JP2013163195A - Sand mold casting device with atmosphere open type gate riser, sand mold casting method using the same, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sand mold casting device with an atmosphere open type gate riser which reduces a cooling rate of a gate riser to prevent generation of a casting flaw, and to provide a sand mold casting method using the same and a method for manufacturing the same.SOLUTION: A sand mold casting device 10 with an atmosphere open type gate riser includes: a lower die 16 formed of foundry sand and including a cavity 18 corresponding to a cast product; an upper die 14 formed of foundry sand and including a gate riser 24 opened to the atmosphere and continued to the cavity 18; and a recess 26 provided around the gate riser 24 in the upper die 14 to secure an air layer around the gate riser 24.

Description

  The present invention relates to a sand mold casting apparatus with an open air feeder unit, a sand mold casting method using the apparatus, and a method for manufacturing the apparatus.

In sand mold casting, a cavity corresponding to a cast product is provided in the sand mold. The sand mold may be provided with a hot water portion for storing molten metal as a countermeasure for casting defects such as shrinkage. The molten metal stored in the feeder part is supplied to voids (nests) generated by solidification shrinkage as necessary, and the occurrence of casting defects is prevented.
For example, Patent Literature 1 discloses a non-atmospheric open-type hot water feeder, and in this hot-water feeder, a neck down shell is disposed in a recess provided in a sand mold. An air layer is formed between the neck down shell and the sand mold, and the cooling rate of the molten metal after pouring is delayed. Thereby, the hot water is supplied to the gap (nest) generated by the solidification shrinkage to improve the yield.

Sho-60-227946

  The feeder is provided for the purpose of replenishing the molten metal to the gap (nest) generated by the solidification shrinkage, and needs to be the final solidified part that solidifies after the molten metal at the site to be the product. However, when the hot water is small with respect to the part to be the product and the cooling rate of the molten metal at the part to be the product is relatively slow, the hot water may not be the final solidified part. In such a case, since the effect of the feeder cannot be obtained, there is a risk that casting defects such as shrinkage will occur.

As a countermeasure, it is possible to delay the cooling rate of the hot water by increasing the size of the hot water or keeping it warm.
However, when a heat generating agent or a heat insulating agent is used to delay the cooling rate of the feeder, there is a problem that the cost increases.
In addition, if the feeder is increased, the lifting weight and melting capacity of the crane must be increased, which causes problems such as the need to improve the factory equipment and the increase in material costs due to the increased amount of feeder. .

  On the other hand, in sand mold casting, in order to quickly take out a cast product, after the molten metal at a site to be a product is solidified, the hot metal is cooled by, for example, air cooling. However, since the feeder apparatus disclosed in Patent Document 1 is a non-atmospheric open type and cannot supply an air flow from the outside to the air layer around the neck down shell, the cooling speed of the feeder can be increased. Can not.

  Moreover, in the hot-water supply apparatus which patent document 1 discloses, the volume which can inject a molten metal is constant and a molten metal cannot be made to flow outside. That is, the non-atmospheric open-type hot water supply device cannot perform the “skein” operation for causing impurities in the molten metal to flow out.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an atmosphere-opening type hot water feeder portion that prevents the occurrence of casting defects by delaying the cooling rate of the hot water feeder with a simple configuration. An object of the present invention is to provide a sand mold casting apparatus, a sand mold casting method using the apparatus, and a method of manufacturing the apparatus.

In order to solve the above object, the present invention employs the following means.
The present invention includes a lower mold made of foundry sand provided with a cavity corresponding to a cast product, an upper mold made of foundry sand provided with a pressurizing portion open to the atmosphere connected to the cavity, and the presser in the upper mold. There is provided a sand casting apparatus with an atmosphere-opening type hot-water supply portion provided with a recess provided around the hot-water portion and securing an air layer around the hot-water supply portion.

  According to this sand mold casting apparatus with an open air type feeder unit, an air layer is secured around the feeder unit by the recess. Since the thermal conductivity of air is lower than the thermal conductivity of foundry sand, the air layer in the recess functions as a heat insulating layer. For this reason, even if it does not use a heat generating agent and a heat insulating agent, the cooling rate of a feeder can be delayed, and generation | occurrence | production of casting defects, such as a shrinkage nest, is prevented, suppressing the increase in manufacturing cost.

