JP3846052B2 - Magnetic polishing apparatus and magnetic polishing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a polishing device in which a magnetic polishing tool is attached to an NC machine tool or the like in place of a cutting tool, so that a plastic or glass optical lens or spectacle lens, or a metal or ceramic molding die can be used with high accuracy. In addition, the present invention relates to a magnetic polishing apparatus and a magnetic polishing method suitable for efficiently mirror-finishing.
[0002]
[Prior art]
Conventionally, as shown in FIG. 7, polishing abrasive grains 22 such as aluminum oxide having a particle diameter of several μm are attached to the surface of a ferromagnetic material particle 21 having a particle diameter of several hundreds μm in a metal-bonded state. Magnetic polishing was performed by a magnetic polishing apparatus having a general configuration shown in FIG. 6 using magnetic abrasive particles in which the material particles 21 were integrated.
[0003]
[Problems to be solved by the invention]
However, in the magnetic polishing apparatus and the magnetic polishing method shown in the above prior art, firstly, abrasive grains such as aluminum oxide having a particle diameter of several μm are adhered to the surface of the ferromagnetic material particles in a metal bonded state. In the magnetic abrasive particles, the work material that can be processed is limited to a specific material. Second, magnetic abrasive particles in which abrasive grains such as aluminum oxide having a particle size of several μm are attached to the surface of the ferromagnetic particles in a metal bonded state cannot sufficiently dissipate the processing heat due to polishing. Therefore, it greatly affects the polishing performance such as the length of the polishing time and the quality of the polished surface. Third, if the abrasive grains adhering to the surface of the ferromagnetic material particles fall off due to the friction between the workpiece and the magnetic abrasive particles, there will be no binding force due to the magnetic force, and there will be no effect on the polishing. Fourth, it is very difficult to obtain a desired shape accuracy depending on the workpiece shape. For example, when a free-form surface including a spherical surface is polished by a magnetic polishing apparatus having a conventional structure, the removal amount by polishing is small outside the processing range, and the removal amount is large at the center. Fifth, the shape of the magnetic pole and the workpiece, specifically, in the case of a workpiece made of a non-magnetic material, the magnetic flux density changes depending on the thickness of the workpiece. there were.
[0004]
Therefore, the present invention was made to eliminate such problems, and a magnetic polishing apparatus capable of obtaining high shape accuracy and appearance quality in a short time without limiting the material and shape of the workpiece, And providing a magnetic polishing method.
[0005]
[Means for Solving the Problems]
The present invention achieves the above-mentioned object, and is composed of a yoke, an exciting coil, a power source, a magnetic pole facing the workpiece, and ferromagnetic material particles. A voltage is applied to the exciting coil to generate a magnetic field between the magnetic pole facing the workpiece. However, in a magnetic polishing apparatus that relatively rotates or swings the workpiece and the magnetic pole, a slurry-like polishing liquid using Al ₂ O ₃ or CeO ₂ as an abrasive is supplied to the gap between the workpiece and the ferromagnetic particles. It is characterized by performing magnetic polishing.
[0006]
Further, instead of the ferromagnetic material particles, magnetic abrasive particles coated with brushed materials made of fibers such as cotton, silk, rayon, nylon, etc. are used.
[0007]
Further, in any one of the magnetic polishing apparatuses, when performing relative positioning of the workpiece and the magnetic pole in accordance with the workpiece shape, the normal control is performed so that the normal line at the processing point substantially coincides with the direction of the magnetic force line. Features.
[0008]
Also, any one of the above-described magnetic polishing apparatuses has a control function of maintaining a constant magnetic flux density measured in the vicinity of the processing point.
[0009]
The magnetic polishing method of the present invention is composed of a yoke, an exciting coil, a power source, a magnetic pole facing the workpiece, and ferromagnetic material particles, while applying a voltage to the exciting coil to generate a magnetic field between the magnetic pole facing the workpiece. In a magnetic polishing method in which a workpiece and a magnetic pole are relatively rotated or oscillated, a slurry-like polishing liquid using Al ₂ O ₃ or CeO ₂ as an abrasive is supplied to the gap between the workpiece and the ferromagnetic particles. However, the magnetic polishing is performed.
