Field of the invention

The present invention relates to a bendable cylinder, especially a spreader for the spreading of a web-like material, said cylinder comprising a continuos tube-like cylinder jacket of composite material and a fixed axle part on which the cylinder jacket is mounted with bearings, and which cylinder addition¬ ally comprises a bending mechanism for bending the cylinder jacket. Bendable composite cylinders with a jacket of composite material are used especially as spreaders in paper and cardboard machines. A compos¬ ite cylinder has advantageous material properties, in particular coefficient of elasticity and density, and thus it can be so dimensioned as to make it relatively easily bendable to a desired curvature.

Prior art

Specification FI-B-103 071 discloses a bendable cylinder for web- like material, comprising a tube-like cylinder jacket of composite material and fixed, i.e. non-rotating spindles attached to either end of the cylinder jacket. The spindles are fastened via two supporting points to a fastening flange structure fixed to the machine frame. The cylinder additionally comprises a bending mechanism placed outside the cylinder jacket and used to bend the spindles and the cylinder jacket to an arched shape, and a control device allowing the angular position of the cylinder arc to be adjusted. A drawback with the solution according to this specification is rela¬ tively complicated structure and installation. In addition, it takes up a relatively large space at the side of the cylinder jacket. Moreover, in prior-art solutions, implementing the suspension with bearings between the spindle and the cylin- der jacket is a complicated and difficult task especially in respect of installation.

Brief description of the invention

The object of the present invention is to overcome the drawbacks of prior art and to achieve a completely new type of composite cylinder construc¬ tion. In the construction of the invention, both bearings are fitted in a protective sleeve provided inside the cylinder jacket, thus producing a very compact and simple bending system. It can be easily mounted as a unitary module inside the cylinder jacket. The features of the solution of the invention are presented in detail in the claims below.

Brief description of the drawings

In the following, the invention will be described in detail with refer¬ ence to an example and the attached drawing, wherein Fig. 1 presents a composite cylinder according to the invention, Fig. 2 presents a second composite cylinder according to the inven¬ tion, and Fig. 3 presents a third composite cylinder according to the inven¬ tion.

Detailed description of preferred embodiments

Fig. 1 presents a cross-sectional side view of an end part of the composite cylinder, which comprises a continuos cylinder jacket 1 of composite material and inside it a central shaft 2 going through the cylinder jacket and hav¬ ing a thicker middle portion 21 and thinner end portions 22 (inner) and 23 (outer). Between the inner shaft portion 22 and the jacket 1 is a protective sleeve 30 (outer bushing) fitted nearly completely inside the cylinder jacket, said sleeve being fixedly fitted inside and at the end of the cylinder jacket 1. Fitted inside the protective sleeve 30 at either end of it are bearings 31 and 32 and inside these a bushing or ferrule 33 (inner bushing) fitted nearly completely in¬ side the cylinder jacket. In addition, the cylinder is provided with a bending mechanism arranged in the bushing 33 for bending the bushing 33 and the cyl- inder jacket 1 and for adjusting the bending action. To this purpose the outer end of the bushing 33 is provided with an adjusting screw 5 connected by threads 4 to the end of the shaft portion. Moreover, the inner end of the bushing 33 is pivotally connected by a ball bearing 6 to shaft portion 22. The bending (magnitude of curvature) of the cylinder is adjusted by turning the adjusting screw 5, thereby changing the angular position between shaft portion 22 and the bushing 33, and as the motion of the bushing 33 is transmitted via the bear- ings 31 , 32 to the jacket part 1 , the angular position between the jacket 1 and shaft portion 2 is changed at the same time. In the solution of the invention, the other inner bearing 31 is also ar¬ ranged between the sleeve and the cylinder jacket near the inner edge of shaft portion 22 in a position aligned with the ball bearing 6, the entire bearing and bending system thus forming a single unitary module 3, which can be mounted inside the cylinder jacket. In addition, the cylinder comprises a worm gear 7 provided with a rocker bearing, mounted at the end of the shaft, allowing the direction of the arc to be turned. In Fig. 1 , the bending forces are received by the shaft. In principle, the other end part is identical except that axial forces in the bearing arrange¬ ment are released in the structure in question. Figures 2 and 3 present other bendable cylinders according to the invention, of which the cylinder in Fig. 2 also has a shaft going through it and a worm gear 8 its end, whereas the cylinder in Fig. 3 is provided with spindles 9 having a thicker inner portion 92 and a thinner outer portion 93 and additionally a worm gear 10 at the end. In the solution in Fig. 3, the bending forces are completely transmitted to the frame, and in Fig. 2 they are divided between the shaft and the frame. It is obvious to the person skilled in the art that different embodi¬ ments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below.