JP2008290194A - Vibration suppressing apparatus of machine tool - Google Patents

Vibration suppressing apparatus of machine tool Download PDF

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JP2008290194A
JP2008290194A JP2007138375A JP2007138375A JP2008290194A JP 2008290194 A JP2008290194 A JP 2008290194A JP 2007138375 A JP2007138375 A JP 2007138375A JP 2007138375 A JP2007138375 A JP 2007138375A JP 2008290194 A JP2008290194 A JP 2008290194A
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vibration
value
rotation speed
calculated
optimum
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JP4582661B2 (en
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Norikazu Suzuki
教和 鈴木
Eiji Shamoto
英二 社本
Hiroshi Inagaki
浩 稲垣
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Nagoya University NUC
Okuma Corp
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Nagoya University NUC
Okuma Corp
Okuma Machinery Works Ltd
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Priority to JP2007138375A priority Critical patent/JP4582661B2/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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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • B23Q17/0971—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining by measuring mechanical vibrations of parts of the machine
    • B23Q17/0976—Detection or control of chatter

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Automatic Control Of Machine Tools (AREA)
  • Auxiliary Devices For Machine Tools (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress chatter vibration in a short time. <P>SOLUTION: The Fourier analysis for the acceleration of the chatter vibration is carried out in S1, and the maximum acceleration and its frequency are calculated in S2. Next, the maximum acceleration is compared with a preset specified threshold value in S3. When the maximum acceleration exceeds the threshold value, a k value and the information about a phase are calculated in S4 from the chatter frequency, the number of the cutting edges of a tool, and the rotational speed of a rotary shaft. Next, the information about the phase is compared with a preset constant in S5. When the information about the phase is larger than the set constant, a k1 value is calculated in S6 based on a changing expression (1). On the other hand, when the information about the phase is smaller than the set constant, the k1 value is calculated in S7 based on a changing expression (2). Then, the optimum rotational speed for minimizing the change of the rotational speed is calculated in S8 from the chatter frequency, the number of the cutting edges of the tool, and the k1 value. <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 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、工具とワークとの間に生じる自励振動である「再生型びびり振動」である。この再生型びびり振動（以下単に「びびり振動」という。）については、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 main shaft 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, the “regenerative chatter vibration” which is a self-excited vibration generated between the tool and the workpiece is particularly problematic. With respect to this regenerative chatter vibration (hereinafter simply referred to as “chatter vibration”), as described in Patent Documents 1 and 2, the natural frequency of a system in which chatter vibration of a tool or a workpiece occurs when machining is performed. Further, it is known that the chatter frequency during machining is obtained, and the value obtained by dividing the natural frequency or chatter frequency by 60 times and dividing by the number of tool blades and a predetermined integer is used.

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、上記対策は、回転速度を減少させる方向であるため、回転速度の変化量が大きい場合にはびびり振動の抑制に時間が掛かり、加工面にびびり痕が残ってしまうという問題があった。   However, since the above countermeasure is in the direction of decreasing the rotational speed, it takes time to suppress chatter vibration when the amount of change in the rotational speed is large, and there is a problem that chatter marks 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、びびり振動が生じた際にはその抑制に係る時間が最小となる最適回転速度を瞬時に求めることができ、びびり振動を短時間で効果的に抑制可能な工作機械の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 when chatter vibration occurs, the optimum rotation speed that minimizes the time required for suppressing the vibration can be obtained instantaneously. It is an object of the present invention to provide a machine tool vibration suppressing device that can be effectively suppressed by the above.

