JPH0710841Y2 - Die casting equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a die casting mold applied to a die casting apparatus of a type in which a secondary pressurizing pressure is applied to a molten metal filled in a mold cavity. .

Prior art and its problems In the pressure die casting method in which molten metal is cast at high pressure (referred to simply as die casting method), a porosity occurs in the thick portion and the crystal structure becomes coarse, resulting in a decrease in the strength of the thick portion. There was a tendency. In order to solve this problem, a method has been proposed in which the molten metal is pressurized and filled in the cavity of the mold, and a secondary pressure is applied to the molten metal in the cavity before the molten metal solidifies (eg, Japanese Patent Publication No. 48-7570, Japanese Patent Publication No. 49
-36093 publication).

The main structure of the mold used in this method is, for example, as shown in FIG. Reference numeral 01 denotes a mold, and a pressure rod 03, which is driven to move back and forth by a secondary pressure cylinder device, is slidably fitted in an opening 02 formed through the mold 01.

The pressurizing rod 03 is pushed forward into the molten metal filled in the cavity A and applies a secondary pressurizing pressure to the molten metal before solidification.

However, the molten metal filling pressure and the secondary pressurizing pressure in the cavity A are very large, and the molten metal enters the small gap between the peripheral wall of the opening 02 and the pressurizing rod 03 and solidifies to form flash. When pulling the cast product away from the mold 01 after the completion of casting, not only a large force is required, but also the end peripheral wall of the opening 02 and the pressure rod 03
There is a problem that the tip of the is scratched.

Further, even if the mold 01 is used repeatedly, forced cooling is performed by spray coating a mold release agent on the inner surface of the cavity and the temperature is kept relatively low, The pressurizing rod 03 that has entered is expanded by being heated to a high temperature, and when the pressurizing rod 03 retracts into the opening 02 with a small expansion amount due to thermal expansion, the end peripheral wall of the opening 02 and the pressing rod 03 are “Gnailing” between
Not only is there a possibility that the pressure rod 03 will get stuck and get stuck.

Means for Solving the Problems The present invention relates to an improvement of a die casting apparatus that overcomes such problems, and fills the mold cavity with the molten metal, and before the molten metal solidifies, the wall surface and the surface of the mold. A die-casting device of a type for advancing a pressure rod that has retreated to the inside into a cavity to apply a secondary pressure to the molten metal, which is an opening for a pressure rod formed through a wall of a mold. Is formed as a truncated cone surface with a hole diameter increasing toward the cavity side facing the inside of the cavity, and chamfering is performed around the tip of the pressure rod, and the chamfer corresponds to the truncated cone surface of the hole end. Formed as a truncated conical surface of the reverse slope, and the conical surface around the opening end,
The frusto-conical surface around the tip of the pressure rod is characterized in that their heights in the advancing / retreating direction of the pressure rod are equal.

Embodiment An embodiment of the present invention shown in FIGS. 2 to 4 will be described below.

FIG. 2 shows the die casting apparatus 10 capable of exerting the secondary pressurization pressure together with the secondary pressurization hydraulic control system 64. On the base 12 of the die-casting device 10, fixed platens 14 and 16 that are mutually connected by a plurality of connecting rods 18 and are opposed to each other with a space therebetween are fixedly erected. Also, it is located between the fixed platens 14 and 16, and the connecting rod 1
A movable platen 20 guided by 8 and slidingly displaced on the base 12 is provided.

The fixed mold 22 is fixed to the fixed platen 16, and the movable mold 24 is fixed to the movable platen 20 via the holder 30. The extrusion pin 36 that penetrates the movable mold 24 and faces the cavity A, and is used to separate the product after the completion of casting from the movable mold 24, is a holding rod that penetrates the movable mold 24 so as to be slidable and relatively displaceable. It is fixed to an extruding plate 32 supported by 34, and the extruding plate 32 is moved in the product separating direction relative to the movable mold 24 by a push rod 40 connected to a piston of an extruding hydraulic cylinder 38. It is like this.

