JPH07103671A - Ultrasonic wave guide - Google Patents

Abstract

PURPOSE:To restrict occurrence of noise echo and carry out accurate measurement. CONSTITUTION:A rod-like ultrasonic wave guide 14 arranged inside a refractory material or its circumferential edge for forming a molten metal container of a molten metal processing furnace is covered at its outer circumference with a solid or unshaped covering member 24. The solid covering member and the wave guide in the ultra-sonic wave guide can be connected at one location in a longitudinal direction or at a plurality of locations through compression bonding, adhesion or welding and the like. In addition, the refractory material can have an aeration structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a porous plug used for a molten metal container such as a ladle, and more particularly to a structure of a porous plug capable of measuring a residual height.

[0002]

2. Description of the Related Art Porous plugs are arranged, for example, at the bottom of a molten metal container such as a ladle and are used for blowing gas into molten metal. The porous plug is formed of a highly breathable refractory material, and its tip is exposed in the molten metal. For this reason, the tip of the porous plug is burnt away by light heat, and the remaining height is gradually shortened. If the length of the porous plug becomes shorter than the limit value, the molten metal leaks from the mounting portion of the porous plug, resulting in serious damage.

Since the melted state of the porous plug in the container cannot be directly visually confirmed, it is necessary to replace the porous plug by estimating the melted state from the operating time. However, the amount of the porous plug melted away varies depending on various operating conditions, and therefore, it is necessary to replace the porous plug early in consideration of safety. For this reason, although it is originally still usable, it is exchanged, and there is a problem that the economy is poor.

On the other hand, in various furnaces such as blast furnaces and heating furnaces,
A method of detecting the falling of the furnace wall using the reflection of ultrasonic waves is
It is disclosed in JP-A-55-162593. In the method for detecting the falling of the furnace wall described in the publication, a detection rod is embedded in the furnace wall in the horizontal direction, ultrasonic waves are incident on the detection rod from outside the furnace, and a change occurs in the reflected signal, which is caused by the falling of the furnace wall. The bent state of the detection rod is detected, and the falling state of the furnace wall is known from this.

However, in the method of detecting the falling of the furnace wall described in the above publication, the falling state of the furnace wall is detected from the bent state of the detecting rod, so that the detecting rod does not bend despite the falling of the furnace wall. If not, it cannot be detected. Also,
Since the detection rod bends due to the weight of the removed furnace wall, the arrangement direction of the detection rod is limited to the horizontal direction. Furthermore, when the detection rod comes into contact with the molten metal as the furnace wall falls off,
The temperature of the detection rod becomes extremely high, and the ultrasonic wave propagation characteristics of the detection rod deteriorate, making it impossible to perform accurate measurement.
In addition, the state where the detection rod is completely buried in the furnace wall,
Since the temperature of the detection rod changes when the detection rod is exposed to the molten metal, the ultrasonic wave propagation characteristics also change, which also makes accurate measurement difficult. Therefore, the method for detecting falling of the furnace wall described in the above publication cannot be used as it is for detecting the remaining height of the porous plug.

In order to solve such a problem, the applicant of the present application previously arranged a waveguide rod-like body for ultrasonic measurement, which is melted away at the same degree as the porous plug, integrally with the porous plug. A porous plug for a molten metal container having a structure has been proposed (Japanese Patent Application No. 4-95586). FIG. 4 shows an example thereof. In the figure, a perm brick 2 and a ladle bottom brick 3 are laminated on a ladle bottom plate 1. These ladle bottom plate 1, perm brick 2 and ladle bottom brick 3 are formed with through holes 4 for penetrating a porous plug, and the portion corresponding to the through hole 4 of the ladle bottom brick 3 has a conical shape. A brick 6 having a through hole 5 is provided. Further, a receiving member 7 for detachably attaching a porous plug is fixed to the lower surface of a portion of the ladle bottom plate 1 corresponding to the through hole 4 by welding or the like.

The porous plug 8 is a round rod-shaped porous element 9 made of a refractory material such as high-alumina brick having high air permeability, a substantially conical castable element 10 provided on the outer periphery of the porous element 9, and the castable element. A plug main body 12 is provided, which includes a substantially conical metal case 11 that covers in an airtight state except the upper end portion of the metal casing 10. A gas blowing pipe 13 is connected to the bottom surface of the metal case 11.

