JPH1157971A - Metallic material injection molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic material injection molding device capable of preventing wear and breaking of a cylinder screw device and obtaining a homogeneous metal injection formed part. SOLUTION: The metallic material injection molding device is arranged so that a screw extrusion device 2 to turn a solid metallic material to a molten state or a partially molten state is communicated to an injection cylinder screw.device 1 for metallic material injection. A position to communicate the screw extrusion device to the cylinder.screw device 1 for metallic material injection is arranged to a rear part of the cylinder.screw device 1 for injection so as to make imparting of shear force by an injection screw to the metallic material possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus for a metal material in a molten or semi-molten state. For more information,
The present invention relates to a metal material injection molding apparatus capable of preventing wear and breakage of an injection cylinder / screw device and obtaining a homogeneous metal injection molded body.

[0002]

2. Description of the Related Art Heretofore, there has been known a die casting method in which a molten metal is injected into a mold under pressure. In the die-casting method, since the metal is melted and injected into the mold at a high pressure in a low-viscosity state, it is unavoidable that air is involved during molding and air bubbles are mixed in the metal molded body, or However, there are problems such as the need for post-processing, the increase in scrap material, and the necessity of raising the temperature and pressure of the metal forming material.

As a metal forming technique for solving such problems of the die casting method, an attempt has been made to injection-mold a metal material in a semi-molten state at a lower temperature than the die casting method. That is, the metal pellet is supplied into the injection cylinder of the injection molding apparatus, and the screw is rotated while heating the temperature of the metal material in the injection cylinder in an inert atmosphere between the solidus temperature and the liquidus temperature. (See, for example, JP-A-3-504830 and JP-A-7-155918). These methods suppress the growth of metal dendrites (so-called dendrites) by applying a shearing force to a metal material in a coexisting state of a solid phase and a liquid phase. Injection molding is performed in the form of a thixotropic slurry to obtain a homogeneous metal molded body.

[0004]

In the conventional method of injection molding a metal material in a semi-molten state, the solid state metal material is supplied to a screw in an injection molding apparatus. However, when the screw is rotated at high speed or moved forward and backward in the cylinder, there is a problem that the cylinder and the screw are likely to be worn or damaged. This problem is serious in the case of injection molding of a metal material, since it is necessary to inject at a speed (1 to 10 m / s) at least ten times as fast as that of resin molding. Accordingly, it is an object of the present invention to provide a metal material injection molding apparatus capable of preventing a cylinder screw device of an injection molding apparatus from being worn or damaged and obtaining a homogeneous metal injection molded body.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an injection molding apparatus for a metal material according to the present invention is a metal material injection molding apparatus for molding a solid metal material into a molten or semi-molten state by injection molding. In the molding apparatus, a screw extruder capable of bringing a solid metal material into a molten or semi-molten state is provided in communication with a cylinder / screw device for injection of a metal material. The position where the screw extruder is communicated with the metal material injection cylinder / screw device is disposed at the rear of the injection cylinder / screw device so that a shear force can be applied to the metal material by the injection screw. I do. Further, by disposing the material at the rear, the material does not flow backward to the screw extruder at the time of injection, and a check mechanism is not required.

The screw extruder is provided with a heating device for guiding the metal material to a molten or semi-molten state. Since the screw extruder sets the metal material in a molten or semi-molten state by a shearing action of the screw and heating by a heating device provided in the extruder, the screw of the screw extruder only needs to rotate. The screw extrusion device, in order to efficiently impart a shearing action,
A twin-screw or triple-screw extruder may be used.

