Grinding device

Abstract

To reduce differences in height among concavities and convexities periodically formed on a surface to be ground along trajectories of a plurality of grinding stones, without using a non-contact thickness measuring instrument.SOLUTION: A grinding device is provided with: a holding table having a holding surface for holding a work-piece; a motor for a table for rotating the holding table; a spindle motor including a spindle; a grinding unit that can grind the work-piece with a grinding wheel mounted on a mount formed at the lower end part of the spindle; a display device on which a grinding condition for grinding the work-piece is displayed; and a controller that controls the motor for the table, the spindle motor, and the display device. The controller determines whether a rotation speed ratio which is the ratio of the rotation speed of the spindle to the rotation speed of the holding table is a natural number, with respect to the rotation speed of the holding table and the rotation speed of the spindle respectively set on the controller as grinding conditions for the work-piece; and when determining that the rotation speed ratio is the natural number, has a warning to the outside issued.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] A grinding machine is generally used to grind and thin a workpiece such as a semiconductor wafer. The grinding machine is equipped with a disk-shaped chuck table for suction-holding the workpiece. A grinding unit including a cylindrical spindle is provided above the chuck table.

[0003] A circular grinding wheel is attached to the lower end of the spindle via a disk-shaped mount. The grinding wheel has, for example, a circular base and a plurality of grinding wheels (i.e., a plurality of segment grinding wheels). The plurality of grinding wheels are arranged at approximately equal intervals along the circumferential direction of the base in a groove provided in one circular surface (for example, the bottom surface) of the base.

[0004] When performing in-feed grinding on a workpiece using a grinding device, the chuck table which holds the workpiece by suction and the spindle to which the grinding wheel is attached are each rotated in a predetermined direction, and the grinding unit is moved downward at a predetermined speed relative to the chuck table (i.e., grinding feed).

[0005] In in-feed grinding, the movement trajectories of multiple grinding wheels overlap with the holding surface of the chuck table in the height direction of the grinding machine so as to pass through the center of the holding surface. Within this overlapping area, the multiple grinding wheels come into contact with the workpiece in an arc-shaped area from a point on the outer periphery of the holding surface to the center of the holding surface.

[0006] In in-feed grinding, when a workpiece is thinned by grinding, slight irregularities may be periodically formed on the ground surface along the length direction of this arc-shaped region (see, for example, FIG. 4(a) of Patent Document 1). The irregularities formed on the ground surface may adversely affect the device chips manufactured from the workpiece.

[0007] The unevenness formed on the grinding surface is 1 (Unit: rpm (rotations per minute)) 2 (unit: rpm) ratio (i.e., A 2 / A 1 This becomes evident when the rotation speed ratio B, which is the ratio of the rotation speeds between the engine and the engine, is a natural number.

[0008] This is the spindle rotation speed A 2 is the chuck table rotation speed A 1 This is because, in a typical situation where the rotational speed ratio B is set higher than 1000, when the rotational speed ratio B is a natural number, the contact area with the surface to be ground is substantially fixed for each grinding wheel.

[0009] Furthermore, when the rotational speed ratio B is a natural number, if the workpiece is thinned to a predetermined thickness and then a grinding process (i.e., spark out) is performed to smooth the ground surface, slight irregularities that were formed on the ground surface before the spark out will not disappear during the spark out but will remain.

[0010] In order to reduce the unevenness formed when the rotation speed ratio B is a natural number like this, it has been proposed to measure the thickness of the workpiece using a non-contact thickness gauge such as a distance measuring instrument using a laser beam while the workpiece is being ground (see, for example, Patent Document 1).

[0011] In Patent Document 1, periodic thickness changes of a workpiece are detected, and in order to reduce the detected periodic thickness changes, the rotation speed ratio B is changed during grinding so that the rotation speed ratio B does not become an integer. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2023-307 A Summary of the Invention [Problem to be solved by the invention]

[0013] However, non-contact thickness gauges are generally expensive, and therefore, if such gauges are installed in a grinding device, the cost of the grinding device increases. Therefore, a method is required to suppress the above-mentioned unevenness while suppressing the cost of the grinding device.

