Method and apparatus for optical measurement of threads

Abstract

Method and device for optically measuring a thread on at least one end of a metal pipe (3) by means of at least one measuring head (10) which is fastened on a manipulator and which is preferably freely positionable relative to the metal pipe (3), the measuring head having at least one optical measuring zone (16) for measuring the thread and at least one position detector, wherein the method comprises at least the following method steps: A) providing the metal pipe (3) in a measuring position; B) determining the spatial position of the longitudinal axis (2) of the metal pipe (3) by means of the at least one position detector before and / or during positioning the measuring head (10) in the measuring position; C) aligning the measuring head (10) parallel to the longitudinal axis (2) of the metal pipe (3) before and / or during positioning the measuring head (10) in the measuring position; and D) carrying out an optical thread measurement.

Description

Technical Field

[0001] The present invention relates to a method for optically measuring the thread at at least one end of a metal pipe using at least one measuring head fastened to a manipulator and freely positionable relative to the metal pipe.

[0002] The present invention also relates to an apparatus for optically measuring threads, and particularly for performing the method. Background Technology

[0003] Pipe fittings used for transporting pressurized fluids (such as natural gas or oil) and connected to each other in a pressure-resistant, gas-tight, and liquid-tight manner are subject to stringent sealing requirements. In the case of such oil-specific tubing (OCTG, Oil Country Tubular Goods) used as casing or risers for oil or gas exploration wells, or for gas or oil transportation pipelines, tapered threads with undercut thread flanks are typically used. At the end of the fitting, a sealing lip is usually attached to the thread. Both the thread and the sealing lip must meet the highest precision requirements. In the prior art, it is generally known to perform optical measurements of the thread for quality control of the fitting.

[0004] For example, a method and apparatus for optically measuring the external thread profile of a pipe fitting are known from patent document WO 2019 / 09371A1. The apparatus includes a support for the pipe fitting to be measured and an optical measuring unit having at least one measuring device, comprising a light source and a camera arranged in the optical path of the light source for recording a shadow image of the external thread profile. The optical measuring unit is rigidly arranged on a support element held to pivot about three spatial axes. The optical measuring unit also has at least two measuring devices whose optical paths intersect each other. The method includes: arranging the pipe fitting to be measured on the support such that the spatial axes extend transversely to the measuring plane of the measuring unit, and the external thread is arranged in the optical path between the light source and the allocated camera; orienting the measuring unit such that the measuring plane is perpendicular to the spatial axes; recording a shadow image of the external thread by means of the camera with at least one measuring device; and evaluating the shadow image.

[0005] For example, another device for measuring threads is known from patent document EP 3 465 079 B1. This device includes: a retainer for releasably holding a pipe fitting, wherein threads are formed at the end of the pipe fitting; a first optical measuring area having a first optical sensor, wherein the first optical measuring area is mounted to an actuator of the device, the actuator being configured to move the first measuring area relative to the pipe fitting, and wherein the first optical measuring area is adjustable about a first adjustment axis relative to the thread axis of the thread; wherein a second optical measuring area of ​​the device having a second optical sensor is arranged at the actuator, wherein the optical measuring areas together form a measuring channel for simultaneously measuring the opposite side of the thread. A key feature of the device is that, by means of the actuator, the measuring channel can be tilted about at least one second adjustment axis relative to the thread axis, allowing the measuring channel to be freely oriented within a solid angle range.

[0006] A method and apparatus for optically measuring the profile of an external thread at the end of a pipe fitting are known from patent document DE 10 2007 017 747 A1, wherein the thread is generated in advance in a cycle on a production line, and the thread is continuously measured from beginning to end on the production line before further processing. The profile of the previously generated thread is illuminated tangentially to the cross-section of the pipe fitting by a relative motion consisting of rotation and translation between the pipe fitting and at least one optical measuring unit, which comprises an illuminator and a camera arranged in a backlight.

