JPH0999354A - Die for die casting and die casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the loading of sufficient pressure to molten metal in a cavity and to prevent the development of shrinkage in a casting by arranging a gate area changing means for changing the cross sectional area of a gate. SOLUTION: Hydraulic pressure is supplied into a die clamping cylinder and a piston rod is projected, and a male die 21 and a female die 23 are closed to execute the die clamping. Then, oxygen as active gas is fed into the cavity 29 and the air is replaced into the oxygen. Successively, an injection rod 43 is projected together with the piston rod of a hydraulic cylinder and the molten metal 30 in a sleeve 47 is pushed out with a plunger tip 45. The molten metal 30 is passed through a flow passage 31 and injected at high speed from the gate 55 whose cross sectional area is made to small, and formed as foggy state and stored into the cavity 29. Thereafter, since the cross sectional area of the gate 55 is made to large, the resistance of the gate 55 for injecting the molten metal 30 is made to small, and the sufficient pressure can be loaded to the molten metal 30 stored in the cavity 29 and the development of the shrinkage in the casting can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting mold and a die casting method, and in particular, the molten metal is injected in a state where the air in the cavity is replaced with an active gas such as oxygen to produce an aluminum or zinc alloy casting. The present invention relates to a die casting die and a die casting method.

[0002]

2. Description of the Related Art Generally, when casting is made of aluminum or the like, a die casting method is used in which molten metal in a sleeve is extruded by a plunger tip provided at the tip of an injection rod and injected into a cavity. Since the inert gas such as nitrogen existing in the sleeve and the cavity does not react with the molten metal, it causes porosity in the casting, which significantly deteriorates the quality of the casting. Therefore, in recent years, a die casting method has been performed in which the air in the cavity is replaced with an active gas such as oxygen to produce a casting such as aluminum or a zinc alloy. This die casting method is called the PF die casting method. In the PF die casting method, the cross-sectional area of the gate of the mold is made small, the speed of the molten metal injected from the gate is increased, the molten metal is atomized, and the reaction between the active gas such as oxygen and the molten metal is promoted. It prevents the formation of pores in the.

[0003]

However, in the PF die casting method, since the cross-sectional area of the gate is small, it is necessary to advance the plunger tip and apply sufficient pressure to the molten metal in the cavity after the molten metal has accumulated in the cavity. I can't. Therefore, there is a problem that shrinkage cavities are likely to occur in the casting. Further, since the gate has a small cross-sectional area, a large load is applied to the plunger tip and the sleeve, and the plunger tip and the sleeve cannot endure long-term use. Further, since the cross-sectional area of the gate is small and the molten metal is sprayed at a high speed, there is also a problem that the sprayed molten metal exerts a large impact on the mold and the mold cannot withstand long-term use. The present invention has been made in view of the above-mentioned conventional problems, it is possible to apply a sufficient pressure to the molten metal in the cavity, it is possible to prevent the occurrence of shrinkage cavities in the casting, moreover, the plunger tip and the sleeve An object of the present invention is to provide a die casting mold and a die casting method capable of preventing a large impact from being applied to the die without applying a large load.

[0004]

The invention of claim 1 is a die casting mold for injecting a molten metal from a gate to produce a casting in a state where at least the air in the cavity is replaced with an active gas. A die casting die comprising a gate area changing means for changing a cross-sectional area of the gate.

According to a second aspect of the present invention, in the first aspect, the gate area changing means is operable to move in and out of the gate, and a molten metal pressure detecting means for detecting the pressure of the molten metal. And a loading / unloading member actuating means for actuating the loading / unloading member in the direction of retracting from the gate when the pressure of the molten metal detected by the molten metal pressure detecting means exceeds a certain value. It is a type.

According to a third aspect of the present invention, in the first aspect, the gate area changing means is operable to move into and out of the gate, and a predetermined amount in a direction of projecting the in / out member. It is a die casting mold characterized by being constituted by an elastic body which is biased by a large force.

