JP2003320448A - Method and device for metal injection holding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for metal injection molding of a simple structure and reduced cost, by which a material ingot not restricted by the surface shape can be rapidly molten and even a metal molded article of high quality without containing bubbles and a complicated structure can be obtained. <P>SOLUTION: The device for metal injection molding comprises a melting part 1 for melting the material ingot M which is preheated to a melting starting temperature or lower and an injection part 20 for measuring and injecting the molten material K molten by the melting part 1. The melting part 1 is provided with a heating cylinder 2 which has a contraction part contracted in the inner diameter in the lower part while being in a hollow state capable of receiving the material ingot M preheated to the melting starting temperature or lower, an extruding piston 5 which reciprocates in a freely movable manner on the heating cylinder 2 and extrudes the material ingot M downward, and a heating device 10 which is provided on the outer periphery of the heating cylinder 2 and melts the material ingot M plastically deformed after passing through the contracting part 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal injection molding method and apparatus for injection molding a metal material such as an aluminum alloy or a magnesium alloy.

[0002]

2. Description of the Related Art In a molding machine for a metal material such as an aluminum alloy or a magnesium alloy, the metal shown in FIG. 3 is used for directly supplying the ingot to a heating cylinder without forming the material chip into a granular shape by mechanically processing the ingot. A raw material supply device for a molding machine is known (Japanese Patent Laid-Open No. 2001-30059). In the raw material supply device 102 of such a metal forming machine, a tubular body 105 communicating with the heating barrel and the tubular body 10 are provided.
5, a sealing member 106 that is provided on the inner wall surface of the raw material ingot 103 and contacts the outer peripheral portion of the raw material ingot 103 to block the inside of the tubular body 105 from the outside air; and a tip portion 103a of the raw material ingot 103 provided on the outer circumferential portion of the tubular body 105. It is provided with induction heating means 107 such as a high frequency that partially melts only the molten metal 108, and is configured to continuously supply the molten metal 108 melted in the tubular body 105 to the heating cylinder 104. A screw 110, which is a stirring and moving means, is rotatably provided in the heating cylinder 104. When the screw 110 is rotationally driven, the molten metal 108 supplied from the cylindrical body 105 is conveyed, and the tip portion 104 b of the heating cylinder 104 is conveyed. The semi-molten metal 109 is pressed into a mold (not shown) to obtain a desired metal molded product.

[0003]

SUMMARY OF THE INVENTION In the above conventional method,
There are the following problems.

In the raw material supply device of the metal forming machine described above, the metal material is supplied as an ingot, so that the material cost does not increase unlike the method of supplying the material chips.
However, since the sealing member provided on the inner wall surface of the cylindrical body and in contact with the outer peripheral portion of the material ingot blocks the cylindrical body from the outside air, the outer peripheral surface of the material ingot needs to be relatively smooth. However, there is a problem that the surface properties of the material ingot are restricted. Further, since it is necessary to use a seal member inside the tubular body, there is a problem that the cost of the metal forming machine itself increases.

Further, the screw is rotatably driven to convey the molten metal supplied from the cylindrical body, and the semi-molten metal is press-fitted into the mold from the tip of the heating cylinder to obtain a desired metal molded product.
Since the molten material solidifies quickly in the mold, it is necessary to fill the mold in a short time, and it is difficult to press it into the mold only by the rotational driving pressure of the screw, and it is a metal molded product with excellent surface properties. There is a problem that it is not possible to obtain a metal-molded product having a complicated shape having a small portion or a small portion.

[0006] The present invention is to solve the problems of the conventional apparatus as described above, the material ingot which is not restricted by the surface shape can be rapidly melted, high quality without containing bubbles, It is an object of the present invention to provide a metal injection molding method and apparatus that can obtain a metal molded product having a complicated structure and that has a simple structure and is inexpensive.

[0007]

In the invention according to claim 1 of the present invention, a melting portion (1) for melting a material ingot (M) preheated to a melting start temperature or less, and a melting portion (1) It consists of an injection part (20) for measuring and injecting the melted molten material (K), and the melting part (1) is a hollow shape capable of accommodating a material ingot (M) preheated below the melting start temperature, A heating cylinder (2) provided with a narrowed portion (4) having a reduced inner diameter therebelow, and an extruding piston (5) that is reciprocally movable in the longitudinal direction of the heating cylinder (2) and pushes the material ingot downward. And a heating device (10) provided on the outer peripheral portion of the heating cylinder (2) for melting the plastically deformed material that has passed through the narrowed portion (4).
The plastically deformed material ingot (M) blocks contact between the molten metal and the outside air, improves heat transfer between the material ingot (M) and the inner surface of the heating cylinder (2), and rapidly melts the molten metal in the mold. It is characterized in that it is injected into.

