JP2013098486A - Manufacturing method of rare earth magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a rare earth magnet with which a rare earth magnet precursor can be suppressed from being exposed in the atmosphere by continuously performing processing from cold molding to hot coining.SOLUTION: A method for manufacturing a rare earth magnet by using a manufacturing apparatus 10 comprising a molding machine including a die 4 and first and second punches 2 and 3 and a chamber 1 which accommodates the molding machine therein and of which the inside is controlled by an inert gas atmosphere, includes the steps of: filling the inside of a cavity C with a power (p) that becomes a rare earth magnet material, while bringing the inside of the chamber 1 into inert gas atmosphere or the like, pressing the filling powder (p) with the punches 2 and 3 and manufacturing a compact S1 through cold molding; and heating the compact S1 by moving the punches 2 and 3 relatively to the die 4 and moving the compact S1 to the outside of the die 4, returning the compact S1 held by the punches 2 and 3 into a hollow of the die 4 and manufacturing a rare earth magnet precursor S2 by performing hot coining on the compact S1 with the punches 2 and 3.

Description

  The present invention relates to a method for producing a rare earth magnet.

  Rare earth magnets using rare earth elements such as lanthanoids are also called permanent magnets, and their uses are used in motors for driving hard disks and MRI, as well as drive motors for hybrid vehicles and electric vehicles.

  Residual magnetization (residual magnetic flux density) and coercive force can be cited as indicators of the magnet performance of this rare earth magnet. However, in response to increased heat generation due to miniaturization of motors and higher current density, rare earth magnets used also The demand for heat resistance is further increasing, and how to maintain the coercive force of a magnet under high temperature use is one of the important research subjects in the technical field.

  Taking Nd-Fe-B magnets, one of the rare-earth magnets frequently used in vehicle drive motors, to refine crystal grains, use a composition alloy with a large amount of Nd, Attempts have been made to increase the coercivity by adding heavy rare earth elements such as high Dy and Tb.

  An outline of a method for producing a rare earth crystal magnet will be described with reference to the production method disclosed in Patent Document 1. For example, a fine powder obtained by rapidly solidifying an Nd—Fe—B-based metal melt is divided into a die, two upper and lower punches, and A molding body having a predetermined shape and dimensions is manufactured by cold pressing. Next, the molded body is taken out from the molding machine, and a lubricant such as graphite is applied to the molded body, and then stored in another molding machine, and a rare earth magnet is produced by continuously performing hot pressing and extrusion. is there.

  In contrast to the manufacturing method disclosed in Patent Document 1, it is also common to heat a molded body taken out from a molding machine and then perform coining (hot coining) to densify the molded body.

  Actually, any processed product that has been continuously subjected to hot pressing and extrusion processing, or processed product that has been subjected to hot coining, is a rare earth magnet precursor. A rare earth magnet is produced by applying a heavy rare earth element having high magnetic performance by various methods.

  Regardless of the manufacturing method disclosed in Patent Document 1 or the manufacturing method in which hot coining is performed on a molded body, the conventional manufacturing method is performed by cold pressing (cold press molding, After forming the molded body by cold forming), the molded body is once taken out from the molding machine, and the removed molded body is stored in a separate molding machine etc., where hot pressing and hot coining are performed, so the manufacturing process Therefore, it is impossible to avoid that the molded body is exposed to the atmosphere. Therefore, the molded body is oxidized, which causes a decrease in magnetic performance.

Japanese Patent No. 3818397

  The present invention has been made in view of the above-described problems. In the production of rare earth magnets, cold forming to hot coining are continuously performed, and the precursor is exposed to the atmosphere during the production of the rare earth magnet. It is an object of the present invention to provide a method for producing a rare earth magnet capable of preventing the precursor from being oxidized by exposure to the atmosphere and deteriorating the magnetic performance.

