JP7026927B2 - Magnetic polishing method and magnetic polishing equipment - Google Patents

Description

The present invention relates to a magnetic polishing method and a magnetic polishing apparatus, and more particularly to a method and an apparatus capable of mirror polishing even a hard object to be polished with a magnetic abrasive.

The magnetic assist processing method (also called magnetic polishing method) is a precision processing technology that incorporates the action of a magnetic field, and realizes precise surface processing by applying processing force and kinetic force to a magnetic polishing agent via magnetic lines of force. It is a thing. For example, in Patent Document 1, a magnetic abrasive is particularly used as a particle brush, and precision polishing is performed while maintaining the shape accuracy of a complicated part such as a curved surface of a mold due to the flexible processing behavior of the particle brush. It is proposed that it can be done.

Patent Document 2 proposes a magnetic polishing device capable of efficiently polishing even a workpiece made of a magnetic metal material. This device is equipped with a magnetic polishing tool having a tip structure in which two or more permanent magnets that magnetically attract the magnetic polishing agent are fixed to each other at a distance from the yoke, and the magnetic polishing agent is attached to the tip of the magnetic polishing tool. Is magnetically attracted and then moved relative to the workpiece while rotating or rotating to polish the workpiece.

Further, Patent Document 3 proposes an ultra-precision magnetic polishing method capable of extremely precisely polishing the inner surface of a tube and easy to clean. This technique uses a tube inner surface magnetic polishing device that agitates the polishing slurry by relatively moving the tube to be polished, the polishing slurry introduced into the tube to be polished, and the tube to be polished and the polishing slurry, and magnetically polishing the inner surface of the tube. This is a method of operating an apparatus to polish the inner surface of a tube to be polished with a polishing slurry.

JP-A-2002-192453 Japanese Unexamined Patent Publication No. 2007-210073 Japanese Unexamined Patent Publication No. 2010-52123

In the method or apparatus proposed in each of the above-mentioned patent documents, the surface to be processed is polished with a magnetic abrasive magnetically adsorbed on the surface of the magnet. Therefore, there is a problem in processing efficiency that the processing force is weak and the polishing time is long. In particular, when polishing an object to be polished made of a hard material, it is difficult to perform a highly efficient and highly accurate polishing process.

The present invention has been made to solve the above problems, and an object thereof is magnetism capable of realizing highly efficient and highly accurate polishing even when polishing an object to be polished made of a hard material. It is an object of the present invention to provide a polishing method and a magnetic polishing apparatus.

(1) The magnetic polishing method according to the present invention is a method of polishing the surface of an object to be polished with a magnetic polishing agent magnetically attracted to a magnet, and the magnet is arranged at a position sandwiching the object to be polished. These are an N-pole magnet and an S-pole magnet, and are characterized in that each magnet and the object to be polished are relatively moved while pressurizing each magnet toward the object to be polished.

According to the present invention, the N-pole magnet and the S-pole magnet arranged at positions sandwiching the object to be polished are pressed against the object to be polished, and each magnet (N-pole magnet and S-pole magnet) and the object to be polished are pressed. Since it moves relative to the body, the surface of the object to be polished can be polished with high efficiency and high accuracy.

In the magnetic polishing method according to the present invention, the relative movement is the rotation of the object to be polished or the rotation of each magnet, and / or the vibration or oscillation of the object to be polished or the vibration or oscillation of each magnet. Is preferable. According to the present invention, the surface of various objects to be polished can be polished by adjusting the element that relatively moves each magnet and the object to be polished according to the hardness and shape of the object to be polished.

In the magnetic polishing method according to the present invention, it is preferable that the magnetic polishing agent is a mixed particle having a different particle size. According to the present invention, it is possible to improve the efficiency and polishing accuracy of polishing by using the mixed particles.

In the magnetic polishing method according to the present invention, the object to be polished is a rod-shaped workpiece. In particular, it can be preferably applied to an object to be polished made of a hard material such as alumina ceramics.

(2) The magnetic polishing device according to the present invention is a device that polishes the surface of the object to be polished with a magnetic polishing agent magnetically attracted to a magnet, and includes an object mounting portion on which the object to be polished is attached and the object to be polished. An N-pole magnet and an S-pole magnet mounted on the object to be polished and arranged at positions sandwiching the object to be polished, a pressurizing device for pressurizing each magnet toward the object to be polished, and each of the above. It is characterized by including at least a relative moving mechanism for relatively moving the magnet and the object to be polished.

