弹簧设计.ppt

1、弹簧设计 Spring Design,一 概述 summary,弹簧的分类 spring classification 弹簧的分类有多种，一般按照如下区分: Spring has a variety of classification. Generally, spring is classified as the following ： 根据使用的材料分 According to the using material：,铁制弹簧 Ferrous springs,非铁金属弹簧 Non-ferrous springs,碳素钢弹簧 Carbon steel springs,合金钢弹簧 Alloy s

2、teel springs,不锈钢弹簧 Stainless steel springs,铜合金弹簧 Cooper alloy springs,镍合金弹簧 Nickel alloy springs,其他 The others,金属材料 Metal material,其他 The others,一 概述 summary,非金属材料 Nonmetal material,螺旋弹簧 Helical springs,板（片）弹簧 Leaf springs,特种弹簧 Special springs,压缩弹簧compression springs,拉伸弹簧compression springs,扭转弹簧 tor

3、sion springs,橡胶弹簧rubber springs,流体弹簧fluid springs,合成树脂弹簧synthetic resin springs,其他类弹簧the other springs,根据形状分：According to the appearance.,其他类弹簧the other springs,常用的三种弹簧 The common springs,一 概述 summary,压缩弹簧 Compression springs Compression Springs are springs which absorb and store energy by offering

4、resistance to a pushing force. Most compression springs are a straight columniform spring made of round wire. 压缩弹簧是通过推压弹簧来存储能量的，大部分的压簧是直的圆柱型圆钢丝弹簧。,拉伸弹簧 Extension springs Extension Springs are springs which absorb and store energy by offering resistance to a pulling force . Typically, extension sprin

5、gs are made from round wire and are close wound with initial tension. 拉伸弹簧是通过拉弹簧来存储能量的，在初始状态，大部分拉簧是圆钢丝且弹簧 钢丝之间是并紧没有间隙的。,常用的三种弹簧的介绍 The introduction of three common springs,一 概述 summary,扭转弹簧 torsion springs,A torsion spring is a spring that works by torsion or twisting; that is, a flexible elastic ob

6、ject that stores mechanical energy when it is twisted. The arms of the torsion springs rotate about the central axis.,扭转弹簧力是通过是通过扭转弹簧来存储能量的，弹簧的臂是围绕一个中心轴在转动的。,二、弹簧的设计应力 Some design stress of springs,张应力Tension stress 张应力是由于轴向拉升材料所产生的应力。 Tension stress is the stress state caused by an applied load tha

7、t tends to elongate the material in the axis of the applied load, in the other words the stress caused by pilling the material. 压应力Compression stress 压应力是由于轴向压缩材料所产生的应力。 Compression stress is the stress state caused by an applied load that acts to reduce the length of material in the axis of the app

8、lied load, in other words the stress state caused by squeezing the material. 张应力和压应力的公式如下 The formulas as following： =F/A 其中， F为力(N) / A为面积(m2) where F is force (N) acting on an area A (m2);,Tension stress,compression stress,二、弹簧的设计应力 Some design stress of springs,弯曲应力 Bending stress 弯曲应力是由于弯曲材料所产生的

9、应力。 Bending stress is the stress state caused by an applied load that tends to bend the material in the axis of the applied load, in the other words the stress caused by bending the material. 对于扭簧，它给出的是扭力，但是有限元上主要应力为弯曲应力。 Torsion spring give torsional fore, but the wire are loaded in bending stress.

