Grinding wheel dressing device and method

Abstract

To provide a grinding wheel modifying device and method capable of suppressing the occurrence of chatter shape on a circumferential face of a grinding wheel.SOLUTION: A grinding wheel modifying device 10 includes a modification tool T which is supported so as to permit rotative driving and is relatively moved in a rotative axis direction of a grinding wheel G which is rotatively driven and, thereby, modifies a circumferential face of the grinding wheel, and a control device CR which controls rotational frequency of the grinding wheel and controls relative movement of the modifying tool and the grinding wheel. The control device relatively moves the modifying tool and the grinding wheel while changing the rotational frequency of the grinding wheel and, thereby, performs rough modification of the circumferential face of the grinding wheel by means of the modifying tool. Further, the control device relatively moves the modifying tool and the grinding wheel while keeping rotative frequency of the grinding wheel constant and, thereby, performs precise modification of the circumferential face of the grinding wheel with the modifying tool.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for dressing a grinding wheel. [Background technology]

[0002] The grinding wheels of the grinding machine are adjusted, i.e., trued and dressed, by a grinding wheel adjustment device. The grinding wheel adjustment device includes a vertical grinding wheel adjustment device equipped with a cup-shaped adjustment tool having a rotation axis arranged perpendicular to the rotation axis of the grinding wheel shaft of the grinding wheel. There is also a horizontal grinding wheel adjustment device equipped with a disk-shaped adjustment tool having a rotation axis arranged parallel to the rotation axis of the grinding wheel shaft of the grinding wheel. The adjustment tool has diamond electroplated on its circumferential surface, and the circumferential surface of the rotating adjustment tool adjusts the circumferential surface of the rotating grinding wheel.

[0003] In such grinding wheel dressing devices, chatter marks may occur on the circumferential surface of the grinding wheel after dressing. If grinding is performed with a grinding wheel that has chatter marks, there is a risk that poor roundness or straightness may occur in the workpiece. Conventionally, this has been addressed by replacing the dressing tool or dressing tool shaft, but this is costly. In addition, this has been addressed by changing the dressing conditions (reducing the amount of cut or reducing the number of dressings, etc.), but it is difficult and time-consuming to find the dressing conditions.

[0004] In response to this, Patent Documents 1 and 2 describe a grinding wheel dressing device that can suppress the occurrence of chatter patterns on the circumferential surface of the grinding wheel by dressing the grinding wheel by varying the relative rotation speed between the dressing tool and the grinding wheel around a rotation speed at which the relative rotation speeds are constant. With this grinding wheel dressing device, there is no need to replace the dressing tool or dressing tool shaft as in the past, which reduces costs, and there is no need to change the dressing conditions (reducing the amount of cut or reducing the number of dressings, etc.), which saves the effort of finding the dressing conditions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 64-64777 [Patent Document 2] JP 2008-149440 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the inventors of the present application performed grinding wheel correction by varying the relative rotation speed of the correction tool and the grinding wheel, chatter shapes still occurred on the peripheral surface of the grinding wheel. It was found that the cause of this is that in the case of a vertical grinding wheel correction device, when the natural frequency in the direction of the rotation axis of the correction tool becomes an integer multiple of the rotation frequency (rotation speed) of the grinding wheel, resonance occurs, and this integer peak occurs on the peripheral surface of the grinding wheel, resulting in a chatter shape. It was also found that in the case of a grinding wheel correction device for a horizontal grinding wheel, when the natural frequency in the direction perpendicular to the rotation axis of the correction tool becomes an integer multiple of the rotation frequency (rotation speed) of the grinding wheel, resonance occurs, and this integer peak occurs on the peripheral surface of the grinding wheel, resulting in a chatter shape.

[0007] In order to suppress the occurrence of chattering on the peripheral surface of the grinding wheel, the rotational frequency of the grinding wheel should be set so that the natural frequency of the dressing tool is not an integer multiple of the rotational frequency of the grinding wheel. However, the rotating shaft of the dressing tool is supported by a rolling bearing, and the natural frequency of the dressing tool changes due to wear of the rolling elements, inner ring, outer ring, etc., deterioration of the lubricating oil, etc. If this change occurs, there is a risk that the set rotational frequency of the grinding wheel will not be able to suppress the occurrence of chattering on the peripheral surface of the grinding wheel.

