JP2019150836A - Method for producing casting, and metallic component - Google Patents

Abstract

To provide a method for producing a casting easily producible and having excellent characteristics in one part, and a metallic component.SOLUTION: A method for producing a casting comprises: an additive arrangement step; and a casting step. In the additive arrangement step, an additive is arranged at a part of a region which is the internal space of a mold and is in contact with a molten metal made to flow. In the casting step, the molten metal of the metal is made to flow into the mold, and a casting having a part in which a part of the molten metal and the additive are mixed is cast.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a cast product and a metal part.

  The manufacturing method of a cast product forms metal parts by solidifying a molten metal poured into a mold in the mold. According to the method of manufacturing a cast product, the metal part to be molded has a high degree of freedom, and even a metal part having a complicated shape such as a scroll part having a spiral tooth portion used in a scroll compressor can be easily formed. can do.

  Since the spiral tooth portion of the scroll component is repeatedly subjected to bending stress during operation, it is required to improve characteristics including fatigue strength. It is known that when a pearlite-promoting element such as copper, tin, manganese, or chromium is added to a spheroidal graphite cast iron material used as a casting material, the ratio of the pearlite structure in the base structure increases and the fatigue strength increases. When a pearlite-promoting element is added to a spheroidal graphite cast iron material, not only fatigue strength but also tensile strength and hardness are increased, and workability is impaired.

  As a technique for improving fatigue strength without impairing workability, Non-Patent Document 1 describes a method of adding 3 to 4.5 mass% of an additive containing silicon to spheroidal graphite cast iron to increase the fatigue strength of the entire component. Disclosure.

  Patent Documents 1 to 3 disclose a method of performing heat treatment or shot peening on a portion where the fatigue strength is improved as a technology for improving the fatigue strength of only the tooth portion of a scroll part made of spheroidal graphite cast iron. .

Japanese Patent No. 4526616 Japanese Patent No. 5088912 Japanese Patent No. 5614887

The Japan Foundry Engineering Society The 162nd National Lecture Meeting Summary of Speech 58 pages 3.2

  In the method of adding silicon disclosed in Non-Patent Document 1, since the molten metal of which the silicon content is adjusted is poured into a mold and cast, the fatigue strength of the entire part is improved. In this case, the silicon amount needs to be 3 to 4.5% for the entire metal part. For this reason, the smaller the proportion of the spiral tooth portion for which fatigue strength is required, the more wasteful silicon is added, which increases the material cost.

  In the methods for improving the fatigue strength of metal parts by heat treatment or shot peening disclosed in Patent Documents 1 to 3, a processing step for improving the fatigue strength is required, so that the time and cost for manufacturing increase. For this reason, there is a problem that it is not easy to improve some characteristics of the metal part.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a cast product and a metal part which can be easily manufactured and have excellent characteristics.

  In order to achieve the above object, the method for producing a cast product of the present invention includes an additive arranging step and a casting step. In the additive placement step, the additive is placed in a part of the inner space of the mold and in contact with the poured molten metal. In the casting process, a molten metal is poured into a mold, and a casting in which a part of the molten metal and an additive are mixed is cast.

  According to the present invention, the additive is disposed in the inner space of the mold, and a part of the molten metal and the additive are mixed to improve characteristics such as fatigue strength of a part of the metal part. Therefore, it is possible to provide a method for manufacturing a cast product and a metal part which can be easily manufactured and have excellent characteristics in a part.

