JPS6213134B2 - - Google Patents

Description

【発明の詳細な説明】 本発明は切削工具の切削中における切刃の欠損
を監視する方法の改良に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for monitoring chipping of a cutting edge during cutting of a cutting tool.

従来切削中の工具のチツピング、欠損等の異常
現象のインプロセスの監視方法として知られてい
る方法に特別なセンサを用いない主電動機の電流
値、消費電力による方式、切削動力計による切削
抵抗の主分力の増加分による方式が試みられ或い
は工具内の亀裂の発生、伝ぱを試験できるといわ
れるAEセンサによる方法が研究されている。し
かしながら電流、電力、切削抵抗による方式は切
削条件の変化被削材の形状および回転振れなどの
影響をうけ工具損傷が発生したのと類似の信号が
出力する場合がある。またAEセンサによる方式
は稼動中の工作機械の機械要素からの音響放射お
よび切削中の切屑切断時の音響放射が工具損傷時
のAE信号に類似する場合があつて何れも工場現
場では機能が十分に発揮され難く、実用上には未
だ満足されるものではない。出願人は実用されう
る工具異常監視方法を見出すべく先に提案した特
公昭52―35154号をもとに切削の３分力（主分力
Fc、背分力Fn、送り分力Ft）及び２分力比
（Fn／Fc，Ft／Fc）の因子を用いた研究を更に
発展させた。即ち工具刃形、切削条件及び被削材
質の関係並びに前記が同じ場合、工具損傷の有無
によつて切削抵抗、切削分力比率にどのような変
化を生じるかを第３図の計測ブロツク線図で種々
に実験した。切削抵抗３分力Fc，Ft，Fnは工具
動力計―動ひづみ計の出力として記録計（または
記録計に代わり電圧計）に入力し、また２個の割
算器に入力されて、切削分力比率Ft／Fc，Fn／
Fcが演算され記録計に入力した。また旋盤主軸
の回転信号も近接スイツチにより検出し、記録計
に入力した。そして旋盤は直流電動機により必要
により一定切削速度がえられるようにした。 Conventionally known in-process monitoring methods for abnormal phenomena such as chipping and chipping of tools during cutting include methods based on the current value and power consumption of the main motor that do not use special sensors, and methods based on cutting resistance using a cutting dynamometer. A method using an increase in the principal component force has been tried, and a method using an AE sensor, which is said to be able to test the occurrence and propagation of cracks within a tool, is being researched. However, the method using current, electric power, and cutting resistance is affected by changes in cutting conditions, the shape of the workpiece, rotational runout, etc., and may output a signal similar to that of tool damage. In addition, with the AE sensor method, the acoustic radiation from the mechanical elements of the machine tool during operation and the acoustic radiation when cutting chips during cutting can be similar to the AE signal when the tool is damaged, so both functions are sufficient at the factory site. This is difficult to demonstrate, and is still unsatisfactory in practice. In order to find a practical tool abnormality monitoring method, the applicant proposed the three-component cutting force (principal force
We further developed the research using the factors of Fc, back force Fn, feed force Ft) and two-component force ratio (Fn/Fc, Ft/Fc). In other words, the measurement block diagram in Figure 3 shows how the cutting force and cutting force ratio change depending on the relationship between the tool edge shape, cutting conditions, and workpiece material, and when the above conditions are the same, depending on the presence or absence of tool damage. I conducted various experiments. The cutting resistance 3 component forces Fc, Ft, and Fn are input to a recorder (or a voltmeter instead of a recorder) as the output of the tool dynamometer-dynamic strain meter, and are also input to two dividers to calculate the cutting force. Force ratio Ft/Fc, Fn/
Fc was calculated and input into the recorder. The rotation signal of the lathe main shaft was also detected by a proximity switch and input into the recorder. The lathe was equipped with a DC motor to provide a constant cutting speed as required.

切削条件による切削抵抗、切削分力比率の変化
を実験した第４図のその切削条件での結果から切
削抵抗のうち背分力Fnは切削速度および切込み
が変化してもその絶対値はほとんど変化しない
が、主分力および送り分力は切削速度、切込みの
変化に対して比較的大きく変化する。 An experiment was conducted to examine changes in cutting resistance and cutting force ratio depending on cutting conditions. From the results under the cutting conditions shown in Figure 4, the absolute value of thrust force Fn of cutting resistance hardly changes even if the cutting speed and depth of cut change. However, the principal component force and the feed component force change relatively largely with changes in cutting speed and depth of cut.

第５図のその切削条件での結果（●〇印実験
値、実線と点線理論値以下同じ）から切削速度と
切削分力比率Ft／Fcは切削速度が大きくなるに
つれレベルが低下するが、切削分力比率Fn／Fc
は切削速度が変化してもレベルは殆んど変化しな
い。 The results under the cutting conditions in Fig. 5 (experimental values marked with ●〇, solid line and dotted line theoretical values are the same), the level of cutting speed and cutting force ratio Ft/Fc decreases as the cutting speed increases, but cutting Force ratio Fn/Fc
The level hardly changes even if the cutting speed changes.