[0014] The present invention has been made in consideration of these problems, and aims to reduce the height difference of the unevenness that is periodically formed on the ground surface along the trajectories of multiple grinding wheels without using a non-contact thickness gauge. [Means for solving the problem]

[0015] According to one aspect of the present invention, there is provided a grinding apparatus comprising: a holding table having a circular holding surface for holding a workpiece; a table motor for rotating the holding table around a rotation axis located at the radial center of the holding surface; a grinding unit having a spindle motor including a spindle arranged above the holding surface and capable of grinding the workpiece with a grinding wheel attached to a mount arranged at the lower end of the spindle; a display device for displaying grinding conditions for grinding the workpiece; and a controller having a processor and memory, and controlling the table motor, the spindle motor, and the display device, wherein the controller determines whether a rotation speed ratio, which is the ratio of the rotation speed of the spindle to the rotation speed of the holding table, is a natural number at the rotation speeds of the holding table and the spindle, respectively, set in the controller as the grinding conditions for the workpiece, and if the rotation speed ratio is a natural number, issues a warning to the outside.

[0016] Preferably, when the rotation speed ratio is a natural number, the controller operates at least the display device to issue a warning to the outside.

[0017] Also, preferably, when the controller determines that the rotation speed ratio is a natural number, it causes the display device to display recommended values ​​for either or both of the rotation speed of the holding table and the rotation speed of the spindle so that the rotation speed ratio is not a natural number.

[0018] Also, preferably, the table motor and the spindle motor are synchronous motors. Effect of the Invention

[0019] In a grinding device according to one embodiment of the present invention, a controller of the grinding device determines whether a rotation speed ratio, which is the ratio of the rotation speed of the spindle to the rotation speed of the holding table, is a natural number, and if the rotation speed ratio is a natural number, a warning is issued to the outside by operating equipment provided in the grinding device.

[0020] Therefore, before starting grinding of the workpiece with the grinding device, the operator can adjust the rotation speed ratio to reduce the height difference of the unevenness periodically formed on the ground surface along the trajectories of the grinding wheels. In other words, the height difference of the unevenness can be reduced without using a non-contact thickness gauge. [Brief description of the drawings]

[0021] [Figure 1] FIG. [Diagram 2] FIG. 2A is an enlarged perspective view of the chuck table and the grinding wheel, and FIG. 2B is a plan view of the chuck table and the grinding wheel. [Diagram 3] FIG. 3(A) is a cross-sectional view of a workpiece when the rotation speed ratio is a natural number, and FIG. 3(B) is a cross-sectional view of a workpiece when the rotation speed ratio is a positive number that is not a natural number. [Figure 4] FIG. 4 is a flow chart showing a procedure for setting the rotation speed. [Diagram 5] FIG. 13 is a diagram showing an example of a screen for inputting the rotation speed of a spindle. [Figure 6]FIG. 13 is a diagram showing an example of a screen including a warning display recommending a change in the rotation speed of the spindle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a grinding device 2. In Fig. 1, the X-axis direction and the Y-axis direction are perpendicular to each other on a horizontal plane, and the Z-axis direction (up-down direction, height direction) is perpendicular to the horizontal plane.

[0023] The grinding device 2 includes a base 4 that supports or houses each of the components. A rectangular parallelepiped opening 4a having a longitudinal portion disposed along the X-axis direction is formed on the upper surface side of the base 4. An X-axis direction movement mechanism (not shown) having a ball screw is provided below the opening 4a.

[0024] The X-axis direction moving mechanism has a pair of guide rails arranged approximately parallel to the X-axis direction. An X-axis direction moving plate is slidably supported on the pair of guide rails. A nut portion is provided on the lower surface side of the X-axis direction moving plate.

[0025] A screw shaft arranged along the X-axis direction is rotatably coupled to the nut portion via a number of balls. The screw shaft is disposed between a pair of guide rails, and a drive source such as a stepping motor is connected to one end of the screw shaft.

[0026] When the screw shaft is rotated by a drive source, the X-axis direction moving plate moves along the X-axis direction. A disk-shaped chuck table (holding table) 6 is disposed above the X-axis direction moving plate. The chuck table 6 has a disk-shaped frame body made of non-porous ceramics.

[0027] A disk-shaped recess is formed in the upper part of the frame, and a disk-shaped porous plate made of porous ceramic is fixed in the recess. A suction source (not shown), such as a vacuum pump, is connected to the porous plate through a flow path formed in the frame.

