Rubber is a non-metallic material known for its unique mechanical properties, such as high elasticity and the ability to withstand significant deformation without damage. However, it has relatively low strength. The mechanical behavior of soft rubber and hard rubber differs significantly. Soft rubber exhibits about 1,000 times more flexibility than hard rubber. In practical manufacturing, cutting tools are commonly used to process rubber, but this often leads to issues like sickle-shaped chips, serrated edges, and rough surfaces on the finished parts. However, by leveraging the specific mechanical properties of rubber and using specially designed tools along with optimized cutting parameters, satisfactory results can be achieved.
**1. Process Analysis of Parts**
Figure 1 illustrates the machining of a component from an aerospace product manufactured by our company. The material used is HG1142 rubber, which has the following key characteristics:
- During processing, rubber exhibits excellent elasticity, leading to large deformations that make size control challenging.
- It has poor thermal conductivity and heat resistance. When the cutting temperature exceeds 60–150°C, the material can degrade, melt, or emit an odor.
- Rubber has low strength but high toughness, requiring cutting tools with extremely sharp edges.
- Industrial rubber often contains impurities, making the cutting edge prone to chipping or cracking.
**2. Tool Design**
Based on the analysis of the part's machinability shown in Figure 1, the geometric angles of the tool used for rubber differ significantly from those used for metal materials. Due to the special requirements of the rectangular thread on the rubber roller, the groove depth is considerable. The surface must be smooth, and a combined turning tool is used, as shown in Figure 2.
The main feature of the tool is that it consists of two cutters: a left cutter and a right cutter. The left cutter has only one straight edge, while the right cutter features a 90° edge. When combined, they form a "door" shape, allowing chips to be expelled from the center between the two cutters (as seen in Figure 3). The tool has a small wedge angle of 8° to 10°, ensuring a sharp cutting edge and light cutting force. The left cutter has an outer rake angle of 10° and an inner rake angle of 2°, and it must be tilted to the left, as shown in Figure 4.
The right cutter also has outer and inner rake angles of 10° and 2°, respectively, but it must be tilted to the right. The top edge has a back angle of 6°, and the inner side is inclined at 25°, as shown in Figure 5. Both cutters are welded tools made from YG8 carbide blades, with the tool body constructed from 45 steel.
**3. Tool Usage**
After assembling the left and right cutters, a gap of 0.03 to 0.05 mm is left between the blades to prevent collision. Since the material is rubber, the workpiece tends to elastic recovery after machining, causing the groove width to increase by 0.1 to 0.15 mm during sharpening. To reduce friction between the cutters’ outer surfaces and the thread, the tool should be installed slightly below the workpiece’s center. The reduction amount H is calculated as H = 0.707R (where R is the outer radius of the rubber roller). The feed depth t during machining should be greater than the thread profile depth h, with t = 1.414h.
To minimize cutting temperature, extend tool life, and improve surface finish, compressed air cooling is essential during the cutting process. Before machining, the end of the rubber roller is chamfered at 20°, allowing the cutter to gradually enter the workpiece from shallow to deep, ensuring stable guidance.
**4. Conclusion**
By analyzing the properties of rubber and considering its unique machining characteristics, we designed a suitable tool that meets all processing requirements. This approach ensures efficient and accurate machining of complex rubber components.
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