JPH08178537A - Vertical muffling furnace - Google Patents

Abstract

PURPOSE: To provide a vertical muffling furnace capable of restricting an amount of deformation near a lower end of a muffle to a small amount. CONSTITUTION: In a vertical muffling furnace in which a muffle 3 is passed through a main body 2 of the furnace and hung there, a side wall surface 3a of the muffle 3 fitted to a muffle passing-through hole 23 arranged at a bottom part 2a of the furnace of the main body 2 of the furnace is provided with a plurality of groove-like adjusting machining sections 20a, 20b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical muffle furnace for continuously heat treating strip material.

[0002]

2. Description of the Related Art As a vertical muffle furnace of this type, generally, a cylindrical muffle in which an upward traveling strip penetrates is hung so as to penetrate a cylindrical furnace body, and a muffle between the furnace body and the muffle is suspended. Burning is performed in the combustion chamber by a burner, and heat treatment such as bright annealing of the strip is performed in a reducing or non-oxidizing atmosphere gas filled in the muffle, and the combustion gas after the muffle heating is burned by an exhaust fan. A furnace configured to suck and discharge to the outside is used.

In the side wall surface portion of the muffle which penetrates the muffle through hole provided in the furnace bottom portion of the furnace body, the upper side portion of the muffle through hole has a high-temperature atmosphere (for example, 1000 to 1000) in the furnace.
(1100 ° C.), the lower parts of the through holes are exposed to the low temperature atmosphere outside the furnace (for example, room temperature) respectively, so that a large temperature gradient is generated in the side wall surface part and the combustion exhaust gas discharge port is formed in the side wall of the bottom part of the furnace body. Since the muffle side wall near the discharge port has an uneven temperature distribution in the circumferential direction, the thermal stress on the side wall surface of the muffle becomes excessive and the side wall surface and its vicinity are greatly deformed. Moreover, the above deformation is accumulated due to the repeated heating and cooling of the muffle accompanying the repeated operation of the furnace, which causes various problems such as the generation of cracks in the side wall of the muffle and the outflow of atmospheric gas in the muffle. there were. In addition, since the muffle is generally made of high-grade steel containing about 72% Ni, it is very expensive. If the life of the muffle is short, not only the productivity of the equipment will decrease, but also a large amount of money is required to purchase a spare muffle, This was a factor in increasing the production cost of the product strip.

[0004]

In order to prevent the deformation of the muffle, a plurality of heat-resistant steel strips extending in the vertical direction are welded to the inner surface of the side wall of the muffle at predetermined intervals. Then, it was attempted to reinforce the side wall surface part, but cracks occurred in the weld where stress concentrates due to repeated muffle heating and cooling, the strip strips and loses the deformation prevention effect. There was a problem that cracks were also generated on the muffle side of the part.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a vertical muffle furnace capable of suppressing the deformation near the lower end of the muffle to a small amount.

[0006]

A vertical muffle furnace according to the present invention is a vertical muffle furnace in which a muffle is suspended by penetrating the furnace body and fitted in a muffle through hole provided in the bottom of the furnace body. A plurality of groove-shaped drawn portions are provided on the side wall surface portion of the muffle.

In the present invention, the range in the longitudinal direction of the muffle in which the groove-shaped drawn portion is provided is the range of the side wall surface portion of the muffle fitted in the muffle through hole, that is, the range of the muffle side wall surface facing the inner peripheral surface of the muffle through hole ( The thickness range of the furnace bottom of the furnace body), but the length of the muffle changes due to creep deformation due to the temperature increase / decrease during operation and its own weight under high temperature, so the above muffle fluctuates accordingly. In the entire range of the muffle side wall surface facing the inner peripheral surface of the through hole, that is, in the furnace bottom thickness range of the furnace body at the start of use of the new muffle,
It is preferable to set it in a range in which the muffle extension dimension due to the temperature rise and the accumulated creep deformation length until the muffle is replaced are added. Furthermore, if the groove-shaped drawing portion is provided up to this range, the range in which the combustion exhaust gas outlet provided in the furnace body is opened (the vertical distance from the upper surface of the furnace bottom to the upper edge of the outlet) is added. It is particularly preferable because deformation of the muffle due to nonuniform temperature distribution in the muffle circumferential direction due to the combustion exhaust gas outlet can be prevented.

