JPH08170482A - Excavating bit and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide an excavating bit excellent in wear resistance and mechanical strength at the time of excavation while reducing the number of manufacturing processes. CONSTITUTION: Sintering powder material 11-13 are filled in a sintering die 30, with such blending gradation that the content of a Co binder is higher at the base end side part than the tip side part of a vertex member 10. Or powder material 11 with Co as a binder is filled in the tip side part of the vertex member 10, and powder material 12, 13 for hard metal sintering with Fe or Ni as a binder are filled in the other part in the sintering die. A shank member 20 is brought into pressure contact with the powder material 13 to perform sintering while applying pressure. As a result, the vertex member 10 with such hardness inclination that hardness is higher toward the tip side and tenacity is higher toward the base end side is integrally fusion-connected to the shank member 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit provided at the tip of an excavator and used for excavating rock or rock, and a method for manufacturing the bit.

[0002]

2. Description of the Related Art A drill bit of this type typically comprises, as shown in FIG. 4, a tip 1 as a cutting edge and a shank 2 which is a base body for holding the tip. The tip 1 is the main body that destroys the connective structure of rock, etc., and it is necessary to have a very high hardness, so cemented carbide is used, and the shank 2 is made of carbon steel or nickel-chromium-molybdenum steel ( Hereinafter, Ni-Cr-Mo steel) is used.

[0003] The above-mentioned excavation bit is conventionally manufactured through the following steps. (1) First, a shank 2 is cut out by cutting a material round bar made of carbon steel or Ni-Cr-Mo steel, and heat treatment (vacuum quenching and vacuum tempering) is performed to enhance the hardness and toughness of the entire shank 2. . (2) Next, a separately prepared cemented carbide (for example, JIS H5
Molten silver brazing material or brass brazing material 3 is applied to the chip 1 made of 501 G1 to 501) and fitted into the hole 2a formed at the tip of the shank 2. (3) The brazing filler metal 3 is re-melted by heating the mating product obtained in this step to 700 to 900 ° C. again, and the gap between the hole 2 a and the chip 1 is filled. (4) Next, the substances adhered to the surfaces of the chip 1 and the shank 2 by the brazing filler metal or the like from the hole 2a are removed by high-speed spraying (shot peening) of steel grains. (5) Further, a portion of the shank 2 in the vicinity of the tip 1 is partially hardened by induction hardening to recover the hardness reduced by the heat history when the brazing filler metal 3 is remelted in the heating step (3). There is also. (6) Polish the surface and paint.

[0004]

However, the method of manufacturing a drill bit according to the prior art has the following problems.

A. Since many steps as described above are required, the work is complicated, and brazing in the steps of (2) and (3) is an operation that requires skill, so it is unavoidable that there will be large variations in quality. . b. The brazing filler metal 3 needs to be completely filled in the gap between the tip 1 and the hole 2a of the shank 2, but due to air or the like trapped during the press-fitting of the tip 1, the tip 1 and It is unavoidable that a certain amount of voids are generated between the holes 2a, and when actually cutting the product and observing the cross section, the brazing filler metal 3 is filled only to about 70 to 80%. Therefore, there is a large variation in bonding strength, and there is a risk of damage due to insufficient holding strength for the chip 1 during excavation. c. Since the chip 1 is heated in the air, the structure of the cemented carbide forming the chip 1 is thermally deteriorated (occurrence of the η phase) and the wear resistance is deteriorated. d. When used under severe conditions, the bit that holds the chip by brazing raises the surface temperature of the bit to 700 to 800 ° C due to frictional heat and reaches the softening temperature range or melting point of the brazing filler metal 3. In some cases, the holding ability of the shank 2 with respect to the tip 1 is reduced, and the tip 1 may fall off. Also,
Due to manufacturing restrictions, the maximum hardness of shank 2 is H _R C4
It is only about 5 to 50, and since the supporting shoulder portion 2b also comes into contact with the earth and stones in the ground at the time of use, the supporting strength for the chip 1 is also reduced due to wear of this portion. e. Since not only the tip 1 but also the support shoulder portion 2b of the shank 2 is worn, if the wear progresses to some extent, it is necessary to replace the entire bit, which is uneconomical. f. The higher the hardness, the better the excavation performance of chips for crushing debris and rock, but the axial direction from the tip to the base end requires load-bearing characteristics (toughness) against vibration, shock, etc. In general, hardness and toughness are inversely proportional. In the conventional manufacturing method, since the entire chip has to be manufactured as a bulk material having uniform physical properties, depending on the quality of the ground or the like to be excavated, the chip focusing only on hardness may be destroyed by the load. is there. Therefore, when excavating such a ground, it is necessary to use a chip with a low hardness and an improved toughness, which complicates the handling.

