JP2007105746A - Injection molding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding apparatus having a hopper which can easily supply clean molten metal. <P>SOLUTION: In the injection molding apparatus, the molten metal is produced by melting an ingot 500 by means of a crucible 11 and is stored in the hopper 12. The crucible 11 and the hopper 12 are arranged at almost the same height, and the height of the liquid surface of the molten metal in the crucible 11 and the hopper 12 is set to be almost the same. Further, piping 130 for connecting the crucible 11 and the hopper 12 is arranged so as to be lower than the height of the liquid surface of the molten metal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an injection molding apparatus that forms a molten metal by melting a metal material such as a magnesium alloy.

  Conventionally, various apparatuses have been disclosed for melting metal materials such as magnesium alloys. For example, Patent Document 1 discloses a metal injection molding apparatus capable of downsizing the apparatus.

According to the metal injection molding apparatus of Patent Document 1, a configuration is adopted in which air in the loader tank is sucked and decompressed by a jet of compressed air, and a metal material chip is sucked into the loader tank from the material tank. As a result, the loader body can be prevented from being placed on the floor, and the apparatus can be miniaturized.
JP 2000-135553 A

  However, in the metal injection molding apparatus described in Patent Document 1, even when impurities are mixed when the material is supplied from the loader tank to the hopper, the molten metal containing impurities is supplied from the hopper to the injection molding apparatus as it is. Is done. As a result, a molded product containing impurities is manufactured, and defective products are generated.

  The objective of this invention is providing the injection molding apparatus provided with the hopper which can supply a clean molten metal easily.

Means and effects for solving the problems

(1)
An injection molding apparatus according to the present invention is an injection molding apparatus for injecting a molten metal into a mold at a predetermined pressure, and a crucible for melting a metal to produce a molten metal, and a molten metal melted by the crucible. A holding hopper, and a pipe connected to the crucible and the hopper so that the crucible and the hopper are connected to each other below the liquid level of the molten metal. A crucible and a hopper are provided so as to be approximately equal to the liquid level of the molten metal.

  In the injection molding apparatus according to the present invention, a metal is melted by a crucible to produce a molten metal, and the molten metal produced by the crucible is held by a hopper through a pipe. Moreover, piping is provided below the liquid level height of a molten metal.

  In this case, since the liquid level of the molten metal in the crucible and the hopper is set to be substantially equal, if the liquid level of the molten metal in the crucible rises due to the metal charged in the crucible, According to the principle, the liquid level in the hopper also rises and the liquid levels are almost equal to each other. As a result, a device such as a pump for sending the molten metal from the crucible to the hopper is not required, so that the configuration of the injection molding apparatus can be simplified, and it is not necessary to transport the heated molten metal over a long distance. The holding energy of the molten metal can be reduced.

  Moreover, since the piping is provided below the liquid level, impurities (for example, metal oxides) floating on the liquid level of the molten metal in the crucible can be prevented from moving to the hopper side. As a result, it is possible to reduce the defective rate of a molded product molded by the injection molding apparatus. Furthermore, since the crucible can be moved upward, the foot space can be effectively used.

(2)
The injection molding apparatus further includes a barrel portion provided with a metal melt supply port at an upper portion and provided with a screw for moving the metal melt supplied from the supply port therein, and the hopper is disposed below the pipe with the metal melt. And a supply pipe connected to the supply port of the barrel portion.

  In this case, the molten metal can be supplied from the hopper through the supply pipe to the supply port. In addition, since the supply pipe is arranged below the pipe, the liquid level is greatly lowered unexpectedly, and even when impurities (for example, metal oxides) flow into the hopper from the crucible, At that time, it is possible to prevent impurities existing on the liquid surface of the molten metal from being supplied to the barrel portion.

(3)
The crucible may have an open / close lid into which metal can be put. In this case, metal can be thrown in by opening the open / close lid of the crucible. Further, since the opening / closing lid can be closed except when the metal is added, the airtightness can be improved. As a result, it is possible to prevent the metal melt from coming into contact with the outside air and generating oxides.

