Nine problems that need to be paid attention to in the safe use of screw lifts

Standardized management can allow an enterprise to develop steadily and benignly, and it is also a manifestation of being responsible for the lives of employees and site personnel.Transmission machinery such as: gear reducer,Worm gear reducer, hard tooth surface reducer, etc., each type of transmission equipment must comply with certain usage specifications when in use.The screw lift is an indispensable mechanical equipment for the vertical transportation of various construction projects.Over the years, vicious accidents in the construction of screw elevators have occurred from time to time. The reason is that the management measures are not in place, and the lack of scientific teaching methods is the root cause of the hidden dangers of construction accidents.Taking SC type screw elevator as an example, several problems that cannot be ignored are put forward.

XNUMX. Regularly test and submit the anti-fall safety device for inspection
  The anti-fall safety device is an important part of the construction elevator. It is necessary to rely on it to eliminate the occurrence of cage falling accidents and ensure the safety of the occupants.Therefore, the factory test of the anti-fall safety device is very strict. Before leaving the factory, the legal inspection unit will measure the torque, the measurement at the critical speed, and the measurement of the spring compression. Each set is attached with a test report and assembled on the construction lift. After that, a drop test under the rated load is carried out, and the lifts in use on the construction site must be subjected to a drop test every three months.For the anti-fall safety device that has been out of the factory for two years (the date of manufacture on the anti-fall safety device), it must also be sent to the legal inspection unit for testing and testing, and then it will be tested once a year.So far, few people have sent them for inspection. Some construction sites don't even do a drop test every three months. They all think that their anti-fall safety device is fine, but once an accident occurs, they will regret it.Why not regularly test and submit inspections according to the system?The use unit blindly thinks it's good if it's not bad.In fact, the quality of the anti-fall safety device can only be judged by testing and submitting it for inspection. It is impossible to determine whether it is good or bad in daily operation. For those anti-fall safety devices that have been in service over a period of time, it is recommended to submit them for inspection early and regularly. Experiments are good, and only by knowing what to do can we prevent vicious accidents before they happen. (The detection of the anti-fall safety device 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 and reliability of various safety switches
  The safety switches of screw lifts are designed according to safety requirements, including fence door limit, hanging cage door limit, top door limit, limit switch, upper and lower limit switch, counterweight anti-rope breaking protection switch, etc.In some construction sites, in order to save trouble, some limit switches are artificially canceled and short-circuited or not repaired in time after damage, which is equivalent to canceling these safety lines of defense and planting hidden dangers of accidents.Example: The hanging cage needs to be loaded with long things, and the hanging cage needs to extend out of the hanging cage if it cannot fit inside the hanging cage, and the door limit or the top door limit is manually canceled. If the above safety facilities are not perfect or in good condition, people and objects can still be carried. , This kind of illegal operation is a joke on human life. In order to avoid the occurrence of hidden dangers of accidents, it is hoped that the leaders of the user units will strengthen management, and strictly require elevator maintenance and operators to regularly check the safety and reliability of various safety switches to prevent accidents.
3. Wear and replacement of the gear and rack of the screw elevator
  Construction on the construction site, the working environment is harsh, cement, mortar, and dust cannot be eliminated. 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 profile should be like a cantilever beam, and when it wears to a certain size, the gear (or rack) must be replaced.To what extent should you stop using it and replace it with a new one?It can be measured with a 25-50mm common normal micrometer. When the common normal length of the gear is worn from 37.1mm to less than 35.1mm (2 teeth), a new gear must be replaced.When the rack is worn, it is measured by the tooth thickness caliper. When the chord height is 8mm, the tooth thickness is worn from 12.56mm to less than 10.6mm. It is still in overdue service and must be replaced with new parts for safety reasons.
