JP2002066695A - Method and apparatus for producing pellets for thixomolding injection molding machine - Google Patents

Abstract

(57) [Summary] To manufacture a raw material for a thixomolding injection molding machine, to establish a technique capable of manufacturing pellets having a fixed shape and size with high accuracy and high efficiency. SOLUTION: A molten metal M of a low melting point metal melted in a melting device 10 is sucked into a cylinder 31 of a pellet manufacturing device 30 and is semi-solidified from the inside of the cylinder 31 by an operation of a rod 33 which advances and retreats from an opening of the cylinder 31. Is extruded and cut into fixed lengths to produce pellets. This pellet manufacturing apparatus 30 is installed at the previous stage of the thixomolding injection molding machine 40, and the produced pellets are put into the raw material hopper 43 of the injection molding machine 40, so that the pellet manufacturing and injection molding lines can be made continuous. Can be.

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 producing pellets used as a raw material in injection molding of a low melting point alloy, particularly in thixomolding injection molding.

[0002]

2. Description of the Related Art Magnesium and magnesium alloys (hereinafter referred to as magnesium alloys) have recently attracted attention as low melting point alloys. Magnesium alloy is
Since it is the lightest among structural metals that have been put into practical use, has high specific strength (proof strength / specific gravity), and has excellent characteristics as a structural body in terms of dimensional stability, vibration absorption, etc., automobiles It is widely used in aviation, space equipment, home appliances, leisure and sports equipment, and other machinery parts.

[0003] The method of forming a magnesium alloy is roughly divided into
There are a die casting method in which a molten metal completely melted in a melting furnace is cast into a mold at a high pressure, and a thixomolding method in which a melting step is omitted and a raw material is supplied in a semi-solid state. In the thixomolding method, a raw material in the form of pellets or chips of a magnesium alloy is put into a hopper, and the pellets or chips are heated at a temperature above the freezing point and below the melting point in a cylinder by a heater, and a semi-solid state in which a liquid phase and a solid phase coexist. And injecting it into a mold.

The thixomolding method has many advantages over the die casting method. In particular, the factory does not require a melting furnace or extensive fire prevention measures, does not require melting technology and experience, reduces energy costs, and has a thin wall. It is excellent in that a molded article is formed, bubbles are hardly formed in the molded article, the molding cycle time is short, and scrap can be recycled.

[0005] Regarding the recycling of magnesium alloy scrap, there are two methods of producing pellets or chips for the raw material of the thixomolding injection molding method: a method of cutting and crushing waste materials (including return materials, the same applies hereinafter) into chips. There is a method of melting and extruding waste materials to form pellets or chips.

As a method of cutting and crushing, for example, there is a method described in JP-A-2000-33279.
In this method, waste material is cut and crushed to form primary crushed material, and the primary crushed material is cut and cut by a fixed blade and a rotary blade, and is passed through a screen to obtain chips.

[0007] As a method by melting and extrusion, for example, JP-A-11-123373, JP-A-11-113
There is a method described in Japanese Patent No. 23502. JP-A-11-1
The method described in Japanese Patent No. 23373 is a method in which a waste material is heated while being pressed so as to be in a molten or semi-solidified softened state, extruded from a nozzle, formed into a rod-shaped body, and cut. The method described in JP-A-11-123502 is a method in which waste material is heated and kneaded to form a semi-solidified material, extruded from a die and cut into pellets.

[0008]

There are advantages and disadvantages in the method of manufacturing recycled chips for the thixomolding injection molding machine, such as a method of forming chips by cutting and crushing, and a method of forming pellets or chips by melting and extrusion. There is. The method of cutting into chips by cutting and crushing has the advantage of reducing energy and eliminating the need to treat exhaust gas, dross, and sludge as compared to the conventional method that re-melted and refined waste materials to make ingots and re-chips them. On the other hand, there is a problem that impurities are mixed into the alloy itself due to cutting and crushing, and fine powder having high explosiveness is generated. In addition, the method of forming pellets or chips by melting and extruding has the advantage that there is little variation in the shape of the pellets or chips as compared with the method of cutting and crushing, and there is an advantage that fine powder is not generated, but the apparatus becomes larger, There is a problem that it is difficult to control the cooling rate of pellets or chips.

Such a problem is not limited to the magnesium alloy, and is a problem common to the injection molding of the thixomolding method of other low melting point metals such as an aluminum alloy and a zinc alloy.

The problem to be solved by the present invention is to melt and mold waste materials of a low melting point metal such as a magnesium alloy to produce raw materials for a thixomolding injection molding machine. It is to establish a technology that enables efficient and efficient production.

