scholarly journals High Performance Rotary Table for Machine Tool Applications

2009 ◽  
Vol 3 (3) ◽  
pp. 343-347 ◽  
Author(s):  
K. M. Muditha Dassanayake ◽  
◽  
Masaomi Tsutsumi ◽  
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
High Performance ◽  
Worm Gear ◽  
Rotary Table ◽  
Positioning Accuracy ◽  
Roller Drive ◽  
Gear Mechanism ◽  
Accuracy And Repeatability

The high performance rotary tables are immense necessary part for the multi-axis machines. These rotary tables are yet in the developing stage. In this report, a rotary table driven by roller drive is introduced and the characteristics of that are discussed by comparing them with the characteristics of rotary table driven by worm gear mechanism. As the characteristics, the positioning accuracy and repeatability, frequency response, rotational fluctuations and influence of unbalance mass on motion are measured. According to the measured results, it can be said that the rotary table driven by roller drive shows high performances and therefore it can be said that this type of rotary tables are well suited for machine tool applications.

Motion Characteristics of High Performance Rotary Tables for CNC Machines

2008 ◽  
Author(s):  
K. M. Muditha Dassanayake ◽  
Masaomi Tsutsumi ◽  
Ryuta Sato ◽  
Hisayoshi Ito
Keyword(s):  
High Performance ◽  
Simulated Data ◽  
Friction Torque ◽  
Worm Gear ◽  
Torsional Stiffness ◽  
Rotary Table ◽  
Motion Characteristics ◽  
Accuracy And Repeatability ◽  
Better Than ◽  
Good Agreement

In this paper, the characteristics of two rotary tables driven by worm gear and roller gear cam are measured and compared. The positioning accuracy and repeatability as specified in ISO 230-2 are measured together with the rotational fluctuation, backlash, friction torque, frequency response of the systems and also the influence of unbalance mass on rotational motion. Two rotary encoders which were attached to motor and output axis were used for measurements. The motor, controller, and the rotary encoders were kept the same for both tables to ignore the effects of these units on results. Furthermore, the simulations were carried out by mathematical models which were proposed by two of the authors and the results were compared with measured results. From the simulation results, the torsional stiffness and friction torque were identified and also compared. The results show that the measured and simulated data have a good agreement and therefore it can be said that the identified parameters from simulations are accurate. The result shows that the performances of the rotary table driven by roller gear cam is better than that of rotary table driven by worm gear.

Comparison of Motion Characteristics of High Performance CNC Rotary Tables

2010 ◽  
Author(s):  
Muditha K. M. Dassanayake ◽  
Masaomi Tsutsumi
Keyword(s):  
High Performance ◽  
Closed Loop ◽  
Friction Torque ◽  
Step Response ◽  
Rotary Table ◽  
Direct Drive ◽  
Drive Motor ◽  
Fluctuation Frequency ◽  
Motion Characteristics ◽  
Accuracy And Repeatability

In this paper, the motion performances of the two rotary tables which are driven by roller gear cam and direct drive motor are measured and compared. The table with roller gear cam was controlled in semi-closed loop and full-closed loop methods while the other was controlled only in full-closed loop method. In the measurements, the positioning accuracy and repeatability, rotational fluctuation, frequency response, step response and etc of the systems were measured. All these tests were carried out without any kind of compensation methods such as pitch error or cogging torque compensation etc. Three rotary encoders for rotary table with roller gear cam and one rotary encoder for rotary table with direct drive motor were used for measurements. Furthermore, the simulations were carried out by mathematical models and the results were compared with measured results. The comparison shows that the measured and simulated results have a good agreement. From the simulation results, the friction torque was identified and also compared. The results imply that though both the tables show high performances, the performances of the rotary table driven by roller gear cam are comparatively higher than that of rotary table driven by direct drive motor.

High Performance Motion Control of Rotary Table for 5-Axis Machining Centers

2007 ◽  
Vol 1 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Ryuta Sato ◽  
◽  
Masaomi Tsutsumi
Keyword(s):  
Motion Control ◽  
High Performance ◽  
Rotational Velocity ◽  
Worm Gear ◽  
Rotary Table ◽  
Rotary Axes ◽  
Rotary Axis ◽  
Gear Backlash ◽  
Measurement Delay ◽  
Set Up

We discuss motion control techniques of rotary tables for 5-axis machining centers. Three translational axes and two rotary ones are controlled simultaneously in the machining of complex shapes such as impellers. A tilting rotary table powered by a worm gear is generally used as the rotary axes for 5-axis machining centers, and various causes of inaccuracy exist in the rotary axes. In this study, we clarified three causes of inaccuracy exists in the rotary axis: rotational fluctuation in the worm gear, backlash, and measurement delay of rotary encoder for feedback. Motor torque saturation of the rotary axis also causes a problem when rotational velocity is changed rapidly. Based upon investigated results, we propose compensators for improving synchronous accuracy. We avoid torque saturation in the rotary axis through acceleration-deceleration design. To verify the effectiveness of the proposed compensators, we applied them to an experimental set-up including a rotary axis. As the results of experiments, it is clarified that the proposed compensators improve the synchronous accuracy of translational and rotary axes.

