JP2010069538A - Method and apparatus for manufacturing pellet for use in injection molding machine of thixomolding method - Google Patents

Abstract

[PROBLEMS] To establish a technology capable of producing pellets having a certain shape and size with high accuracy and high efficiency in producing raw materials for a thixomolding injection molding machine.
A pellet manufacturing apparatus includes a moving mold that can move in an endless track manner by connecting a large number of T-shaped mold members. Molten metal is injected into the mold member 52 in a horizontal state in which a semicircular cut-out section formed at the rear end and the front end of the upper member of the adjacent mold member 52 is abutted to form a casting hole mold having a circular cross section. To solidify. Then, when the mold member 52 arrives at the reversal point, the front and rear mold members 52 that are in contact with each other are separated, and the metal solidified in the casting hole mold is dropped from the casting hole mold at the reversal point. It is dropped into the hopper 58 and stored.
[Selection] Figure 6

Description

  The present invention relates to a method and an apparatus for producing pellets used as raw materials in low-melting-point alloy injection molding, particularly thixomolding injection molding.

  Magnesium and magnesium alloys (hereinafter referred to as magnesium alloys) are recently attracting attention as low melting point alloys. Magnesium alloys are the lightest structural metals in practical use, have high specific strength (proof strength / specific gravity), and have excellent properties as structural bodies in terms of dimensional stability and vibration absorption. For this reason, it is widely used in automobiles, aviation, space equipment, home appliances, leisure / sports equipment, and other machine parts.

  Magnesium alloy forming methods are roughly classified into 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 thixo molding method in which a melting step is omitted and a raw material is supplied in a semisolid state. The thixomolding method is a semi-solid state in which a magnesium alloy pellet or chip material is charged into a hopper, and the pellet or chip is heated in a cylinder above the freezing point and below the melting point by a heater. And then injecting it into the mold.

  This thixomolding method has many advantages over the die-casting method. In particular, (1) No melting furnace or large fire prevention measures are required in the factory, (2) No melting technology or experience is required, (3) Energy It is excellent in terms of cost reduction, (4) a thin molded product can be produced, (5) bubbles are hardly formed in the molded product, (6) molding cycle time is short, and (7) scrap can be recycled.

  Regarding the recycling of magnesium alloy scrap, as a method of manufacturing pellets or chips for raw materials for thixomolding injection molding, waste materials (including return materials, the same applies hereinafter) are cut and crushed into chips, and the waste materials are melted. Or extruding into pellets or chips.

  As a method by cutting and crushing, for example, there is a method described in JP 2000-33279 A (Patent Document 1). In this method, the waste material is cut and crushed to obtain a primary crushed material, and the primary crushed material is cut and cut with a fixed blade and a rotary blade, and passed through a screen to obtain a chip.

  As a method by melting and extrusion, for example, there are methods described in JP-A-11-123373 (Patent Document 2) and JP-A-11-123502 (Patent Document 3). The method described in Japanese Patent Application Laid-Open No. 11-123373 (Patent Document 2) is a method in which waste material is heated and pressed into a molten or semi-solidified softened state, extruded from a nozzle, and formed into a rod-shaped body and cut. In addition, the method described in JP-A-11-123502 (Patent Document 3) is a method in which waste materials are heated and kneaded to form a semi-solid body, and extruded from a die and cut into pellets.

JP 2000-33279 A Japanese Patent Laid-Open No. 11-123373 JP-A-11-123502

  There are advantages and disadvantages to the method of producing chips by cutting and crushing and the method of producing pellets or chips by melting and extruding, as methods for producing recycled chips for thixomolding injection molding machines. The method of cutting and crushing into chips has the advantages of reducing energy and eliminating the need for waste gas, dross, and sludge treatment compared to the previous method of remelting and refining waste materials to make ingots and using them as rechips. On the other hand, there are problems that impurities are mixed into the alloy itself by cutting and crushing and fine powder with high explosiveness is generated. In addition, the method of forming pellets or chips by melting and extruding is advantageous in that there is less variation in the shape of the pellets or chips compared to the method by cutting and crushing, and fine powder is not generated, while the apparatus is enlarged. There is a problem that it is difficult to control the cooling rate of pellets or chips.

  Such a problem is not limited to a magnesium alloy, but is a problem common to thixomolding injection molding 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 that when a raw material for a thixomolding injection molding machine is manufactured by melting and forming a low melting point metal waste material such as a magnesium alloy, pellets of a certain shape and size are produced with high accuracy and high accuracy. The goal is to establish a technology that can be manufactured efficiently.

