外文翻譯---減色添加劑固體自由成形制造過程規(guī)劃和自動化

1、<p><b>　　附錄A 英文原文</b></p><p>　　Process Planning and Automation for Additive-Subtractive Solid Freeform Fabrication</p><p>　　The demand in industry for fast, accurate renditions

2、 of designs is not new, and a whole community of specialized model makers and craftsmen has traditionally catered to this demand. This community has adopted new technology, like CNC machining, as it has become available.

3、 Nevertheless, the process of creating a model or a prototype of a design remained labor- and skill- intensive until the set of processes known collectively as Solid Free form Fabrication became feasible.</p><

4、p>　　The processes currently used in the SFF industry are purely additive, where material is progressively added to the part being built in the final position and shape. Newer processes coming out of the research labor

5、atories are using engineering materials (hard metals, ceramics), and are combining addition and subtraction of material as a way to shape more precisely the part. A comprehensive review of the available processes can be

6、found in [Prinz, Atwood et al. 1997].</p><p>　　Additive/Subtractive processes improve on purely additive ones in the range of materials they handle and the accuracy they provide. They are also proving to acc

7、ept more sophisticated design with multiple and graded materials in a single part [Weiss, Merz et al. 1997], as well as integrating whole assemblies in one single fabrication unit. The downside to all theseimprovements i

8、s that additive/subtractive processes require a substantially more sophisticated process planning and part execution con</p><p>　　The goal of this paper is to present a planning and execution framework for a

9、dditive/subtractive processes, outline the issues involved in developing such an environment, and report on the progress made in this direction at the Rapid Prototyping Laboratory at Stanford University. We take the SDM

10、process [Merz, Prinz et al. 1994] developed at Stanford as the case study to apply the concepts developed in planning and execution for this class of additive/subtractive SFF processes.</p><p>　　The first st

11、ep towards automated manufacturing is to establish efficient communication between design clients and manufacturing centers. A design client can be equipped with regular CAD packages or with specialized design software [

12、Binnard and Cutkosky 1998] where process- specific knowledge is embedded to facilitate down-stream planning tasks. On the other hand, manufacturing centers should provide manufacturability analyzers, automated process pl

13、anning software and on-line execution systems. T</p><p>　　Communication between designers and manufacturers can be accomplished by Internet-based process brokers [Tan, Pinilla et al. 1998]. These brokers rec

14、eive designs and check with available manufacturing centers for accessing turn-around time, material availability, facility capability, and dimensional accuracy. They then select manufacturers that best fit designers'

15、; requirements. Figure 1 shows a framework architecture that includes the concepts outlined here.</p><p>　　In the following sections, we will only address issues related to process planning and execution for

16、 additive/subtractive SFF processes.The first requirement for a realistic planning and execution system for any manufacturing system is to be able to interface existing CAD systems. The supplied solid models must support

17、 freeform surfaces for the sake of geometrical reasoning and path planning required for additive/subtractive processes and for the required levels of accuracy. Further development</p><p>　　The required func

18、tionality for a planning system can be summarized as follows:Planning for finding a building orientation [Hur and Lee 1998] has to account for the fact that additive/subtractive processes can deposit and shape full 3D sh

19、apes and is not limited to thin 2D layers part shape needs to be decomposed in volumes that are readily manufacturable with the process considered. Decomposition is substantially more complex to take full advantage of th

20、e non-planar capabilities planning each of </p><p>　　SDM and other additive/subtractive processes present a substantial increase in sophistication compared with pure additive ones regarding its execution env

21、ironment. The main issues that should be considered are:SDM is a multistage process: Multistage processes require or should allow multiple processing stations and transfer of parts between stations. An industrial SDM sho

22、p needs to determine scheduling of parts and operations, floor layout, assignment of jobs to machines, etc.As soon as multiple</p><p>　　These characteristics make the process somewhat similar to VLSI manufac

23、turing, where an array of processes work in sequence to produce a wafer. A wafer，route travels through a variable number of machines depending on its process plan, and it is very cyclic (Lithography-Etch-Implant). In a s

24、imilar fashion to VLSI manufacturing, the execution system will have to cover the handling of partially built parts and intermediate buffers.Process planning takes full 3D geometric models as inputs and output</p>

