Instrument for evaluating storage object in glass melting tank and method for evaluating storage object in glass melting tank

Abstract

To provide a technique for more accurately evaluating a storage object in a glass melting tank.SOLUTION: An instrument for evaluating a storage object in a glass melting tank includes: a glass melting tank for storing molten glass obtained by melting a glass raw material and a glass raw material layer covering the upper part of the molten glass; and a rod-like main body inserted into the molten glass through the glass raw material layer. A trap part for trapping the molten glass is provided on the peripheral surface of the rod-like main body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an instrument for evaluating the contents of a glass melting tank and a method for evaluating the contents of a glass melting tank.

Background Art

[0002] In a glass melting apparatus, a technique for evaluating the state of the contents contained in a glass melting tank is known. For example, in Patent Document 1, in a cold top type glass melting tank, the range of the base surface of the molten glass to which the glass raw material is supplied is periodically photographed from above to obtain an image, and based on the gradation value of the image, the state of the cold top (batch blanket) is evaluated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 also describes evaluating the thickness of the cold top, but the evaluation specifically remains at evaluating differences in thickness by region, temporal changes in thickness, etc. With the technique described in Patent Document 1, for example, the actual thickness (absolute value of the thickness) of the cold top cannot be measured.

[0005] Also, as another method for evaluating the contents of the glass melting tank, a method of inserting a rod-shaped instrument from above the contents, attaching the molten glass in the glass melting tank, and pulling it out is also conceivable. Since the uppermost position of the molten glass deposit on the rod-shaped instrument corresponds to the lower end of the cold top (the boundary position between the cold top and the molten glass), if the position corresponding to the upper end of the cold top in the state where the instrument is inserted is also recorded, the thickness of the cold top can be measured. However, when pulling out the rod-shaped instrument upward, the instrument needs to pass through the cold top, which is a layer of powdery or granular glass raw material. Therefore, when the adhesion force of the molten glass deposit to the instrument is weak, etc., when the instrument moves upward, the molten glass deposit may be trapped by the glass raw material of the cold top and detached from the peripheral surface of the instrument or shifted downward from the initially attached position. In that case, the thickness measurement of the cold top etc. cannot be performed or cannot be performed accurately. Therefore, there is a need for a technology that can more accurately evaluate the contents of the glass melting tank, for example, measure the thickness of the cold top.

[0006] One aspect of the present disclosure provides a technology that can more accurately evaluate the contents of a glass melting tank.

Means for Solving the Problems

[0007] One aspect of the present disclosure is an instrument for evaluating the contents of a glass melting tank, wherein the glass melting tank contains molten glass obtained by melting a glass raw material and a layer of glass raw material covering the upper part of the molten glass, and includes a rod-shaped main body inserted into the molten glass through the layer of glass raw material, and a trap part for trapping the molten glass is provided on the peripheral surface of the rod-shaped main body.

Effects of the Invention

[0008] According to one aspect of the present disclosure, the contents of the glass melting tank can be more accurately evaluated.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0010] Hereinafter, specific embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description may be omitted.

[0011] First, referring to FIG. 1, the basic structure and usage of the instrument 10 according to an embodiment will be described. The glass melting tank 50 is a tank used in the glass melting process of the cold top method. As shown in FIG. 1, in the cold top method, the liquid surface LS of the molten glass G2 is covered by the layer G1 of the glass raw material introduced from above the glass melting tank 50. Then, the glass raw material is gradually melted by the heat transmitted from the molten glass G2. The melted molten glass G2 is taken out from the outlet 53 formed at the lower part of the wall of the glass melting tank 50. According to the cold top method, it is possible to suppress the escape of heat and / or volatile components from the molten glass G2, and the glass raw material can be efficiently melted. Note that the layer G1 of the glass raw material is also called a cold top or a batch blanket.

[0012] In the cold top method, the layer G1 of the glass raw material may cover preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more of the area of the liquid surface LS of the molten glass G2. Also, the layer G1 of the glass raw material may substantially cover the entire liquid surface LS of the molten glass G2. Further, the layer G1 of the glass raw material preferably has a maximum surface temperature of 500°C or less, and more preferably 350°C or less.

