A Novel Method for Friction Coefficient Calculation in Metal Sheet Forming of Axis-Symmetric Deep Drawing Parts

Abstract

Friction is one of the important factors in sheet metal forming. It greatly affects dynamic behaviors of metal sheets and stress and strain distributions in the metal sheets. In this study, deformation characteristics, stress–strain distribution, and change law of symmetrical parts in the process of deep drawing are analyzed using a new theoretical model based on the plastic flow law and partitioning the forming area. In the model, the least-square method is used to linearize the friction coefficient in nonlinear problems and reverse the calculation of friction coefficients to interpret the friction coefficient. To evaluate the model, the friction coefficient in sheet metal drawing of axis-symmetric deep drawing parts under various friction conditions was measured using a self-developed measuring system. The comparison between the experimental results and the calculation using the model shows a good agreement. The results show that the drawing force increases with the increase in punch depth; the friction coefficient decreases with the rise in punch depth. The friction coefficient obtained by fitting is relatively stable, and the average error is less than 3%. Using the friction coefficient model in finite element simulation analysis, it shows that the thickness and blank shape errors are less than 5%. The novel method studied in this paper shows great significance in support for theoretical research, numerical simulation research, and sheet metal stamping performance evaluation.

Comparison of Friction Properties of GI Steel Plates with Various Surface Treatments

“…Lubricants 2024, 12, x FOR PEER REVIEW 3 of 14 relevant determination approach for the prediction of the technological characteristics of the deep drawing process [39,40]. The aim of this paper is to study the tribological and corrosion properties of a thin organic coating (TOC) based on hydroxyl resins dissolved in water and compare them with a standard Zn coating and a passivated one.…”

“…To determine the lubrication properties (the value of the friction coefficient on the contact surfaces of the die and the blank holder), the well-known formability test-the cup test-was used, which simulates the stresses on the material in a real deep drawing process [38][39][40]. This test can be used to describe the most frequent contacts in the tribological system between the tool (punch, blank holder, die), friction material (sheet metal specimen/product) and intermediate material (lubricant, oil, foil or permanent special coating on sheet metal)-Figure 3 [12,38].…”

“…By using the cup test, it is possible to model the stress of the contact surfaces during sheet metal forming [38]. The cup test offers a more CF-process-relevant determination approach for the prediction of the technological characteristics of the deep drawing process [39,40].…”

Research on Deep Drawing Technology for Tiny Parts Applied in the Electrical-Electronic Industry

“…Research projects on the influence of parameters such as blocking force and die geometry on the quality of stamping products, such as limiting earing height, wrinkling, and tearing [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. Research on the effects of friction to improve drawing efficiency has been published [17], [18], [19], [20], [21], [22], [23], [24], [25]. The influence of material parameters on the quality of stamping products has been reported [26].…”

Application of Collins’ upper bound theorem to upsetting processes

“…It has been shown that the solution coincides with an available relation if the friction factor is small enough. Meanwhile, the Coulomb friction law is often used for describing metal forming processes [Dubar et al, 9 Hwang and Chen, 10 Xia et al, 11 Schmidt et al, 12 and Bo¨hnke et al, 13 among many others]. Therefore, applying the theorem 7 to various metal forming processes is necessary.…”