According to a second aspect of the present invention, an induction heating device is used as the heating device (10) provided on the outer peripheral portion of the heating cylinder (2) according to the first aspect. . Therefore, compared to the case of using an electric heater,
The material ingot (M) can be melted more rapidly.

In the invention according to claim 3 of the present invention, the injection part (20) is connected so as to communicate in front of the throttle part (4) of the heating cylinder (2), and the other is communicated with the mold. The chamber (21) connected to the nozzle (25) and the chamber (2
1) A rod part (24) is reciprocally provided in the rod part (1), a backflow prevention device (26) is provided on the injection nozzle (25) side of the rod part (24), and an injection nozzle (25) of the rod part (24) is provided. ) And an injection piston (22) having a seal portion (23) for blocking the inside of the chamber (21) from the outside air.

According to a fourth aspect of the present invention, the injection piston (22) is provided with a position detector (35) for detecting the position of the injection piston (22).

The fifth aspect of the present invention is characterized in that an inert gas supply means (G) is provided behind the throttle portion (4) of the heating cylinder (2). The rear side of the throttle portion (4) means the throttle portion (4) from the side where the material ingot (M) is supplied in the heating cylinder (2).
Up to.

In the invention according to claim 6 of the present invention, the material ingot (M) preheated to the melting start temperature or lower is supplied to the heating cylinder (2) provided with the narrowed portion (4) having the reduced inner diameter. The material ingot (M) is extruded by an extruding piston (5) reciprocally provided in the heating cylinder (2) to plastically deform the material ingot (M).

In the invention according to claim 7 of the present invention, the throttle portion (4) is cut off in front of the throttle portion (4) from the outside air.
It is characterized in that the material ingot (M) that has passed through the position and is plastically deformed is rapidly melted. The front side of the throttle portion (4) means the side where the material ingot (M) is extruded from the throttle portion (4) in the heating cylinder (2) by the extrusion piston (5), that is, the injection portion (20).
It refers to the side connecting to.

In the invention according to claim 8 of the present invention, an injection piston in which a molten material is supplied into a chamber (21) communicating with the heating cylinder (2) and the chamber (21) is reciprocally movable. (22) is characterized in that the molten metal is injected into the mold.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an essential part of a metal injection molding apparatus showing an embodiment of the present invention. As shown in FIG. 1, the metal injection molding apparatus according to the present embodiment mainly melts a cylindrical material ingot M that has been preheated to a temperature below the melting start temperature, and a melting section 1 that melts the material ingot M. It comprises an injection unit 20 for measuring and injecting the molten material K.

The melting part 1 has a cylindrical hollow inside, and a heating cylinder 2 in which a narrowed part 4 having a reduced inner diameter is provided in the middle.
Is equipped with. Behind the heating cylinder 2, a material ingot M
The material supply port 3 for supplying the metal is opened.

The surface texture of the material ingot M may be somewhat rougher than that of the conventional one. That is, the material ingot M may be slightly smaller than the inner diameter of the heating cylinder 2 as long as the material ingot M can be accommodated in the heating cylinder 2 and has an outer diameter larger than that of the narrowed portion 4. Further, it is preferable that the material ingot M has a melting start temperature or lower and a maximum temperature at which the material ingot M does not deform during handling. This is because if the temperature is too high, it easily oxidizes and cannot be handled. On the contrary, if the temperature of the material ingot is too low, a huge extrusion force is required at the time of extrusion. As a specific example, magnesium alloy A
In the case of M50A, since the melting start temperature is 540 ° C,
Set to about 500 ° C.

The material ingot M is conveyed to the material supply port 3 of the heating cylinder 2 from a heat insulation furnace (not shown). For example, this conveying means may be provided with a passage between the heat-retaining furnace and the material supply port 3, and the material ingot M may be dropped from the heat-retaining furnace into the heating cylinder 2 by an air cylinder or the like. In this case, since the material ingot M is simply dropped, a great force does not act.

Since there is a possibility that air will be mixed in above the throttle portion 4, an inert gas such as argon gas is supplied from the gas cylinder G to the material supply port 3. Inside the heating cylinder 2, there is provided an extruding piston 5 which is reciprocally movable between the narrowed portion 4 and the rear of the material supply port 3. The pushing piston 5 pushes the material ingot M forward of the heating cylinder 2 and plastically deforms it in the narrowed portion 4. An induction heating device 10 is provided on the outer peripheral portion of the heating cylinder 2 in front of the throttle portion 4.

