Jaw crushers are widely used in mining, smelting, roads, railways and other industries because of their simple structure, convenient operation and large crushing ratio. The author has been engaged in installation and commissioning work in Xingaonai Mining for many years and has come into contact with various jaw crushers. Here is a detailed introduction to the common knowledge of jaw crushers.
1. Specifications and classification
The specifications of jaw crushers are expressed by the width and length of the feed port. For example: a jaw crusher with a feed port width of 600 mm and a length of 900 mm is represented as a 600×900 jaw crusher.
Jaw crushers are generally classified according to the width of the feed port. A large jaw crusher has a feed port width greater than 600 mm; a medium jaw crusher has a feed port width of 300-600 mm; and a small jaw crusher has a feed port width less than 300 mm.
2. Working principle and types
When the material is added to the crushing chamber of the jaw crusher (the space composed of the fixed jaw plate and the movable jaw plate), the movable jaw plate swings back and forth periodically. When the movable jaw plate approaches the fixed jaw plate, the material is crushed by squeezing, splitting and breaking. When the movable jaw plate leaves the fixed jaw plate, the material that is crushed to a size smaller than the discharge port is discharged from the lower discharge port according to gravity. The material that is not completely crushed falls to the lower part of the crushing chamber and is squeezed, split and broken again to continue to be crushed.
Although there are many types of jaw crushers, only two types are used in my country's mineral processing plants: simple swing jaw crusher (PEJ) and complex swing jaw crusher (PEF). The pinyin P stands for crusher, E stands for jaw, F stands for complex swing, and J stands for simple swing.
3. Precautions for replacing easily worn parts of jaw crusher
1. Replacement of liner
The fixed jaw liner (tooth plate), movable jaw liner (tooth plate), and side liner (guard plate) of the jaw crusher are easy to wear. Severe wear will lead to larger product particle size. When the liner is initially worn, the liner can be turned around for use, or the upper and lower pieces can be turned around for use. The wear of the jaw plate is mostly concentrated in the middle and lower parts. When the tooth plate is worn off by 3/5, a new liner needs to be replaced. When the liner plates on both sides are worn off by 2/5, they also need to be replaced with new ones.
2. Replacement of mandrel, eccentric shaft, and bearing
If the shaft is not worn much and you just want to repair the geometry, you can turn it on a lathe. However, when the journal size is reduced by 5% after several turns, it is not allowed to turn again and a new one should be replaced.
Since the jaw crusher works under impact load, the babbitt liner on the bearing needs to be recast every two years.
If the eccentric shaft and the bearing, the mandrel and the bearing are worn, and the top clearance is greater than 1.5 times the original assembly clearance, it is necessary to add pads for adjustment or replacement; if the oil groove is worn by 1.5 mm, the oil groove should be reopened and adjusted. When the gap between the connecting rod head cover and the eccentric shaft is worn to more than 1.5 times the assembly gap, it is also necessary to add pads for adjustment or replace with new ones.
3. Replacement of thrust plate
When the thrust plate is severely worn or the front thrust plate is broken, the ore in the crushing chamber must be cleared first, the severely worn or broken thrust plate must be removed, and the movable jaw and the elbow plate on the connecting rod must be checked for damage. Then pull the movable jaw to the vicinity of the fixed jaw, lubricate the working surface of the elbow plate with dry oil, replace the new thrust plate, make it slowly contact with the working surface of the elbow plate, and tighten the horizontal pull rod so that the movable jaw clamps the thrust plate. Tighten the safety cover, connect the lubrication system, and then adjust the size of the discharge port.
The common sense about jaw crushers is mainly the above. In the end, it should be emphasized that for jaw crushers, it is necessary to be more diligent in daily maintenance, which is much less expensive than replacing parts when the machine is broken.