山西十一选五复试 www.si6n.cn 基于PLM的航天器总装工艺系统的构建论文翻译
Construction of PLM-based Spacecraft General Assembly Process System
Abstract: Aimed at the challenges faced by spacecraft general assembly process management under 3D design condition, this paper analyzes the application demands for the construction of process system based on 3D model, puts forward the overall framework of spacecraft general assembly process system and gives the ideas and methods for key technical problems in system implementation.
随着信息技术的发展及其在制造业的深入应用，很多企业开始在产品设计中广泛地采用三维CAD技术，并通过推行MBD(Model Based Definition，基于模型的数字化定义)来提高企业的快速响应能力，也就是在三维模型中包含产品外形以及全部制造特征在内的信息，并在制造过程中完全以三维模型为设计、制造的唯一依据。
With the development of information technology and its further application in manufacturing industry, many enterprises begin to widely use 3D CAD technology in product design and to improve their quick response abilities by carrying out MBD (Model Based Definition)), namely, the information on product appearance and all the manufacturing characteristics is contained in 3D model which shall serve as the sole basis for design and manufacturing in the process of manufacturing.
国外企业的数字化设计制造技术起步较早，先后经历了以只使用二维工程图、二维为主三维为辅、三维为主简化二维图为辅以及全面推行独立三维模型定义的发展过程。波音公司在787项目中通过建立GCE((Global collaborative environment，全球协同环境)平台，基于网络建立了关联的单一数据源的核心流程和系统框架，实现了飞机研制的全生命周期的管理。
Digital design and manufacturing technology was started relatively earlier in foreign enterprises, it has successively experienced the following development history: only 2D engineering drawing was used, 2D was primary and 3D was secondary, 3D was primary and simplified 2D was secondary and independent 3D model definition is comprehensively carried out. Through establishing GCE (Global collaborative environment) platform, Boeing Company established the core process and system framework of associated single data source based on network in Project 787, thus realizing the full lifecycle management for development of aircrafts.
At present, domestic aerospace industry is developing rapidly in terms of application of MBD; many enterprises have established 3D digitalization design standards and established PLM platform to manage 3D design data. In terms of digitalized process design and digitalized manufacturing, however, its application practice is lagging relative to digitalized product design since it’s in the downstream industry chain, thus failing to form mature process design and manufacturing mode.
How to realize 3D-based process design under the condition of 3D design is of great significance for opening up 3D design and manufacturing channel, realize integration of design and manufacturing and promote enterprise competitiveness.
I. Business Requirement Analysis
1. Business status quo
Spacecraft general assembly involves the whole process from delivery of various subsystems of spacecraft for general assembly and acceptance to completion of all the assemblies and tests and to delivery for launch. Under the new situation of product design based on 3D model, the current general assembly process mode has seriously restricted the development of new models. It is mainly manifested in the following aspects:
(1) Lack of data management platform to manage 3D design model and product structure. Under the condition of digital design and manufacturing based on 3D model, the original paper design documents are replaced by digitalized 3D design models. First, this urges the manufacturing department to effectively manage the design data which serves as the input source of spacecraft general assembly after the technical state of design department is controlled. The design data includes 3D design model files, technical requirements of design, design BOM and other information.
(2) Lack of structured process design means based on 3D model. Assembly and Environmental Engineering Department still uses tabulated CAPP tool—Tianhe CAPP which was implemented in the early stage of informatization construction for process design. This kind of process design tool is relatively applicable when paper process document output is needed; however, today when digital manufacturing is popularized, it can’t satisfy new business requirements. In addition to not supporting 3D model, since its process data is unstructured data, it is not conducive to integration with MES system. Therefore, in the process of implementation of MES system in this unit, some rules were formulated to restrict the process design format and complex algorithm was adopted to systemize the process data, data sharing was realized consequently.
2. Demand analysis
For the above status quo and problems, a set of brand-new process realization framework based on 3D model needs to be established. Under the new framework, the integrated management of 3D model from design to manufacturing shall be strengthened, 3D process design shall be supported, technical state management shall be realized and the integration demands of application systems such as manufacturing execution system shall be met. The specific demands are as follows:
(1) To realize technical state management based on product structure. Based on product structure, take the spacecraft models as the principal line to realize technical state management of model design and to uniformly manage 3D models designed and all kinds of technical requirement documents of design. Based on this, manufacturing department should be able to carry out process planning according to the design data and establish process BOM, thus facilitating subsequent detailed design of process and directing on-site production.
