Gear Inspection Research Articles

A machine vision algorithm for quality control inspection of gears

Quality control has become a priority in the inspection processes of industrial manufacturing of gears. Due to the advancement of technology and the realizations of Industry 4.0, smart factories demand high precision and accuracy in the measurements and inspection of industrial gears. Machine vision technology provides image-based inspection and analysis for such demanding applications. With the use of software, sensors, cameras, and robot guidance, such integrated systems can be realized. The aim of this paper is to deploy an improved machine vision application to determine the precise measurement of industrial gears, at subpixel level, with the potential to improve quality control, reduce downtime, and optimize the inspection process. A machine vision application (Vision2D) has been developed to acquire and analyze captured images to implement the process of measurement and inspection. Firstly, a very minimum calibration error of 0.06 pixel was obtained after calibration. The calibrated vision system was verified by measuring a ground-truth sample gear in a Coordinate Measuring Machine (CMM), using the parameter generated as the nominal value of the outer diameter. A methodical study of the global uncertainty associated with the process is carried out in order to know better the admissible zone for accepting gears. After that, the proposed system analyzed twelve other samples with a nominal tolerance threshold of ± 0.020 mm. Amongst the gears inspected, the Vision2D application identified eight gears which are accepted and four bad gears which are rejected. The inspection result demonstrates an improvement in the algorithm of the Vision2D system application when compared with the previous existing algorithms.

고속 임베디드 기어 검사 시스템을 위한 불량 검출 알고리즘 FPGA 가속화 연구

Gear defects are detected by PC-based machine vision systems for high-speed and high-accuracy inspection. Implementing gear inspection on an embedded platform can enhance power efficiency and lower cost but generally has poorer calculation performance than a PC-based system. Therefore, this paper proposes a power-efficient and high-performance embedded gear inspection system that incorporates accelerated gear inspection algorithms running on an FPGA/ARM SoC software-hardware codesign. First, image processing algorithms for detecting defective gears were proposed. Then, the calculation time for each function was analyzed to find the sources of calculation bottlenecks. The selected heavy load functions such as the minimal enclosing circle function were accelerated by implementing the algorithms to run on FPGA hardware using optimization directives. A prototype of the inspection system was designed to inspect defect gear samples created by a 3D printer. Test results show that through the HW/SW codesign for the FPGA SoC (Xilinx ZCU102), a preprocessing function, such as morphology, and the overall defect inspection process run up to 49 times and 1.98 times faster, respectively, than a software implementation on the same embedded CPU processor.

Double Flank Gear Roll Inspection of Spur Gears Manufactured using Fused Deposition Modeling

The paper presents an experimental study that has as main objective the evaluation of the integration capacity of the spur gears obtained by FDM in high precision mechanisms. The development of precision mechanical systems required the use of the additive layer manufacturing technology in order to manufacture the gears that have specific particularities for the applications in which gears are integrated. Take these aspects into consideration, the paper presents the results achieved by testing on a ZWP-06 machine the gears obtained by fused deposition modeling technology. Gears were obtained on an Anet A2, semiprofessional 3D printer. To obtain a superior quality of toothed wheels, both process parameters: the material properties, and the features of the 3D printer were taken into account. The results, obtained from the test, revealed the level of influence of the execution parameters of the toothed wheels by FDM on their quality. The correlation of the process parameters remains the most important aspect for obtaining components with a high accuracy class, which complies with the resistance standards under the conditions of a shorter execution time.

Laser line triangulation for fast 3D measurements on large gears

The causes of geometrical deviations from the production process and the prediction of application properties, such as noise behavior, wear or material fatigue, are only possible by having detailed information about the gear geometry. The gold standard for the gear quality inspection is represented by dimensional measurements with a tactile sensor system. As a result for industrial applications, the slow serial measurement leads to the compromise of a random inspection of the gear geometry. For the purpose of a faster and more extensive surface acquisition, a laser line triangulation sensor is investigated providing 1280 points at a line width of 25 mm with up to 200 lines/s. The results at the tooth of a large cylindrical involute gear with a pitch circle diameter of 922 mm and a face width of 246 mm show the qualification for fast three-dimensional measurements of the convex and reflective surface. The detection of the complete profile line at once is possible. It is shown that the measurement deviation of laser line triangulation can be minimized by increasing the dynamic threshold. The measurement deviations amount to ± 8.2 µm and can be attributed to random and systematic errors. Compared to the standard gear inspection, an acceleration factor of 5700 was attained. An optical scanning of the complete tooth flank provides the prerequisite for an identification of surface defects in the form of breakouts and blemish.

