JPH0646972Y2 - Magnetic field press equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a magnetic field pressing apparatus used when manufacturing a permanent magnet from powder having large magnetic anisotropy, and in particular,
The present invention relates to a transverse magnetic field type magnetic field pressing device used when a raw material is a powdery rare earth magnetic material.

[Prior Art] Ferrites and rare earth cobalt alloys, which have been actively used in recent years as raw materials for permanent magnets, are magnetic materials exhibiting a hexagonal lattice crystal, and have a central axis direction of the hexagonal lattice crystal, that is, a c-axis direction. It is known as a magnetic material having a large magnetic anisotropy in which the magnetic energy difference between the coincident easy magnetization direction and the other direction is large.

Permanent magnets made from magnetic powders with large magnetic anisotropy such as ferrite and rare earth cobalt alloys, that is, ferrite magnets and rare earth cobalt magnets, are magnetized in each crystal so as to increase the magnetic anisotropy of the entire magnet. It is manufactured with the easy directions aligned, and as a result, it is a magnet with a high coercive force that makes it difficult for the magnetized magnetic force to escape.

By the way, the manufacture of a permanent magnet exhibiting such a high coercive force is generally performed by compressing a raw material powder obtained by crushing a magnetic material at high pressure to obtain a green compact, and after sintering the green compact,
Magnetization is performed, and as described above, compression molding is performed in a magnetic field in order to match the easy magnetization directions of the crystals, and the directions of the easy magnetization directions of the crystals are aligned at the same time as compression. It has become.

The above-described compression molding in a magnetic field has been conventionally performed by a device called a magnetic field pressing device. This magnetic field press device uses a raw material powder made of a magnetic material filled in a die,
Compression molding is performed with a punch in a state where a magnetic field is applied to the die, and is roughly classified into two types, a vertical magnetic field type and a transverse magnetic field type, depending on the direction of the magnetic field applied to the die.
The coexistence of the two types of the longitudinal magnetic field type and the transverse magnetic field type is related to the crystal structure of the magnetic material. Prior to explaining the reason, referring to FIG. 3 to FIG. The magnetic field press device will be briefly described.

In FIG. 3, reference numeral 1 is a vertical magnetic field type magnetic field pressing apparatus. This magnetic field pressing device 1 is inserted into a die 2 having a cylindrical raw material filling hole 2a, an upper punch 3 arranged above the raw material filling hole 2a of the die 2, and the raw material filling hole 2a from below. The lower punch 4 and the base end portions of the upper and lower punches 3 and 4
Wrapped around the outer circumference of 3a and 4a, the die 2 has an arrow H1
A vertical magnetic field generating coil 5 or 6 for applying a vertical magnetic field in the opposite direction is provided, and the lower punch 4 is magnetized by the vertical magnetic field generating coil 6 to fill the raw material powder 7 into the raw material filling hole 2a of the die 2. Or by filling the material by gravity dropping, the upper punch 3 is magnetized by the longitudinal magnetic field generating coil 5 and the upper and lower punches 3 and 4 are brought close to each other so that the raw material powder is compression-molded into a disk shape. It is characteristic that the easy magnetization direction of each crystal of the raw material powder 7 is aligned in the vertical direction by the vertical magnetic field applied to the pressing die 2.

On the other hand, reference numeral 8 in FIG. 4 is a transverse magnetic field type magnetic field pressing apparatus. This magnetic field pressing device 8 is provided with iron cores 9 and 10 and transverse magnetic field generating coils 11 and 12 on both sides of the pressing die 2 instead of the magnetic field generating coils 5 and 6 (see FIG. 3) of the above-mentioned longitudinal magnetic field type magnetic field pressing device 1. Is provided, and the raw material powder 7 is pressed into the die 2
When filling the raw material filling hole 2a of the transverse magnetic field generating coil 11,
12 is not driven, and raw powder 7 is produced by upper and lower punches 3 and 4.
Only in the case of compression molding, the transverse magnetic field generating coils 11 and 12 magnetize the iron cores 9 and 10 to apply a transverse magnetic field to the die 2 in the direction indicated by the arrow H2 in the figure or in the opposite direction. The feature is that the easy direction is aligned with the lateral direction.

