| 摘要 |
A method is described for making a reinforcing wire frame for embedding in a moulded polymer support frame (10) over which woven wire cloth (158,159) is to be stretched and secured to form a sifting screen. The method involves locating lengths of cut wire (50) substantially equally spaced apart in a jig to form a first array. A second array of lengths of cut wire (56,60) is located over the first array with the lengths of wire in the second array being substantially at right angles to those of the first array. The lengths of wire in the first and second arrays are resistance welded at points of mutual intersection so as to form a first substantially rectilinear matrix. Lengths of cut wire (48) are located in a jig to form a third array, in which the lengths are also substantially equally spaced apart, and a fourth array of lengths of cut wire (54,58,62,64) is arranged over the third array with the lengths of the fourth array substantially at right angles to the lengths of wire of the third array, and the wires of the third and fourth arrays are also resistance welded at points of mutual intersection to form a second substantially rectilinear matrix. Protruding lengths of wire on at least two sides of the four sides of one of the rectilinear matrices are bent using a press so as to bend each protruding length first in a generally upward sense and then at a point nearer its end in a generally downward sense so that an end region of each protruding length extends parallel to a plane of the matrix but is displaced therefrom. Thereafter the displaced ends of the protruding lengths of wire of one matrix are resistance welded to protruding lengths of wire of the other matrix, to form the frame. <IMAGE> |
