Die-Casting Machine

This application claims priority to Japanese Patent Application No. 2024-067802 filed on Apr. 18, 2024, incorporated herein by reference in its entirety.

The present specification discloses a die-casting machine in which a flow path through which oil flows is formed in a sleeve.

Typically, a die-casting machine includes a sleeve that communicates with the cavity of a mold (see Japanese Unexamined Patent Application Publication No. 2021-505393 (JP 2021-505393 A), for example). Molten metal, which is a molten material, is supplied to the sleeve, and then supplied from the sleeve to the cavity of the mold by a plunger.

A flow path through which oil flows is occasionally formed in the sleeve. The sleeve is occasionally subjected to temperature adjustment performed using temperature adjustment oil, in order to suppress a reduction in the temperature of the molten metal supplied to the sleeve, for example. In this case, a flow path through which the temperature adjustment oil flows is formed in the sleeve.

The sleeve gradually deteriorates in the process of repeatedly injecting the molten metal. Therefore, the sleeve is replaced regularly or irregularly according to the degree of deterioration. If oil remains in the sleeve during this replacement, the oil leaks to the outside. Such leaking oil reduces the workability of the sleeve replacement, and contaminates the surrounding environment.

Thus, it is conceivable to purge (remove) the oil in the sleeve prior to the replacement of the sleeve. It is conceivable to use air in order to purge the oil. That is, air may be supplied into the flow path, and the oil may be discharged to the outside by the pressure of the air.

When the oil is purged using air, however, the oil may be oxidized by the air. When the oil oxidation progresses, the quality of the oil deteriorates, and the oil cannot be reused.

Thus, the present specification discloses a die-casting machine capable of efficiently purging oil from a sleeve while suppressing deterioration in the quality of the oil.

An aspect of the present specification provides a die-casting machine including:

In this case, the die-casting machine may further include

Further, the controller may store a predetermined purge time in advance, and continue supply of the inert gas by way of the purge line for a purge time.

According to the feature disclosed in the present specification, it is possible to efficiently purge the oil from the sleeve while suppressing deterioration in the quality of the oil.

Hereinafter, the configuration of the die-casting machinewill be described with reference to the drawings.is a diagram illustrating a configuration of a die-casting machine. The die-casting machineis an apparatus for manufacturing a molded product made of a metal such as aluminum, for example, an automobile component. The die-casting machinemay be used, for example, in a method called mega-casting or giga-casting in which large-sized components are integrally formed by die-casting.

The die-casting machineincludes a mold clamping device, an injection device, an extrusion device, and a temperature control device. The mold clamping deviceincludes a fixing plate, a movable platen, and a tie bar. Each of the fixing plateand the movable platenis a base member to which a mold is attached. A distal end portion of the tie baris fixed to the fixing plate. The movable platenis disposed so as to face the fixing plate. The movable platenis moved along the tie barby a driving device (not shown).

A fixed moldis attached to the fixing plate, and a movable moldis attached to the movable platen. The movable moldis formed with a through hole through which an extrusion pinto be described later is inserted. The mold clamping devicemoves the movable moldtogether with the movable platento open and close the mold,. By closing the mold,, a cavity or cavityhaving a shape corresponding to the product shape is formed between the movable moldand the fixed mold. This cavityis filled with molten metalwhich is a molten material.

As shown in, a suction holeis formed in the fixing plate, and the cavityis communicated with a vacuum source (not shown) via the suction hole. Typically, prior to filling the cavitywith the molten metal, the cavityis evacuated. Then, when the cavitybecomes negative pressure, the molten metalis reliably guided to the corner portion of the cavity.

The injection devicehas a sleeveand a plunger. The sleeveis a cylindrical member. One end of the sleeveis fixed to the fixing plate, and the sleevecommunicates with the cavity. During casting, the molten metalis supplied to the sleevethrough the inletand injected into the cavitythrough the sleeve.

A plungeris inserted into the other end of the sleeve. When the plungeris advanced inside the sleeve, the molten metalin the sleeveis injected into the cavity. The plungerapplies a high pressure to the molten metalin order to spread the molten metalto the corner of the cavity. As a result, a large pressure load is applied to the sleeve.