[0028] The upper surface of the porous plate and the upper surface of the frame are substantially flush with each other to form a circular holding surface 6a in plan view. However, the porous plate has a conical shape with the center in the radial direction being higher by about 10 μm to 30 μm than the outer periphery.

[0029] When negative pressure from the suction source is transmitted to the porous plate, the workpiece 11 placed on the holding surface 6a is deformed to follow the shape of the holding surface 6a and is sucked and held by the holding surface 6a. The workpiece 11 has a single crystal substrate (i.e., a wafer) made of a semiconductor material such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN).

[0030] Devices such as ICs (Integrated Circuits) are formed on the front surface of the wafer. During grinding, the back surface of the wafer becomes the grinding surface 11a (see FIG. 2(A)). To protect the devices from damage, a protective tape 13 made of resin and having the same diameter as the wafer is attached to the front surface of the wafer.

[0031] The frame is rotatably supported by an annular table base (not shown) including a bearing. A cylindrical rotating shaft 10 is provided at the radial center of the table base, and the center of the upper end of the rotating shaft 10 is fixed to the center of the bottom surface of the frame, which corresponds to the radial center 6c of the holding surface 6a (see FIG. 2(B)).

[0032] The bottom surface of the table base is provided with a tilt adjustment mechanism 8. The tilt adjustment mechanism 8 is supported by the above-mentioned X-axis direction moving plate. The tilt adjustment mechanism 8 has a fixed support shaft 8a, a first movable support shaft 8b, and a second movable support shaft 8c, which are each provided on the outer periphery of the bottom surface of the table base.

[0033] The fixed support shaft 8a, the first movable support shaft 8b, and the second movable support shaft 8c are disposed at approximately equal intervals along the circumferential direction of the chuck table 6 (see FIG. 2(B)). The tilt adjustment mechanism 8 supports the table base so that the rotation shaft 10 is slightly tilted with respect to the Z-axis direction. However, since the tilt angle of the rotation shaft 10 is very small, the rotation shaft 10 is shown to be approximately parallel to the Z-axis direction in FIGS. 1 and 2(A).

[0034] As a result of the rotation axis 10 being slightly tilted with respect to the Z-axis direction, the arc-shaped region 6b (see FIG. 2(B)) from a point 6d on the outer periphery of the conical holding surface 6a to the center 6c is relatively high within the holding surface 6a and is at approximately the same height in the Z-axis direction.

[0035] 1, a driven pulley 10a is fixed to the lower end of a rotating shaft 10. A driving pulley 14a is fixed to the driven pulley 10a via an endless belt 12. The driving pulley 14a is fixed to the output shaft of a table motor 14. The table motor 14 is also supported by the above-mentioned X-axis direction moving plate.

[0036] The table motor 14 is a synchronous motor (also called a PM (Permanent Magnet) motor), and compared to an asynchronous motor (also called an induction motor), the table motor 14 has a rotation speed A set in a controller 48 described later. 1 Therefore, the set grinding conditions can be achieved with higher accuracy than with an asynchronous motor.

[0037] When the table motor 14 operates, the chuck table 6 rotates around the rotary shaft 10 via the endless belt 12. A rectangular plate 16a is fixed to the outer periphery of the chuck table 6 so as to cover a part of the opening 4a. Bellows-shaped cover members 16b are provided on both sides of the rectangular plate 16a in the X-axis direction.

[0038] When the driving source is operated to move the X-axis direction moving plate, the chuck table 6, the inclination adjustment mechanism 8, the table motor 14, the rectangular plate 16a, etc. move integrally along the X-axis direction. Also, the cover member 16b is expandable and contractable in the X-axis direction according to the position of the rectangular plate 16a.

[0039] When the workpiece 11 is loaded onto the chuck table 6, the chuck table 6 is moved to a loading / unloading position C located at one end of the opening 4a. 1 When grinding the workpiece 11 held by suction on the chuck table 6, the chuck table 6 is positioned at the grinding position C 2 will be placed in.

[0040] In the vicinity of the opening 4a, a grinding position C 2 A contact-type thickness measuring mechanism 18 is provided for measuring the thickness of the workpiece 11 held by suction on the chuck table 6 arranged on the support 6. The thickness measuring mechanism 18 has a first contactor that comes into contact with the workpiece 11 held by suction on the holding surface 6a, and a second contactor that comes into contact with the holding surface 6a that is not covered by the workpiece 11.

