Method for optically measuring threads on the ends of metal tubes or threads on sleeves

Abstract

The invention relates to an assembly (1) and a method for optically measuring threads, in particular for measuring internal threads (12) in a sleeve or in a sleeve end of a metal tube (11), the assembly (1) comprising at least one optical sensor (5), at least one further optical element which is positionable relative to the optical sensor (5) and which is arranged on an optical bench (3) in its optical axis (7) at a specific distance from the sensor and which is configured to optically scan the internal thread (12), and means for detecting and / or storing and / or evaluating the measurement data recorded by the sensor.

Description

[Technical Field]

[0001] Book invention Yes, yes The present invention relates to a method for optically measuring threads, in particular for measuring internal threads at or within the sleeve end of a metal tube.

[0002] Pipes used to convey fluids under pressure, such as natural gas or oil, and which are screwed together in a pressure-resistant, gas-tight, and liquid-tight manner must meet high demands for tightness. In such OCTG pipes, used as casing or riser pipes for oil or gas exploration wells or natural gas or oil transmission lines, conical threads with undercut thread flanks are typically used. A sealing lip is usually attached to this thread at the end face of the pipe. Both the thread and the sealing lip must meet extremely high precision requirements. Optical thread measurement is basically known in the prior art for inspecting the quality of pipes.

[0003] A method and an apparatus for optically measuring the male thread profile of a pipe are known, for example, from WO 2019 / 09371.

[0004] WO 2012 / 069154 discloses a method and an apparatus for inspecting external threads of oil field pipes, which comprises a sensor guided on a frame, the sensor being arranged on a support with a thread, the thread of which corresponds to the thread of the pipe and surrounds a portion of the conical thread of the pipe to be inspected, the sensor being configured as a confocal sensor.

[0005] WO 2020 / 232041 also discloses an apparatus for measuring threads in oilfield pipes. The apparatus includes a sensor unit configured to measure the distance between a sensor and a portion of the thread of a metal pipe. The sensor or sensor unit can be adjusted radially and axially with respect to the internal thread of the metal pipe by a number of actuators, and a control device can generate a three-dimensional image of the internal thread from the multiple distance measurements. The sensor unit includes a confocal chromatic sensor, which is introduced into the metal pipe on a rod and then centered inside the metal pipe using a scanning roller. After the guide pole of the linkage is concentrically oriented, the sensor is adjusted within the metal pipe by both translational and rotational movements, scanning the thread. The measurement data obtained in this way is used to generate a three-dimensional image of the thread.

[0006] The assembly known from WO 2020 / 232041 is not easily adapted to pipes with small internal diameters. Tactile centering of the measurement assembly is laborious and requires a relatively large amount of structural space. The sensor's field of view is oriented at a predetermined angle relative to the longitudinal axis of the metal pipe, and the pole on which the sensor is attached can be manipulated using three different actuators. Here, an actuator is provided for rotational movement of the pole about its own longitudinal axis, an actuator for rotational movement of the pole about the longitudinal axis of the metal pipe, and an actuator for linear movement of the pole inside the metal pipe, i.e., parallel to the longitudinal axis of the metal pipe. Scanning undercut and / or conical threads is difficult with this assembly. It should be assumed that a relatively long measurement time is required to fully detect all distance information for mapping the thread.

[0007] An assembly for optically measuring holes with small inner diameters is known, for example from WO 2021 / 055736, which includes at least one optical sensor and at least one further optical element that is positionable relative to the optical sensor, arranged on the optical axis at a specific distance from the sensor, and configured to optically scan the inner diameter of the hole. Further prior art is known from the documents Korean Patent Publication No. 10-1368486, US Patent Application Publication No. 2015 / 292872, European Patent Application Publication No. 2887010, WO 2016 / 000764 and JP 10-142335 A1. Book The problem underlying the invention is to achieve relatively short measurement times. and relatively high accuracy The method as mentioned at the beginning, which allows optical measurement of, in particular, undercut and / or conical internal threads in the sleeves of oil field pipes, For those The purpose is to provide the law.

