JP2009248119A - Die for molding semi-molten metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for molding semi-molten metal configured to prevent the product defect caused by the cold shut and residual gas of the semi-molten metal by controlling the fluidity in an annular part by using a simple configuration. <P>SOLUTION: In the die for molding the semi-molten metal, the semi-molten metal is filled into the annular part having a wall thickness change and an overflow is formed at a merging part of the semi-molten metal generated when the semi-molten metal is filled. The overflow is provided so as to be divided into several overflow parts in an axial line direction of the annular part, for changing the molten metal flow direction to prevent the product defect. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold for forming a semi-molten metal, and in particular, has an annular portion as a bearing portion in a molded product, and prevents a hot water boundary that occurs when the semi-molten metal merges in the annular portion. The present invention relates to a mold for forming a semi-molten metal so as to obtain a molded product.

  The semi-molten metal molding method, also called the thixocast method, is a method for obtaining a molded product by press-filling a light metal such as aluminum, magnesium or an aluminum alloy into a mold cavity in a semi-molten state.

  However, in the method of forming a semi-molten metal, the temperature of the molten metal at the time of forming is lower than that of the conventional die casting method, so that a hot water boundary including gas defects or the like is likely to occur at the junction of the semi-molten metal. Have a problem. This hot water boundary is particularly likely to occur when the molded product has a complicated shape, for example, when it has a part where the semi-molten metals merge and become integrated in the cavity. There is a problem that the quality is inevitably deteriorated because it is significantly reduced.

  For example, Patent Document 1 discloses that the length of the annular portion is wide in the opening / closing direction of the mold, shallow in the direction intersecting the opening / closing direction, through the connecting passage to the opposite position sandwiching the junction where the hot water boundary is generated from the outside. A semi-molten metal forming mold has been proposed in which an overflow portion is disposed so as to substantially match and a molten metal flows into the overflow portion to prevent defects in the molded product. However, the center hole of the annular part is formed with a core pin, and the annular part has a thickness that is not uniform and the thickness is changing. When configured, the filling of the overflow portion is completed first, and the hot water boundary cannot be discharged to the overflow portion, so that deterioration in quality cannot be avoided.

  FIG. 6 is a schematic view of the cavity portion of a conventional mold for forming a semi-molten metal having an overflow provided in the axial direction of the annular portion. As shown in FIG. 6, the axis of the annular portion 102 is set to a direction intersecting with the opening / closing direction of the mold, and the center hole of the annular portion is formed by the core pin 126. Since the core pin 126 has a draft angle, the cross-sectional area and the thickness of the annular portion 102 in the core pin insertion direction change in the axial direction. An overflow portion 108 constituted by the overflow gate 103 and the overflow 105 is configured to substantially coincide with the length of the annular portion 102.

FIG. 7 is a conceptual diagram showing the behavior when the cavity portion 100 shown in FIG. 6 is pressurized and filled with a semi-molten metal. The behavior of the semi-molten metal will be described with reference to FIG. The semi-molten metal that has flowed into the annular portion 102 of the mold cavity advances while gradually flowing into the overflow 105 from the annular portion 102 and the thick wall side as shown in FIG. As described above, the cross-sectional area of the annular portion 102 changes with respect to the insertion direction of the core pin 126. For this reason, as shown in FIG. 7 (2), the semi-molten metal filled in the mold cavity flows preferentially on the thick side, and the overflow 105 is completely filled first. Next, as shown in FIG. 7 (3), the filling is completed without discharging the joining portion J of the semi-molten metal that is the hot metal on the thin side to the overflow 105.
As described above, when molding is performed using a conventional mold for forming a semi-molten metal, the hot water boundary Y is left behind in the thin portion of the molded product, so that the quality is deteriorated. The arrows shown in FIG. 7 indicate the behavior when the semi-molten metal is pressure-filled. In addition, the hot water boundary Y is generated at the merging portion at the final filling position.

JP 2004-74270 A

  The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to prevent a defect of a molded product due to a molten metal boundary or residual gas with a simple structure. It aims at providing the metal mold | die for molten metal shaping | molding.

  In order to solve such a problem, in the first invention according to the present invention, an annular part having a change in thickness is filled with a semi-molten metal, and an overflow occurs in the joining part of the semi-molten metal generated when the filling is performed. A mold for forming a semi-molten metal, wherein the overflow is divided into a plurality of parts in the axial direction of the annular portion.

