JP2007167968A - Mirror polishing method and mirror polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mirror polishing method and a mirror polishing apparatus capable of improving the flatness of the entire surface in polishing for finishing the surface to be polished to a mirror surface, and capable of performing polishing that can improve the flatness in a short time. Provided An object to be polished (sample 1) is fixed to a support base 2, a polishing tool 3 is made to face the sample 1, and a magnetic polishing liquid 4 is supplied between the two. Nonmagnetic abrasive grains are mixed in the magnetic polishing liquid 4 and a thickener such as α cellulose is mixed. The polishing tool 3 is attached to the shaft end of the planetary gear 30, and a plurality of polishing tools 3 face the sample 1. In the planetary gear mechanism, a plurality of planetary gears 30 are arranged outside the sun gear 31, and an internal gear 32 is meshed further outside, and the planetary gear mechanism is driven by the drive motor 10 linked to the shaft portion of the sun gear 31. Therefore, the polishing tool 3 can perform two movements of rotation and revolution, and the movement with respect to the surface of the sample 1 can be averaged, so that variation in polishing action can be reduced.
[Selection] Figure 1

Description

  The present invention relates to a mirror polishing method and a mirror polishing apparatus for polishing a surface of a precision machine component or a mold to a mirror surface, and more specifically, a polishing tool is made to face a polishing object, and these The present invention relates to an improvement in performing fluid polishing in the presence of a magnetic polishing liquid in the vicinity of the substrate.

  As a technique for finishing the surface to be polished into a mirror surface, in general, lapping or lapping is performed in which an abrasive in which loose abrasive grains are dispersed is rubbed between the polishing object and a lapping surface. Polishing is performed using finer abrasive grains and performing a rubbing operation with a polishing object with a soft tool called a polishing pad.

  Non-contact polishing technology includes float polishing, which is performed by rotating the tin plate and the object to be polished simultaneously in a polishing solution in which a fine polishing agent is turbid, and polishing with the fluid pressure of the polishing solution interposed between them. This is a technique that slightly raises the object and proceeds with the polishing agent in the polishing liquid.

  Further, a technique of magnetic polishing in which polishing is performed by applying a magnetic field is well known, for example, as shown in Patent Documents 1 and 2. Patent Document 1 proposes a technique that improves the performance of the polishing liquid by adjusting dispersed particles in the magnetic polishing liquid, and can be applied to precise polishing and finishing. In Patent Document 2, the behavior of polishing is improved by causing the relative movement between the particle brush made of magnetic abrasive grains and the object to be polished appropriately, and by coating the magnetic abrasive grains with a nonmagnetic layer. There are proposals of techniques that can be applied to smooth polishing and finishing. Such magnetic polishing has a merit that it can perform polishing without stress even for a polishing object having low strength because it can perform so-called non-contact polishing, and is preferred for precision finishing applications.

In magnetic polishing, magnetic abrasive grains (particle brushes), that is, grinding tools, are activated by a magnetic field, so that polishing to be polished has a property of favorably progressing at a facing portion where magnetic poles of a magnetic field generation source face each other. Therefore, the magnetic field generation source is, for example, a permanent magnet, which is assembled to a polishing tool and rotated by a driving source, and a mirror polishing is performed in which a magnetic polishing liquid is present between a polishing target and a polishing target to perform fluid polishing. There is a technology.
JP 2002-170791 A JP 2002-283216 A

  However, the conventional mirror polishing technique has the following problems. That is, since the polishing tool provided with the permanent magnet faces the object to be polished and is rotated by the driving source, the particle brush is well generated in the vicinity of the permanent magnet and the density is high. As a result, the surface polishing of the object to be polished becomes uneven and there is a problem that it is difficult to finish the entire surface flat.

  The present invention solves the above-described problems. The purpose of the present invention is to polish the surface of the object to be polished into a mirror surface by improving the flatness of the entire surface and polishing that can improve the flatness. An object of the present invention is to provide a mirror polishing method and a mirror polishing apparatus that can be performed in a short time.

