JPS5841180A - Drilling bit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a drilling bit having a composite diamond sintered body on its cutting edge, in which a diamond sintered body mainly composed of diamond is bonded to a support member made of cemented carbide or the like.

Conventionally, oil valves and geothermal wells have been drilled to utilize underground resources such as oil, natural gas, and geothermal heat.

A drilling tool called a drill bit is used for drilling, and cemented carbide has been mainly used as the cutting edge material.

However, although a cemented carbide drill bit can provide sufficient drilling efficiency and long bit life in comparatively soft sedimentary layers among geological formations, the bit life is extremely short in hard sedimentary layers or igneous rocks, and the bit life is very short. The reality was that there were some cases where it was not possible to excavate.

As a raw material, polycrystalline sintered diamond, which is made by sintering diamond particles under ultra-high pressure, has been developed and is beginning to be used.

Polycrystalline sintered diamond was first developed as a tool for cutting metal materials, and a tool in which a polycrystalline diamond layer 1 was bonded to a cemented carbide layer 2 as shown in FIG. 1 was used.

Bits for excavation use are also used in a shape similar to that shown in Fig. 1, and drilling bits with this bit fixed to the cutting edge are used.

However, in excavation applications, unlike ordinary metal cutting, a very large impact is applied to the cutting edge during excavation, and if the stratum is hard, the abrasion effect on the cutting edge is also very severe.

A particular problem is that the impact during excavation is large, and for this reason, when excavating with the bit shown in Figure 2, the sintered diamond layer on the cutting edge is severely damaged, making the bit unusable. This was the biggest problem with drilling bits that used sintered diamond.

The present invention improves the drawbacks of conventional drilling bits using sintered diamond, and provides a long-life drilling bit in which large chips do not occur in the sintered diamond layer at the cutting edge.

The present invention provides a bit body comprising a diamond sintered body containing 60% by volume or more of diamond and a composite diamond sintered body in which support members are bonded to the entire upper and lower surfaces of the diamond sintered body either directly or through an intermediate bonding layer. This drilling bit is characterized in that the cutting edge material is embedded and fixed by brazing, press-fitting, or other appropriate methods.

Now, the effects of the drilling bit of the present invention will be explained with reference to FIG.

Figure 2 focuses on one composite diamond sintered cutting edge of the head of the drilling bit according to the present invention.
As shown in FIG. 2, a composite diamond sintered body 5 having supporting members 2 and 3 on both sides is embedded and fixed in the bit body 4.

In this state, the cutting edge of the diamond sintered body is smooth, and the support member 8 is exposed on the upper surface. When excavation is started in this state, if the support member 3 is made of cemented carbide, the excavation is initially performed in the support member cemented carbide layer.

However, when it comes to hard rock layers, the cemented carbide support member layer on the surface wears out, and the underlying diamond sintered body layer cracks, allowing excavation to be performed using this layer. The supporting member is IVa,
In the case of a Va, Vla group, or other metal layer, the metal layer wears out quickly, and the diamond sintered body layer immediately below is cracked. This state is schematically shown in FIG. 2(b). As the upper support member 8 wears out, the lower diamond sintered body 1 cracks, and its cutting edge 11 begins to perform an excavating action.

In this way, only the cutting edge of the diamond sintered body layer necessary for performing the excavation action is exposed, and the other portions are covered by the support member 8.

The support member 3 is more sticky than the diamond sintered body 1.

Therefore, even if a large impact force is applied to the cutting edge 11 and a chip occurs, the crack will not propagate to the area covered by the support member 8, and the large chip will make this diamond sintered body unusable. There is no need to put it away.

Now, the effect of this support member on preventing large damage is that the support member 3
The stronger the bond between the diamond sintered body 1 and the diamond sintered body 1, the larger the bond.

In this respect, there is a slight problem when the supporting member and the diamond sintered body layer are directly joined.

In other words, if an attempt is made to sinter a diamond sintered body and a supporting member in a state where they are directly joined, the carbon that makes up the diamond will diffuse into the supporting member during sintering, and as a result, carbides will form in the supporting member near the interface. Otherwise, the supporting member near the interface becomes brittle, and the bonding strength between the diamond sintered body and the supporting member decreases considerably.

A diamond sintered body that does not cause this interfacial reaction,
This problem can be solved by using an intermediate bonding layer that firmly bonds the support members to each other, which is more preferable.

As such an intermediate bonding layer, cubic boron nitride (CB
The content of N) is 70% by volume or less, and the remainder is from the periodic table ■a
Ti, Zr, Hf carbides, nitrides, carbonitrides, or borides, a mixture thereof, or a mutual solid solution compound, and 0.1% by weight or more of A and/or Si. It is suitable that it contains This intermediate layer is suitable for supporting materials at relatively low temperatures.
This is because it forms a strong bond with its diamond sintered counterpart and has excellent heat resistance.

Now, the thickness of the support member that prevents large defects in the diamond sintered body layer may be equal to or less than the thickness of the diamond sintered body layer. The diamond sintered body layer usually has a thickness of 0.5 to 1.0
JLiL, but if the supporting member is thicker than this, when the diamond sintered layer is partially exposed as shown in Figure 2 (b), this supporting member will be excavated. This is because there is a possibility that the situation may actually hinder the outflow of small pieces of rock.

