共查询到20条相似文献,搜索用时 31 毫秒
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为提高U 型弯板生产效率、取消二次校形工序、方便卸料,设计制作了新结构的弯板弯曲模具。经对新结构的模具进行验证,模具结构合理,可补偿弯曲回弹,方便卸件,且增加了模具长度方向尺寸,一次可弯曲2 件弯板,提高生产效率。 相似文献
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目的研究椭圆形截面吊臂折弯时折弯间隙和折弯步进的关系。方法构建了一组吊臂折弯间隙、步进及折弯刀数的计算公式。结果结果表明,通过该公式所得折弯工艺参数与实践较吻合,同时,折弯效率也可以得到极大提高,以180 t产品为例,增大折弯步进后,折弯效率提高了20.3%~56.4%。结论建立了折弯间隙、折弯步进及折弯刀数的数学模型,可以据此得出所需的最优工艺参数,该模型对实际生产具有很好的工艺指导和支撑作用,可极大提高生产效率。 相似文献
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目的研究板材辊弯成形中弯曲角的分配方式,改善辊弯过程中出现的边波和纵向弯曲等各种缺陷,提高成形精度与质量。方法以小截面型材帽形辊弯件为研究对象,首先提出五边界条件成形角分配函数,并进行成形角度优化,得到最优的成形角分配方法。其次研究各弯曲角度分配方式对板材产生的主要缺陷如边波及纵向弯曲的影响规律,并进行辊弯成形实验验证。结果经过实验验证基于四边界条件的辊弯峰值纵向应变从4.15%降低到基于五边界条件的1.18%。验证了θN/3=33%×θ0时辊弯成形角度分配的合理性。结论基于优化的弯曲角分配方式的纵向应变、翘曲波动量和偏差值、最大高度偏差都小于其他分配方式的相应值,表现出其在成形工艺上的优越性。研究结果为合理设计类似帽形件或复杂截面形件的辊弯工艺提供一定的理论指导。 相似文献
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瓦楞纸板弯曲问题的基本方程 总被引:3,自引:3,他引:0
瓦楞纸板是夹层结构材料中的一种,可以将其作为正交各向异性的夹层板来进行研究.在基本假设的基础上,运用夹层板理论分析瓦楞纸板的弯曲问题,并建立其平衡控制方程,此方程可以应用于瓦楞纸板的压曲问题. 相似文献
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目的 对6061铝合金管开展三维自由弯曲成形的研究。方法 对不同弯曲半径的铝合金管进行了弯曲模拟成形,并根据模拟结果对铝合金管进行实际成形研究。结果 根据对6061铝合金管进行的弯曲半径为60, 70, 80 mm的有限元模拟成形结果,发现管材壁厚中性层向弯曲外侧发生明显偏移,且弯曲半径越小,向弯曲外侧的偏移量越大;管材内侧管壁增厚,最大增厚为17.2%,管材外侧壁厚减薄,最大减薄不超过4%,发现随着弯曲半径的减小,管材内侧增厚愈发明显,而减薄变化较小,同时对管材截面畸变进行分析,发现最大椭圆度不超过8%;通过对比模拟结果、实验结果与设计模型,发现管材模拟的弯曲半径最大偏差不超过8%,实验结果则不超过6.5%,而管材模拟的弯曲角度最大偏差不超过4.5%,实验结果则不超过3%,同时发现当弯曲较小时,内侧发生明显起皱,而弯曲外侧也有轻微壁厚减薄导致的畸变缺陷,这与模拟结果吻合。结论 管材壁厚中性层向弯曲外侧偏移与自由弯曲系统轴向推力PL有关,轴向推力使得管材的受压区域增加,而受拉区域减小,导致壁厚中性层外移;实验结果与模拟结果相吻合,验证了模拟对实验成形指导的可靠性。 相似文献
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基于特征的钣金折弯工序优化研究 总被引:2,自引:0,他引:2
针对钣金折弯工艺的特点,提出基于零件结构的FE图以及折弯工艺特征合并的二步折弯数据模型的构建方法.再依据启发式搜索规则、干涉约束等条件将零件折弯方案缩减在一个有限的折弯工序组合可行空间.最后考虑模具更换、工步数目、工件翻面和掉头次数等因素,可以直接计算得出最优的折弯工序. 相似文献
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A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The?EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. 相似文献
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《Composites Science and Technology》1986,27(3):225-248
An exact solution is presented for the problem of an infinite cantilever anisotropic plate with only a single plane of elastic symmetry parallel to the xy-plane and with elastic coefficients changing through the thickness, and the bending theory of anisotropic laminate plates is established. The solution is obtained in an inverse form and is then used to obtain an exact solution for the infinite cantilever anisotropic laminated plate. On the basis of this solution, an assumption about the in-plane displacements is made for a laminated plate of N layers, each of which possesses only a single plane of elastic symmetry parallel to the xy-plane. Under this assumption the in-plane displacements and transverse shear stresses are continuous between layers. Using the principle of minimum potential energy, the equilibrium equations and boundary conditions are obtained which are similar to the classical theory of laminated plate. The closed form solutions are compared with the exact solutions. The results show that the bending theory is in excellent agreement with the exact solution. 相似文献