25、<p>　　Basic planning steps involve determining building directions, decomposing a part into manufacturable volumes (called single-step geometry), representing these sub-models in a structured format for allowing op

26、timizing building sequences, depositing materials on each single-step geometry, and shaping decomposed entities. The goals of these tasks are to generate process plans that are of low-cost, high-quality, high-precision,

27、and fast turn-around time. We will first define the constituent of the a</p><p>　　Additive/subtractive SFF processes involve iterative material deposition, shaping and other secondary operations. Each of suc

28、h operations is associated with a part component or a decomposed geometry, which together represent a final product. The characteristics of such decomposed geometry (a set of single-step geometries) are that all supports

29、 for its undercut features are previously built, and no interference should occur in depositing or shaping processes from the top with respect to the build</p><p>　　Operations associated with each single-ste

30、p geometry may include deposition with different types of material or machines, machining operations using CNC machines, or electrical discharge machining. Or it could be simple operations such as automatic insertion of

31、prefabricated components.The following describes issues related to automatic and optimal planning for additive/subtractive processes.The approaches are not dissimilar with other pure-additive SFF processes in determinin

32、g building directi</p><p>　　The number of decomposed single-step geometries reflects time for part building. In a typical additive/subtractive process, shaping operations usually need deposited materials to

33、be conditioned (in the case of plastics, cured/hardened; in the metal cases, cooled). The more the steps, the more the building time is consumed in the conditioning procedures.</p><p>　　To facilitate machini

34、ng tasks, it is preferred that a part has as many as possible flat or vertical surfaces with respect to the building direction. In the cases of free-form surface designs, an orientation that minimizes the number of under

35、cut-nonundercut transitions is most desirable since a surface without being split can be machined in one single operation which eliminates marks resulting from the layer interfaces.</p><p>　　An approach that

36、 maps surface normals to a unit sphere and determines the orientation that results in the minimum number of undercut-nonundercut transitions is described in [Rajagopalan, Pinilla et al. 1998].An algorithm that finds a fe

37、asible solution for this decomposition is described in [Ramaswami, Yamaguchi et al. 1997]. In short, once a building direction has been determined, this approach identifies all silhouette edges that denote transitions fr

38、om non-undercut surfaces to undercut feature</p><p>　　Parts may be decomposed to several smaller features or may result in sharp cavities that do not exist in the original design. These features increase dif

39、ficulty in machining and may require more expensive and time-consuming processes, e.g., electrical discharge machining (EDM) for metal parts.When a part is decomposed into several sub-volumes, their shared surfaces need

40、not be defined exactly unless they consist of different materials. This is due to the fact that the newly introduced surfaces r</p><p>　　The results of decomposition are structured in an adjacency graph wher

41、e nodes represent single-step geometries or other components to be embedded, and edges represent the adjacency relationship between connected nodes. After considering part building order, a directed graph that represents

42、 the precedence relationship among single¬step geometries can be constructed. From this precedence graph, one can identify in what order the single-step models should be built. </p><p>　　With the preced

43、ence graph, a set of alternative building plans can be generated. Each plan represents a possible building sequence on the decomposed geometry and can be chose optimally depending upon machine availability or other crite

44、ria such as minimum building time, or best possible surface finishing, etc. These building alternatives are passed to job shops for runtime job-shop scheduling. </p><p>　　Material is usually deposited in co

45、nsecutive 2D layers until a single-step geometry is completely built. The advantages of additive/subtractive processes are that deposition may not need to be net-shaped since material removal processes are involved. This

46、 helps reduce stress concentration and warpage problems and improve deposition path optimality that could reduce voids during deposition. An algorithm that describes a method of relaxing 2D-layer geometry based on its me

47、dial axis transform can b</p><p>　　In additive/subtractive SFF processes, there exist no tool accessibility problems if appropriate machine tools are selected. This is because any supports for undercut featu

48、res of a single-step geometry have been built in earlier stages and parts can be further decomposed according to machining constraints. Therefore, planning for machining operations need not consider interference problems

49、.</p><p>　　In additive/subtractive processes, automatic machining path generation is crucial due to the number of machining operations involved. These tasks include determining surfaces to be machined, selec

50、ting appropriate cutter sizes, retrieving corresponding cutting parameters from database, using the best cutting strategies for given surfaces, and generating tool paths for target machines.</p><p>　　We take

