JPH10180414A - Method for molding core in mold and molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good mold core improving fluidity of sand in a cavity by blowing assist air from a nozzle inserted into the cavity toward difficult to filling direction while supplying and filling the sand into the cavity in a pattern for molding the mold. SOLUTION: The sand B is fed into the cavity 3 of the pattern 2 by opening a gate 13 at the lower part of a hopper 10 for supplying the sand. The gas in the cavity 3 is sucked to reduce the pressure by working a pressure reducing device. The sand B is dropped to just below a sand outlet 11 of the hopper and scattered to the circumference and the gas suction-reduced pressure is executed through sucking small holes 6 opened on the inner wall of the cavity 3 and shifted to the circumference. Only by the gas suction-reduced pressure, the sand B is not shifted to far position and a wall of the sand B is developed. Just before developing the wall of the sand B, the assist air is spouted from the pre-inserted blowing nozzle 17 and the sand B is blown off to the for position. At the time of completing the filling of the sand B, the reduced pressure operation is stopped and a box body 20 is descended and the blowing nozzle 19 is pulled out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for molding a mold core for efficiently molding a mold core used in casting.

[0002]

2. Description of the Related Art Conventionally, as a means for efficiently and effectively forming a casting mold, a molding cavity is filled with molding sand by reducing the pressure in a cavity of a casting mold to a high degree of vacuum.
A molding method based on so-called suction filling has been proposed. As means for forming a mold by suction filling, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-56441, the inside of a model cavity is connected to a reduced-pressure suction device to create a negative pressure. Supplies sand into the cavity opening from above, and blows compressed air inward from a nozzle located directly above the opening to promote the filling of the molding sand into the cavity. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 61-273242, there is a method in which gas is blown instantaneously from a blowing gas container at the same time when sand is supplied into a cavity of a model to obtain a filling effect. In addition, suction and filling are performed and vibration is applied to the model (see Japanese Utility Model Publication No. 2-14842).

[0003]

In the case of molding a mold core by the above-mentioned known suction filling, the kneaded sand flows from the hopper into the cavity of the model and diffuses and flows to the surroundings to fill the cavity. If the depressurized state in the cavity is increased in order to make the filling effective, the filling density naturally increases. In particular, if vibration is applied, the sand filling density inevitably increases, and the mold strength also increases.

[0004] When casting a cast steel product, hot break defects may occur in the final solidified portion of the product. It is presumed that the hot crack defect occurs because the mold strength is higher than the contraction stress generated in the casting due to the imbalance in the cooling rate. In other words, if a complex shape or a large core is molded by the vacuum molding method using the current suction filling, the sand filling density of the mold core and the mold strength will increase, causing the occurrence of hot break defects as described above. is there.

[0005] In addition to the problem caused by the increase in the density of sand filling, among the molding means using suction filling, a measure for increasing the filling effect by adding means for blowing air into the cavity of the model is described in the above-mentioned. JP-A-60-564
As disclosed in Japanese Patent Application Publication No. 41-41, in a system in which an air blowing pipe is arranged toward a supply port to a cavity of a sand supply hopper, a portion under a supply portion where supplied sand falls due to gravity automatically has a filling density. In addition to the fact that the direction of the blown air acts in the vertical direction in addition to the increase in the height of the cavity, for example, in the case of a cavity having a long shape in the lateral direction, the function of rapidly flowing sand even to the corner of the cavity cannot be exhibited. For this reason, a wall formed of stagnant sand is generated in the middle of the cavity, and a portion where filling is insufficient is generated. This result is difficult to confirm until the molding operation is finished and the molded core is removed from the model. For this reason, it is necessary to supplement by adding vibration from the outside or changing the conditions of air blowing, thereby increasing the sand filling density and increasing the mold strength.

Further, a method of applying suction and applying vibration during molding of a mold is effective for molding a complicated shape, but the filling density is inevitably increased and the strength of the mold is also increased. Therefore, it is difficult to obtain a favorable result when casting a long product with a cast steel product as described above.

In the present invention, in order to solve such a problem, an air blowing nozzle is inserted in a direction in which sand is difficult to fill in the cavity, and assist air is blown to increase the fluidity of the sand, thereby improving the molding effect. It is an object of the present invention to provide a molding method and a molding apparatus of a mold core capable of increasing the molding efficiency.

[0008]

Means for Solving the Problems and Action / Effect In order to achieve such an object, a method for molding a mold core according to a first aspect of the present invention is directed to a method for molding a mold for molding in a cavity of a mold to be negatively pressured by a pressure reducing device. Into the cavity from the sand supply port, and after the molding sand supplied from the sand supply port starts suction filling in the cavity, the assist air is blown from the blowing nozzle in a direction in which the sand is difficult to fill. It is characterized in that it is blown once or a plurality of times to assist the flow of sand and to be filled.

