JP2013124889A - Contour shape measuring method and contour shape measuring device - Google Patents
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本発明は、工作機械に用いられる加工工具などの輪郭形状評価を行うためのものであり、レーザーなどの光ビームを測定プローブとして用い、加工工具先端の輪郭形状を測定評価する輪郭形状測定方法及び輪郭形状測定装置に関するものである。本発明は、工作機械の加工工具先端の評価に限らず、例えば形状測定機の触針や硬度計の圧子などの輪郭形状にも適用できる。 The present invention is intended to evaluate a contour shape of a processing tool used in a machine tool, and uses a light beam such as a laser as a measurement probe to measure and evaluate the contour shape of the tip of a processing tool and The present invention relates to a contour shape measuring apparatus. The present invention is not limited to the evaluation of the processing tool tip of a machine tool, but can be applied to contour shapes such as a stylus of a shape measuring machine and an indenter of a hardness meter.
超精密機械加工においては、バイトやエンドミルなどの工具先端輪郭形状は、工作機械のスライドなどの性能と同様に加工精度に直接影響する。そのため、加工精度を保証するためには、工具の輪郭形状を精度良く測定し、その管理を適切に実施する必要がある。 In ultra-precision machining, the tool tip contour shape such as a bite and end mill directly affects the machining accuracy as well as the performance of machine tool slides. Therefore, in order to guarantee the machining accuracy, it is necessary to accurately measure the contour shape of the tool and appropriately manage it.
従来、バイトやエンドミルなど工具の輪郭測定には、接触式形状測定機、光学式形状測定機、光学顕微鏡、電子顕微鏡などが用いられてきた（例えば、非特許文献１、２または３参照）。 Conventionally, contact-type shape measuring machines, optical shape measuring machines, optical microscopes, electron microscopes, and the like have been used for measuring the contours of tools such as tools and end mills (see, for example, Non-Patent Documents 1, 2, or 3).
従来の接触式測定機では、バイトの切れ刃など鋭利な輪郭形状を測定する場合、接触圧による輪郭形状へのダメージが生じる問題がある。光学式形状測定機では、基本的に工具輪郭形状の法線方向あるいはそれに近い方向から測定する必要があり、鋭利な刃先における散乱光の影響で、測定が困難な場合が多い。また、工具輪郭形状の側面から測定する工具顕微鏡などの光学顕微鏡では、光の回折限界によって測定分解能がミクロンオーダに制限され、高精度な工具輪郭形状に対応できない。電子顕微鏡は、真空中で測定する必要があり、加工機上測定には対応できないこと、電子ビームによる刃先輪郭形状へのダメージがあること等の問題がある。 In the conventional contact-type measuring machine, when measuring a sharp contour shape such as a cutting edge of a cutting tool, there is a problem that damage to the contour shape due to contact pressure occurs. In an optical shape measuring machine, it is basically necessary to measure from the normal direction of the tool contour shape or a direction close thereto, and measurement is often difficult due to the influence of scattered light at a sharp blade edge. Further, in an optical microscope such as a tool microscope that measures from the side of the tool contour shape, the measurement resolution is limited to the micron order due to the diffraction limit of light, and it cannot cope with a highly accurate tool contour shape. The electron microscope needs to be measured in a vacuum, and has problems such as being unable to cope with the measurement on the processing machine and being damaged by the electron beam on the edge shape.
一方、工具先端の輪郭形状は、その生産過程および使用過程において常に変化している。そのため、工作機械の加工精度を保証するため、頻繁に工具先端輪郭形状を測定する必要がある。更に、超精密機械加工においては、工作機械への工具取り付けおよび調整が容易ではないことが多く、工具を工作機械に取り付けたまま、すなわち加工機上での工具先端輪郭測定が好まれる。加工機上での工具先端輪郭測定の例としては、顕微鏡による撮像観察が挙げられる（例えば、非特許文献４参照）。 On the other hand, the contour shape of the tool tip constantly changes during its production process and use process. Therefore, in order to guarantee the processing accuracy of the machine tool, it is necessary to frequently measure the tool tip contour shape. Further, in ultra-precision machining, it is often not easy to attach and adjust the tool to the machine tool, and it is preferable to measure the tool tip contour while the tool is attached to the machine tool, that is, on the processing machine. An example of measuring the tool tip contour on the processing machine is imaging observation with a microscope (see, for example, Non-Patent Document 4).
しかしながら、加工機上における空間的制約により、顕微鏡などの測定系を加工機上に搭載するのは容易ではなく、加工工程において頻繁に工具先端輪郭形状を評価し管理するのは容易ではない。 However, due to spatial constraints on the processing machine, it is not easy to mount a measurement system such as a microscope on the processing machine, and it is not easy to frequently evaluate and manage the tool tip contour shape in the processing process.