[0013] The glass raw material is prepared by mixing a plurality of types of materials and may contain a clarifying agent. The glass raw material may contain glass cullet obtained from discarded glass in order to recycle the glass. The glass raw material may be in powder form or in a state where the powdered raw material is granulated, that is, in granular form. The glass raw material is determined according to the desired composition of the glass and is not particularly limited. Specific examples of the glass include non-alkali glass, soda-lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, and the like.

[0014] The glass melting tank 50 is provided with heating means (not shown) for heating the molten glass G2, and may constitute a glass melting apparatus including the glass melting tank 50 and the heating means. The heating means may be, for example, an electrode capable of electrically heating the molten glass G2. When an electrode is provided in the glass melting tank 50, it is preferably provided on the bottom wall of the glass melting tank 50. In addition, the glass melting apparatus may be provided with heating means other than the electrode (such as a burner) instead of or in combination with the above-mentioned electrode for electric heating. Further, the glass melting apparatus is preferably an all-electric melting furnace having only the electrode as the heating means.

[0015] Note that the temperature of the molten glass G2 in the glass melting tank 50 can be 1000°C or higher and 1700°C or lower, although it depends on the type of the glass raw material. Also, the viscosity of the molten glass G2 is 10^1.5 (10 1.5 ) dPa·s or more and 10^4 (10 4 ) dPa·s or less.

[0016] An instrument (hereinafter also referred to as an evaluation instrument) 10 according to an embodiment is an instrument for evaluating the contents of the glass melting tank 50. The contents of the glass melting tank 50 include the molten glass G2 formed by melting the glass raw material and the layer G1 of the glass raw material covering the upper part of the molten glass G2. With the evaluation instrument 10 according to the present embodiment, at least one of the molten glass G2 and the layer G1 of the glass raw material can be evaluated. The state of the layer G1 of the glass raw material can be evaluated by the evaluation instrument 10. For example, the thickness of the layer G1 of the glass raw material can be measured. Measuring the thickness of the layer G1 of the glass raw material is particularly important for controlling the temperature of the molten glass G2. Also, the state of the molten glass G2 can be evaluated by sampling the molten glass G2 with the evaluation instrument 10. Thereby, for example, the temperature distribution in the depth direction of the molten glass G2 near the interface between the molten glass G2 and the layer G1 of the glass raw material can also be estimated.

[0017] As shown in FIG. 1, the evaluation instrument 10 may have a rod-shaped main body 11 which is a rod-shaped part, and a flange part 15 provided in the middle of the rod-shaped main body 11. The rod-shaped main body 11 may be a long cylindrical shape (hollow) or a long columnar shape (solid) as described later. The flange part 15 functions as a position mark on the rod-shaped main body 11, which is useful, for example, when measuring the thickness of the layer G1 of the glass raw material. In this specification, the direction along the axis of the rod-shaped main body 11 may be referred to as the axial direction, and the direction orthogonal to the axial direction (any direction along the plane orthogonal to the axial direction) may be referred to as the lateral direction. Further, among the lateral directions, the direction from the central axis of the rod-shaped main body 11 (illustrated by reference numeral CA in FIGS. 2 and later) to the outside of the rod-shaped main body 11 or the reverse direction may be referred to as the radial direction. Note that the flange part 15 is fixed to be relatively movable with respect to the rod-shaped main body 11, but it may be relatively movable along the axial direction of the rod-shaped main body 11.

[0018] When using the evaluation instrument 10, the distal end side 11a of the rod-shaped main body 11 is inserted into the container, and after maintaining the inserted state for a certain period of time, it is pulled out from the container. FIG. 1 shows the operation of inserting the rod-shaped main body 11 into the container (insertion operation) or the operation of pulling it out from the container (pulling out operation). The user of the evaluation instrument 10 can perform the insertion operation and the pulling out operation of the rod-shaped main body 11 by gripping the proximal end side 11b of the rod-shaped main body 11 and operating the evaluation instrument 10. In the form shown in FIG. 1, the rod-shaped main body 11 can be inserted into the inside of the melting tank 50 through an upper opening 61 formed in a deck 60 installed above the melting tank 50. Then, the distal end side 11a of the rod-shaped main body 11 is inserted into the container, more specifically, through the layer G1 of the glass raw material into the molten glass G2, and by maintaining that state for a certain period of time, the molten glass G2 adheres to the rod-shaped main body 11. Therefore, for example, the uppermost position of the deposit of the molten glass G2 may correspond to the position of the boundary between the layer G1 of the glass raw material and the molten glass G2 (the position of the liquid surface LS). Further, if the position corresponding to the upper end of the layer G1 of the glass raw material when the rod-shaped main body 11 is inserted into the container is recorded as a reference position, the thickness of the layer G1 of the glass raw material can be obtained by measuring the distance between the reference position and the position corresponding to the above boundary.

