1. Field of the Invention
The invention relates to a device for separating undesirable oblong and/or curved pieces of scrap from a scrap flow or scrap pile having a higher density by means of an oscillating or shaking screen.
2. Description of the Related Art
DE 33 19 032 C2 describes a device for screen separation of a pile of metal chips containing undesirable oversized material by using an oscillating or shaking screen provided with transverse slits, wherein the screen base includes longitudinal channels extending in the transport direction. The longitudinal channels have a trough-shaped cross-section with a defined flank angle. Alternatively, the channel cross-section can also correspond to a isosceles triangle standing on its apex and having a defined apex angle.
This prior art invention makes possible a highly selective sorting of the oversized material and an essentially uniform bulk density of the screen through-fraction. The material to be screened and/or the oversized material is hereby initially oriented transverse to the direction of the screening slits so as to ensure a length-dependent through-fraction that can subsequent be pressed into dimensionally stable chip briquettes.
It may therefore seem obvious to utilize such device also for separating so-called fishes, i.e., undesirable oblong and/or curved scrap pieces of chill scrap, which represents a scrap metal flow with a higher density. However, the association in the latter scrap metal flow is different from that in a pile of metal chips containing undesirable oversized material.
Oblong or curved scrap metal pieces are undesirable in chill scrap because they negatively impact the flow characteristic of the material. Moreover, clusters with a smaller density can disadvantageously form in the feeder devices of steel plants where chill scrap is used. If this unsorted pile of chill scrap were fed to the aforedescribed screen separation device for the purpose of separation, then the desired effect would not occur, because the existing geometric form of the screen cover would make it impossible to separate the so-called fishes.
It is therefore an object of the invention to provide a suitable screen cover in a conventional oscillating or shaking screen to enable sorting of the so-called fishes from chill scrap, wherein the separation elements are formed and arranged so that, on one hand, the so-called fishes, i.e., the undesirable oblong and/or curved scrap metal pieces, are oriented and, on the other hand, are separated from the desired more rounded and more compact scrap metal pieces.
This object of the invention is accomplished by providing a device for separating undesirable oblong and/or curved pieces of scrap material from a scrap metal flow or scrap metal pile which has a higher density. Scrap metal with higher density are, for example, chill scrap. The separation is accomplished with a screen cover in an oscillating or shaking screen. The screen cover is made of a plurality of parallel guide bars running in a longitudinal direction and a plurality of parallel separating bars running in transverse direction, and, thus, forming a lattice-like frame with openings through which the material passes. The device provides a) guide bars which rest on separating bars and project over the separating bars, b) the guide bars are formed of angle stock include longitudinal rails that are formed on or continue from free legs of the angle stock, with their mutual separation on the free longitudinal sides being smaller than their separation at the free legs of the angle stock, so thatxe2x80x94as seen in cross-section of the longitudinal railsxe2x80x94openings are formed which have a width that increases from top to bottom, and an essentially trapezoidal cross section, c) the transverse separating bars have flank strips which project into the openings and rise in the transport direction of the undesirable scrap metal pieces, so thatxe2x80x94as seen in cross section of the separating barsxe2x80x94the openings have a cross section in the shape of a parallelogram, and d) the openings are thereby delineated both by the opposing longitudinal rails as well as by the opposing flank strips. Further, at least one rear wall is provided for each opening on the flank strip.
The invention will now be described in detail with reference to an embodiment illustrated in the drawing.