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邵陽學院畢業(yè)設計(論文)
工藝規(guī)程制訂與機械設計
產品設計是用于產品,及它的部件裝配的計劃. 為了把產品設計轉換成一個實際物體 ,這需要一個制造計劃。而制訂一個這樣的計劃的行動就叫做工藝規(guī)程制訂。它是產品設計和制造之間的連接.工藝規(guī)程制訂包括決定加工順序和制造產品所必須完成的裝配步驟.在以下文章中,我們將解釋工藝規(guī)程制訂和他的一些相關主題。
文章開始, 我們應該區(qū)別在下列文章中被反復提到的工藝規(guī)程制訂和生產計劃。工藝規(guī)程制訂與如何制造產品和它的零件等工程技術問題有關.制造零件和裝配產品需要什么樣的設備和工具? 工藝規(guī)程制訂與產品制造物流管理有關系。它在工藝規(guī)程制訂后面與原料分類及獲得滿足制造充分數量產品要求的資源有關.
工藝規(guī)程制訂包括決定最適當的制造及裝配步驟和順序,在這些順序和步驟中他們必須根據所提出的詳細的設計說明書規(guī)范完成給定零件或產品制造. 能夠被計劃的工藝范圍和多樣性通常由于公司車間可用設備和技術能力而受到限制.在公司內部不能夠制造的零件必須到外部市場購買. 工藝規(guī)程制訂所提及的工藝選擇同樣也受到詳細設計資料的限制.我們稍后將會回到這一點.
工藝規(guī)程制訂通常是由制造工程師完成的.( 工業(yè)工程師擁有其他權利.) 工藝制訂者必須熟悉工廠中詳細可用的制造流程并且能夠說明工程圖。基于制訂者的知識,技術和經驗, 用于制造每個零件的工藝步驟以最合乎邏輯的順序被發(fā)展制訂。下列各項是在工藝規(guī)程制訂范圍里的許多決定和詳細資料:
設計圖的說明 在工藝規(guī)程制訂的開始,產品設計的這一部分( 材料,尺寸,公差 ,表面處理,等等)必須進行分析。
工藝和順序 工藝制訂者必須選擇哪一個工藝是必需的及必需工藝的序列。此外還必須準備好一個簡短的工藝步驟描述.
設備選擇 大體上,工藝制訂者必須逐步展開利用工廠現有機器的計劃.另外,組件必須被購買或在新設備上的投資必須被制定.
工具,沖模,鑄模,夾具,量具工藝必須決定每個工序需要什么工具.這些工具的實際設計和制造通常通過委派工具設計部門和工具庫或者聯(lián)系專攻那種工具制造的外面廠商來完成.
方法分析 車間規(guī)劃,小工具,提升重物的提升間,甚至在一些人工操作情景中的肢體動作也被指定.
操作步驟 工作測量技術被用來為每個操作設定時間標準。
切削工具和切削條件 這些必須對加工操作通過推薦標準手冊來進行詳細說明.
