Views:136 Author:Site Editor Publish Time: 2021-03-05 Origin:Site
In the design process of the drive through racking system, the standardization of the pallet unit products is first necessary to determine the size, stack height, and rated load of the pallet. Only then can the overall structure of the drive-in rack and the key dimensions such as the span, depth, layer spacing, and height of the storage unit be planned. Finally, design and review the shelf structure and parts.
When designing, design verification or test verification should be carried out for key parameters. Establish the corresponding simplified mechanical model according to the case structure, and according to the actual force (including seismic load, etc.) and load distribution of the shelf, combining the geometric parameters and quality characteristics of the corresponding component sections, design and check the strength, stiffness, and stability. If necessary, it can be verified by experiments to ensure that the design results are consistent with the actual situation.
Storage items, handling equipment, and the unitized size of pallets determine the structure and size of the drive in and drive through racking. Therefore, the first thing of planning and design of the drive-in rack warehouse is the standardization of the pallet unit goods. Due to the high storage density of the pallet unit of the drive-in rack, the operation channel and storage space are integrated. Compared with other types of racks, there are more detailed specifications and higher quality requirements for pallets and pallet units. The force characteristics of the pallet can be effectively selected. Especially for large-span pallets, it is necessary to check the static load and dynamic load of the pallet, the load on the shelf and the way of placing the goods on the pallet.
Pallet unitized goods should not be too large or heavy. Generally, the weight should be controlled within 1600KG, the pallet span should not be greater than 1.5 meters, and the storage items should be classified by unit packaging. At the same time, this type of shelf has relatively high requirements for the unitized packaging of goods to reduce the damage rate of stored items and improve the efficiency and safety of shipping. The structure and size of the shelf should be determined according to the storage items and the size of the pallet. Try to use the 1200 series pallets recommended in the national standard.
Due to the high storage density and high turnover efficiency of the drive in pallet racking storage area, the steel structure of the rack is close to the operation and storage channels. Try to store heavy-duty and large-storey goods in the lowest storage position of the drive-through racking structure, which can effectively reduce the storage center of gravity of the racking system and improve the storage and stability of the system.
On the basis of the above conditions, the overall layout and structural design of drive-in racks, as well as warehouse planning and design combined with other racks, can be further carried out.
The lattice column structure is the most common structure in the drive-in rack structure. Different from other types of shelf structures, the lattice column structure mainly bears lateral bending resistance. That is, the pallet unit goods are stored on the cantilever beam standing on the side of the lattice column structure. The self-weight of the goods and the shelf acting on the single and double-sided cantilever beams generates the cantilever moment, which is transmitted to the lattice column structure. The semi-rigid or rigid top beam structure is connected between adjacent column members to form a multi-door lattice type shelf. The column member body is connected with the cantilever, the cantilever beam or other parts through a mechanical locking device. The base of the shelf lattice column component is connected to the ground foundation by bolts or other forms.
The lattice column structure is mainly composed of column limbs (frame columns) and web members (transverse and diagonal braces). The column limbs are mostly single-axis symmetric cold-formed thin-walled porous section steel columns, and the web members are mostly cold-formed steel with C-sections. The column limbs and the web rods are connected by bolts to form a single oblique rod batten structure. The pressure of the frame column is slightly reduced due to the horizontal and diagonal bracing sharing part. When the beneficial effects of horizontal and diagonal bracing are not considered, the whole structure is safer.
The typical structure of the column limb is a uniaxial symmetric cold-formed thin-walled porous section steel column member. When bearing the load-bearing capacity of the cargo, it is prone to bending and torsion buckling, which reduces the load-bearing capacity. A patch panel can be added on one side of the opening to make it close to the closed cross section. Its bearing capacity can be greatly improved. The X-X bending stability of this type of component directly determines the load-bearing capacity and structural stability of the drive-in rack. Similarly, the lattice column structure is also a side column forming a drive-in rack door structure.
Because the flexural rigidity and torsion rigidity of the portal frame structural members are relatively small, the overall rigidity of the structure is relatively weak. Therefore, the higher the height of the portal frame structural member, the lower its load-bearing stability, and its ability to resist bending and torsion buckling will also be significantly reduced. The length parameters of the cantilever arm and the weight of the load-bearing pallet are the direct action bodies that exert the bending torque on the lattice column structure, and the additional bending torque generated with the length of the cantilever affects the bending and torsion resistance of the shelf column.
At present, when designing drive-in racks, the analysis of the system structure frame is replaced by the calculation of the strength, rigidity and stability of the lattice column of the rack. Since the lattice column is generally composed of relatively slender and thin components, the rigidity and stability of the column structure in the drive-in rack structure is greatly affected by its slenderness ratio. Its structural stability is weak, and there are few structural reinforcement modes that can be achieved, and it is difficult to achieve.
At present, the market uses WAP shuttle trolleys to replace the entry and exit operation mode of other handling equipment such as forklifts to optimize the operation channel. This can facilitate the horizontal beam tensioning of the frame column at the effective position below the storage location, which can greatly optimize the slenderness ratio of the frame column. Or at the innermost position of the entry and exit lanes, the design of the drive-in rack structure is optimized through the typical structure of the pallet beam rack, so as to improve the carrying capacity and stability of the rack structure as a whole. This will also become one of the main methods for the design and planning of drive in drive through racking system in the future.
Because the corresponding shelf vertical frame has the characteristics that are different from the solid web compression bar. When the lattice column is bent around the imaginary axis, it will cause additional deformation that cannot be ignored, and the bending rigidity of the lattice column is lower than the sum of the solid web compression rods (frame columns). When calculating the stability of the imaginary axis, the influence of shear force needs to be considered. This is also the basis for the drive through racking system structure to distinguish it from other rack structures.
At present, the main parameters such as the specification, height, thickness, cantilever length parameters of the portal column, and the weight and number of layers of the load-bearing pallet are used to determine the selection of the drive-in rack structure and size parameters. The structural design of the portal frame structure of the innermost cargo space of the aisle is the key to the design of the entire drive-in rack. The diagonal pull rod on the back directly determines the lateral restraint and restraining force between the shelf columns, and directly determines the stability of the system structure and the design and manufacturing cost of the shelf structure.
Read our article before entering the rack design, which is conducive to a deeper understanding of the drive-in racking design. Weixun is China's top 10 drive in and drive through racking manufacturer, providing professional drive through racking system. If you have any needs, please contact us!