The Xiris Blog

Cornelius Sawatzky

Recent Posts

Edge Detection for Weld Monitoring

Posted by Cornelius Sawatzky on Tuesday, June 21, 2016 @ 02:00 AM

With the advent of high dynamic range weld cameras, such as the Xiris XVC-1000, images of welding processes can be made with enormous ranges of brightness.  As a result, it is now possible to monitor and record good quality video of most welding processes using an HDR camera.  With good quality images of the weld pool, arc, and seam, the next logical step is to incorporate image processing into the camera system to extract additional information to help operators better control the welding process.

The Edge Detector tool from Xiris is a powerful edge detection and analysis utility that can detect edges, or areas of rapid contrast change, within a region of interest.  When used with a weld camera, the edge detector can help find the size and position of numerous features in a welding scene such as wire width and length, weld seam gap or center, molten pool boundaries or torch tip edge quality.

Edge_1.png

Figure 1: Edge Detector window

The Edge Detector generates a projection of intensities from a region of interest into a profile, then analyzes the profile to find presence of edges.  Each edge has a series of properties such as edge strength, expected polarity and location that can be used to measure or sort each edge so that objects in the weld environment can be analyzed.  The net result is a new way for fabricators to enhance the monitoring and controlling of their weld processes.

 Conclusion

By incorporating image processing tools such as an Edge Detector into their weld camera systems, machine builders can measure features of their weld processes in a way that has never before been possible.  It is now possible to find edges in an image, such as the weld wire, or seam, that could allow for further monitoring or analysis, or form the foundation for seam tracking or weld pool geometry analysis.

For more information on how Xiris Weld Cameras and the new Edge Detector tool can help monitor your weld processes, visit Xiris.com

Topics: weld video, Xiris, welding, High Dynamic Range, R&D, edge detection

Detecting Slag Build-up on Ferrite Casings in Pipe Mills

Posted by Cornelius Sawatzky on Tuesday, April 26, 2016 @ 02:00 AM

 A major challenge in producing good quality pipe on a welded Pipe Mill is the build-up of slag on the ferrite bundle used inside the pipe. Slag is a mixture of metal oxides and silicon dioxide that is a byproduct of separating the steel from its raw ore.  Ferrite bundles are typically placed inside the pipe to help concentrate the electrical radiation towards the seam to be welded.  During welding, slag can drip down from the molten metal at the edges of parent material, building up deposits on the ferrite bundle casing surface inside the pipe.  The result is a potential reduction in power concentration at the weld point, which could lead to weakened pipe welds.  Known as a “Ferrite breakdown”, it needs to be identified early in the weld process in order to avoid poor welds from making their way down the line or out the door to the customer.

Ferrite_Bundle.pngFerrite Bundle for large Pipe

(courtesy www.piecsa.mx)

 One obvious solution would be to periodically stop the mill and open up the pipe and visually inspect the casing; this of course is not always a feasible or desirable solution.  A better approach to identify changes over time is by monitoring the shape of the weld bead. This can be done by operators who might visually inspect the scarf coming off the tube for signs of change and or abnormalities.  However, as slag could build up on the surface of the ferrite bundle casing which is inside the welded pipe, it is difficult for the operator to notice any slag buildup.

A better solution would be to use a laser based profile measurement system such as the Xiris WI3000.  By using a precise laser with a high speed camera, multiple images of the weld bead and its immediate area can be taken.  The shape of the weld bead can then be automatically analyzed for potential defects.

If there is slag buildup on the surface of the ferrite casing and less power makes it to the seam of the pipe, the top of the weld bead may become flatter or even concave as a result of reduced weld power concentration.  Visually it may appear to the operator as a “pasty” weld and we like to call it a “freeze line” defect.

When monitoring the weld bead using a laser profile of the weld zone complemented with some real time geometrical measurements, the operator can be alerted to the freeze-line condition defect much sooner.  As seen in the picture below taken from the screen of a WI3000, the operator is provided with a magnified view of the weld zone readily visible from afar.  In this view the weld bead is starting to flatten and if it becomes concave, the operator would be alerted before a potential faulty weld is generated.

 

Screenshot.png

Screenshot from the Xiris WI3000 Laser Inspection System

The shape of the weld bead on an ERW pipe mill can provide much information.  In particular, if a laser based profile measurement tool is used, such as the WI3000 from Xiris, early detection of defects such as freeze line can be made.  Such defects often occur as a result of a reduction of power making its way to the weld zone resulting in incomplete heating of the weld bead. By providing early warning of such defects, operators can correct the problem before it becomes a critical failure.

