- 學位論文
應用模內感測器結合PvT監控 金屬粉末射出成型在初胚時收縮差異之研究
Research on Monitoring the Shrinkage Difference of Metal Powder Injection Molding in the Embryo by Using In-mold Sensor Combined with PvT
摘要
塑膠成型這項工藝已存在許久，而其中金屬粉末射出成型(Metal Injection Molding 簡稱MIM)有別於傳統射出成型，是將金屬粉末與塑膠進行混鍊再造粒，而產出我們所看到的原料粒，且在射出完成後，還需要經過多道複雜工序如脫脂、燒結……等等，最終才會取得我們所需的產品。此項工藝雖然看似複雜，卻也存在極大的價值，例如:可以生產出結構較複雜或較細微的產品、且於模具及射出機許可下，亦可短時間內生產較多的產品、並將初坯不良品重複回收、重新造粒以節省原料成本，上述種種優點賦予了金屬粉末射出成型存在的意義。 過往對於MIM的研究主要著眼於脫脂及燒結，且初胚的成型品質往往決定了後續的製程和對應的最終品質。由於熔膠在模具內部的狀態無法可視化觀察，故難以判定生產出來初胚品質是否穩定。本研究使用模穴壓力和溫度感測器，藉著監控壓力和溫度的變化搭配PvT(Pressure-Specific Volume-Temperature)的關係來判定成型參數對初胚收縮率的影響，以達到改善初胚品質的目標。研究採用平板型試片，量測前後段收縮率並和PvT預測的比容值比較。 研究結果顯示，透過PvT搭配模內的溫度以及壓力感測器可以有效的監測產品在成型時降溫至頂出前的比容值變化，同時也驗證了將這項技術可以被應用在監測MIM初胚的收縮率，在試品兩段的收縮差異以及比容值差異之間的相關度高達0.95以上，呈現出高度的關聯性。研究結果也發現使用模穴壓力和溫度感測器，藉著監控壓力和溫度的變化搭配PvT(Pressure-Specific Volume-Temperature)的關係對於MIM製程可視化能提供有利的協助。
並列摘要
The technology of plastic forming has been used widely for a long time. Thereof, Metal Injection Molding (MIM), mixing metal powder with plastic and then granulating to produce the raw materials is different from the traditional injection molding. Besides, after injection, it still has to be in the multiple complex process of degreasing, sintering, etc. Although the procedures might seem complicated, this technology also can create the great value. For instance, producing products with complex or fine structures, producing in a short period of time with the feasibility of the injection machine, generating less waste, repeatedly recycling the defective initial products and re granulating to save the material costs. All these advantages give the significance of metal powder injection molding. The research of MIM was mainly focused on degreasing and sintering in the past and the subsequent process and corresponding final quality often depends on the molding quality of the embryo. We’re hard to tell whether the quality of the produced product was stable because it is incapable to visually observe the state of the molten adhesive inside the mold. Therefore, we select to use the cavity pressure and temperature sensors to conduct research. In order to achieve the goal of improving the quality of embryos, we monitor the changes in pressure and temperature in conjunction with PvT (Pressure Specific Volume Temperature) to determine the impact of molding parameters on the shrinkage rate of the embryo. The research used flat-plate test pieces to measure the shrinkage rate of the front and rear segments and compared it with the predicted specific volume value of PvT. The research results suggested that combining PvT with temperature and pressure sensors which is inside the mold can monitor effectively the specific volume changes of the product from cooling down to ejecting during molding. Meanwhile, it also verified that this technology can be applied to monitor the shrinkage results of the MIM initial embryo, and the correlation between the shrinkage differences and specific volume differences between the two stages of the product is up to 0.95, indicating a highly positive correlation. The research results even found that using the cavity pressure and temperature sensors and monitoring the changes in pressure and temperature in conjunction with PvT can provide favorable assistance for MIM process visualization.