This article explores how CAPP technology can be used to design assembly processes, thereby improving equipment efficiency, enhancing quality, reducing design costs, and ensuring the smooth development of the organization's information system.
In recent years, tobacco equipment manufacturers have increasingly adopted CAPP technology, using computers to coordinate various activities. Significant progress has been made in programming component manufacturing processes; however, the design aspects of computer-based equipment assembly have received less attention. If the focus of this technology's implementation is limited to component manufacturing, its significance within the current manufacturing system cannot be accurately reflected. Therefore, this article discusses the relevant aspects of assembly design.
1. Regarding the sequence of assembly activities
1.1 Principles of Formulation
When carrying out this design work, in order to ensure that the steps in the process can reasonably guide the activities, the following three points should be strictly followed when defining the procedures.
First, decompose the entire machine layer by layer according to the product structure and assembly requirements, making it into units that can be assembled independently. Second, clarify the configuration order of each component and part within the same layer. Third, clarify the configuration order of each part.
1.2 Confirmation Principles
First, when installing components in series, prioritize those that are easy to install. Second, when installing components in parallel, prioritize those requiring higher precision. Third, when assembling a dimensional ring composed of multiple dimensional chains, the assembly principles are: start with the basic dimensional chain, proceed from common to general; from bottom to top; from inside to outside; from difficult to easy; from heavy to light.
1.3 Principle of Economy
First, based on the assembly levels, activities should be carried out sequentially from low to high. Second, when conducting assembly activities, start with those that are more difficult, have stricter regulations, and are more time-consuming.
2. On CAPP in Design
An excellent solution relies on well-organized technical information as a guide. Generally speaking, in conjunction with the product's structure and design specifications, process documents can consist of assembly system diagrams, assembly process cards, etc.
2.1 About the system diagram
Generally speaking, such equipment involves very complex assembly processes, and the relationships between the various components of the system are not easily expressed in words. Therefore, the development of drawings can clearly show the assembler the interrelationships between the various components.
2.2 Regarding the compilation of process cards
Process cards are used to describe the relevant assembly steps, activity elements, and sequence. They illustrate the steps of the activity and related precautions. In addition, they work with process diagrams to explain content that cannot be expressed in words.
2.3 Compilation of Assembly Parts and Components Bill of Materials
This list is used to describe the types and total number of items required for the activity. It can guide the work in conjunction with the assembly process.
2.4 Implementation Scheme of CAPP Assembly
2.4.1 Feasibility Analysis of the Derivative Assembly CAPP Scheme
In accordance with relevant regulations, the following points must be carefully considered to implement this technology.
First, analyze the product's structure and performance characteristics. Second, based on technical specifications, clarify the relevant configuration requirements. Third, determine the assembly sequence. Fourth, obtain technical information and clarify all assembly procedures.
A significant challenge in designing using this technology is how to clearly define the sequence of elements in the design using a computer system and explain their interrelationships. While numerous drafting software programs exist, capable of converting complex drawings into electronic formats, computers have limited capabilities in automatically recognizing such drawings. To maximize the advantages of this technology, a derivative CAPP (Computer-Assisted Design Program) model can be developed. This model can significantly streamline the process, improve efficiency, and reduce the negative impacts of human error during the design phase. By comparing the component lists of tobacco machinery products such as the ZJ17 and ZJ112 high-speed cigarette making machines, the ZB47 and ZB45 hard-pack packaging machines, and the ZF12 and ZF12A tobacco storage and conveying systems, it becomes clear that while similar products may have significantly different performance characteristics, many of their components are very similar. Clearly, the systems composed of these similar components also share certain commonalities, making the aforementioned approach reasonable.
2.4.2 Technical Elements of Common Functional Modules
(1) Resource Management Module
The resource management module includes the management of the process database and the process document library. The tobacco machinery assembly CAPP database can be designed using a relational database management system (RDBMS) like SQL Server. SQL Server's greatest advantage is its use of a relational model to build a relational database. The data in the database is essentially a two-dimensional table with tuples or records as units. Columns in the table are attribute domains of one or more elements. This type of relational data table offers high data independence, with each attribute column having strict relationships and definitions, as well as standardized technical support. Records are stored in tuples, and record manipulation is also based on a single tuple, making it very flexible and efficient for subsequent queries.
Resource management of process documents can be carried out by process personnel with management authority through human-computer interaction, combining current production factors and steps to maintain previous or established plans, such as deleting or expanding the scope of use, and ensuring the rationality of the process.
(2) Assembly process design module
The automated design of the assembly process is a crucial core module of the system. It includes the input of assembly process information, the retrieval of process resources, the design of process documents, and the execution of the system program. When designing this module using VC++, a class is created for each typical assembly process and step in tobacco machinery assembly. This class contains all the input variables and function members that describe its characteristic information, thus establishing the basis for interactive process decision-making.
During the design process, process engineers, based on the derived CAPP design scheme, first input overall information through the human-computer interaction interface according to the system prompts. Then, the program automatically searches the process database and process file library according to the work sequence principle in assembly to check if there are similar example processes. If so, it directly calls and loads the process, and then derives it by editing and saving it. If not, the system automatically collects relevant information for process engineers to refer to, and the process engineers then carry out generative design.
2.5 Methods for Implementing Assembly CAPP
2.5.1 Standardization of assembly process
In the process of developing assembly processes, for some general-purpose mechanisms, assembly methods and requirements have already been standardized or specified by national and industry standards or manuals, which can be directly applied. For assembly methods without national or industry standards, the assembly content of similar components can be unified according to the principle of similarity, establishing enterprise standards. This allows for the creation of assembly process cards for similar structures, achieving generalization and standardization. For product-specific components, dedicated process cards are re-developed, creating both general standard assembly process cards and dedicated process cards. During assembly process design, frequent use and assembly of process cards can greatly simplify the design process. Encoding the assembly process cards according to the enterprise standard coding rules established by the company facilitates annotation activities on drawings. This ensures that assembly workers can not only clearly understand the composition system of all components and the specific assembly steps from the drawings, but also, combined with the coding, understand the process card information for all steps, thus ensuring that assembly activities can be carried out using the cards.
2.5.2 Utilizing CAD technology to assist in process design
Due to its remarkable achievements, this technology is widely used in the component manufacturing industry. The design and production of components require effective integration with modeling software to create 3D models.
When carrying out the design work, the proper use of the organization's drawing software can effectively test the feasibility of the design.
3. Conclusion
The complexity of such equipment makes its design process highly intricate. It encompasses the analysis of technical specifications, the selection of configuration measures, and related activity planning. It involves a wide range of areas, a vast amount of applicable information, and is closely linked to the actual activity environment and the capabilities of the workers. By analyzing current manufacturing industry regulations for this process, and taking future virtual units and networked production processes as a major premise, and the comprehensive use of CAPP as a guarantee, the design scheme can be successfully implemented. Through practical application, it not only improves design efficiency and reduces costs, but also, in tobacco machinery manufacturing, the comprehensive application of CAPP can serve as a foundation. Through its integration and resource sharing with CAD, PDM, and ERP, an integrated manufacturing process information system for process design and management can be established, becoming an important foundation for the informatization of manufacturing enterprises.
