JP4810706B2 - Die casting apparatus and die casting method - Google Patents

Description

  The present invention relates to a die casting apparatus and a die casting method for molding a die cast metal product, and more particularly to a vacuum die casting apparatus and a vacuum die casting method that enable a molten metal to be injected at a low speed and a low pressure.

In the field of automobile development, lightweight metal molding technology has been developed from the perspective of reducing vehicle weight and improving engine efficiency, and the use of light metals for the engine, chassis and body that account for the majority of vehicle weight. Has been tried.
An aluminum alloy can be cited as a lightweight metal expected to be applied to these, and its practical application to engines and chassis is progressing. With regard to the development of the body, which is a larger part, there have been practical examples so far in Europe and the United States where automobiles in which the entire vehicle body is made of aluminum have been developed. In Japan, there are also examples of trial production or small-scale production of automobiles in which the entire vehicle body is made of aluminum.
However, in each example, a large number (for example, 300 points) of individual parts such as press plate, wrought material, and cast material are combined or joined together, which hinders high-cost and low-productivity walls. In rare cases, production has not yet expanded.

  In order to overcome this high cost and low productivity technical barrier, innovative development of die casting technology is indispensable. If the development of die casting technology capable of manufacturing thin, large, and complex parts enables the entire vehicle body to be molded at a low cost with a significantly smaller number of parts (for example, 30 points), the vehicle weight will increase significantly. Reduction can be achieved, and it is possible not only to improve the performance of automobiles but also to have a positive impact on the global environment, such as reducing the amount of exhaust gas.

FIG. 12 is a schematic view showing a conventional die casting apparatus with a vacuum apparatus.
The die casting apparatus shown in FIG. 12 includes a movable mold and a fixed mold disposed on the opposite side of the movable mold. When the movable mold and the fixed mold are clamped, a cavity is formed at the boundary between the movable mold and the fixed mold. The cavity mimics the outer contour of the desired product.
The die casting apparatus includes a plunger. The plunger is provided in the movable mold, and the distal end portion of the plunger communicates with the cavity through the runner. The plunger is filled with a molten metal, and when the plunger is operated, the molten metal is injected into the cavity and filled into the cavity.

The injection port of the plunger is disposed at a position away from the cavity via the runner and the gate. An overflow, a vacuum valve, and a suction path are provided in the vicinity of the edge of the cavity opposite to the injection port of the plunger. A vacuum generator (not shown) such as a vacuum pump is disposed downstream of the suction path, and the vacuum generator sucks air in the cavity.
When the plunger operates and the molten metal is injected from the plunger into the cavity via the runner and the gate, the molten metal enters the cavity, the overflow, and the vacuum valve from the edge of the cavity. The molten metal that has entered is detected by a sensor, and by this detection, the vacuum valve is closed to prevent the molten metal from entering the vacuum generator.

The fixed die is provided with a pressure pin and the movable die is provided with an extrusion pin.
When the molten metal fills the cavity, the pressure pin is activated to further pressurize the cavity and prevent solidification shrinkage at the solidification delay site. Thereafter, when the molten metal is solidified in the cavity (C) and the molding is completed, the movable mold (F) and the stationary mold (S) are separated from each other in the mold opening process. And an extrusion pin (E) act | operates, the product shape | molded from the fixed metal mold | die (S) is extruded, and a die-cast metal product is taken out from a die-cast apparatus (M).

In the die casting apparatus (M) shown in FIG. 12, it is necessary to inject the molten metal from the plunger (P) at a high speed and a high pressure. Because, as described above, the molten metal is also injected into the cavity through the metal plunger that performs injection, the runner and gate for controlling and distributing the flow of the molten metal and eliminating inclusions and impurities in the molten metal. As a result, the molten metal needs to flow over a long distance in the mold, and cooling proceeds rapidly. If the molten metal is solidified before the molten metal flows and completely fills the cavity (C), a desired product shape cannot be obtained.
On the other hand, high-speed injection causes air entrainment, and high pressure (for example, a molten metal pressure of 500 atm) is required for injection in order to crush the bubbles. Therefore, a huge die-casting machine and a mold that enable high speed and high pressure are required, and the cost must be high. Therefore, for the purpose of reducing entrained air, a complicated and expensive vacuum valve will be introduced. However, solidification is fast and sufficient vacuum suction time cannot be taken. There is a problem that a sufficient degree of vacuum cannot be achieved due to gas generation from the agent and lubricant.

Such high-speed and high-pressure injection of molten metal also causes many quality problems in the die casting technology.
For example, Patent Document 1 and Patent Document 2 show that such high-speed and high-pressure injection causes turbulent flow of molten metal in the cavity (C), resulting in insufficient gas in the cavity (C). It refers to causing omissions. Further, Patent Documents 1 and 2 mention that this insufficient outgassing appears as bubbles in the die cast product, leading to a deterioration in the quality of the die cast product.
In addition, Patent Document 1 and Patent Document 2 introduce a non-porous die casting method for replacing the inside of the cavity (C) with an active gas and a method for decompressing the inside of the cavity as a countermeasure against this insufficient gas escape. When such a countermeasure method is adopted, there are problems that the structure of the die casting apparatus becomes complicated and that the molten metal is cooled and solidified in the sleeve of the plunger (P) while the inside of the cavity (C) is depressurized. To mention.
Further, Patent Document 3 refers to the problem of load on the plunger (P) due to high-speed and high-pressure injection.

JP 60-83762 A JP 2005-329464 A JP-A-5-69104

  As exemplified in Patent Documents 1 to 3, it is known that injection of molten metal under high-speed and high-pressure conditions has caused many problems in the die-casting technology. Injecting molten metal to obtain die-cast products has not been successful. In fact, in order to cope with the problems exemplified in Patent Documents 1 to 3, the inventions disclosed in Patent Documents 1 to 3 solve the respective problems on the premise of injection of molten metal under high speed and high pressure conditions. ing.

