Heating furnace

Abstract

To provide a furnace having a novel structure capable of retarding heat degradation of a sealing member disposed around an opening.SOLUTION: A roller hearth-type furnace 1 includes: an opening 9 formed in a furnace body 5; a seal member 16 provided in a peripheral part of the opening 9 and surrounding the opening 9; and a furnace door 25 that moves up and down in a vertical direction and opens / closes the opening 9. The furnace door 25 includes a frame member 27 having a first face 27a that contacts the seal member 16 when the opening 9 is closed and a second face 27b extending in a direction intersecting the first face 27a inside the first face 27a. At least part of a heat insulating material that covers the second face 27b is configured of a blanket-like heat insulating material 30b having flexibility, and the blanket-like heat insulating material 30b is arranged flush with respect to the first face 27a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a heating furnace, and more particularly to a heating furnace characterized by technical means for suppressing thermal degradation of a seal member disposed around an opening.

Background Art

[0002] In a heating furnace used in the steel industry, a furnace door for preventing heat radiation may be provided at an opening formed in the furnace body for loading and / or unloading an object to be heat-treated. In this case, a seal member that comes into contact with the furnace door to maintain the airtightness inside the furnace is used around the opening, but the seal member has a problem of being easily deteriorated by the heat inside the furnace.

[0003] As a method for protecting such a seal member from heat, there is a method of directly or indirectly cooling the seal member using cooling water (refrigerant) (see, for example, Patent Document 1 below). However, the method of cooling the seal member using cooling water has many problems such as a decrease in the furnace temperature due to leakage of the cooling water piping, occurrence of failures in equipment around the piping, a decrease in the amount of water due to clogging of the cooling water piping and the accompanying furnace shutdown, and freezing of the cooling water in cold regions. In addition, the cooling water also causes a decrease in the thermal efficiency inside the furnace.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention is based on the above circumstances, and an object thereof is to provide a heating furnace having a novel structure capable of suppressing thermal degradation of a seal member disposed around an opening.

Means for Solving the Problems

[0006] The heating furnace according to the first aspect of the present invention is defined as follows. That is, an opening formed in the furnace body for loading and / or unloading the object to be heat-treated, a seal member provided at the peripheral edge of the opening and surrounding the opening, a furnace door that moves up and down in the vertical direction to open and close the opening, A heating furnace comprising: The furnace door includes a frame member having a first surface that contacts the seal member when the opening is closed, and a second surface that extends in a direction intersecting the first surface inside the first surface. At the same time, At least a part of the heat insulating material covering the second surface is composed of a flexible blanket-shaped heat insulating material, and the blanket-shaped heat insulating material is provided flush with the first surface.

[0007] According to the heating furnace of the first aspect defined in this way, since the second surface side of the frame member in contact with the seal member is covered with the heat insulating material, the temperature rise of the seal member due to the heat in the furnace being transmitted to the seal member through the frame member of the furnace door is suppressed, and the heat deterioration of the seal member disposed around the opening can be suppressed. Here, when the heat insulating material on the furnace door side is provided flush with the first surface, the gap between the opposing furnace body side furnace shell member and the furnace door side heat insulating material becomes small. Therefore, in the heating furnace of the first aspect, a flexible blanket-shaped heat insulating material is provided at a position flush with the first surface so that the heat insulating material is less likely to be damaged even when the heat insulating material on the furnace door side contacts the furnace shell member on the furnace body side when the furnace door moves up and down.

[0008] The second aspect of the present invention is defined as follows. That is, In the heating furnace defined in the first aspect, on the back side of the blanket-shaped heat insulating material provided on the furnace door, which is opposite to the opening side, a low thermal conductivity heat insulating material having a thermal conductivity of 0.045 [W / m / K] or less at 600 °C is provided so as to cover the second surface. According to the heating furnace of the second aspect defined in this way, due to the effect of the low thermal conductivity heat insulating material, the temperature rise of the seal member can be further suppressed.

