Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metal pressure processing > Rolling > Rolling mill machinery equipment > Rolling auxiliary equipment > Shears

Research on the Influence of Shear Design Parameters during Parallel Shearing Process

Author LuoZuo
Tutor WangDeLun
School Dalian University of Technology
Course Mechanical Design and Theory
Keywords Shear Design Parameters Shear Clearance Shear Zone Shear Stress-strainCurve Direction of the maximum shear stress
CLC TG333.21
Type Master's thesis
Year 2012
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In recent years, the medium-thick steel plate production has keeping on increasing,With the improvement of the plate cut quality, the production efficiency of scrap chopper was proposed higher requirements. At present in producing practice,the majority troubles such as cut vibration or blocking cut usually because of the unsuitable shear parameter especially the shear clearance. However,most of the technologies of, shear production were introduced from abroad. The foreign technical protection and little independent research lead to blank on the precise relationship between shear clearance and plate cut quality. Therefore,make a research on this subject is very important and necessary.In this paper,the action origin in the production difficulty from Chongqing Iron&Steel Company Limited that the reduction gearbox of chopper shear broken every three months.Through the experiment,the main reason is the unsuitable shearing clearance.Then based on cutting principle,finished some research on the relationship between shearing clearance and the characteristics of the fracture. Built on the physics and math model of the cutting process considering the influence of shearing stress.Provide some functions to find out the suitable clearance,to help highlight the quality.On purpose to analyze how the shear clearance influence plate cut quality,this paper put tensile and shear stress-strain curve and shear zone in one combine.First,compared the shear stress-strain curve with the tensile stress-strain,then built a simple model which can get the characteristic value.Then mapped the shear zone onto the shear stress-strain curve.The bright belt of the cross section was separated into two parts,the former one together with fillet belt belonged to the cut-in session,the latter one belonged to the slip session.With the strain compute by the simple tensile stress-strain model,the connection between relative shear clearance,mechanical properties of material and shear zone was figured out.Then used the balance of force to get the relationship between relative shear clearance and rotating angle of and the ratio of shear stress and lateral pressure.According to the fault zone,through analyzing plane-stress state,the direction of the maximum shear stress can be done.Depend on the research above,the methods to design the relative shear clearance were brought up.Apart from these,this paper also talked about two other influence elements which were the blade and the size of the steel.The blade could improve the late cut quality by means of keeping sharp and reduce the shear stress by incline a little angle from the vertical position.And both the thickness and highness of the steel would make a change to the fracture form. Finally, two examples illustrated that the relationship shear stress-strain curve and relative shear clearance,mechanical properties of material was improved. The design method of shear clearance in this paper is general, and can be extended to a series of similar products design. And it is significant for our country’s shear device independent research and development.

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