臺灣博碩士論文加值系統

擠伸製程是生產鋁擠型最有效的方法之一，其中擠伸模在製程中扮演著決定性的作用並直接影響擠伸產品的品質與成本。如今，擠型材的外型變得越來越複雜，這對模具製造商和設計者來說是一個巨大的挑戰。因此，為了滿足客戶的要求，創新的模具設計和製造方法至關重要。本研究的主要目的是結合經驗法則和HyperXtrude有限元素分析軟體對擠伸製程進行模擬，並開發出合理的模具結構與提出用於複雜鋁擠型(包括實心和空心外型)模具的設計準則。
首先，介紹了實心和空心模具的設計準則。本研究中亦建議使用數學公式來計算出模具的承面長度。然而在複雜的擠伸模具設計中，很大程度上取決於設計者的經驗和觀點。因此，本研究採用模具結構參數計算經驗公式用以提高模具的設計速度。
其次，本研究中介紹了兩種創新型的入口(Entrance)設計用於擠伸實心輪廓的擴增模(Spread die)。1) 類型1的入口為具有多階級的增徑(Spreader)。這種入料類型適合用於複雜外型或I型、L型、T型、U型和H型的鋁擠型的增徑擠伸(Spreading extrusion)。與使用傳統的單一階級的增徑相比，該類型有利於減小擠伸力、模具變形，同時利於製造、維護與材料流動平衡。解決了在擠伸相同輪廓時對不同模具類型(包括增徑模、袋口模和傳統的平模)對相關參數的影響。本研究亦詳細探討擠壓速度對這類型的模具的金屬流動和模具變形的影響。2) 類型2的入口為具有傾斜分流通道的結構。這是一種特殊的入口類型，其適用於擴增大型散熱器型材的擠伸。使用這種入料類型，擠伸力會顯著的降低，且擠伸後胚料的速度分佈優於傳統的入料類型。此外，針對這種入口類型，本文亦研究了該模具的最佳設計，例如修改模具配置；使用創新的入口、增加袋口和凸台。最後，亦提出了一種模具口輪廓的補償方法。
第三，本文提出使用獨特的模具結構用以擠伸壁厚較大的實心和空心型材的。1) 對於複雜實心的散熱器輪廓，設計了半空心供料口(Feeder)來改善金屬流動平衡。其結果顯示，模具中橋(Bridge)的結構和位置對擠伸的性能起著關鍵作用。亦研究橋的幾何形狀對擠伸參數的影響。為了獲得設計良好的模具，建議了四個設計階段，包括窗口(Porthole)的修正、袋口(Pocket)修正，承面長度(Bearing length)的調整和橋的倒角(Chamfered bridge)。2) 對於壁厚變化很大的複雜空心材，設計了一種特殊的心軸(懸浮芯)結構，該設計極大地改善了大壁厚位置處的金屬流動平衡。引入了兩個修改步驟來達到合理的模具結構設計，包括袋口的修正和特殊心軸的添加。使用穩態和瞬態模擬來研究入料口高度和焊接室寬度對擠伸參數和橫向焊道的影響。
最後，進行擠伸實驗用以驗證本研究所提出的四個模具設計建議。結果顯示，數值模擬可以很好地預測擠伸參數。使用建議所設計出的模具，可在兼顧公差和品質要求的下成功擠出產品。由此可知，本文成功提出了有效的解決方案且具價值的設計準則，且可實際應用於生產中。

Extrusion is one of the most efficient methods for producing aluminum profiles, in which extrusion die plays a decisive role in the success of the process and directly affects the extruded product's quality and cost. Nowadays, extrusion profiles are becoming more and more complex, which is a great challenge for die makers and designers. Therefore, to meet the strict requirements from customers, innovative approaches for die design and manufacturing are essential. The purpose of this dissertation is to develop rational die structures and propose design guidelines of the dies used for extrusion of complex aluminum profiles (including solid and hollow profiles) based on a combination of experience and finite element (FE) simulation by HyperXtrude software.
First, the design rules and guidelines of solid and hollow dies are introduced. The mathematical equation for the bearing length is suggested. The design of a complex extrusion die depends largely on the experience and viewpoint of the designer. Therefore, the empirical formulas for calculating the die structural parameters, which aim at increasing the designing speed, are proposed.
Secondly, this dissertation introduces two innovative entrance types of the spread die used for extruding solid profiles: 1) Entrance type 1 with a multi-stage spreader. This entrance type is suitable for spreading extrusion of complex or I-, L-, T-, U-, and H-shaped aluminum profiles. It is advantageous for reducing the extrusion force, the die deformation, favorable for fabrication, maintenance, and flow balance than the entrance type using a traditional single-stage spreader. An in-depth insight into the effects of different die types (including spread die, pocket die, and traditional flat-face die) on the related parameters when extruding the same profile is addressed. The influences of extrusion speed on metal flow and die deformation using these types of dies are also discussed in detail. 2) Entrance type 2 with an inclined diversion channel structure. This is a special entrance type, which is suitable for expanding the extrusion of large-size radiator profiles. Using this entrance type, the extrusion force is significantly reduced, and the velocity distribution in the extrudate is better than the traditional inlet type. In addition, optimal design approaches are studied for this entrance type, such as modifying die layout, using innovative entrance, adding pockets and bosses. Finally, a compensating method for the die orifice profile is presented.
Third, this dissertation proposes some effective solutions for extruding solid and hollow profiles with large variable wall thicknesses using unique die structures: 1) For the complex heatsink solid profiles, a semi-hollow feeder is designed to improve the metal flow balance. It is demonstrated that the structure and position of the bridge play a key role in the extruding performance. The influence of the bridge geometry on extrusion parameters is investigated. To obtain a well-designed die, four design stages are suggested, including porthole modification, pocket correction, bearing length adjustment, and chamfered bridge. 2) For the complex, hollow profiles with massive wall thickness variation, a special mandrel (suspended core) structure is designed. The proposed design solution strongly improves the metal flow balance at the large wall thickness position, which is the key to the success of the extrusion process. Two modification steps are introduced to achieve a reasonable die structure, including pocket correction and special mandrel addition. The effects of the inlet feeder height and the second-step welding chamber's width on the extrusion parameters and the transverse weld are also investigated using the steady-state and transient simulations.
Finally, extrusion experiments are conducted to verify four proposed die designs. The results show that the numerical simulations well predict the extrusion parameters. Using the proposed dies, the products can be extruded successfully with satisfying the tolerance and quality requirements in the first test extrusion. Hence, it is shown that effective solutions, valuable design guidelines, and instructions are successfully proposed, which can be useful in actual production.

