JP7382800B2 - Far-infrared multistage heating furnace for hot pressing steel plates - Google Patents

Description

The present invention relates to a far-infrared multi-stage heating furnace for hot-pressing steel sheets, and specifically, a far-infrared multi-stage heating furnace for heating hot-pressing steel sheets to a predetermined temperature range (for example, Ac3 point or higher and 950°C or lower). Regarding type heating furnaces.

BACKGROUND ART In recent years, a hot pressing method (also referred to as a hot stamping method) has been used as a press forming method for structural members of automobile bodies. In the hot press method, the hot press steel plate (blank) used for press forming is heated to a temperature of Ac3 or higher, then immediately formed using a press mold, rapidly cooled, and quenched (also called die quench). . As a result, a high-strength press-formed product having a desired shape is manufactured.

In order to mass-produce high-strength hot press-formed products by the hot press method, it is necessary to use a heating furnace for heating the steel plate for hot press. Inventions related to such heating furnaces have been proposed so far.

A multi-stage heating furnace is disclosed in Patent Document 1. This multistage heating furnace includes a plurality of accommodation spaces for accommodating a plurality of hot press steel plates.

It is possible to uniformly and rapidly heat a steel plate for hot pressing to a high temperature range of Ac 3 or higher (e.g. 850 to 950℃) regardless of its location, improve mass productivity, and minimize the installation area. , required for heating furnaces. The heating furnace described in Patent Document 1 is equipped with a thin, flat, far-infrared heater as a heating source for a steel plate for hot pressing. This heating furnace combines the features a to c listed below.
(a) A steel plate for hot pressing can be heated uniformly.
(b) Compactness can be achieved by multistage in the vertical direction.
(c) It is thin and can heat a hot press steel plate from both sides.

The far-infrared heater described in Patent Document 1 has a woven structure in which a large number of insulators are lined up vertically and horizontally to form a flexible panel. Many insulators have grooves that accommodate heating conductors, which are resistors. Heat-generating conductors that emit far-infrared rays are inserted and provided inside these grooves.

Patent No. 5990338 specification

In a far-infrared heating furnace for hot-pressing steel plates, we have made the furnace installation area more compact by increasing the number of stages, and we have also minimized the pitch between vertical heating units by using a thin flexible heater that can heat both sides. There is a need to maximize the number of stages at a given overall height. Therefore, means for supporting the far-infrared heater is required so that the flexible far-infrared heater maintains its horizontal shape within the furnace without being bent.

Since this supporting material is exposed to high temperatures by a far-infrared heater, it is required to have the following properties.
(1) Must have the specified bending strength in a high temperature atmosphere of 850℃ to 950℃.
(2) The high-temperature creep strain rate is sufficiently low in a high-temperature atmosphere of 850°C to 950°C.
(3) It is possible to freely expand and contract thermally, and the thermal stress that the support material receives is sufficiently small.
(4) To withstand thermal shock during the temperature raising/lowering process from room temperature to 950°C.
(5) The far-infrared heater can be supported with as small a planar projected area as possible.

In the configuration described in Patent Document 1, in order to support one far-infrared heater, a plurality of heater supports made of metal plates made of a heat-resistant alloy are lined up to support the far-infrared heater from below. The metal plate heater support material suffers from high-temperature creep strain in the above-mentioned high-temperature atmosphere, so it may warp during long-term operation and may not be able to maintain the far-infrared flexible heater in a horizontal plane.

In view of the above-mentioned circumstances, the present invention provides a far-infrared multi-stage heating furnace for hot-pressing steel sheets, which prevents the member supporting the far-infrared heater from bending even when the heating furnace is operated for a long period of time. The aim is to ensure that it can be suppressed.

The gist of the present invention is a far-infrared multistage heating furnace for hot pressing steel plates as described below.

(1) A block including a heat insulating material placed surrounding the horizontal surface of a space that accommodates a hot press steel plate, and a block above a portion of the space where the hot press steel plate is placed and heated; A far-infrared multi-stage heating furnace including a heating unit having a far-infrared heater disposed below to heat the hot pressing steel plate,
comprising a plurality of heater support beams supporting the far-infrared heater,
Each of the heater support beams includes a ceramic member;
A steel plate for hot pressing, further comprising an end support member that supports an end of each of the heater support beams so that each of the heater support beams can freely expand and contract in the longitudinal direction due to heat. Far-infrared multi-stage heating furnace.

(2) The far-infrared multi-stage heating furnace for hot pressing steel sheets according to (1) above, wherein the end support material supports the ceramic member directly or indirectly through an intermediate body. .

(3) Far-infrared multistage heating of a steel plate for hot pressing according to (2) above, wherein the intermediate body includes a metal member provided at the end of the heater support beam and attached to the ceramic member. Furnace.

(4) The far-infrared multistage heating furnace for hot pressing steel plates according to (3), wherein the metal member is a metal plate and is inserted into the ceramic member.

(5) The bending strength of the ceramic member is higher than the bending strength of the metal member at the temperature of the space when the far-infrared heater is heating the hot pressing steel plate; The far-infrared multistage heating furnace for hot pressing steel sheets according to (4) above.

(6) Far-infrared multistage heating of a steel plate for hot pressing according to any one of (3) to (5) above, wherein the metal member and the ceramic member are connected via a pin. Furnace.