[0007] Further prior art is known from patent document EP 2 259 015 B1, which describes a combination of tactile and optical measurements of pipe threads.

[0008] Finally, a method for cleaning and subsequently measuring the tooth flank of a thread is known from patent document EP 2 799 809 B1.

[0009] When measuring threads, the metal pipe to be measured is typically placed in a measurement position where the orientation of the thread in space is not precisely defined. This is because the pipe to be measured has tolerances relative to straightness, or if the pipe is not supported along its entire length, the end of the pipe will sag due to gravity. This can impair the accuracy and reproducibility of the measurement. Summary of the Invention

[0010] Therefore, the objective of this invention is to provide a method and apparatus for optical thread measurement that improves the accuracy and reproducibility of the measurement results. Furthermore, the method and apparatus according to the invention should be easily and accurately adapted to measuring different threads on metal pipes of different diameters.

[0011] The objective is achieved by a method having the features of claim 1. The objective is also achieved by an apparatus having the features of claim 10. Advantageous designs of the method and apparatus according to the invention are given in the dependent claims.

[0012] According to a first aspect of the present invention, a method is proposed in which a measuring head can be freely positioned relative to a metal tube and the measuring head has at least one optical measuring area and at least one position detector, wherein the method includes at least the following method steps:

[0013] A) Provide metal tubing at the measurement location;

[0014] B) Determine the spatial position of the longitudinal axis of the metal fitting using the at least one position detector before and / or during the approach of the measuring head to the metal fitting;

[0015] C) Orient the measuring head parallel to the longitudinal axis of the metal fitting before and / or during positioning the measuring head in the measuring location; and

[0016] D) Perform optical thread measurement.

[0017] The method features A) to D) listed above are preferably performed in the order listed, wherein the order of method steps B) and C) can be interchanged.

[0018] According to the invention, the at least one position detector is arranged on the measuring head such that when the measuring head approaches the thread to be measured or the metal fitting to be measured, the position detector is positioned at the front end of the measuring head with respect to the adjustment path traversed by the measuring head toward the metal fitting to be measured. In this manner, the measuring head can also be oriented parallel to the longitudinal axis of the metal fitting during approach to the thread, for example, by correspondingly controlling the tightening of an inherent manipulator of the measuring head.

[0019] In a preferred variation of the method according to the invention, another method step is proposed, which includes precisely orienting the measuring head and / or the measuring area of ​​the measuring head at a specific and given angle and / or at a specific axial position with respect to the longitudinal axis of the metal fitting in the measuring location.

[0020] A first linear laser is set as a position detector, which is preferably perpendicular to the target direction of the longitudinal axis of the metal pipe or to the preset linear adjustment orientation of the measuring head.

[0021] The method according to the invention specifies that the spatial position of the longitudinal axis of the metal tube is determined and / or the measuring head and / or the at least one optical measuring area is precisely oriented by using at least one second linear laser on the measuring head, wherein the second linear laser is oriented to a target orientation parallel to the longitudinal axis of the metal tube.

[0022] The measuring head may also include a third linear laser or optical cutting sensor, which is configured to measure the thread flank or flank angle of the thread.

[0023] Furthermore, it can be specified, for example, that the diameter of the metal fitting is measured and / or calculated during the positioning of the measuring head to the measuring position. The diameter of the metal fitting can be determined directly, for example, by means of the optical measuring area of ​​the measuring head.

[0024] In another advantageous variation of the method according to the invention, the roundness of the metal tube is determined along a predetermined target orientation of its longitudinal axis during the rotation of the measuring head. Due to thread cutting processes, for example in machining centers, the metal tube to be machined may be non-round or have a partially elliptical outer contour after the machining process. According to the invention, this non-roundness can be determined during a specific angle of rotation of the measuring head around the longitudinal axis of the metal tube, for example, by means of at least one linear laser and / or by means of at least one optical measuring area.

