Chapter 1088 Adaptive CNC Machining

However, the relaxed atmosphere did not last long.

A good designer will indeed consider the difficulties of the production process during the design stage.

But the processing plan planned by Chang Haonan is not much more anthropomorphic than the blade itself he designed...

He just clicked the mouse, turned the PPT to the next page, and said at the same time:

"First, a milling process is used to process a three-layer titanium alloy sheet with a certain shape, and the soldering inhibitor is applied to the titanium plate in a selected area according to the forming requirements of the triangular truss structure..."

“Then the diffusion joining process is used to weld the three layers of titanium plates into one piece, and the welded blade blank and the clamp are placed in a vacuum furnace to be heated to the superplastic state of the titanium alloy, and a swept blade shape is formed under the action of torque... "

“Then inert gas is blown between the titanium plates so that the blade blank and the clamp are completely attached, forming a triangular truss hollow structure and aerodynamic shape.”

“Finally, CNC machining is used to process the tenons, blade body, front and rear edges, and blade tips. The tenons are usually processed by grinding or milling to form the tenon tooth surface, and the blade body is grinded with abrasive belts to improve the surface processing quality, and the front and rear edges are Use multi-axis milling to process edges..."

"..."

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

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

As a designer, it is naturally impossible for Chang Haonan to prepare the process parameters, otherwise the production engineers like them would have no value in existence.

If this production route is applied to small and medium-sized fans such as Turbofan 10 or SeA650 with a blade chord length of about 50-60 cm, there will be no big problem.

However, the diameter of the AE1500 fan is nearly two meters, which is almost 30% larger than the CFM56-7 of the same level. The bypass ratio reaches an astonishing 9.03, and the blade chord length also exceeds 90 cm. In terms of size alone, it is completely cross-band. product.

With the same processing technology, after the product is doubled, the difficulty will not be doubled.

"Mr. Chang..."

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

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

Having said this, he rubbed his hands together nervously:

"I dare not give a definite timetable."

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 joining process. A small amount of polishing of 0.1~0.15mm is left in the blade body of the shape, while the highest margins in the blade tip and root parts can Reaching 1.2mm, the structural characteristics of each processing part require the use of diversified CNC processing methods, which in turn makes it difficult to smoothly transfer adjacent areas of each processing part.”

"In addition, the blade tips, blade roots and front and rear edges are solid structures, which are more rigid than the hollow parts of the blade body. Coupled with the triangular hollow truss structure that alternates between virtual and solid, the entire blade has alternating stiffness characteristics, resulting in fan blades The deformation rules during CNC machining are very complex, and it is difficult to control the amount of machining deformation by existing means alone.”

"Also, during the forming process, the titanium alloy sheet has to go through multiple high-temperature and high-pressure cycles. Since it is impossible to control the cooling parameters and wall adhesion rate 100% accurately, the stress levels in different parts of the blade are affected by stress. The resulting strain is also difficult to control.”

“If these problems are taken out individually, they are actually not difficult to solve, but when combined together and put into mass production, it is likely that even the blade blanks of the same batch will have poor consistency, requiring several separate processes. , to check the semi-finished products in the production process..."

"..."

Zhang Zhenhua did not continue.

But this is indeed a serious problem.

Industrial production is actually not afraid of simplicity and complexity.

As long as the equipment and money are in place, and you are willing to spend time, the process parameters, no matter how complex, can be gradually determined.

Once it enters the mass production process, it will no longer involve cost investment at the research and development level.

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

But if the results of a certain processing process cannot be determined, it means that the subsequent process parameters may have to be determined individually for each individual product.

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

If you are building rockets or industrial aircraft, then the annual output is not much anyway, so this semi-industrial and semi-handicraft approach is still acceptable.

But after all, aviation engine blades are in huge demand, and it is impossible to produce them with carving skills.

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

"Regarding this issue...you should do it according to the sample method first. It doesn't matter if the output is small, as long as it can enter the testing process normally."

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

Otherwise, it would be impossible to allow such a long execution time for the entire project on the premise that the core machine is already available.

"The specific process..."

Zhang Zhenhua said and glanced at the flow chart on the PPT.

"I'd better do what I 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. This can be regarded as solving some technical difficulties for our brother units in advance..."

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

In the mid-to-late 2010s, China Aerospace had a dark moment when its launch success rate was even lower than that of India next door. It was going through the painful period of transition from handicraft industry to industry.

In the end it took many years to resolve.

Now Chang Haonan has laid a trap for them.

"Machine tool department?"

Zhang Zhenhua was immediately stunned——

Never heard that your own group has a unit specifically responsible for equipment manufacturing?

"It's a joint venture established by Torch Group and C.B. Ferrari."

Chang Haonan explained:

"The problem of poor processing consistency cannot be solved by calculations and predictions before production alone. We can only find solutions in the process of process execution... Comrade Zhenhua also said just now that the most direct solution is to After a step is completed, the processing results are measured, and the next process parameters are determined based on the measurement results.”

"If this process is carried out alone, 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 with one clamping to avoid repeated disassembly and clamping. The impact of measurement and machining accuracy, combined with the adaptive CNC technology of overall adaptive deformation of template knife points and local smooth transition deformation, can maintain the continuity of the entire production process..."

"..."

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

This is not his area of ​​expertise.

However, the idea given by Chang Haonan was really outrageous.

To put it simply, 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 old master.

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

He asked almost subconsciously:

"But Mr. Chang, due to the limitations of the clamping method and the excessive bending and twisting of the blades during the measurement process, some positioning points on the trailing edge must be manually calibrated... If this part is abandoned, the final accuracy may be different from manual intervention. There will be a certain gap in comparison..."

This is true.

With the development of human industry to this day, the most sophisticated work is actually still done by human hands.

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

But sometimes, you can actually change your mind -

From overcoming errors to accepting errors.

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

"Actually, when I inspected Rolls-Royce before, I found that their requirements for the outer edge of the fan or turbine blades are not that precise."

“Often, the front and rear edge angles are processed to adapt to the size of the blank, and then the processed blades of the same batch are measured and weighed together, and blades with similar shape, quality and center of mass position are screened out and installed on the same vortex. On the fan engine, it is not 100% guaranteed that all blades will be processed exactly the same.”

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