May 11, 2011
Automated Welding Improves Safety and Productivity in Nuclear Industry
Following the introduction of its new DLS range of 3D digital laser scanners, Oxfordshire-based Meta Vision Systems has put together a VistaWeld package designed specifically to automate welding jobs in the nuclear industry. These are characterised by multiple passes of the weld torch to fill deep, narrow grooves down to 8 mm across between plates up to 300 mm thick, mainly of highly reflective stainless steel.
The company claims that this is the first time full automation has been made available for such applications, which until now have been carried out by an operator watching a camera image of the seam and using a joystick to position the weld torch manually. This is significantly slower and with up to 50 weld passes needed for the root, hot, fill and cap phases, there is risk of human error, with consequent safety and cost implications.
Factors that complicate the welding process are a need for the sensor to see from top to bottom of the groove and to illuminate the sides to ensure positional accuracy, even though the walls can be angled at one degree (i.e. are nearly vertical). Another requirement is to preheat the plate to around 300 degrees Centigrade, ensuring that there is sufficient heat to fuse the material but not enough to cause cracking and compromise structural integrity.
The VistaWeld / DLS seam searching and joint tracking system is typically used for submerged arc welding of butt, V, and U joints. It not only tracks the seam and positions the weld electrode accurately and automatically, but additionally can record position correction data for each pass to provide certification of the manufacturing process. This is an important feature for the nuclear industry, as traceability is mandatory in the event of failure.
In fully automatic, multi-pass control mode, during the first pass of each layer, the system measures the joint width at that depth and determines the number of passes required for the layer. During the last pass of each layer, the system measures the remaining depth and determines whether to continue with filling or go to capping. Advanced adaptive fill to compensate for joint area variations by controlling welding parameters directly to adjust the deposition rate at each point on the joint is available as an option.
Alternatively, in semi-automatic mode, the operator manually selects the type (root, hot, fill or cap) and position (left, right or centre) of the next pass.
Digital laser scanner is unaffected by reflections
The DLS scanning-spot laser sensor has proved to be ideal for this application. It uses a 2048 element, linear CCD (charge coupled device) and has much of the signal processing integrated inside the sensor head itself. Compressed air cooling is provided to keep the unit within its operating temperature range.
Conventional laser vision systems based on triangulation use a laser stripe projected onto the target. As constant laser power is used, it not possible to vary the intensity along the stripe to increase the light reflected from dark areas and decrease the light received from lighter areas. The camera images the complete scene including either side of the stripe, which can lead to further problems with dynamic range and unwanted reflections.
In contrast, Meta’s DLS sensor is based on a scanning spot rather than a stripe, solving the two main problems of stripe-based triangulation when dealing with shiny materials like stainless steel. First, it is easy to implement effective automatic gain control to compensate for variations in workpiece reflectivity along the length of the stripe. Second, imaging is via the CCD, which only looks at the region of interest and is not affected by reflections.
Additional benefits of the scanning technology include a programmable field of view and independence of the sensor’s depth of field from its width of field, providing high quality in both axes simultaneously. Moreover, at the touch of a button, the sensor can project the spot to measure and control standoff – the height of the end of the electrode from the weld – and to assist manual horizontal tracking.
This is normal procedure when capping. The horizontal position is obtained either from path memorisation in the case of a longitudinal welding operation, or by tracking a line scribed at the same time as the root pass weld is laid down in case of circumferential welding. Fully automatic capping with memory replay is, however, also possible.
Overall, the use of VistaWeld / DLS provides numerous benefits including higher weld speeds, better quality irrespective of operator attention level, superior interpenetration of the weld zones, reduced scrap and rework, and lower manning levels. Meta has supplied over 2,700 laser seam tracking systems worldwide.
Release no: 1039(GN)
February 17, 2011
Laser Seam Tracking Raises Quality and Productivity in Robotic Welding of Vehicle Exhausts
British-manufactured laser seam tracking sensors from Meta Vision Systems are increasing the efficiency of automated welding cells producing exhaust treatment products for heavy vehicles at the Nyköping factory of Swenox AB, Sweden.
