Die casting apparatus

Abstract

To suppress inflow of a molten metal before pressing by a pressing member.SOLUTION: In a die casting apparatus that performs die casting by depressurizing the inside of molds 2, 3, and pressing a molten metal filled in a sleeve 4 into a cavity 9 of the molds 2, 3 by a pressing member, a wall part 21 for suppressing inflow of a molten metal before being pressed by the pressing member is provided in a guide flow path 14 that guides the molten metal from the sleeve 4 to the cavity 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a die casting apparatus that performs die casting by forcing molten metal into a mold under reduced pressure. [Background technology]

[0002] 2. Description of the Related Art A known die-casting apparatus is a vacuum die-casting apparatus that reduces the pressure inside a die and forces molten metal into the cavity of the reduced-pressure die to perform die-cast molding.

[0003] Generally, a vacuum die-casting device comprises a movable mold, a fixed mold, a pressure reducing device that reduces the pressure inside the cavity formed by the movable mold and the fixed mold, and a pushing member that pushes the molten metal in a sleeve provided in the fixed mold into the cavity (see, for example, Patent Document 1: JP 2021-16860 A). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-16860 Summary of the Invention [Problem to be solved by the invention]

[0005] In molding methods using vacuum die-casting equipment, the pressure inside the cavity is first reduced before the molten metal is forced into it, which makes it easier for the molten metal to flow into the cavity. This has the advantage that the molten metal spreads throughout the entire cavity, preventing problems such as the formation of air bubbles in the molded product.

[0006] However, when the pressure inside the cavity is reduced, the negative pressure can cause part of the molten metal in the sleeve to flow into the cavity first. In this case, if the molten metal that flowed first solidifies and forms an initial solidified layer, and if the initial solidified layer is not remelted by the subsequent inflow of molten metal pushed into the cavity, there is a risk that the unremelted part will peel off from the molded product.

[0007] Therefore, an object of the present invention is to suppress the inflow of molten metal before it is pushed in by the push-in member. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a die-casting apparatus that reduces the pressure inside a mold and forces molten metal filled in a sleeve into the cavity of the mold using a pushing member to perform die-cast molding, characterized in that a guide flow path that guides the molten metal from the sleeve to the cavity is provided with a wall portion that suppresses the inflow of molten metal before it is pushed by the pushing member.

[0009] In this way, in the die-casting apparatus according to the present invention, because the wall portion is provided in the guide passage, even if the molten metal in the sleeve moves toward the cavity when the pressure inside the cavity is reduced, the migrated molten metal hits the wall portion and is blocked, thereby preventing the molten metal from flowing into the cavity. This makes it possible to solve problems such as peeling of the molded product caused by the inflow of molten metal before pushing. Furthermore, as a result of being able to prevent the inflow of molten metal before pushing, it is possible to further reduce the pressure inside the cavity, thereby more reliably filling the cavity with molten metal.

[0010] The wall portions are preferably provided so as to protrude from each of the opposing surfaces of the guide channel, in this case, the wall portions protruding from the opposing surfaces can more effectively suppress the inflow of the molten metal before it is pushed in.

[0011] The mold may have a movable mold and a fixed mold, and the wall may be provided on both the movable mold and the fixed mold. Of the movable mold and the fixed mold, the wall of the mold on which the sleeve is provided is preferably provided upstream of the wall of the other mold in the direction of molten metal flow. By providing the walls in such positions, it is possible to suppress the generation of turbulence caused by the molten metal hitting the wall, thereby maintaining a smooth flow of molten metal. [Effects of the Invention]