  In order to achieve the above-described object, the mirror polishing method according to the present invention is a mirror polishing method in which a polishing tool is made to face an object to be polished and a magnetic polishing liquid is present around the polishing tool to perform fluid polishing. The polishing tool is provided with a magnetic field generation source that generates a magnetic field on the opposite side of the object to be polished, and is linked to a first driving means that performs a motion operation of a predetermined locus on the plane. The magnetic polishing liquid is linked between the polishing tool and the object to be polished, and nonmagnetic abrasive grains are mixed in the magnetic polishing liquid. The first driving means is activated to cause the polishing tool to move in a predetermined locus on the plane, and the second driving means is activated to cause the polishing object to move in a predetermined locus on the plane. At this time, the magnetic field source And to perform fluid polishing added temporally constant or fluctuating magnetic fields in the polishing liquid.

  Further, the mirror polishing apparatus according to the present invention includes a polishing tool having a magnetic field generation source facing the object to be polished, and a first driving unit that performs a motion operation of a predetermined locus on a plane in association with the polishing tool. A second driving means for performing a motion movement of a predetermined locus on a plane in cooperation with the object to be polished, and a supply means for supplying a magnetic polishing liquid to a gap between the polishing tool and the object to be polished. Mixes non-magnetic abrasive grains, activates the supply means to cause the magnetic polishing liquid to be present between the polishing bite and the object to be polished, and activates the first driving means to cause the polishing bite to have a predetermined locus on a plane. The second driving means is activated to cause the polishing object to move in a predetermined locus on the plane, and a magnetic field generation source applies a magnetic field that is constantly or fluctuating in time to the magnetic polishing liquid. Configured to add.

  The first drive means has a planetary gear mechanism in which a plurality of planetary gears are engaged with the outside of the sun gear and an internal gear is further engaged with the outside, and a polishing tool is attached to at least one of the planetary gears. The polishing tool may be configured to perform a rotation operation and a revolution operation by driving the sun gear with a drive source. Furthermore, it is preferable that the grinding tool is attached to each planetary gear.

  The magnetic polishing liquid used in each invention is based on a fluid in which 10 to 95 wt% of ferromagnetic particles having a particle diameter of 1 to 80 μm are dispersed in a dispersion medium such as water or kerosene having a kinematic viscosity of about 0.01 to 100 mm 2 / s. In addition, spherical magnetite particles having a particle diameter of 10 to 50 nm are mixed with a composite fluid in which 5 to 90 wt% of a fluid uniformly dispersed in a dispersion medium such as water or kerosene having electrical insulation properties is mixed with a particle diameter of 0.01 to 100 μm. The non-magnetic abrasive grains are mixed, and a fibrous substance such as α-cellulose or a resin such as polyvinyl alcohol is mixed as a thickener in an amount of 5 to 90 wt%.

  Therefore, in the present invention, the polishing tool has a magnetic field generation source, and the first driving means performs a predetermined locus motion on the plane, and the polishing object performs the predetermined locus motion on the plane by the second driving means. . A magnetic polishing liquid exists between the polishing tool and the object to be polished. The magnetic polishing liquid contains non-magnetic abrasive grains, and a magnetic field generation source applies a time-dependent or variable magnetic field to the magnetic polishing liquid. Then, magnetic clusters are generated in the magnetic polishing liquid. Specifically, in the composition as described above, a large number of ferromagnetic particles (for example, iron particles) and magnetite particles are aggregated by a magnetic attractive force to form a magnetic class. Since the magnetic class is along the magnetic flux, a large number of needles stand in opposition to the object to be polished, so that the abrasive grains present in the magnetic polishing liquid are pressed against the surface of the object to be polished. In addition, since there are abrasive grains entangled in the magnetic class, they are also pressed against the surface to be polished.

