JP2003035090A - Cutter bit for excavation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutter bit for excavation, which is excellent in abrasion resistance, impact resistance and corrosion resistance, and capable of continuously carrying out long-distance excavation. SOLUTION: The cutter bit for the excavation is used for an underground excavator such as a shield machine; a cutter bit body is formed of carbon steel, chromium/molybdenum steel, etc.; and a spray deposit layer is formed by thermally spraying an outer surface of the cutter bit body with powder for thermal spraying, in which cermet powder is mixed with a metal powder containing nickel or nickel and chromium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an excavating cutter bit used for an underground excavator such as a shield excavator,
In particular, the present invention relates to a cutter bit for excavation, which has improved wear resistance, impact resistance and corrosion resistance of the cutter bit and is capable of continuously performing long-distance excavation.

[0002]

2. Description of the Related Art Conventionally, in a ground excavator such as a shield machine, a TBM (tunnel boring machine) and a road header, improvement in wear resistance of a cutter bit has been desired. In particular, with the recent tendency of long-distance excavation, the demand for it is extremely high.

When performing long-distance excavation with a conventional underground excavator equipped with a cutter bit, the cutter bit does not have the end and needs to be replaced in the middle. In that case, a shaft was built from the ground to form a work area in front of the excavator, and the cutter bit was replaced within the work area.

However, there is a problem that enormous cost and a long construction period are required for the construction work of the vertical shaft and the ground improvement around the work area.

Therefore, various devices have been proposed so that the cutter bits can be replaced without constructing a vertical shaft.
For example, rotate the cutter bit to expose it to the inside of the excavator, replace the cutter bit inside the frame of the excavator, or pull the cutter bit inside the frame to keep the ground side still. There is a device for exchanging the cutter bit in the frame.

[0006]

However, there is a problem that all the devices are complicated and the cost is significantly increased. In addition, the excavation work must be stopped during the replacement of the cutter bit, which causes a problem that the construction period is prolonged,
There were also problems such as the safety of cutter bit replacement workers.

Further, in an excavator for excavating a small-diameter tunnel such as a tunnel for cable wiring, it is impossible to carry out the exchanging work within the frame, and therefore a vertical shaft must be built.

Further, the cutter bit is generally constituted by a cutter bit body 50 made of carbon steel or the like and a tip 51 made of cemented carbide or the like brazed thereto, as shown in FIG. Due to impact or the like, the tip 51 may be chipped, dropped from the cutter bit body 50, or the cutter bit body 50 may be unevenly worn.

From the above, there has been a demand for a cutter bit for excavation which has excellent wear resistance, impact resistance and corrosion resistance and which can continuously perform long-distance excavation.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a cutting bit for excavation which is excellent in wear resistance, impact resistance and corrosion resistance and which can continuously perform long distance excavation. .

[0011]

In order to achieve the above object, the present invention relates to an excavating cutter bit used in an underground excavator such as a shield excavator, which is made of carbon steel, chrome molybdenum steel or the like. And the cermet powder and Ni or N are formed on the outer surface of the cutter bit body.
This is a sprayed coating layer formed by spraying a spraying powder in which i and a metal powder containing Cr are mixed.

According to this structure, it is not necessary to attach the chip to the cutter bit body by forming the spray coating layer having high hardness on the cutter bit body. Therefore, it is possible to excavate for a long distance without causing defects such as chipping and chipping. Further, since the thermal spray coating layer significantly improves the wear resistance, impact resistance and corrosion resistance of the cutter bit body, long-distance excavation can be continuously performed. Furthermore, the thermal spray coating layer can prevent uneven wear of the cutter bit body.

Further, a tip made of cemented carbide or the like may be attached to the cutter bit body, and the sprayed coating layer may be formed on the outer surface of the cutter bit body and the tip.

According to this structure, since the thermal spray coating layer formed on the attachment portion between the cutter bit body and the tip absorbs the impact applied to the tip, dropping of the tip is suppressed.

Further, the thermal spray coating layer may be formed on the outer surface of the tip made of cemented carbide or the like and attached to the cutter bit body.

According to this structure, the thermal spray coating layer greatly improves the wear resistance, impact resistance and corrosion resistance of the tip, and therefore long-distance excavation can be continuously performed.

The thermal spraying powder is a cermet powder containing tungsten carbide, chromium carbide and Ni, or tungsten carbide, Co and Cr as main components, and the total of Cr and Ni is 90 with respect to the total weight of the metal powder. %, And the content of Cr is 0 to 55% based on the total weight of the metal powder,
80 to 97%, 3 to 2% of the total weight of the thermal spray powder
It is added and mixed so that the content becomes 0%.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

This embodiment is applied to a cutter bit of a shield machine as an example of the present invention, and FIG.
It shows a cutter bit for excavation generally called a teeth bit.

The excavating cutter bit 10 is attached by a bolt or the like to a base portion 11 formed on a face plate rotatably provided at the tip of a shield machine, which is not shown, and the face plate rotates to allow the front ground to move forward. The mountain 12 is excavated.