上記目的を達成するために、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、回転中の回転軸の時間領域で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基づいて、びびり振動数及びそのびびり振動数における周波数領域の振動を算出すると共に、算出した周波数領域の振動が所定の閾値を超えた場合、所定のパラメータに基づき、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演算手段と、その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回転速度制御手段と、を備え、演算手段は、最適回転速度を算出する際に、所定の条件に基づいて所定のパラメータを変更して回転速度の変化量が最小となるように最適回転速度を算出することを特徴とするものである。   In order to achieve the above object, the invention according to claim 1 is a machine tool having a rotating shaft for rotating a tool or a workpiece, in order to suppress chatter vibration generated when the rotating shaft is rotated. A vibration detecting device for detecting vibration in a time domain of a rotating rotating shaft, a chatter frequency and a frequency at the chatter frequency based on the vibration in the time domain detected by the detection unit. Calculation means for calculating the vibration of the region and, when the calculated vibration of the frequency region exceeds a predetermined threshold, calculating the optimum rotation speed of the rotating shaft capable of suppressing chatter vibration based on a predetermined parameter, and the calculation Rotation speed control means for rotating the rotary shaft at the optimum rotation speed calculated by the means, and the calculation means is predetermined based on a predetermined condition when calculating the optimum rotation speed. It is characterized in that the variation amount of the rotation speed by changing the parameters for calculating an optimum rotation speed to minimize.

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、所定のパラメータとなる下記の演算式（１）〜（４）に基づいて最適回転速度の演算を行うものであり、演算式（３）に基づいて算出した位相情報を所定の設定定数と比較し、その比較結果に基づいて演算式（４）のｋ値を変更するようにしたものである。
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）
最適回転速度＝６０×びびり振動数／（工具刃数×ｋ値）・・・（４） According to a second aspect of the present invention, in the first aspect of the present invention, the calculating means calculates the optimum rotational speed based on the following calculation formulas (1) to (4) that are predetermined parameters. Yes, the phase information calculated based on the arithmetic expression (3) is compared with a predetermined set constant, and the k value of the arithmetic expression (4) is changed based on the comparison result.
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)
Optimal rotation speed = 60 x chatter frequency / (number of tool blades x k value) (4)

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、演算手段は、位相情報が所定の設定定数である０．５以上の場合には、演算式（４）のｋ値に１を加算して最適回転速度を演算するようにしたものである。
請求項４に記載の発明は、請求項２に記載の発明において、演算手段は、位相情報が所定の設定定数である０．７５以上の場合には、演算式（４）のｋ値に１を加算して最適回転速度を演算するようにしたものである。
請求項５に記載の発明は、請求項２に記載の発明において、演算手段は、演算式（４）のｋ値に対して、ｋの場合とｋ＋１の場合との２つの最適回転速度を夫々算出し、その２つの最適回転速度と現在の回転速度との差が小さい方の回転速度を選択することで、回転速度の変化量が最小となる最適回転速度を算出するようにしたものである。
尚、請求項１における「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。 According to a third aspect of the present invention, in the second aspect of the present invention, when the phase information is 0.5 or more, which is a predetermined setting constant, the calculation means sets the k value of the calculation formula (4) to 1 Is added to calculate the optimum rotational speed.
According to a fourth aspect of the present invention, in the second aspect of the present invention, when the phase information is equal to or greater than 0.75 which is a predetermined setting constant, the calculation means sets the k value of the calculation formula (4) to 1 Is added to calculate the optimum rotational speed.
According to a fifth aspect of the present invention, in the second aspect of the present invention, the computing means has two optimum rotational speeds for k and k + 1, respectively, for the k value of the arithmetic expression (4). By calculating and selecting the rotation speed with the smaller difference between the two optimum rotation speeds and the current rotation speed, the optimum rotation speed that minimizes the amount of change in the rotation speed is calculated. .
The term “vibration” as used in claim 1 refers to a physical that can be detected on a rotating shaft indirectly due to vibration, as well as vibration itself, such as vibration acceleration, displacement due to vibration, and sound pressure due to vibration. Change.

本発明によれば、実際に回転している回転軸に生じるびびり振動に基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共に、算出した最適回転速度を直ちに回転軸の回転に活かすことができる。特に、演算手段は、回転速度の変化量が最小となるように所定のパラメータを変更して最適回転速度を算出するので、びびり振動が短時間で抑制可能となる。従って、加工面の仕上げ精度を高品位に保つことができ、工具摩耗の抑制、工具欠損の防止も期待できる。
According to the present invention, since the optimum rotation speed is calculated based on chatter vibration generated in the rotating shaft that is actually rotating, it is possible to immediately calculate a more accurate optimum rotation speed and to calculate the calculated optimum rotation speed. Immediately, it can be used to rotate the rotating shaft. In particular, since the calculation means calculates the optimum rotation speed by changing a predetermined parameter so that the amount of change in the rotation speed is minimized, chatter vibration can be suppressed in a short time. Therefore, the finishing accuracy of the machined surface can be maintained at a high quality, and it can be expected to suppress the tool wear and prevent the tool from being lost.

