AGVs use transfer devices to load and unload goods, that is, to accept and unload loads.
Common AGV loading and unloading methods: passive loading and unloading, active loading and unloading.
1. The passive loading and unloading trolley does not have a complete loading and unloading function, but adopts the auxiliary unloading method, that is, it is automatically loaded and unloaded with the loading and unloading device of the loading and unloading station or the receiving party.
Common unloading devices include roller table and lift table:
a. There is a hydraulic lifting mechanism under the lifting table using the lifting table, and the height can be adjusted freely. In order to transfer the load smoothly, the AGV must stop precisely to automatically exchange with the platform.
b. The environmental requirement of using a roller table is that the platform must have a power transmission roller table, the AGV is parked on the side of the platform, and the roller table on the AGV and the roller table on the platform are connected and act synchronously to realize the transfer of goods.
AGV Roller Table and Lift Table
(1) Push-pull type: AGV loading and unloading goods is realized through its own push-pull mechanism and an unpowered roller platform on the ground. During operation, the AGV is parked on the side of the platform, and the outrigger is pushed and pulled left and right by the push-pull mechanism to complete the loading and unloading of goods. The goods roll between the AGV roller table and the ground platform roller table, and the load transfer is ingenious. Signal and power transmission, suitable for handling occasions between platforms of the same height. However, the positioning accuracy of the operating point and the parts related to the transfer system are relatively high, especially in the case of multiple vehicles and multiple platforms, it is difficult to ensure its reliability.
The push-pull type is often used for material handling on flat pallets. If it is a European-style pallet or other objects, pay attention to meet the conditions of rolling and push-pull.
(2) Roller table type: AGV loading and unloading goods is realized after docking with its own roller table and the ground platform roller table. The ground platform is a roller table with power transmission. The AGV is accurately parked on the side of the ground platform. After the vehicle and the roller table on the platform are connected correctly, the synchronous transmission completes the transfer. Therefore, the rolling elements are required to be standardized, the transmission height is consistent, and the transmission speed is consistent. It can load and unload pallet goods in left and right directions, with high operation efficiency and good AGV safety. The transfer mechanism and principle are simple and reliable, but the platform needs to have chain signals and power transmission. It is suitable for the round-trip operation between the entry and exit RS/AS of the workshop or warehouse area with a small number of stations. The roller type is often used in the transfer of various kinds of pallets or objects that can be rolled, including large cartons, wooden boxes, plates, containers, etc. It is especially suitable for the handling of heavy-duty materials.
(3) Chain type: Except that the transmission mode of goods is different by chain or chain plate, the rest is similar to the roller type. The chain type is mainly suitable for transfer occasions where objects cannot be rolled.
(4) Belt type: Except that the conveying mode of the goods is different from the conveyor belt, the rest are similar to the roller type. The belt type is mainly suitable for the transfer of lighter and smaller materials, such as cartons, cartons, various bags, etc.
2. Active loading and unloading means that the automatic trolley itself has the loading and unloading function. Common active loading and unloading methods include single-sided push-pull, double-sided push-pull, forklift [Figure (a)] and robotic [Figure (b)].
AGV Active Transfer Method
(1) Traction type: AGV is used as traction power to complete the transportation of materials by towing a box or container with pulleys. It is suitable for occasions where buckets and trailers are used to transport materials, such as luggage transport, chemical transport, waste collection, etc.
(2) Piggyback type: AGV transfers materials by piggybacking. Generally, the transfer mechanism is located above the AGV body. During operation, the AGV stops directly under the goods, and the lifting mechanism is used to carry or lower the goods to realize the transfer of goods. Action Simple, efficient and safe. It is suitable for the round-trip transportation of various forms of goods and heavy objects, and can also be used as a flexible assembly line and processing line. It is often used for handling objects such as body, frame, container, and large machine parts.
(3) Fork type: Fork type AGV is basically similar in style to manual forklift, there are side fork type, forward fork type, floor fork type, three-way fork type and other models. Fork AGV basically uses pallets to stack goods for operation, and is currently developing rapidly with the gradual promotion of standard pallets in the logistics industry.
Side fork type: The goods are transferred from the left and right sides of the car. Because the center of gravity needs to be balanced by the car body during the forklifting process, the car body is relatively heavy, the transfer weight is limited, and the energy consumption is high and uneconomical.
(4) Forward fork type: Fork goods from the front of the car body, which can adapt to the operation occasions of various pallets from the ground to the conventional height range of shelves. The characteristic is that there is no outrigger under the fork, and the forklift body is completely outside the shelf or platform during operation, and there are no special requirements for the environment. However, due to the need for balance, the body is relatively heavy, the forks are protruding, and the safety is limited.
(5) Floor fork type: the fork is at the rear of the car body and can be lifted up and down. When it falls, it is above the two outriggers. The fork spacing is consistent with the two neutral positions under the standard European pallet, and it can just enter into it and lift the pallet. goods. Therefore, the transfer process can only be completed by reversing. For the double-sided pallet, it cannot be placed directly on the ground, but must be placed at a certain height (generally ≥100mm) to ensure that the fork and the two legs below can enter at the same time. This model is suitable for loading and unloading goods between platforms or shelves (corbel type) with large height difference, especially for the intensive storage and handling of drive-in aisles and multi-layer shelves (corbel type). The disadvantage is that there are outriggers under the fork, and the safety of the reversing process is limited. It is often used for automatic storage and handling of materials from various warehouse areas to workshops, such as automatic logistics systems for auxiliary materials, raw materials, and finished products.
(6) Three-way fork type: The forks of this AGV can automatically load and unload pallet goods in three directions: left, right, and straight ahead. Adapt to a variety of standard pallets, suitable for multi-layer shelves in roadways or storage and loading occasions with large height differences. The disadvantage is that the model is bulky and wide, the driving area takes up a lot of space, the effective utilization rate of the work site is low, and the AGV has a complex structure and high cost.
(7) Picking type: It is an automatic guided picking vehicle transformed on the basis of the traditional manual picking vehicle. When working, people only need to stand on the AGV picking table. After receiving the picking instruction, the AGV will automatically drive in the optimal order, stop at the target position accurately one by one, and lift the picking table to a height suitable for people to choose. You can follow the information prompts of the on-board terminal to pick, and then confirm the completion of the item, and then the AGV will go to the next target point, continue to pick the next item, and proceed in turn. It is often used in multi-variety small goods occasions in the aisle shelves in low-level flat warehouses, such as the selection of medicines, books, files, spare parts, etc.
(8) Gantry type: The AGV is similar in shape to the gantry structure, and can travel in all directions. The loading and unloading process is to complete the loading and unloading of goods by moving the forks and lifting and lowering laterally on the left and right sides. The operation flexibility is strong, and the driving safety is good. The requirements for the ground station are simple, but the transfer mechanism is complex, suitable for narrow areas or harsh paths. It is mostly used in the production workshop, such as the delivery of raw materials for food processing.
(9) Robot type: The AGV is equipped with a manipulator, which can automatically drive according to the instructions, stop accurately, and automatically complete a series of operation functions such as snatch, assembly, loading and unloading, stacking, and depalletizing. It is an intelligent mobile industrial robot. However, the structure and control are complex and the cost is high. It is often used in special conditions, high requirements, or some unmanned occasions, such as automatic matching of accessories, automatic grabbing of dangerous goods, etc.