JP3603687B2 - Die casting mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a runner and a sprue of a die casting mold for forming a large thin cast product.
[0002]
[Prior art]
A die casting method is known as a method for mass production of thin and precise casting products. This casting method is required to complete the filling of the molten metal in a short time before solidification proceeds, that is, to fill the molten metal at a high speed and a high pressure.
[0003]
According to the runner design method in the die-casting method, the filling time is determined from the requirement that the molten metal be filled in a short time before the molten metal solidifies. Moreover, although it is necessary to make a molten metal flow into a product part faster, in order to avoid damage to a gate part, it is necessary to restrict | limit the flow rate of a gate part below to a fixed speed.
[0004]
Here, it is known that the required cross-sectional area of the gate is obtained by dividing the volume to be filled (hereinafter referred to as filling volume) by the filling time and the flow rate of the gate as shown in FIG. From the above, it can be said that the filling time and the flow velocity at the gate are determined by the properties of the molten metal and so on, and are considered to be constant, as a result, the required cross-sectional area is proportional to the filling volume.
[0005]
FIG. 4 shows a state where a runner and a large and thin cast product are laid out on a mold by a conventional runner design method. In the case of producing a large casting, the filling volume increases, so that the required cross-sectional area of the gate portion 5 increases. Fig.5 (a) is sectional drawing (CC cross section in FIG. 4) in the runner in the direction perpendicular | vertical to the flow of a molten metal, Furthermore, FIG.5 (b) shows the elements on larger scale.
[0006]
Since it is a thin-walled casting, the sprue thickness t is squeezed from the product plate thickness T and set smaller than the product plate thickness T as shown in FIG. Therefore, even if it is a casting product with the same filling volume, the width ah of the gate part 5 will be set large compared with the case where it is not thin, As a result, the width of the runner part 2 connected to the gate part 5 is also large. As a result, the projected area increases.
[0007]
Moreover, FIG. 6 shows sectional drawing (DD cross section in FIG. 4) of the molten metal flow direction of the runner part 2. As shown in FIG. The cross-sectional shape of the runner portion 2 is a shape suitable for processing a mold, and no consideration is given to the flow rate adjustment of the molten metal.
[0008]
[Problems to be solved by the invention]
When a large thin cast product is formed using a mold having a runner and a sprue designed by the above-described conventional runner design method, the projected area of the runner and the product portion is increased, so the current Even if molding is performed on a die casting machine that has the highest mold clamping capability existing in the technical level, there is a certain limitation on the projected area of the product so that products with a larger projected area can be molded by the die casting method. Improvement was requested.
[0010]
[Means for Solving the Problems]
The present invention, in order to achieve the above object, a die-casting die having a runner reaching the sprue from the riser portion, widening the runner near the sprue, and fan-shaped to arc the sprue, the fan The present invention provides a die casting mold characterized in that the cross-sectional area is gradually reduced from the runway toward the gate .
[0013]
Hereinafter, the operation of the present invention will be described.
According to the die casting mold of the present invention, the molten metal reaches from the feeder part to the gate through the runner part. If the cross-sectional shape of the runner is circular in this process, the projected area is smaller than that of the runner by the conventional runner design method. As the projected area decreases, the power of the molten metal that attempts to open the mold during molding decreases, so the runner and cast product are laid out on the mold using the traditional runner design method. The required clamping force can be reduced.
[0014]
In addition, since the cross-sectional area of the runner is gradually reduced, the flow velocity of the molten metal increases, the flow velocity does not decrease even near the gate, and air entrapment in the runner is prevented, resulting in the nest generated in the cast product. It is possible to prevent the occurrence of a gas trap that causes the above.
