JP2013251457A - Cutting blade tip position detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting blade tip position detection method capable of detecting a tip position of a cutting blade in a short period of time.SOLUTION: The cutting blade tip position detection method in a cutting device provided with a chuck table, cutting means with a cutting blade 21 attached thereto, cut feeding means, and a blade tip detection means includes a rough detection step for moving a cutting blade in a cut feeding direction from a first origin Z01 toward the blade tip detection means at a first velocity V1, decelerating to a second velocity V2 at a first velocity change position Z11, and making the cutting blade intrude between a light emitting part and a light receiving part of the blade tip detection means to detect the cutting blade, and a precise detection step for moving the cutting blade in a cut feeding direction from a second origin Z02 at a third velocity V3 after the rough detection step, further decelerating to a fourth velocity V4 at a second velocity change position Z12, and making the cutting blade go into between the light emitting part and the light receiving part of the blade tip detection means to detect the cutting blade.

Description

  The present invention relates to a cutting edge position detection method for a cutting blade in a cutting apparatus having a cutting blade for cutting a workpiece such as a semiconductor wafer held on a chuck table.

  Cutting along a street of a workpiece such as a semiconductor wafer or an optical device wafer is usually performed by a cutting device called a dicer. In this cutting apparatus, a cutting blade is cut to about 10 to 30 μm in a dicing tape to which a workpiece is fixed and completely cut into individual devices. However, if the amount of cutting into the dicing tape is not sufficient, the wafer is not suitable. It becomes a complete cut, and the lower cut edge is notched. In addition, the cutting blade used for cutting has a property of being consumed (abraded) as it is cut, and it is necessary to correct the cutting depth variation due to the consumption of the cutting blade as needed. Such variation in the cutting edge position of the cutting blade is detected at any time by a position detection means called an optical sensor, and the height position of the cutting blade is corrected (origin position correction) based on the detection result (Patent Document 1). reference). With this technique, it is possible to easily detect the height position of the cutting blade without damaging the cutting blade without cutting the chuck table for fixing the workpiece or the workpiece.

Japanese Patent Laid-Open No. 08-288244

  As a method for measuring the amount of wear of a cutting blade using this technique, the cutting blade is usually inserted between the light receiving and emitting portions of the optical sensor about two to three times, and the position where the predetermined amount of received light is detected is cut. Blade wear is measured. At this time, the cutting blade is gradually lowered from a predetermined origin height to approach the optical sensor. The slower the descent speed, the more accurate measurement is possible. However, since it takes more time to measure, it was usual to lower the cutting blade at a high speed to a moderate distance and then carry out the measurement at a slower speed. Moreover, since there is a possibility that the cutting fluid dripping from the cutting blade may be erroneously detected in one measurement, the measurement operation is performed a plurality of times. Therefore, it takes a time of several tens of seconds for one measurement, and in the case of machining that measures the consumption of the cutting blade at a relatively short interval, there is a disadvantage that the measurement time is very long.

  An object of the present invention is to provide a cutting edge position detection method for a cutting blade that can detect the cutting edge position of the cutting blade in a short time.

  The cutting blade edge position detection method of the present invention includes a chuck table for holding a workpiece on a holding surface, and a cutting means including a spindle on which a cutting blade for cutting the workpiece held on the holding surface is mounted. A cutting feed means for moving the cutting means in the cutting feed direction with respect to the chuck table; and a blade edge detection means for detecting a tip position of the cutting blade in the cutting feed direction having a light emitting portion and a light receiving portion; A cutting edge position detecting method of the cutting blade in a cutting apparatus comprising: a cutting blade moving the cutting blade in a cutting feed direction at a first speed from a first origin toward the cutting edge detection means; Decelerating to a second speed at the speed change position, causing the cutting blade to enter between the light emitting part and the light receiving part of the blade edge detecting means, and blocking a predetermined amount of light from the light emitting part. A rough detection step for detecting the tip position of the cutting blade, and a position near the blade edge detection means between the first speed change position and the blade edge detection means after the rough detection step; and From the second origin where the cutting blade does not block the light beam from the light emitting portion, the cutting blade is moved in the cutting feed direction at a third speed lower than the first speed, and in the rough detection step And further decelerating to a fourth speed at a second speed change position that is further away from the second origin than the detection error range with respect to the detection position, and the light emitting part and the light receiving part of the blade edge detecting means And a precision detection step of detecting the tip position of the cutting blade by blocking the light beam from the light emitting portion by a predetermined amount.

