JPH10146662A - Die casting method and die casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a pressurizing effect to molten metal filled up in a cavity (product part) in a die casting method for pressurizing the molten metal in a runner part of a die with a pressurizing mechanism after pressing the molten metal into the cavity in the die, and a die casting apparatus. SOLUTION: In the runner part 14 as a passage for passing through the molten metal pressed into the cavity 10 of the dies 2, 4 with an injection sleeve 11 and an injection plunger 12 in an injection mechanism, a weir 19 for preventing the back flow of the molten metal into a position is formed at the upstream side from a pressurizing sleeve 16 and a pressurizing plunger 17 of the pressurizing mechanism. At the time of executing the pressurization to the molten metal with the pressurizing sleeve 16 and pressurizing plunger 17 of the pressurizing mechanism, the pressurization to the molten metal is executed while preventing the back flow into the upstream side of the molten metal with the weir 19. Therefore, such phenomenon that the injection plunger 12 in the injection mechanism is retreated at the time of pressurizing, is not developed and the pressurizing effect (feeder head effect) on the molten metal in the cavity 10 can sufficiently be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for press-fitting a molten metal into a cavity of a die-casting die by an injection mechanism, and then adding the molten metal in a runner portion of the die by a pressing mechanism installed in the die. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting method and a die casting apparatus for applying a pressurizing (pressing) effect to molten metal in a cavity (product part) by pressing.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 64-78664 discloses that after a molten metal is pressed into a mold cavity, the molten metal in a runner portion of the mold is pressurized by a pressurizing mechanism, so that a cavity (product portion) is formed through a gate portion. ) Describes a die casting method in which a pressurizing effect is applied to the molten metal.

[0003]

However, according to the studies by the present inventors, in the above publications, the molten metal in the runner portion is simply pressurized by the pressurizing mechanism. It turned out that a problem like this occurred. That is, in the former JP-A-1-313176, when the molten metal is pressurized by the pressurizing mechanism, when a high pressure (generally, about twice the casting pressure by the injection mechanism) is applied, the injection plunger of the injection mechanism is caused by the high pressure. Retreats, and the pressurizing effect (pressing effect) on the molten metal in the cavity (product part) cannot be sufficiently exerted. As a result, defects due to shrinkage cavities are likely to occur in the die-cast molded product part. There's a problem.

In Japanese Patent Application Laid-Open No. 64-78664, the pressure plunger of the pressure mechanism is disposed so as to always cover the communication port of the runner with a small gap therebetween. When press-fitting and filling the molten metal into the cavity of the mold by the injection mechanism, the molten metal ejected from the minute gap of the communication port directly hits the pressure plunger, so that the sliding part of the pressure plunger is easily burned. As a result, poor sliding of the pressurizing plunger occurs, resulting in insufficient pressurization of the molten metal in the cavity (product part).

In view of the above, the present invention provides a die casting method and a die casting apparatus in which a molten metal is pressed into a mold runner portion by a press mechanism after the molten metal is press-fitted into a mold cavity. It is an object of the present invention to improve the pressurizing effect on the filled molten metal.

[0006]

In order to achieve the above object, the present invention employs the following technical means. That is, according to the first aspect of the present invention, of the runner portion (14) serving as a passage through which the molten metal pressed into the cavity (10) of the mold (2, 4) by the injection mechanism (11, 12) passes.
A backflow preventing weir (19) for molten metal is formed at a position upstream of the pressurizing mechanisms (16, 17), and when the pressurizing mechanism (16, 17) pressurizes the molten metal, the weir (19) is used. ), A die casting method for pressurizing the molten metal while preventing the molten metal from flowing back to the upstream side.

