F形鋼板沖壓工藝設(shè)計【E型墊片墊板】【落料沖孔復(fù)合?!俊菊f明書+CAD】
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學(xué)校:xxxxx
學(xué)院:機(jī)電工程學(xué)院
班級:xx
組別:xx
學(xué)號:xxxx
姓名:xx
指導(dǎo)老師:xxx
F形鋼板沖壓工藝及夾具設(shè)計
F形鋼板沖壓工藝及夾具設(shè)計
如圖1所示零件:F形鋼板
生產(chǎn)批量:中小批量
材料:08F 料厚t=1.2mm
公差按IT14級制造
本零件為落料沖孔模
設(shè)計該零件的沖壓工藝與模具 。
圖1 鋼板
設(shè)計該零件的沖壓工藝與模具
(一) 沖壓工藝分析設(shè)計
沖裁件的工藝性是指從沖壓工藝方面來衡量設(shè)計是否合理。一般的講,在滿足工件使用要求的條件下,能以最簡單最經(jīng)濟(jì)的方法將工件沖制出來,就說明該件的沖壓工藝性好,否則,該件的工藝性就差。當(dāng)然工藝性的好壞是相對的,它直接受到工廠的沖壓技術(shù)水平和設(shè)備條件等因素的影響。以上要求是確定沖壓件的結(jié)構(gòu),形狀,尺寸等對沖裁件工藝的實(shí)應(yīng)性的主要因素。根據(jù)這一要求對該零件進(jìn)行工藝分析。
零件尺寸部分公差已經(jīng)給出,其余未標(biāo)注公差,屬自由尺寸,可按IT14級確定工件尺寸的公差,經(jīng)查公差表,各尺寸公差為:500-0.62、24.70-0.52、70-0.36、6.50-0.36、10±0.18、150+0.43以根據(jù)圖紙要求進(jìn)行設(shè)計并畫圖,利用普通沖裁方式可達(dá)到圖樣要求。
材料為08F鋼板是優(yōu)質(zhì)碳素結(jié)構(gòu)鋼,具有良好的可沖壓性能。材料的厚度為1.2mm。由于該件外形簡單,形狀規(guī)則,適于落料沖孔加工。
(二) 確定工藝方案及模具結(jié)構(gòu)形式
確定方案就是確定沖壓件的工藝路線,主要包括沖壓工序數(shù),工序的組合和順序等。確定合理的沖裁工藝方案應(yīng)在不同的工藝分析進(jìn)行全面的分析與研究,比較其綜合的經(jīng)濟(jì)技術(shù)效果,選擇一個合理的沖壓工藝方案。
經(jīng)分析,該零件屬于中小批量生產(chǎn),工藝性較好,沖壓件尺寸精度不高,形狀簡單。根據(jù)現(xiàn)有沖模制造條件與沖壓設(shè)備,采用沖裁沖孔復(fù)合模,模具制造周期短,價格低廉,工人操作安全,方便可靠。
(三) 模具設(shè)計計算
1.排樣
因為矩形邊長L=50mm 查表1可知
兩工件間按矩形取搭邊值a=1.8,工件與邊緣搭邊值a1=1.5.
