腳踏鑄造工藝設(shè)計(jì)

1、腳踏鑄造工藝設(shè)計(jì)初選鑄件形狀為自行車腳踏板1 腳踏的鑄造工藝1.1腳踏的材質(zhì)腳踏的材質(zhì)為HT150鑄造HT150這種材質(zhì)的鑄造性能較好，熔點(diǎn)較低，實(shí)際流動(dòng)性較好，易氧化，鑄造縮水率約0.8%1.0%，凝固收縮約1%，澆注溫度約14001450。1.2腳踏的結(jié)構(gòu)特點(diǎn)及技術(shù)要求1.3鑄造方法的選擇 該零件結(jié)構(gòu)簡(jiǎn)單，選用砂型鑄造。砂型鑄造的優(yōu)勢(shì)有： （1）砂型鑄造成本低； （2）砂型鑄造生產(chǎn)靈活，既適用于單件小批量生產(chǎn)，又適用于大批量生產(chǎn)； （3）砂型鑄造可以用于生產(chǎn)大型鑄件。 選用濕型，濕型比較簡(jiǎn)單，經(jīng)濟(jì)。1.3.1型砂、芯砂類型的選擇選用自硬樹(shù)脂砂造芯。自硬樹(shù)脂砂的優(yōu)勢(shì)有：（1）樹(shù)脂砂與粘土砂相

2、比鑄件尺寸精度高，表面粗糙度低，可以顯著減低鑄件廢品率；（2）自硬樹(shù)脂砂能常溫自硬成型，節(jié)能節(jié)材；（3）芯砂在可使用時(shí)間內(nèi)流動(dòng)性好，能在較小緊實(shí)力的作用下，較好地充填形狀復(fù)雜的型、芯各個(gè)部位，減輕工人的勞動(dòng)強(qiáng)度；（4）芯砂的潰散性好，鑄件落砂、清理容易。1.3 .2造型、制芯方法的選擇（1）選用手工造型此零件采用兩箱手工造型，造型時(shí)先將上砂型舂好，然后翻箱，舂實(shí)下砂型。這種工藝適用范圍廣，操作簡(jiǎn)便，不需要復(fù)雜的設(shè)備、生產(chǎn)靈活，因而適合于各種生產(chǎn)批量的鑄件。（2）選用熱芯盒制芯 采用應(yīng)用廣泛的熱芯盒制芯方法，該制芯方法是通過(guò)機(jī)器吹砂的方式在芯盒中形成一定壁厚的砂芯，制芯過(guò)程機(jī)械化，生產(chǎn)效率高，可

3、以降低工人的勞動(dòng)強(qiáng)度，制芯周期短，砂芯質(zhì)量好，可以保證鑄件的成形質(zhì)量。2.鑄造工藝方案設(shè)計(jì)2.1澆注位置的確定鑄件的澆注位置是指澆注時(shí)鑄件在鑄型中所處的位置，澆注位置是根據(jù)鑄件的結(jié)構(gòu)特點(diǎn)、尺寸、重量、技術(shù)要求、鑄造合金特性、鑄造方法以及生產(chǎn)條件決定的。正確的澆注位置應(yīng)能保證獲得健全的鑄件結(jié)構(gòu)，同時(shí)使得造型、下芯、清理方便。同時(shí)，確定澆注位置在很大程度上著眼于控制鑄件的凝固。確定澆注位置的基本原則如下：（1）澆注位置應(yīng)有利于所確定的凝固順序，鑄件厚實(shí)部位一般應(yīng)置于澆注位置上方，以利于設(shè)置冒口補(bǔ)縮；（2）鑄件的重要部位應(yīng)盡量置于下部；（3）重要加工面應(yīng)朝下或呈直立狀態(tài)，朝下的表面或側(cè)立表面通常比較

