JP2009101495A - Vibration suppressing apparatus - Google Patents

Vibration suppressing apparatus Download PDF

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JP2009101495A
JP2009101495A JP2007277865A JP2007277865A JP2009101495A JP 2009101495 A JP2009101495 A JP 2009101495A JP 2007277865 A JP2007277865 A JP 2007277865A JP 2007277865 A JP2007277865 A JP 2007277865A JP 2009101495 A JP2009101495 A JP 2009101495A
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vibration
chatter
rotation speed
frequency
value
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JP4777960B2 (en
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Hiroshi Inagaki
浩 稲垣
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Okuma Corp
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Okuma Corp
Okuma Machinery Works Ltd
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Priority to JP2007277865A priority Critical patent/JP4777960B2/en
Priority to US12/255,120 priority patent/US8014903B2/en
Priority to ITMI2008A001866A priority patent/IT1393057B1/en
Priority to DE102008052954.0A priority patent/DE102008052954B4/en
Priority to CN2008101749479A priority patent/CN101417398B/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration suppressing apparatus capable of obtaining an optimum rotational speed for effectively suppressing "chatter vibration". <P>SOLUTION: The vibration suppressing apparatus includes: vibration sensors 2a to 2c for detecting vibration acceleration in a time region of a rotary shaft 3 during rotation; a FFT arithmetic device 6 for calculating chatter vibration and the vibration acceleration of a frequency region in the chatter vibration; a storage device 9 for storing the vibration acceleration of the frequency region and the chatter vibration, etc, as processing information; an arithmetic device 7 for storing a maximum acceleration and the chatter vibration, etc, in the storage device 9 as new processing information, when the calculated maximum acceleration of the frequency region exceeds a prescribed threshold value, and calculating the optimum rotational speed capable of suppressing the chatter vibration based on the new processing information and the past processing information stored in the storage device 9; and an NC device 8 for rotating the rotary shaft 3 at the optimum rotational speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

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、たとえば回転可能な主軸にワークを支持させ、回転するワークに対して工具を送りながら、ワークの外周面等に切削加工を施す工作機械がある。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、特に問題となるのが自励振動である「再生型びびり振動」である。そして、該「再生型びびり振動」を抑制するためには、特許文献１及び２に開示されているように、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のびびり周波数を求め、固有振動数又はびびり周波数を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として加工を行え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 performs cutting on an outer peripheral surface of a workpiece while supporting the workpiece on a rotatable main shaft and feeding a tool to the rotating 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, “regenerative chatter vibration” which is self-excited vibration is particularly problematic. In order to suppress the “regenerative chatter vibration”, as disclosed in Patent Documents 1 and 2, the natural frequency of a system in which “chatter vibration” such as a tool or a workpiece occurs, or chatter during machining. It is known that the frequency may be obtained, and the natural frequency or chatter frequency may be multiplied by 60 and the value obtained by dividing by the number of tool blades and a predetermined integer may be used as the rotational speed.

尚、「びびり振動」が生じる系の固有振動数については、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求めることができる。また、加工中のびびり周波数については、特許文献２に記載されているように、工具やワークの近傍に音センサを配置し、加工中に該音センサが検出した振動周波数をもとに求めることができる。   Note that the natural frequency of a system in which “chatter vibration” occurs can be obtained by measuring the frequency by applying an impulse vibration to a tool or a workpiece, as described in Patent Document 1. Further, as described in Patent Document 2, a chatter frequency during machining is obtained based on a vibration frequency detected by a sound sensor disposed in the vicinity of a tool or a workpiece. Can do.

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、インパルス加振して固有振動数を求める方法を採用すると、高価なインパルス装置が必要となるため、コスト高になるという問題がある。また、特許文献１に記載の加振方法には高度な技術が必要となるにも拘わらず、「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、「びびり振動」を効果的に抑制可能な最適回転速度を得にくいし、実用性にも劣るといった問題もある。
一方、音センサを用いてびびり周波数を求める方法を採用したとしても、「回転音等の分析により算出されたびびり周波数」と「加工中の固有振動数」との間には差異があるため、最適回転速度を求めることができず、結果的に、加工面にびびりマークが残るといった問題がある。 However, when the method of obtaining the natural frequency by applying the impulse is employed, an expensive impulse device is required, which increases the cost. In addition, although the vibration method described in Patent Document 1 requires advanced technology, the “natural frequency measured before machining” and the “natural frequency during machining” do not necessarily match. In addition, there is a problem that it is difficult to obtain an optimum rotation speed capable of effectively suppressing “chatter vibration” and inferior in practicality.
On the other hand, even if the method of obtaining chatter frequency using a sound sensor is adopted, there is a difference between "frequency of chatter calculated by analysis of rotating sound" and "natural frequency during processing". There is a problem that the optimum rotation speed cannot be obtained, and as a result, a chatter mark remains 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、「びびり振動」を効果的に抑制可能な最適回転速度を求めることができる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 problem, and an object of the present invention is to provide a vibration suppressing device capable of obtaining an optimum rotation speed capable of effectively suppressing “chatter vibration”.

