EP2821163A1

EP2821163A1 - Method for molding amorphous alloy, and molded object produced by said molding method

Info

Publication number: EP2821163A1
Application number: EP13755554.6A
Authority: EP
Inventors: Takashi Hashima; Yoichi Inoue; Yasunori Saotome; Kenji Amiya
Original assignee: Heishin Techno Werke Ltd; Tohoku University NUC
Current assignee: Heishin Techno Werke Ltd; Tohoku University NUC
Priority date: 2012-02-29
Filing date: 2013-01-30
Publication date: 2015-01-07
Also published as: KR20140131366A; CN104302424B; JP6417079B2; CN104302424A; JP2013176791A; US20150202684A1; WO2013129012A1; EP2821163A4

Abstract

Provided are a method of molding an amorphous alloy, which has a high degree of work freedom regardless of components of an amorphous alloy, in particular, metallic glass and of the shape of an article to be molded, and is capable of producing a molded article having less pores, and a molded obj ect produced by the molding method. The method of molding an amorphous alloy includes: a melting step of melting an amorphous alloy; a differential-pressure casting step of injecting a melt of the amorphous alloy into a casting mold positioned below the melt and evacuating the casting mold; and a processing step of processing the melt by heating and pressurizing the melt in the casting mold while keeping the melt in a supercooled state.

Description

Technical Field

The present invention relates to a method of molding an amorphous alloy that is excellent in quality and has a high degree of shape freedom, and to a molded object produced by the molding method. Specifically, the present invention relates to a molding method capable of processing metallic glass while keeping a supercooled state in a casting mold, and to a molded article, such as a rotor of a uniaxial eccentric screw pump, produced by the molding method.

Background Art

In general, metallic glass that is a kind of an amorphous alloy has specific mechanical property that is not inherent in general metals. Specifically, the metallic glass has a low Young' s modulus (flexibility) while keeping the mechanical strength due to its high strength and high hardness. Therefore, the metallic glass has been expected to be utilized for various materials, and the application thereof to a bar-shaped member having a small diameter, such as a rotor of a uniaxial eccentric screw pump described later, has been expected.
Hitherto, a method of molding an amorphous alloy involves casting a melt into a water-cooled mold. For example, in Patent Literature 1 ( JP 2002-224249 A ), an alloy material of an amorphous alloy member is melted by heating with a high-frequency induction heating coil, and the melt is cast into a water-cooled casting mold and quenched in the mold.
However, the casting into the casting mold in Patent Literature 1 merely involves pouring the melt into the casting mold, thereby causing the following problems. Specifically, surrounding atmospheric gas is liable to be drawn in, the melt is solidified due to quenching before the drawn-in gas and occluded gas that has occluded the surrounding atmospheric gas during melting are released, and those gases are confined in metallic glass to form pores having various sizes. The pores refer to void parts such as micropores present in a material for the metallic glass and cause significant decrease in mechanical strength of the material in a cast molded object.
Further, for example, Patent Literature 2 ( JP 2006-175508 A ) discloses a method of molding an amorphous alloy, which involves melting an amorphous alloy, pouring the melt into a casting mold, pressurizing the melt in the casting mold by pressing, and quenching the melt. This molding method has the following advantage. Specifically, the melt in the casting mold is pressurized by pressing and quenched, and hence gas in the melt that causes pores is forcibly discharged to reduce inner pores.
However, the method of molding an amorphous alloy of Patent Literature 2 has the following drawback. Specifically, the method adopts the steps of pouring the melt into the casting mold, pressurizing the melt to eliminate the pores, and quenching the melt. Thus, the melt is annealed and crystallized while being poured into the casting mold when a small molded article is produced, with the result that an amorphous alloy is not formed in some cases. Accordingly, the shape and size of an article to be molded depend on the material for and the amount of the melt, and a molded article has a small degree of work freedom.

Citation List

Patent Literature

[PTL 1] JP 2002-224249 A
[PTL 2] JP 2006-175508 A

Summary of Invention

Technical Problems

The present invention has been made so as to solve the above-mentioned problems, and it is an obj ect of the present invention to provide a method of molding an amorphous alloy, which has a high degree of work freedom regardless of components of an amorphous alloy, in particular, metallic glass and of the shape of an article to be molded, and is capable of producing a molded article having less pores, and to provide a molded object produced by the molding method.