51、 the SDM process as a case study for the more general case of SFF additive/subtractive processes. SDM has two levels of operation at the shop level: executing each individual operation and building complete parts.SDM rel

52、ies on a limited set of primitive operations to build the parts. The execution system dedicated to machine operations must provide such primitives. These primitives are load/unload, mill/shape, deposit, cure, preheat, an

53、d cool. Other auxiliary operations may be needed that</p><p>　　Part building and process description language (PDL)Parts are built by a sequence of operations. Each part to be built is characterized by a pro

54、cess plan that is built in terms of the primitive operations presented above. Required operations are described allowing flexibility in the allocation of its execution to a particular machine as late as possible.</p&

55、gt;<p>　　No specific machine characteristics are built into the part plan description.The process plan determines sequencesof operations to build the part only to the extent necessary for correct completion of th

56、e part. The plan should leave as much flexibility as possible to the execution system for possible build-time optimizations. As an example of this, in figure 2 single step geometries 3 and 7 do not require any special or

57、dering between them to build a correct part. The process plan should reflect</p><p>　　For an industrial setting, SDM shops will be composed of differentiated machines to perform each operation. For each part

58、 and for each operation, it needs to be decided which machine to use. A first step is to match the operation requirements to the machine capabilities. In the system being built at Stanford, machine capabilities are descr

59、ibed parametrically by</p><p>　　Type of operation they support from the list of operations needed by SDM.Some general characteristics like maximum part size or weight.Operation specific parameters: materials

60、 available for deposition, tools available in a CNC mill tool magazine, achievable accuracy, 3 or 5 axis, etc.With this information, the pool of machines available for a particular operation is identified. The selection

61、of which machine to use within this pool will be determined by the cost and speed of the machine and by t</p><p>　　Shop scheduling activities and the manufacturing operation implementation at the machine lev

62、el are implemented in a shop information system with on line access to the status and control of the machines, and can be accessed on-line to submit parts for construction.SFF shop operation is likely to work with lot si

63、zes of one or very few parts. The execution system has to support a very high part mix, where each part has its own process plan. The shop control systemKeeps track of the state of constru</p><p>　　Can compu

64、te an estimate of cost and processing time. This will be used to determine which machine, among the available ones, is the best fit to perform an operation.Current research in manufacturing executions systems [Motavalli

65、1995; Gowan 1996] point to information system architectures using a distributed computing system [Whiteside, Pancerella et al. ; No-author 1997]. This type of system supports a multiplicity of agents that collaborate to

66、control production [Maturana and Norrie 1995; Ramos</p><p>　　Bidding among a set of competing agents has already been explored as a way for scheduling and assigning production resources to jobs or making des

67、ign resources in [Baker 1996; Tilley 1996; Parunak 1997]. This framework is adaptable to SDM given the parametrization of building operations and machine capabilities outlined above.</p><p>　　Currently at St

68、anford’s RPL, a first prototype of such system is being built using a CNC mill as the basis for an integrated SDM machine tool. The overall shop control will be tested on a simulated set of such machines. A web-based int

69、erface is being built on top of the execution software to provide access to the fabrication of parts from other sites than the RPL at Stanford and to provide a design/manufacturing interface.</p><p>　　The cu

70、rrent process planner being developed at Stanford Rapid Prototyping Laboratory is based on the Uni graphics system and its API’s. Models are imported in STEP format and are decomposed into single-step models. These sub-m

71、odels are structured in the adjacency graph, precedence graph and building alternative tree, which are implemented in C++.Deposition and machining codes are generated automatically within UG/Open API and UG/Open GRIP pro

72、gramming environment.The current execution system is i</p><p>　　The CAD model is decomposed into five single-step geometries. These geometries hold precedence relationships that are represented in a preceden

73、ce graph. This graph completely represents their building constraints. Deposition and machining code is then generated for each single-step geometry. This process code is used to directly drive machine tools.The overall

74、part plan is codified in the Process Description Language that encodes all possible building sequences derived from the building tree and</p><p><b>　　附錄B 漢語翻譯</b></p><p>　　減色添加劑固體自由