However, at present, the technology that is truly desired is to obtain a die-cast product by performing injection under low-speed and low-pressure conditions. The present invention performs injection under low-speed and low-pressure conditions, and casts such as entrainment and shrinkage nests. An object of the present invention is to provide a die casting apparatus and a die casting method capable of obtaining a high-quality thin-walled die-cast product without defects.
Furthermore, an object of the present invention is to provide a die casting apparatus and a die casting method capable of performing injection under a low speed / low pressure condition to obtain a large thin molded article such as an automobile body.
In addition, an object of the present invention is to provide a die casting apparatus having a simple and small structure.
Furthermore, an object of the present invention is to provide a die casting apparatus that enables appropriate and precise control according to the type of product.

The invention according to claim 1 is a die casting apparatus for molding a die-cast product by filling a cavity with a molten metal, and the die casting apparatus includes a movable mold and a fixed mold that define a cavity shape filled with the molten metal. And a main sleeve connected to the fixed mold and communicated with the cavity. The main injector is connected to the fixed mold and has one end and a cylindrical sleeve extending outward from the fixed mold. And a columnar plunger tip arranged inside the sleeve, and an actuator fixed to the other end of the sleeve and moving the plunger tip within the sleeve, and connected to the vacuum generator inside the sleeve In the cavity formed when the plunger tip is in the retracted position, the metal melt is formed. A die casting apparatus characterized by but is housed is held thermal insulation capsule.
According to a second aspect of the present invention, the capsule includes a box-shaped container portion having a cross section that is substantially the same shape and the same size as a cross section of the inner space of the sleeve, and a filter portion that covers a cavity side end of the container, 2. The die casting apparatus according to claim 1, wherein the container portion is made of a heat insulating material.

The invention according to claim 3 further includes a sub-injector, wherein the sub-injector is connected to the fixed mold and one end, and has a cylindrical sleeve extending outward from the fixed mold, and inside the sleeve. A columnar plunger tip arranged and an actuator that is fixed to the other end of the sleeve and moves the plunger tip within the sleeve, and is connected to the vacuum generator inside the sleeve of the sub-injector The die casting apparatus according to claim 1, wherein a mouth is formed.
A fourth aspect of the present invention is the die casting apparatus according to the first aspect, wherein the main injector is located inward of a region surrounded by the outer peripheral edge of the cavity.
A fifth aspect of the present invention is the die casting apparatus according to the third aspect, wherein the sub-injector is located inward of a region surrounded by the outer peripheral edge of the cavity.
A sixth aspect of the present invention is the die casting apparatus according to the first aspect, comprising a plurality of the main injectors.
A seventh aspect of the present invention is the die casting apparatus according to the third aspect, comprising a plurality of the sub-injectors.

The invention according to claim 8 is the die casting apparatus according to claim 1, further comprising a decompression sensor, wherein the decompression sensor measures the degree of vacuum in the cavity.
The invention according to claim 9 is further provided with a position sensor, and the position sensor measures the position of the plunger tip.
A tenth aspect of the present invention is the die casting apparatus according to the first aspect, further comprising a pressure sensor, wherein the pressure sensor measures a pressure in the cavity.
The invention according to claim 11 is the die casting apparatus according to claim 1, further comprising a temperature sensor, wherein the temperature sensor measures the temperature in the cavity.
According to a twelfth aspect of the present invention, there is provided a decompression sensor that measures the degree of vacuum in the cavity, a position sensor that measures the position of the plunger tip, a pressure sensor that measures the pressure in the cavity, and a temperature in the cavity. And a signal from at least one selected from the group consisting of the pressure sensor, the pressure sensor, the pressure sensor, and the temperature sensor, and a signal corresponding to the received signal 2. The die casting apparatus according to claim 1, further comprising a control panel that transmits to the actuator, wherein the actuator operates based on the transmitted signal.
In a thirteenth aspect of the invention, the sub-injector outputs a signal corresponding to a signal received by the control panel from at least one selected from the group consisting of the pressure reduction sensor, the position sensor, the pressure sensor, and the temperature sensor. The die casting apparatus according to claim 12, wherein the actuator of the sub-injector is operated based on the transmitted signal.

The invention according to claim 14 is the die casting apparatus according to claim 1, wherein the main injector is disposed at a final solidification position where the molten metal filled in the cavity is solidified last.
The invention according to claim 15 is the die casting apparatus according to claim 1, wherein the main injector is arranged at an optimum filling position where the flow distance of the molten metal flowing in the cavity is the shortest.
The invention according to claim 16 is characterized in that the main injector is disposed at a position where force is applied to a portion that requires the most force when the die-cast product is detached from the fixed mold. It is a die casting device.

  According to a seventeenth aspect of the present invention, there is provided a hot water supply process for supplying a molten metal to a main injector of a die casting apparatus, a vacuum process for reducing the pressure in a cavity formed at a boundary between a movable mold and a fixed mold of the die casting apparatus, An injection process for injecting molten metal supplied from an injector and filling the cavity with molten metal, and applying pressure to the molten metal filled in the cavity and pressurizing to solidify the molten metal in the cavity A die casting method comprising: a step, and an extruding step of extruding a die-cast product formed by solidifying in the cavity after separating the movable mold and the fixed mold, wherein the main injector includes the fixed mold A cylindrical sleeve connected to the mold and one end and extending outward from the fixed mold, and a columnar shape arranged inside the sleeve A plunger tip and an actuator that is fixed to the other end of the sleeve and moves the plunger tip within the sleeve. In the hot water supply step, a molten metal is formed in a space surrounded by the sleeve inner wall and the plunger tip upper surface The die-casting method is characterized in that a heat-insulating capsule in which is held is supplied.

The invention according to claim 18 is characterized in that the vacuum process includes a step of measuring the degree of vacuum in the cavity, and the injection process is performed after confirming that the degree of vacuum in the cavity is equal to or lower than a predetermined value. The die casting method according to claim 17, wherein the die casting method is started.
The invention according to claim 19 is characterized in that the injection step includes a step of compressing the heat insulating capsule between the upper surface of the plunger and the movable mold and injecting a molten metal from the heat insulating capsule. A die casting method according to claim 17.
The invention according to claim 20 is the die casting method according to claim 17, wherein the pressurizing step includes a step of solidifying the molten metal in a state where the heat insulating capsule remains in the molten metal. It is.
The invention according to claim 21 is the die casting method according to claim 17, wherein the extrusion step includes a step of applying vibration to the die cast product.
The invention according to claim 22 is the die casting method according to claim 17, wherein the extrusion step includes a step of displacing the plunger tip upward, and the plunger tip extrudes the die cast product from the cavity. is there.

