JP2011147955A - Molten metal supply method in half-solidified metal casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molten metal supply method in half-solidified metal casting, by which excessive solidified metal does not stuck to a ladle, and continuous casting can be performed at stable cycle and product quality. <P>SOLUTION: The molten metal supply method in half-solidified metal casting supplies a molten metal 40 to an injection sleeve 30 via an implement 18 for cooling to thereby obtain a half-solidified metal slurry 74, then injection-molds the half-solidified metal slurry 74 into the cavity 28 of a die 12 to thereby mold a casting. In the method, the molten metal 40 in a molten metal holding furnace 50 is pumped out by the ladle 52, the molten metal 40 is cooled to a prescribed temperature range in the ladle 52, and the molten metal 40 with temperature reduced to the prescribed temperature range is supplied to the injection sleeve 30 via the implement 18 for cooling. The temperature of the molten metal 40 in the molten metal holding furnace 50 lies in the range of +30°C to +50°C relative to the liquidus temperature of the molten metal 40, and the prescribed temperature range lies in the range of +10°C to +20°C relative to the liquidus temperature of the molten metal 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a molten metal supply method in semi-solid metal casting in which after obtaining a semi-solid metal slurry from a molten metal, the semi-solid metal slurry is injected into a cavity of a mold.

  In general, in semi-solid metal casting, there is, for example, a method described in Patent Document 1 as a molten metal supply method for supplying a cooling jig to semi-solidify a molten metal.

  In the method described in Patent Document 1, the molten metal to which the micronizing agent is added is distributed from a high-temperature holding furnace that holds the liquidus temperature + 50 ° C. (650 ° C.) or higher, and the molten metal is held at the liquidus temperature + 50 ° C. or lower. Using a low temperature holding furnace, the hot water ladle is used to pour hot water from the low temperature holding furnace into a holding vessel which is a nucleation unit. When the pouring temperature at that time includes only Ti (titanium) as a refinement additive, the liquidus temperature is kept at + 30 ° C. or lower, and Sr (strontium) and Ca (calcium) combined additives or Ca In an Mg (magnesium) alloy added by itself, a semi-solid metal having a fine spherical primary crystal is obtained by maintaining the liquidus temperature at + 25 ° C. or lower.

Japanese Patent No. 3211754

  In the method of supplying a molten metal, there are generally at least four problems as described below.

[Issue 1: Space saving, energy saving, cost reduction]
Normally, when the molten metal is brought into contact with the cooling jig and semi-solidified and supplied to the semi-solid metal casting apparatus, the cooling jig is installed in a limited space around the pouring port of the semi-solid metal casting apparatus. From the viewpoint of the degree of freedom in layout, it is desirable that the cooling jig is small in size. Here, when the pouring temperature to the cooling jig is high, it is necessary to increase the size of the cooling jig in order to obtain a semi-solid metal having a desired solid phase ratio.

In Patent Document 1 described above, both a high-temperature holding furnace and a low-temperature holding furnace are provided. However, there is a problem that equipment space becomes large and versatility is poor. Also, by providing two holding furnaces, the amount of power used increases and the amount of CO ₂ emissions also increases. Furthermore, since the fine additive is supplied, there is a problem that the material cost of the product is increased.

[Problem 2: Amount of solidified metal piece (yield)]
For example, when the shape of the cooling jig is a plate shape, it is desirable that the size of the cooling jig is small in order to reduce the amount of solidified metal pieces generated on the cooling jig. The amount of the solidified metal piece is also desired to be reduced from the viewpoint of the material (semi-solidified metal slurry) and the product yield.

  However, when the pouring temperature to the cooling jig is high, it is necessary to increase the size of the cooling jig in order to obtain a semi-solid metal having a desired solid phase ratio. There is a problem that the yield of materials and products deteriorates.

[Problem 3: Low temperature of molten metal]
In order to solve the problems 1 and 2 described above, it is necessary to lower the pouring temperature. For this reason, when the temperature of the molten metal (holding temperature) in the molten metal holding furnace is lowered, the following problems occur. appear.

  When the molten metal is pumped by the hot water supply device, if the holding temperature of the molten metal holding furnace is lowered (liquidus temperature + 30 ° C. or lower), for example, when pumping by a ladle, the molten metal may solidify at the edge of the ladle. If the continuous operation is carried out as it is, there is a problem that the molten metal solidifies and deposits and the solidified metal grows with the solidified mass adhering to the edge of the ladle as the core. This solidified mass may cause damage to the ladle, interference with surrounding equipment, or the like. In addition, there is a problem that the quality of the product deteriorates when the solidified lump is mixed in the ladle when the molten metal is pumped or dropped into the pouring port when pouring into the cooling jig and mixed into the semi-solid metal slurry. is there.