4、光潔，出現(xiàn)缺陷的可能性??；（4）鑄件的大平面朝下或者成側(cè)立面，避免夾砂、結(jié)疤缺陷；（5）對(duì)具有薄壁部分的鑄件，應(yīng)把薄壁部分放在內(nèi)澆道以下或置于鑄型的下部，以免出現(xiàn)澆不足、冷隔等缺陷；（6）便于下芯、合型及檢驗(yàn)；（7）應(yīng)使合型位置、澆注位置和鑄件冷卻位置相一致。鑄件采用水平擺放，有利于降低澆注系統(tǒng)和冒口的設(shè)置難度，并且方便下芯，同時(shí)也有利于鑄件的順序凝固，所以本設(shè)計(jì)采用鑄件水平擺放的澆注方案。 鑄件的澆注位置及分型面2.2分型面的確定分型面是指兩半鑄型相互接觸的表面。合理的選擇分型面，對(duì)于簡(jiǎn)化鑄造工藝、生產(chǎn)效率等有著直接關(guān)聯(lián)，并且能夠提高鑄件良品率。分型面的選擇應(yīng)盡量與澆注位置一致，應(yīng)選擇平面，

5、使得鑄造工藝簡(jiǎn)便，保證鑄件質(zhì)量，且盡可能減少鑄件的分型面數(shù)目。本設(shè)計(jì)選擇的分型面如上圖所示，其優(yōu)點(diǎn)有：（1）下芯較為容易，降低工人勞動(dòng)強(qiáng)度；（2）鑄件最大截面在分型面上，造型、下芯方便；（3）澆注系統(tǒng)和冒口的設(shè)置較為方便；（4）分型面與澆注位置一致，方便澆注系統(tǒng)的設(shè)計(jì)。2.3鑄件機(jī)械加工初基準(zhǔn)的選擇鑄件在機(jī)械加工時(shí)，作為首次裝夾、定位用的基準(zhǔn)面稱為機(jī)加工初基準(zhǔn)面。如果鑄件機(jī)加工基準(zhǔn)選擇不當(dāng)或初基準(zhǔn)本身尺寸精度低，表面不平整，將使鑄件裝夾、定位困難。選擇初基準(zhǔn)時(shí)應(yīng)注意以下問(wèn)題：（1）應(yīng)盡量選擇鑄件非加工面為初基準(zhǔn)面；（2）應(yīng)選擇加工余量最小或尺寸公差最小的表面為初基準(zhǔn)面；（3）應(yīng)選擇鑄件尺寸最穩(wěn)

6、定的表面為加工初基準(zhǔn)面，盡量選擇由砂型成形的表面；（4）盡可能在一次裝夾中加工出多個(gè)表面。由零件圖中部分表面有粗糙度的要求來(lái)判定該面需要機(jī)械加工，從整體上看我們可以選擇下圖中紅色所指的平面作為鑄件的機(jī)加工基準(zhǔn)面。3 鑄造工藝設(shè)計(jì)3.5 起模斜度 當(dāng)鑄件沒(méi)有結(jié)構(gòu)斜度時(shí)，為了保證鑄件的順利起模，有必要在鑄件上設(shè)置起模斜度，以免損壞砂型或砂芯。起模斜度可采取增加鑄件壁厚、增減鑄件壁厚或減少鑄件壁厚的方式來(lái)形成。在鑄件上加起模斜度，原則上不應(yīng)超出鑄件的壁厚公差要求，并且同一鑄件上，上、下兩個(gè)模樣的起模斜度應(yīng)取在分型面上的同一點(diǎn)。本設(shè)計(jì)采用增加鑄件壁厚的方法來(lái)設(shè)置起模斜度。 本次設(shè)計(jì)選用的是鋁合金制模樣