According to the second aspect of the present invention, a mold (2, 4) that can be opened and closed, and a cavity (10) provided inside the mold (2, 4) and forming a product part, The mold (2, 4) is provided inside the mold (2, 4).
0) and a runner portion (14) forming a passage for the molten metal when the molten metal is pressed into the cavity (10), and an injection mechanism (1) for pressing the molten metal into the cavity (10) through the runner portion (14).
1, 12) and a pressurizing mechanism (1) provided in the runner section (14) and pressurizing the molten metal in the runner section (14) after the molten metal is pressed into the cavity (10).
6, 17) and a backflow preventing portion provided at the upstream side of the pressurizing mechanism (16, 17) in the runner portion (14) so as to reduce the cross-sectional area of the passage of the runner portion (14). A weir (19);
When pressurizing the molten metal according to 7), a die casting apparatus that pressurizes the molten metal while preventing a backflow of the molten metal to the upstream side by the weir (19) is characterized.

According to the first and second aspects of the present invention, the weir (1)
The pressurizing mechanism (16, 17) pressurizes the molten metal while preventing the backflow of the molten metal to the upstream side by 9), and at this time, the injection plunger of the injection mechanism retreats as in the prior art at the time of this pressurization. Does not occur, the cavity (10)
Can exert a sufficient pressurizing effect on the molten metal.

According to the first and second aspects of the present invention,
The backflow prevention weir (19) is configured to reduce the cross-sectional area of the passage of the runner part (14), and has a pressure mechanism (1).
The pressurizing plunger (17) moves backward as shown by the solid line in FIG. 1 when the molten metal is press-fitted.
The phenomenon of directly hitting the pressurizing plunger (17) of 7) does not occur, and therefore, the pressurizing mechanism (1) by the direct hit of the molten metal jetted out.
No sliding failure of 6, 17) occurred, and the pressing mechanism (16, 1) was not used.
7) Good pressurizing action on the molten metal can be ensured over a long period of time.

The length of the backflow prevention weir (19) in the flow direction of the molten metal is 10 to 30 mm.
Further, by setting the length of the backflow preventing weir (19) in the direction of flow of the molten metal to 15 to 25 mm as in the invention of claim 4, the effect of pressing the cavity (10) on the molten metal and the cavity (10) It is possible to achieve compatibility with the operation of the molten metal to run.

Note that the reference numerals in parentheses attached to the respective means and the means described in the claims indicate the correspondence with the specific means described in the embodiments described later.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a die casting apparatus according to a first embodiment of the present invention. Reference numeral 1 denotes a fixed support, which supports a fixed mold 2. Reference numeral 3 denotes a movable support, which supports the movable mold 4 via fastening plates 5, 6, and 7.

A fixed nest 8 is disposed in the fixed mold 2, and a movable nest 9 is disposed in the movable support base 3 so as to face the fixed nest 8. A cavity 10 for forming a product portion is formed between the inserts 8 and 9. In addition, a cylindrical injection sleeve 11 is supported below the fixed support 1, and an injection plunger 12 is slidably fitted in the injection sleeve 11. In this example, the injection mechanism is constituted by the injection sleeve 11 and the injection plunger 12.

The injection plunger 12 has an enlarged diameter portion 12a at the tip, and is moved in the injection sleeve 11 in the axial direction (left-right direction in FIG. 1) by a hydraulic drive mechanism (not shown). The position indicates the state where the injection plunger 12 has advanced most in the mold-clamped state, and the two-dot chain line position 12b indicates the state where it has retracted most. An injection port 13 for molten metal is formed near the maximum retreat position of the injection plunger 12 at a position above the injection sleeve 11,
Die casting metal (for example, aluminum alloy, magnesium alloy,
A molten metal such as a zinc alloy is injected by a molten metal injector (not shown).

The space of the injection sleeve 11 on the maximum advance position of the injection plunger 12 communicates with the cavity 10 via a runner section (injection passage) 14 and a gate section 15. Here, the runner portion 14 and the gate portion 15 are formed by a gap between the fixed nest 8 and the movable nest 9 facing each other, and the molten metal in the injection sleeve 11 is removed by the advance of the injection plunger 12.
It is to be pressed in.

