Papers by Keyword: Subdivision

Abstract: In this paper, we have presented a method to generate efficient NC tool paths based on the surface subdivision. The main objective is to achieve high efficiency in the machining of sculptured surface. The NC machining efficiency can be improved by segmenting the whole surface into distinct areas according to the characters of sculptured surface and by using different size mills and different tool path planning methods to machine the areas. The iso-parametric method and large mills are used in the curvature changing little areas. While the iso-scallop method and small mills are used in curvatures changing large areas. This can make full use of tool path generation methods and mills, which improve the machining efficiency of sculpture effectively.

Abstract: High-speed machining puts forward higher requirements not only for tools and fixtures, but also for the tool path patterns with the development of manufacturing. The focus is on analyzing different characteristics of tool path patterns, and influencing factors of choice in milling curvature-mutated surface. Then a reasonable choice is presented on the principle of tool path patterns. According to surface features, milling characteristics and programming requirements, the surface with the curvature changing seriously is subdivided into two patches, thus the subdivision surfaces are roughing machining. Finally, Powermill is used to verify further its feasibility.

Abstract: This paper, based on the EDA software platform and VHDL description method, introduces how to use the FPGA chip to control the multiphase stepper motor. This design, through automatic logic compilation optimization and simulation test and compile, finally completed the function of the stepping motor subdivision drive controller. By testing, it can achieve controlling positive &negative and subdivision for stepper angle.

Abstract: Movement frequency of atmospheric turbulence is varied between a few Hz to hundreds Hz. when laser is transmitted in atmospheric some characteristic will be changed by turbulence modulation. The energy distribution form and shape of spot will be varied with movement frequency of turbulence. When spot is detected by four-quadrant detector output of detector will be effect. In order to test effect of turbulence to detector and ensure output signal can be amplified and processing effectively a kind of spot detection circuit was designed in turbulent environment. Two bands amplification was used in system. The noise suppression was completed in first band and variable gain amplifier was used in second to meet require of light intensity. Testing system was set up which can research characteristic of quadrant detector in turbulence. Experiment of spot detection in field was done. Distance from transmitting to receiving is 800m and 12.5km. Conclusions have been obtained by experimental when Distance is 800m subdivision can be up to 7 in photosensitive surface. At the same time we can see that impact of turbulence on laser transmission is a combination result with modulation of high and low frequency. And ability to spot detection has been invalid in 12.5 kilometers distances because of photosensitive surface occupied by noise from impact of turbulence, which show subdivision of quadrant detector has been broken in long distance.

Abstract: In order to improve the step accuracy of two-phase hybrid stepping motors, this paper presents a high-performance stepping motor driver based on controllable dead-time compensation. After CPLD(Complex Programmable Logic Device) logical processing, the subdivision drive signal created by microcontroller STM32 becomes a complementary dead-time compensation drive signal which can realize precise control of stepper motor. The experiment shows that this program not only has effectively reduced the power consumption of the stepping motor, but also made whole system cost less.

Abstract: For stepper motor motion control problem of tailoring machine,the paper designed control system based on the LPC2138 and SLA7062 stepper motor subdivision , and realize of high-precision stepping motor subdivision control. Experimental results show that the stepper motor can be subdivided under the control of the control system stable and accurate operation, tailoring machines can meet the accuracy requirements.

Abstract: For the purpose of improving the interference resistance and accuracy of the grating detection system, a SCM-based software design method for grating signal processing is proposed in the thesis. In the method, two differential signals output from the grating detection circuit are amplified and shaped via the conditioning circuit, converted into digital quantity through AD conversion and processed by the SCM. Relying on the programming, properties of direction discrimination and subdivision are attained while effective computation accuracy of subdivided data and signal processing speed are guaranteed. The software processing method simplifies system hardware circuit, cuts down the cost, improves the resolution and measurement precision of the system due to the stable performance and strong interference resistance. The method is experimentally proved to be practical and worthy of promotion, which can be utilized in machine tool reform and relevant position detection systems.

Abstract: In this paper we propose a new kind of geometry driven subdivision scheme for curve interpolation. We use cubic Lagrange interpolatory polynomial to construct a new point, selecting parameters by accumulated chord length method. The new scheme is shape preserving. It can overcome the shortcoming of the initial four point subdivision scheme proposed.

Abstract: In order to enhance the processing efficency of complex cavity surfaces by using iso-scallop height method, a subdivision method based on the improved image direction information measure is proposed in this paper. According to the relationship between maximum cutting bandwidth and cutting direction in the theory of iso-scallop height, the method constructed an optimal cutting direction angle field image in the u-v system of parameters firstly; and then an improved direction information measure definition which combined with the characters of the angle field image was proposed; Finally, the subdivision boundary for mold cavity surface was identified by using the direction measure as the edge characteristic index. Experimental results indicate that the proposed method demonstrates good performance in distinguishing and extracting boundary points of surface subdivision.

Abstract: The Brushless Direct Current Motor (BLDCM) has been researched by many scholars because of its simple structure, high power density, high reliability and easy control. In this paper, a driver based on the system on a programmable chip (SOPC) is designed to implement adjustable subdivision. For SPWM, SVPWM frequency conversion control Direct Digital Synthesizer(DDS) is introduced, DDS Intellectual Property (IP) core is designed for motor control of frequency conversion. This driving system can solve the high subdivision problem, increase the driving torque and angle resolution, and smooth the motor angle. Employing the bottom-top design method, the circuit was described by the VHDL language, synthesized by integrated environment, and simulated by Modelsim in both behavior level and gate level through the PLI interface. According to experiment’s result, this driver has the advantages of easy debugging, high anti-interference ability, larger driving power, low volume and low cost in large scale production.