7、，查鑄造手冊(cè) 第5卷 鑄造工藝（第2版）表3-70，得該鑄件外表面的起模斜度為 內(nèi)表面的起模斜度為起模斜度取法示意圖 增加鑄件壁厚的示意圖4 砂芯設(shè)計(jì) 砂芯的功用是形成鑄件的內(nèi)腔、孔和鑄件外形不能出砂的部位。砂型局部要求特殊性能的部分，有時(shí)也用砂芯.4.1砂芯的設(shè)置 砂型應(yīng)滿足的要求：砂芯的形狀、尺寸以及在砂型中的位置應(yīng)符合鑄件要求，具有足夠的強(qiáng)度和剛度，在鑄件形成過(guò)程中砂芯所產(chǎn)生的氣體能及時(shí)排出型外，鑄件收縮時(shí)阻力小且容易清砂。砂芯設(shè)置的基本原則有：（1）為了減少制造工時(shí)，降低鑄件成本和提高其尺寸精度，對(duì)于不太復(fù)雜的鑄件，應(yīng)盡量減少砂芯數(shù)量；（2）復(fù)雜的大砂芯、細(xì)而很長(zhǎng)的砂芯可分為幾個(gè)小而簡(jiǎn)

8、單的砂芯；（3）保證鑄件內(nèi)腔尺寸精度以及鑄件壁厚均勻；（4）填砂面應(yīng)寬敞，烘干支撐面是平面；（5）砂芯形狀適應(yīng)造型、制芯方法。 除了上述原則外，還應(yīng)使每塊砂芯有足夠的斷面，保證有一定的強(qiáng)度和剛度，并能順利排出砂芯中的氣體；使芯盒結(jié)構(gòu)簡(jiǎn)單，便于制造和使用。本體零件中部圓桶采用整體砂芯水平放放置 4.2 砂芯的校核計(jì)算1）砂芯所受的重力：G=mg=2）砂芯所受的浮力：F=gv=3）計(jì)算下芯頭所受的最大壓力：下芯頭所受的壓力等于重力：P=G=4）計(jì)算芯頭所需的承壓面積：下芯頭的面積為：S下=R2=S下A下所以1#砂芯的芯頭尺寸合格。5.澆注系統(tǒng)的設(shè)計(jì)5.1澆注系統(tǒng)的選擇鑄件材料為ZG-230,選用開(kāi)

9、放式澆注系統(tǒng)。按內(nèi)澆道在鑄件上的位置澆注系統(tǒng)可分為：頂注式、底注式、中間注入式和階梯式澆注系統(tǒng)。其中中間注入式澆注系統(tǒng)適用于壁厚較均勻、高度不太大的中小型鑄件，此次零件壁厚較均勻，為便于分型和拔模，故選用中間注入式澆注系統(tǒng)。5.2 澆注系統(tǒng)引入位置的確定澆注系統(tǒng)的引入位置影響到澆注系統(tǒng)結(jié)構(gòu)類型的確定，同時(shí)對(duì)液態(tài)金屬的充型方式、鑄型溫度分布、鑄件質(zhì)量影響很大，因此在澆注系統(tǒng)設(shè)計(jì)中，對(duì)于內(nèi)澆道的引入位置，要給予充分考慮。對(duì)于結(jié)構(gòu)相對(duì)復(fù)雜的中型鑄鋼件,其進(jìn)液方式以中注優(yōu)先,原則是盡可能地簡(jiǎn)化澆注系統(tǒng)及造型工藝。5.3 澆注系統(tǒng)結(jié)構(gòu)尺寸的確定5.3.1澆注系統(tǒng)最小斷面積計(jì)算：根據(jù)截面比設(shè)計(jì)法，內(nèi)澆道截

10、面面積計(jì)算公式為： (5-1)式中：Amin直澆道截面積； G金屬液總重量；澆注時(shí)間；金屬液密度；流量損耗系數(shù)； Hp平均靜壓頭高度；G=2900kg,t=40s, =0.33,Hp=84.3775cm即該鑄件澆注系統(tǒng)中最小的橫截面積為 cm2。我們?nèi)?cm2 。則A內(nèi)= cm2 A橫= cm2 A直= cm2 5.3.2 澆注系統(tǒng)各截面尺寸和形狀的確定直澆道形狀和尺寸的確定采用圓錐形直澆道，根據(jù)計(jì)算得出的結(jié)果，當(dāng)采用一個(gè)直澆道時(shí)，直澆道的半徑0 cm所以其直徑D= mm。l= mm,D1= mm直澆道尺寸圖橫澆道形狀和尺寸的確定橫澆道的總橫截面積為 m2， 如下圖所示，橫澆道的尺寸為：a=

