JP2015230734A - Method for processing glass substrate for magnetic recording medium, method for manufacturing glass substrate for magnetic recording medium, and device for processing glass substrate for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing a glass substrate for a magnetic recording medium capable of improving processing accuracy.SOLUTION: A method for processing a glass substrate for a magnetic recording medium includes a chamfering process of chamfering the end surface of a glass substrate for a magnetic recording medium. The chamfering process includes: a first grinding process of rotating the glass substrate by sandwiching it between a first rotary member for supporting a first main surface of the glass substrate and a second rotary member for supporting a second main surface of the glass substrate, and grinding the end surface of the glass substrate with a first chamfering grindstone; and a second grinding process of rotating the glass substrate by supporting it by either the first rotary member or the second rotary member after the first grinding process, and grinding the end surface of the glass substrate by a second chamfering grindstone the average grain diameter of whose abrasive grains is smaller than that of the first chamfering grindstone. In the second grinding process, the holding force of the glass substrate by the first rotary member and the second rotary member is smaller than that in the first grinding process.

Description

  The present invention relates to a method for processing a glass substrate for a magnetic recording medium, a method for manufacturing a glass substrate for a magnetic recording medium, and a processing apparatus for a glass substrate for a magnetic recording medium.

  The manufacturing method of the glass substrate for magnetic recording media has a chamfering process which chamfers the end surface of a glass substrate. In the chamfering step, the glass substrate is sandwiched between the rotation holding table and the work clamper and is ground while rotating (for example, see Patent Document 1).

JP 2012-143852 A

  Conventionally, because of the positional error between the rotation center of the rotation holding table and the rotation center of the work clamper, the rotation of the glass substrate is unstable, and the processing accuracy of the glass substrate is low.

  The present invention has been made in view of the above problems, and mainly aims to provide a method for processing a glass substrate for a magnetic recording medium, which can improve processing accuracy.

In order to solve the above problems, according to one aspect of the present invention,
A chamfering step for chamfering the end face of the glass substrate for the magnetic recording medium;
The chamfering process is
The first rotating member that supports the first main surface of the glass substrate and the second rotating member that supports the second main surface of the glass substrate are rotated while sandwiching the glass substrate, and the end surface of the glass substrate A first grinding step of grinding with a first chamfering grindstone,
After the first grinding step, the glass substrate is supported and rotated by at least one of the first rotating member and the second rotating member, and the average grain size of the abrasive grains is smaller than that of the first chamfering grindstone. A second grinding step of grinding the end face of the glass substrate with a second chamfering grindstone,
In the second grinding step, there is provided a method for processing a glass substrate for a magnetic recording medium, wherein the holding force of the glass substrate by the first rotating member and the second rotating member is smaller than in the first grinding step. The

  According to one embodiment of the present invention, a method for processing a glass substrate for a magnetic recording medium that can improve processing accuracy is provided.

It is a flowchart which shows the manufacturing method of the glass substrate for magnetic recording media by 1st Embodiment. It is a fragmentary sectional view which shows the state at the time of the 1st grinding process of the processing apparatus of the glass substrate for magnetic recording media by 1st Embodiment. It is a fragmentary sectional view which shows the state at the time of the 2nd grinding process of the processing apparatus of the glass substrate for magnetic recording media by 1st Embodiment. It is sectional drawing which shows the principal part of the processing apparatus of the glass substrate for magnetic recording media by the modification of 1st Embodiment. It is sectional drawing which shows the principal part of the processing apparatus of the glass substrate for magnetic recording media by 2nd Embodiment. It is sectional drawing which shows the principal part of the processing apparatus of the glass substrate for magnetic recording media by the modification of 2nd Embodiment. It is sectional drawing which shows the principal part of the processing apparatus of the glass substrate for magnetic recording media by another modification of 2nd Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted. In this specification, “to” representing a numerical range means a range including numerical values before and after the numerical range.

[First Embodiment]
FIG. 1 is a flowchart showing a method for manufacturing a glass substrate for a magnetic recording medium according to the first embodiment. A glass substrate for a magnetic recording medium is disk-shaped and has a circular hole in the center. A magnetic recording medium can be obtained by forming a magnetic layer or the like on a glass substrate for a magnetic recording medium.

  As shown in FIG. 1, the method for manufacturing a glass substrate for a magnetic recording medium includes a base plate processing step S11, a chamfering step S12, an end surface polishing step S14, a main surface polishing step S15, and the like. An etching process, a cleaning process, a drying process, etc. may be performed between these processes or after these processes.

  In the base plate processing step S11, a disk-shaped glass substrate having a circular hole in the center is obtained by processing the glass base plate. The glass base plate is formed by, for example, a float method, a fusion method, a press forming method, a down draw method, a redraw method, or the like.