第６図のその切削条件での結果から、送りと切
削分力比率Ft／Fcは送りが大きくなるとレベル
が低下するが切削分力比率Fn／Fcは殆ど変化し
ない。 From the results in FIG. 6 under the cutting conditions, the level of the feed and cutting force ratio Ft/Fc decreases as the feed increases, but the cutting force ratio Fn/Fc hardly changes.

第７図のその切削条件での結果から、切込みと
切削分力比率Ft／Fcは切込みが２mm以上ではほ
ぼ一定値に近い値であるが、Fn／Fcは顕著な変
化を示す。 From the results under the cutting conditions shown in FIG. 7, the depth of cut and cutting force ratio Ft/Fc are almost constant values when the depth of cut is 2 mm or more, but Fn/Fc shows a remarkable change.

第８図はその切削条件での結果からノーズ半径
と切削分力比率Ft／Fcはノーズ半径増大につれ
僅かに低くなる傾向を示すが、Fn／Fcは逆に僅
かに高くなる傾向を示す。 FIG. 8 shows that the nose radius and cutting force ratio Ft/Fc tend to decrease slightly as the nose radius increases, while Fn/Fc tends to increase slightly as the nose radius increases, based on the results under the cutting conditions.

第９図、第１０図のその切削条件での結果から
被削材質と切削分力比率Ft／Fcは材質の違いに
よるレベルにかなりの差がある。Fn／Fcはその
影響はかなり小さい。 From the results shown in FIGS. 9 and 10 under the cutting conditions, there are considerable differences in the level of the work material and the cutting force ratio Ft/Fc depending on the material. The effect on Fn/Fc is quite small.

以上の切削条件と切削分力比率関係において
Ft／Fcは種々の条件により影響をうけるが、
Fn／Fcは切込み以外の影響はほとんど受けない
ので切込みの関数として表すことができる。 In the above cutting conditions and cutting force ratio relationship,
Ft/Fc is affected by various conditions, but
Since Fn/Fc is hardly affected by anything other than the depth of cut, it can be expressed as a function of the depth of cut.

また全く損傷のない工具（Ta） 前切れ刃にチツピングがあり主切れ刃に損傷の
ない工具（Tb） 主切れ刃チツピングがあり前切れ刃に損傷のな
い工具（Tc） これ等の工具を用い、第１１図のその切削条件
に対する結果から、 工具Tbの場合、工具Taの場合と比較すると、
切削抵抗においては主分力Fcは147.0N、送り分
力Ftは73.5N、背分力Fnは533.1N増大し、背分力
Fnに顕著な変化がみられた。また切削分力比率
においてはFt／Fcはほとんど変化しないがFn／
Fcは約2.8倍の変化をした。工具Tcの場合、工具
Tcの場合と比較すると、切削抵抗においては主
分力Fcは147.0N、送り分力Ftは330.2N、背分力
Fnは22.5N増大し、送り分力Ftが顕著な変化を示
した。また切削分力比率においてはFt／Fcは約
1.6倍の変化を示すが、Fn／Fcはほとんど変化が
なかつた。これらのことから前切れ刃のチツピン
グに対しては背分力Fnまたは切削分力比率Fn／
Fcの増大傾向をとらえ、主切れ刃のチツピング
に対しては、送り分力Ftまたは切削分力比率
Ft／Fcの増大傾向をとられることによつてそれ
ぞれチツピングを検出することが可能と判断され
た。 Tools with no damage at all (Ta) Tools with chipping on the front cutting edge and no damage on the main cutting edge (Tb) Tools with chipping on the main cutting edge and no damage on the front cutting edge (Tc) Using these tools , From the results for the cutting conditions in Fig. 11, in the case of tool Tb, compared with the case of tool Ta,
Regarding cutting resistance, the principal force Fc increases by 147.0N, the feed force Ft increases by 73.5N, and the back force Fn increases by 533.1N.
Significant changes were observed in Fn. In addition, in the cutting force ratio, Ft/Fc hardly changes, but Fn/
Fc changed approximately 2.8 times. For tool Tc, tool
Compared to the case of Tc, in terms of cutting resistance, the principal force Fc is 147.0N, the feed force Ft is 330.2N, and the back force is 330.2N.
Fn increased by 22.5N, and the feed force Ft showed a remarkable change. Also, in terms of cutting force ratio, Ft/Fc is approximately
Although the change was 1.6 times, there was almost no change in Fn/Fc. From these facts, for chipping of the front cutting edge, the back force Fn or the cutting force ratio Fn/
Considering the increasing tendency of Fc, for chipping of the main cutting edge, feed component force Ft or cutting force ratio
It was determined that chipping could be detected by observing the increasing trend of Ft/Fc.

