JP2005059141A - Grinding method and controller of grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extend grinding whetstone life and to improve roughness of a workpiece surface by suppressing rapid drop of abrasive grains on the whetstone surface due to interference with the workpiece in a grinding process. <P>SOLUTION: A force sensor 40 detects working resistance varying in response to increase of incising amount of the whetstone from a contact starting time of the whetstone S with the workpiece W by in-process. This controller 61 determines timing of stopping the incising feeding of the whetstone S with reference to the time when the working resistance after the start of the grinding detected by the force sensor 40 reaches a peak, and performs spark out grinding after that time while the relative position of the whetstone S in the incising direction is maintained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for grinding an outer peripheral surface or an inner surface of a rotating workpiece such as a cylinder or a cam, and a control device for a grinding machine.

In general, the method of grinding a rotating workpiece with a grindstone is such that a cutting feed is given to the grindstone at a predetermined speed with respect to the workpiece, and the relative incision position of the grindstone has reached a target point, or the workpiece is ground. Measure the dimensions of the workpiece in-process, detect that the workpiece dimension obtained from the measurement result has reached the target dimension, stop the cutting feed of the grinding wheel, and continue the grinding stone and workpiece for a predetermined time Continue to contact, and finish grinding. In this case, the surface roughness of the workpiece is determined depending on the final contact state between the grindstone and the workpiece and the state of the abrasive grains on the surface portion of the grindstone in contact with the workpiece.

Therefore, if the target surface roughness cannot be obtained after the grinding is completed, the grinding wheel is replaced with a grinding wheel with finer abrasive grains, the grinding motion condition of the grinding stone is changed, or the grinding stone cutting feed is stopped. The current situation is to achieve the target by extending the contact time between the grindstone and the workpiece. Still another method includes adding a similar grinding step using a grindstone with finer abrasive grains after the above grinding step.

When grinding with a grindstone that uses a binder with low abrasive grain retention strength, such as a resinoid type, where the surface portion that comes into contact with the grindstone workpiece is subject to grinding, contact with the grindstone workpiece during grinding In the surface portion, the surface condition is likely to be deteriorated due to dropping off of the abrasive grains, and in such a case, the ability to improve the surface roughness of the workpiece held by the grindstone before grinding is lowered.
JP 2002-187049 A Toyoda Machine Grinder Group, External grinding work you want to know, Japan Machinist, 1982, page 71

The deterioration of the surface condition of the grindstone that occurs in the case of the above-described method is that a cutting feed is given to the rotating grindstone, and the resistance acting on the grindstone gradually increases as the cutting feed continues after the grindstone starts to contact the workpiece. Along with this, the resistance acting on the abrasive grains coming into contact with the workpiece on the surface of the grindstone is eventually caused by dropping off of the abrasive grains resulting from exceeding the support strength of the binder supporting each abrasive grain. It is. In other words, even if the processing resistance acting on the abrasive grains after the start of grinding exceeds the abrasive grain support strength of the binder, the incision feeding of the grindstone is continued, so that the abrasive grains fall off and the grindstone before grinding is held This reduces the ability to improve the surface roughness of the workpiece.

In the present invention, in view of such a situation, by continuing the cutting feed even after the dressed grindstone comes into contact with the workpiece, the abrasive grains on the grindstone surface fall off, and the grindstone before grinding reduces the surface roughness of the workpiece. It is an object of the present invention to provide a grinding method and a grinding apparatus that improve the surface roughness of a workpiece while avoiding a reduction in the ability to improve.

In order to solve the above-mentioned problems, the invention of claim 1 is directed to a processing method for grinding a workpiece with a grindstone by moving the grindstone relative to the workpiece while rotating the grindstone and the workpiece, respectively. After grinding was started and grinding was started, when the surface roughness of the workpiece decreased or the state of the surface part of the grinding wheel that contacted the workpiece changed suddenly, the interference state of the grinding wheel with the workpiece changed. A grinding method and a grinding machine control device for improving the surface roughness of a workpiece by stopping the cutting feed at the time and continuing the grinding state for a set time while maintaining the relative position in the cutting direction of the grindstone as it is.

The grinding method according to claim 2 is the grinding method according to claim 1, wherein the surface roughness of the workpiece or a value corresponding to the surface roughness is measured at the initial stage of the grinding process after the start of grinding, and the surface roughness of the workpiece is measured. Is a grinding method in which the cutting feed of the grinding wheel is stopped and spark-out grinding is performed at the relative position of the grinding wheel in the cutting direction when the surface roughness of the workpiece becomes minimal.

