JPH09225694A - Ring magnet forming device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a strong oriented magnetic field and demagnetizing field to a magnetic powder body and formed body by electrically energizing for a short time in spite of a small size magnet. SOLUTION: This device is provided with a lower core 4 which is inserted into a lower punch 2 so as to be vertically movable and forms a ring shaped forming space 11 in a mold 1 with the lower punch 2, a ring shaped electromagnet 21 which is provided with a lower end side magnetic pole 24 abutting to the upper surface of the mold 1, and a upper punch 8A which is inserted into a hollow part 28 of the electromagnet 21 to go in and out freely and compacts the magnetic powder body P in the forming space 11 with a lower non-magnetic member 26 and makes an upper magnetic member 27 abutt to the inner peripheral side magnetic pole 30 of the electromagnet 21. The upper core 7 is inserted into the upper punch 8A so as to form a magnetic path of the electromagnet 21 with the lower core 4, the mold 1 and the magnetic member 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring magnet forming apparatus and method for forming a radially anisotropic ring magnet from magnetic powder.

[0002]

2. Description of the Related Art As a conventional ring magnet molding apparatus, for example, one shown in FIG. 6 is known. The lower ram 3 has the lower punch 2 inserted into the mold 1 and the lower ram 3 is inserted into the lower ram 3 so as to be movable up and down. Forming the lower core 4
And

The above-mentioned mold 1 is installed in a yoke 5 forming a part of a magnetic path, and an upper core 7 is inserted into an upper ram 6 arranged on the mold 1 so as to be able to move up and down. I have. Reference numeral 8 denotes an upper punch integrated with the upper ram 6.

Further, a lower magnetizing coil 9 is arranged around the lower ram 3, and an upper magnetizing coil 10 is arranged around the upper ram 6.

Next, the operation of the ring magnet forming apparatus having such a configuration will be described. First, a shoe box containing, for example, magnetic powder is slid over the upper surface of the mold 1 and the yoke 5 which is continuous with the mold 1, and the magnetic powder is dropped and filled into the molding space 11.

Next, the upper ram 6 is lowered, and the upper punch 8
At the position shown in the figure slightly protruding into the molding space 11 and at the position where the upper core 7 is in contact with the lower core 4, the lowering of the upper ram 6 is stopped.

Therefore, the upper magnetizing coil 10 and the lower magnetizing coil 9 are energized so as to have mutually repelling polarities. In this energized state, the upper ram 6 is lowered again, and the upper punch 8 forms The magnetic powder is pressed until a predetermined pressure is reached.

At the end of the pressurization, the energization is stopped, and then the energization in the opposite direction to that of the coils 9 and 10 is performed to demagnetize the compact made of magnetic powder. Thereafter, the mold 1 is lowered, the upper ram 6 is raised, the lower core 4 is lowered, and then the lower punch 2 is raised to take out the molded body.

In this manner, the lower magnetizing coil 9 and the upper magnetizing coil 10 which are large-diameter air-core coils are connected to the lower ram 3.
And the upper ram 6 is set to be a magnetic core, respectively,
Moreover, the magnetic powder is oriented in the radial direction by radially flowing repulsive magnetic fluxes from the cores 4 and 7 toward the mold 1, thereby producing a radially anisotropic ring magnet.

[0010]

However, in such a conventional ring magnet forming apparatus, since the lower magnetized coil 9 and the upper magnetized coil 10 have a large diameter, each of the rams 3 and 6 has a magnetic circuit. Therefore, it is necessary to considerably increase the magnetomotive force of each of the coils 9 and 10.

For this reason, in addition to increasing the size of the equipment, the cost is increased, and it takes a long time to rise and fall the energization time for magnetization for orientation and demagnetization, and for magnetization and demagnetization. Since it is necessary to provide an energization pause time (exceeding the time constant due to the self-inductance of the coil) between
As a result, the time required to form one ring magnet is
For example, there is a problem that it takes 25 to 45 seconds.

The present invention has been made in order to solve the above-mentioned conventional problems, and can apply a strong orientation magnetic field to the magnetic powder in a concentrated and efficient manner while suppressing the energization time and the energization current. Thus, it is an object of the present invention to provide a ring magnet molding apparatus and a molding method capable of manufacturing a desired ring magnet at low cost with a small facility.

