At present, machining with numerically controlled (NC) machine tools is mostly performed by NC programs generated by computer-aided design and computer-aided manufacturing (CAD/CAM) systems. However, ...even if the machining shape to be machined is the same, there are numerous machining processes involving a series of operations such as determining the machining area, machining order, and machining conditions. These are entrusted to the user, and automation is difficult. In addition, these tasks depend on the experience and know-how of skilled engineers, and it is very difficult to convert them into algorithms and reflect them in the creation of NC programs. Therefore, in this study, artificial intelligence (AI) was used for the process design of multi-tasking machine tools, with the goal of determining and automating the process design using shape examples. We propose a shape recognition method that includes image analysis by AI. This image analysis makes it possible to determine the characteristics of the machining shape, and the machining operator can easily judge the machining process based on the CAD model. Furthermore, because there are shapes that cannot be determined from image data alone, shape features are also extracted from the STEP file of the CAD model. A language analysis of the STEP file can find the characteristic components and their numerical information to determine the coordinates of the shape features. By combining image analysis and language analysis, the method can easily judge the process based on the information in the CAD model. Finally, using the generated learning model and analysis program, we conducted a test to determine whether a multitasking machine tool is necessary for machining.
Chatter vibration is a major problem in machining. At present, chatter vibration is avoided by changing the cutting conditions based on the stability limit diagram such that chatter vibration does ...not occur. However, changing the cutting conditions may reduce the productivity. The stability limit is estimated from the relationship between the dynamic characteristics of the machine tool and the cutting conditions. Therefore, we propose a method for avoiding chatter vibration by changing the machine tool rigidity. The dynamic characteristics of a desktop milling machine tool developed in a previous study can be changed by changing the tensile load of the brace bar attached on the frame. We report the transition of the dynamic characteristics and stability limit diagram with changes in the rigidity of the desktop machine tool, and confirm the presence or absence of chatter vibration through machining tests.
Development of a machine tool simulator based on VR ONODERA, Shuma; HAYASHI, Akio; MORIMOTO, Yoshitaka
Journal of Advanced Mechanical Design, Systems, and Manufacturing,
01/2022, Volume:
16, Issue:
5
Journal Article
Peer reviewed
Open access
In the manufacturing industry, various types of machine tools are widely used by many engineers. Some inexperienced users of machine tools, such as students and trainees, operate machine tools when ...they are training to acquire skills. However, machine tools have mechanisms that rotate at high speed and exert large forces, which can be dangerous for inexperienced users, and therefore safe training of personnel is required. Virtual reality (VR) is inexpensive compared to machine tools and can provide an immersive training environment for a large number of personnel. In this study, we developed a training system for machining training in a virtual space for a desktop milling machine tool. Based on the input NC program, the movement of each axis and the rotation of the main axis are represented, associated with the control panel by C# script. As a training function, interference between the tool and workpiece, hand contact with the tool, and overrun of each axis are determined by interference checks for each part, and an interface is created that displays warnings on the user's line of sight. In addition, the machined shape is reproduced by using a function called “stencil” in Unity. Furthermore, in order to realize the digital twin, the behavior of the actual machine and that of the virtual machine can be synchronized using TCP/IP, and the behavior of the table of the actual machine tool can be monitored.
Microbiota alteration and IFN-γ-producing CD4+ T cell overactivation are implicated in Crohn's disease (CD) pathogenesis. However, it remains unclear how dysbiosis enhances Th1 responses, leading to ...intestinal inflammation. Here, we identified key metabolites derived from dysbiotic microbiota that induce enhanced Th1 responses and exaggerate colitis in mouse models. Patients with CD showed elevated lysophosphatidylserine (LysoPS) concentration in their feces, accompanied by a higher relative abundance of microbiota possessing a gene encoding the phospholipid-hydrolyzing enzyme phospholipase A. LysoPS induced metabolic reprogramming, thereby eliciting aberrant effector responses in both human and mouse IFN-γ-producing CD4+ T cells. Administration of LysoPS into two mouse colitis models promoted large intestinal inflammation. LysoPS-induced aggravation of colitis was impaired in mice lacking P2ry10 and P2ry10b, and their CD4+ T cells were hyporesponsive to LysoPS. Thus, our findings elaborate on the mechanism by which metabolites elevated in patients with CD harboring dysbiotic microbiota promote Th1-mediated intestinal pathology.
Recently, measures to address environmental problems and resource problems have been strongly desired. Consequently, the energy saving of machine tools has been promoted at production sites. Thus, ...the efficiencies of motors and coolants have been improved for the energy saving of machine tools. However, replacing machines and peripherals is time-consuming and expensive. Therefore, we focused on the power consumption by the feed drive system and spindle of a machine tool during machining. Considering of the energy conservation in the feed drive system and spindle is practical and effective to existing machine tools. In this study, we propose the simulator that calculates the energy consumption of the feed drive system and spindle using the NC program. It is possible to calculate the energy consumption without actual machining and measuring. Using the simulation result, we can change the tool path and machining conditions, leading to a reduction in machining power consumption. This study devised a method for calculating the power consumption of the feed drive system using the NC program using only the reference power consumption of the machine tool. Then, the measured and simulated power consumptions for machining were compared to verify the validity of the proposed method.
