The five core assemblies of a vibrating screen each have a clear function. The screen box carries material and performs screening. The exciter generates vibration. The support assembly carries weight and constrains the motion path. The drive transmits power. The isolation assembly keeps dynamic load away from the foundation. For selection, clarify these five functions first, then check the parameter limits of each assembly. This is more effective than stacking specifications item by item.
Screen box
The screen box consists of side plates, cross beams and screen media. It is the main structure that carries material and performs screening. Side plates usually use Q345B steel, which has higher strength than ordinary carbon steel and withstands long-term alternating load. Side plates connect to cross beams and the exciter base with high-strength bolts or ring groove rivets. Ring groove rivets have high shear strength and do not loosen easily under vibration. They also avoid side plate cracking caused by the heat-affected zone from welding. Large screens and exciter base connections often use this method. Screen media can be metal woven mesh, perforated plate or polyurethane, depending on the material, with openings from 0.1 to 100 mm.
Screen box side plates, cross beams and flanges carry high-frequency alternating stress for long periods. Hansheng Automation can machine screen box side plate connection flanges, cross beam end connections and exciter mounting seats from customer drawings, with material and surface treatment agreed on the drawing. Single units or small batches are supported.
Exciter
The exciter converts motor energy into periodic exciting force. Vibration motors mount directly on both sides of the screen box and have a compact structure. Amplitude is adjusted by the angle between the eccentric blocks at both ends. A smaller angle increases the resultant eccentric force and the amplitude. During adjustment, the eccentric blocks at both ends of the same motor and on both motors of the same screen must be set to the same angle. Otherwise the exciting forces on the two sides are unequal and polarization appears. Eccentric block exciters are belt driven and suit high-throughput applications, with exciting force up to 200 kN and above. The exciting force of a vibration motor is proportional to the square of speed. Speed depends on motor poles and frequency, and variable-frequency control can change vibration frequency without changing eccentric blocks.
Support assembly
The support assembly consists of spring groups and supports. It carries the full weight of the screen box and constrains the box to move only in the design direction. Steel helical springs have high load capacity and stable stiffness, and their temperature range is wider than that of rubber springs. They are the main choice for mining and heavy-duty screens. Rubber springs have high internal friction damping and smaller amplitude through the resonance zone, so operation is smoother. Their temperature range is generally minus 30°C to 80°C, and they age easily under high temperature or oily material. During installation, the height difference between the four spring support points should be kept within 5 mm. Uneven height causes screen surface tilt and uneven amplitude.
Drive assembly
The drive assembly includes the motor, pulleys and V-belts. V-belt drives cushion starting impact and tolerate some installation deviation between the motor and the screen box, so they are widely used on vibrating screens. Mechanical efficiency of an ordinary V-belt drive is usually 0.92 to 0.97, and using 0.95 for efficiency calculation is common practice. Explosion-proof vibration motors cover 0.75 to 55 kW and about 900 to 1500 r/min. Belt tension must be checked regularly. Insufficient tension causes slip and lower efficiency.
Isolation assembly
The isolation assembly mounts between the support base and the foundation. Its function is to reduce the dynamic load transmitted to the building structure. The natural frequency of rubber isolators or composite springs must be separated from the excitation frequency. In design, the natural frequency of the screen box and spring system is usually set at 1/3 to 1/5 of the excitation frequency to avoid the resonance zone during operation. A natural frequency of 5 to 7 Hz is a common design range for rubber isolators. When the frequency ratio falls in a reasonable range, dynamic load transmissibility can be reduced to a low level. Isolation efficiency is not determined by isolator hardness alone. Frequency ratio, damping and installation symmetry together affect the final load transmitted to the foundation.
For selection, material properties such as particle size, moisture and corrosiveness determine screen media and spring type. Throughput from 5 to 800 t/h determines screen box size and exciter specifications. Installation space constrains drive form and support method. Exciter adjustment, eccentric block tightening and spring replacement must be carried out with power disconnected.
Our precision parts machining capability is not limited to excitation and support components for vibrating screens. In addition to tobacco packaging machine parts and filling machine parts, we machine non-standard parts to drawings for printing machines, food machines and other equipment, and we accept small-batch orders for yacht precision parts and RC car precision parts. Hansheng Automation works within precision parts machining. Material, tolerance and surface treatment are agreed on the drawing, and parts are machined and delivered accordingly.
