Using embedded controllers to improve machine tool accuracy

Headquartered in Frauenfeld, Switzerland, Thalmann Maschinenbau AG manages sheet metal bending. The company entered the market in 1960. Following the first manually operated machine tool, it also successively introduced hydraulic drive and hybrid machine tools for sheet metal cutting and bending. Now, the company has been able to provide a variety of standard and special machine tools for forming metal plates up to 18.2m in length and can bend metal plates up to 3mm (400N/mm2).

Thalmann offers machines for small businesses as well as large industrial applications. “For example, industrial metal processing equipment uses our two-machine linkage bending machine to machine generator exterior wall panels and ICE train lane insulation panels. However, a small metal processing company purchased the same machine because they need to use custom wall panels. To the function of the double machine linkage bending machine,” explained Marco Cappello, global sales of Thalmann Maschinenbau.

Increasing precision is not as simple as it might seem at first: Dual-machine linkage bending process for metal forming The rotary folding process is used for hemming and contouring of sheet metal. This is a relatively gentle machining process. The bending beam rolls upwards around the fulcrum on the material without damaging the surface of the metal plate. The bending machine is usually composed of a bottom beam on which a metal plate is placed. The top beam presses the metal plate on the bent edge against the bottom beam, and the bending beam moves upwards, finally bending the metal plate to a desired angle.

Thalmann control axis technology ensures high precision bending. The precision of double-unit linkage bending machine is as high as ±0.5° (the basic model is ±1°), and the bending angle is up to 143°. Due to the use of high-performance hydraulic devices, it takes only three seconds to complete one-time adjustment. Outer and rotary strokes. The Thalmann TC and TD models are equipped with two bending beams; during the bending process the plates can be bent upwards and downwards without rotation. This can speed up the bending process and significantly increase the capacity of the bending machine. There are a total of nine axes that need to be controlled in a twin machine linkage bending machine.

CX series embedded controllers perform complex CNC functions The automation of the Thalmann press brakes is carried out by Regatron AG from Rorschach, Switzerland. Halmann has been successfully working with the company for 25 years. “The first control system we built (still currently in operation) is based on a hard PLC,” said Felix Lanter, manager of control and drive technology R&D at Regatron. However, as early as 1991, Regatron adopted the first PC-based control system, using MSDOS computers. Later, in 2003, they used the first industrial PC using Windows and Ethernet technology. IPC). "In 2010, we turned to using Beckhoff control technology." Felix Lanter continued. “The increasing level of sophistication in modern machinery requires control systems to change over time. The most important reason for choosing the Beckhoff solution is to consider that Beckhoff can provide a hydraulic software library when driving three servo motor axes and up to six other hydraulic axes. The software library will show great advantages."

Patrick Ruf, software programmer at Regatron, further explained the advantages of Beckhoff technology. “The CX1020 embedded controller can create an economical, scalable and technically high-quality control system. Suitable servo drives and analog bus terminal modules can be used for the drive shaft. In addition, we have created control solutions Great flexibility to choose from a variety of signals.For example, when it is necessary to meet customer-specific requirements, the control solution can also be extended.The software also has the corresponding flexibility; we use Beckhoff automation software TwinCATNCPTP We can continue to use the existing Windows-based user interface with ease. We can use TwinCATADS to make changes to the control system without major changes."

Integrated safety technology

"Of course, an important aspect of the press brake control solution is operational safety," explains Stefan Kern. To meet the mechanical safety standards, Thalmann uses the Beckhoff EL6900 Safety PLC terminal module that is seamlessly integrated into the EtherCAT terminal module system. The TwinSAFE solution has been SIL3 certified and complies with IEC61508 and DINEN ISO13849PLe standards. You can simply select and combine security features such as emergency stop, security door monitoring, and two-hand control. They can be easily configured in the standard TwinCAT System Manager and run as device programs on the same PC platform. The safety functions can be connected to the device program but are independent of each other.

According to priorities to upgrade

For equipment manufacturer Thalmann, they always put customer demand first. Therefore, they provide not the traditional standard equipment, but the customized equipment that takes into account the customer's needs. These equipments vary in size, length and function. "The range of customer requirements allows us to use components, systems, and control systems that can be modified appropriately," explains Marco Cappello. Stefan Kern's design director also holds the same view: “The complexity of equipment and control systems must be matched with each other best. At present, we are working on a project that, for cost reasons, must dispense with some functions. This allows us to use The basic model comes with a smaller range and more targeted features.”

This concept has important implications for the control solution, that is, it must reflect the needs of the device in programming. "On the other hand, we want to keep the design as uniform as possible," explained software expert Patrick Ruf. “When we designed the control solution structure, we considered that we could easily expand the scope of any function. We also tried to make all devices compatible with each other, so that even the oldest machines can be Updates."

EtherCAT Servo Driver: Dynamic Performance Control

The servomotor-driven bender shaft is controlled by Beckhoff's AX5000 Series EtherCAT drives. In terms of servo motors, Thalmann uses the Beckhoff AM3000 series wound motor. The hydraulic valve is controlled via the EtherCAT analog output terminal EL4001. The position and angular position of the axis is measured using the digital absolute encoder encoder EL5001. Device programming also includes a large number of monitoring functions that ensure trouble-free operation. For hydraulic oils, for example, whose temperature is monitored, the flow rate is measured and the oil filter is checked. "One big advantage of the Beckhoff Bus Terminals is that we can use them to control almost everything," said Felix Lanter.

Remote maintenance and diagnosis - new possibilities

Thalmann AG's bending machines are sold all over the world. In this regard, potential service options for PC-controlled devices have become interesting. “When Thalmann still stays in the past to provide traditional services, web-based teleservices, especially for the twin-machine linkage press brakes, are a very interesting alternative.”