  The chamfering step S12 forms a chamfered portion and a side surface portion on the end surface of the glass substrate by grinding the end surfaces (the inner peripheral end surface and the outer peripheral end surface) of the glass substrate with a chamfering grindstone. The chamfered portion may be inclined with respect to the main surface of the glass substrate, and the side surface portion may be perpendicular to the main surface of the glass substrate. Note that the chamfered portion may not be a flat surface, and may be a rounded curved surface.

  The end surface polishing step S14 removes the work-affected layer in the chamfered portion and the side surface portion by polishing the chamfered portion and the side surface portion with a rotating brush while supplying the polishing liquid. A polishing liquid is supplied to the polishing portion by the rotating brush.

  Note that a plurality of end surface polishing steps may be sequentially performed, and the work-affected layer may not be removed with a rotating brush alone. In addition to brush polishing with a rotating brush, sponge polishing, viscous fluid polishing, magnetic fluid polishing, and the like may be performed. A cleaning process and a drying process may be performed between the plurality of end face polishing processes.

  The main surface polishing step S15 polishes the main surface (first main surface and second main surface) of the glass substrate. In the main surface polishing step, a double-side polishing machine that simultaneously polishes the first main surface and the second main surface of the glass substrate may be used. The double-side polishing machine may polish a plurality of glass substrates simultaneously.

  A plurality of main surface polishing steps may be performed sequentially. The plurality of main surface polishing steps are performed by changing the type of polishing pad and the average particle size of the abrasive grains contained in the polishing liquid. A cleaning process and a drying process may be performed between the plurality of main surface polishing processes.

  In addition, the order of each process shown in FIG. 1 is not specifically limited. For example, the end surface polishing step S14 may be performed after the main surface polishing step S15. Moreover, processes other than the process shown in FIG. 1 may be performed. For example, before the main surface polishing step S15, wrapping of the main surface of the glass substrate (for example, loose abrasive wrap, fixed abrasive wrap, etc.) may be performed. Further, chemical strengthening may be performed between the main surface polishing step S15 after the end surface polishing step S14 and the main surface polishing step S15. Chemical strengthening replaces ions with a small ion radius (for example, Li ions and Na ions) contained on the surface of a glass plate with ions with a large ion radius (for example, K ions) to form a strengthened layer with a predetermined depth from the surface To do. Since the compressive stress remains in the reinforcing layer, it is difficult to be damaged.

  Next, the chamfering process will be described with reference to FIGS. The chamfering process includes a first grinding process and a second grinding process. In the chamfering process, the processing apparatus shown in FIGS. 2 and 3 is used.

  FIG. 2 is a partial cross-sectional view showing a state during the first grinding process of the glass substrate processing apparatus for a magnetic recording medium according to the first embodiment. FIG. 3 is a partial cross-sectional view showing a state in the second grinding step of the glass substrate processing apparatus for a magnetic recording medium according to the first embodiment.

  The glass substrate processing apparatus chamfers the inner peripheral end surface and the outer peripheral end surface of the glass substrate 10 for a magnetic recording medium. The glass substrate processing apparatus includes an inner peripheral chamfering grindstone 20, an outer peripheral chamfering grindstone 30, a lower rotating member 40, an upper rotating member 50, and a rotary motor 60 as a first drive source, as shown in FIGS. , A lower support member 70, an upper support member 80, and a cylinder 90 as a second drive source.

  The inner peripheral chamfering grindstone 20 is movable in the horizontal direction and the vertical direction. The inner peripheral chamfering grindstone 20 grinds the inner peripheral end face of the glass substrate 10 while rotating around the center line of the inner peripheral chamfering grindstone 20. The center line of the inner peripheral chamfering grindstone 20 and the center line of the glass substrate 10 are parallel.

  The inner peripheral chamfering grindstone 20 may include a plurality of abrasive grains and a metal that bonds the plurality of abrasive grains. As the abrasive grains, diamond abrasive grains, cubic boron nitride (CBN) abrasive grains, alumina abrasive grains, silicon carbide abrasive grains and the like are used. The inner peripheral chamfering grindstone 20 may be an electrodeposition grindstone that fixes abrasive grains by plating. The inner peripheral chamfering grindstone 20 may be a metal bond grindstone formed by sintering abrasive grains, metal powder, or the like.