Further, if the groove-shaped drawn portion in the present invention is provided on the side wall surface portion of the muffle so as to extend in at least one of the longitudinal direction and the circumferential direction of the muffle, the above-mentioned flat plate for forming the muffle is formed. This is particularly preferable because it is easy to perform the cylindrical bending process after the drawing process portion is provided.

The drawn portion may be provided so as to bulge toward the inner diameter side of the muffle, or may be provided so as to bulge toward the outer diameter side of the muffle, but it may be provided so as to bulge toward the inner diameter side. This is preferable because the muffle through hole provided in the furnace bottom portion of the furnace body can have a simple cylindrical shape.

[0010]

In the vertical muffle furnace of the present invention, the plurality of groove-shaped drawn portions provided on the side wall surface portion of the muffle fitted into the muffle through-holes form a simple cylindrical muffle without the drawn portion. In comparison, the number of cross-sectional shapes of the muffle side wall surface portion is increased to improve buckling and bending strength, the thermal stress of the side wall surface portion is reduced, and the deformation due to the thermal stress is suppressed. Since the stress concentration in the drawn portion is gentler than the stress concentration in the welded portion when reinforcing the welded structure, the occurrence of cracks can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the figure, 1 is a vertical muffle furnace, and a furnace body 2
And a muffle 3 penetrating the furnace body 2, the furnace body 2 is erected on a base 4, and the upper end of the muffle 3 is suspended by a pedestal 5. 6 is a slit-shaped charging port through which the strip 7 passes, 8 is a refractory material filled and fixed inside the muffle 3 to form the charging port 6, and 9 is a seal attached to the lower end surface of the muffle 3. It is a device. Further, 10 is an extraction port, to which a chamber 12 that forms a cooling zone is connected, and 11 is a refractory material that is filled and fixed inside the muffle 3 to form the extraction port 10. Reference numeral 13 denotes a blower for exhausting combustion gas, which is the bottom 2a of the furnace main body 2.
Two exhaust ports 14 formed in the side wall of the furnace body 2 in the vicinity of
14 is connected via a duct 15. Further, a burner for heating is provided on the wall portion of the furnace body 2, but its illustration is omitted. Reference numeral 16 is a bellows-shaped gas seal material that can be expanded and contracted in the vertical direction.
The upper end and the lower end are attached to the lower end of each.

On the other hand, 20 is a side wall surface portion 3 below the muffle 3.
In the groove-shaped drawing portion provided in a, a plurality of (16 in this embodiment) extending in the longitudinal direction (vertical direction) of the muffle.
The groove-shaped drawn portion 20a and two groove-shaped drawn portions 20b that intersect with the groove-shaped drawn portion 20a and extend in the circumferential direction of the muffle 3. This drawing part 20 is a muffle 3
Shallow angular groove shape bulging toward the inner diameter side (width W =
100 mm, depth D = 20 mm), the lower cylinder 21 constituting the muffle 3 is formed by drawing on the side wall plate 22 made of heat-resistant steel plate before cylindrical bending, and then subjected to cylindrical bending. The muffle 3 is formed by butt welding with another cylinder.

As shown in FIG. 2, the groove-shaped drawing portion 20 extends from the position corresponding to the lower end (the lower surface of the furnace bottom 2a) of the muffle through hole 23 of the new muffle 3 at room temperature to the furnace bottom 2a. Is provided over a range L up to a position where the sum S of the muffle extension dimension due to the temperature rise of the muffle 3 and the accumulated creep deformation length (expected value) before the muffle replacement is added to the thickness t of It may be provided in a wider range or in a slightly narrower range. In particular, the drawn portion 2 extends over the range in which the height H of the exhaust port 14 is added to the above range L.
When 0 is provided, the stress in the lower part of the muffle 3 due to the non-uniform temperature distribution in the muffle circumferential direction due to the existence of the exhaust port 14 is absorbed in each groove-shaped portion provided in advance for each part, and it is as if the bellows method is used. The expansion tube acts as if it absorbs expansion and contraction, and prevents the deformation of the entire lower part of the muffle, which prevents large deformation until the muffle is replaced, which is particularly preferable.

