JP2011093017A - Grinding machine and grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding machine and method more accurately grinding utilizing a reverse grinding. <P>SOLUTION: A reverse grinding is performed after a first forward grinding. During the reverse grinding, target grinding resistances Fe (&theta;) in respective rotational phases &theta; are generated based on residual grinding amounts E(&theta;) of a cylindrical workpiece W within the respective rotational phases of the cylindrical workpiece W from the present rotational phase &theta;t to the target rotational phase &theta;e. Then, the reverse grinding is performed while controlling so that grinding resistances Ft detected by a force sensor 50 match the target grinding resistances Fe (&theta;). <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a grinding machine and a grinding method for grinding an outer periphery or an inner periphery of a cylindrical workpiece.

  Conventionally, as grinding machines for grinding the outer periphery or inner periphery of a cylindrical workpiece, there are those described in JP-A-7-214466 (Patent Document 1) and JP-A-8-168957 (Patent Document 2). Patent Documents 1 and 2 describe performing backward grinding. The backward grinding is a grinding process that is performed while moving the grinding wheel in a direction of separating from the cylindrical workpiece after the forward grinding performed by moving the grinding wheel in a direction in which the grinding wheel is pressed against the cylindrical workpiece. In forward grinding, since the grinding wheel is pressed against the cylindrical workpiece, the cylindrical workpiece is bent. Further, in forward grinding, the remaining grinding amount E (θ) varies depending on the rotational phase θ of the cylindrical workpiece. In the backward grinding, the remaining grinding portion in the forward grinding is ground while reducing the amount of deflection of the cylindrical workpiece generated in the forward grinding. Thus, by performing the backward grinding, it is possible to greatly reduce the grinding time as compared with the grinding work that is entirely performed by forward grinding.

JP-A-7-214466 JP-A-8-168957

  An object of the present invention is to provide a grinding machine and a grinding method capable of performing grinding with higher accuracy by using the backward grinding described in Patent Documents 1 and 2.

In order to solve the above problem, the invention of a grinding machine according to claim 1 is:
A grinding machine for grinding the outer periphery or inner periphery of a cylindrical workpiece,
With a grinding wheel,
A workpiece support means for rotatably supporting and driving the cylindrical workpiece;
Moving means for relatively moving the cylindrical workpiece and the grinding wheel so that the cylindrical workpiece and the grinding wheel approach or separate from each other;
Grinding resistance detection means for detecting a grinding resistance Ft generated by grinding the cylindrical workpiece by the grinding wheel;
First forward grinding control means for performing first forward grinding to increase the amount of deflection ω of the cylindrical workpiece by relatively moving the grinding wheel in a direction in which the grinding wheel is pressed against the cylindrical workpiece;
After the first forward grinding, during the backward grinding performed while the grinding wheel is relatively moved in a direction away from the cylindrical workpiece to reduce the amount of deflection ω of the cylindrical workpiece, the cylindrical workpiece Between the current rotational phase θt and the target rotational phase θe until the target rotational phase θe reaches the target rotational phase θe, based on the residual grinding amount E (θ) of the cylindrical workpiece at each rotational phase θ. target grinding resistance generating means for generating θ),
Reverse grinding control means for performing the backward grinding by controlling the grinding resistance Ft detected by the grinding resistance detection means to coincide with the target grinding resistance Fe (θ);
It is to provide.

The invention according to claim 2 is the invention according to claim 1,
The grinding resistance detection means is a force sensor provided in the workpiece support means.
The invention according to claim 3 is the invention according to claim 1,
The grinding resistance detecting means is a torque detecting means for detecting a driving torque for rotationally driving the cylindrical work by the work supporting means.

The invention according to claim 4 is any one of claims 1 to 3,
The first forward grinding control means performs the first forward grinding to a finishing diameter Df in at least a part of the cylindrical workpiece,
The residual grinding amount E (θ) at each rotational phase θ is a residual grinding amount with respect to the finishing diameter Df.

The invention according to claim 5 is any one of claims 1 to 3,
The first forward grinding control means performs the first forward grinding to a finishing diameter Df in at least a part of the cylindrical workpiece,
The residual grinding amount E (θ) at each rotational phase θ is a residual grinding amount with respect to the finishing diameter Df.
It is further provided with a spark-out control means for performing a spark-out after setting the cutting amount of the grinding wheel with respect to the cylindrical workpiece to zero after the backward grinding.

The invention according to claim 6 is any one of claims 1 to 5,
The target grinding resistance generating means generates the target grinding resistance Fe (θ) so that the grinding resistance Ft becomes zero when the target rotational phase θe of the cylindrical workpiece is reached.
The invention according to claim 7 is any one of claims 1 to 5,
When the target grinding resistance generating means reaches the target rotational phase θe of the cylindrical workpiece, the grinding resistance Ft corresponds to a dynamic pressure effect due to the coolant liquid between the cylindrical workpiece and the grinding wheel. The target grinding resistance Fe (θ) is generated so as to be a value Fε1 to be performed.

The invention according to claim 8 is the invention according to claim 7,
The grinding machine
A sizing device for measuring the grinding diameter Dt of the cylindrical workpiece;
Estimation means for estimating a value Fε1 corresponding to the dynamic pressure effect, based on a reduction amount of the grinding diameter Dt of the cylindrical workpiece and the grinding resistance Ft detected by the grinding resistance detection means;
Further comprising
The target grinding resistance generation means generates the target grinding resistance Fe (θ) based on the estimated value Fε1 obtained by the estimation means.

The invention according to claim 9 is the invention according to claim 8,
The estimation means corresponds to the dynamic pressure effect based on the amount of decrease in the grinding diameter Dt of the cylindrical workpiece and the grinding resistance Ft in a transient state where the amount of deflection ω of the cylindrical workpiece is changing. The estimated value Fε1.

The invention according to claim 10 is any one of claims 1 to 3,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε1 from the finishing diameter Df in at least a part of the cylindrical workpiece,
The residual grinding amount E (θ) in each rotational phase θ is a residual grinding amount with respect to a state in which the remaining margin Rε1 is left from the finishing diameter Df.
It is further provided with a spark-out control means for grinding the remaining allowance Rε1 by spark-out after setting the cutting amount of the grinding wheel with respect to the cylindrical workpiece to zero after the backward grinding.

The invention according to claim 11 is the invention according to claim 10,
The target grinding resistance generating means is configured to provide the target grinding resistance Fe (θ) at each rotational phase θ so that the grinding resistance Ft becomes a predetermined value Fε2 when the target rotational phase θe of the cylindrical workpiece is reached. Is to generate

The invention according to claim 12 is any one of claims 1 to 11,
In the target grinding resistance generating means, the current rotation phase θt of the cylindrical workpiece to the target rotation phase θe is set to one rotation of the cylindrical workpiece.

The invention according to claim 13 is any one of claims 1 to 11,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε2 from the finishing diameter Df in at least a part of the cylindrical workpiece,
In the target grinding resistance generating means, the current rotation phase θt of the cylindrical workpiece to the target rotation phase θe are set for a plurality of rotations of the cylindrical workpiece.

The invention according to claim 14 is the invention according to claim 13,
A depth estimating means for estimating a depth of a work-affected layer generated in the first forward grinding;
The first forward grinding control means executes the first forward grinding by setting the remaining margin Rε2 to be equal to or greater than the work-affected layer depth.

The invention according to claim 15 is any one of claims 1 to 14,
Based on the grinding resistance Ft at each rotational phase θ measured at the time of the first forward grinding by the grinding resistance detection means, the grinding machine at each rotational phase θ at the end of the first forward grinding. A grinding residual amount estimating means for estimating a grinding residual amount E (θ) of the cylindrical workpiece;
The target grinding resistance generating means generates the target grinding resistance Fe (θ) based on the residual grinding amount E (θ) estimated by the residual grinding amount estimation means.

The invention according to claim 16 is the invention according to claim 15,
The remaining grinding amount estimation means is based on the grinding resistance Ft at each rotational phase θ and the grinding diameter Dt of the cylindrical workpiece at each rotational phase θ during the first forward grinding. It is to estimate the quantity E (θ).

The invention according to claim 17 is any one of claims 1 to 3,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε3 from the finishing diameter Df in at least a part of the cylindrical workpiece,
The grinder is the second forward after the backward grinding so that the grinding resistance Ft at each rotational phase θ becomes constant while moving the grinding wheel relative to the cylindrical workpiece. A grinding resistance constant forward grinding control means for performing grinding is further provided.

The invention according to claim 18 is the invention according to claim 17,
The grinder further includes spark-out control means for performing a spark-out after the second forward grinding, with the cutting amount of the grinding wheel with respect to the cylindrical workpiece set to zero.

The invention according to claim 19 is characterized in that, in claim 1,
The reverse grinding control means switches from the first forward grinding to the backward grinding when the grinding diameter Dt at a predetermined rotational phase θ of the cylindrical workpiece reaches a set value.

The invention of the grinding method according to claim 20 comprises:
With a grinding wheel,
A workpiece support means for rotatably supporting and driving a cylindrical workpiece;
Moving means for relatively moving the cylindrical workpiece and the grinding wheel so that the cylindrical workpiece and the grinding wheel approach or separate from each other;
Grinding resistance detection means for detecting a grinding resistance Ft generated by grinding the cylindrical workpiece by the grinding wheel;
A grinding method comprising grinding an outer periphery or an inner periphery of the cylindrical workpiece,
A first forward grinding step of performing a first forward grinding for relatively moving the grinding wheel in a direction in which the grinding wheel is pressed against the cylindrical workpiece to increase a deflection amount ω of the cylindrical workpiece;
After the first forward grinding, during the backward grinding performed while the grinding wheel is relatively moved in a direction away from the cylindrical workpiece to reduce the amount of deflection ω of the cylindrical workpiece, the cylindrical workpiece Between the current rotational phase θt and the target rotational phase θe until the target rotational phase θe reaches the target rotational phase θe, based on the residual grinding amount E (θ) of the cylindrical workpiece at each rotational phase θ. θ) to produce a target grinding resistance process;
A reverse grinding step of controlling the grinding resistance Ft detected by the grinding resistance detection means to match the target grinding resistance Fe (θ) and executing the backward grinding;
It is to provide.

