JP6423738B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus that grinds a workpiece formed in a rectangular shape by rotating a grinding wheel disposed in an annular shape.

  2. Description of the Related Art Conventionally, a grinding apparatus that grinds a thin plate-like rectangular workpiece cut out into a rectangular shape is known (see, for example, Patent Document 1). In grinding by this grinding apparatus, a rotating grinding wheel is brought into contact with the upper surface of the rectangular workpiece sucked and held by the chuck table. Then, the grinding with the grinding wheel is continued until the rectangular workpiece has a predetermined thickness.

  The holding surface of the chuck table is formed in a conical shape whose outer periphery is slightly lowered with the center of rotation of the chuck table as a vertex. When the rectangular workpiece is sucked and held on the holding surface, the rectangular workpiece also has a conical shape along the holding surface, and the grinding wheel comes into contact with the rectangular workpiece and grinds in the range from the apex of the cone to the outer periphery.

Japanese Patent No. 5230982

  In the above grinding, since the rectangular workpiece rotates at the center position passing through the apex of the cone, the contact area of the grinding wheel that contacts the rectangular workpiece during grinding becomes wider or narrower. Due to this difference, the grinding load on the rectangular workpiece also changes.When the contact area of the grinding wheel is wide, the grinding load increases and the grinding force decreases.When the contact area of the grinding wheel is narrow, the grinding load decreases and the grinding force decreases. To rise. As described above, since the grinding force is changed, there is a problem that the thickness of the rectangular workpiece varies depending on the change.

  This invention is made | formed in view of this point, and it aims at providing the grinding apparatus which can make the thickness of the rectangular workpiece | work ground to be uniform.

  The grinding apparatus of the present invention includes a holding means for holding a rectangular work, a grinding means for rotatably mounting a grinding wheel having a grinding wheel arranged in an annular shape, and grinding a rectangular work held by the holding means, and a holding means And a grinding feed means for moving the grinding means relative to and away from each other, the holding means includes a chuck table having a conical holding surface for holding a rectangular workpiece, and a cone A chuck table rotating means for rotating the chuck table with the axis passing through the apex of the holding surface of the shape as a rotation axis, and a chuck table rotation angle recognizing unit for recognizing the rotation angle of the chuck table rotated by the chuck table rotating means, The grinding means includes a grinding wheel rotating unit that rotates about the center of the grinding wheel, and a rotation speed of the grinding wheel that rotates at the grinding wheel rotating unit. A rotation speed adjustment section that variably adjusts, and the rotation speed adjustment section uses the recognition result of the chuck table rotation angle recognition section to rotate the rotation speed of the grinding wheel faster when the contact area between the rectangular workpiece and the grinding wheel is large. When the contact area between the rectangular workpiece and the grinding wheel is small, the rotation speed of the grinding wheel is rotated slowly.

  According to this configuration, the rotational speed of the grinding wheel is adjusted by the rotational speed adjustment unit in accordance with the change in the contact area where the grinding wheel contacts the rectangular workpiece, so that the grinding force of the rectangular workpiece by the grinding wheel can be kept constant. it can. Thereby, the thickness of the rectangular workpiece to be ground can be made uniform.

  According to the present invention, since the rotational speed of the grinding wheel is adjusted according to the change in the contact area between the grinding wheel and the rectangular workpiece, the thickness of the rectangular workpiece to be ground can be made uniform.

It is a perspective view of the grinding device concerning this embodiment. It is a schematic sectional drawing of the grinding means and chuck table which concern on this Embodiment. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on this Embodiment. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on this Embodiment. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on a modification. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on a modification. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on another modification. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on another modification. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on another modification. It is an explanatory top view which shows the grinding point of the rectangular workpiece | work which concerns on another modification.

  Hereinafter, the grinding apparatus according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a grinding apparatus according to the present embodiment. Note that the grinding apparatus according to the present embodiment is not limited to the apparatus configuration dedicated to the grinding process as shown in FIG. 1, and for example, a series of processes such as a grinding process, a polishing process, and a cleaning process are performed fully automatically. It may be incorporated into a fully automatic type processing apparatus. In the following drawings, for convenience of explanation, the description of a BG (Back-Grinding) tape is omitted.

