METHOD FOR PROCESSING METAL-CAST ARTICLE

Abstract

A method for processing a metal-cast article according to an aspect of the present invention includes a correcting step of starting to pressurize the metal-cast article by a press machine (10, 20) before a temperature of the metal-cast article 40 decreases to 200° C. or lower after casting is finished. Distortion can be accurately removed in a correction of a metal-cast article. Further, since there is no need to heat the metal-cast article again for the correction, the productivity and energy efficiency can be improved.

Description

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from Japanese patent application No. 2015-082589, filed on Apr. 14, 2015, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for processing a metal-cast article, and in particular to a method for processing a metal-cast article including a correcting step.

2. Description of Related Art

For example, in thin-walled metal-cast articles such as metal-cast articles formed by aluminum die casting, distortion tends to occur, for example, when they are taken out from casting apparatuses. In some cases, a metal-cast article undergoes a press-correction after a solution treatment or the like in order to remove such distortion.

In Japanese Unexamined Patent Application Publication No. 2004-322154, a metal-cast article undergoes a press-correction at a normal temperature after an aging process.

SUMMARY OF THE INVENTION

The inventors have found the following problem in the above method for processing a metal-cast article.

It is very difficult to accurately remove distortion by a correction at a normal temperature like the one disclosed in Japanese Unexamined Patent Application Publication No. 2004-322154. Further, a large load is required for the correction. Therefore, in some cases, a correction is performed with heating the metal-cast article again, for example, after the solution treatment or the like.

However, such heating for a correction needs to be separately performed from the solution treatment and the aging process. Therefore, there has been a problem that the above-described processing method in which a separate heating process is necessary has poor productivity and poor energy efficiency.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method for processing a metal-cast article capable of accurately removing distortion in a correcting process for the metal-cast article and thereby having excellent productivity and energy efficiency.

A first exemplary aspect of the present invention is

• • a method for processing a metal-cast article including a correcting step of starting to pressurize the metal-cast article by a press machine before a temperature of the metal-cast article decreases to 200° C. or lower after casting is finished.

In the method for processing a metal-cast article according to the aspect of the present invention, the correction is performed by starting the pressurization of the metal-cast article by the press machine before the temperature of the metal-cast article decreases to 200° C. or lower after the casting is finished. Therefore, the correction is performed at a relatively high temperature, thus making it possible to accurately remove distortion even when the load for the correction is small. Further, compared to the case where the correcting process is separately performed after the solution treatment, there is no need to heat the metal-cast article again for the correction. Therefore, the productivity and energy efficiency are excellent.

The method preferably further includes a trimming step of cooling the metal-cast article to a normal temperature while maintaining the pressurized state of the metal-cast article by the press machine, and shearing off an unnecessary part of the metal-cast article. The time required for the trimming of the metal-cast article can be reduced and hence the productivity can be further improved.

Further, the press machine preferably includes an upper mold and a lower mold with a refrigerant channel formed therein, and when the metal-cast article is cooled, a refrigerant is preferably made to flow through the refrigerant channel. The metal-cast article can efficiently be cooled while maintaining the metal-cast article in the pressurized state.

Further, when the metal-cast article is cooled, the temperature of the metal-cast article is preferably measured and the flow rate of the refrigerant is preferably adjusted based on the measured temperature. The metal-cast article can be uniformly cooled.

According to the present invention, it is possible to provide a method for processing a metal-cast article capable of accurately removing distortion in a correcting process for the metal-cast article and thereby having excellent productivity and energy efficiency.

The above and other objects, features and advantages of the present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing a method for processing a metal-cast article according to a first exemplary embodiment;

FIG. 2 is a flowchart showing a method for processing a metal-cast article according to a comparative example;

FIG. 3 is a schematic temperature chart showing a comparison between the method for processing a metal-cast article according to the first exemplary embodiment and that according to the comparative example;

FIG. 4 is a schematic cross section showing a correction apparatus for a metal-cast article according to the first exemplary embodiment;

FIG. 5 is a schematic cross section showing the correction apparatus for a metal-cast article according to the first exemplary embodiment;

