JP2006346719A - Casting device, and casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for performing various and advanced casting. <P>SOLUTION: A die 20 forms a wheel forming space for a vehicle in a die clamped state. A first molten metal holding furnace 50 is arranged at the lower part of the die 20, and a plurality of second molten metal holding furnaces 60 are arranged at positions far from the lower part of the die 20. Molten metal in the first molten metal holding furnace 50 is fed to a center gate 25 in the die 20 via a tapping tube 35. A sealed pot 65 is stored in each second molten metal holding furnace 60, and the vicinity of the bottom part of the sealed pot 65 is provided with a tapping port and a molten metal feeding port capable of opening and closing. By a pressurizing operation at the sealed pot 65, the molten metal in the sealed pot 65 is fed to a side gate 26 of the die 20 via the tapping tube 36. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for casting a casting such as a vehicle wheel.

  Patent Document 1 discloses a low pressure casting apparatus that casts a vehicle wheel made of aluminum alloy (made of light alloy). In this apparatus, the molding space of the mold has a disk portion molding space and a rim portion molding space, a center gate is connected to the center of the disk portion molding space, and a plurality of rim portion molding spaces are separated in the circumferential direction. The side gates are connected.

A hot water discharge pipe (stalk) is connected to each of the center gate and the plurality of side gates, and a lower end portion of the hot water discharge pipe is immersed in the molten metal in one molten metal holding furnace. During casting, a pressurized gas is introduced into the molten metal holding furnace to pressurize the molten metal surface at a predetermined pressure so that the molten metal in the molten metal holding furnace is molded through a plurality of outlet pipes, center gates, and side gates. The molding space is filled.
JP 2001-287015 A

  In the low pressure casting apparatus of Patent Document 1, a molten metal having a predetermined composition held in a molten metal holding furnace is held at a predetermined temperature, and all the gates are collectively subjected to the same conditions, that is, the position of the molten metal surface in the stalk and the rise. The start time and the ascending speed are the same and are supplied to the mold. Therefore, advanced casting could not be performed. A description will be given of casting of a vehicle wheel as an example. The required casting characteristics and mechanical characteristics are different between the disk portion and the rim portion of the vehicle wheel. In the disk part, since the shape is complicated, high fluidity of the molten metal is required, but the toughness may be lower than that of the rim part. On the other hand, in the rim portion, the fluidity of the molten metal may be lower than that of the disk portion because the shape is simple, but high toughness is required because it receives a vibration load from the road surface.

However, since the vehicle wheel cast by the casting apparatus of Patent Document 1 has the same composition over the entire region, the molten metal composition satisfies both the high casting characteristics required for the disk portion and the high mechanical characteristics required for the rim portion. It was difficult to select and it was difficult to obtain the maximum characteristics required in each part.
In addition, for example, when casting a vehicle wheel, the molten metal is poured from the side gate before the molten metal is filled in the disk portion forming space, and a phenomenon that the molten metal falls on the molten metal in the disk portion forming space is caused. As a result, air bubbles remain in the metal, the oxide film on the surface of the molten metal breaks into the molten metal, and a new oxide film is formed.
Further, in the low-pressure casting apparatus, the height of the molten metal surface in the molten metal holding furnace is sequentially decreased every time one casting is completed, but the casting cycle needs to be constant. Therefore, control is performed to sequentially increase the applied pressure applied to the surface of the molten metal in the molten metal holding furnace, and not only the pressure control system becomes complicated, but also the pressure control device becomes expensive.
Furthermore, it is important to keep the amount of molten metal supplied to the molding space of the mold constant in order to obtain a cast product having stable quality, but the pressurized area by the pressurized gas is the molten metal in the molten metal holding furnace. Since the entire surface is formed, it is difficult to stably supply a constant amount of molten metal to the molding space of the mold.

