Nowadays, it is actually easier to build an electric car, and we can see many cross-border players entering this field, in fact, the threshold is rapidly declining. Since there is no need for complex equipment such as engines and gearboxes, the three-electric system such as motors, electronic controls, and batteries is simple and standard.
Electric vehicles are revolutionizing manufacturing. It is easier to standardize than fuel vehicles, the middle of the chassis of the vehicle is a large battery pack, both ends are motors, if it is not for safety and aesthetic considerations, the entire front of the electric vehicle can not be avoided, the original place where the engine is placed is now a storage box.
Since there are far fewer power components than fuel vehicles, the universal version of the entire chassis is greatly enhanced. For the lower body of the car, if all the motors, drive systems and battery packs can be embedded in the chassis to achieve the "separation" of the entire car's upper and lower car bodies (the professional word is decoupling), then the upper and lower bodies of the car can be independently developed, and the manufacturing of the entire car will become very standardized and modular.
For the upper body of the car, it is also setting off a revolution in the integrated die-casting process. Under the wave of "one-piece die casting" led by Tesla, the large die casting machine in Tesla factory can reduce the casting parts of Model Y from the original 70 to 2, which not only greatly simplifies the production process, but also reduces production time and reduces overall costs.
Will the production of electric vehicles in the future be as standardized as today's smartphones? What mobile phone brand companies need to do is design, and other components can be purchased from outside the module, such as camera module, fingerprint recognition module, processor CPU module, etc., highly integrated.
We are optimistic about the potential and prospects of the skateboard chassis, and we have also invested in the leading yo-running technology in China. Now, we divide the car into the upper body and the lower body to analyze what kind of production revolution the electric car is bringing. Enjoy the following:
General Motors' Autonomy concept car, the industry's earliest design of the upper and lower body separation
1
Electric car lower body: skateboard chassis
The reason why the production and manufacture of electric vehicles is more and more like smart phones, a core change is the chassis.
Electric vehicles can even be said to be built on a "huge skateboard electronics", when the future motor and battery are embedded in the skateboard chassis, the electric vehicle can be designed into any imaginary look, the whimsical cockpit design or appearance, can be arranged on this universal skateboard chassis.
The traditional fuel vehicle is also built on the chassis, but this chassis is not so self-contained, complex components such as engines and steering systems are on it, as well as complex axles, suspension systems, cooling systems, tubing, etc., winding on the chassis. All of this adds up to nearly 30,000 parts, which are screwed, pressed, glued, and welded together. From the very first moment the car comes out of the assembly line, it's hard to change anything.
There are two main ways to design the chassis of electric vehicles, one is to follow the chassis of traditional fuel vehicles, and carry out part of the restructuring work as needed, with little difficulty and low cost, and to a large extent, the mature parts of traditional vehicles are used. However, this method is actually more restricted in the development and design, the optimization of the overall layout is more difficult, and it is difficult to integrate the various electric modules, which can only be used together.
The other is a pure electric platform specially developed for electric vehicles, there is no previous design restrictions, the integration of the exclusive chassis of electric vehicles is higher, the performance is more excellent, and only a few core car companies in the world may have the ability to develop, representing Tesla, Toyota, Volkswagen and so on.
Nowadays, there is another new force emerging, that is, the skateboard chassis platform represented by Rivian and Yo-Yo- Running, whose core concept is to separate and decouple the development of the upper body and the chassis.
This means that when developing the chassis, as long as the interface is defined, it can not care about how the upper body is designed, and then just "splicing" in the future, which is the biggest difference with the pure electric platform.
Two models released by Rivian
Rivian, which went public last November, is a representative of this. Rivian embeds four electric motors, an all-wheel drive system and three battery packs into the chassis to decouple the upper and lower car bodies, enabling them to be developed independently. This skateboard chassis can be adapted to a variety of different models, accelerate the research and development cycle of vehicles, and can be used in addition to private label models, but also open to the public.
Rivian's skateboard chassis is a non-carrier body structure, making it fundamentally different in body structure. This kind of vehicle has a rigid frame, which carries the entire body by the frame, and the suspension and body are installed on the frame, so that the complete chassis can be driven independently, without relying on the body and other superstructures, and the entire body can be more freely space planned.