その一方で、工作機械においては、ツールセッターと呼ばれる工具測定装置が用いられることがある。これは工作機械上での工具位置合わせおよび工具損傷検出に用いられるもので、接触式および光学式のものが利用されている。また、このツールセッターを利用した工具先端輪郭形状の評価も行われているが、エンドミルやドリル等の円筒状加工工具を回転させて直径の変化を測定し、それから円筒状加工工具の外周輪郭形状を評価するに留まっており（例えば、非特許文献５、６参照）、バイトのような直線、円弧、放物線などの輪郭形状を持つ工具には対応できない。 On the other hand, a tool measuring device called a tool setter is sometimes used in a machine tool. This is used for tool alignment and tool damage detection on a machine tool, and a contact type and an optical type are used. In addition, the tool tip contour is also used to evaluate the tool tip contour shape. By rotating a cylindrical processing tool such as an end mill or a drill, the change in diameter is measured, and then the outer contour shape of the cylindrical processing tool is measured. (For example, refer to Non-Patent Documents 5 and 6), and cannot be applied to a tool having a contour shape such as a straight line such as a bite, an arc, or a parabola.
特許文献１には、従来の工具顕微鏡と同様の光学系を用い、コリメート光を測定対象であるワークに照射し、ＣＣＤカメラでその投影像を捕捉してエッジ形状を検出する方法および装置に関する発明が開示されている。ＣＣＤカメラの画像からエッジの輪郭形状を一括して評価できる利点を持っているが、前述の光学式顕微鏡と同様、光の回折限界によって測定分解能がミクロンオーダに制限され、高精度な工具輪郭形状には対応できない。 Patent Document 1 discloses an invention relating to a method and an apparatus for detecting an edge shape by using a similar optical system as a conventional tool microscope, irradiating a work to be measured with collimated light, and capturing a projection image with a CCD camera. Is disclosed. Although it has the advantage that the edge contour shape can be collectively evaluated from the image of the CCD camera, the measurement resolution is limited to the micron order due to the diffraction limit of light, as with the optical microscope described above, and the tool contour shape is highly accurate. Can not respond.
本発明は、従来の課題に着目してなされたもので、レーザーなどの光ビームを測定プローブとして用い、光ビームで輪郭形状を走査し、フォトダイオードなどの光検出器に到達した光ビームの光量を検出しながら、その光量変化から、測定対象物の輪郭形状を精度良く測定することができる輪郭形状測定方法及び輪郭形状測定装置を提供することを目的としている。 The present invention has been made paying attention to conventional problems, and uses a light beam such as a laser as a measurement probe, scans the contour shape with the light beam, and the amount of light beam that reaches a photodetector such as a photodiode. An object of the present invention is to provide a contour shape measuring method and a contour shape measuring apparatus capable of accurately measuring the contour shape of a measurement object from the change in the amount of light.
本発明によれば、工作機械に用いられる加工工具などの輪郭形状測定方法であって、測定対象物の輪郭部を照射する微小径の光ビームと、前記輪郭部を通過する光量を検出する光検出器とを有し、前記測定対象物の既知の形状を基準輪郭形状とし、前記光ビームの中心が前記基準輪郭形状に沿って移動したときに、前記基準輪郭形状の曲率半径と前記光ビームの断面半径と前記光ビーム内の光強度分布とから、前記光検出器で検出される基準通過光量を算出する基準通過光量算出ステップと、前記光ビームが前記測定対象物の輪郭を横切るように輪郭の近傍をスキャンして、前記光検出器で得られた各々の光ビーム位置での通過光量が前記基準通過光量になる点をつないで、前記測定対象物の推定輪郭形状を算出する輪郭形状算出ステップと、前記基準輪郭形状を前記推定輪郭形状で置き換え、前記基準通過光量の修正値を算出し、前記光検出器で得られた通過光量が修正された基準通過光量になる点をつないでより真の形状に近い修正輪郭形状を算出し、それを繰り返すことによって、前記修正輪郭形状を真の輪郭形状に収束させるための輪郭形状修正ステップと、を備えることを特徴とする輪郭形状測定方法が得られる。 According to the present invention, there is provided a method for measuring a contour shape of a machining tool or the like used in a machine tool, a light beam having a small diameter that irradiates a contour portion of a measurement object, and a light that detects the amount of light passing through the contour portion. A known contour of the measurement object as a reference contour shape, and when the center of the light beam moves along the reference contour shape, the radius of curvature of the reference contour shape and the light beam A reference passing light amount calculating step for calculating a reference passing light amount detected by the photodetector from a cross-sectional radius of the light beam and a light intensity distribution in the light beam, and so that the light beam crosses the contour of the measurement object. Contour shape that scans the vicinity of the contour and calculates the estimated contour shape of the measurement object by connecting the points where the passing light amount at each light beam position obtained by the photodetector becomes the reference passing light amount Calculation step and Replacing the reference contour shape with the estimated contour shape, calculating a correction value of the reference passing light amount, and connecting the points where the passing light amount obtained by the photodetector becomes the corrected reference passing light amount is a more true shape A contour shape measuring method comprising: a contour shape correcting step for converging the corrected contour shape to a true contour shape by calculating a corrected contour shape close to and repeating the calculation.
