JPH04198402A - Production and apparatus for magnet element - Google Patents

Abstract

PURPOSE:To obtain a magnet element having fine crystal structure with a simple apparatus for short time by compression-compacting alloy powder for magnet obtd. with super rapid cooling method in a die having high electric resistance with one pair of punches having low electric resistance and at the same time, conducting electric current between the punches to heat the alloy powder. CONSTITUTION:The alloy powder 5 for magnet produced with the super rapid cooling method, is packed into compressing space 2 in the die 1 and compression-compacted with the upper and lower punches 4a, 4b and at the same time, the electric current is conducted between the upper and lower punches with electric conduction heating device 5. The powder 3 is rapidly heated with resistance heat, and stickness among mutual powder particles is progressed and also the electric resistance in powder is reduced and current value for heating is increased, but in order to keep sintering condition to the constant and prevent excess temp. raising, the device 5 is worked and the conducted max. current value is automatically regulated. After passing the fixed time, the current for heating is shut off and the pressurizing force with the upper and lower punches is released and the compression-compacted magnet element is ejected to out of the die 1 with ascent of the punch 4b after radiating the heat through the die 1.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method and apparatus for manufacturing a magnet body, and particularly to a method and apparatus for manufacturing a magnet body, and particularly for manufacturing a magnet element with excellent magnetic properties economically and efficiently using a simple apparatus configuration. The present invention relates to a method and apparatus for manufacturing a magnet body that can form a magnet body.

(Prior Art) Generally, as a method for manufacturing a magnet body, a hot press method is employed in which magnet alloy powder is compressed and sintered at the same time.

The hot press equipment used includes a pressurizing device consisting of a die and a punch, a heating device that heats the entire pressurizing device,
An in-furnace atmosphere adjustment device that supplies inert sludge into the furnace and adjusts the atmosphere is constructed integrally within the furnace.

In manufacturing the magnet body, we first use rare earth elements,
Raw material powders such as transition metal elements such as iron and boron are melted and solidified to form a uniform ingot, and then the obtained ingot is crushed by a mechanical crushing means such as a stamp mill or a ball mill to obtain a predetermined particle size. Obtain magnet alloy powder. Next, the obtained magnet alloy powder is filled into the molding space formed between the die and the upper and lower punches, and the magnet alloy powder is heated to a predetermined temperature along with the die and the punch, and then the lower punch and the "-punch" are heated. A method was adopted in which the magnet alloy powder was compressed under a predetermined pressure, and after molding, the magnet body was extruded to the upper surface of the die using a lower punch.

(Problem to be Solved by the Invention) However, according to the conventional manufacturing method of a magnet body, an ingot obtained by casting raw material powder to a uniform composition was crushed by mechanical crushing means. This has the disadvantage that the crystal structure of the alloy powder is distorted, resulting in a decrease in magnetic properties.

On the other hand, in the method of compressing and sintering magnetic alloy powder with a fine crystal structure that has been crushed by an ultra-quenching method without using the mechanical crushing method described above, the crystals become coarse during sintering at high temperatures for a long time. However, it was difficult to obtain a high-density magnet body that maintained the original fine crystal structure.

Further, in the conventional hot pressing method, when heating the magnetic alloy powder to be solidified and molded, it is necessary to heat the entire pressing device consisting of a die and a punch using a heating device. As a result, the hot press apparatus becomes too large, requires a large amount of energy, and is uneconomical in that the heat loss increases proportionally.

Furthermore, when rare earth element-iron-boron based magnet alloy powder is produced by an ultra-quenching method, at least 70
It is necessary to heat it to a high temperature of 0°C or higher. However, there are few economical die or punch members that can withstand high temperature and high pressure loads that are applied repeatedly over a long period of time, and the disadvantage is that it is necessary to frequently replace the mold material, making operation management and maintenance management complicated. There was.

Furthermore, rare earth-iron-boron alloys for magnets have high reactivity, and have the drawback of welding to the die or damaging the die during long-term sintering.

In order to prevent the above-mentioned welding, a measure was taken to apply a mold release agent to the die in advance, but due to the thickness of the mold release agent, the dimensional accuracy of the shape of the molded magnet body may deteriorate. There were problems such as the great effort required to remove the mold release agent adhering to the product.

The present invention was made in order to solve the above problems, and it improves the magnetic properties by refining the crystal structure of magnet alloy powder and sintering it within a short time without damaging the fine crystal structure. It is an object of the present invention to provide a method and device for manufacturing a magnet body that can be operated and further simplify the device configuration.

[Structure of the invention]

(Means for Solving the Problems) The method for manufacturing a magnet body according to the present invention is to fill a molding space in a die with a large electrical resistance with a magnet alloy powder obtained by an ultra-quenching method, and It is characterized by compression molding using a pair of punches and simultaneously heating and solidifying the filled magnet alloy powder by the resistance heat generated by passing an electric current between the punches to form a magnet body.