  The present invention is a method for producing pellets for a thixomolding injection molding machine from a molten metal obtained by dissolving a waste material of a low-melting-point metal such as a magnesium alloy, wherein the molten metal is sucked into a cylinder, and the opening of the cylinder It is characterized in that a semi-solid state metal is extruded from the inside of the cylinder by the movement of the rod that advances and retreats from the cylinder, and is cut into a certain length to produce pellets.

  The pellet manufacturing method includes a container for storing molten metal and a cylinder for forming a pellet by extruding the molten metal sucked from the container, and the cylinder has a molten metal extrusion port at the lower end and an upper end. The piston can be implemented using an apparatus having a suction port for molten metal at an intermediate portion and a rod that moves forward and backward through the piston and the extrusion port.

  When manufacturing pellets for thixomolding injection molding machines using this equipment, the waste material produced by appropriately cutting and crushing scrap materials and product waste generated in the low melting point metal manufacturing process is melted in a melting furnace. After degassing, impurity removal and component adjustment according to the above, the molten metal is accommodated in a container, and the molten metal is sucked from the container into a pellet forming cylinder to produce pellets of low melting point metal.

  Since the pellet forming cylinder has a molten metal suction port, an extrusion port, and a piston, and has a structure including a piston and a rod that advances and retreats through the extrusion port, the piston is retracted and the molten metal is removed from the molten metal container. By sucking into the cylinder, moving the piston forward and backward with the suction port closed, a certain amount of semi-solid metal is extruded from the extrusion port and cut into a certain length to produce pellets .

  At this time, by inserting 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 the rod advances. When this occurs, the semi-solid metal is pushed out of the extrusion port by the internal pressure of the cylinder. The amount of extrusion of semi-solid metal is determined by the stroke amount of the piston, that is, the pressure of the enclosed inert gas, the amount of advancement of the rod, the time, that is, the stroke amount of the rod that moves forward and backward, and the cycle, and the size of the pellet can be adjusted by this. it can.

  In addition, as a method of manufacturing pellets for thixomolding injection molding machines, low melting point metal waste material was dissolved in the casting hole mold while moving a mold in which many casting hole molds corresponding to the size and shape of the pellet were moved. It is also possible to employ a method in which molten metal is injected and solidified into pellets.

  The above pellet manufacturing method includes an apparatus having a configuration including a container for storing molten metal, and a casting apparatus having a casting mold that forms a large number of casting hole molds corresponding to the size and shape of the pellet and moves in an endless track manner. Can be implemented.

  When producing pellets using this device, melt the waste material of low melting point metal, store the molten metal after degassing, impurity removal, and component adjustment as necessary, and use the molten metal from this container. Are sequentially injected into a casting mold of a moving mold of a casting apparatus and solidified to produce pellets.

  Thus, according to the method and apparatus of the present invention, pellets for a thixomolding injection molding machine can be automatically and efficiently produced from a molten metal obtained by dissolving a low melting point metal waste material. In particular, if the apparatus of the present invention is installed at the front stage of a 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 do.

  A method of producing pellets by sucking molten metal in which a waste material of low melting point metal such as magnesium alloy is melted into a cylinder and extruding a semi-solid state metal from the cylinder by the movement of a rod that advances and retreats from the opening of the cylinder, or The thixotrope is made by injecting molten metal in which low melting point metal waste is melted into a casting hole mold and solidifying it into a pellet by moving a mold in which many casting hole molds corresponding to the size and shape of the pellet are moved. By producing pellets for a molding method injection molding machine, pellets having a certain shape and size can be produced automatically and continuously and efficiently. In addition, if the pellet manufacturing apparatus of the present invention is installed at the front stage of a thixomolding injection molding machine and the manufactured pellets are put into the raw material hopper of the injection molding machine, the pellet manufacturing and injection molding lines will be continuous. can do.

It is a figure which shows the whole structure of the injection molding equipment of the magnesium alloy in embodiment of this invention. It is a figure which shows the structure and operating principle of a pellet manufacturing apparatus. (A) is a partially cutaway front view showing the structure of the cylinder of the pellet manufacturing apparatus, and (b) is a cross-sectional view taken along line AA of (a). (A) is a partially cutaway front view showing the structure of the piston, (b) is a cross-sectional view taken along the line BB of (a). (A) is a partially cutaway front view showing the structure of the rod, and (b) is a sectional view taken along the line CC of (a). It is the schematic which shows the structure of the casting apparatus which is another embodiment of a pellet manufacturing apparatus. It is a perspective view of the member which comprises a casting_mold | template. It is a fragmentary perspective view which shows the arrangement | positioning relationship between an injection apparatus and a casting_mold | template.