[0013]

According to a first aspect of the present invention, there is provided a ring magnet forming apparatus, wherein a non-magnetic lower punch which is inserted into and out of a die and a lower punch which is vertically movable are inserted into the lower punch. A lower core that forms a ring-shaped molding space in the mold together with the lower punch, and a lower-end magnetic pole that is movable on the mold and contacts the upper surface of the mold. The electromagnet and the magnetic powder which is inserted into the hollow portion of the electromagnet so as to be able to move in and out and the lower non-magnetic member fills the molding space with the magnetic powder, and the upper magnetic member is provided on the inner peripheral side of the electromagnet. An upper punch capable of contacting the magnetic pole is provided, and the upper core is inserted into the upper punch so as to form the magnetic path of the electromagnet together with the lower core, the die and the magnetic members of the upper punch. .

According to a second aspect of the present invention, there is provided a method for molding a ring magnet, wherein magnetic powder is filled in a molding space formed in a mold by a lower punch and a lower core that can move up and down in the lower punch. Move the ring-shaped electromagnet onto the mold,
After contacting the magnetic pole on the lower end side with the upper surface of the mold, an upper core is inserted into the hollow portion of the electromagnet, and an upper punch having an upper part made of a magnetic member and a lower part made of a non-magnetic member is inserted. When the lower end of the non-magnetic member reaches the upper surface of the molding space, it is temporarily stopped, and subsequently, the electromagnet is energized to apply a magnetic field to the magnetic powder, and then the lower end of the non-magnetic member is The magnetic powder is compressed, and in this state, the electromagnet is energized to apply a demagnetization mode magnetic field to the magnetic powder.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view specifically showing a ring magnet molding apparatus of the present invention. Here, parts that have substantially the same configuration as in FIG. 6 are assigned the same reference numerals, and duplicate descriptions thereof are omitted. I am doing it.

In this embodiment, the conventional lower magnetizing coil 9 and upper magnetizing coil 10 are omitted, and a new slider is newly moved to the upper surface of the mold 1 for orientation to magnetic powder described later. A small ring-shaped electromagnet 21 is provided as a magnetizer that gives a magnetic field.

This ring-shaped electromagnet 21 has a ring core 2
2 is provided with a coil 23 on the inner peripheral side, and when the coil 23 moves to and is located on the mold 1, the lower end side magnetic pole 24 of the ring core 22 closely contacts the upper surface of the mold 1. Has become. In addition, 25 is the electromagnet 21 and the mold 1
It is a guide rod for moving it up and down.

On the other hand, 8A is a cylindrical upper punch, the lower half of which is made up of a non-magnetic member 26 and the upper half of which is made up of a magnetic member 27.
Is substantially equal to the inner diameter of the hollow portion 28.

When the upper punch 8A is inserted into the hollow portion 28, the magnetic member 27 moves the electromagnet 2
The inner peripheral magnetic pole 30 of the ring core 22 of No. 1 can be closely contacted.

The upper core 7 is placed in the upper punch 8A.
Is supported by the spring member 29, and the tip end (lower end)
Can be moved in and out of the open end of the upper punch 8A. Further, the upper core 7 is made of a magnetic material, and the outer periphery of the upper portion thereof is in close contact with the magnetic member 27, and these form a magnetic path together with the lower core 4, the mold 1 and the ring core 22.

The upper punch 8A is supported by an upper ram (not shown) not shown, and the lower punch 2 is supported by a lower ram (not shown).

Further, the die 1 forms, together with the lower punch 2 and the lower core 4, a ring-shaped molding space 11 for containing the magnetic powder.

Next, a method of molding the ring magnet by the molding apparatus having the above-mentioned structure will be described. First, by sliding a shoe box (not shown) onto the die 1, the magnetic powder P contained in the shoe box is
The inside of the molding space 11 is filled, and then the shoe box is retracted from the mold 1.

Next, the electromagnet 21 is slid onto the mold 1 so that the lower end surface of the magnetic pole 24 on the lower end side of the ring core 22 is brought into contact with the upper surface of the mold 1, and then the upper ram is lowered.
The upper punch 8A containing the upper core 7 is attached to the electromagnet 21.
Inserted in the hollow portion 28.

Then, when the lower end surface of the upper punch 8A, that is, the lower end surface of the non-magnetic member 26 reaches the upper surface of the molding space 11 as shown in FIG.
Is partially stopped and the coil 23 of the electromagnet 21 is energized.

