JPH0978986A - Cutter bit with layer tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong a service life by forming plural layers of tip pieces, formed of sintered hard alloys different in material, into a multilayer tip with copper plates inserted between the tip pieces and blazed. SOLUTION: A tip piece 5a with high hardness and low tenacity, a tip piece 5b with medium hardness and medium tenacity, and a tip piece 5c with low hardness and high tenacity are respectively formed using a sintered hard alloy. The tip pieces 5a, 5b, 5c are combined in layers inward in regular order from the tip side, and thin-walled copper plates 6 are inserted between the tip pieces 5a, 5b, 5c. The tip pieces 5a, 5b, 5c are rigidly fixed by brazing through the thin-walled copper plates 6 to form a layer tip 5. The layer tip 5 is rigidly fixed to a base metal 1 by brazing (3) to form a cutter bit 10. Accordingly, even if the tip piece 5a in the outermost tip layer is chipped, the tip piece 5b in the middle layer and the tip piece 5c in the innermost layer are gradually higher in tenacity, so that the service life of the cutter bit 10 can be prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutter bit equipped with a tip made of cemented carbide, among cutter bits attached to various excavating machines such as shield excavators for tunnel excavation and tunnel boring machines.

[0002]

Cutter bits to be attached to various excavators are often brazed at the tip thereof in order to cope with excavation of hard rock or the like.

FIG. 5 shows a conventional example of such a cemented carbide cutter bit 10. In the figure, 1 is a base metal made of steel, and 2 is a cemented carbide chip fixed to the tip of the base metal by brazing 3.

When tunnel excavation is performed using the above-mentioned conventional cutter bit 10, the cutter bit 1 is accompanied by excavation.
In addition to the abrasion of No. 0, the cemented carbide chip 2 may be damaged by an impact load in the soil or hard ground mixed with gravel. FIG. 6 shows a situation in which the single-layer cemented carbide chip 2 as shown in FIG. In the figure, reference numeral 4 is a defective wear portion.

As shown in FIG. 6, when the cemented carbide tip 2 is broken, the steel base metal 1 is easily worn due to its low wear resistance, and the cutter bit 10 is promptly worn as shown in FIG. And the function as a cutter bit is lost. Therefore, in the conventional cutter bit 10, if the cemented carbide tip 2 is damaged, the life becomes extremely short.

In addition to a cutter bit having a single-layer tip as shown in FIGS.
There is a cutter bit as proposed in Japanese Patent No. 97 or Japanese Utility Model Publication No. 6-74697, in which chips made of cemented carbide are divided into multiple layers and brazed to a base metal.

However, since the cutter bit formed by fixing the above-mentioned multilayer chips is constructed by brazing chip pieces made of cemented carbide of the same material in layers, the chip pieces have the same fracture resistance and at the same time. It is easy to cause chipping and has little effect of extending the life of the cutter bit.

[0008] As described above, when the cutter bit 10 loses its function due to chipping or wear, the tunnel excavation capacity is lost. Therefore, excavation of the tunnel is stopped, and the tunnel excavator is retracted once to replace the cutter bit. Is done. At this time, if the face is soft soil, the ground must be frozen with liquid nitrogen in order to make the ground self-sustaining. Therefore, the loss of the above-mentioned cutter bit causes a great delay in tunnel construction and an increase in excavation cost due to replacement and repair of the cutter bit.

An object of the present invention is to extend the life of the cutter bit and reduce the frequency of replacement in a cutter bit equipped with a cemented carbide tip by slowing the progress of wear of the tip of the cutter bit. To improve the efficiency of excavation work.

[0010]

Means for Solving the Problems The present invention is intended to solve the above-mentioned problems, and the gist of the means is to provide a cutter bit for an excavator in which a cemented carbide tip is brazed to a base metal. The cemented carbide chip is a multilayer chip formed by inserting a copper plate between the chip pieces of a plurality of layers chip chips are brazed, each cemented carbide chip piece, hardness, A cutter bit provided with a layered tip characterized by being made of different materials such as toughness.

