JP2020038066A - Visual inspection system for gear tooth flank - Google Patents
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本発明は、歯車の歯面の巣、打痕、傷などの欠陥を検査するための歯車の歯面の外観検査システムに関する。 The present invention relates to a gear tooth surface appearance inspection system for inspecting defects such as nests, dents, and scratches on the gear tooth surface.
複数の面で表面が形成された被検査体として、例えば、歯車が挙げられる。金属歯車を製造する方法として、圧縮成形された粉末合金を焼結して製造する粉末冶金法が、よく用いられる。粉末冶金法による歯車の製造工程において、焼結する前の歯車の状態は、圧粉体なので表面に欠けが生じやすく、欠けが生じた圧粉体をそのまま焼結してしまうと表面に欠けが残った状態になる。また、焼結する際に、歯車の柔らかい表面にごみが付着した場合には、そのゴミが焼結時に焼けてしまうと、欠けが発生してしまう場合もある。欠けは、例えば歯車の歯部における先端エッジ部に発生すると、その歯車の動力伝達不足の原因になる虞がある。 As an inspection object having a surface formed by a plurality of surfaces, for example, a gear is cited. As a method of manufacturing a metal gear, a powder metallurgy method of manufacturing by sintering a compression-molded powder alloy is often used. In the manufacturing process of gears by powder metallurgy, the state of the gear before sintering is a green compact, so the surface is likely to be chipped, and if the chipped compact is sintered as it is, the surface will be chipped. It will remain. In addition, when dust is attached to the soft surface of the gear during sintering, chipping may occur if the dust burns during sintering. If chipping occurs, for example, at the leading edge portion of a tooth portion of a gear, there is a possibility that power transmission of the gear may be insufficient.
従来、歯車の表面、特に歯部の先端部を検査する場合は、作業者が目視によって欠陥があるか否かの判別を行っていた。しかし、人的に外観検査を行う場合、長時間検査を行ったときには、緊張による疲労感から見逃しや誤判定を起こしやすいし、官能的な感覚に頼るため、個人差による判定バラツキが大きく、安定した検出能力を全数にわたって保証できない。 2. Description of the Related Art Conventionally, when inspecting the surface of a gear, particularly the tip of a tooth portion, an operator visually determines whether or not there is a defect. However, when performing a visual inspection manually, over a long period of inspection, fatigue tends to overlook or misjudgment due to strain. Can not be guaranteed for all of them.
特許文献１に開示されている外観検査装置は、被検査体の被検査面に平行光を一定方向から照射し、被検査体に当たって反射した光を撮像手段で受光して画像処理を行い、モニタ画像上に明暗パターンとして映し出し、その明暗パターンを正常時のパターンと比較して被検査面の異常を検出するようになっている。 The appearance inspection apparatus disclosed in Patent Document 1 irradiates parallel light to a surface to be inspected of an object to be inspected from a certain direction, receives light reflected by the object to be inspected by an imaging unit, performs image processing, and performs monitor processing. The light-dark pattern is projected on an image, and the light-dark pattern is compared with a normal pattern to detect an abnormality on the surface to be inspected.
しかし、上記の特許文献１の検査方法は多数のカメラを使用するが、被検査体を回転させながらどのタイミングで撮像を行うのか特に言及がないため、歯側面（歯面）上にある欠陥などを見逃す可能性がある。 However, although the inspection method of Patent Document 1 uses a large number of cameras, since there is no particular reference to when to take an image while rotating the object to be inspected, a defect on the tooth side surface (tooth surface), etc. Could miss.
本発明は、上記した問題に着目してなされたもので、歯車の歯面の歯底、歯側面、歯先を含んだ全面を細かくカバーできる歯車の歯面の外観検査システムを提供することを目的とする。更に、使用するカメラは１台で経済性を顧慮する。 SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and provides a system for inspecting the appearance of a tooth surface of a gear that can cover the entire surface including the tooth bottom, the tooth side surface, and the tooth tip of the gear. Aim. In addition, a single camera is used for economical considerations.
