JP4110488B2 - Method and apparatus for removing magnetic powder from molded body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for removing magnetic powder remaining on a molded body obtained by molding magnetic powder in a magnetic field, and more particularly to a magnetic powder removing method and apparatus suitable for removing magnetic powder adhered to burrs and surfaces.
[0002]
[Prior art]
In order to manufacture a rare earth magnet or a magnet with high coercive force , powder of a magnetic material is supplied to a mold, and compression molding is performed while imparting anisotropy in a magnetic field. Thereafter, the magnet is taken out after being demagnetized in the mold, but since the complete demagnetization is difficult, the compact has residual magnetism. For this reason, the spilled magnetic powder existing on the lower mold surface and the magnetic powder adsorbed on the upper mold are attracted to and adhered to the molded body. If this adhered magnetic powder is not completely removed and then passed to the subsequent process, the following problems occur, resulting in a decrease in production efficiency and the occurrence of defects.
(1) The adhering magnetic powder is baked in at the time of firing and cannot be removed unless grinding is performed, and a lot of processing time is required.
(2) Due to the adhered magnetic powder, the outer dimensions do not fit within a predetermined value, and a clogging failure occurs in the workpiece supply device of the grinding machine.
(3) The adhered magnetic powder cannot be removed by processing, resulting in a defective product.
As a method for removing the adhered magnetic powder, Japanese Patent Laid-Open No. 8-330135 discloses a molded body magnetic powder removing device. As shown in FIG. 9, first, the molded body is demagnetized by the demagnetizing coil 34 installed under the conveyor 31 that conveys the molded body 32 to remove the adhered magnetic powder, and then the gas ejector 33 is directed toward the molded body. By blowing out more gas, the remaining magnetic powder is blown away and automatically removed.
[0003]
[Problems to be solved by the invention]
However, the form of the adhering magnetic powder is not only the one attracted and adhered by the residual magnetism of the molded body as described above, but also formed by burrs generated on the die mating surface at the time of molding, by hand or at the time of ejecting plate, etc. For example, there are fixed magnetic powders that are pressure-bonded to the molded body by mechanical contact with the body. These are strongly bonded to each other through a binder blended in the magnetic powder, and cannot be completely removed by the demagnetizing coil or the gas jetting action shown in the known examples, and are manually removed. Work was left.
Accordingly, an object of the present invention is to provide a method and apparatus capable of automatically removing magnetic particles including burrs and fixed magnetic particles remaining in a molded body without manual intervention.
[0004]
[Means for Solving the Problems]
According to the method for removing magnetic particles from a molded body according to the present invention, the magnetic powder filled in the cavity of the molding machine is molded in a magnetic field and then demagnetized. after, it is characterized by removing the magnetic particles of the molded body surface by Rukoto over an alternating magnetic field. In addition, it is preferable that the maximum magnetic field strength of the pulse vibration damping magnetic field is 10 to 40 times the magnetic field strength of the alternating magnetic field. Further, the magnetic particle removing apparatus for a molded body according to the present invention demagnetizes the magnetic powder filled in the cavity of the molding machine in a magnetic field, and then removes the molded body after demagnetization from the molding machine to obtain a pulsed vibration damping magnetic field. And then applying an alternating magnetic field to remove the magnetic powder on the surface of the molded body, a first powder removing coil that generates a pulsed vibration damping magnetic field, and a second powder removing that generates an alternating magnetic field The present invention is characterized in that a transfer device for holding and transferring the molded body taken out from the molding machine to the coil, the first powder removal coil, and the second powder removal coil is provided.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 shows a first embodiment of a magnetic particle removing apparatus of the present invention.
First, the outline of the molding machine and the molding operation will be briefly described. The powder molding machine 9 includes an upper mold 10 and a lower mold 11, a push-up mold 13 that penetrates the lower mold 11, and a powder feeder 14 that slides on the surface of the lower mold 11. The cavity 12 is a space generated in the lower mold 11 when the push-up mold 13 is lowered by a predetermined amount. The molded body 8 is molded by filling the cavity 12 with magnetic powder and then lowering the upper mold 10 and compressing it in a magnetic field. The molded body 8 after molding is pushed up by the push-up mold 13 after demagnetization, and is placed on the end of the lower mold 11 by the protruding plate 15 installed at the front part of the powder feeder 14 that moves forward for powder feeding in the next cycle. Taken out by being pushed out. After the molded body 8 is extruded, the push-up die 13 is lowered, the magnetic powder is again filled in the cavity 12, and the next cycle starts.
