scholarly journals Design and Evaluation of Uniform LED Illumination Based on Double Linear Fresnel Lenses

2020 ◽  
Vol 10 (9) ◽  
pp. 3257
Author(s):  
Hoang Vu ◽  
Ngoc Minh Kieu ◽  
Do Thi Gam ◽  
Seoyong Shin ◽  
Tran Quoc Tien ◽  
...  
Keyword(s):  
High Speed ◽  
Field Experiments ◽  
Numerical Control ◽  
Free Form ◽  
Light Sources ◽  
Cnc Machine ◽  
Led Lighting ◽  
Positive Effects ◽  
Fresnel Lenses ◽  
Linear Fresnel Lenses

Redistribution of LED radiation in lighting is necessary in many applications. In this article, we propose a new optical component design for LED lighting to achieve a higher performance. The design consists of a commercial collimator and two linear Fresnel lenses. The LED radiation is collimated by a collimator and redistributed by double linear Fresnel lenses to create a square-shaped, uniform distribution. The linear Fresnel lenses design is based on Snell’s law and the “edge-ray principle”. The optical devices are made from poly methyl methacrylate (PMMA) using a high-speed computer numerical control (CNC) machine. The LED prototypes with complementary optics were measured, and the optical intensity distribution was evaluated. The numerical results showed we obtained a free-form lens that produced an illumination uniformity of 78% with an efficiency of 77%. We used the developed LED light sources for field experiments in agricultural lighting. The figures of these tests showed positive effects with control flowering criteria and advantages of harvested products in comparison with the conventional LED sources. This allows our approach in this paper to be considered as an alternative candidate for highly efficient and energy-saving LED lighting applications.

FPGA-Based Intelligent Software Hardening Chip for Computer Numerical Control System

2011 ◽  
Vol 105-107 ◽  
pp. 2217-2220
Author(s):  
Mu Lan Wang ◽  
Jian Min Zuo ◽  
Kun Liu ◽  
Xing Hua Zhu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Large Scale ◽  
Position Control ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Cnc System ◽  
Intelligent Software

In order to meet the development demands for high-speed and high-precision of Computer Numerical Control (CNC) machine tools, the equipped CNC systems begin to employ the technical route of software hardening. Making full use of the advanced performance of Large Scale Integrated Circuits (LSIC), this paper puts forward using Field Programmable Gates Array (FPGA) for the functional modules of CNC system, which is called Intelligent Software Hardening Chip (ISHC). The CNC system architecture with high performance is constructed based on the open system thought and ISHCs. The corresponding programs can be designed with Very high speed integrate circuit Hardware Description Language (VHDL) and downloaded into the FPGA. These hardening modules, including the arithmetic module, contour interpolation module, position control module and so on, demonstrate that the proposed schemes are reasonable and feasibility.

Development of a Smart Computer Numerical Control System

2013 ◽  
Author(s):  
Zhiqian Sang ◽  
Xun Xu
Keyword(s):  
Real Time ◽  
High Speed ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Machining Process ◽  
Cnc Machine ◽  
Field Bus ◽  
Nc System ◽  
Tool Paths ◽  
Cnc Controller

Traditional Computer Numerical Control (CNC) machines use ISO6983 (G/M code) for part programming. G/M code has a number of drawbacks and one of them is lack of interoperability. The Standard for the Exchange of Product for NC (STEP-NC) as a potential replacement for G/M code aims to provide a unified and interoperable data model for CNC. In a modern CNC machine tool, more and more motors, actuators and sensors are implemented and connected to the NC system, which leads to large quantity of data being transmitted. The real-time Ethernet field-bus is faster and more deterministic and can fulfill the requirement of data transmission in the high-speed and high-precision machining scenarios. It can provide more determinism on communication, openness, interoperability and reliability than a traditional field-bus. With a traditional CNC system using G/M code, when the machining is interrupted by incidents, restarting the machining process is time-consuming and highly experience-dependent. The proposed CNC controller can generate just-in-time tool paths for feature-based machining from a STEP-NC file. When machining stoppage occurs, the system can recover from stoppage incidents with minimum human intervention. This is done by generating new tool paths for the remaining machining process with or without the availability of the original cutting tool. The system uses a real-time Ethernet field-bus as the connection between the controller and the motors.