條料寬度按相應(yīng)的公式計算:
B=(D+2a+δ)- δ 查表 2 ⊿=0.5 C=0.2
B=(50+2×2+0.5)0-0.5
B=54.50-0.5 mm
表1 搭邊值和側(cè)邊值的數(shù)值
材料厚度t(mm)
圓件及r>2t圓角
矩形邊長l≤50
矩形邊長l>50或圓角 r≤2
工件間a1
側(cè)邊a
工件間a
側(cè)邊a1
工件間a1
側(cè)邊a
0.25以下
1.8
2.0
2.2
2.5
2.8
3.0
0.25~0.5
1.2
1.5
1.8
2.0
2.2
2.5
0.5~0.8
1.0
1.2
1.5
1.8
1.8
2.0
0.8~1.2
0.8
1.0
1.2
1.5
1.5
1.8
1.2~1.5
1.0
1.2
1.5
1.8
1.9
2.0
1.6~2.0
1.2
1.5
2.0
2.2
2.0
2.2
表2 剪裁下的下偏差△(mm)
條料厚度t(mm)
條料寬度b(mm)
≤50
>50~100
>100~200
>200
≤1
0.5
0.5
0.7
1.0
>1~3
0.5
1.0
1.0
1.0
>3~4
1.0
1.0
1.0
1.5
>4~6
1.0
1.0
1.0
2.0
根據(jù)上述數(shù)據(jù)可知圖形搭邊值和條料寬度,如圖2可示:
圖2 排樣圖
2.計算沖裁力
若采用平刃沖裁模,其沖裁力Pp按下式計算:
P—沖裁力;
L—沖裁周邊長度;
t—材料厚度;
τ—材料抗剪強(qiáng)度;
K—系數(shù);
系數(shù)K是考慮到實(shí)際生產(chǎn)中,模具間隙值的波動和不均勻,刃口磨損、板料力學(xué)性能和厚度波動等原因的影響而給出修正系數(shù),一般取K=1.3。
L=50+50+10×4+24.7×2=189.4 mm
查τ>=210-400 取τ=300
Pp= KLtτ
=1.3×(50+50+10×4+24.7×2)×1.2×300
=88639.2N
3 計算總沖壓力:
卸料力、頂件力、推料力的計算
在沖裁結(jié)束時,由于材料的彈性回復(fù)(包括徑向回復(fù)和彈性翹曲回復(fù))及摩擦的存在,將使沖落的材料梗塞在凹模內(nèi),而沖裁剩下的材料則緊箍在凸模上。為使沖裁工作繼續(xù)進(jìn)行,必須將緊箍在凸模上的料卸下,將梗塞在凹模內(nèi)的材料推出。從凸模上卸下箍著的料稱卸料力;逆沖裁方向?qū)⒘蠌陌寄?nèi)頂出所需要的力稱為頂件力;從凹模內(nèi)向下推出制件或廢料所需的力,稱為推料力。一般按以下公式計算:
卸料力 P X=KXpP
頂件力 PD=KDPP
推料力 PQ=nK1Pp
式中,F(xiàn)P——沖裁力,N;
KX——卸料力系數(shù),可查表;
KD——頂件力系數(shù),可查表;
K1——推料力系數(shù),可查表;
n——梗塞在凹模內(nèi)的制件或廢料數(shù)量,n=h/t h為凹模直刃高度,t為板厚;
KX=0.04 KD=0.06 K1=0.05
卸料力計算:P X=KXPP
=0.04×88639.2
=3545.6N
頂件力計算:PD=KDPP
=0.06×88639.2
=5318.4N
推料力計算:PQ=nK1Pp
=3×0.05×88639.2
=13295.9N
如表3.1
材料種類
板料厚度/mm
Kx
K1
KD
鋼
~0.1
>0.1~0.5
>0.5~2.5
>2.5~6.5
>6.5
0.06~0.075
0.045~0.055
0.04~0.05
~0.03~0.04
0.02~0.03
0.1
0.065
0.050
0.045
0.025
0.14
0.08
0.06
0.05
0.03
黃銅、紫銅
0.02~0.06
0.03~0.09
鋁、鋁合金
0.025~0.08
0.03~0.07
所以總沖壓力: P總= P X+ PD+ PQ
=3545.6N+5318.4N+13295.9N
=22159.9N
4 確定壓力中心:
(1) 沖孔壓力中心:
X01=25
Y01=(L1y1+L2y2+……Lnyn )/(L1+L2+…+Ln)
=11.49mm
(2)落料壓力中心:
X02=25
Y02=(L1y1+L2y2+……Lnyn )/(L1+L2+…+Ln)
=12.35mm
(3)總壓力中心:
X0=25 mm Y0=11.64 mm
5模具刃口尺寸的計算:
(1) 凹模結(jié)構(gòu)設(shè)計
考慮本成品零件的結(jié)構(gòu)形狀,本凹模采用矩形局凹模,其材料和凸模一樣為
10TA,熱處理硬度為58-62HRC內(nèi)形尺寸即半成品的外形.
