JP2000344321A - Ceramic conveyor belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat resistance, oxidation resistance and corrosion resistance, reduce a thermal expansion coefficient and use a conveyor belt under high temperature by forming at least one of a link body, a link plate and a bar pin as conveyor belt components, out of a boron carbide sintered body. SOLUTION: A conveyor belt 1 is formed by mutually connecting a link body 2 and a link plate 3 by a bar pin 4. The bar pin 4 is integrally provided with a stopper 4a as a large diameter part on its one end, and stopped by locking a U-shaped fixed pin to an annular groove formed on the other end. On this occasion, at least one of the link body 2, the link plate 3 and the bar pin 4, and more preferably the U-shaped fixed pin are made out of a boron carbide sintered body. The boron carbide sintered body is mainly composed of boron carbide, and preferably contains 0.05-5 wt.% of a silicon compound and 0.5-5 wt.% of an organic compound capable of changing to carbon by thermal decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyor belt made of a ceramic material.

[0002]

2. Description of the Related Art Many conventional conveyors are mainly made of metal materials such as steel. Further, a rubber material having flexibility or a ceramic belt adhered to a rubber belt for imparting abrasion resistance has been used.

However, steel belts are subject to rust and wear easily, and when they are exposed to corrosive gas atmospheres or acids or alkalis, chemical wear is added to mechanical wear, which doubles the wear or causes brittle fracture. There was a risk of cutting. In addition, when used in a high-temperature atmosphere, in addition to oxidizing the metal and greatly reducing the strength, the thermal expansion causes the entire belt to expand, which not only hinders transmission of driving force or synchronous operation, but also This causes inconvenience in meshing with the gear used in combination with the belt, resulting in uneven wear of the gear. Further, those using steel have many inconveniences due to being conductive as well as being magnetic. Similarly, belts made of stainless steel are relatively excellent in terms of rust generation and corrosion resistance, but have a large amount of wear, poor durability, and acid,
It has the disadvantage that it is still weak to alkalis, and its thermal expansion is large, so that the amount of elongation at high temperatures becomes quite large, especially when the overall length is long, and there is a problem that cannot be ignored in use.

On the other hand, rubber belts have elasticity, flexibility,
Although it has features such as electrical insulation, it is elongated with use, has a large amount of abrasion, and is completely unsuitable especially when carrying an atmosphere having a high temperature or a high-temperature object.

[0005] Therefore, an attempt has been made to form a link member 2, a link plate 3, and a bar pin 4 as a conveyor belt structure from a ceramic material for a conveyor belt 1 as shown in FIG. (See Japanese Patent Publication No. 7-61802.) The conveyor belt 1 is formed by connecting a link body 2 and a link plate 3 which are conveyor belt structures with bar pins 4. In this case, a stopper 4a integrally formed with a large diameter portion is formed in the bar pin 4, and an annular groove 4b is formed in the other end of the bar pin 4. Therefore, after connecting by inserting the bar pin 4 into the through holes formed in the link body 2 and the link plate 3, respectively,
As shown in FIG. 2A, the U-shaped fixing pins 5 are engaged by being locked, and the link body 2 and the link plate 3 are rotatably supported by the bar pins 4.

[0006]

In the above-mentioned ceramic conveyor belt, ceramics mainly composed of alumina, zirconia, silicon carbide, silicon nitride and the like are used as constituent members. Although excellent effects were obtained, sufficient wear resistance was not obtained for long-term use.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and at least one of a link body, a link plate, and a bar pin, which are a conveyor belt structure, is formed of a boron carbide sintered body. It is characterized by.

Further, the present invention provides the above-mentioned boron carbide-based sintered body containing boron carbide as a main component and a silicon compound in an amount of 0.0
It is characterized by using a sintered body containing 5 to 5% by weight of an organic compound which can be converted into carbon by thermal decomposition at a rate of 0.5 to 5% by weight in terms of carbon.

Further, the present invention is characterized in that a boron carbide-based sintered body having a Vickers hardness of 20 GPa or more and a Young's modulus of 430 GPa or more is used.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a conveyor belt. The conveyor belt 1 is formed by connecting a link body 2 and a link plate 3 which are a conveyor belt structure with bar pins 4. A stopper 4a integrally formed with a large diameter portion is formed on the bar pin 4, and an annular groove 4b is formed in the other end of the bar pin 4. Therefore, after connecting by inserting the bar pin 4 into the through holes formed in each of the link body 2 and the link plate 3, the U-shaped fixing pin 5 as shown in FIG. As shown in FIG. 1A, the link body 2 and the link plate 3 are rotatably supported by the bar pins 4.