According to the present invention, by adding an operation of blowing assist air in a direction in which sand is difficult to fill in the cavity of the mold for molding, the desired mold core can be formed without excessively increasing the filling density. It became possible to mold. In addition, it is possible to mold at a low degree of decompression, and it is possible to reduce the sand filling density of the core, thereby improving the efficiency by reducing the degree of decompression required for molding, in other words, operating the pump of the decompression device Saving time,
The molding time is shortened, the capacity of the pump and the capacity of the receiver tank can be reduced, and the effect of increasing the economic effect such as reduction of the equipment cost can be achieved.

In the present invention, the assist air blowing nozzle having at least one blowing port provided in a horizontal direction is inserted from a supply port of molding sand into the cavity of the model, and the cavity is provided with a cavity. It is preferable that after the sand is supplied into the cavity, assist air is blown at a required time after the sand is supplied to the direction in which the ratio of the sand filling space length to the sand supply port diameter is large. This has the effect of preventing the flow of the sand supplied into the cavity from stagnating on the way and ensuring that the sand can be fed to the end.

Next, the molding device for a mold core according to the second invention can be installed in a molding machine and connected to a decompression device so as to be divided into at least two molds in which the inside of a molding cavity is made to have a negative pressure. Model, a sand supply hopper in which a discharge port is arranged above a supply port for supplying molding sand into a cavity of the model, an opening / closing gate provided in the discharge port of the hopper, and a model of the model. When the model is set by being supported by a spacer provided between the sand supply port and the sand supply port, an assist air blowing pipe inserted into the cavity from the sand supply port is provided. At least one assist air blowing nozzle is provided in the cavity in the direction in which sand is difficult to fill, and the other end of the assist air blowing pipe is It is characterized in that is connected via a Toea source and the control valve.

As described above, according to the second invention, the above-described effects can be reliably obtained by implementing the method according to the first embodiment of the present invention.

Further, in the present invention, it is preferable that the assist air blowing nozzle of the assist air blowing pipe is attached to a sand supply port of the cavity of the model so that the nozzle can freely enter and exit the cavity. By doing so, when the molding operation is completed, it is possible to perform treatment only by removing the assist air blowing nozzle from the model, and there is an advantage that the structure of the molding device can be simplified and the handling can be simplified.

Further, the molding device for a mold core according to the third aspect of the present invention can be installed in a molding machine and connected to a decompression device to divide the cavity for molding into a negative pressure at least into two parts. And a sand supply hopper in which a discharge port is disposed above a supply port for supplying molding sand into the cavity of the model, and a molding supply supplied to a central portion of the molding sand supply port. A dispersing head provided to disperse the sand, and an assist air blowing portion disposed immediately below the dispersing head, wherein the assist air blowing portion protrudes into the cavity from the lower portion of the model and is provided in the cavity of the model. The required number of assist air blowing holes is provided in the direction where sand filling is difficult, and the assist air blowing portion is connected to an assist air supply source via a control valve. It is characterized in.

In the present invention, since the decompression system and the assist air supply system are incorporated in the mold for mold molding, the model can be set on a molding machine for automatic attachment and detachment. This has an effect that the molding operation of the core can be automated.

In the present invention, the mold for molding preferably has a cavity inside a closed housing connected to a decompression device, and a partition wall for separating the cavity from the decompression chamber in the closed housing. A required number of exhaust holes are provided on the upper side,
It is preferable that the dispersion head of the molding sand and the assist air blowing unit are integrally protruded from the bottom of the closed casing into the cavity. In addition, the assist air blowing portion protruded from the bottom of the closed casing in the mold for molding to the inside of the cavity does not hinder the disassembly of the model after molding on at least one outer surface of the casing. Preferably, an assist air supply pipe is connected from the position. In addition, the model for the mold molding,
It is preferable that the closed casing and the cavity disposed therein can be divided and assembled into at least two upper and lower surfaces. By doing so, the automation of the molding operation of the mold core can be more effectively performed.

Further, in the present invention, the cavity in the mold for molding is connected to a pressure reducing device by a pipe connected to a small exhaust hole provided in a side wall of the mold, and a projecting portion protruding to an important part in the cavity is provided. It is preferable that the assist air blowing hole is provided in the airbag, and an assist air supply pipe is connected to the assist air blowing hole from outside. Alternatively, the cavity in the mold for molding is connected to a pressure reducing device by a pipe connected to a small exhaust hole provided in a side wall portion thereof, and the side portion of the assist air blowing portion protruding into the center portion of the cavity is provided at the side portion. Preferably, an assist air blowing hole is provided, and an assist air supply pipe is connected to the assist air blowing portion from outside. By doing so, there is an advantage that the decompression system for the cavity and the system for the assist air can be simplified and the combination of the accessory to the model can be facilitated.

