JPH1157967A - Method for injection-forming metallic material and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high quality metal injection formed product in a low cost with a simple device by adjusting molten metal to semi-molten state while cooling, pressurizing, supplying the molten metal into a cylinder for injection from a cylinder for supplying the material and injecting the semi-molten state metallic material weighed in the cylinder for injection into a die. SOLUTION: The molten metal in a molten metal supplying hopper 1 is supplied into the cylinder 2 for supplying the material from a material supplying hole 12. This supplied molten metal is pressurized with a pressurizing plunger 3 and passed through a flowing passage 5 arranged at a cooling element 4 and successively, supplied into the cylinder 7 for injection through a connecting passage 6. The semi-molten metal material is supplied into the cylinder 7 for injection and at the same time, a plunger 8 for injection is retreated and the semi-molten metal material is stored into the cylinder 7 for injection. At the time point of supplying a prescribed quantity of the semi- molten metal material, a stop valve 11 arranged to a nozzle 10 is opened, and successively, the plunger 8 for injection is advanced at high speed and the semi-molten metal material is injected into the die arranged at the tip part of the nozzle 10 to cast the metal product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for injection molding a metal material in a molten or semi-molten state. More specifically, the present invention relates to a method and an apparatus for injection molding a metal material without performing mechanical stirring or electromagnetic stirring.

[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, while supplying the metal pellets into the injection cylinder of the injection molding apparatus and heating the temperature of the metal material in the injection cylinder in an inert atmosphere between the solidus temperature and the liquidus temperature, mechanical stirring or A method in which a screw is rotated by means of electromagnetic stirring or the like to apply a shearing force and gradually fed as a semi-solid slurry to the front of the injection cylinder to perform injection molding (for example, Japanese Patent Application Laid-Open No. 3-504830, Japanese Patent Application Laid-Open No. 155918). These methods suppress the dendritic crystal of metal (so-called dendrite) by applying a shear force to a metal material in a coexisting state of a solid phase and a liquid phase, and coexist in a coexisting state of fine particles and a liquid, that is, thixotropic. Injection molding is performed in the form of a slurry to obtain a homogeneous metal molded body.

In the conventional method of injection-molding a metal material in a semi-molten state, the metal material in a solid state is supplied to a screw in an injection molding apparatus. There is a problem that a cylinder or a screw is liable to be worn or damaged during high-speed rotation or forward / backward travel. In metal injection molding, especially at a speed 10 times faster than resin molding (1 to 10 m / s)
This problem is serious because it requires injection at In addition, in the case of performing electromagnetic stirring, there is a disadvantage that the apparatus is expensive to perform strong stirring.

On the other hand, Japanese Patent Application Laid-Open No. 5-285626 discloses a structure in which a plunger injection machine is added to a kneading injection machine for producing a semi-molten metal material in order to avoid an adverse effect on a screw during high-pressure injection of a metal material. It has a pre-plastic type structure in a so-called resin material injection molding machine.

[0006]

However, the metal material injection molding apparatus disclosed in Japanese Patent Application Laid-Open No. 5-285626 still uses a screw-type injection molding machine for semi-melting the metal material. It has been difficult to avoid wear and breakage of cylinders and screws of the device.
In addition, in this method, since the metal material to be injected into the injection molding machine is a solid, there is a problem that a device for performing a semi-solidification becomes large, and the state is controlled by converting the solid into a semi-molten state. It was difficult to do.

Therefore, the present invention provides a metal material injection molding apparatus which can easily adjust a metal material to a semi-molten state.
An object of the present invention is to provide a metal material injection molding method and apparatus capable of supplying a low-cost, high-quality metal injection molded product with a simple apparatus.

[0008]

In order to solve the above-mentioned problems, an injection molding method for a metal material according to the present invention comprises a metal material in a semi-molten state while cooling a molten metal introduced into a material supply cylinder. It is characterized in that the material is pressurized and supplied from the material supply cylinder to the injection cylinder, and the semi-molten metal material measured in the injection cylinder is injected into the mold.

In the above metal material injection molding method, the method of preparing a metal material in a semi-molten state in a material supply cylinder includes a cooling element disposed in the material supply cylinder and a wall of the material supply cylinder. A flow path composed of gaps is provided, the cross-sectional area of the flow path is changed continuously or discontinuously, and a molten metal is passed through the flow path to prepare a metal material in a semi-molten state. be able to.

In the above-described method for injection molding a metal material, solidification of the material in the flow path can be prevented by causing a part of the molding material to flow back to the supply side at the time of injection.

Further, the metal material injection molding apparatus of the present invention has a material supply cylinder for preparing a molten metal material in a semi-molten state and an injection cylinder for injecting the metal material in a semi-molten state. The material supply cylinder has a molten metal supply hopper for introducing molten metal into the material supply cylinder, and has a cooling element therein, between the material supply cylinder and the cooling element. A pressurizing device that forms a passage for allowing the metal material in a molten or semi-molten state to pass therethrough, and that can apply pressure to the molten metal supplied inside the material supply cylinder, and is adjusted to a semi-molten state. And an injection nozzle for introducing the metal material into the injection cylinder, wherein the injection cylinder has a plunger capable of injecting the metal material in a semi-molten state.

