JP6505145B2 - Stability limit diagram drawing device and stability limit diagram drawing method - Google Patents

Stability limit diagram drawing device and stability limit diagram drawing method Download PDF

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JP6505145B2
JP6505145B2 JP2017022723A JP2017022723A JP6505145B2 JP 6505145 B2 JP6505145 B2 JP 6505145B2 JP 2017022723 A JP2017022723 A JP 2017022723A JP 2017022723 A JP2017022723 A JP 2017022723A JP 6505145 B2 JP6505145 B2 JP 6505145B2
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chatter
rotational speed
stability limit
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JP2018126837A (en
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謙吾 河合
謙吾 河合
勝彦 大野
勝彦 大野
静雄 西川
静雄 西川
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DMG Mori Co Ltd
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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
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B23Q15/007—Automatic control or regulation of feed movement, cutting velocity or position of tool or work while the tool acts upon the workpiece
    • B23Q15/12—Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/404—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/406—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by monitoring or safety
    • G05B19/4063—Monitoring general control system

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Description

本発明は、工作機械を用い、切削工具によってワークを加工する際に生じる再生びびりについて、その安定限界線図を作成する安定限界線図作成装置、及び安定限界線図作成方法に関する。   The present invention relates to a stability limit diagram drawing apparatus and a stability limit diagram drawing method for producing a stability limit diagram of a reproduction chatter that occurs when a workpiece is machined by a cutting tool using a machine tool.

工作機械を用いた加工の分野では、ワークを効率よく加工すること及び加工コストを低減させることが永続的な課題として探求されている。一方、機械加工に求められる加工精度については、日増しに高い精度が求められるようになってきており、ワークを加工する際には、加工効率、加工コスト及び加工精度の各要素について要求される基準を満足するような加工条件を設定する必要がある。   In the field of machining using a machine tool, efficient machining of a work and reduction of machining cost are being sought as a permanent problem. On the other hand, with regard to the processing accuracy required for machining, high accuracy has come to be required day by day, and when processing a workpiece, it is required for each element of processing efficiency, processing cost and processing accuracy It is necessary to set processing conditions that satisfy the standard.

そして、従来、加工精度に係る要素のうち再生びびりに着目し、工具又はワークを回転させる主軸の回転速度と再生びびりを生じる工具の限界切り込み深さとの相関を示す線図であって、再生びびりを生じない安定領域と再生びびりを生じる不安定領域との境界を示す安定限界線図を作成して表示する装置が知られている（例えば、特許文献１参照）。   In the prior art, it is a diagram showing the correlation between the rotational speed of the spindle for rotating the tool or the work and the critical cutting depth of the tool causing the regeneration chatter, focusing on the regeneration chatter among the elements relating to machining accuracy. There is known an apparatus for creating and displaying a stability limit diagram showing the boundary between a stable area which does not generate a and an unstable area which generates reproduction chatter (see, for example, Patent Document 1).

この安定限界線図は、主軸回転速度が工具の固有振動数を当該工具の刃数で除した値であるときに、当該工具の限界切込み深さがピークを示す、即ち、安定領域がピークを示す所謂安定ポケット（１次安定ポケット）を有し、更に、この１次安定ポケットに対応する主軸回転速度を２以上の整数で除した各主軸回転速度において高次の安定ポケットを有する。   In this stability limit diagram, when the spindle rotational speed is a value obtained by dividing the natural frequency of a tool by the number of blades of the tool, the limit cutting depth of the tool shows a peak, that is, the stability region peaks. It has a so-called stable pocket (primary stable pocket), and further has a high-order stable pocket at each spindle rotational speed obtained by dividing the spindle rotational speed corresponding to this primary stable pocket by an integer of 2 or more.

斯くして、この安定限界線図によれば、オペレータは再生びびりを生じない主軸回転速度と工具の切り込み深さとの関係を瞬時に視覚的に認識することができ、当該再生びびりを生じない、効率の良い加工条件を設定することができる。このように、上記装置によれば、オペレータは装置に表示された安定限界線図を基準にすることにより、再生びびりを生じない範囲内で効率の良い加工条件を設定することができる。   Thus, according to this stability limit diagram, the operator can instantly visually recognize the relationship between the spindle rotational speed that does not generate regeneration chatter and the cutting depth of the tool, and does not generate the regeneration chatter, Efficient processing conditions can be set. As described above, according to the above-described apparatus, the operator can set efficient processing conditions within the range in which regeneration chattering does not occur by using the stability limit diagram displayed on the apparatus as a reference.

特許第５６２２６２６号公報Patent No. 5622626 gazette

ところで、工具系の固有振動数を求める方法には、ハンマリング試験やスイープ加振試験等があり、一般にこれらの方法は主軸が停止した状態で行われる。しかしながら、工具系の固有振動数は、主軸が停止している時と、主軸が回転して加工している時とでは異なることが分かっている。   By the way, methods of obtaining the natural frequency of the tool system include a hammering test, a sweep vibration test and the like, and these methods are generally performed in a state where the main shaft is stopped. However, it has been found that the natural frequency of the tool system differs between when the spindle is stationary and when the spindle is rotating and machining.

このため、上記従来の装置によって得られた安定限界線図を基にしては、再生びびりの生じない、効率の良い加工条件を、実際の加工に即した適正なものに設定することができなかった。   For this reason, based on the stability limit diagram obtained by the above-mentioned conventional apparatus, it is not possible to set an efficient processing condition which does not generate regeneration chatter to a proper one in line with the actual processing. The

本発明は、以上の実情に鑑みなされたものであって、実際の加工に即した適正な安定限界線図を作成することができる安定限界線図作成装置及び安定限界線図作成方法の提供を、その目的とする。   The present invention has been made in view of the above-described circumstances, and provides a stability limit diagram drawing apparatus and a stability limit diagram drawing method capable of creating an appropriate stability limit diagram in line with actual processing. , Its purpose.

上記課題を解決するための本発明は、少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成方法であって、
前記工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出し、
検出した前記振動系の振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、当該再生びびりの周波数を、測定再生びびり周波数として該再生びびりが生じたときの前記主軸回転速度と関連付けて記憶し、
前記工具、前記工具ホルダ、前記ワーク固定用治具及び前記工作機械の組み合わせに基づいて任意に設定した前記振動系の減衰比、並びに記憶した前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記振動系の固有振動数を算出し、算出した固有振動数、前記設定した減衰比、並びに記憶した前記測定再生びびり周波数及び前記主軸回転速度に基づいて、前記安定限界線図を作成するようにした安定限界線図作成方法に係る。 The present invention for solving the above-mentioned problems depends on at least the tool used, the tool holder for holding the tool, the jig for fixing the work, and the natural frequency and damping ratio of the vibration system whose value differs depending on the combination of the machine tool. A stability limit diagram drawing method for creating a stability limit diagram, which is a correlation diagram between a spindle rotation speed and a limit cutting depth of the tool, which shows the boundary between the stable region and the unstable region of regenerative chatter. ,
Detecting the magnitude and frequency of the vibration of the vibration system generated when processing a workpiece using the tool;
Based on the detected magnitude of vibration of the vibration system, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is measured Storing in association with the spindle rotational speed when the reproduction chatter occurs as a reproduction chatter frequency,
Based on the damping ratio of the vibration system arbitrarily set based on the combination of the tool, the tool holder, the jig for fixing the work and the machine tool, and based on the stored measured regenerative chatter frequency and the spindle rotational speed. The characteristic limit of the vibration system is calculated, and the stability limit diagram is created on the basis of the calculated characteristic frequency, the set attenuation ratio, and the stored measured regenerative chatter frequency and the spindle rotational speed. It relates to a method of creating a stability limit diagram.

そして、この安定限界線図作成方法は、
少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成装置であって、
前記再生びびりの周波数と前記主軸回転速度との関係を記憶するデータ記憶部と、
前記工具が装着される付近に配置され、該工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出する振動検出部と、
前記振動検出部によって検出された振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、該再生びびりの周波数を測定再生びびり周波数として、該再生びびりが生じたときの前記主軸回転速度と関連付けて前記データ記憶部に格納するびびり検出部と、
前記工具、前記工具ホルダ、前記ワーク固定用治具及び前記工作機械の組み合わせに基づいて任意に設定した前記振動系の減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記振動系の固有振動数を算出する算出部と、
前記算出部により算出された固有振動数、前記設定した減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて、前記安定限界線図を作成する線図作成部と、
当該線図作成部により作成された前記安定限界線図を表示する表示部とを備えた安定限界線図作成装置によって好適に実施される。 And this stability limit diagram creation method is
The stability region and instability of the regenerative chatter, the value of which varies according to the natural frequency and damping ratio of the vibration system that differs depending on the combination of at least the tool used, the tool holder holding the tool, the work fixing jig and the machine tool A stability limit diagram drawing device for producing a stability limit diagram, which is a correlation diagram of a spindle rotation speed and a limit cutting depth of the tool, showing a boundary with a region,
A data storage unit for storing the relationship between the frequency of the reproduction chatter and the spindle rotational speed;
A vibration detection unit disposed in the vicinity where the tool is mounted and detecting the magnitude and frequency of the vibration of the vibration system generated when a workpiece is machined using the tool;
Based on the magnitude of vibration detected by the vibration detection unit, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is determined. A chatter detection unit which is stored as the measurement playback chatter frequency in the data storage unit in association with the spindle rotational speed when the playback chatter occurs;
Damping ratio of the vibration system arbitrarily set based on the combination of the tool, the tool holder, the jig for fixing the work, and the machine tool, and the measurement reproduction chatter frequency and the spindle stored in the data storage unit A calculation unit that calculates the natural frequency of the vibration system based on the rotational speed;
A diagram for creating the stability limit diagram based on the natural frequency calculated by the calculation unit, the set attenuation ratio, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit. The creation department,
It is suitably implemented by the stability limit diagram drawing device provided with the display part which displays the said stability limit diagram drawn by the said line drawing creation part.

