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- 12 -
江陰職業(yè)技術(shù)學(xué)院
模具綜合技能訓(xùn)練
(冷沖模部分)
課題啤酒起支撐板沖孔落料模設(shè)計(jì)
同課題學(xué)生姓名
專業(yè) 模具設(shè)計(jì)與制造
學(xué)生姓名
班級(jí)
學(xué)號(hào)
指導(dǎo)教師
完成日期
目錄
一、零件工藝性分析 1
1零件沖裁工藝性分析
2
2確定沖裁工藝方案
2
3確定模具總體結(jié)構(gòu)方案 3
二、工藝與設(shè)計(jì)計(jì)算
3
1沖裁力計(jì)算
3
2推件力計(jì)算
3
3壓力中心的計(jì)算
4
4計(jì)算凸、凹模刃口尺寸及公差
4
三、模具零、部件設(shè)計(jì)選用
5
1、凹模設(shè)計(jì)
5
2、凸模設(shè)計(jì)
6
四、模架設(shè)計(jì)
7
五、參考文獻(xiàn)······························································································································ 10
設(shè)計(jì)體會(huì)·········································································································································· 11
一、零件工藝性分析
材 料:Q235號(hào)鋼
材料厚度:2 mm
在工藝安排上應(yīng)該先落料,再彎曲,最后沖孔便可以達(dá)到圖紙要求。
根據(jù)以上分析,該工件宜先落料,再彎曲最后沖孔達(dá)到圖紙要求。
零件3D模型
零件展開圖模型
1.1零件沖裁工藝性分析
1)制造精度
工件尺寸公差按IT10/IT12級(jí)制造。查標(biāo)準(zhǔn)公差表,各尺寸公差無其他特殊要求。查有關(guān)手冊(cè)可知,利用普通沖裁方式可以達(dá)到零件圖紙要求。
2)結(jié)構(gòu)與尺寸
工件結(jié)構(gòu)簡單,外形對(duì)稱??椎闹睆剑ㄏ鄬?duì)厚度)大,孔壁>1.5t,這些結(jié)構(gòu)因素均宜沖裁。
3)材料
碳素結(jié)構(gòu)鋼Q235,抗拉強(qiáng)度σb=380~470MPa,抗剪強(qiáng)度τ=310~380 MPa,斷后伸長率δ10=21~25%。此材料具有較高的彈性和良好的塑性,其沖裁加工性能比較好。
根據(jù)以上分析,該零件的工藝性較好,可以進(jìn)行沖裁加工。
1. 2確定沖裁工藝方案
方案1 單工序方案,優(yōu)點(diǎn):零件容易制造,缺點(diǎn):產(chǎn)品精度低,生產(chǎn)效率低
方案2 復(fù)合模設(shè)計(jì),優(yōu)點(diǎn):產(chǎn)品精度高,生產(chǎn)效率高;缺點(diǎn):零件不易制造。綜合我校情況及我們小組情況,選擇方案2
由此確定工序如下:下料——落料——彎曲——沖孔——檢驗(yàn)。
1. 3確定模具總體結(jié)構(gòu)方案
1)模具類型
根據(jù)零件的沖裁工藝方案,采用導(dǎo)柱式單工序沖裁模。
2)操作與定位方式
雖然零件的生產(chǎn)批量較大,但合理安排生產(chǎn)可用手工送料方式能夠達(dá)到批量要求,而且能降低模具成本,因此采用手工送料方式??紤]零件尺寸以及厚度,為了便于操作和保證零件的精度,宜采用導(dǎo)料板導(dǎo)向、固定擋料銷定距的定位方式。
3)卸料與出件方式
采用剛性卸料方式,手動(dòng)取出產(chǎn)品。
4)模架類型與精度
由于零件厚度較薄,沖裁間隙較小,因此采用受力平衡、導(dǎo)向平穩(wěn)的對(duì)角導(dǎo)柱模架??紤]零件精度以及沖裁間隙,采用Ⅰ級(jí)模架精度。
二、工藝與設(shè)計(jì)計(jì)算
1、沖裁力計(jì)算
沖裁力是設(shè)計(jì)模具、選擇壓力機(jī)的重要參數(shù)。計(jì)算沖壓力的目的是為了合理地選擇沖壓設(shè)備和設(shè)計(jì)模具。選用沖壓設(shè)備的標(biāo)稱壓力必須大于所計(jì)算的沖裁力,所設(shè)計(jì)的模具必須能傳遞和承受所計(jì)算的沖裁力,以適應(yīng)沖裁的要求。沖裁力包括沖裁力、卸料力、推件力、頂件力的計(jì)算。
沖裁力計(jì)算及壓力機(jī)的選擇
沖裁力的大小主要與材料性質(zhì)、厚度、沖裁件周長、模具間隙大小及刃口鋒利程度有關(guān)。
一般對(duì)于普通平刃口的沖裁,其沖裁力F可按下式計(jì)算:
Fc= K·L·t·Rm (2-3)
式中: F —— 沖裁力, N;
L —— 沖裁件的沖裁長度, mm;
t —— 板料厚度,mm;
Rm—— 材料的抗拉強(qiáng)度, Mpa;