また、本発明によれば、工作機械に用いられる加工工具などの輪郭形状測定装置であって、断面形状が円形の微小径の光ビームと、前記光ビームの一部で曲率半径が一定の測定対象物の輪郭部を照射したときに、前記測定対象物の輪郭部を通過した前記光ビームの通過光量を検出する光検出器と、前記光ビームを前記測定対象物の輪郭部に沿って走査する走査手段と、前記測定対象物の既知の形状を基準輪郭形状とし、前記光ビームの中心が前記基準輪郭形状に沿って走査したときに、前記基準輪郭形状の曲率半径と前記光ビームの断面半径と前記光ビーム内の光強度分布とから、前記光検出器で検出される基準通過光量を算出する基準通過光量算出手段と、前記光ビームが前記測定対象物の輪郭を横切るように輪郭の近傍を往復走査して、実際の走査で前記光検出器により得られた各走査位置での通過光量が前記基準通過光量になる点をつないで、前記測定対象物の推定輪郭形状を算出する輪郭形状算出手段と、前記基準輪郭形状を前記推定輪郭形状で置き換え、前記基準通過光量の修正値を算出し、前記光検出器で得られた通過光量が修正された基準通過光量になる点をつないでより真の形状に近い修正輪郭形状を算出し、それを繰り返すことによって、前記修正輪郭形状を真の輪郭形状に収束させるための輪郭形状修正手段と、を備えることを特徴とする輪郭形状測定装置が得られる。 Further, according to the present invention, there is provided a contour shape measuring apparatus such as a processing tool used in a machine tool, wherein a light beam having a minute diameter with a circular cross-sectional shape and a constant curvature radius in a part of the light beam are measured. A light detector that detects the amount of light beam that has passed through the contour portion of the measurement object when the contour portion of the measurement object is irradiated, and scans the light beam along the contour portion of the measurement object Scanning means, and a known shape of the measurement object as a reference contour shape, and when the center of the light beam scans along the reference contour shape, the radius of curvature of the reference contour shape and the cross section of the light beam A reference passing light amount calculating means for calculating a reference passing light amount detected by the photodetector from a radius and a light intensity distribution in the light beam; and a contour of the contour so that the light beam crosses the contour of the measurement object. Scan the neighborhood back and forth, A contour shape calculating means for calculating an estimated contour shape of the object to be measured by connecting a point at which the amount of light passing at each scanning position obtained by the photodetector in the scanning at the time becomes the reference passage light amount, and the reference The contour shape is replaced with the estimated contour shape, the correction value of the reference passing light amount is calculated, and the point where the passing light amount obtained by the photodetector becomes the corrected reference passing light amount is closer to the true shape. A contour shape measuring apparatus is provided, comprising: a contour shape correcting means for calculating a corrected contour shape and repeating it to converge the corrected contour shape into a true contour shape.
更に、本発明によれば、前記光ビームは、光源からの出射光をコリメート光に変換後、微小ピンホールなどの開口を用いて成形した、または、光源からの出射光をレンズで集光して得た、断面形状が円形の微小径の光ビームであることを特徴とする輪郭形状測定装置が得られる。 Further, according to the present invention, the light beam is formed using an opening such as a minute pinhole after the light emitted from the light source is converted into collimated light, or the light emitted from the light source is collected by a lens. A contour shape measuring apparatus is obtained, which is a light beam having a small cross-sectional shape and a circular diameter.
本発明によれば、光ビームで測定対象物の輪郭を走査することで、光検出器で検出した光ビームの光量変化から、工作機械に用いられる加工工具などの測定対象物の輪郭形状を精度良く測定することができる輪郭形状測定方法及び輪郭形状測定装置を提供することができる。 According to the present invention, by scanning the contour of the measurement object with a light beam, the contour shape of the measurement object such as a processing tool used in a machine tool can be accurately determined from the change in the light amount of the light beam detected by the photodetector. It is possible to provide a contour shape measuring method and a contour shape measuring apparatus that can measure well.
本発明にかかる第１の実施形態を、図１から図５を用いて説明する。図１は、本発明にかかる第１の実施形態で用いる光学系１１の概略図である。光源２０から出射した光ビームを、コリメート光学系２３を用いて平行光とする。この平行光を微小ピンホールなどの開口２４に通し、光ビームのスポット形状を、所望のスポット径に変換する。この光ビームの光軸位置に、測定対象（工具など）およびその輪郭Ｔの先端を配置する。測定対象およびその輪郭Ｔを保持部３０に固定し、ＸＹＺ３軸方向に自由に移動できるよう装置を構成する。レンズ２２ｂは、測定対象およびその輪郭Ｔの先端によって光ビームの一部が遮られた際に発生する回折光も含めて集光するもので、集光された光の強度を光検出器２１を用いて測定する。 A first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of an optical system 11 used in the first embodiment according to the present invention. The light beam emitted from the light source 20 is converted into parallel light using the collimating optical system 23. This parallel light is passed through an opening 24 such as a minute pinhole, and the spot shape of the light beam is converted into a desired spot diameter. A measurement object (such as a tool) and the tip of its contour T are arranged at the optical axis position of the light beam. An apparatus is configured such that the measurement target and its outline T are fixed to the holding unit 30 and can be freely moved in the XYZ triaxial directions. The lens 22b collects the light including the diffracted light generated when a part of the light beam is blocked by the measurement target and the tip of the contour T. The intensity of the collected light is detected by the photodetector 21. Use to measure.
