JPWO2010140595A1 - Method for polishing plate - Google Patents

Abstract

In the polishing method for a plate-like body in which the plate-like body is polished by a rotating polishing tool while moving the plate-like body in a predetermined direction, the rotation direction of the polishing tool is reversed at a predetermined timing.

Description

  The present invention relates to a method for polishing a plate-like body, and more particularly to a method for polishing a plate-like body in which a glass substrate for an FPD (Flat Panel Display) used for a liquid crystal display or the like is polished by a polishing apparatus.

  The glass substrate for FPD used for liquid crystal displays and the like is formed by forming a molten glass into a plate shape by a glass manufacturing method called a float method, and this is performed by a continuous polishing apparatus disclosed in Patent Document 1 or the like. By polishing and removing fine irregularities and undulations on the surface, a thin plate having a thickness of about 0.4 to 1.1 mm that satisfies the flatness required for a glass substrate for a liquid crystal display is produced.

  In such a continuous polishing apparatus, as described in Patent Document 2, a glass substrate is generally polished with a polishing pad (polishing tool) that rotates and revolves.

  In a conventional continuous polishing apparatus, the glass substrate is conveyed while the surface opposite to the surface to be polished is adsorbed and held on the adsorption sheet adhered to the table, and continuously conveyed by the conveying device that conveys the table. The surface to be polished is sequentially polished by the polishing pads of a plurality of polishing machines installed above the path. The polishing pad is rotated around a predetermined rotation center by a rotation / revolution mechanism and polishes the glass substrate while being revolved around the predetermined rotation center. When a rectangular polishing pad is used, only revolving motion is performed. As a continuous polishing apparatus that uses a rectangular polishing pad, there are a continuous polishing apparatus that consists of only a rectangular polishing pad and a continuous polishing apparatus that combines a rectangular polishing pad and a circular polishing pad that rotates and revolves.

Japanese Unexamined Patent Publication No. 2007-190657 Japanese Unexamined Patent Publication No. 2001-293656

  In conventional polishing apparatuses, the polishing rate of the glass substrate decreases with the lapse of the polishing time, and if the polishing rate falls below a predetermined threshold, it is necessary to truing or dressing the polishing pad. There was a problem that could not be raised. In addition, even when there is no need for truing or dressing of the polishing tool in the conventional polishing apparatus, the polishing rate decreases with the lapse of the polishing time, so continuous polishing with a substantially constant polishing rate cannot be performed. There was also a problem that the polishing time was long.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a plate-like polishing method capable of polishing a plate-like body by controlling the polishing rate to be substantially constant.

  The present invention provides a polishing method for a plate-like body in which the plate-like body is polished by a rotating polishing tool while moving the plate-like body in a predetermined direction, wherein the rotation direction of the polishing tool is reversed at a predetermined timing. A plate-like body polishing method is provided.

  When the polishing tool is viewed macroscopically and separated into a main body (hard portion) and a fluff (soft portion), the fluff that actually polishes the plate-like body has directionality by polishing, truing, or the like. That is, the fluff has a directionality inclined from the upstream side to the downstream side in the polishing direction. If polishing is continued in such a direction, the rotational resistance of the fluff with respect to the plate-like body decreases, so that the polishing rate decreases as the polishing time elapses. Therefore, when the rotational resistance of the fluff with respect to the plate-like body becomes equal to or less than a predetermined value, that is, when polishing with the fluff cannot be performed satisfactorily, the polishing tool is reversed at that timing. Then, since the fluff has directionality in the direction opposite to the reverse direction, the plate-like body is polished while receiving a large rotational resistance from the plate-like body. The fluff eventually tries to change its direction to the reverse direction, but during polishing in which the fluff is subjected to a predetermined rotational resistance, that is, during polishing in which the rotational resistance of the fluff exceeds a predetermined value, the fluff The polishing rate is increased by the rotational resistance.

  Based on such verification results, the present invention is characterized in that the polishing tool is inverted when the rotational resistance of the polishing tool with respect to the plate-like body becomes equal to or less than the predetermined rotational resistance. Accordingly, when the polishing tool is inverted, the polishing rate increases and the polishing rate gradually decreases. However, when the rotational resistance of the polishing tool becomes a predetermined value or less, the polishing tool is inverted again to increase the polishing rate. . In this way, by repeating the reversal of the polishing tool based on the rotational resistance of the polishing tool received from the plate-like body, the polishing rate does not increase or decrease significantly, and therefore the polishing rate can be controlled to be substantially constant for polishing. .

