Optimized tool assembling thanks to robot technology

The Waelzholz site in Plettenberg, Germany, specializes in the production of hardened and tempered spring steel strip and fineblankable grades. Slitting the cold rolled steel strip to customers’ individual specifications is an important step in the process. To assemble the necessary tools for these specific orders, Waelzholz has now brought a special robot into operation that was developed using a great deal of the company’s own expertise. The result is greater efficiency, less physical strain on employees, and a precisely defined slitting setup for each item.

The team around Plettenberg-based production and project manager Martin Krämer is justifiably proud of the new blade assembly robot. Its main job is to assemble the tools for the blade shafts¹ on one of the slitting lines in the production site. To do this, the robot has to select the right combination from a stock of 3,000 tools. The clever thing about this is that the robot’s systematic selection of blades, ejector rings, and adjusting rings is based on algorithms incorporated into the control software containing the knowledge of Waelzholz’s specialists regarding the combination of blade condition, quality, and tensile strength of the material being cut. But that’s not all. Martin Krämer explains further special features: “The new robot can not only automatically remove certain tools from one of the three rotating storage towers and assemble a slitting setup from them. The line also includes a control station that monitors the condition of the blades’ cutting edges. Before this takes place, the blades are cleaned of dirt in an inline washer – and all of this happens while the robot is in operation.”  The robot’s extremely precise functionality is also quite impressive, as Martin Krämer explains: “The robot can securely grip tools from a width of only 1 mm (0.039 inch). This requires an extremely high degree of precision.”

In addition to the custom-developed robot technology, the internal team’s smooth collaboration is also worth mentioning. Krämer reports: “We had to coordinate across multiple departments – including electrical and mechanical engineering, production, and purchasing – throughout the entire blade assembly robot project. I would like to thank everyone involved for their hard work and dedication – from early in the morning until late at night, on weekends, and even on holidays – and for their fantastic teamwork.”

“Our requirement for the manufacturer was that the robot should fully automate the entire tool assembly process, including the transfer and retrieval of the slitting setup to and from the rotary table. This includes both the aforementioned edge inspection and the washing of the tools,” sums up Timo Ludwig, who is also a member of the robot project team and is responsible for the mechanical systems at the Plettenberg site. This complete process will increase the efficiency of the slitting line in the future. What employees used to do by hand with the same level of precision is now done by the robot, sometimes faster and with unwavering accuracy. The employees operating the slitting line can now use the time saved productively to achieve a higher tonnage.

The employees also appreciate the ergonomic benefits that the robot offers them, as they no longer have to move the heavy tools by hand, as Ludwig explains: “If tools have to be changed several times during a shift, the weight that has to be moved can add up to more than a metric ton (2,205 lbs) over the course of a day.”

All in all, the new slitting robot represents another important step for Waelzholz in the automation and optimization of its own production processes. But for the technology leader, robots in the cold rolling industry are nothing new – the company already uses robot applications at several of its international locations to increase quality and flexibility.

¹ Blade shaft: cylindrical axle that is equipped with tools (blades, rubber ejectors, spacer rings) in a defined sequence for the respective slitting process. The slitter head consists of two blade shafts, one above the other: a top and a bottom shaft. The material being cut passes between the two rotating blade shafts and is cleanly and precisely cut to the desired final width according to customer specifications.