JP2008055473A - Method and apparatus for manufacturing aluminum die-cast product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing an aluminum die-cast product with which the aluminum die-cast product having no cast defect and being sound and high quality can be manufactured by eliminating the development of shrinkage cavity or reducing it to the extremely small volume. <P>SOLUTION: In the method for manufacturing the aluminum die-cast product, with which the molten metal 12 filled in a die 11 under pressure is subjected to the die-casting by pressurizing a portion easily developing the cast defect through the solidification and the shrinkage in the solidifying process with a locally pressurizing pin 16, the locally pressurizing pin 16 is made to follow based on the shifting of the interface of the solidification obtained with a precalculated solidified interface shifting speed of the molten metal and continued to push in till the time point of the completing of solidification. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for manufacturing an aluminum die-cast product suitable for use in manufacturing a pressure vessel or the like that requires airtightness.

In general, it is known that in an aluminum die-cast product, a solidification shrinkage space accompanying solidification shrinkage is generated around a portion where the solidification rate of a molten metal filled in a mold is the slowest during die casting. In the case of an aluminum alloy, a volume shrinkage of about 6% occurs during solidification. When the shrinkage space is contained in the product, a concentrated shrinkage cavity is generated, which becomes a casting defect. The shrinkage nest has a tendency to spread over a wider range as the thickness of the cast part is thicker and the mold temperature is higher (temperature gradient is smaller).
The shrinkage cavity, which is the casting defect described above, is one of the major factors that cause a pressure leak when the product is a pressure vessel and cause a decrease in the yield of the product.

As a technique for reducing the generation of shrinkage cavities during casting, a local pressurization method is known in which a portion where shrinkage cavities are likely to occur is partially pressurized in a semi-solid state immediately before the filled molten metal solidifies (for example, Patent Documents 1 and 2).
In the one disclosed in Patent Document 2, the measurement squeeze pressure falls within a predetermined range of the set squeeze pressure while detecting the pressure of the local pressurization pin by pressing the local pressurization pin immediately before solidification by a hydraulic cylinder. By operating the hydraulic cylinder to the maximum and controlling the stroke value of the local pressure pin, the shrinkage nest is reduced or eliminated.

JP 59-156560 A JP-A-8-155622

However, in the above-mentioned Patent Document 2, the local pressure pin is simply pushed in while detecting the pressure at the time set by the timer, and the solidification speed and solidification timing of the molten metal filled in the mold are accurately determined. Therefore, it cannot be said that the local pressure pin is controlled.
In order to reliably close the coagulation / shrinkage space that is opening with the coagulation / shrinkage, it is necessary to control the pressurization of the local pressurization pin in accordance with the coagulation timing. Accurately grasping the local pressure pin control is not performed, the success probability of coagulation contraction space closing is low, and the shrinkage nest has not been resolved.
From the above, the die-cast pressure vessel is in a situation where the yield for the pressure leakage caused by the shrinkage nest is not reached.

  The present invention has been made in view of such circumstances, and by controlling the pushing operation of the local pressure pin, the occurrence of shrinkage nests can be eliminated or reduced to a very small amount, and there is no casting defect. An object of the present invention is to provide a method and an apparatus for producing an aluminum die-cast product, which can produce a high-quality aluminum die-cast product.

In order to solve the above problems, the method and apparatus for producing an aluminum die-cast product of the present invention employs the following means.
That is, in the method for producing an aluminum die-cast product according to the present invention, the molten metal that has been pressure-filled in the mold is subjected to die-casting by pressurizing a portion where a casting defect is likely to occur due to solidification and shrinkage during the solidification process with a local pressure pin. In the method for producing an aluminum die cast product to be cast, the local pressure pin is made to follow based on the movement of the solidification interface obtained by the solidification interface movement speed of the molten metal calculated in advance, and continues to be pushed in until solidification is completed. And

  According to the present invention, the local pressurizing pin is connected to the calculated solidification interface movement speed of the melt [depth from the mold surface to the most solidified delay portion (mm) / solidification completion time of the most solidified delay portion (s). ] Is followed based on the movement of the solidification interface obtained by the above and is continuously pushed in until the solidification is completed, so that the local pressure pin can be pushed in according to the solidification timing of the molten metal. That is, by accurately grasping in advance the solidification interface moving speed of the portion requiring local pressurization in advance, and following the movement of the solidification interface obtained thereby, the local pressurization pin is continuously pushed in until the solidification completion point, The coagulation contraction space (which becomes a shrinkage nest) can be reliably closed. Therefore, the generation of shrinkage cavities accompanying solidification shrinkage can be eliminated or reduced to a very small amount, and a healthy aluminum die-cast product free from casting defects can be manufactured. In addition, this makes it possible to greatly improve the yield at the time of die casting and to manufacture a high quality aluminum die cast product at a low cost.

