【正文】 圖 63 橫澆道橫截面 直澆道總面積為：∑ As＝ ∑ Ag= 6澆冒口系統(tǒng)設(shè)計 機械工程學(xué)院 17 表 11 直澆 道尺寸 D 端面積 As∕ cm2 D∕ mm mmD/1 mml/ 直澆道每厘米長重量∕㎏ 35 40 45 50 43 45 47 48 50 52 53 55 57 58 60 62 400 500 600 400 500 600 400 500 600 400 500 600 已知：直澆道 ∑ As＝ cm2，且鑄件高度的一半為 ,所以選用 D端面積 As＝ cm2的 D＝ 40mm, 1D ＝ 50mm， l ＝ 500mm 類型的直澆道。 出氣孔的分類及尺寸 出氣孔按是否與型外大氣直接相通，分為明出氣孔和暗出氣 孔。拔模斜度為 1:100。s behaviors to care for eyes, basedon the timely and factual statistics the survey series of followup events will also be held in six cities, including Jinan in Shandongprovince, and Changsha in Hunan province, to educate people on how to care for eyes afterthe survey started. More and more Chinese are jogging to get and stay fit. Most joggers will run alone, but some will jog with friends or even coaches. The Beijing Olympic Forest Park is one of the most popular spots. It is packed with runners in the afternoon, usually after work, and at weekends. Jogging after a whole day39。s ovarian function has declined and a bilateral oviduct blockage has occurred, meaning that in vitro fertilization is her only option. So, after reducing her workload, Xiao underwent IVF treatment. Luckily, she got pregnant after just one treatment cycle, but later experienced vaginal bleeding, and rushed to the hospital. I told her to rest and carry on with the treatment (to prevent a miscarriage). As Zubin Zarthoshtimanesh, a yoga guru, demonstrated postures at a high school stadium in Dujiangyan city, Sichuan province, some 200 students sat on colorful mats watching him closely. It was part of the first IndiaChina international yoga festival in the provincial capital, Chengdu, in Southwest China, where more than 1,000 fans from home and abroad gathered for lessons from 20 leading practitioners of the ancient Indian regimen, from June 1721. Yoga is to India what perhaps tai chi is to China. Many countries other than India and China, also held the first World Yoga Day on June 21, after the United Nations last year agreed to Indian Prime Minister Narendra Modi39。s Pink Revolution, an annual campaign that seeks to raise awareness and funds for breast cancer research, the hotel recently announced. A major sponsor of the campaign for three years in a row, Conrad Macao has pledged to donate a portion of its proceeds to the fund, includ ing those collected from selling its popular bear and rubber duck merchandise, in limited pink editions. Pink is the theme for floral arrangements and decorations in the hotel in October. In addition, on Fridays that month, members of the management and staff will add something pink to their uniforms, regular s and handwritten guest cards. Breast cancer is the most prevalent type of cancer among women in Hong Kong and is also of significant concern in Macao and around the world, regardless of age, general manager Bede Barry said in a