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塑性变形时金属的流动方向是压力加工中经常遇到的一个重要问题。分析矩形毛坯在平砧间镦粗时金属的流动对研究金属流动方向有较大的代表性。C.N.古布金在1947年曾提出了“最小阻力定律”,后来塔尔诺夫斯基1954年对矩形毛坯在不同摩擦条件下镦粗,给出了三种流动图形。本文结合大量的试验和计算分析,认为金属的流动方向不仅与摩擦系数有关,而且矩形坯料的长宽比对金属的流动方向有更大的影响。本文在试验结果的基础上进行了初步的理论分析,认为:1) 研究金属的流动方向问题时,应当首先从分析金属的变形出发。一质点的流动方向不仅与该点的应力应变状态有关,而且相邻金属对该质点的流动方向也有较大的影响,即金属的流动是取决于整个变形体内的应力场情况;2) 矩形毛坯镦粗时,在水平投影面上金属质点主要沿最大主应力(代数值) 的方向外流(或者说,金属质点主要向最大主应力增大(代数值)的方向流动),但与最大主应力方向有一定偏离,其偏离的程度与中间主应力的相对大小以及相邻金属的影响有关。
The direction of metal flow during plastic deformation is an important issue often encountered in pressure machining. The analysis of the flow of the metal blank when the rectangular blank is upset by the flat anvil is more representative of the research direction of the metal flow. C.N. Gubujin proposed the “law of least resistance” in 1947, and later Tarnofsky upset the rectangle blank under different friction conditions in 1954, giving three flow patterns. In this paper, a large number of tests and calculations show that the flow direction of the metal is not only related to the friction coefficient, but also the aspect ratio of the rectangular billet has a greater influence on the flow direction of the metal. Based on the experimental results, this paper carries out a preliminary theoretical analysis, which shows that: 1) When studying the flow direction of metal, we should start with the analysis of metal deformation. The flow direction of a particle is not only related to the stress-strain state of the point, but also the adjacent metal has a greater influence on the flow direction of the particle. That is, the flow of metal depends on the stress field in the whole deformation body. 2) When upsetting, the metallic particles mainly flow outward in the direction of the maximum principal stress (in other words, the metallic particles mainly flow toward the direction of maximum principal stress (algebraic value) on the horizontal projection plane), but the maximum principal stress The direction of a certain deviation, the extent of its deviation and the middle of the main stress of the relative size and the impact of adjacent metals.