Smooth Cornering Strategy for High Speed CNC Machine Tools With Confined Contour Error

2016 ◽  
Author(s):  
Shingo Tajima ◽  
Burak Sencer
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Cnc Machine Tools ◽  
Contour Error ◽  
Smoothing Algorithm ◽  
Cnc Machine ◽  
Computationally Efficient ◽  
Positioning Systems ◽  
Tool Paths ◽  
Time Optimal

Conventional tool-paths for CNC (computer numerical controlled) machine tools or NC positioning systems are mainly composed of linear motion segments, or so called the G1 commands. Interpolating along linear tool-paths exhibits serious limitations in terms of achieving the desired part geometry and productivity in high-speed machining. Velocity and acceleration discontinuities occur at the junction points of consecutive segments. In order to generate smooth and continuous feed motion, a kinematic corner smoothing algorithm is proposed in this paper, which plans smooth acceleration and jerk profiles around the segment junction to realize continuous velocity transition between consecutive linear segments. The proposed corner-smoothing algorithm eliminates the need for geometry based corner-blending techniques and presents a computationally efficient interpolation scheme. The cornering error is controlled analytically allowing the end-user to control the cornering tolerance. Drive’s acceleration and the jerk limits are fully utilized to minimize overall cornering duration. This delivers a time optimal cornering motion within user specified cornering error tolerances. Simulation studies are used to demonstrate the effectiveness of proposed high-speed cornering scheme.

Modeling and Control of Contouring Errors for Five-Axis Machine Tools—Part II: Precision Contour Controller Design

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Burak Sencer ◽  
Yusuf Altintas
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Sliding Mode ◽  
Kinematic Model ◽  
Cnc Machine Tools ◽  
Sculptured Surfaces ◽  
Cnc Machine ◽  
Control Approach ◽  
Tool Paths ◽  
Five Axis

The accurate tracking of tool-paths on five-axis CNC machine tools is essential in achieving high speed machining of dies, molds, and aerospace parts with sculptured surfaces. Because traditional CNCs control the tracking errors of individual drives of the machine, this may not lead to desired contouring accuracy along tool-paths, which require coordinated action of all the five drives. This paper proposes a new control approach where the tool tip and tool orientation errors, i.e., the contouring errors, are minimized along the five-axis tool-paths. The contouring error and kinematic model of the machine, which are presented in Part I of the paper, are used in defining the plant. A multi-input–multi-output sliding mode controller, which tries to minimize path tracking and path following velocity errors, is introduced. The stability of the system is ensured, and the proposed model is experimentally demonstrated on a five-axis machine tool. The path errors originating from the dynamics of five simultaneously active drives are significantly reduced.

An Analytical C3 Continuous Local Corner Smoothing Algorithm for Four-Axis Computer Numerical Control Machine Tools

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Qin Hu ◽  
Youping Chen ◽  
Jixiang Yang ◽  
Dailin Zhang
Keyword(s):  
Machine Tools ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Smoothing Algorithm ◽  
Linear Motion ◽  
Tool Orientation ◽  
Cnc Machine ◽  
B Splines ◽  
Rotary Axes ◽  
Tip Position

Linear motion commands of multi-axis computer numerical control (CNC) machine tools need to be smoothed at the transition corners, because the velocity discontinuities at corners can result in fluctuations on machine tool motions and lead to poor surface quality. However, no research has been reported on local corner smoothing algorithm for four-axis CNC machine tools with two rotary axes by considering their special kinematic characteristics. To this end, this paper proposes an analytical C3 continuous local corner smoothing algorithm for four-axis CNC machines with two rotary axes. After coordinates transformation, the tool tip positions and tool orientations are smoothed by locally inserting specially designed three-dimensional (3D) quintic B-splines and one-dimensional (1D) quintic B-splines into the corners between linear motion segments, respectively. The smoothing algorithm guarantees C3 continuity of the tool tip position and C3 continuous synchronization of the tool orientation related to the tool tip position, through analytically evaluating control points of the inserted microsplines. The maximum error tolerances of the tool tip position and tool orientation are mathematically constrained. Experiments on an in-house developed four-axis machine verify the efficacy of the proposed algorithm, where maximal errors caused by the local corner smoothing algorithm are constrained, the synchronization of the tool orientation and the tool tip position are achieved, and the proposed C3 continuous corner smoothing algorithm has lower jerk and jounce but higher tracking and contour accuracy than C2 continuous algorithm.

scholarly journals An approach of developing low cost ARM based CNC systems by controlling CAN drives

2018 ◽  
Vol 224 ◽  
pp. 01020 ◽  
Author(s):  
Georgi M. Martinov ◽  
Akram Al Khoury ◽  
Ahed Issa
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Low Cost ◽  
Cnc Machine Tools ◽  
Application Layer ◽  
Cnc Machine ◽  
Servo Drive ◽  
Wide Range ◽  
Quality Of Products

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).

Non-Contact Device for Measuring Frequency Response Functions of CNC Machine Tools

Manufacturing ◽  
2003 ◽  
Author(s):  
Donald Esterling ◽  
F. Donald Caulfield ◽  
Aaron Kiefer ◽  
Gregory Buckner ◽  
Pavan Jaju
Keyword(s):  
Frequency Response ◽  
Machine Tools ◽  
High Speed ◽  
Operating Conditions ◽  
Modal Testing ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Machining Processes ◽  
Test Procedures

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.

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