更に切削の継続が困難な状態の工具欠損の発生
にともなう現象の解析を実験し欠損を発生させる
ための被削材にスポツト溶接部を設け第１２図の
その切削条件に対する結果から、 切削開始からＡまでは通常の切削が行われ、切
削抵抗、切削分力比率ともに工具損傷のない場合
の値を示している。Ａ―Ｂ間では送り分力Ft及
び切削分力比率Ft／Fcが増大しはじめ、主切れ
刃にチツピングが発生したことが推定できた。こ
の間主分力Fc、背分力Fnおよび切削分力比率
Fn／Fcの変化はわずかである。Ｂ―Ｃ間では送
り分力Ftおよび切削分力比率Ft／Fcせさらに増
大し、Ft／Fcは100％ちかい値を示した。このこ
とから主切れ刃のチツピングがさらに大きくなり
主切れ刃の欠損が生じたものと判断された。一方
主分力Fc、背分力Fn、切削分力比率Fn／Fcも増
大をはじめ、前切れ刃にもチツピングが発生した
ことが推定できた。Ｃにおいて前切れ刃（刃先）
の欠損が発生したが欠損発生の直前においては、
正常切削時に比べると、主分力Fcは172.5N、送
り分力Ftは731.1N、背分力Fnは80.4増大し切削
分力比率Ft／Fcは66％、Fn／Fcは10％増大し
た。欠損発生から13ms後には欠損直前と比較す
ると主分力Fcは163.7N、送り分力Ftは334.2N、
切削分力比率Ft／Fcは18％減少するのに反し、
背分力Fnは646.8N、切削分力比率Fn／Fcは78％
増大した。 Furthermore, we conducted an experiment to analyze the phenomenon that occurs when tool breakage occurs when it is difficult to continue cutting, and we created spot welds on the workpiece material to cause the breakage, and based on the results for the cutting conditions shown in Figure 12, we determined that from the start of cutting. Up to A, normal cutting is performed, and both the cutting resistance and the cutting force ratio show values when there is no damage to the tool. Between A and B, the feed force Ft and the cutting force ratio Ft/Fc began to increase, indicating that chipping had occurred on the main cutting edge. During this time, principal force Fc, thrust force Fn, and cutting force ratio
Changes in Fn/Fc are slight. Between B and C, the feeding force Ft and the cutting force ratio Ft/Fc further increased, and Ft/Fc showed a value close to 100%. From this, it was determined that the chipping of the main cutting edge became even more severe and the chipping of the main cutting edge occurred. On the other hand, the principal force Fc, back force Fn, and cutting force ratio Fn/Fc began to increase, and it was assumed that chipping also occurred on the front cutting edge. Front cutting edge (cutting edge) at C
A defect occurred, but immediately before the defect occurred,
Compared to normal cutting, the principal force Fc increased by 172.5N, the feed force Ft increased by 731.1N, the back force Fn increased by 80.4, the cutting force ratio Ft/Fc increased by 66%, and Fn/Fc increased by 10%. 13ms after the defect occurred, the principal component force Fc was 163.7N, the feed component force Ft was 334.2N, compared to just before the defect.
Although the cutting force ratio Ft/Fc decreased by 18%,
Back force Fn is 646.8N, cutting force ratio Fn/Fc is 78%
It increased.

更にまた切削中に切削抵抗、切削分力比率が変
化すると考えられる形状の第１３図について実験
し、また前切れ刃（刃先）の欠損時に生じた急激
な変化に対処するため、第１図のように微分器を
加えて切削分力比率Fn／Fcの時間に対する正の
微係数ｄ（Fn／Fc）／dt、また空切削の影響を
除去するため、主分力Fcが設定値（本実験では
294Nとした）以上でのｄ（Fn／Fc）／dt（主分
力設定値＋微係数と記す）の変化についても検討
できるように第１４図の切削条件に対する結果か
ら 被削材WA：切削抵抗は被削材１回転の間に切
込みｄ＝１mmとｄ＝２mmの切削に相当する変化を
示し、切削分力比率はごくわずかな変化を示すの
みである。このため切削分力比率Fn／Fcの微係
数および（主分力設定値＋微係数）は定常切削時
と殆ど差がない。しかし切削抵抗の微係数は、か
なり変化するものと考えられた。 Furthermore, we experimented with the shape shown in Fig. 13, which is considered to have a shape in which the cutting resistance and cutting force ratio change during cutting, and in order to deal with the sudden change that occurred when the front cutting edge (cutting edge) broke, we conducted an experiment using the shape shown in Fig. 1. By adding a differentiator, the positive differential coefficient d(Fn/Fc)/dt of the cutting force ratio Fn/Fc with respect to time, and in order to remove the influence of idle cutting, the principal force Fc was set to the set value (in this experiment Well then
Based on the results for the cutting conditions in Figure 14, we can also examine the change in d(Fn/Fc)/dt (denoted as principal component force set value + differential coefficient) at 294N) or above.Workpiece material WA: Cutting The resistance shows a change corresponding to cutting at depths of cut d=1 mm and d=2 mm during one revolution of the workpiece, and the cutting force ratio shows only a slight change. Therefore, the differential coefficient and (principal force setting value + differential coefficient) of the cutting force ratio Fn/Fc have almost no difference from those during steady cutting. However, the differential coefficient of cutting force was considered to vary considerably.

被削材WB：切削抵抗は定常切削時の値と空切
削時の値（各切削抵抗は０）の間を変化し、この
ため切削分力比率Fn／Fcの微係数は定常切削か
ら空切削に移るとき大きな変化を示すが（主分力
設定値＋微係数）は主分力Fcの設定値の効果よ
りほとんど変化しない。 Work material WB: The cutting resistance changes between the value during steady cutting and the value during idle cutting (each cutting resistance is 0), so the differential coefficient of the cutting force ratio Fn/Fc changes from steady cutting to idle cutting. When moving to , it shows a large change, but (principal force setting value + differential coefficient) hardly changes compared to the effect of the setting value of principal component force Fc.

