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Bernd Küsel, CBG, Germany, examines the significance of high-quality splices and the early detection of injury to make sure security and scale back pricey downtime.
An estimated 100 000 km of metal wire conveyor belts are in use world wide. They’ve been in service for over 80 years as probably the most economical and environmentally pleasant answer for carrying bulk supplies over lengthy distances. Metal wire conveyor belts for inclined shafts, which transport uncooked coal straight and constantly from underground to the floor, are significantly necessary in coal mining (see Determine 1).
As conveyor belts can solely be spliced or made infinite on web site for causes of weight and dimension, they should be transported from the manufacturing facility to the place of use in smaller particular person lengths. The common size of such a single belt is round 300 m. With very high-strength belts, this nonetheless ends in particular person weights of fifty t, and diameters of 4 m. Spherical reels are frequent, however racetrack reels are additionally used.
100 000 km of conveyor belts in use divided by 300 m ends in a complete of over 300 000 splices in use.
Splice geometry
Earlier than the belts could be linked, the suitable splice structure should be decided. This outcomes from the diameter of the ropes and the rope pitch, i.e. the space between the ropes. There should be sufficient rubber between the metal cords within the splice to have the ability to switch the tensile forces. This ends in one to six-step splices. The decrease the belt breaking power, the smaller the variety of phases could be, and the shorter the splice. Because the cable diameter will increase, more room should be created between them, which might solely be achieved by commencement. An ST1000 belt (the quantity after the ST signifies the minimal belt breaking power in Newtons per millimeter of belt width) could be linked in one-step design, and is 0.6 m lengthy, whereas an ST10000 splice has six phases and is greater than 10 m lengthy.
It is very important observe that no rope is straight linked to a different rope. All forces are transmitted by way of the encompassing rubber. This ends in shear forces which, relying on the splice geometry, result in very completely different masses throughout operation.
The final goal is to attain, no less than, the nominal breaking power of the belt statically, in addition to the best potential fatigue power, i.e. dynamic power or Wöhler check, in accordance with DIN 22110.
It is a preview of an article that was initially printed in Problem 1 of World Coal 2025.
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