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の時間領域の振動を検出する検出手段と、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する第１演算手段と、周波数領域の振動、びびり振動数、及び回転軸回転速度を加工情報として記憶する記憶手段と、前記第１演算手段により算出された周波数領域の振動が所定の閾値を超えた場合に、その周波数領域の振動、びびり振動数、及びその時の回転軸回転速度を新たな加工情報として記憶手段に記憶するとともに、当該新たな加工情報と、前記記憶手段に記憶されている過去の加工情報とにもとづき、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第２演算手段と、前記第２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回転速度制御手段とを備えてい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、振動自体は勿論、振動に起因して回転軸に発生し、間接的に振動を検出できる物理的変化を含むものである。 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 suppression apparatus for suppressing vibrations, wherein a detection means for detecting vibration in the time domain of the rotating shaft during rotation, and a chatter frequency and the chatter frequency based on the vibration in the time domain detected by the detection means First calculation means for calculating vibration in the frequency domain at the frequency, storage means for storing frequency domain vibration, chatter vibration frequency, and rotating shaft rotation speed as machining information, and the frequency calculated by the first calculation means When the vibration in the region exceeds a predetermined threshold, the vibration in the frequency region, the chatter frequency, and the rotation speed at that time are stored in the storage means as new machining information. Based on the new machining information and past machining information stored in the storage means, second calculation means for calculating an optimum rotation speed of the rotating shaft capable of suppressing chatter vibration, and the second calculation means And a rotation speed control means for rotating the rotation shaft at the optimum rotation speed calculated by the above.
Note that “vibration” described in claim 1 refers to vibration acceleration, displacement due to vibration, sound pressure due to vibration, etc., as well as vibration itself, which occurs on the rotating shaft due to vibration, and indirectly detects vibration. It includes physical changes that can be made.

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、第２演算手段では、下記の演算式（１）〜（３）にもとづいて位相情報を算出するとともに、当該位相情報及び記憶手段に記憶されている過去の加工情報をもとに最適回転速度を算出す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） According to a second aspect of the present invention, in the first aspect of the invention, the second calculation means calculates phase information based on the following calculation formulas (1) to (3), and also stores the phase information and storage. The optimum rotational speed is calculated based on past machining information stored in the means.
k ′ value = 60 × chat vibration frequency / (number of tool blades × rotational axis rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3)

本発明によれば、実際に回転している回転軸に生じた「びびり振動」を検出し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」の増幅を確実に抑制することができ、加工面にびびりマークが残ったりしない。
また、周波数領域の振動が所定の閾値を超える度に、当該振動、びびり振動数、及び回転軸回転速度を加工情報として記憶手段に記憶しており、次回以降、振動が閾値を超えた場合には、記憶手段に記憶されている過去の加工情報を利用して最適回転速度を算出する。したがって、安定限界線図で述べるところの最も再生型びびり振動が生じない最適回転速度を容易に算出することができ、加工面の仕上げ精度を高品位に保つことができる。 According to the present invention, since the chatter vibration generated in the rotating shaft that is actually rotating is detected and the optimum rotation speed is calculated, a more accurate optimum rotation speed can be immediately calculated. Therefore, amplification of “chatter vibration” can be reliably suppressed, and no chatter mark remains on the processed surface.
In addition, every time the vibration in the frequency domain exceeds a predetermined threshold, the vibration, chatter frequency, and rotation shaft rotation speed are stored in the storage means as machining information. Uses the past processing information stored in the storage means to calculate the optimum rotation speed. Therefore, the optimum rotational speed at which the most regenerative chatter vibration does not occur as described in the stability limit diagram can be easily calculated, and the finishing accuracy of the processed surface can be maintained at a high quality.

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。
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を側方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。 Hereinafter, a vibration suppression device according to an embodiment of the present invention will be described with reference to the drawings.
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.

