Chapter 103 Creating Difficulties (Added update for monthly ticket financier flankerr

Following the direction pointed by Chang Haonan, Zhong Shihong quickly saw the leaves piled in the corner:

"Oh, those are basically waste products that have been damaged or failed to pass the test and are judged to be unusable."

"Scrap?"

Chang Haonan was stunned:

"So many?"

Although it was far away, he could still vaguely see clearly that there were at least hundreds of leaves there.

For a factory with full production capacity, this quantity may not be much, but in recent years, the army's order quantity has been insufficient, and production has to be divided between Zhucheng and Shengjing, so a large part of the 410 factory's production capacity is at in idle state.

After this calculation, the yield rate seems not optimistic.

Is it said that the production of compressor blades is not difficult?

"Well...it's actually not much. These are the amounts accumulated in the past six months, and they also include Turbojet 13 and Turbojet 7. They are all piled up there."

While explaining, Zhong Shihong took Chang Haonan directly over, and then picked up a leaf from the ground:

"Originally, these things should be disposed of regularly, but one of our engineers has recently been studying the use of surfacing technology to repair these damaged scraps, so we left some of them for him."

"Are these just part of it?"

The latter was a little dumbfounded by the spectacular sight in front of him, and after a while he asked:

"Then what is our overall yield rate?"

"Is this...the passing rate of a three-dimensional coordinate inspection is about 60%, but the remaining 40% can still be saved. Overall, it can reach about 80%, and in good times it can reach 85%."

As the director of the Technology Department, Zhong Shihong naturally knew these data very well. He reported the answer almost without thinking, and at the same time handed the blade he just picked up to Chang Haonan.

"So high? Then these..."

The latter turned it over and looked at the waste product in his hand, but it was really difficult to see what was wrong with the naked eye.

"The yield rate only considers the processing process." Zhong Shihong fixed the hat on his head for a moment: "Most of the blades here are damaged during assembly and testing."

“At present, most compressor blade materials are only martensitic stainless steel, and at most low-grade ordinary titanium materials such as Ti-6Al-4V are used. We are familiar with the milling of these materials, and at most add a few stresses. The release process only affects some production efficiency."

"But you know, our country's aero engines borrow a lot from Soviet design, so some riveting structures are used in the assembly process of blades, discs and casings. The material of these aviation fasteners is generally Soviet grade 6t16 titanium alloy. That is, Ti-3Al-5Mo-4.5V, which is relatively new to us, and is prone to problems whether in production, processing or assembly."

"So that's it..." Chang Haonan understood in his heart and secretly wrote down what Zhong Shihong said.

China’s research on titanium alloy materials itself is not too late. Titanium alloys such as TB2 and TC4, which are used in large quantities in the aviation field, were basically domestically produced in the 60s and 70s.

Including the 6t16 just mentioned by Zhong Shihong, its domestic model TC16 titanium alloy was also born around 1990.

But the problem is that just a piece of material is useless.

Producing titanium alloy bars is only the first step in a long journey of thousands of miles.

And to take a step back, even for the latest brands of products such as the United States' Ti1100 and Russia's 6t36, the blanks themselves do not restrict exports. As long as they are willing to spend money, they are not difficult to buy in most countries (such as India).

However, each different material, due to its different physical and chemical properties, requires corresponding treatment and processing technology before it can truly become a usable product.

These processes are almost impossible to obtain through imitation, and they are also the real technical barriers.

Obviously, 410 Factory is stuck in these two links.

Subsequently, Chang Haonan visited several other technological processes under the leadership of Zhong Shihong, but he was always thinking about the pile of waste products just now.

Finally, when he saw the riveting and assembly process mentioned before, he couldn't help but ask:

"Speaking of which, since our compressor is already a completely new design, shouldn't we consider abandoning the riveted structure and completely switching to mortise and tenon joints? Moreover, it can also reduce the work of the compressor by forming a transition fit or a small gap fit between the tenon and the tenon groove. The vibrations of time are also higher.”

Although it was Chang Haonan's first time to watch the production process of an aero-engine live, he knew very well with the knowledge and experience of later generations that even in Soviet-made engines, the use of rivets as blade fasteners was definitely a gimmick. Coincidentally, this is the engine used in the R7F-11 engine introduced with the J-300.

This question really made Zhong Shihong look at Chang Haonan with admiration.

At least it shows that the latter is not just coming to the factory to show off, but actually has a certain understanding of production and processing.

"Of course we have considered replacing riveting with tenon joints, but the processing of dovetail tenon is very difficult, and the pressure surface tenon as the assembly reference requires broaching, which requires a special combination broach. Due to the ban on sales, currently It is no longer possible to purchase in bulk through formal channels.”

Apparently, when God closes a door, he often seals the windows.

Therefore, for the Chinese military workers who are groping forward in the ups and downs, if they want to find a way out, they have to find a way to lift the roof.

"It's banned..."

Chang Haonan raised his head again and looked around, and found that most of the processing equipment here were imported from Germany or Japan.

Although the famous Paris Coordinating Committee was disbanded in 1994, its list of prohibited items was inherited by the Wassenaar Agreement almost intact, and the embargo pressure faced by China has not diminished.

You know, in Batumi's embargo list, there are nearly 600 more items listed for China alone than for the Soviet Union before the disintegration.

For example, high-precision multi-axis machine tools can be exported to the Soviet Union, but not to China.

"Yes, in fields such as mechanical processing, there is indeed a big gap between us and developed countries." Zhong Shihong's tone was full of helplessness:

"We have also tried to use domestic cutting tools to replace imported ones, but neither the processing accuracy nor the service life can meet the requirements, and they can only be used to process some things that do not require high precision."

Having said this, he turned his head and looked at Chang Haonan next to him, and said half-jokingly: "During this period, I sometimes think, if there is a talent like you in our industry, it will be great." That’s good.”

"Is this..."

Chang Haonan wanted to say that it might not be impossible.

After all, according to the current progress, the development of turbofan 10 will have to be officially put on the agenda as early as next year or the year after next.

By that time, there must be many manufacturing problems that need to be solved by him.

But after thinking about it, I finally didn’t say it.

For one thing, he didn’t know much about the field.

On the other hand, the achievement conversion efficiency in the field of mechanical processing is also relatively low.

Therefore, even with the help of the system, it is difficult to achieve breakthroughs in a short time like fluid dynamics simulation.

In this case, it’s better to let Zhong Shihong emo for a while——

As long as I have no expectations, everything is a surprise.

"Apart from the problem with the blade fastening method, do our factory have any other difficulties in the manufacturing process?"

Chang Haonan's tone seemed to be just asking casually, but in fact he wanted to determine which aspect of knowledge he wanted to learn next.

"If you really want to say it, there are difficulties everywhere. It is difficult to pass every pass, and it is difficult to walk step by step." Zhong Shihong smiled bitterly and shook his head:

"But if I must say it, the current one is the manufacturing and testing of aircraft engine casings. Because it is a large overall thin-walled part, it is very difficult to cast. The current use of no-margin investment casting method has good yield and production efficiency. Very unsatisfactory.”

“The other thing is the turbine blades. Because they are hot-end parts, the material requirements are much higher than those of the compressor. The turbine blades like the turbojet 14 also have air film holes that are required for active cooling, which is also very confusing to process. Headache."

"The third one is..."

Listening to Zhong Shihong's inventory one by one, Chang Haonan felt that his head was a little big...

I'm going to my parents' place for dinner tonight. I'll add a chapter first, and the rest will be added in the next few days (the monthly ticket holder voted 83 times, so 8 chapters will be added)