JP2004082300A - Dressing method of grinding wheel in centerless grinder and dressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dressing method in a centerless grinder which enables reduction of dressing time and stabilization of grinding accuracy after dressing and accurate determination of whether a dressing state is good or not. <P>SOLUTION: This dressing method includes a process S2 of rotating a grinding wheel at almost the same speed as that in grinding, a dressing process S4 of rotating a rotary dresser at almost the same peripheral speed as that of the grinding wheel or a slightly faster or slower peripheral speed than it and enabling the rotary dresser to feed the grinding wheel by a specified amount each time when it traverses a whole width of the grinding wheel with the predetermined number of times, and a determination process S6 of determining the dressing state of the grinding wheel by variation of current values and power values of a driving motor of the rotary dresser in the dressing process S4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dressing method and a dressing device for a grinding wheel in a centerless grinding machine for dressing a grinding wheel such as a grinding wheel and an adjusting grinding wheel in a centerless grinding machine.
[0002]
[Prior art]
Conventionally, when dressing (shaping and sharpening) a high-hardness grinding wheel (generally a super-abrasive wheel including a diamond wheel) represented by a CBN wheel in a centerless grinder, a rotary diamond is mainly used as a rotary dresser. A method in which the rotary dresser is cut into the grinding wheel by a predetermined amount each time the entire width of the grinding wheel is traversed once while rotating the rotary dresser in the down-cut direction or the up-cut direction with respect to the grinding wheel. Has been adopted.
[0003]
In this case, since the diameter of the rotary dresser is smaller than the diameter of the grinding wheel, it is necessary to prevent the wear of the diamond abrasive grains of the rotary dresser. And the rotation speed is adjusted to the peripheral speed of the rotary dresser.
[0004]
Also, as a method for determining the quality of a dressing state of a grinding wheel, conventionally, (1) a method of directly measuring a shape of a grinding wheel after dressing, and (2) a method described in Japanese Patent No. 3165488, AE sensor detects vibrations caused by contact between the grinding wheel and the rotary dresser, and determines the in-process by analyzing the data. (3) Measures the shape of the grinding wheel by post-process using ultrasonic waves. There is a determination method and the like.
[0005]
[Problems to be solved by the invention]
When dressing a grinding wheel using a superabrasive grindstone with a rotary dresser such as a rotary diamond, there is a drawback that conventionally a very long dressing time is required. If the dressing of the grinding wheel is performed with the rotation speed during grinding, the diameter of the rotary dresser is smaller than the diameter of the grinding wheel. It is not possible to dress with high precision, for example, the diamond abrasive grains wear during traverse and the straightness of the grinding wheel deteriorates. For this reason, conventionally, deceleration control for adjusting the peripheral speed of the grinding wheel to the peripheral speed of the rotary dresser is performed, and the grinding wheel is dressed in this state. Therefore, when the dress lead (the amount by which the rotary dresser traverses per revolution of the grinding wheel) is fixed, it is necessary to reduce the traverse speed of the rotary dresser, and it takes a long time to dress.
[0006]
In addition, in the conventional dressing method, since the rotation speed of the grinding wheel changes greatly between grinding and dressing, when the grinding wheel returns to the grinding rotation speed after dressing, the phase and amount of imbalance change. , The dynamic runout increases. In particular, in the case of a CBN grinding wheel, the difference is large because the number of rotations used is relatively high.
[0007]
Further, the conventional dress state determination method has the following problem. That is, in the above method (1), although a special device is not required for the determination of the dressing state, it is necessary to stop the grinding wheel and, for example, open the grinding wheel cover for the determination, and then to perform the measurement. If it is not good, the grinding wheel cover will be closed and the grinding wheel will be rotated and dressing will be performed again.Therefore, dressing and measurement must be repeated. You can only judge on a certain line.
[0008]
The above method (2) can reduce the labor and time required for the determination because the automatic determination can be performed in-process, but it requires a separate device, and also has a vibration and Since noise is also picked up, the reliability decreases when other machines are operating in the vicinity. The above method (3) can measure even when the grinding wheel is rotating, but it requires time to incorporate the measurement cycle into the dress cycle, and requires another device such as an ultrasonic device. .
