DIE CASTING MACHINE

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2024-088024 filed on May 30, 2024, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present specification discloses a die casting machine that has a circulation channel for cooling a die.

2. Description of Related Art

In general, a die casting machine is provided with a circulation channel through which a coolant circulates. The circulation channel passes through the die, and the coolant flowing through the circulation channel cools the die, and hence a product in the die.

For example, Japanese Unexamined Patent Application Publication No. 2009-202196 (JP 2009-202196 A) discloses a die cooling mechanism for causing a cooling medium to flow to a die. The die cooling mechanism in JP 2009-202196 A has a coolant channel, and this coolant channel has an outbound channel for guiding the cooling medium to the die, a return channel for guiding the cooling medium exiting the die, and a bypass channel for connecting the outbound channel and the return channel on the outside of the die. In JP 2009-202196 A, when there is no need to cool the die, the connection between the outbound channel and the die is closed off and the cooling medium is made to flow to the bypass channel, thereby suppressing excessive cooling of the die.

SUMMARY

Now, in recent years, manufacturing large-sized products by die casting has been proposed. When casting large-sized products, the die casting machine itself becomes large, the circulation channel through which the coolant flows becomes long, and the flow rate of the coolant also increases. Thus, there is a problem in that responsivity of flow rate control of the coolant is poor immediately following starting the die casting machine.

Accordingly, the present specification discloses a die casting machine in which the responsivity of the flow rate control of the coolant is improved immediately following starting of the die casting machine.

A die casting machine disclosed in the present specification includes a main circulation channel through which a coolant, for cooling a die, circulates, a main pump that feeds the coolant to the main circulation channel, a sub-circulation channel through which the coolant circulates, the sub-circulation channel being shorter than the main circulation channel, and a sub-pump for feeding the coolant to the sub-circulation channel.

In this case, the main circulation channel may include an outbound channel for guiding the coolant toward the die, and a return channel for guiding the coolant exiting the die,

• • the sub-circulation channel may branch from the return channel and merge with the outbound channel, and
  • the sub-pump may be provided on the sub-circulation channel, and feed the coolant from the return channel to the outbound channel via the sub-circulation channel.

Also, the die casting machine may further include a first check valve and a second check valve that are disposed in a vicinity of a merging point of the outbound channel and the sub-circulation channel,

• • the first check valve may be disposed on the outbound channel, at a position upstream of the merging point in a flow direction of the outbound channel, and
  • the second check valve may be disposed on the sub-circulation channel, at a position upstream of the merging point in a flow direction of the return channel.

Also, output of the sub-pump may be smaller than output of the main pump.

Also, the die casting machine may further include

• • a safety fence separating a non-work area and a work area,
  • a main flowmeter that is disposed in the work area and that measures a flow rate of the main circulation channel, and
  • a sub-flowmeter that is disposed in the non-work area and that measures a flow rate of the sub-circulation channel, in which
  • part of the main circulation channel may pass through the work area, and the sub-circulation channel does not have to pass through the work area.

Also, the die casting machine may further include a controller, in which

• • following activation of the die casting machine, the controller may cause the coolant to flow into the sub-circulation channel in an initial shot, and cause the coolant to flow into the main circulation channel in second and subsequent shots, or when temperature of the coolant flowing into the sub-circulation channel exceeds a reference value.

Another die casting machine disclosed in the present specification includes a circulation channel through which a coolant for cooling a die circulates, a plurality of flowmeters for measuring a flow rate in the circulation channel, and a safety fence for separating a work area and a non-work area, in which at least part of the flowmeters is disposed in the non-work area, and a remaining part is disposed in the work area.

According to the die casting machine disclosed in the present specification, the responsivity of the flow rate control of the coolant immediately following starting is further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:

FIG. 1 is a diagram illustrating a configuration of a cooling circuit of a die casting machine;

FIG. 2 is a diagram illustrating a flow of a coolant immediately after starting;

FIG. 3 is a view showing the flow of the coolant after closing the sub-circulation channel; and

FIG. 4 is a diagram illustrating a configuration of another cooling circuit.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the configuration of the die casting machine 10 will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a cooling circuit 20 of a die casting machine 10. The die casting machine 10 is an apparatus for performing die casting processing. For example, the die casting machine 10 is a device for integrally casting large parts used in vehicles and aircraft, and is a device called a megacast machine or a gigacast machine.