(4)
The hopper may include a heat retaining device capable of maintaining the molten metal. In this case, the molten metal can be maintained in an optimum state by the heat retaining device provided in the hopper.

(5)
The crucible may be sealed and may have a gas supply device capable of supplying an inert gas into the crucible. In this case, oxidation of the molten metal melted in the crucible can be prevented.

(6)
The hopper may be sealed and may have a gas supply device capable of supplying an inert gas into the hopper. In this case, oxidation of the molten metal stored in the hopper can be prevented.

(7)
You may further include the liquid level detection apparatus which detects the liquid level in a crucible and / or the liquid level in the said hopper, and the injection | throwing-in apparatus which throws a metal into a crucible automatically based on the signal from a liquid level detection apparatus.

  In this case, when the amount of the molten metal in the hopper is reduced based on the signal from the liquid level detection device, the charging device puts the metal into the crucible. As a result, a shortage of molten metal in the hopper can be prevented.

(8)
The barrel part may have an airtight seal part at a position higher than the liquid level in the crucible and the hopper.

  In this case, since the seal part of the barrel part is disposed at a position higher than the liquid level in the crucible and the hopper, the seal part does not come into contact with the molten metal supplied from the hopper, so that the seal part is not damaged. Moreover, the sealing part can maintain the sealing degree of the barrel part, and oxidation of the molten metal can be prevented in the barrel part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(One embodiment)
FIG. 1 is a schematic view showing an example of an injection molding apparatus according to an embodiment of the present invention.

  An injection molding apparatus 100 shown in FIG. 1 mainly includes a molding material charging unit 10, a vertical mold arrangement barrel unit 20, a cylinder unit 30, and a mold clamping unit 40.

  The molding material charging unit 10 includes a melting furnace 11 and a hopper 12. The vertical arrangement barrel unit 20 includes a barrel 21, a screw 22, a storage unit 23, a cooling means 24 (a plurality of temperature control jackets 24a), a communication channel 25, a drive motor 26, a screw hydraulic cylinder 27, a supply port 28, and a cylinder. A rod 29 is included.

  The cylinder unit 30 includes a cylinder 31, a plunger 32, a plunger injection device 33, a metering unit 34, a nozzle unit 35, a valve device 36, and a plunger hydraulic cylinder 37. The mold clamping unit 40 includes a base 41, a link housing 42, a tie bar 48, a fixed plate 44, a movable plate 45, a mold clamping cylinder 46, a cylinder rod 47, a plurality of links 43, an extrusion cylinder 49a, and an extrusion rod 49b. The mold 60 includes a fixed mold 61 and a moving mold 62.

  Hereinafter, the injection molding apparatus 100 according to the present embodiment will be described. In the injection molding apparatus 100 according to the present embodiment, a vertically arranged barrel unit 20 is connected to a molding material charging unit 10. A cylinder part 30 is provided below the vertically arranged barrel part 20, and a mold clamping part 40 is provided in the cylinder part 30 so as to communicate therewith. The mold clamping unit 40 is provided with a mold 60.

  The melting furnace 11 of the molding material input unit 10 of the injection molding apparatus 100 is provided in communication with the hopper 12 through a pipe 130 as will be described later. The hopper 12 receives the molten metal MF melted in the melting furnace 11 and stores it in a molten state. The lower end opening of the hopper 12 communicates with a supply port 28 of the barrel 21 described later. The detailed structure of the molding material charging unit 10 will be described later.

  A supply port 28 to which the molten metal MF is supplied is provided at the upper part of the barrel 21 of the vertically arranged barrel portion 20 arranged substantially vertically. Inside the barrel 21, there is provided a screw 22 that is rotatable and can be moved back and forth in the axial direction of the barrel 21. As the screw 22 moves backward, a reservoir 23 is formed in the lower portion of the barrel 21.