被削材WC：切削抵抗も切削分力比率も被削材
１回転の間に切込みｄ＝１〜２mmの切削に相当す
る変化を示す。これにより切削分力比率Fn／Fc
の微係数にはゆるやかな変化を生ずるが（主分力
設定値＋微係数）は変化しなくなつた。 Workpiece material WC: Both cutting resistance and cutting force ratio show changes corresponding to cutting with depth of cut d=1 to 2 mm during one rotation of the workpiece material. As a result, the cutting force ratio Fn/Fc
Although there was a gradual change in the differential coefficient of (principal force setting value + differential coefficient), it stopped changing.

被削材WD（＝WA＋WB）：切削抵抗はそれぞ
れの形状特性の和の形で変化するが、切削分力比
率は被削材WBの特性が強く、空切削時に割算器
の飽和値を示す。切削分力比率Fn／Fcの微係数
は被削材WBの場合とほぼ同じ変化を示すが（主
分力設定値＋微係数）は主分力Fcの設定値の効
果によりほとんど変化しなくなつた。 Work material WD (= WA + WB): Cutting force changes as the sum of each shape characteristic, but the cutting force ratio has strong characteristics of the work material WB, and shows the saturation value of the divider during dry cutting. . The differential coefficient of the cutting force ratio Fn/Fc shows almost the same change as in the case of the workpiece material WB, but (principal force setting value + differential coefficient) hardly changes due to the effect of the setting value of principal component force Fc. Ta.

被削材WE（＝WA＋WB＋WC）：切削抵抗は
それぞれの形状特性の和として変化するが、切削
分力比率には被削材WBと被削材WCの特性がよ
くあらわれている。被削材WCの形状特性により
切削分力比率Fn／Fcの微係数はやや小さくなつ
ているが、空切削時には大きな変化を示す。しか
し主分力Fcの設定値の効果のため（主分力設定
値＋微係数）はほとんど変化しない。 Work material WE (=WA + WB + WC): Although the cutting resistance changes as the sum of the shape characteristics of each, the characteristics of the work material WB and work material WC are well expressed in the cutting force ratio. Although the differential coefficient of the cutting force ratio Fn/Fc is somewhat small due to the shape characteristics of the workpiece material WC, it shows a large change during dry cutting. However, due to the effect of the set value of the principal component force Fc, (principal force set value + differential coefficient) hardly changes.

被削材WF：空切削と実切削を繰り返しながら
徐々に定常切削になり、切削抵抗も切削分力比率
も変動しながら定常値に到達する。切削分力比率
Fn／Fcの微係数は、これまでと同じく実切削か
ら空切削になるとき大きく変化するが（主分力設
定値＋微係数）には変化がみられない。 Work material WF: Gradually becomes steady cutting while repeating dry cutting and actual cutting, and the cutting force and cutting force ratio reach steady values while fluctuating. Cutting force ratio
As before, the differential coefficient of Fn/Fc changes greatly when going from actual cutting to idle cutting, but no change is observed in (principal force setting value + differential coefficient).

被削材WG：定常切削から空切削に移るとき、
ばりの影響のため切削抵抗は徐々に低下する。特
に背分力Fnは他の２分力よりもゆるやかな減少
傾向を示す。このため、切削分力比率Ft／Fcは
定常値から約0.2秒後に空切削の値に到達するが
切削分力比率Fn／Fcは定常切削時よりも高い値
を約0.5秒継続しながら空切削時の値に到達す
る。切削分力比率の微係数は定常切削時とほとん
ど差がない。 Work material WG: When moving from steady cutting to idle cutting,
The cutting force gradually decreases due to the influence of burrs. In particular, the thrust force Fn shows a slower decreasing tendency than the other two component forces. For this reason, the cutting force ratio Ft/Fc reaches the value for dry cutting after about 0.2 seconds from the steady value, but the cutting force ratio Fn/Fc continues to maintain a value higher than during steady cutting for about 0.5 seconds while dry cutting. Reach the value of the hour. The differential coefficient of the cutting force ratio has almost no difference from that during steady cutting.

以上のように、被削材形状によつて切削抵抗、
切削分力比率およびこれらの微係数がかなり変化
することが示唆された。 As mentioned above, cutting resistance depends on the shape of the workpiece.
It is suggested that the cutting force ratios and their derivatives vary considerably.

