Xia Li, male, born in July 1971, Han nationality, mass, fitter in the 54th Research Institute of China Electronics Technology Corporation.

As the person in charge of communication antenna assembly, Xia Li has successively undertaken the tasks of pre-research, assembly and calibration of satellite antennas such as "Eye of the Sky" radio telescope, Chang ‘e-4 satellite, Somali escort warship, and communication facilities on the "9.3" military parade. The assembled gear gap is only 0.004 mm. The occupation is novel and the precision is high.

Honors won: national technical expert, gold medal worker in Hebei Province, May 1st Labor Medal in Hebei Province, and 2016 military craftsman in Hebei Province.

Xia Li, male, born in 1971, Han nationality, mass, fitter, senior technician of the 54th Research Institute of China Electronics Technology Corporation, responsible for antenna assembly of aviation and aerospace communication, the first high-skilled leader of China Electric Power Department, established Xia Li Innovation Studio in June 2016. Won the national technical expert in 2016, the gold medal worker in Hebei Province, the May 1st Labor Medal in Hebei Province, the great craftsman in Hebei military industry, and the representative of the great craftsman in the national defense post and telecommunications industry in Beijing Millennium Monument in 2017. He is a locksmith, but in the research institute where doctors gather together, whether the drawings designed by doctoral engineers can be implemented or not depends on his opinions. For more than 20 years, Xia Li has been dealing with these semi-finished communication equipment every day. In terms of production and assembly technology, Xia Li has overcome one difficulty after another and created one miracle after another.

Challenge the gear clearance of 0.004 mm — — The story of assembling the ultra-high precision antenna of the first radio telescope in Asia

384,400 kilometers is the average distance from the earth to the moon.

0.004 mm, which is the distance between the gears of the antenna of the largest radio telescope in Asia, and is equivalent to 1/20 of the thickness of a hair.

These two figures, which are calculated by hundreds of millions, are closely linked together because of the "Chang ‘e Falls on the Moon" project, and it is Xia Li, a senior fitter in the 54th Institute of China Electronics Technology Group Corporation who connects them together.

Shanghai 65-meter radio telescope ranks fourth in the world and first in Asia. The silver telescope stands at the foot of Sheshan Mountain in Shanghai, magnificent under the blue sky. Because the construction involves many technical fields, this large radio telescope is the embodiment of the country’s scientific and technological strength.

In order to achieve high sensitivity and accurate pointing, the gear gap of azimuth and pitch control device, the core component of telescope antenna, should reach 0.004 mm. It is Xia Li, who has nearly 30 years of locksmith experience, who has completed this "impossible task".

"Modern technology has automated many precision manufacturing, but to achieve this ultra-high precision assembly, it is inseparable from the manual operation of highly skilled workers. Xiali is completely ‘ Rong ’ Into the assembly of satellite antennas. " Xia Li’s colleagues sincerely admire.

Walking into the workshops of the process and manufacturing rooms of 54 antenna servo departments where Xia Li is located, thousands of square meters of workshops are full of various types of satellite antennas being assembled. The satellite antennas contracted by 54 are basically made here, and Xia Li is the skill leader.

Since entering 54 institutes in 1987, Xia Li has participated in the pre-research and assembly of satellite antennas in many major national projects in the past 30 years. "The most difficult thing is the assembly of the antenna of the Shanghai 65-meter radio telescope." He said.

Radio telescope determines the structure of distant celestial bodies by receiving radio waves from celestial bodies. Soft landing of Chang ‘e-3 moon and orbit determination of Chang ‘e-5 flight tester … … Not only does it receive signals and send instructions in China’s lunar exploration project, but the Shanghai 65-meter radio telescope also "stares" at the more distant deep space, and is vividly called "Tianma Telescope".

It is Xia Li’s pride to let "the sky soar". Because the assembly was too difficult, 54 handed the task to him.

The radio waves in the universe have different wave bands. The antenna of a telescope is like the nose and ears. By scanning up and down from left to right, the signals in different wave bands can be accurately found and received. Even if they deviate by only a few percent, the target may not be found. The device that controls the antenna to scan all angles is called azimuth pitch control device, and its core is a circular steel coded disk with a diameter of 200mm and a thickness of 10mm.

