IMPROVED SAMPLE CHAMBER FOR MOLTEN METAL

Abstract

A sample chamber for taking samples from a molten metal bath. The chamber comprises a flat cover plate and a housing, wherein the flat cover plate and housing are assembled together to form a sample cavity. The housing comprises an immersion face and an opposing end face, a top face and a bottom face. The housing comprises a first opening in the immersion face, and a second opening in another face. The top face has at least one indentation, comprising a distribution segment, a ventilation segment and an analysis segment and wherein the analysis segment is bounded by an analysis plane AP. The distribution segment and the ventilation segment are in a direction from the top face to an opposite face of the housing and the maximum and the minimum cross-sectional area of the analysis segment do not deviate from each other by more than 20%.

Claims

1. A sample chamber for taking samples from a molten metal bath, particularly a molten steel bath, comprising a flat cover plate and a housing, wherein the flat cover plate and the housing are configured to be assembled together along an analysis plane AP to form a sample cavity; wherein the housing comprises an immersion face and an opposing end face, a top face and a bottom face, the top face and the bottom face extending between the immersion face and the opposing end face; wherein the housing comprises a first opening in the immersion face, and a second opening in another face; wherein the top face has at least one indentation; wherein the indentation comprises a distribution segment, a ventilation segment and an analysis segment and wherein the analysis segment is bounded by the analysis plane AP; wherein the distribution segment, the analysis segment and the ventilation segment are in flow communication with each other and with the first and the second opening of the housing, wherein: the distribution segment and the ventilation segment are arranged below the analysis segment in a direction from the top face to the bottom face; and, the maximum and the minimum cross-sectional area of the analysis segment perpendicular to a central longitudinal axis X of the housing do not deviate from each other by more than 20%.

2. The sample chamber according to claim 1, wherein a central axis of the distribution segment is arranged with an angle between 45 to 90 to the central longitudinal axis X of the housing.

3. The sample chamber according to claim 1, wherein a central axis of the ventilation segment is arranged with an angle between 45 to 90 to the central longitudinal axis X of the housing.

4. The sample chamber according to claim 1, wherein the cross-sectional area of the analysis segment does not decrease after 50% of the length of the analysis segment.

5. The sample chamber according to claim 1, wherein the maximum and the minimum cross-sectional area of the analysis segment do not deviate from each other.

6. The sample chamber according to claim 1, wherein the cross-sectional area of the analysis segment is between 2.5 and 10 times the cross-sectional area of the ventilation zone parallel to the analysis plane AP.

7. The sample chamber according to claim 1, wherein the width of the analysis segment is constant in the direction of the central longitudinal axis X of the housing.

8. The sample chamber according to claim 1, wherein the analysis segment has a length between 20 and 50 mm.

9. The sample chamber according to claim 1, wherein the ventilation segment is positioned in a distance smaller than 20% of the length of the analysis segment from the end of the analysis segment.

10. The sample chamber according to claim 1, wherein the width of the analysis segment is higher than the width of the ventilation segment.

11. The sample chamber according to claim 1, wherein the top face comprises a single indentation.

12. The sample chamber according to claim 1, wherein the assembled sample chamber comprises only two openings.

13. A sampler, comprising a sample chamber according to claim 1 and a carrier tube adapted to accommodate at least parts of the sample chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0110] The following schematic drawings show aspects of the invention for improving the understanding of the invention in connection with some exemplary illustrations, wherein

[0111] FIG. 1 shows a sampler for taking samples from a molten metal bath;

[0112] FIG. 2 shows the housing and the cover plate of the sample chamber hold together by a clamp;

[0113] FIG. 3 shows a housing in different views;

[0114] FIG. 4 shows side views of an assembled sample chamber;

[0115] FIG. 5 shows the hollowed parts of the housing of the sample chamber in more detail;

[0116] FIG. 6 shows the sample chamber with different possible cross-sectional geometries of the analysis segment in front view of the housing.

