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外文資料與中文翻譯
外文資料：
Analysis on The Factors of Impacting on The Life of Stamping Die
REN Hai-dong．YU Ling
Abstract：Stamping is a wide range of material processing methods，stamping die is equipment to achieve the important parts of theprocessing，whose life directly afects quality an d cost ofthe product．This article analyzes to its influencing factors，finding a method tosolveproblems，andimprovethelifeof stamping die．
Keywords：Samping die；life；Infl uencing facto
Is the use of stamping presses installed in the die pressure on the material to produce plastic deformation or separation in order to obtain the parts needed for a pressure processing method. In industrial production, especially in household appliances, automotive, aerospace and engineering fields such as instrumentation is widely available. The die is the realization of this important technology components and equipment for processing. Die as a result of a long cycle of production and processing, the use of the high cost of materials, manufacturing costs in product cost of production occupies a significant proportion, therefore, to improve the life of stamping dies is very important. Through the use of molds, for various reasons can not be a reproduction of the red pieces of qualified, could no longer be repaired, which is commonly referred to as die failure. Die life by various forms of limitations expired, common are: wear failure, failure deformation, fracture failure and failure, such as bite wounds. Stamping processes, as well as due to different working conditions of the different effects of stamping die failure are many factors, but the same factors may also bring some form of failure. In this paper, an analysis of its influencing factors, possible solutions to the problem in order to achieve the purpose of die life.
1 Mold Design
Mold design, including structural design and parts design. The structure of mold not only affects the quality of parts produced to determine the productivity of enterprises and processing methods, but also to improve the life of mold also has a key role. Therefore, before designers to make full preparations to meet the production tooling to optimize the structure at the same time.
1.1 Parts of Product Design
Reasonable product design will help improve the life of mold. If the product has a cusp, or fillet radius is too small, the design of the edge will die due to stress concentration and cracking. Without prejudice to the structure and function of products, we can change the design of some of its unreasonable.
1.2 Die Structure Design
Reasonable structure can improve the die life. For example, in Die, the direction to improve the convex and concave stamping die in the course of the relative stability, thus ensuring the mold space at a reasonable framework of blanking blanking. And the reasonableness of blanking clearance and stability to improve die life is an important measure. Accurate reduced-oriented relationship between the relative movement of the wear and tear of parts and components to avoid the convex, concave die as a result of unreasonable gap a "bite injuries" and other forms of failure. Particularly in the Fine Blanking Die, the high-precision mold-oriented institutions is to ensure that the structural design of an important guarantee for success. Therefore in order to improve the life of mold, the form must be the right choice and guide precision-oriented. The choice of orientation should be higher than the accuracy of convex and concave mold with precision. For more blanking punch, punch in a number of large difference in diameter, there is a difference and close the case that if a small and a long punch, then easily lead to instability or break. We can punch arranged in Figure 1 (a) ladder-style in order to increase its stiffness. Punching holes for the need to increase the punch guide in order to enhance the strength of punch, which is to ensure the normal work of stamping dies to the premise. Which can increase many-oriented approach, to be used in Figure 1 (b) shown in the front and the entire process-oriented and other-oriented.
Figure 1 (a) ladder layout punch 1 (b) punch-oriented
Accurate calculation of the process can also increase mold life. Such as discharge power and the calculation of stroke. If we are not allowed to easily spring fatigue fracture or failure. Die on a high degree of calculation, as well as the choice of press and reasonable manner and location-oriented institutions can effectively improve the die life. Modulus of continuity for the design and layout of the ride side of the calculation of size is also crucial.
1.3 Die gap
Stamping dies when space is the convex, concave die size difference between the horizontal edge. Gap on the impact of a large die life is a stamping process and die design of an extremely important issue. Convex, concave die gap size of a direct impact on product quality and mold the life space is too large or too small will cause the edge passivation or wear and tear (as shown in Figure 2). Die materials drop to die later, punch to punch prevail, and these two dimensions has been the impact of space. The experimental results show that the thickness of the gap below 2 percent, prone punch damage, space for more than 6%, there had been errors in parts size. Gap in the thickness of 4% ~ 5%, the effect of blanking good stability. Die gap, therefore the correct choice is to ensure that an important way to die life. At present, the choice of space data in addition to investigations, the most by the actual experience.
(a) gap is too small (b) a reasonable gap (c) gap is too large
Figure 2 gap on the impact of stampings
2 Die Manufacturing
Mold manufacturing process design is reasonable, to ensure that mold is an important way of life. Most of mold manufacturing parts of the process can be carried out in accordance with the normal, but there are special requirements for spare parts or spare parts for local processing, will need to have some special methods.
2.1 Mechanical Rough
Material machining accuracy of the assembly of the mold affects accuracy, it will directly affect the mold of parallelism, perpendicularity and coaxiality. In addition, the marks left rough, worn, are prone to stress concentration sites, but also occurred in the early fatigue cracks and the local.