[0041] The thickness measuring mechanism 18 measures the thickness of the workpiece 11 in an area of ​​the holding surface 6a that does not overlap with a grinding wheel 40, which will be described later. The thickness measuring mechanism 18 is usually inexpensive compared to the non-contact thickness measuring device described above.

[0042] A rectangular parallelepiped support structure 4b is provided near the other end of the opening 4a so as to protrude from the upper surface of the base 4. A height adjustment unit 20 having a ball screw is provided on a side surface of the support structure 4b on one side in the Y-axis direction.

[0043] The height adjustment unit 20 is fixed to the side surface of the support structure 4b and has a pair of guide rails 22 arranged along the Z-axis direction. A rectangular Z-axis direction moving plate 24 is fixed to the pair of guide rails 22 so as to be slidable in the Z-axis direction.

[0044] A nut portion (not shown) is provided on the back surface of the Z-axis direction moving plate 24. A screw shaft 26 is rotatably coupled to the nut portion via a plurality of balls (not shown). A driving source 28 such as a stepping motor is connected to the upper end portion of the screw shaft 26. When the screw shaft 26 is rotated by the driving source 28, the Z-axis direction moving plate 24 moves along the Z-axis direction.

[0045] A cylindrical holding member 30 including a circular bottom surface is fixed to the surface of the Z-axis direction moving plate 24. A grinding unit 32 capable of grinding the workpiece 11 is fixed to the holding member 30. The grinding unit 32 has a cylindrical spindle housing 34 whose longitudinal direction is disposed along the Z-axis direction.

[0046] A spindle motor 36 is provided within the spindle housing 34. The spindle motor 36 includes a cylindrical spindle 36a that functions as a rotor and is disposed with its longitudinal direction along the Z-axis direction, and a stator 36b that is provided on the outer periphery of the spindle 36a.

[0047] The spindle motor 36 is a synchronous motor like the table motor 14, and rotates at a speed A set in the controller 48. 2 The spindle 36a is rotatably supported within the spindle housing 34 by an air bearing formed within the spindle housing 34.

[0048] A portion of the spindle 36a is housed in the spindle housing 34, but the lower end 36a of the spindle 36a 1 (See FIG. 2A) protrudes downward from the lower end of the spindle housing 34. 1 A disk-shaped mount 38 is fixed to the substrate 32.

[0049] An annular grinding wheel 40 is attached to the mount 38 using a bolt (see FIG. 2(A)). However, since the grinding wheel 40 is a consumable item, it is replaced as appropriate depending on the usage time, degree of wear, etc. In the commercial distribution of the grinding device 2, the grinding wheel 40 may not be attached to the mount 38.

[0050] The grinding wheel 40 includes an annular wheel base 40a having an outer diameter substantially the same as that of the mount 38. The wheel base 40a is made of a metal such as an aluminum alloy. An annular groove is formed on one surface (bottom surface) of the annular wheel base 40a.

[0051] A plurality of grinding wheels 40b are arranged in the grooves of the wheel base 40a at approximately equal intervals along the circumferential direction of the wheel base 40a. Each grinding wheel 40b is fixed to the wheel base 40a with an adhesive.

[0052] The grinding wheel 40b is a so-called segmented grinding wheel having a roughly block shape, and has abrasive grains made of diamond, cBN (cubic boron nitride), etc., and a bonding material (bond material) made of resin, ceramics, etc. that fixes the abrasive grains.

[0053] The grinding wheels 40b are arranged at approximately equal intervals along the circumferential direction of the wheel base 40a. When the spindle 36a is rotated, the trajectories of the bottom surfaces of the grinding wheels 40b define an annular grinding surface. In this embodiment, the grinding surface is arranged approximately parallel to the XY plane.

[0054] The grinding wheel 40, together with the mount 38 and the spindle 36a, constitutes the grinding unit 32. However, as described above, in commercial distribution, the grinding wheel 40 may not be attached to the mount 38. In other words, it is sufficient for the grinding unit 32 to be able to grind the workpiece 11 when the grinding wheel 40 is attached.

