JP7630366B2 - Casting condition determination method and casting condition determination device - Google Patents

Description

This disclosure relates to a casting condition determination method and a casting condition determination device.

In casting, casting materials containing returned materials are sometimes used. Here, returned materials include parts other than the product that are generated during the production of cast products, or defective products. Returned materials contain a relatively large amount of inclusions, mainly oxides of the material components. For this reason, when casting materials containing returned materials are used, there is a risk that the possibility of manufacturing products with inclusion defects increases.

Patent Document 1 describes that if inclusions are not sufficiently removed from molten aluminum, product quality will decline. Patent Document 1 also describes a method for removing inclusions contained in molten aluminum.

Japanese Unexamined Patent Publication No. 63-199830

By the way, by increasing the mixing ratio of returned material in the casting material, it is possible to reduce material costs. However, it has been difficult to quantitatively evaluate the impact on casting quality when using casting material containing returned material, and for this reason, it is difficult to actively increase the mixing ratio of returned material.

In view of the above, at least one embodiment of the present invention aims to provide a casting condition determination method and casting condition determination device that can increase the mixture ratio of returned materials while suppressing deterioration of product quality.

A casting condition determination method according to at least one embodiment of the present invention includes the steps of:
A method for determining casting conditions using a casting material containing a plurality of types of return materials, comprising the steps of:
The method includes a step of individually determining the upper limit value of the blending amount of each of a plurality of types of return materials having different specific surface areas.

Further, the casting condition determination device according to at least one embodiment of the present invention includes:
A device for determining conditions for casting using a casting material including a plurality of types of return materials, comprising:
The condition determining unit is configured to determine the upper limit value of the blending amount of each of a plurality of types of return materials having different specific surface areas.

According to at least one embodiment of the present invention, a casting condition determination method and casting condition determination device are provided that can increase the mixture ratio of return material while suppressing deterioration of product quality.

FIG. 1 is a schematic configuration diagram of a casting condition determination device according to an embodiment. 1 is a graph showing an example of the correlation between the length of inclusions contained in returned material (vertical axis) and the specific surface area of the returned material (horizontal axis) for an aluminum alloy. 1 is a graph showing the correlation between the K value (vertical axis) and the length of a film-like inclusion contained in a molten metal (horizontal axis) for an aluminum alloy. 1 is a table for explaining an embodiment.

Below, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

The casting condition determination method and casting condition determination device according to some embodiments are a method and device for determining casting conditions, including the upper limit of the blending amount of multiple types of return materials in a casting material, when casting using a casting material that contains multiple types of return materials.

(Regarding returned materials and cast materials)
Returned materials include parts other than the product that are generated during the production of a casting product (such as runners or risers), or defective products that have been formed into products by casting but are not suitable for use for some reason. Defective products usually have the same shape as the product. Returned materials are also called returned materials or scraps.

In this specification, return materials with different shapes are treated as different types of return materials. For example, a defective product and a runner in a certain area are different types of return materials. A runner in a certain area and a runner in another area are different types of return materials. A runner in a certain area and a runner in the same area are the same type of return materials. Different types of return materials usually have different specific surface areas.

In this specification, specific surface area is the surface area per unit weight of the material (either the returned material described above or the new material described below).

The cast material may include new materials such as ingots in addition to multiple types of returned materials. Typically, the new materials and multiple types of returned materials constituting the cast material contain a common metal component. Alternatively, typically, the main metal components of the new materials and multiple types of returned materials constituting the cast material are the same. Alternatively, typically, the compositions of the metal components of the new materials and multiple types of returned materials constituting the cast material are approximately the same.

The casting material, including new materials and/or multiple types of returned materials, may be aluminum or an alloy containing aluminum as the main component (aluminum alloy).

(Configuration of casting condition determining device)
1 is a schematic diagram of a casting condition determination device according to an embodiment of the present invention. As shown in FIG. 1, the casting condition determination device 10 includes a total specific surface area calculation unit 12 and a condition determination unit 14.