[0009] The third aspect of the present invention is defined as follows. That is, In the heating furnace defined in the second aspect, a lower seal member provided below the opening and a lower frame member of the furnace door that contacts the lower seal member are arranged between two adjacent rollers for conveying the workpiece to be heat-treated. When the low thermal conductivity heat insulating material is used as described above, the heat insulating effect is high and the furnace door can be configured compactly. Therefore, the layout in which the lower seal member and the lower frame member of the furnace door are arranged between two adjacent rollers for conveying the workpiece to be heat-treated can be easily realized.

[0010] The fourth aspect of the present invention is defined as follows. That is, In the heating furnace defined in any one of the first to third aspects, the opening closing surface of the furnace door has a recessed shape in which a central region where the blanket-shaped heat insulating material is not disposed is recessed. According to the heating furnace of the fourth aspect defined as above, a gap can be ensured between the central region of the furnace door, where the effect of suppressing the temperature rise of the seal member is relatively small, and the furnace shell member on the furnace body side, and contact between the furnace shell member on the furnace body side and the central region can be avoided.

[0011] The fifth aspect of the present invention is defined as follows. That is, In the heating furnace defined in any one of the first to fourth aspects, the blanket-shaped heat insulating material is connected to the iron sheet via studs, and The blanket-shaped heat insulating material is formed with a recess, and the tip-side end of the stud is accommodated in the recess. According to the heating furnace of the fifth aspect defined as above, contact between the tip-side end of the stud and the furnace shell member on the furnace body side can be avoided.

[0012] The sixth aspect of the present invention is defined as follows. That is, In the heating furnace defined in any one of the first to fifth aspects, the heat insulating material on the furnace body side located between the seal member and the opening is protruded toward the furnace door side from the seal member mounting surface to which the seal member is attached, and the heat insulating material on the furnace body side is brought into contact with the furnace door in the furnace door closed state. According to the heating furnace of the sixth aspect defined in this way, since the gap of the heat insulating material that shields between the opening and the seal member in the state where the furnace door is closed can be eliminated (or made extremely small), the temperature rise of the seal member can be further suppressed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

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Figure 5

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Figure 8

Figure 9

Mode for Carrying Out the Invention

[0014] Next, embodiments of the present invention will be described in detail below.

[0015] Figure 1 shows a schematic configuration of a roller hearth type heating furnace according to an embodiment of the present invention. In the figure, 1 is a roller hearth type heating furnace (hereinafter sometimes simply referred to as a heating furnace), which heat-treats an object to be heat-treated such as steel or ceramics while placed on a tray. In the following, as shown in Figure 1, the vertically upward direction is defined as the upward direction, the vertically downward direction is defined as the downward direction, the downstream side in the direction of loading (charging) the object to be heat-treated W into the heating furnace 1 is defined as the forward direction, and the upstream side in the direction of loading the object to be heat-treated W into the heating furnace 1 is defined as the backward direction for explanation.

[0016] As shown in Figure 1, the heating furnace 1 includes a steel furnace body 5. The furnace body 5 has a heat-resistant insulating material 6 inside, and the insulating material 6 constitutes an insulating wall 7. The inside of the insulating wall 7 is a heating chamber 10 for accommodating the object to be heat-treated W, and a burner 12 and a stirring fan 14 as heating means are provided in the heating chamber 10. An opening 9 for loading and unloading the object to be heat-treated W is formed on the right side of the furnace body 5 in the figure, and heat treatment is performed on the object to be heat-treated W accommodated in the heating chamber 10 through the opening 9.

[0017] A plurality of conveying rollers 20 are arranged in parallel along the front-rear direction, which is the conveying direction, in the interior of the heating chamber 10 and in the area outside the furnace near the opening 9. In the figure, 21 is a drive motor for rotating the roller 20. By rotating the drive motor 21 forward, the object to be heat-treated W is loaded into the furnace, and by rotating the drive motor 21 backward, the object to be heat-treated W is unloaded out of the furnace.

