"What determines the accuracy of the servo motor is the encoder."
"There are three main types of encoders, optical encoders, magnetic encoders, and capacitive encoders. Among them, optical encoders are the most widely used and are more trustworthy in terms of accuracy."
After collecting all the knowledge about encoders, Lin Xiao chose his own purpose.
The encoder can provide feedback on the movement of the servo motor, and then use this feedback to further control the accuracy of the servo motor. Therefore, if you want to break through the servo motor, you need to optimize the encoder.
What determines the quality of the encoder is first of all related to the elastic material inside the encoder. However, in terms of materials, Huaguo obviously still has certain weaknesses. The second is the internal structure of the encoder and the control of the computer algorithm.
Excellent structure can be optimized even if the material is not good.
Of course, for Lin Xiao, the material of the encoder is not a problem, because the photolithography machine in his mind and all the structures of the servo motors in it are clear to him.
So there is no problem in directly copying it, but again, copying is not his character. He not only wants to build a photolithography machine, but also a better photolithography machine than foreign countries, and a better servo motor.
It means better precision, which will be very beneficial to the future production speed of photolithography machines.
By then their lithography machines will be better than Asmail's, and they won't sell them abroad. They will set up their own chip foundry in China, just like TSMC.
Of course, the ideal is lofty, and you still need to start doing it yourself.
"Then let's get Asmail's encoder up first."
Thinking of this, Lin Xiao directly opened the mechanical design software and started his own modeling.
Because he had a reference in his mind, he modeled very quickly. Before long, an encoder appeared in front of his screen.
"This is an incremental encoder. It can achieve 25,000 pulses per millimeter. It is worthy of being a foreign devil. It is really powerful."
Seeing this, Lin Xiao sighed slightly in his heart. Twenty-five thousand pulses per millimeter means that the distance change brought by the encoder for one pulse is one twenty-five thousandth of a millimeter, which is about 40 nanometers.
The resolution is equivalent to a quarter of that, which is 10 nanometers, and then combined with multiple encoders, the resolution can be reduced again to an even lower level.
This has to make people sigh with emotion, even Lin Xiao.
Of course, the emotion was emotion, and he did not forget his purpose.
"Well... as for this structure... there is still a lot of room for optimization."
Lin Xiao thought seriously.
For mechanical optimization, the most important test is the ability in physics, followed by the ability in materials science, and it just so happens that his levels in these two disciplines are relatively high.
So after a few brief glances, he roughly had several directions in his mind.
Then he began to modify the model on the 3D software in front of him.
For example, dichotomy.
The dichotomy method in mathematics can continuously obtain an approximate value. There is also a dichotomy method in physics, and there is also such a method in the application of structures.
By changing the internal structure of the encoder, if its own resolution is 10 nanometers, but if the internal structure is changed so that the distance change brought by each time is divided into two and becomes half of the original, then its resolution
It can reach 5 nanometers.
This is just Lin Xiao's temporary idea. How to optimize its structure still requires some research.
This is what he must study, because China cannot build such a sensor that can achieve 25,000 pulses per millimeter. Even if he has the structure and materials of foreign precision sensors in his mind, if he wants to make it, he needs another
technology in a field.
China's lagging behind in sensors has also restricted China's development in many industries, and it is obviously impossible for Lin Xiao to move from photolithography machines, to servo motors, to encoders, and finally to sensors.
So Lin Xiao could only find another way.
This is like a story: In order to detect whether there is soap in the soap boxes produced in the assembly line, a foreign soap factory invited automation experts to design, what kind of mechanical, microelectronics, and X-ray detection technology
After using it, the problem was successfully solved at a total cost of tens or millions of dollars.
But a soap factory in China also faced this problem, but obviously the owner of the factory didn't have that much money, so he hired experts and X-rays. So the engineers here thought about it and finally thought of it.
I came up with a method, put a large electric fan directly next to the production line, and the empty soap box would be blown away directly. If it is not empty, it cannot be blown away. So the problem was solved, and it cost a total of dozens of yuan.
.
This story is also Lin Xiao’s way of thinking about solving problems.
Use what China already has to achieve something that doesn't exist.
This is also a direction that many Chinese scientists are committed to research. Sometimes, if you are not careful, you can reach a level that even foreign countries envy. For example, the overall structure of an aircraft. Foreign materials are good, so the material strength can directly improve the fuselage structure.
The strength of China's materials is not good, so scientists have developed a technology for 3D printing aircraft structures. Although our materials are not good, because the 3D printed structures are completely integrated, there is no need for welding or rivets, so
The strength of the overall architecture should also be better.
Another example is that the noise of China's nuclear submarines has been ridiculed by foreign countries in the past. As a result, Chinese scientists developed a shaftless pump technology, which made China's nuclear submarines truly "quiet".
Therefore, Lin Xiao is now taking the same path that these Chinese predecessors have taken.
And he also knows in his heart that once his idea succeeds, the pattern of encoders in the world will change.
Because the dichotomy method obviously can not only be divided once, it can also be divided into four, eight, or even sixteen points.
By then, even if the Huaguo encoder can only reach 1,000 pulses per millimeter, it means that the resolution can only reach 250 nanometers. However, after its structural optimization, it can also be reduced to about 10 nanometers, and then the resolution can be reduced to about 10 nanometers.
The combination of multiple encoders can also be accurate to a lower level.
In this way, after analyzing the structure in front of him, Lin Xiao also took a draft paper in his hand and drew a working drawing on it.
From time to time he stopped to think, and just like that, more ideas emerged in his mind.
"It seems...that's possible?"
Suddenly a flash of inspiration flashed in his mind, Lin Xiao's eyes lit up, and the drawings on the draft paper became more and more complicated.