According to the first and second aspects of the present invention, the molten metal is disposed in the heat insulating capsule, whereby the suction port is provided in the sleeve, the air in the cavity is sucked from the suction port, and the pressure in the cavity is reduced. Is possible. When the pressure is reduced, the air flow toward the suction port passes around the heat insulating capsule and does not cause a problem of sucking the molten metal. Therefore, it is possible to perform suitable gas venting before and during the molten metal injection. Furthermore, since the molten metal inside the heat-insulating capsule is difficult to be cooled, it is possible to take a long suction time, and it is possible to ensure a much higher vacuum state in the cavity as compared with the prior art. That is, in the prior art, it is necessary to perform an immediate injection process after pouring, so the suction time is inadequate and the amount of leakage is large due to the complexity of the mold structure. Due to the generation of gas from the agent, the degree of vacuum was about 0.5 to 0.1 atmosphere, but according to the present invention, a high vacuum pressure of 0.1 to 0.01 atmosphere or less can be achieved. It becomes. This high vacuum enables the vacuum degassing process previously performed in the melting process to be performed in the die-casting device. In addition to the filter effect, a very normal molten metal is directly injected into the cavity. Is possible.
For this reason, in this invention, it becomes possible to arrange | position a main injector to a cavity center position, for example, and it becomes possible to aim at reduction of the flow distance in the cavity of a molten metal. For example, when trying to obtain a molded product in the form of a thin bar, in the prior art, the maximum flow distance of the molten metal was equal to the total length of the sleeve, the runner, and the molded product. Or less than half of the length of the molded product. Therefore, in the present invention, it is not necessary to inject the molten metal under high-pressure and high-speed conditions in order to prevent incomplete filling in the cavity. It becomes possible to obtain a high-quality molded product by injecting molten metal that does not deteriorate. In addition, since the runner or overflow that plays the role of distributing the molten metal, removing inclusions in the molten metal, and removing the initial supercooled molten metal is not necessary, the yield of the product can be greatly improved.
Since the injection molding can be performed at a low speed and a low pressure, the mechanical strength of the die casting apparatus itself is not required. Therefore, the die casting apparatus itself can be reduced in size.
Further, the main plunger itself can play the roles of vacuum, injection, pressurization and extrusion shown in FIG. Therefore, the structure of the die casting apparatus can be simplified as compared with the prior art.
As described above, the simplification and miniaturization of the structure of the die casting apparatus can reduce the number of seals and ensure a high degree of vacuum. Therefore, there are no defects caused by air entrainment. In addition, a high pressure for crushing the entrained air (conventionally, for example, a molten metal pressure of 500 atm) is not required, and a low pressure (50 atm or less) for compensating for solidification shrinkage is sufficient.

According to the invention described in claim 3, the sub-injector increases the pressure in the cavity after the molten metal is filled, and cooperates with the main injector to contribute to the extrusion of the molded product and execute a suitable extrusion operation. Is possible.
According to the invention described in claim 4, it is possible to suitably extrude the die-cast product from the cavity using the main injector.
According to the invention described in claim 5, it is possible to suitably extrude the die-cast product from the cavity using the sub-injector.
According to the sixth aspect of the present invention, it is possible to integrally manufacture a large molded product by optimally arranging the plurality of main injectors at necessary positions.
According to the seventh aspect of the present invention, it is possible to integrally manufacture a large molded product by optimally arranging the plurality of sub-injectors at the necessary positions.
According to the eighth to eleventh aspects, it is possible to collect parameter data of manufacturing process conditions in each molding process before injection, during injection, and after injection.
According to the inventions of claims 12 and 13, the actuator can be controlled based on parameter data of manufacturing process conditions in each molding process before injection, in the middle of injection, and after injection, and molding processing under precise control Can be performed.
According to the invention described in claims 14 to 16, it is possible to realize suitable injection, pressurization and extrusion.

According to the seventeenth aspect of the present invention, the molten metal is disposed in the heat-insulating capsule, thereby preventing a problem that the molten metal is sucked in the vacuum process. Therefore, it is possible to perform suitable gas venting before and during the molten metal injection. Furthermore, since the molten metal inside the heat-insulating capsule is difficult to be cooled, it is possible to take a long suction time, and it is possible to ensure a much higher vacuum state in the cavity as compared with the prior art. This high vacuum enables the vacuum degassing process previously performed in the melting process to be performed in the die-casting device. In addition to the filter effect, a very normal molten metal is directly injected into the cavity. Is possible.
According to the invention described in claim 18, it is possible to confirm that a defect has occurred in the decompression process, and it is possible to correct the defect and stop the injection process, thereby avoiding the production of defective products. Become.
According to the present invention, the structure of the die casting apparatus can be simplified.
According to the twenty-first aspect of the present invention, the die-cast product can be taken out without causing deformation or cracking in the die-cast product.

Hereinafter, embodiments of a die casting apparatus according to the present invention will be described with reference to the drawings. In the following embodiments, the die casting apparatus is shown using a horizontal division type apparatus, but a vertical division type apparatus is also included in the technical scope of the present invention.
FIG. 1 is a schematic view of a die casting apparatus according to the present invention. 1A is a plan view of a fixed mold of the die casting apparatus of the present invention, and FIG. 1B is a cross-sectional view of the die casting apparatus taken along line AA of FIG. (C) is sectional drawing of the die-cast apparatus in the BB line of Fig.1 (a).
The die casting apparatus (1) of the present invention is connected to a movable mold (2), a fixed mold (3) disposed below the movable mold (2), and a fixed mold (3), A main injector (4) and a sub-injector (5).

