JP2014113638A - Casting device and casting method - Google Patents

Abstract

The present invention provides a casting apparatus and a casting method capable of shortening manufacturing time without deteriorating product quality.
A casting apparatus includes a displacement meter and a control unit. The displacement meter detects the displacement of the molten metal surface in the pressurizing chamber. The control unit detects that the filling of the molten metal into the cavity is completed based on the output of the displacement meter while supplying the pressurized gas to the pressurized chamber in the step of supplying the molten metal to the cavity. Further, the control unit controls the gas supply means so as to maintain the pressure of the pressurized gas constant for a predetermined time in the process of pressurizing and cooling the molten metal.
[Selection] Figure 2

Description

  The present invention relates to a casting apparatus and a casting method used for low-pressure casting or low-medium pressure casting.

  2. Description of the Related Art Conventionally, a casting apparatus for manufacturing an aluminum composite product such as an aluminum wheel by low pressure casting or low / medium pressure casting is known. In this type of casting apparatus, the pressure in the pressurizing chamber is increased while the molten metal is accommodated in the pressurizing chamber (crucible), and the molten metal is filled into the mold cavity from the pressurizing chamber via the stalk by this pressure. Subsequently, while maintaining a predetermined pressure state, the molten metal is solidified in the cavity to cast a cast product. Finally, the mold is opened and the cast product is taken out.

  In the conventional casting apparatus described above, the molten metal for the cavity of the mold decreases from the pressurizing chamber for each casting stroke, so the level of the hot water in the pressurizing chamber gradually decreases, and pressure fluctuation occurs. As a result, there is a problem that defective filling of the molten metal into the cavity occurs.

  Then, if it detects that the molten metal was filled in the cavity, the technique which eliminated the casting defect produced by the molten metal surface state by correct | amending a reference | standard pressurization pattern is known (patent document 1). . In addition, a technique is also known in which the level of the molten metal is always kept constant in the initial state of the casting cycle by raising and lowering the crucible according to the level of the molten metal in the pressurizing chamber (Patent Document 2). . Further, the holding chamber for holding the molten metal, the pressurizing chamber, and the stalk that communicates with the mold cavity are separated and communicated with each other, and a shutoff valve is provided in the communication path that connects the holding chamber and the pressurizing chamber. There is also known a technique in which a casting defect is eliminated by always providing a constant molten metal in a pressurizing chamber in an initial state of a casting cycle (Patent Document 3).

JP-A-7-303955 JP-A-6-320250 JP-A-11-138250

  However, in the technique disclosed in the cited document 1, since the molten metal surface level is not always constant in the initial state of the casting cycle, it is difficult to completely eliminate casting defects by correcting the pressure pattern. Moreover, in the cited documents 2 and 3, the melt level in the pressurizing chamber is monitored, but this is used to keep the melt level before pressurization constant, from the start of pressurization to the completion of filling. It is not possible to control the fine pressure pattern. For this reason, the cavity cannot be efficiently filled, resulting in problems such as deterioration of product quality and a long filling time.

  This invention is made | formed in view of the said situation, and it aims at providing the casting apparatus and casting method which can aim at shortening of manufacturing time, without deteriorating the quality of a product.

  A casting apparatus according to the present invention includes a holding chamber for holding a molten metal, a molten metal supplied from the holding chamber in communication with the holding chamber through a first communication path, and forming a sealed space on the upper surface of the molten metal. A pressurizing chamber that communicates with the pressurizing chamber via the second communication passage, a stalk whose upper end opening communicates with the opening of the cavity of the mold, and from the holding chamber to the pressurizing chamber at the start of a casting cycle. A molten metal supply means for supplying the molten metal at a preset molten metal level, a gas supply means for supplying pressurized gas to the sealed space of the pressurized chamber, and displacement of the molten metal surface of the molten metal in the pressurized chamber. In the step of detecting the displacement meter and supplying the molten metal to the cavity, the filling of the molten metal into the cavity is detected based on the output of the displacement meter while supplying the pressurized gas to the pressure chamber. Pressurize and cool the molten metal Characterized in that it comprises a control unit for controlling the gas supply means to maintain the pressure of the pressurized gas to a predetermined time constant in the step of.