According to the above means, even if the cutter bit tip piece of the outer layer (the most advanced layer) is broken and worn during excavation work,
Since the chip piece on the inner layer side performs the excavating function, it is not necessary to replace the cutter bit, the step for exchanging the cutter bit can be omitted, and the excavation work is made efficient.

Further, since the chip pieces made of cemented carbide of different materials are combined in layers, the chip pieces having hardness and toughness suitable for the soil layer of the excavated portion are combined in accordance with the change of the excavated soil layer. The chip pieces of multiple layers are not damaged at the same time, which improves the durability of the chip pieces and also excavates the chip pieces of other layers in place of the chip pieces that are damaged or worn as described above. By performing the function, the life of the layered chip as a whole is significantly extended.

In other words, even if the outermost chip piece is missing,
It is possible to sequentially increase the toughness of the next intermediate layer and the next innermost layer. By doing so, the fracture resistance is sequentially increased and the life of the tip and the cutter bit is extended. Furthermore, it is also possible to arrange the material of the cemented carbide chip pieces corresponding to the soil quality of the tunnel construction part, which prevents damage in the gravel layer and minimizes abrasion in clay. Will be possible.

Further, even if one chip piece is cracked,
The crack is stopped at the portion of the soft copper plate inserted between the chip pieces, and the other chip pieces are protected from the crack.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a side view of a cutter bit according to a first embodiment of the present invention.

In FIG. 1, 1 is a base metal made of steel, 5
a, 5b, 5c are chip pieces (A) made of cemented carbide,
(B) and (C). Each of the above chip pieces 5a, 5b, 5
c is combined in a layered manner, a thin copper plate 6 is inserted between the chip pieces and fixed to the base metal 1 by brazing 3, and the chip pieces are also fixed by brazing via the copper plate 6. Has been done.

Furthermore, the cemented carbide chip pieces (A) 5a, (B) 5b, (C) 5c combined in layers are constructed so that at least the hardness and the toughness are different, that is, the materials are different. ing.

A preferred example of the combination of the materials of the chip pieces (A), (B) and (C) is as follows.

Hardness: HV Toughness: KIC (Kgf / mm3 / 2) Tip piece (A) 1200-1300 ≧ 30 (equivalent to JISE3) Tip piece (B) 1100-1200 ≧ 40 (equivalent to JISE4) inside Tip pieces (C) 1000 to 1100 ≧ 50 (corresponding to JIS E5) As described above, the three-layer tip pieces (A), (B), and (C) in this embodiment are tips on the tip side of the cutter bit 10. The piece (A) 5a has the highest hardness and the toughness is low, and the hardness is lower toward the inside and the toughness is higher. It is also possible to mount four or more chip pieces, and in this case, the same material is used.

As described above, in the embodiment of the present invention, each chip piece (A) 5a of the cemented carbide multilayer chip,
The materials of (B) 5b and (C) 5c are changed, and as a suitable combination thereof, the chip piece (A) 5 of the most advanced layer as described above is used.
a is high hardness and low toughness, intermediate layer (B) 5b is medium hardness and medium toughness,
The innermost layer (C) 5c has a combination such as low hardness and high toughness. According to such a combination of materials, even if the tip piece (A) 5a of the most advanced layer is lost during hard ground excavation, the next intermediate layer 5 (B) and the next innermost layer 5 (C) are Since it has a higher toughness in order, it has chipping resistance in any of the layers and the function as a cutter bit is not impaired. Also,
According to the soil distribution of the tunnel construction part, if you arrange the chip piece material made of cemented carbide corresponding to the order of soil quality, the hard ground part is excavated by low hardness and high toughness to prevent damage,
When the soft soil is reached, the material with high hardness and low toughness is excavated to minimize wear, and efficient excavation becomes possible.