European legislation on exhaust emissions is becoming increasingly stringent, which has prompted advanced on-vehicle treatment solutions to be developed by companies like Swenox to meet the requirements of lorry and bus manufacturers.
The products catalytically convert carbon monoxide, unburnt hydrocarbons and oxides of nitrogen to their harmless gaseous constituents and water vapour, and include filters to trap particulates. They are integrated into complete exhaust systems that Swenox also fabricates to customer requirements.
Design and manufacture of such system are extremely demanding, requiring gas tight joints on convoluted shapes. There are often conflicting criteria, such as a requirement to minimise weight while maintaining durability and operational reliability.
A considerable amount of arc welding is needed to join the individual components. The nature of the constituent materials results in spring back and heat distortion, making automatic welding difficult to achieve and so calling for the use of seam tracking. However, due to the large variation in reflectivity of the materials, most ordinary laser sensors struggle to detect the seams.
Oxford-based Meta Vision Systems' new SLS sensor, which forms part of its SmartLaserPilot system, has overcome the problem through its singular ability to remain unaffected by varying surface conditions and reflections from the metals being welded. It does this using real-time, automatic intensity control of the laser stripe, allowing the vision analysis software to deliver a high quality image at all times.
The Meta sensors are used in two twin-robot welding cells at Swenox, a single robot controller driving both ABB robots in each cell. The sensor head contains a megapixel camera and more computing power than a powerful laptop computer. With its weaving, seam search and reframing functions, it collects information on the position of the joint being welded and communicates it to the robot controller via an Ethernet link and switches.
Based on this data, robot motions are continuously adjusted when effecting multi-layer lap joints with tacks as well as circumferential and other welds. The welding equipment was supplied by Fronius CMT.
Glyn Powell, the engineer responsible for the robotic cells at Nyköping, commented, "Installation of the Meta SLS vision system has been a major success for Swenox.
"To be able to assemble and tack-weld components off-line and then move them into our robotic cells and weld them with consistent quality without any modification to the programs is a massive achievement.
"Our aim is to manufacture a top quality product that is the very best of its type available on the market today and without doubt the Meta laser tracking system is playing a major part in our achieving this goal."
Release no: 1042(CS)
January 21, 2011
New Laser Guidance System for Automated Welding in Longitudinal Pipe Mills
Meta Vision Systems (Oxford, UK and Montreal, Canada), the world's leading supplier of optical seam tracking systems for tube and pipe mills, announces a new version of its market-leading VistaWeld system aimed specifically at increasing the speed and accuracy of submerged arc welding (SAW) in longitudinal pipe mills.
Based on a review of typical longitudinal SAW mill operations involving tack and OD (Outside Diameter) welding, the new system addresses some well-known issues. In particular, the latest VistaWeld includes accurate, non-contact tracking of the true root position and built-in look-ahead compensation as standard features.
The system harnesses the power of Meta’s recently introduced Smart Laser Sensor (SLS) technology. It integrates a high resolution, high performance SLS sensor head within an updated VistaWeld architecture based on an Ethernet backbone and Meta’s new, flexible Ethernet IO board. The combination has made it feasible to include the desired features while reducing system complexity and improving ease of use.
TruRoot tracking finds the actual root of the joint for OD SAW, even though the root may be covered by the tack weld. The software uses the higher resolution and quality of the SLS sensor, together with image analysis algorithms from Meta’s well known multipass welding system, to detect the edges of the tack weld in the bottom of the joint.
From this and the overall joint profile, the true root position can be computed. Tracking the actual root derived in this way improves penetration for the OD weld itself while also improving ID/OD weld interpenetration.
OD SAW on longitudinal pipe mills typically uses a multi torch configuration with as many as five or six individual wires welding in one pool. The weld head is therefore large, taking into account the number of torches and need for flux delivery and recovery.
