Common Failures and Solutions of the Center Shaft Frame Assembly in a Raymond Mill

Persistent Powder Leakage at Lower End of Center Shaft Without Abnormal Vibration in Raymond Mill

On-site at a calcium oxide (quicklime) powder production line: The Raymond mill operates smoothly, with no abnormal vibration, no sticking or unusual noise, and stable rotational speed. However, persistent powder leakage occurs at the sealing position of the large gland at the lower end of the center shaft. The leaked calcium oxide dust spreads along the machine frame, covering the coupling and reducer housing, causing poor heat dissipation in the drive mechanism and accelerated aging of seals. Long-term operation can easily lead to a series of failures such as drive overheating and dust ingress into bearings.

Troubleshooting: After sequentially ruling out issues such as bearing seizure, abnormal drive clearance, coupling failure, and bent main shaft, the machine was disassembled to inspect the center shaft frame assembly. The diagnosis confirmed failure at the junction between the center shaft sleeve and the base, with the sealing structure completely damaged.

Fault Analysis: The connection between the center shaft sleeve and the base is a weak point of the equipment. If foreign objects such as iron pieces or crushed stones enter the grinding chamber and become trapped between the plowshare and the base, the equipment will continuously withstand torsional impact during operation. Long-term operation can easily cause weld cracks in the sleeve, loosening at the mating surfaces, and ultimately destroy the center shaft sealing structure. This hidden danger shows no obvious symptoms in the early stage and is easily missed during routine inspections.

Solution: Clean out residual material and accumulated powder from the grinding chamber to improve heat dissipation and avoid secondary wear. Replace the sleeve with an original factory part. Inspect and replace damaged shaft components and bearings. Calibrate shaft accuracy. Tighten bolts according to specifications. Reassemble the sealing components.

Preventive Measures: Install a strong magnetic iron remover and a 30 mm aperture vibrating screen at the feed inlet to block metal and large hard objects at the source. Use rivet fixing for the plowshare assembly to prevent bolt loosening from creating foreign objects. Inspect shaft end sealing condition weekly. Inspect sleeve welds and mating surfaces monthly. Given the moisture-absorbing and caking characteristics of calcium oxide, replace the felt seals and packing every three months.

Sudden Plowshare Bottoming and Overall Roller Assembly Sinking Without Warning in Raymond Mill

On-site at a building materials powder production line: The Raymond mill was operating normally without any warning when a sudden plowshare bottoming and overall sinking of the roller assembly occurred. The grinding clearance of the equipment became completely uncontrollable, the finished product fineness fluctuation exceeded ±15%, and the overall effective production capacity dropped by more than 20%, failing to meet production requirements.

Troubleshooting: After sequentially examining common causes such as bearing wear, coupling misalignment, center shaft deformation, and frame loosening, the machine was disassembled. Inspection revealed that the tapered bore surface of the spider frame had worn by more than 0.3 mm, and the fit clearance with the center shaft had seriously exceeded the allowable limit, completely losing its positioning and support capability.

Fault Analysis: Tapered surface wear of the spider frame is a gradual, hidden fault. In the early stage, there are no obvious abnormalities in vibration, noise, production capacity, or fineness, making it difficult to detect through routine inspections. Once plowshare bottoming and fineness fluctuations occur, the liner plates, plowshares, and grinding rollers will have already sustained irreversible damage, significantly increasing repair costs.

Solution: Replace the entire worn spider frame that has exceeded the tolerance. Repair by welding or build-up welding is strictly prohibited. Use the contact dye check method to verify the tapered surface fit, ensuring a contact area of no less than 85%. Thoroughly inspect the grinding chamber liner plates, plowshares, and grinding rollers. Repair usable components and replace damaged ones. Readjust the grinding clearance according to standards to ensure stable finished product fineness.

Preventive Measures: Designate the tapered surface fit as a key inspection item. Recheck bolt tightening torque weekly. Disassemble and inspect the tapered surface wear amount quarterly. Replace immediately when the wear reaches the warning value of 0.15 mm. Regulate equipment load; avoid long-term operation exceeding 10% above rated capacity.

Sudden Machine Seizure with Simultaneous Drive System Failure in Raymond Mill

On-site at an ore processing production line: The Raymond mill suddenly seized during operation, triggering the safety protection device simultaneously. After shutdown, manual barring was completely locked. Disassembly confirmed that the plowshare in the grinding chamber had completely bottomed out and seized, while the drive system had also shifted and the reducer was damaged by impact. This was classified as a major equipment failure.

Troubleshooting: After ruling out single failures such as sleeve fracture, bearing seizure, and frame loosening, it was determined to be a combined failure caused by severe wear of the spider frame and galling of the center shaft taper, resulting from accumulated long-term hidden hazards leading to sudden shutdown.

Fault Analysis: The spider frame wear was not addressed in a timely manner, causing the tapered surface fit clearance to continuously expand, gradually losing its positioning and support function. Under the weight of the equipment and material impact, the plowshare frame and grinding rollers sank as a whole, causing the plowshare to bottom out and seize. The instantaneous巨大扭力 (enormous torsional force) impacted the drive system, resulting in coupling misalignment and reducer damage, forming a chain reaction of equipment failures.

Solution: Disassemble the center shaft frame assembly. Replace the worn spider frame and the center shaft with taper damage. Correct the coaxiality between the motor and reducer. Inspect the coupling and adjust drive clearance. Thoroughly inspect all grinding chamber components. Replace damaged parts and clean debris from the chamber. After reassembly, perform a no-load test run for 2 hours, monitoring parameters such as vibration and temperature rise. Resume production with material only after normal operation is confirmed.

Preventive Measures: Implement a monthly special maintenance program for the center shaft frame assembly, focusing on inspecting the tapered surface fit clearance and contact condition. If any abnormality in vibration, fineness, or production capacity occurs, shut down immediately for inspection. Strictly control feed particle size; prohibit oversized materials from entering the mill.

Operation and Maintenance Optimization Solution for Raymond Mill Center Shaft Frame Assembly

Based on the analysis of multiple on-site fault cases, most failures of the Raymond mill center shaft frame assembly are not sudden or instantaneous. Instead, they develop gradually through long-term accumulation of issues such as foreign objects entering the chamber, hidden wear of key components, operating equipment while it is in a faulty condition, and prolonged overload operation.

Equipment operation and maintenance do not require blind, high-frequency overhauls. The core focus is on three tasks: controlling foreign materials at the feed inlet, performing periodic inspections of key components, and responding quickly to abnormal conditions. Through routine and standardized maintenance procedures, the failure rate of the center shaft frame assembly can be reduced by more than 80%, effectively avoiding sudden failures and unplanned downtime.

For common issues such as powder leakage, plowshare bottoming, machine seizure, and production capacity fluctuations, we provide professional correction and optimization solutions, with 24-hour rapid response, and offer free fault diagnosis and technical guidance.