Patent Publication Number: US-4321068-A

Title: Non-welded discharge electrode

Description:
This invention relates to mast discharge electrodes as used in electro-precipitators. 
     Mast discharge electrodes are used in electro-precipitators in rows between rows of dust collector electrode plate members, the plate members being earthed and the discharge electrodes being charged to a high potential to deposit on the plate members dust from gas flowing between the rows. The mast discharge electrodes may be up to 45 ft. in length and generally extend transversely to the direction of gas flow, i.e. they extend vertically, and, for mechanical strength, may typically take the form of a central tube and parallel wires spaced from the tube on horizontal spacer bars. During construction the tube is drilled to take the spacer bars which are also drilled to take the wires and the whole assembly is welded together, i.e. bars to the tube and wires to the bar. 
     Not only is such a construction expensive but also difficulties arise in proper alignment of the component parts, in weakening of the wires because of the welding and in distortion arising from the heat of welding. 
     It is an object of the present invention to obviate or mitigate these difficulties. 
     The present invention is a method of making a mast discharge electrode comprising forming transverse holes through a tube, inserting cross members in said holes and securing the members in said holes, passing at least two wires through holes in said cross members to extend parallel to said tube, and securing said wires by friction in the holes in the cross members. 
     The present invention is also a mast discharge electrode comprising a tube having holes passing transversely therethrough, cross members secured in said holes, at least two wires extending parallel to said tube and passing through holes in said cross members, said wires being secured in said holes by friction. 
    
    
     Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: 
     FIG. 1 illustrates a mast discharge electrode according to the present invention; 
     FIG. 2 is a section on the line II--II of FIG. 1; 
     FIG. 3 is a section on the line III--III of FIG. 2; and 
     FIG. 4 is a view in the direction of the arrow IV of FIG. 3. 
    
    
     As indicated in FIG. 1, a mast discharge electrode 10 comprises a vertical central tube 11 from which extend vertically spaced, horizontally extending cross members 12 which in turn support one or more pairs of fabrication wires 13 spaced by the cross members 12 from the tube. The central tube 11 is, in this embodiment, a mild steel continuously welded seamed tube. 
     The cross members 12 are located in position in holes 15 (see FIG. 2) which have been formed in the tube from each side. 
     Each cross member 12 is provided with raised knurled central portion 16 so that as each cross member is pushed into the holes 15 in the tube, the raised knurled portion 16 engages and bites the edges of the holes and is gripped thereby. This frictional engagement of the cross members 12 in the holes 15 has been found to be perfectly satisfactory, but it is preferred to form the holes 15 by a punching operation, as in the embodiment illustrated, rather than by a drilling operation thereby to increase the area round the hole engaged by the cross member and to take advantage of the natural &#34;C&#34; spring formed by the material. 
     Each cross member 12 is provided with holes 20 for the wires 13 and it is preferred to form these holes by drilling. In this embodiment the cross members 12 are also tubular and the wires 13 are secured in position in the holes 20 by crimping the tube to bring the edges of the holes into engagement with the wires and so secure the wires in position by friction. 
     The top cross member is provided with a second set of holes adjacent the holes 20, the top of each wire 13 being formed into a &#34;U&#34; shaped return and secured in a respective one of the second set of holes. 
     As illustrated in FIGS. 3 and 4, the crimping operation has had the effect of moving a portion of the circular side wall of the cross member from its circumferential position to that of a chord, but any suitable form of crimping may be used. 
     In a modified embodiment of the invention the cross members 12 are rods, but again the wires 13 are secured in holes in the cross members by a crimping operation. 
     Alternative crimping operations may be used which either simply squash the cross member onto the wire or which produce a crimp in a direction perpendicular to the wire axis to secure the wire. 
     In a further modified embodiment the wires are secured in the holes in the cross members by inserting a member into the hole around the wire to wedge the wire peripherally into the hole. 
     The wires 13 used in the embodiments described are of square cross-section and twisted, and are preferably made of mild or stainless steel. 
     The tube 11 and cross members 12 may be made of aluminium or stainless steel, and in these cases the invention is particularly useful in view of the difficulties of welding these materials. However, the cross members may be welded to the tube if desired.