JP2001001110A - Chip for thixomolding machine and its manufacture, and its manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip for a thixomolding machine appropriate in size so that material is not clogged in a hopper or a cylinder of the thixomolding machine, and capable of manufacturing with excellent productivity. SOLUTION: A molten magnesium alloy 2 is fed in an inserting manner in a large number of recessed parts 9 formed in an outer circumferential surface on a rotary solidification roll 7 while flowing in a thin strip shape. The molten magnesium alloy 2 in the recessed parts 9 is cooled while the solidification roll 7 is rotated in a condition where the recessed parts 9 filled with the molten magnesium alloy 2 are covered. The recessed parts 9 are uncovered at the timing when a tip 12 is formed by cooling the molten magnesium alloy 2, and the chips 12 are pushed out and discharged from the recessed parts 9 by the operation of a depressible push-out pin 11 on a bottom surface of the recessed parts 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is used as a molding material for a thixomolding molding machine,
The present invention relates to a chip containing magnesium as a main component, a method for manufacturing the same, and a device for manufacturing the same.

[0002]

2. Description of the Related Art The thixotropic phenomenon is caused by adding vigorous agitation while cooling a liquid metal to a temperature lower than a liquidus temperature (a temperature at which all liquids are formed). This is a phenomenon in which the apparent viscosity of a molten metal in a solid-liquid coexisting state (semi-solidified state) is reduced due to a part of the metal being broken by shearing.
As a thixotropic metal exhibiting the thixotropic phenomenon, there are a magnesium alloy and an aluminum alloy.

In recent years, a thixomolding method for injection molding a metal slurry in a solid-liquid coexisting state in which a thixotropy metal has thixotropic properties has been put into practical use, and has attracted attention as a new injection molding method for magnesium alloys and the like. For example, application to thin-walled molded products such as parts for home appliances has been promoted. In this thixomolding molding machine, as in plastic injection molding, chips are formed into chips having a relatively small particle size that is convenient for melting a thixotropy metal molding material and supplied into the cylinder from a hopper. The chips of the molding material are heated and melted sufficiently by a heater provided outside the cylinder to form a liquid while being conveyed along a screw driven to rotate toward a nozzle serving as a tip outlet of the cylinder, and then rotated. While being subjected to a shearing force by the screw inside, it is cooled to a temperature lower than its liquidus temperature.

[0004] By the way, for example, a chip used as a molding material for a magnesium alloy thixomolding molding machine, if the shape is too large, air enters into the gap between the chips, so-called nests are formed in the molded product, and conversely, it is too small. Clogging occurs in the molding machine. Generally, a chip having a size of about 4 mm square is suitable as a molding material for a thixomolding molding machine.

[0005]

However, conventionally, a chip having the above-mentioned size is manufactured by cutting a cast ingot into a size of about 4 mm square using a cutting tool such as a lathe. Chip productivity is very low, which is a factor in increasing costs. Apart from this cutting method, as a method for producing a chip for a thixo molding machine, a means for cutting a rod-shaped alloy obtained by extruding from an extruder into a desired size is also known, but it is poor in mass productivity. Therefore, the appearance of a method for producing a chip for a thixomolding molding machine with high productivity has been awaited.

Therefore, it has been considered that magnesium-based metal powder used as a raw material for powder metallurgy products is directly used as a molding material for a thixomolding molding machine having high productivity. The reason is that this magnesium-based metal powder is easily available on the market. However, when a magnesium-based metal powder is supplied in powder form for a screw-type thixomolding molding machine that is used in a horizontal direction, clogging occurs in the hopper and cylinder, and the material is conveyed. Problem.

[0007] The magnesium metal powder is generally produced by the Atmanzu method. That is, the magnesium metal powder is sprayed with an inert gas such as argon or helium or a liquid such as a nonpolar solvent, mineral oil, alcohol or water as a spray fluid while dropping the molten magnesium metal. It is manufactured by spraying from the side and colliding, whereby droplets obtained by dividing the molten metal are dropped on a cooled disc and dispersed and quenched to form a powder. Since the magnesium metal powder produced in this manner usually has a size of 0.350 mm or less in all particles, in order to use this as a molding material for a thixomolding molding machine, a powder metallurgy technique or the like is used. It is necessary to have a desired size of about 4 mm square. Furthermore, since the magnesium metal powder produced by the above-mentioned Atmans method has a high oxygen content due to its surface being oxidized during the melting process, it is necessary to perform a treatment such as hydrogen reduction on the powder in order to obtain a high quality molded product. In the end,
The cost is high.