[0011]

SUMMARY OF THE INVENTION The present invention is a method for producing pellets for a thixomolding injection molding machine from molten metal obtained by dissolving waste material of a low melting point metal such as a magnesium alloy. And a semi-solid metal is extruded from the cylinder by the operation of a rod that advances and retreats from the opening of the cylinder, and is cut into a predetermined length to produce pellets.

The above-mentioned method for producing pellets comprises a container for accommodating the molten metal, and a cylinder for extruding the molten metal sucked from the container to form pellets, wherein the cylinder has a molten metal extrusion port at a lower end portion, The present invention can be implemented by using an apparatus having a piston at an upper end and a molten metal inlet at an intermediate portion, and having a rod that moves forward and backward through the piston and the extrusion port.

When this apparatus is used to manufacture pellets for a thixomolding injection molding machine, waste materials generated in the process of manufacturing low-melting-point metals and product wastes are appropriately cut and crushed to melt in a melting furnace. Degassing, if necessary,
After removing impurities and adjusting components, the molten metal is accommodated in a container, and the molten metal is sucked from the container into a cylinder for forming pellets to produce pellets of a low melting point metal.

The above-described pellet forming cylinder has a structure having a molten metal suction port, a push-out port, and a piston, and having a rod that moves forward and backward through the piston and the push-out port. The molten metal is sucked into the cylinder, the piston is advanced, and the rod is advanced and retracted with the suction port closed, so that a certain amount of semi-solid metal is extruded from the extrusion port, cut into a certain length, and pellets are cut. Manufactured.

At this time, by interposing an inert gas such as argon in the space between the molten metal in the cylinder and the piston, the gas is compressed when the piston is advanced, so that the gas is compressed. When the rod advances, the semi-solid metal is extruded from the extrusion port by the internal pressure of the cylinder. The amount of extruded semi-solid metal is determined by the stroke of the piston, ie, the pressure of the enclosed inert gas, and the amount and time of the rod advance and retreat, ie, the stroke of the moving rod, and the size of the pellet can be adjusted accordingly. it can.

Further, as a method of manufacturing pellets for a thixomolding injection molding machine, a method of forming a large number of casting molds corresponding to the size and shape of the pellets while moving a mold having a low melting point metal into the casting molds is carried out. May be employed by injecting a molten metal in which is melted and solidifying it to form pellets.

The above-mentioned method for producing pellets comprises a container for accommodating a molten metal, and a casting apparatus having a mold for forming a number of casting holes corresponding to the dimensions and shape of the pellets and moving in an endless orbit manner. It can be carried out by using the apparatus described above.

When pellets are produced using this apparatus, waste materials of low melting point metal are melted and degassed as necessary.
The molten metal from which impurities have been removed and components have been adjusted is housed in a container, and the molten metal is sequentially poured from the container into a casting mold of a moving mold of a casting apparatus and solidified to produce pellets.

As described above, according to the method and apparatus of the present invention, it is possible to automatically, continuously and efficiently produce pellets for a thixomolding injection molding machine from molten metal in which low-melting metal waste material is dissolved. it can. In particular, if the apparatus of the present invention is installed in the preceding stage of the thixomolding injection molding machine and the produced pellets are put into the raw material hopper of the injection molding machine, the pellet production and injection molding lines can be made continuous. Can be.

[0020]

FIG. 1 is a view showing the entire configuration of a magnesium alloy injection molding facility according to an embodiment of the present invention. The injection molding facility of the present embodiment is a facility that operates under a system for pelletizing and recycling magnesium alloy waste material, and includes a melting device 10, a molten metal container 20, a pellet manufacturing device 30, and an injection molding machine 40. Basic configuration.

The melting device 10 comprises a melting furnace 11, a charging device 12 for continuously charging magnesium alloy waste material into the melting furnace 11, and a supply pipe 13 for supplying molten metal to a molten metal container 20. The dissolving apparatus itself is known. The molten metal is continuously or intermittently supplied to the molten metal container 20 by an electromagnetic pump 14 provided in the supply pipe 13. The molten metal container 20 is the same as a conventionally known container.

The injection molding machine 40 comprises a molding machine main body 41, a mold 42, and a hopper 43 for inputting raw material pellets supplied from the pellet production apparatus 30, and the injection molding machine itself is a known one. The pellets fed into the molding machine main body 41 from the charging hopper 43 are
In the cylinder, the mixture is heated to a temperature higher than the freezing point and lower than the melting point in a cylinder, injected into a mold in a semi-solidified state in which a liquid phase and a solid phase coexist, and formed into a predetermined shape to obtain a product P.
The injection molding machine itself is known.