Moreover, according to this structure, the solidified substance of the molten metal of a feeder part can be rapidly cooled by sending air to a recessed part after the molten metal in a cavity solidifies. Therefore, the cast product can be taken out quickly, and the time required for casting can be shortened.
Furthermore, according to this structure, the impurities contained in the molten metal can be sent out to the concave portion by pouring the molten metal from the hot metal portion during pouring. In other words, the skein can be carried out by using the concave portion, whereby the quality of the obtained cast product can be further improved. In this case, the cooling rate of the feeder can be delayed by surrounding the feeder portion with the high-temperature molten metal that has flowed into the recess.

  Further, the present invention is a sand mold casting method using the sand mold casting apparatus with the open air type feeder unit, wherein molten metal is injected into the cavity, and the molten metal flows into the feeder unit through the cavity. Provided is a sand casting method comprising a hot water process.

  According to this sand mold casting method, an air layer is secured around the feeder part by the recess. Since the thermal conductivity of air is lower than the thermal conductivity of foundry sand, the air layer in the recess functions as a heat insulating layer. For this reason, even if it does not use a heat generating agent and a heat insulating agent, the cooling rate of a feeder can be delayed, and generation | occurrence | production of casting defects, such as a shrinkage nest, is prevented, suppressing the increase in manufacturing cost.

Preferably, in the pouring step, the molten metal is caused to overflow from the feeder part, and the overflowed molten metal is caused to flow into the recess.
According to this configuration, when the molten metal is poured, the impurities contained in the molten metal can be sent out to the concave portion by overflowing the molten metal from the molten metal portion. In other words, the skein can be carried out by using the concave portion, whereby the quality of the obtained cast product can be further improved.

Preferably, the sand mold casting method further includes a cooling step of cooling the molten metal in the feeder part after the pouring step, and in the cooling step, the upper part is configured so that an air flow flows into the recess. Blowing toward the mold is performed.
According to this structure, the molten metal in a feeder part can be rapidly cooled by sending air to a recessed part after the molten metal in a cavity solidifies. Therefore, the cast product can be taken out quickly, and the time required for casting can be shortened.

Preferably, the sand mold casting method further includes a lid arranging step of arranging a lid covering the concave portion after the pouring step.
According to this configuration, by disposing the lid, it is possible to prevent the escape of air in the recess, and to further enhance the heat insulation effect of the air layer.

  Further, the present invention is a method for manufacturing the sand mold casting apparatus with the above-described atmosphere-opening type feeder unit, an arrangement step of arranging a model of the feeder unit and a recess model in a casting frame, and after the arrangement step A mold filling step of filling the casting frame with foundry sand, and a removal step of removing the model of the feeder and the recess after the mold filling step, the recess model being flammable Provided is a method for manufacturing a sand mold casting apparatus with an open air type hot water feeder section, which is made of a material, and in the removing step, the model of the recess is burned and removed.

  According to this configuration, the concave model can be easily removed by burning and removing the concave model. As a result, according to this configuration, it is possible to easily manufacture the sand mold casting apparatus with an open air type feeder unit while suppressing an increase in manufacturing cost.

  According to the present invention, with a simple configuration, the occurrence of casting defects can be prevented by delaying the cooling rate of the feeder, and a sand casting method using the device, a sand casting method using the device, and A method of manufacturing the device is provided.

It is sectional drawing which shows schematically the structure of the sand type casting apparatus with an air | atmosphere open type feeder part of 1st Embodiment of this invention. It is a top view which shows roughly the structure of the sand type | mold casting apparatus of FIG. FIG. 2 is a perspective view schematically showing a cast product cast using the sand mold casting apparatus of FIG. 1. It is a figure which shows the process sequence of the sand mold casting method using the sand mold casting apparatus of FIG. It is a figure for demonstrating the lower mold production process in FIG. It is a figure for demonstrating the upper mold production process in FIG. It is a perspective view which shows roughly the model of the recessed part used in the upper mold production process of FIG. It is a figure for demonstrating the pouring process in FIG. It is a figure for demonstrating the cooling state of the molten metal in the slow cooling process in FIG. It is a figure for demonstrating the cooling process in FIG. It is a figure for demonstrating the cooling state of the solidified material of a molten metal just before execution of the hot metal solidification part cutting process in FIG. It is a figure for demonstrating the feeder solidification part cutting process in FIG. It is a figure for demonstrating the feeder solidification part cutting process in FIG. It is a figure for demonstrating the pouring process in the sand type | mold casting method of 2nd Embodiment. It is a figure for demonstrating the lid | cover arrangement | positioning process in the sand casting method of 3rd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention to that unless otherwise specified.