The figure which shows the scroll components which concern on Embodiment 1 of this invention. The flowchart which shows the manufacturing method of the casting based on Embodiment 1 of this invention. The figure which shows the casting_mold | template concerning Embodiment 1 of this invention. Sectional drawing of the lower mold | type which comprises the casting_mold | template which concerns on Embodiment 1 of this invention Sectional drawing of the lower mold | type which comprises the casting_mold | template which concerns on Embodiment 2 of this invention Sectional drawing of the lower mold | type which comprises the casting_mold | template which concerns on Embodiment 3 of this invention The expanded sectional view of the lower mold which constitutes the mold concerning Embodiment 3 of the present invention Sectional drawing of the lower mold | type which comprises the casting_mold | template concerning Embodiment 4 of this invention The figure which shows the casting_mold | template concerning Embodiment 5 of this invention. Sectional drawing of the lower mold | type which comprises the casting_mold | template concerning Embodiment 5 of this invention Sectional drawing of the lower mold | type which comprises the casting_mold | template concerning Embodiment 6 of this invention Sectional drawing of the lower mold | type which comprises the casting_mold | template which concerns on Embodiment 7 of this invention Sectional drawing of the lower mold | type which comprises the casting_mold | template which concerns on Embodiment 8 of this invention

  Hereinafter, a method for producing a cast product and a metal part according to an embodiment of the present invention will be described.

(Embodiment 1)
As shown in FIG. 1, a scroll component 100, which is a metal component according to an embodiment of the present invention, includes a base portion 101 and a spiral tooth portion 102 having a spiral wall body standing on the base portion 101. And comprising. The scroll compressor includes two scroll parts 100. One scroll component 100 is fixed. The other scroll component 100 is arranged such that the spiral tooth portion 102 is engaged with the spiral tooth portion 102 of one fixed scroll component 100. When the other scroll component 100 swings, the air in the region surrounded by the two opposing spiral teeth 102 is compressed. In the scroll compressor, the spiral tooth portion 102 oscillates while rubbing with the other spiral tooth portion 102 during operation, and a bending stress is repeatedly applied to the spiral tooth portion 102. Requires fatigue strength. On the other hand, the base portion 101 is a portion having a function of fastening with other parts and a function of transmitting a swinging force, and requires workability rather than fatigue strength.

  The scroll component 100 is made of spheroidal graphite cast iron in order to obtain high strength. Spheroidal graphite cast iron contains spherical graphite. The silicon content of the spiral tooth portion 102 is higher than the silicon content of the base portion 101.

  Next, a method for manufacturing a cast product according to the present embodiment will be described by taking the scroll component 100 as an example.

  As shown in FIG. 2, the casting product manufacturing method according to the present embodiment includes a mold creation step (step S <b> 101) for creating the mold 10 and an additive placement step for placing the additive 31 in the internal space of the mold 10. (Step S102), a casting step (Step S103) for pouring the molten metal into the mold 10, and a cooling step (Step S104) for cooling the molten metal.

  In the mold making process (step S101), the model is covered with a mixture of the mold sand and the binder, the mixture covering the model is cured, the model is taken out of the cured mixture, and the mold 10 used for casting is obtained. . Silica sand is used as the mold sand. As the binder, any of inorganic materials such as clays, cement and water glass, organic materials such as phenol resin and furan resin, or a mixture thereof is used. The mold 10 includes an upper mold 11 and a lower mold 12 as shown in FIG. By combining the upper mold 11 and the lower mold 12 that are respectively created, it functions as one mold. The mold 10 includes a product shape portion 21 for creating a shape of a metal part, a spout 22 for pouring a molten metal, a runner 23 serving as a flow path for the molten metal, and a molten metal melt as a product shape portion. And a weir 24 led to 21. The product shape portion 21 has a space having the same shape as the shape of the scroll component 100.

  In the additive placement step (step S102), as shown in FIG. 4, the additive 31 is placed in the portion 25 where the spiral tooth portion 102 of the scroll component 100 is formed. Additive 31 includes a powdery material containing silicon. The additive 31 disposed in the mold 10 is close to room temperature. If an amount of the additive 31 that lowers the temperature of the poured molten metal is disposed, the additive 31 does not dissolve in the molten metal and remains as an impurity in the metal part, which may cause casting defects. For this reason, it is desirable to use a small amount of the additive 31 having a high silicon content, such as silicon or silicon carbide. It is preferable to contain any of iron silicide or a mixture thereof.

