Grinding device, detection method, and grinding wheel

Abstract

To provide a grinding device capable of detecting the wear of a grinding wheel with higher accuracy.SOLUTION: A grinding device includes: a grinding mechanism comprising a spindle to which a grinding wheel is mounted at its end, and a motor which rotates the spindle; a notification module; and a controller. On a first surface side of a wheel base of the grinding wheel, a member that has a shorter distance from the first surface to a tip of the member than that of a grinding stone is arranged. The controller performs processing of monitoring magnitude of a load applied to rotation of the spindle during grinding of a workpiece, and processing of causing the notification module to notify of such information when the magnitude of the load deviates from a reference range.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a grinding apparatus, a detection method, and a grinding wheel used when grinding a workpiece such as a wafer.

Background Art

[0002] In order to realize a small and lightweight device chip, there is an increasing opportunity to thinly process a disk-shaped wafer on which a device such as an integrated circuit is provided on the surface side. For example, the surface side of the wafer is held by a chuck table, and a grinding wheel in which a plurality of grinding wheels are fixed to an annular wheel base, and the chuck table are rotated relative to each other, and the grinding wheel is pressed against the back surface of the wafer while supplying a liquid such as pure water, whereby the wafer is ground and thinned (see, for example, Patent Document 1).

[0003] By the way, in the above-described method, as the grinding of the wafer progresses, the grinding wheel wears out, and the height (effective length) of each grinding wheel decreases. When the height of each grinding wheel decreases, for example, the space (gap) existing between two adjacent grinding wheels also becomes smaller, and the dischargeability of the liquid discharged to the outside of the grinding wheel through this space decreases. Further, when the height of each grinding wheel extremely decreases, the wheel base of the grinding wheel or an adhesive or the like fixing the grinding wheel to the wheel base comes into contact with the wafer, and the wafer cannot be properly ground.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to prevent the occurrence of such problems, for example, it is conceivable to estimate the decrease in the height (consumption amount) of the grinding wheel from the difference in the thickness of the wafer (grinding amount) before and after grinding and the distance by which the grinding wheel moves (descends) during grinding, and to measure the timing of replacing the grinding wheel. However, in this method, since the distance traveled by the grinding wheel is not necessarily calibrated, the accuracy of estimating the decrease in height is low, and it is difficult to say that the timing of replacement due to wear of the grinding wheel can be detected with sufficiently high accuracy.

[0006] Therefore, an object of the present invention is to provide a grinding apparatus, a detection method, and a grinding wheel capable of detecting wear of the grinding wheel with higher accuracy.

Means for Solving the Problems

[0007] According to one aspect of the present invention, there is provided a grinding apparatus for grinding a workpiece, comprising: a holding table for holding the workpiece; a wheel base having an annular first surface and a grinding wheel having a grinding stone disposed on the first surface side of the wheel base; a spindle for mounting the opposite side of the first surface of the grinding wheel to an end portion; and a grinding mechanism including a motor for rotating the spindle, a notification module for notifying information regarding the grinding mechanism, a processing device, and a storage device, and a controller for controlling the grinding mechanism and the notification module by operating the processing device according to a program stored in the storage device. A member having a smaller distance from the first surface to the tip than the grinding stone is disposed on the first surface side of the wheel base, and the controller, according to the program, rotates the spindle with the motor to bring the grinding stone into contact with the workpiece to grind the workpiece, monitors the magnitude of the load applied to the rotation of the spindle when grinding the workpiece, and when the magnitude of the load deviates from a reference range, notifies the notification module to that effect. A grinding apparatus is provided that performs the processes.

[0008] Preferably, when grinding the workpiece according to the program, the controller performs a process of monitoring the value of the current flowing through the motor as the magnitude of the load, and when the value of the current deviates from a reference range, the controller performs a process of notifying the notification module to that effect.

[0009] Preferably, the member is configured such that the load when grinding the workpiece is larger than that of the grinding wheel. The member may be disposed on the wheel base in a manner of being buried in the proximal end side of the grinding wheel or overlapping the proximal end side of the grinding wheel.

[0010] According to another aspect of the present invention, there is provided a grinding apparatus for grinding a workpiece, including a holding table for holding the workpiece, a grinding wheel having a wheel base with an annular first surface and a grinding wheel disposed on the first surface side of the wheel base, a spindle attached to an end of the grinding wheel on a side opposite to the first surface, and a grinding mechanism including a motor for rotating the spindle, a notification module for notifying information regarding the grinding mechanism, a controller including a processing device and a storage device, and the controller controls the grinding mechanism and the notification module by operating the processing device according to a program stored in the storage device. A groove having a depth from the tip that is shallower than the distance from the first surface to the tip is opened on the surface of the tip of the grinding wheel. The controller performs a process of grinding the workpiece by rotating the spindle with the motor to bring the grinding wheel into contact with the workpiece according to the program, a process of monitoring the magnitude of the load applied to the rotation of the spindle when grinding the workpiece, and a process of notifying the notification module to that effect when the magnitude of the load deviates from a reference range.

[0011] Preferably, when grinding the workpiece according to the program, the controller performs a process of monitoring the value of the current flowing through the motor as the magnitude of the load, and when the value of the current deviates from a reference range, the controller performs a process of notifying the notification module to that effect.

[0012] In the grinding device applied to each side surface, preferably, the notification module is any one of a display, an indicator light, and a speaker.

[0013] According to a further aspect of the present invention, there is provided a detection method for detecting wear of a grinding wheel used when grinding a workpiece, the method including: a grinding step of rotating a grinding wheel including a wheel base having an annular first surface, a grinding abrasive disposed on the first surface side of the wheel base, and a member disposed on the first surface side of the wheel base and having a smaller distance from the first surface to the tip than the grinding abrasive, and bringing the grinding abrasive into contact with the workpiece to grind the workpiece; a monitoring step of monitoring the magnitude of the load applied to the rotation of the grinding wheel when performing the grinding step; and a notification step of notifying when the magnitude of the load deviates from a reference range.

