Multivariate time series dataset of milling 16MnCr5 for anomaly detection

The dataset consists of seven folders. Each folder represents one milling run. In each milling run the depth of cut was set to 3 mm. A folder contains a maximum of three json files. The number of files depends on the time needed for each run which is a function of milling tool diameter and feed rate. Files in each folder were numerated in sequence. For example, folder “run1” contains the files “run1_1” and “run1_2” with the last number indicating the order in which the files were generated. The frequency of recording datapoints was set to 500 Hz. During each milling run the milling tool moved along the longitudinal side and then was moved back alongside the workpiece. This way machining started always on the same side of the workpiece. Table 1 provides an overview of the milling runs. Run 1 to 4 were performed with a HSS tool with a diameter of 10 mm. The tool in use was an end mill (HSS-E-SPM HPC 10 mm) developed by Hoffmann Group. During the first three runs with this end mill no tool breakage occurred. However, in run 4 the tool broke. Runs 5 and 6 were performed by milling with an end mill of the same tool series (HSS-E-SPM HPC 8 mm) that just differs in tool diameter. In contrast to this run 7 was performed by using a solid carbid tool (Solid carbide roughing end mill HPC 8 mm). Cutting with SC tools provides much higher productivity with the downside being higher tool price. In our case the SC end mill performed cuts with a feed rate of 1150 mm/min compared to 191 mm/min achieved by a HSS end mill of the same diameter. Tool breakages were recorded on all runs with end mills of diameter 8 mm. Table 1. overview of the data folders folder name | number of json files | tool diameter | tool breakage | tool type run 1 2 10 mm No HSS run 2 2 10 mm No HSS run 3 2 10 mm No HSS run 4 2 10 mm Yes HSS run 5 2 8 mm Yes HSS run 6 3 8 mm Yes HSS run 7 1 8 mm Yes SC Each json file consists of a header and a payload. The header lists all parameters that were recorded such as position, motor torque and motor current of each of a maximum of five axes of a milling machine. However, the machine used in our experiments is a 3-axis machining center which leaves the payload of 2 possible additional axes to be empty. In the payload the sequential data for each parameter can be found. A list of recorded signals can be found in Table 2. Table 2. recorded signals during milling Signal index in payload | Signal name | Signal Address |Type 13-18 VelocityFeedForward VEL_FFW|1* double 19-24 Power POWER|1* string 25-30 CountourDeviation CONT_DEV|1* double 38-43 TorqueFeedForward TORQUE_FFW|1* double 44-49 Encoder1Position ENC1_POS|1* double 56-61 Load LOAD|1* double 68-73 Torque TORQUE|1* double 68-91 Current CURRENT|1* double * 1 represents x-axis, 2 represents y-axis, 3 represents z-axis and 6 represents spindle-axis. Note that our milling center has 3 axis and therefore values for axes 4 and 5 are null.

本数据集共包含7个文件夹，每个文件夹对应一次铣削加工运行。每次运行的切削深度均设置为3mm。每个文件夹最多包含3个JSON文件，文件数量取决于单次运行的耗时，而耗时是铣刀直径与进给率的函数。文件夹内的文件按生成顺序依次编号，例如“run1”文件夹包含“run1_1”与“run1_2”两个文件，末尾数字代表文件生成次序。数据采集频率设置为500Hz。

每次铣削运行中，铣刀先沿工件纵向侧边移动，随后沿工件回程，加工始终从工件的同一侧开始。表1为各铣削运行的概况。运行1至4采用直径10mm的高速钢（High Speed Steel, HSS）刀具，具体为霍夫曼集团（Hoffmann Group）研发的端铣刀（HSS-E-SPM HPC 10 mm）。使用该端铣刀的前三次运行均未发生刀具破损，但运行4出现了刀具断裂。运行5与6采用同系列端铣刀（HSS-E-SPM HPC 8 mm），仅刀具直径不同。与之不同的是，运行7使用了整体硬质合金（Solid Carbide, SC）刀具（Solid carbide roughing end mill HPC 8 mm）。采用SC刀具可获得更高的加工效率，但刀具成本也更高。本实验中，SC端铣刀的进给率为1150 mm/min，而同直径HSS端铣刀的进给率仅为191 mm/min。所有使用8mm直径端铣刀的运行均出现了刀具破损。

表1 数据文件夹概况
文件夹名称 | JSON文件数量 | 刀具直径 | 刀具破损情况 | 刀具类型
run1 | 2 | 10 mm | 否 | HSS
run2 | 2 | 10 mm | 否 | HSS
run3 | 2 | 10 mm | 否 | HSS
run4 | 2 | 10 mm | 是 | HSS
run5 | 2 | 8 mm | 是 | HSS
run6 | 3 | 8 mm | 是 | HSS
run7 | 1 | 8 mm | 是 | SC

每个JSON文件均由文件头（header）与数据负载（payload）组成。文件头列出了所有采集的参数，包括铣床最多5个轴的位置、电机扭矩与电机电流等。但本实验所用设备为3轴加工中心，因此额外2个轴的负载数据均为空。数据负载中包含各参数的时序数据，采集的信号列表详见表2。

表2 铣削过程采集信号
payload内信号索引 | 信号名称 | 信号地址 | 数据类型
13-18 | 进给前馈速度（VelocityFeedForward, VEL_FFW） | 1* | 双精度浮点型
19-24 | 功率（POWER） | 1* | 字符串型
25-30 | 轮廓偏差（CountourDeviation, CONT_DEV） | 1* | 双精度浮点型
38-43 | 扭矩前馈（TorqueFeedForward, TORQUE_FFW） | 1* | 双精度浮点型
44-49 | 编码器1位置（Encoder1Position, ENC1_POS） | 1* | 双精度浮点型
56-61 | 负载（LOAD） | 1* | 双精度浮点型
68-73 | 扭矩（TORQUE） | 1* | 双精度浮点型
68-91 | 电流（CURRENT） | 1* | 双精度浮点型
*注：1代表X轴，2代表Y轴，3代表Z轴，6代表主轴轴。本铣床加工中心仅为3轴设备，因此轴4与轴5的采集值均为0。