  That is, in this invention, it is good also as a structure which reverses the rotation direction of the said grinding | polishing tool repeatedly with a predetermined period.

  Further, a lower limit value related to a load current value of a motor for rotating the polishing tool is determined in advance, a change in the load current at the time of polishing is monitored, and the rotation direction of the polishing tool is determined at a timing when the load current value reaches the lower limit value. It is good also as a structure reversed.

  Since it is difficult to directly measure the polishing rate during polishing, the load current value of the motor correlated with the polishing rate is measured, and when the load current value falls below a predetermined value, that is, the rotational resistance of the polishing tool The rotation direction of the polishing tool is reversed when is below a predetermined value. Thus, according to the present invention, the polishing rate can be controlled to be substantially constant. In addition, the direction of rotation of the polishing tool can be reversed at regular intervals.

  Further, the present invention may be configured such that the polishing tool revolves around a predetermined revolution center and the revolution direction is reversed simultaneously with the reversal of the rotation direction. In the case of a polishing tool that rotates and revolves, it is preferable that the revolving direction is reversed simultaneously with the reversal of the rotation direction from the balance relationship between the torque that rotates the revolving shaft and the torque that rotates the revolving shaft.

  In the present invention, a plurality of the polishing tools may be arranged along the moving direction of the plate-like body. The polishing tool of the present invention is suitable for a continuous polishing apparatus.

  Further, the present invention includes a truing step of pressing the polishing tool against a truing member and reshaping the polishing tool by relatively rotating the polishing tool and the truing member, and the plate performed after the truing step It is good also as a structure by which the autorotation direction of the said grinding | polishing tool at the time of grinding | polishing of a shaped object is set to a reverse direction with respect to the rotation direction at the time of the said truing process.

  The present invention relates to truing of an abrasive tool. The polishing tool is regularly trued by the truing member during the polishing of the plate-like body. When the plate-like body is polished after the truing process, the rotation direction of the polishing tool is changed with respect to the rotation direction during the truing process. And set it in the opposite direction. During truing, the fluff of the polishing tool has a direction that is inclined from the upstream side to the downstream side in the truing direction due to the relative rotation of the polishing tool and the truing member. Therefore, by rotating the polishing tool in the reverse direction with respect to the direction of fluff inclination generated during truing, the plate-like body is polished, so that the fluff polishes the plate-like body while receiving a large rotational resistance. Therefore, the polishing rate of the plate-like body is increased by the rotational resistance of the fluff.

  Moreover, this invention is good also as a structure by which the relative rotation direction of the said truing member at the time of the said truing process and the said polishing tool is set to the same direction as the autorotation direction of the said polishing tool immediately before a truing process.

  According to the present invention, the fluff of the polishing tool immediately before the truing process has a characteristic that it is inclined in the rotation direction of the polishing tool immediately before the truing process. When truing such a polishing tool, the relative rotation direction of the truing member and the polishing tool is set to the same direction as the direction of rotation of the polishing tool immediately before the truing process, thereby giving the polishing tool fluff during truing. The directionality can be further emphasized. That is, since the fluff inclination angle can be further increased, the rotational resistance of the fluff during polishing performed after the truing process can be further increased, and the polishing rate of the plate-like body can be significantly increased.

  In addition, truing is a work to remove the deflection of the working surface of the polishing tool by pressing the working surface of the polishing tool against the surface of a truing member such as a diamond grindstone and rotating the truing member and the polishing tool relative to each other. This refers to the work of correcting the shape of the working surface of the polishing tool used over time.

  As described above, according to the method for polishing a plate-like body of the present invention, the rotation direction of the polishing tool is reversed at a predetermined timing, so that the polishing rate of the plate-like body can be controlled to be substantially constant.