凹模厚度 H=Kb(>=15mm)
凹模壁厚 C=(1.5~2)H(>=30~40mm)
式中,b為沖裁件的最大外型尺寸;K是考慮板厚度的影響系數(shù)。查表可知
K=0.35
凹模厚度H=Kb=0.35×54=18.9 mm
凹模壁厚C=(1.5~2)H=2H=37.8 mm
凹模長度L的確定
W1=2C=75.6;工件b=37.8
L=b+2W1=37.8+ W1=113.4mm=115 mm
凹模寬度B的確定
B= 2C+工件寬
=75.6+24.7
=100.3 mm=100 mm
L×B×H=115×100×18.9 mm
沖孔凹模設(shè)計
沖孔孔徑D=φ3.2 mm
(2) 凸模長度L1的確定
落料凸模長度計算為:
L1=h1+h2+t+Y
其中 導(dǎo)料板厚h1=25;卸料板厚h2=20;板料厚度t=1.2; 凸模修磨量Y=20則
L1=h1+h2+t+Y
=25+20+1.2+20
=66.2 mm
鑲塊式凸模沖孔桿長度計算為
L2= L1+h3+t
其中L1為落料凸模長度,h3為凸模桿凸出長度,t為板厚。
L2= L1+h3+t
=66.2+3+1.2
=70.4 mm
6計算凸、凹模的工作部分的尺寸
在沖模刃尺寸計算時需要注意:在計算工件外形落料時,應(yīng)以凹模為基準(zhǔn),凸模尺寸按相應(yīng)的凹模實(shí)際尺寸配制。保證雙面間隙為0.096~0.120 mm。
A類: Aj=(Amax-X△)0δ
B類: Bj=(Bmin+X△)0-δ
式中,Aj、Bj——基準(zhǔn)件尺寸,單位均為mm。
Amax、Bmin——相應(yīng)的工件極限尺寸,單位均為mm。
△——工件公差,單位均為mm。
δ——基準(zhǔn)件制造偏差,單位均為mm。當(dāng)刃口尺寸公差標(biāo)注形式為+δ
(-δ)時,δ=△/4,當(dāng)標(biāo)注形式為+-δ時,δ=△/8.
第一類尺寸A1、A2、A3、A4.由表1查表得:
X1、X2=0.5 X3、X4=0.75
A1=(50-0.5×0.62)00.62/4 =49.69 0+0.155mm
A2=(24.7-0.5×0.52)00.52/4=24.4400.13 mm
A3=(7-0.75×0.36)00.36/4=6.7300.09 mm
A4=(6.5-0.75×0.36)00.36/4=6.2300.09 mm
第二類尺寸B。查表1得,X=0.5 有公式得:
B=(15+0.5×0.43)-0.43/40=15.215-0.1080 mm
第三類尺寸C。查表1得,X=0.5 有公式得:
C=(9.82+0.5×0.36) ±0.36/8=10±0.045 mm
沖孔時應(yīng)以凸模為基準(zhǔn)件來配作凹模。此工件的尺寸公差有查表可知:3.2+0.080 mm
有沖壓工藝學(xué)教材表:Zmax=0.120 mm, Zmin=0.096 mm
Zmax- Zmin=0.024 mm
沖孔部分: δp=0.020 mm, δd=0.020 mm
X=0.5
dp=(d+X△)- δ0=(3.2+0.5×0.08) – 0.020=3.24 – 0.020 mm
dd=(dp+ Zmin)0+δd =(3.24+0.096) 0+0.02 mm=3.3360+0.02 mm
表10 系數(shù)X
料厚t(mm)
非圓形
圓形
1
0.75
0.5
0.75
0.5
工件公差△/mm
1
1~2
2~4
>4
<0.16
<0.20
<0.24
<0.30
0.17~0.35
0.21~0.41
0.25~0.49
0.31~0.59
≥0.36
≥0.42
≥0.50
≥0.60
<0.16
<0.20
<0.24
<0.30
≥0.16
≥0.20
≥0.24
≥0.30
(四)沖裁工藝方案的確定
1. 沖裁工序的組合