[0014] Preferably, the member is configured such that the load when grinding the workpiece is larger than that of the grinding abrasive. The member may be disposed on the wheel base in a manner of being buried in the base end side of the grinding abrasive or overlapping the base end side of the grinding abrasive.

[0015] According to a further aspect of the present invention, there is provided a detection method for detecting wear of a grinding wheel used when grinding a workpiece, the method including: a grinding step of rotating a grinding wheel including a wheel base having an annular first surface and a grinding abrasive disposed on the first surface side of the wheel base, and bringing the grinding abrasive into contact with the workpiece to grind the workpiece, wherein a groove having a depth from the tip shallower than the distance from the first surface to the tip is opened on the tip surface of the grinding abrasive; a monitoring step of monitoring the magnitude of the load applied to the rotation of the grinding wheel when performing the grinding step; and a notification step of notifying when the magnitude of the load deviates from a reference range.

[0016] In the detection method for each side surface, preferably, in the monitoring step, as the magnitude of the load, the value of the current flowing through the motor that rotates the grinding wheel is monitored, and in the notification step, when the value of the current deviates from the reference range, that fact is notified.

[0017] According to a further aspect of the present invention, there is provided a grinding wheel used when grinding a workpiece, the grinding wheel including a wheel base having an annular first surface, a grinding abrasive disposed on the first surface side of the wheel base, and a member disposed on the first surface side of the wheel base and having a smaller distance from the first surface to the tip than the grinding abrasive.

[0018] Preferably, the member is configured such that the load when grinding the workpiece is larger than that of the grinding abrasive. The member may be disposed on the wheel base in a manner of being buried in the proximal end side of the grinding abrasive or overlapping the proximal end side of the grinding abrasive.

Advantages of the Invention

[0019] In each aspect of the present invention, the grinding wheel has a member having a smaller distance from the first surface of the wheel base to the tip than the grinding abrasive, or a grinding abrasive in which a groove shallower than the distance from the first surface of the wheel base to the tip of the grinding abrasive opens to the tip surface.

[0020] Therefore, when the grinding abrasive is consumed, the tip of the member contacts the workpiece, or the area of contact between the workpiece and the grinding abrasive increases due to the loss of the groove, and the load applied to the grinding of the workpiece becomes larger than when the grinding abrasive is not consumed.

[0021] Thus, by monitoring the magnitude of this load and determining whether the magnitude of the load deviates from the reference range, the consumption of the grinding wheel can be detected with higher accuracy than before.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

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BEST MODE FOR CARRYING OUT THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing the structure of a grinding apparatus 2 according to the present embodiment. In FIG. 1, some elements constituting the grinding apparatus 2 are represented by functional blocks. Also, in the following description, the X-axis (first horizontal axis), Y-axis (second horizontal axis), and Z-axis (vertical axis) used are perpendicular to each other. Further, in the following description, terms such as up and down indicating position and orientation are attached only for the convenience of explanation and do not limit the usage mode of the present invention in any way.

[0024] As shown in FIG. 1, the grinding apparatus 2 includes a base 4 that supports various elements constituting the grinding apparatus 2. On the upper surface of the base 4, a recess 4a that is long in a direction generally parallel to the X-axis is formed. Inside the recess 4a, a ball screw type X-axis movement mechanism 6 is disposed. The X-axis movement mechanism 6 includes a rotational drive source (not shown), such as a motor, connected to the ball screw, and a moving table (not shown), and moves this moving table along the X-axis.

[0025] Above the moving table, it is covered by a table cover 8. Also, bellows-shaped dust and splash-proof covers 10 that can expand and contract according to the movement of the moving table (table cover 8) are attached to the front and rear of the table cover 8. On the upper part of this moving table, a holding table (chuck table) 12 configured to hold the plate-shaped workpiece 11 from the lower side is disposed in a manner partially exposed from the table cover 8.

[0026] The workpiece 11 is, for example, a disk-shaped wafer made of a semiconductor material such as silicon. That is, this workpiece 11 has a circular surface 11a and a circular back surface 11b on the side opposite to the surface 11a. The surface 11a side of the workpiece 11 is partitioned into a plurality of small regions by a plurality of streets (lines to be divided) that intersect each other, and devices such as integrated circuits (ICs) are formed in each small region.

[0027] The grinding apparatus 2 of the present embodiment is used, for example, when grinding (grinding process) the back surface 11b side of the workpiece 11 or the like. When grinding the back surface 11b side of the workpiece 11, since the surface 11a side of the workpiece 11 is held by the holding table 12, it is desirable to attach a protective member such as a protective tape made of a material such as resin to the surface 11a side of the workpiece 11. Thereby, the impact applied to the surface 11a side when grinding the back surface 11b side of the workpiece 11 is alleviated by the protective member, and the devices and the like of the workpiece 11 are protected.

[0028] In this embodiment, a disk-shaped wafer made of a semiconductor material such as silicon is used as the workpiece 11. However, the material, shape, structure, size, etc. of the workpiece 11 are not limited to this embodiment. For example, a substrate made of other materials such as semiconductors, ceramics, resins, metals, etc. can be used as the workpiece 11. Similarly, the type, quantity, shape, structure, size, arrangement, etc. of the devices are not limited to the above-described embodiment. The workpiece 11 may not have a device formed thereon.

[0029] The holding table 12 includes, for example, a disk-shaped (cylindrical) frame body 14 made of ceramics or the like. On the upper surface side of the frame body 14, a concave portion having a circular opening at the upper end is formed. A holding plate 16 configured in a porous disk shape using ceramics or the like is fixed to this concave portion.

[0030] The upper surface (holding surface) 16a of the holding plate 16 is configured in a shape corresponding to the side surface of a cone, for example, and functions as a holding surface for holding the workpiece 11. The height difference (level difference) between the center of the upper surface 16a corresponding to the apex of the cone and the outer peripheral edge of the upper surface 16a is about 10 μm to 30 μm.

[0031] The lower surface side of the holding plate 16 is connected to a suction source (not shown) via a flow path provided inside the frame body 14 and a valve (not shown) arranged outside the frame body 14. Therefore, when the suction source is operated and the valve is opened with the workpiece 11 (or the protection member) in contact with the upper surface 16a of the holding plate 16, a suction force acts on the workpiece 11 (or the protection member) from the upper surface 16a, and the workpiece 11 is held by the holding table 12. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used.