  As shown in FIG. 1, the grinding apparatus 1 uses a grinding wheel 46 in which a large number of grinding wheels 48 are arranged in an annular shape so as to grind a rectangular workpiece W held on the chuck table 21 of the holding means 20. It is configured. In the grinding apparatus 1, the rotation axis of the chuck table 21 and the rotation axis of the grinding wheel 46 are not coaxial and are arranged at different positions in a direction perpendicular to the rotation axis of the grinding wheel 46, and the grinding wheels 48 arranged in an annular shape are rectangular. By passing through the center of the upper surface 81 of the workpiece W, the grinding wheel 48 is brought into contact with the rectangular workpiece W in an arc shape to be cut and thinned. In addition, the rectangular workpiece W should just be a plate-shaped object formed in the planar shape used as a square or a rectangular rectangle. Accordingly, the rectangular workpiece W is formed by molding a hard plate-like workpiece such as sapphire or silicon carbide, a semiconductor substrate such as silicon or gallium arsenide, a substrate formed of resin or metal, and the upper surface 81 side thereof with a resin such as epoxy. It may be a work. In the present embodiment, the rectangular workpiece W is formed in a square planar shape.

  A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 11 of the grinding apparatus 1, and this opening is covered with a movable plate 12 that can move together with the chuck table 21 and a bellows-shaped waterproof cover 13. ing. Below the waterproof cover 13, ball screw type advance / retreat means (not shown) for moving the chuck table 21 in the X-axis direction is provided.

  On the surface of the chuck table 21, a holding surface 23 for adsorbing the rectangular workpiece W is formed by a porous porous material. The holding surface 23 is formed in a planar shape that is rectangular (square) corresponding to the rectangular workpiece W. Although the holding surface 23 is drawn flat in FIG. 1, the actual holding surface 23 has a gently inclined cone shape with the rotation center of the chuck table 21 as a vertex, and the rectangular workpiece W also has a conical shape along the holding surface 23. (See FIG. 2). The holding surface 23 is connected to a suction source (not shown) through a flow path in the chuck table 21, and the rectangular workpiece W is sucked and held by the negative pressure generated on the holding surface 23.

  The holding unit 20 includes a chuck table rotating unit 22 that continuously rotates the chuck table 21. The rotation center position of the chuck table rotating means 22 is set to an axial position passing through the conical apex of the holding surface 23. The holding unit 20 further includes a chuck table rotation angle recognition unit 24 provided below the chuck table rotation unit 22. The chuck table rotation angle recognition unit 24 includes a rotary encoder or the like, and recognizes the rotation angle of the chuck table 21 rotated by the chuck table rotation means 22.

  The column 14 on the base 11 is provided with a grinding feed means 31 for moving the grinding means 41 and the chuck table 21 in a direction relatively approaching and separating from the grinding feed direction (Z-axis direction). The grinding feed means 31 has a pair of guide rails 32 arranged in the column 14 and parallel to the Z-axis direction, and a motor-driven Z-axis table 33 slidably installed on the pair of guide rails 32. . Nut portions (not shown) are formed on the back side of the Z-axis table 33, and a ball screw 34 is screwed to these nut portions. The ball screw 34 is rotationally driven by a drive motor 35 connected to one end of the ball screw 34, whereby the grinding means 41 is moved along the guide rail 32 in the Z-axis direction.

  The grinding means 41 is attached to the front surface of the Z-axis table 33 via a housing 42, and is configured by providing a mount 44 at the lower end of a grinding wheel rotating portion 43 including a motor and the like. The grinding wheel rotating portion 43 is provided with a flange 45, and the grinding means 41 is supported on the housing 42 via the flange 45. On the lower surface of the mount 44, a grinding wheel 46 in which a plurality of grinding wheels 48 are arranged in a circular shape on a wheel base 47 is rotatably mounted. The grinding wheel 46 is rotated by driving the grinding wheel rotating unit 43. The plurality of grinding wheels 48 are constituted by, for example, segment grindstones in which diamond abrasive grains are hardened with a bonding agent such as metal bond.

  Further, the grinding apparatus 1 is provided with a control means 61 that controls each part of the apparatus. The control unit 61 includes a processor that executes various processes, a memory, and the like. The memory is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application. The control means 61 controls the drive timing and drive amount of each part of the grinding apparatus 1 according to various conditions stored in advance and output results from various detection means constituting the grinding apparatus 1. For example, the control means 61 calculates and recognizes the area of the contact area A (see FIG. 3A) where the grinding wheel 48 contacts the rectangular workpiece W based on the detection result of the chuck table rotation angle recognition unit 24. 62. In the calculation in the contact area recognizing unit 62, in addition to the detection result of the chuck table rotation angle recognizing unit 24, a contact region having an arc shape is obtained from various conditions such as the size of the rectangular workpiece W and the size of the grinding wheel 48 stored in advance. The area of A is obtained. For example, the correspondence between the rotation angle of the chuck table 21 and the area of the contact area A is stored in advance as data for each shape of the rectangular workpiece W, and the chuck table rotation angle recognition unit 24 detects the data by referring to this data. For the result, the area of the contact region A may be obtained.

