近日，奧迪(Audi)向外界展示了全新A8車型，包括該車型所采用的14項先進連接工藝，而奧迪主席Rupert Stadler和保時捷董事會主席Oliver Blume也發(fā)表聲明，稱兩家公司也要“連接”起來，不過是從公司戰(zhàn)略層面。
Stadler表示，“我們兩家公司將集結(jié)最優(yōu)秀的人才，聯(lián)手邁向科技的美好未來。”而Blume補充道：“我們將集雙方之所長，強強聯(lián)手，在所有可能有所發(fā)展的領(lǐng)域進行合作。”
這意味著這兩家汽車巨頭將開始共享汽車架構(gòu)、模塊和組件，共同打造面向2025年的交通出行未來，而這一未來的基礎(chǔ)將是電氣化、數(shù)字化和自動駕駛技術(shù)。
盡管如此，兩家公司仍將保持各自品牌的獨立性，并不會失去各自的特質(zhì)。Blume強調(diào)說，“保時捷永遠(yuǎn)都是保時捷。”
據(jù)了解，即將上市的新一代奧迪A8將繼續(xù)沿用全鋁車身的ASF（Audi Space-Frame）技術(shù)。因而Stadler也可以自信的表示，“奧迪也將永遠(yuǎn)是奧迪。”
具體來說，2018款奧迪A8將于今年夏天上市，預(yù)計將采用替代動力系統(tǒng)，并大量添加自動駕駛功能。這輛車的用材將繼續(xù)以鋁材為主，但也將同時采用鋼、鎂等常規(guī)材料。特別指出的是，為了顯著降低重量、增強扭轉(zhuǎn)剛度，新A8還采用了碳纖維增強聚合物(CFRP)的材料。奧迪公司表示，與現(xiàn)行版A8相比，2018款A(yù)8的扭轉(zhuǎn)剛度提升了24%。
目前，奧迪的輕量化設(shè)計中心(Lightweight Design Center)大約有200名專家，其中25位專門研究纖維增強聚合物材料。為了抵消新型安全系統(tǒng)、油電混合動力系統(tǒng)等多種新技術(shù)所帶來的重量增加，奧迪A8的減重之路一直沒有停止。在此背景之下，盡管工程師已經(jīng)竭盡全力，新奧迪A8的重量還是達(dá)到了282公斤（621磅），較上一代的231公斤（509磅）有所增加。
具體來說，A8的后艙壁及連接的置物架采用了CFRP材料，這也是A8車艙中最大的部件之一。奧迪工程師表示，該部件可以為整車提供大約33%的抗扭剛度。
奧迪同時表示，為了更好地吸收縱向和橫向負(fù)載及相應(yīng)的負(fù)載剪力，車輛采用了6到19層碳纖維層疊的設(shè)計，從而提供更好的負(fù)載性能。每層纖維可以以“任何希望的角度”組合在一起，而工程師幾乎不用對這些纖維進行太多處理。
這也就是說，奧迪的這一新工藝可以實現(xiàn)直接使用碳纖維材料進行制造，從而免去了制造碳纖維板的中間步驟。此外，奧迪還將采用另一種新工藝，這個過程需要將纖維層板放在環(huán)氧樹脂中浸潤“幾分鐘”。盡管奧迪A8的車艙仍然采用了熱成型的高強度鋼，但鑄鋁節(jié)點及擠壓型材等也占到了車身材料清單的58%。
工程師表示，新的熱處理鑄鋁合金可以為車身提供超過230 MPa(33,359 psi)的抗拉強度，并在抗拉測試中表現(xiàn)出超過180 MPa(26,107 psi)的抗屈強度。這些合金型材的性能數(shù)據(jù)比之前有“明顯提高”。
工程師表示，奧迪A8懸架支柱托的前支架連接采用了鋁材，從而取得了28%的減重效果。鋁制螺栓可用于將前支架直接固定在懸架支柱托頂部，從而提高抗扭剛度。從安全性能方面來看，在遇到正面碰撞時，車輛前部受到的力可以分散至三個緩沖區(qū)。
此外，奧迪A8的另一個重要變化是采用了14種不同的車身裝配工藝，奧迪表示，在Neckarsulm工廠所生產(chǎn)的新款A(yù)8，所采用的鋁材滾邊技術(shù)、沖壓鉚合及遠(yuǎn)程激光焊接技術(shù)等均為首創(chuàng)。
有意思的是，這款A(yù)8的前、后車門邊框采用了機器人滾壓工藝柔性化包邊技術(shù)，奧迪稱這種設(shè)計可以方便乘客上下車，并優(yōu)化駕駛員在A柱附近的視野。與2017款車型相比，這種車門邊框設(shè)計可以增加36毫米（1.5英寸）的車內(nèi)空間。
沖壓鉚合工藝（Grip punch riveting）可用于固定側(cè)車架，配合機器人滾壓工藝使用，共同為車輛提供結(jié)構(gòu)性焊接支持。
奧迪的先進連接技術(shù)可以將車輛的鋁制側(cè)車架連接至熱成型HSS鋼材的B柱、車頂線及薄型法蘭，這也讓奧迪感到非常驕傲。
值得一提的是，奧迪A8還采用了遠(yuǎn)程激光焊接鋁材。據(jù)悉，通過激光光束的精確定位，焊接邊熱開裂的風(fēng)險會有“相當(dāng)大”的降幅。此外，由于不再需要成本高昂的工藝控制工序，新工藝據(jù)稱還可以在量產(chǎn)時節(jié)省95%的經(jīng)常性生產(chǎn)成本。
目前，2018款奧迪A8的車架正在位于德國Neckasulm的新工廠中生產(chǎn)，該工廠的機器人生產(chǎn)設(shè)備大約有500臺。
As Audi recently revealed details of the structural technology—including 14 advanced joining processes—of its all-new A8, Chairman Rupert Stadler and Porsche Chairman Oliver Blume were also making statements about joining, but on a strategic scale.