[0009]
The present invention has been made in view of the conventional problems, and provides a dressing method and a dressing apparatus for a centerless grinding machine capable of shortening a dressing time, stabilizing grinding accuracy after dressing, and accurately determining whether a dress state is good. The purpose is to:
[0010]
[Means for Solving the Problems]
The dressing method of the present invention is a step of rotating the grinding wheel at substantially the same speed as during grinding, and rotating the rotary dresser at a peripheral speed substantially equal to the grinding wheel, a slightly faster peripheral speed or a slightly slower peripheral speed, A dressing step of cutting the rotary dresser into the grinding wheel by a predetermined amount each time the entire width of the grinding wheel is traversed a predetermined number of times; and a change in a current value or a power value of a drive motor of the rotary dresser in the dressing step. And a determination step of determining the dress state of
[0011]
The dressing method of the present invention detects a change in the rotation speed of the rotary dresser due to a dress resistance, and controls the current of the drive motor so as to correct the delay or advance of the rotation speed of the rotary dresser. It is desirable to include a step. The dressing method of the present invention preferably includes the determination step of determining that the dress state is good when the current value or the power value of the drive motor is substantially constant.
[0012]
The dressing method of the present invention further includes a threshold based on a current value or a power value of the drive motor when the rotary dresser contacts substantially the entire surface of the grinding wheel, and a current value of the drive motor in the dressing process. Or comparing the power value with the power value, including the determination step of determining the dress state is good when the current value or the power value of the drive motor in the dressing step is equal to or more than a threshold value, when it is determined that the dressing state is good It is desirable to end the dressing step.
[0013]
The dressing device of the present invention is a grinding wheel drive motor that rotates a grinding wheel at a speed substantially equal to that at the time of grinding, and a rotary dresser that rotates at a peripheral speed substantially equal to the grinding wheel, a slightly faster peripheral speed or a slightly slower peripheral speed. A dresser driving motor, dress control means for controlling the rotary dresser to cut into the grinding wheel by a predetermined amount each time the entire width of the grinding wheel is traversed a predetermined number of times, and a current value of the dresser driving motor during dressing or The power value is compared with the current value of the dresser drive motor when the rotary dresser contacts substantially the entire surface of the grinding wheel or the threshold value based on the power value, and the current of the dresser drive motor at the time of dressing is compared. Determining means for ending the dressing when the value or the power value is equal to or more than the threshold value.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a dressing apparatus for a centerless grinding machine according to the present invention.
[0015]
As shown in FIG. 1, the dressing apparatus includes a rotary dresser 2 for dressing a grinding wheel 1, a grinding wheel drive motor 4 for driving the grinding wheel 1 to rotate around a spindle 3, and a grinding wheel drive motor 4. A pulse encoder 5 for detecting the rotation speed of the grinding wheel, a grinding wheel rotation control means 6 for controlling the rotation speed of the grinding wheel drive motor 4, and a dresser drive motor for rotating the rotary dresser 2 around a dresser shaft 8 on the dress head 7. 9, a pulse encoder 10 for detecting the rotation speed of the dresser drive motor 9, a dresser rotation control means 11 for controlling the rotation speed of the dresser drive motor 9, and a notch for cutting and driving the rotary dresser 2 toward the grinding wheel 1. Traverse means 13 for traversing the rotary dresser 2 in the width direction of the grinding wheel 1; A dress control unit 14 for controlling the stage 12 and the traverse unit 13 controls the grinding wheel 1 by the rotary dresser 2 dresses, and a judging means 15 judges the quality of dress condition of the grinding wheel 1.
[0016]
The grinding wheel 1 is formed by consolidating abrasive grains with a binder and forming the outer shape into a substantially cylindrical shape. For example, a high-hardness grinding wheel such as a CBN grinding wheel and other super-abrasive grinding wheels are used. . The grinding wheel drive motor 4 is constituted by an AC servomotor with a pulse encoder 5, and drives the grinding wheel 1 at substantially the same rotation speed when grinding and dressing a workpiece. Therefore, the rotation speed of the grinding wheel 1 during dressing is substantially equal to the rotation speed during grinding. Incidentally, when the grinding wheel 1 is a CBN grinding wheel, the maximum peripheral speed used is 3600 m / min. Is common.
[0017]
The pulse encoder 5 constitutes a speed detecting means for detecting a rotation speed of the grinding wheel 1, and outputs a speed signal corresponding to a change in the rotation speed of the grinding wheel drive motor 4 when the rotation speed of the grinding wheel drive motor 4 changes. When the rotation speed of the grinding wheel 1 changes (lags or advances) due to a change in grinding resistance during grinding, a change in dress resistance during dressing, or the like, the grinding wheel rotation control means 6 outputs a speed signal from the pulse encoder 5. Based on this, a control current is added to the grinding wheel drive motor 4 in a direction to correct the delay or advance, and feedback control is performed so that the grinding wheel 1 rotates at a substantially constant speed. The grinding wheel rotation control means 6 controls the rotation speed of the grinding wheel drive motor 4 so that the grinding wheel 1 rotates at substantially the same speed as during grinding even during dressing.