Rivian's two currently released models, because the battery, motor, electronic control, steering mechanism have been integrated into the chassis, the two cars share as much as 91% of the components, just by assembling different upper bodies to design these two cars.
Because the body does not have to accommodate the chassis at all, the interior space of the car can be maximized, and the R1T even designed a left-right connecting "drawer" in front of the cargo bucket, which can be used for skis, fishing rods or as a camping kitchen.
At the same time as the rise of Rivian, the skateboard chassis quickly became a trend, Canoo, REE and other companies have announced the development of skateboard chassis, Jingwei is very optimistic about the huge potential of skateboard chassis, invested in the domestic leading startup company Yo-Run Technology.
Li Peng, founder of Yo-Run Technology, once said: "The skateboard chassis has a clear judgment line in technology, that is, it does not support the development of upper and lower splits. ”
The chassis of the future, in the understanding of yo-yo running, is the hardware to do subtraction, the function to do addition. The horizontal and vertical directions of the chassis include vertical orientation, the control needs of each item are becoming more and more precise, more and more intelligent, the entire integrated control and the ability to provide are becoming more, and the chassis is gradually becoming a standardized product.
The radical Canopy, designed with the sci-fi Lifes tyleVehicle, is like a moving glass house, with all the space above the chassis available
Decoupling on and off the bus is fatal to freight traffic.
Delivery giants like Amazon, interested in a fleet of deliveries based on skateboard chassis, claimed to have secured 100,000 orders for Amazon's custom vans. For Amazon, these vehicles need to be simple to repair and the parts to be interoperable.
Imagine how long it takes to repair a car like this when it breaks down? You just have to put the car on the jack and pull the upper body off the chassis, a bit like changing spare tires, and then linking it to a new skateboard chassis. It looks like the whole car remains the same, but the powertrain will be new and the whole process will only take a few minutes.
So, what is the difficulty of this up-and-down split body?
The core underlying change lies in the wire control chassis. Many of the design limitations of the traditional chassis are derived from mechanical steering, and most vehicles have a core device - the steering column, which allows the driver to drive the wheel to steer by turning the steering wheel.
However, in the skateboard chassis, the full-line control chassis is adopted. Steer-by-wire, for example, is equivalent to the complete elimination of the mechanical device and the realization of steering only through electronic control. When the driver turns the steering wheel, an electrical signal is input, which is then transmitted to the steering device. Without mechanical control, it is possible to decouple the upper and lower car bodies, as well as the modularity and compactness of the skateboard chassis.
Therefore, another major advantage of the skateboard chassis lies in the combination of software and hardware. Li Peng once summarized the four major technologies of the Yo-Yo-Run UP super chassis: full-wire control chassis, pluggable ring network electronic architecture, CTC battery system and highly integrated thermal management system. On the basis of hardware standardization, the UP super chassis has made some hardware interface standardization design, and also made the software part a platform, so that the software and hardware are also decoupled and can be developed separately.
The computing power can be expanded, just like the external memory stick to the computer, the computing power can be expanded at any time, and enough computing power space is reserved for the future L4 and above automatic driving, because the "basic disk" of the future intelligent electric vehicle may be - more than 1000 kilometers, and the computing power is more than 1000 TOPS.
Based on the same skateboard chassis, different upper bodies can be linked. Image source: Yo-Run Technology
Li Peng believes that the pain point of the existing car-making model is that the integrated development of the whole vehicle has brought about the problems of long cycle, large investment and slow iteration, which has a huge tear with the increasingly personalized user needs. The solution proposed by Yo-Pao is to start from the standardization of the chassis and open up more personalized imagination space on the car body.
The full-line control of the skateboard chassis, free up the space inside the car, provides a very free stage for vehicle designers, with the ultimate standardization, the ultimate personalization, but also greatly reduces the threshold of car manufacturing.
The production and manufacture of electric vehicles in the future is likely to be as standardized and modular as smartphones. Ouyang Minggao, an academician of the Chinese Academy of Sciences, once proposed: In the future trend of electric vehicle technology, everyone cares about two things, one is a thousand kilometer endurance, and the other is a skateboard chassis. The skateboard chassis will undoubtedly bring a revolution to the design and manufacture of electric vehicles.
