Abstract
To ensure the overall operational performance of railway locomotives and tracks, axle load control is a critical requirement. As part of this effort, the driven gears in HXD
2 series freight locomotives are equipped with eight φ 130mm weight-reduction holes to optimize weight distribution. To enhance the manufacturing process and reduce complexity, this paper explores the use of flame cutting combined with fine boring as an efficient method for creating these holes. It also discusses improvements in the quality and precision of the flame-cutting process.
1. Introduction
In response to the growing demand for improved passenger and freight transportation capacity in China's railways, China North Locomotive Group Datong Electric Locomotive has introduced and independently developed the HXD
2 series high-power, heavy-duty AC-driven freight electric locomotives. These locomotives feature a drive unit designed to strictly control axle weight, ensuring both the locomotive’s performance and track safety. The driven gear includes eight φ 130mm weight-reduction holes on its web, reducing the total weight by 60kg (from 500kg to 440kg). A schematic of the structure is shown in Figure 1.
To simplify the machining process and improve efficiency, this paper evaluates various methods for drilling the eight φ 130mm weight-reduction holes. Based on practical considerations, it proposes the optimal plan involving flame cutting followed by fine boring, along with necessary process improvements to ensure quality and consistency.
2. Comparison of Machining Methods for Weight-Reduction Holes
Given the high reliability and safety requirements of locomotive gears, the final surface of the weight-reduction hole must be cold-worked. This paper compares three machining techniques: machining center milling, CNC boring, and flame cutting combined with fine boring. Table 1 summarizes their processing efficiency, cost-effectiveness, and other relevant factors.
From the comparison, it is clear that the flame cutting + fine boring method offers the shortest processing time and best economic value, making it the preferred choice in actual production. Further details can be found in the attached document or in the 18th issue of Metalworking Magazine (Hot Processing).
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