According to the present invention, a pressurizing device for pressurizing an N-pole magnet and an S-pole magnet arranged at positions sandwiching the object to be polished toward the object to be polished is provided, and the pressurizing device is used to pressurize the magnet. Since it is provided with a relative movement mechanism that relatively moves each magnet and the object to be polished, the surface of the object to be polished can be polished with high efficiency and high accuracy.

In the magnetic polishing device according to the present invention, the relative moving mechanism is a rotating device that rotates the object to be polished or each magnet, and / or a vibration / shaking device that vibrates or swings the object to be polished, or the above. A vibration / swing device that vibrates or swings each magnet is preferable.

According to the present invention, it is possible to provide a magnetic polishing method and a magnetic polishing apparatus capable of realizing highly efficient and highly accurate polishing even when polishing an object to be polished made of a hard material. Specifically, since the N-pole magnet and the S-pole magnet arranged at positions sandwiching the object to be polished are relatively moved between the magnet and the object to be polished while pressurizing the magnet to be polished. The surface of the body can be polished with high efficiency and high accuracy.

It is a schematic diagram which shows an example of the magnetic polishing method which concerns on this invention. It is a schematic diagram which shows another example of the magnetic polishing method which concerns on this invention. This is an example of the magnetic polishing device used. It is a graph which shows the relationship between the air pressure (0 to 0.35 MPa) given to a magnet, and the polishing pressure of a magnet. It is the surface roughness result before polishing (A), after polishing for 5 minutes (B), and after polishing for 10 minutes (C) when the air supply pressure is 0.25 MPa. The upper row is the contact type surface roughness measurement result, and the lower row is the non-contact type surface roughness measurement result. It is a graph summarizing the influence of the polishing time on the surface roughness and the polishing amount when the air supply pressure is changed in 3 steps (0.05MPa, 0.15MPa, 0.25MPa). It is a graph summarizing the influence of the polishing time on the surface roughness and the polishing amount when the distance between the object to be polished and each magnet is changed. It is a graph summarizing the influence of the polishing time on the surface roughness and the polishing amount when the amount of magnetic particles is changed. It is a graph summarizing the influence of the polishing time on the surface roughness and the polishing amount when the polishing time is changed. (A) is the result of surface roughness, and (B) is the result of the amount of polishing. It is a graph which summarized the surface pressure of the object to be polished by the difference in the tip shape of a magnet.

Hereinafter, the magnetic polishing method and the magnetic polishing apparatus of the present invention will be described with reference to the drawings. It should be noted that the present invention includes the scope having the technical features thereof, and is not limited to the explanations and drawings shown below.

[Magnetic polishing method and equipment]
As shown in FIGS. 1 to 3, the magnetic polishing method according to the present invention is a method of polishing the surface of an object to be polished 1 with a magnetic polishing agent 2 magnetically attracted to a magnet 21. The magnet 21 is an N-pole magnet 21N and an S-pole magnet 21S arranged at positions sandwiching the object to be polished 1. While pressing each magnet 21 (N-pole magnet 21N and S-pole magnet 21S) toward the object to be polished 1, each magnet 21 and the object to be polished 1 are relatively moved.

As shown in FIGS. 1 to 3, the magnetic polishing device 31 according to the present invention is also a device that polishes the surface of the object to be polished 1 with the magnetic polishing agent 2 magnetically attracted to the magnet 21, and is equipped with the object to be polished 1. The N-pole magnet 21N and the S-pole magnet 21S arranged at positions sandwiching the object to be polished 31 and the body 1 to be polished mounted on the body 1 to be polished, and each magnet 21 is attached to the body 1 to be polished. It is provided with at least a pressurizing device 32 for pressurizing toward the surface and a relative moving mechanism 33 for relatively moving each magnet 21 and the object to be polished 1.

In such a magnetic polishing method and apparatus, each magnet 21 and the object to be polished 1 are pressed toward the object 1 to be polished by pressing the N-pole magnet 21N and the S-pole magnet 21S arranged at positions sandwiching the object 1 to be polished. Since and are relatively moved, the surface of the object to be polished 1 can be polished with high efficiency and high accuracy. In particular, in the present invention, in magnetic polishing in a state where the magnetic polishing agent 2 is interposed between the object to be polished 1 and each magnet 21, the N-pole magnet 21N and the S-pole magnet 21S arranged so as to sandwich the object to be polished 1 The point that they are magnetically attracted to each other (first feature), the point that pressure is applied to the north pole magnet 21N and the south pole magnet 21S toward the object to be polished 1 (second feature). Further, it is characterized in that each magnet 21 and the object to be polished 1 are polished in a state of relative movement (third feature).

