JP2016117067A - Mold, and manufacturing method of mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold capable of reducing or preventing sticking of a mold material of a mold on a cast surface by preventing temperature rise, and maintaining the quality of the cast surface; and to provide a manufacturing method of the mold.SOLUTION: A mold 1 includes: a heat radiation material 10, which is a material having higher heat conductivity than a mold material and passable by gas generated from a molten metal, and which is arranged near a boundary surface with a cavity 4 into which the molten metal is poured; and a surface molding part 3A comprising the mold material, and arranged on the furthermore boundary surface side with the cavity 4 than the radiation material 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mold in which molten metal is injected to form a cast product and a mold manufacturing method.

  As a mold used for casting, a sand mold made by solidifying sand is known, and a high-temperature molten metal is poured into the sand mold. In the process where the metal poured into the sand mold is cooled and solidified, the sand mold is exposed to high heat from the hot metal. As a result, sand on the sand mold surface may be baked on the metal surface of the cast product. When sand is baked on the metal surface, it takes time and effort to remove the sand.

  In Patent Document 1 below, regarding a rapid cooling method applied when casting a thick cast product, a metal foam material is embedded as a chill material (cooling metal) in a sand mold before casting, and the cooling rate of the casting is set. An invention that suppresses the formation of voids while increasing is disclosed.

Japanese Patent Laid-Open No. 7-51826

  In order to prevent seizure, a slurry-like mold material containing particles having high fire resistance may be applied to the sand mold surface using a brush or the like. However, when casting a metal with a high melting point, such as high chromium steel, or in a sand mold that is difficult to dissipate heat (also called a “hot spot”), it becomes a high temperature condition, so seizure by the coating material Preventive measures may be insufficient.

  Note that the rapid cooling method related to the above-mentioned Patent Document 1 is a measure different from the seizure prevention. If the chill metal is applied to the cast product surface (casting surface), the chill metal melts into the product portion, or the chill metal surface is transferred to deteriorate the cast product surface, and the quality of the cast product is deteriorated. Therefore, the cooling metal cannot be applied to the surface of the product part of the cast product.

  The present invention has been made in view of such circumstances, and can suppress high temperature, reduce or prevent the mold material of the mold from being seized on the surface of the cast product, and the quality of the surface of the cast product. It is an object of the present invention to provide a mold capable of maintaining the above and a method for producing the mold.

In order to solve the above-mentioned problems, the mold and the method for producing the mold of the present invention employ the following means.
That is, the mold according to the present invention has a higher thermal conductivity than that of the mold material, and is a material through which a gas generated in the molten metal passes, and the heat dissipated in the vicinity of the boundary surface with the cavity into which the molten metal is poured. And a surface mold part that is made of the mold material and is disposed closer to the interface with the cavity than the heat dissipation part.

  According to this configuration, the molten metal is poured into the cavity, and when the metal is solidified, the casting is manufactured according to the shape of the cavity, and the heat radiating portion is not in the boundary surface with the cavity but in the vicinity of the boundary surface. Be placed. A surface mold part made of a mold material (for example, sand) is disposed closer to the interface with the cavity than the heat radiating part. Since the heat radiating portion is a material having a higher thermal conductivity than the mold material, the heat received from the molten metal can be efficiently released to the outside, and the seizure of sand on the cast product surface can be reduced or prevented. In addition, since the gas generated in the molten metal is a material through which the gas flows, the gas generated in the molten metal does not collect at the interface with the cavity. Furthermore, since the surface mold part made of the mold material, not the heat radiating part, is in contact with the molten metal, it is possible to reduce or prevent deterioration of the cast product surface due to the melting of the heat radiating part into the cast product and the transfer of the heat radiating part surface.

  In the above invention, the heat radiating portion is disposed corresponding to the boundary surface with the cavity.

  According to this configuration, the heat radiation portion arranged so as to correspond to the boundary surface with the cavity, for example, the shape of the mold surface or almost the entire area of the mold surface, receives the heat generated by the molten metal in the cavity. Therefore, heat can be efficiently released to the outside through the heat radiating portion.