[Problem 4: Grain coarsening]
In Patent Document 1, the pouring temperature to the nucleation part is set to the liquidus temperature + 25 ° C. or lower or 30 ° C. or lower, but the temperature of the molten metal becomes the liquidus temperature or lower in the ladle before pouring. Because the cooling rate of the molten metal is low, the frequency of crystal nucleation is reduced and the crystal is likely to be coarse. As a result, there is a problem that a coarse structure is mixed in the product and the strength required for the product cannot be obtained.

  The present invention has been made in consideration of such problems, and does not allow extra solidified metal to adhere to the ladle, and provides molten metal in semi-solid metal casting that enables continuous casting with stable cycle and product quality. It aims to provide a method.

[1] The method for supplying molten metal in semi-solid metal casting according to the present invention is to supply a molten metal to an injection sleeve via a cooling jig to obtain a semi-solid metal slurry, and then to add the semi-solid metal slurry to gold In a molten metal supply method in semi-solid metal casting in which a cast product is formed by injection molding into a mold cavity, a step of pumping out the molten metal in the molten metal holding furnace with a ladle, and the molten metal in the ladle at a specified temperature A step of cooling to a range, and a step of supplying the molten metal lowered to the specified temperature range in the ladle to the injection sleeve through the cooling jig, and setting a liquidus temperature of the molten metal. Ta (° C.), the temperature of the molten metal in the molten metal holding furnace is Tb (° C.), the specified temperature range is Tc (° C.), and the temperature of the molten metal discharged from the cooling jig is Td (° C. ), Tb> A c> Ta> Td, and, and satisfies the Tb ≧ (Ta + 30 ℃).

  As a result, the frequency of crystal nucleation in the semi-solidified metal can be improved without the need for refined additives, and a fine and spherical semi-solid metal can be obtained. Further, since only one molten metal holding furnace is required, space saving, energy saving, and low cost can be promoted. In addition, a desired semi-solid metal slurry can be stably obtained regardless of variation in holding temperature, and stable product quality can be obtained.

[2] In the present invention, the temperature of the molten metal in the molten metal holding furnace is in a range of + 30 ° C. to + 50 ° C. with respect to the liquidus temperature of the molten metal, and the specified temperature range is the temperature of the molten metal. It is characterized by being in the range of + 10 ° C. to + 20 ° C. with respect to the liquidus temperature. As a result, when the molten metal is pumped from the molten metal holding furnace using the ladle, the solidified metal does not adhere to the ladle.

[3] In the present invention, in the step of cooling the molten metal to a specified temperature range in the ladle, the molten metal is transferred by transferring the molten metal from the ladle that has pumped the molten metal from the molten metal holding furnace to another ladle. It is characterized by cooling. Thus, the cycle time can be shortened because the molten metal can be actively cooled without waiting for the molten metal temperature to naturally fall within the ladle.

  As described above, according to the molten metal supply method in semi-solid metal casting according to the present invention, excessive solid metal does not adhere to the ladle, and continuous casting can be performed with a stable cycle and product quality.

It is a block diagram which shows a 1st pressure casting apparatus. It is a perspective view which shows the jig | tool for cooling inclined and installed with respect to the perpendicular direction. It is a flowchart which shows a 1st molten metal supply method. It is a block diagram which shows a 2nd pressure casting apparatus. It is a flowchart which shows a 2nd molten metal supply method. It is a characteristic view which shows the change of the exit temperature of the cooling jig with respect to the pouring temperature (pouring hot water temperature) to the cooling jig. It is a characteristic view which shows the relationship between the solid-phase rate and temperature of the component lower limit of the molten metal used in the Example, and an upper limit of a component.

  Hereinafter, an embodiment of a molten metal supply method in semi-solid metal casting according to the present invention will be described with reference to FIGS. In the present specification, “˜” indicating a numerical range is used as a meaning including numerical values described before and after the numerical value as a lower limit value and an upper limit value.

  First, as shown in FIG. 1, a semi-solid metal casting apparatus (hereinafter referred to as a semi-solid metal casting apparatus 10A) according to the first embodiment includes a mold 12, a mold driving unit 14, and an injection mechanism. 16, a cooling jig 18, a molten metal supply mechanism 20, and a supply control unit 22 that controls the molten metal supply mechanism 20.

  The mold 12 includes a movable mold 24 and a fixed mold 26. The movable mold 24 is driven by the mold driving unit 14 and moves in the forward / backward direction with respect to the fixed mold 26. When the movable mold 24 is combined with the fixed mold 26 (mold closed state), the movable mold 24 is interposed between the fixed mold 26 and the movable mold 24. A cavity 28 is formed as a casting space.

