Fluid polishing apparatus and fluid polishing method

Abstract

To provide a technique for further improving the polishing efficiency in fluid polishing.SOLUTION: A fluid polishing device comprises: a shaft body which can rotate around a shaft line extending in a prescribed direction; a main magnetic body in which a conductive layer having conductivity is formed on a portion or the whole of a cylindrical magnet surrounding the shaft line and is provided so as to be rotatable driven by the shaft body; a sub magnetic body which is made of a cylindrical magnetic material that surrounds the shaft line and has a diameter different from that of the main magnetic body, and is provided so as to be rotatable driven by the shaft body in a state of being received inside the main magnetic body or receiving the main magnetic body therein; and an electrical field path in which one of electrode poles in a pair is connected to the conductive layer of the main magnetic body, meanwhile the other is provided at a prescribed distance from the main magnetic body, and which becomes a conductive path that generates an electrical field involving electric conduction into between the electrode poles.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fluid polishing apparatus for polishing an object to be processed by using a processing fluid. [Background technology]

[0002] Fluid polishing involves polishing the surface of the workpiece by displacing the workpiece relative to the tool body, which is made of a magnetic body, with a processing fluid containing abrasive grains interposed between the workpiece and the tool body. In recent years, a method has been proposed to improve polishing efficiency by polishing under magnetic and electric fields (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-116722 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, simply performing polishing under a magnetic field and an electric field does not necessarily result in a sufficiently high polishing efficiency, and there is still room for improvement.

[0005] The present invention has been made to solve such problems, and an object of the present invention is to provide a technique for further improving the polishing efficiency in fluid polishing. [Means for solving the problem]

[0006] In a first aspect for solving the above problem, there is provided a magnetic recording medium having a shaft body rotatable around an axis extending in a predetermined direction, a main magnetic body including a cylindrical magnet surrounding the axis and rotatably provided to move with the shaft body, a sub-magnetic body including a cylindrical magnetic body surrounding the axis and rotatably provided to move with the shaft body while being spaced apart from the main magnetic body in the direction in which the shaft body extends, and a pair of electrodes, one of which is connected to the conductive layer of the main magnetic body while the other is provided at a position spaced a predetermined distance from the main magnetic body, and a conductive layer is provided between the electrodes. and an electric field path which serves as a current path for generating an electric field associated with a current, the sub-magnetic body being formed with an outer diameter that is the same as the outer diameter of the main magnetic body or that is approximately the same as the outer diameter of the main magnetic body and less than a predetermined threshold value, and a processing fluid containing non-magnetic and non-conductive abrasive grains is interposed between an area formed by the main magnetic body and the sub-magnetic body on the side side of the shaft body and a processed surface of the workpiece arranged opposite this area, and the shaft is rotated under a magnetic field generated by the main magnetic body and an electric field generated by the electric field path, thereby achieving magnetic fluid polishing of the workpiece.

[0007] In the fluid polishing apparatus in this aspect, the magnetic field generated by the magnet forms magnetic clusters centered on the magnetic particles in the processing fluid along the direction of the magnetic field lines leading to the workpiece.

[0008] Here, the magnetic field lines of the magnet tend to spread in the axial direction due to the influence of the sub-magnetic body, so the magnetic particles are distributed so as to spread in the axial direction along the magnetic field lines, and are gathered on the magnet side due to the influence of the magnetic field. Meanwhile, the abrasive grains are displaced to the area of ​​the weak magnetic field, i.e., the surface to be machined, due to the magnetic buoyancy (the force that displaces the non-magnetic body to the area of ​​the weak magnetic field), but they try to displace to the area of ​​the weak magnetic field, such as one end side of the shaft body in the main magnetic body and the other end side of the shaft body in the sub-magnetic body. In this embodiment, the electric field generated by the electric field path can apply a force to the abrasive grains to aggregate along the electric field lines against such displacement, so that the displacement of the abrasive grains in the processing fluid as described above can be suppressed by this force, and the number of abrasive grains present on the surface to be machined can be prevented from decreasing.