The excavating cutter bit 10 has a front side (see FIG. 1).
The cutter bit main body 15 having the excavation portion 13 formed at an acute angle is provided in the middle upper side). This cutter bit body 1
5 is carbon tool steel such as S25C, S45C and SCM4
It is made of chrome / molybdenum steel such as 40 or alloy tool steel such as SKC24. However, the present invention is not limited to the material of the cutter bit body 15, and is not limited to the above.

Unlike the conventional cutter bit shown in FIG. 7, the cutter bit 10 of the present embodiment does not have a tip, and the outer surface of the cutter bit body 15 is sprayed with the powder for thermal spray, which is a feature of the present invention. By doing so, the thermal spray coating layer 16 is formed.

The thermal spray coating layer 16 may also be formed on the outer surface of the base 11.

The thermal spray coating layer 16 allows the excavating cutter bit 10 to have a hardness sufficient to excavate the natural ground 12 without attaching a tip. The thermal spray coating layer 16 allows the excavating cutter bit 10 to
Wear resistance, impact resistance and corrosion resistance are remarkably improved, and long-distance excavation can be continuously performed.

The thermal spraying powder for forming the thermal spray coating layer 16 will be described.

Generally, in the same meaning as "spraying",
The terms "meat fill" and "spray" are sometimes used. There is no clear definitional difference between these words, and the powders used therefor are not used separately, and even powders for forming a thermal spray coating are not limited to those for thermal spraying. That is, powder for thermal spraying is used for padding or spraying, and conversely, powder for padding or spraying is used for thermal spraying. Therefore, it goes without saying that the “spraying powder” in the present specification is also used for applications such as “buildup” and “spray”.

The thermal spraying powder used in the present embodiment is formed by mixing cermet powder and Ni or a metal powder containing Ni and Cr. Specifically, tungsten carbide, chrome carbide and Ni, or cermet powder containing tungsten carbide, Co and Cr as main components, and the total of Cr and Ni occupy 90% or more with respect to the weight of the entire metal powder, and , The content of Cr is 0 to 55% with respect to the total weight of the metal powder, and 80 to 97% with respect to the total weight of the thermal spraying powder.
It is added and mixed so that the content is up to 20%.

Here, the cermets are Ceramics and Metal.
It is a coined word in which the first three letters of each of (metal) are joined together, and specifically, it is a composite material in which hard ceramic particles are bonded by a metal matrix and which has high hardness and high toughness. In the field of tool materials, cermet refers to TiC-based and Ti (C, N) -based materials,
In a broad sense, it includes all composite materials of ceramics and metals.

The cermet powder used in this embodiment contains WC (tungsten carbide), CrC (chromium carbide) and Ni (nickel), or tungsten carbide, Co (cobalt) and Cr (chromium) as main components.

Among these, in the cermet powder mainly composed of tungsten carbide, chromium carbide and Ni, tungsten carbide plays a role of improving wear resistance, and Ni serves as a binder, as well as toughness and corrosion resistance. Is to improve. And chrome carbide further improves the corrosion resistance of tungsten carbide and Ni. Especially, the cutting bit for excavation is often used in a wet environment,
From the viewpoint of improving wear resistance and corrosion resistance in a wet environment, the contents of tungsten carbide, chromium carbide and Ni with respect to the total weight of the cermet powder are 60 to 85%, 10 to 30% and 4 to 15 respectively.
%, More preferably 65 to 80% and 15 respectively
-25%, and 5-12%.

Among the cermet powders containing tungsten carbide, Co and Cr as the main components, the cermet powder containing tungsten carbide and Co has excellent toughness, wear resistance and impact resistance.
It is a widely known powder for thermal spraying. And Cr
Is to improve the corrosion resistance of the cermet made of tungsten carbide and Co. By containing Cr, it has corrosion resistance comparable to the cermet containing tungsten carbide, chromium carbide and Ni as the main components, and shows a great advantage over other cermets.
In particular, since the cutting bit for excavation is often used in a wet environment, from the viewpoint of improving impact resistance and corrosion resistance and wear resistance in a wet environment, tungsten carbide, C
The contents of o and Cr are 80 to 92% and 4 to 20%, respectively.
%, And 2 to 15% are preferable, and more preferably 84 to 90%, 6 to 12%, and 2 to 10%, respectively.

For tungsten carbide, WC, W2
There is C, but it is preferable to use WC. This is because when W2C is used, W is generated by a decarburization reaction when exposed to high temperatures such as in a sintering process or during thermal spraying, which may deteriorate the properties of the thermal spray coating layer. If WC is used, the decarburization reaction as described above is less likely to occur, and even if this reaction occurs, the generation of W and the change in the properties of the thermal spray coating layer can be suppressed.

Similarly, for chromium carbide, Cr3C is used.
There are 2, Cr7C3 and Cr23C6, but chromium carbide is converted from Cr3C2 to Cr7C3 by C
It is said that the crystal phase changes from r7C3 to Cr23C6 and from Cr23C6 to Cr, and it is preferable to use Cr3C2 or Cr7C3 because it is necessary to suppress a large change in the properties of the thermal spray coating layer.
Is more preferably used.