沖孔力:F孔1=1.3·3.14·6·2·390=19.1KN
F孔2=1.3·3.14·10·2·390=31.8KN
Fc=19.1+31.8=50900N
2、推件力計(jì)算
從凸模上卸下緊箍著的材料所需的力叫卸料力;把落料件從凹模洞口順著沖裁方向推出去的力叫推件力;
卸料力和推件力通常采用經(jīng)驗(yàn)公式進(jìn)行計(jì)算,見式(2-4)。
卸料力:F卸=Kx*Fc
推件力:F推=n·KT·FC (2-4)
式中: KX、Kt—— 分別為卸料力、推件力系數(shù),其值見表(2—4);
N=h/t;
表2. 4 推件力、頂件力、卸料力系數(shù)
料厚/(mm)
Kt
K頂
Kx
鋼
≤0.1
>0.1~0.5
>0.5~2.5
>2.5~6.5
0.065~0.075
0.045~0.055
0.04~0.05
0.03~0.04
0.1
0.063
0.055
0.045
0.14
0.08
0.06
0.05
推件力:F推=n·Kt·Fc圓= 4×0.055×50.9 KN
= 11.198 KN
總沖壓力:
F = Fc+F推 =11.198KN+50.9KN=62.098KN
從滿足沖壓工藝力的要求看,可選用63KN開式壓力機(jī)。
3、壓力中心的計(jì)算
X=0.14 Y=0.23
4、計(jì)算凸、凹模刃口尺寸及公差
模具刃口尺寸及公差是影響沖裁件精度,因而,正確確定沖裁凸模和凹模刃口的尺寸及公差,是沖模設(shè)計(jì)的重要環(huán)節(jié)。
1)凸、凹模刃口尺寸公差計(jì)算的原則
實(shí)踐證明,沖孔尺寸接近于其凸模刃口尺寸。沖孔時(shí)取凸模作為設(shè)計(jì)的基準(zhǔn)件。計(jì)算凸模和凹模尺寸時(shí)應(yīng)遵循的原則如下:
(1)沖孔時(shí),先確定凸模刃口尺寸。凸模刃口的基本尺寸取接近或等于孔的最大極限尺寸,以保證凸模磨損在一定范圍內(nèi)也可使用。而凹模的基本尺寸則按凸模刃口的基本尺寸加上一個(gè)最小間隙值。
(2)在確定模具刃口制造公差時(shí),既要能保證工件的精度要求,又能保證合理的間隙數(shù)值。一般模具制造精度比工件精度高3~4級(jí)。
對(duì)沖孔6mm、10mm,采用凸、凹模分開加工的方法,其凸、凹模刃口部分尺寸計(jì)算如下:
根據(jù)材料厚度,查手冊(cè)可得:
Zmax=0.360mm
Zmin=0.246mm
Zmax-Zmin=0.114mm
查手冊(cè)得,凸、凹模制造公差:
沖孔尺寸R3、R5:δ凸=δ凹=0.020mm.
對(duì)于沖孔R(shí)3、R5為0.02mm。
由于凸凹模均滿足|δ凸|+|δ凹|≤Zmax-Zmin條件,故可采用凹凸模,
凹凸模分開加工。
確定凸模、凹模工作部分尺寸
因零件上的尺寸均為未注尺寸公差,故按IT14級(jí)計(jì)算
凸模r3 → d6:△=0.30mm
r5 → d10:△=0.36mm
查教材P34表2、5得摩擦系數(shù)x=0.5
d凸 =(d+x.△)0-δ凸=(6+0.5×0.3)0-0.020=6.150-0.020mm
d凸凹=(d+△x+Zmin)0+δ凹=6.396+0.0200mm
d凸10=(d+x.△)0-δ凸=(10+0.5×0.43)0-0.020=10.2150-0.020mm
d凸凹10=(d+△x+Zmin)+δ凹0=10.5610+0.020mm
三、模具零、部件設(shè)計(jì)選用
1、凹模設(shè)計(jì)
凹模結(jié)構(gòu)
整體式:其優(yōu)點(diǎn)是模具簡單,強(qiáng)度好,制造精度高。缺點(diǎn)是非工作部分也用模具剛制造,制造成本較高;若刃口損壞,需整體更換。主要適用于中小型及尺寸精度要求高的制件
組合式: 其凹模工作部分采用模具鋼制造,非工件部分采用普通材料制造,制造成本低,維修方便。缺點(diǎn)是結(jié)構(gòu)稍復(fù)雜,制造精度比整體式有所降低。主要適用于大中型及精度要求不太高的制件。
鑲拼式: 凹模型腔由兩個(gè)或兩個(gè)以上的零件組成。這種結(jié)構(gòu)使零件加工方便,降低了復(fù)雜模具的加工難道,易損部分易更換,維修費(fèi)用低。缺點(diǎn)是制件的精度低,裝配要求高。主要適用于形狀復(fù)雜的制件
根據(jù)以上分析選用整體式結(jié)構(gòu)
因沖件的批量較大,考慮凹模的磨損和保證沖件的質(zhì)量,凹模刃口采用直刃壁結(jié)構(gòu),刃壁高度取6mm,凹模輪廓尺寸計(jì)算如下:
Ha=Kb=194.29*0.2=38.858mm
C=(1.5——2.0)*Ha=(58.287~77.716)
式中h——凹模厚度,[h]為mm;
C——凹模壁厚指最小壁厚
2、凸模設(shè)計(jì)
凸模結(jié)構(gòu)
整體式: 凸模的工作部分和固定部分做出一體,按其按裝固定部分的情況又可分為直通式和臺(tái)階式直通式凸模工作部分和固定部分的形狀與尺寸一致,輪廓為曲面或比較復(fù)雜,機(jī)械加工教困難;臺(tái)階式凸模工作部分和固定部分的形狀與尺寸不一致,一般采用機(jī)械加工,當(dāng)形狀復(fù)雜時(shí),成型部分常采用成型磨削加工。
