Abstract

Most technological processes of metal products manufactured by plastic deformation methods are associated with the formation of a self-balanced system of residual stresses in finished products. In many cases, the level of residual stresses is an important parameter that determines the product quality obtained as a result of plastic deformation. Reasons for the formation of residual stresses are diverse (inhomogeneity of plastic deformation, temperature field, phase transformations, etc.), which in their magnitude can exceed stresses from external loads. Currently, additional requirements are imposed on metal products in order to create machines and structures operating under high loads and speeds, sharp fluctuations in the parameters of the external environment. The experience of operating structures in various fields of technology and the results of numerous experiments show that residual stresses significantly affect the reliability and durability of machines and mechanisms. Based on the A.A. Ilyushin theory of unloading, analytical dependences were obtained for calculating the diagram of the change in residual stresses across the sheet thickness during bending under the rollers of leveler, as well as the springing angle. The diagram formation of residual stresses along the sheet thickness during leveling for the second, third and subsequent rollers of the leveler is considered. As a result of the superposition principle, it was found that the residual stress diagrams under the second and third rollers are added, forming a total diagram after the second and third rollers. For the fourth, fifth, sixth and subsequent leveler rollers, an algebraic addition of the residual stress diagrams also occurs. It is shown that for a 45 steel sheet with a thickness of 10 mm, a width of 500 mm, r/h = 200, the maximum residual tensile stress of 200 MPa is observed at a distance of Z/h = 0.3 from the neutral line along the sheet thickness. And in this case, the discrepancy between the experimental and calculated values of residual stresses is 10 –26 %, which makes it possible to recommend a method for calculating the residual stresses when leveling a sheet on a roller leveler for estimation of its quality.

中文翻译：

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滚筒矫直机的残余应力计算和板簧参数

摘要

通过塑性变形方法制造的金属产品的大多数工艺过程都与成品中残余应力的自平衡系统的形成有关。在许多情况下，残余应力的水平是决定由于塑性变形而获得的产品质量的重要参数。形成残余应力的原因是多种多样的（塑性变形，温度场，相变等不均匀性），其大小可能会超过来自外部载荷的应力。当前，对金属产品提出了额外的要求，以便制造在高负载和高速度，外部环境参数的剧烈波动下运行的机器和结构。在各种技术领域中操作结构的经验以及大量实验的结果表明，残余应力会显着影响机器和机构的可靠性和耐用性。根据AA Ilyushin的卸荷理论，获得了分析相关性，用于计算矫直机辊在弯曲期间在整个厚度范围内残余应力在整个板厚上的变化图以及弹跳角。考虑到矫直机的第二，第三和后续辊在矫直过程中沿板材厚度沿板厚度形成的残余应力的图表。作为叠加原理的结果，发现在第二和第三辊下增加了残余应力图，在第二和第三辊之后形成了总图。对于第四，第五 第六和以后的矫直辊，也会出现残余应力图的代数加法运算。结果表明，对于一块厚度为10毫米，宽度为500毫米的45钢板，r / h = 200，在沿板材厚度与中性线的距离为Z / h = 0.3时，观察到最大残余拉伸应力为200 MPa 。并且在这种情况下，残余应力的实验值与计算值之间的差异为10 – 26％，这使得可以推荐一种在辊式矫直机上矫平板材以估算其质量时计算残余应力的方法。