The gate 15 narrows the cross-sectional area of the passage of the runner 14 and discharges the molten metal into the cavity 10 at a high speed. A pressure sleeve 16 is disposed in the runner portion 14 at a position upstream of the gate portion 15 and on the side of the movable nest 9, and a pressure plunger 17 is slidable in the pressure sleeve 16. Is fitted. In the present example, a pressure mechanism is constituted by the pressure sleeve 16 and the pressure plunger 17. The pressurizing plunger 17 moves in the injection sleeve 11 in the axial direction (FIG. 1).
1 (horizontal direction), and the position of the solid line in FIG. 1 indicates the most retracted state in the mold clamping state. The right end side of FIG. 1 of the pressurizing plunger 17 is integrally connected to a pressurizing piston 18a slidably fitted in a pressurizing cylinder 18 forming a hydraulic drive mechanism.

In the pressurizing cylinder 18, the hydraulic pressure in the left and right two chambers divided by the pressurizing piston 18a is switched by a three-way switching solenoid valve 18b. The switching of the oil pressure controls the movement of the pressurizing plunger 17. On the other hand, a weir 19 for preventing the backflow of molten metal is formed in a portion of the runner portion 14 upstream of the pressurizing sleeve 16 and the pressurizing plunger 17. As shown in an enlarged view in FIG. 2, in this example, the weir 19 is formed in the runner portion 14 so as to protrude in a trapezoidal cross section from the surface of the movable nest 9. The cross-sectional area of the passage of the portion 14 is reduced. In FIG. 2, the illustration of the pressure sleeve 16 is omitted.

The specific design example of the weir 19 will be described in more detail. The length of the weir 19 in the flow direction of the molten metal (length of the upper side of the trapezoid) is 10 to 30 mm as shown in an experimental example described later. It is suitable, and more preferably, it is 15 to 25 mm.
In the design example of FIG. 2, the length of the weir 19 is set to 20 mm.
And, when the passage thickness of the runner part 14 is as shown in FIG.
mm, and with respect to the passage thickness of the runner portion 14,
The passage thickness at the weir 19 is preferably 1.5 to 3.5 mm. In the case of FIG. 2, the passage thickness at the weir 19 is 3 mm.
And The passage thickness of the weir 19 and the gate 1
The passage thickness at 5 is set to the same value. This is for the following reason.

That is, the adverse effect of the weir 19 on the flow of the molten metal is minimized, and the size of the molds 2 and 4 is minimized (when the thickness of the passage is doubled, the length of the weir 19 is quadrupled). It is preferable to make the passage thickness of the weir 19 portion and the passage thickness in the gate portion 15 the same. The height of the weir 19 and the gate 15 is 7 mm in the example of FIG. Further, slopes having inclination angles of 5 ° and 60 ° shown in FIG. 2 are formed on the upstream side and the downstream side of the weir 19 and the upstream side of the gate portion 15, respectively.

The portion of the weir 19 and the slope on the upstream side of the gate portion 15 are provided for smoothing the flow of the molten metal when the molten metal is filled by the injection mechanism. Similarly, a slope on the downstream side of the weir 19 is provided for facilitating the flow of the molten metal.
Next, the die casting method in the above-described die casting apparatus will be described. As shown in FIG. 1, in a state where the movable mold 4 is clamped with respect to the fixed mold 2, the injection plunger 12 is moved to the maximum retracted position 12b in FIG. To retreat. In this state, first, a molten metal (for example, aluminum alloy: equivalent to ADC14, temperature: 740 ° C.) is injected into the injection sleeve 11 from the injection port 13 by a molten metal injector (not shown).

Next, immediately after completion of the injection of the molten metal,
The injection plunger 12 is advanced toward the maximum advance position indicated by the solid line in FIG. As the injection plunger 12 advances, the molten metal in the injection sleeve 11 is spouted from the gate portion 15 through the runner portion 14 into the cavity 10 at a high speed.
The molten metal is press-fitted into the cavity 10. Here, the forward speed of the injection plunger 12 is, for example, low speed: 0.1 m / sec, and high speed: 1.9 m / sec.
c. The injection pressure (casting pressure) of the molten metal by the injection plunger 12 is, for example, 88.3 MPa.

