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Strength Anlysis of the Piston-ringdie of Straw Briquetting Equipment

Author: WanZuoLei
Tutor: YuXinQi
School: Hebei University of Science and Technology
Course: Chemical Process Equipment
Keywords: Straw compression molding piston-ringdie strength stresses temperature
CLC: S226
Type: Master's thesis
Year: 2013
Downloads: 38
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Abstract

With the increasingly exhausting of conventional energy，people are becoming moreand more interested in biomass energy，and the straw biomass dense molding technologyis just a better method of the use of biomass energy. Because of its low energyconsumption, large output, high product quality and other advantages, piston-ringdie strawbriquetting machine becomes the main equipment of future biomass solidification.Piston-ringdie is the key component of straw briquetting equipment. Its service life is themain factor to affect the promotion of the piston-ringdie briquetting machine. This papermainly analyzes the strength of piston-ringdie of straw briquetting equipment.The experimental study has established the relations between the straw briquettedensity and impact factors. The results show that the molded product has smooth surface,suitable density, and the highest quality when its moisture content is about15%, themolding pressure is about60MPa and the virgin material size is10~20mm.The discussion on the biomass plastic deformation problems derived the piston-ringdieelastoplastic constitutive equations in the biomass molding process, and established thefinite element model of stress-strain and temperature fields in the molding process. Theauthor did finite element simulation of stress and strain fields in the piston-ringdiemolding process. The results show that in the same cross-section, the flow velocity nearthe center portion of material is faster than that of the surface material in contact with theinner wall of the die orifice. The part with the smallest flow speed (the edges and cornersof the piston-ringdie) is precisely the site of maximum stress value. Stress concentration isthe reason for the phenomenon that the briquetting finished edges and corners was torndown and blunt and the die orifice material is pelt off. The stress concentrationphenomenon get significantly improved when the edges and corners of the die orifice isrounded. The maximum reduction of the value stress is15.733MPa. The finite elementsimulation of the temperature field of piston-ringdie in the molding process shows that thepiston-ringdie of the edges and corners of the die orifice is rounded less tends to generatethermal stress, and is more suitable for biomass molding.Piston-ringdie can be affected by force and temperature. For this, the author did thethermo-mechanical coupling finite element simulation of the piston-ringdie, and got thedistribution of piston-ringdie coupling stress field, and that after making improvement. Bycomparing the two results, it proves that the distribution of the piston-ringdie stress field which has been improved is superior to the former. It also provides a theoretical basis forthe improvements of the core components–piston-ringdie of straw briquetting machine.

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