Analysis of reason causes belt conveyor pulley lagging abrasion, its improvement measures and repair methods
Analysis of reason:
The pulley lagging is partially damaged during operation, mainly due to the following reasons:
(1)The rubber material is out of date or contains impurities, resulting in insufficient adhesion between the rubber layer and the pulley, or low strength of the rubber laye which will be easily deformed or damaged after being stressed.
(2) The wear caused by coal dust and dirt on the pulley surface are the typical abrasion reasons. Due to the chemical action of the liquid or gaseous medium, especially the action of high temperature, the abrasion is aggravated and the strength of the pulley is reduced.(3) The influence of the wrapping angle on wear: Increasing the wrapping angle will increase the traction on the surface of the pulley and reduce the abrasion, but the wrapping angle can not be too large, otherwise it will increase the bending fatigue damage of the belt.(4) Poor rubber splashing or casting process, such as poor vulcanization temperature control will result in poor repair quality, local rubber layer damage or degumming.(5) Due to the belt deviation during use, the adhesive layer is locally unevenly stressed or scratched by foreign matter, causing local damage. The pulley runs for a long time, and fatigue damage is also the cause of cracking or damage to the adhesive layer. The above reasons make the rubber layer of the pulley partially uneven, which reduces the friction of the belt on the pulley, and makes the belt slip during operation. The uneven force causes the belt to appear deviation that is not easy to adjust during operation.
Improvement measures:
Generally, when the above situation occurs, the most traditional solutions are using bead welding, thermal spraying and brushing electroplating. But they all have great disadvantages. Such as bead welding, it will lead to a huge heat during the process,the thermal stress caused by this heat will leads to damage, bending, deformation, and fracture of the conveyor in the future operation. The brushing electroplating is limited by the thickness, and it is easier to peel off in the later stage. Practice has proved that these two methods can solve the problems of pulley lagging, but they will correspondingly leave sequelae to the conveyor line. Increasing the coefficient of friction is the best way to reduce wear. At present, people are trying to find materials with high friction coefficient, stable performance, abrasion resistance and good endurance for pulley liners.
Below we introduce a method of rubber repair,hoping to provide technical reference for the corresponding repair work.The formula mainly includes epoxy resin,polyurethane flame-retardant repair adhesive,ethylenediamine and maleamide,etc.Blend the two-component polyurethane flame-retardant repair adhesive with a ratio of 60:40 to maleic acid amine,and then blend the two-component epoxy resin and ethylenediamine with a ratio of 96:4 .The ratio of the above two blends is 85:15.Many tests have proved that this adhesive set not only has adhesion to steel but also rubber.
The repair process is as follows:
(1)Clean the damaged parts and remove the coal dirt,mud and other impurities;(2)Use a knife to cut off the leftover material and cut into a slope surface;(3)Use a grinder to polish the rubber layer and the damaged part,Expose the surface of the damaged pulley part.Remove the rust on the surface of the pulley, and clean up the rubber repair surface with a brush;(4)Clean the polished damaged area with gasoline, and remove oil and impurities;(5)Pour the polyurethane flame retardant repair rubber component B into component A, stir evenly,and then blend with maleic acid amine within 1 min according to the ratio.(6)Mix the two liquids until they are uniform, and then reconcile them with ethylenediamine according to the ratio;(7)Reconcile the above-mentioned two rubber materials according to the ratio,and then apply them to the damaged area with a thickness of about 2mm.(8)Finally,pour the evenly mixed A and B two-component polyurethane flame-retardant repair glue into the damaged area to make it the same thickness as the original rubber layer, and smooth it with a scraper.