Solution to Problems

According to one embodiment of the present invention, there is provided a method of molding an amorphous alloy, including: a melting step of melting an alloy; a differential-pressure casting step of injecting a melt of the alloy into a casting mold positioned below the melt and evacuating the casting mold; and a processing step of processing the melt by pressurizing a casting metal in the casting mold under a high-temperature state while keeping the melt in a supercooled state.
According to one embodiment of the present invention, when the amorphous alloy is molded, the melt is filled into a small casting mold rapidly by evacuating the casting mold while the melt is poured into the casting mold, and pores and the like formed in this case are reduced by pressurizing the melt. At this time, the melt can be filled into the casting mold sufficiently in a temperature region falling within a temperature range (supercooling temperature range) that corresponds to an intermediate temperature lower than a crystallization temperature of the metal and higher than a glass transitiontemperatureofthe metal. Thus, a molded article required to have a small shape or a larger longitudinal length ratio, or to have high fluidity in the melt in the casting mold can be provided with less pores.
In particular, the "amorphous alloy" as used herein is preferably metallic glass.
The metallic glass is a kind of an amorphous alloy and is a metal in which glass transition can be observed clearly. In the present invention, the metallic glass is processed in a state of a supercooled fluid. That is, the metallic glass is processed in a time region in which the formation of a crystal phase does not occur even when the metal temperature decreases, and thereafter, the metallic glass is strongly pressurized with the temperature being kept in the casting mold while the fluidity of the metallic glass ismonitored. Withthis, a metallic glass molded article having a shape without defects in which pores are crushed can be produced in a bulk shape. Accordingly, the effect of mass productivity of molded articles can be expected by optimizing the conditions of the processing step, and cost can be reduced.
Further, the casting metal is heated in the processing step by causing a high-frequency current to flow through a coil provided on a periphery of the casting mold.
The casting metal is heated, for example, by causing the high-frequency current to flow through the coil wound around the periphery of the casting mold to conduct heat from the outside to the inside of the casting mold (high-frequency induction heating) . This method is advantageous in that the temperature of the melt can be controlled by regulating a coil current, and the temperature can be controlled easily in accordance with a change in the melt and the external atmosphere.
Alternatively, the casting metal may be heated by irradiating the casting mold with infrared light or may be heated through use of radiation heat obtained by irradiating the casting mold with infrared light.
On the other hand, such a method is conceived that the melt is pressurized in the processing step by pressurizing the melt with gas through a hole formed in the casting mold.
The melt can be pressurized uniformly without preparing a mechanical pressurizing device separately as long as gas inflow means to an inlet hole and an output hole of the casting mold, for pressurizing the melt with gas, and air tightness are ensured.
Alternatively, such a method is adopted that the melt is pressurized in the processing step by pressurizing the melt with an actuator through a hole formed in the casting mold.
It is advantageous to pressurize the melt with the actuator in that there is no response lag caused by the compression and the like of gas as in gas pressurization because the melt is pressurized directly and mechanically.
A molded article produced by the above-mentioned method of molding an amorphous alloy can be produced in a bulk shape even from the metallic glass with high accuracy. Thus, even a minute rotor of a uniaxial eccentric screw pump having a shape with a larger longitudinal length ratio can be produced with high mechanical strength and repetition fatigue strength simply by optimizing heating and processing conditions.

Advantageous Effects of Invention

According to one embodiment of the present invention, shaping can be performed while the pores and the like are reduced by pressurizing the melt and the supercooled state is kept in the casting mold, and hence a molded article of an amorphous alloy having various shapes, sizes, and components can be provided easily.