  Furthermore, the manufacturing method of the aluminum die-cast product of the present invention is the above-described manufacturing method of the aluminum die-cast product, wherein the pressurization by the local pressure pin is started 0.4 to 1.4 seconds after the filling of the molten metal is completed. It is characterized by doing.

According to the present invention, since the pressurization with the local pressurization pin starts 0.4 to 1.4 seconds after the completion of the filling of the molten metal, the solidification is surely completed by following the movement of the solidification interface. You can keep pushing to the point. In other words, if the pressurization start with the local pressurization pin is too early, the push-in resistance due to the molten metal is small before the start of solidification, so the push-in speed becomes too high, and the local pressurization pin is pushed into the stroke end, and the solidification is completed It becomes difficult to keep pushing the local pressurizing pin until. Therefore, by starting pressurization with the local pressurization pin within about 1 second immediately after the filling of the molten metal is completed and solidification is started (after 0.4 second from the completion of the filling), the local pressurization pin becomes The local pressure pin can be reliably pushed in until the solidification is completed without being pushed into the stroke end. Thereby, generation | occurrence | production of a shrinkage nest can be eliminated or reduced to a very small amount. In addition, when 1.4 seconds have elapsed from the completion of filling, the solidification of the pressed portion of the local pressure pin proceeds, and it becomes difficult to continue pushing the local pressure pin until the solidification completion time.
The solidification start of the molten metal is almost the same regardless of the size and shape of the die cast product, so the press start time by the local pressure pin is as described above regardless of the type of the aluminum die cast product. Can be set.

  Furthermore, the aluminum die-cast product manufacturing method of the present invention is the above-described aluminum die-cast product manufacturing method, wherein the average pressing speed V of the local pressure pin is 1.2 mm / s <V <2.63 mm / It is set as s.

  According to the present invention, since the average pressing speed V of the local pressure pin is set to 1.2 mm / s <V <2.63 mm / s, the local pressure pin is allowed to follow the movement of the solidification interface and solidify reliably. Pushing can be continued until completion, and pushing can be reliably pushed to a position where the shrinkage can be sufficiently crushed. Here, if the thickness of the part to be locally pressurized is about 20 mm, the solidification completion time of the most solidified delayed part is 3.8 seconds, so the solidification interface moving speed is 2.63 mm / s, and this is pushed into the upper limit. By pushing the local pressure pin as a speed, the local pressure pin can be surely pushed to a position where the shrinkage can be sufficiently crushed. When the indentation speed is 1.2 mm / s or less, the indentation resistance becomes excessive, and the local pressurizing pin cannot be pushed in. Also, the shallower the press-in depth of the local pressure pin, the more likely it will be that the shrinkage will be crushed. Therefore, control the press-in speed of the local pressure pin to ensure a sufficient push-in depth. Is an important factor in reliably closing the coagulation contraction space (which becomes a shrinkage nest). In other words, since there is a solidification time difference between the part where the solidification is completed (the mold contact part) and the part where the solidification is delayed most after the completion of the filling of the molten metal, even if the local pressure pin is pushed in instantaneously during this time, the effect is Rather, it is an important factor for surely eliminating or reducing the occurrence of shrinkage nests by pushing in to a sufficient depth over several seconds by the above-described pushing speed.

  Furthermore, the method for producing an aluminum die-cast product of the present invention is characterized in that, in any of the methods for producing an aluminum die-cast product described above, the aluminum die-cast product is a pressure vessel.

  According to the present invention, since the aluminum die-cast product is a pressure vessel, a pressure vessel having no casting defect (shrinkage cavity) that causes a pressure leak can be manufactured by die casting. Therefore, the yield against pressure leakage during die casting can be greatly improved, and a high-quality pressure vessel can be manufactured at low cost.

  Furthermore, the method for manufacturing an aluminum die-cast product according to the present invention is characterized in that, in the method for manufacturing an aluminum die-cast product, the pressure vessel is a housing of a compressor.