  The inner peripheral chamfering grindstone 20 includes a first inner peripheral chamfering grindstone part 21 and a second inner peripheral chamfering grindstone part 22. The average particle size of the abrasive grains of the second inner peripheral chamfering grindstone portion 22 is smaller than the average particle size of the abrasive grains of the first inner peripheral chamfering grindstone portion 21. The inner peripheral chamfering grindstone 20 may further include a third inner peripheral chamfering grindstone part, and the number of inner peripheral chamfering grindstone parts is not limited.

  The average particle diameter of the abrasive grains of the first inner peripheral chamfering grindstone portion 21 is, for example, 30 to 60 μm, preferably 30 to 50 μm. Moreover, the average particle diameter of the abrasive grains of the second inner peripheral chamfering grindstone portion 22 is, for example, 15 to 40 μm, preferably 15 to 30 μm. The average particle diameter of the abrasive grains is a median diameter (also referred to as D50) and can be measured by a laser diffraction scattering method.

  The first inner peripheral chamfering grindstone portion 21 and the second inner peripheral chamfering grindstone portion 22 have a plurality of annular grinding grooves on the outer periphery thereof, and the inner periphery of the glass substrate 10 on the wall surface of one of the grinding grooves. Grind the end face. The cross-sectional shape of the grinding groove may be an isosceles trapezoid.

  The outer peripheral chamfering grindstone 30 is movable in the horizontal direction and the vertical direction. The outer peripheral chamfering grindstone 30 grinds the outer peripheral end surface of the glass substrate 10 while rotating around the center line of the outer peripheral chamfering grindstone 30. The center line of the outer peripheral chamfering grindstone 30 and the center line of the glass substrate 10 are parallel.

  The outer peripheral chamfering grindstone 30 may include a plurality of abrasive grains and a metal that combines the plurality of abrasive grains. As the abrasive grains, diamond abrasive grains, cubic boron nitride (CBN) abrasive grains, alumina abrasive grains, silicon carbide abrasive grains and the like are used. The outer peripheral chamfering grindstone 30 may be an electrodeposited grindstone that fixes abrasive grains by plating. The outer peripheral chamfering grindstone 30 may be a metal bond grindstone formed by sintering abrasive grains, metal powder, or the like.

  The outer peripheral chamfering grindstone 30 includes a first outer peripheral chamfering grindstone portion 31 and a second outer peripheral chamfering grindstone portion 32. The average particle size of the abrasive grains of the second outer peripheral chamfering grindstone portion 32 is smaller than the average particle size of the abrasive grains of the first outer peripheral chamfering grindstone portion 31. The outer peripheral chamfering grindstone 30 may further include a third outer peripheral chamfering grindstone part, and the number of outer peripheral chamfering grindstone parts is not limited.

  The average particle diameter of the abrasive grains of the first outer peripheral chamfering grindstone portion 31 is, for example, 30 to 60 μm, preferably 30 to 50 μm. Moreover, the average particle diameter of the abrasive grains of the second outer peripheral chamfering grindstone 32 is, for example, 15 to 40 μm, preferably 15 to 30 μm. The average particle diameter of the abrasive grains is a median diameter (also referred to as D50) and can be measured by a laser diffraction scattering method.

  The first outer peripheral chamfering grindstone portion 31 and the second outer peripheral chamfering grindstone portion 32 have a plurality of annular grinding grooves on the outer periphery thereof, and the outer peripheral end surface of the glass substrate 10 is ground by the wall surface of any of the grinding grooves. To do. The cross-sectional shape of the grinding groove may be an isosceles trapezoid.

  The lower rotating member 40 supports the lower surface of the glass substrate 10. The lower rotating member 40 vacuum-sucks the lower surface of the glass substrate 10 and rotates together with the glass substrate 10. The lower rotating member 40 includes a lower table portion 41 that supports the lower surface of the glass substrate 10 and a lower rotating shaft portion 42 that is fixed to the lower table portion 41.

  Note that the method of fixing the glass substrate 10 to the lower rotating member 40 is not limited to vacuum suction, and may be, for example, adhesive fixing or freeze fixing.

  The upper rotating member 50 supports the upper surface of the glass substrate 10. The upper rotating member 50 is pressed against the upper surface of the glass substrate 10 and rotates together with the glass substrate 10. The upper rotating member 50 includes an upper table portion 51 that supports the upper surface of the glass substrate 10, and an upper rotating shaft portion 52 that is fixed to the upper table portion 51.

  A through hole 56 parallel to the vertical direction is formed in the upper rotating member 50. The inner peripheral chamfering grindstone 20 or the rotating shaft portion 23 that rotates together with the inner peripheral chamfering grindstone 20 is inserted into the through hole 56.

  The rotation motor 60 rotates the lower rotation member 40 around the lower rotation shaft portion 42. The rotation motor 60 is fixed to the frame Fr, and is connected to the lower rotation shaft portion 42 via a belt, a pulley, or the like. The rotary motor 60 may be connected coaxially with the lower rotary shaft portion 42.

