The pillow plate is made by joining two stainless steel plates together in a specific pattern using laser welding or spot welding, and then expanding them under high pressure to form a pillow shape. Hot or cooling media can flow under these pillow plates under pressure. These pillow plates can be used as heat exchangers in various industries, including the food industry, storage tank and equipment manufacturing, and processing systems for various bulk materials.
The equipment required to produce different types of sleeper boards is as diverse as the applications they are used in. Keppels Laser Welding BV, a Dutch company headquartered in Enschede, specializes in a variety of specialized equipment for laser welding sleeper boards. Henk-Jan Keppels, mechanical engineer and owner of KLW BV, said, “From the beginning, we worked with the expert team at Soft-O-Matic to develop automation systems for our equipment. Soft-O-Matic engineers have successfully implemented many projects using the Beckhoff TwinCAT automation platform, and we quickly experienced the advantages and benefits of PC-based control systems.” Rogier van Stapele, software expert and owner of Soft-O-Matic, added, “Laser welding machines require high dynamism and high quality levels, which are precisely the hallmarks of Beckhoff systems.”
Lean controller design, easy to operate
Keppels Laser Welding's pillow plate laser welding machines are sold worldwide and are highly favored by tank and equipment manufacturers. "One of our main goals in the design and manufacture of laser welding equipment is to reduce the number of required parts and suppliers," says Henk-Jan Keppels. He explains that a modular control system that enables efficient machine configuration and modeling is ideal for achieving "small and sophisticated" machine designs.
The Beckhoff CX2040 embedded controller, which can be directly connected to EtherCAT I/O terminal modules, serves as the control platform. The TwinCAT NCI automation software integrates motion control and sequential control functions. "The control platform is very compact and can be installed on a one-meter-long DIN rail inside the control cabinet," said Keppels. "In addition, the EtherCAT AX5805 servo drive with integrated safety technology and the servo motor using single-cable technology constitute a complete motion control solution, which significantly saves space. In the future, we will also consider using EtherCAT P to make our equipment even more compact and further reduce wiring."
“Another important quality criterion for Keppels Laser Welding customers is that the laser welding machine must be easy to operate,” Henk-Jan Keppels continued. “We use a remote CP3919 control panel connected to the CX2040 controller via CP-Link4 as the HMI. We require the HMI to be simple and intuitive. This means that no matter how complex the task, no specialized CNC knowledge is required to operate the equipment.” The HMI screen displays all process data in animated form to prevent operator errors. “When developing the control software, we focused on reducing complexity through independent, simple modules. This gives the software the robustness and manageability required for future development,” Rogier van Stapele explained. “We used UML (Unified Modeling Language) to model and create the software application, generating easily extensible and reusable code. This code can then be designed based on UML in TwinCAT and coded in detail using an existing editor.”
Product definition file initiates the production process.
Unlike many CNC machine tools, Keppels equipment operators do not need to directly use CNC programs. Instead, the production process is guided by a file generated using CAM tools during job preparation. It is based on pre-selected production parameters and customer-provided CAD designs. The file defines the product to be produced, creates a visualization on the HMI, and automatically sets up the machine. In other words, when the start button is pressed, the equipment automatically creates a new CNC program and executes it. Both the product and machine status are taken into account, so if production is interrupted, unfinished products can be processed subsequently. Processing steps can be repeated or omitted according to the operator's requirements. In dual-laser-head welding machines, the current configuration (1 or 2 laser heads, laser head 1 only, or laser head 2 only) is also handled in the CNC program. Another advantage of using product definition files instead of the usual CNC programs is that products can be produced on different batches or different models of equipment without adjustment, because the product definition is equipment-independent.
Online monitoring of process
“Since we started using the CX2040 as our control platform, communicating via Ethernet has enabled us to offer a wide range of additional functions on the laser welding machine,” Henk-Jan Keppels recalled. “Of course, we use EtherCAT as the communication system. The TwinCAT software scans all I/O and monitors all events that occur.” A database application logs all diagnostic and event data provided by the PC control platform. The DataLog can be accessed via an internet connection on the device, so data storage is also fully automated. “With the PC platform, we can monitor and program the device online via a remote service module. For security reasons, we use a VPN connection. Another advantage is that we can monitor all device performance on a smartphone,” Keppels emphasized in conclusion.