(1)生產(chǎn)批量:中批和大批量生產(chǎn)采用復(fù)合沖裁
(2)工件尺寸公差等級:復(fù)合沖裁所得到的工件尺寸公差等級高,因為它避免了多次沖壓的定位誤差,并且在沖裁過程中可以進(jìn)行壓料,工件較平整。
(3)對工件尺寸、形狀的適應(yīng)性:工件的尺寸較小時,考慮到單工序上料不方便和生產(chǎn)效率低,常采用復(fù)合沖裁。
(4)模具制造、安裝調(diào)整和成本:對復(fù)雜形狀的工件,采用復(fù)合沖裁較為適合,因模具制造、安裝調(diào)整較易,成本較低。
(5)操作方便與安全:復(fù)合沖裁處件或清除廢料較困難,工件安全性較差。
2.沖裁順序安排
根據(jù)圖形安排,先進(jìn)行沖孔,沖孔結(jié)束后再進(jìn)行落料,這樣能保證精度。
(五)凸模強(qiáng)度的校核
??? 在一般情況下,凸模的強(qiáng)度和剛度是足夠的,無須進(jìn)行強(qiáng)度校核。但對特別細(xì)長的凸模或凸模的截面尺寸很小而沖裁的板料厚度較厚時,則必須進(jìn)行承壓能力和抗縱彎曲能力的校核。其目的是檢查其凸模的危險斷面尺寸和自由長度是否滿足要求,以防止凸??v向失穩(wěn)和折斷。強(qiáng)度的校核的目的主要是檢查其高度是否足夠,若高度不夠,將會產(chǎn)生彎曲變形以至損壞
查《實(shí)用模具設(shè)計與制造手冊》[3]表2—94凹模的強(qiáng)度校核公式
σW=1.5P/h×h (3.7)
hmin= 1.5p/[σW]
其中為沖裁力
P=Ltτ=π357×1.5×300=50444.1N Pp= KLtτ
=1.3×(50+50+10×4+24.7×2)×1.2×300
=88639.2N
hmin==1.5×88639.2N=60mm
取h=65mm
所以凸模強(qiáng)度符合強(qiáng)度要求
凹模板上螺釘孔
的確定
查〈〈冷沖模具設(shè)計與指導(dǎo)〉〉表1—26 ,可以用M10的緊固螺釘,材料為45鋼許用負(fù)載為3100N
查表可得
a1=12.5d=10mm
a2=1.5d=12mm
(六) 模具模架選擇
(1)沖壓設(shè)備的選用
壓力機(jī)對模具壽命的影響也不容被忽視。壓力機(jī)在不加載狀態(tài)下的精度稱為靜精度,加載狀態(tài)下的精度稱為動精度。
當(dāng)壓力機(jī)的動精度不好時,就等于喲暖和精度不好的壓力機(jī)進(jìn)行沖壓加
工。由于測量動精度很困難,目前還沒有壓力機(jī)動精度的標(biāo)準(zhǔn),生產(chǎn)廠家
也只保證壓力機(jī)的靜精度。因此壓力機(jī)的動精度一般只能根據(jù)其靜精度的好壞、框架結(jié)構(gòu)形式和尺寸以及對壓力機(jī)生產(chǎn)廠家的信任程度來推斷。
根據(jù)以上原因和總的沖裁力必須小于或等于壓力機(jī)的公稱壓力,故選壓力機(jī)型號
故選壓力機(jī)型號為開式壓力機(jī)其技術(shù)規(guī)格如下:
公稱壓力 40KN
滑塊行程 40mm
滑塊行程次數(shù) 6
最大的封閉高度為260mm
閉合高度調(diào)節(jié)量為35 mm
工作臺尺寸前后180mm
左右280mm
模柄孔尺寸(直徑x深度) Φ30×50
(2) 模柄的選用
通過查找手冊確定選用壓入式模柄
模柄材料:Q235-1F GB700
直徑d=32mm 高度L=80mm的A型壓入式模柄
模柄A 32×80 JB/T 7646.1
(3)模具的閉合高度的計算
沖模的閉合高度是指滑塊在下死點(diǎn)即模具在最低工作位置時,上模座上平面與下模座下平面之間的距離H。沖模的閉合高度必須與壓力機(jī)的裝模高度相適應(yīng)。壓機(jī)的裝模高度 是指滑塊在下死點(diǎn)位置時,滑塊下端面至墊板上平面間的距離。當(dāng)連桿調(diào)至最短時為壓機(jī)的最大裝模高度Hmax;連桿調(diào)至最長時為為最小裝模高度Hmin。