Parallel mechanisms with multiple links have been expected to be used in machining because they are higher in rigidity, accuracy, and output power than series mechanisms, such as industrial robots. ...However, unlike conventional machine tools, which consist of linear and rotary axes, parallel mechanisms have a large number of error factors. In the parallel link mechanism, there is no guide surface that physically guarantees linearity, and all accuracy is determined by the operating performance of the composite axes. This makes it difficult to identify any error factors. Therefore, a kinematics model is devised, and the behavior of the tool tip is checked by inputting the encoder information during the actual operation of a specific axis. Based on the results, we evaluate the machining characteristics of the target machine tool. The target machine tool in this study is a 5-axis machine tool that combines a 3-DOF parallel mechanism consisting of three linear motion axes and a 2-DOF serial mechanism consisting of two rotary axes. In our previous research, we tried to build a forward kinematics model. Although its prediction accuracy was insufficient, it was possible to actually identify the cause of the defect in the quality of the machined surface using the servo position information of the kinematics machine. However, we have not been able to construct an inverse kinematics model that is suitable for calculating the correction position command value to improve the quality of the machined surface. In this study, based on the shape creation theory, we devise and evaluate the kinematics model of a robotic machine tool that has a parallel mechanism. As a result of comparing the kinematics model with the 3D-CAD model in order to evaluate the accuracy of the former, it was confirmed that the proposed method has high simulation accuracy. Then, machining tests were carried out to evaluate the machining accuracy by measuring, based on proposed kinematics model, the machined surfaces in order to identify the mechanism that affects the texture of the machined surface. In addition, we performed a circle interpolation to confirm the effects of reversing the motion of each drive axis on the behavior of the tool tip. As a result, it is considered that the linear motion axis has a large effect on the behavior of the tool tip on the quadrant glitch of each drive axis. It was also found that the effects of the 1st- and 3rd-axes on the behavior of the tool tip are different from those of the 2nd-axis.
This study aimed to compare the results of the Chronos binocular/monocular refraction system, that measures objective and subjective ocular refraction in one unit, to objective findings obtained from ...a conventional autorefractometer and a conventional subjective ocular refraction using a trial-frame in real space.
Twenty-eight healthy volunteers (21.2 ± 1.5 years old) were included in this study. Objective ocular refraction was measured using two tests: the Chronos binocular/monocular refraction system under binocular conditions and a conventional autorefractometer under monocular conditions. Subjective ocular refraction was measured using three tests: Chronos binocular/monocular refraction system under binocular, monocular conditions, and trial-frame in the real space under monocular conditions. The measurement distance was set to 5.0 m for each test. All ocular refractions were converted into spherical equivalents (SEs).
The objective SE was significantly more negative with Chronos binocular/monocular refraction system under binocular condition (- 4.08 ± 2.76 D) than with the conventional autorefractometer under monocular condition (- 3.85 ± 2.66 D) (P = 0.002). Although, the subjective SE was significantly more negative with Chronos binocular/monocular refraction system under binocular condition (- 3.55 ± 2.67 D) than with the trial-frame in the real space under monocular condition (- 3.33 ± 2.75 D) (P = 0.002), Chronos binocular/monocular refraction system under monocular condition (- 3.17 ± 2.57 D) was not significantly different from that in trial-frame in real space under monocular condition (P = 0.33).
These findings suggest that the Chronos binocular/monocular refraction system, which can complete both objective and subjective ocular refraction tests in a single unit, is suitable for screening ocular refraction, although it produces slightly more myopic results. Furthermore, subjective ocular refraction testing accuracy in Chronos binocular/monocular refraction system can be equivalent to trial-frame in real-space testing by switching from binocular to monocular condition.
A machining center is a common machine tool that can machine complex free-form surfaces such as the press mold, automobile’s cam profile. When these curved surfaces are machined by the conventional ...machining center and/or the grinding machine, it takes lot of time to complete with enough accuracy. In order to solve this problem, this study aims not only to improve the machining accuracy of this curved surface but also to make it possible to shorten the machining time using a CNC lathe. In this study, the NACS-Turning (Non-axisymmetric curved surface turning) method that we proposed originally was used. The spindle of C-Axis, the moving table with the cutting tool of X1-Axis, the other counter moving table of X2-Axis (without involved in shape creation, only used to suppress inertial force), the head stock of Z-Axis, and the tool rotation axis of B-Axis are adapted. In this 4-Axis machining method, all the axes are controlled with the synchronized manner. This method can machine the same rotational position of workpiece with the same cutting edge of the rotary tool. As an experiment, we compared 4-Axis machining with synchronized spindle and tool rotation, 3-Axis machining, and machining without synchronous rotation. Our new 4-Axis machining method with synchronized spindle and tool rotation reduced the form error from 323 ㎛ to 247 ㎛ and the surface roughness from Rz 9.6μm to Rz 3.7μm. Moreover, the repetitive machining resulted in error of 99.6μm and a surface roughness of Rz2.9μm.
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