Blade Lock Ring of 4th Stage Compressor Rotor: Failure Investigation

Present work describes the failure investigation of blade lock ring of 4th stage compressor rotor. The lock ring is fabricated from martensitic stainless steel. The microstructure of failed lock ring is tempered martensite. It shows non-metallic inclusions with three distinct shapes namely, elongated (MnS), globular (Al2O3) and complex shaped (oxy-sulphide). The corrosion pits and corrosion debris are observed in un-etched microstructure and fracture surface, respectively. The tree like branching cracks has observed at several places near surface. These cracks have initiated from the corrosion pits and then propagated inside the material. The interface of inclusions and matrix has also acted as crack initiator. The lock ring has initially suffered pitting corrosion in service and then cracks have propagated inside the material by stress corrosion cracking.

Research on Calculation and Analysis of Clamping Force of Power Cut Self-Locking Device

Self-locking clamping device is an important part of self locking wind power hydraulic cylinder. When the wind power system is shut down, the hydraulic cylinder must be reliably locked. This paper mainly studies the principle of self-locking device, the calculation of clamping force, the performance factors and the analysis of the elastic deformation force of the lock ring in order to meet the performance requirements of hydraulic cylinder in the process of wind system lock.

Machining and its Influence to Surface Quality of Machine Parts

A number of machine parts are provided with design notches for the mounting of lock ring, position of bearing, and cross over sub of diameters etc. These elements significantly affect the durability of machines parts and their influence is inherently implemented into their design. The question is machining itself, particularly ambient surface finishing and intrinsic notch element. The changes and behaviour of machined surface form also very interesting part of paper and particularly under load. A number of new findings concerning the influence of machining on durability of machine parts both under dynamic load and the cyclic tensile, bending at rotation and torque were discovered in this research. The findings are important for further development, mainly related to car and aviation industries.

Evolution Regularity of Temperature Filed in Hot Power Backward Spinning for 7075 Cast Aluminium Alloy Tube

The spinning temperature is one of key factors affected the uneven deformation during the hot power backward spinning for brittle material tubes, such as cast 7075 aluminium alloy tube. To analyze the evolution regularity of temperature filed in the spinning process, a 3D thermo-mechanical FE model of the process is developed under ABAQUS/Explicit environment. Then, the evolution of temperature filed during the process is analyzed based on the FE model. The results show that: The contact areas temperatures between lock ring, spinning rollers and tube decrease sharply during the initial spinning stage. The high temperature region is transferred from unformed zone of the tube to the contact area between spinning roller and tube. In the spinning zone, the temperature of internal surface of the tube is apparently higher than that of outer face.