As automation continues to advance, conveying equipment has become widely used in automated warehousing and logistics systems. Conveying equipment can be categorized into chain conveyors, belt conveyors, pneumatic conveyors, and screw conveyors based on the type of main working components. Among these, chain conveyors are the most diverse and widely used.

1 driver unit
Chain conveyor systems typically operate at low speeds but generate significant torque and power. Therefore, the drive system usually consists of a motor and a speed reduction unit. The drive shaft is rotated by the drive system to operate the conveyor chain and transport materials. The support for the drive shaft typically uses double-row self-aligning ball bearings (except for angle-driven suspended conveyors). These bearings automatically realign, ensuring the conveyor operates smoothly even with some coaxiality errors between the supports, and the double-row bearings provide sufficient load-bearing capacity. The main shaft is connected to the sprocket using a key connection. Additionally, the drive system must include safety protection devices. Traditionally, these devices used safety pins that would break under overload, but this process was time-consuming and labor-intensive. A more advanced safety protection device now uses an elastic base with an electrical limit switch. When the output torque of the reducer exceeds the load capacity, the elastic base triggers the limit switch, which promptly cuts off power to the main motor. Once the fault is resolved, the device can automatically reset. If the equipment is long and the load is heavy, using a single drive system can cause excessive chain tension. In such cases, an auxiliary drive system can be installed in the middle of the equipment, connected to the main drive system via a hydraulic coupling. The auxiliary drive system activates when the load exceeds the capacity of the main drive system and stops automatically when the load is within the main drive system's capacity. Due to the differences in motor characteristics, it is impossible to ensure that the two motors have exactly the same speed. Therefore, it is essential not to design the two drive units to operate simultaneously for extended periods, as this could result in different output speeds and additional tension on the chain (for example, long-distance suspended conveyors often use this structure). When designing the drive unit, it is necessary to calculate the traction force, torque, and power, and select the appropriate motors, reducers, frequency converters, chains, support bearing seats, drive shafts, and safety protection devices based on these calculations.

tightener

Chain conveyor systems use chains as the primary load-bearing components. Due to the significant allowable length tolerance of chains, wear during operation can cause the chain pitch to extend. Therefore, it is essential to design a tensioning device for these systems. The tensioning stroke of the device depends on the working chain pitch and the conveyor line length. The principle of designing the tensioning amount is to accommodate the chain length tolerance and the allowable chain wear extension, ensuring that after the two sections of the chain are replaced due to wear, the conveyor system can continue to function normally, thereby extending its service life. Tensioning devices come in various forms, including spiral tensioning structures (such as flat or scale plate conveyors), spring tensioning mechanisms, and heavy hammer tensioning mechanisms (such as suspended conveyors). Given the high tension forces typically experienced by chains in conveyor systems, when using spiral tensioning structures, it is crucial to ensure that the tensioning screw bears compressive stress rather than tensile stress, to meet the requirements for strength and stiffness, especially when the shaft support seat of the tensioning mechanism is made of cast iron.

The shaft is typically supported by a double-row self-aligning ball bearing with a sliding seat. This bearing housing design allows the shaft to move on the tension track, meeting the tension requirements. Additionally, the self-aligning bearing ensures that the conveying machine operates normally even when there is a certain amount of coaxiality error between the two supports.

When the conveying equipment uses a dual-chain or more chain structure, the chain lengths cannot be exactly the same. Therefore, the sprocket on the driven shaft must not be connected to the shaft using a key connection but should be allowed to slide along the shaft to reduce the additional tension on the chains.

The main part of the conveying line is typically constructed from welded section steel. In chain conveying equipment, the chains serve as the primary working components and the load-bearing body. Since the chains are flexible, they must be supported by a support track to ensure they function as a rigid structure. When there is slack in the lower chain of the structure, the chains have considerable weight. To reduce the slack tension, extend the service life of the chains, and minimize the power capacity of the drive mechanism, and to prevent interference between the chains and the frame during operation, a support track must also be designed for the slack. The support track is often made of wear-resistant and wear-reducing materials with sufficient strength. Due to the polygonal effect of chain drives, when chain drives need to be used sequentially in the structure (such as in a power roller line), the number of teeth on the sprockets between each stage should be the same to ensure a 1:1 transmission ratio, thus preventing crawling. When the equipment is composed of two devices with similar structures, each device should be driven by its own drive mechanism. Avoid using a single drive mechanism for both devices to prevent the chain's polygonal effect from causing noticeable crawling during operation (for example, in bridge-type automobile assembly lines, the high and low lines are each driven by their own mechanisms).

To accommodate different production rhythms, the conveying equipment can be designed to operate in either synchronous or asynchronous modes. Synchronous mode means that the conveying equipment operates at a fixed speed within a specific range, following a set rhythm; asynchronous mode allows the workpieces on the conveying line to stop and reset according to the station requirements. When the conveying method is asynchronous, the stop and release devices can vary in structure, which can be purely mechanical, pneumatic or hydraulic, or electrically controlled. Regardless of the structural form, the design must be reasonable, reliable, and meet the requirements of the product assembly process, making it a key challenge and core technology in conveying equipment design. 4 Selection of Chain Specifications For precision roller chains, national standards specify the power curve. During design, refer to the mechanical design manual to select the chain specifications based on the operating speed and the power transmitted by the chain according to the power curve. For other types of chains, the selection of specifications is still based on empirical comparison. The general principle for selecting chain specifications is that the breaking load of the chain should be 5 to 7 times the calculated usage load, and for suspended chains, it should be 7 to 10 times. 5 Electrical Control In electrical control, for simpler synchronous conveyors, conventional electrical control is typically used. The main control functions include speed adjustment, drive protection, overload protection, and limit protection. For non-synchronous conveyors, PLCs are generally used for process control.

When the system includes functions such as system grouping, address recognition, transmission, protection, and monitoring, which increase the number of control points, computer control is preferred. When a workshop has multiple conveying devices forming an automated production line, the control becomes more complex than with non-synchronous conveying equipment. Besides conveying workpieces, it also involves various management functions, and a central computer control system is usually adopted. In summary, the control system of chain conveyors should be tailored to the specific working conditions of the conveyor. Chain conveying equipment comes in various forms, each with its own unique characteristics. The control system must adapt to the assembly line's functions, which is the primary technical challenge. The design and selection of components such as reducers, motors, chains, and bearing seats, along with the strength verification calculations of the main and driven shafts, are key tasks during the design phase. The drive device, driven device, and the main structure of the conveying line form the core of the conveying equipment, while the chain is a critical component of the assembly line.