The movable mold (2) and the fixed mold (3) are clamped in an overlapping state, and a cavity (6) is formed at the boundary surface between the movable mold (2) and the fixed mold (3). The cavity (6) has substantially the same shape as the outer contour of the desired die-cast product.
In the example shown in FIG. 1, the concave portion (61) is formed on the upper surface of the fixed mold (3), the lower surface of the movable mold (2) is formed flat, and the fixed mold (3) defining the shape of the concave portion (61). ) And the lower surface of the movable mold (2) form a cavity (6), but the present invention is not limited to this, and the concave mold (61) is provided on the movable mold (2) side. The shape and type of the desired die-cast product can be formed in a form in which the upper surface of the fixed mold (3) is formed flat and a form in which the concave mold (61) is formed in both the movable mold (2) and the fixed mold (3). Depending on the situation, it can be appropriately adopted. Further, in the figure, a single mold (2, 3) is shown, but it is also possible to use an additional mold depending on the desired shape and type of die-cast product. include.

In the example shown in FIG. 1A, the recess (61) is formed in a substantially rectangular shape in plan view, but the shape in plan view of the recess (61) is appropriately determined according to the shape of the desired die-cast product. It is done.
A packing groove is formed on the upper surface of the fixed mold (3) so as to surround the recess (61), and a heat-resistant packing (31) is arranged in the packing groove. When the movable mold (2) and the fixed mold (3) are clamped and pressed against each other, the heat-resistant packing (31) is compressed and deformed, and exhibits high sealing performance against the cavity (6). .

  An injection port (34) connected to the main injector (4) is formed substantially at the center of the recess (61). Moreover, the opening part (35) connected to a subinjector (5) is formed in the corner | angular corner part of a recessed part (61).

As shown in FIG. 1B, the main injector (4) includes a cylindrical sleeve (41). An upper end portion (411) of the sleeve (41) is fixed to the fixed mold (3) to form an injection port (34).
The sleeve (41) extends downward from the lower surface of the fixed mold (3). An actuator is attached to the lower end (412) of the sleeve (41). In the example shown in FIG. 1, an electric servo cylinder (42) is used as the actuator.

A plunger tip (43) is disposed inside the sleeve (41). In the example shown in FIG. 1B, the upper part (431) and the lower part (432) of the plunger tip (43) are formed larger in diameter than the intermediate part (433) between the upper part (431) and the lower part (432). Is done.
In the example shown in FIG. 1B, a gap of 0.05 mm or more and 0.1 mm or less is provided between the outer peripheral surface of the upper portion (431) of the plunger tip (43) and the inner peripheral surface of the sleeve (41). Further, a vacuum seal material (434) is disposed between the outer peripheral surface of the lower portion (432) of the plunger tip (43) and the sleeve (41), and the vacuum seal material (434) serves as the lower portion (432) of the plunger tip (43). It is compressed and deformed between the outer peripheral surface and the sleeve (41) and exhibits high hermetic sealing performance.

In the example shown in FIG. 1B, most of the rod (421) of the electric servo cylinder (42) is housed in the electric servo cylinder main body (422), and the rod of the electric servo cylinder (42). The plunger tip (43) connected to (421) is in the retracted position. In this specification, the retracted position does not mean the lower limit position of the mechanical operation range, but means the position where the plunger tip (43) is retracted from the cavity in the molding process.
Since the plunger tip (43) is formed shorter than the sleeve (41), when the plunger tip (43) is at the lowest position, a space is formed on the upper portion of the sleeve (41). The heat insulating capsule (7) is disposed in the formed space. The heat insulating capsule (7) accommodates the molten metal therein and exhibits high heat insulating performance so as to prevent the temperature of the molten metal from decreasing.

A suction port (44) is provided inside the sleeve (41), and the suction port (44) is connected to a vacuum generator (not shown) such as a vacuum pump.
When the vacuum generator is activated, the gas inside the die casting apparatus (1) is released to the outside of the die casting apparatus (1) through the suction port (44). As described above, since there is no cooling of the molten metal, a sufficient suction time can be secured, and in addition, a vacuum is formed between the lower portion (432) of the plunger tip (43) and the inner peripheral surface of the sleeve (41). Since the seal (434) is arranged and exhibits high hermetic sealing performance, a large amount of gas is sucked from the cavity (6), and the inside of the cavity (6) can be kept in a high vacuum state. Thereby, formation of the bubble in a die-cast product can be prevented suitably.
As described above, the gas flows from the cavity (6) to the suction port (44). A heat insulating capsule (7) exists in the middle of the flow path of the gas body. Since the molten metal is held inside the heat insulating capsule (7), the molten metal is not sucked into the suction port by suction. Further, since the heat insulating capsule (7) exhibits high heat insulating performance, even if the heat insulating capsule (7) is exposed to this gas flow, the temperature of the molten metal inside the heat insulating capsule (7) is reduced. There is no. Furthermore, the molten metal is degassed under a high vacuum, and the molten metal can be cleaned.

FIG. 2 is an enlarged view of the sub-injector (5) shown in FIG. 1 (c).
The sub injector (5) has substantially the same structure as the main injector (4). The sub-injector (5) includes a cylindrical sleeve (51). The upper end (511) of the sleeve (51) is fixed to the stationary mold (3), and the internal space of the sleeve (51) communicates with the cavity (6) through the opening (35).
The sleeve (51) extends downward from the lower surface of the fixed mold (3). An actuator is attached to the lower end (512) of the sleeve (51). In the example shown in FIGS. 1 and 2, an electric servo cylinder (52) is used as the actuator.

A plunger tip (53) is disposed inside the sleeve (51). In the example shown in FIG. 1C and FIG. 2, the upper portion (531) and the lower portion (532) of the plunger tip (53) have a diameter larger than the intermediate portion (533) between the upper portion (531) and the lower portion (532). Largely formed.
In the example shown in FIGS. 1C and 2, a gap of 0.05 mm or more and 0.1 mm or less is provided between the outer peripheral surface of the upper portion (531) of the plunger tip (53) and the inner peripheral surface of the sleeve (51). It is done. Further, a vacuum seal material (534) is disposed between the outer peripheral surface of the lower portion (532) of the plunger tip (53) and the sleeve (51), and the vacuum seal material (534) serves as the lower portion (532) of the plunger tip (53). It is compressed and deformed between the outer peripheral surface and the sleeve (51) and exhibits high hermetic sealing performance.