The grinding method according to claim 3 is the same as the grinding method according to claim 1, and the state of the surface of the grindstone that comes into contact with the workpiece in the grinding process is greatly changed due to the relatively weak abrasive grain holding strength of, for example, a fine grindstone or resinoid grindstone. When using an easy-to-use grindstone, in the initial stage of the grinding process after starting grinding with a grindstone that has increased the abrasive cutting edge density on the surface of the grind by dressing, the processing resistance, dimension generation amount or By measuring the amount of grinding phenomenon such as the amount of grinding wheel wear, the grinding wheel is placed at a relative position in the grinding direction of the grinding stone immediately before the ability of the grinding wheel to improve the surface roughness of the workpiece sharply decreases. A grinding method that stops and performs spark-out grinding. That is, this is a grinding method in which spark-out grinding is performed when the machining resistance reaches a peak after the start of grinding, when the dimension of the workpiece starts to decrease, or when the dimension of the grindstone starts to decrease.

In order to enable the grinding method of claim 2, a control device for a grinding machine according to claim 4 measures the surface roughness of the workpiece or the phenomenon amount representing the surface roughness of the workpiece in-process during the grinding process. A measuring means and a cutting motion control means for stopping the cutting feed of the grindstone are provided, and this cutting motion control means is a phenomenon amount representing when the surface roughness of the workpiece becomes minimum or the surface roughness of the workpiece. Is a control device for a grinding machine that controls the timing at which the cutting feed of the grindstone is stopped on the basis of the time when the surface roughness of the workpiece becomes a minimum value.

In order to enable the grinding method of claim 3, the control device of the grinding machine of claim 5 is a value representing a change in the state of interference of the grindstone with the workpiece in the grinding process, for example, machining resistance, dimension of the workpiece or Measuring means for measuring the grinding wheel dimensions in-process during the grinding process and cutting motion control means for stopping the cutting feed of the grinding wheel, and the cutting motion control means, for example, when the machining resistance reaches a peak, the dimensions of the workpiece Is a grinder control device that controls the timing at which the cutting feed of the grindstone is stopped with reference to the time when the wheel starts to decrease or the time when the size of the grindstone starts to decrease.

The grinding method according to claim 6 uses the grinder control device according to claim 4 or claim 5 to stop the cutting feed of the grindstone at a relative position in the cutting direction of the reference grindstone, and then grinds for a predetermined time. Is a grinding method for improving the surface roughness of the workpiece by maintaining the contact state between the workpiece and the workpiece.

As described above, according to the present invention, in the process of grinding the workpiece by applying a cutting feed motion to the dressed grindstone, the abrasive grains on the surface of the grindstone start to fall off due to an increase in processing resistance after the start of grinding. Processing resistance acting on the grindstone by detecting the values representing the deterioration of the grindstone surface condition and determining the timing for stopping the cutting feed of the grindstone on the basis of the time when the fluctuation tendency of those values changes rapidly And the deterioration of the grindstone surface state that occurs when the cutting feed of the grindstone is continued thereafter is suppressed, so that the dressing interval is extended by reducing the wear of the grindstone. In addition, it is possible to extend the life of the grinding wheel as well. There is an effect that it is possible to further reduce the surface roughness of the workpiece as compared with the case to continue.

The best mode for carrying out the present invention will be described with reference to the drawings.

The grinding machine shown in FIG. 1 includes a bed 10 on which a workpiece support table 11 is guided and supported so as to be movable in the horizontal direction (Y direction). A headstock 12 and a tailstock 13 are installed on the table 11 so as to face each other. A workpiece W is supported at one end by a center 14 installed on the spindle stock 12 and the other end of the workpiece W is supported by a tailstock. The workpiece W is supported by a center 15 installed on the table 13, and is installed so as to be rotatable about both center axes.

The spindle W and the tailstock 13 support the workpiece W at both ends so that the rotation axis of the workpiece W is parallel to the horizontal movement direction Y of the table 11, and the workpiece W is rotated by the rotation of the spindle driving motor (not shown). Is designed to rotate.

A fixed table 28 is installed on the bed 10, and a guide rail 29 extending in a predetermined cutting direction (X direction) is laid on the fixed table 28, and can slide along the guide rail 29. A cutting table 32 is provided. The cutting table 32 is slidably driven in the cutting and feeding direction by a servo motor 31 and a feed screw mechanism 30 installed on the fixed table 28.

