DIE-CASTING MACHINE

Abstract

The die-casting machine comprises a sleeve in which an oil flow path has been formed. an oil tank, an inlet line, an outlet line, a purge line, and a controller to discharge the oil from the sleeve by sending the inert gas from the purge line to the oil flow path prior to replacement of the sleeve.

Claims

1. A die-casting machine comprising: a sleeve in which an oil flow path is provided; an oil tank that stores oil; an inlet line that leads the oil output from the oil tank to the oil flow path; an outlet line that leads the oil output from the oil flow path to the oil tank; a purge line that merges with the inlet line and leads an inert gas to the oil flow path by way of the inlet line; and a controller that discharges the oil from the sleeve by sending the inert gas from the purge line to the oil flow path prior to replacement of the sleeve.

2. The die-casting machine according to claim 1, further comprising: a gas source that stores or generates the inert gas; and a gas line that leads the inert gas to molten metal, wherein the controller switches a communication destination of the gas source to the purge line or the gas line.

3. The die-casting machine according to claim 1, wherein the controller stores a predetermined purge time in advance, and continues supply of the inert gas by way of the purge line for a purge time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] FIG. 1 is a diagram showing a configuration of a die-casting machine; and

[0024] FIG. 2 is a diagram illustrating another configuration of a die-casting machine.

DETAILED DESCRIPTION OF EMBODIMENTS

[0025] 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 die-casting machine 10. The die-casting machine 10 is an apparatus for manufacturing a molded product made of a metal such as aluminum, for example, an automobile component. The die-casting machine 10 may be used, for example, in a method called mega-casting or giga-casting in which large-sized components are integrally formed by die-casting.

[0026] The die-casting machine 10 includes a mold clamping device 12, an injection device 20, an extrusion device 26, and a temperature control device 50. The mold clamping device 12 includes a fixing plate 14, a movable platen 16, and a tie bar 18. Each of the fixing plate 14 and the movable platen 16 is a base member to which a mold is attached. A distal end portion of the tie bar 18 is fixed to the fixing plate 14. The movable platen 16 is disposed so as to face the fixing plate 14. The movable platen 16 is moved along the tie bar 18 by a driving device (not shown).

[0027] A fixed mold 102 is attached to the fixing plate 14, and a movable mold 100 is attached to the movable platen 16. The movable mold 100 is formed with a through hole through which an extrusion pin 28 to be described later is inserted. The mold clamping device 12 moves the movable mold 100 together with the movable platen 16 to open and close the mold 100,102. By closing the mold 100,102, a cavity or cavity 34 having a shape corresponding to the product shape is formed between the movable mold 100 and the fixed mold 102. This cavity 34 is filled with molten metal 110 which is a molten material.

[0028] As shown in FIG. 1, a suction hole 32 is formed in the fixing plate 14, and the cavity 34 is communicated with a vacuum source (not shown) via the suction hole 32. Typically, prior to filling the cavity 34 with the molten metal 110, the cavity 34 is evacuated. Then, when the cavity 34 becomes negative pressure, the molten metal 110 is reliably guided to the corner portion of the cavity 34.

[0029] The injection device 20 has a sleeve 22 and a plunger 24. The sleeve 22 is a cylindrical member. One end of the sleeve 22 is fixed to the fixing plate 14, and the sleeve 22 communicates with the cavity 34. During casting, the molten metal 110 is supplied to the sleeve 22 through the inlet 38 and injected into the cavity 34 through the sleeve 22.

[0030] A plunger 24 is inserted into the other end of the sleeve 22. When the plunger 24 is advanced inside the sleeve 22, the molten metal 110 in the sleeve 22 is injected into the cavity 34. The plunger 24 applies a high pressure to the molten metal 110 in order to spread the molten metal 110 to the corner of the cavity 34. As a result, a large pressure load is applied to the sleeve 22.

[0031] The extrusion device 26 has an extrusion pin 28 and an extrusion plate 30. The extrusion pin 28 is inserted into a through hole of the movable mold 100. Further, the proximal end of the extrusion pin 28 is fixed to the extrusion plate 30, and the extrusion pin 28 advances and retreats along the through hole together with the extrusion plate 30. The extrusion plate 30 is moved relative to the movable mold 100 by a driving device (not shown). When the mold 100,102 is opened by the mold clamping device 12, the extrusion pin 28 protrudes toward the fixed mold 102. As a result, the die-cast product is released from the movable mold 100.

[0032] The temperature control device 50 adjusts the temperature of the sleeve 22. That is, as described above, the molten metal 110 is pumped from the sleeve 22 to the cavity 34. When the temperature of the molten metal 110 decreases, the viscosity of the molten metal 110 decreases, and the molten metal 110 hardly spreads to the corner of the cavity 34. Therefore, the molten metal 110 needs to be injected into the cavity 34 from the sleeve 22 while maintaining a high temperature.

[0033] 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 metal 110 may 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 metal 110 is supplied to the sleeve 22 each time one injection is performed. In order to suppress the temperature drop of the molten metal 110 in the sleeve 22 until the injection of the large amount of the molten metal 110 is completed, a temperature control device 50 is provided.

[0034] The temperature control device 50 includes an oil flow path 40, an oil tank 52, and a controller 58. The oil flow path 40 is a flow path through which oil for temperature control flows, and is a flow path formed in the sleeve 22. By flowing the heated temperature control oil into the oil flow path 40, the temperature of the sleeve 22 and thus the molten metal 110 in the sleeve 22 is effectively prevented from decreasing.

[0035] The oil flow path 40 is connected to the inlet line 46 via the introduction port 42, and is connected to the outlet line 48 via the outlet port 44. Both the inlet line 46 and the outlet line 48 are connected to the oil tank 52.

