What Are the Main Technical Requirements for Rising Bollards? - 翻译中...
In fact, the working process of the automatic lifting column is very simple. In one sentence, the actuator (movement) inside the column drives the column to rise and fall under the control of the control command. However, due to its extremely harsh working conditions and increasingly complex application requirements, the technical requirements for a qualified lifting column are still very high.
This index is the most important technical requirement of the driveway security bollard products. According to the protected object and the installation location, it is necessary to select the bollard product with the appropriate blocking capacity. For the evaluation of blocking ability, foreign standards are mostly measured by the maximum tolerable collision energy, which is rigorous but not intuitive.
Since the lifting column is buried below the ground, whether it can be immersed in water and operate normally is a very important rigidity requirement. Generally speaking, most of the internal drives have IP68 protection level and can be immersed in water, so the main structure of the lifting column does not need to have waterproof requirements.
However, if the actuator (movement) installed inside the lifting column does not have IP68 protection capability, the main structure of the automatic lifting column must be required to meet the IP68 waterproof level. It is neither economical nor durable to seal the interior of the main structure of the lifting column so that it has an IP68 protection level, so there are very few lifting column products with this design at present. This is because the lifting column is a cylindrical moving part with a diameter greater than 219mm. The lifting process will bring the gravel on the ground into the sealing gap. The hardness of the gravel is equivalent to that of diamond, which can damage any sealing material, thus making the sealing structure fail.
In order to cope with temperature changes throughout the year and the huge differences in climatic conditions in various geographical locations, lifting columns must be able to operate without failure in ambient temperatures ranging from -40°C to 65°C. Even if the operating performance of the lifting column is attenuated under low or high temperature conditions, it must not fail due to this, causing the equipment to fail and completely unable to operate, so that the control point is in a risky state of complete loss of management functions.
In various international standards and Chinese standards, there are no clear restrictions and requirements on the lifting speed. Based on practical application experience, the lifting speed is 2.5s-4s according to different column heights, and the descending speed is 2s-3s. If it exceeds this range, the user experience will be greatly deteriorated. When rising, if the speed is too fast, the surrounding people or people or non-motorized vehicles that happen to be at the upper end of the lifting column will not have time to react, and the risk of accidental injury will increase. When rising, if the speed is too slow, on the one hand, the risk of forced intrusion will be increased, and on the other hand, the flow capacity of the channel will be reduced. When falling, if the speed is too fast, the inertial force of the column will increase the impact on the overall structure. Long-term operation will reduce the service life of the product and increase the failure rate. When the driveway security bollard is lowered, if the speed is too slow, on the one hand, it will increase the risk of accidental collision of vehicles, and on the other hand, it will reduce the flow capacity of the channel.
When installing the lifting column, it is necessary to excavate below the ground, and the excavation depth varies with the product. Common sense can tell us that the shallower the excavation depth, the better, but the shallower the equipment cost, the higher the equipment cost, so a trade-off must be made between the construction cost and the equipment cost. Advantages of shallow burial:
(1) Low construction cost.
(2) Low construction risk.
(3) The late equipment maintenance of shallow buried equipment is easier than that of deep buried equipment, that is, the cost is lower.
Here, a misunderstanding of many people needs to be corrected: the deeper the equipment is buried, the stronger the impact resistance. To put it simply, if it is just a column standing on the ground, its impact resistance is roughly proportional to the depth below the ground within a certain value, but if it exceeds this depth, the relationship is very weak, and it is not related to this column. There is a direct relationship between yield strength and shear strength of a column. For a lifting column with a reasonable mechanical structure, the depth is only about 300mm-400mm.