Research on Gate Valve CAD/CAM System

It is proposed that the gate valve CAD/CAM system should have functions such as optimization design, finite element analysis, parameter design, automatic drawing and computer-aided manufacturing, etc. The gate valve CAD/CAM system is thus developed and designed. The system uses design calculations, analysis, dynamic gallery, CAM and other modules to meet the functional requirements, and uses dynamic databases with real-time data exchange capabilities to tie together the various modules. In the design calculation, the design of each part adopts the parameter-driven conceptual model, which is driven by serialized size parameters to generate a specific model. In the numerical control programming, according to the characteristics of the parts, the system provides three rough cutting methods. The validity and effectiveness of the NC program can be verified through three simulation forms. The application of CAD technology in all walks of life has completely changed the traditional design model, creating enormous social and economic benefits. At present, CAD technology has moved from a simple drawing tool to an integrated CAD/CAM stage to support the entire process of product design and manufacturing. According to statistics, after designing and applying CAD technology, the factory product design shortens the design cycle by 1/3 to 2/3, improves the work efficiency by 3 to 10 times, and improves the success rate of product design at one time. The company has made great progress in manufacturing technology to modernize. Manufacturing has taken a big step [1, 2]. However, the vast majority of manufacturers producing gate valves in the oil industry and even in the country have long adopted semi-empirical, semi-theoretical traditional design methods. Product performance and delivery time cannot meet user requirements and affect the market competitiveness of products.

<br> <br> valve function design CAD / CAM system should be market-oriented, to meet customer needs, while using the existing achievements, the use of CAD / CAM design and manufacturing systems to achieve the integration of information flows, provide the basis for the management of information flow, as CIMS lays the foundation for small and medium enterprises. Therefore, according to the future development trend [3], the designed gate valve CAD/CAM system is a network-based open system and should have the following three major functions.

1. Optimization design and finite element analysis The design of the function gate valve is a modular design based on a series of model levels. The content of the design calculation is complex, requires high precision, and has a wide range of applications. Therefore, on the one hand, it has adopted advanced technologies at home and abroad in recent years. The scientific research results and new design calculation theory improve the overall performance of the gate valve, realize the replacement of gate valve products and meet the requirements of users; on the other hand, modern design methods such as optimization design and finite element analysis are used to establish an optimized processing capacity and structure. An efficient and practical design calculation module for analysis.

2. Parameter design and automatic drawing function Due to the change of the connection form and the different pressure levels, the structure of the gate valve is also various. The user's design parameters and requirements are different, and the structure changes at any time. In order to ensure the advanced and practicality of the CAD system, the module adopts a parameterized configuration [4], which mainly includes the following contents:

(1) Structural design of CAD system In order to improve the advanced nature of the product and rationally allocate and utilize computer resources, the gate valve is divided into two methods: "variable" and "invariable". The so-called "variable" refers to the part that changes with the design scheme, such as non-standard parts such as gates and valve seats. This part of the design and parameter drawing automatically completed, the computer automatically processed to determine the structure shape, size and size. The "invariant" part refers to the corresponding standard graphics library to meet the needs of various design solutions.

(2) Parametric Drawing Subsystem The CAD system can automatically determine the position of the parts in the assembly drawing, the assembly relationship and the automatic size inspection in addition to automatically completing the required graphics. Finally, the entire design drawing is output by the plotter. . In this subsystem, the dynamic library is the core. It includes more than 20 kinds of parts galleries with different specifications, such as series gates, valve seats, and handles, to ensure that the final assembly and design of parts and components and the drawing of the valve parts are completed at any time.

3.CAM function The CAM module automatically generates CAM required structure data and process information while performing detailed part structure and production of part production drawings, and automatically generates NC processing codes, working hours quotas, production plans, resource requirements, etc. NC simulation code simulation and development, in order to facilitate the actual tooling process and knife path simulation before processing, to avoid various damage during the process, to achieve CAD / CAM information integration.

<br> <br> system architecture to meet the above three functions, the author of gate valve CAD / CAM system is divided into five modules.

1. The design and calculation module refers to the world's latest theories and advanced scientific research results, and hangs an optimized design platform with more than 20 kinds of algorithms, which can shorten the original 20-day design period to 30 minutes or so.

2. The analysis module adopts MARC's advanced MARC non-linear finite element structural analysis theory and method to establish an advanced structural analysis module with pre- and post-processing functions.

3. The dynamic library module further perfects the "threeizations" of products, develops and develops products with an intelligent level on the basis of "threeizations", and forms a dynamic gallery of gate valves based on parametric design and parameter drawing.

4. The CAM module uses NC code technology and numerical control simulation technology to study the post-processing program of the CNC machine tool and the automatic generation of the NC code of the main parts. The simulation of the NC code ensures the processing quality.

