JP5142775B2 - Welding quality inspection method and apparatus - Google Patents

Description

  The present invention relates to a welding quality inspection method and apparatus for indexing and evaluating welding quality with respect to arc welding of a butt joint.

Conventionally, there has been a method of obtaining a bead surface shape using a light cutting method with a laser measuring device after welding construction and evaluating welding quality.
Patent Document 1 discloses a weld bead shape inspection method for obtaining a bead surface shape after welding by a light cutting method and estimating welding quality.

However, even if only the shape of the beads formed after welding is observed, if there is an effect such as gaps, misinterpretations, or groove processing depth variations that existed before welding, always make a legitimate evaluation. I can't.
For example, the surface of a bead that is well welded with a standard groove even when the groove is too deep and a gap remains in the groove bottom or a spherical weld defect such as a blow hole occurs inside the weld metal. If there is no difference from the shape, it is determined that the welding quality is good.
Further, it may not be possible to cope with bead-shaped variations caused by groove-shaped variations.

Patent Document 2 discloses a welding quality inspection method for measuring a welded part shape before and after welding.
In a large-sized welded structure, groove processing is performed by gas cutting, so that the dimensional accuracy is poor, and a non-uniform gap is generated in the welded portion, so that the welding quality cannot be evaluated by uniform judgment criteria.
In the disclosed method, the shape of the gap before the welding operation is measured to know the state of the gap, and a judgment criterion in consideration of the size of the gap is used so that proper judgment of the welding quality can be performed. Therefore, the disclosed method cannot perform quality evaluation that reflects the state of penetration or the back bead.

In particular, in butt welding of pipes, the bead appearance shape is affected by variations in groove processing, misalignment of the butt position called misalignment, poor roundness of the outer shape of the pipe, bending of the pipe, etc. May not be evaluated correctly. In addition, since good welding cannot be performed unless the wire feed amount is adjusted depending on the welding position, the welding metal supply amount differs depending on the position, and the appropriate bead shape also differs. It is difficult to estimate.
JP-A-5-087539 JP 2001-038467 A

  Therefore, the problem to be solved by the present invention is to provide a welding quality inspection method and apparatus capable of performing a welding quality evaluation reflecting a defect element inside a welded portion. In particular, the present invention provides a welding quality inspection method and apparatus capable of performing welding quality evaluation at the arc welding portion of a butt joint at the time of welding construction.

  In order to solve the above problems, the welding quality inspection method of the present invention uses a surface shape measuring instrument to measure the groove surface shape before welding and the bead surface shape after welding, and welds the welded portion from the difference in shape between the two. Calculate the metal amount, estimate the weld metal supply amount based on the welding wire supply amount obtained by the welding wire feed amount measuring device, calculate the ratio of the weld metal amount to the weld metal supply amount, that is, the welding index, and display it The welding index is displayed on the vessel as an indicator of welding quality.

  The welding quality inspection apparatus of the present invention includes a surface shape measuring instrument that measures the surface shape of a welded portion, a welding wire feed amount measuring device that measures the feed amount of the welding wire, an arithmetic device, and a display device. Welding wire feed amount measured by a welding wire feed amount measuring device by measuring the groove surface shape before welding and the bead surface shape after welding and calculating the weld metal amount of the weld from the shape difference between the two. The weld metal supply amount is estimated based on the above, the ratio of the weld metal amount to the weld metal supply amount, that is, the welding index is calculated, and the ratio is displayed on the display.

  In the welding quality inspection method and the welding quality inspection apparatus of the present invention, the amount of deposited metal that fills the groove portion by welding work is determined from the surface shape measurement results before and after welding, and the amount of deposited metal obtained and the feed amount of the welding wire Calculate and display the ratio to the weld metal supply obtained from the above, clarify the amount of increase or decrease in the amount of deposited metal relative to the weld metal supply, and the amount of metal leaking from the groove and forming the back bead, or welding Appropriate welding quality evaluation can be performed by grasping voids such as blow holes generated in the metal.

  In addition, since the feed length of the welding wire supplied at the time of welding construction can be easily measured by the wire feed amount measuring instrument attached to the wire feeding device, the wire feed amount is known using the wire diameter. be able to. Further, the amount of welding wire supplied to the welding quality inspection position can be calculated by taking the welding speed into consideration.

