Measuring and testing – Sampler – sample handling – etc. – Analyzer supplier
Reexamination Certificate
2002-10-30
2004-05-25
Raevis, Robert (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
Analyzer supplier
Reexamination Certificate
active
06739207
ABSTRACT:
The present application hereby claims priority under 35 U.S.C. §119 on Swedish patent application number SE 0202011-3 filed Jun. 28, 2002, the entire contents of which are hereby incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a device and a method for combined selection of a sample, grinding of the selected sample and presentation of the sample for an analysis system.
BACKGROUND OF THE INVENTION
A device according to above is previously known. Such a device is used to facilitate spectrometric analysis of a product sample, consisting of e.g. pasta, grain, other feedstuff, or industrial material components, which should be grinded before the analysis. The selection of the sample may be made directly from a process line (On-Line analysis sampling). Common types of spectrometric analyses which may be used are Near Infrared Reflection (NIR) and Near Infrared Transmission (NIT) analysis.
The previously known device comprises a combined sample container and grinding chamber. In the grinding chamber, a plunger is arranged which encompasses a rotatable and axially movable knife rotor. The axis of the knife rotor extends parallell to the axis of the grinding chamber. To the knife rotor, a number of knives are attached.
The grinding chamber of the previously known device is arranged on an external rotor which is positioned in a stator. The stator is in turn arranged where the samples are to be selected. On the stator is a presentation matrix arranged, into which the sample may be pressed out from the grinding chamber for analysis through a window of the presentation matrix.
When using the previously known device, the sample is first taken from the process line to the grinding chamber through an open end of the chamber. Then the rotor is turned to a position where the open end of the grinding chamber is covered by the stator, and the knife rotor is moved backwards and forwards in the chamber for grinding the sample. After that, the rotor is turned further to an analysis position where the grinded sample is pressed by the plunger into the presentation matrix for analysis. After the analysis, the sample is pressed out from the device through the presentation matrix.
The previously known device allows sample selection, grinding and presentation for an analysis system to be combined in one single unit. This gives a lot of advantages compared to other prior art, where the product sample is taken through several part processes in different units in order to be analysed. Examples of problems known from other prior art which may be eliminated by using the previously known device are: contamination of samples, cleaning up remains from earlier samples in several units, and expensive and complicated transport systems to transport samples from the process line to an analysis central and back again.
However, the previously known device has also a few disadvantages. The construction with rotor and stator, for shifting between positions for sample selection, grinding and analysis, is relatively complicated and bulky.
The previously known device may also be utilized without the rotor and stator by enclosing the grinding chamber manually with a lid. The lid may after grinding optionally be replaced by a presentation matrix for analysis of the sample. A disadvantage with this solution is, however, that it is manual and therefore only is practically usable for occasional samples.
SUMMARY OF THE INVENTION
An object of an embodiment of the present invention is to provide an improved device and method for combined selection of a sample, grinding of the selected sample and presentation of the sample for an analysis system.
Another object of an embodiment of the present invention is to further develop the basic idea of the previously known device described above into a simplifyed and rationalized device.
Preferably, an embodiment of the present invention shall also enable improved repeatability of the analysis conditions from one sample analysis to another.
For achieving at least some of these and other objects, a device and a method according to an embodiment of the invention are provided.
More particularly, according to an embodiment of the invention, a device for combined selection of a sample, grinding of the selected sample and presentation of the sample for an analysis system, comprises a grinding chamber, a grinding means for grinding said sample in said grinding chamber, and a pressing means for compression of said sample in and output of said sample from said grinding chamber. The device is characterized in that it further comprises a first chamber opening for input of said sample into said grinding chamber, and a second chamber opening for said output of said sample from said grinding chamber, wherein said first chamber opening is separate from said second chamber opening. By having one chamber opening for input of the sample and another chamber opening for output of the sample, the need for turning the grinding chamber and thereby also the need for a rotor and a stator is eliminated.
By eliminating the need for turning the grinding chamber, another advantage is also gained. Turning of the grinding chamber increases the segregation between small and large particles of the sample material, which results in that the presented sample becomes inhomogeneous. This deteriorates the analysis result, wherefore elimination of the need for turning the grinding chamber is advantageous.
As defined herein, “grinding” means transformation of the material into smaller particles. Hence, grinding also includes atomization or pulverization of a solid material, as well as coarse grinding. The grinding may be accomplished by means of cutting, milling, or some other process.
In one embodiment of the invention, said second chamber opening is arranged to be closed during said compression of said sample. This makes it possible to achieve controllable compression of the sample for analysis. Controllable compression makes it possible to accomplish similar analysis conditions from one sample analysis to another. This improves the repeatability and comparability between different sample analyses.
Especially when spectrum analysis, such as NIR or NIT analysis, is used, it is important to control the compression of the sample, since different compressions result in different spectra. The only interesting parameter for spectral analysis is the spectra of the sample material, wherefore the influence or variation of all other parameters, including compression of the sample, particle size (degree of grinding of the material), air pressure, heat, moisture etc, must be reduced as much as possible. The previously known device described above comprises a presentation matrix with a smaller diameter then the grinding chamber of the device. A sample is pressed from the grinding chamber into this presentation matrix, whereby a certain small compression of the sample for analysis is achieved. However, a drawback with this solution is that the presentation matrix is open in the outer end, wherefore controllable compression of the sample is not possible.
In another embodiment of the invention, the device is arranged so that said sample is inside said grinding chamber during said presentation of said sample for the analysis system. This eliminates the need for a separate presentation matrix, which is used in the previously known device, and contributes to further decrease of the above mentioned segregation of the sample particles.
In another embodiment of the invention, said second chamber opening is arranged to be closed during said presentation of said sample for the analysis system. This is another feature which adds to decreased segregation of the sample particles and repeatable analysis conditions.
In another embodiment, said first chamber opening is arranged to be closed during said compression of said sample. Depending on the actual construction of the grinding chamber, a closed first chamber opening during the compression further facilitates controllable compression.
In yet ano
Foss Tecator AB
Harness Dickey & Pierce PLC
Raevis Robert
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