JP2013116534A - Grinding method and grinding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding machine capable of performing grinding at desired grinding accuracy in the shortest possible grinding time in a finishing grinding irrespective of variations in grinding rigidity.SOLUTION: In the course of a continuous grinding method in which workpieces W of the identical shape are subjected to the step of a continuous grinding, the grinding rigidity is measured in the grinding step of an initial grinding cycle S5 which is a grinding cycle for a workpiece to be initially ground. In the following grinding cycle S6 which is a grinding cycle for workpieces to be ground next and thereafter, a rough grinding step is first carried out, and after that, a grinding rigidity measured during the grinding of a workpiece ground before the present workpiece, a normal grinding force measured during the rough grinding step, and a grinding amount in the final grinding step for the present workpiece are made to calculate a retracting amount. After retracting grinding is performed that makes a retracting wheel retracted only by the retracting amount, the final grinding step is practiced so that the grinding rigidity in the final grinding step is measured.

Description

  The present invention relates to a grinding method and a grinding machine for grinding while retreating a grinding wheel during cylindrical grinding.

  In the grinding process, the workpiece diameter is reduced and ground while the processed part is cut into a spiral shape. In order to make this spiral shape into a perfect circle in a short time, a finish grinding step may be carried out after a reverse grinding step. In this backward grinding cycle, the backward position in the backward grinding process is set to a position where there is no deflection, and the grinding wheel is cut and ground again from the state where there is no deflection in the finish grinding process. Furthermore, in order to shorten the time required for finish grinding, it has been proposed that the retracted position in the backward grinding process is a position where a deflection corresponding to the depth of cut per work rotation during finish grinding occurs (patent) Reference 1).

JP-A-7-214466

  In finish grinding, it is necessary to rotate the workpiece by a predetermined number of rotations in order to ensure a predetermined accuracy. In the technique described in Patent Document 1, the variation of the cutting amount per rotation of the workpiece due to the change of the grinding rigidity is not taken into consideration. For this reason, in order to set the rotation speed of the workpiece in the finish grinding to a predetermined value or more, a bending position with a margin is set. As a result, the finish grinding time becomes longer.

  The present invention has been made in view of the above circumstances, and by determining the retraction amount of the grinding wheel in the reverse grinding according to the grinding rigidity, the desired grinding can be performed in the shortest grinding time in the finish grinding regardless of the change in the grinding rigidity. An object of the present invention is to provide a grinding machine capable of grinding with high grinding accuracy.

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a grinding wheel is cut in a radial direction of the cylinder by rotatably supporting a workpiece having a cylindrical machining portion around the axis of the cylinder. In a grinding method for continuously grinding workpieces of the same shape using a grinding machine
The subsequent grinding cycle, which is the grinding cycle of the workpiece to be ground after the second,
A second grinding step having a predetermined cutting speed of the grinding wheel;
A reverse grinding step in which the grinding wheel is ground while moving backward in a direction away from the workpiece, which is performed immediately before the second grinding step;
A first grinding step that is performed immediately before the reverse grinding step, and has a cutting speed of the grinding wheel that is greater than a cutting speed of the grinding wheel in the second grinding step;
The amount of retraction in the reverse grinding process is measured in the first grinding process, which is the grinding rigidity, which is the ratio of the actual cutting depth measured during grinding of the workpiece ground before the workpiece and the normal grinding resistance. A first normal grinding resistance which is either a normal normal grinding resistance or a normal grinding resistance calculated from the cutting speed of the grinding wheel in the first grinding step, and the second grinding of the workpiece Retraction amount calculation process that calculates from the target grinding amount of the process,
A second grinding rigidity measuring step of measuring the grinding rigidity in the second grinding step.

