JP4433422B2 - Vibration suppression device - Google Patents

Vibration suppression device Download PDF

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JP4433422B2
JP4433422B2 JP2007138166A JP2007138166A JP4433422B2 JP 4433422 B2 JP4433422 B2 JP 4433422B2 JP 2007138166 A JP2007138166 A JP 2007138166A JP 2007138166 A JP2007138166 A JP 2007138166A JP 4433422 B2 JP4433422 B2 JP 4433422B2
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vibration
value
frequency
rotation speed
chatter
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JP2008290188A (en
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教和 鈴木
英二 社本
浩 稲垣
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Nagoya University NUC
Okuma Corp
Tokai National Higher Education and Research System NUC
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Nagoya University NUC
Okuma Corp
Tokai National Higher Education and Research System NUC
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Priority to JP2007138166A priority Critical patent/JP4433422B2/en
Priority to US12/107,191 priority patent/US8256590B2/en
Priority to IT000871A priority patent/ITMI20080871A1/en
Priority to CN2008101090391A priority patent/CN101310921B/en
Priority to DE200810024773 priority patent/DE102008024773A1/en
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Description

本発明は、工具又はワークを回転させながら加工を行う工作機械において、加工中に発生する振動、特に再生型びびり振動を抑制するための振動抑制装置に関するものである。   The present invention relates to a vibration suppressing device for suppressing vibration generated during machining, particularly regenerative chatter vibration, in a machine tool that performs machining while rotating a tool or a workpiece.

従来より、たとえば回転可能な主軸にワークを支持させ、ワークに対して工具を送りながら、ワークに加工を施すといった工作機械がある。該工作機械においては、切削加工における切り込み量を必要以上に大きくすると、加工中に所謂「びびり振動」が発生して、加工面の仕上げ精度を悪化させてしまうという問題がある。このとき、特に問題となるのは自励振動である「再生型びびり振動」であり、該「再生型びびり振動」を抑制するためには、特許文献１、２に記載されているように、加工を行うにあたって、工具やワーク等の「びびり振動」が生じる系の固有振動数や加工中におけるびびり振動数を求め、固有振動数又はびびり振動数を６０倍して工具刃数及び所定の整数で除した値を回転速度（以下、該方法にて算出された回転速度を安定回転速度とする）とすればよいことが知られている。   2. Description of the Related Art Conventionally, for example, there is a machine tool that supports a workpiece on a rotatable spindle and processes the workpiece while feeding a tool to the workpiece. In the machine tool, if the depth of cut in the cutting process is increased more than necessary, there is a problem that so-called “chatter vibration” occurs during the process, and the finished accuracy of the processed surface is deteriorated. At this time, a particularly problematic problem is “regenerative chatter vibration” which is self-excited vibration. In order to suppress the “regenerative chatter vibration”, as described in Patent Documents 1 and 2, When performing machining, find the natural frequency of the system that generates chatter vibrations such as tools and workpieces, chatter frequency during machining, multiply the natural frequency or chatter frequency by 60, and the number of tool blades and a predetermined integer. It is known that a value obtained by dividing by the rotation speed may be used as a rotation speed (hereinafter, the rotation speed calculated by the method is referred to as a stable rotation speed).

そして、「びびり振動」が生じる系の固有振動数を求めるためには、特許文献１に記載されているように、工具やワークをインパルス加振して振動数を測定することにより「固有振動数」を求めるといった方法が知られている。また、加工中におけるびびり振動数を求めるためには、特許文献２に記載されているように、回転中の工具やワークの近傍に音センサを配置して、加工中に音センサにて検出された振動周波数にもとづいて「びびり振動数」を求めるといった方法がある。   Then, in order to obtain the natural frequency of a system in which “chatter vibration” occurs, as described in Patent Document 1, a tool or a work is subjected to impulse vibration to measure the vibration frequency. Is known. Further, in order to obtain the chatter frequency during machining, as described in Patent Document 2, a sound sensor is arranged in the vicinity of a rotating tool or workpiece and detected by the sound sensor during machining. There is a method of obtaining “chatter frequency” based on the vibration frequency.