  Further, the control means 61 has a rotation speed adjustment unit 63 that variably adjusts the rotation speed of the grinding wheel 46 rotated by the grinding wheel rotation unit 43. For example, the rotation speed adjustment unit 63 calculates the rotation speed of the grinding wheel 46 using the recognition result of the area of the contact area A recognized by the contact area recognition unit 62. Furthermore, the rotation speed adjustment unit 63 outputs a predetermined signal to the grinding wheel rotation unit 43 based on the calculated rotation speed of the grinding wheel 46 to adjust the rotation speed of the grinding wheel 46. The rotation speed adjustment unit 63 is also configured as a part of the grinding means 41.

  Here, in the control means 61, it is also conceivable that the contact area recognition unit 62 is omitted. In this case, the rotation speed adjustment unit 63 calculates the rotation speed of the grinding wheel 46 based on the recognition result of the rotation angle of the chuck table 21 recognized by the chuck table rotation angle recognition unit 24. For example, the correspondence between the rotation angle of the chuck table 21 and the rotation speed of the grinding wheel 46 is stored in advance as data for each shape of the rectangular workpiece W, and the chuck table rotation angle recognition unit 24 refers to this data. You may obtain | require the rotational speed of the grinding wheel 46 with respect to a recognition result.

  FIG. 2 is a schematic sectional view of the grinding means and the chuck table according to the present embodiment. As shown in FIG. 2, when the rectangular workpiece W is ground, the rectangular workpiece W is first held on the chuck table 21. Since the holding surface 23 of the chuck table 21 has a gently inclined conical shape with the rotation center as a vertex, the rectangular workpiece W is also held conically along the holding surface 23. After the tilt of the chuck table 21 is adjusted so that the upper surface 81 of the conical rectangular workpiece W is parallel to the grinding surface of the grinding wheel 48, the grinding wheel 48 and the rectangular workpiece W rotate while supplying grinding water. Grinding by contact. During grinding, the thickness of the wafer W is measured in real time by a thickness measuring means (not shown), and the feed amount of the grinding means 41 is controlled based on the measurement result of the thickness measuring means.

  FIG. 3A is an explanatory plan view showing a grinding procedure for a rectangular workpiece. As shown in FIG. 3A, in the grinding process of the rectangular workpiece W in the present embodiment, the relative positional relationship between the rectangular workpiece W held on the chuck table 21 and the grinding wheel 48 is such that the outer peripheral edge of the grinding wheel 48 is a rectangular workpiece. The state of passing through the rotation center of W is maintained. Further, since the rectangular workpiece W is held in a conical shape, the contact area A of the grinding wheel 48 with respect to the rectangular workpiece W is indicated by a halftone dot in the figure. This contact area A has a belt-like shape extending in an arc along the outer edge of the grinding wheel 48, and is a point C serving as the center of rotation of the rectangular workpiece W, and on the outer periphery of the rectangular workpiece W above this point C in FIG. Between the intersecting positions. In FIG. 3A, the diameter of the grinding wheel 48 is larger than the length of one side of the rectangular workpiece W.