  In the casting method according to the present invention, the molten metal is supplied from the holding chamber holding the molten metal to the pressurizing chamber, and the molten metal is filled from the pressurizing chamber to the stalk by increasing the pressure of the pressurizing chamber. In a casting method for filling the mold cavity with the molten metal, a step of supplying the molten metal at a preset level from the holding chamber to the pressure chamber at the start of a casting cycle; The step of filling the cavity with the molten metal by detecting the level of the molten metal level with a displacement meter and increasing the pressure of the pressurizing chamber based on the output of the displacement meter, and the pressure of the molten metal filled in the cavity And maintaining the temperature constant for a predetermined time.

  According to the present invention, in the step of supplying molten metal to the cavity, the pressure in the pressurizing chamber is controlled by grasping the state of filling of the melt into the cavity based on the output of a displacement meter that detects displacement of the molten metal surface in the pressurizing chamber. Therefore, the manufacturing time can be shortened without deteriorating the quality of the product.

It is the schematic which shows the casting apparatus which concerns on embodiment. It is a flow chart of pressure control concerning an embodiment. It is a figure which shows the state of the hot_water | molten_metal surface in each time which concerns on embodiment. It is a change pattern of the pressure and hot water level which concern on embodiment. It is the schematic which shows the casting apparatus which concerns on other embodiment.

  Hereinafter, a casting apparatus and a casting method according to embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing a casting apparatus according to the embodiment. The casting apparatus according to the present embodiment is mainly used for low-pressure casting that applies a pressure of less than 0.2 MPa. As shown in FIG. 1, the casting apparatus includes a holding chamber 20 that holds the molten metal 10, and a holding chamber 20 that is connected to the holding chamber 20 via the first communication passage 70 and holds the molten metal 10 supplied from the holding chamber 20. The pressure chamber 30 and the stalk 40 communicated with the pressure chamber 30 via the second communication path 80 are provided. The upper end of the stalk 40 is connected to the opening of the fixed mold 51 communicating with the cavity 53 of the mold 50 including the fixed mold 51 and the movable mold 52, and supplies the molten metal 10 to the cavity 53. In the holding chamber 20, the first communication path 70, and the second communication path 80, heaters 21, 71, 81 for heating the molten metal 10 to temperatures necessary to maintain a molten state of about 500 ° C. to 700 ° C., respectively. Is provided.

  The holding chamber 20 is provided with a stopper 22 that controls the supply of the molten metal 10 to the pressurizing chamber 30. The stopper 22 is connected to the first communication passage 70 of the holding chamber 20 based on the control of the control unit 60 described later so that the constant molten metal 10 is always accommodated in the pressurizing chamber 30 in the initial state of the casting process. Open and close the entrance.

  The upper end opening of the pressurizing chamber 30 is closed by the lid 34, and the upper surface space of the molten metal 10 in the pressurizing chamber 30 becomes a sealed space. A gas supply unit 90 is connected to the sealed space via the gas inlet 31. The gas supply unit 90 supplies an inert gas into the pressurizing chamber 30 through the gas inlet 31. The lid 34 is provided with a hot water level detection rod 32 facing the liquid surface of the molten metal 10. When the molten metal 10 is sent from the holding chamber 20 to the pressurizing chamber 30, the molten metal level detection rod 32 detects whether or not the molten metal level of the molten metal 10 in the pressurizing chamber 30 has reached a predetermined level. In addition, a displacement meter 33 is installed on the top of the lid 34. The displacement meter 33 detects the displacement of the molten metal level in the pressurizing chamber 30 at the molten metal level. The displacement meter 33 is, for example, a laser sensor, an ultrasonic sensor, a float sensor, or the like.

  The control unit 60 controls opening and closing of the stopper 22 based on the detection output from the molten metal level detection rod 32 and based on the displacement of the molten metal level detected by the displacement meter 33 when the molten metal 10 is supplied to the cavity 53. The amount of the inert gas supplied from the gas inlet 31 is adjusted. Thereby, the control unit 60 controls the pressure in the pressurizing chamber 30. For example, the control unit 60 is configured by a computer. The control unit 60 stores in advance information such as known parameters necessary for pressure control by displacement of the molten metal surface, that is, the cross-sectional area of the pressurizing chamber 30, the volume of the stalk 40, and the volume of the cavity 53. A storage unit 61 is provided.