10、,Bending stress,注意！Tip!,二、弹簧的设计应力 Some design stress of springs,扭转应力 Torsional stress 扭转应力是由一对平行的方向相反的力作用材料上所产生的应力。 Torsional stress is state caused by a pair of opposing forces acting along parallel lines of action through the material。 对于压簧和拉簧， 它给出的是轴向的力，但是有限元上主要应力为扭转应力。 Tension and compression sp

11、rings give axial loads, but the wire are loaded in torsional stress.,注意！Tip!,torsional stress,二、弹簧的设计应力 Some design stress of springs,疲劳强度Fatigue strength 疲劳强度是指材料在无限多次交变载荷作用下而不破坏的最大应力称为疲劳 强度。 Fatigue strength is the maximum stress level that a material can withstand an infinite number of cycles bef

12、ore damage.,S-N curve for steel,三、弹簧材料的强度和的特性 Strength of materials and material properties,3.1 材料的几个强度定义 Definitions of some strength of materials ： 极限抗拉强度 Ultimate tensile strength-Sut（单位unit：MPa） 抗拉强度指材料在拉断前承受最大应力值. Ultimate tensile strength is defined as the stress at which a material begins to

13、break. (The maximum stress a material can withstand when subjected to tension, Sut可以通过查询手册得到，也可以通过以下公式计算： The values of Sut can select from some spring handbooks, also can calculate according to the following formulas. Sut=196000/d0.146 (Unit:psi-单位为英制的) Sut=1351/（d/25.4）0.146 (Unit:MPa) 其中,d为弹簧材料的线

14、经。d means wire diameter.,三、弹簧材料的强度和的特性 Strength of materials and material properties,材料的几个强度定义 Definitions of some strength of materials ： 屈服强度 Yield strength-Sy （单位unit：MPa） 屈服强度是材料开始发生永久变形或者塑性变形的应力。 The yield strength is defined as the stress at which a material begins to deform permanently or pla

15、stically. 剪切强度 Shear strength-Ssy （单位unit：MPa） 剪切强度是指材料承受剪切力的应力. Shear strength is defined as the stress at which a material fails in shear. 三者关系见下图（The relationship as following figure)：,三、弹簧材料的强度和的特性 Strength of materials and material properties,如：对于琴钢丝的材料，有如下关系： For music wire, it has the followi

16、ng Relationship: Sy=0.75Sut Ssy=0.577Sy 对于设计扭簧的时候，材料主要承受的 应力为弯曲应力，所以设计应力选用Sy；但 设计拉伸和压缩弹簧时，设计应力选用Ssy. For torsion spring, the wire are loaded in bending stress, so the design stress should be choose Sy, but the compression and extension spring should be choose Ssy.,Figure of stress-strain curve,三、弹簧材

17、料的强度和的特性 Strength of materials and material properties,以下是一些常用材料的Sut值 Some Sut for the common material as following：,设计弹簧时，初始的计算可以选用上表的数值。 Select values from the above table for initial calculation of spring.,三、弹簧材料的强度和的特性 Strength of materials and material properties,3.2 弹性模量 Modulus of elasticity

18、弹性模量是应力-应变曲线直线部分的斜率 。 Modulus of elasticity is defined as the slope of its stress-strain curve in the elastic deformation,Figure of Stress-strain curve,=Stress/Strain 单位(uint)：MPa,三、弹簧材料的强度和的特性 Strength of materials and material properties,两者之间的关系 （the relationship between the two modulus)： E=2G(1+r

19、) 其中，r为泊松比 where, r stands for poisson ratio,每种材料都有两种弹性模量Every material has two modulus of elasticity :,拉伸弹性模量（简称弹性模量）E， 是用来设计扭转弹簧。 Tensile Elasticity modulus (Youngs modulus E) which used to design torsion spring,切变弹性模量(简称切变模量)G， 是用在拉伸或压缩弹簧。 Shear modulus (G) which used to design of compression and

20、 extension spring.,三、弹簧材料的强度和的特性 Strength of materials and material properties,琴钢丝的一些特性Some properties of music wire as following:,拉（压）簧设计选用,扭簧设计选用,四、弹簧设计需要考虑的参数 Design considerations for springs,1 根据使用的要求， 选择合适的弹簧的形状，种类和端部结构。 Select the right kind of springs, the appearance and end of springs accor

21、ding to the using requirements. 2 根据给定的空间，定出弹簧的外形轮廓尺寸。如，允许的最大外径， 最小内 径，变形量，弹簧刚度，弹簧的力值等。 According to the space, the basic sizes of spring could be determined. For example, the maximum out diameter (mm), the minimum inner diameter (mm), spring rate,the maximum deflections (mm) and the maximum loads (

