JPH09239512A - Liquid phase injecting formation of metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the fluidity and to improve the quality of a formed product by using a cylinder head nozzle as a self closing nozzle and holding a metal in the nozzle in liquid phase, when forming the metal in a liquid phase by using an inline screw type injection forming machine. SOLUTION: A cylinder head 2 is fitted to the tip part of an injection forming machine cylinder 1 with bolts 17. The nozzle 3 having an opening hole 3a at the tip part of this cylinder head 2, is screwed and plural flowing passages 14 for communicating the inner part of the cylinder 1 inserted with a screw 15 with the inner part of the nozzle 3 is provided. Further, hole 5a in the vertical direction is bored at the tip end side of the cylinder head 2, and hole 4a vertically communicated with the hole 5a is bored at the tip center part inserting a rotary shaft to insert a needle valve 4 shiftable frontward/rearward. The tip part of the needle valve 4 can be inserted into the nozzle opening hole 3a and the rear end is abutted on a rotary shaft 5. Further, heaters 16 are fitted to the outer peripheries of the nozzle 3, cylinder head 2 and cylinder 1 to execute the temp. control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-phase injection molding method for a metal, in which a metal is melted by an in-line screw type injection molding machine to form a liquid phase, which is then injected into a mold for molding.

[0002]

2. Description of the Related Art Conventionally, a metal forming method which has been used is a cold chamber method in which a metal is melted in a melting furnace, a molten metal is drawn by a ladle and put in a chamber, and a mold is cast in the melting furnace. There is a die casting method represented by the installed hot chamber method. However, since the conventional die casting method uses a melting furnace, it requires a large amount of melting energy to melt the metal, and at the same time,
There is a problem that the working environment is bad because high heat and dust are generated. Therefore, in recent years, attention has been paid to a metal injection molding method using an injection molding machine.

In this metal injection molding method, the metal is kneaded and melted by a screw having a non-return prevention mechanism at the tip end,
In this method, the molten metal is supplied to the front of the screw, the screw is retracted, the screw is advanced, and the screw is injected into a mold for molding. In this injection molding method, since the molten metal has a very low viscosity, it is necessary to block the opening hole of the nozzle to prevent the molten metal from flowing out when the metal is kneaded and melted by the screw. Therefore, conventionally, as shown in FIG. 7, a method of positively forming the solid plug D in the opening hole of the nozzle 3 has been adopted. In order to form this solid plug D, the temperature of the nozzle 3 is set low, so that the solid plug (solid) D and the molten metal (liquid) are formed at the tip of the nozzle 3.
A semi-solidified structure F in which solid and liquid coexist is formed between E and E. In the injection molding method using the thixomold method, the molten metal (liquid) E region also has the semi-solidified structure F.

[0004]

In the conventional metal injection molding method, the fixing plug formed at the tip of the nozzle is
There were the following problems. (A) Since the injection pressure changes due to the variation in the size of the formed fixing plug or the fixing plug interferes with the flow of the molten metal, it is often difficult for the molten metal to quickly enter the mold cavity. appear. (B) In order to prevent the fixed plug from entering the mold cavity, a catcher for the fixed plug is provided in the mold, but the fixed plug does not stably enter the catcher and pops out inside the mold cavity. It often happens that it breaks into. (C) Since there is a semi-solidified structure in which a solid and a liquid having extremely poor fluidity coexist, a large flow resistance is generated in a narrow channel portion or a gate portion when injection molding is performed in a mold.

Due to the above (a) to (c), stable molding cannot be performed, and continuous operation of the injection molding machine becomes difficult.

The present invention has been made in view of the above problems, and provides a liquid phase injection molding method of metal capable of realizing stable molding operation in the metal injection molding method. This is an issue.

[0007]

According to the present invention, the nozzle mounted on the cylinder head of an injection molding machine is a self-sealing nozzle, and the nozzle is heated to keep the metal in the nozzle in a liquid phase. Solved the problem. With this configuration, the metal melted and kneaded with the screw to form a liquid phase can be injected into the mold cavity without making a solid plug at the nozzle tip, thus ensuring stable molding operation. It becomes possible to do.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described.

The method of injection-molding a metal as a liquid phase by melting a metal in an in-line screw type injection molding machine according to the present invention (a liquid-phase injection molding method for a metal) is such that a nozzle mounted on a cylinder head is a self-sealing nozzle. The nozzle is heated to keep the metal in the nozzle in a liquid phase. The injection molding method is suitable for injection molding of a metal having a melting point of 700 ° C. or lower. The nozzle is preferably a core valve type or rotary type self-sealing nozzle.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

1 to 4 are views showing a core valve type self-sealing nozzle mounted on a cylinder head of an injection molding machine. 1 is a longitudinal sectional view thereof, and FIGS. 2 and 3 are A- of FIG.
FIG. 4 is a sectional view taken along line A, and FIG. 4 is a view taken in the direction of arrow C in FIG.