  According to the first aspect of the invention configured as described above, in the backward grinding, the control is performed based on the grinding resistance Ft. Here, the grinding amount and the grinding resistance (resistance caused by grinding the cylindrical workpiece) are proportional. That is, if the remaining grinding amount E (θ) for each rotation phase θ can be grasped, the target grinding resistance Fe (θ) proportional to the remaining grinding amount E (θ) can be set. Therefore, in the backward grinding, feedback control by the grinding resistance Ft can be performed using the target grinding resistance Fe (θ) as a command value. Thereby, the processing precision of the cylindrical workpiece | work obtained by reverse grinding can be improved. The grinding resistance Ft may coincide with the grinding resistance, but may be a value obtained by adding a resistance component due to the influence of, for example, the dynamic pressure effect of the coolant to the grinding resistance. That is, the grinding resistance Ft includes at least the grinding resistance.

According to the invention which concerns on Claim 2, resistance Ft is reliably detectable by using the force sensor provided in the workpiece | work support means.
According to the invention which concerns on Claim 3, resistance Ft is reliably detectable by using the drive torque of a workpiece | work support means.
According to the invention which concerns on Claim 4, it can grind to the finishing diameter Df reliably in a short time.

  According to the invention which concerns on Claim 5, spark-out is performed. Here, in the present invention, the grinding is performed to the finishing diameter Df by the first forward grinding, and the residual grinding amount E (θ) with respect to the finishing diameter Df is ground in the backward grinding. That is, in the spark-out of the present invention, no grinding amount is theoretically generated. However, in the first forward grinding and the backward grinding, the grinding surface processing accuracy may vary for various reasons. Therefore, in the spark-out of the present invention, this variation can be made uniform, so that the surface property of the grinding surface of the cylindrical workpiece is very good.

  According to the sixth aspect of the invention, the target grinding resistance Fe (θ) is set such that the grinding resistance Ft becomes zero when the target rotational phase θe is reached. Therefore, the grinding resistance Ft becomes zero when the backward grinding is finished. Thereby, highly accurate processing can be reliably performed on the entire circumference of the cylindrical workpiece.

  According to the invention which concerns on Claim 7, the influence of the dynamic pressure by coolant liquid is considered, and the feedback control by grinding resistance can be performed reliably. Here, in the grinding process, a coolant liquid is generally used. When a cylindrical workpiece is ground by the grinding wheel, the resistance generated in the cylindrical workpiece is larger than the grinding resistance due to the resistance component generated by the influence of the dynamic pressure by the coolant liquid. Furthermore, even if the grinding wheel and the cylindrical workpiece are not in contact with each other, if the separation distance is very small, resistance may be generated in the cylindrical workpiece due to the influence of the dynamic pressure by the coolant liquid. . That is, since the resistance component generated by the influence of the dynamic pressure of the coolant fluid causes the cylindrical workpiece to bend, even if the grinding resistance Ft becomes zero, there is a possibility that residual grinding may occur. Therefore, as in the present invention, when the target rotational phase θe is reached, by setting the target grinding resistance Fe (θ) so that the grinding resistance Ft becomes the value Fε1 corresponding to the dynamic pressure effect, it is ensured. In addition, the influence of the dynamic pressure due to the coolant liquid is eliminated, and high-precision grinding can be performed.

  According to the eighth aspect of the invention, the value Fε1 corresponding to the dynamic pressure effect can be reliably estimated by utilizing the fact that the relationship between the reduction amount of the grinding diameter and the grinding resistance is a linear relationship. That is, highly accurate grinding can be reliably performed.

  According to the ninth aspect of the present invention, the value Fε1 corresponding to the amount of the dynamic pressure effect of the coolant is estimated based on the information in the transitional state of forward grinding immediately before the backward grinding is performed. By utilizing the information in this transient state, the value Fε1 corresponding to the dynamic pressure effect of the coolant can be reliably estimated. Here, the value Fε1 corresponding to the dynamic pressure effect of the coolant may change depending on, for example, the sharpness of the grinding wheel. Therefore, as in the present invention, by using the information in the transitional state of the immediately preceding forward grinding, the value Fε1 corresponding to the dynamic pressure effect of the coolant fluid in the current backward grinding can be reliably estimated.

  Here, the transitional state means that when the grinding wheel shifts from the state where the grinding wheel is separated from the cylindrical workpiece (Kanken) to the state where the grinding wheel is pressed against the cylindrical workpiece (grinding), the amount of deflection of the cylindrical workpiece gradually increases. There is a state that grows. At this time, since the cylindrical workpiece is bent, the amount of grinding is smaller than the relative movement amount of the grinding wheel. And until the time change of the grinding amount of the cylindrical workpiece coincides with the time change of the relative movement amount of the grinding wheel, the time change of the relative movement amount of the grinding wheel and the time change of the outer diameter of the cylindrical workpiece are different. It becomes. This state is called a transient state. That is, in a transient state, the relative movement amount of the grinding wheel and the outer diameter of the cylindrical workpiece are in a non-linear relationship. Further, there is a steady state with respect to the transient state. The steady state is a state where the time change of the relative movement amount of the grinding wheel and the time change of the outer diameter of the cylindrical workpiece are the same. That is, in a steady state, the amount of bending of the cylindrical workpiece is constant. In a steady state, the relative movement amount of the grinding wheel and the outer diameter of the cylindrical workpiece have a linear relationship.

  According to the tenth aspect of the present invention, the remaining margin is set to Rε1 when the target rotational phase θe is reached. Accordingly, when the backward grinding is finished, the remaining margin becomes the predetermined value Rε1. Since the remaining predetermined value Rε1 can be ground by spark-out, a highly accurate shape can be obtained after the spark-out is completed.

  As described above, it is known that the grinding amount and the grinding resistance are proportional. Therefore, according to the eleventh aspect of the invention, the target grinding resistance Fe (θ) is set so that the remaining allowance corresponding to the grinding resistance Ft becomes the remaining allowance Rε2 when the backward grinding is finished. Thus, the remaining margin Rε1 can be reliably ground by spark-out.

  According to the twelfth aspect of the present invention, the backward grinding can be completed in the shortest time. Thereby, the whole grinding time can be significantly shortened.

  According to the invention of claim 13, the backward grinding is performed by a plurality of rotations. In other words, the greater the number of times of reverse grinding, the more like the finish grinding. While performing reverse grinding, reverse grinding corresponding to rough grinding, reverse grinding corresponding to fine grinding, reverse grinding corresponding to fine grinding, and the like can be performed. As a result, it is possible to perform extremely accurate grinding.

  According to the fourteenth aspect of the present invention, the work-affected layer generated in the forward grinding can be reliably removed in the backward grinding. Therefore, a work-affected layer is not generated on the cylindrical workpiece that has finished the reverse grinding.

  Here, at the time when the first forward grinding is finished, it is theoretically considered that the remaining grinding amount E (θ) for one round of the cylindrical workpiece from the current rotational phase θt is linear. However, in an actual grinding process, the above-mentioned remaining grinding amount E (θ) may become non-linear due to changes in the mechanical rigidity of the grinding machine and the sharpness of the grinding wheel.

  Therefore, according to the fifteenth aspect of the present invention, when the first forward grinding is finished, the remaining grinding with respect to the rotational phase θ from the current rotational phase θt of the cylindrical workpiece to the target rotational phase θe is reached. Even when the amount E (θ) is non-linear, the target grinding resistance Fe (θ) in the reverse grinding can be set according to the remaining grinding amount E (θ). That is, the grinding residue in the first forward grinding can be reliably ground in the backward grinding. Therefore, the grinding accuracy can be improved.

According to the invention which concerns on Claim 16, the estimated value of the grinding residual amount E ((theta)) in each rotation phase (theta) can be obtained more reliably.
According to the seventeenth aspect of the present invention, the second forward grinding is performed after the backward grinding so that the grinding resistance Ft becomes constant. Thereby, even if a variation occurs in the backward grinding, the variation can be reliably removed by the second forward grinding. Therefore, highly accurate grinding can be realized.

  Here, the second forward grinding is forward grinding such that the grinding resistance is constant. Therefore, theoretically, it is considered that a step is generated between the portion where the second forward grinding is finished and the rotational phase located slightly ahead of the portion in the cylindrical workpiece. Therefore, according to the eighteenth aspect, the step can be removed by sparking out. That is, even if a step is generated by the second forward grinding, the final ground surface can be made highly accurate by sparking out.

  According to the nineteenth aspect of the invention, the switching point between the first forward grinding and the backward grinding is determined using the grinding diameter Dt of the cylindrical workpiece. Thereby, it is possible to switch from the first forward grinding to the backward grinding at an appropriate position.

  According to the invention of the grinding method of the twentieth aspect, the same effect as that of the invention related to the grinding machine described above can be obtained. In addition, in the invention of the grinding method, the other features in the invention of the grinding machine described above can be applied in the same manner, and the same effect can be obtained.