Further, since the copper plate 6 is inserted between the respective cemented carbide chip pieces, the adjacent chip pieces 5a-5b are provided.
Even if a crack occurs, the crack stops at the copper plate 6,
Adjacent chip pieces are not adversely affected. That is, the copper plate has an effect of stopping crack growth.

FIG. 2 shows a state in which the cutting edge tip piece (A) 5a of the cutter bit 10 having the above-mentioned layered tip 5 is broken and worn. As shown in the figure, even if the chip piece (A) is missing, it can be excavated by the chip piece (B) 5b of the intermediate layer.

FIG. 3 shows a second embodiment of the present invention. Further, FIG. 4 shows the soil quality of the tunnel construction portion 7 constructed by the cutter bit according to the second embodiment. The soil quality is the gravel layer 8 in the first half and the clay type 9 in the second half. Reference numeral 71 is a constructed tunnel. The cutter bit 10 shown in FIG. 3 is a two-layer cemented carbide chip piece (D), (E) corresponding to the tunnel construction portion 7 of FIG. The hard alloy tip piece (D) 5d and the cemented carbide tip piece (E) 5e of the inner layer are joined by brazing in which the copper plate 6 is inserted.

The cemented carbide chip piece (D) 5d of the outer layer is for excavating the gravel layer 8 and requires chipping resistance, and therefore has a hardness of HV900 to 1000 (lower hardness than JIS E5) and toughness. It is composed of a material with a higher Also,
The cemented carbide chip piece (E) 5e of the inner layer is for excavating the clay 9, and the possibility of chipping is extremely small. Therefore, the hardness is increased to HV 1200 to 1300 (equivalent to JIS E3) to improve wear resistance. Secure.

[0025]

The present invention is configured as described above.
According to the present invention, since a plurality of cemented carbide chip pieces are brazed in layers, even if the cemented carbide chip pieces on the outer layer side are chipped and worn, the chip pieces of the next layer have a drilling function. Therefore, the life is extended as compared with the conventional cutter bit composed of the cemented carbide single-layer tip.

Further, since the chip pieces made of different materials are combined in layers, the material (hardness,
Since chip pieces with toughness etc.) can be combined according to changes in excavated soil quality, the durability of the chip pieces themselves is improved, and multilayer chip pieces are not damaged at the same time. The whole life is greatly extended.

Furthermore, the copper plate inserted between the cemented carbide chip pieces has a crack growth inhibiting effect, and even if a chip piece on the outer layer side cracks, the growth of this crack to the chip piece on the inner layer side is prevented. To be done.

Therefore, according to the present invention, the life of the cutter bit is greatly extended as compared with the conventional one, the frequency of exchanging the cutter bit due to chip loss and wear is reduced, and the efficiency of excavation work and excavation cost are improved. Can be reduced.

[Brief description of drawings]

FIG. 1 is a structural diagram of a cutter bit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a cutter bit is missing according to the embodiment.

FIG. 3 is a structural diagram of a cutter bit according to a second embodiment of the present invention.

FIG. 4 is a soil distribution map of a tunnel construction portion using the cutter bit according to the second embodiment.

FIG. 5 is a structural diagram of a conventional cutter bit.

FIG. 6 is a diagram showing the state of loss of a conventional cutter bit.

[Explanation of symbols]

 1 base metal 3 brazing part 5 layered chip 5a chip piece (A) 5b chip piece (B) 5c chip piece (C) 5d chip piece (D) 5e chip piece (E) 6 copper plate 10 cutter bit

Claims (1)

[Claims] 1. A cutter bit for an excavator in which a cemented carbide tip is brazed to a base metal, wherein the cemented carbide tip has a plurality of layers of chip pieces, and a copper plate is inserted between the chip pieces. A cutter bit provided with a layered tip, characterized in that the cemented carbide tip pieces are made of different materials such as hardness and toughness while being formed into a multilayered brazed tip.