  In the cutting edge position detection method of the cutting blade, it is preferable that the second origin is located at an end portion on the cutting edge detection means side in a range where the cutting blade does not block light from the light emitting portion.

  According to the cutting edge position detection method for a cutting blade according to the present invention, the cutting edge position of the cutting blade can be detected in a short time.

FIG. 1 is a perspective view illustrating a configuration of a cutting apparatus according to an embodiment. FIG. 2 is an enlarged view of the blade edge detecting means. FIG. 3 is a block diagram of the cutting apparatus according to the embodiment. FIG. 4 is an explanatory diagram of the reference voltage. FIG. 5 is an explanatory diagram of a cutting edge position detection method for a cutting blade according to the embodiment. FIG. 6 is a view showing a cutting blade having a thin blade thickness. FIG. 7 is a diagram showing a cutting blade having a large blade thickness.

  Hereinafter, a cutting edge position detection method for a cutting blade according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment]
The embodiment will be described with reference to FIGS. 1 to 7. The present embodiment relates to a cutting edge position detection method for a cutting blade. 1 is a perspective view showing a configuration of a cutting device 1 according to an embodiment of the present invention, FIG. 2 is an enlarged view of a blade edge detecting means 80, FIG. 3 is a block diagram of the cutting device 1 according to the embodiment, and FIG. FIG. 5 is an explanatory diagram of a reference voltage, FIG. 5 is an explanatory diagram of a cutting edge position detection method of a cutting blade according to the embodiment, FIG. 6 is a diagram showing a cutting blade 21 with a thin blade thickness, and FIG. 7 is a thick blade thickness. It is a figure which shows the cutting blade.

  A cutting apparatus 1 shown in FIG. 1 cuts a workpiece by relatively moving a cutting means 20 having a cutting blade 21 and a chuck table 10 holding a workpiece (not shown). . The cutting apparatus 1 according to this embodiment is a dicer having one spindle, but may be a dicer having two spindles, a so-called dual dicer (for example, a facing dual dicer or a parallel dual dicer). The cutting apparatus 1 includes a chuck table 10, a cutting unit 20, an X-axis moving unit 40, a Y-axis moving unit 50, a Z-axis moving unit 60, a θ-axis rotating unit 70, a blade edge detecting unit 80, and an imaging. And means 30.

  The chuck table 10 holds a workpiece on the upper surface. The chuck table 10 has a holding part 11. The holding unit 11 holds the workpiece on the holding surface 11a (front surface) by sucking the workpiece from the back surface. The portion constituting the holding surface 11a of the holding portion 11 has a disc shape made of porous ceramic or the like, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The workpiece is a workpiece to be processed by the cutting apparatus 1, and is, for example, a semiconductor wafer or an optical device wafer.

  The cutting means 20 is mounted on the cutting blade moving base 8 via the wall portion 5 and the support portion 4. The cutting means 20 includes a cutting blade 21, a spindle 22, a spindle housing 23, and a cutting fluid supply nozzle 24. The cutting means 20 performs processing while supplying a cutting fluid to the workpiece held on the chuck table 10. At this time, the cutting unit 20 processes the region to be processed of the workpiece with the cutting blade 21 based on the image data of the workpiece imaged by the imaging unit 30.

  The cutting blade 21 cuts the workpiece held on the holding surface 11 a of the chuck table 10. The cutting blade 21 is an extremely thin cutting grindstone having a substantially ring shape. The cutting blade 21 is detachably attached to one end of the spindle 22. The cutting fluid supply nozzle 24 supplies the cutting fluid to a processing point of the workpiece during processing of the workpiece by the cutting blade 21.