FIG. 6 shows a plan view showing an arrangement example of coolant channels WC and thermocouples TC in an upper mold, and cross sections taken along respective cutting lines in the plan view;

FIG. 7 is a flowchart showing a method for controlling a cooling temperature for a metal-cast article;

FIG. 8 is a flowchart showing a method for processing a metal-cast article according to a second exemplary embodiment;

FIG. 9 is a schematic temperature chart showing a comparison between the method for processing a metal-cast article according to the first exemplary embodiment and that according to the second exemplary embodiment;

FIG. 10 is a schematic cross section showing a correction apparatus for a metal-cast article according to the second exemplary embodiment;

FIG. 11 is a schematic cross section showing the correction apparatus for a metal-cast article according to the second exemplary embodiment; and

FIG. 12 is a schematic cross section showing the correction apparatus for a metal-cast article according to the second exemplary embodiment.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Specific exemplary embodiments to which the present invention is applied are explained hereinafter in detail with reference to the drawings. However, the present invention is not limited to exemplary embodiments shown below. Further, the following descriptions and the drawings are simplified as appropriate for clarifying the explanation.

First Exemplary Embodiment

Firstly, a method for processing a metal-cast article according to a first exemplary embodiment of the present invention is explained with reference to FIG. 1. FIG. 1 is a flowchart showing a method for processing a metal-cast article according to the first exemplary embodiment. As an example, a metal-cast article formed by aluminum die casting is explained. As shown in FIG. 1, the method for processing the metal-cast article includes five steps consisting of steps ST11, ST12, ST13, ST14 and ST16. Note that the step ST12 (correcting step) is an essential step in the method for processing a metal-cast article according to this exemplary embodiment, and therefore it is illustrated by solid lines. The other steps are illustrated by broken lines.

Firstly, as shown in FIG. 1, a metal-cast article is cast (step ST11). In the case of aluminum die casting, the temperature of the molten metal is, for example, about 680° C.

Next, in a cooling process for the metal-cast article taken out from the casting apparatus, the metal-cast article starts to be pressurized by a press machine when the metal-cast article is at a somewhat high temperature (specifically, before the temperature of the metal-cast article decreases to 200° C. or lower) (step ST12). Note that if the temperature of the metal-cast article is lower than 200° C. when the pressurization is started, distortion cannot be accurately removed. In the correction, the higher the temperature of the metal-cast article is, the more accurately distortion can be removed. Further, the higher the temperature is, the more the necessary load for the correction can be reduced. Therefore, in the case of aluminum die casting, the pressurization is preferably started before the temperature of the metal-cast article decreases to 300° C. or lower. More preferably, the pressurization is started before the temperature decreases to 400° C. or lower. The temperature of the metal-cast article is, for example, about 500° C. when it is taken out from the casting apparatus.

Further, the metal-cast article is preferably cast while measuring the temperature of the metal-cast article so that cast metal-cast articles are cast under the same temperature condition as each other.

The press machine includes cooling means and cools the metal-cast article to, for example, 100° C. or lower while maintaining the pressurized state of the metal-cast article by the press machine. Details of the press machine are described later.

Next, an unnecessary part(s) of the metal-cast article taken out from the press machine is trimmed off by, for example, a shearing machine (step ST13). Note that examples of the unnecessary part include an overflow part caused by die casting and a casting plan part such as a biscuit/runner part. The lower the temperature, the higher the accuracy of the trimming becomes. Therefore, as described above, the trimming of the unnecessary part of the metal-cast article is preferably performed after the metal-cast article is cooled to 100° C. or lower by the press machine.

After that, a solution treatment is performed (step ST14). The solution treatment is a process for bringing alloy elements into a solid solution state in a matrix by rapidly cooling the metal-cast article after keeping the metal-cast article at a relatively high temperature for a predetermined time. In the case of aluminum die casting, the temperature of the solution treatment is, for example, about 500° C.

After that, an aging process is performed (step ST16). The aging process is a process for strengthening the alloy by keeping the metal-cast article at a temperature between a normal temperature and the solution treatment temperature for a predetermined time and thereby precipitating the solid-solution elements. In the case of aluminum die casting, the aging temperature is, for example, about 220 to 230° C.