[0032] A motor (not shown) as a rotational drive source is connected to the lower part of the frame body 14. The holding table 12 rotates around a rotation axis parallel to the Z axis or a rotation axis slightly inclined with respect to the Z axis such that the center of the upper surface 16a of the holding plate 16 becomes the center of rotation by the power generated by this motor.

[0033] When the moving table is moved along the X-axis by the above-described X-axis moving mechanism 6, the holding table 12 also moves along the X-axis. Specifically, the X-axis moving mechanism 6 moves the holding table 12, for example, between a front loading / unloading area where the workpiece 11 is loaded onto the holding table 12 or unloaded from the holding table 12, and a grinding area behind the loading / unloading area.

[0034] A columnar support structure 18 is provided behind the grinding area (that is, behind the X-axis moving mechanism 6). A Z-axis moving mechanism 20 is arranged on the front surface side of the support structure 18. The Z-axis moving mechanism 20 includes a pair of guide rails 22 that are long along the Z-axis, and a moving plate 24 is attached to the pair of guide rails 22 in a manner that it can slide along the Z-axis.

[0035] A nut portion (not shown) constituting a ball screw is provided on the rear surface side of the moving plate 24, and a screw shaft 26 that is long along the Z-axis is connected to the nut portion in a manner that it can rotate. A rotary drive source 28 such as a motor is connected to one end of the screw shaft 26. By rotating the screw shaft 26 by the rotary drive source 28, the moving plate 24 moves along the guide rail 22, that is, along the Z-axis.

[0036] A support 30 is provided on the front surface of the moving plate 24. A grinding mechanism 32 capable of grinding the workpiece 11 held by the holding table 12 positioned in the grinding area is supported by the support 30. The grinding mechanism 32 includes a spindle housing 34 supported by the support 30. A spindle 36 having an axis parallel to the Z-axis or slightly inclined with respect to the Z-axis is accommodated in the spindle housing 34 in a manner that it can rotate around its axis.

[0037] The lower end of the spindle 36 is exposed from the lower end surface of the spindle housing 34, and a disk-shaped mount 38 made of a metal such as stainless steel or aluminum is fixed to the lower end of the spindle 36. For example, a plurality of holes (not shown) penetrating the mount 38 in the thickness direction are provided at the outer edge of the mount 38, and a fastening tool 40 such as a bolt is inserted into each hole.

[0038] A grinding wheel 42 is attached to the lower surface of the mount 38 by the above-described fastening tool 40. That is, the grinding wheel 42 is attached to the lower end of the spindle 36 via the mount 38 and the fastening tool 40. Further, a motor (not shown) as a rotational drive source connected to the upper end side of the spindle 36 is housed in the spindle housing 34. By the power of this motor, the grinding wheel 42 rotates together with the spindle 36.

[0039] FIG. 2 is a side view schematically showing the structure of the grinding wheel 42. The grinding wheel 42 includes an annular wheel base 44 formed of a metal such as stainless steel or aluminum. The wheel base 44 has an annular upper surface (second surface) 44a and an annular lower surface (first surface) 44b opposite to the upper surface 44a.

[0040] At the upper surface 44a of the wheel base 44, the upper ends of a plurality of fastening holes (not shown) to which the fastening tool 40 is fastened are open. For example, a thread is provided on the inner wall surface of each fastening hole. When the fastening tool 40 is fastened to the fastening hole on the upper surface 44a through the hole of the mount 38 while the upper surface 44a of the wheel base 44 is in contact with the lower surface of the mount 38, the wheel base 44 is fixed to the mount 38. That is, the upper surface 44a side of the wheel base 44 is attached to the lower end of the spindle 36.

[0041] Further, at the lower surface 44b of the wheel base 44, for example, the lower ends of annular grooves (not shown) extending along the circumferential direction of the wheel base 44 are open. In these annular grooves, a plurality of rectangular grinding wheels 46 in which abrasive grains such as diamond are dispersed in a binder such as resin, ceramics, and metal, and one or a plurality of rectangular members (members) 48 for detecting wear are fixed at substantially equal intervals by an adhesive or the like with a gap therebetween.

[0042] That is, on the lower surface 44b side of the wheel base 44, a plurality of grinding wheels 46 and one or a plurality of wear detection members 48 are arranged so as not to overlap each other along the circumferential direction of the wheel base 44. The lower portions of the lower sides of the respective grinding wheels 46 and the lower portions of the lower sides of the respective wear detection members 48 are located outside the grooves and are exposed below the lower surface 44b.

[0043] The wear detection member 48 is configured such that the distance d1 from its lower end (tip) 48a to the lower surface 44b of the wheel base 44 is smaller than the distance d2 from the lower end (tip) 46a of the unused grinding wheel 46 to the lower surface 44b of the wheel base 44, for example. The distance d1 is, for example, 0.5 mm or more and 2.0 mm or less, typically 1.0 mm, and the distance d2 is, for example, 3.5 mm or more and 20 mm or less, typically 7.0 mm.

[0044] Therefore, in plunge grinding in which the lower end 46a of the grinding wheel 46 is pressed against the upper surface (back surface 11b, etc.) of the workpiece 11, the wear detection member 48 does not contact the workpiece 11 until the distance from the lower end 46a of the grinding wheel 46 to the lower surface 44b of the wheel base 44 becomes equal to or less than the distance d1. In other words, the wear detection member 48 does not contact the workpiece 11 unless the grinding wheel 46 is significantly worn.

[0045] Here, the shapes and sizes of the upper surface (not shown) of the wear detection member 48 and the surface of the lower end 48a are generally the same as the shapes and sizes of the upper surface (not shown) of the grinding wheel 46 and the surface of the lower end 46a. As a result, the wear detection member 48 can be handled in the same way as the grinding wheel 46 and fixed in the groove of the wheel base 44, facilitating the manufacture of the grinding wheel 42. However, the shapes and sizes of the upper surface (not shown) of the wear detection member 48 and the surface of the lower end 48a may be different from the shapes and sizes of the upper surface (not shown) of the grinding wheel 46 and the surface of the lower end 46a.

