Analysis of Test Methods for Parts to Follow Relative Requirements

Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.

Analysis of the standardization application of MRP in SMEs

Order-oriented production is the main production method of some small and mediumsized enterprises(SMEs),which not only indicates that customer demand becomes the vane of enterprise production,but also puts high demands on the flexibility of production.Material requirements planning(MRP)is a modern enterprise management method based on basic databill of materials(BOM).For order-driven SMEs,MRP not only helps enterprises to complete material delivery in a timely manner,but also provides flexibility to meet customer needs.Standardization and MRP complement each other in enterprise operation,and they are effective in solving problems such as untimely material supply,undetermined procurement timing,and supply chain system jams.By studying the standardization application of MRP in enterprises,the article not only optimizes the standardization management system of enterprises,but also contributes to the high-quality development of SMEs.

Failure Mechanism and Material Requirements for Coal Lance in Blast Furnace

Pulverized coal injection（PCI） is a key technology in modern ironmaking by blast furnace（BF） and the life of injection lance has a great influence on PCI operation and on normal running of blast furnace.It is found that the main reasons for the failure of the lances are their outer surface oxidation and the inner surface erosion through monitoring some lances used in BF.The outer surface oxidation of the lances made of lCr18Ni9Ti is inevitable under high hot blast temperature condition through thermodynamics analysis.A mathematical model for calculating the temperature of common monocular coal lance had been developed according to the principles of mass and energy balance.Increasing temperature and flow velocity of the hot blast would cause a rise in the lance temperature.The influence of hot blast temperature is more obvious.The lance temperature would decline when compressed air flux increases.Conveying technology of dense phase pulverized coal is beneficial to extending lance’s life because decreasing solid-gas ratio would intensify erosion and burning loss.The anti-oxidation temperature of lance materials needs to be over 1000 ℃ for BF intensified smelting.In order to increase the resistance to oxidation of the coal lance’s outer surface,oxidation-resistant steel or Al coating stainless steel is the appropriate material for BF use.Employing the metal surface treatment technology to enhance the hardness of the coal lance’s internal surface could prolong the service life of coal lance