外文翻译--万向节十字轴总成失效分析

附 录 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 occ urred 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. 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，