For more information on how WI3000 can help reduce ferrite breakdown in your tube mill, visit Xiris.com

Topics: quality control, weld camera, Laser welding, Xiris, welding, High Dynamic Range, weld pool, productivity, slag buildup

Post-Secondary Schools Increase Trade Resources and Improve Student Experience

Posted by Cornelius Sawatzky on Wednesday, July 02, 2014 @ 04:16 PM

Technical trade schools and welding education programs are not new to post-secondary institutions, but as organizations see an increase in admissions, there is also a noticable increase in demand for equipment. This is not only to appease the quantity of new students, but also to ensure safety and efficiency in the curriculums. The most appealing program to a student will have experienced and knowledgeable professors, interesting and extensive material, as well as modern equipment. However, even with all of these tools there are still some major factors that all of these institutions face:

  • The booths to demonstrate and instruct welding are too small for more than just a few students at a time
  • The instruction area has inadequate space for the number of students registered in the program
  • The welding consumables budget is insufficient and will not cover the cost for new equipment

When instructing such a unique trade, it is important that students not only understand what is being taught, but can see the demonstration. Being able to see and understand what is occurring with a weld tip and arc, as well as the environment around it (weld seam, weld pool, shielding gas, and wire feed) are all essential elements to understanding the welding process. Without a grasp on these elements and factors, there is little that can be retained by the student. This is all based on a visual demonstration that can be hard to provide in many welding institution settings.

As technology and equipment advance, the ability to record lessons and welds adds an immense benefit to both students and instructors. Students can learn more outside of the classroom, as well as retain and digest all of the important elements of the lesson using video playback. This can be provided through the addition of weld cameras.

teach paper resized 600

Not any camera can be placed in such a hostile environment, and expected to function normally. Therefore, more research and development has been contributed to constructing a small, clear, and functional camera that can withstand this environment, and provide the best image quality. Xiris Automation Inc. has created such a camera, called the XVC-O (Xiris View Camera for Open Arc Welding). This allows video recording, clear images, storing/saving capabilities, as well as better classroom visuals for welding programs. This live weld feed can be attached to a simple monitor (as demonstrated above), or even a full size projector, and still provide a clear, comprehensive view of all elements. Xiris has also developed a version for submerged arc welding.

Local colleges, such as Conestoga College, have added this kind of technology to their budding trades programs. As the Government of Canada announced this May, they are investing $2.3 million over the next five years towards Conestoga College’s new Centre for Smart Manufacturing establishment. Already using the XVC-O, these improvements have allowed Conestoga to become an extremely competitive College in the area, and one of the most competitive for the welding trade school industry. Other institutions, such as NAIT (Northern Alberta Institute of Technology) have also added systems to their curriculum and have noticed great improvements. NAIT’s Chair of Welding Programs, Chris Manning says “by displaying the captured welding video on a remote screen, the instructors can vastly improve the learning experience of their students, with improved learning success, which is always the instructor’s goal”.

For more information about how welding cameras can assist welding education please visit www.xiris.com.

 

Topics: quality control, weld camera, weld camera, weld inspection, Machine Vision, camera placement, field of view, welding instruction, Education, Welding Process, weld video, Xiris, welding, Conestoga College, NAIT

Monitoring Tube and Pipe Production to Find SCARFING Defects

Posted by Cornelius Sawatzky on Tuesday, June 17, 2014 @ 12:53 PM

Recent advancements in machine vision technology have made a new type of inspection able to see defects related to the forming and welding area of a tube or pipe.  The result is improved quality assurance and process control on the production line.  The new type of inspection device is a laser-based triangulation system that measures the outside contour of a tube or pipe in the vicinity of its weld. 

Typically NDT systems are placed at the end of a production as a final check.  However, the laser inspection system can be placed directly after the weld box.  This system can let operators know what is changing in their welding process, allowing them to perform corrective action before significant scrap occurs. This capacity is especially helpful for one of the most common defects found across all types of Tube manufacturing: Tube Scarf defects.

 

The Scarfing Width

In certain situations on ERW/HF tube and pipe production lines, there is not enough space to perform the Non Destructive Inspection (NDI) measurements right after the weld box because the scarf tool (used to remove excessive bead from the tube) is placed directly after the weld box.  In such situations, the measurement process must be made after the scarfing tool, measuring the flat area of the tube where the scarf has occurred. On some production lines, this measurement is essential to identify the shape and profile of the tube, and to understand how it is travelling through its forming process.