Further, the supply port of the molding sand which is opened at the upper part of the cavity in the mold for molding is formed in an annular shape around the dispersion head, depending on the shape of the mold core to be molded. It is preferable to select and provide a plurality of them around the dispersion head. When the sand supply port is formed in an annular shape as in the former case, the sand can be dispersed and flowed substantially uniformly around the dispersion head. Also, if there are multiple sand supply ports like the latter,
The inflow direction into the cavity can be directed in a specific direction.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment of a molding method and a molding apparatus for a mold core according to the present invention will be described with reference to the drawings.

FIG. 1 shows a side view (a) and a plan view (b) of a mold core prepared as one embodiment according to the first invention. FIG. 2 is a schematic diagram showing an outline of a molding apparatus for a mold core according to the second invention in a cross-sectional view.

In these figures, the target template core A is
This is an example used when casting an axle housing, in which a large portion a for accommodating gears is formed in a central portion, and a long and thin portion b through which a shaft passes is formed on both sides. A baseboard c is formed on one side in the center.

An apparatus 1 for forming such a mold core A
Has a model 2 (a vertically divided mold having a well-known structure) forming the mold core A, and is provided with a large number of small suction holes 6 in a required distribution in a cavity 3 and is connected to a suction pipe 7. Known suction means connected to a decompression device (not shown) is provided. These are schematically shown in the drawings. A sand supply port 4 is disposed on the upper surface of the center of such a model 2, and the sand supply port 4 and a terminal portion in the longitudinal direction form a part of a baseboard.

A hopper 10 for supplying sand kneaded with a binder at a required mixing ratio is disposed above the model 2, and a sand outlet 11 of the hopper 10 and a sand supply port 4 of the model 2 are provided. The gate 13 is provided via a spacer 15 therebetween. In addition, at the part of the spacer 15, there is provided an assist air blowing pipe 16 having a blowing nozzle 17 at a tip end thereof, which is inserted into the molding cavity 3 of the model 2 at the time of assembling.

When installed in the cavity 3 of the model 2, the blowing nozzle 17 attached to the assist air blowing pipe 16 is disposed to the left and right in the longitudinal direction of the cavity 3. This assist air blowing pipe 16
Is supplied with a compressed air source (for example, a compressed air receiver tank 18) and a control valve 1 so that air at a required pressure is supplied.
9.

The molding sand B is used in the apparatus 1 for molding the mold core A, for example, by kneading a required amount of a resin and a curing agent. The procedure of the molding operation is as follows: the pressure of the assist air is adjusted, the molding sand B is put into the sand supply hopper 10, and the sand supply port 4 of the model 2 set in the molding machine (not shown) is set. After the preparation is made in accordance with the sand outlet 11 of the sand supply hopper 10, the gate 13 at the lower part of the hopper 10 is opened and the sand B is fed into the cavity 3 of the model 2.

Immediately after the supply of the sand B is started, the decompression device is operated to suction the interior of the cavity 3 of the model 2 under reduced pressure. Then, the sand B flowing into the cavity 3 from the sand supply port 4 first falls from the sand outlet 11 of the hopper 10 directly below the sand supply port 4 of the cavity 3 by gravity and is diffused around, and then the inner wall of the cavity 3 Flows to the surroundings due to the pressure difference from the outside due to the suction of the pressure reducing device through the small holes 6 opening to the outside. However, only by the suction negative pressure, the inflowing sand B does not flow sufficiently to a distant position in the cavity 3, and a region where the flow of the sand and the suction force by the decompression device are equilibrated eventually occurs. Walls will occur.

In view of the time when the wall of the sand B is generated, the blowing of the assist air is started a short time after the introduction of the sand. The operation time for blowing the assist air is arbitrarily changed depending on the shape and dimensions of the molded article (core). When the assist air blowing operation is performed for a preset time, the blowing is stopped. In addition,
During this time, the pressure reducing device operates in the cavity 3 to maintain the inside of the cavity 3 at a negative pressure.

By operating in this manner, the sand B supplied into the cavity 3 is supplied with the assist air from the blowing nozzle 17 inserted beforehand or immediately before the wall of the sand B is generated. Then, the sand B stagnated by the injection of the assist air is blown off toward the distant position, and the stagnated portion of the sand which has been in an equilibrium state flows at a stretch and fills the space in the cavity 3. Become. After the required time has elapsed and the negative pressure suction operation in the cavity 3 by the pressure reducing device is completed, the propulsive force of the sand B sent from the hopper 10 (atmospheric pressure acting on the sand stored in the hopper 10 × surface area + sand charged into the cavity) The sand B filled in the cavity 3 is compacted by the pressing force due to the difference between the mass × gravity) and the negative pressure maintained in the cavity 3.

