JP2005349396A - Injection molding method for semi-solidified metal slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique, with which the unevenness of stirring time performed for fixing the solidified ratio of molten metal can be restrained, in the injection molding of semi-solidified metal slurry. <P>SOLUTION: This technique is performed by passing through the following processes, that is, ST19: a crucible is cleaned, ST20: this cleaning is performed at any number of times till completing the cleaning, ST21: coating is applied to the crucible, ST22: the temperature T1 of the crucible is read, ST23: the temperature T2 of a molten metal holding furnace is read, ST24: cooling time t is decided from the temperature T1 of the crucible, the temperature T2 of the molten metal holding furnace and a correlation diagram, ST25: the cooling of the crucible is started, and ST26: when the time reaches t, the cooling is completed. In this way, the unevenness of the stirring time can be restrained and the productivity in this injection molding of the semi-solidified metal slurry can remarkably be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in injection molding technology of semi-solid metal slurry.

Conventionally, the injection molding technique of a semi-solid metal slurry is known (for example, refer patent document 1).
JP 2002-336946 A (FIG. 12)

Patent document 1 is demonstrated based on the following figure.
FIG. 14 is a basic flowchart of the prior art.
S1 (step 1): Receive a single hot water supply to the ladle from the molten metal holding furnace.
S2 (Step 2): The ladle is transported to the stirring station where it is transferred to the first container.
S3 (step 3): The molten metal in the first container is stirred at the stirring station to obtain a desired solid phase ratio as a solid-liquid coexistence state. At this time, the temperature is uniform.

S4 (Step 4): Transport the first container to the injection molding mechanism.
S5 (Step 5): On the other hand, the injection molding mechanism performs mold clamping in parallel.
S6 (Step 6): Hot water is poured from the first container into the injection sleeve.

S7 (Step 7): Injection into the mold.
S8 (Step 8): Air blow is performed on the empty first container.
S9 (step 9): The first container is cleaned by brushing.

S10 (Step 10): Coating is applied to the first container.
S11 (Step 11): If the number of manufactured molded articles has reached a predetermined number, the manufacturing ends. If not, return to S1 and continue production.

  By the way, since a semi-solid metal slurry is a mixture of a solid phase and a liquid phase, management of the solid phase ratio (= solid phase / (liquid phase + solid phase)%) is important. This is because the quality of the obtained molded product changes when the solid phase ratio is different.

In recent years, as a technique for managing the solid phase ratio, a method of managing by the viscosity has been developed. That is, it is based on a solid phase ratio-viscosity correlation rule that the viscosity increases as the solid phase ratio increases. Then, in S3 (step 3) of the previous figure, the molten metal in the first container is cooled and stirred with gold, but the cooling proceeds due to the heat removal effect accompanying this stirring, the viscosity of the molten metal is increased, and the solid phase ratio is increased. Rise.
Accordingly, a solid phase ratio management method using stirring, in which the target viscosity is determined from the target solid phase ratio and stirring is performed until the target viscosity is reached, is being adopted.

However, when the above-described conventional technique was used to obtain a plurality of molded articles so as to obtain a constant viscosity, the required stirring time varied greatly.
If the agitation time is extremely long, the injection molding mechanism must be waited, resulting in reduced productivity. In addition, if the stirring time is extremely short, the injection molding mechanism will not be in time, so it is necessary to limit the number of containers to be circulated, resulting in a decrease in productivity.

  That is, in order to properly circulate a plurality of containers and operate the injection molding mechanism satisfactorily, it is necessary to reduce the variation in the stirring time.

  This invention makes it a subject to provide the technique which can suppress the dispersion | variation in the stirring time implemented in order to make the solid-phase rate of a molten metal constant in the injection molding of a semi-solid metal slurry.

While investigating the cause of the variation in the stirring time, the present inventors generate a time difference in the brushing process in S9 (step 9) in FIG. 14, and the amount of heat released into the atmosphere increases with time. Attention was paid to the unstable temperature of the container. That is, there are various forms of the residue attached to the empty container, and one that can be easily cleaned at a time and one that requires a plurality of times of cleaning appear.
Then, after carrying out cleaning and coating, it came to be considered that it is beneficial to make the temperature of the molten metal container constant by cooling and making the temperature after cooling constant.