The present invention has been made under the circumstances as described above, and its technical problems are to reduce the number of manufacturing steps and to have excellent wear resistance and mechanical strength during excavation. To provide a drill bit.

[0007]

As a means for effectively solving the above-mentioned technical problems, the excavating bit according to the present invention is provided with a crown member which is a main body for excavating rock or a rock and a mounting portion to a device. The crown member is integrally fusion-bonded to the shank member, and is made of a cemented carbide having a hardness gradient that increases in hardness from the base end to the tip on the shank member side. It will be.

As a means for obtaining the above-mentioned excavating bit, the method for manufacturing an excavating bit according to the present invention is based on a method in which a sintered die for molding a crown member is provided with a base rather than a portion on the tip side of the crown member. The powder material for sintering the cemented carbide is filled with a compounding gradient such that the binder content of the end side portion becomes high, or Co is added to the end side portion of the crown member in the sintering die. The powder material for sintering cemented carbide used as a binder was filled, and the powder material for sintering cemented carbide using Fe or Ni as a binder was filled in the other portion in the sintering die, and this was filled. A shank member made of steel is pressed against the base end of the powder material to sinter while pressing the powder material to form a crown member, and the crown member is fusion-bonded to the shank member.

[0009]

In the excavating bit of the present invention, since the hardness of the crown member, which is mainly the excavating member, has a hardness gradient such that the tip end side has a higher hardness, the tongue has a higher toughness on the base end side fusion-bonded to the shank member. It has both hardness and load bearing characteristics required for excavation. Since the base end of the crown member is fusion-bonded to the shank member, the fusion-bonded state will not be destroyed at the temperature of the heat generated by excavation as in the case of brazing. The fusion bonding strength between the member and the shank member does not decrease.

According to the method for manufacturing a drill bit of the present invention, the content of the binder in the portion on the base end side is higher than that on the tip end side of the crown member in the sintering die for forming the crown member. By filling powder material for sintering cemented carbide with such a compounding gradient and performing sintering while applying pressure, the hardness on the distal side is high and the hardness on the proximal side is low and the toughness is high. A crown member having a slope is obtained. As a sintering method at this time, for example, a known discharge plasma sintering method is preferable. Further, a powder material containing Co as a binder is filled in a portion on the tip side of the crown member in the sintering die, and Fe or Ni is filled in other portions.
Also by filling with a powder material using as a binder and performing sintering, it is possible to obtain a crown member having a hardness gradient in which the hardness on the distal end side is high, the hardness on the proximal end side is low, and the toughness is high. At the time of the sintering, a shank member made of a steel material is pressed against the base end of the powder material filled in the sintering die to form the crown member by sintering the powder material and to melt the shank member at the same time. A welding connection is performed, that is, a drilling bit in which the crown member and the shank member are integrated is obtained.

[0011]

1 is a partially cutaway view of a preferred embodiment of a drill bit according to the present invention, that is, this drill bit is made of cemented carbide and is used for rock or rock excavation parts. And a shank member 20 integrally fused to the base end of the crown member 10 and attached to a ground excavation device (not shown) or the like. In addition,
Reference numeral W in FIG. 1 indicates a fusion bonding layer between the base end of the crown member 10 and the shank member 20. The crown member 10 has a substantially conical shape, and the tip side portion 10a having the highest hardness.
Then, a hardness gradient is formed by the base end side portion 10c having the lowest hardness and the middle portion 10b of the intermediate hardness.

In manufacturing the drill bit having the above-described structure, first, as shown in FIG.
WC-Co powder containing 10 to 15% of Co as the first layer powder material 11 is filled in the bottom of the carbon sintering die 30 having the conical concave molding surface 31 corresponding to On top of that, in the middle part of the sintering die 30,
As the powder material 12 of the second layer, WC-Co powder containing 20 to 25% of Co is filled, and the powder material 13 of the third layer is further provided on the upper part of the sintering die 30. As WC-Co powder containing 40 to 45% of Co, as a result of which the Co binder content of the portion on the base end side is higher than that on the tip end side of the crown member 10. Give a slope. Next, as shown in FIG. 2 (B), Ni-Cr-M is formed on the upper surface of the powder material 13 of the third layer to be the base end side portion 10c of the crown member 10.
o The tip surface 21 of the shank member 20 cut out from the bar material of steel, tool steel, die steel, or carbon steel is machined and brought into contact with the powder material 11 to 1 in the sintering die 30 in this state.
While pressing 3 from above and below, a pulse voltage is applied while being sandwiched between electrodes of a discharge plasma sintering machine.