1st embodiment: It is a top view of a grinding machine. It is a flowchart of a grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time. It is a control block diagram in reverse grinding. It is a figure which shows the position of the workpiece | work and grinding wheel in each of the time t2-t5 of FIG. (A) shows the state at time t2 in FIG. 3, (b) shows the state at time t3 in FIG. 3, (c) shows the state at time t4 in FIG. 3, and (d) shows the time at FIG. The state at t5 is shown. 5A is an enlarged view of the state of FIG. 5C, and FIG. 5B is a diagram showing the relationship between the remaining grinding amount E (θ) and the target grinding resistance Fe (θ) with respect to the rotational phase θ of the workpiece. . It is a flowchart of a modification of a first embodiment: grinding method. 2nd embodiment: It is a flowchart of the grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time. 3rd embodiment: It is a flowchart of the grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time. It is a graph used when estimating dynamic pressure effect equivalent value F (epsilon) 1, Comprising: The relationship of the grinding resistance Ft with respect to the outer diameter reduction amount of a workpiece | work is shown. It is a figure which shows the relationship between the grinding residual amount E ((theta)) and target grinding resistance Fe ((theta)) with respect to rotation phase (theta) of a workpiece | work. 4th embodiment: It is a flowchart of the grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time. It is a figure which shows the relationship between the grinding residual amount E ((theta)) and target grinding resistance Fe ((theta)) with respect to rotation phase (theta) of a workpiece | work. 5th embodiment: It is a graph which shows the position of the grindstone stand, the workpiece outer diameter Dt, the grinding resistance Ft, and the deflection amount ω with respect to the elapsed time. It is a figure which shows the relationship between the grinding residual amount E ((theta)) and target grinding resistance Fe ((theta)) with respect to rotation phase (theta) of a workpiece | work. It is a figure which shows the position of the workpiece | work and a grinding wheel in each of the time t4-t6 of FIG. (A) shows the state at time t4 in FIG. 17, (b) shows the state at time t5 in FIG. 17, and (c) shows the state at time t6 in FIG. Sixth embodiment: (a) shows the time change of the target grinding resistance Fe (θ) when it has a steady state, and (b) shows the time change of the target grinding resistance Fe (θ) when it does not have a steady state. Show. It is a flowchart of a grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time. It is a figure which shows the relationship between the grinding residual amount E ((theta)) and target grinding resistance Fe ((theta)) with respect to rotation phase (theta) of a workpiece | work. 7th embodiment: It is a flowchart of the grinding method. It is a graph which shows the position of a grindstone stand, workpiece outer diameter Dt, grinding resistance Ft, and amount of deflection ω with respect to elapsed time.

<First embodiment>
The grinding machine of 1st embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the first embodiment is a method in which the first forward grinding is executed and subsequently the backward grinding is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe.

(Configuration of grinding machine)
A grinding wheel traverse type cylindrical grinder will be described as an example of the grinder of this embodiment. The workpiece W to be processed by the grinding machine is a cylindrical workpiece such as a camshaft or a crankshaft. However, the workpiece W can be applied to a camshaft or a crankshaft as long as it is cylindrical. The term “cylindrical” as used herein refers to the case where the outer peripheral surface shape of the cross section in the direction perpendicular to the axis is circular, the inner peripheral surface shape of the cross section in the direction perpendicular to the axis is circular, Including meaning. That is, the cylindrical workpiece W includes a columnar workpiece.

  The grinding machine will be described with reference to FIG. As shown in FIG. 1, the grinding machine 1 includes a bed 10, a headstock 20, a tailstock 30, a grindstone support device 40, a force sensor 50, a sizing device 60, and a control device 70. Is done.

  The bed 10 has a substantially rectangular shape and is disposed on the floor. However, the shape of the bed 10 is not limited to a rectangular shape. On the upper surface of the bed 10, a pair of grinding wheel table guide rails 11 a and 11 b are formed in parallel to each other so as to extend in the left-right direction (Z-axis direction) in FIG. 1. The pair of grinding wheel head guide rails 11 a and 11 b are rails on which the grinding wheel base traverse base 41 constituting the grinding wheel support device 40 can slide. Further, the bed 10 is provided with a wheel head Z-axis ball screw 11c for driving the wheel head traverse base 41 in the left-right direction in FIG. 1 between the pair of wheel head guide rails 11a and 11b. A grinding wheel base Z-axis motor 11d for rotating the grinding wheel base Z-axis ball screw 11c is disposed.

  The headstock 20 (corresponding to the “work support means” of the present invention) includes a headstock body 21, a main shaft 22, a main shaft motor 23, and a main shaft center 24. The headstock main body 21 is fixed to the lower left side of FIG. However, the headstock body 21 can slightly adjust the position in the Z-axis direction with respect to the bed 10. Inside the headstock main body 21, a main shaft 22 is inserted and supported so as to be rotatable about the axis (around the Z axis in FIG. 1). A spindle motor 23 is provided at the left end of the spindle 22 in FIG. 1, and the spindle 22 is rotationally driven by the spindle motor 23 with respect to the spindle head body 21. The main shaft motor 23 has an encoder, and the rotation angle of the main shaft motor 23 can be detected by the encoder. A spindle center 24 that supports one axial end of the shaft-like workpiece W is attached to the right end of the spindle 22.

  The tailstock 30 (corresponding to the “work support means” of the present invention) includes a tailstock body 31 and a tailstock center 32. The tailstock body 31 is fixed to the lower right side of FIG. However, the tailstock body 31 can slightly adjust the position in the Z-axis direction with respect to the bed 10. The tailstock 31 is provided with a tailstock center 32 that cannot rotate with respect to the tailstock 31. The rotating shaft of the tailstock center 32 is located coaxially with the rotating shaft of the main shaft 22.

  The tailstock center 32 supports the other end of the workpiece W in the axial direction. That is, the tailstock center 32 is disposed so as to face the spindle center 24. The both ends of the workpiece W are rotatably supported by the spindle center 24 and the tailstock center 32. Further, the tailstock center 32 can change the amount of protrusion from the left end surface of the tailstock body 31. That is, the protrusion amount of the tailstock center 32 can be adjusted according to the position of the workpiece W. In this way, the workpiece W is held by the spindle center 24 and the tailstock center 32 so as to be rotatable around the spindle axis (around the Z axis).

  The grinding wheel support device 40 includes a grinding wheel base traverse base 41, a grinding wheel base 42, a grinding wheel 43, and a grinding wheel rotation motor 44. The grinding wheel base traverse base 41 is formed in a rectangular flat plate shape, and is slidably disposed on the pair of grinding wheel base guide rails 11 a and 11 b in the upper surface of the bed 10. The grinding wheel base traverse base 41 is connected to a nut member of the grinding wheel base Z-axis ball screw 11c, and moves along the pair of grinding wheel base guide rails 11a and 11b by driving the grinding wheel base Z-axis motor 11d. This wheel head Z-axis motor 11d has an encoder, and the encoder can detect the rotation angle of the wheel head Z-axis motor 11d.

  A pair of X-axis guide rails 41a and 41b on which the grinding wheel base 42 can slide are extended on the upper surface of the grinding wheel base traverse base 41 so as to extend in the vertical direction (X-axis direction) in FIG. Is formed. Further, the grinding wheel base traverse base 41 is provided with an X axis ball screw 41c for driving the grinding wheel base 42 in the vertical direction of FIG. 1 between the pair of X axis guide rails 41a and 41b. An X-axis motor 41d that rotationally drives the ball screw 41c is disposed. The X-axis motor 41d has an encoder, and the encoder can detect the rotation angle of the X-axis motor 41d.

  The grinding wheel base 42 is slidably disposed on the pair of X-axis guide rails 41 a and 41 b in the upper surface of the grinding wheel base traverse base 41. The grinding wheel base 42 is connected to a nut member of the X-axis ball screw 41c, and moves along the pair of X-axis guide rails 41a and 41b by driving the X-axis motor 41d. That is, the grindstone table 42 can move relative to the bed 10, the spindle stock 20 and the tailstock 30 in the X-axis direction (plunge feed direction) and the Z-axis direction (traverse feed direction).

  A hole penetrating in the left-right direction in FIG. 1 is formed in the lower portion of FIG. A grinding wheel rotating shaft member (not shown) is supported in the through hole of the grinding wheel base 42 so as to be rotatable around the grinding wheel central axis (around the Z axis). A disc-shaped grinding wheel 43 is coaxially attached to one end (left end in FIG. 1) of the grinding wheel rotating shaft member. That is, the grinding wheel 43 is cantilevered with respect to the grinding wheel base 42. Specifically, the right end side of the grinding wheel 43 in FIG. 1 is supported by the grinding wheel base 42, and the left end side of the grinding wheel 43 in FIG. 1 is a free end. The rotating shaft of the grinding wheel 43 is provided in parallel to the rotating shaft of the main shaft 22. A grinding wheel rotating motor 44 is fixed on the upper surface of the grinding wheel base 42. A pulley is suspended between the other end of the grinding wheel rotating shaft member (the right end in FIG. 1) and the rotating shaft of the grinding wheel rotating motor 44, so that the grinding wheel 43 is driven by the driving of the grinding wheel rotating motor 44. Rotate around.

The force sensor 50 (corresponding to the “grinding resistance detecting means” of the present invention) is provided on the main shaft 22 and measures the force of the X-axis direction component (normal component at the grinding point) applied to the main shaft 22. That is, the force sensor 50 detects the normal-direction grinding resistance Ft generated when the workpiece W is ground (pressed) by the grinding wheel 43. Here, since the grinding wheel 43 is processed while being moved only in the X direction with respect to the workpiece W, the force sensor 50 only measures the force of the X-axis direction component. A signal measured by the force sensor 50 is output to the control device 70.
The sizing device 60 measures the outer diameter (corresponding to the “grinding diameter” of the present invention) Dt of the workpiece W at the machining position. The outer diameter Dt of the workpiece W measured by the sizing device 60 is output to the control device 70.

