Grinding equipment

Abstract

To provide a grinding device configured so that a residual quantity of a grinding stone therein can be calculated in a short time.SOLUTION: A grinding device 1, which is provided with a chuck table 10, a grinding mechanism 20 and a moving mechanism 30, is further provided with a grinding wheel 25 constituted of an annular base 251 and a plurality of segment grindstones 252; a sensing mechanism 40 constituted of a light emitting part 41 and a light receiving part 42; a grindstone lower surface recognizing part 51 that recognizes lower surfaces 256 of the segment grindstones 252 on the basis of amounts of light received by the light receiving part 42; a base lower surface recognizing part 52 that recognizes a lower surface 255 of the base 251; and a residual amount calculating part 53 that calculates residual amounts of the segment grindstones 252. The residual amount calculating part 53 calculates, as the residual amounts of the segment grindstones 252, a difference Δh between a first position h1 of the grinding mechanism 20 at which the grindstone lower surface recognizing part 51 recognizes the lower surfaces 256 of the segment grindstones 252 and a second position h2 of the grinding mechanism 20 at which the base lower surface recognizing part 52 recognizes the lower surface 255 of the base 251.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grinding device equipped with a remaining amount calculation unit that calculates the remaining amount of segment grinding stones of a grinding wheel. [Background technology]

[0002] When the grinding wheel wears down by a certain amount due to grinding processing, the grinding wheel is replaced with a new one, but the remaining amount of grinding wheel is calculated by measuring the remaining amount of grinding wheel on the grinding wheel immediately after replacement with a vernier caliper or the like, and subtracting the amount of wear of the grinding wheel worn down by grinding processing from the remaining amount of grinding wheel immediately after replacement.The grinding wheel is then replaced when the calculated current remaining amount of grinding wheel falls below a predetermined value.

[0003] However, as mentioned above, there is a problem in that an error may occur between the remaining amount of the grinding wheel measured with a vernier caliper or the like immediately after replacing the grinding wheel and the actual remaining amount of the grinding wheel.

[0004] Therefore, Patent Document 1 proposes a grinding device that measures the height position of the grinding mechanism using a height measuring means when it is optically detected by a transmission photosensor or the like that the underside of the grinding wheel base and the underside of the grinding wheel have reached a predetermined position, and calculates the difference between the heights measured at each timing as the remaining amount of the grinding wheel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-097089 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the grinding device proposed in Patent Document 1, the operation of detecting the underside of the grinding wheel base and the operation of detecting the underside of the grinding wheel must be performed separately, which results in the problem that it takes time to calculate the remaining amount of grinding wheel.

[0007] Therefore, there is a need for a grinding device to calculate the remaining amount of grinding wheel in a short time. [Means for solving the problem]

[0008] The present invention provides a grinding device comprising: a chuck table for holding a workpiece on a holding surface; a grinding mechanism for grinding the workpiece held on the holding surface with a plurality of segmented grindstones arranged in a circle on a grinding wheel attached to a spindle; and a moving mechanism having a position recognition unit for moving the grinding mechanism in a direction perpendicular to the holding surface and recognizing the height position of the grinding mechanism, wherein the grinding wheel is composed of an annular base mounted on a mount connected to the tip of the spindle and a plurality of segmented grindstones arranged in a circle on the underside of the base with gaps between them; a detection mechanism comprising a light-emitting unit and a light-receiving unit arranged opposite to each other and spaced apart in the radial direction of the base so that the base of the grinding wheel moved by the moving mechanism can enter; a grinding wheel undersurface recognition unit that recognizes the underside of the segment grinding wheel based on the amount of light received by the light receiving unit; a base undersurface recognition unit that recognizes the underside of the base based on the amount of light received by the light receiving unit; and a remaining amount calculation unit that calculates the remaining amount of the segment grinding wheel, wherein the remaining amount calculation unit lowers the grinding mechanism toward the detection mechanism using the movement mechanism and calculates the remaining amount of the segment grinding wheel as the difference between a first position of the grinding mechanism recognized by the grinding wheel undersurface recognition unit when the grinding wheel undersurface recognition unit recognizes the underside of the segment grinding wheel of the rotating grinding wheel, and a second position of the grinding mechanism recognized by the base undersurface recognition unit when the grinding mechanism is lowered and the base undersurface recognition unit recognizes the underside of the base of the rotating grinding wheel. [Effects of the Invention]

