As the main construction machinery for construction, tower cranes have been used extensively in building construction because of their high height and wide coverage. They are also responsible for the main vertical transportation work, and because of their high gravity, high risk, etc. Unpredictable safety accidents can occur, and serious accidents that can lead to machine crashes. Therefore, how to strengthen the safe use and management of tower cranes has attracted the attention of manufacturers, construction companies, and construction administrative departments. This article will use Minwei's actual production management for many years of experience in the use, management and testing of the tower crane crane safety use and management to do a simple discussion, and to make tower crane safety better.
1. Data Management Construction companies or tower crane owners should apply the tower crane's production license, product certification, disassembly and assembly license, operating instructions, electrical schematics, hydraulic system diagram, driver's operation certificate, tower crane foundation map, and geology Survey data, tower crane disassembly program, safety technology disclosure, main parts warranty book (steel wire rope, high-strength connecting bolts, anchor bolts, and major electrical components, etc.) were submitted to the tower crane testing center. After being tested by the tower crane testing center, Obtain the safety use certificate, transfer records with the project manager after installation, and strengthen the dynamic tracking management of the tower crane in daily use, and make a record of the shift, inspection records and maintenance records (including minor repairs, intermediate repairs). , major repair) and related responsible person signature, in the process of repairs in the replacement of materials and wearing parts should have a certificate of compliance or quality assurance, and the above materials in a timely manner filing, the establishment of a machine with a stand account.
2. The disassembly and assembly of the dismantling and managing tower crane is a frequent occurrence stage of accidents. The safety accident caused by improper dismantling and unqualified installation quality occupies a large proportion. The dismantling and installation of tower cranes must be carried out by qualified disassembly and assembly units, and they must be installed and dismantled within the scope of their qualifications. The disassembly and assembly personnel must go through specialized business training, have some experience in dismantling and installation, and hold certificates. At the same time, all types of work personnel are required to complete their duties, their positions are clear, they perform their duties, and they follow the unified command. In the process of debugging, professional electrician technology The level and sense of responsibility are very important. An electrician must hold an electrician's permit and a work permit. Special circumstances do require that there be sufficient lighting at night, and special circumstances do necessitate full consultation and agreement with the car driver on the procedures for disassembly and precautions during the night.
3. Tower crane The foundation of the tower crane is the basis of the tower crane. Practice has proved that many major safety accidents are caused by problems in the tower crane foundation. It is an important factor affecting the overall stability of the tower crane. Some accidents are due to the construction site to grab the construction period and install it rashly when the concrete strength is not enough. Some accidents are due to insufficient endurance, and some are due to excavation near the foundation and even landslides are displaced or due to accumulated water. Uneven settlement, etc., and the like, can cause serious safety accidents. We must pay great attention to it and we must not be vague. The stability of the tower crane is the ability of the tower crane to resist overturning. The biggest accident of the tower crane is dumping and collapse. When doing the foundation of the tower crane, it must be ensured that the endurance meets the design requirements, and the strength of the reinforced concrete should be at least 80% of the design value. The tower crane basement with basement engineering must take special measures: some of them should be piled under the foundation, and the steel reinforcement at the end of the tower be firmly welded to the foundation bolts. The bottom of the concrete foundation should be smooth and compact, and the bottom of the foundation should not be made like a pot bottom. The foundation foot bolt size error must be constructed strictly in accordance with the requirements of the foundation drawing. The anchor bolts must maintain a sufficient length to expose the ground, and each anchor bolt must be pre-tightened by double nuts. The basic surface should be treated before installation to ensure that the level of the foundation cannot exceed 1/1000. At the same time, the base of the tower crane must not collect water. The accumulated water can cause uneven settlement of the tower crane foundation. No digging or ditching shall be allowed in the vicinity of the base of the tower crane.
4, safety distance from the tower crane in the layout of the plan to draw plans, especially the real estate development community, residential buildings, tower cranes, such as forests, but also to consider the safety distance of adjacent tower cranes, in both horizontal and vertical direction must guarantee not With a safety distance of less than 2m, the tower body and the boom of adjacent tower cranes must not interfere with each other. Try to ensure that the tower crane can rotate freely when the wind is too strong. The safe distance between the tower crane's rear arm and adjacent buildings is not less than 50cm. The safe distance between the tower crane and the transmission line meets the requirements. The safety distance between the tower crane and the transmission line is not enough. Table 1 requires a protective frame to be erected on the tower. In principle, the protection frame must be installed and installed without metal materials. Bamboo rafts and other materials can be used. The distance between the bamboo raft and the power transmission line should not be less than 1m but also have a certain degree of stability to prevent the strong wind from falling. In order to ensure that the above safety distances meet the regulatory requirements, especially in the construction of large-scale residential communities, we focus our work on the safety inspection in peacetime. When the project is started, the construction company is required to set the general level of on-site construction machinery. After a reasonable arrangement, we will report it to us. If the construction companies do not coordinate well with each other, we will notify the construction unit to coordinate.
5. Safety devices In order to ensure the normal and safe use of the tower cranes, we must obligate the tower cranes to have the required safety devices when they are installed. The main ones are: lifting torque limiter, lifting weight limiter, height limiter, amplitude Limiters, rotary limiters, hook safety devices, reel safety devices, wind anemometers, wire rope escape insurance, trolley breakage prevention devices, trolley break prevention devices and buffers. These safety devices are to ensure its integrity and sensitivity. If it is found to be damaged during use, it shall be promptly repaired and replaced, and shall not be released or arbitrarily adjusted.
6, the stability tower crane height and bottom support ratio is large, and the tower body's high center of gravity, large torque, frequent braking, impact force, in order to increase its stability, we must analyze the tower crane overturning The main reasons are the following: First, overload. Different types of cranes usually use lifting torque as the main control. When the working range is increased or the weight exceeds the corresponding rated load, the overturning moment of the weight exceeds its stable torque, which may cause the tower crane to collapse. Second, oblique hanging. When tilting a heavy object, it will increase its overturning moment. At the lifting point, horizontal and vertical component forces will be generated. At the bottom of the tower crane, an additional overturning moment will be generated at the supporting point, thereby reducing the stability factor and causing the tower crane to collapse. Third, the foundation of the tower crane is uneven and the ground endurance is not enough. Excessive verticality error may also cause the tower crane's overturning moment to increase, which will reduce the stability of the tower crane. Therefore, we must proceed from these key factors to strictly inspect inspections and prevent major equipment accidents.
7. Electrical safety In accordance with the requirements of "Safety Inspection Standards for Building Construction" (JGJ59-99), special switch boxes for tower cranes must also meet the requirements of "one machine, one brake, one leakage, one box," and the tripping rated operating current of the leakage protector shall be Not more than 30mA, the rated operating time does not exceed. The switchboard in the cab must not be exposed. The electrical cabinet should be intact, closed tightly, and the door should be fully locked. The electrical components in the cabinet should be intact, the circuit should be clear, the operation control mechanism should be sensitive and reliable, and the limit switches should be well-functioning. Professional electricians should be regularly checked for maintenance.
