Grinding Equipment

Abstract

To constitute a grinding device at low cost.SOLUTION: Segment grindstones 360 are detected using tip detecting means 5 and the number of the segment grindstones 360 or the like is counted using a counter 60, while rotating a grinding wheel 36 at a low speed (for instance 10 rpm) by jetting air through an air nozzle 7 provided in a grinding device 1 that grinds a work-piece 14. Further, a counted value counted using the counter 60 is compared with the number of the segment grindstones 360 memorized in advance in a determining part 61, so as to determine whether or not the segment grindstones 360 have dropped off. The grinding stone 1 is not required to comprise a motor or the like for rotating the grinding wheel 36 at a low speed, which enables the grinding device 1 to be configured at low cost.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a grinding device. [Background technology]

[0002] As disclosed in Patent Document 1, a grinding wheel mounted on a grinding device for grinding a workpiece includes a base and a plurality of segment grindstones arranged in an annular shape on the base with gaps therebetween. When grinding a workpiece, the grinding wheel is rotated and the chuck table on which the workpiece is held is rotated, causing the segment grinding wheel to advance from the outer periphery of the workpiece toward the center. When the segment grinding wheel enters the workpiece from the outer periphery, the segment grinding wheel may fall off the base due to the impact it receives.

[0003] If a grinding wheel has a portion where a segment grinding stone has fallen off, the surface to be ground will have an arc-shaped pattern in the unground portion, resulting in thickness differences in the patterned portions. Therefore, as disclosed in Patent Document 2, there is an invention for detecting the falling off of a segment grindstone. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-089065 A [Patent Document 2] JP 2017-127936 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, to detect the falling off of the segment grinding wheel, it is necessary to rotate the grinding wheel at a low speed of about 10 rpm. Rotating the grinding wheel at a low speed requires an encoder that detects the rotation angle of the rotating shaft, a servo motor that rotates the shaft while feeding back the rotation angle detected by the encoder, and a control unit that rotates the servo motor at a specified rotation angle, which are expensive. Therefore, the grinding device has a problem of being able to detect the falling off of the segment grinding wheel by rotating the grinding wheel at a low speed without being equipped with an expensive motor unit. [Means for solving the problem]

[0006] The present invention provides a grinding device comprising: a holding means for holding a workpiece on a holding surface; a grinding means having a rotatable grinding wheel with a plurality of segment grindstones arranged on a base in an annular shape with gaps provided therebetween, the grinding means using the segment grindstone to grind the workpiece held by the holding means; a grinding feed means for moving the grinding means in a direction perpendicular to the holding surface; and a tip detection means for detecting whether or not the segment grindstone is present, the tip detection means including an air nozzle for injecting air onto the grinding wheel positioned so that the tip detection means can detect the tip of the segment grindstone, and for rotating the grinding wheel at a speed detectable by the tip detection means; and a grinding wheel rotating by the air injected from the air nozzle. The tip end detected by the tip end detection means The grinding device is provided with a counter that counts the number of the segment grindstones or the number of the gaps, and a judgment unit that judges whether the segment grindstone has fallen off based on the value of the counter. The tip detection means provided in the grinding device includes a light-projecting section which projects measurement light, a light-receiving section which is disposed opposite the light-projecting section so that the segment grindstone can enter between the light-projecting section and receives the measurement light projected from the light-projecting section, and a detection section which detects the segment grindstone or the gap by a change in the amount of light received by the light-receiving section due to the segment grindstone entering between the light-projecting section and the light-receiving section, and the air nozzle includes a light-projecting section air injection section which blows air onto the light-projecting section, and a light-receiving section air injection section which injects air onto the light-receiving section, and the light-projecting section air injection section and the light-receiving section air injection section are arranged so that the direction of the air ejected from each section is neither parallel nor perpendicular to the tangent direction of the rotation orbit of the segment grindstone at the position where the air hits. The grinding wheel is rotated, and water droplets adhering between the light projecting unit and the light receiving unit are removed. It is desirable. Effect of the Invention

