| As the critical equipment in the transport field, the belt conveyor is moving towards long distance, large capacity, high speed, big dip. But the sudden increase of the tension follows when starting-up and braking, and the moving of the belt, throwing of materials, breakage of belt sometimes occurs. In order to improve security, the curvature radius is usually increased blindly, causing larger scale, higher manufacture and transport cost. So the urgent problem is to modify the existing straight conveyor to curve conveyor, i.e. how to determine the curvature radius and properly arrange turning structure. All of these need detailed analysis of the turning structure in order to find the geometric relationships between the curvature radius and other parameters.Reliable and practical software for conveyor design and analysis is urgently needed in the conveyor field. Currently, there are large amount of softwares for conveyor design all over the world, such as Helix Delta-T developed by Australia, Pro-Belt5.0 developed by America, Sidewinder developed by AC-Tek and Beltstat developed by CDI.This paper is based on the background that the curvature radius of belt conveyor is oversized. With the reference from domestic and international, this paper summarizes the current development of belt conveyor, detailedly introduces the method of how to turn and main structure. In the paper the structure and function of the practical software Helix Delta-T is discussed and the model using this software is established. This paper takes the conveyor stress and strain intoaccount for both horizontal and vertical belt conveyor, and takes belt and materials as a single unit for mechanical analysis. And the formula for calculation of the curvature radius is gained. Helix Delta-T is used for tension validation of the formula. The main researches are as follows:(1) The purpose and significance are introduced, the development direction, main problem are brought up, and research findings are summarized, while the method, principle and development trends of belt conveyor are simply described.(2) The comparative practical conveyor design software Helix Delta-T is used for conveyor modeling. The paper detailedly introduced design steps and principle for determining the important data of conveyor.(3) In the paper the important part is the mechanical analysis of the turning structure and deducing the curvature radius formula required. According to the force status of turning and force balance, the formula is derived. And the formula is validated by turning restrictions. The current formula ignored the influence of idler's installed obliquity and inner curve's elevation angle on curvature radius, which are the main factors for reducing the radius. And both the factors are fully considered in this paper, so the formula is more accurate.(4) In the research on vertical turning structure, mechanical analysis is performed under concave and convex arc, and curvature formula that meets requirements is derived. With considering the practical situation, the paper makes research on non-horizontal state of the initial turning point (that is, the slope starts to turn). And the paper also considers the centrifugal force, which makes the formula closer to reality.(5) Use Helix Delta-T to perform mechanical validation on the formula. The design of conveyor turning part is based on the tension. According to the radius which is determined by the conclusions in the paper, the turning part of conveyor is designed. Though the design report of Helix Delta-T, it is confirmed that the belt can meet the tension required for safe operation.The structure of turning part is detailedly studied in the paper. It is found that the arrangement of the idler has great influence on the curvature radius. The super elevation angle and installed obliquity in inner curve are main parameters for balancing the tension of belt. And the transverse force induced by the two parameters is the main factor for reducing the curvature radius. However theexisting references usually simplified or ignored the two parameters, which will result in a large deviation. Use the formula that come from the paper can reduce the curvature radius so that the manufacture and transport cost can be reduced. And it can provide theory reference for the design of conveyor turning.
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