JP2011143503A - Cylindrical grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the chattering of work W generated during the grinding of a cylindrical grinder 1. <P>SOLUTION: During grinding, a phase of chattering at a measuring point of a machined portion, work rotation speed, and the cycle of chattering are detected to calculate a present grinding action surface of a grinding wheel 7 at a grinding action point and a phase of relative displacement. The relative position of the work and the grinding wheel is displaced to a phase opposite to the calculated phase of the relative displacement by a relative position controlling means, reducing the chattering of the machined portion in process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cylindrical grinder, and more particularly, to reduction of chatter that is an unevenness with respect to an ideal shape distributed in a circumferential direction, which occurs in a workpiece portion of a workpiece as the workpiece is ground.

In a cylindrical grinder, a processing accuracy defect called chatter may occur. Chatter is a minute unevenness generated on the machining surface of the workpiece, and occurs when the relative position of the workpiece and the grinding wheel grinding surface fluctuates in vibration during one rotation of the workpiece. The wobbling of the grinding surface of the grinding wheel occurs when the grinding wheel is unbalanced or the grinding wheel rotation shaft vibrates. The vibration of the workpiece occurs when vibration is generated in the rotational drive unit of the workpiece or when the roundness of the center hole of the workpiece is poor. As described above, chattering occurs due to a change in the relative position of the workpiece and the grinding surface of the grinding wheel in which the grinding wheel vibration and the workpiece vibration are combined.
The feature of chattering is that it has periodicity due to the above-mentioned cause of occurrence, and in most cases, the main factor is runout of the grinding surface of the grinding wheel.

  Conventional chattering prevention techniques include the conventional technique 1 (for example, see Patent Document 1) that automatically corrects the grinding wheel unbalance in order to reduce the vibration of the grinding wheel, which is the cause of chattering, and the work surface of the workpiece. As a conventional technique 2 for correcting the relative displacement between the tool and the workpiece (for example, see Non-Patent Document 1).

  When the grinding wheel is unbalanced and shakes, if the truing is performed in this state, a grinding surface of the grinding wheel that is substantially free of shake with respect to the truer can be obtained. Therefore, by arranging the truing device at a position close to the workpiece, it is possible to reduce runout of the grinding surface of the grinding wheel with respect to the workpiece, and there are many such mechanical configurations. However, if the amount of unbalance varies with time, such as unbalance due to uneven distribution of coolant liquid absorbed by the grinding wheel, it is not possible to cope with the above configuration alone. In this case, an automatic balance device that automatically corrects the balance of the grinding wheel, such as the prior art 1 disclosed in Patent Document 1, is used.

The outline of the accuracy correction technique of the conventional technique 2 in the lathe processing described in Non-Patent Document 1 will be described below.
As shown in FIG. 12, a tool 41 is provided with a cutting tool 41 on one side of a rotating workpiece W, and a displacement detector 42 for measuring the relative position of the tool holding table 40 and the machining end surface of the workpiece W on the opposite side. In this structure, the cutting tool 41 is held so as to be movable in the cutting direction with respect to the table 40. During machining, the cutting tool 41 is moved in the cutting direction so as to cancel the relative displacement between the workpiece W and the tool holder 40 detected by the displacement detector 42, and the relative displacement due to the disturbance of the workpiece W and the tool 41 is reduced. This prevents deterioration of the machined surface accuracy such as chatter.

Japanese Patent Laid-Open No. 11-12531

“The Journal of Precision Engineering, Vol. 59, No. 6, 1993”, Precision Engineering Society, 1993, p. 87-p. 91

In the prior art shown in Patent Document 1, chattering due to vibration of a workpiece cannot be prevented, although chattering of the grinding wheel can be reduced to prevent chattering. Further, since the auto balance device incorporates a vibration detection device, a balance drive device, and the like into the grindstone shaft portion, the grindstone shaft portion becomes large and expensive. Furthermore, grinding must be interrupted during auto-balancing, and the operating rate decreases.
In the prior art shown in Non-Patent Document 1, errors due to the relative displacement between the grinding wheel holding portion and the workpiece can be reduced, but errors due to wobbling of the grinding wheel cannot be detected. As a result, chatter due to runout of the grinding surface of the grinding wheel cannot be reduced in-process.
In addition to the above, it is generally practiced to improve the accuracy by measuring the machining accuracy of the workpiece after completion of machining to determine the error and reworking it after correcting the error. Therefore, an extra process of reworking is required, and cost and processing time are increased.