  In order to achieve the above object, a method of manufacturing a rare earth magnet according to the present invention includes a molding machine comprising a die, first and second punches movable in the hollow of the die, and housing the molding machine. A manufacturing method for manufacturing a rare earth magnet using a manufacturing apparatus comprising a chamber whose inside is controlled to a vacuum atmosphere or an inert gas atmosphere, wherein the chamber is a vacuum atmosphere or an inert gas atmosphere In this state, the cavity is filled with powder to be a rare earth magnet material, the filled powder is pressed with the first and second punches close to each other, and a compact is manufactured by cold forming. Step, with the molded body held by the first and second punches, move the first and second punches relative to the die to move the molded body to the outside of the die and heat the molded body. Held by the first and second punches The molded body back into the hollow of the die was, first, is made of a second step of producing a rare earth magnet precursor by performing hot coining the molded body of the second punch is brought close to one another.

  More specifically, the method for producing a rare earth magnet of the present invention is a method for producing a rare earth magnet precursor, but this specification defines this as a method for producing a rare earth magnet. Although it still has characteristics as a rare earth magnet, in reality, if heavy rare earth elements with high coercivity are diffused and permeated into the rare earth magnet precursor obtained by this manufacturing method, the high performance will eventually be achieved. The rare earth magnet will be manufactured.

  The manufacturing method of the present invention uses a manufacturing apparatus in which a molding machine is housed in a chamber, and takes out a rare earth magnet precursor and further a molded body that is a precursor thereof from the chamber under an inert gas atmosphere or the like. However, it is a manufacturing method that can completely eliminate exposure of the molded body and the like to the atmosphere by continuously manufacturing the molded body and further manufacturing the rare earth magnet precursor.

  Thus, with only one manufacturing device, from the production of the molded body by cold forming to the production of the rare earth magnet precursor by hot coining is performed continuously, in addition to inhibiting oxidation of the molded body, etc. It is possible to effectively eliminate the problem of handling labor when manufacturing molding and hot coining with separate molding machines (apparatuses) and the resulting decrease in manufacturing efficiency, thereby significantly improving the manufacturing efficiency. Furthermore, since the rare earth magnet production apparatus can be integrated into one apparatus, the production apparatus can be made compact and the apparatus space can be reduced.

  In the first step, for example, powder made of a quenched ribbon (quenched ribbon), which is fine crystal grains produced by liquid quenching, is filled into a cavity of a molding machine formed by a die and a punch, The filled powder is pressurized with the second punch to perform cold forming to produce a compact.

  Next, in the second step, the die is moved relative to the first and second punches while holding the molded body produced by the first and second punches (a form in which the die is moved). , A form in which the punch is moved, and a form in which both are moved).

  Heating means such as a heater for heating and induction heating coil are provided outside the die, and after the molded body is heated as desired by these heating means, the procedure is the reverse of moving the molded body to the outside of the die. Then, the heated molded body held by the first and second punches is returned to the inside of the die.

  Inside the die, the heated compact is pressed with the first and second punches, and coining is performed to produce a rare earth magnet precursor. Thus, the heating and coining of the molded body are generally defined as hot coining.

  From the first step to the second step, the inside of the chamber is a vacuum atmosphere or an inert gas atmosphere. This chamber may be a chamber with a glove box or a chamber with a robot hand.

  Here, as an embodiment of a manufacturing apparatus applied to the manufacturing method of the present invention, the die constituting the molding machine has a first hollow having a relatively large cross-sectional area and a second hollow having a relatively small cross-sectional area. The first punch is movable by sliding with the die in the first hollow, and the second punch is movable by sliding with the die in the second hollow. A manufacturing apparatus can be applied.

  Using the manufacturing apparatus of such a form, in the first step, cold forming is performed in the second hollow to produce a molded body, and in the second step, the first hollow is interposed. After the molded body is moved to the outside of the molding machine, it is heated and hot coining is performed in the first hollow to produce a rare earth magnet precursor.

  When the die has a hollow with a variable cross section, the heated compact can be effectively pressed in the hot coining in the second step, and the densification thereof can be achieved.