  The control device 70 (corresponding to each “control means” and “estimation means” of the present invention) controls each motor, rotates the workpiece W around the main axis, rotates the grinding wheel 43, and rotates the workpiece W. The outer peripheral surface of the workpiece W is ground by changing the relative positions of the grinding wheel 43 in the Z-axis direction and the X-axis direction. The control device 70 may perform position control based on each position detected by each encoder, or may perform resistance control based on the machining resistance detected by the force sensor 50. Details will be described later.

(Description of grinding method)
Next, the grinding method in 1st embodiment is demonstrated with reference to FIGS. As shown in FIG. 2, first, the first forward grinding is started (S1). Here, the first forward grinding corresponds to the time t1 to t4 in FIG. That is, as shown in FIGS. 3A and 3B and FIGS. 5A and 5B, in the first forward grinding, the grinding wheel 43 is relatively moved in the direction in which the grinding wheel 43 is pressed against the workpiece W, and the deflection amount ω of the workpiece W is set. This is an increase in grinding. Specifically, as shown by the position of the grindstone table 42 in FIG. 3, the grindstone table 42 is moved at a constant speed in the X-axis direction and in the direction of pressing against the workpiece W.

  At time t1 in FIG. 3, the grinding wheel 43 has not yet contacted the workpiece W. When the grinding wheel base 42 is moved in the direction toward the workpiece W, as shown in FIG. 3A, the position of the grinding wheel base 42 in FIG. 3 and the outer diameter Dt of the workpiece W at the time t2 in FIG. The vehicle 43 contacts the work W. At this time, the center of rotation of the workpiece W coincides with the center of the main axis.

  Subsequently, during the period from time t2 to time t3 in FIG. 3, the grinding resistance Ft detected by the force sensor 50 increases rapidly. At the same time, the deflection amount ω of the workpiece W also increases. The deflection amount ω of the workpiece W corresponds to the difference between the outer diameter Dt of the workpiece W detected by the sizing device 60 and the position of the grindstone table 42 in FIG. 3. Here, as shown by the deflection amount ω of the workpiece W and the grinding resistance Ft in FIG. 3, the grinding resistance Ft and the deflection amount ω of the workpiece W have a proportional relationship. Therefore, at the time t3 in FIG. 3, as shown in FIG. 5B, the rotation center of the workpiece W at the machining position is located at a position shifted from the center of the main shaft by the deflection amount ωmax. Here, in the first forward grinding, the state in which the grinding resistance Ft changes, that is, the period from time t2 to t3 in FIG. 3 is referred to as a transient state.

  Subsequently, the grinding resistance Ft detected by the force sensor 50 is constant from time t3 to time t4 in FIG. At the same time, the deflection amount ω of the workpiece W is also constant. Here, the deflection amount ω of the workpiece W corresponds to the difference between the outer diameter Dt of the workpiece W detected by the sizing device 60 and the position of the grindstone table 42 in FIG. 3. That is, during the period from time t3 to t4 in FIG. 3, the grinding resistance Ft and the position of the grindstone base 42 are parallel. During this period, as shown in FIGS. 5B and 5C, the rotation center of the workpiece W at the machining position is located at a position shifted by the deflection amount ωmax from the spindle center. Here, in the first forward grinding, a state in which the grinding resistance Ft is constant, that is, a period from time t3 to time t4 in FIG. 3 is referred to as a steady state.

  Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W has reached a preset outer diameter Dth (S2). If the outer diameter Dt of the workpiece W has not yet reached the set value Dth (S2: N), the first forward grinding is continued. On the other hand, when the outer diameter Dt of the workpiece W reaches the set value Dth (S2: Y), the first forward grinding is finished (S3).

  Subsequently, reverse grinding is started (S4). That is, when the outer diameter Dt of the workpiece W reaches the set value Dth, the first forward grinding is switched to the backward grinding. Here, the reverse grinding is grinding performed while the grinding wheel 43 is relatively moved in the direction away from the workpiece W to reduce the deflection amount ω of the workpiece W.

  This backward grinding will be described in detail with reference to FIGS. 6 (a) and 6 (b). FIG. 6A shows the workpiece W and the grinding wheel 43 in a state where the first forward grinding has been completed. As shown in FIG. 6A, it can be seen that the workpiece W has a different grinding residual amount E (θ) with respect to the finishing diameter Df in accordance with the rotational phase θ. Specifically, as shown in FIGS. 6A and 6B, when the rotational phase θ of the workpiece W is 0 deg (corresponding to the “current rotational phase θt” of the present invention), the grinding residual amount is E (0 ) The target grinding resistance at this time is set to Fe (0). When the rotational phase θ of the workpiece W is π / 2 deg, the remaining grinding amount is [3/4 × E (0)], so the target grinding resistance is set to [3/4 × Fe (0)]. .

  When the rotational phase θ of the workpiece W is πdeg, the remaining grinding amount is [1/2 × E (0)], so the target grinding resistance is set to [1/2 × Fe (0)]. When the rotational phase θ of the workpiece W is 3π / 4 deg, the remaining grinding amount is [1/4 × E (0)], so the target grinding resistance is set to [1/4 × Fe (0)]. When the rotational phase θ of the workpiece W is 2πdeg (corresponding to the “target rotational phase θe” of the present invention), the remaining grinding amount is zero, so the target grinding resistance Fe (θe) is also set to zero. However, in the present embodiment, it is assumed that the remaining grinding amount E (θ) has a linear relationship with the rotational phase θ of the workpiece W when the first forward grinding is finished.

  As shown in FIGS. 6A and 6B, the backward grinding in the present embodiment is performed only while the workpiece W is rotated once. In other words, as shown in FIG. 3, the workpiece W makes one rotation from the start time t4 to the end time t5 of the reverse grinding. The grinding resistance Ft at the end time t5 of the reverse grinding is set to zero. The fact that the grinding resistance Ft becomes zero at time t5 means that the center of rotation of the workpiece W coincides with the center of the spindle, as shown in FIG. 5 (d).

  Here, the control operation in the reverse grinding will be described with reference to the control block diagram shown in FIG. As shown in FIG. 4, in the backward grinding, feedback control based on the grinding resistance Ft is performed. Specifically, the target grinding resistance generation unit 101 sets the remaining grinding amount E (θ) of the workpiece W at each rotation phase θ from the current rotation phase θt of the workpiece W to the target rotation phase θe. Based on this, a target grinding resistance Fe (θ) at each rotational phase θ is generated. In this embodiment, the target grinding resistance Fe (θ) is linear as shown in FIG. 6B and the grinding resistance Ft at time t4 to t5 in FIG. 3 and is zero at time t5. It is set to become.

  The grinding resistance detector 102 corresponds to the force sensor 50 and detects the grinding resistance Ft. The adder 103 adds the grinding resistance Ft detected by the grinding resistance detector 102 to the target grinding resistance Fe (θ) generated by the target grinding resistance generator 101. Then, based on the resistance calculated by the adder 103, the wheel head trajectory generator 104 generates a trajectory of the wheel head 42 in the X-axis direction. Then, the X-axis motor 105 (corresponding to 41d in FIG. 1) is driven based on the generated orbit in the X-axis direction of the grindstone table 42. Thus, in the reverse grinding, feedback control is performed so that the grinding resistance Ft matches the target grinding resistance Fe (θ).

  Subsequently, returning to FIG. In the above description, it has been described up to the start of backward grinding in S4 of FIG. Subsequently, it is determined whether or not the grinding resistance Ft has reached zero (S5). If the grinding resistance Ft has not yet reached zero (S5: N), the backward grinding is continued. On the other hand, when the grinding resistance Ft reaches zero (S5: Y), the reverse grinding is finished (S6), and the processing of the grinding method is finished. That is, it can be seen that the outer diameter Dt of the workpiece W reaches the finishing diameter Df at t5 in FIG.

  According to this embodiment, the grinding time can be significantly shortened. In particular, the first forward grinding can be performed as roughing, and the backward grinding can be performed as finishing. In the backward grinding, as described above, high-precision grinding is possible by using the grinding resistance.

<Modification of First Embodiment>
In the first embodiment, as shown in S5 of FIG. 2, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached zero. In addition, as shown in FIG. 7, when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df, the backward grinding may be terminated. That is, in S5-1 of FIG. 7, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W reaches the finishing diameter Df. If this occurs (S5-1: Y), the reverse grinding is terminated. 7 is the same as FIG. 2 except for FIG. 5A, and a description thereof will be omitted.

<Second embodiment>
The grinding method of 2nd embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the second embodiment is a method in which the first forward grinding is executed, the backward grinding is subsequently executed, and then the spark-out is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. In the spark-out, the allowance is zero.

  In FIG. 8, steps S1 to S6 in the flowchart of FIG. 2 showing the grinding method of the first embodiment are common. Then, when the backward grinding is finished in step S6, spark out is executed (S7). Sparking is performed with the grinding wheel 43 in a state where the cutting amount for the workpiece W is zero. This spark-out is performed for the number of rotations of the workpiece W set in advance. Therefore, it is determined whether or not the workpiece W has been rotated a set number of times (S8). If the workpiece has been rotated the set number of times, the spark-out is terminated (S9).

  The position of the wheel head, the workpiece outer diameter Dt, the grinding resistance Ft, and the deflection amount ω with respect to the elapsed time at this time are as shown in FIG. That is, spark out is executed from time t5 to time t6. In addition, from time t1 to time t5 is common with 1st embodiment.

