Carving a knife with gunpowder (pioneer of the times) —— A record of Xu Liping, a special aerospace technician.

　　Information photo

　　Xu Liping, a special aerospace technician, is a powder shaper in the combustion chamber of solid rocket engine in 7416 Factory of the Fourth Research Institute of China Aerospace Science and Technology Corporation.

　　Since he joined the work in 1987, he has been engaged in the extremely dangerous micro-shaping work of the solid power fuel surface of the space engine, which is called "working in the explosive pile". Over the past 30 years, Xu Liping has been praised as "a great craftsman who carves gunpowder" because of his exquisite skills, professional attitude and dedication, and has been awarded the honors of "Top Ten Touching People", "Model of Sanqin", China Skills Award, National May 1 Labor Medal and "Touching China" in 2015.

　　"Plastic experts" in dangerous positions

　　Solid rocket engine is the "heart" of missile weapons and equipment. The size and accuracy of the burning surface of engine propellant directly determine the flight trajectory and precise range of the missile. Burning surface shaping is still a worldwide problem, and no matter how sophisticated the machine is, it still cannot completely replace labor.

　　In 29 years, more than 10,000 days and nights, Li Xu Ping and his colleagues have been doing one thing attentively, "micro-shaping the engine powder surface, and finely trimming the solidified propellant powder surface with special tools according to the technological requirements to meet the various complex requirements of missile flight."

　　Xu Liping’s work requires extremely high accuracy, "and compared with accuracy, the high risk of this position is even more daunting". He said that the particularity of solid fuel makes the operator lie on the explosive bag during plastic surgery. Once the cutter accidentally touches the metal shell or the friction is too large, it will cause combustion or even explosion in an instant. At a high temperature of several thousand degrees, the operator has no chance to escape safely.

　　"In 1987, I was less than 19 years old. After graduating from a technical school, I went to work in the charge shaping workshop where my mother once worked. Although I was fully prepared, I was stunned by the huge roar and mushroom clouds in the first class. I didn’t expect it to be so dangerous," Xu Liping recalled.

　　This class left a deep memory for him. From then on, he made up his mind that to avoid danger, he had to be bold and cautious and practice the knife in his hand.

　　Because the solid powder has strong toughness and contains coarse particles, it is difficult to grasp the force of using a knife. If it is cut across the board, it is difficult to keep the powder surface flat. Once it is cut too much or left with a knife mark, the powder surface accuracy does not match the design, and the powder cannot burn according to the predetermined direction, resulting in the engine deviating from the track and even exploding. The surface of the medicine is uneven, and how much to cut with a knife each time depends on the judgment of skilled personnel. In order to practice kung fu on his hands, Xu Liping kept pondering and practicing how to use force and how to cut the knife, gesticulating with basic skills such as cutting, cutting and shoveling, trying to figure out the cutting amount, cutting angle and cutting force of the knife, and his arm was sore. He was even more meticulous in his post operation, humbly asked for advice, and studied hard and practiced one knife at a time. Over the years, he practiced more than 30 knives, but his hands felt more and more, and the smoothness of the medicine surface was getting higher and higher. Later, when he touched it with his hand, he knew how to trim the medicine surface that met the design requirements, and the products after his plastic surgery maintained a 100% qualification rate.

　　An innovator in the first-line workshop

　　Due to the needs of national defense construction, the fuel used in space solid rocket engines is getting higher and higher in energy. One expert described the risk as follows: "With a small steel ball rolling half a meter along the powder surface, these highly sensitive gunpowder will be ignited, and its burning temperature can reach thousands of degrees."

　　How to better improve the cutting tool, improve the plastic efficiency and ensure the safety is a problem that Xu Liping has been thinking and studying. He secretly vowed to develop a more useful and scientific cutting tool to avoid danger.

　　After continuous exploration and practice, he designed, manufactured and improved dozens of tools according to different types of engines, different stages and different parts of plastic surgery, of which nine applied for national patents, two were authorized, one won the Innovation Award of Shaanxi National Defense Science and Technology Industry Workers, and the other was named "Flat Knife" by the unit, which greatly improved the work efficiency and ensured the operation reliability and quality stability.

　　Since 2005, although it can’t completely replace manual operation, the factory has been trying to introduce and popularize advanced numerical control technology. For this reason, the factory has introduced the largest vertical shaping machine in China. However, there is no experience to learn from in applying such advanced technology to drug surface shaping, and the process of familiarity and use is far more difficult than imagined.

　　Xu Liping participated in the equipment installation from the beginning. "According to his years of work experience, he put forward more than 20 suggestions for modification, such as modifying the chip suction device and installing the interlocking device, and compiled the shaping program of the shaping machine to make the equipment performance better meet the post requirements."

　　Through unremitting efforts, Xu Liping gradually explored the shaping parameters suitable for all kinds of burning rate propellants, and designed special shaping tools for special profiles. The successful application of numerical control shaping machine under his leadership in the shaping process of propellant surface has filled the gap in China.

　　A fearless pioneer at a critical moment

　　Choosing a plastic surgery post means choosing to associate with danger and keep company with death.

　　"On one occasion, a key engine in China entered the critical stage of development, and two engines failed in the test run in succession, and another engine about to be tested was once again debonded." Xu Liping recalled that in order to thoroughly investigate the reasons, the expert group resolutely decided to dig drugs on the spot and look for the "root cause" without advanced testing equipment.

　　Digging medicine on the spot means drilling into the engine combustion chamber that has been filled with strong propellant, and digging out the solidified explosives, and the amount of digging medicine is extremely large, which is the first time in the history of the factory. It is difficult to imagine, and the danger is self-evident.

　　However, without any hesitation, a commando team with an average age of early 30 years old quickly formed. The leaders of the institute and factory were the first to drill in to check the situation, the experienced team leader drilled holes to find out the location, and the workshop director became the "first operation". Xu Liping also volunteered to join in and became the youngest commando.

　　Narrow space, half lying and half kneeling in tons of explosives, endured the strong and pungent smell, and the commandos carefully dug with wooden shovels and copper shovels. The high tension and lack of oxygen make each person only work in it for more than ten minutes at a time. As the youngest commando, Xu Liping always insisted on a few more minutes every time he went in. "At that time, in addition to the rustling of medicine, he could hear his nervous heartbeat."

　　In this way, like ants moving, it took more than two months to dig out more than 300 kilograms of propellant, successfully found the cause of the failure, and the repaired engine ground test was a complete success. After the task, Xu Liping’s legs were so painful that he could hardly walk. "As long as the organization and the task need it, I will still not hesitate to go to the ground!"