Gear Inspection in Record Time

Gear Inspection in Record Time

TESTING METHOD OF GEAR MEASURING INSTRUMENTS

Gears are used in many machineries and it is important to make their accuracy higher and improve their performance. Gear vibration and noise is a severe problem for automobiles. It is influenced by micron-meter-order accuracy of tooth of gear and therefore inspection of gears is necessary using gear measuring instruments. Test of accuracy of gear measuring instruments is important for quality control. In most cases, a gear measuring instrument is calibrated by an artifact with higher accuracy than the calibrated instrument. However, conventional artifacts have a problem in accuracy because of its complicated form. In addition, various testing methods exist depending on measuring machine companies because there is no standard on testing method of gear measuring instrument. This paper introduces a new evaluation method of involute artifact, newly developed artifacts, a developed testing method of gear measuring instruments, and Japanese Industrial Standards concerning them.

Multidimensional Tensor-Based Inductive Thermography With Multiple Physical Fields for Offshore Wind Turbine Gear Inspection

Condition monitoring (CM), fault diagnosis (FD), and nondestructive testing (NDT) are currently considered crucial means to increase the reliability and availability of wind turbines. Many research works have focused on CM and FD for different components of wind turbine. Gear is typically used in a wind turbine. There is insufficient space to locate the sensors for long-term monitoring of fatigue state of gear, thus, offline inspection using NDT in both manufacturing and maintenance processes are critically important. This paper proposes an inductive thermography method for gear inspection. The ability to track the properties variation in gear such as electrical conductivity, magnetic permeability, and thermal conductivity has promising potential for the evaluation of material state undertaken by contact fatigue. Conventional thermography characterization methods are built based on single physical field analysis such as heat conduction or in-plane eddy current field. This study develops a physics-based multidimensional spatial-transient-stage tensor model to describe the thermo optical flow pattern for evaluating the contact fatigue damage. A helical gear with different cycles of contact fatigue tests was investigated and the proposed method was verified. It indicates that the proposed methods are effective tool for gear inspection and fatigue evaluation, which is important for early warning and condition-based maintenance.

A Bevel Gear Quality Inspection System Based on Multi-Camera Vision Technology.

Surface defect detection and dimension measurement of automotive bevel gears by manual inspection are costly, inefficient, low speed and low accuracy. In order to solve these problems, a synthetic bevel gear quality inspection system based on multi-camera vision technology is developed. The system can detect surface defects and measure gear dimensions simultaneously. Three efficient algorithms named Neighborhood Average Difference (NAD), Circle Approximation Method (CAM) and Fast Rotation-Position (FRP) are proposed. The system can detect knock damage, cracks, scratches, dents, gibbosity or repeated cutting of the spline, etc. The smallest detectable defect is 0.4 mm × 0.4 mm and the precision of dimension measurement is about 40–50 μm. One inspection process takes no more than 1.3 s. Both precision and speed meet the requirements of real-time online inspection in bevel gear production.

Design and Implementation of Electric Steering Gear Inspection System for Unmanned Aerial Vehicles Based on Virtual Instruments

A kind of UAV electric servo detection system based on Virtual Instrument is designed in this paper, including the hardware platform based on PC-DAQ virtual instrument architecture and the software platform based on LabVIEW function, structure and system implementation methods. The function, structure and system implementation method of software platform is also described. The gear limits checking, zero testing, time domain characteristics test results showed that the system achieves testing requirements well, and can complete detection of electric steering gear automatically, fast, easy and accurate.

A Concept of in-Process Measurement System for Spline Forming

Abstract In the paper a possibility of in-process inspection of gear and spline shafts during forming was discussed. Different methods of forming toothed elements were discussed as well as the other technologies were mentioned. Coordinate measurement technique as a way of post process inspection was presented. However, it is not possible to use it for checking features during forming process. To do it different sensors were used and their combinations were described.

