The application of the crane digital control system and the preventive measures for the failure of the main oil pump coupling

<XNUMX> Application of crane digital control system

Plum-shaped flexible couplings are being built vigorously as an important part of road traffic under the background of rapid economic and social development in my country.In the construction of bridge engineering, bridge cranes play an irreplaceable role, which is the quality of bridge engineering.Therefore, it is necessary to innovate and optimize the structure of rotation, main beam, drive and operation to achieve the goal of optimized design of crane structure, thereby improving the output efficiency of equipment operation.In addition, build a digital control platform, fully prepare for data collection and analysis of crane dispatching operations, and the operating efficiency of the lifting system to build a good mechanized and digital operating platform for the on-site construction of bridge projects.

1. Data system

With the continuous development and maturity of digital technology, the use of digital technology to build an operating platform can improve the utilization efficiency of cranes.Through innovation and development, the use of digital technology in enterprise information management has become more and more mature, so that the operation and construction mode of the enterprise has been improved and improved, and then the operation of software and hardware has been integrated.Among them, operators are required to perform layout operations on the operating system according to the actual conditions of the bridge structure, implement the operations of equipment in each county, and ensure the consistency and accuracy of geographic data.

2. Network system

The complexity of the data authentication standards and the authority of the equipment structure service operation. If instructions cannot be passed, the operation screen of the system will not be able to start, which reflects the humanized characteristics of digital operation.In the digital system operation, the application of information processing technology can improve the dynamics of the display effect, and present operable functional modules for the operator from multiple angles.Set up an on-site reaction center to realize the networked data structure and guide the operation of the crane well.

3. Management system

Strongerness is the distinguishing feature of the operation mode of mechanized and digital equipment. In order to make the digital operation mode usable, the area is divided and investigated according to the corresponding utilization mechanism.In addition, it is necessary to make innovative adjustments to existing operating platforms, especially to clarify local regulatory responsibilities, implement and improve the digital operating liability system, improve corresponding target assessment standards, and stop and prevent illegal digital platforms from breaking the law. activity.

The hoisting machinery that adopts frequency conversion speed control can still use the traditional speed control method, such as the speed control of driving, still use the traditional cam controller, different gears give rise or fall direction instructions and multi-level speed instructions. Input to the control end of the inverter to realize direction control and speed regulation.The measure for the vibration of the variable frequency speed regulation system is to change the rigid coupling of the transmission system to an elastic coupling.

<XNUMX> Preventive measures for the failure of the main oil pump coupling

It is necessary to strengthen the inspection of the main oil pump coupling during the overhaul, especially when the main oil pump thrust pad is found to be abnormally worn.When the coupling surface is found to be worn, the coupling should be replaced in time and the cause should be found to avoid jamming during operation and causing accidents.

The following measures should be taken for the operation of the main oil pump coupling:

1. Improve installation accuracy

Improving the installation accuracy can reduce the circumferential deviation (sloshing) and end surface deviation (swing deviation) of the main oil pump rotor center line relative to the steam turbine rotor center line, thereby reducing the jamming or friction of the gear coupling due to the change of geometric position may.For the radial allowable deviation of the two shafts, if there is no end surface deviation, it can be> 1mm.However, the output torque of the gear coupling will decrease as the included angle α and radial deviation b increase.In the case of α=1°30' and rated speed, the output torque is only about 15% of the rated torque, so the installation and centering accuracy of the coupling rotor should be improved as much as possible.

The angle between the main oil pump rotor and the center line of the steam turbine rotor is not easy to measure in actual maintenance. It is often replaced by measuring its end surface deviation. Usually when the main oil pump is centered, the end surface deviation and the circumference deviation should be ≤0.03mm (high and low values ​​should be considered to be reserved Height difference), the output power of the coupling is basically unaffected at this time.

When finding the center in cold state, the centerline of the main oil pump rotor is 0.20~0.25mm higher than the initial centerline of the turbine.

l=Δt1·r·λ+h·λ·Δt2 where: l is the height of the center of the main oil pump higher than the center of the steam turbine, mmΔt1 is the temperature difference between the cold and hot states of the steam turbine rotor, ℃; r is the control turbine 1 The journal radius at the No. bearing bush, mm; λ is the metal thermal expansion coefficient, mm/(mm·℃); h is the height of the steam turbine front box to the No. 1 bearing bush recess, mm; Δt2 is the cold state at the No. 1 bearing bush of the steam turbine front box The temperature difference from the hot state, ℃.

2. Lubrication conditions of the coupling

The main oil pump of the steam turbine is lubricated with turbine oil. According to installation experience, most coupling lubricants are taken from the lubricating oil pipe.During maintenance, it was found that due to the thin tubing, the tubing often had to be bent during maintenance and disassembly. The bends would restrict the lubricating oil, and there were weld beads during butt welding of the lubricating oil pipes. If debris accumulates in the pipeline to cause pipe blockage, there is a risk of lubrication breaking. During on-site inspections, it was found that the coupling had lubricated failure due to this many times.For hydraulically regulated systems, the front tank oil has many paths, and the oil pipe is easy to bend. Pay attention to it during maintenance. Increase the pipe diameter of the main pipe section of the oil pipe to reduce the throttling loss in the pipeline, and it can also increase The pressure of the oil, such as the pressure oil from the outlet of the main oil pump, is throttled and then led to the coupling.

3. The sliding pin system is jammed

The jam of the sliding pin system is an important cause of the change in the elevation and lateral position of the main oil pump rotor. In the actual maintenance, the front box is connected with many pipes, especially the vertical pin is located in the lower part of the front box, and the front box needs to be lifted. , And it is not easy to notice the defect in this part, so the inspection and repair of the front box sliding pin system is often ignored during the inspection.In fact, the good expansion of the initial unit is also a measure to maintain the economic operation of the unit. In 2004, Unit 5 of a power plant had the phenomenon of load swing due to the elevation of the main oil pump caused by the lifting of the front box.Therefore, pay attention to the inspection of the sliding pin system during maintenance.

For the jam of the sliding pin system, you can improve the smoothness of the sliding pin surface, change the material, or apply a suitable lubricant such as graphite or molybdenum disulfide.At the same time, attention should be paid to the cleaning around the front box to prevent foreign matter from entering the sliding pin gap.

4. Coupling tooth surface hardness

The tooth surface hardness of the inner and outer gear rings of the gear coupling should reach 45~50HRC/40~45HRC under quenching conditions, and should be more than 500HV during nitriding, and the layer depth should not be less than 0.5mm; it is worth noting that part of the coupling When the coupling leaves the factory, the tooth surface hardness is insufficient. Therefore, when the coupling tooth surface is found to be worn, check whether the hardness meets the requirements, and at the same time, perform the hardness check when replacing the coupling.