  This invention is made | formed in view of the said situation, and it aims at providing the cylindrical grinder which reduces chatter by an in-process.

In order to solve the above-mentioned problem, the feature of the invention according to claim 1 is that a workpiece support means for supporting and rotating a cylindrical workpiece,
A grinding wheel support means for supporting and rotating the grinding wheel;
Driving means for relatively moving the workpiece support means and the grinding wheel support means and grinding the workpiece with the grinding wheel;
Phase detection means for detecting a phase at a grinding action point of chattering that is unevenness with respect to an ideal shape distributed in a circumferential direction generated in a workpiece portion of the workpiece as the workpiece is ground;
A relative position control means for displacing the relative displacement between the workpiece and the grinding wheel from the phase of the chatter at the grinding action point and the phase of the relative displacement between the workpiece and the grinding wheel;
It is to provide.

  A feature of the invention according to claim 2 is that in the invention according to claim 1, there is provided chatter amplitude detecting means for detecting the amplitude of the chatter of the workpiece, and the relative position control means is proportional to the amplitude of the chatter. It is to operate with the operating amount.

  A feature of the invention according to claim 3 is that, in the invention according to claim 2, the grinding is finished when the amplitude of the chatter of the workpiece becomes smaller than a predetermined value.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the phase detection unit is a chatter cycle detection unit that detects the cycle of the chatter of the workpiece,
Measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
From the chatter cycle detected by the chatter cycle detector, the chatter phase detected by the measurement point phase detector, and the rotational speed of the workpiece detected by the rotational speed detector, the workpiece A chatter calculating means for calculating a phase of the chatter at the grinding action point of the object;
It is composed of.

A feature of the invention according to claim 5 is that, in the invention according to any one of claims 1 to 3, the phase detection means includes a grinding wheel rotation period detection means for detecting a rotation period of the grinding wheel,
The measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
The rotation cycle of the grinding wheel detected by the grinding wheel rotation cycle detection means, the chatter phase detected by the measurement point phase detection means, and the rotation speed of the workpiece detected by the rotation speed detection means And a chatter calculating means for calculating a phase of the chatter at the grinding action point of the workpiece from
It is composed of.

The invention according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 3, the phase detection means comprises a grinding wheel vibration period detection means for detecting a vibration period of the grinding wheel support means,
Measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
The vibration cycle of the grinding wheel support means detected by the grinding wheel vibration period detection means, the chatter phase detected by the measurement point phase detection means, and the rotation of the workpiece detected by the rotation speed detection means A chatter calculating means for calculating the chatter phase at the grinding action point of the workpiece from the speed;
It is composed of.

  According to a seventh aspect of the present invention, in the invention according to any one of the first to third aspects, the phase detection means is a vibration phase of the grinding wheel in the grinding wheel of the grinding wheel of the grinding wheel support means. It is comprised with the grindstone vibration phase detection means which detects this.

  A feature of the invention according to claim 8 is that, in the invention according to any one of claims 1 to 7, the relative position control means is constituted by a workpiece displacement means for displacing the workpiece.

A feature of the invention according to claim 9 is that, in the invention according to claim 8, the workpiece displacing means is brought into contact with the workpiece portion of the workpiece at a position 180 degrees out of phase with the grinding action point of the workpiece. It consists of a workpiece pressing device that presses
From the amount of displacement that causes the workpiece pressing device to be displaced in a phase opposite to the phase of relative displacement between the workpiece and the grinding wheel determined from the chatter phase at the grinding action point, the workpiece pressing device is It is controlling by the value which subtracted the uneven | corrugated height of the said chatter in the to-be-processed part of the said workpiece which contacts.

  A feature of the invention according to claim 10 is that, in the invention according to claim 9, a piezoelectric element is used for driving the relative position control means.

  A feature of the invention according to claim 11 is that, in the invention according to claim 4, the chatter cycle detecting means is constituted by detecting the period of the irregularities by means of the irregularity detecting means for detecting irregularities of the workpiece. is there.

  According to a twelfth aspect of the present invention, in the invention according to any one of the second to sixth aspects, the amplitude of the unevenness is detected by the unevenness detecting means for detecting the unevenness of the processed part. It is constituted by detecting.