このように被削材形状によつて損耗が発生した
のと同様の現象が生ずることが判明したので、切
削条件、被削材形状の影響を除去するために切削
抵抗がそれぞれ設定値以上の値でなければ検出条
件を満たさないこと、切削中の切削分力比率が設
定値（摩耗判定基準）以上の値を一定時間（例え
ば１〜1.2sec）継続した場合に逃げ面摩耗の検出
信号を出すことにして空切削や被削材WGのよう
なばりを生ずる被削材に対しても安定した工具摩
耗検出できるように考慮し、切刃のチツピング状
態においては引続き切削が可能で必ずしも早急な
機械停止は必要ないが切刃の大きな欠け及びチツ
プ全体の破壊を意味する欠損においては発生から
機械の停止を行なう迄の時間遅れを可能な限り少
くして停止させることが必要であるとして、前切
れ刃（刃先）欠損時の現象を分析した結果、前切
刃の欠損時には上記因子に急激な変化を生じ 切削抵抗が定常切削時の値以上である 切削分力比率が摩耗判定基準値以上である。 It was found that the same phenomenon as wear occurs depending on the shape of the workpiece, so in order to eliminate the effects of the cutting conditions and the shape of the workpiece, the cutting resistance was set at a value higher than the respective set value. Otherwise, the detection conditions are not met, and if the cutting force ratio during cutting continues to be greater than the set value (wear judgment criterion) for a certain period of time (for example, 1 to 1.2 seconds), a flank wear detection signal will be issued. In particular, we have taken into consideration the possibility of stable tool wear detection even for dry cutting and workpiece materials that produce burrs, such as workpiece material WG. Although stopping is not necessary, in the case of a large chip on the cutting edge or a chip that destroys the entire chip, it is necessary to minimize the time delay between the occurrence of the chip and the time when the machine is stopped. As a result of analyzing the phenomena when the cutting edge (cutting edge) breaks, it is found that when the front cutting edge breaks, there is a sudden change in the above factors: the cutting resistance is higher than the value during steady cutting, the cutting force ratio is higher than the wear judgment standard value. .

切削分力比率Fn／Fcの時間に対する正の微
係数が一定値以上である ことが同時に生じることを見出しこの３つの複
合信号によつて検出できることを確認した。 We found that the positive differential coefficient of the cutting force ratio Fn/Fc with respect to time is greater than a certain value at the same time, and confirmed that it can be detected using these three composite signals.

従つて本発明は上記の研究の結果にもとづきな
されたもので切刃の欠損に対し短時間に機械に指
令が出せる切削時の異常現象監視方法を提供しよ
うとするもので、本発明の要旨は切削中の工具に
かかる３分力の分力比率背分力／主分力が設定値
を越え主分力が設定値以上での背分力／主分力の
時間に対する微係数が設定値を越えたときを前切
刃の欠損とみなし必要なる信号を機械に送るよう
にしたことを特徴とするものである。 Therefore, the present invention has been made based on the results of the above-mentioned research, and aims to provide a method for monitoring abnormal phenomena during cutting that can issue commands to the machine in a short time in response to chipping of the cutting edge.The gist of the present invention is to The component force ratio of the three component forces applied to the tool during cutting When the thrust force/principal force exceeds the set value and the principal component force exceeds the set value, the differential coefficient of the thrust force/principal force with respect to time is the set value. This feature is characterized in that when the cutting edge is exceeded, it is regarded as a failure of the front cutting edge and the necessary signal is sent to the machine.

以下本発明の実施例を図面にもとづき説明する
旋盤のチヤツク１と心押台のセンタ２で支持され
た工作物３は刃物台に設けられた切削動力計４に
よつて切削中の切削抵抗の３分力送り分力Ft、
背分力Fn、主分力Fcが計測されそれを動歪計を
介して取り出す。３分力の計測値は増巾器５によ
つて必要なるレベルまで増巾され、その出力の送
り分力Ft、背分力Fn、主分力Fcはそれぞれ比較
器６，７，８に入力されそれぞれの切削初期値に
対する設定値と比較されるとともに送り分力Ft
と主分力Fcが割算器９に送られ、背分力Fnと主
分力Fcとが演割器１０に送られ切削分力比率
Ft／FcとFn／Fcがそれぞれ割算される。この割
算値Ft／Fcは比較器１１に入力されて切削初期
値に対し工作物の加工公差によつて決められる設
定値（摩耗判定基準値）と比較され割算値Fn／
Fcは比較器１２に入力され切削初期値に対する
工作物の加工公差で決められる設定値（摩耗判定
基準値）と比較されるとともに切削分力比率
Fn／Fcは微分器１３に入力されて時間に対する
微係数ｄ（Fn／Fc）／dtを演算する。演算値ｄ
（Fn／Fc）／dtは比較器１４に入力されて設定値
と比較される。３分力のそれぞれの比較器６，
７，８、切削分力比率の比較器１１，１２、微係
数の比較器１４におけるそれぞれの設定値は、例
えば Ftが初期値411Nに対し設定値650N Fnが初期値283Nに対し設定値が350N Fcが初期値982Nに対し設定値が1050N Ft／Fcが初期値40.1％に対し設定値が53％ Fn／Fcが初期値28.2％に対し設定値が41.2％ 主分力Fcの設定値＋Fn／Fcの微係数ｄ（Fn／
Fc）／dtの設定値が30％／20msecというように
決められる。 Embodiments of the present invention will be explained below with reference to the drawings.A workpiece 3 supported by a chuck 1 of a lathe and a center 2 of a tailstock is controlled by a cutting dynamometer 4 installed in a tool post to measure cutting resistance during cutting. 3 component force feed component force Ft,
Back force Fn and principal force Fc are measured and taken out via a dynamic strain meter. The measured value of the three component forces is amplified to the required level by the amplifier 5, and the output of the feed component force Ft, back component force Fn, and principal component force Fc are input to comparators 6, 7, and 8, respectively. is compared with the set value for each initial cutting value, and the feed force Ft
and principal component force Fc are sent to the divider 9, and back force Fn and principal component force Fc are sent to the calculator 10 to obtain the cutting force ratio.
Ft/Fc and Fn/Fc are each divided. This division value Ft/Fc is input to the comparator 11 and compared with the set value (wear judgment reference value) determined by the machining tolerance of the workpiece against the initial cutting value, and the division value Fn/
Fc is input to the comparator 12 and compared with a set value (wear judgment reference value) determined by the machining tolerance of the workpiece with respect to the initial cutting value, and the cutting force ratio
Fn/Fc is input to a differentiator 13 to calculate a differential coefficient d(Fn/Fc)/dt with respect to time. Calculated value d
(Fn/Fc)/dt is input to the comparator 14 and compared with a set value. Comparators 6 for each of the three component forces;
7, 8. The respective set values in the cutting force ratio comparators 11 and 12 and the differential coefficient comparator 14 are, for example, Ft is the initial value 411N and the set value is 650N, Fn is the initial value 283N and the set value is 350N. Fc is initial value 982N, set value is 1050N Ft/Fc is initial value 40.1%, set value is 53% Fn/Fc is initial value 28.2%, set value is 41.2% Principal force Fc setting value + Fn/ Differential coefficient d of Fc (Fn/
The setting value of Fc)/dt is determined as 30%/20msec.