[0009] Furthermore, in the processing fluid, agglomerates of abrasive grains are formed due to the effect of the electric field generated by the electric field path, and the apparent viscosity of the processing fluid increases locally, so that the magnetic clusters are pressed against the workpiece with even stronger force. This is because the non-magnetic and non-conductive abrasive grains are affected by the dielectric polarization caused by the electric field, causing a bias in the electric charge on a particle-by-particle basis, and as a result, adjacent particles tend to aggregate together in order to cancel out this biased electric charge.

[0010] By rotating the main magnetic body and the sub-magnetic body together with the shaft in the above-mentioned state, the surface of the workpiece facing the area formed by the magnetic bodies on the side of the shaft is polished by the abrasive grains in the processing fluid. At this time, the magnetic clusters are distributed along the axial direction, and the abrasive grains can be widely arranged and applied to the surface of the workpiece, thereby further increasing the polishing efficiency of the fluid polishing.

[0011] In this aspect, the other electrode in the electric field path may be provided at a position spaced apart from the main magnetic body by a predetermined distance, and may be provided at a position spaced apart inward and outward directions between the main magnetic body and the workpiece, for example. In this case, if the workpiece is made of a conductive material, the other electrode may be provided in contact with the workpiece, so that the workpiece itself functions as an electrode.

[0012] In this aspect, the magnetization direction of the magnet in the main magnetic body is not particularly limited, and it is possible to set it as in the second or third aspect shown below.

[0013] In a second aspect, the main magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in an axial direction, which is the direction in which the axis extends.

[0014] In this aspect, the magnetic clusters can be distributed in the main magnetic body and the sub magnetic body in the direction in which the axis extends.

[0015] In a third aspect, the main magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in an inward and outward direction that intersects with the axis.

[0016] In this aspect, the magnetic clusters can be distributed in the axial direction along the magnetic field lines extending from one side to the other on the side surfaces of the main magnetic body and the sub-magnetic body.

[0017] In the second and third aspects, the sub-magnetic body may be a magnetic body made of a material that affects a magnetic field, but a magnet made by magnetizing a magnetic body may also be used.

[0018] In this case, it is possible to take the fourth and fifth steps shown below. In a fourth aspect, the sub-magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body but with an opposite arrangement of magnetic poles.

[0019] In this aspect, if the main magnetic body and the sub magnetic body are magnetized in the axial direction, the same magnetic poles are arranged facing each other with an axial gap between them on the side of the shaft body, and independent axial magnetic field line loops are formed for each, so that magnetic clusters can be distributed widely along these magnetic field lines in the direction in which the axis extends.

[0020] On the other hand, if the main magnetic body and the sub magnetic body are magnetized in the inward and outward directions, opposite magnetic poles are arranged at intervals in the axial direction on the side of the shaft body, so that magnetic clusters can be distributed widely in the axial direction along the magnetic field lines extending from one side to the other.

[0021] In a fifth aspect, the sub-magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in a direction intersecting the magnetization direction of the main magnetic body and such that the area facing the main magnetic body on the side of the shaft body has the same magnetic polarity as the main magnetic body.

[0022] In this aspect, both magnetic bodies are arranged on the side of the shaft body so that the same magnetic poles face each other in the axial direction, and independent axial magnetic field line loops are formed, so that magnetic clusters can be distributed widely in the axial direction along these magnetic field lines.

[0023] Moreover, the other electrode in the electric field path may be provided on the sub-magnetic body side, in which case it is possible to adopt the sixth aspect shown below.

[0024] In a sixth aspect, the sub-magnetic body has a conductive layer formed on part or the entirety of a cylindrical magnetic body and is electrically insulated from the main magnetic body, and the electric field path is such that the other electrode is connected to the conductive layer of the sub-magnetic body.

[0025] In this aspect, the main magnetic body and the sub magnetic body function as electrodes arranged at a distance from each other, and an electric field can be generated between the two magnetic bodies. As a result, the pair of electrodes is integrated with the fluid polishing device, so that it is possible to reduce the effort of providing the other electrode at a distance from the main magnetic body, for example, by providing the other electrode on the workpiece each time polishing is performed.

