WO2017068951A1

WO2017068951A1 - Core-molding device and core-molding method

Info

Publication number: WO2017068951A1
Application number: PCT/JP2016/079318
Authority: WO
Inventors: 祐也福田; 大塚　真; 昇一西; 直洋三浦; 大剛岩永
Original assignee: マツダ株式会社
Priority date: 2015-10-20
Filing date: 2016-10-03
Publication date: 2017-04-27
Also published as: CN108136488A; CN108136488B; JP2017077572A; JP6380329B2; MX2018003448A

Abstract

A core-molding device (50) provided with a controller (100) configured so as to control actuation so that all intervals overlap, the intervals being an interval in which cast sand (41) is blown into a cavity (36) by the solenoid valve (11), an interval in which vibrations are applied by a vibrator (20) to the casting sand (41) thus blown into the cavity (36), and an interval in which the casting sand (41) thus blown into the cavity (36) is suctioned by a vacuum pump (24) so as to be drawn to the upper surface side of the cavity (36).

Description

Core molding apparatus and core molding method

The present invention relates to a core molding apparatus and a core molding method.

2. Description of the Related Art Conventionally, a core molding apparatus that molds a core by blowing casting sand into a cavity of a mold is known. In Patent Document 1, in a mold making apparatus for making a mold including a core, a blow head having a blow nozzle that houses cast sand and blows the foundry sand into a cavity at a lower portion, and when the foundry sand is blown A pressurized gas supply device for supplying the pressurized gas into the blow head, a sand temperature detecting device for detecting the temperature of the foundry sand in the blow head, and detecting the amount of the foundry sand in the blow head A sand amount detecting device, a solvent spraying device for spraying a solvent onto the foundry sand in the blow head, a temperature of the foundry sand in the blow head detected by the sand temperature detecting device, and a sand amount detecting device. A spray amount control device that controls the amount of solvent sprayed from the solvent spray device based on the detected amount of foundry sand is disclosed.

Japanese Patent No. 2008-149352

By the way, in recent years, in order to improve the cooling performance in the vicinity of the combustion chamber in the engine, there has been a request to increase the flow rate of cooling water and to secure a cooling area, and to ensure both the heat quantity of the heater and the maintenance of the exhaust temperature. Therefore, it is required to reduce the width of the water jacket and increase the surface area. In order to satisfy such a requirement, it is necessary to thin the core for forming the water jacket.

Generally, when the core is thinned, the cavity for molding the thinned core becomes narrower in the area where the foundry sand is filled, so that the foundry sand is less likely to be filled in the cavity. As a result, the filling density of the foundry sand in the cavity is lowered, and the strength of the molded core may not satisfy a desired strength. In particular, in a mold making apparatus that forms a mold by blowing and filling casting sand into a cavity, a pressurized gas is usually blown together with the foundry sand from a blowing nozzle. When the filling area | region of the foundry sand in the said cavity is narrow, the said pressurized gas will become difficult to escape from the said cavity. Thereby, the said pressurized gas remains between the foundry sands blown in the said cavity, and it is easy to form a clearance gap. As a result, the cavity is not sufficiently filled with foundry sand.

In the mold making apparatus described in Patent Document 1, based on the temperature of the foundry sand in the blow head detected by the sand temperature detecting device and the amount of foundry sand detected by the sand amount detecting device, By controlling the amount, before blowing the foundry sand kneaded with the pressure-sensitive adhesive into the mold, the pressure-sensitive adhesive is prevented from curing and the filling density of the foundry sand due to the curing of the pressure-sensitive adhesive is prevented. ing.

However, in the mold making apparatus described in Patent Document 1, there is no apparatus for filling the gap formed between the foundry sands, and there is a possibility that the strength of the core that is required to be thinned cannot be sufficiently satisfied.

The present invention has been made in view of such a point, and an object of the present invention is to improve the core strength, thereby realizing mass production of a thinned core and forming a molded core. It is to improve the dimensional accuracy of the child.

Device for solving the problem

In order to solve the above-mentioned problems, the present invention is directed to a core molding apparatus, a blow head that accommodates foundry sand, a blow nozzle that is disposed so as to communicate with the blow head, and an interior of the blow head. By supplying pressurized gas to the pressurized gas supply device for blowing and filling the foundry sand into the mold cavity through the blow nozzle, vibration is applied to the foundry sand blown into the cavity. The vibration device, the suction device that sucks the foundry sand blown into the cavity so as to be drawn toward the upper surface side of the cavity, and the operations of the pressurized gas supply device, the vibration device, and the suction device are as follows. A control device that can be controlled, wherein the control device includes a period of blowing the foundry sand by the pressurized gas supply device, and an upper portion of the foundry sand blown into the cavity. Each operation is performed so that there is a period in which the period during which vibration is applied by the vibration exciter and the period during which casting sand blown into the cavity is sucked by the suction unit overlap each other. I was supposed to.

According to this configuration, it is possible to increase the filling density of the foundry sand into the cavity and improve the strength of the core.

