墊圈產(chǎn)品沖裁模設(shè)計(jì)【沖壓模具設(shè)計(jì)】【說明書+CAD+STP三維】
墊圈產(chǎn)品沖裁模設(shè)計(jì)【沖壓模具設(shè)計(jì)】【說明書+CAD+STP三維】,沖壓模具設(shè)計(jì),說明書+CAD+STP三維,墊圈產(chǎn)品沖裁模設(shè)計(jì)【沖壓模具設(shè)計(jì)】【說明書+CAD+STP三維】,墊圈,產(chǎn)品,沖裁模,設(shè)計(jì),沖壓,模具設(shè)計(jì),說明書,仿單,cad,stp,三維
摘要
本次設(shè)計(jì)了墊圈的復(fù)合沖壓模具。首先要對(duì)沖壓模具進(jìn)行工藝分析，經(jīng)過工藝分析和對(duì)比確定模具架及壓力機(jī)，確定壓力機(jī)的型號(hào)。再分析對(duì)沖壓件加工的模具適用類型選擇所需設(shè)計(jì)的模具。得出將設(shè)計(jì)的模具類型后將模具的各工作零部件設(shè)計(jì)過程表達(dá)出來。
在說明書中第一部分，主要敘述了沖壓模具的發(fā)展?fàn)顩r，說明了沖壓模具的重要性與本次設(shè)計(jì)的意義，對(duì)沖壓件的工藝分析，工藝方案的確定。通過，對(duì)零件排樣圖的設(shè)計(jì)，完成了材料利用率的計(jì)算。再進(jìn)行沖裁工藝力的計(jì)算和沖裁模工作部分的設(shè)計(jì)計(jì)算。最后對(duì)主要零部件的設(shè)計(jì)和標(biāo)準(zhǔn)件的選擇，為本次設(shè)計(jì)模具的繪制和模具的成形提供依據(jù)，以及為裝配圖各尺寸提供依據(jù)。通過前面的設(shè)計(jì)方案畫出模具各零件圖和裝配圖。
關(guān)鍵字：沖壓；工藝:模具結(jié)構(gòu)
Abstract
A molding tool for designing a set ofly hurtling bore, falling anticipating.Want to proceed the craft analysis to the washer first, analyze through craft with contrast certain molding tool a model number for and pressure machine, making sure pressure machine.Analyze again to wash to press a molding tool for processing apply the type the choice a molding tool for needing design.Get a molding tool for will designing type empress expresses out each work zero parts design process of the molding tool.
In text file the first part, described to wash the development condition that press the molding tool primarily, explain to wash the importance that press the molding tool and the meaning of this design, to craft that washing and pressing the piece analyzes, the craft project really settles.Pass, line up the design of the kind diagram to the spare parts, complete the calculation of the material utilization.Proceed again the calculation that wash cut the craft dint with wash to cut mold work part of designs calculation.Finally to the design of the main the parts of zero with the choice of the standard piece, draw for this design molding tool to take shape the offering with the molding tool according to, and for assemble each size of diagram offering according to.The design project passing before draws an each spare parts of molding tool diagram with assemble the diagram.
Keyword:Wash to press;Fall to anticipate to hurtle the bore;Molding tool construction
目錄
摘要 1
Abstract 2
第1章 零件的分析 5
1.1 零件的工藝性分析 5
1.1.1 設(shè)計(jì)題目?jī)?nèi)容 5
1.1.2 材料的性能 5
1.1.3 沖壓成型工藝分析 6
1.2 工藝方案分析 6
1.2.1 方案種類 6
1.2.2 方案比較 6
第2章 沖壓工藝計(jì)算 7
2.1 落料力的計(jì)算 7
2.2 沖孔力的計(jì)算 8
2.3 卸料力的計(jì)算 9
2.4 推件力的計(jì)算 9
2.5 頂件力的計(jì)算 9
2.6 選擇壓力機(jī) 9
2.7 壓力中心計(jì)算 11
第3章 排樣設(shè)計(jì)計(jì)算 12
第4章 工作零件的設(shè)計(jì) 13
4.1 模具間隙的確定 13
4.2 沖孔刃口尺寸計(jì)算 16
4.3 落料刃口尺寸計(jì)算 16
第5章 輔助結(jié)構(gòu)零件的設(shè)計(jì)及選用 17
5.1 模具總體結(jié)構(gòu)設(shè)計(jì) 17
5.2 凸凹模固定板 17
5.3凸模固定板 17
5.4 墊板 18
5.5 卸料板 18
5.6 操作與定位方式 19
第6章 模具的裝配圖的設(shè)計(jì) 20
6.1 零件的技術(shù)要求 20
6.2 裝配技術(shù)要求 20
6.3 模具安裝要求 21
6.4 復(fù)合模的調(diào)試要求 21
6.5 主要組件的裝配 21
第8章 模具工作過程 23
結(jié)論與展望 24
致謝 25
參考文獻(xiàn) 26
第1章 零件的分析
1.1 零件的工藝性分析
1.1.1 設(shè)計(jì)題目?jī)?nèi)容
圖2-1 工件圖
原始資料：如圖2-1所示
零件材料：為紫銅；厚度：為0.8mm；生產(chǎn)批量：屬于大批量生產(chǎn)
根據(jù)圖1可以知道，零件為落料沖孔墊圈。根據(jù)GB/T15055-2007f沖壓件未注公差尺寸極限偏差可查得，分別是落料，沖孔。這2個(gè)工序可以在一副模具上完成，也可以在兩、三或者四副模具上完成，其需要在幾副上完成主要根據(jù)零件的外型來確定
