轻型货车传动轴完整设计-轻型卡车【三维CATIA模型】【含4张cad图纸+文档全套资料】
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外文文献
Cross-axis gimbal assembly Failure Analysis
The main function of joints in different axis passing between the rotating shaft torque, it has been widely used in various types of truck axle shaft connected between the cross section, usually in the course of cross-axis universal joint of the Needle Roller Bearings for rotary movement is not, but for the rotation of the swing movement, the load cycle changes submitted. Based on the heavy-duty vehicle WX0082 Cross-axis gimbal assembly of less than life pieces of the failure mode of failure, failure, structural parameters and materials used and the performance of finite element analysis and other methods to conduct a comprehensive comparative analysis of product performance a design improvement.
1. Oblique imprint
The author of a company from the provision of three packs of the three packs of Service returned failure cases observed that the cross-axis oblique journal imprint is relatively serious, bearing rings also produce the inner wall of the imprint, but the depth of cross-axis than the light. By the analysis of joints installed on the bearing assembly, when the total space bearing a larger circle, the needle easily skewed, with the result that journal have a cross-axis tilt angle with the axis of the embossing, the embossing depth of the expansion of more deep, the needle will not be able to spin, thus increasing frictional resistance, exacerbated by the extension of indentation. The total circumference of its appropriate space should be controlled in the range of 0.1 ~ 0.4mm inside, JB/T3232 in a given space for a total circumference of not more than 0.5mm.
2. Fatigue spalling
Shaft angle in the use of a smaller state, universal joint assembly of the needle bearing journal diameter and cross-axis angle in the framework of repeated smaller swing, when the cross-axis with the bearing radial clearance with the wear and tear expansion will lead to concentration of load, the load will be large local indentation fatigue prematurely in order to develop into a large area off the fatigue. Especially in the cross-axis the first axis, the stress concentration due to the impact of parts of their set was almost all the chamfering eat, severe high temperature sintering under a state of the phenomenon.
Because users do not use lubricants or as a result of time added on the universal joints bearings sealed properly, resulting in early loss of oil-bearing materials as well as the dust temperature intolerance, lip oil seals in the winter cold weather aging cracks under so that the early loss of grease. In addition, the universal joint assembly less oil in operation due to high temperature generated, so that shaft bearings and killed, resulting in a broken needle and the damage to seals and dust jacket, traces of ferrule surface ablation, the failure mode of both failure mode is non-normal.
4. Needle failure
I lapsed from the universal joint assembly observed in the sample found that the majority of needle point of the surface there are Ma, Ma Hang, and large-scale fatigue spalling, a small number of needle head was broken, a small number of needle from the needle about 1.5mm Department head Ma Hang, and the existence of a larger phenomenon of bite wounds, the majority of needle fracture fracture from here, this occurrence of the main bearing structure and the size parameters and the circular design of the total gap.
5. Gasket failure
Gasket is the first universal joint assembly of the components failure, the form of gasket failure nylon fracture and wear pads. I carefully analyzed samples gasket failure found that the outer gasket has obvious cracks, gasket has cracks and debris outside. Obviously, the gasket is the gasket by the external force resulting in rise of the local stress concentration, once the gasket external damage to the axial force will be borne by the rest of the pads to bear, the bear pads per unit area will increase the power, the entire pad tablets to be broken. Hence the need for well-designed shape and bearing structure pads. At the same time, each gasket failure due to damage and wear has been associated with failure, the gasket material must be selected high strength and wear resistance of materials.
6. Cross-axis fracture
Cross shaft fracture is usually a serious overloading the user under the premise of the factors or unusual conditions occur, as joints in the design of the Department of full compliance with the standards of universal joints JB/T8925-2008 static torsional strength safety factor of 2.5 times the provisions of However, OEMs fault occurred during the three packs of the proportion of the total failure still accounts for 2% ~ 5% of such cases is sudden, but inevitable, universal joints and therefore the static torsional strength of match, we must maximum output torque in the engine 3 times more specific in order to avoid overloading caused the emergence of sudden failure.
7. Metallographic test analysis
Cases of failure to carry out physical and chemical analysis, respectively, in the cross shaft, ferrule and needle selection of the typical characteristics of the location of the site, cutting under the specimen and along the vertical cross-section metallographic sample preparation, the microstructure-level qualified. To determine the cross shaft, ferrule and the center needle hardness, respectively, by micro-hardness of various parts of a gradient distribution of Vickers hardness measured, and its basically in line with the hardness of the hardness distribution. Check the cross-axis universal joints, a test piece of the outer ring and a number of needle samples in 50% hydrochloric acid aqueous solution heated to 70 ~ 80 ℃, heating of about 1h, check for hot acid found in various parts use burn phenomenon exists. This burn is to determine universal joints sealed as a result of poor performance and fat loss properties of the oil well, resulting in fever bearing universal joints burn too soon after the failure of the parts.