上記構成を備えた本発明によれば、まず、工具が装着される付近に配置された振動検出部によって、該工具を用いてワークを加工した際に生じる振動系の振動の大きさ及びその周波数が検出される。そして、この振動検出部によって検出される振動の大きさを基に、びびり検出部によって工具に再生びびりが生じたかどうかが判別され、工具に再生びびりが生じたと判断された場合には、当該再生びびりの周波数が測定再生びびり周波数として、当該再生びびりが生じたときの主軸回転速度と関連付けてデータ記憶部に格納される。   According to the present invention having the above-described configuration, first, the magnitude and frequency of the vibration of the vibration system generated when the workpiece is processed using the tool by the vibration detection unit disposed in the vicinity where the tool is mounted Is detected. Then, based on the magnitude of the vibration detected by the vibration detection unit, the chatter detection unit determines whether or not the reproduction chatter has occurred on the tool, and when it is determined that the reproduction chatter has occurred on the tool, the reproduction The frequency of chattering is stored in the data storage unit as a measurement replay chatter frequency in association with the spindle rotational speed at which the chattering regeneration occurs.

そして、データ記憶部に測定再生びびり周波数と対応する主軸回転速度が格納されると、算出部により、当該振動系の固有振動数が算出される。即ち、再生びびり周波数、これに対応する主軸回転速度、振動系の固有振動数及び減衰比との間には、所定の関係が存在する、言い換えれば、これらの関係を所定の関係式で表わせることが知られており、算出部は、当該関係式に基づいて、未知数である振動系の固有振動数及び減衰比の内、例えば、減衰比を経験値から推定される所定値に設定して、残りの未知数である振動系の固有振動数を算出する。   Then, when the spindle rotational speed corresponding to the measured reproduction chatter frequency is stored in the data storage unit, the calculation unit calculates the natural frequency of the vibration system. That is, there is a predetermined relationship between the regenerative chatter frequency, the corresponding spindle rotational speed, the natural frequency of the vibration system and the damping ratio, in other words, these relationships can be expressed by a predetermined relationship Among the natural frequencies and damping ratios of the vibration system which are unknowns, for example, the damping unit is set to a predetermined value estimated from the empirical value, based on the relational expression. Calculate the natural frequency of the vibration system, which is the remaining unknown.

次に、線図作成部により、前記算出部により算出された固有振動数、設定した減衰比、並びに前記データ記憶部に格納された測定再生びびり周波数及び主軸回転速度に基づいて、安定限界線図が作成され、当該線図作成部により作成された安定限界線図が表示部によって表示される。   Next, based on the natural frequency calculated by the calculation unit, the set attenuation ratio, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit by the drawing unit, the stability limit diagram Is created and the stability limit diagram created by the diagram creation unit is displayed by the display unit.

このように、本発明によれば、振動系全体に係る固有振動数を算出し、算出した振動系全体に係る固有振動数を用いて安定限界線図を作成するようにしているので、工具のみの固有振動数を基に安定限界線図を作成する従来に比べて、実際の加工に即したより現実的な安定限界線図を作成することができ、また、このような実加工に即した安定限界線図を用いることで、再生びびりの生じない効率の良い加工条件を、実加工に即した適正なものに設定することがでる。   As described above, according to the present invention, the natural frequency related to the whole vibration system is calculated, and the stability limit diagram is created using the calculated natural frequency related to the whole vibration system. Compared to the conventional method of creating a stability limit diagram based on the natural frequency of the above, it is possible to create a more realistic stability limit diagram according to actual processing, and according to such actual processing By using the stability limit diagram, it is possible to set efficient processing conditions that do not cause regeneration chatter to be appropriate for actual processing.

本発明において、前記算出部は、前記データ記憶部に格納されたデータを確認して、複数組の前記測定再生びびり周波数と前記主軸回転速度との関係データが格納されている場合には、該複数組の前記測定再生びびり周波数と前記主軸回転速度との関係データに基づいて、前記振動系の減衰比及び固有振動数を算出するように構成され、
更に、前記線図作成部は、前記算出部により算出された固有振動数、減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記安定限界線図を作成するように構成されていても良い。 In the present invention, the calculation unit confirms the data stored in the data storage unit, and when a plurality of sets of relationship data between the measurement reproduction chatter frequency and the spindle rotational speed are stored, The damping ratio and the natural frequency of the vibration system are calculated based on the relationship data between a plurality of sets of the measured regenerative chatter frequency and the spindle rotational speed,
Furthermore, the diagram creation unit is the stability limit diagram based on the natural frequency and the damping ratio calculated by the calculation unit, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit. It may be configured to create

上述したように、再生びびり周波数、これに対応する主軸回転速度、振動系の固有振動数及び減衰比の関係は所定の関係式で表わすことができる。したがって、測定再生びびり周波数及びその時の主軸回転速度に係るデータが少なくとも２組あれば、振動系の固有振動数及び減衰比を未知数とする２つの関係式を得ることができ、これらの関係式を連立方程式として解くことで、未知数である前記固有振動数及び減衰比を算出することができる。   As described above, the relationship between the regenerative chatter frequency, the corresponding spindle rotational speed, the natural frequency of the vibration system, and the damping ratio can be expressed by a predetermined relational expression. Therefore, if there are at least two sets of data relating to the measured regenerative chatter frequency and the main spindle rotational speed at that time, two relational expressions can be obtained with the natural frequency and damping ratio of the vibration system as unknowns. By solving as simultaneous equations, it is possible to calculate the natural frequency and the damping ratio which are unknowns.

斯くして、前記算出部は、上記のようにして、データ記憶部に格納された複数組の測定再生びびり周波数と主軸回転速度との関係データに基づいて、振動系の減衰比及び固有振動数を算出する。そして、線図作成部は、この算出部により算出された固有振動数、減衰比、並びに前記データ記憶部に格納された測定再生びびり周波数及び主軸回転速度に基づいて安定限界線図を作成し、作成された安定限界線図が前記表示部に表示される。   Thus, the calculation unit is configured as described above, based on the relationship data between the plurality of sets of measured and reproduced chatter frequencies and the spindle rotational speed stored in the data storage unit, the damping ratio and the natural frequency of the vibration system. Calculate Then, the diagram creating unit creates a stability limit diagram based on the natural frequency and the damping ratio calculated by the calculating unit, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit, The created stability limit diagram is displayed on the display unit.

また、本発明において、前記算出部は、前記振動系の固有振動数及び減衰比をそれぞれ任意の複数の値に設定し、各設定値について、所定式で表わされる前記再生びびり周波数、主軸回転速度、固有振動数及び減衰比との関係を基に、前記データ記憶部に記憶された複数の主軸回転速度に対応した理論再生びびり周波数をそれぞれ算出し、各設定値ごとに、前記各主軸回転速度に対応する前記理論再生びびり周波数と前記測定再生びびり周波数との差をそれぞれ算出して積算し、積算された差が最小値を示す前記設定値を、前記振動系の減衰比及び固有振動数として同定するように構成されていても良い。   Further, in the present invention, the calculation unit sets the natural frequency and the damping ratio of the vibration system to a plurality of arbitrary values, and the reproduction chatter frequency and the spindle rotational speed represented by a predetermined formula for each set value. The theoretical reproduction chatter frequency corresponding to the plurality of spindle rotational speeds stored in the data storage unit is calculated based on the relationship between the natural frequency and the damping ratio, and the respective spindle rotational speeds are calculated for each setting value. The difference between the theoretical reproduction chatter frequency and the measurement reproduction chatter frequency corresponding to each is calculated and integrated, and the setting value indicating the minimum value of the accumulated difference is the damping ratio and the natural frequency of the vibration system. It may be configured to identify.

或いは、前記算出部は、前記振動系の固有振動数及び減衰比をそれぞれ任意の複数の値に設定し、各設定値について、所定式で表わされる前記再生びびり周波数、主軸回転速度、固有振動数及び減衰比との関係を基に、前記データ記憶部に記憶された複数の測定再生びびり周波数に対応した理論主軸回転速度をそれぞれ算出し、各設定値ごとに、前記各測定再生びびり周波数に対応する前記理論主軸回転速度と前記データ記憶部に格納された主軸回転速度との差をそれぞれ算出して積算し、積算された差が最小値を示す前記設定値を、前記振動系の減衰比及び固有振動数として同定するように構成されていても良い。   Alternatively, the calculation unit sets each of the natural frequency and the damping ratio of the vibration system to a plurality of arbitrary values, and the reproduction chatter frequency, the spindle rotational speed, and the natural frequency represented by a predetermined formula for each set value. The theoretical spindle rotational speeds corresponding to the plurality of measurement reproduction chatter frequencies stored in the data storage unit are respectively calculated based on the relationship between the measurement and the damping ratio, and the measurement reproduction chatter frequencies are supported for each set value. The difference between the theoretical main spindle rotational speed and the main spindle rotational speed stored in the data storage unit is calculated and integrated, and the setting value indicating the minimum value of the integrated difference is the damping ratio of the vibration system and It may be configured to be identified as a natural frequency.

このような構成の算出部によれば、上述した連立方程式を解く手法によることなく、振動系の減衰比及び固有振動数を同定することができる。   According to the calculation unit having such a configuration, it is possible to identify the damping ratio and the natural frequency of the vibration system without using the method of solving the simultaneous equations described above.

また、前記線図作成部は、作成した前記安定限界線図の各安定ポケットの頂点に対応した主軸回転速度をＳ(min−１)、算出された前記固有振動数をωｎ(Hz)、前記工具の刃数をＮとして下式によって整数ｋを算出するとともに、算出した整数ｋの値を対応する安定ポケット付近に配置した安定限界線図を作成するように構成されていても良い。

Figure 0006505145
但し、［］はガウス記号である。 Further, the diagram creating unit may set the spindle rotational speed corresponding to the top of each stable pocket in the created stability limit diagram to S (min −1 ), and the calculated natural frequency to be ω n (Hz), The integer k may be calculated by the following equation, where the number of blades of the tool is N, and a stability limit diagram may be created in which the calculated value of the integer k is disposed near the corresponding stability pocket.
Figure 0006505145
 However, [] is a Gaussian symbol.