FIG. 2 is a view showing the structure and operation principle of the pellet manufacturing apparatus, FIG. 3 (a) is a partially cutaway front view showing the structure of the cylinder of the pellet manufacturing apparatus, and FIG. 3 (b) is A in FIG. −
4A is a partially cutaway front view showing the structure of the piston, FIG. 4B is a sectional view taken along line BB of FIG.
(A) is a partially cutaway front view showing the structure of the rod, and (b) is a cross-sectional view taken along line CC of (a).

First, the structure of the pellet producing apparatus 30 will be described. The pellet manufacturing device 30 is a device that includes a cylinder 31, a piston 32, and a rod 33, sucks molten metal into the cylinder 31, and extrudes semi-solid metal from the cylinder 31 to form pellets. Cylinder 3
1 has a molten metal extrusion port 31a at a lower end, a piston 32 at an upper end, and a molten metal suction port 31b at an intermediate part, and a rod 33 is configured to advance and retreat through the piston 32 and the extrusion port 31a. ing.

Extrusion port 31a at the lower end of cylinder 31
The through hole 31 of the rod 33 as shown in FIG.
c, and has the same shape as the outer shape of the lower end of the rod 33. Further, as shown in FIG. 3B, eight holes 31d communicating with the bottom surface of the cylinder 31 and the inner surface of the extrusion port 31a are provided in the extrusion port 31a in the circumferential direction.
The hole 31d is a hole for extruding the semi-solid metal in the cylinder 31 to the extrusion port 31a.

The piston 32 is provided at the upper end of the cylinder 31 so as to be movable up and down by sliding on the inner surface of the cylinder 31. The piston 32 has a through hole 32a for a rod 33 at the center thereof.
The lower end is shaped to form a gas filling space 34 described later.

The rod 33 is provided with a through hole 32 of the piston 32.
a through the through hole 31c at the lower end of the cylinder 31, and is moved up and down by a driving device (not shown) to
This is a rod for cutting the semi-solid metal discharged from the extrusion port 31a at the lower end by shearing. The outer shape of the enlarged portion 33a at the lower end of the rod 33 is the same as the inner shape of the extrusion opening 31a. Further, as shown in FIG. 5, the enlarged portion 33a is provided with eight holes 33b communicating with the upper surface and the lower surface of the enlarged portion 33a in the circumferential direction. The hole 33b is provided in the cylinder 3
This hole is for discharging the semi-solid metal extruded from the hole 31d at the bottom to the extrusion port 31a to the outside after being cut.

Next, the operation principle of the pellet producing apparatus 30 will be described. In FIG. 2, (a) is a suction cycle, (b) is a pressurization cycle, (c) is a molding cycle,
(D) shows a cutting cycle.

The suction cycle is a step following the cutting cycle, in which the molten metal M is sucked into the cylinder 31. As shown in FIG. 2A, when the piston 32 is moved upward while the rod 33 is pushed upward, the internal pressure of the argon gas sealed in the gas filling space 34 in the cylinder 31 is reduced. Due to the reduced pressure, the molten metal M is sucked into the cylinder 31 from the suction port 31b.

The pressurizing cycle is a step of pressurizing the molten metal M in the cylinder 31. As shown in FIG.
When the piston 32 is pushed down, the suction port 31b is closed, the internal pressure of the argon gas in the gas filling space 34 increases, and pressure is applied to the molten metal M in the cylinder 31.

The molding cycle is a step of extruding the molten metal M in the cylinder 31 from the extrusion port 31a. As shown in FIG. 2 (c), when the rod 33 is pushed downward, the molten metal M is pressurized in the cylinder 31. The molten metal M in the state is extruded from the hole 31d on the bottom surface of the cylinder toward the extrusion port 31a. The molten metal M extruded into the extrusion port 31a is in the form of slurry in a solid-liquid coexistence state, and is in a semi-solid state near the exit.

The metal slurry in the semi-solid state extruded through the extrusion port 31a is fed to the expanding portion 33 of the rising rod 33.
It is sheared by the hole 33b of (a) and is discharged out of the device in a cut shape to form a columnar pellet.

The cutting cycle is a step of cutting the semi-solid metal extruded from the extrusion port 31a by the molding cycle and stopping the outflow of the semi-solid metal from the extrusion port 31a, as shown in FIG. , Rod 3
3 is pushed upward, the enlarged portion 33 at the lower end of the rod 33 is raised.
a returns to the inside of the extrusion opening 31a, cuts the semi-solid metal extruded by the hole 31d by the molding cycle, and stops the flow of the semi-solid metal from the hole 31d.