Since the protruding portion 5a is integrally provided inside the tip of the U-shaped fixing pin 5, it differs depending on the overall length and width of the U-shaped fixing pin 5 and the type of the ceramic material. , But a very slight flexing and spreading occurs. Therefore, the U-shaped fixing pin 5 is inserted and engaged in the annular groove 4b formed in the bar pin 4 by utilizing this bending, and then stably stops in a state where the protrusion 5a includes the annular groove 4b.
Since the U-shaped fixing pin 5 exists in the annular groove 4b of the bar bin 4, the structure of the belt conveyor 1 is maintained without disassembly of the link body 2, the link plate 3, and the bar pin 4.

In order to function as the U-shaped fixing pin 5, it is necessary to make it as easy to spread as possible. In order to be able to be inserted into the annular groove 4b, the bending amount is shown in FIG.
In the case of two legs as described above, a minimum of about 0.2 mm is required.

In the present invention, at least one of the link body 2, the link plate 3, and the bar pin 4, and more preferably, the U-shaped fixing pin 5 is formed of a boron carbide sintered body. The boron carbide-based ceramic contains boron carbide as a main component, a silicon compound in an amount of 0.05 to 5% by weight, and an organic compound which can be converted to carbon by thermal decomposition at a rate of 0.5 to 5% by weight in terms of carbon. It is made of a sintered body.

The amount of the silicon compound contained here is 0.0
It is 5 to 5% by weight, preferably 0.1 to 2% by weight, more preferably 0.2 to 1% by weight. This amount is 0.05
If it is less than 5% by weight, densification is difficult, and if it exceeds 5% by weight, boron carbide causes grain growth and lowers the strength.

Similarly, the carbon content is 0.5 to 5% by weight, preferably 1 to 4% by weight. If it is less than 0.5% by weight, densification is difficult, and if it exceeds 5% by weight, on the contrary, the growth of boron carbide particles is suppressed and the densification is hindered.

Further, the boron carbide based sintered body is characterized by having a Vickers hardness of 20 GPa or more and a Young's modulus of 430 GPa or more.
By being formed of a sintered body having a Young's modulus, dimensional stability and abrasion resistance of the conveyor belt are increased.

Here, if the Vickers hardness is less than 20 GPa, the abrasion becomes so severe that it cannot be used. Also, when the Young's modulus is less than 430 GPa, the rigidity is reduced, the material is easily deformed, and the one-sided contact is caused. As a result, local wear is promoted and the life is shortened.

Further, since the boron carbide sintered body is non-magnetic, has excellent corrosion resistance and heat resistance, and has a coefficient of thermal expansion that is extremely small as compared with the metal ratio, it can be used at high temperatures, acids, alkaline liquids, corrosive gases, etc. It is possible to sufficiently withstand use in places exposed to water, and to maintain durability and high accuracy.

Next, a method of manufacturing the link body 2, link plate 3, bar pin 4, and U-shaped fixing pin 5, which are belt conveyor components, using the boron carbide sintered body of the present invention will be described.

For example, 0.05 to 5% by weight of a boron carbide powder having an average particle diameter of 5 μm or less and a silicon carbide powder having an average particle diameter of 1 μm or less and / or an organosilicon compound which can be converted to silicon carbide by thermal decomposition, An organic carbon compound which can be converted to carbon by thermal decomposition is mixed at a ratio of 0.5 to 5% by weight in terms of carbon. Hereinafter, the silicon carbide powder and the organosilicon compound are also collectively referred to as a silicon carbide source.

As the organosilicon compound, polycarbosilane, polysilastyrene, polysilazane, polycarbosilazane and the like can be preferably used. Examples of the organic compound that can be converted to carbon include coal tar pitch, furfuryl alcohol, corn starch, sugars, and phenol resins.

In this case, the average particle size of the boron carbide powder is 5
μm or less, preferably 2 μm or less, more preferably 1 μm
m or less. When the average particle size exceeds 5 μm, insufficient densification is caused to cause a decrease in strength.

Next, the mixture is formed into a predetermined shape by, for example, a die press, a cold isostatic press, injection molding, extrusion molding, or the like. After molding into a predetermined shape, 1
At a temperature of 600 to 2100 ° C., a purification treatment is performed in a vacuum of 5 Pa or less so that each of the alkali metal, the alkaline earth metal and the transition metal becomes 100 ppm or less.
It is baked at a temperature of 50 ° C. or less to densify it to a relative density of 96% or more.

