Technical requirements for pre installation of cantilever crane rails
1. The strength grade of cantilever hanging concrete leveling layer is C30, and the thickness is 30 to 50mm.
2. Before the construction of the concrete leveling layer, the installation deviation of the track beam should be checked according to the requirements, and if it does not meet the requirements, the track beam should be adjusted.
3. According to the measured elevation of the track beam surface, a suitable control elevation of the top of the concrete leveling layer is determined, and a reference point of the control elevation is set every 214-310m on the track beam.
4. Measuring with the instrument, the cantilever crane adjusts the elevation of the datum point, determines the datum line of the top elevation of the leveling layer, then installs the formwork, clears the debris in the top surface of the track beam and the bolt hole, blocks the upper opening of the bolt hole, sprinkles the water and wets the concrete.
5. The top of the leveling layer must be leveled and calendered, and there must be no exposed or uneven stones. The method of placing cement mortar on the surface is not allowed to leveling.
6. In cantilever crane construction, the top surface of leveling layer must satisfy the following requirements: the unevenness of the top surface within the width of 400 mm at the bolt is less than 5 mm; the difference of the top surface elevation at the internal affairs bolt of any 610 m length is (+) 3 mm; and the difference of the top surface elevation along the bolt is (+) 5 mm.
7. The cantilever concrete should be mechanically stirred, and the maintenance should be strengthened during construction. The track installation can only be carried out when the concrete specimen reaches 75% strength design value.
Eight points for attention in the operation of overhead boom cranes
Matters needing attention in the operation of jib crane:
1. Check whether the worksite is smooth and solid before use. If the lower legs are uneven, the wooden pad leveling crane shall not operate on the inclined ground or on the muddy and uneven ground. The well should pay attention to whether there are wires and other obstacles that affect operation.
2. Trial hoisting should be carried out before each operation. The heavy objects should be hoisted from the ground about 200 mm to test whether the brake is reliable and whether the straight leg is reliable.
3. When working, the wire rope should be lifted vertically. No inclined or horizontal lifting is allowed, otherwise, not only the weight will swing or other objects will collide, but also the crane will overturn.
4. When the crane is working at heavy load, the left hand rotation angle of the boom should not exceed 45. Slow rotation should be carried out and the amplitude of the boom should be avoided at the same time. Otherwise, it is easy to cause serious accidents such as falling arm folding over.
5. When hoisting heavy objects at high altitudes, a certain distance should be maintained between the hook and the pulley in order to prevent the overhead of the hoist and the back of the boom caused by the buried and broken steel wire.
6. In the process of lifting heavy objects, it is not allowed to pull the manipulator handle of the crane's leg. If it is necessary to adjust the leg, the weight should be dropped before adjusting.
7. It is forbidden to use a crane to lift and pull out unknown objects buried underground and objects solidified (frozen) on the ground and equipment, so as to avoid overload operation and cause accidents.
8. The brake of the overweight machine on rainy and snowy days is easy to fail, so the lifting hook must be slow. In case of six slow winds, suspension should be stopped.
Technical points of cantilever crane overload device
The cantilever crane overlifting operation process, no cylinder type overlifting device installation is simple and quick, but in the use process of more attention, operation technology is difficult; horizontal + vertical cylinder type overlifting device complex structure, high cost, assembly time-consuming, but easy to use, flexible operation, and can realize the overlifting weight stepless amplitude change; Compared with the former, the flat cylinder type has the advantages of simple installation and low cost, but its performance is similar to that of the non-cylinder type, but it can change steplessly after lifting the counterweight and leaving the ground.
Through the analysis of the operation process of overtaking operation, the following points should be achieved in the design process of overhanging device of cantilever crane:
(1) If the horizontal cylinder type can be stepless amplitude, it needs to be equipped with a length sensor. Otherwise, the positioning pin can be used to ensure the amplitude of overweight in a certain range.
(2) the micro motion performance of the cantilever crane is better than that of the single rope, and the stable speed of the single rope is less than 2m/min.
(3) the main variable amplitude force must be large and small. The force sensor can be installed on the luffing rope or the main swing plate.
(4) to install the angle sensor from the mast, and calculate the amplitude of the super mast through its value.
(5) The overhead device with vertical cylinder needs to be equipped with pressure sensors to check the force balance of the pull plates on both sides and display the force situation on the display screen. Users can choose whether to operate the two cylinders synchronously or adjust them separately.