If the average particle size of the tungsten carbide and chromium carbide constituting the cermet powder is too small, the thermal spray coating layer has a large external force (impact).
When it is exposed, cracks are likely to occur and the impact resistance tends to be low. On the other hand, if the average particle size of tungsten carbide or chromium carbide is too large, it becomes difficult to obtain granules in which the raw material components are uniformly dispersed in the granulation step, spherical granules are prepared, and the granules are prepared using the granules. When thermal spraying is performed using the thermal spraying powder, the thermal spraying efficiency becomes very low. Therefore, the average particle size of tungsten carbide is generally 2 to 20 μm, preferably 5 to 12 μm, and the average particle size of chromium carbide is generally 1 to 1 μm.
It is 0 μm, preferably 3 to 7 μm.

Further, when tungsten carbide or chromium carbide used for the cermet powder and containing free carbon is used, the bond strength inside the thermal spray coating may be lowered and the impact resistance may be significantly lowered. Therefore,
The content of free carbon in the tungsten carbide and the chromium carbide used in the cermet powder is preferably 0.05% by weight or less and 0.1% by weight or less, respectively.

On the other hand, Ni and C constituting the cermet powder
Metal powders such as o and Cr are preferably finely powdered uniformly, and in the granulation step, the smaller the average particle diameter of the metal powder used, the more spherical the cermet powder with high mechanical strength is produced. Therefore, it becomes easy to produce a powder having a desired particle size distribution, and the product yield increases. Therefore, the average particle size of these metal powders is generally 5 μm or less, preferably 3 μm or less. When using the alloy powder produced by the atomization method, the average particle size is generally 10 μm, and preferably 5 μm or less.

Next, the metal powder mixed with such cermet powder is adjusted to have the same particle size distribution as the cermet powder obtained by the granulation-sintering method, the sintering-grinding method, or the melt-grinding method. It is preferable to use the one.
As such a metal powder, a metal powder having a high sphericity prepared by an atomizing method is typical. The atomizing method includes a water atomizing method and a gas atomizing method.The amount of dissolved oxygen in the metal powder and the powder shape are slightly different depending on the difference, but the effect on the characteristics of the sprayed coating layer is small, and the metal powder by the atomizing method is used. Any of them can be used.

As the content of Cr contained in the metal powder mixed with the cermet powder used in the present embodiment is increased, the wear resistance and corrosion resistance of the thermal spray coating layer are improved, but the impact resistance is improved. On the contrary, the smaller the content, the higher the impact resistance of the thermal spray coating layer, but the wear resistance and corrosion resistance tend to decrease. For example, the content of Cr in the metal powder is 55 with respect to the total weight of the metal powder.
%, The impact resistance of the thermal spray coating layer will be greatly reduced and the coating will be prone to cracking. Therefore, in the present embodiment, the content of Cr in the metal powder is generally 0 to 55%, preferably 5 to 30% based on the weight of the entire metal powder.

Further, in the step of preparing the metal powder to be mixed with the cermet powder, C in the metal powder may be mixed as an impurity, finely divided during atomization, or added for other purposes. The metal ingot may also contain C, but if the content of C is too large with respect to the total weight of the metal powder, the impact resistance of the coating tends to be significantly reduced. Therefore, the content of C in the metal powder is generally 0.4% or less, preferably 0.2% or less, based on the total weight of the metal powder.

Further, the metal powder mixed with the cermet powder includes Si, B, Al, Mn, in addition to Ni and Cr.
Components represented by Ti, Fe, S, Mo, etc. may be mixed as impurities or added for atomization during atomization and for other purposes, and these components may be contained in the metal ingot. However, if the amount of these components is too much with respect to the total weight of the metal powder, the impact resistance of the thermal spray coating tends to be greatly reduced. Therefore, S in metal powder
The total content of i, B, Al, Mn, Ti, Fe, S, and Mo is generally 10% or less, preferably 3% or less, based on the total weight of the metal powder.

Such a thermal spraying powder is manufactured by the following means using each of the above components.

First, with respect to the total weight of the cermet powder,
60-80% tungsten carbide, 10-30%
Raw material powders are mixed so as to contain 5 to 15% of Ni, and WC / CrC / is formed by a general granulation-sintering method, a sintering-grinding method, or a melt-grinding method.
Prepare a Ni-based cermet.

In the granulation-sintering method among the methods for preparing cermet powder, the granules are granulated so as to have a particle size distribution of 5 to 75 μm and sintered at 900 ° C. or higher for 5 hours or longer. Is preferred. The sintering conditions need to be optimized depending on the composition of the thermal spraying powder and the required properties, but uniform and hard spherical particles can be obtained by sintering at a constant temperature for 5 hours or more. When using metal powder such as Ni, Co, Cr or their alloys, or carbide ceramics such as chromium carbide and / or tungsten carbide as the cermet raw material,
At the time of degreasing / sintering, it is necessary to prevent these raw materials from oxidizing, and they are generally processed in a vacuum or an inert gas atmosphere.