1.1.2 材料的性能
紫銅并會(huì)隨著材質(zhì)的厚度的增加而使其屈服值減小。保證機(jī)械性能,不保證化學(xué)成分,不能熱處理,機(jī)械性能較低,比較常用,價(jià)格便宜。
1.1.3 沖壓成型工藝分析
此工件為紫銅，厚度為0.8mm, 具有良好的沖壓性能，適合沖裁，具有良好的沖壓工藝性。主要工藝難點(diǎn)在于兩個(gè)精度要求，及其零件的形狀不規(guī)則，在大批量的生產(chǎn)條件下，要保證生產(chǎn)效率。選取合理的模具類型、結(jié)構(gòu)，采用最經(jīng)濟(jì)的制模工藝。因?yàn)樵摿慵寺淞?、沖孔這2道工序
1.2 工藝方案分析
1.2.1 方案種類
根據(jù)制件工藝性分析，要加工此零件，分析出以下兩種方案。
方案一：落料,沖孔單工序,共2道工序
方案二：落料,沖孔,復(fù)合沖裁模方案一次性實(shí)現(xiàn)沖孔
1.2.2 方案比較
方案1屬于單工序模。模具結(jié)構(gòu)簡(jiǎn)單，制造方便，但需要2道工序，再加之此制件生產(chǎn)批量大，尺寸較小，這種方案生產(chǎn)率低，一般不宜采用。
方案2為復(fù)合沖裁模，在同一部位同時(shí)完成了零件的生產(chǎn)，對(duì)于這種大批量生產(chǎn)零件，大大的提高了生產(chǎn)效率。故選用方案二。
第2章 沖壓工藝計(jì)算
由于該零件的生產(chǎn)過程要經(jīng)過落料，沖孔2道工序，且是落料沖孔其模具類型選擇復(fù)合模形式。所以在選設(shè)備的時(shí)候要先計(jì)算哪個(gè)工序需要的力大些，其次還需考慮最大的力是否在壓力機(jī)安全范圍內(nèi)等等，以下是壓力機(jī)選擇要考慮的基本因素：
1 沖壓設(shè)備的類型和工作形式是否使用于應(yīng)完成的的工序；是否適合安全生產(chǎn)和環(huán)保的要求；
2 沖壓設(shè)備的壓力和功率是否滿足應(yīng)完成工序的需要；
3 沖壓設(shè)備的裝模高度，臺(tái)面尺寸，行程等是否適合完成工序所用的模具；
4 沖壓設(shè)備的行程次數(shù)是否滿足生產(chǎn)率的要求等。
2.1 落料力的計(jì)算
1 沖裁力的計(jì)算 =Ltτ
其中 --------沖裁力，單位為N；
t---------材料厚度，單位為mm；
τ---------材料抗剪強(qiáng)度，單位為MPa；對(duì)紫銅 取350MPa；
L---------沖裁周長(zhǎng)，單位為mm。
考慮到模具刃口的磨損，凸凹模間隙的波動(dòng)，材料機(jī)械性能的變化，材料厚度的偏差等因素，實(shí)際所需沖裁力還必須增加30%，即 F=1.3=1.3Ltτ
F=1.3=1.3Ltτ=1.3x61.77x0.8x350=22.48KN
2.2 沖孔力的計(jì)算
沖裁力 =Ltτ
其中--------沖裁力，單位為N；
t---------材料厚度，單位為mm；
τ---------材料抗剪強(qiáng)度，單位為MPa；對(duì)紫銅取350MPa；
L---------沖裁周長(zhǎng)，單位為mm。
考慮到模具刃口的磨損，凸凹模間隙的波動(dòng)，材料機(jī)械性能的變化，材料厚度的偏差等因素，實(shí)際所需沖裁力還必須增加30%，即
F=1.3=1.3Ltτ=1.3x20.42x350*0.8=7.43KN
2.3 卸料力的計(jì)算
由[2]得卸料力的計(jì)算公式
F卸料=K卸料F落料 （3.3）
式中： K卸料—卸料力系數(shù)，查表3.1。
F卸料=K卸料F落料
=0.034×22.48
=0.76（kN）
2.4 推件力的計(jì)算
由[2]中推件力的計(jì)算公式
F推件=nK推件F沖孔（3.4）
式中： K推件—推件力系數(shù)，查表3.1。
n—同時(shí)梗塞在凹模內(nèi)的工件數(shù)（廢料數(shù)）；
F推件=nK推件F沖孔
=0.045×7.43
=0.334（kN）
2.5 頂件力的計(jì)算
由[2]中頂件力的計(jì)算公式
F頂件=K頂件F落料 （3.5）
式中： K頂件—頂件力系數(shù)，查表3.1。
F頂件=K頂件F落料
=0.06×22.48
=1.35（kN）
2.6 選擇壓力機(jī)
根據(jù)以上幾個(gè)工序所計(jì)算的結(jié)果，落料的沖裁力最大，且該沖壓件選擇的模具類型為復(fù)合模，這類模具在工作的時(shí)候是一道工序一道工序完成，在受力的時(shí)候各個(gè)工序所受的力不和其他的工序重疊，就是說在選設(shè)備的時(shí)候根據(jù)在各個(gè)工序里的最大力來選，且所受的力在安全范圍內(nèi)。所以此副模具就是根據(jù)落料工序的總工藝力來初選壓力機(jī)。
1 對(duì)于落料沖裁工序,壓力機(jī)的公稱力應(yīng)大于或等于沖裁時(shí)總沖壓力的1.1-1.3倍 P≥(1.1-1.3)
其中P-------壓力機(jī)的公稱力
F-------沖裁力的總沖壓力
P ≥ 1800.11KN
2 沖壓設(shè)備的選擇
沖壓設(shè)備選擇的要求：
1) 壓力機(jī)的行程大小，應(yīng)能保證成型零件的取出與毛坯的放入。
2) 壓力機(jī)的工作臺(tái)面尺寸應(yīng)大于沖模的平面尺寸，還需留有安裝固定的余地，但是在過大的工作臺(tái)上安裝很小尺寸的沖模時(shí)，工作臺(tái)的受力條件也是不理想的。所選的壓力機(jī)的工作臺(tái)面尺寸應(yīng)與沖模的平面尺寸相適應(yīng)。
3) 模具的閉合高度：模具在閉合時(shí)，上模座的上表面到下模座的下表面之間的距離。壓力機(jī)的閉合高度H：滑塊在下死點(diǎn)時(shí)，工作臺(tái)面到滑塊下端面的距離。該距離一般是可以調(diào)整的，故一般的壓力機(jī)均由最大閉合高度和最小閉合高度。
4) 壓力機(jī)的噸位要與總的沖壓力相適應(yīng)。
根據(jù)所計(jì)算出的總沖壓力。初步選擇公稱壓力為2500kN的閉式單點(diǎn)單動(dòng)壓力機(jī)J31-250。其基本參數(shù)如下表1：
表1 J31-250基本參數(shù)
公稱壓力
2500kN
滑塊行程
315mm
標(biāo)準(zhǔn)行程次數(shù)
20次/min
最大閉合高度
490mm
閉合高度調(diào)節(jié)量
200mm
工作臺(tái)尺寸（左右）
1000mm
工作臺(tái)尺寸（前后）
950mm
標(biāo)稱壓力行程
10.4mm
導(dǎo)軌間距離
900mm
滑快底面前后尺寸
850mm
拉深墊壓緊力
400KN
2.7 壓力中心計(jì)算
因?yàn)樵摿慵菍?duì)稱圖形，并按照如下式進(jìn)行計(jì)算得：
沖孔：（3.8）
（3.9）
沖裁邊：（3.10）
（4.11）
式中：——沖孔時(shí)指各種孔的中心位置；
沖裁邊時(shí)指各線段中心坐標(biāo)；
——沖各孔時(shí)所用壓力；
——各線段長(zhǎng)度；
——壓力中心坐標(biāo)。
由于零件是對(duì)稱圖形,即壓力中心在中心.
