Cần trục giàn nhiệt độ cực thấp được thiết kế riêng cho mùa đông khắc nghiệt tại cảng Krasnodar: Giải pháp thiết kế tiên tiến

Our client purchased an ultra-low temperature gantry cranes for Krasnodar Port in southern Russia, which experiences harsh winters due to its high latitude in Siberian. To ensure the crane operates at temperatures as low as 40°C, special considerations were made when designing and selecting steel structures, mechanical components, and electrical systems. A dedicated team of experienced designers and engineers was formed, working closely with Russian counterparts on process design and equipment selection to meet specific environmental challenges.

The cold environment in high-latitude areas has a huge impact on the performance of cần trục của giàn cần cẩu, and necessary measures should be taken to deal with the low-temperature environment, including the impact of extremely cold weather on the operating effect and reliability of gantry cranes. According to the traditional structure type, the design and manufacture of gantry cranes can not meet the special requirements of the use of high-latitude areas, the need to seek a new special design structure, a new design theory, and process methods.

Ultra-low temperature gantry cranes problems

When the ambient temperature is lower than -20°C, the strength of the steel usually used will be greatly reduced, while the brittleness increases. This seriously weakens the steel’s normal mechanical properties, and the steel structure’s shrinkage and deformation can cause structural failure.

In a low-temperature environment, wires and cables also become stiff or even break. The lubricating oil becomes thicker, and braking wheels, wire ropes, wheels, and rails are subject to the erosion of ice and snow. Additionally, electrical components and various protective devices are prone to work abnormally or fail completely, preventing the gantry crane from operating normally.

Therefore, the development and research of ultra-low temperature gantry cranes is imperative.

Design characteristics of ultra-low temperature gantry cranes

To ensure that the gantry crane can work normally in a low-temperature environment, it is necessary to solve four problems: one is the design of the brittleness of the materials in a low-temperature environment; the second is the reliability protection of the transmission mechanism in a low-temperature environment; the third is the heating and heat preservation measures of the electrical components in a low-temperature environment; and the fourth is the release of internal stresses in the gantry crane caused by wide-ranging changes in temperature. According to the main impact of a low-temperature environment on the gantry crane, the design should fully consider the following five aspects.

1. Anti-brittleness study of steel structure in the low-temperature environment

The portal crane structure belongs to a typical box beam or truss beam steel structure, experiment proves that when the ambient temperature is below -20C, the brittleness resistance of steel structure decreases rapidly with the drop of working temperature by square proportionality, so the brittleness resistance design and strength design of steel structure are equally important in a low-temperature environment.

It is proved by studying many destructive instances that the parts of the steel structure that undergo brittle damage under low-temperature environments mostly occur at the stress concentration caused by improper design or processing technology, including weld intersections, sharp corners, openings, and cross-section mutations. These parts of the larger stress are likely to cause brittle cracking and lead to failure of the mechanical properties of the steel structure. For this reason, Henan Kuangshan Crane in the design of the steel structure took the following measures to deal with the impact of a low-temperature environment on the steel structure.

(1) The use of low-temperature resistant materials, such as Q345E structural steel, low-temperature stability, and low brittle cracking.

(2) Structural design should try to use rounded transition; when the structure must be opened, should not have sharp or curvature of the hole corners, measures should be taken to strengthen the peripheral strength of the hole, that is, the use of “ring” type of structural design.

(3) The cross-section of box-type beam members should not be changed abruptly, and a certain length of transition section should be retained so that the stress can be changed gently.

(4) The arrangement should not be overlapped and staggered, but should be appropriately dispersed; to try to ensure that the weld and the welded structure can be free of deformation; should not be used to concentrate the stress is more serious asymmetric unilateral lap weld, as far as possible, the use of butt joints.

2. Protection of transmission mechanism in the low-temperature environment

The transmission mechanism of the ultra-low temperature gantry cranes is mainly the hoisting mechanism and the operating mechanism of the two parts, consisting of a series of parts made of different materials such as motors, reducers, couplings, drive shafts, brakes, wheelsets, and so on. These parts have different destructive tendencies in the low-temperature environment, Henan Kuangshan Crane uses the following measures to cope with:

(1) Try to use the integrated transmission structure to reduce the transmission link, and reduce the transmission of parts required, while the integrated structure occupies a small space, is easy to install, and carries out a variety of protection.

