Classifying – separating – and assorting solids – Sifting – Elements
Reexamination Certificate
1999-10-01
2001-04-24
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Elements
C209S403000, C209S392000, C209S409000
Reexamination Certificate
active
06220449
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to filtering and classifying material with vibratory separators and shale shakers; to screens for such separators and shakers; and to such apparatuses useful for both dewatering and classification.
2. Description of Related Art
Vibrating screens have been employed for many years to separate particles in a wide array of industrial and oilfield applications. One common application of vibrating screens is in drilling operations to separate particles suspended in drilling fluids. The screens are generally flat or three-dimensional and are mounted generally horizontally on a vibrating mechanism or shaker that imparts either a rapidly reciprocating linear, elliptical and/or circular motion to the screen. Material from which particles are to be separated is poured onto a back end of the vibrating screen. The material generally flows toward the front end of the screen. Large particles are unable to move through the screen, remaining on top of the screen and moving toward the front of the screen where they are collected. The smaller particles and fluid flows through the screen and may be collected in a pan beneath the screen.
A vibrating screen may be formed from one or more layers of screening material, screen and/or wire mesh, which are generally described with reference to the diameter of the wires from which they are woven, the number wires per unit length (called a mesh count) and the shape or size of the openings between wires. The type of mesh chosen depends on the application. The screening material in certain prior art screens is mounted on a frame, a perforated plate or perforated panel.
Some screens use wire mesh that is tensioned. Tensioning (accomplished in a variety of ways, e.g. with hookstrips and/or pretensioned panels) restricts movement of the wires and assists in holding the shape of the wire mesh.
Multiple layers of mesh may be used to alleviate blinding. U.S. Pat. No. 4,033,865, describes layering two meshes in a manner that results in at least one wire of the lower of the two meshes bisecting each opening in the upper mesh. A third “backing” layer of relatively coarse, mill grade mesh is often used to carry most of the load on the screen and to increase the tensile strength of the screen.
Another problem faced in many applications is the tearing of a screen. The problem can be especially acute in heavy duty applications such as drilling and mining. A torn screen must be replaced or repaired. To facilitate repair, the screen layers are bonded to a rigid or semi-rigid support panel that has a pattern of openings, forming on the screen a plurality of cells of wire mesh. When a tear occurs in the screen, the mesh remaining within the cell in which the tear occurred is cut out and the cell is plugged. The capacity of the screen is diminished but its life is extended. Typically, several cells of a screen can be repaired before its capacity drops far enough to require replacement. Unfortunately, bonding the screen all around the edges defining openings through the support panel further restricts relative movement of the layers and the wires in each mesh layer.
Blinding and tearing of a screen reduce the capacity of the screen continually through its useful life. Although efficiency can be increased by increasing the total area the screens, the size of the screen is limited in most applications, such as on drilling rigs, especially those on offshore platforms. There has thus been generally a trade-off between capacity, longevity, repairability and resistance to blinding of the screens.
There has long been a need, recognized by the present inventors, for a screen assembly with a support which will enhance screen life and repairability with high fluid conductance and flow characteristics. There has long been a need for such a screen assembly which is durable and relatively non-blinding.
SUMMARY OF THE PRESENT INVENTION
A screen according to the present invention has, in certain embodiments, a lower support made of relatively thick wires (e.g., but not limited to between about {fraction (1/32)} inches thick to about {fraction (3/16+L )} inches thick or between about 0.100 inches to about 0.162 inches thick) with flat top surface portions or surfaces of the wires on which additional screening material is placed. In one aspect the majority of the area of all the top portions are in substantially one plane so that screening material placed on the top of the thick wires rests relatively flat. Since the tops of the thick wires are flat—i.e., the majority of the top surface portions or surfaces lie in the same horizonal plane—the screening material emplaced on the thick wires is not worn by points of a non-flat pointed weave pattern and does not assume an undulating shape. In other aspects, the flat wire assumes a relatively flat attitude without the “knuckles” present in many prior art screens. In other aspects according to the present invention, the flat-topped screen or cloth is formed into an undulating shape and then an upper screen or screens on top of the flat-topped screen or cloth assumes a corresponding undulating shape. Flat top wire cloth with such flat top surfaces, known in the prior art, is suitable for the lower support according to the present invention.
In one aspect screening material (any known screen or mesh in any known number of layers connected to and/or adhered to and/or sintered to and/or bonded and/or glued and/or welded together in any known way, or not connected together) is positioned on a lower support according to the present invention on the flat top surfaces of the wire. In certain aspects, the screening material is connected to, adhered to, welded to, glued to, sintered to and/or bonded to (all collectively herein henceforth referred to as “connected to”) the top surfaces of the wires. In embodiments disclosed herein with “screening material” the screening material represents, inter alia, any screening material described above, including but not limited to, a single layer or multiple layers of such material. Flat-topped wire cloth is in some aspects referred to as “smooth top.”
It is, therefore, an object of at least certain preferred embodiments of the present invention to provide:
A new, useful, unique, efficient, nonobvious screen for vibratory separators and shakers;
Such a screen with a lower support made of relatively thick wires with flat top surfaces;
Such a screen with the flat-topped wire cloth substantially in one horizontal plane, or in an undulating shape, and
Methods for making such a screen.
Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods.
The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs. To one skilled in this art who has the benefits of this invention's realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent's object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements.
Adams Thomas C.
Grichar Charles N.
Schulte, Jr. David L.
Seyffert Kenneth W.
McClung Guy
Schlak Daniel K
Tuboscope I/P Inc.
Walsh Donald P.
LandOfFree
Flat top cloth support screen does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flat top cloth support screen, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat top cloth support screen will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445854