The chain reaction after filling material failure: technical analysis of the vibration from the gap between the driven cone to the main frame

In the operation system of the cone crusher, the connection state between the crushing wall (moving cone) and the main shaft determines the transmission efficiency of crushing force and the stability of the equipment. When there is a gap between the two and the filling material fails, most on-site managers are concerned about the shortened service life of the lining plate, while the severe vibration of the main frame is often ignored or misjudged as other faults. In fact, this type of vibration is not only possible, but often a clear signal of further damage to the equipment.

1、 The core function of filling material is not simply "filling joints"

The broken wall is fitted onto the main shaft through a conical hole, and the two are not in direct rigid contact, but rely on filling materials (usually epoxy resin or zinc based alloy) to achieve the following functions:

Transmitting crushing force: evenly transmit the reaction force received by the moving cone in the crushing chamber to the main shaft and eccentric part;

Maintain alignment accuracy: Ensure that the rotation axis of the crushing wall coincides with the main axis;

Buffer impact load: absorbs instantaneous impacts generated by working conditions such as iron and superhard materials.

When the filling material fails due to aging, fatigue, casting process defects, or long-term overload, the above functions will be gradually weakened.

2、 Mechanical behavior changes after gap formation

After the filling material fails, there is a relative motion space between the broken wall and the spindle, forming a micro gap. During device operation, this gap can cause two types of abnormal movements:

1. Relative rotation in the circumferential direction

Under the combined action of inertial force and crushing force, the shattered wall may experience circumferential sliding or periodic impact around the main axis. This kind of dynamic cone 'self rotation' becomes unstable, causing the originally evenly distributed crushing force to become an alternating load.

2. Radial swing

When a gap exists on one side of the mating surface, the broken wall will experience radial displacement during the rotation process, resulting in the overall rotation trajectory of the moving cone being out of circle.

The above two movements overlap with each other, causing the actual motion state of the moving cone to deviate significantly from the designed motion trajectory.

3、 Vibration transmission path: from the driven cone to the main frame

The vibration of the crusher mainframe is essentially the result of the unbalanced inertial force generated by the moving cone being transmitted and amplified through the support system.

1. Formation of unbalanced excitation force

Under normal conditions, the moving cone and the spindle form a rotating system with uniform mass distribution and stable motion trajectory. Once the filling material fails, the moving cone undergoes eccentric motion relative to the main shaft, causing the center of mass of the system to deviate from the center of rotation, resulting in a periodically changing unbalanced centrifugal force.

The magnitude of this force increases significantly with the increase of rotational speed, and within the typical speed range of 200-400 revolutions per minute for cone crushers, it is sufficient to cause significant vibration of the entire machine.

2. Rigid amplification of transmission path

Unbalanced forces are sequentially transmitted to:

Gap between eccentric sleeve and copper sleeve

Rack spindle sleeve

Main frame structure

When the vibration frequency is close to the natural frequency of a certain part of the equipment (such as the frame or base), resonance phenomenon will occur, manifested as severe shaking of the main frame, loosening of the anchor bolts, cracking of the lubricating oil pipeline, etc.

3. The mutual intensification of vibration and wear

The existence of gaps causes micro motion wear between the contact surface of the moving cone and the spindle, which further widens the gap and exacerbates the unbalanced force. This positive feedback process can cause the device to develop from mild vibration to severe vibration within hours to days.

4、 On site verifiable correlation phenomena

In actual production, the following phenomena can be used as the basis for judging the vibration of the main frame caused by the failure of the filling material:

No load vibration is less than load vibration: When the equipment is idling, the vibration is within the allowable range. After carrying the material, the vibration increases significantly, indicating that the unbalanced force is related to the crushing force and points to abnormal motion of the moving cone.

Vibration varies with feed particle size: As the proportion of large blocks in the material increases, the vibration intensifies, indicating displacement of the crushing wall under larger impact loads.

Abnormal increase in oil temperature: The swinging of the moving cone causes an increase in local contact pressure of the copper sleeve, and the increase in lubricating oil temperature often occurs before vibration.

Uneven wear on the broken wall surface: The wear surface presents an asymmetric and locally severe wear pattern, which is evidence of the non-circular trajectory of the moving cone.

5、 Suggestions for handling

When it is confirmed that the vibration of the main frame is caused by the failure of the dynamic cone filling material, simply tightening the anchor bolts or adjusting the discharge port cannot solve the problem. Reasonable disposal methods include:

Shutdown inspection: Measure the relative displacement between the moving cone and the spindle, and check if the flange connection bolts are loose;

Re casting of filling material: Thoroughly remove the old filling material, clean the contact surface, and re pour epoxy resin or zinc alloy according to the process requirements to ensure that the curing time and temperature meet the standards;

Coaxiality verification: After the filling material solidifies, measure the rotation trajectory of the moving cone or use a laser centering instrument to verify the concentricity between the main shaft and the crushing wall;

Joint damage investigation: Check whether there are any strains or abnormal wear on the eccentric copper sleeve and the frame copper sleeve, and replace them according to the situation.