Furthermore, the magnet body manufacturing apparatus according to the present invention uses a die made of a non-conductive material such as ceramic and a material made of copper to compression mold the magnet alloy powder filled in the molding space in the die from above and below. A pair of punches formed with a conductive part, an energization heating device that heats the magnet alloy powder by resistance heat by passing electricity between the punches, and an inert gas supplied into the molding space to create an atmosphere in the furnace. It is characterized by comprising a furnace atmosphere adjustment device for adjusting the atmosphere inside the furnace.

(Function) According to the method and apparatus for manufacturing a magnet body having the above configuration, since the powder for magnet alloy is formed by an ultra-quenching method,
It is possible to obtain a magnet body with ultra-fine crystal grain size and excellent magnetic properties. In addition, since mechanical crushing is not performed, it is possible to create a magnet body with less distortion in the crystal lattice and a high coercive force.

Further, during sintering, electricity is applied between the upper and lower punches, and only the magnetic alloy powder filled in the molding space is heated to a predetermined temperature in a short time, so that coarsening of the crystals is minimized and deterioration of magnetic properties is prevented. Moreover, since densification is completed in a short time, mass production by continuous molding becomes possible. Furthermore, since the heating operation is localized, the dies and punches themselves are not heated to high temperatures, and damage accidents due to fusion are less likely to occur, making it possible to significantly extend the life of mold materials such as dies. It also reduces the amount of heat that needs to be put into the equipment for heating.
It becomes an energy-saving device.

Furthermore, whether it is necessary to adjust the atmosphere in the furnace to prevent oxidation of the magnet alloy powder during heating, it is possible to limit the area to be adjusted only to the periphery of the die.

Furthermore, since the magnetic alloy powder obtained by the ultra-quenching method has a relatively low electrical resistance value, a high-voltage heating power source is not required.

Therefore, it is possible to downsize the energization heating device, the furnace atmosphere adjustment device, etc., and the entire magnet body manufacturing device can be configured to be simple and compact.

(Example) An example of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of the configuration of a manufacturing apparatus for carrying out the method for manufacturing a magnet body according to the present invention.

The apparatus for manufacturing a magnet body according to this embodiment is for compression molding a die 1- formed of a non-conductive material such as ceramic and a magnet alloy powder 3 filled in a molding space 2 in the die 1 from above and below. , a pair of upper and lower punches 4a, 4b made of a conductive material such as copper, and the upper and lower punches 4a, 4. b
A heating device 5 for heating the alloy powder 3 for magnets with resistance heat, and a furnace atmosphere adjusting device 6 for supplying inert scum etc. into the molding space 2 to adjust the furnace atmosphere. configured.

In addition, an ammeter 7 is disposed in the circuit that transmits power from the current heating device 5 to the upper and lower punches 4a and 4b, and the upper punch 4a
A detector 8 is provided to detect the amount of displacement f of the upper punch 4a, and this detector 8 detects the end point of the compression process when the striker 9 protruding from the side surface of the upper punch 4a comes into contact with it.

Next, a method for manufacturing a magnet body according to this embodiment will be explained in order of steps.

First, alloy powder 3 for magnets is prepared by an ultra-quenching method. In other words, a mixture of rare earth elements, transition metals, and O/boron is uniformly mixed in a predetermined ratio and melted in an arc furnace to form an alloy ingot.Then, this alloy ingot is remelted and melted through a minute nozzle. The material is squeezed onto a rotating cold surface to form an alloy in the form of a thin film or powder on the cold surface.

The magnet alloy powder 3 produced by extremely rapid cooling in this manner has an almost completely amorphous or extremely fine crystal structure.

The obtained alloy powder 3 for magnets is filled into the molding space 2 in the die 1, and compressed and molded at a predetermined pressure by the upper and lower punches 4a and 4b. be swept away. The alloy powder for magnets is rapidly heated by resistance heat, and in-phase bonding between the powder particles begins and progresses to fixation. As the adhesion progresses, the electrical resistance of the powder layer decreases and the heating current value increases.
In order to maintain the sintering conditions constant and prevent excessive temperature rise, the electrical heating device operates and the maximum current value that flows is automatically regulated.

After a certain period of time has elapsed, the heating current is cut off, and -1-lower punches 4a, 4. The pressing force caused by b is also released. The compression-molded magnet body radiates heat through the die and is then extracted out of the die 1 by the upward movement of the lower punch 4b.

The above manufacturing method and equipment for the magnet body are made using magnet alloy powder or ultra-quenching method, so the crystal grain size is fine and the magnet body has excellent magnetic properties with less distortion in the crystal lattice. Can you get it?

In addition, during sintering, only the magnet alloy powder 3 is heated in a short time by applying electricity between the upper and lower punches 4a and 4b, and densification is completed, so that coarsening of the crystals is minimized and deterioration of magnetic properties is prevented.

In addition, since the heating operation is localized to the alloy powder 3 for magnets, the mold material of Tyco Nato is not heated to high temperatures, and the life of the mold material is significantly extended, without causing an accident of fusion of raw materials. I can do something.

Furthermore, the amount of heat input is reduced, resulting in an energy-saving device.