11、mm；b= mm；R= mm。橫澆道的尺寸內(nèi)澆道形狀和尺寸的確定內(nèi)澆道的總橫截面積為 m2 有 6個(gè)內(nèi)澆道，故a= mm；b= mm；c= mm.6.冒口設(shè)計(jì) 冒口位置的選擇有以下五種：（1）冒口應(yīng)就近設(shè)在鑄件熱節(jié)的上方或側(cè)旁；（2）冒口應(yīng)盡量設(shè)在鑄件最高、最厚的部位。對(duì)低處的熱節(jié)增設(shè)補(bǔ)貼或使用冷鐵造成補(bǔ)縮的有利條件；（3）冒口不應(yīng)設(shè)在鑄件重要的、受力大的部位，以防止該處組織粗大從而降低鑄件的強(qiáng)度；（4）冒口位置不要選在鑄造應(yīng)力集中處，應(yīng)注意減輕對(duì)鑄件的收縮阻礙，以防引起裂紋；（5）盡量用一個(gè)冒口同時(shí)補(bǔ)縮幾個(gè)熱節(jié)或鑄件部位。 根據(jù)以上原則，我們把冒口設(shè)置在鑄件大平板頂處，由于鑄件高度不高，采用

12、明冒口中的頂冒口，圓錐形，由鑄件頂面向上擴(kuò)大8，冒口尺寸有:冒口根部直徑D=(1.22)d , 冒口高度HD 為了保證冒口中的金屬液可以滿足鑄件需要補(bǔ)縮部位的金屬液量，我們需要驗(yàn)證冒口中的金屬液量是否大于鑄件某部位需要補(bǔ)縮的液量。因此，設(shè)計(jì)中采用補(bǔ)縮液量法對(duì)該鑄件明冒口進(jìn)行校核，冒口中需儲(chǔ)存的補(bǔ)縮液量按下式計(jì)算：G0=1.6Gc 式中：G0-冒口中需儲(chǔ)存的補(bǔ)縮液量；Gc-冒口補(bǔ)縮區(qū)內(nèi)對(duì)應(yīng)于原型腔體積和澆注后型腔擴(kuò)大體積之和的鑄件重量； -金屬液的體收縮率機(jī)械設(shè)計(jì)理論機(jī)械設(shè)計(jì)是一門(mén)通過(guò)設(shè)計(jì)新產(chǎn)品或者改進(jìn)老產(chǎn)品來(lái)滿足人類需求的應(yīng)用技術(shù)科學(xué)。它涉及工程技術(shù)的各個(gè)領(lǐng)域，主要研究產(chǎn)品的尺寸、形狀和詳細(xì)結(jié)

13、構(gòu)的基本構(gòu)思，還要研究產(chǎn)品在制造、銷售和使用等方面的問(wèn)題。進(jìn)行各種機(jī)械設(shè)計(jì)工作的人員通常被稱為設(shè)計(jì)人員或者機(jī)械設(shè)計(jì)工程師。機(jī)械設(shè)計(jì)是一項(xiàng)創(chuàng)造性的工作。設(shè)計(jì)工程師不僅在工作上要有創(chuàng)造性，還必須在機(jī)械制圖、運(yùn)動(dòng)學(xué)、工程材料、材料力學(xué)和機(jī)械制造工藝學(xué)等方面具有深厚的基礎(chǔ)知識(shí)。 如前所訴，機(jī)械設(shè)計(jì)的目的是生產(chǎn)能夠滿足人類需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科技知識(shí)本身并不一定能給人類帶來(lái)好處，只有當(dāng)它們被應(yīng)用在產(chǎn)品上才能產(chǎn)生效益。因而，應(yīng)該認(rèn)識(shí)到在一個(gè)特定的產(chǎn)品進(jìn)行設(shè)計(jì)之前，必須先確定人們是否需要這種產(chǎn)品。應(yīng)當(dāng)把機(jī)械設(shè)計(jì)看成是機(jī)械設(shè)計(jì)人員運(yùn)用創(chuàng)造性的才能進(jìn)行產(chǎn)品設(shè)計(jì)、系統(tǒng)分析和制定產(chǎn)品的制造工藝學(xué)的一個(gè)良機(jī)。掌握