A grinding wheel base 21 is installed on the cutting table 32, and a grinding wheel shaft 22 extending in a horizontal direction (Y direction) perpendicular to the cutting direction is rotatably supported on the grinding wheel base 21. A disc-shaped grindstone S is fixed to the end. A driven pulley 24 is fixed to the grindstone shaft 22, and a grindstone drive motor 27 is installed on the cutting table 32, and a driving pulley 26 is fixed to an output shaft thereof. The driving pulley 26 and the driven pulley are fixed. A transmission belt 25 is stretched between the pulley 24.

Therefore, in this grinding machine, the grindstone S is driven to rotate at a high speed by the operation of the grindstone drive motor 27, and the workpiece W supported between the headstock 12 and the tailstock 13 by the operation of the servomotor 31. On the other hand, the grindstone S is cut and fed.

Further, in this grinding machine, the machining resistance generated in the cutting direction (X direction) of the grindstone with respect to the grinding point on the surface of the workpiece W along with grinding at the center 15 installed on the tailstock 13 and A force sensor (detection means) 40 for detecting a machining resistance generated in the tangential direction (perpendicular to the paper surface) of the surface at the grinding point is installed so that changes in the machining resistance during the grinding process can be measured in-process. Yes.

The signal detected by the force sensor 40 is input to the grinder control device 61 via the amplifier 40a. The control device 61 includes a signal determination unit 61a and a motor control unit 61b. As will be described later, the signal determination unit (determination means) 61a outputs a determination signal when the machining resistance signal detected by the force sensor 40 gradually increases and reaches a peak after the start of grinding. The control unit (cut feed control unit) 61b stops the rotary motion of the servo motor 31 and the cut motion of the grindstone S at the timing based on the determination signal.

Next, the control operation actually performed by the control device 61 and the operation of the entire device associated therewith will be described with reference to the flowchart of FIG.

First, in the state where the grinding wheel S whose surface abrasive grain cutting edge density has been adjusted by dressing is not in contact with the workpiece W, the grinding wheel drive motor 27 is operated to rotate the grinding wheel S at a high speed, and the workpiece W Also, both the support centers 14 and 15 are rotated at a predetermined speed by the spindle drive motor with the fulcrum as a fulcrum (step S11). Then, the grinding wheel S rotating at a high speed is operated by the servo motor 31 to make a cutting motion with respect to the rotating workpiece W at a predetermined speed, and the workpiece W is ground with the grinding wheel S.

At this time, the force sensor 40 detects in-process a machining resistance that increases as the grinding wheel cutting amount increases from the time when the grinding wheel S and the workpiece W start to contact, and a signal in the control device 61 is passed through the amplifier 42a. A machining resistance signal is transmitted to the determination unit 61a. The machining resistance detected by the force sensor 40, that is, the voltage signal output from the amplifier 42a, is the workpiece of the grindstone S attached to the grindstone table 21 that cuts and feeds at a predetermined speed from the point of contact between the grindstone S and the workpiece W. It increases as the cutting depth for W increases.

However, when the processing resistance that increases as the cutting depth of the grindstone S increases with respect to the workpiece W exceeds the holding strength of the abrasive grains on the surface of the grindstone W, the abrasive grains fall off from the surface of the grindstone W, and The density of the abrasive cutting edge on the surface decreases. At this time, the machining resistance reaches a peak, and thereafter the machining resistance decreases even if the cutting amount of the grindstone W increases. Therefore, the voltage signal input to the signal determination unit 61a also peaks at this time.

The control device 61 monitors the voltage signal changing in this way, and the control device increases the voltage signal from the start of grinding, and the change stagnates and starts to decrease, that is, based on the time point when the peak is reached (step (step)). S13) A signal is transmitted to the motor control unit 61b, and the motor control unit transmits a rotation stop signal to the grinding wheel cutting feed servomotor 31.