(7) At least one of the metal member and the ceramic member has a pin hole into which the pin is inserted so as to be movable relative to the pin in the longitudinal direction, and the pin and the pin hole in the longitudinal direction The gap at normal temperature is equal to or larger than the amount of relative displacement between the pin and the pin hole when the space changes from room temperature to the temperature when the hot pressing steel plate is heated by the far-infrared heater. ) A far-infrared multistage heating furnace for hot pressing steel sheets.

(8) The end support material directly supports the ceramic member,
The far-infrared multistage heating furnace for hot pressing steel sheets according to (2) above, wherein the end portion of the ceramic member is closed with a lid containing a heat insulating material.

(9) The end support material directly supports the ceramic member,
The end support member has a through hole portion through which the ceramic member passes and receives the ceramic member;
The far-infrared multi-stage type of hot pressing steel plate according to (2) or (8), wherein the size of the through hole portion is larger than the size of the ceramic member in a cross section perpendicular to the longitudinal direction. heating furnace.

(10) The far-infrared multi-stage heating furnace for hot pressing steel sheets according to any one of (1) to (9), wherein the end support material is disposed outside the block.

(11) The far-infrared heater has a plurality of insulator bodies, which are sintered bodies of far-infrared radiation emitting ceramics, lined up in a planar manner vertically and horizontally. The steel plate for hot pressing according to any one of (1) to (10), which has flexibility by being movably connected to each other by heating wires inserted into heated wire through holes. Far-infrared multi-stage heating furnace.

(12) The far-infrared multistage heating furnace for hot pressing steel sheets according to any one of (1) to (11), wherein the ceramic member is made of silicon carbide ceramics.

(13) The far-infrared multistage heating furnace for hot pressing steel sheets according to any one of (1) to (12), wherein the ceramic member has a square tube shape.

(14) the plurality of heater support beams are arranged parallel to each other while being separated from each other in one direction;
further comprising a plurality of second heater support beams that are arranged in line in another direction intersecting the one direction and support the far-infrared heater,
Each of the second heater support beams is supported by the plurality of heater support beams such that each of the second heater support beams can freely expand and contract in the longitudinal direction of the second heater support beams due to heat. The far-infrared multistage heating furnace for hot pressing steel sheets according to any one of (1) to (13) above.

According to the present invention, even when the heating furnace is operated for a long period of time, it is possible to more reliably suppress the bending of the member supporting the far-infrared heater.

FIG. 1(a) is a plan view of an insulator body used in a flexible far-infrared heater, FIG. 1(b) is a front sectional view of the insulator body, and FIG. 1(c) is a plan view of the flexible far-infrared heater. 1(d) is a front view showing a state in which heating wires are passed through the arrayed insulators and woven into a bamboo blind shape, and FIG. 1(e) is a side view of FIG. 1(c). 1(f) is a diagram showing a state in which the insulator bodies are arranged one-half apart from each other. FIG. 2 is an overall view of the far-infrared multistage heating furnace according to the present invention, and is an explanatory view showing the exterior panel and the furnace body frame. FIG. 3 is an explanatory diagram of a far-infrared multistage heating furnace according to the present invention, FIG. 3(a) is an explanatory diagram showing the appearance of the far-infrared multistage heating furnace, and FIG. , FIG. 3(c) is an explanatory diagram showing the heating unit, FIG. 3(c) is an AA sectional view in FIG. 3(b), and FIG. 3(d) is an explanatory diagram showing the heating unit with the lid block removed. FIG. 3(e) is a BB cross-sectional view in FIG. 3(b). FIG. 4 is an explanatory diagram of a far-infrared multistage heating furnace, showing some heating units. FIG. 5 is a front view of a far-infrared multistage heating furnace. FIG. 6(a) is an explanatory diagram showing the heater support member of the far-infrared heater in the heating unit, FIG. 6(b) is a top view of the heating unit, and FIG. 6(c) is an explanatory diagram showing the far-infrared heater and the heater support member in the heating unit. FIG. 6D is an explanatory diagram showing the arrangement of hot press steel plates, and FIG. 6D is an explanatory diagram showing another support unit for the far-infrared heater in the heating unit. FIG. 7A is a longitudinal sectional view showing a state in which the first heater support beam is cut along the longitudinal direction of the first heater support beam. FIG. 7(b) is a sectional view taken along line CC in FIG. 7(a). FIG. 8A is a plan view of a first heater support beam according to a modification. FIG. 8(b) is a side view of the first heater support beam. FIG. 9(a) is an enlarged view of one end of the first heater support beam shown in FIG. 8(a). FIG. 9(b) is a cross-sectional view taken along line DD in FIG. 9(a). FIG. 10(a) is a diagram for explaining a modification of the pin hole. FIG. 10(b) is a diagram for explaining a modification of the pin arrangement.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

1. Structure of Furnace Frame 12 FIG. 2 is an overall view of the far-infrared multistage heating furnace 10 according to the present invention, and is an explanatory diagram showing the exterior panels 11a, 11b, 11c and the furnace frame 12.

FIG. 3 is an explanatory diagram of a far-infrared multi-stage heating furnace 10 according to the present invention, FIG. 3(a) is an explanatory diagram showing the appearance of the far-infrared multi-stage heating furnace 10, and FIG. ) is an explanatory diagram showing the heating units 13-1 to 13-6, FIG. 3(c) is an AA sectional view in FIG. 3(b), and FIG. 3(d) is an explanatory diagram showing the heating units 13-1 to 13-6. , 16d are explanatory views showing the heating units 13-1 to 13-6 with the heating units 13-1 to 13-6 removed, and FIG. 3(e) is a sectional view taken along line BB in FIG. 3(b).

