What should be paid attention to in the safe use o

2022-07-24
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What should be paid attention to in the safe use of lifts

problems needing attention in the safe use of lifts:

lifts are indispensable construction equipment for vertical transportation of construction projects. In recent years, malignant accidents of construction elevators have occurred from time to time. The root cause is that the management measures are not in place and lack of scientificity, which is the root cause of hidden dangers of construction elevators. Taking SC type construction elevator as an example, this paper puts forward several problems that need to be paid attention to

1. Regular test and inspection of anti falling safety device

anti falling safety device is an important part of the construction elevator. It should be relied on to eliminate the occurrence of cage falling accidents and ensure the life safety of passengers. Therefore, the delivery test of the anti falling safety device is very strict. Before delivery, the legal inspection unit shall measure its torque, critical speed and spring compression. Each device is attached with a test report. After it is assembled on the construction elevator, the drop test under rated load shall be carried out. However, the elevator in use on the construction site must undergo a drop test every three months. For the anti falling safety device that has been delivered for two years (the date of delivery on the anti falling safety device), it must also be sent to the legal inspection unit for testing, and then tested once a year. So far, few people have submitted for inspection. Some construction sites have even failed to conduct a fall test every three months. They all think that their fall safety devices are OK, but they will regret once there is an accident. Why not regularly test and submit for inspection according to the system? The user blindly thinks that it is good if it is not bad. In fact, the quality of fall arrest safety devices can only be judged by testing and inspection. It is impossible to determine whether they are good or bad in daily operation. For those fall arrest safety devices that have exceeded their service life, it is recommended that they should be submitted for inspection early and tested regularly. Only when they are well aware can they prevent malignant accidents. (the detection of anti falling safety devices can be sent to Changsha National Construction Machinery Quality Inspection Center, Shanghai Academy of construction Sciences, Shanghai Jiaotong University, etc.)

2. Regularly check the safety reliability of various safety switches

the safety switches of elevators are designed according to safety needs, including fence threshold, cage threshold, top door limit, limit switch, upper and lower limit switches, counterweight anti breaking rope protection switch, etc. In some construction sites, some limit switches are artificially cancelled, short circuited or damaged, and they are not repaired in time, which is equal to 4 The thermocouple scanning device cancels these lines of safety defense, planting potential accidents. For example, the cage should be loaded with long objects, which cannot be placed in the cage and need to extend out of the cage. However, the door limit or top door limit is cancelled artificially. When the above safety facilities are imperfect or incomplete, people and objects can still be loaded. This illegal operation is a joke on people's lives. In order to avoid the occurrence of potential accidents, it is hoped that the leaders of the user units will strengthen management, Strictly require the elevator maintenance and operation personnel to regularly check the safety and reliability of various safety switches to prevent accidents

3. Wear and replacement of gears and racks

construction on the construction site, the working environment conditions are poor, the cement, mortar and dust cannot be removed, and the gears and racks grind each other, and the teeth are sharpened and still in use, which should be paid attention to. As we all know, the tooth shape should be like a cantilever beam. When it is worn to a certain size, the gear (or rack) must be replaced. To what extent should we stop using it and replace it with a new one? The mm Common Normal micrometer can be used for measurement. When the common normal length of the gear is worn from 37.1mm to the result that it is found that this kind of mixture adheres to the combustor longer than the ordinary flame retardant and is less than 35.1mm (2 teeth), the gear must be replaced. After the rack is worn, it is measured by the tooth thickness caliper. When the tooth thickness is worn from 12.56mm to less than 10.6mm when the chord height is 8mm, the rack must be replaced. However, many "old" gear and rack elevators on the construction site are still in extended service. In order to be safe, new accessories must be replaced

4. Understand the concept of motor temporary load rate and act according to scientific laws

elevators on the construction site operate frequently and have high utilization rate, but we have to consider the problem of intermittent working system of the motor, that is, the introduction to the commonly used temporary load software: the problem of rate (sometimes called load duration rate) is defined as fc= work cycle time/load time × 100%, where the duty cycle time is the load time and downtime. Some elevators on construction sites are rented by leasing companies, who always want to make full use of them. However, the temporary load rate of the motor (fc=40% or 25%) is completely ignored. Why doesn't the motor heat up? How can a successful bidder make profits? It is abnormal to use the product even with a burnt smell. If the transmission system has poor lubrication or excessive running resistance, is overloaded, or is started frequently, it is even more like a small horse pulling a cart. Therefore, every driver on the construction site must understand the concept of temporary load rate and act according to the scientific law. This motor is designed for intermittent operation

5. Buffer with certain strength

the buffer on the construction elevator is the last line of defense for the safety of the construction elevator. First, it must be able to withstand the impact of the rated load of the elevator and play a buffer role. However, at present, many construction sites have been set up, but they are not enough to play a buffer role. There is no buffer at all on the construction site with land, which is extremely wrong. I hope the user unit will pay attention to the inspection and do not underestimate this last line of defense

6. Set safety protection door for floor parking

safety protection door for parking shall be set at each parking floor of construction elevator. Obviously, if it is not set according to the requirements, the construction personnel waiting at heights are prone to accidental falling accidents. When setting the safety protection door for parking, it shall be ensured that the height of the safety protection door is not less than 1.8m, and the landing door shall be equipped with an interlock device. The protection door cannot be opened before the cage reaches the parking position, so as to ensure the safety of operators. At present, it is very dangerous for people waiting for the construction elevator to open the safety door at any time, which should be paid attention to

7. Foundation fence equipped with mechanical or electrical interlocking

according to the provisions of gb10055, "the foundation fence shall be equipped with mechanical or electrical interlocking. The mechanism interlocking shall make the cage only be located at the position specified at the bottom, and the foundation fence door can be opened. The electrical interlocking shall make the cage stop and cannot be started after the protective fence is opened". There are quite a few construction elevators. When the cage is close to the fence door, the bottom of the cage presses a beam down and drives the fence door to open upward through the reversing pulley wire rope. This is not allowed, and it is easy to cause harm to people near the outside of the fence

8. Steel wire rope with reliable connection

the steel wire rope ends at all parts shall be reliably connected, such as casting, weaving, forging and wedge-shaped fasteners. If U-shaped rope clamps are used, there shall be no less than 3. The number and spacing of rope clamps are related to the diameter of steel wire rope. See table 1

the number of rope clamps matching the rope diameter

the diameter of steel wire rope 9 The control box at the top of the lifting cage used for maintenance or disassembly is set according to the provisions of gb10055 "The top of the cage shall be equipped with a control box for maintenance or disassembly, and it is only allowed to operate at a speed not higher than 0.65m/s under various speeds. When the top control box of the cage is used, other operating devices will not work. At this time, the safety device of the cage still plays a protective role. The top control of the cage shall be operated by a constant pressure button or a bistable switch, and a non self resetting emergency stop switch shall be installed on the top of the cage, The circuit can be cut off at any time to stop the action of the cage ". This article is mainly aimed at SC type construction elevators. Few enterprises' products can meet the five provisions of this article at the same time: including products designed by some famous design units. What are the disadvantages of not meeting these five provisions? It may cause safety accidents due to misoperation of installation and maintenance personnel. It is hoped that the relevant user units will carry out comparative inspection on the construction elevators, especially the old products. If they do not meet the above requirements, they should actively take measures to transform them

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