  According to a second aspect of the invention based on the first aspect, the plurality of overflows provided separately are provided with air vents independently of each other.

  According to the mold for forming a semi-molten metal according to the present invention, the overflow is formed in a direction in which the thickness of the molded product changes and is divided into a plurality of merged portions of the semi-molten metal. The boundary can be discharged to the overflow, and the molded product with high mechanical strength is stabilized by preventing the defect of the molded product due to the hot water boundary and gas residue regardless of the change in the wall thickness of the annular part. Can be manufactured.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic view of a cavity portion of a mold for forming a semi-molten metal in which an overflow according to the present invention is disposed at a position coincident with the axial direction of the annular portion, and FIG. 2 is an explanation for explaining the behavior of the semi-molten metal. FIG. 3 is a cross-sectional view of the main part of the mold in which the overflow is disposed at a position coinciding with the axial direction of the annular portion. FIG. 4 is an explanatory view illustrating the dimensional configuration of the overflow portion. FIG. 5 is a schematic view of a cavity portion of a mold for forming a semi-molten metal in which an overflow according to another embodiment of the present invention is disposed at a position coinciding with the axial direction of the annular portion.

The structure of the mold for forming a semi-molten metal will be described with reference to FIGS. Reference numeral 1 denotes a cavity portion of the molded product, and 8 denotes an overflow portion. The overflow unit 8 includes a first overflow gate 3, a first overflow 5, a second overflow gate 13, and a second overflow 15.
The cavity part 1 has a structure in which an annular part 2 is formed at the end part of the molded product main body part, and an overflow part 8 is provided in the axial direction of the annular part 2 that becomes the final filling position when the molten metal is pressurized and filled. It has become. Reference numeral 26 denotes a core pin that forms a central hole of the annular portion 2, and is configured to be moved forward and backward in the axial direction by the driving means 25.

As shown in FIG. 1, the first overflow gate 3 and the second overflow gate 13 are connected between the annular portion 2 of the cavity portion 1 and the first overflow 5 and the second overflow 15, respectively. The gate cross-sectional area of the first overflow gate 3 and the second overflow gate 13 is formed by overlapping the overflow on the overflow gate, so the opening area on the overflow side is set larger than the opening area on the molded product cavity side. It has a configuration.
The overflows 5 and 15 are divided and provided in the axial direction of the annular portion 2, that is, in the direction in which the wall thickness changes due to the escape gradient of the core pin.

As shown in FIG. 3, the semi-molten metal forming die 10 includes a fixed die 20 and a movable die 30, and the inside of both the dies 20 and 30 corresponds to the shape of the molded product. A cavity portion 1 is formed.
At the lower end portions of the fixed mold 20 and the movable mold 30, a tiltable injection device 34 for pressurizing and filling the semi-molten metal M into the cavity portion 1 is provided. Between the injection device 34 and the cavity portion 1, an injection sleeve 36 loaded with a semi-molten metal M from a holding container is brought into contact with the lower end portions of the fixed mold 20 and the movable mold 30 so as to be in the cavity portion 1. An injection port 32 is provided for pressure filling.

Reference numeral 25 denotes a driving means for the core pin 26, and a fluid pressure cylinder is used for driving. Reference numeral 38 denotes an injection plunger rod for pressurizing and filling the cavity 1 formed with a semi-molten metal M in a mold.
Reference numerals 6 and 16 denote air vents for degassing provided in the first overflow 5 and the second overflow 15, respectively. Residual gas in the mold cavity is discharged out of the mold from the gas vent as the semi-molten metal is filled.

Next, a semi-molten metal forming method using the semi-molten metal forming die 10 will be described with reference to FIG.
First, a method for producing a semi-molten metal will be described. From the ladle of the hot water supply means, a holding and holding container having a material with a thermal conductivity of not less than 1 kcal / m · hr · ° C. (not shown) contains a crystal nucleus promoting element that has a superheat degree of less than 50 ° C. with respect to the liquidus. After the molten aluminum alloy in a solid-liquid coexistence state above the forming temperature including crystal nuclei is poured directly without using a jig, the cooling air is blown from the outside of the holding container. Cooling is performed so that the temperature of the molten aluminum alloy is uniform.

  The liquid phase ratio suitable for molding is cooled to the molding temperature and held for 30 seconds to 30 minutes, so that a fine primary crystal is crystallized in the molten metal by an induction device (heating coil) in the holding container. The temperature of each part of the molten aluminum alloy is adjusted so as to be within a target forming temperature range (600 ° C. in the present embodiment) showing a predetermined liquid phase ratio before forming at the latest.