Bending Fatigue Failure of a Helical Pinion Bevel Gear

The analysis of pinion gear damage operated in a tube coiler machine gearbox was investigated. Visual inspection, SEM fractographic analysis, and metallographic evaluation are employed as the principal analytical techniques for the investigation. Fractographic observations indicated the occurrence of bending fatigue started at the maximum load surface of the gear teeth, known as active flank, and propagated to the opposite area resulting in catastrophic tooth fracture. Unbalanced stress conditions led to the consecutive damage and fracture of adjacent teeth resulting in machine interruption and immediate replacement of the gear system. The multiple fatigue crack initiation sites suggest significant stress concentration probably caused likely by gear misalignment. Metallographic evaluation revealed an entirely heat-treated gear microstructure consisted of tempered martensite free from microstructural abnormality that could be associated to the failure. Regular gear inspection and system alignment checks together with the consideration of increasing surface hardness, through selected surface strengthening procedures, are suggested as further corrective actions to minimize similar failures and machine downtime in the future.

Super-Large Gear Measurement Using Laser Tracker and CMM

As general methods can no longer be used to measure super-large gears, their manufacturing accuracy, performance and quality cant be guaranteed. In this paper, after introducing the characteristics, measuring requirement and the state of arts of inspection of super-large gears, a laser tracker and CMM based measuring technology, proposed by Shi, was presented, and the key techniques were discussed. By taking full advantage of the characteristics of a laser tracker and a coordinate measuring apparatus, the super-large gears positioning problem, which was to determine the relationship between the instrument and workpeice, was solved. Thus, the gears profile, helix, and topology error etc. could be measured. Experiments have been carried out to verify the effectiveness of the method. The results showed that the proposed method could be used to measure super-large gears with the diameters up to 10m.

머신비전을 이용한 타원형 기어 검사 시스템에 관한 연구

타원형 기어는 오발 유량계에 사용되는 특수기어로써 타원형 모양에 의해 생긴 공간으로 물을 흘려보내 계측한다. 본 연구의 목적은 타원형 기어의 가공정도를 판단하고 불량을 가려내는 시스템을 머신비전을 이용하여 개발하는 것이다. 각종 산업분야에서 자동화가 확산되면서 머신미전의 수요는 늘고 있으며 업계전반의 생산공정 중 검사 공정에서 빼놓을 수 없는 인자가 되었다. 하지만 머신비전을 이용한 기어측정은 기어의 형상이 복잡하다는 이유로 잘 사용되지 않고 있다. 본 연구에서는 머신비전을 이용한 검사 프로그램으로 타원형 기어의 측정이 가능함을 보였으며 본 연구에서 설계한 타원형 기어의 가공정도를 판단할 수 있었다.

Effect of the Impact Load on the Main Welding Outer Cylinder of Large Aircraft Landing Gear

Analysis about the cause of the main failure and the forces of the main welding outer cylinder of the recent large aircraft landing gear were given. The impact load for main welding outer cylinder in the process of the taking off and landing was calculated of 580MPa. Finite element model of the main welding outer cylinder was then established and the influence of the impact loading to the main welding outer cylinder was analyzed. The results showed that crack was most likely take place on the top of the outer cylinder, and then on the two welds. The crack expanded in an S shape. This study could provide an important basis for the safety of the aircraft landing gear inspection and service life prediction.

Inspection of Surface Rolled Sintered Gears using Eddy-Current Sensor

A inspection regarding surface rolled sintered gears performed in-line is required. The authors have proposed a inspection method using an eddy-current sensor. Since this method uses the eddy-current, a inspection of gears is possible in a nondestructive manner with a short time. In this paper, in order to perform a inspection using an eddy-current sensor, porosity, residual stress, resistivity, and relative permeability of the surface rolled sintered steel are measured. Furthermore, output voltage characteristics of surface rolled sintered gears that the amounts of surface rolling differ are measured. As a result, it is clarified that porosity and resistivity decrease and relative permeability increase with increasing residual stress. Moreover, it is clarified that over surface rolled gear can be judged with output voltage.