[0018]
The rotary dresser 2 is for dressing the outer peripheral surface of the grinding wheel 1. The dresser 7 is movable on the grinding wheel 1 in the cutting direction and the traverse direction, and is substantially the same as the spindle 3 of the grinding wheel 1. It is mounted via a parallel dresser shaft 8 and rotates the dresser drive motor 9 in a predetermined direction (downcut direction or upcut direction) while rotating the entire width of the outer peripheral surface of the grinding wheel 1 a predetermined number of times (for example, 1). Each time the traverse is performed, the dressing operation of cutting the grinding wheel 1 by a predetermined amount is repeated to dress the outer peripheral surface.
[0019]
In addition, as the rotary dresser 2, for example, a rotary diamond having diamond abrasive grains fixed on the outer periphery is used, but a rotary diamond other than the rotary diamond may be used. The dresser shaft 8 of the rotary dresser 2 does not necessarily have to be parallel to the spindle 3. The dress head 7 is movable in the cutting direction by driving the cutting means 12 and in the traverse direction by driving the traverse means 13.
[0020]
The dresser drive motor 9 is constituted by, for example, an AC servomotor with a pulse encoder 10, and rotates the rotary dresser 2 at a peripheral speed substantially equal to the grinding wheel 1, a slightly faster peripheral speed or a slightly slower peripheral speed, in a downcut direction or an upcut. It is driven to rotate in the direction. The dresser driving motor 9 is provided on the dress head 7 together with the rotary dresser 2. The pulse encoder 10 constitutes a speed detecting means for detecting the rotation speed of the rotary dresser 2, and outputs a speed signal corresponding to the change of the rotation speed of the dresser drive motor 9 when the rotation speed changes.
[0021]
The dresser rotation control means 11 is for controlling the dresser drive motor 9 so as to rotate the rotary dresser 2 at a peripheral speed substantially equal to the grinding wheel 1, at a slightly higher peripheral speed, or at a slightly lower peripheral speed. When there is a rotation command from the means 14, the dresser drive motor 9 is controlled so that the rotary dresser 2 rotates at a predetermined speed, and the rotation speed of the rotary dresser 2 changes (delay or delay) due to a change in dress resistance during dressing. In this case, the control signal I is added to the dresser drive motor 9 in a direction to correct the delay or the advance, based on the speed signal from the pulse encoder 10, and the rotary dresser 2 rotates at a substantially constant speed. Feedback control.
[0022]
The dressing method of the grinding wheel 1 includes a down-cut method of rotating the rotary dresser 2 in the forward direction (the direction of the arrow b) with respect to the grinding wheel 1 rotating in the direction of the arrow a in FIG. There is an up-cut method in which the dresser 2 is rotated in the opposite direction (the direction indicated by the arrow c). At the time of dressing by the down-cut method, the peripheral speed is substantially equal to or slightly lower than that of the grinding wheel 1, and is increased. During dressing by the cutting method, the rotary dresser 2 may be rotated at a peripheral speed substantially equal to or higher than that of the grinding wheel 1. In such a case, the dresser rotation control means 11 controls the dresser drive motor 9 so that the rotary dresser 2 rotates at that speed.
[0023]
The dress control means 14 issues a rotation command to the dresser rotation control means 11 when dressing the grinding wheel 1, and issues a dress command based on a predetermined control program or the like when the rotary dresser 2 reaches a predetermined rotation speed. Then, the cutting means 12 and the traverse means 13 are controlled so that the rotary dresser 2 cuts the grinding wheel 1 by a predetermined amount every time the rotary dresser 2 traverses the entire width of the grinding wheel 1 a predetermined number of times, for example, once. The dressing operation of the grinding wheel 1 is controlled. Further, the dress control means 14 continues the dressing after the start of the dressing while the judging means 15 judges that the dress state of the grinding wheel 1 is defective, and the dressing means 15 judges that the dress state of the grinding wheel 1 is good. Then, the dress is ended after the end of the traverse.