The die casting machine 10 has a die 12. In FIG. 1, the die 12 is illustrated as a single block, but in practice, the die 12 has a fixed die and a movable die. The fixed die and the movable die can be moved closer to each other and apart from each other, and the movable die is clamped to the fixed die to form a cavity space for obtaining a cast article. The molten metal is injected into the cavity space and filled. Hereinafter, the step of injecting the molten metal into the cavity space to fill the cast article is referred to as a “shot”.

The die 12 is replaced according to the type of cast article to be manufactured. Further, since the die 12 is subjected to a heat load and a pressure load at each shot, it gradually deteriorates by repeating the shot. Therefore, even if there is no change in the type of the cast article, the die 12 is replaced periodically or in accordance with the degree of deterioration. All of the dies 12 may be replaced, or only a part thereof may be replaced. For example, if the die 12 has a nest in contact with the cavity space and a mother die holding the nest, only the nest may be replaced.

The die casting machine 10 has a cooling circuit 20 for cooling the die 12. The cooling circuit 20 is roughly divided into an in-die channel 30, a main circulation channel 22, and a sub-circulation channel 50. The in-die channel 30 is formed inside the die 12, and is a channel through which the coolant flows. In FIG. 1, two linear in-die channels 30 are illustrated, but in practice, the in-die channels 30 branch more frequently and are flexed in a complex manner depending on the shape of the cast article.

The main circulation channel 22 is a channel that communicates with the in-die channel 30 and circulates the coolant. The main circulation channel 22 has an outbound channel 26 through which the coolant flows toward the in-die channel 30, and a return channel 28 through which the coolant exits from the in-die channel 30 flows. Here, as shown in FIG. 1, the in-die channel 30 is divided into a plurality of systems (two in the illustrated example). In order to communicate with each of the plurality of in-die channels 30, the terminal end portion of the outbound channel 26 and the start end portion of the return channel 28 are also divided into a plurality of systems.

Both the outbound channel 26 and the return channel 28 are provided outside the die 12. Therefore, even when a part or all of the die 12 is replaced, the outbound channel 26 and the return channel 28 do not need to be changed. Hereinafter, the connection portion between the outbound channel 26 and the in-die channel 30 is referred to as an “inlet connector 32”, and the connection portion between the in-die channel 30 and the return channel 28 is referred to as an “outlet connector 34”.

The main circulation channel 22 further includes a main pump 36, a heat exchanger 38, a tank 24, a main flowmeter 40, and a main valve 42. The main pump 36 is a pump that sends the coolant to the in-die channel 30 through the outbound channel 26. The tank 24 temporarily stores the coolant recovered through the return channel 28. The coolant stored in the tank 24 is pumped up by the main pump 36, and is again supplied to the in-die channel 30 through the outbound channel 26. The heat exchanger 38 cools the coolant recovered from the in-die channel 30 until the coolant reaches a predetermined temperature by exchanging heat with the outside air or the coolant. The heat exchanger 38 is provided in the middle of the path of the return channel 28.

The main flowmeter 40 is a sensor that measures the flow rate of the coolant flowing in the main circulation channel 22, specifically, the return channel 28. Here, the start end portion of the return channel 28 is divided into a plurality of systems as shown in FIG. 1. The main flowmeter 40 is provided in each of the return channels 28 of the plurality of systems. As a result, the flow rate can be measured for each of the plurality of in-die channels 30.

The main valve 42 is disposed in each of the plurality of return channels 28 in the vicinity of the main flowmeter 40. The main valve 42 is a valve that opens and closes each of the corresponding return channels 28. The main valve 42 is a solenoid valve that is electrically opened and closed in response to a control signal output from the controller 66. The main valve 42 may also be a control valve capable of controlling flow rate and/or pressure. The controller 66 switches the opening/closing amount of the main valve 42 according to the progress of die casting. The configuration of the main circulation channel 22 described so far is an example. The main circulation channel 22 may have any other configuration as long as it can circulate the coolant flowing through the die 12. For example, the heat exchanger 38 and the tank 24 described above may be omitted.