[0026] In addition, in each of the above aspects, the seventh aspect described below may be adopted. In a seventh aspect, the device includes a power supply unit that applies a voltage to the electric field path, and the power supply unit generates an electric field strength of 2.0 kV / mm or less between electrodes in the electric field path by applying a voltage to the electric field path.

[0027] In this aspect, an electric field suitable for forming magnetic clusters in which abrasive grains are concentrated on the surface side of the workpiece can be generated via the electric field path without current flowing between the electrodes due to dielectric breakdown.

[0028] In order to solve the above problem, a fluid polishing method according to an eighth aspect of the present invention includes a shaft body rotatable about an axis extending in a predetermined direction, a main magnetic body including a cylindrical magnet surrounding the axis and rotatably provided to move with the shaft body, a sub-magnetic body including a cylindrical magnetic body surrounding the axis and rotatably provided to move with the shaft body while being spaced apart from the main magnetic body in the extension direction of the shaft body, and a pair of electrodes, one of which is connected to the conductive layer of the main magnetic body and the other of which is located a predetermined distance from the main magnetic body. and an electric field path which serves as a current path for generating an electric field associated with current passing between these electrodes, and in which a processing fluid containing non-magnetic and non-conductive abrasive grains is interposed between an area formed by the main magnetic body and the sub-magnetic body on the side side of the shaft and a processing surface of the workpiece arranged opposite this area, the shaft is rotated under the magnetic field generated by the main magnetic body and the electric field generated by the electric field path, thereby achieving magnetic fluid polishing of the workpiece.

[0029] The fluid polishing method according to this aspect is suitable for implementing fluid polishing using each of the fluid polishing apparatuses described above. [Brief description of the drawings]

[0030] [Figure 1] A front cross-sectional view of a fluid polishing apparatus taken along a plane intersecting an axial direction (1) [Diagram 2]A front cross-sectional view (2) of a fluid polishing apparatus taken along a plane intersecting the axial direction. [Diagram 3] A front cross-sectional view (3) of a fluid polishing apparatus taken along a plane intersecting the axial direction. [Figure 4] A front cross-sectional view (4) of a fluid polishing apparatus taken along a plane intersecting the axial direction. [Diagram 5] A front cross-sectional view (5) of a fluid polishing apparatus taken along a plane intersecting the axial direction. [Figure 6] A front cross-sectional view (6) of a fluid polishing apparatus taken along a plane intersecting the axial direction. [Figure 7] A diagram showing the distribution of magnetic and electric field lines between the main magnetic body and the sub-magnetic body, and the state of the magnetic clusters that occur between them (1) [Figure 8] Diagram (2) showing the distribution of magnetic and electric field lines between the main magnetic body and the sub-magnetic body, and the state of the magnetic clusters that occur between them. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (1) Equipment overview The fluid polishing device 1 is a device for performing fluid polishing on the surface of a workpiece 100 by rotating a processing fluid 200, which is a magnetic fluid containing non-magnetic and non-conductive abrasive grains, relative to the workpiece 100 while being interposed between the workpiece 100 and the fluid.

[0032] (2) Overall structure As shown in Figure 1, the fluid polishing apparatus 1 comprises a shaft body 10 that can rotate around an axis extending in a predetermined direction (up and down in the figure), a main magnetic body 20 and a sub-magnetic body 30 which are cylindrical magnetic bodies that each surround the axis, an electric field path 40 equipped with a set of electrodes, a rotational drive unit 50 that rotates the shaft body 10, a control unit 60 that controls the operation of the entire apparatus, and a power supply unit 70 that applies a voltage to the electric field path 40.

[0033] The shaft body 10 is a cylindrical member extending along an axis and made of a conductive material. The shaft body 10 is electrically insulated from the rotation drive unit 50.