[0055] The grinding unit 32 is provided above the holding surface 6a. The grinding unit 32, the chuck table 6, the support structure 4b, etc. are covered by an exterior panel 42. A touch panel 44 is provided on one side of the exterior panel 42.

[0056] The touch panel 44 functions as an input device for the operator to input grinding conditions, etc. when grinding the workpiece 11, and also functions as a display device that displays the grinding conditions, GUI (Graphical User Interface), etc. inputted into the grinding device 2.

[0057] In addition, instead of the touch panel 44, a display device that does not have the function of an input device, such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display, may be provided on one side of the exterior panel .

[0058] In this case, however, an input device (such as a keyboard, mouse, trackball, touch pad, or digitizer) for an operator to input instructions to the grinding device 2 is separately provided on the grinding device 2. A cylindrical signal light 46 is provided on the top surface of the exterior panel 42.

[0059] The signal light 46 has a base 46a with a built-in speaker (not shown). The speaker may be provided in the grinding device 2 separately from the signal light 46. Light-emitting units 46b, 46c, 46d, and 46e, each capable of emitting light in a different color, are stacked on the base 46a along the Z-axis direction.

[0060] Each of the light-emitting units 46b, 46c, 46d, and 46e includes an LED and a light-diffusing lens arranged to surround the LED, and can light up or flash in different predetermined colors such as red, yellow, blue, and green.

[0061] The operations of the above-mentioned X-axis direction movement mechanism, suction source, tilt adjustment mechanism 8, table motor 14, height adjustment unit 20, spindle motor 36, touch panel 44, signal lamp 46, etc. are controlled by a controller 48.

[0062] 1 is illustrated outside the grinding device 2 for convenience of explanation, but in reality, it is disposed inside the base 4 or the exterior panel 42. The controller 48 is configured by a computer including, for example, a processor (processing device) 48a represented by a CPU (Central Processing Unit), and a memory (storage device) 48b.

[0063] The memory 48b includes a main storage device such as a dynamic random access memory (DRAM) and an auxiliary storage device such as a flash memory, a hard disk drive, or a solid state drive.

[0064] The auxiliary storage device stores software including a predetermined program. The functions of the controller 48 are realized by operating the processor 48a and other components in accordance with this software.

[0065] Next, with reference to Figures 2(A) to 3(B), an explanation will be given of the irregularities that are periodically formed on the grinding surface 11a along the trajectories of the multiple grinding wheels 40b in the area corresponding to the arc-shaped area 6b of the holding surface 6a when in-feed grinding is performed on the workpiece 11 using the grinding device 2.

[0066] Fig. 2(A) is an enlarged perspective view of the chuck table 6 and the grinding wheel 40 when in-feed grinding is performed on the workpiece 11, and Fig. 2(B) is a plan view of the chuck table 6 and the grinding wheel 40. Note that the grinding wheel 40 is simplified in Fig. 2(B).

[0067] As shown in FIG. 2(B), by lowering the upper end of the second movable support shaft 8c relatively to the upper ends of the fixed support shaft 8a and the first movable support shaft 8b, the arc-shaped region 6b from a point 6d on the outer periphery of the holding surface 6a to the center 6c becomes relatively higher within the holding surface 6a and becomes approximately the same height in the Z-axis direction.

[0068] Therefore, the region of the workpiece 11 held by suction on the holding surface 6a that corresponds to the arc-shaped region 6b in the Z-axis direction becomes the grinding region of the workpiece 11. During grinding, the chuck table 6 also rotates in addition to the grinding wheel 40, so that the entire surface of the workpiece 11 exposed upward is ground.

[0069] During in-feed grinding, the grinding conditions are set in the controller 48 by the operator inputting numbers, letters, etc. via the touch panel 44, or by copying previously used grinding conditions and loading them into the controller 48.

[0070] For example, the grinding feed rate (μm / s) of the grinding unit 32, the grinding time (s), and the rotation speed A of the chuck table 6 1 (rpm), the rotational speed A of the grinding wheel 40 (i.e., the spindle 36a) 2 (rpm) and the like are set in the controller 48 as the grinding conditions for the workpiece 11.

[0071] In this embodiment, the rotation speed A of the chuck table 6 1 is set to a predetermined value (e.g., 300 rpm) between 100 rpm and 400 rpm, and the rotation speed A of the spindle 36a 2 is set to a predetermined value (for example, 5100 rpm) between 1000 rpm and 7000 rpm.

