【正文】 密 度 ~ ~收 縮 率 ~ ~ ~熔 點(diǎn) 130~160 131~165 220~240熱變形溫度（45N/cm178。泛黃原因之一是單體純度不夠，特別是在含有微量元素時(shí)；二是聚合物在空氣中緩慢老化引起發(fā)黃。首先根據(jù)塑件材料及工藝特性用 UG 軟件對(duì)零件進(jìn)行模型分析，然后選擇注塑機(jī)并確定型腔數(shù)目，接著確定成形方案：總體結(jié)構(gòu)設(shè)計(jì)、分型面設(shè)計(jì)、澆注系統(tǒng)設(shè)計(jì)、脫模機(jī)構(gòu)設(shè)計(jì)、冷卻系統(tǒng)設(shè)計(jì)等。ABS 熔體具有明顯的非牛頓性，提高成型壓力可以使熔體粘度明顯減小，粘度隨溫度升高也會(huì)明顯下降。拉伸、壓縮、彎曲強(qiáng)度均相當(dāng)于聚酰胺 聚酰胺 66，沖擊強(qiáng)度高于所有脂肪族聚酰胺和大多數(shù)工程塑料，抗蠕變性也明顯優(yōu)于聚酰胺、聚甲醛。但并非所有ABS制件都要施用高壓，考慮到 8本制件小型、構(gòu)造不算非常復(fù)雜、厚度中等可以用較低的注射壓力。其主要技術(shù)規(guī)格如表 5。根據(jù)以上原則和結(jié)合實(shí)際情況下，本設(shè)計(jì)選用如圖 1 所示分型面： 11圖1 分型面位置 確定型腔的數(shù)量及排列方式該塑件采用一模兩腔成型，型腔布置在模具兩邊呈對(duì)稱狀態(tài)，這樣有利于澆注系統(tǒng)的模具平衡。6）當(dāng)分流道較長(zhǎng)時(shí)，在分流道末端應(yīng)開冷料穴，以容納冷料，保證塑件的質(zhì)量。 型腔徑向尺寸計(jì)算（此題公差為自己標(biāo)注） 16以最大徑向尺寸計(jì)算，測(cè)量得 Ls 為 148mm,塑件精度選為 MT2 對(duì)應(yīng)的型腔加工精度為IT9，以該精度查型腔的尺寸公差表，按照 A 類受模具活動(dòng)部分影響的尺寸公差查表得△=, δ C=△/3=Lm=[148+148（+）/2（3/4）]=149 0+042 型芯外徑尺寸計(jì)算以型芯最大徑向尺寸計(jì)算，測(cè)量得 Ls 為 mm,塑件精度選為 MT2 對(duì)應(yīng)的型腔加工精度為 IT9，以該精度查型腔的尺寸公差表，按照 A 類受模具活動(dòng)部分影響的尺寸公差查表得△=, δ C=△/3=Lm=[+（+）/2+(3/4) ]= 型腔深度尺寸計(jì)算由 測(cè)量得型腔深度為 11mm，以 IT9 精度等級(jí)制造型腔查手冊(cè)，按 B 類不受模具活動(dòng)部分影響的尺寸公差值查表得△=，δ C =Lm=[11+11（+）/2（3/4）] 0+=+ 型芯高度尺寸計(jì)算 測(cè)量得塑件高度尺寸為 ，以 IT9 精度等級(jí)制造查手冊(cè)得，按 A 類不受模具活動(dòng)部分影響的尺寸公差值查表得△=，δ Z=hm=[+(+)/2+(2/3) ] = 17第六章 脫模推出機(jī)構(gòu)的設(shè)計(jì)與模架的選用 脫模推出機(jī)構(gòu)的設(shè)計(jì)制件推出（頂出）是注射成型過程中的最后一個(gè)環(huán)節(jié)，推出質(zhì)量的好壞將最后決定制品的質(zhì)量，因此，制品的推出是不可忽視的。 鎖模力的校核 模具所需的最大鎖模力應(yīng)小于或等于注射機(jī)的額定鎖模力，其關(guān)系按下式校核： P 腔 F≤P 鎖 =150kN式中 P 腔 ——模具的型腔壓力；F——塑件與澆注系統(tǒng)在分型面上的投影面積（mm 2）；P 鎖 ——注射機(jī)的額定鎖模力（N）。 模具的安裝模具的安裝包括預(yù)檢、裝模、緊固、校正頂桿頂出距離，調(diào)節(jié)閉模松緊速和接通冷卻水管或模溫控制系統(tǒng)。大致有三種情況：（1）型心、導(dǎo)柱、推桿彎曲或損壞；（2）型腔局部損壞而大部分讓是好的；（3）使用一段時(shí)間后分型面不嚴(yán)密。感謝老師三年來對(duì)我孜孜不倦的教誨，對(duì)我成長(zhǎng)的關(guān)心和愛護(hù)。t just about sharing art with nomadic families but also about gaining inspiration for the music and dance. Ulan Muqir literally translates as red burgeon, and today39。s villages and entertain nomadic families, but their fame has spread around the world. On May 16 and 17, nearly 100 singers and dancers from the troupe performed at Beijing39。