  In the above invention, the heat radiating portion may extend to a portion facing the outside.

  According to this configuration, since the heat received from the molten metal in the cavity by the heat radiating portion is easily released to the outside through the heat radiating portion, the mold can be efficiently cooled.

  In the above invention, the heat dissipating part is installed at a position where the temperature of the surface on the cavity side when the molten metal is injected is lower than the melting point of the heat dissipating part.

  According to this configuration, when molten metal is injected into the cavity, the temperature of the heat transferred from the molten metal in the cavity to the heat radiating portion is lower than the melting point of the heat radiating portion. Can be prevented.

  In the above invention, the heat radiating portion may have a concave shape or a through hole.

  According to this structure, when the concave shape formed in the heat radiating part is formed, the adhesion between the mold material of the surface mold part and the heat radiating part is improved, and the surface mold part and the heat radiating part can be prevented from falling off. In addition, when a through hole is formed in the heat radiating part, the connectivity between the surface mold part and the mold material inside the heat radiating part is enhanced through the through hole. Can be prevented.

  In the mold manufacturing method according to the present invention, a heat dissipation part, which is a material having a higher thermal conductivity than the mold material and through which a gas generated in the molten metal passes, is disposed in the vicinity of the boundary surface with the cavity into which the molten metal is poured. And a step of disposing a surface mold part made of the mold material closer to the interface with the cavity than the heat radiating part.

  According to the present invention, it is possible to suppress the temperature rise, reduce or prevent the mold material of the mold from being seized on the surface of the casting, and maintain the quality of the surface of the casting.

It is a longitudinal cross-sectional view which shows the casting_mold | template which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the lower mold | type of the casting_mold | template which concerns on one Embodiment of this invention. It is the longitudinal cross-sectional view cut | disconnected by the III-III line | wire of FIG. It is a graph which shows the relationship between the pressure loss of a thermal radiation part, and a wind speed for every different porosity. 12 is a graph showing the relationship between temperature and time at a measurement point 1 of the core shown in FIG. It is a longitudinal cross-sectional view which shows the assembly process of the casting_mold | template which concerns on one Embodiment of this invention. It is the longitudinal cross-sectional view cut | disconnected by the VII-VII line of FIG. It is a longitudinal cross-sectional view which shows the 1st modification of the core of the casting_mold | template which concerns on one Embodiment of this invention. It is a bottom view which shows the 1st modification of the core of the casting_mold | template which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 2nd modification of the core of the casting_mold | template which concerns on one Embodiment of this invention. It is a cross-sectional view which shows the product part by which the temperature distribution at the time of using the conventional casting_mold | template was represented. It is a longitudinal cross-sectional view which shows the casting_mold | template which concerns on a comparative example.

Hereinafter, a mold according to an embodiment of the present invention will be described with reference to the drawings.
The mold 1 is a mold used for casting. In the present embodiment, the mold 1 is a sand mold in which the mold material is made of cast sand. The molten metal injected into the mold 1 is solidified to form a cast product. The mold 1 has a cross-sectional shape as shown in FIG. The mold 1 includes a lower mold 5 composed of an outer mold 2 and a core 3 and the like, and an upper mold 6 having a pouring system (not shown) and a hot water feeder section 7.

In the lower mold 5, a portion corresponding to the product portion of the cast product is formed. FIG. 2 is a longitudinal sectional view showing the lower mold 5 of the mold 1 shown in FIG. In the example using the casting_mold | template 1 shown in FIGS. 1-3, a product part has a hollow semicylindrical shape among the castings formed with the casting_mold | template 1, and a cross section is a semicircular arc shape. Examples of similar cast products include turbine casings.
In this case, the outer mold 2 of the lower mold 5 has an inner surface 2a that is recessed in a cylindrical shape. The core 3 of the lower mold 5 can be accommodated inside the outer mold 2 and has a cylindrical outer surface 3a. As shown in FIG. 3, projecting portions 3 </ b> B are formed at both ends of the core 3, and the projecting portions 3 </ b> B are placed on a stepped portion 2 </ b> A formed on the upper side of the outer mold 2.