FIG. 4 is an explanatory diagram of the far-infrared multi-stage heating furnace 10, showing only the heating units 13-1 and 13-2 among the heating units 13-1 to 13-6. FIG. 5 is a front view of the far-infrared multistage heating furnace 10.

As shown in FIGS. 2 to 5, the far-infrared multistage heating furnace 10 includes heating units 13-1 to 13-6, a ceiling unit 19, and a furnace frame 12.

The heating units 13-1 to 13-6 each have a space for accommodating the hot pressing steel plates 15-1 to 15-6. This space is formed by blocks 16a, 16b, 16c, 16d, 16e, and 16f made of heat insulating material and arranged to surround the space. Each of the heating units 13-1 to 13-6 accommodates substantially horizontally supported hot pressing steel plates 15-1 to 15-6 inside this space.

A plurality of heating units 13-1 to 13-6 (six in the far-infrared multistage heating furnace 10 shown in FIGS. 2 to 5) are provided in a vertically stacked manner.

The heating units 13-1 to 13-6 have far-infrared heaters 14-1 to 14-6, and the ceiling unit 19 has a far-infrared heater 14-7. The far-infrared heaters 14-1 to 14-7 are arranged above and below the hot press steel plates 15-1 to 15-6 housed in the space. That is, the far infrared heaters 14-1 and 14-2 are respectively arranged above and below the hot press steel plate 15-1, and the far infrared heaters 14-2 and 14-3 are respectively arranged above and below the hot press steel plate 15-1. The far infrared heaters 14-3 and 14-4 are arranged above and below the hot press steel plate 15-3, respectively, and the far infrared heaters 14-4 and 14-5 are arranged above and below the hot press steel plate 15-3, respectively. The far infrared heaters 14-5 and 14-6 are arranged above and below the hot press steel plate 15-4, respectively, and the far infrared heater 14-6 , 14-7 are arranged above and below the hot press steel plate 15-6, respectively.

In this way, the far-infrared heaters 14-1 to 14-7 heat the hot press steel plates 15-1 to 15-6 from above and below, respectively, to, for example, above the Ac3 transformation point and below 950°C. That is, the far-infrared heaters 14-1 to 14-7 heat the hot-pressing steel plates 15-1 to 15-6 in the space where the hot-pressing steel plates 15-1 to 15-6 are arranged. The hot press steel plates 15-1 to 15-6 are heated.

The far-infrared heaters 14-1 to 14-7 are flexible planar infrared heaters (hereinafter sometimes referred to as "flexible far-infrared heaters") disclosed in Registered Utility Model No. 3056522.

The far-infrared heaters 14-1 to 14-7 each have an insulator body 1, as shown in FIGS. 1(a) to 1(f). The insulator body 1 is a sintered body of far-infrared emitting ceramics such as Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ , SiC, CoO, Si ₃ N ₄ or the like. The far-infrared heaters 14-1 to 14-7 have a planar configuration in which a plurality of insulator bodies 1 are lined up vertically and horizontally. The plurality of insulator bodies 1 are movably connected to each other by heating wires 4 inserted into heating wire through holes 2 formed in each of the plurality of insulator bodies 1. The far-infrared heaters 14-1 to 14-7 are flexible far-infrared heaters.

The far-infrared heaters 14-1 to 14-7 generate heat from inside the insulator body 1 by passing current through heating wires 4 provided inside the insulator body 1. Therefore, the far-infrared heaters 14-1 to 14-7 can achieve a high temperature increase rate. Since the far-infrared heaters 14-1 to 14-7 can heat both sides, heat loss is small. The far-infrared heaters 14-1 to 14-7 have high heating efficiency because they emit high-density far-infrared energy. Since the far-infrared heaters 14-1 to 14-7 are flexible, there is no fear of cracking or deformation at high temperatures, and their dimensions can be easily set from small to large. Further, the far-infrared heaters 14-1 to 14-7 are thin and can heat both sides of the hot press steel plates 15-1 to 15-6.

Therefore, the far-infrared heaters 14-1 to 14-7 are arranged in the heating units 13-1 to 13-6 and the ceiling unit 19 of the multistage heating furnace, and require high heating efficiency and excellent temperature control in the furnace. It is preferably used as a heater for

The furnace frame 12 is a frame made of metal (for example, made of carbon steel) and arranged to surround the heating units 13-1 to 13-6 and the ceiling unit 19.

As shown in FIG. 3(b), the spaces in the heating units 13-1 to 13-6 all have a substantially rectangular outer shape in a horizontal plane (planar view). Each of the heating units 13-1 to 13-6 has blocks 16a, 16b, 16c, 16d, 16e, and 16f including a heat insulating material surrounding the space in a horizontal plane.

Each of the heating units 13-1 to 13-6 includes fixed blocks 16a, 16b, fixed blocks 16e, 16f, and lid blocks 16c, 16d. The fixed blocks 16a, 16b are fixedly arranged on two opposing sides of the rectangular outer shape. The fixed blocks 16a, 16b have an approximately rectangular parallelepiped outer shape. The fixed blocks 16e and 16f are fixedly arranged on the remaining two opposing sides. The fixed blocks 16e and 16f have an approximately rectangular parallelepiped outer shape. The lid blocks 16c and 16d are arranged to be openable and closable so as to engage with the fixed blocks 16e and 16f.