[0007] According to the present invention, the grinding wheel can be rotated at a low speed by blowing air, without the need for a special motor or the like for rotating the grinding wheel at a low speed. Therefore, an inexpensive grinding device that can detect the falling off of a segment grinding wheel can be constructed, which is economical. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view illustrating an entire grinding device. [Diagram 2] FIG. 2 is a bottom view of the first grinding wheel. [Diagram 3] 11 is a front view showing a state in which light projected from a light-projecting unit passes through a gap. FIG. [Figure 4] 10 is a graph showing a change in voltage when the grinding wheel intermittently blocks the measurement light from the light projector. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1. Grinding Equipment Configuration 1 is a grinding apparatus that grinds a workpiece 14 using grinding means 3. The configuration of the grinding apparatus 1 will be described below.

[0010] As shown in FIG. 1, the grinding device 1 includes a base 10 extending in the Y-axis direction, and a column 11 standing on the base 10 on the +Y direction side.

[0011] A grinding feed means 4 supporting the grinding means 3 is disposed on the side surface of the column 11 on the -Y direction side. The grinding means 3 includes a spindle 30 having a rotation axis 35 in the Z-axis direction, a housing 31 rotatably supporting the spindle 30, a motor 32 that rotates and drives the spindle 30 around the rotation axis 35, a mount 33 connected to the lower end of the spindle 30, and a grinding wheel 36 attached to the lower surface of the mount 33. The grinding wheel 36 is detachable from the mount 33, and another type of grinding wheel can be attached to the mount 33 instead of the grinding wheel 36.

[0012] The grinding wheel 36 includes a base 361 and a plurality of segment grindstones 360, each having a substantially rectangular parallelepiped shape, which are arranged in an annular shape on the lower surface of the base 361.

[0013] 2, two adjacent segment grindstones 360 are disposed with a gap 363 therebetween, and all of the segment grindstones 360 are arranged in a ring shape as a whole. Each segment grindstone 360 ​​has a segment length 364 as its length in the circumferential direction. A lower surface 362 of the segment grindstone 360 ​​serves as a grinding surface for grinding the workpiece 14.

[0014] By using the motor 32 shown in Figure 1 to rotate the spindle 30 around the rotation axis 35, the mount 33 connected to the spindle 30 and the grinding wheel 36 attached to the mount 33 rotate around the rotation axis 35 in the Z-axis direction that passes through the center of the base 361.

[0015] The grinding feed means 4 includes a ball screw 40 having a rotating shaft 45 in the Z-axis direction, a pair of guide rails 41 arranged parallel to the ball screw 40, a Z-axis motor 42 connected to the upper end of the ball screw 40 and rotating the ball screw 40 around the rotating shaft 45, a lifting plate 43 whose internal nut is screwed onto the ball screw 40 and whose side is in sliding contact with the guide rail 41, and a holder 44 connected to the lifting plate 43 and holding the spindle 30. By driving the ball screw 40 using the Z-axis motor 42, the ball screw 40 rotates around the rotation shaft 45, and the lifting plate 43 moves up and down in the Z-axis direction while being guided by the guide rail 41. As a result, the grinding means 3 held by the holder 44 moves in a direction perpendicular to the holding surface 200 (the Z-axis direction).

[0016] The holding means 2 is disposed on the base 10. The holding means 2 includes a disk-shaped suction part 20 and an annular frame 21 that supports the suction part 20. The suction part 20 is a porous member having a large number of pores, and the upper surface of the suction part 20 serves as a holding surface 200 on which the workpiece 14 is suction-held. The upper surface 210 of the frame 21 is formed flush with the holding surface 200.

[0017] A suction source (not shown) is connected to the holding surface 200 of the holding means 2. For example, when the workpiece 14 is placed on the holding surface 200, the suction source is operated, so that the workpiece 14 can be sucked and held on the holding surface 200.

[0018] Furthermore, a rotation mechanism (not shown) is provided in the holding means 2. By using the rotation mechanism, the holding means 2 can be rotated.

