The Xiris Blog

Blob Analysis Tool for Weld Monitoring

Posted by Cameron Serles on Tuesday, February 02, 2016 @ 06:00 AM

 

  Image Processing is slowly making its way into the welding world.  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 BlobAnalyzer tool from Xiris is a powerful Blob Analysis tool that can measure a variety of properties of objects within a region of interest.  Data can be generated from the properties and then monitored or analyzed so that objects measured or sorted based on their shape parameters.  The net result is a new way for fabricators to enhance the monitoring and controlling their weld processes.


BlobAnalyzer.png

The Blob Analysis tool includes properties such as:

 Area                 Centroid           Perimeter         FormFactor        BoundingBox

 Orientation         Eccentricity      EulerNumber    Hole Count        TouchesBorder

 FeretDiameter    GrayMass        GrayMean        Compactness

Conclusion

  By incorporating image processing tools such as Blob Analysis 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 features in an image, such as the weld arc, 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 can help monitor your weld processes, visit Xiris.com 

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Topics: weld camera, Laser welding, High Dynamic Range, weld monitoring, Laser cutting

Off Axis Mounting of a Weld Camera onto Laser Processes

Posted by Cameron Serles on Tuesday, January 19, 2016 @ 02:04 PM

Off Axis Mounting of a Weld Camera onto Laser Processes

A High Dynamic Range Weld Camera can provide great benefit to a laser welding or cutting process by being able to see the melt pool and seam while the laser is on.  In this blog we explore an additional method of mounting cameras to the laser welding or cutting process – Off Axis mounting of the camera.

 Off Axis mounting of Weld Camera

Off Axis mounting of a weld camera is when the camera is mounted separately from the laser beam delivery head in such a way that it is aimed at the work surface where the laser makes contact.  It contains completely separate optics and lighting components with its own mounting mechanism.  Because of the flexibility of location, a camera that is mounted off-axis can be placed at any position around the laser head to get the best image.  These locations can be categorized as:

  1. Forward looking: to see the seam and work environment prior to the weld;
  2. Backward looking: to see the weld pool and weld bead after welding; or
  3. Sideways looking: to gain an overall perspective of the weld environment.

Co-axial_image_1.png

Off Axis Camera Mounting Relative to Laser Beam Delivery System

 In the above image, a simple laser beam delivery system is shown with a camera mounted obliquely to the laser beam optics.  This provides the ultimate in mounting flexibility to get the best possible image desired.  There are a number of advantages and disadvantages of this type of set up:

 Advantages:

  • More mounting options as to where and how to place the camera relative to the laser head, with various optical configurations and fields of view possible;
  • Extra lighting can be added to see additional background detail that is farther away from laser source and not illuminated by the laser itself.

 Disadvantages:

  • A separate, sometimes complex mounting system is required that needs to be mechanically coupled to the laser head so that both units travel in tandem without relative movement.
  • As most laser beam delivery systems are much larger than the beam spot, the camera has restricted access to be able to view the immediate area around laser spot, making obtaining a good image challenging in some situations.

  Summary

Weld Cameras can be integrated into laser welding and cutting machines using an Off Axis mounting technique.  Such a technique provides the ultimate in flexibility to acquire different types of images as required by the machine designer, yet not be constrained by the optics in the laser beam delivery system.

For more information on how Xiris Weld Cameras can help monitor your weld processes, visit Xiris.com 

Sign up to receive our Weld Video of the Month

Topics: quality control, weld camera, Laser welding, High Dynamic Range, productivity, Laser cutting

Coaxial Mounting of a Weld Camera onto Laser Processes

Posted by Cameron Serles on Tuesday, January 05, 2016 @ 02:30 PM

Coaxial Mounting of a Weld Camera onto Laser Processes

A High Dynamic Range Weld Camera can provide great benefit to a laser welding or cutting process by allowing examination of the melt pool and seam while the laser is on.  In this blog we explore one method of mounting cameras to the laser welding or cutting process:  Coaxial or On-axis mounting of the camera.

In coaxial mounting, the camera is mounted parallel to, and pointing in the same direction, as the laser source.  The image delivery optics for the camera are combined with the laser beam delivery optics via a beam splitter so that the camera shares part of the final optical path through which the laser beam travels.

 A depiction of an On-axis camera mount configuration is presented below.  In this configuration, the camera has the straight through optics while the laser beam is coming in from the side via a beam splitter.

Camera_picture.png

On-axis camera mounted to laser beam delivery system

 There are both advantages and disadvantages to this type of camera set up on the laser process.

 Advantages:

  • Results in a small form factor package that can be tightly integrated into the laser optics head.
  • Operator is able to see the weld in real time because the actual laser optics are used.
  • Camera lighting can be tightly controlled inside the laser optics, minimizing external influences.
  • Operator is able to monitor the work environment pre-weld for alignment; in real time during welding for laser beam monitoring; and post weld to ensure the quality of the weld.