前記課題を解決するために検討した結果、本発明に係る外観検査システムは、歯車の歯面の外観検査システムであって、撮像装置及びＬＥＤ照明を用い、被検査体の歯車を回転させながら１／ｎピッチ毎（但し、ｎは２以上の正の整数）に歯面の撮像を行う撮像手段と、撮像した画像を、画像処理を用いて欠陥を検出する画像処理手段を有する。
また、本発明に係る外観検査システムは、前記被検査体を回転させながら１／２ピッチ毎（ｎ＝２）に撮像を行う撮像手段を有すると好ましい。
As a result of studying to solve the above problem, the appearance inspection system according to the present invention is a gear tooth surface appearance inspection system, which uses an image pickup device and LED illumination while rotating the gear of the object to be inspected. It has an imaging unit for imaging the tooth surface at every / n pitch (where n is a positive integer of 2 or more), and an image processing unit for detecting a defect in the captured image by using image processing.
Further, it is preferable that the appearance inspection system according to the present invention includes an imaging unit that performs imaging at every ピ ッ チ pitch (n = 2) while rotating the inspection object.
また、本発明に係る外観検査システムは、ＬＥＤ照明を用い、被検査体に垂直に照射することが好ましい。 Moreover, it is preferable that the visual inspection system according to the present invention irradiate the inspection object vertically using LED illumination.
更に、本発明に係る外観検査システムは、前記ＬＥＤ照明が検査台に対して垂直方向で被検査対象物から８〜１０ｃｍ離れた位置に配置されることが好ましい。 Furthermore, in the visual inspection system according to the present invention, it is preferable that the LED illumination is arranged at a position 8 to 10 cm away from the inspection object in a direction perpendicular to the inspection table.
本発明に係る歯車の歯面の外観検査システムによれば、従来の外観検査装置では困難であった、歯車の歯面の歯底、歯側面、歯先の欠陥検出が可能になる。欠陥を検出できず、「見逃し」のケースを激減させる効果が期待できる。 ADVANTAGE OF THE INVENTION According to the external appearance inspection system of the tooth surface of the gear which concerns on this invention, the defect of the root of a tooth surface of a gear, the tooth side surface, and the tooth tip which was difficult with the conventional external appearance inspection apparatus becomes possible. The defect can not be detected, and the effect of drastically reducing the case of “missing” can be expected.
以下、本発明を実施するための形態について図面を参照しながら説明する。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
図１は実施の形態の歯車の歯面の外観検査システムの概略の全体構成図である。この外観検査システムである外観検査装置は、被検査体として歯車の歯面（ギヤの側面）の欠陥を検査する装置であり、歯車の歯面の外観検査を実行する。
ここで、歯車の歯面とは、図２に示した歯車の歯底、歯側面、歯先を含む面の総称である。また、本発明の歯車は平歯車がメインであるが、平行軸の歯車であるラック、内歯車、はすば歯車、はすばラック、やまば歯車にも適用でき、交差軸の歯車であるすぐばかさ歯車、まがりばかさ歯車、ゼロールかさ歯車、食い違い軸の歯車である円筒ウォームギア、ねじ歯車、その他のフェースギヤ、鼓形ウォームギア、ハイポイドギアの各歯車にも適用できる。
FIG. 1 is a schematic overall configuration diagram of a gear tooth surface appearance inspection system according to an embodiment. An appearance inspection apparatus, which is an appearance inspection system, is an apparatus for inspecting a defect of a tooth surface of a gear (a side surface of a gear) as an object to be inspected, and executes an appearance inspection of a tooth surface of the gear.
Here, the tooth surface of the gear is a general term for a surface including a tooth bottom, a tooth side surface, and a tooth tip of the gear shown in FIG. The gear of the present invention is mainly a spur gear, but can also be applied to racks, internal gears, helical gears, helical racks, and helical gears that are parallel shaft gears, and is a cross shaft gear. The present invention can also be applied to gears such as a straight bevel gear, a spiral bevel gear, a zelol bevel gear, a cylindrical worm gear having a staggered shaft, a screw gear, other face gears, a drum-shaped worm gear, and a hypoid gear.