  Next, with reference to FIG. 2 to FIG. 4, the relationship between the displacement of the molten metal surface in the pressurizing chamber 30 and the pressure in the pressurizing chamber 30 when the molten metal 10 is filled in the cavity 53 will be described. . FIG. 2 is a flow chart of pressure control, FIG. 3 shows the state of the molten metal surface at each time point, and FIG. 4 shows the change pattern of the pressure and the molten metal surface level. As shown in FIG. 4, the casting process includes a first process that is a stalk filling process, a second process that is a cavity filling process, and a third process that is a pressure / cooling process. The first step and the second step are steps for controlling at the level of the molten metal, and the third step is a step for controlling at the elapsed time (time level).

[Control process at hot water level]
First, the controller 60 sets the pressure increase rate to V1 (S1), and gradually increases the pressure in the pressurizing chamber 30 from the atmospheric pressure from the initial state shown in FIG. 3A (time t0 in FIG. 4). To go. Next, as in the state shown in FIG. 3B (time t1 in FIG. 4), it is determined whether or not the molten metal 10 is filled up to just before the cavity 53 (S2). That is, in step S2, it is determined whether or not the filling of the molten metal 10 into the stalk 40 is completed. The determination in step S2 is made based on the cross-sectional area of the pressurizing chamber 30 and the capacity of the stalk 40 stored in the storage unit 61 in advance, and the output of the displacement meter 33 that detects the displacement of the molten metal surface in the pressurizing chamber 30. The That is, when the filling of the molten metal 10 into the stalk 40 is completed, as shown at time t1 in FIG. 3B and FIG. 4, the molten metal surface of the molten metal 10 in the pressurizing chamber 30 is lowered from the initial level L0 to the level L1. . Therefore, it is determined whether or not the product of the cross-sectional area of the pressurizing chamber 30 and the amount L1-L0 of the molten metal surface matches the known volume of the stalk 40.

  If it is determined in step S2 that the filling of the molten metal 10 into the stalk 40 is not completed (S2, No), step S2 is repeatedly executed. On the other hand, when it is determined that the filling of the molten metal 10 into the stalk 40 is completed (S2, Yes), the control unit 60 sets the pressure increase rate to V2 (V2 <V1) (S3), and FIG. From the state shown in FIG. 4 (time t1 in FIG. 4), the pressure in the pressurizing chamber 30 is gradually increased. Subsequently, it is determined whether or not the molten metal 10 is filled to α% of the cavity 53 as in the state shown in FIG. 3C (time t2 in FIG. 4) (S4). The determination in step S4 is made based on the capacity information of the cavity 53 and the output of the displacement meter 33 that detects the displacement of the hot water surface of the pressurizing chamber 30. That is, if the molten metal 10 is filled up to α% of the cavity 53, the molten metal surface of the molten metal 10 in the pressurizing chamber 30 is from level L1 to level L2, as shown at time t2 in FIG. Go down. Therefore, it is determined whether or not the product of the cross-sectional area of the pressurizing chamber 30 and the amount of change L2-L1 of the molten metal matches the α volume of the known cavity 53.

  If it is determined in step S4 that the molten metal 10 is not filled up to α% of the cavity 53 (S4, No), step S4 is repeatedly executed. On the other hand, if it is determined that the molten metal 10 is filled to α% of the cavity 53 (S4, Yes), the control unit 60 sets the pressure increase rate to V3 (V3> V2) (S5), and FIG. From the state shown in FIG. 4 (time t2 in FIG. 4), the pressure in the pressurizing chamber 30 is gradually increased. Subsequently, it is determined whether or not the filling of the molten metal 10 into the cavity 53 is completed as shown in FIG. 3D (time t3 in FIG. 4) (S6). The determination in step S6 is made based on the information on the capacity of the cavity 53, and the output of the displacement meter 33 that detects the displacement of the pressurizing chamber 30 and the displacement of the molten metal surface. That is, when the filling of the cavity 53 is completed, the molten metal surface of the molten metal 10 in the pressurizing chamber 30 is lowered from the level L2 to the level L3 as shown at time t3 in FIG. Therefore, it is determined whether or not the product of the cross-sectional area of the pressurizing chamber 30 and the amount L3-L1 of the molten metal surface matches the known volume of the cavity 53.

