JPH09165602A - Method for molding ring magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to rapidly and sufficiently pack the magnetic powder in a feeder box into a molding space by utilizing magnetic attraction force. SOLUTION: The feeder box 5 housing the magnetic powder 6 is moved onto the annular molding space 4 and is brought to a standstill. At least the head part of a lower punch 3A is then projected into the feeder box 5 to magnetically attract the magnetic powder to the lower punch 3A. The lower punch 3A is lowered to a prescribed position and, after the feeder box 5 is retreated, the magnetic powder 6 in the molding space 4 is compression molded on the lower punch 3A by an upper punch 8A magnetized to the same polarity as the polarity of the lower punch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring magnet molding method for molding a ring magnet having radial anisotropy from magnetic powder.

[0002]

2. Description of the Related Art Conventionally, as a method of supplying magnetic powder to a molding space, which is carried out when molding an anisotropic ring magnet, those shown in FIGS. 6 to 8 are widely known. First,
In the method shown in FIG. 6, a bottom-open feeder box 5 containing magnetic powder 6 is moved onto a ring-shaped molding space 4 formed with a lower core 2 and a lower punch 3 in a die 1, and this is further moved. This is a method in which the magnetic powder is fed into the molding space 4 by its own weight by shaking it left and right.

In the method shown in FIG. 7, a feeder box 5 containing magnetic powder in the ring-shaped molding space 4 is used.
Is positioned, and then the die 1 is vibrated or swung in the horizontal direction to feed the magnetic powder into the molding space 4 by its own weight.

Further, in the method shown in FIG. 8, after the feeder box 5 containing the magnetic powder is positioned on the molding space 4, the lower core 2 is vibrated in the vertical direction so that the magnetic powder is molded by its own weight. It is a method of supplying powder to the inside of 4.

When the powder feeding into the molding space 4 is completed by any of these methods, the feeder box 5 is subsequently retracted, and then the powder feeding into the molding space 4 is performed. The upper core 7 and the upper punch 8 slidably attached to the upper core 7 are arranged.

Further, the upper coil 9 and the lower coil 1 are arranged so as to be close to the upper core 7 and the lower core 2, respectively.
By arranging 0, an electric current is passed through each of these coils 9 and 10.

As a result, magnetic flux passes through the upper core 7 and the lower core 2 in the direction shown by the arrow in FIG.
This magnetic flux passes through the molding space 4 and the die 1. As a result, the magnetic powder 6 in the molding space 4 is oriented in the magnetic field direction.

Therefore, in this state, the upper punch 8 is lowered as shown in FIG. 10 to compress the magnetic powder 6 in the molding space 4 and shut off the current to the coils 9 and 10. Then, a current of opposite polarity is temporarily passed again for demagnetization, and thereafter, the upper punch 8 and the upper core 7 are moved up, and the lower punch 3 is moved up. Take out.

[0009]

However, in the conventional molding method for the ring magnet, each of the powder feeding methods is a method in which the magnetic powder 6 is naturally dropped into the molding space 4 by its own weight. However, there has been a problem that the filling rate in each part in the molding space 4 is biased and the density of the molded product obtained by pressure molding becomes uneven.

In particular, when the magnetic powder 6 has a high humidity and has an adhesive property, or when the ring-shaped molding space 4 is narrow, the above-mentioned problems are remarkable.

Further, as shown in FIG. 6, in the method of feeding powder while shaking the feeder box 5, the shaking time is used, and in the method of horizontally shaking the die 1 as shown in FIG. As shown in FIG. 8, in the method of vibrating the core 2 in the vertical direction, the vibrating time is relatively long, and as a result, the upper punch 8 is subsequently lowered and a magnetic field is applied by the coils 9 and 10. After that, there was a problem that one cycle of the molding process of compression-molding the magnetic powder 6 with the upper punch takes a long time.

The present invention solves the above-mentioned conventional problems, and the magnetic powder in the feeder box is removed even if it is a magnetic powder having a high humidity adhesive property or the molding space is narrow. By using magnetic attraction,
An object of the present invention is to provide a method for molding a ring magnet, which can be rapidly and sufficiently filled into the molding space and can simultaneously perform radial orientation with respect to magnetic powder.

[0013]

The ring magnet according to the present invention is molded by a feeder containing magnetic powder in a ring-shaped molding space formed in a die together with a lower core and a lower punch magnetized in the radial direction. After the box is moved and stopped, at least the head of the lower punch is projected into the feeder box to magnetically attract the magnetic powder to the lower punch, and the lower punch is lowered to a predetermined position to move the feeder. After the box is retracted, the magnetic powder in the molding space is magnetized on the lower punch so as to be magnetized to have the same polarity as that of the upper punch, and compression molding is performed by lowering the upper punch.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 are explanatory views showing a compression molding procedure of a ring magnet according to the present invention. In the figure, 2A is a non-magnetic lower core, 1A is a non-magnetic die,
3A and 8A are a lower punch and an upper punch which are magnetized, respectively. In each of these drawings, the same components as those described with reference to FIGS. 5 to 9 are designated by the same reference numerals, and duplicate description thereof will be omitted.

