TWI615859B - Anisotropic magnet manufacturing method and magnet manufacturing equipment - Google Patents

Description

Anisotropic magnet manufacturing method and magnet manufacturing equipment

The invention relates to an anisotropic magnet manufacturing method, in particular to an anisotropic magnet manufacturing method, in which the two steps of hot pressing and thermal deformation use only a single mold to compact and deform the magnetic powder.

In general, the existing Nd-Fe-B Magnet manufacturing method includes a sintered magnet process, a plastic rubber magnet process, a heat-cured magnet process, a cementation process, and a hot press forming process. Among them, the NdFeB magnet produced by the hot press forming process mainly comprises an isotropic NdFeB hot-press magnet (MQII) and an anisotropic NdFeB hot-press magnet (MQIII), and the NdFeB heat The magnet has high magnetic properties (maximum magnetic energy product up to 30~50 MGOe), and the hot magnetizing process can align the easy magnetization axis of the magnet in the radial direction, so that an elongated ring magnet which is easy to assemble can be manufactured. Furthermore, during the magnetization process, the ring magnet can change the number of magnetizing poles and the magnetic declination by changing the position and number of the magnetizing coil. Accordingly, the NdFeB magnet produced by the hot press forming process can be widely applied to various motors, generators, compressors, speakers, or magnetic bearings, such as electric assisted steering motors used in electric vehicles (Electric). Power Steering (EPS) has a high demand for anisotropic NdFeB hot-press magnets, making the hot press forming process one of the mainstream manufacturing methods for NdFeB magnets in recent years.

The conventional method for manufacturing neodymium iron boron magnet mainly dissolves cerium, iron, boron and other metal raw materials (for example, cobalt) to form a metal solution, and the metal solution can be quickly quenched to produce a metal foil by rapid-quenching. The metal flakes were further pulverized to prepare a magnetic powder. Then, the manufacturing method sequentially employs cold pressing and hot pressing. The process compacts the magnetic powder to increase the density of the magnetic powder to form a magnetic powder. The above cold pressing process is usually carried out by preliminary pressing to bring the magnetic powder density to 50-60%. The above hot pressing process usually needs to be heated to about 660 ° C and then pressurized, so that the magnetic powder can form a magnetic powder having a compacted density of 80-99% to produce an isotropic NdFeB magnet semi-finished product. Next, the isotropic NdFeB magnet semi-finished product is subjected to a hot plastic deformation process to form an anisotropic NdFeB magnet, and the hot deformation process generally needs to be raised to about 800 °C. The NdFeB magnet manufacturing method can further mechanically process the anisotropic NdFeB magnet to achieve the final desired shape.

However, on the one hand, the two steps of hot pressing and thermal deformation respectively use the hot pressing die and the hot deforming die to compact and deform the magnetic powder, which will increase the step complexity of the manufacturing method, and cause the existing NdFeB hot-press magnet. The overall process time is too long. On the other hand, in the process of manufacturing the NdFeB magnet, the above-mentioned isotropic NdFeB magnet semi-finished product is thermally deformed into an anisotropic NdFeB magnet, and there is also a ferroniobium when the hot press die is replaced with a hot deformable die. The boron magnet semi-finished product will firstly cool down and then heat up. Therefore, if the NdFeB magnet semi-finished product is heated again, the grain will grow and the grain will be coarse, and the magnetic properties of the NdFeB magnet will decrease. The characteristics of the NdFeB magnet are generally evaluated mainly by the residual magnetic flux density (Br) and the coercive force (iHc). The higher the Br value, the higher the orientation of the grain easy axis of magnetization, and the higher the iHc value, the smaller the grain size.

In view of the above, there is a need to provide an anisotropic magnet manufacturing method and a magnet manufacturing apparatus to solve the aforementioned problems.

The main object of the present invention is to provide an anisotropic magnet manufacturing method in which the two steps of hot pressing and thermal deformation use only a single mold to compact and deform the magnetic powder.

