EP0992789A1 - Einrichtung und Verfahren zur optischen Qualitätsprüfung einer Rohraussenoberfläche - Google Patents
Einrichtung und Verfahren zur optischen Qualitätsprüfung einer Rohraussenoberfläche Download PDFInfo
- Publication number
- EP0992789A1 EP0992789A1 EP99250305A EP99250305A EP0992789A1 EP 0992789 A1 EP0992789 A1 EP 0992789A1 EP 99250305 A EP99250305 A EP 99250305A EP 99250305 A EP99250305 A EP 99250305A EP 0992789 A1 EP0992789 A1 EP 0992789A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pipe
- unit
- data processing
- camera unit
- pixel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
Definitions
- the invention relates to a device for optical quality inspection Pipe outer surface, especially with regard to longitudinal grooves and others Surface defects, such as shells and scratches, according to the generic term of the Claim 1.
- the quality of the pipe outer surface of a pipe can be caused by material defects or through foreign bodies that act on the surface of the manufacturing process, be affected. This creates so-called longitudinal grooves, pores, impressions and bowls. Furthermore, when transporting the pipe in-house Damage to the outer surface - for example in the form of blows - arise. Such defective pipes are visually inspected at the end of the Manufacturing process separated.
- the pipes are checked for the types of defects described above in the Practice by sifting the pipe outer surface. This test activity is monotonous and time consuming work. The lighting conditions at the test station determine in considerable quality of testing. Flaws can be overlooked or are difficult to perceive. In this respect, the pipes are reliably checked not guaranteed.
- the invention is therefore based on the object of a device for optical To create quality inspection of an outer pipe surface with which or with which quickly and reliably relevant fault points can be recognized.
- the invention includes the technical teaching that at least one optically on the Pipe outer surface aligned and attached to a rotating frame Camera unit rotates equidistantly around the pipe to be tested and at the same time one Pipe transport device transports the pipe lengthways, the resultant helical recording area of the camera unit as an image sequence downstream data processing device is received.
- the Data processing device recognizes defects on the outer surface of the pipe and evaluates this in terms of relevance.
- the device according to the invention has the advantage that the systematic Examination of the entire surface area of the pipe along a gap helical processing reliable detection of drawing marks, Impacts or other relevant damage is possible.
- the test time can be due to high possible transport speeds of the pipe, which the Rotational speed of the rotating frame including the camera unit can be adjusted, shorten considerably. This is a reliable and quick quality check guaranteed.
- the device is therefore particularly suitable for use in the Series production of pipes.
- the data processing device preferably comprises - in the case of a block diagram Consideration - a signal conversion unit, essentially Image sequence data is processed pixel by pixel with the associated brightness value and a subsequent evaluation unit on the input side.
- the evaluation unit provides using an error detection algorithm by evaluating the The course of brightness in a defined image field determines relevant defects, whereby a downstream output unit generates at least two output values from an output value for a positive test result and another output value indicates negative test result.
- the outer tube surface is advantageously fixed to the camera unit by means of a stationary one arranged light source illuminated.
- the light source can be compared to the Camera unit can be arranged according to two principles. Firstly, the light source send the light onto the outer surface of the pipe at such angular relationships, that the light beam reflected from the outer surface of the tube is not on the Camera axis lies.
- the orthogonal to a tangent to the pipe outer surface running axis of the camera unit lies between the incident and the reflected light beam. With such geometric relationships, the Image of a defect that is visible through scattered light in the optical dark field instead of. The fault location stands out brightly from the environment.
- the light source can also be arranged so that the The outer surface of the pipe reflected the light beam exactly on the axis of the camera unit lies.
- the fault location stands out darkly from the surroundings.
- the image takes place in the so-called optical bright field.
- the camera unit is preferably designed as a line camera, the Recording line runs parallel to the longitudinal axis of the pipe to be tested.
- the light source is designed in the manner of a light stick, the The longitudinal extent also runs parallel to the longitudinal axis of the pipe to be tested.