[0008] An object of the present invention is to provide an apparatus and method for dressing a grinding wheel that can suppress the occurrence of chatter patterns on the peripheral surface of the grinding wheel. [Means for solving the problem]

[0009] The grinding wheel dressing device of the present invention is a grinding wheel dressing device comprising a dressing tool that is supported so as to be rotatably driven and that dresses the peripheral surface of the grinding wheel by moving relatively in the direction of the rotation axis of the rotationally driven grinding wheel, and a control device that controls the rotational frequency of the grinding wheel and also controls the relative movement of the dressing tool and the grinding wheel, wherein the control device performs coarse dressing of the peripheral surface of the grinding wheel with the dressing tool by moving the dressing tool and the grinding wheel relatively while varying the rotational frequency of the grinding wheel, and performs fine dressing of the peripheral surface of the grinding wheel with the dressing tool by moving the dressing tool and the grinding wheel relatively while keeping the rotational frequency of the grinding wheel constant.

[0010] In this grinding wheel dressing device, first, rough dressing is performed while varying the rotation frequency of the grinding wheel, so the number of peaks that will become chatter shapes is not constant, but the peaks are formed with a shift. Next, fine dressing is performed while keeping the rotation frequency of the grinding wheel constant, so the peaks remaining after rough dressing can be almost completely removed. Therefore, the occurrence of chatter shapes on the peripheral surface of the grinding wheel can be suppressed.

[0011] The grinding wheel dressing method according to the present invention is a grinding wheel dressing method for dressing the peripheral surface of a grinding wheel that is driven to rotate by a dressing tool that is driven to rotate, and includes a rough dressing step of performing rough dressing of the peripheral surface of the grinding wheel by the dressing tool by moving the dressing tool and the grinding wheel relatively while varying the rotation frequency of the grinding wheel, and a fine dressing step of performing fine dressing of the peripheral surface of the grinding wheel by moving the dressing tool and the grinding wheel relatively while keeping the rotation frequency of the grinding wheel constant. This provides the same effect as the grinding wheel dressing device. [Brief description of the drawings]

[0012] [Figure 1] 1 is a plan view showing a grinding machine to which a grinding wheel dressing device is applied; [Diagram 2] FIG. 2 is a partial cross-sectional view showing the grinding wheel dressing device, the grinding head, and the control device. [Diagram 3] FIG. 13 is a diagram showing the relationship between the grinding wheel rotation frequency and elapsed time during grinding wheel dressing operation. [Figure 4A]FIG. 13 is a diagram showing a state in which a correction tool and a grinding wheel are positioned at a correction start position in one pass of a grinding wheel correction operation. [Figure 4B] FIG. 13 is a diagram showing the state in which the grinding wheel has been completely dressed by a dressing tool in one pass of the grinding wheel dressing operation. [Figure 4C] FIG. 13 is a diagram showing a state in which the grinding wheel is moved in the X-axis direction relative to the dressing tool during one pass of the grinding wheel dressing operation. [Figure 4D] FIG. 13 is a diagram showing a state in which a correction tool is moved in the Z-axis direction relative to the grinding wheel during one pass of the grinding wheel correction operation. [Figure 5A] 4 is a flowchart showing a first half of a control process of a grinding wheel dressing device in a grinding apparatus. [Figure 5B] 10 is a flowchart showing a second half of the control process of the grinding wheel dressing device in the grinding apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (1. Configuration of Grinding Apparatus 1) The grinding wheel dressing device of this embodiment is provided in a grinding machine that performs cylindrical grinding, for example. As shown in Fig. 1, the grinding machine 1 includes a bed 2 that constitutes a base portion, a grinding wheel head 3 that is placed on the bed 2 and supports a grinding wheel G so that the grinding wheel G can be rotated, an X-axis drive unit 4 that moves the grinding wheel head 3 in the X-axis direction, and a work table 5 that is placed on the bed 2 at a position different from the grinding wheel head 3.

