Karl Fuhr GmbH & Co. KG (Horn-Bad Meinberg) is now universally equipping the rolling plants for flat and profile wires with Siemens control and servo drive technology.

Fuhr's universal turks head can be quickly and precisely setup for the widest range of square and rectangular wire profiles.

A prelaying unit, also servomotor-driven, feeds the wire precisely down to the coil base and into the corners to produce a uniform, clean winding pattern that ensures the problem-free further processing by the end user.

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"Keep it simple": Although essentially complex, Fuhr rolling plants can be set up fast and easily. An automatic edge stop compensation relieves work from the operator.

Seamless: The EW-Tec automation company uses in preference the integrated Siemens control and drive technology because this is accepted and available everywhere and quickly throughout the world.

The machine constructor generates from the modular Sinamics S120 drive family tailored drive solutions for its rolling devices and installs these in separate switchgear cabinets.

Servos on the complete line

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Since 1946, rolling technology for the cold and hot forming of wires has been the special area of competence for Karl Fuhr GmbH & Co. KG based in Horn-Bad Meinberg in Lippe (North Rhine-Westphalia). Core competencies of the company with 45 employees are still the development, production (with a high production depth), assembly and commissioning of complex rolling plants and single aggregates, such as trailing rolling apparatus, feed facilities and coiling machines. Business is heavily dependent on export with approximately 80% of the production going to foreign European customers, larger percentages of which go to USA and Japan. Leading companies from the automotive, electrical, food processing, textile and building industry use Fuhr rolling technology throughout the world to produce profile, flat and round wires made of stainless steels, ferrous and non-ferrous metals for the further processing to produce the widest range of products, from HSS bandsaw and jigsaw blades, including transformer windings, through to piston rings for the automotive industry.

In principle, all these products can be manufactured on the same rolling plant; after all, in addition to precision and economics, flexibility is one of the most important development goals at Fuhr. The decisive advantage is realized there through the continuing use of state-of-the-art technologies that the control and drive technology, in particular, offer. The latest innovation step in this direction was the substitution of proven stepper motors with the latest drives of the modular Sinamics S120 series and Siemens 1FK7 synchronous servomotors at all adjusting axes for profile rolling machines. Most versatile and powerful representative of the Fuhr program is the WST universal profile rolling machine – also designated as universal "turks head". Its four cylindrical rollers can now be positioned individually with servomotors and so dynamically and with high precision in both the axial and the radial direction. This permits a very fast change of dimension without needing to replace the roller sets each time. The dimension change time is also reduced thanks to the full utilization of the rated speed (up to 1,000 RPM) of the servomotors for the default setting of the rollers in rapid traverse. On the other hand, even slower lateral traversing ("changing", see below) of duo rolling plants is possible with positive effects on the tool downtimes.
The rollers are "calibrated" automatically during the installation and the actual dimension transferred to the controller. This means the roller diameter generally no longer plays any role. The ability to use simple cylindrical rollers keeps low the tool costs and also the effort for the tool maintenance.
The user can enter the required rectangular or square wire dimensions and also the air gap and its position on the visualization system, a Simatic MP277 or MP377 Touch Multi-Panel (depending on the number of stands/axes of a line), and the servomotors bring the rollers fast in the appropriate position to each other.
The central Simatic S7 300 PLC (normally with S7 317 2 PN/DP CPU) that calculates and coordinates the adjustment and feed movements at the roller stands communicates using Profibus DP with the CU320 control units of the Sinamics converter system and also individually positions the axes. The PLC-based method of the motion control was retained intentionally. This allows proven function blocks and the available know-how to be reused and the development time reduced.
The measuring system at the outlet of the associated last roller stand continuously records the actual dimension of the wire and passes this to the controller, which, in the case of deviations from the setpoint, can intervene fast and targeted. This allows a constant high and always reproducible dimension accuracy of the wires down to ± 3µm even for throughput speeds as fast as 500m/min.
"Except from the rotary position transducers for the servomotors designed to withstand dust and spray water in the IP65 degree of protection, nowadays, our rolling plants no longer have any sensory systems that can be impaired by coolants and/or abrasion", emphasized graduate engineer Volker Gerth, Fuhr CEO.

The modular structure of the Sinamics S120 drive family with separate infeed, open-loop control and single- and double-axis motor modules supports Fuhr's modular machine construction. This allows tailored drive groups for each rolling stand to be easily constructed in separate switchgear cabinets – for example, with a Sinamics CU320 control unit and two double-axis motor modules for four axes of the simpler roller devices or twice the number for a universal turks head with eight servo/adjusting axes. This allows the switchgear cabinets to be standardized and simply combined with each other to produce individual rolling lines. The main switchgear cabinet is connected with the central controller using Profibus without requiring any large wiring effort.
Separate drives for each individual roller also permit different operating modes. This allows a universal turks head with the appropriate form rollers also to be used for profile rolling or, after the removal of the side rollers, as simple duo rolling stand. In the latter case, the upper and the lower roller can continually change transversely in the axial direction. This minimizes “running marks” on the rollers with the resulting impairment of the wire surfaces. This also significantly increases the lifetime of the rollers and they only need to be reground significantly less frequently, which in turn reduces the replacement times and downtimes.