The lid blocks 16c and 16d are opened and closed by an opening/closing mechanism (not shown) such as a hinge mechanism or a slide mechanism. In the closed state, the lid blocks 16c, 16d contact the front and upper surfaces of the fixed blocks 16e, 16f, and the longitudinal end surfaces of the fixed blocks 16a, 16b. Thereby, the lid blocks 16c, 16d, together with the fixed blocks 16a, 16b and the fixed blocks 16e, 16f, insulate the internal spaces of the heating units 13-1 to 13-6 from the outside.

The heating units 13-1 to 13-6 are made of metal (for example, made of steel) and hold the fixed blocks 16a, 16b and the lid blocks 16c, 16d by surrounding the outer peripheries of the fixed blocks 16a, 16b and the lid blocks 16c, 16d, respectively. It has a furnace shell (iron shell) 18.

For example, the steel pedestals 17-1 to 17-7 are welded or fastened to a height that matches the height of each heating unit 13-1 to 13-6 and the ceiling unit 19 in the furnace frame 12. arranged by means. The pedestals 17-1 to 17-7 only need to have heat resistance to the extent that they will not be deformed by the heat transmitted from the fixed blocks 16a, 16b, and may be made of a metal material other than steel.

Although the fixed blocks 16a and 16b in the heating units 13-1 to 13-6 and the ceiling unit 19 are supported (mounted) and in contact with the pedestals 17-1 to 17-7 interposed between the furnace frame 12, It does not contact the furnace frame 12.

In this way, although the heating units 13-1 to 13-6 and the ceiling unit 19 having the spaces where the ambient temperature reaches 850 to 950° C. during operation contact the pedestals 17-1 to 17-7, Do not touch 12. Therefore, conduction of heat from the heating units 13-1 to 13-6 and the ceiling unit 19 to the furnace frame 12 is suppressed. Therefore, thermal expansion of the furnace frame 12 is suppressed.

For example, when the far-infrared multistage heating furnace 10 is in operation, the amount of displacement of the furnace frame 12 at the height of the center position in the height direction of the uppermost heating unit 13-6 is approximately 0.4 to 0.5 mm. It is. In this way, deformation of the furnace frame 12 due to thermal expansion is substantially eliminated.

Therefore, thermal stress is no longer generated in the furnace frame 12, resulting in deformation of the furnace frame 12 due to thermal expansion and contraction, repeated loads due to thermal stress, unstable operation, and a reduction in the life of the refractory that is the heat insulating material 16. Furthermore, damage such as cracks to the furnace frame 12 can be prevented, thereby significantly reducing maintenance costs and improving the operating rate of the far-infrared multi-stage heating furnace 10.

2. Support unit 24-1, 24-2 of far infrared heater 14-1
FIG. 6(a) is an explanatory diagram showing the heater support member (hereinafter simply referred to as "support member") 24-1 of the far-infrared heater 14-1 in the heating unit 13-1, and FIG. 6(b) is It is a top view of the heating unit 13-1, FIG. 6(c) is an explanatory diagram showing the arrangement relationship between the far-infrared heater 14-1 and the hot press steel plate 15-1, and FIG. 6(d) is FIG. 7 is an explanatory diagram showing another support unit 24-2 of the far-infrared heater 14-1 in the heating unit 13-1.

As shown in FIGS. 6(a) to 6(c), the far-infrared heater 14-1 is supported by the support unit 24-1 so as not to be horizontally bent.

The support unit 24-1 includes a first heater support beam 26 on which the far-infrared heater 14-1 is placed, and an end support member 27 that supports the end of the first heater support beam 26.

FIG. 7A is a longitudinal cross-sectional view showing the first heater support beam 26 cut along the longitudinal direction L of the first heater support beam 26. FIG. FIG. 7(b) is a cross-sectional view taken along line CC in FIG. 7(a).

Referring to FIGS. 7(a) and 7(b) in addition to FIGS. 6(a) to 6(d), the first heater support beam 26 is made of ceramic as a main component and is arranged horizontally. It is a beam. A plurality of first heater support beams 26 (four in FIGS. 6(a) to 6(d)) are arranged parallel to each other and spaced apart in one direction. The first heater support beam 26 is a rod-shaped member that extends straight in a longitudinal direction L that is perpendicular to the first direction when viewed from above. The far-infrared heater 14-1 is mounted on the ceramic member 41 of the four first heater support beams 26 and is arranged substantially horizontally. The far-infrared heater 14-1 is arranged inside an area surrounded by the fixed blocks 16a, 16b, 16e, and 16f in a horizontal plane.

The first heater support beam 26 includes a ceramic member 41 and a lid 42 attached to an end 41a of the ceramic member 41.

Preferably, the ceramic member 41 is made of silicon carbide ceramic. Silicon carbide-based ceramics (silicon carbide) are characterized by consistently maintaining mechanical properties up to temperatures above about 1400°C. That is, under the usage conditions of the heating furnace 10, the characteristics of the ceramic member 41 do not substantially change, and aging deterioration such as high temperature creep strain is extremely unlikely to occur. The characteristics of silicon carbide include a low density of about 3.07 to 3.15 g/ ^cm3 , high hardness of Hv≧22 GPa, high Young's modulus of about 380 MPa to 430 MPa, and high thermal conductivity of about 120 to 200 W/mK. is shown.