３分力の比較器６，７，８及び切削分力比率の
比較器１１，１２の出力Ａ，Ｂ，Ｃ，Ｄ，Ｅは摩
耗判定器１５に入力される。各比較器において設
定値を越えたときその出力が“Ｈ”レベルとな
る。空切削やバリを生ずる被削材に対して安定し
た検出をするための摩耗判定器１５内のタイマで
設定された一定時間１〜1.2sec間“Ｈ”レベルが
継続していると摩耗判定器１５の出力Ｇ，Ｈ，
Ｊ，Ｋは“Ｈ”レベルとなつて工作機械１７に送
られ刃物台の送りを停止しまた必要により摩耗表
示をして摩耗した工具の工具交換を指令しタレツ
ト或いは自動工具交換装置で新しい工具と交換さ
れ、再び工作機械１７の送りが続行される。なお
摩耗判定器１５の出力としては切削分力比率の出
力Ｇ，Ｈ或いは３分力と切削分力比率との組合わ
せの出力Ｊ，Ｋ等で組合わせでは主切刃に対して
はFtとFt／Fc、前切刃に対してはFnとFn／Fc
とする。一方比較器１４の出力Ｆは欠損判定器１
６に入力され微係数ｄ（Fn／Fc）／dtが設定値
を越えたとき出力Ｆが“Ｈ”レベルとなる。欠損
判定器１６は主分力Fcの比較器８の出力Ｃ切削
分力比率Fn／Fcの比較器１２の出力Ｅと前記出
力Ｆとが入力するAND回路で構成され、主分力
値Fcが設定値を越えた“Ｈ”レベルと切削分力
比率Fn／Fcが摩耗判定基準値を越えた“Ｈ”レ
ベルと微係数ｄ（Fn／Fc）／dtが設定値を越え
た“Ｈ”レベルとの３出力でAND条件を満足し
た出力Ｌの“Ｈ”レベルで工作機械１７の送り停
止または機械を全停止させる。 The outputs A, B, C, D, and E of the three-component force comparators 6, 7, and 8 and the cutting force ratio comparators 11, 12 are input to the wear determination device 15. When the set value of each comparator is exceeded, its output becomes "H" level. If the "H" level continues for a fixed period of 1 to 1.2 seconds set by the timer in the wear detector 15, which is used to stably detect workpiece materials that cause dry cutting or burrs, the wear detector 15 outputs G, H,
J and K become "H" level and are sent to the machine tool 17 to stop the feed of the tool rest, and if necessary, display a wear indication and command the tool replacement of the worn tool, and the turret or automatic tool changer replaces the tool with a new tool. , and the feeding of the machine tool 17 is continued again. The output of the wear judge 15 is the output G, H of the cutting force ratio, or the output J, K of the combination of the 3-component force and the cutting force ratio, and in combination, it is Ft for the main cutting edge. Ft/Fc, Fn and Fn/Fc for the front cutting edge
shall be. On the other hand, the output F of the comparator 14 is
When the differential coefficient d(Fn/Fc)/dt exceeds the set value, the output F becomes "H" level. The defect determination device 16 is constituted by an AND circuit into which the output E of the comparator 12 of the cutting force ratio Fn/Fc and the output F are input, and the output C of the comparator 8 of the principal force Fc is inputted, and the principal force value Fc is "H" level that exceeds the set value, "H" level that the cutting force ratio Fn/Fc exceeds the wear judgment reference value, and "H" level that the differential coefficient d(Fn/Fc)/dt exceeds the set value At the "H" level of the output L that satisfies the AND condition with the three outputs, the feed of the machine tool 17 is stopped or the machine is completely stopped.