In addition, it becomes possible to limit the target area for adjusting the furnace atmosphere to only the area around the die 1, and it becomes possible to downsize the furnace atmosphere adjustment device 6, the energization heating device 5, etc.
The entire manufacturing equipment can be downsized.

Next, more specific embodiments of the present invention will be described below.

Neodymium (Nd) 33%, iron (Fe) 6 as starting materials
A magnetic alloy ingot consisting of 6% boron (B) and 1% boron (B) was melted, and the molten mixture was jetted onto a rotating cold surface drum from an injection port (not shown) with a diameter of 500 μm, and rapidly cooled on the cold surface = 11- The obtained alloy flakes are stamp milled to a particle size of 500 μm.
The alloy powder 3 for magnets obtained by pulverizing into the following fine powder form was filled into the molding space 2 in the ceramic die 1. Next, the magnetic field is oriented at 12 K Oe and the molding is performed at a pressure of 1.5 t/clIf. After the furnace is evacuated using the furnace atmosphere adjustment device 6, electrodes are connected to the upper and lower punches 4a and 4'b and energized. At the same time, the upper and lower punches 4a and 4b were operated to compress and mold the magnet alloy powder 3 with a pressing force of 1.500 kg/cnf.

The current value was measured by an ammeter 7.

The face-to-face bonding progresses due to the resistance heat generated by the energization, and the magnet alloy powder 3 is consolidated, and the double punch 4a is displaced downward. The amount of displacement is detected by the detector 8.

The end point of consolidation is detected by a striker 9 that abuts a detector 8. The density, magnetic properties, etc. of the obtained magnet body were measured, and the characteristic values shown in Example 1 in Table 1 were obtained.

Further, as Comparative Example J, a magnet alloy powder obtained by mechanically crushing a magnet alloy ingot having the composition shown in Example 1 to adjust the particle size to 500 μm or less was used, and the same treatment was performed to produce a magnet body. The product was manufactured and its characteristic values were measured, and the results shown in Table 1 below were obtained.

As shown in Table 1, the manufacturing method of this example yields a magnet body with excellent magnetic properties such as residual magnetic flux density, coercive force, and maximum energy product. Moreover, all the magnet bodies of this example had high density.

Molded products of the same dimensions were also produced using a conventional hot press machine for comparison, but since the entire die is heated in the hot press, there was significant fusion with metal dies, and magnets with carbide dies. Because of the reaction with the alloy powder, a good compact could not be obtained.

In addition, when we used a ceramic die and filled it with Nd-Fe-B alloy flakes obtained by an ultra-quenching method to produce a magnet body of the same size, we obtained a molded product with a density close to the true density. However, as an industrial manufacturing method that requires continuous operation, the fusion with the ceramic die is significant.
Confirmed to be unsuitable.

C Effects of the Invention] As explained above, according to the method and apparatus for manufacturing a magnet element according to the present invention, since the magnet alloy powder is formed by an ultra-quenching method, crystals do not form. Second, it is possible to obtain a magnet body with less distortion in the crystal lattice and excellent magnetic properties.

In addition, during sintering, only the magnet alloy powder is heated in a short time by applying electricity between the upper and lower punches, and densification is completed, so that coarsening of the crystals is small and deterioration of magnetic properties is prevented.

Furthermore, since the heating operation is performed locally on the alloy powder for magnets, mold materials such as dies are not heated to high temperatures, making it less likely that accidents will occur due to fusion of raw materials, and greatly extending the life of the mold materials. . In addition, the amount of heat input is reduced,
This is an energy-saving device.

In addition, it is possible to limit the target area for adjusting the furnace atmosphere to only the area around the die, which makes it possible to downsize the furnace atmosphere adjustment device, energization heating device, etc., and the entire manufacturing equipment can be downsized. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a manufacturing apparatus for manufacturing a magnet body using the method for manufacturing a magnet body according to the present invention. ]...Dice, 2...Molding space, 3...Alloy powder for magnet, 4...Punch, 4a Upper punch, 4b...Lower punch,
5... Electrical heating device, 6... Furnace atmosphere adjustment device, 7
- Ammeter, 8... Detector, 9 - Sliding force.

Claims (2)

[Claims] 1. The alloy powder for magnets obtained by the ultra-quenching method was filled into the molding space in a die with high electrical resistance, and compression molded using a pair of punches with low electrical resistance.At the same time, the powder was filled using the resistance heat generated by passing an electric current between the punches. A method for manufacturing a magnet body, comprising forming a magnet body by heating and solidifying an alloy powder for a magnet. 2. A die made of a non-conductive material such as ceramic,
In order to compression mold the magnet alloy powder filled in the molding space in the die from above and below, a pair of punches made of a conductive material such as copper are used, and electricity is passed between the punches to compress the magnet alloy powder by resistance heat. 1. An apparatus for producing a magnet body, comprising: an energization heating device for heating; and a furnace atmosphere adjustment device for supplying inert gas into a molding space to adjust the furnace atmosphere.