  The lower support member 70 holds a bearing (not shown) that rotatably supports the lower rotation shaft portion 42 of the lower rotation member 40. The lower support member 70 is fixed to the frame Fr.

  The upper support member 80 holds a bearing 57 that rotatably supports the upper rotation shaft portion 52 of the upper rotation member 50. The upper support member 80 is fixed to an upper elevating member 91 that is movable up and down with respect to the frame Fr, and is moved up and down together with the upper elevating member 91. As the upper support member 80 moves up and down, the upper rotating member 50 is raised and lowered.

  The cylinder 90 may be either a fluid pressure cylinder such as a hydraulic cylinder or a gas pressure cylinder, or an electric cylinder. The cylinder 90 raises and lowers the upper rotation member 50 relative to the lower rotation member 40 by raising and lowering the upper support member 80 relative to the lower support member 70.

  One end of the cylinder 90 is fixed to the frame Fr, and the other end of the cylinder 90 is fixed to a lower elevating member 92 that can move up and down with respect to the frame Fr. The lower lifting member 92 and the upper lifting member 91 are connected by a plurality of rods 93.

  When the upper support member 80 is lowered by driving the cylinder 90, the upper rotation member 50 is lowered and comes into contact with the glass substrate 10 supported by the lower rotation member 40. Thus, the lower rotating member 40 and the upper rotating member 50 sandwich the glass substrate 10. A clamping force corresponding to the driving force of the cylinder 90 is generated. On the other hand, when the upper support member 80 is raised by driving the cylinder 90, the upper rotation member 50 is raised and separated from the glass substrate 10 supported by the lower rotation member 40.

  In addition, although the cylinder 90 of this embodiment raises / lowers the upper support member 80 and the upper rotation member 50, you may raise / lower the lower support member 70 and the lower rotation member 40. The cylinder 90 only needs to move the upper rotation member 50 relative to the lower rotation member 40 by moving the upper support member 80 relative to the lower support member 70.

  Next, a chamfering process using the processing apparatus having the above configuration will be described. The chamfering process includes a first grinding process and a second grinding process.

  In the first grinding step, as shown in FIG. 2, the glass substrate 10 is rotated between the lower rotating member 40 and the upper rotating member 50, and the inner peripheral end surface of the glass substrate 10 is rotated to the first inner peripheral chamfering stone portion 21. And the outer peripheral end face of the glass substrate 10 is ground by the first outer peripheral chamfering grindstone 31.

  In the first grinding step, the feed speeds of the first inner peripheral chamfering grindstone portion 21 and the first outer peripheral chamfering grindstone portion 31 to the radially inner side of the glass substrate 10 are, for example, 0.5 to 10.0 mm, respectively. / Min, preferably 0.8 to 5.0 mm / min.

  In the first grinding step, the radial cut amount of the inner peripheral end face of the glass substrate 10 and the radial cut amount of the outer peripheral end face of the glass substrate 10 are each 0.3 to 1 mm, for example.

  In the second grinding step, the glass substrate 10 is supported and rotated by the lower rotating member 40 as shown in FIG. 3, the outer peripheral end surface of the glass substrate 10 is ground by the second outer peripheral chamfering grindstone 32, and the glass The inner peripheral end face of the substrate 10 is ground by the second inner peripheral chamfering grindstone 22.

  In the second grinding step, the glass substrate 10 may be supported and rotated at least one of the lower rotating member 40 and the upper rotating member 50.

  In the second grinding step, the feed speeds of the first inner peripheral chamfering grindstone portion 21 and the first outer peripheral chamfering grindstone portion 31 to the inner side in the radial direction of the glass substrate 10 are, for example, 0.1 to 2.0 mm, respectively. / Min, preferably 0.3 to 1.0 mm / min.

  In the second grinding step, the radial cut amount of the inner peripheral end surface of the glass substrate 10 and the radial cut amount of the outer peripheral end surface of the glass substrate 10 are each 0.1 to 0.2 mm, for example.

  By the way, in the 1st grinding process, the grindstone with a larger average grain size of an abrasive grain is used than the 2nd grinding process, and the grinding load of glass substrate 10 is large. The lower rotating member 40 and the upper rotating member 50 are fixed with the glass substrate 10 sandwiched therebetween so that the positional displacement of the glass substrate 10 does not occur due to the grinding load.