  According to a thirteenth aspect of the present invention, in the invention according to any one of the fourth to sixth aspects, the measurement point phase detection means can detect the unevenness by means of an unevenness detection means that detects the unevenness of the workpiece. It is configured by detecting the phase.

  A feature of the invention according to claim 14 is that, in the invention according to any one of claims 11 to 13, it is arranged so that the unevenness detecting means and the lower part of the part to be processed are in contact with each other.

  According to the first aspect of the present invention, the phase of the chatter generated by the relative displacement between the grinding surface of the grinding wheel and the workpiece is detected by the phase detection means at the grinding action point during grinding, and the chatter is detected by the relative position control means. By causing the grinding wheel and the workpiece to move relative to each other in a phase opposite to the relative displacement, the chattering amplitude can be reduced. Since the above operation can be performed in-process, an extra step for reducing chatter is unnecessary, and an increase in processing time can be prevented.

  According to the invention which concerns on Claim 2, a relative position control means can be operated by the optimal amplitude which negates the amplitude of the chatter currently generated, and a chatter reduction effect can be enlarged.

  According to the invention which concerns on Claim 3, grinding can be complete | finished when the amplitude of the chatter of a to-be-processed part becomes smaller than predetermined value, and the workpiece of the desired surface precision can be processed in the shortest time.

  According to the invention which concerns on Claim 4, since a relative position control means is operated based on the actual chatter of a to-be-processed part, chatter can be reduced with respect to chatter of any cause.

  According to the fifth aspect of the present invention, since the rotation cycle of the grinding wheel that can be detected by a simple grinding wheel rotation cycle detection unit is used as the chatter cycle necessary for the configuration of the phase detection unit, the phase detection unit can be reduced in cost. Can be configured.

  According to the sixth aspect of the present invention, since the vibration cycle of the grinding wheel platform that can be detected by a simple grinding wheel platform vibration cycle detection unit is used as the chatter cycle necessary for the configuration of the phase detection unit, the phase detection unit can be reduced in cost. Can be configured.

  According to the seventh aspect of the invention, since the simple grindstone vibration phase detection means is used as the phase detection means, the phase detection means can be configured at low cost.

  According to the invention which concerns on Claim 8, a relative position control means can be comprised by displacing a workpiece | work with small mass with respect to a grinding wheel, and chatter reduction control with high responsiveness can be performed. For this reason, chatter can be reduced even in high-efficiency grinding where the grinding wheel rotates at high speed.

  According to the ninth aspect of the present invention, the relative position control means is brought into contact with the workpiece and the work piece is displaced. Therefore, the present invention can be implemented without providing a special contact portion of the relative position control means on the work piece. . Further, it can have a steadying function for supporting the grinding resistance in the normal direction of the grinding wheel to prevent the workpiece from being bent.

  According to the invention of claim 10, since the piezoelectric element is used for driving the relative position control means, the relative position control means capable of high response and high load control can be configured compactly.

  According to the eleventh aspect of the present invention, since the chatter cycle is detected by the projection / depression detecting means for detecting the projection / depression of the workpiece, an accurate chatter cycle can be detected, and highly accurate chatter reduction control is possible.

  According to the twelfth aspect of the invention, since the chatter amplitude is accurately detected by detecting the amplitude of the unevenness of the workpiece by the unevenness detecting means, it is possible to operate the relative position control means with the optimum amplitude, and the effect The chatter can be reduced.

  According to the thirteenth aspect of the present invention, since the chatter phase of the workpiece is accurately detected by the unevenness detecting means, it is possible to operate the relative position control means of the opposite phase with a small phase error, and effectively reduce chatter. Can do.

  According to the invention of claim 14, since the unevenness detecting means and the lower part of the workpiece are arranged so as to be in contact with each other, the steady rest that prevents the workpiece from bending downward due to its own weight and grinding resistance. It can have both functions.