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 suppression 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 vibration in the time domain generated in the rotating rotating shaft 3. Vibration sensors (detection means) 2a to 2c for detecting acceleration, and a control device (calculation means and rotation speed control) for controlling the rotation speed of the rotary shaft 3 based on the detection values by the vibration sensors 2a to 2c. 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基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.

以下、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のフローチャートに基づいて説明する。
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の４に示すような最大加速度とその周波数（びびり振動数）とを算出する（Ｓ２）。
次に、パラメータ演算装置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、Ｓ４で、びびり振動数、工具刃数、回転軸３の回転速度から以下の演算式（１）〜（３）により、ｋ値及び位相情報を算出する。 Hereinafter, the chatter vibration suppression control in the control device 5 will be described based on the flowchart of FIG. 5.
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 maximum acceleration and its frequency (chatter) as shown in 4 of FIG. Frequency) is calculated (S2).
Next, the parameter calculation device 7 compares the maximum acceleration calculated in S2 and a predetermined threshold value set in advance (S3). If the threshold value is exceeded, chatter vibration to be suppressed on the rotating shaft 3 is detected. In S4, 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).

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、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 set in the parameter 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).

次に、Ｓ５において、演算式（３）で得られた位相情報と設定定数とを比較する。ここで、位相情報が設定定数以上であれば、Ｓ６で、変更式（１）に基づいてｋ１値を算出する。一方、位相情報が設定定数未満であれば、Ｓ７で、変更式（２）に基づいてｋ１値を算出する。
ｋ１値＝ｋ値＋１・・・変更式（１）
ｋ１値＝ｋ値・・・変更式（２）
なお、設定定数は、通常は０．５を設定すれば回転速度の変化量が最小となる。但し、回転速度の変化割合が小さい場合は、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、再生びびりを生じる可能性があるので、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、設定定数は０．７５を選択するのが望ましい。 Next, in S5, the phase information obtained by the arithmetic expression (3) is compared with the set constant. If the phase information is greater than or equal to the set constant, the k1 value is calculated based on the change equation (1) in S6. On the other hand, if the phase information is less than the set constant, the k1 value is calculated based on the change equation (2) in S7.
k1 value = k value + 1... change formula (1)
k1 value = k value... change formula (2)
Note that the amount of change in the rotational speed is minimized if the set constant is normally set to 0.5. However, when 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 cause regenerative chatter. Compare with information. In that case, it is desirable to select 0.75 as the setting constant.

次に、Ｓ８では、びびり振動数、工具刃数、Ｓ６，７で得られたｋ１値から、以下の演算式（４）に基づいて最適回転速度の演算を行う。
最適回転速度＝６０×びびり振動数／（工具刃数×ｋ１値）・・・（４）
そして、Ｓ９で、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て、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。 Next, in S8, the optimum rotational speed is calculated from the chatter frequency, the number of tool blades, and the k1 value obtained in S6 and 7, based on the following calculation formula (4).
Optimal rotation speed = 60 x chatter frequency / (number of tool blades x k1 value) (4)
In S9, the rotation speed of the rotary shaft 3 is changed by the NC device 8 so as to obtain the calculated optimum rotation speed, and chatter vibration amplification is prevented, that is, suppressed.
As described above, chatter vibration suppression control in the control device 5 is performed.