…
Time passed quickly.
About a month passed.
In this month, Lin Xiao has been studying the encoder.
Of course, the gains are still huge. At least, he has built a new encoder on the software and achieved eight points of its displacement distance, which means that its accuracy has increased by eight times.
However, after the structure is completed, this thing still needs to be built.
If it cannot be made, its actual effect is uncertain.
Of course, if you want to make something, you also need a variety of materials, especially materials that are more rigid.
The displacement distance is divided into eight parts. If the material is not rigid, elastic deformation will occur, so a material with stronger rigidity is needed.
And he already had this material, it was the material from the encoder in his mind.
This material is very rigid and is very suitable for use in encoders, which is very helpful for error modification.
Of course, this material also needs to be prepared first.
"Then let's go to them first."
I thought of the group of postdocs who were still studying ceramic grinding disc materials. Those postdocs had been conducting research based on Lin Xiao's ideas, and they were getting closer to his goal, but I didn't know if they had succeeded.
Then, he left the computer room and went to the materials laboratory.
Seeing Lin Xiao coming over, these postdocs shouted: "Professor Lin!"
"Um."
Lin Xiao nodded and said, "How is the situation?"
"This furnace may succeed!"
One of them replied.
"Well! We have made many adjustments to the centrifugal speed and tantalum melt adding speed, and it should be successful now."
Another person also responded.
"That's fine, I'll just look forward to it."
Since they all said so, Lin Xiao planned to wait and see if they could get something out.
In addition to this grinding disc material, there is also another silicon powder and sodium hydroxide colloidal polishing liquid. Regarding the polishing liquid, Lin Xiao decided to prepare it later. There is no need to rush now, because this chemical is easier to set up a production line than the material.
, so he planned to wait until later.
In this way, time passed quickly and it was almost ready. Several doctoral students immediately went over, turned off the electric arc furnace, and took out the ceramic pieces fired inside.
After the temperature dropped, a dark gray ceramic piece appeared in front of them. They then placed it on the small polishing machine next to it and began to polish it. After a while, a ceramic piece with a smooth surface, just like those modern ceramic crafts, appeared.
appeared in front of them.
Lin Xiao looked at it and then said: "Let's measure its properties."
"good!"
The postdocs immediately took the grindstone to measure on various instruments.
Among them, the most important thing is that the thermal expansion coefficient must meet their needs.
Therefore, they first took it to the thermal expansion coefficient measuring instrument for testing.
First, the room temperature is 25 degrees Celsius, and then the measuring instrument is used to slowly heat it and gradually measure its expansion.
Their measuring instrument can be accurate to 10nm, which means that the number can only be detected after the expansion reaches 10nm.
For ultra-precision polishing discs, due to long-term friction, the working temperature may be hundreds of degrees Celsius, so its expansion coefficient must be very low.
The results of their previous experiments were not ideal. The thermal expansion coefficient of silicon carbide ceramics was originally between 1.2 and 4.3, and their experimental results were only slightly lower than this range.
This is obviously not enough. It needs to be lower, at least lower than 0.5, to prove that they have succeeded.
Ever since, everyone stared closely at the display on the computer, waiting for its change.
During the continuous heating, the temperature of the tantalum-doped silicon carbide ceramic piece also gradually increased, from 25 degrees Celsius to 125 degrees Celsius.
However, the indication still hasn’t changed!
This shows that the degree of expansion is still less than 10nm!
Seeing this, they immediately clenched their fists and became more and more excited.
Finally, after the temperature reached over 200 degrees Celsius, the indicator finally jumped and it finally expanded by 10nm!
Suddenly, they could no longer contain the excitement in their hearts.
This result is much better than their previous results!
"Li Wei, go and calculate what the coefficient of thermal expansion is!"
Someone immediately shouted that based on the initial thickness and initial temperature of the ceramic piece, they could calculate the final result.
With such a low amount of expansion, the expansion coefficient must be lower than 1!
But how much exactly is it, they also really want to know.
But at this moment, Lin Xiao said directly: "No need to forget it, the expansion coefficient is 0.16."
These doctoral students were stunned, 0.16?
Professor Lin calculated this directly mentally?
And Li Wei was delayed for a few seconds before saying: "It is indeed 0.16!"
Suddenly, they all cast admiring glances at Lin Xiao. Good guy, with this mental arithmetic speed, the most powerful brain can only reach this level, right?
One is nanometers, the other is centimeters, and there is a difference of 10 million.
Of course, Lin Xiao didn't have any feelings about his calculation speed. It was just a basic operation. This result was what he was really happy about.
0.16, basically reaching the value given by the system.
With such a low expansion coefficient, he can now officially announce that China will have its own top-grade polishing disc, breaking the foreign monopoly!
In a few days, he called over the academicians who were studying polishing technology in China and used this new material to explain to them what surprise meant.
Thinking of this, he smiled again, and then looked at the doctoral students in front of him again, only to see them all looking at him.
He couldn't help being stunned, and asked with a smile: "What are you looking at me for? Why don't you celebrate now?"
Hearing what Lin Xiao said, these postdocs also reacted.
Silicon carbide ceramic material with a thermal expansion coefficient of 0.16!
This is obviously the most suitable material for silicon wafer grinding discs, which means that their results have filled a gap for China.
This is obviously a huge achievement for doctoral students like them.
Although all the steps of the research were explained by Lin Xiao, they just followed the methods specified by Lin Xiao. However, since they are participants, they can certainly share a certain amount of honor.
At this time, they looked at Lin Xiao with eyes full of gratitude, and at the same time they were secretly glad that they had not really left in the first place, otherwise they would have lost a lot of money.