前記安定限界線図では、工具の限界切り込み深さがピーク（極大値）を示す主軸転速度が複数存在し、各ピークを示す山形部は安定ポケットと称される。そして、最も高い主軸回転速度は、振動系の固有振動数を工具の刃数で除した回転速度で１次安定ポケットと称され、この主軸回転速度を順次大きい整数（２，３・・・）で除した主軸回転速度に対応する安定ポケットは、２次安定ポケット、３次安定ポケット・・・と称される。そして、安定限界線図は、安定ポケットが高次になるほどその幅が狭まるという特徴を有する。   In the stability limit diagram, there are a plurality of spindle rotation speeds at which the limit cutting depth of the tool shows a peak (maximum value), and the chevron portion showing each peak is called a stable pocket. The highest spindle rotational speed is referred to as a primary stable pocket by the rotational speed obtained by dividing the natural frequency of the vibration system by the number of blades of the tool, and this spindle rotational speed is sequentially increased by an integer (2, 3...) The stable pockets corresponding to the spindle rotational speed divided by are referred to as secondary stable pockets, tertiary stable pockets. And, the stability limit diagram is characterized in that the width becomes narrower as the stability pocket becomes higher.

上記数式１によって算出される整数ｋは安定ポケットの次数に当たるものであり、この次数ｋを対応する安定ポケットの付近に表示することで、オペレータは、安定限界線図で示される各安定ポケットの次数を容易に理解することができる。   The integer k calculated by the above equation 1 corresponds to the order of the stable pocket, and by displaying this order k near the corresponding stable pocket, the operator can determine the order of each stable pocket shown in the stability limit diagram. Can be easily understood.

以上説明したように、本発明によれば、振動系全体に係る固有振動数を算出し、算出した振動系全体に係る固有振動数を用いて安定限界線図を作成するようにしているので、工具のみの固有振動数を基に安定限界線図を作成する従来に比べて、実際の加工に即したより現実的な安定限界線図を作成することができ、また、このような実加工に即した安定限界線図を用いることで、再生びびりの生じない効率の良い加工条件を、実加工に即した適正なものに設定することがでる。   As described above, according to the present invention, the natural frequency related to the whole vibration system is calculated, and the stability limit diagram is created using the calculated natural frequency related to the whole vibration system. Compared to the conventional method of creating a stability limit diagram based on the natural frequency of only a tool, it is possible to create a more realistic stability limit diagram in line with actual processing, and also in such actual processing By using the stable limit diagram in line, it is possible to set efficient processing conditions that do not cause regeneration chatter to be appropriate for actual processing.

本発明の一実施形態に係る安定限界線図作成装置が適用される工作機械の概略構成を示した斜視図である。BRIEF DESCRIPTION OF THE DRAWINGS It is the perspective view which showed schematic structure of the machine tool with which the stability-limit-diagram production apparatus based on one Embodiment of this invention is applied. 本実施形態に係る安定限界線図作成装置の概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the stability-limit-diagram production apparatus which concerns on this embodiment. ２自由度系の切削モデルを示した説明図である。It is explanatory drawing which showed the cutting model of 2 degrees of freedom system. 本実施形態で作成され、表示される安定限界線図の一例を示した説明図である。It is explanatory drawing which showed an example of the stability limit diagram produced and displayed by this embodiment.

以下、本発明の一実施形態に係る安定限界線図作成装置について、図面を参照しながら説明する。   Hereinafter, a stability limit diagram drawing creating apparatus according to an embodiment of the present invention will be described with reference to the drawings.

Ａ．工作機械
まず、本例の安定限界線図作成装置が適用される工作機械の概略について説明する。図１に示すように、本例の工作機械２０は、ベッド２１と、このベッド２１上に立設されたコラム２２と、このコラム２２の前面（加工領域側の面）に矢示Ｚ軸方向に移動自在に設けられた主軸頭２３と、軸中心に回転自在に主軸頭２３に保持された主軸２４と、主軸頭２３より下方のベッド２１上に矢示Ｙ軸方向に移動自在に設けられたサドル２５と、サドル２５上に矢示Ｘ軸方向に移動自在に配設されたテーブル２６と、このテーブル２６をＸ軸方向に移動させるＸ軸送り機構２９と、サドル２５をＹ軸方向に移動させるＹ軸送り機構２８と、主軸頭２３をＺ軸方向に移動させるＺ軸送り機構２７と、主軸２４を回転させる主軸モータ（図示せず）とを備えている。 A. Machine Tool First, an outline of a machine tool to which the stability limit diagram creation device of this example is applied will be described. As shown in FIG. 1, the machine tool 20 of this example has a bed 21, a column 22 erected on the bed 21, and a front surface (surface on the processing area side) of the column 22 in the Z-axis direction Provided on the bed 21 below the main spindle head 23 so as to be movable in the direction indicated by the arrow Y. Saddle 25, a table 26 disposed movably in the direction of the arrow X on the saddle 25, an X-axis feed mechanism 29 for moving the table 26 in the X-axis direction, and a saddle 25 in the Y-axis direction A Y-axis feed mechanism 28 for moving, a Z-axis feed mechanism 27 for moving the spindle head 23 in the Z-axis direction, and a spindle motor (not shown) for rotating the spindle 24 are provided.

前記Ｘ軸送り機構２９、Ｙ軸送り機構２８、Ｚ軸送り機構２７及び主軸モータ（図示せず）等は、図示しない制御装置によりその作動が制御される。具体的には、前記制御装置（図示せず）に格納されたＮＣプログラムが適宜実行され、このＮＣプログラムに従った制御の下で前記Ｘ軸送り機構２９、Ｙ軸送り機構２８、Ｚ軸送り機構２７及び主軸モータ（図示せず）が駆動されて、主軸２４がその軸中心に回転するとともに、当該主軸２４とテーブル２６とが３次元空間内で相対的に移動することで、テーブル２６上に、ワーク固定用治具ＷＪによって固定されたワークＷが、主軸２４に装着された工具ＴＬによって加工される。尚、工具ＴＬは工具ホルダＴＨにより保持された状態で主軸２４に装着されており、図１には、工具ＴＬの一例としてエンドミルを図示している。 The operation of the X-axis feed mechanism 29, the Y-axis feed mechanism 28, the Z-axis feed mechanism 27, the spindle motor (not shown), etc. is controlled by a control device (not shown). Specifically, an NC program stored in the control device (not shown) is appropriately executed, and under control according to this NC program, the X-axis feed mechanism 29, the Y-axis feed mechanism 28, the Z-axis feed The mechanism 27 and the spindle motor (not shown) are driven to rotate the spindle 24 about its axis, and the spindle 24 and the table 26 move relative to each other in the three-dimensional space, thereby causing the table 26 to move. to, a fixed workpiece W by the workpiece fixing jig WJ is processed by the mounted tool TL to the spindle 24. The tool TL is mounted on the spindle 24 in a state of being held by the tool holder TH, and FIG. 1 shows an end mill as an example of the tool TL.

Ｂ．安定限界線図作成装置
次に、本例の安定限界線図作成装置について説明する。図２に示すように、本例の安定限界線図作成装置１は、前記工作機械２０の主軸頭２３に取り付けられた加速度センサ２の他、びびり検出部３、データ記憶部４、算出部５、線図作成部６及び表示装置７から構成される。 B. Stability Limit Diagram Drawing Device Next, the stability limit diagram drawing device of this example will be described. As shown in FIG. 2, in addition to the acceleration sensor 2 attached to the spindle head 23 of the machine tool 20, the stability limit diagram drawing device 1 of this example includes a chatter detection unit 3, a data storage unit 4 and a calculation unit 5. , And a diagram creating unit 6 and a display device 7.

尚、この安定限界線図作成装置１は、加速度センサ２を除いて、ＣＰＵ，ＲＯＭ，ＲＡＭの他、キーボード等の入力ディバイスやディスプレイなどを備えた一般的なコンピュータから構成することができ、また、工作機械２０に設けられる制御装置に組み込むことができる。制御装置に組み込む場合、前記表示装置７は操作盤のタッチパネルで構成することができる。また、前記びびり検出部３、算出部５及び線図作成部６は、それぞれ適宜ソフトウエアによってその機能が実現され、前記データ記憶部４はＲＡＭなどの適宜記憶媒体によって構成される。   The stability limit diagram drawing device 1 can be constituted by a general computer provided with an input device such as a keyboard, a display, etc. in addition to the CPU, ROM, RAM, except for the acceleration sensor 2. , And the control device provided in the machine tool 20. When incorporated in a control device, the display device 7 can be configured by a touch panel of an operation panel. Further, the functions of the chatter detection unit 3, the calculation unit 5 and the diagram creation unit 6 are appropriately realized by software, and the data storage unit 4 is configured by an appropriate storage medium such as a RAM.

前記加速度センサ２は、前記工具ＴＬによってワークＷを加工しているときに、工具ＴＬ、該工具ＴＬを保持する工具ホルダＴＨ、ワーク固定用治具ＷＪ及び工作機械２０によって構成される振動系の振動を検出して、当該振動に応じた信号を前記びびり検出部１１に出力する。この加速度センサ２による振動の検出は、加工が行なわれている間、常に実行される。   The acceleration sensor 2 is a vibration system constituted of a tool TL, a tool holder TH for holding the tool TL, a workpiece fixing jig WJ, and the machine tool 20 when the workpiece W is processed by the tool TL. The vibration is detected, and a signal corresponding to the vibration is output to the chatter detection unit 11. The detection of the vibration by the acceleration sensor 2 is always performed while the processing is being performed.