Upon receiving the rotation stop signal from the control device 61, the servo motor 31 immediately stops rotating, stops and holds the grindstone at the current position, and continues grinding in that state (step S14). Grinding is finished after the time elapses. In other words, since the processing resistance that increases as the cutting amount of the grinding stone S increases from the start of grinding exceeds the retention strength of the abrasive grains on the surface of the grinding stone S, the abrasive grains that act as cutting edges start to fall off violently. At the time immediately before, that is, when the density of the abrasive grains on the surface of the grindstone S is a straight line, the cutting feed of the grindstone S is stopped, and the grindstone S is left at the relative position in the cutting direction of the grindstone S until the end of grinding. By maintaining a state where the density of the abrasive grains on the surface is high, the surface roughness of the workpiece W can be finished in a better state.

Moreover, by stopping the cutting feed of the grindstone S at a time before the sharp drop of the abrasive grains begins, the processing resistance acting on the grindstone S is reduced from the same point, and more than necessary due to the drop of the abrasive grains. Wear of the grindstone S is prevented, and when the grindstone S is ground, the required number of dressings for restoring the abrasive cutting edge density on the grindstone surface is reduced, and the life of the grindstone can be improved.

The best embodiment of the present invention is not limited to this, and can take the following form, for example.

(1) In the above embodiment, the machining resistance is detected by the force sensor 40 installed in the workpiece support center 15, but it corresponds to the machining resistance by the current sensor 41 installed in the power supply cable of the grindstone drive motor 27. The supply current to be detected may be detected, and the signal may be used as a control reference.

(2) In the above embodiment, the machining resistance that changes with the progress of grinding is measured in-process by a sensor, and the cutting feed of the grindstone is stopped on the basis of the time when the machining resistance reaches the peak. As shown in FIG. 1, a dimension detection sensor (detection means) 42 for measuring a change in the grinding amount (radius reduction amount of the workpiece W) in the grinding process in-process is installed using the workpiece holding table 11 as a base. Further, the cutting feed of the grindstone may be stopped immediately after the radius reduction amount of the workpiece W detected by the sensor or the speed thereof increases to a certain threshold value. In this case, the mounting position of the same dimension detection sensor is a position where the dimension of the workpiece W can be detected as close as possible to the grinding point on the grinding surface of the workpiece W, and a change in the dimension of the workpiece due to grinding is immediately detected. It is desirable to do. The detection method of the dimension detection sensor (detection means) 42 is a contact method or a non-contact method.

The control operation actually performed by the control device 67 in this case and the operation of the entire device associated therewith are shown in the flowchart of FIG. As in the case of FIG. 2 in which the machining resistance is determined, the grindstone S whose surface abrasive grain cutting edge density is adjusted by dressing is cut and fed to the workpiece W at a predetermined speed. The object W is ground. In this case, as will be described later, by determining when the dimension of the workpiece W starts to decrease (step S23), the change in the surface of the grindstone due to grinding as described above is grasped, and the cutting feed of the grindstone is immediately stopped. (Step S24), spark out grinding is performed.

(3) In the above embodiment, the change in the physical quantity in the workpiece W accompanying the progress of grinding is measured in-process, and the timing for stopping the cutting motion of the grindstone S is determined based on the detection signal. A signal output by in-process measurement of a change in physical quantity in the above may be used as an object for determining the timing of the cut feed stop. For example, as shown in FIG. 1, a dimension detection sensor (detection means) 43 for measuring a change in radius reduction amount (wear amount) of the grinding wheel S in the grinding process is installed on the basis of the grinding wheel base 21, and the sensor The cutting infeed of the grindstone may be stopped immediately after the radius reduction amount or the speed of the grindstone S detected by the above reaches a certain threshold value and the sign of a sharp grindstone wear is confirmed.

(4) In the above-described embodiments, the cutting motion control of the grindstone S is performed for the physical quantity associated with the grinding phenomenon that occurs in the grinding process. However, the surface roughness of the workpiece to be improved in the present invention is directly input. The process may be measured, and the output signal may be used as a target for determining the timing of stopping the cutting feed. For example, as shown in FIG. 1, a surface roughness detection sensor or a micro displacement sensor (detection means) 44 for measuring a change in the surface roughness of the workpiece W in the grinding process in-process is provided with a workpiece holding table 11. And the cutting motion of the grindstone may be stopped immediately after the surface roughness of the workpiece W detected by the sensor or the surface roughness change speed increases to a certain threshold value.

(5) The above embodiment can be similarly applied to internal grinding or centerless grinding.

FIG. 4 shows the surface roughness Ry, machining resistance p, q, and grindstone cutting when the workpiece having a surface roughness of about 2.5 μm Ry is ground under the following conditions in the apparatus shown in FIG. The time variation of the amount d and the radius reduction amount R of the workpiece is shown in the graph.