Further, inside the porous plug 8, there is provided a waveguide rod 14 for ultrasonic measurement, which has good propagation characteristics for ultrasonic waves and is melted away at the same degree as the porous plug 8. It is arranged integrally. The waveguide rod 14 is pulled out downward through a through hole 11a formed in the bottom of the metal case 11. In the figure, reference numeral 15 is a plug receiving brick, 16 is a height adjusting disk, 17 is a holding metal object,
Reference numeral 18 denotes an ultrasonic probe, which is driven by an ultrasonic length measuring device (not shown).

According to this, the remaining height can be accurately known even for the porous plug provided at the bottom of the container, and it is possible to prevent erroneous judgment of the usage limit from causing serious damage. it can. Further, since the waveguide rod-shaped body is provided integrally with the porous plug, the waveguide rod-shaped body is sufficiently cooled by the gas passing through the porous plug, and the good ultrasonic propagation characteristics of the waveguide rod-shaped body are maintained. It is possible to know the remaining height accurately even in the environment.

[0010]

However, in the porous plug according to the above proposal, when the waveguide rod-shaped body 14 and the refractory material 10 surrounding the waveguide-shaped body 14 come into contact with each other in a state of propagating ultrasonic waves, coarse echo is generated. And adversely affect measurement.

That is, when arranging the waveguide rod 14 inside or around the refractory, the irregular refractory material 10 such as mortar or castable material is used. Leakage and diffusion of ultrasonic waves into the material 10, and vice versa, intrusion of echo occurs, which makes it difficult or impossible to clearly capture the echo from the end face of the waveguide 14.

An object to be solved by the present invention is to provide an ultrasonic wave guide which suppresses the generation of miscellaneous echoes and enables accurate measurement.

[0013]

In order to solve the above-mentioned problems, the ultrasonic wave guide of the present invention is a rod-shaped member disposed inside or around a refractory material forming a molten metal container or a molten metal processing furnace. In the above ultrasonic waveguide, the outer circumference of the ultrasonic waveguide is covered with a solid or amorphous coating.

In this ultrasonic wave guide, the solid covering and the wave guide may be joined by pressure bonding, adhesion or fusion at a single or a plurality of points in the length direction. it can. Further, the refractory material may have a ventilation structure.

[0015]

The coating which covers the outer circumference of the rod-shaped ultrasonic wave guide serves to block the ultrasonic wave from propagating between the wave guide and the amorphous refractory material. There is a space between the waveguide and the solid coating, and ultrasonic waves do not propagate and diffuse.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on the embodiments shown in the drawings. FIG. 1 shows two examples of the structure of the porous plug 8 for a molten metal container, (a) shows an example in which the waveguide rod-shaped body 14 is arranged at the center of the porous element 9,
(B) shows an example in which the distal end of the waveguide rod 14 is bent in the castable 10 and the proximal end is bent so as to be exposed in the gas blowing pipe 13. Since other configurations are the same as those of the conventional example of FIG. 4, description thereof will be omitted.

As shown in FIG. 2, the waveguide rod-shaped body 14, which is a feature of the present invention, is covered with a tubular covering body 24 on the outer periphery thereof.

As the material of the covering body 24, a solid material and an amorphous material can be used. As the solid material, metal, particularly stainless steel tube, ceramics, especially alumina sintered tube, glass, especially quartz glass tube, synthetic resin,
In particular, a vinyl chloride tube can be used. In addition, synthetic resin tape, paper tape, cloth tape, ceramic fiber tape, or rubber tape can be used as the indeterminate character.

The solid coating serves to block the ultrasonic wave from propagating between the waveguide and the amorphous refractory material. There is a space between the waveguide and the solid coating, and ultrasonic waves do not propagate and diffuse. Further, by filling a part of this space with a fine particle solid (for example, sand, glass powder, ceramic powder, metal powder), or an organic or inorganic fibrous body, it is possible to stabilize the position of the waveguide, It is possible to prevent the molten metal from penetrating through this space and leaking to the outside or disturbing the measurement.