對于單個零件,加工順序通過一種被稱為進路表的表格來進行文件證明備份. ( 不是所有的公司使用進路表這個名字;另外的一個名字是 " 操作說明書?!?就如工程圖被用于詳細說明設計產品一樣,進路表被用于詳細說明工藝計劃. 他們是類似的, 一個用于產品設計 , 另一個用于制造。
機械設計是一門通過設計新產品或者改進老產品來滿足人類需求的應用技術科學。它涉及工程技術的各個領域,主要研究產品的尺寸、形狀和詳細結構的基本構思,還要研究產品在制造、銷售和使用等方面的問題。
進行各種機械設計工作的人員通常被稱為設計人員或者機械設計工程師。機械設計是一項創(chuàng)造性的工作。設計工程師不僅在工作上要有創(chuàng)造性,還必須在機械制圖、運動學、工程材料、材料力學和機械制造工藝學等方面具有深厚的基礎知識。
如前所訴,機械設計的目的是生產能夠滿足人類需求的產品。發(fā)明、發(fā)現和科技知識本身并不一定能給人類帶來好處,只有當它們被應用在產品上才能產生效益。因而,應該認識到在一個特定的產品進行設計之前,必須先確定人們是否需要這種產品。
應當把機械設計看成是機械設計人員運用創(chuàng)造性的才能進行產品設計、系統(tǒng)分析和制定產品的制造工藝學的一個良機。掌握工程基礎知識要比熟記一些數據和公式更為重要。僅僅使用數據和公式是不足以在一個好的設計中做出所需的全部決定的。另一方面,應該認真精確的進行所有運算。例如,即使將一個小數點的位置放錯,也會使正確的設計變成錯誤的。
一個好的設計人員應該勇于提出新的想法,而且愿意承擔一定的風險,當新的方法不適用時,就使用原來的方法。因此,設計人員必須要有耐心,因為 所花費的時間和努力并不能保證帶來成功。一個全新的設計,要求屏棄許多陳舊的,為人們所熟知的方法。由于許多人墨守成規(guī),這樣做并不是一件容易的事。一位機械設計師應該不斷地探索改進現有的產品的方法,在此過程中應該認真選擇原有的、經過驗證的設計原理,將其與未經過驗證的新觀念結合起來。
新設計本身會有許多缺陷和未能預料的問題發(fā)生,只有當這些缺陷和問題被解決之后,才能體現出新產品的優(yōu)越性。因此,一個性能優(yōu)越的產品誕生的同時,也伴隨著較高的風險。應該強調的是,如果設計本身不要求采用全新的方法,就沒有必要僅僅為了變革的目的而采用新方法。
在設計的初始階段,應該允許設計人員充分發(fā)揮創(chuàng)造性,不受各種約束。即使產生了許多不切實際的想法,也會在設計的早期,即繪制圖紙之前被改正掉。只有這樣,才不致于堵塞創(chuàng)新的思路。通常,要提出幾套設計方案,然后加以比較。很有可能在最后選定的方案中,采用了某些未被接受的方案中的一些想法。
心理學家經常談論如何使人們適應他們所操作的機器。設計人員的基本職責是努力使機器來適應人們。這并不是一項容易的工作,因為實際上并不存在著一個對所有人來說都是最優(yōu)的操作范圍和操作過程。
通常 ,在制造過程中會出現某個問題??赡軙髮δ硞€零件尺寸或公差作一些更改,使零件的生產變得容易。但是,工程上的更改必須要經過設計人員批準,以保證不會損傷產品的功能。有時,在產品的裝配時或者裝箱外運前的試驗中才發(fā)現設計中的某種缺陷。這些事例恰好說明了設計是一個動態(tài)過程??偸谴嬖谥玫姆椒▉硗瓿稍O計工作,設計人員應該不斷努力,尋找這些更好的方法。
近些年來,工程材料的選擇已經顯得重要。此外,選擇過程應該是一個對材料的連續(xù)不斷的重新評價過程。新材料不斷出現,而一些原有的材料的能夠獲得的數量可能會減少。環(huán)境污染、材料的回收利用、工人的健康及安全等方面經常會對材料選擇附加新的限制條件。為了減輕重量或者節(jié)約能源,可能會要求使用不同的材料。來自國內和國際競爭、對產品維修保養(yǎng)方便性要求的提高和顧客的反饋等方面的壓力,都會促使人們對材料進行重新評價。由于材料選用不當造成的產品責任訴訟,已經產生了深刻的影響。此外,材料與材料加工之間的相互依賴關系已經被人們認識得更清楚。因此,為了能在合理的成本和確保質量的前提下獲得滿意的結果,設計工程師的制造工程師都必須認真仔細地選擇、確定和使用材料。
制造任何產品的第一步工作都是設計。設計通常可以分為幾個明確的階段:(a)初步設計;(b)功能設計;(c)生產設計。在初步設計階段,設計者著重考慮產品應該具有的功能。通常要設想和考慮幾個方案,然后決定這種思想是否可行;如果可行,則應該對其中一個或幾個方案作進一步的改進。在此階段,關于材料選擇唯一要考慮的問題是:是否有性能符合要求的材料可供選擇;如果沒有的話,是否有較大的把握在成本和時間都允許的限度內研制出一種新材料。
