This type of crane is proposed. The open gear transmission of the slewing mechanism is not dust-proof or the casing, the gear is completely exposed to the outside, and the external debris such as ash layer, sand, cinder, etc. is easily invaded by the gear teeth, and the lubrication is added. Poor, the teeth are easy to wear, there will be wear and tear on the surface of the broken teeth, pitting and other failure forms.
The two electric wide-track railway cranes have high utilization rate and are busy in operation. The names of the goods in operation are all bulk goods, and the working conditions are very poor. Due to the long-term intrusion of the ash layer, the gear teeth are worn more and more. The average operation is between 10,000 tons and 120,000 tons. The rotating planetary pinion is analyzed according to the cause of wear and over-limit. According to the site investigation, except for the gear teeth of one gear, the other small gears are worn due to the tooth surface. It is pointed or has a stepped shape and can no longer be used.
The wear failure form of the tooth surface appears so frequently, and the reason is analyzed. It is mainly manifested in the following two aspects: when the two gear teeth are not properly slid, a certain rolling friction force is generated.
By adding a certain amount of lubricating oil to the surfaces of the two friction pairs, the friction can be reduced, and in the case of poor lubrication, the friction coefficient between the teeth increases.
The increase of the relative frictional force increases the degree of squeezing between the tooth surfaces, so that the surface of the gear teeth will prematurely fall off, and the gear teeth will wear out.
The hardness of the tooth surface does not meet the requirements. During use, it has been found that the tooth surface of a planetary pinion is cut by the blade, and the material particles fall down piece by piece. Obviously, the material of the pinion and the rotating raceway ring gear The hardness is very different.
According to the design requirements, the materials of the planetary steamer and the rotating raceway ring gear are No. 1 ordinary carbon steel and No. 2, No. 1 cast steel. According to the requirements of the gear transmission on the performance of the gear tooth material, the tooth surface of the pinion gear and the point ring should be Hard, the tooth core should be tough, so in the process of adding, the quenching and tempering treatment is required, the hardness is reached, the tooth surface is also subjected to high frequency, and the Rockwell hardness reaches 01辫2.
However, due to various reasons during the processing, it is often the case that the strength of the material does not meet the requirements, the toughness is not enough, and the brittleness is too large, and the appearance of the wear failure form is taken for granted.
Impact of vibration shock This type of crane has manual operation, foot brake mechanism, and the driver brings different degrees of vibration shock to various mechanisms due to the influence of proficiency during operation.
According to the theory of vibration mechanics, the above-mentioned upper point wheel and the point map will generate compressive stress, and the metallographic structure of the component will be destroyed, and the hardness and rigidity of the natural material will be reduced.
Strength analysis In order to ensure that the gear transmission has sufficient working ability under specific working conditions, it will not be invalidated during the whole working process, and its service life must be improved. The root bending fatigue strength and the point contact fatigue strength of the wheel must be ensured. .
Next, a specific analysis and calculation are made on the meshing strength of the row 3 small point wheel and the rotary track point circle of the electric rail railway crane slewing mechanism.
The number of teeth of the conditional planetary pinion is known, the tooth width is 4, the diameter of the circle is 5) 6) 748, the tooth angle.
The maximum circumferential force transmitted by the second guard is 9 2 2; less =, the yield limit stress is under the action of the torsion moment transmitted by the pinion, and the direction of the force is perpendicular to the point when the tooth point is restored to a positive pressure Α The facial paralysis can be obtained according to the principle of decomposition of force.
When the two gears are in transmission, when the gear teeth are engaged into a single tooth, all the loads act on a pair of wheel points, and when the load acts on the tooth tip, the root stress is the largest, and the gear teeth are in the most dangerous state. .
Therefore, we should calculate the bending strength of the root by the maximum point at which the load acts on the single tooth pair.
The force of the unit tooth when the tooth top is engaged. In the tooth root danger profile Î. The compressive stress 1 and the bending stress 分别 are respectively determined, and the compressive stress 1 is negligible according to the state calculated by the above selection.
For the number of tooth points when the load acts on the top of the tooth, for one tooth number, Α6 should also consider the stress concentration caused by the transition fillet. Therefore, multiply a stress correction number in the original expression according to the number of teeth.
Therefore, it meets the bending strength requirements. In addition, in the design process, in order to prevent the occurrence of tooth root bending fatigue phenomenon, the bending fatigue strength of the gear teeth is reduced.
Tooth surface contact strength analysis According to the reasoning of the Hertz formula, the node is taken as the calculation point of the tooth surface contact strength, so it is calculated according to the tooth surface contact strength.