前記びびり検出部３は、前記加速度センサ２から出力される振動に係る信号を受信し、受信した信号をフーリエ解析（周波数解析）により解析して、工具ＴＬに生じている振動の周波数とその大きさを算出する。そして、得られた振動の大きさが所定の閾値を超えたとき、そのときの振動周波数を測定再生びびり周波数として、前記工作機械２０から取得される主軸２４の回転速度（主軸回転速度）と関連付けて、前記データ記憶部４に格納する処理を行う。   The chatter detection unit 3 receives the signal relating to the vibration output from the acceleration sensor 2 and analyzes the received signal by Fourier analysis (frequency analysis) to determine the frequency and magnitude of the vibration occurring in the tool TL. Calculate the Then, when the magnitude of the obtained vibration exceeds a predetermined threshold, the vibration frequency at that time is measured and correlated with the rotational speed (spindle rotational speed) of the main spindle 24 acquired from the machine tool 20 as the chattering frequency. Then, the process of storing in the data storage unit 4 is performed.

尚、主軸回転速度は工作機械２０の主軸モータ（図示せず）に設けられたロータリエンコーダ（図示せず）から取得することができ、或いは、工作機械２０の制御信号から取得することができる。また、前記データ記憶部４には、びびり検出部３によって再生びびりが検出されるたびに、そのときの測定再生びびり周波数と主軸回転速度とが関連付けられて格納される。   The spindle rotational speed can be acquired from a rotary encoder (not shown) provided on a spindle motor (not shown) of the machine tool 20, or can be acquired from a control signal of the machine tool 20. Further, each time the reproduction detection is detected by the chat detection unit 3, the data storage unit 4 stores the measurement reproduction chatter frequency and the spindle rotational speed in association with each other.

前記算出部５は、前記データ記憶部４に格納された測定再生びびり周波数及び主軸回転速度に係るデータを基に、前記振動系の固有振動数及び減衰比を同定する。   The calculation unit 5 identifies the natural frequency and the damping ratio of the vibration system on the basis of the data concerning the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit 4.

この固有振動数及び減衰比の同定に係る説明の前に、まず、再生びびりに係る基本的な理論について説明する。   Before describing the identification of the natural frequency and the damping ratio, first, the basic theory of the regeneration chatter will be described.

図３に示した物理モデルは、上述した工作機械２０のように、工具ＴＬとワークＷとをＸ軸とＹ軸の２つの送り軸方向に相対移動させて加工する２自由度系の物理モデルである。この物理モデルに基づいて、再生びびり振動が発生する条件をY・Altintasが考案した解析方法により求める。   The physical model shown in FIG. 3 is a physical model of a two-degree-of-freedom system in which the tool TL and the workpiece W are moved relative to each other in the X axis and Y axis feed directions as in the machine tool 20 described above. It is. Based on this physical model, the conditions under which regenerative chatter vibration occurs are determined by an analysis method devised by Y. Altintas.

この物理モデルにおいて、前記振動系の運動方程式は下記の２式で表わされる。
ｘ"＋2ζxωxｘ'＋ωx 2ｘ＝Ｆx／ｍx
ｙ"＋2ζyωyｙ'＋ωy 2ｙ＝Ｆy／ｍy
但し、ωxは前記振動系のＸ軸方向の固有振動数[rad/sec]、ωyは前記振動系のＹ軸方向の固有振動数[rad/sec]であり、ζxは前記振動系のＸ軸方向の減衰比[%]、ζyは前記振動系のＹ軸方向の減衰比[%]である。また、ｍxは前記振動系のＸ軸方向の等価質量[kg]、ｍyは前記振動系のＹ軸方向の等価質量[kg］であり、Ｆxは工具ＴＬに作用するＸ軸方向の切削動力[N]であり、Ｆyは工具ＴＬに作用するＹ軸方向の切削動力[N]である。また、ｘ"及びｙ"はそれぞれ時間の２階微分を示し、ｘ'及びｙ'はそれぞれ時間の１階微分を示す。 In this physical model, the equation of motion of the vibration system is expressed by the following two equations.
x "+ 2ζ x ω x x + ω x 2 x = F x / m x
y "+ 2ζ y ω y y '+ ω y 2 y = F y / m y
Where ω x is the natural frequency [rad / sec] in the X-axis direction of the vibration system, ω y is the natural frequency [rad / sec] in the Y-axis direction of the vibration system, and ζ x is the vibration system X-axis direction of the damping ratio of [%], the zeta y is the vibration system Y-axis direction of the damping ratio of [%]. Further, m x is the equivalent mass [kg] in the X-axis direction of the vibration system, and m y is the equivalent mass [kg] in the Y-axis direction of the vibration system, and F x is the X-axis direction acting on the tool TL The cutting power [N], F y is the cutting power [N] in the Y-axis direction acting on the tool TL. Also, x "and y" indicate the second derivative of time, and x 'and y' indicate the first derivative of time.

上記切削動力Ｆxと切削動力Ｆyとは、以下の数式２で表され、当該数式２におけるａｘｘと、ａｘｙと、ａｙｘと、ａｙｙとは以下の数式３乃至６で表される。なお、ａｐは切込深さであり、Ｋｔは主分力の比切削抵抗、Ｋｒは主分力と背分力との比率、φｓｔは切込開始角、φｅｘは切込終了角である。
The cutting power F x and the cutting power F y are represented by Formula 2 below, and a xx , a xy , a yx , and a yy in the formula 2 are represented by Formulas 3 to 6 below. Ru. Where a p is the depth of cut, K t is the specific cutting force of the main force, K r is the ratio of the main force to the back force, φ st is the cut start angle, and φ ex is the cut It is an end angle.

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

また、上記運動方程式の固有値Λは以下の数式７で表される。尚、数式７におけるａ０とａ１とは以下の数式８，９で表される。 Further, the eigenvalue Λ of the above equation of motion is expressed by the following equation 7. Incidentally, a 0 and a 1 in Expression 7 are expressed by the following Expressions 8 and 9, respectively.

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

ここで、Ｇｘｘ（ｉω）はＸ軸方向の伝達関数、Ｇｙｙ（ｉω）はＹ軸方向の伝達関数である。また、固有値Λは実部及び虚部を有し、Λ＝ΛＲ＋ｉΛＩで表される。この固有値Λは以下の数式１０で表される関係を充足する必要がある。 Here, G xx (iω) is a transfer function in the X-axis direction, and G yy (iω) is a transfer function in the Y-axis direction. Further, the eigenvalue Λ has a real part and an imaginary part, and is expressed as Λ = Λ R + iΛ I. This eigenvalue Λ needs to satisfy the relationship expressed by Equation 10 below.

Figure 0006505145
Figure 0006505145

ここに、ωｃは再生びびり周波数であり、Ｔは下記数式１１で表される切刃通過周波数である。尚、数式１１におけるＮは刃数であり、Ｓは主軸回転速度である。 Here, ω c is a regenerative chatter frequency, and T is a cutting edge passing frequency represented by the following Equation 11. In Equation 11, N is the number of blades, and S is the spindle rotational speed.

Figure 0006505145
Figure 0006505145

ここで、簡略化のために、伝達関数Ｇｘｘ（ｉω）及び伝達関数Ｇｙｙ（ｉω）が同一であると考えると、伝達関数Ｇｘｘ（ｉω），Ｇｙｙ（ｉω）は以下の数式１２で表される。 Here, assuming that the transfer function G xx (iω) and the transfer function G yy (iω) are identical for simplification, the transfer functions G xx (iω) and G yy (iω) have the following formula 12 Is represented by

Figure 0006505145
Figure 0006505145

そして、上記数式１２を前記数式７，８，９に代入することで、以下の数式１３，１４，１５が得られる。   Then, by substituting the equation 12 into the equations 7, 8 and 9, the following equations 13, 14 and 15 can be obtained.

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

Figure 0006505145
Figure 0006505145

ここで、Ａ及びＢは共に実数であるため、上記数式１５におけるルート中の値の正負によって、以下の２通りの算出式が成立する。   Here, since both A and B are real numbers, the following two calculation formulas are established depending on whether the value in the route in the above equation 15 is positive or negative.

即ち、Ｂ２−４Ａ＞０のときは、以下の数式１６が成立する。 That is, when B 2 −4A> 0, the following equation 16 is established.

Figure 0006505145
Figure 0006505145

そして、前記数式１０及び数式１６から、再生びびり周波数ωｃ、切刃通過周波数Ｔ、固有振動数ωｎ、及び減衰比ζの関係を示す以下の数式１７が成立する。 Then, the following equation 17 showing the relationship among the regenerative chatter frequency ω c , the cutting edge passing frequency T, the natural frequency ω n , and the damping ratio 成立 is established from the equation 10 and the equation 16.

Figure 0006505145
Figure 0006505145

そして、この数式１７を整理して以下の数式１８が得られる。   Then, the following equation 18 is obtained by arranging this equation 17:

Figure 0006505145
Figure 0006505145

一方、Ｂ２−４Ａ＜０のときは、以下の数式１９が成立する。 On the other hand, when the B 2 -4A <0, the following equation 19 is established.

Figure 0006505145
Figure 0006505145

そして、前記数式１０及び数式１９から、再生びびり周波数ωｃ、切刃通過周波数Ｔ、固有振動数ωｎ、及び減衰比ζの関係を示す以下の数式２０が成立する。 Then, from the above Equations 10 and 19, the following Equation 20 showing the relationship between the regenerative chatter frequency ω c , the cutting edge passing frequency T, the natural frequency ω n , and the damping ratio 成立 holds.

Figure 0006505145
Figure 0006505145

そして、この数式２０を整理して以下の数式２１が得られる。   Then, the following equation 21 is obtained by arranging the equation 20.

Figure 0006505145
Figure 0006505145

以上から、算出部５は、上記数式１８又は数式２１にしたがって、データ記憶部４に格納された測定再生びびり周波数ωｃ及びそのときの主軸回転速度Ｓを基に、前記振動系の固有振動数ωｎ及び減衰比ζを同定する。以下、前記振動系の固有振動数ωｎ及び減衰比ζを同定する４つ態様、即ち、第１の態様、第２の態様、第３の態様及び第４の態様について説明する。 From the above, the calculation unit 5 calculates the natural frequency of the vibration system based on the measurement reproduction chatter frequency ω c and the spindle rotational speed S at that time stored in the data storage unit 4 according to the equation 18 or 21 above. Identify ω n and damping ratio ζ. Hereinafter, four modes for identifying the natural frequency ω n and the damping ratio ζ of the vibration system, that is, the first mode, the second mode, the third mode and the fourth mode will be described.

