When the roll shell of the roll crusher is worn, the surface of the roll skin is not cylindrical, and a concave profile with two large heads and a small middle is formed. At this time, the larger block or the mud group may pass through the worn notch, and the crushing effect is not obtained, so the roll skin should be repaired regularly. There are two methods for roll shell repair: in-situ cutting (grinding) machining repair and in-situ overlay welding repair.
1. In-situ cutting (grinding) processing method. The method of in-situ machining is to install a special tool holder on the frame of the roller crusher, the path of which should be parallel to the axis of the roll shell. The crusher is started at the time of repair, and the roll shell is cut by a manual feed mechanism (conditional automatic feed mechanism is also available). The following points should be noted when applying this method: 1 The trajectory of the tool holder is parallel to the axis of the roll skin to avoid taper after cutting and affect the crushing effect. 2 Control the speed of movement of the roll shell. The line speed on the surface of the roll should not exceed the allowable cutting speed of the cutting tool. Otherwise, speed reduction measures should be taken to avoid damage to the tool. 3 For high-hardness roll skin, the cutting cannot be processed. In this case, the grinding head can be ground by the cutting method.
2. On-site surfacing method. In-situ overlay welding is the welding fill at the worn notch. This method is simple and practical, does not affect the production, and the hardness and wear resistance of the surfacing part are relatively good. The disadvantage is that it is only suitable for the roll skin with good weldability (such as cast steel roll shell). Pay attention to the following matters during surfacing: 1 The selection of the surfacing electrode should be appropriate, and D256 and D266 should be used. 2 should choose small-diameter welding electrode, small current welding specification, layered surfacing. This reduces thermal stress and avoids severe deformation and cracking. 3 During the surfacing process, it is necessary to economically check the surfacing parts with a straight-line model to ensure the proper size. 4 The welding machine's grounding should be placed directly on the roll shell, not on the shaft, so as to prevent current from flowing through the rolling bearing to generate sparks, so that the bearing rolling elements and the surface of the raceway are burnt.
In addition, it is also possible to use the post-removal repair method, which is to completely remove the roll shell shaft together, and then repair it to the machine for installation.