  According to the present invention, since the pressure vessel is a compressor housing, a highly airtight housing in which the refrigerant gas sealed inside does not leak by eliminating or reducing the occurrence of shrinkage cavities to a very small amount. Can be manufactured. In particular, in the case of a compressor housing, the thick boss portion of the housing is often cut after casting, and even if the outer surface is clean, if there is a shrinkage cavity that is a casting defect inside, it will be cut. Exposed on the surface causes leakage of refrigerant gas. According to the present invention, the generation of shrinkage cavities can be eliminated or reduced to a very small amount, so that it is possible to provide an optimum die casting method for a compressor housing.

  Furthermore, the apparatus for producing an aluminum die-cast product according to the present invention uses a local pressure pin to press a part that is likely to cause a casting defect due to solidification and shrinkage of the molten metal that has been pressure-filled in the mold during the solidification process. In an apparatus for producing an aluminum die-cast product to be cast, a local pressure pin that is provided corresponding to a portion where the casting defect is likely to occur and locally pressurizes the portion, and a push for pushing the local pressure pin toward the portion And a controller that controls the pushing means, and causes the local pressurizing pin to follow the movement of the solidification interface obtained by the solidification interface movement speed of the melt calculated in advance, and continues to push until the solidification completion time point, It is provided with.

  According to the present invention, the pushing means for pushing the local pressure pin is controlled, and the local pressure pin is made to follow based on the movement of the solidification interface obtained by the solidification interface movement speed of the molten metal calculated in advance. Since the control part which continues pushing in until completion is provided, this control part can push in a local pressurization pin according to the solidification timing of a molten metal. That is, the solidification interface moving speed of the portion requiring local pressurization can be accurately grasped beforehand by analysis, and the local pressurization pin can be continuously pushed in until the solidification completion time by following the movement of the solidification interface obtained thereby. Therefore, it is possible to reliably close the coagulation contraction space serving as the shrinkage nest. Therefore, the generation of shrinkage cavities due to solidification shrinkage can be eliminated or reduced to a very small amount, and a healthy die-cast product free from casting defects can be manufactured, and the yield during die casting can be greatly improved, Quality die casting products can be manufactured at low cost.

  Furthermore, an apparatus for manufacturing an aluminum die-cast product according to the present invention is the above-described apparatus for manufacturing an aluminum die-cast product, wherein an overflow portion is provided in the mold corresponding to a portion where the casting defect is likely to occur, and the local portion is added to the overflow portion. A pressure pin is attached so that it can be pushed in, and the overflow portion is locally pressurized by the local pressure pin.

  According to the present invention, an overflow part is provided in the mold, and a local pressurizing pin is attached to the overflow part so as to pressurize the overflow part locally. Indentation can be prevented from occurring. Therefore, it is possible to eliminate the restriction on the part to be locally pressurized and to manufacture a higher quality die-cast product having no pressure mark.

  According to the method and apparatus for producing an aluminum die-cast product of the present invention, it is possible to follow the movement of the solidification interface of the molten metal filled in the mold and continue to push the local pressure pin until the completion of solidification, resulting in a shrinkage nest. The coagulation contraction space can be closed reliably. Therefore, the generation of shrinkage cavities accompanying solidification shrinkage can be eliminated or reduced to a very small amount, and a healthy aluminum die-cast product free from casting defects can be manufactured. In addition, the yield during die casting can be greatly improved, and high-quality aluminum die-cast products can be manufactured at low cost.

In the following, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an example of an aluminum die-cast product manufactured by an aluminum die-cast product manufacturing method and apparatus according to this embodiment. Here, the housing 1 used for a compressor is illustrated as an aluminum die-cast product.
The housing 1 is made of an aluminum alloy ADC12 (JIS). A compression mechanism is incorporated inside the housing 1, and the refrigerant gas sealed in the refrigeration cycle is sucked into the housing 1, compressed and discharged from the housing 1, and is used as a pressure vessel. The

  The housing 1 has a cup shape having a thin cylindrical portion 1A, and a boss portion 1B having a thickness several times thicker than the cylindrical portion 1A is integrally die-cast at a plurality of locations on the outer periphery thereof. Yes. The boss 1B has a maximum wall thickness of 20 mm. The boss part 1B is a part in which screw holes, through holes and the like are cut after die casting, and if there is a solidification shrinkage space (which becomes a shrinkage nest) accompanying solidification shrinkage during die casting, cutting is performed. This exposes it to the cutting surface. Since this causes a refrigerant gas leak, it is inevitable to eliminate the occurrence of shrinkage cavities during die casting in order to obtain the housing 1 free from pressure leaks and gas leaks.