[0025] In a variation of the method according to the invention, the deviation between the actual thread depth and the target thread depth on the circumference of the metal pipe is measured by means of at least one, preferably two, optical measuring areas during a rotation of the measuring head around the target direction of the longitudinal axis of the metal pipe of at least 180°. A total of 360° thread scan can be generated by means of two optical measuring areas arranged opposite each other when the measuring head rotates approximately 180° around the target direction of the longitudinal axis of the metal pipe.

[0026] The angular offset between the actual orientation of the longitudinal axis of the metal pipe and the target orientation of the longitudinal axis can also be calculated from the deviation of the thread depth on the circumference of the metal pipe.

[0027] The measuring head and / or measuring area can be adjusted for precise orientation relative to a carrier, which can be secured to the free end of a manipulator. Preferably, the measuring head is first positioned in the measuring location by correspondingly controlling the manipulator, such as an industrial robot configured with an articulated arm mechanism capable of movement in multiple degrees of freedom. Precise alignment of the measuring head, more precisely the optical measuring area, is preferably performed by adjusting the measuring head relative to the carrier, wherein the measuring head is preferably both linearly adjustable and oscillating relative to the carrier. The measuring head is preferably oscillating about an axis extending toward the target direction, substantially perpendicular to the longitudinal axis of the metal fitting.

[0028] In a particularly advantageous variation of the method according to the invention, the measuring head has two measuring zones, which preferably extend substantially parallel to each other and spaced apart by a distance adjustable about the longitudinal axis of the metal fitting, wherein the distance is preferably automatically adjusted according to the desired and / or calculated diameter of the metal fitting. In this way, the device according to the invention can be calibrated particularly easily for different fitting diameters. The calibration can be performed, for example, based on a test piece arranged in the measuring station.

[0029] Another method step preferably includes manually and / or automatically adjusting at least one optical measuring zone around an axis perpendicular to the longitudinal axis of the metal fitting so as to adapt the measuring head to a given thread helix angle.

[0030] Furthermore, when positioning the measuring head in the measurement position, collision recognition is preferably provided regarding the diameter and position of the metal fitting. If a potential collision between the measuring head and the metal fitting is detected, the collision recognition prevents further movement of the measuring head and / or the manipulator. This prevents damage to sensitive measuring electronics caused by impact forces.

[0031] Finally, in a variation of the method according to the invention, the identification of contamination in at least one optical measurement area is provided, preferably automatically. Depending on the detected degree of contamination, a cleaning process can be initiated or the measurement process can be functionally interrupted. If the degree of contamination, for example, of the glass cover of a sensor or light source, increases, the degree of blurring can be determined by a corresponding sensor in the form of so-called grayscale recognition. In this method, it is specified that the glass cover is cleaned automatically, for example, pneumatically. Additional cleaning processes can be introduced depending on the degree of contamination. Once a preset degree of contamination is reached, measurements can no longer be reliably performed. In this case, canceling the measurement process is meaningful. The optical sensor of the measurement area can be designed, for example, as a CCD sensor or a CMOS sensor.

[0032] Another aspect of the invention relates to an apparatus for optically measuring threads on at least one end of a metal pipe fitting, particularly an apparatus for performing the aforementioned method. The apparatus may include at least one measuring head, guided on a manipulator and freely positionable relative to the metal pipe fitting, the measuring head having at least one optical measuring area for measuring the thread and at least one position detector, wherein the measuring head is linearly adjustable and / or pivotally secured about an axis relative to a carrier fastened to the manipulator, and the at least one optical measuring area extends substantially perpendicular to the linear adjustment path of the measuring head, wherein the apparatus further includes means for adjusting and / or calibrating the measuring head and / or the measuring area of ​​the measuring head at the measurement location.

[0033] For example, at least one linear driver and / or at least one rotary driver may be provided as devices for adjusting and / or calibrating the measuring head, and these devices may be controlled accordingly by a control device.

[0034] Suitablely, an industrial robot with an articulated arm having multiple degrees of freedom is used as a manipulator.

