洛氏硬度计虽然结构简单，操作方便，但如果长时间操作不当，测试硬度会不准确，极大地影响产品质量，带来不良后果。 下面我们就来介绍一下验证中的几种常见错误及处理方法
1. 人为错误。
（1）操作人员技术水平不够，实践经验差，应由熟悉硬度计的人员使用； (2)加载太快，加载保持时间短，低硬度零件硬度高，加载太慢，加载保持时间长，硬度低。 运行时装料应平整，并保持一定的装料时间。
2、影响被测零件的因素。
(1)不同的表面光洁度对洛氏硬度试验的影响不同。 表面光洁度越低，高硬度试验的硬度就越高，反之，硬度越低，有刀痕的粗糙表面，淬火时冷却最快，或者很硬的表面，硬度值就越高。 反之，调质件在高温回火时，带刀痕的表面组织首先发生转变，抗回火能力小，硬度值低。 测试表面光洁度在△7以下的零件时，必须用废砂轮进行精磨，然后用锉刀锉平，或用细手砂轮打磨，然后擦干净。
(2)热处理件表面有盐渍、砂粒等。 当负载增加时，零件会滑动。 如果有油腻，金刚头在压入时会润滑，减少摩擦，增加压入深度。 这两个原因使得测得的硬度值偏低。 被测零件的薄氧化皮层和植物松层的硬度值降低，而厚氧化皮层的硬度值增加。 待测硬度的零件，必须去除氧化皮，擦拭干净，不得有污垢。
（3）倾斜（或锥度）、球面和圆柱形零件的硬度测试误差比平面要大。 当压头压入此类零件表面时，压痕处周围阻力小于平面，甚至出现跑偏、打滑现象，压痕深度增加，硬度降低。 曲率半径越小，斜率越大，硬度值下降越明显。 金刚石压头也容易损坏。 对于此类零件，应设计专用工作台，使工作台与压头同心。
三是压头的影响。
(1)金刚石压头不符合技术要求或使用一段时间后磨损。 如果操作者无法判断钻石的质量，可以通过计量检测机构进行验证。
(2)钢球压头强度和硬度不够，容易变形。 当钢球被压扁并产生永久变形时，它就变成了一个椭圆。 短轴与零件表面垂直时，压痕浅，示值高； 当长轴垂直于零件表面时，压痕加深，示值减小，钢球公差小0.002mma
第四，负载。
(1)初荷：弹簧与主轴、杠杆与百分表之间有摩擦，产生100N的增减。 调整螺钉松动，调整块移动，顶杆位置不当。 起跑线不同，导致初始加载不正确。 如果初始载荷不正确，应调整弹簧、主轴、杠杆、百分表等的配合。 调整块位置移动正常后，拧紧调整螺钉，同时拧紧顶杆位置。 初始负载的公差应小于±2%。
（2主载荷；如果第二个杠杆比例正确，则拉杆配重和重物有误差；如果主轴、杠杆和重物歪斜，会导致主 鱼负荷。杠杆比不正确，应调整，刀口磨损，应修理或更换，并矫正主轴变形。主轴偏斜， 应校正杠杆和重量，各种秤的主要载荷之差小于0.5%。
5、硬度计放置不当。
硬度计不在水平位置，测试硬度时其数值偏低。 使用水平仪测量水平度，然后将硬度计压平。
6、零件某试验件表面与工作台接触不良，或支撑点不稳定：
这会导致打滑、滚动、翘曲等，不仅会使结果不准确，还会损坏仪器。 应根据零件的几何形状设计合适的工作台。
10、周围环境的影响。
工厂生产中使用的硬度计经常会因周围环境而受到振动的影响，导致仪器结构松动，显示值不稳定。 硬度计应安装在无振动或远离振动源的地方。
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Although rockwell hardness tester is simple in structure and easy to operate, if it is operated improperly for a long time, the quality of products will be greatly affected, resulting in adverse consequences. Now we are in the verification of several common errors and processing methods are introduced as follows
First, human error.
