How to Prolong the Life of Crushing Plates

AUTHOR: admin DATE: 22 Jun 2012 06:34:28

The working institution of the jaw crusher is the crushing cavity made up of a motive jaw and a fixed jaw, which is used to bear the giant crushing force and the friction from the materials. To protect the grindable jaw plate, a scaleboard is installed on the appearance of the jaw, which is called the crushing plate. The skin of the crushing plate is always the shape of tooth form, with the angles of the gear peaks of 90 to 120°, which is decided by the nature and the size of the crushing materials. The size of the teeth space is decided by the particles of the materials. While the machine is working, the abrading speed of the two sides of the crushing plate is different, with the downside faster than that of the upside. The life of the crushing plate has a decisive influence on the working efficiency and the cost of the crusher. Thus, to prolong the life of the crushing plate is of great significance. It can be prolonged from the aspects of design, materials selected, package, improvement during the using process and so on.

1. Design and Materials Selected

The tooth peak of the crushing plates of the motive jaw and the fixed jaw should be faced to the tooth valley while being designed. Thus, the crushing plate can squeeze the materials, as well as bend them, which make the materials easy to be crushed. To prolong the life, the crushing plates have been designed as symmetrical shapes for the mediate and small type crushers. When the downside is abraded, the upside can be turned over to be used again. For the large type jaw crushers, the crushing plates are designed as several symmetrical lumps, in order to prevent some of the plates from being abraded. The materials of the crushing plates can be the white cast iron, which has high hardness, good wearability, easy to find and low price, as well as the disadvantages of brittle, easy to be rived and short life. Therefore, to prolong the life of the crushing plate, it is better to use the 12% manganese, usually ZGMn13. The toughness of the Mn is high, in spite of its low hardness (about 210 HB). However, since it has the characteristics of cold working hardening, it is strengthened under pressure constantly. Thus, it can be strengthened ceaselessly with the ceaseless abrading until it is abraded to its limitation. The manganese steel crushing plates should be dealt by the water toughening after being cast. The process of water toughening is similar to the quenching, i.e., to cool the manganese steel crushing plates that have been heat up to 1000 to 1 100 ℃ quickly in the water. After water toughening, the even metallographic structure can be got and fastened, which can avoid the decreasing of the nature because of the phase change during the applying. On the other hand, the price of the manganese steel plate is relatively high.

2. Package

While being installed, the crushing plate should be fixed tightly on the jaw plate. The soft metal (such as Pb, Zn) should be added as the shim and fastened by the bolts between the crushing plate and the jaw plate. When the crusher is working, the crushing plate should not be flexible, or the crushing plate will be easy to broken or abraded. Therefore, the installing of crushing plate is important to prolong its life.

3. Improvement during the Using Process

When the machine is working, since the crushing plate is working directly with the materials, the impacting force is very strong, especially when crushing the materials of high hardness, which can lead to the vibrating of the bolts, the loosening of the nuts, the noise caused by the abrading of the crushing plate, even can lead to the drop and the broken of the crushing plate to stop the production. It is not enough just to fasten the bolts and nuts before setting up the machine. The problems should be solved case by case. For example, the spring against pine vibration reduction device can be used to solve the problem of the loosening of the crushing plates to prolong the life and improve the efficiency.

4. Conclusion

The prolonging the life of crushing plate should be considered from the aspects of design, materials selected, package, improvement during the using process to improve the working efficiency of the jaw crushers and reduce the cost of production.