Die Casting Machine

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

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

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.

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,

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,

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

Also, the die casting machine may further include

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

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.

Hereinafter, the configuration of the die casting machinewill be described with reference to the drawings.is a diagram illustrating a configuration of a cooling circuitof a die casting machine. The die casting machineis an apparatus for performing die casting processing. For example, the die casting machineis 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 machinehas a die. In, the dieis illustrated as a single block, but in practice, the diehas 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 dieis replaced according to the type of cast article to be manufactured. Further, since the dieis 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 dieis replaced periodically or in accordance with the degree of deterioration. All of the diesmay be replaced, or only a part thereof may be replaced. For example, if the diehas a nest in contact with the cavity space and a mother die holding the nest, only the nest may be replaced.

The die casting machinehas a cooling circuitfor cooling the die. The cooling circuitis roughly divided into an in-die channel, a main circulation channel, and a sub-circulation channel. The in-die channelis formed inside the die, and is a channel through which the coolant flows. In, two linear in-die channelsare illustrated, but in practice, the in-die channelsbranch more frequently and are flexed in a complex manner depending on the shape of the cast article.

The main circulation channelis a channel that communicates with the in-die channeland circulates the coolant. The main circulation channelhas an outbound channelthrough which the coolant flows toward the in-die channel, and a return channelthrough which the coolant exits from the in-die channelflows. Here, as shown in, the in-die channelis divided into a plurality of systems (two in the illustrated example). In order to communicate with each of the plurality of in-die channels, the terminal end portion of the outbound channeland the start end portion of the return channelare also divided into a plurality of systems.

Both the outbound channeland the return channelare provided outside the die. Therefore, even when a part or all of the dieis replaced, the outbound channeland the return channeldo not need to be changed. Hereinafter, the connection portion between the outbound channeland the in-die channelis referred to as an “inlet connector”, and the connection portion between the in-die channeland the return channelis referred to as an “outlet connector”.

The main circulation channelfurther includes a main pump, a heat exchanger, a tank, a main flowmeter, and a main valve. The main pumpis a pump that sends the coolant to the in-die channelthrough the outbound channel. The tanktemporarily stores the coolant recovered through the return channel. The coolant stored in the tankis pumped up by the main pump, and is again supplied to the in-die channelthrough the outbound channel. The heat exchangercools the coolant recovered from the in-die channeluntil the coolant reaches a predetermined temperature by exchanging heat with the outside air or the coolant. The heat exchangeris provided in the middle of the path of the return channel.

The main flowmeteris a sensor that measures the flow rate of the coolant flowing in the main circulation channel, specifically, the return channel. Here, the start end portion of the return channelis divided into a plurality of systems as shown in. The main flowmeteris provided in each of the return channelsof the plurality of systems. As a result, the flow rate can be measured for each of the plurality of in-die channels.

The main valveis disposed in each of the plurality of return channelsin the vicinity of the main flowmeter. The main valveis a valve that opens and closes each of the corresponding return channels. The main valveis a solenoid valve that is electrically opened and closed in response to a control signal output from the controller. The main valvemay also be a control valve capable of controlling flow rate and/or pressure. The controllerswitches the opening/closing amount of the main valveaccording to the progress of die casting. The configuration of the main circulation channeldescribed so far is an example. The main circulation channelmay have any other configuration as long as it can circulate the coolant flowing through the die. For example, the heat exchangerand the tankdescribed above may be omitted.

The cooling circuitfurther includes a sub-circulation channel. The sub-circulation channelis a channel through which the coolant flows, and is a shorter channel than the main circulation channel. The sub-circulation channelbranches off from the return channelof the main circulation channeland merges with the outbound channel. As described above, since the terminal end portion of the outbound channelis divided into a plurality of systems, the terminal end portion of the sub-circulation channelthat merges with the outbound channelis also divided into a plurality of systems. Further, since the start end portion of the return channelis divided into a plurality of systems, the start end portion of the sub-circulation channelbranched from the return channelis also divided into a plurality of systems. The reason why the sub-circulation channelis provided will be described in detail later.