[0072] However, the rotation speed A of the chuck table 6 1 The number of revolutions of the spindle 36a relative to A 2 The ratio (=A 2 / A 1 When the rotational speed ratio B, which is the ratio of the rotational speed of the grinding wheel 40b to the grinding surface 11a, is a natural number, the contact area with the grinding surface 11a is substantially fixed for each grinding wheel 40b.

[0073] In particular, since the grinding wheel 40 rotates around the spindle 36a and the grinding unit 32 descends at a predetermined grinding feed speed, the end of the bottom surface of the grinding wheel 40b in the circumferential direction of the wheel base 40a is likely to come into contact with the outer periphery of the workpiece 11 and chip.

[0074] Once a chip occurs in the grinding wheel 40b, the workpiece 11 is ground at the chipped area and non-chipped area of ​​the bottom surface of the grinding wheel 40b. When the rotation speed ratio B is a natural number, the contact area with the grinding surface 11a is approximately fixed for each grinding wheel 40b, so that periodic unevenness is formed along the trajectory of the multiple grinding wheels 40b.

[0075] 3A is a cross-sectional view of the workpiece 11 along the arc-shaped region 6b when the rotation speed ratio B is a natural number. In FIG. 3A, the recesses 15a and the protrusions 17a are periodically formed on the grinding surface 11a, and the height difference H between the recesses 15a and the protrusions 17a on the contour curve 19a of the grinding surface 11a is 1 is a relatively large value.

[0076] When the rotational speed ratio B is a natural number, a relatively large unevenness is formed as shown in FIG. 3(A) regardless of the natural number. For example, when the rotational speed ratio A 1 If the rotation speed is 300 rpm, then the rotation speed A 2 Even if the rotation speed ratio B is 17, the rotation speed A is 2 Even when the rotation speed is 4800 rpm (the rotation speed ratio B is 16), relatively large irregularities are formed on the grinding surface 11a.

[0077] On the other hand, the rotation speed A of the chuck table 6 is set so that the rotation speed ratio B is not a natural number. 1 and the rotation speed A of the spindle 36a 2 By changing either or both of the above, the height difference of the periodic unevenness can be reduced. For example, the rotation speed A of the chuck table 6 1 can be changed within the range of ±5 rpm, or the rotation speed A of the spindle 36a can be changed. 2 can be changed within a range of ±10 rpm.

[0078] Fig. 3(B) is a cross-sectional view of the workpiece 11 when the workpiece 11 is ground with the rotation speed ratio B set to a positive number that is not a natural number (i.e., a non-natural number). In particular, Fig. 3(B) shows a contour curve 19b of the ground surface 11a when the rotation speed ratio B is set to a positive number that is not a natural number and the chuck table 6 is rotated two times from the state shown in Fig. 3(A).

[0079] In FIG. 3B, the contact area with the grinding surface 11a is not fixed for each grinding wheel 40b, but is gradually reduced with the rotation of the chuck table 6. Therefore, the height difference H between the concave portion 15b and the convex portion 17b of the profile curve 19b is 2 is the height difference H of the contour curve 19a shown in FIG. 1 is smaller than.

[0080] Therefore, in this embodiment, instead of detecting the periodic unevenness using a non-contact thickness gauge, a determination unit of the controller 48 determines whether the rotation speed ratio B set in the controller 48 is a natural number or not. The determination unit is, for example, a program pre-stored in an auxiliary storage device.

[0081] Then, when the judgment unit of the controller 48 judges that the rotation speed ratio B is a natural number, the warning unit of the controller 48 operates a device provided in the grinding device 2 to issue a warning to the outside (see FIG. 6).

[0082] In this embodiment, the warning unit issues a warning display to the operator by operating at least the touch panel 44. In the case where a display device is provided instead of the touch panel 44, the warning unit issues a warning display to the operator by operating at least the display device.

[0083] In addition, the warning is not limited to the touch panel 44 (display device), but may be issued to the outside by emitting a warning sound from a speaker, or by illuminating one or more of the light-emitting units 46b to 46e.