Furthermore, the proportion of the metal remaining welded to the welded portion of the welding wire varies depending on the type of welding wire and the welding method, and can be evaluated in advance as the welding efficiency. For example, in the non-consumable electrode type welding method such as TIG welding, the welding efficiency is 1, and in the consumable electrode type welding method such as MIG welding, when the amount scattered by sputtering is taken into account, the welding rate is less than 1.
In the weld quality evaluation per unit width at the evaluation position, the weld metal supply amount obtained by using the measured wire feed amount, welding speed, wire diameter, and welding efficiency is used.

If the ratio of the amount of deposited metal calculated from the surface shape before and after welding, that is, the welding index, is 0.8 to 1.0, the welding quality is good from experience. Although it may be, it can be estimated that when 1.0 or more, there is an abnormality having a void such as a blow hole inside the weld metal, and when 0.8 or less, there is an abnormality in which an excessive back bead is generated.
As described above, according to the method of the present invention, the welding index is quantitatively expressed by a relatively simple calculation, and accurate welding quality evaluation can be performed.

The welding quality inspection method or apparatus of the present invention may further display a result of calculating the difference between the ideal bead shape designated in advance and the bead shape after welding.
In this method, when there is a defect inside the weld metal, the bead surface shape is locally depressed, and when sputtered particles are attached, a protrusion is formed. Therefore, in addition to the evaluation based on the weld metal supply amount of the weld wire, the bead surface Introduced to determine the quality of the bead appearance from the shape data and to ensure complete quality evaluation.

  The surface shape measuring device extracts a slit-shaped light portion from a light-projecting device that irradiates slit-shaped light, an imaging device that photographs slit-shaped light irradiated on the surface of an object, and an image acquired by the imaging device. It is an optical processing surface shape measuring device that measures the surface shape from the optical cutting surface contour line that is formed in the surface shape by irradiating the measurement object with slit light. preferable. Various commercially available three-dimensional digitizers can also be used.

By using the welding quality inspection method or apparatus of the present invention, stable welding quality evaluation can be performed regardless of the groove processing accuracy. Further, defects such as blow holes generated in the weld metal can be detected, and the quality of the penetration and the back bead can also be accurately estimated.
Furthermore, the quality estimation can be automated using the welding quality inspection method or apparatus of the present invention, and a stable inspection can be performed at a low cost.

Hereinafter, based on an Example, the welding quality inspection method and device of the present invention are explained in detail using a drawing.
FIG. 1 is a block diagram illustrating the configuration of the present embodiment, FIG. 2 is a flowchart illustrating a measurement process in the present embodiment, FIG. 3 is a graph illustrating an example of proper welding measured by applying the present embodiment, and FIG. FIG. 5 is a graph showing a measurement example when the bead is excessive, FIG. 5 is a graph showing a measurement example when the appearance is poor, and FIG. 6 is a flowchart showing another example of the measurement process in this embodiment.

  As shown in FIG. 1, the welding quality inspection apparatus according to the present embodiment includes a general-purpose robot 10 that holds a welding torch 14, a robot controller 12 that controls the robot 10, and a laser sensor 20 that serves as a detection unit of the shape measuring instrument. And a laser sensor controller 22 that receives the output of the laser sensor 20 and outputs a measurement result, and a wire feeding device that is attached to the wire feeding device 16 that feeds the welding wire to the welding torch 14 and measures the wire feeding amount. It is comprised from the supply measuring device 30, and the computer 40 which inputs a measurement result from the robot controller 12, the laser sensor controller 22, and the wire supply measuring device 30, and performs various arithmetic processing.

In the present embodiment, the present invention is applied to the general-purpose robot 10, but it goes without saying that the present invention can also be applied to an automatic welding machine as long as the inspection position and the welding conditions at that position can be matched.
The computer 40 performs data processing related to groove shape data and bead shape data, processing of data collected by the wire feed measuring device 30, and collection of welding conditions from the robot controller 12 or the like.

This embodiment is intended for TIG welding with a butt groove of a pipe.
FIG. 2 is a flowchart for explaining the inspection procedure in the case of calculating the amount of deposited metal by the cross-sectional area.
The laser sensor 20 is moved to the inspection target position at the pipe end first abutted (S10).
Subsequently, the pipe is rotated to collect groove shape data for one round (S11).

  The laser sensor 20 is configured to irradiate an object with slit-shaped laser light, photograph the slit light appearing on the surface with a CCD camera, and send the acquired image to the laser sensor controller 22. The slit light on the surface of the object is a light cutting line that represents a surface contour line when cut in a plane in the irradiation direction.