When the sand is filled in the model 2, the vacuum suction operation is stopped, and the gate 13 of the sand supply hopper 10 is closed. Thereafter, the table 20 of the molding machine is lowered, and the assist air blowing pipe 16 and the blowing nozzle 17 incorporated in the spacer 15 attached to the hopper 10 are drawn out from the sand supply port 4 of the model 2 to the outside. The part of the molded core A from which the assist air blowing pipe 16 and the blowing nozzle 17 have been removed may be filled and repaired by hand before being taken out of the model 2. By performing the above operations, the molding is completed. Thereafter, the core A is taken out of the model 2 by a known means.

According to the present embodiment, by performing the molding of the core A as described above, the flow stagnation of the sand in the direction in which filling is difficult from the sand supply port in the model 2 is reduced by the assist air. Blow instantly by blowing and flow to a distant position,
By eliminating the decrease in the fluidity in the cavity 3 due to the decrease in the pressing force, the filling process can be performed quickly and effectively. The blown air is quickly sucked by the reduced pressure suction and does not remain in the cavity 3, and therefore does not hinder the filling molding by bubbles or the like after molding.

[0031]

Next, a specific example of the molding method according to the first invention will be described. The mold core to be molded is for axle housing casting as described above.

<Example> Sand to be used Sand used for general molding Binder As an alkali phenol self-hardening resin amount: 1.8 Wt% Curing agent: 25% / resin L / a (Length of the longest part L, diameter a of the sand supply port) of the model molding (see FIG. 3) = 1700/100 = 1
7 Inferring from past experimental examples, the greater the L / a, the greater the effect on the filling operation in the vacuum suction filling method. An assist air blow nozzle is inserted into the cavity of the model from the sand supply port, and two blow nozzles are attached to the left and right in the longitudinal direction of the cavity. Under such conditions, molding was performed by setting various conditions of the assist air and the reduced pressure suction. The results of the experiment are shown in Table 1 below.

[0033]

[Table 1]

As a result of this experiment, the following items (effects)
Was confirmed. 1) When molding a mold core, instability of sand filling was observed even at a reduced pressure of 5 Torr or less, but sand filling was stabilized by blowing assist air. 2) If assist air was blown in at a pressure of 5 kg / cm ^2, a good core could be formed even at a reduced pressure of 300 Torr. 3) If the molding is performed at a low degree of reduced pressure, the sand filling density of the core can be reduced. Note: Preparation: about 1,50 (g / cm ² ) → 5 Torr: 1.40 (g / cm ² ) → 300 Torr: 1.31 (g / cm ² ) (Assist air 5 kg / cm ² , blow for 3 seconds) From this, it is understood that the degree of pressure reduction in the cavity has a great effect on the sand filling density. 4) Improvement in efficiency due to reduction in the degree of decompression required for molding. That is, the pump operation time and the molding time are reduced. 5) The capacity of the pump and the capacity of the receiver tank can be reduced by reducing the degree of pressure reduction required for molding. As a result, equipment costs can be reduced.

As a comparative example, an experiment was conducted in which the assist air blowing direction was set to be directly downward as disclosed in the above-mentioned known technique (Japanese Patent Application Laid-Open No. 60-56441) with respect to the molding method of the present invention. (See FIG. 4) <Comparative Example> In this case, the conditions of the sand used, the binder, and the model are the same as those of the above-described embodiment. Assist air blowing method: Vertical direction in the cavity, Decompression degree: 100 Torr Assist air blowing condition: 3 seconds from 1 second after opening the gate at the bottom of the hopper, 1.5 kg / cm ² pressure

As a result, sand filling failure occurred. As shown in FIGS. 5 (a) and 5 (b), the state of sand filling in this case was such that air accumulation and a portion with low filling occurred. Naturally, such a molding cannot be used as a core.

An experiment was also conducted in which vibration (excitation force of 3 G) was applied to the model to blow the assist air as described above. As a result, although the sand filling property was improved, the sand was improved. The packing density of the sand increased, and it was unsuitable as a mold core for cast steel.

In the case of a cast iron mold core, it is advantageous to use both the above-described air assist and vibration of the model. In this case, the ON and OFF timings of the vibration are as follows: after the start of the reduced pressure suction and before the start of the blowing of the assist air, the vibration is turned ON, and after the blowing of the assist air is started and the vibration is turned OFF, the assist air is turned off. It is preferable to adopt a procedure of terminating the blowing of the air.

Next, another embodiment of a casting model (modeling apparatus) according to the third invention will be described with reference to the drawings.