Bird's-eye view of glass substrate polishing apparatus of embodiment FIG. 1 is a plan view of the main part of the polishing apparatus shown in FIG. A longitudinal sectional view illustrating the structure of the polishing machine of the polishing apparatus shown in FIG. The figure which showed the revolution trajectory of the polishing tool of the polishing machine shown in FIG. Diagram showing the rotational resistance of the polishing tool against the glass substrate Diagram showing the rotational resistance of the polishing tool against the glass substrate Diagram showing the rotational resistance of the polishing tool against the glass substrate Diagram showing the rotational resistance of the polishing tool against the glass substrate Graph showing the relationship between motor rotation current and polishing rate Explanatory drawing showing the rotational relationship between the polishing tool and the truing member showing the first example of increasing the polishing rate Explanatory drawing showing the rotational relationship between the polishing tool and the truing member showing the first example of increasing the polishing rate Graph showing the change in polishing rate when the polishing tool is inverted after truing and the glass substrate is polished Graph showing the change in polishing rate when a glass substrate is polished without inverting the polishing tool after truing Explanatory drawing showing fuzzy wrinkles due to continued use of the polishing tool Explanatory drawing showing fuzzy wrinkles due to continued use of the polishing tool Explanatory drawing showing fuzzy wrinkles due to continued use of the polishing tool Explanatory drawing showing fuzzy wrinkles due to continued use of the polishing tool Explanatory drawing showing the rotational relationship between the polishing tool and the truing member showing the second example of increasing the polishing rate Explanatory drawing showing the rotational relationship between the polishing tool and the truing member showing the second example of increasing the polishing rate A graph showing the change in the polishing rate when the relative rotation direction of the truing member and the polishing tool during the truing process is set in the same direction as the rotation direction of the polishing tool immediately before the truing process.

  Hereinafter, preferred embodiments of a method for polishing a plate-like body according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a bird's-eye view of a polishing apparatus 10 to which a plate-like polishing method according to an embodiment is applied. FIG. 2 is a schematic plan view of the polishing apparatus 10 shown in FIG. 1, in which the contents relating to the shape, arrangement position, and operation of the polishing tool 12 are shown. The polishing apparatus 10 according to the embodiment includes a plurality of circular polishing units arranged along a conveyance path while continuously conveying a glass substrate G for liquid crystal display having a size of, for example, 2200 mm (width) × 2600 mm (length) or more. This is an apparatus for continuously polishing the glass substrate G with the tools 12, 12.

  As shown in FIG. 1, the glass substrate G to be polished is held on the suction sheet (not shown) adhered to the table 14 by suction and holds the surface opposite to the surface to be polished, as indicated by an arrow X in FIGS. The table 14 is continuously transported by a transport device to be described later. And the surface to be polished has a flatness required by the glass substrate G for liquid crystal display by each of the polishing tools 12, 12... Of the plurality of polishing machines installed above the transfer path during transfer of the table 14. Polished. The polished glass substrate G is cleaned by the cleaning device 16.

  As shown in FIG. 2, the polishing tools 12, 12... Are configured with a diameter D smaller than the width W of the glass substrate G, and are rotated around a predetermined rotation center by a rotation / revolution mechanism of a polishing machine described later. At the same time, the glass substrate G is polished while being revolved around a predetermined revolution center. In FIG. 2, circles indicated by solid lines indicate the current postures of the polishing tools 12, 12..., And many circles indicated by two-dot chain lines indicate that the glass substrate G is the polishing tools 12, 12. The edge part of the contact part is shown. As can be seen from these circles, the polishing tools 12, 12,... Are revolved around a predetermined revolution center.

  In addition, the polishing tools 12, 12... Are arranged in pairs with respect to the movement center line L of the glass substrate G, and are arranged in a zigzag pattern shifted in the moving direction. It arrange | positions so that the glass substrate G may be grind | polished beyond the movement center line L. FIG.

  According to the continuous polishing apparatus 10 configured as described above, a plurality of small polishing tools 12 having a diameter D smaller than the width W of the glass substrate G are arranged, and these polishing tools 12, 12. Are arranged in pairs on the left and right with respect to the moving center line L, and the polishing tool 12, 12... Polishes the glass substrate G beyond the center line L, thereby polishing the entire surface of the glass substrate G. it can.

  FIG. 3 is a sectional structural view of the polishing machine 20. The polishing machine 20 is installed so as to straddle the table 14.

  First, the conveying device for the table 14 will be described. A pair of guide blocks 22, 22 are provided at the lower part of the table 14, and the guide blocks 22, 22 are arranged on a base 24. , 26 are slidably engaged. A rack 28 is fixed to the lower center portion of the table 14 along the longitudinal direction of the table 14, and the rack 28 is engaged with a pinion 29. The pinion 29 is rotatably supported by the base 24, is connected to an output shaft of a motor (not shown), and is rotated by the driving force of the motor. Thereby, the rack 28 is sent to the pinion 29, and the table 14 is conveyed at a predetermined speed in the X direction shown in FIGS.