On the other hand, it is conceivable to manufacture chips for a thixomolding molding machine by a granulation method using a gas atomizing method. In this granulation method, high pressure air is blown from the side to the molten metal flow dropped from the upper part of the granulation chamber to break it into small droplets, and the small droplets are crushed into an inert gas atmosphere such as helium or argon in the granulation chamber. The metal particles are obtained by solidifying in the inside.

In this granulation method, since the molten metal droplets are cooled in an inert gas having an extremely low cooling performance, the droplets are made to reach the bottom of the granulation tank via a very long path. Large size particles can be obtained. However, in the case of a molten droplet of magnesium having a diameter of up to 1 mm, a granulation chamber having a height of about 7 m is required, and in the case of a molten droplet of magnesium having a diameter of 2 mm, a granulating chamber of about 21 m is required. A granulating chamber having a height is required, and the manufacturing apparatus becomes extremely large, and it cannot be practically used at all.

[0010] Another method of manufacturing chips for a thixomolding molding machine is to form a large number of molten light metals in a dispenser on an upper surface of a rotating drum having a horizontal axis of rotation by flowing the molten light metal into the upper surface of the rotating drum. The molten light metal is sequentially poured into the small recesses from above without contacting air, and the molten light metal collected in the recesses is conveyed downward with the rotation of the rotating drum while being cooled so as not to spill and solidified. There has been proposed a method of dropping a granular lump formed below a rotating drum (see Japanese Patent Application Laid-Open No. 6-10013). However, in this method, when removing the granular mass from the concave portion, high-pressure air is blown from the rear side in the rotation direction toward the outer surface of the rotating drum, or the brush is brought into contact with the outer peripheral surface of the rotating rotary drum, There is a drawback in that the state in which the granular mass is taken out varies due to the high temperature, and it is difficult to reliably obtain a granular mass of a desired shape.

In view of the above, the present invention has been made in view of the above-mentioned conventional problems, and has a suitable size that does not cause clogging in a hopper or a cylinder of a thixomolding molding machine and can be manufactured with high productivity. It is an object of the present invention to provide a molding machine chip, a method for manufacturing the same, and a device for manufacturing the same.

[0012]

In order to achieve the above object, a method for manufacturing a chip for a thixomolding molding machine according to the present invention is directed to a solidifying roll which rotates while flowing a molten metal in which a magnesium alloy is melted as a thin strip. The molten metal in the concave portion is cooled while being supplied while being inserted into a plurality of concave portions formed on the outer peripheral surface of the outer peripheral surface while rotating the solidification roll while covering the concave portion filled with the molten metal. At the timing when the chips are formed by cooling the molten metal, the cover of the concave portion is released, and the tip is pushed out from the concave portion and discharged by the operation of a push pin which can be protruded and retracted on the bottom surface of the concave portion. It is characterized by doing.

In this method for manufacturing chips for a thixomolding molding machine, chips are manufactured by rapidly cooling the molten metal filled in the recesses in a state where the molten metal is covered so as not to be spilled, and the finished chips are extruded by operating the extruding pins. Therefore, there is no variation in the shape of the chip when it is discharged from the recess, and a chip having a size and shape determined by the shape of the recess can be reliably obtained. In addition, chips can be manufactured with high productivity by a series of continuous steps in which the molten metal is supplied to the concave portion of the solidification roll and rapidly cooled as the solidification roll rotates.

Since the chip for a thixomolding molding machine of the present invention is manufactured by the above-described manufacturing method of the present invention, it has a size and a shape determined by the shape of the concave portion, and has a powder forming step and the like. As a result, the oxygen content is remarkably low and high quality is obtained.

Further, the apparatus for manufacturing chips for a thixomolding molding machine according to the present invention comprises a melting furnace for melting a magnesium alloy, and a molten metal of the magnesium alloy supplied from the melting furnace, which is strip-shaped by a predetermined amount from a slit-shaped hot water supply port. And a pair of solidifying rolls that are arranged parallel to each other in the horizontal direction with a small gap, and rotate in opposite directions to guide the molten metal supplied from above to the gap. The solidifying roll is provided with a recess having a shape corresponding to the shape of the chip to be manufactured, formed on the entire outer periphery, and provided with a push-out pin which can be protruded and retracted from the bottom of each of the recesses, and has a built-in cooling means. The other solidifying roll has a small gap in which a portion of the outer peripheral surface facing one solidifying roll can cover each of the concave portions. Wherein together are oppositely arranged in one of the coagulation rolls have become built comprising constitute a cooling means.