Hereinafter, each component will be described in detail. The term "magnet 21" or "each magnet 21" simply refers to both the N-pole magnet 21N and the S-pole magnet 21S.

(Object to be polished)
The object to be polished 1 is to be polished, and its shape and material are not particularly limited. The shape may be a rod shape such as a round bar or a square bar, a spherical shape, a plate shape, or a rectangular shape, and may be a structural form capable of realizing the above-mentioned first to third features. .. Further, the form of the object to be polished 1 may be a uniform constant form, a bent form, a form having a step, or a form in which the size changes in the middle. In short, any form can be used as long as it can realize the first to third features, and the N-pole magnet 21N arranged across the object to be polished 1 such as a sphere that is too large, a plate that is too thick, or a rectangular object that is too large. When the S pole magnet 21S and the S pole magnet 21S cannot be magnetically attracted to each other, the effect of the present invention may not be fully exerted. Preferred examples are a round bar having a diameter of 20 mm or less or a square bar having a thickness of 20 mm or less in the case of a bar, a square bar having a diameter of 20 mm or less in the case of a sphere, and a thickness of 10 mm or less in the case of a plate or a rectangular object. Is preferable. In the experimental example described later, a round bar having a uniform diameter is used.

The material may be a non-magnetic material or a magnetic material. Examples of the material of the non-magnetic material include plastics, glass, ceramics, non-magnetic metals (copper, aluminum, non-magnetic steel, non-magnetic stainless steel, titanium, etc.). Examples of the material of the magnetic material include steel, magnetic stainless steel, nickel, and magnetic alloys. However, when the object 1 to be polished is a magnetic material, the magnetic polishing agent 2 magnetically attracts to each magnet 21 having a magnetic force larger than that of the magnetic material, and functions as a polishing agent. In the experimental example described later, the material of the object to be polished 1 is alumina ceramics, and particularly hard ceramics such as alumina (aluminum oxide) and zirconia (zirconium oxide) can be preferably polished.

(Mounting part to be polished)
The body to be polished 31 is a constituent member included in the magnetic polishing device 30, and is not particularly limited as long as it is a member to which the body 1 to be polished is mounted, as shown in FIGS. 1 to 3. In the example of FIG. 3, since the round bar is used as the object to be polished 1, the round bar is fixed by the circular tubular mounting auxiliary member 31a, and the mounting assist member 31a is fixed by the polished body mounting portion 31. The body mounting portion 31 to be polished is rotated by the rotating device 34. The body to be polished 31 and the mounting auxiliary member 31a are not limited to the examples of FIGS. 1 to 3.

(Magnetic abrasive)
The magnetic abrasive 2 is magnetically attracted to each magnet 21 and acts to polish the object to be polished 1. The magnetic polishing agent 2 is a polishing slurry containing magnetic particles and polishing particles. The magnetic polishing agent 2 is magnetically attracted to each magnet 21 even if each magnet 21 and the object to be polished 1 move relative to each other, and the surface of the object to be polished 1 is polished based on the relative movement. By the relative movement of the magnetic abrasive 2, the surface of the object to be polished 1 can be polished with high efficiency and high accuracy.

The magnetic particles constituting the magnetic abrasive 2 are not particularly limited and may have any shape. For example, the particles may be spherical or substantially spherical, or may be non-spherical square or amorphous particles. The magnetic particles act so that the magnetic abrasive 2 is magnetically attracted to the magnet 21 and held between the object 1 to be polished and the magnet 21. By the relative movement of the object to be polished 1 and the magnet 21 in a manner of being magnetically attracted to the magnet 21, the effect of accurately polishing the surface of the object to be polished 1 with the magnetic abrasive 2 can be obtained. Therefore, the magnetic particles need to have magnetic properties and particle sizes that exert such effects.

As the magnetic particles, particles containing all or a part of an element generally called a magnetic substance such as iron, cobalt, nickel, chromium and their oxides, alloys and compounds are used. As a specific example, nickel alloy powder such as carbonyl iron powder, electrolytic iron powder, nickel powder, Ni-P alloy powder or Ni-B alloy powder can be used. It is also possible to use aluminum oxide powder sintered with iron in an inert gas under high temperature and high pressure, or a product powder of a thermite reaction between aluminum in an inert gas atmosphere and iron oxide. A commercially available magnetic abrasive (Toyo Abrasive Industry Co., Ltd .; KMX-80), another uncommercially available magnetic abrasive, or the like can be used. Further, the particles may be particles obtained by coating the surface of a magnetic powder with another material.

