scholarly journals The method for evaluation errors of automated measurements of base tangent length by three-axis indicator on five-axis CNC machine

2021 ◽  
pp. 35-43
Author(s):  
D. T. Safarov ◽  
◽  
A. G. Kondrashov ◽  
Keyword(s):  
Statistical Methods ◽  
Systematic Errors ◽  
Random Errors ◽  
Cnc Machine ◽  
Cnc Machines ◽  
Automated Measurements ◽  
Periodic Monitoring ◽  
End Mills ◽  
Systematic And Random Errors ◽  
Five Axis

The article provides an overview of studies of various errors in the process of measuring parts with three-coordinate probes on CNC machines. The paper considers a method for estimating systematic and random errors in the process of measuring the length of the base tangent using control maps and probabilistic and statistical methods for processing multiple repeated inputs of a three-coordinate indicator to the measured side surfaces of the wheel teeth. The method is designed to assess the acceptability of the measurement process by technologists and adjusters. The data of experimental estimation of random and systematic errors of measurement of the length of the base tangent on a five-coordinate CNC machine with a three-coordinate indicator of Mahr are presented. The obtained error values for the five-axis machine under study allow us to measure the length of the base tangent for the purposes of periodic monitoring and adjustment of the machine when processing oblique cylindrical wheels with universal disk or end mills

Statistics and parallaxes

1978 ◽  
Vol 48 ◽  
pp. 7-29
Author(s):  
T. E. Lutz
Keyword(s):  
Experimental Design ◽  
Statistical Methods ◽  
Review Paper ◽  
Systematic Errors ◽  
Past Experience ◽  
Random Errors ◽  
Trigonometric Parallaxes ◽  
Systematic And Random Errors

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.

A Reliable and Efficient Approach to Numerically Controlled Programming Optimization for Multiple Largest Tools Cutting Blisks Patch by Patch in the Blisks' Four-Axis Rough Machining

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Zhiyong Chang ◽  
Jinan Wen ◽  
Zezhong C. Chen ◽  
Dinghua Zhang
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Surface Patch ◽  
Free Form ◽  
Cnc Machine ◽  
Rough Machining ◽  
Cnc Machines ◽  
End Mills ◽  
Five Axis ◽  
Free Form Surfaces

As an important component of gas turbine engines, a blisk (or an axial compressor) is complex in shape. The pressure and suction surfaces of the blisk blades are designed with free-form surfaces, and the space (or the channel) between two adjacent blades varies significantly. Thus, some blade patches can be machined with large-diameter cutters, and some patches have to be cut with small-diameter cutters. Usually, the blisk's material is high-strength stainless steel, titanium alloy, or difficult-to-cut material. The cutting force and temperature in roughing the blisks are high, and thus, the machine tool should be rigid and the cutters should be as large as possible. Therefore, the best industrial practice of rough-machining the blisks is to use multiple largest solid and indexable end-mills to cut them patch by patch on a four-axis computer numerically controlled (CNC) machine. The reasons are (a) four-axis CNC machines are more rigid than five-axis CNC machines, (b) multiple largest cutters are used for higher cutting speeds and feed rates and for less machining time and longer tool life, and (c) if indexable end-mills can be used, the tooling costs are further reduced. For the blisk finishing, a small cutter is often used on a five-axis CNC machine, which is not a topic of this work. However, due to complex shape of the blades, it is quite difficult to automatically optimize the blade surface partition so that each surface patch can be cut with a largest cutter in four-axis blisk rough machining. In the conventional way, numerically controlled (NC) programmers often employ small-diameter solid end-mills and plan their paths to cut the blades layer by layer in four-axis milling. Unfortunately, the machining efficiency of this way is low, and the end-mills wear out quickly. This work establishes a theoretical and completed solution. A simplified optimization model of the largest allowable diameter of the theoretical cutter at a cutter contact (CC) point is established, and an efficient and reliable solver is proposed. The blade surfaces are automated partitioned for largest cutters to the surfaces patch by patch in four-axis rough machining. This approach is efficient and reliable, and it is viable in theory and practical in industry.

Discretizors and Interpolators for Five-Axis CNC Machines

1999 ◽  
Vol 122 (1) ◽  
pp. 191-197 ◽  
Author(s):  
Radha Sarma ◽  
Aarthi Rao
Keyword(s):  
Discrete Time ◽  
Sampling Period ◽  
Cnc Machine ◽  
Time Intervals ◽  
New Techniques ◽  
Cnc Machines ◽  
Complex Curves ◽  
Computer Numerically Controlled ◽  
Five Axis

Discretization and interpolation of curves are two frequently adopted practices when machining complex curves using computer numerically controlled (CNC) machines. Both practices stem from the need to sample curves at discrete time intervals corresponding to the sampling period of the CNC machine. This paper proposes new techniques for discretization and interpolation that account for the change of tool orientations in five-axis machining. First, the method for discretization proposed in this paper is based on sampling the curves such that specified contour, feedrate, and orientation errors are not exceeded. Second, the interpolator proposed in this paper will be able to avoid excessive angular speeds arising from sampling the curves based on the feedrate alone. [S1087-1357(00)01401-5]

scholarly journals Measurement of total normal length of helical cylindrical gears by three-axis indicator on five-axis CNC machine

2021 ◽  
pp. 13-19
Author(s):  
A. G. Kondrashov ◽  
◽  
D. T. Safarov ◽  
Keyword(s):  
Single Point ◽  
Measurement Data ◽  
Gear Wheel ◽  
Linear Measurement ◽  
Point Method ◽  
Small Scale ◽  
Cnc Machine ◽  
End Mills ◽  
Measuring Machine ◽  
Five Axis

