Coating processes – Coating remains adhesive or is intended to be made adhesive
Reexamination Certificate
2001-10-19
2003-12-30
Pianalto, Bernard (Department: 1762)
Coating processes
Coating remains adhesive or is intended to be made adhesive
C427S208200, C427S420000, C427S428010, C427S430100
Reexamination Certificate
active
06669985
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to glued screens for vibratory separator apparatuses and shale shakers; to methods for making such screens; to automated methods for making such screens; to screens made by such methods; to machines for making such screens, and to vibratory separator apparatuses and shale shakers with such screens.
2. Description of Related Art
The need for solids control in drilling mud used in hydrocarbon well drilling is well known in the prior art. Drilling mud, typically a mixture of clay and water and various additives, is pumped down through a hollow drill string (pipe, drill collar, bit, etc.) into a well being drilled and exits through holes in a drillbit. The mud picks up cuttings (rock) and other solids from the well and carries them upwardly away from the bit and out of the well in a space between the well walls and the drill string. At the top of the well, the solids-laden mud is discharged over a shale shaker, a device which typically has a series of screens arranged in tiered or flat disposition with respect to each other.
The prior art discloses a wide variety of vibrating screens, devices which use them, shale shakers, and screens for shale shakers. The screens catch and remove solids from the mud as the mud passes through them. If drilled solids are not removed from the mud used during the drilling operation, recirculation of the drilled solids can create weight, viscosity, and gel problems in the mud, as well as increasing wear on mud pumps and other mechanical equipment used for drilling.
SUMMARY OF THE PRESENT INVENTION
The present invention discloses, in at least certain aspects, methods for making screen assemblies for vibratory separators and shale shakers, the method including applying glue in a glue pattern to at least one layer of screening material useful for screening fluid introduced to a vibratory separator or shale shaker, the applying done by powered moving mechanical glue application apparatus; and, in one aspect, the glue is heated moisture-curing hot melt glue. Such methods may also include applying moisture to glue in a glue pattern following application of moisture-curing hot melt glue to layer(s) of screening material.
The present invention discloses, in at least certain embodiments, methods for making a screen or screen assembly for a vibratory separator or shale shaker, the method including: moving with screen movement apparatus at least one layer of screening material below a glue application apparatus, the glue application apparatus including a main body and a plurality of movable glue nozzles movably connected to the main body; moving the movable glue nozzles with nozzle movement apparatus above the at least one layer of screening material; applying with the movable glue nozzles an amount of glue flowing from the glue nozzles in a pattern to at least a portion of the at least one layer of screening material, and allowing the glue to cure.
In certain aspects the present invention provides a method and machines for making a glued-together combination of two, three or more layers of screening material. In certain aspects the thus-produced combination is suitable for use in screen assemblies used on shale shakers, with or without screen assembly lower support structure or apparatus for the screening material layer(s).
The present inventors have recognized that: a first layer of screening material moved beneath glue applying nozzles that apply a desired glue pattern is, preferably, stabilized and/or held in tension relatively tight and flat as it moves beneath the glue nozzle(s), to inhibit vibration of it, and to facilitate the application of a uniform glue pattern of uniform glue bead thickness across a major part of or over substantially all of the surface of the screening material; moisture-cure hot-melt glue is, in certain aspects, cured more quickly by applying water to the glue before and/or while it cures than by air exposure, before removing the screen combination from a machine, before rolling the thus-produced screen combination up on a roll, and/or before setting it aside for glue curing by air exposure; hot-melt molten glue is used, preferably, which does not pass quickly through layer(s) of screening material to which it is being applied due to its viscosity; hot-melt molten glue can be moved up from a lower layer to which it is initially applied (e.g., but not limited to a relatively coarse layer such as 14-25 mesh), e.g., by heating the screen combination, e.g., by blowing heated air on it or by passing the screen combination beneath a heated top roller or through a pair of opposed rollers with the top roller of the pair heated, thus heating the top layer(s) of screening material to facilitate the gluing together of multiple layers, e.g. heating to at least about seventy degrees F. and preferably between seventy degrees F. and two hundred fifty degrees F., with about one hundred degrees used in one embodiment; to facilitate the curing of the glue by cooling it, e.g., by cooling a roller beneath the screen combination or by cooling a lower roller of the roller pair referred to above and/or by blowing cool air on the curing glue; plastic coating on a roller inhibits the sticking of glue to the roller, e.g., but not limited to applying polytetrafluoroethylene sheets, fabric, pieces, or tape (smooth or textured) to a roller; using such a tape, sheet, piece, fabric etc. that has a texture, pattern, or projecting parts or portions imparts a corresponding texture, etc. to glue on the screen combination that comes in contact with the texture, etc. and that such a resulting texture, etc. formed in the glue is advantageous because it enhances contact between the glue and screening material, provides structure that “grabs” the screening material thus facilitating its passage through the rolls, and inhibits channeling down a glue line; and that rolls of glued-together screen combination can be produced which are relatively long as compared to the length of a single shale shaker screen assembly, e.g., but not limited to at least twenty, one hundred, two hundred, four hundred, six hundred, or eight hundred foot long rolls—which in certain aspects are rolled up with a release layer or liner, or a separator which, in certain aspects, is kraft paper silicone coated on both sides. This inhibits or prevents parts of the glued screening material from adhering to each other as glue cures.
The screening material fed through such machines may be any desired dimensions, including, but not limited to, dimensions corresponding to the typical lengths or widths typically used to make known screens for shale shakers. PUR hot melt glue, e.g., but not limited to, commercially available Henkel R 183 B Glue from the Henkel Co. or similar glues may be used.
In certain aspects, using a “nip” or dual opposed rollers (optionally under pressure) between which multiple screen layers being glued together are passed, glue moves and/or is squeezed upwardly between mesh in the screening layers. In one aspect a bottom nip roller (in one embodiment coated with a non-stick substance or tape) pushes up against a lower surface of a bottommost screen layer, preventing glue from moving down and out from the screen layer. Optionally, such a bottom roller may be cooled (by any known method and/or device or apparatus, including but not limited to, those disclosed or referred to herein), thus increasing the viscosity of at least lower portions, if not a large portion of the glue and inhibiting downward travel of the glue. The wires or strands of the mesh(es) restrict side-to-side glue movement and the glue, therefore, can only travel up into layers above a layer or layers to which the glue was initially applied. Optionally, the top roller is heated by any known method and/or device or apparatus (including, but not limited to, any disclosed or referred to herein), which heats upper parts and/or layers of mesh(es) which results in the heating of upper portions of glue that has been applied to one or more la
Adams Thomas C.
Grichar Charles N.
Largent David W.
Leone Vincent D.
McClung, III Guy L.
McClung Guy
Pianalto Bernard
Varco I/P Inc.
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