【摘要】：本文以生產(chǎn)性能符合要求的微齒輪為目標(biāo)，研究了粒度D10為1.96μm，D50為3.81μm，，D90為9.92μm的羥基鐵粉的粉末注射成形工藝。粘結(jié)劑采用以石蠟為基體的熱塑性粘結(jié)劑體系。其中石蠟和聚乙烯的質(zhì)量分?jǐn)?shù)分別為50%和45%。分別研究了粉末的粒度分布、最佳粉末裝載量、喂料的流動(dòng)性能、脫脂工藝、燒結(jié)工藝、制件力學(xué)性能、微齒輪模流分析及微齒輪模具設(shè)計(jì)。研究表明： 粉末的粒度分布較寬、顆粒細(xì)小，具有很好的成形性能及燒結(jié)性能。粉末的裝載量越高喂料的流動(dòng)性越差，52.54%為喂料的最佳粉末裝載量。最大注射壓力為50Mpa，注射壓力超過(guò)50Mpa時(shí)制件會(huì)產(chǎn)生明顯的飛邊。注射成形件非常均勻，其密度為4.5g/cm3。 在45℃的正庚烷中溶劑脫脂，約第18h時(shí)石蠟已經(jīng)脫除80%以上，連通孔隙已經(jīng)打通。熱脫脂升溫速率快時(shí)坯件會(huì)產(chǎn)生明顯的變形。采用慢速升溫、分段保溫的加熱工藝可得到形狀保持良好、脫脂完全的坯件。最佳升溫工藝為：從室溫到420℃的過(guò)程中平均升溫速率為0.5℃/min,從420℃～650℃的過(guò)程中，平均升溫速率為1℃/min。其中在140℃、250℃、420℃、500℃、650℃分別保溫0.5h、1h、3h、2h、1h。 燒結(jié)溫度在1230℃～1260℃之間所得制件力學(xué)性能最佳。硬度（HRB）平均為67、收縮率平均為18.5%、晶粒直徑為30.87μm。當(dāng)燒結(jié)溫度低于1230℃時(shí)制件孔隙較多，力學(xué)性能較差，。當(dāng)燒結(jié)溫度超過(guò)1260℃時(shí)由于晶粒的明顯長(zhǎng)大，力學(xué)性能也會(huì)明顯下降。 用Moldflow軟件模擬的微齒輪最佳澆口形式為矩形、最低注射壓力為18.7Mpa。注射時(shí)間為1.2s，保壓時(shí)間為10.8s。根據(jù)模擬結(jié)果設(shè)計(jì)出微齒輪成形模具。根據(jù)總結(jié)出的工藝原則上可以生產(chǎn)出性能符合要求的微齒輪。
[Abstract]:In this paper, the powder injection molding process of hydroxyl iron powder with particle size D10 of 1.96 渭 m, D50 of 3.81 渭 m and D90 of 9.92 渭 m has been studied in order to meet the requirements of microgears. The binder adopts thermoplastic binder system based on paraffin wax. The mass fraction of paraffin wax and polyethylene were 50% and 45%, respectively. The particle size distribution of powder, the optimum powder loading, the flow performance of feed, defatting process, sintering process, mechanical properties of parts, microgear die flow analysis and microgear die design were studied respectively. The results show that the particle size distribution of the powder is wide, the particles are fine, and the powder has good formability and sintering properties. The higher the powder loading is, the worse the mobility of the feed is. 52.54% is the best powder loading. The maximum injection pressure is 50 MPA, and when the injection pressure exceeds 50 MPA, the parts will produce obvious flying edges. The injection molding part is very uniform, and its density is 4.5 g / cm ~ 3. At 45 鈩

本文編號(hào)：2501068