LM Vertical Mill

LM Vertical Mill

 Fault solution for LM Vertical Mill reducer

Case of LM Vertical Mill reducer

The cement grinding system of a certain company is the combined grinding system of CKP240 LM Vertical Mill + 4.8 x9.5m ball mill. The mill production time is more than 210 t/h, the cement distribution power consumption is about 32KWh/h. The supporting LM Vertical Mill is 2 400 mm in diameter of the grinding plate, three tire grinding rollers, and the disc rotational speed is 33.5 r/min. After three and a half years of operation in May 2014, the inspection found that The planetary gear and reducer flange of the reducer are broken and forced to shut down.

If the whole machine returns to the factory to repair at least two months, and the freight and repair costs are higher, seriously affecting the peak season cement production and sales. On the basis of comprehensive consideration, the field disassembly inspection was carried out. By improving the high-strength bolt type and anti-loosening measures of the connection between the planetary frame and the output flange of the reducer, and at the same time, improving the data size of the pin transmitting torque, and matching the reaming and reaming holes, the fault of the reducer was quickly solved in only 8 days, saving 5. The maintenance cost of about 0 yuan ensures the normal production and operation of the reducer.

Main parameters of motor reducer for LM Vertical Mill

Motor model: YRKK710-6, power: 2240Kw, speed: 994r/min, reducer model: JLP220-WXA, input power: 2300Kw, speed ratio: 29.6. JLP series reducer is bevel gear parallel axis planetary gear reducer structure of three stages. The planetary frame and the output flange are assembled by 16 M42 high strength connecting bolts and 12_50mm cylinder pins.

LM Vertical Mill fault inspection

During the demolition process, partial damage occurred in the following parts:

  • 1. The 4 sets of 16 connecting bolts of the reducer planetary frame and the output flange are all cut off.
  • 2. The 12 transmission pins of the planet carrier and the output flange are respectively broken 3 segments, and the pin holes are deformed ellipses.
  • 3, three grade inner gear ring has two teeth end face falling about 25-30mm, there is a partial crack in one tooth.
  • 4, the planet gear has two tooth ends to drop about 20mm.
  • 5. The outer teeth of the coupling of the secondary gear shaft have 6 teeth end face local drop about 20-30 mm, and 3 teeth have local cracks.
  • 6. The inner support of the center cover of the planet carrier is broken and damaged by copper blocks.

Fault analysis of LM Vertical Mill reducer

After opening the LM Vertical Mill, it is found that there are many friction in the seal labyrinth of the reducer's output disc and sparks are produced. The operator of the central control room is immediately notified to stop the mill. After about five minutes, the labyrinth of the output disc is red. After on-site observation, it is found that the seal of the reducer's output disc is nearly 10 mm offset from the shell, and the flange connection bolt of the output disc is found. Cut off, detach each segment of the pressure plate further, draw out the cylindrical pin, and find that each pin breaks 3 segments respectively.

The LM Vertical Mill used in cement line is JLP220 type reducer. The loading pressure of LM Vertical Mill is strictly controlled within 10 MPa (designed loading rating pressure is 12 MPa). The maximum operating current of main motor is not exceeded 140A (operation is controlled below 90% of rated current 158A for the protection of stable operation of equipment). The temperature of interlocking protection of equipment system is measured. Vibration measurement, pressure measurement, metal detectors and other electrical protection systems have been running safely and effectively. The protection vibration value of the reducer is set at 3.5mm/s when the roller is lifted, and when it reaches 5mm/s, the main motor of the mill is stopped. The vibration value of the normal operation is generally below 2.8mm/s.