[0019] In the case of the evaluation instrument 10 provided with the flange portion 15 as shown in FIG. 1, the insertion operation of the rod-shaped main body 11 may be stopped when the lower surface of the flange portion 15 comes into contact with the upper end of the glass raw material layer G1. Thereby, since the position of the lower surface of the flange portion 15 becomes the reference position corresponding to the upper end of the glass raw material layer G1, it becomes easy to measure the thickness of the glass raw material layer G1. Instead of the flange portion 15, a mark recognizable by the user may be provided at the reference position on the rod-shaped main body 11. However, it is preferable that a plate-like member extending in a direction orthogonal to the rod-shaped main body 11 like the flange portion 15 is provided because the reference position is easy to recognize.

[0020] Here, when the adhesion force of the deposit of the molten glass G2 to the rod-shaped main body is small, when the rod-shaped main body passes through the glass raw material layer G1 during the pulling-out operation of the evaluation instrument, the deposit of the molten glass G2 receives resistance from the glass raw material and detaches from the peripheral surface of the rod-shaped main body or moves downward from the initially adhered position. In that case, it may not be possible to evaluate the contained material, or it may not be possible to perform the evaluation accurately. On the other hand, according to the present embodiment, a trap portion for trapping the molten glass G2 is provided on the peripheral surface of the rod-shaped main body 11. The trap portion will be further described with reference to FIGS. 2 to 4.

[0021] As shown in FIG. 2(a), a plurality of trap portions 2 are provided on the rod-shaped main body 11 along the axial direction. The trap portion 2 has a concave shape, specifically, a concave shape in the lateral direction, and has dimensions and a shape that allow the molten glass G2 to enter laterally and trap the molten glass G2.

[0022] Since the concave trap portion 2 is provided, when the rod-shaped body 11 is immersed in the molten glass G2, the molten glass G2 can enter along the lateral direction into the rod-shaped body 11. The molten glass G2 that has entered and adhered in this lateral direction is less likely to receive resistance from the glass raw material when the rod-shaped body 11 is pulled upward during the pulling operation of the evaluation instrument 10. Therefore, even after the evaluation instrument 10 is pulled out, the molten glass G2 that has entered the trap portion 2 is difficult to shift downward from the adhered position, so that the uppermost position of the molten glass G2 in the melting tank 50 can be accurately recognized. Further, among the adhered molten glass G2 (glass deposit), the portion that has entered the trap portion 2 functions as an anchor, so that the molten glass G2 adhered to the surface of the rod-shaped body 11 is also difficult to detach from the rod-shaped body 11.

[0023] In the embodiments shown in FIGS. 2 and 3, since the rod-shaped body 11 is a hollow body (cylindrical body), the trap portion 2 is formed as a hole 20 that penetrates the wall portion of the hollow body. The function of the hole 20 shown in FIGS. 2 and 3 will be further described with reference to FIG. 4. FIG. 4 shows an example of the state after the evaluation instrument 10 is inserted into and pulled out from the contents of the glass melting tank 50. FIG. 4(a) corresponds to FIG. 2(a), and FIG. 4(b) corresponds to FIG. 3(b). As shown in FIGS. 4(a) and (b), the molten glass G2 enters the hole 20 in the lateral direction. Also, depending on the inner diameter of the rod-shaped body 11, the viscosity of the molten glass G2, etc., the adhered molten glass G2 can also enter the inside of the rod-shaped body 11, which is a hollow body, and adhere to the inner wall of the hollow body beyond the lower edge 21 of the hole 20. Further, the molten glass G2 may partially fill the inside of the rod-shaped body 11, which is a hollow body. Note that the way the molten glass G2 enters the hole 20 shown in FIG. 4 is only an example, and depending on the type of the molten glass G2, the operating temperature of the melting tank 50, the time for immersing the evaluation instrument 10 in the molten glass G2, etc., various entry states different from the state shown in FIG. 4 can occur. For example, there may be a case where the molten glass G2 is filled between the lower end of one hole 20 and the upper end of the hole 20 adjacent below the said hole 20.