The present invention has been made to solve the above problems, and in a casting apparatus, (a) a molding space, a mold having a first gate and a second gate connected to the molding space, and (a) the metal mold. A first molten metal holding furnace disposed below the mold; (c) a second molten metal holding furnace disposed at a position away from the lower side of the mold; and (d) one end communicating with the first gate. A first tapping pipe whose other end is immersed in the molten metal in the first molten metal holding furnace, and (e) supplying pressurized gas into the first molten metal holding furnace, A pressurized gas supply means for sending to the first gate; and (f) a sealed pot provided with a hot water inlet and a hot water outlet which are housed in the second molten metal holding furnace and can be opened and closed at a portion immersed in the molten metal; G) a second tapping pipe having one end connected to the second gate and the other end connected to the tapping outlet; A suction means for bringing the molten pot in the second molten metal holding furnace into the sealed pot with a negative pressure in the sealed pot with the hot water outlet closed and the hot water supply opening opened; And a pressurized gas supply means for supplying pressurized gas into the sealed pot and sending the molten metal in the sealed pot to the second gate through the second hot water discharge pipe with the hot water supply opening closed. It is characterized by that.
In another aspect of the casting apparatus, (a) a molding space, a mold having a first gate and a second gate communicating with the molding space, and (a) a molten metal supplied to the first gate are stored. A first molten metal holding furnace; (c) a second molten metal holding furnace for storing the molten metal supplied to the second gate; and (d) a first molten metal holding furnace and a second molten metal holding furnace, respectively. A sealed pot having a hot water outlet and a hot water outlet that can be opened and closed at a portion immersed in the water; and (e) a first hot water source having one end communicating with the first gate and the other end connected to the corresponding hot water outlet. A pipe, (f) a second hot-water pipe having one end connected to the second gate, and the other end connected to the corresponding hot-water outlet; Then, make the inside of the sealed pot negative pressure, and let the molten metal in the molten metal holding furnace flow into the sealed pot. With suction means and (g) with the hot water outlet opened and the hot water supply port closed, the pressurized gas is supplied to the sealed pot and the molten metal in the sealed pot is sent to the corresponding gate through the corresponding hot water pipe. And a pressurized gas supply means.

  According to the above configuration, since the first molten metal holding furnace and the second molten metal holding furnace are provided and the molten metal is supplied from the plurality of holding furnaces to the first and second gates, various and sophisticated castings can be performed. For example, the composition, temperature, supply pressure, melt supply timing, etc. of the melt can be selected for each melt holding furnace.

Preferably, the mold includes a fixed lower mold, an upper mold capable of moving up and down, and a plurality of horizontal molds disposed between the lower mold and the upper mold, and a first gate at the center of the lower mold. A center gate is formed, a plurality of side gates are formed as second gates between the horizontal molds, and a plurality of runners respectively connected to the side gates are formed in the lower mold. The second molten metal holding furnace is A plurality of them are arranged, and the sealed pots in the second molten metal holding furnace and the runners are connected to each other through the second hot water discharge pipe.
In this configuration, casting can be performed efficiently by using a plurality of second molten metal holding furnaces.

The present invention also provides a casting method using the above casting apparatus. In this casting method, the first molten metal holding furnace and the second molten metal holding furnace hold molten metals having different compositions, and the molten metal of these molten metal holding furnaces is supplied to the mold through the first and second hot water discharge pipes. , To obtain a cast product having a different composition depending on the part
According to this method, the molten metal components can be selected according to the casting characteristics and mechanical characteristics required for each part of the cast product, and these requirements can be answered at a high level.

  Preferably, in the first molten metal holding furnace and the second molten metal holding furnace, the molten metal temperature is controlled in accordance with the composition of the molten metal. Thereby, smooth casting can be performed corresponding to the molten metal from which a composition differs.

  As described above, according to the present invention, various and sophisticated castings can be realized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The illustrated apparatus is an apparatus for low-pressure casting a vehicle wheel (cast product) made of aluminum alloy (light alloy). As is well known, the vehicle wheel has a disc portion and a rim portion formed integrally with the periphery of the disc portion.