It is the schematic which shows the whole structure of the cylindrical grinding machine of 1st Embodiment. FIG. 2 is a top view of FIG. 1. It is the schematic which shows the unevenness | corrugation detection apparatus and workpiece pressing apparatus of 1st Embodiment. It is the schematic which shows the element arrangement | positioning of 1st Embodiment. It is a block diagram which shows the relationship between the grinding action point chatter detection means and workpiece pressing apparatus of 1st Embodiment. It is a conceptual diagram which shows the chatter phase detection principle of 1st Embodiment. It is a table | surface which shows the relationship of the data of 1st Embodiment. It is a flowchart figure which shows the chatter reduction operation | movement of 1st Embodiment. It is a block diagram which shows the relationship between the grinding action point chatter detection means and workpiece pressing apparatus of 2nd Embodiment. It is a block diagram which shows the relationship between the grinding action point chatter detection means and workpiece pressing apparatus of 3rd Embodiment. It is a block diagram which shows the relationship between the grinding action point chatter detection means and workpiece pressing apparatus of 4th Embodiment. It is a conceptual diagram which shows the principle of the prior art 2. FIG.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6 based on an implementation example of a cylindrical grinder for grinding a cylindrical workpiece.
As shown in FIG. 2, the grinding machine 1 includes a bed 2, a grindstone bed 3 that can reciprocate on the bed 2 in the X-axis direction, and a table 4. The grinding wheel base 3 includes a grinding wheel shaft rotating motor (not shown) that rotatably supports the grinding wheel shaft 8 and rotates the grinding wheel shaft 8. The grinding wheel 7 is detachably mounted on the grinding wheel shaft 8 and is driven to rotate. Is done. On the table 4, a spindle 5 that grips and rotatably supports one end of the workpiece W and is rotated by a spindle motor (not shown), and a tailstock that rotatably supports the other end of the workpiece W. A work table W is provided, and the workpiece W is supported by the spindle 5 and the tailstock 6 and is driven to rotate during grinding.
As shown in FIG. 1, a gantry 9 is installed on the table 4, and a concavo-convex detection device 10 that detects the concavo-convex of the workpiece by contacting the lower portion of the workpiece W with the gantry 9, and the workpiece A workpiece pressing device 11 that holds the workpiece W in contact with the workpiece at a position opposite to the grinding action point on the outer periphery of the portion and applies displacement to the workpiece W to control the relative position between the grinding wheel 7 and the workpiece W is held.

  The grinding machine 1 includes a control device 30 that executes automated grinding by executing a predetermined program. As a functional configuration of the control device 30, an X-axis control means 31 that controls the feed of the grinding wheel table 3, a spindle control means 32 that controls the rotation of the spindle 5, and a grinding action point chatter detection means 33 that detects chatter at the grinding action point. Further, a workpiece pressing control means 34 for controlling the workpiece pressing device 11 is provided. The main shaft control means 32 is provided with main shaft rotation speed detection means 321 for detecting the rotation speed of the main shaft 5.

As shown in FIG. 3, the unevenness detecting device 10 includes a piezoelectric element 101 whose bottom is fixed to the gantry 9, a plunger 102 that is joined to the top of the piezoelectric element 101 and can be slidably moved up and down with respect to the gantry 9, The contact 103 is attached to the tip of the plunger 102 and contacts the workpiece W. The piezoelectric element 101 generates a voltage corresponding to fluctuations in the contact force due to chatter irregularities accompanying the rotation of the workpiece, and sends a detection signal to the control device 30 via the voltage detector 12.
The workpiece pressing device 11 includes a piezoelectric element 111 having one end fixed to the gantry 9, a plunger 112 joined to the other end of the piezoelectric element 111 and capable of sliding back and forth with respect to the gantry 9, and a tip of the plunger 112. It is comprised with the contactor 113 with which it mounts | wears and contacts the workpiece W. The piezoelectric element 111 is driven by the control device 30 via the piezoelectric element driver 13.

The action of reducing chatter by the cylindrical grinder as described above will be described below with reference to FIGS.
As shown in FIG. 4, the contact 103 of the unevenness detecting device 10 is always in contact with the lower part of the workpiece W of the workpiece W at the unevenness detection position where the angle from the grinding action point in the rotation direction of the workpiece is α degrees. To be arranged. The contact 113 of the workpiece pressing device 11 is always in contact with the workpiece at a workpiece pressing position opposite to the grinding action point of the workpiece W whose angle to the unevenness detection position is β degrees in the rotation direction of the workpiece. Placed in.
The unevenness detection device 10 detects a load change accompanying the unevenness change of chatter due to the rotation of the workpiece by the piezoelectric element 101 and outputs it to the voltage detector 12 as a voltage. At this time, the load fluctuation is proportional to the amplitude of chatter and becomes maximum at the apex of the convex part and becomes minimum at the concave part, and the voltage output similarly varies.