5. The dynamic database integrates each module to realize the real-time transmission and invocation of information between each module, and together with each module constitutes a CAD/CAM system.

According to the manufacturer's specific product structure and requirements, the gate valve CAD/CAM system structure is shown in Figure 1. The design and calculation module solves the optimization design and calculation of various parts of the gate valve of different specifications. The library module is divided into a standard part library containing national standard parts and factory standard parts and a non-standard part graphic library that reflects the characteristics of the gate valve. The database module stores all kinds of design standards, responsible for the management of design data and graphic data, and real-time dynamic data exchange [5].

Fig. 1 Gate valve CAD/CAM system structure

The workflow and process information for the gate valve CAD/CAM system are linked as follows:

(1) Using the optimization design module and the finite element analysis module to conduct the design calculation and structural analysis of the overall valve gate optimization program, the structure and performance parameters of the gate valve are obtained, and the design parameters are stored in the database.

(2) According to the structural parameters of the valve design scheme, the system automatically performs the parametric structural design of the gate valve and its parts, and automatically draws and completes the drawing of the valve parts and components. In this process, the system automatically stores the structural parameters of each part. database.

(3) Complete pre-assembly of the gate valve and check for correctness.

(4) Automatically complete the structural refinement of various parts of the gate valve, automatically generate various types of parts production and processing drawings, and provide CAM with the structure and process information of each component.

(5) According to the process instruction, the CAM module takes out the structural process information of each component from the database, automatically generates the NC processing code of the component, and transmits the NC code to the CNC machining center to complete the processing of the component. If necessary, the machining code of important parts can be simulated to check its correctness.

Parametric Design of Gate Valve Parts
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br> Gate Valves There are 8 series such as 210, 400 MPa and so on. Each series is divided into different models according to transmission mode, connection mode, and structure type. Each model is divided into different specifications according to the size of the caliber. Each type of valve has more than 100 sets of drawings. Although the same type of gate valve has different series of products, the same series of products are divided into different types, but the structure of each type is basically the same, but the specific size is different. Specific types of gate valves, standard parts account for a large proportion, with 355.6mm (14 inches) Z40H-150 wedge gate valve as an example: 10 national standard parts, 11 standard parts, a total of 21 standard parts, accounting for the total parts About 75% of the number, so the design method of parametric modeling can well complete the design and drawing of gate valve products.

In the AutoCAD R14 environment, with its secondary development language, a parameterized design module that can be directly attached to the AutoCAD menu tree was developed. It uses a fully parametric design method of a part model that is independent of the AutoCAD interactive working environment. After the calculation of the constraint relationship is completed, the AutoCAD function is called to complete the design and drawing of the part. In the specific implementation, the user associates the size of the graphic with a certain design condition (or constraint), that is, the size of the graphic is regarded as a function of the design condition. When the design condition changes, the graphic size will be updated accordingly. When running, only a small number of major parameters (refer to determine the characteristic parameters of the valve part graphic, other dimensional relationships in the figure are indicated by this parameter), the computer automatically calculates the data of the dimensional relationship between the figures, and automatically designs and draws the figure. Fig. 2 is an example of a parametrically designed valve seat. In the figure, d0 is the main parameter, that is, the design parameter, r0 is the associated parameter, and other parameters can be calculated based on these two parameters. The designed seat table can use the base point and the control node. Technology is drawn.

Figure 2 Example of valve seat design

<br> <br> NC programming and simulation system, process and manufacturing information NC automatic programming according to the geometry of the part design, process design is provided, and machining simulation. For NC programming, the rough cutting form should be selected according to the characteristics of the part. The system provides three ways: rough cutting cycle, longitudinal rough cutting cycle and contour rough cutting cycle. The user can select a rough cutting cycle mode according to the actual shape of the part. The system then asks the user to enter the file name for storing the NC program. The system recommends that the extension use *.CNC.

When generating the NC program, the system will display the recommended rough machining depth and feed amount and the machining allowance of the finishing machining for the on-site operator's reference. If it is considered that the recommended value is not consistent with the actual situation on the site, you can Make changes and then automatically generate the part NC program that meets the requirements.

After the NC program is generated, machining simulation is required to verify the correctness and effectiveness of the NC program. This system checks the tool path by displaying the NC tool path on the blank, and realizes the static and dynamic simulation before machining. The system provides three simulation forms: static contour, static inspection (tool compensation trajectory), and real-time dynamics.

Static contour simulation requires the operator to input trace interval time and graphic scale to control the speed and size of the drawing. On the basis of the static contour simulation, if the cutter trajectory constituted by the cutter radius compensation and cutter length compensation is considered The static inspection of the trajectory; real-time dynamic simulation is a complete simulation of the actual machining process, and the actual trajectory of the center movement of the knife is dynamically displayed on the screen.

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