Apparatus for scale and slag removal
BACKGROUND OF THE INVENTION 
     Many slag removal systems are known. However, the present system prevents jamming and feed rate problems and does an excellent job of slag removal. 
     The closest known prior art includes a machine in which the conveyor travels over a back plate which is suspended on air bags, but in which the remainder of the conveyor is not so suspended. With such a bed plate, changes in the location of the bed plate cause changes in the length of the conveyor and stretch the belt. 
     There is also a known machine in which the entire sanding belt, with its supports and its drive motor, is pivoted at the center and biased by a pneumatic cylinder toward the work piece. It is very difficult to maintain the unit stable and parallel to the work piece to give a smooth surface. Moreover, the large rotating mass is a problem and the entire machine is unnecessarily complicated. 
     SUMMARY OF THE INVENTION 
     The invention here consists of mounting a conveyor for steel slabs on a parallelogram linkage in which the links of the parallelogram are inclined toward the incoming material and the conveyor is upwardly biased to bring the material on the conveyor belt into contact with the fixed surfacing device above it. Preferably the bias is supplied by air bags and preferably the entire conveyor is mounted on the parallelogram linkage rather than just a part of it. 
     By so mounting the conveyor, the entire conveyor can move downwardly, and toward the input side, when the incoming work pieces such as metal slabs are higher than the distance between the conveyor and the surfacing unit, while maintaining an elastic upward bias toward the surfacing unit. Because the movement of the conveyor downward is also a movement away from the surfacing unit, this tends to relieve the load on the surfacing unit and prevent jamming by slightly decreasing the feed rate. If the links were inclined in the other direction, so that downward movement of the conveyor would bring the work piece toward the surfacing unit, that would tend to produce too great a feed rate and would tend to jam the machine. 
    
    
     DRAWINGS 
     FIG. 1 is a side view of the surfacing conveyor of my device. 
     FIG. 2 is a view similar to FIG. 1 in which the surfacing of a steel slab is partly accomplished. 
     FIG. 3 is a perspective view showing the overall appearance of my device. 
     FIG. 4 is a cross sectional view on line 4--4 of FIG. 1 showing details of the parallelogram linkage. 
    
    
     DESCRIPTION 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the best known embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     As shown in the drawings, the preferred form of my invention includes an abrasive sanding device 10 including rolls 11 and 12 and an abrasive belt 13. These, together with other conventional structure (not shown) are supported at a fixed height from a base 14. 
     A conveyor 20 including a belt 21, end rolls 22 and 23, a bed plate 24, and other conventional structure (not shown) to drive the belt 21, so that as shown in FIG. 1, a work piece 25 is driven to the left in the direction of the arrow. A pair of links 26 at each side of conveyor 20 are pivoted at 27 to the fixed base 14 and pivoted at 28 to the side plates 29 of conveyor 20. The links 26 are inclined so that the upper ends and pivots 28 are closer to the direction from which the work piece is coming than the lower ends and pivots 27. 
     The entire conveyor 20 is biased upwardly toward the fixed abrasive sander 10. In the preferred form of my device the upward bias is provided by pneumatic bags 30 operating between brackets 31 attached to base 14 and 32 attached to conveyor 20. Each bracket includes a horizontal plate, between which bag 30 acts. Upward movement of conveyor 20 is limited by a stop means, here shown as a bar 33 secured to the conveyor side plate 29 and a plate 34 secured to base 14 and having a flange 35 overlying bar 33. Downward movement of conveyor 20 is limited by air bags 30 and supporting brackets 31 and 32. During operation the air bags 30 are inflated to a level which supports conveyor 20 at the desired distance from abrasive belt 13 to surface the work piece as shown in FIG. 2. 
     Because conveyor 20 and bed plate 24 are supported by air bags 30 in such a manner that the conveyor can move around the pivots 27 and 28 of parallel links 26, a thick section of the work piece, such as slag, causes the conveyor not only to move downwardly, but to back off slightly because of the angle of links 26, thus preventing jamming but maintaining firm contact between abrasive belt 13 and work piece 25 in order to continue to surface the work piece without jamming. Because the sanding belt 13 is in fixed position with respect to the base and the entire conveyor 20 moves on parallel links, the abrasive belt continues to remove slag and unwanted material regardless of dimensional variations. The very slight decrease in feed rate that results from movement of the conveyor downwardly and backwardly with respect to the feed direction when the edge of the work piece or a higher portion of the work piece comes in contact with the abrasive belt 13 is an important advantage. 
     Likewise, it is preferred that the entire conveyor, rather than merely the bed plate, be suspended in order to avoid changes in the length of the conveyor belt which adversely affect the performance of the conveyor.