[0012] According to the present invention, the inflow of molten metal before pushing can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing the overall configuration of a die-casting apparatus according to an embodiment of the present invention; [Figure 2] 2 is an enlarged cross-sectional view showing a guide flow path of a die-casting device according to an embodiment of the present invention. FIG. [Figure 3] FIG. 2 is a plan view of the guide flow path according to the embodiment, as viewed from the fixed mold side. [Figure 4] FIG. 10 is a diagram for explaining the height of a wall portion. [Figure 5] FIG. 10 is a diagram showing an example in which wall portions are arranged at positions directly facing each other. [Figure 6] FIG. 10 is a diagram showing an example in which the wall of the movable mold is provided upstream of the wall of the fixed mold in the direction of molten metal flow. [Figure 7] FIG. 10 is a diagram showing an example in which the wall of the fixed mold is provided upstream of the wall of the movable mold in the molten metal inflow direction. [Figure 8] 7 is a diagram showing the flow of molten metal when the molten metal is extruded in the example of FIG. 6. FIG. [Figure 9] FIG. 8 is a diagram showing the flow of molten metal when the molten metal is extruded in the example of FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A die casting apparatus according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0015] <Die casting equipment configuration> FIG. 1 is a diagram showing the overall configuration of a die-casting apparatus according to one embodiment of the present invention.

[0016] As shown in FIG. 1, the die-casting apparatus 1 according to this embodiment includes a movable mold 2, a fixed mold 3, a sleeve 4, a pushing member 5, a pressure reducing device 6, and the like.

[0017] The movable mold 2 is attached to a movable platen 7, and the fixed mold 3 is attached to a fixed platen 8. When the movable platen 7 is driven to reciprocate in the horizontal direction (the lateral direction in FIG. 1) by a driving device such as a hydraulic cylinder, the movable mold 2 moves toward and away from the fixed mold 3. This causes the movable mold 2 and the fixed mold 3 to be clamped and opened. When the movable mold 2 and the fixed mold 3 are clamped together, a cavity 9 is formed between the movable mold 2 and the fixed mold 3.

[0018] The sleeve 4 is a cylindrical member provided between the fixed mold 3 and the fixed platen 8. The sleeve 4 is filled with a molten metal 10 such as aluminum through an opening 4a. A molten metal filling space 13 within the sleeve 4, into which the molten metal 10 is filled, communicates with the cavity 9 through a guide passage 14 formed between the movable mold 2 and the fixed mold 3. The guide passage 14 includes a runner 15 that communicates with the molten metal filling space 13, and a gate 16 that is provided between the runner 15 and the cavity 9.

[0019] The pushing member 5 has a plunger tip 11 inserted into the sleeve 4, and a plunger rod 12 having the plunger tip 11 attached to the tip thereof. The plunger rod 12 is connected to a driving device such as a hydraulic cylinder, and the driving device causes the plunger tip 11 to slide back and forth horizontally (the lateral direction in FIG. 1 ) within the sleeve 4.

[0020] The pressure reducing device 6 has a vacuum valve 17 provided in the fixed mold 3 and a vacuum pump 18 connected to the vacuum valve 17. The vacuum pump 18 is in communication with the cavity 9 via the vacuum valve 17. Therefore, when the vacuum pump 18 is driven with the vacuum valve 17 open, the air inside the cavity 9 is sucked out, and the pressure inside the cavity 9 is reduced.

[0021] <Die-cast molding method> Next, a molding method using the die-casting apparatus according to this embodiment will be described with reference to FIG.

[0022] First, as shown in FIG. 1 , the movable die 2 and the fixed die 3 are clamped together, and the sleeve 4 is filled with the molten metal 10. Next, the vacuum pump 18 is driven to suction the air from the cavity 9, thereby reducing the pressure inside the cavity 9. Then, while the pressure inside the cavity 9 is maintained at a reduced pressure, the pushing member 5 is driven to push the molten metal 10 into the cavity 9. More specifically, as the pushing member 5 moves leftward in FIG. 1 , the molten metal 10 inside the sleeve 4 is pushed out of the molten metal filling space 13, passes through the runner 15, and is pushed into the cavity 9 through the gate 16. At this time, the pushing force of the pushing member 5 and the negative pressure inside the cavity 9 act in combination on the molten metal 10, causing the molten metal 10 to flow smoothly into the cavity 9, thereby ensuring that the molten metal 10 is filled throughout the cavity 9. Thereafter, when the molten metal 10 in the cavity 9 has completely solidified, the movable die and the fixed die 3 are separated to open the die, and the molded product (cast product) is removed from the die.

