汽車製造品質管理制度導入之研究
—以高強度汽車鋼板點焊品質為例

全球汽車製造廠，為了使汽車品質提升及乘坐的安全性提高，汽車鋼板的耐撞擊能力需求亦相對的大幅提昇，同時為了響應全球縮減CO2排放量之政策，及車身輕量化以達到降低耗油量之趨勢。高強度鋼板運用在汽車構件上已是個趨勢，所以在超輕車身研究將著重於新材料、成形性及接合技巧三個方向來進行，而各種接合技術中又以電阻點焊製程被運用的最多，由於先進高強度鋼板仍存在著許多點焊品質及技術必須被克服。國內汽車廠近年來在新車型開發，已導入高強度鋼板構件，個案公司新導入車型也採用，因為高強度鋼板的點焊熔接條件設定，包含通電電流、通電時間、電極頭加壓力及電極頭先端徑等，與普通汽車鋼板差異甚大，為了確保高強度汽車鋼板的點焊熔接品質，急需深入探討高強度鋼板與點焊熔接相互關係，為了深入研究高強度鋼板之特性及熔接條件的改變對車體點焊品質及強度的影響，而進行研究熔接相關技術，藉由品管手法之改善及超音波檢測儀器判定，預低減點焊不良點及提升合格率。本研究係以個案研究方法，採取實地（Field）及實地實證（Field Empirical）研究的方式進行，依據Spot Welding 原理引用焦耳定律公式，針對高強度鋼板阻抗影響分析(鈑材厚度)，TIP先端徑變化阻抗影響分析，加壓力變化阻抗影響分析，以試驗片作測試並運用超音波檢測儀器驗證及運用品管手法，針對高強度鋼板之點焊品質作分析及對策，研究出最適合高強度鋼板之熔接條件設定規範。本研究將以實際車體作測試與驗證，首先就針對各作業站的鈑件組成項數盤點，製作不同高強度鋼板及一般鋼板之試驗片，共規劃出242項鈑金組合，以最適合高強度鋼板之熔接條件設定並實施點焊熔接，再藉由超音波檢測儀器判定，實際測試結果。將本次研究的結果，制定出高強鋼板最佳熔接條件規範標準及品質管理制度運用於高強度汽車鋼板上，提供個案公司及汽車同業車體組立參考使用。

關鍵字

高強度鋼板；點焊熔接；汽車製造業；品質管理制度

並列摘要

To global automakers, steel sheets’ higher ability to endure crash is needed to increase the quality and security of the automobiles. Meanwhile, to respond to the policy of diminishing CO2 emission and to reduce gasoline consumption by lightening the body of cars, applying high strength steel sheets to panel beating has become a trend. The lightest auto body research focuses on the new materials, malleability, and joining skills. Because there are still many challenges in spot quality and skills that should be conquered, spot producing process is the joining skill which is the most widely used. The domestic automakers have already applied the high strength steel sheets panel beating to developing new car styles and so as this case company. Different from common auto steel sheets, the spot welding conditions of the high strength steel sheets include electricity, power-on time, tip pressing, tip diameter and etc. To secure the quality of the high strength steel sheets’ spot welding, it’s important to know the interaction between the high strength steel sheets and spot welding. To deeply study the impact of the traits of high strength steel sheets and the changes of welding conditions on the quality and strength of spot, it’s important to study the related skills of welding which is to decrease the failed spot and increase the qualification rate by improving the quality management and ultrasonic wave detection. This research uses individual research methods of field and field empirical and adopts Joule’s law according to the Spot Welding principle. It also analyzes the resistance of the panel beating of high strength steel sheets, the changes of the tip diameter, and the changes of tip pressing. In addition, this research uses the test steel, the ultrasonic wave detection, and quality management to analyze the spot’s quality of high strength steel sheets in order to find out the most suitable welding conditions of high strength steel sheets. This research is going to test with the real auto. First, count the amount of the combination of the panel beating, and produce different test steels of high strength steel sheets and ordinary steel sheets. There comes out 242 kinds of combination of the panel beating. Then, adopt the most appropriate welding conditions of the high strength steel sheets and conduct spot welding. Finally, detect the panel beating under ultrasonic wave detection. According to the result of the research, this case company can work out the best regulations of welding conditions and quality management for high strength steel sheets, and apply them to our automobiles.