重型板式给料机论文(12)

洛阳理工学院毕业设计论文 unmeasurably experimentally, are approximated by the proposed finite element model, these results being in good agreement with reported results of other finite element orthogonal cutting models.

Contours of equivalent plastic strain at steady state, revealing the work-hardening of the chip and the residual deformation in the workpiece, are shown in Fig.4.A maximum value of 1.86 of the plastic strain was obtained at the chip-tool interface, probably due to the severe deformation of the material. At the primary deformation zone, the values of the plastic strain are smaller, starting from a value of 1.273 at the surface of the cut workpiece and decreasing gradually to zero at the sub-surface layer.

Fig.4. Contours of equivalent plastic strain at steady state in simulated orthogonal machining.

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洛阳理工学院毕业设计论文 Fig.5. Contours of plastic strain-rate at steady state in simulated orthogonal machining.

The corresponding contours of the effective plastic strainrate at steady state are shown in Fig.5.High strain-rates are obtained along the primary deformation zone, with a maximum value of about 6×10^3 s -1 at the tool tip region. The concentration of high strain-rates at the shear plane may be attributed to the fact that the material there suddenly changes its flow direction, as indicated in Fig.1.

Fig.6. Contours of temperature after a tool path of 2.58 mm in simulated orthogonal machining.

Fig.7. Contours of the equivalent stress at steady state in simulated orthogonal machining.

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洛阳理工学院毕业设计论文 The temperature distribution in the workpiece, chip and tool after a tool path of 2.58 mm, is shown in Fig.6.The highest temperatures in the chip appear at the secondary deformation zone, with a maximum value of 3608C attained in the sliding region. The temperature rise in metal cutting is mainly due to plastic work that is converted into heat. Therefore, taking into account that the highest plastic strains appear at the secondary deformation zone, see Fig.4,it is apparent that the maximum temperatures should be encountered in the same regime. As far as the tool is concerned, the highest temperature attained was 2868C, just above the tool tip. The location of the maximum temperatures in the chip and tool agrees qualitatively with reported experimental observations [22].

Contours of equivalent stress during steady state are shown in Fig.7.A maximum value of 933 MPa was achieved at the secondary deformation zone, near to the sticking region; the related maximum value of stress in the primary deformation zone was 817 MPa, whilst a gradual decrease of stress under the uncut surface, ranging from 700 to 117 MPa, was calculated. …… 此处隐藏：684字，全部文档内容请下载后查看。喜欢就下载吧 ……