(2) To realize structured process design based on 3D model. Most of the contents of spacecraft general assembly process are assembly process. With the development of large spacecrafts such as manned spacecraft, the systems are more and more complex and the requirements for operators of general assembly are higher and higher. In this case, it’s hard for 2D process to express complex space assembly structure and location. Therefore, full utilization of visualization advantage of 3D model can completely express the design and process intentions in process design and improve production quality.
(3) To realize the integration with other application systems. Since the product data management platform of design department is independent of that of manufacturing department; to realize the automatic receiving of design data, integration shall be realized with the related PLM system of design department. In addition, the results of process design shall be used for directing on-site production eventually, so it still needs to be closely integrated with Kanban system used for manufacturing execution process management of general assembly.
II. Overall Framework of System
Based on the demands for design data management and process data management of spacecraft general assembly process platform, the overall framework of system is hereby given, as shown in Figure 1.
The core function of the platform is based on mature PLM platform construction. Take Teamcenter as an example, it is a solution of Siemens Company to product lifecycle management provided for manufacturing; in addition to the basic function of product data management including document management, authority management, product structure and configuration management and workflow management, etc., it also provides a manufacturing process solution. Its core idea is to establish correlation among product, process, factory, manufacturing resources and other data, thus ensuring the consistency of data and realizing the reuse of data.
Based on this system framework, the business realization process is as follows:
● To obtain the design data including 3D model from design department manually or automatically through system integration. Import the data into process system via CAD integration interface of system.
● To reconstruct based on design data and supplement all kinds of process design input data to form process digital prototype.
● To carry out process planning and structured process design aimed at specific types of process digital prototypes. In the process of process design, assembly simulation can be conducted by using Delmia tool based on 3D model to verify the manufacturability. Similarly, based on 3D model designed, CAD tools like Pro/E can be used for carrying out process equipment design.
● For model scheduling, planning and scheduling shall be conducted in production planning system according to process design results. The operators and inspectors of general assembly check the process documents through Kanban execution system to conduct general assembly operation.
● The important data concerned by production schedule and design for general assembly of spacecraft needs to be extracted from production process data and returned to process system to form a practical digital prototype.
III. Key Technology
1. Design data receiving
Because general assembly department corresponds to multiple product design departments such as communication satellite and manned spaceflight, the product design of these departments includes not only 3D models based on pro/e but also 3D models based on Catia; these design models are managed by independent product data management system of each unit. General assembly department needs to receive these heterogeneous CAD models and use its own product data management system to manage them before carrying out process design and other work; as a result, a unified data receiving interface needs to be established.
When a design department needs to issue design data, it needs to create a distribution order object for associated design data in product data management system; after the distribution order is approved, it will automatically pack the design data and send it to intermediate server.
Design data package contains the information such as design BOM, component attributes, model attributes, model structures, relations between models and components, relations between components and documents, engineering change attributes, baseline content and validity attributes, etc. Structurally, data package is composed of a data specification description file and a folder containing all kinds of data such as 3D models, notices and change orders, etc. The data package exported by each design department from product data management system must generate such a unified file structure; only in this way, can general assembly process system be processed uniformly.
General assembly process system can poll intermediate server at fixed time or as required; if there is a new data package, it will automatically download data and import it to this system. The most critical link in data importing process is lightweight conversion of 3D model; since the 3D model imported may be Pro/E or Catia, Pro/E integration interface and Catia integration interface of PLM shall to be invoked respectively.
2. Construction of process digital prototype
In different development stages of spacecraft, its development processes are different. In particular, take initial prototype stage as an example, multiple structure stars, electric property stars and thermal control stars of different states will be assembled for carrying out mechanical test, electric performance test and thermal vacuum test. There are the same and different parts for the structures of these stars. For example, the structural parts of structure star are real parts; while instruments and equipment can serve as process parts; the structural parts of electric property star can serve as process parts, while instruments and equipment are real parts.