In this embodiment, the ceramic member 41 is a tube member having a predetermined wall thickness, and is formed into a square tube shape. More specifically, according to the present embodiment, the ceramic member 41 has an inner circumferential surface 41b and an outer circumferential surface 41c both having a rectangular shape in a longitudinal section (the cross section shown in FIG. 7(b)) perpendicular to the longitudinal direction L. be. The ceramic member 41 is vertically elongated in a cross section perpendicular to the longitudinal direction L, and the vertical length is longer than the horizontal length. As a result, the moment of inertia of the ceramic member 41 (first heater support beam 26) against a vertical load is increased, and the bending rigidity against a vertical load is high. Therefore, the deflection of the first heater support beam 26 is suppressed. Furthermore, the ceramic member 41 is formed into a square tube shape. Thereby, the ceramic member 41 can be made lightweight while increasing the bending rigidity of the ceramic member 41. Note that the ceramic member 41 is not limited to a square tube shape, but may be a round tube shape.

The intermediate portion of the ceramic member 41 in the longitudinal direction L is arranged in the internal space of the heating unit 13-1 and directly below the far-infrared heater 14-1, and the far-infrared heater 14-1 is placed on it. There is. Although not shown, it is preferable that an insulating insulator made of alumina or the like is placed on the upper part of the intermediate portion of the ceramic member 41, and that the far-infrared heater 14-1 is placed on this insulator. The insulator has, for example, a groove-shaped cross-sectional shape, and is fitted into the upper end of the ceramic member 41 and attached to the ceramic member 41, for example.

Through holes 29 are formed in the fixed blocks 16e and 16f. Both ends 41a, 41a of the ceramic member 41 of the first heater support beam 26 pass through the through hole 29 and are disposed outside the space to be heated in the heating unit 13-1.

Note that the structure of the first heater support beam 26 is similarly applied to the structure that supports the far-infrared heaters 14-2 to 14-7.

As explained above, the ceramic member 41 is provided on the first heater support beam 26 that supports the far-infrared heater 14-1. If the ceramic member 41 is used, even if the steel plate 15-1 for hot pressing is exposed to high heat from the far-infrared heater 14-1 for a long period of time during heating, high-temperature creep distortion can be extremely reduced. In particular, the strength at high temperatures can be significantly increased compared to the case where the far-infrared heater 14-1 is supported by a beam made of a heat-resistant alloy. Therefore, even when the heating furnace 10 is operated for a long period of time, it is possible to more reliably suppress the first heater support beam 26 supporting the far-infrared heater 14-1 from being bent.

In particular, by forming the ceramic member 41 with silicon carbide ceramic, the bending rigidity of the ceramic member 41 at high temperatures can be increased. Therefore, due to the planar far-infrared heater 14-1 thermally expanding and contracting in the horizontal direction due to temperature changes, a horizontal load acts on the ceramic member 41 of the first heater support beam 26 as a bending load. However, cracking of the ceramic member 41 can be more reliably suppressed.

Although both ends 41a, 41a of the ceramic member 41 do not need to be closed, they are preferably closed by a lid 42 containing a heat insulating material. The lid 42 is fixed to the ceramic member 41. Since the lid 42 is placed outside the heated space of the heating unit 13-1, it is not exposed to high temperatures. Therefore, there are no major restrictions on the material of the lid 42. The lid 42 may be made of the same material as the ceramic member 41, may be a ceramic member embedded with a heat insulating material such as glass wool, or may be made of a heat insulating material such as glass wool. The lid 42 may completely close the corresponding end 41a of the ceramic member 41, or may partially close the corresponding end 41a of the ceramic member 41 to the extent that gas flow between the inside and outside of the ceramic member 41 is suppressed.

In this manner, by providing the lid 42, outside air is prevented from entering the inside of the ceramic member 41. Therefore, generation of a temperature difference due to heat exchange between the inside and outside of the ceramic member 41 can be suppressed, and thermal stress in the ceramic member 41 can be reduced.

A pair of end support members 27 are provided and support both ends 41a, 41a of the first heater support beam 26. Each end support member 27 is a plate made of stainless steel, for example, and is supported by the pedestal 17-1. One end support member 27 is arranged adjacent to the fixed block 16e, and the other end support member 27 is arranged adjacent to the fixed block 16f.

The end support member 27 is arranged outside the space (steel plate storage area) surrounded by the fixed blocks 16a, 16b, 16e, and 16f, which are heat insulators.

In this way, the end support member 27 supports the plurality of first heater support beams 26 on the outside of the fixed blocks 16a, 16b, 16e, and 16f.

The end supports 27 are arranged on the outside of the blocks 16a-16f. Thereby, the end support member 27 is not exposed to the high heat in the inner space of the blocks 16a to 16f, and distortion caused by heat is suppressed.

Both ends of each first heater support beam 26 (each end 41a, 41a of the ceramic member 41) are connected to a slit or a through hole 27a (in FIG. 6A) formed in the end support member 27. (The upper half of the end support member 27 is not shown) is fitted and supported with a gap. More specifically, the number of through holes 27a of the end support member 27 is the same as the number of first heater support beams 26 (four in this embodiment). The end portion 41a of the ceramic member 41 of the corresponding first heater support beam 26 is fitted into each through-hole portion 27a. Thereby, the end support member 27 supports the end of the first heater support beam 26 so that the first heater support beam 26 can freely expand and contract in the longitudinal direction L of the first heater support beam 26 due to heat. ing. That is, the first heater support beam 26 is supported by the end support member 27 so as to be expandable and contractible in the longitudinal direction by thermal expansion or thermal contraction. Therefore, almost no thermal stress due to temperature changes occurs in the first heater support beam 26. In this embodiment, the through hole portion 27a of the end support member 27 is in contact with the ceramic member 41 and directly supports the ceramic member 41.