  As the table 14 is conveyed, the glass substrate G held on the suction sheet on the table 14 sequentially passes below the polishing machines 20, 20..., And the polishing tools 12, 12 of the polishing machines 20, 20. Polished by small amounts. And finally, the thing of the flatness requested | required with the glass substrate for liquid crystal displays is manufactured. The transport speed of the table 14 is controlled so that it can be changed depending on the polishing situation. Further, as the polishing tool 12, a foamed polyurethane pad, a suede pad, or the like is applied, and the slurry supplied at the time of polishing contains free abrasive grains such as cerium oxide or zirconium oxide.

  The polishing machine 20 has a main shaft 30 provided above the table 14 and orthogonal to the table 14. The main shaft 30 is rotatably supported by a main body casing 34 via bearings 32, 32 arranged up and down, and the main body casing 34 is fixed to a pair of posts 36, 36 arranged on both sides thereof. Yes. In addition, pistons 40 of hydraulic jacks 38 installed on the base 24 are connected to the lower portions of the posts 36 and 36, respectively. Therefore, when the pistons 40 and 40 are simultaneously expanded and contracted, the main body casing 34 is moved up and down via the posts 36 and 36. As a result, the polishing head 42 provided with the polishing tool 12 is moved forward and backward with respect to the table 14.

On the other hand, the main shaft 30 is formed with an insertion hole 30 </ _b > A having a central axis O ₂ eccentric with respect to the central axis O ₁ of the main shaft 30. The insertion hole 30A is inserted the output shaft 44, output shaft 44, as the center axis thereof coincides with the axis O _2, rotatably on the main shaft 30 via a bearing 46, 46 disposed above and below It is supported.

A gear 48 is provided on the upper peripheral portion of the main shaft 30. A gear 50 is engaged with the gear 48, and a gear 54 is connected to the gear 50 via a shaft 52. An output gear 58 is engaged with the gear 54 via an idle gear 56, and the output gear 58 is fixed to the motor output shaft 62 of the revolution motor 60. As a result, the driving force of the motor 60 is decelerated via the gears 58, 56, 54, 50 and 48 and transmitted to the main shaft 30, so that the main shaft 30 is rotated at a predetermined rotational speed. When the main shaft 30 is thus rotated, the output shaft 44 revolves along a circumference centered on the axis O ₁ of the main shaft 30. That is, the polishing tool 12 revolves around the axis O ₁ .

  A polishing head 42 formed in a circular shape is connected to a lower end portion of the output shaft 44 via a rotary joint 64. The polishing head 42 includes an upper surface plate 66, a polishing surface plate 68, a polishing tool 12, and air springs 70, 70.

The upper surface plate 66 is made of stainless steel having high rigidity for the purpose of preventing chatter. The polishing surface plate 68 has a high rigidity structure made of cast iron or stainless steel, and is connected to the upper surface plate 66 via air springs 70, 70. These air springs 70, 70... Are disposed at a predetermined interval on the circumference centering on the axis O ₂ of the polishing head 42, and an air passage (not shown) formed in the upper surface plate 66. And it is connected to an air pump (not shown) via a rotary joint 64. Therefore, when the compressed air from the air pump is supplied to the air springs 70, 70... Via the rotary joint 64 and the air passage, the air springs 70, 70. Therefore, the spring force of the air springs 70, 70... Is transmitted to the polishing tool 12 via the polishing surface plate 68, so that polishing pressure is applied to the polishing tool 12. The polishing pressure is adjusted by controlling the air pressure supplied to the air springs 70, 70.

On the other hand, the upper end portion of the output shaft 44 is connected to the output shaft 76 of the motor 74 for rotation through a universal joint 72. Accordingly, the output shaft 44 rotates about the axis O ₂ by the driving force of the motor 74. That is, the polishing tool 12 rotates about the axis O ₂ . Even if the output shaft 44 is revolving around the axis O ₁ , the output shaft 44 is connected to the output shaft 76 of the motor 74 via the universal joint 72, so that the polishing tool 12 rotates without trouble. Exercise.

  Next, the operation of the polishing machine 20 will be described.

