Classifying – separating – and assorting solids – Sifting – Elements
Reexamination Certificate
1999-05-24
2001-08-07
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Elements
C209S403000, C209S311000, C209S309000
Reexamination Certificate
active
06269954
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a seal for adjoining screens used with vibrating machinery. In particular, the present invention is directed to a seal for screen assemblies wherein the seal prevents leakage of fluid between adjoining screen assemblies.
2. Prior Art
Vibrating shakers utilize a screen assembly or a plurality of screen assemblies to separate solid material from liquids and fine solid particles. The screen assembly is typically secured in and to the vibrating machinery through use of a frame. In some cases, a single screen assembly will be utilized while in other cases, a plurality of screen assemblies will be aligned adjacent end-to-end each other. The screen assembly is removably attached to the vibrating shaker. A mixture of materials is delivered or fed to the top of the screen assembly. The screen assembly is vibrated by a motor at a high frequency.
The force of gravity separates the liquid from particles larger than the pore size made up by the combination of layers. This pore size is called the “cut point.” The screen assembly may be inclined when secured in the vibrating shaker so that the solids larger than the cut point will move across the screen where they are gathered and disposed of. In other arrangements, one screen assembly is oriented in the shaker in angular relation to the other screen assembly. In each case, the liquid and particles smaller than the cut point pass through the screen assembly and are also collected.
Vibrating shaker machines are often used at remote locations, such as oil and gas well drilling sites. The replacement screen assemblies must, thus, be transported great distances to these remote locations. A relatively lightweight screen assembly is therefore desirable.
Since the screen assembly must be transported and then installed in the field, any sharp edges on the screen assembly should be minimized.
There are various types of screen assemblies having various frames. In one configuration, a plurality of screen cloth layers are attached to a perforated plate which is, in turn, connected to the frame. The perforated plate has a large number of small openings to minimize the unsupported spans of screen cloth. It is important to achieve good adhesion between the perforated plate and the frame. Thus, the frame must have an adequate planar surface to attach securely to the perforated plate.
The screen assembly is subject to tremendous stresses caused by the machinery vibrating it. Additionally, the screen assembly is subject to stresses from the weight of the material to be separated on the top layer of the screen. It is known that the screen assemblies will wear from usage and have a certain useful life, often in hours.
In order to balance screen life with through-put, it has been known to secure multiple layers of wire screen cloth to a perforated panel. The perforated panel is, in turn, secured to the frame. In the manufacturing process, the perforated panel and accompanying screens must be accurately aligned before adhesively bonding to the frame. It would be desirable to provide a self-alignment mechanism to align the perforated plate with the frame.
One problem with existing screen assemblies is that they permit a mixture of liquid and solid particles to flow between adjoining screen frames, thereby allowing the liquid to bypass and frustrate the process described above for separating the mixture into liquid and solid particles.
It is a principal object and purpose of the present invention to prevent leakage of a mixture of liquid and solid particles between adjoining screen assemblies.
It is a principal object and purpose of the present invention to prevent leakage of a mixture of liquid and solid particles between a screen assembly and the vibrating machinery.
It is a further object and purpose of the present invention to provide a replaceable screen assembly for a vibrating shaker that is simple and quick to install and replace.
It is a further object and purpose of the present invention to provide a screen assembly with a seal that will have a maximum useful life while being simple and inexpensive to manufacture.
It is another object and purpose of the present invention to provide a screen assembly having a frame which will position the perforated panel thereon during the assembly process and discourage separation of the frame from the perforated panel.
It is a further object and purpose of the present invention to provide a screen assembly having a strong frame which will provide strength from side to side and provide strength from end to end.
SUMMARY OF THE INVENTION
The present invention is directed to a seal for adjoining screen assemblies having a frame, where the screen assemblies are secured to and used with vibrating machinery. The frame includes a pair of opposed sides, a first opposed end, and a second opposed end. Each opposed side, the first opposed end and the second opposed end have flat planar surfaces. At the first opposed end, a seal shoulder is on top of the first opposed end planar surface. At the second opposed end, an end stop is attached to the frame beneath the planar surface. The seal shoulder of one screen assembly engages the end of another screen assembly to form a seal to prevent liquids from leaking between the two adjoining screens.
In one embodiment of the invention, each opposed side of the frame includes a leg which extends downward perpendicular to the planar surface. Ledges extend perpendicular to the downward legs. The ledges are opposed to each other. The frame also includes a plurality of tubular cross supports which extend between the sides and are parallel to the ends. The tubular cross supports rest on and are attached to the ledges.
A perforated plate is attached and secured to the frame in the assembled condition. The perforated plate includes a plurality of openings which are punched or otherwise formed in the plate. The frame is adhesively secured to the perforated plate. The plate and the accompanying screen cloths are aligned on the frame by the lips which form a rim enclosure.
In order to produce a screen assembly in accordance with the present invention, the sides and ends of the frame are extruded in lengths, such as from extruded aluminum. The frame sections are cut to desired lengths to form the pair of opposed sides and the pair of opposed ends. The sides and ends are cut at 45° angles so that they will mate together to form an exterior frame.
Likewise, lengths of tubular support are extruded, such as from extruded aluminum. Tubular support members are cut from these lengths to the desired dimension. The opposed sides and the opposed ends are clamped together and then tack welded. Thereafter, the entire frame, including the cross supports, is welded together. The joints between the cross supports and the sides of the frame are strengthened since the cross supports rest on the ledges.
The perforated plate is fabricated with hexagonal or other openings and, thereafter, coated with epoxy. Both heat and pressure are used to bond the multiple screen mesh layers to the perforated plate. Accordingly, the perforated plate and the screen cloths are secured together. Thereafter, the perforated plate and the accompanying screen cloths are secured to the frame by glue or other adhesives. The lips form a rim enclosure that aligns the perforated plate and accompanying screen cloths on the frame. The plate is prevented from moving from side to side or end to end with respect to the frame because of the rim enclosure. The lip also provides a blunt, safe edge around the perimeter of the screen assembly which keeps personnel from cutting their hands.
REFERENCES:
patent: 1009069 (1911-11-01), Hunnicutt
patent: 1147279 (1915-07-01), Sweetland
patent: 2271900 (1942-02-01), Mowbray
patent: 2335084 (1943-11-01), Rice
patent: 2576794 (1951-11-01), Jost et al.
patent: 2870910 (1959-01-01), Wehner
patent: 2902165 (1959-09-01), Imershein
patent: 2959285 (1960-11-01), Tonjes et al.
patent: 3012674 (1961-12-01), Hoppe
patent: 3508649 (197
Beauchaine Mark J.
Head Johnson & Kachigian
Southwestern Wire Cloth, Inc.
Walsh Donald P.
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