The extrusion devicehas an extrusion pinand an extrusion plate. The extrusion pinis inserted into a through hole of the movable mold. Further, the proximal end of the extrusion pinis fixed to the extrusion plate, and the extrusion pinadvances and retreats along the through hole together with the extrusion plate. The extrusion plateis moved relative to the movable moldby a driving device (not shown). When the mold,is opened by the mold clamping device, the extrusion pinprotrudes toward the fixed mold. As a result, the die-cast product is released from the movable mold.

The temperature control deviceadjusts the temperature of the sleeve. That is, as described above, the molten metalis pumped from the sleeveto the cavity. When the temperature of the molten metaldecreases, the viscosity of the molten metaldecreases, and the molten metalhardly spreads to the corner of the cavity. Therefore, the molten metalneeds to be injected into the cavityfrom the sleevewhile maintaining a high temperature.

However, with the increase in the size of the die-cast product, the amount of molten metal handled in one injection process increases. In this case, the time required for one injection is increased, and the temperature of the molten metalmay decrease before the injection is completed. In particular, in the die-casting method of large parts called mega-cast or giga-cast, a large amount of molten metalis supplied to the sleeveeach time one injection is performed. In order to suppress the temperature drop of the molten metalin the sleeveuntil the injection of the large amount of the molten metalis completed, a temperature control deviceis provided.

The temperature control deviceincludes an oil flow path, an oil tank, and a controller. The oil flow pathis a flow path through which oil for temperature control flows, and is a flow path formed in the sleeve. By flowing the heated temperature control oil into the oil flow path, the temperature of the sleeveand thus the molten metalin the sleeveis effectively prevented from decreasing.

The oil flow pathis connected to the inlet linevia the introduction port, and is connected to the outlet linevia the outlet port. Both the inlet lineand the outlet lineare connected to the oil tank.

The oil tankis a container for storing oil for temperature control. The configuration of the oil tankis not particularly limited as long as it can store a sufficient amount of oil. For example, the oil tankmay be a closed container that blocks the stored oil from the outside air in order to suppress oxidation of the temperature control oil.

The oil tankis further provided with a heaterand a pump. The heaterheats the temperature control oil stored in the oil tank. The pumppumps the temperature control oil stored in the oil tankto the inlet line. When the pumpis driven, the temperature control oil is circulated between the oil flow pathand the oil tank.

The controllercontrols driving of the above-described pumpand heater. The controlleris physically a computer having a processorand a memory. The controllercontrols the driving of the pumpand the heateraccording to the progress of the die casting and the temperature of the temperature control oil or sleevedetected by a temperature sensor (not shown). In addition to controlling the pumpand the heater, the controllermay further control driving of at least one of the movable platen, the extrusion plate, and the plunger. In any case, by providing the above-described temperature control deviceand flowing the heated temperature control oil through the sleeve, the temperature drop of the molten metalis suppressed, and the quality drop of the die-cast product can be suppressed.

Incidentally, as described above, the sleeveis subjected to a high-temperature and high-pressure load at each injection. Repeated application of such loads results in gradual degradation of the sleeve. Therefore, the sleeveis replaced periodically or irregularly depending on the deterioration situation. When the temperature control oil remains in the sleeveduring the replacement, the temperature control oil leaks to the outside. These leaking oils reduce the workability of the change and contaminate the periphery of the die-casting machine.

Therefore, it is conceivable to purge the temperature control oil from the oil flow pathprior to the replacement of the sleeve. For this purge, it is conceivable to send compressed air to the oil flow path. In this case, the temperature control oil is pushed out by compressed air and purged from the sleeve. However, when compressed air is used, oxidation of the temperature control oil proceeds. When the quality of the temperature control oil is significantly reduced by the oxidation, the temperature control oil cannot be reused after the replacement of the sleeveis completed.

Therefore, in the present example, the temperature control oil is purged with an inert gas instead of air. To enable purging with an inert gas, the die-casting machinefurther includes a gas sourceand a purge line. The gas sourceis a source of an inert gas. The inert gas is a gas that is difficult to react with other elements. The inert gas is, for example, a noble gas such as helium or argon, or a nitrogen gas. The gas sourceis, for example, a gas tank that stores such an inert gas in a high-pressure state, or a gas generator that generates an inert gas.