  Further, a drive motor 26 is directly connected to the upper end of the barrel 21, and a screw hydraulic cylinder 27 having a cylinder rod 29 extending and retracting in the vertical direction is connected to an upper portion of the drive motor 26. The drive shaft of the drive motor 26 is a cylindrical hollow shaft type, and the cylinder rod connected to the upper end of the screw 22 rotatably inserted into the barrel 21 can be moved in the axial direction and rotated. It is inserted so as to be fixed in the direction. The screw 22 is arranged in a cantilever shape so that the lower end thereof is a free end in the barrel 21.

  For this reason, in the screw extruder according to the present embodiment, the semi-solid slurry is stored in the storage portion 23 at the lower end of the barrel 21 while rotating the screw with the drive motor, and the cylinder rod of the hydraulic cylinder 27 for the screw is stored. By projecting 29 downward, the screw 22 is moved downward in the axial direction, so that the semi-solid slurry HS accumulated in the reservoir 23 can be pushed out of the barrel.

  The outer peripheral surface of the barrel 21 is covered with cooling means 24. The cooling means 24 includes a plurality of temperature control jackets 24a separated in the vertical direction. Then, by circulating a heat medium such as oil lower than the temperature of the molten metal MF in the temperature control jacket 24a, the molten metal MF in the barrel 21 is brought to a temperature range below the liquid phase temperature and above the solid phase temperature. So that it can be cooled.

  In addition, in order to control the temperature of the molten metal MF in the barrel 21 with high accuracy, each temperature control jacket 24a of the cooling means 24 also has a heating function.

  Further, the screw hydraulic cylinder 27 is configured such that when it moves upward in the axial direction, a storage portion 23 having a volume larger than the volume of the molded product can be formed in the lower portion of the barrel 21. Furthermore, it has a sufficient stroke to move from the position where the storage portion 23 is formed to a position where the communication flow path 25 can be closed. The cylinder part 30 is connected via a communication channel 25 provided at the lower end of the barrel 21.

  The cylinder portion 30 is provided with a cylinder 31 having a nozzle portion 35 provided with a valve device 36 on the front side (downstream), and a plunger 32 that can move forward and backward along the axis of the cylinder 31 inside the cylinder 31. As the plunger 32 moves backward, the measuring portion 34 is formed in front of the cylinder 31, and when the plunger 32 moves forward, the semi-solid slurry HS is ejected from the nozzle portion 35. The volume of the measuring unit 34 can be appropriately set according to the retraction amount of the plunger 32 so as to have a capacity necessary for obtaining a molded product.

  The plunger hydraulic cylinder 37 is sufficient to move the communication flow path 25 connected to the vicinity of the tip of the cylinder 31 to a position where the plunger 31 can be closed when the plunger 32 moves forward from the position where the measuring portion 34 is formed. Has a good stroke.

  The plunger 32 is driven by the hydraulic pressure of the plunger hydraulic cylinder 37. The plunger hydraulic cylinder 37 is connected to a hydraulic control device 50 (not shown). Note that the valve device 36 provided in the vicinity of the nozzle portion 35 is in a closed state except during injection.

  The mold clamping unit 40 includes a link housing 42 erected on a base 41, a fixed plate 44 fixed to the link housing 42 via a horizontal tie bar 48, and fixed to the fixed plate 44. A fixed mold 61, a movable platen 45 slidably supported with respect to the tie bar 48, and a movable mold 62 fixed to the movable platen 45 so as to be openable and closable horizontally with respect to the fixed mold 61. And are provided.

  A mold clamping cylinder 46 is fixed to the center of the outer surface of the link housing 42, and the tip of the cylinder rod 47 of the mold clamping cylinder 46 is connected to the center of the movable platen 45. The link housing 42 and the movable platen 45 are connected by a plurality of links 43 that are folded when approaching and separated in a horizontal direction when separated.

  An extrusion cylinder 49 a is provided on the side surface of the movable platen 45 on the side of the link housing 42, and an extrusion rod 49 b of the extrusion cylinder 49 a passes through the movable platen 45 and is connected to a product protruding mechanism of the movable mold 62.