In the above metal material injection molding apparatus, it is preferable that the molten metal supply hopper has a heating device capable of maintaining the state of the molten metal.

The metal material can be easily adjusted to a semi-molten state by the operation of each of the following processes by using the simple metal material injection molding apparatus of the present invention having the above characteristics, and the incorporation of bubbles is prevented. A homogeneous metallic injection molded product is obtained.

That is, the molten metal material (molten metal) supplied to the material supply cylinder is pressurized by a suitable pressurizing means such as a plunger and sent to a communicating injection cylinder. At this time, the molten metal passes through a narrow flow path provided between the cooling element maintained at a temperature below the liquidus temperature and above the solidus temperature and the material supply cylinder. At this time, the cylinder wall surface is maintained at a temperature below the liquidus temperature and above the solidus temperature,
Take away heat from molten metal. A large number of crystal nuclei are generated from the cooled molten metal, and are sent to an injection cylinder in a semi-molten state. The flow path provided in the cooling element should not only have a constant cross-sectional area, but also a shape that changes the cross-sectional area continuously or discontinuously to change the flow velocity or cause convection. Is also effective.

When the metal material in a semi-molten state is sent to an injection cylinder maintained at a temperature at which a desired solid fraction can be obtained below the liquidus temperature and above the solidus temperature, the pressure causes the injection plunger. When the retreat is performed and a predetermined amount of the semi-molten metal material is stored, the injection plunger is advanced at a high speed to inject the semi-molten metal material into the mold. By retracting the injection plunger with the pressure of the supplied semi-molten metal material as described above, entrainment of air or atmospheric gas can be prevented. It is also possible to detect the pressure of the supply material and forcibly retract it while applying feedback so that the pressure becomes constant.

In order to prevent the material from completely solidifying in the flow path of the cooling element during the injection step and the pressure-holding step and to block the flow path, a certain amount of semi-molten metal material is supplied to the molten metal supply side. It is desirable to have a backflow so that no material remains in the cooling element at all times. It is also effective to form the surface of the cooling element with a material having poor wettability with the molding material.

[0017]

FIG. 1 shows an example of a metal material injection molding apparatus according to the present invention, and a mold apparatus is not shown.

In the injection molding apparatus for a metal material shown in FIG.
Reference numeral 1 denotes a molten metal supply hopper for storing and supplying molten metal, and may be provided with a heating device for melting the forming metal material. Reference numeral 2 denotes a material supply cylinder for preparing the molten metal supplied from the molten metal supply hopper 1 into a semi-molten metal material and supplying the molten metal to the injection cylinder 7.

In the material supply cylinder 2, a cooling element 4 and a heating device (not shown) for setting the temperature of the supplied molten metal below the liquidus temperature to above the solidus temperature are arranged. Temperature control is possible. A continuous depression is formed in the cooling element 4 from the upstream side to the downstream side of the molten metal, and a metal material in a molten or semi-molten state is passed between the material supply cylinder 2 and the cooling element 4. Are formed. A communication path 6 leading to an injection cylinder 7 is provided at a tip of the material supply cylinder 2.
Is provided. A pressure plunger 3 for applying pressure to the molten or semi-molten metal material in the material supply cylinder 2 is arranged.

In the injection cylinder 7, an injection plunger 8 for injecting the semi-molten metal material measured therein is used.
Is arranged. At the front of the injection cylinder 7, a variable space measuring chamber 9 for receiving the semi-molten metal material supplied from the material supply cylinder 2 and measuring a required amount is formed. When the injection plunger 8 is retracted, the volume of the measuring chamber 9 increases. A nozzle 10 for injecting the semi-molten metal material toward a mold (not shown) is provided at the tip of the injection cylinder 7. A stop valve 11 is provided in the nozzle 10 to prevent the semi-molten metal material from leaking from the nozzle 10 when the semi-molten metal material is supplied into the injection cylinder 7. Note that it is also possible to prevent leakage by pressing the nozzle 10 against another appropriate member without providing the stop valve 11 on the nozzle 10.

A magnesium alloy (ASTM: AZ91) is used as a metal material by the metal material injection molding apparatus shown in FIG.
An embodiment of the present invention will be described by taking, as an example, injection molding using D).