  The Y-axis moving unit 50 corresponds to an index feeding unit that relatively moves the workpiece held on the chuck table 10 and the cutting blade 21 in the Y-axis direction shown in FIG. The Y-axis direction is the direction of the rotation axis of the cutting blade 21 and is orthogonal to the vertical direction. The Y-axis moving means 50 includes a Y-axis pulse motor 51, a Y-axis ball screw 52, a pair of Y-axis guide rails 53, 53, a Y-axis position detection scale 54, and a Y-axis position detection sensor 55. Contains. The Y-axis moving means 50 moves the cutting blade moving base 8 in the Y-axis direction with respect to the apparatus main body 3 by rotationally driving the Y-axis ball screw 52 by the rotational force generated by the Y-axis pulse motor 51.

  The X-axis direction is orthogonal to the index feed direction and the vertical direction. The X-axis moving unit 40 corresponds to a cutting feed unit that moves the workpiece held on the chuck table 10 relative to the cutting blade 21 in the X-axis direction. The X-axis moving means 40 includes an X-axis pulse motor 41, an X-axis ball screw 42, a pair of X-axis guide rails 43, 43, an X-axis position detection scale 44, and an X-axis position detection sensor 45. Contains. The X-axis moving means 40 rotates and drives the X-axis ball screw 42 by the rotational force generated by the X-axis pulse motor 41, so that the table moving base 2 (chuck table 10) is paired with a pair of X-axis guide rails 43 and 43. And moving in the X-axis direction with respect to the apparatus main body 3 while guiding.

  The Z-axis moving unit 60 corresponds to a cutting feed unit that moves the cutting blade 21 relative to the workpiece held on the chuck table 10 in the Z-axis direction, that is, the direction in which the spindle 22 approaches and separates from the chuck table 10. . The Z-axis direction of this embodiment is a vertical direction. The Z-axis moving means 60 is provided on the cutting blade moving base 8 and includes a Z-axis ball screw 61, a Z-axis pulse motor 62, and a pair of Z-axis guide rails 63. The Z-axis moving means 60 rotates the Z-axis ball screw 61 by the rotational force generated by the Z-axis pulse motor 62, thereby guiding the support portion 4 with the pair of Z-axis guide rails 63 and the apparatus body 3. Move relative to the Z-axis.

  The Z-axis moving unit 60 includes a Z-axis position detection mechanism that detects the position of the cutting unit 20 in the Z-axis direction. The Z-axis position detection mechanism includes, for example, a Z-axis position detection scale and a Z-axis position detection sensor.

  The θ-axis rotating means 70 includes a θ-axis rotating motor 71 and a table 72. The table 72 mounts the chuck table 10 and is supported on the table moving base 2 via a θ-axis rotation motor 71 so that the table 72 can rotate around the central axis of the chuck table 10. The table 72 can cause the chuck table 10 to rotate at an arbitrary angular rotation or continuous rotation with respect to the cutting blade 21 about the central axis thereof.

  The imaging means 30 is composed of a plurality of pixels, images the workpiece held on the chuck table 10, and generates an image. The imaging unit 30 is, for example, a camera using a CCD (Charge Coupled Device) image sensor, but is not limited thereto.

  The control means 6 is an electronic control device having a computer. The control means 6 is connected to the X-axis moving means 40, the Y-axis moving means 50, the Z-axis moving means 60, and the θ-axis rotating means 70, respectively, and controls each means 40, 50, 60, 70.

(Blade position detection device)
Here, the blade edge position detection apparatus that executes the blade edge position detection method of the cutting blade according to the present embodiment will be described. The blade edge position detection device includes a blade edge detection unit 80, a Z-axis movement unit 60, and a control unit 6.

  As shown in FIG. 1, the cutting apparatus 1 has a blade edge detection means 80. The blade edge detection means 80 detects the tip position (lower end position) of the cutting blade 21 in the cutting feed direction. The blade edge detection means 80 is disposed in the vicinity of the chuck table 10, for example, on the moving table 73 that holds the chuck table 10. The blade edge detection means 80 is arranged at the corner of the upper surface of the moving table 73, in this embodiment, at the corner that is the end in the + X direction and the end in the -Y direction.