scholarly journals A Feedrate-Constraint Method for Continuous Small Line Segments in CNC Machining Based on Nominal Acceleration

2021 ◽  
Vol 11 (19) ◽  
pp. 8837
Author(s):  
Peng Guo ◽  
Ronghua Wang ◽  
Zhebin Shen ◽  
Haorong Zhang ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Cnc Machining ◽  
Machining Process ◽  
Free Form ◽  
Cnc Machine ◽  
Line Segments ◽  
Machining Quality ◽  
Adjacent Line ◽  
Constraint Method

When the CNC machining of continuous small line segments is performed, the direction of the machine tool movement will change abruptly at the corner of adjacent line segments. Therefore, a reasonable constraint on the feedrate at the corner is the prerequisite for achieving high-speed and high-precision machining. To achieve this goal, a feedrate-constraint method based on the nominal acceleration was proposed. The proposed method obtains the predicted value of acceleration during the machining process by the machining trajectory prediction and acceleration filtering. Then, the feedrate at the corner is constrained, according to the predicted acceleration. Specifically, for any corner of adjacent line segments, the proposed method assumes that the CNC machining of a short path centered on the corner is carried out at a constant feedrate. First, the actual machining trajectory is predicted according to the transfer function of the servo system. Then, the nominal acceleration, when the CNC machining is carried out to the corner, is calculated and processed by a low-pass FIR filter. Last, the feedrate-constraint value at the corner is obtained according to the nominal acceleration and the preset normal acceleration. The advantage of the proposed method is that it can be used for different machining paths consisting of long segments or continuous small segments and it has no special requirement for the accuracy of the machining path. As a result, the feedrate-constraint value obtained is reasonable and the smooth machining process can be ensured. The simulation results in both 2D and 3D machining paths show that the proposed method is insensitive to the length of the line segment and the angle of the corner, and the calculated feedrate-constraint value is close to the theoretical value, which has good stability and versatility. In contrast, the feedrate-constraint values obtained by conventional methods change abruptly along the machining path, especially in the 3D simulation, which will damage the machining quality. The experiment was performed on a three-axis CNC machine tool controlled by a self-developed controller, and a free-form surface workpiece was machined by a conventional feedrate-constraint method and the proposed method, respectively. The experimental results showed that the proposed method can make the feedrate of the machining process higher and more stable. Then, machining defects such as overcutting and undercutting can be avoided and the machining quality can be improved. Therefore, the article proposes a new method to constrain the feedrate at the corner of continuous small line segments, which can improve the machining efficiency and quality of the CNC machining.

Recent Patents on the Structure of High-Speed Motorized Spindle

2019 ◽  
Vol 12 (2) ◽  
pp. 125-137
Author(s):  
Ye Dai ◽  
Wen-Qiang Wei ◽  
Xue-Liang Zhang ◽  
Yun-Shan Qi
Keyword(s):  
Research And Development ◽  
Machine Tool ◽  
High Precision ◽  
High Speed ◽  
Numerical Control ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Motorized Spindle ◽  
The Core ◽  
Spindle Structure

Background: As one of the core components of high-speed CNC machine tool, high-speed motorized spindle is the core functional component of high precision CNC machine tool, which has become the key research and development object of the world. Objective: By comparing and discussing the patents of high-speed motorized spindle, some valuable conclusions have been drawn to predict the future research and development of high-speed motorized spindle. Methods: By analyzing the characteristics of high-speed motorized spindle structure, the influence of high-speed motorized spindle on high-speed machining technology was explicated. Combining with the key technology of high-speed motorized spindle, the patents related to high-speed motorized spindle structure were used for investigation. Results: With the rapid development of high-speed cutting and numerical control technology and the need of practical application, the requirement for high-speed spindle performance has increased. Motorized spindle technology has the characteristics of high speed, high strength, high power, high torque and low speed, high precision, high reliability and long life, offering diversified bearing and lubrication cooling methods and serving as an intelligent system. Conclusion: The different levels of improvement and renovation of the structure with high-speed motorized spindle, by adding lubrication and cooling device to the spindle have improve the performance of spindle, addressing the loopholes in the technology and making it more practical.