[0024] As shown in Fig. 4, since the molten glass G2 has entered the hole 20, when the rod-shaped main body 11 passes through the layer G1 of the glass raw material during the pulling operation of the evaluation instrument 10, even if it receives resistance from the glass raw material, the molten glass G2 is caught by the rod-shaped main body 11. Therefore, the relative axial movement between the rod-shaped main body 11 and the glass deposit is suppressed. Thus, even when passing through the layer G1 of the glass raw material, it is possible to prevent the molten glass G2 from detaching or moving from the attached position without succumbing to the resistance of the glass raw material. Further, in the present embodiment having the hole 20, since a relatively large amount of the molten glass G2 can be held at the lower end of the hole 20, it is preferable when sampling and analyzing the molten glass G2 for evaluation of the contained material.

[0025] In the example shown in Fig. 4(a), the molten glass G2 is attached to the inner wall of the second hole 20 from the top. Therefore, the upper end position H of the attached molten glass G2 max can be determined to be the uppermost position of the molten glass G2 in the melting tank 50, that is, the boundary position between the layer G1 of the glass raw material and the molten glass G2. And in the insertion operation of the evaluation instrument 10, when the rod-shaped main body 11 is inserted until the lower surface of the flange portion 15 reaches the upper end of the layer G1 of the glass raw material, the thickness of the layer G1 of the glass raw material is from the lower surface of the flange portion 15 to the upper end position H of the molten glass G2 max up to the distance T can be determined.

[0026] Note that, even in the case of a conventional instrument without the trap portion 2, for example, an instrument with a smooth peripheral surface of a rod-shaped body, if the molten glass G2 can be strongly baked onto the rod-shaped body with the rod-shaped body inserted, the glass deposits are less likely to detach from the rod-shaped body during the pulling operation. To facilitate the baking of the molten glass G2 onto the peripheral surface of the rod-shaped body, for example, it is conceivable to maintain the state where the rod-shaped body is inserted into the container for a longer time. For this purpose, it is necessary to increase the heat resistance of the material of the rod-shaped body. For example, as the rod-shaped body, a material having a melting point equal to or much higher than the temperature of the molten glass G2 is used. Such a material with a high melting point is an expensive metal such as platinum or molybdenum, so the manufacturing cost of the instrument 10 may increase. On the other hand, according to the present embodiment provided with the concave trap portion 2 capable of trapping the molten glass G2 in the lateral direction of the rod-shaped body 11, since the molten glass G2 enters the trap portion 2 and is latched, the molten glass G2 is less likely to detach from the peripheral surface of the rod-shaped body 11. Therefore, it is not necessary to spend a long time for baking the molten glass G2, and even an instrument manufactured using a material with a relatively low melting point such as stainless steel can prevent the melting damage of the instrument. For example, after the insertion operation of the rod-shaped body 11, the time until the pulling operation can be set to be 5 seconds or more and 5 minutes or less. In this way, the range of selection of the material of the rod-shaped body 11 is widened. The melting point of the material constituting the rod-shaped body 11 may be 1050 °C or more and 1800 °C or less.

[0027] In the embodiments shown in FIGS. 2 and 3, the hole 20 has a long shape in the axial direction. However, as long as the molten glass G2 can be trapped, the shape is not limited to that shown in the figures, and the axial length and the lateral length (width) may be approximately the same. Also, in the embodiments shown in FIGS. 2 and 3, the shape of the hole 20 is rectangular when viewed from the side where the hole 20 is provided. However, it may be circular, other quadrilaterals such as a rhombus, polygons other than quadrilaterals, or other shapes.

[0028] The axial length h1 of the hole 20 may preferably be 10 mm or more and 150 mm or less, more preferably 30 mm or more and 120 mm or less. When the length h1 is 10 mm or more, even when the rod-shaped body 11 is immersed in the molten glass G2, the molten glass G2 with a relatively high viscosity can enter the hole 20. Also, when the length h1 is 150 mm or less, the robustness of the rod-shaped body 11 can be ensured. Note that the length h1 is the length at the edge of the hole 20 (the length from the lower edge 21 to the upper edge).