FIG. 2 shows a part of a die-cast manufacturing apparatus 10 for manufacturing an aluminum die-cast housing 1 in which a shrinkage cavity that is a casting defect does not occur.
The mold 11 is clamped by a clamping device (not shown), and the cavity 11A is evacuated by a vacuum pump immediately after clamping. In the mold 11, the surface temperature of the cavity 11 </ b> A is adjusted to 250 ° C. ± 50 ° C. under general aluminum die casting conditions. The cavity 11A of the mold 11 is filled with the molten metal 12 via a gate, a plunger, etc. (not shown). The molten metal temperature is 680 ° C. ± 50 ° C. under general aluminum die casting conditions. The injection of the molten metal 12 is generally performed by a two-stage motion of the plunger. First, the rod pressure and the head pressure are set constant in the low speed range, the plunger is moved slowly, and the high speed switching is performed when the molten metal 12 passes through the gate. In the high speed region, the plunger is accelerated rapidly, and the filling of the molten metal 12 into the cavity 11A is completed in about 0.1 seconds. This high injection speed is generally 1.0 m / s or more.

  The mold 11 is provided with an overflow portion 11B connected to the cavity 11A. The overflow portion 11B is provided corresponding to a portion where a shrinkage cavity that is a casting defect is likely to occur during casting. That is, in the housing 1, a plurality of locations (only one location is shown in FIG. 2) corresponding to the boss portion 1B (thickness 20 mm) thicker than the cylindrical portion 1A. Will be provided. And the local pressurization apparatus 13 which can pressurize the molten metal 12 with which the said overflow part 11B was filled separately is attached to the exterior side of the metal mold | die 11. FIG.

  The local pressure device 13 includes a pressure cylinder 14 attached to the mold 11 and a local pressure pin 16 connected to a piston 15 of the pressure cylinder 14 and stroked for a predetermined range. The local pressurizing pin 16 is installed so as to be pushed into the overflow part 11B. In this embodiment, the maximum pushing stroke L is set to 18 mm, for example, and the pin diameter is set to 9 mm, for example.

  The pressure cylinder 14 is used to push the local pressure pin 16 into the overflow portion 11B. The pressure cylinder 14 is supplied with oil from one hydraulic supply source (not shown) via a direction switching valve 17, a solenoid valve 18, and a throttle valve 19 to the pressure cylinder 14 and from the other chamber 14B. As is well known, hydraulic circuits 20A and 20B are connected so that the oil is discharged through 17. The hydraulic circuit 20B is provided with a flow meter 21 for monitoring the stroke of the local pressurizing pin 16.

Further, the direction switching valve 17, the electromagnetic valve 18, the throttle valve 19 and the flow meter 21 provided in the hydraulic circuits 20 </ b> A and 20 </ b> B of the pressurizing cylinder 14 are controlled and monitored by the control device 22. .
Since the control device 22 pushes the local pressure pin 16 into the overflow portion 11B in accordance with the solidification timing of the molten metal 12 filled in the cavity 11A of the mold 11, the following two points are used as parameters for the local pressure pin 16: The movement can be controlled.
(1) The start time ts of the local pressurizing pin 16 is determined by setting a timer for opening and closing the electromagnetic valve 18.
(2) The pushing speed V of the local pressurizing pin 16 is controlled by changing the opening of the throttle valve 19 and adjusting the flow rate of the pressurized oil.