  If it is determined in step S6 that the filling of the molten metal 10 into the cavity 53 has not been completed (S6, No), step S6 is repeatedly executed. On the other hand, when it is determined that the filling of the molten metal 10 into the cavity 53 is completed (S6, Yes), the control proceeds to the time level control.

[Time level control process]
In the time level control, the pressure in the pressurizing chamber 30 is maintained at a predetermined pressure (S7). Subsequently, the control unit 60 determines whether or not a predetermined time has elapsed since the start of holding the pressure in the pressurizing chamber 30 (S8).

  If it is determined in step S8 that the predetermined time has not elapsed (S8, No), step S8 is repeatedly executed. On the other hand, when it is determined that the predetermined time has elapsed (S8, Yes), the control unit 60 opens the pressurizing chamber 30 to the atmosphere as shown at time t4 in FIG. 4 (S9). Subsequently, the control unit 60 opens the mold (S10), and the cast product is taken out.

  As described above, the present embodiment grasps the filling state of the molten metal 10 into the cavity 53 based on the output of the displacement meter 33 that detects the displacement of the molten metal surface in the pressurizing chamber 30 in the step of supplying the molten metal 10 to the cavity 53. Thus, the pressure in the pressurizing chamber 30 is controlled. Therefore, this embodiment can shorten the manufacturing time without deteriorating the quality of the product.

  Although the embodiments of the invention have been described above, the present invention is not limited to these embodiments, and various modifications and additions can be made without departing from the spirit of the invention. For example, as shown in FIG. 5, a cylindrical sleeve 35 may be provided along the side surface in the pressurizing chamber 30. In this case, the cross-sectional area of the pressurizing chamber 30 decreases as the thickness of the sleeve 35 increases, so that the displacement of the molten metal surface of the molten metal 10 increases. Thereby, there exists an advantage that finer level control of the hot water level than the previous embodiment is attained.

  DESCRIPTION OF SYMBOLS 10 ... Molten metal, 20 ... Holding chamber, 30 ... Pressurizing chamber, 40 ... Stoke, 50 ... Mold, 60 ... Control part, 70 ... 1st communicating path, 80 ... 2nd communicating path.

Claims (3)

A holding chamber for holding molten metal;
A pressurizing chamber that communicates with the holding chamber via a first communication path and that contains the molten metal supplied from the holding chamber and forms a sealed space on the upper surface of the molten metal;
Stoke in which the upper end opening communicates with the pressurizing chamber via the second communication passage and communicates with the opening of the mold cavity;
A molten metal supply means for supplying the molten metal at a molten metal level set in advance from the holding chamber to the pressurizing chamber at the start of a casting cycle;
Gas supply means for supplying a pressurized gas to the sealed space of the pressurizing chamber;
A displacement meter for detecting displacement of the molten metal surface in the pressurized chamber;
In the step of supplying the molten metal to the cavity, it is detected that the filling of the molten metal into the cavity is completed based on the output of the displacement meter while supplying the pressurized gas to the pressurized chamber, and the molten metal is added. And a controller for controlling the gas supply means so as to maintain the pressure of the pressurized gas constant for a predetermined time in the pressure / cooling step. The controller is configured to fill the stalk with the molten metal based on an output of the displacement meter, to fill the molten metal up to α% of the total capacity of the cavity, and to completely fill the cavity with the molten metal. 2. The casting apparatus according to claim 1, wherein a filling speed of the pressure applied to the pressurizing chamber is controlled by detecting the filling of the pressure chamber. The molten metal is supplied from the holding chamber holding the molten metal to the pressurizing chamber, and the molten metal is filled into the stalk from the pressurizing chamber by increasing the pressure of the pressurizing chamber. In the casting method of filling,
Supplying the molten metal at a preset level from the holding chamber to the pressurizing chamber at the start of a casting cycle;
Filling the cavity with the molten metal by detecting the level of the hot water level in the pressurizing chamber with a displacement meter and increasing the pressure in the pressurizing chamber based on the output of the displacement meter;
And a step of maintaining the pressure of the molten metal filled in the cavity constant for a predetermined time.

Images