[0029] The lateral length (width) w1 of the hole 20 is less than the outer diameter Do of the rod-shaped body 11, but may preferably be 5 mm or more and 30 mm or less, more preferably 8 mm or more and 15 mm or less. When the width w1 is 5 mm or more, even the molten glass G2 with a relatively high viscosity can enter the hole 20. Also, when the width w1 is 20 mm or less, the robustness of the rod-shaped body 11 can be ensured. Note that the width w1 is the width at the edge of the hole 20.

[0030] The axial interval s1 between the plurality of holes 20 may preferably be 5 mm or more and 30 mm or less, more preferably 10 mm or more and 20 mm or less. When the interval s1 is 5 mm or more, the robustness of the rod-shaped body can be ensured. Also, when the interval s1 is 30 mm or less, the number of holes 20 can be increased, and the positions where the molten glass G2 can be trapped can be increased, so that sampling of the molten glass G2 can be performed at a finer pitch along the axial direction.

[0031] The axial pitch p1 of the plurality of holes 20 may preferably be 15 mm or more and 180 mm or less, more preferably 40 mm or more and 140 mm or less. When the pitch p1 is 15 mm or more, the robustness of the rod-shaped body can be ensured. Also, when the interval s1 is 180 mm or less, the number of holes 20 can be increased, and the positions where the molten glass G2 can be trapped can be increased, so that sampling of the molten glass G2 can be performed at a finer pitch along the axial direction.

[0032] The number of holes 20 provided in the rod-shaped body 11 can be 2 or more and 10 or less. Also, as shown in Fig. 2(a), the positions where the plurality of holes 20 are provided may be aligned in the circumferential direction, but the circumferential positions of the plurality of holes 20 adjacent to each other in the axial direction may be offset. For example, when viewed from the side as in Fig. 3(a), one hole 20 may be formed on the left side and another hole 20 adjacent in the axial direction may be formed on the right side.

[0033] The outer diameter Do of the rod-shaped body 11 may be 10 mm or more and 50 mm or less. Thereby, firmness can be ensured and handling ease can also be improved.

[0034] Note that the rod-shaped body 11 of the evaluation instrument 10 described with reference to Figs. 2 to 4 has a configuration in which holes 20 are formed in a long cylindrical base material, but the cross-sectional shape of the base material is not limited to a circle and may be a polygon such as an ellipse or a quadrangle.

[0035] Furthermore, with reference to Figs. 5 and 6, an evaluation instrument 110 according to another embodiment will be described. The evaluation instrument 110 has a rod-shaped body 111 and a flange portion 15, similar to the evaluation instrument 10 described with reference to Figs. 2 to 4, and a plurality of trap portions 2 are provided in the axial direction on the rod-shaped body 111. However, as shown in Fig. 6, the rod-shaped body 111 is a solid body, and the trap portion 2 is a recess 120 that recesses laterally, specifically in the radial direction, from the circumferential surface of the solid rod-shaped body 111. Since the rod-shaped body 111 is solid, the overall firmness of the instrument 110 is high.

[0036] In this embodiment, like the evaluation device 10 shown in Fig. 4(b), the inside of the rod-shaped body 11 is not filled with the molten glass G2. However, as shown in Fig. 1, when the rod-shaped body 111 according to this embodiment is immersed in the molten glass G2, the molten glass G2 can also enter laterally into the recess 120. Then, the molten glass G2 adhering to the inner surface of the recess 120 is less likely to receive resistance from the glass raw material during the pulling-out operation of the evaluation device 10, so the same effect as the hole 20 of the evaluation device 10 shown in Figs. 2 to 4 can be obtained. That is, in the pulling-out operation, the part of the glass deposit that has entered the recess 120 can cause the glass deposit to be hooked on the rod-shaped body 111. Therefore, even when passing through the layer G1 of the glass raw material, it can withstand the resistance of the glass raw material and prevent the glass deposit from moving or detaching from the initial adhesion position.

[0037] The shape and dimensions of the edge of one recess 120 and the arrangement of a plurality of recesses 120 may be the same as those of the hole 20 described with reference to Figs. 2 to 4. For example, the axial length h1' of the recess 120, the width w1' of the recess 120, the axial interval s1' between a plurality of recesses 120, and the axial pitch p1' of a plurality of recesses 120 may be the same as the axial length h1 of the hole 20, the width w1 of the hole 20, the axial interval s1 between a plurality of holes 20, and the axial pitch p1 of a plurality of holes 20, respectively, and the same effect can be obtained.