[0010]
Further, instead of the ferromagnetic material particles, magnetic abrasive particles coated with brushed materials made of fibers such as cotton, silk, rayon, nylon, etc. are used.
[0011]
Further, in any one of the magnetic polishing methods, when performing relative positioning of the workpiece and the magnetic pole according to the workpiece shape, the normal control is performed so that the normal line at the processing point substantially coincides with the direction of the magnetic force line. Features.
[0012]
Further, any one of the magnetic polishing methods has a control function of maintaining a constant magnetic flux density measured in the vicinity of the processing point.
[0013]
According to the above configuration of the present invention, polishing is performed by performing magnetic polishing while supplying a slurry-like polishing liquid containing Al ₂ O ₃ or CeO ₂ or the like to the gap between the workpiece and the ferromagnetic particles. The liquid not only fully absorbs the processing heat, but also supplies the polishing liquid during the polishing process, so that the abrasive material always spreads over the processing surface, and is covered with raised fibers made of fibers as magnetic abrasive particles By using the formed ferromagnetic material particles, the abrasive is held between the raised hairs as shown in FIG. 3, so that the polishing performance such as polishing time and appearance quality is not only greatly improved but also stabilized.
[0014]
Furthermore, the normal line control is performed so that the normal line at the machining point substantially coincides with the direction of the magnetic field line, and a control function for keeping the magnetic flux density measured near the machining point constant is added. Provided a magnetic polishing device and a magnetic polishing method that achieve high efficiency, high accuracy, and high appearance quality that could not be obtained by conventional technology, such as high shape accuracy that can be obtained regardless of the processing range. There is something you can do.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described with reference to the drawings. However, the present invention is not limited to the embodiments.
[0016]
Example 1
This embodiment is an embodiment in which magnetic polishing is performed while supplying a slurry-like polishing liquid to the gap between the workpiece and the ferromagnetic material particles, and will be described with reference to FIG.
[0017]
First, ferromagnetic material particles 8 made of ferrite and having a particle diameter of 10 μm to 500 μm are filled in a gap 3 mm between the magnetic pole 24 and the work 1, and a magnetic field is applied to the yoke 3. In addition, the particle size of the ferromagnetic material particles 8 made of ferrite is selected appropriately depending on the material of the workpiece and the degree of the finished surface roughness of the pre-processing of polishing. Subsequently, relative movement between the magnetic pole 24 and the work 1 is performed by the linear positioning means 6 and the work rotating means 10, and the spindle 2 is rotated. At the same time, an abrasive suitable for polishing the workpiece 1 prepared in advance and a slurry-like polishing liquid 9 in which water, a surfactant, an antifoaming agent, etc. are mixed are ferromagnetically bonded to the workpiece 1 by a supply pump (not shown). It is constantly or intermittently supplied between the material particles 8.
[0018]
In addition, when the material of the workpiece is plastic, Al ₂ O ₃ is cited as the most suitable abrasive material, and when the workpiece is glass, CeO ₂ is cited as the most suitable abrasive material. Abrasive material suitable for the workpiece material should be selected.
[0019]
By doing so, not only can the abrasive material in the polishing liquid be always supplied between the surface of the workpiece 1 and the ferromagnetic material particles 8 during processing, but the polishing liquid also absorbs frictional heat from the processing. Therefore, it was possible to easily achieve the desired surface roughness or appearance accuracy in a short time.
[0020]
(Example 2)
In this example, ferromagnetic abrasive particles coated with raised fibers made of fibers are used as magnetic abrasive particles, and magnetic polishing is performed while supplying a slurry-like polishing liquid to the gap between the workpiece and the ferromagnetic particles. This will be described with reference to FIG.