The size of the magnetic particles is not particularly limited, but it is preferable that the magnetic particles are larger than the abrasive particles in terms of the relative relationship with the abrasive particles. As an example, it can be arbitrarily selected in the range of 4 times or more and 1000 times or less, preferably 4 times or more and 50 times or less of the abrasive particles. That is, the magnetic polishing agent 2 containing the magnetic particles and the polishing particles is preferably mixed particles having different particle sizes, and the mixed particles can be used to improve the efficiency and polishing accuracy of polishing. The relationship between the size of the magnetic particles and the size of the polished particles is the surface condition of the object to be polished 1 before polishing (including the degree of surface roughness), the required surface condition of the surface of the object to be polished, and the required surface condition. It is arbitrarily selected depending on the polishing time and the like.

The particle size of the magnetic particles is not particularly limited, and any particle size may be used as long as the average particle size has a certain range. For example, the average particle size may be 0.5 μm or more and 500 μm or less. The average particle size is arbitrarily selected according to the polishing stage and type of the object to be polished 1. For example, when large polishing particles are used during rough polishing of the object to be polished 1 or when polishing a hard object to be polished 1, magnetic particles having a large particle size are selected within a relative dimensional range with the polishing particles. When small polishing particles are used during finish polishing of the object to be polished 1 or when polishing the object to be polished 1 which is not very hard, magnetic particles having a small particle size within the relative dimensional range with the polishing particles are generated. It is preferred to be selected. That is, it is arbitrarily selected depending on the polishing stage (rough polishing, normal polishing, finish polishing, etc.), the hardness of the object to be polished 1, and the like. Such selection has the effect of being able to perform even more precise polishing of high-hardness ceramics, which has traditionally been difficult to perform with high-precision polishing. The average particle size is an average value measured from an electron micrograph of magnetic particles, and the surface roughness (Ra) is an arithmetic mean roughness measured based on JIS B 0601 (2001).

As described above, the polished particles preferably have a relative dimensional relationship with the magnetic particles. The form of the polished particles is not particularly limited, and various forms can be used. Examples of the abrasive particles include diamond particles, aluminum oxide particles, cerium oxide particles, silicon carbide particles, silicon dioxide particles, chromium oxide particles, or a composite thereof. Also, Al ₂ O ₃ , SiC, ZrO ₂ , B ₄ C, diamond, cubic boron nitride, including those represented as A, WA, GC, SA, MA, C, MD, CBN in JIS notation, Abrasive particles such as MgO, CeO ₂ or fumed silica may be used.

The particle size of the polished particles is preferably the size described above for the magnetic particles. Since the polishing particles polish the object to be polished 1 so as to be sandwiched between the magnetic particles and the object to be polished 1, the surface of the object to be polished 1 is precisely polished with fine abrasive particles uniformly dispersed without agglomeration. be able to. The average particle size is an average value measured from an electron micrograph of the polished particles, and the surface roughness (Ra) is an arithmetic average roughness measured based on JIS B 0601 (2001).

The slurry medium is contained in the magnetic polishing agent 2, and is a medium for forming the magnetic particles and the polishing particles into a slurry, and is a medium for dispersing the polishing particles in the magnetic polishing agent 2. Preferred media for forming a slurry include light oil, water, and water-soluble and oil-soluble liquids generally used as polishing liquids.

In the magnetic polishing agent 2 configured in this way, the content of the magnetic particles contained in the magnetic polishing agent 2 is usually in the range of 30% by mass to 70% by mass, and the content of the polishing particles is 10% by mass to 60% by mass. It is in the range of mass%, and the total content of these magnetic particles and the abrasive particles is configured to be in the range of 70% by mass to 90% by mass. The content of the magnetic particles is also related to the conditions such as the magnetic polishing device and the particle size of the magnetic particles, and the content of the polishing particles is the degree of polishing of the surface of the object to be polished 1 (coarse polishing, normal polishing). , Finish polishing, etc.) and polishing efficiency are taken into consideration. Further, the content of the slurry medium is such that the prepared magnetic polishing agent 2 is magnetically attracted to the magnet 21 by the relative motion between the object to be polished 1 and the magnet 21 and remains as a fluid. Set to have viscosity. Further, by preparing a plurality of types of magnetic abrasives 2 suitable for each stage of polishing accuracy such as rough polishing, normal polishing, finish polishing, etc., polishing can be performed for each stage. For example, depending on whether rough polishing, intermediate polishing, or finish polishing is performed, a plurality of magnetic abrasives 2 having an average particle size suitable for the magnetic particles and the polishing particles are prepared and used step by step to improve the polishing efficiency. You may let me.

