The Driving Force Behind Success

Swedish manufacturer Comeco offers bending machines for different rebar diameters to suit demands of construction and rental companies. The company used hydraulics in designing rebar benders, a common choice for such machines. But the specialists for construction-site machinery found several problems with the tried and tested technology.

Fredric Hallberg, Owner & Manager, Comeco, shared, “Installing the hydraulic power unit, piping network, and sensors took a lot of time. The machine design was much more complex and more prone to problems than our new electromechanical machines.”  

Comeco therefore researched ways to make the machines more robust and ideally cheaper to build. That is when Hallberg chanced upon the Nord brand when he was giving another bending machine a closer look which had Nord components
in it.

High usability

As per Comeco’s requirements, all machine functions were to be controlled by a PLC. Nord  therefore, proposed its NORDAC FLEX AC vector drive. The motor-mounted inverter integrates a PLC for precise speed control and positioning. Machine operators can select from two speed settings according to their skill level and the thickness of the steel bar. The 20 mm machine allows two angles to be programmed at a time. Operators can then conveniently go from one setting to the other with a switch button. The parallel-shaft geared motors of these drive systems deliver high torques at a very compact size.

The drives are delivered pre-assembled and pre-parameterized with a Parameter Box, which Comeco takes as is and installs in the machine operation panel. Instead of complex wiring of the hydraulic control system, the electronic drive only needs a power connection. “We certainly save money here as well,” said Hallberg.

“The ParameterBox saves us a lot of switches. The company delivered it with the buttons and the display programmed according to our specifications. You change the angle with the up and down arrows, the speed with right and left. It is very simple. Operators do not need to navigate through a menu.”

Safety first

After bending, the PLC reverses the drive for easy and safe removal of the rebar. “The simpler machines do this by means of springs. A spring is another mechanical part that can fail. We prefer our new state-of-the-art electronic solution. It is much safer,“ said Hallberg. In addition to an emergency stop button, the machine also stops if a plate near the infeed is touched – for instance, because a glove has been caught on a rough metal part. “One advantage of using Nord instead of hydraulics,” he added, “is that the motor is not jammed. That way, you can manually remove the piece of rebar.” The gears run so smoothly that removing an obstacle from the machine in any direction is not a problem.

Knowing NORD

In addition to standard drives, Nord Drivesystems supplies application-specific concepts and solutions for special applications. The company produces a wide variety of drive units for torques from 10 to 200,000 Nm, electric motors with powers from 0.12 kW to 1,000 kW as well as the necessary power electronics in the form of frequency inverters and servo controllers. Inverter solutions are available for classical installations in the switch cabinet and for decentralized and fully integrated drive units.

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