In this embodiment, as shown in FIG. 6, a depressurizing system in a cavity is provided in a form in which a molding cavity is provided in a closed housing capable of dividing a model into at least two parts by partition walls. The path is a chamber type and the assist air path is a pipe type, or as shown in FIG. 7, the pressure reducing path in the cavity is a chamber type and the assist air path is a chamber type. The model can be divided into at least two parts, and as shown in FIG. 8, the decompression system in the molding cavity is a piping type,
The assist air system is also a pipe type, or FIG.
As shown in the above, the pressure reducing system in the cavity is a piping type, and the assist air system is a chamber type. It consists of

Therefore, first, a model 2A of the embodiment shown in FIG.
The housing 20 is provided with a cavity 21 which is partitioned by a partition wall 22 so that a target mold core can be formed therein, and is formed at the upper center of the housing 20 (not limited to this, for example, a mold core). (A core position may be provided), a sand supply port 23 is provided to communicate with the sand outlet 11a of the sand hopper 10A for molding, and the sand supply port 23 communicates with the upper part of the cavity 21. Thus, it is formed on the inclined peripheral surface of the downward recess. The housing 20 and the cavity 21 formed therein are configured to be vertically divided into two at the same level.

The housing 20 and the cavity 21 configured as described above are entirely separated by a partition wall 22 having a required thickness.
The space formed between the pressure chamber 24 and the cavity 21 is
Becomes The decompression chamber 24 is connected so that a communication hole 24a provided at the bottom of the housing 20 is connected to an opening 40 connected to a decompression device (not shown) provided on the molding machine side and the model 2A. It has been done.

A large number of small suction holes 25 are provided in the partition wall 22 on the upper side of the cavity 21 in a required distribution, and are formed so that the inside of the cavity 21 is made to have a negative pressure by suction by a decompression device during sanding work. . The upper and lower dividing surfaces of the partition wall 22 forming the cavity 21 are formed with a contact surface 22a having an appropriate width on the outside and provided with a flange so that a negative pressure can be generated in the cavity 21.

Further, in the center of the cavity 21 (not limited to this position), a cylindrical body 26 of an appropriate diameter which stands upright from the inner lower surface of the housing 20 so that a part thereof projects into the center of the sand supply port 23. Is protruding. This cylinder 26
Is integrally provided with a sand dispersion head 27 whose top surface is formed in an obtuse cone. Therefore, the sand supply port 2 to the cavity 21 is
3 is formed in a ring shape. The cylinder 26
, An assist air supply pipe 28 is connected from an appropriate position in the upper half (or lower half) of the housing 20. The assist air supply pipe 28 is connected to a compressed air source (for example, a compressed air receiver tank 18) via a control valve 19 so that air at a required pressure is supplied.
A cavity 2 is provided on the peripheral surface of the intermediate portion of the cylindrical body 26.
A plurality of assist air blowing holes 29 are formed in the direction in which the flowability of the sand B is poor.

The model 2A thus constructed is assembled, and the communication holes 24a which are connected to the above-described decompression chamber 24 in advance.
Is placed on a table of a molding machine having an opening 40 corresponding to the above, and the sand outlet 11a of the sand supply hopper 10A is prepared by matching with the sand supply port 23 on the upper surface of the housing 20. Thereafter, molding sand B (for example, as described in the above embodiment) adjusted to the required conditions is supplied into the cavity 21 from the sand supply hopper 10A.

Immediately after the supply of the sand B is started, the pressure reducing device is operated to suction the interior of the cavity 21 of the model 2A under reduced pressure. Then, the sand B flowing into the cavity 21 from the sand supply port 23 first falls from the sand outlet 11a of the hopper 10A to the sand supply port 23 of the cavity 21 by gravity, and is diffused around by the dispersion head 27 to be diffused around the cavity 21.
Flows into. Next, the partition 22 on the upper side of the cavity 21
Flows to the surroundings due to the pressure difference from the outside due to the suction of the pressure reducing device through the small suction holes 25 opening to the outside.
However, only by the suction negative pressure, the inflowing sand B does not sufficiently flow to a distant position in the cavity 21, and a region where the flow of the sand and the suction force of the decompression device are equilibrated eventually occurs, and the so-called sand B is generated. Walls will occur.

Therefore, in consideration of the time when the wall of the sand B occurs, the blowing of the assist air is started a little after the sand is injected. The operation time for blowing the assist air is arbitrarily set according to the shape and dimensions of the molded article (core). When the assist air blowing operation is performed for a preset time, the blowing is stopped. In addition,
During this time, the inside of the cavity 21 is maintained at a negative pressure by the operation of the pressure reducing device.