  As can be understood from the above description, according to the method for producing a rare earth magnet of the present invention, from a production of a molded body by cold forming to a production of a rare earth magnet precursor by hot coining in a single production apparatus. Therefore, the exposure of the molded body and rare earth magnet precursor to the atmosphere can be completely eliminated, the production efficiency of the rare earth magnet can be greatly improved, the manufacturing equipment is downsized and the equipment space is narrowed. Can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of Embodiment 1 of the manufacturing apparatus applied with the manufacturing method of the rare earth magnet of this invention. It is the schematic diagram which demonstrated the 1st step of Embodiment 1 of the manufacturing method of the rare earth magnet of this invention at the time of using Embodiment 1 of a manufacturing apparatus in order of (a) and (b). FIG. 3 is a schematic diagram illustrating the second step of the manufacturing method in the order of (a) and (b) following FIG. 2. FIG. 4 is a schematic diagram illustrating the second step of the manufacturing method in the order of (a) and (b) following FIG. 3. It is a schematic diagram of Embodiment 2 of a manufacturing apparatus. It is the schematic diagram which demonstrated the 1st step of Embodiment 2 of the manufacturing method of the rare earth magnet of this invention at the time of using Embodiment 2 of a manufacturing apparatus in order of (a) and (b). FIG. 7 is a schematic diagram illustrating the second step of the manufacturing method in the order of (a) and (b) following FIG. 6. FIG. 8 is a schematic diagram illustrating a second step of the manufacturing method in the order of (a) and (b) following FIG. 7. It is a schematic diagram of Embodiment 3 of a manufacturing apparatus. It is the schematic diagram which demonstrated the 1st step of Embodiment 3 of the manufacturing method of the rare earth magnet of this invention at the time of using Embodiment 3 of a manufacturing apparatus in order of (a) and (b). FIG. 11 is a schematic diagram illustrating the second step of the manufacturing method in the order of (a) and (b) following FIG. 10. FIG. 12 is a schematic diagram illustrating the second step of the manufacturing method in the order of (a) and (b) following FIG. 11.

  Hereinafter, an embodiment of a method for producing a rare earth magnet of the present invention and an embodiment of a production apparatus applied by this production method will be described with reference to the drawings.

(Embodiment 1 of a rare earth magnet manufacturing apparatus)
FIG. 1 is a schematic diagram of Embodiment 1 of a manufacturing apparatus applied in the method for manufacturing a rare earth magnet of the present invention. The manufacturing apparatus 10 shown in the figure includes a chamber 1, a die 4 accommodated in the chamber 1, first and second punches 2 and 3, first and second punches 2 and 3, and a die 4. The first main drive unit 5, the second main drive unit 6, and the sub drive unit 7 that are moved are roughly configured. The die 4 and the first and second punches 2 and 3 constitute a molding machine.

  In the chamber 1, there are provided an inert gas providing portion (not shown) for providing an inert gas such as argon gas and an attraction portion (not shown) for evacuating the chamber. In the manufacturing process, both the suction part and the inert gas providing part are actuated so that the inside of the chamber 1 can be formed in a desired inert gas atmosphere.

  The die 4 has a hollow with a variable cross section, and a first hollow 4a having a relatively large cross-sectional area and a second hollow 4b having a relatively small cross-sectional area communicate with each other to form an entire hollow (cavity C). In the first hollow 4a, the first punch 2 having the same cross section as that of the hollow 4a is arranged, and the first main drive unit 5 is operated to cause the first punch 2 to move in the first hollow 4a. The second punch 3 having the same cross section as that of the hollow 4b is arranged in the second hollow 4b and the second main drive unit 6 is operated to operate the second main body 6 in the second direction. The punch 3 slides in the second hollow 4b (X2 direction).

  Further, the sub drive unit 7 is attached to the die 4, and the die 4 can move relative to the first and second punches 2 and 3 by operating the sub drive unit 7 (X3 direction). It is like that.

  The first and second main drive units 5 and 6 and the sub drive unit 7 are both composed of hydraulic cylinders or air cylinders, and the sub drive unit 7 has a ring-shaped three-dimensional shape with a first inside. The main drive unit 5 is disposed. The drive shafts of the cylinders are defined so that the drive directions of the first and second main drive units 5 and 6 and the sub drive unit 7 are parallel to each other.

  The chamber 1 shown in the figure is preferably a chamber with a glove box, and all processes from manufacturing of a molded body by cold forming to manufacturing of a rare earth magnet precursor by hot coining, and further removal of the rare earth magnet precursor. In order to achieve full automation, a form in which a robot hand is attached inside and outside the chamber 1 can be applied.