3-D Precise Modeling of Modified Gear Based on Visual Basic

The design process of involute spur modified gear is very complicated, especially the accurate mapping of the tooth profile curve, in which it must demands specialized knowledge to designers by procedural programming method. According to the tooth profile curve calculation method as well as its relationship with cutter, get the curve equation of involute and tooth root transition curve. Compiled each the program of the calculating curve of tooth profile by Visual Basic, and built the precision model of involute spur modification gear based on the SolidWorks through the secondary development. This paper realizes the parametric precise modeling of modified gear and improves the accuracy and automation level of the design of gear. It has important significance to the dynamic simulation of gear and interference inspection as well as finite element analysis.

Automatic Inspection System of Small Plastic Gears Based on Machine Vision

Small plastic gear is generally made by injection molding.But the injection molding process and mold have problems with missing tooth, shrink, more material, less material and inaccurate roundness and so on. Furthermore, using manual inspection will appear phenomenon of low efficiency, false detection and leak detection. To solve these problems, this paper introduces an automatic inspection system of small plastic gears based on machine vision. The system consists of feeding and sorting machine control system and machine vision inspection system of the gear defects. Mechanical control use digital servo control technology to achieve automatic nesting, feeding, positioning of gear workpiece, and depend on the inspection result of machine vision system to sort. After acquired gear image through a camera, Machine vision system uses median filtering, binarization, edge detection algorithms to process image. Then the system adopts template matching algorithm to obtain the inspection result and send the result to the sorting controller, which achieve automatic smart inspection of gear. The automatic inspection system has accurate, efficient, intelligent and other advantages.

High‐Speed Scanning of Critical Structures in Aviation Using Coordinate Measurement Machine and the Laser Ultrasonic

Aviation is one of the know-how spheres containing a great deal of responsible sub-assemblies, in this case landing gear. The necessity for reducing production cycle times while achieving better quality compels metrologists to look for new and improved ways to perform inspection of critical structures. This article describes the ability to determine the shape deviation and location of defects in landing gear using coordinate measuring machines and laser ultrasonic with high-speed scanning. A nondestructive test is the basis for monitoring microcrack and corrosion propagation in the context of a damage-tolerant design approach. This article presents an overview of the basics and of the various metrological aspects of coordinate measurement and a nondestructive testing method in terms of high-speed scanning. The new test method (laser ultrasonic) promises to produce the necessary increase in inspection quality, but this is limited by the wide range of materials, geometries, and structure aeronautic parts used. A technique combining laser ultrasonic and F-SAFT (Fourier-Synthetic Aperture Focusing Technique) processing has been proposed for the detection of small defects buried in landing gear. The experimental results of landing gear inspection are also presented.

Computer vision algorithms for measurement and inspection of spur gears

Precision measurement of gears plays a vital role in gear measurement and inspection. The current methods of gear measurement are either time consuming or expensive. In addition, no single measurement method is available and capable of accurately measuring all gear parameters while significantly reducing the measurement time. The aim of this paper is to utilize the computer vision technology to develop a non-contact and rapid measurement system capable of measuring and inspecting most of spur gear parameters with an appropriate accuracy. A vision system has been established and used to capture images for gears to be measured or inspected. A software (named GearVision) has been especially developed in-house using Microsoft Visual C++ to analyze the captured images and to perform the measurement and inspection processes. The introduced vision system has been calibrated for metric units then it was verified by measuring two sample gears and comparing the calculated parameters with the actual values of gear parameters. The maximum differences between the calculated parameters and the design values were ±0.101 mm for a spur gear with 156 mm outside diameter. For small gears, higher accuracy could be obtained and as well as small difference.

Laser Interferometric Measuring Method of Involute Artifact and Stabilization of Measurement

Vibration and noise are serious problems with involute spur and helical gears used, e.g., in drivetrains of vehicles such as automobiles. The gear tooth flank form of micrometer order markedly affects gear vibration and noise; therefore, the tooth flank form quality must be strictly controlled to maximize gear performance. Tooth profile measuring machines used in calibration for form error inspection of involute gears usually use an involute artifact, which itself must be calibrated highly accurately. However, it is typically difficult for current tooth profile measuring machine using contact stylus to calibrate the involute artifact with a high accuracy while satisfying traceability to a national standard. A highly precise and traceable measuring technology for the involute artifact is therefore required. The direct measurement of the involute artifact we propose uses a laser interferometer, whose measurement stability is confirmed in experiments measuring the detailed form of an involute tooth flank.