[0009] According to the present invention, the grinding mechanism is lowered only once, and the height position (first position) of the underside of the segment grinding stone of the grinding wheel and the height position (second position) of the underside of the base are optically recognized by the detection mechanism, and the difference in height between the first position and the second position is calculated as the remaining amount of segment grinding stone, so that the remaining amount of segment grinding stone can be accurately determined in a short time. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cutaway perspective view of a grinding device according to the present invention; [Figure 2] 3 is a planar cross section showing the arrangement of segment grinding stones in a grinding wheel of a grinding device according to the present invention. [Figure 3] 3(a) and 3(b) are cross-sectional views taken along the line AA in FIG. 2, illustrating the positional relationship between the light projecting unit and the light receiving unit of the detection mechanism and the grinding wheel. [Figure 4] FIG. 10 is a diagram showing the relationship between the height position of the grinding mechanism and the output voltage of the detection mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Configuration of grinding equipment) The grinding apparatus 1 shown in Figure 1 is used to grind a disk-shaped wafer 100, which is a workpiece, and is equipped with a chuck table 10 that holds the wafer 100 on its upper circular holding surface 11, a grinding mechanism 20 that grinds the wafer 100 held by suction on the holding surface 11 of the chuck table 10, a moving mechanism 30 that moves (raises and lowers) the grinding mechanism 20 in a direction perpendicular to the holding surface 11 of the chuck table 10 (Z-axis direction), a detection mechanism 40 that optically detects the underside 255 (see Figure 3) of the base 251 and the underside 256 (see Figure 3) of the segmented grinding wheel 25 of the grinding mechanism 20, and a control unit 50 that calculates the remaining amount of the segmented grinding wheel 252 from the position (first position) of the underside 256 of the segmented grinding wheel 252 and the position (second position) of the underside 255 of the base 251 detected by the detection mechanism 40.

[0012] 1, a plurality of devices (not shown) are formed on the surface facing downward in the state shown in Fig. 1, and these devices are protected by a protective tape (not shown) attached to the surface of the wafer 100. The front surface (the lower surface in Fig. 1) of the wafer 100 is suction-held on the holding surface 11 of the chuck table 10, and the back surface (the upper surface in Fig. 1) is ground by the segment grindstone 252 of the grinding mechanism 20.

[0013] The chuck table 10 is a disk-shaped member, and a disk-shaped porous member 13 made of porous ceramic or the like is incorporated into a circular recess 12 formed in the center thereof. The upper surface of the porous member 13 forms a holding surface 11 that suction-holds the disk-shaped wafer 100. Although not shown, the porous member 13 is connected to a suction source (not shown), such as a vacuum pump.

[0014] The chuck table 10 is rotated at a predetermined speed around its axis on the XY plane (horizontal plane) by a motor (not shown) that is a drive source disposed vertically below the chuck table 10.

[0015] 1, the grinding apparatus 1 according to this embodiment includes a rectangular box-shaped base 2 that is long in the Y-axis direction (front-rear direction), and a rectangular block-shaped internal base 3 is housed inside the base 2. A horizontal movement mechanism 60 is provided on the internal base 3 for moving the chuck table 10 along the Y-axis direction (front-rear direction). The horizontal movement mechanism 60 includes a block-shaped slider 61, and the slider 61 is slidable in the Y-axis direction along a pair of left and right guide rails 62 that are arranged parallel to each other along the Y-axis direction (front-rear direction). Therefore, the chuck table 10 supported by the slider 61 and a motor (not shown) and the like are slidable along the Y-axis direction together with the slider 61.