三年的風(fēng)風(fēng)雨雨，我們一同走過，充滿著關(guān)愛，給我留下了值得珍藏的最美好的記憶。在這些情況下，往往不需要將整個(gè)模具報(bào)廢，而是盡量采取修復(fù)。23（2）裝模 模具吊裝時(shí)必須注意安全，盡量整體安裝。P 腔 =kP 成 =1/3140MPa=。1）推出機(jī)構(gòu)應(yīng)盡量設(shè)置在動(dòng)模一側(cè) 由于推出機(jī)構(gòu)的動(dòng)作是通過裝在注射機(jī)合模機(jī)構(gòu)上的頂桿來驅(qū)動(dòng)的，所以一般情況下，推出機(jī)構(gòu)設(shè)在動(dòng)模一側(cè)。否則會(huì)引起反壓力，消耗功能。 圖2這樣的排列方式最大優(yōu)點(diǎn)是便于設(shè)置側(cè)向抽芯機(jī)構(gòu)，進(jìn)料到每個(gè)模腔均勻。 分型面的選擇如何確定分型面，需要考慮的因素比較復(fù)雜。壓力過小，塑料收縮大，與型腔表面脫離接觸的機(jī)會(huì)大，制件表面容易霧化。在工程塑料中，他的耐熱性優(yōu)于聚甲醛、脂肪族聚酰胺和 PBT,與 PET 相當(dāng)，但遜于其他工程塑料。在 80~90℃下干燥 2~3h,可以滿足各種成型要求。由于模具成型具有優(yōu)質(zhì)、高產(chǎn)、省料和成本低等特點(diǎn)，現(xiàn)已在國(guó)民經(jīng)濟(jì)各個(gè)部門，特別是汽車、拖拉機(jī)、航天航空、儀器儀表、機(jī)械制造、家用電器、石油化工、輕工日用品等部門得到極其廣泛的應(yīng)用。 聚苯乙烯（PS）聚苯乙烯是無色無臭的透明剛硬固體，制品擲地時(shí)有金屬般響鳴。④其他性能在干燥的氣候條件下物理力學(xué)性能基本不變，但在潮濕環(huán)境及強(qiáng)烈日照條件下，會(huì)產(chǎn)生表面裂紋并發(fā)暗，在火焰中可緩慢燃燒，離火源后可自熄 [5]。當(dāng)注射速度過快時(shí)，塑料易燒焦或分解析出氣化物，從而在制件上出現(xiàn)熔接痕、光澤差及澆口附近塑料發(fā)紅等缺陷。2）盡量采用簡(jiǎn)單分型面。主流道小端直徑應(yīng)比注射機(jī)噴。否則會(huì)塑件修磨和分割帶來困難。推力點(diǎn)應(yīng)該作用在制品剛性好的部位，如筋部、凸緣、殼體形制品的壁緣處，盡量避免推力點(diǎn)作用在制品的薄平面上，防止制件破裂、穿孔，如殼體形制件及筒形制件多采用推板推出。20所以 F=A+ A 1=10000mm2+=P 模 =103NP 腔 F==103N故 P 腔 F＜P 鎖 即所選注射機(jī)的鎖模力能符合要求。（4）調(diào)整頂桿頂出距離 模具壓穩(wěn)后便慢慢開模，直到動(dòng)模板停止后退，然后調(diào)整頂桿位置。12普通銑床 平口 鉗 鉆頭 游標(biāo)卡尺3 挖槽 曲面粗加工挖槽 CNC 銑床 虎鉗 ￠3 銑刀游標(biāo)卡尺4 挖槽 曲面粗加工挖槽 CNC 銑床 虎鉗 ￠2 球刀游標(biāo)卡尺5 精加工曲面精加工平行銑削CNC 銑床 虎鉗 ￠1 球刀游標(biāo)卡尺6 攻螺紋剛性攻絲 4M8 虎鉗 絲錐9 鉆水路鉆 2248。這是我們就業(yè)前的一次理論與實(shí)踐的熱身訓(xùn)練，也是對(duì)自己在大學(xué)三年中所學(xué)知識(shí)的一次總的檢驗(yàn)。s Liaoning province, decades ago. The solider gave the old man a handmade saddle when they bid farewell. The story inspired Nasun to write Carved Saddle, a song that later became one of his most popular numbers. Now, every year, Nasun recruits young singers and dancers for the troupe. The troupe has also designed a new repertoire, which is mostly based on the daily lives of Mongolian people, especially the lives of nomadic families, and has bined contemporary musical elements with folk songs of the region. Haimu, a 25yearold khoomei (a local variant of overtone singing) singer, joined the troupe three years ago. Along with a sixmember band, he performs fast songs and soft ones