  The injection mechanism 16 includes an injection sleeve 30, a plunger 32, and an injection drive unit 34. The injection sleeve 30 is formed in a cylindrical shape having a hollow portion, and the distal end portion thereof is inserted into the fixed mold 26 so that the hollow portion and the cavity 28 of the mold 12 are provided with a current divider 36 provided in the movable mold 24 and Communication is made through a runner 37 provided in the fixed mold 26. An opening is formed in the rear end portion of the injection sleeve 30, and the plunger 32 is inserted through this opening. A pouring port 38 is provided at an upper portion near the rear end of the injection sleeve 30.

  The plunger 32 is driven by the injection drive unit 34 and moves in the forward and backward direction with respect to the mold 12 in the hollow portion of the injection sleeve 30.

  The cooling jig 18 is configured as a long object, and is installed to be inclined at a predetermined angle with respect to the vertical direction so as to guide the molten metal 40 to the injection sleeve 30 at a predetermined flow rate. At this time, the lower end portion of the cooling jig 18 is installed so as to face the pouring port 38 of the injection sleeve 30.

  In this case, as shown in FIG. 2, the cooling jig 18 includes a bottom portion 42, and a first side portion 44 a and a second side portion 44 b that are bent and connected to each side end portion of the bottom portion 42. A space surrounded by the bottom portion 42, the first side portion 44a, and the second side portion 44b functions as the flow groove 46. Further, the presence of the first side portion 44a and the second side portion 44b prevents the molten metal 40 (or semi-solidified slurry) from overflowing and dropping from the side of the cooling jig 18.

  The molten metal supply mechanism 20 stores the molten metal 40, a molten metal holding furnace 50 that adjusts the components of the molten metal 40, and a ladle 52 that pumps the molten metal 40 in the molten metal holding furnace 50 by a predetermined amount and supplies the molten metal 40 to the cooling jig 18. A ladle driving unit 54 for driving the ladle 52 to pump out the molten metal 40 from the molten metal holding furnace 50 and supplying the molten metal 40 to the cooling jig 18; and the ladle 52 with the molten metal holding furnace 50 and the cooling jig. And a ladle conveying mechanism 56 that reciprocates between the two.

  The supply control unit 22 includes a molten metal pumping control unit 58, a transfer time setting unit 60, a ladle transfer control unit 62, a transfer time measuring unit 64, a molten metal temperature calculation unit 66, a determination unit 68, and a molten metal supply / discharge control. Part 70.

  The molten metal pumping control unit 58 controls the ladle driving unit 54 so that the molten metal 40 in the molten metal holding furnace 50 is pumped by the ladle 52.

  The conveyance time setting unit 60 sets the conveyance time of the ladle 52 based on the temperature data of the molten metal 40 in the molten metal holding furnace 50.

  The ladle transport control unit 62 transports the ladle 52 by controlling the ladle transport mechanism 56 based on the set transport time.

  The conveyance time measuring unit 64 measures the elapsed time from the conveyance start time of the ladle 52 to the conveyance end time. When the conveyance of the ladle 52 is completed, a detection signal from the position sensor 72 that detects the arrival of the ladle 52 at the upper end of the cooling jig 18, that is, the ladle 52 has reached the upper end of the cooling jig 18. The output time point of the detection signal from the position sensor 72 indicating can be used.

  The molten metal temperature calculation unit 66 calculates the temperature of the molten metal 40 in the ladle 52 when the ladle 52 reaches the upper end of the cooling jig 18.

  The discriminating unit 68 discriminates whether or not the temperature of the molten metal 40 obtained by the calculation satisfies a specified temperature range.

  The molten metal supply / discharge control unit 70 supplies the molten metal 40 in the ladle 52 to the cooling jig 18 when the temperature of the molten metal 40 calculated by the calculation satisfies a specified temperature range. Further, when the specified temperature range is not satisfied, the ladle driving unit 54 is controlled so as to discard the molten metal 40 in the ladle 52 without supplying it to the cooling jig 18 (steel hot water).

  Here, a molten metal supply method (hereinafter, referred to as a first molten metal supply method) by the first semi-solid metal casting apparatus 10A will be described with reference to the flowchart of FIG.

  First, in step S <b> 1 of FIG. 3, the molten metal pumping control unit 58 controls the ladle driving unit 54 to pump the molten metal 40 in the molten metal holding furnace 50 with the ladle 52.