特開２００３−３４０６２７号公報JP 2003-340627 A 特表２００１−５１７５５７号公報JP-T-2001-517557

しかしながら、上記特許文献１の方法で「固有振動数」を求めるとなると、高価なインパルス装置を必要とするため、コスト高になるという問題がある。また、特許文献１の加振方法は、高度な技術を要するにも拘わらず、加工前に測定した「固有振動数」と加工中の「固有振動数」とは必ずしも一致しないため正確な最適回転速度を得にくいといったように、実用性に劣るという問題もある。
一方、上記特許文献２の方法では、音センサによる回転音等を分析して「びびり振動数」を得ようとしているものの、回転音等の分析により算出した「びびり振動数」と最適回転速度における「びびり振動数」との間には差異があるため、上記特許文献１の方法同様、正確な最適回転速度を得ることは難しい。すなわち、回転音等から「びびり振動数」を算出する場合、「びびり振動」に相当する振動周波数が検出された後、さらに数回の加工や測定を実施した上で漸近的に「びびり振動数」を求めることになるため、「びびり振動」が検出されてから最適回転速度を算出するまでに時間を要してしまい、結果的に加工面にびびりによるマークが残ってしまうという問題がある。 However, when the “natural frequency” is obtained by the method of Patent Document 1, an expensive impulse device is required, which increases the cost. In addition, although the vibration method disclosed in Patent Document 1 requires a high level of technology, the “natural frequency” measured before machining does not necessarily match the “natural frequency” during machining, so that an accurate optimum rotational speed is obtained. There is also a problem that it is inferior in practicality, such as difficult to obtain.
On the other hand, in the method of Patent Document 2 described above, a “chatter frequency” is obtained by analyzing a rotating sound or the like by a sound sensor. Since there is a difference with “chatter frequency”, it is difficult to obtain an accurate optimum rotational speed, as in the method of Patent Document 1. In other words, when calculating the “chatter frequency” from rotating sound, etc., after the vibration frequency corresponding to “chatter vibration” is detected, after further processing and measurement several times, asymptotically, “chatter frequency” Therefore, it takes time until the optimum rotation speed is calculated after the “chatter vibration” is detected, and as a result, there is a problem that marks due to chatter remain on the processed surface.

そこで、本発明は、上記問題に鑑みなされたものであって、正確な最適回転速度を求めることができる上、びびり振動が生じてから最適回転速度を算出するまでの時間を短縮可能な振動抑制装置を提供しようとするものである。   Therefore, the present invention has been made in view of the above problems, and is capable of obtaining an accurate optimum rotation speed and suppressing vibrations that can reduce the time from the occurrence of chatter vibration until the optimum rotation speed is calculated. The device is to be provided.

上記目的を達成するために、本発明のうち請求項１に記載の発明は、工具又はワークを回転させるための回転軸を備えた工作機械において、前記回転軸を回転させた際に生じるびびり振動を抑制するための振動抑制装置であって、
回転中の前記回転軸による時間領域の振動を検出するための検出手段と、該検出手段により検出された時間領域の振動にもとづいて、びびり振動数及び該びびり振動数における周波数領域の振動を算出し、算出した前記周波数領域の振動が所定の閾値を超えた場合、びびり振動数を６０倍して工具刃数及び所定の整数で除した安定回転速度を求めるとともに、少なくとも後述の式（１）〜（３）により算出されるｋ値及び位相情報にもとづいて係数を定め、当該係数と前記安定回転速度とからびびり振動を抑制可能な前記回転軸の最適回転速度を算出するための演算手段と、該演算手段により算出された最適回転速度にて前記回転軸を回転させるための回転速度制御手段とを備えていることを特徴とする。
ｋ’値＝６０×びびり振動数／（工具刃数×回転軸回転速度） ・・・ （１）
ｋ値＝ｋ’値の整数部 ・・・ （２）
位相情報＝ｋ’値−ｋ値 ・・・ （３）
請求項２に記載の発明は、請求項１に記載の発明において、演算手段は、上記式（１）〜（３）にて算出されるｋ値及び位相情報を用いた演算式により、使用する係数を算出して定めることを特徴とする。
請求項３に記載の発明は、請求項２に記載の発明において、演算手段に、上記式（１）〜（３）にて算出されるｋ値及び位相情報に対応づけて複数の係数を予め記憶させておき、前記演算手段は、演算手段に、上記式（１）〜（３）にて算出されるｋ値及び位相情報に対応づけて複数の係数を予め記憶させておき、前記演算手段は、算出されたｋ値及び位相情報にもとづき、使用する係数を選択して定めることを特徴とする。
尚、請求項１に記載の「振動」とは、振動加速度、振動による変位、及び振動による音圧等を含むものである。 In order to achieve the above object, the invention according to claim 1 of the present invention is a chatter vibration generated when a rotating shaft for rotating a tool or a workpiece is rotated in the machine tool. A vibration suppressing device for suppressing vibration,
Detection means for detecting vibration in the time domain due to the rotating shaft during rotation, and calculation of chatter frequency and frequency domain vibration at the chatter frequency based on the vibration in the time domain detected by the detection means When the calculated vibration in the frequency region exceeds a predetermined threshold, the chatter frequency is multiplied by 60 to obtain a stable rotational speed divided by the number of tool blades and a predetermined integer, and at least the following formula (1) Calculating means for determining a coefficient based on the k value and the phase information calculated by (3), and calculating an optimum rotation speed of the rotating shaft capable of suppressing chatter vibration from the coefficient and the stable rotation speed ; And a rotation speed control means for rotating the rotation shaft at the optimum rotation speed calculated by the calculation means.
k ′ value = 60 × chat vibration frequency / (number of tool blades × rotating shaft rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3)
According to a second aspect of the present invention, in the first aspect of the present invention, the computing means is used according to an arithmetic expression using the k value and phase information calculated by the above formulas (1) to (3). The coefficient is calculated and determined .
According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of coefficients are preliminarily associated with the k value and phase information calculated by the above formulas (1) to (3). The calculation unit stores a plurality of coefficients in advance in association with the k value and the phase information calculated by the above formulas (1) to (3), and the calculation unit stores the plurality of coefficients in advance. is convex-out to the calculated k values and phase information, characterized in that determined by selecting the coefficients to be used.
The “vibration” described in claim 1 includes vibration acceleration, displacement due to vibration, sound pressure due to vibration, and the like.