The vertical magnetic field type and the horizontal magnetic field type coexist as the magnetic field pressing devices 1 and 8 for the following reason.

That is, as described above, both ferrite and rare earth cobalt alloy are hexagonal lattice crystals having an easy magnetization direction in the c-axis direction, but ferrite is a flat crystal that is short in the c-axis direction, and rare earth cobalt alloy is long in the c-axis direction. Since the crystals are vertically long, the c-axis of ferrite tends to be oriented in the vertical direction depending on the compression direction of the raw material powder by the upper and lower punches 3 and 4, and the difference of rare-earth cobalt alloys is that crystals tend to collapse and the c-axis is oriented in the horizontal direction. Occurs.

Since the directionality of the crystal is generated by the compression in this way, the longitudinal magnetic field type magnetic field press apparatus 1 is used when manufacturing a disc-shaped ferrite magnet, and when manufacturing a disc-shaped rare earth cobalt magnet. The transverse magnetic field type magnetic field press device 8 is used.

[Problems to be Solved by the Invention] By the way, it has been pointed out that the above-mentioned transverse magnetic field type magnetic field press apparatus 8 has the following drawbacks when compared with the longitudinal magnetic field type magnetic field press apparatus 1.

That is, in the conventional horizontal magnetic field type magnetic field press apparatus 8, unlike the vertical magnetic field type magnetic field press apparatus 1, the magnetic field for attracting the raw material powder 7 at the time of filling the raw material powder is not given to the pressing die 2, so that the raw material powder 7 The filling density is poor, and the depth of the raw material filling hole 2a required to fill the same amount of the raw material powder 7 as that of the vertical magnetic field type magnetic field pressing apparatus 1 becomes deeper. Therefore, in the transverse magnetic field type magnetic field press device 8, the material filling hole 2a of the pressing die 2 is inevitably lengthened and the pressing die 2 is enlarged, and the stroke amounts of the upper and lower punches 3 and 4 are increased. As a result, the size of the entire apparatus becomes large and the equipment cost also rises. Actual transverse magnetic field type magnetic field press device 8
Then, the filling depth of the raw material powder 7 may reach about 3 times that of the vertical magnetic field type.

In addition, since the die 2 is magnetized by the magnetic field generated by the transverse magnetic field generating coils 11 and 12 during compression molding, the transverse magnetic field generating coils
Even if the driving of 11 and 12 is stopped, the residual magnetism in the lateral direction remains in the die 2, so that the raw material powder 7 filled in the raw material filling hole 2a from the upper portion of the die 2 enters the raw material filling hole 2a. However, the raw material powder 7 having poor fluidity is not filled in the raw material filling hole 2a any more, the filling efficiency is deteriorated, and the productivity is greatly affected.

The present invention has been made in view of such a background, and provides a transverse magnetic field type magnetic field press device capable of filling raw material powder at high density and with high efficiency. The object is to reduce the equipment size to reduce the equipment cost and improve the productivity.

[Means for Solving the Problems] A magnetic field pressing apparatus of the present invention for solving the above problems includes a die for filling raw material powder, and a punch provided to compress the raw material powder filled in the die. A first magnetic field generating means for applying a magnetic field in one direction orthogonal to the punch compression direction to the die, and a second magnetic field generating means for applying a magnetic field in the same direction as the punch compression direction to the die. Be prepared.

[Operation] According to the above configuration, when the raw material powder is filled in the die, since the magnetic field in the same direction as the compression direction of the punch is applied to the die by the second magnetic field generating means, the raw material powder is drawn into the die and becomes high. Packed to a density.