  In the casting process (step S103), a molten metal is poured from the gate 22 shown in FIG. 3, and a casting in which a part of the molten metal and the additive 31 are mixed is cast. As the molten metal, one containing a component for casting spheroidal graphite cast iron is used. When the molten metal is poured from the spout 22, the molten metal flows through the runner 23 and flows from the weir 24 into the product shape portion 21. When the molten metal flows into the portion 25 where the spiral tooth portion 102 is formed, the additive 31 is melted by the molten metal, the molten metal and the additive 31 are mixed, and the additive 31 is disposed. 25, a region having a high concentration of the additive 31 is formed. Accordingly, the concentration of silicon contained in the additive 31 is higher in the spiral tooth portion 102 than in the base portion 101.

  In the cooling step (step S104), the molten metal poured into the mold 10 is cooled and solidified. Thereafter, the mold 10 is broken and the scroll component 100 is taken out.

  As described above, according to the method for manufacturing a cast product of the present embodiment, it is possible to obtain the scroll component 100 in which the silicon concentration in the spiral tooth portion 102 is higher than the silicon concentration in the base portion 101. Since the spiral tooth portion 102 is made of spheroidal graphite cast iron having a high silicon concentration, it has a high fatigue strength. Since the base portion 101 is made of spheroidal graphite cast iron having a lower silicon content than the spiral tooth portion 102, the base portion 101 has excellent workability. Further, since the silicon concentration is high only in the spiral tooth portion 102, the amount of silicon used can be reduced as compared with the case where the silicon concentration of the entire scroll component 100 is increased. Therefore, it is possible to easily obtain the scroll component 100 having excellent characteristics necessary for the spiral tooth portion 102 and the base portion 101.

(Embodiment 2)
In the second embodiment, an example in which the solid additive 31 is embedded in the portion 25 where the spiral tooth portion 102 of the product shape portion 21 of the mold 10 is formed in the additive placement step (step S102) will be described. .

  As shown in FIG. 5, it is difficult to dispose solid matter such as the wall surface or ceiling portion of the mold 10 by embedding the additive 31 in the mold 10 and disposing the additive 31 in the portion 25 where the spiral tooth portion 102 is formed. Also in the place, the additive 31 can be arranged. It is possible to dispose the additive 31 regardless of the orientation of the product shape portion 21 in the mold 10, that is, the casting posture. Further, as in the present embodiment, the additive 31 is embedded in the bottom surface and the side surface of the portion 25 of the product shape portion 21, so that vibration occurs during the transfer of the mold 10, or the mold 10 in the tilt casting method. Even when the inclination is added, the unintended movement of the additive 31 can be prevented, and the additive 31 can be reliably added to the spiral tooth portion 102.

  In casting using a sand mold for the mold 10, a casting frame is placed on a surface plate to which models such as the product shape portion 21, the gate 22, the runner 23, and the weir 24 are attached, and the molding sand is placed in the casting frame. The mold 10 is formed by removing the model and the surface plate after the sand has hardened. Here, the mold sand is placed in a state where the additive 31 is disposed on the surface of the model of the product shape portion 21, and after the sand is solidified, the model and the surface plate are taken out and molded, so that the work after molding is difficult. It is possible to add the additive 31 to a position aimed at the thin-walled portion.

(Embodiment 3)
In the third embodiment, in the additive placement step (step S102), as shown in FIGS. 6 and 7, the fitting portion 33, which is a convex portion formed on the solid additive 31, is replaced with the product shape portion of the mold 10. It fits in the to-be-fitted part 34 which is a recessed part formed in the top part which exists between 21 groove parts, and the additive 31 is fixed.

