Arc welding adaptive seam finding system

Arc welding adaptive seam finding systemKeywords: LMI Selcom, Arc welding

A new, improved lower costing arc welding adaptive seam finding system that is said to easily interface with new or existing robot systems and assures production of high quality welds within very narrow mechanical tolerances over long periods of time with a search time of under one second is now available from LMI Selcom in Gothenburg, Sweden.

Lower costing, and described as more user friendly and easier to integrate in the harshest of industrial environments, the new SeamFinder™ 2 system from LMI Selcom reportedly assures optimum welding quality by providing accurate and rapid localization of most seams (Plate 1).

Other benefits claimed of the SeamFinder 2 system include higher quality production, more consistent and quality welds, a reduction in scrap and rework time as well as a reduction in trimming and fixturing requirements.

  Plate 1 LMI Selcom's Seamfinder 2

The system's Class II or optional Class lllb non-contact industrial LMI Selcom SLS (Selcom Laser Sensor) 2301 is compact in design which allows use in small work areas. The sensor's visible laser light is also said to make it easier to program. For optimum quality, measurements are insensitive to ambient light, surface texture or colour changes. Weight of the sensor is 0.8lb (600g).

The SLS 2301 sensor is integrated with an SLS PPU and to most robot systems with standard RS-232 or RS422 interface for maximum flexibility.

Search types the system can accommodate include fillets, butts and edge/overlap joints. Distance measurement can also be given for real time Z height positioning.

Applications are thought to be numerous for aerospace related industries and include robotic arc welding of objects.

Besides robotic arc welding, the system can also be integrated in robotic sealing, cutting and assembly applications. The sensor is also reportedly not affected by normal welding smoke, excessive electromagnetic interference generated by high alternating currents or the nature of the work surface. This is said to allow operation of the system in temperatures ranging from 328°F to 120°F (08°C to 50°C).

"What we are offering the industry is a more cost-efficient, totally integrated user-friendly system that can save a manufacturer time and money by increasing weld quality and shop productivity," noted David Allen, business area manager in North America for the Industrial Sensors Division of LMI Selcom."The new and improved system is ideal for robot manufacturers, systems integrators and OEMs desiring to further improve the consistency and quality of their welds within extremely narrow mechanical tolerances over long periods of time."

Allen noted that the new SeamFinder 11 system replaces the first-generation LMI Selcom seam finding system, which has been installed in more than 600 installations worldwide.

The robust design of the system's LMI Selcom SLS 2301 non-contact industrial laser sensor reportedly allows use in the harshest of industrial environments.

The sensor is enclosed in a NEMA-1 2 (IP50) aluminium housing for optimum air tight sealing and protection from moisture and dirt. A standard cooling, air purge and pneumatic shutter protector further enhances use in harsh industrial areas.

Said to be especially suited for thin sheet resistant welding and plasma arc welding applications with minimum thickness of 0.032in. (0.8mm), the SeamFinder 2 system mounts close to the welding torch of the robot to assure optimal welding quality by accurately and quickly locating seams to be welded.

The system is described as measuring the distance to the work object by optical laser triangulation. The intelligent SLS sensor controller or PPU with its built-in processor and software transforms this signal from the sensor head to calibrated digital data. Once the sensor has located the seam's position, the result is rapidly reported to the robot's controller. The controller then precisely determines the actual position for the welding seam or corrects the robot's welding torch to the joint to be welded. The robot is then said to correct welding parameters quickly and easily adapt to varying gaps and measurements to assure a perfect weld.

With the SeamFinder 2, the robot reportedly always positions the welding tip at the exact spot. Search accuracy of the system with an average robot is stated to be ±0.016in. (0.4mm). Sampling frequency is 16kHz and bandwidth 2kHz. Search time is stated to be under 1.0 second.

Other features claimed of the sensor include a measuring range of 1.02in.(26mm) and resolution of 0.002in. (6.5µm) from a stand-off of 7.1in.(180mm). A dynamic laser feedback loop reportedly allows accurate, virtually error-free measurement with total reliability and repeatability up to 32,000 times a second within a small, defined spot using little power.

Power required is ±18-32 volts DC output can be analog or digital. The dimensions of the sensor are 3.8in. x 4.0in. x 1.0in. (95mm x 101mm x 25mm).

According to LMI the robot can be programmed with such welding dimensions as plate thickness or type of joint. During the search process, one or more points along the joint are defined in two or three dimensions. All searches are accomplished without the arc being actuated.

Further details are available from LMI Selcom. Tel: +46 31 36 25 00; Fax: +46 31 44 61 7 9; E-mail mmailto:martin.sanden@lmint.com;Web site: www.lasersensors.lmint.com