[0035] At least one first linear laser is provided as a position detector, which extends approximately at right angles to the linear adjustment path of the measuring head.

[0036] Preferably, at least one collision detector is provided, which prevents the adjustment of the measuring head and / or the movement of the manipulator if there is a risk of collision between the measuring head or a component of the measuring head and the metal pipe. At least one linear laser in the position detector can also simultaneously function as a collision detector.

[0037] The measuring head suitably includes at least one first optical measuring area and a second optical measuring area, which extend substantially perpendicular to the linear adjustment path of the measuring head. The measuring head may, for example, have at least two legs arranged at a distance from each other and adjustable relative to each other. At least one optical sensor and at least one light source arranged at a distance therefrom are respectively disposed in these legs, each forming an optical measuring area. The optical sensor of one measuring area may, for example, be configured as a CMOS sensor or a CCD sensor and have telecentric optics.

[0038] The optical path between the optical sensor and the light source does not necessarily have to extend in a straight line; instead, it can be deflected by at least one mirror. This allows for a relatively compact construction of the measuring head. In particular, it reduces the distance of each measuring zone from the longitudinal axis of the pipe, and thus reduces the radius of rotation around the longitudinal axis of the metal pipe.

[0039] Preferably, at least one optical measuring area, or more precisely, at least one leg of the measuring head, can swing laterally to the linear adjustment path of the measuring head relative to the other corresponding measuring areas. In this way, the position of the measuring head, or more precisely, the measuring area, can be preferably automatically adjusted to and / or adapted to different thread helix angles. Attached Figure Description

[0040] Preferred embodiments of the method and apparatus according to the present invention will now be explained with reference to the accompanying drawings.

[0041] in:

[0042] Figure 1 A perspective view of the measuring head according to the invention during thread measurement is shown;

[0043] Figure 2 A side view of a laser for position detection pre-installed at the measuring head is shown in the schematic diagram.

[0044] Figure 3a A diagram illustrating the optical measurement principle according to the present invention is shown in a view along the longitudinal axis of the metal tube.

[0045] Figure 3b A side view shows the optical measurement principle with an additional optical section sensor for measuring the flank face of the undercut thread; and

[0046] Figure 3c A schematic diagram of the measurement principle is shown when measuring the flank of an undercut thread. Detailed Implementation

[0047] Figure 1 An apparatus for optically measuring threads according to the present invention is schematically shown. The apparatus includes a robot 8 acting as a manipulator, comprising a rotatable and oscillating robot arm 9 having preferably five degrees of freedom, with a measuring head 10 arranged at the free end of the robot arm. The measuring head 10 includes a carrier 11 having an optical measuring device disposed thereon for optically measuring the external thread 4 disposed on a metal tube 3. The external thread 4 of the metal tube 3 has previously been cut on a machine tool (not shown), such as a CNC milling machine or machining center. The metal tube 3 is then, as... Figure 1 As shown, it is securely fastened in the designated measurement position. Figure 1 As schematically shown, the measurement position can be defined, for example, by a positioning roller 13 (i.e., a diabolo roller) that contracts centrally on the roller conveyor 12, wherein the contraction of the positioning roller 13 determines the position of the metal tube 3. Alternatively, a lateral stop can be provided to fix the position of the metal tube 3 to be measured. In the measurement position of the metal tube 3, if necessary after the diameter of the metal tube 3 is calibrated, the carrier 11 of the measuring head 10 is moved to the measurement area in which the measuring head 10 is oriented relative to the metal tube.

[0048] The diameter calibration of the measuring head 10 is used to position the measuring device of the measuring head 10 relative to the carrier 11, so that the metal tube 3 is between the measuring devices, and so that the measuring head 10 does not collide with the metal tube 3 during pre-orientation. For this purpose, a gauge 18 is arranged in the measuring station as a reference member, which can be used to calibrate the measuring head 10 before performing the measurement process.

