|
|
- 2015
地脚螺栓蠕变松弛对大型数控机床 几何精度衰退的影响
|
Abstract:
针对大型数控机床地脚螺栓蠕变松弛的问题,建立了分布式螺栓预紧力和蠕变力的计算模型及螺栓顺序预紧和室温蠕变的模拟模型。计算模型中考虑了螺栓常温蠕变特征和螺栓孔单元间的弹性交互作用,量化分析时利用了模拟模型,以揭示蠕变松弛对机床几何精度衰退的影响规律。结合20℃环境温度下拉拔实验获得了8.8级T型地脚螺栓的3个蠕变系数,再经9 000 h蠕变模拟得到的地脚螺栓预紧力松弛比约为14.8％,床身导轨安装面直线度和平行度的相对衰退量分别为4.3 μm和2.8 μm。该结果表明,所建模型对大型数控机床基础件的螺栓预紧优化和几何精度保持能力的提升具有指导意义。
Aiming at anchor bolt creep relaxation of large CNC machine tools, a calculation model for preload and creep force of the distributed bolts is established, where both bolts creep at room temperature and elastic interaction among bolt？？hole units are taken into consideration. A simulation for anchor bolt sequential preload and creep is also conducted and utilized to reveal the influence of bolt creep relaxation on machine geometric accuracy decline quantitatively. Furthermore, three creep parameters of the 8.8 level T？？type anchor bolt are estimated via the drawing experiments under 20℃ ambient temperature. After 9 000 hours creep simulation, the anchor bolt preload relaxation reaches 14.8％, and the relative accuracy declines of straightness and parallelism of bed linear guide mounting surfaces get 4.3 μm and 2.8 μm, respectively. The developed model can be used for the fundamental parts bolt preload optimization and the geometric accuracy retention capability enhancement of large CNC machine tools
| [1] | 胡敏, 余常武, 张俊, 等. 数控机床基础大件精度保持性研究 ［J］. 西安交通大学学报, 2014, 48(6): 65？？73. |
| [2] | ［7］KIM N K. Performance of tension and compression anchors in weathered soil ［J］. ASCE Journal of Geotechnical and Geoenvironmental Engineering, 2003, 129(12): 1138？？1150. |
| [3] | HU Min, YU Changwu, ZHANG Jun, et al. Accuracy stability for large machine tool body ［J］. Journal of Xi’an Jiaotong University, 2014, 48(6): 65？？73. |
| [4] | ［2］涂善东, 轩福贞, 王卫泽. 高温蠕变与断裂评价的若干关键问题 ［J］. 金属学报, 2009, 45(7): 781？？787. |
| [5] | TU Shandong, XUAN Fuzhen, WANG Weize. Some critical issues in creep and fracture assessment at high temperature ［J］. Acta Metallurgica Sinica, 2009, 45(7): 781？？787. |
| [6] | ［3］KASSNER M E, SMITH K. Low temperature creep plasticity ［J］. Journal of Materials Research and Technology, 2014, 3(3): 280？？288. |
| [7] | ［4］DELHOMME F, DEBICKI G. Numerical modelling of anchor bolts under pullout and relaxation tests ［J］. Construction and Building Materials, 2010, 24(7): 1232？？1238. |
| [8] | ［5］FAN Q Y, LIU C L, YANG K Q, et al. Test study on creep character of anchor rod in argillaceous soft rock ［J］. Advanced Materials Research, 2012, 396: 565？？570. |
| [9] | ［6］XU H, WANG F, CHENG X. Pullout creep properties of grouted soil anchors ［J］. Journal of Central South University of Technology, 2007, 14: 474？？477. |
| [10] | ［8］杨国庆, 王飞, 洪军, 等. 螺栓被连接件轴向刚度高精度计算的半解析方法 ［J］. 西安交通大学学报, 2012, 46(9): 37？？42. |
| [11] | YANG Guoqing, WANG Fei, HONG Jun, et al. Semi？？analytical method for accurate evaluation of axial stiffness of bolted member ［J］. Journal of Xi’an Jiaotong University, 2012, 46(9): 37？？42. |
| [12] | ［9］GURINSKY M A. Long？？term strength of prestressed ground anchors in creep？？sensitive soils ［J］. ASEC Geotechnical Special Publication, 2002, 116(1): 37？？52. |
| [13] | ［10］MAXIMOV J T, DUNCHEVA G V, ANCHEV A P. An approach to modeling time？？dependent creep and residual stress relaxation around cold worked holes in aluminium alloys at room temperature ［J］. Engineering Failure Analysis, 2014, 45: 1？？14. |