  As shown in FIGS. 2 and 3, the core 3 is placed on the outer mold 2, whereby a cavity 4 is formed between the inner surface 2 a of the outer mold 2 and the outer surface 3 a of the core 3. The cavity 4 is a portion into which molten metal is injected, and is a portion corresponding to a product portion formed when the metal is solidified.

  The upper mold 6 is formed with a portion corresponding to the end face of the product portion, and also has a pouring system such as a gate and a runner and a feeder portion 7. The mold 1 has a configuration in which the lower surface of the upper mold 6 is matched with the upper surface of the lower mold 5, and the upper mold 6 is placed on the lower mold 5. In the mold 1, molten metal is injected into the cavity 4 through a pouring system.

Next, a detailed configuration of the core 3 will be described.
Unlike the outer mold 2, the core 3 does not face the external space, so that the heat of the molten metal is difficult to be released during casting. The core 3 includes a heat dissipation material 10 and a surface mold part 3A.

  The heat radiating material 10 is a material having a higher thermal conductivity than that of a mold material (for example, sand) and allowing gas generated by molten metal to pass therethrough. The heat dissipating material 10 is, for example, a foam metal made of open pores, specifically, an aluminum foam metal or the like. For example, when the core 3 has a semicylindrical shape, the heat dissipating material 10 has a semicylindrical shape with a semicircular cross section.

  The heat dissipating material 10 is arranged corresponding to the boundary surface with the cavity 4. For example, the heat dissipation material 10 is disposed so as to correspond to the boundary surface with the cavity 4, for example, the shape of the outer surface 3 a of the core 3 facing the cavity 4, or almost the entire area of the outer surface 3 a of the core 3. . Thereby, since the heat radiating material 10 receives heat generated by the molten metal in the cavity 4 in a wide area, the heat can be efficiently released to the outside through the heat radiating material 10.

  Since the heat dissipation material 10 has higher thermal conductivity than the mold material, the heat received from the molten metal in the cavity 4 can be efficiently released to the outside. When the mold material is, for example, cast sand, the thermal conductivity is about 1 W / (m · k), and the heat dissipation material 10 has a thermal conductivity exceeding this value. And since the higher cooling effect is acquired, so that the heat dissipation material 10 has the larger difference in thermal conductivity with a casting_mold | template material, it is desirable to have a value with high thermal conductivity.

  Further, when the heat radiating material 10 is a foam metal, the weight is reduced as compared with a dense metal material. Therefore, when the core 3 is installed on the outer mold 2, it is difficult to fall off due to its own weight. Furthermore, since the heat radiating material 10 is a material through which gas can pass, the gas generated from the molten metal does not accumulate on the boundary surface between the cavity 4 and the core 3, that is, the outer surface 3 a of the core 3.

  The lower limit of the porosity of the heat dissipation material 10 is 75%, and the upper limit is a value capable of maintaining the shape as a foam. Note that the heat dissipation material 10 becomes denser as the porosity is lower. FIG. 4 is a graph showing the relationship between the pressure loss of the heat dissipating material 10 and the wind speed when the heat dissipating material 10 is a foam metal for each of different porosity, and is data obtained from experiments. In this experiment, when the porosity was 70%, the gas did not pass through the heat dissipation material 10. Therefore, it is difficult to apply a foam metal having a porosity of 70% or less.

  The foam metal of the heat dissipating material 10 preferably has continuous pores in the plate thickness direction. If there is a portion where the pores are continuous, the gas generated on the cavity 4 side is removed from the core 3. It can be released to the center side. As a result, the generated gas is discharged to the outside through the center side portion of the core 3.

  According to the graph of FIG. 4, it can be seen that the pressure loss increases as the wind speed increases regardless of the porosity of the heat dissipation material 10. It can also be seen that, at the same wind speed, the pressure loss increases as the porosity decreases, and the rate of increase in pressure loss increases as the porosity decreases.