The total specific surface area calculation unit 12 is configured to calculate the total specific surface area of the entire cast material including the multiple types of returned materials based on the respective blend amounts (provisional blend amounts) of the multiple types of returned materials and/or new materials in the cast material. Here, the multiple types of returned materials have different specific surface areas.

The total specific surface area calculation unit 12 may be configured to acquire the blending amount of each of the multiple types of returned materials and/or new materials input from the input unit 20 (keyboard or mouse, etc.). The total specific surface area calculation unit 12 may be configured to acquire the specific surface area of each of the multiple types of returned materials and/or new materials input from the input unit 20 or stored in advance in the memory unit 22 (main memory device or auxiliary memory device, etc.). The total specific surface area calculation unit 12 may be configured to calculate the total specific surface area of the entire cast material including the multiple types of returned materials based on the blending amount and/or specific surface area of each of the multiple types of returned materials acquired in this manner. The specific surface area of each material (multiple types of returned materials and/or new materials) may be calculated from a CAD (computer-aided design) model of the mold used in casting or the cast product.

The condition determination unit 14 is configured to individually determine the upper limit value of the blending amount of multiple types of return materials having different specific surface areas. The condition determination unit 14 may be configured to determine the upper limit value of the blending amount of each of the multiple types of return materials based on the total specific surface area of the entire cast material calculated by the total specific surface area calculation unit 12.

The casting conditions, including the upper limit values of the blending amounts of each of the multiple types of return materials determined by the condition determination unit 14, may be output to the output unit 24 (e.g., a display, etc.).

The casting condition determination device 10 includes a computer equipped with a processor (CPU, etc.), a main storage device (memory device; RAM, etc.), an auxiliary storage device, an interface, etc. The casting condition determination device 10 is configured to receive signals from the input unit 20 or the storage unit 22 via the interface. The processor is configured to process the signals received in this manner. The processor is also configured to process a program deployed in the main storage device. This realizes the functions of each of the above-mentioned functional units (total specific surface area calculation unit 12 and condition determination unit 14).

The processing contents of the casting condition determination device 10 are implemented as a program executed by a processor. The program may be stored, for example, in an auxiliary storage device. When the programs are executed, these programs are deployed in a main storage device. The processor reads the program from the main storage device and executes the instructions contained in the program.

The above-mentioned memory unit 22 may include a main memory or auxiliary memory of the computer constituting the casting condition determination device 10, or the memory unit 22 may include a remote memory device connected to the computer via a network.

(Casting condition determination flow)
Next, a casting condition determination method according to some embodiments will be described in more detail. Note that, although the casting condition determination method according to one embodiment will be described below using the above-mentioned casting condition determination device 10, in some embodiments, a part or all of the procedures described below may be performed using another device or manually.

Here, as an example, we will explain the case where a casting material consisting of an ingot (new material), return material A, and return material B is used. Return material A and return material B are different types of return materials with different shapes.

First, the total specific surface area calculation unit 12 acquires the provisional blend amounts (weights) of each material (ingot, return material A, and return material B). The provisional blend amounts of each material may be input by the operator via the input unit 20, and the total specific surface area calculation unit 12 may acquire the blend amounts of each material input via the input unit 20. Here, the provisional blend amounts (weights) of the ingot, return material A, and return material B acquired by the total specific surface area calculation unit 12 are Wn', WA', and WB', respectively.

The total specific surface area calculation unit 12 also acquires the specific surface area of each material (ingot, return material A, and return material B). The specific surface area of each material may be stored in advance in the memory unit 22. The specific surface area of each material can be calculated from a CAD model of the mold used in casting or the cast product. Here, the specific surface areas of the ingot, return material A, and return material B acquired by the total specific surface area calculation unit 12 are designated as Sn, SA, and SB, respectively.