Therefore, the magnetic flux generated by the coil 23 is shown by an arrow in FIG. 2 along the magnetic path formed by the ring core 22, the magnetic member 27 of the upper punch 8A, the upper core 7, the magnetic powder P and the die 1. And the magnetic powder P in the molding space 11 is oriented in the radial direction within the magnetic field.

In the present invention, although the electromagnet 21 is small as described above, the lower magnetic pole 24 is brought into close contact with the upper surface of the mold 1, and the inner magnetic pole 30 is the upper punch magnetic member 27.
Therefore, even if the power applied to the coil 23 is small, the magnetic field can be shortened and a large magnetic field can be applied to the magnetic powder. Done efficiently.

Since the magnetic powder P is narrowed between the non-magnetic member 26 of the upper punch 8A and the non-magnetic lower punch 2, the magnetic path is narrowed here and the magnetic flux is Since it concentrates on the magnetic powder P portion, an extremely strong orientation magnetic field can be applied to this magnetic powder P even if the above-mentioned energization is performed for a short time.

Next, after applying the orientation magnetic field, the upper punch 8A is further lowered, and the lower end portion (lower end portion of the non-magnetic member 26) is press-fitted into the molding space 11 as shown in FIG. Then, the magnetic powder P therein is compressed.

While maintaining the compressed state, electric power is applied to the coil 23 to generate a static magnetic field or a pulse magnetic field in the opposite direction to the magnetic path, and the shaped magnetic powder is produced. The molded body Q made of P is demagnetized.

Next, as shown in FIG. 4, the die 1 is lowered along with the lowering of the lower ram to open the outer periphery of the molded body Q, and subsequently, the upper punch 8A is moved as shown in FIG. By pulling up from the hollow portion 28 of the electromagnet 21, the molded body Q placed on the lower punch 2 can be taken out.

In this way, the small electromagnet 21 is slid onto the mold 1 separately from the operation of the upper ram, and the lower magnetic pole 2
4 and die 1 and inner magnetic pole 30 and upper punch 8
By joining the magnetic member 27 of A to the magnetic member 27, the magnetization and demagnetization of the magnetic powder P and the molded body Q of the magnetic powder P can be efficiently performed while suppressing the loss. Therefore, the manufacturing efficiency and the manufacturing cost of the ring magnet are significantly improved, the cycle time of molding is significantly shortened as compared with the conventional method, and high-speed molding and manufacturing are possible.

Further, in the above-mentioned embodiment, the molding device for a single-piece ring magnet has been described, but the double-piece or more molding can be efficiently performed by downsizing the electromagnet.

As described above, in the ring magnet molding method according to the present invention, a strong magnetic field is generated by applying a strong magnetic field even by instantaneous energization, for example, pulse energization, due to the synergistic effect of magnetic field concentration and magnetic resistance reduction. It is possible to efficiently affect P and the molded body Q thereof, and this can be realized with a simple and inexpensive structure and method.

Further, by applying the pulse current, the degree of orientation by the pulse magnetic field is improved, a high-performance ring magnet can be obtained, and magnetic field shaping can be performed with higher efficiency than in the conventional case.

Further, in the molding method of the present invention, when the molded product is demagnetized, the mold 1 is also demagnetized at the same time, so that the magnetic powder P
The bridging phenomenon at the time of powder feeding is eliminated, and therefore powder feeding becomes easy.

Further, since the work of applying the magnetic field and the compression molding of the magnetic powder P are carried out in independent steps with the position of the electromagnet 21 fixed, the control of the mutual operation timing becomes easy. In addition to speeding up the molding operation, the equipment cost can be reduced.

[0038]

As described above, according to the first aspect of the present invention, the non-magnetic lower punch which is inserted in and out of the die and the lower punch which is vertically movable in the lower punch together with the lower punch. A lower core that forms a ring-shaped molding space in the mold,
A ring-shaped electromagnet having a magnetic pole on the lower end side that is movable on the mold and is in contact with the upper surface of the mold, and a non-magnetic member at the bottom that is inserted into and retractable from the hollow portion of the electromagnet. By compression molding the magnetic powder filled in the molding space, and by providing an upper punch that allows the upper magnetic member to contact the inner magnetic pole of the electromagnet, the lower core, the mold, and Since the upper core is inserted into the upper punch so as to form the magnetic path of the electromagnet together with the magnetic member of the upper punch, the magnetic resistance is suppressed to a small value despite the small electromagnet, and the magnetic powder is reduced. By narrowing the magnetic path in the body part and further shortening the magnetic path length, a strong orientation magnetic field and demagnetizing magnetic field can be applied to the magnetic powder and the molded body by short-time energization, and molding with good quality Goods quickly and reliably There is an effect that can Rukoto.

