Patent ID: 7716834

Claim:
A method for manufacturing a screen, characterized in that said screen comprises a base pipe with multiple penetrated holes on pipe wall, a filter sheath and a jacket with multiple holes; wherein the filter sheath is placed on and covers the outside of the base pipe and the jacket is placed on and covers the outside of the filter sheath, and the welding method comprises the steps: step 1: wrapping the outside wall of a support sheath with a metal filter net and fixing the metal filter net to the outside of the support sheath by way of resistance welding, such that the metal filter net completely covers all penetrated holes of the support sheath to form the filter sheath; step 2: fixing said filter sheath to the outside wall of the base pipe and the filter sheath completely covering all penetrated holes of the base pipe; step 3: putting said jacket round the outside of the filter sheath and fixing it to the outside of the base pipe, such that said jacket completely covers the outside surface of filter potion of the filter sheath; wherein said step 1 comprises: step 1a: fixing one end of the metal filter net to the outside wall of the support sheath along axial direction of the support sheath by way of spot welding; step 1b: wrapping the outside wall of the support sheath with the metal filter to completely cover all penetrated holes on the support sheath; step 1c: welding the metal filter net which wraps the outside wall of the support sheath to the support sheath along axial direction of the support sheath; step 1d: welding the ends of the metal filter net which wraps and covers the ends of the outside wall of the support sheath to form the filter sheath; wherein welding the ends of the metal filter net in step 1d comprises: providing an inner welding head inside the filter sheath and an outer welding head outside the filter sheath pressing against each other at the same end of the filter sheath, so that the support sheath and the metal filter net are tightly pressed against each other at weld points; supplying instant welding current by the inner welding head and the outer welding head, the parts of the support sheath and the metal filter net, which conduct the welding current, are welded in a whole at the weld points by way of electric arc welding; separating the inner welding head and the outer welding head from the filter sheath, and rotating the inner welding head, the outer welding head or the filter sheath around the axis of the filter sheath so as to locate the inner welding head and the outer welding head to next un-welded position; repeating the above welding procedure till the welding of the metal filter net which covers the support sheath is finished along the circular outside of the end of the support sheath.