在功能設計和工程設計階段,要做出一個切實可行的設計。在這個階段要繪制出相當完整的圖紙,選擇并確定各種零件的材料。通常要制造出樣機或者實物模型,并對其進行試驗,評價產品的功能、可靠性、外觀和維修保養(yǎng)性等。雖然這種試驗可能會表明,在產品進入到生產階段之前,應該更換某些材料,但是,絕對不能將這一點作為不認真選擇材料的借口。應該結合產品的功能,認真仔細地考慮產品的外觀、成本和可靠性。一個很有成就的公司在制造所有的樣機時,所選用的材料應該和其生產中使用的材料相同,并盡可能使用同樣的制造技術。這樣對公司是很有好處的。功能完備的樣機如果不能根據預期的銷售量經濟地制造出來,或者是樣機與正式生產的裝置在質量和可靠性方面有很大不同,則這種樣機就沒有多大的價值。設計工程師最好能在這一階段完全完成材料的分析、選擇和確定工作,而不是將其留到生產設計階段去做。因為,在生產設計階段材料的更換是由其他人進行的,這些人對產品的所有功能的了解不如設計工程師。
在生產設計階段中,與材料有關的主要問題是應該把材料完全確定下來,使它們與現有的設備相適應,能夠利用現有設備經濟地進行加工,而且材料的數量能夠比較容易保證供應。
在制造過程中,不可避免地會出現對使用中的材料做一些更改的情況。經驗表明,可采用某些便宜材料作為替代品。然而,在大多數情況下,在進行生產以后改換材料要比在開始生產前改換材料所花費的代價要高。在設計階段做好材料選擇工作,可以避免多數這樣的情況。在生產制造開始后出現了可供使用的新材料是更換材料的最常見的原因。當然,這些新材料可能降低成本、改進產品的性能。但是,必須對新材料進行認真的評價,以確保其所有性能都滿足要求。應當記住,新材料的性能和可靠性很少像現有材料那樣為人們所了解。大部分的產品失效和產品責任事故案件是由于在選用新材料作為替代材料之前,沒有真正了解它們的長期使用性能而引起的。
產品的責任訴訟迫使設計人員和公司在選擇材料時,采用最好的程序。在材料過程中,五個最常見的問題為:(a)不了解或者不會使用關于材料應用方面的最新最好的信息資料;(b)未能預見和考慮擦黑年品可能的合理用途(如有可能,設計人員還應進一步預測和考慮由于產品使用方法不當造成的后果。在近年來的許多產品責任訴訟案件中,由于錯誤地使用產品而受到傷害的原告控告生產廠家,并且贏得判決);(c)所使用的材料的數據不全或是有些數據不確定,尤其是當其長期性能數據是如此的時候;(d)質量控制方法不適當和未經驗證;(e)由一些完全不稱職的人員選擇材料。
通過對上述五個問題的分析,可以得出這些問題是沒有充分理由存在的結論。對這些問題的研究分析可以為避免這些問題的出現指明方向。盡管采用最好的材料選擇方法也不能避免發(fā)生產品責任訴訟,設計人員和工業(yè)界按照適當的程序進行材料選擇,可以大大減少訴訟的數量。
從以上的討論可以看出,選擇材料的人們應該對材料的性質,特點和加工方法有一個全面而基本的了解。
參考文獻 :
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3.林好轉.平行線分割一步平移法排樣算法的研究。鍛壓技術,1994,(5):33~35
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5. 華剛,肖祥芷,肖景容。沖裁件排樣的優(yōu)化設計。華中工學院學報,1987,6. H.S.Ismail,K.K.B.Hon. New approaches for the nesting of two-dimensional shapes for press tool design. International journal of production research,1992,30(4):825~837
7.周雄輝,彭穎紅. 現代模具設計制造理論與技術. 上海:上海交通大學出版社,2000
8.趙震. 實用型沖壓毛坯優(yōu)化排樣系統(tǒng)的研究與開發(fā),機械科學與技術,2002,21(2):312~314
9.金曉淮. 沖壓毛坯優(yōu)化排樣CAD系統(tǒng)的研制 上海交通大學碩士論文,1998
Process Planning and Machine design
The product design is the plan for the product and its components and subassemblies.To convert the product design into a physical entity ,a manufacturing plan is needed .The activity of developing such a plan is called process planning .It is the link between product design and manufacturing .Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product .In the present chapter ,we examine processing planning and several related topics.