鑲拼式凸模: 是將凸模分成若干分體零件加工,然后用圓注銷連成一體,安裝在凸模固定板上,這樣可降低凸模的加工難度。
組合式凸模:由基體部分和工作部分組合而成,工作部分使用模具剛制造,基體部分可采用普通鋼材來制造,從而節(jié)約了優(yōu)質(zhì)鋼材,降低模具成不。此種型式適合于大型制件的凸模
凸模長度計(jì)算:
H=h1+h2+h3+H=50mm h1——凸模固定板厚度
h2——固定卸料板厚度
h3——導(dǎo)料板厚度 H——自由尺寸
(1)凸模固定板25mm
(2) 凸模墊板 12mm
四、模架設(shè)計(jì)
1、模架選擇
選用后側(cè)滑動(dòng)導(dǎo)柱導(dǎo)套標(biāo)準(zhǔn)模架,由工件最大外形尺寸95mm,及一定的凹模壁厚30mm,在按其標(biāo)準(zhǔn)選擇具體結(jié)構(gòu)尺寸:
上模座:315×200×45
下模座:315×200×55
壓入式模柄 :50×95
2、模具總裝圖及主要零件圖的設(shè)計(jì)
總裝圖
凹模
沖孔凸模
凸模固定板
卸料板
五、參考文獻(xiàn)
1、陳錫棟、靖穎怡主編《沖模設(shè)計(jì)應(yīng)用實(shí)例》——機(jī)械工業(yè)出版社
2、張鼎承主編《沖模設(shè)計(jì)手冊(cè)》 ——機(jī)械工業(yè)出版社
3、陳錫棟、周小玉主編《實(shí)用模具技術(shù)手冊(cè)》——機(jī)械工業(yè)出版社
4、鐘毓斌主編《沖壓工藝與模具設(shè)計(jì)》——機(jī)械工業(yè)出版社
5、馮柄堯主編《模具設(shè)計(jì)與制造簡明手冊(cè)》——上海出版社
設(shè)計(jì)體會(huì)
本次設(shè)計(jì)為課程設(shè)計(jì),各項(xiàng)要求均比較嚴(yán)格,為了能更加好的完成設(shè)計(jì)任務(wù),我從圖書館和網(wǎng)上查閱了大量的冷沖模設(shè)計(jì)資料。這為我在后來設(shè)計(jì)階段省下了不注寶貴的時(shí)間表。除了對(duì)知識(shí)的查閱,我還翻出了大學(xué)三年來所學(xué)的重點(diǎn)專業(yè)知識(shí),重新系統(tǒng)的去學(xué)習(xí)和撐握,為設(shè)計(jì)做準(zhǔn)備。
模具設(shè)計(jì)中許多問題的解決都是通過從實(shí)踐所得的數(shù)據(jù)來確定、并適當(dāng)?shù)淖龀鲞x擇,如:沖裁間隙的確定等。
本次設(shè)計(jì)的工作量相對(duì)于課程設(shè)計(jì)大了很多,特別對(duì)圖線的要求。繪圖成了快速完成設(shè)計(jì)的最大障礙,繪圖軟件主要用CAD。這是我們大二所學(xué)的知識(shí),因?yàn)榄h(huán)境等因素的制約,想提高繪圖技巧是我必須要完成的任務(wù)。
這次設(shè)計(jì)是我們參加工作前的最后一次設(shè)計(jì)。完成它就是對(duì)我們?nèi)陙硭鶎W(xué)知識(shí)的一次系統(tǒng)應(yīng)用,為我將來參加實(shí)踐工作做好鋪墊,是我們對(duì)自身所學(xué)的一次檢驗(yàn),讓我們受益良多。
12
江陰職業(yè)技術(shù)學(xué)院
加工工藝過程卡
零件圖號(hào)
JYPCCCY-CE-1-01
共1頁
零件名稱
沖孔凸模
第1頁
工序號(hào)
工序名稱
工序內(nèi)容
設(shè)備
工序簡圖
檢驗(yàn)
1
下料
鋸床下圓棒料
鋸床
2
熱處理
退火
3
粗車
初步車出外緣
車床
4
磨平面
磨上下平面
磨床
5
熱處理
保證HRC56-60
6
磨平面
磨上下平面及相鄰兩側(cè)至尺寸
磨床
7
鉗工精修
全面達(dá)到設(shè)計(jì)要求
標(biāo)記
處數(shù)
更改文件號(hào)
簽字
日期
編制
校對(duì)
審核
會(huì)簽
江陰職業(yè)技術(shù)學(xué)院
加工工藝過程卡
零件圖號(hào)
JYPCCCY- CE-1-03
共1頁
零件名稱
凹模
第1頁
工序號(hào)
工序名稱
工序內(nèi)容
設(shè)備
工序簡圖
檢驗(yàn)
1
下料
按尺寸下料350×200×40
2
熱處理
退火
3
粗銑
銑六面達(dá)300.2×150.2×35.5,且互為直角
銑床
4
磨平面
磨上下平面
磨床
5
鉗工劃線
畫出各孔位置線,型孔輪廓線
6
加螺釘孔、銷孔及工工藝孔
1、鉆孔φ6、φ10
2、加工工藝孔φ10
3、鉆鉸2-φ10
鉆床
7
銑長槽
達(dá)到設(shè)計(jì)要求
銑床
8
熱處理
保證HRC58-61
9
磨平面
磨上下平面及相鄰兩側(cè)至尺寸
磨床
10
線切割
線切割型孔達(dá)到設(shè)計(jì)要求
線切割機(jī)
11
鉗工精修
全面達(dá)到設(shè)計(jì)要求
標(biāo)記
處數(shù)
更改文件號(hào)
簽字
日期
編制
校對(duì)
審核
會(huì)簽
江陰職業(yè)技術(shù)學(xué)院
加工工藝過程卡
零件圖號(hào)
JYPCCCY-ZJ-1-04
共1頁
零件名稱
凸模固定板
第1頁
工序號(hào)
工序名稱
工序內(nèi)容
設(shè)備
工序簡圖
檢驗(yàn)
1
下料
按尺寸下料350×200×40
2
粗銑
銑六面達(dá)300.2×150.2×35.5,且互為直角
銑床
3
磨平面
磨上下平面
磨床
4
鉗工劃線
畫出各孔位置線,型孔輪廓線
5
銑槽
達(dá)到設(shè)計(jì)要求
銑床
6
加螺釘孔、銷孔及工工藝孔
1、鉆孔φ6、φ10
2、鉆孔4-φ20
3、鉆鉸2-φ10
鉆床
7
磨平面
磨上下平面及相鄰兩側(cè)至尺寸
磨床
8
鉗工精修
全面達(dá)到設(shè)計(jì)要求
標(biāo)記
處數(shù)
更改文件號(hào)
簽字
日期
編制
校對(duì)
審核
會(huì)簽
江陰職業(yè)技術(shù)學(xué)院
加工工藝過程卡
零件圖號(hào)
JYPCCCY- CE-1-05
共1頁
零件名稱
卸料板
第1頁
工序號(hào)
工序名稱
工序內(nèi)容
設(shè)備
工序簡圖
檢驗(yàn)
1
下料
按尺寸下料350×200×40
2
熱處理
退火
3
粗銑
銑六面達(dá)300.2×150.2×35.5,且互為直角
銑床
4
磨平面
磨上下平面
磨床
5
鉗工劃線
畫出各孔位置線,型孔輪廓線
6
加螺釘孔、銷孔及工工藝孔
1、鉆孔φ9攻螺紋φ20
2、鉆孔3-φ10
3、工藝孔φ10
鉆床
7
熱處理
保證HRC43-48
8
磨平面
磨上下平面及相鄰兩側(cè)至尺寸
磨床
9
線切割
線切割型孔達(dá)到設(shè)計(jì)要求
線切割機(jī)
10
鉗工精修
全面達(dá)到設(shè)計(jì)要求
標(biāo)記
處數(shù)
更改文件號(hào)
簽字
日期
編制
校對(duì)
審核
會(huì)簽
外文翻譯
專 業(yè) 名 稱 機(jī)械設(shè)計(jì)制造及其自動(dòng)化
班 級(jí) 學(xué) 號(hào) 078105232
學(xué) 生 姓 名 冼 振 源
指 導(dǎo) 教 師 陳 為 國
填 表 日 期 2011 年 1 月 17 日
General all-steel punching die’s punching accuracy
Accuracy of panel punching part is display the press accuracy of the die exactly. But the accuracy of any punching parts’ linear dimension and positional accuracy almost depend on the blanking and blanking accuracy,. So that the compound mould of compound punching’s accuracy, is typicalness and representation in the majority.
Analyse of the die’s accuracy
For the analyse of pracyicable inaccuracy during production of dies to inactivation, we could get the tendency when it is augmentation in most time. From this we could analyse the elements. When the new punch dies pt into production to the first cutter grinding, the inaccuracy produced called initial error; if the die grinding more than twenty times, until it’s discard, the inaccuracy called conventional error; and before the dies discard, the largest error of the last batch permit, called limiting error. at job site, the evidence to confirm life of sharpening is the higher of the blanking, punched hole or punched parts. Because all finished parts had been blanked ,so it is especially for the compound dies. Therefore, the analyse of burr and measurement is especially important when do them as enterprise standardization or checked with <>.
The initial error usually is the minimal through the whole life of die. Its magnitude depend on the accuracy of manufacture, quality, measure of the punching part, thickness of panel, magnitude of gap and degree of homogeneity. The accuracy of manufacture depend on the manufacture process. For the 1 mm thicked compound punching part made in medium steel, the experimental result and productive practice all prove that the burr of dies which produced by spark cutting are higher 25%~~30% than produced by grinder ,NC or CNC. The reason is that not only the latter have more exact machining accuracy but also the value of roughness Ra is less one order than the formmer, it can be reached 0.025μm. Therefore, the die’s initial blanked accuracy depends on the accuracy of manufacture, quality and so on.
The normal error of the punch die is the practicable error when the fist cutter grinding and the last cutter grinding before the die produce the last qualified product. As the increase of cutter grinding, caused the measure the nature wear of the dies are gradual increasing, the error of punching part increase also, so the parts are blew proof. And the die will be unused. The hole on the part and inner because the measure of wear will be small and small gradually, and its outside form will be lager in the same reason. Therefore, the hole and inner form in the part will be made mould according to one-way positive deviation or nearly equal to the limit max measure. In like manner, the punching part’s appearance will be made mould according to one-way negative deviation or nearly equal to limit mini measure. For this will be broaden the normal error, and the cutter grinding times will be increased, the life will be long.
The limit error in punching parts are the max dimension error which practicable allowed in the parts with limit error. This kind of parts usually are the last qualified products before the die discard.
For the all classes of dies, if we analyse the fluctuate, tendency of increase and decrease and law which appeared in the die’s whole life, we will find that the master of the error are changeless; the error that because the abrade of the cutter and impression will be as the cutter grinding times increased at the same time. And that will cause the error oversize gradually; and also have another part error are unconventional , unforeseen. Therefore, every die’ s error are composed of fixed error, system error, accident error and so on.
1. fixed error
At the whole process when the New punching die between just input production to discard, the changeless master error that in qualified part are called fixed error. It’s magnitude is the deviation when the die production qualified products before the first cutter grinding. Also is the initial error, but the die have initial punching accuracy at this time. Because of the abrade of parts, the die after grinding will be change the dimension error. And the increment of deviation will oversize as the times of cutter grinding. So the punching accuracy after cutter grinding also called “grinding accuracy” and lower tan initial accuracy. The fixed error depend on the elements factor as followed :
(1) the material , sorts, structure, (form) dimension, and thick of panel
the magnitude of punching gap and degree of homogeneity are have a important effect for the dimension accuracy. Different punching process, material, thick of panel, have completely different gap and punching accuracy. A gear H62 which made in yellow brass with the same mode number m=0.34, 2mm thick and had a center hole, when the gap get C=0.5%t (single edge) , and punched with compound punching die, and the dimension accuracy reached IT7, the part have a flat surface ,the verticality of tangent plane reached 89.5°, its roughness Ra magnitude are 12.5μm, height of burr are 0.10mm; and the punching part are punched with progressive die, the gap C=7%t (single edge) , initial accuracy are IT11, and have an more rough surface, even can see the gap with eyes. In the usual situation, flushes a material and its thickness t is theselection punching gap main basis. Once the designation gap haddetermined flushes the plane size the fixed error main body; Flushesthe structure rigidity and the three-dimensional shape affects itsshape position precision.
(2) punching craft and molder structure type
Uses the different ramming craft, flushes a precision and the fixederror difference is really big. Except that the above piece gearexample showed, the essence flushes the craft and ordinary punching flushes a precision and the fixed error differs outside a magnitude,even if in ordinary punching center, uses the different gap punching, thefixed error difference very is also big. For example material thickt=1.5mm H62 brass punching, selects C <= the 40%t unilateral I kind ofsmall gap punching compared to select C <= 8%t (unilaterally) III kindof big gap punching, will flush a fixed error to enlarge 40% ~ 60%, theprecision at least will fall a level. Side in addition, whether thereis picks builds a row of type side, flushes a error to have far to bebigger than has builds a row of type to flush. Side not builds a rowof type to flush. Side not builds a row of type to flush a precisionto be lower than the IT12 level side, but most has builds a row oftype to flush a precision in IT11 between ~ IT9 level, material thickt > 4mm flushes, the size precision can lower some. Different die’s structure type, because is suitable the rammingmaterial to be thick and the manufacture precision difference, causesto flush a fixed error to have leaves. Compound die center, multi-locations continuous type compound die because flushes continuously toduplicate the localization to add on the pattern making error to bebigger, therefore it flushes a fixed error compound punching die to wantcompared to the single location Big 1 ~ 2 levels
(3) the craft of punching die’s manufacture
the main work of punching die namely are raised, the concave moldprocessing procedure, to operates on the specification not to behigh, can time form a more complex cavity. But its processing surfaceapproximately is thick > 0.03 ~ 0.05mm is the high temperatureablation remaining furcated austenite organization, degree ofhardness may reach as high as HRC67 ~ 70, has the micro crack, easilywhen punching appears broke the cutter or flaking. The Italian CorradaCorporation''s related memoir called "the line cut the processing contruction to have the disadvantageous influence to the superficialgold, in fact already changed the gold contruction. We must use theJin''gang stone powder to grind or the numerical control continual pathcoordinates rub truncate (cut to line) to make the precision work ". In recent years country and so on Switzerland and Japan, has conductedthe thorough research to the electrical finishing equipment and abigger improvement, makes function complete high accuracy NC and theCNC line cutter, the processing precision may reach ±0.005 ~ 0.001mm,even is smaller. The processing surface roughness Ra value can achieve0.4 mu m. According to the recent years to the domestic 12 productionlines cutter factory investigation and study, the domesticallyproduced line cutter processing precision different factory differentmodel line cutter might reach ±0.008 ~ ±0.005mm, generally all in±0.01mm or bigger somewhat, was individual also can achieve±0.005mm, the processing surface roughness Ra value was bigger than1.6μm. However, the electrical finishing ablation metal surface thus the change and the damage machined surface mental structure character can not change, only if with rubs truncates or other ways removes this harmful level. Therefore, merely uses electricity machining, including the spark cutting and the electricity perforation, achieves with difficulty punching, especially high accuracy, high life punching die to size precision and work components surface roughness Ra value request.
