The bucket lifter is the main equipment of the cement mill system. The hoisting machine shell is damaged by the material and is a big problem that plagues the safe production and operation of the enterprise. Most of this type of wear occurs in the feed hoist in the early roller press combined grinding system. The wear parts are mainly on the lower surface and both sides of the hoist, which is likely to cause serious material run on the production site, dust flying, and worsening production. surroundings.
Since the hoist is generally on the side of the building and the height is above 40m, the repair of the casing is difficult, and the risk of high-altitude operation is high. At the same time, the wear of the casing will reduce the overall strength of the hoist, and there is a hidden danger of safety. Although the post-design has corrected this problem, it is still common for bucket elevators that were designed early and are still heavily used.
1 Bucket lifter structure and working principle
The bucket lifter is composed of a housing lifting device, a head wheel device, a transmission device, a tail wheel device and a tensioning device.
The bucket is mounted on the double chain, and the chain is wound around the head gear shaft plate, and the head wheel device is rotated by a transmission device composed of a motor, a hydraulic coupler and a speed reducer (the speed reducer has a slow disk mechanism - a backstop). Therefore, the vertical lifting movement between the chain and the bucket is made. The material enters the bucket from the feed inlet of the bucket tail, the bucket is turned over, the material is discharged, and the lifting operation of the material is completed cyclically.
The normal loading capacity of the material of the hoist hopper is 70%~75%. When the material is raised to the radius of the head wheel, the material will be turned over with the bucket. When the height of the head wheel is high, the material will be discharged downwards, and the material is discharged through the discharge port. cycle.
When the material is filled with buckets, the material will rise to the radius of the head wheel and gradually overflow with the bucket. The spilled material will rush to both sides of the shell and the chain. When the head wheel is high, the material will pour out downwards and enter the lower opening. . However, due to the large amount of material, there is no net cleaning between the head wheel and the lower feeding port. The remaining material continues to be poured into the casing until it is turned down, and falls into the bottom of the hoist to complete a cycle.
It can be seen that the impact of the material not only causes wear on the casing, but also causes wear on the hoist chain, reduces its service life, and also causes damage to the transmission system such as the reducer.
2 Cause analysis
According to the survey, the above problems are common in the cement roller press combined with the grinding system. The main reason is that the rolling press is unstable, which causes the phenomenon of material charging. When the material is fluctuating, the hopper of the hoist is overloaded. In severe cases, the hoist can be crushed to death, causing damage to the reducer and the chain of the hoist is broken. The reason why the rolling press occurs is mainly due to the large amount of roller press, the small amount of mill digestion, the increase of material circulation, and the increase of fine powder. After a certain period of time, when the steady flow of fine powder reaches a certain proportion, it is easy to occur. The material is washed, causing the hoist to overload or trip. Therefore, overload is the main cause of scouring, overload or tripping of the hoisting machine, damage to the reducer, and breakage of the hoist chain.
(1) Extend the unloading time of the bucket, reduce the height of the lowering port, extend the lower opening of the hoisting machine downward by 500~800mm, transform the cutting slippery, and externally strengthen the support, generally the net of the bucket can be poured out.
(2) Install the guide groove at a large angle between the discharge port and the bucket head wheel. The distance between the chain and the chain should be 10~15mm. The material should be raised to the radius of the head wheel. The material will be flipped with the bucket. Gradually overflowing, most of the spilled material will slide into the discharge port with the guide grooves on both sides.
(3) Install the lowering tongue at the lower feeding port, and use the waste tape to penetrate the casing, preferably 20mm from the front end of the bucket.
(4) For the problem of frequent hoisting of the hoisting machine, it is necessary to first adjust the operating parameters so that the material throughput of the roller press is reasonably matched with the feeding amount of the mill, and the circulation of the roller press is stabilized to reduce the occurrence of the ramming. The hoist forms a stable stream.
(5) The problem that the hoist often suffers from crushing, inability to start, damage to the backstop, gearing of the reducer, and high current operation of the motor is basically caused by the small design capability. Due to the influence of the site, it will not be replaced as a whole. The motor can be increased by 20% and the reducer can be increased by 1. The above measures can basically ensure the normal operation of the hoist.