JPS60220919A - Manufacture of ringed permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a thin ringed permanent magnet by a method wherein, when the ringed permanent magnet having a magnetic anisotropy is made in a magnetic field by an extrusion molding method, a tape made of resin-bonded rare earth magnet power is pushed out in a spiral form and after the tape is wound around on a ringed mandrel, the tape is cut in a ringed form along with the mandrel. CONSTITUTION:A hopper 1 is provided on one end of the upper part of a cylinder 2 provided with heaters 3 wound around on its outer periphery, a tapered barrel part 5 is provided on an aperture on the other end of the upper part and a screw 4 is housed in the interior of the cyliner 2. Moreover, a magnetic circuit 6 and a demagnetizing circuit 13, between both of which a cooling die 11 and a water cooling pipe 12 have been held, are provided on the side of the barrel part 5 and magnetic field coils 7 and 8, on which a magnetic line of force 9 generates through a gap 10, are arranged in the interior of the die 11. An extrusion molding device is constituted in such a way and magnet powder is thrown into the cylinder 2 from the hopper 1. The magnet powder is made to pass through the interior of the die 11 by the screw 4, is pushed out from a corrective die 14 being surrounded with a heating heater 15 and is formed into a tape of a spiral form. After that, the tape is wound around on a ringed mandrel and is ringed in a prescribed length along with the mandrel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a thermoplastic resin bonded rare earth radially anisotropic permanent magnet by extrusion molding in a magnetic field.

[Prior art]

Conventional rare earth permanent magnets that use thermoplastic resin as a binding material are
Manufactured using an injection molding method, they can be roughly divided into isotropic magnets and anisotropic magnets that have magnetic performance added only in a specific direction. Cylindrical radially anisotropic permanent magnets made of bamboo with radial magnetic anisotropy are widely used as rotors in small motors, etc. by applying multipolar magnetization to the outer circumferential surface.

However, most of the cylindrical permanent magnets are short in length compared to the inner diameter, and have a wall thickness of one group or more, which is limited in size. Therefore, a method of manufacturing cylindrical radially anisotropic permanent magnets by extrusion molding has been invented, but none of these methods have been put to practical use. JP-A No. 53-43897 discloses a method in which rare earth permanent magnets are manufactured using thermoplastic resin and then wound into a tape shape in multiple layers to create a roll. Since the cost is extremely high, it is difficult to put into practical use processes that increase costs, such as winding multiple layers, and cutting the sheet after forming it into a sheet to a predetermined thickness is inefficient, resulting in cracks and cracks during winding. There was a problem that magnetic anisotropy could not be added by the calendaring method when rare earth magnet particles were used.

[Purpose] The present invention is intended to solve such problems, and its purpose is to create a thin ring-shaped radial whose length is longer than its inner diameter using resin-bonded rare earth magnet powder. The purpose of the present invention is to provide a technology for manufacturing anisotropic permanent magnets.

〔overview〕

The method for producing a ring-shaped permanent magnet of the present invention uses a mixture of rare earth magnet powder and thermoplastic resin, and uses an extrusion molding device in a magnetic field to form a spiral shape with a predetermined thickness and magnetic anisotropy. A ring-shaped permanent magnet is manufactured by extruding a tape, winding the tape around a ring-shaped mandrel, and cutting the tape into a predetermined length.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

(Example 1) This example is shown in FIG. 1(A). The mixture of rare earth magnet powder and thermoplastic resin put into the hopper 1 is heated to a predetermined temperature by the heater 3 in the cylinder 2, kneaded by the rotation of the screw 4, and extruded into the Taber bar sill part 5. It will be done. Next, the rare earth magnet powder in the mixed material is oriented in the thinner direction at right angles to the extrusion direction by the magnetic field generated in the magnetic circuit B which also serves as a die. As shown in FIG. 1(B), this structure has a shape in which two E-shapes are placed vertically facing each other, and the middle part has a taper and a gap 10 is provided between it and the other part. Magnetic field coils 7.8 on both sides
is set, and magnetic lines of force 9 flow in the direction of the arrows due to the direct current flowing from a separate direct current power supply device to generate a magnetic field in the gap 10.