As shown in FIG. 1, a cylinder head 2 is attached by a bolt 17 to the tip of a cylinder 1 of an injection molding machine. A nozzle 3 having an opening 3a is screwed into the tip of the cylinder head 2.
Inside the cylinder head 2, there are provided a plurality of flow paths 14 that connect the inside of the cylinder 1 into which the screw 15 is inserted and the inside of the nozzle 3. Further, a hole 5a is formed in the vertical direction in the figure on the tip side of the cylinder head 2,
The rotary shaft 5 is fitted in the hole 5a. In addition, a hole 4a that vertically communicates with the hole 5a is formed in the center of the tip of the cylinder head 2, and the needle valve 4 is inserted into the hole 4a so as to be movable back and forth. The tip of the needle valve 4 can be inserted into the opening hole 3 a of the nozzle 3, and the rear end is in contact with the rotary shaft 5. A heater 16 is attached to the outer periphery of the nozzle 3, the cylinder head 2, and the cylinder 1, and the temperature is controlled by a temperature detector 18.

As shown in FIG. 4, the rotary shaft 5 is connected to an actuator 9 via an arm 6, a shaft 7 and a yoke 8. A hinge 12 of the actuator 9 is pivotally attached to a bracket 10 via a shaft 11, and the bracket 10 is fixed to a plate 13 attached to a flange of the cylinder head 2.

Next, the operation of the self-sealing nozzle described above will be described.

In the metal melting / kneading step, the actuator 9 is operated by switching the solenoid valve, and the movement of the piston rod of the accumulator 9 is changed to the rotational movement by using the yoke 8, the shaft 7 and the arm 6, and the arm 6 is moved. About 90 degrees from the state shown in FIG. 2 to the state shown in FIG.
Rotate °. Then, the needle valve 4 that is in contact with the rotating shaft 5 advances, its tip is inserted into the opening hole 3a of the nozzle 3, the opening hole 3a is blocked, and the molten metal is prevented from flowing out from the nozzle 3. It

In the metal injection step, the rotary shaft 5 is rotated to the state shown in FIG. Then, a retreating force acts on the needle valve 4 by the injection pressure received by the molten metal, the opening hole 3a of the nozzle 3 is released as shown in FIG. 2, and the molten metal is injected into the mold.

Further, in any of the above-mentioned steps, the temperature of the nozzle 3 is higher than the melting point of the molten metal, so that the molten metal does not solidify in the nozzle 3.

In the embodiment described above, a core valve type (needle valve type) self-sealing nozzle is used for the nozzle 3, but a rotary self-sealing nozzle shown in FIG. 5 may be used. it can. That is, this embodiment is similar to FIG.
As shown in (a), the rotary shaft 5 is provided with a flow path, and by the rotation of the rotary shaft 5, a nozzle released state shown in FIG. 5 (b) and a nozzle closed state shown in FIG. 5 (c). can do.

According to the above-mentioned embodiment, the metal screw 1
It can be melted and kneaded in 5 and injected into the mold cavity without forming the fixing plug D at the tip of the nozzle.

A typical metal used for injection molding is a magnesium-aluminum alloy as shown in FIG. Usually, a so-called thixomold method is used in which a magnesium alloy containing 9% by weight of aluminum is injection-molded in a molding region of a semi-solidified structure. However, the method according to the present invention has a melting point of 700 ° C. or less and a liquid Suitable for injection molding in the phase molding area. The melting point is 7
When the temperature is higher than 00 ° C, the strength of the needle valve becomes a problem.

[0021]

The liquid phase injection molding method for metals according to the present invention comprises:
Since it is configured as described above, the following effects can be obtained. That is, since injection molding can be performed without forming a solid plug at the tip of the nozzle, the solid phase does not enter into the mold, the flow is smooth, and the molded product is defective, wrinkles, and hot water are unsatisfactory. Defects such as cold are significantly reduced, the quality of molded products is improved, the fluidity is stabilized, the stability of molding conditions is improved, the defective rate is reduced, and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a core valve type self-sealing nozzle used in a liquid phase injection molding method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, showing a closed state of the opening hole of the nozzle.

FIG. 3 is a cross-sectional view taken along the line AA of FIG. 1, showing an open state of an opening hole of a nozzle.

FIG. 4 is a view on arrow C of FIG.

5A and 5B are diagrams showing a rotary type self-sealing nozzle used in a liquid phase injection molding method according to another embodiment of the present invention, wherein FIG. 5A is a longitudinal sectional view and FIG. B- in FIG.
It is a B line sectional view, a figure which shows an open state, Drawing (C) is a BB line sectional view of Drawing (a), and a figure showing a closed state.

FIG. 6 is a typical metal material M used in the present invention.
It is an equilibrium state diagram of a g-Al system alloy.

FIG. 7 is a diagram showing a molten state of the metal material at the tip of the nozzle.

[Explanation of symbols]

 1 Cylinder 2 Cylinder Head 3 Nozzle 3a Opening Hole 4 Needle Valve 4a, 5a Hole 5 Rotating Shaft 6 Arm 9 Actuator 14 Flow Path 15 Screw 16 Heater 17 Bolt 18 Temperature Detector

Claims (4)

[Claims] 1. In a method of melting metal with an in-line screw type injection molding machine to perform injection molding as a liquid phase, a nozzle (3) mounted on a cylinder head (2) is a self-sealing type nozzle, and the nozzle (3) ) Is heated to keep the metal in the nozzle in the liquid phase, the liquid phase injection molding method for the metal. 2. The liquid phase injection molding method for a metal according to claim 1, wherein the melting point of the metal is 700 ° C. or lower. 3. The metal liquid phase injection molding method according to claim 1, wherein the nozzle (3) is a core valve type self-sealing nozzle. 4. The nozzle according to claim 1, wherein the nozzle (3) is a rotary self-sealing nozzle.
Liquid phase injection molding method of the described metal.