Furthermore, the inventors also noted that the temperature of the molten metal supplied from the molten metal holding furnace changes in S1 (step 1) of FIG.
There is a variation in the temperature of the molten metal supplied from the aluminum melting furnace, and this variation in temperature affects the molten metal holding furnace, and the temperature of the molten metal supplied from the molten metal holding furnace also varies.
If the temperature of the molten metal container is constant and there is a variation in the temperature of the molten metal, it will appear as a variation in the stirring time.

In order to make the temperature of the molten metal supplied from the molten metal holding furnace constant, it is conceivable to provide a high-performance temperature control mechanism in the molten metal holding furnace, but it is difficult to realize technically and costly.
That is, a technique capable of absorbing fluctuations in the molten metal supplied from the molten metal holding furnace is required.

Therefore, the inventors have increased the cooling time of the molten metal container if the temperature of the molten metal holding furnace is high, and shortened the cooling time of the molten metal container if the temperature is low. I came up with the idea of passing on the temperature of the molten metal container.
Then, when the cooling time of the molten metal temperature was determined in consideration of both the temperature of the empty molten metal container and the temperature of the molten metal holding furnace, the variation width of the stirring time was successfully reduced. From the above knowledge, the invention is summarized as follows.

  According to the first aspect of the present invention, a molten metal container that has been emptied by pouring a semi-solid metal slurry into an injection molding mechanism is cooled for a predetermined time in preparation for the next molten metal, and the molten metal holding furnace is supplied to the cooled molten metal container. In the semi-solid metal slurry injection molding method in which the supply of the semi-solid metal slurry is repeated, the predetermined time when the empty molten metal container is cooled for the next pouring is determined by the temperature of the molten metal holding furnace and the empty molten metal. It is determined based on the temperature of the container.

  When the temperature of the molten metal holding furnace is high, the required time is extended, and when the temperature is low, the required time is shortened. In addition, the required time is extended when the temperature of the empty container is high, and the required time is shortened when the temperature is low.

  In the invention according to claim 1, since the empty molten metal container is cooled in the required time determined based on the temperature of the molten metal holding furnace and the temperature of the empty molten metal container, it is possible to suppress variation in the stirring time. The productivity in injection molding of semi-solid metal slurry can be greatly increased.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a layout diagram of a semi-solid metal slurry injection molding facility according to the present invention. A semi-solid metal slurry injection molding facility 10 includes a molten metal holding furnace 11 for maintaining a metal at a temperature higher than the melting point, and the molten metal holding furnace. The ladle 12 to which the molten metal for one time is supplied from 11, the first robot 14 for transporting the ladle 12 to the central base 13, the molten metal container 15 placed on the central base 13, and the molten metal in the molten metal container 15 are stirred. Agitating means 30 (details will be described later), a stirrer restoring base 17 for removing the molten metal adhering to the agitating means 30 and restoring, and stirring between the stirrer restoring base 17 and the central stage 13 The second robot 18 for reciprocating the means 30, the injection molding mechanism 20 having the injection sleeve 19, the third robot 21 for transporting the molten metal container 15 to the injection sleeve 19, and the empty molten metal container 15 are cleaned. And, a maintenance platform 22 to be coated, the cooling stage 24 having an air blow nozzle 23 for cooling the molten metal container 15 was cleaned and coated, consisting heating table 25 for heating the molten metal container 15 at the start of operation.

  The molten metal container 15 is preferably a heat-resistant steel cast steel product. For example, SCH12 is a cast stainless steel containing 8 to 12% Ni and 18 to 23% Cr, and has high heat resistance. Although detailed data is omitted, a life (shot) of about 6 times that of a normal carbon steel (SS400-JIS) container was obtained.

Moreover, the thermal conductivity of carbon steel is 60.7 W / m · K, whereas the thermal conductivity of SCH12 is 14.7 W / m · K.
When the thermal conductivity of the container is large, the end of the melt (the part in contact with the container) becomes considerably low with respect to the center of the melt, and a temperature difference occurs in the melt.
In this regard, the SCH12 container has a small thermal conductivity and a small temperature difference between the center and the end of the molten metal. That is, there is an advantage that the temperature of the molten metal is easily uniform and temperature management is simplified.

The operation of the injection molding equipment 10 having the above configuration will be described.
FIG. 2 is an operation diagram of the ladle. The ladle 12 pumps the molten metal from the molten metal holding furnace 11 and pours it into the molten metal container 15 placed on the central table 13. The temperature T2 of the molten metal holding furnace 11 is measured by the temperature sensor 26.

