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Technical analysis of a bridge crane crush injury accident

1 accident profile

the accident occurred in the papermaking workshop of a paper company. There were two people at the scene of the accident, one of whom was the crane operator and the other was the dead. When the crane operator hoisted the paper reel and adjusted it to be in place with the swivel support, the suspended paper reel suddenly moved laterally in the direction of fixing the paper reel, squeezing the other person who was at the middle of the two paper reels to death

2 basic information of accident bridge crane

(1) the double girder bridge crane has a span of 13.5 m, a total rated lifting mass of 10/3.2 T, a crane running speed of 20 m/min, and a main lifting speed of 6.1 M/mm. The date of delivery: January 22, 2004. After installation, the crane has been accepted by relevant departments and is within the validity period of qualification

(2) the crane was originally operated by the ground, but the wired manual operation and wireless remote control can be switched by the user. Due to the failure of the conversion device, the interlock between the two control modes cannot be realized, and the local and wired manual operation device has been placed on the bridge. The model of the wireless remote control device is Apollo cl-10pb, the use frequency is

68.060 MH, the channel interval is 50 kHz, and the transmission power is 1 MW

3 on-site inspection of the accident

the personnel were crushed and died. Therefore, we determined the focus of the accident investigation

as follows:

3.1 analysis of the injury accident of the crane

according to the information provided by the relevant personnel of the factory, before the accident, the company wanted to place the paper reel lifted by the crane on the slewing support. At this time, the rotating shaft of the lifted paper reel and the slewing fixed support were not fully connected, It is in a semi separated state

when the crane cart operating mechanism continues to move towards the side of the fixed paper reel, the crane cart lifting center line deviates from the center of gravity of the paper reel by a certain distance, and then the lifting paper reel will be affected by a horizontal component e towards the direction of the fixed paper reel (this direction is the dangerous direction of accidents, if in the opposite direction, there will be no accidents), When the horizontal component I fails to overcome the friction resistance between the rotating shaft of the lifting reel and the rotating fixed support, the weight is in a static state

when the crane cart operating mechanism continues to move towards the fixed reel side, the horizontal component E increases gradually. When it increases to overcome the friction resistance between the lifting reel rotating shaft and the rotary fixed support, the lifting reel rotating shaft and the rotary fixed support will be separated. Under the action of e force, the lifting reel quickly swings towards the fixed reel side and collides with the fixed reel, resulting in an accident

according to the information provided by the relevant personnel of the factory, after the accident, the distance between the lifting center line of the crane cart and the center line of the rotary fixed support is about 2 m, and the minimum distance between the paper reels on the two rotary fixed supports is about 0.4 M

therefore, it can be determined that when the crane cart operating mechanism continues to move towards the side of the fixed reel, and the lifting reel rotating shaft is separated from the rotating fixed support, the lifting reel will collide with the fixed reel, resulting in an accident

3.2 whether the crane crane traveling mechanism will move in vain under non-human operation

there are two kinds of


first, whether the crane traveling mechanism will slide in vain when lifting heavy objects and standing:

Second, whether the crane control device will move in vain

for this reason, we have carried out the following tests on the crane running brake and the operation equipment. Ganfeng lithium 1 has been committed to the comprehensive recycling and utilization of lithium resources:

(1) inspection of crane running brake. The basic situation of brake on-site inspection is that the crane adopts double drive devices for crane operation, and there is a set of brakes on both sides

one is the South brake, which can rotate by pulling the brake wheel by hand. Measure the gap between the brake wheel and the brake pad with a feeler gauge in the static state. The maximum gap is about 1.5 mm. Most of the brake wheel surface has no friction marks during braking, indicating that the brake is improperly adjusted

the second is the North brake. After inspection, the components of each mechanism are in good condition, the braking is good, and the adjustment is appropriate

(2) lift the heavy object, stand still, and check whether the crane running mechanism can slip in vain. The weight loaded during the lifting accident - the paper reel, with a total mass of about 3 T, operates at the same position when the accident occurs and the test report meeting the standard requirements is output, and stops_ 1. Do not move, record the initial position of the load at this time and record the time, and check whether the load will move horizontally after a certain time

the interval is: 5 min, 10 min, 15 min, 20 min:

the horizontal displacement of the weight relative to the initial position is: 3 mm, 5 mm,