  As illustrated in FIG. 2, the blade edge detection unit 80 includes a light emitting unit 81, a light receiving unit 82, and a support member 83. The support member 83 is fixed to the upper surface of the moving table 73. The support member 83 includes a first protrusion 83a and a second protrusion 83b that protrude vertically upward, that is, in the + Z-axis direction. The first protrusion 83a and the second protrusion 83b face each other with a gap in the Y-axis direction. A gap between the first protrusion 83a and the second protrusion 83b is a blade intrusion portion 86 into which the cutting blade 21 can enter. The blade intrusion portion 86 is a substantially U-shaped space, and has a width that allows at least the cutting blade 21 having the maximum blade thickness that can be used by the cutting means 20 to enter. The bottom of the blade intrusion portion 86 has an inclination that goes downward in the vertical direction as it goes in the −X direction.

  The light emitting part 81 is provided in the first protrusion 83a. The light receiving part 82 is provided in the second protrusion 83b. The light emitting unit 81 and the light receiving unit 82 are arranged to face each other in the Y-axis direction. The light emitting unit 81 includes, for example, a light emitting element as a light source 87 (see FIG. 3), and irradiates light toward the light receiving unit 82. For example, the light receiving unit 82 includes a light receiving element.

  The support member 83 is provided with an air supply nozzle 84 and a cleaning water supply nozzle 85. The cleaning water supply nozzle 85 supplies cleaning water to the cutting blade 21 that has entered the blade intrusion portion 86 and cleans the cutting blade 21. The air supply nozzle 84 supplies air to the cutting blade 21 that has entered the blade intrusion portion 86, and blows away cleaning water to dry the cutting blade 21.

  The control means 6 has a function of executing the cutting edge position detection method of the cutting blade according to the present embodiment. As illustrated in FIG. 3, the control unit 6 includes a photoelectric conversion unit 31, a reference voltage setting unit 32, a voltage comparison unit 33, an end position detection unit 34, a calculation unit 35, and a position correction unit 36. .

  The light emitting unit 81 irradiates light generated by the light source 87 toward the light receiving unit 82. The photoelectric conversion unit 31 converts the amount of light received by the light receiving unit 82 into a voltage and outputs the voltage. The photoelectric conversion unit 31 outputs a voltage corresponding to the amount of light received by the light receiving unit 82. When the amount of received light is large, the photoelectric conversion unit 31 outputs a higher voltage than when the amount of received light is small.

  The reference voltage setting unit 32 sets and outputs a reference voltage. As shown in FIG. 4, a reference voltage is set in advance for the output voltage of the photoelectric conversion unit 31. The reference voltage is a voltage lower than the maximum voltage output from the photoelectric conversion unit 31. For example, the reference voltage when the maximum voltage is 5V can be 3V.

  The voltage comparison unit 33 compares the output voltage of the photoelectric conversion unit 31 with the reference voltage output by the reference voltage setting unit 32, and outputs a comparison result signal. For example, the voltage comparison unit 33 outputs different signals depending on whether the output voltage of the photoelectric conversion unit 31 is higher than the reference voltage or lower than the reference voltage.

  The end position detector 34 detects the cutting edge position (end position) of the cutting blade 21 based on the signal output from the voltage comparator 33 and the signal acquired from the Z-axis moving means 60. The control unit 6 detects the cutting edge position of the cutting blade 21 by lowering the cutting blade 21 to enter the blade intrusion portion 86 and blocking the light beam from the light emitting portion 81. Here, the blade edge position is a position in the Z-axis direction of the cutting means 20 when it is determined that the light beam is blocked by the cutting blade 21. The end position detection unit 34 acquires a signal indicating the Z axis position of the cutting means 20 from the Z axis position detection mechanism. The end position detection unit 34 detects the Z of the cutting means 20 when the signal output from the voltage comparison unit 33 when the cutting blade 21 is lowered to enter the blade intrusion unit 86 becomes a signal indicating a reference voltage or less. The shaft position is detected as the cutting edge position of the cutting blade 21.

  The calculation unit 35 calculates a correction amount of the position of the cutting blade 21 in the cutting feed direction based on the end position detected by the end position detection unit 34. Further, the calculation unit 35 may calculate the wear amount of the cutting blade 21 based on a change in the cutting edge position of the cutting blade 21.

  The position correction unit 36 corrects the position of the cutting blade 21 in the cutting feed direction based on the correction amount and the wear amount calculated by the calculation unit 35. Based on the position of the cutting blade 21 corrected by the position correction unit 36, the position of the cutting blade 21 when processing the workpiece is controlled.