このように、上記形態の振動制御装置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）〜（４）及び変更式（１）（２）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基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。特に、パラメータ演算装置７は、位相情報を設定定数と比較し、その比較結果に応じて変更したパラメータで夫々最適回転速度を算出するので、びびり振動が短時間で抑制可能となる。従って、加工面の仕上げ精度を高品位に保つことができ、工具摩耗の抑制、工具欠損の防止も期待できる。   Thus, according to the vibration control device 10 of the above embodiment, chatter vibration generated during the rotation of the rotary shaft 3 is monitored in real time by the vibration sensors 2a to 2c, the FFT calculation device 6, and the parameter calculation device 7. When the occurrence of chatter vibration is detected, the optimum rotational speed is immediately calculated by the arithmetic expressions (1) to (4) and the modified expressions (1) and (2), and the rotational speed of the rotary shaft 3 is determined as the optimum rotational speed. As a suppression of 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. In particular, the parameter calculation device 7 compares the phase information with the set constant and calculates the optimum rotation speed with the parameter changed according to the comparison result, so that chatter vibration can be suppressed in a short time. Therefore, the finishing accuracy of the machined surface can be maintained at a high quality, and it can be expected to suppress the tool wear and prevent the tool from being lost.

図６は、本発明を採用しない従来の振動抑制装置を採用した場合、図７は、本発明の振動抑制装置を採用した場合の夫々のびびり周波数（びびり振動数）の抑制効果を示すグラフである。図６の場合は、回転速度が６８００ｍｉｎ−１から６２５０ｍｉｎ−１と大きく変化するため、びびり抑制に時間を要するのに対し、図７の場合では、回転速度が６８００ｍｉｎ−１から７０００ｍｉｎ−１に素早く変化して最適回転速度に達し、最大加速度Ｇが図６のタイミングよりも早く減少してびびり振動を短時間で抑制できていることがわかる。 FIG. 6 is a graph showing the effect of suppressing each chatter frequency (chatter frequency) when the conventional vibration suppression device not employing the present invention is employed, and FIG. is there. In the case of FIG. 6, since the rotational speed changes greatly from 6800 min −1 to 6250 min −1, it takes time to suppress chatter, whereas in the case of FIG. 7, the rotational speed quickly increases from 6800 min −1 to 7000 min −1 . It turns out that the optimum rotational speed is reached, the maximum acceleration G decreases earlier than the timing of FIG. 6, and chatter vibration can be suppressed in a short time.

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 appropriate without departing from the spirit of the present invention.

たとえば、演算式（１）〜（４）や変更式（１）（２）に示すような位相情報、ｋ値、設定定数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、決定するようにすることで精度をさらに向上させることができる。
また、上記ｋ１値から計算される最適回転速度について、Ｓ５からＳ８の処理に代えて、演算式（４）において、ｋ値とｋ値＋１とから夫々２つの最適回転速度を算出し、その２つの最適回転速度と現在の回転速度との差から回転速度変化量の割合が小さい方の最適回転速度を選択して、ＮＣ装置８にて回転軸３の回転速度を変更し、びびり振動の抑制を行うようにしてもよい。
さらに、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った際、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 phase information, the k value, the setting constant, etc. as shown in the arithmetic expressions (1) to (4) and the changing expressions (1) and (2) and the relationship thereof are appropriately investigated according to the type of the machine tool. By making the determination, the accuracy can be further improved.
Further, regarding the optimum rotation speed calculated from the k1 value, instead of the processing from S5 to S8, two optimum rotation speeds are calculated from the k value and the k value + 1 in the arithmetic expression (4), respectively. The optimum rotational speed with the smaller rate of change in rotational speed is selected from the difference between the two optimal rotational speeds and the current rotational speed, and the rotational speed of the rotary shaft 3 is changed by the NC device 8 to suppress chatter vibration. May be performed.
Furthermore, in the above embodiment, when Fourier analysis of the vibration acceleration in the time domain detected by the detection means is performed, the control related to suppression of chatter vibration is performed using a waveform in which the vibration acceleration in the frequency domain shows the maximum value. However, the optimal rotational speed is calculated using a plurality of (for example, three) waveforms with the highest vibration acceleration value in the frequency domain, and the chatter vibration suppression effect is further improved. You may plan.