According to this discharge plasma sintering method, extremely high-temperature discharge plasma is generated at the contact portion between the particles of the powder materials 11 to 13 when a pulse voltage is applied, and the particles are instantaneously discharged by the discharge. They are heated and fused together and sintered. At this time, since the material is diffused by the high-speed movement of the ions due to the electric field, the tip side portion 10a where the powder material 11 of the first layer is sintered and the second layer of which the Co content is larger than that of the tip portion 10a. The middle portion 10b in which the powder material 12 is sintered, and the proximal portion 10b in which the powder material 13 of the third layer containing a larger amount of Co than that is sintered are further sintered.
A crown member 10 having a graded diffusion connective tissue whose material continuously changes between c is obtained. Since the WC-Co cemented carbide has a lower hardness and a higher toughness as the Co content is higher, the sintered crown member 10 has a higher hardness toward the distal end side portion 10a and a lower end side. It has a hardness gradient that increases the toughness toward the portion 10c. Sintering conditions of 1,000 to 1,200 ° C., pressure of 100 to 300 kg, and discharge time of 1 to 5 minutes exhibit sufficient hardness and strength.

Further, each particle of the powder material 13 of the third layer to be the base end side portion 10c and the shank member 2 pressed against this.
Even on the contact surface with the tip surface 21 of 0, fusion bonding is performed by the same action as described above, and a fusion bonding layer W having a continuous graded diffusion bond structure is formed. Further, in addition to the simultaneous sintering step of the crown member 10 made of cemented carbide and the fusion bonding step of the crown member 10 and the shank member 20, in the discharge plasma sintering method, a normal sintering method is used. As described above, since a preliminary molding step of previously compression-molding the powder material for sintering into a predetermined shape is unnecessary, the number of steps can be reduced and the manufacturing cost can be reduced.

Co is used as the powder material 11 for the first layer.
WC-Co powder containing 10% of Co is filled, and WC-C containing 20% of Co is used as the powder material 12 of the second layer.
o powder was filled, and WC-Co powder containing 40% Co as the powder material 13 of the third layer was filled and sintered under the above conditions, and the Vickers hardness of the crown member 10 was the tip side portion 10a. At Hv 1,250-1,300,
Hv 800 to 900 in the middle portion 10b, Hv 220 to 500 in the proximal portion 10c, and the hardness change was continuous.

In general, the cemented carbide is a WC-Co alloy and has a composition in which WC particles are bonded with Co as a binder, but Fe or Ni or the like can be used as a binder instead of Co. For example, WC-Co is used as the powder material 11 for the first layer, and the powder material 12 for the second layer is used.
As shown in FIG. 3A, the materials are complemented with each other by giving a material gradient by an appropriate combination such that WC-Ni is used as the powder material and WC-Fe is used as the powder material 13 of the third layer. The crown member shown in FIG.
As is clear from comparison with the crown member obtained by giving a material gradient by i and Fe and sintering, a hardness gradient according to the purpose can be obtained. Further, since Co has a tendency of resource shortage in the world in recent years and the market condition is also soaring, reducing the amount of use of Co by imparting a hardness gradient by the material gradient as described above reduces the manufacturing cost. It greatly contributes to.

The excavating bit thus manufactured can effectively solve the contradictory requirements such as improvement of wear resistance due to high hardness and improvement of load resistance characteristic due to toughness. That is, the crown member 10 that requires excellent wear resistance has the highest hardness at the tip end side portion 10a, and the toughness increases toward the base end side portion 10c. Therefore, it has both excellent excavation performance and excellent load-bearing characteristics against vibration, impact, etc. Since the crown member 10 and the shank member 20 are fusion-bonded and have a continuous inclined structure, vibration during excavation Top member 1 due to load such as impact and shock
The zero is not separated from the shank member 20.

Further, the crown member 10 forms a portion including the supporting shoulder portion 2b of the tip 1 and the shank 2 for supporting the tip 1 in the conventional example of FIG. 4, and the entire contact surface with the rock or the natural ground is formed. Since it bears, the shank member 20 is not worn. Therefore, the situation where the crown member 10 is dropped due to wear cannot occur.