中文摘要
Contents
List of Figures
List of Tables
Nomenclature
Chapter 1: Introduction
1.1 General introduction
1.2 Literature review
1.3 Motivation, scope, and structure of the dissertation
Chapter 2: Rules and Guidelines for Die Design and Numerical Modeling for Aluminum Extrusion
2.1 Initial parameters for the design process
2.1.1 Profiles and requirements
2.2.2 Die style, base die size, and extrusion press
2.2 Rules and guidelines of solid die design
2.2.1 Location of the die orifice of solid die
2.2.2 Feeder, pocket, and spreader
2.2.3 Bearing length of solid die
2.2.4 Run-out step of solid die
2.3 Rules and guidelines of hollow die design
2.3.1 Location of the die orifice of hollow die
2.3.2 Porthole and bridge design
2.3.3 Welding chamber of hollow die
2.3.4 Bearing length of hollow die
2.3.5 Run-out step of hollow die
2.4 Numerical modeling for aluminum extrusion
2.5 Evaluation criteria of velocity and temperature distributions
2.6 Extrusion simulation examples
2.6.1 Simulation of extrusion dies for simple solid profile
2.6.3 Simulation of extrusion dies for complex solid profile
2.7 Conclusions
Chapter 3: Multi-stage Spreader of a Spread Solid Die for Complex Thin-walled Aluminum Profile Extrusion
3.1 Introduction
3.2 Profile, die design, and FE modeling
3.2.1 Profile
3.2.2 The design of the spread dies
3.2.3 FE modeling for the spread dies
3.3 Simulation results and experiments of the spread dies
3.3.1 Simulation results of the spread dies
3.3.2 Experiments with the multi-stage spreader die
3.4 Numerical evaluation of the effect of die types in complex profile extrusion
3.4.1 The design of the flat-face and pocket dies
3.4.2 FE modeling for the flat-face and pocket dies
3.4.3 Simulation results
3.5 Conclusions
Chapter 4: New Design of Spreading Extrusion Die Entrance for a Large-Scale Aluminum Heatsink Profile
4.1 Introduction
4.2 Profile, initial die design, and FE modeling
4.2.1 Product profile
4.2.2 Initial die design
4.2.3 FE modeling
4.3 Simulation results and discussion
4.3.1 Simulation results of the initial die
4.3.2 The die design with the modified layout and new spreader structure
4.3.3 The die design with an added pocket
4.3.4 The optimal die design with added bosses
4.3.5 Die deflection
4.4 Experiments
4.5 Conclusions
Chapter 5: Extrusion Die Structure for Solid Aluminum Heatsink Profile with Large Variable Wall Thickness
5.1 Introduction
5.2 Profile, initial die design, FE modeling
5.2.1 Profile
5.2.2 Initial die design
5.2.3 FE modeling
5.3 Velocity distribution with the initial die design
5.4 Adjusting die structure
5.4.1 Resizing porthole
5.4.2 Modifying pocket profile
5.4.3 Adjusting bearing lengths
5.5 Effects of the port bridge structure and the welding chamber height
5.5.1 Effect of the welding chamber height
5.5.2 Effect of the port bridge parameters
5.6 The optimal die structure
5.7 Comparison between the optimal die and designed die without a port bridge
5.8 Extrusion experiment
5.9 Conclusions
Chapter 6: New Die Structure for Porthole Die Extrusion of Multi-hole Aluminum Profile with Large Variable Wall Thickness
6.1 Introduction
6.2 Profile, initial die design, FE modeling
6.2.1 Profile
6.2.2 Initial die design
6.2.3 FE modeling
6.3 Simulation results of the initial die design
6.4 Simulation results of the die optimization schemes
6.4.1 Simulation results of optimization scheme 1 (die design with modifying pocket)
6.4.2 Simulation results of second modification scheme (die design with adding special cores)
6.5 Influence of die structure
6.5.1 Influence of second-step welding chamber width
6.5.2 Influence of feeder height
6.6 The final die design and experiments
6.7 Conclusions
Chapter 7: Conclusions and future research
7.1 Conclusions
7.2 Future research
Vita
Publication
Acknowledgment
References

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