  In the first grinding step, the clamping force of the glass substrate 10 is set according to the diameter of the glass substrate 10. When the diameter of the glass substrate 10 is 2.5 inches, the clamping force of the glass substrate 10 in the first grinding step is, for example, 600 to 1200 N, preferably 600 to 800 N. In the first grinding step, when the clamping force of the glass substrate 10 is 600 N or more, it is possible to prevent the positional deviation of the glass substrate 10 due to the grinding load. Moreover, the damage of the glass substrate 10 by clamping force can be suppressed as the clamping force of the glass substrate 10 is 1200 N or less.

  On the other hand, in the second grinding step, a grindstone having a smaller average grain size of abrasive grains is used than in the first grinding step, and the grinding load on the glass substrate 10 is small. Therefore, in the second grinding process, the driving force of the cylinder 90 is set smaller than in the first grinding process, and the clamping force of the glass substrate 10 is set smaller. The sandwiching force of the glass substrate 10 in the second grinding step is 80% or less, preferably 50% or less, more preferably zero of the sandwiching force of the glass substrate 10 in the first grinding step. When the clamping force of the glass substrate 10 is zero, the upper rotating member 50 may be separated from the glass substrate 10 supported by the lower rotating member 40 as shown in FIG. In the second grinding step, the holding force of the glass substrate 10 is set so that the position shift of the glass substrate 10 due to the grinding load can be prevented.

  As described above, according to the present embodiment, the clamping force of the glass substrate 10 is smaller in the second grinding process than in the first grinding process. Therefore, the horizontal position of the upper rotating member 50 with respect to the lower rotating member 40 is not completely constrained, and the influence of the position error between the rotating center of the lower rotating member 40 and the rotating center of the upper rotating member 50 is small. 10 is stabilized, and the processing accuracy (for example, concentricity, roundness, etc.) of the glass substrate 10 is improved.

  In the 2nd grinding process, the adsorption power of glass substrate 10 by lower rotating member 40 may be larger than the 1st grinding process. Since the adsorption force increases, the holding force of the glass substrate 10 can be further reduced.

  In the present embodiment, the lower surface of the glass substrate 10 is the first main surface of the glass substrate 10, the upper surface of the glass substrate 10 is the second main surface of the glass substrate 10, and the lower rotating member 40 is the first rotating member. The upper rotating member 50 corresponds to the second rotating member, the lower supporting member 70 corresponds to the first supporting member, and the upper supporting member 80 corresponds to the second supporting member. However, in this specification, terms such as “first” and “second” do not limit the vertical relationship. For example, the lower rotating member 40 may correspond to the second rotating member, and the upper rotating member 50 may correspond to the first rotating member.

[Modification of First Embodiment]
FIG. 4 is a cross-sectional view showing a main part of a glass substrate processing apparatus for a magnetic recording medium according to a modification of the first embodiment. The upper rotating member 50 shown in FIG. 4 has a spiral slit 58 in the upper rotating shaft portion 52. Accordingly, the upper rotating shaft portion 52 can be bent and deformed, and the influence of the position error between the rotation center of the lower rotation member 40 and the rotation center of the upper rotation member 50 can be reduced.

  The slit 58 may be formed in either the upper rotating shaft part 52 or the upper table part 51, or may be formed in both. Moreover, the slit 58 may be formed in any of the upper rotating member 50 and the lower rotating member 40, and may be formed in both.

[Second Embodiment]
FIG. 5 is a cross-sectional view showing a main part of a processing apparatus for a glass substrate for a magnetic recording medium according to the second embodiment. The difference between the present embodiment and the first embodiment will be mainly described below with reference to FIG.

  The upper rotating member 50 </ b> A supports the upper surface of the glass substrate 10. The upper rotating member 50 </ b> A is pressed against the upper surface of the glass substrate 10 fixed to the lower rotating member 40, and is rotated with the rotation of the lower rotating member 40.

  The upper rotating member 50A includes an upper table portion 51A that supports the upper surface of the glass substrate 10, a shaft portion 52A that is fixed to the upper table portion 51A, and a ring portion 53A that protrudes from the outer peripheral surface of the shaft portion 52A.

  The upper support member 80A rotatably supports the upper rotation member 50A. Further, the upper support member 80A supports the upper rotation member 50A so as to be movable in a direction perpendicular to the lower rotation shaft portion 42 (horizontally movable in FIG. 5).

  The upper support member 80A includes a cylindrical portion 82A into which the shaft portion 52A is inserted, and a concave portion 83A formed on the inner peripheral surface of the cylindrical portion 82A. The ring portion 53A is inserted into the recess 83A.