Grinding wheel: GC320N5M13B (φ400 × 50mm)
Workpiece: SUS304 (φ100 × 10mm)
Wheel peripheral speed: 31.8m / s
Workpiece peripheral speed: 0.6m / s
Grinding wheel cutting feed rate: 1.0 μm / s
Grinding system rigidity: 11.14 N / μm
Polishing fluid: W2 type 1 (80 times dilution)
Dressing tool: Impreza Dressing condition: After 3 passes at 5μm depth, 2 passes at 0μm

As apparent from FIG. 4, the surface roughness of the workpiece W, which is about 2.5 μm Ry before grinding, suddenly decreases from the start of grinding, and reaches a minimum at about 7 s after grinding starts. It turns around and increases rapidly. After that, when the surface roughness of the workpiece W becomes constant, if grinding is continued (spark-out grinding) with the cutting feed of the grindstone stopped, the final surface roughness of the workpiece W is about 1.4 μmRy. However, it does not reach the surface roughness 1.1 μm Ry of the workpiece W that has become minimum at about 7 s after the start of grinding. In addition, if the cutting feed of the grindstone S is stopped and the spark-out grinding is performed when the surface roughness of the workpiece W becomes the minimum, the surface roughness of the workpiece W becomes further smaller and finally becomes 1.0 μmRy. Will be improved.

On the other hand, the machining resistance rapidly increases as the cutting amount of the grindstone S increases after the grinding starts. When the value reaches a peak, the cutting resistance of the grindstone S continues to increase and then decreases. The time when the surface roughness of the object W is minimized coincides with the time when the machining resistance takes a peak value.

FIG. 5 shows the cutting amount d of the grindstone S in the case of grinding up to 15 s after the time when the surface roughness of the workpiece W takes the minimum value from the start of grinding in the grinding process shown in FIG. The change process of the radius reduction amount R and the wear amount do of the grindstone S is shown in the graph. The time point of the black plot in the figure indicates the time point when the surface roughness of the workpiece W is minimized. Immediately after the start of grinding, both the radius reduction amount R of the workpiece W and the wear amount do of the grindstone S are almost zero, but the point in time when the surface roughness of the workpiece W indicated by the black plot in the figure becomes minimum is approaching. Then, both the radius reduction amount R of the workpiece W and the wear amount do of the grindstone S begin to gradually increase, and the wear amount do of the grindstone S increases rapidly when the surface roughness of the workpiece W reaches a minimum. In addition, it can be predicted that the sharp increase in the wear amount do of the grindstone S is caused by a sudden drop of the abrasive cutting edge on the surface of the grindstone S.

Further, FIG. 6 shows the time change of the surface roughness Ry of the workpiece W when it is ground with the grindstone S as in FIG. The graph shows the value of the surface roughness Ryf of the workpiece W after the cutting feed of the grindstone S is stopped and the spark-out grinding is performed for a predetermined time at each grinding point of the plot. As is apparent from this drawing, the surface roughness of the workpiece W is most improved by performing the spark-out grinding by stopping the cutting feed of the grindstone S during the grinding process. This is a case where switching to spark-out grinding is performed when the roughness becomes minimum.

Therefore, for example, when the surface roughness of the workpiece W takes a minimum value, when the machining resistance reaches a peak, when the radius reduction amount of the workpiece W starts to increase, or when the wear amount of the grindstone S increases. While increasing the time point, etc., by monitoring the respective values and stopping the cutting feed of the grindstone, while suppressing deterioration of the surface of the grindstone S having a relatively high abrasive density after dressing, It is possible to improve the surface roughness of the workpiece W by exerting the maximum surface finishing capability of the grindstone.

INDUSTRIAL APPLICABILITY The present invention has a possibility of being used in a manufacturing process of a machine part having a precision cylindrical surface or a precision hole whose main purpose is to improve surface roughness and a grinding machine that realizes the manufacture.

