On June 25,  at the track-laying base of the Maribaya Port of the Guinea Massi Railway, with Zhang Cheng, General Manager of the Simandou Railway Company of the Winning Alliance, pressing the start welding button of the intelligent fixed flash welding machine, it marked the official commissioning of Africa's first intelligent rail welding production line at the Guinea Massi Railway, which was invested and constructed by the Compagnie des Travaux Généraux de la Côte d'Ivoire (CTG) and built by China Railway First Group.

Zhang Cheng, General Manager of the Simandou Railway Company of the Winning Alliance, initiated the welding machine

It is understood that the MXTJ-01 bid section of the Guinea Massi Railway undertaken by China Railway First Group is responsible for the prefabrication and erection of 1,710 T-beams, the laying of 289.14 kilometers of main line tracks, and the laying of 61.06 kilometers of station tracks. It is estimated that a total of 24,000 joints will need to be welded. After the commissioning of the rail welding line, it will undertake the welding of approximately 22,000 joints, significantly reducing the welding workload at the construction site.

To meet the needs of mechanized track-laying construction for the Massi Railway project, this rail welding production line adopts China's advanced UN5-150G1 fixed flash welding machine, GDZH-120 rail heat treatment machine, RWCM-2500-A four-way straightening machine, and other automated tooling equipment and new technologies, realizing industrialized, intelligent, informatized, and green rail welding. This significantly improves welding quality and efficiency, ensures high-quality tracks and smooth train operation after the laying of long rails, and promotes China's advanced rail welding equipment, technologies, and standards to go global.

First welding of the rail welding production line

Among them, the UN5-150G1 fixed flash welding machine adopts four-axis guided upsetting and adds a pressure-holding step to push out the tumor, making the welded rail straighter and greatly improving the appearance and welding quality of the rail after welding. This equipment is suitable for welding under different working conditions of ordinary and quenched rails, with stable welding performance, high efficiency, and a post-welding air-blowing function, achieving multi-purpose use. The GDZH-120 rail heat treatment machine adopts dual-frequency heating technology to realize fully automatic temperature control and frequency conversion. The RWCM-2500-A four-way straightening machine uses laser sensors to detect the straightness of the rail and generate a straightness curve, achieving human-computer interaction visualization, which is convenient for operators to straighten the rail.

"To directly lay long rails onto the tracks, we 'relocated' domestic rail welding factories to Guinea. On-site, 25-meter standard rails are welded into 300-meter long rails through the rail welding production line, and then advanced new multi-functional long rail tractors from China are used for mechanized long rail laying. This is the first time for China Railway First Group in overseas projects and represents the advanced technological level and the practice of new productivity of Chinese enterprises in Guinea's modern railway construction," introduced Cao Dezhi, the person in charge of the track-laying and bridging project of the Guinea Massi Railway of China Railway First Group. Compared with welding long rails on-site, factory welding of long rails not only saves manpower and operating time but also reduces harmful soot emissions, greatly improving the efficiency of long rail laying.

Aerial view of the rail welding base

"To improve the operating efficiency of the rail welding line, we have set up 14 stations according to the assembly line operation mode, including rust removal, welding machine, air cooling, coarse grinding, normalizing, water cooling, straightening, fine grinding, water cooling, flaw detection, and equipped with two sets of group cranes and two rail storage positions. At the same time, in response to Guinea's humid and rainy weather, we have specially built drying area sheds and rainproof sheds, which not only improve the production capacity and storage capacity of the rail welding line but also ensure normal welding during the rainy season," introduced Fan Fugui, the person in charge of the construction site.

"During the rail welding process, the rail end faces are resistively heated to above 1,200°C and then welded into one through upsetting extrusion. It takes approximately two minutes to form a seamless connection, and a welding head can be completed in six minutes," introduced Chen Hong, the technical person in charge at the site. After welding the rail joints, normalizing treatment is required. By reheating at 900°C, the internal grains of the steel are refined, improving the toughness of the rail welding head and increasing the service life of the rail.

Since the construction of the rail welding production line began on May 9, the project department has strengthened construction organization, coordinated resource allocation, and focused on the "ensuring safety, competing in skills, striving to be a pioneer" safety year labor competition activities around the established construction schedule goals. They seized the golden construction time before the rainy season and fully promoted the construction progress of the rail welding line. During this period, the project department invited technical personnel from the rail welding manufacturer to provide on-site guidance throughout the process and worked continuously for more than 40 days to successfully complete the construction of the rail welding production line plant, the installation of group cranes, the construction of rail storage positions, and the installation of rail welding line equipment, ensuring the smooth assembly and commissioning of the intelligent rail welding production line and laying a solid foundation for accelerating the construction of the Massi Railway track project.

Source: China Railway First Group New Transportation Company