As a result, the laser sensor has to be positioned a relatively large distance in front of the weld area. This so-called look-ahead distance can be 250 mm or more. Depending on the shape of the pipe, tracking inaccuracies can result if simple algorithms are used.
The standard tracking feature within the new VistaWeld uses the look-ahead distance, welding speed and other information to determine the correct position for the welding head at all points along the pipe. It is particularly beneficial if the pipe forming method has given rise to geometric distortion, as is often the case.
Tests on one series of longitudinal pipes showed that, in some cases, look-ahead tracking was four times more accurate than conventional tracking, significantly enhancing production by improving weld quality and minimising defects.
For example, the superior vertical tracking accuracy maintains the correct stickout (distance from contact tip to work) over the complete length of the pipe, improving weld quality and eliminating weld defects. The improvement in horizontal axis tracking precision combines well with the TruRoot feature to give a double accuracy benefit.
According to Bob Beattie, Meta’s managing director, “We have fifteen years of experience in longitudinal pipe mills, so we were able to identify precisely how to improve our system to give their welding engineers exactly what they wanted.
"We believe that, with the new features, the new VistaWeld system is the best available on the market.”
Release no: 1041(PR)
October 20, 2010
New, Smart Laser Probe for Automated Welding Machines
Meta Vision Systems has launched a new laser seam tracking system that applies the company’s latest sensor technology to welding machine applications. Called Smart Laser Probe, it is manufactured at the company's Oxfordshire factory and will be demonstrated on the Meta stand at the forthcoming Fabtech exhibition in Atlanta, Georgia, 2nd - 4th November 2010.
The concept of Meta’s original laser probe was to provide laser seam tracking performance and reliability at a price roughly comparable with mechanical, tactile probe tracking. The system has proved successful in applications such as tank welding, railway wagon production, fabrication in shipyards and other automated welding operations involving simple linear, rotary or circumferential operations.
Using the latest advances in megapixel CMOS cameras, embedded electronics and high resolution displays, Meta has designed the new generation of Smart Laser Probe with significant improvements in performance, reliability and ease of use, while maintaining its competitive price.
The non-contact, seam-tracking system senses and compensates for any deviation from the nominal weld path to ensure highly accurate, automated welding, without the need for expensive fixturing or manual guidance.
Meta's SLS (smart laser sensor) technology incorporates the image processing hardware and software inside the sensor head. This greatly simplifies the architecture of the system, which uses an Ethernet backbone to communicate between the sensor head, colour touch screen display and integrated multi-function I/O board. Advanced anti reflection techniques have been incorporated in both the hardware and software, so system performance with more reflective metals such as aluminium and stainless steel is substantially improved.
Even though the electronics for image processing is now in the sensor head rather than a separate controller, as previously, a high sampling rate of 30 full frames per second at megapixel camera resolution underpins fast welding speeds and better accuracy. Additionally, partial frames can be analysed at substantially higher rates.
A further advantage of the new design is that it can tolerate a wide
Ease of use has been improved by the inclusion of a controller with a colour touch screen instead of a simple monochrome video monitor. The touch screen is used for monitoring welding performance at a glance and for diagnosing any maintenance issues during operation. Multifunction I/O within the cabinet allows easy interface to a wide range of equipment.
The operator pendant has been completely redesigned to be more robust and informative. It includes multi-colour LEDs to give the operator status feedback directly from the pendant itself.
November 27, 2009
New Digital Laser Scanner Speeds Welding of Wind Towers
New Digital Laser Scanner Speeds Welding of Wind Towers
New Generation Laser Sensor Increases Quality & Speed of Welding
A new laser sensor has been launched by British manufacturer, Meta Vision Systems, for all types of mechanised and robotic welding. It is the first such sensor to incorporate high performance image processing in the sensor head itself, rather than needing a separate computer, and has many applications throughout manufacturing industry.
