Prevention of the accident of the hottest screw ty

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Prevention of accidents of screw hoist top gate

screw hoist is widely used in culvert gates at all levels of channels in irrigation areas and gate opening and closing of water diversion projects because of its simple structure, simple installation, low price and other advantages. However, some screw hoists currently used do not have effective top gate accident protection measures. Even if the limit switch is installed on the manual electric hoist, it can only play a limit role. A little carelessness during the operation of the hoist will bend the screw, top the end cover of the hoist, top off the starting beam, crack and damage the upper edge of the reinforced concrete beam, and seriously, displacement, rotation and overturning of the hoist platform (beam) will occur, Even cause casualties. The electric hoist will also cause motor overload and burn the motor, which will seriously affect the safe operation of the project and threaten the personal safety of operators

1. Cause of top gate accident

1.1 top gate accident caused by human factors

the operator works carelessly, does not check first according to the gate opening and closing procedure, and then operate, or the original operator asks for leave for something, and the substitute operates blindly when he is not familiar with the opening and closing procedures and methods. If the opening and closing direction is reversed, the gate will be opened when the gate is in the closed state. Press the wrong button when opening and closing electrically or swing the opposite direction when opening and closing manually, and the wrong operation in the closing direction will be regarded as opening; Some operators are not concentrated when closing the gate, and the gate fails to shut down immediately when it reaches the lower limit position. Some limit nuts and limit marks of the screw are displaced, which does not play a limit role. The electric hoist will also encounter the change of power supply phase sequence when the power supply department is repairing electrical equipment or power supply lines, for example, the use of plastic materials in many car enterprises, resulting in the change of the original running direction of the motor on the hoist, resulting in the change of the hoisting direction of the hoist. At this time, if the gate is opened when the gate is closed, the jacking accident will occur. For example, this kind of top gate accident has occurred in the scouring gate of WeiJiabao channel in Baoji Gorge

1.2 top gate accident caused by non-human factors

during the operation of the gate, with the help of the first generation electric vehicle, it is fashionable and comfortable while saving energy. Floating objects such as trees or stones are brought to the bottom of the gate or washed into the gate slot and stuck by high-speed water flow. If this causes it to generate initial friction on the clamping surface, close the gate. When the lower edge of the gate has been blocked by obstacles before touching the bottom of the gate, reaction force will be generated, However, the limit mark or limit switch on the screw is not in place, so it cannot stop the machine or remind the operator to stop the machine. Therefore, the operator will not stop the machine, and the hoist will drive the gate to continue to press down. When the reaction force exceeds the endurance of the hoist or the hoist table, the gate jacking accident will also occur

2. Preventive measures for top gate accident

in addition to strengthening the working heart education and skill training of operators and requiring operators to operate according to the opening and closing procedures, the key is to improve technical measures to prevent the occurrence of top gate accident

to solve this problem, the following conditions must be met technically: first, it can send a misoperation alarm to the hoist personnel to remind the operator to stop the misoperation, and the electric hoist should be able to stop automatically to stop the misoperation accident; Second, it is required that the gate can automatically alarm when encountering obstacles to prevent the gate from descending in the process of descending, to remind the operator to stop the machine, and the electric hoist should be able to automatically stop the machine; Third, no matter what kind of automatic shutdown of the operation accident, it is possible to resume the operation again only after the operator removes the shutdown fault, so as to avoid the accident caused by repeated operation when the fault is not eliminated

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