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【Rayclass | 锐课堂】Laser Cleaning 1+1>2
Date:2019-08-16Source:Original article

轮对是机车车辆与钢轨相接触的部分,由左右两个车轮牢固的压装在同一个车轴上组成。轮对的作用是保证机车车辆在钢轨上的运行和转向,承受来自机车车辆的全部静、动载荷,把它传递给钢轨,并将因线路不平顺产生的载荷传递给机车车辆各零部件。

The wheelset is the part of the locomotive that is in contact with the rail, and is composed of the left and right wheels firmly pressed on the same axle. The role of the wheel pair is to ensure the running and steering of the rolling stock on the rail, to withstand all static and dynamic loads from the rolling stock, to transfer it to the rail, and to transfer the load generated by the uneven line to the parts of the rolling stock.

 

对于高铁动车来说,车轮和车轴都是用没有添加合金元素的碳素钢制造的,而这往往会成为发生裂纹和脆性断裂的原因,因此,高铁在运行一段时间后都需要进行检修。在检修前,需要将轮轴及轮辐上的涂层彻底剥离下来,传统的方法是采用钢丝刷进行打磨,此方法虽然可剥离涂层,但是效率很低,并且作业人员劳动强度很大,还会对轮对表面造成损伤,以至于对下一步的探伤造成影响。

For high-speed trains, the wheels and axles are made of carbon steel without alloying elements, which tends to be the cause of cracks and brittle fractures. Therefore, high-speed rails need to be repaired after a period of operation. Before the inspection, the coating on the axle and the spokes needs to be completely peeled off. The traditional method is to use a wire brush to polish. Although this method can peel off the coating, the efficiency is very low, and the labor intensity of the operator is large. Damage to the wheel surface is affected, so as to affect the next flaw detection.

 

高铁动车轮对图

图片来源于网络

 

激光清洗技术能有效清除轮对表面漆层,但效率偏低,厚涂层情况下清洗速度慢,局限性很大,针对目前使用的清洗方法的不足,同时也为了扩大激光清洗的应用范围,提高清洗质量、效率以及避免单纯脉冲激光清洗的局限性,研发出新的清洗工艺:

 

脉冲激光和半导体激光复合清洗技术

 

激光复合清洗技术的优点不单单是两种激光的叠加,重点体现在能量的利用率远远大于两种热源的简单相加。

Laser cleaning technology can effectively remove the surface paint layer of the wheel, but the efficiency is low, the cleaning speed is slow under the condition of thick coating, and the limitation is very large. In view of the shortcomings of the currently used cleaning methods, and in order to expand the application range of laser cleaning, improve the cleaning quality, efficiency and avoid the limitations of pure pulse laser cleaning, a new cleaning process has been developed. The advantage of laser composite cleaning technology is not only the superposition of two kinds of lasers, but the emphasis is on the utilization of energy is much larger than the simple addition of two heat sources.

 

激光复合清洗原理

 

激光复合清洗技术是激光清洗的又一新发展方向,是通过脉冲激光与半导体激光相互作用形成的一种增强适应性的清洗方法,在处理基材表面附着物(污垢、氧化皮、锈斑、有机涂层等)过程中,半导体激光大光斑辐照附着物表面,表面吸收能量均等分布的激光产生热能,使金属材料和附着物之间形成热膨胀压力,降低两者之间结合力。当脉冲激光输出高能激光束时,产生的振动冲击波直接使结合力不强的附着物脱离金属表面,实现激光快速清洗。

Laser composite cleaning technology is another new development direction of laser cleaning. It is an enhanced adaptive cleaning method formed by the interaction of pulsed laser and direct diode laser. In the process of treating the attachments on the surface of the substrate (dirt, scale, rust, organic coating, etc.), the direct diode laser irradiates the surface of the deposit with a large amount of laser energy that is equally distributed on the surface to generate thermal energy, forming a thermal expansion pressure between the metal material and the attachment to reduce the bonding force. When the pulsed laser outputs a high-energy laser beam, the generated vibration shock wave directly causes the adhesion of the bonding force to be detached from the metal surface, thereby achieving rapid laser cleaning.

 

与其他激光器相比,半导体激光器光斑能量分布均匀,能够实现激光能量缓慢下降呈梯度变化,半导体激光器在清洗过程中作为热传导输出,通过调节激光功率和辐射时间熔化和加热金属材料附着物,使金属材料和附着物之间形成热膨胀压力,减小两者之间结合力,附着物更容易脱离金属表面,实现激光清洗。

Compared with other lasers, the direct diode laser has a uniform spot energy distribution, which can achieve a slow gradient of laser energy, and the direct diode laser acts as a heat conduction output during the cleaning process. By adjusting the laser power and radiation time, the metal material attachment is melted and heated. The thermal expansion pressure is formed between the metal material and the attachment, and the bonding force is reduced, and the attachment is more easily separated from the metal surface to achieve laser cleaning.

