Papers by Keyword: Machining Error

Abstract: For a cutting process using a low-rigidity end mill, it is very important to be able to estimate the machining error caused by the deflection of the tool. The purpose of this study is to establish a method for the real-time estimation of the machining error caused by the deflection of the tool at the cutting point of a ball-end mill. The method was verified by comparing the estimated deflection and the machining error when milling an inclined surface. It was concluded that the machining errors in ball-end milling of inclined surfaces can be estimated from the normal force at the moment when the radial direction of the peripheral cutting edge is normal to the feed direction of the tool.

Abstract: Industrial parts with sculptured surfaces are typically, manufactured with the use of CNC machining technology and CAM software to generate surface tool paths. To assess tool paths computed for 3-and 5-axis machining, the machining error is evaluated in advance referring to the parameter controlling the linearization of high-order curves, as well as the scallop yielded as a function of radial cutting engagement parameter. The two parameters responsible for the machining error are modeled and corresponding cutter location data for tool paths are utilized to compare actual trajectories with theoretical curves on a sculptured surface assessing thus the deviation when virtual tools are employed to maintain low cost; whilst ensuring high precision cutting. This operation is supported by applying a flexible automation code capable of computing the tool path; extracting its CL data; importing them to the CAD part and finally projecting them onto the part’s surface. For a given tolerance, heights from projected instances are computed for tool paths created by changing the parameters under a cutting strategy, towards the identification of the optimum tool path. To represent a global solution rough machining is also discussed prior to finish machining where the new proposals are mainly applied.

Abstract: For a cutting process using a low-rigidity end mill, it is very important to be able to estimate the degree of machining error caused by the deflection of the tool. The purpose of this study is to establish a method of estimating, in real time, the machining error caused by the deflection at the cutting point of an end mill. To this end, in this research, a method for estimating the machining error caused by the deflection of the tool used for the ball-end milling of a hemispherical surface was verified by comparing the estimated and measured deflections of the tool. As a result, it was found that the machining errors in ball-end milling could be estimated from the normal force at the moment when the radial direction of the peripheral cutting edge is normal to the feed direction of the tool.

Abstract: The existing processes of controlling machining error just controlled the maximum error. However, it did not effectively control the distribution of the error.The reliability of the assembly precision of the key joint surface did not meet the requirements, thereby affecting the service performance of machine tool. To solve this problem, the error matrix and transformation matrix was used to ascertain the location of joint surface positioning error occurred. The influence of processing error on the the positioning accuracy of machine tool was analyzed. The control objective of milling process was proposed. At the same time, the effects of cutting parameters on the processing error were also studied according to the milling experiments. The process error and its distribution characteristics of joint surface were obtained by analyzing the relationship between deformation of joint surface and cutting parameters. The milling process control methods were proposed.

Abstract: Research on spatial error modeling of the glass fillet machine is introduced based on the basic principles of multi-body system kinematics. Firstly, the topological structure and the low-order body arrays are described on the basis of the mechanical structure. Then, the spatial error analysis is carried out based on the theory of multi-body system. At the same time, the transformation matrix between the adjacent typical bodies is written. After that, in order to illustrate the relationship between the grinding wheel and the grinding point, the space error model of the glass fillet machine is established, which explains the effect of spatial structure on machining error and the calculation method of machining error. This model is easy to analyze the error and embodies the superiority on the error analysis and correction. Thus it provides a kind of ideal technique for the precision analysis of the glass fillet machine.

Abstract: Fast tool servo (FTS) is widely utilized to fabricate optical freeform surfaces with nanometric surface roughness and with sub-micrometric form errors. FTSs dynamics character plays the major part in many factors that influence machining error. In this paper, a dynamic model for FTS is built up to describe its dynamic and to analyze the effects on machining error under different work frequencies. It was found that FTS dynamic mainly affect the Y direction machining accuracy of the workpiece surface, with the increase of the working frequency of FTS, the error caused by FTS dynamic also increases rapidly.

Abstract: A micro dimple machining is studied to control the surface functions with the micro-scale structures on the solid surfaces. The micro dimples are machined in milling with the inclined ball end mill. When the feed rate of the tool is high enough that the removal area of an edge does not overlap with that of the previous edge, periodical concave dimples are machined. A mechanistic model is presented to control the shape and the size of the dimples to be machined. Then, a machining error model is presented to control the deviation of the dimple shapes. Some machining examples are shown to verify the dimple model and the error model.

Abstract: Generally speaking, the error in machining is an important indicator measuring the accuracy of finished surface. The machining error often occurs in numerical control milling. Such error will be influenced by multiple factors, such as cutter wear, thermal deformation, machine tool deformation, vibration or positioning error. Nowadays, though our science and technology develops rapidly, machining error problem in numerical control milling occurs frequently. At present, several methods can be applied to forecast machining error problems in numerical control milling, including on the basis of machining theory, experimental study, design study and artificial intelligence. The analysis and forecast of machining error problems in numerical control milling can to some extent improve the degree of machining errors so as to promote the machining accuracy in milling. The author expresses the views on machining error problems according to current situations of numerical control milling.

Abstract: This paper analyzes the factors affecting the machining accuracy. Specific analysis of the causes of error, and take appropriate precautions to reduce processing errors, improve the machining accuracy.

Abstract: Much progress has been made in the machine tool technologies, aimed at improving the performances of the machine tools from various viewpoints, such as accuracy, reliability, produc-tivity, and flexibility. The machining accuracy is one of the most important characteristics of the machine tools. From the viewpoints of the design and the manufacturing of the machine tools and their components, one of the important issues is to clarify the relationships between the kinematic motion deviations of the machine tools and the geometric tolerances of the components, such as the guide ways and the bearings. The objective of the present research is to establish mathematical models representing the kinematic motion deviations of the machine tools, on the basis of the geo-metric tolerances of the components, and to apply the models to analysis of the kinematic motion deviations.