2.2 Heat Treatment
Heat Treatment in the manufacture of stamping die plays a very important role, in spite of different types and different structure of mold, the use of different steel products, or using different machining and processing of shape, but they need to use heat treatment process to obtain a higher hardness and wear resistance, as well as other mechanical properties required. In general, the die service life and quality of products produced to a large extent depends on the quality of heat treatment processing. Thus, in die manufacturing, and continuously improve the skill level of heat treatment, a reasonable template to improve the performance of internal organization and working methods, it is particularly important. Heat treatment time and temperature is an important factor, because of the time in different temperatures, heat treatment may constitute a different form, the main annealing, normalizing, quenching and tempering, and carburizing, nitriding, carbonitriding, etc.. For example, in the blanking die, because people punch wedge material is the work of more serious wear and tear parts, so the hardness should be greater in general for the HRC 60 ~ 63, die for the HRC 57 ~ 60, this kind of hardness than the two , or die punch hardness is higher than the longer die life.
3 Die Assembly and Debugging
Assembly is the key to mold production process. A direct impact on the quality of the die assembly of the quality of parts, dies and the life of the state of the technology. Die assembly includes two aspects:
(1) good parts of each machining process in accordance with requirements of drawings assembled into a general assembly and assembly;
(2) in the assembly process as part of the processing work. Die in the assembly as an example, the technical requirements is to ensure consistency blanking gap and ensure the accuracy of direction-oriented institutions, as well as the movement to ensure that all relevant pieces of die design in accordance with strict technical parameters. This is a debugging tool to ensure a successful and smooth conduct of the production protection, but also to ensure that an important factor in mold life. In recent years, with the development of the production, users are vulnerable to damage parts of the swap request, so that users die at the scene of the rapid replacement of damaged parts. Die before the test mode, it should also be designed in strict accordance with the technical parameters of the model to select press. It is closely related to the length of die life. Press the stiffness, precision, crucial parameters such as tonnage. Press one of the stiffness of stiffness by the bed, transmission stiffness and rigidity of three parts-oriented, if less stiffness, load and unloading end, the die gap, great changes will happen, it will affect the accuracy of stamping parts and mold life. Die after assembly, must be red and adjust the test can be used for production. In order to protect the mold, the first time in debugging, it is necessary to pay attention to the use of paper or aluminum, as well as cold-rolled plate red test. To ensure that edge punch die edge into the depth of the scope of a reasonable (usually for a material thickness). Stamping die so red when the level of stress and wear and tear will be minimal, and fully protect the convex and concave mold, increased die life. The purpose of debugging and the task is: to die out not only qualified stampings, security and stability but also put into production use. Should be based on examination of stamping defects, analysis of its causes and try to solve them. Some bending, deep drawing and flanging, etc. so that the deformation of sheet metal dies, stamping parts, when the shape of complex or high accuracy, it is difficult to accurately calculate the deformation of the former size and shape of the rough. For this type of stamping parts, although the relevant references are rough calculation methods and formulas, but the impact of plastic deformation as a result of many factors, calculated from the size and needs of different size. In the actual production in order to obtain more accurate size, often determined through experiments. Red in the test set to adjust the size of blank.
4 Conclusion
Stamping die life impact of a number of factors, from the above analysis we can see from the mold design to the use of the entire process can improve the die life. Practice has proved that the rational design of die structure and the shape of the die using the appropriate manufacturing processes, heat treatment process, so that die in the normal conditions, can increase the mold life.
References:
[1] Weng its gold. Cold stamping technology [M]. Beijing: Mechanical Industry Press, 2007.
[2] Liu, ZHANG Bao-zhong. Stamping die design and manufacture of [M]. Beijing: Higher Education Publishing
Agency. 2006.
[3]Xiaopei.wang. Stamping Manual [M]. Beijing: Mechanical Industry Press, 2006.
