A study on The Effect of Tolerances and Forces on deformation of Mechanism

工業產品的競爭日益激烈，顧客對於產品品質的要求愈來愈高，低品質低價位的產品以漸漸失去競爭力，若要平衡產品品質與成本，則必須對產品的製造技術與設計過程著手改善，在產品設計的過程中，若要有效地控制產品精度與品質，就須從產品的公差設計、功能需求、配合精度著手。 有鑑於此，本文針對機械結構受力情況，以及機械結構本身的公差設計為考量，探討公差對機械結構受力變形所造成精度上的影響。文中先對機械結構進行公差分析，之後再對機械結構以有限元素法進行受力變形分析，隨後為造成的形態誤差，因此將公差分析所得之形態誤差加入原機械結構中，並重新進行受力變形分析，再將兩次的受力變形分析加以比較，最後將公差對機械結構所造成的誤差變位與受公差影響之受力變形分析結果予以結合，探討公差對機械結構造成的影響。研究結果發現，公差對機械結構所造成的誤差影響對於勁度較差之機械結構比受力來的明顯。文中同時以射出成型機之鎖模機構與模板機構以及IC銲線機之銲頭機構為實例說明此方法。As product competition and customer requirement on product quality become higher, product with low quality, though cheaper, loses its market day by day. High quality, however, often means high cost. It requires improvement on both product design and manufacturing to balance product quality and cost. To control product accuracy and quality, one has to start with functional requirement and tolerancing and fitting design. This thesis combines forced deformation and variation of components due to manufacturing tolerances to affect the accuracy of a mechanical structure under external forces. Tolerance stack-up of a structure by tolerance analysis and forced deformation by finite element method (FEM) are first introduced in this thesis. Shape variation of components due to manufacturing tolerances is then introduced to investigate the “ real ” structure, which is then analyzed by FEM to investigate the real deformation of the structure. Together with shape variation due to tolerances, the deformation of such a structure is then compared with the “ ideal “ structure to find the affects of manufacturing tolerances. The mold-clamping mechanism of a plastic injection machine and the soldering mechanism of an integrated circuit wiring machine are used in the thesis to illustrate the method. It is found that tolerance plays an important role in the deformation of a structure/mechanism with low stiffness.中文摘要Ⅰ 英文摘要Ⅱ 誌謝Ⅲ 目錄Ⅳ 圖目錄Ⅵ 表目錄Ⅹ 第一章 緒論1 1.1 研究動機1 1.2 實例說明2 1.3 文獻回顧5 1.4 研究方法6 1.5 本文大綱 8 第二章 公差分析9 2.1 公差表示法理論10 2.2 公差誤差與配合誤差模型21 2.3 公差累積理論23 第三章 機械結構之受力分析32 3.1 機械結構之有限元素分析33 3.2 實例說明35 第四章 機械結構受公差影響後之受力分析55 4.1 受公差影響之受力變形理論55 4.2 受公差影響後之機械結構受力分析61 4.3 結合公差變位與受公差影響之機構變形分析76 第五章 結論與未來展望83 參考資料87 附錄A 公差對銲線機構受力變形影響之探討90 附錄B 肘節機構各零件角度關係推導103 附錄C 鎖模機構以最大鎖模力受力變形狀況106 作者簡介11