In the injection molding apparatus for a metal material of the present invention, since the molten or semi-molten state is achieved in the screw extruder, a cylinder / screw device for injection molding to which the molten or semi-molten metal material is supplied. Can be prevented from being worn or damaged. Further, in the injection cylinder / screw device to which the molten or semi-molten metal material is supplied, the molten or semi-molten metal material is further subjected to a shearing force due to the rotation of the screw to destroy the grown dendrites, Since metal nucleation continues in parallel, the metal material that finally reaches the tip of the injection cylinder and reaches the required amount is suitable for injection molding in a uniform semi-molten state with suppressed dendrite growth. Metal material. At this point, while stopping the rotation of the injection screw,
A homogeneous metal injection molded body can be obtained by advancing the injection screw at high speed and injection molding a semi-molten or molten metal material into a mold arranged in front of the injection cylinder.

As described above, in the injection molding apparatus for a metal material according to the present invention, the screw extruder for bringing the metal material into a molten or semi-molten state is provided separately from the injection cylinder, so that the injection needs to move forward and backward at a high speed. Since no solid metal material enters the cylinder, good operation and durability are ensured.

Further, in the metal material injection molding apparatus of the present invention, since the rotation speeds of the extrusion screw and the injection screw can be set separately, the extrusion screw to which the solid metal is supplied has a low rotation speed and the injection screw has a low rotation speed. The degree of freedom in setting the screw is increased, for example, by increasing the number of revolutions to suppress the growth of dendrite.

As the extruding screw, besides a normal single screw, it is possible to employ a twin screw or a triaxial or higher screw having a high kneading and mixing ability. The uniformity of the injection molded article is improved. In this case, since the kneading ability is high, it is possible to cope with the molding of the particle-dispersed composite material or the fiber-dispersed composite material.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a metal material injection molding apparatus according to the present invention, and is a cross-sectional view of a portion excluding a molding die, in which an extrusion apparatus is arranged perpendicular to an injection cylinder.
FIG. 2 shows another example of the metal material injection molding apparatus of the present invention, in which an extruding apparatus is arranged in parallel with an injection cylinder.
It is sectional drawing of the part except the shaping | molding die. The extruder can be installed in an oblique direction depending on the installation space or the like.

In FIGS. 1 and 2, reference numeral 1 denotes an injection cylinder / screw device, which has a helical blade therein, can reciprocate, and can rotate to transfer a metal material forward. The injection screw 4 is inserted into the injection cylinder 3 and slides in the injection cylinder 3. The injection cylinder 3 is configured to be heated and cooled by a temperature control device (not shown). The tip of the injection cylinder / screw device 1
A nozzle 5 for introducing a molten or semi-molten metal material into a mold is provided. The mold device including the mold may be a normal mold device, and is not shown. At the rear of the injection cylinder and screw device 1, the injection screw 4 is connected to the rear of the injection screw 4 to rotate the injection screw 4, and the injection screw 4 is moved forward and backward. Screw horizontal driving device 7 is provided.

Reference numeral 2 denotes a screw extruder, which has an extruding screw 9 for performing only rotation operation and an extruding cylinder 8 for accommodating the extruding screw 9 therein. The extrusion cylinder 8 is configured to be heated by a heating device (not shown). The position where the screw extruder 2 communicates with the metal material injection cylinder / screw device 1 is located at the rear of the injection cylinder / screw device 1 so that a shear force can be applied to the metal material by the injection screw 4. Are located. In FIG. 1, the screw extruding device 2 is provided vertically, and in FIG. 2, the screw extruding device 2 is arranged in parallel with the injection cylinder / screw device 1. At the upper end (FIG. 1) or the rear end (FIG. 2) of the screw extrusion device 2, an extrusion screw rotation drive device 11 for rotating and driving the extrusion screw 9 is provided. At the rear (FIG. 1) or at the rear (FIG. 2), there is provided a hopper 10 for containing the metal material and introducing the metal material into the screw extruder 2.

1 and 2, a magnesium alloy (AST) is used as the metal material.
M: AZ91D), using injection molding as an example,
An embodiment of the present invention will be described.

As the metal material, a granular magnesium alloy material having a size of about 2 mm to 5 mm is used. Examples of the granular magnesium alloy material include materials obtained by various manufacturing methods such as mechanically crushed materials and materials manufactured by a method such as an inert gas atomizing method.

