Utrasonic and Magnetic Inspection of Railway Wheels

Automated System for Utrasonic Inspection of Railway Wheels

System overview

The STARMANS company has been developing the equipment for ultrasonic inspection of railway wheels since 1998. Several different conceptions and arrangements were developed " starting from simple two-channel system for testing bandages, through the system for US testing of wheels in horizontal position, up to the last, most efficient system for US testing of wheels in vertical position.

The testing system consists of rigid mechanic frame with immersion tank. The wheel is fed in vertical position into the tank by means of a crane (manipulator).

Specifications of wheels are as follows:

• Wheel dimensions ? 650 - 1300 mm
• Hub dimensions ? 100 - 350 mm
• Diaphragm dimensions ? 200 - 1000
• Diaphragm width 100 - 160 mm
• Hub width 130 - 240 mm
• Max. weight 1000 kg

Transducers are moved away to the safe parking position during feeding and removing the wheel. Linear guides of transducers are installed above the water level, enabling testing the wheel hub in axial direction, wheel diaphragm in axial direction and wheel rim in both axial and radial directions.

The system is modular, probe holders allow to use immersion transducers or transducers with gap coupling. The control system allows testing using all transducers simultaneously and allows setting up the sections to be tested.

Graphic records include actual requirements and can be modified according to eventual additional requirements at any time, without changing the basic program, by editing of graphs structure. Graphs enable documenting the position, diameter, area, depth of detected defects, loss of back wall echo in the C-scan, with displaying sections of measurement from all transducers.

There is a possibility of saving and documenting of A-scan in any point, or to save A-scan according to prescribed criterion in the defect location.

Summary

The ultrasonic inspection system is equipped with modern computerized devices enabling fully automated operation without presence of operator:

• automatic loading and unloading of wheels
• short time for inspection of one wheel
• multi-channel system with fully independent ultrasonic channels " possibility of extension and upgrades
• high repeatability and reproducibility of test results
• simplicity of control and setting up the system via user oriented software
• possibility of remote diagnostic of the system
• immediate documenting and archiving of the test results, including the data transfer to the company central information system
• completing the documentation after inspection " generating reports for separate wheels and for full batch/order
• quick information about accepted and rejected wheels
• statistic processing of the test results acc. to pre-defined criteria
• saving of all parameters and functions of testing for simple use in future or for checks and re-inspections

Automated System for Magnetic Particle Inspection of Railway Wheels

High safety standards required in the management of railroad lines, demand the inspection of train wheels directly after production in order to detect the presence of surface cracks that could seriously affect the integrity of the train, and therefore passengers safety.

System overview

During the last year, STARMANS company have been developing an automatic system for surface defect detection on train wheels. The main goal was to develop the highly reliable system based on image processing algorithms that gives an warning of surface flaws to prevent possible future accidents.

The system is based on magnetic inspection where the train wheel is put into the magnetic field and the cracks cause a magnetic stray field. By this technique the cracks are visible and they can be easily recorded using high speed digital camera, also developed in STARMANS company.

In the developing stage, we simulated the magnetic field to find out the optimal position of train wheel in magnetic field for the best defect visibility.

During the magnetic inspection of train wheel, the surface is scanned by digital camera. The recorded pictures are promptly evaluated of our proposed image processing algorithm. Whole surface and different sizes of train wheels can be inspected.

The proposed algorithms can be briefly described in three main steps:

1. Noise reduction - The picture is corrupted with relatively high noise level and detection process is more difficult " hardware part

2. Defect detection - Defects have to be recognized from scratchy surface of train wheel. Only the flaws have to be detected " software part

Both noise reduction and detection algorithms are based on simple mathematical equations and implemented in our developed digital camera. It means that the pictures are processed on-line, during inspection.

3. Defect classification - The defects most commonly occurring on train wheels are similar to straight line. With proposed algorithm we are able to recognize the flaw shape and consequently classified as a linear object in various slope or as an object with distinct shape (drop of magnetic particles).

Summary

The presented automated system for defect detection on train wheels was completely developed in STARMANS company. With this system it is possible to detect the surface flaws on train wheels. The digital camera with adequate resolution was developed for the surface scanning and proposed digital image processing algorithms are implemented both in hardware and software parts. In case of flaw detection, it is possible to detect the flaws in length of 1 mm and thickness (width) of 0.3 mm. The proposed system is fully automatic and it is able to successfully detect and classified flaws. The system can be modified for special desired industrial applications.