JP5920189B2 - Casting apparatus and casting method - Google Patents

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 metal product. Finally, the mold is opened and the cast product is taken out.

  For example, in the casting apparatus disclosed in Patent Document 1, prior to the casting process described above, a pressurized gas is introduced into the upper portion of the stalk, and the molten metal in the stalk is pushed out into one end of the pressurized chamber, thereby containing the particles. After being stirred, it is introduced again into the stalk (Patent Document 1). In such a casting apparatus, regardless of whether or not the pressurized gas is introduced into the stalk at the start of casting, air is drawn into the stalk at a time when the mold is opened. For this reason, there is a problem that the gas content in the molten metal increases, and gas holes and shrinkage occur in the cast product. Further, there is a problem that an oxide film is formed on the inner surface of the stalk, and this oxide film is taken into the cast product and the quality of the cast product is deteriorated.

  Therefore, by slightly increasing the pressure in the pressurization chamber before opening the mold so that the molten metal level in the stalk does not drop too much when the mold is opened, the amount of air trapped in the stalk is suppressed. A casting apparatus configured to do this is also known (Patent Document 2). However, even in this casting apparatus, there is no change in drawing air into the stalk at the time of mold opening. Further, if the molten metal is left on the upper part of the stalk, there is a problem that the temperature of the molten metal is lowered, the fluidity of the molten metal introduced into the cavity is lowered, and the quality of the cast product is lowered.

JP 2003-275857 A JP-A-5-131261

  The present invention has been made in view of the above circumstances, and provides a casting apparatus and a casting method capable of preventing air from being entrained in the stalk when the mold is opened and improving the quality of the cast product. Objective.

  A casting apparatus according to the present invention includes a mold that forms a cavity having an opening below, a pressurizing chamber that is disposed below the mold and that accommodates the molten metal and forms a sealed space above the molten metal, and an upper end A valve mechanism in which an opening communicates with the opening of the cavity and a lower end opening is immersed in the molten metal in the pressurizing chamber, and a distal end opening / closing portion that opens and closes a gas passage faces the vicinity of the stalk upper portion of the cavity First gas supply means for supplying a first gas to the sealed space of the pressurizing chamber; and second gas supply means for supplying a second gas to the vicinity of the upper portion of the stalk of the cavity via the valve mechanism. And controlling the first and second gas supply means to introduce the first gas into the pressurizing chamber and open the second gas to the stalk of the cavity prior to the mold opening operation of the mold. Introduced near the top And a control device that lowers the molten metal level in the stalk to a level of the molten metal level in the pressurizing chamber while gradually decreasing the gas pressure of the first gas and the second gas. To do.

  The casting method according to the present invention also includes a mold cavity through a stalk whose lower end is immersed in the molten metal by introducing a first gas into the pressurized chamber containing the molten metal and pressurizing the pressurized chamber. A first step of filling the melt with the molten metal, and introducing the first gas into the pressurizing chamber and introducing the second gas into the vicinity of the upper portion of the stalk of the cavity, and the gas pressures of the first gas and the second gas. A second step of lowering the molten metal level in the stalk to the level of the molten metal level in the pressurizing chamber while gradually lowering the mold, and opening the mold to take out the cast product in the cavity And a third step.

  According to the present invention, when lowering the level of the molten metal in the stalk, the first gas is supplied into the pressurizing chamber, the second gas is supplied into the stalk by the valve mechanism, and the first gas and the second gas are supplied. The molten metal level in the stalk is lowered to the level of the molten metal level in the pressurizing chamber while gradually reducing the gas pressure. For this reason, in this invention, entrainment of the air in Stoke can be suppressed and the quality of a product can be improved.

It is the schematic which shows the casting apparatus which concerns on embodiment. It is an enlarged view of the A section of FIG. FIG. 3 is a B-B ′ sectional view of FIG. 2. It is a figure which shows the other state of the valve mechanism. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 1st Embodiment. It is a figure which shows the change of the pressure A in the Stoke 40, the hot_water | molten_metal surface level B of the molten metal 10 of the Stoke 40, and the pressure C in the pressurization chamber 30. It is a figure which shows the casting method which concerns on 2nd Embodiment which changed the pressure application pattern of 1st Embodiment. It is the schematic which shows the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is the schematic which shows operation | movement of the casting apparatus which concerns on 3rd Embodiment. It is a figure which shows the change of the pressure A in the Stoke 40, the hot_water | molten_metal surface level B of the molten metal 10 of the Stoke 40, and the pressure C in the pressurization chamber 30. It is a figure which shows the casting method which concerns on 4th Embodiment which changed the pressure application pattern of 3rd Embodiment.

