Problems needing attention in daily use safety and

2022-10-22
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Discussion on the problems that should be paid attention to in the daily use safety and inspection of construction elevators

I. construction elevators

1. There are 18 inspection standards in the new regulations for elevators, of which 6.6.14; 6.6.15 there are 2 mandatory provisions, covering 12 safety protection devices of the whole machine

2. Mandatory provisions for lifts

(1) 6.6.14 safety protection devices for construction lifts must be safe, reliable and effective

(2) 6.6.15 the air defense safety device of the construction lift must be sensitive, effective, reliable and within the validity period of verification

II. On site inspection

1. Foundation parts: first check whether there is water accumulated at the beginning of this month and whether there is any sign of subsidence. If an elevator (basement roof) installed on the first floor is found during the inspection, the jacking system and calculation scheme of the basement must be checked; Check whether the grounding system meets the requirements; The buffer (spring) shall be complete and effective; The enclosure of the bottom cage is tight without damage; The entrance and exit of the bottom floor of the lift shall be equipped with double-layer protective sheds

2. Frame structure: check the fastening of the connecting bolts of the foundation and the standard section, and set double nuts and single nuts of the standard section and spring pads for the foundation bolts as required; The welds of all parts are intact without cracks; The attached rods shall be set according to the materials and specifications required by the instructions, and shall not be changed arbitrarily. The distance between the attachment rods shall meet the requirements of the instructions, generally 6m (no more than 9m); The connection method and fastening method of the attachment rod should be implemented according to the requirements of the manual, and should not be changed at will. In the process of safety inspection, it is found that steel bars are used to replace bolts, and steel heads are welded at both ends of the steel bars to replace nuts. The supports are connected with steel pipe fasteners, or the supports are pulled and locked on the concrete slab with expansion screws. This practice is very dangerous

3. Mechanical transmission system: the mechanical transmission of the elevator can be divided into closed and open parts. Its speed change part (worm gear, worm reducer) and the centrifugal braking part of cone drum speed limiting air are closed. Other parts are open. The closed part is not easy to check. On site, we can only check whether the gearbox leaks oil and whether the detection date marked on the nameplate of the cone and drum speed governor is overdue. Its detection cycle is generally one year. The cone and drum speed governor (progressive speed governor) must be regularly monitored by the national safety testing center and sealed with lead. It can be used by clicking on the Merlin unit at the bottom. It is not allowed to adjust at will. The inspection and detection of the opening part are different. Because the safety inspection involves many points and a wide range, and the time is limited, the safety inspection of the elevator is more extensive than that of the elevator

generally, without instruments, it is all based on experience. First, check that the clearance of each transmission part cannot be too large, which is generally controlled at about 0.2~0.5mm. The clearance at the bottom of the gear when the gear is matched with the rack is 2.0mm. Excessive meshing clearance or serious wear of the gear and rack are very dangerous. The operation and braking force of the elevator must be transmitted through the gear and rack. Insufficient meshing depth, serious wear or excessive axial dislocation will reduce the meshing area, reduce the strength of the gear and rack, and cause tooth breakage accidents. During the actual safety inspection, it was found that the gear rack of the elevator only hung on the tooth tip, and the meshing surface could not reach even 1/3, or the old and new racks were uneven, with abnormal noise or vibration, which was very dangerous. The adjustment of meshing clearance mainly depends on the correct positioning of the rack guide wheel and guide rail

during the inspection, it should be noted that the gap between the guide wheel and the rack should not be too large, generally 0.2~0.5mm, and the gap between the roller and the guide rail should also be controlled within 0.2~0.5mm. The elevator should run smoothly without abnormal noise and obvious vibration. If there are three reasons for shaking, shaking and shaking, according to different reasons, first, check whether the frame and the wall attachment device are loose and not fastened; Second, check whether the guide wheel and side wheel are damaged, loose or meshed with clearance; The third is to find out whether the gears, back wheels and racks mesh or whether the gears and racks have been worn into a sharp shape

4. Safety device of elevator

there are many safety devices for elevators, mainly including the following more than ten kinds:

(1) the door chain of the bottom cage, including mechanical and electric. When the lifting cage rises, the mechanically interlocked bottom cage door will automatically fall and close. When the bottom cage door of the electrical appliance interlock is open, the other doors of the cage are closed, and the elevator should not be able to start, otherwise it is regarded as the bottom cage door interlock failure