EW-Tec Industrieservice & Anlagentechnik GmbH based in Nettetal planned and realized the new automation solution. The company managed by Wilfried Weyers was founded more than ten years ago and currently has 15 employees. Focal areas of the work for manufacturers of rolling plants, coating plants, calenders and special machines active worldwide are the electrical engineering and the realization of complex automation solutions, including switchgear cabinet construction, data acquisition and network integration of the systems. Another mainstay is electrical and automation technology retrofits in the mentioned industries and areas. "Provided the customer allows us, we have always preferred Siemens automation technology", said Wilfried Weyers, "because we have very good experience here and the support functioned in every project phase and aspect." This allowed even this first SINAMICS application to be completed successfully quickly after a brief familiarization and telephone support by Siemens for specific points.
Matched control and drive components from a single source mean high function reliability even from the beginning. The machine constructor also profits in future with Siemens as global player being present almost everywhere throughout the world. This means spare parts and support can be also made directly available at the end user site should this be necessary.

EW-Tec has also innovated the laying of the wire at the end of a rolling line and, based on the "laying unit" application example for the Simotion D motion control system, developed a Fuhr-specific application. The aim here was to achieve the simplest possible and user-friendly handling and operation. Consequently, a system for the automatic alignment of the wire coils (using either lasers or light barriers) was created. The coil core diameter and maximum opening between the flanges are continually recorded at the rotating coil. The system detects any eccentricities or compliance of the flange, sets the coil start and end accordingly, and, if necessary, adapts the switching points even during the running operation. The operator specifies only the wire width (laying step) and starts the automatic edge stop compensation. Together with the automation company, the Fuhr engineers have packed all important process parameters in a mathematical model that automatically determines and recommends the optimum parameters for injection height and angle, offset and acceleration angle. The programming in the Structured Text high-level language with the Simotion Scout engineering system also proved to be very simple and flexible, even for changes, emphasized EW-Tec's programmer, Hubert Kreft.
Despite all the simplicity, the fitter has many intervention capabilities to modify the rolling and laying task as required, for example, for setting up new or very sensitive products. The developer, however, expects this to be more the exception, because the automated method has previously produced very good settings right from the beginning.
A Siemens SimotionN D410 DP motion controller (here added to a Sinamics PM340 power module) forms the central component of the laying unit. The device designed for precise single-axis applications was selected because of its integrated synchronous and cam function. It calculates highly dynamically the axial traversal movements of the laying head required for an optimum coiling pattern and synchronizes these precisely to the rotational movements of the laying unit's main axis. The laying head can be moved traversely using a linear motor or with a servomotor and ball screw.
For certain applications, the machine constructor has developed an additional prelaying also controlled with servomotors from the central PLC. This is a stable positionable wheel, controlled in the axial direction, on which the product is alternately exactly guided on the left- and right-side down to the coil base and in the side end positions. This guarantees an absolutely clean, stable coiling pattern even for very small wire dimensions and so provides the best prerequisites for the subsequent further processing by the end user.
The laying unit can be operated and monitored either at the central mobile panel (preferably during operation) that can travel along the machine or from an additional Simatic TP177 touch-panel directly on the laying unit (in particular for the setup). Previously optimized settings (using WinCC flexible standard functionality) can be stored as "recipe" in the central operator panel and, when required, archived using the network connection. For example, on the "service PC" that Fuhr always recommends, not only for more complex rolling plants with as many as ten stands and 60 individual axes.

Another reason for the transition from the stepper motor to the servo drive technology was the ability to implement significantly easier and more efficiently the remote diagnosis and maintenance of the plants used worldwide. For this purpose, all required engineering tools, such as Step7, Scout, WinCC flexible and Drive ES, are installed on the service PC so that the service technician always has the correct software versions, even for remote access. The service PC is connected with the Simatic controller and the multi-panel of the rolling plant using Ethernet. The Sm@rtService option package for the WinCC flexible.... This gives the authorized service technician fast and complete access to all functionality of the rolling plant down to the drive parameterization using the network connection. "Previously, a time-consuming procedure, because, unlike now, it is not possible to simply route through to each individual stepper motor, but instead first establish a direct connection and install the tailored drive software for each motor", stated Wilfried Weyers. Consequently, the new concept significantly accelerates not only the initial commissioning but also any subsequent changes.

The upgrade from the stepper motor to the Siemens servo drive technology was performed just as easily. Until now, all operating companies have universally agreed on the positive assessment of such realizable results. Currently, the more powerful of the available Simovert Masterdrives VC converters previously also used for the transport drive, the unwinding and winding is being replaced by the newer Sinamics drives. This realizes an integrated, more efficient and lower cost complete solution.