22、N) during assembly. 3 根据使用情况， 如对工作温度，环境介质，使用寿命等选择合适的材料。 Select the right material according to the operating temperature, environmental media, endurance lift and so on. 4 根据使用条件的载荷特性决定材料的许用应力。 Decide the maximum allowable stress according to the loads.,五、弹簧设计公式和示例 Formula and examples,1 拉伸弹簧和压缩弹簧设计的

23、公式 Design formulas of compression and extension springs (1) 弹簧刚度Spring rate k：,k也可以用下列公式计算： k also be calculate as following formula: k=P/F 注：当选择P,F计算时，需要大于弹簧变形量的20%，小于弹簧变形量的80%。如右图中P1-P2及F1-F2之间。,Note: When choose the P and F to calculate rate, the values should between 20 percent and 80 percent of

24、 spring deflection.,（2）设计扭应力Design torsional stress S： (3) 曲度修正系数 The Wahl correction factor K:,Sk =KS,( C=D/d ),P值必需选用弹簧的最大 载荷在最大变形量下或者 固体长度时。P=k*(L-H) The P must be the maximum load at maximum deflection or solid height.,对于拉伸弹簧，设计时需要注意端部的设计。 We should pay attention to the designing of extension sp

25、ring ends, the hooks need to stand the bending stress.,五、弹簧设计公式和示例 Formula and examples,上公式中的各参数的含义 The meaning of each parameter： k 弹簧刚度（Spring rate) (常数 content） P- 轴向载荷（Loads) （N) F-变形量（Deflection) (mm) D-中径（Mean coil diameter) (mm) d-材料线径 (Wire diameter) (mm) G-切边模量 (Shear modulus) (MPa) na-有效圈数

26、 ( Number of active coils) S- 扭转应力 (Torsional stress) (MPa) (未修正的应力uncorrected stress) Sk-修正扭应力 (Corrected stress) (MPa) C-弹簧缠绕比 (Spring index) N-总圈数 (Number of total coils) L-弹簧长度 (Spring length) (mm) H-弹簧固体长度 (Solid height of spring) (mm) P-节距 (Pitch) (mm),五、弹簧设计公式和示例 Formula and examples,下表中公式可以计

27、算na,N,H,P,L ： The table below gives formulas for calculating na,N,H,P and L.,五、弹簧设计公式和示例 Formula and examples,例 Example： 设计一压弹簧，外径为23.5mm,自由长度为43.5mm, 在长度为32.46mm时的 载荷量为222.422.2N,断部并紧并磨平，最大的固体长度为26.92mm,材料为 油淬火钢丝。,P=222.4N,五、弹簧设计公式和示例 Formula and examples,计算：弹簧刚度：k=P/F=222.4/(43.5-32.46)=20.14N/mm

28、弹簧在固体长度时的载荷量：P=F*k=20.14（43.5-26.92）=334N 弹簧的最大设计应力值为0.451386MPa=621MPa 假设弹簧的线径为2.54mm (小于外径23.5mm），则有弹簧的中径为 23.5-2.54=20.96mm 根据公式 ：,五、弹簧设计公式和示例 Formula and examples,可算出：d=3.07mm 建议使用 d=3.18mm的线径,此时中径D=20.32mm 有效圈数：根据公式：,na=6，所以总圈数N=6+2=8 固体状态的长度为H=3.188=25.4mm 小于给定的26.92mm,可以接受。 根据公式 计算扭应力值：S=540MPa C=20.32/3.18=6.4 曲度修正系数：K=1.23 Sk=1.23540=664MPa 而材料的最大许可应力为0.451517=683MPa 大于Sk, 所以设计在材料的应力范围之内。,五、弹簧设计公式和示例 Formula and examples,2 扭簧设计的公式 Design formulas of torsion springs (1) 扭力矩 Moment or torque M：,(2) 弯曲应力 Bendin