  First, the main body casing 34 is moved up and down by extending and contracting the piston 40 of the hydraulic jack 38 of the polishing machine 20 to adjust the height position of the polishing head 42 with respect to the table 14. Then, the amount of air supplied to the air spring 70 is adjusted, and the polishing pressure is set for each of the polishing machines 20, 20.

Next, the table 14 is transported in the transport direction. Then, at the same time, by driving the revolving motor 60 and the self-rotating motor 74 of the grinding machine 20, respectively, the polishing tool 12 as shown in FIG. 4, with revolving motion around the axis O _1, axis O ₂ The glass substrate G that has been transported by the table 14 is polished while rotating around the center.

  As described above, in the polishing machine 20, the glass substrate G is polished while the polishing tool 12 rotates and revolves. Therefore, the glass substrate G is polished with a combined locus of the revolution locus and the rotation locus of the polishing tool 12. Therefore, according to the continuous polishing apparatus 10 configured by arranging a plurality of polishing machines 20 side by side, the polishing efficiency can be improved without increasing the revolution speed of the polishing tool 12. Moreover, since it is not necessary to raise the polishing pressure of the polishing tool 12 more than necessary, the flatness of the polished surface of the glass substrate G is also improved.

  By the way, in the conventional polishing apparatus, since the rotation direction of the polishing tool is set to only one of the clockwise direction and the counterclockwise direction, the polishing rate of the glass substrate decreases as the polishing time elapses. When the polishing rate falls below a predetermined threshold, the polishing pad is trued. Further, even if the conventional polishing apparatus does not require truing of the polishing tool, the polishing rate decreases with the lapse of the polishing time, so that the polishing rate cannot be made constant at a constant rate.

  The polishing apparatus 10 of the embodiment has been made for the purpose of eliminating the disadvantages of the conventional polishing apparatus and polishing the glass substrate while controlling the polishing rate to be substantially constant. That is, in the polishing method by the polishing apparatus 10 of the embodiment, the rotation direction of the polishing tool 12 is reversed at a predetermined timing.

  The reason why the polishing rate can be controlled to be substantially constant by reversing the polishing tool 12 will be described.

  As shown in FIG. 5A, when the polishing tool 12 is macroscopically viewed and separated into a polishing tool base (hard portion) 12A and a fluff (soft portion) 12B, the fluff 12B that actually polishes the glass substrate G is as follows. It has directionality by polishing or truing. That is, as shown in FIG. 5B, the fluff 12B is inclined in a direction opposite to the grinding direction when viewed from the polishing tool in the direction of the glass substrate G. If polishing is continued in such a direction, the rotational resistance of the fluff 12B with respect to the glass substrate G decreases, so the polishing rate decreases with the lapse of polishing time. Therefore, when the rotational resistance of the fluff 12B with respect to the glass substrate G becomes equal to or less than a predetermined value, that is, when polishing with the fluff 12B cannot be performed satisfactorily, the rotation direction of the polishing tool 12 is reversed at that timing. Then, as shown in FIG. 5C, the fluff 12B has a direction opposite to the reverse direction, so that the glass substrate G is polished while receiving a large resistance increase from the glass substrate G. Become. As shown in FIG. 5D, the fluff 12B tries to change its direction in the reverse direction, but during the polishing in which the fluff 12B is subjected to a predetermined rotational resistance, that is, the rotational resistance of the fluff 12B is predetermined. During polishing exceeding the value, the polishing rate increases due to the rotational resistance of the fluff 12B.

  Based on such verification results, the polishing method of the embodiment is configured so that when the rotational resistance of the polishing tool 12 with respect to the glass substrate G becomes equal to or less than the predetermined resistance, the rotation direction of the polishing tool 12 is normal rotation (normal rotation). ) To reverse rotation. As a result, when the polishing tool 12 is inverted, the polishing rate increases, and the polishing rate gradually decreases. However, when the rotational resistance of the polishing tool 12 becomes a predetermined value or less, the polishing tool 12 is turned on again. Invert to increase the polishing rate. In this way, by repeating the reversal of the polishing tool 12 based on the rotational resistance of the polishing tool 12 received from the glass substrate G, the polishing rate does not increase or decrease significantly, and thus the polishing rate is controlled to be substantially constant for polishing. Can do.