Further, the movable platen driving hydraulic cylinder 42 is fixed to the fixed platen 14, and the movable platen 20 is moved by a push rod 44 integrated with the piston thereof.

Further, the injection hydraulic cylinder 46 is fixed to the fixed platen 16 with the support rod 52, and the injection ram 50 connected to the piston 48 of the injection hydraulic cylinder 46 penetrates the fixed platen 16 to the injection sleeve 54 which communicates with the runner of the fixed mold 22. It is fitted so that it can slide and displace, and after the molten metal is supplied into the injection sleeve 54 through the pouring port 56, when the injection ram 50 moves in the forward direction by the operation of the piston 48, the molten metal in the injection sleeve 54 runs. It is designed to be pushed into the cavity A through.

On the other hand, in the movable mold 24, a secondary pressurizing hydraulic cylinder 60 is supported via a holding rod 58, and a pressurizing rod 62 connected to a piston of the hydraulic cylinder 60 has a pushing plate 32 and a movable mold.
It is configured so that it can penetrate into the cavity A by slidably displacing it. The periphery of the tip of the pressure rod 62 is chamfered to form a truncated cone surface 63, and this shape contributes to improving the structure of the cast product.

The hydraulic control system 64 of the secondary pressurizing hydraulic cylinder 60 takes out the working pressure of the injection hydraulic cylinder 46 through the oil passage 68, and operates using this as a pointer. Ie hydraulic cylinder 46
When the working pressure of the sequence valve 70 is guided to the sequence valve 70, the sequence valve 70 capable of adjusting the starting pressure by using the biasing spring force operates and the pressure oil discharged from the hydraulic pump 66 is transferred to the oil passage. 72, a switching valve 74, a flow rate adjusting valve 76, and a pressure rod advancing oil passage 78 are guided to the secondary pressure hydraulic cylinder 60, and the pressure rod 62 operates so as to enter the cavity A. System 64 is constructed.

FIG. 3 shows an enlarged view of the cavity A portion defined by the fixed mold 22 and the movable mold 24. The characteristic configuration of the present embodiment is that the periphery of the end of the pressure rod opening 26 formed through the movable mold 24 is formed as a truncated cone peripheral wall 28 whose hole diameter increases toward the cavity side. It is a part. The inclination angle (θ ₀ ) of the frustoconical peripheral wall 28 is preferably 45 degrees, and the height (h ₀ ) of the frustoconical peripheral wall 28 in the advancing / retreating direction of the pressing rod is equal to that of the pressing rod 62. when the outer diameter of the the 10 mm ^phi, it is desirable to do this in the 2-4 mm (Figure 4).

Further, with the tip end surface of the pressure rod 62 flush with the inner wall surface of the movable mold 24, the truncated cone surface 63 and the truncated cone peripheral wall 28 face each other to form a V-shaped cross section. The height (h ₁ ) of the truncated cone surface 63 in the forward / backward direction is equal to the height (h ₀ ) of the truncated cone peripheral wall 28.

In such a configuration, the injection sleeve 54 through the pouring port 56
When the injection ram 50 is moved forward by the operation of the injection hydraulic cylinder 46 after the molten metal (eg, aluminum alloy) is injected into the cavity A, the molten metal in the injection sleeve 54 is pressurized and filled in the cavity A. Further, when the hydraulic pressure in the high-pressure chamber is guided to the sequence valve 70 through the oil passage 68 at the same time as the operation of the injection hydraulic cylinder 46 is started, the hydraulic pressure reaches a certain level (T ₀ ) (that is, in the cavity A). (When the molten metal has been filled in)
Is displaced from the state shown in FIG. 2, the sequence valve 70, oil passage 72, switching valve 74, flow rate adjusting valve 76, pressurizing rod advancing oil passage
The discharge oil of the hydraulic pump 66 is sent to the high pressure chamber of the secondary pressurizing hydraulic cylinder 60 through 78, and the pressurizing rod 62 moves forward and is pushed into the molten metal that fills the cavity A, and the solidification is not completed. The secondary pressure is applied (see the chain double-dashed line in FIG. 4). The time from the time point (T ₀ ) to the time point (T ₁ ) at which the forward movement of the pressurizing rod 62 ends is 0.1 when a rocker arm made of an aluminum alloy (JIS AC12 material) used in a valve mechanism of an internal combustion engine is obtained. 0.8 seconds (T ₁ -T ₀ = 0.1~0.8) it is must be. The place where the pressure bar 62 is pushed is a thick part of the product.

