Optimised maintenance of the extruder casing bores

A new type of wear-free measuring method for double worm extruders enables the non-contact measurement of the inside diameter of the casing bores. Specially developed for checking the bore in the machined section, the Idiamcontrol sensor system from Micro-Epsilon measures the profile diameter of the case bores. A measuring cylinder is passed into the case bore and pushed as far as the upstream end. Cross rollers are attached in front of and behind the measuring cylinder. 16 spring-loaded rollers guide and centre the measuring cylinder in the bore. The signals from the sensors opposite each other are converted to provide a diameter size in the controller.

During retraction of the measuring system, the diameter values and the distance covered are acquired and recorded via an evaluation unit. An interface for connection to a PC enables graphical evaluation of the signals. The measurement signal is displayed as a diameter over the complete length of the bore and tolerance deviations are displayed immediately.

For double worm extruders, the measuring cylinder has several metal pins that run along the saddle of both bores. In this way, twisting of the cylinder is prevented and exact recording of the measuring track is guaranteed. The recording of the diameter values can be carried out by turning the cross rollers through 40° for a total of six measuring tracks in a double worm extruder. Idiamcontrol is already used by several extruder manufacturers, including Coperion Werner & Pfleiderer. The system is also being used successfully at Leistritz Extrusionstechnik and at Berstorff GmbH. The case bore measuring equipment is often used for servicing work. Therefore, it is not necessary to dismantle the machined section, which means significant time savings are possible.

The measuring cylinder helps to optimise maintenance work on the extruder cases. Service intervals are increased due to precise knowledge of the condition of the case bores at any point.