[0034] The main magnetic body 20 is a magnet formed by magnetizing a cylindrical magnetic body in the direction in which the axis extends (hereinafter referred to as the "axial direction"), and is provided so as to be rotatable following the shaft body 10 with the same axis as the center of rotation. Here, the shaft body 10 is magnetized so that one end (the lower end in FIG. 1; the same applies below) is an S pole, and the other end (the upper end in FIG. 1; the same applies below) is an N pole. Note that the main magnetic body 20 may also be magnetized so that the other end of the shaft body 10 is an S pole, and one end is an N pole.

[0035] The main magnetic body 20 has a conductive layer 21 formed over a part or the whole (the whole in this embodiment) of the main magnetic body 20. The conductive layer 21 is made of a material that is soft magnetic, highly conductive, and highly hard, and is formed so as to cover the surface of the main magnetic body 20. In this embodiment, the conductive layer 21 is formed by plating the entire main magnetic body 20 with nickel or chromium.

[0036] Furthermore, this conductive layer 21 only needs to cover at least the area of ​​the surface of the main magnetic body 20 that is connected to the electric field path 40 (the upper end surface 21u connected to the cylindrical body 13 described later) and the area (here, the outer peripheral surface 21o) facing the sub-magnetic body 30 for generating an electric field between the sub-magnetic body 30.

[0037] The sub magnetic body 30 is made of a cylindrical magnetic body formed with an outer diameter that is the same as the outer diameter of the main magnetic body 20 or that is close to the outer diameter and less than a predetermined threshold value (in this embodiment, the same as the outer diameter of the main magnetic body 20). The sub magnetic body 30 is provided rotatably following the shaft body 10 while being spaced apart from the main magnetic body 20 in the axial direction. In this embodiment, the sub magnetic body 30 is disposed closer to one end of the shaft body 10 than the main magnetic body 20.

[0038] The sub-magnetic body 30 is a magnet formed by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body 20 but with the magnetic poles arranged in the opposite direction. Here, one end of the shaft body 10 is magnetized as the N pole and the other end as the S pole. Note that the sub-magnetic body 30 may also be magnetized so that the other end of the shaft body 10 is the N pole and one end as the S pole, in accordance with the magnetic pole arrangement of the main magnetic body 20.

[0039] The sub-magnetic body 30 is formed by forming a conductive layer 31 over a part or the whole (the whole in this embodiment) of the cylindrical magnetic body, and is electrically insulated from the main magnetic body 20. This conductive layer 31 is made of a material that is soft magnetic, highly conductive, and highly hard, and is formed so as to cover the surface of the sub-magnetic body 30. In this embodiment, the conductive layer 31 is formed by plating the entire sub-magnetic body 30 with nickel or chromium.

[0040] It is sufficient that this conductive layer 31 covers only the area of ​​the surface of the sub-magnetic body 30 that is connected to the shaft body 10 (the tip side of the inner surface 31i), the area facing the main magnetic body 20 for generating an electric field between the main magnetic body 20 (here, the outer surface 31o), and the area for connecting these areas (here, the end face 31u or the upper end face 31d on the other end side of the shaft body 10).

[0041] Here, in order to electrically insulate the main magnetic body 20 from the sub-magnetic body 30, an insulating material 11 is provided at least between the main magnetic body 20 and the sub-magnetic body 30. In this embodiment, the insulating material 11 is filled between each magnetic body and between each magnetic body and the shaft body 10.

[0042] The distance between the main magnetic body 20 and the sub-magnetic body 30 is selected so as to achieve the desired distribution of magnetic and electric field lines depending on the magnet parameters (magnetic flux density, magnetic field strength, etc.) and the electric field parameters generated by the electric field path 40 (voltage, electric field strength, etc.).

[0043] The electric field path 40 has one electrode 41 connected to the conductive layer 21 of the main magnetic body 20 and the other electrode 43 located at a position spaced a predetermined distance from the main magnetic body 20, and serves as a current path that generates an electric field when current is passed between these electrodes.

[0044] In this embodiment, a conductive cylindrical body 13 is provided which surrounds the shaft body 10 outside the sub-magnetic body 30 and is disposed adjacent to the conductive layer 21 of the main magnetic body 20 in the axial direction, and one of the electrode elements 41 is connected to this cylindrical body 13. In other words, the main magnetic body 20 is electrically connected to one of the electrode elements 41 via the cylindrical body 13 and the conductive layer 21, and functions as an electrode of the electric field path 40. This electrode element 41 is formed as an electrically conductive brush.