14、工程基礎(chǔ)知識(shí)要比熟記一些數(shù)據(jù)和公式更為重要。僅僅使用數(shù)據(jù)和公式是不足以在一個(gè)好的設(shè)計(jì)中做出所需的全部決定的。另一方面，應(yīng)該認(rèn)真精確的進(jìn)行所有運(yùn)算。例如，即使將一個(gè)小數(shù)點(diǎn)的位置放錯(cuò)，也會(huì)使正確的設(shè)計(jì)變成錯(cuò)誤的。一個(gè)好的設(shè)計(jì)人員應(yīng)該勇于提出新的想法，而且愿意承擔(dān)一定的風(fēng)險(xiǎn)，當(dāng)新的方法不適用時(shí)，就使用原來(lái)的方法。因此，設(shè)計(jì)人員必須要有耐心，因?yàn)?所花費(fèi)的時(shí)間和努力并不能保證帶來(lái)成功。一個(gè)全新的設(shè)計(jì)，要求屏棄許多陳舊的，為人們所熟知的方法。由于許多人墨守成規(guī)，這樣做并不是一件容易的事。一位機(jī)械設(shè)計(jì)師應(yīng)該不斷地探索改進(jìn)現(xiàn)有的產(chǎn)品的方法，在此過(guò)程中應(yīng)該認(rèn)真選擇原有的、經(jīng)過(guò)驗(yàn)證的設(shè)計(jì)原理，將其與未經(jīng)過(guò)驗(yàn)證的

15、新觀念結(jié)合起來(lái)。新設(shè)計(jì)本身會(huì)有許多缺陷和未能預(yù)料的問(wèn)題發(fā)生，只有當(dāng)這些缺陷和問(wèn)題被解決之后，才能體現(xiàn)出新產(chǎn)品的優(yōu)越性。因此，一個(gè)性能優(yōu)越的產(chǎn)品誕生的同時(shí)，也伴隨著較高的風(fēng)險(xiǎn)。應(yīng)該強(qiáng)調(diào)的是，如果設(shè)計(jì)本身不要求采用全新的方法，就沒(méi)有必要僅僅為了變革的目的而采用新方法。在設(shè)計(jì)的初始階段，應(yīng)該允許設(shè)計(jì)人員充分發(fā)揮創(chuàng)造性，不受各種約束。即使產(chǎn)生了許多不切實(shí)際的想法，也會(huì)在設(shè)計(jì)的早期，即繪制圖紙之前被改正掉。只有這樣，才不致于堵塞創(chuàng)新的思路。通常，要提出幾套設(shè)計(jì)方案，然后加以比較。很有可能在最后選定的方案中，采用了某些未被接受的方案中的一些想法。 心理學(xué)家經(jīng)常談?wù)撊绾问谷藗冞m應(yīng)他們所操作的機(jī)器。設(shè)計(jì)人員的