  The upper support member 80A contacts and supports the upper rotation member 50A via a ball 86A that is movable in a direction perpendicular to the lower rotation shaft portion. The balls 86A are disposed on both upper and lower sides of the ring portion 53A, and restrict the raising and lowering of the upper rotating member 50A with respect to the upper supporting member 80A. A plurality of balls 86A may be arranged on both the upper and lower sides of the ring portion 53A. The plurality of balls 86A may be held by a ball retainer (not shown).

  In addition, arrangement | positioning of a ring part and a recessed part may be reverse. That is, the ring portion may protrude from the inner peripheral surface of the cylindrical portion 82A, and the concave portion may be formed on the outer peripheral surface of the shaft portion 52A.

  By the way, according to the present embodiment, the upper support member 80A supports the upper rotation member 50A so as to be movable in a direction perpendicular to the lower rotation shaft portion 42 (horizontally movable in FIG. 5). The upper support member 80A does not determine the rotation center of the upper rotation member 50A, and the lower rotation shaft portion 42 can be used as a common rotation shaft portion for the lower rotation member 40 and the upper rotation member 50A. Therefore, the rotation of the glass substrate 10 is stabilized, and the processing accuracy (for example, concentricity, roundness, etc.) of the glass substrate 10 is improved.

  Further, according to the present embodiment, since the lower rotating shaft portion 42 can be used as a common rotating shaft portion for the lower rotating member 40 and the upper rotating member 50A, unlike the first embodiment, the first rotating shaft portion shown in FIG. It is not necessary to adjust the clamping force of the glass substrate 10 in the first grinding step and the second grinding step shown in FIG.

[Modification of Second Embodiment]
FIG. 6 is a cross-sectional view showing a main part of a processing apparatus for a glass substrate for a magnetic recording medium according to a modification of the second embodiment. In this modification, a magnetic repulsive force is used instead of the ball 86A.

  The upper rotating member 50 </ b> B supports the upper surface of the glass substrate 10. The upper rotating member 50 </ b> B is pressed against the upper surface of the glass substrate 10 fixed to the lower rotating member 40, and is rotated with the rotation of the lower rotating member 40.

  The upper rotating member 50B includes an upper table portion 51B that supports the upper surface of the glass substrate 10, a shaft portion 52B that is fixed to the upper table portion 51B, a ring portion 53B that protrudes from the outer peripheral surface of the shaft portion 52B, and a ring portion 53B. And a magnet portion 54B fixed to the upper and lower surfaces. The magnet portion 54B may be a permanent magnet or an electromagnet.

  The upper support member 80B rotatably supports the upper rotation member 50B. Further, the upper support member 80B supports the upper rotation member 50B so as to be movable in a direction perpendicular to the lower rotation shaft portion 42 (horizontally movable in FIG. 6).

  The upper support member 80B includes a cylindrical portion 82B into which the shaft portion 52B is inserted, a concave portion 83B formed on the inner peripheral surface of the cylindrical portion 82B, and a magnet portion 84B fixed to the upper and lower surfaces of the concave portion 83B. . The magnet portion 84B may be a permanent magnet or an electromagnet. The ring portion 53B is inserted into the recess 83B, and the magnet portion 54B and the magnet portion 84B are disposed to face each other. The magnet part 54B and the magnet part 84B generate a magnetic repulsive force.

  The upper support member 80B supports the upper rotation member 50B in a non-contact manner by a magnetic repulsive force acting between the upper support member 80B and the upper rotation member 50B. The magnet units composed of the magnet part 54B and the magnet part 84B are arranged in the vertical direction, and restrict the raising and lowering of the upper rotating member 50A with respect to the upper support member 80A.

  In addition, arrangement | positioning of a ring part and a recessed part may be reverse. That is, the ring portion may protrude from the inner peripheral surface of the cylindrical portion 82B, and the concave portion may be formed on the outer peripheral surface of the shaft portion 52B.

  By the way, according to the present modification, the upper support member 80B supports the upper rotation member 50B so as to be movable in the direction perpendicular to the lower rotation shaft portion 42 (in FIG. 6, it can be moved horizontally). The upper support member 80B does not determine the rotation center of the upper rotation member 50B, and the lower rotation shaft portion 42 can be used as a common rotation shaft portion for the lower rotation member 40 and the upper rotation member 50B. Therefore, the rotation of the glass substrate 10 is stabilized, and the processing accuracy (for example, concentricity, roundness, etc.) of the glass substrate 10 is improved.

  Further, according to the present modification, the lower rotating shaft portion 42 can be used as a common rotating shaft portion for the lower rotating member 40 and the upper rotating member 50B. Therefore, unlike the first embodiment, the first rotating shaft portion shown in FIG. It is not necessary to adjust the clamping force of the glass substrate 10 in the first grinding step and the second grinding step shown in FIG.