[0008] The above problem is solved by an assembly having the features of claim 1. Li So it is solved do.

[0009] According to one aspect of the present invention, The method according to the invention comprises: Assembly for optically measuring threads at the end of a metal tube, in particular for measuring internal threads at the end of a sleeve of a metal tube or internal threads in a sleeve It includes the use of , the assembly includes at least one optical sensor, at least one further optical element that is positionable relative to the optical sensor and is arranged on the optical bench in its optical axis at a specific distance from the sensor and configured to optically scan the internal thread, and further includes means for detecting and / or storing and / or evaluating measurement data recorded by the sensor.

[0010] By combining the sensor with at least one further optical element, small sensors with folded or linear configurations can be used. Particularly preferably, only one sensor with linear configuration is provided, which may be oriented, for example, in the optical axis of the system. In the assembly according to the invention, the sensor and the further optical element form a system.

[0011] The assembly according to the present invention With It is envisaged that the optical bench and / or frame is at least linearly positionable in or parallel to the longitudinal axis of the metal tube.

[0012] The sensor is , together As a focus sensor, in particular as a confocal chromatic sensor There areThese sensors are small. By combining them with other optical elements, they can be configured, for example, in a linear configuration, which makes the assembly compact and allows the measurement of internal threads with small internal diameters.

[0013] The sensor can be configured, for example, as a confocal distance sensor. In a confocal chromatic measurement system, white light is split into its wavelengths via a lens system, so that each wavelength is focused at a different, defined distance. The blue wave train is focused near the sensor, while the red wave train is focused further away from the sensor. The reflected light is collected and analyzed by interferometry. In this case, the color with the greatest intensity corresponds to each focal point and thus to the distance from the sensor to the measurement point. By detecting multiple points or distances, a thread profile of the thread to be measured can be easily generated. Such a thread profile can be detected and displayed in two or even three dimensions.

[0014] The assembly according to the present invention With It is envisaged that the optical element includes a mirror that is positionable about at least one axis.

[0015] In the assembly according to the invention, it may be provided that the optical element comprises at least one, preferably two, actuators by means of which the mirror can be pivoted about one axis or the other, respectively. The mirror may, for example, be doubly Cardan-suspended, in which case the Cardan frame may each be positionable by means of a magnetic actuator.

[0016] The assembly according to the present invention WithThe optical element is configured as a so-called galvanometer scanner, in which a mirror is rotatable and pivotable relative to the optical axis, so that at least one partial circumference of the internal thread of the metal pipe can be optically scanned. A signal detected by the mirror of the optical element is transmitted to a sensor in the optical axis of the assembly.

[0017] The sensor advantageously comprises a lens system and a control device for evaluating the signals of the lens system interferometrically. The sensor may be connected to the control device by a suitable cable, for example by means of a glass fiber cable.

[0018] Conveniently, the optical bench and / or frame is positionable using at least one linear drive.

[0019] The assembly may further include a means for centering the optical bench within the metal tube, which operates in a contactless manner.Signal detection and processing can be single-channel or multi-channel.

[0020] If the assembly includes at least one sensor bent at 90°, this sensor can provide internal centering of the assembly within the metal tube.

[0021] gold Method for optically measuring threads at the end of a metal pipe, in particular for measuring internal threads at the end of a sleeve of a metal pipe or internal threads at a sleeve The law , A) providing an optical system comprising at least one optical sensor and at least one further optical element arranged on an optical axis at a specific distance from each other; B) positioning an optical system in the longitudinal axis of the metal tube or parallel to the longitudinal axis of the metal tube, preferably inside the metal tube, or positioning the metal tube relative to a system that is fixedly arranged in the longitudinal axis of the metal tube or parallel to the longitudinal axis of the metal tube, C) scanning the internal thread during linear positioning of the optical system and / or during rotation of the optical element at an angle to the optical axis; and D) detecting and / or storing and / or processing the measured values ​​detected by the sensor. The method according to the invention makes it possible to measure two internal threads of a metal pipe or two internal threads located on opposite sides of a sleeve in one measurement run.