The cooling circuit 20 further includes a sub-circulation channel 50. The sub-circulation channel 50 is a channel through which the coolant flows, and is a shorter channel than the main circulation channel 22. The sub-circulation channel 50 branches off from the return channel 28 of the main circulation channel 22 and merges with the outbound channel 26. As described above, since the terminal end portion of the outbound channel 26 is divided into a plurality of systems, the terminal end portion of the sub-circulation channel 50 that merges with the outbound channel 26 is also divided into a plurality of systems. Further, since the start end portion of the return channel 28 is divided into a plurality of systems, the start end portion of the sub-circulation channel 50 branched from the return channel 28 is also divided into a plurality of systems. The reason why the sub-circulation channel 50 is provided will be described in detail later.

A sub-flowmeter 56 and a sub-valve 58 are provided at each of the start ends of the sub-circulation channels 50 of the plurality of systems. The sub-flowmeter 56 has a wireless communication function of transmitting and receiving signals using radio waves or infrared rays. As the standard of the radio communication, for example, WiFi (registered trademark) or Bluetooth (registered trademark) can be adopted. The sub-flowmeter 56 uses this wireless communication function to communicate with the controller 66. The sub-valve 58 is provided at each of the starting ends of the sub-circulation channels 50 of the plurality of systems, and is a valve that opens and closes a corresponding system. The sub-valve 58 has a wireless communication function similar to the sub-flowmeter 56 and is a remotely operable solenoid valve. The sub-valve 58, like the main valve 42, may be a control valve capable of controlling flow rate and/or pressure. Further, a sub pump 54 is provided in the middle of the sub-circulation channel 50. The sub-pump 54 sends the coolant along the sub-circulation channel 50. The sub-pump 54 is smaller in size and lower in output than the main pump 36.

As will be described in detail later, the sub-pump 54 is driven in a state where the sub-valve 58 is opened immediately after the die casting machine 10 is started up. As a result, the coolant flows into the sub-circulation channel 50 after flowing through the in-die channel 30, and returns from the sub-circulation channel 50 to the in-die channel 30 again. In other words, immediately after the rise, the coolant circulation channel is formed by the in-die channel 30 and the sub-circulation channel 50. In order to maintain the circulation channel, check valves 60 and 62 are provided in the vicinity of the merging point 52 of the outbound channel 26 and the sub-circulation channel 50. The first check valve 60 is provided on the upstream side of the outbound channel 26 slightly from the merging point 52. The first check valve 60 allows flow from upstream to downstream (i.e., flow from the main pump 36 to the die 12), while prohibiting flow from downstream to upstream. The second check valve 62 is provided on the upstream side of the return channel slightly from the merging point 52 in the sub-circulation channel 50. The second check valve 62 allows flow from the sub-circulation channel 50 toward the outbound channel 26, while prohibiting flow from the outbound channel 26 toward the sub-circulation channel 50.

A part of the main circulation channel 22 passes through the work area Aw, but the sub-circulation channel 50 does not pass through the work area Aw. That is, the periphery of the die casting machine 10 that handles the high-temperature molten metal becomes a non-work area An in which the entry of persons is prohibited during the die-casting process. Around the die casting machine 10, a safety fence 64 is arranged to separate the non-work area An from the work area Aw permitted to enter the human body. Each of the sub-circulation channel 50, the sub-flowmeter 56, the sub-valve 58, and the sub-pump 54 is disposed on the non-work area An inside the safety fence 64. On the other hand, a part of the main circulation channel 22, the main flowmeter 40, and the main valve 42 are disposed in the work area Aw. As a result, the operator can directly access the main flowmeter 40 and the main valve 42 during the die casting execution period, and can operate the main valve 42 and monitor the flow rate of the coolant as necessary.

The controller 66 controls driving of the die casting machine 10. The controller 66 is physically a computer having a processor 67 and a memory 68. Although the controller 66 is illustrated as a single computer in FIG. 1, the controller 66 may include a plurality of physically separate controllers 66. The controller 66 controls the driving of the pumps 36 and 54 and the valves 42 and 58 according to the progress of the die casting and the detection results of the flowmeters 40 and 56. More specifically, the controller 66 drives the pumps 36, 54 and the valves 42, 58 so that the coolant circulates through the sub-circulation channel 50 immediately after the rising of the die casting machine 10, and thereafter the coolant circulates without passing through the sub-circulation channel 50, which will be described later.