The laser sensor controller 22 obtains the surface contour of the groove portion on the laser light irradiation surface from the light cutting line supplied from the laser sensor 20. The surface contour data obtained by moving the measurement object or moving the laser sensor 20 relative to the measurement object can be accumulated and used as the surface shape data of the groove portion.
The camera of the laser sensor 20 may be one that obtains a contour line directly with a two-dimensional CCD camera, or obtains a two-dimensional image by moving the one-dimensional CCD camera in a direction perpendicular to the welding line. May be.

The surface shape data collected and arranged by the laser sensor controller 22 is transmitted to the computer 40.
The computer 40 may be a general-purpose computer that includes an input / output device, a storage device, a computing device, a display device, and the like, and that is capable of executing a computer program that executes the welding quality inspection method of this embodiment.
The calculator 40 converts the data so as to correct misunderstandings from the received surface shape data (S12), and compensates for variations in the step even when there is a step that changes with rotation. The correction of the misunderstanding can be performed, for example, by extracting the shoulder portion of the groove and correcting both shoulders sandwiching the groove so as to have the same height. In order to calculate the difference from the bead surface shape later and regard it as the amount of weld metal, it is preferable to compensate for the inclination of the axial surface of the pipe by data conversion.

  As a conversion method, there is a method in which the left and right groove shoulders are inclined and the groove shape data is rotated by an inclination angle. Further, when the rotation angle is sufficiently small, a method can be used in which a straight line passing through the left and right groove shoulder positions is drawn and the height direction coordinate in the groove shape is calculated based on this straight line.

  Next, welding is performed, and the wire feed amount in the vicinity of the inspection target position is measured (S13). The wire feeding amount can be measured from the number of rotations of a roller that is rotated by wire feeding by sandwiching a fed wire with a non-slip roller. Further, in a wire feeding device that feeds back and controls the wire feeding amount, the wire feeding amount can be determined by a feeding amount command value for the control device.

A weld metal supply amount per unit width at the welding quality inspection position is calculated from the wire feed amount, the wire diameter, the welding speed, and the welding efficiency (S14).
The welding efficiency means the ratio of the amount of weld metal remaining after welding to the welded portion out of the total amount of welding wire supplied to the welded portion. For example, the welding efficiency is 1 in a non-consumable electrode type welding method such as TIG welding. On the other hand, in the consumable electrode type welding method such as MIG welding, if the amount scattered by sputtering is taken into account, the welding rate is less than 1.
In the consumable electrode type welding method, the welding efficiency varies depending on the type and brand of the welding wire, and is 0.90 to 0.98 for a solid wire, 0.85 to 0.95 for a flux-cored wire, and the like. As described above, the welding efficiency varies depending on the type of welding wire and the welding method, but can be given in advance.

The laser sensor 20 is moved to the inspection target position (S15), and the bead surface shape data of the inspection target position is acquired by the same method as when the groove surface shape data is acquired (S16). The bead surface shape data at the inspection position can be acquired even during or after the welding process. In addition, it is possible to reduce the time by performing measurement while returning to the welding start position after the end of welding.
Even if the pipe butt is deformed by welding, it is necessary to accurately estimate the weld metal amount, so that the misunderstanding is corrected based on the acquired bead surface shape data (S17). The correction of the misunderstanding is performed, for example, by detecting the left and right weld toe positions and calculating the surface coordinates of the weld metal using a straight line connecting the left and right weld toes as a reference line. Even when the axial surface of the pipe is tilted, it does not match the groove shape, and the amount of weld metal calculated based on the difference between the two shapes becomes inaccurate. Preferably it is done.

The difference between the groove surface shape data and the bead surface shape data, which compensates for the workpiece displacement and inclination and the workpiece deformation due to welding, is calculated, and the cross-sectional area of the weld metal deposited at the inspection position is calculated (S18). .
FIG. 3 is a graph in which groove surface shape data A and bead surface shape data B are superimposed and plotted for a butt joint of a pipe having high weld quality. The weld metal welded corresponds to the portion sandwiched between the two curves A and B.

Next, the difference in the surface shape with respect to the weld metal supply amount per unit width obtained based on the wire feed amount obtained from the wire feed amount measuring device previously, that is, the value obtained by multiplying the cross-sectional area by the unit thickness. As a result, the ratio of the amount of deposited metal is calculated (S19). In this specification, this ratio is called a welding index.
When the welding index is calculated, it is possible to determine pass / fail on the basis of values determined from experience, for example, 0.8 and 1.0 (S20).