[0045] In this embodiment, the conductive layer 31 of the sub-magnetic body 30 and the shaft body 10 are connected to a side surface at one end of the shaft body 10, and the other electrode element 43 is connected to the other end of the shaft body 10. In other words, the sub-magnetic body 30 is electrically connected to the other electrode element 43 via the shaft body 10, and functions as an electrode of the electric field path 40. Here, the other electrode element 43 is formed as an electrically conductive brush.

[0046] In this electric field path 40, a voltage is applied between a pair of electrodes (each region functioning as an electrode; in this embodiment, the main magnetic body 20 connected to one electrode 41, and the sub-magnetic body 30 connected to the other electrode 43) by a power supply unit 70. In this embodiment, a voltage is applied according to the magnetic field strength of the magnet, the components of the processing fluid 200, the distance from the workpiece 100, etc. In this embodiment, the configuration is such that an electric field strength of 2.0 kV / mm or less is applied, selected so that members (particularly the processing fluid 200) that may be present between the main magnetic body 20 and the sub-magnetic body 30 do not become conductive due to dielectric breakdown.

[0047] A non-conductive magnetic fluid containing non-conductive and non-magnetic abrasive grains is used as the processing fluid 200. In the processing fluid 200, magnetic particles having a particle size of 5 nm to 10 μm are selectively used as the magnetic particles according to the magnetic field strength of the magnet, the distance from the workpiece 100, the composition of the base liquid, and the like.

[0048] The abrasive grains contained in this processing fluid 200 are selected from materials having a dielectric constant at least equal to or greater than that of the base liquid in the magnetic fluid, such as general abrasive grains made of ceramic materials such as alumina or silicon carbide, or super abrasive grains such as diamond or cubic boron nitride (cBN), suitable for the workpiece 100.

[0049] In this embodiment, in addition to the above, a certain amount of fibrous material having a predetermined length is distributed in the processing fluid 200. Specifically, α-cellulose having a length approximately equal to or shorter than the distance to the processing object 100 is distributed. This fibrous material can promote and reinforce the generation of magnetic clusters, which will be described later.

[0050] In the fluid polishing apparatus 1 configured in this manner, the processing fluid 200 is interposed between the region formed by the main magnetic body 20 and the sub magnetic body 30 on the side surface of the shaft body 10 and the surface to be processed of the workpiece 100 arranged opposite this region, and the shaft body 10 is rotated under the magnetic field of the magnet and the electric field of the electric field path 40, thereby achieving magnetic fluid polishing of the workpiece 100. Fig. 1 illustrates an example of a configuration in which the inner peripheral surface of the cylindrical workpiece 100 is processed along the side surfaces of the magnetic bodies.

[0051] Here, the distance between the area formed by the main magnetic body 20 and the sub magnetic body 30 on the side of the shaft body 10 and the processed surface of the workpiece 100 arranged opposite this area is a distance selected (in this embodiment, a distance selected from the range of 0.5 to 2.0 mm; more specifically, 1 mm) so as to achieve the desired distribution of magnetic and electric field lines depending on the parameters of the magnet (magnetic flux density, magnetic field strength, etc.) and the parameters of the electric field generated by the electric field path 40 (voltage, electric field strength, etc.).

[0052] Needless to say, the above-mentioned fluid polishing apparatus 1 can be configured to achieve magnetic fluid polishing by placing the workpiece 100 on a stage and displacing this stage along the x-y axis or the x-yz axis using a displacement mechanism, or by similarly displacing the fluid polishing apparatus 1 using a displacement mechanism.

[0053] (3) Modifications It goes without saying that the present invention is not limited to the above-described embodiment, and various other forms can be adopted as long as they fall within the technical scope of the present invention.

