Dummy bar for continuous casting machines
FIELD OF INVENTION 
     The invention relates generally to dummy bars for continuous casting machines having an at least partially arc-shaped strand guide whereby on both sides of a flexible metal sheet several rows of contact elements are fastened over a portion of their length and free projections of these contact elements along different rows overlap in a direction longitudinal of the dummy bars. 
     BACKGROUND OF THE INVENTION 
     In known dummy bars such as that described in DE-OS 28 09 844, several rows of contact elements are arranged in a staggered distribution next to one another on a flexible sheet of metal. The contact elements have a trapezoidal shape or are skewed to form a bend-free area of overlap and are attached to the sheet metal surface with a small attachment surface. 
     This prior art dummy bar has the following disadvantages: the metal sheet is only freely bendable in the narrow overlapping areas, and in these areas, notch tensions occur. For this reason the dummy bar is not suited to strand guides with a small radius of curvature. With each contact of the driven rollers of the strand guide with an overlapping region, an overturning moment occurs because of the smaller attachment surfaces of the contact elements which puts too severe a load on their points of attachment. 
     It is one object of the invention to create a simple, operationally safe dummy bar which is especially suited for continuous casting machines for thin steel strips with a small radius of curvature. 
     Another object of the invention is to avoid overturning moments in the contact elements and notch tensions. 
     SUMMARY OF THE INVENTION 
     For dummy bars of this type, these and other objects are achieved according to this invention by providing the flexible sheet with holes corresponding to the free projections. 
     Alternatively, the objects of the invention are achieved by providing the dummy bar with several flexible sheet metal strips arranged in spaced relation next to one another. These strips are connected by cross-pieces and pieces with free projections of the contact elements are located in the space between the sheet metal strips. 
     The dummy bar according to this invention can be manufactured cheaply and is of low maintenance. Operational safety is improved because overturning moments and notch tensions are avoided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects, advantages and features of this invention will be more clearly appreciated from the following detailed description when taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a partial view of a dummy bar of this invention with rectangular contact elements; 
     FIG. 2 is an enlarged longitudinal section taken along the line II--II of FIG. 1; 
     FIG. 3 is a partial view of a dummy bar of this invention made from several sheet metal strips; and 
     FIG. 4 is an enlarged longitudinal view taken along the line IV--IV of FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Dummy bar 1 shown in FIGS. 1 and 2 comprises a flexible sheet 2, preferably made of spring steel, at the end of which is attached a dummy bar head 3 for sealing a continuous casting mold and for forming a connection with the cast strip. Sheet 2 is fastened to dummy bar head 3 at slit 3a of dummy bar head 3. 
     Recesses 4, 5, 6 and 7 are disposed in flexible sheet 2 and are arranged in four rows extending in a longitudinal direction with respect to the casting direction, in which each two neighboring rows of the recesses 4, 5, 6 and 7 are staggered in a longitudinal direction with respect to the rows adjacent thereto. Rectangular contact elements 8 are disposed between the recesses on each side of sheet 2 and elements 8 are fastened with rivets 9 and extend over the recesses 4, 5, 6 and 7 with projections 10 which are supported by shims 11. The staggered arrangement of contact elements 8 results in an overlap of their associated projections 10 so that as dummy bar 1 passes through the strand guide of the continuous casting machine, dummy bar 1 forms a contact path for the strand guide rollers (not shown) which is free of holes and therefore smooth. Projections 10a disposed on dummy bar head 3 provide a transition to dummy bar head 3. 
     The contact-free guiding of the projections 10, 10a within the recesses 4, 5, 6 and 7 provides a good fit for dummy bar 1 even within a strand guide which has a small radius of curvature. Dummy bar 1 is also usable in a continuous casting machine employing a strand bending system. 
     An alternative embodiment of the dummy bar of this invention is shown in FIGS. 3 and 4. Dummy bar 12 comprises five flexible strips 13, 14, 15, 16 and 17 arranged in spaced relation next to one another. Strips 13-17 are preferably made of spring steel. Strips 13-17 have been inserted into a slit 18a of a dummy bar head 18 and fastened thereto. 
     Strips 13, 14, 15, 16 and 17 are connected on each lateral side by cross pieces 19a and 20a of respective contact elements 19 and 20 which are fastened to strips 13-17 by rivets 21. Elements 19 and 20 each have two longitudinal pieces 19b and 20b respectively. Longitudinal pieces 19b and 20b of respective elements 19 and 20 extend into respective spaces 22 and 23 between strips 13-17. Thus, longitudinal pieces 19b and 20b of adjacent contact elements 19 and 20 overlap in a longitudinal direction in the alternating spaces 22 and 23. Shims 24 are disposed between the two portions of contact elements 19 and 20 which are between the respective longitudinal pieces 19b and 20b. 
     On the mounting side of dummy bar head 18 there are disposed projections 25 to assure a smooth transition. 
     The inexpensive dummy bar 12 formed in such a way can be transported evenly and smoothly by the strand guide rollers (not shown), whereby good adaptation to small radii of curvature of the strand guide as well as to small bend radii are possible. 
     Having described preferred embodiments of the present invention, it should be obvious to those skilled in the art that various modifications and alterations are possible without the departing from the scope of the invention. Such obvious modifications and alterations are intended to be included within the scope of the invention which is not to be limited by the above discussion of the preferred embodiments. The only limitations upon the scope of the invention are defined by the appended claims and their equivalents.