The degree of throttling of the throttle portion 4 of the heating cylinder 2 is about 1: 1.1 in terms of the sectional area ratio between the throttle portion 4 and the heating cylinder 2.
It is about 1.5. It suffices if the material ingot M can be deformed to block the open air from the molten material. This is because the larger the drawing ratio, the larger the pushing force required, and therefore the smaller the drawing ratio is desirable. In addition, the diaphragm unit 4
The larger the tilting angle of, that is, the angle of the tilted surface with respect to the extrusion direction (maximum 90 °), the larger the pushing force is required.
It is preferably in the range of 3 to 60 °.

The pressing force of the extrusion piston 5 against the material ingot M is considered to be about 100 to 150 MPa at the contact surface between the extrusion piston and the material ingot.
If the heating cylinder inner diameter cross-sectional area is added to this value, the extrusion pressure will be obtained, and the extrusion force will vary depending on the model of the injection molding machine, but the extrusion surface pressure will be the above value. The drive of the pushing piston 5 is
Use hydraulic cylinders. In the present embodiment, the pushing piston 5 is driven by a hydraulic cylinder, but the driving is not limited to this and may be a motor driving. Further, as a driving means of the pushing piston 5, as shown in FIG. 2, the material ingot M is sandwiched between the rolls 51 arranged on both sides and the rolls 51 on both sides are internally rotated to push the material ingot M forward. Method (a), by rotating the screw screw 53, the material ingot M
The driving method may be a method (b) of extruding the material in the forward direction or a method (c) of extruding the material ingot M by rotating the crank shaft by the crank mechanism 55.

In FIG. 1, the melting part 1 including the heating cylinder 2 is vertically arranged above the injection part 20 including the chamber 21, but the melting part 1 is arranged parallel or inclined upward and connected between the two. It is also possible to provide a section. The injection unit 20 includes a chamber 21 provided with a communication port 30 that communicates with the heating cylinder 2. An injection nozzle 25 communicating with a mold (not shown) is connected to the front of the chamber 21.
Inside the chamber 21, a seal portion 23 having an outer peripheral surface in contact with the inner peripheral surface of the chamber 21 is provided, and an injection piston 22 movable reciprocally is provided.

The injection piston 22 comprises a seal portion 23, a rod portion 24, and a backflow prevention device 26. The seal portion 23 has a cylindrical shape with an outer diameter slightly smaller than the inner diameter of the chamber 21. This is for the purpose of preventing leakage of the molten material to the outside and shutting off the outside air. The seal portion 23 is
It is desirable that it be detachable and replaceable because it may come into contact with the inner wall of the chamber 21 and wear.

The rod portion 24 has a cylindrical shape slightly smaller than the inner diameter of the chamber 21. Since it is necessary to secure a flow path leading to the front of the backflow prevention device 26 from the communication port 30,
It has such a shape. The molten material K passing through this portion is in a molten state, and it is not necessary to make the flow passage larger than necessary in terms of strength in design.

The seal portion 23 is located at the rear end of the chamber 21 when the rod portion 24 is most retracted, and the communication port 3 of the chamber 21 is at the most advanced position of the rod portion 24.
It is located at 0 rear. A backflow prevention device 26 is provided at the tip end portion of the rod portion 24. The backflow prevention device 26 secures a flow path of the molten material K from the rear side to the front side of the backflow prevention device 26, and the backflow prevention device 26 is provided. This is to prevent backflow from the front to the rear. Backflow prevention device 26
Is composed of a head 41, a backflow prevention ring 42, an oscilloscope 43 located at the tip of the rod portion 24, and a piston ring (not shown) provided on the outer periphery of the backflow prevention ring 42. Further, as an alternative means, if it is a 1-way check valve, there is no functional problem, and a ball check valve or the like may be used.

The injection piston 22 also includes a position detector 35 for detecting the position of the injection piston 22. The push-out piston 5 advances, and the chamber 21 comes out from the communication port 30.
In the step of supplying the molten material K to, the operation of the pushing piston 5 is controlled by the position of the injection piston 22 detected by the position detector 35.

Next, the molding operation using the metal injection molding apparatus of this embodiment will be described. First, the injection piston 22 is in the most advanced position because the injection has been completed. Although not shown, the extruding piston 5 is set to the most retracted position, and a cylindrical material ingot M that has been preheated to a temperature below the melting start temperature in advance in a heat insulation furnace or the like is supplied to the material supply port 3 of the heating cylinder 2. At this time, when the material ingot M is chemically active, for example, when it is a magnesium alloy, an inert gas is supplied from the gas cylinder G to prevent oxidation.

