Is the loosening or idling of the broken wall (moving cone) related to the degree of wear of the rolling mill wall, apart from the burning of the copper sleeve?

During the operation of a cone crusher, the loosening and idling of the moving cone (crushing wall) are typical malignant faults. In addition to the burning of the eccentric copper sleeve, the wear degree of the rolling bowl wall (fixed cone lining plate) is an important cause. The two are directly related through the force on the crushing chamber, the constraint of the moving cone motion, and the transmission of the overall load. The following professional analysis is conducted from the principles, mechanisms, and impact paths.

1、 Working principle and fault definition of core components

1. Core component functions

Crushing wall (dynamic cone lining plate): Installed on the dynamic cone, it rotates and swings with the eccentric shaft sleeve, and is the active working surface for crushing operations. It achieves material extrusion and crushing through relative motion with the rolling bowl wall.

Rolling bowl wall (fixed cone lining plate): fixed to the frame, serving as a passive working surface, and together with the crushing wall, forming a closed crushing chamber, determining the crushing chamber type, material stress state, and discharge law.

Eccentric copper sleeve: The core support and transmission component of the dynamic cone spindle, which achieves friction reduction and transmission through a lubricating oil film. Copper sleeve burnout is often caused by lubrication failure, local overload leading to dry friction, and high-temperature melting.

2. Fault definition

Loose dynamic cone: The fastening structure between the broken wall and the dynamic cone fails, resulting in radial/axial movement, accompanied by abnormal vibration and noise.

Dynamic cone spinning (runaway): The rotational speed of the dynamic cone far exceeds the design value (no load ≤ 15r/min, heavy load ≤ 5r/min), losing normal swing constraints and exhibiting high-speed rotation, often accompanied by severe vibration, sudden rise in oil temperature, and risk of copper sleeve burning.

2、 The mechanism of the effect of rolling mill wall wear on the loosening/idling of the moving cone

The wear of the rolling mill wall does not directly cause the failure of the dynamic cone, but indirectly induces loosening and idling by changing the geometric parameters of the crushing chamber, the distribution of material forces, and the constraints of the dynamic cone movement. The core mechanism is as follows:

1. Distortion of the fracture cavity shape and imbalance of force on the moving cone

Uniform wear of the rolling bowl wall can lead to an overall increase in the gap between the parallel and conical regions of the crushing chamber; Uneven wear (such as unilateral or localized wear) can cause distortion of the cavity shape and misalignment of the working surface contour.

After cavity distortion, the material is unevenly distributed in the crushing cavity, and the dynamic cone is loaded and biased on one side. Long term biased loading can loosen the fastening structure between the crushing wall and the dynamic cone (such as the cone head and zinc alloy casting layer), causing loosening.

Partial load causes local abnormalities in the clearance between the main shaft of the dynamic cone and the eccentric copper sleeve, leading to a decrease in oil film stability and a sudden change in friction torque, which can easily trigger the dynamic cone to lose control of its rotation and form idling.

2. Sudden change in material crushing resistance and failure of dynamic cone motion constraint

Under normal operating conditions, the frictional force between the material and the crushing wall, as well as the rolling bowl wall, will constrain the rotation of the cone, maintaining a reasonable rotational speed; The wear of the rolling bowl wall will change this constraint condition.

After the wear of the rolling mill wall working surface, the roughness decreases, the curved surface contour becomes smooth, the friction between the material and the working surface decreases, the resistance to the rotation of the dynamic cone decreases, and the speed easily exceeds the design range, causing idling.

Severe wear and tear result in excessive clearance between the crushing chambers, preventing the formation of an effective material layer. During the rotation of the moving cone, there is an "empty hit", and the impact force is transmitted irregularly, exacerbating the loosening and instability of the moving cone.

3. Abnormal load transmission can trigger copper sleeve burning and chain failure

The wear of the rolling mill wall will change the load transmission path of the whole machine, amplify the working load of the eccentric copper sleeve, and form a chain reaction of "wear overload copper sleeve failure dynamic cone idling".

The distortion of the cavity causes the trajectory of the dynamic cone to deviate, reducing the contact area between the main shaft and the eccentric copper sleeve, increasing local pressure, and making the oil film prone to rupture, leading to dry friction and ultimately causing the copper sleeve to burn out.

After the copper sleeve is burned, the moving cone loses effective support and restraint, and its rotational speed sharply increases, directly triggering a "flying car"; At the same time, the metal debris generated by the failure of the copper sleeve will intensify the abrasive wear of the rolling bowl wall and the broken wall, forming a vicious cycle.

4. Deterioration of force on the fastening and support system exacerbates looseness

The wear of the rolling mill wall leads to uneven distribution of crushing force, which will be transmitted to the fastening and support structure of the moving cone

The connection between the broken wall and the moving cone (such as the zinc alloy layer and bolts) is prone to fatigue and cracking due to long-term alternating loads, resulting in the loosening and detachment of the broken wall.

The spherical support of the moving cone (bowl shaped tile) is exacerbated by the tilting of the moving cone, which increases the wear rate and reduces the support accuracy, further reducing the stability of the moving cone movement and accelerating the occurrence of idling.

3、 The correlation boundary between the wear of the rolling mill wall and the burning of the copper sleeve

There is a clear boundary between causality and association between the two, and it is necessary to distinguish between direct causes and indirect effects:

The direct causes of copper sleeve burning include lubrication failure (lack of oil, oil pollution, high oil temperature), improper assembly clearance, poor contact between the spindle/copper sleeve, and over iron/overload impact, which are the direct triggering factors for the idle running of the dynamic cone.

The role of rolling mill wall wear: as an indirect cause, by changing the crushing conditions, amplifying load fluctuations, reducing the reliability of copper sleeve work, and accelerating the burning of copper sleeve; At the same time, burning the copper sleeve will further deteriorate the motion state of the dynamic cone and exacerbate the wear of the rolling mill wall.

Independent fault scenario: Severe wear of the rolling bowl wall can lead to loosening and idling of the moving cone alone (such as complete misalignment of the cavity or complete failure of material constraints), without the need for copper sleeve burning in advance; Copper sleeve burnout can also occur independently due to lubrication and assembly issues, and is not related to the wear of the rolling mill wall.

4、 Key points of fault diagnosis and prevention and control

1. Diagnostic points

Observe the gap between the crushing chamber and the wear status of the rolling bowl wall, with a focus on checking unilateral wear, local grooves, and contour distortion.

Monitor the rotational speed, vibration amplitude, oil temperature, and oil pressure of the moving cone. When the rotational speed exceeds the standard, there is a sudden change in vibration, or when the oil temperature rises sharply, it is necessary to simultaneously investigate the wear of the rolling mill bowl wall and the status of the copper sleeve.

Check the fastening condition of the broken wall, and determine whether it is caused by unbalanced load based on the degree of wear of the rolling bowl wall when it becomes loose.

2. Prevention and control measures

Regularly check the wear of the rolling mill bowl wall, replace it in a timely manner when the uniform wear exceeds the design threshold and the uneven wear exceeds the allowable deviation, and restore the standard cavity shape.

Optimize the feeding system to ensure uniformity, fullness, and no segregation, and avoid exacerbating unilateral wear of the rolling mill bowl wall and dynamic cone bias load.

Strictly control the lubrication system to ensure that the oil quality, pressure, and temperature meet the standards. Regularly clean the oil circuit and replace the filter element to prevent the copper sleeve from burning out due to lubrication failure.

Standardize the installation process of broken walls and rolling mill walls, ensure that the fastening force meets the standard, the mating surface fits well, and reduce the risk of loosening.