4. Understand the concept of motor duty cycle and act according to scientific laws
  The elevators on the construction site operate frequently and the utilization rate is high, but the intermittent working system of the motor has to be considered, that is, the problem of the temporary load rate (sometimes called the load duration rate), which is defined as FC = working cycle time / load Time × 100%, where duty cycle time is load time and downtime.On some construction sites, the lifts are rented by leasing companies, and they always want to make full use of them. However, the temporary load rate of the motor (FC=40% or 25%) is completely ignored. Why does the motor not heat up?Some are still in use with a burnt smell, which is very abnormal.If the transmission system is poorly lubricated or the running resistance is too large, overloaded, or frequently started, it is even more of a small horse-drawn cart.Therefore, every driver on the construction site must understand the concept of duty cycle and act according to scientific laws. The motor itself is designed for intermittent operation.
5. Set up a screw lift buffer with a certain strength
  The buffer on the construction screw 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 buffering role.Now many construction sites, although some have settings, are not enough to play the role of buffering, and there are no buffers at all on some construction sites, which is extremely wrong. I hope that the user will pay attention to inspection and do not despise this last line of defense.
6. Set the floor parking safety door
  Each parking layer of the construction screw elevator should be equipped with a parking safety door.Obviously, if it is not set up as required, construction workers waiting at high places are prone to accidental falls.When setting the parking safety protection door, the height of the safety protection door should be ensured not less than 1.8m, and the landing door should be equipped with an interlocking device. When the hanging cage has not reached the parking position, the protective door cannot be opened to ensure the safety of the operators.At present, there are generally people waiting for the construction elevator on the construction site to open the safety door at any time, which is very dangerous and should be paid attention to.
7. Equipped with mechanical interlocking or electrical interlocking basic fence
  According to the provisions of GB10055, "the foundation fence should be equipped with mechanical interlocking or electrical interlocking, and the mechanism interlocking should be such that the foundation fence door can only be opened when the cage can only be located at the position specified at the bottom, and the electrical interlocking shall enable the protective fence to be opened after The cage stops and cannot be started".There are quite a few construction lifts. When the cage is close to the fence door, the bottom of the cage presses a beam to run down, and the fence door is opened upward through the reversing pulley wire rope. cause harm to people.
8. Wire rope with reliable connection
  The wire rope ends of each part should be connected in a reliable way, such as casting weaving, forging and wedge-shaped solid parts. If using U-shaped rope clips, there should be no less than 3 rope clips. The number of rope clips and the distance between the rope clips are related to the diameter of the wire rope.The distance between the rope clamps is not less than 6 times the diameter of the wire rope, the length of the rope head from the last rope clamp is not less than 140mm, and must be bundled with thin steel wires. At the end of the wire rope, the rope clips should not be set in a staggered manner. The rope clips should be fixed before the wire rope is subjected to force, and then tightened after the force is applied.However, due to the lack of safety awareness in many construction sites, when rope clips are used for fixing, the number of rope clips, the distance between the ropes, the setting between the ropes, the length of the tail end, etc. are arbitrary, not according to the standard, resulting in only 80%-85% of the fixed strength of the joints are discounted. leave a safety hazard.
9. There is a control box on the top of the cage used for maintenance or disassembly
  It is stipulated in GB10055 that "the top of the cage should be provided with a control box for maintenance or disassembly, and it is allowed to run at a speed not higher than 0.65m/s under various speeds. When using the control box on the top of the cage At this time, the safety device of the cage still plays a protective role. The top control of the cage should be operated by a constant pressure button or a bistable switch, and a non-self-reset emergency stop should be installed on the top of the cage The switch can cut off the circuit at any time and stop the action of the cage.”This article is mainly aimed at SC-type construction lifts. Few companies' products can meet the five requirements of this article at the same time: including products designed by some well-known design units.What's the harm in not meeting these five requirements?Safety accidents may be caused due to the misoperation of installation and maintenance personnel.It is hoped that the relevant user units will conduct a comparative inspection of the construction hoist, especially the old products. If they do not meet the above regulations, they should actively take measures to transform them.