沖模的閉合高度H應(yīng)介于壓機(jī)的最大裝模高度Hmax之間,其關(guān)系為:
Hmax-5mm≥H≥Hmin+10mm 255>H>220
如果沖模的閉合高度大于壓機(jī)最大裝模高度時,沖不能在該壓力機(jī)上使用。反之小于壓力機(jī)最小裝模高度時,可加經(jīng)過磨平的墊板。
沖模的其它外形結(jié)構(gòu)尺寸也必須和壓力機(jī)相適應(yīng),如模具外形輪廓平面尺寸與壓力機(jī)墊板、滑塊底面尺寸,模柄與模柄孔尺寸,下模緩沖器平面尺寸與壓力機(jī)墊板孔尺寸等都必須相適應(yīng),以便模具能正確安裝和正常使用。
(4)根據(jù)凹模寬度B、長度L、厚度H,凸模長度L1、導(dǎo)料板厚、卸料板厚、板料厚度、凸模修磨量等數(shù)據(jù)查表得到模具模架的尺寸。查表可得數(shù)據(jù)如下
1、上下模座 GB/T2856.3 250×200×50
2、導(dǎo)柱 GB/T2861.4 32×215
3、導(dǎo)套 GB/T2861.8 32×150×48
4、螺釘 DB/T70.1 M6×43
5、模具閉合高度 H=230mm
(5) 推桿的選材,熱處理工藝方案
根據(jù)《冷沖壓模具設(shè)計手冊》 [2]一般用途的推桿的 材料選擇45鋼。它是一種優(yōu)質(zhì)碳素鋼。含磷比較少,非金屬雜質(zhì)比較少。鋼的品質(zhì)較高。它須調(diào)質(zhì)處理后使用,調(diào)質(zhì)處理后具有良好的綜合力學(xué)性能,即具有較高的的刃性和塑性,焊接性能也好。固采用此鋼比較好。
(6) 推桿與推板的設(shè)計
為了便于裝在凹模內(nèi),本副模具采用剛性推件裝置。
同時采用圓柱形推板,推板的大直徑大約設(shè)計為6mm,小直徑大約設(shè)計為3.2mm推板的長度大約為152mm
(7) 卸料板的設(shè)計
一般卸料板材料為45號鋼,它是一種優(yōu)質(zhì)碳素鋼,卸料板的形狀設(shè)計為長方形,其工作部分的尺寸由沖落料部分的凸凹模來決定,并且與凸凹模保持1~2mm的間隙。
(8) 確定裝配基準(zhǔn)
1、 落料,沖孔應(yīng)以沖材凸凹模為裝配基準(zhǔn)件。
首先確定凸凹模在模架中的位置,安裝凸凹模組件,確定凸凹組件在下模座的位置,然后用平行板將凸凹模和下模座夾緊。
沖裁模具材料的選?。?
可查《冷沖壓模具設(shè)計指導(dǎo)》表8-8和8-9:
凸模的材料為T10A,凹模的材料為T10A,熱處理硬度為58-62HRC,墊板、凸模固定板、凹模固定板的材料的45號鋼,熱處理硬度為HRC43-48。
沖裁模的常用配合:
2、 H7/h6的間隙定位配合,導(dǎo)柱和導(dǎo)套的配合。
3、 H7/r6的過度配合,用于較高的定位,凸模與固定板的配合,導(dǎo)套與模座,導(dǎo)套與固定板,模柄與模座的配合。
4、 H7/m6的過度配合,能以最好的定位精度滿足零件的剛性和定位要求,凸模的固定導(dǎo)套與模座的固定、導(dǎo)柱與固定板的固定。
實(shí)驗小節(jié)
隨著社會的發(fā)展,機(jī)械行業(yè)的模具專業(yè)在我國現(xiàn)代工業(yè)發(fā)展中成為一個越來越重要的分支。模具滲透著整個社會。不管在那個行業(yè),都有模具的存在。日常生活中輕重工業(yè),都離不開模具生產(chǎn),模具就是為了得到所需要的產(chǎn)品。要什么樣的產(chǎn)品,就可以生產(chǎn)什么樣的模具,如(塑料模具 、冷沖壓模具、壓鑄模、橡膠模 )。而目前形勢的需要,產(chǎn)品更新?lián)Q代更快更易,所以模具行業(yè)的發(fā)展空間很大,有待我們?nèi)ヅ?,去探索?