Brief Description of Drawings

FIG. 1(a) shows a specific heat curve of an amorphous alloy, and FIG. 1(b) shows a specific heat curve of metallic glass.
FIG. 2 is a transformation diagram of a related-art amorphous alloy and metallic glass.
FIGS. 3 are schematic views illustrating a molding step for a rotor 1 of a uniaxial eccentric screw pump made of metallic glass in time series.
FIG. 4 is a flowchart of the schematic view of FIGS. 3.
FIG. 5 describes, while referring to, a specific heat curve of a melt of metallic glass in a casting mold in a processing step (viscous flow processing step) in a method of molding an amorphous alloy of the present invention.
FIG. 6 is a partial side view schematically illustrating a state of a molding device for performing the molding method of the present invention, when viewed from a lateral side.
FIG. 7 (a) is an enlarged horizontal sectional view of a casting mold in the molding device of FIG. 6, FIG. 7 (b) is an enlarged plan view of an injection port in the vicinity of a right end when viewed from above, and FIG. 7(c) is a side view of FIG. 7(a).
FIG. 8 is a view illustrating a uniaxial eccentric screw pump.

Description of Embodiments

First, an amorphous alloy, in particular, metallic glass to be molded in a method of molding an amorphous alloy of the present invention is described.
General metals and alloys have a crystal structure in which atoms are arranged periodically. When melted by heating, the metals and alloys become a liquid to have a structure in which the atoms are packed densely at random. The state not having a periodic structure is called an amorphous state. In general, when the liquid is solidified, the liquid changes to a crystal. However, predetermined alloys form a solid while keeping an amorphous structure when quenched. Such an alloy is called an amorphous alloy. Of the amorphous alloys, an alloy exhibiting glass transition that is one of the features of glass is called metallic glass.
FIG. 1(a) shows a specific heat curve of an amorphous alloy, and FIG. 1(b) shows a specific heat curve of metallic glass. As seen in the specific heat curve of FIG. 1(a), in general, the amorphous alloy reaches a crystallization temperature by heating before reaching a glass transition point T_g and the crystallization thereof proceeds. Thus, no glass transition is observed. On the other hand, as shown in FIG. 1(b), in the case of an amorphous alloy having a resistance to crystallization, which is stable in a supercooled liquid state, that is, stable in an amorphous structure, the amorphous alloy reaches the glass transition point T_g prior to a crystallization temperature T_x due to an increase in temperature, and the crystallization thereof proceeds when the temperature becomes higher than the glass transition point T_g. The amorphous alloy having the glass transition point T_g lower than the crystallization temperature T_x is called metallic glass, and the general amorphous alloy (T_x<T_g) and the metallic glass (T_x>T_g) are discriminated from each other.
Next, the difference between the amorphous alloy and the metallic glass is described with reference to a transformation diagram therebetween of FIG. 2.
The dotted line (a) on a left side represents a general amorphous alloy. The general metal is solidified at a melting point T_m or less, and the crystallization thereof proceeds and the work hardening thereof also increases at the glass transition temperature T_g or less unless the metal is further quenched. On the other hand, the dotted line (b) on a right side represents metallic glass. The supercooled region of the metallic glass is still large even at the melting point T_m or less and can be molded to a bulk product having a thickness to some degree even over a long period of time.
Next, a basic configuration of the method of molding an amorphous alloy of the present invention is described.
In the molding method described above, a melt of metallic glass is injected into a casting mold, and the melt is processed by heating and pressurizing the melt in the casting mold while being kept in a supercooled state. Herein, description is made of an exemplary case where a rotor of a uniaxial eccentric screw pump made of metallic glass is an article to be molded by the molding method. Note that, the uniaxial eccentric screw pump and the use example thereof are described later.
FIGS. 3 are schematic views illustrating a molding step for a rotor 1 of a uniaxial eccentric screw pump made of metallic glass in time series. FIG. 4 is a flowchart thereof (specific device configuration example is described later). As a basic material of a metallic glass material as illustrated in FIG. 3(a), a columnar standard rod 2 is used. The standard rod 2 is produced by performing selection and blending of an alloy in consideration of mechanical physical properties. Herein, a Pd-based alloy excellent in castability, a low-cost Ni-based alloy excellent in mass productivity, and the like are considered as candidate materials for the rotor 1. The standard rod 2 is split in an axial direction as illustrated in FIG. 3(b), and pellets 3 each corresponding to the amount of one rotor 1 are stacked and stored. Then, the pellet 3 is heated to generate a melt of metallic glass (see STEP 1 of FIG. 4 (hereinafter only STEP No. is described)).