  In this state, the polishing tool and the object to be polished move relative to each other, whereby the abrasive grains move while contacting the surface of the object to be polished. For this reason, an abrasive grain grinds the convex part of the surface of grinding | polishing object, and a smoother surface is obtained. At this time, the polishing bite does not simply rotate, but moves with a predetermined trajectory on the plane, so that the movement relative to the surface of the object to be polished is averaged, and further, the side of the object to be polished also moves about the plane. The relative movement of the surface increases, so that the dispersion of the polishing action can be reduced, and the entire surface can be sufficiently polished by the magnetic cluster.

  Further, in the configuration in which a plurality of polishing tools face the object to be polished, since the magnetic cluster performs the polishing action in each, the polishing action area per unit time is widened, and the polishing speed is increased.

  In the mirror polishing according to the present invention, the polishing tool has a magnetic field generation source, and the first drive means performs a motion operation of a predetermined locus on the plane, so that the movement with respect to the surface of the polishing object is averaged, and the polishing object is In addition, since the second drive means performs a motion movement of a predetermined trajectory on the plane, the relative movement between the two increases, so that variation in the polishing action can be reduced, and the entire surface can be sufficiently polished by the magnetic cluster. As a result, in the polishing for finishing the surface to be polished into a mirror surface, the entire surface can be polished with improved flatness.

  In the configuration in which a plurality of polishing tools face the object to be polished, since the magnetic cluster performs the polishing action in each of them, the area of the polishing action per unit time is widened and the polishing speed is increased. Therefore, polishing that can improve the flatness can be performed in a short time. Of course, since the polishing is performed by the magnetic cluster, the polishing can be performed without applying a large stress to the object to be polished.

  FIG. 1 shows a preferred embodiment of the present invention. In the present embodiment, the mirror polishing apparatus fixes the object to be polished (sample 1) to the support base 2 and causes the plurality of polishing tools 3 to face the sample 1 in a non-contact manner between them. Presents the magnetic polishing liquid 4. Each polishing tool 3 is caused to generate a magnetic field and to move in a predetermined locus, and also to vibrate the supporting stand 2 in a predetermined locus so that fluid polishing is performed by a magnetic cluster generated in the magnetic polishing liquid 4. It has become.

  The magnetic polishing liquid 4 contains non-magnetic abrasive grains. Specifically, ferromagnetic particles having a particle diameter of 1 to 80 μm in a dispersion medium such as water or kerosene having a kinematic viscosity of about 0.01 to 100 mm 2 / s. 5 to 90 wt% of a fluid in which spherical magnetite particles having a particle diameter of 10 to 50 nm are uniformly dispersed in a dispersion medium such as water or kerosene having electrical insulation properties is mixed with a fluid in which 10 to 95 wt% is dispersed. The composite fluid is mixed with non-magnetic abrasive grains having a particle diameter of 0.01 to 100 μm, and further mixed with 5 to 90 wt% of a fibrous substance such as α cellulose or a resin such as polyvinyl alcohol as a thickener. The magnetic polishing liquid 4 is supplied to a space between the sample 1 and the polishing tool 3 by a supply means (not shown).

  The support 2 is assembled to the base 7 of the traverse device 6 via the spring screw 5. Then, the traverse device 6 is assembled to the vibration table 8. A contact type load cell 9 is disposed at a portion where the spring screw 5 is mounted. That is, the vertical position of the support base 2 is initially set by moving the base 7 of the traverse device 6, and vibration of a predetermined locus is given by the vibration base 8. This predetermined trajectory is to give a motion such as, for example, drawing an 8-shaped trajectory on the surface opposite to the polishing tool 3 and vibrating. The operation state is detected by the load cell 9.

