Device for counting inclusions in a liquid metal bath using ultrasound
a technology of liquid metal bath and inclusions, applied in the direction of geological measurements, using reradiation, and analysing fluids using sonic/ultrasonic/infrasonic waves, etc., can solve the problem of not being able to see inclusions in large quantities, the probability of inclusions being very low, and the inclusion method not working for large quantities
Inactive Publication Date: 2004-10-14
PECHINEY RHENALU & ALUMINUM PECHINEY
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- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
This method provides accurate and reliable counting and sizing of inclusions, particularly large ones, across a significant volume of liquid metal, ensuring precise quality control without polluting the metal or affecting production processes.
Problems solved by technology
Considering that the number density of the inclusions to be measured is low (of the order of 1 ppm), that there are few large inclusions, and that the latter are the most harmful inclusions when a thin plate is required, it can be seen that, with this type of sampling method, there is a risk that the results obtained may not be really representative and that the probability of seeing the said inclusions is very low.
Another method called LIMCA (Liquid Metal Cleanliness Analysis) is also known that essentially consists of continuously sampling the liquid metal through a small orifice and measuring the variation in the resistance of the liquid metal at each passage of an inclusion; but this method does not work for large inclusions (in other words inclusions larger than about 100 .mu.m).
Therefore it appears difficult to use one of these methods to measure the amount of progress that can still be done towards eliminating inclusions, and particularly large inclusions.
It is also mentioned that the number of inclusions at a certain depth in the tested volume can be counted by the probes, by counting the number of peaks due to reflections of signal on inclusions using a computer, and that it is difficult to make measurements for all the metal contained in the crucible.
These processes are only capable of analysing a restricted volume of liquid metal, and usually only provide approximate global information about inclusions so that it is only possible to say if the liquid metal is clean or dirty, and do not provide any precise information about the number and size of inclusions.
This type of method cannot be used industrially.
It is not realistic to plan to use pure metal in an industrial installation without the risk of it getting dirty, and consequently the calibration measurement would be biased; furthermore, the introduction of particles could pollute and severely disturb the industrial manufacturing cycle.
All this makes the method unreliable and difficult to perform.
Method used
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[0036] A characterization was made on an experimental casting line and the quality of liquid metal produced by two furnaces was evaluated. One of the furnaces was clean, and the other was contaminated by inclusions. Table 1 contains the number of peaks corresponding to inclusions with equivalent sizes larger than 300 and 500 .mu.m, as estimated from the probed volume (about 5% of the cast volume) and expressed as a number per kg.
1 TABLE 1 Contaminated Clean furnace furnace Inclusions with 0.40 0.03 equivalent size larger than 300 .mu.m Inclusions with 0.12 0.00 equivalent size larger than 500 .mu.m
Advantages of the Invention
[0037] The process is particularly useful for making a precise count of the largest inclusions, typically larger than 100 .mu.m, which are usually present in small numbers and are therefore difficult to identify using other analysis methods, but which are the most harmful, and for determining their size.
[0038] This invention provides a useful method of analysing ...
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Abstract
Apparatus for displaying, measuring the size of and counting individual inclusions in suspension in moving liquid metal using an ultrasound sensor including emission device for emitting ultrasound beam pulses and at least one reception device for detecting reflected ultrasound beam pulses. The apparatus also includes an echo acquisition and processing device for reflected ultrasound beams received by the at least one reception means, a display device for displaying echos as images of inclusions, an image analysis device to count and measure inclusions based on the displayed images, and at least one control reflector having predetermined dimensions and geometry stable over time and which can be selectively placed in path defined by the ultrasound beam pulses. The control reflector enables calibration of the apparatus.
Description
TECHNICAL DOMAIN[0001] This invention relates to an improved ultrasound process and device for counting liquid and / or solid inclusions present in a liquid metal flow usually in a vessel or better in a trough, and for measuring their size. The invention is particularly applicable to aluminium, magnesium or their alloys.STATE OF THE ART[0002] It is extremely important to be able to precisely control the quality of inclusions when casting liquid aluminium; the quality of thin plates and the proportion put into scrap depends on this quality of inclusions, particularly for plates made for the manufacture of closed drink or aerosol can receptacles.[0003] Generally, the inclusion quality of a liquid metal is determined using the number density and size of inclusions contained in the liquid metal.[0004] Characterization methods usually involve taking samples of at most about 0.01% of the liquid metal. Considering that the number density of the inclusions to be measured is low (of the order ...
Claims
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IPC IPC(8): G01N15/02G01B17/00G01N29/02G01N29/032G01N29/24G01N29/30G01N33/20G01S15/89
CPCG01N29/032G01N29/0645G01N29/2456G01N29/30G01N33/206G01N2291/02416G01N2291/0252G01N2291/102G01N33/205
Inventor MULLER, JEANBRUN, PIERRE LEODIEVRE, THIERRY
Owner PECHINEY RHENALU & ALUMINUM PECHINEY