| 摘要 |
A retractable core for producing a relatively long casing section, in particular of floor-to-floor height, which can be cast from concrete, preferably from lightweight concrete, of a chimney casing which can be assembled from a plurality of casing sections is distinguished in that a hollow profile which serves as a core and the length and cross-sectional shape of which are equal to the internal cross-section and the length of the casing section to be produced has profile walls which are movable in the radial direction and in that actuatable adjustment elements for the movement of the profile walls are incorporated into the hollow profile. The adjustment elements comprise a shaft extending through the hollow profile eccentric discs arranged eccentrically on the shaft and projecting radially therefrom and a radial arm mounted on each eccentric disc, each of which radial arms is connected with an associated profile wall. With a rotation of the shaft the radial arms pull the profile walls connected to them inwards, reducing the cross-sectional profile of the retractable core.
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