[0016] A rotatable ball screw shaft 63 extending in the Y-axis direction (front-rear direction) is disposed between a pair of left and right guide rails 62 on the internal base 3, and one end of the ball screw shaft 63 in the Y-axis direction (the left end in FIG. 1) is connected to a motor 64, which serves as a drive source and can rotate forward and backward. The other end of the ball screw shaft 63 in the Y-axis direction (the right end in FIG. 1) is rotatably supported by a bearing 65 erected on the internal base 3. A nut member (not shown) protruding downward from the slider 61 is threadedly inserted and fitted onto the ball screw shaft 63.

[0017] Therefore, when the motor 64 is rotated forward or backward to rotate the ball screw shaft 63 forward or backward, a nut member (not shown) threadedly inserted into the ball screw shaft 63 slides together with the slider 61 in the Y-axis direction (front-back direction) along the ball screw shaft 63, and the chuck table 10 also moves integrally along the Y-axis direction together with the slider 61. As a result, the wafer 100, which is the workpiece suction-held on the holding surface 11 of the chuck table 10, also moves along the Y-axis direction.

[0018] 1, a rectangular opening 4 that is long in the Y-axis direction is formed in the upper surface of the base 2, and a chuck table 10 is housed in this opening 4. The periphery of the chuck table 10 in opening 4 that opens in the upper surface of the base 2 is covered with a rectangular plate-shaped cover 5, and the front and rear portions (-Y direction and +Y direction) of cover 5 of opening 4 are covered by bellows-shaped extendable covers 6 and 7 that move and extend together with cover 5. Therefore, regardless of the position of chuck table 10 when it moves in the Y-axis direction, opening 4 of base 2 is always covered by cover 5 and extendable covers 6 and 7, and therefore, the intrusion of foreign matter into base 2 is reliably prevented by cover 5 and extendable covers 6 and 7.

[0019] As shown in FIG. 1, a rectangular box-shaped column 8 is erected vertically on the +Y axis direction end (rear end) of the top surface of the base 2, and a moving mechanism 30 is provided on the -Y axis direction end face (front face) of this column 8, which moves the grinding mechanism 20 up and down along the Z axis direction (up and down direction).

[0020] The grinding mechanism 20 includes a spindle 21 having a rotation center axis in the Z-axis direction, a housing 22 that rotatably supports the spindle 21, a spindle motor 23 that rotationally drives the spindle 21, a mount 24 connected to the lower end of the spindle 21, and a grinding wheel 25 that is detachably attached to the lower surface of the mount 24. Here, the grinding wheel 25 includes a base 251 and a plurality of segmented grinding stones 252 having a substantially rectangular parallelepiped shape and arranged in an annular shape on the lower surface of the base 251. Note that each segmented grinding stone 252 is a processing tool for grinding the wafer 100, and its lower surface 256 (see FIG. 3) forms a grinding surface that comes into contact with the wafer 100.

[0021] Here, the arrangement state of the plurality of segment grinding wheels 252 is shown in Fig. 2. In the example shown in Fig. 2, 36 segment grinding wheels 252 with a circumferential length of 253 are arranged in a circular shape at equal angular pitches (10° pitches) in the circumferential direction, and a circumferential gap 254 is formed between each two adjacent segment grinding wheels 252. Note that the number of segment grinding wheels 252 is not limited to 36 and can be any number.