that he writes－all while playing the horsehead fiddle.Although I learned the piano since childhood and grew up listening to various kinds of music, to me, the folk music of Inner Mongolia is the root, he says. Performing in remote villages is pleasant. I feel at home on the boundless grasslands, and the warm people there make me feel fulfilled. The first round of spring auction season in Beijing ended last week, but it failed to create much spring in the art market. Although two pieces of Chinese painting fetched more than 100 million yuan, the decline in trading volume and sa le rate showed a downturn this year. In the “Grand View: Chinese Painting Highlight” session at China Guardian 2022 spring auctions, Pan Tianshou’s representative work Eagle, Rock and Flora hit a record auction price of 279 million yuan, while Li Keran’s masterwork Jinggang Mountain fetched million yuan, an unexpected high in recent years. However, the trading volume fells to billion yuan from billion yuan in the same period the year before. The Huangchen 2022 Spring Auctions, which recorded million yuan in total sales, experienced the same. The section number went down to 5 from 12 pared to last year. According to expert Shao Jianwu, the art market did not attract much excitement this year due to the booming stock market and the persistent problems of fery and fake deals. The two pieces of Chinese painting notched up high price this spring due to their own value not due to a revival in the market. The successful transaction of two works with a hammer price of more than 100 million yuan once again confirms that valuable and rare works of high quality always earn the longlasting high price. Chinese painting and calligraphy is still the pillar of the market. However, the overall sales rate has dropped slightly, which reflects the demand for the ordinary auction goods has weakened,” said the president of China Guardian’s Hu Yanyan. Besides, the entry of new buyers also makes certain changes to the direction of purchasing. In a word, the overall market trend is very unpredictable. Although China Guardian 2022 Spring Auctions has achieved remarkable results, it does not me