[0049] To position or pre-orient the measuring head 10, at least one position detector may be provided on the measuring head 10 according to the present invention, the position detector being positioned when the measuring head 10 moves to... Figure 1The spatial position of the longitudinal axis 2 of the metal fitting 3 is determined before and / or during the measurement position shown. The actual orientation of the longitudinal axis 2 of the metal fitting 3 may differ from the target orientation of the longitudinal axis 2. In order to detect the actual orientation of the longitudinal axis 2 of the metal fitting 3, the measuring head 10 includes a first linear laser 6 and a second linear laser 7 as position detectors, by means of which the orientation of the measuring head 10 relative to the metal fitting 3 fastened in the measurement position can be checked and, if necessary, corrected.

[0050] Figure 2 The arrangement of the first linear laser 6 and the second linear laser 7 on the measuring head is schematically shown. The first linear laser 6 extends at approximately a 90° angle relative to the target orientation of the longitudinal axis 2 of the metal tube 3, or at a 90° angle relative to the linear adjustment path of the measuring head 10. The second linear laser 7 extends generally parallel to the target orientation of the longitudinal axis 2 of the metal tube 3, or parallel to the target orientation of the longitudinal axis of the second metal tube 3, or parallel to the linear adjustment path of the measuring head 10. The second linear laser 7 is positioned at the height of the target position of the longitudinal axis 2 of the metal tube 3 on the non-wobbly leg 19 of the measuring head 10.

[0051] The method includes both the pre-orientation of the measuring head 10, i.e., positioning the measuring head 10 by correspondingly controlling the robot arm 3 to... Figure 1 The measurement position shown also includes precise orientation of the measuring head 10 in the measurement position by adjusting the measuring head 10 relative to the carrier 11. This precise orientation includes pivoting the measuring head about a swing axis 1 extending generally transversely to the longitudinal axis 2 of the metal tube 3 to orient at least one measurement area 16 relative to the longitudinal axis 2 of the metal tube 3.

[0052] As described above, the measuring head 10 can move linearly relative to the carrier and preferably oscillate about at least one axis. Linear adjustment can be achieved, for example, by means of at least one driven ball screw or by means of at least one pin-gear transmission unit (Triebstock). Adjustment about the oscillation axis 1 can be achieved, for example, by means of an electric rotary actuator (not shown).

[0053] Measuring devices for measuring the external thread 4 are respectively arranged in the legs 19 of the measuring head 10. The spacing between the legs 19 of the measuring head 10 is linearly adjustable. The legs 19 of the measuring head 10 form a U-shaped enclosure of the metal tube 3. Both legs can be configured to be independently adjustable relative to each other. In the described embodiment, one leg 19 of the measuring head 10 is fixedly positioned, while the other leg 19 of the measuring head 10 is adjustable relative to its opposite leg 19. To adjust the measuring head 10 to accommodate different thread pitches, the legs 19 of the measuring head 10 are pivotable relative to each other about an axis transverse to the linear adjustment path of the measuring head 10.

[0054] As a measuring device, a camera 14 with telecentric optics and a light source 15 positioned opposite the camera are disposed in each leg of the measuring head 10, such as... Figure 3a As exemplarily shown, camera 14 and light source 15 are respectively arranged opposite each other with a gap to form a measurement area 16, wherein the measurement area 16 can be constructed as a straight measurement area 16. Alternatively, the optical path between camera 14 and light source 15 can be redirected by a mirror.

[0055] The following is a reference Figure 3a , Figure 3b and Figure 3c To explain the measurement principle, each measurement zone 16 detects a portion of the external thread profile on one side of the metal pipe fitting. The projection of a portion of the external thread 4, generated by the light source 15, appears on a photosensitive sensor (e.g., a CMOS sensor or a CCD sensor) arranged in the camera 14, using telecentric optics. The use of a telecentric objective lens at the camera 14 ensures that the projection detected by the corresponding sensor is recorded without distortion and to the correct scale. The measurement data of the external thread 4 detected in this way is recorded and compared with the target profile of the external thread 4. Two measurement zones 16 can form a single measurement channel.