At the outset ,we should distinguish between process planning and production planning ,which is covered in the following chapter. Process planning is concerned with the engineering and technological issues of how to make the products and its parts. What types of equipment and tooling are required to fabricate the parts and assemble the product ? Process planning is concerned with the logistics of making the product .After process planning is concerned with ordering the materials and obtaining the resources required to make the product in sufficient quantities to satisfy demand for it.
Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation.The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant .Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design.This is a point we will return to later.
Process planning is usually accomplished by manufacturing engineers .(Other titles include in industrial engineer.) The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings .Based on the planner’s knowledge,skill,and experience ,the processing steps are developed in the most logical sequence to make each part .Following is a list of the many decisions and details usually include within the scope of process planning :
Interpretation of design drawings The part of product design must be analyzed (materials,dimensions,tolerances ,surface finished,etc.) at the start of the process planning procedure.
Process and sequence The process planner must select which processes are required and their sequence.A brief description of processing steps must be prepared.
Equipment selection In general , process planners must develop plans that utilize existing equipment in the plant .Otherwise ,the component must be purchased ,or an investment must be made in new equipment .
Tools,dies,molds,fixtures,and gages The process must decide what tooling is required for each processing step.The actual design and fabrication of these tools is usually delegated to a tool design department and tool room ,or an outside vendor specializing in that type of tool is contacted.
Methods analysis. Workplace layout ,small tools ,hoists for lifting heavy parts ,even in some cases hand and body motions must be specified for manual operations .The industrial engineering department is usually responsible for this area.
Work standards Work measurement techniques are used to set time standards for each operation .
Cutting tools and cutting conditions These must be specified for machining operations ,often with reference to standard handbook recommendations.
For individual parts,the processing sequence is documented on a form called a route sheet .(Not all companies use the name route sheet ;another name is “operation sheet .”)Just as engineering drawings are used to specify the product design ,route sheets are used to specify the process plan .They are counterparts,one for product design ,the other for manufacturing .
The machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question.
Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge.
If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of product
Must regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.
A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.
Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method.
In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.
How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel's basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process.
Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method.
Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, worker's health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customer's aspect the and so on feedback pressure, can urge the people to carry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profound influence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order to can and guarantees the quality in the reasonable cost under the premise to obtain satisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material.
Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether has a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.
In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prototype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototype does not have the great value. Project engineer is best can completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the production design stage material replacement by other people, these people are inferior to project engineer to the product all functions understanding.
In the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantity can quite be easy to guarantee the supply.
In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certainly, these new materials possibly reduce the cost, the improvement product performance. But, must carry on the earnest appraisal to the new material, guarantees its all performance all to answer the purpose. Must remember that, the new material performance and the reliable very few pictures materials on hand such understood for the people. The majority of products expiration and the product accident caused by negligence case is because in selects the new material to take in front of substitution material, not truly understood their long-term operational performance causes.
The product responsibility lawsuit forces designs the personnel and the company when the choice material, uses the best procedure. In the material process, five most common questions are: (a) did not understand or cannot use about the material application aspect most newly the best information paper; (b) has not been able to foresee and to consider the dusk year possible reasonable use (for example to have the possibility, designs the personnel also to be supposed further to forecast and the consideration because product application method not when creates consequence.
In recent years many products responsibilities lawsuit case, because wrongly uses the plaintiff which the product receives the injury to accuse produces the factory, and wins the decision); (c) uses the material data not entire perhaps some data are indefinite, works as its long-term performance data is the like this time in particular; (d) the quality control method is not suitable