The hopper 10 is desirably heated, and is supplied with an inert gas such as argon gas so that air and moisture contained in the magnesium alloy material can be removed.
It is desirable to supply to. The heating temperature of the hopper 10 is
The temperature is set to a temperature at which water can be sufficiently removed (for example, 150 ° C.) and a temperature at which a liquid phase of the magnesium alloy is generated (425 ° C. in the case of AZ91D). The granular magnesium alloy supplied from the hopper 10 is heated by a heating device provided in the extrusion cylinder 8 and is subjected to shear by the rotating extrusion screw 9 to be in a semi-molten state, discharged from the tip of the extrusion cylinder 8 and injected. It is supplied into the cylinder 3.

The metal material is supplied from the hopper 10 to the extrusion cylinder 8.
A temperature gradient is provided from the material supply portion of the extrusion cylinder 8 supplied into the inside toward the tip, so that the metal material gradually increases the liquid phase amount toward the tip. The temperature of the extrusion cylinder 8 is set to, for example, 350 ° C. at the material supply part and 580 ° C. lower than the liquidus temperature at the tip part. The set temperature is determined from the material and the desired solid fraction.

The magnesium alloy in a solid-liquid mixed state supplied from the extrusion cylinder 8 to the injection cylinder 3 is further subjected to shearing by the injection screw 4 and is temperature-controlled by heating or cooling so as to have a desired solid fraction. As well as being fed forward. The injection screw 4 rotates and gradually retreats while storing a semi-molten magnesium alloy in front. When the magnesium alloy reaches a preset measurement value, the rotation of the extrusion screw 9 and the injection screw 4 is stopped, and then the injection screw 4 is advanced at a high speed. A magnesium alloy molded body is cast by jetting into a mold.

Until the mold cavity is filled with magnesium alloy and solidification is completed, the extrusion screw 9 continues to apply pressure to the molten or semi-molten magnesium alloy to prevent sinking and other defects of the product due to solidification shrinkage. I do. When the coagulation is completed, the extrusion screw 9 and the injection screw 4 start rotating, and supply of the material is started in preparation for the next injection. The magnesium alloy product in the mold is further cooled and waited for cooling to a temperature having sufficient strength, and then the mold is opened and removed.

[0020]

According to the present invention, in a screw extruder provided in a cylinder / screw device of an injection molding device, heating and shearing force are applied to a solid metal material to prepare a molten or semi-molten state. The metal material introduced into the cylinder screw device of the injection molding device is further subjected to a shearing force by a screw, and the metal material measured in front of the injection cylinder is in a uniform molten or semi-molten state. Therefore, by injecting this metal material into the mold from the cylinder and screw device, a homogeneous metal injection molded product can be obtained.

[Brief description of the drawings]

FIG. 1 shows an example of an injection molding device for a metal material of the present invention, in which an extrusion device is arranged perpendicular to an injection cylinder.
It is sectional drawing of the part except the shaping | molding die.

FIG. 2 is a sectional view of another example of the metal material injection molding apparatus according to the present invention, in which an extruding apparatus is arranged in parallel with an injection cylinder, excluding a molding die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection cylinder and screw device 2 Screw extrusion device 3 Injection cylinder 4 Injection screw 5 Nozzle 6 Injection screw rotation drive device 7 Injection screw horizontal drive device 8 Extrusion cylinder 9 Extrusion screw 10 Hopper 11 Extrusion screw rotation drive device

Claims (2)

[Claims] 1. A metal material injection molding apparatus for injection molding a solid metal material into a mold in a molten or semi-molten state,
An injection molding apparatus for a metal material, wherein a screw extruder capable of bringing a solid metal material into a molten or semi-molten state is provided in communication with an injection cylinder / screw device. 2. The position where the screw extruder communicates with the metal material injection cylinder / screw device is located at the rear of the injection cylinder / screw device where a shear force can be applied to the metal material by the injection screw. The injection molding apparatus for a metal material according to claim 1, wherein