JPS6126353Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a ceramic roller in which ceramic and metal are fitted and connected.

In recent years, ceramics have begun to be used as mechanical parts in high-temperature devices in place of metals, and one example is rotating bodies such as rollers.

Conventionally, metal rollers have been used as rollers for conveying high-temperature furnaces or rollers for conveying steel ingots, either as they are or after being water-cooled.

However, metal rollers have a limit to their operating temperature, and if they are used beyond that operating temperature, special measures such as cooling must be taken, and from the standpoint of heat loss and the occurrence of so-called skid marks, they are It is undesirable.

Therefore, engineering ceramics mainly made of silicon nitride (Si ₃ N ₄ ) and silicon carbide (SiC), which have been recently developed and put into practical use and have excellent heat resistance and high-temperature strength, are used for the above rollers, etc. However, the problem here is not only the characteristics of the ceramic roller itself but also how to maintain this ceramic roller in the drive device.

In the case of a metal roller, it is usually connected to a driving device by directly connecting it to a synchronous motor, or by having a pulley or gear attached to the end of the roller and driving it by a belt or the like.

However, pulleys or gears made of ceramics have not yet been put to practical use.
It is necessary to connect these driving members made of metal and the ceramic roller inside or outside the furnace.

However, when connecting outside the furnace, there are problems such as thermal stress fracture due to a large temperature difference in the axial direction between the inside and outside of the ceramic, and difficulties in manufacturing ceramic rollers.On the other hand, when connecting inside the furnace, there are problems with the metal Breakage due to differences in physical properties such as the coefficient of thermal expansion of ceramics has become a problem.

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The inventors of the present invention conducted various studies based on these points of view, and succeeded in realizing the use of a rotating body made of ceramics by improving the connection structure with a metal rotating body.

That is, in the present invention, the rotating shaft made of ceramics is fitted on the inside and the rotating shaft made of metal is placed on the outside, abutting parts are formed in the axial direction on both rotating shafts, and a heat insulating layer is provided on the abutting parts. This is a ceramic roller formed by interposing the two rotary shafts, and furthermore, a ceramic roller formed by forming the fitting state of the portion where both rotating shafts fit into a specific shape.

According to the present invention, even though compressive stress is applied to the ceramic rotating body, tensile stress is low, which prevents destruction of the ceramic, and allows the use of highly durable ceramic rollers without the adverse effects of thermal expansion differences. It is possible.

The present invention will be explained below with reference to the drawings.

As shown in FIG. 1, the present invention basically comprises a rotating shaft part 1 made of ceramics, a rotating shaft part 2 made of metal, and a heat insulating material 3.

Here, the ceramic rotating shaft part 1 and the metal rotating shaft part 2 are connected so that the metal rotating shaft part 2 is on the outside and the ceramic rotating shaft part 1 is on the inside at the connecting part between them. Part 1
The outer periphery 1a of the metal rotating shaft portion 2 and the inner periphery 2a of the metal rotating shaft portion 2 are fitted together.

By doing this, even if the ceramic expands during use at high temperatures, the expansion can be suppressed by cooling the outer metal part with water, or compressive force can be applied from the outside in the axial direction via a spring. If you do this, the two will fit together strongly and there will be no wobbling during rotation. Compressive stress acts on ceramics, but tensile stress will be low, and the durability of ceramics, which is extremely strong against compressive stress, can be fully utilized. Become something.

In FIG. 1, numeral 4 is a hollow portion when water cooling is required, for example. In such a structure for connecting two rotating shafts, an abutting portion is formed so that the end surface 1b of the inner ceramic rotating shaft contacts the inner end surface 2b of the fitting groove of the metal rotating shaft. Since this abutment part presses the ceramic rotating shaft 1 with the metal rotating shaft 2, each end face 1b, 2b
is preferably perpendicular to the axial direction.

In the present invention, in such a structure, a heat insulating material 3 is provided at the abutting part between these end surfaces 1b and 2b.
It is something that has been interposed.

It is desirable that the insulation material be made of a material that is durable even under high temperatures, so paper made of ceramic fibers such as alumina-silica and alumina,
Boards, cloth, etc. are suitable. Insulating materials made of inorganic fibers such as asbestos fibers, rock wool, and glass fibers are also effective.

Note that even if the thickness of the insulation layer is thin, it will still have some effect, but considering its role as a buffer layer, it is usually
The thickness is preferably about 10 mm or more, but if it is too thick, there is a risk of axial play increasing due to the insulation material being crushed during use, so it is best to keep it at about 10 mm, and generally 0.2 kcal/m・hr・℃(at20℃)
It is best to use a heat insulating layer with a thermal conductivity of about the following.

Further, although it is necessary to interpose the heat insulating layer on the abutting surfaces as described above, it is also effective to appropriately interpose the heat insulating layer between the inner and outer circumferential surfaces of the shaft where the two fit together.

In this way, by interposing a heat insulating material in this part, it is possible to reduce the heat conduction from the water-cooled metal rotating shaft and prevent a drop in the temperature of the ceramic rotating shaft. possible. This is even more important considering that ceramic materials that can be used in making rollers are ceramics such as SiC, which have high thermal conductivity and are advantageous in terms of strength characteristics, etc., as mentioned above. That's true.

In addition, the presence of a heat insulating material can suppress the large tensile stress that is applied to the cooling surface and side surfaces when a sharp temperature distribution occurs in the axial direction at the end of the ceramic roller. It is also effective as a buffer layer.

Next, referring to FIGS. 2 to 15, a description will be given of the preferred fitting state of the ceramic rotating shaft portion and the metal rotating shaft portion of the present invention.