  In the first forward grinding and the backward grinding, there are cases where variations occur in the processing accuracy of the ground surface due to various reasons. By performing the spark-out in this embodiment, these variations can be made uniform. Therefore, the surface property of the grinding surface of the cylindrical workpiece W is very good.

<First Modification of Second Embodiment>
In the second embodiment, as shown in S5 of FIG. 8, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached zero. Alternatively, the reverse grinding may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S5 of FIG. 8, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S5: Y), the reverse grinding is finished. Then, a spark out is executed. In this case, substantially the same effect as the second embodiment is achieved.

<Second Modification of Second Embodiment>
In the second embodiment, as shown in S8 of FIG. 8, the end of the spark-out is determined based on whether or not the set number of times has been rotated. Instead, the spark-out may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S8 of FIG. 8, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S8: Y), the spark-out is terminated. This is applied when the end of the reverse grinding is determined based on whether or not the grinding resistance Ft has reached zero.

<Third embodiment>
The grinding method of 3rd embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the third embodiment is a method in which the first forward grinding is executed, the backward grinding is subsequently executed, and then the spark-out is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. Then, the end point of the backward grinding is set to the time when the grinding resistance Ft reaches a resistance component Fε1 (hereinafter referred to as “dynamic pressure effect equivalent value”) generated by the influence of the dynamic pressure of the coolant. Furthermore, in the spark-out, the dynamic pressure effect equivalent value Fε1 is taken into consideration.

  As shown in FIG. 10, the first forward grinding is started (S11). Here, the first forward grinding corresponds to the time t1 to t4 in FIG. Since it is the same as 1st embodiment during this period, detailed description is abbreviate | omitted.

  Subsequently, a large number of outer diameters Dt and grinding resistances Ft of the workpiece W in a transient state (time t2 to t3) are stored (S12). Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W has reached a preset outer diameter Dth (S13). If the outer diameter Dt of the workpiece W has not yet reached the set value Dth (S13: N), the first forward grinding is continued. On the other hand, when the outer diameter Dt of the workpiece W reaches the set value Dth (S13: Y), the first forward grinding is finished (S14).

  Subsequently, based on the outer diameter Dt and the grinding resistance Ft of the workpiece W in the transient state stored in step S12, a value Fε1 corresponding to the dynamic pressure effect due to the coolant liquid is estimated (S15). Here, FIG. 12 shows the relationship between the reduction amount of the outer diameter Dt of the workpiece W and the grinding resistance Ft in the transient state. If the stored many points are approximated by a straight line, they can be represented as a straight line shown in FIG. Then, the point at which the amount of decrease in the outer diameter Dt of the workpiece W becomes zero in the approximate straight line is estimated as the dynamic pressure effect equivalent value Fε1 due to the coolant.

  Subsequently, reverse grinding is started (S16). That is, when the outer diameter Dt of the workpiece W reaches the set value Dth, the first forward grinding is switched to the backward grinding. Subsequently, it is determined whether or not the grinding resistance Ft has reached the dynamic pressure effect equivalent value Fε1 (S17). If the grinding resistance Ft does not reach the dynamic pressure effect equivalent value Fε1 (S17: N), the reverse grinding is continued. On the other hand, when the grinding resistance Ft reaches the dynamic pressure effect equivalent value Fε1 (S17: Y), the reverse grinding is finished (S18). That is, the target grinding resistance Fe (θ) is set so that the grinding resistance Ft becomes the dynamic pressure effect equivalent value Fε1 at the end of the backward grinding (when the target rotational phase θe is reached).

  When the reverse grinding is finished, a spark out is executed (S19). This spark-out is performed with the grinding wheel 43 in a state where the cutting amount with respect to the workpiece W is zero. That is, at the spark-out, the position of the grindstone table 42 is shifted from the finishing diameter Df by a dimension corresponding to the dynamic pressure effect equivalent value Fε1. Then, this spark-out is performed for the number of rotations of the workpiece W set in advance. Therefore, it is determined whether or not the workpiece W has been rotated a set number of times (S20). If the workpiece has been rotated the set number of times, the spark-out is terminated (S21).

  Here, the backward grinding of the present embodiment will be described in detail with reference to FIG. As shown in FIG. 13, when the rotational phase θ of the workpiece W is 0 deg (corresponding to the “current rotational phase θt” of the present invention), the remaining grinding amount is E (0). The target grinding resistance at this time is set to Fe (0). When the rotational phase θ of the workpiece W is 2πdeg (corresponding to the “target rotational phase θe” of the present invention), the target grinding resistance Fe (θe) is set to be a dynamic pressure effect equivalent value Fε1. The remaining grinding amount at this time is E (θe). When the rotational phase θ of the workpiece W is πdeg, the remaining grinding amount is [1/2 × (E (0) + E (θe))], and the target grinding resistance is [1/2 × (Fe (0) + Fe). (Θe))].

  According to this embodiment, it is possible to reliably perform feedback control by grinding resistance in consideration of the influence of dynamic pressure due to the coolant liquid. Here, when the workpiece W is ground by the grinding wheel 43, the resistance generated in the workpiece W is larger than the grinding resistance due to the resistance component generated by the influence of the dynamic pressure by the coolant. Furthermore, even if the grinding wheel 43 and the workpiece W are not in contact with each other, if the separation distance is very small, the workpiece W may be resisted by the influence of the dynamic pressure due to the coolant liquid. In other words, since the work W is bent due to the resistance component caused by the influence of the dynamic pressure of the coolant, there is a possibility that a grinding residue may occur even if the grinding resistance Ft becomes zero. Therefore, by setting the target grinding resistance Fe (θ) so that the grinding resistance Ft becomes the dynamic pressure effect equivalent value Fε1 when the target rotational phase θe is reached (at the end of the backward grinding), it is ensured. High-precision grinding can be performed by eliminating the influence of dynamic pressure due to the coolant.

<First Modification of Third Embodiment>
In the third embodiment, as shown in S17 of FIG. 10, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached the dynamic pressure effect equivalent value Fε1. In addition, when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df, the reverse grinding may be terminated. That is, in S17 of FIG. 10, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S17: Y), the backward grinding is finished.

<Second Modification of Third Embodiment>
In the third embodiment, as shown in S20 of FIG. 10, the end of the spark-out is determined based on whether or not the set number of times has been rotated. Instead, the spark-out may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S20 of FIG. 10, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S20: Y), the spark-out is terminated. This is applied when the end of the reverse grinding is determined based on whether or not the grinding resistance Ft has reached the dynamic pressure equivalent value Fε1.

<Fourth embodiment>
The grinding method of 4th embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the fourth embodiment is a method in which the first forward grinding is executed, the backward grinding is subsequently executed, and then the spark-out is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. Then, at the end of the first forward grinding and the end of the backward grinding, the machining allowance Rε1 is left over the entire circumference of the workpiece W. That is, the machining allowance Rε1 is ground at the spark-out.

  As shown in FIG. 14, the first forward grinding is started (S31). Here, the first forward grinding corresponds to the time t1 to t4 in FIG. Since it is the same as 1st embodiment during this period, detailed description is abbreviate | omitted. Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W has reached a preset outer diameter Dth (S32). Here, the set outer diameter Dth is represented by [Df−ωmax + Rε1]. That is, at the end of the first forward grinding (time t4 in FIG. 15), the machining allowance Rε1 remains over the entire circumference.

  If the outer diameter Dt of the workpiece W has not yet reached the set value Dth (S32: N), the first forward grinding is continued. On the other hand, when the outer diameter Dt of the workpiece W reaches the set value Dth (S32: Y), the first forward grinding is finished (S33).

  Subsequently, reverse grinding is started (S34). That is, when the outer diameter Dt of the workpiece W reaches the set value Dth, the first forward grinding is switched to the backward grinding. Subsequently, it is determined whether or not the grinding resistance Ft has reached the set value Fε2 (S35). Here, the set value Fε2 is the grinding resistance Ft in a state where the outer diameter Dt of the workpiece W becomes the set value Dth. That is, the target grinding resistance Fe (θ) is set so that the grinding resistance Ft becomes the set value Fε2 at the end of the backward grinding (when the target rotational phase θe is reached).

  If the grinding resistance Ft does not reach the set value Fε2 (S35: N), the reverse grinding is continued. On the other hand, when the grinding resistance Ft reaches the set value Fε2 (S35: Y), the reverse grinding is finished (S36). At this time, the outer diameter Dt of the workpiece W is Df1 (= Df−Rε1).

  Here, the backward grinding of the present embodiment will be described in detail with reference to FIG. As shown in FIG. 16, when the rotational phase θ of the workpiece W is 0 deg (corresponding to the “current rotational phase θt” of the present invention), the remaining grinding amount is E (0). The target grinding resistance at this time is set to Fe (0). When the rotational phase θ of the workpiece W is 2πdeg (corresponding to the “target rotational phase θe” of the present invention), the remaining grinding amount E (θe) is set to the machining allowance Rε1. The target grinding resistance Fe (θe) at this time is set to be Fε2 corresponding to the machining allowance Rε1. When the rotational phase θ of the workpiece W is πdeg, the remaining grinding amount is [1/2 × (E (0) + E (θe))], and the target grinding resistance is [1/2 × (Fe (0) + Fe). (Θe))].

  Returning to FIG. When the reverse grinding is finished, a spark out is executed (S37). This spark-out is performed with the grinding wheel 43 in a state where the cutting amount with respect to the workpiece W is zero. That is, the machining allowance Rε1 is ground at the spark-out. Then, this spark-out is performed for the number of rotations of the workpiece W set in advance. Therefore, it is determined whether or not the workpiece W has been rotated a set number of times (S38). If the workpiece has been rotated the set number of times, the spark-out is terminated (S39).