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（時間軸上の振動加速度を意味する）を検出するための振動センサ（検出手段）２ａ〜２ｃと、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５とからなる。   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. Vibration sensors (detection means) 2a to 2c for detecting vibration acceleration (meaning vibration acceleration on the time axis), and the rotational speed of the rotary shaft 3 based on the detected values by the vibration sensors 2a to 2c. And a control device 5 for controlling.

振動センサ２ａ〜２ｃは、図２及び図３に示す如く、回転軸ハウジング１の回転軸３近傍位置に取り付けられており、一の振動センサが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を検出する（たとえば、それぞれ直交するＸ軸、Ｙ軸、及びＺ軸方向への時間領域の振動加速度を検出する）ようになっている。   As shown in FIGS. 2 and 3, the vibration sensors 2a to 2c are attached to a position near the rotation shaft 3 of the rotation shaft housing 1, and one vibration sensor is a time domain in a direction perpendicular to the other vibration sensors. (For example, the vibration acceleration in the time domain in the X-axis, Y-axis, and Z-axis directions orthogonal to each other is detected).

一方、制御装置５は、振動センサ２ａ〜２ｃにより検出された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（第１演算手段）６と、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等の算出を行う演算装置（第２演算手段）７と、演算装置７で算出された算出値等を記憶する記憶装置（記憶手段）９と、回転軸ハウジング１での加工を制御するＮＣ装置（回転速度制御手段）８とを備えており、回転軸３の回転速度を後述の如く制御して、回転軸３に生じる「びびり振動」を抑制するようになっている。   On the other hand, the control device 5 is calculated by an FFT computing device (first computing means) 6 that performs analysis based on vibration acceleration in the time domain detected by the vibration sensors 2 a to 2 c and the FFT computing device 6. The calculation device (second calculation means) 7 that calculates the optimum rotation speed and the like based on the value, the storage device (storage means) 9 that stores the calculation value calculated by the calculation device 7, and the rotary shaft housing 1 And an NC device (rotational speed control means) 8 for controlling the machining of the rotary shaft 3, and controls the rotational speed of the rotary shaft 3 as described later to suppress “chatter vibration” generated on the rotary shaft 3. Yes.

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５のフローチャートをもとに説明する。
まず、ＦＦＴ演算装置６で、振動センサ２ａ〜２ｃにより回転軸３の回転中に常時検出される時間領域での振動加速度のフーリエ解析を行い（Ｓ１）、図４の４に示すような最大加速度（周波数領域の振動加速度）とその周波数（びびり振動数）とを算出する（Ｓ２）。
次に、演算装置７で、上記Ｓ２で算出された最大加速度と予め設定された所定の閾値とを比較し（Ｓ３）、閾値を超えた場合には、回転軸３に抑制すべき「びびり振動」が生じているとして、びびり振動数、工具刃数、及び回転軸３の回転速度から以下の演算式（１）〜（３）により、ｋ’値、ｋ値、及び位相情報を算出するとともに、当該ｋ’値、ｋ値、及び位相情報に加えて、上記Ｓ２で算出された最大加速度及びびびり振動数、さらには現時点での回転軸回転速度を新たな加工情報として記憶装置９へ記憶する（Ｓ４）。 Here, suppression control of “chatter vibration” in the control device 5 will be described based on the flowchart of FIG. 5.
First, the FFT arithmetic unit 6 performs Fourier analysis of vibration acceleration in the time domain that is always detected by the vibration sensors 2a to 2c during rotation of the rotating shaft 3 (S1), and the maximum acceleration as shown by 4 in FIG. (Vibration acceleration in the frequency domain) and its frequency (chatter frequency) are calculated (S2).
Next, the computing device 7 compares the maximum acceleration calculated in S2 above with a predetermined threshold value set in advance (S3). ”, The k ′ value, the k value, and the phase information are calculated from the chatter frequency, the number of tool blades, and the rotational speed of the rotary shaft 3 by the following arithmetic expressions (1) to (3). In addition to the k ′ value, k value, and phase information, the maximum acceleration and chatter frequency calculated in S2 and the current rotational speed of the rotating shaft are stored in the storage device 9 as new machining information. (S4).

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）
ここで、演算式（１）における「工具刃数」は、予め演算装置７に入力設定されているものとする。また、演算式（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。 k ′ value = 60 × chat vibration frequency / (number of tool blades × rotational axis rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3)
Here, it is assumed that the “number of tool blades” in the calculation formula (1) is input and set in the calculation device 7 in advance. Further, the rotation shaft rotation speed in the calculation formula (1) is the current rotation speed (before the optimum rotation speed).