[0014] Furthermore, the system is equipped with a headstock 7 and a tailstock 8 having a spindle 6 that is placed on the work table 5 and supports the work W and rotates the work W, a Z-axis drive unit 9 that moves the work table 5 in the Z-axis direction, a grinding wheel dressing device 10 that is provided on the headstock 7 and supports a dressing tool T for dressing the grinding wheel G so that it can be rotatably driven, and a control device CR. The X-axis drive unit 4 and the Z-axis drive unit 9 are known drive units that are each configured using a servo motor, a feed screw, etc.

[0015] The grinding wheel head 3 includes a grinding wheel spindle GA on which a grinding wheel G is attached, and a grinding wheel spindle drive device GM consisting of a motor or the like for driving the grinding wheel spindle GA to rotate. The grinding wheel G is formed into a disk shape using an appropriate grinding wheel material such as CBN grinding wheel so that the outer circumferential surface and an end face in the vicinity of the outer circumferential surface become the grinding surfaces, and is driven to rotate together with the grinding wheel spindle GA by the grinding wheel spindle drive device GM. The headstock 7 includes a spindle drive device 16 consisting of a motor or the like for driving the spindle 6 to rotate.

[0016] The grinding wheel dressing device 10, which will be described in detail later, includes a dressing tool shaft TA to which a dressing tool T is attached, and a dressing tool shaft drive device TM consisting of a built-in motor or the like for driving the dressing tool shaft TA to rotate. The dressing tool T is formed in a cup shape with diamond electroplated on its outer circumferential surface, and is driven to rotate together with the dressing tool shaft TA by the dressing tool shaft drive device TM.

[0017] The control device CR drives and controls the X-axis drive device 4 to move the wheel head 3 in the X-axis direction, and drives and controls the Z-axis drive device 9 to move the work table 5 in the Z-axis direction. It also drives and controls the main spindle drive device 16 to rotate the workpiece W, drives and controls the grinding wheel spindle drive device GM to rotate the grinding wheel G, and drives and controls the correction tool spindle drive device TM to rotate the correction tool T.

[0018] (2. Detailed configuration of the grinding wheel dressing device 10) As shown in Fig. 2, the grinding wheel dressing device 10 includes a dressing tool T, a dressing tool shaft TA, a dressing tool shaft drive device TM, a housing TH, and bearings TB1 and TB2. The grinding wheel dressing device 10 is a vertical grinding wheel dressing device including a cup-shaped dressing tool T having a rotation axis TL arranged perpendicular to the rotation axis GL of the grinding wheel shaft GA of the grinding wheel G. The dressing tool T has diamond D electroplated on its outer circumferential surface, and a coaxial, approximately cylindrical dressing tool shaft TA is attached to one end face side. The dressing tool shaft drive device TM rotates the dressing tool T together with the dressing tool shaft TA, and the outer circumferential surface of the dressing tool T dresses the surface condition of the outer circumferential surface of the grinding wheel G, i.e., performs at least one of truing and dressing.

[0019] Truing here refers to a shaping operation, such as shaping the grinding wheel G to fit the shape of the workpiece W when the grinding wheel G has worn down due to grinding, or removing runout of the grinding wheel G due to uneven wear. Dressing refers to a dressing operation, such as adjusting the amount of protrusion of the abrasive grains and creating the cutting edges of the abrasive grains. Dressing is an operation to correct dulling, clogging, and overflow, and is usually performed after truing. Truing and dressing may also be performed without any particular distinction.

[0020] The housing TH includes a disk-shaped housing cap 11, a cylindrical first housing 12, and a cylindrical second housing 13. The housing cap 11 is attached to the front end of the first housing 12. The second housing 13 is attached to the rear end of the first housing 12. The housing cap 11 and the housings 12, 13 are connected and fixed together by, for example, bolts.

