Chapter 1088 Adaptive CNC Machining

However, the relaxed atmosphere did not last long.

A good designer will indeed take into account the difficulties of the production process during the design stage.

But Chang Haonan's processing plan was not much more anthropomorphic than the blade he designed...

He clicked the mouse and turned the PPT to the next page, and said:

"First, a three-layer titanium alloy sheet with a certain shape is processed by milling technology, and a solder stopper is applied to the selected area on the titanium sheet according to the forming requirements of the triangular truss structure..."

"Then, the diffusion bonding process is used to weld the three layers of titanium plates together. The welded blade blank and the fixture are placed in a vacuum furnace and heated to the superplastic state of the titanium alloy, forming a swept blade profile under the action of torque..."

“Then, inert gas is blown between the titanium plates to make the blade blank and the fixture fit perfectly together, forming a triangular truss hollow structure and an aerodynamic shape.”

"Finally, CNC machining is used to process the tenon, blade body, leading and trailing edges, and blade tip. The tenon is usually machined into a formed tenon tooth surface by grinding or milling, the blade body is machined by belt grinding to improve the surface processing quality, and the leading and trailing edges are machined into edge angles by multi-axis milling..."

"..."

At first, no one realized the seriousness of the situation.

But soon, Zhang Zhenhua, who was in charge of process production, began to look unhappy.

As a designer, Chang Haonan naturally couldn't prepare all the process parameters, otherwise the production engineers like them would have no value in existence.

This production route would not be a big problem if it were used on small and medium-sized fans such as the WS-10 or SeA650, with a blade chord length of around 50-60 cm.

However, the fan diameter of AE1500 is nearly two meters, which is almost 56% larger than the CFM7-30 of the same level. The bypass ratio reaches an astonishing 9.03, and the blade chord length also exceeds 90 centimeters. In terms of size alone, it is completely a cross-band product.

For the same processing technology, the difficulty will increase exponentially when the product is doubled in size.

"Mr. Chang..."

After thinking for a moment, Zhang Zhenhua reported his judgment truthfully:

"If it's just samples for production testing, then our equipment has been upgraded and it should be ready soon... before the end of the year at the latest. But if we want to put this process into mass production..."

At this point, he rubbed his hands together nervously.

"I don't dare to give a clear timeline."

Then he took a deep breath and continued as if he had made up his mind:

"The inner shape of the hollow triangular truss structure is formed in one step during the superplastic forming/diffusion bonding process. A small amount of polishing of 0.1-0.15 mm is left at the outer blade body, while the maximum allowance at the tip and root can reach 1.2 mm. The structural characteristics of each processed part require the use of a variety of CNC processing methods, which in turn makes it difficult to smoothly transfer adjacent areas of each processed part."

"In addition, the blade tip, blade root, and leading and trailing edges are solid structures, which are more rigid than the hollow parts of the blade body. Coupled with the alternating solid and virtual triangular hollow truss structure, the entire blade has alternating strong and weak stiffness characteristics, resulting in very complex deformation rules of fan blades during CNC machining, and it is difficult to control the amount of machining deformation using existing means alone."

"Also, during the forming process, titanium alloy sheets have to go through multiple high-temperature and high-pressure cycles. Since it is impossible to control the cooling parameters and wall contact rate 100% accurately, the stress level in different parts of the blade and the strain caused by the stress are also difficult to control."

"If these problems are taken separately, they are not difficult to solve. However, if they are combined and put into large-scale production, it is likely that even the same batch of blade blanks will have poor consistency. It is necessary to take out several processes separately and check the semi-finished products in the production process..."

"..."

Zhang Zhenhua did not continue speaking.

But this is indeed a serious problem.

Industrialized production is actually not afraid of simple complexity.

As long as the equipment and money are in place, and you are willing to spend time, even the most complex process parameters can be gradually determined.

Once the mass production process begins, there will no longer be any cost investment in R&D.

As product output gradually increases, production efficiency and cost can always reach a relatively stable state.