In order to reduce chatter, it is necessary to detect the phase, period and amplitude of chatter at the current grinding action point.
As shown in FIG. 5, in this embodiment, the period and amplitude of the unevenness detected at the unevenness detection position by the unevenness detection device 10 are set as the chatter period and amplitude at the grinding action point. The chatter cycle T is detected as a time (second) of one cycle of voltage fluctuation detected by the unevenness detection device 10. Since the amplitude of chatter is proportional to the voltage output fluctuation range, it is detected by converting the voltage fluctuation range into amplitude from a predetermined conversion ratio.
The phase is calculated by the following method from the phase and period at the unevenness detection position and the rotational speed of the workpiece. The chattering of the workpiece W generated at the grinding point due to the relative displacement between the grinding surface of the workpiece W and the grinding wheel 7 passes through the workpiece pushing position by the rotation of the workpiece W, and further reaches the unevenness detection position. FIG. 6 is a diagram showing a relative relationship among a grinding action point, a workpiece pushing position, and a concavo-convex detection position developed on a straight line with the convex part of chatter generated on the circumferential surface of the work part being positive and the concave part being negative. It is.
In FIG. 6, the angle difference α between the grinding point and the unevenness detection position is represented by a phase difference Φ1 with the chatter period as a unit, and the angle difference β between the workpiece pushing position and the unevenness detection position with the chatter period as a unit. This is represented by a phase difference Φ2. If the chatter period is T (seconds) and the rotation speed of the workpiece is N rotations, the phase difference Φ1 of the angle α is expressed as Φ1 = 2π · α / (360 · N · T), and the angle β The phase difference Φ2 is expressed as Φ2 = 2π · β / (360 · N · T). When the chatter phase at the unevenness detection position is ω and the amplitude is a, the chatter phase at the grinding action point is ω−Φ1, and the chatter phase at the workpiece pushing position is ω−Φ2. The vibration fluctuation of the chatter at the grinding action point is represented by a · sin (ω−Φ1), and is represented by a · sin (ω−Φ2) at the workpiece pushing position.

If the operation of the contactor 113 of the workpiece pressing device 11 in the direction in which the workpiece is brought closer to the grinding wheel 7 is positive, the displacement given to the workpiece to cancel chatter is the grinding action surface of the grinding wheel at the grinding action point. Since it is in phase opposite to the relative displacement of the workpiece, a · sin (ω−Φ1), which is in phase with chatter. However, in grinding, elastic deformation occurs in each part of the grinder between the grinding wheel grinding point and the workpiece machining point, so that the pushing operation of the workpiece does not directly change the actual grinding removal depth, and the removal depth is reduced by the elastic deformation. A correction coefficient K1 is used to correct the fluctuation. The corrected operation amount d of the contactor 113 is d = K1 · a · sin (ω−Φ1).
In the present embodiment, the workpiece W is displaced by pushing the workpiece at a position where the angle from the grinding action point is α−β. In this case, if the workpiece is a perfect circle, the correction operation amount d may be given as the displacement of the contact 113 of the workpiece pressing device 11. However, since irregularities are generated in the workpiece due to chattering, a displacement corresponding to the amplitude of the irregularities is generated in the workpiece W even when the contactor 113 of the workpiece pressing device 11 is stationary. For this reason, the displacement K1 · a · sin (ω−Φ2 + π) having a phase opposite to the chattering phase at the workpiece pushing position is added to the operation amount of the contactor 113 of the workpiece pushing device 11, thereby It is necessary to cancel the increase / decrease in the pressing amount due to the unevenness. This addition is performed until the α-β angle workpiece rotates after chatter correction with large chatter of the workpiece is started.

From the above, assuming that Φ1, Φ2, a, and ω that are first detected and calculated are Φ1 ₁ , Φ2 ₁ , a ₁ , and ω ₁ , the first correction data equation d ₁ is α− Until the angle workpiece of β rotates, d ₁ = K1 · a ₁ · (sin (ω ₁ −Φ1 ₁ ) + sin (ω ₁ −Φ2 ₁ + π)). rotation angle workpiece alpha-beta, the correction data type d ₁ after reduced the processing surface of the chatter reaches the workpiece push-in position _{is, d 1 = K1 · a 1} · sin (ω 1 -Φ1 ₁ ). Create data corresponding with the rotational position of the workpiece by the data type d ₁ above, to operate the workpiece pressing device 11 on the basis of this data.