High Performance Milling Torque Sensor

1998 ◽  
Vol 120 (3) ◽  
pp. 504-514 ◽  
Author(s):  
D. A. Smith ◽  
S. Smith ◽  
J. Tlusty
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
Strain Gage ◽  
Digital Signal Processor ◽  
High Performance ◽  
Torsional Stiffness ◽  
Torque Sensor ◽  
Sensing Element ◽  
Combined System ◽  
Face Mill

Machine tool supervision and control algorithms require reliable and effective sensor signals to operate properly. In effort to satisfy this need, a high stiffness, wide bandwidth torque sensor for use in milling has been developed which directly measures the torque applied to a milling cutter during operation. The sensor is designed to fit between the tool and holder on conventional tooling with very little effect on the cutting process. The sensor is strain gage based and provides a virtually distortionless torque measurement over a bandwidth from DC to 2000 Hz when using a 100 mm diameter face mill on a commercial machining center. High torsional stiffness was achieved to provide a wide measurement bandwidth while allowing enough material strain, in the sensing element, to provide sufficient resolution of the milling torque. The radial stiffness of the sensor was also designed to be large enough not to compromise the stability and accuracy of the machine tool. The sensor is designed to house the critical electronic components which amplify the small voltage strain gage signal and convert the measurement into digital samples. These samples are continuously transmitted from the rotating spindle, in all positions, to a stationary receiver. Because the sensor is part of a structural system which also includes the spindle, tool holder and tool, the frequency response has distortions associated with the vibrational modes of the system. In order to obtain a wide undistorted bandwidth, a compensation filter having the reciprocal response of the sensor has been designed and implemented on a digital signal processor (DSP). The combined system of the sensor cascaded with the DSP provides a flat magnitude and linear phase frequency response.

A Low-Cost and High-Resolution Micro Machine Tool With Toggle-Based Mechanism

2014 ◽  
Author(s):  
Shih-Ming Wang ◽  
Chih-Peng Yang ◽  
Zhe-Zhi Ye ◽  
Chuntai Yen
Keyword(s):  
Machine Tool ◽  
Low Cost ◽  
Dynamic Compliance ◽  
Cnc Machine ◽  
Positioning Accuracy ◽  
New Type ◽  
Weight Structure ◽  
Micro Machine ◽  
Fine Resolution ◽  
Micro Machine Tool

The products of 3C, bioscience, medical industry, and aerospace industry are becoming smaller and smaller. The components of the products are made of various materials with complex 3D shapes requiring high accuracy in their dimensions and contours. An accurate micro-/meso-scale CNC machine tool is an essential part of this technology. A new type of CNC micro machine tool with a toggle-like mechanism having the characteristics of low-cost and fine-resolution was developed. With geometric reduction principle, the machine can provide finer feed resolution and better positioning accuracy without using high-end driving components and controller. The kinematics model and characteristics of the machine were derived and analyzed. Modal analysis and dynamic compliance analysis were employed to design a light-weight structure with good stiffness. The accuracy calibration results showed the machine can reach a positioning accuracy of 500 nm. Prototype of the machine was built, and furthermore some micro machining examples were demonstrated in this paper.

scholarly journals Study on Small-size Hourglass Worm Gear with a High Performance (4th Report)

2002 ◽  
Vol 2002 (0) ◽  
pp. 135-136
Author(s):  
ZI HE LU ◽  
MINORU MAKI ◽  
TAKAYYUKI SUYAMA ◽  
TAKESHI SAITOH
Keyword(s):  
High Performance ◽  
Worm Gear

On-Machine Metrology System Using Confocal Chromatic Probe and Motion Error Correction for Ultra-Precision Machine Tool

2020 ◽  
Author(s):  
Hao Duan ◽  
Shinya Morita ◽  
Takuya Hosobata ◽  
Masahiro Takeda ◽  
Yutaka Yamagata
Keyword(s):  
Machine Tool ◽  
Free Form ◽  
Reference Curve ◽  
Optical Surface ◽  
Motion Error ◽  
Precision Machine ◽  
Ultra Precision ◽  
Axis Position ◽  
Form Deviation ◽  
Accuracy And Repeatability

Abstract Aspherical or free-form optical surface machining using an ultra-precision machine tool is a common and effective method in precision optics manufacturing. However, this method sometimes causes waviness due to the machine’s motion in mid-spatial frequency (MSF) form deviations. This waviness lowers the quality of the optical surface. To address this problem, we use the waviness of the axial displacement of the ultra-precision machine tool. The waviness is obtained by a non-contact on-machine metrology (OMM) system that measures an optical flat as a correction reference curve, which is used to correct the surface of the workpiece to reduce the effect of waviness in advance. The OMM system consists of a displacement probe and a machine tool axis position capture device. The probe system uses a confocal chromatic probe on an ultra-precision machine tool to evaluate the form deviation of the workpiece with 1 nm resolution. The axis position capture system uses a signal branch circuit of linear scale on each axis from the ultra-precision machine tool. The OMM system is tested in terms of accuracy and repeatability. In comparison to the results of the shaper cutting of an oxygen-free copper (OFC) workpiece with feed-forward correction, we were able to reduce the profile error from 125.3 nm to 42.1 nm in p-v (peak to valley) and eventually also reduced the waviness.

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