The purge lineis a line connecting the gas sourceand the inlet line. A switching valveis provided at an intersection of the purge lineand the inlet line. By switching the switching valve, the communication destination of the introduction portis switched to the oil tankor the gas source. Hereinafter, the state of the switching valvein which the introduction portcommunicates with the oil tankis referred to as a “normal state”, and the state of the switching valvein which the introduction portcommunicates with the gas sourceis referred to as a “purge state”. The switching valveis, for example, a solenoid valve that is driven by receiving an electric signal.

When the sleeveis replaced, the switching valveis switched from the normal state to the purge state prior to the replacement operation. The switching of the switching valvemay be performed manually by the user or automatically by the controller. When the switching valveis switched to the purge state, the high-pressure inert gas flows into the oil flow pathvia the inlet lineand the introduction port. Then, the temperature control oil remaining in the oil flow pathis pushed out of the sleeveby the pressure of the inert gas. The extruded temperature control oil is discharged to the oil tankvia the outlet portand the outlet line. In order to adjust the pressure of the inert gas, a booster pump or a pressure regulating valve may be provided in the purge line.

If almost all the temperature control oil can be discharged from the oil flow path, the switching valveis switched from the purge state to the normal state. This switching may also be performed manually by the user or automatically by the controller. For example, the controllermay measure the elapsed time from the start of purging, that is, the elapsed time from the time when the switching valveis switched from the normal state to the purge state, by the timer. The controllermay switch the switching valvefrom the purge state to the normal state at a timing when the measurement time reaches a predetermined purge time. In this case, the purge time is a time period during which the temperature control oil can be discharged from the oil flow path, and is a time period specified in advance by an experiment or a simulation. Such purge time may be an invariant fixed value or may be a variable value that varies according to conditions. For example, the purge time may be changed according to at least one of the air temperature, the oil temperature, the type of the sleeve, and the type of the oil for temperature control. Alternatively, the controllermay monitor the flow rate of the temperature control oil discharged from the oil flow path, and switch the switching valvefrom the purge state to the normal state at a timing when the discharge flow rate becomes substantially zero.

When the temperature control oil is sufficiently purged from the oil flow path, the user removes the sleevefrom the die-casting machineand replaces it with a new sleeve. At this time, since the temperature control oil does not leak from the sleeve, the user can easily perform the replacement work. When the replacement of the sleeveis completed, the oil flow pathof the new sleeveis filled with the recovered temperature control oil. Here, the temperature control oil recovered in the purge process is recovered without touching the air. Therefore, oxidation of the temperature control oil does not proceed during the purge process, and quality deterioration of the temperature control oil can be effectively prevented. Thus, after the sleeveis replaced, the discharged temperature control oil can be refilled into the oil flow pathof the new sleeve. As a result, the amount of waste of the temperature control oil can be reduced, the cost can be reduced, or the load on the environment can also be reduced.

Note that the gas sourcemay be provided exclusively for oil purging, or the gas sourceused in other applications may be used for purging. For example, in the die-casting machine, an inert gas is often supplied to the oil surface of the molten metalin order to suppress an oxide film being formed on the oil surface of the molten metal. A gas source (hereinafter referred to as a “main gas source”) prepared for preventing the oxidation of the molten metal may be used as the gas sourcefor oil purging.

is a diagram illustrating a configuration of a die-casting machinethat uses a main gas source as a purge gas source. As shown in, the die-casting machinefurther includes a gas linethat communicates the gas sourcewith the inlet. A second switching valveis provided at an intersection of the gas lineand the purge line. The controllerswitches the second switching valveso that the gas sourceand the inletcommunicate with each other during the die casting process. On the other hand, during a period in which the temperature control oil is purged from the oil flow path, the controllerswitches the second switching valveso that the gas sourceand the inlet linecommunicate with each other.

Here, the main gas source does not need a period during which the die casting process is not performed. Since the replacement of the sleeveis performed during the period in which the die casting process is not performed, the main gas source is always available as the purge gas sourceduring the period in which the replacement of the sleeveis performed. As described above, by performing purging using an existing gas source, additional equipment is unnecessary, and the oil purging can be performed at a lower cost.

Note that any of the configurations described above is an example, and other configurations may be changed as appropriate as long as the configuration described in claimis provided.