According to a fourth aspect of the present invention, in the first aspect, the gate area actuating means is capable of operating in a state of projecting to the gate and a state of retracting from the gate, and a time period after the molten metal is injected into the cavity. With a timer to measure
For die casting, characterized in that the timer comprises an inlet / outlet member operating means for operating the inlet / outlet member in a direction of retracting from the gate when it is measured that a predetermined time has elapsed since the molten metal was injected into the cavity. It is a mold.

A fifth aspect of the present invention is a die casting method for producing a casting by injecting a molten metal from a gate in a state where at least the air in the cavity is replaced with an active gas, and the pressure of the molten metal exceeds a certain value. The die-casting method is characterized by increasing the cross-sectional area of the gate.

A sixth aspect of the present invention is a die casting method for producing a casting by injecting a molten metal from a gate in a state where at least air in the cavity is replaced with an active gas, which is a predetermined time after being injected into the cavity. The die-casting method is characterized in that the cross-sectional area of the gate is increased after a lapse of time.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a die casting machine 3 on which a die casting die 1 according to a first embodiment of the present invention is mounted. The die casting machine 3 is for producing an aluminum casting. Reference numeral 5 indicates a base,
A pair of fixed plates 7 and 9 are attached to the base 5 so as to face each other. Tie bars 11 are inserted into and fixed to the four corners of the fixed plates 7 and 9, respectively.

A movable plate 13 is slidably provided on the tie bar 11, and the movable plate 13 is a sliding plate 1 of the base 5.
5 is installed. A mold clamping cylinder 17 is attached to the fixed platen 7, a guide bar 19 is connected to a piston rod of the mold clamping cylinder 17, and a tip of the guide bar 19 is connected to the movable platen 13. The mold clamping cylinder 17 causes the movable platen 13 to move toward and away from the fixed platen 9.

A male die 21 is attached to the front surface of the movable platen 13, and a female die 23 is attached to the front surface of the fixed platen 9. The male die 21 and the female die 23 form a die casting die 1. An extrusion cylinder 33 is attached to the back surface of the movable platen 13. Extrusion cylinder 33
A rod member 35 is connected to the piston rod of, and the tip of the rod member 35 penetrates the male die 21.

Reference numeral 37 indicates a hydraulic cylinder, which is attached to a base frame 39 fixed to the base 5. A tie-lot-shaped or frame-shaped connecting member 41 is attached to the hydraulic cylinder 37, and the connecting member 41 is connected to the back surface of the fixed platen 9. The injection rod 43 is connected to the piston rod of the hydraulic cylinder 37, and the tip of the injection rod 43 is provided with a plunger tip 45. The sleeve 47 is attached so as to penetrate the fixed platen 9.
The tip of 7 is fitted in the female mold 23. The plunger tip 45 provided at the tip of the injection rod 43 enters the sleeve 47.

The die casting mold 1 will be described in detail with reference to FIG. The die casting die 1 shows a state in which the male die 21 and the female die 23 are closed. Reference numeral 29 indicates a cavity, which is the male mold 21.
The recess 25 formed in the female mold 23 and the recess 25 formed in the female mold 23.
7 and. A gate 55 communicates with the cavity 29, and the gate 55 communicates with the inside of the sleeve 47 via the flow path 31. Reference numeral 51 indicates a gate cylinder as an in-and-out member operating means, and the gate cylinder 51 is provided in the female die 23. An inlet / outlet member 53 is fixed to the piston rod of the gate cylinder 51, and the inlet / outlet member 53 can operate in a state of protruding to the gate 55 and a state of retracting from the gate 55.