  FIG. 3 is an operation diagram of the agitation means. The agitation means 30 placed on the agitator restoring table 17 is moved to the central stage 13 where the molten metal in the molten metal container 15 is agitated. return.

  FIG. 4 is a principle diagram of the agitating means. The agitating means 30 includes cooling metal type agitators 31 and 32, a cantilever-shaped measuring element 33, and a measuring element movement for moving the measuring element 33 in the horizontal direction. Means 34, a load cell 35 for measuring the force received by the measuring element 33, a fixed part 36 for fixing the load cell 35, a force conversion means 37 for converting the physical quantity from the load cell 35, and a viscosity conversion means 38. It is a structure comprising the force-viscosity conversion means 39 provided.

  In the semi-solid metal slurry 40 filled in the molten metal container 15, the stirring means 30 is moved by the cooling metal stirrers 31 and 32 and the measuring element 33 is moved in the horizontal direction by the measuring element moving means 34. Thus, the force received by the cooling metal stirrers 31 and 32 and the measuring bar 33 from the semi-solid metal slurry 40 is recognized by the load cell 35 as, for example, the strain voltage V1, and then the viscosity B is determined by the force-viscosity conversion means 39. It is a device to seek.

  FIG. 5 is a view taken in the direction of arrow 5-5 in FIG. 4. The cooling metal stirrers 31 and 32 are provided with a measuring bar 33 therebetween, and the inside of the semi-solid metal slurry 40 filled in the molten metal container 15 is indicated by an arrow. It moves to a rectangle, stirs the semi-solid metal slurry 40, deprives heat and cools.

  FIG. 6 is a graph showing the correlation between the solid phase rate and the viscosity. The horizontal axis represents the solid phase rate and the vertical axis represents the viscosity, and a curve R rising to the right can be drawn there. If this curve R is prepared for each type of alloy, the target viscosity A can be obtained in the following manner.

  For example, the target solid phase rate of the aluminum alloy molten metal, which is the aluminum alloy die casting raw material shown on the horizontal axis, is determined, the intersection (1) extending vertically upward from the target solid phase rate is obtained on the graph, and the viscosity is calculated from the intersection point. The point (2) extending perpendicularly to the axis is extended to determine the point at which the line intersects the viscosity axis as the target viscosity A.

  Preparing a correlation graph showing the correlation between the solid phase ratio and the viscosity of the semi-solid metal slurry for each metal component can determine the target viscosity corresponding to the target solid phase ratio in advance, and can smoothly proceed with the subsequent steps. .

  FIG. 7 is a graph showing the correlation between the strain voltage and the viscosity. Using the means described in FIGS. 4 and 5, the strain voltage for a fluid having a known viscosity is measured, and the measured value (x mark) is plotted. The curve S was obtained. If this curve S is present, the viscosity B at that time can be obtained from the measured value (strain voltage) in the following manner.

  The strain voltage measured by the load cell is taken on the horizontal axis, and the intersection point on the graph and the line (3) extending vertically upward from the measured strain voltage is obtained, and the line (4) perpendicular to the viscosity axis is extended from the intersection point to increase the viscosity. The point that intersects the axis is determined as the viscosity B.

  A database corresponding to FIGS. 6 and 7 is constructed in advance. Then, the target viscosity is obtained from the target solid phase ratio, and the strain voltage is obtained from the target viscosity. Then, the molten metal in the molten metal container is stirred until this strain voltage is reached. Thus, a molten metal having a target solid phase ratio can be provided.

FIG. 8 is an operation diagram of the molten metal container. The molten metal container 15 with the target solid phase ratio adjusted is moved to the injection sleeve 19 and poured into the injection sleeve 19.
FIG. 9 is an operation diagram of an empty pouring container. The emptied molten metal container 15 is transferred to the maintenance table 22 where the residue is removed and then the coating is applied. At that stage, the temperature sensor 27 measures the temperature T1 of the molten metal container 15.
The molten metal container 15 is moved to the cooling table 24, where air is ejected from the air blow nozzle 23 and air cooling is performed for a predetermined time. When cooling is completed, the molten metal container 15 is returned to the central stage 13.

  Next, a correlation diagram showing the relationship between the temperature of the molten metal container, the temperature of the molten metal holding furnace, and the air blowing time is created. The following figure shows an example of the created correlation diagram.