In order to manage these different states of spacecraft models, it is necessary for technologist in charge of models to establish BOM views of structure star, electric property star and thermal control star respectively based on product structures designed, thus forming process digital prototypes of multiple states.
3. Structured process design
Spacecraft general assembly process documents are productive guiding documents prepared according to the patterns and documents designed for general assembly of satellite and spaceship, etc. by combining the specific conditions of this unit; they’re not only used for directing the specific work of on-site assembly personnel, but also the important basis for inspectors to inspect the products. Therefore, the quality level of general assembly has a direct impact on ensuring the overall performance of spacecraft, functions and reliability as well as developing cycle.
The information model of spacecraft general assembly process document is shown in Fig. 2.
Spacecraft general assembly process of one model is composed of several process fascicules which include not only official process documents prepared in the process preparation stage but also temporary process documents prepared supplementarily according to production needs in the process of general assembly production. Each process fascicule is composed of working procedures and steps.
For spacecraft general assembly process, there is an important requirement; that is to record the installation condition of each set of equipment in detail; not only to confirm whether the equipment is installed accurately, but also to record the actual value of force measured. There are totally 111 kinds of states or parameters that need to be recorded, involving 14 categories of components including final assembly parts, structural deck, fasteners, thermistor and multilayer components, etc. A special category called execution record needs to be established in order to manage so much state or parameter information in the system, which shall be associated with operating steps, thus forming structured data so as to accurately record and query. Fig. 3 is process preparation interface; you can insert multiple execution record requirements for each operating step.
4. Use of 3D model
After 3D design model obtained from design department is imported to PLM system, the system will have original CAD model and lightweight JT model. Since paper drawings are not provided, these 3D models are main tools to express design intents. If technologists want to use 3D models to express process intents in process documents, they can apply 3D models through three modes:
(1) To capture screen of 3D model. In PLM, product’s 3D assembly state can be viewed according to product structure. In order to describe some specific assembly steps, technologist can capture screen and add remarks for 3D image in this state so that the operator can be clear about the operational details. Through secondary development of related menu or button, technologist can quickly complete this process in the course of process preparation.
(2) To use lightweight 3D model file. Specific operational steps can be described in the form of text-graphics mixture by using screenshot of 3D model; but for some complex assembling scenes, it’s relatively difficult to describe with static pictures. By using the visualization effect of lightweight 3D models such as JT and PVZ, operator can freely operate 3D assembly parts and view the assembling state from multiple angles so as to complete the assembly correctly.
(3) To use 3D simulation video. Lightweight 3D model can make us intuitively understand the final state of assembly, but it can’t demonstrate the whole operating process in the form of animation. Through importing 3D model in assembly simulation software like Tecnomatix, we can put the video file for simulating assembling process in the process document, thus making the operator operate according to the video.
5. Integration with MES
After the completion of structured process document preparation in PLM, it shall be finally used by operators and inspectors on production site. In terms of spacecraft general assembly business, Beijing Institute of Spacecraft Environment Engineering has implemented and applied MES system for many years; through developing Kanban system, it has realized issuance of production plan, division of team tasks, product supporting management and execution management of production site. Checking process documents in Kanban system according to structure, executing according to process documents and recording the relevant parameters in real time and submitting execution results have become the mature working mode of general assembly of spacecraft.
Fig. 4 is the integrated framework schematic diagram of process system with MES system. After process preparation is completed in process system, the formed structured process document shall be transferred in the form of xml file to MES system, the latter is responsible for parsing xml file and showing the process document to user in the form of webpage. User can view the operating content, JT model and simulation video via webpage to carry out assembly operation, and fill in the states or parameters required by process document in real time. Moreover, MES system also needs to deal with temporary scheduling instructions given in process system due to process change and to feed back the process problems found on production site and production execution state to process system.
Through analysis on spacecraft general assembly process under 3D design condition, this paper puts forward the overall framework of spacecraft general assembly process system based on PLM platform and expounds the key links such as design data receiving, construction of process digital prototype, structured 3D process preparation and integration with MES system. Seen from practical application effect, this solution has solved some bottleneck problems for “3D going to factories” and made the application of 3D model throughout the whole development process of spacecraft from design, process to manufacturing.上一篇： 食品公司直营店广告海报翻译，广告酬宾海报翻译