JPH084916B2 - Molten metal forging method and device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molten metal forging method and apparatus for forging by injecting molten metal into a cavity of a mold and pressurizing the molten metal.

[Conventional technology]

For example, molten metal forging of an aluminum disk wheel for automobiles is often performed by a vertical injection device due to a relatively small amount of gas entrainment at the time of injection of the molten metal. And the like disclosed by JP-A-63-140747 are known.

This vertical injection device includes a lower mold fixed to a horizontal surface on the machine base side, and an upper mold supported so as to be vertically movable so that the mold clamping mold is opened with respect to the lower mold, It is equipped with a plurality of cores located outside the upper mold and movable in the horizontal direction.If the molded product is a disc wheel, the cross section is approximately the same between the facing surfaces of these molds and the core. A cavity is formed by a V-shaped tubular rim-corresponding portion and a substantially disk-shaped disc-corresponding portion. The lower mold is formed with a fixed sleeve that communicates with the disk equivalent part of the cavity through the runner, and the injection sleeve on the injection cylinder side is detachably joined to this fixed sleeve. A gas venting device driven by an air cylinder is connected to the rim equivalent part.

With this structure, the upper mold is lowered together with the closed core to clamp the mold, and then the injection sleeve filled with the molten metal is joined to the fixed sleeve, and the plunger tip is advanced in the injection sleeve. Then, the molten metal in the injection sleeve is injected into the cavity through the fixed sleeve and the runner, and is filled from the portion corresponding to the disk toward the tip of the portion corresponding to the rim. At the time of filling, the gas in the cavity is released to the outside of the mold by a gas release device. One injection cycle is completed by waiting for the filled molten metal to solidify, opening the mold, opening the core raised together with the upper mold, and extruding the solidified product from the upper mold.

[Problems to be Solved by the Invention]

However, in such a conventional vertical injection apparatus, the plunger pressure of the injection cylinder is not sufficiently transmitted to the tip of the rim-corresponding portion of the cavity when the molten metal is filled into the cavity, and sinkholes and the like are likely to occur, There is a problem that a dense product close to a satisfactory forged structure cannot be obtained.

[Means for solving the problem]

In order to solve such a problem, the molten metal forging method according to the present invention comprises a plurality of horizontally movable movable upper and lower molds from the start of the filling of the molten metal into the mold cavity to the completion of the filling. The outer peripheral surface of the taper formed on the lower side of the outer peripheral portion of the core so that the outer diameter becomes smaller toward the lower side contacts the inner peripheral surface of the taper ring that is placed at the outer position of the core during mold clamping. And a low pressure in the low pressure mold clamping state so that a narrow horizontal gap is formed between the upper surface of the outer periphery of the lower mold and the horizontal surface of the lower end of the core, which communicates with the outside air from the lower end of the cavity. The molten metal is injected into the cavity by injection, and the hydraulic control device is immediately switched to apply high pressure to both the mold clamping cylinder and the injection cylinder at the same time when the molten metal is completely filled into the cavity, the horizontal gap is closed, and Of the core So that exert a feeder force on the molten metal in the cavity in the lower surface of the non-vertical surfaces and the upper mold which is formed on the peripheral lower side.

Further, the molten metal forging device according to the present invention comprises an upper die, a lower die, and a plurality of horizontally movable cores forming a cavity between these die, and the outer periphery of all of these cores. A tapered outer peripheral surface is provided on the lower side of the part so that the outer diameter becomes smaller toward the lower side, and a taper ring is arranged at an outer position of the tapered outer peripheral surface of this core when the mold is clamped. The inner diameter becomes smaller toward the upper side, and when the core is descending, the tapered outer peripheral surface of the core is brought into contact with the inner peripheral surface of the taper to restrict the downward movement while promoting the downward movement of the core. Is provided between the upper surface of the outer peripheral portion of the lower mold and the lower horizontal surface of the core so as to communicate the cavity with the outside air at the time of low-pressure mold clamping, and has a gap to close at the time of high-pressure mold clamping, and the mold clamping cylinder and the injection cylinder. And in the cavity Until completion of the molten metal filling those incorporating a hydraulic control device for switching immediately to exert simultaneously a high pressure upon completion melt filled into the cavity by the action of low pressure.

