The defects of the lower tooth height and of larger pitch in thread portion of rolled pieces are prone to appearing when rolling thread shaft in cross wedge rolling. To solve this problem, changing the blank shape and size were tried. Two types of concave conical and round blanks are designed with concave conical blanks obtained by rolling in the cross wedge rolling. Because the design of the rolling die is simple, good precision of blank can be ensured. Multiple size types of blanks were designed and the rolling experiment was made in the rolling mill of model H630. By measuring the values of the tooth height and pitch, the effect of blank shape on thread shafts rolled in the wedge rolling were investigated carefully. The reasonable size range of the blank shape was obtained. The conclusions above pave the theoretical foundation for the in-depth study on this technology.
When rolling thread shaft in cross wedge rolling, forming quality of thread is affected by many process parameters such as the thread helix angle, which is a special and complex parameter. However, there is few study of the effect of the thread helix angle on thread shaft forming. In this paper how thread helix angle affects axial metal flow was analyzed from the perspective of rolling force and the forming process of thread shaft was simulated with different helix angles by the deform-3D software. Through the measurement of the point coordinates, the effect of the helix angle on the axial metal flow of rolled pieces was analyzed. Finally, the conclusion was obtained that helix angle causes the asymmetry of axial metal flow with small difference values for asymmetry and the axial metal flow of rolled pieces increases as the helix angle increases. The rolling thread segment can be ensured in the middle of rolled pieces by moving the blank a suitable distance in the reverse direction of the axial flow direction.
The study on forming helical tooth shaft processes in cross wedge rolling can contribute to the advantages of material-saving and efficient. Die tooth profile is an important process parameter of cross wedge rolling helical tooth shaft. Three kinds of forming process of die helical teeth were simulated by DEFORM-3D finite element analysis software to analyze three different die helical tooth. According to the tooth forming characteristics, the effects of three kinds of die tooth profile on forming of a polled piece were analyzed. When rolling a polled piece using the die with the same addendum width, it is convenient for die processing and the effect of polled piece forming is better; when using the die with the narrow front and gradually wider rear, the defects of uneven tooth bottom and larger pitch may happen. The rolling experiment was made by using the die with the same width at the tooth bottom. The results are in good agreement with the simulation. Therefore, we should use the die with unchanged addendum width, tooth height and the sidewall proportional increased when designing the die.
The static shear extrusion bonding experiment was carried out on the Q345 plates by the solid-state metal joining device with fast shearing. Meanwhile, based on the experimental and theoretical analysis, the influence of shear rate, the press quantity on the interface formation and microstructures evolution mechanism during shear extrusion bonding process were analyzed, and mechanical properties was investigated. The results show that with the increase of the press quantity, the interface formation divides into three stages, and the grain refinement is improved through dynamic recrystallization. The deformation work is provided by the bonding device, which is affected by shear rate. When the press quantity reaches 125%, the tensile strength of the specimens with high shear rate and low rate are 499.56MPa and 500.56MPa, respectively.
Analysis of the basic characteristic of cross wedge rolling forming process and the stress -strain research at various stages are summed up in order to obtain the basic rule of law and the metal flow regular during forming.
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