A suction port (54) is provided inside the sleeve (51), and the suction port (54) is connected to a vacuum generator (not shown) such as a vacuum pump.
When the vacuum generator is activated, the gas inside the die casting apparatus (1) is released to the outside of the die casting apparatus (1) through the suction port (54). As described above, the vacuum seal (534) is disposed between the lower portion (532) of the plunger tip (53) and the inner peripheral surface of the sleeve (51), and exhibits high hermetic sealing performance. A lot of gas is sucked, and the inside of the cavity (6) can be depressurized. Thereby, formation of the bubble in a die-cast product can be prevented suitably.
In this embodiment, a decompression sensor is attached to at least one of the suction port (44) of the main injector (4) and the suction port of the sub-injector (5), and the degree of vacuum in the cavity (6) can be measured. is there.

FIG. 3 is a detailed view of the heat-insulating capsule (7).
The heat-insulating capsule (7) of the present embodiment is formed in a bottomed cylindrical shape, a container part (71) formed in a box shape capable of accommodating a molten metal, and a filter that closes the upper end opening of the container part (71) Part (72). The inner space of the heat insulating capsule (7) is filled with molten metal.
The container part (71) is made of a glass fiber heat-resistant cloth or a molded body made of heat-resistant ceramic fiber, and the molten metal filled in the container part (71) leaks through the peripheral wall part or the bottom part of the container part (71). I will not put it out.
A large number of openings (73) having a diameter of 0.5 mm or less are provided in the filter part (72), and impurities such as aluminum oxide existing in the molten metal can be filtered. The filter part (72) may be formed from the same material as the container part (71), or may be formed from a porous ceramic filter, a wire mesh, or the like.
In addition, the cross section of the heat insulating capsule (7) is formed in substantially the same shape and the same size as the cross section of the internal space of the sleeve (1).

FIG. 4 is a flowchart showing an outline of the flow of a manufacturing process for manufacturing a die-cast product. The die-cast product is manufactured through a hot water supply process, a vacuum process, a filling process, a pressing process, and an extrusion process.
In the hot water supply step, the molten metal held in the heat insulating capsule (7) is loaded into the die casting apparatus (1), and the state shown in FIG. 1 is obtained. Alternatively, the container part (71) of the heat insulating capsule (7) is arranged in the die casting apparatus (1), and then the molten metal is supplied into the heat insulating capsule (7), and then the die casting apparatus by the filter part (72). (1) The cavity (6) side opening of the heat-insulating capsule (7) arranged in the inside may be closed with the filter part (72).
As another method, when the suction in the cavity (6) is not performed from the main injector (4), but suction is performed only from other parts, for example, the sub-injector (5), the sleeve ( 41) is made of a highly heat-insulating material, and the molten metal is supplied to the space surrounded by the upper surface of the plunger tip (43) and the inner wall of the sleeve (41), and then the filter part (72) is arranged in the space. Also good.

FIG. 5 shows the operation of the die casting apparatus (1) in the vacuum process. 5A shows the operation of the main injector (4), and FIG. 5B shows the operation of the sub-injector (5).
In the vacuum process, the vacuum generator connected to the main injector (4) and the sub-injector (5) is activated, the gas in the cavity (6) is discharged from the suction ports (44, 54), and the cavity (6) is decompressed. Is done.
After confirming that the inside of the cavity (6) is sufficiently decompressed using the decompression sensor (81), the injection process is performed.

FIG. 6 shows the operation of the die casting apparatus (1) in the injection process. 6A shows the operation of the main injector (4), and FIG. 6B shows the operation of the sub-injector (5).
In the injection process, the electric servo cylinder (42) of the main injector (4) is operated, and the rod (421) of the electric servo cylinder (42) extends upward. As a result, the plunger tip (43) arranged in the sleeve (41) moves upward and pushes up the heat-insulating capsule (7) upward. The heat insulating capsule (7) is compressed between the upper surface of the plunger tip (43) and the lower surface of the movable mold (2).
As a result of the compression of the heat insulating capsule (7), the molten metal flows out of the insulating capsule (7), and the discharged molten metal is filled into the cavity (6). Impurities in the molten metal remain at the position where the heat insulating capsule (7) exists because the flow is hindered on the wall of the container (71) of the filter part (72) and the heat insulating capsule (7).
As shown in FIG. 6 (b), when the molten metal is completely filled in the cavity (6), the sleeve (51) of the sub-injector (5) passes through the opening (35) formed in the stationary mold (3). The molten metal flows into the upper space, and the molten metal fills the space above the sleeve (51).

FIG. 7 shows the operation of the die casting apparatus (1) in the pressurizing step.
In the pressurizing step, the electric servo cylinder (52) of the sub-injector (5) is operated, and the rod (521) of the electric servo cylinder (52) extends upward. As a result, the molten metal that has flowed into the space surrounded by the inner wall of the sleeve (51) and the upper surface of the plunger tip (53) shown in FIG. 6 (b) is pushed back into the cavity (6). The molten metal is pressurized, filling the cavity (6) is promoted, coagulation shrinkage is compensated, and the generation of shrinkage nests is prevented. In this state, the molten metal is cooled and solidified and molded into a die-cast product (100).

FIG. 8 is a diagram showing an extrusion process. FIG. 8A shows the operation of the main injector (4), and FIG. 8B shows the operation of the sub-injector (5). Note that the mold opening operation is performed before the extrusion process is executed. Therefore, in FIG. 8, the movable mold (2) is removed.
After the molten metal is solidified in the cavity (6), an extrusion process is performed through a mold opening operation. In the extrusion process, the electric servo cylinder (42) of the main injector (4) and the electric servo cylinder (52) of the sub-injector (5) are operated, and the rods (421, 521) of these electric servo cylinders (42, 52) are operated. Extending upward, the plunger tip (43, 53) disposed in the sleeve (41, 51) is pushed upward.
As a result, the die-cast product (100) is pushed out from the concave portion (61) of the fixed mold (3), and the die-cast product (100) is taken out from the die-casting device (1).