  As shown in FIG. 1, the low-pressure casting apparatus includes a support frame 10, a mold 20, a first molten metal holding furnace 50, and a plurality (four in the present embodiment) of second molten metal holding furnaces 60 as a basic configuration. As an element.

  The support frame 10 has a fixed base 11 at an intermediate height, and a lifting base 12 above the fixed base 11.

  The mold 20 includes a lower mold 21 fixed to the fixed base 11, an upper mold 22 fixed to the lifting base 12, and a horizontal mold 23 divided into a plurality (four in this embodiment) in the circumferential direction. And has.

  As shown in FIG. 2, in the mold clamping state of the mold 20, the side surfaces of the horizontal mold 23 are in contact with each other, the lower surface of the horizontal mold 23 is in contact with the lower mold 21, and the upper surface of the horizontal mold 23 is in contact with the upper mold 22. A wheel forming space 40 for casting the wheel is formed. The wheel forming space 40 has a disk portion forming space 40a and a rim portion forming space 40b connected to the periphery thereof.

  A center gate 25 (first gate) is formed at the center of the lower mold 21 and continues to the center of the disk portion forming space 40a. Further, a side gate 26 (second gate) connected to the rim portion forming space 40b is formed between the side surfaces of the adjacent horizontal molds 23. In the present embodiment, the horizontal mold 23 is divided into four, and four side gates 26 are formed. When the horizontal mold 23 is divided into two, two side gates 26 are formed. These side gates 26 are connected to a runner 27 formed in the lower mold 21.

  As shown in FIG. 1, an upper end portion (downstream end portion) of a tapping pipe 35 (first tapping pipe) connected to the center gate 25 is fixed to the fixing base 11, and the four runners 27 are connected to the fixing stand 11. The downstream ends of the hot water pipes 36 (second hot water pipes) to be connected to each other are fixed.

  The first molten metal holding furnace 50 is disposed below the mold 20, and includes a heat insulating container 51, a crucible 52 accommodated in the heat insulating container 51, and a heater 53 disposed on the inner periphery of the heat insulating container 51. have. The hot water pipe 35 connected to the center gate 25 extends vertically downward and penetrates the lid 51a of the heat insulating container 51, and the lower end thereof is immersed in the molten metal in the crucible 52.

  An air supply / exhaust pipe 57 also penetrates the lid 51a of the heat insulating container 51, and a pressurized gas supply means 59 is connected to the air supply / exhaust pipe 57 via an electromagnetic three-way valve 58 (valve means). . The pressurized gas supply means 59 includes a pressurized gas source and a pressure control means (both not shown).

  The four second molten metal holding furnaces 60 are arranged away from the lower side of the mold 20 and in the vicinity of the first molten metal holding furnace 50. Similar to the first molten metal holding furnace 50, these second molten metal holding furnaces 60 include a heat insulating container 61, a crucible 62 housed in the heat insulating container 61, and a heater 63 disposed on the inner periphery of the heat insulating container 61. is doing.

  In the second molten metal holding furnace 60, the upper end portion of the sealed pot 65 is fixed to the lid portion 61 a of the heat insulating container 61. The hermetic pot 65 hangs vertically and is immersed in the molten metal in the crucible 62. The upper end opening of the sealing pot 65 is sealed with a sealing member 65a.

  As shown in FIG. 3, a hot water supply port 65 x is formed at the bottom of each sealed pot 65. The hot water supply port 65x is opened and closed by raising and lowering a rod-shaped shut-off valve 71 (opening / closing means) connected to the cylinder 72.

  As shown in FIG. 1, the downstream end of each tapping pipe 36 is fixed to the fixing base 11 so as to be connected to the runner 27, and extends radially from here to the corresponding second molten metal holding furnace 60, The lid 61 a of the heat insulating container 61 is vertically penetrated, extends downward, and is immersed in the molten metal in the crucible 62. Further, the upstream end portion 36 a of the tap water pipe 36 extends horizontally and penetrates the peripheral wall in the vicinity of the bottom of the sealed pot 65 and enters the sealed pot 65, thereby constituting a part of the sealed pot 65.

