News Center
According to the three-tuple model of HCPS that is proposed in Ref. [14], the machine tool is the ‘‘subject,” the NC is the ‘‘commander,” and the human is the ‘‘dominator” in NC machining practice. From the MOMT to the NCMT, and eventually to the IMT, the most significant change lies in the continuous increased functions of the NC. The degree of intellectualization of the machine tool is determined by the level of intellectualization of the NC. Before building an IMT, a corresponding INC is necessary.
4.1. The intelligent numerical controller
In this research, an INC (the HNC-9) was developed; its architecture is schematically shown in Fig. 6. The Local NC, which is the physical entity of the INC, is composed of the NC device, servo drive, motor, and other auxiliary devices, and is used to complete the real-time control of the IMT.
Fig. 6. System architecture of the INC. AGV: automated guided vehicle.
In addition to all the functions of a traditional NC, the INC must have the basic sensing ability for its intellectualization, which is to collect and transfer the internal electronic data (e.g., the instruction data and response data) as well as some external data from the sensors (e.g., temperature, video, and vibration) of the controlling process in real time.
By using the NCUC2.0 field bus, the INC retrieves data from multiple sources, such as the servo drive, intelligent module, and external sensors. By utilizing the NC-LINK interconnection protocol, machine tools, industrial robots, automated guided vehicles (AGVs), and intelligent modules are connected, while the big data is aggregated and stored on the big data platform called the INCCloud. The INC-Cloud can provide several useful tools for data management and knowledge generation, such as algorithm and match libraries, databases, and deep leaning platforms.
The main characteristics of the INC are a response-level digital twin and the corresponding intelligent functions (i.e., Apps). In the INC, the Cyber MT and the Cyber NC are built; these are respectively the digital twins of the physical machine tool and of the Local (physical) NC. The digital twins can simulate the working principle and responding rule of the machine tool and the NC in cyberspace. As the integration of the physical space (i.e., Local NC) with the cyberspace (i.e., Cyber MT and Cyber NC), the INC is the foundation for the intelligence of the IMT.
4.2. Industrial prototypes of the IMT
Based on the proposed INC, we developed three industrial prototypes of the IMT—namely, the S5H precision machine tool, the BL5-C intelligent lathe machine, and the BM8-H intelligent milling machine (Fig. 7). These three IMTs were utilized to verify the three intelligent enabling technologies proposed in this paper.
Fig. 7. Industrial prototypes of IMTs based on the INC. (a) The S5H precision machine tool; (b) the BL5-C intelligent lathe machine; (c) the BM8-H intelligent milling machine.
The S5H precision machine tool was constructed by taking a precision machine tool as the main body. It has the following characteristics: It is composed of a marble bed with each feeding axis equipped with a high-precision grating ruler and driven by a linear motor; three independent control systems are used to separately control the temperature of the spindle, bed, and coolant; 18 temperature sensors are embedded in the body of the machine tool; and three vibration sensors are installed at the front-end bearings of the spindle and the working table. The positioning accuracy of the machine tool is ≤1 μm, while the repeated positioning accuracy is ≤0.5 μm. This machine tool is utilized to verify Intelligent Function 1: Surface machining quality optimization based on Cyber NC and double-code control technology, which will be presented in Section 4.3.
The BL5-C intelligent lathe machine was constructed by taking a slant bed lathe machine as its main body. It has the following characteristics: Temperature sensors are installed to detect the temperature of the machine tools at different locations, such as at the X and Z feeding axes (at the bearing seat and nut seat), spindle (at the bearing seat), body of the machine tool, and so on; vibration sensors are installed on the spindle box to detect the vibration frequency; grating rulers are installed on the X and Z feeding axes as position inspection devices of their closed-loop control. The positioning accuracy of the machine tool is ≤6 μm, the repeated positioning accuracy is ≤3 μm, and the roundness of the turning parts is ≤2 μm. This machine tool is utilized to verify Intelligent Function 2: Machining parameters optimization of lathing based on big data modeling, which will be presented in Section 4.3.
The BM8-H intelligent milling machine has in total nine temperature sensors embedded at the ball screw, bearing seat, and motor seat of three feed axes, and four temperature sensors on the spindle box. These sensors are used to monitor the temperature in order to model the thermal deformation of the machine tool. A threedirectional vibration sensor is installed on the spindle and working table, and a high-precision grating ruler is installed on each feeding axis for closed-loop control. The positioning accuracy of the machine is ≤10 μm and the repeated positioning accuracy is ≤8 μm. This machine tool is used to verify Intelligent Function 3: Hybrid modeling of the machine tool’s feeding system and its application to contour error compensation, which will be presented in Section
THK SVR65R1UU SVS65R1QZKKHH
SRG20XV SHS30LV1KKHH
SVR65C4QZTTHHC0+10700LPT-III
SVR65R4QZTTHHC0+4640LPT-II
SHS30LV1QZKKC1
HRW35CA2UU+3300LT
HRW21CA2UUC1+200L
HRW21CA2UUC1+250L
SHW12CR1UUC1M+670LM
2HR2042UU+280L
2HR2555TUU+600L
2HR3065UU+600L
THK HSR20R2SSEM+240LM
SRG25R1QZSS+440LP
SRG25C1SS+360LP
SHS55C2QZSSC0F+1020LPF
SRG55C2SSCIE+1500LP-II
SRG55C2SSC1E+1620LP-II
SRG35C2SSC1E+680LP-II
SRG55C2SSCIE+1500LP-II