Here, a method for processing a metal-cast article according to a comparative example is explained with reference to FIG. 2. FIG. 2 is a flowchart showing a method for processing a metal-cast article according to the comparative example.

Casting (step ST1), trimming (step ST3), a solution treatment (step ST4), and an aging process (step ST6) shown in FIG. 2 are similar to the above-described casting (step ST11), the trimming (step ST13), the solution treatment (step ST14), and the aging process (step ST16), respectively, shown in FIG. 1. Therefore, their detailed explanations are omitted.

In the comparative example, a metal-cast article taken out from a casting apparatus is put into a water tank and thereby water-cooled (step ST2), and an unnecessary part(s) of the metal-cast article taken out from the water tank is trimmed off (step ST3). Then, the metal-cast article is heated again and a press-correction is performed for the metal-cast article by a press machine after the solution treatment (step ST4) and before the aging process (step ST6).

FIG. 3 is a schematic temperature chart showing a comparison between the method for processing a metal-cast article according to the first exemplary embodiment and that according to the comparative example. As shown in the upper part of FIG. 3, in the correcting step for a metal-cast article according to the comparative example, it is necessary to heat the metal-cast article again just for the correction after the metal-cast article is rapidly cooled in the solution treatment. Further, the corrected metal-cast article is heated again for the aging process after being cooled.

In contrast to this, as shown in the lower part of FIG. 3, in the correcting step in the method for processing a metal-cast article according to this exemplary embodiment, the metal-cast article taken out from the casting apparatus is corrected when the metal-cast article is at a somewhat high temperature (specifically, before the temperature of the metal-cast article decreases to 200° C. or lower) in the cooling process of the metal-cast article. In the example shown in the figure, the metal-cast article is corrected when its temperature is about 500° C. Since the metal-cast article is corrected when the metal-cast article is at a somewhat high temperature as described above, distortion can be accurately removed. Further, since the metal-cast article is corrected in the cooling process of the metal-cast article, which is performed during the casting process, there is no need to heat the metal-cast article for the correction. As a result, the overall energy efficiency of the method for processing the metal-cast article is excellent. In addition, since the processing time can be reduced by an amount roughly equivalent to the time required for the correction in the comparative example, the productivity of the method for processing the metal-cast article as a whole is excellent.

Further, in the correcting step for the metal-cast article according to the comparative example, it is necessary to set the heating temperature to a temperature lower than the aging temperature. In the case of aluminum die casting, since the aging temperature is about 220 to 230° C., the heating temperature for the correction is, for example, about 200° C. In contrast to this, since the correcting step for the metal-cast article according to this exemplary embodiment is performed before the solution treatment, the temperature of the metal-cast article in the correcting step is not restricted by the aging temperature. That is, the temperature of the metal-cast article in the correcting step can be raised to a temperature higher than the aging temperature. Therefore, compared to the comparative example, distortion can be removed more accurately and the load required for the correction can be reduced.

Further, in view of the manufacturing equipment, the use of the method for processing a metal-cast article according to this exemplary embodiment can eliminate the need for the water tank for the water-cooling, which is necessary in the comparative example, thus making it possible to reduce the necessary space for the manufacturing equipment.

Next, a configuration and an operation of a correction apparatus for a metal-cast article according to this exemplary embodiment are explained with reference to FIGS. 4 and 5. FIGS. 4 and 5 are schematic cross sections showing a correction apparatus for a metal-cast article according to the first exemplary embodiment. FIG. 4 shows a state in the correction apparatus before a metal-cast article 40 is pressurized. FIG. 5 shows a state in the correction apparatus where the metal-cast article 40 is being pressurized. Note that the right-handed xyz-coordinate systems shown in FIGS. 4 and 5 and other figures, which are consistent with each other in these figures, are shown just for the sake of convenience for explaining the positional relation among components. Typically, the xy-plane forms a horizontal plane and the positive direction on the z-axis is the vertically upward direction.