16、基本職責(zé)是努力使機(jī)器來(lái)適應(yīng)人們。這并不是一項(xiàng)容易的工作，因?yàn)閷?shí)際上并不存在著一個(gè)對(duì)所有人來(lái)說(shuō)都是最優(yōu)的操作范圍和操作過(guò)程。另一個(gè)重要問(wèn)題，設(shè)計(jì)工程師必須能夠同其他有關(guān)人員進(jìn)行交流和磋商。在開(kāi)始階段，設(shè)計(jì)人員必須就初步設(shè)計(jì)同管理人員進(jìn)行交流和磋商，并得到批準(zhǔn)。這一般是通過(guò)口頭討論，草圖和文字材料進(jìn)行的。為了進(jìn)行有效的交流 ，需要解決下列問(wèn)題：（1） 所設(shè)計(jì)的這個(gè)產(chǎn)品是否真正為人們所需要？（2） 此產(chǎn)品與其他公司的現(xiàn)有同類產(chǎn)品相比有無(wú)競(jìng)爭(zhēng)能力？（3） 生產(chǎn)這種產(chǎn)品是否經(jīng)濟(jì)？（4） 產(chǎn)品的維修是否方便？（5） 產(chǎn)品有無(wú)銷路？是否可以盈利？ 只有時(shí)間能對(duì)上述問(wèn)題給出正確答案。但是， 產(chǎn)品的設(shè)計(jì)、制造和

17、銷售只能在對(duì)上述問(wèn)題的初步肯定答案的基礎(chǔ)上進(jìn)行。設(shè)計(jì)工程師還應(yīng)該通過(guò)零件圖和裝配圖，與制造部門(mén)一起對(duì)最終設(shè)計(jì)方案進(jìn)行磋商。通常 ，在制造過(guò)程中會(huì)出現(xiàn)某個(gè)問(wèn)題?？赡軙?huì)要求對(duì)某個(gè)零件尺寸或公差作一些更改，使零件的生產(chǎn)變得容易。但是，工程上的更改必須要經(jīng)過(guò)設(shè)計(jì)人員批準(zhǔn)，以保證不會(huì)損傷產(chǎn)品的功能。有時(shí)，在產(chǎn)品的裝配時(shí)或者裝箱外運(yùn)前的試驗(yàn)中才發(fā)現(xiàn)設(shè)計(jì)中的某種缺陷。這些事例恰好說(shuō)明了設(shè)計(jì)是一個(gè)動(dòng)態(tài)過(guò)程。總是存在著更好的方法來(lái)完成設(shè)計(jì)工作，設(shè)計(jì)人員應(yīng)該不斷努力，尋找這些更好的方法。近些年來(lái)，工程材料的選擇已經(jīng)顯得重要。此外，選擇過(guò)程應(yīng)該是一個(gè)對(duì)材料的連續(xù)不斷的重新評(píng)價(jià)過(guò)程。新材料不斷出現(xiàn)，而一些原有的材料的

18、能夠獲得的數(shù)量可能會(huì)減少。環(huán)境污染、材料的回收利用、工人的健康及安全等方面經(jīng)常會(huì)對(duì)材料選擇附加新的限制條件。為了減輕重量或者節(jié)約能源，可能會(huì)要求使用不同的材料。來(lái)自國(guó)內(nèi)和國(guó)際競(jìng)爭(zhēng)、對(duì)產(chǎn)品維修保養(yǎng)方便性要求的提高和顧客的反饋等方面的壓力，都會(huì)促使人們對(duì)材料進(jìn)行重新評(píng)價(jià)。由于材料選用不當(dāng)造成的產(chǎn)品責(zé)任訴訟，已經(jīng)產(chǎn)生了深刻的影響。此外，材料與材料加工之間的相互依賴關(guān)系已經(jīng)被人們認(rèn)識(shí)得更清楚。因此，為了能在合理的成本和確保質(zhì)量的前提下獲得滿意的結(jié)果，設(shè)計(jì)工程師的制造工程師都必須認(rèn)真仔細(xì)地選擇、確定和使用材料。制造任何產(chǎn)品的第一步工作都是設(shè)計(jì)。設(shè)計(jì)通?？梢苑譃閹讉€(gè)明確的階段：（a）初步設(shè)計(jì)；（b）功能設(shè)

