Abstract

Cold-drawn calibrated steel is an effective workpiece for the manufacturing of low-stiff cylindrical parts such as shafts and axles. A high accuracy of the diametric size along the workpiece length, low surface roughness, and increased hardness and strength of the surface layer compared to hot rolled products allow the production of a variety of parts with high metal utilization and high machining performance. The main disadvantage of calibrated metal is the residual stresses that occur during pressure processing. To reduce or change the nature of the distribution over the cross section, we propose to use small plastic deformations in the product’s surface layer. Surface plastic deformation (SPD) methods known in practice usually lead to the curvature of non-rigid workpieces. To intensify the stress-strain state in the deformation zone, a method of orbital surface deformation is proposed. The orbital deformation scheme is a rod indenter (tool), one end of which is equipped with a ball tip that is in contact with the surface to be treated. The second end of the rod indenter rotates about the vertical axis, forming a conical surface in space with a certain angle at the apex. A deforming force acts along the rod axis. Based on the finite element modeling, we consider the effect of the main parameters of orbital surface deformation on the stress state in the deformation zone and residual stresses in the finished products. Compared with the traditional SPD process, the stress intensity during orbital surface deformation will increase by 10–15%. The residual compressive stresses formed in the surface layers reach 70–85% of the material tensile strength. The relative radius of the orbital rotation and the radius of the operating tool, at which the formation of maximal temporary and residual stresses is ensured, were established. At an increase in the frequency of the orbital rotation of the operating tool, the temporary and residual compressive stresses increase. In the second part of the paper, we provide information on a more effective method of surface deformation and on the change in initial residual stresses that are formed during the calibration of cylindrical rods.

中文翻译：

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通过表面变形改善校准钢的质量。第1部分：轨道表面变形过程中圆柱零件的应力状态的确定

摘要

冷拔校准钢是制造低强度圆柱零件（例如轴和轴）的有效工件。与热轧产品相比，沿工件直径的直径尺寸精度高，表面粗糙度低，并且表面层的硬度和强度更高，因此可以生产具有高金属利用率和高加工性能的各种零件。校准金属的主要缺点是在压力处理过程中出现的残余应力。为了减少或更改横截面分布的性质，我们建议在产品的表面层使用较小的塑性变形。实践中已知的表面塑性变形（SPD）方法通常会导致非刚性工件弯曲。为了增强变形区的应力应变状态，提出了一种轨道表面变形的方法。轨道变形方案是一种杆压头（工具），其一端装有与待处理表面接触的球头。杆压头的第二端围绕垂直轴旋转，在空间中以一定角度在顶点处形成圆锥形表面。变形力沿杆的轴线作用。基于有限元建模，我们考虑了轨道表面变形的主要参数对变形区应力状态和成品残余应力的影响。与传统的SPD工艺相比，轨道表面变形过程中的应力强度将增加10-15％。在表面层中形成的残余压应力达到材料抗拉强度的70-85％。确定了轨道旋转的相对半径和操作工具的半径，在此确保形成最大的临时应力和残余应力。随着操作工具的轨道旋转频率的增加，暂时的和残余的压缩应力增加。在本文的第二部分中，我们提供了有关更有效的表面变形方法以及圆柱杆校准过程中形成的初始残余应力变化的信息。