JP7474144B2 - Grinding device and grinding method - Google Patents

Description

The present invention relates to a grinding device and a grinding method.

In grinding processing using a grinding device, as disclosed in Patent Document 1, for example, multiple polygonal workpieces are held by a chuck table. This chuck table is rotated around its center as an axis. An annular grinding wheel is positioned so that it passes through the center of the chuck table, and the grinding wheel is rotated. In this way, multiple workpieces are ground simultaneously to a specified thickness.

JP 2020-55080 A

The grinding wheel can come into contact with the radial area of the arc connecting the center and outer periphery of the chuck table. In this radial area, the area of the grinding wheel that comes into contact with the workpiece (contact area) varies. Here, the part of the workpiece that is ground when the contact area is large is relatively difficult to grind. On the other hand, the part of the workpiece that is ground when the contact area is small is relatively easy to grind. Therefore, thick and thin parts are created on the workpiece along the rotation direction of the chuck table.

Conventionally, the thickness of a workpiece is measured using a non-contact top surface height measuring device positioned a specified distance outward from the center of the chuck table. This measuring device calculates the difference between the holding surface height and the top surface height of the workpiece, and the calculated difference is recognized as the thickness.

In addition, by measuring the top surface height of multiple workpieces while rotating the chuck table, the highest position of the top surface of the workpieces held on the chuck table before grinding can be identified.

However, conventionally, during grinding, the top surface height of multiple workpieces is measured while the chuck table is rotated, but the top surface height of the part of the workpiece that is ground when the contact area of the grinding wheel is the smallest is not measured. As a result, the thickness of the part of the workpiece that is ground when the contact area of the grinding wheel is the smallest is thinner than the specified thickness.

Therefore, the object of the present invention is to prevent the workpieces from being over-ground when grinding multiple workpieces simultaneously.

The grinding device of the present invention is a grinding device comprising a chuck table that holds a polygonal workpiece by a plurality of holding surfaces arranged on the upper surface of a conical surface, a table rotation means that rotates the chuck table about its center, a grinding means that rotates an annular grinding wheel about its center and grinds the workpiece by the lower surface of the grinding wheel, a thickness measurement means that measures the thickness of the workpiece, and a control unit. The thickness measurement means comprises a non-contact height measurement device that is arranged above the holding surface and measures the height of the holding surface and the height of the upper surface of the workpiece held on the holding surface in a non-contact manner, a calculation unit that calculates the difference between the height of the holding surface and the height of the upper surface of the workpiece held on the holding surface, and a non-contact height measurement device that measures the thickness of the workpiece by a non-contact height measurement device arranged above the holding surface and measures the height of the holding surface and the height of the upper surface of the workpiece held on the holding surface in a non-contact manner, and a horizontal movement mechanism that moves the measuring device in the radial direction of the upper surface of the chuck table. The control unit includes a first control unit that positions the non-contact height measuring device at a first position where the upper surface heights of all of the multiple workpieces held on the holding surface can be measured before the grinding process begins, a second control unit that positions the non-contact height measuring device at a second position where the upper surface height of the portion of the workpiece to be ground when the area of the lower surface of the grinding wheel that contacts the workpieces is smallest can be measured, and a third control unit that grinds the workpiece by moving the grinding wheel in a direction approaching the workpiece while measuring the upper surface height of the workpiece with the non-contact height measuring device positioned at the second position.

The grinding method of the present invention is a grinding method for simultaneously grinding a plurality of workpieces with a grinding wheel while measuring the thickness of the polygonal workpieces held by a plurality of holding surfaces formed on the upper surface of a conical chuck table, and includes a holding step for holding the workpieces on the plurality of holding surfaces, a top surface height detection step for measuring the top surface height of the workpieces held by the plurality of holding surfaces with a non-contact height measuring device and detecting the top surface height of the highest workpiece, and a step for detecting the top surface height of the highest workpiece by moving the non-contact height measuring device to the position where the area of the bottom surface of the grinding wheel that contacts the workpiece is smallest. The method includes a measuring device positioning step for positioning the grinding wheel at a position where the top surface height of the portion of the workpiece to be ground can be measured, a grinding wheel lowering step for lowering the bottom surface of the grinding wheel at a first speed to a height a predetermined distance away from the highest top surface height of the workpiece detected in the top surface height detection step, and a grinding step for grinding the workpiece by moving the grinding wheel in a direction approaching the workpiece at a second speed slower than the first speed while measuring the top surface height of the workpiece with the non-contact height measuring device positioned in the measuring device positioning step.

