The traditional methods used in the production of engineering machinery tire treads, such as layer-laying and set-up techniques, often result in poor compaction and limited product diversity. Especially for large-sized tires, these methods require significant manual effort. In contrast, many foreign manufacturers use tread winding machines to wrap the treads efficiently. One well-known example is the ALPHA-R machine from Malangoni in Italy. However, domestic bias tire winding machines still face challenges, such as an inability to wrap around the sidewall, resulting in shape and quality gaps, as well as lower production efficiency.
This paper introduces the tread winding process and quality control of the BTXC-3 engineering machinery tire produced by Chemical Baichuan Automatic Control Co., Ltd. The tread winding process typically involves five main steps: extrusion, conveying, pressing, cooling, and winding. The process and control systems of domestic machines are quite similar, but they still lack the precision and flexibility found in advanced foreign models.
Winding quality is a critical factor in ensuring the final product meets specifications. If the tread mass is too low, the green tire may not fill the mold properly, leading to porosity or even hollow areas after vulcanization. On the other hand, if the mass is too high, it leads to unnecessary waste of time and materials. The BTXC-3 machine can maintain a tread mass error within 2% to 5%, controlled primarily through the upper machine and PLC system.
To adjust parameters, users open the Twister software on the BTXC-3 machine and navigate to "Process Parameter Management." A recipe selection window appears, allowing users to choose or create a new recipe. For security, a password prompt is required before any changes can be made. Once authenticated, the user can access the parameter setting interface.
In this interface, the winding shape can be customized. The shape is defined by the number of winding segments, height, and layers. The outer layer must encompass the inner layer’s limits, and the zero line of thickness corresponds to the carcass's outer diameter. The curve of the outermost layer and the green tire's diameter determine the total volume. When the rubber formulation is stable, the theoretical weight can be calculated based on density.
Users can adjust the curve by clicking on the blue area in the dialog box, entering thickness values, distances, and correction factors. They can add, modify, or delete nodes. Since the curve is symmetrical, only one side needs to be set. For multi-layer winding, the program automatically generates similar curves for subsequent layers. If adjustments are needed, users can manually fine-tune specific points. Compared to the ALPHA-R model, the BTXC-3 offers a more intuitive and user-friendly interface.
Once the shape is set, thickness compensation parameters can be adjusted for fine-tuning. These parameters directly affect the actual thickness, making it easier to correct deviations caused by environmental changes or mechanical wear over time. There is no need to reconfigure the entire process curve.
The PC software also estimates the compound quality based on the winding curve, blank size, and material density. This allows for accurate quality predictions, especially when formulations change.
Accurate measurement of the winding thickness is essential for maintaining quality and shape. The BTXC-3 uses a cylinder, slide ball bearing, and measuring mechanism to calculate thickness. As the tire expands during winding, the slider retreats, and the analog signal is sent to the computer via a high-speed counter. Real-time comparison between the required and measured thickness ensures that the machine adjusts speed accordingly, ensuring consistent quality.
Several key factors influence the accuracy of the winding process:
1. **Measuring Head Cylinder Pressure**: The pressure should not exceed 4.5 MPa to avoid over-compression and ensure accurate feedback.
2. **Measuring Head Offset**: Proper offset ensures timely measurement without interference from previously wound strips.
3. **Rubber Strips**: The edges of the strips must align correctly, and guide rolls should have a suitable taper to ensure even wrapping.
4. **Winding Drum Speed**: Too slow reduces efficiency, while too fast affects compaction and venting.
5. **Strip Properties**: Thickness, width, temperature, and flash all impact the final quality. Optimal strip width is typically 60–80 mm.
By controlling the winding speed, measuring head hysteresis, and real-time thickness monitoring, the BTXC-3 ensures consistent quality and shape. The strip's properties during winding also play a crucial role in the final outcome. Any imperfections in the strip, such as flash, can affect the overall quality of the green tire. Overall, the BTXC-3 offers improved performance, reliability, and ease of use compared to older systems.
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