近幾年來，3D列印領域快速發展，應用的範圍也越來越廣，如生醫、汽車工業及航太工業之相關模型或零件製作等。雖然3D列印之成品的製程方式與機械加工相比，相對容易許多。但3D列印成品之機械性質卻也相對比較脆弱。因此，為了改善此問題，較常見的研究方式是針對列印材料、填料路徑、建模網格、改變加工環境與參數等方向探討影響機械性質之因素。相比之下，較少人探討以雙股螺旋之塑料結構及以梯形與平行四邊形之塑料組成3D列印成品，對其是否能得到較好之機械性質。
因此，本文提出一種可旋轉式之噴嘴，且噴嘴分別設計單一出料孔之單孔式噴嘴及具有兩個出料孔之兩孔式噴嘴。對單孔式噴嘴施以旋轉，可對擠出之塑料施以扭矩改變塑料之結構，甚至讓塑料產生捲曲;對兩孔式噴嘴施以旋轉時，則可將分別從兩出料孔擠出之塑料絞在一起，形成雙股螺旋結構之塑料。此外，本研究亦設計分別具有平行四邊形及梯形出料孔之兩種噴嘴，透過這兩種形狀之出料孔，可改變擠出之塑料形狀，分別形成外形為平行四邊形及梯形之塑料
實驗架構是將單孔式噴嘴及兩孔式噴嘴在以不同轉速的情況下製作試片，及分別使用平行四邊形及梯形出料孔之噴嘴製作試片，再以拉伸試驗之結果比較試片間之差異性。
由實驗結果來看，若是以單孔式噴嘴在不同轉速下製作試片，以無旋轉，即正常擠料之情況製作之試片會有較高的抗拉強度，且抗拉強度隨噴嘴轉速越快，會隨之降低。正常擠料之平均拉伸強度分別與以25 rpm、50 rpm及150 rpm之轉速製作之試片的平均拉伸強度相比，分別高出6.27%、10.88%及12.87%。
若是以兩孔式噴嘴在50 rpm及150 rpm之轉速下製作試片，同樣也會有轉速越快，抗拉強度隨之降低的趨勢，且其各試片之抗拉強度均低於以單孔式噴嘴製作之各試片。將結果與以單孔式噴嘴之正常擠料之試片平均抗拉強度相比，分別相差42.25%、66.75%。
而分別以梯形及平行四邊形出料孔之噴嘴製作之試片，將兩者之結果與以單孔式噴嘴之正常擠料之試片平均抗拉強度相比，仍以單孔式噴嘴以正常擠料製作之試片會有較高之抗拉強度。正常擠料之試片的平均拉伸應力分別比以梯形及平行四邊形出料孔之噴嘴製作之試片的平均拉伸應力依序高出4.69%及14.15%。
由實驗結果可推斷，試片內部之空隙、表面不規則之空洞及扭曲、雙股螺旋之塑料結構均會是造成試片之抗拉強度降低之原因。

In recent years, the field of 3D printing has the rapid development and its applications are more and more widely, such as creating the models for industries of automotive and aerospace and health. Although the process of 3D printing is easier than machining, the product of 3D printing are relatively fragile and brittleness.
In order to improve this problem, the most common research focused on the exploration of the factors that affect the mechanical properties, such as filament materials, raster orientation, meshing structure, and varied process environment. However, few studies explored whether the product made by twisted plastic structure and that made by trapezoidal or parallelogram plastic shape can obtain better mechanical properties of the 3D printing’s product .
This study proposes a rotatable nozzle, and also designs two different types of the nozzle. One is called single-channel nozzle, which has a single channel at the end of the nozzle. The other is called two-channel nozzle, which has two channels at the end of the nozzle. Different plastic structure of the product can be obtained by varying the rotating speed of nozzle. While the single-channel nozzle is rotating, the curl structure can be obtained; while the two-channel nozzle is rotating, the twisted structure can be obtained.
In addition, the study also designs two kinds of channel geometry of nozzle. One is trapezoid, and the other is parallelogram .We can obtain the plastic shapes with trapezoid and parallelogram through these two kinds of nozzles.
The objective of this study is to investigate the difference of the mechanical properties between the specimen made by various rotating speed of single-circular channel nozzle and two-circular channel nozzle. Besides, the study also investigate the difference of the mechanical properties between the specimen made by various channel geometry with no rotation.
According to the experimental results of the single-channel nozzle, the specimen has the best tensile strength without rotation, while the tensile strength would decrease as the rotating speed increases. The average tensile strength of the specimen made by the nozzle without rotation is higher than the specimen made at the rotating speed as 25 rpm,50 rpm and 150 rpm by 6.27%, 10.88% and 12.87%.
According to the results of the specimen made by the two-channel nozzle at the rotating speed as 50 rpm and 150 rpm, the same tendency has occurred with the results of the specimen made by the single-channel nozzle. The specimen made by the two-channel nozzle at the rotating speed as 50 rpm and 150 rpm are both more fragile than the specimen made by the single-channel nozzle. The above results are decreased by 42.25% and 66.75% respectively compared with the average tensile strength of the specimens made by the single-channel nozzle without rotation.
According to the results of the specimen made by the nozzle with trapezoidal channel and that with parallelogram channel. The specimen made by these two kinds of nozzle are also brittle than the specimen made by the single-channel nozzle. The above results are decreased by 4.69% and 14.15% respectively compared with the average tensile strength of the specimens made by the single-channel nozzle without rotation.
The experimental results show that voids in the specimen, irregular gaps on the surface of the specimen and plastic structures with both distortion and twisted would be the cause of reduced tensile strength of the specimen.

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