In order to eliminate the occurrence of the shrinkage defect by surely closing the solidification shrinkage space by locally pressurizing the portion where the shrinkage defect that is a casting defect is likely to occur by the local pressurization device 13 described above, It is necessary that the generation position is at a position where it can be crushed by pressing the local pressure pin 16 and that the movement of the local pressure pin 16 is appropriately controlled in accordance with the solidification timing of the molten metal 12.
FIG. 3 shows a solidified closed loop formation state of the local pressurization portion predicted by the analysis.
Here, when the coagulation closed loop formation state in the local pressurization pin standby state was predicted, the coagulation closed loop was formed immediately below the local pressurization pin 16 installed at the thickest part (thickness 20 mm) where the formation of the coagulation closed loop was expected. It was determined that the defect could be closed if the local pressure pin 16 was appropriately controlled. In addition, there is a difference in solidification time of 3.6 seconds between the portion of the first solidification completed (the contact portion with the mold 11) and the portion of the latest solidification delay from the point of completion of the molten metal predicted in the analysis. It was estimated that even when the local pressure pin 16 was pushed in instantaneously, there was no effect, and it was necessary to push the local pressure pin 16 to a sufficient depth over several seconds. As shown in FIG. 3, in the case of the present embodiment, the molten metal 12 starts to solidify 0.2 seconds after the completion of filling, and the time until the solidification is completed is 3.8 seconds. .

By the above analysis, the solidification interface moving speed of the portion requiring local pressurization is accurately grasped in advance, and the local pressurization pin 16 is continuously pushed in until the solidification completion time by following the movement of the solidification interface obtained thereby. Thus, it was possible to obtain the knowledge that the coagulation contraction space (which becomes the shrinkage nest) can be closed reliably. The solidification interface moving speed of the molten metal 12 can be calculated by “depth from the mold surface to the most solidified delay portion (mm) / solidification completion time of the most solidified delay portion (s)”.
Based on this knowledge, a local pressure product was prototyped using two parameters, (1) the start time ts of the local pressure pin 16 and (2) the pressing speed V of the local pressure pin 16 as described above. A quality survey was conducted.

FIG. 4 shows a quality survey of the local pressure prototype. The X-ray evaluation results are plotted with the shape of the plot points (○, △, and □) indicating each experimental condition, the specific gravity is added with the pattern of the plot points (black, dots, and white), and the plot points are added. These numbers indicate the average pushing speed V of the local pressure pin 16.
As a result, an improvement was generally recognized as compared with the conventional cast pin method (the die pin is formed by partially press-inserting the cast pin into the boss 1B during die casting). However, the smaller the depth of pressing of the local pressurizing pin 16 is, the less the defect is crushed. In addition, as the start time of the local pressure pin 16 is faster and the push-in speed V is larger, the local pressure pin 16 tends to be pushed to the stroke end. There is. Therefore, it is considered desirable to avoid these conditions in order to obtain stable quality during mass production.
Moreover, although the specific gravity by the conventional cast pin construction method was about 2.67 g / cm ³ , all of the prototypes were 2.71 g / cm ³ or more, and an improvement was recognized.

In particular, within the range of the thick solid line in FIG. 4, it was confirmed that no defects were found in the X-ray evaluation, and high quality with a specific gravity of 2.73 g / cm ³ or more was obtained.
That is, the starting time of the local pressurizing pin 16 is 0.4 to 1.4 seconds after the filling of the molten metal 12 is completed. That is, the pressurization by the local pressurizing pin 16 is started 0.4 to 1.4 seconds after the completion of the filling of the molten metal 12, and when the solidification of the molten metal 12 is completed (here, 3.8 seconds from the completion of the filling). It is desirable to keep pushing the local pressure pin 16 until it reaches. If the pressurization starts too early, the indentation resistance by the molten metal 12 is small before the start of solidification, the indentation speed becomes too large, and the local pressurization pin 16 is pushed in to the stroke end, so that the local addition is completed until the solidification is completed. It becomes difficult to keep pressing the pressure pin 16. On the other hand, if the start of pressurization by the local pressurization pin 16 is too late, solidification has progressed, so that the depth of indentation of the local pressurization pin 16 becomes shallow, and there is a possibility that the method of crushing defects becomes insufficient. By starting the pressurization by the local pressurization pin 16 for about 1 second immediately after the filling of the molten metal 12 is completed and solidification is started (0.4 seconds after the completion of the filling), the local pressurization pin 16 is started. Is not pushed to the stroke end, and the local pressure pin can be surely kept pushed until the solidification is completed, and the local pressure pin 16 can be pushed to a sufficient depth.