That is, when pressurized gas is supplied into the blow head by a pressurized gas supply device, and casting sand is blown into the cavity via the blow nozzle, the pressurized gas supplied together with the casting sand causes a gap between the casting sand in the cavity. There is a gap in In this state, when vibration is applied to the foundry sand in the cavity by the vibration device, the foundry sand rolls due to the vibration. At this time, the foundry sand rolls toward the gap portion, which is a low density portion, and the pressurized gas remaining in the gap is released from the gap. Thereby, the said clearance gap is filled and casting sand is filled to the bottom side of a cavity with dead weight. When the foundry sand is filled on the bottom side of the cavity, a void is formed on the upper surface side of the cavity. Further, foundry sand is blown into the gap from the blow nozzle. Thereby, the said clearance gap can be filled up with foundry sand.

Further, the foundry sand blown from the blow nozzle can be sucked by the suction device so as to be drawn toward the upper surface side of the cavity. Thereby, casting sand can be filled up to the upper part of a cavity which is a part which is hard to be filled with casting sand.

Therefore, the control device allows the molding gas to be blown by the pressurized gas supply device, the period for applying vibration to the casting sand blown into the cavity by the vibration device, and the casting sand blown into the cavity by the suction device. By performing each operation so that there is a period that overlaps with the suction period, the foundry sand blown into the cavity is rolled by the vibration device while blowing sand into the cavity from the blow nozzle. Then, the casting sand that has been filled into the bottom of the cavity and blown into the cavity can be drawn toward the upper surface of the cavity by a suction device to fill the upper surface of the cavity. Thus, the cavity can be filled with the foundry sand while filling the gap between the foundry sand, so that the filling density of the foundry sand in the cavity is increased and the strength of the core is improved. As a result, mass production of the thinned core can be realized.

Also, by filling the cavity with the foundry sand while filling the gap between the foundry sand, the density of the molded core becomes uniform. Thereby, deformation (expansion etc.) of the core when casting is performed using the molded core becomes uniform throughout the core. As a result, the dimensional variation in each part of the molded core is reduced, so that the dimensional accuracy of the core can be improved.

In the above core molding apparatus, the foundry sand is preferably foundry sand using an inorganic binder.

That is, by forming the core with casting sand using an inorganic binder, the strength of the core can be further improved as compared with the case of using an organic binder.

Another aspect of the present invention is an invention of a core molding method, which is arranged so as to communicate with the blow head by supplying a pressurized gas into the blow head containing the foundry sand. Blowing step of blowing and filling the foundry sand into the cavity of the mold through the blow nozzle provided, an exciting step of applying vibration to the foundry sand blown into the cavity, and into the cavity A suction step of sucking the blown foundry sand so as to draw it toward the upper surface of the cavity, a period during which the blow step is performed, a period during which the vibration step is performed, and the suction The period in which the process is executed has a period that overlaps with each other.

According to this configuration, the blowing process is executed, pressurized gas is supplied into the blow head, and foundry sand is blown into the cavity via the blow nozzle. At this time, a gap is formed between the foundry sands by the pressurized gas supplied together with the foundry sands. Vibration is applied to the foundry sand blown into the cavity in the vibration step. As a result, the foundry sand rolls due to vibration, fills the gap, and fills the bottom of the cavity with the foundry sand, creating a void on the upper surface side of the cavity. In the suction process, the foundry sand blown into the cavity is sucked so as to be drawn toward the upper surface side in the cavity.

Accordingly, the period in which the blowing process is performed, the period in which the vibration process is performed, and the period in which the suction process is performed have a period that overlaps each other, so that the casting sand is blown from the blow nozzle and the cavity is blown. The foundry sand blown into the cavity is rolled by vibration to fill the bottom side of the cavity, and the foundry sand blown into the cavity is sucked so as to be drawn toward the upper surface side of the cavity, and the upper surface side of the cavity Can be filled. Thus, the cavity can be filled with the foundry sand while filling the gap between the foundry sand, so that the filling density of the foundry sand in the cavity is increased and the strength of the core is improved. As a result, mass production of the thinned core can be realized.

Furthermore, by filling the cavity with the foundry sand while filling the gap between the foundry sand, the density of the molded core becomes uniform. Thereby, deformation (expansion etc.) of the core when casting is performed using the molded core becomes uniform throughout the core. As a result, the variation in the dimensions of the molded core is reduced, so that the dimensional accuracy of the core can be improved.

In the core molding method, after the first predetermined time has elapsed since the start of the blowing step, the vibration step is started, and after the second predetermined time has elapsed since the start of the vibration step, When the suction process is started and the suction process is completed, it is desirable that the blowing process and the vibration process are also completed.

That is, first, a blowing process is performed, pressurized gas is supplied into the blow head by a pressurized gas supply device, and foundry sand is blown into the cavity through the blow nozzle. Next, after a lapse of the first predetermined time from the start of the casting sand blowing, the vibration process is executed, and vibration is applied to the casting sand blown into the cavity. As a result, the foundry sand rolls due to vibrations, filling the gaps between the foundry sands, filling the foundry sand on the bottom side of the cavity, and creating voids on the upper surface side of the cavity. Then, after the elapse of the second predetermined time from the start of the vibration to the foundry sand, the suction process is executed so that the foundry sand blown into the cavity is drawn toward the upper surface side in the cavity. Sucked. Thereby, the foundry sand is filled up to the upper part of the cavity, which is a portion that is difficult to be filled with foundry sand.

In this way, by starting the blowing process, the vibration process, and the suction process in stages, the inside of the cavity is filled with the casting sand on the bottom side of the cavity and then the casting sand is filled on the upper surface side of the cavity. Can be gradually filled with foundry sand. Thereby, casting sand can be more efficiently filled into the bottom side and the upper surface side of the cavity.