[Sand mold casting equipment and castings with open-air feeder section]
FIG. 1 is a cross-sectional view schematically illustrating a sand mold casting apparatus (hereinafter also simply referred to as a sand mold casting apparatus) 10 with an open air feeder unit according to an embodiment of the present invention, and FIG. FIG. FIG. 3 is a perspective view schematically showing a casting 12 cast using the sand mold casting apparatus 10.

  The sand mold casting apparatus 10 has an upper mold 14 and a lower mold 16. Each of the upper mold 14 and the lower mold 16 is a sand mold made of foundry sand. The foundry sand includes, for example, silica sand and clay, and may further include an inorganic or organic binder.

  A cavity (cavity) 18 is formed in the lower mold 16, and the shape of the cavity 18 corresponds to the shape of the casting 12 to be cast. Depending on the shape of the cast product, the cavity may be provided in the upper mold, and a core may be installed inside the cavity.

In the lower mold 16 and the upper mold 14, for example, ceramic pipes 20 and 22 constituting a runner are embedded. The lower end of the pipe 20 is opened at the bottom of the cavity 18, for example. On the other hand, the upper end of the pipe 22 opens at the upper surface of the upper mold 14 to form a gate.
Further, the upper die 14 is formed with a feeder 24 that is continuous with the upper portion of the cavity 18. The feeder 24 is, for example, a cylindrical space that penetrates the upper mold 14 in the vertical direction, and is open on the upper surface of the upper mold 14.

  Further, the upper mold 14 is formed with a cylindrical recess 26 surrounding the feeder 24. The recess 26 is opened on the upper surface of the upper mold 14. The recessed portion 26 is separated from the feeder 24 and is not in communication with the cavity 18. The distance from the outer edge of the feeder 24 to the inner edge of the recess 26 is preferably 30 mm or greater and 50 mm or less.

The inner peripheral surface (inner surface) and the outer peripheral surface (outer surface) of the recess 26 are separated from each other by a predetermined distance, and the recess 26 has a depth comparable to the depth of the feeder 24. . Therefore, the air in the recess 26 constitutes a cylindrical air layer that surrounds the feeder part 24. The distance between the lower surface of the recess 26 and the upper portion of the cavity 18 is preferably 30 mm or greater and 50 mm or less.
3 is obtained by solidification of the molten metal injected into the cavity 18, and does not include the solidified molten metal injected into the feeder part 24 (ie, the feeder solidified part).

[Sand casting method]
Hereinafter, a sand mold casting method using the sand mold casting apparatus 10 will be described.
FIG. 4 schematically shows a processing procedure of the sand mold casting method. The sand mold casting method includes a manufacturing method of the sand mold casting apparatus 10, and according to the sand mold casting method, the lower mold manufacturing step S10 is first executed.

  Here, FIG. 5 is a schematic view for explaining the lower mold manufacturing step S10. In the lower mold manufacturing step S10, first, as shown in FIG. 5A, the model 28 and the pipe 20 of the cavity 18 are arranged in a casting frame arranged on a surface plate. The model 28 is, for example, wooden. Then, as shown in FIG. 5 (b), the casting frame is filled with foundry sand and cured. Thereafter, as shown in FIG. 5C, the cast frame and the surface plate are turned upside down. Finally, as shown in FIG. 5D, after removing the surface plate, the model 28 is removed, and the lower mold 16 is completed.

Referring to FIG. 4 again, following the lower mold manufacturing process S10, an upper mold manufacturing process S20 is performed. However, the order of the upper mold manufacturing step S20 and the lower mold manufacturing process S10 is not particularly limited.
FIG. 6 is a schematic diagram for explaining the upper mold manufacturing step S20. In the upper mold manufacturing step S20, first, as shown in FIG. 6A, the model 30 of the feeder 24, the pipe 22, and the model 32 of the recess 26 are placed in the casting frame arranged on the surface plate. Arranged (arrangement step).

  Here, FIG. 7 is a perspective view schematically showing the outer shape of the model 32 of the recess 26. The model 32 has a cylindrical shape corresponding to the shape of the recess 26. The material of the model 32 is not particularly limited, but is preferably a combustible material that can be easily processed. Specifically, a polystyrene foam is preferable.