2
Electric vehicle upper body: integrated casting
As early as 2020 Tesla Battery Day, Musk introduced the rear body structural parts of the Model Y model, which will use a new one-piece die-casting process. Compared with the traditional stamping-welding process, this technology has reduced the number of cast parts from 70 to 2, greatly simplifying the production process, reducing production time and reducing costs by 40%.
It can be seen from the development of Tesla body integration that Tesla's goal is to directly assemble several body structural parts that are integrated and die-cast like building blocks. At present, there is no integrated die casting of the whole vehicle level, and Tesla has integrated the second half of the body.
The Model Y components that Musk showed off at Battery Day 2020
Tesla's first phase, the Model S and Model X stages, used an all-aluminum body, but still developed the vehicle according to the traditional stamping-welding process route.
In the second phase, Tesla used a 6,000-ton integrated die-casting machine for the first time when producing the Model Y. This has reduced the number of parts for the Model Y by 79 compared to the Model 3, from approximately 700-800 to 50 solder joints, reduced the weight of the assembly of the car body by 30%, reduced manufacturing costs by 40%, and reduced the manufacturing time from 1-2 hours to 3-5 minutes in the traditional process.
In Tesla's four major global super factories, more than 6,000 tons of die casting machines have been deployed, including 2 in the Fremont factory, 3 in the Shanghai factory, 8 in the Berlin factory, and 4 in the Austin factory.
At the end of 2020, in the die-casting workshop of Tesla's Shanghai Gigafactory, three sets (sets) of giant die-casting machines (islands) with a clamping force of 6000T were successfully put into production, mainly producing model Y models with one-piece molded auto parts on the back plate
At the Berlin factory open house in 2021, Tesla demonstrated the integrated die-casting chassis, which plans to replace the entire assembly of the car body composed of 370 parts with 2-3 large die-casting parts, which will further reduce the weight by 10% and increase the corresponding cruising range by 14%.
In the third stage of the future, Tesla will go further and realize the integration of the front body, the integration of the rear body, and the integration of the chassis battery pack, and truly realize the "building block" production.
In the traditional automobile production, the main stamping welding process is divided into four links: stamping, welding, painting and assembly. In the first stamping link, the stamping workshop uses different presses to complete the manufacture of doors, left and right side walls, cabin covers, front and rear bottom plates, top covers, back doors and various stamping small parts. Then the second step is welding, where the welding workshop is responsible for welding together the stamped body wraps to complete the manufacture of the body-in-white.
The third step is painting, also known as the paint workshop, attaching various anti-corrosion processes to the white body, and spraying with beautiful color paint and varnish to achieve the role of coloring and surface protection. The final fourth step is final assembly, which assembles various parts and systems on the body into a complete car, and conducts a series of tests such as spot inspection and road test, and finally goes offline to become a qualified commercial vehicle.
Tesla in the Model Y manufacturing revolution, directly integrated die-casting the entire rear back plate of the body, including the left and right side of the vehicle rear wheel cover inner plate, rear longitudinal beam, bottom plate connection plate, beam reinforcement plate and other parts, only as we said earlier "the number of parts reduced from 79 to 2, welding joints from 700-800 to 50", Model Y's white body rear, almost no welding traces visible to the naked eye, greatly improving the stability of the body structure.
At the same time, because the production of parts requires a variety of molds, robotic arms, fixtures, assembly parts also need different production lines, so a large reduction of parts, it significantly reduces the cost of molds and assembly costs. Although a die casting machine is large, it is still much smaller than the traditional production line, covering an area of only 100 square meters.
Musk has said that after the adoption of large die casting machines, the footprint of Tesla's factory has been reduced by 30%, and infrastructure costs have been greatly reduced.
In addition to the small footprint, the production speed of integrated die casting technology is also much faster. Large-scale integrated die casting machines take only 80-90 seconds to die casting at a time and can produce 1,000 castings a day, while traditional processes require at least two hours to stamp and weld a part. Due to the application of new alloy materials, the surface of the die casting is smooth enough, basically no longer need to be machined, the previous average welding workshop needed to be equipped with 200-300 production line workers, integrated die casting technology because of the simplification of the production process, the manpower required can be reduced to one-tenth of the original.