[0054] For example, in the above embodiment, the main magnetic body 20 and the sub magnetic body 30 are magnets formed by magnetizing cylindrical magnetic bodies in the axial direction. However, these magnetic bodies may be magnets magnetized in the inward and outward directions intersecting the axis.

[0055] In the present embodiment, a magnet formed by magnetizing a magnetic body is used as the sub-magnetic body 30. However, the sub-magnetic body 30 does not have to be a magnet as long as it is a magnetic body made of a material that affects the magnetic field, as shown in FIG.

[0056] In this embodiment, the sub-magnetic body 30 is electrically connected to the other electrode element 43 via the shaft body 10, and is configured to function as an electrode separated from the main magnetic body 20 in the axial direction in the electric field path 40. However, the function of the electrode in the electric field path 40 may be performed by the other electrode element 43 itself, and as a specific example, the other electrode element 43 may be arranged with a gap in between in the inner and outer directions, sandwiching the main magnetic body 20 and the workpiece 100, as shown in Fig. 3. In this case, it is preferable to configure one electrode element 41 to be divided into two and connected to the main magnetic body 20 side (cylindrical state 13) and the sub-magnetic body 30 side (shaft body 10), respectively.

[0057] In addition, in this configuration, if the workpiece 100 is made of a conductive material, the other electrode 43 can be placed in contact with the workpiece 100, thereby making the entire workpiece 100 function as an electrode.

[0058] In the above embodiment, the main magnetic body 20 is a magnet formed by magnetizing a cylindrical magnetic body in the axial direction, and the sub magnetic body 30 is a magnet formed by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body 20 and with the magnetic poles arranged in the opposite direction. However, as for these magnetic bodies, as shown in Fig. 4, the main magnetic body 20 may be a magnet formed by magnetizing a cylindrical magnetic body in the inward and outward directions, and the sub magnetic body 30 may be a magnet formed by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body 20 and with the magnetic poles arranged in the opposite direction.

[0059] In this example, the main magnetic body 20 is magnetized so that the inside is an S pole and the outside is an N pole, and the sub magnetic body 30 is magnetized so that the inside is an N pole and the outside is an S pole.

[0060] In the above embodiment, the sub magnetic body 30 is a magnet formed by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body 20 and with the magnetic poles arranged in the opposite direction. However, the sub magnetic body 30 may be a magnet formed by magnetizing a cylindrical magnetic body in a direction intersecting the magnetization direction of the main magnetic body 20 and such that the region facing the main magnetic body 20 on the side of the shaft body 10 has the same magnetic pole as the main magnetic body 20.

[0061] Specifically, as shown in Figure 5, when the inside of the main magnetic body 20 is magnetized so that the inside is an S pole and the outside is an N pole, it is possible to use a magnet as the sub-magnetic body 30, which is a cylindrical magnetic body magnetized in the axial direction and so that the area facing the main magnetic body 20 on the side of the shaft body 10 is magnetized to an N pole, which is the same magnetic pole as the main magnetic body 20.

[0062] In this configuration, the sub-magnetic body 30 may be configured to be a magnet in which the inside of the cylinder is filled with a magnetic body, as shown in FIG.

[0063] Furthermore, in this embodiment, the fluid polishing apparatus 1 is configured to rotate relative to the workpiece 100, but the workpiece 100 may be configured to rotate.

[0064] (4) Effects In the fluid polishing apparatus 1 of the above embodiment, the magnetic field generated by the magnet forms magnetic clusters centered on magnetic particles in the processing fluid along the direction of the magnetic field lines leading to the workpiece 100 (see Figures 7 and 8).

[0065] Here, the magnetic field lines of the magnet tend to spread inward and outward due to the influence of the sub-magnetic body 30, so the magnetic particles are distributed so as to spread in the axial direction along the magnetic field lines, and are gathered on the magnet side due to the influence of the magnetic field. On the other hand, the abrasive grains are displaced to the area of ​​the weak magnetic field, i.e., the surface to be machined, due to magnetic buoyancy (the force that displaces a non-magnetic body to an area of ​​a weak magnetic field), but they try to displace to areas of a weak magnetic field such as one end side (upper) of the shaft body 10 in the main magnetic body 20 and the other end side (lower) of the shaft body 10 in the sub-magnetic body 30. In this embodiment, the electric field generated by the electric field path 40 can apply a force to the abrasive grains to aggregate along the electric field lines against such displacement, so that the displacement of the abrasive grains in the processing fluid 200 as described above can be suppressed by this force, and the number of abrasive grains present on the surface to be machined can be prevented from decreasing (see FIG. 8).