  Thereafter, in step S <b> 2, the transfer time setting unit 60 determines the temperature data (melt furnace temperature data) of the molten metal 40 in the molten metal holding furnace 50, the temperature decrease rate data of the ladle 52, and the cooling jig 18 from the ladle 52. The specified temperature range data of the molten metal 40 immediately before being supplied to is acquired. The melt temperature data in the furnace includes data input by the user using the console, data from a thermometer installed in the melt holding furnace 50, and the like (data in the furnace) Melt temperature data). The temperature decrease rate of the ladle 52 indicates the degree of temperature decrease per unit time of the molten metal 40 put in the ladle 52, and is determined by the shape, volume, and material of the ladle 52. The temperature decrease rate is obtained in advance and stored as data (temperature decrease rate data) in the memory of the supply control unit 22. The specified temperature range of the molten metal 40 immediately before being supplied to the cooling jig 18 is such that the temperature when the molten metal 40 supplied by the ladle 52 comes out of the cooling jig 18 (the outlet temperature of the cooling jig 18). The temperature is set in advance so as to be lower than the liquidus temperature of the molten metal 40 and is stored as data (specified temperature range data) in the memory of the supply control unit 22. Therefore, the conveyance time setting unit 60 reads out the molten metal temperature data, the temperature decrease rate data, and the specified temperature range data from the memory in step S2.

  Thereafter, in step S3, the transfer time setting unit 60 sets the transfer time of the ladle 52 based on the acquired molten metal temperature data, temperature decrease rate data, and specified temperature range data.

In this first molten metal supply method, the liquidus temperature of the molten metal 40 is Ta (° C.), the molten metal temperature in the furnace is Tb (° C.), the specified temperature range is Tc (° C.), and the outlet temperature of the cooling jig 18 is set. When Td (° C.)
Tb>Tc>Ta> Td
And Tb ≧ (Ta + 30 ° C.)
Is set to satisfy.

  Specifically, the molten metal temperature in the furnace was set to the liquidus temperature of the molten metal 40 + 30 ° C. to + 50 ° C., and the specified temperature range was set to the liquidus temperature of the molten metal 40 + 10 ° C. to + 20 ° C. As the ladle 52, a ladle having a temperature decrease rate of 0.1 to 3.0 ° C./second was used. Usually, it is known that the temperature of the molten metal in the ladle 52 immediately after the molten metal 40 of the molten metal holding furnace 50 is pumped by the ladle 52 is lowered by about 10 ° C. from the holding temperature because the molten metal 40 is cooled in the pumping process. That is, the temperature of the molten metal in the ladle 52 immediately after pumping is the liquidus temperature of the molten metal 40 + 20 ° C. to + 40 ° C. Therefore, the above-described transport time is set, for example, within a range shown in Table 1 below. Thereby, the supply temperature (pouring temperature) to the cooling jig 18 can be set within the range of the liquidus temperature of the molten metal + 10 ° C. to 20 ° C. The example shown in Table 1 is merely a representative example.

  Thereafter, in step S4, the ladle transport control unit 62 controls the ladle transport mechanism 56 based on the set transport time to transport the ladle 52. In the transport of the ladle, the transport time counting unit 64 counts the time from the start of transport of the ladle 52 by the ladle transport mechanism 56 to the end of transport of the ladle 52.

  Thereafter, in step S5, the molten metal temperature calculation unit 66 is based on the information that the temperature of the molten metal 40 is lowered by about 10 ° C. from the holding temperature in the pumping process, the molten metal temperature data, the temperature decrease rate data, and the measured transfer time. Thus, the temperature of the molten metal 40 in the ladle 52 at the stage when the ladle 52 reaches the upper end of the cooling jig 18 (melt temperature in the ladle) is calculated.

  Thereafter, in step S6, the determination unit 68 determines whether or not the melt temperature in the ladle determined by the melt temperature calculation unit 66 is within a specified temperature range indicated by the temperature range data.

  If the melt temperature in the ladle is within the specified temperature range, the process proceeds to step S7, where the melt supply / discharge control unit 70 controls the ladle drive unit 54 to cool the melt 40 in the ladle 52. Supply (pour) from the upper end of the tool 18.

  On the other hand, when the melt temperature in the ladle is not within the specified temperature range, the process proceeds to step S8, and the melt supply / discharge control unit 70 controls the ladle drive unit 54 to cool the melt 40 in the ladle 52. Discard without supplying to the tool 18 (steel hot water).

  Thereafter, in step S9, it is determined whether or not there is an end request for the molten metal supply process, and if there is no end request, the process returns to the process after step S1 (continuous operation). In step S9, when there is an end request, the process using the first molten metal supply method ends.