[0046] Also, the wear detection member 48 is typically composed of a material equivalent to that of the grinding wheel 46. This reduces the likelihood of machining defects occurring in the workpiece 11 due to contact with the wear detection member 48, even if the grinding wheel 46 wears and the wear detection member 48 comes into contact with the workpiece 11. However, the wear detection member 48 may be composed of any material different from the grinding wheel 46.

[0047] In addition, the wear detection member 48 is configured such that, for example, the load when grinding the workpiece 11 is greater than that of the grinding wheel 46. That is, the coefficient of kinetic friction between one wear detection member 48 and the workpiece 11 is greater than the coefficient of kinetic friction between one grinding wheel 46 and the workpiece 11. As a result, when the wear detection member 48 comes into contact with the workpiece 11 (such as the back surface 11b), the load applied to the grinding of the workpiece 11 significantly increases. Based on this load variation, it is possible to easily confirm that the grinding wheel 46 has worn.

[0048] Specifically, if the strength of the wear detection member 48 (mechanical strength, typically flexural strength) is made higher than that of the grinding wheel 46, the load when grinding the workpiece 11 with the wear detection member 48 will be greater than when grinding with the grinding wheel 46. To make the strength of the wear detection member 48 higher than that of the grinding wheel 46, for example, the content (concentration) of abrasive grains, the amount of pores (porosity), the type of binder, the temperature of molding or firing, etc. are adjusted.

[0049] That is, when the abrasive grain content of the wear detection member 48 is made larger than the abrasive grain content of the grinding wheel 46 (increasing the concentration of abrasive grains), the load when grinding the workpiece 11 with the wear detection member 48 becomes larger than when grinding with the grinding wheel 46. Also, when the amount (volume) of pores contained in the wear detection member 48 is reduced compared to the amount (volume) of pores contained in the grinding wheel 46 (lowering the porosity), the load when grinding the workpiece 11 with the wear detection member 48 becomes larger than when grinding with the grinding wheel 46.

[0050] Further, when the binder constituting the grinding wheel 46 is a vitrified type, by making the binder constituting the wear detection member 48 a resin type, the load when grinding the workpiece 11 with the wear detection member 48 becomes larger than when grinding with the grinding wheel 46. Similarly, when the binder constituting the grinding wheel 46 is a resin type, by making the binder constituting the wear detection member 48 a metal type, the load when grinding the workpiece 11 with the wear detection member 48 becomes larger than when grinding with the grinding wheel 46.

[0051] And when the temperature when molding or firing the wear detection member 48 is raised compared to the temperature when molding or firing the grinding wheel 46, the load when grinding the workpiece 11 with the wear detection member 48 becomes larger than when grinding with the grinding wheel 46. However, the wear detection member 48 does not necessarily have to be configured such that the load when grinding the workpiece 11 becomes larger than that of the grinding wheel 46.

[0052] The amount of change in the load at the timing when the wear detection member 48 comes into contact with the upper surface (such as the back surface 11b) of the workpiece 11 can also be adjusted by changing the ratio between the total area (S1) of the surfaces of the lower ends 46a of the plurality of grinding wheels 46 and the total area (S2) of the surfaces of the lower ends 48a of the one or more wear detection members 48. The range of the value obtained by dividing the total area (S2) by the total area (S1) (= S2 / S1) is, for example, 0.50 or less, and preferably 0.014 or more and 0.072 or less.

[0053] There is no particular limitation on the specific method for changing the ratio between the total area (S2) and the total area (S1). For example, by changing the ratio between the number of grinding wheels 46 and the number of wear detection members 48, the ratio between the total area (S2) and the total area (S1) can be changed. Also, by making the shape or size of the surface of the lower end 48a of the wear detection member 48 different from the shape or size of the surface of the lower end 46a of the grinding wheel 46, the ratio between the total area (S2) and the total area (S1) may be changed.

[0054] Below the grinding wheel 42 (grinding mechanism 32) configured as described above, a nozzle (not shown) for supplying a liquid (grinding fluid) such as pure water is arranged at the portion (processing point) where the workpiece 11 and the grinding wheel 46 come into contact. Instead of this nozzle, or together with the nozzle, a liquid supply port used for supplying the liquid may be provided on the grinding wheel 42 or the like.

[0055] As shown in FIG. 1, a controller (control unit) 50 is connected to each element of the grinding apparatus 2. The controller 50 is constituted by a computer including, for example, a processing device 52 and a storage device 54, and controls the operations of each element of the grinding apparatus 2 described above so that the workpiece 11 is appropriately ground.

[0056] The processing device 52 is typically a CPU (Central Processing Unit) and performs various processes necessary for controlling the above-described elements. The storage device 54 includes, for example, a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive or a flash memory. The functions of this controller 50 are realized, for example, by the processing device 52 operating according to a program (software) stored in the storage device 54.

[0057] The controller 50 is connected to an input device 56 and an output device (notification module) 58 that serve as a user interface. The input device 56 is, for example, a keyboard, a mouse, etc., and inputs commands from the operator to the controller 50. The output device 58 transmits (notifies) information regarding the state of the grinding device 2 to the operator.

[0058] The output device 58 is, for example, a display (display device) that transmits information by displaying an image or the like, an indicator light that transmits information by the color of light or the state of light emission (light emission, blinking, turning off, etc.), a speaker that transmits information by sound, etc. Note that as the input device 56 and the output device 58, an input / output device such as a touch screen that combines an input function and an output function may be used.

[0059] A part of the storage device 54, which is also a non-temporary recording medium readable by a computer or the like, stores a program for executing a series of processes (procedures) necessary for grinding the workpiece 11. By operating the processing device 52 according to this program, the controller 50 performs various processes necessary for grinding the workpiece 11.

[0060] FIG. 3 is a functional block diagram schematically showing the functional structure of the controller 50 realized by a program. As shown in FIG. 3, the controller 50 includes a grinding control unit 50a that performs various processes related to grinding the workpiece 11. For example, when a command from the operator to start grinding the workpiece 11 is input from the input device 56 to the controller 50, the grinding control unit 50a controls the operation of each element of the grinding device 2 and starts grinding the workpiece 11.

