Comeco

Precise Bending at the Touch of a Button

Intelligent Drives For Bending Machines

Structural steel bending, which usually happens at the construction site, is done by efficient, quiet, compact machinery. Comeco has replaced the original hydraulics with an electric drive solution with integrated PLC from NORD DRIVESYSTEMS. The Swedish machine manufacturer has already updated equipped the second series of machinery. And a further one is already in development.

Fredrick Hallberg places rebars of 32 mm thickness between two bar guides on the rotary table, and after starting the motor, the plate rotates with a gentle whirring sound and bends the rigid bar as if it was made of dough. Deciding the shape of the bar is simple and effective.

From Discovery to Partnership

Hallberg is the owner and CEO of the Swedish mechanical engineering company Comeco. What he is demonstrating here is what is usually done directly at construction sites: Before the steel bars can be used to form meshes or reinforcing cages, they have to be bent into the right shape, this can vary from construction project to construction project. Precise bending is therefore mostly carried out by construction workers on mobile stirrup bending machines that are operated manually – as manufactured by Comeco.

Comeco is a small company based in the Swedish town of Enköping near Stockholm and Uppsala. In 1991, the machine manufacturer started with manufacturing radiant heaters for the construction industry, cutting and bending machines for rebars were added to the to the portfolio in 2009. The main customers are construction machinery rental companies, which account for 80 percent of the business. That makes it clear: Ideally, the machines should be compact, easy to transport and simple to operate for the different users – characteristics that Hallberg wanted to improve on his hydraulic machines.

“Around 2015, we wanted to further develop our machines to make them more service-oriented, safe and quieter”, he explains. “Back then, we coincidentally came across one of our older machines which had a name plate from NORD on the drive.” The contact to the system supplier for drive solutions was established and Hallberg decided to replace the hydraulics in the next Comeco machine with an electronic drive system from NORD. After the first bending machine for rebars with a diameter of 16 mm was successfully introduced, Comeco also developed machines for 20 and 25 mm rebars. More recently, the machine for 32 mm rebars was developed and launched, this was being presented by Hallberg.

Reduced To The Esssentials

Two values are crucial for stirrup bending machines. On one hand, the angle that the rebar has to follow must be specified, and on the other hand, the motor speed decides at which force the rebar is bent. “The old hydraulic solution was quite mechanical”, Jonas Bergvall from the NORD Sales Team in Sweden remembers. “The bending machine was set with manual adjustment screws. Once set, it always required a test bending run in order to check that the angle was correct.” Additionally, the electrics of the hydraulic concept was very complex which made maintenance time-consuming and only few employees were able to carry it out. The overall large design footprint and heavy sound pollution only made it more difficult to operate.

The NORD solution reduced all this to the essentials. It consists of a 3-stage 2.95 hp UNICASE parallel geared motor with an encoder. With its slim design, it is especially suitable in a compact installation space. Its UNICASE™ housing concept ensures long life cycles and low maintenance. Despite its compact size, it supplies torques of up to 30,977 in-lb. A NORDAC <i>FLEX</i> SK 210E variable frequency drive with 2.95 hp is mounted directly on the geared motor. The variable frequency drive is operated through the parameterization unit and provides a comprehensive functional safety package. It is NORD’s most flexible variable frequency drive, and can be tailored to any application due to its modular structure. Instead of complex wiring of the hydraulic control system, the electronic drive only needs mains power connection. All the machines required functions and movements are controlled by the integrated PLC of the NORDAC <i>FLEX</i> – a requirement by the customer Comeco.

Convincing User-Friendliness

The NORD drive solution convinced with its user-friendliness and ease of operation. The user sets the speed, angle and operating mode via arrow keys on the control display, navigating through various menus is not necessary. Six different Preset bending angles can be chosen via the knob on the machine, allowing several rebars to be processed in succession. You can also choose the angle yourself by using the display.

Upon starting the bending process, the gear unit moves the rotary table with the setpoints which causes the bar guides to bend the rebar into the specified shape. By using pre-programmed controllers, six different bending presets can be selected and saved via the PLC, allowing several rebars to be processed in succession. When required, additional individual specifications can be set on the display.

“With a joint effort, we worked on making the system as streamlined as possible”, says Bergvall from NORD. The parameterization unit simplifies machine operations. NORD can program the parameters “The number of digital inputs at the frequency inverter is limited”, explains Bergvall. “We have carried out extensive programming and can now offer the same functionality with fewer used digital inputs.”

Complete Drive Solutions from a Single Source

Comeco relies on NORD as a system supplier and obtains the entire drive solution from a single source. This has reduced the assembly times for the bending machines by almost half. The drive solution itself turned out to be a factor of success for Comeco. “At the moment, we are the only manufacturer of this type of machine. It is a small niche in which we are operating”, says Fredric Hallberg. And this is where Comeco wants to expand. The company currently sells the bending machines primarily in Sweden, Norway and Finland. Hallberg’s goal is to also sell the machines in other European countries.

He wants to continue his path together with NORD. “NORD very quickly meets our requirements and develops the drives that we need”, he says. “The existing cooperation was exemplary and will be continued.” With the scalable PLC, a bending machine for the next size of rebars will soon be introduced into the market. It will be able to bend rebars with a diameter of 40 mm. In addition, the entrepreneur wants to also integrate NORD solutions in his machines for rebars cutting.