In order to achieve the above object, the present invention provides an anisotropic magnet manufacturing method comprising the steps of: providing a magnet manufacturing apparatus comprising: an inner mold, a double-acting outer mold and a punch, the double-acting outer mold Surrounded by Outside the inner mold; performing a hot pressing step, when the double acting outer mold is located at a first position relative to the inner mold, a first accommodating space is defined between the double acting outer mold and the inner mold The first accommodating space has a first inner diameter, and a magnetic ingot is placed in the first accommodating space, and the punch is used for hot pressing the magnetic ingot into an isotropic magnetic semi-finished product. The mold temperature of the first accommodating space is maintained at a first temperature range; and a thermal deformation step is performed, and the reticular outer mold is moved to a second position relative to the inner mold a second accommodating space is defined between the inner mold and the inner mold, the second accommodating space has a second inner diameter, the second inner diameter is greater than the first inner diameter, and the punch is used to be located at the first The isotropic magnet semi-finished product in the second accommodating space is thermally deformed into a hollow anisotropic magnet, and the mold temperature of the second accommodating space is directly heated to a second temperature range.

According to the magnet manufacturing apparatus of the present invention, on the one hand, the two steps of hot pressing and thermal deformation use only a single mold to compact and deform the magnetic powder, simplifying the step complexity of the anisotropic magnet manufacturing method, and reducing the existing NdFeB. The overall process time of the hot-pressed magnet. On the other hand, in the process of manufacturing the anisotropic magnet, the above-mentioned isotropic NdFeB magnet semi-finished product is thermally deformed into an anisotropic NdFeB magnet, and the hot pressing die is not required to be replaced by a hot deforming die, which can be avoided. The problem of lowering the temperature and then heating to 800 degrees Celsius will not cause the grains to grow and cause coarse grains. Therefore, the anisotropic NdFeB magnet produced by the anisotropic magnet manufacturing method of the present invention can have a small grain size, and the magnetic properties of the NdFeB magnet are further improved.

The above and other objects, features, and advantages of the present invention will become more apparent from the accompanying drawings.

1‧‧‧Magnetic manufacturing equipment

11‧‧‧ Internal model

111‧‧‧ end face

12‧‧‧Reintegration outer model

121‧‧‧through the cavity

13‧‧‧ Punch

14‧‧‧ machine stand

15‧‧‧Drive unit

16‧‧‧Drive unit

9‧‧‧Magnetic ingots

91‧‧‧Isotropic magnet semi-finished products

92‧‧‧ hollow anisotropic magnet

L1‧‧‧first inner diameter

L2‧‧‧second inner diameter

S1‧‧‧First accommodation space

S2‧‧‧Second accommodating space

S50‧‧ steps

S100‧‧‧ steps

S150‧‧ steps

S200‧‧‧ steps

S300‧‧‧ steps

S350‧‧‧ steps

1 to FIG. 5 are schematic cross-sectional views showing a method of manufacturing an anisotropic magnet according to a first embodiment of the present invention; 6 is a flow chart showing a method for manufacturing an anisotropic magnet according to a first embodiment of the present invention; and FIG. 7 is a flow chart showing a method for manufacturing an anisotropic magnet according to a second embodiment of the present invention.

Referring to Figures 1 to 5, there are shown schematic cross-sectional views showing a method of manufacturing an anisotropic magnet according to a first embodiment of the present invention. The anisotropic magnet manufacturing method mainly includes steps of hot pressing and thermal deformation. In the present embodiment, the anisotropic magnet is exemplified by an anisotropic Nd-Fe-B Magnet.

Referring to Figure 6, there is shown a flow chart of a method of manufacturing an anisotropic magnet of a first embodiment of the present invention. The anisotropic magnet manufacturing method includes: providing a magnet manufacturing apparatus in step S100; performing a hot pressing step in step S200; and performing a thermal deformation step in step S300.

Referring to FIG. 1, in step S100, a magnet manufacturing apparatus 1 is provided, which includes an inner mold 11, a double-acting outer mold 12, and a punch 13, and the double-acting outer mold 12 is disposed around the inner mold 11. outer. In detail, the double-acting outer mold 12 has a through-hole 121, and the inner mold 11 is shaped to be nested in the through-hole 121, so that the double-acting outer mold 12 is circumferentially disposed on the inner mold 11. outer. The magnet manufacturing apparatus 1 further includes a machine base 14 to which the inner mold 11 is fixedly disposed. The inner mold 11, the double-acting outer mold 12, and the punch 13 may be made of a high-temperature resistant material having a melting point of more than 1600 ° C or higher, such as tungsten steel.

