Papers by Keyword: Machining Precision

Abstract: the numerical control milling process design is on the basis of ordinary milling process design, combining with the characteristics of CNC milling machine, give full play to its advantages. CNC milling process design is the key to reasonable arrangement of process route, to coordinate the relationship between the CNC milling process and other process, determine the content and steps of NC milling process make the necessary preparations for programming. NC milling machining process analysis is related to the effectiveness and success or failure, is one of the important preparations before programming. This article will mainly for NC milling machining precision and machining error analysis and research.

Abstract: In this study, we firstly developed a numerical electrochemical micro-machining (EMM) setup. Furthermore, the effects of five vital process parameters, applied voltage, electrolyte type, electrode shape and diameter, electrode feed rate on micro-seams machining accuracy and process stability were evaluated. The experimental results show that: Wire electrodes machining accuracy is higher than that of sheet electrode. With the wire electrodes diameter decreased from 0.2mm to 0.06mm, micro-seam width is reduced by 36.55%. With the wire electrode feed rate increased from 0.2mm/min to 0.6mmm/min, micro-seam width is reduced by 44.2%. Sheet electrodes machining stability is better than that of wire electrode. The number of machining stability of sheet electrode is 25% higher than that of wire electrode in the condition of 8V applied voltage.

Abstract: Based on the saddle-point approximation theory, the reliability sensitivity formula is derived systematically. Then, combining the reliability theory with the sensitivity analysis method, the reliability-based sensitivity of machining precision for ball-end milling cutter is analyzed. Based on the premise that the probability distribution of random parameters is known, firstly, the saddle-point approximation theory is employed to solve the reliability of machining precision for ball-end milling cutter and, as a result, the saddle-point approximation method is proved accurate with higher speed in comparison with the Monte-Carlo method. Secondly, the reliability-based sensitivity is calculated. Finally, the effect of changes in machining parameters on the reliability of machining precision is analyzed.

Abstract: The error due to tool deflection is detrimental to machining precision. In order to predict tool deflection more accurately, this paper presents a special three segments cantilever beam model for ball-end tool deflection in sculptured surface milling. Different from the traditional two segments cantilever beam method, the ball-end tool is divided into the shank, the flute and the ball-end parts in this new model. Then the ball-end tool deflection is simulated also by utilizing the finite element software ANSYS 12.0 Workbench to calibrate the accuracy of the tool deflection models. The three segments cantilever beam model for ball-end tool deflection matches better the finite element method (FEM). In the last part of the paper, the sculptured surface machining experimental results show that, the surface precision after tool deflection compensation based on the new three segments cantilever beam model is higer than that based on the two segments cantilever beam model.

Abstract: The imprinter bottom roller is under very high linear pressure during the work, which often causes wear and damage between bottom roller and anvil roller. Traditionally, the extra strength design method is frequently used in the design of imprinter bottom roller, which leads to the waste of materials and increase of weights. So, reasonable processing craft and appropriate theoretical analysis method should be adopted to improve the manufacturing of bottom roller and make the material strength into full use, in the condition of meeting the structure safety standard. This paper gives a brief analysis of the process craft of bottom roller and uses finite element technique to give the bottom roller numerical simulation and FEA of its deflection and strength. The results show that: in the process of work, the distribution of stress changes largely and unevenly. The stress and deformation in middle part prove the largest with decreasing to both sides successively. The imprinter bottom roller produces a maximum displacement of 0.0516 mm, which meets the work requirements.

Abstract: With the wide use of NC, higher accuracy in machining is increasingly required for premium mechanical components. However, machining accuracy is affected by many factors, especially by the way of the tool positioning and the geometry of the tool nose. This paper, based on the actual NC lathe tool and turning, generalized and abstracted the machining process by establishing the imaginary tool nose and the tool tip’s arc centre as the cutter-contact point, and analyzed systematically the influence of the factors, including the way of the tool positioning, the nose, and the tool tip’s arc radius, on the machining accuracy when machining transverse, cylindrical-surface, circular cone, quarter-circular and some surfaces can be expressed by formula etc.. Derived the error calculating formulas for turning in different surfaces. Put forward two error compensation methods, direct calculating method and enveloping method of error compensation. Experiments were carried out and results have shown that the two error compensation methods can considerably reduce the machining error in NC turning operations.

Abstract: Many factors influence WEDM(Wire-cut Electrical Discharge Machining) machining precision, and the influence of various factors on the machining precision are expressed by wire electrode dynamic form ultimately. In this paper, the transverse vibration theoretical model of the axially moving electrode wire coupled with thermal stresses is established by the principle of Hamilton. The influence of various processing parameters on machining precision are analyzed and simulated. This study provides a relevant theoretical basis for optimizing processing parameters, reducing the wire vibration and improving machining precision of workpiece.

Abstract: The research way is discussed in this paper is to use digital image processing technology to measure the coordinates (x0, y0)，the radius distribution for industrial product with cylinder Holes， as well as the machining dimension error which forms as a result of all sorts of disturbances in machining course, as the small eccentricity、the ellipticity、three side prism 、four side prism and so on , by this we can also find a just way to improve the numerical control machining precision.

Abstract: Fabrication pioneer production with lower cost and shorter cycle is a major mission for an enterprise, and rapid prototyping is a digital manufacture technology based on discrete stacking, which can meet the requirement. Rapid prototyping technology can be used to machine complex physical part directly from CAD data without any cutter or technical equipments. The paper summaries the working principle and compares the application fields, machining cost and process parameters for four typical rapid prototyping technology. Finally, the significant performance of rapid prototyping for modern industry is discussed, and the merits and faults is analysed. The investigation is beneficial for choosing an optimal forming process in industry.

Abstract: The performance of anti-disturbance is a key problem in the process of middle-convex and varying ellipse piston machining. In practical application, the system can easily trace external periodical signal off-load. But if anti-disturbance can not reach requirement, the capability of tracing reference signal will reduce severely to influence machining precision on-load. The disturbance restraint for varying load to linear servo drive system is studied in the paper and the disturbance of cutting force varying periodically is pointed out. A new control strategy integrates repetitive control with iterative learning control algorithm is proposed in order to reduce the influence of load disturbance to tool position. A new train of thought to improve middle-convex and varying ellipse piston machining precision is proposed in the paper.