(2) Through a reasonable design structure layout, the use of thermal insulation type protective cover is used to protect the main transmission device. Through the closed design layout of the lifting trolley into a closed structure, the use of thermal insulation materials closed and then installed inside the trolley temperature detection device, when the ambient temperature is lower than a set temperature value, the automatic start of the heating device. The internal temperature of the trolley is effectively controlled in a suitable range, eliminating the impact of a low-temperature environment on the operation of the trolley.

(3) For part of the transmission parts that are difficult to protect, in addition to the need for a low-temperature environment, material brittleness mechanics test, but also in the lubricant selection, reduce the impact of the operation to take measures. Ultra-low temperature gantry cranes should adopt soft-start motors, and PLC + frequency converter control, so that the overall operation is smooth and stable, reducing the impact load in the operation start-up process

(4) The use of low-temperature resistant materials such as Q345E steel, etc., should be tested for mechanical properties in low-temperature environments(-45C) before use. For enterprises in a position to do so, the main raw materials should be carried out in a low-temperature environment test, but also for welding process evaluation, especially -45C temperature of the weld, weld metal process evaluation, and mechanical properties testing.

3. Preheating and insulation of electrical components in a low-temperature environment

Normal working temperature of electrical components is generally 0C ~ 40C, too high or too low temperature will have a greater impact on electrical components. According to statistics, when the temperature is lower than the normal temperature of 10C, PLC, frequency converter, and other control components, the reliability of the control components will decline by 25%. To ensure that the electrical control system works properly, Henan Kuangshan Crane takes the following measures:

(1) Ultra-low temperature gantry cranes should be set up to insulate the electrical room, the electrical components will be installed in it, and the electrical room will be installed with a heating device. When the ambient temperature is lower than -20C, the ultra-low temperature gantry cranes should be preheated when it starts to work in the electrical room, and then start normal work after reaching the room temperature environment.

(2) The power supply cable adopts rubber cable which is resistant to low-temperature environments and ultraviolet radiation instead of PVC cable to prolong the service life of the cable under low-temperature environments.

(3) The motors of the hoisting mechanism and running mechanism are equipped with heaters to preheat before working in a low-temperature environment and keep warm after working; for ultra-low temperature gantry cranes used outdoors, the protection level of the motors is not less than IP66.

(4) Electrical components that can not be installed in the insulated electrical room should be installed in the electrical box with a protection level of not less than IP55, and the electrical box should also be equipped with a heating and insulation device.

4. Internal stress release of gantry crane structure caused by a wide range of temperature change

High latitude areas in winter and summer ambient temperature huge temperature differences will cause thermal expansion and contraction of the material, the steel structure of the large-span gantry crane will have a huge impact on the Henan Kuangshan Crane to use the appropriate measures to deal with the structure with the temperature changes caused by the internal stress changes in the structure.

First of all, the steel structure should be designed with a symmetrical structure with uniform cross-section changes, so that the deformation of the entire structure with temperature changes can be controlled.

Secondly, the steel structure should adopt a static structure design as much as possible, together with the use of an adjustable ball-hinge bearing, which can eliminate the internal stress caused by the deformation of the steel structure. It should be noted that the use of a static structure will reduce the rigidity of the entire structure, which is prone to ultra-low temperature gantry cranes runoff, gnawing rails, and other phenomena, so it is necessary to ensure the stable operation of the ultra-low temperature gantry cranes through the use of electrical deskewing, the setting of horizontal guide wheels and other measures.

5. Safety design

Crane hoisting mechanism through the use of “constant temperature” characteristics of the closed structure design; trolley running mechanism should use the three-in-one drive, that is, the motor, reducer, brake integrated running mechanism, and the use of hoof-type braking, the selection of low-temperature resistant lubricants.

Ultra-low temperature gantry cranes are used outdoors, Henan Kuangshan Crane designed a track heating device and snow scraping mechanism, to avoid excessive snow, track icing, and slipping, affecting the safe use of cranes.

Summarize

The design of ultra-low temperature gantry cranes needs to consider the use of new materials, new technologies, and new techniques for innovative development. Henan Kuangshan Crane for the successful development and application of Russia’s Krasnodar port gantry crane project, to promote the innovation of ultra-low temperature gantry cranes has played a positive role, especially for the extremely cold state of the ultra-low temperature gantry cranes steel structure and electrical reliability and other technologies have accumulated data and experience. The main technical achievements can also be applied to the design of products used in other special geographic areas.

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