Next, the process proceeds to a step of injecting a melt 7 of metallic glass into a casting mold 4 (STEP 2). The step is herein referred to as a differential-pressure casting step, in which the melt 7 pressurized with gas is injected into the casting mold 4 through an inlet on a left end of the drawing sheet of FIG. 3(c) (STEP 3), and the casting mold 4 is evacuated with a vacuum pump (described later) through an outlet on a right end of the drawing sheet of FIG. 3(c) (STEP 4). Although the melt 7 is injected into the casting mold 4 through the inlet on the left end in a gap between an upper die 4-1 and a lower die 4-2 in FIG. 3 (c), it is also considered to form an injection port 4a in an upper part of the casting mold 4 as illustrated in FIG. 6 and to inject the melt 7 into the casting mold 4 through the injection port 4a. There is an advantage in that, when the differential-pressure casting step is performed, the melt 7 is sufficiently filled into the casting mold 4 even in the case where an article to be molded has a thin shape at a larger longitudinal length ratio as in the rotor 1. On the other hand, a great number of pores and the like are formed in the melt 7. If the melt 7 is cooled to produce a molded article while a great number of pores are formed, the mechanical strength of the molded article cannot be ensured sufficiently. In order to reduce the pores, the molding method of the present invention additionally includes a viscous flow processing step illustrated in FIG. 3(d) (STEP 5).
As illustrated in FIG. 3(d), in the viscous flow processing step (STEP 5), the melt 7 in the casting mold 4 is heated and pressurized. That is, in the viscous flow processing step, high-temperature control (STEP 6) and pressurizing treatment (STEP 7) are performed simultaneously in the casting mold 4. In the pressurizing treatment, the inlet port and the outlet port of the casting mold 4 are pressurized from both sides as indicated by the arrows F, and in the high-temperature control, the casting mold 4 is heated by supplying a high-frequency coil current from an AC power source to a coil 5 wound around the periphery of the casting mold 4. In the case of high-frequency heating, the melt 7 in the casting mold 4 is heated from an outer surface of the casting mold 4 by heat conduction, and for example, PID control is adopted as the temperature control. Although the high-frequency heating is preferred as the high-temperature control (STEP 6) because deviation between the coil current and the increase/decrease in temperature is small, it is also considered to use infrared light or radiation heat. Further, the pressurizing treatment (STEP 7) is advantageous in that a method of applying a pressure with inert gas can be provided with a simple configuration. Alternatively, a method of directly pressurizing the inlet port and the outlet port of the casting mold 4 through use of an actuator is also considered as the pressurizing treatment.
The processing process of the melt 7 in the casting mold 4 in the viscous flow processing is described with reference to a specific heat curve of FIG. 5. Herein, the case of using a metallic glass Pd alloy as a material for the molded article (rotor 1) is described.
The viscous flow processing encompasses processing in a state of a supercooled fluid and refers to processing at a temperature of from the melting point T_m to the glass transition point Tg. The metallic glass Pd alloy is processed in a time region in which the formation of a crystal phase does not occur even when the metal temperature of the Pd alloy decreases. When the metallic glass Pd alloy is then strongly pressurized with the temperature in the casting mold 4 being kept while the fluidity thereof is monitored, pores are crushed and the number thereof is reduced significantly, with the result that a shape without defects can be obtained. In FIG. 5, a Pd alloy having a melting point T_m of 400°C is used and pressurized while the viscous fluidity is kept so that the cooling rate has a rate gradient of about 1°C/sec or more in a temperature region of from the crystallization temperature T_x of 380°C to the glass transition point T_g of 350°C after the casting. Accordingly, an amorphous metallic glass is formed. The mass productivity effect of a molded article can be expected and cost can be reduced by setting the optimum conditions of the viscous flow processing.
The description is made with reference to FIGS. 3 again. After the viscous flow processing is performed in FIG. 3(d), the supercooled state is finished by cooling the melt 7, and the melt 7 is solidified (STEP 8). Although not shown, the cooling treatment is generally performed by cooling the casting mold 4 that contains the melt 7 to the glass transition point Tg or less with water (detailed example is described later). For example, as described above with reference to FIG. 5, the Pd alloy is quenched to 350°C or less. After that, the casting mold 4 is separated (split) into the upper die 4-1 and the lower die 4-2, and the solidified metallic glass 7 is ejected from the casting mold 4 (STEP 9).