ここからは、超精密加工機上で円弧の輪郭を有する測定対象およびその輪郭Ｔを測定する場合について説明を進めるが、本発明は円孤以外の形状を有する輪郭測定にも適用可能である。また、被加工物に対して、工具が工作機械の可動軸などによってＸ、Ｙ、Ｚ各方向に相対移動することができるとする。 From here, the explanation will be given on the case of measuring a measurement object having a circular arc outline and its outline T on an ultraprecision machine, but the present invention can also be applied to measurement of an outline having a shape other than a circular arc. Further, it is assumed that the tool can be moved relative to the workpiece in the X, Y, and Z directions by a movable axis of the machine tool.
光学系１１を、加工機上で被加工物を取り付けるスライドと同じ動きをする部品に固定する。図１に示すように、光源２０と光検出器２１との間に測定対象およびその輪郭Ｔを挿入し、ビーム範囲Ｂ内に対象Ｔの一部が入るよう配置する。ここで、輪郭形状を測定するのに重要なパラメータである光ビームのサイズおよび光強度分布は、予め調べておく。 The optical system 11 is fixed to a component that moves in the same manner as a slide for mounting a workpiece on the processing machine. As shown in FIG. 1, the measurement target and its contour T are inserted between the light source 20 and the light detector 21, and are arranged so that a part of the target T enters the beam range B. Here, the size and light intensity distribution of the light beam, which are important parameters for measuring the contour shape, are examined in advance.
図２は、図１に示した光学系１１を用いて工具の輪郭形状を測定する方法における、光ビームの軌跡と測定対象である工具先端形状との関係を表わす模式図である。光ビームの基準となる点、例えば光ビームが円形の場合にはビームスポットＢの中心点が、設計輪郭形状、あるいはそれに近い既知の形状５である基準輪郭形状に一致するように走査し、各走査位置における光ビームの光量を得る。 FIG. 2 is a schematic diagram showing the relationship between the trajectory of the light beam and the tool tip shape to be measured in the method of measuring the contour shape of the tool using the optical system 11 shown in FIG. Scanning is performed so that the reference point of the light beam, for example, when the light beam is circular, the center point of the beam spot B coincides with the reference contour shape which is the design contour shape or a known shape 5 close thereto, The amount of light beam at the scanning position is obtained.
図３は、図２に示した既知の形状５や、予め調べておいた光ビームのサイズおよび光ビーム内の光強度分布から予測される光検出器の受光量ＯＡと、基準輪郭形状に一致するように走査した実験結果の受光量ＯＦから、既知の形状と測定形状との偏差を求めるグラフである。光検出器が各位置において受け取ると予測される受光量ＯＡは、予め計算によって求めることができる。いま、ある径を有する光ビームがその半径位置ａにおいて光強度Ｉ（ａ）を有する場合、あるＸ位置における既知形状５の幾何的形状と光ビームの幾何的形状と光強度Ｉ（ａ）との関係から、受光量ＯＡを求めることができる。例えば、工具輪郭形状Ｔが円形状を有しており、また光ビームの強度分布がガウス分布である場合、レーザービーム強度Ｉ（ａ）は式（１）で与えられる。 FIG. 3 matches the reference contour shape with the known shape 5 shown in FIG. 2 and the received light amount OA of the photodetector predicted from the light beam size and the light intensity distribution in the light beam that have been examined in advance. It is a graph which calculates | requires the deviation of a known shape and a measurement shape from the received light amount OF of the experimental result scanned so. The amount of received light OA predicted to be received at each position by the photodetector can be obtained in advance by calculation. Now, when a light beam having a certain diameter has a light intensity I (a) at its radial position a, the geometric shape of the known shape 5, the geometric shape of the light beam, and the light intensity I (a) at a certain X position. From this relationship, the received light amount OA can be obtained. For example, when the tool contour shape T has a circular shape and the intensity distribution of the light beam is a Gaussian distribution, the laser beam intensity I (a) is given by Expression (1).
ここでは工具輪郭形状Ｔを円形状と仮定して説明したが、その他の形状、例えば放物線形状などである場合にも同様に幾何的関係から受光量ＯＡを算出することができる。測定対象が基準輪郭形状からのずれを持たず一致する場合、上記測定受光量はＯＡと一致する。これに対し、測定対象およびその輪郭Ｔの形状が基準輪郭形状からのずれを有している場合、各位置における実験結果の受光量ＯＦは、予め求めておいた受光量ＯＡからの偏差を有することになる。このＯＡとＯＦとの偏差ＯＤを求めることで、予め調べておいた光ビームのサイズおよび光ビーム内の光強度分布に基づき、既知の形状５の基準輪郭形状からのずれを測定することができる。 Here, the tool contour shape T is assumed to be a circular shape, but the received light amount OA can be calculated from the geometric relationship in the case of other shapes such as a parabolic shape. When the measurement object matches with no deviation from the reference contour shape, the measured light reception amount matches OA. On the other hand, when the shape of the measurement target and its contour T has a deviation from the reference contour shape, the received light amount OF of the experimental result at each position has a deviation from the previously received light amount OA. It will be. By obtaining the deviation OD between OA and OF, the deviation of the known shape 5 from the reference contour shape can be measured based on the light beam size and the light intensity distribution in the light beam that have been examined in advance. .