  As shown in FIG. 1, a heat dissipation material 11 made of the same material as the heat dissipation material 10 is also provided in the upper mold 6. The heat dissipating material 11 in the upper mold 6 extends to a portion facing the outside. The heat dissipating material 11 is disposed in contact with the heat dissipating material 10 in the core 3. Thereby, the heat which the heat radiating material 10 has can be transmitted to the heat radiating material 11, and the heat received from the molten metal can be efficiently released to the outside. Further, the gas generated in the cavity 4 can be efficiently guided to the outside.

  The surface mold portion 3 </ b> A is made of a mold material (cast sand in the case of a sand mold), and is installed on the surface of the heat dissipation material 10. That is, the surface mold portion 3 </ b> A is disposed on the boundary surface side with the cavity 4 rather than the heat radiating material 10. The surface mold part 3A is provided with substantially the same thickness, and is installed so as to cover the entire heat dissipation material 10.

  Thereby, at the time of casting, 3 A of surface mold parts which consist of mold materials contact with a molten metal, and the thermal radiation material 10 does not contact with a molten metal. Therefore, it is possible to reduce or prevent the heat radiating material 10 from being melted into the cast product or the surface shape of the heat radiating material 10 being transferred to deteriorate the cast product surface.

  The thickness of the surface mold portion 3A is such that the temperature of heat transferred from the molten metal in the cavity 4 is lower than the melting point of the heat dissipation material 10 on the surface of the heat dissipation material 10 on the cavity 4 side. That's fine. Therefore, when the heat dissipating material 10 is an aluminum foam, the temperature of the heat transferred from the molten metal in the cavity 4 to the heat dissipating material 10 is increased when the surface mold portion 3A is provided with a thickness of about 50 mm. Since it is lower than the melting point of the body, melting of the heat dissipation material 10 can be prevented.

  If the thickness of the surface mold portion 3A is too thin, the surface mold portion 3A may not only be higher than the melting point of the heat dissipation material 10, but also the strength of the surface mold portion 3A may be reduced, resulting in a surface made of cast sand. There is a possibility that the mold part 3A falls off before casting and sand biting (a state in which sand is interposed in the cast product) may occur. On the other hand, if the thickness of the surface mold portion 3A is too thick, it becomes difficult to release the heat received from the molten metal by the heat radiating material 10 to the outside, so that a sufficient cooling effect cannot be obtained.

  As described above, according to the present embodiment, by installing the heat dissipating material 10 having a higher thermal conductivity than the mold material used for the mold 1 in the core 3, the conventional casting without the heat dissipating material 10 being installed. In comparison, the heat of the metal in the cavity 4 can be quickly released to the outside. As a result, the temperature decrease of the portion (hot spot) where heat has been easily trapped in the cavity 4 is promoted, and seizure of sand to the cast product can be reduced or prevented.

  Moreover, in the method using the conventional cooling metal, the cooling metal is exposed to the cavity side. On the other hand, in the present embodiment, the surface mold portion 3 </ b> A made of cast sand is installed on the boundary surface side with the cavity 4 rather than the heat radiating material 10. Therefore, it is possible to reduce or prevent the heat dissipation material 10 from being melted into the cast product and deterioration of the cast product surface due to the transfer of the surface shape of the heat dissipation material 10.

  Furthermore, since the heat radiating material 10 is a material through which gas flows, the gas generated when the molten metal solidifies does not collect below the heat radiating material 10 and passes inside the core 3. Go. As a result, it is possible to prevent the occurrence of gas defects such as a fluttered surface of the cast product.

Next, the manufacturing method of the casting_mold | template 1 which concerns on this embodiment is demonstrated.
First, the casting sand for the outer mold 2 is filled with casting sand while placing a model corresponding to the outer surface of the finished product. And the outer mold | type 2 by which the recessed part was formed inside is formed by removing a model from a casting frame.

  Moreover, the semi-cylindrical core 3 is formed by filling the model in which the recesses for the core 3 are formed with filling sand and removing the core 3 from the model. In the formation of the core 3, first, the cast sand that becomes the surface mold portion 3 </ b> A portion is arranged with a thickness of about 50 mm, and then the heat radiating material 10 is placed on the portion that becomes the surface mold portion 3 </ b> A. Then, the core 3 is completed by further filling the inside of the heat dissipation material 10 with casting sand. The order in which the core 3 is formed is not limited to this procedure.

