Method for detecting weld seam geometry

Abstract

A technique for sensing a weld seam geometry of a plastic butt weld seam, preferably plastic pipes, including: manual positioning of an optical sensor in relation to a butt weld seam between pipeline components, preferably plastic pipes, wherein the sensor is aligned approximately perpendicularly to the pipe centre axis, automatic approaching of the sensor of measurement positions along or around a sensor axis, acquiring the visible weld seam geometry and/or the data by means of the sensor in each approached measurement position, determining the optimum measurement position by way of the acquired data, preferably by means of an algorithm, automatic approaching of the sensor of the optimum measurement position along or around the sensor axis, acquiring the weld seam geometry to determine the quality of the weld seam, analyzing and judging the measurement of the acquired weld seam geometry at the optimized measurement position.

Claims

1. A method for sensing a weld seam geometry of a plastic butt weld seam between adjacent pipes each having a central axis, comprising: pre-positioning a sensor using the following steps (a)-(g): (a) positioning an optical sensor at a given position wherein-the sensor is displaced from the butt weld seam but where the sensor is aligned approximately perpendicularly to the pipe central axis, (b) automatically moving the sensor longitudinally along the pipe central axis from the given position to a first different measurement position displaced from the butt weld seam longitudinally along the pipe central axis, (c) acquiring visible weld seam geometry data by the sensor in the first measurement position, (d) automatically moving the sensor longitudinally along the pipe central axis from the first measurement position to a second measurement position; (e) acquiring visible weld seam geometry data by the sensor in the second measurement position, (f) determining an optimum measurement position (opt. M) by way of the acquired data at the first measurement position and the second measurement position, (g) automatically moving the sensor longitudinally along the pipe central axis to the optimum measurement position (opt. M), and (h) after the sensor has been moved to the optimum measurement position, then: (i) acquiring the weld seam geometry data from the sensor while remaining at the optimum measurement position to determine quality of the weld seam, and (j) analyzing and judging the measurement of the acquired weld seam geometry data at the optimum measurement position.

2. The method according to claim 1, wherein the sensor is moved to at least three different measurement positions to acquire visible weld seam geometry.

3. The method according to claim 1, wherein a weld seam width (B) and/or the K dimension (K) are acquired by the sensor in each measurement position.

4. The method according to claim 1, wherein an algorithm determines the optimum measurement position (opt. M) by way of acquired weld seam widths (B) and/or K dimensions (K), wherein the optimum measurement position (opt. M) is the position at which the smallest weld seam width (B) and/or the smallest K dimension (K) and no image distortion is present.

5. The method according to claim 1, wherein an algorithm for determining the optimum measurement position on the basis of the acquired data is defined by a polynomial.

6. The method of claim 1 wherein the sensor is moved to different measurement positions to capture information about sides of the weld seam.

7. A device for carrying out the method according to claim 1 containing an optical sensor and a carrier device, wherein the carrier device has a drive and a sensor axis for positioning of the sensor, wherein the sensor axis extends perpendicularly to the pipe central axis and the sensor is movable round the sensor axis.

8. The device according to claim 7, wherein the sensor is designed as a camera and has an objective lens.

9. The device according to claim 7, wherein the drive is designed as a stepping motor having a spindle.

10. The device according to claim 7, wherein the drive has a position sensing unit and is connected to a controller.

Description

DRAWINGS

(1) The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

(2) FIG. 1 shows a schematic illustration of the arrangements of the device according to the invention for carrying out the method according to the invention during the approach of measurement positions using a standard objective lens,

(3) FIG. 2 shows a schematic illustration of the arrangements of the device according to the invention for carrying out the method according to the invention in optimum measurement positions using a standard objective lens,

(4) FIG. 3a shows a recording of the sensor in an optimum measurement position,

(5) FIG. 3b shows a recording of the sensor in a measurement position for determining the optimum measurement position,

(6) FIG. 4 shows a longitudinal section through a pipe having a weld seam,

(7) FIG. 5 shows a schematic illustration of the acquired measurement position and an optimum measurement position thus determined,

(8) FIG. 6 shows a three-dimensional view of a device according to the invention,

(9) FIG. 7 shows a schematic illustration of the arrangements of the device according to the invention for carrying out the method according to the invention during the approach of measurement positions using a telecentric objective lens, and

(10) FIG. 8 shows a schematic illustration of the arrangements of the device according to the invention for carrying out the method according to the invention in optimum measurement positions using a telecentric objective lens.

