How to determine whether the NGW72-56 planetary gearbox needs preheating
To determine whether the NGW72-56 planetary gearbox needs to be preheated, a comprehensive judgment should be made based on three core dimensions: ambient temperature, equipment configuration, and operating status. The following five judgment criteria can be listed:
1. Directly determine based on the environmental temperature threshold
The ambient temperature is the core indicator that determines whether the gearbox needs to be preheated. It should be based on the lower operating temperature limit indicated in the equipment manual and refined according to the material characteristics of the components. For conventional models that have not undergone low-temperature modification, their core gears are made of 20CrMnTi carburizing steel, and the casing is made of gray cast iron. The minimum operating temperature that can be adapted is -10 ℃. Therefore, when the on-site ambient temperature is below -5 ℃, preheating operation is required. This is because when the temperature approaches -10 ℃, the viscosity of mineral gear oil will significantly increase, the flowability will deteriorate, and the impact toughness of metal components will decrease. The meshing impact during cold start is prone to cause microcracks. For models that have completed low-temperature transformation (upgrading low-temperature resistant steel and synthetic gear oil), the lower temperature limit for adaptation can reach -40 ℃. However, when the ambient temperature is below -20 ℃, preheating is still necessary because even if the fluidity of synthetic oil is good, the change in elastic modulus of metal components at extremely low temperatures will still cause an increase in meshing stress. Preheating can raise the temperature of the components and restore the mechanical properties of the material.
2. Indirect determination based on the condition of lubricating oil
The fluidity and condition of lubricating oil directly reflect whether the gearbox has safe starting conditions, and whether preheating is needed can be determined through visual inspection or oil monitoring data. For conventional models without oil temperature monitoring devices, an open oil port or oil level observation window can be opened to observe the flow status of lubricating oil. If the oil appears turbid, the flowability significantly deteriorates, or there are slight signs of solidification at low temperatures, it indicates that the viscosity of the oil has exceeded the safe operating range and preheating is necessary; For intelligent models equipped with oil temperature sensors, the oil temperature can be directly read. When the oil temperature is below 10 ℃, the oil film carrying capacity of the lubricating oil decreases, and it is unable to effectively lubricate the gear meshing surface and bearing raceway. At this time, the preheating program needs to be started until the oil temperature rises to above 15 ℃. In addition, if the lubricating oil is used for more than the oil change cycle, the fluidity of the deteriorated oil at low temperatures will further deteriorate. In this case, even if the ambient temperature is above the threshold, it is recommended to preheat for a short period of time to avoid lubrication failure.
