Screening apparatus for paper making stock

Claim 1

A screening cylinder for use in pressure screening apparatus for removing contaminant particles from paper making stock and comprising a housing adapted to receive said cylinder and to have the interior thereof partitioned by said cylinder into a supply chamber and an accepts chamber respectively within and without said cylinder, and further comprising rotor means operative to circulate the stock to be screened within said supply chamber, said screening cylinder comprising: (a) a plurality of groups of circular rings of metal rod material defining a corresponding plurality of sections of the wall of said cylinder, (b) said rings in each said group being arranged in closely spaced relation axially of said cylinder to define a corresponding plurality of circumferentially extending screening slots of predetermined uniform width therebetween, (c) a plurality of metal bars of rectangular section extending generally lengthwise of said cylinder in uniformly circumferentially spaced relation around the interior of said cylinder and welded to each of said rings to maintain said rings in said axially spaced relation thereof, (d) said groups of rings being spaced axially of said cylinder to provide a corresponding plurality of gaps therebetween traversed by said bars, (e) a cylindrical metal hoop having a flat inner surface interposed in each of said gaps in encircling relation with said bars and having the same inner diameter as said rings, and (f) said hoops being welded to the portions of said bars which traverse said gaps to reinforce said cylinder as a whole.