DETAILED DESCRIPTION

(11) Example embodiments will now be described more fully with reference to the accompanying drawings.

(12) The drawing illustrated in FIG. 1 shows a schematic illustration of a device 1 according to the invention. In this position of the sensor 5, different positions along the sensor axis 7 are approached in order to acquire the weld seam geometry, preferably the weld seam width B and/or the K dimension K. The difference between the recorded images of the sensors 5 can be seen well from FIGS. 3a and 3b. FIG. 3b shows a recording in which the sensor 5 is not positioned at the optimum measurement position opt. M, i.e., centrally in front of the weld seam, and thus the resulting width B and the K dimension K are greater. Such recordings are recorded at at least three positions along the sensor axis 7, which is the minimum of acquired measured data to determine and/or compute the optimum measurement position. By way of the known distance of the sensor 5 from the pipe 11 and the aperture angle 9 of the objective lens and of the two acquired visible edges 2 of the weld seam 3, the weld seam width B and/or where the optimum measurement position opt. M can be recorded without distortion of the width and/or of the K dimension K results, which is then used for analyzing the weld seam quality.

(13) It is shown in FIG. 2 when the sensor 5 is positioned in the optimum measurement position for recording the weld seam geometry, which is used for analyzing and judging the seam. It can be seen well that the sensor 5 and/or the optical axis 6 is/are oriented centrally to the weld seam, whereby a parallax can be avoided, which is relevant in the analysis and judgement of the weld seam quality.

(14) FIG. 4 shows a welded pipe 11 in which the weld seam 3 is shown in sections in order to show which dimension, in addition to the weld seam width B, namely the K dimension K, is also used for determining the optimum measurement position. This dimension K can be determined separately instead of the width B, or also in combination.

(15) FIG. 5 shows diagrams in which the determined measurement points for determining the optimum measurement position are shown as crosses. These were acquired during the approach to the different positions along the sensor axis, with which the optimum measurement position opt. M was then preferably determined on the basis of an algorithm. The vertical axis B/K shows the measured dimension of the width of the weld seam B or of the K dimension K of the weld seam and the horizontal axis shows the corresponding position x of the sensor on the sensor axis or the angle setting on the sensor axis.

(16) In the first diagram, it is recognizable that the optimum measurement position opt. M can also be defined by the intersection of two straight lines, which can be determined on the basis of the measurement points.

(17) Alternatively, the method is represented by means of a polynomial, which does not extend exactly through the measurement points but rather approximately through the measurement points. It can thus occur that a determined measurement point lies lower than the lowest point of the polynomial curve. In such a case, the lower single point is preferably used as the optimum measurement point opt. M, wherein the lowest point lies on the curve in the second diagram in FIG. 5 and the single point is arranged slightly higher. The last diagram in turn shows a polynomial curve which extends precisely through the measurement points.

(18) In FIG. 6, the device 1 according to the invention is illustrated three-dimensionally, wherein it is shown independently of a pipe here. The device 1 has a carrier device 8 on which a drive 10 is arranged and which has a sensor axis 7 for accurate positioning of the sensor 5. The sensor 5 is preferably designed as a camera having a corresponding standard objective lens here, wherein a telecentric objective lens can also be used, but the arrangement of the sensor axis of the drive is then slightly changed.

(19) The schematic figures shown in FIGS. 7 and 8 correspond to FIGS. 1 and 2 but with a telecentric objective lens instead of a standard objective lens. It is clearly apparent in this case that in a telecentric objective lens, the field of vision extends cylindrically and therefore an offset and/or an image distortion is/are corrected by a pivoting of the sensor 5 on the sensor axis 7, so that the optical axis 6 is then oriented perpendicularly to the pipe central axis 4 in the optimum measurement position opt. M. However, in this embodiment, the weld seam does not have to be located in the centre of the field of vision of the sensor.

(20) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.