Grinding Stone Performance Evaluation Method

Grinding Stone Performance Evaluation Method

The most crucial aspect of the grinding stone development process lies in evaluating and verifying its performance (including size and accuracy, dynamic/static balance, rotational strength, load-bearing capacity, grinding performance, etc.), thereby guiding the optimized design of its formulation, process, and structure. Among these factors, the grinding performance of the grinding stone serves as a tangible representation of its operational efficacy, garnering significant attention from researchers. Currently, grinding stone performance verification equipment can be categorized into six types based on differences in the relative action forms between the grinding stone and rail: 1) traditional grinding machine type; 2) stationary block rail type; 3) linear rail feed type; 4) circular rail horizontal rotary feed type; 5) high-speed rail grinding stand; and 6) real rail grinding test line.

(1) Conventional Grinder Type. Uhlmann et al. [1] investigated the impact of grinding parameters on the surface quality (hardness, roughness, white layer thickness) of rails using a surface grinder depicted in Figure 1. Wu et al. [2] verified that a slotted grinding stone enhances the surface quality of the rail after grinding using a similar device. This type of grinding tester is characterized by a high grinding stone line speed (up to 30-50 m/s) but a low feed rate (8-16 m/min) [2]; simultaneously, the grinding pressure is non-adjustable. Consequently, this tester cannot simulate actual rail grinding operations and can only provide a reference for studying grinding wheel behavior.

Fig.1 Surface grinding machine testing machine[1]

(2) Stationary Block Rail Type. Based on the field operation mode of grinding stones for rail grinding, numerous scholars connected the motor to the grinding stone and utilized the end face of the grinding stone to grind the rail workpiece. Kanematsu et al. [3] verified the grinding performance of various grinding stones using the rail grinding tester shown in Figure 2. Gu et al. [4] modified a grinding tester with a similar structure using a friction experimental tester to study the grinding performance of grinding stones with different abrasive grain sizes. This type of testing machine can better simulate the rotational speed of the grinding stone, grinding pressure, and other parameters but cannot achieve the grinding feed movement. Prolonged grinding of a local rail area will elevate the interface temperature due to grinding heat, leading to performance degradation of resin-bonded grinding stones at high temperatures and decreased abrasive holding power. Additionally, under the influence of grinding heat, the rail is prone to burning. Therefore, the experimental process of this type of testing machine must fully consider the interference of grinding temperature on the experimental results.

Fig.2 Block Rail Fixed Grinding Tester[3]

(3) Linear Rail Feed Type. To address the rail feeding issue in the rail grinding test machine of Gu et al. [4], Zhou Kun [80] used a rack and pinion to drive the bar rails, enabling unidirectional, linear rail feeding from 1.6 to 4.0 km/h, as shown in Figure 3. The experimental machine was also utilized to study different grinding parameters (grinding pressure [5], feed rate [6]) and grinding wheel hardness [7]. Huang Guigang [8] modified the main structure of the BM2015 gantry planer to develop a vertical rail active grinding tester, depicted in Figure 4. The equipment used 60 kg/m gauge rail on-site, with a simulated feed speed of 0.3~4.5 km/h, and could achieve grinding of ±50° gauge angle. The equipment successfully verified the grinding performance of the developed CBN grinding wheel. The rail active grinding operation speed ranges from 3~24 km/h, while the speeds simulated by this type of rail grinding equipment are lower, limiting its experimental capacity.

Fig.3 Horizontal Linear Rail Feed Grinding Tester[5,6,7]

Fig.4 Vertical Linear Rail Feed Grinding Tester[8]

(4) Circular Rail Horizontal Rotary Feed Type. The Chinese Academy of Railway Sciences [9], Nanjing University of Aeronautics and Astronautics [10,11], and Kuffa et al. of Switzerland [12] reported a circular rail horizontal rotary feed tester, shown in Figure 5. In this tester, the rails are machined into a disc and arranged horizontally; the rail disc can rotate horizontally under the action of the drive mechanism to simulate the feed speed of the grinding car. The equipment designed by the Chinese Academy of Railway Sciences features a rail disc diameter of approximately 1.6 m, a grinding belt width of 10 mm, and a maximum grinding speed of 10.8 km/h [9]. Based on the grinding effect of this experimental equipment, it provides data support for the development of ordering conditions for active grinding wheels [9,13,14]. This type of equipment is well-known in the field of active rail grinding.

Fig.5 Cyclical Rail Horizontal Rotation Feed Grinding Tester[19]

(5) High-Speed Rail Grinding Tester. Wang Hengyu's team at Southwest Jiaotong University [15,16] designed a passive high-speed rail grinding tester capable of simulating a maximum grinding speed of up to 60~80 km/h, as shown in Figure 6. Additionally, Professor Zou Wenjun's team at Henan University of Technology [17,18] designed a small high-speed rail grinding tester (Figure 7), where the rail wheel disc is arranged vertically, and the equipment can adjust the grinding stone impulse and grinding pressure. The outer diameter of the rail is 150 mm, and the specification of the grinding stone is Φ80×10×10 mm, capable of simulating on-site grinding speeds of 60~80 km/h and grinding pressures of 1200~3200 N. The grinding pressure of the grinding stone can be adjusted up to a maximum grinding speed of 60~80 km/h, with a maximum grinding pressure of 3200 N. This type of experimental machine plays a crucial guiding role in the development of high-speed grinding stones.

Fig.6 High-speed grinding bench[13]

Fig.7 High-speed grinding reduction test bench[16]

(6) Real Rail Grinding Test Line. Over the past decade, Golden Eagle Heavy Industry has embarked on the development and innovative design of high-speed rail grinding cars and established a rail grinding test base in Yujiahu, Xiangyang City, Hubei Province. Figure 8 depicts a high-speed rail grinding car, which can be equipped with 24 grinding wheels (12 on each side), operating at a grinding speed exceeding 60 km/h [15]. The vehicle's operating conditions and modes can fully align with those of high-speed rail grinding, enabling the verification of the grinding stone's cutting performance. Simultaneously, the vehicle is equipped with multiple grinding stones, allowing for the verification of the stability of the grinding stone production process. Therefore, under the condition of establishing a comprehensive evaluation system, the future evaluation and verification of grinding wheel performance by this grinding car hold authoritative guiding value.

Fig.8 Test line real car grinding[13]

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