The secondary pressurizing pressure is applied until the molten metal in the cavity A is completely solidified, and then the pressurizing rod 62 is switched by switching the switching valve 74.
Are retracted (see FIG. 3).

However, when the molten metal 82 is filled in the cavity A, the molten metal 82 tries to enter the small gap portion B between the opening 26 and the pressure rod 62, but in this embodiment, the end of the opening 26 is closed. Part of the frustoconical wall
Since the 28 is formed, the molten metal 82 that has entered the ring-shaped space having a triangular cross section defined by the frustoconical peripheral wall 28 and the outer periphery of the tip of the pressure rod 62 has a large area and is movable in the movable die 24 and the pressure rod. In contact with 62, heat is taken away to rapidly solidify, and the advancing pressure of the molten metal 82 acts at a right angle on the truncated cone peripheral wall 28 to disperse the force, so that the molten metal 82 deeply enters the small gap portion B. It does not enter, and can effectively prevent the occurrence of flash.

Further, when the pressurizing rod 62 advances into the molten metal 82 and retracts after applying the secondary pressurizing pressure, the tip portion of the pressurizing rod 62 is cooled with respect to the movable mold 24 which is cooled and has a relatively low temperature. Is heated to a high temperature and expanded, and if it is a conventional mold, the pressure rod 62 and the opening 26
In this embodiment, the end of the aperture 26 is formed as a frustoconical peripheral wall 28, although there is a possibility that "gnawing" may occur with the peripheral wall of the pressure rod 62 or the pressure rod 62 may become stuck due to biting. Therefore, it is possible to prevent the pressure rod 62 from being reasonably guided into the opening 26 by the frusto-conical peripheral wall 28, and to prevent the pressure rod 62 from becoming stuck due to "biting" or biting.

Furthermore, when the pressure rod 62 enters the unsolidified molten metal 82, if the chamfer around the tip is not made,
There is a possibility that the “flow of hot water” generated by the displacement of the molten metal on the tip surface side will be locally accelerated at the corners around the tip and wrinkles will occur in the structure of the cast product. rod
Since the frusto-conical surface 63 is formed by chamfering around the tip of 62, such a problem can be avoided.

Further, the truncated cone surface 63 may be shaped so that the inclination angle (θ ₁ ) is 45 degrees, which is similar to the desired inclination angle of the truncated cone peripheral wall 28. By adopting such a shape, the truncated cone surface 63 and the truncated cone peripheral wall
The entering pressure of the molten metal that has entered the space defined by 28 and 28 is evenly distributed inside and outside, and the amount of molten metal entering the small gap between the pressure rod 62 and the opening 26 is reduced as much as possible. be able to.

EFFECTS OF THE INVENTION As is apparent from the above description, in the die casting apparatus of the present invention, the pressure rod opening formed through the mold wall faces the cavity end side around the opening end facing the inside of the cavity. Since it is formed as a circular truncated cone surface with a large hole diameter, and the chamfer around the tip of the pressure rod is performed, and the chamfer is formed as an inverted inclined circular truncated cone surface corresponding to the circular truncated cone surface, it is flush with the wall surface of the mold. When the molten metal is pressure-filled into the cavity of the die into which the pressure rod is retracted, the tip end surface of the pressure rod is flush with the wall surface of the die, Only the adjacent melts are cooled earlier than the melts adjacent to the wall surface of the mold and do not locally solidify.Therefore, the tip of the pressure rod is projected into the cavity to apply the secondary pressure. The pressure is transmitted to the entire molten metal in the cavity. As a result, a uniform and dense product is obtained, and the molten metal that has entered the annular space defined by the frusto-conical surface around the open end and the pressure rod is rapidly cooled and solidified, and the entry pressure is the truncated conical surface. The amount of penetration into the small gap between the opening and the pressure rod is sufficiently reduced, the occurrence of flashing is suppressed, and the galling of the mold due to flashing during mold release is prevented. It

Further, the truncated cone surface around the end of the opening serves as a guide surface when the pressure rod heated and expanded in the molten metal moves into and out of the aperture, and there is no galling between the die and the pressure rod. There is no possibility that the pressure rod will be caught at the end of the hole and will not move.