  In addition, the drive control of the first and second main drive units 5 and 6 and the sub drive unit 7 (drive timing, drive speed, etc. of any one or more drive units) is performed by a control unit (not shown) It is executed by a computer having a central processing unit (CPU), ROM, RAM and a bus connecting them.

  The manufacturing apparatus 10 shown in the figure is mainly used for manufacturing a molded body for a rare earth magnet and then a rare earth magnet precursor in a cavity C formed by a die 4 and first and second punches 2 and 3. There is, however, no provision for other product manufacturing.

  Next, a method for producing a rare earth magnet using the production apparatus 10 shown in the figure, more specifically, a molded body that becomes a rare earth magnet and a method for producing a rare earth magnet precursor will be described below.

(Embodiment 1 of manufacturing method of rare earth magnet)
2a and 2b are schematic views illustrating the first step of the first embodiment of the method for manufacturing a rare earth magnet of the present invention in that order, and FIGS. 3a, b, and 4a and b show the manufacturing method in that order. It is the schematic diagram explaining the 2nd step.

  With the inside of the chamber 1 in an inert gas atmosphere, first, as shown in FIG. 2A, the cavity C is filled with the powder p for rare earth magnets.

  Here, for example, this powder p is a copper roll in which a molten alloy ingot is melted at a high frequency by a melt spinning method using a single roll in a furnace not shown in an Ar gas atmosphere whose pressure is reduced to 50 kPa or less to give a rare earth magnet It is produced by spraying into a thin ribbon (quenched ribbon) and coarsely pulverizing it.

  When the powder p is filled in the cavity C, the second main driving unit 6 is operated and the second punch 3 is slid so as to be close to the first punch 2 (X2 direction). Molding is performed to form a molded body S1 in the second hollow 4b as shown in FIG. 2b (first step of the manufacturing method).

  This compact S1 is composed of an Nd-Fe-B main phase (crystal grain size of about 50 nm to 200 nm) and a grain boundary phase of an Nd-X alloy (X: metal element) around the main phase. Is the body. Here, the Nd—X alloy constituting the grain boundary phase is made of Nd and at least one alloy of Co, Fe, Ga, etc., for example, Nd—Co, Nd—Fe, Nd—Ga, One of Nd-Co-Fe and Nd-Co-Fe-Ga, or a mixture of two or more of these, is in an Nd-rich state.

  In addition, the molded body S1 has an isotropic crystal structure in which the grain boundary phase is filled between crystal grains (main phases).

  Next, in order to make the structure of the compact S1 dense, hot coining is applied to the rare earth magnet precursor.

  In manufacturing the rare earth magnet precursor, the molded body S1 is moved in the cavity C.

  3a and 3b simulate the movement of the molded body S1 in that order. The movement of the molded body S1 from the cavity C to the outside of the cavity is to move the die 4 relative to the first and second punches 2 and 3 while maintaining the gripping posture of the molded body S1. Thus, the molded body S1 is moved from the cavity C to the outside of the cavity.

  That is, as shown in FIG. 3a, the sub-driving unit 7 is operated to move the die 4 to the second punch 3 side (X3 direction).

  Then, as shown in FIG. 3b, by further moving the die 4, the molded body S1 manufactured in the second hollow 4b is moved to the outside of the first hollow 4a and positioned here.

  As shown in the figure, an induction heating coil 8 is disposed around the molded body S1 outside the first hollow 4a in advance or after the molded body S1 is moved, and the first and second punches 2 and 3 are arranged. The molded body S1 is heated in the posture gripped by.

  When the molded body S1 is heated at a desired temperature and for a desired time, as shown in FIG. 4a, the sub-driving unit 7 is operated to move the die 4 to the first punch 2 side (X4 direction), and finally The die 4 is moved to a position where the end face 3a of the second punch 3 is flush with the end face 4a1 (cross-sectional change position) of the first hollow 4a, so that the second punch 3 is held by the first and second punches 2 and 3. The molded body S1 after heating in a different posture is accommodated in the first hollow 4a.

  Next, as shown in FIG. 4b, the first punch 2 is slid in the first hollow 4a (in the X1 direction), the heated compact S1 is pushed in, and hot coining is performed. The densified rare earth magnet precursor S2 is manufactured (second step of the manufacturing method).