中文翻譯：
影響沖壓模具壽命的因素分析
任海東，于玲
摘要：沖壓成形是一種應(yīng)用廣泛的材料加工方法，沖壓模具是實現(xiàn)零件加工的重要工藝裝備，它的使用壽命直接影響到產(chǎn)品的質(zhì)量和成本。對模具壽命的影響因素加以分析，找出解決問題的方法，從而達到提高模具壽命的目的。
關(guān)鍵詞：沖壓模具：壽命；影響因素
沖壓是利用安裝在壓力機上的沖模對材料施加壓力，使其產(chǎn)生分離或塑性變形，從而獲得所需要的零件的一種壓力加工方法。它在工業(yè)生產(chǎn)中，尤其是在家用電器、汽車、航空以及儀器儀表等工程領(lǐng)域獲得廣泛應(yīng)用。而沖模就是實現(xiàn)這一零件加工的重要工藝裝備。由于模具的生產(chǎn)加工周期長，使用的材料費用高，制造成本在產(chǎn)品生產(chǎn)成本中占有相當(dāng)大的比例，因此，提高沖壓模具的壽命是非常重要的。模具經(jīng)過使用，由于種種原因不能再生產(chǎn)出合格的沖件，也不能再修復(fù)，這種情況一般稱為模具失效。模具壽命受各種失效形式的限制，常見的有：磨損失效、變形失效、斷裂失效及啃傷失效等。由于沖壓工序不同以及工作條件的不同，影響沖壓模具失效的因素很多，而同一種因素也可能帶來幾種失效形式。本文對其影響因素進行分析，找出解決問題的方法，從而達到提高模具壽命的目的。
1 模具設(shè)計
模具設(shè)計包括結(jié)構(gòu)設(shè)計和零部件設(shè)計。模具的結(jié)構(gòu)不僅能影響到所生產(chǎn)零件的質(zhì)量，決定企業(yè)的生產(chǎn)效率和加工方式，而且對提高模具的使用壽命也具有關(guān)鍵的作用。因此設(shè)計者在設(shè)計之前，要做好充分的準備工作，在滿足生產(chǎn)的同時盡可能優(yōu)化模具結(jié)構(gòu)。
1．1 零件產(chǎn)品設(shè)計
合理的產(chǎn)品設(shè)計有利于提高模具的壽命。如果產(chǎn)品具有尖角，或圓角半徑太小，所設(shè)計的凹模刃口就會因應(yīng)力集中而開裂。在不影響產(chǎn)品結(jié)構(gòu)和功能的前提下，我們可以改變其一些不合理的設(shè)計。
1．2 模具結(jié)構(gòu)設(shè)計
合理的結(jié)構(gòu)可以提高模具的壽命。例如在沖裁模中，導(dǎo)向機構(gòu)提高了凸、凹模在沖壓過程中的相對穩(wěn)定性，從而保證模具在合理的沖裁間隙范圍內(nèi)進行沖裁。而沖裁間隙的合理性及穩(wěn)定性正是提高模具壽命的重要措施。精確的導(dǎo)向減少了有相對運動關(guān)系的零部件的磨損，避免了凸、凹模由于間隙不合理出現(xiàn)“啃傷”等失效形式。尤其在精密沖裁模中，高精度的
導(dǎo)向機構(gòu)是確保模具結(jié)構(gòu)設(shè)計成功的重要保障。因而為了提高模具的壽命，必須正確選擇導(dǎo)向形式和導(dǎo)向精度。導(dǎo)向精度的選擇應(yīng)高于凸、凹模的配合精度。對于多凸模沖裁，在幾個凸模直徑相差較大，相距又很近的情況下，如果小凸模細小而又較長，則容易造成失穩(wěn)或折斷。我們可以把凸模布置成如圖1(a)階梯式的，以增加其剛度。對于小孔沖裁，必須增加對凸模的導(dǎo)向，以提高凸模的強度，這是保證沖壓模具能正常工作的前提。其中能增加導(dǎo)向的方法很多，可采用如圖1(b)所示的前端導(dǎo)向和全程導(dǎo)向等。
準確的工藝計算也可以提高模具的壽命。如卸料力及行程的計算。若計算不準，容易造成彈簧的疲勞斷裂或失效。對合模高度的計算以及壓力機的選擇，合理的定位方式及導(dǎo)向機構(gòu)等，都可以有效地提高模具的使用壽命。對于連續(xù)模排樣的設(shè)計和搭邊尺寸的計算也至關(guān)重要。
1．3 模具間隙
模具間隙是指沖壓時凸、凹模刃口橫向尺寸之差。間隙對模具壽命的影響很大，是沖壓工藝與模具設(shè)計中的一個極其重要的問題。凸、凹模間隙的大小直接影響產(chǎn)品的質(zhì)量和模具的使用壽命，間隙過大或過小都會使刃口鈍化或磨損(如圖2所示)。沖裁模中落料一般以凹模為準，沖孔以凸模為準，而這兩個尺寸又受到間隙的影響。實驗表明，間隙在板厚的2％以下時，凸模容易發(fā)生損壞，間隙在6％以上時，制件尺寸出現(xiàn)誤差。間隙在板厚4％ ～5％時，沖裁穩(wěn)定效果好。因此正確選擇模具間隙，是保證模具壽命的重要途徑。目前，間隙的選擇除了查資料以外，大部分靠實際經(jīng)驗獲得。
2 模具制造
模具制造工藝設(shè)計的合理性，也是保證模具壽命的重要途徑。大部分模具零件的制造可以按正常的工藝進行，但對有特別要求的零件或零件局部加工，就需要有一定特殊的方法。
2．1 機械粗加工
材料的加工精度對模具的裝配精度有很大的影響，將直接影響模具的平行度、垂直度和同軸度。另外，粗加工留下的刀痕、磨痕，都是容易產(chǎn)生應(yīng)力集中的部位，也是早期產(chǎn)生裂紋和發(fā)生疲勞的地方。
2．2 熱處理
熱處理在沖壓模具的制造中起著很重要的作用，盡管不同類型及不同的結(jié)構(gòu)模具，使用不同的鋼材，或采用不同的機械加工及加工成形，但都需要用熱處理的加工方法，使其獲得較高的硬度和耐磨性，以及其他所要求的力學(xué)性能。一般來說，沖模的使用壽命及生產(chǎn)出來的產(chǎn)品質(zhì)量，在很大程度上取決于熱處理加工質(zhì)量．因此，在沖模制造中，不斷提高熱處理的技術(shù)水平，合理的改進模板內(nèi)部組織和性能的工作方法，就顯得格外的重要。時間和溫度是熱處理的重要因素，由于時間溫度的不同，可構(gòu)成不同的熱處理形式，其主要有退火、正火、淬火、回火和滲碳、滲氮、碳氮共滲等。比如在沖裁模中，由于凸模楔人材料，是磨損比較嚴重的工作零件，所以其硬度應(yīng)大些，一般為HRC 60～63，凹模為HRC 57～60，這樣比兩者硬度樣，或凹模硬度高于凸模的模具壽命更長一些。