The thickness of the steel plates that form the base of a wind tower can be 50 mm or more, while the middle section is fabricated from lighter gauge metal and near the top, the steel is thinner still. Welding of these various gauges requires different procedures. The base is typically prepared with a U joint profile and welding takes place in several passes. The middle section requires a V type joint and is welded in one or two passes. Steel at the top is welded with a simple butt joint preparation. The DLS200 sensor has a fully programmable scan configuration, which means that a wide scan can be used for the U and V joints, but a narrow scan with high resolution can be used for the smaller butt joints.
META CELEBRATES 30th ANNIVERSARY AT TUBE 2014
Meta Vision Systems, the leading UK manufacturer of laser guidance systems for automating arc welding, celebrates thirty years of Welding with Vision at the TUBE 2014 exhibition. Meta was a spin-out from Oxford University in 1984, following a successful research project to develop a laser vision system for real-time control of robot welding.
The international show, featuring machinery and accessories for manufacturing and processing of tubes and pipes, will take place in Düsseldorf from 7th – 11th April. Meta will take its largest stand ever, 6B39, and will stage several live demonstrations of new products being launched.
In addition to remaining active in robot welding, the firm has developed considerable expertise in many different tube and pipe applications over the past thirty years and is now generally considered to be one of the leading suppliers of vision and control systems for the tube and pipe industry worldwide.
Within an overall theme of applied innovation, Meta’s stand will show a completely new pipe measurement system. With increasing demands for traceable measurement data from pipe buyers, the manufacturer has harnessed its proven experience in pipe bevel measurement and pipe inspection to develop a suite of new pipe measurement products. They represent a major expansion in the company’s activity in the sector and will be on show for the first time in Düsseldorf.
Meta’s recent developments in longitudinal pipe mills will be highlighted in partnership with Hyundai RB, which has built a new longitudinal pipe mill in Ulsan, Korea, using Meta systems at every stage of the pipe welding process. They are used to control tack welding, ID welding, OD weld joint milling and OD welding. The result is a pipe mill with advanced automation throughout, combining excellent productivity and high quality.
In the spiral pipe sector, Meta will be premiering a new video giving an in depth review of Meta’s new spiral mill control system. This includes mill control, welding control, laser vision and video monitoring, all within a single integrated and networked control system. As a result of Meta’s attention to detail during the design phase, the latest mill control installation was quick and painless for all concerned, enabling the mill operator to start making high quality production pipes in a shorter time than ever before.
Meta looks forward to welcoming its many tube and pipe customers from all over the world to its stand and showing them the latest developments.
Meta Leads the Way in Friction Stir WeldingLaser tracking equipment manufactured by Meta Vision Systems is being integrated into the latest generation of friction stir welding (FSW) machines built by PTG Heavy Industries at its Elland factory in West Yorkshire. As a result, the internationally successful Powerstir FSW machine range may now be controlled automatically without the need for accurate fixtures.
Several Powerstir machines have already been delivered with Meta's Smart Laser Pilot (SLPi) weld joint tracking system, including to customers in Europe and China.
The work that Meta is doing in this high technology field has led to the firm researching and developing novel applications of FSW under the current EU Framework 7 programme.
FSW was invented and patented by TWI (The Welding Institute) in the UK in 1991 and was adopted by PTG in the development of its world-beating Powerstir machines. Meta, another British company, based in Eynsham, Oxfordshire, has now added its expertise to help automate the process and simplify machine operation.
Being a solid state process, FSW overcomes many of the problems associated with the melting and resolidification of traditional arc welding. A rotating tool is moved along the line of a butt or lap joint, generating frictional heat that softens the material of the parts being joined. Together with carefully controlled clamping, the result is high strength, defect free welding.
Meta's SLPi, which uses the company's high resolution Smart Laser Sensor (SLS), detects the line of the weld joint so that the rotating tool moves exactly along the correct path. With a combination of a mega-pixel camera, high quality uniform laser stripe and special optical and electronics designs, the SLS gives a very high quality joint profile from which the seam position can be extracted reliably. The tool is therefore able to be guided accurately along the line of the joint.
Jonathan Moore, Meta’s Technical Director, commented: “We have supplied tracking and control systems for almost every type of welding and are particularly excited to be involved in FSW and helping PTG with its successful export drive.