“The best brains of both companies will together set the technical course for the future,” said Stadler, and Blume added: “We will utilize the expertise of both companies and take advantage of synergies. We will co-operate wherever it makes sense.”
This means a shared vehicle strategy for architectures, modules and components to shape mobility up to 2025, that will rest on electrification, digitalization and autonomous driving.
But each company will ensure that its respective brands will each retain its individuality. “A Porsche is always a Porsche,” stressed Blume.
And with the upcoming A8, Stadler can rest easy that this Audi will always be an Audi, with its continued use of aluminum and space-frame technology, albeit complemented by other materials.
The model year 2018 car, to be launched this summer and designed to take alternative powertrains and extensive autonomous capability, will be aluminum intensive but will also use steel, magnesium and, significantly for weight saving and torsional rigidity, carbon-fiber reinforced polymer (CFRP). Claimed torsional rigidity is up 24% on the incumbent A8.
Currently, Audi’s Lightweight Design Center employs some 200 specialists, 25 of whom focus on fiber-reinforced polymers, as the battle continues to offset the increased weight of safety systems and expanding specifications plus provision for PHEV technology. Because of this – and despite all the engineers’ best efforts - the new A8’s BIW scales 282 kg (621 lb) against 231 kg (509 lb) for the previous generation.
CFRP is used for the rear panel and associated parcel shelf, the largest component in the occupant cell of the A8. It provides some 33% of the torsional rigidity for the whole car.
Detailing the material, Audi explains that to optimally absorb longitudinal and transverse loads and associated load-shearing forces, between six and 19 fiber layers are placed one above each other to deliver load optimization. The individual fiber layers comprise 50-mm-wide (2-in) tapes placed in a finished layered panel “with any desired fiber angle and minimal trimming of the fibers.”
The process obviates the need for an intermediary step of manufacturing entire sheets of carbon fiber. A further new process sees the layered panel wetted with epoxy resin and cured “within minutes.” Although high strength hot-formed steel components including tailored blanks are used for the occupant cell, aluminum cast nodes, extruded profiles and sheets, account for 58% of the A8’s body.
Detailing the performance of new heat-treated cast alloys, Audi engineers say these attain a tensile strength of more than 230 MPa (33,359 psi); the corresponding yield strength in the tensile test is over 180 MPa (26,107 psi). For the profile alloys, “significantly higher” values are delivered than those previously achieved.
Magnesium is used for a front brace linking the A8’s suspension turrets and provides a 28% weight saving, the engineers claim. Aluminum bolts are used to secure it to the strut tower domes to boost torsional rigidity. In terms of safety performance, a frontal collision would distribute resultant generated forces to three impact buffers in the front end.
A further significant aspect of technologies introduced in the A8’s build is the use of 14 different joining processes in body assembly. These embrace roller hemming, grip punch riveting, and remote laser welding of aluminum “which is being done in Neckarsulm for the first time anywhere in the world,” the company claims.
Interestingly, roller hemming is used round the front and rear door cutouts, described by Audi as aiding passenger accessibility while also improving driver field of view around the A-pillars. Space gain in the cutouts is put at 36 mm (1.5 in) compared to the 2017 car.
The use of grip punch riveting, that fixes the side wall frame in position, accompanies the roller hemming, which is supported by structural bonding.
Audi is particularly proud of its development and adaptation of these joining technologies, combining the aluminum side wall frame with the hot formed HSS sheets at the B-pillar, the roof line and the sills with their thin flanges.
Also significant is remote laser welding of aluminum. Exact positioning of the laser beam in relation to the welding edge is said to “considerably" reduce the risk of hot cracking. The new process is also said to bring a 95% saving on recurring costs in series production, as it eliminates the necessity of expensive process controls.
The car’s spaceframe is being built in a new facility at its Neckarsulm plant. Its robot population is about 500 machines.
Author: Stuart Birch
Source: SAE Automotive Engineering Magazine
全新奧迪A8采用了CFRP材料的后面板和置物板，強度得到了進一步提升。
全新2018款奧迪A8共采用了14項先進連接工藝。
全新奧迪A8采用了鎂材前撐桿。
全新奧迪A8的新一代混合材料車架已經(jīng)成型。
全新奧迪A8的車身結(jié)構(gòu)材料主要以鋁材為主。