The apparatus for manufacturing chips for a thixomolding molding machine faithfully embodies the method for manufacturing chips for a thixomolding molding machine of the present invention, and in addition to reliably obtaining the effects of the manufacturing method, a hot water supply apparatus Since the molten metal flows down from the hot water supply port to the gap between the pair of solidification rolls, the apparatus does not increase in size, and the cover of the recess is installed in parallel with one solidification roll with a small gap. Since the configuration is a rational one performed by the other solidifying roll, the manufacturing method of the present invention can be realized while simplifying the configuration.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a chip manufacturing apparatus embodying the method for manufacturing a chip for a thixomolding molding machine of the present invention. In FIG. 1, a melting furnace 1 melts a magnesium alloy (not shown) inserted as a chip material in a flowable state. The molten metal 2 of the magnesium alloy melted so as to be able to flow in the melting furnace 1 flows down into the hot water supply device 3 and then forms a strip from the hot water supply opening 4 formed at the lower end of the hot water supply device 3 in a slit shape. Down by a certain amount. The molten metal 2 flowing down from the hot water supply port 4 is supplied from above to a small gap between a pair of solidifying rolls 7 and 8 which are opposed to each other in parallel at a predetermined gap and are driven to rotate in different directions.

One coagulating roll 7 of the pair is
As shown in FIG. 1, concave portions 9 are arranged vertically and horizontally over the entire outer periphery. As shown in FIG. 3, which is an enlarged perspective view of a main part of the solidification roll 7, the concave portion 9
Thus, the shape is adapted to the chip to be formed. In addition, an insertion hole 10 is formed at the center of the bottom of each of the recesses 9, and as shown in FIG. Are provided so that they can come and go. Before the molten metal 2 is inserted, the push pin 11 retreats to a position where the front end surface thereof is flush with the bottom surface of the concave portion 9 and closes the insertion hole 10 as shown in FIG.

The molten metal 2 is supplied into the recess 9 in a state where the bottom surface of the insertion hole 10 is closed by the pushing pin 11 at the retracted position. Here, the outer peripheral surface portions of the two solidifying rolls 7, 8 facing the one solidifying roll 7 in the other solidifying roll 8 with a small gap are formed at the timing when the molten metal 2 is filled in the concave portion 9. Opposing each other with a gap that can function to cover the opening. As a result, the molten metal 2 is transported downward with the rotation while maintaining the state filled in the recess 9.

At the time of the above transfer, the molten metal 2 in the concave portion 9 is rapidly cooled by cooling means built in both solidifying rolls 7 and 8 to become a chip 12 having a desired shape set by the concave portion 9. The chip 12 formed by quenching the molten metal 2 in the concave portion 9 is transported to the lower side by the rotation of the solidifying roll 7, and when the cover is released by the separation of the other solidifying roll 8, a drive (not shown) is started. It is pushed out of the recess 9 by a push pin 11 which is actuated by a mechanism to project inward of the recess 9. In addition, inside of both solidification rolls 7 and 8,
Cooling means is built in, and as this cooling means, a well-known configuration such as a cooling pipe can be used.
The illustration is omitted.

In the embodiment of the chip manufacturing apparatus, the melting furnace 1 heats and melts a magnesium alloy at a high temperature of about 650 ° C. The hot water supply device 3 is heated to a high temperature of about 650 ° C. like the melting furnace 1. Thereby, the molten metal 2 inserted from the melting furnace 1 to the hot water supply device 3 flows down from the hot water supply port 4 in a belt shape while maintaining the same state as the melting furnace 1. Hot water supply port 4 of hot water supply device 3 is formed in a slit shape having a width of 2 mm, and allows molten metal 2 to pass through as a band shape having a width of 2 mm.
Both coagulating rolls 7, 8 have a diameter of 100 mm and
It is rotated at a constant speed of 0 rpm. Both the vertical dimension A and the horizontal dimension B are 3 mm on the entire outer peripheral surface of one solidifying roll 7.
And a recess 9 having a depth of 2 mm is formed vertically and horizontally. The diameter of the push pin 11 is set to 1.5 mm.

As shown in FIG. 4, the side wall surface 9a of the concave portion 9 has a tapered shape which expands outward, so that the tip 12 formed by solidification of the molten metal 2 in the concave portion 9 is formed. Can be easily discharged from the concave portion 9 by the push pin 11. In addition, the concave portion 9 is not limited to a rectangular shape, and may have an arbitrary shape such as a hemisphere.
That is, by changing the shape of the concave portion 9, a chip 12 having a desired shape can be obtained.