[0061] Specifically, for example, after the workpiece 11 is loaded onto the holding table 12 in the loading / unloading area, the grinding control unit 50a activates the X-axis movement mechanism 6 and moves the holding table 12 to the grinding area. Then, the grinding control unit 50a rotates the holding table 12 with a motor connected to the holding table 12 and rotates the grinding wheel 42 together with the spindle 36 with a motor connected to the spindle 36.

[0062] After that, the grinding control unit 50a operates the Z-axis movement mechanism 20 to lower the grinding mechanism 32. When the grinding mechanism 32 descends to a predetermined height, the lower end 46a of the grinding wheel 46 comes into contact with the upper surface (the back surface 11b, etc.) of the workpiece 11 held on the holding table 12, and the workpiece 11 is ground. Note that the grinding control unit 50a lowers the grinding mechanism 32 by the Z-axis movement mechanism 20 until, for example, the workpiece 11 reaches a target thickness (finish thickness).

[0063] Further, the controller 50 includes a monitoring determination unit 50b that monitors the value of the current flowing through the motor for rotating the spindle 36 as the load applied to the rotation of the grinding wheel 42 and makes a predetermined determination. For example, when the rotation of the spindle 36 starts, the monitoring determination unit 50b receives information regarding the value of the current flowing through the motor from a current sensor provided inside or outside the motor that rotates the spindle 36 at an arbitrary interval (time interval).

[0064] Then, the monitoring determination unit 50b compares this current value with a reference range. More specifically, the monitoring determination unit 50b determines whether or not the value of the current flowing through the motor has deviated from the reference range. That is, the monitoring determination unit 50b compares the magnitude of the load applied to the rotation of the grinding wheel 42 with the reference range, and determines whether or not the magnitude of the load applied to the rotation of the grinding wheel 42 has deviated from the reference range.

[0065] As described above, the grinding wheel 42 of the present embodiment includes one or a plurality of wear detection members 48 in which the distance from the lower surface 44b of the wheel base 44 to the lower end (that is, the height of the portion exposed from the wheel base 44) is smaller than that of the unused grinding wheel 46. Therefore, when the grinding wheel 46 is significantly worn and the lower end 48a of the wear detection member 48 comes into contact with the workpiece 11, the load applied to the rotation of the grinding wheel 42 increases, and as a result, the value of the current flowing through the motor also increases.

[0066] Therefore, by monitoring the value of the current corresponding to this load and determining whether the value of the current has deviated from the reference range, it is possible to appropriately detect the contact between the lower end 48a of the wear detection member 48 and the workpiece 11. The reference range for the determination is arbitrarily set based on, for example, the range of the value of the current that can be obtained when the wear detection member 48 is not in contact with the workpiece 11, etc.

[0067] In addition, based on the principle of detecting an increase in the current accompanying an increase in the load, the reference range for this determination has at least an upper limit. The upper limit of the reference range is, for example, 1.05 times or more and 1.50 times or less of the value (average value) of the current in a state where only the grinding wheel 46 is in contact with the workpiece 11, that is, in a state where the wear detection member 48 is not in contact with the workpiece 11, and typically, it is 1.25 times.

[0068] When the controller 50 determines that the value of the current has deviated from the reference range by the monitoring determination unit 50b, that is, when it is determined that the magnitude of the load has deviated from the reference range, it includes a notification processing unit 50c that causes the output device 58 to notify of that fact. For example, when the output device 58 is a display (display device), the notification processing unit 50c causes the output device 58 to display characters, symbols, figures, etc. so as to indicate that the value of the current has deviated from the reference range, that is, that the magnitude of the load has deviated from the reference range.

[0069] Also, for example, when the output device 58 is an indicator light, the notification processing unit 50c controls the color of the light or the light emission state of the output device 58 so as to indicate that the value of the current has deviated from the reference range, that is, that the magnitude of the load has deviated from the reference range. Also, for example, when the output device 58 is a speaker, the notification processing unit 50c causes the output device 58 to generate a sound so as to indicate that the value of the current has deviated from the reference range, that is, that the magnitude of the load has deviated from the reference range.

[0070] Next, a process performed to detect wear of the grinding wheel 42 described above, that is, a detection method for detecting wear of the grinding wheel 42, will be described. FIG. 4 is a flowchart showing the detection method according to the present embodiment. As shown in FIG. 4, in the detection method according to the present embodiment, first, a series of operations (grinding step ST1) for grinding the workpiece 11 are started.

[0071] FIG. 5 is a side view schematically showing a state in which the workpiece 11 is being ground. Note that, for convenience of explanation, cross-sections of some elements are shown in this FIG. 5. The grinding control unit 50a starts the rotation of the holding table 12 by a motor connected to the holding table 12, starts the rotation of the spindle 36 by a motor connected to the spindle 36, and starts the lowering of the grinding mechanism 32 by the Z-axis movement mechanism 20. When the lower end 46a of the grinding wheel 46 contacts the upper surface (the back surface 11b, etc.) of the workpiece 11, the workpiece 11 is ground as shown in FIG. 5.

[0072] Here, the number of revolutions per unit time (rotation speed) of the holding table 12 is set, for example, to 100 rpm or more and 500 rpm or less, and typically to 300 rpm. Also, the number of revolutions per unit time (rotation speed) of the grinding wheel 42 is set, for example, to 1000 rpm or more and 5000 rpm or less, and typically to 3000 rpm. And the lowering speed of the grinding mechanism 32 is set, for example, to 0.1 μm / s or more and 10 μm / s or less, and typically to 1 μm / s.

[0073] FIG. 6 is a side view schematically showing a state in which the grinding wheel 46 is worn. Note that, for convenience of explanation, cross-sections of some elements are shown in this FIG. 6. As shown in FIG. 6, when the grinding wheel 46 is worn and the lower end 48a of the wear detection member 48 comes into contact with the upper surface (the back surface 11b, etc.) of the workpiece 11, the load applied to the rotation of the grinding wheel 42 becomes extremely large, and the value of the current flowing through the motor for rotating the spindle 36 increases.