次に上記の検出装置による実験結果を述べる。
工具欠損を簡単に発生させるために前記と同様に
被削材s45cにスポツト溶接部を設け切削速度Ｖ＝
2.5m／sec、切入みｄ＝２mm、送りｆ＝0.3mm／
rev工具P20で乾切削を行つた。そして摩耗判定
には切削分力比率のみで行なうものとする。欠損
発生前後の切削抵抗３分力Ft，Fn，Fc、切削分
力比率Ft／Fc、Fn／Fcの時間に対する微係数の
変化を示す第２図において、切削が進行すると最
初に溶接部による主切刃のチツピングが生じ送り
分力Ftが切削初期値411.6Nから、切削分力比率
Ft／Fcが切削初期値40.1％から増大する。切削
分力比率Ft／Fcが横逃げ面摩耗検出用の摩耗判
定基準値53％を越えると工具摩耗がはげしく工作
物の加工公差内に入らないとして比較器１１の出
力Ｄが“Ｈ”レベルとなる。この“Ｈ”レベルが
タイマ設定時間1see間継続されると摩耗判定器１
５の出力Ｇが“Ｈ”レベルとなり工作機械１７に
信号を送る。本来ならこの信号が刃物台送りを停
止させて必要なる工具交換を行なわせる。さらに
切削が進むと主切刃のチツピングによる摩耗が進
行し送り分力Ft、切削分力比率Ft／Fcがより増
大し前切刃にチツピングが生じ主分力Fc、背分
力Fn、切削分力比率Fn／Fcも増大しはじめる。
しかし切削分力比率Fn／Fcは前切刃が欠損する
までは検討して設定された前逃げ面摩耗検出用の
摩耗判定基準値41.2％を越えないが、切削の続行
によつてチツピングが大きくなり前切刃が欠損す
ると背分力Fnと切削分力比率Fn／Fcは急激に増
大する。このため切削分力比率Fn／Fcが前記の
前逃げ面摩耗検出用の摩耗判定基準値を越え比較
器１２の出力Ｅが“Ｈ”レベルとなりこのレベル
がタイマで設定された1see間継続されると摩耗判
定器１５の出力Ｈが“Ｈ”レベルとなり工作機械
１７に信号を送る。また前切刃の欠損した
10msec後に主分力Fcの設定値＋微係数ｄ（Fn／
Fc）／dtが63％／10msとなり設定値30％／
20mseeを越え比較器１４の出力Ｆが“Ｈ”レベ
ルとなる。一方切削分力比率Fn／Fcは100％とな
り設定値41.2％を越えて比較器１２の出力Ｅは
“Ｈ”レベルとなつており、また主分力Fcも
1226.Nとなり設定値1050Nを越え“Ｈ”レベルと
なつているため、欠損判定器１６の３入力はすべ
て“Ｈ”レベルでAND回路のAND条件を満足し
出力Ｌが“Ｈ”レベルとなり工作機械１７に信号
を送る。本来なら機械の送り停止あるいは全停止
させる。 Next, experimental results using the above detection device will be described.
In order to easily cause tool breakage, a spot weld is provided on the workpiece material s45c in the same manner as above, and the cutting speed V=
2.5m/sec, depth of cut d=2mm, feed f=0.3mm/
Dry cutting was done with rev tool P20. It is assumed that the wear judgment is performed only based on the cutting force ratio. In Figure 2, which shows the changes in the differential coefficients of the three cutting force components Ft, Fn, and Fc, and the cutting force ratios Ft/Fc and Fn/Fc with respect to time before and after chipping occurs, as cutting progresses, the main Chipping of the cutting edge occurs, and the feed force Ft changes from the initial cutting value of 411.6N to the cutting force ratio.
Ft/Fc increases from the initial cutting value of 40.1%. When the cutting force ratio Ft/Fc exceeds the wear judgment reference value of 53% for side flank wear detection, the tool wear is so severe that it is not within the machining tolerance of the workpiece, and the output D of the comparator 11 becomes "H" level. Become. When this “H” level continues for the timer setting time 1see, the wear judgment device 1
The output G of 5 becomes "H" level and sends a signal to the machine tool 17. This signal would normally stop the turret feed and allow any necessary tool changes to be made. As the cutting progresses further, wear due to chipping of the main cutting edge progresses, and the feed component force Ft and cutting force ratio Ft/Fc further increase, causing chipping to occur on the front cutting edge. The force ratio Fn/Fc also begins to increase.
However, the cutting force ratio Fn/Fc does not exceed the wear criterion value of 41.2% for detecting front flank wear until the front cutting edge is damaged, but as cutting continues, chipping increases. When the front cutting edge is damaged, the back force Fn and the cutting force ratio Fn/Fc rapidly increase. Therefore, the cutting force ratio Fn/Fc exceeds the wear criterion value for detecting front flank wear, and the output E of the comparator 12 goes to "H" level and continues at this level for 1see set by the timer. Then, the output H of the wear determiner 15 becomes "H" level and sends a signal to the machine tool 17. Also, the front cutting edge was missing.
After 10 msec, set value of principal force Fc + differential coefficient d (Fn/
Fc)/dt becomes 63%/10ms, setting value 30%/
When the time exceeds 20 msee, the output F of the comparator 14 becomes "H" level. On the other hand, the cutting force ratio Fn/Fc is 100%, exceeding the set value of 41.2%, the output E of the comparator 12 is at "H" level, and the principal force Fc is also
1226.N, which exceeds the set value of 1050N and becomes "H" level, so all three inputs of the defect determination unit 16 are "H" level, satisfying the AND condition of the AND circuit, and the output L becomes "H" level and the operation is completed. Send a signal to machine 17. Normally, this would stop the machine's feed or completely stop it.