In addition, it is desirable that the average pushing speed V of the local pressurizing pin 16 is in a range of 1.2 mm / s <V <2.63 mm / s. In other words, by setting the average pressing speed V of the local pressure pin 16 to 1.2 mm / s <V <2.63 mm / s, the local pressure pin 16 can be made to follow the movement of the solidification interface of the molten metal 12 and reliably. In this way, it can be surely pushed to the position where the shrinkage can be sufficiently crushed while continuing to push until the solidification is completed.
Here, when the thickness of the boss 1B to be locally pressurized is 20 mm, the solidification completion time of the most solidified delay portion is 3.8 seconds (see FIG. 3). Accordingly, the solidification interface moving speed is from 10 mm / 3.8 s to 2.63 mm / s, and this is used as the upper limit pushing speed V, and the local pressurizing pin 16 is pushed into the position where the shrinkage nest can be sufficiently crushed. The local pressure pin 16 can be pushed in. In FIG. 4, even in a portion outside the range of the thick solid line, there is a condition that no defect is recognized by X-ray evaluation and a high quality with a specific gravity of 2.73 g / cm ³ or more is obtained. When the average indentation speed V of 16 exceeds 2.63 mm / s, the indentation speed of the local pressurizing pin 16 is too high with respect to the solidification interface moving speed, and the local pressurizing pin 16 reaches the stroke end before shrinkage occurs. May be pushed in. Therefore, in order to stably obtain high quality in mass production, it is desirable to avoid this condition as much as possible.

  On the other hand, when the indentation speed V is 1.2 mm / s or less, solidification proceeds and the indentation resistance becomes excessive, and the local pressure pin 16 may not be able to be pushed to a sufficient depth. Therefore, it is desirable to avoid this condition as much as possible in order to stably obtain high quality in mass production. In addition, if the indentation depth of the local pressure pin 16 is shallow, there is a tendency that the shrinkage nest is not crushed. Therefore, the indentation depth is controlled by controlling the indentation speed of the local pressure pin 16. This is an important requirement for reliably closing the coagulation contraction space (which becomes a shrinkage nest).

Therefore, according to this embodiment described above, the following operational effects can be obtained.
According to the present embodiment, the molten metal 12 pressurized and filled in the mold 11 is subjected to solidification shrinkage in the solidification process, and thus a portion where a casting defect (shrinkage) is likely to occur, that is, the boss portion 1B of the compressor housing 1 is It can be die-cast by pressing with the local pressure pin 16.
At this time, the local pressure pin 16 is made to follow based on the movement of the solidification interface obtained by the solidification interface movement speed of the molten metal calculated in advance, and is continuously pushed in until the solidification is completed. The local pressure pin 16 can be pushed in according to the solidification timing. For this reason, it is possible to reliably close the coagulation contraction space (which becomes the shrinkage nest) in a region where the shrinkage nest is likely to occur, and to suppress the occurrence of the shrinkage nest.

  Therefore, the generation of shrinkage cavities accompanying solidification shrinkage can be eliminated or reduced to a very small amount, and a healthy housing 1 free from shrinkage cavities can be manufactured. In addition, this makes it possible to greatly improve the yield during die casting and to provide the high-quality housing 1 at a low cost. In particular, in the compressor housing 1 used as a pressure vessel, a screw hole or a through hole is often cut after casting into a thick boss portion 1B where shrinkage cavities are likely to occur. For this reason, even if the outer surface is clean, if there is a shrinkage nest inside it, it will be exposed to the cutting surface and cause refrigerant gas leakage. Since the amount can be reduced to a very small amount, a highly airtight housing free from refrigerant leakage can be obtained.

  In addition, since the pressurization by the local pressurization pin 16 is started 0.4 to 1.4 seconds after the completion of the filling of the molten metal, the local pressurization pin 16 is made to follow the movement of the solidification interface and surely. Can continue to be pushed in until solidification is complete. Therefore, the pressurization start by the local pressurization pin 16 is too early, and the local pressurization pin 16 is pushed to the stroke end, and the local pressurization pin 16 cannot be continuously pushed until the solidification is completed. In addition, the pressurization start is too late, and the indentation depth of the local pressurization pin 16 becomes shallow, so that the shrinkage nest defect cannot be sufficiently crushed, and the shrinkage nest is eliminated or reduced to a very small amount. be able to.

  Moreover, since the average pushing speed V of the local pressurizing pin 16 is set to 1.2 mm / s <V <2.63 mm / s, the local pressurizing pin 16 is made to follow the movement of the solidification interface of the molten metal 12 to be sure. In addition, it is possible to continue to push until the solidification is completed, and to push into the position where the shrinkage can be sufficiently crushed. Therefore, the local pressure pin 16 can be pushed to a sufficient depth over several seconds at an appropriate speed by following the movement of the solidification interface. For this reason, the coagulation contraction space (which becomes a shrinkage nest) can be reliably closed, and the generation or shrinkage of the shrinkage nest can be reliably eliminated.