In the metallic glass ejected from the casting mold 4, in general, the rotor 1 being a molded article has parting lines formed therein. Therefore, rolling finish is performed as illustrated in FIG. 3 (e) (STEP 10). The rolling finish is performed with a rolling die 6 so as to enhance the dimensional accuracy, and herein, description is made of an exemplary case where the rotor 1 is held while an upper rolling die 6a and a lower rolling die 6b each having a shape conforming with the shape of the rotor 1 are axially rotated. Further, the rolling die 6 may perform rolling by causing two rotating round dies to hold the rotor 1. Then, the surface of the rotor 1 subjected to rolling finish as illustrated in FIG. 3(f) is finally polished by electrolytic polishing or the like (STEP 11). In this manner, the rotor 1 is completed.
Next, FIGS. 6 to 7 illustrate a specific configuration example of a molding device for metallic glass, which actually carries out the molding method of the present invention described above with reference to FIGS. 3 and 4. FIG. 6 is a partial side view schematically illustrating a state of the molding device for carrying out the molding method of the present invention, when viewed from a lateral side. Further, FIG. 7 is an enlarged sectional view of the casting mold 4 in the molding device of FIG. 6, when viewed from a lateral side. As illustrated in FIG. 6, the configuration of injecting the melt of metallic glass from above is adopted, and the melt is injected into the casting mold 4 through the injection port 5a on the upper surface on the right side of the casting mold 4. A lower end of an injection tube 11 for injecting the melt into the casting mold 4 ascends or descends as indicated by the arrow X, and is connected to the injection port 5a during injection and distanced from the injection port 5 a during non-injection. Further, the pellet 3 (see FIGS. 3 (a) and 3(b)), which is obtained by cutting the standard rod 2 into a portion corresponding to one shot for the casting mold 4, is arranged in a pellet storage tube 13, and the pellet 3 is heated with a ceramic heater positioned below the pellet storage tube 13. In this manner, the metallic glass material is melted. Then, the melt of the metallic glass is injected into the casting mold 4 through the melt injection tube 11 while being pressurized with inert gas from the lower end. Herein, the inert gas to be used for pressurization during the injection of the melt is guided from a gas introduction port 14 formed above the pellet storage tube 13 to the lower end of the injection tube 11.
The coil 5 is wound around the periphery of the casting tube 4, and the casting mold 4 is subjected to heating treatment when a high-frequency current flows through the coil 5 from the AC power source as described above (see FIG. 3(d) and STEP 6 of FIG. 4). Further, the casting mold 4 is supported by a support member 10. The casting mold 4 and the support member 10 are arranged in a vacuum chamber 15 indicated by the dotted line so that the melt (metallic glass) can spread sufficiently inside the mold when the casting mold 4 is evacuated through a gap of the casting mold 4, a left-end opening 4b, and a right-end opening 4c during the injection of the melt into the casting mold 4. Further, the melt 7 described above is subjected to the heating treatment and the pressurizing treatment simultaneously in the casting mold 4 (see FIG. 3(d) and STEP 7 of FIG. 4), and in the configuration adopted in FIG. 6, the melt 7 is pressurized by holding the left-end opening 4b and the right-end opening 4c from both sides with pressurizing pistons (arranged in side parts denoted by reference numeral 8). Although the movement of the pressurizing piston 8 is not shown, a linear slider 9 that reciprocates in a direction of the arrow Y may be used or a dedicated actuator may be provided instead. Further, as the method of pressurizing the melt 7, a method of pressurizing the melt 7 with inert gas from the left-end opening 4b and/or the right-end opening 4c may be adopted.
Next, a detailed example of the casting mold 4 illustrated in FIG. 6 is described with reference to the side sectional view of FIG. 7(a). In FIG. 7(a), the coil 5 is omitted. First, when a lower end nozzle of the injection tube 11 (illustrated only in FIG. 6) is connected to the injection port 4a positioned on the right side of the casting mold 4, the melt 7 of metallic glass is injected into the casting mold 4. As illustrated in FIG. 7 (b), the injection port 4a extends from a deepest part of a receiving portion 4d that is an elliptical recessed part to a molding gap 4j in the casting mold 4. The receiving portion 4d serves as a guide hole for guiding the lower end nozzle of the injection tube 11 into the injection port 4a. Inordertoinject the melt 7 through the injection port 4a, the melt 7 is pushed into the casting mold 4 while being pressurized with inert gas such as argon gas as described above. The molding gap 4j extends in an axial direction in the casting mold 4, and the melt is filled into the casting gap 4j.
A cooling water path through which cooling water flows in the axial direction is arranged on the periphery of the casting mold 4, and the water having cooled the casting mold 4 is discharged outside through a cooling water pipe on the left end. For example, a cooling water path 4g for an upper die, which extends in the axial direction, is formed in the upper die 4-1. Then, the cooling water path 4g for an upper die is connected to a cooling water pipe 4e for an upper die on the left end of the casting mold 4, and the cooling water is discharged outside. Herein, the cooling water path 4g for an upper die extends from a left-end vicinity of the casting mold 4 to the right side in the axial direction and returns to the left side in the axial direction when reaching the right-end vicinity of the casting mold 4 to reach the cooling water pipe 4e for an upper die. This configuration is also apparent from FIG. 7(c), which is a left side view of FIG. 7(a). For example, the cooling water flows into the casting mold 4 through the cooling water pipe 4e for an upper die on the right side of FIG. 7(c) and the cooling water is discharged from the cooling water pipe 4e for an upper die on the left side. Note that, in the above-mentioned description, the case where the cooling water path 4g for an upper die returns once is described, but the case where the cooling water path 4g for an upper die returns a plurality of times to enhance the cooling performance is also considered.