第3章 排樣設(shè)計(jì)計(jì)算
根據(jù)工件的開關(guān)，確定采用無廢料的排樣方法不可能做到，但能采用有廢料和少?gòu)U料的排樣方法。經(jīng)多次排樣計(jì)算決定采用，
1）搭邊設(shè)計(jì)
板料厚度t=0.8mm, 所以a=1mm, a=1.4mm。
送料步距A=15mm, 條料寬度B=25mm。
2）排樣布局
3）材料利用率計(jì)算：
S=206.23mm
=×100%=×100%=×100%
=55%
式中，—材料利用率；
S—工件的實(shí)際面積；
S—所用材料面積，包括工件面積與廢料面積；
A—步距（相鄰兩個(gè)制件對(duì)應(yīng)點(diǎn)的距離）
B—條料寬度。
第4章 工作零件的設(shè)計(jì)
4.1 模具間隙的確定
沖裁件的工藝性分析是指沖裁件對(duì)沖裁的適應(yīng)性，即沖裁件的形狀結(jié)構(gòu)、尺寸的大小及偏差等是否符合加工的工藝要求。沖裁件的工藝性是否合理對(duì)沖裁件的質(zhì)量、模具的壽命和生產(chǎn)率有很大影響。
沖裁間隙指凸、凹模刃口間隙的距離。沖裁間隙是沖壓工藝和模具設(shè)計(jì)中的重要參數(shù)，它直接影響沖裁件的質(zhì)量、模具壽命和力能的消耗，應(yīng)根據(jù)實(shí)際情況和需要合理的選用。沖裁間隙有單面間隙和雙面間隙之分。根據(jù)沖裁件尺寸精度、剪切質(zhì)量、模具壽命和力能消耗等主要因素，將金屬材料沖裁間隙分成三種類型[3]：Ⅰ類（小間隙），Ⅱ類（中等間隙），Ⅲ類（大間隙）。
1、間隙過小時(shí)，由凹模刃口處產(chǎn)生的裂紋在繼續(xù)加壓的情況下將產(chǎn)生二次剪切，繼而被擠入凹模。這樣，制件端面中部留下撕裂面，而兩頭出現(xiàn)光亮帶，在端面出現(xiàn)擠長(zhǎng)的毛刺。毛刺雖長(zhǎng)單易去除，只要中間撕裂不是很深，仍可用。
2、間隙過大時(shí)，材料的拉深與拉伸增大，拉伸應(yīng)力增大，材料容易被撕裂，使制件的光亮代減小，圓角與斷裂都增大，毛刺大而厚，難去除。所以隨著間隙的增大，制件的斷裂面的傾斜度的增大，毛刺增高。
沖裁件的尺寸精度是指沖裁件的實(shí)際尺寸與公差尺寸的差值。這個(gè)差值包含兩個(gè)方面的偏差，一是沖裁件相對(duì)于凸模或凹模尺寸的偏差，一是模具本身的制造偏差。其中凸、凹模間隙是影響凸?；虬寄３叽绲钠畹闹饕蛩?。
當(dāng)凸、凹模的間隙較大時(shí)，材料所受拉伸作用增大。沖裁完后，材料的彈性恢復(fù)使落料尺寸小于凹模尺寸，沖孔孔徑大于凸模直徑。此時(shí)穹彎的彈性恢復(fù)方向與其相反，鼓薄板沖裁時(shí)制件尺寸偏差減小。在間隙較小時(shí)，由于材料受凸、凹模擠壓力大，故沖裁完后，材料的彈性恢復(fù)使落料件尺寸增大，沖孔孔徑減小。
隨著間隙的增大，材料所受的拉力增大，材料容易斷裂分離，因此沖裁力減小。但是繼續(xù)增大間隙時(shí)，會(huì)因從凸、凹模刃口處產(chǎn)生的裂紋不重合，沖裁力減小。
由于間隙的增大，使沖裁件的光亮面變小，落料尺寸小于凹模尺寸，沖孔尺寸大于凸模尺寸，因而使卸料力、推件力或頂件力也隨之減小。但是，間隙繼續(xù)增大時(shí)，因?yàn)槊淘龃?，引起卸料力、頂件力也迅速增大?