19、計(jì)；（c）生產(chǎn)設(shè)計(jì)。在初步設(shè)計(jì)階段，設(shè)計(jì)者著重考慮產(chǎn)品應(yīng)該具有的功能。通常要設(shè)想和考慮幾個(gè)方案，然后決定這種思想是否可行；如果可行，則應(yīng)該對(duì)其中一個(gè)或幾個(gè)方案作進(jìn)一步的改進(jìn)。在此階段，關(guān)于材料選擇唯一要考慮的問(wèn)題是：是否有性能符合要求的材料可供選擇；如果沒(méi)有的話，是否有較大的把握在成本和時(shí)間都允許的限度內(nèi)研制出一種新材料。在功能設(shè)計(jì)和工程設(shè)計(jì)階段，要做出一個(gè)切實(shí)可行的設(shè)計(jì)。在這個(gè)階段要繪制出相當(dāng)完整的圖紙，選擇并確定各種零件的材料。通常要制造出樣機(jī)或者實(shí)物模型，并對(duì)其進(jìn)行試驗(yàn)，評(píng)價(jià)產(chǎn)品的功能、可靠性、外觀和維修保養(yǎng)性等。雖然這種試驗(yàn)可能會(huì)表明，在產(chǎn)品進(jìn)入到生產(chǎn)階段之前，應(yīng)該更換某些材料，但是，

20、絕對(duì)不能將這一點(diǎn)作為不認(rèn)真選擇材料的借口。應(yīng)該結(jié)合產(chǎn)品的功能，認(rèn)真仔細(xì)地考慮產(chǎn)品的外觀、成本和可靠性。一個(gè)很有成就的公司在制造所有的樣機(jī)時(shí)，所選用的材料應(yīng)該和其生產(chǎn)中使用的材料相同，并盡可能使用同樣的制造技術(shù)。這樣對(duì)公司是很有好處的。功能完備的樣機(jī)如果不能根據(jù)預(yù)期的銷售量經(jīng)濟(jì)地制造出來(lái)，或者是樣機(jī)與正式生產(chǎn)的裝置在質(zhì)量和可靠性方面有很大不同，則這種樣機(jī)就沒(méi)有多大的價(jià)值。設(shè)計(jì)工程師最好能在這一階段完全完成材料的分析、選擇和確定工作，而不是將其留到生產(chǎn)設(shè)計(jì)階段去做。因?yàn)?，在生產(chǎn)設(shè)計(jì)階段材料的更換是由其他人進(jìn)行的，這些人對(duì)產(chǎn)品的所有功能的了解不如設(shè)計(jì)工程師。 在生產(chǎn)設(shè)計(jì)階段中，與材料有關(guān)的主要問(wèn)題是

21、應(yīng)該把材料完全確定下來(lái)，使它們與現(xiàn)有的設(shè)備相適應(yīng)，能夠利用現(xiàn)有設(shè)備經(jīng)濟(jì)地進(jìn)行加工，而且材料的數(shù)量能夠比較容易保證供應(yīng)。在制造過(guò)程中，不可避免地會(huì)出現(xiàn)對(duì)使用中的材料做一些更改的情況。經(jīng)驗(yàn)表明，可采用某些便宜材料作為替代品。然而，在大多數(shù)情況下，在進(jìn)行生產(chǎn)以后改換材料要比在開(kāi)始生產(chǎn)前改換材料所花費(fèi)的代價(jià)要高。在設(shè)計(jì)階段做好材料選擇工作，可以避免多數(shù)這樣的情況。在生產(chǎn)制造開(kāi)始后出現(xiàn)了可供使用的新材料是更換材料的最常見(jiàn)的原因。當(dāng)然，這些新材料可能降低成本、改進(jìn)產(chǎn)品的性能。但是，必須對(duì)新材料進(jìn)行認(rèn)真的評(píng)價(jià)，以確保其所有性能都滿足要求。應(yīng)當(dāng)記住，新材料的性能和可靠性很少像現(xiàn)有材料那樣為人們所了解。大部分的