In this chip manufacturing apparatus, the concave portion 9 is covered with the outer peripheral surface of the other solidifying roll 8 at the timing when the molten metal 2 fills each concave portion 9 of the one solidifying roll 7.
Since the molten metal 2 is rapidly cooled while the solidifying rolls 7 and 8 are rotating while maintaining a state in which the molten metal 2 is filled therein, the chip 12 having a desired size and shape determined by the shape of the concave portion 9 is reliably formed. This chip 12 can be manufactured and
It can be manufactured with high productivity by a series of simple steps.

Further, since the configuration is such that the molten metal 2 flows down from above from the hot water supply port 4 of the hot water supply device 3 into the gap between the pair of solidifying rolls 7 and 8, the size of the device does not increase. further,
Since the means for covering the concave portion 9 at the timing when the molten metal 2 is filled is a rational configuration in which the other solidifying roll 8 is provided in parallel with the one solidifying roll 7 with a small gap, it is a reasonable configuration. The desired effect can be obtained while simplifying the structure, and the device can be further reduced in size. Further, the chip 12 for the thixomolding molding machine obtained by this manufacturing apparatus does not have a powder forming step or the like, so that the oxygen content is remarkably small and high quality.

[0025]

As described above, according to the method of manufacturing a chip for a thixomolding molding machine of the present invention, the chip is extruded by the operation of the extruding pin. This does not occur, and a chip having a size and a shape determined by the shape of the concave portion can be reliably obtained. In addition, chips can be manufactured with high productivity by a series of continuous steps in which the molten metal is supplied to the concave portion of the solidification roll and rapidly cooled as the solidification roll rotates.

The chip for a thixomolding molding machine according to the present invention has a size and a shape determined by the shape of the concave portion, and does not have a powder forming step in the manufacturing process. And high quality.

According to the apparatus for manufacturing a chip for a thixomolding molding machine of the present invention, the method of manufacturing the chip for a thixomolding molding machine of the present invention can be faithfully embodied, and the effects of the manufacturing method can be reliably obtained. In addition, since the molten metal flows down from the hot water supply port of the hot water supply device into the gap between the pair of solidification rolls, the apparatus does not increase in size, and the cover of the concave portion is provided with a small gap between one of the solidification rolls. And the other is a rational configuration in which the other solidification rolls are provided in parallel, so that the manufacturing method of the present invention can be embodied while simplifying the configuration.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a chip manufacturing apparatus embodying a method for manufacturing a chip for a thixomolding molding machine according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a pair of solidification rolls in the chip manufacturing apparatus.

FIG. 3 is an enlarged perspective view of a main part of the solidification roll;

FIG. 4 is a sectional view of a main part of the solidifying roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Molten metal 3 Hot water supply device 4 Hot water supply port 7 One solidification roll 8 The other solidification roll 9 Concave part 11 Extrusion pin 12 Tip

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B22D 29/04 B22D 29/04 C

Claims (3)

[Claims] 1. A melt in which a magnesium alloy has been melted is supplied as being inserted into a plurality of recesses formed on an outer peripheral surface of a rotating solidification roll while flowing down as a thin strip, and the melt is filled inside. Cooling the molten metal in the concave portion while rotating the solidifying roll in a state where the concave portion is covered, releasing the lid of the concave portion at a timing when chips are formed by cooling the molten metal, and Characterized in that the tip is pushed out of the recess by a push-out pin which can be retracted from the bottom surface of the chip and discharged. 2. A chip for a thixomolding molding machine manufactured by the manufacturing method according to claim 1. 3. A melting furnace for melting a magnesium alloy, a hot water supply device for flowing a predetermined amount of molten magnesium alloy supplied from the melting furnace in a strip shape from a hot water supply opening in a slit shape, and a small gap in a horizontal direction. Placed parallel to each other,
And a pair of solidifying rolls that rotate in opposite directions so as to guide the molten metal supplied from above to the gap, and one solidifying roll has a concave portion having a shape corresponding to the shape of the chip to be manufactured on the entire outer periphery. A push pin is formed and is provided on each bottom surface of each of the recesses so as to be freely protruded and retracted, and a cooling means is built in. The other solidifying roll faces one solidifying roll on its outer peripheral surface. A portion to be provided is opposed to the one solidifying roll with a small gap that can cover each of the concave portions,
An apparatus for manufacturing a chip for a thixomolding molding machine, comprising a cooling means built-in.