Innovative design of a longwall shearer's haulage system with highly loaded components of a tribological pair manufactured according to the precise casting technology

摘要

Increased wear of drive wheel teeth in a longwall shearer requires frequent replacement of this expensive component, due to use of high power drives and geometrical limitations to the advance systems. A concept of the innovative Flextrack advance system, which enables limiting the high pressing stresses between cooperating surfaces of drive wheel and tooth gear (according to Hertz), was developed. The tooth gear, which consists of single segments, each with only one tooth, is the main component of Flextrack advance system. The sidewalls of the tooth gear have tacks of spherical shape located on the surfaces of the segments cooperating with each other. This design causes that the segments can be "seated" against each other, with no need to change the pitch between the teeth. The surfaces of tracks of tooth gear segments can incline transversely and longitudinally, and it is limited only by a special guide. The advance tooth gear system made in such way enables one to overcome horizontal and vertical inclinations of the conveyor route on which the shearer moves. The material model accepted for numerical analyses assumed the use of high strength spheroidal cast iron EN-GJS-1200-2 and L20HGSNM cast steel. The manufacture of casts of tooth gear segments in a precise casting technology enables one to obtain high accuracy of cooperating spherical surfaces as well as surfaces of the flank of the tooth cooperating with drive wheel. Accepted casting technology ensures high repeatability and the reduction of the cost of a single tooth gear segment, assuming serial manufacture. Changes applied to the design of advance system will increase the operational life of drive wheels, significantly reducing the maintenance time in very dangerous conditions.