75、成形制造過程規(guī)劃和自動化</p><p>　　DEMA第二產(chǎn)業(yè)快速，準(zhǔn)確樣式的設(shè)計(jì)，是不是新的，整個(gè)社區(qū)的專業(yè)模型制作和工匠的傳統(tǒng)迎合這種需求。 這個(gè)社區(qū)已經(jīng)采用了新的技術(shù)，如數(shù)控加工，因?yàn)樗呀?jīng)成為可用。然而，創(chuàng)建一個(gè)模型或原型設(shè)計(jì)的過程中維持勞動和技能密集型的過程，直到組統(tǒng)稱為固體自由形式加工成為可行。</p><p>　　SFF行業(yè)中目前使用的過程是純粹的添加劑，其中逐步添加材料的一

76、部分被內(nèi)置在最后的位置和形狀。 較新的處理走出研究實(shí)驗(yàn)室正在使用的工程材料（硬質(zhì)金屬，陶瓷等），并結(jié)合加法和減法的材料，作為一種更精確的方式來塑造的部分。 [普林茨，阿特伍德等人可用的進(jìn)程，可以發(fā)現(xiàn)一個(gè)全面的檢討。 1997]。</p><p>　　添加劑/減色過程純粹在它們處理的材料，它們所提供的準(zhǔn)確度的范圍內(nèi)的添加劑的改善。 他們還證明，接受更先進(jìn)的設(shè)計(jì)，在一個(gè)單一的部分[魏斯，梅爾茨等多個(gè)梯度材料。1997

77、]，以及整個(gè)組件集成在一個(gè)單一的制造單元。所有這些缺點(diǎn)改進(jìn)是添加劑/消減過程需要一個(gè)更復(fù)雜的過程規(guī)劃和部分執(zhí)行控制。 這種增加的難度是使用數(shù)控機(jī)加工或類似的材料去除過程，需要協(xié)調(diào)一些不同的單元過程的結(jié)果。</p><p>　　本文的目標(biāo)是添加劑/消減過程中提出了規(guī)劃和執(zhí)行框架，勾勒出在開發(fā)這樣的環(huán)境中所涉及的問題，這個(gè)方向快速原型在斯坦福大學(xué)實(shí)驗(yàn)室所取得的進(jìn)展的報(bào)告。 我們采取的SDM過程[梅爾茨，普林茨等。 1

78、994]在斯坦福大學(xué)開發(fā)的個(gè)案研究，應(yīng)用開發(fā)的概念規(guī)劃及執(zhí)行這一類的添加劑/消減SFF過程。</p><p>　　自動化生產(chǎn)的第一步是設(shè)計(jì)客戶和制造中心之間建立有效的溝通。設(shè)計(jì)，客戶機(jī)可以配備常規(guī)的CAD軟件包，或與專業(yè)設(shè)計(jì)軟件[Binnard和Cutkosky 1998]過程中特定的知識嵌入到下游規(guī)劃任務(wù)。 另一方面，制造中心應(yīng)提供可制造性分析儀，自動上線工藝規(guī)劃軟件和執(zhí)行系統(tǒng)。 例如，可制造性分析儀，檢查公差

79、要求設(shè)計(jì)和驗(yàn)證他們的設(shè)備和加工能力。 過程策劃生成過程計(jì)劃和相關(guān)業(yè)務(wù)建設(shè)部分和機(jī)器代碼序列。 執(zhí)行系統(tǒng)讀取幾個(gè)備用進(jìn)程計(jì)劃（可能為許多不同的部分），并確定后續(xù)的操作和機(jī)器的基礎(chǔ)上上線的車間作業(yè)配置。</p><p>　　設(shè)計(jì)師和制造商之間的通信可以通過基于互聯(lián)網(wǎng)的過程經(jīng)紀(jì)人[譚皮尼利亞等。 1998]。 這些中間商收到設(shè)計(jì)和訪問的周轉(zhuǎn)時(shí)間，材料供應(yīng)，設(shè)備能力，和尺寸精度檢查與現(xiàn)有的制造中心。 然后，他們選擇最合適

80、的設(shè)計(jì)師的要求制造商。 圖1示出了一個(gè)框架體系結(jié)構(gòu)，包括這里闡述的概念。</p><p>　　在下面的章節(jié)中，我們將只解決相關(guān)問題的處理添加劑的規(guī)劃和執(zhí)行/消減SFF過程的任何制造系統(tǒng)的一個(gè)現(xiàn)實(shí)的計(jì)劃和執(zhí)行系統(tǒng)的第一個(gè)要求是能夠連接現(xiàn)有的CAD系統(tǒng)。 所提供的實(shí)體模型必須支持自由曲面的緣故添加劑/消減過程和所需的精度水平所需的幾何推理和路徑規(guī)劃。 CAD系統(tǒng)的進(jìn)一步發(fā)展能夠代表多材料部件和梯度材料部件是一個(gè)活躍的