Firstly, the configuration of the correction apparatus for a metal-cast article according to this exemplary embodiment is explained with reference to FIGS. 4 and 5. The correction apparatus according to the first exemplary embodiment is a press machine including an upper mold 10 and a lower mold 20 that are disposed to be opposed to each other. For example, the upper mold 10 is a movable mold and the lower mold 20 is a fixed mold. Projections and depressions corresponding to the shape of the metal-cast article 40 are formed on the opposed surfaces of the upper and lower molds 10 and 20. The upper mold 10 can be vertically moved by a servo-motor (not shown) through a piston rod 11. As the upper mold 10 is lowered, the metal-cast article 40 is pressurized and thereby corrected by the upper and lower molds 10 and 20. The piston rod 11 is equipped with a load cell 12 for measuring the load applied on the metal-cast article 40. The load cell 12 makes it possible to apply an optimal load to the metal-cast article 40 for achieving predetermined dimensional accuracy.

In the correction apparatus for a metal-cast article according to this exemplary embodiment, coolant channels (refrigerant channels) WC are formed inside of each of the upper and lower molds 10 and 20. In this way, as shown in FIG. 5, the metal-cast article 40 can be efficiently cooled in the state where the metal-cast article 40 is pressurized. In the example shown in the figures, a plurality of coolant channels WC each having a U-shape in cross section are formed in each of the upper and lower molds 10 and 20. As described above, the correction apparatus has a configuration in which a plurality of coolant channels WCs are separately provided in each of the upper and lower molds 10 and 20 and the amounts of the coolants for these coolant channels WC can be independently controlled.

Further, as shown in FIG. 4, a temperature in an area near the metal-cast article 40 inside of each of the upper and lower molds 10 and 20 can be measured by a thermocouple TC. That is, the temperature of the metal-cast article 40 can be indirectly measured. Therefore, it is possible to uniformly cool the whole metal-cast article 40 by adjusting the amount of the coolant for each of the coolant channels WC in each of the upper and lower molds 10 and 20 while measuring the temperature of the metal-cast article 40. Further, since the correction can be started at the same temperature for every metal-cast article 40 by measuring the temperature of the metal-cast article 40 by the thermocouple TC, variations among products can be reduced. Note that arrangement examples of the coolant channels WC are described later.

Next, the operation of the correction apparatus for a metal-cast article according to this exemplary embodiment is explained with reference to FIGS. 4 and 5. When the temperature of the metal-cast article 40 placed in the correction apparatus reaches a predetermined temperature in the cooling process, the upper mold 10 is lowered as shown in FIG. 4. As a result, the metal-cast article 40 is sandwiched between the upper and lower molds 10 and 20 and thereby corrected as shown in FIG. 5. As shown in the temperature chart in the lower part of FIG. 3, the metal-cast article 40 is pressurized without making any coolant flow inside the upper and lower molds 10 and 20 for a predetermined period after the pressurization is started. That is, while maintaining the metal-cast article 40 at a high temperature, the load on the metal-cast article 40 is continuously or repeatedly measured by the load cell 12 so that the metal-cast article 40 is corrected by a predetermined optimal load.

After that, as shown in FIG. 5, the metal-cast article 40 is cooled by making coolants flow through the coolant channels WC formed inside the upper and lower molds 10 and 20 while maintaining the metal-cast article 40 in the pressurized state. As described above, the amount of the coolant for each of the coolant channels WC in each of the upper and lower molds 10 and 20 is adjusted while measuring the temperature of the metal-cast article 40 by the thermocouple TC. In this way, the whole metal-cast article 40 is uniformly cooled and hence thermal distortion can be prevented or reduced.

Through the above-described operation of the correction apparatus, a press-correction can be performed for the metal-cast article 40 taken out from the casting apparatus, whose temperature has reached the predetermined temperature, in the cooling process of the metal-cast article 40.

Next, a method for controlling the cooling temperature for the metal-cast article 40 is explained with reference to FIGS. 6 and 7. FIG. 6 shows a plan view showing an arrangement example of coolant channels WC and thermocouples TC in the upper mold 10, and cross sections taken along respective cutting lines in the plan view. FIG. 7 is a flowchart showing a method for controlling a cooling temperature for a metal-cast article. Note that in the plan view in FIG. 6, the thermocouples TC are indicated by hatching so that the coolant channels WC and the thermocouples TC can be easily distinguished from each other.

