How to solve the disk mill failure
February 28, 2023
The disc mill is the most critical equipment for high yield pulping, generally consisting of a moving disc and a fixed disc in the grinding area, commonly known as double disc mill, which can be used as a hot mill or a medium or high consistency pulper, with the advantages of high capacity, low energy consumption and low fiber damage.
Here we explain how to deal with failures of disk mill during operation.
In production operation, a combination of manual inspection and online monitoring is used to diagnose the fault of pan mill. Manual inspection is mainly to monitor and check the bearings and high voltage junction box and other parts by experience combined with vibration measuring instrument and temperature measuring instrument, and to analyze and judge the fault situation comprehensively; online monitoring is to analyze and judge the various data collected by the system chain control.
Common failures are as follows:
- Vibration of pan mill
- Entry of hard objects
- Disc into and out of the knife dilemma
- Decrease in grinding capacity
- Bad quality of grinding pulp
1.Vibration of pan mill
- The deviation of coaxiality between the mill and the motor is too large, causing vibration.
After running for a period of time, the gear coupling needs to be loosened and reset with a percentage table calibration.
- After the new grinding pad is turned on
There may be two reasons for vibration.
One is that the grinding plate moving disk is not balanced.
This requires a new replacement of the grinding plate.
The second is that the parallelism of the fixed disc and the moving disc deviates greatly, and vibration occurs after loading.
Should first adjust the grinding plate fastening screws, check the parallelism of the two discs to within the range.
- Vibration caused by excessive mounting clearance of bearings or damaged bearings.
This can be determined by brass listening and vibration measuring instrument inspection.
- The cantilever shaft of the moving disk produces deflection deformation causing vibration.
The spindle should be replaced in time.
- The grinding teeth are broken by hard objects causing vibration.
This affects both the quality and yield of the grinding pulp and the operation of the mill.
It is necessary to replace the grinding plate in time.
2.Entry of hard objects
Hard objects enter the grinder and noise of different sizes and natures occurs.
If it is a small metal object, an ear-piercing sound will occur, and the grinding plate gap should be adjusted as soon as possible to separate the discs.
If it is a larger hard object, the grinding should be stopped immediately and the grinding chamber should be opened for inspection and treatment.
3.Disc into and out of the knife dilemma
If the phenomenon of unstable knife feeding and releasing occurs, first of all, the hydraulic cylinder should be abandoned, then check the hydraulic station oil level and check whether the cylinder piston rod is stuck.
4. Decrease in grinding capacity
If the grinding capacity decreases by about 30%, the grinding plate must be replaced, which is also the principle of grinding plate replacement.
It is mainly because: the grinding teeth in the crushing area of the grinding plate are broken or the grinding plate teeth groove is blocked; the grinding plate is used for a long time and worn seriously; the spiral feeder blade is deformed seriously and feeding is difficult, etc. will cause the grinding capacity to drop.
5. Bad quality of grinding pulp
The reasons are as follows: the gap between grinding pieces is too large; the grinding concentration is too small; the grinding pieces are badly worn; the cooking temperature is low and the material pieces are not softened enough; the pulp is not washed well and the viscosity is large, etc.