Computer aided design of prismatic turning tool
1. Introduction
The forming turning tool is a specialized cutting tool used for machining the surfaces of rotating parts. Its cutting edge is designed to match the shape of the surface being machined. Using such a tool ensures stable machining quality, high productivity, multiple resharpening opportunities, and a longer service life. However, traditional manual design methods are time-consuming, labor-intensive, and often lack precision. To address these issues, we have developed a computer-aided design (CAD) system for prismatic turning tools, aiming to reduce the design cycle and improve accuracy.
2. System Configuration and Operating Environment
Figure 1
The prismatic turning tool CAD system is built on AutoCAD R2000 as the platform, with Object ARX 3.0 used for secondary development through Visual C++ 6.0. The application is compiled into an ARX dynamic link library and runs within the AutoCAD environment. The user interface is in Chinese, with clear prompts at each step. The system follows a modular structure, including modules like initialization, tool structure design, profile design, graphic generation, dimensioning, and output (as shown in Figure 1).
3. CAD Design Method for Prismatic Turning Tool
The front and back angles of the forming tool are determined based on the workpiece material. Once the material is selected, the system automatically calculates the rake angle (gf) and relief angle (af). This helps ensure proper cutting performance and tool longevity.
1. Tool Structure Design
The clamping part of the prismatic turning tool uses a dovetail structure, which is robust and capable of withstanding large cutting forces. Key structural parameters include the total body width (Lc), body height (H), body thickness (B), and the size of the dovetail structure.
a. Total Body Width (Lc): The total width of the tool corresponds to the cutting edge width, calculated as Lc = l + a + b + c + d. Each parameter represents specific dimensions related to the workpiece profile, additional cutting edges, chamfers, and overcut prevention. These values are entered by the user through the command line in AutoCAD.
b. Body Height (H): The height should be maximized within the allowable range to increase the number of re-grinding cycles. Recommended values are H = 75–100 mm with a tolerance of ±2 mm.
c. Body Thickness (B): The thickness must ensure sufficient strength while considering chip removal and installation. It is also influenced by the dovetail structure and the maximum profile depth of the workpiece. The system automatically selects B based on the total width.
d. Dovetail Structure Size: The size of the dovetail is standardized and stored in a data file. The system automatically selects it based on the total tool width, ensuring compatibility with the clamping mechanism.
2. Tool Profile Design
Rotary parts typically consist of arcs, straight lines, and other curves. Before performing profile correction, the system distinguishes between arc segments and straight segments. It processes input data from the user, including diameters, tolerances, and axial distances, and generates coordinate points accordingly.
When the workpiece has a circular arc, the tool’s profile is not a perfect arc due to the rake and relief angles. However, for simplicity, an approximate arc can be used, with an increased radius. This approach is illustrated in Figure 3, where the actual tool profile is approximated using calculated coordinates.
3. Graph Generation and Dimensioning
a. Graph Generation: Based on the design data, the system defines point coordinates and determines the drawing direction. It then uses AutoCAD commands to generate working and template drawings of the turning tool.
b. Dimensioning: Dimensions are categorized into shape and position sizes. The system avoids repeated or missing dimensions and ensures clarity. It automatically labels all necessary measurements and saves the drawings as blocks for future use.
Image 3
4. Graph Output
a. Frame Settings: The system automatically selects the frame size based on the tool’s dimensions or allows user selection. It inserts the drawing block into the appropriate location according to a set scale.
b. Title Bar and Technical Requirements: Using Dialog Control Language (DCL), the system creates a dialog box for entering details like designer name, material, and scale. It then fills in the title bar automatically, as shown in Figure 4.
Figure 4
5. Conclusion
The prismatic turning tool CAD system was developed using Visual C++ 6.0 for AutoCAD R2000. Users simply enter the required design data, and the system generates a tool that meets specifications and outputs engineering drawings compliant with national standards. This system significantly improves design accuracy and efficiency, shortens the design cycle, and reduces costs. Additionally, the output can be easily converted into CNC instructions, making it highly practical and suitable for widespread adoption.
Wuxi Zijing Purification Engineering Co., Ltd , https://www.zijingjh.com