The female die 23 of the die casting die 1 is provided with a pressure sensor 57 as a molten metal pressure detecting means for detecting the pressure of the molten metal 30, and the pressure sensor 57 detects the pressure of the molten metal 30 in the sleeve 47. To do. Pressure sensor 57
Is connected to a switching valve (not shown) of the gate cylinder 51 via a control panel 59, and when the pressure of the molten metal 30 in the sleeve 47 becomes a certain value or more, the switching valve of the gate cylinder 51 operates and the gate cylinder 51 The piston rod of is set to retract. The pressure sensor 57, the loading / unloading member 53, and the gate cylinder 51 constitute a gate area changing unit.

The die casting method by the die casting machine 3 having the die casting die 1 mounted thereon will be described. Accessory member 5
Reference numeral 3 projects to the gate 55, and the cross-sectional area of the gate 55 is smaller than that in the state where the loading / unloading member 53 is retracted from the gate 55. Hydraulic pressure is supplied to the mold clamping cylinder 17, the piston rod of the mold clamping cylinder 17 projects, and the movable platen 7
Moves toward the fixed platen 9, the male die 21 and the female die 23 are closed, and the die is clamped. And cavity 2
Oxygen as an active gas is fed into the cavity 9 and the cavity 2
The air in 9 is replaced with oxygen.

Next, the injection rod 43 projects together with the piston rod of the hydraulic cylinder 37, and the plunger tip 45
The molten metal 30 in the sleeve 47 is pushed out by. Molten metal 30
Passes through the channel 31 and has a smaller cross-sectional area.
It is injected from 5 at high speed. As shown in FIG. 3, the gate 5
The molten metal 30 injected from No. 5 becomes a mist, reacts with oxygen, and collects in the cavity 29.

When the molten metal 30 accumulates in the cavity 29, the pressure of the molten metal 30 in the cavity 29 rises. When the pressure of the molten metal 30 in the sleeve 47 rises and the pressure of the molten metal 30 in the sleeve 47 becomes a certain value or more, the pressure sensor 5
7 detects this, and as shown in FIGS. 4 and 5, the switching valve of the gate cylinder 51 is actuated, the piston rod of the gate cylinder 51 is retracted, the withdrawal member 53 is retracted from the gate 55, and the gate 55 Increase the cross-sectional area. Then, the plunger tip 45 is advanced together with the injection rod 43 by a boost mechanism (not shown), and the sleeve 47
The molten metal 30 in the cavity 29 is pressed to melt the molten metal 30 in the cavity 29.
Apply sufficient pressure to.

As described above, the molten metal 3 is placed in the cavity 29.
Since the cross-sectional area of the gate 55 is increased after 0 is accumulated, the resistance of the gate 55 from which the molten metal 30 is injected can be reduced, and sufficient pressure can be applied to the molten metal 30 accumulated in the cavity 29. Therefore, it is possible to prevent shrinkage cavities from occurring in the casting.

After the molten metal 30 in the cavity 29 is solidified, the piston rod of the mold clamping cylinder 17 is retracted and the mold clamping is released, and the movable platen 13 moves in the direction away from the fixed platen 9 to make the die casting mold. 1 is opened. Then, the piston rod of the extrusion cylinder 33 projects and the casting is extruded from the male die 21 and taken out by a take-out robot (not shown). The die casting machine 3 repeats the above-mentioned operation to produce a casting.

In the die casting mold 1, the pressure sensor 57 has a structure for detecting the pressure in the sleeve 47, but it may have a structure for detecting the pressure in the cavity 29. The pressure in the cavity 29 after the oxygen reacts with the molten metal 30 and oxygen is consumed is detected by the pressure sensor 57, and before the molten metal 30 is filled in the cavity 29, the inlet / outlet member 53 is connected to the gate 55. Back from the gate 5
The cross-sectional area of 5 may be increased. With such a configuration,
The gate 55 is filled before the cavity 29 is filled with the molten metal 30.
The molten metal 30 injected from the machine is decelerated, and damage to the mold, sleeve, plunger chip, etc. can be reduced.