  In step S7 described above, when the molten metal 40 in the ladle 52 is supplied from the upper end of the cooling jig 18, the supplied molten metal 40 follows the flow groove 46 (see FIG. 2) of the cooling jig 18. Then, it flows toward the lower end of the inclined cooling jig 18. In this process, heat is taken away by the cooling jig 18, and as a result, a part thereof becomes a solid phase. That is, the molten metal 40 is gradually transformed into a semi-solid metal slurry 74 in which a solid phase and a liquid phase coexist while being guided by the cooling jig 18.

  Most of the semi-solid metal slurry 74 is guided to the flow groove 46 and transferred from the pouring port 38 of the injection sleeve 30 to the inside of the injection sleeve 30.

  After a predetermined amount of semi-solid metal slurry 74 is introduced into the injection sleeve 30, the plunger 32 moves forward (moves toward the mold 12) by the injection drive unit 34. As a result, the semi-solid metal slurry 74 in the injection sleeve 30 is pressed and filled into the cavity 28 of the mold 12 through the diverter 36 and the runner 37.

  Thereafter, the semi-solid metal slurry 74 is cooled and solidified in the cavity 28, whereby a cast product is obtained. This cast product is taken out from the cavity 28 by so-called mold opening.

  As described above, in the first molten metal supply method, the temperature (holding temperature) of the molten metal 40 in the molten metal holding furnace 50 is lowered, and the supply temperature (pouring temperature) to the cooling jig 18 is changed to the liquid phase of the molten metal 40. Since the temperature is controlled at + 10 ° C. to 20 ° C., the frequency of crystal nucleation in the semi-solid metal can be improved without the need for refined additives, and the fine and spherical semi-solid structure. The metal can be obtained.

  Since only one molten metal holding furnace 50 is required, space saving, energy saving, and low cost can be promoted.

  Since the holding temperature of the molten metal holding furnace 50 is controlled at the liquidus temperature of the molten metal 40 + 30 ° C. to 50 ° C., when the molten metal 40 is pumped from the molten metal holding furnace 50 using the ladle 52, Solidified metal will not adhere. Further, a ladle having a temperature decrease rate of 0.1 to 3.0 ° C./second is used as the ladle 52, and the conveyance time of the ladle 52 is determined based on the degree of the temperature decrease of the molten metal 40 immediately after being pumped to the ladle 52 and the ladle used. Since the temperature is set in accordance with the temperature decrease rate of 52, the supply temperature (pouring temperature) to the cooling jig 18 can be set within the range of the liquidus temperature of the molten metal + 10 ° C. to 20 ° C. .

  Further, in the present embodiment, the conveyance time of the ladle 52 is set based on the holding temperature of the molten metal holding furnace 50 and the pouring temperature to the cooling jig 18 is controlled. Regardless of variations, the desired semi-solid metal slurry 74 can be stably obtained, and stable product quality can be obtained.

  By the way, there is a case where the ladle 52 temporarily stops (so-called chocolate stop: short time breakdown) due to a temporary trouble of the ladle driving unit 54 and the ladle transport mechanism 56. In such a case, the ladle 52 may reach the upper end of the cooling jig 18 exceeding the conveyance time set in step S3 of FIG. ) May be outside the specified temperature range, that is, outside the range of the liquidus temperature of the molten metal 40 + 10 ° C to 20 ° C. If molten metal 40 outside the specified temperature range is poured into the cooling jig 18, the product quality may be adversely affected.

  Therefore, in this embodiment, the ladle 52 is transported based on the set transport time. At this time, the actual transport time of the ladle 52 is measured, and the ladle 52 is cooled based on the measured actual transport time. The temperature of the molten metal 40 in the ladle 52 when it reaches the upper end of the jig 18 is calculated, and it is determined whether or not the temperature of the molten metal 40 obtained by the calculation satisfies a specified temperature range. When the temperature range is satisfied, the molten metal 40 in the ladle 52 is supplied to the cooling jig 18, and when the specified temperature range is not satisfied, the molten metal 40 in the ladle 52 is discarded (steel hot water). Therefore, it is possible to avoid an unexpected situation that the molten metal 40 outside the specified temperature range is poured into the cooling jig 18.

  When the transport time of the ladle 52 exceeds the upper limit of the transport time corresponding to the temperature decrease rate of the ladle 52 (for example, 200 seconds if the temperature decrease rate is 0.1 ° C./second), the molten metal 40 in the ladle 52 is used. Among these, since the part in contact with the wall surface of the ladle 52 and the part in contact with the air are preferentially cooled, there is a problem that a distribution (temperature distribution) having a difference in temperature is greatly generated.