[0019] A cover 28 is disposed around the holding means 2, and the cover 28 is connected to the bellows 27 so as to be stretchable. When the holding means 2 moves in the Y-axis direction, the cover 28 moves integrally with the holding means 2 in the Y-axis direction, causing the bellows 27 to expand and contract.

[0020] The leading edge detection means 5 is disposed on the +Y direction side of the holding means 2. The leading edge detection means 5 is fixed to, for example, the cover 28, and is movable in the ±Y direction together with the holding means 2. The leading edge detection means 5 includes a base 53 and a light projecting / receiving element 54 disposed on the base 53. The light projecting / receiving element 54 includes a light projecting section 50 that projects measurement light, and a light receiving section 51 that receives the measurement light projected from the light projecting section 50. The light receiving section 51 is disposed opposite the light projecting section 50. A recess 540 is formed between the light projecting section 50 and the light receiving section 51, penetrating in the X-axis direction. The segment grinding wheel 360 can enter the recess 540.

[0021] The tip detection means 5 also includes a detection unit 55 that detects the segment grindstone 360 ​​or the gap 363. The detection unit 55 has a function of measuring the amount of light received by the light-receiving unit 51, which changes when the segment grindstone 360 ​​enters between the light-projecting unit 50 and the light-receiving unit 51, by converting the amount of light received into a voltage value, and detecting the segment grindstone 360 ​​or the gap 363 based on the change in voltage.

[0022] 2 and 3, the grinding device 1 is equipped with an air nozzle 7 that injects air onto the grinding wheel 36 positioned at a position where the tip detection means 5 can detect the tip of the segment grindstone 360. The air nozzle 7 is equipped with a light-projecting unit air injection unit 70 that blows air onto the light-projecting unit 50, and a light-receiving unit air injection unit 71 that injects air onto the light-receiving unit 51. The light-projecting unit air injection unit 70 and the light-receiving unit air injection unit 71 are connected to an air source 72. As shown in Fig. 2, the light-projecting air injection part 70 and the light-receiving air injection part 71 are disposed so that the direction of the air ejected from each of them is neither parallel nor perpendicular to the tangent direction of the rotation orbit of the segment grindstone 360 ​​at the position where the air hits. Furthermore, at the position where the air hits the segment grindstone 360, the angle between the direction of the air ejected from the light-projecting air injection part 70 and the tangent direction of the rotation orbit of the segment grindstone 360 ​​is substantially equal to the angle between the direction of the air ejected from the light-receiving air injection part 71 and the tangent direction of the rotation orbit of the segment grindstone 360. Furthermore, as shown in Fig. 3, the light-projecting air injection part 70 and the light-receiving air injection part 71 are disposed so that the direction of the air ejected from each of them is neither parallel nor perpendicular to the lower surface 362 of the segment grindstone 360. In the illustrated example, the air nozzle 7 is integrated with the tip detection means 5, but the two may be configured as separate entities.

[0023] With the grinding wheel 36 positioned in a position where the tip detection means 5 can detect the tip of the segment grinding wheel 360, the grinding wheel 36 can be rotated by spraying air from the light-emitting air spraying portion 70 and the light-receiving air spraying portion 71 of the air nozzle 7 toward the inner surface 365, outer surface 366, and bottom surface 362 of the grinding wheel 36. In the air nozzle 7, the rotation speed of the grinding wheel 36 can be adjusted by adjusting the flow rate of the air supplied from the air source 72.

[0024] The air nozzle 7 also has a function of removing water droplets and the like adhering between the light projector 50 and the light receiver 51 by injecting air from the light projector air injection portion 70 and the light receiver air injection portion 71 of the air nozzle 7. That is, in the illustrated example, the light projector air injection portion 70 and the light receiver air injection portion 71 have both a function of rotating the grinding wheel 36 and a function of removing water droplets and the like. Note that another nozzle may be provided in addition to the light projector air injection portion 70 and the light receiver air injection portion 71, and the function of rotating the grinding wheel 36 and the function of removing water droplets and the like may be realized by separate nozzles.