[0018] The opening 9 is provided with a furnace door 25 that moves up and down in the vertical direction by an opening / closing device 24 to open and close the opening 9. In Figure 1, the closed furnace door 25 is shown by a solid line, and the open furnace door 25 is shown by a two-dot chain line.

[0019] 17 is a pressing device provided close to the furnace door 25. Based on the driving force from a motor or the like (not shown), the link 17b swings around the rotation axis 17a, and the closed furnace door 25 is pressed toward the opening 9.

[0020] FIG. 2 is a perspective view showing the periphery of the opening of the furnace body 5 and the furnace door 25 separated from each other. FIG. 3 is a cross-sectional view showing the periphery of the opening of the furnace body 5 and the furnace door 25 separated from each other. As shown in FIG. 2, a seal member 16 that comes into contact with the furnace door 25 to maintain the airtightness inside the furnace is mounted so as to surround the opening 9 at the peripheral edge of the opening 9 formed in the furnace body 5. Specifically, as shown in FIG. 3, the seal member 16 is mounted on the seal member mounting surface 41a of the metal furnace shell member 41 disposed around the opening 9. In this example, a rope-shaped seal member made of heat-resistant ceramic fiber and a rubber binder is used as the seal member 16. The heat-resistant temperature of such a seal member 16 is approximately 500°C.

[0021] Next, the configuration of the furnace door 25 that closes the opening 9 will be described. The furnace door 25 includes a frame member 27, an iron sheet 28, and a heat insulating material portion 30, and as a whole, it has a substantially rectangular plate shape as shown in FIG. 2. When the furnace door 25 is viewed from the side, the iron sheet 28 in the vicinity of the lower side (lower frame member 34) of the frame member 27 is tapered so as not to interfere with the roller 20 located on the rear side (see FIGS. 1 and 5).

[0022] The frame member 27 is a rectangular frame-shaped annular body using a square tubular metal pipe, and is integrally joined to the peripheral edge of the iron sheet 28. The frame member 27 includes a first surface 27a that faces the seal member 16 on the furnace body side and comes into contact with the seal member 16, and a second surface 27b that is orthogonal to the first surface 27a on the inner side of the first surface 27a (the side facing the center of the furnace door 25), as shown in FIG. 3.

[0023] As shown in FIG. 3, the heat insulating material portion 30 is formed by laminating a plurality of heat insulating materials 30a, 30b, 30c, 30d in a housing space 29 defined by the frame member 27 and the iron sheet 28 and opened to the opening 9 side of the furnace body 5, and closes the opening 9 of the furnace body 5 in the furnace door closed state. The material of these heat insulating materials is not particularly limited, but refractory materials with a high porosity, ceramic fibers, ceramic particles formed into a board shape or a flexible blanket shape, etc. can be used.

[0024] As shown in Fig. 3, the heat insulating material portion 30 is disposed so as to cover the second surface 27b of the frame member 27 in the peripheral region 31 close to the frame member 27. Specifically, the heat insulating material is disposed up to the same height as the first surface 27a so as to cover the corner where the first surface 27a and the second surface 27b of the frame member 27 intersect. This is because if the second surface 27b of the frame member 27 is exposed, the frame member 27 is heated through such an exposed portion, and the temperature of the seal member 16 in contact with the frame member 27 becomes high.

[0025] In this example, as the heat insulating material that covers the second surface 27b of the frame member 27, a low thermal conductivity heat insulating material 30a having a thermal conductivity of 0.045 [W / m / K] or less at 600°C is used. By doing so, it is possible to favorably suppress the transmission of the temperature of the heating chamber 10 to the frame member 27. Note that the thermal conductivities of the heat insulating materials 30b, 30c, and 30d other than the low thermal conductivity heat insulating material 30a used in this example are 0.15 to 0.25 [W / m / K] at 600°C. As the low thermal conductivity heat insulating material 30a, for example, a heat insulating material having a microporous structure in which ceramic particles of micron order or less are used to reduce the void size between particles can be used. The low thermal conductivity heat insulating material having a microporous structure is more brittle than other heat insulating materials and has a problem of being easily cracked. Therefore, in this example, the surface of the low thermal conductivity heat insulating material 30a is covered with a blanket-shaped heat insulating material 30b to prevent damage to the low thermal conductivity heat insulating material 30a.