To ensure the accurate detection of the telescope, it is the key to install the steel code wheel. The gear clearance should be 0.004 mm. If it is too small, the antenna will not turn, and if it is too large, the antenna will loosen.

A trace is 0.01 mm. A hair thread is about 8 threads thick, while 0.004 mm is only 1/20 of a hair thread. To achieve accurate assembly, Xia Li said that the most important thing is "peace of mind", and there is only equipment in the eyes and heart. When screwing the screw, hold your breath. If your hand is a little heavier, it will be too tight, and your hand strength will not be enough to meet the accuracy requirements. "It is easy to meet the assembly accuracy requirements by repeatedly measuring, finding the movement deformation of parts and finding the law." In repeated attempts, he looked for the unspeakable "encounter" with his accumulated touch for many years.

Xia Li is faced with more than one problem in installing the steel code plate. The steel encoder should be installed on a pallet, and the flatness of the pallet is extremely high, which is a few thousandths of a millimeter. At that time, the processing capacity of grinder equipment could only reach a few hundredths of a millimeter, and the accuracy grade was 10 times different. He decided to grind it by hand. Using two dial indicators to measure the surface of the tray little by little, and comparing and analyzing all the data, in three days, he grinded the height difference of the tray plane to 0.002 mm, and successfully completed the assembly task.

Escort Ship Communication and Craftsman’s Pursuit in "Eye of the Sky"

It is difficult to install the ultra-high precision astronomical telescope antenna on land. Installing an antenna at sea is more difficult.

China’s naval escort mission to the Gulf of Aden and Somali waters shows China’s image as a responsible big country. Escort ships are also inseparable from satellite communications. In addition to demanding accuracy, in the Somali waters in summer, the temperature of the ship’s deck can reach 50℃, the ship-borne communication antenna is in high temperature, the escort ship shakes greatly under the impact of waves, and the air is corrosive. In complex sea conditions, to keep the antenna running stably, Xia Li led the team to design a brand-new core component of the 1.2-meter antenna, which is smaller in size, but the data transmission capacity is equivalent to the sum of the previous two or three shipborne antennas. They were praised by users because they created a record of continuous work for six months without stopping.

As a fitter, as long as the equipment is accurately assembled according to the designer’s drawings, the task is successfully completed. But Xia Li is more than that. As a technical leader, he often appears in the technical analysis meeting of new product pre-research.

The world’s largest single-aperture radio telescope — — The 500-meter spherical radio telescope is being installed in a "Dawodang" in Guizhou. After completion, it will maintain the status of world-class equipment in the next 20 to 30 years. The antenna of this telescope also contains Xia Li’s wisdom. 54 won the bid for the assembly of this super telescope antenna. When bidding, 54 need to provide an antenna structure. In the pre-research and assembly of structural parts, Xia Li and others put forward some suggestions to modify many unreasonable places to make the assembly go smoothly.

These assembly robots cannot be replaced.

"At present, the degree of automation of mechanical equipment is very high, but the types of fitters have not disappeared because of the need for ultra-high precision assembly in special environments and special structures, which machinery cannot do." Xia Li said.

The installation of communication antenna is to assemble all components. In the eyes of outsiders, in the industrial era, the assembly of industrial products should be completed on the assembly line or by robots. Like Xia Li and the workers’ masters, it seems that it is not modern enough to combine parts with both hands.

"The work on the assembly line is purely mechanical labor, and it doesn’t need brains. This is not the case here." Xia Li said that they are different from the assembly line that everyone knows, and these assembly jobs cannot be replaced by robots.

The production and assembly workshop is to turn the designer’s drawings into products. In fact, many times, the designer’s drawings will encounter many problems in actual production and processing.

Therefore, workers’ masters should not only know how to read drawings, but also encounter various problems in the process of landing the contents of drawings, which are the most direct obstacles. Even, the frequency and speed of rotation of some individual components are determined by the hand feeling formed by the long-term accumulation of workers and masters.

As a teenager, Xia Li showed strong hands-on ability and curiosity about things, and grew into a "skillful hand" in the eyes of neighbors and colleagues. Coincidentally, Xia Li took up a job he was interested in. Before he was 17, Xia Li entered 54 schools and became an apprentice locksmith. Today, for more than 20 years, Xia Li has been staying on the bench of 54 fitters, using electric drills, wrenches and pliers to ensure the quality of military products handled-the pass rate is 100%.