3 模具裝配及調(diào)試
裝配是模具生產(chǎn)中的關(guān)鍵工序。沖模裝配質(zhì)量直接影響制件的質(zhì)量、沖模的技術(shù)狀態(tài)和使用壽命。沖模的裝配工作包括兩方面的內(nèi)容：
(1)將每個加工好的零件按圖紙工藝要求裝配成組合件及總體裝配；
(2)在裝配過程中進行的一部分加工工作。以沖裁模的裝配為例，其技術(shù)要求是保證沖裁間隙一致性，保證導(dǎo)向機構(gòu)的導(dǎo)向精度，以及保證各相關(guān)運動件能夠按照模具設(shè)計的技術(shù)參數(shù)嚴格進行。這是保證模具調(diào)試成功及生產(chǎn)能夠順利進行的保障，也是確保模具壽命的重要因素。近年來，隨著生產(chǎn)的發(fā)展，用戶對易損壞零件提出了互換要求，以便用戶在現(xiàn)場對模具損壞零件的迅速更換。模具在試模前，還應(yīng)該嚴格按照設(shè)計的技術(shù)參數(shù)來選擇壓力機的型號。它關(guān)系到模具使用壽命的長短。壓力機的剛度、精度、噸位等參數(shù)至關(guān)重要。其中壓力機的剛度是由床身剛度、傳動剛度和導(dǎo)向剛度三部分組成，如果剛度較差，負載終了和卸載時，模具間隙會發(fā)生很大變化，將會影響到?jīng)_壓件的精度和模具壽命。模具裝配完后，必須經(jīng)過試沖和調(diào)整，才能進行生產(chǎn)使用。為了保護模具，在第一次調(diào)試時，要注意利用紙片或鋁片以及冷軋板進行試沖。保證凸模刃口進入到凹模刃口的深度在合理的范圍內(nèi)(一般為一個料厚)。這樣模具沖壓時的沖壓力及磨損程度會最小，充分保護了凸、凹模，提高了模具壽命。調(diào)試的目的和任務(wù)是：使沖模不僅能沖出合格的沖壓件，而且能安全穩(wěn)定的投入生產(chǎn)使用。應(yīng)根據(jù)試沖件中出現(xiàn)的缺陷，分析其產(chǎn)生的原因，設(shè)法加以解決。有些彎曲、拉深及翻邊等使板料變形的沖模，當(dāng)沖壓件的形狀復(fù)雜或精度較高時，很難精確計算出變形前的毛坯尺寸和形狀。對于這一類沖壓件，雖然相關(guān)參考資料都有計算毛坯的方法和公式，但由于影響塑性變形的因素非常多，計算出來的尺寸和實際的需要尺寸是有差別的。在實際的生產(chǎn)中為了得到較準確的尺寸，往往通過試驗來確定．即在試沖調(diào)整中確定毛坯的尺寸。
4 結(jié)論
影響沖壓模具壽命的因素很多，從以上分析可以看出從模具設(shè)計到使用的全過程中，均能提高模具壽命。實踐證明，合理設(shè)計模具結(jié)構(gòu)及形狀，采用恰當(dāng)?shù)臎_模制造工藝、熱處理工藝，使模具在正常的條件下工作，均能提高模具的壽命。
參考文獻：
[1]翁其金．冷沖壓技術(shù)[M]．北京：機械工業(yè)出版社，2007．
[2]劉建超，張寶忠．沖壓模具設(shè)計與制造[M]．北京：高等教育出版
社。2006．
[3]王孝培．沖壓手冊[M]．北京：機械工業(yè)出版社，2006．
14
沖壓成形與板材沖壓
1． 概述
通過模具使板材產(chǎn)生塑性變形而獲得成品零件的一次成形工藝方法叫做沖壓。由于沖壓通常在冷態(tài)下進行，因此也稱為冷沖壓。只有當(dāng)板材厚度超過8~100mm時，才采用熱沖壓。沖壓加工的原材料一般為板材或帶材，故也稱板材沖壓。某些非金屬板材（如膠木板、云母片、石棉、皮革等）亦可采用沖壓成形工藝進行加工。
沖壓廣泛應(yīng)用于金屬制品各行業(yè)中，尤其在汽車、儀表、軍工、家用電器等工業(yè)中占有極其重要的地位。沖壓成形需研究工藝設(shè)備和模具三類基本問題。
? 板材沖壓具有下列特點：
（1）．高的材料利用率。
（2）．可加工薄壁、形狀復(fù)雜的零件。
（3）．沖壓件在形狀和尺寸方面的互換性好。
（4）．能獲得質(zhì)量輕而強度高、剛性好的零件。
（5）．生產(chǎn)率高，操作簡單，容易實現(xiàn)機械化和自動化。
沖壓模具制作成本高，因此適合大批量生產(chǎn)。對于小批量、多品種生產(chǎn)，常采用簡易沖模，同時引進沖壓加工中心等新型設(shè)備，以滿足市場求新求變的需求。板材沖壓常用的金屬材料有低碳鋼、銅、鋁、鎂合金及高塑性的合金剛等。如前所述，材料形狀有板材和帶材。
沖壓生產(chǎn)設(shè)備有剪床和沖床。剪床是用來將板材剪切成具有一定寬度的條料，以供后續(xù)沖壓工序使用，沖床可用于剪切及成形。
2． 沖壓成形的特點
生產(chǎn)時間中所采用的沖壓成形工藝方法有很多，具有多種形式餓名稱，但塑性變形本質(zhì)是相同的。沖壓成形具有如下幾個非常突出的特點。
（1）．垂直于板面方向的單位面積上的壓力，其數(shù)值不大便足以在板面方向上使??板材產(chǎn)生塑性變形。由于垂直于板面方向上的單位面積上壓力的素質(zhì)遠小于板面方向上的內(nèi)應(yīng)力，所以大多數(shù)的沖壓變形都可以近似地當(dāng)作平面應(yīng)力狀態(tài)來處理，使其變形力學(xué)的分析和工藝參數(shù)的計算大呢感工作都得到很大的簡化。
（2）．由于沖壓成形用的板材毛胚的相對厚度很小，在壓應(yīng)力作用下的抗失穩(wěn)能力也很差，所以在沒有抗失穩(wěn)裝置（如壓邊圈等）的條件下，很難在自由狀態(tài)下順利地完成沖壓成形過程。因此，以拉應(yīng)力作用為主的伸長類沖壓成形過程多于以壓應(yīng)力作用為主的壓縮類成形過程。
（3）．沖壓成形時，板材毛胚內(nèi)應(yīng)力的數(shù)值等于或小于材料的屈服應(yīng)力。在這一點上，沖壓成形與體積成形的差別很大。因此，在沖壓成形時變形區(qū)應(yīng)力狀態(tài)中的靜水壓力成分對成形極限與變形抗力的影響，已失去其在體積成形時的重要程度，有些情況下，甚至可以完全不予考慮，即使有必要考慮時，其處理方法也不相同。
