Here, metal wire is selected to weave the screen surface. The screen hole size is 8mm, the diameter of light steel wire d is 2mm, the opening rate is 64%, and the length width ratio is 3:1.
Calculation of handling capacity of circular vibrating screen:
Approximate calculation by formula [7]: (4-1)
Where: – processing capacity calculated by feeding (t/h);
M — Correction coefficient of screening efficiency, see Table 4-10 [7]; M can also be calculated according to the following formula:
M＝
——Screening efficiency;
——Volume treatment capacity per unit area (/· h), see Table 4-11 [7];
——Calculated width of screen surface (m);
＝0.95B；
B — actual screen width (m);
L – working length of screen surface (m);
——The loose density of the material (t/).
According to Table 4-10 [7] and Table 4-11 [7], when the screening efficiency is 98%, M is 0.27, 1.1, 13.30/· h, Q=0.5T/h. According to the actual requirements, the length of the screen surface is taken as three times of the width, that is, L=2B,=0.95B, then:
So B=
The width of screen surface is 330mm, the length is 660mm, and the inclination angle of screen surface is 20 °.
Selection and calculation of motor
P= (4-2)
Where, P – calculated power of motor (KW);
——Vibration mass (kg);
——Amplitude (m);
N – vibration frequency (r/min);
D – bearing times (m);
C — damping coefficient, generally C=0.2;
F – bearing friction coefficient, f=0.005 for rolling bearing;
——Transmission efficiency, take=0.95.
According to practical experience, amplitude is generally selected according to the following range:
Circular vibrating screen=2.5~4mm
Here we take any value=3mm, n=600r/min, P=5kw, d=50mm;
Try to find=
It is calculated that the vibration mass is too large, which will inevitably increase the manufacturing cost. Therefore, it is not used. Now, P is taken as 0.5kw, and it is calculated as 1500.9kg, which is more suitable. Check the Mechanical Design Course Design Manual (Table 12-1) [1]
The motor Y801-4 is selected, the power P is 0.55kw, the speed is 1390r/min, and the mass m=17kg.
The general calculation formula of equivalent dynamic load P () is
P=X (4-3)
Where, X and Y are the radial dynamic load coefficient and axial dynamic load coefficient respectively. See Table 13-5 in Reference [2] for their values. As shown in the table: X=1, Y=0;
P=1.2, so: P=1.2=17.65kw
Calculation of rolling bearing life:
Basic rated life of bearing (4-4)
N represents the rotational speed of the bearing (unit: r/min), which is an index. For ball bearings,=3, and for roller bearings,=. According to the mechanical course design manual, C=69.2KN.
=2639.8h
The calculated life meets the design requirements, so the bearing inner diameter d is taken as 50mm. After checking the mechanical course design manual, it can be concluded that D=90mm, B=20mm.
1.2 Life calculation of bearing
The life formula of the bearing is:
=() (6-4)
Where: unit of is 10r
——Is an index. =3 for ball bearings; =10/3 for roller bearings.