In addition, when an intermediate bonding layer is provided, since the purpose of this intermediate bonding layer is to firmly bond the diamond sintered body layer and the support member, it is usually sufficient to use less than 0.5 #IJW, and more Thickness is unnecessary and uneconomical.

Embodiments of the present invention will be described below with reference to FIG.

Embodiment 1゜Figure 3 shows the first embodiment based on the present invention.
A diamond sintered body 7 with a thickness of 0.5 skin is placed on a C-10%Co cemented carbide support member 6, and a sintered diamond body 7 with a thickness of 0JIIu is further placed on top of that.
A composite diamond sintered body 9 to which an IL WC-10% Co cemented carbide support member 8 is bonded is fixed to the bit body 10.

For comparison, a bit of the same shape was also made by fixing a diamond sintered body with a thickness of 0.5 IuL on a WC-10% Co cemented carbide with a thickness of 2 fins. Using this bit, a drilling test was conducted on andesite with a compressive strength of 1,400 K5+/m2. The rotational speed was 140 rpm, the drilling speed was 10 cm/111151, and water was used.

As a result of burning, the bit of the present invention was usable for continued use after 30 minutes of drilling, whereas the comparative bit suffered severe damage to the diamond sintered body portion after 2 minutes of drilling, making it unusable.

Example 2 The second example has the same shape as that shown in FIG. A molybdenum layer with a thickness of 0.2 m is formed on the compact layer, and a 0.05 m thick molybdenum layer is formed on the interface between the cemented carbide support member, each molybdenum layer and the diamond sintered compact layer. This drill bit has a composite diamond sintered body bonded to the cutting edge through an intermediate bonding layer in which % by volume of CBN is bonded with a binder of TiN and 20% by weight of A. In this case, for comparison, a composite diamond sintered body in which a diamond sintered body layer with a thickness of 0.5 thick was formed on a WC-15% Co cemented carbide support member with a thickness of 2 mm was used at the cutting edge. A drill bit of the same shape was also made that was fixed to the .

Using these drill bits, compressive strength l, so o
Ky/cm" granite drill test was conducted. The test conditions were the same as in the first example.

As a result, the diamond sintered compact part of the comparison bit was severely damaged after just 1 minute of drilling, making it unusable, whereas the bit of the present invention was usable even after 20 minutes of drilling.

[Brief explanation of the drawing]

Fig. 1 is an external view of a conventional composite diamond sintered body for drilling bits, Fig. 2 is an external view of the cutting edge of the drilling bit of the present invention, and Fig. 3 is a top view showing an embodiment of the drilling bit of the present invention. (
A) and a front view (B). 1. 7: Diamond sintered body, 2, 6: Lower support member 3.8: Upper support member, 4.10: Bit body, 5.9
= Composite diamond sintered body, 11: Cutting blade 7 old fan 2 concave

Claims (1)

Scope of Claims: (1) A composite diamond sintered body comprising a diamond sintered body containing 60% by volume or more of diamond and a support member bonded to the entire upper and lower surfaces of the diamond sintered body directly or via an intermediate bonding layer. A drilling bit characterized in that the composite diamond sintered body is embedded and fixed in the bit body by a method such as brazing or press-fitting, and is used as a cutting edge. (2) Both supporting members of the composite diamond sintered body are carbides of 1'% Ia, Va, ■A group elements of the periodic table;
Alternatively, it is a cemented carbide made by bonding these mutual solid solution carbides with an iron group metal.
Item 1) Drilling bit. (8) Both supporting members of the composite diamond sintered body are made of metals from group ■a, Va, and Via of the periodic table, Mn, Fe,
The drilling bit according to claim 1, which is made of Co, Ni, Cu, or an alloy thereof. (4) Of the supporting members of the composite diamond sintered body, one is a cemented carbide made of carbides of elements of groups IVa, Va, and Vla of the periodic table or mutual solid solution carbides of these elements combined with iron group metals, and the other is Periodic table IVa IV
a+■A group metals, Mn, Fe, Co, Ni, Cu
or an alloy thereof, according to claim (1). (5) Claims (1) to (4), characterized in that the thickness of one of the supporting members of the composite diamond sintered body is smaller than the thickness of the diamond sintered body layer. drilling bit. (6) In the drilling bit described in claims (1) to (5), an intermediate bonding layer is provided at one or both interfaces between the diamond sintered body at the center of the composite diamond sintered body and the support member. and the intermediate bonding layer has a content of 70% by volume.
The ungrooved cubic boron nitride and the remainder are Ti from group a of the periodic table.
, Zr, Hf carbide, nitride, carbonitride, or boride, or a mixture thereof, or a mutual solid solution compound, and is characterized by containing 0.1% by weight or more of M and/or Si. and drilling bit. (7) The drilling bit according to claim (6), characterized in that the intermediate bonding layer between the diamond sintered body of the composite diamond sintered body and the support member has a thickness of 0.5 μL or less. .