A feature of the invention according to claim 2 is that a workpiece having a cylindrical machining portion is rotatably supported around an axis of the cylinder, and a grinding wheel is cut in a radial direction of the cylinder so that the workpiece having the same shape is obtained. In grinding machines that continuously grind,
A grinding wheel cutting device for moving the grinding wheel in the radial direction of the cylinder;
A workpiece diameter measuring device for measuring a diameter dimension of the processed portion;
Normal force measuring means for measuring normal grinding resistance force during grinding;
Grinding rigidity calculating means for calculating the grinding rigidity as a ratio of the actual cutting amount measured by the workpiece diameter measuring device and the normal grinding resistance force measured by the normal force measuring means;
Retraction amount calculation means for calculating a retraction amount using the grinding rigidity, normal grinding resistance, mechanical rigidity, and target grinding amount calculated by the grinding rigidity calculation means;
In the subsequent grinding cycle, which is the grinding cycle of the workpiece to be ground after the second,
Perform the first grinding process,
Performing a reverse grinding step of moving the grinding wheel by a retraction amount in a direction away from the workpiece;
The grinding wheel has a cutting speed smaller than the grinding wheel cutting speed in the first grinding step, the second actual cutting amount is measured by the workpiece diameter measuring device, and the second normal resistance is measured by the normal force measuring means. The second grinding process to measure the force,
The retraction amount is determined by grinding rigidity measured during grinding of the workpiece ground before the workpiece, normal grinding resistance measured in the first grinding step, or the grindstone in the first grinding step. Using the first normal grinding resistance, which is one of the normal grinding resistances calculated from the vehicle cutting speed, and the target grinding amount of the workpiece in the second grinding process, the reverse amount calculation means calculates And
In order to calculate the second grinding rigidity, which is the grinding rigidity in the second grinding step, using the second actual cutting amount and the second normal resistance force,
A control device for controlling the grinding wheel cutting device, the workpiece diameter measuring device, the normal force measuring means, the grinding rigidity calculating means, and the retraction amount calculating means;
It is to provide.

  According to the first aspect of the present invention, it is possible to set the retraction amount in the reverse grinding process of the workpiece to be ground after the second one to an amount corresponding to the current grinding rigidity. For this reason, the grinding time, the grinding accuracy, etc. in the second grinding process can be set to desired constant values without being affected by the change in grinding rigidity.

  According to the second aspect of the present invention, it is possible to set the retraction amount in the reverse grinding process of the workpiece to be ground after the second one at a position corresponding to the current grinding rigidity. For this reason, the grinding machine which can make the grinding time in a 2nd grinding process, grinding precision, etc. desired fixed value can be provided.

It is the schematic which shows the whole structure of the grinding machine of this embodiment. It is a B arrow line view of FIG. It is a figure which shows the change of the workpiece radius of finish grinding. It is a figure which shows the positional relationship of the workpiece and grinding wheel in reverse grinding. It is a flowchart which shows the continuous grinding cycle of this embodiment. It is a flowchart which shows the initial stage grinding cycle of this embodiment. It is a flowchart which shows the subsequent grinding cycle of this embodiment. It is a flowchart which shows the grinding-rigidity measurement process of this embodiment. It is a figure which shows the concept of the grinding rigidity measurement of this embodiment.

Hereinafter, embodiments of the present invention will be described based on examples of cylindrical grinding machines.
As shown in FIG. 1, a cylindrical grinding machine 1 includes a bed 2 and is supported on a bed 2 so as to be reciprocable in the X-axis direction and driven by a feed motor (grinding wheel cutting device) 8. A vehicle cutting device) 3 and a table 4 that can reciprocate in the Z-axis direction orthogonal to the X-axis. The grinding wheel base 3 rotatably supports the grinding wheel 7, and the grinding wheel 7 is rotationally driven by a grinding wheel shaft rotating motor (not shown). On the table 4, a spindle 5 provided with a phase detector 9 that grips one end of the workpiece W and rotatably supports it and is rotationally driven by a spindle motor (not shown) to detect the rotational phase of the spindle; A tailstock 6 that rotatably supports the other end of the workpiece W is provided. The workpiece W is supported by the main shaft 5 and the tailstock 6 and is rotationally driven during grinding. A workpiece diameter measuring device 10 for measuring the diameter of the processed portion of the workpiece W is installed on the table.
As shown in FIG. 2, the workpiece diameter measuring device 10 includes a diameter measuring device main body 101 held by a base 11 fixed to a table, and a diameter measuring device main body 101 engaged with an axis of the workpiece W. The contacts 102a and 102b are arranged to face each other by 180 °. Here, the facing directions of the contacts 102a and 102b are arranged so as to intersect with the X axis at an angle of Φ.

  The cylindrical grinding machine 1 includes a control device 30. As a functional configuration of the control device 30, an X-axis control unit 31 that controls the feed of the grindstone table 3, a Z-axis control unit 32 that controls the feed of the table 4, A spindle control unit 33 that controls the rotation of the spindle 5, a measuring device control unit 34 that controls the workpiece diameter measuring device 10, an arithmetic unit 35, and the like are provided. As functions of the X-axis control unit 31, a normal grinding resistance measurement unit 311 that measures a normal grinding resistance force acting on the grinding wheel 7 during grinding from a current value of the motor 8, and a position of the grinding wheel base from the rotational phase of the motor 8. A grinding wheel position detecting unit 312 is provided. As functions of the calculation unit 35, there are provided a grinding stiffness calculation means 351 for calculating the grinding stiffness, a retraction amount calculation means 352 for calculating a retraction amount, and a recording unit 353 for recording measured values and target values.