[0025] A counter 60 is connected to the leading end detection means 5, which counts the number of segment grindstones 360 or the number of gaps 363 while the grinding wheel 36 is rotating. In addition, a determination unit 61 is connected to the counter 60, which determines whether the segment grindstone 360 ​​has fallen off based on the value of the counter 60.

[0026] The counter 60 has a function of counting up the number of segment grindstones 360 every time the detection unit 55 detects the segment grindstones 360. The counter 60 also has a function of counting up the number of gaps 363 every time the detection unit 55 detects the gaps 363. For example, when the grinding wheel 36 rotates at 10 rpm, which is a speed at which the tip end detection means 5 can detect the segment grindstone 360 ​​and the gap 363, if the detection unit 55 detects the segment grindstone 360, the count value of the counter 60 increases. For example, the counter 60 can count the number of segment grindstones 360 detected by the detection unit 55 during one rotation of the grinding wheel 36.

[0027] The number of segmented grindstones 360 can be stored in advance in the judgment unit 61. By comparing the number of segmented grindstones 360 per rotation of the grinding wheel 36 counted by the counter 60 with the number of segmented grindstones 360 stored in the judgment unit 61, it can be determined whether or not a segmented grindstone 360 ​​has fallen off.

[0028] 2. Grinding Equipment Operation (Grinding) The operation of the grinding apparatus 1 when grinding the workpiece 14 using the grinding apparatus 1 will be described. When grinding the workpiece 14 using the grinding device 1, first, the workpiece 14 shown in Fig. 1 is placed on the holding surface 200 of the holding means 2. Then, a suction source (not shown) connected to the holding means 2 is operated to transmit the generated suction force to the holding surface 200. As a result, the workpiece 14 is sucked and held on the holding surface 200.

[0029] With the workpiece 14 being suction-held on the holding surface 200 , the holding means 2 is moved in the +Y direction using a Y-axis moving means (not shown) or the like, and positioned below the grinding means 3 . Next, the holding means 2 is rotated using a rotation mechanism not shown in the figure to rotate the workpiece 14 held on the holding surface 200, and the motor 32 is used to rotate the segment grinding wheel 360 around the rotating shaft 35.

[0030] With the workpiece 14 rotating about the rotation shaft 25 and the segmented grindstone 360 ​​rotating about the rotation shaft 35, the grinding means 3 is lowered in the -Z direction using the grinding feed means 4. By lowering the segmented grindstone 360 ​​in the -Z direction, the lower surface 362 of the segmented grindstone 360 ​​comes into contact with the upper surface 140 of the workpiece 14. With the lower surface 362 in contact with the upper surface 140 of the workpiece 14, the segment grindstone 360 ​​is further lowered in the -Z direction, thereby grinding the workpiece 14. After grinding of the workpiece 14 is completed, the grinding means 3 is moved in the +Z direction using the grinding feed means 4 to move the segment grinding wheel 360 away from the upper surface 140 of the workpiece 14, and then the workpiece 14 is transported away from the holding surface 200 of the holding means 2.

[0031] (Determining whether a segmented grinding wheel has fallen off) In the grinding device 1, it is determined whether or not the segment grindstone 360 ​​has fallen off before grinding the workpiece 14. Hereinafter, the operation of the grinding device 1 when determining whether or not the segment grindstone 360 ​​has fallen off will be described. When determining whether the segment grinding wheel 360 has fallen off, the tip detection means 5 shown in Figure 1 is activated to project measurement light from the light-projecting unit 50 toward the light-receiving unit 51, and the tip detection means 5 is moved so that the rotational orbit of the segment grinding wheel 360 is positioned above the recess 540.

[0032] Then, the grinding wheel 36 is lowered an appropriate distance in the -Z direction using the grinding feed means 4. Then, the segmented grindstone 360 ​​enters the recessed portion 540 of the light projecting and receiving element 54, and the lower surface 362 of the segmented grindstone 360 ​​is positioned below the height position of the light projecting and receiving line 52 (see FIG. 2) that connects the light projecting unit 50 and the light receiving unit 51 in a straight line.

