JP7500133B2 - Method for correcting imbalance by evaluating vibration in three-dimensional positions and machine tool capable of automating said method - Google Patents

Description

The present invention relates to a method for correcting imbalance by evaluating vibrations in three-dimensional positions and a machine tool that can automate this method, and in particular, to a mechanism that performs corrections to address imbalance in order to prevent vibrations caused by imbalance inherent in a tool and its rotating shaft when using a rotating tool that includes a grinding wheel.

Conventionally, when using a rotating tool including a grinding wheel, vibrations occur depending on the balance state of the tool, which is called unbalance. This unbalance may be inherent not only in the tool but also in the rotating shaft itself that rotates the tool. When this vibration becomes a problem, a correction mechanism to deal with this unbalance is often provided on the tool or rotating shaft side. The reality of balancing is to add a weight that generates vibration to the rotating body so that the vibration superposition approaches zero at the position of some vibration sensor (displacement meter, speed meter, or accelerometer) used for evaluation. Due to this reality, it may happen that the vibration appears to be zero at the sensor position, but the vibration of the tip of the tool cannot be suppressed. In addition, when a bending moment is generated by centrifugal force, a state may occur in which the vibration does not become zero depending on the rotation speed. Therefore, redundant sensors are generally provided and a numerical optimization method such as the least squares method is used to attach weights in a direction that approaches zero for all sensors, or in a direction that approaches zero at all rotation speeds (for example, see Non-Patent Document 1).

In addition, it is common to provide multiple correction planes in the direction of the rotation axis to deal with bending moments. In the case of a rigid rotor, the unbalance is constant depending on the rotation speed, but in an actual elastic rotor, the unbalance can change depending on the rotation speed. Also, due to the relationship between the natural frequency, the magnitude of vibration usually changes even with the same unbalance depending on the tool position (the relative position of the workpiece and the spindle). For this reason, the unbalance is usually evaluated with the position and rotation speed constant, and then corrected to cancel it out. The following non-patent document 1 relates to a known technique for vibration analysis of rotating machines used in the present invention, and will be cited in the explanation of the present invention below.

Vibration of Rotating Machinery - Fundamentals of Practical Vibration Analysis (by Osami Matsushita et al.), Corona Publishing, October 2, 2009

However, when a workpiece is being machined using a machine tool, the rotation speed of the tool's rotation axis is also changed, and the machining position of the workpiece using the tool also shifts. Therefore, there is a strong demand for the development of technology that can perform imbalance correction so that the result is uniformly good at all positions and rotation speeds. There is also a demand for the development of machine tools that are equipped with an automatic imbalance correction mechanism to fully automate the correction of imbalance.

The present invention was made in light of the above-mentioned circumstances, and its purpose is to provide technology that can perform uniform and good imbalance correction at any position and rotation speed while a workpiece is being machined by a machine tool. Another purpose of the present invention is to provide a machine tool that is equipped with an automatic imbalance correction mechanism and that fully automates the correction of imbalance.

The inventors have conducted extensive research into technology that can correct imbalance so that it is uniformly good at any position and rotation speed while the machine tool is machining a workpiece, and as a result, by applying the technology described in Non-Patent Document 1 above, have come up with a new and useful idea for the configuration of such a machine tool and its method of correcting imbalance.