  Here, the characteristics of finish grinding, which is the final grinding step with the cutting of the grinding wheel 7 in the grinding cycle, will be described. In finish grinding, it is desirable that the workpiece W can be ground to the desired diameter value, roundness and surface roughness in the shortest time, that is, the minimum number of rotations of the workpiece W at which these values reach the desired value is set. I can do it. The roundness and the surface roughness can be set to desired values by setting the amount of workpiece removal per rotation of the workpiece W to a predetermined value or less and rotating the workpiece W a predetermined number of times. On the other hand, the number of rotations of the workpiece necessary for setting the diameter of the workpiece W to a predetermined value varies depending on the grinding rigidity value. Grinding rigidity is the ratio of the actual cutting amount U, which is the actual cutting amount of the grinding wheel 7 to the workpiece W in the grinding part, and the normal grinding resistance force F acting at that time. F / U. If the grinding rigidity is high, the normal grinding resistance required for grinding with the same actual cutting depth increases, and it is said that the sharpness is poor. Usually, the grinding rigidity gradually changes due to falling off or wear of abrasive grains on the grinding surface caused by grinding.

FIG. 3 shows how the workpiece radius changes when the grinding rigidity is different. A straight line indicated by a solid line a in FIG. 3 is a case where the grinding rigidity is low, and a curve indicated by a broken line b is a case where the grinding rigidity is high. When finishing the relative deflection of T ₁ of the grinding start time of the workpiece W and the grinding wheel 7 is the same, the normal force F ₁ acting at the finish grinding start are the same proportional to the deflection amount T ₁ . When the grinding rigidity indicated by the solid line a is small, it is assumed that the actual cutting amount U ₁ is equal to the command cutting amount ΔV per rotation of the workpiece of the grinding wheel 7. In this case, the same amount is ground per one rotation of the workpiece, and 4 × U ₁ which is the radius removal amount in finish grinding is removed by grinding after four rotations to reach the finished dimension.
On the other hand, if grinding rigidity shown by the broken line b is large, the actual grinding depth U ₂ initial is smaller than the command infeed amount [Delta] V, while increasing the rotation as bending and the normal grinding force of the workpiece, workpiece 4 rotates When the bending deflection reaches T ₂ and the normal resistance force becomes F ₂ , the actual cutting amount U ₁ is equal to the command cutting amount ΔV of the grinding wheel 7. Thereafter, the same amount is ground per revolution of the workpiece and after two revolutions, the finished dimensions are reached.
As described above, when the grinding rigidity is different, the number of rotations of the workpiece necessary for obtaining a predetermined workpiece diameter is different. If the grinding rigidity is high, the number of rotations increases, so the grinding time becomes long.If the grinding rigidity is too low, the finished dimensions are reached before the required number of rotations, and the surface roughness and roundness may not be secured. is there.
The present invention starts the finish grinding by setting the retraction amount of the grinding wheel 7 in the reverse grinding (reverse grinding step) performed immediately before the finish grinding (second grinding step) according to the grinding rigidity at that time. The amount of deflection T ₁ at the time is set to a value at which an appropriate normal resistance is generated, and the actual cutting amount U ₁ at the time of finish grinding and the number of rotations of the workpiece necessary to reach the finished workpiece diameter are set to desired values. Is.

Next, the backward grinding will be described with reference to FIG.
FIG. 4A shows the positional relationship between the workpiece W and the grinding wheel 7 at the end of the rough grinding (first grinding step). Here, the point O is bent (the bending occurs in both the workpiece W and the grinding wheel 7). The sum is relative bending, but the effect is the same even if the grinding wheel 7 is not bent and only the workpiece W is bent by the relative bending amount. Therefore, in the following description, it is described that only the workpiece W is bent. ) Is the center of rotation of the workpiece W, and the point Ot is the center of rotation of the workpiece W during grinding. Point O and a deflection amount T ₁ the distance between the point Ot, distance of the surface position of the point O and the grinding wheel 7 is commanded cut position V ₁ of the grinding wheel 7. Normal grinding resistance force acting at this time is F _1, the actual depth of cut at this time is U _1. The relationship between the deflection T ₁ and the normal grinding resistance force F ₁ can be expressed as T ₁ = F ₁ / km using the mechanical stiffness km, which is the spring constant between the workpiece W and the grinding wheel 7. FIG. 8B shows the positional relationship between the workpiece W and the grinding wheel 7 at the end of backward grinding (at the start of the second grinding process). The deflection amount is T ₂ and the command cutting position of the grinding wheel 7 is V ₂ . The wire grinding resistance is F ₂ and the actual cutting depth is U ₂ .

