【摘要】：超聲技術(shù)是集物理學(xué)、振動學(xué)、聲學(xué)等多學(xué)科交叉的一門新技術(shù),隨著科學(xué)界對超聲技術(shù)研究的深入,超聲技術(shù)在生物醫(yī)學(xué)、材料科學(xué)等領(lǐng)域得到廣泛應(yīng)用。將超聲技術(shù)應(yīng)用于聚合物注射成型過程中,發(fā)揮超聲在降低熔體粘度,提高塑件成型質(zhì)量方面的優(yōu)勢,成為注射成型的一種新方法。但是超聲振動如何影響聚合物充模流動,以及其對聚合物充模流動的作用機理仍不清楚,本文針對這個問題,提出利用可視化示蹤法,探討超聲振動對聚合物流動過程的影響。 本文以矩形平板塑件為研究對象,設(shè)計集超聲外場作用與可視化技術(shù)的注塑成型模具,實現(xiàn)一個模具上多位置超聲激勵的組合施加,利用此模具對聚丙烯(PP)材料進(jìn)行不同超聲功率和注射速率參數(shù)下的注射成型實驗,結(jié)合示蹤粒子標(biāo)記法和多項式數(shù)據(jù)擬合,研究超聲振動對熔體流動軌跡、塑件收縮方向以及熔體流動速度的影響。結(jié)果發(fā)現(xiàn),超聲振動一方面使得熔體在型腔內(nèi)更長距離上保持直線流動,冷卻階段塑件收縮平衡點位置向型腔末端移動；另一方面,能夠在一定程度上促進(jìn)PP熔體前沿的流動,最大提高幅度為35.2%。同時,前沿熔體流動速度曲線呈先降低,后升高,再降低,再上升,最后下降的變化趨勢。 結(jié)合示蹤粒子標(biāo)記法和Kringing插值法提出一種充型流動速度場的表征方法,實驗數(shù)據(jù)表明,一方面,熔體充模過程速度分布呈中間高,兩邊低,近澆口高,遠(yuǎn)澆口低的變化趨勢；施加超聲振動后,熔體流動速度增大,沿流動方向流動速度變化梯度減小。另一方面,從熔體流動速度的大小以及速度分布的均勻性角度上考慮,lmm塑件注射成型時,800W功率超聲對型腔內(nèi)熔體流動速度的提升最明顯,600W、400W、100W次之,200W功率超聲對流動速度的提高幅度最��；3,5mm塑件注塑成型時,200W功率超聲對型腔內(nèi)部速度場的改善最為顯著,800W、1OOW次之。
[Abstract]:Ultrasonic technology is a new interdisciplinary technology in physics, vibration, acoustics and so on. With the development of ultrasonic technology in science, ultrasonic technology has been widely used in biomedicine, material science and other fields. The application of ultrasonic technology in polymer injection molding process has become a new method for injection molding, which brings into play the advantages of ultrasonic in reducing melt viscosity and improving the molding quality of plastic parts. However, how ultrasonic vibration affects polymer filling flow and its mechanism of action on polymer filling flow are still unclear. In this paper, a visual tracer method is proposed to study the effect of ultrasonic vibration on polymer flow process. In this paper, the rectangular plate plastic parts are taken as the research object, and the injection molding mould with ultrasonic external field action and visualization technology is designed to realize the combination of multi-position ultrasonic excitation on a mould. The injection molding experiments of polypropylene (PP) materials under different ultrasonic power and injection rate parameters were carried out by using this mould. The ultrasonic vibration effect on melt flow trajectory was studied by combining the tracer particle marking method and polynomial data fitting. The influence of shrinkage direction and melt flow velocity of plastic parts. The results show that, on the one hand, ultrasonic vibration keeps the melt flowing at a longer distance in the cavity, and the equilibrium position of the plastic part shrinks to the end of the cavity in the cooling stage, on the other hand, it can promote the flow of the PP melt front to a certain extent. The maximum increase was 35.2a. At the same time, the front melt flow velocity curve decreases first, then increases, then decreases, then rises, and finally decreases. Combined with tracer particle marker method and Kringing interpolation method, a new method for characterizing the flow velocity field of filling mold is proposed. The experimental data show that, on the one hand, the velocity distribution of melt filling process is high in the middle, low in both sides, high in near gate and low in far gate. When ultrasonic vibration is applied, the melt flow velocity increases and the gradient of flow velocity decreases along the flow direction. On the other hand, From the point of view of the size of melt flow velocity and the uniformity of velocity distribution, in injection molding of lmm plastic parts, 800W power ultrasound has the most obvious increase of melt flow velocity in cavity, 600W / 400W / 100W, 200W / 100W, and 200W / 100W respectively. In the injection molding of 3mm 5mm plastic parts, the improvement of the velocity field in the cavity by 200W power ultrasound is the most remarkable, and the velocity field of the cavity is the second by 800W 1OOW.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TQ320.66;TB559

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