After the first predetermined time has elapsed from the start of the blowing process, the vibration process is started, and after the second predetermined time has elapsed from the start of the vibration process, the suction process is started and the suction process is completed. In the core molding method when the blowing process and the vibration process are also finished, the blowing process is temporarily stopped from the start of the vibration process until the second predetermined time elapses. Then, it is desirable that the blowing process be resumed after the second predetermined time has elapsed.

According to this configuration, by temporarily suspending the blowing process until the second predetermined time has elapsed after the start of the vibration process, the foundry sand blown into the cavity is oscillated by the vibration at the bottom of the cavity. Since the foundry sand is not blown into the cavity while the side is filled, both the foundry sand and the pressurized gas are not supplied into the cavity. Thereby, the casting sand blown in the blowing step can be reliably filled in the bottom side of the cavity. Then, after the second predetermined time has elapsed from the start of the vibration process, the casting sand is blown again, and the suction of the blown casting sand is started to fill the upper surface side of the cavity with the casting sand. Can be made. Thereby, the casting sand can be more efficiently filled into the bottom side and the upper surface side of the cavity.

Also, since the casting sand is not blown into the cavity during the second predetermined time, the running cost can be saved.

In the core molding method, the foundry sand is desirably foundry sand using an inorganic binder.

As described above, the core strength can be further improved by using a molding sand made of an inorganic binder to form the core, rather than using an organic binder.

As described above, according to the core molding apparatus and the core molding method of the present invention, while casting sand is blown into the cavity, the casting sand blown into the cavity is vibrated and rolled, so that It is possible to fill the upper surface side of the cavity by filling the bottom side and further sucking the foundry sand blown into the cavity so as to be drawn toward the upper surface side of the cavity. Thus, the cavity can be filled with the foundry sand while filling the gap between the foundry sands, so that the filling density of the foundry sand in the cavity is increased and the core strength is improved. As a result, mass production of the thinned core can be realized.

Also, by filling the cavity with the foundry sand while filling the gap between the foundry sand, the density of the molded core becomes uniform. Thereby, the deformation of the core when casting using the molded core is made uniform throughout the core. As a result, the dimensional variation in each part of the molded core is reduced, so that the dimensional accuracy of the core can be improved.

It is a schematic block diagram which shows the core molding apparatus which concerns on embodiment of this invention. It is a mimetic diagram showing movement of foundry sand in a cavity when applying vibration to foundry sand in a cavity by a vibrator. It is a schematic diagram which shows the movement of the foundry sand in the cavity when the foundry sand in the cavity is sucked by the vacuum pump. It is a flowchart which shows the processing operation at the time of core molding by a controller. It is a graph which shows the change of the filling density of the foundry sand in a cavity at the time of performing a blowing process, a vibration process, and a suction process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a core molding apparatus 50 according to an embodiment of the present invention. The core molding apparatus 50 includes a blow head 1 having a sealed housing portion 2 that houses the foundry sand 41. The foundry sand 41 is foundry sand using an inorganic binder mainly composed of water glass (sodium silicate), and the sand surface is covered with the inorganic binder. In FIG. 1, a part of the upper end of the housing part 2 is opened, but in reality, the upper end of the housing part 2 is closed by a shutter 5 described later.

The foundry sand 41 is generated in the kneading unit 3 disposed on the upper side of the storage unit 2 and supplied to the storage unit 2. Specifically, sand such as silica sand and the above inorganic binder are put into the kneading unit 3, and these are uniformly kneaded by a kneader (not shown) provided in the kneading unit 3, so that the surface of the sand is an inorganic binder. As a result, the foundry sand 41 is generated. A shutter 5 that is opened and closed by a shutter drive mechanism 6 is disposed between the storage unit 2 and the kneading unit 3. When the shutter 5 is opened by the shutter drive mechanism 6, the foundry sand 41 is mixed with the kneading unit 3. It is dropped by its own weight and supplied to the housing part 2.

A blow plate 7 is attached to the lower end of the blow head 1, and a plurality of (three in FIG. 1) blow nozzles arranged so as to communicate with the inside of the accommodating portion 2. The upper end side of 8 is mounted. The lower end side of the blow nozzle 8 extends downward from the blow plate 7 and is then attached to an upper mold 35 a of the molding die 35 disposed below the blow plate 7 in the core molding apparatus 50. A cavity 36 is formed in the molding die 35, and the lower end side of the blow nozzle 8 attached to the upper die 35 a faces the cavity 36. That is, the blow head 1 and the cavity 36 are communicated with each other by the blow nozzle 8. The foundry sand 41 accommodated in the accommodating portion 2 of the blow head 1 is blown and filled into the cavity 36 via the blow nozzle 8, and has a core shape formed by the core molding apparatus 50. Examples of the core molded by the core molding apparatus 50 include a core for forming a water jacket of a cylinder head. The blow nozzle 8 may be a normally open type or an open / close type, and a part of the plurality of blow nozzles 8 may be a normally open type and the rest may be an open / close type.