Next, the reason for providing the sub-circulation channel 50 will be described. When die casting is performed, the main pump 36 is driven to adjust the die 12 to a desired temperature. As a result, the coolant is sent to the in-die channel 30. By adjusting the flow rate of the coolant, the die 12 is adjusted to a desired temperature. For example, when the molten metal is injected into the die 12, the die 12 needs to be adjusted to a temperature such that the molten metal flows smoothly in the cavity space while the molten metal is not baked on the die 12. On the other hand, after filling the molten metal, it is necessary to quickly cool the die 12 so that the molten metal solidifies quickly. Therefore, after the filling of the molten metal, the controller 66 controls the main pump 36 or the main valve 42 or both based on the flow rate measured by the main flowmeter 40 so that a larger amount of the coolant flows into the in-die channel 30 than before the filling.

As described above, both the main flowmeter 40 and the main pump 36 are disposed outside the safety fence 64 and are separated from the die 12. In particular, in an integral casting method of a large part called megacast or gigacast, the entire die casting machine 10 is very large, and the distance of the main circulation channel 22 and the flow rate of the coolant to be flowed are also very large. Therefore, the time until the pressure of the main pump 36 is transmitted to the in-die channel 30 immediately after the start of the die casting machine 10 and the time until the flow rate of the in-die channel 30 can be measured by the main flowmeter 40 are both long. As a result, when the sub-circulation channel 50 is not utilized, the responsiveness of the flow rate control of the coolant is poor immediately after the activation of the die casting machine 10.

Therefore, in the present example, as described above, the sub-circulation channel 50 is provided that branches from the return channel 28 of the main circulation channel 22 and returns to the outbound channel 26. As described above, the sub-circulation channel 50 passes through the vicinity of the die 12 without passing through the work area Aw. Therefore, the distance of the sub-circulation channel 50 is significantly shorter than that of the main circulation channel 22. Immediately after the start-up of the die casting machine 10, the coolant is pumped by the sub-pump 54 provided in the sub-circulation channel 50, whereby the flow of the coolant through the in-die channel 30 can be formed at an early stage, and the die 12 can be cooled at an early stage.

More specifically, the main circulation channel 22 and the sub-circulation channel 50 are already filled with the coolant at a stage before starting the die casting machine 10. In this state, when the die casting machine 10 is activated, the controller 66 drives both the main pump 36 and the sub-pump 54 with the main valve 42 and the sub-valve 58 open.

FIG. 2 is a diagram showing the flow of the coolant at this time. As shown in FIG. 2, in this case, each of the main pump 36 and the sub pump 54 pumps the coolant. However, since the main pump 36 is separated from the in-die channel 30, it takes time for the output pressure of the main pump 36 to be transmitted to the in-die channel 30. On the other hand, since the sub pump 54 is close to the in-die channel 30, the output pressure of the sub pump 54 reaches the in-die channel 30 at an early stage. Therefore, immediately after the start-up of the die casting machine 10, the coolant is sent from the in-die channel 30 to the sub-circulation channel 50 by the output pressure of the sub-pump 54, and then goes to the outbound channel 26. The coolant flowing into the outbound channel 26 is prevented from flowing back by the first check valve 60, and therefore flows back into the in-die channel 30. As described above, by driving the sub-pump 54, the flow circulating through the sub-circulation channel 50 and the in-die channel 30 is established at an early stage after the start of the die casting machine 10, and the cooling (or temperature adjustment) of the die 12 can be started at an early stage.

At this time, the flow rate of the coolant flowing in the sub-circulation channel 50 is quickly measured by the sub-flowmeter 56 disposed in the vicinity of the die 12. The measurement by the sub-flowmeter 56 is transmitted to the controllers 66 in the work area Aw by radio communication. The controller 66 wirelessly changes the opening degree of the sub valve 58 in accordance with the flow rate of the received coolant.

