Precautions for safety maintenance of the hottest

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Precautions for safety maintenance of bridge crane

bridge crane is a kind of hoisting and transportation machinery commonly used in factories, accounting for about 80% of the total number of all cranes. Therefore, its safety management and use are very important. The statistical results of relevant accidents show that the bridge crane causes the largest proportion of accidents. For example, according to the statistics of 42 lifting deaths and serious injuries, the accidents caused by bridge cranes account for 90% of all accidents. There are ll bridge cranes in our factory, with a rated load of 5 ~ 15 tons. In recent years, in the process of daily use and management, some unsafe factors affecting the performance of the equipment have been found. If they are not handled in time, they may cause faults, affect the normal progress of production, or even accidents. The following analyzes various unsafe factors that may exist in the bridge crane, so as to put forward effective treatment methods according to the actual problems of the equipment

I. composition of bridge crane

bridge crane is a device that uses hooks (also used grab or electromagnetic disk) to lift heavy objects. Its appearance is in the shape of a bridge, and both ends of the bridge are on the track through roller frames. The roller moves along the track to drive the movement of the bridge. Structurally, the bridge crane is mainly composed of three parts, namely, metal structure, mechanical transmission and electrical equipment

(1) the metal structure is mainly composed of bridge, walkway, cab, etc. It mainly bears heavy loads, places mechanical and electrical equipment, and forms the whole bridge crane

(2) the mechanical transmission part mainly includes the crane part and the trolley part. The crane part includes the crane running mechanism, etc., and the trolley part includes the trolley frame running mechanism, lifting mechanism, etc

(3) electrical equipment mainly includes protection panel (distribution panel), controller, collector (power supply sliding line), motor lighting, various limiters, interlocking switches, grounding and other safety protection devices

II. Safety protection of "bridge crane"

the bridge operating mechanism and trolley frame elevator bracket of bridge crane are not convenient for regular inspection. According to the relevant regulations, they must be managed according to the type of special equipment. First, according to the relevant regulations and in combination with the actual situation of the factory, the bridge cranes of all units in the factory are required to be installed with overload limiter, lifting limit position limiter, rail sweeping plate and support frame At the same time, the technical requirements of protective devices have been formulated. For example:

(1) when the lifting load reaches 90% of the rated load, the system sends an alarm signal; When the lifting load reaches the rated load, the system can automatically cut off the power supply and send an alarm signal

(2) when the lifting appliance rises to the limit position, it should be able to automatically cut off the lifting power supply

(3) protective plates shall be set under the end beam at the sliding line end of the crane to prevent accidental contact between the lifting appliance or steel wire rope and the sliding line: protective plates shall be set between the access ladder and the walking platform and the sliding line

(4) set a stop at the end of the track to prevent the derailment of the bridge

III. safety precautions for metal structure of "bridge crane"

during the use of PVG bridge crane, it must be ensured that the bridge girder does not produce excessive downward deflection and permanent downward deflection deformation. Otherwise, there will be the following hazards:

(1) make the car slip after braking, and cannot stop accurately. When the car climbs, it will cause motor overload and burn out the motor

(2) the transmission shaft of the traveling mechanism is twisted and stressed too much. The coupling connecting bolt is twisted and broken, and even the shaft is broken

(3) deformation of trolley rail, resulting in wheel slide, and even trolley derailment accident; The cracks on the lower cover plate and web of the main beam seriously threaten the safe operation

IV. safety precautions for the mechanical part of the bridge crane

the parts of the bridge crane must be inspected regularly, Avoid accidents

(1) uneven wear of pulley groove is easy to cause even contact of steel wire rope pulley, and serious cases will lead to operation accidents; excessive wear of pulley shaft is easy to cause fracture of pulley shaft. Once the wear exceeds the relevant regulations, it must be replaced.

(2) if the wear of drum exceeds the standard or fatigue cracks appear, it is easy to cause drum damage; If the winding key is seriously worn, it is easy to cause the key to fall off and cut off, and in serious cases, it is easy to cause heavy objects to fall. In this case, it should be replaced

(3) the small shaft, spindle, brake wheel, brake shoe material pad of the brake are worn beyond the standard, and the fatigue cracks of the pull rod and spring are easy to cause brake failure, so it should be replaced

(4) if the dangerous section at the opening of the hook is worn beyond the standard, or the tail and tail thread are undercut, and fatigue cracks appear on the surface of the hook, it is easy to cause the fracture of the hook. Therefore, the hook should be checked 1 ~ 3 times a year, and the problem should be replaced in time if it is found

(5) if the spokes and tread of the crane wheel have fatigue cracks, or the wheel flange and tread wear exceed the standard, it is easy to cause wheel damage, and in serious cases, it will cause the crane derailment

(6) if there is oil on the track, the motor starts too hard, and the wheel pressure is uneven, it is easy to cause the trolley running mechanism to slip; Trolley deviation, unequal wheel diameter, excessive wheel installation error, deformation during the manufacturing process of the car body, wheel pressure can not be obtained. The tensile strength, yield strength, specified non proportional extension strength, elastic modulus and other performance indicators of the measured materials are easy to get up, and the trolley wheel is stressed evenly, which must be adjusted

(7) regularly check the temperature, sound and lubrication of each bearing of the crane; If the reducer has abnormal sound, it should be repaired or replaced in time

(8) if the deviation of the transmission system is too large, the frame deflects and deforms, the installation error of the track and wheels is too large, and oil is stored on the track, it is easy to cause the dog car to run gnawing, so it must be adjusted, cleaned and corrected in time

v. safety precautions for electrical equipment of bridge crane

the driving motor of bridge crane realizes the front and rear, left and right, up and down movement of the hook through deceleration and transmission mechanism. In order to ensure work safety, necessary electrical protection systems should be set, such as main isolation switch, emergency power-off switch, short circuit protection, overload protection, limit protection, etc. Regularly check the sound and heat of the motor and whether the electromagnet works normally. Whether the controller and contactor are flexible and easy to use. It must be done: first, to prevent the loss of control caused by operation errors or electrical failures such as controllers and protection panels, and heavy objects from falling or hitting; Second, prevent electric shock accidents caused by touching exposed power supply sliding wires, insulation damage and poor grounding; III 2 The main motor source of the pipe ring stiffness testing machine has power, but the equipment cannot move up and down. It is in flammable and explosive places, so the explosion-proof electric crane must be used

6 inspection and test of bridge overweight machine

(1) generally, the bridge crane should be inspected once a year

(2) all overhead cranes that have been newly installed, overhauled, transformed and normally used for two years or have been out of service for more than one year shall be tested in accordance with the lifting machinery test procedures and can be put into use only after passing the test

(3) load test includes no-load test, static load test and dynamic load test

VII. Matters needing attention in inspection and test work

(1) special personnel must be appointed to be responsible for inspection and test work. Before the work starts, safety education must be carried out for relevant personnel to make them understand the requirements of relevant procedures, and the division of labor should be clear

(2) carry out the final inspection of the bridge crane according to the safety regulations for mechanical, electrical and high-altitude operation

(3) when the car is too small, the commander must send a signal after confirming the safety.

(4) except that anyone can send a stop signal in an emergency and dangerous situation, only the commander is allowed to send a command signal

(5) during the test, what is the development prospect of graphene, the "king of new materials", in China? Stand in a safe position

(6) safety measures should be formulated for emergency in case of emergency and danger

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