With precisely rubs truncates the law manufacture punching die, specially makes the high accuracy, the high life punching die, such as: Thin material small gap compound punching die, multi- locations continuous type compound die and so on, has the size precision high, the work component smachined surface roughness Ra value is small, the mold life higher characteristic. Its processing craft at present changed the electrical fire by the past ordinary engine bed rough machining spark cutting or the electricity puncher rough machining, finally precisely rubs truncates, also from takes shape rubs, optics curve rubs, the manual grid reference rubs gradually filters the continual path grid reference to rub and NC and the CNC continual path grid reference rubs, Processing coarseness may reach ±0.001 ~ 0.0005mm, the processing surface roughness Ra value may reach 0.1 ~ 0.025 mu m. Therefore, with this craft manufacture the die , regardless of the size precision, the work components surface roughness, all can satisfy die, each kind of compound request, the die is especially higher than the electrical finishing craft manufacture scale.
(4) gap size and degree of homogeneity
the flange and other sheet forming sgene rally all must first punching (fall material) the plate to launch the semi finished materials, after also has the forming to fall the material, the incision obtains the single end product to flush. Therefore punching the work, including is commonly used punching hole, the margin, cut side and so on, regarding each kind of sheet pressing partall is necessary. Therefore punching the gap to flushes a out form in chprecision to have the decisive influence. punching the gap small and is even, may cause punching the size gain high accuracy. Regarding drawability, is curving and so on mould, the gap greatly will decide increases flushes the oral area size error and the snapping back. The gapnon-uniformity can cause to flush a burr enlarges and incurs cutting edge the non-uniform attrition.
(5) ramming equipment elastic deformation In the ramming process
After the punch press load bearing can have the certain elastic deformation. Although this kind of distortion quantity according to flushes the pressure the size to change also to have the obvious directivity, but on the pressing part, mainly is to has the volume ramming archery target stamping, embosses, the equalization, the pressure is raised, the wave, flushes crowds, the shape, the flange, hits flatly, thinly changes draw ability and so on the craft work punching forming flushes, has the significant influence to its ramming aspect size precision
普通全鋼沖模的沖壓精度分析
板料沖壓件的精度準(zhǔn)確顯示出其沖模的沖壓精度。而任何沖件的線性尺寸精度與形位精度主要取決于沖模沖裁和立體成形沖壓件展開平毛坯的落料精度。因此,多工步復(fù)合沖壓的單工位復(fù)合模、多工位連續(xù)模的沖壓精度,在普通沖壓的眾多種類與不同結(jié)構(gòu)的沖模中,最具典型性和代表性。
沖模的沖壓精度分析
對(duì)沖模投產(chǎn)至失效報(bào)廢各個(gè)時(shí)期沖件的實(shí)際誤差分析,可以看出其增大的時(shí)期及趨向,從而分析其增大的因素。新沖模投產(chǎn)至第一次刃磨前沖制沖件的誤差即所謂的初始誤差;沖模經(jīng)過20次左右刃磨至失效報(bào)廢前沖制的沖件誤差稱之為常規(guī)誤差;而沖模失效報(bào)廢前沖制的最后一批合格沖件的允許最大誤差稱之為極限誤差。在現(xiàn)場(chǎng),確定沖模刃磨壽命的依據(jù)是沖件沖孔與落料的毛刺高度。由于任何成形件都具有沖裁作業(yè)(毛坯落料或沖孔),對(duì)于復(fù)合模尤為如此。所以,沖件毛刺高度的觸模檢查和測(cè)量并按企業(yè)標(biāo)準(zhǔn)或JB4129-85《沖壓件毛刺高度》對(duì)照檢測(cè)就顯得十分重要。
沖模的初始誤差通常是沖模整個(gè)壽命中沖件誤差最小的。其大小主要取決于沖模的制造精度與質(zhì)量及沖件尺寸、料厚以及間隙值大小與均勻度。沖模的制造精度及質(zhì)量又取決于制模工藝。對(duì)于料厚t≤1mm的中碳鋼復(fù)合沖裁模沖件,實(shí)驗(yàn)結(jié)果與生產(chǎn)實(shí)踐都證明,電火花線切割制造的沖模沖件毛刺高度比用成型磨或NC與CNC連續(xù)軌跡座標(biāo)磨即精密磨削工藝制造的沖模沖件要高25%~30%。這是因?yàn)楹笳卟粌H加工精度高,而且加工面粗糙度Ra值要比前者小一個(gè)數(shù)量級(jí),可達(dá)到0.025μm。因此,沖模的制造精度與質(zhì)量等因素決定了沖模的初始沖壓精度,也造就了沖件的初始誤差。
沖件的常規(guī)誤差是沖模經(jīng)第一次刃磨到最后一次刃磨后沖出最后一個(gè)合格沖件為止,沖件實(shí)際具有的誤差。隨著刃磨次數(shù)的增加,刃口的自然磨損而造成的尺寸增量逐漸加大,沖件的誤差也隨之加大。當(dāng)其誤差超過極限偏差時(shí),沖件就不合格,沖模也就失效報(bào)廢。///////沖件上孔與內(nèi)形因凸模磨損尺寸會(huì)逐漸變??;其外形落料尺寸會(huì)因凹模磨損而逐漸增大。所以,沖件上孔與內(nèi)形按單向正偏差標(biāo)允差并依接近或幾乎等于極限最大尺寸制模。同理,沖件外形落料按單向負(fù)偏差標(biāo)注允差并依接近或幾乎等于極限最小尺寸制模。這樣就使沖件的常規(guī)誤差范圍擴(kuò)大,沖??扇心ゴ螖?shù)增加,模具壽命提高。
沖件的極限誤差是具有極限偏差的沖件所具有的實(shí)際允許的最大尺寸誤差。這類沖件通常是在沖模失效報(bào)廢前沖制的最后一批合格沖件。
對(duì)各類沖模沖件誤差在沖模整個(gè)壽命中出現(xiàn)的波動(dòng)、增減趨向及規(guī)律等進(jìn)行全面分析便可發(fā)現(xiàn):沖件誤差的主導(dǎo)部分是不變的;因刃口或型腔的自然磨損而出現(xiàn)的誤差增量隨沖模刃磨沖數(shù)增加而使這部分誤差逐漸加大;還有部分誤差的增量是非常規(guī)的、不可預(yù)見的。所以,各類沖模沖件誤差是由因定誤差、漸增誤差、系統(tǒng)誤差及偶發(fā)誤差等幾部分綜合構(gòu)成。
1、固定誤差
新沖模在指定的沖壓設(shè)備上投入使用至失效報(bào)廢的整個(gè)(總)壽命過程中,其合格沖件誤差的主導(dǎo)部分固定不變即所謂固定誤差。其大小就是新沖模第一次刃磨前沖制的合格沖件的偏差,也即沖模的初始誤差,而此時(shí)的沖模具有初始沖壓精度。刃磨后的沖模,因其工作零件(凸、凹模)磨損而改變尺寸誤差,使沖件識(shí)差增量隨刃磨次數(shù)增加而逐漸加大,故沖模刃磨后的沖壓精度亦稱“刃磨精度”比其初始精度要低。沖模沖件的固定誤差取決于以下各要素:
(1)沖件的材料種類、結(jié)構(gòu)(形狀)尺寸及料厚