In order to ensure this condition, the conditions that should be met during design are as follows: To meet the condition of the tooth surface contact fatigue strength, the diameter of the pinion index circle should meet the requirements indicated above.
Precautionary measures From the above strength analysis, it can be concluded that the gear strength analysis design of this kind of structure is consistent with the occurrence of some quality 3 common diseases in the concrete construction process, affecting the safety of the structure, how to eliminate the quality of the three-way disease to the utmost extent. To ensure the safety of the engineering structure, it is urgently needed for every on-site technician. This paper discusses the causes and prevention measures of the quality of the three-way disease in concrete engineering.
The honeycomb structure concrete structure appears to be loose, less mortar, and many stones. The gap between the stones forms a honeycomb-like hole.
The reason is mainly due to improper concrete mix ratio or incorrect metering, resulting in less mortar, insufficient concrete mixing time of stone, no uniform mixing, poor workability, improper vibrating and improper feeding or unloading. Collusion concentrates the stones, causing the stone mortar to be separated from the concrete without delamination, vibrating, or leakage, or the vibration time is not enough. The gap of the template is not blocked, the cement slurry is densely packed, and the used stone is too large. Or the slump will continue to fill the small foundation, the column, and the root of the wall without any intermittent intervals. The measures for prevention and control strictly control the concrete mix ratio, and often check to ensure accurate measurement and uniform concrete mixing.
If the height of the concrete is more than 4, a stringer or chute should be provided. The watering should be layered and stratified, and the layered vibrating to prevent leakage. The formwork joints should be tightly closed. During the watering, the formwork support should be checked at any time to prevent leakage.
Foundation, column, wall root training should be poured in the lower part of the interval, after the sinking, then the upper concrete is poured to avoid the "rotten neck".
Treat the small cells with disease. After washing, clean or compact with cement mortar. Large honeycomb, chisel loose loose particles at the honeycomb. After brushing, the mold is carefully filled with fine stone concrete. Deep honeycomb, if it is difficult to remove, can grout the slurry pipe, exhaust pipe, surface mortar or concrete, and then grout the cement.
On the surface of the concrete surface, there is a lack of slurry and many small pits and pittings to form a rough surface, but no steel bar is exposed.
The reason is mainly due to the rough surface of the template or the adhesion of cement paste and other debris that has not been cleaned. The concrete surface is damaged when the mold is removed, and the template is not watered or wet enough.
The moisture of the concrete on the surface of the component is sucked out, so that the concrete loses too much water, the joint of the pockmark template is not strict, the local slurry is not uniformly coated, or the partial leakage brush or the release agent fails, and the concrete table and the template are bonded. The concrete on the surface of the pockmark is not vibrated, the bubbles are not discharged, and the pitting is stopped on the surface of the template.
The surface of the control measures shall be cleaned and cleaned. Do not stick dry and hard water mortar and other debris. Before pouring concrete, the formwork should be fully wetted by watering, the gap between the board and the board, the application of linoleum paper, putty, etc., and the template release agent should be long-lasting. The brush should be evenly painted, and the concrete should not be leaked. The concrete should be layered and evenly vibrated to eliminate the air bubbles.
1 The surface of the disease treatment is painted, it can be left untreated, and the surface is not painted. After the water is fully wetted in the surface of the pockmark, the original concrete is used to mix the stone mortar to smooth the surface.
The hole phenomenon concrete structure has large-sized voids inside, and there is no concrete or honeycomb in particular, and the steel bars are partially or completely exposed.
The main problem with this wear phenomenon should be poor lubrication, vibration shock, and the strength, toughness, and hardness of the material.
To prevent this phenomenon from appearing, it is mainly to prevent the occurrence of several situations listed above. Several preventive measures are proposed to prevent the driver's proficiency in practice, and to reduce the impulse generated during the operation to reduce the gear room. During the installation process, the parallelism and verticality between the vertical wheels of the slewing mechanism are grasped to prevent the eccentric wear between the teeth and prevent the occurrence of unbalanced friction. During the processing, the strength and toughness of the material Degree and hardness should meet the technical requirements to develop a reasonable process. Strengthen the lubrication between the teeth to do the daily maintenance of the machine.
Because it is an open gear transmission, the working conditions are very poor, so each class should be well lubricated and maintained at any time.
Regularly add grease to prevent dry friction from removing ash between the teeth in time, to prevent the amount of oil from being squeezed between the teeth, and the lubricant film has the ability to stage and absorb. Do the fastening work of the connecting parts in time.
Because it is hand-operated, the foot brake structure, the connecting bolt is very easy to loose, and it is easy to generate a certain vibration shock. Therefore, the inspection work should be strengthened, and the looseness of the connecting member should be found in time to take the fastening in time.
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