CCTV News: At present, the world's fastest high-speed rail CR450 EMU is undergoing type tests. The braking system of high-speed rail trains has always been the focus of technological innovation. Our technical workers have also overcome extreme problems with their superb skills and persistent research, and have continuously surpassed them. In the series of reports on "Craftsmen of Great Powers", let's meet a CNC turning worker - Zhang Hongbin.

6500 meters, 112 seconds, this is the braking distance and time that the world's fastest high-speed rail - the CR450 EMU must achieve from a speed of 400 kilometers per hour to 0. What Zhang Hongbin is creating is the key component of the EMU braking system - the brake disc hub. Zhang Hongbin, senior technician of Railway Science and Technology Zongheng (Tianjin), a group company of the Institute of Railway Science and Technology Group: "We railway workers have a saying that we are not afraid of the car not being able to run, but fear of the car not being able to stop. This sentence shows the importance of train braking."

In 2012, the "Fuxing" of China's standard EMU, officially launched research and development. If the conventional process is followed, the first thing to do is to introduce a high-precision grinder to process the inner hole of the disk hub, and a commissioning preparation cycle must be reserved, which will greatly slow down the trial production progress and thus affect the entire project. A bold idea was born in the mind of Zhang Hongbin, who was only 26 years old at the time. Can you try it with your turning skills? Zhang Hongbin said: "There are still voices of opposition. They don't believe it. They think that it is impossible to process the grinder with a lathe. There is a saying that a newborn calf is not afraid of a tiger. Another thing is that he is actually holding his strength."

The accuracy of the wheel hub must reach 0.005 mm, which is only one-sixteenth of the hair. Zhang Hongbin often stands next to the lathe for more than ten hours, exploring the amount of tooling, adjusting the speed, and even distinguishing the cutting state of the lathe by listening to sounds. "If you listen with your ears, judge the vibration of the parts and whether the tip of the knife is worn. I feel that the machine tool and I are in a state of communication," he said.

Try 7 different structural tools and change 9 tool paths. More than three months have passed, and they have not only broken through the key technology of lathe production of "Fuxing" brake disc hubs, but also reduced one process, which doubled the efficiency of grinding processing abroad.

If the wheel hub is the "power responsibility" of the high-speed rail braking system, the wedge pin is the "safety lock" when the train stops. When testing the brake device of the CR450 EMU sample vehicle, this small part less than 5 cm tall surprised Zhang Hongbin, who had been through many battles, "As soon as the tool is processed, the tip of the knife collapses. Is the material of this part harder than the material of the tool?"

The new materials bring new challenges. Starting from the optimization and polishing of special-shaped tools, Zhang Hongbin innovated the arc-surface processing CNC technology and installed the new wedge-shaped pins into the brake clamps of the CR450 EMU sample car with tight wires.

From catching up to leading, China's high-speed rail has always set records with a spirit of self-transcendence, and Zhang Hongbin and his team have also pushed the accuracy in their hands to new heights again and again. Zhang Hongbin said: "The parts he processed were installed on the "Fuxing" and Mercedes-Benzing on the vast land of the motherland, and that sense of pride arises naturally. The construction of a strong transportation country is also achieved by front-line workers one by one."