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castings achieve an average of 15% elongation versus 3% elongation in conventional diecast aluminum parts. Traditionally, high pressure vacuum diecasting has been limited to niche vehicles, but its capability to produce parts meeting crush-zone requirements has drawn interest from car manufacturers, particularly after the MMLV program resulted in a vehicle that reduced weight by nearly 25% while still passing critical frontal safety tests. OEM interest in structural die castings for high volume


vehicle segments has led to increased vacuum diecasting capacity in the marketplace. In August, Magna announced plans to build a new aluminum casting facility in Birming- ham, Ala., U.S., at its KAMTEK facility. KAMTEK will produce lightweight structural parts based on customer demand from North American and foreign domestic OEMs. “We are seeing more and more requests from customers to use this technology for high volume vehicle platforms,” Skszek said. The die castings included in the MMLV concept car


are left and right front shock towers, left and right hinge pillars, left and right kick down rails and left and right rear mid-rail castings. According to Magna, the shock tower is the most common


high pressure vacuum diecast body application. It combines a number of steel parts into a single aluminum component that weights 40% less. Te cast aluminum shock tower reduced the weight from 7.5 lbs. for the baseline to 4.6 lbs. Te kick down rail, which is located below the hinge pil-


lar, had the highest performance requirement of the castings. As a chassis reinforcement in the front of the vehicle, it had to show that in a crash, it would not exceed the intrusion specification into the passenger compartment foot well area. Te high pressure vacuum diecasting process allows the casting to be heat treated for stiffness, leading to increased torque load capacity and torsional rigidity to the MMLV body structure. FEA analysis showed the cast kick down rail resulted in better intrusion characteristics in the vehicle compared to the baseline design. Te cast aluminum kick down rail combines five steel stampings lowered the weight from 13 lbs. to 10 lbs. Te hinge pillar casting integrates five steel stampings and is about 35% lighter than the baseline, reducing weight from 9.8 lbs. to 7.4 lbs. Finally, the mid-rail casting design inte- grates 12 rear shock tower and rail components into a single casting for a weight reduction from 12.5 lbs. to 9.2 lbs.


Joining Metals


One of the biggest challenges in designing a multi-material structure is determining the joining methods between parts made in different metals.


在真空环境中生产的铸件,因为铸件中没有气泡或 由气体产生的空腔,所以能够进行热处理。这些铸件 可获得平均15%的延伸率,而传统的铝合金压铸件只 有3%的延伸率。


传统上,真空压铸工艺被限制在小批量汽车生产中 使用,但是,因其具备了满足缓冲区域要求的能力, 为汽车制造商带来了利益,尤其是在MMLV项目中, 使汽车重量减轻了25%,同时通过了严格的正面碰撞 安全测试。


为大批量生产的车型提供零部件的OEM供应商对结 构压铸件的兴趣,提高了真空压铸件在市场的产能。8 月,Magna公司宣布了在阿拉巴马州伯明翰的KAM- TEK工厂新建铝合金铸造厂的计划。KAMTEK工厂将 按北美和国外OEM客户的需求生产轻量化结构铸件。 “我们已经得到了越来越多的客户对于采用这项技 术生产汽车零部件的咨询,”Skszek说。 MMLV概念车中使用的压铸件包含左右前减振器, 左右铰链柱,左右加强梁,以及左右后中梁铸件。 Magna公司称,减振器是最常见的真空压铸壳体铸 件。原来需要数个合金钢材质的零部件组成的结构件 用单一的铝合金铸件代替,重量减轻40%。使用铝合 金铸件,减振器的重量从原来的 7.5磅(3.4kg)减少为 4.6磅(2kg)。


位于铰链柱下方的加强梁对于铸件的性能要求最 高。作为车辆前方的底盘加固件,在碰撞发生时,它 应不侵占乘客位的脚下空间。真空压铸工艺的铸件经 过热处理后更具刚性,增强了MMLV车身结构的扭转 负载能力和抗扭刚度。FEA分析结果显示,汽车加强 梁铸件的挤压特性比原设计更好。


铝合金压铸的加强梁替代原来由5个合金钢冲压 件组成的加强梁,重量从13磅(5.9kg)减少到10磅 (4.5kg)。


铰链柱铸件代替了原来的5个合金钢冲压件的组装 件,比原设计件轻大约35%,重量从9.8磅(4.4kg)减 少到7.4磅(3.4kg)。最终,中部横梁铸件的设计将由 12个零部件组成的后减振器和横梁集成为单一铸件, 重量从12.5磅(5.7kg)降到9.2磅 (4.2kg)。


The MMLV kick down rail replaced five steel stampings and is about 25% lighter.


MMLV加强梁替代原来由5个合金钢 冲压件组成的加强梁,重量减轻25 %。


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