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Because of the particularity and structure of tower crane, its safety lies in the installation, use, management, natural environment and many other factors.

(1) the tower crane's own structure because of the cable

The stiffness, stability and strength of the steel structure of the tower crane directly affect the safety of the tower crane. Due to the frequent alternating load of the crane in the operation process, it is easy to make the steel structure fatigue broken maple. Such as the tower crane girth weld cracking, base metal fracture, deformation, bending, etc., so that the structure of the stiffness, stability, strength reduction, so that the steel structure of the thin labor damage, damage the local stability of the steel structure. A friend accident.

(2) The electrical system, the mechanism and the element.

The working mechanism of tower crane adopts electrical operation and control, which has the advantages of convenient control, saving Nuo and low cost. At the same time, electrical components are easy to achieve standardization and generalization, easy to replace, easy to achieve a variety of safety protection. The working condition of the mechanism electrical system determines the reliability, safety and performance of the tower crane. If there is damage and abnormal. This can lead to accidents. Such as electrical system failure, can cause the mechanism to produce shock vibration, resulting in broken shaft, broken teeth and lead friends accident. Clutch and brake damage or vehicle control may cause crash and heavy objects. Electrical insulation aging or cabinet damage may lead to electric shock accident. Failure of various safety devices may lead to accidents such as falling towers, folding arms and heavy objects. If the amplitude limit or stroke limit fails, it may cause the cart or trolley to rush and even derail. Overload limiter and torque limiter failure, possible folding arm and tower fall accident.

Failure of the height limiter may lead to over-rolling of the wire rope, breaking of the wire rope and falling of heavy objects. Phase sequence protection vector rescue, in the case of misphase and phase failure. Operation instructions may be disordered to cause accidents.

(3) Human factors

In many tower crane accidents. Most of the accidents are due to the user's illegal operation or misoperation. The two accidents mentioned below also have the factor of illegal operation.

A non-driver of a unit does not ring the bell to drive. As a result, the workers who were performing dimensional extravagance on the track were crushed. When the installation team of a machinery construction company inspected the TQSOB tower crane, in order to replace the lifting arm pull pin, it was prepared to remove the balance weight first and then replace the pull plate pin, connect the lifting arm with the lifting rope, and then lift the lifting arm by car. Open the boom pull plate pin, when the boom is lowered, the backward tilting moment generated by the balance weight is very large, which causes the tower crane to lose balance and causes the balance arm to fall together with the tower tip.

Disassembly process accident. Due to the high weight of the metal structure of the tower body, the disassembly and assembly of the tower crane is a high-altitude operation, which is dangerous and highly technical. In the tower crane accidents, the accidents occurred in the process of disassembly and assembly account for a large proportion, and they are relatively large accidents. Some tower crane disassembly and assembly is not done by professional installation teams but by non-professionals. Due to the low quality of the installation personnel, the lack of the ability to prepare the installation plan, the lack of the ability to select the plan and calculate the mechanics, and the lack of the ability to formulate scientific disassembly and assembly, new problems or special problems in the operation process cannot be solved and accidents occur.

Therefore, it is inevitable. Some installation quality is not standard, leaving the accident hidden danger.

Mismanagement. Insufficient training of staff by competent units and safety departments, insufficient understanding and implementation of various rules and regulations, and insufficient management of work sites have laid hidden dangers for accidents. Some enterprise system is not perfect, the staff has no rules to follow, had to rely on personal experience to carry out the operation, easy to make mistakes. Therefore, the driver may make mistakes in operation. In some construction sites, some staff members are temporarily combined to work in order to meet the needs of the work, making it difficult for the commanders, drivers and department personnel to achieve the work.

Industry coordination, some non-professional personnel or leaders temporarily act as operators, inevitably errors and accidents; Some enterprises do not pay attention to maintenance management and fail to nip the hidden dangers of accidents in the bud.

(4) Natural causes

The so-called natural cause of ugliness refers to people's failure to see and sudden harm to Gonso, not to be transferred by human will, some are irresistible disasters. Like earthquakes, floods, typhoons. Can be mu connected or indirectly caused by Guangdong. For example, in the manufacturing process of tower crane, the residual internal stress of the structural parts is too large, and the local stress of the structure under the action of external force in the use of stress concentration increases sharply, resulting in sudden fracture of the components, resulting in accidents, which is also unpredictable for users. There are also tower cranes made of ordinary structural steel operating below minus 20 ℃, which will produce brittle fracture and lead to stress.

Component broken. The power supply voltage of the power grid is too low and the system voltage drop is too large, which causes the electrical control failure and causes the accident caused by the out-of-control mechanism.

There are other factors that can also cause accidents, such as insufficient safety distance between the tower crane and the high-voltage line or adjacent buildings, which can lead to electric shock or collision accidents.

Tower crane foundation pressure is not enough, can lead to foundation instability, causing the tower fall accident.

Unreasonable strapping or unfavorable suspension of hanging objects will lead to heavy objects falling accident. The safety protection measures of the guard ring, guardrail and safety platform of the tower crane do not meet the requirements, which may cause personnel falling accident. The above factors are the causes of the accident. Only by operating in accordance with the regulations and strengthening the maintenance of equipment can we eliminate hidden dangers and ensure safe production.