図１に示すように本発明の歯車の歯面の外観検査システムは、被検査体である歯車の歯面に光を照射し画像を撮像する光学系と、光学系から送られた画像を処理し、欠陥を検出し歯車の良否の判定結果を出力する画像処理装置を備えている。 As shown in FIG. 1, a gear tooth surface appearance inspection system according to the present invention includes an optical system that irradiates light to a tooth surface of a gear, which is an object to be inspected, to capture an image, and processes an image sent from the optical system. And an image processing device for detecting a defect and outputting a determination result of the quality of the gear.
ここで、光学系にはＬＥＤ照明及びカメラの撮像装置を備え、被検査物近傍の背景に、ＬＥＤ照明から正反射光及び乱反射光照射し撮像装置によって画像を撮像する。 Here, the optical system includes an LED illumination and an imaging device of a camera, and irradiates specularly reflected light and irregularly reflected light from the LED illumination to a background near the inspection object, and captures an image with the imaging device.
前記カメラの撮像装置としては、エリアセンサ方式カメラ、ラインセンサ方式カメラ等が挙げられ、パターンサーチを行う点からエリアセンサ方式モノクロカメラであることが好ましく、例えば、５ｃｍ×５ｃｍの視野範囲の検査を行う場合２００万画素程度の解像度であることが好ましい。 Examples of the imaging device of the camera include an area sensor type camera, a line sensor type camera, and the like, and are preferably an area sensor type monochrome camera from the viewpoint of performing a pattern search. For example, inspection of a visual field range of 5 cm × 5 cm is performed. In this case, the resolution is preferably about 2 million pixels.
青色、赤色などの照明でも欠陥検出はできるが、前記ＬＥＤ照明はコントラストを明確にする観点から白色ＬＥＤ照明を用いることが好ましい。又、これらの照明光は平行光であることが好ましい。 Defects can be detected by illumination of blue, red, or the like, but it is preferable to use white LED illumination as the LED illumination from the viewpoint of clarifying the contrast. It is preferable that these illumination lights are parallel lights.
前記ＬＥＤ照明は、外径が１００〜１５０ｍｍであることが好ましく、それ以上になると被検査体の端付近の画像が不明瞭となることがある。前記のＬＥＤ照明は、円環状に配置された複数のＬＥＤを有し、カメラの撮像装置は、その円環と同じ面か、円環内の被検査体の反対側空間に配置される構成が好ましい。 The LED illumination preferably has an outer diameter of 100 to 150 mm, and if it has more than that, an image near the edge of the inspection object may be unclear. The LED illumination has a plurality of LEDs arranged in a ring, and the imaging device of the camera is arranged on the same surface as the ring or in a space on the opposite side of the object to be inspected in the ring. preferable.
前記ＬＥＤ照明が検査台に対して垂直方向で被検査体から８〜１０ｃｍ離れた位置に配置されることが好ましい。このように設置することにより、より背景と被検査物のコントラストが明確となる。 It is preferable that the LED lighting is arranged at a position 8 to 10 cm away from the object to be inspected in a direction perpendicular to the inspection table. With this arrangement, the contrast between the background and the inspection object becomes clearer.
図２は従来の歯車１ピッチ毎に撮像する状態を示す断面模式図であり、図３は本発明の歯車半ピッチ毎に撮像する状態を示す断面模式図である。
例えば、欠陥が歯側面上にあるとしたら、図２の場合、歯先を中心に撮像を行うため、欠陥が完全に映らないこともある。図３のように半ピッチ毎に撮像を行うと、歯車（ギヤ）側面の全面を細かく検査することができる。欠陥検出の検出精度を高めるには、１／ｎピッチ毎（但し、ｎは２以上の正の整数）に歯面の撮像を行い、ｎを３以上とすることで達成される。しかし、一般的には、１／２ピッチ毎で欠陥検出を行うことができる。
FIG. 2 is a schematic cross-sectional view showing a state in which an image is taken at each pitch of a conventional gear, and FIG. 3 is a schematic sectional view showing a state in which an image is taken at every half pitch of a gear according to the present invention.