本発明によれば、回転中の回転軸による時間領域の振動を検出するための検出手段と、該検出手段により検出された時間領域の振動にもとづいて、びびり振動数及び該びびり振動数における周波数領域の振動加速度を算出するとともに、算出した周波数領域の振動が所定の閾値を超えた場合、びびり振動数を６０倍して工具刃数及び所定の整数で除した安定回転速度を求めるとともに、少なくとも後述の式（１）〜（３）により算出されるｋ値及び位相情報にもとづいて係数を定め、当該係数と安定回転速度とからびびり振動を抑制可能な回転軸の最適回転速度を算出するための演算手段と、該演算手段により算出された最適回転速度にて回転軸を回転させるための回転速度制御手段とを備えており、実際に回転している回転軸に生じる「びびり振動」にもとづいて最適回転速度を算出するため、より正確な最適回転速度を直ちに算出することができるとともに、算出した最適回転速度を直ちに回転軸の回転にいかすことができる。したがって、回転軸に生じる「びびり振動」を効果的に抑制することができ、加工面の仕上げ精度を高品位に保つことができる、工具摩耗の抑制、工具欠損の防止等といった効果を奏することができる。 According to the present invention, the detection means for detecting vibration in the time domain due to the rotating rotating shaft, and the chatter frequency and the frequency at the chatter frequency based on the vibration in the time domain detected by the detection means. When the vibration acceleration of the region is calculated, and when the vibration of the calculated frequency region exceeds a predetermined threshold value, the chatter frequency is multiplied by 60 to obtain the stable rotation speed divided by the number of tool blades and a predetermined integer, and at least To determine a coefficient based on the k value and phase information calculated by equations (1) to (3) described later, and to calculate the optimum rotational speed of the rotating shaft capable of suppressing chatter vibration from the coefficient and the stable rotational speed. And a rotation speed control means for rotating the rotation shaft at the optimum rotation speed calculated by the calculation means. Ri for calculating the optimum rotational speed on the basis of the oscillation ", it is possible to immediately calculate a more accurate optimum rotating speed, it is possible to utilize the rotation of the rotating immediately axis the calculated optimum rotational speed. Therefore, “chatter vibration” generated on the rotating shaft can be effectively suppressed, the finishing accuracy of the machined surface can be maintained at a high quality, tool wear can be suppressed, and tool loss can be prevented. it can.

以下、本発明の一実施形態となる振動抑制装置について、図面をもとに説明する。   Hereinafter, a vibration suppressing device according to an embodiment of the present invention will be described with reference to the drawings.

