1 Introduction
Belt conveyor is widely used in ports, power plants, mines and other places. In the belt mechanism, the support and mixing frame is widely used, which is its important structure. The distance of the belt transportation line is long, the number of belt transportation is large, the application of supporting collection is very large, and there are many times to replace the damaged supporting roller. Depending on the location, the difficulty of replacement varies. It is relatively simple to replace the supporting roller in the ordinary section. Because there are no obstacles above, the drawing height of the supporting energy fruit is generally L M. lift the belt a certain distance from the external supporting roller of Yasuda yihongshile, and the general time is 5 minutes; However, in the guide section m, a 100 mm support for mixing frame is added in the design. Due to the advantages of carrying material skin and small spacing between mixing frames, the replacement is very elegant, and the general time is about 60 minutes. In order to facilitate maintenance and save time, the idler frame is optimized to make it easy to replace.
2. Technical transformation scheme
The height of 100 mm support is added to the guide chute idler frame, and the structure is divided into three parts: idler frame support, middle support and inclined support.When replacing the groove supports on both sides after the transformation, it only needs to remove the four bolts fixing the inclined support, remove the inclined support, install a new idler, and then re fix the four bolts. When replacing the middle groove support, the middle support can slide to the outside after removing the inclined support, slide to the middle after replacing the idler, and finally fix four bolts of the inclined support to complete the replacement of the middle groove support.
After the transformation, the cumbersome process of removing the whole idler frame is omitted, and the process of installing new idler is completed in a large enough space on the outside. The replacement time of groove support is shortened from about 60 min to about 10 min, and the required maintenance personnel are reduced from 3 ~ 5 to 2 ~ 3, which greatly improves the maintenance efficiency.
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3 Calculation and verification
3.1 load analysis
The vertical direction of the idler frame is affected by the gravity of the load and the downward impact force of the coal material. The gravity of the load includes the gravity of coal material, the gravity of buffer supporting wheel and the gravity of rubber belt. According to the actual operating parameters of the belt conveyor: the maximum transport capacity is 4400 T / h, the belt speed is 4.4 M / s, the spacing between buffer idlers is 350 mm, the buffer idlers weigh 38.41 kg, the 250 m belt weighs 14 T, and the calculated weight of the load is 2346 N. The coal material impacts the belt from the throwing roller through the chute. Assuming that the speed of the coal material reaching the lower belt remains unchanged, the downward impact force of the coal material is 1056 N according to the momentum conservation calculation. Considering the special conditions such as material blockage, ensure the safe and effective operation and increase the safety factor by 1.5. Therefore, the maximum vertical downward force on the idler frame is 5103 N.
The idler frame is subject to friction during the operation of the belt conveyor. In special cases, when the idler frame is stuck and does not rotate, the friction is the largest. This is the sliding friction under dry friction conditions. Select the parallel texture of rubber and rubber, and determine the friction coefficient as u = 0.48: the horizontal friction force on the idler frame is calculated to be 2450 N.
3.2 Finite element analysis
3.2.1 support analysis and verification
The stress analysis and operation analysis results of the maximum vertical downward force on the bearing show that the maximum principal stress is less than 235 MPa, which meets the service requirements.
The analysis results of the influence of horizontal friction on the bearing show that the maximum principal stress is less than 235 MPa, which meets the service requirements.
3.2.2 check of middle support and inclined support
The middle support and inclined support are integrated for stress analysis. There are 6 load-bearing points of the material on the supporting roller frame, and the maximum vertical downward force is evenly distributed according to these 6 points. It can be seen that the maximum principal stress is less than 235 MPa, which meets the use requirements.
The influence of horizontal friction on the middle support and inclined support is analyzed. It can be seen that the maximum principal stress is less than 235 MPa, which meets the service requirements.
3.3 Strength check of bolt connection
Analyze whether the bolt connection strength between the inclined support and the support meets the requirements. The guide chute is in the horizontal section, and the vertical downward force has no force on the bolt, so its influence is not considered. The friction force in the horizontal direction has an effect on it, and has a force on the connecting bolt of the support and the support of the supporting frame. The connecting bolt is M16 × 50 four sets of ordinary bolts, where the force is greater than the force at the bolt connection between the inclined support and the support, while the bolt connection between the inclined support and the support is 8 sets of M16 × The strength of 50 stainless steel bolts is higher than that of ordinary bolts. Stainless steel bolts are used to prevent rust and facilitate disassembly, so the bolt connection strength meets the requirements.
Through the above analysis results, the optimized design of the supporting frame structure meets the strength requirements.
4 Conclusion
The optimized split idler frame eliminates the influence of the guide groove in the process of replacing the idler, which makes the installation of the guide groove idler frame convenient, the replacement of the idler simple, saves manpower and time, and achieves good results. After one year of application in a port, this scheme greatly improves the replacement efficiency of the guide chute, saves the labor cost and improves the maintenance efficiency.Read more: Conveyor belt maintenance kits