また、工具輪郭形状は、別の光ビーム走査方法を用いた手法によっても得ることができる。図４は、光ビームを、工具輪郭形状を横切るように往復走査するときの軌跡と、輪郭周辺で工具によって遮蔽された光ビームの光量と光ビームの全光量との割合である遮蔽率との関係を示した模式図である。 The tool contour shape can also be obtained by a technique using another light beam scanning method. FIG. 4 shows the locus when the light beam is reciprocated and scanned across the tool contour shape, and the shielding ratio which is a ratio of the light amount of the light beam shielded by the tool around the contour and the total light amount of the light beam. It is the schematic diagram which showed the relationship.
この手法では、工具輪郭近傍を図４中のＸＺ平面上で走査して、各Ｘ、Ｚ位置における光の遮蔽率データＭを測定する。図４（ａ）に示すように、測定対象のＸＺ平面上で輪郭を横切るように輪郭近傍の往復走査を行う。図４（ｂ）では、円弧部の工具半径が５０μｍ、光強度分布がガウス分布である半径５μｍのレーザースポットであると仮定し、座標（ｘ，ｚ）における遮蔽率Ｍ（ｘ，ｚ）を示した。横と縦の軸はそれぞれＸ軸とＺ軸方向の座標を示し、明暗で遮蔽率を示している。この遮蔽割合が一定になる線をつないで推定輪郭１として評価する。実際の測定では、各（ｘ，ｚ）位置における受光素子の出力から、この遮蔽率が得られる。この遮蔽率データＭをもとに、推定輪郭１として工具輪郭形状を割り出す。 In this method, the vicinity of the tool contour is scanned on the XZ plane in FIG. 4, and the light shielding rate data M at each X and Z position is measured. As shown in FIG. 4A, reciprocal scanning in the vicinity of the contour is performed so as to cross the contour on the XZ plane to be measured. In FIG. 4B, it is assumed that the laser spot has a radius of 5 μm with a tool radius of the arc portion of 50 μm and a light intensity distribution of Gaussian distribution, and the shielding rate M (x, z) at the coordinates (x, z) is Indicated. The horizontal and vertical axes indicate the coordinates in the X-axis and Z-axis directions, respectively, and indicate the shielding rate in light and dark. A line where the shielding ratio becomes constant is connected and evaluated as an estimated contour 1. In actual measurement, this shielding rate is obtained from the output of the light receiving element at each (x, z) position. Based on the shielding rate data M, a tool contour shape is determined as the estimated contour 1.
なお、基準輪郭形状が不確かな場合においても、遮蔽率データＭを用いることで、ある程度確からしい工具の推定輪郭形状を求めることが可能である。この場合には、各Ｘ位置における基準遮蔽率を予め算出することが出来ないため、遮蔽率データＭにおいて、ある一定の基準遮蔽率となる点をつないで得られた曲線を推定輪郭１とみなす。この手法による輪郭形状の推定はある程度の誤差を伴うことになるが、基準輪郭形状が不確かな場合においても、ある程度確からしい工具輪郭形状を推定することが可能となる。 Even when the reference contour shape is uncertain, it is possible to obtain an estimated contour shape of the tool that is certain to some extent by using the shielding rate data M. In this case, since the reference shielding rate at each X position cannot be calculated in advance, in the shielding rate data M, a curve obtained by connecting points having a certain reference shielding rate is regarded as the estimated contour 1. . Although the estimation of the contour shape by this method involves a certain amount of error, even when the reference contour shape is uncertain, it is possible to estimate a tool contour shape that is certain to some extent.
この場合、遮蔽率データＭを用いることで、より確からしい推定輪郭形状を得ることができる。図５は、実際の光ビーム走査によって得られる遮蔽率データＭと推定輪郭１との関係を模式的に表示した図である。図５（ａ）は、得られた遮蔽率Ｍ（ｘ，ｚ）のデータ上で、例えば、Ｍ＝５０％となる各座標位置を求め、これをつないだ曲線を推定輪郭１とする。このとき、推定輪郭１と光ビームＢのサイズと光ビーム内の光強度分布とから、予測される各走査位置における予測遮蔽率Ｏ１（ｘ）が得られる。この予測遮蔽率Ｏ１（ｘ）は、光ビーム内の光強度分布を考慮して予測しているため、各ｘ位置において可変である。この遮蔽率Ｏ１（ｘ）を満足する座標（ｘ，ｚ）をつなぎ合わせることで、推定輪郭２を得ることができる。推定輪郭２は、推定輪郭１よりもより確からしい工具推定輪郭である。 In this case, a more probable estimated contour shape can be obtained by using the shielding rate data M. FIG. 5 is a diagram schematically showing the relationship between the shielding rate data M obtained by actual light beam scanning and the estimated contour 1. In FIG. 5A, for example, each coordinate position where M = 50% is obtained on the data of the obtained shielding rate M (x, z), and a curve connecting the coordinate positions is defined as the estimated contour 1. At this time, the predicted shielding rate O 1 (x) at each predicted scanning position is obtained from the estimated contour 1, the size of the light beam B, and the light intensity distribution in the light beam. Since the predicted shielding rate O 1 (x) is predicted in consideration of the light intensity distribution in the light beam, it is variable at each x position. The estimated contour 2 can be obtained by connecting coordinates (x, z) that satisfy the shielding rate O 1 (x). The estimated contour 2 is a tool estimated contour that is more likely than the estimated contour 1.