[Action]

According to the present invention, since the mold is clamped at a low pressure until the molten metal is completely filled, the upper mold and the core are in close contact with each other. Due to the reaction force due to the contact with the inner peripheral surface of the taper processing on the upper side of the inner peripheral part, it does not descend sufficiently, and as a result, a horizontal gap is created at the joint between the core and the lower mold, and the gas in the cavity is released from this gap. It

In addition, the mold clamping force increases with the completion of the filling of the molten metal to close the horizontal gap, and the core moves in the diameter reducing direction by the reaction force of the wedge action due to the sliding contact of the tapered surface with the taper ring. Since the molten metal in the cavity is compressed and pressurized and is subjected to the feeding action, the molten metal is sufficiently spread to the tip of the rim-corresponding portion of the cavity, and the structure becomes dense.

〔Example〕

1 to 5 show an embodiment of a molten metal forging apparatus according to the present invention shown for explaining a molten metal forging method according to the present invention. FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is die bonding. Fig. 3 is an enlarged vertical sectional view of the portion corresponding to the rim of the cavity, and Fig. 4 is a relational line between time (elapsed time from the start of molten metal filling) and hydraulic pressure of both injection and mold clamping cylinders. Figure, fifth
The figure is a hydraulic circuit diagram. In the figure, a lower mold 2 is fixed on a horizontal surface of a machine base 1, and an upper mold 3 is provided above the lower mold 2 by a mold clamping cylinder 4 shown in FIG. On the other hand, it is supported so that it can be moved up and down in the vertical direction so that the mold can be opened. Outside the upper mold 3, a plurality of cores 5 are arranged in parallel in the circumferential direction of the upper mold 3, and these cores 5 ascend and descend integrally with the upper mold 3 and are not shown when rising. The cylinders are configured to be driven forward and backward in synchronization with each other. If the molded product is a disc wheel, the rim-corresponding portion 6a having a cross-section with a substantially cylindrical shape and the disc-shaped disc having a disc shape are provided between the opposing surfaces of the molds 2 and 3 and the core 5. A cavity 6 including the portion 6b is formed. The lower mold 2 has a portion corresponding to the disk of the cavity 6.
A fixed sleeve 8 is formed which communicates with 6b via a runner 7. An injection sleeve 9 is detachably joined to the fixed sleeve 8, and the injection sleeve 9 is designated by the reference numeral in FIG. A plunger tip 11a, which is a head of a plunger 11 that moves forward and backward by an injection cylinder shown by 10, is fitted so as to move forward and backward. Then, melt 12 in the injection sleeve 9
Is injected and the plunger tip 11a is moved forward, so that the molten metal 12 is filled in the cavity 6. Further, an annular taper ring 13 is fixedly disposed on the machine base 1 side outside the core 5, and an inner circumference thereof is downwardly directed downward on an outer peripheral portion of the core 5. The tapered outer peripheral surface, which is a tapered surface formed so as to have a small outer diameter, is in contact with the core 5 when the core 5 descends, thereby restricting the downward movement of the core 5 while promoting the downward movement of the core 5. A tapered inner peripheral surface 13a is formed as a tapered surface, and is configured so as to restrict outward movement of the core 5 when the core 5 descends.
Then, the mold clamping force is reduced to a low pressure to lower the core 5 together with the upper mold 3, and when the tapered surface 5a comes into contact with the tapered surface 13a of the taper ring 13 and stops, the core 5 and the lower mold 2 Below the outer periphery of the lower end of the cavity 6 of the mold joining portion between the cores, for example, about 0.1 to 0.2 mm indicated by reference numeral t1 in the figure, that is, from the relationship between the tapered surfaces 13a, 5a of the taper ring 13 and the core 5, A gap is formed so that a gap is generated even when the lower side of 5 is reduced in diameter, and a gap that allows gas such as air to pass through but does not allow molten metal to pass through is formed, and between the horizontal plane between the core 5 and the lower mold 2. , A horizontal gap that communicates with the outside air is formed following the gap t ₁ indicated by reference numeral t. The horizontal clearance t is configured to be closed by the pressure and the action of the tapered surfaces 5a and 13a when the mold clamping force is increased.