以上詳述したように本発明は切削分力比率
Fn／Fcの急激な変化を時間に対する微係数で検
出し設定値以上の主分力と切削分力比率Fn／Fc
との複合信号によつて前切刃の欠損を知るように
なしたので、切削の続行不可能の切刃の欠損に対
して短時間内で確実に検出が可能である。またこ
のため工作物或いは刃物台等に損傷を与えるなど
の２次的な損傷をなくすることができ無人化運転
などの信頼度を向上させることができる特徴を有
する。 As described in detail above, the present invention has a cutting force ratio
Detects sudden changes in Fn/Fc using a differential coefficient with respect to time, and the principal component force and cutting force ratio Fn/Fc that exceeds the set value
Since the chipping of the front cutting edge is known from the composite signal of the cutting edge, chipping of the cutting blade that makes it impossible to continue cutting can be reliably detected within a short period of time. Further, this has the feature that secondary damage such as damage to the workpiece or the turret can be eliminated, and reliability of unmanned operation can be improved.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の実施に用いる検出装置のブロ
ツク線図、第２図は切削中工具のチツピング、欠
損による切削力の３分力、切削分力比率、切削分
力比率Fn／Fcの時間に対する微係数の変化を示
す図、第３図は実験における切削抵抗、切削分力
比率の計測ブロツク線図、第４図は切削速度と切
削分力との関係図、第５図は切削速度と切削分力
比率との関係図、第６図は送りと切削分力比率と
の関係図、第７図は切込みと切削分力比率との関
係図、第８図はノーズ半径と切削分力比率との関
係図、第９図、第１０図は被削材質と切削分力比
率との関係図、第１１図は正常工具と損傷をもつ
工具での切削実験結果を示す図、第１２図は切削
実験における工具欠損時の切削抵抗、切削分力比
率の変化を示す図、第１３図は被削材の形状を示
す図、第１４図は被削材形状による切削抵抗、切
削分力比率および微係数の変化を示す図である。 ４……切削動力計、９，１０……割算器、６，
７，８，１１，１２，１３……比較器、１５……
摩耗判定器、１６……欠損判定器。 Figure 1 is a block diagram of the detection device used to implement the present invention, Figure 2 is the 3-component force of cutting force due to chipping and chipping of the tool during cutting, the cutting force ratio, and the time of the cutting force ratio Fn/Fc. Figure 3 is a measurement block diagram of cutting force and cutting force ratio in the experiment, Figure 4 is a diagram showing the relationship between cutting speed and cutting force, and Figure 5 is a diagram showing the relationship between cutting speed and cutting force. Figure 6 is a diagram of the relationship between feed and cutting force ratio, Figure 7 is a diagram of the relationship between depth of cut and cutting force ratio, and Figure 8 is a diagram of the relationship between nose radius and cutting force ratio. Figures 9 and 10 are relationship diagrams between workpiece material and cutting force ratio, Figure 11 is a diagram showing cutting experiment results with a normal tool and a damaged tool, and Figure 12 is a diagram showing the relationship between the workpiece material and the cutting force ratio. Figure 13 shows the shape of the workpiece, and Figure 14 shows the cutting resistance, cutting force ratio and cutting force ratio depending on the shape of the workpiece. FIG. 3 is a diagram showing changes in differential coefficients. 4... Cutting dynamometer, 9, 10... Divider, 6,
7, 8, 11, 12, 13... comparator, 15...
Wear judgment device, 16...Deficiency judgment device.

Claims (1)

【特許請求の範囲】[Claims] １ 切削中に切削工具にかかる切削抵抗の３分力
の内主分力と、主分力に対する背分力の切削分力
比率並びに該分力比率の時間に対する微係数を求
め、前記分力比率が設定値を越え主分力が設定値
以上での前記分力比率の時間に対する微係数が設
定値を越えたとき工具の前切刃の欠損とみなして
機械に必要なる信号を送るようにしたことを特徴
とする切削時の異状現象監視方法。1. Find the principal component force of the three components of cutting force applied to the cutting tool during cutting, the cutting force ratio of the back force to the principal component force, and the differential coefficient of the component force ratio with respect to time, and calculate the component force ratio. exceeds the set value, and when the differential coefficient of the component force ratio with respect to time exceeds the set value when the principal force component exceeds the set value, it is assumed that the front cutting edge of the tool is broken and the necessary signal is sent to the machine. A method for monitoring abnormal phenomena during cutting, characterized by: