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1、<p>  冷沖模具使用壽命的影響[1]</p><p>  冷沖模具的使用壽命是以沖制出的工件數(shù)量來(lái)計(jì)算的。影響冷沖模壽命的因素很多。主要有模具結(jié)構(gòu)設(shè)計(jì)、制造模具所用凸模和凹模的材料、模具的熱處理質(zhì)量與表面強(qiáng)化、沖模零件的制造精度和冷沖壓材料的選取。除此之外,還有沖模的安裝、調(diào)整、使用以及維修等。</p><p>  1.模具設(shè)計(jì)對(duì)壽命的影響</p><p&

2、gt;  (1)排樣設(shè)計(jì)的影響排樣方法與搭邊值對(duì)模具壽命的影響很大,過(guò)小的搭邊值,往往是造成模具急劇磨損和凸、凹??袀闹匾?。從節(jié)約材料出發(fā),搭邊值愈小愈好,但搭邊值小于一定數(shù)值后,對(duì)模具壽命和剪切表面質(zhì)量不利。在沖裁中有可能被拉人模具問(wèn)隙中,使零件產(chǎn)生毛刺,甚至損壞模具刃口,降低模具壽命。因此,在考慮提高材料利用率的同時(shí),必須根據(jù)零件產(chǎn)量、質(zhì)量和壽命,確定排樣方法和搭邊值。</p><p>  (2)凹模結(jié)

3、構(gòu)的影響對(duì)容易產(chǎn)生應(yīng)力集中而開(kāi)裂的凹模結(jié)構(gòu),可以采用組合結(jié)構(gòu)或鑲拼結(jié)構(gòu),以及預(yù)應(yīng)力結(jié)構(gòu),從而提高模具使用壽命。</p><p>  (3)間隙的影響當(dāng)間隙過(guò)小時(shí),壓縮擠壓利害,摩擦力增大,磨損增大,側(cè)面的磨損加劇,沖裁后卸料和推件時(shí),材料與凸、凹模之間的摩擦還將造成刃口側(cè)面的磨損比端面的磨大大,同時(shí)也容易造成凸、凹模溫度很高,把金屬碎屑吸附在刃口側(cè)面,形成金屬瘤,使凸、凹模出現(xiàn)崩刃或脹裂現(xiàn)象。因此,過(guò)小的間隙對(duì)模

4、具壽命極為不利。間隙太大,會(huì)增加凸模與凹模端面邊緣的集中應(yīng)力,致使壓應(yīng)力急劇增加,于是刃口邊很快屈服變形而失去棱角。因此又增加了沖裁力,進(jìn)而使刃口邊更快磨損,降低模具壽命。但為了減小凸、凹模的磨損,延長(zhǎng)模具使用壽命,在保證沖裁件質(zhì)量的前提下,設(shè)計(jì)時(shí)適當(dāng)采用較大間隙是十分必要的。</p><p>  (4)模具導(dǎo)向結(jié)構(gòu)對(duì)壽命的影響可靠的導(dǎo)向?qū)τ跍p小工作零件的磨損,避免凸、凹??袀欠浅S行У?。特別對(duì)無(wú)問(wèn)隙或小問(wèn)隙沖

5、裁模、復(fù)合模和多工位級(jí)進(jìn)模更為重要。為提高模具壽命,必須根據(jù)工序和零件精度要求,正確選擇導(dǎo)向形式和導(dǎo)向精度,所選擇導(dǎo)向精度應(yīng)高于凸、凹模的配合精度。</p><p>  (5)冷沖壓材料選取的影響冷沖壓材料應(yīng)滿足制件的設(shè)計(jì)要求和沖壓工藝要求,否則容易損傷模具,降低模具使用壽命。冷沖壓材料表面質(zhì)量不好,沖壓時(shí)制件易破裂,也易擦傷模具。冷沖壓材料塑性不好,變形量小,沖壓時(shí)制件易破裂,也易擦傷模具。另外,材料的厚度公差

6、應(yīng)符合國(guó)家標(biāo)準(zhǔn)。因?yàn)橐桓睕_模適用于一定材料的厚度,成形、彎曲、翻邊、引伸模具的凸、凹模結(jié)構(gòu)間隙是直接根據(jù)材料厚度來(lái)確定的。所以材料厚度不均勻,會(huì)導(dǎo)致廢品產(chǎn)生和模具損壞。</p><p>  2.模具材料對(duì)模具壽命的影響</p><p>  模具材料對(duì)模具壽命的影響是模具材料性質(zhì)、化學(xué)成分、組織結(jié)構(gòu)、硬度和冶金質(zhì)量等的綜合反映。其中,材料性質(zhì)和熱處理質(zhì)量影響最為明顯。模具材料性質(zhì)對(duì)模具壽命的

7、影響是很大的。如將同一種工件,使用不同的模具材料做彎曲試驗(yàn),試驗(yàn)結(jié)果:用9Mn2V材料,其壽命為5萬(wàn)次;用Crl2MoV滲氮,其壽命可達(dá)40萬(wàn)次。因此,在選用材料時(shí),應(yīng)根據(jù)制件的批量大小,合理選用模具材料。模具工作零件的硬度對(duì)模具壽命的影響也很大。但并不是硬度愈高、模具壽命愈長(zhǎng)。這是因?yàn)橛捕扰c強(qiáng)度、韌性及耐磨性等有密切的關(guān)系。有的沖模要求硬度高,壽命長(zhǎng)。如采用T10鋼制造沖模,硬度為54~58HRC,只沖幾千次,制件毛刺就很大。如果將硬

8、度提高到60~64HRC,則刃磨壽命可達(dá)2~3萬(wàn)次。但如果繼續(xù)提高硬度,則會(huì)出現(xiàn)早期斷裂。有的沖模硬度不宜過(guò)高,如采用Crl2MoV制造凹模硬度為58~62HRC時(shí),一般壽命為2—3萬(wàn)件,失效形式是崩刃和開(kāi)裂以及如果將硬度降到54~58HRC,壽命提高到5~6萬(wàn)件,但硬度降低到50~53HRC會(huì)出現(xiàn)凹模刃口易磨鈍現(xiàn)象。由此可見(jiàn),模具硬度必須根據(jù)材料性質(zhì)和失效形式而定。應(yīng)使硬度、強(qiáng)度、韌性及耐磨性、耐疲勞強(qiáng)</p><

9、p>  3.模具的熱處理質(zhì)量與表面強(qiáng)化對(duì)壽命的影響</p><p>  模具的熱處理質(zhì)量對(duì)模具的性質(zhì)與使用壽命影響很大。實(shí)踐證明,模具工作零件的淬火變形與開(kāi)裂,使用過(guò)程中早期斷裂,雖然與材料的冶金質(zhì)量、鍛造質(zhì)量、模具結(jié)構(gòu)及加工有關(guān),但與模具的熱處理關(guān)系更大。根據(jù)模具失效原因的分析統(tǒng)計(jì),熱處理不當(dāng)引起的失效占50% 以上。實(shí)踐證明,高級(jí)的模具材料必須配以正確的熱處理工藝,才能真正發(fā)揮材料的潛力。模具工作零件表

10、面強(qiáng)化處理的目的,是獲得外硬內(nèi)韌的效果,從而得到硬度、耐磨性、韌性、耐疲勞強(qiáng)度的良好配合。模具表面強(qiáng)化處理方法很多,表面處理的新技術(shù)工藝發(fā)展很快。除氮碳共滲和離子氮化、滲硼、滲鈮、滲釩、表面鍍硬鉻和電火花強(qiáng)化外,化學(xué)氣相沉積(CVD)和物理氣相沉積(PVD)已逐步采用。經(jīng)CVD和PVD處理后,模具表面覆蓋一層超硬物質(zhì),如TiC、TiN等。硬度極高、耐磨性、耐蝕性、抗黏合性很好,可提高模具壽命幾倍到幾十倍。</p><

11、p>  4.沖模零件的制造精度對(duì)模具壽命的影響</p><p>  沖模制造的精度與使用壽命關(guān)系很大,特別是模具表面粗糙度對(duì)模具影響很大。如用Crl2MoV鋼制造落料模,如果表面粗糙度值R =1.6 m時(shí),其壽命為3萬(wàn)件左右。如經(jīng)精拋光,表面粗糙度值R =0.4 m,壽命可提高到4—5萬(wàn)件。因此,對(duì)模具工作零件表面,一般都要經(jīng)過(guò)磨削、研磨、拋光等精加工和精細(xì)加工。</p><p> 

12、 5.其他方面對(duì)模具壽命的影響</p><p>  (1)壓力機(jī)的精度不高,也易使沖模損壞。</p><p>  (2)沖模在壓力機(jī)上安裝的正確與否及操作者的技術(shù)水平高低,對(duì)模具壽命也有很大影響。</p><p>  (3)沖模的保管和維護(hù)好壞,以及使用潤(rùn)滑劑的情況,也影響模具使用壽命。</p><p>  冷沖模凸凹模間隙控制和調(diào)整方法&l

13、t;/p><p>  冷沖壓模具凸、凹模間隙的大小和均勻程度直接影響沖裁件的質(zhì)量和模具的使用壽命的長(zhǎng)短。在保證沖裁件間隙時(shí)裝配也是模具制造中十分重要的環(huán)節(jié),而且裝配質(zhì)量將直接影響凸、凹模的間隙是否均勻。比如加工時(shí)凸、凹模的尺寸精度雖已達(dá)到要求,但是在裝配時(shí)如果調(diào)整不好,就會(huì)造成間隙不均勻,沖出的零件有毛邊。甚至?xí)_出不合格的零件。模具裝配的關(guān)鍵是要控制凸、凹模的相對(duì)位置,以保證凸、凹模的間隙正確、均勻并能沖出合格的零

14、件。1.模具在裝配前應(yīng)關(guān)注的問(wèn)題[2]  凸、凹模間隙既與模具本身零件的精度有關(guān),也與裝配時(shí)的裝配工藝是否合理有關(guān)。為了保證凸、凹模的位置正確和間隙均勻,模具從設(shè)計(jì)、加工到裝配整個(gè)環(huán)節(jié)要注意的問(wèn)題如下: (1)凸、凹模的正確設(shè)計(jì)和制造  設(shè)計(jì)模具時(shí)首先應(yīng)根據(jù)沖裁件的斷面質(zhì)量、模具使用壽命等因素選擇合理的凸、凹模間隙。并要考慮到模具在使用過(guò)程中的磨損使間隙增大,一般在設(shè)計(jì)模具時(shí)采用最小合理

15、間隙。并在制造過(guò)程中保證模具零件的加工質(zhì)量和精度,在裝配過(guò)程中確保凸、凹模間隙均勻,這對(duì)于加工復(fù)雜形狀零件十分關(guān)鍵。 (2)裝配方法的選擇要合理  沖模裝配方法大致包括直接裝配法和配</p><p><b> ?。?)墊片調(diào)整法</b></p><p>  墊片調(diào)整間隙法簡(jiǎn)便、應(yīng)用廣泛。如圖1所示,合模后墊好等高墊鐵,將墊片包在凸模上使凸

16、模進(jìn)入凹模內(nèi),觀察凸、凹模的間隙狀況。如果間隙不均勻,用敲擊凸模固定板的方法調(diào)整間隙,然后擰緊上模固定螺釘。最后放紙?jiān)嚊_,觀察切紙上四周毛刺均勻程度,從而判斷凸、凹模間隙是否均勻,再調(diào)整間隙直至沖裁毛刺均勻?yàn)橹?。最后將上模座與固定板配鉆、鉸定位銷(xiāo)孔,并打入銷(xiāo)釘定位。這種方法廣泛適用于沖裁材料較厚的大間隙沖模和彎曲、拉深成形模具的間隙控制。(4)化學(xué)法  當(dāng)凸、凹模的形狀復(fù)雜時(shí),用上述幾種方法調(diào)整間隙較困難時(shí),這時(shí)可用

17、化學(xué)方法來(lái)控制間隙,常用的是電鍍法。電鍍法是在凸模工作端表面鍍上一層銅或鋅來(lái)代替墊片。鍍層厚度與單邊隙相同,刃人凹??變?nèi),檢查上下移動(dòng)無(wú)阻滯現(xiàn)象即可裝配緊固。鍍層在沖模使用過(guò)程中會(huì)自然脫落,無(wú)需去除。此法鍍層均勻,可提高裝配間隙的均勻性。 (5)工藝措施調(diào)整法 采用工藝措施調(diào)整模具間隙主要有2種方法: 1.尺寸法  加工凸模時(shí),將凸模前端適當(dāng)加長(zhǎng),加長(zhǎng)段截面尺寸加工到與凹模型孔尺寸相

18、同。裝配時(shí),使凸模進(jìn)入凹模型孔,自然形成沖裁間隙,然后將凸模連同凸模固定板一起與上模座配</p><p>  Die Life of cold stamping die and influence</p><p>  Die with the life of the workpiece by punching out the number of terms. Many factors af

19、fect the life Die. There are die structure design, manufacture molds used in the punch and die materials, die quality and surface hardening heat treatment, precision die manufacturing parts and cold stamping materials se

20、lection. In addition, there are die installation, adjustment, use and maintenance. 1. Die Design on Life (1) Layout design of layout methods and take the boundary value a great impact on the </p><p>  Cold

21、 die clearances between control and adjusting method</p><p>  Cold stamping mould convex, concave die size and distribution of the clearance degree directly affect the quality of the blanking pieces and the

22、length of the service life of the die. In guarantee blanking pieces space is mould manufacturing assembly very important link, and assembly quality will directly influence the convex, concave die if the clearance between

23、 the uniform. Such as the process of convex, concave die size precision although already meet the requirements, but in assembling if ad</p><p>  1. Die before assembly the problems that should be paid attent

24、ion[2] </p><p>  Convex, concave die and mould parts itself is clearance of the precision, and the assembly of the assembly process is reasonable. In order to ensure that the position of the convex, concave

25、die correctly and gaps even, mould design, processing to assembly from the whole link should pay attention to the following questions: </p><p> ?。?)Convex, concave die design and manufacture of the right <

26、;/p><p>  Design should be based on the above all when die cutting the section of a quality, service life of die factors such as the reasonable selection of convex, concave die clearance. And to consider the mo

27、uld in the process of using that gap wear increases, general in the design the least reasonable clearance when mould. And in the manufacturing process can ensure the parts processing precision and quality, in the assembl

28、y process ensure convex, concave die gap even, this for processing complex shape</p><p> ?。?)Assembly method the choice should be reasonable </p><p>  Die assembly method include roughly assembl

29、y method and direct with assembly method. Before the assembly must be carefully study mold assembly drawing, full consideration and analysis of the structure characteristics of punching die, die parts processing technolo

30、gy and processing accuracy etc, in order to choose convenient, accurate and reliable assembly method to ensure the quality of blanking pieces. </p><p>  2. Convex, concave die gap between the control and adj

31、ustment of the method[3] </p><p>  Convex, concave die clearance control, should according to die structure, clearance size, blanking pieces of quality and practical assembly condition to selected. Convex, c

32、oncave die gap between the control and adjustment method have the following kinds. </p><p> ?。?)Pervious to light method </p><p>  Will convex, concave die after molmerged, shone a light on the

33、underside, observe the convex, concave die around through light and distribution to judge the size of the clearance and uniformity. If not even, to adjust to evenly between fixed again, this method is suitable for small

34、gap plate stamping die. </p><p> ?。?)Feeler method </p><p>  Will convex, concave die after molmerged, convex, concave die into the thickness of unilateral clearance feeler convex, concave die g

35、aps in each direction. Then tighten the screw on mode. Finally put paper to stamping and will last mould seat and fixed on board with drilling, reaming positioning pin hole, and at a pin location. </p><p>  

36、(3)Gaskets DiaoZhengFa </p><p>  Gasket adjustment method is simple, convenient, clearance is used widely. As shown in figure 1 shows, the mat with good contour mat iron, will gaskets wrapped in the punch to

37、 the punch into the concave mould, observe the convex, concave die clearance condition. If clearance does not even, with striking the protruding models of fixed plate method clearance adjustment, then tighten the screw o

38、n mode. Finally put paper to stamping, observation on paper cutting around burr and even rate to judge whe</p><p>  (4) Chemical method </p><p>  When the convex, concave die complex shape, the

39、use of the above several methods more difficult to adjust the gap, the chemical method can be used to control the gap, the plating method is used. Plating method is the punch in the work surface coated with copper or zin

40、c instead of washers. The plating thickness and unilateral gap is same, blade people concave die hole, and check the move without block phenomenon can assembly tighten. Coating in use process will die fall off naturally,

41、 need not re</p><p>  (5) Technology DiaoZhengFa measures </p><p>  The main technological measures to adjust the gap between two kinds of the mould method: </p><p>  1. Size method

42、 </p><p>  Processing of the punch, will the punch front-end appropriate lengthen, extended period of section size and sunken model hole processing to the same size. Assembly, make the punch into female mode

43、l hole, natural form the cutting clearance, and then to the punch with fixed together with the punch mould seat on board with the pin for fixed and will last longer period of the punch front can remove form even clearanc

44、e. </p><p>  2. Positioning hole method </p><p>  Process positioning hole method and the inside of the progressive die principle about. Processing, the punch in fixed board and concave die on t

45、he same position processing two positioning hole, can will locate hole and the mold cavity a cut out. Assembly, in the positioning hole insert pins to ensure that gap. </p><p>  (6) Standard model method <

46、;/p><p>  According to the drawing wedm in advance in processing a standard model or the qualified stamping parts, to adjust the assembly put it in between convex, concave die, upper and lower die relative moti

47、on can be reasonable degree when appropriate. </p><p>  (7) Measurement method </p><p>  Measuring method of the measuring tool have feeler. A feeler method after the adjustment convex, concave

48、die clearance good uniformity, it is the commonly used method. Assembly, the punch in the concave die in the hole, convex, concave die according to the size of the clearance choose different specifications of the feeler

49、insert convex, concave die clearance, inspection concave die around the blade gap everywhere, and according to the measured results adjustment. If the adjustment of the punch </p><p>  (8) Adjustment method

50、of repair match means</p><p>  Die in use after period of time, because the convex, concave die normal wear and tear. To working parts inspection, if products produce burr, convex, concave die dull and colla

51、pse the blade factors, it is because of the convex, concave die clearance for wear changed, namely bigger or not even. To make the convex, concave die restored to the original gap value out of parts can use the following

52、 method to qualified for repair match means. </p><p>  1. Convex, concave die clearance greaten repair match means method </p><p>  General dies in use after period of time, because normal wear

53、will make convex, concave die gap increase gradually, thus to make the work and so on a series of problems produced burr. This kind of circumstance, can use first thickness is equal to one of the KuaiGui insert gap betwe

54、en the convex, concave die, if convex, concave die clearance does not too big, the grinding work part of the blade continue to use, can improve the quality of stamping. When gap value too big when, the recoverable high&l

55、t;/p><p>  2. Convex, concave die clearance does not even repair match means method </p><p>  Dies after a period of using, clearance does not even can make blunt a local produce burr or the blade

56、was edge chewed. In normal wear punching die, because after wearing precision guide device that reduce convex, concave die happen relatively migration, respectively in the guide pin and a guide to cover on the plating ch

57、romium layer the restored to its original size, again through the pressure seal the law will remove file high. If it is due to the pins loosening lose positioning function and c</p><p><b>  參考文獻(xiàn)</b&

58、gt;</p><p>  [1]陸茵. 冷沖模具使用壽命的影響及對(duì)策[J] 金屬加工(冷加工) 1950 46-47.</p><p>  [2]謝昱北. 《模具設(shè)計(jì)與制造》.2005年 北京 北京大學(xué)出版社.</p><p>  [3]薛獸翔. 《沖壓模具與制造》.2004年 北京 北京化學(xué)工業(yè)出版社.</p><p>  [4]洪麗華

59、.陳永祿. 中國(guó)模具工業(yè)現(xiàn)狀和模具技術(shù)發(fā)展趨勢(shì)[J]  機(jī)電技術(shù).2007年 第二期 96-98</p><p>  [5] CHEN Zhi-ming ZHANG Hai-ou WANG Gui-lan. China's mold industry current situation and development[J] Forging & Stamping Technology.

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