[0038] Furthermore, with reference to Fig. 7, an evaluation device 210 according to still another embodiment will be described. The evaluation device 210 also includes a rod-shaped body 211 and a flange portion 15, and a trap portion 2 is formed on the rod-shaped body 211. However, the trap portion 2 in the evaluation device 210 shown in Fig. 7 is a groove 220 formed on the circumferential surface, more specifically, a spiral groove (thread groove) continuously formed on the circumferential surface of the rod-shaped body 211.

[0039] Since the thread groove 220 can be formed in a solid or hollow rod-shaped base material using, for example, a conventional thread-forming method, there is an advantage that the manufacture of the evaluation device 210 is relatively easy.

[0040] When the rod-shaped body 211 is immersed in the molten glass G2 (Fig. 1), since the molten glass G2 can also enter the thread groove 220 laterally, the same effects as those of the above-described evaluation device 10 (Figs. 2 to 4) and evaluation device 110 (Figs. 5 and 6) can be obtained. That is, in the pulling operation, the portion of the molten glass G2 that has entered the thread groove 220 can hook the glass deposits on the rod-shaped body 211. Also, when the rod-shaped body 211 passes through the layer G1 of the glass raw material, the attached molten glass G2 is not captured by the glass raw material, and the detachment of the molten glass G2 or the movement from the initially attached position can be prevented.

[0041] When compared with the hole 20 described with reference to Figs. 2 to 4 and the recess 120 described with reference to Figs. 5 and 6, since the distance that the molten glass G2 enters laterally into the thread groove 220 is small, the amount of the molten glass G2 adhering to the rod-shaped body 211 is relatively small. However, since the thread groove 220 is provided over the entire circumferential direction, the molten glass G2 can be adhered over the entire circumferential direction. Therefore, after the pulling operation of the rod-shaped body 211, the deposits of the molten glass G2 can be confirmed from anywhere on the circumferential surface. Also, when looking at the thread groove 220 along the axial direction, since a large number of grooves along the circumferential direction are arranged in the axial direction, the molten glass G2 can be continuously adhered to the surface of the rod-shaped body 211 over the entire axial direction. By observing or analyzing such continuous deposits, the continuous change in the state of the molten glass G2 along the depth direction of the melting tank 50 can be predicted. For example, the temperature distribution of the molten glass G2 in the depth direction can be estimated.

[0042] The groove width d2 at the outer edge in the radial direction of the thread groove 220 may preferably be 1 mm or more and 10 mm or less. When the groove width d2 of the thread groove 220 is 1 mm or more, the molten glass G2 having a relatively high viscosity also easily enters laterally, and the action of trapping the molten glass G2 is enhanced. Also, when the groove width d2 is 10 mm or less, the molten glass G2 is easily retained in the thread groove 220.

[0043] The depth of the thread groove 220, that is, the radial depth t2 of the thread groove 220, may preferably be 1 mm or more and 10 mm or less. By setting the depth t2 to 1 mm or more, even if the molten glass G2 has a relatively high viscosity, it is easier to enter laterally, enhancing the effect of trapping the molten glass G2. Also, by setting the depth t2 to 10 mm or less, it becomes easier to form the thread groove 220, avoiding the complication of manufacturing the evaluation device 210.

[0044] The pitch p2 of the thread groove 220 may be 1 mm or more and 10 mm or less. By setting the pitch p2 to 1 mm or more, even if the molten glass G2 has a relatively high viscosity, it is easier to enter laterally. Also, by setting the pitch p2 to 10 mm or less, the axial distance between the grooves can be reduced, increasing the friction between the rod-shaped body 11 and the molten glass G2. Thus, even when the rod-shaped body 211 passes through the layer G1 of the glass raw material during the pulling-out operation of the rod-shaped body 211, it becomes more difficult for the molten glass G2 to separate.

[0045] Incidentally, the outer diameter Do2 of the rod-shaped body 211 in the present embodiment may preferably be 8 mm or more and 30 mm or less.