  Therefore, in the mold clamping unit 40, the cylinder rod 47 of the mold clamping cylinder 46 is protruded so that the plurality of links 43 extend in a straight line, and the plurality of links 43 are stretched. 62 can be strongly pressed against the fixed mold 61. Further, the release of the product is performed by operating the product projecting mechanism by projecting the push rod 49b of the push cylinder 49a.

  Next, the operation of the injection molding apparatus 100 and the light alloy injection molding method will be described.

  First, the molten metal MF is sent from the melting furnace 11 into the hopper 12. The molten metal MF is supplied to the supply port 28 of the barrel 21 in a gas-sealed state, and is cooled below the liquid phase temperature and above the solid phase temperature by each temperature control jacket 24a to grow into dendritic crystals. The dendritic crystals are agitated and crushed by the shearing action of the rotating screw 22 to generate uniform and fine crystal grains, and transition to the semi-solid slurry HS.

  In this case, the plunger 32 of the plunger injection device 33 has advanced to a position where the communication channel 25 is closed. Then, when the screw 22 of the screw extruder is retracted, a storage part 23 is formed between the screw 22 and the communication channel 25, and the semi-solid slurry HS is stored in the storage part 23.

  The screw 22 may be either one that stops rotating and moves backward, or one that moves backward while rotating. At this time, it is preferable to provide a backflow prevention means such as a check ring at the tip of the screw 22, and by providing the backflow prevention means, the molded product is allowed to smoothly flow the semi-solid slurry HS downward during retreat. Primary measurement is performed in the reservoir 23 having a volume larger than the volume.

  Next, the communication channel 25 is opened to retract the plunger 32, and at the same time, the screw 22 is advanced. Then, while the plunger 32 moves backward until it reaches a predetermined position set in accordance with the volume of the molded product, the semi-solid slurry HS is applied to the measuring unit 34 formed in front of the cylinder 31 while applying the pressure applied by the screw 22. Secondary weighing is performed by press-fitting while applying positive pressure.

  When the metering by press-fitting is completed, the communication channel 25 is closed by the screw 22, and the backflow of the semi-solid slurry HS from the metering unit 34 is prevented. During measurement, the nozzle portion 35 at the tip of the cylinder 31 of the plunger injection device 33 is closed by a valve device 36.

  In this way, after the secondary metering is completed, the valve device 36 of the nozzle portion 35 is opened and the plunger 32 is advanced to inject the semi-solid slurry HS into the mold 60 (see FIG. 1) to form a fixed-shaped molded body. Is formed.

  Next, details of the molding material charging unit 10 will be described. FIG. 2 is a schematic cross-sectional view for explaining the details of the molding material charging unit 10 shown in FIG. As shown in FIG. 1, the molding material charging unit 10 mainly includes a melting furnace 11 and a hopper 12.

  The melting furnace 11 includes a crucible 110, an opening / closing lid 111 and a heating device 112, and the hopper 12 includes a funnel-shaped container 120, a lid housing 121 and a heat retaining device 122. The heating device 112 is composed of an electric furnace, a high frequency induction furnace, an electromagnetic induction heating furnace or the like regardless of the type. The heat retaining device 120 is composed of temperature control means such as a heater regardless of the type.

  An open / close lid 111 is provided on the upper portion of the crucible 110 of the melting furnace 11, and a heating device 112 is provided around the crucible 110.

  In addition, a lid 121 is provided on the top of the funnel-shaped container 120 of the hopper 12, and a heat retaining device 122 is provided around the funnel-shaped container 120.

  As shown in FIG. 2, the melting furnace 11 and the hopper 12 are arranged at substantially the same height. One end of the pipe 130 is connected below the crucible 110, and the other end of the pipe 130 is connected below the funnel-shaped container 120. The pipe 130 is provided at a position lower than the liquid level height of the molten metal MF in the crucible 110 and the funnel-shaped container 120.

  In addition, one end of the pipe 140 is connected below the funnel-shaped container 120, and the other end of the pipe 140 is connected to the supply port 28 of the barrel 21. The pipe 140 is provided at a position lower than the connection position of the pipe 130. When the inner bottom portion of the melting furnace is located higher than the inner bottom portion of the hopper 12, the connection position of the pipe 130 to the melting furnace may be provided so as to face the inner bottom portion of the melting furnace.