[0056] In a variant of the measuring head 10 according to the invention, the measuring head includes at least one optical section sensor 17, which is configured as a laser optical section sensor and oriented toward the thread flank 5 of the external thread 4. Figure 3c The measurement of the thread facet 18 is shown in the figure.

[0057] The measurement data of the external thread profile and / or the sealing lip of the external thread 4 are evaluated in the regulator (not shown), and control commands for controlling the machine tool 2 are derived, especially when there is a deviation between the target profile and the actual profile recorded by the measurement data. The corresponding target profile can be freely selected from a catalog of different thread types, for example, in the operator interface (HMI).

[0058] The measuring head 10 and the control of the machine tool form a preferably closed adjustment loop. Control commands can be, for example, adjusting the tool position, selecting the tool, the machine tool chuck, and the rotational speed and applied torque of the metal pipe 3, performing tool changes, changing the cycle time of the machine tool 2, etc. The adjustment can be configured as a self-learning adjustment (KI), and for this purpose can include at least one adjustment algorithm. According to the invention, the measurement data obtained regarding the pipe is used not only for feedback and control of the machine tool, but also for protecting and tracking quality data.

[0059] List of reference numerals in the attached diagram:

[0060] 1. Swing axis of the measuring head

[0061] 2. Longitudinal axis of metal pipe fittings

[0062] 3. Metal pipe fittings

[0063] 4 External threads

[0064] 5. Thread flank

[0065] 6 First linear laser

[0066] 7. Second linear laser

[0067] 8 robots

[0068] 9. Robot Arm

[0069] 10 Measuring Head

[0070] 11. Carrier

[0071] 12 roller conveyors

[0072] 13 Positioning rollers

[0073] 14 cameras

[0074] 15 Light Sources

[0075] 16 Measurement Area

[0076] 17 Optical Section Sensor

[0077] 18 Gauges

[0078] 19. The legs of the measuring head.

Claims

1. A method for optically measuring a thread on at least one end of a metal pipe (3) by means of at least one measuring head (10), which is fastened on a manipulator and can be positioned relative to the metal pipe (3), the measuring head having at least one optical measuring zone (16) for measuring the thread and at least one position detector, wherein, The method includes at least the following steps: A) Provide the metal fitting (3) at the measurement location; B) Determine the spatial position of the longitudinal axis (2) of the metal fitting (3) by means of the at least one position detector before and / or during positioning the measuring head (10) in the measuring position; C) Orient the measuring head (10) parallel to the longitudinal axis (2) of the metal tube (3) before and / or during positioning the measuring head (10) in the measuring position; as well as D) Perform optical thread measurement. Its features are, During the linear motion of the measuring head (10) along the target orientation of the longitudinal axis (2) of the metal tube (3), the spatial position of the longitudinal axis (2) of the metal tube (3) is determined by using at least one first linear laser (6) as a position detector and by using at least one second linear laser (7) on the measuring head to determine the spatial position of the longitudinal axis (2) of the metal tube (3) and / or to precisely align the measuring head (10) and / or the optical measuring area (16), wherein the second linear laser is parallel to the target orientation of the longitudinal axis (2) of the metal tube.

2. The method of claim 1, wherein, The method has another method step, which includes precisely oriented the measuring head (10) and / or the measuring area (16) of the measuring head (10) at the measuring location at a specific and given angle relative to the longitudinal axis (2) of the metal fitting (3) and / or at a specific axial orientation.

3. The method according to claim 1 or 2, characterized in that, The first linear laser (6) is oriented at right angles to the target orientation of the longitudinal axis (2) of the metal tube (3) on the measuring head (10).

4. The method according to claim 1 or 2, characterized in that, The roundness of the metal fitting is determined along a predetermined target direction on the longitudinal axis of the metal fitting during the rotation of the measuring head.

