JP2001071109A - Die for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a product having large projection area by forming the cross sectional shape as a round shape and providing a runner whose cross sectional area is gradually reduced on the way to a sprue. SOLUTION: The cross sectional area of the round runner part 2 is set so as to be gradually reduced as approaching to the sprue part 5. Further, the runner part near the sprue part 5 is formed as a fan-shape runner part 4 so that the arc part of the fan becomes the sprue part 5, and this cross sectional area is gradually reduced as coming to the sprue part 5. When the large and thin casting product 1 is formed by using this die, since the projection area of the runner part 2 is reduced in the way from a feeder head 3 to the sprue part 5, the molten metal power which tends to open the die at the forming time, is reduced. Further, since the cross section of the runner part 2 is round, the area where the molten metal is brought into contact with the die, becomes the minimum, and as a result, since the heat loss of the molten metal is reduced and the solidification of the molten metal can be delayed, the filling of the molten metal in the die is smoothly executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a runner and a gate of a die casting mold for forming a large thin cast product.

[0002]

2. Description of the Related Art Die casting is known as a method for mass-producing thin and precise cast products. In this casting method, the filling of the molten metal into the mold in a short time before solidification proceeds, that is, high-speed and high-pressure filling of the molten metal is required.

According to the runner design method in the die casting method, the filling time is determined by the requirement that the molten metal be completely filled in the mold in a short time before the solidification of the molten metal proceeds. Also, it is necessary to make the molten metal flow into the product section faster,
In order to avoid breakage of the gate, it is necessary to limit the flow velocity of the gate to a certain speed or less.

Here, it is known that the required cross-sectional area of the gate section is obtained by dividing the volume to be filled (hereinafter referred to as the filling volume) by the filling time and the flow rate of the gate section as shown in the equation in FIG. ing. From the above, it can be said that the filling time and the flow velocity at the gate section are values determined by the properties of the molten metal and the like, and therefore, if it is considered to be constant, as a result, the necessary cross-sectional area is proportional to the filling volume.

FIG. 4 shows a state in which a runner and a large and thin cast product are laid out on a mold by a conventional runner design method. When a large casting is produced, the required filling area of the gate section 5 increases because the filling volume increases. FIG. 5A is a cross-sectional view of the runner in a direction perpendicular to the flow of the molten metal (CC cross section in FIG. 4), and FIG. 5B is a partially enlarged view thereof.

Since the casting is a thin casting, the gate thickness t is narrowed down from the product plate thickness T and set to be smaller than the product plate thickness T as shown in FIG. Therefore, even if the casting volume is the same, the width a of the gate section 5 is smaller than when the casting product is not thin.
Is set to be large, and as a result, the width of the runner 2 communicating with the gate section 5 is also increased, and as a result, the projected area is increased.

FIG. 6 is a sectional view (DD section in FIG. 4) of the runner section 2 in the direction of flow of the molten metal. The cross section of the runner 2 is a shape suitable for processing a mold, and no consideration is given to adjusting the flow velocity of the molten metal.

[0008]

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 runner and the product section are combined. Because the projected area is large, there is a certain limitation on the projected area of the product even if molding is performed with a die-casting molding machine with the highest class clamping ability that exists in the current state of the art. However, there has been a demand for improvement so that it can be formed by die casting.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been developed to effectively solve the above-mentioned conventional problems. In a die casting mold having a runner from a feeder section to a gate section, a cross-sectional shape is provided. Is a circular shape, and has a runner whose cross-sectional area is gradually reduced in the process of reaching the gate.

In a die-casting mold having a runner from a feeder section to a gate section, the runner is expanded near the gate section,
The above problem can also be solved by a die-casting die characterized in that the sprue is formed in a fan shape having an arc shape and the cross-sectional area of the fan shape is gradually reduced from the runner to the sprue.

Furthermore, in a die-casting mold having a runner from a feeder section to a gate section, a cross-sectional shape is circular,
The cross section has a runner that gradually decreases in the process of reaching the gate, and the runner is widened in the vicinity of the gate, and the gate is formed into a fan shape having an arc shape. The above problem can also be solved by a die casting mold characterized in that the size is gradually reduced toward the part.

A die casting mold for forming an automobile body part having a runner extending from a feeder section to a plurality of gate sections, and having a thin plate at one portion and a thick plate at the other portion. The above problem can also be solved by a die-casting die characterized in that the gap between the gate portions connected to the portion is roughly set and the interval between the gate portions connected to the other portion is made close.

