand is sufficiently filled into the cavity 1a. There are advantages. Even if the air layer K is formed, the tip of the sand blowing nozzle 14 is always buried in the core sand, so that core sand that has not been solidified in the cavity 1a is located at the air layer K. There is no falling. For this reason, there exists an advantage that the filling defect of the core sand in the cavity 1a can be prevented. The configuration in which the sand blowing nozzle 14 protrudes from the lower end of the plate 4a at the lower end of the sand blowing hole 4b drilled in the plate 4a attached to the upper end of the sand blowing chamber 4 has the above-described advantages. be able to.

  In the second embodiment, a female screw is formed on the inner surface of the sand blowing hole 4b, and a male screw is formed on the outer surface of the sand blowing nozzle 14, and these are screwed to form the sand blowing nozzle 14 in a plate. It protrudes from the lower end of 4a. However, the present invention is not limited to this, and a sand blowing nozzle 14 is disposed at the lower end of the sand blowing hole 4b, and the sand blowing nozzle 14 is fixed to the plate 4a by welding or the like. You may make it protrude from the lower end of the plate 4a.

  In the second embodiment, a cylindrical pipe is used as the sand blowing nozzle 14, but the shape of the sand blowing nozzle 14 is not limited to this, and may be, for example, elliptical.

  Furthermore, in 1st Embodiment and 2nd Embodiment, the plate 4a attached to the upper end of the sand blowing chamber 4 is comprised so that removal from the upper end of the sand blowing chamber 4 is possible. In addition, as a part which makes this plate 4a removable from the upper end of the sand blowing chamber 4, a fastening part, a clamp part, etc. are mentioned, for example.

  DESCRIPTION OF SYMBOLS 1 ... Core type | mold, 2 ... Blow head, 4 ... Sand blowing chamber, 4a ... Plate, 4b ... Sand blowing hole, 5 ... Sand storage chamber, 6 ... Compressed air supply part, 7 ... Aeration air supply part, 8 ... Exhaust Part, 9 ... pressure sensor, 10 ... sand feeding air supply part, 14 ... sand blowing nozzle.

Claims (6)

A core sand filling device in an underblow type core molding machine that blows core sand from below the core mold toward the upper core mold,
The core type;
A blow head disposed below the core mold so as to be movable up and down relative to the core mold, and divided into a sand blowing chamber and a sand storage chamber communicating with each other;
A compressed air supply section that communicates with the sand blowing chamber and supplies compressed air for blowing core sand into the core mold into the sand blowing chamber;
An aeration air supply unit that communicates with the sand blowing chamber and supplies aeration air that floats and fluidizes core sand in the sand blowing chamber to the sand blowing chamber;
An exhaust section communicating with the sand blowing chamber and exhausting compressed air remaining in the sand blowing chamber;
A sand feed air supply unit which communicates with the sand storage chamber and supplies compressed air for feeding core sand into the sand blowing chamber into the sand storage chamber;
A core sand filling device in a core molding machine.   The core sand filling apparatus in a core molding machine according to claim 1, wherein a pressure sensor for measuring the pressure in the blow head is attached to the sand blowing chamber.   3. The core according to claim 1, wherein a sand blowing nozzle is provided at a lower end of a sand blowing hole formed in a plate attached to an upper end of the sand blowing chamber so as to protrude from a lower end of the plate. Core sand filling device in molding machine. A core sand filling method in a core molding machine using the core sand filling device in the core molding machine according to claim 1,
A step of closely contacting the core mold and the sand blowing chamber;
Actuating the aeration air supply unit to float and fluidize core sand in the sand blowing chamber;
Actuating the compressed air supply unit and blowing core sand into the core mold in the sand blowing chamber;
Actuating the sand feeding air supply unit and feeding the core sand into the sand blowing chamber;
Stopping the operations of the aeration air supply unit and the compressed air supply unit;
Activating the exhaust unit and exhausting the compressed air remaining in the sand blowing chamber;
A step of stopping the operation of the sand feeding air supply unit;
A core sand filling method in a core molding machine having   The core sand filling method in the core molding machine according to claim 4, wherein operating pressures of the aeration air supply unit, the compressed air supply unit, and the sand feed air supply unit are the same pressure.   The core sand filling method in the core molding machine according to claim 4, wherein an operating pressure of the sand feeding air supply unit is higher than operating pressures of the aeration air supply unit and the compressed air supply unit.