Anti falling safety device, safety switch
The anti falling safety device is an important part of the construction elevator. It is necessary to rely on it to eliminate the cage falling accident and ensure the life safety of the passengers. Therefore, the factory test of the anti falling safety device is very strict. Before leaving the factory, the legal inspection unit measures its torque, critical speed, and spring compression. Each device is attached with a test report, assembled to the construction lift After landing on the machine, carry out the falling test under the rated load, while the elevators in use on the construction site must carry out the falling test every three months. The two-year anti falling safety device (the date of delivery on the anti falling safety device) must also be sent to the legal inspection unit for testing, and then tested once a year. So far, few people have been sent for inspection. Some construction sites don't even do the fall test once every three months. They think their fall safety device is OK, but once there is an accident, they regret it. Why not test and send for inspection regularly according to the system? The user blindly thinks it's good if it's not bad. In fact, the quality of anti falling safety device can only be judged by test and inspection. It is impossible to determine whether it is good or not in daily operation. For those over service anti falling safety devices, it is suggested that they should be submitted for inspection and regular test earlier. Only by knowing well, can malignant accidents be prevented in advance.
The safety switches of the elevator are designed according to the safety requirements, including fence threshold, cage threshold, top door limit, limit switch, upper and lower limit switch, counterweight anti breaking rope protection switch, etc. In order to save trouble, some limit switches are canceled artificially and are short circuited or not repaired in time after being damaged on some construction sites, which is equivalent to canceling these safety lines and planting accident hidden dangers. For example: the cage shall be loaded with long things. If the cage cannot be put down, it needs to extend out of the cage. However, the threshold or top door limit shall be cancelled artificially. In the case of the above safety facilities are not perfect or intact, the cage shall be loaded as usual In order to avoid the occurrence of potential accidents, it is hoped that the leaders of the using unit will strengthen management, strictly require the elevator maintenance and operators to regularly check the safety and reliability of various safety switches, and put an end to accidents.
Wear replacement of gear and rack
During the construction on the construction site, the working environment is poor, cement, mortar and dust can not be eliminated. The gears and racks are grinded mutually, 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 and replace the new ones? It can be measured with a 25-50 mm normal micrometer. When the length of the common normal of the gear is worn from 37.1 mm to less than 35.1 mm (2 teeth), the gear must be replaced. When the rack is worn, 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, the rack must be replaced. However, many "old" gear and rack elevators on the construction site are still in overdue service. In order to be safe, new accessories must be replaced.
Definition of temporary load rate
The elevator on the construction site operates frequently and has a high utilization rate, but the problem of 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). Its definition is FC = working cycle time / load time × 100%, in which the working cycle time is the load time and shutdown time. On some construction sites, the elevator is rented by the leasing company, which always wants to make full use of it. However, the temporary load rate of the motor (FC = 40% or 25%) is totally ignored. How can the motor not generate heat? Some of them are still in use even when they smell burnt, which is a very abnormal operation. If the transmission system is not well lubricated or the running resistance is too large, it is overloaded for use, or it is frequently started, then it is even more a small horse pulling the cart. Therefore, every driver on the site must understand the concept of temporary load rate and act according to scientific rules. The motor itself is designed according to intermittent operation.
Buffer safety door
The last line of defense for the safety of the construction lift of the buffer on the construction lift, first, it must be set, second, it must have certain strength, be able to bear the impact of the rated load of the lift, and play the role of buffer. Many construction sites, some of which have settings, but they are not enough to play the role of buffer. There is no buffer at all on the site, which is extremely wrong. It is hoped that the user should pay attention to the inspection and do not despise the last line of defense.
Safety doors shall be set at each stop floor of the construction elevator. It is obvious that if not set up according to the requirements, the construction personnel waiting at a high place are prone to fall accidents. When setting the stop safety protection door, the height of the safety protection door shall be no less than 1.8m, and the landing door shall be equipped with interlock device. If the cage is not in the stop position, the protection door cannot be opened, so as to ensure the safety of the operators. 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.
Foundation fence wire rope
According to gb10055, "the foundation fence shall be equipped with mechanical interlocking or electrical interlocking. The mechanism interlocking shall make the cage only be 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 number of construction elevators. When the cage is close to the fence door, the bottom of the cage presses a crossbeam to run downward. The steel wire rope of the reversing pulley drives the fence door to open upward. This is not allowed, and it is easy to cause harm to people near the fence.
Reliable connection mode shall be adopted for wire rope ends of all parts, such as casting, weaving, forging and wedge-shaped fastener. 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 wire rope. The number of rope clamps matching the rope diameter is - 36. The minimum number of rope clamps is 3456.
The spacing between clamps shall not be less than 6 times of the diameter of the steel wire rope, the length between the rope head and the last clamp shall not be less than 140mm, and shall be tied with fine steel wire. The pulley of the clamp shall be placed on the stressed side of the steel wire rope when it is working, the U-bolt shall be fastened on the tail end of the steel wire rope, and the clamp shall not be set in a crisscross way. Before the steel wire rope is stressed, the clamp shall be fixed, and it shall be tightened again after being stressed. However, due to the lack of safety awareness in many construction sites, when using rope clamps for fixation, the number, spacing, setting between ropes, length of tail end, etc. of rope clamps do not follow the standard, resulting in the discount of the joints with the original fixation strength of only 80% - 85%, leaving a potential safety hazard.
Cage top control box
According to 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 using the control box at the top of the cage, other operating devices do not work. At this time, the safety device of the cage still plays a protective role. The constant pressure button or bistable switch shall be used for the operation of the cage top control. The non self reset emergency stop switch shall be installed on the cage top. The circuit can be cut off at any time to stop the cage action ". This article is mainly for SC construction elevator. Few enterprises' products can meet the five provisions of this article at the same time: including some products designed by famous design units. What's the harm of not meeting these five regulations? It may cause safety accidents due to the misoperation of installation and maintenance personnel. It is hoped that the relevant users will check the construction elevator, especially the old products. If they do not meet the above requirements, they should actively take measures to transform them.
Fault phase protection
Overvoltage, undervoltage and fault phase protection device is used to protect the device and stop the construction elevator when voltage drop, overvoltage and fault phase and fault phase of electrical circuit occur. Some construction elevator maintenance personnel on the construction site do not timely eliminate the fault that causes the action of over undervoltage and wrong phase protection device, but cancel or short-circuit the protection device to make it ineffective and leave accident potential for the equipment. Some early products do not have the protection device at all, so it is recommended to equip them. The construction elevator shall be able to carry people and goods under the reliable and effective condition of over and under voltage and phase fault protection device.