(magnet)
As shown in FIGS. 1 to 3, the magnet 21 is arranged at a position sandwiching the object to be polished 1 to be attached to the body to be polished 31. In the illustrated example, the N-pole magnet 21N and the S-pole magnet 21S are arranged at opposite positions sandwiching the object to be polished 1. The strength (magnetic force) of the magnet 21 is determined in consideration of other conditions (material and size of the object to be polished 1, type of magnetic polishing agent 2, etc.), so it cannot be said unconditionally, but the magnetic polishing agent. A magnetic force sufficient to magnetically attract 2 is required, but the type of magnet 21 is not particularly limited and may be a permanent magnet or an electromagnet. Examples of permanent magnets include rare earth magnets, ferrite magnets, alnico magnets, MA magnets, and the like. Rare earth magnets are preferable because they can obtain a strong magnetic field. As the rare earth magnet, specifically, a neodymium magnet (Nd-Fe-B) or a samarium-cobalt magnet (Sm-Co) is preferably used.

Since the N-pole magnet 21N and the S-pole magnet 21S face each other with the object to be polished 1 interposed therebetween, the N-pole magnet 21N and the S-pole magnet 21S can attract each other. The facing positions are preferably 180 °, but the positions are not necessarily limited to 180 ° as long as they are mutually attractive, and may be in the range of, for example, 150 ° to 210 °. The number of magnets 21 may be one set (two in total) arranged at opposite positions, but two sets may be arranged.

The shapes of the N-pole magnet 21N and the S-pole magnet 21S are also not particularly limited, and usually, a columnar magnet such as a cylinder or a polygonal column is used. Further, from the viewpoint of increasing the magnetic flux density, the tips of the N-pole magnet 21N and the S-pole magnet 21S may have a weight trapezoidal shape, for example, a conical trapezoidal shape or a square trapezoidal shape. Further, since the magnetic field strength at the corners of the magnet 21 is increased, the tips of the N-pole magnet 21N and the S-pole magnet 21S can be shaped so as to have a notch. Further, the shape of the magnet 21 may be changed according to the shape of the object to be polished 1. For example, as shown in FIG. 2, for the object 1 to be polished having a curved surface, a step, an unevenness, etc., the tip of the magnet may be changed. A part may be processed according to the shape. For example, in the case of a curved surface, the tip of the magnet may be processed to match the curved surface, in the case of a step, the tip of the magnetic force may be processed to match the step, and in the case of unevenness, the tip of the magnet may be processed to match the step. The tip of the magnetic force may be processed so as not to exceed the size of the unevenness.

(Polishing)
In the present invention, as shown in FIGS. 1 to 3, each magnet 21 and the object to be polished 1 are moved relative to each other while applying pressure F (pressurizing) toward the object to be polished 1 for polishing. do. The magnetic polishing device 30 for polishing by this method includes a pressurizing device 32 that applies pressure F toward the object to be polished 1 with each magnet 21, and a relative moving mechanism 33 for relatively moving each magnet 21 and the object to be polished 1. And at least have. By such a method and an apparatus, the surface of the object to be polished 1 can be polished with high efficiency and high accuracy.

The pressurizing means may be any of pneumatic pressure, hydraulic pressure, mechanical pressure and the like, and is not particularly limited. The pressure F to be applied is arbitrarily set according to the type of the object to be polished 1, the relationship with the polishing force of the magnetic abrasive 2, and the desired state of the polished surface. For example, in the experimental example described later, the pressure is increased by air pressure, and the pressure F is in the range of 0.05 to 0.35 N / mm ² . The applied air pressure and the pressure F applied to the object to be polished 1 have a substantially proportional relationship.