  According to the polishing method of the embodiment, as shown in the graph of FIG. 6, the load current value (load current value) of the motor 74 (see FIG. 3) that rotates the polishing tool 12 is not more than a predetermined value (TH value). When this happens, the direction of rotation of the polishing tool 12 is reversed. That is, the polishing apparatus 10 according to the embodiment includes a control unit that reverses the rotation direction of the polishing tool 12 when the load current value of the motor 74 (see FIG. 3) becomes a predetermined value (TH value) or less. . The polishing rate may be directly measured during the polishing of the glass substrate G, and the rotational direction of the polishing tool 12 may be reversed based on the polishing rate. However, the polishing rate may be directly measured during the polishing of the glass substrate G. Since it is difficult, the rotation current value of the motor 74 having a correlation with the polishing rate is measured, and the polishing tool 12 is inverted based on the current value.

  Referring to the graph of FIG. 6, the horizontal axis is the time axis, and the right vertical axis indicates the rotation current value of the motor 74. This autorotation current value is also referred to as a load current value because it can vary depending on the state of the load when the motor is driven at a predetermined voltage. The left vertical axis shows the polishing rate (unit: μm / min). Further, according to FIG. 6, the threshold value of the rotation current value for switching the rotation direction of the motor 74 is set to a predetermined lower limit value (TH value in the figure).

  The threshold value of the rotation current value is preferably a current value of 65% of the rotation current value immediately after the inversion. A current value of 70% is more preferable, and a current value of 80% is particularly preferable.

  Further, when the direction of rotation of the polishing tool is reversed every predetermined time, the minimum time of the time required from the time immediately after the reversal to the threshold value of the rotation current value can be reversed. By determining the inversion time in this way, the polishing rate can be made substantially constant even if the time required from immediately after the inversion to the threshold value of the autorotation current value varies.

  Further, in this experimental example, the rotation speed, the revolution speed, the pressure of the polishing tool 12 against the glass substrate G, and the slurry supply amount are set to predetermined values, respectively.

  As shown in the figure, in the present invention, motor drive control is set so that the motor 74 reverses from normal rotation to reverse rotation and from reverse rotation to normal rotation when the autorotation current value becomes equal to or less than the TH value. Therefore, as shown in the graph of the same figure, the rotation current value (polishing rate) increases, and the rotation current value (polishing rate) decreases with the lapse of the polishing time. Then, when the autorotation current becomes equal to or less than the TH value again, the motor 74 reverses and the autorotation current value (polishing rate) increases again. Thus, the autorotation current value and the polishing rate have a positive correlation. Then, a threshold value (TH value) of the rotation current value that can be directly controlled is set, and the rotation direction of the polishing tool 12 by the motor 74 is reversed based on the threshold value. With this configuration, it is possible to suppress the degree of vertical fluctuation (bar graph) of the polishing rate shown in FIG.

  Further, according to the polishing method of the embodiment, the control unit described above also controls the motor 60 to reverse the revolution direction of the polishing tool 12 simultaneously with the reversal of the rotation direction of the polishing tool 12. In the case of a device that rotates and revolves the polishing tool 12 as in the polishing machine 20 of the embodiment, the torque for rotating the rotation shaft (output shaft 44: see FIG. 3) and the revolution shaft (main shaft 30: see FIG. 3). ) Is preferably reversed at the same time as the rotation direction is reversed.

  In the embodiment, the continuous polishing apparatus 10 in which a plurality of polishing machines 20 are arranged side by side has been described. However, even if the polishing method of the present invention is applied to a polishing apparatus including one polishing machine 20. In addition, the polishing machine 20 in which the polishing tool 12 rotates and revolves has been described. However, the polishing method of the present invention may be applied to a polishing apparatus in which the polishing tool 12 only rotates.

  In the above embodiment, the example in which the rotation direction and the revolution direction of the polishing tool 12 are reversed at a predetermined timing to control the polishing rate of the glass substrate G to be substantially constant has been described. On the other hand, also in the truing of the polishing tool 12 that is periodically performed, the polishing rate of the glass substrate G by paying attention to the rotation direction of the polishing tool 12 immediately after truing and the rotation direction of the polishing tool 12 immediately before truing. Can be raised.