[0024]
The judging means 15 detects a change in the current value of the control current I of the dresser drive motor 9 during the actual dressing time T when the rotary dresser 2 traverses the entire width of the grinding wheel 1, and judges the quality of the dress state based on the change. The dress state is determined to be good when the current value of the control current I of the dresser drive motor 9 during the actual dressing time T during dressing is substantially equal to or greater than the threshold value TH with reference to the threshold value TH.
[0025]
That is, when the rotary dresser 2 traverses the grinding wheel 1 in the width direction as shown in FIGS. 4 (A) and 4 (B), the determination means 15 determines when the contact of the rotary dresser 2 with the grinding wheel 1 starts. During the actual dressing time T from T1 to the contact end time T2, the current value of the control current I of the dresser driving motor 9 is compared with the threshold value TH in real time, and the current value of the control current I during the actual dressing time T is always The dress state is determined to be good when it is substantially constant at or above the threshold value TH, and if the current value of the control current I during the actual dressing time T is temporarily less than the threshold value TH, it is determined that the dress is defective.
[0026]
The contact start time T1 can be detected by the rise of the control current I of the dresser drive motor 9, and the contact end time T2 can be detected by the fall of the control current I. The actual dress time T is from the rise to the fall. The contact start time T1 and the contact end time T2 can be detected by other methods, such as by detecting the position of the rotary dresser 2 in the traverse direction.
[0027]
The threshold value TH is set based on the current value of the control current I of the dresser drive motor 9 when the rotary dresser 2 comes into contact with substantially the entire surface of the grinding wheel 1, taking a predetermined fluctuation range into consideration. Note that the threshold value TH may be set at the lower limit value of the fluctuation range of the control current I, or may be set at both the upper limit value and the lower limit value so that the current value of the control current I is between the upper limit value and the lower limit value. In some cases, the dress state may be determined to be good. The control current I of the dresser drive motor 9 may detect the current actually flowing through the dresser drive motor 9 or may detect the current added to the dresser drive motor 9 from the dresser rotation control means 11.
[0028]
Next, a dressing method using the dressing device having the above configuration will be described. For example, when dressing the grinding wheel 1 with the rotary dresser 2 rotating in the down-cut direction between the end of the previous grinding step S1 and the start of the next grinding step S7, as shown in FIG. The process is performed through steps S2 to S6 such as a vehicle rotation control step S2, a dresser rotation step S3, a dressing step S4, a dresser rotation control step S5, and a determination step S6.
[0029]
That is, when the previous grinding step S1 is completed, a grinding wheel rotation control step S2 for rotating the grinding wheel 1 at a rotational speed substantially equal to that at the time of grinding is executed. In the grinding wheel rotation control step S2, the grinding wheel rotation control means 6 controls the grinding wheel drive motor 4 to rotate the grinding wheel 1 after the grinding at a speed substantially equal to that in the grinding direction in the direction indicated by the arrow a in FIG. Rotate to.
[0030]
Since there is no grinding load due to the workpiece unlike during grinding, if the rotation speed of the grinding wheel 1 increases, the pulse encoder 4 detects the change, and the grinding wheel rotation control means 6 controls the grinding wheel drive motor 4. By reducing the current, the rotation speed of the grinding wheel 1 is controlled to a constant speed substantially equal to that during grinding.
[0031]
The grinding wheel rotation control step S2 continues until the end of the dressing step S4. If the rotation speed of the grinding wheel 1 changes due to a change in dress resistance during the dressing, the pulse encoder 5 detects the change in the rotation speed and the grinding wheel. The wheel rotation control means 6 performs feedback control for adding a control current to the grinding wheel drive motor 4 in a direction to correct the delay or advance of the rotation speed. Therefore, the grinding wheel 1 rotates at a substantially constant speed until the end of the dressing step S4.
[0032]
When the dressing is performed by rotating the stopped grinding wheel 1, as shown by a two-dot chain line in FIG. 1, a rotation command or the like is issued from the dress control unit 14 to the grinding wheel rotation control unit 6. What is necessary is just to rotate the grinding wheel 1 at a peripheral speed substantially equal to that at the time of grinding.
[0033]
Thus, the dressing time can be reduced by performing dressing while rotating the grinding wheel 1 at a speed substantially equal to the rotation speed at the time of grinding. That is, if the dressing of the rotary dresser 2 is made constant when dressing the grinding wheel 1, the traverse speed of the rotary dresser 2 can be increased as the rotation speed of the grinding wheel 1 increases, so that the grinding wheel 1 is rotated at substantially the same speed as during grinding, and dressing the grinding wheel 1 with the rotary dresser 2 in that state allows the dressing time to be reduced despite the fact that the grinding wheel 1 is a super-abrasive wheel. Can be shortened.