81、研究領(lǐng)域，將有重大影響這些流程[Kumar和1997年杜塔。 八月]。</p><p>　　規(guī)劃系統(tǒng)所需的功能可以被總結(jié)如下：規(guī)劃查找一棟取向[許和李1998]必須考慮到一個(gè)事實(shí)，即添加劑/減法過程可以存入和形狀完整的三維形狀，并不僅限于薄2D 層部分形狀需要進(jìn)行分解，易于制造的過程中考慮的卷。 分解基本上是更復(fù)雜的，以充分利用的非平面能力規(guī)劃，每一個(gè)在兩個(gè)階段的過程中的分解的卷：規(guī)劃的沉積材料[花王1998]，

82、[Farouki Koenig等人。 1995]，為每個(gè)表面的最終形狀的加工。 添加劑/消減SFF，幾何簡化由于分解避免大多數(shù)的刀具干涉和工具訪問路徑規(guī)劃的特點(diǎn)的問題，提供一個(gè)更好的機(jī)會來實(shí)現(xiàn)自動化。</p><p>　　SDM和其他添加劑/消減過程呈現(xiàn)出復(fù)雜性大幅增加，相比純添加劑的關(guān)于執(zhí)行環(huán)境。 應(yīng)考慮的主要問題是：SDM是一個(gè)多階段過程：多級工藝要求或允許多個(gè)處理站與站之間的部分轉(zhuǎn)讓。 工業(yè)SDM店需要確定

83、調(diào)度部分和操作，樓層布局，分配工作機(jī)器等。只要被認(rèn)為是多臺機(jī)器，制造等幾部分組成，將要采取的并行處理優(yōu)勢，在不同的站，以最大限度地提高設(shè)備利用率。 每個(gè)部分都可以建立以下幾種可供選擇的序列。 執(zhí)行系統(tǒng)應(yīng)該能夠利用這種靈活性，以優(yōu)化成本并打開左右的時(shí)間。執(zhí)行系統(tǒng)的機(jī)器和交接部位應(yīng)協(xié)調(diào)活動，并跟蹤和每臺機(jī)器的負(fù)載平衡的狀態(tài)在本店實(shí)現(xiàn)暢通。</p><p>　　這些特點(diǎn)使這一過程有點(diǎn)類似超大規(guī)模集成電路制造的進(jìn)程的數(shù)組

84、，其中的工作序列，以產(chǎn)生??一個(gè)晶圓。 晶圓，路線穿越可變數(shù)量的機(jī)器，取決于它的工藝方案，是非常循環(huán)（光刻蝕刻植入物）。以類似的方式，以VLSI制造執(zhí)行系統(tǒng)將有覆蓋處理部分生成的零件，中間緩沖區(qū)的過程規(guī)劃充分的三維幾何模型作為輸入和輸出的過程描述，用于指定內(nèi)容的操作序列是必需的生產(chǎn)輸入部分。 內(nèi)容包含機(jī)器可理解的駕駛指定機(jī)器的代碼執(zhí)行所需的操作哪里序列指定所有可能的操作是有效的訂單，制造輸入部分。</p><p>

85、;　　規(guī)劃的基本步驟涉及確定建筑方向的一部分分解成可制造體積（稱為單步的幾何形狀），這些子模型以結(jié)構(gòu)化格式，用于允許優(yōu)化建筑物序列，沉積在每個(gè)單步的幾何形狀的材料，和整形分解實(shí)體。 這些任務(wù)的目標(biāo)是生成過程的計(jì)劃，是低成本，高品質(zhì)，高精密，快速的周轉(zhuǎn)時(shí)間。 首先，我們將定義的加法/減法過程的組成部分：單步幾何。</p><p>　　添加劑/消減的SFF過程涉及迭代材料沉積，整形等二次操作。 每一個(gè)這樣的操作相關(guān)聯(lián)