[0022] The movement mechanism 30 moves the grinding mechanism 20 up and down in a direction (Z-axis direction) perpendicular to the holding surface 11 of the chuck table 10, and moves a rectangular plate-shaped lift plate 31 and a holder 26 supporting the housing 22 up and down in the Z-axis direction along a pair of left and right guide rails 32, together with the housing 22 and the spindle 21, spindle motor 23, grinding wheel 25, etc. held by the housing 22. Here, the pair of left and right guide rails 32 are disposed perpendicular to the front surface of the column 8 and parallel to each other, and each of these guide rails 32 has a guide groove 321 (only one of which is shown in FIG. 1) formed along the up-down direction.

[0023] In addition, engagement protrusions (not shown) are provided above and below the locations of the lifting plate 31 corresponding to the guide grooves 321 of the pair of left and right guide rails 32, respectively, protruding rearward (in the +Y-axis direction), and these engagement protrusions engage with the guide grooves 321 formed in each of the pair of left and right guide rails 32.

[0024] 1, a rotatable ball screw shaft 33 is installed vertically along the Z-axis direction between the pair of left and right guide rails 32, and the upper end of the ball screw shaft 33 is connected to a motor 34, which serves as a drive source and can rotate forward and backward. The motor 34 is mounted in a vertical position via a rectangular plate-shaped bracket 35 attached to the upper surface of the column 8. The motor 34 is provided with an encoder 36 that detects the rotation angle of the motor 34, and the encoder 36 and the motor 34 are electrically connected to a control unit 50.

[0025] The lower end of the ball screw shaft 33 is rotatably supported on the column 8 by a bearing 37. A nut member (not shown) is threadably inserted into the ball screw shaft 33 and protrudes horizontally rearward (in the +Y-axis direction) from the rear surface of the lifting plate 31.

[0026] 1, a scale 70 is fixed to the front surface (the surface in the -Y-axis direction) of one of the guide rails 32, and a reading unit 71 that measures the height position of the grinding mechanism 20 (grinding wheel 25) is attached to the side surface on the +X-axis direction side of the lifting plate 31. This reading unit 71 is equipped with, for example, a recognition mechanism that optically reads the values ​​of the scale marks engraved on the scale 70, and can recognize the height positions of the base 251 of the grinding wheel 25 of the grinding mechanism 20 and the segment grindstone 252 by optically recognizing the scale marks on the scale 70. The reading unit 71 is electrically connected to the control unit 50. In addition, if the scale 70 and the reading unit 71 are not provided, the control unit 50 detects the rotation angle of the encoder 36 (by optically recognizing the scale) and recognizes the height position of the base 251 of the grinding wheel 25 of the grinding mechanism 20 and the segment grinding stone 252.

[0027] The detection mechanism 40 is composed of a transmission-type photosensor (photointerrupter) that optically detects the positions of the underside 255 (see FIG. 3) of the base 251 provided on the grinding wheel 25 and the underside 256 (see FIG. 3) of the segment grinding wheel 252, and is attached to a cover 4 provided around the chuck table 10 as shown in FIG. 1. As shown in FIGS. 2 and 3, the detection mechanism 40 includes a light-emitting element (light-emitting device) 41 and a light-receiving element (light-receiving element) 42 disposed opposite each other in the radial direction of the grinding wheel 25. When the light-receiving element 42 receives light 411 emitted from the light-emitting element 41 toward the light-receiving element 42, the light-receiving element 42 generates a voltage corresponding to the amount of light received. The light-emitting element 41 is disposed radially inside the grinding wheel 25, and a recessed gap 43 is formed between the light-emitting element 41 and the light-receiving element 42 disposed radially outside the grinding wheel 25, allowing the segment grinding wheel 252 to enter.

