1. Problems and Analyse
The vibratory separator is mainly suitable for the classification of spherical tin-solder powder (3a grade solder powder). The screen is generally divided into two layers, the upper layer is a 325 mesh screen, and the lower layer is a 500 mesh screen. The powder between 325 and 500 mesh is the desired product. At the initial stage of putting into operation, the effect of the sieve machine has been unsatisfactory. The main problems are that the screen is easily torn, the screen has a high rate of plugging, and it is difficult to clear and the screening efficiency is low.
Analyze the above problems, the reasons for the characteristics and use of the vibratory separator structure. The main reasons are:
a. The mesh is not tight enough or the tension is uneven
b. The vibration motor is not turning correct.
c. Material accumulation.
d. Contains a large number of particles close to the separation point.
e. The material is spherical particles, static electricity or agglomeration will occur, and the mesh is clogged.
f. The weight phase angle adjustment is not in place.
2. Improvement measures
2.1 Change the bonding process of the screen mesh
1. Lay the screen on the grid.
2. Use the hoop to fix the screen to the grid, and adjust the tension of the screen mesh by adjusting the hoop bolt.
3. Apply glue along the perimeter of the grid and firmly attach the screen to the grid.
4. Remove excess screen along the perimeter of the grid.
2.2 Change the way of cleaning screen mesh
The vibratory separator mainly relies on the ball that is continuously beating to prevent the material from blocking the screen hole to clean the screen mesh. However, the screen blocking hole is particularly serious during use, which indicates that the effect of this scheme is not obvious, and it is difficult to control the height and strength of the bounce, which is easy to cause damage to the screen. After the research, ultrasonic vibration is used instead of the elastic ball cleaning screen, which combines the ultrasonic generator, the ultrasonic transducer and the vibratory separator to the purpose of efficient screening and clearing.
2.3 Adjusting the weight angle
Adjusting the phase angle of the weight can change the movement track and residence time of the material on the screen: when the phase angle is less than 15°, the powder stays on the screen is the shortest time, the screening efficiency is not high, and only it is suitable for general screening; When the angle is 45°, the powder stays on the vibratory separator sieve surface, has the longest time and is suitable for fine screening. When the phase angle is greater than 45°, the powder running track is close to the center for special screening.
In order to adapt the screen machine to the requirements of spherical tin-solder powder, the powder not only requires screening accuracy of more than 90%, oxygen content can not exceed 0.1 ‰, but also ensures screening efficiency, so the time of the powder on the screen surface should not be too long or not be too short. It has been proved by experiments that the phase angle of the general weight is between 15 and 45 degrees, depending on the number of layers of the vibratory separator.
3. Use effect and economic benefit
Through the improvement of the screen tensioning method, the cleaning method and the reasonable adjustment of the weight phase angle, the current situation of frequent vibratory separator mesh damage is completely changed, the screen blocking rate is greatly reduced, and the service life of the screen is effectively improved. Taking the 3a grade spherical tin-solder powder as an example, the average service life of each screen (with 325 mesh) can be increased by 10 to 20 times, the screening efficiency of the powder is increased by 20%, and the economic benefit is significantly improved.