  A screw 22 is provided inside the barrel 21, and the molten metal MF supplied from the supply port 28 is filled around the screw 22. A seal member 290 is provided above the barrel 21.

  An inert gas (for example, argon (Ar) gas or nitrogen (H) gas) is filled into the melting furnace 11, the hopper 12, and the barrel 21 by the gas supply device 150. As a result, the molten metal MF in the crucible 110, the funnel-shaped container 120 and the barrel 21 is sealed with an inert gas so that the molten metal MF does not come into contact with air (oxygen). Can be prevented.

  As shown in FIG. 2, the molten metal MF in the barrel 21 is filled to the same height as the liquid level of the melting furnace 11 and the hopper 12 according to the Pascal principle. Hereinafter, this filling will be described.

  FIG. 3 is a schematic diagram showing the movement of the molding material charging unit 10 shown in FIG. 3A, 3 </ b> B, and 3 </ b> C sequentially show the movement of the molding material charging unit 10.

  First, as shown in FIG. 3A, the opening / closing lid 111 of the melting furnace 11 is opened and a metal ingot 500 is charged. Thereafter, the open / close lid 111 is closed. The ingot 500 is melted by the action of the heating device 112 while suppressing oxidation of the molten metal surface with the inert gas supplied from the gas supply device. Thereby, the amount of the molten metal MF in the crucible 110 increases and the liquid level rises.

  In this embodiment, the opening / closing lid 111 is manually opened and the metal ingot 500 is inserted. However, the present invention is not limited to this, and the liquid level of the hopper 12 is detected and automatically melted. A device for charging the ingot 500 into the furnace 11 may be provided.

  Next, as shown in FIG. 3B, the molten metal MF in the crucible 110 flows through the pipe 130 in the direction of the arrow R1 and flows into the funnel-shaped container 120. That is, the molten metal MF moves according to the Pascal principle. And the quantity of the molten metal MF in the funnel-shaped container 120 increases. In this case, the molten metal MF is kept at a uniform temperature by the action of the heater 122 provided around the funnel-shaped container 120.

  Subsequently, as shown in FIG. 3C, the molten metal MF in the funnel-shaped container 120 is supplied to the barrel 21 via the pipe 140 and the supply port 28 in the direction of the arrow R2.

  As described above, in the injection molding apparatus 100 according to the present invention, the ingot 500 is melted by the crucible 11 to produce the molten metal MF, the molten metal MF produced by the crucible 11 is held by the hopper 12, and the crucible 11 And the hopper 12 is provided so that the liquid level is substantially equal, even if the amount of the molten metal MF in the crucible 11 increases due to melting of the ingot 500 charged into the crucible 11, the Pascal principle The liquid level in the hopper 12 is raised, and the liquid levels are almost equal to each other. As a result, a conventionally used device such as a pump becomes unnecessary, and the configuration of the injection molding device 100 can be simplified. In addition, since the pipe 130 that connects the crucible 11 and the hopper 12 is provided below the liquid surface height of the molten metal MF, impurities floating on the liquid surface of the molten metal MF of the crucible 11 do not move to the hopper 12 side. In addition, the pipe 140 communicated with the supply port 28 of the barrel unit 20 provided downstream is provided further below the pipe 130. As a result, more impurities are not transferred to the barrel 21. Accordingly, it is possible to prevent impurities and the like from being mixed into the molten metal MF in the hopper 12 and to prevent impurities from being mixed into the molten metal MF in the barrel 21. As a result, it is possible to prevent the occurrence of defective molded products molded by the injection molding apparatus 100.

  In addition, the crucible has the heating device 112 capable of melting the ingot 500 and includes the opening / closing lid 111 into which the ingot 500 can be charged, so that the ingot can be easily melted. Airtightness can be maintained except at the time of charging. In the present embodiment, the ingot is thrown into the crucible. However, the present invention is not limited to this, and another form of metal such as a metal tip may be thrown.