[0022] The screw thread can be scanned over its length and / or over at least one partial circumference by a sensor, which preferably detects distance values ​​which are converted into a two-dimensional or three-dimensional measurement image and correspondingly shown in two or three dimensions.

[0023] The optical sensor preferably comprises an optical passive sensor comprising a lens system and a control device. Preferably, the measurement signals received from the sensor are fed to a control device which performs an interferometric evaluation of the measurement signals. Data from the control device can be transferred via an interface to a computing unit, for example in the form of a computer (PC).

[0024] In the method according to the invention, it is assumed that the optical sensor and a further optical element, for example in the form of a mirror, form an optical axis. During, for example, linear adjustment of the optical sensor, the optical element can be adjustable about at least one, preferably two, preferably mutually perpendicular, axes, so that the entire thread can be scanned during the measurement run of the optical system. For this purpose, the optical sensor and the further optical element are preferably arranged on the optical axis so that they can be adjusted relative to each other.

[0025] light The optical system includes at least one galvanometer scanner. And The galvanometer scanner scans at least one partial circumferential surface of the female thread during linear position adjustment of the optical system.

[0026] Here, the circumferential contour of the thread is preferably detected and / or represented in two and / or three dimensions.

[0027] In a particularly advantageous variant of this method, automatic centering of the optical axis of the optical system within the metal tube or within the sleeve is provided. It may be assumed that during the measurement run, the optical system is arranged in a fixed position and the sleeve or sleeve end is moved over the system, or that the metal tube or sleeve is arranged in a fixed position and the measurement sensor system or the optical system is adjusted relative to the longitudinal axis of the fixedly arranged metal tube or the longitudinal axis of the fixedly arranged sleeve.

[0028] In an advantageous and convenient variant of the method according to the invention, a dark adjustment or dark calibration of the sensor is set up, which can be carried out automatically, for example by entering a darkened housing.

[0029] Furthermore, a sensor calibration can be established using a reference component with known dimensions and a known thread profile. Additionally, contamination of the optical system can be identified by comparing the optical signal intensity with stored reference values.

[0030] In a particularly advantageous variant of the method according to the invention, it is provided to use the measurement data detected by the sensors to derive control commands for open-loop and / or closed-loop control of a machine tool, e.g., a CNC machine, which is configured to produce an internal thread by cutting at least one end of a metal tube or in a sleeve. The assembly can be arranged, for example, in a production line with a thread-cutting machine and can be connected to the open-loop and closed-loop control devices of the thread-cutting machine.

[0031] The optical control commands are e.g. Derived requirements for tool wear identification and tool replacement Readjustment of the tool position, e.g. in case of incorrect setting parameters or to compensate for tool wear Tool correction based on the geometrical arrangement of the cutting insert (e.g., if steps can be identified after a tool change) Tool correction based on wear (for example, if the cutting insert begins to stain) Correction of tools based on external influences (e.g., when the ambient temperature changes) Modifying the tool based on a different starting material (for example, if the tube material becomes a different material or if the wall thickness becomes larger or smaller) Tool wear identification to optimize downtimes (e.g., when coordinating cutting speed, cutting edge geometry, feed and measurement results) Tool wear identification to predict tool failure Tool wear identification to optimize tool inventory Tool wear identification to increase productivity (e.g. by replacing tools earlier and reducing scrap generation) Increased productivity through cycle time optimization (for example, identifying whether various functions are delivering the expected added value) Increased productivity by improving material flow (for example, bottlenecks elsewhere can be identified early and then tools can be changed or cleaning operations carried out) Increased quality through early problem identification (for example, measuring a specific vibration in a thread cutting machine and then stopping this vibration during the process, closing the thread or repeating the finish cut) Improved quality by comparing measurement results with torque on sleeve thread connectors Improved quality by comparing measurement results with those of other machines (NDT (non-destructive testing): in this case magnetic particle testing) It may be.

