A new error compensation model for machining process based on differential motion vectors

2017 ◽  
Vol 93 (5-8) ◽  
pp. 2943-2954 ◽  
Author(s):  
Fuyong Yang ◽  
Sun Jin ◽  
Zhimin Li ◽  
Siyi Ding ◽  
Xun Ma
Keyword(s):  
Error Compensation ◽  
Machining Process ◽  
Motion Vectors ◽  
Compensation Model ◽  
Differential Motion ◽  
Differential Motion Vectors

A modification of DMVs based state space model of variation propagation for multistage machining processes

2017 ◽  
Vol 37 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Fuyong Yang ◽  
Sun Jin ◽  
Zhimin Li
Keyword(s):  
Current Model ◽  
Propagation Model ◽  
Machining Processes ◽  
Motion Vectors ◽  
Content Type ◽  
Model Based ◽  
Differential Motion ◽  
Variation Propagation ◽  
Current Variation ◽  
Differential Motion Vectors

Purpose Complicated workpiece, such as an engine block, has special rough locating datum features (i.e. six independent datum features) due to its complex structure. This locating datum error cannot be handled by current variation propagation model based on differential motion vectors. To extend variation prediction fields, this paper aims to solve the unaddressed variation sources to modify current model for multistage machining processes. Design/methodology/approach To overcome the limitation of current variation propagation model based on differential motion vectors caused by the unaddressed variation sources, this paper will extend the current model by handling the unaddressed datum-induced variation and its corresponding fixture variation. Findings The measurement results of the rear face with respect to the rough datum W and the pan face with respect to the hole Q by coordinate measuring machine (CMM) are −0.006 mm and 0.031 mm. The variation results for rear face and pan face predicted by the modified model are −0.009 mm and 0.025 mm, respectively. The discrepancy of model prediction and measurement is very small. Originality/value This paper modifies the variation propagation model based on differential motion vectors by solving the unaddressed variation sources, which can extend the variation prediction fields for some complicated workpiece and is useful in the future work for many fields, such as process monitoring, fault diagnosis, quality-assured setup planning and process-oriented tolerancing.

On-line first-order machining error compensation for thin-walled parts considering time-varying cutting condition

2021 ◽  
pp. 1-16
Author(s):  
Xiong Zhao ◽  
Lianyu Zheng ◽  
Yuehong Zhang
Keyword(s):  
Error Compensation ◽  
Compensation Method ◽  
Cutting Condition ◽  
Time Varying ◽  
Machining Error ◽  
Process Step ◽  
Compensation Model ◽  
First Order ◽  
On Line ◽  
Thin Walled

Abstract Mirror error compensation is usually employed to improve the machining precision of thin-walled parts. However, this zero-order method may result in inadequate error compensation, due to the time-varying cutting condition of thin-walled parts. To cope with this problem, an on-line first-order error compensation method is proposed for thin-walled parts. With this context, firstly, the time-varying cutting condition of thin-walled parts is defined with its in-process geometric and physical characteristics. Based on it, a first-order machining error compensation model is constructed. Then, during the process planning, the theory geometric and physical characteristic of thin-walled parts are respectively obtained with CAM software and structure dynamic modification method. After process performing, the real geometric characteristic of thin-walled parts is measured, and it is used to calculate the dimension error of thin-walled parts. Next, the error compensated value is evaluated based on the compensation model, from which, an error compensation plane is constructed to modify the tool center points for next process step. Finally, the machining error is compensated by performing the next process step. A milling test of thin-walled part is employed to verify the proposed method, and the experiment results shown that the proposed method can significantly improve the error compensation effect for low-stiffness structure, and thickness precision of thin-walled parts is improved by 71.4 % compared with the mirror error compensation method after machining.

Positioning Error Compensation for Machining Center Based on Spline Interpolation

2012 ◽  
Vol 472-475 ◽  
pp. 3029-3034
Author(s):  
Peng Li ◽  
Ying Hu ◽  
Zi Ma
Keyword(s):  
Error Compensation ◽  
Laser Interferometer ◽  
Spline Interpolation ◽  
Machining Process ◽  
Accuracy Evaluation ◽  
Positioning Error ◽  
Positioning Errors ◽  
Machining Center ◽  
Compensation Function ◽  
Manual Correction

Related to the machining precision, especially for the middle and low end machining center, the positioning error is often considered as a major factor, which can be traditionally decreased by the pitch compensation function integrated in the CNC system. However, the function is just founded on that all of positioning errors remain constant in the machining process, and it is difficulty to meet the compensation needs in different machining condition. At the same time, it involves a mass of parameters that need professional manual correction. Therefore, the software error compensation method is put forward. Firstly, based on cubic spline interpolation, the error compensation model is designed through the processing of positioning error which is collected by the laser interferometer. Secondly, with the characteristics of G codes, the database is established for error compensation, which can effectively correct different machining G codes with enough error information. Finally, by the experiment and accuracy evaluation, results show that after the positioning error of machining center is compensated by the presented scheme, its precision is improved obviously.

Generalized definition and application of tolerance

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6807-6814
Author(s):  
Hao Jianjun ◽  
Wang Youli ◽  
Wang Xiaohui
Keyword(s):  
Error Compensation ◽  
Extreme Values ◽  
Probabilistic Method ◽  
Tolerance Analysis ◽  
Machining Process ◽  
Negative Number ◽  
Absolute Value ◽  
Calculation Results ◽  
Relationship Of ◽  
Dimensional Homogeneity

Tolerance with upper deviation less than lower deviation is defined as virtual tolerance; the dimension between two extreme values required with tolerance (virtual tolerance) is expressed by a set. The changed characteristics of the set range when the tolerance value is continuously reduced from positive to negative are explored. The nature of virtual tolerance is that the absolute value of virtual tolerance is the error compensation amount, and the dimension between two extreme values is the error compensation range. On the basis of the concept of positive and negative number, the theory of dimensional homogeneity, the existing conditions of the general formula of the dimensional chain, the accuracy of the calculation results of tolerance, and so on, the concept of virtual tolerance and its relationship of unity of opposites with tolerance are proposed. Based on the concept of virtual tolerance, analysis and calculation processes of various assembly dimensional chains are unified, and general formulation of calculating the range of false waste is established, and the method of determining the range of false waste by using probabilistic method in machining process is deduced.

Analysis on the Thermal Error Compensation Model of Direct-Drive A/C Bi-Rotary Milling Head

2011 ◽  
Vol 87 ◽  
pp. 59-62
Author(s):  
Peng Zheng ◽  
Xin Bao ◽  
Fang Cui
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Thermal Deformation ◽  
Thermal Error ◽  
Direct Drive ◽  
Cnc Machine ◽  
Compensation Model ◽  
Axis Rotation ◽  
Thermal Error Compensation ◽  
Deformation Error

The thermal deformation error that is the biggest error of effecting the machining precision of Direct-drive A/C Bi-rotary Milling Head was narrated in brief. Based on the introduce of the study status on the thermal error compensation techniques of CNC Machine tool, the momentum of thermal deformation of Bi-rotary Milling Head was analyzed. According to the Trigonometric Relations in A/C axis rotation angle of Bi-rotary Milling Head and the momentum of thermal deformation in Bi-rotary Milling Head and -axis respectively, a thermal error compensation model was established to make the Machine tool to compensate for thermal errors in -axis.

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