In the present invention, the grinding process is carried out with a non-contact height gauge positioned at a position where the height of the top surface of the portion of the workpiece that is ground when the area of the bottom surface of the grinding wheel that contacts the workpiece is smallest can be measured. Here, the portion of the workpiece that is ground when the above-mentioned area is smallest is more likely to be ground than other portions. In other words, in the present invention, the grinding process is carried out while measuring the height of the portion of the workpiece that is likely to be ground deeply (the portion that is likely to become thin), so that over-grinding of the workpiece can be prevented.

FIG. 2 is a perspective view showing a configuration of a grinding device. FIG. 2 is an explanatory diagram showing a grindable area of a grinding wheel. FIG. 2 is an explanatory diagram showing a state in which the grinding area of the grinding wheel is at its smallest. FIG. 13 is an explanatory diagram showing a state in which the grinding area of the grinding wheel becomes relatively large. FIG. 13 is an explanatory diagram showing a state in which the grinding area of the grinding wheel becomes relatively large.

As shown in FIG. 1, the grinding device 1 according to this embodiment is a device for grinding a workpiece 2 as a workpiece, and includes a rectangular parallelepiped base 10, a column 11 extending upward, and a control unit 15 that controls each component of the grinding device 1. The workpiece 2 is a polygonal workpiece, for example a rectangular plate-shaped workpiece.

An opening 13 is provided on the upper surface side of the base 10. A holding means 30 is disposed within the opening 13. The holding means 30 includes a chuck table 31 having a holding surface 32 for holding the workpiece 2, a support member 33 for supporting the chuck table 31, and a table rotation means 34 for rotating the chuck table 31 and the support member 33.

The chuck table 31 has a conical upper surface. The chuck table 31 holds the workpiece 2 by a number of holding surfaces 32 arranged on the upper surface. In this embodiment, the chuck table 31 has four holding surfaces 32. Each holding surface 32 is formed so as to be slightly higher than the upper surface of the chuck table 31. The holding surfaces 32 are made of a porous material, and are connected to a suction source (not shown) to hold the workpiece 2 by suction.

In addition, a measurement table 35 having the same height as the holding surface 32 is provided on the upper surface of the chuck table 31.

The table rotation means 34 rotates the chuck table 31 around its center. In other words, the chuck table 31 can rotate together with the support member 33 around a rotation axis passing through the center of the chuck table 31 while holding the workpiece 2 with the holding surface 32 by the table rotation means 34 provided below.

A cover plate 39 is provided around the chuck table 31. A bellows cover 12 that expands and contracts in the Y-axis direction is connected to the cover plate 39. A Y-axis movement means 40 is provided below the holding means 30.

The Y-axis direction moving means 40 moves the holding means 30 and the grinding means 70 relative to each other in the Y-axis direction parallel to the holding surface 32. In this embodiment, the Y-axis direction moving means 40 is configured to move the holding means 30 in the Y-axis direction relative to the grinding means 70.

The Y-axis direction moving means 40 includes a pair of Y-axis guide rails 42 parallel to the Y-axis direction, a Y-axis moving table 45 that slides on the Y-axis guide rails 42, a Y-axis ball screw 43 parallel to the Y-axis guide rails 42, a Y-axis motor 44 connected to the Y-axis ball screw 43, and a holder 41 that holds these.

The Y-axis moving table 45 is slidably installed on the Y-axis guide rail 42. A nut portion (not shown) is fixed to the underside of the Y-axis moving table 45. The Y-axis ball screw 43 is screwed into this nut portion. The Y-axis motor 44 is connected to one end of the Y-axis ball screw 43.