In the present invention, the technique described in Non-Patent Document 1 is used to determine a three-dimensional (not linear) position around the range of movement during machining, evaluate the imbalance using a combination of the rotation speed and position used during machining, and perform a certain weighting, and perform unbalance correction using a numerical optimization method so that the vibration is uniformly good at any position and rotation speed. Also, a machine tool is configured that is equipped with an automatic imbalance correction mechanism to fully automate the imbalance correction. That is, the imbalance correction method of the present invention is a machine tool that includes a tool rotation axis and a tool rotated by the tool rotation axis, and processes the workpiece by linearly moving or rotating the tool relative to the workpiece and combining them with at least two or more drive axes of the machine tool, and is characterized in that a three-dimensional coordinate position is determined within the range in which the tool moves during machining of the workpiece, and the vibration imbalance is evaluated using a combination of each rotation speed and each coordinate position used during machining, and perform a certain weighting, and perform unbalance correction using a numerical optimization method so that the vibration is uniformly good at any position and rotation speed.
In addition, the machine tool of the present invention is a machine tool equipped with a tool rotation axis and a tool rotated by the tool rotation axis, and machines a workpiece by moving the tool relative to the workpiece using at least two or more drive axes of the machine tool, in which a three-dimensional or two-dimensional coordinate position is determined within the range in which the tool moves while machining the workpiece, vibration imbalance is evaluated and weighted using a combination of each rotation speed and each coordinate position used during machining, and the machine tool performs vibration imbalance correction using a numerical optimization method so that vibration is uniformly good at all positions and rotation speeds, and is characterized in being equipped with an automatic imbalance correction mechanism for performing the imbalance correction .
It is also possible to configure a similar correction method and machine tool for balancing vibrations when rotating a workpiece.

The present invention provides a technology that can correct imbalance so that it is uniformly good at any position and rotation speed while a workpiece is being machined by a machine tool. It also provides a machine tool that is equipped with an automatic imbalance correction mechanism to fully automate the correction of imbalance.

FIG. 1 is a diagram for explaining the known technology described in Non-Patent Document 1. FIG. 2 is a diagram showing an example of a machine tool equipped with a device as shown in FIG. 1 . FIG. 2 is a diagram showing another example of a machine tool equipped with a device such as that shown in FIG. 1 . 1 is a diagram for explaining how to three-dimensionally distribute coordinates for evaluating vibration in an imbalance correction method based on evaluation of vibration at three-dimensional positions according to an embodiment of the present invention; FIG. 1 is a flowchart showing one cycle of vibration measurement, which is a partial cycle of a method for correcting imbalance by evaluating vibration in a three-dimensional position according to an embodiment of the present invention. 1 is a flowchart showing a method for correcting imbalance by evaluating vibration in three-dimensional positions according to an embodiment of the present invention. 6 is a flowchart showing a generalized example of one cycle of the vibration measurement shown in FIG. 5 . 7 is a flowchart showing a generalized example of the unbalance correction method shown in FIG. 6. FIG. 13 is a diagram for explaining the correspondence relationship between a space of a correcting weight and a space of vibration evaluation.

First, in order to facilitate understanding of the present invention, the known technology described in the above-mentioned non-patent document 1 will be described with reference to FIG. 1. According to non-patent document 1, for example, the following can be considered. That is, assume a rotating machine as shown in FIG. 1. As shown in FIG. 1, in this rotating machine, the correction surfaces 11, 12, and 13 of the rotating body 10 have screw holes (not shown) so that screws (not shown) can be left as weights (not shown), there are waste parts (not shown in particular), the waste parts can be cut off, and the weights (not shown) can be moved and fixed. In FIG. 1, 16 is a tool or grindstone, and 17 and 18 are examples of acceleration sensors.

各要素は各センサの振動観測の結果である。軸方向にｎ箇所にセンサが配置されていて、振動を観測できるとする。ここでは、ある回転数Ｓ₁における振幅と位相の情報を有する複素数とする。このような観測はロックインアナライザ（たとえば、得られる振動計の信号に回転に同期した９０度位相の異なる正弦波をかけて直流成分だけを捉える）などの回転同期型のフィルタを用いて行われるとなお良い。 As described in Non-Patent Document 1, pages 103 to 104, the number of balance correction surfaces is m, and the number of vibration measurement points is n. The initial vibration A ₀ is measured. The following formula (1) is obtained.

Each element is the result of vibration observation by each sensor. Assume that sensors are arranged at n locations in the axial direction and vibration can be observed. Here, it is assumed that it is a complex number having amplitude and phase information at a certain rotation speed _S1 . It is even better if such observation is performed using a rotation-synchronous filter such as a lock-in analyzer (for example, by applying a sine wave with a phase difference of 90 degrees synchronized with the rotation to the obtained signal of the vibrometer to capture only the DC component).