statement. The hotel has enlisted the support of a number of international and local celebrities to help drive the cause, including South Korean actor Jung Suk Won. This year, a lucky guest who stays at the hotel during the campaign and also donates money for the cause will win a necklace specially designed by Arte Madrid, a Spanish jewelry brand. Women should strive to balance quality of work and life, and have children at a young age. As a doctor I see much suffering because of this imbalance. Xiao Ying, 36, works for a large law firm. Her job means lots of travel, a heavy caseload and a large number of meetings, so her schedule is hectic. She has been pregnant twice, but had abortions on both occasions because she felt her busy, highpressure career wasn39。s annual National Day for Eye Care, the China Youth Development ServiceCenter and Zhejiang Medicine, a leading listed Chinese pharmaceutical pany, jointlyannounced the kickoff of the surve about one month, a questionnaire piled by top eye care medical experts in China willbe distributed through multiple online partners, including , as well asthrough offline survey events held in universities, middle schools and primary schools acrossthe report will be released based on the survey statistics and analysis, and most importantly,guidelines for parents and youth on how to care for the eyes and prevent myopia — agrowing problem in China39。其截面為：10 40mm。 如果沒有明冒口，雖然砂型能透氣，但對金屬液的快速充型，它是無法將型腔內(nèi)的氣體及時排出型外，因此，通常認為出氣孔根部總截面積至少應(yīng)與內(nèi)澆道總截面積相等；對于采用暗出氣孔的砂型，出氣孔根部總截面積至少應(yīng)為內(nèi)澆道總截面積的 倍；以防止型內(nèi)氣壓過分增大。本方案設(shè)有 一 個內(nèi)澆道和兩個陶管內(nèi)徑φ 20（見工藝圖）。 d）內(nèi)澆道應(yīng)有利于平穩(wěn)、快速充型和排氣、排渣，不嚴(yán)重沖刷砂型和砂芯，能盡量縮短金 屬液在型腔中的流程。 內(nèi)澆道：控制金屬液流入型腔的速度和方向，調(diào)節(jié)鑄件各部分的溫差。 澆注系統(tǒng)的組成及其各自作用 常用的澆注系統(tǒng)大多由澆口杯（澆口盆或外澆口）、直澆道、橫澆道、內(nèi)澆道等部分組成。此外，澆注系統(tǒng)的好壞還影響造型和清理工作的繁簡，砂型的體積大小和型砂的耗用運輸量，非生產(chǎn)性消耗的液態(tài)合金用量等等。下箱 間隙 為 1，上箱 間隙 為 2，主要防止合箱時將 砂 子碰 落 ，最后造成缺陷。使用時，芯撐表面應(yīng)無銹、無油、無水、無空氣。 另外，關(guān)于芯撐要求如下： 砂芯在鑄型中主要靠芯頭固定。 其次，分芯的一般原則： a) 砂芯的填砂面應(yīng)寬敞，以便于造芯時填砂，舂砂，安放芯骨，及有利于采取排氣措施。如果這些氣體不能及時排出型外，一旦鉆入金屬液體，就很可能留在里面而使鑄件產(chǎn)生氣孔。5砂芯及砂型設(shè)計 機械工程學(xué)院 11 5 砂芯及砂型設(shè)計 砂芯設(shè)計 砂芯設(shè)計，主要包含芯頭設(shè)計、砂芯排氣設(shè)計等。 表 6 模樣的分型負數(shù) （單位： mm） 砂箱長度 分型負數(shù) a 干 型 表干型 ? 1000 2 1 1001～ 2021 3 2 2021～ 3500 4 3 3501～ 5000 5 4 5000 7 6 —— —— —— 根據(jù)后續(xù)設(shè)計的砂箱長度 2021mm，且型 砂 為自硬型樹脂 砂 ，屬表干型，由表 6查的分型負數(shù)為 2。 冷鐵尺寸 =粗大部位尺寸（ ～ ） 該工藝中導(dǎo)軌為粗大部位，應(yīng)放置冷鐵，根據(jù)導(dǎo)軌尺寸得： 冷鐵尺寸 =44mm (～ )=11～ 17mm 取中間尺寸 15mm，選取 15 40 100mm 規(guī)格的 石墨 冷鐵。由于鑄件的固態(tài)收縮（線收縮）將使鑄件各部分尺寸小于模樣原來的尺寸，因此為了使鑄件冷卻后的尺寸與鑄件圖示一致，則需要在模樣或芯盒上加上其收縮的尺寸。但是，當(dāng)鑄件上的孔、槽的尺寸太小，而鑄件的壁厚又較厚和金屬壓力頭較高時，反而會使鑄件產(chǎn)生粘砂，造成清鏟和機械加工困難；有的孔、槽，為了把它們鑄出，必須采用復(fù)雜而且難度較大的工藝措施，而實現(xiàn)這些措施還不如用機械加工的方法制出更為方便和經(jīng)濟；有時由于孔距要求很精確，鑄出的孔如有偏心，就很難保證加工精度。推薦用于各種鑄造方法和鑄造合金鑄件的 RMA等級列表 3中，它僅供參考。為了避免鑄件澆不足 和冷隔等缺陷，應(yīng)要求鑄件