Analysis of the Design and Manufacturing Technology of Large Compressor Shaft Rotors

As core equipment in industrial fields such as petrochemicals, energy and electricity, and metallurgical manufacturing, the performance of large compressors is directly related to the operating efficiency and economy of the entire production system. As the "heart" component of this key equipment, the design and manufacturing level of the compressor shaft rotor determines the reliability and service life of the whole machine.

The large compressor shaft rotor is a complex power transmission and energy conversion component, usually composed of a precision assembly of components such as the main shaft, impeller, balance disc, and coupling. Unlike conventional rotating mechanical parts, the compressor shaft rotor needs to withstand huge centrifugal forces, gas forces, and thermal stresses under high-speed rotation, while maintaining extremely high dynamic balance accuracy and dimensional stability. This extreme working condition places strict requirements on the material properties, structural strength, and manufacturing accuracy of the rotor.

From a functional perspective, the shaft rotor must not only realize the conversion of mechanical energy into gas pressure energy, but also ensure that the vibration characteristics of the entire rotor system during operation are within a safe range. The operating speed of modern large compressor rotors is usually between 3000-15000rpm, and some special applications can even reach more than 20000rpm. Under such high-speed rotation conditions, the dynamic behavior of the rotor becomes extremely complex, and even a small imbalance may cause severe vibration, leading to serious consequences such as seal failure and bearing damage.

The material selection of large compressor shaft rotors needs to consider many factors such as strength, toughness, corrosion resistance, and machinability. At present, the mainstream uses alloy steel materials, such as 34CrNiMo6, 42CrMo4 and other medium-carbon alloy steels. These materials can obtain good comprehensive mechanical properties after proper heat treatment. For corrosive medium environments, martensitic stainless steels such as 1Cr13, 2Cr13, or special materials such as duplex stainless steel are often used.

The influence of heat treatment process on rotor performance cannot be ignored. Quenching and tempering treatment (quenching + high-temperature tempering) is a key process to obtain good strength and toughness matching, which requires precise control of heating temperature, holding time and cooling rate. Large rotor forgings also often use stress relief annealing process to eliminate residual stress generated during processing and avoid deformation during subsequent finishing.

The processing process of large compressor shaft rotors reflects the top level of modern machinery manufacturing. Dozens of processes are required from rough machining to fine machining. The dimensional tolerance of key parts such as the journal and impeller groove is usually controlled within 0.01mm, and the surface roughness Ra value is required to be below 0.4μm. This precision requirement makes the selection of processing equipment particularly important. At present, high-rigidity and high-precision CNC turning and milling composite machining centers are generally used, combined with advanced online measurement systems to achieve real-time monitoring of processing quality.

Dynamic balancing technology is the core link to ensure the smooth operation of the rotor. Traditional high-speed dynamic balancing is mostly carried out in a vacuum chamber to reduce the influence of wind resistance; while modern laser dynamic balancing technology greatly improves the balancing efficiency and accuracy through non-contact measurement. It is worth noting that the balance of the rotor not only needs to consider the unbalanced amount in the rigid state, but also needs to analyze the influence of its flexible deformation on the balance state, which requires engineers to master complex rotor dynamics theory and use professional software for simulation calculations.

A complete quality inspection system is the last line of defense to ensure the reliability of the shaft rotor of a large compressor. In addition to conventional dimensional inspection, non-destructive inspections such as ultrasonic flaw detection and magnetic particle flaw detection are also required to detect tiny defects inside the material. In recent years, phased array ultrasonic testing technology has been widely used in the detection of key parts of rotors due to its high sensitivity and imaging capabilities. For important rotors, comprehensive mechanical properties tests are also required, including tensile, impact, and fatigue tests at room temperature and high temperature.