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基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-described embodiment, the configuration is such that the vibration acceleration of the rotating shaft is detected by the detection means, and the optimum rotation speed is calculated based on the detected vibration acceleration. 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. びびり振動の抑制制御に係るフローチャートである。It is a flowchart which concerns on suppression control of chatter vibration. 従来のびびり振動の抑制効果を示すグラフである。It is a graph which shows the conventional suppression effect of chatter vibration. 本発明のびびり振動の抑制効果を示すグラフである。It is a graph which shows the inhibitory effect of the chatter vibration of this invention.

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 (5)

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で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基づいて、びびり振動数及びそのびびり振動数における周波数領域の振動を算出すると共に、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、所定のパラメータに基づき、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演算手段と、その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、
前記演算手段は、前記最適回転速度を算出する際に、所定の条件に基づいて前記所定のパラメータを変更して回転速度の変化量が最小となるように最適回転速度を算出することを特徴とする工作機械の振動抑制装置。 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,
Based on the detection means for detecting the vibration in the time domain of the rotating shaft during rotation and the vibration in the time domain detected by the detection means, the vibration frequency and the vibration in the frequency domain at the chatter frequency are calculated. When the calculated vibration in the frequency domain exceeds a predetermined threshold, based on a predetermined parameter, calculating means for calculating the optimum rotational speed of the rotating shaft capable of suppressing chatter vibration, and the calculating means Rotation speed control means for rotating the rotation shaft at an optimum rotation speed, and
The calculating means calculates the optimum rotation speed so as to minimize the amount of change in rotation speed by changing the predetermined parameter based on a predetermined condition when calculating the optimum rotation speed. Vibration suppression device for machine tools. 演算手段は、所定のパラメータとなる下記の演算式（１）〜（４）に基づいて最適回転速度の演算を行うものであり、演算式（３）に基づいて算出した位相情報を所定の設定定数と比較し、その比較結果に基づいて演算式（４）のｋ値を変更するものである請求項１に記載の工作機械の振動抑制装置。
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）
最適回転速度＝６０×びびり振動数／（工具刃数×ｋ値）・・・（４） The calculation means calculates the optimum rotation speed based on the following calculation formulas (1) to (4) serving as predetermined parameters, and sets the phase information calculated based on the calculation formula (3) to a predetermined setting. The vibration suppression device for a machine tool according to claim 1, wherein the vibration suppression device for machine tool according to claim 1, wherein the k value of the arithmetic expression (4) is changed based on a comparison result with a constant.
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)
Optimal rotation speed = 60 x chatter frequency / (number of tool blades x k value) (4) 演算手段は、位相情報が所定の設定定数である０．５以上の場合には、演算式（４）のｋ値に１を加算して最適回転速度を演算するものである請求項２に記載の工作機械の振動抑制装置。   3. The calculating means according to claim 2, wherein when the phase information is 0.5 or more, which is a predetermined setting constant, the optimal rotation speed is calculated by adding 1 to the k value of the calculation formula (4). Vibration suppressor for machine tools. 演算手段は、位相情報が所定の設定定数である０．７５以上の場合には、演算式（４）のｋ値に１を加算して最適回転速度を演算するものである請求項２に記載の工作機械の振動抑制装置。   3. The calculating means according to claim 2, wherein when the phase information is not less than 0.75 which is a predetermined setting constant, the calculating means calculates the optimum rotation speed by adding 1 to the k value of the calculation formula (4). Vibration suppressor for machine tools. 演算手段は、演算式（４）のｋ値に対して、ｋの場合とｋ＋１の場合との２つの最適回転速度を夫々算出し、その２つの最適回転速度と現在の回転速度との差が小さい方の回転速度を選択することで、回転速度の変化量が最小となる最適回転速度を算出するものである請求項２に記載の工作機械の振動抑制装置。   The calculation means calculates two optimum rotation speeds for k and k + 1 for the k value in the equation (4), and the difference between the two optimum rotation speeds and the current rotation speed is calculated. 3. The vibration suppression device for a machine tool according to claim 2, wherein an optimum rotational speed at which a change amount of the rotational speed is minimized is calculated by selecting a smaller rotational speed.
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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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