[0021] The correction tool shaft TA is arranged in the housing TH so as to be rotatable around the rotation axis TL relative to the housing TH. A bearing TB1 is arranged on the housing cap 11 side of the correction tool shaft TA. The inner peripheral surface of the inner ring of the bearing TB1 is supported on the outer peripheral surface of the correction tool shaft TA, and the outer peripheral surface of the outer ring of the bearing TB1 is supported on the inner peripheral surface of the first housing 12. As a result, the housing cap 11 side of the correction tool shaft TA is rotatably supported on the housing TH via the bearing TB1. The bearing TB1 is a rolling bearing, and is a known parallel combination type angular ball bearing. Lubricating oil is supplied to the bearing TB1 through an oil passage (not shown) provided in the housing TH. However, the bearing TB1 may be another type of bearing depending on the conditions of use.

[0022] A bearing TB2 is disposed on the second housing 13 side of the correction tool shaft TA. The inner peripheral surface of the inner ring of the bearing TB2 is supported on the outer peripheral surface of the correction tool shaft TA, and the outer peripheral surface of the outer ring of the bearing TB2 is supported on the inner peripheral surface of the second housing 13. As a result, the second housing 13 side of the correction tool shaft TA is rotatably supported on the housing TH via the bearing TB2. The bearing TB2 is a rolling bearing, and is one well-known cylindrical roller bearing. Lubricating oil is supplied to the bearing TB2 through an oil passage (not shown) provided in the housing TH. However, the bearing TB2 may be another type of bearing depending on the conditions of use.

[0023] An inner peripheral surface of a rotor 14 constituting the corrected tool axis driving device TM is fixed between the bearing TB1 and the bearing TB2 of the corrected tool axis TA. A stator 15 constituting the corrected tool axis driving device TM is disposed on the outer peripheral surface side of the rotor 14. In detail, the outer peripheral surface of the stator 15 is fixed to the inner peripheral surface of the second housing 13 so that a predetermined gap is formed between the inner peripheral surface of the stator 15 and the outer peripheral surface of the rotor 14. As a result, the corrected tool axis TA is rotationally driven together with the corrected tool T by driving the corrected tool axis driving device TM controlled by the control device CR.

[0024] (3. Grindstone correction operation) Next, the grinding wheel dressing operation will be described. As described in the problem to be solved by the invention, when the inventors of the present application dressed the grinding wheel G by varying the relative rotation speed between the dressing tool T and the grinding wheel G, there were still cases where chatter patterns occurred on the outer peripheral surface of the grinding wheel G. It was found that the cause of this was that when the natural frequency of the dressing tool T in the direction of the rotation axis TL becomes an integer multiple of the rotation frequency (rotation speed) of the grinding wheel G, resonance occurs, and this integer peak occurs on the outer peripheral surface of the grinding wheel G, resulting in chatter patterns.

[0025] In order to suppress the occurrence of chatter shapes on the outer peripheral surface of the grinding wheel G, the rotation frequency of the grinding wheel G should be set so that the natural frequency of the dressing tool T is not an integer multiple of the rotation frequency of the grinding wheel G. However, the dressing tool shaft TA of the dressing tool T is supported by a bearing TB1, and the natural frequency of the dressing tool T changes due to wear of the rolling elements, inner ring, outer ring, etc., deterioration of the lubricating oil, etc. If this change occurs, there is a risk that the set rotation frequency of the grinding wheel G will not be able to suppress the occurrence of chatter shapes on the outer peripheral surface of the grinding wheel G.

[0026] Therefore, first, the correction tool T is moved in the direction of the rotation axis of the grinding wheel G while varying the rotation frequency of the grinding wheel G, thereby roughly correcting the outer peripheral surface of the grinding wheel G with the correction tool T. The rotation frequency of the grinding wheel G at this time is varied so that the number of peaks that form chatter patterns is not constant, but is shifted by, for example, one peak. Then, one cycle when the rotation frequency of the grinding wheel G is varied is made different from one cycle of rough correction performed on the outer peripheral surface of the grinding wheel G with the correction tool T.