よって、修正面１に試しおもりをつける効果を単位おもり当たりに換算した係数α₁は、以下の数式（３）により得られる。

ただしαi,jはi番目のセンサ位置、j修正面番号をあらわす。この手順を各修正面について繰り返しすべての係数を求める（各修正面の単位おもりが各センサに与える影響係数）。以下の数式（４）が得られる。

釣り合わせでは、初期振動Ａ₀を打ち消すように各修正面におもりＣ_j（大きさと位相を持つ複素数）をつければよく、次の数式（５）のように得られる。

ただし、次の数式（６Ａ）（６Ｂ）が成り立つ。

よく行われるのはｎ＝ｍ＝１またはｎ＝ｍ＝２である。ｎ＝ｍの場合には、次の数式（７）として求まる。

参考文献にあるとおり、ｎ＞ｍの場合には、最小二乗法として、次の数式（８）が成り立つ。

なお、数（９Ａ）は数（９Ｂ）の共役転置を表現しただけである。

また、影響係数α_iについて各修正面について繰り返しすべての係数を求める計算には、上述のように右辺がＡ_０との差をとりそのとき追加した試し錘で割る形式であることは必要なく、以下の数式（１０）のような形式でもよい。

この場合には、ある修正面に試し錘をつけて振動を評価したら、一つ前までにつけた試し錘を残したまま各修正面に錘を増やしたときの影響係数を計算するということになる。特に駄肉部分を削るような不釣合い修正面を使う場合には、一旦削り落とすと元に戻せないのでこのような形式となることがある。 Next, vibration _A1 observed by each sensor is measured when a test weight W1 ₍ a complex number having a phase and a magnitude) is added to the unbalance correction surface 1 and rotated at the same rotation speed. The following formula (2) is obtained.

Therefore, the coefficient α ₁ , which converts the effect of attaching a trial weight to the correction surface 1 into a unit weight, can be obtained by the following formula (3).

Here, αi,j represents the i-th sensor position and j-th correction plane number. This procedure is repeated for each correction plane to obtain all the coefficients (the coefficients of the influence of the unit weight of each correction plane on each sensor). The following formula (4) is obtained.

In balancing, weights C _j (complex numbers having magnitude and phase) are attached to each correction surface so as to cancel the initial vibration A ₀ , and this is obtained as shown in the following equation (5).

However, the following equations (6A) and (6B) hold.

What is often done is n = m = 1 or n = m = 2. When n = m, it is obtained as the following formula (7).

As described in the reference, when n>m, the following formula (8) holds true as the least squares method.

Note that number (9A) simply represents the conjugate transpose of number (9B).

In addition, the calculation for repeatedly finding all the coefficients of the influence coefficient _αi for each correction surface does not need to be in the form in which the right side takes the difference from _A0 and divides it by the test weight added at that time as described above, but may be in the form of the following formula (10).

In this case, a test weight is attached to a certain correction surface to evaluate the vibration, and then the influence coefficient is calculated when the weight is added to each correction surface while leaving the previous test weight in place. This format is sometimes used, especially when using an unbalance correction surface that removes excess material, because once it is removed it cannot be restored.

ここで、先ほどまでｎとしていた要素数は「振動測定箇所」の「回転数の個数」倍で、ｎ×ｋになる。
結果的には、α_０、…、α_ｍの要素数を拡張することにも繋がる。よって次の数式（１２）が成り立つ。

ただし、注意すべき点はＣの要素数ｍは拡張しない。
どんどん先述のｎ(要素数)⋙ mに近づいていく。手計算では面倒でも、このような計算をこなす不釣合い修正システムは多面多速度釣り合わせ対応と称され商品化されている（例えば、シグマ電子工業株式会社ＳＢ－７７０５Ｒなど）。逆にＣを置けば不釣合い修正で残る予測（各回転数ごと）も次の数式（１３）により可能である。

Usually, many field balancers (tools for evaluating and correcting imbalance on-site) state that the evaluation rotation speed should be constant, but
Here, when the rotation speed _S1 is changed and testing is performed at a plurality of rotation speeds _S1 , _S2 , _{..., Sk} , the number of elements n of A0 _, ..., _Am is expanded. In other words, each rotation speed is considered as the output of a different sensor.
This can be expressed as in the following equation (11), for example.