[0046] FIG. 8 shows a modified example of the rod-shaped body 211 of the evaluation device 210 shown in FIG. 7. On the circumferential surface of the rod-shaped body 211 according to the example shown in FIG. 8, a groove-shaped trap portion 2 along the circumferential direction is also formed. However, in the example shown in FIG. 8, the trap portion 2 is not a thread groove 220 as shown in FIG. 7, but an annular groove 220' along the circumferential direction. As shown in FIG. 8, a plurality of annular grooves 220' formed parallel in the lateral direction are provided along the axial direction. The annular groove 220' can also be formed relatively easily using a conventional groove-forming method.

[0047] Fig. 9 shows a modified example of the evaluation instrument 10 shown in Fig. 1. In the example shown in Fig. 9, the rod-shaped main body 11 is bent in the middle to form an L shape. Therefore, the evaluation instrument 10 shown in Fig. 9 is inserted into the inside of the melting tank 50 through the side wall opening 51 formed in the side wall of the melting tank 50 and used. Then, the distal side 11a of the rod-shaped main body 11 is inserted into the melt glass G2 through the layer of the glass raw material, more specifically, through the layer G1 of the glass raw material.

[0048] In addition, one embodiment of the present disclosure is an evaluation method of the contents of a glass melting tank using the above-described instrument. The method includes inserting a rod-shaped main body into the molten glass through a layer of glass raw material, attaching the molten glass to the rod-shaped main body, then extracting it, and obtaining the thickness of the layer of glass raw material based on the position of the molten glass attached to the rod-shaped main body. Further, the above evaluation method may include sampling the molten glass and evaluating the molten glass.

[0049] As described above, the present disclosure has been described based on the embodiments, but the present disclosure is not limited to these embodiments. Also, within the scope described in the claims, various changes, modifications, substitutions, additions, deletions, combinations, etc. are possible, and these also belong to the technical scope of the present disclosure.

Explanation of Reference Numerals

[0050] 2 Trap portion 10, 110, 210 Evaluation instrument 11, 111, 211 Rod-shaped main body 15 Flange portion 20 Hole 21, 121 Lower edge 50 Glass melting tank 51 Side wall opening of the glass melting tank 53 Outlet of the glass melting tank 120 Recess 220 Thread groove 220' Annular groove G1 Layer of glass raw material (batch blanket) G2 Molten glass

Claims

1. An instrument for evaluating the contents of a glass melting tank, wherein the glass melting tank contains molten glass formed by melting glass raw materials and a layer of glass raw materials covering the upper part of the molten glass, comprises a rod-shaped body inserted into the molten glass through the layer of glass raw materials, and a trap portion for trapping the molten glass is provided on the circumferential surface of the rod-shaped body.

2. The instrument according to claim 1, wherein a plurality of the trap portions are formed at intervals along the axial direction of the rod-shaped body.

3. The instrument according to claim 2, wherein the axial length of the trap portion is 10 mm or more and 150 mm or less.

4. The instrument according to claim 2, wherein the lateral length of the trap portion perpendicular to the axial direction is 5 mm or more and 30 mm or less.

5. The rod-shaped body is a hollow body, and the trap portion is a hole penetrating the wall portion of the hollow body. The instrument according to claim 1.

6. The rod-shaped body is solid, and the trap portion is a recess recessed in the radial direction. The instrument according to claim 1.

7. The rod-shaped body is solid, and the trap portion is a groove continuous along the circumferential direction. The inspection instrument according to claim 1.

8. The instrument according to claim 7, wherein the groove is a spiral groove.

9. The instrument according to claim 8, wherein the width of the groove is 1 mm or more and 10 mm or less.

10. The instrument according to claim 1, wherein the viscosity of the molten glass is 10^1.5 dPa·s or more and 10^4 dPa·s or less.

11. The instrument according to claim 1, wherein the rod-shaped body is formed of a material having a melting point of 1050 °C or more and 1800 °C or less.

12. A positioning mark is provided on the rod-shaped body closer to the proximal side than the plurality of trap portions, and the instrument is used to measure the thickness of the layer of glass raw materials. The instrument according to claim 1.

13. An evaluation method for the contents of a glass melting tank using the instrument according to any one of claims 1 to 11, wherein the rod-shaped body is inserted into the molten glass through the layer of glass raw materials, and after the molten glass is adhered to the rod-shaped body, it is withdrawn, and the thickness of the layer of glass raw materials is determined based on the position of the molten glass adhered to the rod-shaped body.

14. The evaluation method according to claim 13, further comprising sampling the molten glass and evaluating the molten glass.

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