[0032] The collected data can further be used for quality assessment and documentation and subsequent processes, and can be correlated with these machine data, for example, using corresponding regulatory control algorithms or AI. These subsequent processes and correlations can be Identifying dirt on sleeves and distinguishing it from errors Correlation of measurement data with previously collected data to detect stress locations in the sleeve, which for example lead to ovalization after threading, and therefore possibly an improvement of the hardening strategy Improved quality by comparing measurement results with torque on sleeve thread connectors -Improvement of quality by comparing measurement results with those of other machines (NDT: magnetic particle testing in this case) It may be.

[0033] Furthermore, the measuring device may have mechanical and / or optical anti-collision devices.

[0034] To detect a particular thread profile zone (eg, an undercut profile), a sensor may be positioned at a specific point within the internal thread and a partial area may be scanned by a galvanometer scanner.

[0035] In the present invention, The galvanometer mirror is used to scan the thread multiple times at different angles of light (for example, at an angle of 90°, then at 100°, then at 110°, or at 70° or 80°) and to superimpose the curves of the measurement signal. It has been The objective is to measure each thread profile zone with a sufficiently strong optical signal.

[0036] Although the present invention is primarily geared towards measuring female threads, those skilled in the art will understand that the assembly and method according to the present invention may of course also be configured for measuring male threads.

[0037] The invention will now be described by way of example with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0038] [Figure 1] 1 shows a schematic representation of an assembly according to the invention; [Figure 2] 1 shows another optical element of the assembly according to the invention as a so-called galvanometer scanner; [Figure 3] FIG. 2 is a diagram specifically illustrating the relative arrangement of optical elements and sensors. [Figure 4] FIG. 1 shows a two-dimensional thread profile created based on measured data of the assembly. [Figure 5] FIG. 1 shows a schematic representation of the assembly in relation to the sleeve end of the metal tube.

[0039] The assembly 1 shown in FIG. 1 is a test structure comprising a frame 2 with an optical bench 3 that is linearly adjustable on a running rail 4. A confocal chromatic sensor 5 and an optical element in the form of a galvanometer scanner 6 are arranged on the optical bench 3 along an optical axis 7. The galvanometer scanner 6 is configured as a mirror 9, which is doubly mounted in a cardanic manner and is adjustable by actuators about two axes oriented perpendicular to each other on a cardan element 10. The galvanometer scanner 6 and the optical sensor 5 are each adjustably arranged on a holder 8 on the optical bench 3. The adjustability of the position of the galvanometer scanner 6 and the optical sensor 5 is used for adjustment purposes. During the measurement run, the distance of the optical sensor 5 relative to the galvanometer scanner 6 along the optical axis 7 is defined and can be constant. Advantageously, both the holder 8 for the galvanometer scanner 6 and the holder 8 for the optical sensor are adjustable in height, with the purpose of adjustment perpendicular to the optical axis 7.

[0040] The galvanometer scanner 6 is shown diagrammatically in FIG. 2, from which it can be seen that the galvanometer scanner 6 has a circular mirror 9 with a relatively small diameter, which is pivotally supported in two cardan elements 10.

[0041] FIG. 3 shows the relative placement of the optical sensor 5 and the galvanometer scanner 6 in the optical axis 7 of the system.

[0042] FIG. 4 shows a two-dimensional measurement record of a recording obtained from a measurement run along the longitudinal axis of a metal tube 11 (see FIG. 5).

[0043] 5, for example, a metal tube 11 with an internal thread 12 can be arranged in a fixed position in a measurement state (not shown), while the optical bench 3 is moved on the running rails 4 into the interior of the metal tube 11, and measurement data of the internal thread 12 are recorded during the linear movement of the optical bench 3. In this case, the mirror 9 of the galvanometer scanner can be oriented at a specific angle relative to the optical axis 7. Alternatively or additionally, it can be envisaged to adjust the position of the mirror 9 relative to the longitudinal axis of the metal tube 11 during the measurement run in order to perform a partial peripheral scan of the internal thread 12.

