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高精度矫直辊辊型设计及工艺参数控制是二辊矫直机的核心技术。为了满足高精度棒材矫直要求,在辊型设计过程中依据矫直辊磨损状态、弹塑性理论、塑性变形硬化系数求解模型及中性层偏移理论,提出“凹三凸二”分段辊型的矫直辊组合形式及辊型设计方法。在此基础上,根据棒材与矫直辊的局部线接触状态,建立棒材二辊矫直倾角及辊缝估算模型,进而探讨二辊矫直工艺参数(倾角、辊缝、矫直速度和导板间距)的变化规律和控制策略,并给出具体设计实例和有限元模拟分析。从矫直力、塑性变形深度、直线度及残余应力等角度,证明该辊型设计方法和工艺控制策略的有效性,且现场试验矫后的棒材直线度小于1 mm/m,完全满足棒材高精度矫直标准。 相似文献
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为了深入研究塑性强化材料在平行辊式矫直过程中一次反弯与二次反弯特性的关系,根据工程弹塑性力学的基本原理,建立基于强化弹塑性材料辊式矫直弯曲力学模型。通过解析法描述两次反弯过程中的应力关系,给出辊式矫直过程中截面弯曲过程材料残余应力分布、弯矩比、加载应力变化过程。证明两次反弯过程中经历一次反弯后,二次反弯截面弯矩比与曲率比不再是原有简单M-C关系,而是与一次弯曲曲率比、二次弯曲曲率比与强化系数相关的函数。理论上证明原有弯曲理论不再完全适用于多次连续反弯矫直过程。解析结果表明,辊式矫直过程中经历二次反弯的材料截面弹性极限弯矩值下降,矫直弯曲减小,回弹比增大。同种材料考虑强化与不考虑强化矫直后残余应力均方差分别为71.2与65.6,回弹比均值分别为0.49和0.43。 相似文献
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介绍了一种多棍棒材矫直机预控参数在线自动整定方法,阐述了采用人机界面实现矫直辊压下及转角预控参数高精度自动调整.可用作金属轧制矫直设备,能有效提高金属棒材生产成品矫直精度. 相似文献
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滚子修形对轴承性能影响的研究 总被引:3,自引:2,他引:3
为了提高滚子轴承的工作寿命和承载能力,普遍采用滚子修形。本文研究了直线滚子、全凸滚子、凸弧-直线滚子和对数滚子的母线方程及修形参数,在相同的工况条件下,分析计算了这四种滚子的接触应力沿接触线的变化情况,得出了对数滚子具有最佳受载状态的结论。并以提高轴承工作寿命为目标,建立了确定最佳修形量的数学模型,分析了修形量对轴承受载特性的影响,得出了滚子合理修形可以显著改善高速滚子轴承受载状态的结论 相似文献
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This paper reports on the roller skew in tapered roller bearings monitored by contact potential difference probes. The effect of the load, rotational speed, and viscosity of lubricant on roller skew angle, along with the variation of bearing torque with the running conditions, were measured on a LM501300 bearing. Two greases (SHC15 and SHC460) were used to lubricate the bearing. The skew angles were found to vary from 0.15° to 0.6°. The results indicate that the skew angle depends on the friction force at the roller-rib interface. An empirical equation is derived which relates the skew angle to the bearing operational parameters. 相似文献
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Tests were run to compare the fatigue life of two-row tapered roller bearings to that of spherical roller bearings. Both bearing types had an outer diameter of 110 mm with the spherical roller bearing having a 22 percent larger dynamic radial load rating than the tapered roller bearings. All tests were run at 165 percent of the respective two-row dynamic radial load ratings. The results show that both the indirect mounting (double cup or outer ring) and the direct mounting (double cone or inner ring) tapered roller bearings gave significantly better fatigue lives than the spherical roller bearings. These results appear to contradict the present ISO 281 standard which assigns a 1.15 bm rating factor to spherical roller bearings compared to a bm rating factor of 1.10 for that of tapered roller bearings. 相似文献
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在对棒材精轧机常规Ni-Mo贝氏体球墨铸铁复合轧辊宏观及微观组织进行分析的基础上,找出了导致轧辊表层剥落失效的主要原因是轧辊组织中贝氏体质量分数低、碳化物形态分布不合理和石墨形态不圆整。在此基础上,通过对常规贝氏体球墨铸铁复合轧辊合金化元素质量分数的优化(镍、铜、铌复合合金化),达到优化轧辊组织与性能的目的。改良后轧辊的组织更为细小,其碳化物形态得到了显著改善;同时合金元素的复合加入显著提高了材料中贝氏体的强度,其冲击韧度、挠度、断面收缩率、断后伸长率等指标均较常规Ni-Mo球墨铸铁有明显的改善,因而能够显著延长轧辊的使用寿命,有效降低钢材的生产成本。 相似文献
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本文介绍一种新型齿轮箱一多级行星齿轮箱,和一般卷板机比较,它的驱动结构简单,这种齿轮箱易于制造、传动性能良好。 相似文献
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Cylindrical roller bearings typically employ roller profile modification to equalize the load distribution, minimize the stress concentration at roller ends, and allow for a small amount of misalignment. The 1947 Lundberg-Palmgren analysis reported an inverse fourth-power relation between load and life for roller bearings with line contact. In 1952, Lundberg and Palmgren changed their load–life exponent to 10/3 for roller bearings, assuming mixed line and point contacts. The effect of the roller–crown profile was reanalyzed in this article to determine the actual load–life relation for modified roller profiles. For uncrowned rollers (line contact), the load–life exponent is p = 4, in agreement with the 1947 Lundberg-Palmgren value, but crowning reduces the value of the exponent, p. The lives of modern roller bearings made from vacuum-processed steels significantly exceed those predicted by the Lundberg-Palmgren theory. The Zaretsky rolling-element bearing life model of 1996 produces a load–life exponent of p = 5 for flat rollers, which is more consistent with test data. For the Zaretsky model with fully crowned rollers, p = 4.3. For an aerospace profile and chamfered rollers, p = 4.6. Using the 1952 Lundberg-Palmgren value p = 10/3, the value incorporated in ANSI/ABMA and ISO bearing standards, can create significant life calculation errors for roller bearings. 相似文献
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行星式滚柱丝杠副的运动特性及参数选择 总被引:4,自引:0,他引:4
对行星式滚柱丝杠副的工作原理、运动特性及几何关系进行分析研究,推导出表达运动关系的方程式,给出了其各参数选择的公式,尤其是滚柱两端齿轮齿数的计算方法。 相似文献
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Luo Yixin Department of Resources Engineering Xiangtan Polytechnic Uneversity Xiangtan China 《机械工程学报(英文版)》2002,(1)
0 INTRODUCTION1It is difficult to manufacture the spring of commune roller orientation clutch. When clutch works, roller often invades the spring space, which make the clutch have no direction. In addition roller's being worn-out and broken may affect the life of clutch[1] According to these circam-stances, we have designed a new roller clutch. The clutch has no springs and acquired Chinese patent, and has made a lot of samples.There are some defects in the conventional method of the des… 相似文献
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