  According to the present embodiment, the remaining margin is set to Rε1 when the target rotational phase θe is reached. Accordingly, when the backward grinding is finished, the remaining margin becomes the predetermined value Rε1. Since the remaining predetermined value Rε1 can be ground by spark-out, a highly accurate shape can be obtained after the spark-out is completed.

<First Modification of Fourth Embodiment>
In the fourth embodiment, as shown in S35 of FIG. 14, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached the set value Fε2. In addition, when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the diameter Df1 (= Df−Rε1) leaving the machining allowance Rε1, the backward grinding may be terminated. . That is, in S35 of FIG. 14, it is determined whether or not the outer diameter Dt of the work W detected by the sizing device 60 has reached the set diameter Df1, and the outer diameter Dt of the work W has reached the set diameter Df1. (S35: Y), the backward grinding is finished. Then, a spark out is executed. In this case, substantially the same effect as the second embodiment is achieved.

<Second Modification of Fourth Embodiment>
In the fourth embodiment, as shown in S38 of FIG. 14, the end of the spark-out is determined based on whether or not the set number of times has been rotated. Instead, the spark-out may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S38 of FIG. 14, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S38: Y), the spark-out is terminated. In this case, the end of the reverse grinding is determined based on whether or not the grinding resistance Ft has reached the set value Fε2, and the outer diameter Dt of the workpiece W described in the first modification of the fourth embodiment. Can be applied depending on whether or not has reached the set diameter Df1.

<Fifth embodiment>
The grinding method of 5th embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the fifth embodiment is a method in which the first forward grinding is executed, the backward grinding is subsequently executed, and then the spark-out is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. Then, at the end of the first forward grinding, the machining allowance Rε2 is left over the entire circumference of the workpiece W. This machining allowance Rε2 is set to be equal to or greater than the depth of the work-affected layer generated in the first forward grinding. Then, the work-affected layer depth is determined based on the measured value when measured during the first forward grinding, and is set based on the experimental results performed beforehand when not measured.

  In reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. In the backward grinding in this embodiment, the workpiece W is rotated a plurality of times. In each round of back grinding, the target grinding resistance Fe (θ) is set to be gradually reduced. Similarly to the third embodiment, when the end point of the reverse grinding reaches the resistance component Fε1 (hereinafter referred to as “dynamic pressure effect equivalent value”) caused by the influence of the dynamic pressure of the coolant fluid. It is said. Furthermore, in the spark-out, the dynamic pressure effect equivalent value Fε1 is taken into consideration.

  As shown in FIG. 17, from time t1 to time t4, that is, the first forward grinding is common to the third embodiment. However, the set outer diameter Dth in the present embodiment is represented by [Df−ωmax + Rε2]. Here, in order to determine the machining allowance Rε2, processing for estimating the depth of the work-affected layer generated by the first forward grinding is performed. This process can be estimated in advance according to the conditions of the first forward grinding, or the work-affected layer can be measured while performing the first forward grinding. For example, a known method using an eddy current sensor can be applied to the measurement of the work-affected layer. The machining allowance Rε2 is set to be equal to or greater than the estimated depth of the work-affected layer. That is, at the end of the first forward grinding (time t4 in FIG. 17), the machining allowance Rε2 equal to or greater than the estimated depth of the work-affected layer remains over the entire circumference.

  After the first forward grinding, reverse grinding is started. Here, the first back grinding is performed from time t4 to time t5 in FIG. Subsequently, the second backward grinding is performed from time t5 to time t6. Each backward grinding is performed while the workpiece W makes one rotation. At the end of the second backward grinding, the grinding resistance Ft is set to the dynamic pressure effect equivalent value Fε1. That is, the remaining grinding amount for the machining allowance Rε2 and the machining allowance Rε2 in the first forward grinding are ground by the first backward grinding and the second backward grinding. Then, when the second back grinding is finished, the spark-out is executed.

  Here, each back grinding of this embodiment will be described in detail with reference to FIG. As shown in FIG. 18, when the rotational phase θ of the workpiece W is 0 deg (corresponding to the “current rotational phase θt” of the present invention), the remaining grinding amount is E (0). The target grinding resistance at this time is set to Fe (0). The case where the rotational phase θ of the workpiece W is 0 deg is the start time of the first backward grinding.

  When the rotational phase θ of the workpiece W is 2πdeg (corresponding to the “target rotational phase θe” of the present invention), the target grinding resistance Fe (θe) is set to be Fe (1). This Fe (1) is smaller than Fe (0) and larger than the dynamic pressure effect equivalent value Fε1. Fe (1) is closer to Fε1 than Fe (0). The residual grinding amount at this time is E (1). Here, the case where the rotational phase θ of the workpiece W is 2πdeg is not only the end time of the first back grinding but also the start time of the second back grinding.

  When the rotational phase θ of the workpiece W is 4πdeg, the target grinding resistance Fe (θe) is set so as to be the dynamic pressure effect equivalent value Fε1. The remaining grinding amount at this time is E (θe). Here, the case where the rotational phase θ of the workpiece W is 4π deg is the end of the second backward grinding.

  This reverse grinding will be described in more detail with reference to FIG. The workpiece W at time t4 in FIG. 17 has a shape as shown in FIG. In FIG. 19, the rotation phase θ corresponds to the rotation phase θ of FIG. And the workpiece | work W in the time t5 of FIG. 17 becomes a shape as shown in FIG.19 (b). That is, as shown in FIGS. 19A and 19B, the amount of grinding in the second backward grinding is smaller than that in the first backward grinding. Then, the work W at time t5 in FIG. 17 has a substantially circular shape as shown in FIG.

  In this embodiment, the backward grinding is performed twice, but may be performed three or more times. In this case, the time change of the target grinding resistance Fe (θ) is preferably reduced as the number of times increases.

  According to the present embodiment, the backward grinding is performed by a plurality of rotations. In other words, the greater the number of times of reverse grinding, the more like the finish grinding. While performing reverse grinding, reverse grinding corresponding to rough grinding, reverse grinding corresponding to fine grinding, reverse grinding corresponding to fine grinding, and the like can be performed. As a result, it is possible to perform extremely accurate grinding. Furthermore, by setting the machining allowance Rε2 to be greater than or equal to the work-affected layer depth generated in the first forward grinding, the work-affected layer generated in the first forward grinding can be reliably removed in the backward grinding. Therefore, a work-affected layer is not generated on the cylindrical workpiece that has finished the reverse grinding. That is, the quality of the workpiece can be reliably improved.

<Sixth embodiment>
The grinding method of 6th embodiment is demonstrated with reference to FIGS. The grinding method in the grinder of the sixth embodiment is a method in which the first forward grinding is performed, the backward grinding is subsequently performed, and then the spark-out is performed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. However, in the first forward grinding, there is no steady state, or even if there is a steady state, the steady state does not exist for one rotation of the workpiece W. That is, in the reverse grinding, the target grinding resistance Fe (θ) is set to have a non-linear relationship without having a linear relationship with the rotational phase θ.

  First, referring to FIG. 20, when the steady state is present in the first forward grinding, the target grinding resistance Fe (θ) in the backward grinding, and the target grinding in the backward grinding when there is no steady state in the first forward grinding. The resistance Fe (θ) will be described. First, as shown in FIG. 20A, when there is a steady state in the first forward grinding, as described in the above embodiment, the target grinding resistance Fe (θ) is linear with respect to the elapsed time. It is set to have a relationship.

  On the other hand, as shown in FIG. 20B, when there is no steady state in the first forward grinding, the remaining grinding amount E (θ) does not have a linear relationship with the rotational phase θ. . Therefore, when the first forward grinding is finished, the amount of residual grinding with respect to the rotational phase θ has a non-linear relationship. Therefore, in the backward grinding, the target grinding resistance Fe (θ) is set so that the grinding amount corresponding to the remaining grinding amount by the first forward grinding is obtained at each rotational phase θ. Specifically, based on the grinding resistance Ft in the first forward grinding and the outer diameter Dt of the workpiece W, the target grinding resistance Fe (θ) in the backward grinding is calculated.

  Furthermore, when there is no steady state in the first forward grinding, it is not easy to determine the timing for switching from the first forward grinding to the backward grinding compared to the case where there is a steady state. On the other hand, in the present embodiment, the timing of switching from the first forward grinding to the backward grinding based on the grinding resistance Ft and the outer diameter Dt of the workpiece W during execution of the first forward grinding. Is determined.

  With reference to FIG. 21 and FIG. 22, the grinding method of this embodiment is demonstrated in detail. First forward grinding is started (S41). Here, the first forward grinding corresponds to the time t1 to t4 in FIG. Since this period is the same as that of the third embodiment, detailed description thereof is omitted.

  Subsequently, a dynamic pressure effect equivalent value Fε1 is calculated (S42). The dynamic pressure effect equivalent value Fε1 is calculated based on the outer diameter Dt of the workpiece W and the grinding resistance Ft in the transient state (time t2 to t3). Subsequently, the proportionality constant α is calculated based on the grinding amount per unit time of the workpiece W and the grinding resistance Ft (S43). The grinding amount per unit time of the workpiece W is calculated based on the outer diameter Dt of the workpiece W detected by the sizing device 60.

  Subsequently, the outer diameter Dm (hereinafter referred to as “switching outer diameter”) of the workpiece W corresponding to the current end point of the first forward grinding is calculated according to the equation (1) (S44). That is, the current switching outer diameter Dm is calculated based on the current grinding resistance Ft (t) detected by the force sensor 50 in addition to the previously calculated α and Fε1.