  A rare earth magnet is manufactured by diffusing and penetrating the manufactured rare earth magnet precursor S2 with heavy rare earth elements having high coercive force performance, such as Dy and Tb, alloys of these with transition metals, and the like.

  According to the method for producing a rare earth magnet shown in the drawing, one production apparatus 10 can continuously produce from the production of the compact S1 by cold forming to the production of the rare earth magnet precursor S2 by hot coining, As a result, exposure of the molded body and rare earth magnet precursor to the atmosphere can be eliminated, and deterioration in magnetic performance due to oxidation when exposed to the atmosphere can be eliminated. Furthermore, since the rare earth magnet can be manufactured with one manufacturing apparatus, the apparatus can be made compact and the apparatus space can be reduced, and the manufacturing efficiency can be remarkably improved.

(Embodiment 2 of rare earth magnet manufacturing apparatus 2 and rare earth magnet manufacturing method)
FIG. 5 is a schematic diagram of a second embodiment of a manufacturing apparatus applied in the method for manufacturing a rare earth magnet of the present invention, and FIGS. 6a and 6b show, in that order, the second embodiment of the method for manufacturing a rare earth magnet of the present invention. It is the schematic diagram explaining the 1st step, and FIG. 7 a, b, FIG. 8 a, b is the schematic diagram explaining the 2nd step of the manufacturing method in that order. The difference in configuration between the manufacturing apparatus 10A and the manufacturing apparatus 10 shown in the figure is that the first punch has a double structure including an outer cylindrical punch 2B and an inner punch 2A. The first main drive portions 5A and 5B unique to the punches 2A and 2B are provided, and when the cylindrical punch 2B is fitted into the first hollow 4a of the die 4, the second of the die 4 The hollow 4b and the inner surface of the punch 2B are flush with each other.

  As shown in FIG. 6a, a rare earth magnet powder p is filled in the cavity C in a posture in which the cylindrical first punch 2B is fitted in the first hollow 4a of the die 4, and the first main drive unit 5A is operated to slide the first punch 2A (in the X1 direction) and pressurize the filling powder p. As shown in FIG. 6b, the end face of the inner first punch 2A is pushed into the end face of the cylindrical first punch 2B until it is flush, and the compact S1 is inserted into the second hollow 4b by cold forming. Form (first step of the manufacturing method).

  Next, as shown in FIG. 7a, the second main drive unit 6 and the first main drive units 5A and 5B are operated in synchronization, and the second punch 3 and the first punches 2A and 2B are synchronized. Slide (X2, X1, and X1 'directions), and as shown in FIG. 7b, the second punch 3 and the first punches 2A and 2B are moved in synchronization to produce the second hollow 4b. The formed molded body S1 is moved to the outside of the first hollow 4a and positioned here.

  As shown in the figure, an induction heating coil 8 is disposed around the molded body S1 outside the first hollow 4a, and the molded body S1 is held in a posture held by the first and second punches 2A and 3A. Heat.

  When the molded body S1 is heated at a desired temperature and for a desired time, as shown in FIG. 8a, the second main drive unit 6 and the first main drive units 5A and 5B are operated in synchronism, and the second punch 3 And the first punches 2A and 2B are slid in the direction opposite to that shown in FIG. 7a (X2, X1, and X1 ′ directions), and finally the end face 3a of the second punch 3 is the first one. By moving to a position that is flush with the end face 4a1 (cross-section change position) of the hollow 4a, the heated molded body S1 in a posture held by the first and second punches 2A and 3 is moved to the first hollow 4a. House inside.

  Next, as shown in FIG. 8b, the first punches 2A and 2B are slid synchronously in the first hollow 4a (X1 direction, X1 ′ direction), and the heated compact S1 is pushed in, By performing intercoining, the rare-earth magnet precursor S2 with a dense structure is manufactured (second step of the manufacturing method).

  In the illustrated example, the control mode is shown in which the die 4 is immovable and the first and second punches 2A, 2B, 3 are slid. For example, in the case of FIGS. 7a, 7b, and 8a, A control mode in which only 4 is slid may be used.