In a cross section perpendicular to the longitudinal direction L, the size of the through hole 27a of the end support member 27 is larger than the size of the outer peripheral surface 41c of the ceramic member 41. Therefore, only the bottom of the through-hole portion 27a contacts the ceramic member 41. In this way, if the through-hole portion 27a of the end support member 27 directly supports the ceramic member 41, the configuration of the first heater support beam 26 can be made simpler. Furthermore, by increasing the size of the through-hole portion 27a, it is possible to more reliably prevent the end support member 27 from impeding the thermal expansion and contraction of the ceramic member 41.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. In addition, below, the structure different from the above-mentioned embodiment is mainly demonstrated, and the same code|symbol is attached|subjected to the figure for the same structure, and detailed description is abbreviate|omitted.

For example, in the above embodiment, the ceramic member 41 is a hollow tube. However, this does not have to be the case. The ceramic member 41 may be solid instead of hollow.

[Modification example in which second heater support beam 28 is provided]
As shown in FIG. 6(d), a plurality of (two in FIG. 6(d)) second heater support beams 28 constitute another support unit 24-2 together with the first heater support beam 26. Good too. The plurality of second heater support beams 28 are arranged in a line toward one direction that intersects (perpendicularly intersects in the illustrated example) one direction in which the plurality of first heater support beams 26 are lined up. The second heater support beam 28 is made of the same ceramic material as the ceramic member 41 or a heat-resistant alloy. The second heater support beam 28 cooperates with the first heater support beam 26 to support the far-infrared heater 14-1.

In this modification, the second heater support beam 28 is a tube member having a predetermined wall thickness, and is formed into a square tube shape. More specifically, the second heater support beam 28 has a rectangular inner peripheral surface and an outer peripheral surface in a cross section perpendicular to the longitudinal direction of the second heater support beam 28 . The second heater support beam 28 is elongated in the vertical direction in the cross section, and the vertical length is longer than the horizontal length. As a result, the moment of inertia of the second heater support beam 28 against the vertical load is increased, and the bending rigidity against the vertical load is high. Therefore, the deflection of the second heater support beam 28 is suppressed.

A slit 28 a is formed in the second heater support beam 28 at a location where it intersects with the first heater support beam 26 . In this modification, four slits 28a are formed in one second heater support beam 28. The first heater support beam 26 is fitted into the slit 28a with a gap in the longitudinal direction of the second heater support beam 28. With this configuration, the second heater support beam 28 is supported by the first heater support beam 26. Thereby, the second heater support beam 28 is supported by the first heater support beam 26 such that it can expand and contract in the longitudinal direction of the second heater support beam 28 by thermal expansion or thermal contraction. Therefore, almost no thermal stress due to temperature changes occurs in the second heater support beam 28. Although not shown, it is preferable that an insulating insulator made of alumina or the like is placed on the intermediate portion of the ceramic member 41, and that the far-infrared heater 14-1 is placed on this insulator.

[Modified example of first heater support beam]
FIG. 8A is a plan view of a first heater support beam 26A according to a modification. FIG. 8(b) is a side view of the first heater support beam 26A. FIG. 9A is an enlarged view of a part of the end of the first heater support beam 26A. FIG. 9(b) is a cross-sectional view taken along line DD in FIG. 9(a).

8(a), FIG. 8(b), FIG. 9(a), and FIG. 9(b), the first heater support beam 26A includes a metal member as an intermediate body in addition to the ceramic member 41. It has a metal plate 43, which is an example.

In this modification, the end support member 27 indirectly supports the ceramic member 41 via the metal plate 43. Thereby, the ceramic member 41 does not need to come into direct contact with the end support member 27. Therefore, heat loss from the ceramic member 41 to the end support member 27 can be further reduced. Further, the metal plate 43 can function as a shock absorbing member against external force acting between the ceramic member 41 and the end support member 27, and can suppress damage to the ceramic member 41.

The metal plate 43 is provided at the end of the first heater support beam 26A and attached to the ceramic member 41. The metal plate 43 is formed by cutting a metal plate made of a heat-resistant alloy and having a predetermined thickness. The metal plates 43 are provided at both ends 41a, 41a of the ceramic member 41, respectively. The metal plate 43 is arranged in an upright position and is elongated in the longitudinal direction L of the ceramic member 41, and is inserted into the end portion 41a of the ceramic member 41. A part of the metal plate 43 (in this modification, about half of the base end side) is arranged in the space inside the ceramic member 41, and the remaining part of the metal plate 43 protrudes from the ceramic member 41 in the longitudinal direction L. ing. A portion of the metal plate 43 that protrudes from the ceramic member 41 is inserted into the through hole 27a of the end support member 27 and supported by the through hole 27a. The metal plate 43 is placed on the bottom of the through hole portion 27a. It is supported by the end support member 27 so as to be able to expand and contract in the longitudinal direction L due to heat.

The end portion 41a of the ceramic member 41 is passed through a through hole 29 formed in the fixed blocks 16e, 16f, and a gap is provided to the extent that the end portion 41a does not come into contact with the fixed blocks 16e, 16f.