[0117] FIG. 1 shows a sampler 1 for taking samples from a molten metal bath. The sampler 1 is suitable for immersion in and sampling of molten metal. The shown sampler 1 comprises a measuring head 2 which can be made of resin bonded silica sand. The measuring head 2 is supported on a carrier tube 3 which can be a paper carrier tube. In use, a probe holder or lance (not shown) is preferably inserted into the interior volume of the carrier tube 3 to provide the mechanical action necessary to submerse the measuring head 2 below the surface of a bath of molten metal in the immersion direction I.

[0118] The measuring head 2 comprises the sample chamber 20 for collection and retrieval of a sample of molten metal. The sample chamber 20 as shown is composed of a housing 22 and a flat cover plate 23 as shown in more detail in FIG. 2 from a front view perspective.

[0119] The measuring head 2 has a first end and an opposing second end. The first end of the measuring head 2 corresponds to an immersion end of the measuring head 4. The second end of the measuring head is configured to face a lance or probe holder. Also, the housing 22 of the sample chamber 20 has a first end 30 and an opposing second end 31. The first end of the housing 30 corresponds to an immersion face of the sample chamber 20. It will be understood by those skilled in the art that the phrase immersion end means the end of the assembly, respective the sampler, which is first immersed into molten metal. At the first end of the housing 30 an inflow conduit 5 is attached, which is received by a first opening 34. The inflow conduit 5 enables the flow of molten metal from the molten metal bath into the sample cavity 21 (not visible in the shown view of FIG. 1).

[0120] In use, the measuring head 2 is immersed in the immersion direction I into a hot metal bath. Thus, the inflow direction of the molten metal when introduced into the sample chamber 20 and its cavity 21 is in a direction opposite the immersion direction I parallel to the longitudinal axis X of the sample cavity 21.

[0121] The inflow conduit 5 is covered by a first protection cap 6. The first protection cap 6 is preferably made of metal, and more preferably steel. A second protection cap 7, in turn, covers (and more specifically encompasses) the first protection cap 6. The second protection cap 7 is attached to the measuring head 2. Preferably, the second protection cap 7 is made of metal, and more preferably steel.

[0122] The sample chamber 20 can be purged and pressurized by inert gas which is supplied via a coupler (not shown) connected to a second opening in the housing towards the inflow conduit 5. A skilled person will understand that the purging with inert gas is only necessary for certain applications. After the measuring head 2 is immersed below the surface of the hot metal bath, the second protection cap 7 melts due to the heat of the hot metal, thereby exposing the first protection cap 6 to the hot metal. Subsequently, the first protection cap 6 also melts, thereby placing the sample chamber 20 in fluid communication with the hot metal bath. Hot metal then enters the sample chamber, particularly via the first opening 34 from the immersion end 30 to the second end 31 while gas is exhausted out of the sample chamber cavity 21 through the second opening 35.

[0123] When the molten metal freezes in the sample cavity 21, the solidified metal sample is formed inseparably from the housing 22. The measuring head 2 is easily fractured allowing removal of the sampling chamber 20 from the carrier tube 3. If present, a clip 8 holding together the sample chamber 20 is removed. Unlike conventional sampling devices, the sample remains attached to the sample housing 22. Therefore, the term sample, when referring herein to the metal coupon delivered to the OES, refers to the inseparable combination of the retrieved solidified sample and the sample housing 22.

[0124] The housing 22 and the cover plate 23 of the sample chamber 20 can be held together by a clip or clamp 8, as also shown in FIG. 2, with a compression force sufficient to resist a tendency of the two parts to separate due to the force of molten metal flowing into and filling the sample cavity 21 and the force during the purging phase prior to the filling with the sample. The clip 8 can preferably be made from metal. FIG. 2 shows a front view of a sample chamber, i.e. the immersion face 30 and the first opening 34 of a housing 22. In the configuration illustrated in FIG. 2 A, a clip 8 is arranged mainly on the cover plate 23. The housing 22 comprises recesses 10 with which the clip can interact. The clip 8 can also be arranged sideways as shown in FIG. 2 B.