  By fitting the fitting portion 33 formed on the additive 31 and the fitted portion 34 formed on the mold 10 and placing the additive 31, a solid addition is added to the top of the product shape portion 21 of the lower mold 12. The agent 31 can be disposed stably. Further, even when vibration occurs during transfer after completion of the mold 10, unintentional movement of the additive 31 can be prevented, and the additive 31 can be reliably added to the spiral tooth portion 102. The fitting part 33 and the to-be-fitted part 34 should just be a shape which mutually fits, the fitting part 33 may be concave shape and the to-be-fitted part 34 may be convex shape. The fitting portion 33 and the fitted portion 34 may be wavy uneven portions whose phases are shifted by a half cycle, or zigzag uneven portions.

  Further, not only the fitted portion 34 is formed in the product shape portion 21 but the fitted portion 34 may be formed on the wall surface or the ceiling portion of the mold 10 and the additive 31 may be disposed. In this case, since the fitted portion 34 has a so-called undercut shape, it cannot be easily created with a model that is extracted in one direction, but a split model is adopted, and only the fitted portion 34 on the wall surface is changed in the extraction direction of the model. Can be created. In addition, it is possible to form by sand-type laminated molding in which sand is spread one layer at a time and a binder is applied only to a necessary portion and hardened. The mold 10 having the fitted portion 34 on the wall surface can be easily molded without impairing workability during molding by inputting the three-dimensional shape data into the molding apparatus.

(Embodiment 4)
In the first to third embodiments, the example in which the additive 31 that is a solid material containing silicon is arranged has been described. However, in the fourth embodiment, the dispersion tooth 32 containing the additive 31 is dispersed in the spiral tooth portion 102. The example which arrange | positions the additive 31 by apply | coating to the part 25 formed is demonstrated.

  In the additive placement step (step S102), the additive 31 is mixed with the dispersion 32, and the dispersion 32 containing the additive 31 is swirled with an application tool such as a brush or brush as shown in FIG. It applies to the part 25 in which 102 is formed. By mixing and applying the additive 31 to the dispersion 32, it is possible to dispose the additive 31 even in places where it is difficult to dispose the powder, such as a wall surface or a ceiling portion in the mold 10. This eliminates the restriction on the position of the additive 31 depending on the orientation of the product in the mold 10, that is, the casting posture, and has an effect that a portion having excellent characteristics can be freely selected in the metal product.

  Examples of the solvent constituting the dispersion liquid 32 include hexane, benzene, toluene, ethanol, methanol, formic acid, and water. Among these, alcohols such as methanol and ethanol are preferable.

  In the mold 10, a liquid material called a coating mold (Togata) is applied to a portion that is generally in contact with the molten metal. The coating mold is for the purpose of improving the surface properties of the surface of the cast iron part by smoothing the fine irregularities on the surface of the mold 10, or by covering the surface of the mold 10 with the coating material, It is carried out for the purpose of preventing seizure or collapse of the mold 10. The additive 31 is mixed with the coating material to form a dispersion 32 containing the additive 31, and the additive 31 is applied to the portion 25 where the spiral tooth portion 102 is formed with an application tool such as a brush or a brush. The additive 31 can be added to the surface of the mold 10 without increasing the number of steps for placement. Further, at the casting site, vibration is applied to the mold 10 when it is transferred by a crane or a conveyor after the mold 10 is completed. By applying the dispersion liquid 32 containing the additive 31 to the surface of the mold 10, when the mold 10 is transferred, the unintended movement of the additive 31 is prevented, and the additive 31 is reliably applied to the spiral tooth portion 102. Can be added.

  In addition, an inclined casting method is known as one of methods for producing a cast product. In this method, molten metal is poured into a preliminary chamber in the mold 10, and the mold 10 is inclined from the state to guide the molten metal to the product shape portion 21. In this casting product manufacturing method, if a method of arranging a solid material as the additive 31 is applied, the direction in which gravity is applied in the mold 10 when the mold 10 is tilted changes, so that the solid additive 31 moves and is aimed. There is a possibility that the additive 31 is not added to the spot. As in the present embodiment, by applying the dispersion liquid 32 containing the additive 31 to the portion 25 where the spiral tooth portion 102 is formed, the spiral tooth portion 102 can be reliably applied even in the inclined casting method. Additive 31 can be added.