[0028] The control unit 50 controls the driving of the spindle motor 23 of the grinding mechanism 20 and the motor 34 of the movement mechanism 30 shown in Fig. 1, and has the function of calculating the remaining amount of the segmented grindstone 252 based on the amount of light received (output voltage value) by the light receiving unit 42 of the detection mechanism 40. Specifically, as shown in Fig. 1, the control unit 50 is provided with a grindstone lower surface recognition unit 51 that recognizes the height position (first position of the grinding mechanism 20) of the lower surface 256 (see Fig. 3) of the segmented grindstone 252 based on the amount of light received (output voltage value) by the light receiving unit 42 of the detection mechanism 40, a base lower surface recognition unit 52 that recognizes the height position (second position of the grinding mechanism 20) of the lower surface 255 (see Fig. 3) of the base 251 based on the amount of light received (output voltage value) by the light receiving unit 42 of the detection mechanism 40, and a remaining amount calculation unit 53 that calculates the difference between the first position and the second position of the grinding mechanism 20 as the remaining amount of the segmented grindstone 252.

[0029] (Action of grinding equipment) Next, grinding of the wafer 100 by the grinding apparatus 1 configured as above will be described.

[0030] When grinding the wafer 100, the wafer 100 is placed face down on the holding surface 11 of the chuck table 10. Then, a suction source (not shown) connected to the porous member 13 of the chuck table 10 is driven to evacuate the porous member 13. This generates a negative pressure in the porous member 13, and the wafer 100 placed on the upper surface (holding surface 11) of the porous member 13 is suction-held onto the holding surface 11 by the negative pressure.

[0031] From the above state, the horizontal movement mechanism 60 is driven to move the chuck table 10 in the +Y-axis direction (rearward), and the wafer 100 suction-held on the chuck table 10 is positioned below the grinding wheel 25 of the grinding mechanism 20. That is, when the motor 64 is started and the ball screw shaft 63 is rotated, the slider 61, to which a nut member (not shown) threadably inserted onto the ball screw shaft 63 is attached, slides in the +Y-axis direction along the pair of left and right guide rails 62 together with the chuck table 10 and the like, so that the wafer 100 held on the holding surface 11 of the chuck table 10 is positioned below the grinding wheel 25 of the grinding mechanism 20. At this time, the horizontal positional relationship between the segment grinding wheel 252 and the lower surface (machining surface) 255 (see FIG. 3 ) of the segment grinding wheel 252 passes through the center of the wafer 100.

[0032] In addition, a motor (not shown) is driven to rotate the chuck table 10, thereby rotating the wafer 100 held on the holding surface 11 of the chuck table 10, and the spindle motor 23 is driven to rotate the grinding wheel 25.

[0033] As described above, while the wafer 100 and the grinding wheel 25 are rotating, the moving mechanism 30 is driven to lower the grinding wheel 25 in the −Z-axis direction. That is, when the motor 34 is driven to rotate the ball screw shaft 33, the lifting plate 31, which is provided with a nut member (not shown) that threadably fits onto the ball screw shaft 33, is lowered in the −Z-axis direction together with the housing 22 and the grinding wheel 25. As a result, the lower surface (machining surface) 256 (see FIG. 3 ) of the segmented grindstone 252 of the grinding wheel 25 comes into contact with the upper surface (back surface) of the wafer 100. When the grinding wheel 25 is further lowered a predetermined amount in the −Z-axis direction from the state in which the lower surface 256 of the segmented grindstone 252 is in contact with the upper surface of the wafer 100, the upper surface of the wafer 100 is ground by a predetermined amount by the segmented grindstone 252.

[0034] The above grinding process of the wafer 100 wears the segmented grindstone 252 of the grinding wheel 25, and the remaining amount thereof gradually decreases, but when this remaining amount decreases beyond a predetermined value, the grinding wheel 25 is replaced with a new one. In this embodiment, the remaining amount of the segmented grindstone 252 is calculated from the height position (first position) of the lower surface 256 of the segmented grindstone 252 and the height position (second position) of the lower surface 255 of the base 251, which are optically detected by the detection mechanism 40, and a method for calculating the remaining amount of the segmented grindstone 252 will be described below.