Next, the total specific surface area calculation unit 12 calculates the total specific surface area of the entire cast material including each material (ingot, returned material A, and returned material B) based on the blending amount and specific surface area of each material obtained as described above. The total specific surface area S _ALL of the entire cast material is obtained by dividing the sum of the surface areas of each material by the total weight, and can be expressed by the following formula (A).
S _ALL = (Sn×Wn'+SA×WA'+SB×WB')/(Wn'+WA'+WB')...(A)

Next, the condition determining unit 14 determines the upper limit value of the blending amount of each of the multiple types of returned materials (returned material A and returned material B) based on the above-mentioned total specific surface area S _ALL calculated by the total specific surface area calculating unit 12.

The condition determining unit 14 may determine the upper limit value WA_U of the blending amount of the return material A and the upper limit value WB_U of the blending amount of the return material B so that the total specific surface area S _ALL satisfies the criteria.

As a result of careful investigation by the inventors, it was found that for casting materials such as ingots (new materials) and returned materials, there is a correlation between the specific surface area of each material and the amount of inclusions contained in the material. In this regard, according to the above-mentioned method, the upper limit values (WA_U and WB_U) of the blending amounts of two or more types of returned materials (returned material A and returned material B) with different specific surface areas are determined independently. Therefore, by appropriately setting the upper limit value of the blending amount of each returned material according to each specific surface area, it is possible to increase the blending ratio of returned materials in the casting material while suppressing deterioration of product quality.

In addition, the total specific surface area of the entire cast material can be an index of the amount of inclusions contained in the entire cast material. Therefore, as described above, by determining the upper limit value of each of the blending amounts of the multiple types of returned materials (return material A and return material B) so that the total specific surface area S _ALL of the entire cast material including the multiple types of returned materials satisfies the criteria, it is possible to increase the blending ratio of the returned materials in the cast material while more reliably suppressing the deterioration of product quality.

In one embodiment, the condition determination unit 14 determines the upper limit of the blending amount of each of the multiple types of return materials so that the total specific surface area S _ALL is equal to or less than the threshold value S _th . For example, in the above example, when the calculated total specific surface area S _ALL is equal to or less than the threshold value S th, the provisional blending amounts WA and WB of the return materials A and B used in the calculation of the total specific surface area S _ALL may be determined as the upper limit values WA_U and WB_U of the blending amounts of the return materials A and B, respectively.

The threshold value _Sth compared with the total specific surface area _SALL can be determined based on the correlation between an index indicating the amount of inclusions contained in the returned material and the specific surface area of the returned material. The index indicating the amount of inclusions contained in the returned material may be, for example, a value based on the peripheral length (hereinafter also referred to as the inclusion length) of inclusions (film-like inclusions) remaining on a filter when the molten returned material is filtered through the filter.

Here, FIG. 2 is a graph showing an example of the correlation between the length of inclusions (vertical axis) contained in returned material (and new material) per unit weight and the specific surface area (horizontal axis) of returned material (and new material) for aluminum alloys. The length of inclusions contained in each returned material (and new material) was measured by PoDFA (Porous Disc Filtration Apparatus) analysis, which is an aluminum molten metal inclusion analysis method. The peripheral length of the inclusions in the graph of FIG. 2 was calculated from the sum of the peripheral lengths measured by filtering the molten metal of each material with a filter, observing the inclusions remaining on the filter with a microscope, and measuring the peripheral length of the film-like inclusions contained in the field of view of the microscope. The length of inclusions contained in the material (returned material or new material) per unit weight is an index that indicates the amount of inclusions contained in each material per unit weight.

Figure 3 is a graph showing the correlation between the K value (vertical axis) and the length of film-like inclusions (horizontal axis) contained in the molten metal for aluminum alloys. The K value is an index of the cleanliness of the molten metal, and can be measured by the method specified in JIS H 0523:2020.