  As shown in FIG. 3, a hot water outlet 36 x is formed at the upstream end 36 a of the hot water pipe 36. The hot water outlet 36x is opened and closed by raising and lowering a rod-shaped shut-off valve 73 (other opening / closing means) connected to the cylinder 74.

  As shown in FIG. 3, a supply / exhaust pipe 80 (communication path) passes through a sealing member 65 a that seals the upper end opening of the sealing pot 65, and an electromagnetic valve 81 (valve) is provided in the supply / exhaust pipe 80. The suction pump 82 (suction means) is connected via the means), and the pressurized gas supply means 84 is connected via the electromagnetic valve 83 (valve means). The pressurized gas supply means 84 includes a pressurized gas source and a pressure control means (both not shown).

  In addition, a heater (not shown) is wound around the outlet pipes 35 and 36 exposed to the outside.

A vehicle wheel low pressure casting method using the apparatus having the above configuration will be described in detail. In the crucible 52 of the first molten metal holding furnace 50, a molten aluminum alloy of JIS standard AC4CH used for casting of a normal vehicle wheel is held at about 700 ° C., and in the crucible 62 of the second molten metal holding furnace 60. Holds a molten aluminum alloy of JIS standard 6000 series such as 6061 at about 720 ° C.
In the second molten metal holding furnace 60, prior to the start of the casting operation, the hot water outlet 36x and the hot water inlet 65x are opened / closed, and the pressure in the sealed pot 65 is increased / decreased. Held in C.

  To supply the molten metal from the first molten metal holding furnace 50 to the mold 20, the three-way valve 58 is operated so that the air supply / exhaust pipe 57 and the pressurized gas supply means 59 communicate with each other. This is performed by supplying gas to the crucible 52. The molten metal in the crucible 52 is pushed by this pressurized gas and supplied to the disk part forming space 40a through the hot water discharge pipe 35 and the center gate 25, and the filling is completed. Then, when a predetermined time elapses with the molten metal filled, the supply of the pressurized gas is stopped and the three-way valve 58 is operated to open the crucible 52 to the atmosphere. Thereby, the hot water runs out in the center gate 25.

  On the other hand, in the second molten metal holding furnace 60, the molten metal in the crucible 62 is not supplied directly to the mold 20 but is supplied through the sealed pot 65. At the start of the casting operation, as described above, the hot water outlet 36x and the hot water inlet 65x are closed, and the molten metal in the hot water pipe 36 is maintained at the constant hot water surface level C. In this state, the hot water supply port 65x is opened, the open / close valve 83 is closed, the open / close valve 81 is opened, and the suction pump 82 is operated to make the inside of the sealed pot 65 have a negative pressure, and the molten metal in the crucible 62 is discharged. To flow into. When the level of the molten metal in the sealed pot 65 reaches a predetermined level H, this is detected by level detecting means such as a flow switch, the shutoff valve 71 is lowered to close the hot water supply port 65x, and the suction pump 82 is stopped. The on-off valve 81 is closed.

  Next, with the hot water supply port 65x closed, the hot water supply port 36x is opened and the on-off valve 83 is opened to supply pressurized gas to the sealed pot 65. As a result, the molten metal in the sealed pot 65 passes through the tap pipe 36 and is supplied to the rim portion forming space 40 b through the runner 27 and the side gate 26. When the level of the molten metal in the sealed pot 65 falls to the predetermined level L, this is detected by the level detecting means to stop the supply of the pressurized gas, and the pressure in the sealed pot 65 at this time is maintained. After a lapse of time, the pressure in the sealed pot 65 is lowered, a little molten metal in the hot water discharge pipe 36 is returned into the sealed pot 65 and drained, and then the shutoff valve 71 is lowered to close the hot water outlet 36x.

  The hot water may be cut by supplying an inert gas into the hot water outlet pipe 36.

  After closing the hot water outlet 36x, the hot water inlet 65x is opened again, and the above suction operation is performed at a predetermined timing to prepare for the next casting.