Spring inspection method for cantilever crane
1. Butterfly springs should be checked every year or after 500000 times of braking action. Inspection method: first make the cantilever crane brake in full braking state, then gradually pour pressure oil into the hydraulic cylinder, so that the pressure in the brake hydraulic cylinder slowly rises, the brakes are loosened one by one under different pressures, recording the loosening pressure of different brake shoe, in which the difference between high and low oil pressures should not exceed 10% of the high working pressure. Otherwise, disc springs should be replaced in the brakes with low brake pressure.
2. Improvement of the connection mode between the brake shoe and the lining plate of the cantilever crane; 6 copper screws were used to connect the brake disc and the lining plate of the factory in the past, which not only reduced the contact area of the brake disc and reduced the service life of the brake shoe, but also caused the scratch of the brake disc by the loosening of the copper screws in the course of use. It is suggested that the site should be replaced by the insertion type, that The mouth is inserted into the lining board.
3. In the mine which is used under the weight, the mechanical brake can not be used entirely. This will cause the brake disc to heat up. Once emergencies occur, it will affect the braking torque and cause major accidents. The cantilever crane should adopt dynamic braking.
4, attention should be paid to pressing the brake shoe when replacing the brake shoe.
5. Whether the roughness of the brake disc is not enough or the deflection of the end face of the brake disc will increase the wear and tear of the brake disc.
6. The brake shoe must not be dipped in oil, and the middle disc brake must not be used without oil, so as not to reduce the friction coefficient of the brake shoe to affect the braking force.
7. The axial displacement of brake disc is large due to the wear of main bearing bearing bush of cantilever crane single rope hoist, which will accelerate the wear of brake disc. It is suggested to repair the main bearing bush.
Application and maintenance techniques of electric hoist
Lifting, removing, loading and unloading heavy objects, oil tank inversion welding, such as the installation and movement of various large and medium-sized concrete, steel structures and mechanical equipment, suitable for construction and installation companies, factories and mines of civil engineering and bridge construction, power, ships, automobile manufacturing, construction, highways, bridges, metallurgy, mines, slope tunnels, wellways Control mechanical equipment such as protection and other infrastructure projects.
Usage and maintenance:
1. electric hoists newly installed or dismantled and installed should be tested first and then several times. But do not turn on the electricity before the installation is completed.
2. Before normal use, a static load test should be carried out with a rated load of 125% and a lift of about 100 mm from the ground for 10 minutes to check if it is normal.
3. Dynamic load test is to make repeated lifting and left and right moving tests with rated load weight. After the test, check whether the mechanical transmission, electrical parts and connecting parts are normal and reliable.
4. In use, it is forbidden to use it in unacceptable environment, over rated load and rated closing times per hour (120 times).
5. When installing, debugging and maintaining, we must strictly check whether the limit device is flexible and reliable. When the hook is lifted to the upper limit position, the distance between the hook shell and the drum shell must be greater than 50mm (10t, 16t, 20t must be greater than 120mm). When the hook drops to the lower limit position, the wire rope safety ring on the drum should be guaranteed, and the effective safety ring must be more than 2 rings.
6. it is not allowed to press two hand button buttons that cause the electric hoist to move in opposite directions.
7. after the work is completed, the power gate must be opened and the power cut off.
8. The electric hoist should be operated by a special person. The operator should fully grasp the safety operation rules and strictly prohibit the inclined crane.
9. In use, the electric hoist must be inspected regularly by special personnel, and measures should be taken in time to find out the faults and carefully record them.
10. When adjusting the braking slip of electric hoist, the braking slip S < V/100 under rated load should be guaranteed.
11. Steel wire rope scrap standard: steel wire rope inspection and scrap standard according to CB/T5972-1986 "lifting machinery steel wire rope inspection and scrap practical specification" implementation.
12. Electric hoist must be used to maintain sufficient lubricating oil, and keep the lubricating oil clean, should not contain impurities and dirt.
13. Hard brushes or small pieces of wood should be used when putting oil on the wire rope. It is strictly forbidden to put oil on the working wire rope by hand.
14. when the electric hoist is not working, it is not allowed to hang heavy objects in the air to prevent deformation of parts.
15. in the course of using, if the fault is found, the main power source should be cut off immediately.
16. special attention should be paid to vulnerable parts in use.
17.10-20 tons of hoist after a long period of continuous operation, may appear automatic power failure phenomenon, which belongs to the motor overheating protection function, at this time can be reduced, after a period of time, after the motor cooling down can continue to work.
Four aspects should be noticed when choosing wire rope electric hoist.
1. Motor power: different electric hoist motor is not necessarily the same, the same 10t electric hoist motor may be 13KW or 7.5KW, customers can choose according to their different needs.