図１は、振動抑制装置１０のブロック構成を示した説明図である。図２は、振動抑制の対象となる回転軸ハウジング１を側面から示した説明図であり、図３は、回転軸ハウジング１を軸方向から示した説明図である。
振動抑制装置１０は、回転軸ハウジング１にＣ軸周りで回転可能に備えられた回転軸３に生じる「びびり振動」を抑制するためのものであって、回転中の回転軸３に生じる時間領域の振動加速度を検出するための振動センサ（検出手段）２ａ〜２ｃと、該振動センサ２ａ〜２ｃによる検出値をもとにして回転軸３の回転速度を制御する制御装置（演算手段、及び回転速度制御手段）５とを備えてなる。 FIG. 1 is an explanatory diagram showing a block configuration of the vibration suppressing device 10. FIG. 2 is an explanatory view showing the rotary shaft housing 1 to be subjected to vibration suppression from the side, and FIG. 3 is an explanatory view showing the rotary shaft housing 1 from the axial direction.
The vibration suppressing device 10 is for suppressing “chatter vibration” generated in the rotating shaft 3 provided in the rotating shaft housing 1 so as to be rotatable around the C axis, and is a time region generated in the rotating rotating shaft 3. Sensor (detection means) 2a to 2c for detecting the vibration acceleration of the motor, and a control device (calculation means and rotation) for controlling the rotational speed of the rotary shaft 3 based on the detection values by the vibration sensors 2a to 2c. Speed control means) 5.

振動センサ２ａ〜２ｃは、図２及び３に示す如く回転軸ハウジング１に取り付けられており、一の振動センサは、他の振動センサに対して直角方向への時間領域の振動加速度（時間軸上の振動加速度を意味する）を検出するようになっている（たとえば、振動センサ２ａ〜２ｃにて、それぞれ直交するＸ軸、Ｙ軸、Ｚ軸方向での時間領域の振動加速度を検出するようにする）。   The vibration sensors 2a to 2c are attached to the rotary shaft housing 1 as shown in FIGS. 2 and 3, and one vibration sensor is a time domain vibration acceleration (on the time axis) in a direction perpendicular to the other vibration sensors. (For example, the vibration sensors 2a to 2c detect vibration accelerations in the time domain in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, respectively). To do).

一方、制御装置５は、振動センサ２ａ〜２ｃから検出される時間領域の振動加速度をもとにした解析を行うＦＦＴ演算装置６と、該ＦＦＴ演算装置６にて算出された値にもとづいて最適回転速度の算出等を行うパラメータ演算装置７と、回転軸ハウジング１における加工を制御するＮＣ装置８とを備えており、ＦＦＴ演算装置６における後述の如き解析、及び回転軸３の回転速度のモニタリングを行っている。   On the other hand, the control device 5 is optimal based on the FFT calculation device 6 that performs analysis based on vibration acceleration in the time domain detected from the vibration sensors 2a to 2c, and the value calculated by the FFT calculation device 6. A parameter calculation device 7 for calculating the rotation speed and the like and an NC device 8 for controlling machining in the rotary shaft housing 1 are provided. Analysis as described later in the FFT calculation device 6 and monitoring of the rotation speed of the rotary shaft 3 are provided. It is carried out.

ここで、制御装置５における「びびり振動」の抑制制御について、図４〜図６をもとに説明する。図４は、時間領域の振動加速度のフーリエ解析結果の一例を示した説明図であり、図５は、最適回転速度の演算に必要な係数とｋ値、位相の関係の一例を示した説明図である。また、図６は、「びびり振動」の抑制制御について示したフローチャート図である。
まず、ＦＦＴ演算装置６では、回転中に常時検出される振動センサ２ａ〜２ｃにおける時間領域の振動加速度のフーリエ解析を行い（Ｓ１）、図４に示されるような、回転軸３の周波数（びびり振動数）と、該周波数における回転軸３の周波数領域の振動加速度（周波数軸上の振動加速度を意味する）とを算出する（Ｓ２）。尚、上記時間領域の振動加速度のフーリエ解析を行うと、周波数と周波数領域の振動加速度との関係を示した図４のような波形が複数パターン取得される。そのため、本実施形態では、周波数領域の振動加速度の値が最大となる波形を用いて、以下の制御を行う。
次に、パラメータ演算装置７では、上記ＦＦＴ演算装置６において算出された周波数領域の振動加速度と予め設定されている所定の閾値との比較を行い（Ｓ３）、算出された周波数領域の振動加速度が所定の閾値を超えた場合（たとえば、図４における周波数領域の振動加速度値４が検出された場合）には、回転軸３に抑制すべき「びびり振動」が生じているとして、以下の演算式（１）〜（５）により最適回転速度の演算を行う（Ｓ４）。そして、算出された最適回転速度となるように、ＮＣ装置８にて回転軸３の回転速度を制御して（Ｓ５）、「びびり振動」の増幅の防止、すなわち抑制を行う。
以上のようにして、制御装置５における「びびり振動」の抑制制御は行われる。