  FIG. 1 is a diagram showing an overall 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 that pellets and recycles magnesium alloy waste, 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 apparatus 10 includes a melting furnace 11, a charging apparatus 12 for continuously feeding the magnesium alloy waste material into the melting furnace 11, and a supply pipe 13 for supplying the molten metal to the molten metal container 20. Such a melting apparatus itself is known. The molten metal is supplied to the molten metal container 20 continuously or intermittently by an electromagnetic pump 14 provided in the middle of the supply pipe 13. The molten metal container 20 is a container similar to a conventionally known container.

  The injection molding machine 40 includes a molding machine main body 41, a mold 42, and a raw material pellet charging hopper 43 supplied from the pellet manufacturing apparatus 30, and such an injection molding machine itself is known. The pellets charged into the molding machine main body 41 from the charging hopper 43 are heated in the cylinder by the heater in the molding machine main body 41 to a temperature higher than the freezing point and lower than the melting point, and put into the mold in a semi-solid state where the liquid phase and the solid phase coexist. The product P is injected and molded into a predetermined shape. This injection molding machine itself is known.

  2 is a diagram showing the structure and operating 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. 2 (b) is an AA line in FIG. 4A is a partially cutaway front view showing the structure of the piston, FIG. 4B is a sectional view taken along the line BB of FIG. 5A, and FIG. 5A is a part showing the structure of the rod. A notched front view and FIG. 7B are cross-sectional views taken along the line CC of FIG.

  First, the structure of the pellet manufacturing apparatus 30 will be described. The pellet manufacturing apparatus 30 includes a cylinder 31, a piston 32, and a rod 33. The pellet manufacturing apparatus 30 sucks molten metal into the cylinder 31, and extrudes a semi-solidified metal from the cylinder 31 to form a pellet. The cylinder 31 has a molten metal extrusion port 31a at the lower end, a piston 32 at the upper end, and a molten metal suction port 31b at the middle, and the rod 33 advances and retreats through the piston 32 and the extrusion port 31a. It has become.

  As shown in FIG. 3A, the extrusion port 31 a at the lower end of the cylinder 31 is formed following the through hole 31 c of the rod 33 and has the same shape as the outer shape of the lower end of the rod 33. Further, as shown in FIG. 2B, the extrusion port 31a is provided with eight holes 31d communicating with the bottom surface of the cylinder 31 and the inner surface of 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 portion of the cylinder 31 so as to be able to move up and down by sliding on the inner surface of the cylinder 31. The shape to be formed.

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

  Next, the operating principle of the pellet manufacturing apparatus 30 will be described. In FIG. 2, (a) shows an intake cycle, (b) shows a pressurization cycle, (c) shows a molding cycle, and (d) shows a cutting cycle.

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

  The pressurization cycle is a step of pressurizing the molten metal M in the cylinder 31. As shown in FIG. 2B, when the piston 32 is pushed down, the suction port 31b is closed and the gas filling space 34 is closed. The internal pressure of the argon gas 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 material in a state of being pressurized in the cylinder 31 is melted. The metal M is pushed out from the hole 31d on the cylinder bottom toward the push-out port 31a. The molten metal M extruded to the extrusion port 31a is in the form of a slurry in a solid-liquid coexistence state, and is in a semi-solid state near the outlet.

  The semi-solid state metal slurry extruded to the extrusion port 31a is sheared by the hole 33b of the expanding portion 33a of the ascending rod 33, and is discharged out of the apparatus in the form of being cut into a cylindrical 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. Is pushed upward, the enlarged portion 33a at the lower end of the rod 33 returns to the inside of the extrusion port 31a, and after the semi-solid metal extruded through the hole 31d is cut by the molding cycle, the semi-solid metal flows out of the hole 31d. stop.

  By repeating the above four cycles, pellets of a certain size are formed in the molding cycle. In this molding cycle, the amount of extrusion 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 accordingly.

  The pellet manufacturing apparatus 30 is installed on the upper portion of the charging hopper 43 of the injection molding machine 40, and the molten metal suction port 31b of the cylinder 31 is connected to the molten metal storage container 20 via the suction pipe 35. The molten metal is sucked through the suction pipe 35 to produce pellets as a raw material for the injection molding machine 40. In this manner, pellets for a thixomolding injection molding machine can be automatically and efficiently produced from a molten metal in which a low melting point metal waste such as a magnesium alloy is dissolved.