沖裁間隙的大小及其均勻度對(duì)沖裁件的尺寸精度有決定性的影響。不同沖裁工藝、不同材料種類與不等料厚,間隙相差懸殊,沖壓精度差異很大。同一種模數(shù)m=0.34的2mm的料厚、中心有孔的H62黃銅材料片齒輪復(fù)合模沖件,當(dāng)取間隙C=0.5%t(單邊),用復(fù)合精沖模沖制,沖件尺寸精度達(dá)到IT7級(jí),沖件平直無拱彎,沖切面垂直度可達(dá)89.5°,其表面粗糙Ra值為0.2μm;而用普通復(fù)合模沖制,間隙C=5%t(單邊),沖件初始誤差亦即沖模的初始沖壓精度為1T9級(jí),沖切面粗糙度Ra值為12.5μm,毛刺高度為0.10mm;還是這個(gè)沖件用連續(xù)模沖制,間隙C=7%t(單邊),初始沖件精度為IT11級(jí),沖切面更粗糙,甚至有肉眼可見的臺(tái)階。通常情況下,沖件材料及其厚度t是選取沖裁間隙的主要依據(jù)。一旦選定間隙就確定了沖件的平面尺寸的固定誤差的主體;沖件結(jié)構(gòu)剛度及立體形狀則影響其形位精度。
(2)沖壓工藝及沖模結(jié)構(gòu)類型
采用不同的沖壓工藝,沖件的精度及固定誤差相差甚大。除上述片齒輪實(shí)例說明,精沖工藝與普通沖裁的沖件精度與固定誤差相差一個(gè)數(shù)量級(jí)之外,即便在普通沖裁中,采用不同間隙沖裁,固定誤差相差也很大。例如料厚t=1.5mm的H62黃銅沖裁件,選用C≤40%t單邊Ⅰ類小間隙沖裁比選用C≤8%t(單邊)Ⅲ類大間隙沖裁,沖件固定誤差將加大40%~60%,精度至少降一級(jí)。此外,采有無搭邊排樣,沖件的誤差要遠(yuǎn)大于有搭邊排樣沖件。無搭邊排樣沖件。無搭邊排樣沖件的精度低于IT12級(jí),而多數(shù)有搭邊排樣的沖件精度在IT11~I(xiàn)T9級(jí)之間,料厚t>4mm的沖件,尺寸精度會(huì)更低一些。
不同沖模結(jié)構(gòu)類型,由于適用沖壓料厚及制造精度的差異,導(dǎo)致沖件的固定誤差有別。復(fù)合模中,多工位連續(xù)式復(fù)合模由于沖件連續(xù)重復(fù)定位加上制模誤差較大,故其沖件的固定誤差比單工位復(fù)合沖裁模要
大1~2級(jí)。
(3)沖模制造工藝
沖模主要工作零件即凸、凹模的加工程序,對(duì)操作上的技術(shù)要求不高,能夠一次成形較復(fù)雜的模腔。但其加工表面約厚>0.03~0.05mm為高溫?zé)g的殘余樹枝狀?yuàn)W氏體組織,硬度可高達(dá)HRC67~70,有顯微裂紋,容易在沖裁時(shí)出現(xiàn)崩刃或剝落。意大利Corrada公司的有關(guān)研究報(bào)告稱“線切割加工對(duì)表面金相結(jié)構(gòu)產(chǎn)生不利的影響,實(shí)際上已經(jīng)改變了金相結(jié)構(gòu)。我們必須用金剛石粉研磨或數(shù)控連續(xù)軌跡坐標(biāo)磨削(對(duì)線切割件)作精加工”。近年來瑞士和日本等國,對(duì)電加工設(shè)備進(jìn)行了深入的研究和較大的改進(jìn),制造出功能齊全的高精度NC和CNC線切割機(jī),加工精度可達(dá)±0.005~0.001mm,甚至更小。加工表面粗糙度Ra值能達(dá)到0.4μm。根據(jù)近年對(duì)國內(nèi)12家生產(chǎn)線切割機(jī)工廠的調(diào)研,國產(chǎn)線切割機(jī)加工精度各別廠家的各別型號(hào)線切割機(jī)可達(dá)±0.008~±0.005mm,一般都在±0.01mm或更大一些,個(gè)別也能達(dá)到±0.005mm,加工表面粗糙度Ra值均大于1.6μm。然而,電加工燒蝕金屬表面從而改變和損壞加工面金相結(jié)構(gòu)的特性不會(huì)改變,除非用磨削或其他加工法去除這一有害層。所以,僅僅用電加工法,包括電火花線切割與電穿孔,難以達(dá)到?jīng)_模,尤其高精度、高壽命沖模對(duì)尺寸精度與工作零件表面粗糙度Ra值要求。
用精密磨削法制造沖模,特別是制造高精度、高壽命沖模,諸如:薄料小間隙復(fù)合沖裁模、多工位連續(xù)式復(fù)合模等,具有尺寸精度高、工作零件加工面粗糙度Ra值小、模具壽命高等特點(diǎn)。其加工工藝目前已由過去的普通機(jī)床粗加工改為電火花線切割或電穿孔機(jī)粗加工,最后精密磨削,也由成型磨、光學(xué)曲線磨、手動(dòng)座標(biāo)磨逐步過濾到連續(xù)軌跡座標(biāo)磨及NC與CNC連續(xù)軌跡座標(biāo)磨,加工粗度可達(dá)±0.001~0.0005mm,加工表面粗糙度Ra值可達(dá)0.1~0.025μm。所以,用該工藝制造的沖模,無論尺寸精度、工作零件表面粗糙度,都能滿足沖模,尤其各種復(fù)合模的要求,比電加工工藝制造的沖模高一個(gè)檔次。
(4)間隙的大小與均勻度
拉深、彎曲、翻邊及其他板料成形件一般都要先沖裁(落料)出平板展開毛坯,也有成形后落料、切開得到單個(gè)成品沖件。故沖裁作業(yè),包括常用的沖孔、切口、切邊等,對(duì)于每種板料沖壓件都是必要的。所以沖裁間隙對(duì)沖件的外廓尺寸精度有決定性的影響。沖裁間隙小而均勻,可使沖裁尺寸獲取更高精度。對(duì)于拉深、彎曲等成形模,間隙大定將增大沖件口部尺寸誤差及回彈。間隙不均勻會(huì)使沖件毛刺加大并招致刃口的不均勻磨損。
(5)沖壓設(shè)備的彈性變形
在沖壓過程中,沖床承載后會(huì)產(chǎn)生一定的彈性變形。雖然這種變形量依沖壓力的大小變化且具有明顯的方向性,但就沖壓件,主要是對(duì)具有體積沖壓性質(zhì)的壓印、壓花、校平、壓凸、起波、沖擠、鐓形、翻邊、鐓粗、打扁、變薄拉深等工藝作業(yè)沖制成形的沖件,對(duì)其沖壓方面的尺寸精度有重大影響。
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