工业机器人是一种新型的可以代替部分人工进行工业生产的高科技的智能机器设备。作为工业生产的机器人，无非可以用三个字来形容其要求：快、准、稳。
对于现在的机器人生产技术来说，快、准都更容易办到，而如果在做到快、稳的同时还要做到准，那就相对来说比较难了。
这里就定义了一个词：工业机器人的重复定位精度——工业机器人重复做某个动作（一般10--20次），每次与计划的位置的偏差的均值是它的重复定位精度，一般需用激光干涉仪来测量。
对于工业机器人来说，精度是相当重要的因素，它直接影响产品的质量与生产效率。而影响工业机器人的精度的主要因素就是轴承，那么什么样的轴承能使工业机器人会有较高的精度呢？
1、关键结构参数设计
工业机器人的轴承具有长寿命、高刚性、低摩擦的使用要求，所以在设计工业机器人的时候不仅要考虑尽可能大的额定动载荷，还需要精心选择每个结构参数的值，以改善轴承零件接触应力分布，达到有利于润滑油膜形成的接触状态，提高轴承的使用寿命。
2、套圈沟道位置
工业机器人的接触球轴承内、外圈采用整体结构，而且一般截面积只有相同内径标准轴承20％，所以就造成了保持架的径向壁厚取值很有限，如果把沟道位置设计在轴承宽度的中心，这样轴承就成了对称结构，同时保持架兜孔底部强度和密封圈的安装位置就将受到限制。因此，为保证轴承保持架具有足够的强度和密封圈有足够的安装空间，沟位置采取对两侧端面不对称的设计。
3、挡边高度的确定
工业机器人的接触球轴承处于工作状态时，在承受一定的径向载荷时，同时还要承受一定的轴向载荷。若承受的轴向载荷过大，可能造成钢球与内、外圈挡边边缘接触或挡边与滚道之间的接触椭圆被截断，这时候就会产生应力集中，轴承套圈就会受到磨损，从而影响精度。
因此，挡边高设计时，需根据轴承承受轴向载荷大小利用Hertz接触应力理论推算出轴承套圈小挡边高度J，从而计算出套圈挡边直径。而在设计时考虑到接触球轴承截面积较小，在满足使用要求前提下，挡边高系数取值可以比深沟球轴承小。
4、密封结构设计
工业机器人的轴承的早起破坏一般是因为密封性不好，因为密封性不好，空气中的杂物或者其他污染物就容易进入轴承，从而使润滑脂逐渐失效，导致轴承损坏。所以轴承的密封性很关键。因此设计密封轴承时，既要考虑到密封，同时要考虑到轴承的具体工作要求和轴承的具体结构形式。
工业机器人正在朝小型化、轻量化、精密化发展。因此工业机器人用轴承的润滑采用带密封结构的润滑方式进行脂润滑。
5、针对工业机器人轴承壁薄的特点
轴承内圈与密封唇的配合方式一般有两种：
(1)内圈密封唇与内圈挡边接触的接触式密封
(2)内圈密封唇与内圈挡边接触的非接触式密封
接触式密封相对于非接触式密封防尘漏脂效果要好，但其摩擦力矩较大，温升较高，考虑到摩擦力矩较大，对机器人主机有不利影响，设计时一般采用非接触式密封结构。
另外由于轴承套圈壁很薄，轴承内、外圈易变形，所以内圈挡边可采用无槽结构，但要严格控制密封间隙。
(大国龙腾运转世界 龙出东方 腾达天下 龙腾三类调心滚子轴承 刘兴邦 )
The Relationship between Precision of Industrial Robots and Bearing Design
Industrial robots are a new type of high-tech intelligent machine equipment that can replace some manual labor in industrial production. As an industrial robot, its requirements can be described in three words: fast, accurate, and stable.
For current robot production technology, both fast and accurate are easier to achieve, but it is relatively difficult to achieve accuracy while achieving speed and stability.
Here is a definition of the term: repetitive positioning accuracy of industrial robots - industrial robots repeat a certain action (usually 10-20 times), and the average deviation from the planned position each time is its repetitive positioning accuracy, which is generally measured using a laser interferometer.
For industrial robots, accuracy is a crucial factor that directly affects the quality and production efficiency of products. The main factor affecting the accuracy of industrial robots is bearings. So what kind of bearings can make industrial robots have higher accuracy?
1. Key structural parameter design
The bearings of industrial robots have the requirements of long life, high rigidity, and low friction. Therefore, when designing industrial robots, it is not only necessary to consider the maximum rated dynamic load, but also to carefully select the values of each structural parameter to improve the contact stress distribution of bearing parts, achieve a contact state that is conducive to the formation of lubricating oil film, and improve the service life of bearings.
2. Ring groove position
The inner and outer rings of the contact ball bearings of industrial robots adopt an integral structure, and the general cross-sectional area is only 20% of the standard bearing with the same inner diameter. Therefore, the radial wall thickness of the cage is limited. If the groove position is designed at the center of the bearing width, the bearing becomes a symmetrical structure. At the same time, the strength of the bottom of the cage pocket hole and the installation position of the sealing ring will be limited. Therefore, in order to ensure that the bearing cage has sufficient strength and the sealing ring has sufficient installation space, the groove position is designed to be asymmetrical on both sides of the end face.
3. Determination of edge height
When the contact ball bearing of industrial robots is in working condition, it also needs to withstand a certain axial load while bearing a certain radial load. If the axial load borne is too large, it may cause the contact ellipse between the steel ball and the inner and outer ring edges, or between the edges and the raceway, to be truncated. At this time, stress concentration will occur, and the bearing ring will be worn, thereby affecting accuracy.
Therefore, when designing the height of the retaining edge, it is necessary to use Hertz contact stress theory to calculate the height J of the small retaining edge of the bearing ring based on the axial load borne by the bearing, and thus calculate the diameter of the retaining edge of the ring. When designing, considering the small cross-sectional area of the contact ball bearing, the value of the rib height coefficient can be smaller than that of the deep groove ball bearing, provided that it meets the usage requirements.
4. Sealing structure design
The early failure of bearings in industrial robots is generally due to poor sealing. Due to poor sealing, debris or other pollutants in the air can easily enter the bearings, causing the lubricating grease to gradually fail and leading to bearing damage. So the sealing of bearings is crucial. Therefore, when designing sealed bearings, it is necessary to consider both sealing and the specific working requirements and structural form of the bearings.
Industrial robots are developing towards miniaturization, lightweight, and precision. Therefore, the lubrication of bearings for industrial robots adopts a lubrication method with a sealed structure for grease lubrication.
5. Targeting the characteristics of thin bearing walls in industrial robots
There are generally two ways to fit the inner ring of the bearing with the sealing lip:
(1) Contact sealing between inner ring sealing lip and inner ring retaining edge
(2) Non contact sealing between inner ring sealing lip and inner ring retaining edge
Compared to non-contact sealing, contact sealing has better dustproof and grease leakage effects, but its friction torque is larger and the temperature rise is higher. Considering that the friction torque is larger and has adverse effects on the robot host, non-contact sealing structures are generally used in the design.
In addition, due to the thin wall of the bearing sleeve, the inner and outer rings of the bearing are prone to deformation. Therefore, a slotless structure can be used for the inner ring edge guard, but the sealing clearance must be strictly controlled.
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