[0035] (How to calculate the remaining amount of segment grinding wheel) Figure 4 shows the relationship between the height position h of the grinding mechanism 20 and the output voltage V of the detection mechanism 40. Figure 4 shows the change in output voltage V corresponding to the amount of light received by the light-receiving unit 42 when the grinding wheel 25 is lowered and the segment grinding stone 252 and base 251 enter the gap 43 between the light-emitting unit 41 and the light-receiving unit 42 of the detection mechanism 40. In this case, the output voltage V is represented as the sum (integral value) of the output voltage values ​​when the grinding wheel 25 makes one rotation.

[0036] When the grinding wheel 25 is lowered, before the segment grindstone 252 enters the gap 43 between the light-projecting unit 41 and the light-receiving unit 42 of the detection mechanism 40, all of the light 411 emitted from the light-projecting unit 41 is received by the light-receiving unit 42, so the amount of light received by the light-receiving unit 42 is at its maximum, and the output voltage V of the detection mechanism 40 exhibits the maximum value Vmax shown in Fig. 4. Note that the light 411 received by the light-receiving unit 42 includes reflected light, but when the light-receiving unit 42 receives direct light that does not include this reflected light, the output voltage value Vs exhibits a value somewhat lower than the maximum value Vmax as shown in Fig. 4.

[0037] Then, as the grinding wheel 25 further descends and a part of the segment grindstone 252 enters the gap 43 between the light-projecting unit 41 and the light-receiving unit 42 of the detection mechanism 40 as shown in Figure 3(a), the light 411 emitted from the light-projecting unit 41 is intermittently blocked by the rotating segment grindstone 252, and the light 411 intermittently reaches and is received by the light-receiving unit 42. For this reason, the output voltage V from the detection mechanism 40 decreases linearly as the grinding wheel 25 descends (as the height position h of the grinding mechanism 20 increases).

[0038] 3(a), when the lower surface 256 of the segmented grindstone 252 is optically detected by the detection mechanism 30, that is, when the height position h of the grinding mechanism 20 reaches h1 shown in FIG. 4, the output voltage V at that time indicates V1 at point a shown in the figure, and the lower surface 256 of the segmented grindstone 252 is optically detected by the detection mechanism 40, a signal to that effect is sent from the detection mechanism 40 to the control unit 50. Then, the grindstone lower surface recognition unit 51 of the control unit 50 recognizes the height position h1 of the grinding mechanism 20 read from the scale 70 by the reading unit 71 at the timing when the signal is received as the height position (first position) of the lower surface 256 of the segmented grindstone 252.

[0039] Thereafter, as the grinding wheel 25 further descends, and as shown in FIG. 3(b), a portion of the base 251 enters the gap 43 between the light-projecting unit 41 and the light-receiving unit 42 of the detection mechanism 40, the light 411 emitted from the light-projecting unit 41 is completely blocked by the base 251, the amount of light received by the light-receiving unit 42 becomes zero, and as shown in FIG. 4, the output voltage V of the detection mechanism 40 also becomes zero at the illustrated point b. That is, when the height position h of the grinding mechanism 20 reaches h2 shown in FIG. 4, as shown in FIG. 3(b), the lower surface 255 of the base 251 is optically detected by the detection mechanism 40, and a signal to that effect is transmitted from the detection mechanism 40 to the control unit 50. Then, the base lower surface recognition unit 52 of the control unit 50 recognizes the height position h2 of the grinding mechanism 20, which is read from the scale 70 by the reading unit 71 at the time of receiving the signal, as the height position (second position) of the lower surface 255 of the base 251.

[0040] As described above, when the grinding wheel undersurface recognition unit 51 of the control unit 50 recognizes the height position (first position) h1 of the undersurface 256 of the segment grinding wheel 252 and the base undersurface recognition unit 52 recognizes the height position (second position) h2 of the undersurface 255 of the base 251, the remaining amount calculation unit 53 provided in the control unit 50 calculates the difference Δh (= h2 - h1) between the first position h1 and the second position h2 as the remaining amount of the segment grinding wheel 252.