 

激光复合清洗原理图

 

 

实际应用案例

 

为了体现激光复合清洗技术相对于激光清洗技术的优势,我们进行了轮对涂层除漆清洗测试,同时采用500W脉冲激光清洗对比300W脉冲激光搭配1500W半导体激光器进行清洗测试,设备和实验样品信息如下:

In order to reflect the advantages of laser composite cleaning technology compared to traditional laser cleaning technology, we carried out the wheel-to-coat coating paint cleaning test, while using Raycus 500W pulsed fiber laser cleaning and 300W pulsed fiber laser with 1500W direct diode laser for cleaning test, equipment and experimental sample information are as follows:

清洗要求:

request for cleaning is:

1

清洗过程中不能出现氧化条纹;

Oxidation fringes cannot occur during cleaning;

2

清洗一根轮对轴的时间控制在10min内;

The time for cleaning a wheel-to-shaft is controlled within 10 minutes;

在激光复合清洗测试之前,需要对轮对轴表面的双组分环氧树脂进行测厚,分别测试轴的四个区域的厚度,然后计算平均厚度,如下表所示:

Before the laser composite cleaning test, it is necessary to measure the thickness of the two-component epoxy resin on the surface of the wheel-to-shaft, respectively test the thickness of the four regions of the shaft, and then calculate the average thickness, as shown in the following table:\

 

针对厚度为150-250μm环氧树脂涂层材料,我们做了如下两组测试:

For epoxy coating materials with a thickness of 150-250μm, we have done the following two tests:

 

测试

01

500W脉冲激光清洗环氧树脂涂层材料时,使用焦距为160mm的场镜,扫描速度为6m/s,重复频率选择20KHz,扫描宽度为80mm,210r/min,每分钟轮对的转速为210转。

When the 500W pulsed fiber laser cleaning epoxy coating material, the field lens with a focal length of 160mm is used, the scanning speed is 6m/s, the repetition frequency is 20KHz, the scanning width is 80mm, 210r/min, and the rotation speed per minute is 210rpm.

 

500W

脉冲光纤激光器

清洗后测量了轮对正面和反面的温度,分别为40℃和30℃,清洗效率为1.5m²/h。清洗效果图片如下图:

After cleaning, the temperatures of the front and back sides of the wheel pair were measured, 40 ° C and 30 ° C, respectively, and the cleaning efficiency was 1.5 m ² / h. The cleaning effect picture is as follows:

 

测试

02

300W搭配1500W半导体激光器清洗环氧树脂涂层材料时,扫描速度为8m/s,扫描宽度为80mm,占空比为20%,调制频率为2000Hz,半导体激光光束与脉冲激光光束间的间隔设置为3mm.

300W pulsed fiber laser cleaning with 1500W direct diode laser cleaning epoxy coating material, the scanning speed is 8m / s, the scanning width is 80mm, the duty ratio is 20%, the modulation frequency is 2000Hz, the interval between the semiconductor laser beam and the pulsed laser beam is set to 3mm. 

 

300W

脉冲光纤激光器

1500W

光纤输出半导体激光器

清洗后测量了轮对正面和反面的温度,分别为39℃和30℃,清洗效率为8.5m2/h。清洗效果图片如下图:

After cleaning, the temperatures of the front and back sides of the wheel pair were measured, respectively 39 ° C and 30 ° C, and the cleaning efficiency was 8.5 m 2 / h. The cleaning effect picture is as follows:

 

结论

 

根据测试实验效果及数据分析,我们得出如下结论:

Based on the test results and data analysis, we draw the following conclusions:

1

300W脉冲搭配1500W半导体激光复合清洗在效率、效果上均能达到预定清洗的要求;

300W pulsed fiber laser cleaning with 1500W direct diode laser composite cleaning can meet the requirements in efficiency and effect;

2

采用脉冲激光-半导体激光复合清洗技术可进行较厚涂层材料清洗,快速并有效的提高清洗质量,基材不容易造成损伤。

The laser composite cleaning technology can be used to clean thick coating materials, improve the cleaning quality quickly and effectively, and the substrate is not easy to cause damage.

【Rayclass | 锐课堂】TIPS

 

在复合清洗建议采用调制模式来清洗涂层,连续模式输入热量过大,会造成工件的热变形,此次测试采用调制模式进行清洗,工件表面的温度低于45℃,这个温度不会对轴有所影响;

In the composite cleaning, it is recommended to use the modulation mode to clean the coating. If the continuous mode input heat is too large, the workpiece will be thermally deformed. This test uses the modulation mode for cleaning. The surface temperature of the workpiece is lower than 45 °C. This temperature does not affect the axis.

 

在复合清洗过程中,建议采用脉冲激光与半导体激光光束间隔3-5mm,用以减少热累积和提高清洗效率。

In the composite cleaning process, it is recommended to use a pulsed laser to be separated from the semiconductor laser beam by 3 to 5 mm to reduce heat accumulation and improve cleaning efficiency.

 

 

 

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