(Cutting blade edge position detection method)
Next, a cutting edge position detection method for a cutting blade according to this embodiment will be described. In the cutting apparatus 1, setup for detecting the cutting edge position of the cutting blade 21 is executed as appropriate. The setup is executed, for example, when the cutting blade 21 is replaced or whenever a predetermined number of workpieces are cut.

  The cutting edge position detection method for a cutting blade according to this embodiment includes a chuck table 10 that holds a workpiece on a holding surface 11a and a spindle on which a cutting blade 21 that cuts the workpiece held on the holding surface 11a is mounted. 22, a cutting means 20 including a cutting blade 20, a cutting feed means (Z-axis moving means 60) that moves the cutting means 20 in the cutting feed direction with respect to the chuck table 10, a light emitting portion 81, and a light receiving portion 82. A cutting edge position detection method for a cutting blade in the cutting apparatus 1 provided with a cutting edge detection means 80 for detecting the tip position in the cutting and feeding direction, and includes a rough detection process and a precision detection process.

  The cutting edge position detection method of the cutting blade according to the present embodiment performs rough detection in the rough detection process, performs high precision detection in the precision detection process, and further positions each origin position and speed change position at that time individually. This enables accurate measurement in a short time. Each detection process will be described with reference to FIG. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the distance in the cutting feed direction from the blade edge detection means 80. In addition, the distance from the blade edge | tip detection means 80 can be based on the position of the light emission part 81, for example.

(Coarse detection process)
In the rough detection step, the cutting blade 21 is moved from the first origin Z01 toward the cutting edge detection means 80 in the cutting feed direction (−Z direction) at a high first speed V1, and at the first speed change position Z11. The tip of the cutting blade 21 is decelerated to the second speed V2, the cutting blade 21 is inserted between the light emitting portion 81 and the light receiving portion 82 of the blade edge detecting means 80, and a predetermined amount of light from the light emitting portion 81 is blocked. This is a step of detecting the position.

  In the rough detection step, the control means 6 moves the cutting blade 21 in the cutting feed direction at a first speed V1 from a predetermined first origin Z01 toward the blade edge detection means 80. The control means 6 previously adjusts the X-axis position and the Y-axis position of the cutting means 20 so that the blade intrusion portion 86 (the optical axis of the light emitting portion 81) of the blade edge detection means 80 is located directly below the cutting edge of the cutting blade 21. Then, the cutting means 20 is lowered. The first origin Z01 is, for example, the origin position of the Z-axis moving means 60, and the cutting blade 21 does not contact the workpiece or the like even if the cutting means 20 is moved in the X-axis direction or the Y-axis direction. Is the height position.

  The first speed V1 is a maximum speed generated by the Z-axis moving unit 60, for example. By setting the first speed V1 to a high speed, the time required for detecting the cutting edge position of the cutting blade 21 can be shortened. The second speed V2 is lower than the first speed V1, for example, a speed at which the Z-axis pulse motor 62 cannot step out, in other words, even if the Z-axis moving means 60 is suddenly stopped, The speed at which the motor 62 does not step out. The second speed V2 is, for example, the maximum speed in a speed range where the step-out of the Z-axis pulse motor 62 cannot occur.

  The first speed change position Z11 is a position away from the blade edge detection means 80 by a predetermined distance in the Z-axis direction. The predetermined distance is a distance obtained by adding a margin to the distance (stop distance) in the cutting feed direction necessary for stopping the cutting means 20 by the brake means. When the Z-axis pulse motor 62 is stepped out while the cutting device 20 is moved by the Z-axis moving device 60, the cutting device 1 stops the cutting device 20 by the mechanical brake device. The stopping distance is determined by the cutting means 20 until the cutting means 20 is stopped by operating the brake means when the Z-axis pulse motor 62 steps out when the cutting means 20 is lowered at the first speed V1. It is the distance that moves. The stop distance is determined so that the cutting means 20 can be stopped by the brake means without bringing the cutting means 20 into contact with the blade edge detection means 80. The stop distance is desirably determined so that the cutting means 20 is not brought into contact with the blade edge detection means 80 even when the cutting blade 21 having the maximum diameter that can be used by the cutting means 20 is mounted.