[0015]
When forming a large thin cast product using a die casting mold, the thickness of the gate is set smaller than the product plate thickness as described in the section of the prior art. When the cross-sectional shape of the runner is circular, if the cross-sectional shape of the sprue part is circular as in the conventional case, the radius will be smaller than the product thickness of the cast product, and the cross-sectional area of the sprue part will be extremely low. Becomes smaller. Therefore, as can be seen from the relational expression such as the filling area and the gate cross-sectional area shown in FIG. 7, the flow rate of the molten metal becomes extremely fast, and there is a possibility that the gate will be damaged. Therefore, the sprue portion is shaped like a fan with the product side as an arc, and the cross-sectional area from the runner to the sprue is gradually reduced within this fan shape, so that the desired speed can be achieved without excessively reducing the flow rate of the melt. Can be obtained.
[0016]
In addition, by forming a mold having the runner according to claim 1 and the sprue according to claim 2, the molten metal is melted into the cavity without dropping the flow velocity of the melt from the feeder into the runner and the spout. Therefore, the occurrence of gas traps and the like can be prevented.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a die casting mold according to the present invention will be described below in detail with reference to the accompanying drawings.
The product shown in FIG. 1 is a large-sized thin cast product 1 in which a side sill outer 1b and a side rail outer 1c are integrated with a center pillar outer 1a which is an automobile body part. Here, this product has a thickness that is thicker than the line h corresponding to the waistline of the automobile body, and has a strength that can ensure safety at the time of a side collision, and the thickness above the line h is also thin, It has a structure that considers weight reduction. 2A is a cross-sectional view taken along the line AA in FIG. 1 and shows cross-sectional shapes of the runner portion 2 in the flow direction of the molten metal, and FIG. 2B is an enlarged view of that portion. FIG. 3 is a cross-sectional view taken along the line BB in FIG.
[0018]
The cross-sectional area of the circular runner portion 2 is set so as to gradually decrease as the product shape portion (pouring gate portion 5) approaches, as shown in FIG.
[0019]
In addition, as shown in FIG. 1, the runner near the gate 5 is a fan-shaped runner 4 in which the arc portion of the fan becomes the gate 5. At this time, the cross-sectional area of the fan-shaped runner portion 4 is gradually reduced as it reaches the gate portion 5.
[0020]
Further, the interval between the gate portions 5 is set so that the upper part of the product having a small plate thickness is coarse and the lower part of the product having a thicker plate thickness than the upper part of the product is dense.
[0021]
Since the necessary cross-sectional area of the gate 5 is proportional to the filling volume from the relational expression shown in FIG. 7, if the gate thickness t is the same in FIGS. 1 and 4, the gate width is the same. That is, in the relationship with the gate width by the conventional design method of the gate, the sum of the widths a to h of the gate portion 5 in FIG. 1 is the sum of the widths a ′ to g ′ of the gate portion 5 in FIG. The relationship of matching is established.
[0022]
When the large thin cast product 1 is formed using this die casting mold, the projected area of the runner 2 where the molten metal flows from the feeder 3 to the gate 5 is reduced, so that Compared with the road portion, the projected area is reduced, and as a result, the force of the molten metal to open the mold during molding is reduced.
[0023]
Further, by making the cross-sectional shape of the runner circular, the area where the molten metal contacts the mold is minimized. That is, the amount of heat loss of the molten metal is reduced, and the progress of solidification of the molten metal can be delayed. Therefore, the molten metal is smoothly filled in the mold, and the force of the molten metal for opening the mold is reduced as described above.
[0024]
Furthermore, since the cross-sectional area from the runner 2 to the spout 5 is gradually reduced, the flow velocity of the molten metal increases, and the molten metal is melted in the mold without decreasing the flow velocity near the spout 5. Generation of straps can be prevented.
[0025]
In particular, by sequentially reducing the cross-sectional area from the fan-shaped runner 4 to the gate 5, the flow rate of the molten metal can be adjusted, and even when forming the large thin cast product 1, Damage can be avoided.