For example, if the defect is on the side of the tooth, in the case of FIG. 2, since the imaging is performed centering on the tooth tip, the defect may not be completely reflected. By taking an image at every half pitch as shown in FIG. 3, the entire side surface of the gear can be inspected in detail. To improve the detection accuracy of the defect detection, the tooth surface is imaged at every 1 / n pitch (where n is a positive integer of 2 or more), and n is set to 3 or more. However, in general, defect detection can be performed at every 1/2 pitch.
例えば、被検査体の歯数が１６個の場合、半ピッチ毎に撮像を行うので歯車１回転あたり３２回の撮像が行われる。検査のタクトタイム上シャッタースピード０．５ｍｓｅｃ、撮像タイミング３５ｍｓｅｃ間隔が好ましく、撮像時間は３５ｍｓｅｃ×３２回＝１．１２ｓｅｃ／周になる。 For example, when the number of teeth of the object to be inspected is 16, imaging is performed every half pitch, so that imaging is performed 32 times per rotation of the gear. A shutter speed of 0.5 msec and an imaging timing of 35 msec are preferable in terms of the inspection tact time, and the imaging time is 35 msec × 32 times = 1.12 sec / lap.
図４は外観検査アルゴリズムのフローチャートである。まず、ステップＳ１では、撮像して被検査物の画像を得る。
ステップＳ２とＳ３では位置補正を行う。特定のパターンを認識させて、被検査体の位置が多少ずれても、毎回同じ検査領域を撮るようにする。
FIG. 4 is a flowchart of the appearance inspection algorithm. First, in step S1, an image is taken to obtain an image of the inspection object.
In steps S2 and S3, position correction is performed. By recognizing a specific pattern, the same inspection area is taken every time even if the position of the inspection object is slightly shifted.
ステップＳ４ではリアルタイム濃淡補正を行う。背景と被検査物のコントラストがより明確になり、細かいノイズが除去される。 In step S4, real-time shading correction is performed. The contrast between the background and the inspection object becomes clearer, and fine noise is removed.
ステップＳ５では２値化処理を行う。下限の輝度値を指定して、２値化する。この処理を行うことにより、欠陥部分が顕著化される。 In step S5, a binarization process is performed. Binarization is performed by designating the lower limit luminance value. By performing this processing, the defective portion becomes noticeable.
ステップＳ６では、Ｓ５で得られた２値化画像に対して膨張処理を行う。ステップＳ５までに除去することができなかったノイズを除去する。 In step S6, expansion processing is performed on the binarized image obtained in S5. Noise that could not be removed by step S5 is removed.
ステップＳ７でＳ６の処理結果が決められた閾値の範囲内にあるかどうかを判断し、結果を出力する。
そして１／２ピッチ毎の検査の場合、Ｓ１〜Ｓ７を歯数の２倍の回数を繰り返し行い、歯車の検査を終了する。
In step S7, it is determined whether or not the processing result of S6 is within a predetermined threshold range, and the result is output.
In the case of the inspection for every 1/2 pitch, S1 to S7 are repeated twice as many times as the number of teeth, and the inspection of the gear is completed.
本発明の詳細を以下の実施例で説明する。但し、本発明はこれら実施例によって何ら限定されるものではない。 The details of the present invention are described in the following examples. However, the present invention is not limited at all by these examples.
図１に示す歯車の歯面の外観検査システムを用いて、良品と不良品サンプルの検査を行った。
比較例としては、歯数１６個で、従来の１ピッチ毎に撮像（１６回／周）を行い、実施例では同一サンプルを半ピッチ毎に撮像（３２回／周）を行い、同一検査アルゴリズムを適用して欠陥検出を実行した。
Non-defective and defective samples were inspected using the gear tooth surface appearance inspection system shown in FIG.
