Factors that influence the operation of screw conveyors

To put it simply, a conveying device is to transport the material from one side to the other through the conveying tool. In the middle of the 17th century, people used ropeways to transport bulk materials. In 1887, Archimedes invented and produced a screw conveyor. After continuous improvement, the screw conveyor was officially used for industrial transportation. A screw conveyor has advantages such as simple structure, convenient operation and easy maintenance. It has gradually emerged in the development of the national economy and is widely used in metallurgy, mining, construction, power plant, cement plant, etc. In order to adapt to different kinds of occasions, screw conveyors are continuously improved and subdivided into various types.

Advantages of screw conveyors
• Simple structure, reliable operation, 
and low maintenance cost
• Closed feeding groove, which has little contamination to the environment and is easy to transport powdery, odorous materials, or materials with high temperature (up to 2000 °C)
• Conveying materials can be loaded at any point on the line, multi-point unloading is also achievable.
• The conveying method is reversible - A screw conveyor can transport materials to two aspects at the same time, mixing, cooling and stirring can also be done in the material conveying process.
• The geometry of the feeding groove is large and can withstand a certain bending moment.

What factors need to be considered when conveying materials by the screw conveyor?
The advantages of screw conveyors are numerous, but we can't lower our guard when conveying materials. Pay attention to the following points to ensure that there are no mistakes in material transportation.

 1. The water content of the material
 2. The physical property of the material 
 3. The installation site of the conveyor
 4. Blade
 5. Rotate speed
 6. The outer diameter of the screw
 7. Pitch
 8. Feeding methods

The water content of the material - The water content of the material directly affects the transport efficiency. If the material has a large amount of water, during the transportation process, the material tends to adhere to the spiral blade or the inner wall of the conveyor. As the conveying process goes on, the amount of adhered material increases correspondingly, resulting in a corresponding decrease in the amount of transportation. In addition, the material that has been adhered for a long time requires manual cleaning, which will seriously affect the efficiency of transportation.

Temperature, grinding performance and corrosivity of the conveying material - In short-term transportation, the effect of materials with high temperature, grinding performance and corrosivity on the conveying pipe wall is relatively small. But in the case of long-term use, the wear and tear caused by these three factors will lead to frequent repair and replace, which undoubtedly increases the expenses. And if the wear part cannot be replaced or repaired in time, the materials may leak during transportation.

Conveyor installation site - The conveyor should be installed in a stable and well-closed place. Especially for U-shaped shell, the sealing performance of the shell itself is general. If the conveyor is placed outdoors, it is likely to affect the conveying effect. In addition, enterprises should choose an appropriate site from the perspective of the company itself and social morality.

Blade - Materials of different properties have different requirements on the blade shape of the screw conveyor.

Rotate speed - The faster the speed of the screw conveyor, the better the conveying effect. However, the conveying effect of the screw conveyor is related to the design of the equipment itself, and the speed must meet the standard of the critical speed. For many conveyors, if the rotate speed exceeds the critical speed, the material will jump and roll perpendicular to the conveying direction, which reduces conveying efficiency, and leads to larger energy consumption, and more serious wear and tear on the equipment.

The outer diameter of the screw - When the relevant parameters are stable, the axial movement
s the peed and circumferential speed of the material in the feeding groove become larger as the rotate radius of the material increases. When selecting screw conveyor, the blade and the rotating shaft are selected according to the material characteristics. The larger the diameter, the better the effect, but for the open screw conveyor, the outer diameter of the screw increases the manufacturing cost and is not conducive to cooling. Besides, the outer diameter does not necessarily have to be an integral multiple of 500.

Pitch - The dimension of the pitch is related to the speed of material transport. There is a corresponding relationship between the choice of the helical pitch and the outer diameter of the screw. The larger the screw, the larger the corresponding outer diameter of the screw. After determining the outer diameter of the screw, there is a minimum pitch corresponding to it, and this is a relatively suitable pitch.

Feeding methods - There are two typical feeding methods for conveyors: horizontal type and gravity type. The so-called horizontal type feeding means that the material particles can obtain the horizontal speed through a certain method (pneumatic force, horizontal spiral, etc.), and the material is conveyed to the feeding port through the horizontal flow guiding device for waiting for transportation; the gravity type feeding material passes the material particles along the gravity. The feed is carried in the direction of falling, and the material is conveyed to the feed port of the screw conveyor through the flow guiding device for transportation.


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