  Furthermore, the molten metal MF can be maintained in an optimum state by the heat retaining device 122 capable of maintaining the hopper 12 and the molten metal MF.

  Moreover, since the molten metal surface MF can be sealed by removing the air in the crucible 11, the hopper 12 and the barrel 21 by the gas supply device 150 and filling the inert gas, the oxidation of the molten metal MF can be prevented. . This gas supply device may be provided as a single device for the crucible, the hopper, or the barrel, or may be provided separately. However, when providing separately, it is necessary to set each supply pressure amount in the range which does not have a bad influence in the direction which a molten metal flows down. In the present embodiment, although not shown, a stirring device that stirs the molten metal MF in the hopper 12 may be provided to provide a stirring action if necessary.

  In the one embodiment, the molten metal MF corresponds to the molten metal, the injection molding apparatus 100 corresponds to the injection molding apparatus, the ingot 500 corresponds to the metal, the melting furnace 11 and the crucible 110 correspond to the crucible, The hopper 12 and the funnel-shaped container 120 correspond to the hopper, the pipe 130 corresponds to the pipe connecting the crucible 11 and the hopper 12, the supply port 28 corresponds to the supply port, the screw 22 corresponds to the screw, the barrel portion 20 corresponds to the barrel part, the pipe 140 corresponds to the supply pipe connected to the supply port of the barrel part, the opening / closing lid 111 corresponds to the opening / closing lid, the heating device 112 corresponds to the heating device, and the heat retaining device 122 It corresponds to a heat retaining device, argon gas or nitrogen gas corresponds to an inert gas, and the gas supply device 150 corresponds to a gas supply device.

  Although the present invention has been described in the above-described preferred embodiment, the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

The schematic diagram which shows an example of the injection molding apparatus of one Embodiment which concerns on this invention Typical sectional drawing for demonstrating the detail of the molding material injection | throwing-in part shown in FIG. Schematic diagram showing the movement of the molding material input part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Melting furnace 12 Hopper 28 Supply port 22 Screw 20 Barrel part 100 Injection molding apparatus 110 Crucible 111 Opening and closing lid 112 Heating apparatus 120 Funnel-shaped container 122 Heat retention apparatus 130 Piping 140 Piping 150 Gas supply apparatus 500 Ingot MF Metal melt

Claims (8)

An injection molding apparatus for injecting a molten metal at a predetermined pressure into a mold,
A crucible for melting the metal to produce the molten metal;
A hopper for holding the molten metal melted by the crucible;
And connecting the crucible and the hopper, and pipes provided so as to communicate below the liquid surface height of the molten metal of the crucible and the hopper, respectively.
An injection molding apparatus, wherein the crucible and the hopper are provided so that a liquid level height of the molten metal in the crucible is substantially equal to a liquid level height of the molten metal in the hopper. Further comprising a barrel portion provided with a screw for moving the molten metal supplied from the supply port in the interior, and provided with a supply port of the molten metal at the top,
The hopper
2. The injection molding apparatus according to claim 1, further comprising a supply pipe that is provided to discharge the molten metal below the pipe and that communicates with a supply port of the barrel portion. The crucible is
The injection molding apparatus according to claim 1, further comprising an opening / closing lid capable of charging the metal. The hopper
The injection molding apparatus according to claim 1, further comprising a heat retaining device capable of maintaining the molten metal. The crucible is
The injection molding apparatus according to any one of claims 1 to 4, further comprising a gas supply device capable of being sealed and capable of supplying an inert gas into the crucible. The hopper
The injection molding apparatus according to any one of claims 1 to 5, further comprising a gas supply device capable of being sealed and capable of supplying an inert gas into the hopper. A liquid level detection device for detecting a liquid level in the crucible and / or a liquid level in the hopper;
The injection molding apparatus according to any one of claims 1 to 6, further comprising a charging device that automatically charges the metal into the crucible based on a signal from the liquid level detection device. The barrel portion is
The injection molding apparatus according to claim 1, further comprising an airtight seal portion at a position higher than the liquid level in the crucible and the hopper.

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