By repeating the above four cycles, pellets of a certain size are formed in the molding cycle. In this molding cycle, the extruded amount of the semi-solid metal is determined by the stroke amount of the piston 32 and the stroke amount and speed of the rod 33, so that the size of the pellet can be adjusted thereby.

The pellet manufacturing apparatus 30 is connected to the injection molding machine 4
The molten metal suction port 31b of the cylinder 31 is connected to the molten metal container 20 via the suction pipe 35, and the molten metal in the molten metal container 20 is sucked through the suction pipe 35. Then, pellets as a raw material of the injection molding machine 40 are manufactured. In this manner, pellets for a thixomolding injection molding machine can be automatically, continuously and efficiently produced from a molten metal obtained by dissolving a waste material of a low melting point metal such as a magnesium alloy.

FIG. 6 is a schematic view showing a configuration of a casting apparatus as another embodiment of the pellet producing apparatus. FIG. 7 is a perspective view of members constituting the mold, and FIG. 8 shows a positional relationship between the injection apparatus and the mold. It is a partial perspective view shown.

The pellet producing apparatus 50 comprises an endless orbital moving mold 51, a molten metal pouring device 53, a shielding device 55 and the like, and is a device for producing pellets by casting molten metal.

The moving mold 51 includes a mold member 52 having a T-shaped cross section.
Are connected to form a mold that can move in an endless orbit manner. The mold member 52 is made of an alloyed tool steel whose surface is nitrided, and as shown in FIG. 7, an upper member 52b, a column member 52c, and connecting members 52d, 5 forming a casting mold 52a.
2e. When the mold member 52 is in a horizontal state, the notch portions 52a-1, 52a-2 having a semicircular cross section formed at the rear end and the front end of the upper member 52b of the adjacent mold member 52.
Are brought together to form a casting mold 52a having a circular cross section. The casting mold 52a has an inner diameter of 1 mm and a depth of 1 mm. After the molten metal is injected into the casting mold 52a, it solidifies to form a rod-shaped pellet having an outer shape of 1 mm and a length of 1 mm. The connecting members 52d and 52e are provided with connecting holes 52f and 52g, respectively, and a connecting rod (not shown) is inserted into these holes to connect the adjacent mold members 52.

As shown in FIG. 8, the movable molds 51 are arranged in three rows in the mold moving direction, and these three rows of many connected mold members 52 are hung on drive gears 54 as shown in FIG. It is configured to be rotated and intermittently movable. The periphery of the movable mold 51 is shielded from the outside air by a shielding device 55, and argon gas is blown in from outside through pipes 56 and 57 to cool the periphery and deactivate the atmosphere.

The injection device 53 has three injection nozzles 53b (only one is shown in the figure) at the bottom of a tundish 53a in which a refractory material is lined with a steel outer wall material, and an injection control device (not shown). Is attached. A molten metal supplied from a molten metal container (not shown) is received by a tundish 53a, and a certain amount of molten metal is injected from an injection nozzle 53b into a casting mold 52a formed in a mold member 52 by an injection control device.

The pellets are manufactured by the casting apparatus having the above-described structure as follows. Molten metal is sequentially injected from the injection nozzle 53b of the tundish 53a into the casting die 52a, and the mold member 52 is sequentially moved at a certain time interval corresponding to the injection time by a certain distance corresponding to the interval of the casting die 52a. . The molten metal injected into the casting mold 52a is solidified and cooled during the movement, and as shown in FIG. 6, when the mold member 52 reaches the reversal point, the mold members 52 before and after the contact are separated. Since the metal is divided, the metal solidified by the casting mold 52a drops from the casting mold 52a at the reversal point, and falls into the hopper 58 to be stored.

The pellet manufacturing apparatus 50 is installed above the injection molding machine 40 so that the hopper 58 is located above the input hopper 43 (see FIG. 1) of the injection molding machine 40, and the molten metal container 20 shown in FIG. Is supplied to the tundish 53a through a supply pipe (not shown),
The pellets used as the raw material of No. 0 are produced.

As described above, pellets for a thixomolding injection molding machine can be produced automatically, continuously and efficiently from a molten metal obtained by dissolving a waste material of a low melting point metal such as a magnesium alloy.