  Each of the plurality of polishing tools 3 is attached to the planetary gear 30 and is configured as a so-called planetary gear mechanism that rotates and revolves. As shown in FIG. 2, this planetary gear mechanism has a plurality of planetary gears 30 arranged and meshed outside the central sun gear 31, and an internal gear 32 arranged and meshed further outside. Each planetary gear 30 is assembled to a carrier 33 and rotatably supported, and an internal gear 32 is fixed to a support plate 34 to support the whole. The support plate 34 is fixed to a mounting portion (not shown) above the support table 2, and a plurality of polishing tools 3 are directed toward the support table 2 from above. The sun gear 31 is linked to the drive motor 10 to drive it.

  The drive motor 10 may be a rotary drive mechanism such as a drilling machine, a lathe, an NC lathe, or a milling machine. By attaching the shaft portion of the sun gear 31 to the chuck portion 11 connected to the output shaft of the drive motor 10, the aspect gear 31 can be attached and detached.

  The polishing tool 3 has a permanent magnet 36 concentrically embedded in a cylindrical body 35 made of a non-magnetic material, and is set so that the permanent magnet 36 faces the sample 1 (target to be polished). That is, the permanent magnet 36 acts as a magnetic field generation source that generates a magnetic field by applying a magnetic field to the magnetic polishing liquid 4 between the facing magnet 1 and the facing sample 1. The magnetic field generation source is not limited to the permanent magnet 36, and for example, an electromagnet or the like can be preferably applied as long as it can act on the magnetic polishing liquid 4. The generation of the magnetic field does not have to be stationary in time, and a magnetic field that varies in time may be generated.

  The vibration table 8 has a drive source (not shown) and adopts a configuration that vibrates in a predetermined locus on the surface opposite to the polishing tool 3. The vibration operation sets a plurality of vibration modes. The vibration operation by the vibration table 8 is a motion operation that moves around a figure-eight locus or a motion operation that simply rotates around a fixed point or reciprocally vibrates on the opposite surface to the shaft portion of the sun gear 31. There are a plurality of vibration modes such as a movement operation, and these are appropriately selected or combined during the polishing operation. Note that the vibration table 8 may be configured to perform a motion operation including longitudinal vibration in the axial direction of the polishing tool 3.

  When the sample 1 is polished, first, the sample 1 is fixed to the support 2, the positional relationship of the sample 1 is initially set with respect to the upper polishing tool 3, and the magnetic polishing liquid 4 is supplied between the two. Start. Then, the drive motor 10 and the vibration table 8 are activated to cause both the polishing tool 3 and the sample 1 (support table 2) to move and move the magnetic polishing solution 4 in a stirring state. At this time, a magnetic field acts on the magnetic polishing liquid 4 by a magnetic field generation source (permanent magnet 36), and a magnetic flux is generated between the sample 1 and the polishing bit 3 as shown in FIG. A magnetic cluster 12 is generated in FIG.

  That is, since the permanent magnet 36 is embedded in the polishing tool 3, a magnetic field acts, a magnetic flux is generated between the permanent magnet 36 and the sample 1, and ferromagnetic particles (for example, iron particles) and magnetite particles are attracted by magnetic attraction. Many aggregate to form magnetic clusters 12. Since the magnetic cluster 12 is along the magnetic flux, a large number of needles are arranged in opposition to the sample 1. In the magnetic polishing liquid 4, α-cellulose 13 added as a thickener occupies a position in a woven state between the magnetic clusters 12, and further, nonmagnetic abrasive grains 14 are added. Some are entangled, but many of them are present on the surface of the sample 1 because the liquid is in a stirred state. Therefore, the abrasive grains 14 present in the magnetic polishing liquid 4 are pressed against the surface of the sample 1 by the magnetic clusters 12 arranged in a needle shape and the α cellulose 13 in a woven state. In addition, since there are abrasive grains 14 entangled in the magnetic clusters 12 and α-cellulose 13, they are also pressed against the surface of the sample 1.

  In this state, since both the polishing tool 3 and the sample 1 (support 2) move with each other, the abrasive grains 14 move while in contact with the surface of the sample 1 due to relative movement. The projections 14 are ground by the abrasive grains 14 to obtain a smoother surface. That is, mirror polishing can be performed.

