Industry knowledge

1. Diameter of driving roller.

When the conveyor belt bypasses the drum, it will produce bending stress, which will cause the core fatigue. The smaller the diameter is, the greater the bending stress is. Obviously, increasing the diameter of the roller is conducive to improving the service time of the conveyor belt. However, when the diameter is increased to a certain value, the bending stress does not decrease significantly, and the volume of the equipment (SH è B è I) will also increase. Therefore, in order to ensure that the bending stress of the conveyor belt is not too large, the minimum diameter of the roller should be limited. The principle of selecting drive roller diameter D is: when mechanical joint is used for multi-layer core conveyor belt, D ≥ 100I, mm (I is the number of layers of canvas); when vulcanized joint is used, it is easy to peel off under bending stress due to trapezoidal lap joint, so D ≥ 125I, mm. When the mechanical joint is used for the integral core conveyor belt, D ≥ K8, mm (k depends on the parameters of the core frame material; 8 is the core thickness, mm). When steel cord conveyor belt is used, d = (150-200) (T, mm (D is the diameter of wire rope, mm). The diameter of the reversing roller is determined according to the driving roller diameter, the force percentage and the angle of the belt to the roller.

2. The idler (g ǔ n) has a groove angle.

The bearing branch usually adopts the trough idler group composed of three sections of idlers, and the angle between the side roller and the middle roller is called the trough angle. The heat-resistant conveyor belt is composed of multi-layer rubber cotton canvas (polyester cotton cloth) or polyester canvas covered with heat-resistant or heat-resistant rubber and bonded together by high-temperature vulcanization. It is suitable for conveying hot coke, cement, slag and hot castings below 175 ℃. Within a certain limit, the larger the slotting angle is, the greater the material flow (unit: cubic meter per second). However, when the grooving angle exceeds the grooving capacity of the conveyor belt itself, the conveyor belt will not be close to the middle idler during no-load operation, which leads to strong wear and unstable operation of the belt edge; when the conveyor belt is in heavy load operation, a large folding stress will inevitably occur at the corner of the side idler and the middle idler, which will cause the longitudinal fracture of the conveyor belt or the rapid peeling of the canvas layer. Therefore, in the design, it is required that the groove angle of idler must be consistent with the groove forming capacity of the selected conveyor belt, and this principle should also be observed when replacing a new conveyor belt in use. Generally, the groove angle of idler is 30. When the conveyor belt grooving performance is good, it can be increased to 35.

3. Transition section distance.

The conveyor belt section between the head and tail rollers of the conveyor and the first group of carrying rollers (supporting the conveyor belt and material weight) is called the transition section. Rubber conveyor belt with tropical, wear-resistant belt, burning resistant belt, oil resistant belt, alkali resistant belt, alkali resistant belt, tropical, cold resistant belt and other characteristics. It is mainly used for solid material transportation in mining, metallurgy, iron and steel, coal, hydropower, building materials, chemical industry, grain and other enterprises. In the transition section, the conveyor belt changes from groove to parallel or from parallel to groove, and the edge of the conveyor belt is stretched to produce additional tensile stress. The smaller the length of the transition section is, the greater the additional tensile stress is, which causes serious wear on the edge of the conveyor belt and the side idler. As a result, the fatigue phenomenon of the conveyor belt appears prematurely, and even causes the edge of the conveyor belt to break. In order to make the local elongation of conveyor belt edge not exceed the elongation of conveyor belt, the length of transition section should not be too small. For fiber core conveyor belt, the length of transition section is 1.3 times of the distance between idlers; because the allowable elongation of steel core conveyor belt is 0.2%, the length of transition section is calculated according to the formula L ≥ 2.67cc B, where B is the bandwidth, m; D is the groove angle of idlers, rad. If the L value is much larger than the distance between the bearing idlers, several transition idlers with smaller groove angle should be installed between the drum and the first group of bearing idlers to prevent sagging and spilling.

4. Radius of convex arc.

When there is a convex arc section on the conveyor line, there is a large tensile stress on the edge of the conveyor belt when it passes through (t ō ng guॸ), resulting in premature failure of the conveyor belt and idler (supporting the weight of conveyor belt and material), so the radius of convex arc section should not be too small. When steel cord conveyor belt is used, the radius of convex arc should not be less than (75 ～

85)B。

5. Feeding device.

Whether the structure of the feeding device is reasonable or not largely determines the service life of the conveyor belt. In order to reduce the abrasion and impact stress of the material on the conveyor belt, the technical requirements F-1 for the design and selection of the feeding device are as follows: the speed and direction of the material feeding to the conveyor belt should be approximately consistent with the belt speed; the drop of the material should be minimized, especially to prevent the large material from falling directly to the conveyor belt from a very high place; In the feeding device, the materials should form a free and continuous flow, and can be evenly loaded into the middle of the conveyor belt in the correct shape, without material accumulation and sprinkling; as far as possible, the powder and fine block should be unloaded to the conveyor belt to form a cushion, and then the block should be loaded. Buffer idler (supporting conveyor belt and material weight) group should be set at the loading point to reduce the impact of material on conveyor belt. The installation position of feeding funnel must ensure that the material falls between two groups of buffer idler groups, rather than on one group of buffer idler.

6. Conveyor start and brake mode.

In the starting and braking process of belt conveyor, soft starting mode should be used to control the acceleration and deceleration during starting and stopping, so as to reduce the dynamic stress. The heat-resistant conveyor belt is composed of multi-layer rubber cotton canvas (polyester cotton cloth) or polyester canvas covered with heat-resistant or heat-resistant rubber and bonded together by high-temperature vulcanization. It is suitable for conveying hot coke, cement, slag and hot castings below 175 ℃. For the general small and medium-sized belt conveyor, it is reasonable to use torque limiting hydraulic coupling to realize soft start. For the large belt conveyor with long distance and large capacity, due to the large dynamic tension, the controllable soft start device should be used to extend the starting and braking time and reduce the dynamic stress. The commonly used controllable soft start devices are variable speed hydraulic coupling, CST Controllable drive device and variable frequency speed control device