As shown in FIG. 8A, the heat-insulating capsule (7) forms a part of the die-cast product (100). The heat insulating capsule (7) is subject to compression by the plunger tip (43), but raises a portion of the die cast product (100). In the prior art, the pressure part of the die casting apparatus requires a thick biscuit part in order to maintain the pressurizing effect. However, in the present invention, the biscuit part is sufficiently kept warm, so the biscuit part is different from the prior art. And thin.
However, due to the presence of the heat-insulating capsule (7), the part has a larger wall thickness than the other parts, regardless of the presence of impurities in the molten metal whose flow is prevented by the filter part (73). High strength can be maintained. Further, unlike the prior art, since there are no biscuit part, runner part and overflow part, the yield is good, and removal processing for these is unnecessary.
The appearance problem can be solved by using the die-cast product (100). For example, when the die-cast product (100) is a body of an automobile, there is no appearance problem if it is used so that the raised portion appears on the back of the body. Alternatively, it is possible to cut and remove the raised portion as long as the mechanical strength is allowed. Moreover, depending on the case, it is also possible to arrange | position and remove a filter part in the outer side adjacent part of die-cast product (100).
In the present invention, since a large-sized die-cast product (100) of a lightweight metal can be integrally formed, even if the weight of a part of the die-cast product (100) is increased by the raised portion, the overall weight reduction effect is achieved. The contribution to is great.

As described above, in this embodiment, the main injector (4) is arranged at a position that supports the center position of the die-cast product (100), and the four sub-injectors (5) are corner portions of the die-cast product (100). It is arranged in the position which supports each. Therefore, in the extrusion process, the die-cast product (100) is stably detached from the recess (61) and lifted.
Actually, the shape of the die-cast product (100) is often complicated, but in such a case, the molten metal solidifies the position of the main injector (4) and the sub-injector (5) most slowly. Considering the final solidification position and the flow of the molten metal in the cavity (6), the most suitable position for filling in the cavity (6) (for example, the position where the flow of the molten metal is the shortest) It is easy to determine the optimum position of the main injector (4) and the sub-injector (5) in consideration of the main injector (4) and the sub-injector (5) and the extrusion of the die-cast product (100). It becomes. This makes it possible to manufacture complex and large die-cast products. Moreover, it becomes easy to add or change according to the result at the time of prototyping. On the other hand, according to the prior art, it is very difficult to provide an injection function at the final solidification position or the optimal flow position, and to add or change this.
When the die-cast product (100) has a complicated shape, a portion requiring a large force locally occurs when the die-cast product (100) is pushed out from the recess (61) (for example, a rib formed on a flat plate). Site). The main injector (4) and the sub-injector (5) may be arranged so as to directly apply the pushing force to such a portion. Thereby, it becomes possible to perform an extrusion process smoothly and to prevent generation | occurrence | production of inferior goods, such as a deformation | transformation of a die-cast product (100).

The flow of the main molding process and the operation of the die casting apparatus (1) at each stage of the molding process have been described with reference to FIGS. 4 to 8. As shown in FIG. The operation of the cylinders (42, 52) may be controlled.
In the example shown in FIG. 9, the die casting apparatus (1) includes a control panel (8). Further, the die casting device (1) includes a position sensor (82) for detecting the positions of the plunger tip (43) of the main injector (4) and the plunger tip (53) of the sub-injector (5), and the degree of vacuum in the cavity (6). A pressure sensor (81) for detecting the pressure of the molten metal, a pressure sensor (83) for detecting the pressure of the molten metal, and a temperature sensor (84) for detecting the temperature of the molten metal.

The position sensor (82) detects the position of the plunger tip (43) and transmits a signal corresponding to the position of the plunger tip (43) to the control panel (8). The control panel (8) receives a signal from the position sensor (82), and grasps the current position of the plunger tip (43, 53) based on the received signal. Then, the difference between the position of the plunger tip (43, 53) required in the next step and the current position is calculated, and the rod (421, 421) of the electric servo cylinder (42, 52) is calculated by a length corresponding to the calculated value. 521) is expanded and contracted.
The position sensor (82) may measure the extension length of the rods (421, 521) of the electric servo cylinder (42, 52) instead of detecting the position of the plunger tip (43). Good.

As described above, the decompression sensor (81) is used to measure the degree of vacuum in the cavity (6). In the present embodiment, the suction ports (44, 44) of the main injector (4) and the sub-injector (5) are used. 54). In the die casting apparatus (1) of the present invention, the main plunger (4) can execute the securing of the degree of vacuum, injection, pressurization, and extrusion, respectively. There is no need to provide a dedicated member for each of the pressure and extrusion processes. Therefore, the structure of the die casting apparatus (1) is very simplified, and the sealing structure for making the inside of the cavity (6) of the die casting apparatus (1) in a vacuum state can be greatly simplified.
Therefore, it is possible to reliably and quickly ensure the degree of vacuum of the cavity (6). Therefore, after the degree of vacuum is measured by the decompression sensor (81) and it is confirmed that the inside of the cavity (6) has been sufficiently decompressed, it is possible to proceed to the next injection step.
In the prior art, for example, even if there was a decompression failure, injection could not be stopped, resulting in producing a defective product, but in the present invention, even if a failure occurs in the decompression process, It is possible to secure a spare time for correcting this. Alternatively, it is possible to take out the heat-insulating capsule (7) from the die-casting device (1) without starting the injection process, and start manufacturing the die-cast product (100) again from the hot water supply process. Therefore, in the present invention, defective products are not produced.