(2) the feeding door chain of the hanging cage also has two types: mechanical and electrical. The mechanical chain door cannot be opened during the lifting process of the cage. If it can be opened, it shows that the chain is out of order; When the electrical interlock door is opened during the lifting process, the cage will stop automatically. If it cannot stop automatically, it indicates that the interlock fails

(3) the middle door of the outlet is opened, and the inspection method is the same as that of the inlet

(4) the floor safety door should be able to be reliably locked and can only be opened when the cage is parked. The height should exceed the average height of ordinary people (1.80m) to prevent the head from sticking out of the door. First, the strength of the platform door on this floor should meet; Second, the height should be consistent; Third, do normally closed; Fourth, the protection should be strict

(5) check the limit switch, not only whether the switch is effective, but mainly whether the collision process between the switch and the upper and lower limit bumpers is accurate, sensitive and reliable. After the limit switch acts, it cannot be reset automatically, because it cuts off the main power supply, so that the lifting cage cannot be started up and down, and can only be restored manually

(6) the upper and lower limit switches are two switches that control the rising circuit and the falling circuit respectively. Check whether their collision process is accurate, sensitive and reliable. For the inspection of limit switches and upper and lower limit switches, manual methods cannot be used to replace the test of collision process. Because in the previous inspection, it was found that there were instances of whether the collision block was installed or misaligned

(7) there are many forms of installation of anti breaking (loosening) rope limit: A. some rely on the eccentric rope sheave to touch. In case of rope breaking (loosening) accident, the rope sheave falls down to the direction of gravity center, press the limit switch to cut off the power supply and stop the operation of the bridge box. b. If it is touched by the hinged rope sheave, the hinged rope sheave shall be equipped with a reverse control spring to ensure that the rope sheave dumps in the direction of the limit switch in the case of rope breaking (loosening) accident

(8) limit of the top door. There is a movable door on the top of the bridge box for the press and disassembly personnel to get up and down. In order to ensure safety during the elevator lifting, the movable door on the top must be closed. Therefore, the movable door is equipped with a limit switch to ensure that the top door operates in the closed state. During the safety inspection, you can test the quality of the limit switch by pushing the door with a wooden stick

(9) the installation spacing of the cable protection frame should not be greater than 6m. When the spacing is too large, the cable will be bent by the wind and hung on the scaffold in windy weather, so that the bridge box cannot be lowered. In serious cases, the cable will be hung up, causing accidents. Such examples have been found during the safety inspection

(10) the emergency stop switch is installed on the control panel operated by the driver for use in case of emergency (in case of other limit positions and switch failure). Press the emergency stop switch once, and the bridge box in the lifting process should stop immediately

(11) the sound of the alarm bell should be clear, and the alarm bell should be sounded before the elevator starts and stops

(12) the protective shed at the ground feed inlet of the elevator must be set up according to the safety technical requirements for high-altitude operation to meet the anti smashing protection requirements

5. Electrical system:

(1) switch box and leakage protector should be set

(2) wires and cables should be well insulated without damage and leakage. The metal hose passing through shall be free of rust and damage, and shall be reliably connected to neutral

(3) according to gb005-88, the grounding resistance of the elevator should not exceed 4 Ω

(4) instruments, lighting and control devices should be intact and sensitive

6. Steel wire rope and pulley system:

(1) the specification of steel wire rope shall be configured according to the specification requirements of the manual, without strand breakage and diameter reduction, and the number of broken wires shall not exceed the scrap standard

(2) the pulley operates flexibly, and it should be replaced in time. It should be smooth and stable

(3) when the steel wire rope is fixed, there should be no less than four rope clamps at each end (both sides of the rope clamp are provided with anti damage rope measures)

III. safety data

1. Whether the installation and removal plan can guide the safe construction and have complete approval procedures

2. The installation and demolition team must hold the safety qualification certificate issued by the competent department at or above the provincial level

3. The safety technical disclosure for installation and removal personnel and elevator drivers should have targeted content

4. There should be foundation design, concealed acceptance and concrete strength report

5 acceptance records after installation, test reports of the testing department and filing and registration of the competent department

6. Jacking record

7. The original or copy of the elevator instruction manual

8. Special operation post certificate of installation and disassembly personnel

9. Other relevant safety data

IV. conclusion

the construction elevator is a large vertical transportation equipment, and the past accident cases and blood lessons are very profound. Through strict inspection, preventing elevator safety accidents is a very important link in the safety management of the construction site. Safety managers at all levels should always keep a clear understanding of this

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