  Referring to FIG. 6 (b), after the placing step, the casting frame is filled with foundry sand and cured (molding step). After the molding step, as shown in FIG. 6C, the casting frame and the surface plate are turned upside down. Thereafter, after the surface plate is removed, a removal step of removing the model 30 of the feeder part 24 and the model 32 of the recessed part 26 is performed. In the present embodiment, first, as shown in FIG. 6D, the model 30 of the feeder 24 is removed. Then, as shown in FIG. 6E, the model 32 of the recess 26 is ignited and burned. As a result, the model 32 is removed as shown in FIG. 6F, and the upper mold 14 is completed.

  After the upper mold 14 and the lower mold 16 are completed, a mold matching process S30 for placing the upper mold 14 on the lower mold 16 is performed, and then a pouring process S40 is performed. In the pouring step S <b> 40, as shown in FIG. 8, the molten metal is injected into the pouring gate, whereby the molten metal is supplied to the cavity 18 and is also supplied to the feeder part 24 through the cavity 18.

  After the pouring step S40, a slow cooling step S50 is performed. In the slow cooling step S50, the upper mold 14 and the lower mold 16 are left to be cooled gradually until the molten metal inside the cavity 18 and the feeder 24 is solidified. In the slow cooling step S50, as shown in FIG. 9, even if the molten metal in the region A directly below the feeder 24 is in a semi-solid state, the molten metal in the feeder 24 is still in a molten state. After the molten metal has solidified, the molten metal in the feeder 24 is solidified.

  After all the molten metal has solidified, as a preferred embodiment, the cooling step S60 is performed. In the cooling step S60, as shown in FIG. 10, an air flow is sent toward the upper surface of the upper mold 14 using, for example, the fan 34. At this time, the direction of the air flow is adjusted so that the air flow flows into the recess 26.

By performing the cooling step S60, the solidified material of the molten metal in a high temperature state is cooled from above. In the region above the one-dot chain line B in FIG. 11, the temperature of the solidified material has decreased to some extent, that is, the temperature of the molten metal solidified portion where the molten metal injected into the molten metal portion 24 has solidified and its surroundings have decreased. Thereafter, a feeder solidified part cutting step S70 is performed.
In the hot water solidification part cutting step S70, as shown in FIG. 12, the casting sand is removed from the upper mold 14 together with the frame, and the hot metal solidification part is exposed. Then, as shown in FIG. 13, the feeder solidified part is cut off and removed.

  Thereafter, a removal step S80 is performed, and the molten metal injected into the cavity 18 is solidified, that is, the casting 12 is removed from the lower mold 16 together with the frame and the foundry sand is removed using, for example, a crane.

  According to the sand mold casting apparatus 10 and the sand mold casting method of the first embodiment described above, an air layer is secured around the feeder section 24 by the recess 26. The thermal conductivity of air (about 0.0241 W / (m · K)) is lower than the thermal conductivity of foundry sand (about 0.50 W / (m · K) in the case of chromite sand). The air layer functions as a heat insulating layer. For this reason, even if it does not use a heat generating agent or a heat insulating agent, the cooling rate of the feeder can be delayed, and the occurrence of casting defects such as shrinkage cavities in the casting 12 is prevented while suppressing an increase in manufacturing cost. .

  Moreover, in the sand mold casting method of the first embodiment, as a preferred aspect, in the cooling step S60, air blowing toward the upper mold 14 is performed so that an air flow flows into the recess 26. According to this configuration, by sending air to the recess 26 after the molten metal in the cavity 18 is solidified, the solidified material of the molten metal in the feeder 24 can be quickly cooled. Therefore, it is possible to quickly remove the solidified product of the molten metal in the feeder part 24 and take out the casting 12 quickly, thereby shortening the time required for casting.

  Furthermore, in the sand mold casting method of the first embodiment, as a preferred mode, the lifting weight of the crane that lifts the casting product 12 can be reduced by taking out the casting product 12 after separating the molten metal solidified portion, and the factory. There is no need to upgrade the equipment.

  Moreover, in the manufacturing method of the sand mold casting apparatus 10 of the first embodiment, the model 32 of the recess 26 can be easily removed by burning and removing the model 32 of the recess 26. As a result, according to this manufacturing method, the sand mold casting apparatus 10 can be easily manufactured while suppressing an increase in manufacturing cost.