  In addition, as a specified temperature range, when the liquidus temperature of the molten metal 40 is aimed at less than + 10 ° C., the metal component of the molten metal 40 varies due to reasons such as hot water distribution to the molten metal holding furnace 50 during continuous operation. If the liquidus temperature changes, there is a possibility that the pouring temperature to the cooling jig 18 is lower than the liquidus temperature. At that time, a coarse structure is generated in the ladle 52, which adversely affects the product quality. As a method for avoiding this, a method of measuring the metal component of the molten metal 40 in the molten metal holding furnace 50 in real time and capturing the change in the liquidus temperature during continuous operation is conceivable. It is difficult.

  On the other hand, when a temperature exceeding the liquidus temperature + 20 ° C. of the molten metal 40 is aimed as a specified temperature range, it is necessary to improve the cooling capacity (heat removal capacity) with the cooling jig accordingly. However, there is a problem that the size of the cooling jig must be increased, and there is a limit to space saving and yield improvement.

  Next, a semi-solid metal casting apparatus (hereinafter referred to as a second semi-solid metal casting apparatus 10B) according to a second embodiment will be described with reference to FIG.

  The second semi-solid metal casting apparatus 10B has substantially the same configuration as the above-described first semi-solid metal casting apparatus 10A, but as shown in FIG. 4, a plurality of ladles (for example, the first ladle 52a and the second ladle). 52b) is different.

  That is, the second semi-solid metal casting apparatus 10B drives the first ladle 52a to pump out the molten metal 40 from the molten metal holding furnace and supply (transfer) the molten metal 40 to the second ladle 52b. And a second ladle driving unit 54b that drives the second ladle 52b to receive the molten metal poured from the first ladle 52a and supply the molten metal 40 to the cooling jig 18. The ladle transport mechanism 56 transports the second ladle 52b back and forth between the initial position and the cooling jig 18.

  Here, a molten metal supply method (hereinafter referred to as a second molten metal supply method) by the second semi-solid metal casting apparatus 10B will be described with reference to the flowchart of FIG. In addition, since this 2nd molten metal supply method performs the process substantially the same as the 1st molten metal supply method shown in FIG. 3, the duplication description is abbreviate | omitted.

  First, in step S101 in FIG. 5, the molten metal pumping control unit 58 controls the first ladle driving unit 54a to pump the molten metal 40 in the molten metal holding furnace 50 with the first ladle 52a.

  Thereafter, in step S102, the molten metal supply / discharge control unit 70 controls the first ladle driving unit 54a to pour (transfer) the molten metal 40 in the first ladle 52a into the second ladle 52b. In this transfer, the pouring amount per unit time is set to 0.6 to 6.0 kg / second.

  After that, in step S103, the transfer time setting unit 60 performs cooling from the temperature data of the molten metal in the molten metal holding furnace 50 (in-furnace molten metal temperature data), the temperature decrease rate data of the second ladle 52b, and the second ladle 52b. The specified temperature range data of the molten metal immediately before being supplied to the jig 18 is acquired.

  Thereafter, in step S104, the transport time setting unit 60 sets the transport time of the second ladle 52b. As described above, the temperature of the molten metal is lowered by about 10 ° C. from the holding temperature in the pumping process in the first ladle 52a. In addition, when pouring the molten metal from the first ladle 52a to the second ladle 52b (transfer), the amount of pouring per unit time is set to 0.6 to 6.0 kg / sec. In the process of transferring the molten metal 40 to the two ladle 52b, the temperature of the molten metal 40 is reduced by about 10 ° C. from the temperature in the first ladle 52a. That is, at the stage where the molten metal is poured into the second ladle 52b, the temperature of the molten metal 40 is lowered by about 20 ° C. from the holding temperature. Therefore, the conveyance time setting unit 60 has the information that the temperature of the molten metal 40 is lowered by about 20 ° C. from the holding temperature in the process of pumping in the first ladle 52a and transferring to the second ladle 52b, and the furnace acquired in step S103. The transport time of the second ladle 52b is set based on the molten metal temperature data, the temperature decrease rate data, and the specified temperature range data.

In this second molten metal supply method, as in the first molten metal supply method, the liquidus temperature of the molten metal 40 is Ta (° C.), the molten metal temperature in the furnace is Tb (° C.), the temperature range is Tc (° C.), the second When the temperature when the molten metal 40 supplied by the ladle 52b comes out of the cooling jig 18 is Td (° C.),
Tb>Tc>Ta> Td
And Tb ≧ (Ta + 30 ° C.)
Is set to satisfy.

