Sinking roller is a key component in galvanizing or tin plating units, which is prone to various failures due to long-term exposure to high temperature and corrosive environments. The following summarizes common problems and improvement measures.

Common Faults

1. Mechanical seal failure

-Performance: Seal leakage, heat loss failure (such as dry friction on the end face, resin precipitation from graphite static rings, aging of rubber bellows).   

-Reason:

-Excessive or insufficient pressure on the end face leads to high temperature rise (accumulation of frictional heat).   

-The rubber of the sinking roller shaft neck expands and changes hardness due to high temperature, affecting the sealing fit.   

-Insufficient installation accuracy, such as deformation of the groove or improper axial clearance.   

2. Adhesion of zinc and zinc slag on the roller surface

-Performance: Zinc slag adheres to the roller surface, resulting in quality defects such as scratches and roller marks on the surface of the strip steel.   

-Reason:

-The temperature of the zinc solution is high (460-470 ℃), and zinc slag (such as Fe ₂ Al ₅) is prone to deposit on the rough surface of the roller.   

-The corrosion resistance of the roller surface material is insufficient or the roughness is unreasonable (too high can easily scratch the strip steel, and too low can affect transmission).   

3. Roller surface wear and groove damage

-Performance: Changes in roller surface roughness, damage to groove shape, reduced transmission efficiency, and causing strip deviation.   

-Reason:

-High temperature zinc liquid erosion and mechanical friction cause surface wear.   

-Excessive bearing clearance or low installation accuracy can cause radial runout.   

4. Short overall service life

-Performance: The sinking roller is frequently replaced offline (the original design life is often less than 15 days).   

-Reason: Poor material wear resistance, insufficient thermal stability, and improper process control.   

solution

1. Optimize the design of mechanical seals

-Improve installation accuracy: Strictly control the static clearance of the static ring and the compression amount of the rubber bellows to ensure the parallelism of the end face.   

-Improved cooling structure: Adopting an external circulating cooling system to reduce the temperature of the sealing end face (avoiding exceeding 120 ℃).   

-Adjust the end face pressure ratio: Control the frictional temperature rise by optimizing the load coefficient K or the elastic force of the corrugated tube.   

2. Improve the material and structure of the roller surface

-Upgraded material: The roller body is made of 316L stainless steel (with strong corrosion resistance), and the shaft sleeve is made of high cobalt alloy (to improve wear resistance).   

-Optimize groove design: Replace the parallel flow zinc groove with a spiral flow zinc groove, and use centrifugal force to shake the zinc slag off the roller surface.   

-Control roughness: The roller surface roughness should be kept below Ra1.6 to avoid scratches caused by excessive roughness or transmission affected by insufficient roughness.   

3. Strengthen process and installation control

-Strict installation accuracy: Align circular runout and coaxiality in a unified assembly frame to reduce bearing clearance.   

-Process parameter optimization:

-Reduce the galvanizing temperature, shorten the immersion time, and minimize the generation of zinc slag.   

-Control the aluminum content of zinc liquid (0.16% -0.19%) to avoid excessive iron dissolution.   

-Regular maintenance: Seal the coating to block micro pores and enhance corrosion resistance.   

4. Comprehensive preventive measures

-Regularly inspect the aging of rubber components and replace any abnormal parts in a timely manner.   

-By monitoring the roller surface status online, the wear trend can be detected in advance and the process can be adjusted.   

summary

The sinking roller faults are mainly caused by high temperature corrosion, mechanical wear, and installation process issues. By upgrading materials, optimizing structures, strengthening cooling, and implementing refined management, its lifespan can be significantly extended (such as increasing from<15 days to>30 days in the case), and product defects can be reduced.