  The control means 6 decelerates the moving speed of the cutting means 20 in the Z-axis direction from the first speed V1 to the second speed V2 at the first speed change position Z11, and emits the cutting blade 21 at the second speed V2. It penetrates between the part 81 and the light receiving part 82. Here, intrusion of the cutting blade 21 between the light emitting unit 81 and the light receiving unit 82 not only blocks the region that linearly connects the light emitting unit 81 and the light receiving unit 82 with the cutting blade 21 but also enters the blade. It also includes causing the cutting blade 21 to enter the portion 86 and causing the cutting blade 21 to enter a region that blocks the light beam from the light emitting portion 81.

  When the cutting blade 21 blocks a predetermined amount of light from the light emitting unit 81, the output voltage of the photoelectric conversion unit 31 becomes equal to or lower than the reference voltage, and the control unit 6 determines that the cutting edge of the cutting blade 21 is detected by the cutting edge detection unit 80. The point Z21 in FIG. 5 is a detection position of the cutting edge of the cutting blade 21 detected in the rough detection process (hereinafter simply referred to as “detection position Z21 in the rough detection process”).

(Precise detection preparation process)
When the control means 6 detects the tip position of the cutting blade 21 in the rough detection process, the control means 6 executes a precision detection preparation process. In the precision detection preparation step, the cutting blade 21 is moved (raised) in the cutting feed direction in a direction away from the blade edge detection means 80 to the second origin Z02. The moving speed of the cutting blade 21 at this time is, for example, the first speed V1. When the cutting blade 21 is raised, a command such as a sudden stop or a reversal of the moving direction that causes a step-out of the Z-axis pulse motor 62 is not made. The time for detecting the tip position of the cutting blade 21 can be shortened by raising the cutting blade 21 at the first maximum speed V1.

  The second origin Z02 is a position closer to the blade edge detection means 80 than the first speed change position Z11, and the cutting blade 21 does not block the light beam from the light emitting portion 81 regardless of the blade thickness of the cutting blade 21 or the like. The position in the Z-axis direction. The position of the cutting blade 21 shown in FIG. 6 in the Z-axis direction and the position of the cutting blade 21 shown in FIG. 7 in the Z-axis direction are the same. Even if the cutting blade 21 with a thin blade thickness does not block the light beam 88 as shown in FIG. 6, the cutting blade 21 with a thick blade thickness may block the light beam 88 as shown in FIG. As shown in FIG. 7, the reflected light 89 reflected by the cutting blade 21 may enter the light receiving unit 82 and affect the detection result of the blade edge position. The second origin Z02 is preferably a position that does not block the light beam 88 even if the cutting blade 21 has a thick blade thickness and is close to the blade edge detection means 80. The second origin Z02 is a position near the blade edge detection means 80 between the first speed change position Z11 and the blade edge detection means 80, and is a position where the cutting blade 21 does not block the light beam from the light emitting portion 81. Preferably there is. The second origin Z02 is located, for example, between the blade edge detection means 80 and the first speed change position Z11 and at the edge on the blade edge detection means 80 side in a range where the cutting blade 21 does not block the light beam 88. Can be.

  By raising the cutting blade 21 to the second origin Z02 after the execution of the rough detection process, the next precision detection process can be started in a state where the cutting blade 21 does not block the light beam 88. For example, when the cutting blade 21 is lowered, the second origin Z02 is a position in the Z-axis direction where the cutting blade 21 having the maximum usable blade thickness starts to block the light beam 88 (hereinafter referred to as a “cutting start position”). .)) On the + Z side. As an example, the second origin Z02 is a position on the + Z side by a predetermined distance from the cutoff start position. From the viewpoint of shortening the time for detecting the tip position of the cutting blade 21, it is preferable that the second origin Z02 is as close to the −Z side as possible, that is, close to the blade edge detection means 80. As an example, the second origin Z02 may be a position on the + Z side from the cutoff start position by a distance corresponding to the positioning accuracy of the Z-axis moving unit 60.