Here, the heat exchanger 38 is not provided in the sub-circulation channel 50, and the circulation path is also short. Therefore, in the sub-circulation channel 50 alone, the temperature of the circulating coolant becomes high at an early stage. Therefore, the controller 66 closes the sub-valve 58 and stops the driving of the sub-pump 54 after the first shot is completed or when the temperature of the coolant flowing through the sub-circulation channel 50 exceeds the reference value. FIG. 3 is a diagram showing the flow of the coolant at this time.

As shown in FIG. 3, in this case, the coolant flows out of the in-die channel 30, and then does not proceed to the sub-circulation channel 50, but proceeds to the return channel 28. Thereafter, the coolant flows again from the return channel 28 to the in-die channel 30 through the heat exchanger 38, the tank 24, the main pump 36, and the outbound channel 26. The coolant is sufficiently dissipated in this process. Therefore, even if the shot is repeated thereafter, the coolant that has been sufficiently cooled is sent to the in-die channel 30, so that the die 12 can be appropriately cooled.

As is apparent from the above description, in the present example, immediately after the activation of the die casting machine 10, the sub-circulation channel 50 is opened and the sub pump 54 is driven to form a flow circulating through the sub-circulation channel 50 and the in-die channel 30. Thus, even immediately after the start-up of the die casting machine 10, the coolant can be sent to the in-die channel 30 at an early stage, and the die 12 can be appropriately cooled. In particular, in the present embodiment, since the sub-circulation channel 50 does not pass through the work area Aw away from the die casting machine 10, the sub-circulation channel 50 can be shortened. Therefore, it is possible to effectively prevent the deterioration of the responsiveness of the flow rate control of the coolant.

When the die 12 is removed from the die casting machine 10 in order to replace the die 12, the coolant in the in-die channel 30 may be purged while the coolant is filled in the main circulation channel 22 and the sub-circulation channel 50. That is, when the die 12 is removed from the die casting machine 10, the coolant in the in-die channel 30 is discharged to the outside in a state where the inlet connector 32 and the outlet connector 34 are closed. After the in-die channel 30 becomes empty, the die 12 is removed from the die casting machine 10. As described above, by using the configuration in which only the coolant in the in-die channel 30 is purged, it is possible to eliminate the time for refilling the coolant in the main circulation channel 22 and the sub-circulation channel 50, and it is possible to shorten the replacement time of the die 12.

Further, any of the configurations described above is an example, and other configurations may be changed as long as the configuration described in claim 1 is provided. For example, in the above explanation, the sub-circulation channel 50 and the sub-flowmeter 56 are both disposed in the non-work area An, and a part of the main circulation channel 22 and the main flowmeter 40 are disposed in the work area Aw. However, a portion of the sub-circulation channel 50 or the sub-flowmeter 56 may be disposed in the work area Aw, or both the main circulation channel 22 and the main flowmeter 40 may be disposed in the non-work area An.

Further, in the above description, after the delivery of the coolant by the main pump 36 is stabilized, the sub valve 58 is closed to stop the driving of the sub pump 54. However, the sub-pump 54 may be driven even after the sub-valve 58 is closed. For example, as shown in FIG. 4, the die 12 includes a component called a sleeve bushing 14. The sleeve bushing 14 is a generally cylindrical part that surrounds the periphery of an injection sleeve (not shown). The sleeve bushing 14 needs to be cooled during a period in which cooling of the cast article is not required, for example, during die clamping or injection. In order to cool the sleeve bushing 14, as shown in FIG. 4, a local channel 70 may be provided that branches from the sub-circulation channel 50, passes through the sleeve bushing 14, and returns to the sub-circulation channel 50. Further, a third flowmeter 72 and a third valve 74 for measuring the flow rate in the local channel 70 are arranged in the local channel 70. The second check valve 62 is a solenoid valve that can be completely closed.

When the flow rate of the main pump 36 is stabilized, the controller 66 closes the sub-valve 58 and the second check valve 62 and continues to drive the sub-pump 54 with the third valve 74 opened. As a result, a flow in which the coolant circulates between the sub-circulation channel 50 and the local channel 70 is established. As a result, the sleeve bushing 14 is cooled by the sub-pump 54. Although the circulation path for cooling the sleeve bushing 14 is short, the sleeve bushing 14 has a smaller heat capacity than the entire die 12, so that the sleeve bushing 14 can be cooled appropriately even in this short circulation path.