Known as the scarf width, this measurement is defined as the length of the “flat” portion of the tube that appears after the weld bead has been removed by scarfing.  Scarf width measurement changes quickly during production, so it is best averaged over a number of inspections in order to make the measurement stable.

 June 17.14 Blog Scarfing resized 600

The Scarf Width, where “w” = the width of the defect.

How the WI2000p System Measures the Scarf Width

Xiris Automation Inc. has developed a non-destructive inspection system called the WI2000p Weld Inspection System. The WI2000p includes a laser line and a camera whose optical axis is offset to the axis of the laser line by an “offset angle”.  The WI2000p creates a visible cross-section of the tube by projecting the laser line on to the tube and capturing an image of the line using the camera.  The resulting image shows a profile of the tube surface as if it were cut in cross section.  If a tube is ideally round, the laser image will represent a section of an ellipse and any anomaly such as a freeze line defect can be mathematically detected. 

The WI2000p bases all of its measurements on the differences between the actual laser profile line seen by the camera, and the ideal mathematical profile based on the tube parameters.  By knowing the position of the actual laser profile, the ideal profile, and the size of the pixels in the image, the WI2000p can detect weld bead profile defects that often escape detection by other quality tools such as Eddy Current testing, or Ultrasonic Testing techniques

 

Conclusion

Overall, laser-based 3D imaging systems, such as the WI2000p from Xiris, offer an excellent measurement option for tube mill owners/operators who want additional, real-time monitoring of weld features. They can be used in a proactive manner, warning operators what is changing in their welding process so that they can perform corrective action before significant scrap occurs And by measuring the outside contour of a weld, laser-based 3D imaging systems can operate on any type of material, regardless of its reflectance or magnetic properties, using a single head to perform the measurement.

Topics: quality control, weld camera, weld inspection, Laser welding, image processing, High Dynamic Range, Tube and Pipe welding, laser-based monitoring, Pipe Cladding, welding defect, scarfing

Monitoring Tube and Pipe Production to Find FREEZE LINE Defects

Posted by Cornelius Sawatzky on Tuesday, June 03, 2014 @ 03:09 PM

Recent advancements in machine vision technology have made a new type of inspection able to see defects related to the forming and welding area of a tube or pipe.  The result is improved quality assurance and process control on the production line.  The new type of inspection device is a laser-based triangulation system that measures the outside contour of a tube or pipe in the vicinity of its weld. 

Typically NDT systems are placed at the end of a production as a final check.  However, the laser inspection system can be placed directly after the weld box.  This system can let operators know what is changing in their welding process, allowing them to perform corrective action before significant scrap occurs. This capacity is especially helpful for one of the most common defects found across ERW Tube manufacturing:  Freeze Line defects in the weld bead. 

 

The Freeze Line Defect

Particularly in Electric Resistance Welding (ERW) or High Frequency (HF) welding processes, incomplete heating of the faces of the parent material can sometimes occur, resulting in a potentially cold-welded joint, which manifests itself as a line or seam extending from the top surface of a weld down into the welded area, in the shape of a sharp valley. Such a defect could indicate major metallurgical or structural problems in a weld, such as cold welding or improper forming.  It can very often be a point of a major failure of a weld in high-stress applications because the freeze line acts as a crack initiator into the welded material.  The Freeze Line becomes a concern to weld operators when it goes below the surface of the parent material of the tube because once the weld bead has been removed through grinding or scarfing, there is a risk that a void of non-welded material could be left behind.

The freeze line is measured from the lowest point of any contour in the weld bead to the surface of the parent material as defined by the ideal circle scribed by the walls of material beyond the weld zone.  If the freeze line goes below a pre-defined height, then it is considered a defect.

June 3.14 Blog Freeze Line resized 600

The Freeze Line Defect, where “h” = the height of the defect.

 

How the WI2000p System Measures the Freeze Line Defect

Xiris Automation Inc. has developed a non-destructive inspection system called the WI2000p Weld Inspection System. The WI2000p  includes  a laser line and a camera whose optical axis is offset to the axis of the laser line by an “offset angle”.  The WI2000p creates a visible cross-section of the tube by projecting the laser line on to the tube and capturing an image of the line using the camera. The resulting image shows a  profile of the tube surface as if it were cut in cross section.  If a tube is ideally round, the laser image will represent a section of an ellipse and any anomaly such as a freeze line defect can be mathematically detected. 