Further, when locally pressurizing a portion where a casting defect (shrinkage cavity) is likely to occur, an overflow portion 11B is provided in the mold 11 and the overflow portion 11B is pressed by the local pressurizing pin 16, so that die casting is performed. It is possible to prevent pressurization marks due to local pressurization from occurring on the product, that is, the housing 1 side. Therefore, it is possible to eliminate the restriction on the part to be locally pressurized and to manufacture a higher quality die-cast product having no pressure mark.

In the above-described embodiment, the local pressurizing device 10 configured to push the local pressurizing pin 16 by the pressurizing cylinder 14 using hydraulic pressure has been described. However, the present invention is not limited to this, and an electric local pressure device may be used in which an electric servomotor is used, and its rotational drive is converted into a linear motion by a ball screw shaft so as to push in the local pressure pin 16.
Further, although the compressor housing 1 has been illustrated as an aluminum die-cast product, the present invention is not limited to this, and it goes without saying that the present invention can be applied to various aluminum die-cast products such as an aluminum alloy cylinder, a crankcase, or a transmission case.

It is sectional drawing of the aluminum die-cast product (compressor housing) manufactured with the manufacturing method and apparatus of the aluminum die-cast product which concerns on one Embodiment of this invention. It is a partial schematic block diagram of the manufacturing apparatus of the aluminum die-cast product which concerns on one Embodiment of this invention. It is explanatory drawing of the solidification closed loop formation condition of the local pressurization part estimated by the analysis of the manufacturing method of the aluminum die-casting product concerning one Embodiment of this invention. It is explanatory drawing of the quality investigation result of the local pressurization prototype by the manufacturing method of the aluminum die-casting product which concerns on one Embodiment of this invention.

Explanation of symbols

1 Compressor housing (aluminum die-cast product)
1B Boss (site where casting defects are likely to occur)
DESCRIPTION OF SYMBOLS 10 Die-cast manufacturing apparatus 11 Mold 11B Overflow part 12 Molten metal 13 Local pressurization apparatus 14 Pressurization cylinder 15 Piston 16 Local pressurization pin 22 Control apparatus

Claims (7)

In the method of manufacturing an aluminum die-cast product, where the molten metal pressure-filled in the mold is subjected to solidification shrinkage in the solidification process, a portion where casting defects are likely to occur is pressed with a local pressure pin and die-cast.
A method of manufacturing an aluminum die cast product, wherein the local pressurizing pin is made to follow based on movement of a solidification interface obtained by a solidification interface movement speed of the molten metal calculated in advance and is continuously pushed in until solidification is completed.   The method for producing an aluminum die-cast product according to claim 1, wherein the pressurization by the local pressurization pin is started 0.4 to 1.4 seconds after the completion of the filling of the molten metal.   3. The method for producing an aluminum die-cast product according to claim 1, wherein an average indentation speed V of the local pressure pin is 1.2 mm / s <V <2.63 mm / s.   The method for manufacturing an aluminum die-cast product according to any one of claims 1 to 3, wherein the aluminum die-cast product is a pressure vessel.   The said pressure vessel is a housing of a compressor, The manufacturing method of the aluminum die-cast product of Claim 4 characterized by the above-mentioned. In an aluminum die casting product manufacturing apparatus in which a molten metal filled in a mold is subjected to solidification and shrinkage in the solidification process, and a portion where a casting defect is likely to occur is pressed by a local pressure pin and die-cast.
A local pressure pin that is provided corresponding to the portion where the casting defect is likely to occur, and locally pressurizes the portion;
A pushing means for pushing the local pressure pin toward the part;
A controller that controls the pushing means, and causes the local pressure pin to follow the movement of the solidification interface obtained by the solidification interface movement speed of the molten metal calculated in advance, and to keep pushing until the solidification completion time point. Aluminum die-cast product manufacturing equipment characterized by the above. Corresponding to the portion where the casting defect is likely to occur, the mold is provided with an overflow portion,
Attached to the overflow part so that the local pressure pin can be pushed,
The apparatus for producing an aluminum die-cast product according to claim 6, wherein the overflow portion is locally pressurized by the local pressure pin.

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