Metall

Magnetostrictives position sensor for bending machine

How to check in real time and with excellent resolution the radius of curvature impressed by the two lower rollers, driven by hydraulic cylinders, of a bending machine

Passende Produkte

WPG-A
Wegaufnehmer in Profilbauform - Basisausführung

The WPG-A magnetostrictive position sensor is the ideal position sensor for controlling the position of the bending rolls:

  • ensuring linear positioning repeatability of 0.01 mm;
  • resolution up to 0.5 𝜇m,
  • signal linearity: 0.04 % FS;
  • simplicity in assembly by means of metal brackets even for small dimensions.

Overview

  • Product: WPG-A magnetostrictive transducer – 350 mm stroke
  • Customer request: control of the bending rollers position with a repeatability in a range between 0,2 and 0,3 mm.
  • Result: WPG-A has enabled the position control of the moving rolls with a repeatability of 0,01 mm.

The process

A roll bending machine bends cylindrical metal profiles into circular arcs, usually following a single angle/bending radius.

In double pitch roll benders instead (Figure 1) the two lower rolls can move to define the inlet and outlet bending radii, with the central one fixed.

In the most advanced machines a PLC allows the conversion of the bending radius and the pipe dimension into the actual degree of bend displayed on a HMI.

In addition, on the two sides there may be adjustable supports to make the bending more stable and precise.

Figure 1 – Process scheme

The challenge

In the case of a double pitch bender, the machine needs to control in real time and with excellent resolution the radius of curvature impressed by the two lower rolls, driven by hydraulic cylinders.

Since a small variation in their reciprocal positioning of the rolls causes a completely different bending angle, only a repeatability of the linear positioning from 0,2 to 0,3 mm in combination with high accuracy, can ensure the production of batches of the highest quality.

In addition to these technical needs, the position sensors required must be absolute and not incremental, in order to provide the roll position immediately when the machine is switched on.

Last but not least, the transducers to be paired to the cylinders should be easy to install, with reduced dimensions but also cost effective so that it can be adopted by entry-level machines.

Product benefits

  • Repeatability of the linear positioning of 0,01 mm
  • Resolution up to 0,5 𝜇m
  • Signal linearity: 0,04% FS
  • Easy mechanical installation by means of metal brackets

Solution

WPG-A magnetostrictive transducer to control position of bending rollers

Transducer stroke: 350 mm, aluminium profile

Repeatability: 0,01 mm

Resolution: 0,5 𝜇m

Figure 2 – Product: WPG-A magnetostrictive position transducer