Next, after filling the molten metal into the cavity 10, a predetermined time (for example, about 0.3 to 0.5 seconds,
After a lapse of a short time during which the molten metal does not solidify, the three-way switching solenoid valve 18b performs a switching operation of the hydraulic circuit to advance the pressurizing plunger 17 by a predetermined amount from the solid line position in FIG. Press the molten metal inside.
Due to this pressurizing action, a pusher effect can be exerted on the molten metal in the cavity 10 via the gate portion 15, thereby suppressing the occurrence of shrinkage cavities in the product portion in the cavity 10.

Here, the diameter of the pressure plunger 17 is, for example, 15 mm, and the forward stroke is, for example, 20 mm.
And the pressurizing pressure is 196 MPa. The pressurizing action of the pressurizing plunger 17 continues for a predetermined time until the solidification of the molten metal is completed, and then the pressurizing plunger 17 is retracted. Next, the direction in which the movable mold 4 is separated from the fixed mold 2 (FIG. 1)
(To the right) to open the mold, and the ejector pin (not shown) on the movable mold 4 side and the injection plunger 12 on the fixed mold 2 side are advanced to solidify in the space inside the cavity 10 and the runner section 14. Extrude die-cast products. Thereafter, the movable mold 4 is moved to the fixed mold 2 side to perform mold clamping, and the injection plunger 12 is moved in FIG.
Is retracted to the two-dot chain line position 12b. Thereby, all the steps of the series of die casting methods are completed.

By the way, as described above, the pressure plunger 1
When the molten metal in the runner portion 14 is pressurized by 7, a backflow preventing weir 19 is formed upstream of the pressurizing plunger 17, and the weir 19 narrows the passage cross-sectional area in the runner portion 14. The backflow of the molten metal pressurized by the pressurizing plunger 17 toward the injection sleeve 11 is prevented.
To effectively prevent the molten metal in the cavity 10 from being pushed.

On the other hand, when filling the molten metal into the cavity 10, there is a possibility that the operation of flowing the molten metal into the internal space of the cavity 10 (the effect of spreading the molten metal throughout the entire internal space of the cavity 10) may be reduced by the addition of the backflow preventing weir 19. is there. Therefore,
In order to effectively implement the present invention, it is important to achieve both the effect of preventing the backflow of the molten metal by the weir 19 and the effect of running the molten metal into the space inside the cavity 10. Therefore, the present inventors conducted the following experiment focusing on the specific specifications of the weir 19, particularly the length of the weir 19 in the flow direction of the molten metal, in order to achieve the above compatibility. That is, FIG. 3 shows the experimental results,
The abscissa indicates the length of the weir 19, and the ordinate indicates the product density in the vicinity of the gate portion 15 of the die-cast product and the defective run rate. The higher the product density,
Poor shrinkage nests decrease.

Here, the run-out defect rate is determined from the quality of the appearance of a die-cast molded product.
A judgment reference product is prepared in advance, and the quality is judged from a visual comparison between the appearance of the judgment reference product and the appearance of the die-cast product. Note that the product densities were each measured n = 5
Mean value, while the run-out defect rate indicates the number of measurements n = 10
The average value of 0 is shown.

As experimental conditions, dimensions other than the length of the weir 19 are as shown in FIG. 2, and other die casting conditions are as described in the above description of the method. As can be understood from the experimental results in FIG. 3, the longer the length of the weir 19 is, the more the backflow preventing effect of the molten metal is improved and the effect of pushing the molten metal in the cavity is improved, thereby increasing the product density. I understand. And the length of the weir 19 is 20
Up to 20 mm, the increase in product density is rapid, and when it is 20 mm or more, the increase in product density is almost saturated.