[0125] For practical purposes of assembly, the flat cover plate 23 can have approximately the same width and length as the housing 22. A first face of the cover plate 9 is configured to face the housing 22. A sealing member (now shown) can be provided on the first face of the cover plate 9 so as to be positioned between the housing 22 and cover plate 23 in the assembled configuration of the sample chamber 20

[0126] FIG. 3 shows a housing 22 according to embodiments of the invention in different views. In particular, FIG. 3 A shows a cut through partial view, while FIG. 3 B shows a top view on the top face 32 of a housing 22 with the indentation 40. Segments positioned below the top face and thus not visible in the presented view are indicated by grey lines. The top face 32 shown in the figures is an analysis face, meaning it is the geometric side of the housing 22 in which the sample is collected, and which is thus configured to be positioned face down upon the stage of optical emission spectrometer during analysis. During analysis, inert gas is purged into the spark chamber of the spectrometer so that leaks between the sample to be analyzed and the spectrometer stage cannot be tolerated. Furthermore, the analysis surface of the solidified metal sample which abuts the cover plate helps to close the opening of the OES. A complete filling of this surface is therefore required to fully close the spectrometer opening. In particular, the front of the molten metal entering the sample cavity should at least reach the ventilation segment prior to freezing.

[0127] The top face 32 comprises the indentation 40 which forms at least a part of the sample cavity 21 of the sample chamber 20. As illustrated, the top face 32 extends between the immersion end or face 30 and the opposing end or face of the housing 31. FIG. 3 A and B illustrate, that the top face 32 is hollowed out to form different segments of the sample cavity 21 for receiving the molten metal, the collection of molten metal sample and the ventilation of the cavity. The indentation 40 is defined by an elongated shape.

[0128] FIG. 3 B also illustrates where the longitudinal axis X of the housing and the width W and length L of the indentation 40 are to be found. Also visible is the hollowed face of the housing 41, comprising two more indentations below the plane of the top face. In the shown embodiment, the hollow part of the housing 22 comprises two additional segments, namely a distribution segment 43 and a coupler segment 46. It is to be noted, that both segments 43 and 46 are not visible in the portion of the housing shown in FIG. 3 A. As illustrated, the hollowed face 41 comprises all parts of the housing within the indentation 40 as visible in the shown view. In the illustrated embodiment, the opposing ends of the indentation 40 (i.e., the leading end and the trailing end in terms of the immersion direction I) are rounded for ease of machining. However, it will be understood by those skilled in the art, that the ends may have any shape. In the embodiment of the invention shown in FIG. 3, the top face of the housing 32 comprises a rim 11. Such a rim can enhance the sealing with the cover plate, especially in cases where an additional sealing element is also part of the sample chamber assembly.

[0129] FIG. 4 shows side views of an assembled sample chamber according to embodiments of the invention. In FIG. 4 A, the sample chamber 20 is shown in assembled configuration with an inflow conduit 5. The cover plate 23 is arranged on the top face 32 of the housing 22 along the analysis plane AP closing the hollow parts of the housing, thereby building the sample cavity 21. In the shown configuration, an inflow conduit 5 is in communication with an inflow segment 42 of the sample cavity 21. FIG. 4 B shows an alternative embodiment of the invention with a de-oxidising element 12 arranged within the inflow conduit 5.

[0130] FIG. 5 shows different configurations of the hollow volume, i.e. the sample cavity, of a housing 22 in more detail, illustrating the configurations of the different segments of the sample cavity 21 with respect to each other for certain embodiments. An upper part of the indentation confined by the analysis plane AP forms the analysis segment 44. The analysis segment 44 fully overlies a distribution segment 43 and a ventilation segment 45. The aforementioned three segments form a u-shaped indentation, which is in flow connection to the first opening 34, optional via an inflow segment 42. The analysis segment 44 as shown has a uniform depth in direction of the central longitudinal axis X. The ventilation segment 45 can further be connected to a coupler segment 46 positioned at the opposite side of the housing as illustrated in FIG. 5 A. In FIG. 5 B an alternative configuration is shown, in which the ventilation segment 45 is directly connected to a second opening 35 in the face of the housing opposite to the top face 32, i.e. the bottom face 33. In both embodiments, the ventilation segment 45 is positioned flush with the end of the analysis segment 47.