  Since the hot water outlet 36x is closed after the end of the hot water cutting, the molten metal does not return to the sealed pot 65 but remains in the hot water discharge pipe 36 and is maintained as the molten metal by heating the heater. Therefore, at the time of the next casting, the molten metal can be supplied to the side gate 26 immediately from the tapping pipe 36.

  During casting, the molten metal is supplied from the molten metal holding furnaces 50 and 60 to the mold 20 at substantially the same time, and is almost finished at the same time. The supply pressure and supply timing of these melts can be adjusted individually as appropriate. For the second molten metal holding furnace 60, common on-off valves 81 and 83, a suction pump 82, and a pressurized gas supply means 84 may be used.

  The molten aluminum alloy that fills the disk portion forming space 40a from the center gate 25 is AC4CH and contains a large amount of silicon. Therefore, even if the molten metal has high fluidity and the disk portion forming space 40a is complicated, the molten metal can be filled quickly and smoothly. In addition, since it contains a large amount of silicon, the shrinkage rate during solidification is small, and dimensional shrinkage can be minimized in the formation of a thick disk portion.

  The molten aluminum alloy filled from the side gate 26 into the rim part forming space 40b is 6000 series, and has less silicon than AC4CH filled into the disk part forming space 40a. Therefore, the molded rim portion can have high toughness. Although this molten metal has a lower fluidity than AC4CH, the rim portion molding space 40b has a relatively simple shape, and therefore does not hinder filling. In addition, this molten metal has a higher shrinkage rate than AC4CH, but since the rim portion molding space 40b is thin, the shrinkage of the size is small and does not cause a problem.

FIG. 4 shows a casting apparatus according to the second embodiment, and the same reference numerals are given to the components corresponding to the first embodiment, and detailed description thereof is omitted.
In this casting apparatus, a closed pot 65 is disposed in the first molten metal holding furnace 50 in the same manner as the second molten metal holding furnace 60. Then, the molten metal is supplied to the disk portion forming space 40a through the outlet pipe 35 and the center gate 25 in the same manner as the second molten metal holding furnace.

  The present invention is not limited to the above embodiment, and various forms can be adopted. For example, in the above embodiment, the molten metal held in the plurality of second molten metal holding furnaces 60 has the same composition, but the molten metal composition may be different for each second molten metal holding furnace 60. Moreover, the molten metal components of the first molten metal holding furnace and the second molten metal holding furnace may be the same, and the molten metal temperature control, the molten metal supply pressure, and the molten metal supply disclosure time may be different.

  When the molten metal composition to the plurality of side gates 26 is the same, a common second molten metal holding furnace 60 may be used. That is, the plurality of hot water discharge pipes 36 connected to the plurality of side gates 26 are connected to the plurality of sealed pots 65 in the common second molten metal holding furnace 60.

  The rim molding part of the mold may mold a rim part much thicker than the rim part of the final product. In this case, the final rim shape or a shape close to it is obtained by spinning the rim portion after casting.

The present invention can be applied to casting of a cast product that requires different characteristics for each part in addition to the vehicle wheel.
In the said embodiment, although the molten metal holding furnace was comprised with the crucible type | mold holding furnace, you may comprise with a bath type holding furnace as shown in FIG. Reference numeral 53A denotes a horizontal immersion heater.
Moreover, in the said embodiment, although the upstream end part 36a of the tap pipe 36 was located in the sealing pot 65, and the cutoff valves 71 and 73 were arrange | positioned in the sealing pot 65, as shown in FIG. 73 may be arranged outside the sealed pot 65.

It is a longitudinal cross-sectional view of the low-pressure casting apparatus of the vehicle wheel concerning 1st Embodiment of this invention. It is an expanded sectional view which shows the principal part of the metal mold | die of the apparatus in a clamping state. It is a principal part expanded sectional view of the 2nd molten metal holding furnace of the apparatus. It is a principal part longitudinal cross-sectional view of the low pressure casting apparatus which makes 2nd Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the low pressure casting apparatus which makes 3rd Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the low pressure casting apparatus which makes 4th Embodiment of this invention.

