Introduction To Jaw Crusher—Four Major Structures

Introduction to Jaw Crusher—Four Major Structures

How does the toggle plate safety device protect the entire machine?

The toggle plate of the jaw crusher looks ordinary, but it is responsible for two tasks. It can transmit the crushing force, and more importantly, it plays an insurance role. When non-crushed objects such as iron blocks fall into the crushing cavity, the toggle plate will be broken or bent first. This design directly absorbs the impact force on the toggle plate to avoid causing the eccentric shaft, movable jaw and other core components to bear excessive loads.

There is a quarry in Ningbo. During the operation, lumps of iron material entered the crusher due to negligence. Generally, the problem can only be solved by inspecting and repairing the entire machine. However, when choosing a jaw crusher with a standard toggle plate, you only need to replace the toggle plate, and the cost is less than 200 yuan. However, if the eccentric shaft is damaged, the repair cost will often exceed 20,000 yuan. This is what the safety device actually means.

The core component of the rotating body is designed like this

The movable jaw assembly is composed of a No. 35 cast steel bracket and a movable jaw plate. After quenching and tempering treatment, the strength has been greatly improved. After the bracket is cast, it must undergo ultrasonic flaw detection to ensure that there are no sandhole cracks inside, so that it will not suddenly break when it withstands repeated impacts.

The bearing is a double-row radial spherical roller bearing, which has its own self-aligning function. Even if there is a slight deviation during installation, it can automatically compensate. With the use of special grease, the bearing life can reach more than 30,000 hours. The eccentric shaft is made of No. 45 steel and has been quenched and tempered. Its surface hardness can reach HRC45. The wear resistance of the journal is significantly better than that of ordinary steel.

The tooth shape of the jaw plate determines the crushing efficiency

The surface of the movable jaw plate adopts an optimized tooth shape design, and the surface of the fixed jaw plate also adopts an optimized tooth shape design. The crushing efficiency of the two is improved by about 15% compared with the ordinary flat plate. Introduction to the jaw crusher – four major structures, the tooth height has been strictly calculated, and the tooth pitch and tooth shape angle have also been strictly calculated. This design can bite large stones without cracking due to the tooth tip being too thin.

The material chosen is high manganese steel ZGMn13. The surface of this steel will harden quickly when subjected to strong impact, and the hardness increases from the initial HB200 to over HB450. A stone factory in Jiangxi reported that after using this jaw plate, the replacement cycle of a single set was extended from 2 months to 4 months, and the output was stabilized at 150 tons per hour.

The discharge opening can be adjusted flexibly and accurately

The adjustment of the discharge opening of the jaw crusher has a direct impact on the discharge particle size. Currently, two mechanisms are commonly used in the jaw crusher to repair the wear and tear of the eccentric shaft bearing position by riveting and welding . The wedge-type adjustment relies on moving wedges to change the discharge gap, which can achieve stepless adjustment. The ejector-gasket type relies on increasing or decreasing the thickness of the gasket to control the opening size.

In actual operation, the wedge-type adjustment is more convenient. The operator only needs to turn the screw and can achieve the adjustment without stopping the machine. Its adjustment range is between 5mm and 30mm. However, the gasket-type adjustment requires stopping the machine to replace the gasket. However, its accuracy is higher and it is suitable for sand and gravel production lines that have strict requirements on particle size.

Why welding frames gradually replace casting

The traditional frame is cast from medium-carbon steel. Even though its overall performance is relatively good, defects such as pores and shrinkage are prone to occur during the casting process. Nowadays, more manufacturers will choose frames welded by medium-carbon steel plates, and in this way, multiple ribs can be added to strengthen the ribs to compensate for the stress problems caused during the welding process.

Compared with casting, the welding frame manufacturing cycle is shortened by 40%, and the cost is reduced by about 20%. After a Yunnan machinery factory adopted welded frames, the frame cracking complaint rate dropped from 3% to 0.5% during the warranty period. The key process is preheating before welding and tempering after welding, which can effectively eliminate residual stress.

Guard plate replacement must not be ignored

The left and right side walls of the cavity of the jaw crusher will be impacted by stones and then subjected to direct friction, and the wear process is very fast. The guard plate used on the side wall is specially made of high-chromium cast iron . The jaw crusher's eccentric shaft bearing position is worn and riveted to repair . The hardness of this material can reach HRC60 and upwards, which can be said to be relatively high. However, even under such conditions, when hard granite is crushed, the service life of the guard plate is only in the range of 4 to 6 months.

The guard plate is fixed to the frame with bolts, and its removal and replacement only takes half an hour. It is recommended that the operator check the wear condition of the guard plate every other week. When the wear of the guard plate thickness exceeds 50% of the original thickness, it should be replaced immediately. Otherwise, once the side walls of the rack are worn, the maintenance cost will inevitably increase significantly.

Different operators in the sand and gravel industry, have you encountered any unexpected malfunctions of the jaw crusher during normal production? You are welcome to share your experience in the comment area, like this article and forward it, so that more colleagues can avoid detours.