  FIGS. 3B to 3D and FIGS. 4A to 4C are explanatory plan views showing a grinding procedure of the rectangular workpiece of FIG. 3A, and are explanatory diagrams of contact areas of the rectangular workpiece and the grinding wheel. As can be understood by comparing these drawings, during grinding, the area (contact area) of the contact area A of the grinding wheel 48 with respect to the rectangular workpiece W becomes wider or narrower due to the rotation of the rectangular workpiece W. Will change. 3B, the center in the width direction of the contact area A passes through the midpoint N of one side of the rectangular workpiece W. In FIG. 3C, the outer periphery of the contact area A passes through the midpoint N. In FIG. The inner circumference passes through the midpoint N. In this Embodiment, when calculating | requiring the relative position of the rectangular workpiece | work W and the grinding wheel 48 in which the area of the contact area A becomes the minimum, the area of the contact area A in each state of FIGS. 3B-3D is simulated. Then, by comparing them, the passing position of the contact area A with respect to the middle point N when the area of the contact area A is minimized is determined. In this comparison, the area of the contact region A in the present embodiment is minimized when the center in the width direction of the contact region A shown in FIG. 4A, the center in the width direction of the contact area A passes through the corner CN of the rectangular workpiece W. In FIG. 4B, the outer periphery of the contact area A passes through the corner CN. In FIG. 4C, the inner circumference of the contact area A is an angle. Passing CN. In this Embodiment, when calculating | requiring the relative position of the rectangular workpiece | work W and the grinding wheel 48 in which the area of the contact area A becomes the maximum, the area of the contact area A in each state of FIGS. 4A-4C is simulated. Then, by comparing them, the passing position of the contact area A with respect to the corner CN when the area of the contact area A is maximized is determined. In this comparison, the area of the contact region A in the present embodiment is maximized when the outer periphery of the contact region A shown in FIG. 4B passes through the corner CN. Such a calculation may be performed in the control means 61 or may be performed by an external device of the grinding apparatus 1.

  Here, if the rotation speed of the chuck table 21 is made constant as in the prior art, the grinding load becomes larger and the grinding becomes difficult when the area of the relatively large contact area A is smaller than the narrower one. For this reason, the contact area of the grinding wheel 48 with respect to the rectangular workpiece W changes according to the rotation angle of the chuck table 21 and the rectangular workpiece W, and the thickness variation of the rectangular workpiece W increases as the contact area increases. Will occur. Specifically, in the rectangular workpiece W, the thickness of the portion corresponding to the contact area A in FIG. 3B is minimized, and the thickness of the portion corresponding to the contact area A in FIG. 4B is maximized.

  Returning to the description of the present embodiment, in the present embodiment, control for accelerating and decelerating the rotational speed of the grinding wheel 46 rotating by the grinding wheel rotating unit 43 is performed in accordance with the change in the area of the contact region A. In this control, during the grinding of the rectangular workpiece W, the rotation angle of the chuck table 21 rotated by the chuck table rotating means 22 is recognized by the chuck table rotation angle recognition unit 24, and the recognition result is output to the contact area recognition unit 62. The The contact area recognition unit 62 calculates and recognizes the area of the contact area A from the recognized rotation angle of the chuck table 21 (see FIG. 1). The recognition result of the area of the contact area A is output to the rotation speed adjustment unit 63, and the rotation speed of the grinding wheel 46 is calculated according to the change in the area of the contact area A. The rotation speed by this calculation is set to be fast when the area of the contact area A is wide and slow when the area of the contact area A is narrow. Then, a signal for controlling the rotation speed is output from the rotation speed adjusting unit 63 to the grinding wheel rotating unit 43. Thereby, the rotation speed adjusting unit 63 rotates the grinding wheel 46 faster when the area of the contact area A is wider, and rotates the grinding wheel 46 slower when the area of the contact area A is smaller.

  Here, as an example of the control of the rotation speed adjusting unit 63, the following control can be cited. From the recognition result of the chuck table rotation angle recognition unit 24, the contact area A is as shown in FIG. 4B, that is, the timing at which the outer periphery of the grinding wheel 48 passes the corner CN of the rectangular workpiece W is recognized, and the grinding wheel is detected at that timing. The rotational speed of 46 is controlled to the highest speed. On the other hand, the contact area A is as shown in FIG. 3B, that is, the timing when the center of the grinding wheel 48 in the width direction passes the midpoint N of one side of the rectangular workpiece W is recognized, and the grinding wheel 46 reaches the lowest speed at that timing. Control the rotation speed. Also in such control, the rotational speed of the grinding wheel 46 is adjusted to be fast when the area of the contact area A is wide and slow when the area of the contact area A is narrow.

  When the contact area recognition unit 62 calculates the area of the contact area A, the rotation speed adjustment unit 63 compares the area of the contact area A with a predetermined threshold value, and is greater than (or wider than) the threshold value. For example, the first rotation speed may be set, and if it is less than the threshold value (or less than the threshold value), the second rotation speed may be set relatively slower than the first rotation speed. In this case, the threshold value can be arbitrarily set according to various conditions, but may be an average value of the area of the contact region A or an intermediate value between the maximum value and the minimum value of the contact region A. .