86、的一部分成分或分解的幾何形狀，它們共同代表最終產(chǎn)品。 等分解的幾何形狀（一組單步的幾何形狀）的特性，以前生成的所有支持它的側(cè)凹特征，無干擾發(fā)生在建設(shè)方向相對于從頂部沉積或成形過程。 換句話說，任何沿生長方向的射線投應(yīng)不相交的一個(gè)單步的幾何形狀，多于一次。</p><p>　　與每個(gè)單步的幾何形狀相關(guān)聯(lián)的操作可以包括不同類型的材料或機(jī)器，使用數(shù)控機(jī)床，或放電加工的加工操作的沉積。 或者它可能是簡單的操作，比如自動插

87、入預(yù)制組件。下面介紹自動和最優(yōu)的規(guī)劃添加劑/消減過程方法的相關(guān)問題沒有什么不同與其他純添加劑的的SFF過程中確定的建設(shè)方向。 不過，也有一些更添加劑/消減過程中需要考慮的問題：</p><p>　　分解的單步幾何數(shù)反映了部分建設(shè)的時(shí)候了。 在一個(gè)典型的添加劑/減色法中，整形操作通常需要空調(diào)的沉積材料（塑料的情況下，固化/硬化，在金屬的情況下，冷卻）。 步驟，建設(shè)時(shí)間被消耗在調(diào)理程序。</p><

88、;p>　　為了便于加工任務(wù)的部分，優(yōu)選的是具有盡可能多的盡可能的平坦表面或垂直表面相對于建筑物方向。 在自由曲面的設(shè)計(jì)的情況下，數(shù)量減少到最小的的底切非倒勾轉(zhuǎn)換的取向是最可取的，因?yàn)椴槐环指?，可以在一個(gè)單一的操作，從而消除產(chǎn)生層接口的馬克加工表面。</p><p>　　一種方法，表面法線映射到單位球上，并確定在最小數(shù)目的底切非倒勾轉(zhuǎn)換的結(jié)果的方向，皮尼利亞等人描述的[拉賈戈帕蘭。 1998]。拉馬斯瓦米，山

89、口等人[中描述的一種加密算法，找到一個(gè)可行的解決方案，該分解的。 1997]。 總之，一次建設(shè)的方向已經(jīng)確定，這種方法確定的所有輪廓邊表示非倒勾表面轉(zhuǎn)換功能削弱或反之亦然。 這些輪廓邊緣連同現(xiàn)有的邊的集合形成一個(gè)循環(huán)，這是用來分裂的表面。 模型，然后分解和支撐結(jié)構(gòu)產(chǎn)生一些擠壓操作的幫助。 雖然這種方法分解給出了解決方案，實(shí)現(xiàn)了更好的解決方案，需要解決以下問題：</p><p>　　部件可能會被分解成幾個(gè)更小的特征

90、，或可能會導(dǎo)致尖銳的空腔中不存在的原始設(shè)計(jì)。 這些功能增加加工困難，并且可能需要更昂貴的和費(fèi)時(shí)的過程，例如，放電加工（EDM）中的金屬parts.When的一部分被分解成幾個(gè)子??體積，它們的共享表面不需要被精確地定義，除非它們由不同的材料組成。 這是由于這樣的事實(shí)：由于新引入的表面分解的部分的內(nèi)部，不需要進(jìn)行機(jī)械加工，，因?yàn)楹罄m(xù)操作將存入相同的類型的材料，這些表面相鄰。</p><p>　　分解的結(jié)果構(gòu)造鄰接圖

91、的節(jié)點(diǎn)代表單步幾何或其他組件可以嵌入，邊代表連接的節(jié)點(diǎn)之間的鄰接關(guān)系。 在考慮部分建設(shè)秩序，代表的優(yōu)先級之間的單一關(guān)系¬步的幾何形狀，可以構(gòu)造一個(gè)有向圖。 從這個(gè)優(yōu)先圖，人們可以找出什么樣的順序應(yīng)該建立單步模式。</p><p>　　它們的優(yōu)先級圖，可以生成一組不同的建筑計(jì)劃。 每個(gè)代表一個(gè)可能的建筑計(jì)劃分解幾何序列，并且可以選擇最佳取決于機(jī)器的可用性或其他標(biāo)準(zhǔn)，如最小建立時(shí)間，或盡可能最好的表面處理，