As a comparative example, imaging is performed at every conventional pitch with 16 teeth (16 times / round). In the embodiment, the same sample is imaged at every half pitch (32 times / round), and the same inspection algorithm is used. Was applied to perform defect detection.
被検査体は、従来の目視検査により良品及び不良品として判定されたサンプルを使用した。使用したサンプルの内訳は、歯面に欠陥がない良品３個（良品１、良品２、良品３）、歯先の巣不良（巣１）、歯側面の巣不良（巣２）、歯底の巣不良（巣３）、歯側面の打痕不良（打痕１）、歯底の打痕不良（打痕２）である。
判定は、目視検査の判定と一致し正確な合否判定ができる場合を「○」、目視検査の判定と一致せず正確な合否判定ができない場合を「×」、合否判定は正しいが、欠陥部の大きさを正しく認識できない場合を「△」として評価した。
検査結果を表１に示した。
The sample to be inspected used was a sample determined as a non-defective product or a defective product by a conventional visual inspection. The breakdown of the samples used was: 3 non-defective products with no defect on the tooth surface (non-defective product 1, non-defective product 2, non-defective product 3), defective nest at the tip of the tooth (nest 1), defective nest at the side of the tooth (nest 2), Poor dents (nest 3), poor dents on the tooth side surface (dent 1), poor dents on the tooth bottom (dent 2).
Judgment is “○” when the result is consistent with the visual inspection and accurate pass / fail judgment can be made, and “X” when the result does not match the visual inspection judgment and cannot be accurate pass / fail. The case where the size of the sample could not be recognized correctly was evaluated as “△”.
The test results are shown in Table 1.
×：目視検査の判定と一致せず正確な合否判定ができない。
△：合否判定は正しいが、欠陥部の大きさを正しく認識できない。
×: Accurate pass / fail judgment cannot be made because it does not match the judgment of the visual inspection.
Δ: The pass / fail judgment is correct, but the size of the defective portion cannot be correctly recognized.
表１において、実施例ではいずれも目視検査の判定と一致する正確な合否判定を得ることができた。一方、比較例では、歯側面にある欠陥が検査領域からはずれることで欠陥検出できない見逃しが発生した。歯底にある一部欠陥に関しては、検出はできるが、画像上欠陥が正面から鮮明に映っていないため、欠陥部の大きさまでは正しく認識できないケースも存在する。 In Table 1, in each of the examples, it was possible to obtain an accurate pass / fail judgment consistent with the judgment of the visual inspection. On the other hand, in the comparative example, a defect on the side surface of the tooth was missed because the defect could not be detected due to deviation from the inspection area. Although some defects at the bottom of the tooth can be detected, there are cases where the defects are not clearly recognized from the front because the defects are not clearly seen from the front in the image.
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| CN111750789B (en) * | 2020-06-08 | 2021-10-01 | 北京工业大学 | Tooth pitch deviation and tooth profile deviation evaluation method in small module gear vision measurement |
| CN113514006A (en) * | 2021-07-01 | 2021-10-19 | 燕山大学 | Method for quickly and accurately measuring parameters of straight spur gear based on computer vision |
| CN113514006B (en) * | 2021-07-01 | 2022-08-16 | 燕山大学 | Method for quickly and accurately measuring parameters of straight spur gear based on computer vision |
| CN117197130A (en) * | 2023-11-03 | 2023-12-08 | 山东太阳耐磨件有限公司 | Driving tooth angle defect identification method based on machine vision |
| CN117197130B (en) * | 2023-11-03 | 2024-01-26 | 山东太阳耐磨件有限公司 | Driving tooth angle defect identification method based on machine vision |
| CN117474927A (en) * | 2023-12-28 | 2024-01-30 | 山东太阳耐磨件有限公司 | Driving tooth production quality detection method based on artificial intelligence |
| CN117474927B (en) * | 2023-12-28 | 2024-03-26 | 山东太阳耐磨件有限公司 | Driving tooth production quality detection method based on artificial intelligence |
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