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

[First Embodiment]
FIG. 1 is a schematic view showing a casting apparatus according to the first embodiment. The present embodiment shows an example in which the present invention is applied to a low pressure casting method. As shown in FIG. 1, the casting apparatus includes a holding chamber 20 that holds a molten metal 10, and a pressurizing chamber that communicates with the holding chamber 20 via a communication path 21 and stores the molten metal 10 supplied from the holding chamber 20. (Crucible) 30. The holding chamber 20 and the pressurizing chamber 30 are respectively provided with heaters 23 and 24 for heating the molten metal 10 to a temperature necessary to maintain a molten state of about 500 ° C. to 700 ° C.

  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 has an inlet to the communication passage 21 of the holding chamber 20 based on the control of the controller 90 to be described later so that the fixed molten metal 10 is always accommodated in the pressurizing chamber 30 in the initial state of the casting process. Open and close.

  The upper end opening of the pressurizing chamber 30 is closed by the fixing plate 33, and the upper surface space of the molten metal 10 in the pressurizing chamber 30 becomes a sealed space. A gas supply path 31 formed in the fixed plate 33 communicates with the sealed space. The gas supply path 31 supplies an inert gas as the first gas into the pressurizing chamber 30. In addition, a hot water level detection rod 32 is installed on the fixed plate 33 toward the liquid level 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.

  At the center of the fixed plate 33, the upper end of a cylindrical stalk 40 having both ends opened is fixed. The lower end of the stalk 40 is immersed in the molten metal 10 in the pressurizing chamber 30.

  A fixed mold 51 is mounted on the upper surface of the fixed plate 33. A movable mold 52 is mounted on the lower surface of the movable plate 34 configured to be movable upward with respect to the fixed mold 51. The fixed mold 51 and the movable mold 52 form a cavity 50 when the mold is closed. An opening 511 is formed in the gate portion communicating with the cavity 50 at the center portion of the fixed mold 51, and the upper end portion of the stalk 40 is communicated with the opening 511. The opening 511 has a first opening 511A and a second opening 511B provided below the first opening 511A. The second opening 511B is linearly tapered with a larger diameter from the upper end to the lower end. The movable mold 52 is provided with a pin-shaped valve mechanism 60 whose tip faces the upper center of the cavity 50.

  The valve mechanism 60 is inserted into the hole 522 and attached to the movable mold 52 so as to block the hole 522 formed in the center of the movable mold 52. The valve mechanism 60 is configured to be able to supply an inert gas into the stalk 40 from above the opening 511 via the gas supply path 521. 2 is an enlarged view of a portion A shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line B-B 'of FIG. FIG. 4 is a view showing another state of the valve mechanism 60. As shown in FIGS. 1 to 4, the valve mechanism 60 includes a double cylinder having an outer cylinder 61 and a movable pin 62 that is movably accommodated in the outer cylinder 61 and has a tip that advances and retreats from the lower end of the outer cylinder 61. It has a structure. Four vertical grooves 621A are formed, for example, equally in the circumferential direction on the outer periphery of the accommodating portion 621 of the movable pin 62 in the outer cylinder 61. These longitudinal grooves 621A are connected to each other by an annular groove 621B extending in the circumferential direction of the movable pin 62 at the lower end portion thereof. The vertical groove 621A and the annular groove 621B form a gas supply path 621C for an inert gas.

  The movable pin 62 has an upper end connected to a piston mechanism 63 serving as a driving means, and is driven in the vertical direction inside the outer cylinder 61, and a lower end is advanced and retracted from the lower end of the outer cylinder 61. The lower end portion 622 of the movable pin 62 is formed in a downward conical shape, and the base end outer peripheral portion is a valve that closes the inner surface of the lower end opening of the outer cylinder 61 when the movable pin 62 is retracted, as shown in FIG. It has a function. As shown in FIG. 4, when the movable pin 62 protrudes from the lower end of the outer cylinder 61, the valve is opened and the inert gas introduced into the gas supply path 621C is discharged downward.

  The casting apparatus includes a first gas supply unit 70, a second gas supply unit 80, and a controller (control unit) 90, as shown in FIG. The first gas supply unit 70 supplies an inert gas, which is a first gas, to the pressurizing chamber 30 via the valves 71 and 72 and the gas supply path 31. Further, the first gas supply unit 70 releases the pressurization chamber 30 to the atmosphere via the gas supply path 31 and the valve 73. The second gas supply unit 80 supplies the inert gas, which is the second gas measured by the meter 83, into the stalk 40 via the valves 81 and 82, the gas supply path 521, and the gas supply path 621C of the valve mechanism 60. Supply.