For example, if the welding index is 0.8 or less, a defect such as a back bead is estimated (S21). FIG. 4 shows a lower plot of the bead surface shape data B than that in FIG. 3 even though the same amount of weld metal was supplied to the groove represented by the groove surface shape data A as in FIG. It is thought that the cause is that the weld metal has melted or that the back bead is formed excessively.
When the welding index is 1.0 or more, it can be considered that the surface is raised by the presence of weld defects in the weld metal such as blow holes, and it can be determined that the welding is defective (S22).
These estimation results are displayed on the display device (S27).

Also, if the welding index is 0.8 to 1.0, it is considered good, but there may be an abnormality in the surface shape, so it is preferable to inspect the bead surface shape to confirm that there is no shape defect. .
Therefore, the quality of the weld quality is evaluated by comparing the bead surface shape data with the reference bead surface shape data that makes the ideal shape (S23) and comparing the absolute value of the difference with a predetermined value (S24).

Since the bead shape changes when the groove shape changes or the gap changes, the ideal bead shape is not single. Therefore, if the reference shape is prepared as a template, it is necessary to prepare a very large number of reference shapes and select a reference shape that meets various conditions for each inspection object.
In the welding quality inspection method according to the present embodiment, a procedure is adopted that can perform reliable quality estimation without the need to prepare reference bead surface shape data as a template in advance.

FIG. 5 is a graph illustrating a method for evaluating the bead surface shape in comparison with the standard shape.
The groove surface shape data A was obtained by measuring the groove portion, and the bead surface shape data B was obtained by measurement after welding.
From the bead surface shape data B, the weld toe is specified, and a total of four points are taken at two points on each of the left and right points from the toe, and four points are passed from the coordinate data of the four points represented by the circles. A smooth curve such as a next curve is set as reference bead surface shape data C.

If the difference D between the measured bead surface shape data B and the reference bead surface shape data C is taken and there is a portion where the difference D is larger than a predetermined value, for example, ± 0.3 mm, pits, undercuts, surplus A welding defect appearing on the surface shape, such as an excessive size, is estimated (S25). If the absolute value of the difference D between the bead surface shape data B and the reference bead surface shape data C is 0.3 mm or less, it can be determined that there is no problem in the welding quality (S26).
These evaluation results are displayed on the display device (S27).

As described above, since the reference bead surface shape C is determined based on the measured bead surface shape data B, the surface shape abnormality can be reliably detected without preparing a large number of templates.
The method of forming the reference surface shape data C based on the measurement result of the surface shape is not limited to the above method, and for example, using three or more coordinate points on the bead surface shape data B taken at an appropriate interval. An appropriate approximation method such as a method of making the reference surface shape data C by drawing an approximate curve can be used.
Furthermore, the evaluation of the difference D between the measured bead surface shape data B and the reference surface shape data C also uses various error evaluation methods such as a method of integrating the deviations of the two and a method of integrating the errors by squaring. be able to.

  The method for measuring the amount of beads welded to the groove includes, for example, an optical three-dimensional digitizer (3D digitizer) in addition to the method of calculating based on the surface shape obtained from the light cutting surface as described above. There is also a method in which the volume is directly measured using a general-purpose three-dimensional measuring device such as a difference between before and after welding.

When using a 3D digitizer, measure the bead surface shape after welding and the groove surface shape before welding for the measurement region including the inspection region, and based on the difference between the bead surface shape data and the groove surface shape data in the inspection region. Calculate the amount of deposited metal in the inspection area.
The welding quality inspection apparatus using a 3D digitizer differs from the configuration shown in FIG. 1 only in that the laser sensor 20 and the laser sensor controller 22 are replaced with a 3D digitizer.

The inspection procedure of the welding quality inspection apparatus directly calculates the volume of the deposited metal in the inspection region using the 3D shape measurement data of the 3D digitizer instead of obtaining the surface shape as 2D information from the optical cut surface data. However, other procedures are the same as those described above with reference to FIG.
FIG. 6 is a flowchart for explaining a welding quality inspection procedure using a 3D digitizer.

In the welding quality inspection procedure using the 3D digitizer, first, the 3D digitizer is moved to the inspection target portion (S30), and three-dimensional groove surface shape data is collected for the portion including the inspection target region (S31).
Next, welding is performed, and the wire feed amount for the region to be inspected is measured (S32). The wire feed amount can be measured by using, for example, a wire feed amount measuring device that measures the number of rotations of a roller that rotates by wire feeding.
From the wire feed amount, the wire diameter, the welding speed, and the welding efficiency, the weld metal supply amount for the region to be inspected is calculated (S33).