In this embodiment, the metal plate 43 is prevented from coming into direct contact with the ceramic member 41 either at room temperature (20° C.) or when heating the hot press steel plate 15-1 (up to 950° C.). It is composed of Specifically, in the thickness direction of the metal plate 43, the dimension of the inner peripheral surface 41b of the ceramic member 41 is larger than the thickness of the metal plate 43. Further, the dimension of the inner circumferential surface 41b of the ceramic member 41 is larger than the dimension of the metal plate 43 in the height direction (vertical direction). Note that at the end portion 41a of the ceramic member 41, a gap between the metal plate 43 and the ceramic member 41 may be filled with a heat insulating material.

In this modification, the metal plate 43 and the ceramic member 41 are connected via pins 51 and 52. According to this configuration, the ceramic member 41 and the metal plate 43, which is a different material, can be connected with a simple configuration.

The pins 51 and 52 are, for example, metal members and are formed into round shaft shapes. In this embodiment, two pins 51 and 52 aligned in the longitudinal direction L connect the metal plate 43 and the ceramic member 41. The outer peripheral surfaces of both ends of each pin 51, 52 are formed into a cylindrical shape. A male threaded portion 53 is formed on the outer periphery of the intermediate portion of each pin 51, 52. On the other hand, each end portion 41a, 41a of the ceramic member 41 has a pair of pin holes 61, 61 through which one pin 51 passes, and a pair of pin holes 62, 62 through which the other pin 52 passes. There is. The pin holes 61, 61 are formed in the vertical wall portion of the ceramic member 41 and are coaxially aligned. Similarly, the pin holes 62, 62 are formed in the vertical wall portion of the ceramic member 41 and are coaxially aligned. The pin holes 61, 61 and the pin holes 62, 62 are lined up in the longitudinal direction L. In this modification, each pin hole 61, 61, 62, 62 has a cylindrical inner peripheral surface.

Further, the metal plate 43 is formed with a female threaded portion 71 and a female threaded portion 72 that are lined up in the longitudinal direction L. The female threaded portion 71 is arranged between the pin holes 61, 61. The female threaded portion 72 is arranged between the pin holes 62 , 62 .

One pin 51 is passed through pin holes 61, 61 and screwed into female threaded portion 71. The other pin 52 is passed through the pin holes 62 , 62 and screwed into the female threaded portion 72 . At room temperature, the diameter of the inner peripheral surface of the pin holes 61, 61 is made larger than the diameter of the cylindrical portion of the other pin 52, so that the pin holes 61, 61 are spaced apart from each other in the longitudinal direction L. There is. Similarly, at room temperature, the diameter of the inner peripheral surface of the pin holes 62, 62 is made larger than the diameter of the cylindrical portion of one pin 51, so that the pin holes 62, 62 have a gap in the longitudinal direction L. It's open. The above-mentioned gap regarding the pin hole 61 and the above-mentioned gap regarding the pin hole 62 are set to be the same. Thus, the ceramic member 41 has pin holes 61, 61, 62, 62 into which the pins 51, 52 are inserted so as to be movable relative to the pins 51, 52 in the longitudinal direction L. The gap between the pins 51, 52 and the corresponding pin holes 61, 61, 62, 62 in the longitudinal direction L at room temperature is determined by the gap between the space inside the heating unit 13-1 when the space inside the heating unit 13-1 changes from room temperature to hot temperature by the far-infrared heater 14-1. This is greater than the amount of relative displacement between each pin 51, 52 and the corresponding pin hole 61, 61, 62, 62 when the temperature changes to the heating temperature of the press steel plate 15-1 (maximum 950° C.). That is, the pins 51 and 52 are configured not to press the pin holes 61 and 62 in the longitudinal direction L even when the hot press steel plate 15-1 is heated.

By providing such a gap, the pins 51 and 52 are strongly pressed against the inner peripheral surfaces of the corresponding pin holes 61 and 62 of the ceramic member 41 when the hot press steel plate 15-1 is heated. Therefore, damage to the ceramic member 41 can be suppressed.

In addition, in this modification, the temperature of the ceramic member 41 at the temperature of the space inside the heating unit 13-1 (maximum 950° C.) when the far-infrared heater 14-1 is heating the hot press steel plate 15-1. The bending strength is made higher than that of the metal plate 43. For example, by appropriately setting the thickness of the ceramic member 41 and the thickness of the metal plate 43, such a relationship in bending strength is established. The bending strength of the metal plate 43 at high temperatures is preferably one-third or less of the bending strength of the ceramic member 41, although it depends on the degree of the assumed impact load. Note that the bending strength here refers to a bending load that acts in the horizontal direction. This bending strength is determined, for example, by using the contact position between the metal plate 43 and the end support member 27 as a fulcrum, the longitudinal center position of the ceramic member 41 as a point of force, and applying a load in a direction perpendicular to the longitudinal direction L in a plan view. This refers to the bending strength when

With such a bending strength relationship, even if some kind of impact load is applied to the ceramic member 41 from a conveyance device from outside the furnace or a workpiece such as the hot press steel plate 15-1, repair by straightening is easy. By bending the metal plate 43, damage to the expensive ceramic member 41 can be suppressed.

In addition, in the above-mentioned modification, the form in which the pin holes 61, 61, 62, and 62 are round holes was explained as an example. However, this does not have to be the case. As shown in FIG. 10A for explaining a modification of the pin holes, the pin holes 61 and 62 may be long holes elongated in the longitudinal direction L.