[0033] 2 is operated to supply air to the light projector air jet unit 70 and the light receiver air jet unit 71. This causes a predetermined flow rate of air to be jetted from the light projector air jet unit 70 and the light receiver air jet unit 71 toward both side surfaces 365, 366 and the lower surface 362 of the grinding wheel 36, and the grinding wheel 36 rotates under the pressure of the air. The rotation speed of the grinding wheel 36 is, for example, 10 rpm. In other words, the air jetting section 71 is disposed below the segment grindstone 360 ​​and jets air obliquely upward, so that the grinding wheel 36 can be rotated along the direction of the air jetting.

[0034] Here, when the grinding wheel 36 rotates with the lower surface 362 of the segment grinding wheel 360 positioned below the height position of the light-projecting and receiving line 52 which connects the light-projecting section 50 and the light-receiving section 51 in a straight line, a state in which the segment grinding wheel 360 overlaps the light-projecting and receiving line 52 and blocks the light, and a state in which the segment grinding wheel 360 does not overlap the light-projecting and receiving line 52 and does not block the light are repeated alternately.

[0035] FIG. 4 shows a graph of the change in voltage detected by the detection unit 55 when the measurement light projected from the light-projecting unit 50 is repeatedly blocked and unblocked by the rotating segment grinding wheel 360.

[0036] A segment threshold value 80 and a gap threshold value 81 are set in advance in the detection unit 55. For example, when the measured light receiving voltage is greater than the gap threshold value 81, the measurement light projected from the light projecting unit 50 is deemed not to be blocked and a gap 363 is detected. When the measured light receiving voltage is less than the segment threshold value 80, the measurement light projected from the light projecting unit 50 is deemed to be blocked by the segment grinding wheel 360 and the segment grinding wheel 360 is detected.

[0037] When the measuring light projected from the light-projecting unit 50 is repeatedly blocked and unblocked by the rotating segment grinding wheel 360, two values, for example, a first light-receiving voltage 82 and a second light-receiving voltage 83, are alternately measured, as shown in FIG. 4. When the measured light receiving voltage is the first light receiving voltage 82, the first light receiving voltage 82 is smaller than the segment threshold value 80, so the segment grinding wheel 360 is detected by the detection unit 55. When the measured light receiving voltage is the second light receiving voltage 83, the second light receiving voltage 83 is larger than the gap threshold value 81, so the gap 363 is detected by the detection unit 55. Therefore, the detection unit 55 detects the segment grindstone 360 ​​and the gap 363 alternately.

[0038] As the grinding wheel 36 starts to rotate, the counter 60 starts to count the number of segmented grindstones 360. Then, every time the detection unit 55 detects a segmented grindstone 360, the count value of the counter 60 increases. Then, after the counter 60 counts the number of segmented grindstones 360 detected by the detection unit 55 during one rotation of the grinding wheel 36, the operation of the counter 60 is stopped and the injection of air from the air nozzle 7 is stopped, thereby stopping the rotation of the grinding wheel 36.

[0039] Thereafter, the count value counted by the counter 60 while the grinding wheel 36 makes one rotation is compared by the judgment unit 61 with the number of segment grindstones 360 previously stored in the judgment unit 61 . At this time, when the count value counted by the counter 60 during one rotation of the grinding wheel 36 matches the number of segment grindstones 360 previously stored in the judgment unit 61, it is determined that the segment grindstone 360 ​​has not fallen off. On the other hand, when the count value counted by the counter 60 during one rotation of the grinding wheel 36 is less than the number of segment grindstones 360 previously stored in the judgment unit 61, it is determined that the segment grindstone 360 ​​has fallen off.