Relative movement may be performed as long as the object to be polished 1 and each magnet 21 are relatively moving, one may be fixed and the other may be moved for polishing, or both may be moved for polishing. good. The form of relative movement is preferably rotation of the object to be polished 1 or rotation of each magnet 21 and / or vibration or rocking of the body to be polished 1 or vibration or rocking of each magnet 21. By adjusting the elements of such relative movement, the surface of the object to be polished 1 having various hardness can be effectively polished. The rotation is performed by the rotating device 34, and the vibration or swing of each magnet 21 is performed by the vibration / swing device. The rotating device 34 is not particularly limited, but as shown in FIGS. 1 to 3, it is preferable that the rotating device 34 is a device that rotates the object to be polished body 31 to which the object to be polished 1 is attached, but is a device that rotates each magnet 21. May be. Further, the vibration / swing may be performed in combination with the rotation, or may be performed by either one.

In the relative movement mechanism 33 in the experimental example of FIG. 3, the object to be polished 31 to which the rod-shaped workpiece (object to be polished 1) is attached is rotated, each magnet 21 is fixed, and the object 1 to be polished and each magnet 21 are used. Is relatively moved and polished. Further, a swing mechanism 33a using a cam is provided so that each magnet 21 swings in the axial direction of the rod-shaped workpiece. Further, a moving mechanism 33b that can move the polishing position of the rod-shaped workpiece is provided. In the magnetic polishing device 30 provided with such a relative movement mechanism 33, the magnet 21 is pressurized toward the object to be polished 1 by the pneumatic pressurizing device 32.

As described above, according to the present invention, it is possible to finish the surface of the object to be polished 1 such as a rod-shaped workpiece with high efficiency and high accuracy. The N-pole magnet 21N and the S-pole magnet 21S are arranged at positions facing each other so as to sandwich the object to be polished 1, the magnetic polishing agent 2 is magnetically attracted to the surface of each magnet 21, and the N-pole magnet 21N and the S pole are further arranged. The magnet 21S is processed with the pressure F applied toward the object to be polished 1. In this way, the surface of the object to be polished 1 can be polished with high efficiency and high accuracy. In particular, even an object to be polished 1 made of a hard ceramic material such as alumina or zirconia can realize ultra-precision machining. This technology can be expected to be applied in a wide range of technical fields such as space-related industrial fields, medical fields, semiconductor industry fields, and automobile industry fields.

The present invention will be described in more detail with reference to experimental examples. The scope of the present invention is not limited to the following experimental examples.

[Experiment 1]
The magnetic polishing apparatus 30 shown in FIGS. 1 and 3 was used. The magnetic polishing device 30 is a device provided with a swinging mechanism 33a that rotates the object to be polished 1 and swings the magnet 31 and a moving mechanism 33b that moves the polishing position. The object to be polished 1 is an alumina ceramic rod having a diameter of 10 mm and a length of 50 mm. They were arranged so as to sandwich the rods so as to face each other by 180 °. The magnetic abrasive 2 was magnetically adsorbed on the tips of the N-pole magnet 21N and the S-pole magnet 21S. An alumina ceramic rod is fixed to a tubular member (mounting auxiliary member 31a), the tubular member is fixed to a lathe chuck (mounting portion 31 to be polished), rotated at a rotation speed of 1600 per minute, and further, an N-pole magnet 21N. By swinging the S pole magnet 21S with a cam (swing mechanism 33a), the surface of the object to be polished 1 was polished by the relative motion between the surface of the alumina ceramic rod and the magnetic abrasive 2. The experimental conditions are as follows.

(Polishing conditions)
Body to be polished: Alumina ceramic rod (diameter 10 mm, length 50 mm)
Magnet: Fe-Nd-B system rare earth magnet Magnet vibration: Amplitude 10mm, frequency 1.3Hz
Magnet rotation speed: 1600 rpm
Polishing time: 5 minutes, 10 minutes Magnetic polishing agent: Magnetic particles (electrolytic iron powder with an average particle size of 330 μm, Toho Zinc Co., Ltd.), polishing particles (diamond particles with a particle size range of 0 to 1.5 μm, manufactured by Microdiamant) , Slurry medium (manufactured by Castrol, trade name: Honairo 998, chlorine-free)
Composition of magnetic abrasive: electrolytic iron powder 8 g, diamond particles 0.2 g, slurry medium 3 mL
Air supply pressure: 0 to 0.35 MPa (this is the value measured by the pressure control machine)

[Measurement and results]
(Pressure applied to the surface of the object to be polished)
FIG. 4 is a graph showing the relationship between the air pressure (0 to 0.35 MPa) applied to the magnet 21 and the polishing pressure of the magnet 21. As shown in FIG. 1, "a" in FIG. 4 is applied to the surface of the object to be polished when it is pneumatically pressed with the magnetic abrasive 2 between the object 1 to be polished and the magnet 21. It's pressure. “B” in FIG. 4 is the pressure applied to the surface of the object to be polished when the object to be polished 1 and the magnet 21 are pressurized by air pressure without the magnetic abrasive 2 interposed therebetween. “C” in FIG. 4 is the pressure (kPa) applied to the surface of the object to be polished when the surface of the object to be polished 1 is simply pressurized with air pressure. The pressure applied to the surface of the object to be polished has an area of 0.000216 mm ² on the magnet surface facing the object 1 to be polished, and a tensile test gauge (manufactured by Oba Keiki Seisakusho Co., Ltd.) is used based on the surface area. It is a measured and calculated value.