5 mm, 5 mm

(3) when the crane is running at a steady speed, the braking distance shall be measured for three consecutive times within the range of

3 m in the operation area when the contactor is disconnected, and the average value shall be taken

crane running distance: 3 m, 1 m, 0.5 m

average braking distance: 850 mltl, 750mm, 653mm

from the above results, it can be seen that when the heavy object is lifted and standing, the crane running mechanism will not slip in vain; When the crane runs and stops, there is a certain braking distance

3.3 on site inspection of crane control device

the original control mode of the crane was ground and wired manual control, and then Fang Baixing was replaced with wireless remote control mode. Both control devices can control the crane's crane operation, main lifting, auxiliary lifting and trolley travel mechanism. The test results are:

(1) when the crane is operated by remote control or wired manual control device at the same time, the interlock between them cannot be realized, and the emergency stop switch of wired manual control device fails. When the emergency stop switch of wired manual control device is pressed, the crane can still carry out various operations: but when an accident occurs, the wired manual control device has been placed in the main beam aisle of the bridge crane, and no one is on it, Therefore, the possibility of human misoperation of the wired manual control device is ruled out

(2) the possibility of non-human misoperation of the wireless remote control device:

first, after testing, the instructions of the wireless remote control device show that it has the ability to resist the same frequency interference signals, and when the accident occurs, the remote control with very flexible stock and supply advantages is not installed in the same workshop area, and there is no interference of lightning strong electromagnetic field:

second, The operation buttons of the wireless remote control device have been tested repeatedly at multiple stations on the site. Their action is sensitive and reliable, and their return is not normal. When the emergency stop key is pressed and the power supply is unplugged, all mechanisms of the crane cannot be started

from this, it can be determined that under field conditions, the wireless remote control device is unlikely to have non-human misoperation

4 the new reactor is scheduled to be delivered to the factory next year.

from the above inspection results and analysis, the following conclusions can be drawn:

(1) after the crane lifts the heavy object, the crane running mechanism will not slide in vain, causing the lifting weight translation injury:

(2) under on-site conditions, the wireless remote control device is unlikely to have non-human misoperation:

(3) the careless operation of the user, It should be the main cause of the accident, including the following points:

first, the driver is stopping_ 1. When the crane is operating, the emergency stop switch is not pressed or the power plug is unplugged:

secondly, when the driver is operating the crane, he does not notice that someone in the dangerous area of the crane is operating blindly:

thirdly, the party involved in the accident violates the relevant safety operation regulations and enters the dangerous area of the operation, resulting in an accident

5 preventive measures

(1) establish and continuously improve the safety management system for the use and operation of cranes. The use, operation and maintenance personnel of cranes shall carefully implement the requirements of relevant safety specifications, timely discover and eliminate unsafe factors existing in equipment, and ensure the safety of operating equipment

(2) strengthen the safety awareness, training and education of enterprise leaders, safety managers and operators. The cranes in use should be carefully inspected. If there are potential accidents, measures should be taken in time to rectify and eliminate them within a time limit: there should be no fluke thoughts and risky behaviors, and the policy of "safety first" should be implemented

6 conclusion

lifting machinery, as an indispensable equipment in modern industrial production, is widely used in the lifting, loading and unloading, installation, transportation and other operations of various materials. In the actual use process, there are multi-directional simultaneous operations, large activity space, complex and dangerous working environment in the lifting process, lifting objects are often in direct contact with lifting operators, and many people are often required to cooperate closely in the operation, This leads to frequent crane injury accidents. Therefore, the user unit must establish and effectively operate the safety production system, practically strengthen the training and education of operators and the safety management work on the operation site: operators must strictly implement the relevant safety operation procedures and operate according to the rules, so as to eliminate the hidden dangers of accidents and ensure the safe and reliable operation of lifting machinery

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