As an example, a cermet having a particle size distribution of 6 to 63 μm, which is suitable for high speed flame spraying, can be obtained by sintering, crushing and classifying granular powder having a particle size distribution of 5 to 75 μm. Further, if necessary, the particle size distribution 6 can be obtained by changing the granulation, crushing, or classification conditions.
~ 38 μm, 10-45 μm, 15-45 μm, 15-
Prepare 53 μm, 20-63 μm cermet powder,
It can be used properly according to the type of thermal spraying equipment and thermal spraying conditions.

In the present specification, the term "particle size distribution" means that the lower limit of the particle size distribution is smaller than the particle size described by using a laser diffraction particle size analyzer LA-300 (manufactured by Horiba Ltd.). The ratio of particles is 5% or less, and the upper limit of the particle size distribution is 5% or less than the particle size described by the value obtained by the Low-tap method (JIS R6002). For example, if the particle size distribution is 15 to 45 μm, the proportion of particles of 15 μm or less obtained using a laser diffraction particle size analyzer is 5% or less, and of particles of 45 μm or more obtained using the low tap method. It indicates that the ratio is 5% or less. On the other hand, "average particle size" means the same LA-300
The value of D50 obtained by using is shown.

The thermal spraying powder used in this embodiment is manufactured by separately mixing the cermet thus prepared with a metal powder.

The metal powder is based on the total weight of the metal powder.
Ni is mixed so that the content of Cr is 0 to 55% and the total content of Cr is 90% or more to prepare a metal powder.

Then, the cermet powder and the metal powder are uniformly mixed so that the content of the metal powder is 3 to 20%, preferably 7 to 16% based on the total weight of the thermal spray powder. Produce powder for use.

If the content of cermet in the thermal spraying powder exceeds 97% and the content of metal powder is less than 3%, the proportion of the metallic phase scattered in the thermal spray coating layer decreases, so the coating film The impact resistance of is low. Conversely, the content of cermet is less than 80%, the content of metal powder is 20%
If it exceeds the above range, the proportion of the ceramic component excellent in wear resistance and corrosion resistance decreases, so that the corrosion resistance and wear resistance of the thermal spray coating layer decrease.

The reason why the thermal spray coating layer formed by thermal spraying this thermal spraying powder has extremely high impact resistance, excellent abrasion resistance, and excellent corrosion resistance and abrasion resistance in a wet environment is as follows. Is speculated as.

Observing the structure of the thermal spray coating layer formed by thermal spraying the thermal spray powder of this embodiment, the metal powder components are laminated in a state of having an appropriate thickness and scattered as a relatively large metal phase. Is confirmed. When a large external force is applied to the thermal spray coating layer, it is presumed that this metal phase plays a role of a cushioning material and absorbs and disperses the external force, whereby the impact resistance of the thermal spray coating layer is greatly improved.

On the other hand, observing the structure of the thermal spray coating layer formed by thermal spraying the WC / Co cermet thermal spraying powder which is a conventional general thermal spraying cermet powder, the materials constituting the thermal spraying powder melted. Only a thin metal phase that is mixed with other materials is observed, and a relatively large metal phase laminated with a proper thickness as observed in the thermal spraying powder of the present embodiment is not confirmed. For this reason, when a large external force is applied to the thermal spray coating layer, there is no metal phase that can sufficiently play the role of a cushioning material, the external force is not absorbed and dispersed, and coating destruction occurs, and the impact resistance of the thermal spray coating layer is It is presumed that it will be lower than that of the present embodiment.

In addition, as in the above-described method for producing the thermal spraying powder in the present embodiment, the cermet powder and the metal powder are separately prepared, and these are mixed at an appropriate ratio. Of the cermet powder and the metal powder from the beginning are combined, and a thermal spray coating is obtained by performing thermal spraying using the thermal spraying powder produced by the granulation-sintering method, the sintering-grinding method, or the melt-grinding method. When the layer structure is observed, it is presumed that the metal powder component mixes with other materials in the film or only a thin metal phase is formed, so that it is not possible to obtain high impact resistance as in this embodiment. .

The thermal spraying powder of this embodiment is J manufactured by TAFA.
P-5000, UNIQUE COAT TECHNO
High speed flame spray represented by equipment such as LOGIES INTELLI-JET HVAF or equipment such as Sulzer Metco diamond jet, flame spray represented by equipment such as Sulzer Metco 6P, equipment such as Sulzer Metco 9MB, and PRAXAIR SG-100. It is applicable to known thermal spraying methods such as plasma spraying.

Flame spraying means that a spraying powder is sent into a combustion flame in which oxygen and a fuel (for example, acetylene) are burned.
It is a thermal spraying method in which powder is made to collide with a substrate in a molten or semi-molten state and laminated to form a coating layer. High-speed flame spraying is a type of flame spraying, but by increasing the pressure in the combustion chamber and increasing the velocity of the combustion flame very much, the spray particles are greatly accelerated and a strong collision force is generated, resulting in a close and close contact. This is a thermal spraying method capable of forming a coating having high strength. Plasma thermal spraying is a thermal spraying method in which a thermal spraying powder is heated by high-temperature plasma to melt the thermal spraying powder and spray it onto a substrate to form a coating.