Referring to FIG. 2 and FIG. 3, in step S200, a hot pressing step is performed, when the double-acting outer mold 12 is in a first position (in the embodiment, the end surface 111 of the inner mold 11 is located in the through-die A first accommodating space S1 is defined between the double-acting outer mold 12 and the inner mold 11. The first accommodating space S1 has a first inner diameter L1 (shown in FIG. 1). Will be a magnetic The ingot 9 is placed in the first accommodating space S1, and the punch 13 is driven by a driving unit 15 (for example, hydraulic power) to heat-press the magnetic ingot 9 into an isotropic magnet semi-finished product 91. The mold temperature of the first accommodating space S1 is maintained at a first temperature range (for example, 580-640 ° C). In the hot pressing step, the magnetic powder can be formed into a magnetic powder having a compacted density of 80-99% to produce an isotropic NdFeB magnet semi-finished product.

Referring to FIG. 4 and FIG. 5, in step S300, a thermal deformation step is performed, when the double-acting outer mold 12 is moved relative to the inner mold 11 by being driven by another driving unit 16 (for example, hydraulic power). In a second position (in the embodiment, the end surface 111 of the inner mold 11 is located at the other end of the through hole 121), a second volume is defined between the double-acting outer mold 12 and the inner mold 11. The second accommodating space S2 has a second inner diameter L2 (shown in FIG. 1 ), and the second inner diameter L2 is greater than the first inner diameter L1 , and the punch 13 is driven by the driving unit 15 . (for example, hydraulic power) is driven, and the isotropic magnet semi-finished product 91 located in the second accommodating space S2 is thermally deformed into a hollow anisotropic magnet 92, and the second accommodating space S2 is molded. The temperature is directly raised to a second temperature range (for example, 780-830 ° C).

Referring to Figure 7, there is shown a flow chart of a method of manufacturing an anisotropic magnet of a second embodiment of the present invention. The anisotropic magnet manufacturing method includes: performing a milling step in step S50; providing a magnet manufacturing apparatus in step S100; performing a cold pressing step in step S150; and performing a hot pressing in step S200 Step; in step S300, performing a thermal deformation step; and in step S350, performing a mechanical processing step. The hot pressing step and the thermal deformation step of the second embodiment are substantially similar to the hot pressing step and the thermal deformation step of the first embodiment.

In the second embodiment, the anisotropic magnet manufacturing method further comprises a milling step (step S50) for pulverizing the metal flake into a magnetic powder; a cold pressing step (step S150), placing the magnetic powder on the In the accommodating space, the magnetic powder is compacted into the magnetic ingot; and, a mechanical plus In the working step, the anisotropic NdFeB magnet is machined.

In detail, in the milling step, bismuth, iron, boron and other metal materials (for example, cobalt) are dissolved to form a metal solution, and the metal solution can be quickly quenched to produce a metal foil by (rapid-quenching). The metal flakes were further pulverized to prepare a magnetic powder. In the cold pressing step, preliminary pressing is performed to compact the magnetic powder to increase the density of the magnetic powder so that the magnetic powder has a density of 50-60%. In the machining step, the anisotropic magnet manufacturing method can further mechanically process the anisotropic NdFeB magnet to achieve the final desired shape of the hollow anisotropic NdFeB magnet.

According to the magnet manufacturing apparatus of the present invention, on the one hand, the two steps of hot pressing and thermal deformation use only a single mold to compact and deform the magnetic powder, simplifying the step complexity of the anisotropic magnet manufacturing method, and reducing the existing NdFeB. The overall process time of the hot-pressed magnet. On the other hand, in the process of manufacturing the anisotropic magnet, the above-mentioned isotropic NdFeB magnet semi-finished product is thermally deformed into an anisotropic NdFeB magnet, and the hot pressing die is not required to be replaced by a hot deforming die, which can be avoided. The problem of lowering the temperature and then heating to 800 degrees Celsius will not cause the grains to grow and cause coarse grains. Therefore, the anisotropic NdFeB magnet produced by the anisotropic magnet manufacturing method of the present invention can have a small grain size, a grain size of <100 nm, and further the magnetic properties of the NdFeB magnet are further improved.