In the measuring step, the extrusion piston 5 is moved forward to extrude the supplied material ingot M in front of the heating cylinder 2. When the material ingot M reaches the narrowing portion 4,
Plastic deformation occurs, and the material ingot M blocks the molten material K in front of the narrowed portion 4 from the outside air. The metal material that has passed through the narrowed portion 4 is melted by the induction heating device 10 provided on the outer peripheral portion of the heating cylinder 2.

In the measuring step performed after the completion of the injection step, the solidified molded product is contained in the mold, and this serves as a plug to close the tip of the injection nozzle 25. For this reason,
By pushing the pushing piston 5 forward, pushing pressure is generated in the heating cylinder 2, and the pushing pressure causes the chamber 2 to move.
A force for retracting the injection piston 22 is generated within 1. Therefore, the molten material K is supplied into the chamber 21 while the injection piston 22 retracts. Since the injection piston 22 is retracted by the force generated by the pushing pressure and the molten material K is supplied from the heating cylinder 2 to the chamber 21, the chamber 21 is filled with the molten material K containing no bubbles. Further, since the seal portion 23 of the injection piston 22 blocks the outside air, the molten material K does not oxidize and the chamber 2 does not oxidize.
Held within 1.

When the position detector 35 detects that the injection piston 22 has reached a preset measurement completion position corresponding to the volume of the metal molded product, the extrusion piston 5 is stopped to complete the measurement. By advancing the injection piston 22 at a high speed, the molten material K measured in the chamber 21 is injected into the mold through the injection nozzle 25 in a short time,
A desired metal molded product can be obtained by cooling and solidifying.
When the injection piston 22 moves forward, the measured melted material K in front of the backflow prevention device 26 does not flow back to the back of the backflow prevention device 26, so that the measured melted material K can be reliably injected into the mold.

When a metal molded product is obtained as described above,
The material ingot M in the heating cylinder 2 decreases. The extruding piston 5 is set to the final retracted position again, and the cylindrical material ingot M preheated in advance in a heat-retaining furnace or the like to a temperature below the melting start temperature is additionally supplied to the heating cylinder 2, and the extruding piston 5 is moved forward to continuously. A desired metal molded product can be obtained.

[0032]

As described above, in the inventions according to claims 1 and 6 of the present invention, the melting portion is hollow so that the material ingot preheated to the melting start temperature or lower is supplied, and the inner diameter is formed below it. , A heating cylinder provided with a reduced diameter portion, an extruding piston that can reciprocate in the longitudinal direction of the heating cylinder and pushes the material ingot downward, and a heating cylinder that melts the plastically deformed material that has passed through the narrowing portion. Since it is configured to include a heating device provided on the outer peripheral portion of the material, the preheated material ingot is supplied to the heating cylinder and extruded by the extrusion piston, so that the material ingot is plastically deformed in the narrowed portion in the heating cylinder. However, the material ingot can block the molten material in front of the throttle from the outside air. In addition, since it is heated by the heating device in front of the throttle,
The effect that the material ingot can be rapidly melted in a state of being shielded from the outside air is obtained. In addition, since the material ingot blocks the molten material in front of the throttle from the outside air, there is no restriction on the surface properties of the material ingot, and there is no need to have a sealing portion as in the past. Therefore, the structure of the device is simple and inexpensive. Further, since the columnar material ingot is directly supplied to the heating cylinder, the material cost can be reduced.

According to the second aspect of the present invention, since the induction heating device is used for the heating device provided on the outer peripheral portion of the heating cylinder, the material ingot is compared with the case where an electric heater or the like is used. It can be melted more rapidly.

According to the third and eighth aspects of the present invention, the plastically deformed material in the throttle portion blocks the contact between the molten metal and the outside air to improve the heat transfer between the material and the inner surface of the heating cylinder. Since it is configured to inject molten metal rapidly melted into the mold, the injection piston is retracted by the force that retracts the piston generated by the extrusion pressure, and the molten material is supplied from the heating cylinder to the chamber. Can be filled with a bubble-free molten material. Further, since the seal part of the injection piston blocks the outside air, the molten material is held in the chamber without being oxidized, and the molten material in the chamber is injected into the mold by the injection piston in a short time, It is possible to obtain a metal molded product having excellent properties and a metal molded product having a complicated shape with details.

In the invention according to claim 4 of the present invention, the injection piston is provided with a position detector for detecting the position of the injection piston. Therefore, the injection piston is preset in accordance with the volume of the metal molded product. The position detector can detect that the measurement completion position has been reached.