The thermal spray coating layer obtained by using the thermal spray powder of the present embodiment is laminated with the metal powder component having an appropriate thickness, and is scattered as a relatively large metal phase in the coating. It is preferable, however, to form such a coating, the thermal spraying powder, particularly the metal powder component, is not heated too much,
It is necessary to stack the coating with a large acceleration and a large impact force on the substrate. High-speed flame spraying can greatly accelerate the sprayed particles compared to flame spraying or plasma spraying, and because the residence time in the combustion flame is short, the spraying powder is not exposed to high temperatures,
It is suitable for the powder for thermal spraying of this embodiment. Among high speed flame spraying, JP-5000 and INTELLI-JET
HVAF is particularly suitable because it can greatly accelerate the thermal spray powder and the thermal spray powder is not exposed to higher temperatures.

The thermal spraying powder of this embodiment as described above is thermally sprayed on the outer surface of the cutter bit body 15 made of carbon steel or the like to form the thermal spray coating layer 16 as shown in FIG. The bit body 15 can obtain sufficient hardness as a cutter bit for excavation. Therefore, unlike the conventional case, it is not necessary to separately attach a tip made of cemented carbide or the like to the main body of the cutter bit, and naturally, the problem of chipping or dropping of the tip during excavation does not occur, and long-distance excavation becomes possible. .

Further, as described above, by forming the thermal spray coating layer 16, the wear resistance, impact resistance and corrosion resistance of the excavating cutter bit 10 are significantly improved as compared with the conventional cutter bit. Therefore, it becomes possible to continuously excavate long distance without exchanging the cutter bit.

The present invention can also be applied to an excavating cutter bit of a type in which a tip is attached to the cutter bit body, and an application example thereof will be described with reference to FIGS. 2 and 3.

The chip 19 is, for example, JIS-M-391.
It is formed of E3 type, E5 type, etc. of "Cemented carbide tip for mining tools" defined in 6. The method of attaching the tip 19 to the cutter bit body 15 is shown in FIGS.
The plate type shown in (a) and FIGS. 2 (b) and 3
There is an insert type shown in (b). In both types, the tip 19 and the cutter bit body 15 are fixed by brazing.

The form shown in FIG. 2 is a cutter bit body 1
Attach the chip 19 to 5, and the cutter bit body 1
5 and the entire outer surface of the tip 19 is sprayed with the above-mentioned spray powder to form the spray coating layer 16. Even in this embodiment, the thermal spray coating layer 16 significantly improves the wear resistance, impact resistance and corrosion resistance of the cutter bit body 15 and the tip 19, so that long-distance excavation is performed without exchanging the cutter bit. be able to. Further, since the thermal spray coating layer 16 is also formed on the brazing portion 20 for attaching the chip 19 and the cutter bit body 15, the thermal spray coating layer 16 serves as a cushion and serves as the chip 19.
Can be prevented from dropping. Further, the sprayed coating layer 16 can prevent the chip 19 from being chipped.

In the embodiment shown in FIG. 3, the thermal spray coating layer 16 is formed substantially only on the outer surface of the tip 19 for excavating the natural ground. Also in this form, the chip 1
Since abrasion resistance, impact resistance and corrosion resistance of No. 9 are greatly improved, long-distance excavation can be performed without exchanging the cutter bit. Further, as described above, the sprayed coating layer 16 is preferably formed up to the brazing portion 20 in order to prevent the tip 19 from falling off.

As shown in Table 1, the present inventors produced samples of Examples 1 to 11 under various conditions in the present invention, and also produced samples of Comparative Examples 1 to 4 to perform various evaluation tests. I went.

Hereinafter, description will be given with reference to Table 1.

[0065]

[Table 1]

First, Examples 1 to 11 and Comparative Examples 1 to 4
Each sample will be described.

<Preparation of Thermal Spraying Powder Used in Examples 1 to 11> First, 70% by weight based on the total weight of the cermet powder.
WC powder (average particle size 10 μm), 20% CrC powder (average particle size 5 μm), and 10% Ni powder (average particle size 3 μm) were mixed, and a 3.6% PVA aqueous solution was added thereto, The slurry was prepared by thoroughly stirring. This slurry has a particle size distribution width of 5 to 7 using a spray granulator or the like.
Spherical granular powder was prepared so as to have a particle size of 5 μm, degreased in an argon atmosphere in a vacuum sintering furnace, and then at 1250 ° C.
Sintered for 5 hours. The powder after sintering was crushed using a ball mill and then classified using a vibrating screener and an airflow classifier to prepare a cermet powder WC / 20CrC / 10Ni powder having a particle size distribution width of 15 to 45 μm. .

Separately from the cermet, Ni powder and Ni-20Cr powder (both having an average particle size of 3 μm)
Were classified in the same manner as the cermet powder to prepare a metal powder having a particle size distribution width of 15 to 45 μm.

For each powder obtained by the above method,
90% WC / 20Cr based on the total weight of the thermal spray material
C / 10Ni powder and 10% Ni powder or Ni-2
0Cr was mixed in a V-type mixing device to prepare the following thermal spray materials.

