Q: How many parts does the driving motor of an electric vehicle have less than that of an internal combustion engine? 100? 300? Or 500? The answer is: 1000+.
According to incomplete statistics, a conventional internal combustion engine generally has more than 1,400 parts; while a drive motor often has only 100 to 200 parts, reducing nearly 1,000 parts.
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For some traditional processing tools, equipment and production lines, these reduced parts are like manual jobs replaced by AI.
The data shows that the market demand for special processing tools for the traditional five major cylinder blocks, cylinder heads, crankshafts, connecting rods, and camshafts is decreasing year by year.
At the same time, however, the metalworking project for electric motors opens up completely new opportunities. For example, metal processing projects such as motor shafts, motor housings, and battery brackets have become new growth points.
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Although different from mechanical transmission, the precision requirements for the processing of new energy vehicle parts have never been lowered. Coupled with the demand for lightweight and special and complex part shapes, it poses more acute challenges to tool and machine tool suppliers.
Large-diameter precision machining of the main hole of the motor housing
The size of the main hole of the motor housing depends on the size of the stator. Since electric vehicles require sufficiently high energy density, the coil diameter on the rotor needs to be within a reasonable range.
Generally, the diameter of the stator of the motor used in electric vehicles is at least φ200mm, which means that the diameter of the main hole of the motor housing must also be above φ200mm.
Pictures of common motor housings
For tool making, φ200mm is already a large diameter tool.
In order to minimize energy loss, the coordination between motor housing/motor shaft/stator and other components must be optimized to the most reasonable range.
Therefore, in the field of machining, the requirements for the machining content of the motor housing, especially the shape and position tolerances of the main hole and the bearing hole are particularly strict. In addition, in order to increase the power density, the motor should be as light and small as possible, which also requires perfect control of the wall thickness of the motor casing.
In summary, high precision, large diameter, thin wall and easy deformation are the main characteristics of motor shell processing at present.
In order to ensure the machining accuracy, the current tool adopts the concept of guide bar tool, and the size can be adjusted in µ level.
The support guide bar plays the role of support, guide and vibration absorption, and the design of the guide bar can offset the deformation in deep hole processing.
More importantly, the weight of the tool is one of the factors that restrict the design of the bar-type tool. If the traditional tool design concept is adopted, the weight of a tool with such a large diameter must be at least 25kg.
In order to adapt to the concept of high-speed machining of modern machine tools, reducing the weight of such tools is a particularly critical technical problem.
With the development of 3D printing technology and metal materials, Kennametal of the United States took the lead in adopting advanced 3D printing and composite material application technology, and took the lead in solving the problem of cutting tool weight reduction.
In addition, it is worth noting that Porsche has previously presented the first electric motor housing completely manufactured using 3D printing and additive manufacturing technology.
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The shell is 3D printed layer by layer with high-quality aluminum alloy powder, combined with laser metal fusion technology.
The final metal 3D printed shell is 10% lighter than traditional castings, and although the thickness is only 1.5mm, its rigidity is stronger than similar parts without honeycomb structure.
Battery pack shell processing
If the motor is like the "legs" of a car, then the battery is the "heart" of the car.
The development trend of power batteries is high density, high capacity, and high voltage, which correspond to the three major terminal requirements of performance, battery life, and fast charging.
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battery pack bracket
This means that in the limited housing space, as many battery modules as possible should be packed, and enough cooling system space should be left inside.
Therefore, the processing trend of the battery pack casing is thinner, more complicated, and lighter.
In order to achieve maximum economy, PCD insert material and oil mist lubrication technology become the key.
According to different machining allowances, machining tasks and parts, it is the core idea to adopt different milling processes to reduce cutting force.
Picture PCD helical edge milling cutter
For example, when machining certain contours, the best way is to use some milling cutters for large stock removal.
In addition to traditional metal processing, automobile lightweight is also the trend of the times. Engineering plastics and various composite materials have become the first choice for lightweight.
For the processing of these parts, we can get inspiration from tool processing in the aerospace field.
For example, using diamond PCD tools can also meet the processing of complex shapes in the face of workpieces such as carbon fiber plates.