[0021]
First, magnetic abrasive particles 11 were prepared by the following procedure. The surface of the ferromagnetic material particles 12 made of ferrite and having a particle size of 10 μm to 500 μm is covered with an adhesive layer 25, and fiber raised parts 13 are attached to the surface of the adhesive layer 25 to obtain the magnetic abrasive particles 11. The magnetic abrasive particles 11 thus obtained are filled in a gap of 3 mm between the magnetic pole 24 and the work 1, and a magnetic field is applied to the yoke 3. In addition, what is necessary is just to select an appropriate value for the particle size of the ferromagnetic material particles 12 made of ferrite depending on the material of the workpiece and the degree of the finished surface roughness of the pre-processing of polishing. Subsequently, relative movement between the magnetic pole 24 and the work 1 is performed by the linear positioning means 6 and the work rotating means 10, and the spindle 2 is rotated. At the same time, a slurry-like polishing liquid 9 in which an abrasive suitable for polishing the work 1 prepared in advance and water, a surfactant, an antifoaming agent, etc. are mixed is processed with the work 1 by a supply pump (not shown). It is constantly or intermittently supplied between the magnetic abrasive particles 11. By doing so, not only can the abrasive in the polishing liquid be always supplied between the surface of the workpiece 1 and the magnetic abrasive particles 11 during processing, but also strong as shown in FIG. Compared to the case of the magnetic material particles alone, a large amount of abrasive grains 14 are held between the raised hairs. Therefore, the opportunity for the abrasive grains 14 to come into contact with the surface of the work 1 is increased, whereby the polishing efficiency is further improved, and the desired surface roughness or appearance quality can be obtained in a short time.
[0022]
Example 3
The present embodiment is an embodiment in which magnetic polishing is performed while controlling the normal of the workpiece so that the normal at the machining point substantially coincides with the direction of the magnetic force line, and will be described with reference to FIG.
[0023]
As the ferromagnetic material particles and the polishing liquid, those described in the first and second embodiments, or those suitable for the work material and the surface roughness of the pre-processing are used, and the apparatus configuration shown in FIG. 1 or FIG. In addition, as shown in FIG. 4, the work 1 is swung around the swivel center 19 so that the contact point at the time of polishing, that is, the normal line 17 set at an arbitrary processing point Pn substantially coincides with the direction 15 of the magnetic force line. A workpiece turning means for controlling the workpiece normal is added. By controlling the normal of the workpiece with the above apparatus configuration, for example, even in a workpiece having a free-form surface including a spherical surface, the machining point, precisely the machining range, is always the center of the magnetic pole 24. However, the removal amount by polishing becomes almost constant. Therefore, it is possible to easily obtain a desired shape accuracy even for a work made of a nonmagnetic material and having a complicated free-form surface shape.
[0024]
Example 4
The present embodiment is an embodiment of magnetic polishing using a magnetic polishing apparatus having a control function that keeps the magnetic flux density measured near the processing point constant, and will be described with reference to FIG.
[0025]
In addition to the apparatus configuration and control method of the third embodiment, the magnetic flux density measuring sensor 20 shown in FIG. 5 monitors the magnitude of the magnetic flux density during machining near the machining point so that the magnetic flux density is always constant. In addition, although not shown, a closed loop current control circuit in which feedback is applied to the magnetic flux density is configured. By adopting such a configuration, the magnetic flux density is controlled to be constant even in the case of a workpiece having a free-form surface shape including, for example, a spherical surface. The force, that is, the polishing pressure can be kept constant. Therefore, it has become possible to easily obtain a desired shape accuracy even for a non-magnetic material workpiece having a complicated free-form surface shape, which has heretofore been extremely difficult to obtain a desired shape accuracy.
