Due to the increase of coal output and lump coal weight in recent years, there are higher requirements for the safe operation and economic performance of belt conveyor. The traditional coal drop point uses the buffer supporting wheel to protect the belt operation at the coal drop. Due to the poor buffer capacity of the buffer supporting rod, the lump coal impact is easy to fall off, the small contact area between the buffer supporting roller and the conveying belt, and the belt between the buffer supporting plate is easy to sag, the belt in the coal drop point section is wavy, which can not meet the current requirements of safe production.
1 System to its original state
Due to the heavy transportation task of raw coal, long operation time and large blanking blocks, the buffer support mix is often smashed, stuck or fallen off, and the buffer support frame is deformed. Due to the smell number and big space of coal conveyor belt in installation,which causes the conveyor belt to appear wavy.As a result, the impact of lump coal falling on the conveyor belt will reduce the service life of the belt, and the workload of daily maintenance is increasing, and the capital investment is large, which seriously affects the safety production of coal mine.
In the process of coal mine safety in production, in order to further ensure the reliability of the underground transportation system and safety of mine production, the main transportation belt transportation links, after more than of coal bunker, production process, production process must have a reasonable structure, convenient and reliable, strong operability, low cost, impact resistant and strong practicability belt coal device. The designed buffer bed can effectively reduce the impact of block coal accumulation and block coal falling process on the belt, avoid the belt tearing caused by the buffer support.
2 Overview of impact bed
Impact bed is used to replace the buffer bracket for the material point of the belt conveyor, slow down the impact and damage of the material on the belt, avoid sharp and large materials on the tearing and smashing of the belt, prevent the overflow of material Li Siluo. Buffering machine is mainly composed of round quack buffer plate, spring, spring seat and yellow sleeve. The arc buffer plate is made of 812 steel plate, and the arc buffer plate is supported by 820 steel plate to ensure the overall stability of the arc buffer plate. The spring sleeve protects the spring well, preventing the use of the spring from being exposed, prolonging the service life of the spring, and it is convenient to replace when the spring is damaged. By the arc buffer plate and spring to replace the original buffer tray, the buffer plate is designed into a circular arc to support the belt, the use of support area increases, through the spring expansion to slow down the impact of the lump coal on the belt, to prevent the belt in the process of operation by sharp material tearing and smashing the possibility.
2.1 Characteristics of impact bed
a) The efficiency of buffer bed. It means that it can effectively absorb the impact force when it is affected by the impact force, and through its own physical characteristics, on the one hand, it can protect the conveyor belt and prevent the conveyor belt from tearing; on the other hand, it can use its own characteristics to prolong its overall service life;
b) Durability of buffer bed. The so-called durability is in the design of the buffer, fully considering the actual impact size and working conditions, the force of the buffer is fully simulated and analyzed, so that in the design of the buffer into consideration of various factors, to ensure that the buffer in the use of the process of durable.
2.2 Advantages of buffer press
a) The design of circular arc buffer plate ensures the uniform surface contact force of the conveyor belt, which effectively prevents the crushing force of the supporting wheel caused by the lump coal falling, and greatly reduces the probability of longitudinal tearing caused by the belt being penetrated by iron or sharp objects; b) The spring expansion fully slows down the impact load when the lump coal falls, greatly reduces the impact of the lump coal on the conveyor belt, and protects the conveyor belt and the frame from being damaged; c) Effectively eliminate the material splashing and scattering caused by the unevenly stressed conveyor belt; D) The buffer press is simple to install, durable and convenient to maintain.
3 Key points of buffer press bed
Design to meet the high efficiency and durability of the buffer, the following factors must be taken into account
a) the size of impact force. The impact force caused by different media, particle size and blanking height is very different. It is necessary to carefully verify the relevant parameters and simulate the impact force with professional accounting formula and software. The load-bearing capacity used in the design should be greater than the simulated load-bearing capacity;
b) Maximum impact force principle. When calculating the impact force of the buffer bed, it is necessary to simulate the maximum and worst working conditions, taking into account all factors to ensure that the design bearing capacity of the buffer bed is greater than the actual bearing capacity;
c) Choose high quality springs. The impact force brought by the decomposition of the material medium is mainly through the performance index of the spring, especially the deformation of the single coil spring working limit load, the stiffness of the single coil spring, the working limit load. Only select high quality high elastic spring can ensure the effective decomposition of impact force, play a very good protection of the conveyor belt buffer. Buffering bed is the best product instead of buffer support, showing outstanding wear resistance and impact resistance, high reliable performance, provide comprehensive support for the conveyor belt, ensure the blanking area between the buffering bed and conveyor belt surface to surface contact, make loading material in the process of falling force buffering. The selection of spring is: material 60Si2MnA, diameter 12 mm, spring diameter 70 mm, working limit load 6 031 N, single ring spring working limit load deformation 10.18 mm, single ring spring stiffness 592 N/mm.
4. Disadvantages of buffer support
a) The buffering support mixing buffering capacity is poor.And it can not well absorb the strong impact force of lump coal falling, easy to break the buffer support, causing longitudinal belt tearing hidden danger; b) The buffer support is easy to fall off when it is frequently impacted by lump coal, and the support seat mixed with the buffer support is easy to scratch or tear the belt; c) Buffer support rod and conveyor belt for line contact, suspended between the two support mixing, vulnerable to block coal and other sharp hard objects through the two relief punching belt, and stuck between the hub and the coal point, resulting in longitudinal belt tearing; d) The belt between the two brackets is easy to sag, which makes the belt in the area of coal falling point wavy, resulting in lump coal scattering and environmental pollution; e) The surface elasticity of the buffer support is poor, and the rubber surface is easy to be damaged when running for a long time. f) The rotating bearing cup of the buffer bracket is subjected to impact when it is long, and the assembly clearance of the bearing cup is too large, and the seal is easy to fail, resulting in the damage of the bracket bearing, and the bracket does not rotate, which is easy to tear the tape; g) underground environment is very bad, there is water, raw coal moisture, coal slime, coal dust, humid air, resulting in serious corrosion of the support.
5 Performance comparison of conveyor buffer support
A) Anti-tear effect. Buffer rod group spacing is large, sharp material falling easily inserted into the belt, stuck in the support between, causing tearing belt; Part of the cushion rubber mixture hardness is too large, the quality is poor, under the condition of repeated impact, the cushion mixture will be broken in a short time, become a direct hidden trouble of the conveyor belt tearing. Buffering machine design presents triple buffering, and belt running presents the force direction, can effectively prevent belt tearing;
B) Overflow prevention effect. Cushioning wheel sets are arranged in heavy loads, and the installation mode is wavy, resulting in poor sealing effect during belt operation. The force and running direction of the buffer make the belt run in parallel, and its friction coefficient is very low, reduce belt friction and prevent belt deviation;
C) Overall buffering effect. The buffering and rolling groups are all single form buffering, and the buffering effect is poor. The buffering machine provides the overall support of the belt in the blanking area, presenting triple buffering, effectively reducing the impact on the buffering machine, and protecting the conveyor belt well.
Belt conveyor has become one of the main transportation equipment in coal mine production.The correct use and maintenance of belt, and the improvement of the belt conveyor in the process of conveying the utilization rate of belt, which is particularly important to make it be economically reasonable,safely operate. After selecting the falling coal point buffer, not only improve the equipment opening probability, reduce the labor intensity of workers, and improve the safety factor, enhance the level of standardized management, reduce belt wear, late investment cost is less, in the process of safe production in the coal mine played a great role.