Patent ID: 7819254
Filing Date: 2010-10-26
Classification: B07B

Abstract:
1. A frame over which woven wire mesh is to be stretched and secured to form a sieving screen which can be used to screen solids from drilling mud recovered from down-hole when drilling for oil or gas comprising: a rectilinear moulded plastics frame having edge regions by which it is secured in place in a shaker and defining a plurality of rectilinear windows formed by an orthogonal array of intersecting ribs also of moulded plastics material wherein some of the ribs are internally reinforced by rigid metal members which extend orthogonally between members which define a rectilinear sub-frame wherein the rectilinear subframe includes members that are internally reinforced by rigid metal having a hollow box cross-section the orthogonal reinforcing members being secured at their ends to the hollow box cross-section members forming the rectilinear subframe and the ends of the latter are joined at the four corners of the sub-frame, so that not only are the edge regions forming the perimeter of the screen frame reinforced, but so also are some of the orthogonally intersecting ribs, so as thereby to produce a rigid frame for the screen, and wherein C-shaped clips are fitted to the box section edge frame members of the sub frame before the latter is inserted into a mould tool, so that the edge members are stood-off from the inside of the mould tool, to permit GRP material to encapsulate the frame members during the moulding process.