Probability Sieve also called Probability screen.Probability sieve is a new screening mechanism used on the railway ballast cleaning machine designed based on the principle that the ballast slides relatively along the screen surface and the polygon effect of the link transmission. Probability sieve can make the small ballast with small particle size get more sieving, while the big particle size has little sieving, which greatly improves the sieving rate and can extend the cleaning cycle by about one time.
Vibration probability sieve adopts multi-layer (generally 3 to 6 layers), large inclination angle (generally 30° to 60°), large screen hole (screen hole size is 2 to 10 times the separation particle size).The basic structure of the probability screen and the ordinary vibrating screen is the same, and it is also composed of three parts: the screen box, the vibrator and the supporting (hanging) device. However, the structure has four characteristics: large number of layers, large inclination angle, large screen hole and short screen surface. The screen box of the probability screen is composed of a screen frame and 3 to 5 screen surfaces. The screen frame is a polygonal box body welded or riveted with steel plates and section steel. The screen surface is installed on the screen frame. Several inclined screen surfaces can be placed on each screen frame. Currently, most probability screens are equipped with three or five layer screen surfaces. The slope of the screen surface of each layer increases from top to bottom. Considering that the material has a larger running speed on the screen surface, a large screen angle is adopted. The inclination angle of the uppermost sieve surface is 15°～35°, and the inclination angle of the uppermost layer shall prevail. The sieve surface of the lower layers will increase by 4°～6°. The sieve holes are the largest, and the size of other sieve holes decreases from top to bottom layer by layer . In general, the uppermost sieve is 10 to 15 times larger than the separation particle size; the lowermost sieve surface should also be at least 1.5 to 2 times the separation particle size; the middle layer of sieve holes can be in the Choose between the top and bottom sieve holes as appropriate. Because only under the condition of adopting a large inclination screen surface, it is possible to use a large mesh screen surface that is much larger than the separation particle size, so the inclination of the screen surface and the size of the screen hole should be considered uniformly.
Working principle of probability screen:
In terms of working principle, it is also significantly different from ordinary vibrating screens. Probabilistic screens actively use the probabilistic principle to complete the entire screening process at a fast speed, so that the time required for material screening is only for the vibrating screen. 1/3～1/20, and its handling capacity per sieve surface area is 5-10 times greater than ordinary vibrating screen. Therefore, it can be considered that the sieving performed in the probability sieve belongs to "rapid sieving".
Probability screen structure drawing:
The sieve surfaces of the probability sieve are all linearly vibrated, so like the ordinary vibrating sieve, a biaxial inertial vibrator can be used, which is driven by two motors. For a probability screen with small volume and light weight, a pair of vibration motors can be directly mounted on the screen box to excite the vibration, and the two excitation motors operate synchronously to generate linear vibration. Due to the different connection methods between the screen box and the shaker, there are two types of shaker with different vibration systems: one is that the shaker is directly fixed to the screen bar, like an ordinary linear vibrating screen, this probability The screen is a linear vibration system. The other is that the exciter is installed on the balance frame. The balance frame and the screen box are elastically connected. The screen box is hung by a spring. This probability screen is a double-mass vibration system. Probability sieves basically use suspension devices with springs, and small sieve machines with light weights are adjusted directly by hanging devices in cylindrical coil springs. According to the requirements of the plant conditions and configuration, the probability screen can also be installed in a seat type. Like a linear vibrating screen, the screen box is supported on the machine base through a set of springs.
Technical parameters of probability screen:
|model||Sieve||Material size（mm）||motor||Vibration time（1/min）||Double amplitude（mm）||Production capacity（t/h）||Screening efficiency|
|Sieve layer||Screen surface structure||Grading size（mm）||Screen area（m²）||Screen surface inclination（°）||Models and specifications||power（kw）|