  When the magnetic field is stationary, the magnetic clusters 12 stand in line along the magnetic flux, and the alignment state is maintained by the magnetic force, so that the abrasive grains 14 can hit the surface (polishing surface) of the sample 1 appropriately to perform polishing. Further, when the magnetic field is fluctuating, the magnetic cluster 12 swings, and at this time, the abrasive grains 14 hit the polishing surface appropriately and can be polished. Thus, although the polishing tool 3 does not have an apparently effective grinding blade with respect to the sample 1, it can be polished by the pressing action of the magnetic cluster 12 and the α cellulose 13, and fluid polishing can be performed.

  Since the magnetic polishing liquid 4 contains α-cellulose 13 as a thickener, the added thickener acts to hold the magnetic cluster 12, and as a result, many abrasive grains 14 come into contact with the surface of the sample 1. The situation can be promoted and polishing can be performed with high efficiency.

  Here, according to the mirror polishing according to the present invention, since the polishing bit 3 is attached to the planetary gear mechanism, two movements of rotation and revolution can be performed, so that movement relative to the surface of the sample 1 is averaged. At this time, since the support base 2 also vibrates along a trajectory that draws a figure of 8 on the plane, the relative movement between the two increases, so that variation in the polishing action can be reduced, and the magnetic cluster 12 can be sufficiently applied to the entire surface. Can be polished. As a result, in the polishing for finishing the surface of the sample 1 into a mirror surface, the entire surface can be polished with improved flatness, and a smooth flat surface with high flatness can be obtained.

  Since the plurality of polishing tools 3 face the sample 1, the magnetic cluster 12 performs the polishing action in each of them, so that the area of the polishing action per unit time is widened and the polishing speed is increased. . Therefore, polishing that can improve the flatness can be performed in a short time. Of course, since the polishing is performed by the magnetic cluster 12, the sample 1 can be polished without applying a large stress.

  The sample was polished using the mirror polishing apparatus shown in FIG. That is, in order to demonstrate the effect of the present invention, the sample was polished under predetermined polishing conditions, and the surface roughness Ra (arithmetic average roughness) and Ry (maximum roughness) were evaluated for the sample. The magnetic polishing liquid had the composition shown in Table 1, and the evaluation test was performed by a conventional method, that is, a polishing by simply rotating one polishing tool, which was used as a comparative example.

Here, the magnetic polishing liquid contains, in its composition, alumina having a particle diameter of 0.05 μm as non-magnetic abrasive grains, and further contains α-cellulose as a thickener. The sample was made of brass and flat, and was polished under various conditions shown in Table 2. As a result, surface roughness Ra and Ry shown in the same table were obtained.

  That is, in the configuration according to the present invention (planetary gear type), the permanent magnet 36 as the magnetic field generation source has a diameter of 10 mm and the surface magnetic flux density is 240 mT. In the conventional configuration (rotary type), the permanent magnet has a diameter of 8 mm. The surface magnetic flux density is 520 mT. Further, the rotational speed of the drive motor 10 is 800 rpm, the polishing time is 1 hour, and the vibration table 8 performs a motion operation (vibration) that moves around an 8-shaped locus on the opposite side of the shaft of the sun gear 31. The amplitude was 10 mm and the vibration was 20 times per minute. The surface roughness Ra and Ry after polishing shown in Table 2 are values in the range where the sweep length is 0.1 mm to 1 mm.

  As a result, the surface roughness Ra and Ry are 0.0066 μm and 0.048 μm in the present invention, whereas in the comparative example, they are 0.009 μm and 0.092 μm, and the maximum roughness Ry is approximately 1 / It was confirmed that polishing can be performed with a clearly increased flatness. Since the polishing time is the same as that of the comparative example, it can be said that the polishing rate is high, and the usefulness of the present invention was confirmed.

Next, Table 3 shows the results of an evaluation test with a sweep length of 20 mm, and the polishing conditions are the same as those shown in Table 2. 4 shows a polishing waveform in a 20 mm sweep, (a) is a polishing waveform according to the present invention, and (b) is a polishing waveform according to a conventional method.