  Further, the casting mold for the upper mold 6 is filled with casting sand while placing a model corresponding to a pouring system such as a gate and a runner and the feeder 7. And the upper mold | type 6 in which the pouring system and the feeder part 7 were formed is formed by removing a model from a casting frame. As shown in FIG. 1, the heat radiation material 11 is arranged on the upper mold 6 so that the heat radiation material 11 of the upper mold 6 is connected to the extension of the heat radiation material 10 of the core 3.

  After the outer mold 2 and the core 3 are formed, the core 3 is disposed inside the outer mold 2. As shown in FIGS. 6 and 7, the core 3 is arranged by lifting the core 3 and inserting it into the center portion of the outer mold 2. The core 3 is lifted, for example, by hooking a hook 20 of a lifting machine such as a chain block on a wire 21 attached in advance to the core 3 when the core 3 is formed, and is arranged at a predetermined position.

  And the protrusion 3B formed in the both ends of the core 3 is mounted on the upper side of the outer mold | type 2, and the lower mold | type 5 of the casting_mold | template 1 is completed. At this time, a cavity 4 corresponding to a product portion is formed between the outer mold 2 and the core 3.

  After the upper mold 6 is formed, the upper mold 6 is lifted using the lifting machine in the same manner as the core 3, and the upper mold 6 is placed on the outer mold 2 and the core 3. Thereby, the mold 1 as shown in FIG. 1 is completed.

Next, a casting method using the mold 1 according to this embodiment will be described.
Molten metal is injected into the cavity 4 and the feeder 7 through the pouring system of the mold 1. Then, the injected metal is solidified to form a cast product, and the formed cast product is taken out from the mold 1.

  In the case of the conventional example in which the heat radiating material 10 is not installed, as shown in FIG. 11, in the casting process, the cavity 4 has a portion that is difficult to radiate to the outside, and a region (hot spot) where heat is likely to be accumulated is generated. . In FIG. 11, it is shown that the darker color part is hotter than the lighter part. In the case of the conventional example, at the measurement point 1 of the core 3 shown in FIG. 11, the temperature tends to decrease after excessively rising, as indicated by the plotted circles in FIG. The measurement point 1 of the core 3 is a point close to the hot spot. In such a case, since the casting sand of the core 3 is exposed to a high temperature, the casting sand on the surface of the core 3 is baked on the cast product.

  On the other hand, in the present embodiment in which the heat dissipating material 10 is installed, at the measurement point 1 of the core 3, as shown by the plot square mark in FIG. Calm down. This is because the heat of the metal in the cavity 4 is released to the outside without heat being accumulated in the portion corresponding to the hot spot generated in the conventional example. Thereby, since the temperature of the core 3 is not exposed to an abnormally high temperature, it is possible to reduce or prevent the casting sand on the surface of the core 3 from being seized on the cast product.

  As a comparative example, FIG. 12 shows a case where a dense metal material 40 that does not allow gas to pass through is provided in the core 33 in a portion corresponding to the heat dissipation material 10 of the present embodiment. In the case of the comparative example shown in FIG. 12, the gas 32 generated from the molten metal 30 injected into the cavity 34 cannot pass through the metal material 40, and the surface mold part 33 </ b> A side, that is, the outer surface 33 a of the core 33 and the molten metal. It accumulates on the interface with 30. This causes gas defects on the surface of the casting.

  On the other hand, in the case of the present embodiment using the heat dissipation material 10 that is a material through which gas can pass, the gas generated from the molten metal injected into the cavity 4 passes through the heat dissipation material 10. As a result, the casting can be formed by solidifying the metal without causing gas defects on the surface of the casting.