[0041] (Effects of the present invention) As described above, in the grinding device 1 according to the present invention, the grinding mechanism 20 is lowered only once, and the height position (first position) h1 of the lower surface 256 of the segment grinding stone 252 of the grinding wheel 25 and the height position (second position) h2 of the lower surface 255 of the base 251 are optically recognized by the detection mechanism 40, and the difference Δh (= h2 - h1) between these height positions h1 and h2 is calculated as the remaining amount of the segment grinding stone 252, thereby achieving the effect of being able to accurately determine the remaining amount of the segment grinding stone 252 in a short period of time.

[0042] Although the above description has been given of an embodiment in which the present invention is applied to a wafer grinding machine, the present invention is also applicable to grinding machines that perform grinding processing on any workpiece other than wafers.

[0043] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0044] 1: Grinding device, 2: Base, 3: Inner base, 4: Base opening, 5: Cover, 6,7: Stretchable cover, 8: Column 10: chuck table, 11: holding surface of chuck table, 12: recessed portion of chuck table; 13: porous member; 20: grinding mechanism, 21: spindle, 22: housing, 23: spindle motor, 24: mount, 25: grinding wheel, 251: base, 255: underside of base, 252: Segment grinding wheel, 256: Lower surface of segment grinding wheel, 30: moving mechanism, 31: lifting plate, 32: guide rail, 321: guide groove, 33: ball screw shaft, 34: motor, 35: bracket, 36: encoder, 37: Bearing, 40: Detection mechanism, 41: Light-emitting unit, 42: Light-receiving unit, 43: Gap, 50: control unit, 51: grindstone bottom surface recognition unit, 52: base bottom surface recognition unit, 53: remaining amount calculation unit, 60: horizontal movement mechanism, 61: slider, 62: guide rail, 63: Ball screw shaft, 64: Motor, 65: Bearing 70: Scale, 71: Reading unit, 100: Wafer (workpiece), 411: light, h: height position of grinding mechanism, h1: first position, h2: second position, Δh: remaining amount of segment grinding wheel, V, V1: output voltage, Vmax: maximum output voltage, Vs: standard output voltage, 253: circumferential length of segment grinding wheel, 254: gap between segment grinding wheels

Claims

[Claim 1] a chuck table that holds the workpiece on a holding surface; a grinding mechanism that grinds the workpiece held on the holding surface with a plurality of segmented grindstones arranged annularly on a grinding wheel attached to a spindle; a moving mechanism having a position recognition unit that moves the grinding mechanism in a direction perpendicular to the holding surface and recognizes the height position of the grinding mechanism; A grinding device comprising: The grinding wheel is composed of an annular base attached to a mount connected to the tip of the spindle, and a plurality of segment grinding stones arranged in an annular shape with gaps between them on the underside of the base, a detection mechanism consisting of a light-emitting unit and a light-receiving unit that are arranged opposite to each other and spaced apart in the radial direction of the base so that the base of the grinding wheel moved by the moving mechanism can enter; a grinding wheel underside recognition unit that recognizes the underside of the segment grinding wheel based on the amount of light received by the light-receiving unit; a base underside recognition unit that recognizes the underside of the base based on the amount of light received by the light-receiving unit; and a remaining amount calculation unit that calculates the remaining amount of the segment grinding wheel, The remaining amount calculation unit lowers the grinding mechanism toward the detection mechanism using the moving mechanism, and calculates the remaining amount of the segment grinding wheel as the difference between a first position of the grinding mechanism recognized by the grinding wheel undersurface recognition unit when the grinding wheel undersurface recognition unit recognizes the undersurface of the segment grinding wheel of the rotating grinding wheel, and a second position of the grinding mechanism recognized by the base undersurface recognition unit when the grinding mechanism is lowered and the base undersurface recognition unit recognizes the undersurface of the base of the rotating grinding wheel.

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