[0026]
Here, when the degree of reduction of the cross-sectional area in the fan-shaped runner portion 4 is small, both ends of the arc portion (casting product side) of the fan-shaped runner portion 4 due to the straight-run inertia of the molten metal from the circular runner portion 2 Therefore, it is necessary to pay attention to the flow rate of the molten metal when setting the degree of reduction of the cross-sectional area in the fan-shaped runner section 4.
[0027]
【The invention's effect】
According to the present invention, since the projected area of the gate is minimized, the projected area of the product can be relatively increased. Therefore, compared with the case where the cast product is laid out on the mold by the conventional runner design method, Larger products can be obtained using a molding machine with a degree of clamping force.
[0028]
In addition, since the surface area ratio with respect to the runner volume is minimized, the amount of heat loss of the molten metal is reduced, so that it is possible to increase the temperature of the molten metal at the runner and fill it. In addition, since the cross-sectional area of the runner portion is sequentially reduced, the flow of the molten metal is sequentially accelerated, preventing a decrease in flow velocity during the runner passage process and preventing gas trapping.
[0029]
In particular, in the case of molding a large thin cast product, the flow rate of the molten metal can be adjusted, and breakage of the gate can be avoided.
[0030]
And a die casting mold for molding an automobile body part having a runner from a feeder to a plurality of gates, wherein one part is thin and the other part is thick. For example, the center pillar outer is integrated with a side sill outer and a side rail outer so that the gap between the gates connected to the part is rough and the gap between the gates connected to the other part is increased. Even when forming a large thin cast product with a thin plate thickness and a thick lower plate thickness, it is possible to simultaneously fill the molten metal at the product terminal. That is, since the filling timing of the molten metal is the same, the filling of the molten metal at one product terminal is completed and the filling of the molten metal is not completed at the other product terminal. Since the force for the molten metal to flow in does not occur and this force does not become the force for opening the mold, the clamping force can be reduced.
[Brief description of the drawings]
FIG. 1 is a layout diagram of a die casting mold runner and a large thin cast product according to the present invention.
FIG. 2 is a cross-sectional view (cross section AA in FIG. 1) of a runner and a gate in the molten metal flow direction of FIG. 1;
3 is a cross-sectional view of the runner in a direction perpendicular to the molten metal flow in FIG. 1 (cross section BB in FIG. 1).
FIG. 4 is a mold layout diagram of a runner and a large thin cast product by a conventional runner design method.
5 is a cross-sectional view of the runner in a direction perpendicular to the molten metal flow in FIG. 4 (CC cross section in FIG. 4).
6 is a cross-sectional view (DD cross section in FIG. 4) of the runner and the gate in the molten metal flow direction of FIG. 4;
FIG. 7 is an equation showing the relationship between the required cross-sectional area of the gate and the filling volume, filling time, and filling volume.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Large-sized thin cast product 2 Runway part 3 Feeding part 4 Fan-like runway part 5 Spout part 6 Moving mold 7 Fixed mold ag The width of the runner part t Thickness of the spout part T Product thickness

Claims (3)

In die-casting molds that have a runway from the feeder to the gate,
Die-casting die characterized by spreading the runner near the gate and making it into a fan shape with an arc at the gate, and the fan- shaped cross-sectional area is gradually reduced from the runway to the gate. In die-casting molds that have a runway from the feeder to the gate,
The cross-sectional shape is circular, and the cross-sectional area has a runner that gradually decreases in the process of reaching the gate,
The die casting mold is characterized in that the sluice is spread out in the vicinity of the sluice part and is formed into a fan shape with a sluice part as an arc, and the fan-shaped cross-sectional area is gradually reduced from the sluice to the spout part. A die-casting die that has a runner from a feeder part to a plurality of gates, and a molded part having a thin plate thickness at one site and a thick plate at the other site,
The die casting mold according to any one of claims 1 and 2, wherein the gap between the gates connected to one part is rough, and the distance between the gates connected to the other part is close.

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