1 is an overall configuration diagram showing a grinding machine and its control device according to an embodiment of the present invention. It is a flowchart which shows the control operation which a control apparatus performs with the signal from the force sensor provided in the said grinding machine. It is a flowchart which shows the control operation | movement which a control apparatus performs by the signal from the displacement sensor which detects the workpiece radius reduction amount provided in the said grinding machine. It is a graph which shows the time change of the workpiece surface roughness from the grinding | polishing start, a process resistance, and a workpiece radius reduction amount when cutting and feeding a grindstone. It is a graph which shows the time change of the workpiece radius reduction amount from the grinding | polishing start, and the grinding wheel wear amount when cutting and feeding a grindstone and grinding a workpiece. The time change of the surface roughness of the workpiece from the start of grinding when the workpiece is ground by cutting and feeding the grinding wheel, and the final surface roughness of the workpiece when the grinding and cutting out of the grinding stone is stopped and the spark-out grinding is performed from each grinding point. It is a graph which shows the change of height.

Explanation of symbols

S Whetstone W Workpiece 21 Whetstone stand 27 Whetstone drive motor 31 Servo motor 40 for cutting feed Force sensor (detection means)
41 Current sensor (detection means)
42 Displacement sensor (detection means)
43 Displacement sensor (detection means)
44 Surface roughness detection sensor (detection means)
61a Signal determination unit (determination means)
61b Motor controller (cutting feed stop means)

Claims (6)

In the processing method of grinding the workpiece by the grindstone by rotating the grindstone and the workpiece relative to each other while rotating the grindstone and the workpiece, the grindstone is cut and fed to start grinding. Infeed feed when the surface roughness of the workpiece decreases or immediately before the state of the surface portion of the grindstone that contacts the workpiece suddenly changes and the state of interference of the grindstone with the workpiece changes. A grinding method and a grinding machine control device for improving the surface roughness of the workpiece by continuing grinding for a set time while maintaining the relative position in the cutting direction of the grindstone as it is . 2. The grinding method according to claim 1, wherein the surface roughness of the workpiece or a value corresponding to the surface roughness is measured in-process at an initial stage of the grinding process after the start of grinding, and the surface roughness of the workpiece is temporarily reduced. Then, the grinding method is characterized in that spark-out grinding is performed by stopping the cutting feed of the grindstone at a relative position in the cutting direction of the grindstone when the surface roughness of the workpiece reaches a minimum. In the grinding method according to claim 1, for example, when a grindstone having a relatively weak abrasive grain holding strength, such as a fine grindstone or a resinoid grindstone, is used as the grindstone, the state of the grindstone surface portion that comes into contact with the workpiece by grinding is easily changed. In the initial stage of the grinding process after the start of grinding, the grinding wheel is measured in-process by measuring the amount of grinding phenomenon such as grinding resistance, dimension generation amount or grinding wheel wear amount that represents the interference state of the grinding wheel with the workpiece. A grinding method of performing spark-out grinding by stopping the cutting feed of the grinding wheel at a relative position in the cutting direction of the grinding stone at a time immediately before the ability to improve the surface roughness of the workpiece is sharply reduced. That is, when the grinding resistance reaches a peak after starting grinding, when the dimension of the workpiece starts to decrease, when the radius reduction amount of the workpiece reaches a certain threshold, or when the dimension of the grindstone starts to decrease. A grinding method characterized by starting spark-out grinding at a time point. In order to enable the grinding method according to claim 2, measuring means for measuring in-process the surface roughness of the workpiece or the phenomenon amount representing the surface roughness of the workpiece in a grinding process, and cutting feed of the grinding wheel A cutting motion control means for stopping the workpiece, and the cutting motion control means is configured so that a phenomenon amount indicating the surface roughness of the workpiece is the time when the surface roughness of the workpiece is minimized or the surface roughness of the workpiece. A control device for a grinding machine, characterized by controlling a timing at which the cutting feed of the grindstone is stopped on the basis of a time point at which the roughness becomes a minimum value. In order to enable the grinding method according to claim 3, a value representing a change in an interference state of the grindstone with the workpiece in the grinding process, for example, a grinding resistance, a dimension of the workpiece, or a dimension of the grindstone in the grinding process. Measuring means for in-process measurement and cutting motion control means for stopping the cutting feed of the grindstone, and this cutting motion control means, for example, when the grinding resistance reaches a peak, when the dimension of the workpiece starts to decrease Alternatively, the grinder control device controls the timing for stopping the cutting feed of the grindstone on the basis of the time when the size of the grindstone starts to decrease. Using the grinder control device according to claim 4 or 5, the grindstone and the workpiece of the workpiece for a predetermined time while the cutting feed of the grindstone is stopped at a relative position in the cutting direction of the grindstone as a reference. A grinding method characterized in that the surface roughness of the workpiece is improved by continuing the contact state.

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