[0036] The oil tank 52 is a container for storing oil for temperature control. The configuration of the oil tank 52 is not particularly limited as long as it can store a sufficient amount of oil. For example, the oil tank 52 may be a closed container that blocks the stored oil from the outside air in order to suppress oxidation of the temperature control oil.

[0037] The oil tank 52 is further provided with a heater 56 and a pump 54. The heater 56 heats the temperature control oil stored in the oil tank 52. The pump 54 pumps the temperature control oil stored in the oil tank 52 to the inlet line 46. When the pump 54 is driven, the temperature control oil is circulated between the oil flow path 40 and the oil tank 52.

[0038] The controller 58 controls driving of the above-described pump 54 and heater 56. The controller 58 is physically a computer having a processor 60 and a memory 62. The controller 58 controls the driving of the pump 54 and the heater 56 according to the progress of the die casting and the temperature of the temperature control oil or sleeve 22 detected by a temperature sensor (not shown). In addition to controlling the pump 54 and the heater 56, the controller 58 may further control driving of at least one of the movable platen 16, the extrusion plate 30, and the plunger 24. In any case, by providing the above-described temperature control device 50 and flowing the heated temperature control oil through the sleeve 22, the temperature drop of the molten metal 110 is suppressed, and the quality drop of the die-cast product can be suppressed.

[0039] Incidentally, as described above, the sleeve 22 is subjected to a high-temperature and high-pressure load at each injection. Repeated application of such loads results in gradual degradation of the sleeve 22. Therefore, the sleeve 22 is replaced periodically or irregularly depending on the deterioration situation. When the temperature control oil remains in the sleeve 22 during 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 10.

[0040] Therefore, it is conceivable to purge the temperature control oil from the oil flow path 40 prior to the replacement of the sleeve 22. For this purge, it is conceivable to send compressed air to the oil flow path 40. In this case, the temperature control oil is pushed out by compressed air and purged from the sleeve 22. 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 sleeve 22 is completed.

[0041] 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 machine 10 further includes a gas source 74 and a purge line 70. The gas source 74 is 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 source 74 is, 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.

[0042] The purge line 70 is a line connecting the gas source 74 and the inlet line 46. A switching valve 72 is provided at an intersection of the purge line 70 and the inlet line 46. By switching the switching valve 72, the communication destination of the introduction port 42 is switched to the oil tank 52 or the gas source 74. Hereinafter, the state of the switching valve 72 in which the introduction port 42 communicates with the oil tank 52 is referred to as a normal state, and the state of the switching valve 72 in which the introduction port 42 communicates with the gas source 74 is referred to as a purge state. The switching valve 72 is, for example, a solenoid valve that is driven by receiving an electric signal.

[0043] When the sleeve 22 is replaced, the switching valve 72 is switched from the normal state to the purge state prior to the replacement operation. The switching of the switching valve 72 may be performed manually by the user or automatically by the controller 58. When the switching valve 72 is switched to the purge state, the high-pressure inert gas flows into the oil flow path 40 via the inlet line 46 and the introduction port 42. Then, the temperature control oil remaining in the oil flow path 40 is pushed out of the sleeve 22 by the pressure of the inert gas. The extruded temperature control oil is discharged to the oil tank 52 via the outlet port 44 and the outlet line 48. 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 70.

[0044] If almost all the temperature control oil can be discharged from the oil flow path 40, the switching valve 72 is switched from the purge state to the normal state. This switching may also be performed manually by the user or automatically by the controller 58. For example, the controller 58 may measure the elapsed time from the start of purging, that is, the elapsed time from the time when the switching valve 72 is switched from the normal state to the purge state, by the timer 64. The controller 58 may switch the switching valve 72 from 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 40, 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 22, and the type of the oil for temperature control. Alternatively, the controller 58 may monitor the flow rate of the temperature control oil discharged from the oil flow path 40, and switch the switching valve 72 from the purge state to the normal state at a timing when the discharge flow rate becomes substantially zero.

[0045] When the temperature control oil is sufficiently purged from the oil flow path 40, the user removes the sleeve 22 from the die-casting machine 10 and replaces it with a new sleeve 22. At this time, since the temperature control oil does not leak from the sleeve 22, the user can easily perform the replacement work. When the replacement of the sleeve 22 is completed, the oil flow path 40 of the new sleeve 22 is 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 sleeve 22 is replaced, the discharged temperature control oil can be refilled into the oil flow path 40 of the new sleeve 22. 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.

[0046] Note that the gas source 74 may be provided exclusively for oil purging, or the gas source 74 used in other applications may be used for purging. For example, in the die-casting machine 10, an inert gas is often supplied to the oil surface of the molten metal 110 in order to suppress an oxide film being formed on the oil surface of the molten metal 110. 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 source 74 for oil purging.

[0047] FIG. 2 is a diagram illustrating a configuration of a die-casting machine 10 that uses a main gas source as a purge gas source 74. As shown in FIG. 2, the die-casting machine 10 further includes a gas line 76 that communicates the gas source 74 with the inlet 38. A second switching valve 78 is provided at an intersection of the gas line 76 and the purge line 70. The controller 58 switches the second switching valve 78 so that the gas source 74 and the inlet 38 communicate 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 40, the controller 58 switches the second switching valve 78 so that the gas source 74 and the inlet line 46 communicate with each other.

[0048] Here, the main gas source does not need a period during which the die casting process is not performed. Since the replacement of the sleeve 22 is performed during the period in which the die casting process is not performed, the main gas source is always available as the purge gas source 74 during the period in which the replacement of the sleeve 22 is 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.

[0049] 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 claim 1 is provided.