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In the design or manufacturing industry, conveyors are always encountered, especially belt-type conveyor systems. However, in the design within our industry, the designs of the vast majority of companies or engineers result in belt conveyor misalignment. We must approach the manufacturing process of conveyor belts with care, analyzing the reasons to avoid unnecessary design mistakes. Common conveyor belts for assembly lines include belt types, roller types, and plate-chain types. Here, I will share my personal views on the issues that are of common concern regarding small belt conveyors, and engage in discussions with everyone. I hope I can be corrected if there are any mistakes. Belt conveyors can be as short as just a few dozen centimeters or as long as hundreds of meters; they vary in size. Although simple, they still have their basic structure and principles. Its applications are also very wide, and it is generally used in light industries such as electronics. There are mainly two types of commonly used belt conveyors: PVC belt conveyors and synchronous toothed belt conveyors. Transportation principle: It relies on a motor to drive the drum, and it is the friction between the belt and the drum that propels the conveyor belt, thereby transporting the products. Why does deviation occur, and how can it be prevented and resolved? Theoretically, belt conveyors should provide a smooth flow of material without any sideways movement, but in practical situations we often observe the belt moving from side to side, a phenomenon commonly known as \"deviation.\" Why does it deviate? Since the belt is driven by one or several sets of enveloping rollers at the front and back, it can be simply considered as being rotated by four points in the same plane surrounding the belt. If these four points formed a perfect rectangle, without any deviation at all, then the belt would not deviate from its path. However, due to the accumulation of manufacturing and processing errors in the components that make up the conveyor belt, the belt tends to deviate from its path on a regular basis. In essence, it can be said that there is no conveyor belt that does not deviate at all. There are several main factors that affect this perfect rectangle. 01. Impact of belt quality. The most common types available on the market are PVC, PVK, PU, rubber bands, etc. Each material has different properties, with varying elongation rates; the sources from which these materials are obtained also differ. During the belt processing stage, carelessness on the part of workers during welding can easily result in uneven lengths on the sides of the belt. As a result, the belt does not have a perfect rectangular shape. To ensure that the quality of our belts meets the required standards, we must choose high-quality suppliers who provide superior belts. 02. Impact of the processing quality of the roller. The cylindricity of the cylinder produced by roller processing is insufficient; the rotating shaft is welded to the cylinder body, resulting in poor concentricity, as well as poor fit with the bearings and inadequate contact when installed in the frame. They all tend to cause the drum to move in a swinging motion when it rotates. These factors affect the smooth operation of belt conveyors; we often see uneven belt movement, with fluctuations in height, and many cases are caused by such factors. Poor bearing fitment causes abnormal noises, etc. 03. Like other equipment, belt conveyors also require a good reference point; the frame serves as the lowest level of this reference point. Therefore, for the welding structure, it is necessary to ensure that the welds are accurate and strong, while minimizing manufacturing errors. Inevitably, the design must take into account the possibility of making adjustments. Try not to create rigid structures. 04. Belt slippage. Sometimes, it can be observed that the belt slips while the drum continues to rotate; the belt itself does not move. This phenomenon occurs due to insufficient friction between the belt and the drum. Generally, this issue can be resolved by increasing the size of the drive drum, enlarging the contact surface, increasing the wrap angle, adding patterns to the drum surface, or applying rubber coating to it. 05. Drive of belt conveyors. Generally, a pulling method is used to keep the tensioned edge tight as much as possible during operation; if a pushing method is used, it can easily cause the tensioned edge to move around. This is because the tensioning mechanism in conventional belt conveyors is a semi-loose type of tensioning, without complete fixation. 06. Influence of guide rails and idler rollers. A perfect rectangle cannot be balanced. 07. In cases of some non-standard equipment and precision conveying, in order to minimize the impact of conveying processes, we prefer to use toothed synchronous belts, in combination with methods such as CCD detection. Machine-finished parts should be used as much as possible in the accessories, but this inadvertently increases manufacturing costs. 08. The use of standard components on assembly lines reduces costs but lowers precision. 09. Some measures to prevent deviation. Features such as drum-shaped rollers, flanges, rollers to limit the movement of the belt in all directions, and dynamic tension correction can help solve some problems. However, to address the root causes of these issues, a strong sense of quality is necessary, as well as solutions to improve processing accuracy. Belt deviation is the most common fault when a belt conveyor is in operation. To address such failures, special attention should be paid to the dimensional accuracy of installation and regular maintenance. There are various reasons for deviation, and different approaches need to be taken depending on the cause. 1. Adjust the idler roller set: When the belt of the conveyor deviates in the middle of the entire belt conveyor, the position of the idler roller set can be adjusted to correct this deviation ； During manufacturing, the holes on both sides of the idler roller set are machined as long holes to facilitate adjustment. The specific method is to determine which side the belt is biased to, and then move the corresponding side of the idler roller set forward in the direction of belt movement, or move the other side backward. If the belt deviates upward, the lower part of the idler roller set should move to the left, while the upper part should move to the right. 2. Installation of self-aligning idler sets: There are various types of self-aligning idler sets, such as those with a central shaft, four-link mechanisms, or vertical rollers. The principle behind them is to use barriers or idlers that prevent rotation in the horizontal plane, or to generate lateral forces that cause the belt to move toward the center, thereby correcting any misalignment of the belt. This method is generally more appropriate when the total length of the belt conveyor is short or when the conveyor operates in both directions, as shorter conveyors are more prone to deviation and are harder to adjust. However, this method is not recommended for long belt conveyors, as the use of self-aligning idler sets can have a certain impact on the service life of the belt. 3. Adjust the positions of the drive drum and the redirecting drum. The adjustment of these drums is an important part of correcting belt deviation. Since a belt conveyor has at least 2 to 5 idlers, the installation position of all these idlers must be perpendicular to the centerline along the length of the belt conveyor; if there is too much deviation, misalignment will inevitably occur. Its adjustment method is similar to that of the adjusting idler set. If the belt deviates to the right side of the drum, the bearing housing on the right side should be moved forward; if it deviates to the left side, the bearing housing on the left side should be moved forward. Conversely, the left bearing housing can also be moved backward, or the right bearing housing can be moved backward. The method of adjusting the tail roller is exactly the opposite of that for the head roller. Repeated adjustments were made until the belt was in an optimal position. It is best to accurately install the position of the drive or redirecting roller before making any adjustments to it. 4. Adjustment of the tensioning point – Adjusting the belt tensioning point is a very important aspect in correcting misalignment in belt conveyors. The two redirecting drums located above the weight tensioning point should not only be perpendicular to the length direction of the belt but also perpendicular to the line of gravity, thereby ensuring that their axis centers are horizontal. When using spiral tensioning or hydraulic cylinder tensioning, the two bearing seats of the tensioning drum should be translated simultaneously to ensure that the drum axis is perpendicular to the longitudinal direction of the belt. The specific method for adjusting belt deviation is similar to that used at the drum. 5. Adjustment of belt deviation in bidirectional belt conveyors: Adjusting belt deviation in bidirectional belt conveyors is much more difficult compared to that in unidirectional belt conveyors. When making adjustments, it is necessary to adjust one direction first and then the other. During adjustment, carefully observe the relationship between the belt’s movement direction and its tendency to deviate, making adjustments one by one. The focus should be on adjusting the drive drum and the redirecting drum, followed by adjusting the idler rollers and the material dropping point. It should also be noted that when vulcanizing the joints of the belt, the stress along the length direction of the belt’s cross-section should be even; when chain guides are used for traction, the stress on both sides should be as equal as possible.