Correction data d ₂ when the reduction of chatter adds a second compensation not sufficient to create as follows.
Since the chatter of the work surface is smaller than the first time, the first correction data d ₀ = K1 · a ₁ · sin (ω ₁ −Φ1 ₁₎ is ignored, ignoring the increase / decrease of the indentation amount due to the chatter effect of the work surface. ) For one rotation of the workpiece. Next, Φ1, a and ω detected and calculated after the first correction are Φ1 ₂ , a ₂ and ω ₂ , and d _s = K1 · a ₂ · sin (ω ₂ −Φ1 ₂ ) is calculated for one rotation of the workpiece. To do. d ₀ and d _s are stored as data corresponding to the rotational position of the workpiece, and data obtained by adding d ₀ and d _s for each rotational position of the workpiece is defined as d ₂ . The relationship between the workpiece rotation position θ and ω ₁ , ω ₂ , d ₁ , d _s is shown in FIG.

The chatter reduction operation of the present invention is effective when the cutting amount of the grinding wheel per work rotation in the grinding cycle is small, particularly when it is operated during spark-out grinding when the cutting of the grinding wheel is stopped. The effect is remarkable. The chatter reduction operation in the spark-out cycle will be described based on the flowchart of FIG.
First, by detecting the spindle rotational speed, the rotational speed of the workpiece W held and rotating by the spindle 5 is detected (STP1).
Next, detecting the period _{T 1} and an amplitude _{a 1} of chatter of the workpiece W by the unevenness detecting device 10 (STP2). Period T ₁ is a time of one cycle of the voltage decrease due to the unevenness of the chatter, the amplitude a ₁ is calculated as the product of the voltage fluctuation range and the coefficient K2. As the coefficient K2, a value determined in advance by the workpiece rotational speed and the workpiece mass is input as data.
The phase differences Φ1 and Φ2 are calculated as Φ1 ₁ = 2π · α / (360 · N · T ₁ ) and Φ2 ₁ = 2π · β / (360 · N · T ₁ ) (STP3).
Drive data d ₁ of the workpiece pressing device 11 is created. When ω ₁ is Φ1−Φ2, d ₁ = K1 · a ₁ · (sin (ω ₁ −Φ1 ₁ ) + sin (ω ₁ −Φ2 ₁ + π)) When ω ₁ is Φ1−Φ2 and thereafter, d ₁ = K1 · a ₁ · sin (ω ₁ −Φ1 ₁ ). The chatter phase ω ₁ is converted into a workpiece rotation angle θ and stored in a drive data table in which d ₁ and the workpiece rotation angle θ are associated with each other (STP4). Here, the start positions are ω ₁ = 0 and θ = 0.

The unevenness detecting device 10 detects the phase ω ₁ = 0 (STP5).
While the workpiece pressing device 11 is driven by the displacement d ₁ based on the workpiece rotation in the drive data table with the workpiece rotation position of ω ₁ = n · 2 · π (n is an integer) as the start position, the workpiece is moved to 1 Rotate (STP6).
After the workpiece after chatter correction start is rotated above alpha, it detects a chatter amplitude a ₂ (STP7).
Determining chatter amplitude _{a 2} is whether the target value or less (STP8).
If chatter amplitude a ₂ is larger than the target value, chatter cycle T ₂ , chatter amplitude a ₂ and phase ω ₂₀ of ω _{2 at} θ = 0 are detected (STP 9).
The phase difference Φ1 is calculated as Φ1 ₂ = 2π · α / (360 · N · T ₂ ) (STP10).
It is assumed that d ₁ = K1 · a ₁ · sin (ω ₁ −Φ1 ₁ ) and d _s = K1 · a ₂ · sin (ω ₂ −Φ1 ₂ ). The chatter phases ω ₁ and ω ₂ are converted into the workpiece rotation angle θ, and the values of d ₁ and d _s corresponding to the same workpiece rotation angle θ are added to obtain correction data d ₂ and stored in the drive data table. (STP11).
When the workpiece rotation angle θ at the grinding point is 0, the driving of the workpiece pressing device 11 based on the _second correction data d2 is started, and the workpiece is rotated once (STP6).
Thereafter, (STP7) and (STP8) are executed, and when the chatter amplitude becomes equal to or smaller than the target value, the grindstone table 3 is moved backward to finish grinding (STP12).