ｋ’値＝６０×びびり振動数／（工具刃数×回転軸回転速度） ・・・ （１）
ｋ値＝ｋ’値の整数部 ・・・ （２）
位相情報＝ｋ’値−ｋ値 ・・・ （３）
係数＝ａ−ｂ×ｋ値＋ｃ×位相情報 ・・・ （４）
最適回転速度＝係数×安定回転速度 ・・・ （５）
ここで、式（１）における「工具刃数」は、予めパラメータ演算装置７に設定されているものとする。また、式（１）における回転軸回転速度とは、現在（最適回転速度とする前）の回転速度である。さらに、式（５）における安定回転速度とは、上記背景技術に記載の方法にて算出された回転速度であり、該算出に際して「びびり振動数」はフーリエ解析により得られた値を用いるものとする。 Here, suppression control of “chatter vibration” in the control device 5 will be described with reference to FIGS. FIG. 4 is an explanatory diagram showing an example of the Fourier analysis result of vibration acceleration in the time domain, and FIG. 5 is an explanatory diagram showing an example of the relationship between the coefficient necessary for calculating the optimum rotational speed, the k value, and the phase. It is. FIG. 6 is a flowchart showing the control for suppressing “chatter vibration”.
First, the FFT processing unit 6 performs Fourier analysis of vibration acceleration in the time domain in the vibration sensors 2a to 2c that are constantly detected during rotation (S1), and the frequency (chatter) of the rotating shaft 3 as shown in FIG. Frequency) and vibration acceleration in the frequency domain of the rotating shaft 3 at the frequency (meaning vibration acceleration on the frequency axis) are calculated (S2). When Fourier analysis of the vibration acceleration in the time domain is performed, a plurality of waveforms as shown in FIG. 4 showing the relationship between the frequency and the vibration acceleration in the frequency domain are acquired. Therefore, in the present embodiment, the following control is performed using a waveform that maximizes the vibration acceleration value in the frequency domain.
Next, the parameter computing device 7 compares the vibration acceleration in the frequency domain calculated in the FFT computing device 6 with a predetermined threshold value set in advance (S3), and the calculated vibration acceleration in the frequency domain is obtained. When a predetermined threshold value is exceeded (for example, when the vibration acceleration value 4 in the frequency domain in FIG. 4 is detected), it is assumed that “chatter vibration” to be suppressed occurs on the rotating shaft 3 and the following arithmetic expression The optimum rotational speed is calculated according to (1) to (5) (S4). Then, the rotation speed of the rotary shaft 3 is controlled by the NC device 8 so as to obtain the calculated optimum rotation speed (S5), and amplification of “chatter vibration” is prevented, that is, suppressed.
As described above, the suppression control of “chatter vibration” in the control device 5 is performed.

k ′ value = 60 × chat vibration frequency / (number of tool blades × rotating shaft rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3)
Coefficient = a−b × k value + c × phase information (4)
Optimal rotation speed = coefficient x stable rotation speed (5)
Here, it is assumed that the “number of tool blades” in Equation (1) is set in the parameter calculation device 7 in advance. Further, the rotation shaft rotation speed in the equation (1) is the current rotation speed (before the optimum rotation speed). Further, the stable rotational speed in the equation (5) is a rotational speed calculated by the method described in the background art, and the “chatter frequency” uses a value obtained by Fourier analysis in the calculation. To do.