[0026] On the other hand, in the region inside (closer to the center) than the low thermal conductivity heat insulating material 30a, a blanket-shaped heat insulating material 30d is laminated, and a board-shaped heat insulating material 30c is laminated on the surface thereof. The board-shaped heat insulating material 30c is laminated so as to be flush with the low thermal conductivity heat insulating material 30a. And the peripheral portion of the board-shaped heat insulating material 30c is further covered with a blanket-shaped heat insulating material 30b. As a result, the opening / closing surface 26 of the furnace door 25 has a recessed shape in which the central region 32 where the blanket-shaped heat insulating material 30b is not disposed is recessed with respect to the peripheral region 31 where the blanket-shaped heat insulating material 30b is disposed.

[0027] As shown in Fig. 3, these laminated heat insulators 30a, 30b, 30c, 30d are connected via studs 35 with one end joined to the iron sheet 28. Specifically, a flange-like member 36 is screwed to the tip-side end portion 35b of the stud 35 extending toward the furnace body 5 side, and the heat insulator is sandwiched between the iron sheet 28 and the flange-like member 36. In this example, a recess 37 is formed in the blanket-like heat insulator 30b, and the tip-side end portion 35b of the stud 35 is accommodated in the recess 37. This is to prevent the tip-side end portion 35b of the stud 35 from interfering with the furnace shell member when the furnace door is lifted or lowered.

[0028] As described above, the structure of the furnace door 25 has been explained by taking the upper and lower parts of the furnace door 25 shown in Fig. 3 as examples. The left and right parts of the furnace door 25 shown in Fig. 4(C) also have the same features.

[0029] Next, the heat insulator disposed near the opening 9 on the furnace body 5 side will be described. As shown in Fig. 3, on the furnace body 5 side, a heat insulator is provided so as to block between the furnace shell member 41 to which the seal member 16 is attached and the heating chamber 10, and between the furnace shell member 41 and the opening 9. And a part of the heat insulator is made of a low thermal conductivity heat insulator 42a having a thermal conductivity of 0.045 [W / m / K] or less at 600 °C, similar to the case of the furnace door 25. In the furnace shell member above the opening 9, the low thermal conductivity heat insulator 42a is formed in a plate shape in a cross-sectional view extending in the horizontal direction (front-rear direction) between the opening 9 and the furnace shell member 41. On the other hand, in the furnace shell member below the opening 9, the low thermal conductivity heat insulator 42a extends in the vertical direction between the furnace shell member 41 and the heating chamber 10 and is formed in a substantially T shape in a cross-sectional view extending in the horizontal direction (front-rear direction) between the opening 9 and the furnace shell member 41. In this example, considering the difference in the thickness of the heat insulator 42c, the cross-sectional view shape of the low thermal conductivity heat insulating member 42a is made different between the upper side and the lower side of the opening 9. However, for example, as shown in the partial enlarged view of Fig. 3, the cross-sectional view shape of the upper low thermal conductivity heat insulating member 42a can also be made substantially T-shaped in a cross-sectional view, similar to the lower side. Also, in some cases, both can be made plate-shaped in a cross-sectional view. The low thermal conductivity heat insulating material 42a is laminated together with other blanket-shaped heat insulating materials 42b, 42c, etc., and one end is connected to an iron sheet (not shown) via the stud 35.

[0030] Figs. 5 and 6 are explanatory views of the opening and closing operations of the furnace door 25 in the heating furnace 1. As shown in Fig. 5, in the heating furnace 1 of this example, the lower seal member 19 provided below the opening 9 is provided between two adjacent conveying rollers 20, 20. When the workpiece W to be heat-treated is carried in and out, the furnace door 25 that has once risen to the position indicated by the two-dot chain line in Fig. 5 descends downward to a predetermined position where the opening closing surface 26 of the furnace door 25 faces the opening 9 after the workpiece W to be heat-treated has passed through the opening 9. At this time, the lower frame member 34 of the furnace door 25 that contacts the lower seal member 19 will be located between the two adjacent conveying rollers 20, 20.