[0027] Specifically, the rotation frequency V of the grinding wheel G is expressed as the quotient obtained by dividing the natural frequency of the correction tool T by the number of peaks that form the chatter shape. Therefore, as shown in Fig. 3, the rotation frequency (first grinding wheel rotation frequency) V1 of the grinding wheel G at which the number of peaks is n (integer) (in this example, this is the rotation frequency when grinding the workpiece W with the grinding wheel G) and the rotation frequency (second grinding wheel rotation frequency) V2 of the grinding wheel G at which the number of peaks is n (integer)-1 are obtained.

[0028] Then, the rotation frequency V of the grinding wheel G is changed between the first grinding wheel rotation frequency V1 and the second grinding wheel rotation frequency V2 of the grinding wheel G. In FIG. 3, the frequency is changed linearly from the first grinding wheel rotation frequency V1 to the second grinding wheel rotation frequency V2, and then from the second grinding wheel rotation frequency V2 to the first grinding wheel rotation frequency V1. This causes the number of peaks that form chatter patterns to not be constant, but to be shifted. In particular, the more the frequency of change, the more effective it is.

[0029] 4A-4D, one cycle (one pass) of rough correction performed on the peripheral surface of the grinding wheel G by the correction tool T refers to the time (tp in FIG. 3) from when the grinding wheel G and the correction tool T are positioned at the correction start position (state in FIG. 4A), the peripheral surface of the grinding wheel G is corrected by the correction tool T (state in FIG. 4B), and then the grinding wheel G and the correction tool T are positioned at the correction start position again (states in FIG. 4C and FIG. 4D). Also, one cycle when the rotation frequency of the grinding wheel G is changed refers to the time (tv in FIG. 3) from when the grinding wheel G reaches the second grinding wheel rotation frequency V2 from the first grinding wheel rotation frequency V1 to when the grinding wheel G returns from the second grinding wheel rotation frequency V2 to the first grinding wheel rotation frequency V1.

[0030] If one cycle (tv) when the rotation frequency of the grinding wheel G is changed is synchronized with one cycle (one pass tp) of rough correction performed on the peripheral surface of the grinding wheel G by the correction tool T, chatter shapes are likely to occur, but if the cycle (tv, tp) is made different, the occurrence of chatter shapes can be further suppressed. Note that the repeated cycle of rough correction is 14 passes in this example.

[0031] Next, while keeping the rotational frequency of the grinding wheel G constant, the correction tool T is moved in the direction of the rotational axis of the grinding wheel G to perform fine correction of the peripheral surface of the grinding wheel G with the correction tool T. The reason for performing this fine correction is as follows. In the rough correction, the rotational frequency of the grinding wheel G is varied, but at this time, due to imbalance of the grinding wheel G, the center of rotation of the grinding wheel G may change, causing chatter patterns to appear on the peripheral surface of the grinding wheel G. Therefore, fine correction is performed at the rotational frequency when the workpiece W is actually ground with the grinding wheel G to remove the chatter patterns.

[0032] Specifically, as shown in Fig. 3, the rotational frequency V of the grinding wheel G in the fine dressing is maintained at a constant speed, which is the rotational frequency when the grinding wheel G grinds the workpiece W, i.e., the first grinding wheel rotational frequency V1 in this example. This makes it possible to remove almost all of the peaks remaining in the rough dressing, thereby suppressing the occurrence of chatter marks. However, since the number of peaks that become chatter marks at the first grinding wheel rotational frequency V1 is n (an integer), if fine dressing is performed for a long period of time, chatter marks will occur on the circumferential surface of the grinding wheel G. Therefore, the repeated cycle of fine dressing (two passes in this example) is performed until the outer circumferential surface of the grinding wheel G reaches the state required for grinding the workpiece W with the grinding wheel G that has been determined in advance.

[0033] (4. Control process of the grinding wheel dressing device 10 in the grinding device 1) Next, the control process (grinding wheel dressing method) of the grinding wheel dressing device 10 in the grinding apparatus 1 will be described with reference to the flowcharts of Figures 5A and 5B. The control device CR of the grinding wheel dressing device 10 sets the first grinding wheel rotation frequency V1 and the second grinding wheel rotation frequency V2 of the grinding wheel G (step S1 in Figure 5A).