［第１の態様］
算出部５は、前記データ記憶部４に少なくとも１組の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、その測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データ、並びに工具ＴＬの刃数Ｎに基づき、上記数式１８又は数式２１にしたがって、前記振動系の減衰比ζ及び固有振動数ωｎを同定する。 [First aspect]
Calculating unit 5, at least one set of measurements regenerative chatter when the relationship data of the frequency omega c and the main shaft rotational speed S are stored, the relationship between the measured regenerative chatter frequency omega c and the main shaft rotational speed S in the data storage unit 4 Based on the data and the number of blades N of the tool TL, the damping ratio ζ and the natural frequency ω n of the vibration system are identified according to Equation 18 or Equation 21 above.

尚、算出に用いられる数式は、数式１８又は数式２１で一つの式であるが、未知数は減衰比ζと固有振動数ωｎの２つであるため、このままでは未知数を算出することができない。そこで、例えば、減衰比ζを経験値から推定して、残りの未知数である固有振動数ωｎを算出する。減衰比ζの推定は、例えば振動系をハンマ等を用いて振動させ、その減衰の状態を実際に測定することで、例えば、下式によって算出することができる。
ζ＝Ｄ／（２×２７．３ｆ０）
但し、Ｄは１秒当たりの減衰量（ｄＢ／ｓｅｃ）、ｆ０はピークの振動周波数である。 Incidentally, although the mathematical formulas used for the calculation are one formula in Formula 18 or Formula 21, since the unknowns are two, the damping ratio ζ and the natural frequency ω n , the unknowns can not be calculated as it is. Therefore, for example, the damping ratio ζ is estimated from the experience value, and the natural frequency ω n which is the remaining unknown is calculated. The damping ratio 推定 can be calculated, for example, by the following equation by, for example, vibrating the vibration system using a hammer or the like and actually measuring the state of the damping.
ζ = D / (2 × 27.3f 0 )
Where D is the attenuation per second (dB / sec) and f 0 is the peak oscillation frequency.

尚、前記データ記憶部４に複数組の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、算出部５は、以下の第２の態様〜第４の態様のいずれかの態様によって、減衰比ζ及び固有振動数ωｎを同定するのが好ましい。 In the case where the data storage unit 4 stores the relationship data of a plurality of sets of measurement / reproduction chatter frequency ω c and the spindle rotational speed S, the calculation unit 5 is any of the second to fourth aspects described below. It is preferable to identify the damping ratio ζ and the natural frequency ω n according to any aspect.

［第２の態様］
算出部５は、前記データ記憶部４に少なくとも２組の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、その測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データ、並びに工具ＴＬの刃数Ｎに基づき、上記数式１８又は数式２１にしたがって、前記振動系の減衰比ζ及び固有振動数ωｎを同定する。 [Second aspect]
When the data storage unit 4 stores the relationship data of at least two sets of measured regenerative chatter frequency ω c and spindle rotational speed S in the data storage unit 4, the relationship between the measured regenerative chatter frequency ω c and spindle rotational speed S Based on the data and the number of blades N of the tool TL, the damping ratio ζ and the natural frequency ω n of the vibration system are identified according to Equation 18 or Equation 21 above.

データ記憶部４に２組の測定再生びびり周波数及び主軸回転速度の関係データが格納されている場合、数式１８又は数式２１にしたがって、前記振動系の減衰比ζ及び固有振動数ωｎを未知数とする２の方程式が得られる。したがって、この２つの方程式を連立方程式として解くことによって、未知数である減衰比ζ及び固有振動数ωｎを同定することができる。 When two sets of relationship data of measured regenerative chatter frequency and spindle rotational speed are stored in the data storage unit 4, the damping ratio ζ and the natural frequency ω n of the vibration system are regarded as unknowns according to equation 18 or equation 21. The following two equations are obtained. Therefore, by solving these two equations as simultaneous equations, the unknown damping ratio ζ and natural frequency ω n can be identified.

尚、前記データ記憶部４に３組以上の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、算出部５は、以下の第３の態様又は第４の態様によって、減衰比ζ及び固有振動数ωｎを同定するのが好ましい。 When three or more sets of measured and reproduced chatter frequency ω c and data related to the spindle rotational speed S are stored in the data storage unit 4, the calculation unit 5 performs the third or fourth aspect described below. It is preferable to identify the damping ratio ζ and the natural frequency ω n .

［第３の態様］
算出部５は、前記データ記憶部４に２組以上の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、以下のようにして、前記振動系の減衰比ζ及び固有振動数ωｎを同定することができる。 [Third aspect]
When the relationship data of two or more sets of measured regenerative chatter frequency ω c and spindle rotational speed S is stored in the data storage unit 4, the calculation unit 5 calculates the damping ratio ζ of the vibration system as follows. The natural frequency ω n can be identified.

即ち、算出部５は、前記データ記憶部４に格納されたｐ番目の主軸回転速度Ｓｐ、及び工具ＴＬの刃数Ｎに基づき、上記数式１８又は数式２１にしたがって、前記振動系の固有振動数ωｎ及び減衰比ζをそれぞれ任意の値に設定して、設定したｍ番目の固有振動数ωｎｍ及び減衰比ζｍの組み合わせであるときの、各主軸回転速度Ｓｐのときの理論上の再生びびり周波数ω'ｃｐ,ｍをそれぞれ算出する。但し、ｐは１以上の整数であり、データ記憶部４に格納された関係データ、即ち、測定再生びびり周波数ωｃ及び主軸回転速度Ｓを対とするその組数ｑを最大値とする。また、ｍは１以上の整数であって、任意に設定される固有振動数ωｎ及び減衰比ζを対とするその組数を最大値とする。 That is, the calculation unit 5 performs the natural vibration of the vibration system according to the equation 18 or 21, based on the p-th main spindle rotational speed S p stored in the data storage unit 4 and the number N of blades of the tool TL. By setting the number ω n and the damping ratio ζ to arbitrary values, and theoretically combining the m-th natural frequency ω nm and the damping ratio ζ m , the respective spindle rotational speeds S p theoretically The reproduction chatter frequency ω ′ cp, m is calculated respectively. However, p is an integer of 1 or more, and the relationship data stored in the data storage unit 4, that is, the number q of sets of the measured reproduction chatter frequency ω c and the spindle rotational speed S as a pair is set as the maximum value. Further, m is an integer of 1 or more, and the number of pairs of the natural frequency ω n and the damping ratio ζ set arbitrarily is set as the maximum value.

尚、減衰比ζは経験上想定し得る範囲内で設定し、本例では、０．０１≦ζ≦０．０８の範囲で、０．００１刻みに設定した。また、固有振動数ωｎの設定範囲は、各主軸回転速度Ｓｐに対して、以下の数式２２で決定される範囲内で、１Ｈｚ刻みに設定した。したがって、設定される減衰比ζと固有振動数ωｎとの組み合わせは、それぞれが採り得る範囲内での全ての組み合わせであり、その組み合わせ個数は、（減衰比ζの設定個数）×（固有振動数ωの設定個数）となる。 The damping ratio ζ was set within a range that can be assumed empirically, and in this example, was set in 0.001 increments within the range of 0.01 ≦ ζ ≦ 0.08. The setting range of the natural frequency omega n, for each spindle rotational speed S p, to the extent determined by the following equation 22 was set to increments of 1 Hz. Therefore, the combination of the damping ratio ζ and the natural frequency ω n to be set is all combinations within the range that can be taken, and the number of combinations is (number of setting of damping ratio)) × (natural vibration) The set number of numbers ω)).

Figure 0006505145
Figure 0006505145

但し、ｋは、詳しくは後述する安定限界線図における安定ポケットの次数を意味し、下記数式２３によって算出される。尚、数式２３におけるωｃｐは、主軸回転速度Ｓｐのときの測定再生びびり周波数である。 However, k means the order of the stable pocket in the stable limit diagram described later in detail, and is calculated by the following equation 23. Incidentally, omega cp in Equation 23 is determined regenerative chatter frequency when the spindle rotational speed S p.

Figure 0006505145
Figure 0006505145

そして、算出部５は、前記固有振動数ωｎｍ及び減衰比ζｍの各設定値ごとに、測定再生びびり周波数ωｃｐと理論再生びびり周波数ω'ｃｐ,ｍとの差分の２乗和Ｊｍを下式数式２４によって算出する。 The calculation unit 5, the natural frequency omega nm and for each set value of damping ratio zeta m, measured regenerative chatter frequency omega cp and theoretical regenerative chatter frequency omega 'cp, 2 sum J m of the difference between m Is calculated by the following equation (24).

Figure 0006505145
Figure 0006505145

ついで、算出部５は、得られた２乗和Ｊｍが最小値となる固有振動数ωｎｍ及び減衰比ζｍを前記振動系の固有振動数ωｎ及び減衰比ζとして同定する。 Then, the calculation unit 5, the square sum J m obtained to identify natural frequency omega nm and damping ratio zeta m having a minimum value as a natural frequency omega n and damping ratio zeta of the vibration system.

［第４の態様］
算出部５は、前記データ記憶部４に２組以上の測定再生びびり周波数ωｃ及び主軸回転速度Ｓの関係データが格納されている場合、以下の態様によって、前記振動系の減衰比ζ及び固有振動数ωｎを同定することができる。 [Fourth aspect]
When the relationship data of two or more sets of measurement reproduction chatter frequency ω c and spindle rotational speed S is stored in the data storage unit 4, the calculation unit 5 determines the damping ratio ζ and the characteristic of the vibration system according to the following mode. The frequency ω n can be identified.