[0006]
Next, the magnetic particle removing device will be described.
A transfer machine 1 having a movable unit 1A operable in the left-right direction in FIG. A first powder removal coil 3 is installed below the operation path of the movable unit 1A. The first powder removal coil 3 is an air-core coil in which an electric wire is wound around the outer circumference of a non-magnetic cylinder, and is connected to a power source (not shown) for applying a current via a power cable (not shown). Connected. A removal powder receiving box 5 is provided below the first powder removal coil 3.
A second powder removal coil 4 is installed below the operation path of the movable unit 1 </ b> A of the transfer machine 1 and to the right of the first powder removal coil 3. The second powder removal coil 4 is a cored coil in which an electric wire is wound around the outer periphery of the iron core, and is connected to an AC power source (not shown) via a power cable (not shown). A removal powder tray 6 is provided on the second powder removal coil 4. On the right side of the second powder removal coil 4, a molded product alignment plate 7 for placing the powdered molded product 8 is provided. The movable unit 1A is provided with a hand 2 that holds the molded body 8 so as to be movable in the vertical direction.
[0007]
The first powder removal coil 3 generates a pulsed magnetic field in which the discharge current causes a resonance phenomenon when the energy accumulated in the capacitor is discharged, and first attenuates for a while after generating a high magnetic field. FIG. 4 shows the waveform of the magnetic field generated at that time. The second powder removal coil 4 is supplied with an alternating current having a frequency converted by an inverter such as 50 Hz or 60 Hz, and generates an alternating magnetic field having a certain magnitude. FIG. 5 shows the waveform of the magnetic field generated at that time. The maximum value (b) of the magnetic field strength of the first powder removal coil 3 may be 10 to 40 times stronger than the magnetic field strength (a) of the second powder removal coil 4.
[0008]
The operation will be described below.
The transfer device 1 holds the molded body 8 taken out at the end of the lower mold 11 with the hand 2, moves the molded body 8 to the right with the movable unit 1 </ b> A, and is almost centered on the first powder removal coil 3. Transfer. After that, the first powder removal coil 3 is discharged from the capacitor to generate a magnetic field as shown in FIG. Due to the oscillating magnetic force due to the vibration of the initial pulse-like high magnetic field, a large attractive force acts on the molded body 8 while suddenly changing the direction, and the magnetic particles fixed to the burrs and the surface are crushed or peeled off. At this time, the magnetic powder separated and dropped from the molded body 8 is captured by the removed powder receiving box 5. Since this pulse magnetic field attenuates and becomes zero with the decay of the discharge current, almost no magnetism remains in the compact and the magnetic powder remaining on the compact. In addition, as shown in FIG. 2, it is desirable from the surface of energy efficiency that the molded object 8 is arrange | positioned in the part with high magnetic flux density of the center part of the 1st powder removal coil 3. As shown in FIG. Further, if it deviates from the center, a force is generated to move the molded body 8 to the center according to the density of the magnetic field lines when a magnetic field is applied, and an unbalanced load acts on the transfer device 1 and the hand 2, which is not desirable. FIG. 3 shows an example of the arrangement when a magnetic field is simultaneously applied to a plurality of molded bodies 8. Although there exists a method of arrange | positioning to the object in the center of the 1st powder removal coil 3, or arrange | positioning in series in the center, it is desirable for the molded object 8 to be settled in the air core diameter of the 1st powder removal coil 3.
[0009]
Next, the movable unit 1 </ b> A is restarted, and the compact 8 is passed over the center of the second powder removal coil 4 and transferred to the compact alignment plate 7. While the molded body 8 is passing over the second powder removal coil 4, the second powder removal coil 4 is energized to generate an alternating magnetic field due to an alternating current. The magnetic powder left on the surface of the molded body 8 jumps on the surface by the magnetic attractive force in both directions by this alternating magnetic field, the magnetic powder on the lower surface and the side surface falls as it is, and the magnetic powder on the upper surface falls off the upper surface as the molded body moves. Then, it is captured by the removal powder receiving tray 6 installed on the second powder removal coil 4. As described above, the energization of the second powder removal coil 4 is only required while the molded body 8 is present on the second powder removal coil 4, and the presence or absence of the molded body 8 is detected by a sensor (not shown) or the like. If it is determined and performed only during that time, energy is saved.
