1. The rollers form a groove angle.
Bearing branch usually adopts groove-shaped roller group consisting of three sections of rollers, and the angle between its side roller and middle roller is called groove angle. Within a certain limit, the larger the groove forming angle, the greater the material flow. However, when the groove forming angle exceeds the groove forming capacity of the conveyor belt, the conveyor belt will not closely contact the middle idler during no-load operation, resulting in strong wear and unstable operation of the conveyor belt edge; during heavy-load operation, the conveyor belt At the corner of the side idler roller and the middle idler roller, a large bending stress is inevitably generated, which causes the conveyor belt to longitudinally break or the canvas layer to peel off quickly. Therefore, the design requires that the idler groove angle must be consistent with the groove capacity of the selected conveyor belt, and this principle should also be observed when replacing a new conveyor belt in use. Generally, the idler roll angle is 30. When the conveyor belt has good groove performance, it can be increased to 35.
2. Excessive distance.
The conveyor belt section between the head and tail rollers of the conveyor and the first set of supporting rollers is called a transition section. In the transition section, the conveyor belt changes from groove shape to parallel or from parallel to groove shape, and the edge of the conveyor belt is stretched to produce additional tensile stress. The smaller the length of the transition section, the greater the additional tensile stress, which causes serious wear on the edge of the conveyor belt and the side rollers, thereby causing premature fatigue of the conveyor belt and even causing the edge of the conveyor belt to break. In order to make the edge of the conveyor belt partially extend not to exceed the elongation rate of the conveyor belt, the length of the transition section should not be too small. For the fiber core conveyor belt, the length of the transition section is 1.3 times the distance between the idlers; since the allowable elongation of the steel cord conveyor belt is 0.2%, the length of the transition section is calculated according to the formula L≥2.67cc B, where B is the bandwidth , M; d is the groove angle of the idler, rad. If the L value is much larger than the distance between the supporting rollers, several transition roller groups with a decreasing groove angle sequence should be installed between the drum and the first group of supporting rollers to prevent dripping and sprinkling.
3. Drive roller diameter.
Bending stress will occur when the conveyor belt passes around the roller, causing the core to fatigue. The smaller the diameter is, the greater the bending stress is. Obviously, increasing the diameter of the drum is beneficial to improving the service life of the conveyor belt. However, after increasing to a certain value, the bending stress is not significantly reduced, and the volume of the equipment is increased. Therefore, in order to ensure that the bending stress of the conveyor belt is not excessive, the minimum diameter of the roller should be limited. The principle of choosing the diameter D of the driving drum is: when the multi-layer core conveyor belt uses a mechanical joint, D ≥ 100i, mm (i is the number of canvas layers); when the vulcanized joint is used, the joint is based on the trapezoidal overlap, which is easy to be under the bending stress Peel off, so D≥125i, mm. When the mechanical joint is used for the whole core conveyor belt, D≥K8,mm (k depends on the parameters of the core skeleton material; 8 is the thickness of the core, mm). When using steel cord conveyor belt, D = (150 ~ 200) (t, mm (d is the diameter of the wire rope, mm). The diameter of the reversing drum is based on the conditions such as the diameter of the driving drum, the percentage of the force, and the wrap angle of the belt to the drum. determine.
4. Feeding device.
The structure of the feeding device is reasonable or not, which largely determines the service life of the conveyor belt. In order to reduce the wear and impact stress of the material on the conveyor belt, the technical requirements f-1 of the design and selection of the feeding device are: the speed and direction of the material on the conveyor belt should be approximately the same as the belt speed; minimize the drop of the material, In particular, it is necessary to prevent large pieces of material from falling directly onto the conveyor belt from a high place; the material should form a free continuous stream of material inside the feeding device, and the material can be uniformly loaded into the middle of the conveyor belt in the correct shape. There is a phenomenon of material accumulation and sprinkling; as far as possible, the powder and fine blocks are first discharged onto the conveyor belt to form a cushion, and then the block material is loaded. A buffer roller group should also be installed at the loading point to reduce the impact of the material on the conveyor belt. The installation position of the feeding funnel must ensure that the material falls between the two groups of buffer roller groups, rather than falling into a certain group of buffer On the idler.
5. Convex arc radius.
When the conveyor line is provided with a convex arc section, there is also a large tensile stress on the edge of the conveyor belt when passing through, which causes the conveyor belt and idler to fail prematurely, so the radius of the convex arc section should not be too small. When using steel cord conveyor belts, the radius of the convex arc section should not be less than (75 ~ 85) B.