[Equation 1]
Dm = Df + (Ft (t) −Fε1) / α + [2Ft (t) −F (t−π / 2ω) −F (t−3π / 2ω)] (1)
Here, Df is the finishing diameter, Ft (t) is the grinding resistance Ft at the current time t, and ω is the angular velocity of the workpiece W.

  Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the calculated switching outer diameter Dm (S45). If the outer diameter Dt of the workpiece W has not yet reached the switching outer diameter Dm (S45: N), the first forward grinding is continued and the process returns to step S44 to again calculate (update the switching outer diameter Dm at the present time). ). On the other hand, when the outer diameter Dt of the workpiece W reaches the switching outer diameter Dm (S45: Y), the first forward grinding is finished (S46).

  Subsequently, reverse grinding is started (S47). That is, when the outer diameter Dt of the workpiece W reaches the switching outer diameter Dm, the first forward grinding is switched to the backward grinding. In this reverse grinding, a target grinding resistance Fe is set such that the remaining grinding amount E can be ground. Here, the grinding residual amount E can be expressed by the equation (2). Further, the target grinding resistance Fe can be expressed by Expression (3).

[Equation 2]
E (t) = E (t0) {1−ω / 2π * (t−t0)} + F (t−2π / ω) / α
(2)
Fe (t) = 2Ft (t0) −Ft (t−2π / ω) −ω / 2π * {Ft (t0) −Fε1} * (t−t0) (3)
Here, E (t) is the remaining grinding amount at time t, t is the current time, t0 is the time at which reverse grinding starts, and Fe (t) is the target grinding resistance at time t. . Since time t corresponds to the rotational phase θ, E (t) is substantially equivalent to E (θ), and Fe (t) is substantially equivalent to Fe (θ).

  Subsequently, it is determined whether or not the grinding resistance Ft has reached the dynamic pressure effect equivalent value Fε1 (S48). If the grinding resistance Ft does not reach the dynamic pressure effect equivalent value Fε1 (S48: N), the reverse grinding is continued. On the other hand, when the grinding resistance Ft reaches the dynamic pressure effect equivalent value Fε1 (S48: Y), the reverse grinding is finished (S49). The target grinding resistance Fe (θ) set in the above equation (3) is equal to the dynamic pressure effect equivalent value Fε1 at the end of the backward grinding (when the target rotational phase θe is reached). Is set to

  When the reverse grinding is finished, a spark out is executed (S50). This spark-out is performed with the grinding wheel 43 in a state where the cutting amount with respect to the workpiece W is zero. That is, at the spark-out, the position of the grindstone table 42 is shifted from the finishing diameter Df by a dimension corresponding to the dynamic pressure effect equivalent value Fε1. Then, this spark-out is performed for the number of rotations of the workpiece W set in advance. Therefore, it is determined whether or not the workpiece W has been rotated a set number of times (S51). If the workpiece W has been rotated the set number of times, the spark-out is terminated (S52).

  Here, the backward grinding of the present embodiment will be described in detail with reference to FIG. As shown in FIG. 23, when the rotational phase θ of the workpiece W is 0 deg (corresponding to the “current rotational phase θt” of the present invention), the remaining grinding amount is E (0). The target grinding resistance at this time is set to Fe (0). When the rotational phase θ of the workpiece W is 2πdeg (corresponding to the “target rotational phase θe” of the present invention), the target grinding resistance Fe (θe) is set to be a dynamic pressure effect equivalent value Fε1. The remaining grinding amount at this time is E (θe).

  According to the present embodiment, when the first forward grinding is finished, the remaining grinding amount E (θ) with respect to the rotational phase θ from the current rotational phase θt of the workpiece W to the target rotational phase θe is nonlinear. Even in such a case, the target grinding resistance Fe (θ) (or Fe (t)) in the reverse grinding can be set according to the remaining grinding amount E (θ) (or E (t)). That is, the grinding residue in the first forward grinding can be reliably ground in the backward grinding. Therefore, the grinding accuracy can be improved.

<First Modification of Sixth Embodiment>
In the sixth embodiment, as shown in S48 of FIG. 21, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached the dynamic pressure effect equivalent value Fε1. In addition, when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df, the reverse grinding may be terminated. That is, in S48 of FIG. 21, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S48: Y), the backward grinding is finished.

<Second Modification of Sixth Embodiment>
In the sixth embodiment, as shown in S51 of FIG. 21, the end of the spark-out is determined based on whether or not the set number of times has been rotated. Instead, the spark-out may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S51 of FIG. 21, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S51: Y), the spark-out is terminated. This is applied when the end of the reverse grinding is determined based on whether or not the grinding resistance Ft has reached the dynamic pressure equivalent value Fε1.

<Seventh embodiment>
The grinding method of 7th embodiment is demonstrated with reference to FIGS. The grinding method in the grinding machine of the fourth embodiment is a method in which the first forward grinding is executed, the backward grinding is subsequently executed, the second forward grinding is subsequently executed, and finally the spark-out is executed. In the first forward grinding, position control is performed to keep the feed rate of the grindstone table 42 constant. In the reverse grinding, control is performed such that the grinding resistance Ft becomes the target grinding resistance Fe. In the second forward grinding, constant grinding force control is performed so that the grinding resistance is constant. That is, in the second forward grinding, the grinding amount per unit time is controlled to be constant. In addition, at the end of the first forward grinding and the end of the backward grinding, the machining allowance Rε3 is left over the entire circumference of the workpiece W. That is, in the second forward grinding, the machining allowance Rε3 is ground.

  As shown in FIG. 24, the first forward grinding is started (S61). Here, the first forward grinding corresponds to the time t1 to t4 in FIG. Since it is the same as 1st embodiment during this period, detailed description is abbreviate | omitted. Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W has reached a preset outer diameter Dth (S62). Here, the set outer diameter Dth is represented by [Df−ωmax + Rε3]. That is, at the end of the first forward grinding (time t4 in FIG. 25), the machining allowance Rε3 remains over the entire circumference.

  If the outer diameter Dt of the workpiece W has not yet reached the set value Dth (S62: N), the first forward grinding is continued. On the other hand, when the outer diameter Dt of the workpiece W reaches the set value Dth (S62: Y), the first forward grinding is finished (S63).

  Subsequently, reverse grinding is started (S64). That is, when the outer diameter Dt of the workpiece W reaches the set value Dth, the first forward grinding is switched to the backward grinding. Subsequently, it is determined whether or not the grinding resistance Ft has reached the set value Fε3 (S65). Here, the set value Fε3 is a grinding resistance Ft in a state where the outer diameter Dt of the workpiece W becomes the set value Dth. That is, the target grinding resistance Fe (θ) is set so that the grinding resistance Ft becomes the set value Fε3 at the end of the backward grinding (when the target rotational phase θe is reached).

  If the grinding resistance Ft does not reach the set value Fε3 (S65: N), the reverse grinding is continued. On the other hand, when the grinding resistance Ft reaches the set value Fε3 (S65: Y), the reverse grinding is finished (S66).

  When the backward grinding is finished, the second forward grinding is started (S67). In the second forward grinding, the position of the grinding wheel base 42 is controlled so that the grinding resistance Ft is constant. Instead of position control, feedback control using the grinding resistance Ft can also be performed in the second forward grinding. The grinding resistance Ft controlled to be constant in the second forward grinding is set to a very small value compared to the maximum grinding resistance Ft in the first forward grinding. That is, when the first forward grinding is rough machining, the second forward grinding corresponds to finishing.

  Subsequently, it is determined whether or not the outer diameter Dt of the workpiece W has reached a preset outer diameter Dth2 (S68). Here, the set outer diameter Dth2 corresponds to the finished diameter. However, since the detected outer diameter Dt of the workpiece W varies slightly depending on the position detected by the sizing device 60, the outer diameter Dth2 is set in consideration of that amount. If the outer diameter Dt of the workpiece W has not yet reached the set value Dth2 (S68: N), the second forward grinding is continued. On the other hand, when the outer diameter Dt of the workpiece W reaches the set value Dth2 (S68: Y), the second forward grinding is finished (S69).

  Subsequently, a spark-out is executed (S70). This spark-out is performed with the grinding wheel 43 in a state where the cutting amount with respect to the workpiece W is zero. That is, in the spark-out, the remaining grinding is ground in the second forward grinding. Then, this spark-out is performed for the number of rotations of the workpiece W set in advance. Therefore, it is determined whether or not the workpiece W has been rotated a set number of times (S71). If the workpiece has been rotated the set number of times, the spark-out is terminated (S72).

  According to this embodiment, after the backward grinding, the second forward grinding is performed so that the grinding resistance Ft is constant. Thereby, even if a variation occurs in the backward grinding, the variation can be reliably removed by the second forward grinding. Therefore, highly accurate grinding can be realized.

  Further, after the second forward grinding, a spark out is performed. Here, the second forward grinding is forward grinding such that the grinding resistance is constant. Therefore, theoretically, it is considered that a step is generated between the portion where the second forward grinding is finished and the rotational phase θ positioned slightly ahead of the portion in the workpiece W. Therefore, the step can be removed by executing the spark-out. That is, even if a step is generated by the second forward grinding, the final ground surface can be made highly accurate by sparking out.

<First Modification of Seventh Embodiment>
In the seventh embodiment, as shown in S65 of FIG. 24, the end of the backward grinding is determined based on whether or not the grinding resistance Ft has reached the set value Fε3. In addition, when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches a set diameter Df3 (shown in FIG. 25), the reverse grinding may be terminated. That is, in S65 of FIG. 24, it is determined whether or not the outer diameter Dt of the work W detected by the sizing device 60 has reached the set diameter Df3, and the outer diameter Dt of the work W has reached the set diameter Df3. (S65: Y), the backward grinding is finished. The set diameter Df3 is the outer diameter Df of the workpiece W corresponding to the case where the grinding resistance Ft is the set value Fε3.