Explanation of symbols

20 Mold 25 Center gate (first gate)
26 Side gate (second gate)
35 First hot water pipe 36 Second hot water pipe 36x Hot water outlet 40 Vehicle wheel forming space 40a Disk part forming space 40b Rim part forming space 50 First molten metal holding furnace 60 Second molten metal holding furnace 65 Sealed pot 65x Hot water supply holes 71, 73 Shut-off valve (open / close means)
82 Suction pump (suction means)
84 Pressurized gas supply means

Claims (5)

(A) a molding space, and a mold having a first gate and a second gate connected to the molding space;
(A) a first molten metal holding furnace disposed below the mold;
(C) a second molten metal holding furnace disposed at a position away from the lower side of the mold;
(D) a first tapping pipe having one end communicating with the first gate and the other end immersed in the molten metal in the first molten metal holding furnace;
(E) pressurized gas supply means for supplying pressurized gas into the first molten metal holding furnace and sending the molten metal in the first molten metal furnace to the first gate;
(F) a sealed pot equipped with a hot water supply port and a hot water outlet that are housed in the second molten metal holding furnace and can be opened and closed at a portion immersed in the molten metal;
(G) a second tapping pipe having one end connected to the second gate and the other end connected to the tapping outlet;
(H) a suction means for making the inside of the sealed pot negative pressure and allowing the molten metal in the second molten metal holding furnace to flow into the sealed pot with the hot water outlet closed and the hot water supply port opened;
(K) Pressurized gas that supplies pressurized gas into the sealed pot and sends the molten metal in the sealed pot to the second gate through the second outlet pipe in a state where the hot water outlet is opened and the hot water supply port is closed. Supply means;
A casting apparatus comprising: (A) a molding space and a mold having a first gate and a second gate communicating with the molding space;
(A) a first molten metal holding furnace for storing the molten metal supplied to the first gate;
(C) a second molten metal holding furnace for storing the molten metal supplied to the second gate;
(D) a sealed pot equipped with a hot water supply port and a hot water outlet that are housed in the first molten metal holding furnace and the second molten metal holding furnace, respectively, and can be opened and closed at a portion immersed in the molten metal;
(E) a first tapping pipe having one end communicating with the first gate and the other end connected to the corresponding tapping outlet;
(F) a second tapping pipe having one end connected to the second gate and the other end connected to the corresponding tapping outlet;
(G) a suction means for making the inside of the sealed pot negative pressure and allowing the molten metal in the molten metal holding furnace to flow into the sealed pot with the hot water outlet closed and the hot water supply port opened;
(H) Supplying pressurized gas to the sealed pot with the hot water outlet opened and closing the hot water supply port, and sending the molten metal in the sealed pot to the corresponding gate via the corresponding hot water pipe Means,
A casting apparatus comprising: The mold includes a fixed lower mold, an upper mold capable of moving up and down, and a plurality of horizontal molds arranged between the lower mold and the upper mold, and a center gate as a first gate in the center of the lower mold A plurality of side gates are formed as second gates between the horizontal molds, and a plurality of runners are formed in the lower mold, respectively.
The said 2nd molten metal holding furnace is arrange | positioned in multiple numbers, The sealed pot in these 2nd molten metal holding furnaces, and the said runner are connected via the 2nd hot water discharge pipe, respectively. Casting equipment.   Using the casting apparatus according to claims 1 to 3, the first molten metal holding furnace and the second molten metal holding furnace hold molten metals having different compositions, and the molten metal of these molten metal holding furnaces is connected to the first and second outlet pipes. A casting method characterized in that a cast product having a different composition depending on a part is obtained by supplying it to a mold.   5. The casting method according to claim 4, wherein in the first molten metal holding furnace and the second molten metal holding furnace, the molten metal temperature is controlled in accordance with the composition of the molten metal.

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