Here, the number of elements, which was previously n, is now n×k, which is the number of rotations of the vibration measurement points.
As a result, this also leads to an expansion of the number of elements of α ₀ , ..., α _m . Therefore, the following formula (12) holds.

However, it should be noted that the number of elements m of C is not expanded.
It gets closer and closer to the aforementioned n (number of elements) × m. Although it is troublesome to calculate by hand, imbalance correction systems that can handle such calculations are called multi-surface, multi-speed balancing systems and are commercially available (for example, Sigma Electronics Co., Ltd. SB-7705R). Conversely, if you place C, the remaining predictions (for each rotation speed) in imbalance correction can also be made using the following formula (13).

Usually, even in the case of a device that can handle multiple speeds as mentioned above, it is explained that the coordinates of the machine should be kept constant. This is based on the idea that if the unbalance of the rotating body is made zero, when it is used as a tool rotation mechanism, the excitation force, which is the force that generates vibration, will be zero, so no matter what coordinate the tool rotation device is placed on, the vibration will be zero. However, since balancing actually involves adjusting the sensor position to cancel out the vibration, it is natural that the excitation force is not made completely zero. This residual excitation force can create resonance when the machine coordinates are moved, increasing the vibration. Even if it is possible to make it zero at one coordinate, a situation may arise where the vibration increases when the coordinate is changed.
Some workers may express this as "balance changes depending on the tool coordinates," but in many cases, the unbalance of the rotor remains the same, but a change in coordinates causes the residual vibration to resonate more easily or less easily. Of course, in an actual elastic rotor, the unbalance can change depending on the rotation speed.

結果的には、次の数式（１５）

の計算から、α_０、…、α_ｍの要素数を拡張することにも繋がる。これにより先ほどまでｎとしていた要素数はｎ×ｋ×ｌと飛躍的に増加するが、電子計算器を用いれば容易に計算可能である。
回転数Ｓ_１ ，Ｓ_２ ，_…Ｓ_ｋでおよび機械の座標Ｐ_１，Ｐ_２，_…Ｐ_iは使用する範囲内で分布させる。特に座標は複数の送り軸および回転軸を使用する場合にはその範囲内で立体的に分布させる。
このようにとったとき、最小二乗法によって得られる修正の指示は、回転数Ｓ_１ ，Ｓ_２ ，_…Ｓ_ｋでおよび機械の座標Ｐ_１，Ｐ_２，_…Ｐ_iの範囲内で全体的に振動を小さく保つ指示に近い。
ここで，Ｐ_iとはＸ－Ｙ－Ｚの３軸を有する機械なら３次元，５軸を有する機械なら５次元の要素を有し得るベクトル変数である。 Therefore, by expanding the above idea, even when changing the machine coordinate _P1 and testing at multiple coordinates _P1 , _P2 , _... , _Pi , the number of elements n of A0 _, ..., _Am is expanded again. In other words, it is considered that not only the rotation speed but also the output of a different sensor is used for each coordinate.
This can be expressed as in the following equation (14), for example.

As a result, the following formula (15)

This calculation also leads to the expansion of the number of elements of α _{0 ,} ..., α _m . As a result, the number of elements, which was previously n, increases dramatically to n x k x l, but this can be easily calculated using an electronic calculator.
The rotational speeds _S1 , _S2 , _{... Sk} and the coordinates _P1 , _P2 , _{... Pi} of the machine are distributed within the range of use. In particular, the coordinates are distributed three-dimensionally within the range when a plurality of feed axes and rotary axes are used.
When taken in this way, the correction instructions obtained by the least squares method are close to _those which keep the vibrations small overall at the rotational speeds S ₁ , S ₂ , _{. . . Sk} and within the range of machine coordinates P ₁ , P ₂ , _{. .} . Pi.
Here, P _i is a vector variable that can have three-dimensional elements for a machine having three axes, XYZ, and five-dimensional elements for a machine having five axes.