In addition, although embodiment mentioned above demonstrated the case where the surface by the side of the cavity 4 in the thermal radiation material 10 was a semi-cylindrical shape without an unevenness | corrugation, this invention is not limited to this example.
For example, as shown in FIG. 8, the heat dissipating material 12 has an uneven shape in the longitudinal section. For example, when the heat dissipating material 12 is installed in the core 3, the concave portion 13 is provided at a lowermost position and has a cross-sectional shape that is recessed upward, and has a shape in plan view as shown in FIG. 9. It is circular. In this case, the recesses 13 are formed at a plurality of locations with appropriate intervals in the longitudinal direction of the heat dissipation material 12. Thereby, the adhesiveness of the surface mold part 3A and the heat dissipation material 14 is improved, and the surface mold part 3A and the heat dissipation material 14 can be prevented from falling off.

Furthermore, as shown in FIG. 10, the heat dissipation material 14 has a through hole 15 in a part thereof. The through-hole 15 is provided at a position that becomes the lowermost portion when, for example, the heat radiating material 14 is installed in the core 3, and the shape in plan view is circular, as in the above-described recess 13. The through holes 15 are formed at a plurality of locations with appropriate intervals in the longitudinal direction of the heat dissipation material 14. Thereby, since the bonding property between the surface mold portion 3A and the mold material inside the heat radiating material 10 is enhanced, the surface mold portion 3A and the heat radiating material 12 can be prevented from falling off.
In addition, the shape of the recessed part 13 or the through-hole 15 formed in the thermal radiation material 14, the number of installation, an installation place, etc. are not limited to the example mentioned above.

  In the heat dissipating material 12 illustrated in FIG. 8 and the heat dissipating material 14 illustrated in FIG. 10, the end portions 12 a and 14 a do not reach the surface of the core 3. Thereby, the mold material inside the heat radiating materials 12 and 14 and the mold material of the surface mold part 3A are coupled. Thereby, even when the heat dissipating materials 12 and 14 have a large area extending over the entire surface of the cavity 4 or when the heat dissipating materials 12 and 14 are installed downward, the surface mold portion 3A and the heat dissipating materials 12 and 14 are removed. The possibility can be further reduced.

  Moreover, although embodiment mentioned above demonstrated the case where the installation position of the heat radiating material 10,12,14 was the inside of the core 3, this invention is not limited to this example. The heat dissipating part may be installed in the vicinity of a position in the mold where the molten metal injected into the cavity becomes hot and becomes hot. At this time, it is desirable that the heat dissipating part is disposed corresponding to the boundary surface with the cavity or extended to the part facing the outside as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 Mold | mold 2 Outer mold | type 2A Step part 2a Inner surface 3,33 Core 3A, 33A Surface mold part 3B Protrusion part 3a, 33a Outer surface 4,34 Cavity 5 Lower mold | type 6 Upper mold | type 7 Pusher part 10,11,12,14 Heat dissipation Material (heat dissipation part)
12a, 14a End 13 Recess 15 Through-hole 20 Hook 21 Wire 30 Molten metal 32 Gas 40 Metal material

Claims (6)

A material having a higher thermal conductivity than the mold material and through which a gas generated in the molten metal passes, and a heat dissipating part disposed in the vicinity of the boundary surface with the cavity into which the molten metal is poured,
The surface mold part, which is made of the mold material and is arranged on the boundary surface side with the cavity than the heat dissipation part,
With mold.   The mold according to claim 1, wherein the heat radiating portion is disposed corresponding to the boundary surface with the cavity.   The mold according to claim 1, wherein the heat radiating portion extends to a portion facing the outside.   The said heat radiating part is installed in the position where the temperature of the surface by the side of the said cavity when the said molten metal is inject | poured becomes lower than melting | fusing point of the said heat radiating part. template.   The mold according to any one of claims 1 to 4, wherein the heat radiating part has a concave shape or a through hole. A step of disposing a heat dissipating part that is higher in heat conductivity than the mold material and through which a gas generated in the molten metal passes, in the vicinity of the interface with the cavity into which the molten metal is poured;
Arranging the surface mold part made of the mold material on the boundary surface side with the cavity rather than the heat dissipation part;
A method for producing a mold having