[0034]
In addition, since the rotational speeds of the dressing and the grinding are substantially the same, the next grinding step S7 can be executed after the dressing is completed, and in this case, the unbalance phase and the like do not change during the grinding. The object can be ground with high precision. In addition, since the rotational speeds during dressing and during grinding are substantially equal, the amount of heat generated from the spindle bearing that rotatably supports the spindle 3 of the grinding wheel 1 does not fluctuate and is thermally stable.
[0035]
As described above, while the rotation speed of the grinding wheel 1 is kept substantially equal to that at the time of grinding, a rotation command is issued from the dress control means 14 at a predetermined time, and the rotary dresser 2 is rotated at a peripheral speed substantially equal to or slightly lower than that of the grinding wheel 1. A dresser rotation step S3 for rotating the peripheral gear in the downcut direction (the direction indicated by the arrow b in FIG. 3) at the peripheral speed is executed. In the dresser rotation step S3, the dresser rotation control means 11 controls the dresser drive motor 9 in response to a rotation command from the dress control means 14, and the drive of the dresser drive motor 9 causes the rotary dresser 2 to be substantially the same as the grinding wheel 1. Rotate in the downcut direction at the same peripheral speed or slightly lower peripheral speed. Incidentally, the peripheral speed ratio between the rotary dresser 2 and the grinding wheel 1 is suitably in the range of about 0.85 to 1, and the speed is appropriately set according to the diameter, material, etc. of the grinding wheel 1 and the rotary dresser 2. I do.
[0036]
When the grinding wheel 1 rotates at a rotational speed substantially equal to that at the time of grinding, and the rotary dresser 2 rotates at a peripheral speed substantially equal to or slightly lower than that of the grinding wheel 1, the dress control means 14 operates based on a predetermined program. A cutting command is issued and the cutting means 12 and the traversing means 13 are operated, so that the rotary dresser 2 traverses the entire width of the grinding wheel 1 once as shown in FIG. The dressing step S4 is performed to cut the grinding wheel 1 by a predetermined amount, and the shape (runout, roundness, straightness) of the grinding wheel 1 is corrected until the dressing resistance of the rotary dresser 2 becomes substantially uniform.
[0037]
When the rotary dresser 2 traverses the entire width of the grinding wheel 1 with a predetermined cutting amount, if the straightness and roundness of the grinding wheel 1 are poor, the dress resistance of the grinding wheel 1 to the rotary dresser 2 changes. For example, as shown in FIG. 4 (A), when the straightness of the grinding wheel 1 is poor, the contact ratio of the rotary dresser 2 per rotation of the grinding wheel 1 varies depending on the size of the diameter, and a portion having a large diameter. In this case, the dress resistance increases, and in small portions, the resistance decreases. This is the same when the roundness of the grinding wheel 1 is poor due to the presence of the concave portion 1a on the outer peripheral surface as shown in FIG. 5, and the dress resistance is large between the good roundness portion and the bad roundness portion. Change.
[0038]
If the dress resistance changes during the dressing step S4, the rotational speed of the rotary dresser 2 changes (lags or advances), so that the pulse encoder 10 detects the change in speed and the dresser rotation control means 11 causes the rotary dresser 2 to rotate. A dresser rotation control step S5 for controlling the control current I of the dresser drive motor 9 is performed so as to correct the delay or advance of the rotation speed. Therefore, the rotary dresser 2 rotates at a substantially constant speed until the end of the dressing step S4.
[0039]
When the rotary dresser 2 starts dressing the grinding wheel 1, the determination means 15 determines the dress state of the grinding wheel 1 based on a change in the control current I of the dresser drive motor 9 during the actual dressing time T. The determination step S6 is performed. That is, there is a correlation between the dress resistance of the rotary dresser 2 and the control current I of the dresser drive motor 9, and the control current I of the dresser drive motor 9 changes with the change of the dress resistance. By comparing the control current I of the dresser drive motor 9 during the actual dressing time T with the threshold value TH in real time, the quality of the dressing state of the grinding wheel 1 can be accurately and quickly determined.