Here, the hydraulic circuit of this device will be described with reference to FIG. A pipe 24 provided with a relief valve 20 and a check valve 21 and connected to a plurality of pumps 22 and a tank 23 is connected to an accumulator 25 and a switching valve 26, and a pipe branched from the switching valve 26. The pipe 27 and the pipe 28 are connected to the injection cylinder 10, the rod end chamber 10a, and the head end chamber 10b, respectively. A switching valve 29 and a flow control valve 30 are provided on the pipe 27, and the switching valve 29 and the pipe 28 are check valves.
They are connected by a pipe 32 provided with 31. On the other hand, relief valve
A pipe 36, which is provided with 33 and a check valve 34 and is connected to the pump 35 and the tank 23, is connected to the pressurizing chamber 4a of the mold clamping cylinder 4, and in this pipe 36, a flow path is provided by the pump 35. A switching valve 37 for switching between the side and the tank 23 side is provided. Reference numeral 38 is a pipe that has a check valve 39 and connects the pipes 36 and 24.

The operation of the molten metal forging device configured as above will be described. High-pressure oil is stored in the accumulator 25 by the operation of the pump 22, and the accumulator 25 is closed. When the switching valve 37 is switched to the pump 35 side in this state and the pump 35 operates, oil is sent to the pressurizing chamber 4a of the mold clamping cylinder 4, and the upper mold 3 descends with the closed core 5. Thus, the mold is clamped. In this case, the tapered surface 5a of the core 5 comes into contact with the tapered surface 13a of the taper ring 13, and the reaction force and the hydraulic pressure regulated by the relief valve 33 balance each other, so that the lower mold 2 and the core 5 have a low pressure. It is clamped with. At this time, gaps t and t ₁ are formed between the planes of the lower mold 2 and the core 5 and below the lower end outer peripheral portion of the cavity 6 so that the cavity 6 communicates with the outside.

After the molten metal 12 is supplied into the injection sleeve 9 and the injection sleeve 9 is joined to the fixed sleeve 8 in such a low-pressure mold clamping state, the switching valve 26 is switched to the pipe 28 side and the pump 22 operates. , Head end chamber of injection cylinder 100 1
Since oil is sent to 0b and the plunger tip 11a moves forward,
The molten metal 12 passes through the fixed sleeve 8 and the runner 7 and then into the cavity 6
It is injected and filled in. At this time, a narrow gap t ₁ is formed between the lower mold 2 and the core 5 so that the molten metal 12 does not easily pass through and only the gas passes, and between the lower mold 2 and the core 5 is a horizontal plane. The clearance t ₁ that allows communication between the clearance t ₁ and the outside air
However, the gas in the cavity 6 is discharged to the outside through the gap t ₁ and the gap t. Also, if the plunger pressure at this time is too high, the flash will blow out, so it is set to a small value.