[0031] Thereafter, due to the pressing action of the link 17b of the pressing device 17 (see Fig. 1), as shown in Fig. 6, the furnace door 25 is pressed against the opening 9 side, and the first surface 27a of the frame member 27 of the furnace door 25 contacts the seal member 16 to ensure the airtightness inside the furnace. At this time, since the heating chamber 10, the opening 9, and the seal member 16 are shielded by the heat insulating material except for the gap δ portion, the high temperature of the seal member 16 due to the heat from the furnace interior is suppressed.

[0032] Next, the results of an investigation on the temperature distribution of the seal member in the heating furnace 1 and the workpiece W being heat-treated in the heating chamber will be described. Regarding the investigation of the seal member temperature, the inside of the heating chamber 10 in an N2 atmosphere was heated in the heat pattern shown in Fig. 7(A) to confirm how high the temperature of the seal member 16 would rise. The temperature measurement points P are eight points indicated by black circles in Fig. 7(B), and the temperature measurement was performed using a sheathed thermocouple. As a result of the investigation, the maximum temperature at each measurement point was 149°C to 234°C, which was sufficiently lower than the heat-resistant temperature of 500°C of the seal member 16.

[0033] Regarding the temperature distribution of the object to be heat-treated W, as shown in Fig. 8, a total of 10 objects to be heat-treated (wire coils) W stacked in two layers were loaded into the heating chamber 10. The heating chamber in an N2 atmosphere was heated in the heat pattern shown in Fig. 7(A), and the temperature distribution of the object to be heat-treated W at the end of soaking held at 900°C was confirmed. The temperature measurement points P are 12 points indicated by black circles in Fig. 8, and the temperature measurement was performed using a sheathed thermocouple. As a result of the investigation, the width of the temperature variation at the 12 measurement points was 6.6°C. Note that when a water-cooling method was adopted in which water was circulated inside the frame member 27 on the furnace door 25 side in contact with the seal member 16 to cool the seal member 16 under the same conditions, the width of the temperature variation at the 12 measurement points was 8.1 to 9.2°C. Therefore, it can be seen that the configuration of this embodiment that suppresses the temperature of the seal member 16 without performing water-cooling is also excellent in terms of temperature uniformity.

[0034] As described above, according to the heating furnace 1 of this embodiment, since the second surface 27b side of the frame member 27 in contact with the seal member 16 is covered with a heat insulating material, the increase in temperature of the seal member 16 due to the heat in the furnace being transmitted to the seal member 16 through the frame member 27 of the furnace door 25 is suppressed, and the thermal deterioration of the seal member 16 disposed around the opening 9 can be suppressed. Here, in this embodiment, since the heat insulating material on the furnace door 25 side is provided flush with the first surface 27a, the gap with the furnace shell member on the opposing furnace body side becomes small. Therefore, in this embodiment, a blanket-shaped heat insulating material 30b having flexibility is provided at a position flush with the first surface 27a so that the heat insulating material is less likely to be damaged even when the furnace door 25 comes into contact with the furnace shell member on the furnace body side when the furnace door is lifted and lowered.

[0035] According to the heating furnace of this embodiment, a low thermal conductivity heat insulating material 30a having a thermal conductivity of 0.045 [W / m / K] or less at 600°C is provided so as to cover the second surface 27b on the back side of the blanket-shaped heat insulating material 30b provided on the furnace door 25, on the side opposite to the opening 9 side. With such a low thermal conductivity heat insulating material 30a, the increase in temperature of the seal member 16 can be further suppressed.

[0036] When the low thermal conductivity heat insulating material 30a is used, the heat insulating effect is high and the furnace door 25 can be configured compactly. Therefore, a layout in which the lower sealing member 19 and the lower frame member 34 of the furnace door 25 are arranged between two adjacent conveying rollers 20, 20 can be easily realized.