[0040]
If the determination means 15 determines that the dress state is good, the dress control means 14 issues a dress end command based on the determination result, and moves the rotary dresser 2 through the cutting means 12 and the traverse means 13 to a standby position or the like. At the same time, the rotation of the rotary dresser 2 is stopped via the dresser rotation control means 11, and the dressing step S4 is completed with the end of the traverse. If the determining means 15 determines that the dressing is defective, the dressing step S4 of cutting the rotary dresser 2 into the grinding wheel 1 by a predetermined amount each time the rotary dresser 2 traverses the entire width of the grinding wheel 1 once is continued, The outer peripheral surface of the grinding wheel 1 is sequentially dressed.
[0041]
The determination means 15 stores the change in the current value of the control current I of the dresser drive motor 9 during the actual dressing time T in the storage means, and stores the stored data after the contact of the rotary dresser 2 with the grinding wheel 1 is completed. The quality of the dress state may be determined by comparing with a threshold value. In this case, the quality of the dress situation is determined for each traverse.
[0042]
When the straightness of the grinding wheel 1 is poor, as shown in FIG. 4 (A), the contact ratio of the rotary dresser 2 to the grinding wheel 1 is high and the dress resistance is large in the portion having a large diameter. The control current I of the dresser drive motor 9 at T becomes very large as compared with the case of no load, and becomes small in a portion having a small diameter.
[0043]
However, as a result of the dressing, as shown in FIG. 4B, if the straightness of the grinding wheel 1 is improved, dress resistance is applied to the rotary dresser 2 almost uniformly over the entire width of the grinding wheel 1. The current value of the control current I of the dresser drive motor 9 during the actual dressing time T changes with a small fluctuation width equal to or larger than the threshold value TH.
[0044]
Accordingly, the determination means 15 determines whether or not the current value of the control current I of the dresser drive motor 9 at the actual dressing time T is equal to or greater than the threshold value TH based on the threshold value TH. The state, for example, roundness, runout, and straightness can be automatically grasped in process.
[0045]
Dressing the grinding wheel 1 rotating at a speed substantially equal to the rotation speed at the time of grinding with the rotary dresser 2 rotating in the downcut direction at a peripheral speed substantially equal to or slightly lower than the peripheral speed thereof. Accordingly, the shape (run-out, roundness, straightness) of the grinding wheel 1 can be corrected in a short time by the crushing action of the rotary dresser 2 on the abrasive grains of the grinding wheel 1. In addition, since the rotary dresser 2 rotates at a peripheral speed substantially equal to or slightly lower than the peripheral speed of the grinding wheel 1 rotating at a speed substantially equal to that during grinding, wear of the diamond abrasive grains of the rotary dresser 2 due to slippage. And the grinding wheel 1 can be dressed with high precision.
[0046]
By grasping the change in the current value of the control current I of the dresser drive motor 9 during the actual dressing time T, the dress resistance by the grinding wheel 1 can be grasped in process, and the change in the current value of the control current I is determined by the determination means 15. By determining the dress state by comparing with the threshold value TH in real time, the completion of the dress can be automatically and easily and reliably determined in-process.
[0047]
Moreover, since the quality of the dressing state is determined based on the change in the current value of the control current I of the dresser drive motor 9 during the actual dressing time T, other equipment is not required and the determination is direct and the determination accuracy is high. Also, automation of dress control can be easily promoted. Further, if the dress resistance is uniform, it means that the entire surface of the grinding wheel 1 is in contact with the trajectory of the rotary dresser 2, so that the straightness of the grinding wheel 1 can be determined. Also, while the grinding wheel 1 rotates at a speed substantially equal to that at the time of grinding, the rotary dresser 2 rotates at a circumferential speed substantially equal to or slightly lower than that of the grinding wheel 1, so that the dress lead is rotated. It becomes sufficiently smaller than the dresser width of the dresser 2, and the runout and roundness of the grinding wheel 1 can also be determined.
[0048]
Further, by detecting a change in the control current I of the dresser drive motor 9 during the actual dressing time T, the contact of the rotary dresser 2 with the grinding wheel 1 can be detected, and the bearing side of the rotary dresser 2 can be detected. It is also possible to diagnose abnormalities.
[0049]
Although the embodiments of the present invention have been described in detail, the present invention is not limited to the embodiments, and various changes can be made without departing from the gist. For example, in the embodiment, the dressing by the down-cut method is described in detail. However, the present invention can be similarly performed when the grinding wheel 1 is dressed by the up-cut method. In the case of the down-cut method, in order to reduce the wear of the diamond abrasive grains, the rotary dresser 2 may be rotated at a peripheral speed equal to or slightly higher than the rotational speed of the grinding wheel 1. desirable.