Note that the amount of the finer added to obtain fine spherical crystals is small when Ti alone is added. If the amount is less than 0.03%, the effect of refining is small, and if it exceeds 0.3%, a coarse Ti compound Is generated and the ductility is lowered, so Ti is made 0.03% to 0.3%.
In Ti and B composite addition, if Ti is less than 0.005%, the effect of miniaturization is small, and if it exceeds 0.3%, a coarse Ti compound is generated and ductility is lowered. 0.3%. B promotes miniaturization in combination with Ti, but if less than 0.001%, the effect of miniaturization is small, and even if added over 0.01%, no further effect can be expected. Is 0.001% to 0.01%.

As shown in FIG. 3, when the molten metal reaches a target uniform temperature in the holding container, the completed semi-molten metal M is filled into the injection sleeve 36 of the injection device 34. When the semi-molten metal M is filled into the injection sleeve 36 of the injection device 34, the mold 10 is already closed. A cavity 1 is formed between the fixed mold 20 and the movable mold 30.
When the injection filling operation is performed, the injection plunger rod 38 of the injection device 34 moves forward, and the cavity portion 1 starts to be filled with the semi-molten metal M. As the injection plunger rod 38 advances, the semi-molten metal M fills the cavity portion 1 while flowing, and the flowing semi-molten metal M at the leading end eventually reaches the inlet of the annular portion 2.

As shown in FIG. 2 (1), the semi-molten metal M that has reached the inlet of the annular portion 2 branches to the left and right according to the shape of the annular portion 2, and then gradually turns the annular portion 2 clockwise and counterclockwise. Flows in the direction of rotation. The annular portion 2 has a different thickness in the axial direction, and the front end portion of the semi-molten metal M fills the annular portion 2 and also from the first overflow gate 3 provided on the thick side, the first overflow. 5 and the first overflow 5 is completely filled.
The tip of the anti-molten metal M flowing through the annular portion 2 joins the tip on the thin side. The temperature of the semi-molten metal M flowing at the tip is lowered when flowing through the cavity 1, and even if the tips of the semi-molten metal M whose temperature is lowered join each other, they are not completely integrated. Therefore, as shown in FIG. 2 (2), a hot water boundary Y is generated in the joining portion J so as to extend in a direction orthogonal to the flow direction of the semi-molten metal M immediately before joining.

After the hot water boundary Y occurs at the junction J, the semi-molten metal M continues to flow into the second overflow 15 via the second overflow gate 13. At this time, most of the hot water boundary Y is swept away by the semi-molten metal M flowing into the second overflow 15 through the second overflow gate 13 and flows into the second overflow 15. Then, when the second overflow 15 is filled, the filling of the cavity portion 1 is also completed (FIG. 2 (3)).
Although the hot water boundary Y remains on the center hole side of the annular portion, the remaining hot water boundary Y is very small and does not affect the strength of the annular portion. For example, it can be easily excised by cutting or the like.

  When the filling is completed, the molded product is cooled for a predetermined time, and the movable mold 30 is opened in a state where the molded product remains in the movable mold 30 after the cooling is completed. Next, the extrusion pin is moved to release the molded product from the movable mold 30. The molded product taken out from the mold 10 becomes the final molded product by cutting and separating the first overflow 5 and the second overflow 15 from the gate portion in the next step.

  Next, the dimensional configuration of the overflow portion 8 will be described with reference to FIG. As described above, the overflow part 8 is divided in the axial direction of the annular part 2 into the joining part J where the semi-molten metal M joins in the annular part 2 of the molded product, and the first overflow 5 and the second overflow 15 are provided. It has a configuration. For this reason, it is possible to remove the hot water boundary Y generated at the joining portion J of the annular portion 2 to the overflow portion 8 so that the hot water boundary Y does not remain in the molded product. As shown in FIG. 4, the thickness of the molded product of the annular portion 2 changes from T1 to T2 in the extraction direction of the core pin.

The cross sections of the first overflow gate 3 and the second overflow gate 13 have a rectangular shape, and their thickness and width are represented by G1xt1 and G2xt2. The cross-sectional area of the overflow gate is set smaller than the cross-sectional area of the molded product in order to smoothly discharge the molten metal Y generated at the junction J of the molded product to the overflow side. The flow speed is increased. The ratio of the cross-sectional area of the molded product flow section and the cross-sectional area of the overflow gate is preferably set in the range of 30% to 70%.
Further, by providing the overflow by wrapping it on the overflow gate, the sectional area on the side flowing into the overflow is made larger than the sectional area on the side flowing out from the molded product.