Usually, the gap is in the range of 10 to 20 mm, depending on the thickness of the tape-shaped magnet to be molded, and a molding die is inserted into this gap. The oriented crosstalk is cooled and solidified by flowing water through the water-cooled pipe 12 wound around the cooling die 11.

Due to the residual magnetic field caused by the oriented magnetic field, the magnetization balance will be disrupted when the molded products are attracted to each other in the subsequent process or multi-pole magnetized in a ring shape, so demagnetization is performed using the demagnetization circuit 13. . The degaussing circuit has the same structure as that in Figure 1 CB), but by reversing the direction of the lightning current flowing through the magnetic field coil 7°8, the lines of magnetic force 9 generated are in the opposite direction, thereby demagnetizing. Through the above steps, a resin-bonded rare earth anisotropic permanent magnet with magnetic anisotropy added perpendicularly to the thin direction of the tape-shaped permanent magnet and whose surface magnetic flux density is almost zero due to demagnetization is formed. Next, the straightening die 14 is heated to a predetermined temperature by the heating heater 15, passed through the die and cooled, and is twisted and rolled into a spiral shape as shown in FIG. Fix it with epoxy adhesive and cut it into rings of a predetermined length to make a ring-shaped permanent magnet. As described above, a straightening die was attached to the magnetic field extrusion molding apparatus, and the tape shape was transformed into a spiral shape, and then into a ring shape. In detail, rare earth magnet powder can be expressed in the general formula as sm(000,0er
r”O, Og Fed, 22 Zro, Ou) 8.3
This alloy is a 2-17 rare earth intermetallic compound alloy consisting of No. 11, and this alloy is made into magnetic powder with a particle size of 2 to 80 microns using a ball mill.

To 65 volumes of powder thus produced, 15 volumes of thermoplastic resin nylon 6 and 20 volumes of nylon 12 were added.
The mixture was mixed in a volumetric mixer and charged into an extrusion molding device in a magnetic field through hopper 1.

The appropriate volume ratio of the magnet powder is 40 to 75, and the appropriate range is nylon 6 pieces PR% 10 to 35, and nylon 12 pieces PR%. Cylinder 2 is kept at about 300°C by a heater, and the mixture is kneaded by a screw until it reaches a tapered bar sill part made of non-magnetic material, and then a die part made of magnetic material fixed in the gap of a magnetic circuit made of magnetic material. The rare earth magnet powder in the mixture passes through the mixture while being oriented by the magnetic field lines caused by the direct current flowing through the magnetic field coil.

The dimensions of the die part are 0.5 to 21 mm, which is the molding thickness.
EIl, the width of the gap is 2 to 15 mm, the thickness of the die itself is 5 to 20 + wings, and the width is within the appropriate range to be 2 to 10 times larger than the width of the gap, but in this example. The gap is 0.8 dragon, the gap width is 811I11, the die thickness is 1
The width was 12 dragons, and the gap part of the magnetic circuit was also sized to match the die part. Lightning and current were passed through the magnetic field coil, and the generated magnetic field was set to 15,000 (Oe).

The relationship between the strength of the magnetic field generated in the dice and the current is shown in Figure 3. Next, when it passes through the cooling die, it is cooled and solidified by flowing water through a water-cooled pipe, and then passes through a magnetic circuit and a degaussing circuit with the same specifications as the die section, so that the current flows through the magnetic field coil from the opposite direction. Magnetic lines of force act in the opposite direction to the direction during orientation, resulting in demagnetization. The magnetic field coil is the same as above, but is it a current? By controlling it, a demagnetizing magnetic field is created. Next, it enters a straightening die heated to a temperature of 1so-2ooa by a heater, and is rolled into a ball while being twisted. Using this method, a spiral magnet with an inner diameter of approximately 17 mm and a length of 60,011 m was formed. Outer diameter: 16mm, length: 112mm
Epoxy resin was applied to a ring-shaped mandrel with an outer diameter of 0 mm, and the magnet was wound while being adhered, heated at 80° C. for 1 hour, and then cut with a cutter to obtain a rotor magnet with an outer diameter of 17.6 mm and a length of 18 mm.