 Disadvantages:

  • Resulting image quality is dependent on the design of the optics contained in the image delivery system. In certain situations, an additional light may be required to illuminate the work piece in such a way as to make it visible through the image delivery optics (see drawing above).
  • There may be coatings or filters on some of the optical components in the laser beam delivery system that inhibit specific wavelengths of light from travelling up the image delivery optics. This may reduce the visibility of some of the darker background areas around the laser.
  • Reflections may appear in the image due to any misalignment in the image delivery system.
  • Because the camera’s optical path is the same as that followed by the laser beam delivery, there is a limited field of view which may not allow the camera to see all of the features of interest.

 Summary

Weld Cameras can be integrated into laser welding and cutting machines using a coaxial or on-axis approach where the camera uses the same optics as used by the laser.  Such an approach provides a physically compact solution but the visible field may be limited by the optics in the beam delivery system.

For more information on how Xiris Weld Cameras can help monitor your weld processes, visit Xiris.com 

Sign up to receive our Weld Video of the Month

Topics: weld camera, Laser welding, High Dynamic Range, productivity, Laser cutting

Integrating a Weld Camera into Laser Welding Processes

Posted by Cameron Serles on Friday, December 04, 2015 @ 01:20 PM

 Integrating a Weld Camera to Laser Welding Processes

 High powered industrial lasers have been incorporated in a variety of metal fabrication processes, most commonly for welding and cutting applications, where the high power of the laser allows for rapid processing speeds.  As fabricators have adopted industrial lasers throughout their shop floor, it has become painfully obvious to the fabricators that the material being processed by lasers had to be prepared and aligned differently than traditional processes.  Because a laser beam is so small, precise fit up and alignment of the material being processed is needed to ensure the laser process is viable.  Careful monitoring of the fit up and alignment is required to ensure a good welding process.  Because of the safety issues of being around a laser light, the only practical way to monitor how the material has been prepared and aligned to the laser head was to use a camera that was integrated to the laser beam delivery system. 

 The laser beam delivery system

The laser beam on most cutting and welding systems is delivered to the work piece using a series of optical components such as lenses, filters and mirrors.  Together the assembly is known as the “laser beam delivery system” and can be complex in shape and size to suit the application, as the laser may have to be bent to be as compact and functional as possible.  Most laser beam delivery systems have a camera port integrated into the assembly to allow a camera to view down the same optical path as that travelled by the laser beam.  By adding a camera to the beam delivery system, the operator can monitor the workpiece material to ensure it was properly prepared and aligned prior to powering up the laser.picture_3.png 

A Simplified Laser Bead Delivery System

 

The Problem

Once the idea of putting a camera on the laser system has been accepted, there is often frustration with the fact that the cameras most commonly used become useless once the laser is turned on.  Because the laser generates enormous amounts of focused light that partially bounces up to the camera or creates very bright keyholes and weld puddles once it hits the work piece, the resulting image is just too bright for standard cameras to see any detail in the brightest sections of the image.  As a standard camera can see about 48-60 dB of range of brightness, it will simply saturate where the image gets too bright, resulting in a white blob on the screen.  The solution implemented by many fabricators and equipment builders?  Turn off the camera when the laser is powered.

 A Better Solution

However, a better solution does exist.  A high dynamic range weld camera can be used in place of a standard camera to adapt to the laser process.  A good weld camera can see more than 140 dB of range of brightness, or a ratio in excess of 10,000,000:1 of the brightest to darkest pixels in an image.  This allows for detail in the brightest area of the image of a laser weld or cut to be seen without saturation while still seeing detail of the background around the weld, including the weld pool or seam.

 By implementing a weld camera to see the laser process, an operator can see what is going on with their laser welding process once the laser power is on, ensuring that the laser beam is functioning correctly: that the beam is focused properly, that the keyhole is of the correct shape (round vs. oval), size and location (relative to the weld seam), and that the weld pool is symmetric on either side of the weld seam and sized correctly.

 Picture_1.png

Image from a High Dynamic Range Camera of a 3000 W Laser

 

For more information on how Xiris Weld Cameras can help monitor your weld processes, visit Xiris.com 

Sign up to receive our Weld Video of the Month

Topics: remote monitoring, weld camera, Laser welding, High Dynamic Range, productivity

Using a View Camera to Monitor Automotive Body Laser Welds

Posted by Cameron Serles on Friday, January 09, 2015 @ 09:29 AM

During the initial stages of automotive assembly, a car’s chassis is built up by welding together all its major sheet metal components, such as side walls, doors, door frames, roof joints, floor panels, the engine cavity and hood parts. The assembly process stage of welding all these components together is known as “body-in-white” and has been the source of much technology advancement in recent years.