On the other hand, an air supply port 2 a for supplying pressurized air (pressurized gas) into the accommodating portion 2 is provided at the upper portion of the side wall surface constituting the accommodating portion 2 of the blow head 1. The air supply port 2 a is connected to the air tank 12 via the electromagnetic valve 11. Factory air is stored in the air tank 12 at a constant pressure (about 0.2 MPa to 1 MPa) by a regulator (not shown). When the foundry sand 41 is blown into the cavity 36, the electromagnetic valve 11 is operated, and the pressurized air in the air tank 12 is supplied into the accommodating portion 2 of the blow head 1. Thereby, the foundry sand 41 in the accommodating portion 2 is blown and filled into the cavity 36 through the blow nozzle 8. From this, the solenoid valve 11 and the air tank 12 supply pressurized air into the blow head 1, thereby blowing and filling the foundry sand 41 into the cavity 36 of the mold 35 through the blow nozzle 8. Configure the supply device. The pressurized air supplied into the cavity 36 together with the foundry sand 41 goes out of the cavity 36 through the lower air vents 37 formed in the lower mold 35b of the molding die 35 (four in FIG. 1). It comes out.

The core molding apparatus 50 includes two vibrators 20 as vibration generators that apply vibration to the foundry sand 41 blown into the cavity 36 from the outside of the cavity 36. The two vibrators 20 are disposed so as to be in contact with the outer peripheral portion of the lower mold 35b and sandwich the lower mold 35b. The vibrator 20 applies vibration to the foundry sand 41 in the cavity 36 by transmitting vibration of a predetermined frequency into the cavity 36 through the lower mold 35b of the mold 35. At this time, vibrations in all directions including the horizontal direction, the vertical direction, and the oblique direction between the horizontal direction and the vertical direction are applied to the foundry sand 41 in the cavity 36. As will be described in detail later, the foundry sand 41 is filled into the bottom side of the cavity 36 by applying vibration to the foundry sand 41 blown into the cavity 36 by the vibrator 20. The vibrator 20 may be brought into contact with the upper die 35a instead of the lower die 35b. However, in order to fill the casting sand 41 to the bottom side of the cavity 36 by applying vibration, the bottom side of the cavity 36 is used. It is desirable to make it contact with the lower mold | type 35b which forms.

In order to prevent the vibration from the vibrator 20 from being transmitted to the entire core molding apparatus 50, an annular upper vibration isolator 52 is provided on the upper surface of the upper mold 35a, and on the lower surface of the lower mold 35b, An annular lower vibration isolator 53 is provided. Further, an upper plate 54 is provided on the upper side of the upper vibration isolator 52 in the core molding apparatus 50 so as to correspond to the shape of the upper vibration isolator 52, and the lower vibration isolator 52 in the core molding apparatus 50 is provided. A lower plate 55 is provided on the lower side so as to correspond to the shape of the lower vibration isolator 53. That is, the molding die 35 is disposed so as to be sandwiched between the upper and

lower plates

54 and 55 via the upper and lower

vibration isolating materials

52 and 53.

A ring-shaped seal member 56 is provided between the upper plate 54 and the blow plate 7 in the core molding apparatus 50. By arranging the sealing member 56, as shown in FIG. 1, a part of the lower surface of the blow plate 7, the inner surface of the sealing member 56, a part of the upper surface of the upper plate 54, the inner peripheral surface of the upper plate 54, and A suction space 21 is formed by the upper surface of the upper mold 35a.

The suction space 21 is a space for sucking the foundry sand 41 filled in the cavity 36 through the vacuum pump 24 described later. The suction space 21 communicates with the inside of the cavity 36 via an upper air vent 38 formed at the uppermost portion, which is the uppermost portion of the upper mold 35a.

From the suction space 21, the suction nozzle 22 extends through the seal member 56 to the outside of the suction space 21. One end side of the suction nozzle 22 is attached to the seal member 56 so as to face the suction space 21, while the other end side of the suction nozzle 22 is attached to the vacuum tank 23. A vacuum pump 24 is attached to the vacuum tank 23.

The vacuum pump 24 sucks the air in the suction space 21 into the vacuum tank 23 through the suction nozzle 22. As a result, the pressure in the suction space 21 decreases, so that the foundry sand 41 blown into the cavity 36 is drawn toward the upper surface side of the cavity 36 through the upper air vent 38. Therefore, the suction space 21, the suction nozzle 22, the vacuum tank 23, and the vacuum pump 24 constitute a suction device that sucks the foundry sand 41 blown into the cavity 36 so as to draw it toward the upper surface side of the cavity 36. Note that the suction strength by the vacuum pump 24 is strong enough to attract the foundry sand 41 located near the upper surface of the cavity 36 out of the foundry sand 41 blown into the cavity 36.

Further, the upper mold 35a and the lower mold 35b in the core molding apparatus 50 have a built-in heater 39 for increasing the temperature in the cavity 36. As will be described in detail later, when the inorganic binder is cured and the foundry sands 41 are bonded to each other, it is necessary to increase the temperature in the cavity 36 and perform high-temperature drying. At that time, the heater 39 is used.