[0034] Specifically, when the quotient obtained by dividing the natural frequency of the modified tool axis TA of the modified tool T by the rotation frequency when the workpiece W is ground with the grinding wheel G is an integer, the control device CR sets the rotation frequency when the workpiece W is ground with the grinding wheel G as the first grinding wheel rotation frequency V1. Then, the control device CR obtains the rotation frequency of the grinding wheel G when the natural frequency of the modified tool axis TA of the modified tool T is divided by an integer smaller than the above quotient, and sets the obtained rotation frequency of the grinding wheel G as the second grinding wheel rotation frequency V2.

[0035] The control device CR drives the grinding wheel spindle drive device GM and the correction tool spindle drive device TM to start rotating the grinding wheel G and the correction tool T (step S2 in FIG. 5A). Then, the grinding wheel G is periodically changed between the first grinding wheel rotation frequency V1 and the second grinding wheel rotation frequency V2 (step S3 in FIG. 5A).

[0036] Specifically, the control device CR sets one period when the rotation frequency of the grinding wheel G is varied by a time constant so as not to be synchronized with one period of rough correction performed on the outer peripheral surface of the grinding wheel G by the correction tool T. In other words, the time for one pass of rough correction is set to be different from the time it takes to linearly change from the first grinding wheel rotation frequency V1 to the second grinding wheel rotation frequency V2 and then linearly return from the second grinding wheel rotation frequency V2 to the first grinding wheel rotation frequency V1. Then, the rotation frequency of the grinding wheel G is periodically varied with the set time constant.

[0037] The control device CR drives the X-axis drive unit 4 to move the grinding wheel head 3 in the X-axis direction, and drives the Z-axis drive unit 9 to move the grinding wheel dressing device 10 together with the work table 5 in the Z-axis direction, and positions the grinding wheel G and the dressing tool T at the dressing start position (step S4 in FIG. 5A, rough dressing process). Then, for example, when the rotation frequency of the grinding wheel G becomes the first grinding wheel rotation frequency V1, the rough dressing is started at the same time (step S5 in FIG. 5A, rough dressing process). Then, the rough dressing is repeated until the predetermined number of passes set in advance is completed (step S6 in FIG. 5A, rough dressing process), and when the predetermined number of passes is completed, the rotation frequency of the grinding wheel G is returned to the first grinding wheel rotation frequency V1, and the grinding wheel G and the dressing tool T are moved to the dressing start position (step S7 in FIG. 5A, fine dressing process).

[0038] The control device CR sets the rotation frequency of the grinding wheel G to be maintained at the first grinding wheel rotation frequency V1 (step S8 in FIG. 5B, fine dressing process). Then, the grinding wheel G and the dressing tool T are positioned at the dressing start position, and at the same time, fine dressing is started (step S9 in FIG. 5B, fine dressing process), and fine dressing is repeated until a preset number of passes are completed (step S10 in FIG. 5B, fine dressing process). Then, when the predetermined number of passes are completed, the grinding wheel G is moved to a retreat position (step S11 in FIG. 5B), and the grinding wheel G and the dressing tool T are stopped from rotating (step S12 in FIG. 5B), and all processing is terminated.

[0039] (5. Other) In the above embodiment, the rotation frequency of the grinding wheel G in the rough correction is changed so that the number of peaks of the chatter shape is shifted by one peak. However, this is not limited to this, and the frequency may be changed so that the number of peaks is shifted by any number of peaks. Also, the rotation frequency of the grinding wheel G in one pass of the rough correction is changed linearly from the first grinding wheel rotation frequency V1 to the second grinding wheel rotation frequency V2, and from the second grinding wheel rotation frequency V2 to the first grinding wheel rotation frequency V1. However, this is not limited to this, and the frequency may be changed in a zigzag manner or in a curved manner, for example.