When the filling of the molten metal 12 is completed and the reaction force of injection begins to increase, the accumulator 25 opens and high-pressure oil is sent to the mold clamping cylinder 4 and the injection cylinder 10, and the injection pressure and the mold clamping pressure increase at the same time. Is pressed. The high-pressure oil supply to the mold clamping cylinder 4 increases the mold clamping force to close the clearance t, and at the same time, the clearance t ₁ is closed by the action of the tapered surfaces 5a and 13a. At this time,
Since the molten metal 12 in the cavity 6 is compressed and pressurized by the increase of the mold clamping force, the molten metal 12 spreads to every corner of the cavity 6. In particular, when the rim-corresponding portion 6a of the cavity 6 is formed into a generally cross-sectional shape and the inclined surface of the molten metal 12 is compressed as shown by the chain line in FIG. Since the distance is small, pressure is also applied to the tip of the rim-corresponding portion 6a to act as a feeder, and a dense product without cavities can be obtained. Further, as described above, since the injection pressure is also increased at the same time as the mold clamping pressure, even if the molten metal 12 is pressurized, the molten metal 12 does not flow back to the plunger tip 11a side.
Furthermore, since the pressure is increased in a short time by using the accumulator 25, the molten metal 12 is not cooled. Therefore, according to such a configuration, the rim-corresponding portion 6b of the cavity 6 has a substantially V-shaped cross section, such as the aluminum automobile disc wheel illustrated in FIG. A cast product, or a cast product in which a tapered inner peripheral surface whose outer diameter increases downward is provided below the inner peripheral portion of the core 5 forming the outer peripheral surface side of the cavity 6. It is particularly useful when molding.

By waiting for the molten metal 12 filled in this way to solidify, the mold is opened, the core that has risen together with the upper mold 3 is opened, and the solidified product is extruded from the upper mold 3 to perform one injection cycle. finish.

FIG. 4 is a diagram showing the time (elapsed time from the start of molten metal filling) on the horizontal axis and the hydraulic pressure between the mold clamping cylinder and the injection cylinder on the vertical axis. The state is shown in which the mold clamping pressure and the injection pressure are kept low until the filling is completed, and both of these pressures are made high in a short time at the same time when the filling is completed.

〔The invention's effect〕

As described above, according to the molten metal forging method of the present invention, from the start of filling the molten metal into the mold cavity to the completion of filling, a plurality of cores that are horizontally movable between the upper and lower molds are used. The outer peripheral surface of the taper formed on the lower side of the outer peripheral portion of the taper has a smaller outer diameter and is in contact with the inner peripheral surface of the taper ring arranged at the outer position of the core during mold clamping. In addition, by low pressure injection under low pressure mold clamping condition, a narrow gap is formed between the upper surface on the outer peripheral side of the lower mold and the horizontal surface on the lower end side of the core, and a horizontal gap is formed from the lower end of the cavity to the outside air. Fill the cavity with the molten metal, and immediately switch the hydraulic control device so that high pressure is simultaneously applied to both the mold clamping cylinder and the injection cylinder when the molten metal is completely filled into the cavity, the horizontal gap is closed, and the core Inner circumference With the lower surface of the non-vertical surfaces and the upper mold which is formed on the side so that exert a feeder force on the molten metal in the cavity.

Further, according to the molten metal forging apparatus according to the present invention, a plurality of horizontally movable cores that form a cavity between the upper die and the lower die are provided, and all the cores are provided on the lower side of the outer peripheral portion. Provide a tapered outer peripheral surface that reduces the outer diameter downward, and place a taper ring on the outer peripheral surface of the tapered outer peripheral surface of this core during mold clamping. The inner diameter of the core becomes smaller toward the lower end of the core, and when the core is descended, the tapered outer peripheral surface of the core is brought into contact with the inner peripheral surface of the core for restricting the downward movement while accelerating the downward movement of the core. A cavity is formed between the upper surface of the outer periphery of the lower mold and the lower horizontal surface of the core to communicate the cavity with the outside air during low-pressure mold clamping, and a cavity is provided between the mold clamping cylinder and the injection cylinder. Molten metal Since Hama to completion and to incorporate a hydraulic control device for switching immediately to exert simultaneously a high pressure at the time of melt completion of filling into the cavity by the action of low pressure, an excellent effect described below.

That is, according to the present invention, the mold is clamped at a low pressure until the completion of the filling of the molten metal, and the upper mold and the core are in close contact with each other. The reaction force from the contact with the inner peripheral surface on the upper side of the inner peripheral part of the tool does not allow it to descend sufficiently, and the gas in the cavity can be discharged from the horizontal gap formed at the joint between the core and the lower mold. it can.