- the use of a line scan camera guarantees because of the always equidistant Distance between the camera and the recording line on the Pipe outer surface, which corresponds to a constant radius of rotation, always sharp Illustration.
- the signal conversion unit downstream of the camera unit sets a two-dimensional image line data from the camera unit Image sequence together, on which the error evaluation is based.
- a slip ring device For signal transmission between the fixed components of the device and a slip ring device can be used for the rotating rotating frame come.
- the rotating components of the invention are safety-related Meet requirements and to protect the sensitive optical components To protect dirt, the rotating frame is advantageously in one shatterproof housing.
- At least the signal conversion unit, the evaluation unit is the Storage unit and the output unit in at least one software-controlled Integrated calculator.
- a separate computer is provided for each camera unit, with a third Computer with screen to assign parameters depending on the type of pipe to be tested can be selected from the storage unit.
- the generated by the output unit of the data processing device Output values could be a control unit of an extensive pipe testing system Serve input value.
- a programmable logic controller can be used as the control unit Control (PLC) are used.
- PLC control unit Control
- the device described above is preferably by a method operated, after which the image signals of the camera unit or the camera units in helical recording area are assembled as an image sequence, then the brightness values of the image sequence are read in pixel by pixel, then to Determination of the contrast of a pixel a comparison with the average Brightness value of an image field surrounding the pixel is then carried out Expansion of a pixel-like contiguous contrast as Contrast is determined, then a comparison of contrast and Expansion of the contrast phenomenon with a predefined contrast limit and characterizing at least one shape and size of the contrast phenomenon Expansion limit is carried out, if the predefined is exceeded Contrast limit and the expansion limit an error message is output, or if the predefined is not reached Contrast limit and the expansion limit no error message is issued.
- the pipe 1 to be tested is not along its axis by means of a further shown pipe transport device transported.
- a camera unit 3 is attached on the rotating frame 2 .
- the camera unit 3 is a CCD line scan camera trained and also attached to the rotating frame Deflecting mirror 4 orthogonal to a tangent to the pipe outer surface 5 directed.
- a light source 6 is used to illuminate the line-shaped Recording sector 7.
- Opposite the camera unit 3 of the deflecting mirror 4 and the light source 6 is a second analog constructed and in addition to that described above Assembling camera unit 3a with deflecting mirror 4a and Light source 6a provided.
- the signals generated on the output side by the camera units 3 and 3a are transmitted via a slip ring unit 9 is fed to a data processing device 10.
- the Slip ring unit 9 does not only transmit the signals from and to the camera units 3 and 3a, but also serves their power supply and the power supply of the Light sources 6 and 6a.
- the data processing device 10 is designed as a software-controlled computer and consists of a block diagram view Signal conversion unit 11, which the line signals of the camera units 3rd and 3a transformed into a two-dimensional image sequence and pixel by pixel with the associated brightness value prepared.
- a downstream evaluation unit 12 records using an algorithm described in more detail below Basis of available in a storage unit 14 and Setting parameters for a selected pipe type an evaluation of the Brightness curve in the recording area 8 and thus represents relevant defects firmly.
- a subsequent output unit 13 generates two output values, one of which Output value to a faulty and a second output value to a faultless one Pipe 1 indicates.
- This information is sent to a control unit 15 in the form of a programmable logic controller (PLC) forwarded according to the Test result on the control of the pipe transport device for the purpose of Transfer of tested pipes to various pipe stores for error-free or faulty Pipes influences.
- PLC programmable logic controller
- FIG. 2 shows the arrangement of the camera unit 3 and the rod-shaped light source 6 - here in an embodiment without optical deflection by means of a mirror - relative to Pipe outer surface 5.
- the light source 6 is on the linear recording sector 7 the pipe outer surface 5 aligned such that the light beam - marked through a dashed line - not with the optical axis of the camera unit 3 coincides.
- the outer tube surface 5 is thus recorded optically Dark field. With this principle, flaws on the outer surface of the pipe are raised 5 particularly well as a difference in brightness from the surroundings.