さらに、記憶装置９に記憶されている加工情報のうち、前回閾値を超えた際の位相情報及び回転軸回転速度（過去の加工情報）と、前々回閾値を超えた際の位相情報及び回転軸回転速度（過去の加工情報）とを読み出し、以下の演算式（４）及び（５）により、最適回転速度を算出する（Ｓ５）。   Furthermore, among the machining information stored in the storage device 9, the phase information and rotational axis rotation speed (past machining information) when the previous threshold is exceeded, and the phase information and rotational axis rotation when the previous threshold is exceeded The speed (past machining information) is read out, and the optimum rotation speed is calculated by the following arithmetic expressions (4) and (5) (S5).

速度変化量＝（１−前々回の位相情報）×（前々回の回転軸回転速度−前回の回転軸回
転速度）／（前回の位相情報−前々回の位相情報） ・・・（４）
最適回転速度＝前々回の回転軸回転速度−速度変化量 ・・・（５）
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の回転速度を変更し、「びびり振動」の増幅の防止、すなわち抑制を行う（Ｓ６）。
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。 Speed change amount = (1−phase information of previous rotation) × (rotation speed of previous rotation axis−rotation axis of previous rotation)
Rotation speed) / (Previous phase information-Previous phase information) (4)
Optimum rotation speed = Previous rotation axis rotation speed−Speed change amount (5)
Then, the rotation speed of the rotary shaft 3 is changed by the NC device 8 so that the calculated optimum rotation speed is obtained, and amplification of “chatter vibration” is prevented, ie, suppressed (S6).
As described above, the suppression control of “chatter vibration” in the control device 5 is performed.

尚、回転軸３の回転開始後、初めて閾値を超える最大加速度が検出された場合、及び閾値を超える最大加速度の検出が二度目であった場合には、上記演算式（４）を用いることができない。したがって、この場合にはＳ３の後、演算式（３）で得られた位相情報と設定定数とを比較し、位相情報が設定定数以上であれば、演算式（６）によりｋ１値を算出する一方、位相情報が設定定数未満であれば、演算式（７）によりｋ１値を算出する。
ｋ１値＝ｋ値＋１ ・・・（６）
ｋ１値＝ｋ値 ・・・（７）
ここで、設定定数としては、通常０．５を設定すれば回転速度の変化量を最小とすることができる。ただし、回転速度の変化割合が小さい場合、回転速度を変更する方向によっては安定限界線図でいう切削下限を下回ってしまい、再生型びびり振動を生じる可能性があるため、その下限を設定定数として位相情報と比較すればよい。その場合、設定定数としては０．７５を採用することが望ましい。 Note that when the maximum acceleration exceeding the threshold is detected for the first time after the rotation of the rotating shaft 3 is detected, and when the maximum acceleration exceeding the threshold is detected for the second time, the above equation (4) may be used. Can not. Therefore, in this case, after S3, the phase information obtained by the calculation formula (3) is compared with the set constant, and if the phase information is equal to or greater than the set constant, the k1 value is calculated by the calculation formula (6). On the other hand, if the phase information is less than the set constant, the k1 value is calculated by the equation (7).
k1 value = k value + 1 (6)
k1 value = k value (7)
Here, if the setting constant is normally set to 0.5, the amount of change in the rotational speed can be minimized. However, if the change rate of the rotation speed is small, depending on the direction of changing the rotation speed, it may fall below the lower cutting limit in the stability limit diagram and may cause regenerative chatter vibration. What is necessary is just to compare with phase information. In that case, it is desirable to adopt 0.75 as the setting constant.

そして、上記演算式（６）又は（７）で得られたｋ１値を用い、以下の演算式（８）により最適回転速度を算出することができ、該最適回転速度となるように回転軸３の回転速度を変更すればよい。
最適回転速度＝６０×びびり振動数／（工具刃数×ｋ１値） ・・・（８） Then, using the k1 value obtained by the above equation (6) or (7), the optimum rotation speed can be calculated by the following equation (8), and the rotation shaft 3 is set so as to be the optimum rotation speed. What is necessary is just to change the rotational speed of.
Optimum rotation speed = 60 x chatter frequency / (number of tool blades x k1 value) (8)

