楔尖圆角对楔横轧4Cr9Si2气门成形影响分析

Influence Analysis of Wedging Tip Fillet for Forming in the Process of Cross Wedge Rolling 4Cr9Si2 Valve

借助刚塑性有限元软件DEFORM-3D针对4Cr9Si2马氏体耐热钢楔横轧成形过程进行有限元数值模拟,得到楔横轧工艺参数——楔尖圆角对楔横轧4Cr9Si2马氏体耐热钢轧件对称中心的心部缺陷以及轧件表面的表面螺旋痕和对称中心横截面拉细的影响规律:随着楔尖圆角的增大,轧件表面径向力的数值得到减小,从而使横楔轧轧件表面螺旋痕将会明显减小;当楔尖圆角增大后,轧件心部横向应力σy和切应力τxy的持续时间将增加,同时,楔横轧轧件心部第一主应力σ1的方向将会发生改变,使轧件心部金属朝横向y方向流动,从而增加了楔横轧轧件心部缺陷产生的可能性;楔尖圆角增大,轧件轴向力Fz的数值将会减少,从而能够改善对称中心横截面拉细状况。进行4Cr9Si2马氏体钢的楔横轧轧制试验,验证有限元模拟结果的可靠性,并通过增大展宽角获得合格的轧件。

Forming process of 4Cr9Si2 martensite refractory steel by cross wedge rolling is simulated by means of rigid-plastic DEFORM-3D software. The influence regularities of cross wedge rolling technical parameter—wedging tip fillet for surface spiral, internal defeats, size reduction on center of symmetry are obtained：It is obvious that surface spiral will be reduced with increasing of the wedging tip fillet due to surface radial force decrease; The duration time of transverse stress and shear stress will be increased, meanwhile the direction of max stress will be changed and metal flow direction will toward transverse direction with increasing of the wedging tip fillet, and consequently these factors lead to higher possibility of internal defeats; Size reduction on center of symmetry will be improved due to the value of axial forceFz decrease with increase of wedging tip fillet. Rolling experiments are carried out to verify the reliability of the simulation results, and qualified part is obtained by means of increasing stretching angle.