5. The method according to claim 1 or 2, characterized in that, During the rotation of the measuring head (10) at least 180° around the target orientation of the longitudinal axis (2) of the metal tube (3), the deviation between the actual thread depth and the target thread depth on the circumference of the metal tube (3) is measured by means of the optical measuring area (16).

6. The method according to claim 5, characterized in that, The angular offset between the actual orientation of the longitudinal axis of the metal pipe (3) and the target orientation of the longitudinal axis (2) of the metal pipe (3) is calculated from the deviation of the thread depth on the circumference of the metal pipe (3).

7. The method according to claim 1 or 2, characterized in that, The measuring head (10) and / or the measuring area (16) can be adjusted to be precisely oriented relative to the carrier (11).

8. The method according to claim 1 or 2, characterized in that, The measuring head (10) has two measuring areas (16) that extend at a certain distance from each other. The distance between the two measuring areas can be adjusted about the longitudinal axis (2) of the metal pipe (3), wherein the distance is adjusted according to the diameter of the metal pipe (3) as determined and / or calculated.

9. The method according to claim 1 or 2, characterized in that, The method includes another method step of manually and / or automatically adjusting at least one optical measuring area (16) about an axis perpendicular to the longitudinal axis (2) of the metal fitting (3) to adapt the measuring head to a given thread helix angle.

10. The method according to claim 1 or 2, characterized in that, The method includes another method step, which includes collision identification of the measuring head (10) that prevents further movement of the measuring head (10) and / or the manipulator.

11. The method according to claim 1 or 2, characterized in that, The method includes another method step of identifying contamination in at least one optical measurement area (16) and initiating a cleaning process or a functional interruption of the measurement process based on the detected degree of contamination.

12. An apparatus for optically measuring the thread at at least one end of a metal pipe fitting (3), which is an apparatus for performing the method according to any one of claims 1 to 11, the apparatus comprising at least one measuring head (10) guided on a manipulator and freely positionable relative to the metal pipe fitting (3), the measuring head having at least one optical measuring area (16) for measuring the thread and at least one position detector, wherein, The measuring head is linearly adjustable and / or oscillatingly secured about an axis relative to a carrier (11) fastened to the manipulator, and the at least one optical measuring area (16) extends perpendicular to the linear adjustment path of the measuring head (10), wherein the device further includes means for adjusting and / or calibrating the measuring head and / or the measuring area (16) of the measuring head (10) in the measuring position, characterized in that at least one first linear laser (6) is provided as a position detector, the first linear laser extending perpendicular to the linear adjustment path of the measuring head (10) and a second linear laser (7) is additionally provided as a position detector, the second linear laser extending parallel to the linear adjustment path of the measuring head (10).

13. The apparatus according to claim 12, characterized in that, An industrial robot with an articulated arm (9) having multiple degrees of freedom is set up as a manipulator.

14. The apparatus according to claim 12 or 13, characterized in that, At least one collision detector is also provided, which prevents the adjustment of the measuring head (10) and / or the movement of the manipulator if the measuring head (10) or a component of the measuring head (10) may collide with the metal tube (3).

15. The apparatus according to claim 12 or 13, characterized in that, The measuring head (10) has first and second optical measuring areas (16), which extend perpendicularly to the linear adjustment path of the measuring head (10).

16. The apparatus according to claim 12 or 13, characterized in that, The measuring head (10) has at least two legs (19) arranged at a certain distance from each other and adjustable relative to each other. At least one optical sensor and at least one light source arranged at a certain distance from the optical sensor are respectively provided in the at least two legs. The optical sensor and the light source respectively form an optical measuring area (16).

17. The apparatus according to claim 12 or 13, characterized in that, At least one of the optical measurement areas (16) is capable of swinging laterally to the linear adjustment path of the measuring head (10) relative to the corresponding other optical measurement areas (16).

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