The widthwise dimensions W1 and W2 of the overflow gates 3 and 13 are divided by the dividing wall S of the gate, and the total dimension is set to be substantially the same as the axial length of the annular portion 2 of the molded product. The dimensions W1 and W2 and G1 and G2, and t1 and t2 of the overflow gates 3 and 13 are preferably set to predetermined dimensions in consideration of the shape of the molded product.
In the present embodiment, the overflow gate is divided by the dividing wall S. However, in the case where the dividing wall prevents discharge of the hot water Y to the overflow, the overflow gate is integrated without providing the dividing wall, May be provided separately.
In this embodiment, one partition wall is provided and two overflows are provided. However, the present invention is not limited to this embodiment, and a configuration in which two or more partition walls and three or more overflow walls are provided is also possible. good. Furthermore, although the widths W1 and W2 in the width direction of the overflow gates 3 and 13 are substantially the same in the axial direction of the annular portion 2, the dimensions W1 and W2 may be set to different dimensions without being limited thereto. good.

  FIG. 5 is a schematic diagram of a cavity portion of a mold for forming a semi-molten metal in which an overflow is disposed at a position coinciding with the axial direction of the annular portion, illustrating another embodiment of the present invention. The basic structure is the same, although the injection method differs from the injection direction by 90 degrees. The present invention is not limited to the combination of the mold clamping direction and the injection direction. By providing an overflow in the annular part, it is possible to prevent a hot water boundary formed in the final filling part of the annular part. it can.

  As described above, in the present invention, in the mold for molding a molded product of a semi-molten metal having an annular portion having a thickness change, while forming an overflow portion in the axial direction of the annular portion where the thickness changes, Since the overflow part is provided in series on the same plane and divided into a plurality of parts, it is possible to prevent defects caused by residual water and gas remaining during the molding of semi-molten metal, and a molded product with high mechanical strength. It can be obtained stably. In addition, since an air vent is provided at each overflow so that the gas in the cavity is easily discharged, the gas in the cavity does not restrict the flow of hot water and does not entrain the gas in the molded product.

It is a cavity part schematic diagram of the mold for semi-molten metal shaping | molding which has arrange | positioned the overflow which concerns on this invention in the position which corresponds to the axial direction of an annular part, (a) is a front view, (b) is a side view. It is explanatory drawing for demonstrating the behavior of the semi-molten metal of this invention. It is principal part sectional drawing of the metal mold | die which arrange | positioned the overflow of this invention in the position which corresponds with the axial direction of a cyclic | annular part, (a) is a side view, (b) is a front view. It is explanatory drawing explaining the dimension structure of the overflow part of this invention, (a) is a front view, (b) is a side view. It is a cavity part schematic diagram of the semi-molten metal forming metal mold | die which arrange | positioned the overflow which is other embodiment of this invention in the position which corresponds to the axial direction of an annular part, (a) is a side view, (b) is a side view. It is a front view. It is a cavity part schematic diagram of the semi-molten metal forming metal mold | die of the structure which provided the overflow in the axial direction of the conventional annular part, (a) is a front view, (b) is a side view. It is a conceptual diagram which shows the behavior at the time of carrying out pressure filling of the semi-molten metal to the conventional cavity part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cavity part 2 Annular part 3 1st overflow gate 5 1st overflow 6 Air vent 8 Overflow part 10 Semi-molten metal shaping die 13 2nd overflow gate 15 2nd overflow 16 Air vent 20 Fixed mold 25 Core pin drive means 26 Core pin 30 Movable mold 32 Inlet 34 Injection device 36 Injection sleeve 38 Injection plunger rod J Semi-molten metal junction M Semi-molten metal S Split wall Y Hot water boundary

Claims (2)

A semi-molten metal forming mold in which an annular portion having a wall thickness change is filled with a semi-molten metal, and an overflow is formed at a joining portion of the semi-molten metal generated when the filling is performed,
A mold for semi-molten metal forming, wherein the overflow is divided into a plurality of parts in the axial direction of the annular portion.   The mold for semi-molten metal forming according to claim 1, wherein each of the overflows divided into a plurality is provided with an air vent independently.

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