92、等這些建筑的替代品傳遞到就業(yè)商店運(yùn)行車間作業(yè)調(diào)度。</p><p>　　材料通常沉積在連續(xù)的二維層，直到完全建立一個(gè)單步的幾何形狀。 優(yōu)點(diǎn)添加劑/消減過程中的沉積可能并不需要是網(wǎng)狀的，因?yàn)椴牧系娜コ^程中所涉及。 這將有助于減少應(yīng)力集中和翹曲問題，提高沉積路徑最優(yōu)，可以減少在沉積過程中的空隙。 描述了一種放松的2D層的幾何形狀的基礎(chǔ)上其中軸變換算法，可以發(fā)現(xiàn)在[1998年花王]。 通過這種方法，原始2D層的幾何形

93、狀是“固定”，以減少尖銳的角落和狹窄的通道，并為平滑的路徑優(yōu)化的沉積。</p><p>　　在加/減法SFF過程中，不存在任何工具的無障礙設(shè)施的問題，如果選擇合適的機(jī)床。 這是因?yàn)?，已建成了一個(gè)單步的幾何形狀的凹特征的任何支持在早期階段和部分加工的限制，可以進(jìn)一步分解。 因此，規(guī)劃為加工操作不必考慮干擾問題。</p><p>　　在加/減法流程，自動生成加工路徑由于涉及的加工操作怒江 MB

94、ER 是至關(guān)重要的 。 這些任務(wù)包括：確定被加工表面，塞萊cting的適當(dāng)?shù)那懈畛叽?，從?shù)據(jù)庫中檢索相應(yīng)的切削參數(shù)，使用最好的給定表面切削策略，并生成刀具路徑為目標(biāo)機(jī)器。</p><p>　　我們采取的SDM過程作為一個(gè)案例研究更一般的情況SFF加/減法的過程。 SDM店有兩個(gè)級別的操作：執(zhí)行每個(gè)單獨(dú)的操作，并建立完整的parts.SDM依賴于有限的一組原始的操作建立的部分。 專用機(jī)械作業(yè)執(zhí)行系統(tǒng)必須提供這樣的原

95、語。 這些原語的加載/卸載，磨/形狀，存款，治愈，預(yù)熱和冷卻。 可能需要其他輔助業(yè)務(wù)作為主要操作之間的橋梁。 這些可能包括洗，噴砂，噴丸拍攝，或特殊操作，如嵌入組件，檢查，等等。</p><p>　　部分建設(shè)和流程描述語言（PDL）部件內(nèi)置一系列操作。 每一部分的特點(diǎn)是要建一個(gè)過程計(jì)劃是建立在上述基本操作。 所需的操作，允許靈活的分配執(zhí)行到特定的機(jī)器盡可能晚。</p><p>　　沒有特定

96、的機(jī)器的特點(diǎn)建成的部分計(jì)劃介紹;工藝方案確定的操作序列，建立必要的范圍內(nèi)正確完成的部分僅部分。 該計(jì)劃應(yīng)留執(zhí)行系統(tǒng)可能建立時(shí)間優(yōu)化的可能盡可能多的靈活性。 一個(gè)這樣的例子，在圖2中單步3和7的幾何形狀不要求任何特殊訂貨它們之間建立一個(gè)正確的部分。 過程計(jì)劃應(yīng)該反映這種靈活性，而不是過度限制它們之間施加人為的次序執(zhí)行系統(tǒng)。 已經(jīng)設(shè)計(jì)過程描述語言，以適應(yīng)這一要求。</p><p>　　對于工業(yè)環(huán)境中，將SDM商店由差

97、別化機(jī)執(zhí)行每個(gè)操作。 每個(gè)部件和每個(gè)操作，它需要來決定所使用的機(jī)器。 的第一個(gè)步驟是匹配的操作要求的機(jī)器能力。 在斯坦福大學(xué)正在構(gòu)建的系統(tǒng)，機(jī)器性能參數(shù)描述</p><p>　　操作類型，他們支持從列表中所需要的一般特性，如SDM.Some最大的一部分的大小或重量操作的具體參數(shù)：材料沉積，可用的工具在一個(gè)數(shù)控銑床刀庫，可實(shí)現(xiàn)精度，3年或5軸的操作，還可作卷揚(yáng)此信息，可對某特定操作機(jī)器的pool被識別。 機(jī)內(nèi)使用此