Thermal spray material A: WC / 20CrC / 10Ni
+ 10% Ni (Examples 1, 2, 4 to 11) Thermal Spray Material B: WC / 20CrC / 10Ni + 10%
(Ni-20Cr) (Example 3) <Preparation of conventional thermal spray powder used in Comparative Example 4> 88% WC powder (average particle diameter 2
[mu] m) and 12% Co powder (average particle size 3 [mu] m) were mixed and crushed and classified in the same manner as the above cermet powder, and the following thermal spray material was prepared with a particle size distribution of 15 to 45 [mu] m.

Thermal Spraying Material C: WC / 12Co (Comparative Example 4) As the build-up material D of Comparative Example 3, HF-350.
(Manufactured by Kobe Steel, Ltd.) was used.

<Blasting Treatment> For the purpose of enhancing the adhesiveness of the sprayed coating layer, the tip of Example 9 and the tip of Example 11 and the cutter bit body were blasted in advance on the surface to be sprayed. The conditions for blasting are as follows.

Blasting conditions Blasting machine: FD-5-T type (manufactured by Fujikikai Co., Ltd.) Discharge pressure: 4 kg / cm ² material: A # 40 grit (trade name, manufactured by Saint-Gobain Ceramics Materials Co., Ltd.) Distance : 100 mm Incidence angle: 30 ° <Sample content and thermal spraying conditions> Using the thermal spraying materials A, B and C or the cladding material D, Examples 1 to 11 and Comparative Examples 1 to 4 by performing thermal spraying or cladding. The sample of was produced. The sample contents and thermal spraying conditions are as follows.

Contents of Samples Examples 1, 4 to 7: The thermal spray material A was sprayed on the entire outer surface of the cutter bit body having S25C as a base material.

Example 2: A thermal spray material A was sprayed on the entire outer surface of a cutter bit body having S45C as a base material.

Example 3: A thermal spray material B was sprayed on the entire outer surface of a cutter bit body having S25C as a base material.

Example 8: A chip having a cemented carbide (E5 type) as a base material, the thermal spray material A being sprayed on the outer surface of the chip, and attached to a cutter bit main body having a S25C base material.

Example 9: After a chip having a cemented carbide (E5 class) as a base material was blasted, the thermal spray material A was applied to the outer surface of the chip.
Which is sprayed on and attached to the cutter bit body whose base is S25C.

Example 10: A chip having a cemented carbide (E5 type) as a base material was attached to a cutter bit body having S25C as a base material, and then a thermal spray material A was sprayed on the outer surface of the chip and the cutter bit body. thing.

Example 11: A chip made of cemented carbide (E5 type) as a base material was attached to a cutter bit body made of S25C as a base material, and the whole body was blasted. Then, thermal spraying was performed on the outer surface of the chip and the cutter bit body. Material A sprayed.

Comparative Example 1: A cutter bit based on S25C.

Comparative Example 2: A chip having a cemented carbide (E5 type) as a base material mounted on a cutter bit body having S25C as a base material.

Comparative Example 3: A chip made of cemented carbide (E5 type) as a base material was attached to a cutter bit body made of S25C as a base material, and the whole material was padded with a padding material D.

Comparative Example 4: A tip having a cemented carbide (E5 type) as a base material was attached to a cutter bit body having S25C as a base material, and then a thermal spray material C was sprayed on the outer surface of the chip and the cutter bit body. thing.

-Spraying conditions Thermal sprayer: TAFA HVOF thermal sprayer JP-5000 Oxygen flow rate: 1500scfh Kerosene flow rate: 6.0 gph The evaluation method of these samples is as follows.

<Abrasion Resistance Test in Wet Environment> Samples of Examples 1 to 11 and Comparative Examples 1 to 4 were used in Japanese Patent Application Laid-Open No. 200
Using the wet abrasion tester described in Japanese Patent Publication No. 0-180331, the abrasion amount (m of the carbon steel STKM12C, which is a reference sample, is measured.
calculating the wear amount of each sample (mm ³⁾ for m ^3), by averaging the three results of tests conducted to evaluate the abrasion resistance of each sample under a wet environment. The test conditions and criteria are as follows.

Test condition Polishing material: A # 8 (trade name, manufactured by Saint-Gobain Ceramics Materials Co., Ltd.) Concentration of polishing material in slurry: 80% by weight Test time: 200 hours Swing distance: 5.67 × 10 ⁵ mm ・ Judgment criteria ◎: Less than 0.1 ○: 0.1 or more and less than 0.5 ×: 0.5 or more ・ Results All Examples 1 to 11 have resistance to wet environment compared to Comparative Examples 1 to 4. Excellent wear resistance. Therefore, according to the excavating cutter bit of the present invention, the continuous excavable distance is significantly improved.

<Abrasion resistance test in a dry environment> For the samples of Examples 1 to 11 and Comparative Examples 1 to 4, using a Suga type abrasion tester (described in JIS H8682), the wear amount of SS4400 as a reference sample ( The wear resistance (mm ³ ) of each sample with respect to mm ³ ) was calculated, and the wear resistance of each sample in a dry environment was evaluated by averaging the test results of three times. The test conditions and criteria are as follows.