The firing temperature is preferably 1900-2.
The temperature is 100 ° C. and firing is performed in an argon gas. If the firing temperature exceeds 2250 ° C., boron carbide grains grow and cause a decrease in strength.

The obtained boron carbide sintered body is subjected to polishing and the like, and then assembled as a conveyor belt.

The method of manufacturing the U-shaped fixing pin 5 is as follows.
There are various methods such as a powder pressing method in which a ceramic raw material powder is filled in a pin-shaped mold and molding, a casting method, and a method of obtaining a shaped body of the U-shaped fixing pin 5 by a rubber pressing method.

In the present invention, at least one of the components of the conveyor belt may be formed of the above-mentioned boron carbide-based sintered body. is there.

In the above-described embodiment, the bar pin 4 is shown as one in which the stopper 4a is integrally formed at one end. However, the present invention is not limited to this, and the U-shaped fixing pin 5 is inserted and locked at the other end. The groove 4b may be engraved.
The U-shaped fixing pin 5 having a high rigidity and a small bending amount is inserted into the annular groove 4b formed in the bar pin 4, and therefore, it is required that the depth of the groove be high.
Alternatively, one end or both ends of the bar pin 4 can be locked by means different from the U-shaped fixing pin 5.

As described above, when the conveyor belt 1 constituted by the link body 2, the link plate 3, the bar pins 4, and the U-shaped fixing pins 5 is broken with use, the U-shaped fixing pins are used. 5 can be disassembled by pulling it out or breaking it down, and it is possible to easily replace and repair only broken parts such as the link body 2, the link plate 3, and the bar pins 4 with new parts.

[0031]

Embodiments of the present invention will be described below.

EXPERIMENTAL EXAMPLE 1 As boron carbide powder, the contents of Na, Ca, and Fe were 840 ppm, 120 ppm, and 300 ppm, respectively.
One having an average particle size of 0.8 μm (A-1: HS, manufactured by Stark Vitec Co., Ltd.) was used.

As silicon carbide powder, an average particle size of 0.6 μm
m (B-1: trade name 0Y-1 manufactured by Yakushima Electric Works Co., Ltd.)
5) and those that change to silicon carbide by high-temperature pyrolysis (B-
2: Nippon Carbon Co., Ltd. product name Polycarbosila NIP
US1-S) was used. In addition, B-2 was used after being dissolved in an organic solvent.

As a carbon source, a phenol resin having a carbonization ratio of 40% (C-1: manufactured by Sumitomo Teles Co., Ltd.) was used. This C-1 was also used after being dissolved in an organic solvent.

As comparative examples, boron carbide powder having a crystal grain size of 20 μm (A-2: product name F3 of Denki Kagaku Kogyo Co., Ltd.) and silicon carbide powder having an average particle size of 5 μm (B-3: (Shown by Showa Denko KK) and carbon powder with a crystal grain size of 400 mm (C-2: Denki Kagaku Kogyo Co., Ltd.)
(Acetylene Black, Denka Black).

Then, the above-mentioned boron carbide powder, silicon carbide source, and carbon source are weighed in combinations and amounts shown in Table 2 below, and mixed in an organic solvent using a plastic ball.
A dry powder was obtained using an evaporator. In Table 1, wt% means weight%, and those with sample numbers marked with * are out of the scope of the present invention (comparative examples).

The firing was performed using a hot press (HP) firing apparatus. A powder composed of a boron carbide powder, a silicon carbide source, and a carbon source was placed in a carbon mold and heated at a temperature shown in Table 1.
Purification treatment was carried out for a period of time, and thereafter, the mixture was held at a firing temperature shown in Table 1 under a pressure of 30 MPa (megapascal) for 2 hours, and fired.

A test piece was cut out from the obtained sintered body and polished. Then, the specific gravity was determined (based on JISR2205), and the relative density was determined. The strength of the sintered body (flexural strength) was determined at room temperature from a four-point bending test (JIS).
R1601). Also, two samples were crushed, and I
CP emission spectroscopy (Inductive CoupledP
lasma Atomic Emission Spe
The amount of Na, Ca, and Fe was measured by an analysis method (ctroscopy).

According to Table 1, Sample No. 1 containing no silicon carbide or carbon was used. Nos. 1 to 4 had low density and low strength. Sample NO. 5 containing more than 5% by weight of silicon carbide. 1
Sample No. 2 whose strength was reduced and whose carbon content exceeded 10% by weight. In No. 18, the density decreased and the strength also decreased.

