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Evaluation of sheet metal covers to improve tool life in forging

评估金属板覆盖层以提高锻造工具寿命

基本信息

批准号：
262370983
负责人：
Professor Dr.-Ing. Gerhard Hirt
金额：
--
依托单位：
Institut für Bildsame Formgebung (IBF)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/262370983?language=en
关键词：
Evaluation sheet metal covers improve

项目摘要

This research project within the German Brazilian research cooperation BRAGECRIM proposes a new method for wear protection in closed die forging using exchangeable sheet metal die covers. The aim of this project is the development of an inexpensive and easily exchangeable sheet metal die cover which is used to protect the engraving. Generally, the results of the first funding period proved that the proposed concept of die cover can be applied to reduce the tool wear and increase the die lifetime in closed-die forging. For an example geometry, the maximum thermal shock was reduced by 140 K and the main principal stress by 10% due to a reduction of the notch effect in the radius of the die. Based upon a die lifetime calculation, an increase of the die lifetime by more than 200% can be expected. Furthermore, in the first funding period, a FEM model was developed, which can realistically predict the material flow of the billet and the behavior of the die cover. The model was validated for different die geometries by forging experiments. Besides these positive results, the first funding period revealed problems like thinning and wrinkling which lead to a destruction of the die cover after just a small number of forging cycles. Both numerical and experimental investigation allowed to analyze the mechanisms for the observed phenomena. The wrinkling and thinning of the die cover are mainly caused by tensile stresses within the sheet resulting from different friction coefficients at the contact between billet and die cover, respectively, die cover and die. Furthermore, the first funding period focused on the investigation of simple die geometries involving strip-like die covers which do not have a self-stiffening 3D curvature. Related work has shown that these self-stiffening effects provide a realistic opportunity to overcome these problems. Therefore, in close cooperation with the Brazilian partner institute LdTM the main focus of the second funding period is put on the analysis of boundary conditions, die geometries and process chains, where the limitations observed in the first funding period do not prevent a successful application of the die cover concept. To eliminate the tensile stresses within the sheet, the influence of different friction coefficients at both contact surfaces will be investigated. In addition, an enhanced fixation of the sheet within the die will be tested in order to prevent a relative movement between the die cover and the forging die. Besides this variation of the boundary conditions, a second main aim will be the investigation of 3D die covers geometries offering a larger stiffness to reduce the undesired effects considerably. After the second funding period, the concept shall be progressed to a point where a transfer to industrial application is realistic. It is planned to cooperate with ThyssenKrupp Metalúrgica Campo Limpo Ltda.

德国巴西研究合作机构BRAGECRIM的这一研究项目提出了一种新的方法，使用可更换的金属板模盖在闭式模锻中进行磨损保护。该项目的目的是开发一种廉价且易于更换的金属板模具盖，用于保护雕刻。总的来说，第一个资助期的结果证明，所提出的模具盖的概念可以应用于减少模具磨损和增加模具寿命在闭式模锻。对于一个示例的几何形状，最大热冲击减少了140 K和主要的主应力减少了10%，由于减少了凹口效应的半径的模具。根据模具寿命计算，可以预期模具寿命增加200%以上。此外，在第一个资助期，开发了一个有限元模型，可以真实地预测坯料的材料流动和模具盖的行为。通过锻造实验验证了该模型在不同模具几何形状下的有效性。除了这些积极的结果外，第一个资助期还发现了一些问题，如减薄和磨损，这些问题导致模具盖在少量锻造循环后损坏。数值和实验研究允许分析所观察到的现象的机制。模盖的起皱和变薄主要是由于坯料与模盖、模盖与模具之间的接触处的不同摩擦系数导致的板料内的拉应力引起的。此外，第一个资助期的重点是研究简单的模具几何形状，包括带状模具盖，没有自加强的3D曲率。相关研究表明，这些自硬化效应为克服这些问题提供了现实的机会。因此，在与巴西合作伙伴研究所LdTM的密切合作下，第二个资助期的主要重点放在边界条件、模具几何形状和工艺链的分析上，其中第一个资助期观察到的局限性并不妨碍模盖概念的成功应用。为了消除板内的拉应力，将研究两个接触表面处不同摩擦系数的影响。此外，将测试板在模具内的增强固定，以防止模具盖和锻造模具之间的相对移动。除了边界条件的这种变化之外，第二个主要目标将是研究3D模具盖几何形状，其提供更大的刚度以显著减少不期望的影响。在第二个供资期之后，这一概念将逐步发展到能够实际转入工业应用的程度。计划与ThyssenKrupp Metalúrgica Campo Limpo Ltda合作。