Firstly, an arrangement example of coolant channels WC and thermocouples TC in the upper mold 10 is explained with reference to FIG. 6.

As shown in the plan view in FIG. 6, five mutually-independent pairs of coolant channels WC, i.e., ten coolant channels WC in total are formed in the upper mold 10. As shown in the lowermost cross section and the second cross section from the bottom in FIG. 6, each of the coolant channels WC is formed in a U-shape in cross section so that a coolant flows into the coolant channel WC from the top surface of the upper mold 10, passes through an area near the bottom surface of the upper mold 10, and flows out from the coolant channel WC from the top surface of the upper mold 10.

As shown in the plan view in FIG. 6, two coolant channels WC each having a U-shape in cross section as described above are disposed to be opposed to each other with one thermocouple TC disposed therebetween. Further, in total, five sets each of which consists of two coolant channels WC and one thermocouple TC as described above are arranged in the four corners and the center of the upper mold 10. Since the center of the metal-cast article 40 is less likely to be cooled, the two coolant channels WC disposed at the center of the upper mold 10 are thicker (i.e., larger in diameter) than the other eight coolant channels. With the above-described configuration, the whole metal-cast article 40 can be uniformly cooled.

As shown in the uppermost cross section and the second cross section from the top in FIG. 6, each of the thermocouples TC is inserted from the top surface of the upper mold 10 to an area near the bottom surface thereof in order to measure the temperature of the metal-cast article 40. By continuously or repeatedly measuring the temperature of the metal-cast article 40 by each of the thermocouples TC, it is possible to adjust the flow rates of the coolants made to flow through the two coolant channels WC disposed on the periphery of that thermocouple TC according to the measured temperature of the metal-cast article 40. As described above, the flow rates for the five pairs of coolant channels WC corresponding to the five thermocouples TC can be adjusted independently of each other. With the above-described configuration, the cooling temperature in each part of the metal-cast article 40 can be controlled. As a result, the whole metal-cast article 40 can be uniformly cooled.

Note that the coolant channels WC and the thermocouples TC in the lower mold 20 are similar to those in the upper mold 10, and therefore their explanations are omitted. Further, needless to say, the arrangement example of the coolant channels WC and the thermocouples TC shown in FIG. 6 is merely an example. That is, the arrangement of coolant channels WC and thermocouples TC is not limited to the above-described arrangement.

Next, a method for controlling the cooling temperature for the metal-cast article 40 is explained with reference to FIG. 7.

As shown in FIG. 7, upon starting to cool the metal-cast article 40 by starting to make a coolant flow to the upper and lower molds 10 and 20, the temperature of the metal-cast article 40 at a time t is measured by the thermocouple TC (step ST51). Note that the time t means a time elapsed from the start of the cooling.

Next, it is determined whether or not the measured temperature of the metal-cast article 40 at the time t is within a target temperature range (step ST52). Note that the target temperature and its tolerance range for the metal-cast article 40 at the time t are determined in advance by preliminary tests or the like. When the temperature of the metal-cast article 40 is within the target temperature range (Yes at step ST52), the process returns to the step ST51 without changing the amount of the coolant.

On the other hand, when the temperature of the metal-cast article 40 is not within the target temperature range (No at step ST52), the process returns to the step ST51 after changing the amount of the coolant (step ST53). Specifically, when the temperature of the metal-cast article 40 is higher than the target temperature range, the amount of the coolant is increased, whereas when the temperature of the metal-cast article 40 is lower than the target temperature range, the amount of the coolant is reduced. The above-described control is performed for each pair of two coolant channels WC disposed on the periphery of its corresponding thermocouple TC. Consequently, the whole metal-cast article 40 can be uniformly cooled.

As explained above, in the method for processing a metal-cast article according to this exemplary embodiment, the metal-cast article is corrected before the temperature of the metal-cast article decreases to 200° C. or lower after the casting is finished. Since the metal-cast article is corrected in the cooling process of the metal-cast article for the casting process, there is no need to heat the metal-cast article for the correction. As a result, the overall energy efficiency and productivity of the method for processing the metal-cast article is excellent. Further, since the metal-cast article is corrected before the temperature of the metal-cast article decreases to 200° C. or lower, distortion can be accurately removed. That is, the method for processing a metal-cast article according to this exemplary embodiment makes it possible to accurately remove distortion and has excellent productivity and energy efficiency.