FIG. 6 shows a die casting mold 63 according to the second embodiment. The die casting die 63 is mounted on the die casting machine 3. Since the die casting mold 63 has the same components as the die casting mold 1 according to the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted. Further, the manufacturing process of the casting by the die casting machine 3 is also the same, and therefore the description of the same process will be omitted.

The die casting die 63 will be described. As shown in FIG. 6, the female die 65 of the die casting die 63 is provided with a plurality of disc springs 67 as elastic bodies stacked one on top of the other. The plurality of disc springs 67 urge the loading / unloading member 53 in a direction projecting toward the gate 55 with a force of a predetermined magnitude, so that the cross-sectional area of the gate 55 is reduced. The disc spring 67 and the moving member 53 constitute a gate area changing unit.

A die casting method by the die casting machine 3 having the die casting die 63 mounted thereon will be described. The loading / unloading member 53 has the disc spring 6 before the die casting machine 3 is started.
It is made to project to the gate 55 by the elastic force of 7. After replacing the air in the cavity 29 with oxygen, melt 3
0 is supplied to the cavity 29. As shown in FIG. 7, the molten metal 30 accumulates in the cavity 29, and the pressure of the molten metal 30 in the cavity 29 rises.
Is retracted against the elastic force of the disc spring 67, and the gate 5
The cross-sectional area of 5 becomes large. Then plunger tip 45
Thus, the molten metal 30 in the sleeve 47 is pressed to apply pressure to the molten metal 30 in the cavity 29.

FIG. 8 shows a die casting mold 69 according to the third embodiment. The die casting die 69 is mounted on the die casting machine 3. Since the die casting mold 69 has the same components as those of the die casting mold 1 according to the first embodiment, the same components are designated by the same reference numerals, and the description thereof will be omitted. Since the manufacturing process of the casting according to No. 3 is the same, the description of the similar process will be omitted.

The die casting die 69 will be described. The die casting machine 3 is provided with a timer 71 that measures the time after the molten metal 30 is injected into the cavity 29 by the plunger tip 45. The timer 71 detects the time when the switching valve 73 of the hydraulic cylinder 37 first operates in the die casting machine 3 and starts measuring time. When the timer 71 measures that a predetermined time has elapsed, the switching valve of the gate cylinder 51 is actuated, the piston rod of the gate cylinder 51 retracts, and the loading / unloading member 53 retracts from the gate 55. The predetermined time is the time until the oxygen in the cavity 29 reacts with the molten metal 30 and the oxygen in the cavity 29 is consumed, and is determined by the size, shape, temperature of the molten metal, etc. of the cavity 29. It A timer 71, an entrance / exit member 53,
The gate cylinder 51 and the gate area changing unit are configured.

A die casting method by the die casting machine 3 having the die casting die 69 mounted thereon will be described. Before the die casting machine 3 is started, the loading / unloading member 53 has the gate 5
It projects to 5. After replacing the air in the cavity 29 with oxygen, the switching valve 73 of the hydraulic cylinder 37 is actuated, the injection rod 43 and the plunger tip 45 are driven, and the molten metal 30 is supplied to the cavity 29. The timer 7 is interlocked with the operation start of the switching valve 73 of the hydraulic cylinder 37.
1 starts measuring time.

When it is measured by the timer 71 that the predetermined time has elapsed, the switching valve of the gate cylinder 51 is actuated, the piston rod of the gate cylinder 51 is retracted, the withdrawal member 53 is retracted from the gate 55, and the gate 55 is retracted. The cross-sectional area of 55 becomes large. The decelerated melt 30 is injected from the gate 55 having a large cross-sectional area, and the melt 30 is supplied into the cavity 29. Therefore, it becomes possible to prevent the die casting die 69 from being impacted, and the die casting die 69 can withstand long-term use. Further, it becomes possible to prevent a large load from being applied to the plunger tip 45 for pushing out the molten metal 30 in the sleeve 47 and the sleeve 47.
And the sleeve 47 will endure long-term use. Further, it becomes possible to apply a sufficient pressure to the molten metal 30 in the cavity 29.