  Specifically, the molten metal temperature in the furnace was set to the liquidus temperature of the molten metal + 30 ° C. to + 50 ° C., and the specified temperature range was set to the liquidus temperature of the molten metal 40 + 10 ° C. to + 20 ° C. Further, regardless of the material of the first ladle 52a, a ladle having a temperature decrease rate of 0.1 to 3.0 ° C./second is used as the second ladle 52b. Therefore, the conveyance time of the second ladle 52b is set within a range shown in Table 2 below, for example. Thereby, the supply temperature (pouring temperature) to the cooling jig 18 can be set within the range of the liquidus temperature of the molten metal + 10 ° C. to 20 ° C. The example shown in Table 2 is merely a representative example.

  Thereafter, in step S105, the ladle transport control unit 62 controls the ladle transport mechanism 56 based on the set transport time to transport the second ladle 52b. In the transport of the second ladle 52b, the transport time measuring unit 64 counts the time from the start of transport of the second ladle 52b by the ladle transport mechanism 56 to the end of transport of the second ladle 52b.

  After that, in step S106, the molten metal temperature calculation unit 66 says that the molten metal temperature decreases by about 20 ° C. from the holding temperature in the process of the molten metal temperature data in the furnace, pumping in the first ladle 52a, and transferring to the second ladle 52b. Based on the information, the temperature decrease rate data, and the measured transport time, the temperature of the molten metal 40 in the second ladle 52b when the second ladle 52b reaches the upper end of the cooling jig 18 (in the second ladle) Calculate the molten metal temperature.

  Thereafter, in step S107, the determination unit 68 determines whether or not the molten metal temperature in the second ladle calculated by the molten metal temperature calculation unit 66 is within a specified temperature range.

  If the molten metal temperature in the second ladle is within the specified temperature range, the process proceeds to step S108, and the molten metal supply / discharge control unit 70 controls the second ladle driving unit 54b to control the molten metal in the second ladle 52b. The molten metal 40 is supplied from the upper end of the cooling jig 18.

  On the other hand, when the molten metal temperature in the second ladle is not within the specified temperature range, the process proceeds to step S109, and the molten metal supply / discharge control unit 70 controls the second ladle driving unit 54b to store the molten metal in the second ladle 52b. The molten metal 40 is discarded (steel) without being supplied to the cooling jig 18.

  Thereafter, in step S110, it is determined whether or not there is an end request for the molten metal supply process. If there is no end request, the process returns to step S101 and subsequent steps (continuous operation). In step S110, when there is an end request, the processing by the second molten metal supply method ends.

  Thus, also in the second molten metal supply method, the supply temperature (pour temperature) to the cooling jig 18 is controlled at the liquidus temperature of the molten metal + 10 ° C. to 20 ° C. Thus, the frequency of crystal nucleation in the semi-solidified metal can be improved without the need for additional additives, and a fine and spherical semi-solid metal can be obtained. Moreover, since only one molten metal holding furnace 50 is required, space saving, energy saving, and low cost can be promoted. Since the holding temperature of the molten metal holding furnace 50 is controlled at the liquidus temperature of the molten metal + 30 ° C. to 50 ° C., when the molten metal is pumped from the molten metal holding furnace 50 using the first ladle 52a, the first ladle is used. Solidified metal does not adhere to 52a. As the second ladle 52b, a ladle having a temperature decrease rate of 0.1 to 3.0 ° C./second is used, and the conveyance time of the second ladle 52b is set to the degree of the temperature decrease of the molten metal 40 immediately after being pumped to the first ladle 52a. The temperature of the molten metal 40 immediately after being transferred to the second ladle 52b is set according to the degree of temperature decrease and the temperature decrease rate of the ladle 52 to be used. Temperature) can be in the range of the liquidus temperature of the molten metal + 10 ° C to 20 ° C. Since the conveyance time of the second ladle 52b is set based on the holding temperature of the molten metal holding furnace 50 and the like, and the pouring temperature to the cooling jig 18 is controlled, it is stable regardless of the holding temperature variation. Thus, a desired semi-solid metal slurry 74 can be obtained. Further, it is possible to avoid an unexpected situation in which molten metal 40 outside the specified temperature range is poured into the cooling jig 18.

  In particular, in this second molten metal supply method, instead of waiting for the molten metal temperature to fall naturally in the ladle, the molten metal 40 pumped by the first ladle 52a is transferred to the second ladle 52b in the middle. As a result, the molten metal 40 can be actively cooled, and the cycle time can be shortened.

  By the first molten metal supply method using the first semi-solid metal casting apparatus 10A, the molten metal 40 pumped from the molten metal holding furnace was supplied to the cooling jig 18 to generate the semi-solid metal slurry 74.

  As the molten metal 40, 35 kg of an aluminum alloy (AC2B alloy) was used. The liquidus temperature of the molten metal 40 is 604 ° C.