  As described above, in the grinding apparatus 1 according to the present embodiment, when the rotating rectangular workpiece W is ground, even if the contact area between the grinding wheel 48 and the rectangular workpiece W changes without being constant, this change occurs. The rotational speed of the grinding wheel 46 can be accelerated or decelerated so as to follow the above. Thereby, even if the area of the contact area A changes like the rectangular workpiece W, the grinding force of the rectangular workpiece W by the grinding wheel 48 can be maintained constant, and the thickness of the rectangular workpiece W can be uniformly ground. it can.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, direction, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, as shown in FIG. 5A, the diameter of the grinding wheel 48 may be smaller than the length of one side of a square rectangular work W. In this case, the diameter of the grinding wheel 48 may be equal to or greater than the distance from the center C of the rectangular workpiece W to the corner CN. 5B, the center in the width direction of the contact area A passes through the midpoint N of one side of the rectangular workpiece W. In FIG. 5C, the outer periphery of the contact area A passes through the midpoint N. In FIG. The inner circumference passes through the midpoint N. In this case, in order to obtain the relative position between the rectangular workpiece W and the grinding wheel 48 that minimizes the area of the contact area A, the area of the contact area A in each state of FIGS. 5B to 5D is simulated. Then, by comparing them, the passing position of the contact area A with respect to the middle point N when the area of the contact area A is minimized is determined. In such a comparison, the area of the contact region A is minimized when the center in the width direction of the contact region A shown in FIG.

  In FIG. 6A, the outer periphery of the contact area A passes so as to contact without intersecting the side of the rectangular workpiece W, and in FIG. 6B, the outer periphery of the contact area A passes through the corner CN. In this case, the area of the contact area A is maximized. When the relative position between the rectangular workpiece W and the grinding wheel 48 is obtained, the area of the contact region A in each state of FIGS. 6A and 6B is simulated. Then, they are compared to determine in which state the area of the contact region A is maximized. In such a comparison, the area of the contact area A is maximized when the outer periphery of the contact area A shown in FIG.

  Further, the rectangular workpiece W may have a rectangular planar shape. Even in this case, the rotation angle of the chuck table 21 may be recognized, and the rotation speed of the grinding wheel 46 may be variably adjusted according to the recognition result.

  In this way, the rectangular workpiece W may be rectangular, and the diameter dimension of the grinding wheel 48 may be smaller than the length of the long side of the rectangular workpiece W as shown in FIG. 7A. In this case, the diameter of the grinding wheel 48 may be equal to or greater than the distance from the center C of the rectangular workpiece W to the corner CN. 7B, the center in the width direction of the contact area A passes through the midpoint N of the long side of the rectangular workpiece W. In FIG. 7C, the outer periphery of the contact area A passes through the midpoint N. In FIG. Is passing through the middle point N. In this case, in order to obtain the relative position between the rectangular workpiece W and the grinding wheel 48 that minimizes the area of the contact area A, the area of the contact area A in each state of FIGS. 7B to 7D is simulated. Then, by comparing them, the passing position of the contact area A with respect to the middle point N when the area of the contact area A is minimized is determined. In such a comparison, the area of the contact region A is minimized when the center in the width direction of the contact region A shown in FIG.

  8A, the center in the width direction of the contact area A passes through the corner CN1 of the rectangular workpiece W. In FIG. 8B, the outer periphery of the contact area A passes through the corner CN1, and in FIG. 8C, the inner circumference of the contact area A is an angle. Passing CN1. 8D to 8F, a corner CN2 through which the contact region A passes is a corner adjacent to the corner CN1 across the side. In FIG. 8D, the center in the width direction of the contact region A represents the corner CN2 of the rectangular workpiece W. 8E, the outer periphery of the contact area A passes through the corner CN2, and in FIG. 8F, the inner periphery of the contact area A passes through the corner CN2. In this case, when the relative position between the rectangular workpiece W and the grinding wheel 48 in which the area of the contact area A is maximum is obtained, the area of the contact area A in each state of FIGS. 8A to 8F is simulated. Then, by comparing them, the passing position of the contact area A with respect to the corners CN1 and CN2 when the area of the contact area A is maximized is determined. In this comparison, the area of the contact area A is maximized when the center in the width direction of the contact area A shown in FIG. 8A passes through the corner CN1 of the rectangular workpiece W. That is, when the rectangular workpiece W is rectangular, the time when the outer periphery of the grinding wheel 48 contacts the side of the rectangular workpiece W is not maximized as in the case of a square.