<Second Embodiment>
In the first embodiment, the chatter cycle is detected by detecting one cycle of the chatter unevenness of the workpiece, but most of the chattering is caused by a change in displacement due to rotation of the grinding surface of the grinding wheel 7. Therefore, the chatter phase may be calculated using the grindstone rotation cycle as the chatter cycle.
As shown in FIG. 9, in this embodiment, the amplitude of the unevenness detected at the unevenness detection position by the unevenness detection device 10 is set as the amplitude of chatter at the grinding action point. As the chatter cycle T, the grinding wheel rotational speed detection means 35 detects the time (seconds) that the grinding wheel 7 makes one rotation. The grinding wheel rotational speed detection means 35 can be realized by attaching a rotational speed sensor to the grinding wheel shaft, or a command value to the grinding wheel shaft rotation motor can be used regardless of the actual measurement value.
The phase at the grinding action point is calculated in the same manner as in the first embodiment, using the chatter phase at the unevenness detection position, the rotation cycle of the grinding wheel 7 and the rotation speed of the workpiece.
The chatter reduction operation is also performed in the same manner as in the first embodiment.

<Third Embodiment>
Since the grinding wheel base 3 is vibrated when the radial position varies with the rotation of the grinding surface of the grinding wheel 7, the chatter phase may be calculated using the vibration cycle as the chatter cycle.
As shown in FIG. 10, in this embodiment, the amplitude of the unevenness detected at the unevenness detection position by the unevenness detecting device 10 is set as the amplitude of chattering at the grinding action point. As the chatter cycle T, the grindstone vibration cycle detecting means 36 detects the vibration cycle (second) in the cutting direction of the grinding wheel 7 of the grindstone table 3. The grindstone vibration period detecting means 36 can be realized by attaching a vibration sensor to the grindstone table 3.
The phase at the grinding action point is calculated in the same manner as in the first embodiment, using the chattering phase at the unevenness detection position, the vibration cycle of the grinding wheel table 3, and the rotational speed of the workpiece.
The chatter reduction operation is also performed in the same manner as in the first embodiment.

<Fourth Embodiment>
As shown in FIG. 11, in this embodiment, the amplitude of the unevenness detected at the unevenness detection position by the unevenness detection device 10 is set as the amplitude of chatter at the grinding action point. As the chatter cycle T, the grindstone vibration cycle detecting means 36 detects the vibration cycle (second) in the cutting direction of the grinding wheel 7 of the grindstone table 3. The phase at the grinding action point of chattering is detected by the grinding wheel base vibration phase detecting means 37 with a phase in which the grinding wheel head retreating direction of the grinding wheel 7 in the cutting direction of the grinding wheel base 3 is positive. The grinding wheel base vibration phase detection means 37 can be realized by attaching a vibration sensor to the grinding wheel base 3 and can also serve as the vibration sensor of the grinding wheel base vibration period detection means 36.
The chatter reduction operation is also performed in the same manner as in the first embodiment.

<Modification of First to Fourth Embodiments>
In the first to fourth embodiments, the workpiece is displaced by pushing the workpiece of the workpiece W. However, in this case, the headstock and the tailstock that hold the workpiece may be provided with a displacement means. The corrected displacement d is d = K1 · a · sin (ω−Φ1).
In the first to fourth embodiments, the chatter amplitude a is detected by the voltage fluctuation of the piezoelectric element 101, but the radius fluctuation of the workpiece may be detected by a displacement meter to obtain the chatter amplitude a.
In the first to fourth embodiments, the workpiece W is displaced to control the relative position between the workpiece W and the grinding wheel 7, but the grinding wheel may be displaced. In order to displace the grinding wheel, for example, it is possible to vary the pressure of the static pressure pocket portion in the grinding wheel cutting direction of the static pressure bearing of the grinding wheel.