Development of a High-Speed and High-Accuracy Machining System Based on Servo-Data Control – Evaluation of Prototype System –

2011 ◽  
Vol 5 (6) ◽  
pp. 855-861 ◽  
Author(s):  
Mikio Fujio ◽  
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Geometric Model ◽  
High Accuracy ◽  
Numerical Control ◽  
Prototype System ◽  
Cnc Machine Tool ◽  
Accuracy Control ◽  
Cnc Machine ◽  
Machining System

High-speed and high-accuracy control technology has been developed in Japan and applied to CNC (Computer Numerical Control) machine tools. Therefore, a CNC machine tool, which is made in Japan, has shown a successful history of its performance. Further development of these technologies is important for Japan to maintain its leadership in advanced manufacturing. The purpose of this research is to develop a high-speed and high-accuracy machining system. Two methods are implemented in the proposed prototype system. The first method is “geometric-model interpolation,” which is used to generate high-speed and highaccuracy command positions, and the second method is “predictive compensation,” which is used to correct machining errors. In the proposed prototype system, these errors are simulated preliminarily and compensated for in the servo data by controlling the position and the feed rate. This report describes the configuration of the proposed prototype system, and the performance of the prototype is evaluated by comparing its speed and accuracy with an existing commercial CNC machine tool. The results show that the prototype system is able to control a CNC machine tool with higher speed and greater accuracy than current CNC machine tool systems.

Computer Numerical Control Machine Tool and its Development Trend

2013 ◽  
Vol 774-776 ◽  
pp. 1458-1461
Author(s):  
Huan Yun Wang ◽  
Xiu Fen Liu
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Manufacturing Industry ◽  
High Reliability ◽  
Development Trend ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Control Machine Tool ◽  
Comprehensive Level

CNC machine tools are the key equipment in the equipment manufacturing industry, which is related to the national economic construction and strategic position, and is an important symbol reflecting the national comprehensive level. This article analyzes the emergency and characteristics of CNC machine tools and its development trend such as high precision, high speed, high reliability, complex, intelligent, flexibility, integration and openness.

The Closed-Loop Identification of Dynamic Parameters Based on Rigid Model for the Feeding System of Commercial Numerical Control Machine

2013 ◽  
Vol 694-697 ◽  
pp. 1855-1859
Author(s):  
Guang Sheng Chen ◽  
Hao Lin Li
Keyword(s):  
High Speed ◽  
Closed Loop ◽  
Servo System ◽  
Rotation Velocity ◽  
Numerical Control ◽  
Feeding System ◽  
Cnc Machine ◽  
Closed Loop Identification ◽  
Nc Machine ◽  
Control Machine

The precision of high-speed CNC (Computer Numerical Control) machine are greatly influenced by the dynamic characteristics of servo system. In this study, by investigating the motor of the servo system of CNC machine, an inertia and damping linear identification model is established using current as input signal and motor rotation velocity as output signal. Moreover, the excitation signal generation method based on G-code, concerning the closed-loop identification of servo system, is proposed. Furthermore, to verify the effectiveness of the closed-loop identification, an experiment is carried out on the feeding system of a commercial NC machine. The experiment results show that the proposed method performs well with effective stimulation, rapid convergence and accurate results.

