Zhong Shihong, who was still smiling just now, froze in place with a strange expression.

The other people who came with him also showed all kinds of surprised expressions.

Chang Haonan was the only one in the audience who was not particularly surprised.

It was similar to what he had expected.

Electro-hydraulic beam machining is an electrochemical processing method, which in principle does not produce microcracks and remelting layers in the formed pore structure, and the main problem is that the local edge quality is not stable enough, so the detection of suitable processing methods will focus on the area around the orifice.

Whereas EDM is still hot in nature, recasting inevitably occurs during the perforation process.

Although the high-pressure internal flush inside the hollow electrode can quickly wash away some of the molten material during processing, the remaining part may still produce a remelt layer with a very irregular thickness after cooling, which will affect the product quality.

Problems arise when the processing method is changed without corresponding improvements to the inspection process.

It's just that in actual operation, the relationship between the thickness of the remelted layer and the processing current, pulse width and environmental parameters is very close, so Chang Haonan didn't dare to insist that this was the result when he didn't see the test results before.

But now it can.

"There is no problem with the cost, and we hope to get the test results as soon as possible."

Zhou Zexuan nodded, and took out two turbine blade samples from the optical testing table next to him:

"The Electron Microscope Center has an ongoing mission right now, but your situation is special after all, and I can apply to join the queue."

After that, he turned and left.

With Zhou Zexuan's operation, everyone didn't wait too long to get the results of the electron microscope test.

"We randomly selected 16 pores on the blade for testing, and the results showed that the average thickness of the remelting layer in the holes was 25 microns, but the condition of each hole varied greatly, from the thinnest to 14 microns and the thickest 45 microns......"

As Zhou Zexuan read out the results on the test report little by little, Zhong Shihong's face became darker and darker.

He's not a face-saving person, but this slap in the face came too quickly......

After all, a few days ago, he swore that there would definitely be no problems in EDM drilling technology in Factory 410.

Chang Haonan's performance was as normal as ever, he took the report from Zhou Zexuan's hand and looked at it, and after making sure that there were no other noteworthy problems, he handed it to others.

The air in the room became a little scorching.

"This ......"

Although he is very reluctant to admit it, it is indeed the same as Chang Haonan's initial guess, there is a loophole in the post-processing and quality inspection process.

And what made Zhong Shihong even more ashamed was that the 410 factory had received a letter from Yan Zhongzhong and others from Fucheng before, requesting a self-inspection of the production process of engine hot-end components.

However, they just re-sampled the samples according to the usual inspection process, and after finding that there were no problems, they restarted production.

Therefore, the quality problem of the inner wall processing of the small hole is missed.

The evidence is in front of you, and since there is a mistake, you have to admit it.

"After we go back, we will hold a factory-wide staff meeting, and we need to review this matter."

……

However, the 611 side is in a hurry for the turbojet 14B.

After all, it involves the work of Feifa matching, and there are also foreign users who have already expressed their purchase intentions to put pressure.

Therefore, before the review, the problem must be solved first.

Back in the evening of the 410 plant, the first thing that was held was a small-scale technical seminar.

"With the current situation in China, there is no hope for switching to electro-hydraulic beam processing in the short term, so we have no other choice but to think of a solution on the basis of EDM technology."

Zhong Shihong set the tone at the beginning:

"He Gong, can you consider reducing the thickness of the remelting layer during processing by reducing the current intensity or shortening the pulse width?"

Sitting here are all old technologies, and now that the problem has been determined to be the occurrence of a remelting layer, some basic principles are still difficult for everyone.

The middle-aged man known as He Gong is called He Tao, who is the section leader responsible for the EDM drilling process.

Unfortunately, there is still a gap between the basic principle and the actual operation.

He Tao shook his head decisively:

"The material processing of turbine blades is already difficult, although reducing the current intensity can alleviate the problem of remelting, but it will affect the accuracy and position of the opening, and now the current of 8 amperes is already the minimum current that can maintain the processing quality after testing in our section."

"As for shortening the pulse width, that's not something we can control, we need to replace better and more precise electrodes, and the clamping equipment needs to be replaced......"

He didn't go on, but the conclusion was already very obvious.

Nowadays, this EDM small hole machining machine tool is something that has been taken out after several years of research in the 410 factory, where to find more advanced equipment?

The manufacturing industry is sometimes like this, it takes a long time to break through if you want to implement it on the production side.

"Since there is no way to reduce the thickness of the remelted layer during processing, we have to consider the post-processing process."

Zhong Shihong looked at the other engineer.

The other man coughed lightly twice, and then said:

"I just looked at the results of the electron microscope, the current 0.2mm reamer can only remove the burrs and residues on the inner wall of the small hole, judging from the metallographic structure of the remelted layer, its hardness is very high, and there is no way to completely remove it by mechanical reaming."

"In addition, the turbine blade itself is a thin-walled part with high requirements for deformation, the mechanical reaming process is very difficult and the efficiency is very low, there are hundreds of phosgene film holes on each product, if you do each small hole again, I am afraid that there are no 100-200 man-hours can not be used at all, and an engine will probably have to be used...... Two months. ”

The discussion stalled for a while.

Deep hole processing is a difficult problem in the mechanical manufacturing process, and turbine blades due to their special working environment, the requirements for production and manufacturing are more demanding, the number of air film holes is large and the diameter is small, and many commonly used polishing methods can not be used.

In fact, with the technical strength of the 410 factory, it is not even possible to test the thickness of the remelted layer.

This is also an objective factor that they have not found out about this problem before.

Chang Haonan, who had been sitting next to Zhong Shihong since the beginning of the meeting, did not speak.

In the notebook in front of him, he listed several of the main problems of the moment.

The first is that there must be something hard enough to remove the remelt layer, and according to the results of the discussion just now, steel reamers do not meet this requirement.

The second is that this process must not cause damage to the blade itself, and the clamping process should be simple enough.

Finally, the processing efficiency is high enough, and it is better to be able to process hundreds of air film holes on one blade at the same time, rather than one by one.

……

Chang Haonan, who couldn't figure out his thoughts for a while, almost unconsciously picked up the cup in front of him and took a big sip of water.

The fried meat with granulation for dinner is a bit stuffy......

And at this moment, a spiritual light suddenly flashed through his mind.

Seem...... The process is similar to gargling, or scaling?

Is that something to consider......

No, why not consider using a fluid doped with a high hardness abrasive to remove the remelt layer?

I can't contact the editor, 174 Let's talk about it, the general content is that the existence of the remelt layer was discovered through testing, and by the way, the protagonist brainstormed the layout of the production of large aircraft

(End of chapter)