（4）．在沖壓成形時，模具對板材毛胚作用力所形成的約束作用較輕，不像體積成形（如模鍛）是靠與制件形狀完全相同的型腔對毛胚進行全面接觸而實現(xiàn)的強制成形。在沖壓成形中，大多數(shù)情況下，板材毛胚都有某種程度的自由度，常常是只有一個表面與模具接觸，甚至有時存在板材兩側(cè)表面都有于模具接觸的變形部分。在這種情況下，這部分毛胚的變形是靠模具對其相鄰部分施加的外力實現(xiàn)其控制作用的。例如，球面和錐面零件成形時的懸空部分和管胚端部的卷邊成形都屬這種情況。
? ?由于沖壓成形具有上述一些在變形與力學(xué)方面的特點，致使沖壓技術(shù)也形成了一些與體積成形不同的特點。由于不需要在板材毛的表面施加很大的單位壓力即可使其成形，所以在沖壓技術(shù)中關(guān)于模具強度與剛度的研究并不十分重要，相反卻發(fā)展了學(xué)多簡易模具技術(shù)。
由于相同原因，也促使靠氣體或液體壓力成形的工藝方法得以發(fā)展。因沖壓成形時的平面應(yīng)力狀態(tài)或更為單純的應(yīng)變狀態(tài)（與體積成形相比），當(dāng)前對沖壓成形匯中毛胚的變形與 力能參數(shù)方面的研究較為深入，有條件運用合理的科學(xué)方法進行沖壓加工。借助于電子計算機與先進的測試手段，在對板材性能與沖壓變形參數(shù)進行實時測量與分析基礎(chǔ)上，實現(xiàn)沖壓過程智能化控制的研究工作也在開展。人們在對沖壓成形過程有離開較為深入的了解后，已經(jīng)認識到?jīng)_壓成型與原材料有十分密切的關(guān)系。所以，對板材沖壓性能即成形性與形狀穩(wěn)定性的研究，目前已成為沖壓技術(shù)的一個重要內(nèi)容。對板材沖壓性能的研究工作不僅是沖壓技術(shù)發(fā)展的需要，而且也促進了鋼鐵工業(yè)生產(chǎn)技術(shù)的發(fā)展，為其提高板材的質(zhì)量提供了一個可靠的基礎(chǔ)與依據(jù)。
3．沖壓變形的分類
? ?沖壓變形工藝可完成多種工序，其基本工序可分為分離工序和變形工序兩大類。分離工序是使胚料的一部分與另一部分相互分離的工藝方法，主要有落料、沖孔、切邊、剖切、修整等。其中又以沖孔、落料應(yīng)用最廣。變形工序是使胚料的一部分相對于另一部分產(chǎn)生位移而不破裂的工藝方法，主要有拉深、彎曲、局部成形、脹形、翻邊、縮徑、校形、旋壓等。
從本質(zhì)上看，沖壓成形就是毛胚的變形區(qū)在外力的作用下產(chǎn)生相應(yīng)的塑性變形，所以變形區(qū)內(nèi)的應(yīng)力狀態(tài)和變形特點景象的沖壓成形分類，可以把成形性質(zhì)相同的成形方法概括成同一個類型并進行體系化的研究。
絕大多數(shù)沖壓成形時毛胚變形區(qū)均處于平面應(yīng)力狀態(tài)。通常認為在板材表面上不受外力的作用，即使有外力作用，其數(shù)值也是較小的，所以可以認為垂直于板面方向上的應(yīng)力為零，使板材毛胚產(chǎn)生塑性變形的是作用于板面方向上相互的兩個主應(yīng)力。由于板厚較小，通常都近似地認為這兩個主應(yīng)力在厚度方向上是均勻分布的?；谶@樣的分析，可以把各種形式?jīng)_壓成型中的毛陪變形區(qū)的受力狀態(tài)與變形特點，在平面應(yīng)力的應(yīng)力坐標(biāo)系中與相應(yīng)的兩向應(yīng)變坐標(biāo)系中以應(yīng)力與應(yīng)變坐標(biāo)決定的位置來表示。
4.沖壓用原材料
? ?沖壓加工用原材料有很多種，它們的性能也有很大的差別，所以必須根據(jù)原材料的性能與特點，采用不同的沖壓成形方法、工藝參數(shù)和模具結(jié)構(gòu)，才能達到?jīng)_壓加工的目的。由于人們對沖壓成形過程板材毛胚的變形行為有了較為深入的認識，已經(jīng)相當(dāng)清楚的建立了由原材料的化學(xué)成分、組織等因素所決定的材料性能與沖壓成形之間的關(guān)系，這就使原材料生產(chǎn)部門不但按照沖壓件的工作條件與使用要求進行原材料的設(shè)計工作，而且也根據(jù)沖壓件加工過程對板材性能的要求進行新型材料的開發(fā)工作，這是沖壓技術(shù)在原材料研究方面的一個重要方向。對沖壓用原材料沖壓性能方面的研究工作有
（1）原材料沖壓性能的含義。
（2）判斷原材料沖壓性能的科學(xué)方法，確定可以確切反映材料沖壓性能的參數(shù)，建立沖壓性能的參數(shù)與實際沖壓成形間的關(guān)系，以及沖壓性能參數(shù)的測試方法等。
（3）建立原材料的化學(xué)成分、組織和制造過程與沖壓性能之間的關(guān)系。沖壓用原材料主要是各種金屬與非金屬板材。金屬板材包括各種黑色技術(shù)和有色金屬板材。雖然在沖壓生產(chǎn)中所用金屬板材的種類很多，但最多的原材料蛀牙是鋼板、不銹鋼板、鋁合金板及各種復(fù)合金屬板。
5．板材沖壓性能及其鑒定方法
? ? 板材是指對沖壓加工的適應(yīng)能力。對板材沖壓性能的研究具有飛行重要的意義。為了能夠運用最科學(xué)與最經(jīng)濟合理的沖壓工藝過程與工藝參數(shù)制造出沖壓零件，必須對作為加工對象的板材的性能具有十分清楚的了解，這樣才有可能充分地利用板材在加工方面的潛在能力。另一方面，為了能夠依據(jù)沖壓件的形狀與尺寸特點及其所需的成形工藝等基本因素，正確、合理地選用板材，也必須對板材的沖壓性能有一個科學(xué)的認識與正確的判斷。評定板材沖壓性能的方法有直接試驗法與間接試驗法。
? ?實物沖壓試驗是最直接的板材沖壓性能的評定方法。利用實際生產(chǎn)設(shè)備與模具，在與生產(chǎn)完全相同的條件下進行實際沖壓零件的性能評定，當(dāng)然能夠的最可靠的結(jié)果。但是，這種評定方法不具有普遍意義，不能作為行業(yè)之間的通用標(biāo)準進行信息的交流。