First, before performing the forming operation, the upper punch 8A and the lower punch 3A made of a ferromagnetic material are magnetized in the radial direction. At this time, it is necessary to make the magnetic polarities of the punches 8A and 3A equal, for example, the upper punch 8A.
If the inner peripheral side of the lower punch 3A has the N polarity, the inner peripheral side of the lower punch 3A is also magnetized to the N polarity.

Next, the feeder box 5 having the lower bottom opening containing the magnetic powder 6 is moved into the ring-shaped molding space 4 formed in the die 1A together with the lower core 2A and the lower punch 3A, as shown in FIG. Stop as shown.

Next, only the lower punch 3A is raised by a predetermined amount with respect to the lower core 2A, and the head of the lower punch 3A is projected into the feeder box as shown in FIG.
A large amount of magnetic powder 6 is placed and adsorbed on the upper surface and the outer peripheral surface of A by utilizing the magnetic adsorption force.

As a result, the magnetic powder 6 is evenly placed and adsorbed on the lower punch 2A as compared with the case where the magnetic powder 6 is naturally dropped, and at the same time, the magnetic powder 6 is oriented in the radial direction.

Subsequently, the lower punch 2A on which the magnetic powder 6 is placed and attracted in this way is lowered and stopped at a predetermined position, and then the feeder box 5 is placed on the molding space 4 filled with the magnetic powder 6. Then, it is scraped off and retracted as shown in FIG.

Then, this time, the upper punch 8A is lowered to lower the tip of the upper punch 8A into the molding space 4, and the magnetic powder 6 in the molding space 4 is compression-molded into an oriented state. After this, the upper punch 8A is raised and the lower punch 3A is moved to the lower core 2A.
The ring magnet 11 formed by raising
Can be taken out.

Therefore, in this method, the efficiency of filling the magnetic powder 6 into the molding space 4 is greatly improved, and the molding cycle time of the ring magnet is significantly shortened.

In particular, by utilizing the magnetic attraction force of the lower punch 3A, the filling rate of the magnetic powder 6 in the molding space 4 becomes uniform and sufficient, and the density deviation is eliminated, so that the ring having stable magnetic characteristics is obtained. Mass production of magnets becomes possible.

When powder is supplied by the magnetic attraction, the magnetic powder 6 is simultaneously arranged in the radial direction by the leakage magnetic flux B generated between the inner and outer peripheral surfaces of the upper end of the lower punch 3A, as shown in FIG. It

[0024]

As described above, according to the present invention, the feeder box containing the magnetic powder is moved into the ring-shaped molding space formed in the die together with the lower core and the lower punch magnetized in the radial direction. And let it rest,
At least the head of the lower punch is projected into the feeder box, magnetic powder is magnetically attracted to the lower punch, the lower punch is lowered to a predetermined position to retract the feeder box, and then the molding space is formed. Since the magnetic powder inside is magnetized to the same polarity on the lower punch and is pressed and molded by lowering the upper punch, even if it is a magnetic powder with high humidity stickiness or if the molding space is narrow. Even if there is, the magnetic powder in the feeder box can be rapidly and sufficiently filled into the molding space by using magnetic attraction, and the radial orientation with respect to the magnetic powder can be simultaneously achieved.

In this way, the effect of significantly shortening the molding cycle time of the ring magnet and producing a high-quality ring magnet with stable magnetic characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a procedure for molding a ring magnet according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a molding procedure of the ring magnet following FIG.

FIG. 3 is an explanatory diagram showing a procedure for molding a ring magnet following FIG.

FIG. 4 is an explanatory view showing a procedure for molding a ring magnet following FIG.

FIG. 5 is an explanatory diagram showing a state of generation of leakage magnetic flux in the lower punch of the present invention.

FIG. 6 is an explanatory view showing a procedure for filling magnetic powder in a conventional ring magnet molding method.

FIG. 7 is an explanatory diagram showing another conventional procedure for filling magnetic powder.

FIG. 8 is an explanatory diagram showing another conventional filling procedure of magnetic powder.

FIG. 9 is an explanatory view showing a procedure for forming a conventional ring magnet.

FIG. 10 is an explanatory view showing the procedure for forming the ring magnet, which is subsequent to FIG. 9;

[Explanation of symbols]

 1A Die 2A Lower core 3A Lower punch 4 Molding space 5 Feeder box 6 Magnetic powder 8A Upper punch

Claims (1)

[Claims] 1. A feeder box containing magnetic powder is moved into a ring-shaped forming space formed with a lower core and a lower punch magnetized in the radial direction in a die, and the feeder box is allowed to stand still. At least the head is projected into the feeder box, the magnetic powder is magnetically attracted to the lower punch, the lower punch is lowered to a predetermined position to retract the feeder box, and then the magnetic powder in the molding space. A ring magnet is formed on the lower punch by compression molding by lowering the upper punch magnetized to the same polarity as the upper punch.