【正文】
m Cs4=177。 (1)推出機構(gòu)應(yīng) 盡量設(shè)在動模一側(cè)。 (3)機構(gòu)簡單、動作可靠。推桿推出機構(gòu)的特點:推桿加工簡單,更換方便,脫模效果好。圓形結(jié)構(gòu)簡單,應(yīng)用最廣。 6 側(cè)向分型與抽芯機構(gòu)的設(shè)計 當(dāng)注射成型側(cè)壁帶有孔、凹穴、凸臺等塑料制件時 模具上成型該處的零件就必須制成側(cè)向移動的零件,以便 在脫模之前先抽掉側(cè)向成型零件,否則就無法脫模。 滑塊的設(shè)計 滑塊是側(cè)向型芯(小型芯)的安裝和固定的基本或者是部分側(cè)向型腔,在模板和和壓塊構(gòu)成的導(dǎo)滑槽中滑動,要求滑動靈活,感覺無明顯間隙而又不會有卡滯現(xiàn)象。 圖 63 滑塊 滑塊 導(dǎo)滑形式的確定 考慮到綜合機械加工因素,本設(shè)計采用“ T”形導(dǎo)滑塊進行導(dǎo)滑,其結(jié)構(gòu)如圖 64所 19 示。 澆口凝料開模行程 H2,考慮到模具結(jié)構(gòu)及加工,而且塑件加工批量不是很大,本設(shè)計澆口凝料采用手工取出。 根據(jù) 《塑料模具設(shè)計指導(dǎo)(第 2 21 版)》表 73簡化 點澆口模架組合形式(摘自 GB/T125552022) 可確定選用簡化點澆口 JA型, 由于模具形式為瓣合形式,所以 模架中的導(dǎo)柱采用反裝形式, 復(fù)位桿位置也有所改變 。 ( 3)模具的開模行程 S=H1+H2 =15+40 =55mm250mm,校核合格。 ( 3) 澆口 處加強冷卻 塑料熔體 充型時,澆口附近溫度最高,距澆口越遠溫度越低,因此澆口附近應(yīng)加強冷卻,通常將冷卻水道的入口處設(shè)置在澆口附近,使?jié)部诟浇哪>咴谳^低溫度下冷卻,而遠離澆口部分的模具在經(jīng)過一定程度熱交換后溫水作用下冷卻。 24 ( 3) 承受一定的側(cè)向壓力 塑料熔體在充型過程中可能產(chǎn)生單向側(cè)壓力,或者由于成型設(shè)備精度低的影響,使導(dǎo)柱承受了一定的側(cè)向壓力,以保證模具的正常工作。re clear about the terms of the agreement. It might be best to get advice from an experienced adviser, for example, at a Citizens Advice Bureau. To find your nearest CAB, including those that give advice by , click on nearest CAB. For more information about making a claim to an employment tribunal, see Employment tribunals. The (lack of) air up there Cay man Islandsbased Webb, the head of Watch m Fifa39。s plaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day。 Then in high school, think don39。嫌惡過自己的怯懦,最終卻發(fā)現(xiàn)有很多 緣分 ,有很多錯過,好像冥冥之中真的已經(jīng)注定。 Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence. We often close ourselves off when traumatic events happen in our lives。 2. Embrace the unfortable We all know what that twinge of anxiety feels like. We know how fear feels in our bodies: the tension in our necks, the tightness in our stomachs, etc. We can practice leaning into these feelings of disfort and let them show us where we need to go.我們都經(jīng)歷過焦灼的煎熬感,也都感受過恐懼造成的生理反應(yīng):脖子僵硬、胃酸翻騰。s not needed. Instead, he plans to deploy his 270squarefoot (25squaremeter) main chute at an altitude of around 5,000 feet (1,524 meters). In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds. Even if everything goes as planned, it won39。 