On the other hand, the rare earth magnet powder and nylon 6 used in this example
．． A mixture of 12 and
A rotor magnet similar to that of this example was obtained by adhesively fixing it to a ring-shaped mandrel. When a double-ended magnet was magnetized with two poles inside and outside and the surface magnetic flux density was measured using a Gaune meter and a Hall probe, the magnet body manufactured by the method of the present invention was approximately 2100 (
G), and isotropic by conventional extrusion molding method is about 90
It showed 0 (G).

(Example 2) Using the same rare earth magnet mixture as in Example 1 and using the same method, the die gap was set to 0.5 inches, and the width of the gap was
Molding was carried out using 5n. The orientation magnetic field of the gap was set to 15,000 (Oe), the same as in Example 1. Furthermore, the dimensions of the gap portion of the magnetic circuit remain unchanged. Replace the straightening die, form a spiral magnet with an outer diameter of 8mm and a length of 150mm, wrap and glue around a ring-shaped mandrel with an inner diameter of 7tm, and cut to create a rotor magnet with an outer diameter of 8mm and a length of 8''IIx. On the other hand,
Using the mixture of the rare earth magnet and nylon 6.12 used in this example, an isotropic tube of the same size was formed by extrusion molding, and a ring-shaped mandrel similar to that in the example was glued inside. A rotor magnet with an outer diameter of F3 m+111 and a length of 8 marks as in the example was obtained. When the surface magnetic flux density of a double-ended magnet was polarized (internally and externally) was measured, the magnet body manufactured by the method of the present invention showed approximately 800 (G), and was In terms of gender, it showed approximately 210 (G).

Two examples have been described above, but the cross-sectional shape of the tape to be extruded does not have to be flat, but may be the shape shown in Figure 4, or the tape can be wound in multiple strips by extremely reducing the pitch of the spirals. The rotor magnet shown in FIG. 5 can also be manufactured.

〔effect〕

As described above, according to the present invention, in a method for manufacturing a ring-shaped permanent magnet having magnetic anisotropy by an extrusion molding method in a magnetic field, thermosetting resin bonded rare earth magnet powder is used to form a tape shape. Strain it into a spiral shape to form a ring. In order to make it into a tape shape in the process of adding magnetic anisotropy,
The magnetic field is large and the magnetic particles are well oriented, allowing direct ring,
In the method of adding radial anisotropy by forming a spiral, it may not be possible to obtain an orienting magnetic field depending on the shape, but this method is particularly useful in such cases. This has the effect of producing long, thin-walled radial magnets.

In addition, thin-walled magnets are possible because the method is made into a spiral and then wrapped around a ring-shaped mandrel, and the amount of change after hardening is smaller than the method of winding a tape-shaped material around a ring-shaped mandrel, so there are fewer cracks and cracks, and the desired wall thickness can be maintained. There is no need to wrap multiple layers of thin-walled products in order to achieve a desired thickness, and the product can be formed to a predetermined thickness and then wrapped, which also has the effect of reducing costs.

[Brief explanation of the drawing]

Figures 1 and (B) show examples of molded products produced by the method of the present invention. Figure 2 shows an example of a molded product produced by the method of the present invention. Figure 3 shows the relationship between the coil current and the strength of the generated magnetic field. Figure 4 shows the relationship between the coil current and the strength of the generated magnetic field. A cross-sectional view of an embodiment according to the method of the present invention. Fig. 5 is a complete perspective view of a rotor magnet for a motor according to the method of the present invention. 1. Hopper 2. Cylinder 3. Heater 4. Screw 5. Teher barrel section 6 ...Magnetic circuit 7.8...
Magnetic field coil 9... Lines of magnetic force 10... Gap 11... Cooling die 12... Water cooling pipe 16... Demagnetizing circuit 14... Straightening die 15...
Heating heater and above Applicant Suwa Seikosha Co., Ltd. Agent Patent attorney Mogamisuji (Shio) Figure 1 Figure 2

Claims (1)

[Claims] In a method for manufacturing a ring-shaped permanent magnet with magnetic anisotropy by extrusion molding in a magnetic field, resin-bonded rare earth magnet powder is used to extrude a bi-viral tape, and the tape is wound around a ring-shaped mandrel. Attached is a method for manufacturing a ring-shaped permanent magnet, which is characterized by cutting the ring-shaped permanent magnet into rings of a predetermined length ζ.