[0066] Furthermore, in the processing fluid 200, agglomerates of abrasive grains are formed due to the effect of the electric field generated by the electric field path 40, and the apparent viscosity of the processing fluid 200 increases locally, so that the magnetic clusters are pressed with even stronger force against the workpiece 100. The reason why agglomerates of abrasive grains are formed is that the non-magnetic and non-conductive abrasive grains are affected by the dielectric polarization caused by the electric field, causing a bias in the electric charge on a particle-by-particle basis, and as a result, adjacent particles tend to aggregate together to cancel out this biased electric charge.

[0067] Then, by rotating the main magnetic body 20 and the sub magnetic body 30 together with the shaft body 10 in the above-mentioned state, the machining surface of the workpiece 100 facing the area formed by both magnetic bodies on the side surface of the shaft body 10 is polished by the abrasive grains in the magnetic clusters. At this time, the magnetic clusters are distributed along the axial direction, and the abrasive grains can be widely arranged and applied on the surface of the workpiece 100, thereby further improving the polishing efficiency as a fluid polishing.

[0068] Furthermore, in the above embodiment, if each magnetic body is configured to function as an electrode in the electric field path 40, an electric field can be generated between the main magnetic body 20 and the sub magnetic body 30. As a result, a pair of electrodes is integrated with the fluid polishing apparatus 1, which makes it possible to reduce the effort of providing the other electrode 43 at a distance from the main magnetic body 20, for example, by providing the other electrode on the workpiece each time polishing is performed.

[0069] Furthermore, in the above embodiment, if the main magnetic body 20 is a magnet magnetized in the axial direction, the magnetic clusters can be distributed in the main magnetic body 20 and the sub-magnetic body 30 in the direction in which the axis extends.

[0070] On the other hand, in the above embodiment, if the main magnetic body 20 is a magnet magnetized in the inward and outward directions, the magnetic clusters can be distributed in the axial direction along the magnetic field lines extending from one side to the other on the side surfaces of the main magnetic body 20 and the sub-magnetic body 30.

[0071] Furthermore, in the above embodiment, if the main magnetic body 20 and the sub magnetic body 30 are magnets magnetized in the axial direction with opposite magnetic pole arrangements, then the two magnetic bodies are arranged on the side of the shaft body 10 with the same magnetic poles facing each other in the axial direction, and independent magnetic field line loops are formed in the inward and outward directions, so that magnetic clusters can be distributed widely in the axial direction along these magnetic field lines.

[0072] On the other hand, if the main magnetic body 20 and the sub magnetic body 30 are magnets magnetized inward and outward directions and with opposite magnetic pole arrangements, the opposite magnetic poles will be arranged with a gap in the axial direction on the side of the shaft body 10, and magnetic clusters can be distributed widely in the axial direction along the magnetic field lines extending from one side to the other.

[0073] Furthermore, in the above embodiment, if the sub-magnetic body 30 is a magnet that is magnetized in a direction that intersects the magnetization direction of the main magnetic body 20 and so that the area facing the main magnetic body 20 on the side of the shaft body 10 has the opposite magnetic pole to the main magnetic body 20, then both magnetic bodies are arranged on the side of the shaft body 10 with the same magnetic poles facing each other in the axial direction, and independent axial magnetic field line loops are formed, so that magnetic clusters can be distributed widely in the axial direction along these magnetic field lines.