(Embodiment 5)
In the fifth embodiment, as shown in FIG. 9, the lower mold 12 includes a main mold 13 and a core 14, and a product shape portion 21 is formed on the core 14. To 4.

  The core 14 refers to a combination type element that forms a part of a product shape, and is used when forming a hollow portion or a punched hole of a cast product. Further, for a plurality of cast products having portions having common dimensions and shapes, a main model is formed by forming a common portion with the main mold 13 and forming a different portion with the core 14. It is also used for standardization of molding and standardization of molding work.

  In the additive placement step (step S102), as shown in FIG. 10, the powdery additive 31 is placed in the groove provided in the portion 25 of the product shape portion 21 formed in the core. In the casting process (step S103), when the molten metal flows into the product shape portion 21, the additive 31 is melted by the molten metal, and the region where the additive 31 is disposed is a region where the concentration of the additive 31 is high. Is formed.

  In general, the core is smaller than the main mold, and the molding cycle is often shortened. By arranging the additive 31 in the core 14 as in the present embodiment, the molding of the core 14 and the placement of the additive 31 can be performed in parallel with the molding of the main mold 13. There is an effect that the time required for completion can be shortened.

(Embodiment 6)
In the sixth embodiment, an example in which the lower mold 12 includes a main mold 13 and a core 14 and the additive 31 is embedded in the core 14 of the lower mold 12 will be described. The point that the lower mold 12 includes the main mold 13 and the core 14 is the same as in the fifth embodiment. The method of embedding the additive 31 in the core 14 of the lower mold 12 is the same as in the second embodiment.

  In the present embodiment, as shown in FIG. 11, a solid additive 31 is embedded in the bottom surface and side surface of the portion 25 of the product shape portion 21 in the core 14 of the lower mold 12. By embedding the additive 31 in the mold 10, it is possible to dispose the additive 31 even in places where it is difficult to dispose solid matter such as a wall surface or a ceiling portion in the mold 10.

  In the molding of the core 14, sand for casting is put into a hollow core mold, and after the sand is solidified, the core mold is opened to take out the completed core. Here, it is possible to embed the additive in the surface of the core 14 without roughening the surface of the core 14 after molding by inserting sand with the additive 31 placed on the surface of the core mold. Is possible. In general, the core 14 is smaller than the main mold 13 and excellent in handling. Therefore, the structure in which the additive 31 is embedded in the core 14 makes it possible to embed the additive 31 in the main mold 13. This has the effect of improving workability. Other features and advantages are the same as in the second embodiment.

(Embodiment 7)
In the seventh embodiment, an example will be described in which the lower mold 12 includes a main mold 13 and a core 14, is fitted to a fitted portion 34 formed on the core 14, and the additive 31 is fixed. The point that the lower mold 12 includes the main mold 13 and the core 14 is the same as in the fifth and sixth embodiments. As shown in FIG. 12, the fitting portion 33 formed in the solid additive 31 is fitted into the fitted portion 34 which is a recess formed in the portion 25 of the product shape portion 21, and the additive 31 is fixed. . Other features and advantages are the same as in the third embodiment.

(Embodiment 8)
In the eighth embodiment, an example in which the lower mold 12 includes the main mold 13 and the core 14 and the dispersion liquid 32 including the additive 31 is applied to the core 14 will be described. The point that the lower mold 12 includes the main mold 13 and the core 14 is the same as in the fifth to seventh embodiments. The method for applying the dispersion 32 containing the additive 31 is the same as in the fourth embodiment.