The workpiece radius R ₂ in the retracted position only needs to be smaller than the workpiece radius R ₁ at the end of rough grinding in FIG. 4A by the actual cutting amount U ₂ in finish grinding (second grinding process). . That is, R ₁ = R ₂ + U ₂ , R ₁ = T ₁ + V ₁ , R ₂ + U ₂ = T ₂ + V ₂ + U ₂ , and T ₁ + V ₁ = T ₂ + V ₂ + U ₂ .
From the above, the retraction amount Vb of the grinding wheel 7 in the reverse grinding process from the end of rough grinding to the start of finish grinding is Vb = V ₂ −V ₁ = T ₁ −T ₂ −U ₂ . Here, since the normal resistance force F _{2 at} which the actual cutting amount in the grinding rigidity kg is U ₂ is F ₂ = U ₂ × kg = T ₂ × km, T ₂ = U ₂ × kg / km. Also, T ₁ = F ₁ / km. When T ₁ and T ₂ are replaced, Vb = V ₂ −V ₁ = T ₁ −T ₂ −U ₂ = F ₁ / km−U ₂ × kg / km−U ₂ .
Eventually, the retraction amount Vb can be obtained from the normal grinding resistance force F ₁ at the end of rough grinding, the mechanical stiffness km, the actual cutting amount U ₂ in finish grinding, and the grinding stiffness kg in finish grinding. Normal grinding resistance force F ₁ is measured at the rough grinding completion, mechanical stiffness km is measured beforehand by pre-testing, the actual grinding depth U ₂ may be input to a desired value. Although the grinding rigidity kg in the finish grinding cannot be obtained in advance, the amount of change caused by grinding one workpiece is small, so the value of the grinding rigidity kg in the last finish grinding may be used.

As an example of the measurement of the mechanical stiffness km, there is the following method. The grinding wheel 7 and the workpiece W are brought into contact with the grinding wheel 7 stopped, the current value A ₀ of the motor 8 at that time is recorded, and the grinding machine 3 is stopped after cutting the grinding wheel table 3 by a predetermined amount Vg. It records the current value _{a 1} of the. The mechanical stiffness km in this case can be calculated as km = C × (A ₁ −A ₀ ) / Vg, where C is the thrust constant of the motor.

Below, the grinding method which grinds the workpiece W continuously in this grinding machine 1 is demonstrated.
Advance by entering mechanical stiffness km, workpiece rotation speed, the rough grinding completion diameter, medium finishing grinding completion diameter, fine grinding completion diameter, and the actual grinding depth U ₂ during finish grinding to the recording unit 353.
First, the main process will be described based on the flowchart of FIG. The grinding wheel 7 is rotated (S1). It is determined whether or not the continuous cycle is completed. If completed, the process proceeds to step S10, and if not completed, the process proceeds to step S3 (S2). An unground workpiece W is carried in (S3). It is determined whether the grinding wheel has been corrected. If it is just after correction, it will move to step S5, otherwise, it will move to step S6 (S4). After performing the initial grinding cycle (details will be described later), the process moves to step S7 (S5). A subsequent grinding cycle (details will be described later) is performed (S6). The workpiece after grinding is carried out (S7). Judge whether or not the grinding wheel needs to be corrected. If grinding wheel correction is necessary, the process moves to step S9, and if not necessary, the process moves to step S2 (S8). After executing the grindstone correction cycle, the process moves to step S2 (S9). The end processing of the continuous grinding cycle is performed, and the continuous cycle is ended (S10).