In addition, even if there is no device such as a rotation-synchronous filter such as a lock-in analyzer (for example, a sine wave with a phase shift of 90 degrees synchronized with the rotation is applied to the obtained signal from the vibrometer to capture only the DC component), non-patent document 1 shows that the influence coefficient can be obtained by drawing a diagram when evaluating the case where test weights are attached to three phases that are not parallel to each other and the case where test weights are not attached (see pages 128 to 130 of non-patent document 1).

Next, we will describe a method for correcting imbalance by evaluating vibrations in three-dimensional positions according to an embodiment of the present invention, and a machine tool that can automate this method. First, consider a rotary motor device for a cutting tool or grinding wheel, as shown in Figure 1 above. This device has two built-in imbalance correction surfaces that can be manually adjusted, and one correction surface is provided on the tool side, making it possible to address imbalance with a total of three correction surfaces. Two accelerometers (sensors) are installed for balancing.

Figure 2 shows an example of a machine tool capable of automating the imbalance correction method according to an embodiment of the present invention, equipped with a device as shown in Figure 1. That is, as shown in Figure 2, this machine tool is equipped with mutually orthogonal X-axis and Z-axis, A-axis rotating about the X-axis, and C-axis rotating about the Z-axis, and has an X-feed motor 21, an A-rotation motor 22, a Z-feed motor 23, a C-rotation motor 24, a grindstone motor 25, and a tool (grindstone) 26, and is a machine tool for machining a workpiece W, and is equipped with a device as shown in Figure 1 at the location of the grindstone motor 25.

Fig. 3 is a diagram showing another example of a machine tool capable of automating the unbalance correction method according to the embodiment of the present invention, which is equipped with the device as shown in Fig. 1. That is, as shown in Fig. 3, this machine tool is equipped with mutually orthogonal X-axis, Y-axis, and Z-axis, and a rotating C-axis around the Z-axis, and has an X-feed device 31, a Z-feed device 32, a tool spindle 33, a tool 34, a work table 35, and a C-rotation device 36, and is a machine tool that processes a workpiece W with the tool 34, and is equipped with a device as shown in Fig. 1 at the tool spindle 33. Note that the Y-feed device is not shown. That is, here, a machine tool equipped with X-Y-Z as shown in Fig. 3 is considered. It is assumed that the C-axis coordinate is a unique coordinate during a certain machining process. For example, _P0 = (x, y, z) = (0, 0, 0), _P1 = (-200, 0, 0), _P2 = (0, -200, 0), _P3 = (-200, -200, 0), _P4 = (0, 0, -200), _P5 = (-200, 0, -200), _P6 = (-200, -200, -200). For the rotation speed, _S1 = 1000, _S2 = 2000.

4 is a diagram for explaining the three-dimensional distribution of coordinates for evaluating vibration in the method for correcting imbalance by evaluating vibration in three-dimensional positions according to an embodiment of the present invention. As shown in FIG. 4, three-dimensional means that the coordinates are distributed within the range to be used, not on a plane or a straight line. However, this does not apply when only one or two axes are used.
As shown in FIG. 4, the remaining axes (rotation axes) are also distributed, and the rotation speeds are also distributed.