  The controller 90 controls the opening and closing of the valves 71 to 73 and the valves 81 and 82 in order to control the supply of these inert gases.

  Next, a casting method using the casting apparatus according to the first embodiment will be described with reference to FIGS. 5 to 11 are schematic views showing the operation of the casting apparatus according to the first embodiment. FIG. 12 is a diagram illustrating changes in the pressure A in the stalk 40, the level B of the molten metal 10 in the stalk 40, and the pressure C in the pressurizing chamber 30.

  First, as shown in FIG. 5, at time t1, the fixed mold 51 and the movable mold 52 are closed with the pressurizing chamber 30 opened to the atmosphere. Then, an inert gas is supplied to the pressurizing chamber 30 through the gas supply path 31. Then, the level of the molten metal 10 in the pressurizing chamber 30 is lowered by the pressure of the inert gas, and the level of the molten metal 10 in the stalk 40 is increased. Thereby, as shown in FIG. 6, at the time t <b> 2, the molten metal 10 is filled into the cavity 50 through the stalk 40. Next, the pressure in the pressurizing chamber 30 is kept constant from time t2 to time t3.

  Subsequently, as shown in FIG. 7, the pressurizing chamber 30 is opened to the atmosphere at time t3. At this time, since the cavity 50 and the stalk 40 are in a vacuum state, the molten metal 10 in the stalk 40 does not fall. By releasing the pressurization chamber 30 to the atmosphere, energy required for pressurization of the pressurization chamber 30 can be reduced, and damage to the pressurization chamber 30 due to pressurization can be suppressed.

  When the pressure in the pressurizing chamber 30 decreases to the atmosphere, cooling of the fixed mold 51 and the movable mold 52 is started. As shown in FIG. 8, at time t <b> 4, the inert gas is introduced into the pressurizing chamber 30, and at the same time, the movable pin 62 of the valve mechanism 60 protrudes downward to introduce the inert gas into the stalk 40. By introducing the inert gas in the stalk 40, the molten metal 10 at the tip of the valve mechanism 60 moves downward, and a gas reservoir is formed at the upper end of the stalk 40 in the vicinity of the gate. At this time, the inert gas introduced into the stalk 40 is introduced in an amount measured by the meter 83. As shown in FIG. 12, the gas pressure in the pressurizing chamber 30 at this time is a pressure larger than the gas pressure in the stalk 40. Then, the gas pressure in the pressurizing chamber 30 and the gas pressure in the stalk 40 are controlled so as to gradually decrease toward the atmosphere release while maintaining a balance. As a result, the surface level of the molten metal 10 in the stalk 40 gradually decreases, and as shown in FIG. 9, both the pressurizing chamber 30 and the stalk 40 are reduced to atmospheric pressure at time t5.

  Subsequently, as shown in FIG. 10, the mold is opened at time t6, and as shown in FIG. 11, the product 10A is taken out by an unillustrated push pin at time t7.

  Here, unlike the present embodiment, a comparative example in which gas is not supplied into the pressurizing chamber 30 and the stalk 40 at times t4 to t5 will be considered. In this comparative example, when the mold chamber is opened after the pressurizing chamber 30 is released to the atmosphere, the molten metal surface of the molten metal 10 in the stalk 40 is rapidly lowered. Therefore, in the comparative example, air is easily mixed into the molten metal 10 in the stalk 40 or oxide is easily generated by entraining air in the stalk 40. Such air mixing and oxide generation deteriorate the quality of the product 10A.

  Therefore, in the present embodiment, in the control at the times t4 to t5 shown in FIGS. 8 and 9, the pressure in the stalk 40 and the pressurizing chamber 30 are reduced when the level of the molten metal in the stalk 40 is lowered. The pressure difference is gradually reduced while the pressure is balanced and both pressures are balanced. For this reason, in the present embodiment, when the pressurizing chamber 30 is released to the atmosphere, the molten metal surface of the molten metal 10 in the stalk 40 is gradually lowered as compared with the comparative example. Therefore, in the present embodiment, it is possible to suppress the entrainment of air into the stalk 40 as compared with the comparative example, and to suppress the air from being mixed into the molten metal 10 in the stalk 40 and the generation of oxides. Thereby, this Embodiment can suppress the fall of the quality of product 10A.