Second Exemplary Embodiment

Next, a method for processing a metal-cast article according to a second exemplary embodiment of the present invention is explained with reference to FIG. 8. FIG. 8 is a flowchart showing a method for processing a metal-cast article according to the second exemplary embodiment.

In the first exemplary embodiment, as shown in FIG. 1, after the press-correction is performed for the metal-cast article taken out from the casting apparatus, whose temperature has reached the predetermined temperature, by using the press machine in the cooling process of the metal-cast (step ST12), an unnecessary part(s) of the metal-cast article taken out form the casting apparatus is trimmed off by, for example, a shearing machine (step ST13). In contrast to this, in the second exemplary embodiment, as shown in FIG. 8, after the press-correction is performed for the metal-cast article taken out from the casting apparatus, whose temperature has reached the predetermined temperature, by using the press machine in the cooling process of the metal-cast, the metal-cast article is cooled while maintaining the pressurized state of the metal-cast article by the press machine and an unnecessary part(s) of the metal-cast article that sticks out from the press machine is trimmed off by a shearing machine (step ST22). This step ST22 corresponds to a method for processing a metal-cast article according to this exemplary embodiment and includes a correcting step and a trimming process for the metal-cast article. The other configuration is similar to that of the first exemplary embodiment and therefore its explanation is omitted.

FIG. 9 is a schematic temperature chart showing a comparison between the method for processing a metal-cast article according to the first exemplary embodiment and that according to the second exemplary embodiment. As shown in the upper part of FIG. 9, the processing method according to the first exemplary embodiment requires a time because after the metal-cast article is taken out from the press machine for the correction, the metal-cast article is moved to a shearing machine or the like to perform trimming for the metal-cast article.

In contrast to this, as shown in the lower part of FIG. 9, in the method for processing a metal-cast article according to this exemplary embodiment, the metal-cast article is cooled while maintaining the pressurized state of the metal-cast article by the press machine and an unnecessary part(s) of the metal-cast article that sticks out from the press machine is trimmed off by a shearing machine. That is, the correction apparatus for a metal-cast article according to this exemplary embodiment includes a shearing machine as well as the press machine and hence can perform trimming as well as the correction. Details of the correction apparatus according to this exemplary embodiment are described later. Therefore, this exemplary embodiment can reduce the time required for the trimming in the first exemplary embodiment and hence improve the overall productivity of the method for processing the metal-cast article even further. Further, in view of the manufacturing equipment, the use of the method for processing a metal-cast article according to this exemplary embodiment can eliminate the need for the separate shearing machine, which is necessary in the first exemplary embodiment, thus making it possible to reduce the necessary space for the manufacturing equipment.

Next, a configuration and an operation of a correction apparatus for a metal-cast article according to this exemplary embodiment are explained with reference to FIGS. 10 to 12. FIGS. 10 to 12 are schematic cross sections showing a correction apparatus for a metal-cast article according to the second exemplary embodiment. FIG. 10 shows a state in the correction apparatus before a metal-cast article 40 is pressurized. FIG. 11 shows a state in the correction apparatus where the metal-cast article 40 is being pressurized. FIG. 12 shows a state in the correction apparatus where unnecessary parts such as an overflow part 40a and a biscuit/runner part 40b are sheared off.

Firstly, the configuration of the correction apparatus for a metal-cast article according to this exemplary embodiment is explained with reference to FIGS. 10 to 12. The correction apparatus according to the second exemplary embodiment includes a shearing mold 30 in addition to the press machine including the upper mold 10 and the lower mold 20 that are disposed to be opposed to each other. In the second exemplary embodiment, in addition to the upper mold 10, which can be vertically moved, the lower mold 20 can also be vertically moved by a servo-motor (not shown) through a piston rod 21.