The amorphous coating adheres closely to the waveguide rod 14, but is deteriorated and burned by the heat of the high temperature atmosphere at the time of use to form a vacant portion around the waveguide, greatly reducing the propagation of ultrasonic waves. Let's reach a similar purpose.

Solid tubular coating 24 and waveguide bar 14
The difference between the inner and outer diameters is 0.01 to 1 mm, preferably 0.1 to 0.5 mm. This is to prevent molten metal from entering or leaking.

Further, as shown in FIG. 3, the diameter of the covering 24 is reduced at a plurality of locations along the way and joined to the outer periphery of the waveguide rod 14 to form a joint A, and at other portions, a gap B is formed. Is to occur. By forming the joint portion A at a plurality of places, an echo due to this portion is obtained,
The remaining height of the porous plug 8 can be measured by an ultrasonic length measuring device.

Conventionally, a method of obtaining a similar echo by making a notch in a waveguide was generally used, but the advantage of using a junction structure instead of the notch is as follows. (1) A slight echo indicating an intermediate position can be added without damaging the main echo from the tip end surface, which is originally necessary because the cross section of the waveguide is not damaged. (2) The intensity of the echo indicating the intermediate position can be adjusted by changing the joining method. (3) In the coating, the waveguide moves in the longitudinal direction,
It can be prevented from falling off by joining.

The method of joining the waveguide rod-shaped body 14 and the tubular coating body 24 is performed by tightening and crimping the tubular coating body 24 to the waveguide rod-shaped body 14. At this time, heating is more effective. Alternatively, it is adhered or glued with a ceramic adhesive such as enamel or the like. As another method, tighten and energize to locally fuse (spot welding)
Both are joined by performing.

As for the shape of the waveguide rod body 14, it is important that the measuring end face 14e is in contact with the probe 18 reliably, and a shape with a rounded convex shape is preferable to a flat shape. Even if the surface of the probe 18 is slightly inclined and comes into contact with the probe 18, the transmission and reception of ultrasonic waves is advantageous.

[0026]

As described above, the present invention has the following effects.

(1) The cover serves to block the ultrasonic wave from propagating between the waveguide and the amorphous refractory material. There is a space between the waveguide and the solid coating, and ultrasonic waves do not propagate and diffuse. This makes it possible to accurately perform ultrasonic measurement.

(2) Originally, a solid coating is used to create a space around the waveguide for the purpose of blocking the ultrasonic waves, but the two are joined at a specific position to intentionally break the blocking. Can generate an echo indicating the position.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a molten metal container porous plug to which an ultrasonic waveguide of the present invention is attached.

FIG. 2 is a partially cutaway perspective view showing the structure of an ultrasonic waveguide according to the present invention.

FIG. 3 is a cross-sectional view of a joint portion of an ultrasonic waveguide body according to the present invention.

FIG. 4 is a cross-sectional view showing an example of a conventional melting container to which a porous plug is attached.

[Explanation of symbols]

1 ladle bottom plate, 2 perm bricks, 3 ladle bottom bricks,
4 Through holes, 5 Through holes, 6 Receptacles, 7 Receptacles, 8 Porous plugs, 9 Porous elements, 1
0 castable, 11 metal case, 12 plug body, 13 gas blowing pipe, 14 waveguide rod,
15 plug bricks, 16 height adjustment discs, 1
7 Presser hardware, 18 Probe, 24 Cover

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F27D 3/16 Z 7141-4K G01B 17/00 A

Claims (3)

[Claims] 1. A rod-shaped ultrasonic waveguide disposed inside or at a peripheral portion of a refractory forming a molten metal container or a molten metal treatment furnace, wherein the outer periphery of the ultrasonic waveguide is solid or amorphous. An ultrasonic waveguide characterized by being coated with the above coating. 2. The ultrasonic waveguide according to claim 1, wherein the solid coating and the waveguide are joined by pressure bonding, adhesion or fusion at a single location or a plurality of locations in the length direction. . 3. The refractory material has a ventilation structure.
The described ultrasonic waveguide.