In the vertical muffle furnace 1 having the above structure,
The groove-shaped drawn portion 20 increases the bending strength and the buckling strength of the side wall surface portion 3a of the muffle, and at the same time, the thermal stress generated in the side wall surface portion 3a fitted into the muffle through hole 23 is reduced, so that the side wall surface portion 3a of the muffle is reduced. The deformation is suppressed.

The present invention is not limited to the above embodiment. For example, as the groove-shaped drawn portion, the drawn portion 20a of the above embodiment extending in the longitudinal direction of the muffle is provided.
Only, or only the drawn portion 20b extending in the circumferential direction (the number may be increased appropriately), and FIG.
As shown in Fig. 6, a short drawn portion 20c extending in the muffle circumferential direction is provided so as not to be continuous with the longitudinal drawn portion 20a, or as shown in Fig. 6, a drawn portion 20c extending in the muffle circumferential direction is provided. It may be provided intermittently in the circumferential direction, or a drawn portion extending in a direction inclined with respect to the longitudinal direction of the muffle such as an X-shaped arrangement may be provided. Further, the cross-sectional shape of the groove-shaped drawn portion may be a shape other than the above-mentioned square groove shape, such as a round groove shape.

In the above embodiment, the muffle through hole 23
As a seal device of the present invention, a bellows-shaped gas seal material 16 that expands and contracts in the vertical direction is used by being attached between the lower end portion of the furnace body 2 and the lower end portion of the muffle 3, so that the muffle through hole 23 and the muffle It has a great merit that it is possible to prevent the side wall surface portion 3a of the muffle 3 from being non-uniformly cooled by the cold air entering the furnace body 2 through the gap of 3 and increasing its distortion. Another type of sealing device is one in which a gas seal material made of wool or the like is arranged in a ring shape so as to surround the exposed outer peripheral surface of the muffle 3 on the lower surface of the furnace bottom portion 2a of the furnace body 2 and to make sliding contact therewith. A seal device may be used.

[0017]

As described above, according to the present invention,
Large deformation due to thermal stress of the side wall surface portion is suppressed by a plurality of groove-shaped drawing portions provided on the side wall surface portion of the muffle that fits into the muffle through hole, and deformation near the lower end portion of the muffle can be suppressed to a small amount. A vertical muffle furnace with high durability against deformation can be obtained, and the life of the expensive muffle is extended, which is economical. Further, since the muffle exchange period is extended, continuous production is continued, and productivity is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vertical muffle according to an embodiment of the present invention.

FIG. 2 is a front view of a lower portion of the muffle shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is a view corresponding to FIG. 2, showing another embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 2 showing still another embodiment of the present invention.

[Explanation of symbols]

1 ... Vertical muffle furnace, 2 ... Furnace body, 3 ... Muffle, 3a
... Side wall surface portion, 20 ... Drawing processing portion, 20a ... Drawing processing portion,
20b ... Drawing processing part, 20c ... Drawing processing part, 23 ... Muffle through hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Tanaka 2-19-16 Kogiso, Yokkaichi-shi, Mie

Claims (2)

[Claims] 1. A vertical muffle furnace in which a muffle is suspended through a furnace body, and a plurality of groove shapes are formed in a side wall surface portion of the muffle that is fitted into a muffle through hole provided in a furnace bottom portion of the furnace body. Vertical muffle furnace, which is equipped with a drawing part. 2. The vertical muffle furnace according to claim 1, wherein the groove-shaped drawn portion extends in at least one of a longitudinal direction and a circumferential direction of the muffle.