[0044]

According to the present invention, a molten metal obtained by melting a waste material of a low melting point metal such as a magnesium alloy is sucked into a cylinder, and a semi-solid metal is extruded from the cylinder by a rod moving forward and backward from an opening of the cylinder to form a pellet. The method of manufacturing, or while moving the mold in which a large number of casting molds corresponding to the dimensions and shapes of the pellets are formed, injecting the molten metal in which the waste material of the low melting point metal is melted into the casting molds and solidifying the pellets. By producing pellets for the thixomolding injection molding machine by the above method, pellets having a constant shape and size can be produced automatically, continuously and efficiently. In addition, the pellet manufacturing apparatus of the present invention is installed in the preceding stage of the thixomolding injection molding machine,
If the produced pellets are put into a raw material hopper of an injection molding machine, a line for pellet production and injection molding can be made continuous.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a magnesium alloy injection molding facility according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure and an operation principle of a pellet manufacturing apparatus.

FIG. 3A is a partially cutaway front view showing a structure of a cylinder of the pellet manufacturing apparatus, and FIG. 3B is a sectional view taken along line AA of FIG.

4A is a partially cutaway front view showing a structure of a piston, and FIG. 4B is a cross-sectional view taken along line BB of FIG.

5A is a partially cutaway front view showing the structure of a rod, and FIG. 5B is a cross-sectional view taken along line CC of FIG.

FIG. 6 is a schematic view showing a configuration of a casting apparatus which is another embodiment of the pellet manufacturing apparatus.

FIG. 7 is a perspective view of members constituting a mold.

FIG. 8 is a partial perspective view showing an arrangement relationship between an injection device and a mold.

[Explanation of symbols]

 Reference Signs List 10 melting device 11 melting furnace 12 charging device 13 supply pipe 14 electromagnetic pump 20 molten metal container 30 pellet manufacturing device 31 cylinder 31a extrusion port 31b suction port 31c through hole 31d hole 32 piston 32a through hole 33 rod 33a enlarged portion 33b hole 34 Gas filling space 35 Suction tube 40 Injection molding machine 41 Molding machine main body 42 Mold 43 Input hopper 50 Pellet manufacturing device 51 Moving mold 52 Mold member 52a Casting mold 52a-1, 52a-2 Notch 52b Upper member 52c Column member 52d, 52e Connecting member 52f, 52g Connecting hole 53 Injection device 53a Tundish 53b Injection nozzle 54 Drive gear 55 Shielding device 56, 57 Piping 58 Hopper M Molten metal P Product

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takamasa Takahashi 3-11-38 Higashicho, Kumamoto City, Kumamoto Prefecture Inside the Industrial Technology Center of Kumamoto Prefecture (72) Inventor Yoshio Moriyama 6-18-1 Suizenji, Kumamoto City, Kumamoto Prefecture Kumamoto Prefecture Enterprise Within the Bureau (72) Inventor Junichi Hirasawa, 1683 Shimosakashita, Oaza, Minamiseki-cho, Tamana-gun, Kumamoto Prefecture Inside (4) Nexus Inc. F-term (reference) 4D004 AA21 AC04 BA05 CA14 CA15 CA29 CB16

Claims (4)

[Claims] Claims 1. A method for producing pellets for a thixomolding injection molding machine from a molten metal in which waste material of a low melting point metal is dissolved, wherein the molten metal is sucked into a cylinder,
A method for producing pellets for a thixomolding injection molding machine, characterized in that a semi-solid metal is extruded from the cylinder by the operation of a rod that advances and retreats from the opening of the cylinder, and is cut into a fixed length to produce pellets. . 2. An apparatus for producing pellets for a thixomolding injection molding machine from molten metal obtained by melting waste material of a low-melting metal, comprising: a container for accommodating the molten metal; and a molten metal sucked from the container. A cylinder for forming a pellet at a lower end portion, a piston at a lower end portion, a piston at an upper end portion, and a suction port for molten metal at an intermediate portion, respectively, and advance and retreat through the piston and the extrusion port. Manufacturing apparatus for pellets for a thixomolding injection molding machine having a configuration including a rod to be formed. 3. A method for producing pellets for a thixomolding injection molding machine from a molten metal in which waste material of a low melting point metal is melted, comprising: a mold having a large number of casting molds corresponding to the dimensions and shape of the pellets. A molten metal is poured into the casting mold while the mold is being moved and solidified to produce a pellet, and a pellet for a thixomolding injection molding machine is produced. 4. An apparatus for producing pellets for a thixomolding injection molding machine from molten metal obtained by melting waste material of a low melting point metal, comprising: a container for accommodating a molten metal; An apparatus for producing pellets for a thixomolding injection molding machine, comprising: a casting apparatus having a plurality of molds and a mold that moves in an endless track.