[0074] Therefore, when an operation for grinding the workpiece 11 is started, for example, the monitoring determination unit 50b starts monitoring the magnitude of the load applied to the rotation of the grinding wheel 42 (monitoring step ST2), that is, monitoring the value of the current flowing through the motor for rotating the spindle 36. Specifically, the monitoring determination unit 50b acquires information regarding the value of the current flowing through the motor from the current sensor as information regarding the magnitude of the load (information acquisition step ST2a).

[0075] When the monitoring determination unit 50b acquires information regarding the magnitude of the load, that is, information regarding the value of the current flowing through the motor, it compares the magnitude of the load indicated by this information, that is, the value of the current flowing through the motor, with a preset reference range. Then, it determines whether or not the magnitude of the load, that is, the value of the current flowing through the motor, has deviated from the reference range (load determination step ST2b).

[0076] When it is determined by the monitoring determination unit 50b that the magnitude of the load, that is, the value of the current flowing through the motor, has deviated from the reference range (YES in the load determination step ST2b), the notification processing unit 50c causes the output device 58 to notify the operator of this fact (notification step ST3). As a result, the operator can determine that the grinding wheel 46 has worn to such an extent that the lower end 48a of the wear detection member 48 contacts the workpiece 11, and can take measures such as replacing the grinding wheel 42.

[0077] On the other hand, when it is determined that the magnitude of the load, that is, the value of the current flowing through the motor, has not deviated from the reference range (NO in the load determination step ST2b), the monitoring determination unit 50b continues to monitor the magnitude of the load (monitoring step ST2). Specifically, the monitoring determination unit 50b acquires again information regarding the value of the current flowing through the motor from the current sensor (information acquisition step ST2a), and compares the value of the current indicated by this information with the reference range (load determination step ST2b).

[0078] When the above-described series of processes (detection method) ends, for example, the notification processing unit 50c causes the output device 58 to notify that the value has deviated from the reference range. When it is determined that the magnitude of the load, that is, the value of the current flowing through the motor, has deviated from the reference range (YES in the load determination step ST2b), the grinding control unit 50a may interrupt or cancel the operation for grinding the workpiece 11 regardless of the operator's instruction.

[0079] As described above, in the grinding apparatus 2 and the detection method according to the present embodiment, the grinding wheel 42 having the wear detection member (member) 48 in which the distance from the lower surface (first surface) 44b to the lower end (tip) of the wheel base 44 is smaller than that of the grinding wheel 46 is used.

[0080] Therefore, when the grinding wheel 46 wears, the lower end (tip) 48a of the wear detection member 48 contacts the workpiece 11, and the load applied to the grinding of the workpiece 11 becomes larger than when the grinding wheel 46 has not worn.

[0081] Therefore, by monitoring the magnitude of this load and determining whether or not the magnitude of the load has deviated from the reference range, it is possible to detect the wear of the grinding wheel with higher accuracy than in the past.

[0082] Note that the present invention is not limited to the description of the above-described embodiment and can be implemented with various modifications. For example, in the above-described embodiment, after the operation (grinding step ST1) for grinding the workpiece 11 is started, the monitoring (monitoring step ST2) of the magnitude of the load applied to the rotation of the grinding wheel 42 is started. However, after the monitoring of the magnitude of the load applied to the rotation of the grinding wheel 42 is started, the operation for grinding the workpiece 11 may be started.

[0083] Further, in the above-described embodiment, as the load applied to the rotation of the grinding wheel 42, the value of the current flowing through the motor for rotating the spindle 36 is monitored. However, as the load applied to the rotation of the grinding wheel 42, the value of the current flowing through the motor for rotating the holding table 12 or the like may be monitored.

[0084] In the above-described embodiment, a grinding wheel 42 is used in which a wear detection member 48 having an upper surface (not shown) and a lower end surface 48a having substantially the same shape and size as the shapes and sizes of the upper surface (not shown) and the lower end 46a of the grinding wheel 46 is disposed. However, a grinding wheel of another aspect may be used.

[0085] FIG. 7 is a side view schematically showing the structure of a grinding wheel 142 according to the second aspect. The basic structure of this grinding wheel 142 is the same as the structure of the grinding wheel 42. Specifically, the grinding wheel 142 includes an annular wheel base 144 having an annular upper surface (second surface) 144a and an annular lower surface (first surface) 144b opposite to the upper surface 144a.

[0086] At the lower surface 144b of the wheel base 144, the lower ends of annular grooves (not shown) along the circumferential direction of the wheel base 144 are open, and in these annular grooves, a plurality of rectangular parallelepiped grinding wheels 146 in which abrasive grains such as diamond are dispersed in a binder such as resin, ceramics, and metal are fixed at substantially equal intervals with gaps therebetween by an adhesive or the like.

[0087] Further, in the grinding wheel 142 according to the second aspect, as shown in FIG. 7, one or a plurality of rectangular parallelepiped wear detection members (members) 148 smaller than the grinding wheel 146 are fixed to the annular groove in the gap between the two grinding wheels 146. Therefore, the sizes of the upper surface (not shown) and the lower end surface 48a of the wear detection member 148 are typically smaller than the sizes of the upper surface (not shown) and the lower end surface 46a of the grinding wheel 46. The details of the wear detection member 148 are the same as those of the wear detection member 48 except for the points regarding the arrangement and size.

[0088] For example, the relationship between the distance from the lower end (tip) 148a of the wear detection member 148 to the lower surface 144b of the wheel base 144 and the distance from the lower end (tip) 146a of the unused grinding wheel 146 to the lower surface 144b of the wheel base 144 is the same as that of the grinding wheel 42. That is, the wear detection member 148 is configured such that the distance from the lower end 148a to the lower surface 144b of the wheel base 144 is smaller than the distance from the lower end 146a of the unused grinding wheel 146 to the lower surface 144b of the wheel base 144.