沖裁模具的壽命通常以保證獲得合格產(chǎn)品時(shí)的沖裁次數(shù)來表示。沖裁過程中模具的失效形式一般有：磨損、變形、崩刃和凹模刃口漲裂四種。
間隙增大時(shí)可使沖裁力、卸料力等減小，因而模具的磨損也減??；但當(dāng)間隙繼續(xù)增大時(shí)，卸料力增加，又影響模具磨損，一般間隙為（10%--15%）t時(shí)磨損最小模具壽命較高。間隙小時(shí)，落料件梗塞在凹模洞口的漲裂力也大。
由以上分析可見，凸、凹模對(duì)沖裁件質(zhì)量、沖裁力、模具壽命等都有很大的影響。因此，在設(shè)計(jì)和制造模具時(shí)有一個(gè)合理的間隙值，以保證沖裁件的斷面質(zhì)量好，尺寸精度高，所需沖裁力小，模具壽命高。生產(chǎn)中常選用一個(gè)適當(dāng)?shù)姆秶鳛楹侠黹g隙。這個(gè)范圍的最小值稱為最小合理間隙,最大值稱為最大合理間隙。設(shè)計(jì)與制造新模具時(shí)采用最小合理間隙值。
確定合理間隙的理論根據(jù)是以凸、凹模刃口處產(chǎn)生的裂紋相重合為依據(jù)?？梢杂?jì)算得到合理間隙值，計(jì)算公式如下：
Z=2t(1- )tanβ2-5
由上式可看出，間隙z與材料厚度t、相對(duì)切入深度/t及破裂角β有關(guān)。對(duì)硬而脆的材料， /t有較小值時(shí)，則合理間隙值較大。對(duì)軟而韌的材料，/t有較大值，則合理間隙值較小。板厚越大，合理間隙越大。
由于理論計(jì)算在生產(chǎn)中不便使用，故目前廣泛使用的是經(jīng)驗(yàn)數(shù)據(jù)。
表2-1沖裁模較大單面間隙
材料
厚度
08、10、35、09Mn、Q235、B3
紫銅
40、50
65Mn
最小值
最大值
最小值
最大值
最小值
最大值
最小值
最大值
0.5
0.020
0.030
0.020
0.030
0.020
0.030
0.020
0.030
0.6
0.024
0.036
0.024
0.036
0.024
0.036
0.024
0.036
0.8
0.036
0.052
0.036
0.052
0.036
0.052
0.036
0.052
0.9
0.045
0.063
0.045
0.063
0.045
0.063
0.045
0.063
1.0
0.050
0.070
0.050
0.070
0.050
0.070
0.0450
0.063
1.2
0.063
0.090
0.66
0.090
0.066
0.090
1.5
0.066
0.120
0.085
0.120
0.085
0.120
2.0
0.123
0.180
0.130
0.190
0.130
0.190
間隙的選擇可以按照如下原則：對(duì)于斷面垂直度與尺寸公差要求較高的工件，選擇較小的合理間隙值。這時(shí)沖裁力與模具壽命作為次要因素來考慮。對(duì)于斷面垂直度與尺寸公差要求的前提下，應(yīng)以降低沖裁力、提高模具壽命為主，采用較大的合理間隙值。
落料部分以落料凹模為基準(zhǔn)計(jì)算，落料凸模按間隙值配制;沖孔部分明中孔凸模為基準(zhǔn)計(jì)算，沖孔凹模按間隙值配制。既以落料凹模、沖孔凸模為基準(zhǔn)，凸凹模按間隙值配制。
零件外形為異形，為便于凸凹模加工，保證凸凹模之間的間隙，采用凸凹模配合加工。
公式：
沖孔時(shí)： d= (d+x) （3—10）
d= (d+x+Z) (3—11)
落料時(shí)： D= (D-x) （3—12）
D= (D+x+Z) (3—13)
孔距尺寸：L= (L+0.5+)±△／8 （3—14）
式中 d， d－分別為沖孔凸模和凹模的刃口尺寸；
D ，D－分別為落料凸模和凹模的刃口尺寸；
d，D－分別為沖孔件和落料件的最小和最大極限尺寸；
L－兩孔中心距的最小極限尺寸；
△－工件公差；
Z－最小合理間隙；
X－磨損系數(shù)。
4.2 沖孔刃口尺寸計(jì)算
△=0.36
X=0.5
s=△/4
d(6.5) mm=(d+x)=(6.5+0.5×0.36)-s0=6.68
4.3 落料刃口尺寸計(jì)算
D1(22.3)mm = (D-x)=(22.3-0.5×0.25)0+0.063=22.175
D1(14)mm = (D-x)=(14-0.5×0.25)0+0.063=13.875
D1(6)mm = (D-x)=(6-0.5×0.25)0+0.063=5.875
第5章 輔助結(jié)構(gòu)零件的設(shè)計(jì)及選用
5.1 模具總體結(jié)構(gòu)設(shè)計(jì)
廢料由凸模入凹模洞口中，積累到一定數(shù)量，由下模漏料孔排出，不必清除廢料，操作方便，應(yīng)用很廣，但工件表面平直度較差，凸凹模承受的張力較大，因此凸凹模的壁厚應(yīng)嚴(yán)格控制，以免強(qiáng)度不足。
5.2 凸凹模固定板
凸凹模固定板形狀與凹模板一致，如圖所示：
5.3凸模固定板
凸模固定板將凸模固定在模座上，其平面輪廓尺寸與凹模板外形尺寸相同，但還應(yīng)考慮緊固螺釘及銷釘?shù)奈恢?。固定板的凸模安裝孔與凸模采用過渡配合H7/m6、H7/n6，壓裝后將凸模端面與固定板一起磨平。凸模固定板為圓形，厚度一般取凹模厚度的0.6~0.8倍。
5.4 墊板
沖裁時(shí)，如果凸模的端部對(duì)模座的壓應(yīng)力超過模座材料的許用壓應(yīng)力，這時(shí)需要在凸模端部與模座之間加上一塊強(qiáng)度較高的墊板。即下列情況下雨加墊板。
式中 —凸模端面的壓應(yīng)力，其數(shù)值為；
—模座材料下雨壓應(yīng)力，其數(shù)值：鑄鐵約為100MPa，鋼約為200 MPa；
—沖裁力；
—凸模上端面面積。
墊板的下載與凸模固定板一致，厚度一般取4～12mm。墊板淬硬后兩面應(yīng)磨平，表面粗糙度Ra≤0.32～0.63。
由于本套模具選用壓入式模柄，在上模座與凸模固定板之間也必須安裝墊板
5.5 卸料板
卸料板同樣為和凹模板一致，卸料板材料選A3或（45）鋼，不用熱處理淬硬。
取卸料板與凸凹模的雙面間隙為0.1～0.3mm.
卸料板上設(shè)置幾個(gè)卸料螺釘。卸料釘尾部應(yīng)留有足夠的行程空間。卸料螺釘擰緊后，應(yīng)使卸料板超出凸模端面lmm，有誤差時(shí)通過在螺釘與卸料板之間安裝墊片來調(diào)整。如下圖所示：
5.6 操作與定位方式
零件中批量生產(chǎn),安排生產(chǎn)可采用手工送料方式能夠達(dá)到批量生產(chǎn),且能降低模具成本,因此采用手工送料方式.零件尺寸較大，厚度較高，保證孔的精度及較好的定位，宜采用導(dǎo)料板導(dǎo)向，導(dǎo)正銷導(dǎo)正，為了提高材料利用率采用始用擋料銷和固定擋料銷。
第6章 模具的裝配圖的設(shè)計(jì)
6.1 零件的技術(shù)要求
1．沖模零件不允許有裂紋，工作表面不允許有劃痕、機(jī)械損傷、銹蝕等表面缺陷。經(jīng)熱處理后的零件硬度應(yīng)均勻、不允許有軟點(diǎn)和脫碳區(qū)，并清除氧化物等。
2．沖模各零件的材料和熱處理硬度應(yīng)優(yōu)先按模具設(shè)計(jì)手冊(cè)中標(biāo)準(zhǔn)選用，允許采用性能高于兩表規(guī)定的其他鋼種。
3．零件圖中普通螺紋的基本尺寸應(yīng)符合GB/T196的規(guī)定，選用極限與配合應(yīng)符合GB/T197的規(guī)定。
4．固定板、凹模、墊板、卸料板的形狀和位置公差按GB/T1182-1996等的規(guī)定。
5．沖模各零件的幾何形狀、尺寸精度、表面粗糙度等應(yīng)符合設(shè)計(jì)圖樣的要求。
6．零件圖中未注公差尺寸的極限偏差按GB/T1804的規(guī)定。
7．零件圖中未注的形狀和位置公差按GB/T1184-1996的規(guī)定。
8．沖裁模之凸、凹模刃口及側(cè)刃必須鋒利，不允許有崩刃、缺刃和機(jī)械損壞。
9．沖裁模凹模工作孔不允許有倒錐度。
6.2 裝配技術(shù)要求
1．裝配時(shí)應(yīng)保證凸、凹模之間的間隙均勻一致，配合間隙符合設(shè)計(jì)要注，不允許采用使凸、凹模變形的方法來修正間隙。
2．推料、卸料機(jī)構(gòu)必須靈活，卸料板或推件器在沖模開啟狀態(tài)時(shí)，一般應(yīng)突出凸凹模表面0.5-1mm。
4．各接合面保證密合。
5．沖壓的凹模刃口的高度，按設(shè)計(jì)要求制造，其漏料孔應(yīng)保證暢通，一般應(yīng)比刃口大0.2-2mm
6.沖模所有活動(dòng)部分的移動(dòng)應(yīng)平穩(wěn)靈活，無滯止現(xiàn)象，滑塊、楔埠在固定滑動(dòng)面移動(dòng)時(shí)，其最小面積不少于其面積的一半。
7．各緊固用的螺釘、鎖釘不得松動(dòng)，并保證螺釘和銷釘?shù)亩嗣娌煌怀錾?、下模座平面?
