鎂合金板材溫間恆溫成形模具與工件之接觸分析

The Asperity Contact Analysis of Magnesium Alloys Sheet During Warm Isothermal Forming

楊宗憲(Tsung-Hsien Yang)

指導教授 ： 楊東昇

國立虎尾科技大學/工程學院/機械與電腦輔助工程系碩士班/碩士(2013年)

https://doi.org/10.6827/NFU.2013.00142

摘要

鎂合金在常溫下成形性不佳，需加熱來增加其成形性，因此鎂合金板材之溫間成形技術也漸受到重視。而鎂合金板材溫間成形過程中摩擦與潤滑扮演重要角色，其會影響其應力與應變分佈、成形性及表面形貌，而目前對於室溫下成形之模具與板材界面磨潤行為之研究較多，而本研究主要針對溫間恆溫成形過程中模具與鎂合金板材表面峰接觸行為及工件表面品質之研究。
本研究首先在不同溫度之恆溫狀況下，利用溫間板金磨擦試驗機，觀察模具與鎂合金板材在不同溫度且恆溫下之接觸行為及表面品質探討，包括進行純粹壓平、壓縮滑動等實驗，求得在不同參數下(如溫度、壓力、體應變率及相對滑動距離等)之接觸面積，其次得到不同溫度、壓力、體應變率及相對滑動距離下的表面粗糙度。另外藉由類神經網路建構在不同溫度、壓力、體應變率及相對滑動距離與接觸面積及表面粗度的預估模式。經由上述實驗可以得知在純粹壓平中當摩擦因子增加，接觸面積比會減少，而粗糙比則會增加，當壓平率增加，接觸面積比會減少，而粗糙比則會增加，當溫度越高時，接觸面比會增加，而粗糙比會減少。在滑動接觸中當摩擦因子增加時，接觸面積比會增加，而粗糙比會減少，當變率增加時，接觸面積比會增加，而粗糙比會減少，當溫度增加時，接觸面比會增加，而粗糙比會減少。

關鍵字

溫間板金磨擦試驗機 ； 表面峰接觸行為 ； 接觸面積 ； 表面粗糙度

並列摘要

Magnesium alloy under room temperature has poor formability. It needs to be heated to increase its formability, and therefore the warm forming technology of magnesium alloy sheets are getting more and more attention. During the warm forming process, however, friction and lubrication play an important part, affecting the stress and strain distributions, formability, and surface appearance. In the academic field, commonly available are studies on molds formed under room temperature as well as friction and lubrication between metal sheets, while this research is focused on the behavior of contact between the mold and magnesium alloy sheet surface peak as well as the quality of the workpiece surface.
To start with, under thermostatic conditions of different temperatures, this research uses a warm sheet friction tester to observe the behavior of contact between the mold and magnesium alloy sheet and explore the surface quality. The experimental tests include simple flattening and compressed sliding to get the contact areas with different set of parameters (e.g. temperature, pressure, volumetric strain rate, and sliding relative distance), and then get the surface roughness under these sets of parameters. Also, neural network is used to build a model to predict the contact areas and surface roughness under the different sets of parameters. The experiment results show that in the simple flattening process, the following rules apply: (1) increased friction factor reduces the contact area but increases the roughness; (2) increased flattening rate reduces the contact area but increases the roughness; (3) when the temperature gets higher, the contact area will be increased but the roughness will be decreased. In the sliding contact, the following rules apply: (1) increased friction factor increases the contact area but reduces the roughness; (2) increased variable rate increases the contact area but reduces the roughness; (3) when the temperature gets higher, the contact area will be increased but the roughness will be decreased.

並列關鍵字

warm sheet friction tester ； sheet surface peak as ； contact area ； roughness

參考文獻

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