[0084] The warning unit operates the touch panel 44, the speaker, the light emitting units 46b to 46e, and the like, and also adjusts the rotation speed A so that the rotation speed ratio B is not a natural number. 1 and A 2 Recommendations may also be calculated for either or both.

[0085] For example, the warning unit is 1 The recommended value changed within the range of ±5 rpm, and / or the rotation speed A of the spindle 36a 2 The warning unit then calculates a recommended value by varying the recommended value within a range of ±10 rpm. The warning unit then displays a window including the recommended value in front of multiple windows displayed on the screen of touch panel 44 (see FIG. 6).

[0086] Like the judgment unit, the warning unit is, for example, a program pre-stored in an auxiliary storage device. However, each of the judgment unit and the warning unit is not limited to a program pre-stored in a storage device, a storage medium, or the like, and may be configured with an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a PLD (Programmable Logic Device), or the like.

[0087] Next, referring to Figs. 4 to 6, the rotation speed A of the chuck table 6 1 and the rotation speed A of the spindle 36a 2 The procedure for setting the rotation speed A in the controller 48 will be described. 1 ,A 2 FIG. 1 is a flow chart showing a setting procedure.

[0088] First, the operator inputs the rotation speed A of the chuck table 6 via the touch panel 44. 1 and the rotation speed A of the spindle 36a 2 FIG. 5 is an example of a screen displayed on the touch panel 44, in which the rotation speed A of the chuck table 6 is input. 1 After input, the rotation speed of spindle 36a is A2 FIG. 13 is a diagram showing an example of a screen for inputting.

[0089] In Fig. 5, the operator's hand 50 is shown in a simplified form. In the example shown in Fig. 5, the rotation speed A of the spindle 36a is 2 In addition, this initial input is not limited to being done manually by the operator, and may be done by copying the grinding conditions prepared in advance as described above.

[0090] Next, the rotation speed ratio B (=A 2 / A 1 The determination unit of the controller 48 determines whether or not the rotation speed ratio B is a natural number (S20 in FIG. 4). If the determination unit determines that the rotation speed ratio B is not a natural number (NO in S20), the flow ends.

[0091] On the other hand, if the judgment unit judges that the rotation speed ratio B is a natural number (YES in S20), the warning unit of the controller 48 displays on the touch panel 44 recommended values ​​for either or both of the rotation speeds A1 and A2 so that the rotation speed ratio B is not a natural number (S30).

[0092] FIG. 6 shows the rotation speed A of the spindle 36a. 2 FIG. 13 is a diagram showing an example of a screen including a warning display recommending a change in the rotation speed A 2 If you do not want to change the value to the recommended value, press NO when the warning is displayed, and then change the rotation speed A 2 Re-enter (S40).

[0093] In response to this, the operator 2 To change the value to the recommended value displayed, the user presses YES in the warning display (S40). The re-input value or the recommended value is judged again by the judgment unit (S20).

[0094] In this example, the rotation speed A of the chuck table 6 1 is 300 rpm, so the rotation speed A of the spindle 36a 2When the rotation speed ratio B (=A 2 / A 1 ) is 17 (i.e., a natural number), but the number of rotations A 2 is 5110 rpm, then the rotation speed ratio B is 17.033..., a positive number that is not a natural number.

[0095] In the example shown in FIG. 6, the rotation speed A 2 Only the change in the rotation speed A is proposed. 1 Re-input or recommendation of only the number of revolutions A may be performed. 1 and A 2 Re-entry or recommendation of values ​​for both may be performed.

[0096] In the grinding apparatus 2 of this embodiment, the controller 48 controls the rotation speed A of the chuck table 6. 1 The number of revolutions of the spindle 36a relative to A 2 It is determined whether the rotation speed ratio B, which is the ratio of the above, is a natural number, and if it is determined that the rotation speed ratio B is a natural number, the touch panel 44, the speaker, the light-emitting units 46b to 46e, etc. are operated to issue a warning to the outside.

[0097] Therefore, before starting grinding of the workpiece 11 with the grinding device 2, the operator can reduce the height difference of the unevenness periodically formed on the grinding surface 11a along the trajectories of the multiple grinding wheels 40b by adjusting the rotation speed ratio B. In other words, the height difference of the unevenness can be reduced without using a non-contact thickness gauge.