Furthermore, in the housing part 2 of the blow head 1 in the core molding apparatus 50, a stirring member 25 for stirring the foundry sand 41 supplied into the housing part 2 is provided. The stirring member 25 loosens the foundry sand 41, extends in the vertical direction and is rotatably supported, and a substrate 25b fixed to the lower end of the rotary shaft 25a and extending in the horizontal direction. , And a plurality of (four in FIG. 1) stirring rods 25c provided on the substrate 25b. The upper end portion of the rotating shaft 25 a is connected to the stirring member driving mechanism 26. The agitating member drive mechanism 26 connects the drive motor 26a, the rotating shaft of the drive motor 26a and the rotating shaft 25a, a connecting member 26b made of, for example, a bendable wire, and the drive for driving the drive motor 26a. Circuit (not shown).

The core molding device 50 includes a controller 100 as a control device that controls the operation of the entire core molding device 50 including the operations of the solenoid valve 11, the vibrator 20, and the vacuum pump 24. The controller 100 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that is configured by, for example, RAM and ROM, and stores programs and data, and an electrical signal. And an input / output (I / O) bus for inputting and outputting.

Here, in particular, when forming a core that is required to be thin, such as a core for forming a water jacket of a cylinder head, the cavity 36 for forming the core is filled with foundry sand 41. Therefore, it becomes difficult for the foundry sand 41 to be filled in the cavity 36. As a result, the filling density of the foundry sand 41 in the cavity 36 decreases, and the strength of the molded core may not satisfy the desired strength. In particular, in the core molding apparatus 50 that molds the core by blowing and filling the molding sand 41 into the cavity 36 as in the present embodiment, the molding sand 41 is put into the cavity 36 by pressurized air as described above. In order to blow, pressurized air is blown together with the foundry sand 41 from the blow nozzle 8. At this time, since the cavity 36 has a narrow area where the foundry sand 41 is filled, the pressurized air is difficult to escape from the cavity 36. As a result, the pressurized air remains between the foundry sands 41 in the cavity 36, and a gap is easily formed. As a result, the cavity 36 is not sufficiently filled with the foundry sand 41.

Therefore, in the present embodiment, a period in which the foundry sand 41 is blown by the electromagnetic valve 11 and the air tank 12, a period in which vibration is applied to the foundry sand 41 blown into the cavity 36 by the vibrator 20, and a casting that is blown into the cavity 36. The filling density of the foundry sand 41 in the cavity 36 is improved so that there is a period in which the period of suction of the sand 41 by the vacuum pump 24 and the like overlaps all.

Specifically, the controller 100 starts the blowing process of blowing and filling the foundry sand 41 into the cavity 36, and then after the first predetermined time has elapsed, the controller 20 adds the vibrator 20 to the foundry sand 41 blown into the cavity 36. The vibration process for applying vibrations is started. When starting the vibration process, the controller 100 temporarily stops the blowing process. Then, after the second predetermined time has elapsed from the start of the vibration process, the controller 100 sucks the foundry sand 41 blown into the cavity 36 so as to draw it to the top of the cavity 36 by the vacuum pump 24 or the like. The suction process is started. When starting the suction process, the controller 100 restarts the blowing process and continues the vibration process. And when the said suction process is complete | finished, the said blowing process and the said vibration process are complete | finished. Thereby, while the suction process is being performed, the period in which the blowing process is performed, the period in which the vibration process is performed, and the period in which the suction process is performed all overlap. The first and second predetermined times are, for example, about 1 second.

Hereinafter, the movement of the foundry sand 41 in the cavity 36 in the vibration step and the movement of the foundry sand 41 in the cavity 36 in the suction step will be described in detail with reference to FIGS. 2 and 3.

FIG. 2 shows the movement of the foundry sand 41 in the cavity 36 when vibration is applied to the foundry sand 41 in the cavity 36 by the vibrator 20. When vibration is applied to the foundry sand 41 in the cavity 36 by the vibrator 20, the foundry sand 41 rolls in contact with the surface of the other foundry sand 41 due to the vibration. At this time, the foundry sand 41 rolls toward a low density portion, that is, a gap portion formed by the pressurized air, and the pressurized air remaining in the gap is released from the gap. As a result, the foundry sand 41 fills the gap and fills the bottom side of the cavity 36 by its own weight. In FIG. 2, only the left and right directions are indicated by arrows as examples of vibration directions, but in reality, vibrations in all directions including a direction perpendicular to the paper surface, a vertical direction, and an oblique direction therebetween are cast. Added to the sand 41.

Then, when the foundry sand 41 is filled on the bottom side of the cavity 36, a gap is generated on the upper surface side of the cavity 36. Casting sand 41 is blown and filled into the gap from the blow nozzle 8. Thereby, the gap formed between the foundry sands 41 is filled with the foundry sands 41.

FIG. 3 shows the movement of the foundry sand 41 in the cavity 36 when the foundry sand 41 in the cavity 36 is sucked by the vacuum pump 24 or the like. As described above, when the pressure in the suction space 21 is lowered by the vacuum pump 24, the foundry sand 41 in the cavity 36 is drawn toward the upper air vent 38 communicating with the suction space 21. Since the upper air vent 38 is provided at the top of the cavity 36, the foundry sand 41 blown into the cavity 36 is drawn toward the top of the cavity 36. As a result, the foundry sand 41 is filled up to the uppermost part of the cavity 36, which is a portion that is difficult to fill with the foundry sand 41.

In the vibration process and the suction process, the foundry sand 41 in the cavity 36 moves as described above. Therefore, the controller 100 performs a period during which the blowing process is performed, a period during which the vibration process is performed, and suction. The casting sand 41 blown into the cavity 36 is rolled by the vibrator 20 so as to fill the bottom side of the cavity 36 by controlling so that the period in which the process is executed and the period in which all the processes overlap is present. A gap is formed on the upper surface side of 36, and molding sand 41 is blown into the gap from the blow nozzle 8, and the foundry sand 41 blown into the gap is drawn toward the top of the cavity 36 by the vacuum pump 24 or the like. The upper surface side of the cavity 36 can be filled. Accordingly, the casting sand 41 can be filled into the cavity 36 while filling the gap formed between the foundry sands 41, so that the filling density of the foundry sand 41 in the cavity 36 can be improved.

In addition, after the first predetermined time has elapsed since the start of the blowing process, the vibration process is started, and after the second predetermined time has elapsed after the vibration process is started, the suction process is started. First, the foundry sand 41 is blown into the cavity 36, and the blown foundry sand 41 is filled into the bottom side of the cavity 36 by the vibration process, and then the upper surface side of the cavity 36 by the suction process. Can be filled with foundry sand 41. Thereby, the casting sand 41 is filled in the cavity 36 stepwise. As a result, the foundry sand 41 can be reliably filled in the bottom side and the top side of the cavity 36.

Further, the casting sand 41 in the cavity 36 is filled to the bottom side of the cavity 36 by stopping the blowing sand 41 from the start of the vibration process until the second predetermined time elapses. During this time, both the foundry sand 41 and the pressurized air are not supplied into the cavity 36, so that the foundry sand 41 blown in the first blowing process can be reliably filled into the bottom side of the cavity 36. Then, after the second predetermined time has elapsed from the start of the vibration process, the casting sand 41 is blown into the gap formed on the upper surface side of the cavity 36 by restarting the blowing of the foundry sand 41. be able to. In addition, after the second predetermined time has elapsed since the vibration process was started, the suction process is also started, so that the foundry sand 41 blown into the upper surface side of the cavity 36 is the uppermost part on the upper surface side of the cavity 36. Filled up to Thereby, the foundry sand 41 can be efficiently filled in the bottom side and the top side of the cavity 36. Further, since the supply of pressurized air is not executed during the second predetermined time, the running cost can be saved.

Next, a method for molding a core by the core molding apparatus 50 will be described with reference to a flowchart showing a processing operation at the time of core molding by the controller 100 shown in FIG. In the method described below, for example, a core for forming a water jacket of a cylinder head is formed.

First, in step S101, the controller 100 drives the kneader to knead sand such as silica sand supplied to the kneading unit 3 and an inorganic binder mainly composed of water glass. Thereby, the sand surface is covered with the inorganic binder, and the foundry sand 41 is generated.

In the next step S102, the controller 100 drives the shutter drive mechanism 6 to open the shutter 5 provided at the bottom of the kneading unit 3. Thereby, the foundry sand 41 is supplied from the kneading part 3 to the accommodating part 2 of the blow head 1. The foundry sand 41 supplied to the housing part 2 is loosened by the stirring member 25.

Subsequently, in step S103, the controller 100 sends a command to the electromagnetic valve 11, starts a blowing process, and blows and fills the casting sand 41 into the cavity. In the blowing process, the electromagnetic valve 11 is opened, and the pressurized air in the air tank 12 is supplied into the housing part 2. As a result, the foundry sand 41 in the accommodating portion 2 is blown and filled into the cavity 36 of the mold 35 via the blow nozzle 8.

Next, in step S104, the controller 100 determines whether or not a first predetermined time has elapsed since the start of the blowing process. As a result of the determination, if the first predetermined time has elapsed YES, the process proceeds to step S105, and if the first predetermined time has not elapsed, the process returns to step S103 to continue the blowing process.

In step S105, the controller 100 temporarily stops the blowing process and starts the vibration process to apply vibration to the foundry sand 41 blown into the cavity 36. That is, in this step S105, only the vibration process is executed. In the vibration process, the vibrator 20 is driven, and vibration is applied to the foundry sand 41 blown into the cavity 36 from the outside of the cavity 36. As a result, the foundry sand 41 in the cavity 36 fills the gap formed by the pressurized air supplied together with the foundry sand 41 and fills the bottom side of the cavity 36 by its own weight in the blowing step. When the foundry sand 41 is filled on the bottom side of the cavity 36, a void is formed on the upper surface side of the cavity 36.

In the next step S106, the controller 100 determines whether or not a second predetermined time has elapsed since the start of the vibration process. As a result of the determination, when the second predetermined time has elapsed, the process proceeds to step S107, and when the second predetermined time has not elapsed, the process returns to step S105 to stop the blowing process. The vibration process is continued.

In step S107, the controller 100 restarts the blowing process and starts the suction process in a state where the vibration process is continued. By restarting the blowing process, the foundry sand 41 is further blown into the gap formed on the upper surface side of the cavity 36 by the vibration process. In the suction process, the controller 100 drives the vacuum pump 24 to suck the air in the suction space 21 into the vacuum tank 23 through the suction nozzle 22, thereby casting sand 41 blown into the cavity 36. Are drawn toward the upper air vent 38 formed at the top of the cavity 36. Thereby, the foundry sand 41 is filled up to the uppermost part on the upper surface side of the cavity 36. Although not shown in the flowchart, the controller 100 ends the suction process and the blowing process and the vibration process after the third predetermined time has elapsed since the suction process was started. That is, while the suction process is being performed, the controller 100 is configured such that the period in which the blowing process is performed, the period in which the vibration process is performed, and the period in which the suction process is performed all overlap. Control. The third predetermined time is a time sufficient for the foundry sand 41 to be filled from the bottom side to the top side of the cavity 36.

In the next step S108, the temperature in the cavity 36 is raised by the heater 39 provided in the upper die 35a and the lower die 35b, and the foundry sand 41 is dried at a high temperature. As a result, excess water in the water glass evaporates, the water glass is cured, and the core is molded.

In the next step S109, the molding die 35 is removed and the core formed in step S108 is taken out. This completes the core molding.

FIG. 5 is a graph showing a change in the filling density of the foundry sand 41 in the cavity 36 when the blowing step, the vibration step, and the suction step are executed using the core molding device 50 according to the present embodiment. is there. In FIG. 5, the vertical axis represents the filling density of the foundry sand 41, and the horizontal axis represents the filling time of the foundry sand 41. The arrow shown on the lower side of the horizontal axis represents whether or not the blowing process, the vibration process, and the suction process are executed by the controller 100, and corresponds to the arrow in the portion where the arrow is described. This means that the process is being executed, and the part where the arrow is not described indicates that the process corresponding to the arrow has not been executed. Further, of the two broken lines shown in the graph of FIG. 5, the lower broken line represents the filling density when the casting sand 41 is filled into the cavity 36 only by the blowing process, and the upper broken line represents the blowing process. , The period during which the vibration process is performed, and the period during which the suction process is performed are all overlapped, and the filling density when the foundry sand 41 is filled in the cavity 36 is determined. To express.

Referring to FIG. 5, first, the blowing process is started, and the casting sand 41 is blown into the cavity 36, thereby increasing the filling density in the cavity 36. By this blowing step, the filling density rises to the filling density when the foundry sand 41 is filled into the cavity 36 only by the blowing step. The graph shows the change in the packing density on the bottom side of the cavity 36 and the change in the packing density on the upper surface side of the cavity 36. While only the blowing process is performed, the bottom of the cavity 36 is shown. Since the packing density rises at the same rate on both the side and the upper surface side, the two graphs appear to overlap.

As described above, after the first predetermined time (t1 in FIG. 5) has elapsed since the start of the blowing step, the blowing step is temporarily stopped and the vibration step is executed. When the vibration process is executed, the foundry sand 41 in the cavity 36 is filled on the bottom side of the cavity 36, so that the filling density on the bottom side of the cavity 36 increases as shown in FIG. On the other hand, since a gap is formed on the upper surface side of the cavity 36, the packing density on the upper surface side of the cavity 36 is lowered as shown in FIG.

Then, as described above, after the second predetermined time (t2 in FIG. 5) has elapsed after the start of the vibration process, the blowing process is resumed while the vibration process is being performed, and suction is performed. The process is started. Thus, the foundry sand 41 further blown into the cavity 36 is filled in the bottom side of the cavity 36, and the filling density on the bottom side of the cavity 36 is increased. After that, when the foundry sand 41 is filled in the entire bottom side of the cavity 36, there is no region filled with the foundry sand 41 on the bottom side of the cavity 36, so the filling density on the bottom side of the cavity 36 is saturated. On the other hand, the casting sand 41 is newly filled in the upper surface side of the cavity 36 by the blowing process and the suction process, so that the filling density on the upper surface side of the cavity 36 is increased. When a third predetermined time (t3 in FIG. 5) elapses after the suction process is started, the foundry sand 41 is filled up to the entire upper surface side of the cavity 36, and the filling density on the upper surface side of the cavity 36 is saturated. At this time, since the foundry sand 41 is filled up to the top of the cavity 36 by the suction process, the filling density on the bottom side and the filling density on the upper surface side of the cavity 36 are saturated to substantially the same value.

That is, as shown in FIG. 5, it can be seen that the filling density of the foundry sand 41 in the cavity 36 is increased by the core molding apparatus 50 according to the present embodiment. As described above, since the core density is improved by improving the packing density, mass production of cores that are required to be thinned, such as cores for forming the water jacket of the cylinder head, is realized. be able to. Further, by filling the foundry sand 41 until the filling density in the cavity 36 shows a saturation tendency, the density of the molded core becomes uniform, so that when the casting is performed using the molded core. The deformation of the core is uniform throughout the core. As a result, the variation in the dimensions of the molded core is reduced, so that the dimensional accuracy of the core can be improved.

Therefore, in the present embodiment, the blow head 1 that accommodates the foundry sand 41, the blow nozzle 8 disposed so as to communicate with the blow head 1, and the pressurized air is supplied into the blow head 1. The electromagnetic valve 11 and the air tank 12 for blowing and filling the foundry sand 41 into the cavity 36 of the mold 35 through the blow nozzle 8, the vibrator 20 for applying vibration to the foundry sand 41 blown into the cavity 36, and the cavity 36 A vacuum pump 24 for sucking the foundry sand 41 blown into the cavity 36 toward the upper surface side of the cavity 36, and a controller 100 capable of controlling the operations of the electromagnetic valve 11, the vibrator 20, the vacuum pump 24, and the like. The controller 100 includes a period in which the foundry sand 41 is blown by the electromagnetic valve 11 and the air tank 12, and the cavity 3. The period in which vibration is applied to the foundry sand 41 blown in by the vibrator 20 and the period in which the foundry sand 41 blown into the cavity 36 is sucked by the vacuum pump 24 and the like overlap each other. It is configured to perform an operation.