  Furthermore, according to this modification, the upper support member 80B supports the upper rotation member 50B in a non-contact manner by a magnetic repulsive force. Therefore, the rotational resistance of the upper rotating member 50B is small.

[Another Modification of Second Embodiment]
FIG. 7 is a cross-sectional view showing a main part of a processing apparatus for a glass substrate for a magnetic recording medium according to another modification of the second embodiment. In this modification, the pressure of a gas such as air is used instead of the ball 86A.

  The upper rotating member 50 </ b> C supports the upper surface of the glass substrate 10. The upper rotating member 50 </ b> C is pressed against the upper surface of the glass substrate 10 fixed to the lower rotating member 40, and is rotated with the rotation of the lower rotating member 40.

  The upper rotating member 50C includes an upper table portion 51C that supports the upper surface of the glass substrate 10, a shaft portion 52C that is fixed to the upper table portion 51C, and a ring portion 53C that protrudes from the outer peripheral surface of the shaft portion 52C.

  The upper support member 80C rotatably supports the upper rotation member 50C. The upper support member 80C supports the upper rotation member 50C so as to be movable in a direction perpendicular to the lower rotation shaft portion 42 (in FIG. 7, it can be moved horizontally).

  The upper support member 80C includes a cylindrical portion 82C into which the shaft portion 52C is inserted, a recess 83C formed on the inner peripheral surface of the cylindrical portion 82C, and a gas hole 85C formed on the upper and lower surfaces of the recess 83C. . The ring portion 53C is inserted into the recess 83C, and gas is blown from the gas hole 85C toward the ring portion 53C.

  For example, the upper support member 80C supports the upper rotation member 50C in a non-contact manner by the pressure of a gas flowing between the upper support member 80C and the upper rotation member 50C. The gas hole 85C blows gas from the upper and lower sides to the ring portion 53C and restricts the raising and lowering of the upper rotating member 50C with respect to the upper supporting member 80C.

  In addition, arrangement | positioning of a ring part and a recessed part may be reverse. That is, the ring portion may protrude from the inner peripheral surface of the cylindrical portion 82C, and the concave portion may be formed on the outer peripheral surface of the shaft portion 52C. Further, the gas hole 85C may be formed not on the upper and lower surfaces of the concave portion but on the upper and lower surfaces of the ring portion, but may be formed on a member fixed to the frame Fr. Gas piping is easy.

  By the way, according to the present modification, the upper support member 80C supports the upper rotation member 50C so as to be movable in a direction perpendicular to the lower rotation shaft portion 42 (in FIG. 7, it can be moved horizontally). The upper support member 80C does not determine the rotation center of the upper rotation member 50C, and the lower rotation shaft portion 42 can be used as a common rotation shaft portion for the lower rotation member 40 and the upper rotation member 50C. Therefore, the rotation of the glass substrate 10 is stabilized, and the processing accuracy (for example, concentricity, roundness, etc.) of the glass substrate 10 is improved.

  In addition, according to the present modification, the lower rotating shaft portion 42 can be used as a common rotating shaft portion for the lower rotating member 40 and the upper rotating member 50C. Therefore, unlike the first embodiment, the first rotating shaft portion shown in FIG. It is not necessary to adjust the clamping force of the glass substrate 10 in the first grinding step and the second grinding step shown in FIG.

  Furthermore, according to this modification, the upper support member 80C supports the upper rotation member 50C in a non-contact manner by the pressure of the gas. Therefore, the rotational resistance of the upper rotating member 50C is small.

  The upper support member may support the upper rotation member by both the gas pressure and the magnetic repulsion force.

  The embodiments of the glass substrate processing method for the magnetic recording medium, the method for manufacturing the glass substrate for the magnetic recording medium, the processing apparatus for the glass substrate for the magnetic recording medium, and the like have been described above. However, various modifications and improvements are possible within the scope of the gist of the present invention described in the claims.

  For example, in the above-described embodiment and the like, in the first grinding step, the inner peripheral end surface of the glass substrate 10 and the outer peripheral end surface of the glass substrate 10 are ground simultaneously, but may be ground separately. The same applies to the second grinding step.