? ?模擬試驗是把生產(chǎn)中實際存在的沖壓成形方法進行歸納與簡單化處理，消除許多過于復(fù)雜的因素，利用軸對稱的簡化了的成形方法，在保證試驗中板材的變形性質(zhì)與應(yīng)力狀態(tài)都與實際沖壓成形相同的條件下進行的沖壓性能的評定工作。為了保證模擬試驗結(jié)果的可靠性與通用性，規(guī)定了私分具體的關(guān)于試驗用工具的幾何形狀與尺寸、毛胚的尺寸、試驗條件（沖壓速度、潤滑方法、壓邊力等）。
? ?間接試驗法也叫做基礎(chǔ)試驗法。間接試驗法的特點是：在對板材在塑性變形過程中所表現(xiàn)出的基本性質(zhì)與規(guī)律進行分析與研究的基礎(chǔ)上，進一步把它和具體的沖壓成形中板材的塑性變形參數(shù)聯(lián)系起來，建立間接試驗結(jié)果（間接試驗值）與具體的沖壓成形性能（工藝參數(shù)）之間的相關(guān)性。由于間接試驗時所用試件的形狀與尺寸以及加載的方式等都不同于具體的沖壓成形過程，所以它的變形性質(zhì)和應(yīng)力狀態(tài)也不同于沖壓變形。因此間接試驗所得的結(jié)果（試驗值）并不是沖壓成形的工藝參數(shù)，而是可以用來表示板材沖壓性能的基礎(chǔ)性參數(shù)。
Characteristics and Sheet Metal Forming
1． The article overview
Stamping is a kind of plastic forming process in which a part is produced by means of the plastic forming the material under the action of a die. Stamping is usually carried out under cold state, so it is also called stamping. Heat stamping is used only when the blank thickness is greater than 8~100mm. The blank material for stamping is usually in the form of sheet or strip, and therefore it is also called sheet metal forming. Some non-metal sheets (such as plywood, mica sheet, asbestos, leather)can also be formed by stamping.
?? Stamping is widely used in various fields of the metalworking industry, and it plays a crucial role in the industries for manufacturing automobiles, instruments, military parts and household electrical appliances, etc.
? ?The process, equipment and die are the three foundational problems that needed to be studied in stamping.
? ?The characteristics of the sheet metal forming are as follows:
(1)? ? High material utilization
(2)? ? Capacity to produce thin-walled parts of complex shape.
(3)? ? Good interchangeability between stamping parts due to precision in shape??
and dimension.
(4)? ? Parts with lightweight, high-strength and fine rigidity can be obtained.
(5)? ? High productivity, easy to operate and to realize mechanization and? ? automatization.
? ? The manufacture of the stamping die is costly, and therefore it only fits to mass production. For the manufacture of products in small batch and rich variety, the simple stamping die and the new equipment such as a stamping machining center, are usually adopted to meet the market demands. The materials for sheet metal stamping include mild steel, copper, aluminum, magnesium alloy and high-plasticity alloy-steel, etc.??
Stamping equipment includes plate shear punching press. The former shears plate into strips with a definite width, which would be pressed later. The later can be used both in shearing and forming.
2．Characteristics of stamping forming