- the principle of fault location detection in the optical dark field falls according to the figure 3 the light beam emitted by the light source 6 under one together with the Tangent 16 formed acute angle ⁇ on the pipe outer surface 5 and will reflected at the same angle of reflection ⁇ '. This is orthogonal to tangent 16 optical axis 17 of the camera unit 3 arranged. Lift due to stray light defects on the otherwise smooth and reflecting light Pipe outer surface 5 clearly bright from the dark environment.
- the Image signals of the camera units 3 and 3a in a helical shape Recording area 8 were assembled into an image sequence, the Brightness values pixel by pixel to determine contrasts and to recognize Contrast phenomena connected pixel by pixel - those on defects indicate - evaluated.
- an image sequence can be graphically represented as a rotation angle-scanning path diagram represent.
- a certain angle of rotation has a number n of Recording lines on.
- the scanning distance characterizes the length of the recording lines.
- a comparison of the brightness value is made per pixel 18 along each recording line of the pixel 18 with an image field 19 surrounding it. With that you can Determine differences in brightness - i.e. contrasts - relative to the surroundings.
- the Image field 19 accompanies each pixel 18 to be read in the image sequence as a moving one Benchmark.
- the extent A of contrasts K xy which are connected pixel by pixel is determined to determine contrast phenomena.
- a comparison of the contrast K xy and its extent A with a predefined contrast limit value K m and by means of one or more shape and size of the contrast phenomenon characterizing the extent limit value A m is then carried out. If the predefined contrast limit value K m and the expansion limit value A m are exceeded, an error location message is output. Similarly, if the predefined contrast limit value K m and the expansion limit value A m are not reached, an error location message is not output.
- Flaws on the outer surface 5 of a tube 1 can thus be identified recognize reliably and quickly.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
Description
- Figur 1
- eine schematische Darstellung einer Einrichtung zur optischen Qualitätsprüfung einer Rohraußenoberfläche,
- Figur 2
- eine schematische Darstellung der Anordnung einer als Zeilenkamera ausgebildeten Kameraeinheit mit Lichtquelle,
- Figur 3
- eine prinzipielle Darstellung der Fehlerstellenerkennung im optischen Dunkelfeld,
- Figur 4
- eine graphische Darstellung der Bestimmung des Kontrastes in einer aufgenommenen Bildsequenz zur Detektion von Kontrasterscheinungen und
- Figur 5
- einen allgemeinen Algorithmus, welcher der Fehlererkennung zugrundeliegt.
- 1
- Rohr
- 2
- Rotationsgestell
- 3
- Kamerseinheit
- 4
- Umlenkspiegel
- 5
- Rohraußenoberfläche
- 6
- Lichtquelle
- 7
- Aufnahmesektor
- 8
- Aufnahmebereich
- 9
- Schleifringeinheit
- 10
- Datenverarbeitungseinrichtung
- 11
- Signalumwandlungseinheit
- 12
- Auswerteeinheit
- 13
- Ausgabeeinheit
- 14
- Speichereinheit
- 15
- Steuereinheit
- 16
- Tangente
- 17
- Achse
- 18
- Pixel
- 19
- Bildfeld
Claims (7)
- Einrichtung zur optischen Qualitätsprüfung einer Rohraußenoberfläche insbesondere hinsichtlich Längsriefen und sonstigen Oberflächenfehlern, wie Schalen und Kratzer,
dadurch gekennzeichnet,
daß mindestens eine optisch auf die Rohraußenoberfläche (5) ausgerichtete und an einem Rotationsgestell (2) befestigte Kameraeinheit (3) äquidistant um das zu prüfende Rohr (1) rotiert und gleichzeitig eine Rohrtransporteinrichtung das Rohr (1) längs transportiert, wobei der dabei entstehende schraubenlinienförmige Aufnahmebereich (8) der Kameraeinheit (3) als Bildsequenz einer nachgeschalteten Datenverarbeitungseinrichtung (10) zugeht, die Fehlerstellen auf der Rohraußenoberfläche (5) erkennt und hinsichtlich der Relevanz auswertet. - Einrichtung nach Anspruch 1,