3. Ask your heart what it wants 傾聽內(nèi)心 We’re often confused at the next step to take, making pros and cons lists until our eyes bleed and our brains are sore. Instead of always taking this approach, what if we engaged a new part of ourselves that isn’t usually involved in the decision making process?我們常對未來猶疑不定,反復(fù)考慮利弊直到身心俱疲。下面六個方法有助于你更完滿透徹地敞開心扉。 From the corner at the beginning of deep friendship。 A person39。二十年的人生軌跡深深淺淺,突然就感覺 到有些事情,非做不可了。s about how he felt and I would like to speak to him first to find out what his experience was. Uefa has opened disciplinary proceedings against CSKA for the racist behaviour of their fans during City39。 11 模具工作過程 模具裝配試模完畢之后(見總裝圖),模具進入正式工作狀態(tài),模具基本工作過程如下 : ( 1) 對塑料進行烘干,并裝入料斗; ( 2) 清理模具,并進行適當(dāng)?shù)念A(yù)熱; ( 3) 合模、鎖緊模具; ( 4) 對塑料進行預(yù)塑化,注射裝置準備注射; ( 5) 注射,其過程包括充模、保壓、倒流、澆口凍結(jié)后的冷卻和脫模; ( 6) 脫模過程: 當(dāng)注射機開模時, 中間板先與定模板分離,脫 ag an employment tribunal clai Emloyment tribunals sort out disagreements between employers and employees. You may need to make a claim to an employment tribunal if: you don39。 本塑件為小型制件, 厚度較小,同時由于模具結(jié)構(gòu),故本設(shè)計冷卻水道只在中間板上開設(shè)兩個,如圖 91 所示。注射模具中設(shè)置溫度調(diào)節(jié)系統(tǒng)的目的,就是要 通過控制模具溫度,使注射成型具有良好的產(chǎn)品質(zhì)量和較高的生產(chǎn)效率。 經(jīng)上述尺寸確定,模架尺寸已 改裝后的模架形式如圖 71所示。 ( 2) 楔緊塊 的楔角:模具在合模時,為了使滑塊能 夠復(fù)位, 鎖緊,其 楔角 應(yīng)等于滑塊楔角,為 30176。 本設(shè)計的抽芯距如圖66所示。左右。 根據(jù)動力來源的不同,側(cè)向分型與抽芯機構(gòu)一般可分為機動、液壓(液動)或氣動以及手動等三大類。由于滑輪軸肩高度很小,且塑件冷卻后會收縮,因此脫模力極小,推桿足夠推出塑件 。為了避免細長桿變形,對于直徑為 以下的推桿最好設(shè)計成階梯形。 (5)合模時的正確復(fù)位。為了保證塑件在推出過程最后不變形、 不 損壞 ,設(shè)計時應(yīng)仔細分析塑件對模具包緊力和黏附力的大小,合理的選擇推出方式和推出位置。 型腔側(cè)壁厚度計算公式為 : S=r ? ?? ? ???????? ?? 12 P? ? (式 43) 式中 S —— 型腔側(cè)壁厚度( mm) r —— 型腔內(nèi)半徑 ( mm) ,在此取最大半徑 r= ??? —— 材料許用應(yīng)力 ( MPa) , ??? = s? /ns( s? 為材料屈服點, 40Cr 的屈服點為s? =784MPa, ns為 安全系數(shù),通常取 ~ ,在此取 ,得 ? ?? = s? /ns=784/2=392MPa P —— 型腔內(nèi)塑料熔體 壓力( MPa) , 查《塑料模具設(shè)計指導(dǎo)(第 2 版)》表 22常用塑料注射成型時型腔平均壓力 ,取 P=25( MPa) 將各數(shù)據(jù)代入公式求得 S=,本設(shè)計最小側(cè)壁厚度 S=5mm,滿足要求。 =? mm, 相應(yīng)塑件制造公差△ 3= 計算公式為 : (LM)0 +δ z=[(1+Scp)lsx△ ] (式 41) 式中是塑件平均收縮率,塑件平均收縮率為 1%~ %,所以其平均收縮率 Scp=( +) /2=(下同) ; X是系數(shù),查《塑料模具設(shè)計指導(dǎo)(第 2版)》表 210,取 X1=, 2=, X3=;△是塑件相應(yīng)尺寸的公差;δ z是塑件上相應(yīng)尺寸制造公差,查《塑料模具設(shè)計指導(dǎo)(第 2 版)》表 211,取δ z1=, δ z2=, δz3=。根據(jù)對成型塑件的綜合分析,該塑件的成型零件要有足夠的剛度、強度、耐磨性及良好的抗疲勞性。 本次設(shè)計采用點 澆口形式。 ( 6)避免產(chǎn)生噴射和蠕動(蛇形流) 塑料熔體的流動主要受塑件的形狀和尺寸以及澆口的位置和尺寸的支配,良好的流動將保證模具型腔的均勻充填并防止分層。熔接痕降低塑件的強度,并 有損于外