Tesla Giga Press die-cast integrated parts
However, it is not an easy task to achieve integrated die casting. Because the changes in its profile, cross-section, and material thickness are very drastic, compared with the single die-casting structural parts mass-produced by traditional car companies, it is not just as simple as using a larger die-casting machine, but also requires systematic innovation.
This technical barrier is mainly reflected in three aspects, namely material, mold, die casting process control.
The first difficulty is the material. There was a news in 2015 that Tesla had hired charles Kuehmann, an aluminum alloy expert from Apple, who was mainly responsible for the materials engineering of Space X and Tesla. At that time, Tesla wanted to develop a new aluminum alloy material.
Integrated castings require material innovation and the development of special heat-free aluminum alloys.
Why use aluminum in the first place? Because aluminum is very light, and the strength and toughness are enough, electric vehicles are very sensitive to weight based on the requirements of increasing endurance. The weight of the integrated all-aluminum die-cast in-white body is 200-250kg, while the weight of the steel body of the same class is 350-450kg. For example, the model Y's one-piece die-cast body weighs only 66 kg, which is 10-20 kg lighter than the same part of the smaller Model 3, which increases the endurance.
In the traditional aluminum die-casting body parts, in order to meet the high elongation to ensure riveting performance, it is usually necessary to carry out solid solution + aging heat treatment, but the integrated casting size is larger, and it is easy to issue deformation for heat treatment, so special heat-free aluminum alloy is required, that is, the mechanical properties of the product can be guaranteed while not heat treatment.
This requires this new material to meet a bunch of conditions: 1, there is a good rheological performance of the plastic body, that is, under the action of pressure, the aluminum alloy still has good fluidity, easy to fill complex structures, reduce the gradual internal shrinkage cavity; 2, the line shrinkage rate is smaller, and there is a certain high temperature strength, so as to avoid cracks and deformation of the casting, improve the size accuracy of the casting; 3, the crystallization temperature range is small, can reduce the possibility of shrinkage holes in the casting; 4, with better high temperature solid strength, Prevent deformation or rupture of castings when the mold is opened; 5, at room temperature should have a certain strength, improve the mechanical strength and surface hardness of the die casting; 6, there is no chemical reaction with the die casting type, the affinity is small, to prevent the viscosity and casting, the mold mutual alloying; 7, in the high temperature melting state is not easy to inhale, oxidation, in order to meet the requirements of long-term heat preservation when die casting.
Doesn't it look like it's not easy to develop? So first in the material side, for example, Tesla chose to develop itself, which is the exclusive secret of various aluminum companies or car brands.
In recent years, different enterprises in the mainland are also developing new materials, die-casting aluminum alloys such as EZCastTM alloy, Aural-2, Aural-4, A365 and Mercalloy are currently widely used in body structural parts to reduce the weight of automobiles.
The second technical difficulty is the mold.
The clamping force of integrated die casting is stronger, and the residual stress can cause damage to the mold. In the die casting process, the mold has been pulled by various forces, and the working conditions are very harsh.
When the molten metal enters the mold cavity in the early stage, the space in the cavity is limited, and a tensile force is generated at the concave corner of the cavity. When the mold temperature is gradually increased by the influence of the temperature of the molten metal, the mold is heated and expanded, and the pressure stress is generated on the mold surface. After the late casting is released, the mold is cold treated, the mold shrinks, and the tangential tensile stress is generated.
In each link, the mold due to various pressures, may lead to cracks, while the release agent or other impurities attached to the mold will produce carbon deposition, affecting the yield rate of subsequent products, but also affect the service life of the mold, and the service life is directly related to the comprehensive cost.
In addition to being resistant, the design of the mold itself is also more complex and requires great precision. If the design of the casting slope value is unreasonable, it will cause core extraction, which is easy to cause abrasion when picking up the part after opening the mold, and the degree of smoothness at the corner will lead to the occurrence of stomata. Die castings will also produce pores due to poor exhaust, shrinkage holes in aluminum alloys, and excessive wall thickness differences in products. Poor design can lead to uneven casting wall thicknesses, leading to cracks.
The third challenge is the control of the die casting process.