The initial grinding cycle will be described based on the flowchart of FIG.
The grinding wheel 7 is cut at a rapid feed to the rough grinding start position (S20). When the grinding wheel 7 is cut at the rough grinding cutting speed, the diameter of the workpiece W reaches the first rough grinding final diameter, and the first rough grinding end signal is output from the workpiece diameter measuring device 10, the rough grinding cutting is finished. (S21). When the grinding wheel 7 is cut at the intermediate finishing grinding cutting speed, the diameter of the workpiece W reaches the intermediate finishing grinding end diameter, and the intermediate finishing grinding end signal is output from the workpiece diameter measuring device 10, the intermediate finishing grinding cutting ends. (S22). Start the finish grinding process. The grinding wheel 7 is cut at the finish grinding cutting speed (S23). A grinding rigidity measurement step (details will be described later) is performed (S24). When the diameter of the workpiece W reaches the finishing diameter and a finishing grinding end signal is output from the workpiece diameter measuring apparatus 10, the finishing grinding process is finished (S25). The grinding wheel 7 is fast-forwarded and retracted (S26).

The subsequent grinding cycle will be described based on the flowchart of FIG.
The grinding wheel 7 is moved forward by rapid traverse (S30). The grinding wheel 7 is cut at the cutting speed at the rough grinding (first grinding step) (S31). When the diameter of the workpiece W reaches the normal resistance measurement start diameter and a normal resistance measurement start signal is output from the workpiece diameter measuring device 10, the normal grinding resistance force F ₁ is calculated from the current value of the motor 8 to the normal resistance. The measurement is performed by the measurement unit 311 and recorded in the recording unit 353 (S32). The retraction amount Vb of the grinding wheel 7 in the reverse grinding step is calculated by the retraction amount calculating means 352 using the formula Vb = F ₁ / km−U ₂ × (kg / km + 1) and recorded in the recording unit 353 (S33). When the diameter of the workpiece W reaches the second rough grinding end diameter and a second rough grinding end signal is output from the workpiece diameter measuring apparatus 10, the rough grinding step (first grinding step) is ended (S34). Perform reverse grinding. While the workpiece is rotated once, the grinding wheel 7 is moved backward by Vb (S35). Finish grinding (second grinding step) is started, and the grinding wheel 7 is cut at the finish grinding cutting speed (S36). A grinding rigidity measurement step (details will be described later) is performed (S37). When the diameter of the workpiece W reaches the finishing diameter and a finishing grinding end signal is output from the workpiece diameter measuring apparatus 10, finishing grinding is finished (S38). The grinding wheel 7 is fast-forwarded and retracted (S39).

The grinding stiffness measurement process will be described based on the flowchart of FIG. 8 and the conceptual diagram of the grinding stiffness measurement of FIG.
As shown in FIG. 9A, the workpiece between a point A that contacts the contact 102a of the workpiece diameter measuring apparatus 10 and a point B that faces the point A and is 180 degrees opposite to the workpiece rotation axis. things diameter _{D 1,} measured by the workpiece diameter measuring device 10 is recorded in the recording unit 353 (S50). The workpiece W is rotated by Φ ° so that the point A is positioned at the grinding portion (S51). As shown in FIG. 9 (b), the normal grinding resistance F ₂ when the point A is ground in the grinding action part is measured and recorded in the recording part 353. Normal grinding force F ₂ is calculated by the product of the current value Am flowing when the the thrust constant C of the motor 8 (S52). The workpiece W is rotated by (180−Φ) ° (S53). As shown in FIG. 8 (c), at a position where the contact 102a and the point B of the workpiece diameter measuring device 10 contacts was measured by the workpiece diameter measuring device 10 the workpiece diameter D ₂ is recorded in the recording unit 353 (S54).
Through the above series of measurements, the workpiece diameter D ₁ before grinding the point A and the workpiece diameter D ₂ after grinding can be measured, and the value of the workpiece diameter D ₂ is subtracted from the value of the workpiece diameter D _1. Thus, the amount by which the point A is ground, that is, the actual cutting amount U with respect to the workpiece W of the grinding wheel 7 can be measured, and U = D ₁ −D ₂ . Further, it is possible to measure the normal grinding resistance force F ₂ in the grinding point A in step S52. The grinding rigidity kg is a ratio between the actual cutting amount and the normal grinding force, and can be obtained by the equation Kg = F ₂ / U.
The grinding rigidity kg is calculated by the expression kg = F ₂ / (D ₁ -D ₂ ) by the grinding rigidity calculating means 351, and the value of the grinding rigidity value in the recording unit 353 is overwritten. (S55).

  As described above, when the continuous grinding method of the present invention is used, when a workpiece having the same shape is continuously ground, the finish is not affected by the change in grinding rigidity due to the state of the grinding surface of the grinding wheel 7. The amount of grinding per rotation in grinding and the number of rotations of the workpiece until reaching the finishing diameter can be made the same. For this reason, a workpiece with a desired accuracy can be ground in a predetermined grinding time.