According to the second aspect of the invention, the magnetic powder is filled in the molding space formed in the mold by the lower punch and the lower core which can be raised and lowered in the lower punch, and the magnetic powder is filled in the molding space. After moving the ring-shaped electromagnet to the upper surface and bringing the lower end side magnetic pole thereof into contact with the mold, the upper core is inserted into the hollow portion of the electromagnet, and the upper part is made of a magnetic member and the lower part is After inserting an upper punch made of a non-magnetic member and temporarily stopping it when the lower end of the non-magnetic member reaches the upper surface of the molding space, and subsequently applying current to the electromagnet to apply a magnetic field to the magnetic powder. The magnetic powder is compressed at the lower end of the non-magnetic member, and the electromagnet is energized in this state to apply a magnetic field in the demagnetization mode to the magnetic powder. To reduce the rise time and fall time of the energization time In addition, it is can be reduced even downtime between the magnetization and demagnetization, thus, the cycle time for molding one molded article remarkably be shortened, the effect is obtained that attained the product cost.

Further, each operation of applying a magnetic field to the magnetic powder or the compact and performing compression compaction by the upper punch can be independently realized at different timings with the position of the electromagnet fixed.
As a result, the effects of facilitating the design of the system for this control and reducing the cost of the equipment can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a ring magnet forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of orientational excitation of magnetic powder by the molding apparatus shown in FIG.

FIG. 3 is an explanatory view showing a compression molding state of magnetic powder by the molding apparatus shown in FIG.

FIG. 4 is an explanatory diagram showing a state in which the mold is lowered by the molding apparatus shown in FIG. 1 after completion of molding.

5A and 5B are explanatory views showing an upper punch rising state by the forming apparatus shown in FIG.

FIG. 6 is a cross-sectional view showing a conventional ring magnet molding apparatus.

[Explanation of symbols]

 1 Mold 2 Lower Punch 4 Lower Core 7 Upper Core 8A Upper Punch 11 Molding Space 21 Electromagnet 24 Lower Side Magnetic Pole 26 Non-Magnetic Member 27 Magnetic Member 28 Hollow Part 30 Inner Circumferential Side Magnetic P P Magnetic Powder Q Molded Body

Claims (2)

[Claims] 1. A non-magnetic lower punch that is inserted into and removed from a mold, and a lower part that is vertically inserted into the lower punch and forms a ring-shaped molding space in the mold together with the lower punch. A core, a ring-shaped electromagnet that is movable on the mold, and has a lower-side magnetic pole that is in contact with the upper surface of the mold, and a ring-shaped electromagnet that can be inserted into and removed from the hollow portion of the electromagnet. A magnetic powder filled in the molding space with a non-magnetic member is compression-molded, and an upper punch that allows the upper magnetic member to contact the inner magnetic pole of the electromagnet, the lower core, the mold, and A ring magnet molding apparatus comprising: a magnetic member of the upper punch; and an upper core inserted into the upper punch so as to form a magnetic path of the electromagnet. 2. A magnetic powder is filled in a molding space formed in a mold by a lower punch and a lower core that can move up and down in the lower punch, and a ring-shaped electromagnet is moved onto the mold. Then, after contacting the magnetic pole on the lower end side with the upper surface of the mold, an upper core is inserted into the hollow part of the electromagnet, and an upper punch having a magnetic member at the upper part and a non-magnetic member at the lower part is formed. When the lower end of the non-magnetic member has been inserted, it is temporarily stopped when the lower end of the non-magnetic member reaches the upper surface of the molding space, and subsequently the electromagnet is energized to apply a magnetic field to the magnetic powder, and then the lower end of the non-magnetic member is applied. A method for molding a ring magnet, comprising: compressing the magnetic powder, and energizing the electromagnet in this state to apply a demagnetization mode magnetic field to the magnetic powder.