One major technology advancement has been the introduction of laser welding processes to replace the traditional methods of fastening and joining the metal components. Laser welding offers numerous advantages over traditional techniques such as resistive spot welding but like any new technology, it requires more precise material preparation and careful process implementation.

 

Essential Advantages of using Laser Welding for Body in White

  • Single-sided access to the point of welding, allowing for simpler chassis design in some situations.
  • Better looking joints that are almost invisible are possible with some creative laser weld placement or by using laser brazing technology.
  • The flanges required to hold together sheet metal components around apertures such as door openings can be smaller, leading to weight reduction and better automotive designs.
  • Higher process speeds that can improve productivity, reduce cycle time, and reduce production floor space

 

However, there are disadvantages of the process….

  • Tight Tolerances. The narrowly focused laser beam requires very precise seam preparation to ensure a successful result. Overlooking this in early automotive laser history resulted in many failures.
  • Specific Repair Methods. Because laser welding is a relatively new joining method, repair techniques specifically designed for laser welding must be used when repairing laser welded joints.

 

The Solution

The solution to this problem is very precise seam preparation (with almost no gap) and precise clamping methods. But even with the best preparation, the seam can vary enough to cause problems with the weld process. With such a process, it is important to maintain very good alignment of the seam to the laser spot: because the laser beam is so small, a small movement of the seam out of alignment may jeopardize the quality of the alignment.

To solve this problem, a high dynamic range camera can be added to the laser process, either coaxially in the optics of the laser beam delivery system itself, or off axis. In either case, the camera can be positioned to see the laser keyhole, weld pool and weld seam. Because the high dynamic camera can see much more of the bright areas, including the weld pool and keyhole, as well as the darker areas such as the seam and background, it becomes much easier for operators to monitor the laser process to verify that it is in alignment.

Another “solution” involves the combination of laser welding and an open arc welding process (e.g. MIG or TIG) in a so-called hybrid process. For such a process, the open arc welding method delivers extra weld material that makes sure that the seam flanges are processed even without a precise seam; the laser permits deep penetration into the substrate, and the welding speed is significantly higher than if an open arc welding process was used on its own. Once again, the use of a High Dynamic Camera can help verify that all components of the weld environment are working correctly, in particular the alignment of the laser arc to the seam.

 

Jan_9.15_Blog_Body_in_White

Figure 1: Camera Running Co-Axially to the Laser Beam Delivery System1

 

Conclusion

Laser processing continues to grow market share in a number of applications in body-in-white automotive manufacturing. However, as with any new process, it must be carefully implemented to take full advantage of the technology. To maximize the chances of success, a Weld Camera with a High Dynamic Range imaging capability should be used to provide operators with adequate weld visibility to monitor and control the laser to seam alignment before it moves out of control and causes defects in the welded seam.

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1. Adapted from: A. Ribolla et al. / Journal of Materials Processing Technology 164–165 (2005) 1120–1127

Topics: Laser welding, welding automation, High Dynamic Range

How to Get the Best View of an Open Arc Weld

Posted by Cameron Serles on Thursday, July 17, 2014 @ 06:00 PM

Attaining a good image of a weld and the surrounding background has been a struggle ever since video cameras for welding became available.  The problem has always been the range of brightness that occurs during welding: the ratio between the maximum and minimum light intensity is usually too great for a standard camera to measure properly.  Standard cameras on the market today can typically measure about 1,000 levels of brightness between the maximum and minimum light levels in an image.  However, in a typical open arc welding environment, there is a brightness range that can exceed 10,000,000 levels of brightness between the brightest portion of the welding arc, and the darker areas surrounding the weld.  Using a standard camera to image such a weld will create an image similar to the image below on the left, where the camera sensor will image the scene up to a point and then saturate when it gets too bright. This causes the bright areas of the image to appear as a white blur.

 

To solve this problem, Xiris Automation has developed the XVC-O View Camera that uses advanced electronics with logarithmic sensitivity to be able to see more than 10,000,000 levels of brightness in an image.  As a result, more image detail is visible than ever seen before. The detail of the weld arc, the shielding gas, weld pool, torch tip, and weld seam can all clearly be seen.  The image below on the right is an image taken from the XVC-O camera of an open arc welding process. The weld arc is no longer saturated and is clearly visible as is the detail of the background, providing better quality information for the weld operator.

 

GOOOOOOD resized 600       Standard Camera Image of a Weld                      Xiris XVC-O Camera Image of a Weld

With the ability to see more detail of the weld arc and the surrounding environment, welding technicians are able to use the XVC-O to better control their welding processes through better quality assurance and process feedback. 

To see examples of the video quality possible with the XVC-O across a variety of welding processes and materials, please see our Weld Video Library here.

 

Topics: weld camera, weld inspection, Laser welding, welding automation, weld environment, Machine Vision, image processing, Education, Welding Process, weld video, Xiris, image contrast

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