The article discusses a method for automated measurement of the length of the general normal of a helical cylindrical wheel, which allows to obtain its exact value without removing the part after gear processing with disk or end mills. The measurements are carried out by means of an automated supply of a three-coordinate linear measurement indicator to the calculated measurement points. The formulas for calculating the length of the general normal are given, which allow calculating the value of the length of the general normal and the correction value of the CNC gear ring processing program for two and one-point measurement schemes with the indicator. The use of the two-point method of measuring the length of the general normal with a three-coordinate indicator made it possible to measure the length of the general normal without removing the processed gear wheel from the mandrel, the single-point method completely eliminates the possibility of adjustment defects and reduces the complexity of carrying out machine changeovers in the mode of single and small-scale processing of gears. Comparison of gear measurement data with the three-coordinate indicator Mahr and a specialized CNC gear measuring machine give similar values and confirm the possibility of using the developed scheme to measure the length of the common normal

Accuracy Enhancement of Alignment for Five-Axis CNC Machine Tools through Touch Trigger Probes

2011 ◽  
Vol 381 ◽  
pp. 11-15
Author(s):  
Sheng Bao ◽  
Fu Zhang ◽  
Xi Zhang
Keyword(s):  
Reference Frame ◽  
Machine Tools ◽  
Measuring Method ◽  
Least Square ◽  
Cnc Machine Tools ◽  
Random Errors ◽  
Cnc Machine ◽  
Method Of Least Square ◽  
Touch Trigger Probe ◽  
Five Axis

The random errors exist in measuring with touch trigger probe. These errors are directly introduced into workpiece coordinate system with conventional alignment method. An enhanced measuring method is proposed in this paper to improve the accuracy of alignment for five-axis CNC machine tools. By using the method of least square, an error reference frame is constructed, and the relationship between the alignment parameters and the error reference frame is derived. An example of aircraft structural parts is presented to validate the presented method.

Evaluation of IRD-WIM-5000 — a Canadian weigh-in-motion system

1990 ◽  
Vol 17 (4) ◽  
pp. 514-520 ◽  
Author(s):  
Satish C. Sharma ◽  
George Stamatinos ◽  
John Wyatt
Keyword(s):  
Systematic Errors ◽  
Study Data ◽  
Random Errors ◽  
Motion System ◽  
Planning And Design ◽  
Dynamic Weight ◽  
Weigh In Motion ◽  
Highway Planning ◽  
Systematic And Random Errors ◽  
Weight Data

The analysis presented in this paper deals with the accuracy of a weigh-in-motion (WIM) system installed on Trans-Canada Highway west of Regina. Spot speed data collected by the WIM system are compared with the measurements taken by a radar meter; the WIM data on axle spacing are compared with data obtained by manual measurements; and the dynamic weight data gathered by the WIM system are evaluated against static weights. The following conclusions can be made from this study: The WIM system under investigation provides accurate data for spot speed and axle spacing. The study data for 88 trucks indicate that the dynamic weights recorded by the WIM system may contain high magnitudes of both systematic and random errors. However, the results of analysis presented indicate that a proper calibration of the system can reduce the systematic errors to a large extent and produce results that may be satisfactory for a number of highway planning and design functions. Key words: axle spacing, dynamic weight, highways, static weight, traffic studies.

scholarly journals Study of Machining of Gears with Regular and Modified Outline Using CNC Machine Tools

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2913
Author(s):  
Rafał Gołębski ◽  
Piotr Boral
Keyword(s):  
Machine Tools ◽  
Coordinate Measuring Machine ◽  
Optical Microscope ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cylindrical Gears ◽  
Measuring Machine ◽  
Five Axis

Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

Finite Element Analysis for Machine Joint

2010 ◽  
Vol 26-28 ◽  
pp. 198-203
Author(s):  
Tie Neng Guo ◽  
Ling Li ◽  
Li Gang Cai ◽  
Zhi Feng Liu
Keyword(s):  
Dynamic Characteristic ◽  
Maximum Error ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Element Analysis ◽  
Mechanical Joint ◽  
Result Show ◽  
Joint Element ◽  
Stiffness And Damping ◽  
Five Axis

The stiffness and damping of mechanical joint are modeled by the zero thickness joint interfaces theory. The method is applied to analyze the dynamic characteristic of the gantry frame in a five axis turning-milling compound CNC machine tool. The model test is carried out in the gantry frame, and the maximum error of the first sixth mode is 5.63%. The experimental and analysis result show the zeros thickness joint element can provide an effective method to model the machine joint and predict the dynamic characteristic of the assembled structure.

Sensitivity Analysis of Geometric Errors for Five-Axis CNC Machine Tool Based on Multi-Body System Theory

2012 ◽  
Vol 271-272 ◽  
pp. 493-497
Author(s):  
Wei Qing Wang ◽  
Huan Qin Wu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Cnc Machine ◽  
Multi Body ◽  
Five Axis

Abstract: In order to determine that the effect of geometric error to the machining accuracy is an important premise for the error compensation, a sensitivity analysis method of geometric error is presented based on multi-body system theory in this paper. An accuracy model of five-axis machine tool is established based on multi-body system theory, and with 37 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The analysis result shows that the presented method can identify the important geometric errors having large influence on volumetric error of machine tool and is of help to improve the accuracy of machine tool economically.

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