図５（ｂ）、（ｃ）はそれぞれ、実際の走査で得られた各走査位置での遮蔽率Ｍ（ｘ，ｚ）を３次元的、２次コンター図に示したものである。遮蔽率が一定となる線である推定輪郭１、各走査位置において得られた予測遮蔽率Ｏ１（ｘ）も示してある。 FIGS. 5B and 5C show the shielding rate M (x, z) at each scanning position obtained by actual scanning in a three-dimensional and secondary contour diagram. An estimated contour 1 that is a line with a constant shielding rate, and a predicted shielding rate O 1 (x) obtained at each scanning position are also shown.
実際の走査で得られた各走査位置での遮蔽率から、推定輪郭１よりも実際の輪郭形状に近い推定輪郭２を計算で決めることで、遮蔽率の分布に基づいて、再度の測定は行わず精度の高い輪郭形状評価が得られる。更に、この推定輪郭２を元に、同様の操作から推定輪郭３を求める。このような操作を繰り返し、輪郭が要求される評価精度の内に収束するならばそれを輪郭形状とすることで、より確からしい工具推定輪郭形状を得ることが可能となる。 Based on the shielding rate at each scanning position obtained by actual scanning, the estimated contour 2 closer to the actual contour shape than the estimated contour 1 is determined by calculation, so that the measurement is performed again based on the shielding rate distribution. A highly accurate contour shape evaluation can be obtained. Furthermore, based on the estimated contour 2, the estimated contour 3 is obtained from the same operation. If such an operation is repeated and the contour converges within the required evaluation accuracy, it is possible to obtain a more probable tool estimated contour shape by making it a contour shape.
次々に推定輪郭を更新し、推定輪郭が収束するかどうかを判定し、もし収束するようならばそれが評価輪郭である。図６は、繰り返し計算により、推定輪郭が収束していく様子を示す図である。測定した遮蔽率データＭをもとに、遮蔽率が５０％となる曲線を求めたものが、推定輪郭１である。真の工具先端輪郭形状よりも曲率半径が小さく評価されている。遮蔽率データＭ（ｘ，ｚ）と光ビームの強度分布とをもとにシミュレーション演算を繰り返すことで得られたのが推定輪郭３である。演算前の推定輪郭１に比較して、真の工具先端輪郭形状との誤差が大幅に縮小されていることが分かる。 The estimated contour is updated one after another to determine whether the estimated contour converges, and if it converges, it is the evaluation contour. FIG. 6 is a diagram illustrating a state in which the estimated contour converges by repeated calculation. Based on the measured shielding rate data M, the estimated contour 1 is obtained by obtaining a curve with a shielding rate of 50%. The radius of curvature is evaluated smaller than the true tool tip contour. The estimated contour 3 is obtained by repeating the simulation calculation based on the shielding rate data M (x, z) and the intensity distribution of the light beam. It can be seen that the error from the true tool tip contour is greatly reduced as compared to the estimated contour 1 before the calculation.
なお、測定に用いるレーザースポットの形状は円形であるものと仮定して説明してきたが、開口２４の形状によって円形以外のレーザースポット形状としても構わない。また、開口２４を用いる場合には、光源としてレーザーを用いるのが好ましいが、開口２４の形状および寸法によっては、例えば白色光源、ＬＥＤ光源などを用いても差し支えない。更に、上記説明では、測定対象である工具側の位置制御によるレーザースポット走査を用いたが、測定系の構成によっては、例えば光学系全体を移動してレーザースポット走査を実現しても良く、また開口２４のみを移動してレーザースポット走査を実現しても構わない。 Although the description has been made assuming that the shape of the laser spot used for the measurement is a circular shape, the shape of the opening 24 may be a laser spot shape other than a circular shape. When the opening 24 is used, it is preferable to use a laser as the light source. However, depending on the shape and size of the opening 24, for example, a white light source, an LED light source, or the like may be used. Further, in the above description, laser spot scanning by position control on the tool side to be measured is used. However, depending on the configuration of the measurement system, for example, the entire optical system may be moved to realize laser spot scanning. Laser spot scanning may be realized by moving only the opening 24.
本発明にかかる第２の実施形態を、図７を用いて説明する。図７は、本発明にかかる第２の実施形態で用いる光学系１２の概略図である。光源２０から出射したレーザービームを、コリメート光学系２３を用いて平行光とする。この平行光をレンズ２２ａに通し、レンズ２２ａの焦点距離の位置に、測定対象およびその輪郭Ｔの先端を配置する。測定対象Ｔを保持部３０に固定し、ＸＹＺ３軸方向に自由に移動できるよう装置を構成する。測定対象およびその輪郭Ｔの先端によって一部が遮られたレーザービームは、レンズ２２ａの焦点面を同じく焦点面とするレンズ２２ｂを用いて集光する。レーザー光の一部が測定対象Ｔによって遮られた際に発生する回折光が受光部に入射しない場合、光検出器２１で受け取る光量が低下し、測定分解能の低下につながる。そこで回折光も光検出器２１で受光するためレンズ２２ｂで集光し、光検出器２１を用いて測定する。光学系の構成が違うのみで、工具先端輪郭形状の測定方法は第１の実施形態と同様である。 A second embodiment according to the present invention will be described with reference to FIG. FIG. 7 is a schematic view of the optical system 12 used in the second embodiment according to the present invention. The laser beam emitted from the light source 20 is converted into parallel light using the collimating optical system 23. The parallel light is passed through the lens 22a, and the measurement target and the tip of the contour T are arranged at the position of the focal length of the lens 22a. The apparatus is configured such that the measurement target T is fixed to the holding unit 30 and can be freely moved in the XYZ triaxial directions. The laser beam partially blocked by the measurement target and the tip of the contour T is condensed using a lens 22b having the focal plane of the lens 22a as the focal plane. When the diffracted light generated when part of the laser light is blocked by the measurement target T does not enter the light receiving unit, the amount of light received by the photodetector 21 decreases, leading to a decrease in measurement resolution. Therefore, since the diffracted light is also received by the photodetector 21, it is condensed by the lens 22 b and measured using the photodetector 21. The method for measuring the tool tip contour shape is the same as in the first embodiment, except for the configuration of the optical system.