When the metal-cast article 40 is corrected, the upper mold 10 is lowered so that the metal-cast article 40 is pressurized and thereby corrected by the upper and lower molds 10 and 20. Further, when shearing is performed, the upper and lower molds 10 and 20 are lowered in a synchronized manner while maintaining the pressurized state of the metal-cast article 40 by the upper and lower molds 10 and 20. In this way, unnecessary parts (the overflow part 40a and the biscuit/runner part 40b) of the metal-cast article 40, which stick out from the upper and lower molds 10 and 20, are trimmed off by the fixed shearing mold 30.

Alternatively, the correction apparatus may be configured so that, instead of lowering the upper and lower molds 10 and 20, the shearing mold 30 is lifted to shear off unnecessary parts (the overflow part 40a and the biscuit/runner part 40b).

Next, the operation of the correction apparatus for a metal-cast article according to this exemplary embodiment is explained with reference to FIGS. 10 to 12. When the temperature of the metal-cast article 40 placed in the correction apparatus reaches a predetermined temperature in the cooling process, the upper mold 10 is lowered as shown in FIG. 10. As a result, the metal-cast article 40 is sandwiched between the upper and lower molds 10 and 20 and thereby corrected as shown in FIG. 11. As shown in the temperature chart in the lower part of FIG. 9, the metal-cast article 40 is pressurized without making any coolant flow inside the upper and lower molds 10 and 20 for a predetermined period after the pressurization is started. That is, similarly to the first exemplary embodiment, while maintaining the metal-cast article 40 at a high temperature, the load on the metal-cast article 40 is continuously or repeatedly measured by the load cell 12 so that the metal-cast article 40 is corrected by a predetermined optimal load.

After that, as shown in FIG. 11, the metal-cast article 40 is cooled by making coolants flow through the coolant channels WC formed inside the upper and lower molds 10 and 20 while maintaining the metal-cast article 40 in the pressurized state. Similarly to the first exemplary embodiment, the amount of the coolant for each of the coolant channels WC in each of the upper and lower molds 10 and 20 is adjusted while measuring the temperature of the metal-cast article 40 by the thermocouple TC. In this way, the whole metal-cast article 40 is uniformly cooled and hence thermal distortion can be prevented or reduced.

Next, as shown in FIG. 12, the upper and lower molds 10 and 20 are lowered in a synchronized manner while maintaining the pressurized state of the metal-cast article 40, and unnecessary parts (the overflow part 40a and the biscuit/runner part 40b) of the metal-cast article 40 are thereby trimmed off by the fixed shearing mold 30.

Through the above-described operation of the correction apparatus, in the cooling process of the metal-cast article 40 taken out from the casting apparatus, after the press-correction is performed for the metal-cast article 40, whose temperature has reached the predetermined temperature, the metal-cast article 40 is further cooled and unnecessary parts can be trimmed off.

Note that the present invention is not limited to the above-described first exemplary embodiment, and it can be modified as appropriate without departing from the sprit and scope of the present invention.

For example, the target metal-cast articles are not limited to the die-cast articles. That is, they may be metal-cast articles formed by gravity casting, low-pressure casting, or other casting methods.

Further, the type of molten metal is not limited to aluminum. That is, the molten metal may be magnesium, iron, other metals, or alloys.

Further, the refrigerant is not limited to coolants and other types of refrigerants may be used.

The cooling means for a metal-cast article may have a configuration in which air or other cooling gases are blown on the metal-cast article.

From the invention thus described, it will be obvious that the embodiments of the invention may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.

Claims

1. A method for processing a metal-cast article comprising a correcting step of starting to pressurize the metal-cast article by a press machine before a temperature of the metal-cast article decreases to 200° C. or lower after casting is finished.

2. The method for processing a metal-cast article according to claim 1, further comprising a trimming step of cooling the metal-cast article to a normal temperature while maintaining the pressurized state of the metal-cast article by the press machine, and shearing off an unnecessary part of the metal-cast article.

3. The method for processing a metal-cast article according to claim 2, wherein

the press machine comprises an upper mold and a lower mold with a refrigerant channel formed therein, and

when the metal-cast article is cooled, a refrigerant is made to flow through the refrigerant channel.

4. The method for processing a metal-cast article according to claim 3, wherein when the metal-cast article is cooled,

the temperature of the metal-cast article is measured, and

a flow rate of the refrigerant is adjusted based on the measured temperature.