Fr processing apparatus frame 10 glass substrate 20 inner circumferential chamfering grindstone 21 first inner circumferential chamfering grindstone 22 second inner circumferential chamfering grindstone 23 rotating shaft 30 of inner circumferential chamfering grindstone 31 outer circumferential chamfering grindstone 31 first Outer peripheral chamfering grindstone portion 32 Second outer peripheral chamfering grindstone portion 40 Lower rotating member 41 Lower table portion 42 Lower rotating shaft portion 50 Upper rotating member 51 Upper table portion 52 Upper rotating shaft portion 57 Bearing 58 Slit 60 Rotating motor 70 Lower support member 80 Upper support member 86A Ball 90 Cylinder 91 Upper elevating member 92 Lower elevating member

Claims (15)

A chamfering step for chamfering the end face of the glass substrate for the magnetic recording medium;
The chamfering process is
The first rotating member that supports the first main surface of the glass substrate and the second rotating member that supports the second main surface of the glass substrate are rotated while sandwiching the glass substrate, and the end surface of the glass substrate A first grinding step of grinding with a first chamfering grindstone,
After the first grinding step, the glass substrate is supported and rotated by at least one of the first rotating member and the second rotating member, and the average grain size of the abrasive grains is smaller than that of the first chamfering grindstone. A second grinding step of grinding the end face of the glass substrate with a second chamfering grindstone,
In the second grinding step, a glass substrate processing method for a magnetic recording medium, wherein the holding force of the glass substrate by the first rotating member and the second rotating member is smaller than in the first grinding step.   The method for processing a glass substrate for a magnetic recording medium according to claim 1, wherein the clamping force in the second grinding step is 80% or less of the clamping force in the first grinding step.   The method for processing a glass substrate for a magnetic recording medium according to claim 1, wherein the clamping force in the second grinding step is zero.   The said clamping force in a said 1st grinding process is a processing method of the glass substrate for magnetic recording media of any one of Claims 1-3 which is 600-1200N.   The method for processing a glass substrate for a magnetic recording medium according to claim 1, wherein at least one of the first rotating member and the second rotating member has a slit.   The manufacturing method of the glass substrate for magnetic recording media using the processing method of the glass substrate for magnetic recording media of any one of Claims 1-5. A chamfering step for chamfering the end face of the glass substrate for the magnetic recording medium;
The chamfering step rotates the glass substrate between the first rotating member that supports the first main surface of the glass substrate and the second rotating member that supports the second main surface of the glass substrate, A grinding step of grinding the end face of the glass substrate with a chamfering grindstone;
In the grinding step, the first rotary member is driven to rotate about the rotary shaft portion of the first rotary member, and the second rotary member is rotatable and moved in a direction perpendicular to the rotary shaft portion. A method of processing a glass substrate for a magnetic recording medium that is freely supported. A support member that rotatably supports the second rotating member is used,
The method for processing a glass substrate for a magnetic recording medium according to claim 7, wherein the support member contacts and supports the second rotation member via a ball movable in a direction perpendicular to the rotation shaft portion. A support member that rotatably supports the second rotating member is used,
The processing of the glass substrate for a magnetic recording medium according to claim 7, wherein the support member supports the second rotating member in a non-contact manner by a magnetic repulsive force acting between the supporting member and the second rotating member. Method. A support member that rotatably supports the second rotating member is used,
10. The glass substrate for a magnetic recording medium according to claim 7, wherein the support member supports the second rotation member in a non-contact manner depending on a pressure of a gas flowing between the support member and the second rotation member. Processing method.   The manufacturing method of the glass substrate for magnetic recording media using the processing method of the glass substrate for magnetic recording media of any one of Claims 7-10. An apparatus for processing a glass substrate for a magnetic recording medium, which chamfers the end surface of the glass substrate for the magnetic recording medium,
A first rotating member that supports the first main surface of the glass substrate;
A second rotating member that supports the second main surface of the glass substrate;
A first drive source for rotating the first rotating member around a rotation shaft portion of the first rotating member;
A first support member that holds a bearing that rotatably supports the rotary shaft portion of the first rotary member;
A second support member for rotatably supporting the second rotation member;
The second rotating member is moved relative to the first rotating member by moving the second supporting member relative to the first supporting member, and the first rotating member and the second rotating member are moved relative to the first rotating member. A second drive source sandwiching the glass substrate with a rotating member,
The glass substrate processing apparatus for a magnetic recording medium, wherein the second support member supports the second rotation member so as to be rotatable and movable in a direction perpendicular to the rotation shaft portion.   The processing of the glass substrate for a magnetic recording medium according to claim 12, wherein the second support member contacts and supports the second rotation member via a ball movable in a direction perpendicular to the rotation shaft portion. apparatus.   13. The magnetic recording medium for a magnetic recording medium according to claim 12, wherein the second support member supports the second rotation member in a non-contact manner by a magnetic repulsive force acting between the second support member and the second rotation member. Glass substrate processing equipment.   The magnetic recording medium according to claim 12 or 14, wherein the second support member supports the second rotation member in a non-contact manner by a pressure of a gas flowing between the second support member and the second rotation member. Glass substrate processing equipment.

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