[0023] <Issues with vacuum die-casting methods> However, in a vacuum die-casting apparatus in which the pressure inside the cavity is reduced before the molten metal is forced into the cavity, there is a problem in that a portion of the molten metal in the sleeve flows into the cavity first due to the negative pressure generated when the pressure inside the cavity is reduced. If a portion of the molten metal flows in first, the flowing molten metal solidifies and forms an initial solidified layer. If the initial solidified layer is not re-melted by the subsequent flow of molten metal forced into the cavity, the portion that did not re-melt may peel off from the molded product.

[0024] Therefore, the present invention proposes a die-casting machine that can suppress the inflow of molten metal before the die-casting is performed. Hereinafter, the features of the present invention will be described using the die-casting machine according to an embodiment of the present invention as an example.

[0025] <Characteristics of the present invention> FIG. 2 is an enlarged cross-sectional view showing the guide flow path 14 of the die-casting apparatus 1 according to one embodiment of the present invention.

[0026] 2, the guide flow path 14 according to this embodiment is provided with two wall portions 21 that protrude in directions facing each other. The two wall portions 21 are provided so as to protrude from the opposing surfaces 20, 30 of the movable mold 2 and the fixed mold 3 that form the guide flow path 14. Note that in FIG. 2, each wall portion 21 is formed with a triangular cross section, but the cross section of each wall portion 21 is not limited to a triangle and may be another cross section shape such as a trapezoid or a rectangle.

[0027] FIG. 3 is a plan view of the guide flow path 14 according to this embodiment, as viewed from the fixed mold 3 side.

[0028] 3, the wall 21 indicated by the solid line is the wall 21 on the movable mold 2 side, and the wall 21 indicated by the two-dot chain line is the wall 21 on the fixed mold 3 side. Arrow A in FIG. 3 indicates the molten metal inflow direction of the molten metal flowing toward the cavity 9. As shown in FIG. 3, each wall 21 is provided so as to extend in a direction intersecting or perpendicular to the molten metal inflow direction A.

[0029] As described above, in this embodiment, since the wall portion 21 as described above is provided in the guide flow path 14, it is possible to prevent a portion of the molten metal 10 from flowing into the cavity 9 before the molten metal 10 is pushed in by the push-in member 5. In other words, even if a portion of the molten metal 10 in the sleeve 4 moves from the molten metal filling space 13 to the runner 15 due to a reduction in pressure in the cavity 9 before the molten metal 10 is pushed in by the push-in member 5, the migrated molten metal 10 hits the wall portion 21 and is blocked, thereby preventing the molten metal 10 from flowing into the cavity 9.

[0030] This makes it possible to eliminate problems such as peeling of the molded product caused by the inflow of molten metal before pushing, thereby preventing the occurrence of defective products. In addition, as a result of being able to suppress the inflow of molten metal before pushing, it is possible to further reduce the pressure inside the cavity, which makes it possible to more reliably fill the cavity with molten metal and improve the quality of the molded product.

[0031] Here, the protrusion amount (height) of the wall portion 21 is not particularly limited and can be set appropriately. However, if the protrusion amount of the wall portion 21 becomes too large, the guide channel 14 becomes narrow at the position of the wall portion 21, and the portion where the molten metal 10 solidifies and is molded in the guide channel 14 (hereinafter referred to as the "runner portion") becomes locally thin, which may cause the runner portion to break when the molded product is removed from the mold. Although the runner portion is not fundamentally a part that becomes a product, if the runner portion breaks in the mold, the broken portion must be removed from the mold. Furthermore, if the runner portion breaks during a transportation process after being removed from the mold together with the molded product, the broken portion may fall into the manufacturing equipment and cause malfunctions. From this perspective, it is preferable that the protrusion amount of the wall portion 21 be set so as to eliminate the risk of the runner portion breaking.

[0032] Specifically, the protrusion amounts t1 and t2 of each wall portion 21 shown in Fig. 4 are preferably half or less of the width W of the guide channel 14 in the protruding direction of each wall portion 21 (t1, t2 ≤ W / 2). On the other hand, if the protrusion amounts of the wall portions 21 are too small, the inflow of the molten metal before being pushed in cannot be effectively suppressed. Therefore, the protrusion amounts t1 and t2 of each wall portion 21 are preferably at least one-third of the width W of the guide channel 14 and not more than one-half of that width W (W / 3 ≤ t1, t2 ≤ W / 2). Setting the protrusion amounts t1 and t2 of each wall portion 21 to values ​​within this range makes it possible to effectively suppress the inflow of the molten metal before being pushed in while preventing breakage of the runner portion.