模具生產(chǎn)過程是一個循序漸進(jìn)的過程,生產(chǎn)模具過程中可能用到的的機(jī)器有很多種類,如(電火花成型機(jī)、數(shù)控線切割、車床、銑床、刨床、磨床、鏜床等)。
三年的學(xué)習(xí),我對模具設(shè)計與制造有了深刻的認(rèn)識。此次單獨(dú)設(shè)計一個模具,讓我了解了很多的模具結(jié)構(gòu)、模具加工工藝、模具的用途。并且學(xué)到不少的書本上沒有的知識,就拿塑料模來說,對于影響模具壽命的因素,主要是模具的加工精度和材料的剛度,還有模具的材料,模具生產(chǎn)批量,模具結(jié)構(gòu)等。影響模具的產(chǎn)品質(zhì)量的主要因素也是模具的制造精度。。
通過這次課程設(shè)計,我從理論和實(shí)踐上又更進(jìn)一步的加深。模具結(jié)構(gòu)設(shè)計的好壞直接影響產(chǎn)品質(zhì)量和經(jīng)濟(jì)。中國面臨世界的挑戰(zhàn),在模具行業(yè)這方面,我希望日后能在模具這一行有所貢獻(xiàn)。
感謝我的導(dǎo)師田浩彬老師,她嚴(yán)謹(jǐn)細(xì)致、一絲不茍的作風(fēng)一直是我工作、學(xué)習(xí)中的榜樣;他們循循善誘的教導(dǎo)和不拘一格的思路給予我無盡的啟迪。這次的課程設(shè)計讓我又更加深了模具設(shè)計各方面知識。
參考文獻(xiàn)
[1] 《冷沖模設(shè)計》———丁松聚主編-——北京機(jī)械工業(yè)出版社
[2] 《冷沖壓模具設(shè)計手冊》——— 丁松聚主編———機(jī)械工業(yè)出版社
[3] 《沖壓工藝與模具設(shè)計》———成虹主編———北京高等教育出版社
[4] 《沖壓模具設(shè)計及實(shí)例精解》———宛強(qiáng)主編———北京化學(xué)工業(yè)出版社
[5] 《畫法幾何及工程制圖———朱輝主編———上??茖W(xué)技術(shù)出版社
外文翻譯
專 業(yè) 名 稱 機(jī)械設(shè)計制造及其自動化
班 級 學(xué) 號 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
對沖模投產(chǎn)至失效報廢各個時期沖件的實(shí)際誤差分析,可以看出其增大的時期及趨向,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廢前沖制的沖件誤差稱之為常規(guī)誤差;而沖模失效報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,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),對于復(fù)合模尤為如此。所以,沖件毛刺高度的觸模檢查和測量并按企業(yè)標(biāo)準(zhǔn)或JB4129-85《沖壓件毛刺高度》對照檢測就顯得十分重要。
沖模的初始誤差通常是沖模整個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。對于料厚t≤1mm的中碳鋼復(fù)合沖裁模沖件,實(shí)驗結(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%。這是因為后者不僅加工精度高,而且加工面粗糙度Ra值要比前者小一個數(shù)量級,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,沖件就不合格,沖模也就失效報廢。///////沖件上孔與內(nèi)形因凸模磨損尺寸會逐漸變??;其外形落料尺寸會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廢前沖制的最后一批合格沖件。
對各類沖模沖件誤差在沖模整個壽命中出現(xiàn)的波動、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廢的整個(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,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,沖切面粗糙度Ra值為12.5μm,毛刺高度為0.10mm;還是這個沖件用連續(xù)模沖制,間隙C=7%t(單邊),初始沖件精度為IT11級,沖切面更粗糙,甚至有肉眼可見的臺階。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數(shù)量級之外,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。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,而多數(shù)有搭邊排樣的沖件精度在IT11~I(xiàn)T9級之間,料厚t>4mm的沖件,尺寸精度會更低一些。
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。
(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的殘余樹枝狀奧氏體組織,硬度可高達(dá)HRC67~70,有顯微裂紋,容易在沖裁時出現(xiàn)崩刃或剝落。意大利Corrada公司的有關(guān)研究報告稱“線切割加工對表面金相結(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(對線切割件)作精加工”。近年來瑞士和日本等國,對電加工設(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線切割機(jī)可達(dá)±0.008~±0.005mm,一般都在±0.01mm或更大一些,個別也能達(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、切開得到單個成品沖件。故沖裁作業(yè),包括常用的沖孔、切口、切邊等,對于每種板料沖壓件都是必要的。所以沖裁間隙對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,對其沖壓方面的尺寸精度有重大影響。
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