As a result of intensive research by the present inventors, as shown in the graph of Figure 2, it was found that there is a correlation between the specific surface area of each material (returned material and new material) constituting the cast material and the amount of inclusions contained in the material, and that the relationship is roughly proportional. Therefore, the total specific surface area of the entire cast material consisting of multiple returned materials and/or new materials can be an index showing the amount of inclusions contained in the entire cast material. Note that the correlation between each material (multiple types of returned materials and new materials) and the amount of inclusions contained in these materials was previously unknown, and the fact that the above-mentioned correlation exists between the specific surface area of each material and the amount of inclusions is a new finding by the present inventors.

It is generally known that for aluminum and aluminum alloys, if the K value is 1 or less, the cleanliness of the molten metal is sufficient and a good quality casting can be obtained. Also, based on the approximation curve obtained from the graph in Figure 3, it can be seen that if the length of inclusions contained in the molten metal per unit weight is approximately 3.5 mm/kg or less, the K value will be 1 or less.

Therefore, for a cast material including a plurality of returned materials (and/or new materials), if the compounding ratio of each material is determined based on the graph obtained in Fig. 2 so that the total specific surface area of the entire cast material having an inclusion length per unit weight of about 3.5 mm/kg or less is obtained, the K value of the molten metal of the cast material will be 1 or less, and the quality of the casting obtained from the cast material will be good. That is, the above-mentioned threshold value _Sth to be compared with the total specific surface area _SALL in the above example may be the total specific surface area of the cast material having an inclusion length per unit weight of 3.5 mm/kg.

The inventors have found from the graph of FIG. 2 that in a certain type of aluminum alloy, the relationship between the inclusion length L _A (mm/kg) and the material specific surface area S (mm ² /g) is expressed by the following formula (B).
L _A =0.04×S+0.97…(B)
Based on this formula, the threshold value S _th to be compared with the total specific surface area S _ALL in the above example is 63.25 (mm ² /g).

In this way, based on the correlation between the index indicating the amount of inclusions contained in the returned material (inclusion length per unit weight) and the specific surface area of the returned material, a threshold value to be compared with the total specific surface area of the entire cast material can be easily and appropriately determined.

Figure 4 is a table for explaining the examples. The total specific surface area was calculated for cast materials (Examples 1 to 5) consisting of multiple types of return materials (feeder A, feeder B, runner C, defective product Q) and/or new materials (ingots). In addition, thermal analysis measurements were performed for each cast material (Examples 1 to 5) to evaluate the amount of inclusions.

(Composition of each ingredient)
As the casting materials of Examples 1 to 5, casting materials having the compounding ratios (by weight) shown in the "Raw Materials" column in the table of FIG. 4 were prepared.

(Calculation of surface area of each material and total specific surface area)
For the cast materials of Examples 1 to 5, the surface area was calculated based on the specific surface area of each material, and the total specific surface area of the entire cast material was calculated using the calculation results. The surface area and total specific surface area of each material are as shown in the "Surface area" and "Total specific surface area" columns in the table of Figure 4. The specific surface areas of each material are as follows: ingot: 33 mm ² /g, feeder A: 33 mm ² /g, feeder B: 66 mm ² /g, runner C: 55 mm ² /g, defective product Q: 108 mm ² /g.

When comparing the total specific surface areas of the cast materials of Examples 1 to 5 with the threshold value S _th (63.25 mm ² /g) calculated from the above formula (B), the total specific surface areas of the cast materials of Examples 1 to 4 are below the threshold value, while the total specific surface area of the cast material of Example 5 is above the threshold value.

The inclusion length (length of the film-like inclusion) can be estimated based on the total specific surface area for the cast materials of Examples 1 to 5, using the above formula B. The inclusion length estimated in this way is as shown in the "Inclusion Length" column in the table of Figure 4.

(Evaluation of the amount of inclusions)
The amount of inclusions was evaluated by thermal analysis for the cast materials of Examples 1 to 5. The thermal analysis was performed by pouring the molten metal into a predetermined mold for each of the cast materials of Examples 1 to 5, and measuring the time it took for the metal to solidify from a predetermined temperature (solidification time; the time it took for the slope of the temperature change over time to change). Here, the longer the solidification time of the molten metal, the greater the amount of inclusions.