第２の実施形態についても、レーザー光源以外に、例えば白色光源、ＬＥＤ光源などを用いても差し支えない。また、測定系の構成によっては、例えば光学系全体を移動してレーザースポット走査を実現しても構わない。 In the second embodiment, for example, a white light source or an LED light source may be used in addition to the laser light source. Further, depending on the configuration of the measurement system, for example, the entire optical system may be moved to realize laser spot scanning.
本発明を用いると、加工機上において工具先端輪郭形状を頻繁に測定し、その加工精度を保証することが可能となる。レーザースポット径は光源波長によって最小径が制限されるものの、レーザースポットの強度分布を用いることで、レーザースポットサイズの制限を大幅に低減した工具先端輪郭形状評価を行うことができる。更に本発明では、単に輪郭を追従するのではなく、１回の走査測定で輪郭近傍の遮蔽率データを取得し、これをもとに繰り返し計算することで、工具先端輪郭形状の設計値が予め分からない状態においても、真の工具先端輪郭形状に近いデータを得ることができる。繰り返し計算はプログラムを用いて計算機上で実施できるため、レーザービームの再走査による再測定は必要ない。 If this invention is used, it will become possible to measure the tool tip outline shape frequently on a processing machine, and to guarantee the processing accuracy. Although the minimum diameter of the laser spot is limited by the light source wavelength, it is possible to evaluate the tool tip contour shape by greatly reducing the limit of the laser spot size by using the intensity distribution of the laser spot. Furthermore, in the present invention, instead of simply following the contour, the shielding rate data in the vicinity of the contour is acquired by one scanning measurement, and the design value of the tool tip contour shape is calculated in advance by repeatedly calculating based on this data. Even in an unknown state, data close to the true tool tip contour can be obtained. Since iterative calculation can be performed on a computer using a program, remeasurement by rescanning the laser beam is not necessary.
１，２，３ 推定輪郭
５ 既知の形状
１１，１２ 光学系
２０ 光源
２１ 光検出器
２２ａ，２２ｂ レンズ
２３ コリメート光学系
２４ 開口
３０ 保持部
Ｔ 測定対象およびその輪郭
Ｂ ビーム範囲
ＯＡ （既知形状から予測される光検出器の）受光量
ＯＦ （基準輪郭形状に一致するような走査を行い、得られる実験結果の）受光量
ＯＤ ＯＡとＯＦとの偏差
1, 2, 3 Estimated contour 5 Known shape 11, 12 Optical system 20 Light source 21 Photo detector 22a, 22b Lens 23 Collimating optical system 24 Aperture 30 Holding part T Measurement object and its contour B Beam range OA (predicted from known shape) Received light amount OF (detected by the detector) (received light amount OD OA and OF)
Claims (3)
測定対象物の輪郭部を照射する微小径の光ビームと、前記輪郭部を通過する光量を検出する光検出器とを有し、
前記測定対象物の既知の形状を基準輪郭形状とし、前記光ビームの中心が前記基準輪郭形状に沿って移動したときに、前記基準輪郭形状の曲率半径と前記光ビームの断面半径と前記光ビーム内の光強度分布とから、前記光検出器で検出される基準通過光量を算出する基準通過光量算出ステップと、
前記光ビームが前記測定対象物の輪郭を横切るように輪郭の近傍をスキャンして、前記光検出器で得られた各々の光ビーム位置での通過光量が前記基準通過光量になる点をつないで、前記測定対象物の推定輪郭形状を算出する輪郭形状算出ステップと、
前記基準輪郭形状を前記推定輪郭形状で置き換え、前記基準通過光量の修正値を算出し、前記光検出器で得られた通過光量が修正された基準通過光量になる点をつないでより真の形状に近い修正輪郭形状を算出し、それを繰り返すことによって、前記修正輪郭形状を真の輪郭形状に収束させるための輪郭形状修正ステップと、
を備えることを特徴とする輪郭形状測定方法。 A contour shape measuring method for a processing tool used in a machine tool,
A small-diameter light beam that irradiates the contour of the measurement object, and a photodetector that detects the amount of light passing through the contour,
When the known shape of the measurement object is a reference contour shape, and the center of the light beam moves along the reference contour shape, the radius of curvature of the reference contour shape, the cross-sectional radius of the light beam, and the light beam A reference passing light amount calculating step for calculating a reference passing light amount detected by the photodetector from the light intensity distribution in
Scan the vicinity of the contour so that the light beam crosses the contour of the measurement object, and connect the points where the light amount passing through each light beam position obtained by the photodetector becomes the reference light amount. A contour shape calculating step for calculating an estimated contour shape of the measurement object;
Replacing the reference contour shape with the estimated contour shape, calculating a correction value of the reference passing light amount, and connecting the points where the passing light amount obtained by the photodetector becomes the corrected reference passing light amount is a more true shape A contour correction step for converging the corrected contour shape to a true contour shape by calculating a corrected contour shape close to
A contour shape measuring method comprising:
断面形状が円形の微小径の光ビームと、
前記光ビームの一部で曲率半径が一定の測定対象物の輪郭部を照射したときに、前記測定対象物の輪郭部を通過した前記光ビームの通過光量を検出する光検出器と、