[0026]
【The invention's effect】
As described above, according to the present invention, the slurry-like polishing liquid is supplied to the gap between the workpiece and the ferromagnetic material particles during processing, and the magnetic abrasive particles are coated with the nappings made of fibers. By using magnetic material particles, it is possible to greatly improve the polishing performance such as shortening the polishing time, improving the surface roughness, and improving the appearance quality, regardless of the material of the workpiece. Furthermore, the normal line control is performed so that the normal line at the machining point substantially coincides with the direction of the magnetic field line, and a control function for keeping the magnetic flux density measured near the machining point constant is added. High shape accuracy can be obtained regardless of the processing range. Therefore, it is possible to provide a magnetic polishing apparatus and a magnetic polishing method that realize high efficiency, high accuracy, improvement in surface roughness and high appearance quality, which could not be obtained with the prior art.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a magnetic polishing apparatus used in Example 1. FIG. 2 is a diagram showing a configuration of a magnetic polishing apparatus used in Example 2. FIG. 3 is a magnetic material abrasive particle used in Example 2. FIG. 4 is a diagram showing a configuration of a magnetic polishing apparatus used in Example 3. FIG. 5 is a diagram showing a configuration of a magnetic polishing apparatus used in Example 4. FIG. 6 is a diagram of a conventional magnetic polishing apparatus. FIG. 7 is a sectional view of magnetic abrasive particles used in a conventional magnetic polishing method.
DESCRIPTION OF SYMBOLS 1 Work 2 Spindle 3 Yoke 4 Excitation coil 5 Power supply 6 Linear positioning means 7 Linear positioning means drive motor 8 Ferromagnetic material particles 9 Slurry polishing liquid 10 Work rotating means 11 Magnetic abrasive particles 12 Ferromagnetic material particles 13 Brushed 14 Abrasive grain 15 Direction of magnetic force line 16 Ferromagnetic material particle 17 Normal line 18 set at an arbitrary processing point Pn in a state where normal control is performed A normal line 19 set at an arbitrary processing point Pn in a horizontal state 19 Rotating center 20 Magnetic flux density measurement sensor 21 Ferromagnetic material particle 22 Abrasive grain 23 Conventional magnetic abrasive particle 24 Magnetic pole 25 Adhesive layer

Claims (4)

It consists of a yoke, an excitation coil, a power supply, a magnetic pole facing the workpiece, and ferromagnetic particles. A voltage is applied to the excitation coil and a magnetic field is generated between the magnetic pole facing the workpiece and the workpiece and the magnetic pole rotate relatively. Alternatively, in a magnetic polishing apparatus to be oscillated, a ferromagnetic polishing material in which a slurry-like polishing liquid using Al ₂ O ₃ or CeO ₂ or the like as an abrasive is covered with a brushed material made of a material such as cotton, silk, rayon, or nylon. A magnetic polishing apparatus that performs magnetic polishing while supplying it to a gap with a material particle. 2. The magnetic polishing apparatus according to claim 1, wherein when the relative positioning of the workpiece and the magnetic pole is performed in accordance with the workpiece shape, the normal control is performed so that the normal line at the processing point substantially coincides with the direction of the magnetic force line. Magnetic polishing device. It consists of a yoke, an excitation coil, a power supply, a magnetic pole facing the workpiece, and ferromagnetic particles. A voltage is applied to the excitation coil and a magnetic field is generated between the magnetic pole facing the workpiece and the workpiece and the magnetic pole rotate relatively. Alternatively, in a magnetic polishing method that swings, a ferromagnetism in which a slurry-like polishing liquid using Al ₂ O ₃ , CeO ₂ or the like as an abrasive is coated with a brushed material made of a material such as cotton, silk, rayon, or nylon. A magnetic polishing method, wherein magnetic polishing is performed while supplying the gap to the material particles. 4. The magnetic polishing method according to claim 3, wherein when the relative positioning of the workpiece and the magnetic pole is performed in accordance with the workpiece shape, the normal control is performed so that the normal line at the processing point substantially coincides with the direction of the magnetic force line. Magnetic polishing method.

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