For the cast materials of Examples 1 to 4, the solidification time of the molten metal was equal to or less than the specified value, and for the cast material of Example 5, the solidification time of the molten metal exceeded the specified value. In other words, it was confirmed that the cast materials of Examples 1 to 4, whose total specific surface area was equal to or less than the above-mentioned threshold, had a relatively small amount of inclusions, and that the cast material of Example 5, whose total specific surface area exceeded the above-mentioned threshold, had a relatively large amount of inclusions.

These results show that the threshold value (63.25 ^mm2 /g) of the total specific surface area of the cast material set for aluminum alloys is appropriate, and that by determining the upper limit value of each returned material based on this threshold value, castings of good quality can be obtained.

The casting materials of Examples 1 to 4 have a total mixture ratio of returned materials of 50% to 100%. Conventionally, the mixture ratio of returned materials in casting materials is about 20% or less. Therefore, by determining the upper limit of the mixture amount of each returned material according to the above-mentioned method, it is possible to increase the mixture ratio of returned materials while suppressing quality degradation, as shown in the examples.

The contents described in each of the above embodiments can be understood, for example, as follows:

(1) A casting condition determination method according to at least one embodiment of the present invention includes:
A method for determining casting conditions using a casting material containing a plurality of types of return materials, comprising the steps of:
The method includes a step of individually determining the upper limit value of the blending amount of each of a plurality of types of return materials having different specific surface areas.

As a result of intensive research by the inventors, it was found that for casting materials such as ingots (new materials) and returned materials, there is a correlation between the specific surface area of each material and the amount of inclusions contained in the material. In this regard, in the above method (1), the upper limit values of the blending amounts of two or more types of returned materials with different specific surface areas are determined independently. Therefore, by appropriately setting the upper limit value of the blending amount of each returned material according to each specific surface area, it is possible to increase the blending ratio of returned materials in the casting material while suppressing deterioration of product quality.

(2) In some embodiments, in the method of (1),
Based on the blending amount of each of the multiple types of return materials, the total specific surface area of the entire casting material including the multiple types of return materials is calculated, and an upper limit value of the blending amount of each of the multiple types of return materials is determined so that the total specific surface area satisfies a criterion.

According to the findings of the inventors, the total specific surface area of the entire cast material can be an indicator of the amount of inclusions contained in the entire cast material. According to the method (2) above, the upper limit value of the blending amount of each of the multiple types of returned materials is determined so that the total specific surface area of the entire cast material including the multiple types of returned materials satisfies the criteria. Therefore, by blending each returned material according to the upper limit value determined in this way, it is possible to increase the blending ratio of the returned materials in the cast material while more reliably suppressing deterioration in product quality.

(3) In some embodiments, in the method of (2),
The upper limit of the blending amount of each of the plurality of types of returned materials is determined so that the total specific surface area is equal to or less than a threshold value.

According to the method (3) above, the upper limit of the blending amount of each of the multiple types of returned materials is determined so that the total specific surface area of the entire cast material including the multiple types of returned materials is equal to or less than a threshold value. Therefore, by blending each returned material according to the upper limit determined in this way, it is possible to increase the blending ratio of the returned materials in the cast material while more reliably suppressing deterioration in product quality.

(4) In some embodiments, in the method of (3),
The threshold value is determined based on the correlation between an index indicating the amount of inclusions contained in the returned material and the specific surface area of the returned material.

According to the method (4) above, a threshold value to be compared with the total specific surface area of the entire cast material can be easily and appropriately determined based on the correlation between an index indicating the amount of inclusions contained in the returned material and the specific surface area of the returned material.

(5) In some embodiments, in the method of (4),
The index is a value based on the peripheral length of inclusions remaining on a filter when the molten returned material is filtered through the filter.

For multiple types of returned materials, the perimeter length of the inclusions remaining on the filter when the molten material is filtered through a filter can be an indicator of the amount of inclusions contained in each returned material. According to the method of (5) above, the upper limit of the blending amount of each returned material can be appropriately determined using an indicator based on the perimeter length of the inclusions remaining on the filter when the molten returned material is filtered through a filter.