[Second Embodiment]
Hereinafter, the sand mold casting method of the second embodiment will be described. Note that, in the configuration of the second embodiment, the same or similar configuration as the configuration of the first embodiment is denoted by the same reference numeral, and description thereof is omitted or simplified.

  The sand mold casting apparatus 10 is also used in the sand mold casting method of the second embodiment. As shown in FIG. 14, the sand mold casting method of the second embodiment is the first implementation only in that the molten metal overflows from the feeder 24 and the overflowed molten metal flows into the recess 26 in the pouring step S40. Different from the sand casting method of the form.

According to this configuration, the impurities contained in the molten metal can be sent out to the recess 26 by causing the molten metal to overflow from the hot metal portion 24 during pouring. That is, it is possible to perform skein using the concave portion 26, thereby further improving the quality of the cast product 12 to be obtained.
Further, by surrounding the feeder part 24 with the high-temperature molten metal that has flowed into the recess 26, the cooling rate of the feeder can be delayed.

[Third Embodiment]
Hereinafter, the sand mold casting method of the third embodiment will be described. Note that, in the configuration of the third embodiment, the same or similar configuration as the configuration of the first embodiment is denoted by the same reference numeral, and description thereof is omitted or simplified.

The sand mold casting apparatus 10 is also used in the sand mold casting method of the third embodiment. The sand mold casting method of the third embodiment is different from the sand mold casting method of the first embodiment only in that a lid arranging step is included between the pouring step S40 and the slow cooling step S50.
In the lid placement step, a lid 36 that covers the recess 26 is placed on the upper surface of the upper mold 14 as shown in FIG. The lid 36 is removed before the cooling step S60. In other words, the lid 36 is removed after all the molten metal has solidified. According to this configuration, by installing the lid 36, air escape in the recess 26 can be prevented, and the heat insulation effect of the air layer can be further enhanced.

The present invention is not limited to the first to third embodiments described above, and the first embodiment, the second embodiment, and the third embodiment are modified, or a combination of these embodiments. Including other forms.
For example, in the first embodiment described above, the solidified product is forcibly cooled in the cooling step S60 as a preferred mode, but may be gradually cooled by being left standing.

Further, in the first embodiment described above, as a preferred mode, the cast product 12 is taken out after cutting off the molten metal solidified. However, if the weight does not matter, the solidified solid of the molten metal is taken out and then the molten metal solidified. You may separate things.
Furthermore, the shape of the recess 26 is not limited to a cylindrical shape, and may be a rectangular tube shape. In this case, four plates may be used in combination as a concave model. Alternatively, the feeder part may be surrounded by a plurality of recesses. For example, two semicylindrical recesses may be formed in the upper mold 14.

DESCRIPTION OF SYMBOLS 10 Sand casting apparatus 12 with an open air type feeder part 12 Cast article 14 Upper mold 16 Lower mold 18 Cavity 24 Feeder part 26 Recess 32 Recess model

Claims (6)

A lower mold made of foundry sand provided with a cavity corresponding to the cast product,
An upper mold made of foundry sand provided with an open-air feeder section connected to the cavity;
A recess that is provided around the feeder in the upper mold and secures an air layer around the feeder;
A sand casting apparatus with an open air type hot water feeder. A sand mold casting method using the sand mold casting apparatus with an open air feeder unit according to claim 1,
A sand casting method, comprising: a pouring step of pouring molten metal into the cavity and flowing the molten metal into the feeder through the cavity. 3. The sand casting method according to claim 2, wherein in the pouring step, the molten metal is allowed to overflow from the hot metal portion, and the overflowed molten metal is caused to flow into the concave portion. After the pouring step, further comprising a cooling step of cooling the molten metal in the feeder part,
The sand casting method according to claim 2 or 3, wherein in the cooling step, air is blown toward the upper mold so that an air flow flows into the recess. The sand casting method according to any one of claims 2 to 4, further comprising a lid arranging step of arranging a lid that covers the concave portion after the pouring step. It is a manufacturing method of the sand type casting apparatus with an air release type feeder part according to claim 1,
An arrangement step of arranging a model of a feeder part and a model of a recess in a casting frame;
After the placing step, a molding step for filling the casting frame with foundry sand,
After the mold filling step, the removal step of removing the model of the feeder part and the model of the recess,
The concave model is made of a flammable material,
In the removing step, the model of the concave portion is burned and removed.

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