[Second Embodiment]
FIG. 13 is a diagram illustrating a casting method according to the second embodiment in which the pressure application pattern of the first embodiment is changed. In this embodiment, the inert gas is simultaneously introduced into the pressurizing chamber 30 and the stalk 40 without opening the pressurizing chamber 30 to the atmosphere at time t3. This second embodiment is applied when the cooling time of the molten metal 10 in the cavity 50 is sufficiently short.

  According to this embodiment, the time from the release of the atmosphere at time t3 to the pressurization in the pressurizing chamber 30 and stone 40 at time t4 in the previous embodiment can be shortened, and the time of one cycle can be shortened. Therefore, productivity can be improved.

[Third Embodiment]
FIG. 14 is a schematic view showing a casting apparatus according to the third embodiment. The present embodiment shows an example in which the present invention is applied to a low and medium pressure casting method. The casting apparatus is basically the same as that in FIG. 1, and the description of the parts overlapping with those in FIG. 1 is omitted.

  This casting apparatus includes a gate seal / pressurizing pin 100 that also serves as a valve mechanism instead of the valve mechanism 60 of FIG. The gate seal / pressure pin 100 is attached to the movable mold 52 so as to be movable forward and backward. The gate seal / pressure pin 100 has a double structure including an outer cylinder 101 and a movable pin 102 that is movably accommodated in the outer cylinder 101 and that protrudes forward and backward from the lower end of the outer cylinder 101. ing. The configuration of the gas supply path between the outer cylinder 101 and the movable pin 102 is the same as the structure of the movable pin 62 and the outer cylinder 61 in the previous embodiment.

  In this embodiment, when the molten metal 10 is filled into the cavity 50, the gate seal / pressure pin 100 itself protrudes from the movable mold 52 and pressurizes the molten metal 10. For this reason, the piston mechanism 103 as the driving means has a portion for driving the movable pin 102 and a portion for driving the entire gate seal / pressure pin 100 including the outer cylinder 101.

  Next, a casting method using the casting apparatus according to the third embodiment will be described with reference to FIGS. 15 to 24 are schematic views showing the operation of the casting apparatus according to the third embodiment. FIG. 25 is a diagram illustrating changes in the pressure A in the stalk 40, the level B of the molten metal 10 in the stalk 40, and the pressure C in the pressurizing chamber 30.

  First, as shown in FIG. 15, at time t1, the fixed mold 51 and the movable mold 52 are closed while the pressurizing chamber 30 is opened to the atmosphere. Then, an inert gas is supplied to the pressurizing chamber 30 through the gas supply path 31. Then, the level of the molten metal 10 in the pressurizing chamber 30 is lowered by the pressure of the inert gas, and the level of the molten metal 10 in the stalk 40 is increased. Thereby, as shown in FIG. 16, at time t <b> 2, the molten metal 10 is filled into the cavity 50 through the stalk 40. Next, as shown in FIG. 17, the gate seal / pressure pin 100 is pushed into the cavity 50 at time t <b> 3 to pressurize the cavity 50. At this time, the gate opening 511 is closed by the tip of the gate seal / pressure pin 100. The pressure in the cavity 50 is kept constant from time t3 to time t4.

  Subsequently, as shown in FIG. 18, the pressurizing chamber 30 is opened to the atmosphere at time t4. At this time, since the cavity 50 and the stalk 40 are in a vacuum state, the molten metal 10 in the stalk 40 does not fall. When the pressure in the pressurizing chamber 30 decreases to the atmosphere, cooling of the fixed mold 51 and the movable mold 52 is started. As shown in FIG. 19, at the time t5, the inert gas is introduced into the pressurizing chamber 30, and at the same time, the movable pin 102 of the gate seal / pressurizing pin 100 is protruded downward to bring the inert gas into the stalk 40. To introduce. With the introduction of the inert gas in the stalk 40, the molten metal 10 at the tip of the gate seal / pressure pin 100 moves downward to form a gas reservoir at the upper end of the stalk 40 in the vicinity of the gate. At this time, the inert gas introduced into the stalk 40 is introduced in an amount measured by the meter 83. As shown in FIG. 25, the gas pressure in the pressurizing chamber 30 at this time is a pressure larger than the gas pressure in the stalk 40. Then, the gas pressure in the pressurizing chamber 30 and the gas pressure in the stalk 40 are controlled so as to gradually decrease toward the atmosphere release while maintaining a balance. As a result, the surface level of the molten metal 10 in the stalk 40 gradually decreases, and as shown in FIG. 20, both the pressurizing chamber 30 and the stalk 40 are reduced to atmospheric pressure at time t6.

