Section I Components and protection of belt conveyor
Structure of belt conveyor
The belt conveyor is composed of: 1. Belt 2. Transmission drum 3. Reversing drum (tension heavy hammer drum) 4. Motor 5. Reducer 6. Upper idler 7. Lower idler 8. Adjusting idler 9. Buffer idler 10. Spring cleaner 11. Tail cleaner 12. Backstop 13. Guide chute 14. Tension device 15. Support (including head, tail and middle) and other components.
Working principle of belt conveyor
The belt is wound through the driving drum and the tail redirection drum to form a endless annular belt. The upper and lower sections of the belt are supported on the upper and lower supporting wheels, and the tension device gives the belt the tension required for normal operation. During operation, the main drive drum drives the belt to run through the friction between it and the belt, and coal and other materials move on the belt together with the belt conveyor.
Structure introduction of each equipment
- Conveyor belt: in the belt conveyor, the conveyor belt is not only a bearing component, but also a traction component, which is used to carry materials and transmit traction. Conveyor belt is the most important and expensive part of belt conveyor. The price of conveyor belt accounts for about 30% – 40% of the total investment of conveyor.
- Classification of conveyor belt: it is generally divided into fabric core tape and steel rope core tape.
- Composition: upper rubber coverage, polyester canvas core, lower rubber coverage and side rubber.
(1) The polyester canvas core is lined with nylon thread, and the warp and weft threads are intertwined with each other. The longitudinal tension is borne by the warp, while the weft mainly bears the transverse tension. Through this way of weaving, the warp and weft are bent, resulting in great elasticity of the tape. The multi-layer fabrics are bonded with rubber to form a fabric core.
(2) Function of covering glue: it is used to protect the middle fabric core from mechanical damage and the influence of surrounding media. It is relatively thick. It is the bearing surface of the conveyor belt and is in direct contact with materials and is impacted and worn by materials.
(3) Function of the lower covering glue: it is the contact side between the conveyor belt and the supporting supporting rod, which mainly bears the pressure. In order to reduce the collapse rolling resistance of the conveyor belt when running along the supporting roller, the lower covering glue is generally thin.
(4) Function of side covering glue: when the conveyor belt deviates and the side is in contact with the frame, protect it from mechanical damage. Therefore, it is often composed of wear-resistant rubber.
Section II Supporting rod
Function of supporting rod:
The supporting roller is used to support the conveyor belt and the weight of materials on the conveyor belt, reduce the running resistance of the conveyor belt, and make its sag not exceed a certain limit, so as to ensure the smooth operation of the conveyor belt along the predetermined direction.
Basic requirements of supporting rod:
The quality of the idler affects the service life of the belt and the running resistance of the belt. The maintenance or replacement cost of supporting roller is an important part of the operating cost of belt conveyor. Therefore, its basic requirements are “durable, small rotation resistance, smooth surface of supporting wheel, small radial runout, reliable dust prevention of sealing device, good lubrication of bearing, light self weight and compact size”.
Classification of idler:
According to its arrangement, it can be divided into: bearing supporting rod group and return supporting rod group. According to its purpose, it can be divided into groove supporting rod, parallel supporting roller, buffer supporting roller and self-aligning supporting roller.
- Grooved bracket: It is mainly used as the supporting roller on the loaded part of the belt conveyor, which is generally composed of three short supporting rollers (the groove angle of the belt conveyor is mostly 35 °, and the transition is 10 ° and 20 °). With groove angle, the belt can run smoothly. Due to the increase of conveying capacity, under the condition of the same output, it is possible to reduce the belt width by one level and save a lot of belt. The diameter D of the supporting mixer is related to the width B, the material stacking weight R and the belt speed V. Generally, in the dropping pipe, in order to make the materials centralized, and avoid the material from spreading.
- Buffer mixing: It is used as the supporting roller under the material guide groove of the load
- ed part of the belt conveyor. At the material receiving place, due to the material falling onto the conveyor belt, it is inevitable to impact the belt and supporting roller. The use of buffer supporting roller can protect the belt and avoid the impact damage of supporting roller bearing.
- Self aligning idler: It is used to adjust the longitudinal center line of the conveyor belt to prevent and reduce the wear and torsion caused by the deflection of the belt during operation, as well as the scattering of conveying materials.
Types of self-aligning support mixing: It is divided into one-way rotating automatic centering supporting rod, forward inclined grooved centering supporting rod, reversible automatic centering supporting rod and conical automatic centering supporting wheel. Under no-load branch, the supporting wheel is a parallel self-aligning supporting wheel and a V-shaped forward inclined return supporting rod.
- Return idler: It is mainly used as the lower supporting rod of the no-load branch of the belt conveyor to support the belt in the no-load section. Some can be used to remove the sticky coal on the surface of the no-load section, and some can be used to reduce the sticky coal.
- Spiral roller: It is mainly to remove the accumulated coal on the belt surface of the unloaded support section. During the movement, the tape drives the spiral support rod to rotate. There is a deflection angle between the movement direction of the thread and the movement direction of the tape, so that there is a friction force in the left and right directions. The magnitude of this pair of friction forces is equal and the direction is opposite. During the movement, remove the accumulated coal on the tape.
- Transition idler: The transition supporting roller group is arranged between the end drum and the first group of bearing supporting roller to reduce the edge stress of the conveyor belt and avoid tearing the belt and scattering.