FIG. 10 is a correlation graph of the temperature of the molten metal container-temperature of the molten metal holding furnace-air blow time according to the present invention.
Explaining how to use this correlation graph, if the temperature of the molten metal container measured during the production is Rt2 and the temperature of the molten metal holding furnace is Ft2, the air blow time to be set is Tab2.

  If the air is blown for Tab 2 hours, the molten metal container is returned to the central stage, the molten metal is supplied to the molten metal container, and stirred by the stirring means, the stirring time until the viscosity becomes constant is almost constant.

A manufacturing flow using the above correlation graph will be described next.
FIG. 11 is a manufacturing flow chart until injection, and STxx indicates a step number.
The molten metal container is described with the name “crucible”.

ST11: Since the crucible is at room temperature for the first time, it is necessary to heat to a predetermined initial temperature. In order to check whether or not the crucible is the first time, it is checked whether or not the crucible temperature is 100 ° C. or less. If it exceeds 100 ° C., it is considered that heating is not necessary, and the process proceeds to ST13.
ST12: When the temperature is 100 ° C. or lower in ST11, the crucible is heated to the initial temperature.
ST13: Place the crucible on the center base.

ST14: The molten metal is pumped out from the molten metal holding furnace with a ladle.
ST15: Supply molten metal to the crucible.
ST16: The solid phase ratio of the molten metal is immediately prepared.
ST17: The prepared molten metal is poured into the injection sleeve.
ST18: Injection is performed to obtain a molded product.

FIG. 12 is a manufacturing flowchart until the crucible cooling.
ST19: Clean the crucible.
ST20: Repeatedly until cleaning is completed.
ST21: The crucible is coated.

ST22: The crucible temperature T1 (corresponding to Rt2 in FIG. 10) is read.
ST23: The temperature T2 (corresponding to Ft2 in FIG. 10) of the molten metal holding furnace is read.
ST24: The cooling time t (corresponding to Tab2 in FIG. 10) is determined from the crucible temperature T1, the molten metal holding furnace temperature T2 and the correlation diagram (see FIG. 10).
ST25: Start cooling of the crucible.
ST21: Cooling is completed when time reaches t.

FIG. 13 is a graph for explaining the effect of the present invention, in which the horizontal axis represents the stirring time and the vertical axis represents the frequency.
Although detailed explanation is omitted, in the conventional technique, the variation in the stirring time was D. On the other hand, according to the present invention, the variation in the stirring time was 0.4 × D, that is, 40% of the conventional value.
Therefore, according to the present invention, it can be said that the variation in the stirring time can be greatly improved.

The correlation graph described in the embodiment (the temperature of the molten metal container—the temperature of the molten metal holding furnace—the correlation graph of the air blowing time) may be a mathematical correlation formula or a tabulated correlation correlation diagram, and the format is arbitrary. Therefore, it is called a correlation diagram.
Further, the method of creating the correlation diagram is not limited to the embodiment.

  The present invention is suitable for the semi-solid metal slurry injection molding technique.

It is a layout figure of the injection molding equipment of the semi-solid metal slurry which concerns on this invention. It is an action figure of a ladle. It is an effect | action figure of a stirring means. It is a principle diagram of a stirring means. It is a 5-5 arrow line view of FIG. It is a graph showing the correlation with a solid-phase rate and a viscosity. It is a graph showing the correlation between a strain voltage and a viscosity. It is an effect | action figure of a molten metal container. It is an effect | action figure of an empty pouring container. It is a correlation graph of the temperature of the molten metal container which concerns on this invention-the temperature of a molten metal holding furnace-air blow time. It is a manufacturing flowchart until injection. It is a manufacturing flowchart until crucible cooling. It is a graph for demonstrating the effect of this invention. It is a basic flowchart of a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Injection molding equipment of semi-solid metal slurry, 11 ... Molten metal holding furnace, 15 ... Molten metal container (crucible), 20 ... Injection molding mechanism, 23 ... Air blow nozzle, 24 ... Cooling stand, 26, 27 ... Temperature sensor, 40 ... Semi-solid metal slurry.

Claims (1)

The molten metal container that has been emptied by pouring the semi-solid metal slurry into the injection molding mechanism is cooled for a predetermined time in preparation for the next pouring, and the semi-solid metal slurry is supplied to the cooled molten metal container from the molten metal holding furnace. In the semi-solid metal slurry injection molding method that repeats,
The predetermined time when the empty molten vessel is cooled for the next pouring is determined based on the temperature of the molten metal holding furnace and the temperature of the empty molten vessel. Molding method.

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