With the above operation, the sand B supplied into the cavity 21 is supplied with the assist air from the assist air blowing hole 29 of the cylindrical body 26 immediately before the wall of the sand B is generated or immediately before the wall is generated. The sand B which is injected and stagnated by the injection of the assist air is blown off toward a far position, and the stagnant portion of the sand which has been in an equilibrium state flows at a stretch and fills the space in the cavity 21 to be filled. become. After the required time elapses and the negative pressure suction operation in the cavity 21 by the pressure reducing device is completed, the propulsive force of the sand B sent from the sand supply hopper 10A (atmospheric pressure acting on the sand accumulated in the hopper 10A × surface area + cavity) The sand B filled in the cavity 21 is compacted by a pressing force due to a difference between the (mass of the sand to be input × gravity) and the negative pressure maintained in the cavity 3.

In this manner, the cavity 2 of the model 2A
When the sand B is filled in 1, the vacuum suction operation is stopped,
Next, the gate (not shown) of the sand supply hopper 10A is closed. Thereafter, the table 20 of the molding machine is lowered to separate it from the sand supply hopper 10A, and is moved from the sand supply hopper 10A position, or after the sand supply hopper 10A is moved, the model 2A is opened and the model 2A is opened. Take out the molded mold core. In addition, this model 2A
As described above, the partition wall 22 of the cavity 21 is separated vertically together with the housing 20 by separating the cylindrical body 26 for blowing assist air incorporated into the cavity 21 and the dispersion head 27 at an intermediate portion thereof. Then, the assembling / opening operation can be automated.

Next, the model 2B of the embodiment shown in FIG.
A housing 20 having a closed structure which is divided into upper and lower parts in the same manner as the above-described model 2A, and a cavity 21 which is partitioned by a partition wall 22 inside the housing 20 so that a desired mold core can be formed inside. A sand supply port 23 is provided at the upper center of the housing 20 and communicates with the upper part of the cavity 21. The supply path of the assist air is different from that of the model 2A. Therefore, the same portions as those of the above-described embodiment are denoted by the same reference numerals, and detailed description is omitted.

In this model 2B, the structure for creating a negative pressure in the cavity 21 is the same as that described above.
Regarding the path of the assist air, a sand dispersion head 2
The lower end of a cylindrical body 26A provided at the center of the cavity 21 and attached to the lower end of the cavity 21 is connected to an assist air supply pipe 28A on the lower surface of the housing 20, and a peripheral surface of an intermediate portion of the cylindrical body 26A. In addition, a plurality of assist air blow holes 29 are formed so as to face the direction in which the flowability of the sand B in the cavity 21 is poor.

In the case of the model 2B having such a configuration, when the molding sand B is supplied into the cavity 21 to perform the filling operation, the sand B is supplied from the sand supply port 23 depending on the shape of the target mold core. When the inflowing sand B causes a decrease in the flow, the assist air is intermittently blown in a plurality of times, so that the negative pressure in the cavity 21 and the sand supply port 23 are generated by suction and exhaust acting on the decompression chamber 24 side. In addition to the movement at the differential pressure from the side (atmospheric pressure) and the addition of the fluidity of the sand B by the assist air, the sand B smoothly flows without stagnation in the cavity 21, and a partial gap is formed. It can be filled without occurring. Of course, since the filling can be performed without giving a strong vibration, the sand B can be formed without excessively increasing the filling density. In addition,
The removal of the core from the model 2B after the molding of the mold core can be performed in the same manner as described above.

Next, the model 2C of the embodiment shown in FIG.
Is a molding die 30 that can be divided into upper and lower portions, for example, and a cavity 31 shaped to mold a desired mold core therein is connected to a sand outlet 11a of a sand supply hopper 10A at an upper central portion. A plurality of lower-concave-shaped sand supply ports 32 are provided at a required pitch, and sand B for molding is evenly fed into the cavity 31 from the sand supply ports 32. A plurality of small suction holes 33 are formed in the peripheral surface of the cavity 31 (preferably, the peripheral surface portion farthest from the sand supply port 32) (not limited to this). The small hole 33 is connected to a chamber 34 outside the mold 30, and this chamber 3
4 is connected to a suction pipe 35 connected to a pressure reducing device (not shown) so that the inside of the cavity 31 has a negative pressure during molding. The chamber 3 connected to each suction hole 33
Reference numeral 4 is arranged so as not to hinder the division of the mold 30.

As described above, the lower part of the molding die 30 is provided at the center of the cavity 31 (not necessarily at the center, for example, at the center of the mold core to be molded, such as the core of the mold core).
(A position suitable for dispersing the sand B in the inside), a protrusion 35 having a draft is provided on the outer peripheral surface thereof, and an assist air supply path 36 is formed in the protrusion 35 from the lower surface of the molding die 30. A plurality of assist air blowing holes 36a are formed from the inlet path 36 in a direction in which the flowability of the sand B in the cavity 31 is poor.