また、式（４）における定数ａ、ｂ、ｃの決定について説明する。
該定数ａ、ｂ、ｃは、回転軸３の回転速度と「びびり振動数」との関係等といった種々の条件にもとづいて作成される安定限界線図から決定される。たとえば、種々の回転速度にてテスト加工を実施し、加工中に検出される時間領域の振動加速度のフーリエ解析を行って回転軸の周波数（びびり振動数）と該周波数における周波数領域の振動加速度とを算出する。ここで、加工中における周波数領域の振動加速度は、回転速度の変化に応じて周期的に増減するものであり、該周波数領域の振動加速度が最小値となる回転速度が求めるべき最適回転速度となる。そこで、各回転速度における位相情報、ｋ値、及び安定回転速度等を上記演算式にて求め、各要素（位相情報やｋ値）と、周波数領域の振動加速度が最小値となる回転速度を安定回転速度にて除した値（すなわち、係数）との関係を、図５に示す如く、求める。そして、図５に示す関係から、種々の解析手法を用いて上述の係数演算式（式（４））の定数ａ、ｂ、ｃを決定する（たとえば、ａ＝０．９７１、ｂ＝０．００３、ｃ＝０．０４５等）。 The determination of the constants a, b, and c in the equation (4) will be described.
The constants a, b, and c are determined from a stability limit diagram created based on various conditions such as the relationship between the rotational speed of the rotary shaft 3 and “chatter frequency”. For example, test machining is performed at various rotational speeds, Fourier analysis of vibration acceleration in the time domain detected during machining is performed, and the frequency of the rotation axis (chatter frequency) and vibration acceleration in the frequency domain at the frequency are determined. Is calculated. Here, the vibration acceleration in the frequency domain during machining is periodically increased or decreased according to the change in the rotation speed, and the rotation speed at which the vibration acceleration in the frequency domain is the minimum value is the optimum rotation speed to be obtained. . Therefore, the phase information, k value, stable rotation speed, etc. at each rotation speed are obtained by the above formula, and each element (phase information and k value) and the rotation speed at which the vibration acceleration in the frequency domain is the minimum value are stabilized. The relationship with the value divided by the rotational speed (that is, the coefficient) is obtained as shown in FIG. Then, from the relationship shown in FIG. 5, the constants a, b, and c of the above-described coefficient arithmetic expression (formula (4)) are determined using various analysis techniques (for example, a = 0.971, b = 0. 003, c = 0.045, etc.).

以上のような振動抑制に係る制御を行う振動制御装置１０によれば、振動センサ２ａ〜２ｃ、ＦＦＴ演算装置６、及びパラメータ演算装置７により回転軸３の回転中に生じる「びびり振動」をリアルタイムでモニタリングしており、「びびり振動」の発生が検出されると、上記演算式（１）〜（５）により直ちに最適回転速度を算出して、回転軸３の回転速度を該最適回転速度として「びびり振動」の増幅を抑制する。すなわち、実際に回転している回転軸３に生じた「びびり振動」にもとづいて最適回転速度を算出するため、より正確な最適回転速度を直ちに算出することができる。したがって、「びびり振動」を効果的に抑制することができ、加工面の仕上げ精度を高品位に保つことができる、工具摩耗の抑制、工具欠損の防止等といった効果を奏することができる。   According to the vibration control device 10 that performs the control related to vibration suppression as described above, “vibration vibration” generated during the rotation of the rotary shaft 3 by the vibration sensors 2a to 2c, the FFT calculation device 6, and the parameter calculation device 7 is detected in real time. When the occurrence of “chatter vibration” is detected, the optimum rotational speed is immediately calculated by the above arithmetic expressions (1) to (5), and the rotational speed of the rotary shaft 3 is set as the optimum rotational speed. Suppresses “chatter vibration” amplification. That is, since the optimum rotation speed is calculated based on “chatter vibration” generated in the rotating shaft 3 that is actually rotating, a more accurate optimum rotation speed can be immediately calculated. Therefore, the “chatter vibration” can be effectively suppressed, the finishing accuracy of the machined surface can be kept high, and effects such as suppression of tool wear and prevention of tool chipping can be achieved.

なお、本発明の振動抑制装置に係る構成は、上記実施の形態に記載した態様に何ら限定されるものではなく、検出手段、制御装置、及び制御装置における振動抑制の制御等に係る構成を、本発明の趣旨を逸脱しない範囲で、必要に応じて適宜変更することができる。   The configuration related to the vibration suppression device of the present invention is not limited to the mode described in the above embodiment, and the configuration related to vibration suppression control in the detection means, the control device, and the control device, The present invention can be changed as needed without departing from the spirit of the present invention.