Further, the same cooling configuration as that of the upper die 4-1 is also arranged in the lower die 4-2. For example, the cooling water path 4g for an upper die, which extends in the axial direction, is formed in the lower die 4-2. The cooling water path 4h for a lower die is connected to a cooling water pipe 4f for an upper die on the left end of the casting mold 4, and the cooling water is discharged outside. The cooling water path 4h for a lower die extends from the left-end vicinity of the casting mold 4 to the right side in the axial direction and returns to the left end in the axial direction when reaching the right-end vicinity of the casting mold 4 to reach the cooling water pipe 4f for a lower die in the same way as the above. Note that, both end portions of the casting mold 4 are held by the support member 10 as described with reference to FIG. 6 and the like.
Next, a molded article molded through use of the method of molding an amorphous alloy such as metallic glass of the present invention is described. Herein, a rotor of a uniaxial eccentric screw pump is exemplified as a molded article. Now, the rotor serving as a metallic glass molded article (denoted by reference numeral 130 in FIG. 8) and a uniaxial eccentric screw pump 100 including the rotor as one component are described.
FIG. 8 illustrates the uniaxial eccentric screw pump 100. The uniaxial eccentric screw pump 100 is mounted, for example, at an arm tip end or the like of an industrial robot, and ejects and applies an appropriate amount of liquid or the like to a desired place from a tip end nozzle 112a. The uniaxial eccentric screw pump 100 is a so-called rotary displacement pump, and receives a stator 120, the rotor 130, a power transmission mechanism 150, and the like in a casing 112, as illustrated in FIG. 8. The casing 112 is a metallic tubular member, and a needle (first opening) 114a is provided at the nozzle 112a mounted on one end side in a longitudinal direction. Further, an outer circumferential portion of the casing 112 has an opening (second opening) 114b. The opening 114b communicates to an inner space of the casing 112 in an intermediate portion 112d positioned in an intermediate part in the longitudinal direction of the casing 112.
The needle 114a and the opening 114b respectively serve as a suction port and an ejection port of the pump 100. More specifically, the uniaxial eccentric screw pump 100 is capable of pumping a fluid so that the needle 114a serves as the ejection port and the opening 114b serves as the suction port when the rotor 130 is rotated in a forward direction. On the contrary, the uniaxial eccentric screw pump 100 is capable of pumping a fluid so that the needle 114a serves as the suction port and the opening 114b serves as the ejection port when the rotor 130 is rotated in a backward direction. In the uniaxial eccentric screw pump 100, the rotor 130 is operated so that the needle 114a serves as the ejection port and the opening 114b serves as the suction port.
The stator 120 is a member being formed of an elastic body or a resin typified by a rubber and having a substantially cylindrical external shape. The material for the stator 120 is appropriately selected depending on the kind, characteristics, and the like of a fluid to be conveyed through use of the uniaxial eccentric screw pump 100. The stator 120 is received in a stator mounting portion 112b positioned adjacent to the needle 114a in the casing 112. An outer diameter of the stator 120 is substantially the same as an inner diameter of the stator mounting portion 112b. Therefore, the stator 120 is mounted on the stator mounting portion 112b in a state in which an outer circumferential surface of the stator 120 is substantially held in close contact with an inner circumferential surface of the stator mounting portion 112b. Further, one end side of the stator 120 is held by the nozzle 112a in an end portion of the casing 112.
As illustrated in FIG. 8, an inner circumferential surface 124 of the stator 120 has a double threaded multi-stage female screw shape. More specifically, a through-hole 122 extending in the longitudinal direction of the stator 120 and being twisted at the above-mentioned pitch is formed in the stator 120. The stator 120 has a multi-stage (d-stage) female screw shape with a length that is d times (d=natural number) as large as a reference length S, which is a length L (length obtained by multiplying a length of the pitch by the number of threads) of a lead of the female screw shape portion formedinside. Further, the through-hole 122 is formed so that a sectional shape thereof (opening shape) has a substantially elliptical shape even in a cross-section at any position in the longitudinal direction of the stator 120.