Test conditions Abrasive paper: SiC # 180 Load: 3.15 kgf Swing frequency: 400 times Criteria ◎: Less than 0.05 ○: 0.05 or more and less than 0.1 ×: 0.1 or more Results The wear resistance of Examples 1 to 11 under the dry environment is superior to that of Comparative Examples 1 to 4.

<Spraying Yield Test> With respect to the samples of Examples 1 to 11 and Comparative Example 4, the weight increase of the sample due to thermal spraying was measured, and the thermal spraying yield was evaluated as a ratio to the weight of the supplied thermal spraying material. The criteria are as follows.

Criteria ◎: 30% or more ○: 20% or more and less than 30% ×: less than 20% ・ Results All samples meet the criteria, but the spray angle is 50.
The sample of Example 7 having a temperature of 6 ° is slightly inferior to the other samples. Therefore, considering the spray yield, the spray angle is 50.
It is preferably equal to or greater than 90 °, and most preferably equal to 90 °.

<Adhesiveness between Substrate and Thermal Spray Coating> Examples 1 to 1
A peeling durability test was performed on the samples of 1 and Comparative Example 4 using the falling ball tester A shown in FIG. Height (L) 1m
As a result, the number of drops (n) in one test was 500 pieces at a collision angle (θ) of 60 ° with respect to each sample installed as the sample piece 2 through the guide pipe 1 having an inner diameter (d) of 29.3 mm. Steel ball c (diameter D: 9.5 mm, weight 3.32 g) was continuously dropped and collided, and the number of times of durability until the thermal spray coating on the surface of the sample was cracked or peeled off was counted. The adhesion between the substrate (cutter bit body) and the thermal spray coating was evaluated by averaging the results of four tests. The criteria are as follows.

Judgment criteria ◎: 50 times or more ○: 30 times or more and less than 50 times ×: less than 30 times ・ Results Comparative Example 4 does not satisfy the criteria, but Examples 1 to 11 all satisfy the criteria. . Examples 4, 7, 8, 10
Is slightly inferior to the other examples, but the following reasons can be considered. First, in Example 4, the film thickness is thin. The thicker the sprayed coating is, the more advantageous it is for the adhesion, and the results of this test show that the film thickness is preferably 50 μm or more. Further, in consideration of processing time, cost and the like, the film thickness of the thermal spray coating layer formed on the outer surface of the cutter bit body is most preferably about 300 to 400 μm.

Next, in Example 7, the spray angle is small. Similar to the thermal spray yield, the adhesive force is also excellent as the thermal spray angle approaches 90 °. Therefore, also from this point, it is understood that the spray angle with respect to the cutter bit body is preferably 50 ° or more, and most preferably 90 °.

Next, the blast treatment is not performed in the eighth and tenth embodiments. Since the adhesion of the thermal spray coating layer to the tip made of cemented carbide is smaller than the adhesion to the cutter bit body made of carbon steel,
The thermal spray coating layer formed on the outer surface of the chip is peeled off. Therefore, when the chip is attached to the cutter bit body, it is preferable to blast the sprayed surface before spraying.

<Impact resistance (chip)> The samples of Examples 1 to 11 and Comparative Examples 1 to 4 were subjected to an impact resistance test (chip) using a falling ball tester B shown in FIG. From a height (L) of 1.5 m, a falling sphere C (φ12 mm) having a large curvature applied with a load of 3 kg is dropped onto each sample set as the test piece 2 at an angle of collision angle (θ) of 90 °. ,
The number of times of durability was counted until the sample was collided and cracked or peeled off on the sample itself or the sprayed coating on the sample surface. The impact resistance of the sample was evaluated by averaging the test results of four times. The criteria are as follows.

Criteria A: 50 times or more O: 30 times or more and less than 50 times x: less than 30 times-Results Examples 1 to 11 and Comparative Examples 1 and 3 satisfied the criteria, but Comparative Example 2, No. 4 could not meet the standard. This is because the chip made of cemented carbide is fragile and chipped. In addition, Examples 8-11
Is slightly inferior to Examples 1 to 7, but this is because the adhesive force between the chip and the thermal spray coating layer is slightly inferior to the adhesive force between the cutter bit body and the thermal spray coating layer. Conceivable. However, also in Examples 8 to 11, the impact resistance standard is satisfied.

<Tip dropping test> With respect to the samples of Examples 8 to 11 and Comparative Examples 2 to 4, assuming the impact that is actually received during excavation, the tip attachment portion is subjected to an impact equivalent to the impact applied during excavation. It was repeatedly added as many times as required for the length, and it was confirmed whether or not the chip had fallen off. The criteria are as follows.

◯: No falling off ×: Falling off-results In Examples 8 to 11 and Comparative Examples 3 and 4, no chips fell off, which satisfied the criteria. Only in Comparative Example 2, the chip fell off and the standard could not be satisfied.

<Comprehensive Evaluation> Comprehensive evaluation was performed on all the test results described above in consideration of workability and cost.

