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| 汽车轻量化连接用自流钻螺钉挤压成形工艺研究 |
| Cold Extrusion Forming Technology of Flow Drill Screws for Lightweight Connection of Automobiles |
| Received:July 10, 2023 |
| DOI：10.3969/j.issn.1674-6457.2023.12.021 |
| 中文关键词: 自流钻螺钉 多工步冷挤压成形 成形力 数值模拟 工艺试验 |
| 英文关键词: flow drill screw multi-step cold extrusion forming forming force numerical simulation process testing |
| 基金项目: |
| Author Name | Affiliation | | SHI Tian-yin | Pan Asia Technical Automotive Center Co., Ltd., Shanghai 200120, China | | SHI Xiao-gang | Pan Asia Technical Automotive Center Co., Ltd., Shanghai 200120, China | | PAN Li | Nedschroef Fasteners Kunshan Co., Ltd., Jiangsu Kunshan 215300, China | | CAO Min-ye | School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China | | HU Cheng-liang | School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China |
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| 中文摘要: |
| 目的 针对自流钻螺钉现有工艺生产效率低、易产生晶粒粗大等问题，提出了一种新的多工步冷挤压成形工艺——利用模腔控制螺钉尾部形状，并验证了该工艺的可行性。方法 利用有限元软件DEFORM- 3D对提出的3种不同冷挤压方案成形过程中的金属流动规律、材料填充情况、成形力进行了数值模拟，讨论了方案一和方案二中锻造缺陷产生的原因，最后根据方案三的模拟结果设计了相应模具并进行了试验验证。结果 根据方案三成形出的自流钻螺钉充填饱满，第一道工序是将圆棒坯料一端直接挤压成螺钉特定的尾部形状，该工序所需成形力为42.4 kN。第二道工序是将螺钉头部镦粗，该工序所需成形力为58.2 kN。第三道工序是终锻成形，该工序所需成形力为287.4 kN。结论 通过有限元模拟，确定了自流钻螺钉三工步冷挤压成形工艺，提出了能够避免折叠产生的预制坯形状和模具结构，实现了自流钻螺钉尾部的可控成形。通过试验验证，形成了稳定的成形工艺窗口和可靠性较高的模具结构，实现了该产品的批量生产。 |
| 英文摘要: |
| The work aims to propose a new multi-step cold extrusion forming process, in which the shape of the screw tail is controlled by the die cavity, to address the problems of low production efficiency and easy occurrence of coarse grains in the existing production process of flow drill screws and verify the feasibility of this process. The finite element software DEFORM-3D was used to numerically simulate and analyze the metal flow pattern, material filling situation, and forming force during the forming process of three schemes. The reasons for forging defects in scheme 1 and scheme 2 were discussed. Finally, corresponding molds were designed based on the simulation results of scheme 3 for experimental verification. The flow drill screw formed in scheme 3 was fully filled, and the first process involved directly squeezing one end of the round bar blank into a specific tail shape of the screw. The required forming force for this process was 42.4 kN. The second process was to upset the screw head, which required a forming force of 58.2 kN. The third process was final forging, which required a forming force of 287.4 kN. Through finite element simulation, a three-step cold extrusion forming process for flow drill screws is determined, and a preform shape and die structure design to avoid folding is proposed, achieving controllable forming of the tail of flow drill screws. Through experimental verification, a stable forming process window and a highly reliable mold structure are formed, and mass production of the product is achieved. |
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