Hardness Testing of Automotive Crank Pins and Journals

This article presents a case study where automation saved a significant amount of operators’ time when making and measuring indents in three specified locations of automotive crank pins and journals, compared to manual testing.

自动化方法转化为较少的数据转录错误，零件操作较少以及进行测试的操作员之间的可变性较低。

Hardness Testing of Automotive Crank Pins and Journals

一家主要的汽车制造商试图研究自动化如何在汽车曲柄销和期刊硬度测试期间节省潜在的时间。在目前的过程中，每次班次都需要两个熟练的操作员，每天有两个班次，每周七天。

Tests are carried out in three given locations - one perpendicular to axis and two at 45° off axis. The given locations are critical, because if the locations are missed the manufactured parts are likely to be quarantined until the part information can be further validated.

另一个主要问题是，未意外通过安装的失败零件最终会导致灾难性的失败。数据转录中的错误是另一个关注的根源。如果零件信息未正确馈送到单个数据库中，则可能会发生不匹配的数据，这最终会导致零件的扩展隔离，直到可以进行进一步的确认为止。

The overall scrap cost is a significant factor and hence, trained operators are required for testing purposes. Operator variability is determined with round robin testing. Compared to the usual operation analysis rate, the testing rate increased by as much three to five times when qualifying new lines were put into production.

观察

当前的过程观察

为了确定现有过程的时间基准，随后建立了对汽车曲柄引脚和期刊的Vickers缩进的时间评估。目前的测试程序中使用了独立的手动系统，以及操作员的时间来使部分对齐以及制作和测量凹痕。

然后将零件以相似的方向固定，以确保45°轴的测量保持接近速度测试并减少测试误差。在物理测试之前，应对准零件对齐，以确保高度准确性。

It was seen that the most testing time (60%) was taken up by the operators’ set up time for indent locations, with the measuring indents and making indents taking the second and third largest amounts of testing time at 30% and 10%, respectively.

While the overall amount of indents of each pin and journal differed, 18 indents were averaged for each section, with 6 in each location. The overall amount of indents for a crankshaft; journals being determined along split; and pins being determined bottom dead center and top dead center, was averaged to 216 indents. Nine hours with eight hours of operator interaction made up the overall analysis time to make and measure indents at the given locations on a crank.

实施过程

AWilson VH3100系列Vickers Microhardness测试仪与直径软件集成在一起用于实施过程。将零件固定在机械师的恶习上，然后将其加载到舞台上，而无需操纵方向（图1）。

Figure 1.Crank pin held in machinist vice

图片来源：Buehler

为了产生要测试的零件的模板，与概述摄像机一起使用跟踪功能（图2）。这减少了缩进位置所需的设置时间。该模板将位置设置时间缩短到这三个区域的45秒 - 一个垂直于案例，两个在45º处。

Figure 2.痕量功能模板，以便于缩进位置

图片来源：Buehler

直径软件捕获了给定位置的零件的模板，该位置已由操作员确认。观察设置时间为10％；缩进为50％；测量压痕为40％。216凹痕平均是曲轴的缩进总量，在15分钟的操作员交互作用中需要1.25小时。图3显示了凹痕的自动制作和测量。

Figure 3.Indent make and measure being performed automatically

图片来源：Buehler

对于每个程序，引入了视觉低和高阈值警告（图4）。这使操作员能够在分析所有曲柄引脚和期刊之后，快速评估零件，如较早的方法中所做的那样。为了报告目的，设置了元数据以消除数据转录中的操作员错误（图5）。

图4。Visual high low threshold warnings to alert operators of hardness thresholds

图片来源：Buehler

图5。Metadata setup to reduce operator input transcription errors

图片来源：Buehler

结论

The study shows how automation saves considerable amounts of time with regard to setup and also the time needed for making and measuring the Vickers indents. The overall amount of time spent by the operators for setting the indent profile and measuring and collating the data is reduced by as much as 86%, including the data transcribing errors.

Testing repeatability is increased from one operator to another, because inconsistency between operator judgment is completely removed. The use of trace function and templates removed operator time required for aligning parts on the stage and also reduced the risk of a lost indent profile.

The increased visibility of part failure is apparent during the measurement and allows operators to reassess an area or the entire part without the need for extended quarantine of parts for reanalysis. Data transcribing issues were eliminated using metadata fields within the维克斯测试程序which would otherwise delay crank batches until further review of the records.

This information has been sourced, reviewed and adapted from materials provided by Buehler.

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