Although the embodiment of the present invention has been described in detail above, the specific configuration is not limited to this embodiment, and there are changes in the design without departing from the gist of the present invention. Are also included in the present invention. For example, the material forming the casting may be a zinc alloy or the like.

[0030]

As described above, according to the present invention, sufficient pressure can be applied to the molten metal in the cavity, shrinkage cavities can be prevented from occurring in the casting, and the quality of the casting can be improved. Like Further, a large load is not applied to the plunger tip and the sleeve, a large impact can be prevented from being applied to the die, and the plunger tip, the sleeve and the die can endure long-term use.

[Brief description of drawings]

FIG. 1 is a side view of a die casting machine on which a die casting mold according to an embodiment of the present invention is mounted.

FIG. 2 is a cross-sectional view of a die casting mold according to the first embodiment of the present invention.

FIG. 3 is a partially enlarged view of the die casting mold according to the first embodiment of the present invention.

FIG. 4 is a sectional view for explaining the operation of the die casting mold according to the first embodiment of the present invention.

FIG. 5 is a partially enlarged view of the die casting mold according to the first embodiment of the present invention.

FIG. 6 is a sectional view of a die casting mold according to a second embodiment of the present invention.

FIG. 7 is a sectional view for explaining the operation of the die casting mold according to the second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a die casting mold according to a third embodiment of the present invention.

[Explanation of symbols]

 1, 63, 69 Die casting mold 3 Die casting machine 5 Base 7, 9 Fixed plate 11 Tie bar 13 Movable plate 15 Sliding plate 17 Mold clamping cylinder 19 Guide bar 21 Male mold 23, 65 Female mold 25, 27 Recess 29 Cavity 30 Molten Metal 31 Flow Channel 33 Extrusion Cylinder 35 Rod Member 37 Hydraulic Cylinder 39 Frame 41 Connection Member 43 Injection Rod 45 Plunger Chip 47 Sleeve 51 Gate Cylinder 53 Inlet / Outlet Member 55 Gate 57 Pressure Sensor 59 Control Panel 67 Disc Spring 71 Timer 73 Switching Valve

Claims (6)

[Claims] 1. A die casting die for producing a casting by injecting a molten metal from a gate with at least air in the cavity being replaced by an active gas, the gate area changing a cross-sectional area of the gate. A die casting mold comprising a changing means. 2. The gate area changing means according to claim 1, wherein the gate area changing means is operable to move into and out of the gate, a melt pressure detecting means for detecting the pressure of the melt, and the melt pressure. A die casting mold, comprising: an inlet / outlet member operating means for operating the inlet / outlet member in a direction of retracting from the gate when the pressure of the molten metal detected by the detector is equal to or higher than a certain value. 3. The gate area changing means according to claim 1, wherein the gate area changing means is operable with a state of projecting to the gate and a state of retracting from the gate, and a force of a predetermined magnitude in a direction of projecting the inlet / outgoing member. A die-casting die, comprising a resilient elastic body. 4. The gate area actuating means according to claim 1, wherein the gate area actuating means is operable to move into and out of the gate, and a timer for measuring the time after the molten metal is injected into the cavity. A die-casting means for activating the loading / unloading member in the direction of retracting from the gate when the timer measures that a predetermined time has elapsed since the molten metal was injected into the cavity. Mold for. 5. A die casting method for producing a casting by injecting molten metal from a gate with at least the air in the cavity being replaced by an active gas, wherein the gate is disconnected after the pressure of the molten metal exceeds a certain value. Die casting method characterized by increasing the area. 6. A die casting method for producing a casting by injecting a molten metal from a gate in a state where at least the air in the cavity is replaced with an active gas, the method comprising the steps of: Die casting method characterized by increasing the cross-sectional area.