上述したような振動制御装置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の回転速度を最適回転速度に変更するようになっている。このように、実際に回転している回転軸３に生じた「びびり振動」を検出し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」の増幅を確実に抑制することができ、加工面にびびりマークが残ったりしない。   According to the vibration control device 10 as described above, the vibration sensors 2a to 2c, the FFT calculation device 6, and the calculation device 7 monitor “chatter vibration” generated during the rotation of the rotary shaft 3 in real time. When the occurrence of “vibration” is detected, the optimum rotational speed is immediately calculated by the above-described arithmetic expressions (1) to (5), and the rotational speed of the rotary shaft 3 is changed to the optimum rotational speed. As described above, since the “chatter vibration” generated in the rotating shaft 3 actually rotating is detected and the optimum rotation speed is calculated, a more accurate optimum rotation speed can be immediately calculated. Therefore, amplification of “chatter vibration” can be reliably suppressed, and no chatter mark remains on the processed surface.

また、周波数領域の振動加速度の最大加速度が閾値を超える度に、当該最大加速度とその周波数（びびり振動数）、回転軸回転速度に加え、演算式（１）〜（３）により算出されるｋ’値、ｋ値、及び位相情報を新たな加工情報として記憶装置９に記憶し、次回以降、最大加速度が閾値を超えた場合には、記憶装置９に記憶されている過去の加工情報を利用して最適回転速度を算出するようになっている。したがって、安定限界線図で述べるところの最も再生型びびり振動が生じない最適回転速度を容易に算出することができ、加工面の仕上げ精度を高品位に保つことができる。   Further, every time the maximum acceleration of the vibration acceleration in the frequency domain exceeds the threshold value, k is calculated by the arithmetic expressions (1) to (3) in addition to the maximum acceleration, the frequency (chatter frequency), and the rotational speed of the rotating shaft. 'Value, k value, and phase information are stored in the storage device 9 as new processing information, and when the maximum acceleration exceeds the threshold value from the next time, the past processing information stored in the storage device 9 is used. Thus, the optimum rotation speed is calculated. Therefore, the optimum rotational speed at which the most regenerative chatter vibration does not occur as described in the stability limit diagram can be easily calculated, and the finishing accuracy of the processed surface can be maintained at a high quality.

さらに、記憶装置９に十分な加工情報が記憶されていない１度目及び２度目の「びびり振動」検出時には、位相情報を設定情報と比較し、その比較結果に応じて変更したｋ１値をもとに夫々最適回転速度を算出する。したがって、「びびり振動」を短時間で抑制することができ、加工面の仕上げ精度の向上、工具摩耗の抑制、工具欠損の防止を期待することができる。   Further, when the first and second “chatter vibrations” are detected when sufficient machining information is not stored in the storage device 9, the phase information is compared with the setting information, and the k1 value changed according to the comparison result is used as a basis. The optimum rotation speed is calculated for each. Therefore, “chatter vibration” can be suppressed in a short time, and improvement of the finished surface finishing accuracy, suppression of tool wear, and prevention of tool chipping can be expected.

なお、本発明に係る振動抑制装置は、上記実施形態に記載の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。   Note that the vibration suppression device according to the present invention is not limited to the aspect described in the above embodiment, and the configuration relating to the vibration suppression control in the detection means, the control device, and the control device is not limited to that of the present invention. As long as it does not deviate from the meaning, it can change suitably as needed.

たとえば、演算式（１）〜（８）に示すようなｋ’値、ｋ値、位相情報、速度変化量等やこれらの関係は、工作機械の種類に応じて適宜調査し決定することで、精度をさらに向上させることができる。
また、速度変化量の算出にあたり、演算式（４）では定数「１」から前々回の位相情報を減算するようにしているが、該定数は、理論上「１」となるるものの、「１．０５」等「１」からややずれた値を用いて速度変化量を求めるようにしてもよい。 For example, the k ′ value, the k value, the phase information, the speed change amount, and the like as shown in the arithmetic expressions (1) to (8) are appropriately investigated and determined depending on the type of the machine tool. The accuracy can be further improved.
Further, in calculating the speed change amount, the previous phase information is subtracted from the constant “1” in the arithmetic expression (4). Although the constant is theoretically “1”, “1. The speed change amount may be obtained using a value slightly deviated from “1” such as “05”.