中文翻译
万向节十字轴总成失效分析
万向节的主要作用是在不同轴线上的轴之间传递旋转转矩,它被广泛应用于各类卡车的传动轴联接轴节叉之间,通常在使用过程中万向节十字轴上的滚针轴承不是作旋转运动,而是作旋转摆动的运动,其载荷呈交变的周期变化。本文是通过对重型载车用WX0082万向节十字轴总成寿命不足失效件的失效形式、失效原因进行分析。 分析结果如下:
1.斜压印
从某公司三包服务处提供的三包退回失效件中观察到,十字轴轴颈斜压印情况比较严重,轴承套圈内壁也产生相应的压印,但深度要比十字轴轻。经分析,安装在万向节总成上的轴承,当轴承圆周总间隙较大时,滚针易产生歪斜,致使十字轴轴颈产生与轴线倾斜一定角度的压印,当压印深度扩展较深时,滚针就不能自转,因此使摩擦阻力增大,加剧压痕的延伸。其合适的圆周总间隙应控制在0.1~0.4mm范围内,JB/T3232中给定的圆周总间隙为不超过0.5mm。
2.疲劳剥落
在传动轴摆角较小的使用状态下,万向节总成上的滚针轴承内径与十字轴轴颈在较小角度范围内反复摆动,当十字轴与轴承径向游隙随着磨损而扩大时,会导致产品载荷集中,载荷大的地方就会过早地产生疲劳压痕,从而发展成为大面积的疲劳剥落。特别是在十字轴轴头处,由于应力集中影响,其受载部位的倒角几乎全部被啃掉,严重时会在高温状态下出现烧结现象。
3.缺油烧蚀
由于在使用过程中用户不按期加注润滑油或由于万向节上的轴承密封不好,导致轴承早期失油以及防尘罩材料不耐低温,油封唇口在冬季寒冷气候下产生老化裂纹,使润滑脂早期流失。另外,万向节总成在运行中因缺油而产生高温,使轴承与轴径咬死,致使滚针折断以及密封和防尘外罩损坏,套圈表面有烧蚀痕迹,这种失效形式均属于非正常失效形式。
4.滚针失效
从万向节总成失效样品中观察发现,大多数滚针表面都存在麻点、麻坑和大面积疲劳剥落,少数滚针头部被折断,少数滚针在离滚针头部1.5mm左右处存在较大麻坑和啃伤现象,滚针断裂大部分也是从此处断裂,这种情况的发生主要与轴承结构尺寸参数及圆周总间隙设计有关。
5.垫片失效
垫片是万向节总成中首先失效的部件,垫片失效形式为尼龙垫片断裂和磨损。仔细分析失效垫片样品发现,垫片的外围有明显的裂纹,垫片外围有裂纹及碎片。很明显,垫片外围是垫片受涨力致使应力集中的地方,一旦垫片外围破坏,其轴向力将全部由余下的垫片承受,垫片单位面积上承受的力将增加,整个垫片将被破坏。因此需要设计合理的垫片形状和轴承结构。同时,由于垫片每次失效破坏都伴随着磨损失效,所以垫片材料必须选取强度和耐磨性较高的材料。
6.十字轴断裂
十字轴的断裂一般是在用户严重超载前提下或异常因素条件下发生,因为万向节在设计时完全遵循部标准JB/T8925-2008中万向节静扭强度安全系数2.5倍的规定,但在主机厂三包期内发生的故障比例仍占总故障的2%~5%,此种情况虽然是突发性的,但也不可避免,因此对万向节的静扭强度匹配,必须在发动机最大输出扭矩的3倍以上才能避免特殊超载引起的突发性故障的出现。
7.金相检验分析
对失效件进行理化分析,分别在十字轴、套圈和滚针的典型部位选择特征位置,切割下试件,并沿纵截面制取金相试样,其金相组织级别合格。为确定十字轴、套圈及滚针的心部硬度,用显微硬度计分别对各零件进行了维氏硬度梯度分布测定,其硬度也基本符合硬度分布规律。取万向节的十字轴、外圈各一试件及数个滚针试件,在50%盐酸水溶液中加热至70~80℃,加热约1h,作热酸洗检查,结果发现各零件在使用过程中都存在烧伤现象。这种烧伤现象判断是由于万向节密封性能差失油及油脂性能不好,导致万向节轴承发热后各零件烧伤过早失效。
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