In the Y-axis direction moving means 40, the Y-axis motor 44 rotates the Y-axis ball screw 43, causing the Y-axis moving table 45 to move in the Y-axis direction along the Y-axis guide rail 42. The holding means 30 is placed on the Y-axis moving table 45. Therefore, as the Y-axis moving table 45 moves in the Y-axis direction, the holding means 30 including the chuck table 31 moves in the Y-axis direction.

In this embodiment, the holding means 30 is moved along the Y-axis direction by the Y-axis moving means 40 between a work placement position at the front (-Y direction side) for placing the work 2 on the holding surface 32 and a work grinding position at the rear (+Y direction side) where the work 2 is ground.

As shown in FIG. 1, a column 11 is erected on the rear (+Y direction) side of the base 10. A grinding means 70 for grinding the workpiece 2 and a grinding feed means 50 are provided on the front side of the column 11.

The grinding feed means 50 moves the holding means 30 and the grinding means 70 relative to each other in the Z-axis direction (grinding feed direction) perpendicular to the holding surface 32. In this embodiment, the grinding feed means 50 is configured to move the grinding means 70 in the Z-axis direction relative to the holding means 30.

The grinding feed means 50 includes a pair of Z-axis guide rails 51 parallel to the Z-axis direction, a Z-axis moving table 53 that slides on the Z-axis guide rails 51, a Z-axis ball screw 52 parallel to the Z-axis guide rails 51, a Z-axis motor 54, and a holder 56 attached to the front (surface) of the Z-axis moving table 53. The holder 56 holds the grinding means 70.

The Z-axis moving table 53 is slidably installed on the Z-axis guide rail 51. A nut portion (not shown) is fixed to the rear side (back side) of the Z-axis moving table 53. The Z-axis ball screw 52 is screwed into this nut portion. The Z-axis motor 54 is connected to one end of the Z-axis ball screw 52.

In the grinding feed means 50, the Z-axis motor 54 rotates the Z-axis ball screw 52, causing the Z-axis moving table 53 to move in the Z-axis direction along the Z-axis guide rail 51. As a result, the holder 56 attached to the Z-axis moving table 53 and the grinding means 70 held by the holder 56 also move in the Z-axis direction together with the Z-axis moving table 53.

The grinding means 70 includes a spindle housing 71 fixed to the holder 56, a spindle 72 rotatably held in the spindle housing 71, a rotary motor 73 that rotates the spindle 72, a wheel mount 74 attached to the lower end of the spindle 72, and a grinding wheel 80 supported by the wheel mount 74.

The spindle housing 71 is held by the holder 56 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be perpendicular to the upper surface of the chuck table 31, and is rotatably supported by the spindle housing 71.

The rotation motor 73 is connected to the upper end side of the spindle 72. This rotation motor 73 rotates the spindle 72 around a rotation axis extending in the Z-axis direction.

The wheel mount 74 is formed in a disk shape and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 80.

The grinding wheel 80 is formed to have approximately the same diameter as the wheel mount 74. The grinding wheel 80 has grinding wheels 90, which are multiple segmented grinding wheels arranged in a ring shape.

The grinding wheel 80 is rotated by the rotary motor 73 via the spindle 72 and the wheel mount 74, with the center of the annular grinding stone 90 as its axis. As a result, the upper surface of the workpiece 2 held by the chuck table 31 arranged at the workpiece grinding position is ground by the grinding stone 90.
In this manner, the grinding means 70 is configured to rotate the annular grinding wheel 90 about its center as an axis, and grind the workpiece 2 with the lower surface of the grinding wheel 90 .

A thickness measuring means 60 is disposed on the side of the opening 13 in the base 10. The thickness measuring means 60 can measure the top surface height and thickness of the workpiece 2 held on the holding surface 32 in a non-contact manner.

The thickness measuring means 60 includes a non-contact height measuring device 61, which is a distance measuring device, a calculation unit 63 that performs calculations based on the measurement results of the non-contact height measuring device 61, and a horizontal movement mechanism 62 that moves the non-contact height measuring device 61 in the radial direction (horizontal direction) of the upper surface of the chuck table 31.

