1、广东技术师范学院天河学院 本科毕业设计外文翻译译文 学生姓名 陈剑锋 院（系） 广东技术师范学院天河学院 专业班级 机械设计制造及其自动化 指导教师 蒋文明 完成日期 2011.12.30 外文出处 ： http:/en.wikipedia.org/wiki/Leaf_spring Leaf spring history There were a variety of leaf springs, usually employing the word elliptical. Elliptical or full elliptical leaf springs referred to two ci
2、rcular arcs linked at their tips. This was joined to the frame at the top center of the upper arc, the bottom center was joined to the live suspension components, such as a solid front axle. Additional suspension components, such as trailing arms, would be needed for this design, but not for semi-el
3、liptical leaf springs as used in the Hotchkiss drive. That employed the lower arc, hence its name. Quarter-elliptic springs often had the thickest part of thestack of leaves stuck into the rear end of the side pieces of a short ladder frame, with the free end attached to the differential, as in the
4、Austin Seven of the 1920s. As an example of non-elliptic leaf springs, the Ford Model T had multiple leaf springs over its differential that were curved in the shape of a yoke. As a substitute for dampers(shock absorbers), some manufacturers laid non-metallic sheets in between the metal leaves,such
5、as wood. Leaf springs were very common on automobiles, right up to the 1970s in Europe and Japan and late 70s in America when the move to front-wheel drive, and more sophisticated suspension designs saw automobile manufacturers use coil springs instead. Today leaf springs are still used in heavy com
6、mercial vehicles such as vans and trucks, SUVs, and railway carriages. For heavy vehicles, they have the advantage of spreading the load more widely over the vehicles chassis, whereas coil springs transfer it to a single point. Unlike coil springs, leaf springs also locate the rear axle, eliminating
7、 the need for trailing arms and a Panhard rod, thereby saving cost and weight in a simple live axle rear suspension. A more modern implementation is the parabolic leaf spring. This design is characterised by fewer leaves whose thickness varies from centre to ends following a parabolic curve. In this
8、 design, inter-leaf friction is unwanted, and therefore there is only contact between the springs at the ends and at the centre where the axle is connected. Spacers prevent contact at other points. Aside from a weight saving, the main advantage of parabolic springs is their greater flexibility, whic
9、h translates into vehicle ride quality that approaches that of coil springs. There is a trade-off in the form of reduced load carrying capability, however. The characteristic of parabolic springs is better riding comfort and not as stiff as conventional multi-leaf springs. It is widely used on buses
10、 for better comfort. A further development by the British GKN company and by Chevrolet with the Corvette amongst others, is the move to composite plastic leaf springs. Typically when used in automobile suspension the leaf both supports an axle and locates/ partially locates the axle. This can lead t
11、o handling issues (such as axle tramp), as the flexible nature of the spring makes precise control of the unsprung mass of the axle difficult. Some suspension designs which use leaf springs do not use the leaf to locate the axle and do not have this drawback. The Fiat 128s rear suspension is an exam
12、ple. Figure 1 leaf spring a variety of shapes Leaf spring manufacturing process Multi-leaf springs are made as fllows: 1.Shearing of flat bar 2.Center hole punching/Drilling 3.End Heating process forming (hot & cold process) 1.Eye Forming/Wrapper Forming 2.Diamond cutting/end trimming/width cutting/end tapering 3.End punching/end grooving/end bending/end forging/eye grinding 4.Center hole punching/Drilling/nibbing 4.Heat Treatment 1.Heating 2.Camber forming 3.Quenching 4.Tempering
