Calibration and Verification of Key Coordination Gap of Cone Crusher in Planned Maintenance

In the planned maintenance of the cone crusher, replacing the worn lining plate is only a part of restoring its performance. To ensure that the equipment is restored to an efficient and stable working state, and to achieve the expected product granularity, a series of critical mechanical clearances must be systematically calibrated and verified. These gaps directly determine the trajectory of the moving cone, the geometric shape of the crushing chamber, and the dynamic stability of the equipment.

1、 The influence mechanism of core gap on crushing performance

The working principle of a cone crusher relies on precise geometric motion relationships. Under the drive of the eccentric sleeve, the moving cone rotates and swings around the centerline of the equipment. Any deviation in critical fit clearance will disrupt the kinematics of the design, resulting in:

Deterioration of product granularity: The unstable trajectory of the moving cone causes fluctuations in the effective length of the parallel zone and the minimum discharge port size during actual operation, resulting in an increase in the proportion of oversized particles and fine powder in the product.

Decreased crushing efficiency: Energy cannot be fully utilized for laminated crushing, and some is consumed in ineffective friction, impact, and vibration.

Abnormal wear and damage risk: Non design loads acting on lining plates, bearings, and host structures can accelerate component damage and even cause major mechanical failures.

2、 List of Key Coordination Clearances that Must be Calibrated

The following are the clearances that should be checked and calibrated during planned maintenance, except for the assembly of lining plates (specific allowable values must strictly refer to the equipment manufacturer's technical manual).

1. Radial clearance between the main shaft and the shaft sleeve (straight bushing/eccentric bushing)

Function and Influence: This gap determines the radial swing space of the spindle inside the eccentric sleeve and is the most direct factor affecting the accuracy of the dynamic cone swing. Excessive clearance can lead to irregular oscillation trajectory of the dynamic cone, increased impact load, coarsening and instability of product particle size; If the gap is too small, it may lead to poor lubrication, heating, and even shaft hugging.

Inspection and calibration methods:

Measurement: After disassembly, use an inner/outer micrometer to measure the inner diameter of the eccentric sleeve liner and the outer diameter of the main shaft fit, and calculate the difference. Alternatively, after assembly, use a professional gap gauge (such as lead wire indentation method) to measure.

Standard: Must comply with the range given by the manufacturer (for example, the new machine clearance is usually 0.8 ‰ -1.2 ‰ of the shaft diameter, and the maximum allowable wear clearance is generally 2-2.5 times the new machine clearance). If the maximum allowable value is exceeded, the bushing must be replaced or the spindle must be repaired.

2. Gap/contact between bowl shaped tile (spherical bearing) and the spherical surface of the moving cone body

Function and Influence: The bowl shaped tile supports the entire moving cone component. Its contact state affects the vertical positioning and rotational stability of the moving cone. Poor contact (such as local contact and uneven gaps) can lead to unstable support, uneven wear of bowl shaped tiles, and abnormal swinging of the moving cone, seriously affecting the transmission of crushing force and product particle size.

Inspection and calibration methods:

Contact imprint inspection: Apply red lead or blue oil evenly on the bowl shaped tile working surface, install the moving cone and slowly rotate it several times, then lift the moving cone to observe the contact imprint. The ideal contact should be a uniform, continuous, centrally located annular contact zone with an area of not less than 70%.

Gap adjustment: By increasing or decreasing the thickness of the adjusting gasket under the bowl shaped tile support, the horizontal and vertical positions of the bowl shaped tile can be fine tuned to optimize contact. This is usually a delicate adjustment task that requires experience and patience.

3. Gap between eccentric sleeve and frame liner

Function and Impact: This gap ensures that the eccentric sleeve can rotate smoothly within the frame. Excessive wear can cause the eccentric sleeve to shake during operation, transmitting irregular vibrations to the entire cone system and disrupting the stability of the crushing chamber.

Inspection method: It is usually determined by checking the wear of the outer wall of the eccentric sleeve and the frame liner, combined with the abnormal noise and vibration history during equipment operation. When there is severe wear, the lining needs to be replaced.

4. Axial clearance of horizontal shaft (transmission shaft)

Function and Influence: This clearance is controlled by the thrust bearing assembly and adjusting shims, and is used to limit the meshing position of the bevel gears of different sizes. Incorrect axial clearance can alter the gear meshing backlash and contact area, leading to gear noise, abnormal wear, and even tooth breakage, affecting power transmission efficiency.

Calibration method: Use a dial gauge to measure the axial runout of the horizontal axis, and adjust the runout to the manufacturer's specified range (usually 0.1-0.3mm) by adding or removing adjusting shims at the thrust bearing.

5. Clearance between the spherical bearing seat and the frame mating surface (locked state)

Function and Influence: After tightening the locking nut, the spherical bearing seat should be tightly fitted to the frame without any measurable gap. The presence of gaps can cause micro movement of the entire upper support component under the action of crushing force, leading to bolt fatigue, wear on the mating surface, and damage to the main frame.

Inspection method: After final locking, use a feeler gauge to try inserting around the bearing seat flange and the mating surface of the frame. Any measurable gap is unacceptable, and the cleanliness, flatness, or gasket condition of the contact surface must be checked.

3、 Systematic calibration process and recommendations

To ensure the quality of maintenance, it is recommended to follow the following process:

Inspection and recording during disassembly: During the disassembly process, record the visual wear status of each mating pair to preliminarily determine whether replacement is necessary.

Cleaning and measurement: Thoroughly clean all mating surfaces. Measure and record the key dimensions mentioned above (such as spindle diameter, inner diameter of each bushing, etc.) using calibrated measuring tools.

Based on standard decision-making: Compare the measurement data with the assembly tolerances and wear limits in the equipment technical manual. Any component that exceeds the wear limit should be considered for repair or replacement.

Sequential assembly and step-by-step calibration: Assemble in the order from inside to outside and from bottom to top. For example, first calibrate the axial clearance of the horizontal axis, then install the eccentric sleeve component and check its fit with the frame liner, then install the spindle cone component and verify the spindle clearance, and finally install the bowl shaped tile and adjust the contact area.

Final verification and trial operation: After all clearances are calibrated, manually turn the disc to check for smooth rotation and interference. Conduct no-load trial operation, monitor vibration, noise, and bearing temperature rise. When conditions permit, load testing can be carried out and samples can be taken to check the particle size of the product.

Conclusion

The planned maintenance of cone crushers goes far beyond the technical depth of "replacing old with new". The systematic calibration of critical mechanical clearances is a key bridge connecting the replacement of new lining plates and the restoration of equipment design performance. It ensures that the new lining can work in the precise geometric and dynamic environment set by the design, thereby truly achieving the expected crushing efficiency, product granularity, and operational reliability. Neglecting the calibration of these gaps may result in equipment performance not meeting expectations after maintenance, and even lead to new failures due to improper assembly, greatly reducing the value of planned maintenance. Therefore, listing gap calibration as an equally important standard maintenance procedure as major component replacement is a necessary investment to ensure the long-term healthy operation of equipment.