8．各卸料螺釘沉孔深度應(yīng)保證一致。
9．各卸料螺釘、頂桿的長(zhǎng)度應(yīng)保證一致。
10．凸模的垂直度必須在凸凹模間隙值允許范圍內(nèi)。
11．沖模的裝配必須符合模具裝配圖、明細(xì)表及技術(shù)條件規(guī)定。
12．凸模、凸凹模等與固定板的配合一般按H7/h6或H7/m6，保證工作穩(wěn)定可靠。
6.3 模具安裝要求
1.上模座上平面對(duì)下模座下平面的平行度，導(dǎo)柱軸心線對(duì)下模座下平面的垂直度和導(dǎo)套孔軸心線對(duì)上模座上平面的垂直度均應(yīng)達(dá)到規(guī)定的精度要求。
2.模架的上模沿導(dǎo)柱上、下移動(dòng)應(yīng)平穩(wěn)，無阻滯現(xiàn)象。
3.裝配好的模具,其封閉高度應(yīng)符合圖樣規(guī)定的要求。
6.4 復(fù)合模的調(diào)試要求
模具按圖紙技術(shù)要求加工與裝配后，必須在符合實(shí)際生產(chǎn)條件的環(huán)境中進(jìn)行試模，可以發(fā)現(xiàn)模具設(shè)計(jì)與制造的缺陷，發(fā)現(xiàn)問題必須及時(shí)解決。找出產(chǎn)生的原因，進(jìn)行改正。對(duì)模具進(jìn)行適當(dāng)?shù)恼{(diào)整和修理后再進(jìn)行試模，直到模具能正常工作，才能將模具正式交付生產(chǎn)使用。
6.5 主要組件的裝配
1．模柄的裝配，在安裝凸模固定板和墊板之前，應(yīng)先把模柄裝好,用角尺檢查模柄與上模座上平面的垂直度。
2. 凸模和凸模固定板的裝配配合要求為H7/m6。裝配時(shí)，先在壓力機(jī)上將凸模壓入凸模固定板內(nèi)，檢查凸模的垂直度，然后將固定板的上平面與凸模尾部一起磨平，為了保持凸模刃口鋒利還應(yīng)將凸模的端面磨平。
3. 導(dǎo)柱與導(dǎo)套的技術(shù)要求及裝配，組成模架各零件均應(yīng)符合相應(yīng)的技術(shù)條件，其中特別重要的是每對(duì)導(dǎo)柱，導(dǎo)套的配合間隙應(yīng)符合要求。壓入上、下模座的導(dǎo)柱、導(dǎo)柱離其它安裝表面應(yīng)有1-2 mm的距離，壓入后就應(yīng)牢固。裝配成套的模架，各零件的工作表不應(yīng)有碰傷，裂紋以及其它機(jī)械損傷。
第8章 模具工作過程
有上面可知模具為復(fù)合沖裁模。上模部分有凹模與沖孔凸模，通過沖孔凸模固定板、墊板由銷釘定位、螺釘固定裝在上模座上。凸凹模通過凸凹模固定、墊板裝在下模座上。采用導(dǎo)柱導(dǎo)套導(dǎo)向，導(dǎo)柱布置在兩側(cè)。為防止裝反，兩個(gè)導(dǎo)柱的直徑有同。為了推件與卸料，上模裝有由推桿、推板、推桿與推件板組成的剛性系統(tǒng)。下模裝有由卸料、卸料螺釘與橡皮組成的彈性卸料系統(tǒng)。彈性卸料對(duì)條料起校平作用。沖載時(shí)，落料凹模將彈性卸料板壓下，沖孔凸模也進(jìn)入沖孔凹?？字?，同時(shí)完成沖孔與落料。當(dāng)上?；爻虝r(shí)，彈性卸料板在橡作用下將條料從凸凹模上卸下，而推桿受到橫桿的推動(dòng)，通過推板、推桿與推件板將沖件從凹中推出，沖孔廢料由凸凹?？字新┏?。條料的定位依靠左側(cè)的兩個(gè)活動(dòng)導(dǎo)料的方法在復(fù)
合模中的應(yīng)用較多，它不影響彈性卸料板對(duì)條料的壓平作用。
而倒裝復(fù)合模的主要的優(yōu)點(diǎn)是廢料能直接從壓力機(jī)漏料孔落下，沖載件從上模落下，比較容易取出這些排出件，因此操作方便安全，有利于倒裝復(fù)合模的安裝送料裝置，生產(chǎn)效率較高，所以應(yīng)用比較廣泛。
結(jié)論與展望
本次沖壓模具的設(shè)計(jì)歷時(shí)幾個(gè)月，系統(tǒng)綜合應(yīng)用了大學(xué)期間所學(xué)的相關(guān)知識(shí)。通過本次設(shè)計(jì)，基本上已經(jīng)掌握了沖壓模具的設(shè)計(jì)過程和方法，查閱文獻(xiàn)收集資料途徑，培養(yǎng)了良好的設(shè)計(jì)思路，為以后從事模具設(shè)計(jì)工作打下了堅(jiān)實(shí)的基礎(chǔ)。
為了提高生產(chǎn)效率和降低成本，在設(shè)計(jì)中盡量對(duì)模具進(jìn)行設(shè)計(jì)。但這也帶來如模具內(nèi)部結(jié)構(gòu)復(fù)雜，不便于安裝等問題。原模存在著最小壁厚的問題，最小壁厚取值大，浪費(fèi)材料，取值小模具的強(qiáng)度不能保證，設(shè)計(jì)時(shí)解決了最小壁厚與搭邊值之間的矛盾；使用定位裝置，避免了毛坯的偏移；凸模在工作時(shí)保證其強(qiáng)度時(shí)存在問題；給清理工作帶來不便，應(yīng)該改進(jìn)。
致謝
本設(shè)計(jì)的撰寫是在我的指導(dǎo)教師的精心指導(dǎo)和關(guān)心下完成的。從課題的選擇、方案制定、工作實(shí)施到設(shè)計(jì)的撰寫、修改無不滲透著老師的心血。老師以他們淵博的學(xué)識(shí)、卓越的才智、嚴(yán)謹(jǐn)?shù)闹螌W(xué)精神和求實(shí)創(chuàng)新的工作作風(fēng)使我受益非淺，在學(xué)習(xí)和設(shè)計(jì)過程中給予我很大的啟迪與幫助，給我留下了極為深刻的印象，使我對(duì)以后的工作充滿信心。
在此設(shè)計(jì)完成之際，謹(jǐn)向幾年來關(guān)心我的工程技術(shù)學(xué)院所有老師致以崇高的敬意和衷心的感謝!同時(shí)在設(shè)計(jì)過程中得到了同組同學(xué)的大力幫助和支持，在此一并致謝。
參考文獻(xiàn)
[1]《沖模設(shè)計(jì)手冊(cè)》編寫組.模具設(shè)計(jì)手冊(cè)[M].北京:機(jī)械工業(yè)出版社,1999
[2]《冷沖壓模具設(shè)計(jì)》[M].北京: 化學(xué)工業(yè)出版社，2010
[3]王芳.冷沖模具指導(dǎo)書[M].北京:機(jī)械工業(yè)出版社,1998
[4]王以真.實(shí)用揚(yáng)器技術(shù)手冊(cè)[M].北京:國(guó)防工業(yè)出版社,2003
[5]王新華,袁聯(lián)富.沖模結(jié)構(gòu)圖冊(cè)[M].北京:機(jī)械工業(yè)出版社,2003
[6]陳錦昌,劉就女等.計(jì)算機(jī)工程制圖[M].廣州:華南理工大學(xué)出版社,1999
[7]劉鴻文.材料力學(xué)[M].北京:高等教育出版社,1999
[8]黃毅宏,李明輝.模具制造工藝[M].北京:機(jī)械工業(yè)出版社,1999
[9]模具實(shí)用技術(shù)叢書編委會(huì).沖模設(shè)計(jì)應(yīng)用實(shí)例[M].北京:機(jī)械工業(yè)出版社,1999
[10]廖念釘,古瑩奄等.互換性與技術(shù)測(cè)量[M].北京:中國(guó)計(jì)量出版社,2001
[11]王煥庭,李茅華、徐善國(guó).工機(jī)械工程材料[M].大連：大連理工大學(xué)出版社,2002
[12]黨根茂,駱志斌等.模具設(shè)計(jì)與制造[M].西安:西安電子科技大學(xué)出版社,2001
INEEL/CON-2000-00104 PREPRINT Spray-Formed Tooling for Injection Molding and Die Casting Applications K. M. McHugh B. R. Wickham June 26, 2000 June 28, 2000 International Conference on Spray Deposition and Melt Atomization This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third partys use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the U.S. Government or the sponsoring agency. BECHTEL BWXT IDAHO, LLC 1 Spray-Formed Tooling For Injection Molding and Die Casting Applications Kevin M. McHugh and Bruce R. Wickham Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83415-2050 e-mail: kmm4inel.gov Abstract Rapid Solidification Process (RSP) Tooling is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described. Introduction Molds, dies, and related tooling are used to shape many of the plastic and metal components we use every day at home or at work. The process involves machining the negative of a desired part shape (core and cavity) from a forged tool steel or a rough metal casting, adding cooling channels, vents, and other mechanical features, followed by grinding. Many molds and dies undergo heat treatment (austenitization/quench/temper) to improve the properties of the steel, followed by final grinding and polishing to achieve the desired finish 1. Conventional fabrication of molds and dies is very expensive and time consuming because: Each is custom made, reflecting the shape and texture of the desired part. The materials used to make tooling are difficult to machine and work with. Tool steels are the workhorse of industry for long production runs. Machining tool steels is capital equipment intensive because specialized equipment is often needed for individual machining steps. Tooling must be machined accurately. Oftentimes many individual components must fit together correctly for the final product to function properly. 