前記光ビームを前記測定対象物の輪郭部に沿って走査する走査手段と、
前記測定対象物の既知の形状を基準輪郭形状とし、前記光ビームの中心が前記基準輪郭形状に沿って走査したときに、前記基準輪郭形状の曲率半径と前記光ビームの断面半径と前記光ビーム内の光強度分布とから、前記光検出器で検出される基準通過光量を算出する基準通過光量算出手段と、
前記光ビームが前記測定対象物の輪郭を横切るように輪郭の近傍を往復走査して、実際の走査で前記光検出器により得られた各走査位置での通過光量が前記基準通過光量になる点をつないで、前記測定対象物の推定輪郭形状を算出する輪郭形状算出手段と、
前記基準輪郭形状を前記推定輪郭形状で置き換え、前記基準通過光量の修正値を算出し、前記光検出器で得られた通過光量が修正された基準通過光量になる点をつないでより真の形状に近い修正輪郭形状を算出し、それを繰り返すことによって、前記修正輪郭形状を真の輪郭形状に収束させるための輪郭形状修正手段と、
を備えることを特徴とする輪郭形状測定装置。 A contour shape measuring device such as a processing tool used in a machine tool,
A small diameter light beam with a circular cross-sectional shape;
A light detector for detecting the amount of light passing through the contour of the measurement object when the contour of the measurement object having a constant radius of curvature is irradiated with a part of the light beam;
Scanning means for scanning the light beam along the contour of the measurement object;
When the known shape of the measurement object is a reference contour shape, and the center of the light beam is scanned along the reference contour shape, the radius of curvature of the reference contour shape, the cross-sectional radius of the light beam, and the light beam A reference passage light amount calculating means for calculating a reference passage light amount detected by the photodetector from the light intensity distribution in the inside,
Reciprocating scan of the vicinity of the contour so that the light beam crosses the contour of the object to be measured, and the amount of light passing at each scanning position obtained by the photodetector in actual scanning becomes the reference amount of light A contour shape calculating means for calculating an estimated contour shape of the measurement object;
Replacing the reference contour shape with the estimated contour shape, calculating a correction value of the reference passing light amount, and connecting the points where the passing light amount obtained by the photodetector becomes the corrected reference passing light amount is a more true shape A contour shape correcting means for calculating a corrected contour shape close to, and repeating it to converge the corrected contour shape to a true contour shape;
A contour shape measuring apparatus comprising:
The light beam is obtained by converting the light emitted from the light source into collimated light and then shaping it using an opening such as a minute pinhole, or condensing the light emitted from the light source with a lens and having a circular cross-sectional shape. The contour shape measuring apparatus according to claim 2, wherein the light beam has a very small diameter.
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| JP2011272901A JP2013124889A (en) | 2011-12-14 | 2011-12-14 | Contour shape measuring method and contour shape measuring device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020532438A (en) * | 2017-09-05 | 2020-11-12 | レニショウ パブリック リミテッド カンパニーＲｅｎｉｓｈａｗ Ｐｕｂｌｉｃ Ｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Non-contact tool setting device and method |
| JP2021506598A (en) * | 2017-12-15 | 2021-02-22 | ライシャウァー アーゲー | Methods and equipment for measuring creative machining tools |
| JP2021109298A (en) * | 2020-01-15 | 2021-08-02 | Dmg森精機株式会社 | Image processing device, machine tool and image processing method |
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2011
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2020532438A (en) * | 2017-09-05 | 2020-11-12 | レニショウ パブリック リミテッド カンパニーＲｅｎｉｓｈａｗ Ｐｕｂｌｉｃ Ｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Non-contact tool setting device and method |
| EP3679318B1 (en) | 2017-09-05 | 2022-07-20 | Renishaw PLC | Non-contact tool setting apparatus and method |
| JP7385554B2 (en) | 2017-09-05 | 2023-11-22 | レニショウ パブリック リミテッド カンパニー | Non-contact tool setting device and method |
| JP2021506598A (en) * | 2017-12-15 | 2021-02-22 | ライシャウァー アーゲー | Methods and equipment for measuring creative machining tools |
| JP7356977B2 (en) | 2017-12-15 | 2023-10-05 | ライシャウァー アーゲー | Method and device for measuring creative machining tools |
| JP2021109298A (en) * | 2020-01-15 | 2021-08-02 | Dmg森精機株式会社 | Image processing device, machine tool and image processing method |
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