With this configuration, the foundry sand 41 blown into the cavity 36 from the blow nozzle 8 is rolled by the vibrator 20 to fill the foundry sand 41 on the bottom side of the cavity 36, and further, the foundry sand blown into the cavity 36. The sand 41 can be drawn to the top of the cavity 36 by the vacuum pump 24 or the like, and the foundry sand 41 can be filled on the upper surface side of the cavity 36. Accordingly, the casting sand 41 can be filled into the cavity 36 while filling the gap between the casting sands 41, so that the filling density of the casting sand 41 in the cavity 36 is increased, and the core strength is improved. As a result, mass production of the thinned core can be realized.

Also, the density of the molded core becomes uniform because the filling density of the foundry sand 41 into the cavity 36 is improved. Thereby, the deformation of the core when casting using the molded core is made uniform throughout the core. As a result, the variation in the dimensions of the molded core is reduced, so that the dimensional accuracy of the core can be improved.

The present invention is not limited to the above embodiment, and can be substituted without departing from the spirit of the claims.

For example, in the present embodiment, the foundry sand 41 is generated by kneading sand and an inorganic binder mainly composed of water glass. However, the present invention is not limited thereto, and the casting is obtained by kneading sand and an organic binder. Sand 41 may be generated. At this time, as the organic binder, for example, an organic binder mainly composed of a phenol resin and a polyisocyanate compound can be used.

Further, in the present embodiment, the blowing process is stopped until the second predetermined time elapses after the vibration process is started. However, the present invention is not limited to this, and the blowing process is also performed for the second predetermined time. The process may be continued.

The above-described embodiment is merely an example, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

The present invention is useful for a core molding apparatus and a core molding method for molding a core by blowing and filling casting sand into a cavity.

1 Blow Head 8 Blow Nozzle 11 Solenoid Valve (Pressurized Gas Supply Device)
12 Air tank (Pressurized gas supply device)
20 Vibrator (vibrator)
21 Suction space (suction device)
22 Suction nozzle (suction device)
23 Vacuum tank (suction device)
24 Vacuum pump (suction device)
35 Mold 36 Cavity 41 Foundry sand 50 Core molding device 100 Controller (control device)

Claims

A core molding device,
A blow head for receiving foundry sand;
A blow nozzle arranged to communicate with the blow head;
A pressurized gas supply device that blows and fills the foundry sand into the cavity of the mold through the blow nozzle by supplying pressurized gas into the blow head;
An excitation device for applying vibration to the foundry sand blown into the cavity;
A suction device for sucking the casting sand blown into the cavity so as to draw it toward the upper surface side of the cavity;
A control device for controlling the operation of the pressurized gas supply device, the vibration exciting device and the suction device,
The control device includes a period for blowing the foundry sand by the pressurized gas supply device, a period for applying vibration to the foundry sand blown into the cavity by the vibrating device, and a foundry sand blown into the cavity. The core molding apparatus is configured to execute each operation so that there is a period in which the period during which the suction apparatus sucks the air is overlapped.
The core molding apparatus according to claim 1,
The control device starts excitation of the foundry sand by the exciting device after the first predetermined time has elapsed since the start of blowing of the foundry sand by the pressurized gas supply device,
After the second predetermined time has elapsed since the start of the vibration to the foundry sand by the vibration device, the suction of the foundry sand by the suction device is started,
When the suction of the foundry sand by the suction device is terminated, the molding sand is blown by the pressurized gas supply device and the vibration to the foundry sand by the vibration device is also terminated. A core molding device.
In the core molding apparatus according to claim 2,
The controller temporarily blows the foundry sand by the pressurized gas supply device until the second predetermined time elapses after the exciting device starts exciting the foundry sand. The core molding apparatus is configured to resume the casting sand blowing by the pressurized gas supply device after the second predetermined time has elapsed.
The core molding apparatus according to any one of claims 1 to 3,
The core molding apparatus, wherein the foundry sand is foundry sand using an inorganic binder.
A core molding method,
By supplying pressurized gas into the blow head containing the foundry sand, the foundry sand is blown and filled into the mold cavity through the blow nozzle arranged to communicate with the blow head. A vibration process for applying vibration to the foundry sand blown into the cavity,
A suction step of sucking the foundry sand blown into the cavity so as to draw it toward the upper surface side of the cavity, and
A core molding method characterized by having a period in which a period in which the blowing step is executed, a period in which the vibration step is executed, and a period in which the suction step is executed all overlap.
In the core molding method according to claim 5,
After the first predetermined time has elapsed since the start of the blowing step, the vibration step is started,
After the second predetermined time has elapsed since the start of the vibration process, the suction process is started,
The core molding method, wherein when the suction step is finished, the blowing step and the vibration step are also finished.
The core molding method according to claim 6,
Until the second predetermined time has elapsed since the start of the vibration process, the blowing process is temporarily stopped, and after the second predetermined time has elapsed, the blowing process is resumed. Characteristic core molding method.
In the core molding method according to any one of claims 5 to 7,
The core molding method, wherein the foundry sand is foundry sand using an inorganic binder.