[0131] The analysis segment 44 is confined by the analysis plane AP on one side and a bottom plane BP on its opposite side, both planes are shown as dashed lines in FIG. 5. The bottom plane BP is partly an imaginary plane extending the plane of the hollowed face across the distribution segment 43 and the ventilation segment 45 along the central longitudinal axis X. The central axis of the distribution segment D as well as the central axis of the ventilation segment V are arranged perpendicular to the central longitudinal axis X and the analysis plane AP in both embodiments shown.

[0132] The hollowed face of the housing 22 comprises several parts as also indicated in the figures. A first part HF.sub.D which forms the bottom boundary of the distribution segment 43, a second part HF.sub.A which forms the bottom boundary of the analysis segment 44, and a third part HF.sub.V which forms the bottom boundary of the ventilation segment 45. In the illustrated configuration in FIG. 5 B, the hollowed face only comprises two segments.

[0133] Preferably, when a sample is taken, the molten metal fully fills and freezes in the analysis segment 44 against the cover plate 23, in particular along the analysis plane AP. The shown configuration of the segments of the hollowed parts of the housing ensures that these requirements are fulfilled. The minimum deviation of the cross-section of the analysis segment along its length together with the positioning of the ventilation segment completely below this segment ensures the complete filling before the molten metal front entering the sample chamber begins to solidify.

[0134] FIG. 6 shows embodiments of the sample chamber with different possible cross-sectional geometries of the analysis segment in front view of the housing 22 i.e. in the direction along the longitudinal axis X and the related parameters used to describe the analysis segment. Also shown is the cover plate 23. It is to be noted, that the shown dimensions are not necessarily drawn to scale. In FIG. 6 A, the cross-section of the analysis segment 44 has a rectangular shape. On the upper side, it is enclosed by the cover plate 23, which also defines the analysis plane AP. On the opposite side, the segment is bounded by the bottom plane BP. As a skilled person will understand, the cross-sectional area is determined by the width W and depth D of the segment. FIG. 6 B shows an analysis segment 44 with a triangular shaped bottom plane, whereas FIG. 6 C shows a convex shaped cross section of the analysis segment 44.

[0135] The features disclosed in the claims, the specification, and the drawings maybe essential for different embodiments of the claimed invention, both separately or in any combination with each other.

REFERENCE SIGNS

[0136] 1 Sampler [0137] 2 Measuring Head [0138] 3 Carrier Tube [0139] 4 Immersion End of Measuring Head [0140] 5 Inflow Conduit [0141] 6 First Protection Cap [0142] 7 Second Protection Cap [0143] 8 Clip [0144] 9 First Face of Cover Plate [0145] 10 Recesses [0146] 11 Rim [0147] 12 De-Oxidizing Element [0148] 20 Sample Chamber [0149] 21 Sample Cavity [0150] 22 Housing [0151] 23 Cover plate [0152] 30 Immersion End/Face of Housing [0153] 31 Opposing End/Face of Housing [0154] 32 Top Face of Housing [0155] 33 Bottom Face of Housing [0156] 34 First Opening of Housing [0157] 35 Second Opening of Housing [0158] 40 Indentation in Top Face [0159] 41 Hollowed Face [0160] 42 Inflow Segment [0161] 43 Distribution Segment [0162] 44 Analysis Segment [0163] 45 Ventilation Segment [0164] 46 Coupler Segment [0165] 47 End of Analysis Segment [0166] I Immersion Direction [0167] X Central Longitudinal Axis [0168] AP Analysis Plane [0169] D Central Axis of Distribution Segment [0170] V Central axis of Ventilation Segment [0171] HF.sub.D First Part of Hollowed Face [0172] HF.sub.A Second Part of Hollowed Face [0173] HF.sub.V Third Part of Hollowed Face