  In the evaluation test in which the sweep length is 20 mm, as shown in Table 3 and FIG. 4, the surface roughness Ra and Ry are 0.157 mm and 1.04 mm in the present invention, whereas they are 0 in the comparative example. It was confirmed that the maximum roughness Ry could be reduced to about 1/3, polishing that could clearly increase the flatness, and mirror finish could be performed satisfactorily.

  As described above, according to the mirror polishing according to the present invention, the polishing waveform is smooth, the surface roughness Ra, Ry can be set to a sufficiently low value, and the polishing rate is further increased. Therefore, polishing with high flatness can be performed in a short time, and mirror polishing can be performed with sufficient surface roughness over the entire surface to be polished.

1 is a configuration diagram showing a preferred embodiment of a mirror polishing apparatus according to the present invention. It is sectional drawing (a) and top view (b) explaining the grinding | polishing tool | tool shown in FIG. It is explanatory drawing which shows the fluid grinding | polishing by a magnetic cluster. It is a graph which shows surface roughness, (a) is the grinding | polishing waveform based on this invention, (b) is the grinding | polishing waveform by a conventional system.

Explanation of symbols

1 Polishing target (sample)
2 Support table 3 Polishing tool 4 Magnetic polishing solution 5 Spring screw 6 Traverse device 7 Base 8 Vibration table 9 Load cell 10 Drive motor 11 Chuck part 12 Magnetic cluster 13 α cellulose 14 Abrasive grain 30 Planetary gear 31 Sun gear 32 Internal gear 33 Carrier 34 Support plate 35 Cylinder 36 Permanent magnet (magnetic field source)

Claims (4)

A polishing method in which a polishing tool is made to face a polishing object, and a fluid polishing is performed in the presence of a magnetic polishing liquid in the periphery of the polishing tool,
The polishing tool is provided with a magnetic field generation source that generates a magnetic field on the opposite side of the polishing object, and is linked to a first driving unit that performs a driving operation of a predetermined locus on the plane. The magnetic polishing liquid is linked between the polishing tool and the object to be polished, and the magnetic polishing liquid is non-magnetic abrasive grains. And the first driving means is activated to cause the polishing tool to move along a predetermined locus on the plane, and the second driving means is activated to determine the polishing object on the plane as well. A mirror polishing method characterized in that a moving motion of a locus is performed, and fluid polishing is performed by applying a stationary or fluctuating magnetic field in time to the magnetic polishing liquid by the magnetic field generation source. A polishing tool having a magnetic field generation source facing the object to be polished, first driving means for performing a motion operation of a predetermined locus on the plane in association with the polishing tool, and on a plane in association with the object to be polished Second driving means for performing a movement operation of a predetermined locus, and supply means for supplying a magnetic polishing liquid to a gap between the polishing bit and the object to be polished,
Nonmagnetic abrasive grains are mixed in the magnetic polishing liquid, the supply means is activated to cause the magnetic polishing liquid to exist between the polishing bit and the object to be polished, and the first driving means is activated. The polishing tool is moved in a predetermined locus on a plane, the second driving means is activated to move the polishing object in a predetermined locus on the plane, and the magnetic field generating source performs the magnetic movement. A mirror polishing apparatus, characterized in that a magnetic field that is constant or fluctuating in time is applied to a polishing liquid.   The first drive means has a planetary gear mechanism that meshes a plurality of planetary gears outside the sun gear and further meshes an internal gear on the outside, and the polishing tool is attached to at least one of the planetary gears. The mirror polishing apparatus according to claim 2, wherein the polishing tool is rotated and revolved by attaching and driving the sun gear by a driving source.   4. The mirror polishing according to claim 3, wherein the polishing tool is attached to each of the planetary gears, and the polishing tool is rotated and revolved by driving the sun gear with a driving source. apparatus.

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