  That is, the polishing method of the embodiment includes a truing process. The truing process is a process of reshaping the polishing tool 12 by pressing the polishing tool 12 against the truing member 80 and rotating or revolving the polishing tool 12 and the truing member 80 relatively as shown in FIG. 7A. In FIG. 7A, the polishing tool 12 is rotated or revolved in the direction of arrow A with respect to the fixed truing member 80 to perform truing. However, the polishing tool 12 is fixed and the truing member 80 is rotated or rotated. It may be revolved, and both the polishing tool 12 and the truing member 80 may be rotated. As the truing member 80, a diamond grindstone configured in a disk shape or a rectangular shape can be exemplified.

  As an example of increasing the polishing rate, as shown in FIG. 7B, the rotation direction indicated by the arrow B of the polishing tool 12 at the time of polishing the glass substrate G performed after the truing process is rotated by the rotation indicated by the arrow A in the truing process shown in FIG. 7A. The direction is set opposite to the direction.

  The polishing tool 12 is periodically trued by the truing member 80 when the glass substrate G is polished. At the time of polishing the glass substrate G performed after the truing process, the rotation direction of the polishing tool 12 is rotated in the truing process. Set in the opposite direction to the direction.

As shown in FIG. 7A, during truing, the fluff 12B of the polishing tool 12 is inclined (inclination angle θ ₂ ) from the upstream side to the downstream side in the truing direction due to the relative rotation of the polishing tool 12 and the truing member 80. Has the direction. Therefore, the glass substrate G is polished by rotating the polishing tool 12 in the opposite direction with respect to the inclination direction of the fluff 12B generated during truing. Accordingly, as shown in FIG. 7B, the fluff 12B polishes the glass substrate G while receiving a large rotational resistance. Therefore, the polishing rate of the glass substrate G is increased by the rotational resistance of the fluff 12B.

  This will be specifically described with reference to the graph of FIG.

  The horizontal axis t of the graph in the figure is the time axis, and the left vertical axis indicates the polishing rate (unit: μm / min). As shown in this graph, the glass substrate G is polished by repeating the normal rotation and inversion of the polishing tool 12, and the truing of the polishing tool 12 is performed as shown in FIG. 7A at the timing (A) of the polishing process. Thereafter, as shown in FIG. 7B, the direction of rotation of the polishing tool 12 is set to be opposite to the direction during truing, and the polishing of the glass substrate G is continued. As shown in the graph of FIG. 8, it can be seen that the peak value (a) of the polishing rate after truing is significantly higher than the peak value (b) of the polishing rate due to normal normal rotation and reversal operations.

  A comparative example will be described using the graph of FIG.

  In this comparative example, the direction of rotation of the polishing tool 12 during truing is the same as the direction of rotation of the polishing tool 12 immediately after truing. According to this comparative example, the peak value of the polishing rate immediately after truing increases from the b value to the c value by reshaping the polishing tool 12 by truing at timing (A), but the amount of increase (c value−b value). ) Is smaller than the amount of increase (a value-b value) of the embodiment shown in FIG.

  By the way, in the embodiment of FIGS. 7A and 7B, a great effect can be obtained when the polishing tool 12 is in a new state or just after dressing. However, if the polishing tool 12 is continuously used for a long time, the wrinkles of the fluff 12B returned by polishing cannot be sufficiently returned by truing, and the polishing rate cannot be significantly increased.

  That is, as shown in FIG. 10A, the polishing tool 12 is rotated in the direction of arrow A during truing, and the polishing tool 12 is inverted in the direction of arrow B as shown in FIG. If polishing is continued in this state, as shown in FIG. 10C, the fluff 12B of the polishing tool 12 inclines along the polishing direction, and as a result, the polishing rate decreases. Then, as shown in FIG. 10D, even if truing is performed in the direction of arrow A thereafter, the wrinkles of the fluff 12B returned by polishing cannot be returned to the state shown in FIG. 10A. Therefore, it becomes impossible to increase the polishing rate of polishing performed immediately after that.

  In such a case, the relative rotation direction of the truing member and the polishing tool 12 at the time of the truing process is set to the same direction as the rotation direction of the polishing tool 12 immediately before the truing process.

The fluff 12B of the polishing tool 12 immediately before the truing process has a characteristic that it is inclined in the rotation direction of the polishing tool 12 immediately before the truing process. In truing such a polishing tool 12, by setting the relative rotational direction of the truing member and the polishing tool 12 to be the same as the direction of rotation of the polishing tool 12 immediately before the truing process, the polishing tool 12 during truing. The directionality given to the fluff 12B can be further emphasized. That is, as shown in FIG. 11A, the inclination angle θ ₁ of the fluff 12B can be made larger than the inclination angle θ ₂ shown in FIG. 7A, so that the polishing tool 12 is inverted after the truing process as shown in FIG. 11B. It is possible to further increase the rotational resistance of the fluff 12B when it is made to move. Therefore, the polishing rate of the glass substrate G can be significantly increased.