[0010]
(Embodiment 2)
FIG. 6 shows a second embodiment of the present invention.
The use of two powder removal coils is the same as in the first embodiment, except that the conveyor 20 is used to move the molded body 8 on the second separation coil. A conveyor 20 is provided adjacent to the right side of the first powder removal coil 3, and the powder removal coil 4 is installed under the belt 21 of the conveyor 20. The belt 21 is a non-magnetic mesh.
The molded body 8 gripped by the hand 2 and applied with a pulsed high magnetic field by the first powder removal coil 3 is then placed on the conveyor 20. As the belt 21 rotates, the molded body 8 moves in the traveling direction 20A, and an alternating magnetic field is applied while passing over the second powder removal coil 4. The residual magnetic powder removed by the magnetic attraction generated by the second powder removal coil 4 is captured by the powder removal tray 6 installed between the second powder removal coil 4 and the belt 21.
[0011]
(Embodiment 3)
FIG. 7 shows a third embodiment of the present invention.
The basic configuration is based on the first or second embodiment, and a gas ejector 22 is further installed on the right side of the second powder removal coil 4. High-pressure gas can be ejected from the gas ejector 22 onto the surface of the molded body 8 that has passed over the second powder removal coil 4. Thereby, even when there is a possibility that the magnetic powder may remain even with the two powder removing coils, it is possible to cope with it. FIG. 9 shows a partial detail view of the 1B cross section of the attachment portion of the gas ejector 22. Although the figure shows an example in which the gas ejector 22 is installed on the left and right surfaces with respect to the molded body 8, the same effect can be obtained even if installed in the vertical direction.
[0012]
【The invention's effect】
The present invention has the following effects.
1) Even magnetic particles that are firmly bonded to a molded body by burrs are peeled and crushed by a strong damped pulse magnetic force and then removed by alternating magnetic force, so that magnetic particles can be automatically removed without human intervention. .
2) Since the removed magnetic powder is captured on the side of the powder removal coil, there is no scattering and the surrounding environment is not deteriorated.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a magnetic powder removing apparatus according to the present invention. FIG. 2 is a view showing a desirable positional relationship between a first powder removal coil and a molded body. Fig. 4 is a diagram showing a desirable positional relationship of Fig. 4. Fig. 4 is a magnetic field waveform of a first powder removal coil. Fig. 5 is a magnetic field waveform of a second powder removal coil. Fig. 6 is another embodiment of the magnetic particle removal apparatus of the present invention. FIG. 7 is a view showing still another embodiment of the magnetic particle removing apparatus of the present invention. FIG. 8 is a view showing the relationship between the gas injector and the molded body in FIG. 7. FIG. Schematic diagram of removal device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transfer machine 2 Hand 3 1st powder removal coil 4 2nd powder removal coils 5 and 6 Removal powder receiving box 8 Molded body 9 Powder molding machine 12 Cavity 13 Push-up die 20 Conveyor 21 Belt 22 Gas ejector

Claims (3)

It was filled in a cavity of a molding machine magnetic powder to demagnetize after molding in a magnetic field, after being subjected to a pulse-like vibration damping magnetic field taken out molded body of the de-magnetizing from the molding machine, the by Rukoto over an alternating magnetic field A method for removing magnetic powder from a molded body, comprising removing magnetic powder from the surface of the molded body.   2. The method for removing magnetic particles from a compact according to claim 1, wherein the maximum magnetic field strength of the pulsed vibration attenuation magnetic field is 10 to 40 times the magnetic field strength of the alternating magnetic field. The magnetic powder filled in the cavity of the molding machine is demagnetized after being molded in a magnetic field, the molded body after this demagnetization is taken out of the molding machine and applied with a pulsed vibration damping magnetic field, and then applied with an alternating magnetic field. A magnetic particle removing device for a molded body that removes magnetic particles on the surface of a body, wherein the first powder removing coil that generates a pulsed vibration damping magnetic field, the second powder removing coil that generates an alternating magnetic field, A magnetic powder removing apparatus for a molded body, comprising a transfer device for holding and transferring the molded body taken out from the molding machine to the powder removing coil and the second powder removing coil.

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