Straightening Methods - The State of the Art

Rotor Straightening Machines for Reinforcement Steel and Wire

Fig. 1 Melc Monoline: Automatic straightening machine
with one rotor.Abb. 1 Melc Monoline: Automatische Richtmaschinen mit einem Rotor.

Fig. 2 Melc Flexiline: Automatic straightening machine furnished with patented, extremely fast rod diameter changing system.Abb. 2 Melc Flexiline: Automatische Richtmaschinen mit dem patentierten extrem schnellen Durchmesserwechselsystem.

Fig. 3 Sytheton: Automatic straightening machine based on the Flexiline principle combined with the twin bending system of
Eurobend.
Abb. 3 Sytheton: Automatische Richtmaschinen nach dem Flexiline-Prinzip kombiniert mit dem Eurobend Doppelbiegesystem.

Fig. 4 Melc Polyline: Automatic high-output straightening system with three rotors running simultaneously and bundling station.
Abb. 4 Melc Polyline: Automatische Hochausstoss- Richtanlage mit drei simultan arbeitenden Rotoren und Bündelstation.

Fig. 5 Melc Polyline: Automatic high-output straightening system with six rotors running simultaneously and collection system for the batches produced.
Abb. 5 Melc Polyline: Automatische Hochausstoß - Richtanlage mit sechs simultan arbeitenden Rotoren und Sammelmuldensystem für die produzierten Chargen.

 Eurobend S.A. has more than 20 years of experience in engineering and design of CNC machines and offers a wide range of equipment, such as, for example, 2D and 3D automatic stirrup benders, straightening and cutting machinery with one line or multi-lines, lattice girder and mesh welding machines, machinery for the production of continuously shaped (spiral) concrete reinforcing stirrups and much more.

The product range of reinforcement steel processing lines includes, among other things, a complete range of programmable high-output automatic straightening units for coiled reinforcement steel (type Melc), designed for continuous operation in the reinforcement steel industry.

Milestones of the technology in reinforcement steel production

The straightening method is based on the principle of a rotor with hyperbolically profiled cylinders (rollers) that has been designed and presented by the engineers of Eurobend in the early 80’s. This method has set new standards in the industry and it also led the way for other machine manufacturers.

The rotor straightening method with hyperbolically profiled rollers

The conventional straightening machines operate according to two different methods:

a) with various roller straightening systems or

b) with the conventional rotor straightening system with straightening dies

However, these systems have a number of disadvantages. The straightening quality achieved by the roller straightening systems is quite poor, which is a problem for many applications and it is therefore not acceptable if, for example, the straightened bars are meant for feeding mesh welding machines. Although the systems working with a rotor and straightening dies provide a good straightening quality, they damage the wire surface owing to the high friction. Moreover, they have to be adjusted very often during a shift, causing high maintenance and energy costs.

The method of Eurobend is based on a rotor, which – instead of straightening dies – is furnished with a set of hyperbolically shaped cylinders. These so-called hyperbolic rollers carry out two tasks simultaneously: wire feed and straightening as they are positioned at an angle to the wire axis rotating around the same.

Advantages of the Eurobend‘s system

This straightening machines of the Melc series offer a number of advantages:

» It is not necessary to adjust the hyperbolic rollers permanently.

» The best possible straightening quality is produced.

» The surface and the ribs are prevented from damage.

» Up to 40 % of energy are savings.

» Straightening of reinforcement steel consisting of a high wire strength (up to spring wire quality) is possible without an addition roller and feed system.

» The mechanic of the machine is simple: The rotor itself provides for both feed and straightening of the wire.

» The wire is cut by means of a flying shear without stopping the feed or slowing it down.

» The simple design of the system allows the manufacturing of machines with up to six rotor lines, that can be operated simultaneously and independent of each other. Each line is capable to process a different diameter and is furnished with its own measuring, cutting and discharging system. Each of the rotor lines working simultaneously is capable to machine a different batch.

» The different rotor sizes cover a diameter range from Ø4mm up to Ø35mm for reinforcement steel and stainless reinforcement steel.

» The multi-rotor configuration allows to process reinforcement steel in continuous operation of up to 500 m/min.

An innovative design concept meets all
requirements

Eurobend is in the position to offer the perfect machine concept from the Melc series with rotors of the new generation (4G rotors): depending on the size and the specialization of the customer (trader, bending shop, precast concrete plant or mesh manufacturer), depending on the working method applied in the factory (diameter-related or order-related) or according to the productivity required.

Melc Monoline series

This series offers models with a rotor having a feed rate of up to 120 m/min that covers the range from Ø4mm up to Ø35mm. The rotor is controlled by a frequency inverter; this allows to adapt it to the current requirements of a factory. The adjustment of the speed extends the service life of the wearing parts and the machine.

Furthermore, this series offers models equipped with torsion control and surface protecting systems, such as for manufacturing special reinforcement steel grades, as for example reinforcement steels of a very high strength, epoxy coated as well as Inox reinforcement steels.

Melc Flexiline series

This machine is the leading solution for precast concrete plants and factories that are manufacturing on an order-related basis.

Different models operate with three up to six rotors and a shared measuring, cutting and discharging line, covering a diameter range from Ø6 up to Ø20 mm. Cutting is effected by a flying shear (standard equipment of all Melc models). These models are the most flexible ones available on the market. The diameter can be changed in less than 3 seconds without moving, mechanical parts (patented). It is possible to produce large and small batches without any loss of time and logistical efforts, with each of them having different diameters and lengths.

The complete range of Flexiline – straightening machines – with integrated twin bending system – is marketed as Syntheton series and covers the diameter range of Ø6 – Ø20 mm.

The servo drive of the Syntheton double head bending system ensures an excellent precision both when bending and when positioning the bending heads. Right and left hand bends and the changeover of bending tools run fully automated.

Melc Polyline series

These systems are characterized by high-output straightening systems for large bending shops and mattress manufacturers. These types comprise three to six rotor lines that can be operated simultaneously and independent of each other. Each line can process a different diameter and is furnished with its own measuring, cutting and discharging system. Production speeds of up to 500 m/min are reached in continuous operation. It is possible to combine rotors of sizes from Ø4 mm up to Ø20 mm. The models of this series can be equipped with material handling and logistics systems. 