さらに、上記実施形態では、記憶装置にｋ’値、ｋ値、及び位相情報に加えて、上記Ｓ２で算出された最大加速度及びびびり振動数、さらには現時点での回転軸回転速度を加工情報として記憶するようにしているが、ｋ’値、ｋ値、及び位相情報については記憶せず、演算式（４）による演算を行う都度、加工情報をもとに算出するよう構成することも可能である。
さらにまた、上記実施形態では、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う際、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となる複数（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、「びびり振動」の抑制効果の更なる向上を図ってもよい。 Furthermore, in the above embodiment, in addition to the k ′ value, the k value, and the phase information in the storage device, the maximum acceleration and chatter frequency calculated in S2 above, and the current rotational speed of the rotating shaft are used as machining information. However, the k ′ value, the k value, and the phase information are not stored, but can be calculated based on the processing information every time the calculation according to the calculation formula (4) is performed. is there.
Furthermore, in the above embodiment, when performing Fourier analysis of the vibration acceleration in the time domain detected by the detection means, the suppression control of “chatter vibration” is performed using a waveform in which the vibration acceleration in the frequency domain shows the maximum value. However, the optimum rotational speed is calculated using a plurality of (for example, three) waveforms having higher frequency vibration acceleration values in the frequency domain, and the effect of suppressing “chatter vibration” is further improved. Improvements may be made.

またさらに、上記実施形態では、振動センサにより回転軸の振動加速度を検出するよう構成しているが、振動による回転軸の変位や音圧を検出し、当該変位や音圧にもとづいて最適回転速度を算出するように構成することも可能である。
加えて、上記実施形態では、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）の振動を検出し、最適回転速度を算出するように構成してもよいし、工具を回転させるマシニングセンタに限らず、ワークを回転させる旋盤等といった工作機械にも適用可能である。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 vibration acceleration of the rotating shaft is detected by the vibration sensor. However, the displacement and sound pressure of the rotating shaft due to vibration are detected, and the optimum rotational speed is determined based on the displacement and sound pressure. It is also possible to configure so as to calculate.
In addition, in the above-described embodiment, the vibration on the rotation axis of the machine tool is detected. However, the vibration on the non-rotating side (fixed side) may be detected and the optimum rotation speed may be calculated. The present invention can be applied not only to a machining center that rotates a tool but also to a machine tool such as a lathe that rotates a workpiece. 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方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. 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. びびり振動の抑制制御に係るフローチャート図である。It is a flowchart figure which concerns on 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・・演算装置、８・・ＮＣ装置、９・・記憶装置、１０・・振動抑制装置。   ··· Rotating shaft housing, 2a, 2b, 2c ·· Vibration sensor, 3 ·· Rotating shaft, 5 ·· Control device, 6 ·· FFT computing device, 7 ·· Calculating device, 8 ·· NC device, 9 · -Memory device, 10 ... Vibration suppression device.

Claims (2)

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の時間領域の振動を検出する検出手段と、
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する第１演算手段と、
周波数領域の振動、びびり振動数、及び回転軸回転速度を加工情報として記憶する記憶手段と、
前記第１演算手段により算出された周波数領域の振動が所定の閾値を超えた場合に、その周波数領域の振動、びびり振動数、及びその時の回転軸回転速度を新たな加工情報として記憶手段に記憶するとともに、当該新たな加工情報と、前記記憶手段に記憶されている過去の加工情報とにもとづき、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第２演算手段と、
前記第２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。 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,
Detecting means for detecting vibration in the time domain of the rotating shaft during rotation;
First operation means for calculating chatter frequency and frequency domain vibration at the chatter frequency based on the time domain vibration detected by the detection means;
Storage means for storing frequency domain vibration, chatter frequency, and rotational axis rotation speed as machining information;
When the vibration in the frequency domain calculated by the first calculation means exceeds a predetermined threshold, the vibration in the frequency domain, the chatter frequency, and the rotation speed at that time are stored in the storage means as new machining information. And, based on the new machining information and past machining information stored in the storage means, a second calculation means for calculating an optimum rotation speed of the rotating shaft capable of suppressing chatter vibration,
And a rotation speed control means for rotating the rotation shaft at the optimum rotation speed calculated by the second calculation means. 第２演算手段では、下記の演算式（１）〜（３）にもとづいて位相情報を算出するとともに、当該位相情報及び記憶手段に記憶されている過去の加工情報をもとに最適回転速度を算出することを特徴とする請求項１に記載の振動抑制装置。
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） The second calculation means calculates phase information based on the following calculation formulas (1) to (3), and calculates the optimum rotation speed based on the phase information and past machining information stored in the storage means. The vibration suppression device according to claim 1, wherein the vibration suppression device is calculated.
k ′ value = 60 × chat vibration frequency / (number of tool blades × rotational axis rotation speed) (1)
k value = integer part of k ′ value (2)
Phase information = k ′ value−k value (3)
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