Reduction of machining errors of a three-axis machine tool by on-machine measurement and error compensation system
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Machine tool
Artifact (error)
Cube (algebra)
Backlash is a need for proper gear mesh but also a defect if not controlled closely. Few studies have focused on controlling backlash with some mechanical solutions that can be applied. Few other studies have shown interest in estimation of minimum / maximum variable backlash. The operating backlash of meshing gears is affected by many factors among which runouts, pitch errors and tooth thicknesses are the three most pronounced manufacturing errors. All these three parameters are the measurable ones once the gears are manufactured. Center distance and phasing of meshing gears are the examples of assembly errors which may affect the operating backlash. A software has been developed to predict likely maximum and minimum backlash of a gear pair selected arbitrarily and assembled together. For the validation of software predictions an experimental setup is needed for backlash measurements. Thus, a special test rig is designed and constructed for experimental measurements of the operating backlash under some manufacturing and assembly errors of a gear pair. Good agreements have been achieved between backlash predictions and measurements thus validating the in-house prepared software for backlash calculations.
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A survey was presented that generalizes studies in the area of backlash nonlinear control in recent years.Different backlash models and compensation approaches for backlash nonlinearity were analyzed,and applications of various methods in the field of backlash nonlinearity control were introduced for systems with backlash located in various positions.Some remarks on the issue were given.
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This paper does systematic research on the principle of backlash compensation about CNC machine tools.The backlash of an XK714 grinder at Xaxis direction is measured by use of dial indicator.After the backlash is compensated,the machine backlash error is eliminated and the accuracy of machine movement is improved.
Machine tool
Pulverizer
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Abstract Harmonic drive transmissions are widely used in robotics, space manipulation systems because of their excellent mechanical properties including low backlash, high speed reduction ratio and compact size. Analytical investigation and modeling of backlash and hysteresis for harmonic drive are reported, but no thorough understanding of backlash as well as its attributes is available in literature. In this research, the experimental and analytical studies of backlash are conducted. First, the definition of backlash according to China National Standard (CNS) is given, which also matches the requirements in application. A dedicated apparatus was designed to measure the backlash. The results of this paper offer an insight into backlash of harmonic drive and the results are valuable in the mechanical design of harmonic drive gears as well as the dynamic modeling and precision control of harmonic drive systems.
Harmonic drive
Harmonic
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In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect talc calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments. for 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. And a generalized volumetric error model formulator for three-axis machine tools was developed, which allowed us to formulate machine tool synthesis error models far all possible machine tool configurations only with machine tool topology information. Based on these volumetric error model and model formulator, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.
Machine tool
Position (finance)
Position error
Work space
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In this paper, a nonlinear control system considering the uncertainties of the backlash of nonlinear plants is proposed. The uncertainties of the backlash of nonlinear plants are included in thresholds of backlash. Firstly, a backlash model with uncertain thresholds is proposed. Secondly, a robust nonlinear control system is designed. Finally, the effectiveness of the proposed system is confirmed by simulations.
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The global warming backlash, the managed care backlash, the Bush backlash, the corporate backlash, the 9/11 backlash, the Obama backlash, the Clinton backlash, the Foreign Intelligence Surveillance Act (FISA) bill backlash, the antigay backlash, the immigration backlash, the backlashes against globalization, student testing, the social, economic, and political progress of Latinos, African Americans, and Asian Americans, and, central to this “Critical Perspectives,” the backlash against the feminist movement—these were just some of the many politically related backlashes that appeared when I performed a general Google search of the words: “backlash” and “politics” in July of 2008.
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Sphere artifact is for evaluation of pitch-measuring accuracy of gear-measuring instruments (GMIs). The sphere artifact is composed of equally spaced spheres around an axis. A GMI measures a pitch of the spheres instead of gear teeth. The GMI is evaluated by comparing the measurement result and a calibrated pitch value. The difference between measurement value and the calibration value includes three error components; (i) GMI errors (ii) a measurement uncertainty for the calibration value (iii) setting errors of the sphere artifact to the GMI. This paper repots the degree to which setting error affects the pitch-measuring accuracy. It can be seen that the setting error for an inclination error is negligible small; on the other hand the setting error for an eccentricity error affects the pitch-measuring accuracy.
Artifact (error)
Eccentricity (behavior)
Accuracy and precision
Measuring instrument
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ABSTRACT This paper addresses the issue of automatic identification of backlash in robot transmissions. Traditionally, the backlash is measured manually either by the transmission manufacturer or the robot manufacturer. Before the robot can be delivered to the end-customer, the backlash must be within specified tolerances. For robots with motor measurements only, backlash is an example of an uncontrollable behaviour which directly affects the absolute accuracy of the robot’s tool-centrepoint. Even if we do not attempt to bring backlash under real-time control in this paper, we will describe a method to automatically identify/estimate the backlash in the robot transmissions from torque and position measurements. Hence, only the transmissions that do not meet the backlash requirements in the automatic tests need to be checked and adjusted manually.
Identification
Position (finance)
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