The pressure sensor (83) is arranged between the lower surface of the plunger tip (43) of the main plunger (4) and the rod (421) of the electric servo cylinder (42), and the pressure of the molten metal filled in the cavity (6). Is used to measure After the injection process, it is confirmed that the pressure of the molten metal in the cavity (6) measured by the pressure sensor (83) has exceeded a predetermined threshold for the molten metal pressure previously input to the control panel (8). If 8) judges, it will move to a pressurization process.
In order to proceed to the pressurizing step, the control panel (8) sends signals to the electric servo cylinder (42) of the main injector (4) and the electric servo cylinder (52) of the sub-injector (5), and the plunger tip (43, 53) is displaced upward.
The temperature sensor (84) measures the temperature of the molten metal. In the pressurizing step, after the plunger tip (43, 53) is displaced by a predetermined amount, this state is maintained for a predetermined time. The temperature sensor (84) monitors the temperature of the molten metal during this period, and the control panel (8) is based on a signal received from the temperature sensor (84) and has a predetermined value with respect to the molten metal temperature previously input to the control panel (9). If it is determined that the measured molten metal temperature has fallen below, a display for notifying the operator that the mold can be opened is displayed.

FIG. 10 is a chart showing an embodiment of the operation of the die casting apparatus (1). The horizontal axis of the chart is the time axis, and the vertical axis of the chart is the stroke length (unit: mm) of the rod (421, 521) of the electric servo cylinder (42, 52) calculated from the position sensor (82). It is. The chart also shows a data line indicating the increase / decrease of the pressure measured by the pressure sensor (84) along with the data line indicating the stroke length.
Prior to the vacuum process, a heat-insulating capsule (7) filled with molten metal is loaded into the main injector (4). Thereafter, the movable mold (2) and the fixed mold (3) are clamped. Then, the vacuum generator connected to the suction ports (44, 54) of the main injector (4) and the sub-injector (5) is operated to start the vacuum process.

  In the vacuum process, the gas in the cavity (6) is sucked and the cavity (6) is depressurized. The degree of decompression in the cavity (6) is monitored by the decompression sensor (81), and after confirming that the cavity (6) is sufficiently decompressed, the injection process is started.

After confirming that the pressure in the cavity (6) is sufficiently reduced, the injection process is started.
When the injection process is started, the plunger tip (43) of the main injector (4) is displaced upward. With the displacement of the plunger tip (43), the pressure of the molten metal also increases.
As shown in FIG. 10, after the start of the injection process, the plunger tip (43) is displaced upward at a speed of about 20 mm / second in the first stroke length of 15 mm. This prepares for injection. In the subsequent stroke length of 65 mm, the plunger tip (43) is displaced upward at a speed of about 100 mm / second. Thereby, the molten metal is injected into the cavity (6) from the heat insulating capsule (7).
Thus, the present invention can inject molten metal at a very low speed.

When the plunger tip (43) reaches a predetermined position, the pressurizing process is started. In the pressurizing step, the plunger tip (43) of the main injector (4) is displaced slightly upward while maintaining a predetermined pressure. Further, the plunger tip (53) of the sub-injector (5) is also displaced upward. During the pressurizing step, the pressure of the molten metal is kept in the range of 50 atm or less. In the conventional die casting apparatus, the pressure of the molten metal during the pressurizing step is about 500 atm. However, in the present invention, it is not necessary to generate a large pressure in the molten metal, and the pressure is low enough to compensate for the solidification shrinkage. Pressure is sufficient.
After the pressurizing step, the positions of the plunger tip (43) of the main injector (4) and the plunger tip (53) of the sub-injector (5) are maintained for about 10 seconds. During this time, the pressure of the molten metal gradually decreases. Thereafter, a mold opening operation is performed, and the movable mold (2) is separated from the fixed mold (3).

After the mold opening operation is completed, an extrusion process is performed.
In the extrusion process, the electric servo cylinder (42) of the main injector (4) and the electric servo cylinder (52) of the sub-injector (5) gradually move the plunger tip (43) while applying vibration to the plunger tip (43, 53). 53) is displaced upward. Although mold release resistance is generated during the extrusion process, the magnitude of this pressure depends on the shape of the die-cast product (100), the draft of the fixed mold (3), and the like. In the present invention, by giving vibration, the mold release resistance can be reduced and the die-cast product (100) is not deformed or cracked.
When the extrusion process is completed, the die-cast product (100) is taken out from the die-casting device (1). Thereafter, the die casting apparatus (1) is cleaned, a release agent is applied, and the next molding cycle is started.

FIG. 11 shows an application form for molding a large die-cast product (100) which is thin (1 to 2 mm), has a large and complicated shape and requires high strength and high quality, such as an automobile monocoque body panel. Show. FIG. 11A is a plan view of the die casting apparatus (1), and FIG. 11B is a cross-sectional view of the die casting apparatus (1).
Since the die-casting device (1) of the present invention can mold a die-cast product under low-speed and low-pressure conditions as described above, a very simplified structure can be adopted. Therefore, as shown in FIG. 11, the form which comprises a large sized movable metal mold | die (2) and a fixed metal mold | die (3) is employable. Further, a plurality of main injectors (4) and sub-injectors (5) are provided in the mold constituting the fixed mold (3), and the injection port (34) and the like are arranged at appropriate positions according to the shape of the cavity (6). A pressure point can be provided.
Furthermore, as shown in FIG. 11 (a), not only inside the area surrounded by the outer periphery of the cavity (6), but also an area outside the area surrounded by the outer periphery of the cavity (6) as necessary. A main injector (4) and a sub-injector (5) may be provided in the vicinity of the region. Even in this case, the main injector (4) exhibits four functions of vacuum, injection, pressurization and extrusion, and the sub-injector (5) exhibits three functions of vacuum, pressurization and extrusion. It becomes.

  The present invention can be suitably used for molding light metals such as aluminum and magnesium.