2 Costs for plastic injection molds vary with size and complexity, ranging from about $10,000 to over $300,000 (U.S.), and have lead times of 3 to 6 months. Tool checking and part qualification may require an additional 3 months. Large die-casting dies for transmissions and sheet metal stamping dies for making automobile body panels may cost more than $1million (U.S.). Lead times are usually greater than 40 weeks. A large automobile company invests about $1 billion (U.S.) in new tooling each year to manufacture the components that go into their new line of cars and trucks. Spray forming offers great potential for reducing the cost and lead time for tooling by eliminating many of the machining, grinding, and polishing unit operations. In addition, spray forming provides a powerful means to control segregation of alloying elements during solidification and carbide formation, and the ability to create beneficial metastable phases in many popular ferritic tool steels. As a result, relatively low temperature precipitation hardening heat treatment can be used to tailor properties such as hardness, toughness, thermal fatigue resistance, and strength. This paper describes the application of spray forming technology for producing H13 tooling for injection molding and die casting applications, and the benefits of low temperature heat treatment. RSP Tooling Rapid Solidification Process (RSP) Tooling, is a spray forming technology tailored for producing molds and dies 2-4. The approach combines rapid solidification processing and net- shape materials processing in a single step. The general concept involves converting a mold design described by a CAD file to a tooling master using a suitable rapid prototyping (RP) technology such as stereolithography. A pattern transfer is made to a castable ceramic, typically alumina or fused silica (Figure 1). This is followed by spray forming a thick deposit of tool steel (or other alloy) on the pattern to capture the desired shape, surface texture and detail. The resultant metal block is cooled to room temperature and separated from the pattern. Typically, the deposits exterior walls are machined square, allowing it to be used as an insert in a holding block such as a MUD frame 5. The overall turnaround time for tooling is about three days, stating with a master. Molds and dies produced in this way have been used for prototype and production runs in plastic injection molding and die casting. Figure 1. RSP Tooling processing steps. 3 An important benefit of RSP Tooling is that it allows molds and dies to be made early in the design cycle for a component. True prototype parts can be manufactured to assess form, fit, and function using the same process planned for production. If the part is qualified, the tooling can be run in production as conventional tooling would. Use of a digital database and RP technology allows design modifications to be easily made. Experimental Procedure An alumina-base ceramic (Cotronics 780 6) was slurry cast using a silicone rubber master die, or freeze cast using a stereolithography master. After setting up, ceramic patterns were demolded, fired in a kiln, and cooled to room temperature. H13 tool steel was induction melted under a nitrogen atmosphere, superheated about 100C, and pressure-fed into a bench-scale converging/diverging spray nozzle, designed and constructed in-house. An inert gas atmosphere within the spray apparatus minimized in-flight oxidation of the atomized droplets as they deposited onto the tool pattern at a rate of about 200 kg/h. Gas-to-metal mass flow ratio was approximately 0.5. For tensile property and hardness evaluation, the spray-formed material was sectioned using a wire EDM and surface ground to remove a 0.05 mm thick heat-affected zone. Samples were heat treated in a furnace that was purged with nitrogen. Each sample was coated with BN and placed in a sealed metal foil packet as a precautionary measure to prevent decarburization. Artificially aged samples were soaked for 1 hour at temperatures ranging from 400 to 700C, and air cooled. Conventionally heat treated H13 was austenitized at 1010C for 30 min., air quenched, and double tempered (2 hr plus 2 hr) at 538C. Microhardness was measured at room temperature using a Shimadzu Type M Vickers Hardness Tester by averaging ten microindentation readings. Microstructure of the etched (3% nital) tool steel was evaluated optically using an Olympus Model PME-3 metallograph and an Amray Model 1830 scanning electron microscope. Phase composition was analyzed via energy- dispersive spectroscopy (EDS). The size distribution of overspray powder was analyzed using a Microtrac Full Range Particle Analyzer after powder samples were sieved at 200 m to remove coarse flakes. Sample density was evaluated by water displacement using Archimedes principle and a Mettler balance (Model AE100). A quasi 1-D computer code developed at INEEL was used to evaluate multiphase flow behavior inside the nozzle and free jet regions. The codes basic numerical technique solves the steady- state gas flow field through an adaptive grid, conservative variables approach and treats the droplet phase in a Lagrangian manner with full aerodynamic and energetic coupling between the droplets and transport gas. The liquid metal injection system is coupled to the throat gas dynamics, and effects of heat transfer and wall friction are included. The code also includes a nonequilibrium solidification model that permits droplet undercooling and recalescence. The code was used to map out the temperature and velocity profile of the gas and atomized droplets within the nozzle and free jet regions. 