(1) Operators are not skilled enough and have poor practical experience, so they should be used by those familiar with the hardness tester; (2) charging too fast, holding time is short, the hardness of parts with low hardness is high, and the loading is too slow, holding time is long, and the hardness is low. The loading should be smooth during operation, and the loading time should be maintained.
Second, the factors affecting the measured parts.
(1) Different surface finish in rockwell hardness test, show different effects. The lower the surface finish, the higher the hardness of the high hardness test, on the contrary, the lower the hardness, the rough surface with knife marks, the first fastest cooling when quenching, or very hard surface, the hardness value is high. On the contrary, when tempering parts at high temperature, the surface tissue with knife marks changes first, and the ability to resist tempering is small, and the hardness value is low. When testing parts with a surface finish below △7, it is necessary to use a waste grinding wheel for fine grinding and then smooth them with a file or smooth them with a fine hand grinding wheel and wipe them clean.
(2) The surface of heat treatment parts with salt, sand and other things, when loading, parts will slip, if there is grease, diamond head pressure when the lubrication effect, reduce friction, increase the pressure depth. These two reasons cause the measured hardness value to be low. The hardness value of the thin oxide peel pine layer decreases and the hardness value of the thick oxide peel dense layer increases. To measure the hardness of the parts must remove the oxide skin, wipe clean, no dirt.
(3) The incline (or taper), spherical and cylindrical parts of the hardness test error is larger than the plane. When the pressure head is pressed into the surface of this part, the resistance around the pressure is smaller than the plane, and there is even deviation and slippage, and the depth of the pressure increases, and the hardness decreases. The smaller the radius of curvature is, the larger the slope is, the more significant the hardness value decreases. Diamond indenter is also vulnerable to damage. To this kind of parts to design a special table, so that the table and pressure head concentric.
Three, the impact of the head.
(1) The diamond indenter does not meet the technical requirements or is worn after a period of use. If the operator cannot judge the quality of the diamond, it can be verified by the metrological testing institution.
(2) Steel ball head strength and hardness is not enough, easy to produce deformation. The steel ball is elliptical after the permanent deformation caused by flattening. When the short axis is perpendicular to the surface of the parts, the indentation is shallow and the value is high. When the long axis is perpendicular to the surface of the parts, the indentation deepens, the indication value decreases, and the ball tolerance is 0.002mmA smaller
Four, load.
(1) Initial load: spring and spindle, lever and dial indicator. There is friction between them, causing 100N to go up or down. The adjusting screw is loose, the adjusting block moves, and the push rod position is improper. The starting line is different, resulting in incorrect initial load. If the initial load is not correct, should adjust the spring, spindle, lever, dial indicator, etc. Tighten the adjusting screw and push rod after the adjusting block is moved properly. The allowance of initial load should be less than 2%.
(2 main load; Two lever proportion is not correct, product bar and weight balance error; Deflection of spindle, lever and weight can cause errors in the main fish load. If the rod ratio is not correct, it should be adjusted. Knife-edge wear should be repaired or replaced, and spindle deformation should be straightened. Spindle, lever and weight deflection should be adjusted. The modal difference of the main load of all scales is less than 0.5% of soil.
Five, hardness tester placement is not straight.
The hardness tester is not in a horizontal position and its value is low when testing hardness. Measure the levelness with a level, then line a level hardness tester.
Six, parts of a test part of the surface and the table is not good contact, or the support point is not stable: industry
This will cause slippage, rolling, warping and other phenomena, which will not only make the results not accurate but also damage the instrument. A suitable worktable shall be designed according to the geometry of the parts.
10. The influence of the surrounding environment.
The hardness tester used in factory production is often affected by the vibration of the surrounding environment, resulting in loose instrument structure and unstable display value. The durometer should be installed in a place without vibration or far from the source.
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