(Precise detection process)
The precision detection process is performed after the coarse detection process. In the present embodiment, the precision detection process is executed after the precision detection preparation process. In the precision detection process, the cutting blade 21 is moved from the second origin Z02 toward the cutting edge detection means 80 in the cutting feed direction at a third speed V3 that is lower than the first speed V1. The light-emitting part 81 and the light-receiving part 82 of the blade edge detecting means 80 are further decelerated to the fourth speed V4 at the second speed change position Z12 that is separated from the detection error range closer to the second origin Z02 than the detection error range. Is a step of detecting the tip position of the cutting blade 21 by allowing the cutting blade 21 to enter between the two and blocking a predetermined amount of light from the light emitting portion 81.

  First, the control means 6 moves the cutting blade 21 from the second origin Z02 to the second speed change position Z12 toward the cutting edge detection means 80 at the third speed V3 in the cutting feed direction. The control means 6 reduces the moving speed of the cutting blade 21 to the fourth speed V4 at the second speed change position Z12. The second speed change position Z12 is a position separated from the detection position Z21 in the coarse detection process closer to the second origin Z02 than the detection error range in the coarse detection process. The detection error when detecting the cutting edge position of the cutting blade 21 depends on the accuracy of the detection circuit, the moving speed of the cutting blade 21 in the cutting feed direction, and the like. When the detection error is ± α (α is positive) for the detection position Z21 in the rough detection process, the second speed change position Z12 is closer to the second origin Z02 by α than the detection position Z21 in the rough detection process. It is a position on the second origin Z02 side from the position of.

  From the viewpoint of shortening the time for detecting the tip position of the cutting blade 21, it is preferable that the second speed change position Z12 is as close to the −Z side as possible, that is, a position close to the blade edge detection means 80. . As an example, the second speed change position Z12 may be a position on the + Z side of the detection error range by a distance corresponding to the positioning accuracy of the Z-axis moving unit 60. The second speed change position Z12 may be a position where the cutting blade 21 is in a state where the light beam 88 from the light emitting unit 81 is blocked.

  The third speed V3 is lower than the first speed V1, and is, for example, a speed at which the Z-axis pulse motor 62 cannot step out, in other words, even if the Z-axis moving means 60 is suddenly stopped. The speed at which the motor 62 does not step out. The third speed V3 may be higher than the second speed V2, may be lower than the second speed V2, or may be the same as the second speed V2. The third speed V3 is, for example, the maximum speed in a speed range where the step-out of the Z-axis pulse motor 62 cannot occur.

  The fourth speed V4 is lower than the third speed V3. The fourth speed V4 is, for example, a very low speed that allows precise detection of the cutting edge position of the cutting blade 21. The fourth speed V4 can be determined based on the detection accuracy allowed in the detection of the cutting edge position of the cutting blade 21. When the cutting blade 21 enters between the light emitting portion 81 and the light receiving portion 82 at a low fourth speed V4, a position (cutting edge position) where the cutting blade 21 blocks a predetermined amount of the light beam 88 from the light emitting portion 81 is obtained. It can be detected accurately and precisely. A point Z22 in FIG. 5 is a detection position of the cutting edge of the cutting blade 21 detected in the precision detection process (hereinafter simply referred to as “detection position Z22 in the precision detection process”). When the cutting edge position of the cutting blade 21 is detected, the precision detection process ends. The detection position Z22 in the precision detection process is handled as the cutting edge position of the latest cutting blade 21. The calculation unit 35 calculates the correction amount of the position of the cutting blade 21 in the cutting feed direction based on the detection position Z22 in the precision detection process.

(Comparison process)
A comparison step may be performed after the precision detection step. The comparison step is a step of comparing the detection position Z21 in the rough detection step with the detection position Z22 in the precise detection step. When the difference between the Z coordinate of the detection position Z21 in the rough detection process and the Z coordinate of the detection position Z22 in the precision detection process is greater than or equal to a predetermined value, the control means 6 determines that the detection is erroneous. When it is determined that there is an erroneous detection, the control unit 6 resets all the detection positions Z21 and Z22, and executes the detection of the cutting edge position of the cutting blade 21 again from the rough detection process. Instead of this, the detection position Z21 in the rough detection process is made valid and the process is repeated after the execution of the rough detection process. When it is determined again that the detection is erroneous, the process returns to the rough detection process and the cutting edge of the cutting blade 21 again. The position detection may be performed again.