In the above, it is merely described that the present invention is an embodiment or an embodiment of the technical means for solving the problem, and is not intended to limit the scope of implementation of the present invention. That is, the equivalent changes and modifications made in accordance with the scope of the patent application of the present invention or the scope of the invention are covered by the scope of the invention.

1‧‧‧Magnetic manufacturing equipment

11‧‧‧ Internal model

12‧‧‧Reintegration outer model

13‧‧‧ Punch

15‧‧‧Drive unit

92‧‧‧ hollow anisotropic magnet

S2‧‧‧Second accommodating space

Claims (10)

An anisotropic magnet manufacturing method comprising the steps of: providing a magnet manufacturing apparatus, comprising: an inner mold, a double-acting outer mold and a punch, the double-acting outer mold being disposed around the inner mold; Performing a hot pressing step, when the re-acting outer mold is located at a first position relative to the inner mold, a first accommodating space is defined between the double-acting outer mold and the inner mold, and the first accommodating space is The space has a first inner diameter, and a magnetic ingot is placed in the first accommodating space, and the punch is used for hot pressing the magnetic ingot into an isotropic magnetic semi-finished product. The mold temperature of the space is maintained at a first temperature range; and a thermal deformation step is performed, and when the double-acting outer mold is moved to a second position relative to the inner mold, the double-acting outer mold and the inner mold a second accommodating space is defined, the second accommodating space has a second inner diameter, the second inner diameter is larger than the first inner diameter, and the punch is used to be located in the second accommodating space The isotropic magnet semi-finished product is thermally deformed into a hollow anisotropic magnet, and the mode of the second accommodating space at this time Directly heated to a second temperature range. The method for manufacturing an anisotropic magnet according to claim 1, wherein the hollow anisotropic magnet is an anisotropic NdFeB magnet (Nd-Fe-B Magnet), and the first temperature range is 580- 640 ° C, and the second temperature range is 780-830 ° C. The method for manufacturing an anisotropic magnet according to claim 1, further comprising: performing a milling step for pulverizing the metal flake into a magnetic powder. The method for manufacturing an anisotropic magnet according to claim 3, further comprising: performing a cold pressing step for compacting the magnetic powder into the magnetic ingot. The method for manufacturing an anisotropic magnet according to claim 1, further comprising: performing a mechanical processing step to achieve a final desired shape of the hollow anisotropic magnet. A magnet manufacturing apparatus comprises: a machine base fixing seat; an inner mold fixedly disposed on the machine base fixing seat; a double-acting outer mold disposed around the inner mold, wherein the re-acting outer mold When the inner mold is moved to the first and second positions, the first and second accommodating spaces are respectively defined between the double-acting outer mold and the inner mold, and the first and second accommodating spaces respectively have a first and a second inner diameter, wherein the second inner diameter is greater than the first inner diameter, the mold temperature of the first accommodating space is maintained at a first temperature range, and the mold temperature of the second accommodating space is directly raised to one a second temperature range; and a punch, wherein the punch is used to compact one of the magnetic ingots in the first accommodating space into an isotropic direction when the reticular outer mold is moved to the first position The magnetic semi-finished product; the punch is used to extrude the isotropic magnet semi-finished product located in the second accommodating space into a hollow anisotropic magnet when the reticular outer mold is moved to the second position. The magnet manufacturing apparatus according to claim 6, wherein the hollow anisotropic magnet is an anisotropic NdFeB magnet (Nd-Fe-B Magnet), and the first temperature range is 580-640 ° C. And the second temperature range is 780-830 °C. The magnet manufacturing apparatus according to claim 6, wherein the inner mold, the double-acting outer mold, and the punch are made of a high temperature resistant material having a melting point of more than 1600 °C. The magnet manufacturing apparatus of claim 8, wherein the high temperature resistant material is tungsten steel. For example, the magnet manufacturing equipment described in claim 6 of the patent scope further includes: a driving unit for driving the punch; and another driving unit for driving the double-acting outer mold.