Considering Machining Tolerances in High Speed Corner Tracking

Author(s):  
Sepehr Zarifmansour ◽  
Rudolf Seethaler

Growing industrial demand for faster machine tools, makes feed-rate and trajectory optimization a challenging problem in machining processes. One of the most challenging machining operations for computer numerically controlled (CNC) machine tools is corner tracking. In this scenario, most of the conventional feed-rate optimization approaches sacrifice speed for accuracy. This paper, proposes a new feed-rate and trajectory optimization algorithm for CNC machines. At each corner of the trajectory, the presented algorithm regenerates the trajectory, using a circular move within a desired tolerance limit. Then, a new feed rate optimization method is employed, which enables the machine tool to travel at the maximum feasible velocity through the corners, while taking acceleration constraints into account. Experimental results for different desired tolerances indicate that the new algorithm achieves significantly shorter travel times than the theoretical minimum time trajectory with zero tolerance.

Manufacturing ◽  
2003 ◽  
Author(s):  
Donald Esterling ◽  
F. Donald Caulfield ◽  
Aaron Kiefer ◽  
Gregory Buckner ◽  
Pavan Jaju

The frequency response function (FRF) of a CNC machine tool is composed of tool/toolholder/spindle dynamics, and plays an important role in determining the stability of high speed machining processes. This paper details the design, development and operational verification of a non-contacting, controllable, electromechanical actuator (EMA) for measuring the FRFs of tools mounted in CNC milling machines. Although standard modal testing methods are available and provide similarly accurate results, these test procedures are difficult to perform in machine shop environments and can require expensive equipment. The EMA developed as part of this research extends the capabilities of the NIST “best speeds device” to provide controllable, non-contacting excitation for modal tests on machine tools. This EMA device offers the advantages of being accurate, easy to use, and applicable to a wide variety of tools and operating conditions.


2020 ◽  
Vol 19 (01) ◽  
pp. 65-85
Author(s):  
Chuan-Hsun Hsu ◽  
Chi-Hsiang Wang ◽  
Syh-Shiuh Yeh

Backlash, friction, and servo lag factors often result in protrusion or segment difference phenomenon in the moving speed reversal of a machine tool’s moving table. This phenomenon can be improved by adjusting the backlash control parameters of the machine tool controller, but the control parameters must vary with the feed rate and payload of the moving table. Therefore, this study performed the circular test process for CNC machine tools, and used different feed rate, radius, and payload motion conditions to discuss the effect of backlash control parameters on quadrant protrusions. First, this study used parameter-range reduction combined with the Taguchi method and the binary search algorithm to search for the optimal backlash control parameters in the parameter setting range, so that the machine tool could have preferable quadrant protrusion performance when executing circular tests. Afterward, the correlation of the moving table feed rate, radius, and payload to the quadrant protrusion was analyzed according to the experimental results. The results indicated that the machine tool moving table feed rate had the most apparent effect on quadrant protrusions, and the relationship between the payload and quadrant protrusion was influenced by the moving table feed rate and circular radius simultaneously.


2007 ◽  
Vol 10-12 ◽  
pp. 621-625
Author(s):  
X.S. Wang ◽  
Jian Guo Yang

This article sets forth a new precision measurement method of CNC machine tools. The method incorporates the laser interferometer and the measurement principle of the double ball bar (DBB), and can measure the machine tool precision under the high feed rate condition. The generalized measurement model of three-axis has been built. Data analysis software is developed to simulate the run condition of machine tools. The repeatable experiment results proves that the method is feasible and its precision is higher than DBB`s.


2018 ◽  
Vol 224 ◽  
pp. 01020 ◽  
Author(s):  
Georgi M. Martinov ◽  
Akram Al Khoury ◽  
Ahed Issa

Nowadays, there is a big demand on using small sized CNC machine tools, which have low price tag, wide range of implementations, low manufacturing costs and can be used for educational purposes. These machines can achieve casual manufacturing routines, like milling and drilling in applications, where there is no need for high speed performances and super quality of products. In this work, we proposed a model of CNC for these machines and analysed its components and efficiency. The model consists of three main layers: CNC system (application layer), ARM based microcomputer as CAN master and controller (connecting layer) and Servo-Drive Step Motors (actuating layer).


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