(Confirmation process)
In this embodiment, a confirmation process is further performed. The confirmation process is performed after the precision detection process. When the comparison process is performed, the confirmation process is performed after the comparison process when no erroneous detection is determined. In the confirmation step, the position of the cutting edge of the cutting blade 21 is further detected, and the presence or absence of erroneous detection is determined based on the detection result and the detection result in the precision detection step.

  The control means 6 detects the cutting edge position of the cutting blade 21 in the confirmation step. The detection procedure of the blade edge position at this time can be the same as the detection procedure in the precision detection process. The control means 6 uses the Z coordinate of the detection position of the tooth tip of the cutting blade 21 detected in the confirmation process (hereinafter simply referred to as “detection position in the confirmation process”) as the Z of the detection position Z22 in the precision detection process. When it has changed beyond a predetermined range as compared with the coordinates, it is determined as a detection error (false detection). When it is determined that there is an erroneous detection in the confirmation process, all the detection positions are reset and the cutting edge position of the cutting blade 21 is detected again from the rough detection process. Instead of this, the detection position Z21 in the coarse detection process is made valid and the process is repeated after the execution of the coarse detection process. When it is determined that the detection is erroneous again, the cutting edge position of the cutting blade 21 is detected from the coarse detection process. You may make it re-execute. Alternatively, only the detection position in the confirmation process may be invalidated, the confirmation process may be performed again, and the detection of the cutting edge position of the cutting blade 21 may be performed again from the rough detection process when it is determined again as an erroneous detection.

[Modification of Embodiment]
In the above embodiment, the first speed V1 is the maximum speed generated by the Z-axis moving unit 60, but is not limited to this. The first speed V1 can be appropriately determined within a speed range that can be generated by the Z-axis moving unit 60. In order to shorten the setup time, it is desirable that the first speed V1 is set to a higher speed within a range in which the Z-axis moving means 60 can be generated.

  The contents disclosed in the above embodiments can be executed in appropriate combination.

DESCRIPTION OF SYMBOLS 1 Cutting device 10 Chuck table 11 Holding part 11a Holding surface 20 Cutting means 21 Cutting blade 22 Spindle 60 Z-axis moving means 80 Cutting edge detection means 81 Light emitting part 82 Light receiving part 83 Support member 86 Blade intrusion part 88 Light beam V1 First speed V2 Second speed V3 Third speed V4 Fourth speed Z01 First origin Z02 Second origin Z11 First speed change position Z12 Second speed change position Z21 Detection position in coarse detection process Z22 Precision detection process Detection position at

Claims (2)

A chuck table for holding a workpiece on a holding surface, a cutting means including a spindle mounted with a cutting blade for cutting the workpiece held on the holding surface, and cutting the cutting means with respect to the chuck table The cutting edge of the cutting blade in a cutting apparatus comprising: a cutting feed means that moves in a feeding direction; and a blade edge detecting means that has a light emitting portion and a light receiving portion and detects a tip position of the cutting blade in the cutting feed direction. A position detection method,
The cutting blade is moved from the first origin toward the cutting edge detection means in the cutting feed direction at a first speed, decelerated to a second speed at a first speed change position, and the cutting edge detection means A rough detection step of detecting the tip position of the cutting blade by allowing the cutting blade to enter between the light emitting portion and the light receiving portion and blocking a predetermined amount of light from the light emitting portion;
After the rough detection step, a second position close to the blade edge detection means between the first speed change position and the blade edge detection means, and the cutting blade does not block light from the light emitting portion. The cutting blade is moved in the cutting feed direction at a third speed that is lower than the first speed from the origin of the second, and the second position is larger than the detection error range with respect to the detection position in the rough detection process. The speed is further reduced to the fourth speed at the second speed change position separated from the origin, and the cutting blade enters between the light emitting part and the light receiving part of the blade edge detecting means, A precision detection step of detecting the tip position of the cutting blade by blocking a predetermined amount of light; and
A cutting edge position detection method for a cutting blade, comprising:   2. The cutting edge position detection method for a cutting blade according to claim 1, wherein the second origin is located at an end on the cutting edge detection means side in a range in which the cutting blade does not block light from the light emitting portion.

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