(Other embodiments)
In the above example, the example in which the present invention is applied to grinding of a cylindrical outer diameter has been described, but it can also be applied to internal grinding.
Further, erosion of the retraction grinding process, has been calculated using the normal value of the grinding resistance F ₁ measured in the rough grinding step immediately before, the normal grinding measured in the rough grinding step of the one previous workpiece The resistance force F ₁ may be used for the calculation, or the normal grinding resistance force F ₁ obtained by the product of the grinding rigidity measured immediately before and the cutting amount of the grinding wheel 7 per rotation of the workpiece in rough grinding. You may calculate using. In this way, the continuous grinding method can be implemented without requiring time for calculating the retraction amount during the grinding cycle.

W: Workpiece 3: Whetstone stand 4: Table 5: Spindle 6: Tailstock 7: Whetstone wheel 8: Motor 9: Phase detector 10: Workpiece diameter measuring device 30: Control device 31: X-axis control unit 35: Arithmetic units 102a and 102b: Contacts 311: Normal force measuring means 312: Grinding wheel position detecting unit 351: Grinding rigidity calculating means 352: Retraction amount calculating means 353: Recording unit

Claims (2)

A workpiece having a cylindrical processing part is rotatably supported around the axis of the cylinder and a grinding wheel for cutting a grinding wheel in the radial direction of the cylinder is used to continuously grind the workpiece having the same shape. In the grinding method,
The subsequent grinding cycle, which is the grinding cycle of the workpiece to be ground after the second,
A second grinding step having a predetermined cutting speed of the grinding wheel;
A reverse grinding step in which the grinding wheel is ground while moving backward in a direction away from the workpiece, which is performed immediately before the second grinding step;
A first grinding step that is performed immediately before the reverse grinding step, and has a cutting speed of the grinding wheel that is greater than a cutting speed of the grinding wheel in the second grinding step;
The amount of retraction in the reverse grinding process is measured in the first grinding process, which is the grinding rigidity, which is the ratio of the actual cutting depth measured during grinding of the workpiece ground before the workpiece and the normal grinding resistance. A first normal grinding resistance which is either a normal normal grinding resistance or a normal grinding resistance calculated from the cutting speed of the grinding wheel in the first grinding step, and the second grinding of the workpiece Retraction amount calculation process that calculates from the target grinding amount of the process,
A grinding method comprising a second grinding stiffness measuring step for measuring grinding stiffness in the second grinding step. In a grinding machine for grinding and grinding a workpiece having the same shape continuously by rotating and supporting a workpiece having a cylindrical processing portion around the axis of the cylinder and cutting a grinding wheel in a radial direction of the cylinder.
A grinding wheel cutting device for moving the grinding wheel in the radial direction of the cylinder;
A workpiece diameter measuring device for measuring a diameter dimension of the processed portion;
Normal force measuring means for measuring normal grinding resistance force during grinding;
Grinding rigidity calculating means for calculating the grinding rigidity as a ratio of the actual cutting amount measured by the workpiece diameter measuring device and the normal grinding resistance force measured by the normal force measuring means;
Retraction amount calculation means for calculating a retraction amount using the grinding rigidity, normal grinding resistance, mechanical rigidity, and target grinding amount calculated by the grinding rigidity calculation means;
In the subsequent grinding cycle, which is the grinding cycle of the workpiece to be ground after the second,
Perform the first grinding process,
Performing a reverse grinding step of moving the grinding wheel by a retraction amount in a direction away from the workpiece;
The grinding wheel has a cutting speed smaller than the grinding wheel cutting speed in the first grinding step, the second actual cutting amount is measured by the workpiece diameter measuring device, and the second normal resistance is measured by the normal force measuring means. The second grinding process to measure the force,
The retraction amount is determined by grinding rigidity measured during grinding of the workpiece ground before the workpiece, normal grinding resistance measured in the first grinding step, or the grindstone in the first grinding step. Using the first normal grinding resistance, which is one of the normal grinding resistances calculated from the vehicle cutting speed, and the target grinding amount of the workpiece in the second grinding process, the reverse amount calculation means calculates And
In order to calculate the second grinding rigidity, which is the grinding rigidity in the second grinding step, using the second actual cutting amount and the second normal resistance force,
A control device for controlling the grinding wheel cutting device, the workpiece diameter measuring device, the normal force measuring means, the grinding rigidity calculating means, and the retraction amount calculating means;
A grinding machine comprising

Images