Furthermore, since the truncated cone surface is formed by chamfering around the tip of the pressure rod, when the pressure rod is pushed into the molten metal,
The phenomenon that the movement (flow) of the molten metal is locally disturbed is suppressed,
A cast product with a healthy internal structure is obtained.

Furthermore, in the present invention, since the frusto-conical surface around the opening end and the frusto-conical surface around the tip of the pressure rod have the same height in the advancing and retracting direction of the pressure rod, When the rod tip surface is retracted so that it is flush with the mold wall, the base edge of the truncated cone surface around the tip of the pressure rod occupies a position corresponding to the inner edge of the truncated cone surface around the opening end. When the mold is filled with the molten metal, the pressure of the molten metal is evenly distributed between the truncated cone surface around the opening end and the truncated cone surface around the tip of the pressure rod. The molten metal adjacent to the truncated conical surface of the open end and the molten metal adjacent to the conical surface of the tip of the pressure rod are cooled in substantially the same state, and the molten metal adjacent to both of the truncated conical surfaces solidifies uniformly, thus adding Secondary pressurization is evenly performed by pushing the pressure rod.

Moreover, since the height of the truncated cone surface around the hole end along the direction of advancing and retracting the pressure rod and the height of the tip of the pressure rod along the same direction of the frustoconical surface are the same, the occurrence of flashing flash is effective. This can be prevented, the number of processing steps after casting can be reduced, and the product yield can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of essential parts of a known die casting mold and a secondary pressure bar, and FIG. 2 is a schematic view of a die casting apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged view of a main part thereof, and FIG. 4 is a view showing a main part of a mold and a pressure rod in a state where a mold cavity is filled with molten metal. 10 ... Die casting machine, 12 ... Base, 14 ... Fixed platen, 16
… Fixed platen, 18… Connecting rod, 20… Movable platen, 22…
Fixed mold, 24 ... Movable mold, 26 ... Opening hole, 28 ... Frustum peripheral wall,
30 ... Holder, 32 ... Extrusion plate, 34 ... Holding rod, 36 ... Extrusion pin, 38 ... Extrusion hydraulic cylinder, 40 ... Push rod, 42 ... Movable platen drive hydraulic cylinder, 44 ... Push rod, 46 ... For injection Hydraulic cylinder, 48 ... Piston, 50 ... Injection ram, 52
… Support rod, 54… Injection sleeve, 56… Molten spout, 58… Holding rod, 60… Secondary pressure hydraulic cylinder, 62… Pressure rod, 63…
Truncated cone surface, 64 ... hydraulic control system, 66 ... hydraulic pump, 68 ... oil passage, 70 ... sequence valve, 72 ... oil passage, 74 ... switching valve, 76
... Flow rate adjusting valve, 78 ... Pressurizing rod advancing oil passage, 80 ... Pressurizing rod retracting oil passage, 82 ... Molten metal, A ... Cavity.

Claims (1)

[Scope of utility model registration request] 1. A mold is filled with molten metal, and a pressurizing rod that is flush with the wall surface of the mold before the molten metal is solidified is advanced into the cavity to form a secondary melt. A die-casting device of a type that exerts a pressurizing pressure, in which a hole diameter increases toward the cavity side at the periphery of the hole end where the hole for the pressure rod formed through the mold wall faces the inside of the cavity. It is formed as a circular truncated cone surface, and chamfering around the tip of the pressure rod is performed, and the chamfer is formed as an inverted inclined circular truncated cone surface corresponding to the opening end truncated cone surface. The die-casting device is characterized in that the frusto-conical surface around the tip of the rod has the same height in the advancing / retreating direction of the pressure rod.