**Abstract:** This paper discusses the current status and user requirements for heavy-duty horizontal lathes and roll lathes, focusing on how to upgrade conventional models into advanced, aesthetically pleasing, and user-friendly CNC heavy-duty lathes. It compares the C61200 general model with new digital pull-type and numerically controlled retrofit versions, highlighting the benefits of modernization in terms of performance, efficiency, and usability.
**Keywords:** heavy-duty lathe; roll lathe; numerical control; design; transformation
**1 Introduction**
The modernization of traditional heavy-duty horizontal lathes and roll lathes through CNC retrofitting is a fast and effective way to meet the growing demands of manufacturing industries. These machines are essential for high-efficiency, heavy-duty cutting operations, including rough and finish machining of materials such as carbon steel, forged steel, alloy cast iron, high-speed steel, and Gao Ming steel. They can perform high-precision, low-roughness automatic cutting on outer circles, inner holes, end faces, tapers, internal and external threads, arcs, and complex curved holes.
Tangshan Heavy Duty Machine Tool Plant has successfully upgraded several standard heavy-duty horizontal lathes, such as the C61125A, C61160, and C61200G, for China's largest metallurgical roll manufacturer. The results have been highly beneficial from an economic standpoint, proving the effectiveness of CNC retrofitting.
**2 Comparison of Main Parameters and Performance Between Conventional and New CNC Heavy-Duty Lathes (Roll Lathes)**
(See Table 1)
Taking the C61200 general model and the new CNC heavy-duty horizontal lathe as examples, we can observe the following:
1. **Main Parameters and Drive Speed Range**: Both conventional and CNC models share similar main parameters and drive speed ranges.
2. **Feed Range and Control**: The conventional model has a limited feed range, using step-variable mechanisms that rely on multiple mechanical components. In contrast, the CNC model offers a wide, infinitely variable feed range, with independent transmission systems for each axis, controlled by AC servo motors. This increases rapid movement speed by two times, improving efficiency and reducing setup time.
3. **Machining Principle**: Conventional models require forming templates for complex hole shapes, resulting in lower accuracy and inefficiency. The CNC model uses program-controlled interpolation, enabling precise and efficient machining of any shape without physical templates.
From these comparisons, it’s clear that the main focus of CNC retrofitting lies in modernizing key components like the spindle, feed system, and tooling.
**3 Design Content of CNC Retrofitting**
The retrofitting process involves dismantling the original light bar and screw, re-grinding the guide rails, and installing high-precision helical racks. The main spindle and gear system are optimized, with encoders and advanced digital or AC variable frequency speed control systems added.
The vertical and horizontal feed systems are redesigned, replacing the original tool holder, carriage box, and feed box with CNC-compatible units. Key components include:
- **Numerically Controlled Tool Rest**: Features a carriage dragging plate, horizontal slide plate, and AC servo-driven ball screw for precise transverse movement.
- **Numerical Control Slide Box**: Designed for long-distance, high-precision feed movement, using anti-backlash structures and precision gratings for closed-loop control.
- **Frame-Type Tool Holder**: Provides high rigidity, radial positioning, and rapid tool change capabilities, allowing for internal hole and thread machining.
- **Tool Holder Walking Platform and Hanging Operation Button Station**: Enhances operator convenience and centralized control.
- **Renishaw Probe**: Enables accurate workpiece inspection.
- **CNC System Options**: Supports FAGOR, Siemens, and other systems, offering linear/circular interpolation, tool compensation, and simulation features.
**4 Comparison of Main Performance Parameters Between New NC and Retrofitted Heavy-Duty Lathes**
(See Table 2)
Comparing the C61200 new CNC model with the retrofitted version reveals that:
1. **Main Parameters**: Are largely the same.
2. **Drive Performance**: Similar, but the retrofitted model has a more complex internal structure, making maintenance slightly more challenging.
3. **Feed Motion Parameters**: Match closely, with consistent structural design.
4. **Bed Protection**: The new CNC model includes full-length protective covers for the bed’s longitudinal rails, while the old machine cannot be fully protected, leading to potential damage over time.
**5 Conclusion**
In summary, after CNC retrofitting, the performance and main parameters of heavy-duty horizontal lathes and roll lathes are comparable to those of new CNC models, except for bed protection. However, the cost is about one-third of new machines, and the production cycle is halved, making retrofitting a highly cost-effective and efficient solution.
Ruijiming (Shandong) Biotechnology Co., Ltd , https://www.mgpdrn.com