首页 >> FTI >>产品中心 >> Split Sleeve开缝内衬冷挤压
详细内容

Split Sleeve开缝内衬冷挤压


     The process works by imparting beneficial compressive residual stress around the hole. The action of drawing the mandrel through the starting hole causes a radial plastic flow of material and results in an annular zone of residual compressive stresses that extend up to one diameter beyond the edge of the hole as shown below.

      冷挤压开缝内衬的工艺原理是在孔周围引入有益的永久残留压应力。当芯棒被牵拉穿过初孔时,会引起材料径向塑性变形,形成一个残留压应力环状区域,该区域可延伸到超过孔边缘的一个直径。 

 

       The sleeve allows for one-sided processing and shields the hole from frictional forces generated by the high interference of the expansion mandrel. The residual stresses created by cold expansion significantly increase fatigue life by reducing the stress intensity factor and crack growth life by reducing the applied stress ratio at the hole. The magnitude of the peak residual compressive circumferential stress is about equal to the compressive yield stress for the material. The compressive stress zone spans one radius to one diameter from the edge of the hole, for diameters up to 1/2 inch for most materials. A balancing zone of tensile stresses lies beyond the circumferential compressive stress zone.

      开缝内衬允许单边操作,并且可以保护孔不受因芯棒挤压过程中产生的较大摩擦力的影响。冷挤压产生的残余压应力从两方面显著提升孔的疲劳寿命,一方面是降低应力强度因子,另一方面是通过减小孔的应力比延缓了裂纹生长。残留压应力切向力的峰值量级约等于材料的抗压屈服强度。残留压应力区域的范围是从孔的边缘延伸孔的一个半径到一个直径,对于多数材料,残留压应力区域的直径范围可至1/2英寸(12.7mm)张应力平衡的区域在切向压应力区之外。 

 

优点

Benefits of Split Sleeve Cold Expansion

开缝内衬冷挤压的优点 

lIn most cases, at least 3:1 fatigue life improvement

   大多数情况下,至少可以提高3倍的疲劳寿命 

lArrests small crack growth

    阻止小裂纹生长 

lCost effective alternative to redesign

    替代重新设计的成本效益 

lAdds no weight to structure

    不增加结构重量 

lSimple, one-sided operation

    工艺便捷,且可单边操作 

lWorks on all common aerospace materials

     应用于所有的常见航空材料 

lApplicable in both production and rework

     同时适用于生产和维修 

lCan be automated

      可实现自动化 

工具:

image.png

安装步骤:

12.jpg