Further, according to the present invention, as the mold clamping force increases with the completion of the molten metal filling, the horizontal gap is closed, and the core is reduced in diameter by the wedge action due to the sliding contact between the tapered ring and the tapered surface. Direction, the molten metal in the cavity is compressed and is subjected to the pressing action, and the molten metal is fully spread to every corner of the cavity, and is a good quality cast product with a dense forged structure without cavities. Can be obtained.

[Brief description of drawings]

1 to 5 show an embodiment of a molten metal forging apparatus according to the present invention shown for explaining a molten metal forging method according to the present invention. FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is die bonding. 3 is an enlarged vertical sectional view of the portion corresponding to the rim of the cavity, and FIG. 4 is time (elapsed time from the start of molten metal filling).
FIG. 5 is a hydraulic circuit diagram showing the relationship between the oil pressures of the injection and mold clamping cylinders, and FIG. 2 ... Lower mold, 3 ... Upper mold, 4 ... Mold clamping cylinder, 5
…… Core, 5a, 13a …… Tapered surface (tapered outer peripheral surface, taper inner peripheral surface), 6 …… Cavity, 10 …… Injection cylinder, 12 …… Melted metal, 13 …… Tapered ring, t, t ₁ ...
… Gap,

Claims (2)

[Claims] 1. An upper die, a lower die, and a plurality of horizontally movable cores that form a cavity between the upper die and the lower die. The cores are provided below the outer peripheral portions of all the cores. A tapered outer peripheral surface is provided so that the outer diameter becomes smaller, and a taper ring is arranged at an outer position of the tapered outer peripheral surface of the core when the mold is clamped. The inner diameter of the core becomes smaller and the tapered outer peripheral surface of the core is brought into contact with the core when the core descends, and the inner peripheral surface of the taper is provided to restrict the downward movement while accelerating the downward movement of the core. A gap is formed between the lower die and the lower end horizontal surface of the core so that the cavity communicates with the outside air at the time of low-pressure mold clamping, and a gap is provided to close at the time of high-pressure mold clamping, and the mold clamping cylinder and the injection cylinder are connected to the inside of the cavity. Low until completion of molten metal filling By using a molten metal forging device provided with a hydraulic control device that immediately switches so that high pressure is simultaneously applied when the molten metal is completely filled in the cavity, from the start of the filling of the molten metal in the cavity to the completion of filling of the core. The tapered outer peripheral surface is in contact with the tapered inner peripheral surface of the taper ring, and is narrowed between the outer peripheral upper surface of the lower die and the horizontal surface on the lower end side of the core to communicate with the outside air from the lower end of the cavity. The cavity is filled with molten metal by low-pressure injection under low-pressure mold clamping so that a horizontal gap is formed.When the molten metal is completely filled in the cavity, high pressure is simultaneously applied to both the mold clamping cylinder and the injection cylinder. Immediately, the horizontal gap is closed, and the non-vertical surface formed on the lower side of the inner peripheral portion of the core and the lower surface of the upper mold melt the cavity. Squeeze casting method is characterized in that so as to exert a feeder force. 2. A molten metal forging apparatus comprising an upper die and a lower die, and a plurality of horizontally movable cores that form a cavity between the upper die and the lower die. A tapered outer peripheral surface is provided on the lower side of the outer peripheral portion so that the outer diameter is reduced downward, and a taper ring is arranged at an outer position of the tapered outer peripheral surface of this core when the mold is clamped. Inside the taper processing where the inner diameter becomes smaller toward the upper side of the part and when the core is lowered, the outer peripheral surfaces of the core are brought into contact with each other and the downward movement of the core is restricted while promoting the downward movement of the core. A peripheral surface is provided, and a gap is formed between the upper surface of the outer peripheral portion of the lower mold and the lower end horizontal surface of the core so as to communicate the cavity with the outside air at the time of low pressure mold clamping, and the mold clamping is performed. Cylinder and injection cylinder The molten metal forging device is characterized in that a hydraulic control device is incorporated so that a low pressure is applied until the molten metal is completely filled in the cavity, and a high pressure is immediately applied when the molten metal is completely filled in the cavity.