[0089] The grinding wheel 142 according to the second aspect configured as described above has the same function as the grinding wheel 42 and can be used in place of the grinding wheel 42 in the detection method of the above-described embodiment. Therefore, even when this grinding wheel 142 is used, the wear of the grinding wheel can be detected with higher accuracy than before.

[0090] FIG. 8 is a side view schematically showing the structure of a grinding wheel 242 according to a third aspect. In this FIG. 8, for convenience of explanation, cross-sections of some elements are shown. The basic structure of the grinding wheel 242 is the same as that of the grinding wheel 42. Specifically, the grinding wheel 242 includes an annular wheel base 244 having an annular upper surface (second surface) 244a and an annular lower surface (first surface) 244b opposite to the upper surface 244a.

[0091] At the lower surface 244b of the wheel base 244, the lower ends of annular grooves (not shown) extending along the circumferential direction of the wheel base 244 are open, and in these annular grooves, a plurality of rectangular parallelepiped grinding wheels 246 in which abrasive grains such as diamond are dispersed in a binder such as resin, ceramics, and metal are fixed at substantially equal intervals with gaps therebetween by an adhesive or the like.

[0092] Also, in the grinding wheel 242 according to the third aspect, as shown in FIG. 8, one or a plurality of wear detection members (members) 248 are arranged in a manner of being buried in the proximal end side of one or a plurality of grinding wheels 246. Note that the wear detection member 248 may be arranged in a manner of overlapping the proximal end side of one or a plurality of grinding wheels 246. The details of the wear detection member 248 are the same as those of the wear detection member 48 except for the points regarding the arrangement and size.

[0093] For example, the relationship between the distance from the lower end (tip) 248a of the wear detection member 248 to the lower surface 244b of the wheel base 244 and the distance from the lower end (tip) 246a of the unused grinding wheel 246 to the lower surface 244b of the wheel base 244 is the same as that in the case of the grinding wheel 42. That is, the wear detection member 248 is configured such that the distance from the lower end 248a to the lower surface 244b of the wheel base 244 is smaller than the distance from the lower end 246a of the unused grinding wheel 246 to the lower surface 244b of the wheel base 244.

[0094] The grinding wheel 242 according to the third aspect configured as described above has the same function as the grinding wheel 42 and can be used in place of the grinding wheel 42 in the detection method of the above-described embodiment. Therefore, even when this grinding wheel 242 is used, the wear of the grinding wheel can be detected with higher accuracy than before.

[0095] FIG. 9 is a side view schematically showing the structure of a grinding wheel 342 according to the fourth aspect. The basic structure of this grinding wheel 342 is the same as the structure of the grinding wheel 42. Specifically, the grinding wheel 342 includes an annular wheel base 344 having an annular upper surface (second surface) 344a and an annular lower surface (first surface) 344b opposite to the upper surface 344a.

[0096] On the lower surface 344b of the wheel base 344, the lower ends of annular grooves (not shown) along the circumferential direction of the wheel base 344 are open, and in these annular grooves, a plurality of rectangular grinding wheels 346 in which abrasive grains such as diamond are dispersed in a binder such as resin, ceramics, and metal are fixed at substantially equal intervals by an adhesive or the like with gaps between them.

[0097] Also, in the grinding wheel 342 according to the fourth aspect, as shown in FIG. 9, a groove (recess) 348b is provided on the lower end (tip) 348a side of a part (or all) of the plurality of grinding wheels 346, i.e., the grinding wheel 348. Specifically, the lower end of the groove 348b is open on the surface of the lower end 348a side of the grinding wheel 348.

[0098] Here, the groove 348b is configured such that the depth d3 from the lower end 348a of the grinding wheel 348 is shallower than the distance d4 from the lower end 348a of the unused grinding wheel 348 (or the lower end (tip) 346a of the grinding wheel 346) to the lower surface 344b of the wheel base 344. The depth (the distance from the lower end 348a to the bottom of the groove 348b) d3 is, for example, 3.0 mm or more and 19.5 mm or less, typically 6.0 mm, and the distance d4 is, for example, 3.5 mm or more and 20 mm or less, typically 7.0 mm.

[0099] Therefore, in plunge grinding where the lower end 346a of the grinding wheel 346 and the lower end 348a of the grinding wheel 348 are pressed against the upper surface (back surface 11b, etc.) of the workpiece 11, the portion corresponding to the bottom of the groove 348b comes into contact with the workpiece 11 only after the groove 348b of the grinding wheel 348 is lost. That is, when the groove 348b is lost, the total area of contact between the workpiece 11 and the grinding wheel 346 and the grinding wheel 348 increases, so the load on grinding the workpiece 11 becomes larger than when the groove 348b is not lost.

[0100] The grinding wheel 342 according to the fourth aspect configured as described above has the same functions as the grinding wheel 42 and can be used in place of the grinding wheel 342 in the detection method of the above-described embodiment. Therefore, even when this grinding wheel 342 is used, the wear of the grinding wheel can be detected with higher accuracy than in the past.

[0101] In addition, the structures, methods, etc. according to the above-described embodiments and modifications can be implemented with changes as long as they do not depart from the scope of the object of the present invention.

Explanation of Signs

[0102] 2: Grinding device 4: Base 4a: Recess 6: X-axis movement mechanism 8: Table cover 10: Dust and splash-proof cover 12: Holding table (chuck table) 14: Frame 16: Holding plate (holding surface) 16a: Upper surface 18: Support structure 20: Z-axis movement mechanism 22: Guide rail 24: Moving plate 26: Screw shaft 28: Rotation drive source 30: Support tool 32: Grinding mechanism 34: Spindle housing 36: Spindle 38: Mount 40: Fastener 42: Grinding wheel 44: Wheel base 44a: Upper surface (second surface) 44b: Lower surface (first surface) 46: Grinding stone 46a: Lower end (tip) 48: Wear detection member (member) 48a: Lower end (tip) 50: Controller (Control Unit) 50a: Grinding Control Unit 50b: Monitoring and Judgment Unit 50c: Notification Processing Unit 52: Processing Device 54: Memory Device 56: Input Device 58: Output Device (Notification Module) 142: Grinding Wheel 144: Wheel Base 144a: Upper Surface (Second Surface) 144b: Lower Surface (First Surface) 146: Grinding Stone 146a: Lower End (Tip) 148: Wear Detection Member (Member) 148a: Lower End (Tip) 242: Grinding Wheel 244: Wheel Base 244a: Upper Surface (Second Surface) 244b: Lower Surface (First Surface) 246: Grinding Stone 246a: Lower End (Tip) 248: Wear Detection Member (Member) 248a: Lower End (Tip) 342: Grinding Wheel 344: Wheel Base 344a: Upper Surface (Second Surface) 344b: Lower Surface (First Surface) 346: Grinding Stone 346a: Lower End (Tip) 348: Grinding Stone 348a: Lower End (Tip) 348b: Groove (Recessed Portion) 11: Workpiece 11a: Surface 11b: Back Surface ST1: Grinding Step ST2: Monitoring Step ST2a: Information Acquisition Step ST2b: Load Judgment Step ST3: Notification Step d1: Distance d2: Distance d3: Depth d4: Distance