  The temperature of the molten metal 40 in the molten metal holding furnace 50 was maintained at the liquidus temperature of the molten metal 40 + 30 ° C. As the ladle 52, a ladle having a temperature decrease rate of 0.7 to 0.8 ° C./second with respect to the molten metal 40 was used. As the cooling jig 18, a cooling jig having a flow length of 950 mm, a width of the flow groove 46 of 120 mm, and a side wall height of the flow groove 46 of 120 mm was used.

  And it is discharged from the cooling jig 18 when the pouring temperature to the cooling jig 18 is + 0 ° C., + 2 ° C., + 10 ° C., + 20 ° C., + 30 ° C., + 40 ° C. with respect to the liquidus temperature. The temperature of the molten metal immediately after (the exit temperature of the cooling jig) was measured. The result is shown in FIG.

  From the result of FIG. 6, it can be seen that the semi-solid metal slurry 74 cannot be obtained unless the temperature of pouring to the cooling jig 18 is set to the liquidus temperature + 20 ° C. or lower.

  On the other hand, the lower limit of the pouring temperature is, as described above, when the liquidus temperature of the molten metal 40 is less than + 10 ° C., during the continuous operation, the metal of the molten metal for reasons such as the distribution of molten metal to the molten metal holding furnace 50. If the components vary and the liquidus temperature changes, the pouring temperature to the cooling jig 18 may be lower than the liquidus temperature. FIG. 7 shows the relationship between the solid phase ratio and temperature of the molten metal 40 used in the example. The liquidus temperature when the metal component of the molten metal 40 is set to the lower limit (the temperature when the solid fraction is 0%) is 612 ° C., and the liquidus temperature when the metal component of the molten metal 40 is set to the upper limit is 604. It has a variation of 8 ° C. Therefore, the lower limit of the pouring temperature is preferably the liquidus temperature of the molten metal + 10 ° C. in consideration of the upper and lower limits of the metal component of the molten metal 40.

  From this, as shown in FIG. 6, if the pouring temperature to the cooling jig 18 is in the range of the liquidus temperature + 10 ° C. to + 20 ° C., the cooling is good and the desired solid phase ratio is obtained. When a semi-solid metal slurry is obtained and the pouring temperature to the cooling jig 18 is in the range exceeding the liquidus temperature + 20 ° C., it is found that the cooling is poor.

  In addition, the molten metal supply method in the semi-solid metal casting according to the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10A ... 1st semi-solid metal casting apparatus 10B ... 2nd semi-solid metal casting apparatus 12 ... Metal mold | dies 22 ... Supply control part 52 ... Ladle 52a ... 1st ladle 52b ... 2nd ladle 54 ... Ladle drive part 54a ... 1st ladle Drive unit 54b ... second ladle drive unit 56 ... ladle conveyance mechanism 58 ... molten metal pumping control unit 60 ... conveyance time setting unit 62 ... ladle conveyance control unit 64 ... conveyance time timing unit 66 ... molten metal temperature calculation unit 68 ... determination unit 70 ... Molten metal supply / discharge control unit

Claims (3)

A semi-solid metal slurry is obtained by supplying molten metal to the injection sleeve via a cooling jig, and then the semi-solid metal slurry is injection-molded into a mold cavity to form a cast product. In the molten metal supply method in solid metal casting,
A process of pumping the molten metal in the molten metal holding furnace with a ladle;
Cooling the molten metal in the ladle to a specified temperature range;
Supplying the molten metal, which has been lowered to the prescribed temperature range in the ladle, to the injection sleeve via the cooling jig,
The liquidus temperature of the molten metal is Ta (° C.), the temperature of the molten metal in the molten metal holding furnace is Tb (° C.), the specified temperature range is Tc (° C.), and is discharged from the cooling jig. When the temperature of the molten metal is Td (° C.)
Tb>Tc>Ta> Td
And Tb ≧ (Ta + 30 ° C.)
A molten metal supply method in semi-solid metal casting characterized by satisfying In the molten metal supply method in the semi-solid metal casting according to claim 1,
The temperature of the molten metal in the molten metal holding furnace ranges from + 30 ° C. to + 50 ° C. with respect to the liquidus temperature of the molten metal,
The specified temperature range is a range of + 10 ° C. to + 20 ° C. with respect to a liquidus temperature of the molten metal, and a molten metal supply method in semi-solid metal casting. In the molten metal supply method in the semi-solid metal casting according to claim 1,
The step of cooling the molten metal to a specified temperature range in the ladle is characterized in that the molten metal is cooled by transferring the molten metal from the ladle pumped out of the molten metal holding furnace to another ladle. A molten metal supply method in semi-solid metal casting.

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