"FSW shows great promise in aerospace, shipbuilding and other important sectors. Our involvement with the EU R&D programme is an indication of our commitment to extend our knowledge of this important manufacturing process and further its commercialisation."
Release no: 1045(CS)
Meta Gets Wind of a Big Order in China
Oxfordshire-based vision system manufacturer, Meta Vision Systems, has received an order from a large Chinese windtower manufacturer for 14 of its DLS digital laser scanners. They will be used to automate welding operations during production of monopiles for offshore wind installations.
Meta’s DLS is unique among laser vision sensors for welding in that it uses the scanning spot principle rather than the more usual laser stripe method. The scanning spot system has significant advantages when welding the deep joints that are common when manufacturing monopoles, where wall thickness can be over 100 mm.
Dr Jing Zhao, Meta’s Country Manager for China, commented: “We are very happy to have won this contract against tough competition and following a direct comparative evaluation in the customer’s factory.
"The performance of the DLS in generating accurate profiles of deep, narrow weld joints is a significant benefit for our customers. The large depth of the joints results in extended welding times, so continuous, consistent performance over long periods is vital.
"Monopile welding has to be done quickly and efficiently to meet production targets but, at the same time, high quality standards are demanded. This project demonstrates that the quality and productivity benefits of advanced welding automation are persuasive, even in situations where cost considerations are very important.
"Thanks to our emphases on quality and customer satisfaction, the Meta brand is well established and highly respected in China. This important new project gives us an opportunity to reinforce our leadership position in the market there.”
The windtower industry worldwide has become extremely competitive with the evolution of designs that place increasing requirements on fabrication and welding. To be competitive, it is necessary for windtower manufacturers to combine high productivity with excellent quality by using the best practices available.
Meta has extensive experience in the field, having been working on windtower and monopile welding for over fifteen years, with a range of installations in the UK, USA, Canada, China, Korea, Netherlands and elsewhere.
Release no: 1046(PR)
Meta Turns Laser Tracking Inside Out
Meta Vision Systems has released a new version of its VistaWeld laser tracking system for controlling the position of the internal welding head on spiral pipe mills.
There are two conventional ways of controlling the position of the weld head inside a pipe. In the first method, the laser sensor is mounted directly to the internal head and controls its position by sensing the joint directly ahead of the point of welding. The disadvantage is that there may not be enough space for the sensor inside pipes of small diameter. Another problem in two-step mills is that the internal environment is severe due to the volume of weld spatter.
This led to the development of the second traditional method in which the sensor is mounted outside the pipe on an additional servo slide. The sensor can track the joint dynamically from the outside, as the weld head inside the pipe is mounted on a similar servo slide which mimics the action of the external slide. The disadvantage of this approach is its high cost and complexity, as it requires an expensive additional servo slide system for the sensor only. Moreover, the machine operator has to synchronise both sensor and weld head slides before welding can begin.
Meta's new method has the advantage of placing the sensor on the outside of the pipe but without the disadvantage of a separate sensor slide. The company has developed a new calibration method which, combined with Meta’s high resolution Smart Laser Sensor (SLS), means that the laser sensor can be mounted in a fixed position on the outside of the pipe yet control the position of the weld head accurately inside the pipe. Since the sensor is fixed, there is no need for a separate sensor slide.
The new inside-out VistaWeld SLS tracking system has already been installed on several spiral mills, with good results. It is applicable equally to one-step and two-step mills.
Bob Beattie, Meta’s MD, commented: “Over the past fifteen years, we have supplied many systems for spiral pipe mill ID welding and have acquired a lot of experience in the application.
"Even though we developed some very small laser sensors for going inside, previously there was always a restriction on minimum pipe diameter, whereas with this new approach there is no limitation.
"Accurate laser tracking is now available for ID welding on pipe of any diameter. What’s more, the sensor provides accurate as-welded mismatch measurement that can be monitored by mill operators or used as the input to an automatic mismatch control system.”
Release no: 1044(PR)