On the other hand, the run-out defect rate is as follows.
mm is maintained at 0%, and when the length of the weir 19 becomes 30 mm, the run-out defect rate becomes 1%, and the length of the weir 19 becomes 40%.
mm, the run-out defect rate rises to 5%. According to the experimental results of FIG. 3, the length of the weir 19 is preferably 10 to 30 mm, more preferably 15 to 25 mm.

In FIG. 3, the broken line indicates the product density when no pressure is applied by the pressure mechanism. Weir 1
When the length of 9 is 0, that is, when the weir 19 is not provided, even if the pressurization is performed, the effect of the pressurizing action by the pressurizing mechanism is offset by the backflow of the molten metal to the upstream side. Therefore, the product density has substantially the same value regardless of the presence or absence of the pressurizing action by the pressurizing mechanism.

FIG. 4 shows a second embodiment. In the first embodiment, a slope having an inclination angle of 5 ° is formed on both the upstream side and the downstream side of the weir 19, but in the second embodiment, The inclination angle of the slope on the upstream side of the weir 19 is enlarged to 60 °. Due to the increase in the inclination angle of the upstream slope, when the molten metal is press-fitted into the cavity 10 through the runner portion 14, the flow of the molten metal passing through the weir 19 can be made smooth, and the molten metal flowing into the cavity 10 can be smoothed. The circumference can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a die casting apparatus according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a graph showing experimental data of a product density and a run-out defect rate according to the present invention.

FIG. 4 is a partially enlarged sectional view of a die casting apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

2 ... fixed mold, 4 ... movable mold, 10 ... cavity, 11
... injection sleeve, 12 ... injection plunger, 14 ... runner part, 15 ... gate part, 16 ... pressurized sleeve, 17 ... pressurized plunger, 19 ... backflow prevention weir.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tomoyuki Hatano 1-1-1, Showa-cho, Kariya-shi, Aichi Pref.

Claims (5)

[Claims] 1. After a molten metal is pressed into a cavity (10) of a mold (2, 4) through a runner section (14) by an injection mechanism (11, 12), the molten metal is pressed by a pressing mechanism (16, 17). A die casting method for pressurizing the molten metal in the cavity (10) by pressing the molten metal in the runner section (14), wherein the pressurizing mechanism (16,
17) Weir (19) at the upstream side
When pressurizing the molten metal by the pressurizing mechanisms (16, 17), pressurizing the molten metal while preventing backflow of the molten metal to the upstream side by the weir (19). A die casting method. 2. A mold (2, 4) that can be opened and closed, a cavity (10) provided inside the mold (2, 4) and forming a product part, and the mold (2, 4). And a runner part (14) which is provided inside the cavity and serves as a passage of the molten metal when the molten metal is pressed into the cavity (10). The molten metal is pressed into the cavity (10) through the runner part (14). An injection mechanism (11, 12); and a pressurizing mechanism (16) provided in the runner section (14) for pressurizing the molten metal in the runner section (14) after the molten metal is pressed into the cavity (10). , 17)
And the pressurizing mechanism (1) in the runner section (14).
6, 17), the runner section (1)
4) a backflow preventing weir (19) provided so as to reduce the cross-sectional area of the passage; and when the pressurizing mechanism (16, 17) pressurizes the molten metal, the weir (19) A die casting apparatus, wherein pressurization of a molten metal is performed while preventing a backflow of the molten metal to an upstream side. 3. The die casting apparatus according to claim 2, wherein the length of the backflow prevention weir (19) in the flow direction of the molten metal is 10 to 30 mm. 4. The die casting apparatus according to claim 3, wherein the length of the backflow prevention weir in the direction of flow of the molten metal is 15 to 25 mm. 5. A gate section (15) provided at a downstream end of the runner section (14) and for discharging molten metal into the cavity (10) at a high speed by narrowing a passage cross-sectional area of the runner section (14). The passage thickness at the portion of the backflow prevention weir (19) and the passage thickness at the gate portion (15) are the same. Die casting equipment.