[0044] Although the above example relates to a metal tube 11 with a sleeve end, it should be understood that the invention also allows the method to be carried out with a sleeve with two oppositely arranged internal threads.

[0045] Moreover, those skilled in the art will easily understand that this method can also be carried out on male threads.

[0046] As can be seen from the combination of Figures 4 and 5, the internal thread 12 is formed as a conical internal thread with undercut thread flanks.

[0047] The measurement data detected by the assembly 1 or the optical sensor 5 are supplied to a control device, designated by the reference numeral 13, which performs an interferometric evaluation of the optical signals. The control device 13 transfers the evaluated distance data to software running on a computer 14 in order to display a two- or three-dimensional profile, on which a digital twin of the metal pipe 11 to be measured may be mapped. [Explanation of symbols]

[0048] 1 Assembly 2 frames 3 Optical bench 4 Running rail 5 Optical Sensor 6 Galvanometer Scanner 7 Optical axis 8 Holder 9. Mirror 10 Cardan Elements 11 Metal tube 12 Female thread 13 Control equipment 14 Computer

Claims

1. A method for measuring a female thread (12) in a sleeve or a female thread (12) in a sleeve end of a metal tube (11), comprising: The method comprises: A) providing an optical system comprising at least one optical sensor (5) and at least one further optical element arranged in an optical axis (7) at a specific distance from each other; B) positioning the optical system in the longitudinal axis of the metal tube (11) or the sleeve or parallel to the longitudinal axis of the metal tube (11) or the sleeve, or positioning the metal tube (11) relative to the optical system, which is arranged in a fixed position, in the longitudinal axis of the metal tube (11) or the sleeve or parallel to the longitudinal axis of the metal tube (11) or the sleeve, C) scanning the internal thread (12) during linear positioning of the optical system and / or during rotation of the optical element at an angle to the optical axis (7); D) detecting and / or storing and / or processing the measurements detected by said optical sensor (5), In a method comprising: the optical element is formed as a scanner (6) including a mirror (9) that is positionable about two axes, the scanner (6) scans at least one partial circumferential surface of the internal thread (12) during linear position adjustment of the optical system, and the scanner (6) is configured to scan the internal thread (12) multiple times at different angles of light, and signals from the multiple scans are superimposed; characterized in that method.

2. The method of claim 1 , further comprising detecting and / or indicating a peripheral contour of the thread.

3. 3. The method according to claim 1, wherein a self-centering of the optical axis (7) within the metal tube (11) or within the sleeve is provided.

4. 3. The method according to claim 1 or 2, further comprising dark calibration of the optical sensor (5).

5. 3. The method according to claim 1, characterized by sensor calibration with a reference component.

6. 3. The method according to claim 1 or 2, characterized by the identification of contamination of the optical system by comparison of the light intensity signals detected by the optical sensor (5).

7. 3. The method according to claim 1, further comprising using the measurement data detected by the optical sensor (5) to derive control commands for open-loop and / or closed-loop control of a machine tool configured to manufacture an internal thread (12) by cutting into at least one end of at least one metal tube (11) or into a sleeve.

8. The use of an assembly (1) for measuring a female thread (12) in a sleeve or a female thread (12) in a sleeve end of a metal tube (11), characterized in that the assembly (1) comprises at least one optical sensor (5), at least one scanner (6) that is positionable relative to the optical sensor (5) and is arranged on an optical bench (3) at a specific distance from the optical sensor (5) on its optical axis (7) and configured to optically scan the female thread (12), and 3. The method according to claim 1, further comprising: means for detecting and / or storing and / or evaluating the recorded measurement data; wherein the assembly (1) further comprises at least one frame (2) for accommodating the optical bench (3), the optical bench (3) and / or the frame (2) being at least linearly positionable in or parallel to the longitudinal axis of the metal tube (11); and wherein the optical sensor (5) is formed as a confocal sensor.

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