[0050]
Further, in the embodiment, the quality of the dressing state of the grinding wheel 1 is automatically determined by the determination means 15, but the current waveform of the control current I of the dresser drive motor 9 during the actual dressing time T is determined in real time. A monitor to be displayed is provided at a predetermined position on the operation panel or the like. An operator looks at the current waveform of the control current I displayed on the monitor, and if the current waveform becomes substantially constant over the entire width of the grinding wheel 1, the dressing state is established. May be determined to be good, and the dressing process may be manually terminated. Also in this case, if the reference such as the threshold value TH is displayed on the monitor, it is possible to easily determine the quality of the dress state without requiring skill.
[0051]
Further, in the embodiment, an AC servomotor is used as the dresser drive motor 9, but another drive motor may be used as long as the rotation speed can be controlled by the control current I. The driving method of the rotary dresser 2 may be belt driving, high frequency spindle driving, or other coupling driving.
[0052]
When an AC servomotor is used for the drive motors 4, 9, the pulse encoders 5, 10 may be provided in the AC servomotor itself or may be provided outside. Further, the rotation control means 6, 11 for feedback controlling the AC servomotor may be provided on a control board of the AC servomotor itself.
[0053]
Further, the embodiment exemplifies a case in which the grinding wheel 1 using a super-abrasive grindstone typified by a CBN grindstone is to be dressed, but the grinding wheel 1 may be something other than a super-abrasive grindstone, The same applies to the case where the adjustment grinding wheel is to be dressed. Therefore, if the grinding wheel is a centerless grinding machine, the grinding wheel 1 and / or the adjusting grinding wheel can be dressed.
[0054]
At the time of dressing of the adjusting wheel, for example, mark the outer circumference at two or more places in the width direction such as both ends and the center with magic ink or other markers in advance, and if this disappears in the entire area, judge that it has touched the entire surface In this case as well, in this case, the dressing completion point can be determined by using the dress resistance as torque in the in-process, and the automation can be easily performed.
[0055]
In addition to the determination of the dress state based on the change in the current value of the control current I of the dresser drive motor 9, the change in the control power of the dresser drive motor 9, the change in the load current of the dresser drive motor 9, the load of the dresser drive motor 9 The dress state may be determined based on a change in the power value of the power.
[0056]
In the embodiment, the rotary dresser 2 is moved by the cutting means 12 and the traverse means 13, but the grinding wheel 1 and / or the rotary dresser 2 may be relatively moved in the cutting direction and the traverse direction. good.
[0057]
In the embodiment, the AC servo motor is used as the grinding wheel drive motor 4, but another motor can be used. In this case, the rotation speed of the grinding wheel 1 may slightly change due to the dress resistance, but there is no problem. When another motor is used, the grinding wheel rotation control means 6 can be omitted.
[0058]
The rotational speed of the rotary dresser 2 is set to a peripheral speed substantially equal to the rotational speed of the grinding wheel, a slightly higher peripheral speed, or a slightly lower peripheral speed, regardless of whether the rotational direction is the down-cut direction or the up-cut direction. By increasing the rotation speed of the rotary dresser 2, it is possible to reduce wear of diamond abrasive grains and the like.
[0059]
【The invention's effect】
The dressing method of the present invention includes a step of rotating the grinding wheel at a speed substantially equal to that at the time of grinding, and a method of rotating the rotary dresser at a peripheral speed substantially equal to that of the grinding wheel, a slightly faster peripheral speed or a slightly slower peripheral speed. A dressing step of cutting the rotary dresser into the grinding wheel by a predetermined amount each time the entire width of the car is traversed a predetermined number of times; and determining a dressing state of the grinding wheel based on a change in a current value or an electric power value of a drive motor of the rotary dresser in the dressing step. Since the determination step is performed, the dressing time can be reduced, the stability of the grinding wheel at the time of grinding after dressing can be improved, and the quality of the dressing state can be accurately determined.
[0060]
Further, the method includes a step of detecting a change in the rotation speed of the rotary dresser due to the dress resistance and controlling the current of the drive motor so as to correct the delay or advance of the rotation speed of the rotary dresser. Can stabilize the rotation speed.
[0061]
Further, since the method includes a determination step of determining that the dress state is good when the current value or the power value of the drive motor is substantially constant, the dress state can be accurately determined.