即ち、算出部５は、前記データ記憶部４に格納されたｐ番目の測定再生びびり周波数ωｃｐ、及び工具ＴＬの刃数Ｎに基づき、上記数式１８又は数式２１にしたがって、前記振動系の固有振動数ωｎ及び減衰比ζをそれぞれ任意の値に設定して、設定したｍ番目の固有振動数ωｎｍ及び減衰比ζｍの組み合わせであるときの、各測定再生びびり周波数ωｃｐのときの理論上の主軸回転速度Ｓ'ｐ,ｍをそれぞれ算出する。但し、ｐは１以上の整数であり、データ記憶部４に格納された関係データ、即ち、測定再生びびり周波数ωｃ及び主軸回転速度Ｓを対とするその組数ｑを最大値とする。また、ｍは１以上の整数であって、任意に設定される固有振動数ωｎ及び減衰比ζを対とするその組数を最大値とする。尚、本例では、減衰比ζと固有振動数ωとの組み合わせは、上述した第３の態様と同様とする。 That is, the calculation unit 5 is based on the p-th measurement reproduction chatter frequency ω cp stored in the data storage unit 4 and the number N of the tools TL, according to the equation 18 or 21, the uniqueness of the vibration system The frequency ω n and the damping ratio ζ are set to arbitrary values, and the m-th natural frequency ω nm and the damping ratio ζ m are set in combination at each measured reproduction chatter frequency ω cp The theoretical spindle rotational speed S ' p, m is calculated respectively. However, p is an integer of 1 or more, and the relationship data stored in the data storage unit 4, that is, the number q of sets of the measured reproduction chatter frequency ωc and the spindle rotational speed S as a pair is set as the maximum value. Further, m is an integer of 1 or more, and the number of pairs of the natural frequency ω n and the damping ratio ζ set arbitrarily is set as the maximum value. In the present example, the combination of the damping ratio ζ and the natural frequency ω is the same as that in the third aspect described above.

そして、算出部５は、前記固有振動数ωｎｍ及び減衰比ζｍの各設定値ごとに、前記データ記憶部４に格納された実際の主軸回転速度Ｓｐと理論主軸回転速度Ｓ'ｐ,ｍとの差分の２乗和Ｊ'ｍを下式数式２５によって算出する。 Then, the calculation unit 5 calculates the actual main spindle rotational speed Sp and the theoretical main spindle rotational speed S ′ p stored in the data storage unit 4 for each set value of the natural frequency ω nm and the damping ratio ζ m . The sum of squares J ′ m of the difference with m is calculated by the following formula 25.

Figure 0006505145
Figure 0006505145

ついで、算出部５は、得られた２乗和Ｊ'ｍが最小値となる固有振動数ωｎｍ及び減衰比ζｍを前記振動系の固有振動数ωｎ及び減衰比ζとして同定する。 Then, the calculation unit 5, the sum of squares J 'm that was obtained to identify the natural frequency omega nm and damping ratio zeta m having a minimum value as a natural frequency omega n and damping ratio zeta of the vibration system.

前記線図作成部６は、上記のようにして前記算出部５により同定された前記振動系の固有振動数ωｎ及び減衰比ζを用いて、以下の数式２６により、再生びびりを生じる境界となる限界（最大）切り込み深さａｐｌｉｍであって、主軸回転速度に応じた限界切り込み深さａｐｌｉｍを算出して安定限界線図を作成する。 The diagram creation unit 6 uses the natural frequency ω n and the damping ratio 同 定 of the vibration system identified by the calculation unit 5 as described above, and the boundary causing the reproduction chatter according to the following equation 26: The stability limit diagram is created by calculating the limit cut depth a plim corresponding to the spindle rotational speed with the limit (maximum) cut depth a plim .

Figure 0006505145
Figure 0006505145

尚、数式２６は、上述した数式１０をそれぞれの再生びびり周波数について解いて、対応する振動系の固有振動数ωｎ及び限界切り込み深さａｐｌｉｍを算出することにより得られる。 Formula 26 is obtained by solving Formula 10 described above for each reproduction chatter frequency and calculating the natural frequency ω n and the limit cut depth a plim of the corresponding vibration system.

上述した安定限界線図は、再生びびりを生じる不安定領域と再生びびりを生じない安定領域との境界を示す線図であって、主軸回転速度Ｓと工具の限界切り込み深さａｐｌｉｍとの相関を示す線図であり、例えば、図４に示すような線図として表される。同図４に示すように、工具の限界切り込み深さがピーク（極大値）を示す主軸転速度が複数存在し、各ピークを示す山形部は安定ポケットと称される。そして、最も高い主軸回転速度は、振動系の固有振動数ωｎを工具の刃数で除した回転速度で１次安定ポケットと称し、この主軸回転速度を順次大きい整数（２，３・・・）で除した主軸回転速度に対応する安定ポケットを、２次安定ポケット、３次安定ポケット・・・と称する。安定限界線図は、安定ポケットが高次になるほどその幅が狭まるという特徴を有する。 The above-mentioned stability limit diagram is a diagram showing the boundary between the unstable region causing regeneration chatter and the stable region not causing regeneration chatter, and the correlation between the spindle rotational speed S and the limit cutting depth a plim of the tool And is represented, for example, as a diagram as shown in FIG. As shown in FIG. 4, there are a plurality of spindle rotation speeds at which the limit cutting depth of the tool shows a peak (maximum value), and the chevrons showing each peak are called stable pockets. The highest spindle rotational speed is called the primary stable pocket in terms of the rotational speed obtained by dividing the natural frequency ω n of the vibration system by the number of blades of the tool, and this spindle rotational speed is sequentially increased by an integer (2, 3 ... The stable pockets corresponding to the spindle rotational speed divided by) are referred to as secondary stable pockets, tertiary stable pockets, and so on. The stability limit diagram is characterized in that the higher the stability pocket, the narrower the width.

そして、前記線図作成部６は、作成した安定限界線図の各安定ポケット付近において、各安定ポケットの頂点に対応した主軸回転速度をＳ(min−１)、算出された前記固有振動数をωｎ(Hz)、前記工具の刃数をＮとして下式数式２７によって整数ｋを算出するとともに、算出した整数ｋの値を対応する安定ポケット付近に配置した安定限界線図を作成するように構成される（図４参照）。

Figure 0006505145
但し、［］はガウス記号である。 Then, in the vicinity of each stable pocket of the created stability limit diagram, the diagram creating unit 6 sets the spindle rotational speed corresponding to the top of each stable pocket to S (min −1 ), and the calculated natural frequency ω n (Hz), where the number of cutting edges of the tool is N, the integer k is calculated by the following equation 27 and a stability limit diagram is created in which the calculated value of the integer k is arranged near the corresponding stability pocket Configured (see FIG. 4).
Figure 0006505145
 However, [] is a Gaussian symbol.

また、前記表示装置７は、適宜ディスプレイを備えており、前記線図作成部６から送信された安定限界線図に係る画像を前記ディスプレイ上に表示する。   In addition, the display device 7 appropriately includes a display, and displays an image according to the stability limit diagram transmitted from the diagram creating unit 6 on the display.

以上のように構成された本例の安定限界線図作成装置１によれば、前記工作機械２０によってワークＷが加工されると、その間に、工具ＴＬ、該工具ＴＬを保持する工具ホルダＴＨ、ワーク固定用治具ＷＪ及び工作機械２０によって構成される振動系の振動が加速度センサ２によって検出されるとともに、検出された振動に係る信号がびびり検出部３によって解析され、再生びびりが生じたときには、そのときの振動周波数が測定再生びびり周波数として、前記工作機械２０から取得される主軸回転速度に関連付けられて、前記データ記憶部４に格納される。   According to the stability limit diagram drawing device 1 of this example configured as described above, when the workpiece W is processed by the machine tool 20, the tool TL, the tool holder TH for holding the tool TL, and The vibration of the vibration system constituted by the workpiece fixing jig WJ and the machine tool 20 is detected by the acceleration sensor 2 and the signal relating to the detected vibration is analyzed by the chatter detection unit 3 and the regeneration chatter occurs The vibration frequency at that time is stored in the data storage unit 4 in association with the spindle rotational speed acquired from the machine tool 20 as the measurement reproduction chatter frequency.

そして、前記算出部５は、例えば、外部からの処理開始信号を受信して処理を開始し、前記データ記憶部４に格納された測定びびり周波数ωｃ及び主軸回転速度Ｓに係るデータを確認して、測定びびり周波数ωｃ及び主軸回転速度Ｓに係るデータが１組のみ格納されている場合には、上述した第１の態様により前記振動系の固有振動数ωｎ及び減衰比ζを同定し、測定びびり周波数ωｃ及び主軸回転速度Ｓに係るデータが２組格納されている場合には、上述した第２の態様、第３の態様又は第４の態様のいずれかによって前記固有振動数ωｎ及び減衰比ζを同定し、測定びびり周波数ωｃ及び主軸回転速度Ｓに係るデータが３組以上格納されている場合には、上述した第３の態様又は第４の態様によって前記固有振動数ωｎ及び減衰比ζを同定する。 Then, for example, the calculation unit 5 receives a process start signal from the outside and starts the process, and confirms the data related to the measured chatter frequency ω c and the spindle rotational speed S stored in the data storage unit 4 In the case where only one set of data concerning the measured chatter frequency ω c and the spindle rotational speed S is stored, the natural frequency ω n and the damping ratio ζ of the vibration system are identified according to the first aspect described above. When two sets of data relating to the measured chatter frequency ω c and the spindle rotational speed S are stored, the natural frequency ω is obtained according to any of the second aspect, the third aspect or the fourth aspect described above. When the n and the damping ratio 同 定 are identified, and three or more sets of data relating to the measured chatter frequency ω c and the spindle rotational speed S are stored, the natural frequency is determined according to the third aspect or the fourth aspect described above ω n and identify ζ damping ratio That.