<Second Modification of Seventh Embodiment>
In the seventh embodiment, as shown in S71 of FIG. 24, the end of the spark-out is determined based on whether or not the set number of times has been rotated. Instead, the spark-out may be terminated when the outer diameter Df of the workpiece W detected by the sizing device 60 reaches the set finishing diameter Df. That is, in S71 of FIG. 24, it is determined whether or not the outer diameter Dt of the workpiece W detected by the sizing device 60 has reached the finishing diameter Df, and the outer diameter Dt of the workpiece W has reached the finishing diameter Df. (S71: Y), the spark-out is terminated.

<Others>
In the above embodiment, the force sensor 50 is used to detect the grinding resistance Ft. In addition, in order to detect the grinding resistance Ft, it is possible to use a driving torque for rotationally driving the workpiece W by the spindle motor 23. In this case as well, the same effects as in the above embodiment are achieved.

  Moreover, in the said embodiment, the case where the outer peripheral surface of the cylindrical workpiece W was ground was demonstrated. In addition, the present invention can be similarly applied to grinding the inner peripheral surface of the cylindrical workpiece W.

DESCRIPTION OF SYMBOLS 1: Grinding machine, 10: Bed, 20: Main spindle base, 21: Main spindle base, 22: Main spindle, 23: Main spindle motor, 24: Main spindle center, 30: Tailstock, 31: Tailstock main body, 32: Tailstock center 40: Whetstone support device, 41: Whetstone traverse base 42: Whetstone stand, 43: Whetstone wheel 50: Force sensor, 60: Sizing device, 70: Control device

Claims (20)

A grinding machine for grinding the outer periphery or inner periphery of a cylindrical workpiece,
With a grinding wheel,
A workpiece support means for rotatably supporting and driving the cylindrical workpiece;
Moving means for relatively moving the cylindrical workpiece and the grinding wheel so that the cylindrical workpiece and the grinding wheel approach or separate from each other;
Grinding resistance detection means for detecting a grinding resistance Ft generated by grinding the cylindrical workpiece by the grinding wheel;
First forward grinding control means for performing first forward grinding to increase the amount of deflection ω of the cylindrical workpiece by relatively moving the grinding wheel in a direction in which the grinding wheel is pressed against the cylindrical workpiece;
After the first forward grinding, during the backward grinding performed while the grinding wheel is relatively moved in a direction away from the cylindrical workpiece to reduce the amount of deflection ω of the cylindrical workpiece, the cylindrical workpiece Between the current rotational phase θt and the target rotational phase θe until the target rotational phase θe reaches the target rotational phase θe, based on the residual grinding amount E (θ) of the cylindrical workpiece at each rotational phase θ. target grinding resistance generating means for generating θ),
Reverse grinding control means for performing the backward grinding by controlling the grinding resistance Ft detected by the grinding resistance detection means to coincide with the target grinding resistance Fe (θ);
A grinding machine comprising: In claim 1,
The grinding machine according to claim 1, wherein the grinding resistance detection means is a force sensor provided in the workpiece support means. In claim 1,
The grinding machine according to claim 1, wherein the grinding resistance detecting means is a torque detecting means for detecting a driving torque for rotationally driving the cylindrical work by the work supporting means. In any one of Claims 1-3,
The first forward grinding control means performs the first forward grinding to a finishing diameter Df in at least a part of the cylindrical workpiece,
The grinding residual amount E (θ) at each rotational phase θ is a residual grinding amount with respect to the finishing diameter Df. In any one of Claims 1-3,
The first forward grinding control means performs the first forward grinding to a finishing diameter Df in at least a part of the cylindrical workpiece,
The residual grinding amount E (θ) at each rotational phase θ is a residual grinding amount with respect to the finishing diameter Df.
A grinding machine, further comprising a spark-out control means for performing a spark-out after setting the cutting amount of the grinding wheel with respect to the cylindrical workpiece to zero after the backward grinding. In any one of Claims 1-5,
The target grinding resistance generating means generates the target grinding resistance Fe (θ) so that the grinding resistance Ft becomes zero when the target rotational phase θe of the cylindrical workpiece is reached. Grinder. In any one of Claims 1-5,
When the target grinding resistance generating means reaches the target rotational phase θe of the cylindrical workpiece, the grinding resistance Ft corresponds to a dynamic pressure effect due to the coolant liquid between the cylindrical workpiece and the grinding wheel. The grinding machine is characterized in that the target grinding resistance Fe (θ) is generated so as to have a value Fε1. In claim 7,
The grinding machine
A sizing device for measuring the grinding diameter Dt of the cylindrical workpiece;
Estimation means for estimating a value Fε1 corresponding to the dynamic pressure effect, based on a reduction amount of the grinding diameter Dt of the cylindrical workpiece and the grinding resistance Ft detected by the grinding resistance detection means;
Further comprising
The target grinding resistance generating means generates the target grinding resistance Fe (θ) based on the estimated value Fε1 obtained by the estimating means. In claim 8,
The estimation means corresponds to the dynamic pressure effect based on the amount of decrease in the grinding diameter Dt of the cylindrical workpiece and the grinding resistance Ft in a transient state where the amount of deflection ω of the cylindrical workpiece is changing. A grinding machine characterized by estimating a value Fε1 to be performed. In any one of Claims 1-3,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε1 from the finishing diameter Df in at least a part of the cylindrical workpiece,
The residual grinding amount E (θ) in each rotational phase θ is a residual grinding amount with respect to a state in which the remaining margin Rε1 is left from the finishing diameter Df.
A grinding machine further comprising: a spark-out control means for grinding the remaining allowance Rε1 by spark-out after setting the cutting amount of the grinding wheel with respect to the cylindrical workpiece to zero after the backward grinding. In claim 10,
The target grinding resistance generating means is configured to provide the target grinding resistance Fe (θ) at each rotational phase θ so that the grinding resistance Ft becomes a predetermined value Fε2 when the target rotational phase θe of the cylindrical workpiece is reached. A grinding machine characterized by generating. In any one of Claims 1-11,
The grinding machine characterized in that the current grinding phase θt to the target revolution phase θe of the cylindrical workpiece in the target grinding resistance generating means is set to one rotation of the cylindrical workpiece. In any one of Claims 1-11,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε2 from the finishing diameter Df in at least a part of the cylindrical workpiece,
The grinding machine characterized in that the number of rotations of the cylindrical workpiece from the current rotation phase θt to the target rotation phase θe of the cylindrical workpiece in the target grinding resistance generating means is set. In claim 13,
A depth estimating means for estimating a depth of a work-affected layer generated in the first forward grinding;
The grinding machine according to claim 1, wherein the first forward grinding control means sets the remaining margin Rε2 to be equal to or greater than the work-affected layer depth and executes the first forward grinding. In any one of Claims 1-14,
Based on the grinding resistance Ft at each rotational phase θ measured at the time of the first forward grinding by the grinding resistance detection means, the grinding machine at each rotational phase θ at the end of the first forward grinding. A grinding residual amount estimating means for estimating a grinding residual amount E (θ) of the cylindrical workpiece;
The target grinding resistance generating means generates the target grinding resistance Fe (θ) based on the residual grinding amount E (θ) estimated by the residual grinding amount estimating means. In claim 15,
The remaining grinding amount estimation means is based on the grinding resistance Ft at each rotational phase θ and the grinding diameter Dt of the cylindrical workpiece at each rotational phase θ during the first forward grinding. A grinding machine characterized by estimating an amount E (θ). In any one of Claims 1-3,
The first forward grinding control means executes the first forward grinding so as to leave a margin Rε3 from the finishing diameter Df in at least a part of the cylindrical workpiece,
The grinder is the second forward after the backward grinding so that the grinding resistance Ft at each rotational phase θ becomes constant while moving the grinding wheel relative to the cylindrical workpiece. A grinding machine characterized by further comprising a grinding force constant forward grinding control means for performing grinding. In claim 17,
The grinding machine further comprises spark-out control means for performing spark-out after setting the cutting amount of the grinding wheel to the cylindrical workpiece to zero after the second forward grinding. In claim 1,
The reverse grinding control means switches from the first forward grinding to the backward grinding when the grinding diameter Dt of the cylindrical workpiece at a predetermined rotational phase θ reaches a set value. With a grinding wheel,
A workpiece support means for rotatably supporting and driving a cylindrical workpiece;
Moving means for relatively moving the cylindrical workpiece and the grinding wheel so that the cylindrical workpiece and the grinding wheel approach or separate from each other;
Grinding resistance detection means for detecting a grinding resistance Ft generated by grinding the cylindrical workpiece by the grinding wheel;
A grinding method comprising grinding an outer periphery or an inner periphery of the cylindrical workpiece,
A first forward grinding step of performing a first forward grinding for relatively moving the grinding wheel in a direction in which the grinding wheel is pressed against the cylindrical workpiece to increase a deflection amount ω of the cylindrical workpiece;
After the first forward grinding, during the backward grinding performed while the grinding wheel is relatively moved in a direction away from the cylindrical workpiece to reduce the amount of deflection ω of the cylindrical workpiece, the cylindrical workpiece Between the current rotational phase θt and the target rotational phase θe until the target rotational phase θe reaches the target rotational phase θe, based on the residual grinding amount E (θ) of the cylindrical workpiece at each rotational phase θ. θ) to produce a target grinding resistance process;
A reverse grinding step of controlling the grinding resistance Ft detected by the grinding resistance detection means to match the target grinding resistance Fe (θ) and executing the backward grinding;
A grinding method comprising:

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