Determination of Geometry-Based Errors for Interpolated Tool Paths in Five-Axis Surface Machining

2005 ◽  
Vol 127 (1) ◽  
pp. 60-67 ◽  
Author(s):  
O. Remus Tutunea-Fatan ◽  
Hsi-Yung Feng
Keyword(s):  
Tool Path ◽  
Kinematic Chain ◽  
Cnc Machining ◽  
Numerical Control ◽  
Free Form ◽  
Cnc Machine ◽  
Surface Geometry ◽  
Contact Points ◽  
Five Axis ◽  
Deviation Method

Five-axis computer numerical control (CNC) machining is characterized with a multitude of errors. Among them an important component comes from the computer-aided manufacturing software known as the geometry-based errors. A new and accurate method to determine these errors is presented in this paper as opposed to the conventional chordal deviation method. The present method allows establishing the exact linearly interpolated tool positions between two cutter contact points on a given tool path, based on the inverse kinematics analysis of the machine tool. A generic procedure has been developed to ensure wide applicability of the proposed method. Analytical derivation of the geometry-based errors provides insights regarding the origin of these errors and their affecting parameters. Due to the highly non-linear characteristics of the problem, analytical solutions can only be obtained for simple surface geometry. Numerical computation is able to determine the errors for general surface shapes but it would be difficult to uncover further insightful information from the calculated error values. Besides the local surface geometry, the configuration of the kinematic chain of the CNC machine has been found to be the primary factor controlling the resulting value and type of the geometry-based errors. Implementations with a typical complex free-form surface demonstrated that the conventional chordal deviation method was not reliable and could significantly underestimate the geometry-based errors.

scholarly journals Generation Method of Cutting Tool Paths for High-Speed and High-Quality Machining of Free-Form Surfaces

2021 ◽  
Vol 15 (4) ◽  
pp. 521-528
Author(s):  
Yuki Takanashi ◽  
Hideki Aoyama ◽  
Song Cheol Won ◽  
◽  
Keyword(s):  
High Speed ◽  
Processing Time ◽  
Free Form ◽  
Machining Accuracy ◽  
Cnc Machine ◽  
Block Processing ◽  
Tool Paths ◽  
Nc Program ◽  
Straight Line ◽  
Free Form Surfaces

In general, NC programs for machining free-form surfaces using a computer numerical control (CNC) machine tool are generated using a computer-aided manufacturing (CAM) system. The tool paths (CL data) generated by a CAM system are approximated straight-line segments based on tolerance (allowable error). As a result, the tolerance affects the machining accuracy and time. If the tolerance is set to a small value, the lengths of the segments are shortened, and the machining accuracy is improved. The process in which a CNC machine tool reads and analyzes an NC program and controls the motors requires a minimum processing time of an NC program block (block-processing time). Therefore, if the lengths of the approximated straight-line segments are too small, it will be impossible to reach the indicated feed speed, and the machining time will be longer. In this study, by identifying the block-processing time of a CNC controller and deriving the appropriate length of the approximated straight-line segment based on the block-processing time, a CL data creation method that is capable of high-speed and high-accuracy free-form surface machining is proposed. In addition, experimental verification tests of the method are conducted.

Friction compensation using a double pulse method for a high-speed high-precision table

2011 ◽  
Vol 225 (5) ◽  
pp. 1263-1272 ◽  
Author(s):  
G S Chen ◽  
X S Mei ◽  
T Tao
Keyword(s):  
High Precision ◽  
High Speed ◽  
Dead Zone ◽  
Pulse Method ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Response Analysis ◽  
Cnc Machine ◽  
Time Duration ◽  
Loop Control

Friction error in reverse motion is one of the principal factors influencing the contour accuracy of high-speed and high-precision computer numerical control (CNC) machine tools, on which closed-loop control is used. On the basis of transient response analysis of servo systems which a conventional proportion–integration–differentiation control strategy are used, the reason for quadrant protrusions occurring in circular motion for worktables is discovered, and the characteristics of the friction error during the feed process such as emergence time, duration, and magnitude of the error due to friction can be predicted correctly. A new approach of compensating for friction error using double compensation pulses is proposed in this article. The first compensation pulse made the worktable escape from the dead zone at the best times, and the second one made the worktable approach to the ideal feed path along the guide as fast as possible. Parameters of compensation pulses such as magnitudes, widths, and starting time are determined by simple mathematic calculation. Results of simulations and experiments show that the method using double pulses proposed in this article can effectively compensate for the friction error in circular motions for a high-speed and high-precision table.

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