The present invention relates to a new and improved construction of a centrifuge sieve or screen which is provided at the inner surface or wall of a centrifuge drum with a support arrangement supporting sieve or screen rods which are formed of a wear-resistant material and extend in the axial direction of the centrifuge drum. The present invention also relates to a new and improved method of manufacturing a centrifuge sieve or screen of this type.
With such type of centrifuge sieves or screens, which are known to the art, for instance from U.S. Pat. No. 4,313,992, granted Feb. 2, 1982 or U.S. Pat. No. 4,259,136, granted Mar. 31, 1981, the sieve or screen rods which protect the centrifuge drum against wear are mounted by adhesive bonds to the support arrangement of the centrifuge drum. For the purpose of compensating for the different thermal expansions of the sieve or screen rods and the support arrangement which are composed of materials having different coefficients of thermal expansion, there are provided for the connections elastic intermediate layers, for example, rubber intermediate elements. However, during operation such elastic intermediate elements do not possess a sufficient service life. Additionally, they allow for a mobility in a number of directions, resulting in undesired and impermissible deformations of the sieve or screen rods and the support arrangement with respect to one another. Additionally, what is further disadvantageous with this equipment design, is the difficult assembly of the sieve or screen rods on the inside of the centrifuge drum or, respectively, the support arrangement, something which is particularly unsuitable for mass production.
Another construction of centrifuge as known, for example, from U.S. Pat. No. 3,100,746, granted Aug. 13, 1963, possesses similar disadvantages. Here the sieve or screen rods loosely rest in a groove at least at one end thereof. Also in this case there is thus possible an uncontrolled mobility and deformation of the sieve or screen rods. Additionally, operation of the centrifuge is only possible with its lengthwise axis oriented in vertical direction and only by using a conical design of the centrifuge drum, in order to prevent the sieve or screen rods from falling out.
In another suggestion for a centrifuge sieve as known, for example, from European Patent Publication No. 71,012, published Feb. 9, 1983 and the aforementioned cognate copending U.S. application Ser. No. 06/395,142, now U.S. Pat. No. 4,430,221, the sieve or screen rods are fixedly connected to the support arrangement only at one place or location while they are connected thereto at other places or locations by means of, for example, slots so as to be movable in axial direction. This suggestion also has certain disadvantages; specifically, the exchange of defective or worn-out sieve or screen rods is troublesome and the manufacture of such a centrifuge sieve is complicated and associated with a great deal of work.