[0098] By the way, when the table motor 14 and the spindle motor 36 are synchronous motors, the rotation speed A set in the controller 48 1 ,A 2 is realized more faithfully than when an asynchronous motor is employed.

[0099] Therefore, when the rotation speed ratio B is a natural number, the height difference between the projections and recesses becomes significant. However, as described above, by shifting the rotation speed ratio B from a natural number using the controller 48, the height difference between the projections and recesses can be reduced while still using a synchronous motor.

[0100] In addition, in this embodiment, since the grinding surface 11a is not measured using a non-contact thickness gauge after grinding has progressed to a certain extent, there is also an advantage that grinding can be performed with reduced height differences in unevenness from the start of grinding. In addition, the structures, methods, etc. according to the above-mentioned embodiments can be modified as appropriate without departing from the scope of the purpose of the present invention.

[0101] In the above-described embodiment, a grinding wheel 40 having a so-called segment arrangement in which multiple grinding stones 40b are arranged at approximately equal intervals has been described. However, the grinding device 2 can also use a grinding wheel 40 having a so-called continuous arrangement in which a single annular grinding stone is fixed to the wheel base 40a.

[0102] In addition, grinding of the workpiece 11 at a rotation speed ratio B that is not a natural number can be applied to all grinding processes, such as (i) grinding performed while lowering the grinding unit 32, (ii) grinding performed while fixing the height position of the grinding unit 32 in the Z-axis direction (i.e., spark out), and (iii) grinding performed while raising the grinding unit 32 (i.e., escape cut). [Explanation of symbols]

[0103] 2: grinding device, 4: base, 4a: opening, 4b: support structure 6: Chuck table (holding table) 6a: holding surface, 6b: arc-shaped area, 6c: center, 6d: one point 8: Tilt adjustment mechanism 8a: fixed support shaft, 8b: first movable support shaft, 8c: second movable support shaft 10: rotating shaft, 10a: driven pulley, 12: endless belt 11: Workpiece, 11a: Surface to be ground, 13: Protective tape 14: table motor, 14a: drive pulley, 16a: rectangular plate, 16b: cover member 15a, 15b: concave portion, 17a, 17b: convex portion, 19a, 19b: contour curve 18: thickness measuring mechanism, 20: height adjustment unit 22: guide rail, 24: Z-axis direction moving plate, 26: screw shaft, 28: driving source 30: holding member, 32: grinding unit, 34: spindle housing 36: spindle motor, 36a: spindle, 36a 1 : Lower end, 36b: Stator 38: Mount 40: grinding wheel, 40a: wheel base, 40b: grinding stone 42: Exterior panel, 44: Touch panel 46: signal light, 46a: base, 46b, 46c, 46d, 46e: light-emitting parts 48: controller, 48a: processor, 48b: memory 50: Hand A 1 ,A 2 : Rotation speed, B: Rotation speed ratio, C 1 : Loading / unloading position, C 2 : Grinding position H 1 ,H 2 :Height difference

Claims

1. 1. A grinding apparatus comprising: A holding table having a circular holding surface for holding a workpiece; a table motor for rotating the holding table around a rotation axis disposed at a radial center of the holding surface; a grinding unit having a spindle motor including a spindle provided above the holding surface, and capable of grinding the workpiece with a grinding wheel attached to a mount provided at a lower end of the spindle; A display device that displays grinding conditions when grinding the workpiece; a controller having a processor and a memory, and controlling the table motor, the spindle motor, and the display device; Equipped with The controller determining whether or not a rotation speed ratio, which is a ratio of the rotation speed of the spindle to the rotation speed of the holding table, is a natural number in the rotation speed of the holding table and the rotation speed of the spindle, which are respectively set in the controller as the grinding conditions for the workpiece; The grinding device is characterized in that, when the rotation speed ratio is a natural number, a warning is issued to the outside.

2. 2. The grinding apparatus according to claim 1, wherein the controller operates at least the display device to issue a warning to the outside when the rotation speed ratio is a natural number.

3. The grinding device according to claim 2, characterized in that, when the controller determines that the rotation speed ratio is a natural number, it causes the display device to display recommended values ​​for either or both of the rotation speed of the holding table and the rotation speed of the spindle so that the rotation speed ratio is not a natural number.

4. 4. The grinding apparatus according to claim 1, wherein the table motor and the spindle motor are synchronous motors.

Images