そして、算出部５によって前記振動系の固有振動数ωｎ及び減衰比ζが同定されると、同定された固有振動数ωｎ及び減衰比ζを基に、線図作成部６によって、再生びびりを生じる境界となる限界切り込み深さａｐｌｉｍであって、主軸回転速度Ｓに応じた限界切り込み深さａｐｌｉｍを示す安定限界線図が作成されるとともに、その各安定ポケット付近に、当該安定ポケットの次数を示す整数ｋの値を配置した安定限界線図が作成される。そして、線図作成部６によって作成された安定限界線図が前記表示装置７に表示される。 Then, when the natural frequency ω n and the damping ratio ζ of the vibration system are identified by the calculation unit 5, the diagram creation unit 6 reproduces chatter based on the identified natural frequency ω n and the damping ratio ζ. a limit depth of cut a plim of the resulting boundary, along with the stability limit diagram indicates the limit depth of cut a plim corresponding to spindle rotational speed S is created, in the vicinity of each of its stable pockets, which stabilizing pockets A stability limit diagram is created in which values of integer k indicating the order of. Then, the stability limit diagram created by the diagram creation unit 6 is displayed on the display unit 7.

斯くして、この安定限界線図作成装置１によれば、工具ＴＬ、該工具ＴＬを保持する工具ホルダＴＨ、ワーク固定用治具ＷＪ及び工作機械２０によって構成される振動系全体に係る固有振動数ωｎ及び減衰比ζを同定して安定限界線図を作成するようにしているので、工具のみの固有振動数を基に安定限界線図を作成する従来に比べて、実際の加工に即したより現実的な安定限界線図を作成することができる。 Thus, according to the stability limit diagram drawing device 1, the natural vibration related to the whole vibration system constituted by the tool TL, the tool holder TH for holding the tool TL, the workpiece fixing jig WJ and the machine tool 20 Since the stability limit diagram is created by identifying the number ω n and the damping ratio 、, compared to the conventional method of creating the stability limit diagram based on the natural frequency of only the tool, it is more immediate to the actual processing It is possible to create a more realistic stability limit diagram.

そして、得られた安定限界線図を表示装置７に表示するようにしているので、オペレータは、このような実加工に即した安定限界線図を確認することで、再生びびりが生じない効率の良い、実加工に即した適正な加工条件を瞬時に理解することができる。   Then, since the obtained stability limit diagram is displayed on the display device 7, the operator confirms the stability limit diagram in line with such actual processing, so that the efficiency at which reproduction chatter does not occur is caused. Good, you can instantly understand the appropriate processing conditions in line with actual processing.

また、各安定ポケットに対応した次数ｋの値を対応する安定ポケットの付近に表示するようにしているので、オペレータは、各安定ポケットの次数を容易に理解することができる。   In addition, since the value of the order k corresponding to each stable pocket is displayed in the vicinity of the corresponding stable pocket, the operator can easily understand the order of each stable pocket.

以上、本発明の実施形態に係る安定限界線図作成装置１について説明したが、本発明の採り得る態様は、何ら上例のものに限定されるものではない。   As mentioned above, although the stability-limit-diagram creation apparatus 1 which concerns on embodiment of this invention was demonstrated, the aspect which this invention can take is not limited to the thing of an above example at all.

例えば、上述した第３の態様では、測定再生びびり周波数ωｃｐと理論再生びびり周波数ω'ｃｐ,ｍとの差分の２乗和Ｊｍを算出し、得られた２乗和Ｊｍが最小値となる固有振動数ωｎｍ及び減衰比ζｍを振動系の固有振動数ωｎ及び減衰比ζとして同定するようにしたが、これに限られるものではなく、この他、差の絶対値を積算する、差の４乗和を取る、或いは差の６乗和を取るなど、差を正の数として積算した値が最小値を示す固有振動数ωｎｍ及び減衰比ζｍを振動系の固有振動数ωｎ及び減衰比ζとして同定するようにしても良い。 For example, in the third aspect described above, the measurement regenerative chatter frequency omega cp and theoretical regenerative chatter frequency omega 'cp, calculates the square sum J m of the difference between m, resulting square sum J m is the minimum value The natural frequency ω nm and the damping ratio ζ m are identified as the natural frequency ω n and the damping ratio ζ of the vibration system, but the invention is not limited thereto, and in addition to this, the absolute value of the difference is integrated The natural frequency ω nm and the damping ratio ζ m at which the value integrated as the difference is a positive number, such as taking the fourth sum of differences or taking the sixth sum of differences It may be identified as the number ω n and the damping ratio ζ.

同様に、上述した第４の態様では、実際の主軸回転速度Ｓｐと理論主軸回転速度Ｓ'ｐ,ｍとの差分の２乗和Ｊ'ｍを算出し、得られた２乗和Ｊ'ｍが最小値となる固有振動数ωｎｍ及び減衰比ζｍを振動系の固有振動数ωｎ及び減衰比ζとして同定するようにしたが、これに限られるものではなく、差の絶対値を積算する、差の４乗和を取る、或いは差の６乗和を取るなど、差を正の数として積算した値が最小値を示す固有振動数ωｎｍ及び減衰比ζｍを振動系の固有振動数ωｎ及び減衰比ζとして同定するようにしても良い。 Similarly, in the fourth aspect described above, the sum of squares J ' m of the difference between the actual main spindle rotational speed S p and the theoretical main spindle rotational speed S' p, m is calculated, and the obtained sum of squares J ' Although the natural frequency ω nm and the damping ratio と なる m at which m is the minimum value are identified as the natural frequency ω n and the damping ratio 振動 of the vibration system, the present invention is not limited thereto. A natural frequency ω nm and an attenuation ratio ζ m at which the value obtained by integrating the difference as a positive number, such as integrating, taking the fourth sum of differences or taking the sixth sum of differences It may be identified as the frequency ω n and the damping ratio ζ.

また、前記第３の態様及び第４の態様において、任意に設定される減衰比ζ及び固有振動数ωｎの設定範囲は、上例のものに限られるものでは無く、適宜妥当な範囲に設定することができ、また、その設定間隔も適宜他の間隔を採用することができる。 Further, in the third aspect and the fourth aspect, the setting ranges of the damping ratio ζ and the natural frequency ω n which are arbitrarily set are not limited to those in the above example, and are appropriately set to appropriate ranges. Also, the setting interval may be other intervals as appropriate.

また、上例では、加速度センサ２によって振動系の振動を検出するようにしたが、振動を検出する手段はこれに限られるものではなく、マイクロフォンなど他の検出装置を適用することができる。   In the above example, the vibration of the vibration system is detected by the acceleration sensor 2. However, the means for detecting the vibration is not limited to this, and other detection devices such as a microphone can be applied.

また、工作機械２０の構成や使用する工具ＴＬについても、何ら上例のものに限定されるものではない。   Further, the configuration of the machine tool 20 and the tool TL to be used are not limited to those described above.

１ 安定限界線図作成装置
２ 加速度センサ
３ びびり検出部
４ データ記憶部
５ 算出部
６ 線図作成部
７ 表示装置
２０ 工作機械
２４ 主軸
２５ テーブル
ＴＨ 工具ホルダ
ＴＬ 工具
ＷＪ ワーク固定用治具
Ｗ ワーク 1 stability limit diagram drawing device 2 acceleration sensor 3 chatter detection unit 4 data storage unit 5 calculation unit 6 diagram drawing unit 7 display device 20 machine tool 24 spindle 25 table TH tool holder TL tool WJ jig for workpiece fixing W workpiece

Claims (7)