[0074] In addition, in the above embodiment, an electric field suitable for forming magnetic clusters in which abrasive grains are concentrated on the surface side of the workpiece 100 can be generated via the electric field path 40 without current flow between the electrodes due to dielectric breakdown. [Explanation of symbols]

[0075] 1...fluid polishing device, 10...shaft body, 11...insulating material, 13...cylindrical body, 15...conductive material, 20...main magnetic body, 21...conductive layer, 30...sub-magnetic body, 31...conductive layer, 40...electric field path, 41...electrode, 43...electrode, 50...rotary drive unit, 60...control unit, 70...power supply unit, 100...workpiece, 200...processing fluid.

Claims

1. A shaft body that is rotatable around an axis extending in a predetermined direction; A main magnetic body is provided in such a manner that a conductive layer is formed on a part or the whole of a cylindrical magnet surrounding the axis and that the main magnetic body is rotatable in accordance with the shaft body; a sub-magnetic body that is a cylindrical magnetic body that surrounds the axis and is disposed at an interval from the main magnetic body in the extension direction of the shaft body and is rotatable in accordance with the shaft body; one of a pair of electrodes is connected to the conductive layer of the main magnetic body, while the other electrode is provided at a position spaced a predetermined distance from the main magnetic body, and an electric field path serves as a current path for generating an electric field associated with current flow between the electrodes; the sub-magnetic body is formed with an outer diameter that is the same as or close to the outer diameter of the main magnetic body and less than a predetermined threshold value; A processing fluid containing non-magnetic and non-conductive abrasive grains is interposed between an area formed by the main magnetic body and the sub-magnetic body on the side of the shaft body and a surface to be processed of the workpiece disposed opposite to this area, and the shaft body is rotated under a magnetic field generated by the main magnetic body and an electric field generated by the electric field path, thereby realizing magnetic fluid polishing of the workpiece. Fluid polishing equipment.

2. The main magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in the axial direction, which is the direction in which the axis extends. The fluid polishing apparatus according to claim 1 .

3. The main magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in an inward and outward direction, which is a direction intersecting the axis. The fluid polishing apparatus according to claim 1 .

4. The sub-magnetic body is a magnet obtained by magnetizing a cylindrical magnetic body in the same direction as the main magnetic body but with the magnetic poles arranged in the opposite direction.

4. The fluid polishing apparatus according to claim 2.

5. The sub-magnetic body is a magnet formed by magnetizing a cylindrical magnetic body in a direction intersecting the magnetization direction of the main magnetic body and such that an area facing the main magnetic body on the side surface of the shaft body has the same magnetic pole as the main magnetic body.

4. The fluid polishing apparatus according to claim 2.

6. The sub-magnetic body is a cylindrical magnetic body having a conductive layer formed thereon in part or in whole, and is electrically insulated from the main magnetic body. The electric field path is such that the other electrode is connected to the conductive layer of the sub-magnetic body. The fluid polishing apparatus according to claim 1 .

7. A power supply unit that applies a voltage to the electric field path, The power supply unit generates an electric field strength of 2.0 kV / mm or less between the electrodes in the electric field path by applying a voltage to the electric field path.

7. The fluid polishing apparatus according to claim 1.

8. A shaft body that is rotatable around an axis extending in a predetermined direction; A main magnetic body is provided in such a manner that a conductive layer is formed on a part or the whole of a cylindrical magnet surrounding the axis and that the main magnetic body is rotatable in accordance with the shaft body; a sub-magnetic body that is a cylindrical magnetic body that surrounds the axis and is disposed at an interval from the main magnetic body in the extension direction of the shaft body and is rotatable in accordance with the shaft body; one of a pair of electrodes is connected to the conductive layer of the main magnetic body, while the other electrode is provided at a position spaced a predetermined distance from the main magnetic body, and an electric field path serves as a current path for generating an electric field associated with current flow between the electrodes; A processing fluid containing non-magnetic and non-conductive abrasive grains is interposed between an area formed by the main magnetic body and the sub-magnetic body on the side of the shaft body and a surface to be processed of the workpiece disposed opposite to this area, and the shaft body is rotated under a magnetic field generated by the main magnetic body and an electric field generated by the electric field path, thereby realizing magnetic fluid polishing of the workpiece. Fluid polishing method.

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