dadurch gekennzeichnet,
daß die Datenverarbeitungseinrichtung (10) eine Signalumwandlungseinheit (11) umfaßt, die die Bildsequenzdaten pixelweise mit dem zugehörigen Helligkeitswert Hxy aufbereitet und einer nachfolgenden Auswerteeinheit (12) zur Verfügung stellt, die anhand eines Fehlererkennungsalgorithmus durch Auswertung des Helligkeitsverlaufes im Aufnahmebereich (8) die relevanten Fehlerstellen feststellt, wobei eine Ausgabeeinheit (13) zumindest zwei Ausgabewerte generiert, von denen ein Ausgabewert ein positives Prüfergebnis und ein anderer Ausgabewert ein negatives Prüfergebnis kennzeichnet. - Einrichtung nach Anspruch 1,
dadurch gekennzeichnet,
daß genau zwei Kameraeinheiten (3, 3a) vorgesehen sind, die gegenüberliegend am Rotationsgestell (2) befestigt sind. - Einrichtung nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet,
daß das Rotationsgestell (2) geschützt in einem bruchsicheren Gehäuse untergebracht ist. - Einrichtung nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet,
daß die Datenverarbeitungseinrichtung (10) eine Speichereinheit (14) umfaßt, in der mehrere Grenzparameter verschiedener Rohrtypen hinterlegt sind, wovon je nach zu prüfenden Rohrtyp zugeordnete Parameter auswählbar sind, die zumindest der Auswerteeinheit (12) zur Verfügung stehen. - Einrichtung nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet,
daß die von der Ausgabeeinheit (13) der Datenverarbeitungseinrichtung (10) generierten Ausgabewerte einer Steuereinheit (15) einer Rohrprüfanlage als Eingangswert dienen. - Einrichtung nach einem der vorstehenden Ansprüche,
dadurch gekennzeichnet,
daß die Steuereinheit (15) als speicherprogrammierbare Steuerung (SPS) ausgebildet ist.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19843208 | 1998-09-16 | ||
DE19843208 | 1998-09-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0992789A1 true EP0992789A1 (de) | 2000-04-12 |
Family
ID=7881686
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99250305A Withdrawn EP0992789A1 (de) | 1998-09-16 | 1999-09-02 | Einrichtung und Verfahren zur optischen Qualitätsprüfung einer Rohraussenoberfläche |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0992789A1 (de) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110346379A (zh) * | 2019-08-22 | 2019-10-18 | 合肥工业大学 | 一种轴承缺陷探伤装置及轴承缺陷探伤方法 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4249081A (en) * | 1979-11-01 | 1981-02-03 | Sparton Corporation | Defect detection system |
WO1991008476A1 (en) * | 1989-11-30 | 1991-06-13 | Marposs Società per Azioni | Apparatus and method for inspecting linear elements |
US5266806A (en) * | 1991-07-25 | 1993-11-30 | Oca Applied Optics, Inc. | Transmission damage tester |
EP0841560A2 (de) * | 1996-11-07 | 1998-05-13 | Hewing GmbH | Vorrichtung zur optischen Untersuchung der Oberfläche von Rohren |
-
1999
- 1999-09-02 EP EP99250305A patent/EP0992789A1/de not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4249081A (en) * | 1979-11-01 | 1981-02-03 | Sparton Corporation | Defect detection system |
WO1991008476A1 (en) * | 1989-11-30 | 1991-06-13 | Marposs Società per Azioni | Apparatus and method for inspecting linear elements |
US5266806A (en) * | 1991-07-25 | 1993-11-30 | Oca Applied Optics, Inc. | Transmission damage tester |
EP0841560A2 (de) * | 1996-11-07 | 1998-05-13 | Hewing GmbH | Vorrichtung zur optischen Untersuchung der Oberfläche von Rohren |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110346379A (zh) * | 2019-08-22 | 2019-10-18 | 合肥工业大学 | 一种轴承缺陷探伤装置及轴承缺陷探伤方法 |
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