Further, in the above-described configuration, the pin holes 61 and 62 are formed in the ceramic member 41, and the female screw portions 71 and 72 are formed in the metal plate 43. However, this does not have to be the case. For example, as shown in FIG. 10(b) for explaining a modification of the arrangement of the pins 51, 52, pin holes 61, 62 are formed in both the ceramic member 41 and the metal plate 43, and the pins 51, 52 are inserted into the ceramic member 41 and the metal plate 43. May be placed. Also in this case, the gaps between the pins 51, 52 and the corresponding pin holes 61, 62 are set so as to have the above-mentioned relationship.

In addition, although the said modification example demonstrated the form in which two pins were provided in the edge part 41a of the ceramic member 41, it does not have to be this way. The number of pins 51 and 52 provided on the end portion 41a of the ceramic member 41 may be one, or may be three or more. Alternatively, the configuration may be such that the metal plate 43 is simply inserted into the end portion 41a of the ceramic member 41 without using the pins 51 and 52.

Further, in the above-described embodiment, the metal plate 43 is inserted into the end portion 41a of the ceramic member 41, but this may not be the case. For example, a metal block may be used instead of the metal plate 43, or an intermediate body connecting the ceramic member 41 and the end support member 27 may be made of a material other than metal.

The present invention can be widely applied as a far-infrared multistage heating furnace for hot pressing steel sheets.

1 Insulator body 2 Heating wire through hole 4 Heating wire 10 Far-infrared multi-stage heating furnace 13-1 to 13-6 Heating unit 14-1 to 14-7 Far-infrared heater 15-1 to 15-6 Steel plate for hot pressing 16a to 16f Block 26 First heater support beam (heater support beam)
27 End support material 27a End support material through-hole portion 28 Second heater support beam 41 Ceramic member 41a End portion 42 of heater support beam Lid 43 Metal plate (intermediate body, metal member)
51, 52 Pins 61, 62 Pin hole L Longitudinal direction

Claims (14)

A block including a heat insulating material arranged to surround a horizontal surface of a space that accommodates a steel plate for hot pressing, and a block disposed above and below a portion of the space where the steel plate for hot pressing is arranged and heated. A far-infrared multi-stage heating furnace including a heating unit having a far-infrared heater that heats the hot-pressing steel plate,
comprising a plurality of heater support beams supporting the far-infrared heater,
Each of the heater support beams includes a ceramic member;
Each of the heater support beams is made of the ceramic member in the space,
The ceramic member is hollow or solid made of silicon carbide ceramic,
A steel plate for hot pressing, further comprising an end support member that supports an end of each of the heater support beams so that each of the heater support beams can freely expand and contract in the longitudinal direction due to heat. Far-infrared multi-stage heating furnace. The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 1, wherein the end support material indirectly supports the ceramic member via an intermediate body. The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 2, wherein the intermediate body includes a metal member attached to an end of the ceramic member . The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 3, wherein the metal member is a metal plate and is inserted into the ceramic member. A bending strength of the ceramic member is higher than a bending strength of the metal member at a temperature of 850° C. to 950° C. in the space when the far-infrared heater heats the hot pressing steel plate. A far-infrared multistage heating furnace for hot pressing steel sheets according to claim 3 or 4. The far-infrared multistage heating furnace for hot pressing steel sheets according to any one of claims 3 to 5, wherein the metal member and the ceramic member are connected via a pin. At least one of the metal member and the ceramic member has a pin hole into which the pin is inserted so as to be movable relative to the pin in the longitudinal direction, and the pin and the pin hole in the longitudinal direction are at room temperature. The gap is greater than or equal to the amount of relative displacement between the pin and the pin hole when the space changes from room temperature to 850°C to 950°C, which is the temperature when the hot pressing steel plate is heated by the far infrared heater. A far-infrared multistage heating furnace for hot pressing steel sheets according to claim 6. The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 1, wherein the end support directly supports the ceramic member. The ceramic member is configured to be hollow,
The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 8 , wherein the end portion of the ceramic member is closed with a lid including a heat insulating material. The end support member has a through hole portion through which the ceramic member passes and receives the ceramic member;
The far-infrared multistage heating furnace for hot pressing steel sheets according to claim 8 or 9 , wherein the size of the through hole portion is larger than the size of the ceramic member in a cross section perpendicular to the longitudinal direction. . The far-infrared multistage heating furnace for hot-pressing steel sheets according to any one of claims 1 to 10 , wherein the end support material is arranged outside the block. The far-infrared heater has a planar structure in which a plurality of insulator bodies, each of which is a sintered body of far-infrared radiation emitting ceramics, are lined up vertically and horizontally. The far-infrared ray type multistage steel plate for hot pressing according to any one of claims 1 to 11 , which has flexibility by being movably connected to each other by heating wires inserted into the heating wire through holes. Type heating furnace. The ceramic member is formed in the shape of a hollow rectangular square tube, and both an inner circumferential surface and an outer circumferential surface are rectangular when viewed in the longitudinal direction of the square tube, and when viewed in the longitudinal direction of the square tube , The far-infrared multi-stage heating furnace for hot pressing steel sheets according to any one of claims 1 to 12, which is formed in a vertically elongated manner. The plurality of heater support beams are arranged parallel to each other while being spaced apart from each other in one direction,
further comprising a plurality of second heater support beams that are arranged in line in another direction intersecting the one direction and support the far-infrared heater,
Each of the second heater support beams is supported by a plurality of the heater support beams so that each of the second heater support beams can freely expand and contract in the longitudinal direction of the second heater support beams due to heat. A far-infrared multistage heating furnace for hot pressing steel sheets according to any one of claims 1 to 13.

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