ABB robot promises precise laser welding for chemical vessel production

The end user was keen to solve logistical challenges by bringing the welding of the product in house from a European sub-contractor. As well as offering more control over the process, reshoring production would avoid the need to deliver raw materials to the sub-contractor and ship back the finished product.

Laser welding offers the high accuracy required in producing this type of process vessel. It gives better quality welds ensuring that the weld maintains high integrity and prevents any distortion that can result from the higher heat dispersion of other methods. It also offers faster throughput.

Because laser welding presents a risk of eye injury to human workers, a fully enclosed automated solution was required.

Cyan Tec Systems was asked to develop the solution. The company, an ABB Value Provider, has extensive experience designing and building robotic automation solutions for companies in industries including aerospace, automotive and nuclear.

The system required a machine that could carry out the immediate task required but which also had the flexibility to handle different welding tasks in the future. For this reason, Cyan Tec chose a robot solution rather than a gantry design. Although a gantry would have met the immediate requirements of the tasks, it would not offer the longer-term future proofing that the customer specified.

As the customer already had an ABB robot on its shopfloor, Cyan Tec looked at ABB robots that could fulfil the brief. This would ensure that the customer’s engineers could conduct basic programming tasks without having to learn a new language.

ABB could supply a versatile six axis robot but could also provide a track that the robot could run on. Fitting the robot to an ABB IRBT motion system effectively gave it a seventh axis, allowing it to run down the length of the component to produce an accurate weld. The version suitable for the IRB 6700 can provide a travel length of up to 19.7 meters in one-meter steps. With a simple design, the track solution offers best in class path accuracy and a position-to-position time of less than 3.4 seconds for a four-meter length.

With a reach of over three meters and running on the track, the ABB IRB 6700 robot can weld accurately along the two-meter length of the component. The robot has a higher payload than that required for the application, but this also gives the flexibility to carry a heavier welding head or other effectors if requirements should change in the future.

The solution also incorporated a vision system on the laser head, allowing it to compensate in the event of misaligned component elements.

Cyan Tec used ABB’s RobotStudio simulation software to prove the layout and operation of the solution. Simulating the application, complete with a graphical animation of the robot’s operation and its interaction with the other solution elements, reassured the customer that Cyan Tec had chosen the correct robot with the right reach. It also proved that it would not foul other objects or collide with any of the ancillary machinery.

RobotStudio also eliminated much of the risk involved in developing the application, as it avoids the need to reengineer the project if problems are discovered during the commissioning stage.

Because a Class 1 laser was used, which could potentially cause damage to eyesight if users are not wearing suitable eye protection, the robot needed to be in a laser proof enclosure. Cyan Tec designed a system that allows the customer to load one component for welding while unloading a finished component, speeding up the rate of production.

The enclosure incorporates two sets of welding fixtures, one for welding together two flat sheets into one. This is then unloaded, sent to a pressing section for formation into components and then reloaded into the enclosure on the other set of fixtures for final welding into the complete product. This final welding stage takes around two minutes for a completed product.

As well as the robot, track and enclosure, Cyan Tec integrated the laser source and ancillary components such as the tooling, laser chiller, fume extraction system and assist gas control.

Richard Copson of Cyan Tec says: “Over the last six to seven years, we have done a lot of laser applications for welding and cutting. Many of these have used ABB robots and we have built up a bank of experience and expertise, so familiarity with the solution was a big influencer in choosing a robot for the customer.

“The experience we have with ABB robots means we don’t always need their help to design and develop a solution, but they are always on hand if we need to use different features or do things we haven’t done before. As an ABB Value Provider, it’s good to know that their support is always available if we need it.”