たとえば、式（４）及び図５に示すような、位相情報、ｋ値、及び係数の関係は、工作機械の種類に応じて適宜調査し、決定するようにすることで精度をさらに向上することができる。つまり、係数を算出するにあたっては、上記実施形態に記載の式（４）に何ら限定されることはない。
また、上記実施形態では、係数を式（４）により算出して求める構成としているが、予め複数の係数値を、ｋ値及び位相情報に対応させた状態で制御装置に記憶させておき、算出されたｋ値及び位相情報に応じて係数を選択し決定するような構成とする（式（４）を省略する）ことも可能である。
さらに、検出手段にて検出される時間領域の振動加速度のフーリエ解析を行った際、上記実施形態では、周波数領域の振動加速度が最大値を示す波形を使用して、「びびり振動」の抑制に係る制御を行うようにしているが、周波数領域の振動加速度の値が上位の複数（たとえば、３つ）の波形を用いて最適回転速度を算出するようにして、「びびり振動」の抑制効果の更なる向上を図ってもよい。 For example, the accuracy of the relationship between the phase information, the k value, and the coefficient as shown in Expression (4) and FIG. 5 is further improved by appropriately investigating and determining according to the type of machine tool. Can do. That is, the calculation of the coefficient is not limited to the equation (4) described in the above embodiment.
In the above-described embodiment, the coefficient is calculated and calculated by Expression (4). However, a plurality of coefficient values are stored in the control device in advance in a state corresponding to the k value and the phase information, and the calculation is performed. It is also possible to adopt a configuration in which a coefficient is selected and determined in accordance with the k value and phase information (the expression (4) is omitted).
Furthermore, when Fourier analysis of the vibration acceleration in the time domain detected by the detection means is performed, in the above embodiment, the waveform having the maximum vibration acceleration in the frequency domain is used to suppress “chatter vibration”. Although such control is performed, the optimum rotational speed is calculated using a plurality of waveforms (for example, three) having higher values of vibration acceleration in the frequency domain, so that the effect of suppressing “chatter vibration” can be reduced. Further improvements may be made.

さらにまた、上記実施形態では、検出手段により回転軸の振動加速度を検出し、検出された振動加速度にもとづいて最適回転速度を算出するといった構成としているが、検出手段によって振動による変位や音圧を検出し、検出された変位や音圧に基づいて最適回転速度を算出するように構成してもよい。
加えて、上記実施形態では、工具を回転させる所謂マシニングセンタ等の工作機械の回転軸における振動を検出する構成としているが、回転しない側（固定側）であるワーク又はその近傍の振動を検出するようにしても良い。更には、旋盤などワークを回転させる工作機械にも適用可能であり、その場合には回転軸であるワークを保持する主軸側の振動を検出したり、固定側である工具の振動を検出したりすることができる。尚、検出手段の設置位置や設置数等を、工作機械の種類、大きさ等に応じて適宜変更してもよいことは言うまでもない。 Furthermore, in the above embodiment, the detection means detects the vibration acceleration of the rotating shaft, and calculates the optimum rotation speed based on the detected vibration acceleration. However, the detection means detects the displacement and sound pressure due to vibration. It may be configured to detect and calculate the optimum rotational speed based on the detected displacement and sound pressure.
In addition, in the above-described embodiment, the vibration is detected in the rotating shaft of a machine tool such as a so-called machining center that rotates the tool. However, the vibration on the non-rotating side (fixed side) or the vicinity thereof is detected. Anyway. Furthermore, it can also be applied to a machine tool that rotates a workpiece such as a lathe. In that case, it detects vibrations on the spindle side that holds the workpiece that is the rotation axis, or detects vibrations on the tool that is on the fixed side. can do. Needless to say, the installation position, the number of installations, and the like of the detection means may be appropriately changed according to the type and size of the machine tool.

振動抑制装置のブロック構成を示した説明図である。It is explanatory drawing which showed the block structure of the vibration suppression apparatus. 振動抑制の対象となる回転軸ハウジングを側面から示した説明図である。It is explanatory drawing which showed the rotating shaft housing used as the object of vibration suppression from the side surface. 回転軸ハウジングを軸方向から示した説明図である。It is explanatory drawing which showed the rotating shaft housing from the axial direction. 時間領域の振動加速度のフーリエ解析結果の一例を示した説明図である。It is explanatory drawing which showed an example of the Fourier-analysis result of the vibration acceleration of a time domain. 最適回転速度の演算に必要な係数とｋ値、位相の関係の一例を示した説明図である。It is explanatory drawing which showed an example of the relationship between the coefficient required for the calculation of the optimum rotation speed, the k value, and the phase. 「びびり振動」の抑制制御について示したフローチャート図である。It is the flowchart figure shown about suppression control of "chatter vibration".