[0033] 5, the two walls 21 may be provided so as to face each other at the same position in the molten metal inflow direction A, but in this case, the runner portion is likely to become locally thin where the walls 21 face each other. Therefore, in order to prevent breakage of the runner portion, it is preferable that the walls 21 be provided at positions offset from each other in the molten metal inflow direction A, as shown in FIG. 6, rather than facing each other directly.

[0034] Furthermore, the positions of the walls 21 may be opposite to those shown in Fig. 6, and may be those shown in Fig. 7. In Fig. 6, the wall 21 of the movable mold 2 is provided upstream of the wall 21 of the fixed mold 3 in the molten metal inflow direction A (at a position closer to the sleeve 4), but in Fig. 7, the wall 21 of the fixed mold 3 is provided upstream of the wall 21 of the movable mold 2 in the molten metal inflow direction A (at a position closer to the sleeve 4).

[0035] In particular, in a configuration like this embodiment in which the sleeve 4 is provided in the fixed mold 3 and the molten metal 10 in the sleeve 4 is extruded toward the movable mold 2, the position in Fig. 7 is more preferable than the position in Fig. 6. In the case of Fig. 6, when the molten metal is extruded from the sleeve 4, it is pressed forcefully against the movable mold 2 that faces the extrusion direction B, as shown in Fig. 8, and the molten metal also hits the wall portion 21 of the movable mold 2 with force, causing turbulence (see the dashed arrow in Fig. 8), which may hinder the smooth inflow of the molten metal.

[0036] 7, the wall 21 of the movable die 2 is farther from the sleeve 4 as shown in FIG. 9, which suppresses the generation of turbulence caused by the molten metal striking forcefully against the wall 21 of the movable die 2 (see the dashed arrow in FIG. 9). Thus, in the configuration of this embodiment, the position in FIG. 7 is more preferable than the position in FIG. 6 in terms of maintaining smooth inflow of the molten metal.

[0037] The above describes an embodiment of the die casting apparatus of the present invention, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0038] In the above-described embodiment, a configuration in which the molten metal is extruded horizontally from the sleeve 4 toward the movable mold 2 has been described as an example, but the present invention is not limited to a configuration in which the molten metal is extruded horizontally, and can also be applied to a configuration in which the molten metal is extruded in other directions.

[0039] Furthermore, the wall portion 21 may be provided on both the movable mold 2 and the fixed mold 3, or may be provided on only one of the molds. For example, if the groove of one of the molds that forms the guide flow path 14 has a U-shaped cross section, the wall portion 21 may be provided so as to protrude from each of the opposing side surfaces of the groove.

[0040] The number of wall portions 21 may be 2 or may be 3 or more. The number of wall portions 21 may be 1, but from the viewpoint of more reliably suppressing the inflow of molten metal, it is preferable that the number of wall portions 21 is plural. [Explanation of symbols]

[0041] 1. Die-casting equipment 2 Movable type 3 Fixed type 4 sleeves 5 Push-in member 6. Pressure reducing device 9 Cavity 10 Molten metal 14 Guide channel 21 Wall

Claims

1. A die casting apparatus for performing die casting by reducing the pressure inside a die and forcing molten metal filled in a sleeve into a cavity of the die using a pushing member, A die casting apparatus characterized in that a guide passage that guides the molten metal from the sleeve to the cavity is provided with a wall portion that suppresses the inflow of the molten metal before it is pushed in by the pusher member.

2. The die casting machine according to claim 1 , wherein the wall portions are provided so as to protrude from opposing surfaces of the guide flow passage.

3. The mold has a movable mold and a fixed mold, the wall portion is provided on both the movable mold and the fixed mold, 3. The die casting apparatus according to claim 1, wherein the wall portion of one of the movable and fixed dies, in which the sleeve is provided, is located upstream of the wall portion of the other die in the molten metal flow direction.

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