Throughout the die casting operation, there are dozens of parameters, involving heating temperature, mold temperature, the use of mold release agents and many other links, each process is closely related to product performance and yield. Due to the large body parts of the integrated car, the longer the aluminum filling mold time, the longer the time, the more difficult the control in the die casting process.
For example, the driving ability of large die casting machines, the more complex the structure of die casting, the higher the requirements for structural parameters such as draft angle, insertion angle, exhaust hole, mold outlet mode, shrinkage direction and so on. The stricter the control of process parameters such as liquid metal filling cavity speed, flow state, injection specific pressure, and injection speed.
There are also examples such as mold temperature control, analysis of the thermal balance of the mold, reasonable design of cooling / heating pipes, is the precondition for effective control of the mold temperature in production, the surface temperature control of the mold has a great impact on the integrated die casting, such as the low temperature of the front section of the molten soup, the die casting will produce cold grain.
In summary, in fact, integrated die casting is not easy, and it requires breakthroughs in various technical links. But for electric vehicle companies, this is another very important trend.
In addition to the advantages mentioned earlier, one-piece die casting has two more lethal advantages - faster pace of research and development and higher precision of car construction.
Compared with traditional fuel vehicles, electric vehicles have a much shorter cycle of update iteration, automatic driving, intelligent cockpit and other functions are constantly innovating, once there is a burst of products that need to be quickly produced to the market, and integrated die-casting technology can shorten the model development cycle by two-thirds because it simplifies a large number of processes.
On the other hand, due to the integrated die-casting technology to improve the accuracy level of the car to the micron level, in the field of automatic driving, the vehicle needs to detect and perceive the road conditions through high-precision measurement equipment such as lidar, millimeter wave radar, and high-definition cameras, which have extremely stringent requirements for the installation accuracy of the yaw angle, pitch angle and rolling angle.
The precision of the traditional body manufacturing process is actually more difficult to meet the installation needs of high-stage automatic driving equipment. The one-piece die-casting replaces multiple body enclosures stamped and welded with integral parts, which can effectively avoid the accumulation of errors in the welding of a large number of parts. Die-cast parts shorten the body matching size chain to two to three rings, the fewer the size chain links, the less factors affecting the accuracy of the body, and the better the realization and stability of the body accuracy. Coupled with CNC machining technology, it is even possible to improve the accuracy of the whole vehicle to the micron level.
At present, many electric vehicle companies, die casting machine equipment factories, and aluminum die casting enterprises are vigorously laying out integrated die casting. In addition to Tesla, Ideal, Xiaopeng, Weilai, Huawei/Cilis, and Xiaomi are all laying out integrated die-casting, which is an obvious trend in the production of electric vehicles.
Comparison of the integrated die-casting model with the traditional "stamping + welding" model in the supply chain; data source: Everbright Securities
The skateboard chassis and integrated casting, corresponding to the lower and upper body of the car, are all manufacturing revolutions that are taking place.
Since electric vehicles have far fewer moving parts than fuel vehicles, the performance of battery packs and motors is very transparent and versatile, and future electric vehicle brands can even buy these skateboard chassis from third parties, just like Dell or Lenovo purchased processors from Intel, and future electric vehicles need different product definitions and designs.
These modular components bring a blank canvas to car companies, any shape, any size, any function can be possible, to break through the boundaries and create a different next generation of electric vehicles.
In the future, one of Jobs's ideas for creating the iPhone could be rife again — I'm going to tell consumers what they want, and when they see the product, they'll love it.
In the future, power will no longer be the battlefield for electric vehicle companies, and the new battlefield will be design and product definition
References:
Barclays：Rivian EVs for Amazon and Adventure
Morgan Stanley：Rivian The One
Tianfeng Securities: 4680 battery cell, CTC technology and integrated die casting technology
Orient Securities: Automotive lightweight and integrated die casting industry analysis
Guosen Securities: From the perspective of Model_Y, aluminum die casting has developed towards large-scale and integration
Huaxi Securities: Less+is+More, accelerated car lightweighting
Soochow Securities: integrated die casting, cost reduction and efficiency increase + precision controllable, a new revolution in body manufacturing
Zheshang Securities: The wave of body integration has been set off, casting aluminum die-casting tomorrow's stars