As shown in Table 1, Examples 1 to 11 have some superiority and inferiority, but satisfy the judgment criteria of all the tests, indicating that they are excellent as excavating cutter bits.

On the other hand, with respect to Comparative Examples 1 to 4, there are tests that do not meet the respective criteria, and it is understood that when compared with Examples 1 to 11, the cutter bit for excavation is inferior.

Up to now, the cutter bit has been shown and described as a tooth bit type, but the present invention is not limited in this respect, and the roller bit 30 shown in FIG.
Alternatively, it can be applied to all types of cutter bits such as the shell bit 31 shown in FIG. When applied to the roller bit 30 and the shell bit 31, as in the case of the teeth bit, the thermal spray coating layer 35 is formed on the outer surface of the cutter bit body 33 without attaching the tip 32.
May be formed, or the chip 32 and the cutter bit body 3 may be formed.
The thermal spray coating layer 35 may be formed on the outer surface of the chip 3, or the thermal spray coating layer 35 may be formed only on the outer surface of the chip 32. 6A and 6B show an example in which the thermal spray coating layer 35 is formed on the outer surfaces of the tip 32 and the cutter bit body 33.

Further, although the cutter bit of the shield machine has been described so far, the present invention is not limited in this respect, and can be applied to the cutter bit of all types of underground excavators such as TBM and road header. is there.

Further, the cermet powder used for producing the thermal spraying powder has been described as having WC, CrC and Ni as the main components, but the cermet powder having WC, Co and Cr as the main components is used. The same effect can be obtained by using instead.

[0106]

In summary, according to the present invention, it is possible to continuously excavate a long distance without exchanging the cutter bit, and it is possible to shorten the construction period and reduce the cost. It is a thing.

[Brief description of drawings]

FIG. 1 is a front view of an excavating cutter bit according to an embodiment of the present invention.

FIG. 2A is a front view of a drill bit for excavation according to an embodiment of the present invention, to which a plate type tip is attached. (B) is
A cutting bit for excavation according to an embodiment of the present invention,
It is a front view of the excavation cutter bit with which the insert type tip was attached.

FIG. 3A is a front view showing a form in which a thermal spray coating layer is formed only on the outer surface of the tip in the excavating cutter bit to which the plate type tip is attached.
(B) is a front view showing a form in which a thermal spray coating layer is formed only on the outer surface of the tip in the excavating cutter bit to which the insert type tip is attached.

FIG. 4 is a schematic view of a falling ball tester A used for a peeling durability test of a sprayed coating.

FIG. 5 is a schematic view of a falling ball tester B used in an impact resistance test.

FIG. 6A is an upper half sectional front view showing an example in which the present invention is applied to a roller bit. (B) is a front view showing an example in which the present invention is applied to a shell bit.

FIG. 7 is a front view of a conventional excavating cutter bit.

[Explanation of symbols]

10 excavating cutter bits 15 cutter bit body 16 Thermal spray coating layer

Continued front page    (72) Inventor Tsuyoshi Itsukaichi             2-chome, 1 territory, Nishibiwajima-cho, Nishikasugai-gun, Aichi prefecture             Address 1 Fujimi Incorporated             In Ted (72) Inventor Satoru Osawa             2-chome, 1 territory, Nishibiwajima-cho, Nishikasugai-gun, Aichi prefecture             Address 1 Fujimi Incorporated             In Ted (72) Inventor Masao Asakuma             4-11 Yuhigaoka-cho, Tennoji-ku, Osaka City, Osaka Prefecture             Morimoto group (72) Inventor Hironobu Tatsumi             4-11 Yuhigaoka-cho, Tennoji-ku, Osaka City, Osaka Prefecture             Morimoto group F-term (reference) 2D054 BB05                 4K031 AA05 AB03 BA01 CB21 CB22                       CB45 DA01

Claims (4)

[Claims] 1. In a cutter bit for excavation used in an underground excavator such as a shield machine, a cutter bit body is formed of carbon steel, chrome molybdenum steel or the like, and cermet powder is formed on the outer surface of the cutter bit body. , Ni
Alternatively, a cutter bit for excavation, characterized in that a spray coating layer is formed by spraying a spraying powder in which Ni and a metal powder containing Cr are mixed. 2. A cutter bit for excavation according to claim 1, wherein a tip made of cemented carbide or the like is attached to the main body of the cutter bit, and the sprayed coating layer is formed on the outer surface of the main body of the cutter bit and the tip. 3. The cutter bit for excavation according to claim 1, wherein the sprayed coating layer is formed on the outer surface of the tip made of cemented carbide or the like, and is attached to the cutter bit body. 4. Tungsten carbide, chrome carbide and Ni, or tungsten carbide, Co
And cermet powder containing Cr as the main component, and Cr and N
A metal powder in which the sum of i accounts for 90% or more with respect to the total weight of the metal powder, and the content of Cr is 0 to 55% with respect to the total weight of the metal powder, The sprayed coating layer is formed by spraying a spraying powder which is added and mixed so that the content is 80 to 97% and 3 to 20%, respectively. Cutter bit for excavation.