(6) In some embodiments, in any of the methods (1) to (5) above,
The ratio of the total amount of the plurality of types of return materials to the total amount of the cast material is 50% or more and 100% or less.

Conventionally, the amount of returned material in the casting material is usually about 20% or less. According to the method (6) above, the upper limit of the amount of each of the multiple types of returned material is determined according to the method described in (1) above, so that even if the returned material is added at a high ratio, for example 50% or more, deterioration of product quality can be effectively suppressed.

(7) In some embodiments, in any of the methods (1) to (6) above,
The casting material is aluminum or an aluminum alloy.

According to the findings of the present inventors, for casting materials containing aluminum, there is a relatively strong correlation between the specific surface area of each material (new material and returned material) and the amount of inclusions contained in the material. According to the method of (7) above, for casting materials of aluminum or aluminum alloy, the upper limit values of the blending amounts of multiple types of returned materials are determined independently according to the method of (1) above. Therefore, by appropriately setting the upper limit value of the blending amount of each returned material according to each specific surface area, it is possible to increase the blending ratio of returned materials in the casting material while suppressing deterioration of product quality.

(8) At least one embodiment of the casting condition determination device (10) of the present invention comprises:
A device for determining conditions for casting using a casting material including a plurality of types of return materials, comprising:
The apparatus includes a condition determining section (14) configured to determine the upper limit values of the blending amounts of a plurality of types of return materials having different specific surface areas, individually.

In the above configuration (8), the upper limit of the blending amount of two or more types of return materials with different specific surface areas is determined independently. Therefore, by appropriately setting the upper limit of the blending amount of each return material according to its respective specific surface area, it is possible to increase the blending ratio of return materials in the casting material while suppressing deterioration of product quality.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes variations on the above-described embodiments and appropriate combinations of these embodiments.

In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
In addition, in this specification, the expressions "comprise,""include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements.

10 Casting condition determination device 12 Total specific surface area calculation unit 14 Condition determination unit 20 Input unit 22 Storage unit 24 Output unit

Claims (4)

A method for determining a casting condition for a metal or alloy casting product using a casting material including a plurality of types of return materials having different specific surface areas generated during the production of the casting product , comprising:
The specific surface area is the surface area per unit weight,
Calculating a total specific surface area of the entire cast material including the plurality of types of return materials based on the blending amounts of the plurality of types of return materials ;
and determining an upper limit value of the blending amount of each of the plurality of types of return materials so that the total specific surface area is equal to or less than a threshold value ;
The threshold value is determined based on a correlation between an index indicating the amount of inclusions contained in the returned material and a specific surface area of the returned material,
The index is a value based on the peripheral length of inclusions remaining on a filter when the molten returned material is filtered through the filter.
How to determine casting conditions. 2. The method for determining casting conditions according to claim 1 , wherein a ratio of a total amount of the plurality of types of return materials to a total amount of the cast material is 50% or more and 100% or less. 3. The method for determining casting conditions according to claim 1, wherein the casting material is aluminum or an aluminum alloy. A device for determining conditions for casting a metal or alloy cast product using a cast material including a plurality of types of return materials having different specific surface areas generated during the production of the cast product, comprising:
The specific surface area is the surface area per unit weight,
a total specific surface area calculation unit that calculates a total specific surface area of the entire casting material including the plurality of types of return materials based on the blending amounts of the plurality of types of return materials ;
A condition determination unit configured to determine an upper limit value of the blending amount of each of the plurality of types of return materials so that the total specific surface area is equal to or less than a threshold value ,
The threshold value is determined based on a correlation between an index indicating the amount of inclusions contained in the returned material and a specific surface area of the returned material,
The index is a value based on the peripheral length of inclusions remaining on a filter when the molten returned material is filtered through the filter.
Casting condition determination device.

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