4 Results and Discussion Spray forming is a robust rapid tooling technology that allows tool steel molds and dies to be produced in a straightforward manner. Examples of die inserts are given in Figure 2. Each was spray formed using a ceramic pattern generated from a RP master. Figure 2. Spray-formed mold inserts. (a) Ceramic pattern and H13 tool steel insert. (b) P20 tool steel insert. Particle and Gas Behavior Particle mass frequency and cumulative mass distribution plots for H13 tool steel sprays are given in Figure 3. The mass median diameter was determined to be 56 m by interpolation of size corresponding to 50% cumulative mass. The area mean diameter and volume mean diameter were calculated to be 53 m and 139 m, respectively. Geometric standard deviation, d =(d 84 /d 16 ) , is 1.8, where d 84 and d 16 are particle diameters corresponding to 84% and 16% cumulative mass in Figure 3. 5 Figure 3. Cumulative mass and mass frequency plots of particles in H13 tool step sprays. Figure 4 gives computational results for the multiphase velocity flow field (Figure 4a), and H13 tool steel solid fraction (Figure 4b), inside the nozzle and free jet regions. Gas velocity increases until reaching the location of the shock front, at which point it precipitously decreases, eventually decaying exponentially outside the nozzle. Small droplets are easily perturbed by the velocity field, accelerating inside the nozzle and decelerating outside. After reaching their terminal velocity, larger droplets (150 m) are less perturbed by the flow field due to their greater momentum. It is well known that high particle cooling rates in the spray jet (10 3 -10 6 K/s) and bulk deposit (1- 100 K/min) are present during spray forming 7. Most of the particles in the spray have undergone recalescence, resulting in a solid fraction of about 0.75. Calculated solid fraction profiles of small (30 m) and large (150 m) droplets with distance from the nozzle inlet, are shown in Figure 4b. Spray-Formed Deposits This high heat extraction rate reduces erosion effects at the surface of the tool pattern. This allows relatively soft, castable ceramic pattern materials to be used that would not be satisfactory candidates for conventional metal casting processes. With suitable processing conditions, fine 6 Figure 4. Calculated particle and gas behavior in nozzle and free jet regions. (a) Velocity profile. (b) Solid fraction. 7 surface detail can be successfully transferred from the pattern to spray-formed mold. Surface roughness at the molding surface is pattern dependent. Slurry-cast commercial ceramics yield a surface roughness of about 1 m Ra, suitable for many molding applications. Deposition of tool steel onto glass plates has yielded a specular surface finish of about 0.076 m Ra. At the current state of development, dimensional repeatability of spray-formed molds, starting with a common master, is about 0.2%. Chemistry The chemistry of H13 tool steel is designed to allow the material to withstand the temperature, pressure, abrasion, and thermal cycling associated with demanding applications such as die casting. It is the most popular die casting alloy worldwide and second most popular tool steel for plastic injection molding. The steel has low carbon content (0.4 wt.%) to promote toughness, medium chromium content (5 wt%) to provide good resistance to high temperature softening, 1 wt% Si to improve high temperature oxidation resistance, and small molybdenum and vanadium additions (about 1%) that form stable carbides to increase resistance to erosive wear 8. Composition analysis was performed on H13 tool steel before and after spray forming. Results, summarized in Table 1, indicate no significant variation in alloy additions. Table 1. Composition of H13 tool steel Element C Mn Cr Mo V Si Fe Stock H13 0.41 0.39 5.15 1.41 0.9 1.06 Bal. Spray Formed H13 0.41 0.38 5.10 1.42 0.9 1.08 Bal. Microstructure The size, shape, type, and distribution of carbides found in H13 tool steel is dictated by the processing method and heat treatment. Normally the commercial steel is machined in the mill annealed condition and heat treated (austenitized/quenched/tempered) prior to use. It is typically austenitized at about 1010C, quenched in air or oil, and carefully tempered two or three times at 540 to 650C to obtain the required combination of hardness, thermal fatigue resistance, and toughness. Commercial, forged, ferritic tool steels cannot be precipitation hardened because after electroslag remelting at the steel mill, ingots are cast that cool slowly and form coarse carbides. In contrast, rapid solidification of H13 tool steel causes alloying additions to remain largely in solution and to be more uniformly distributed in the matrix 9-11. Properties can be tailored by artificial aging or conventional heat treatment. A benefit of artificial aging is that it bypasses the specific volume changes that occur during conventional heat treatment that can lead to tool distortion. These specific volume changes occur as the matrix phase transforms from ferrite to austenite to tempered martensite and must be accounted for in the original mold design. However, they cannot always be reliably predicted. Thin sections in the insert, which may be desirable from a design and production standpoint, are oftentimes not included as the material has a tendency to slump during austenitization or distort 8 during quenching. Tool distortion is not observed during artificial aging of spray-formed tool steels because there is no phase transformation. An optical photomicrograph of spray-formed H13 is shown in Figure 5 together with an SEM image, in backscattered electron (BSE) mode. Energy dispersive spectroscopic (EDS) composition analysis of some features in the photomicrographs is also given. While exact quantitative data is not possible due to sampling volume limitations, results suggest that grain boundaries are particularly rich in V. Intragranular (matrix) regions are homogeneous and rich in Fe. X-ray diffraction analysis indicates that the matrix phase is primarily ferrite (bainite) with very little retained austenite, and that the alloying elements are largely in solution. Discrete intragranular carbides are relatively rare, very small (about 0.1 m) and predominately vanadium-rich MC carbides. M 2 C carbides are not observed. Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0.61 32.13 6.68 0.17 2.05 58.36 Spot #2 (wt%) 1.59 0.79 5.35 0.28 2.28 89.72 Figure 5. Photomicrographs of as-deposited H13 tool steel. 3% nital etch. (a) Optical photomicrograph. (b) SEM image (BSE mode) near a grain boundary. Table gives EDS composition of numbered features. 9 Figure 6 illustrates the microstructure of spray-formed H13 aged at 500C for 1 hr. During aging, grain boundaries remain well defined, perhaps coarsening slightly compared to as- deposited H13 (Figure 5). The most prominent change is the appearance of very fine (0.1 m diameter) vanadium-rich MC carbide precipitates. The precipitates are uniformly distributed throughout the matrix and increase the hardness and wear resistance of the tool steel. Increasing the soak temperature to 700C results in prominent carbide coarsening, the formation of M 7 C 3 and M 6 C carbides, and a decrease in hardness. The photomicrographs of Figure 7 illustrate the dramatic change in carbide size. BSE imaging clearly differentiates Mo/Cr-rich carbides from V-rich carbides, shown as light and dark areas, respectively, in Figure 7. EDS analysis of these carbides is also given in Figure 7. Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0.06 13.80 7.20 2.64 2.44 73.86 Spot #2 (wt%) 1.52 0.82 5.48 0.23 2.38 89.57 Figure 6. Photomicrographs of spray-formed/aged H13 tool steel. 500C soak for 1 hr. 3% nital etch. (a) Optical photomicrograph. (b) SEM image (BSE mode) near a grain boundary. Table gives EDS composition of numbered features. 10 Element Si V Cr Mn Mo Fe Spot #1 (wt%) 0 82.27 9.01 0 4.33 4.39 Spot #2 (wt%) 0 5.30 25.70 0 55.55 13.45 Spot #3 (wt%) 1.60 0.88 6.32 0.28 2.92 88.00 Figure 7. SEM Photomicrograph (BSE mode) of spray-formed/aged H13 tool steel showing adjacent V-rich (dark) and Mo/Cr-rich (light) carbides. 700C soak for 1/2 hr, 3% nital etch. Table gives EDS composition of numbered features. Material Properties Porosity in spray-formed metals depends on processing conditions. The average as-deposited density of spray-formed H13 was 98-99% of theoretical, as measured by water displacement using Archimedes principle. As-deposited hardness was typically about 59 HRC, harder than commercial forged and heat treated material (28 to 53 HRC depending on tempering temperature), and significantly harder than annealed H13 (200 HB). The high hardness is attributable to lattice strain due to quenching stresses and supersaturation. As shown in Figure 8, hardness can be varied over a wide range by artificial aging. 59 HRC as- deposited samples were given isochronal (1 hr) soaks at 50C increments from 400 to 700C, air cooled, and evaluated for microhardness. At 400C, a small decrease in hardness was observed, presumably due to stress relieving. As the soak temperature was further increased, hardness rose to a peak hardness of approximately 62 HRC at 500C. Higher soak temperature resulted in a drop in hardness as carbide particles coarsened. Peak age hardness in spray-formed H13 tool steel is notably higher than that of commercial hardened material. Normally, commercial H13 dies used in die casting are tempered to about 40 to 45 HRC as a tradeoff since high hardness dies, while desirable for wear resistance, are prone to premature failure via thermal fatigue as the dies surface is rapidly cycled from 300C to 700C during aluminum production runs. 11 Figure 8. Hardness of artificially aged spray-formed H13 tool steel following one hour soaks at temperature. Hardness range of conventionally heat treated H13 included for comparison. As-deposited spray-formed material was also hardened following the conventional heat treatment cycle used with commercial material. Samples of forged/mill annealed commercial and spray- formed materials were austenitized at 1010C, air quenched, and double tempered (2 hr plus 2 hr) at (538C). The microstructure in both cases was found to be tempered martensite with a few spheroidal particles of alloy carbide. Hardness values for both materials were very nearly identical. Table 2 gives the ultimate tensile strength and yield strength of spray-formed, cast, and forged/heat treated H13 tool steel measured at test temperatures of 22 and 550C. Values for spray formed H13 are given in the as-deposited condition and following artificial aging and conventional heat treatments. Values for the spray-formed material are comparable to those of forged and are considerably higher than those of cast tool steel. The spray-formed material seems to retain its strength somewhat better than forged/heat treated H13 at higher temperatures. 12 Table 2. H13 tool steel mechanical properties. Sample/Heat Treatment Ultimate Tensile Strength (MPa) Yield Strength (MPa) Test Temperature (C) Spray formed/as-deposited 1061 951
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