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

  The pellet manufacturing apparatus 50 includes an endless track moving mold 51, a molten metal injection apparatus 53, a shielding apparatus 55, and the like, and is an apparatus that manufactures pellets by casting molten metal.

  The moving mold 51 is configured by connecting a large number of T-shaped mold members 52 and moving in an endless track manner. The mold member 52 is made of a surface-nitrided alloy tool steel, and includes an upper member 52b, a column member 52c, and connecting members 52d and 52e forming a casting hole mold 52a, as shown in FIG. When casting mold 52 is in a horizontal state, notches 52a-1 and 52a-2 having a semicircular cross section formed at the rear end and the front end of upper member 52b of adjacent mold member 52 are brought into contact with each other for casting with a circular cross section. The hole mold 52a is obtained. The casting hole mold 52a has an inner diameter of 1 mm and a depth of 1 mm. After molten metal is injected into the casting hole mold 52a and solidifies, it becomes a rod-shaped pellet having an outer diameter of 1 mm and a length of 1 mm. Connecting members 52d and 52e are provided with connecting holes 52f and 52g, respectively, and connecting rods (not shown) are inserted into these holes to connect adjacent mold members 52.

  As shown in FIG. 8, the moving molds 51 are arranged in three rows in the mold moving direction, and a plurality of these three rows of connected mold members 52 are wound around the drive gear 54 as shown in FIG. It is configured to be able to move intermittently. The periphery of the moving mold 51 is blocked from the outside air by the shielding device 55, and argon gas is blown in from the outside through the pipes 56 and 57, thereby cooling the periphery and inactivating the atmosphere.

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

  Pellets are produced by the casting apparatus having the above-described configuration as follows. Molten metal is sequentially injected from the injection nozzle 53b of the tundish 53a into the casting hole mold 52a, and the mold member 52 is sequentially moved by a fixed distance corresponding to the interval of the casting hole mold 52a at a fixed time interval corresponding to the injection time. . The molten metal injected into the casting hole mold 52a is solidified and cooled during the movement, and as shown in FIG. 6, when the mold member 52 arrives at the reversal position, the front and rear mold members 52 that are in contact with each other are separated. Since it is divided, the metal solidified in the casting hole mold 52a drops off from the casting hole mold 52a at the reversal point and falls into the hopper 58 to be accommodated.

  The pellet manufacturing apparatus 50 is installed above the injection molding machine 40 so that the hopper 58 is positioned above the charging hopper 43 (see FIG. 1) of the injection molding machine 40, and the molten metal in the molten metal container 20 shown in FIG. Metal is supplied to the tundish 53a through a supply pipe (not shown), and pellets that are raw materials for the injection molding machine 40 are manufactured.

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

DESCRIPTION OF SYMBOLS 10 Melting | dissolving apparatus 11 Melting furnace 12 Loading apparatus 13 Supply pipe 14 Electromagnetic pump 20 Molten metal storage container 30 Pellet manufacturing apparatus 31 Cylinder 31a Extrusion port 31b Suction port 31c Through-hole 31d Hole 32 Piston 32a Through-hole 33 Rod 33a Expansion part 33b Hole 34 Gas filling space 35 Suction tube 40 Injection molding machine 41 Molding machine main body 42 Mold 43 Loading hopper 50 Pellet manufacturing device 51 Moving mold 52 Mold member 52a Casting hole 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

Claims (2)

A method for producing pellets for a thixomolding injection molding machine from a molten metal obtained by dissolving a low melting point metal waste material,
A casting mold corresponding to the size and shape of the pellet by moving the endless track type movable mold connected with a large number of mold members while the notches formed at the front and rear ends of adjacent mold members are abutted with each other. The molten metal contained in a container is poured into the mold member in a horizontal state to be solidified, and when the mold member arrives at the reversal point, the front and rear mold members that are in contact with each other are separated, so that the casting hole A method for producing a pellet for a thixomolding injection molding machine, wherein the pellet is produced by dividing a mold. An apparatus for producing pellets for a thixomolding injection molding machine from molten metal in which low melting point metal waste is dissolved,
A container for containing molten metal, and a casting apparatus having an endless track type movable mold in which a large number of mold members having molten metal as pellets are connected,
When the mold member is in a horizontal state, the moving mold becomes a casting hole mold corresponding to the size and shape of the pellet by abutting notches formed at the front end and the rear end of adjacent mold members. An apparatus for manufacturing pellets for a thixomolding injection molding machine, wherein the front and rear mold members that are in contact with each other when the member arrives at the reversal point are separated.

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