Figure 5 is a flowchart showing one cycle of vibration measurement, which is a partial cycle of the method for correcting imbalance by evaluating the three-dimensional position of vibration according to an embodiment of the present invention. That is, as shown in Figure 5, in one cycle of vibration measurement 500, when one cycle is started (S501), i = 1 is set (S502), and it is determined whether i is 6 (coordinate number) or less (S503), and if it is 6 (coordinate number) or less (Yes in S503), it moves to coordinate Pi (S504). j = 1 is set (S505), and it is determined whether j is 2 (rotation number) or less (S506), and if it is 2 (rotation number) or less (Yes in S506), j = j + 1 is set (S507), and the number of rotations is changed to Sj (S508). Then, the processes from S506 to S508 are repeated so that vibration is evaluated with n sensors (S509). On the other hand, if j is not 2 (number of rotations) or less in S506 (No in S506), then i = i + 1 is set (S510) and the processes from S503 onwards are repeated. Also, if i is not 6 (number of coordinates) or less in S503 (No in S503), then this cycle ends (S511). This cycle of vibration evaluation results in a 3 x 6 x 2 (that is, n x (number of coordinate points l) x (number of rotations k)) vibration evaluation (information with magnitude and phase, where two sensors are counted as one). Changes in position and rotation speed, and vibration evaluation under each condition can be automatically performed by the machine tool's control device.

なお、修正面に試し錘をつけるときに、一々、一つ前の試し錘を除去すると記述したが、しない場合や出来ない場合には、影響係数の計算式を以下の数式（１７）のように変更する。

なおこの影響係数が厳密に有効なのは、各面への錘の追加と振動の大きさの関係が線形の場合に限る。ただ、最終の修正の時の錘の追加と試し錘が数十倍の差がなければ評価として有用である。以下の数式（１８）

と置き、εの絶対値が最小になるように、Ｃ_１， Ｃ_２， Ｃ_３を探す数値最小化問題として扱うことができる。その一解法として最小二乗法が適用できる。
以上を一般化すると、以下の図７と図８のようになる。 Fig. 6 is a flow chart showing an unbalance correction method by evaluation of vibration in a three-dimensional position according to an embodiment of the present invention. That is, as shown in Fig. 6, one cycle of vibration measurement shown in Fig. 5 is performed (S600), and initial vibration is measured without adding a correction test weight. Then, first, a test weight is added to the correction plane 1 (S601), and one cycle of vibration measurement is performed (S602). Next, a test weight is added to the correction plane 2 (S603), and one cycle of vibration measurement is performed (S604). At this time, the test weight added to the correction plane 1 (S602) is removed. Furthermore, a test weight is added to the correction plane 3 (S605), and one cycle of vibration measurement is performed (S606). At this time, the test weight added to the correction plane 2 (S603) is removed. The influence of the test weight is measured by the above processes from S601 to S606. After this, the optimal correction amount is calculated (S607), and the final correction is performed (S608). The imbalance is corrected by the processes of S607 and S608. Finally, one cycle of vibration measurement is performed (S609), which is a cycle for confirming the effect. At the time when one cycle of vibration measurement of S606 is performed, vibration evaluation (information having magnitude and phase) is obtained for 4 x 2 x 6 x 2 elements (4: 1 initial measurement + 3 measurements with test weights, 2: number of rotations, 6: number of coordinates, 2: number of sensors).
Incidentally, when a test weight is attached to each surface as shown in FIG. 6 to evaluate vibration, after the measurement of the influence of the test weight is completed, the influence of each surface on each element of vibration can be calculated as an influence coefficient using the following formula (16).

In addition, it has been described that when attaching a test weight to the correction surface, the previous test weight is removed each time. However, if this is not done or if it is not possible, the formula for calculating the influence coefficient is changed to the following formula (17).

This influence coefficient is strictly valid only when the relationship between the addition of weights to each surface and the magnitude of vibration is linear. However, it is useful as an evaluation if the difference between the addition of weights at the time of final correction and the trial weight is not several tens of times. The following formula (18)

Then, it can be treated as a numerical minimization problem of finding C ₁ , C ₂ , and C ₃ so that the absolute value of ε is minimized. The least squares method can be applied as one of the solving methods.
If the above is generalized, it becomes as shown in FIG. 7 and FIG. 8 below.