In the model 2C of this embodiment, when sand B is supplied from the sand supply hopper 10A to the sand supply port 32 of the molding die 30 via the sand outlet 11a during the molding operation, the plurality of sand supply ports 32 Sand B flows into cavity 31 and is dispersed. At this time, the flow of sand in the cavity 31 is promoted by the negative pressure of the suction from the suction holes 33 by the operation of the pressure reducing device, but the flow of the sand B is stagnated as described above. By injecting the assist air into the cavity 31 from the assist air supply passage 36, the stagnant sand B is blown off to promote the flow, so that the cavity 31 can be easily filled into the cavity 31. Of course, the blown assist air is discharged to the outside through the small suction holes 33, so that there is no stagnation to form a gap.

The removal of the mold core thus formed can be performed by the same operation as that described for the model 2A. In the model 2C of this embodiment, the small suction holes 33 are opened in the side wall portions of the cavity 31 and the like. It is preferable because the object can be achieved.

Further, the model 2 of the embodiment shown in FIG.
D is a molding die 30 that can be divided into two parts, for example, upper and lower, similar to the above-described model 2C, and has an upper central portion (not limited to this) with respect to a cavity 31A shaped to mold a desired mold core inside. Sand outlet 1 of sand supply hopper 10A
A plurality of lower-concave-shaped sand supply ports 32 communicating with 1a are provided at a required distribution in a plurality of places, and the sand supply ports 32 have a structure in which sand B for molding is almost uniformly fed into the cavity 31A. The structure for creating a negative pressure in the cavity 31A is the same as that of the model 2C. Therefore, the suction holes 33 which make them negative pressure
The description of the chamber 34 and the suction pipe 35 is omitted.

The cavity 31A of such a mold 30
Inside, the assist air blowing cylinder 38 from the lower part of the lower mold
Is provided at a required position (in this example, a central portion), and a plurality of assist air blowing holes 39 are formed in the peripheral surface of the blowing cylinder 38 in a direction in which the sand has low fluidity in the cavity 31A. Has been established. An assist air supply pipe is connected to the assist air blowing cylinder 38 from the outside so that the assist air can be supplied at a required time.

The basic operation of the model 2D thus configured is the same as that of the above-described embodiment, and the structure in which the assist air blowing structure can be increased in quantity in comparison with the model 2C. Has been. Therefore, the present invention is effective when employed in a molded article having a shape in which the fluidity of sand is not very good.

As described above, the molding apparatus for a mold core according to the present invention is suitable for, for example, a case in which the form according to the second aspect of the present invention involves a manual operation but is a long object. In the embodiment according to the third aspect of the present invention, the structure can be automated, so that it is effective to employ a molded article having a circular shape or a shape close thereto. Of course, even a long object is possible.

[Brief description of the drawings]

FIG. 1 is a side view (a) and a plan view (b) of a mold core prepared as one embodiment according to the first invention.

FIG. 2 is a schematic cross-sectional view showing an outline of a molding device for a mold core according to a second invention.

FIG. 3 is a view showing a relationship between a sand supply port of a cavity of a model and a length of a long-sized molding portion.

FIG. 4 is a schematic diagram showing a mode in which assist air is vertically blown into a cavity (conventional example).

5A and 5B are diagrams schematically showing a state of a mold core when molded by the apparatus shown in FIG. 4, in which FIG. 5A shows a side surface and FIG. 5B shows a plane surface.

FIG. 6 is a schematic cross-sectional view showing an outline of a molding apparatus for a mold core according to a third invention.

FIG. 7 is a schematic diagram showing an outline of a molding apparatus for a mold core according to another embodiment in a cross-sectional view.

FIG. 8 is a schematic diagram showing a cross-sectional view of an outline of a molding apparatus for a mold core according to another embodiment.

FIG. 9 is a schematic diagram showing an outline of a molding apparatus for a mold core according to another embodiment in a cross-sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Modeling apparatus 2, 2A, 2B, 2C, 2D model 3, 21, 31 Model cavity 4, 23, 32 Sand supply port into model 6, 25, 33 Suction small hole 7 Suction pipe 10, 10A Sand Supply hopper 11, 11a Sand outlet of hopper 13 Gate 15 Spacer 16 Assist air blowing pipe 17 Blowing nozzle 18 Receiver tank 19 Control valve 20 Housing 22 Partition wall 24 Decompression chamber 26 Cylinder body for assist air blowing 27 Dispersion head 28 Assist air supply pipes 29, 36a, 39 Assist air blowing holes 30 Molds 34 Chambers 35 Protrusions 36 Assist air supply paths 38 Assist air blowing cylinders A Mold core a Large volume b Long thin portions B Sand