  In FIG. 11A, the truing direction is indicated by an arrow B, and in FIG. 11B, the polishing direction is indicated by an arrow A. That is, an example in which the truing direction is reversed with respect to FIGS. 7A and 7B and FIGS. 10A to 10D and the rotation direction of the polishing tool 12 performed immediately thereafter is also reversed.

  This will be specifically described with reference to the graph of FIG.

  The horizontal axis t of the graph in the figure is the time axis, and the left vertical axis indicates the polishing rate (unit: μm / min). As shown in this graph, the glass substrate G is polished by repeating the normal rotation and inversion of the polishing tool 12, and the truing shown in FIG. 7A is performed at the timings (A) and (B) of the polishing process. Then, at the subsequent timing (C), after performing the truing shown in FIG. 11A, the polishing tool 12 is inverted as shown in FIG. 11B and the polishing is continued. Thus, as shown in the graph of FIG. 12, it can be seen that the peak value (d) of the polishing rate after truing in FIG. 11A is significantly higher than the previous polishing rate value (e). The truing performed at timings (D) and (E) thereafter is the truing shown in FIGS. 7A and 7B. That is, the truing shown in FIG. 11A may be performed for each truing, but is preferably performed intermittently when the polishing rate falls below a predetermined value or when necessary.

  Although this application has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on June 4, 2009 (Japanese Patent Application No. 2009-135108), the contents of which are incorporated herein by reference.

  The object to be polished by the plate polishing apparatus of the present invention is not limited to a glass substrate for FPD, and may be a general glass plate for building materials, mirrors, etc. It may be a target.

DESCRIPTION OF SYMBOLS 10 ... Polishing apparatus 12 ... Polishing tool 12A ... Polishing tool base 12B ... Fluff 14 ... Table 16 ... Cleaning apparatus 20 ... Polishing machine 22 ... Guide block 24 ... Base 28 ... Rack 29 ... Pinion 30 ... Main shaft 32 ... Bearing 34 ... Main body Casing 36 ... Post 38 ... Hydraulic jack 40 ... Piston 42 ... Polishing head 44 ... Output shaft 46 ... Bearing 48 ... Gear 50 ... Gear 52 ... Shaft 54 ... Gear 56 ... Idle gear 58 ... Output gear 60 ... Revolution motor 62 ... Motor Output shaft 64 ... Rotary joint 66 ... Upper surface plate 70 ... Air spring 72 ... Universal joint 74 ... Motor for rotation 76 ... Output shaft 80 ... Truing member

Claims (7)

In the plate body polishing method of polishing the plate body with a rotating polishing tool while moving the plate body in a predetermined direction,
A polishing method for a plate-like body, wherein the rotation direction of the polishing tool is reversed at a predetermined timing.   The method for polishing a plate-like body according to claim 1, wherein the rotating direction of the polishing tool is repeatedly reversed at a predetermined cycle.   A lower limit value related to the load current value of the motor that rotates the polishing tool is determined in advance, a change in the load current during polishing is monitored, and the rotation direction of the polishing tool is reversed when the load current value reaches the lower limit value. The method for polishing a plate-like body according to claim 1.   The said grinding | polishing tool revolves around a predetermined revolution center, The grinding | polishing method of the plate-shaped body of Claim 1 or 2 reverse | reversed simultaneously with the reversal of a rotation direction.   The said grinding | polishing tool is the grinding | polishing method of the plate-shaped body of any one of Claims 1-3 arrange | positioned along the moving direction of a plate-shaped body. A truing step of pressing the polishing tool against a truing member and reshaping the polishing tool by rotating the polishing tool and the truing member relatively;
The rotation direction of the said grinding | polishing tool at the time of grinding | polishing of the said plate-shaped body performed after the said truing process is set to a reverse direction with respect to the rotation direction at the time of the said truing process. Polishing method for plate-like body.   The polishing of the plate-shaped body according to claim 6, wherein a relative rotation direction of the truing member and the polishing tool during the truing process is set in the same direction as a rotation direction of the polishing tool immediately before the truing process. Method.

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