The horizontal movement mechanism 62 includes a rotating support 66 extending in the Z-axis direction from the side of the opening 13 in the base 10, and an arm 65 extending horizontally from the upper end of the rotating support 66. A non-contact height measuring device 61 is attached to the tip of the arm 65. The horizontal movement mechanism 62 is configured to move the non-contact height measuring device 61 attached to the tip of the arm 65 in the horizontal direction by rotating the rotating support 66 around a rotation axis extending in the Z-axis direction.

The non-contact height measuring device 61 is positioned above the holding surface 32 of the chuck table 31 and measures, in a non-contact manner, the height of the holding surface 32 and the top surface height of the workpiece 2 held on the holding surface 32.

The non-contact height measuring device 61 is, for example, a laser distance measuring device. For example, the non-contact height measuring device 61 irradiates the workpiece 2 with a laser beam and receives the light reflected from the top surface of the workpiece 2. The non-contact height measuring device 61 can measure the top surface height of the workpiece 2 held on the holding surface 32 based on the light reflected from the top surface of the workpiece 2.

The non-contact height measuring device 61 also irradiates the measurement table 35 with a laser beam and receives the light reflected from the upper surface of the measurement table 35. The non-contact height measuring device 61 can measure the height of the measurement table 35, i.e., the height of the holding surface 32, based on the light reflected from the upper surface of the measurement table 35.

The calculation unit 63 can also calculate the thickness of the workpiece 2 by calculating the difference between the height of the holding surface 32 and the height of the top surface of the workpiece 2 held on the holding surface 32.

The control unit 15 also includes a first control unit 16, a second control unit 17, and a third control unit 18. Below, the functions of the control unit 15 and the method for grinding the workpiece 2 in the grinding device 1 are described.

The grinding method according to this embodiment is a method for simultaneously grinding multiple workpieces 2 using a grinding wheel 90 while measuring the thickness of the workpieces 2 held by multiple holding surfaces 32 formed on the upper surface of a conical chuck table 31.

[Holding process]
In this embodiment, first, the control unit 15 or an operator holds the workpiece 2 on each of the multiple holding surfaces 32 of the chuck table 31 of the holding means 30 located at the workpiece placement position. Then, the control unit 15 moves the holding means 30 including the chuck table 31 to the workpiece grinding position.

[Top surface height detection process]
In this process, the first control unit 16 of the control unit 15 positions the non-contact height measuring device 61 at a first position where the top surface heights of all of the multiple workpieces 2 held on the holding surface 32 can be measured before grinding processing begins.

That is, as shown in FIG. 2, the first control unit 16 controls the horizontal movement mechanism 62 (see FIG. 1) of the thickness measurement means 60 to move the non-contact height gauge 61 in a horizontal direction parallel to the holding surface 32 and position it at the first position 100. This first position 100 is a position where the non-contact height gauge 61 can detect the top surface height of the four workpieces 2 held on the four holding surfaces 32 of the chuck table 31 rotating in the direction indicated by the arrow 301, that is, a position where the non-contact height gauge 61 passes above the four workpieces 2. The first control unit 16 recognizes this first position 100 in advance.

In FIG. 2, the area measured by the non-contact height measuring device 61 positioned at the first position 100 is shown as a measurement trajectory 611, which is the trajectory of the non-contact height measuring device 61 that rotates relative to the rotating chuck table 31.

Figure 2 also shows the grinding wheel 90 located above the chuck table 31 in the workpiece grinding position, and a grindable area 91 that is a part of the underside of the grinding wheel 90. The grindable area 91 of the grinding wheel 90 is an area (portion) of the grinding wheel 90 that can grind the workpiece 2 held on the holding surface 32. Any part of the grindable area 91 of the grinding wheel 90 rotating in the direction indicated by the arrow 302 comes into contact with the upper surface of the workpiece 2 and grinds it.

Then, the first control unit 16 uses the non-contact height measuring device 61 positioned at the first position 100 to measure the top surface height of the workpieces 2 held on the multiple holding surfaces 32 before grinding, and detects (recognizes) the top surface height of the highest workpiece 2.

In this process, the first control unit 16 also detects the height of the measurement table 35 using the non-contact height measuring device 61.