As shown in the result of FIG. 4, the pressure F on the surface of the object to be polished 1 is increased by about 100 kPa due to the arrangement of the magnets 21 facing each other (b) as compared with the case of only the air pressure (c). .. This is because the magnets facing each other are attracted to each other. Further, the magnetic abrasive 2 is interposed between the object 1 to be polished and each magnet 21 (a), so that the pressure F on the surface of the object 1 to be polished is further increased by about 30 kPa. This is probably because the magnetic particles contained in the magnetic polishing agent 2 are magnetized by the magnet 21, and the magnetic particles magnetized by each magnet 21 are attracted to each other. From these results, it was found that according to the present invention, the pressure F on the surface of the object to be polished 1 can be effectively increased by the air pressure, the magnet and the magnetic abrasive.

(Surface Roughness) FIG. 5 shows the surface roughness results before polishing (A), after 5-minute polishing (B), and after 10-minute polishing (C) when the air supply pressure is 0.25 MPa. The upper row is the contact type surface roughness measurement result, and the lower row is the non-contact type surface roughness measurement result. As for the surface roughness, the rotation was stopped after a predetermined time had passed, the object to be polished was ultrasonically cleaned with ethanol for 5 minutes, and the surface roughness Ra was measured. At the same time, the weight of the object to be polished 1 before and after polishing was weighed and the amount of polishing was measured. The contact-type surface roughness measurement was performed by a stylus-type roughness measuring machine (Mitutoyo Co., Ltd., model number: SV-624-3D) and measured by a method based on JIS B 0601 (2001). The value of the average roughness was expressed as the surface roughness Ra. For the non-contact type surface roughness measurement, a non-contact surface roughness measuring device (manufactured by ZYGO, model number: Zygo, NewView7300) was used to obtain a surface roughness and a three-dimensional shape image. In each method, the surface of the object to be polished was measured at three points in the circumferential direction at 120 ° intervals, and the average value was adopted.

As described in FIG. 5, although the surface roughness Ra value is slightly different between the contact type and the non-contact type, the surface roughness of the object to be polished before polishing is compared with that after polishing for 5 minutes or for 10 minutes. The surface roughness after polishing was extremely small, and extremely smooth mirror polishing could be realized by polishing. Further, as can be seen from the lower three-dimensional shape image, it was found that the surface after magnetic polishing became a smooth nano-level smooth surface. The same test was performed even when the air supply pressure was 0.05 MPa and 0.15 MPa, but the tendency was the same as that of 0.25 MPa in FIG.

FIG. 6 is a graph summarizing the effects of polishing time on the surface roughness and the amount of polishing when the air supply pressure is changed in three steps (0.05 MPa, 0.15 MPa, 0.25 MPa). The polishing time was 0, 5 minutes, and 10 minutes. After polishing for 5 minutes, the surface roughness was remarkably reduced at any air supply pressure. This effect of improving the surface roughness was remarkable as compared with the polishing amount which is proportional to the polishing time. Further, in the range of the experiment here, the air supply pressure showed the same improvement effect of the surface roughness as 0.15 MPa and 0.25 MPa.

[Experiment 2]
The influence of the polishing time on the surface roughness and the polishing amount was examined when the distance between the object to be polished 1 and each magnet 21 was changed. The results are summarized in FIG. The intervals were 1 mm and 2 mm, the air supply pressure was 0.15 MPa, and the rest was the same as in Experiment 1. From the result of FIG. 7, the polishing amount showed a larger value when the interval was 1 mm. The surface roughness showed a larger value at 0.15 MPa when the interval was 1 mm, but was about the same at 0.25 MPa.

[Experiment 3]
When the amount of magnetic particles was changed, the effect of polishing time on the surface roughness and the amount of polishing was investigated. The results are summarized in FIG. The amount of magnetic particles was 4 g and 8 g, the air supply pressure was 0.15 MPa, and the other parts were the same as in Experiment 1. From the results shown in FIG. 8, no tendency was observed depending on the amount of magnetic particles.