The metal material is melted in a molten metal supply hopper 1 provided with a heating means, or is melted by a separately provided melting furnace and supplied to the molten metal supply hopper 1. The molten metal in the molten metal supply hopper 1 is supplied from the material supply port 12 of the material supply cylinder 2 into the material supply cylinder 2. The supplied molten metal is pressurized by the pressurizing plunger 3, passes through the flow path 5 provided in the cooling element 4, and then passes through the communication path 6.
Through the cylinder 7 for injection. At this time, a medium for temperature adjustment is passed through the cooling element 4 so as to maintain a constant temperature. Similarly, the material supply cylinder 2 also has a heating means and a cooling means and is controlled at a constant temperature. The set temperature is lower than the liquidus temperature of the metal material or higher than the solidus temperature, and is a temperature at which a desired solid phase ratio is obtained. The molten metal is cooled while passing through the flow path 5 between the cooling element 4 and the material supply cylinder 2, and a large number of crystal nuclei are generated. However, the molten metal in which many crystal nuclei have been generated is flowing at high speed, so that dendrites of metal, so-called dendrites, do not grow, and a homogeneous semi-molten mixture of many primary crystals and liquid phase The state is supplied to the injection cylinder 7.

At the same time that the semi-molten metal material is supplied to the injection cylinder 7, the injection plunger 8 is retracted, and the semi-molten metal material is stored in the injection cylinder 7. At this time, it is preferable that the injection plunger 8 is controlled so that the pressure of the supplied semi-molten metal material is kept constant so that air and atmospheric gas are not entrained. When a predetermined amount of the semi-molten metal material is supplied, the stop valve 1 provided on the nozzle 10
Then, the injection plunger 8 is advanced at a high speed, and the semi-molten metal material is injected into a mold (not shown) provided at the tip of the nozzle 10 to cast a metal product. In order to prevent dendrite from growing in the cooling element 4 and fixing the material during the injection molding process in which the mold cavity is filled with the magnesium alloy and the pressure holding process for preventing solidification shrinkage during cooling. Then, the pressurizing plunger 3 is gradually retracted, and the semi-molten metal material is returned into the material supply cylinder 2 so that the semi-molten metal material always flows backward little by little.

After the solidification of the material in the mold is completed, the magnesium alloy product in the mold is further cooled and waited for cooling to a temperature having sufficient strength, and the mold is opened and taken out. After the material in the mold is solidified, the stop valve 11 is closed, the pressure plunger 3 is retracted to the rear of the material supply port 12 to prepare the material for the next molding, and the molten metal is supplied to the material supply cylinder. 2 into the injection cylinder 7 as described above.
To supply a semi-molten metal material.

[0025]

According to the present invention, a molten metal is supplied to a material supply cylinder, and a semi-molten metal material is prepared while being cooled. A shear force is applied to the solid metal material to bring it into a semi-molten state. There is no need to perform mechanical stirring for stirring or electromagnetic stirring for stirring the molten metal. Therefore, the injection molding apparatus for metal materials can be simplified, the wear of the apparatus members is small, the power consumption is low, the solid metal material such as metal material pellets is not used, and inexpensive ingot material can be used, so that the running cost is also low. It can be kept low.

[Brief description of the drawings]

FIG. 1 shows an example of a metal material injection molding apparatus of the present invention, in which a mold apparatus is not shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten supply hopper 2 Material supply cylinder 3 Pressurizing plunger 4 Cooling element 5 Flow path 6 Communication path 7 Injection cylinder 8 Injection plunger 9 Measuring chamber 10 Nozzle 11 Stop valve 12 Material supply port

Claims (5)

[Claims] (1) A molten metal introduced into a material supply cylinder is prepared into a semi-molten metal material while being cooled, and is supplied under pressure from the material supply cylinder to an injection cylinder. 2) A metal material injection molding method characterized by injecting a semi-molten metal material measured in an injection cylinder into a mold. 2. A method for preparing a metal material in a semi-molten state, comprising: a cross-sectional area of a flow path formed by a gap between a cooling element disposed in a material supply cylinder and a wall surface of the material supply cylinder. 2. The injection molding method of a metal material according to claim 1, wherein the temperature is adjusted continuously or discontinuously, and the molten metal is passed through the flow path. 3. A method of injecting a metal material into a mold, wherein a part of the molding material is caused to flow back to a supply side at the time of injection to prevent solidification of the material in the flow path. Item 1. An injection molding method of a metal material according to Item 1. 4. An injection molding apparatus for a metal material, comprising: a material supply cylinder for maintaining a molten metal material in a semi-molten state; and an injection cylinder for injecting the semi-molten metal material. The supply cylinder has a molten metal supply hopper for introducing molten metal into the material supply cylinder, has a cooling element therein, and has a molten or half molten material between the material supply cylinder and the cooling element. It has a passage for allowing the molten metal material to pass therethrough, has a pressurizing means capable of applying pressure to the molten metal supplied inside the material supply cylinder, and adjusts the metal material adjusted to a semi-molten state. Injection of a metal material, comprising an introduction nozzle for introducing the metal material into an injection cylinder, wherein the injection cylinder has a plunger capable of injecting a metal material in a semi-molten state. Form apparatus. 5. The metal material injection molding apparatus according to claim 4, wherein the molten metal supply hopper has a heating device capable of maintaining a state of the molten metal.