[0062]
Further, a threshold value based on the current value or power value of the drive motor when the rotary dresser contacts substantially the entire surface of the grinding wheel is compared with the current value or power value of the drive motor in the dressing process. The method includes a determination step of determining that the dress state is good when the current value or the power value of the drive motor is equal to or more than a threshold value, and terminates the dress step when it is determined that the dress state is good. The dress can be surely formed without any excess or shortage, and the dress can be automatically controlled easily.
[0063]
The dressing device of the present invention is a grinding wheel drive motor for rotating the grinding wheel at a speed substantially equal to that at the time of grinding, and a rotary dresser is rotated at a circumferential speed substantially equal to the grinding wheel, a slightly faster circumferential speed or a slightly slower circumferential speed. Dresser drive motor, dress control means for controlling the rotary dresser to cut into the grinding wheel by a predetermined amount each time the entire width of the grinding wheel is traversed a predetermined number of times, the current value or power value of the dresser drive motor at the time of dressing, When the current value or the power value of the dresser drive motor at the time of dressing is greater than or equal to the threshold value when compared with the threshold value based on the current value or the power value of the dresser drive motor when the rotary dresser contacts substantially the entire surface of the grinding wheel. Since it is provided with a determination means for ending the dressing, the dressing time can be reduced, and the grinding accuracy at the time of grinding after dressing is stable, and Can determine the quality of less state accurately, thus eliminating the useless dressing, also extend grinding wheel life.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control system showing an embodiment of the present invention.
FIG. 2 is a process chart showing one embodiment of the present invention.
FIG. 3 is an explanatory view of a grinding wheel and a rotation direction of a rotary dresser according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram of a dressing process and a determination process according to the embodiment of the present invention.
FIG. 5 is an explanatory diagram of the roundness of a grinding wheel showing one embodiment of the present invention.
FIG. 6 is an explanatory diagram of a traverse and a cut showing one embodiment of the present invention.
[Explanation of symbols]
1 grinding wheel
2 Rotary dresser
4 Wheel drive motor
6 Wheel wheel rotation control means
9 Dresser drive motor
11 Dresser rotation control means
14 Dress control means

Claims (5)

Rotating the grinding wheel at a speed substantially equal to that at the time of grinding; rotating the rotary dresser at a peripheral speed substantially equal to the grinding wheel, at a slightly higher peripheral speed or at a slightly lower peripheral speed to set the entire width of the grinding wheel to a predetermined value. A dressing step of cutting the rotary dresser into the grinding wheel by a predetermined amount each time the traverse is performed, and a determination of determining a dressing state of the grinding wheel based on a change in a current value or a power value of a drive motor of the rotary dresser in the dressing step. And a dressing method for a grinding wheel in a centerless grinding machine. Detecting a change in the rotational speed of the rotary dresser due to a dress resistance, and controlling a current of the drive motor so as to correct the delay or advance of the rotational speed of the rotary dresser. The method for dressing a grinding wheel in a centerless grinding machine according to claim 1. The dressing method for a grinding wheel in a centerless grinding machine according to claim 1 or 2, further comprising the determining step of determining that the dress state is good when the current value or the power value of the drive motor is substantially constant. A threshold based on the current value or power value of the drive motor when the rotary dresser contacts substantially the entire surface of the grinding wheel, and comparing the current value or power value of the drive motor in the dressing process. And determining the dressing state is good when the current value or the power value of the drive motor in the dressing step is equal to or more than a threshold value, and terminating the dressing step when it is determined that the dressing state is good. A dressing method for a grinding wheel in a centerless grinding machine according to any one of claims 1 to 3, wherein A grinding wheel drive motor for rotating the grinding wheel at substantially the same speed as when grinding, a dresser drive motor for rotating the rotary dresser at a peripheral speed substantially equivalent to the grinding wheel, a slightly faster peripheral speed or a slightly slower peripheral speed, Dress control means for controlling the rotary dresser to cut into the grinding wheel by a predetermined amount each time the entire width of the grinding wheel is traversed a predetermined number of times; and a current value or power value of the dresser drive motor during dressing, the rotary dresser Compared with the threshold value based on the current value or power value of the dresser drive motor when contacting substantially the entire surface of the grinding wheel, the current value or power value of the dresser drive motor during dressing is greater than or equal to the threshold value A dressing device for a grinding wheel in a centerless grinding machine, comprising: a determination means for ending the dressing at the time of (1).

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