A sub-flowmeterand a sub-valveare provided at each of the start ends of the sub-circulation channelsof the plurality of systems. The sub-flowmeterhas 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-flowmeteruses this wireless communication function to communicate with the controller. The sub-valveis provided at each of the starting ends of the sub-circulation channelsof the plurality of systems, and is a valve that opens and closes a corresponding system. The sub-valvehas a wireless communication function similar to the sub-flowmeterand is a remotely operable solenoid valve. The sub-valve, like the main valve, may be a control valve capable of controlling flow rate and/or pressure. Further, a sub pumpis provided in the middle of the sub-circulation channel. The sub-pumpsends the coolant along the sub-circulation channel. The sub-pumpis smaller in size and lower in output than the main pump.

As will be described in detail later, the sub-pumpis driven in a state where the sub-valveis opened immediately after the die casting machineis started up. As a result, the coolant flows into the sub-circulation channelafter flowing through the in-die channel, and returns from the sub-circulation channelto the in-die channelagain. In other words, immediately after the rise, the coolant circulation channel is formed by the in-die channeland the sub-circulation channel. In order to maintain the circulation channel, check valvesandare provided in the vicinity of the merging pointof the outbound channeland the sub-circulation channel. The first check valveis provided on the upstream side of the outbound channelslightly from the merging point. The first check valveallows flow from upstream to downstream (i.e., flow from the main pumpto the die), while prohibiting flow from downstream to upstream. The second check valveis provided on the upstream side of the return channel slightly from the merging pointin the sub-circulation channel. The second check valveallows flow from the sub-circulation channeltoward the outbound channel, while prohibiting flow from the outbound channeltoward the sub-circulation channel.

A part of the main circulation channelpasses through the work area Aw, but the sub-circulation channeldoes not pass through the work area Aw. That is, the periphery of the die casting machinethat 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, a safety fenceis 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, the sub-flowmeter, the sub-valve, and the sub-pumpis disposed on the non-work area An inside the safety fence. On the other hand, a part of the main circulation channel, the main flowmeter, and the main valveare disposed in the work area Aw. As a result, the operator can directly access the main flowmeterand the main valveduring the die casting execution period, and can operate the main valveand monitor the flow rate of the coolant as necessary.

The controllercontrols driving of the die casting machine. The controlleris physically a computer having a processorand a memory. Although the controlleris illustrated as a single computer in, the controllermay include a plurality of physically separate controllers. The controllercontrols the driving of the pumpsandand the valvesandaccording to the progress of the die casting and the detection results of the flowmetersand. More specifically, the controllerdrives the pumps,and the valves,so that the coolant circulates through the sub-circulation channelimmediately after the rising of the die casting machine, and thereafter the coolant circulates without passing through the sub-circulation channel, which will be described later.

Next, the reason for providing the sub-circulation channelwill be described. When die casting is performed, the main pumpis driven to adjust the dieto a desired temperature. As a result, the coolant is sent to the in-die channel. By adjusting the flow rate of the coolant, the dieis adjusted to a desired temperature. For example, when the molten metal is injected into the die, the dieneeds 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. On the other hand, after filling the molten metal, it is necessary to quickly cool the dieso that the molten metal solidifies quickly. Therefore, after the filling of the molten metal, the controllercontrols the main pumpor the main valveor both based on the flow rate measured by the main flowmeterso that a larger amount of the coolant flows into the in-die channelthan before the filling.

As described above, both the main flowmeterand the main pumpare disposed outside the safety fenceand are separated from the die. In particular, in an integral casting method of a large part called megacast or gigacast, the entire die casting machineis very large, and the distance of the main circulation channeland the flow rate of the coolant to be flowed are also very large. Therefore, the time until the pressure of the main pumpis transmitted to the in-die channelimmediately after the start of the die casting machineand the time until the flow rate of the in-die channelcan be measured by the main flowmeterare both long. As a result, when the sub-circulation channelis not utilized, the responsiveness of the flow rate control of the coolant is poor immediately after the activation of the die casting machine.

Therefore, in the present example, as described above, the sub-circulation channelis provided that branches from the return channelof the main circulation channeland returns to the outbound channel. As described above, the sub-circulation channelpasses through the vicinity of the diewithout passing through the work area Aw. Therefore, the distance of the sub-circulation channelis significantly shorter than that of the main circulation channel. Immediately after the start-up of the die casting machine, the coolant is pumped by the sub-pumpprovided in the sub-circulation channel, whereby the flow of the coolant through the in-die channelcan be formed at an early stage, and the diecan be cooled at an early stage.