[0040] Incidentally, instead of comparing the number of segmented grindstones 360 to determine whether the segmented grindstone 360 ​​has fallen off, as described above, it is also possible to determine whether the segmented grindstone 360 ​​has fallen off by comparing the number of gaps 363 . Specifically, the number of gaps 363 provided in the grinding wheel 36 is stored in the judgment unit 61 in advance, and the segment grindstone 360 ​​is positioned at an appropriate height and entered into the recess 540. Then, while projecting measurement light from the light projector 50, air is sprayed from the light projector air spray unit 70 of the air nozzle 7 to rotate the grinding wheel 36, and the number of gaps 363 is counted by the counter 60 every time the detection unit 55 detects a gap 363. By counting the number of gaps 363 detected by the detection unit 55 during one rotation of the grinding wheel 36 and comparing the number of gaps 363 stored in the judgment unit 61 with the number of the counted gaps 363, it is possible to determine whether the segment grindstone 360 ​​has fallen off.

[0041] In the grinding device 1, when determining whether the segment grinding wheel 360 has fallen off, air is blown using the air nozzle 7 to rotate the grinding wheel 36 at a low speed of about 10 rpm, so there is no need for a motor to rotate the grinding wheel 36 at a low speed or a control unit to control the rotation, which is economical. [Explanation of symbols]

[0042] 1: Grinding device 10: Base 11: Column 14: Workpiece 140: Upper surface 2: Holding means 20: Suction part 200: Holding surface 21: Frame body 210: Top surface of frame body 27: Bellows 28: Cover 3: Grinding means 30: Spindle 31: Housing 32: Motor 33: Mount 35: Rotating shaft 36: Grinding wheel 360: Segment grinding wheel 361: Base 362: Underside 363: Gap 364: Segment length 365:Inner surface 366:Outer surface 4: Grinding feed means 40: Ball screw 41: Guide rail 42: Z-axis motor 43: Lifting plate 44: Holder 45: Rotating shaft 5: Leading edge detection means 50: Light projecting section 51: Light receiving section 52: Light projecting and receiving line 53: Base 54: Light emitting / receiving element 540: Recess 55: Detection section 60: Counter 61: Judgment section 7: Air nozzle 70: Light projecting part air injection part 71: Light receiving part air injection part 72: Air source 80: Segment threshold 81: Gap threshold 82: First light receiving voltage 83: Second light receiving voltage

Claims

1. A holding means for holding a workpiece on a holding surface; a grinding means having a rotatable grinding wheel on a base on which a plurality of segment grindstones are arranged in an annular manner with gaps provided therebetween, and which grinds a workpiece held by the holding means using the segment grindstones; a grinding feed means for moving the grinding means in a direction perpendicular to the holding surface; and a tip detection means for detecting whether or not the tip of the segment grindstone is present, an air nozzle for injecting air onto the grinding wheel positioned at a position where the tip end detection means can detect the tip end of the segment grindstone, and for rotating the grinding wheel at a speed that can be detected by the tip end detection means; a counter for counting the number of the segment grindstones or the number of the gaps detected by the tip detection means of the grinding wheel rotated by the air jetted from the air nozzle; and a judgment unit that judges whether the segment grinding wheel has fallen off based on the value of the counter.

2. The leading end detection means includes a light-projecting unit that projects measurement light, a light-receiving unit that is disposed opposite the light-projecting unit so that the segment grinding wheel can enter between the light-projecting unit and the light-receiving unit and that receives the measurement light projected from the light-projecting unit, and a detection unit that detects the segment grinding wheel or the gap based on a change in the amount of light received by the light-receiving unit caused by the segment grinding wheel entering between the light-projecting unit and the light-receiving unit, the air nozzle includes a light-projecting air jetting section that blows air onto the light-projecting section, and a light-receiving air jetting section that jets air onto the light-receiving section, The light-projecting air injection section and the light-receiving air injection section are disposed so that the direction of the air injected from each section is neither parallel nor perpendicular to the tangent direction of the rotation orbit of the segment grinding wheel at the position where the air hits, and have both the function of rotating the grinding wheel and the function of removing water droplets adhering between the light-projecting section and the light-receiving section.

2. The grinding apparatus according to claim 1.

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