The 3D digitizer is moved to the inspection target portion (S34), and the three-dimensional shape data of the bead surface at the inspection target position is acquired (S35).
The three-dimensional groove surface shape data and the three-dimensional bead surface shape data in the inspection target region are compared, and the volume of the weld metal welded to the inspection target region is calculated (S36).
The ratio of the weld metal welded to the amount of weld metal supplied to the inspection target area is calculated to obtain a welding index (S37).

When the welding index is calculated, pass / fail is determined using predetermined values such as 0.8 and 1.0 as threshold values (S38).
For example, if the welding index is 0.8 or less, the defect is that the back bead is excessive (S39), if the welding index is 0.8 to 1.0, the welding quality is good (S40), and the welding index is 1.0 or more. If it is, it can be determined as a weld defect (S41) inside the weld metal.
These estimation results are displayed on the display device (S42).

Note that the welding quality inspection method and inspection apparatus of the present invention can be applied to each layer in the lamination welding to obtain a high quality welding quality in the lamination welding.
Needless to say, the present invention can be applied to fillet welded joints and lap joints in addition to pipe butt joints.

As described in detail above based on the embodiments, the welding quality inspection method and inspection apparatus of the present invention enable stable welding quality evaluation regardless of the groove processing accuracy. Further, it is possible to estimate defects such as blow holes generated in the weld metal. Furthermore, the quality of penetration and back bead can also be evaluated.
In addition, by applying the welding quality inspection method and inspection apparatus of the present invention, it is possible to automate quality evaluation, thereby reducing welding costs and stabilizing inspection.

It is a block diagram explaining the structure of the welding quality inspection apparatus in one Example of this invention. It is a flowchart which shows the measurement process in a present Example. It is a graph which shows the surface shape data in the example of appropriate welding measured by applying a present Example. It is a graph which shows the example of a measurement when the back bead measured by applying this example is excessive. It is a graph which shows the example of a measurement in the case of the appearance defect measured by applying a present Example. It is a flowchart which shows another example of the measurement process in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Robot 12 Robot controller 14 Welding torch 16 Wire feeding apparatus 20 Laser sensor 22 Laser sensor controller 30 Wire feed amount measuring device 40 Computer

Claims (8)

  At the arc welded part of the butt joint, the groove shape before welding and the bead shape after welding are measured using a surface shape measuring instrument, and the amount of deposited metal in the welded part is calculated from the difference between the two shapes, and the welding wire is fed. A welding quality inspection method, comprising: measuring a weld metal supply amount by a welding wire with a quantity measuring device; calculating a ratio of the weld metal amount to the weld metal supply amount; and displaying the ratio on a display.   2. The welding quality inspection method according to claim 1, further comprising comparing an ideal bead shape designated in advance with the bead shape after welding, calculating a difference between the two, and displaying the result.   2. The surface shape measuring instrument is an optical cutting surface shape measuring instrument that measures a surface shape from a light cutting surface contour line formed in a surface shape by irradiating a measuring object with slit light. Or the welding quality inspection method of 2.   The welding quality inspection method according to claim 1, wherein the surface shape measuring instrument is a three-dimensional digitizer that outputs three-dimensional shape data of an object.   A surface shape measuring instrument that measures the surface shape of the welded portion, a welding wire feed amount measuring device that measures the feed amount of the welding wire, an arithmetic device, and a display device, and the surface shape measuring instrument at the inspection target portion The groove surface shape before welding and the bead surface shape after welding are measured, and the arithmetic unit calculates the amount of deposited metal deposited on the weld from the difference in shape between the two, and the welding wire feed meter measures the welding wire. The feed amount is measured, the arithmetic unit calculates the weld metal supply amount based on the weld wire feed amount, and further calculates the ratio of the weld metal amount to the weld metal supply amount. Welding quality inspection device that displays the ratio.   Furthermore, a storage device for storing the ideal bead shape in a form that can be compared with the measured bead shape is provided, and the arithmetic unit calculates the difference between the ideal bead shape and the measured bead shape and displays the result. The welding quality inspection device according to claim 5.   The surface shape measuring instrument includes a light projecting device that irradiates slit-shaped light, an image capturing device that photographs slit-shaped light irradiated on the surface of the inspection target portion, and an image acquired by the image capturing device. The welding quality inspection apparatus according to claim 5 or 6, wherein the welding quality inspection apparatus is a light-cutting surface shape measuring instrument configured by an image processing apparatus that extracts a portion and obtains coordinates thereof.   The welding quality inspection apparatus according to claim 5 or 6, wherein the surface shape measuring instrument is a three-dimensional digitizer that outputs three-dimensional shape data of an object.

Images