[0037] According to the heating furnace of the present embodiment, as shown in FIG. 3, in the opening / closing surface 26 of the furnace door 25, a central region 32 where a blanket-like heat insulating material 30b is not disposed is recessed to form a recessed shape. For this reason, with respect to the central region 32 where the effect of suppressing the temperature rise of the sealing member 16 is relatively small, a gap with the furnace shell member on the furnace body 5 side can be secured, and contact between the furnace shell member on the furnace body side and the central region 32 can be avoided.

[0038] FIG. 9 shows a modification of the above embodiment. In this example, as shown in FIG. 9(A), the heat insulating materials 42a and 42b on the furnace body 5 side located between the sealing member 16 and the opening 9 are protruded to the furnace door 25 side from the sealing member mounting surface 41a to which the sealing member 16 is attached. In the furnace door closed state shown in FIG. 9(B), the end faces 50 of the heat insulating materials 42a and 42b can be brought into contact with the furnace door 25. By doing so, since the gap δ (see FIG. 6) between the end of the opening 9 and the furnace door 25 that existed in the above embodiment can be eliminated, the temperature rise of the sealing member 16 can be further suppressed.

[0039] Although the embodiments of the present invention have been described in detail above, this is merely an example. For example, as the frame member of the furnace door in contact with the sealing member, it is also possible to use a solid square bar, a plate material bent into an L shape, etc. instead of a square tube-shaped member. Further, the above embodiment is an example in which one opening is provided in the furnace body, but the present invention can also be applied to a continuous heating furnace provided with two openings, an inlet opening and an outlet opening. The present invention can be configured in various modified forms without departing from the spirit thereof.

Explanation of Reference Numerals

[0040] 1 Roller hearth type heating furnace 5 Furnace body 9 Opening 16 Sealing member 20 Roller for conveying heat-treated object 25 Furnace door 27a First surface 27b Second surface 28 Sheet metal 30 Heat insulation material part 30a Heat insulation material with low thermal conductivity 30b Blanket-shaped heat insulation material 31 Peripheral region 32 Central region 35 Stud 35b Tip-side end part 37 Recess 41a Sealing member mounting surface 42a Heat insulation material with low thermal conductivity W Heat-treated object

Claims

1. An opening formed in a furnace body for loading and / or unloading a workpiece to be heat-treated, a seal member provided at a peripheral edge of the opening to surround the opening, a furnace door that moves up and down in a vertical direction to open and close the opening, a heating furnace comprising: the furnace door includes a frame member having a first surface that contacts the seal member when the opening is closed, and a second surface that extends in a direction intersecting the first surface inside the first surface, at least a part of the heat insulating material covering the second surface is composed of a flexible blanket-shaped heat insulating material, and the blanket-shaped heat insulating material is provided flush with the first surface. A heating furnace.

2. On the back side of the blanket-shaped heat insulating material provided on the furnace door, which is opposite to the opening side, a low thermal conductivity heat insulating material having a thermal conductivity of 0.045 [W / m / K] or less at 600°C is provided so as to cover the second surface. The heating furnace according to claim 1.

3. The lower seal member provided below the opening and the lower frame member of the furnace door that contacts the lower seal member are arranged between two adjacent rollers for conveying the workpiece to be heat-treated. The heating furnace according to claim 2.

4. The opening closing surface of the furnace door has a recessed shape in which a central region where the blanket-shaped heat insulating material is not disposed is recessed. The heating furnace according to any one of claims 1 to 3.

5. The blanket-shaped heat insulating material is connected to an iron sheet via studs, a recess is formed in the blanket-shaped heat insulating material, and the tip-side end of the stud is accommodated in the recess. The heating furnace according to any one of claims 1 to 4.

6. The heat insulating material on the furnace body side located between the seal member and the opening is protruded toward the furnace door side from the seal member mounting surface to which the seal member is attached, and the heat insulating material on the furnace body side is brought into contact with the furnace door in a closed state of the furnace door. The heating furnace according to any one of claims 1 to 5.

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