[0040] In addition, although the case where multiple passes are performed in the rough correction has been described, the rough correction may be completed in one pass. Also, although the case where one cycle when the rotation frequency of the grinding wheel G is changed is not synchronized with one cycle of the rough correction performed on the peripheral surface of the grinding wheel G by the correction tool T has been described, they may be synchronized if it is possible to remove the chatter shape in the fine correction.

[0041] Although a vertical grinding wheel dressing device has been described as an example of the grinding wheel dressing device 10, a horizontal grinding wheel dressing device can be applied in the same way. Furthermore, a cylindrical grinding device has been described as an example of the grinding device 1 to which the grinding wheel dressing device 10 is applied, but an internal grinding device, a centerless grinding device, and a surface grinding device can be applied in the same way. [Explanation of symbols]

[0042] 1; grinding processing device, 3; grinding wheel head, 10; grinding wheel dressing device, G; grinding wheel, GA; grinding wheel spindle, GM; grinding wheel spindle drive device, T; dressing tool, TA; dressing tool spindle, TM; dressing tool spindle drive device, CR; control device, TB1,TB2; bearings

Claims

1. a correction tool that is supported so as to be rotatably driven and moves relative to the grinding wheel in a direction of a rotation axis of the grinding wheel that is rotated, thereby correcting a peripheral surface of the grinding wheel; a control device for controlling a rotation frequency of the grinding wheel and for controlling a relative movement of the dressing tool and the grinding wheel; A grinding wheel dressing device comprising: The control device performs coarse correction of the peripheral surface of the grinding wheel with the correction tool by relatively moving the correction tool and the grinding wheel while varying the rotational frequency of the grinding wheel, and performs fine correction of the peripheral surface of the grinding wheel with the correction tool by relatively moving the correction tool and the grinding wheel while keeping the rotational frequency of the grinding wheel constant.

2. 2. The grinding wheel dressing device according to claim 1, wherein, when a quotient obtained by dividing the natural frequency of the dressing tool shaft of the dressing tool by a rotational frequency (referred to as a first grinding wheel rotational frequency) when the workpiece is ground with the grinding wheel is an integer, the control device divides the natural frequency by an integer smaller than the quotient to obtain a rotational frequency of the grinding wheel (referred to as a second grinding wheel rotational frequency), and performs the rough dressing while varying the rotational frequency of the grinding wheel between the first grinding wheel rotational frequency and the second grinding wheel rotational frequency.

3. The grinding wheel dressing device according to claim 2 , wherein the control device performs the fine dressing while maintaining the first grinding wheel rotation frequency.

4. the control device performs the rough correction by controlling so that one cycle tp of the rough correction performed on the peripheral surface of the grinding wheel by the correction tool is different from one cycle tv when the rotation frequency of the grinding wheel is changed; The one cycle tp is a time from when the grinding wheel and the correction tool are positioned at the correction start position, when the outer peripheral surface of the grinding wheel is corrected by the correction tool, and then when the grinding wheel and the correction tool are again positioned at the correction start position, 4. The grinding wheel dressing device according to claim 2, wherein one period t v is a time taken for the grinding wheel to reach the second grinding wheel rotation frequency from the first grinding wheel rotation frequency and return from the second grinding wheel rotation frequency to the first grinding wheel rotation frequency.

5. 5. A grinding wheel dressing device according to claim 1, wherein a dressing tool shaft of the dressing tool is rotatably supported by a rolling bearing.

6. A grinding wheel dressing method for dressing a peripheral surface of a grinding wheel that is rotated by a dressing tool that is rotated, comprising the steps of: a rough dressing process in which the dressing tool and the grinding wheel are moved relative to each other while varying the rotation frequency of the grinding wheel, thereby roughly dressing the peripheral surface of the grinding wheel with the dressing tool; a precision dressing step in which the dressing tool and the grinding wheel are moved relative to each other while maintaining a constant rotational frequency of the grinding wheel, thereby performing precision dressing of the peripheral surface of the grinding wheel with the dressing tool; A method for adjusting a grinding wheel comprising:

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