In the invention according to claim 5 of the present invention, since the inert gas supply means is provided behind the throttle portion of the heating cylinder, air is prevented from entering.

In the invention according to claim 7 of the present invention, since the plastically deformed material passing through the throttle portion is melted in a state where the front of the throttle portion and the outside air are shielded, the material ingot is shielded from the outside air. In this state, the effect of being able to melt is obtained. In addition, since the material ingot blocks the molten material in front of the throttle from the outside air, there is no restriction on the surface properties of the material ingot, and there is no need to have a sealing portion as in the past. Therefore, the structure of the device is simple and inexpensive.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a metal injection molding apparatus showing an embodiment of the present invention.

FIG. 2 shows a method for driving a piston of a metal injection molding apparatus according to another embodiment of the present invention, in which (a) is a method of extruding a material ingot by sandwiching it between rollers and rotating the rollers internally. (B) is a method of pushing the material ingot forward by rotating a screw screw,
(C) shows a method of extruding a material ingot by rotating a crank shaft by a crank mechanism.

FIG. 3 is a front sectional view showing a part of a conventional metal forming machine.

[Explanation of symbols]

1 fusion zone 2 heating cylinder 3 Material supply port 4 throttle 5 Extrusion piston 10 heating device 20 injection part 21 chamber 22 injection piston 23 Seal part 24 Rod part 25 injection nozzle 26 Backflow prevention device 35 Position detector M material ingot K molten material G gas cylinder (inert gas supply means)

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22D 39/06 B22D 39/06 (72) Inventor Yasuhiko Sawada 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima-shi, Hiroshima Stock Company Japan Steel Works (72) Inventor Takeshi Yamaguchi 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima-shi, Hiroshima Prefecture F-terms in Japan Steel Works (reference) 4E014 LA18

Claims (8)

[Claims] 1. A melting section (1) for melting a material ingot (M) preheated to a melting start temperature or less, and an injection section for measuring and injecting the molten material (K) melted in this melting section (1). (20), and the melting part (1) is hollow so that the material ingot (M) preheated to a temperature below the melting start temperature can be accommodated therein, and a narrowed part (4) having a reduced inner diameter is provided below the melting part (1). A heating cylinder (2), an extruding piston (5) which is reciprocally movable in the longitudinal direction of the heating cylinder (2) and pushes out the material ingot downward, and a throttling portion provided on the outer peripheral portion of the heating cylinder (2). A heating device (10) for melting the plastically deformed material that has passed through (4) is provided, and the contact between the molten metal and the outside air is shut off by the plastically deformed material ingot (M) in the throttle portion (4). The material ingot (M) and the inner surface of the heating cylinder (2) Metal injection molding apparatus, characterized in that the molten metal was rapidly melted to improve the heat transfer and to be injected into the mold. 2. The metal injection molding apparatus according to claim 1, wherein the heating device (10) provided on the outer peripheral portion of the heating cylinder (2) is an induction heating device. 3. The chamber (21) connected to the injection part (20) in front of the throttle part (4) of the heating cylinder (2) so as to communicate therewith, and the other part to an injection nozzle (25) connected to the mold. )
The rod portion (24) is reciprocally provided in the chamber (21), and the backflow prevention device (26) is provided on the injection nozzle (25) side of the rod portion (24). The injection piston (22), which is provided on the opposite side of the injection nozzle (25) and has a seal portion (23) for blocking the inside of the chamber (21) from the outside air. 2. The metal injection molding device according to 2. 4. The metal injection molding apparatus according to claim 3, wherein the injection piston (22) is provided with a position detector (35) for detecting the position of the injection piston (22). 5. The metal injection according to claim 1, wherein an inert gas supply means (G) is provided behind the throttle portion (4) of the heating cylinder (2). Molding equipment. 6. A material ingot (M) preheated to a temperature below the melting start temperature is supplied to a heating cylinder (2) provided with a narrowed portion (4) having a reduced inner diameter, and reciprocated in the heating cylinder (2). A metal injection molding method, characterized in that a material ingot (M) is extruded by a freely provided extrusion piston (5) to plastically deform the material ingot (M). 7. The material ingot (M) which has been plastically deformed by passing through the throttle portion (4) in front of the throttle portion (4) while being shielded from the outside air, is rapidly melted. 6. The metal injection molding method according to 6. 8. A molten material is supplied into a chamber (21) communicating with the heating cylinder (2), and a molten metal is injected into a mold by an injection piston (22) reciprocally provided in the chamber (21). The metal injection molding method according to claim 6 or 7, characterized in that the metal injection molding is performed.