1: Cylindrical grinding machine 3: Grinding wheel base W: Work piece 5: Main shaft 6: Tailstock 7: Grinding wheel 8: Grinding wheel shaft 10: Concavity and convexity detection device 11: Workpiece pressing device 111: Piezoelectric element 33: Grinding action point chatter Detection means 35: Grinding wheel rotational speed detection means 36: Wheel head vibration period detection means 37: Wheel head vibration phase detection means 321: Spindle speed detection means

Claims (14)

A workpiece support means for supporting and rotating the cylindrical workpiece;
A grinding wheel support means for supporting and rotating the grinding wheel;
Driving means for relatively moving the workpiece support means and the grinding wheel support means and grinding the workpiece with the grinding wheel;
Phase detection means for detecting a phase at a grinding action point of chattering that is unevenness with respect to an ideal shape distributed in a circumferential direction generated in a workpiece portion of the workpiece as the workpiece is ground;
A relative position control means for displacing the relative displacement between the workpiece and the grinding wheel from the phase of the chatter at the grinding action point and the phase of the relative displacement between the workpiece and the grinding wheel;
A cylindrical grinding machine.   The cylindrical grinding machine according to claim 1, further comprising a chatter amplitude detecting unit that detects the chatter amplitude of the workpiece, and operating the relative position control unit with an operation amount proportional to the chatter amplitude.   The cylindrical grinding machine according to claim 2, wherein the grinding is finished when an amplitude of the chatter of the workpiece becomes smaller than a predetermined value. The chatter cycle detection unit that detects the chatter cycle of the workpiece, the phase detection unit;
Measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
From the chatter cycle detected by the chatter cycle detector, the chatter phase detected by the measurement point phase detector, and the rotational speed of the workpiece detected by the rotational speed detector, the workpiece A chatter calculating means for calculating a phase of the chatter at the grinding action point of the object;
The cylindrical grinding machine of any one of Claims 1-3 comprised by these. Grinding wheel rotation period detection means for detecting the rotation period of the grinding wheel;
The measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
The rotation cycle of the grinding wheel detected by the grinding wheel rotation cycle detection means, the chatter phase detected by the measurement point phase detection means, and the rotation speed of the workpiece detected by the rotation speed detection means And a chatter calculating means for calculating a phase of the chatter at the grinding action point of the workpiece from
The cylindrical grinding machine of any one of Claims 1-3 comprised by these. Grinding wheel vibration period detecting means for detecting the vibration period of the grinding wheel support means, the phase detection means,
Measurement point phase detection means for detecting the phase of the chatter at a measurement point which is a predetermined circumferential position on the outer periphery of the workpiece;
Rotation speed detection means for detecting the rotation speed of the workpiece;
The vibration cycle of the grinding wheel support means detected by the grinding wheel vibration period detection means, the chatter phase detected by the measurement point phase detection means, and the rotation of the workpiece detected by the rotation speed detection means A chatter calculating means for calculating the chatter phase at the grinding action point of the workpiece from the speed;
The cylindrical grinding machine of any one of Claims 1-3 comprised by these.   The said phase detection means is comprised with the grindstone vibration phase detection means which detects the vibration phase of the said workpiece cutting direction of the said grinding wheel of the said grinding wheel support means, The any one of Claims 1-3. Cylindrical grinding machine.   The cylindrical grinding machine according to any one of claims 1 to 7, wherein the relative position control means is constituted by a workpiece displacement means for displacing the workpiece. The workpiece displacing means comprises a workpiece pressing device that contacts and presses the workpiece to be processed at a position 180 degrees out of phase with the grinding point of the workpiece;
From the amount of displacement that causes the workpiece pressing device to be displaced in a phase opposite to the phase of relative displacement between the workpiece and the grinding wheel determined from the chatter phase at the grinding action point, the workpiece pressing device is The cylindrical grinding machine according to claim 8, wherein the cylindrical grinder is controlled by a value obtained by subtracting the uneven height of the chattering in a workpiece portion of the workpiece to be contacted.   The cylindrical grinding machine according to claim 9, wherein a piezoelectric element is used to drive the relative position control means.   The cylindrical grinding machine according to claim 4, wherein the chatter cycle detecting unit is configured to detect a cycle of the unevenness by an unevenness detecting unit that detects the unevenness of the workpiece.   The cylindrical grinder according to any one of claims 2 to 6, wherein the chatter amplitude detecting means is configured by detecting the amplitude of the unevenness by an unevenness detecting means for detecting unevenness of the workpiece.   The cylindrical grinding machine according to any one of claims 4 to 6, wherein the measurement point phase detection unit is configured to detect a phase of the unevenness by an unevenness detection unit that detects unevenness of the workpiece. .   The cylindrical grinder according to any one of claims 11 to 13, wherein the cylindrical grinder is disposed so that the unevenness detecting means and a lower portion of the workpiece are in contact with each other.

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