2. lifting height: electric hoist as a lifting tool will have strict requirements for lifting height. Therefore, when choosing and purchasing, you should first choose the height of lifting objects according to the height of your plant, the conventional lifting height is 6, 9, 12, 18, 24, 30m, special occasions can be non-standard design according to user requirements.
3. Lifting speed: Generally, the lifting speed of electric hoist is divided into single speed (8m/min) and double speed (8/0.8m/min). In general, the single-speed electric hoist (CD1) is often used without special requirements. If you need to be clearly positioned in the process of lifting heavy objects, it is easy to choose double-speed electric hoist (MD1). In general, the speed of your work depends on the efficiency, the higher the speed of the electric hoist, the more you can improve your efficiency.
4. Voltage: Electric hoist is used in all walks of life, so the voltage used by electric hoist is not the same, 380V industrial power also has 220V civil power, and even 440V, 60HZ, 380V, 60HZ and a series of non-standard power supply.
Causes and solutions of skidding of suspension cranes
1. The wheels and trolley tracks are stained with grease. Elimination method: remove oil pollution.
2, car wheels uneven pressure or small wheel pressure. Exclusive method: adjust wheel pressure of small wheel.
3, the trolley accelerates step by step. Troubleshooting: trolley accelerates step by step.
4, the motor power is large, or the resistance is unbalanced. Elimination method: replace motor debugging resistor.
Failure analysis and preventive measures of slewing boom brake
The brake is an important safety component of the rotary arm crane. It has the functions of preventing the falling of suspended objects and realizing the parking. Only the intact brake can guarantee the accuracy of crane operation and safe production.
In crane operation, brake force is insufficient, brake suddenly fails, brake wheel temperature is too high, brake gasket smoke, brake arm can not open and other mechanical failures.
The reasons for these mechanical failures are as follows:
1. Brake belt or brake wheel wear too much; brake with a small part of the fall off; the main spring is too loose; brake belt and brake wheel between the grease scale; movable hinge outside the stuck place or wear too much parts; lock nut loosening pull rod loosening; hydraulic push rod loosener impeller rotation is not flexible;
2. The brake gasket is severely or slightly off, or the long-stroke electromagnet is stuck, the main spring is invalid, or the main parts of the brake are damaged.
3, the gap between the brake and the gasket is too large or too small.
4. The hinge is stuck or the braking torque is adjusted too large, or the hydraulic push rod loosener cylinder is short of oil and mixed with air, or the oil used in hydraulic push rod loosening brake does not meet the requirements, or there is dirt between the brake disc and the brake wheel.
Regular inspection and maintenance of brakes, hoisting mechanism brakes must be once a shift, operating mechanism brakes to be once a day, the main check the following:
1, whether there is stuck and wear on the hinge, and whether the fastening points are loose.
2. Are the movements of the moving parts normal?
3, whether the hydraulic system is normal;
4, whether the wear between brake wheel and brake belt is normal and whether it is clean or not.
According to the inspection to determine whether the brake is normal, resolutely stop the operation of belt disease, while the brake to lubricate and maintain regularly. In order to ensure the safe operation of the crane, the brake must be regularly adjusted to ensure the working requirements of the corresponding mechanism.
Lubrication maintenance of travelling mechanism of cantilever crane
When first using the cantilever crane, the ventilation cap of the reducer should be opened to ensure good ventilation so as to reduce internal pressure. Check the height of the lubricating oil surface of the reducer before working. If it is lower than the normal oil surface, the same type of lubricating oil should be added in time.
The bearings of the wheels of the traveling mechanism of the cantilever crane are filled with enough grease (calcium-based grease) at the time of assembly. No daily refueling is required. The grease can be replaced once every two months by filling the oil hole or opening the bearing cover. The grease can be removed, cleaned and replaced once a year.
The open gear meshing parts of the cantilever crane are coated with grease once a week.
The reason that the electric hoist hook can not be repaired in the super low level chain ring
The hoist hook of the super low level chain hoist is made after forging and heat treatment.
Forging process is a method of metal hot working process. Forging process is the process of metal microstructure refinement and metal fiber arrangement. Heat treatment is to eliminate internal stress and further improve the mechanical properties of metal (can be simply understood as making the internal structure of metal more compact).
Repair welding is the whole process of partial melting, fusion and solidification of metals.
During repairing welding, the base metal of electric hoist hook with low clearance chain near the repairing welding is heated and cooled to varying degrees due to heat conduction. It is like a heat treatment of this part, which changes the structure and properties of this part, and most of the welding is aimed at the wear depression of the hook. The location is in the same straight line as the vertical dangerous section. Repair welding can refine the metal structure of the hook and destroy the sequential arrangement of the metal fibers, thus reducing the mechanical properties.