(Embodiment 3 of rare earth magnet manufacturing apparatus 3 and rare earth magnet manufacturing method)
FIG. 9 is a schematic diagram of Embodiment 3 of the manufacturing apparatus applied in the method of manufacturing a rare earth magnet of the present invention. FIGS. 10a and 10b are, in that order, Embodiment 3 of the method of manufacturing the rare earth magnet of the present invention. It is the schematic diagram explaining the 1st step, and FIG. 11a, b, FIG. 12a, b is the schematic diagram explaining the 2nd step of the manufacturing method in that order. The difference in structure between the manufacturing apparatus 10B and the manufacturing apparatus 10 shown in the figure is that the die 4A has a hollow 4c that is not a cross section, and the taper surface in which the edge end of the upper opening of the die 4A is cut out in a tapered shape. 4Aa.

  As shown in FIG. 10a, the cavity C is filled with the powder p for rare earth magnet, and the first main drive unit 5 is operated to slide the first punch 2 toward the second punch 3 (X1). Direction), the filled powder p is pressurized, and as shown in FIG. 10b, a compact S1 is formed in the cavity C by cold forming (first step of the manufacturing method).

  Next, as shown in FIG. 11a, the sub-drive unit 7 is operated to move the die 4A away from the second punch 3 (X3 direction), and as shown in FIG. Move it outside and position it here.

  As shown in the figure, an induction heating coil 8 is disposed around the molded body S1 outside the cavity C, and the molded body S1 is heated in a posture held by the first and second punches 2 and 3. .

  When the molded body S1 is heated at a desired temperature and for a desired time, as shown in FIG. 12a, the sub drive unit 7 is operated to move the die 4A to the second punch 3 side (X3 direction), and the molded body S1 is moved. By pressing and performing hot coining, as shown in FIG. 12b, a rare earth magnet precursor S2 with a dense structure is produced.

  Here, although the molded body S1 is thermally expanded by heating, the process of transition from FIG. 11b to FIG. 12a, that is, when the thermally expanded molded body S1 outside the cavity C is returned into the cavity C, Since the edge end of the upper opening has the tapered surface 4Aa, smooth insertion of the thermally expanded molded body S1 into the cavity C is guided, and the thermally expanded molded body S1 is damaged at the opening edge. Is effectively resolved.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Chamber, 2, 2A, 2B ... 1st punch, 3 ... 2nd punch, 4, 4A ... Die, 4a ... 1st hollow, 4b ... 2nd hollow, 4c ... Hollow, 5, 5A, 5B ... 1st main drive part, 6 ... 2nd main drive part, 7 ... Sub drive part, 8 ... Heating means (induction heating coil), 10, 10A, 10B ... Manufacturing apparatus, p ... Powder, S1 ... Molding Body, S2 ... rare earth magnet precursor

Claims (2)

A molding machine comprising a die and first and second punches movable in the hollow of the die, a chamber in which the molding machine is accommodated and the inside thereof is controlled in a vacuum atmosphere or an inert gas atmosphere, A manufacturing method for manufacturing a rare earth magnet using a manufacturing apparatus comprising:
In a state where the chamber is in a vacuum atmosphere or an inert gas atmosphere, the powder to be a rare earth magnet material is filled in the cavity, the filled powder is pressurized by bringing the first and second punches close to each other, and cooled. A first step of producing a molded body by hot forming,
While the molded body is held by the first and second punches, the first and second punches are moved relative to the die to move the molded body to the outside of the die and heat the molded body. 1. First, the molded body held by the second punch is returned into the hollow of the die, and the first and second punches are brought close to each other and hot coining is performed on the molded body to produce a rare earth magnet precursor. A method for producing a rare earth magnet comprising two steps. The die has a hollow in which a first hollow having a relatively large cross-sectional area communicates with a second hollow having a relatively small cross-sectional area, and the first punch moves by sliding with the die in the first hollow. The second punch can move freely by sliding with the die in the second hollow,
In the first step, cold forming is performed in the second hollow to produce a molded body,
In the second step, the molded body is moved to the outside of the molding machine through the first hollow and then heated, and hot coining is performed in the first hollow to produce a rare earth magnet precursor. The method for producing a rare earth magnet according to claim 1.

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