There are various processes of stamping forming with different working patterns and names. But these processes are similar to each other in plastic deformation. There are following conspicuous characteristics in stamping:
（1）．The force per unit area perpendicular to the blank surface is not large but is enough to cause the material plastic deformation. It is much less than the inner stresses on the plate plane directions. In most cases stamping forming can be treated approximately as that of the plane stress state to simplify vastly the theoretical analysis and the calculation of the process parameters.
（2）．Due to the small relative thickness, the anti-instability capability of the blank is weak under compressive stress. As a result, the stamping process is difficult to proceed successfully without using the anti-instability device (such as blank holder). Therefore the varieties of the stamping processes dominated by tensile stress are more than dominated by compressive stress.
（3）．During stamping forming, the inner stress of the blank is equal to or sometimes less than the yield stress of the material. In this point, the stamping is different from the bulk forming. During stamping forming, the influence of the hydrostatic pressure of the stress state in the deformation zone to the forming limit and the deformation resistance is not so important as to the bulk forming. In some circumstances, such influence may be neglected. Even in the case when this influence should be considered, the treating method is also different from that of bulk forming.
（4）．In stamping forming, the restrain action of the die to the blank is not severs as in the case of the bulk forming (such as die forging). In bulk forming, the constraint forming is proceeded by the die with exactly the same shape of the part. Whereas in stamping, in most cases, the blank has a certain degree of freedom, only one surface of the blank contacts with the die. In some extra cases, such as the forming of the blank on the deforming zone contact with the die. The deformation in these regions are caused and controlled by the die applying an external force to its adjacent area.
Due to the characteristics of stamping deformation and mechanics mentioned above, the stamping technique is different form the bulk metal forming: The importance or the strength and rigidity of the die in stamping forming is less than that in bulk forming because the blank can be formed without applying large pressure per unit area on its surface. Instead, the techniques of the simple die and the pneumatic and hydraulic forming are developed.