Claims

1. A grinding device for grinding a workpiece, comprising: a holding table for holding the workpiece; a grinding wheel having a wheel base with an annular first surface and a grinding wheel disposed on the first surface side of the wheel base, a spindle attached to an end of the grinding wheel on the side opposite to the first surface, and a motor for rotating the spindle; a notification module for notifying information regarding the grinding mechanism; a controller including a processing device and a storage device, the controller controlling the grinding mechanism and the notification module by operating the processing device according to a program stored in the storage device; wherein: a member having a smaller distance from the first surface to the tip than the grinding wheel is disposed on the first surface side of the wheel base; the controller, according to the program, performs a process of grinding the workpiece by rotating the spindle with the motor and bringing the grinding wheel into contact with the workpiece; performs a process of monitoring the magnitude of the load applied to the rotation of the spindle when grinding the workpiece; and performs a process of notifying the notification module to that effect when the magnitude of the load deviates from a reference range. A grinding device.

2. The controller, according to the program, performs a process of monitoring the value of the current flowing through the motor as the magnitude of the load when grinding the workpiece, and performs a process of notifying the notification module to that effect when the value of the current deviates from a reference range. The grinding device according to Claim 1.

3. The grinding device according to Claim 2, wherein the member is configured such that the load when grinding the workpiece is greater than that of the grinding wheel.

4. The grinding device according to Claim 3, wherein the member is disposed on the wheel base in a manner of being buried in the proximal end side of the grinding wheel or overlapping the proximal end side of the grinding wheel.

5. A grinding device for grinding a workpiece, comprising: a holding table for holding the workpiece; a grinding wheel having a wheel base with an annular first surface and a grinding wheel disposed on the first surface side of the wheel base, a spindle attached to an end of the grinding wheel on the side opposite to the first surface, and a motor for rotating the spindle; a notification module for notifying information regarding the grinding mechanism; a controller including a processing device and a storage device, the controller controlling the grinding mechanism and the notification module by operating the processing device according to a program stored in the storage device; comprising, on the surface at the tip of the grinding wheel, a groove is opened whose depth from the tip is shallower than the distance from the first surface to the tip, the controller, according to the program, a process of grinding the workpiece by rotating the spindle with the motor and bringing the grinding wheel into contact with the workpiece, a process of monitoring the magnitude of the load applied to the rotation of the spindle when grinding the workpiece, a grinding apparatus that executes a process of notifying the notification module to that effect when the magnitude of the load deviates from a reference range.

6. the controller, according to the program, when grinding the workpiece, performs a process of monitoring the value of the current flowing through the motor as the magnitude of the load, The grinding apparatus according to claim 5, which performs a process of notifying the notification module to that effect when the value of the current deviates from a reference range.

7. The grinding apparatus according to any one of claims 1 to 6, wherein the notification module is any one of a display, an indicator light, and a speaker.

8. A detection method for detecting wear of a grinding wheel used when grinding a workpiece, a grinding step of grinding the workpiece by rotating a grinding wheel including a wheel base having an annular first surface, a grinding wheel disposed on the first surface side of the wheel base, and a member disposed on the first surface side of the wheel base and having a smaller distance from the first surface to the tip than the grinding wheel, and bringing the grinding wheel into contact with the workpiece, a monitoring step of monitoring the magnitude of the load applied to the rotation of the grinding wheel when executing the grinding step, a detection method comprising a notification step of notifying to that effect when the magnitude of the load deviates from a reference range.

9. The detection method according to claim 8, wherein the member is configured such that the load when grinding the workpiece is larger than that of the grinding wheel.

10. The detection method according to claim 9, wherein the member is disposed on the wheel base in a manner of being buried in the proximal end side of the grinding wheel or overlapping the proximal end side of the grinding wheel.

11. A detection method for detecting wear of a grinding wheel used when grinding a workpiece, A grinding wheel including a wheel base having an annular first surface and a grinding wheel disposed on the first surface side of the wheel base, and rotating the grinding wheel in which a groove having a depth from the tip shallower than the distance from the first surface to the tip is opened on the tip surface of the grinding wheel to bring the grinding wheel into contact with a workpiece to grind the workpiece; A monitoring step of monitoring the magnitude of the load applied to the rotation of the grinding wheel when executing the grinding step; A detection method comprising a notification step of notifying that the magnitude of the load is out of a reference range.

12. In the monitoring step, as the magnitude of the load, the value of the current flowing through a motor that rotates the grinding wheel is monitored; The detection method according to any one of Claims 8 to 11, wherein in the notification step, when the value of the current is out of a reference range, that fact is notified.

13. A grinding wheel used when grinding a workpiece, comprising: A wheel base having an annular first surface; A grinding wheel disposed on the first surface side of the wheel base; A member disposed on the first surface side of the wheel base and having a smaller distance from the first surface to the tip than the grinding wheel.

14. The grinding wheel according to Claim 13, wherein the member is configured such that the load when grinding the workpiece is larger than that of the grinding wheel.

15. The grinding wheel according to Claim 14, wherein the member is disposed on the wheel base in a manner of being buried in the proximal end side of the grinding wheel or overlapping the proximal end side of the grinding wheel.

Images