Sample NO. 1 using boron carbide powder (A-2) having an average particle size exceeding 5 μm. 23 is a silicon carbide (B-3) whose strength is reduced and whose average particle size exceeds 1 μm;
Sample No. using powdery carbon (C-2). 25, N
O. Sample No. 28 had a reduced density and a reduced strength.

Further, the sample No. having a purifying temperature lower than 1600 ° C. 19 has a large amount of impurities and a purification temperature of 21
Sample NO. In No. 22, the density decreased and the strength also decreased.

On the other hand, using boron carbide powder (A-1) having an average particle size of 5 μm or less, silicon carbide (B-1) having an average particle size of 1 μm or less and / or an organic compound which can be converted to silicon carbide by thermal decomposition. 0.05 to 5% by weight of the silicon compound (B-2) is an organic compound (C-
1) was mixed at a ratio of 0.5 to 5% by weight in terms of carbon, and the mixture was formed into a predetermined shape.
The samples of the present invention, which were purified in a vacuum at a temperature of 0 ° C. and then fired at a temperature of 2250 ° C. or less, had a relative density of 96% or more, a four-point bending strength of 200 MPa or more, and a high strength. , Alkaline earth metal and transition metal element were each 100 ppm or less and high purity.

[0043]

[Table 1]

Experimental Example 2 Next, various components having the characteristics shown in Table 2 were used for all the constituent members of the ceramic conveyor belt 1 of the present invention shown in FIG. An experiment was conducted to examine the amount of wear with respect to Vickers hardness and Young's modulus. The conditions of use of this actual machine are conveyor belt 1
Apply constant tension to the belt with no load
Per second. The amount of elongation with respect to a sprocket span of 50 mm in length was applied as a measure of the amount of wear. Table 3 shows the results after the test.

From the results shown in Table 3, it can be seen that, in the case of silicon carbide and alumina of the comparative examples, the conveyor belt 1
Elongation exceeds 0.6 mm and wear is severe, whereas in the boron carbide sintered bodies of Samples 8 and 17 of the present invention, the
Conveyor belt 1 stretches 0.6m even if it exceeds 200H
m or less, and the performance can be sufficiently protected.

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

As described above, according to the present invention, at least one of the link member, the link plate, and the bar pin, which are the components of the conveyor belt, contains boron carbide as a main component and a silicon compound of 0.05 to 5%. By using a boron carbide sintered body containing 0.5 to 5% by weight of an organic compound which can be converted to carbon by thermal decomposition in a ratio of 0.5 to 5% by weight in terms of carbon, it has heat resistance and oxidation resistance. Because of its low coefficient of thermal expansion, it can be used in high-temperature areas, and because of its high corrosion resistance, it can be used in marine development and chemical plant-related applications. It is also non-magnetic and electrically insulating. For this reason, the present invention is extremely useful as a configuration of a magnetic storage device that loses magnetism, a rotary drive component related to an electronic device, and a transport device.

Further, since the boron carbide-based sintered body has a Vickers hardness of 20 GPa or more and a Young's modulus of 430 GPa or more, it has great wear resistance, so that the desired accuracy can be obtained for a long period of time. This is useful for constructing a drive system.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a ceramic conveyor belt of the present invention.

FIG. 2A is a sectional view taken along line YY in FIG. 1;
(B) is a perspective view of only the U-shaped fixing pin.

[Explanation of symbols]

 1: Conveyor belt 2: Link body 3: Link plate 4: Bar pin 4a: Stopper 4b: Annular groove 5: U-shaped fixing pin 5a: Projection

Claims (3)

[Claims] 1. A conveyor belt in which a bar pin is inserted through and connected to each through hole formed in a link body and a link plate, wherein at least one of the link body, the link plate and the bar pin is made of a boron carbide sintered body. A ceramic conveyor belt formed of: 2. The boron carbide-based sintered body contains boron carbide as a main component, a silicon compound in an amount of 0.05 to 5% by weight, and an organic compound which can be converted to carbon by thermal decomposition in an amount of 0.5 to 5% in terms of carbon. The ceramic conveyor belt according to claim 1, wherein the content is 5% by weight. 3. The ceramic conveyor belt according to claim 1, wherein the boron carbide-based sintered body has a Vickers hardness of 20 GPa or more and a Young's modulus of 430 GPa or more.