More specifically, the main circulation channeland the sub-circulation channelare already filled with the coolant at a stage before starting the die casting machine. In this state, when the die casting machineis activated, the controllerdrives both the main pumpand the sub-pumpwith the main valveand the sub-valveopen.

is a diagram showing the flow of the coolant at this time. As shown in, in this case, each of the main pumpand the sub pumppumps the coolant. However, since the main pumpis separated from the in-die channel, it takes time for the output pressure of the main pumpto be transmitted to the in-die channel. On the other hand, since the sub pumpis close to the in-die channel, the output pressure of the sub pumpreaches the in-die channelat an early stage. Therefore, immediately after the start-up of the die casting machine, the coolant is sent from the in-die channelto the sub-circulation channelby the output pressure of the sub-pump, and then goes to the outbound channel. The coolant flowing into the outbound channelis prevented from flowing back by the first check valve, and therefore flows back into the in-die channel. As described above, by driving the sub-pump, the flow circulating through the sub-circulation channeland the in-die channelis established at an early stage after the start of the die casting machine, and the cooling (or temperature adjustment) of the diecan be started at an early stage.

At this time, the flow rate of the coolant flowing in the sub-circulation channelis quickly measured by the sub-flowmeterdisposed in the vicinity of the die. The measurement by the sub-flowmeteris transmitted to the controllersin the work area Aw by radio communication. The controllerwirelessly changes the opening degree of the sub valvein accordance with the flow rate of the received coolant.

Here, the heat exchangeris not provided in the sub-circulation channel, and the circulation path is also short. Therefore, in the sub-circulation channelalone, the temperature of the circulating coolant becomes high at an early stage. Therefore, the controllercloses the sub-valveand stops the driving of the sub-pumpafter the first shot is completed or when the temperature of the coolant flowing through the sub-circulation channelexceeds the reference value.is a diagram showing the flow of the coolant at this time.

As shown in, in this case, the coolant flows out of the in-die channel, and then does not proceed to the sub-circulation channel, but proceeds to the return channel. Thereafter, the coolant flows again from the return channelto the in-die channelthrough the heat exchanger, the tank, the main pump, and the outbound channel. 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, so that the diecan be appropriately cooled.

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

When the dieis removed from the die casting machinein order to replace the die, the coolant in the in-die channelmay be purged while the coolant is filled in the main circulation channeland the sub-circulation channel. That is, when the dieis removed from the die casting machine, the coolant in the in-die channelis discharged to the outside in a state where the inlet connectorand the outlet connectorare closed. After the in-die channelbecomes empty, the dieis removed from the die casting machine. As described above, by using the configuration in which only the coolant in the in-die channelis purged, it is possible to eliminate the time for refilling the coolant in the main circulation channeland the sub-circulation channel, and it is possible to shorten the replacement time of the die.

Further, any of the configurations described above is an example, and other configurations may be changed as long as the configuration described in claimis provided. For example, in the above explanation, the sub-circulation channeland the sub-flowmeterare both disposed in the non-work area An, and a part of the main circulation channeland the main flowmeterare disposed in the work area Aw. However, a portion of the sub-circulation channelor the sub-flowmetermay be disposed in the work area Aw, or both the main circulation channeland the main flowmetermay be disposed in the non-work area An.

Further, in the above description, after the delivery of the coolant by the main pumpis stabilized, the sub valveis closed to stop the driving of the sub pump. However, the sub-pumpmay be driven even after the sub-valveis closed. For example, as shown in, the dieincludes a component called a sleeve bushing. The sleeve bushingis a generally cylindrical part that surrounds the periphery of an injection sleeve (not shown). The sleeve bushingneeds 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, as shown in, a local channelmay be provided that branches from the sub-circulation channel, passes through the sleeve bushing, and returns to the sub-circulation channel. Further, a third flowmeterand a third valvefor measuring the flow rate in the local channelare arranged in the local channel. The second check valveis a solenoid valve that can be completely closed.

When the flow rate of the main pumpis stabilized, the controllercloses the sub-valveand the second check valveand continues to drive the sub-pumpwith the third valveopened. As a result, a flow in which the coolant circulates between the sub-circulation channeland the local channelis established. As a result, the sleeve bushingis cooled by the sub-pump. Although the circulation path for cooling the sleeve bushingis short, the sleeve bushinghas a smaller heat capacity than the entire die, so that the sleeve bushingcan be cooled appropriately even in this short circulation path.