  Next, as shown in FIG. 21, the mold is opened at time t7, as shown in FIG. 22, the pressing pin 100 is retracted at time t8, and as shown in FIG. As shown in FIG. 24, the fixed mold 51 and the movable mold 52 are cleaned at time t10.

  According to this embodiment, the effects described in the first embodiment can be achieved even in low and medium pressure casting using the gate seal / pressure pin 100.

[Fourth Embodiment]
FIG. 26 is a diagram showing a casting method according to the fourth embodiment in which the pressure application pattern of the third embodiment is changed. In this embodiment, the inert gas is simultaneously introduced into the pressurizing chamber 30 and the stalk 40 without opening the pressurizing chamber 30 to the atmosphere at time t4.

  According to this embodiment, the time from the release of the atmosphere at time t4 to the pressurization in the pressurizing chamber 30 and stone 40 at time t5 in the previous embodiment can be shortened, and the time of one cycle can be shortened. Therefore, productivity can be improved.

  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.

  DESCRIPTION OF SYMBOLS 10 ... Molten metal, 10A ... Product, 20 ... Holding chamber, 21 ... Communication path, 22 ... Stopper, 30 ... Pressurizing chamber, 31 ... Gas supply path, 32 ... Hot water level detection rod, 40 ... Stoke, 50 ... Cavity, 51 ... fixed mold, 52 ... movable mold, 521 ... gas supply path, 60 ... valve mechanism, 61, 101 ... outer cylinder, 62, 102 ... movable pin, 70 ... first gas supply unit, 80 ... second gas supply , 90 ... Controller, 100 ... Gate seal / Pressure pin.

Claims (6)

A mold for forming a cavity having an opening below;
A pressurizing chamber that is disposed below the mold and accommodates the molten metal and forms a sealed space above the molten metal;
A cylindrical stalk in which an upper end opening communicates with the opening of the cavity and a lower end opening is immersed in the molten metal in the pressurized chamber;
A valve mechanism in which a distal end opening / closing part for opening and closing the gas passage faces the vicinity of the stalk upper part of the cavity;
First gas supply means for supplying a first gas to the sealed space of the pressurizing chamber;
Second gas supply means for supplying a second gas to the vicinity of the upper portion of the stalk of the cavity via the valve mechanism;
The first gas is introduced into the pressurizing chamber prior to the mold opening operation of the mold by controlling the first and second gas supply means, and the second gas is supplied to the vicinity of the stalk upper portion of the cavity. And a controller for lowering the molten metal level in the stalk to a level of the molten metal level in the pressurizing chamber while gradually decreasing the gas pressure of the first gas and the second gas. A casting apparatus characterized by that. The said control apparatus controls the said 1st and 2nd gas supply means so that the gas pressure of the said 1st gas may become larger than the gas pressure of the said 2nd gas. Casting equipment. The valve mechanism is
An outer cylinder penetrating the mold,
A movable pin that is movably accommodated in the outer cylinder, and whose tip advances and retreats from the lower end of the outer cylinder;
Driving means for driving the movable pin;
The casting apparatus according to claim 1, wherein the gas passage is formed between the outer cylinder and the movable pin, and the gas passage is opened and closed by advancing and retracting the movable pin. The valve mechanism is
A gate seal pin that movably penetrates the mold and closes the opening of the cavity, and an outer cylinder that also serves as a pressure pin that pressurizes the cavity;
A movable pin that is movably accommodated in the outer cylinder, and whose tip advances and retreats from the lower end of the outer cylinder;
Driving means for driving the outer cylinder and the movable pin;
The casting apparatus according to claim 1, wherein the gas passage is formed between the outer cylinder and the movable pin, and the gas passage is opened and closed by advancing and retracting the movable pin. A first step of filling the molten metal into the mold cavity through stalk having a lower end immersed in the molten metal by introducing a first gas into the pressurized chamber containing the molten metal and pressurizing the pressurized chamber; ,
The first gas is introduced into the pressurizing chamber and the second gas is introduced in the vicinity of the upper portion of the stalk of the cavity, and the molten metal in the stalk is gradually reduced while reducing the gas pressure of the first gas and the second gas. A second step of lowering the molten metal level to the level of the molten metal in the pressurized chamber;
A third step of opening the mold and taking out a cast product in the cavity. The casting method according to claim 5, wherein after the first step is completed, the first gas in the pressurizing chamber is released to the atmosphere prior to the second step.

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