  In the present embodiment, in the additive placement step (step S102), as shown in FIG. 13, the dispersion liquid 32 containing the additive 31 is applied to the portion 25 of the product shape portion 21 in the core 14 by brush or brush. Apply with tools. Since the core 14 is smaller than the main mold 13 and excellent in handling, the core 14 is coated with the dispersion 32 containing the additive 31 to improve the workability at the time of the application work and reduce the work time. There are effects such as reduction and prevention of sand mold collapse due to work mistakes. Furthermore, the core 14 is immersed in a container filled with the dispersion liquid 32 containing the additive 31 by matching the shape and size of the core 14 with the portion 25 where the spiral tooth portion 102 is formed. By doing so, it is possible to include the additive 31 only in a necessary portion. Thereby, there is an effect that the application work with a brush or a brush can be eliminated and the work can be simplified and automated.

(Modification)
In the above-described embodiment, an example in which the mold 10 is obtained by curing mold sand with a binder has been described. The mold 10 may be any mold that can cast the scroll component 100, and may be one that is made of a mold. In this case, metal parts having the same shape can be continuously cast.

  In the above-described embodiment, the example in which the additive 31 containing silicon is added to the spiral tooth portion 102 of the scroll component 100 made of spheroidal graphite cast iron has been described. The additive 31 is not limited to the one containing silicon, and may contain other composition as long as it is a component that gives excellent characteristics, and may contain a pearlite promoting element instead of silicon. When the pearlization promoting element is included, the ratio of the pearlite structure in the base structure increases and the fatigue strength increases. The pearlization promoting element includes any element of tin, manganese, chromium, or a combination of these elements.

  In the above-described embodiment, the example in which the scroll component 100 is made of spheroidal graphite cast iron has been described. The scroll component 100 may be made of an alloy other than the spheroidal graphite cast iron as long as the required strength can be satisfied. The scroll component 100 may be made of an iron alloy other than spheroidal graphite cast iron, a copper alloy, an aluminum alloy, or a nickel alloy.

  In the above embodiment, an example in which the scroll component 100 is cast has been described. However, a metal component other than the scroll component 100 may be cast. Metal parts include those having teeth that require properties including strength. A gear is mentioned as a metal component provided with a tooth part, and the tooth | gear of a gear corresponds to a tooth part.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. In other words, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

  10 molds, 11 upper molds, 12 lower molds, 13 main molds, 14 cores, 21 product shape parts, 22 spouts, 23 runners, 24 weirs, 25 parts, 31 additives, 32 dispersions, 33 fitting parts, 34 part to be fitted, 100 scroll part, 101 base part, 102 spiral tooth part

Claims (9)

An additive placement step of placing the additive in a portion of the inner space of the mold that is in contact with the poured molten metal;
A casting step of casting the molten metal into the mold and casting a casting having a portion in which a part of the molten metal and the additive are mixed;
A method for producing a cast product comprising: The mold is a mold for casting a metal part having a tooth portion,
In the additive placement step, the additive is placed in a portion of the mold where the tooth portion is formed.
The method for producing a cast product according to claim 1. The metal component includes a scroll component including the spiral tooth portion having a spiral wall body,
The method for producing a cast product according to claim 2. In the additive placement step, the solid additive is embedded or fitted to a part of the inner wall of the mold and fixed.
The method for producing a cast product according to any one of claims 1 to 3. In the additive placement step, a dispersion containing the additive is applied to a part of the inner wall of the mold.
The method for producing a cast product according to any one of claims 1 to 3. In the additive arranging step, the mold includes a core, and the additive is arranged in a part of the core.
The method for producing a cast product according to any one of claims 1 to 5. A metal part comprising a base part and a tooth part attached to the base part,
The metal part includes a metal and an additive added to the metal,
The content of the additive in the tooth part is higher than the content of the additive in the base part,
Metal parts. The metal component includes a scroll component including the base portion and the spiral tooth portion having a spiral wall body standing on the base portion.
The metal part according to claim 7. The metal part includes silicon added to spheroidal graphite cast iron and spheroidal graphite cast iron,
The concentration of silicon in the tooth portion is higher than the concentration of silicon in the base portion,
The metal part according to claim 7 or 8.

Images