[Measurement instrument positioning process]
In this process, the second control unit 17 of the control unit 15 positions the non-contact height measuring device 61 at a second position where it can measure the top surface height of the portion of the workpiece 2 being ground when the area of contact between the underside of the grinding wheel 90 and the workpiece 2 is smallest.

In other words, when the four workpieces 2 held on the four holding surfaces 32 are ground by the grinding wheel 90, the area of the bottom surface of the grinding wheel 90 that comes into contact with the workpieces 2 varies depending on the rotation state (rotation angle) of the chuck table 31.

For example, in the rotating state of the chuck table 31 shown in FIG. 3, the grinding area 92 of the grinding wheel 90 is the smallest. In this state, only a portion of one workpiece 2 is positioned in the grindable area 91 of the grinding wheel 90. In this case, the grinding area 92 of the grinding wheel 90 is an area that contacts only a portion of this one workpiece 2, and the area of the grinding area 92, i.e., the area of the bottom surface of the grinding wheel 90 that contacts the workpiece 2, is the smallest. Here, the grinding area 92 is an area included in the grindable area 91, and is an area that contacts the bottom surface of the grinding wheel 90 with the workpiece 2 to grind it.

On the other hand, in the rotating state of the chuck table 31 shown in Figures 4 and 5, the area of the grinding region 92 becomes relatively large. In this state, two workpieces 2 are positioned in the grindable region 91 of the grinding wheel 90. In this case, the grinding region 92 of the grinding wheel 90 becomes a relatively wide region that spans the two workpieces 2.

Then, in the measuring device positioning process, the non-contact height measuring device 61 is positioned at a second position 101, as shown in FIG. 3, where the top surface height of the portion of the workpiece 2 being ground when the area of the bottom surface of the grinding wheel 90 that contacts the workpiece 2 (the area of the grinding region 92) is smallest can be measured. The second control unit 17 recognizes this second position 101 in advance.

[Grinding wheel lowering process]
In this step, the control unit 15 controls the grinding feed means 50 (see FIG. 1 ) to lower the lower surface of the grinding wheel 90 at a first speed to a height that is a predetermined distance away from the highest upper surface height of the workpiece 2 detected in the upper surface height detection step. This first speed is faster than a second speed, which is the speed of the grinding wheel 90 when grinding the workpiece 2 with the grinding wheel 90.

[Grinding process]
In this step, the third control unit 18 (see FIG. 1) of the control unit 15 controls the grinding feed means 50 (see FIG. 1) to move the grinding wheel 90 in a direction approaching the workpiece 2 while measuring the top surface height of the workpiece 2 with the non-contact height measuring device 61 positioned at the second position 101 as shown in FIG. 3. At this time, the control unit 15 moves the grinding wheel 90 at a second speed that is slower than the first speed, which is the speed at which the grinding wheel 90 moves in the grinding wheel lowering step. In this manner, the third control unit 18 grinds the workpiece 2.

At this time, the calculation unit 63 of the thickness measurement means 60 calculates the thickness of the workpiece 2 based on the measurement result of the non-contact height measurement device 61. For example, when the thickness of the workpiece 2 calculated by the calculation unit 63 reaches a predetermined thickness, the third control unit 18 determines that grinding of the workpiece 2 is complete, and controls the grinding feed means 50 to move the grinding wheel 90 upward to separate it from the workpiece 2, thereby completing the grinding process.

As described above, in this embodiment, the grinding process is carried out with the non-contact height measuring device 61 positioned at the second position 101 where the top surface height of the portion of the workpiece 2 being ground when the grinding area 92 of the grinding wheel 90 is at its smallest can be measured.

Here, the portion of the workpiece 2 that is ground when the grinding area 92 of the grinding wheel 90 is at its smallest is more likely to be ground than other portions. That is, in this embodiment, the grinding process is performed while measuring the height of the portion of the workpiece 2 that is likely to be ground deeply (the portion that is likely to become thin), so that over-grinding of the workpiece 2 can be prevented.