Further, even if the residual magnetic field of the magnetic field orthogonal to the punch compression direction remains in the die due to the magnetic field applied to the die by the first magnetic field generating means during compression molding of the raw material powder, the second magnetic field producing means applies the magnetic field to the die. Due to the applied magnetic field, the raw material powder is efficiently filled in the die without bridging.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 13 is a die. The pressing die 13 is for molding a raw material powder made of a powdery magnetic material into a predetermined shape, and a raw material filling hole 13a penetrating the upper and lower surfaces of the pressing die 13 is formed in the center thereof. Raw material filling hole 1
The inner diameter of 3a is determined by the outer diameter of the manufactured permanent magnet. Further, a plurality of columns 14 are provided below the die 13. Each pillar 14 supports the pressing die 13 and is a connecting plate.
It is connected to the lower press rod 15 via 15a and can move in the vertical direction. Further, the lower punch holder 1 is provided at the center of the upper surface of the support plate 16a provided above the lower press rod 15.
7 is attached and is integrally fixed to a base plate 16 which is a main body of the magnetic field pressing apparatus by a support block 16b below the support plate 16a. A lower punch 17a is attached to the lower punch holder 17. The lower punch 17a is formed to have the same diameter as the inner diameter of the raw material filling hole 13a, and its tip is
As shown in FIG. 2, the raw material filling hole 13a is always fitted.

On the other hand, as shown in FIG. 1, the cylindrical upper punch 1 is positioned above the die 13 and aligned with the raw material filling hole 13a.
8 are arranged. The outer diameter of the upper punch 18 is set to be the same as the inner diameter of the raw material filling hole 13a, and the upper punch holder 19 supporting the upper punch 18 is moved to the raw material filling hole 13a of the pressing die 13 with the descending operation. It is designed to be fitted.

A pair of lateral magnetic field generating means (first magnetic field generating means) 20 is provided on the side of the die 13. The transverse magnetic field generating means 20 is formed by winding a transverse magnetic field generating coil 22 around the outer circumference of the iron core 21.
21 is excited to apply a transverse magnetic field to the die 13 in the direction of arrow H2 in the figure or in the opposite direction.

As shown in FIG. 2, a vertical magnetic field generating coil (second magnetic field generating means) 23 is provided below the die 13 to excite the lower punch holder 17 and the lower punch 17a. A magnetic field is applied to the die 13 in the direction of arrow H1 in the figure or in the opposite direction.

Next, a procedure for compression-molding the raw material powder 24 (see FIG. 2) containing the rare earth magnetic material as a component by the magnetic field pressing device having the above configuration will be described.

When compressing the raw material powder 24, the upper punch 18 is pressed.
In a state of standing above 13 the shoe box 25 filled with the raw material powder 24 is advanced, and the vertical magnetic field generating coil 23 excites the lower punch holder 17 and the lower punch 17a to apply a vertical magnetic field to the die 13. Then, the shoe box 25 advanced to the upper part of the raw material filling hole 13a by this longitudinal magnetic field.
The raw material powder 24 supplied from is attracted to and filled in the lower punch 17a.

Then, the driving of the vertical magnetic field generating coil 23 is stopped and the shoe box 25 is retracted, a horizontal magnetic field is applied to the die 13 by the horizontal magnetic field generating means 20, and subsequently, the upper punch holder 19 is lowered to form the upper punch 18 as a raw material. It is fitted into the filling hole 13a.
Then, the friction force generated between the upper punch 18 and the side wall of the raw material filling hole 13a moves the pressing die 13 downward, so that the lower punch
17 is moved relatively upward, as a result, the raw material powder 24 is compressed by the upper punch 18 and the lower punch 17, and the raw material powder 24 is easily magnetized by the transverse magnetic field applied by the transverse magnetic field generating means 20. The axis is aligned laterally to obtain a green compact having large magnetic anisotropy.