The operation of the present invention will be described below. According to the die casting mold of the present invention, the molten metal flows from the riser to the gate through the runner. If the cross section of the runner is made circular in this process, the projected area becomes smaller than that of the runner according to the conventional runner design method. As the projected area decreases, the force of the molten metal to open the mold during molding decreases.Therefore, compared to the case where the runner and the cast product are laid out on the mold by the conventional runner design method, The required mold clamping force can be reduced.

Further, as the cross-sectional area of the runner gradually decreases, the flow speed of the molten metal increases, and the flow speed does not decrease even near the gate, preventing the entrainment of air in the runner. It is possible to prevent the occurrence of a gas trap which causes a nest to be generated.

When a large thin cast product is formed using a die casting mold, the thickness of the gate is set to be smaller than the product plate thickness as described in the section of the prior art. If the cross section of the runner is circular, and if the cross section of the gate is the same as the conventional runner, the radius is smaller than the product wall thickness of the cast product, and the cross section of the gate is extremely large. Becomes smaller. Therefore, as can be seen from the relational expression such as the filling area and the gate section cross-sectional area shown in FIG. 7, the flow rate of the molten metal becomes extremely high, and the gate section may be damaged. Therefore, the gate section is formed into a fan shape with the product side as the arc side, and the cross-sectional area from the runner to the gate is gradually reduced in this fan shape, so that the desired speed can be obtained without excessively decreasing the flow rate of the molten metal. Can be obtained.

[0016] Further, by using the mold having the runner according to claim 1 and the spout according to claim 2, the flow rate of the molten metal from the feeder in the runner and in the spout does not fall into the cavity. Since the molten metal is used, generation of a gas trap or the like can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the die casting mold according to the present invention will be described in detail with reference to the accompanying drawings.
The product shown in FIG. 1 is a large thin cast product 1 in which a side pillar 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 is thicker below the line h corresponding to the waist line of the car body, and has a strength that can secure safety at the time of a side collision. The structure takes into account weight reduction. FIG. 2A is a cross-sectional view taken along the line AA in FIG. 1, showing each cross-sectional shape in the flow direction of the molten metal in the runner section 2, and FIG. 2B is an enlarged view of that portion. FIG. 3 shows FIG.
3 is a cross-sectional view taken along line BB of FIG.

The sectional area of the circular runner section 2 is set so as to gradually decrease as it approaches the product shape section (gate section 5), as shown in FIG. 2 (a).

As shown in FIG. 1, the runner in the vicinity of the sprue 5 is a fan-shaped runner 4 in which the arc of the fan becomes the sprue 5. At this time, the cross-sectional area of the fan-shaped runner 4 gradually decreases as it reaches the gate 5.

Further, the interval between the gates 5 is set so that the upper portion of the product having a small thickness is coarse and the lower portion of the product having a larger thickness than the upper portion is dense.

Since the required cross-sectional area of the gate section 5 is proportional to the filling volume according to the relation shown in FIG. 7, if the gate thickness t is the same in FIGS. 1 and 4, the gate width is the same. It is. That is, in relation to the gate width by the conventional method of designing a runner, the sum of the widths a to h of the gate 5 in FIG. 1 is equal to the sum of the widths a ′ to g ′ of the gate 5 in FIG. The relationship of coincidence is established.

When a large thin cast product 1 is formed using the die casting mold, the runner 2 through which the molten metal flows becomes a feeder 3
Since the projected area is reduced in the process from the gate to the sprue 5, the projected area is smaller than in the conventional runner, and as a result, the force of the molten metal for opening the mold during molding is reduced.

Further, by making the cross section of the runner circular, the area where the molten metal contacts the mold is minimized. That is, the heat loss of the molten metal is reduced, and the progress of the solidification of the molten metal can be delayed. Therefore, the filling of the molten metal in the mold is performed smoothly, and the force of the molten metal for opening the mold is reduced similarly to the above.

Further, since the cross-sectional area from the runner section 2 to the gate section 5 is gradually reduced, the flow velocity of the molten metal is increased, and the molten metal is melted in the mold near the gate section 5 without decreasing the flow velocity. Therefore, generation of a gas trap can be prevented.