Due to the plane stress or simple strain state in comparison with bulk forming, more research on deformation or force and power parameters has been done. Stamping forming can be performed by more reasonable scientific methods. Based on the real time measurement and analysis on the sheet metal properties and stamping parameters, by means of computer and some modern testing apparatus, research on the intellectualized control of stamping process is also in proceeding. It is shown that there is a close relationship between stamping forming and raw material. The research on the properties of the stamping forming, that is, forming ability and shape stability, has become a key point in stamping technology development, but also enhances the manufacturing technique of iron and steel industry, and provides a reliable foundation for increasing sheet metal quality.
3．Categories of stamping forming
? ? Many deformation processes can be done by stamping, the basic processes of the stamping can be divided into two kinds: cutting and forming.Cutting is a shearing process that one part of the blank is cut from the other. It mainly includes blanking, punching, trimming, parting and shaving, where punching and blanking are the most widely used. Forming is a process that one part of the blank has some displacement from the other. It mainly includes deep drawing, bending, local forming, bulging, flanging, necking, sizing and spinning.
In substance, stamping forming is such that the plastic deformation occurs in the deformation zone of the stamping blank caused by the external force. The stress state and deformation characteristic of the deformation zone are the basic factors to decide the properties of the stamping forming. Based on the stress state and deformation characteristics of the deformation zone, the forming methods can be divided into several categories with the same forming properties and be studied systematically.
??The deformation zone in almost all types of stamping forming is in the plane stress state. Usually there is no force or only small force applied on the blank surface. When is assumed that the stress perpendicular to the blank surface equals to zero, two principal stresses perpendicular to each other and act on the blank surface produce the plastic deformation of the material. Due to the small thickness of the blank, it is assumed approximately the two principal stresses distribute uniformly along the thickness direction. Based on this analysis, the stress state and the deformation characteristics of the deformation zone in all kinds of stamping forming can be denoted by the points in the coordinates of the plane principal stresses and the coordinates of the corresponding plane principal strains.
4．Raw materials for stamping forming
There are a lot of raw materials used in stamping forming, and the properties of these materials may have large difference. The stamping forming can be succeeded only by determining the stamping method, the forming parameters and the die structures according to the properties and characteristics of the raw materials. The deformation of the blank during stamping forming has been investigated quite thoroughly. The relationships between the material properties decided by the chemistry component and structure of the material and the stamping forming has been established clearly. Not only the proper material can be selected based on the working condition and usage demand, but also the new material can be developed according to the demands of the blank properties during processing the stamping part. This is an important domain in stamping forming research. The research on the material properties for stamping forming is as follows:
（1）．Definition of the stamping property of the material.
（2）．Method to judge the stamping property of the material, find parameters to express the definitely material property of the stamping forming, establish the relationship between the property parameters and the practical stamping forming, and investigate the testing methods of the property parameters.
（3）．Establish the relationship among the chemical component, structure, manufacturing process and stamping property.
?? The raw materials for stamping forming mainly include various metals and nonmetal plate. Sheet metal includes both ferrous and nonferrous metals. Although a lot of sheet metals are used in stamping forming, the most widely used materials are steel, stainless steel, aluminum alloy and various composite metal plates.
5．Stamping forming property of sheet metal and its assessing method
The stamping forming property of the sheet metal is the adaptation capability of the sheet metal to stamping forming. It has crucial meaning to the investigation of the stamping forming property of the sheet metal. In order to produce stamping forming parts with most scientific, economic and rational stamping forming process and forming parameters, it is necessary to understand clearly the properties of the sheet metal, so as to utilize the potential of the sheet metal fully in the production. On the other hand, to select plate material accurately and rationally in accordance with the characteristics of the shape and dimension of the stamping forming part and its forming technique is also necessary so that a scientific understanding and accurate judgment to the stamping forming properties of the sheet metal may be achieved.
There are direct and indirect testing methods to assess the stamping property of the sheet metal?.Practicality stamping test is the most direct method to assess stamping forming property of the sheet metal. This test is done exactly in the same condition as actual production by using the practical equipment and dies. Surely, this test result is most reliable. But this kind of assessing method is not comprehensively applicable, and cannot be shared as a commonly used standard between factories.
? ? The simulation test is a kind of assessing method that after simplifying and summing up actual stamping forming methods, as well as eliminating many trivial factors, the stamping properties of the sheet metal are assessed, based on simplified axial-symmetric forming method under the same deformation and stress states between the testing plate and the actual forming states. In order to guarantee the reliability and generality of simulation results, a lot of factors are regulated in detail, such as the shape and dimension of tools for test, blank dimension and testing conditions(stamping velocity, lubrication method and blank holding force, etc).???Indirect testing method is also called basic testing method its characteristic is to connect analysis and research on fundamental property and principle of the sheet metal during plastic deformation, and with the plastic deformation parameters of the sheet metal in actual stamping forming, and then to establish the relationship between the indirect testing results(indirect testing value) and the actual stamping forming property (forming parameters). Because the shape and dimension of the specimen and the loading pattern of the indirect testing are different from the actual stamping forming, the deformation characteristics and stress states of the indirect test are different from those of the actual one. So, the results obtained form the indirect test are not the stamping forming parameters, but are the fundamental parameters that can be used to represent the stamping forming property of the sheet metal.