Classifying – separating – and assorting solids – Sifting – Elements
Reexamination Certificate
1999-03-17
2001-07-03
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Elements
C209S405000, C209S408000, C209S409000
Reexamination Certificate
active
06253926
ABSTRACT:
The present invention relates to screening apparatus and more particularly to a modular screen panel for use in such apparatus.
Screening apparatus of the type with which the invention is concerned is generally used for screening, grading, or separating materials such as ores and comprises an array of screen panels removably fixed to a frame to provide a continuous screen deck. This deck is vibrated to move bulk materials over and through its screening surface and generally it is desirable that the screening surface be resiliently flexible such that the vibration of the frame sets up a secondary vibration in the screening surface. This secondary vibration is desirable because it assists in overcoming the problem of the screen becoming clogged. However the panels must also be sufficiently stiff to support the material and provide for structural integrity of the apparatus.
It is known to form screen panels in one piece by moulding a resilient plastics material. However a problem with these moulded panels is that stiffness is provided at the expense of flexibility and generally the provision of a requisite degree of stiffness results in the screening surface of the panels having a low degree of flexibility. It is also known to provide stiffness by embedding steel reinforcement members in the plastics material along the sides of the panel, as exemplified by Australian Patent No. 577767 (66006/86). However this increases the expense of the panels, which are consumable items.
The screen panels in a screen deck can be subjected to quite harsh wear, depending on the materials being screened, and thus require periodical replacement. Indeed, the ready exchangeability of worn screen panels for new panels is characteristic of screening apparatus of the type with which the invention is concerned and is a factor which has led to reduced operating costs for such apparatus. However the cost of individual screen panels remains as a significant component of the operating costs for this apparatus.
It is an object of the present invention to provide a screen panel which may have a relatively highly flexible screening surface and which allows for a significant reduction in the replacement costs for a panel.
According to a first aspect of the present invention there is provided a screen panel module for mounting on a screen deck frame for screening, separating or grading materials such as ores, the module including: a resiliently flexible panel component providing a screening surface; a frame component on which the panel component is removably mounted, the frame component fitting under and providing a stiff support for the panel component; and means along at least two opposite sides of the module for interengaging with fixing means for locating and fixing the module to a screen deck frame.
The means for interengaging with fixing means may be provided by the panel component, the frame component or both components, preferably, however such means are provided by both the panel component and the frame component.
Other aspects of the invention include the provision of a panel component per se, a frame component per se, and screening apparatus that includes at least one of the modular screen panels.
The frame component may be a square or rectangular shaped moulding of resilient plastics material and may include reinforcing members embedded in the plastic. The panel component may also be moulded from a resilient plastics material and preferably includes a depending flange along at least two opposite sides, wherein each flange includes elements for interengaging with complementary elements along corresponding sides of the frame component for removably mounting the panel component on the frame component. These interengaging elements may be ribs, grooves, beads or the like for providing a snap fit engagement action for the panel component on the frame component. Preferably each side of the frame component includes a groove and each depending flange of the panel component includes a complementary rib for seating in the grooves. This removable interconnection for mounting the panel component on the frame component to form a screen panel module does not employ or require any additional or external fixing means and allows ready and easy interchange of a panel component on a frame component. Although both the panel component and the frame component are subject to wear, the panel component wears much more quickly and thus requires more frequent replacement than the frame component. The invention allows for this frequent replacement of the worn component to occur independently of replacement of the frame component and it will be understood that this confers a significant saving in the maintenance costs for screening apparatus that employs two part modules according to the invention. Whereas the whole of a prior art screen module has to be exchanged when worn, the invention allows the exchange of only one component of a module which component costs a fraction of the whole module.
The invention also allows manufacturers more scope to tailor the properties of the panel component to suit particular applications or materials. Thus its flexibility and/or surface hardness characteristics may be established independently of the frame component. Furthermore, the means for removably mounting the panel component on the frame component, particularly a snap-fit type of interconnection as described above, does not reduce the flexibility of the interconnection to the same extent as occurs with prior art integrally moulded panels. For example, for a screen module that is to be used for screening bulk material having a high clay content, which tends to be sticky, the panel component can be made sufficiently flexible and be removably mounted on a frame component such that the secondary vibration in the screening surface is of greater amplitude than that which occurs in prior art panels. This greater amplitude secondary vibration reduces the problem of the clay-like material binding to the screening surface and clogging the screen.
Preferably the means along the at least two opposite sides of the module (which will be the sides that don't include the means for removably mounting the panel component on the frame component) for interengaging with fixing means for locating and fixing the module to a screen deck frame, are also elements in the nature of ribs, grooves, beads or the like for preferably providing a snap-fit engagement action for the screen panel module with complementary elements on the fixing means. The fixing means preferably includes a U-shaped fixing rail attached to the screen deck frame and an elongate retaining member for plugging into the channel provided by the U rail. Preferably both the fixing rail and the retaining member include elements in the form of ribs and grooves for interengaging with complementary ribs and grooves on both the panel component and the frame component of the screen panel module.
This preferred form of fixing means for the panel module, wherein both the frame component and the panel component are engaged, provides a more secure fixation for the module than would be the case if only the frame component or the panel component were engaged, although the invention encompasses embodiments wherein only the frame component or only the panel component is engaged. The preferred form of fixing means also allows for ready removal of a module from the screen deck. Thus, the invention allows for quick removal of a module from a screen deck and quick replacement of a worn panel component of that module, followed by quick replacement of the “repaired” module in the screen deck.
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patent: 4674251 (1987-06-01), Wolff
patent: 4757664 (198
Jones David A
Lettela Pty Limited
Merchant & Gould P.C.
Walsh Donald P.
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