[Experiment 4]
The effect of the polishing time on the surface roughness and the amount of polishing when the polishing time was changed was investigated. The result of the surface roughness is shown in FIG. 9 (A), and the result of the polishing amount is shown in FIG. 9 (B). The polishing time was 10 to 50 seconds, the air supply pressure was 0.15 MPa, and other than that, it was the same as in Experiment 1. From the result of FIG. 9, the polishing amount showed a larger value when the interval was 1 mm. The surface roughness showed a larger value at 0.15 MPa when the interval was 1 mm, but was about the same at 0.25 MPa. It can be seen that the longer the time, the smaller the surface roughness and the larger the amount of polishing.

[Experiment 5]
An experiment was conducted on the surface pressure of the object to be polished 1 due to the difference in the tip shape of the magnet 21. The results are summarized in FIG. A is a case where the magnet tip used in Experiment 1 is a flat magnet (see FIG. 1) (length 18 mm, width 12 mm), and b is a case where a part of the magnet tip is a convex portion (length 10 mm, width 10 mm). 12 mm). As shown in FIG. 10, when a part of the tip of the magnet is made a convex portion, the air supply pressure is concentrated per unit area, so that the pressure is higher.

From the above experiments 1 to 5, it was possible to provide a magnetic polishing method and a magnetic polishing apparatus capable of realizing highly efficient and highly accurate polishing even when polishing an object to be polished made of a hard material. Specifically, the N-pole magnet 21N and the S-pole magnet 21S arranged at positions sandwiching the object to be polished 1 are pressed toward the object to be polished 1 while the magnets 21 and the object to be polished 1 are relative to each other. Since it is moved, the surface of the object to be polished 1 can be polished with high efficiency and high accuracy.

1 Polished body 2 Magnetic polishing agent 21 Magnet 21N N-pole magnet 21S S-pole magnet 30 Magnetic polishing device 31 Polished body mounting part 31a Mounting auxiliary member 32 Pressurizing device 33 Relative moving mechanism 33a Swing mechanism 33b Moving mechanism 34 Rotating device F pressure

Claims (5)

A method of magnetically attracting a magnetic polishing agent to a permanent magnet and polishing the surface of the object to be polished with the magnetic polishing agent interposed between the permanent magnet and the object to be polished .
The permanent magnets are a set of N-pole magnets and S-pole magnets arranged at positions sandwiching the object to be polished and attracting each other .
The magnetic polishing agent contains polishing particles and magnetic particles larger than the polishing particles, and the magnetic particles have an average particle size of 0.5 μm or more and 500 μm or less.
Each magnet is subjected to the subject by a pressurizing device for pneumatically pressurizing the N-pole magnet toward the object to be polished and a pressurizing device for pneumatically pressurizing the S-pole magnet toward the object to be polished. A magnetic polishing method characterized in that each magnet and the object to be polished are relatively moved while being pressurized toward the object to be polished. The relative movement is the rotation of the object to be polished or the rotation of each magnet, and / or the vibration or swing of the object to be polished or the vibration or rocking of each magnet, according to claim 1. Magnetic polishing method. The magnetic polishing method according to claim 1 or 2 , wherein the object to be polished is a rod-shaped workpiece. A device that magnetically attracts a magnetic polishing agent to a permanent magnet and polishes the surface of the object to be polished with the magnetic polishing agent interposed between the permanent magnet and the object to be polished .
An N-pole magnet consisting of a set of permanent magnets that are arranged at positions sandwiching between the object-mounted portion to which the object to be polished is attached and the object to be polished that is attached to the object to be polished and attract each other. And an S-pole magnet, a pressurizing device for pneumatically pressurizing the N-pole magnet toward the object to be polished, and a pressurizing device for pneumatically pressurizing the S-pole magnet toward the object to be polished. A relative moving mechanism for relatively moving each magnet and the object to be polished is provided .
The magnetic polishing agent for polishing the surface of the object to be polished contains polishing particles and magnetic particles larger than the polishing particles, and the magnetic particles have an average particle size of 0.5 μm or more and 500 μm or less . A featured magnetic polishing device. The relative movement mechanism is a rotating device that rotates the object to be polished or each magnet, and / or a vibration / swing device that vibrates or swings the object to be polished, or a vibration that vibrates or swings each magnet. The magnetic polishing device according to claim 4 , which is a rocking device.

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