In particular, by gradually reducing the cross-sectional area from the fan-shaped runner section 4 to the gate section 5, the flow rate of the molten metal can be adjusted, and even when the large thin cast product 1 is formed, the gate is used. The breakage of the part 5 can be avoided.

Here, when the degree of reduction of the cross-sectional area in the fan-shaped runner section 4 is small, due to the straight inertia of the molten metal from the circular runner section 2, the circular arc section of the fan-shaped runner section 4 (cast product) Side) Since the molten metal is not filled at both ends and there is a possibility that a problem such as poor running of the molten metal may occur, it is necessary to pay attention to the flow velocity of the molten metal when setting the degree of reduction of the sectional area in the fan-shaped runner section 4. is there.

[0027]

According to the present invention, since the projected area of the gate section is minimized, the projected area of the product section can be relatively increased. Therefore, the casting product is laid out on the mold by the conventional runner design method. As compared with the case, a larger product can be obtained by using a molding machine having a similar clamping force.

Further, since the surface area ratio to the volume of the runner is minimized, the amount of heat loss of the molten metal is reduced, so that the molten metal can be filled with increased heat retention efficiency in the runner. In addition, since the cross-sectional area of the runner portion is gradually reduced, the flow of the molten metal is gradually increased, and a decrease in the flow velocity in the passage of the runner is prevented, thereby preventing a gas trap.

In particular, when molding a large thin cast product, the flow rate of the molten metal can be adjusted, and breakage of the gate can be avoided.

Further, there is provided a die casting mold for forming an automobile body part having a runner extending from a feeder section to a plurality of gate sections, wherein one part has a small plate thickness and the other part has a large plate thickness. Because the gap between the gates connected to one part is coarse and the gap between the gates connected to the other part is made dense, for example, the center pillar outer has side sill outer,
Even when forming a large thin cast product in which the upper plate is thinner and the lower plate is thicker in which the side rails and the outer are integrated, the filling timing of the molten metal at the product terminal can be made simultaneously. That is, since the filling timing of the molten metal is simultaneous, the filling of the molten metal in one product terminal is completed, and the filling of the molten metal in another product terminal is not completed. Since no force for inflow of the molten metal is generated and this force does not become a force for opening the mold, the mold clamping force can be reduced.

[Brief description of the drawings]

FIG. 1 is a mold layout diagram of a runner of a die casting mold 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 section in the flow direction of the molten metal in FIG.

FIG. 3 is a cross-sectional view of the runner in a direction perpendicular to the flow of the molten metal in FIG. 1 (cross-section taken along line BB in FIG. 1).

FIG. 4 is a mold layout diagram of a runner and a large thin cast product according to a conventional runner design method.

5 is a cross-sectional view of the runner in a direction perpendicular to the flow of the molten metal in FIG. 4 (a cross section taken along line CC in FIG. 4).

6 is a sectional view (DD section in FIG. 4) of the runner and the gate section in the flow direction of the molten metal in FIG. 4;

FIG. 7 is a formula showing a relationship between a required cross-sectional area of a gate section, a filling volume, a filling time, and a filling volume.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large thin cast product 2 Runner 3 Feeder 4 Fan-shaped runner 5 Gate 6 Moving mold 7 Fixed mold ag g Width of runner t Thickness of gate T Product thickness

Claims (4)

[Claims] 1. A die casting mold having a runner from a riser to a sprue, characterized in that the cross-sectional shape is circular and the cross-sectional area is gradually reduced in the process of reaching the sprue. Die casting mold. 2. A die-casting mold having a runner from a feeder section to a gate section, wherein the runner is widened in the vicinity of the gate section, and the gate section is formed into a fan shape having an arc shape. Die-casting dies, characterized in that they are gradually reduced from the opening to the gate. 3. A die-casting die having a runner from a riser to a sprue, wherein the cross-sectional shape is circular, and the cross-section has a runner that gradually decreases in the process of reaching the sprue; A die-casting die characterized in that the runner is widened in the vicinity of the sprue and is shaped like a fan with a circular arc in the sprue, and the cross-sectional area of the fan gradually decreases from the runner to the sprue. 4. A die casting mold having a runner extending from a feeder section to a plurality of gate sections, wherein one part has a small thickness and another part has a large thickness. A die casting mold characterized in that the gap between the gate portions connected to one part is made coarse and the gap between the gate parts connected to the other part is made dense.