少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成装置であって、
前記再生びびりの周波数と前記主軸回転速度との関係を記憶するデータ記憶部と、
前記工具が装着される付近に配置され、該工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出する振動検出部と、
前記振動検出部によって検出された振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、該再生びびりの周波数を測定再生びびり周波数として、該再生びびりが生じたときの前記主軸回転速度と関連付けて前記データ記憶部に格納するびびり検出部と、
前記工具、前記工具ホルダ、前記ワーク固定用治具及び前記工作機械の組み合わせに基づいて任意に設定した前記振動系の減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記振動系の固有振動数を算出する算出部と、
前記算出部により算出された固有振動数、前記設定した減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて、前記安定限界線図を作成する線図作成部と、
当該線図作成部により作成された前記安定限界線図を表示する表示部とを備えることを特徴とする安定限界線図作成装置。 The stability region and instability of the regenerative chatter, the value of which varies according to the natural frequency and damping ratio of the vibration system that differs depending on the combination of at least the tool used, the tool holder holding the tool, the work fixing jig and the machine tool A stability limit diagram drawing device for producing a stability limit diagram, which is a correlation diagram of a spindle rotation speed and a limit cutting depth of the tool, showing a boundary with a region,
A data storage unit for storing the relationship between the frequency of the reproduction chatter and the spindle rotational speed;
A vibration detection unit disposed in the vicinity where the tool is mounted and detecting the magnitude and frequency of the vibration of the vibration system generated when a workpiece is machined using the tool;
Based on the magnitude of vibration detected by the vibration detection unit, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is determined. A chatter detection unit which is stored as the measurement playback chatter frequency in the data storage unit in association with the spindle rotational speed when the playback chatter occurs;
Damping ratio of the vibration system arbitrarily set based on the combination of the tool, the tool holder, the jig for fixing the work, and the machine tool, and the measurement reproduction chatter frequency and the spindle stored in the data storage unit A calculation unit that calculates the natural frequency of the vibration system based on the rotational speed;
A diagram for creating the stability limit diagram based on the natural frequency calculated by the calculation unit, the set attenuation ratio, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit. The creation department,
And a display unit for displaying the stability limit diagram created by the diagram creation unit. 少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成装置であって、
前記再生びびりの周波数と前記主軸回転速度との関係を記憶するデータ記憶部と、
前記工具が装着される付近に配置され、該工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出する振動検出部と、
前記振動検出部によって検出された振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、該再生びびりの周波数を測定再生びびり周波数として、該再生びびりが生じたときの前記主軸回転速度と関連付けて前記データ記憶部に格納するびびり検出部と、
前記データ記憶部に格納されたデータを確認し、複数組の前記測定再生びびり周波数と前記主軸回転速度との関係データが格納されている場合には、該複数組の前記測定再生びびり周波数と前記主軸回転速度との関係データに基づいて、前記振動系の減衰比及び固有振動数を算出する算出部と、
前記算出部により算出された固有振動数、減衰比、並びに前記データ記憶部に格納された前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記安定限界線図を作成する線図作成部と、
前記線図作成部により作成された前記安定限界線図を表示する表示部と、
を備えることを特徴とする安定限界線図作成装置。 The stability region and instability of the regenerative chatter, the value of which varies according to the natural frequency and damping ratio of the vibration system that differs depending on the combination of at least the tool used, the tool holder holding the tool, the work fixing jig and the machine tool A stability limit diagram drawing device for producing a stability limit diagram, which is a correlation diagram of a spindle rotation speed and a limit cutting depth of the tool, showing a boundary with a region,
A data storage unit for storing the relationship between the frequency of the reproduction chatter and the spindle rotational speed;
A vibration detection unit disposed in the vicinity where the tool is mounted and detecting the magnitude and frequency of the vibration of the vibration system generated when a workpiece is machined using the tool;
Based on the magnitude of vibration detected by the vibration detection unit, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is determined. A chatter detection unit which is stored as the measurement playback chatter frequency in the data storage unit in association with the spindle rotational speed when the playback chatter occurs;
The data stored in the data storage unit is confirmed, and when the relationship data between a plurality of sets of the measurement reproduction chatter frequency and the spindle rotational speed is stored, the plurality of sets of the measurement reproduction chatter frequency and the relationship A calculation unit that calculates the damping ratio and the natural frequency of the vibration system based on the relationship data with the spindle rotational speed;
A diagram creation unit that creates the stability limit diagram based on the natural frequency and the damping ratio calculated by the calculation unit, and the measurement reproduction chatter frequency and the spindle rotational speed stored in the data storage unit;
A display unit for displaying the stability limit diagram created by the diagram creation unit;
A stability limit diagram drawing device characterized by comprising. 前記算出部は、前記振動系の固有振動数及び減衰比をそれぞれ任意の複数の値に設定し、各設定値について、所定式で表わされる前記再生びびり周波数、主軸回転速度、固有振動数及び減衰比との関係を基に、前記データ記憶部に記憶された複数の主軸回転速度に対応した理論再生びびり周波数をそれぞれ算出し、各設定値ごとに、前記各主軸回転速度に対応する前記理論再生びびり周波数と前記測定再生びびり周波数との差をそれぞれ算出して積算し、積算された差が最小値を示す前記設定値を、前記振動系の減衰比及び固有振動数として同定するように構成されていることを特徴とする請求項２記載の安定限界線図作成装置。   The calculation unit sets the natural frequency and the damping ratio of the vibration system to a plurality of arbitrary values, and for each set value, the regenerative chatter frequency, the spindle rotational speed, the natural frequency and the damping represented by a predetermined formula The theoretical reproduction chatter frequency corresponding to the plurality of spindle rotational speeds stored in the data storage unit is calculated based on the relationship with the ratio, and the theoretical reproduction corresponding to the respective spindle rotational speeds is calculated for each setting value. The difference between chatter frequency and the measurement reproduction chatter frequency is respectively calculated and integrated, and the set value indicating the minimum value of the accumulated difference is configured to be identified as the damping ratio and the natural frequency of the vibration system. The stability limit diagram drawing device according to claim 2, characterized in that: 前記算出部は、前記振動系の固有振動数及び減衰比をそれぞれ任意の複数の値に設定し、各設定値について、所定式で表わされる前記再生びびり周波数、主軸回転速度、固有振動数及び減衰比との関係を基に、前記データ記憶部に記憶された複数の測定再生びびり周波数に対応した理論主軸回転速度をそれぞれ算出し、各設定値ごとに、前記各測定再生びびり周波数に対応する前記理論主軸回転速度と前記データ記憶部に格納された主軸回転速度との差をそれぞれ算出して積算し、積算された差が最小値を示す前記設定値を、前記振動系の減衰比及び固有振動数として同定するように構成されていることを特徴とする請求項２記載の安定限界線図作成装置。   The calculation unit sets the natural frequency and the damping ratio of the vibration system to a plurality of arbitrary values, and for each set value, the regenerative chatter frequency, the spindle rotational speed, the natural frequency and the damping represented by a predetermined formula Based on the relationship with the ratio, theoretical spindle rotational speeds corresponding to the plurality of measurement reproduction chatter frequencies stored in the data storage unit are respectively calculated, and for each setting value, the above-mentioned measurement resistance corresponding to each measurement reproduction chatter frequency The difference between the theoretical spindle rotational speed and the spindle rotational speed stored in the data storage unit is calculated and integrated, and the setting value indicating the minimum value of the accumulated difference is the damping ratio and the natural vibration of the vibration system. The stability limit diagram drawing device according to claim 2, characterized in that it is configured to be identified as a number. 前記線図作成部は、作成した前記安定限界線図の各安定ポケットの頂点に対応した主軸回転速度をＳ(min−１)、算出された前記固有振動数をωｎ(Hz)、前記工具の刃数をＮとして下式によって整数ｋを算出するとともに、算出した整数ｋの値を対応する安定ポケット付近に配置した安定限界線図を作成するように構成されていることを特徴とする請求項１乃至４記載のいずれかの安定限界線図作成装置。
Figure 0006505145
 但し、［］はガウス記号である。 The diagram creation unit sets the spindle rotational speed corresponding to the top of each stable pocket of the created stability limit diagram to S (min −1 ), the calculated natural frequency ω n (Hz), and the tool While calculating the integer k according to the following equation, where N is the number of blades, it is configured to create a stability limit diagram in which the value of the calculated integer k is arranged near the corresponding stability pocket. Item 4. The stability limit diagram drawing device according to any one of Items 1 to 4.
Figure 0006505145
 However, [] is a Gaussian symbol. 少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成方法であって、
前記工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出し、
検出した前記振動系の振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、当該再生びびりの周波数を、測定再生びびり周波数として該再生びびりが生じたときの前記主軸回転速度と関連付けて記憶し、
前記工具、前記工具ホルダ、前記ワーク固定用治具及び前記工作機械の組み合わせに基づいて任意に設定した前記振動系の減衰比、並びに記憶した前記測定再生びびり周波数及び前記主軸回転速度に基づいて前記振動系の固有振動数を算出し、算出した固有振動数、前記設定した減衰比、並びに記憶した前記測定再生びびり周波数及び前記主軸回転速度に基づいて、前記安定限界線図を作成するようにしたことを特徴とする安定限界線図作成方法。 The stability region and instability of the regenerative chatter, the value of which varies according to the natural frequency and damping ratio of the vibration system that differs depending on the combination of at least the tool used, the tool holder holding the tool, the work fixing jig and the machine tool A stability limit diagram drawing method for producing a stability limit diagram, which is a correlation diagram between a spindle rotation speed and a limit cutting depth of the tool, which shows a boundary with a region,
Detecting the magnitude and frequency of the vibration of the vibration system generated when processing a workpiece using the tool;
Based on the detected magnitude of vibration of the vibration system, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is measured Storing in association with the spindle rotational speed when the reproduction chatter occurs as a reproduction chatter frequency,
Based on the damping ratio of the vibration system arbitrarily set based on the combination of the tool, the tool holder, the jig for fixing the work and the machine tool, and based on the stored measured regenerative chatter frequency and the spindle rotational speed. The characteristic limit of the vibration system is calculated, and the stability limit diagram is created on the basis of the calculated characteristic frequency, the set attenuation ratio, and the stored measured regenerative chatter frequency and the spindle rotational speed. A method of creating a stability limit diagram characterized by 少なくとも使用する工具、該工具を保持する工具ホルダ、ワーク固定用治具及び工作機械の組み合わせによってその値が異なる振動系の固有振動数と減衰比に応じて変化する再生びびりの安定領域と不安定領域との境界を示す、主軸回転速度と前記工具の限界切り込み深さとの相関線図である安定限界線図を作成する安定限界線図作成方法であって、
前記工具を用いてワークを加工した際に生じる前記振動系の振動の大きさ及び周波数を検出し、
検出した前記振動系の振動の大きさを基に、前記工具に再生びびりが生じたかどうかを判別し、前記工具に再生びびりが生じたと判断された場合には、当該再生びびりの周波数を、測定再生びびり周波数として該再生びびりが生じたときの前記主軸回転速度と関連付けて記憶し、
記憶した前記測定再生びびり周波数と前記主軸回転速度との関係データが複数組ある場合には、該複数組の前記測定再生びびり周波数と前記主軸回転速度との関係データに基づいて、前記振動系の減衰比及び固有振動数を算出し、算出した固有振動数、減衰比、並びに記憶した前記測定再生びびり周波数及び前記主軸回転速度に基づいて、前記安定限界線図を作成するようにしたことを特徴とする安定限界線図作成方法。 The stability region and instability of the regenerative chatter, the value of which varies according to the natural frequency and damping ratio of the vibration system that differs depending on the combination of at least the tool used, the tool holder holding the tool, the work fixing jig and the machine tool A stability limit diagram drawing method for producing a stability limit diagram, which is a correlation diagram between a spindle rotation speed and a limit cutting depth of the tool, which shows a boundary with a region,
Detecting the magnitude and frequency of the vibration of the vibration system generated when processing a workpiece using the tool;
Based on the detected magnitude of vibration of the vibration system, it is determined whether or not regenerative chatter has occurred in the tool, and if it is determined that regenerative chatter has occurred in the tool, the frequency of the regenerative chatter is measured Storing in association with the spindle rotational speed when the reproduction chatter occurs as a reproduction chatter frequency,
In the case where there are a plurality of sets of relationship data between the stored measured regenerative chatter frequency and the spindle rotational speed, the plurality of sets of the measured regenerative chatter frequency and the spindle rotational speed are based on the data of the vibration system. Damping ratio and natural frequency are calculated, and the stability limit diagram is created on the basis of the calculated natural frequency, damping ratio, and the stored measured regenerative chatter frequency and the spindle rotational speed. How to make the stability limit diagram.
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