The crossbeam of the vibrating screen is a beam that supports the vibrator on the top of the screen frame, also known as cross-girder. Generally, screen equipment with a box-type vibrator has a very strong crossbeam. And it determines the useful life of the vibratory screen equipment. However, the crossbeam often meets the fracture problem, and after fracture is not easy to repair. Affecting production seriously. Vibrating screen troubleshooting, 3 reasons：fracture of vibrating screen crossbeam. As follows:
1. Operational used factors
1) Loose bolts
When Bolt Loosens, the movement of the two vibrators will destroy the circulation of the inertia force of the beam. The exciting force produced by the vibrator impacts the crossbeam violently. The crossbeam fracture because of getting an abnormal impact force.
2) Material deposit
Exciter beams often accumulate material deposit, if not cleaned up in time, it will cause the beam of vibrating screen parts wear severity and break.
3) Overload or load working
Overload or load working has big damage for the spring and motor of the screening, and the constant overload working will change the spring’s elastic coefficient of the screen machine. The screening equipment will have a difference in the amplitude of the front and the back The movement track of the material changes. The impact on the screen frame and the side of the screen increases, cracking occurs.
4) Improper feeding
If the production system improper feeding, the impact of material is not only to the screen machine local wear, the horizontal impact will destroy the overall force balance. Then the impact of incorrect feed on the screen machine life is particularly important.
5) the exciting motor abnormal work
The abnormal operation of the exciting motor can directly lead to the fracture of the beam. There will be abnormal sound before a similar situation occurs. Some daily maintenance method mistakes are very easy to cause this kind of accident, such as the high temperature of the exciting machine with water cooling. It has a great influence on the life of the vibration exciter and screen machine beam.
6) Exciting force too large
The exciting force too large, the load of the screening machine bigger. It affects the use of life of crossbeam of vibratory screen seriously.
2. Design factors
The function of the crossbeam is supporting the vibrator and transmit the exciting force. The forces acting on the main girder include:
Gravity: includes the gravity of the vibrator and the gravity of the main beam itself.
Exciting Force: The exciting force generated by the vibrator is all borne by the crossbeam.
Inertia force: The inertia force produced by the vibrator and the beam during the vibration of the sieve.
In addition to gravity, the exciting force and inertia force is alternating loads. And the exciting force is aslo a concentrated force. Therefore, the design of the beam not only to calculate the strength but also in the structure to consider the stress reasonable, as far as possible to reduce the weight.
On the side, the two ends of the beam and the side plates of the sieve frame are connected by high-strength bolts. So the specification and quantity of bolt must correct calculation.
In order to avoid the risk of girder fracture in design, it is necessary to carefully choose screen manufacturers, choose higher reliability stone crusher manufacturers.
3. The manufacturing factor
Vibratory screening equipment manufacturer must in the light of the vibrating screen design. And attention to the technical requirements of the mark. If there is cursoriness in manufacturing, the beam is easy to go wrong.
There are a few things to note when manufacturing:
1) Welding: must use the stipulation welding Rod, can not have the welding flaw, the welding craft must guarantee the welding distortion to be small.
2) Adopt reasonable technology to ensure the geometric tolerance of the beam.
3) Heat treatment as per drawing.
Measures for crossbeam cracking
The usual way to deal with the cracks is to open the groove in the crack for welding. Then replenish the plate. The crack treatment of the parts is usually riveted or welded by adding plates, and the replacement of parts is carried out when necessary. The riveting effect is generally good because the connection will not produce vibration direction of the internal stress. The welding adaptability is wide, but it is difficult to avoid the welding residual stress when dealing with the cracks.
Measures for control of welding residual stress
① The stress control generally adopts the reasonable welding sequence to make the weld contract and preheat freely as far as possible. The temperature difference of weld bigger, the stress of remnant bigger, the cooling speed faster, the transformation stress bigger. Preheat can decrease the temperature difference and reduce the cooling speed, co-contraction. The shrinkage of the weld is restrained by the cooling metal nearby. And the tensile stress is relieved or partially relieved if appropriate technical measures are taken to allow the cooling metal to contract in whole or in part.
② Heat treatment is commonly used for stress relief, mainly refers to a post-welding annealing treatment. Annealing heating temperature is generally 600 °c-650 °c, holding time is 4min-5min per mm thickness in generally. Then cooling, 100 °c-150 °C can be free cooling in the air.
Low-temperature treatment to eliminate welding stress on both sides of the weld with an oxygen-acetylene torch heating. The certain distance behind the torch with a water pipe spray water cooling.
There is a fixture fixed welding to eliminate deformation stress, hammering to eliminate stress, low-frequency vibration method to eliminate welding stress.
The fracture of the girder is one of the common faults of the vibrating screen. We are not anxious after encountering it, to find out the reason and take corresponding measures so as to resume production as soon as possible.
Types of vibrating screens
Vibrating screening equipment according to weight and purpose can be divided into mining screens, laboratory screening, rotary vibrating screen, linear vibrating screen, circular vibrating screen and so on.