In addition, in this embodiment, in the grinding wheel lowering process, the control unit 15 lowers the lower surface of the grinding wheel 90 at a relatively fast first speed to a height that is a predetermined distance away from the top surface height of the highest workpiece 2. Therefore, the grinding wheel 90 located above the chuck table 31 can be quickly lowered to near the workpiece 2 without coming into contact with the workpiece 2 held on the holding surface 32 of the chuck table 31. This makes it possible to shorten the time required for grinding.

In addition, in the grinding wheel lowering process, the grinding wheel 90 is stopped at a position a predetermined distance away from the top surface height of the highest workpiece 2, so that the grinding wheel 90 can be prevented from coming into contact with the workpiece 2 at high speed. Note that it is preferable that the above-mentioned predetermined distance is appropriately determined taking into consideration the shortening of the process time and the avoidance of contact of the grinding wheel 90 with the workpiece 2.

1: grinding device, 2: workpiece, 10: base, 11: column,
12: bellows cover, 13: opening,
15: control unit, 16: first control unit, 17: second control unit, 18: third control unit,
30: holding means, 31: chuck table, 32: holding surface,
33: Support member, 34: Table rotating means, 35: Measuring table, 39: Cover plate,
40: Y-axis direction moving means, 50: grinding feed means,
60: thickness measuring means, 61: non-contact height measuring device, 63: calculation unit,
62: horizontal movement mechanism, 65: arm portion, 66: rotating support column,
100: first position, 101: second position, 611: measurement trajectory,
70: grinding means, 72: spindle, 73: rotation motor,
80: Grinding wheel, 90: Grinding stone,
91: Grindable area, 92: Grinding area

Claims (2)

A grinding device comprising: a chuck table that holds a polygonal workpiece by a plurality of holding surfaces arranged on an upper surface of a conical surface; a table rotating means that rotates the chuck table about an axis at its center; a grinding means that rotates an annular grinding wheel about an axis at its center and grinds the workpiece by a lower surface of the grinding wheel; a thickness measuring means that measures a thickness of the workpiece; and a control unit,
The thickness measuring means is
A non-contact height measuring device is disposed above the holding surface and measures the height of the holding surface and the height of the upper surface of the workpiece held on the holding surface in a non-contact manner;
A calculation unit that calculates a difference between the height of the holding surface and the height of an upper surface of a workpiece held on the holding surface;
a horizontal movement mechanism for moving the non-contact height measuring device in a radial direction of the upper surface of the chuck table,
The control unit
a first control unit that positions the non-contact height measuring device at a first position where the heights of all of the upper surfaces of the plurality of workpieces held on the holding surface can be measured before a grinding process is started;
a second control unit that positions the non-contact height measuring device at a second position where the height of the upper surface of the portion of the workpiece being ground when the area of the lower surface of the grinding wheel that contacts the workpiece is smallest can be measured; and
a third control unit that grinds the workpiece by moving the grinding wheel in a direction approaching the workpiece while measuring the top surface height of the workpiece by the non-contact height measuring device positioned at the second position;
Equipped with
Grinding equipment. A grinding method for simultaneously grinding a plurality of polygonal workpieces with a grinding wheel while measuring thicknesses of the polygonal workpieces held by a plurality of holding surfaces formed on an upper surface of a conical chuck table, comprising:
a holding step of holding a workpiece on the plurality of holding surfaces;
a top surface height detection step of measuring the top surface heights of the workpieces held by the plurality of holding surfaces with a non-contact height measuring device to detect the top surface height of the highest workpiece;
a measuring device positioning step of positioning the non-contact height measuring device at a position where the non-contact height measuring device can measure the height of the upper surface of the portion of the workpiece being ground when the area of the lower surface of the grinding wheel that contacts the workpiece is the smallest;
a grinding wheel lowering step of lowering a lower surface of the grinding wheel at a first speed to a height that is a predetermined distance away from the highest upper surface height of the workpiece detected in the upper surface height detection step;
a grinding step of grinding the workpiece by moving the grinding wheel in a direction approaching the workpiece at a second speed slower than the first speed while measuring the top surface height of the workpiece with the non-contact height measuring device positioned in the measuring device positioning step;
A grinding method comprising:

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