In the core components of a drum conveyor, the drum, as a cylindrical component responsible for material conveying, is divided into two types: driving rollers and driven rollers. It is widely used in circular screen printing machines, digital printers, logistics conveyors, papermaking equipment, and other scenarios. The material selection and structural design directly affect the stability of equipment operation, and the diameter selection and thickness calculation of the drum are key factors in adapting to different conveying needs and ensuring equipment durability.
1、 Drum diameter: selected as needed to balance the stress of the conveyor belt
a. Common diameter specifications
The diameter of the drum needs to be matched with the conveying scenario. The mainstream standard specifications in the industry include 25 mm, 32 mm, 38 mm, 42 mm, 50 mm, 57 mm, 60 mm, 76 mm, 80 mm, and 89 mm, which can cover different needs from small automated assembly lines (such as electronic component conveying) to medium and large material transfer (such as luggage and parts conveying).
b. Core principle of selection: adapt to the stress of the conveyor belt
The core logic of diameter selection is to balance the tensile stress and bending stress of the conveyor belt.
① When the tensile stress of the circular conveyor belt is high (such as when transporting heavy materials or long-distance transportation causing high tension on the tape), it is necessary to reduce the additional bending stress of the conveyor belt by increasing the diameter of the drum to avoid fatigue damage to the tape due to repeated bending;
② If the tensile stress of the conveyor belt is small (such as light load conveying, short distance conveying), it is allowed to withstand slightly larger bending stress, and smaller diameter rollers can be used to save equipment installation space and reduce costs.
2、 Drum thickness: determined by multiple factors, balancing strength and practicality
a. Key variables affecting thickness
The thickness of the drum shell is not a fixed value and needs to be calculated and determined based on the following factors:
① Basic parameters: diameter of the drum itself, length of the drum body (the longer the length, the thicker the shell needs to be to avoid deformation);
② Load conditions: tension of the transport tape (the greater the tension, the more concentrated the force on the cylinder shell), wear intensity during braking (frequent braking will exacerbate cylinder shell wear and require thickening to extend its lifespan);
③ Material characteristics: If different materials such as carbon steel and stainless steel are used, the required thickness under the same working conditions will also vary due to differences in tensile strength and wear resistance of the materials (for example, stainless steel material can be appropriately thinned, while carbon steel needs to be thickened to prevent rust and wear).
b. Practical application logic of thickness calculation
Due to the complex stress on the cylinder shell (which simultaneously bears normal and tangential loads, and the load dynamically changes along the circumferential direction), there is currently no fully accurate universal calculation method. In practical operation, the following principles should be followed:
① To avoid the problem of “theoretical calculation values being too small”: considering the characteristics of wear resistance and easy processing of the cylinder shell, the actual selected thickness is usually thicker than the theoretical calculation value, leaving a certain safety margin;
② Strength verification and finite element assistance: After determining the thickness, it is necessary to verify the strength of the cylinder shell. If high precision is required (such as heavy load and high-speed conveying scenarios), stress distribution data can be obtained through finite element analysis – it should be noted that there is currently a lack of specialized drum calculation universal programs, which can only be customized for a single specific drum for analysis;
③ Stress concentration area: When the shell is paired with soft web plates (used for buffering load in web plate structures), the maximum stress is usually concentrated in the middle of the shell length and outside the shell thickness. The thickness design of this area needs to be strengthened, and the stress can generally be estimated using approximate numerical methods to ensure that the strength requirements are met.
3、The Enhancement of Performance by Roller Material and Production Process
The design of diameter and thickness should be comprehensively considered in conjunction with the drum material and production process.
a. Material selection: carbon steel (galvanized, chrome plated, coated with adhesive to enhance rust and wear resistance), aluminum alloy (lightweight, suitable for light load scenarios), stainless steel (304 L/316, suitable for food, medicine and other hygiene scenarios), ABS (plastic material, suitable for anti scratch requirements of electronic components, etc.);
b. Production process: The conventional process is “initial rolling of the roller body → initial static balance calibration → shaft head welding → precision turning → precision dynamic balance calibration”. If the form and position tolerance (roundness, cylindricity, etc.) is required to be ≤ 0.2mm, an external cylindrical grinder grinding process needs to be added; When there is a requirement for surface hardness, additional heat treatment (such as quenching) is needed to further ensure the stability of the drum during long-term use.