  Further, as shown in FIG. 9A, the rectangular workpiece W may be a rectangle, and the diameter dimension of the grinding wheel 48 may be larger than the length of the long side of the rectangular workpiece W. 9B, the center in the width direction of the contact area A passes through the midpoint N of the long side of the rectangular workpiece W. In FIG. 9C, the outer periphery of the contact area A passes through the midpoint N. In FIG. Is passing through the middle point N. Even in this case, in order to obtain the relative position between the rectangular workpiece W and the grinding wheel 48 where the area of the contact area A is minimized, the area of the contact area A in each state of FIGS. 9B to 9D is simulated. Then, by comparing them, the passing position of the contact area A with respect to the middle point N when the area of the contact area A is minimized is determined. In this comparison, the area of the contact area A is minimized when the center in the width direction of the contact area A shown in FIG.

  10A, the center in the width direction of the contact area A passes through the corner CN1 of the rectangular workpiece W. In FIG. 10B, the outer periphery of the contact area A passes through the corner CN1, and in FIG. 10C, the inner circumference of the contact area A is an angle. Passing CN1. 10D to 10F, a corner CN2 through which the contact region A passes is a corner adjacent to the corner CN1 across the side. In FIG. 10D, the center in the width direction of the contact region A represents the corner CN2 of the rectangular workpiece W. In FIG. 10E, the outer periphery of the contact area A passes through the corner CN2, and in FIG. 10F, the inner periphery of the contact area A passes through the corner CN2. In this case, when the relative position between the rectangular workpiece W and the grinding wheel 48 in which the area of the contact area A is maximum is obtained, the area of the contact area A in each state of FIGS. 10A to 10F is simulated. Then, by comparing them, the passing position of the contact area A with respect to the corners CN1 and CN2 when the area of the contact area A is maximized is determined. In this comparison, the area of the contact area A is maximized when the outer periphery of the contact area A shown in FIG. 10E passes through the corner CN2 of the rectangular workpiece W.

  In the rectangular rectangular workpiece W, the rotation speed of the grinding wheel 46 is high when the area of the contact area A is large as described above, and the rotation speed of the grinding wheel 46 is rotated slowly when the area of the contact area A is small. The rotation speed adjustment unit 63 controls the rotation. In this control, the timing at which the grinding wheel 48 passes the outer periphery of the rectangular workpiece W described above is recognized from the recognition result of the chuck table rotation angle recognition unit 24, and the rotational speed of the grinding wheel 46 is set to the highest or lowest speed at that timing. The speed may be controlled. Further, the contact area recognition unit 62 may calculate the area of the contact region A, and the calculation result may be compared in the same manner as in the above embodiment to set the rotation speed of the grinding wheel 46.

  As described above, the present invention is useful for a grinding apparatus that grinds a workpiece having a rectangular planar shape held by a conical holding surface.

DESCRIPTION OF SYMBOLS 1 Grinding device 20 Holding means 21 Chuck table 22 Chuck table rotation means 23 Holding surface 24 Chuck table rotation angle recognition part 31 Grinding feed means 41 Grinding means 43 Grinding wheel rotation part 46 Grinding wheel 48 Grinding wheel 63 Rotational speed adjustment part W Rectangular workpiece

Claims (1)

A holding means for holding a rectangular work, a grinding means for rotatably mounting a grinding wheel in which a grinding wheel is annularly arranged, and grinding the rectangular work held by the holding means, the holding means and the grinding means A grinding feed unit that moves in a direction toward and away from each other,
The holding means includes a chuck table having a conical holding surface for holding the rectangular workpiece, a chuck table rotating means for rotating the chuck table about an axis passing through the apex of the conical holding surface, A chuck table rotation angle recognition unit for recognizing the rotation angle of the chuck table rotated by the chuck table rotation means,
The grinding means includes a grinding wheel rotating unit that rotates about the center of the grinding wheel, and a rotation speed adjusting unit that variably adjusts the rotation speed of the grinding wheel that rotates at the grinding wheel rotating unit,
The rotation speed adjustment unit uses the recognition result of the chuck table rotation angle recognition unit, and when the contact area between the rectangular workpiece and the grinding wheel is wide, rotates the rotation speed of the grinding wheel faster, and A grinding device that rotates the grinding wheel at a low speed when the contact area of the grindstone is small.

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