It is a figure which shows the die-casting apparatus which concerns on this invention. It is an enlarged view of the subinjector of the die-cast apparatus shown in FIG. It is sectional drawing of the heat insulation capsule with which the die-casting apparatus shown in FIG. 1 is loaded. It is a flowchart of the shaping | molding process using the die-cast apparatus shown in FIG. It is a figure which shows operation | movement of the die-casting apparatus in the vacuum process shown in FIG. It is a figure which shows operation | movement of the die-casting apparatus in the injection | emission process shown in FIG. It is a figure which shows operation | movement of the die-casting apparatus in the pressurization process shown in FIG. It is a figure which shows operation | movement of the die-casting apparatus in the extrusion process shown in FIG. It is a figure which shows the control system of the die-casting apparatus which concerns on this invention. It is a chart figure which shows the operation | movement data of the die-casting apparatus which concerns on this invention. It is an application form of the die casting apparatus according to the present invention. It is a figure which shows an example of the conventional die-casting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Die casting apparatus 100 ... Die casting product 2 ... Movable metal mold 3 ... Fixed metal mold 4 ... Main injector 41 ... Sleeve 42 ... · Electric servo cylinder 43 ··· Plunger tip 44 · · · Suction port 5 · · · Sub-injector 51 · · · Sleeve 52 · · · Electric servo cylinder 53 · · · Plunger tip 54 · · · ··· suction port 6 ··· cavity 7 ··· heat insulating capsule 71 ··· container portion 72 ··· filter portion 8 ··· control panel 81 ··· decompression sensor 82 .... Position sensor 83 ... Pressure sensor 84 ... Temperature sensor

Claims (22)

A die casting apparatus for molding a die-cast product by filling a metal melt into a cavity, the die casting apparatus comprising: a movable mold and a fixed mold for defining a cavity shape filled with the metal melt;
A main injector connected to the fixed mold and in communication with the cavity;
The main injector has a cylindrical sleeve connected to the fixed mold and one end and extending outward from the fixed mold;
A columnar plunger tip disposed inside the sleeve;
An actuator that is fixed to the other end of the sleeve and moves the plunger tip within the sleeve;
A suction port connected to a vacuum generator is formed inside the sleeve,
A die casting apparatus, wherein a heat insulating capsule holding the molten metal is accommodated in a cavity formed when the plunger tip is in a retracted position. The capsule is composed of a box-shaped container portion having a cross section substantially the same shape and size as the internal space cross section of the sleeve, and a filter portion covering the cavity side end of the container,
The die casting apparatus according to claim 1, wherein the container portion is made of a heat insulating material. A sub-injector,
The sub-injector has a cylindrical sleeve connected to the fixed mold and one end and extending outward from the fixed mold;
A columnar plunger tip disposed inside the sleeve;
An actuator that is fixed to the other end of the sleeve and moves the plunger tip within the sleeve;
The die casting apparatus according to claim 1, wherein a suction port connected to the vacuum generator is formed inside a sleeve of the sub-injector.   2. The die casting apparatus according to claim 1, wherein the main injector is located inward of a region surrounded by the outer peripheral edge of the cavity.   4. The die casting apparatus according to claim 3, wherein the sub-injector is positioned inward of a region surrounded by the outer peripheral edge of the cavity.   The die casting apparatus according to claim 1, comprising a plurality of the main injectors. The die casting apparatus according to claim 3, comprising a plurality of the sub-injectors. A pressure sensor,
2. The die casting apparatus according to claim 1, wherein the decompression sensor measures the degree of vacuum in the cavity. A position sensor;
2. The die casting apparatus according to claim 1, wherein the position sensor measures the position of the plunger tip. A pressure sensor,
2. The die casting apparatus according to claim 1, wherein the pressure sensor measures a pressure in the cavity. A temperature sensor;
2. The die casting apparatus according to claim 1, wherein the temperature sensor measures a temperature in the cavity. A decompression sensor for measuring the degree of vacuum in the cavity;
A position sensor for measuring the position of the plunger tip;
A pressure sensor for measuring the pressure in the cavity;
A temperature sensor for measuring the temperature in the cavity;
A control panel for receiving a signal from at least one selected from the group consisting of the decompression sensor, the position sensor, the pressure sensor, and the temperature sensor, and transmitting a signal corresponding to the received signal to the actuator; Prepared,
The die casting apparatus according to claim 1, wherein the actuator operates based on the transmitted signal. The control panel transmits a signal corresponding to a signal received from at least one selected from the group consisting of the pressure reduction sensor, the position sensor, the pressure sensor, and the temperature sensor to the actuator of the sub-injector,
The die casting apparatus according to claim 12, wherein the actuator of the sub-injector operates based on the transmitted signal.   2. The die casting apparatus according to claim 1, wherein the main injector is disposed at a final solidification position where the molten metal filled in the cavity is solidified last.   2. The die casting apparatus according to claim 1, wherein the main injector is disposed at an optimum filling position where a flow distance of the molten metal flowing in the cavity is the shortest.   2. The die casting apparatus according to claim 1, wherein the main injector is disposed at a position where a force is applied to a portion that requires the most force when the die casting product is detached from the fixed mold. A hot water supply process for supplying molten metal to the main injector of the die casting apparatus;
A vacuum process for reducing the pressure in the cavity formed at the boundary between the movable mold and the fixed mold of the die casting apparatus;
An injection step of injecting the molten metal supplied from the main injector, and filling the cavity with the molten metal;
A pressurizing step of applying pressure to the molten metal filled in the cavity and solidifying the molten metal in the cavity;
A die casting method comprising an extruding step of extruding a die cast product that is solidified in the cavity after separating the movable mold and the fixed mold,
The main injector has a cylindrical sleeve connected to the fixed mold and one end and extending outward from the fixed mold;
A columnar plunger tip disposed inside the sleeve;
An actuator that is fixed to the other end of the sleeve and moves the plunger tip within the sleeve;
In the hot water supplying step, a die-casting method, wherein a heat insulating capsule in which a molten metal is held is supplied to a space surrounded by the inner wall of the sleeve and the upper surface of the plunger tip. The vacuum process includes measuring a degree of vacuum in the cavity;
18. The die casting method according to claim 17, wherein the injection step is started after it is confirmed that the degree of vacuum in the cavity has become a predetermined value or less.   The die casting method according to claim 17, wherein the injection step includes a step of compressing the heat insulating capsule between the upper surface of the plunger and the movable mold and injecting a molten metal from the heat insulating capsule.   18. The die casting method according to claim 17, wherein the pressurizing step includes a step of solidifying the molten metal in a state where the heat insulating capsule remains in the molten metal.   The die casting method according to claim 17, wherein the extruding step includes a step of applying vibration to the die cast product.   The die casting method according to claim 17, wherein the extruding step includes a step of displacing the plunger tip upward, and the plunger tip extrudes the die cast product from the cavity.

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