符号の説明Explanation of symbols

１・・回転軸ハウジング、２ａ、２ｂ、２ｃ・・振動センサ、３・・回転軸、５・・制御装置、６・・ＦＦＴ演算装置、７・・パラメータ演算装置、８・・ＮＣ装置、１０・・振動抑制装置。   1 ··· Rotating shaft housing, 2a, 2b, 2c ·· Vibration sensor, 3 ··· Rotating shaft, 5 ·· Control device, 6 ·· FFT computing device, 7 ·· Parameter computing device, 8 ·· NC device, 10 ..Vibration suppression devices

Claims (3)

工具又はワークを回転させるための回転軸を備えた工作機械において、前記回転軸を回転させた際に生じるびびり振動を抑制するための振動抑制装置であって、
回転中の前記回転軸による時間領域の振動を検出するための検出手段と、該検出手段により検出された時間領域の振動にもとづいて、びびり振動数及び該びびり振動数における周波数領域の振動を算出し、算出した前記周波数領域の振動が所定の閾値を超えた場合、びびり振動数を６０倍して工具刃数及び所定の整数で除した安定回転速度を求めるとともに、少なくとも後述の式（１）〜（３）により算出されるｋ値及び位相情報にもとづいて係数を定め、当該係数と前記安定回転速度とからびびり振動を抑制可能な前記回転軸の最適回転速度を算出するための演算手段と、該演算手段により算出された最適回転速度にて前記回転軸を回転させるための回転速度制御手段とを備えていることを特徴とする振動抑制装置。
ｋ’値＝６０×びびり振動数／（工具刃数×回転軸回転速度） ・・・ （１）
ｋ値＝ｋ’値の整数部 ・・・ （２）
位相情報＝ｋ’値−ｋ値 ・・・ （３） In a machine tool provided with a rotating shaft for rotating a tool or a workpiece, a vibration suppressing device for suppressing chatter vibration generated when the rotating shaft is rotated,
Detection means for detecting vibration in the time domain due to the rotating shaft during rotation, and calculation of vibration frequency and vibration in the frequency domain at the chatter frequency based on the vibration in the time domain detected by the detection means When the calculated vibration in the frequency region exceeds a predetermined threshold, the chatter frequency is multiplied by 60 to obtain a stable rotational speed divided by the number of tool blades and a predetermined integer, and at least the following formula (1) Calculating means for determining a coefficient based on the k value and the phase information calculated by (3), and calculating an optimum rotation speed of the rotating shaft capable of suppressing chatter vibration from the coefficient and the stable rotation speed ; And a rotation speed control means for rotating the rotation shaft at the optimum rotation speed calculated by the calculation means.
k ′ value = 60 × chat vibration frequency / (number of tool blades × rotating shaft rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3) 演算手段は、上記式（１）〜（３）にて算出されるｋ値及び位相情報を用いた演算式により、使用する係数を算出して定めることを特徴とする請求項１に記載の振動抑制装置。 2. The vibration according to claim 1, wherein the calculation means calculates and determines a coefficient to be used by an arithmetic expression using the k value and the phase information calculated by the expressions (1) to (3). Suppression device. 演算手段に、上記式（１）〜（３）にて算出されるｋ値及び位相情報に対応づけて複数の係数を予め記憶させておき、前記演算手段は、算出されたｋ値及び位相情報にもとづき、使用する係数を選択して定めることを特徴とする請求項１に記載の振動抑制装置。 The computing means stores a plurality of coefficients in advance in association with the k value and phase information calculated by the above formulas (1) to (3), and the computing means calculates the calculated k value and phase information. even-out convex, the vibration suppression apparatus according to claim 1, characterized in that determined by selecting the coefficients to be used.
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IT000871A ITMI20080871A1 (en) 2007-05-24 2008-05-14 DEVICE AND METHOD OF VIBRATION ELIMINATION FOR MACHINE TOOL
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