22、產(chǎn)品失效和產(chǎn)品責(zé)任事故案件是由于在選用新材料作為替代材料之前，沒(méi)有真正了解它們的長(zhǎng)期使用性能而引起的。產(chǎn)品的責(zé)任訴訟迫使設(shè)計(jì)人員和公司在選擇材料時(shí)，采用最好的程序。在材料過(guò)程中，五個(gè)最常見(jiàn)的問(wèn)題為：（a）不了解或者不會(huì)使用關(guān)于材料應(yīng)用方面的最新最好的信息資料；(b)未能預(yù)見(jiàn)和考慮擦黑年品可能的合理用途（如有可能，設(shè)計(jì)人員還應(yīng)進(jìn)一步預(yù)測(cè)和考慮由于產(chǎn)品使用方法不當(dāng)造成的后果。在近年來(lái)的許多產(chǎn)品責(zé)任訴訟案件中，由于錯(cuò)誤地使用產(chǎn)品而受到傷害的原告控告生產(chǎn)廠家，并且贏得判決）；(c)所使用的材料的數(shù)據(jù)不全或是有些數(shù)據(jù)不確定，尤其是當(dāng)其長(zhǎng)期性能數(shù)據(jù)是如此的時(shí)候；(d)質(zhì)量控制方法不適當(dāng)和未經(jīng)驗(yàn)證；(e)由

23、一些完全不稱職的人員選擇材料。通過(guò)對(duì)上述五個(gè)問(wèn)題的分析，可以得出這些問(wèn)題是沒(méi)有充分理由存在的結(jié)論。對(duì)這些問(wèn)題的研究分析可以為避免這些問(wèn)題的出現(xiàn)指明方向。盡管采用最好的材料選擇方法也不能避免發(fā)生產(chǎn)品責(zé)任訴訟，設(shè)計(jì)人員和工業(yè)界按照適當(dāng)?shù)某绦蜻M(jìn)行材料選擇，可以大大減少訴訟的數(shù)量。從以上的討論可以看出，選擇材料的人們應(yīng)該對(duì)材料的性質(zhì)，特點(diǎn)和加工方法有一個(gè)全面而基本的了解。Machine design theoryThe machine design is through designs the new product or improves the old product to meet the hu

24、man need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question.Carries on

25、each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materi

26、als mechanics and machine manufacture technology has the deep elementary knowledge. If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the human

27、ity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on usi

28、ng creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the

29、completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea,

30、 moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the reques

31、t screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the proc

32、ess confirmation principle of design in this process, with has not unified it after the confirmation new idea. Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come i

33、nto the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method.

34、 In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to sto

35、ps up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts. How does the psychologist frequently discuss causes the

36、machine which the people adapts them to operate. Designs personnels basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating pr

37、ocess. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel

38、, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to solve the following problem: (1) designs whether this product truly does need for the people? Whether there is competitiv

39、e ability (2) does this product compare with other companies existing similar products? (3) produces this kind of product is whether economical? (4) product service is whether convenient? (5) product whether there is sale? Whether may gain?Only has the time to be able to produce the correct answer t

40、o above question. But, the product design, the manufacture and the sale only can in carry on to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of m

41、anufacture to the finally design proposal.Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through d

42、esigns the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always

43、 has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method. Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing aga

44、in appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, workers health and security frequently can attach the new limiting condition to the choice of mat

45、erial. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customers aspect the and so on feedback pressure, can urge the people to ca

46、rry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profound influence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order

47、to can and guarantees the quality in the reasonable cost under the premise to obtain satisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material. Makes any product the first step of work all is designs. Designs usually m

48、ay divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is

49、 whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether h

50、as a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of

51、 components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the pr

52、oduct to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has

53、 the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prot

54、otype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototype does not have the great value. Project engineer is best can

55、 completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the production design stage material replacement by other people, these people are inferior to project engineer to

56、 the product all functions understanding. I n the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the mater

57、ial quantity can quite be easy to guarantee the supply. In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry

58、on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certai