Figure 7 is a flow chart showing a generalized example of one cycle of vibration measurement shown in Figure 5. That is, as shown in Figure 7, in one cycle of vibration measurement 700, when one cycle is started (S701), i = 1 is set (S702), and it is determined whether i is l (number of coordinates) or less (S703), and if it is l (number of coordinates) or less (Yes in S703), it moves to coordinate Pi (S704). j = 1 is set (S705), and it is determined whether j is k (number of rotations) or less (S706), and if it is k (number of rotations) or less (Yes in S706), j = j + 1 is set (S707), and the number of rotations is changed to Sj (S708). Then, the processing from S706 to S708 is repeated so that vibration is evaluated with n sensors (S709). On the other hand, if j is not k (number of rotations) or less in S706 (No in S706), i = i + 1 is set (S710), and the processing from S703 onwards is repeated. Furthermore, if i is not equal to or less than l (number of coordinates) in S703 (No in S703), this cycle ends (S711). This cycle of vibration evaluation produces a vibration evaluation (information with magnitude and phase) of n x (number of coordinate points l) x (number of rotations k).

Figure 8 is a flow chart showing a generalized example of the unbalance correction method shown in Figure 6. That is, as shown in Figure 8, one cycle of vibration measurement shown in Figure 7 is performed (S800). Then, correction plane 1 is tried, a weight is added (S801), and one cycle of vibration measurement is performed (S802). Next, correction plane 2 is tried, a weight is added (S803), and one cycle of vibration measurement is performed (S804). This is repeated until correction plane m is tried, a weight is added (S805), and one cycle of vibration measurement is performed (S806). After this, the optimal correction amount is calculated (S807), and the final correction is performed (S808). Finally, one cycle of vibration measurement is performed (S809), which is a cycle to confirm the effect.

Fig. 9 is a diagram for explaining the correspondence between the space of the corrected weights and the space of the vibration evaluation. That is, up to this point, the influence coefficient _αi has been explicitly solved, but it is also possible to directly deal with the problem of searching for Ca that minimizes the magnitude of the vibration evaluation Aa by attaching a combination of weights Ca to each corrected surface and assuming that there is a certain function for the corrected weights and the vibration evaluation as shown in Fig. 9, as shown in the following formulas (19A) and (19B).

10 Rotating body, 11, 12, 13 Correcting surface, 16 Tool (grindstone), 17, 18 Acceleration sensor,
21 X feed motor, 22 A rotation motor, 23 Z feed motor, 24 C rotation motor, 25 grindstone motor, 26 tool (grindstone), W workpiece,
31 X-feed device, 32 Z-feed device, 33 Tool spindle, 34 Tool, 35 Work table, 36 C-rotation device

Claims (2)

1. A method for correcting imbalance by evaluating vibration in a machine tool including a tool rotation shaft and a tool rotated by the tool rotation shaft, the machine tool machining a workpiece by moving the tool relative to the workpiece using at least two or more drive shafts of the machine tool, comprising:
A method for correcting an imbalance by evaluating a three-dimensional position of vibration, characterized in that a three-dimensional or two-dimensional coordinate position is determined within the range in which the tool moves during machining of the workpiece, the vibration imbalance is evaluated and weighted using a combination of each rotation speed and each coordinate position used during machining, and the vibration imbalance is corrected using a numerical optimization method so that the vibration is uniformly good at all positions and rotation speeds. A machine tool including a tool rotation shaft and a tool rotated by the tool rotation shaft, the machine tool machining a workpiece by moving the tool relative to the workpiece using at least two or more drive shafts of the machine tool,
A machine tool that determines three-dimensional or two-dimensional coordinate positions within the range in which the tool moves while machining the workpiece, evaluates the vibration imbalance using a combination of each rotation speed and each coordinate position used during machining, assigns a certain weighting to it, and corrects the vibration imbalance using a numerical optimization method so that the vibration is uniformly good at all positions and rotation speeds , and is characterized by being equipped with an automatic imbalance correction mechanism for performing the imbalance correction .

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