When the green compact is manufactured as described above, the driving of the horizontal magnetic field generating coil 22 of the horizontal magnetic field generating means 20 is stopped, and the upper punch 18 is moved above the pressing die 13 to press the green compact.
Take out from. Then, a vertical magnetic field is again applied to the die 13 by the vertical magnetic field generating coil 23 to fill the raw material powder 24, and the same procedure is repeated thereafter to sequentially compression-mold the raw material powder 24.

As described above, in the magnetic field pressing apparatus of the present embodiment, the vertical magnetic field applied to the die 13 by the vertical magnetic field generating coil 23 causes the raw material powder 24 to be drawn from the shoe box 25 into the raw material filling hole 13a and the lower punch 17a. Since it is filled in the upper part of the powder, the packing density of the raw material powder 24 is improved and the packing depth is also shortened. Further, since the longitudinal magnetic field applied by the longitudinal magnetic field generating coil 23 prevents bridging of the raw material powder 24 due to the residual magnetism in the lateral direction generated in the die 13 by the transverse magnetic field applied during compression molding, the raw material powder 24 is extremely efficient. Well filled. Therefore, a molded product having a high molding density can be obtained.

As described above, according to the magnetic field press device of the present embodiment, the die
Since the depth of the raw material filling hole 13a of 13 is shortened as compared with the conventional transverse magnetic field type magnetic field pressing device 8 (see FIG. 4), the size of the pressing die 13 and the moving stroke of the upper punch 18 are reduced. As a result, the entire device is downsized, the equipment cost is reduced, and the productivity is improved.

In this embodiment, the case of compression molding a rare earth cobalt magnetic material has been described, but the magnetic field pressing apparatus of the present invention is not limited to this. For example, even if ferrite is used as a raw material, it may be preferable to apply a transverse magnetic field orthogonal to the compression direction depending on the shape to be formed. In such a case, the magnetic field pressing device of the present invention is naturally applied. The second magnetic field generating means for applying a longitudinal magnetic field to the die 13 is not limited to the longitudinal magnetic field generating coil 23, and a permanent magnet may be moved closer to or away from the die 13 as required.

[Effects of the Invention] As described above, in the present invention, the raw material powder is densely packed in the compression direction by the magnetic field in the same direction as the compression direction of the punch pressed by the second magnetic field generating means. Therefore, the filling depth of the raw material powder is shortened and the die is downsized, and the stroke amount required to compress the raw material powder of the punch is also reduced, resulting in downsizing of the device and, as a result, the equipment of the device. The cost could be reduced significantly.

Even if the residual magnetic field of the magnetic field orthogonal to the punch compression direction remains in the die due to the magnetic field applied to the die by the first magnetic field generating means, the raw material powder is bridged by the magnetic field applied to the die by the second magnetic field generating means. Since the die is efficiently filled without doing so, the productivity can be improved. Further, since the packing density of the raw material powder is improved, it is possible to obtain a molded product having no internal defects and a high molding density.

[Brief description of drawings]

FIG. 1 is a front view of a magnetic field pressing apparatus according to an embodiment of the present invention,
FIG. 2 is an enlarged view of the lower part of the die in one embodiment of the present invention,
FIG. 3 is a schematic view of a conventional vertical magnetic field type magnetic field pressing apparatus, and FIG. 4 is a schematic view of a conventional horizontal magnetic field type magnetic field pressing apparatus. 13 …… die, 17a …… lower punch, 18 …… upper punch, 20…
... horizontal magnetic field generating means (first magnetic field generating means), 23 ... vertical magnetic field generating coil (second magnetic field generating means), 24 ... raw material powder.

Claims (1)

[Scope of utility model registration request] 1. A die for filling the raw material powder, and a punch for compressing the raw material powder filled in the die,
The tool comprises first magnetic field generating means for applying a magnetic field to the die in two directions orthogonal to the punch compression direction, and second magnetic field generating means for applying a magnetic field to the die in the same direction as the punch compression direction. A magnetic field press device.