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuya Kuriyama 31-1 Ueno, Hirakata-shi, Osaka Prefecture Komatsu Manufacturing Co., Ltd. Production Technology Laboratory Co., Ltd. (72) Kanji Katata 31-1 Ueno, Hirakata-shi, Osaka Co., Ltd. Komatsu Manufacturing Technology Laboratory

Claims (12)

[Claims] 1. A blowing nozzle for assist air is inserted from a sand supply port into a cavity of a mold for molding which is made to have a negative pressure by a pressure reducing device, and molding sand supplied from the sand supply port is inserted into the cavity. After suction filling is started, assist air is supplied from the blowing nozzle in a direction in which the sand is difficult to fill.
A molding method for a mold core, wherein the method is performed by injecting one or more times to assist the flow of sand and filling the sand. 2. A method for filling the cavity with sand, wherein at least one blow-out port is provided in the assist air blowing nozzle from a supply port of molding sand into the cavity of the model. 2. The method of claim 1, wherein after the sand is supplied into the cavity, assist air is blown at a predetermined time after the sand is supplied into the cavity in a direction in which the ratio of the space length to the diameter of the sand supply port is large. 3. 3. A mold for mold molding which can be installed in a molding machine and is divided into at least two molds in which the inside of the cavity for molding is made to have a negative pressure by connecting to a pressure reducing device, and a mold for molding in the cavity of the model. A sand supply hopper having a discharge port disposed above a supply port for supplying sand, and a spacer provided between an opening / closing gate provided at the discharge port of the hopper and the sand supply port of the model. When the model is set, an assist air blowing pipe inserted into the cavity from the sand supply port is provided, and a tip of the assist air blowing pipe is directed to a direction in which sand is difficult to fill in the cavity of the model. At least one assist air blowing nozzle is provided, and the other end of the assist air blowing pipe is connected to an assist air supply source via a control valve. And a molding device for a mold core. 4. The apparatus for molding a mold core according to claim 3, wherein the assist air blowing nozzle of the assist air blowing pipe is attached to a sand supply port of the cavity of the model so as to be able to enter and exit the cavity. 5. A mold for mold molding which can be divided into at least two molds which can be installed in a molding machine and connected to a decompression device to make the inside of the cavity for molding a negative pressure, and a mold for molding in the cavity of the model. A sand supply hopper in which a discharge port is arranged above a supply port for supplying sand, and a dispersion head provided to disperse molding sand supplied to a central portion of the molding sand supply port, An assist air blowing part disposed directly below the dispersion head, the assist air blowing part protruding into the cavity from the lower part of the model and required in a direction in which sand is difficult to fill in the cavity of the model. A number of assist air blowing holes are provided, and the assist air blowing portion is connected to an assist air supply source via a control valve. 6. The mold for molding is provided with a cavity inside a closed housing connected to a decompression device, and a required number is provided above a partition wall separating the cavity and a decompression chamber in the closed housing. 6. An exhaust hole according to claim 5, wherein the dispersion head of the molding sand and the assist air blowing portion are integrally provided to protrude from the bottom of the closed housing into the cavity. The molding device for a mold core according to item 1. 7. The assist air blowing portion protruding from the bottom of the closed casing in the mold for mold molding and protruding from the bottom of the closed casing to at least one outer surface of the casing to disassemble the model after molding. The molding device for a mold core according to claim 5 or 6, wherein the assist air supply pipe is connected from a position where no trouble occurs. 8. The mold for molding according to claim 5, wherein the closed casing and the cavity disposed therein can be divided and assembled into at least two upper and lower surfaces. The molding device for a mold core according to item 1. 9. A cavity in the mold for mold molding is connected to a pressure reducing device by a pipe connected to a small exhaust hole provided in a side wall portion thereof, and the assist air is provided at a protrusion projecting to a key portion in the cavity. The molding device for a mold core according to claim 5, wherein a blow hole is provided, and a supply pipe for assist air is connected from the outside to the assist air blow hole. 10. A side of an assist air blowing part which is connected to a pressure reducing device by a pipe connected to an exhaust hole provided in a side wall part of the mold in the mold for molding, and protrudes into a central part in the cavity. The molding device for a mold core according to claim 5, wherein the assist air blowing hole is provided in a portion, and an assist air supply pipe is connected to the assist air blowing portion from outside. 11. The molding sand supply port, which is opened at an upper part of a cavity in the mold for molding, is formed in an annular shape around the dispersion head. The molding device for a mold core according to item 1. 12. The molding sand according to claim 5, wherein a plurality of molding sand supply ports are formed around the dispersion head, the plurality of molding sand supply ports being opened at the top of the cavity in the mold for molding. An apparatus for forming a mold core according to the above.