[0019]

According to the present invention, the following effects can be obtained. (1) Since the sintering process of the crown member made of cemented carbide and the fusion bonding process of the crown member and the shank member are performed at the same time, the number of processes is reduced, and skilled manual work such as brazing is performed. Since it is not necessary, the manufacturing cost can be reduced and the quality can be made uniform. (2) Since there is no gap between the crown member and the shank member, unlike the case of brazing, and a continuous diffusion connective structure is formed by fusion at the joint between the crown member and the shank member, excavation is performed. The frictional heat at that time does not soften or melt the joint portion and the crown member does not fall off. (3) Since the crown member is composed of a continuous structure with functionally graded hardness and toughness, complicated measures such as selecting one with high hardness or one with high toughness depending on the quality of the rock or rock to be excavated are required. It is unnecessary. (4) Since the cemented carbide of the crown member is provided with a material gradient of Co, Fe, and Ni to have a hardness gradient, it can be manufactured at a lower cost as compared with the case where the hardness is gradient due to the Co compounding gradient.

[Brief description of drawings]

FIG. 1 is a side view showing a preferred embodiment of a drill bit according to the present invention together with a partially cut cross section thereof.

FIG. 2 is an explanatory view showing an embodiment of a method for manufacturing the excavating bit.

FIG. 3 is an explanatory view comparing the functions of a crown member sintered by giving a Co blending gradient and a crown member sintered by giving a material gradient of Co, Ni, Fe in the above Examples.

FIG. 4 is a side view showing an example of a conventional drill bit together with a partially cut cross section.

[Explanation of reference numerals] 10 crown member 10a tip side portion 10c base end side portion 11 to 13 powder material 20 shank member 30 sintering die

Continued Front Page (71) Applicant 593226135 Hidenori Takahashi 11-1, Kita 19 West, Kita-ku, Sapporo, Hokkaido Inside the Hokkaido Industrial Research Institute (71) Applicant 593175903 Shuichi Kamoda 11-11, Kita-ku Kita-ku, Sapporo (71) Applicant 595177682 Sumitomo Coal Mining Co., Ltd. 3-20-4 Nishishimbashi, Minato-ku, Tokyo (72) Inventor Masahiro Sakai 1-chome, Kita-ku, Kita-ku, Kita-ku, Sapporo 1-chome, Hokkaido 1st Industrial Testing Site (72 ) Inventor Yasuki Miyakoshi 11-chome, Kita-ku, Kita-ku, Sapporo, Hokkaido 1-chome, Hokkaido Industrial Test Station (72) Hidenori Takahashi 11-chome, Kita-ku, Kita-ku, Kita-ku, Sapporo 11-chome, Hokkaido (72) ) Inventor Hidekazu Kamoda 11-chome, Kita-ku, Kita-ku, Sapporo, Hokkaido, 1-11, Hokkaido Industrial Test Station (72) Inventor, Akashi Ho, 1 594, Akabira, Akabira-shi, Hokkaido Sumitomoishi Coal Mining Co., Ltd. 72) Inventor Hiroaki Takayama 1212 Abe, Ochiai Town, Takahashi City, Okayama Prefecture Eagle Engineering Co., Ltd. Okayama in the factory

Claims (3)

[Claims] 1. A shank member that is an excavation main body for rock mass or a rock mass and a shank member that is a mounting portion for a device, and the shank member is integrally fusion-bonded to the shank member and the shank member. A bit for excavation characterized by being made of a cemented carbide having a hardness gradient in which the hardness increases from the base end to the tip on the side. 2. A cemented carbide sintered material having a compounding gradient such that the content of the binder material in the portion on the base end side is higher than that on the tip end side of the crown member in the sintering die for forming the crown member. Is filled with a powder material for use, and a shank member made of steel is pressed against the base end of the filled powder material to sinter the powder material while pressurizing the powder material to form a crown member and the crown member. The method for manufacturing an excavating bit according to claim 1, wherein the shank member is fusion-bonded to the shank member. 3. A sintering material for forming a crown member is prepared by filling a powder material for sintering a cemented carbide with Co as a binder in a portion on the tip side of the crown member in a sintering die for forming a crown member. The powder material for sintering cemented carbide having Fe or Ni as a binder is filled in the other part of the die, and a shank member made of steel is pressed against the base end of the filled powder material to obtain the powder material. 2. The method for manufacturing an excavating bit according to claim 1, wherein the crown member is formed by sintering while pressurizing and the crown member is fusion-bonded to the shank member.