Guide Control

EMA felt and wire guide control units are equipped with electromotive adjusting elements with special motors.

EMA felt and wire guide control units

Advantages

Advantages compared to pneumatic systems are a.o.:

  • highest sensitivity in the adjusting sleeves (up to 1/10 mm)
  • clear separation between power element and control system
  • long run-time without adjustment (in practice run-times of several hours were achieved, in which the adjusting roll was not adjusted)
  • guaranteed convergence at twin wires
  • clear improvement of the feeding process at fast runners
  • absolutely straight web edge

Adjusting element

The electromotive adjusting element consists of a robust cast casing with a slide driven by a trapezoidal spindle. The adjusting element is optionally available for use in wet end sections of stainless steel DIN 1.4460 or in dry sections consisting of a steel case equipped with a coating system. The adjusting drive consists of a three-phase cage motor with increased resistance rotor, which means that the thermal stress in switching operation is extremely low.

Product advantages

  • robust design
  • maximum belt wrap at the adjusting roll 90°
  • arbitrary mounting position
  • maximum ambient temperature up to 150° C
  • low energy consumption
  • low-maintenance system

Funciton and technology

Control system

Our guide control units are as a standard equipped with Siemens S7-300. They can be connected to a process control system without problem via Profibus, Ethernet or RS232.

Centering

At being used in forming, press and dry sections the selected operating mode usually is “centering . Here the control system determines the neutral central position of the adjusting roll. An adjusting roll adjusted that way guarantees an extremely high run stability of the web.

Oscillator control system

In Foudrinier wire sections the operating mode ′oscillator control“ can be used, if a specific oscillation of the wire is required. Apart from that this operating mode is suitable for machines with coating systems for use in dry sections. In the operating mode with oscillation control the control system computes the neutral central position of the adjusting roll. Subsequently reversing of the web takes place by a very low correction stroke. By modifying the correction stroke the cycle time can be adjusted.

Web edge position detection

There are 3 variants for the detection of the web edge position

  1. Mechanical web edge position detection on one side. For slowly running paper machines we recommend this robust, trouble-free and at the same time reasonably priced solution.
  2. Mostly contactless web edge position detection on both sides. At paper machines with medium production speeds and high dirt accumulation we recommend the mainly contactless web edge position detection by means of two mechanical sensing units. The sensing units are positioned on the tending and drive side. By the control algorithm the neutral position of the web is computed and the adjusting roll positioned correspondingly. That way the web position indication only causes minimal edge wear.
  3. Contactless web edge position detection. At paper machines with high production speeds we recommend contactless web edge position detection, owing to which problems, e.g. edge wear, abrasion and mechanical detector wear will be avoided. Web edge position detection takes place on the tending as well as on the drive side. The system has a self-controlling function and is equipped with an error evaluation system. In dry sections the direct use of infrared reflection detectors is not possible. Here optical conductors are used, which transmit the signals of the infrared reflection detectors. Apart from that a mechanical pendulum detector monitors the outer web position.

Position indicator

The travel distance of the slide is shown as an analog signal by a position indicator. The potentiometer and the corresponding microswitch for the limit-stop device are accommodated in a robust casing. At extreme applications in the wet section the electromotive adjustment drive as well as the position indicator is protected by an additional stainless steel casings. By a scavenging air connecting piece the formation of condensed water is avoided.