An inner diameter D_i of the female screw shape portion formed by the inner circumferential surface 124 of the stator 120 is set in a stepwise manner so as to be enlarged at every step proceeding in the longitudinal direction by the length L from the opening 114b side (right side of FIG. 8) serving as the suction port to the needle 114a side (left side of FIG. 10) serving as the ejection port.
The rotor 130 is an axis body made of a metal and had a single-threaded multi-stage eccentric male screw shape. More specifically, the length L of the lead of the rotor 130 is the same as that of the stator 120 described above. Further, the rotor 130 is formed so as to have a multi-stage (d-stage) male screw shape with a length that is d times (d=natural number) as large as the reference length S corresponding to the length L of the lead. The rotor 130 is formed so that the sectional shape thereof has a substantially true circle shape even in a cross-section at any position in the longitudinal direction. The rotor 130 is inserted into the through-hole 122 formed in the stator 120 described above and eccentrically rotatable freely in the through-hole 122.
An outer diameter of the portion formed into the male screw shape of the rotor 130 is set in a stepwise manner so as to be reduced at every step proceeding in the longitudinal direction by the length L from the suction side (right side of FIG. 8) to the ejection port side (needle 114a side (left side of FIG. 8)). When the rotor 130 is inserted into the stator 120, an outer circumferential surface 132 of the rotor 130 and the inner circumferential surface 124 of the stator 120 are brought into close contact with each other at the respective tangents, and a fluid conveyance path 140 is formed between the inner circumferential surface 124 of the stator 120 and the outer circumferential surface of the rotor 130. The fluid conveyance path 140 serves as a multi-stage (d-stage) flow path with a length that is d times as large as the reference length S of the lead in the axial direction of the stator 120 and the rotor 130, assuming that the reference length S is the length L of the lead of the stator 120 and the rotor 130 described above. Further, the fluid conveyance path 140 extends in a spiral shape in the longitudinal direction of the stator 120 and the rotor 130.
Further, the fluid conveyance path 140 proceeds in the longitudinal direction of the stator 120 while rotating in the stator 120 when the rotor 130 is rotated in the through-hole 122 of the stator 120. Therefore, when the rotor 130 is rotated, a fluid can be conveyed sucked into the fluid conveyance path 140 from one end side of the stator 120, and the fluid can be conveyed to the other end side of the stator 120 while being confined in the fluid conveyance path 140 to be ejected on the other end side of the stator 120. The pump 110 of this embodiment is capable of pumping the fluid sucked through the opening 114b to eject the fluid through the needle 114a, when the rotor 130 is rotated in a forward direction.
The power transmission mechanism 150 is provided so as to transmit power from a power source (not shown), such as a motor provided outside of the casing 112, to the rotor 130 described above. The power transmission mechanism 150 includes a power transmission portion 152 and an eccentric rotation portion 154. The power transmission portion 152 is provided on one end side in the longitudinal direction of the casing 112, more specifically, on an opposite side of the nozzle 112a described above (hereinafter also referred to simply as "base end side"). The power transmission portion 152 includes a drive shaft, and is connected to a driving machine 165 formed of a servo motor and a speed reducer through the drive shaft. The drive shaft can be rotated by operating the driving machine 165. A shaft seal 161 formed of a Variseal 163, another mechanical seal, a ground packing, or the like is provided in the vicinity of the power transmission portion 152, with the result that the fluid to be conveyed is prevented from leaking to the driving machine 165 side.
The eccentric rotation portion 154 is a portion for connecting the drive shaft and the rotor 130 to each other so that power can be transmitted. The eccentric rotation portion 154 includes a coupling shaft 162 and two coupling bodies 164, 166. The coupling shaft 163 is formed of a coupling rod, a screw rod, or the like, which are publicly known in the related art. The coupling body 164 couples the coupling shaft 162 and the rotor 130 to each other, and the coupling body 166 couples the coupling shaft 162 and a drive shaft 156 to each other. The coupling bodies 164, 166 are each formed of a universal joint, which is publicly known in the related art and are capable of transmitting a rotation force, which is transmitted through the drive shaft, to the rotor 130 to eccentrically rotate the rotor 130.
In the above, the embodiment and concept of the method of molding an amorphous alloy and the molded article produced by the molding method of the present invention are described. However, the present invention is not limited thereto. Those skilled in the art would understand that other alternative examples and modified examples can be obtained without departing from the spirit and teaching described in the claims, the specification, etc.