The WI2000p bases all of its measurements on the differences between the actual laser profile line seen by the camera, and the ideal mathematical profile based on the tube parameters.  By knowing the position of the actual laser profile, the ideal profile, and the size of the pixels in the image, the WI2000p can detect weld bead profile defects that often escape detection by other quality tools such as Eddy Current testing, or Ultrasonic Testing techniques

 

Conclusion

Overall, laser-based 3D imaging systems, such as the WI2000p from Xiris, offer an excellent measurement option for tube mill owners/operators who want additional, real-time monitoring of weld features. They can be used in a proactive manner, warning operators what is changing in their welding process so that they can perform corrective action before significant scrap occurs And by measuring the outside contour of a weld, laser-based 3D imaging systems can operate on any type of material, regardless of its reflectance or magnetic properties, using a single head to perform the measurement.

Topics: quality control, weld camera, weld inspection, Laser welding, image processing, High Dynamic Range, Tube and Pipe welding, laser-based monitoring, Pipe Cladding, welding defect, freeze line

Monitoring Tube and Pipe Production to Detect BEAD ROLL

Posted by Cornelius Sawatzky on Tuesday, May 13, 2014 @ 02:29 PM

Recent advancements in machine vision technology have made a new type of inspection able to see defects related to the forming and welding area of a tube or pipe.  The result is improved quality assurance and process control on the production line.  The new type of inspection device is a laser-based triangulation system that measures the outside contour of a tube or pipe in the vicinity of its weld. 

Typically NDT systems are placed at the end of a production as a final check.  However, the laser inspection system can be placed directly after the weld box.  This system can let operators know what is changing in their welding process, allowing them to perform corrective action before significant scrap occurs. This capacity is especially helpful for one of the most common defects found across all types of Tube manufacturing:  excessive Bead Roll. 

 

The Bead Roll Measurement

The nature of some welding processes such as Laser Beam Welding (LBW) or GTAW (TIG) require that the weld bead remains within narrow range around the centerline of the tube to ensure the best quality weld.  Any small deviation from the centerline can cause a variety of welding defects mentioned earlier in this blog.  With such precision welding processes, the bead position cannot change even momentarily or a bad weld will result.  Bead roll could indicate setup problems in a mill where there are uneven forces on the tube that causes a gradual twisting.  Often, this is avoided by placing the weld box as close as possible to the forming rollers.  However, if a roll still exists in the tube beyond the weld box, the tube may be later rejected as downstream processes will not be able to process a twisted tube properly. In extreme cases, it could cause problems with bead removal later down the mill.

The Bead Roll angle is measured based on the midpoint between the left edge and right edge of the bead width.  The difference between the midpoint position and a vertical axis through the center of the tube defines the angle of the bead roll.  The actual angle also relies on using the ideal diameter of the parent material for calculation. 

May 13.14 Blog Bead roll resized 600 

The Bead Roll Measurement, where “θ” = the measured angle.

 

How the WI2000p System Measures the Bead Roll

Xiris Automation Inc. has developed a non-destructive inspection system called the WI2000p Weld Inspection System. The WI2000p  includes  a laser line and a camera whose optical axis is offset to the axis of the laser line by an “offset angle”.  The WI2000p creates a visible cross-section of the tube by projecting the laser line on to the tube and capturing an image of the line using the camera. The resulting image shows a  profile of the tube surface as if it were cut in cross section.  If a tube is ideally round, the laser image will represent a section of an ellipse and any anomaly such as a bead roll can be mathematically detected. 

The WI2000p bases all of its measurements on the differences between the actual laser profile line seen by the camera, and the ideal mathematical profile based on the tube parameters.  By knowing the position of the actual laser profile, the ideal profile, and the size of the pixels in the image, the WI2000p can detect subtle bead rolling that often escape detection by other quality tools such as Eddy Current testing, or Ultrasonic Testing techniques.

 

Conclusion

A new technique for detecting bead roll on welded Tube and Pipe has been developed by Xiris and is known as the WI2000p weld inspection system.  The WI2000p system is a laser based inspection system that is capable of detecting bead roll immediately after welding to alert the operator of a defect in time to minimize rejects.  The result is improved quality, fewer field defects and a more reliable method for the operator to optimize the welding process.

Topics: quality control, weld camera, weld inspection, Laser welding, image processing, High Dynamic Range, Tube and Pipe welding, laser-based monitoring, Pipe Cladding, welding defect, bead roll

Latest Posts

Follow Me