But if the outcome of a certain manufacturing process is uncertain, this means that the subsequent process parameters may have to be determined individually for each individual product.

Although it is much simpler than developing from scratch, it will definitely limit production and costs.

If it is to build rockets or industrial machine tools, the annual output is not that much anyway, so this semi-industrial and semi-handicraft approach is acceptable.

But aircraft engine blades are something that is in huge demand after all, and it is impossible to put in the effort of carving to make them.

For a moment, almost all eyes in the entire conference room were focused on Chang Haonan who was sitting in the front.

"Regarding this question...you should first do it in the sample method. It doesn't matter if the output is small, as long as you can ensure that it can enter the testing phase normally."

He had anticipated the obstacles in the production process as early as when he first conceived the overall design.

Otherwise, it would be impossible to leave such a long execution time for the entire project when the core machine is already available.

"The specific process..."

Zhang Zhenhua said this while glancing at the flow chart on the PPT.

"Let's do as we just said!"

Chang Haonan gave a decisive answer, and then continued:

"I plan to cooperate with the machine tool department to solve the problem of adaptive machining before the mass production of AE1500, which can also be regarded as solving some technical difficulties for our sister units in advance..."

In fact, in the original timeline, the first industry to be troubled by this problem was not the aviation industry, but aerospace and shipbuilding.

China's aerospace industry experienced a dark moment in the mid-to-late 2010s when its launch success rate was even lower than that of neighboring India. This was during the painful period of transition from handicraft to industrial production.

It took many years to finally resolve it.

Now Chang Haonan has set the stage for them.

"Machine tool department?"

Zhang Zhenhua was stunned——

I've never heard that your group has a unit specifically responsible for equipment manufacturing?

"It is the joint venture established by Torch Group and CB Ferrari."

Chang Haonan explained:

"The problem of poor processing consistency cannot be solved by calculations and predictions before production. We can only find a solution during the process of process execution... Comrade Zhenhua just said that the most direct solution is to measure the processing results after each step, and then determine the next process parameters based on the measurement results."

"If this process is carried out separately, it will definitely interrupt the production process. However, if on-machine measurement can be achieved, that is, in the next step, the measurement and processing operations can be completed simultaneously with one clamping, avoiding the impact of repeated disassembly and clamping on the measurement and processing accuracy. Combined with the adaptive CNC technology of overall adaptive deformation of the template tool position and local smooth transition deformation, the continuity of the entire production process can be maintained..."

"..."

In fact, Zhang Zhenhua originally just asked casually about the equipment.

This is not his area of ​​expertise.

However, the idea given by Chang Haonan was indeed a bit outrageous.

Simply put, it does not solve the consistency problem in the production process, but directly ensures the consistency of the final product by using different parameters for different semi-finished products.

It is equivalent to automating the manual work of the master craftsman.

But regardless of whether the adaptive CNC programming technology can truly achieve "teaching students in accordance with their aptitude", the on-machine measurement mentioned above is also difficult to implement.

He asked almost subconsciously:

"But Mr. Chang, due to the limitation of the clamping method and the large bending and twisting degree of the blade, some positioning points on the trailing edge must be manually checked during the measurement process... If we give up this part, the final accuracy will probably be somewhat lower than that of manual intervention..."

This is true.

Even with the development of human industry to this day, the most sophisticated work is still done manually.

Therefore, in traditional processing ideas, precision and production efficiency are almost an irreconcilable contradiction.

But sometimes, you can change your mindset.

From overcoming errors to accepting errors.

However, before Chang Haonan could give any response, Ren Bingda, who had been silent before, raised his head first:

"In fact, when I visited Rolls-Royce before, I found that they did not have such fine requirements for the outer edge of the fan or turbine blades."

"We usually first process the leading and trailing edge angles to suit the size of the blank, then put the processed blades from the same batch together for measurement and weighing, and select the blades with similar shapes, masses and center of mass positions to install on the same turbofan engine, rather than ensuring that all blades are 100% processed in the same way."

"So, according to Mr. Chang's idea, the accuracy of on-machine detection...may be acceptable."