In order to explain the drawings, a cross section cut along the radial direction of the rotating shaft, that is, a direction perpendicular to the axial direction of the rotating shaft is defined as a cross section, and a cross section cut along the axial direction of the rotating shaft is defined as a longitudinal section. explain.

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FIGS. 2 and 3 show the simplest fitting state of circular cross sections.

FIG. 4 and FIG. 5 are vertical sectional views showing a convex portion 5 (concave portion 6) or a convex strip 7 partially on a part of the shaft portion.
(concave groove 8) is formed therein, and is fitted by shrink fitting or the like.

FIGS. 6 and 7 show that the protrusions 7 (grooves 8) are formed in a partial cross-sectional view, but are continuous in the vertical cross-sectional view.

Figures 8 to 11 show cross-sectional views of protrusions or grooves formed by being offset from the center, and in each example, a part of the ceramic rotating shaft is removed. Then, it is fitted and connected with a metal shaft part corresponding to this.

As illustrated in FIGS. 5 to 11, by making the cross-sectional shape of at least the fitting connection portion of both rotating shafts non-circular, there is no risk of idle rotation even if a clearance is created between the two shafts. From this point of view, there is no need for an elastic layer to be interposed between them, including the above-mentioned heat insulating material.

In addition, as shown in Figures 4 to 7, 10, and 11, stress concentration can be avoided by making the cross section of the ceramic rotating shaft smooth and avoiding corners. Can be done.

Furthermore, what is shown in FIGS. 10 and 11 is
The ceramic rotating shaft is made up of three approximately semicircular shapes that are cut out or protruded at an angle of approximately 120 degrees when viewed from the cross section. With this cross-sectional shape, the driving force can be distributed and received. This is more advantageous in terms of preventing destruction of ceramics due to stress concentration.

Next, the 12th section will discuss the structure seen from a more desirable vertical cross-sectional view of a fitting connection made of both materials.
This will be explained with reference to the figures and FIG.

Figure 12 shows a tapered surface 9 on a part of the mating part.
, and FIG. 13 shows the fittings in such a way that a tapered surface 9 is formed on almost the entire fitting portion.

By doing this, even if the outer rotating shaft made of metal expands and the clearance between it and the inner ceramic shaft increases when viewed from a cross section, causing wobbling, both ends of the rotating shaft will remain fixed. Or, as long as it is fixed via a spring or the like, it will also expand in the axial direction, so that expansion will act in a direction that cancels out this expansion, and as a result, excessive tensile stress will not be applied to the ceramics, and This makes it possible to create a connection structure that is less prone to wobbling.

14 and 15 show examples of the abutting portion formed by the end surface 1b of the ceramic rotating shaft and the end surface 2b of the metal rotating shaft.
The figure shows one formed on an inclined surface.

As for the connection structure in the present invention, it is also possible to simultaneously design preferable structures from both the cross-sectional and longitudinal cross-sections, and although such a structure is somewhat complicated, it can be used depending on the application. can be very effective.

In FIG. 1, the metal rotating shafts 2, 2 are generally connected to a drive device (not shown) for rotation.

As described above, the present invention makes it possible to provide a ceramic roller that can be used under high-temperature conditions and has great durability by preventing destruction of ceramics, and has extremely high practical value.

Example A silicon carbide sintered body with a diameter of 6 cm and a height of 1 m (contains 5 wt% of Al ₂ O ₃ as a sintering aid, and has a bulk density of
99% theoretical density) was cut out at three locations, each extending 8 cm from both ends, as shown in Figure 10. In Fig. 10, the depth of cut was 7 mm and the width of cut was 10 mm.

Next, attach a steel fitting with an inner diameter of 6 cm and a depth of 9 cm to a steel fitting with a diameter of 9 cm.
A 7.5 cm hole was drilled, and three protrusions that fit into the recesses 1 in Figure 10 were welded to the inner circumferential surface of the hole, and 5 mm thick ceramic paper was placed on the abutting surface to fit them.

The rollers obtained as described above were installed on the hearth of a steel heating furnace at intervals of 80 cm. A stack of 100 kg of steel material was transferred on this roller at a speed of 5 m/min and heated to 1200°C. During the approximately 4-month test period
200 tons of steel were transferred. The results showed that there was no damage to the ceramic roller or its connections, while the reduction was approximately 20% compared to a conventional water-cooled metal roller.
This made it possible to reduce fuel consumption, and the expected energy-saving effect was fully recognized.

[Brief explanation of the drawing]

Figure 1 is a sectional view explaining a typical example of the connection of the present invention, and Figures 2 to 15 are some of the fitting connections.
FIG. 2 is a cross-sectional view for explaining a
It is an AA cross-sectional view of. In the drawing, 1 is a rotating shaft made of ceramics,
2 is a rotating shaft made of metal, 3 is a heat insulating material, 5 is a convex portion, 6 is a concave portion, 7 is a convex strip, 8 is a concave groove, and 9 is a tapered surface. 〓〓〓〓

Claims (1)

[Claims for Utility Model Registration] 1. Fittingly connected with the rotating shaft made of ceramics on the inside and the rotating shaft made of metal on the outside,
A ceramic roller in which both rotating shaft parts are formed with abutting parts in the axial direction, and a heat insulating layer is interposed between the abutting parts. 2. A ceramic roller according to claim 1, which is fitted so that the cross-sectional shape of the fittingly connected portions cut along the radial direction of the rotating shaft forms a non-circular portion. 3. Utility model registration claims 1 or 2 in which the cross-sectional shape of the part where the two are fitted and connected is cut along the axial direction of the rotating shaft and is fitted so as to form a tapered surface. Ceramic roller as described.