Reference Signs List

1: rotor
2: standard rod
3: pellet
4: casting mold
4a: injection port
4b: left-end opening
4c: right-end opening
4d: receiving portion
4e: cooling water pipe for upper die
4f: cooling water pipe for lower die
4g: cooling water path for upper die
4h: cooling water path for lower die
4i: injection port
4j: molding gap
5: coil
6: rolling die
6a: upper rolling die
6b: lower rolling die
7: melt (metallic glass)
8: pressurizing piston
9: linear slider
10: support member
11: melt injection tube
12: ceramic heater
13: pellet storage tube
14: gas introduction port
15: vacuum chamber
16: actuator

Claims

A method of molding an amorphous alloy, comprising:
a melting step of melting an alloy;

a differential-pressure casting step of injecting a melt of the alloy into a casting mold positioned below the melt and evacuating the casting mold; and

a processing step of processing the melt by pressurizing a casting metal in the casting mold under a high-temperature state while keeping the melt in a supercooled state.
A method of molding an amorphous alloy according to claim 1, wherein the alloy comprises metallic glass.
A method of molding an amorphous alloy according to claim 1 or 2, wherein the casting metal is processed and pressurized in the processing step in a supercooling temperature range corresponding to an intermediate temperature lower than a crystallization temperature of the casting metal and higher than a glass transition temperature of the casting metal.
A method of molding an amorphous alloy according to claim 1, wherein a temperature in the high-temperature state in the casting mold is controlled by causing a high-frequency current to flow through a coil provided on a periphery of the casting mold.
A method of molding an amorphous alloy according to claim 1, wherein a temperature in the high-temperature state in the casting mold is controlled by irradiating the casting mold with infrared light.
A method of molding an amorphous alloy according to any one of claims 1 to 5, wherein the melt is pressurized in the processing step by pressurizing the melt with gas through a hole formed in the casting mold.
A method of molding an amorphous alloy according to any one of claims 1 to 5, wherein the melt is pressurized in the processing step by pressurizing the melt with an actuator through a hole formed in the casting mold.
A molded object produced from an amorphous alloy by the method of molding an amorphous alloy according to claims 1 to 7,
the molded article comprising a rotor of a uniaxial eccentric screw pump.