JPS5883790A - Drill 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 discloses a novel configuration of a drill bit used for drilling geological formations such as rocks, which uses sintered diamond at the cutting edge. Fine diamond particles are Co
The diamond sintered body obtained by sintering diamond under stable ultra-high pressure and high temperature using iron group metals such as ferrous metals as a binder is used for cutting tools, wire drawing dies, etc. due to its excellent wear resistance and strength. It is being In recent years, the use of this material as the cutting edge of drill bits for drilling rocks has been considered.
It seems that sufficient results have not yet been obtained for this application. As an example of applying sintered diamond to drill bits, as shown in U.S. Patent No. 4098.862, a large number of disc-shaped sintered bodies are embedded in the bit crown and used as a cutting part that has the function of scraping off rocks. There is something. FIG. 1 shows an example of a diamond sintered body used for this purpose, and numeral 1 is a thin layer of the diamond sintered body, and 2 is a cemented carbide base material joined to this thin layer. A large number of these disc-shaped sintered bodies are inserted around the circumference of the drill crown, and drilling is performed by rotating the bit. Figure 2 schematically shows the action of a single blade to scrape off rock.

1 and 2 in the figure are the same as in FIG. 1, and are fixed to the bit body 8 by brazing or other methods. 4 is the rock to be excavated. At this time, stresses indicated by σ, σ2 in the figure are acting on the diamond sintered part 1. The excavating action of drill bits is mainly based on the action of crushing and digging the rock, as in the case of a tricone bit using a cemented carbide insert, and the action of scraping away, as shown in FIG.

When sintered diamond is used as a cutting edge in this latter type, the life of the cutting edge is almost always in the form of a flake-like defect in the part of the diamond sintered body that contacts the rock, as shown in Figure 8. 1' in the figure.

1.2 is the same as in Figure 1).In particular, in the case of soft rocks such as sandstone that are relatively easy to cut, there are few chips, but when digging into wide and hard rocks such as igneous rocks, most of the cutting edge will be damaged. It is lost as shown in Figure 8.

The present invention was developed as a result of intensive research to eliminate the drawbacks of conventional drill bits that use a diamond sintered body as the cutting edge. This technology succeeded in significantly reducing such defects.

When using sintered diamond in a drill bit, conventionally a large number of disc-shaped sintered bodies as shown in Fig. 1 are arranged around the circumference of the drill crown as schematically shown in Fig. 5. Ta. The excavation cross-sectional area per blade at this time is shown in Figure 4 (a).
It becomes as shown.

The figure shows the state of excavation by eight adjacent blades with the same diameter. After the first blade (5) has passed - the second blade protrudes by f, which corresponds to the feed amount per blade. The 6th position is excavated, and the 8th blade excavates the 7th position. The excavation cross-sectional area of the second and eighth blades is a crescent-shaped area as shown.

In this case, the tip of the blade in the digging direction (A in Figure 4 (a))
The stress applied to the blade is greatest at this point, and peeling of the diamond sintered body portion as shown in FIG. 8 occurs at this point.

The drill bit of the present invention is characterized in that a sintered body having a polygonal plane is used instead of a disc-shaped diamond sintered body. A regular hexagonal sintered body will be explained as a typical example. As shown in FIG. 7(b), this consists of a diamond sintered body part 18 and a base material 14, and has a regular hexagonal plane. This is arranged on the circumference of the bit crown as shown in FIG. At this time, the blades are arranged so that the blade edges forming an apex angle of 120 degrees and the straight blade edges are arranged alternately.

Figure 4 (b) shows the state of the excavation cross-sectional area per sword in this case. That is, unlike the case (a) in which a disc-shaped sintered body is used, the second blade, which has a straight cutting edge perpendicular to the excavation direction, excavates mainly in the areas B and B', and cuts at 120°. It can be seen that the eighth blade, which has an apex angle of , in the excavation direction, excavates mainly in areas C, C', and D.

That is, excavation is mainly performed using two to eight hexagonal cutting edges having apex angles of 120°.

As described above, the drill bit according to the present invention is characterized in that the region of the cutting edge that acts on drilling is not formed in a circular arc, but has a shape that is sharper than a circular arc. This makes it easier to dig into the rock and reduces excavation stress. Next, the stress in the sintered blade part is dispersed mainly by excavating at a plurality of apex corners. As a result, it can be applied to medium to hard rocks, and it has become possible to greatly reduce chipping of the cutting edge.

The reason why diamond concretions conventionally applied to drill bits have been disk-shaped is thought to be due to manufacturing reasons. That is, since sintering is carried out using an ultra-high pressure and high temperature apparatus, the shape of the sintered body that can most effectively utilize the ultra-high pressure and high temperature generating area of the apparatus is considered to be due to the disk shape. In producing the sintered body having a polygonal plane according to the present invention, a large disc-shaped sintered body 11 is produced using a large ultra-high pressure/high temperature generator, and this is produced, for example, as shown in Fig. 7 0). By dividing and cutting as shown, a large number of sintered bodies as shown in FIG. 7(b) can be obtained. In this case as well, it is most economical to cut into regular hexagonal shapes. However, the features of the invention are not lost in other polygonal shapes. Similar effects can also be obtained by combining a polygonal shape and a conventional disc-shaped sintered body. In addition, it is desirable to arrange the bit crown so that adjacent sintered bodies on the circumference have different acute or obtuse angle cutting edges and straight cutting edges, but two pieces of either Alternatively, changes such as arranging every eight sheets can be made without departing from the spirit of the present invention.

The diamond sintered body used in the present invention is manufactured by sintering diamond powder of 500 μm or less using a binder under ultra-high pressure and high temperature where the diamond is stable. The binder may include iron group metals, carbides, nitrides, borides, silicides, solid solutions or mixtures of metals of groups 4m and 5ae6a of the periodic table, as well as S*CeBaC and the like. The amount of diamond in the pot is 50% by volume or more. , below that, the wear resistance as a bit cutting edge is insufficient. As shown in FIG. 7(B), the polygonal diamond sintered body portion 18 is joined to each member 14 having the same polygonal shape. The base material is 4th a m 5 a of the periodic table.
A hard sintered alloy bonded with e 6 a group is used. The base material and the diamond sintered body are joined directly or through an intermediate layer as described in Japanese Patent Application Laid-Open No. 56-55506 during sintering under extremely high pressure and high temperature. In order to manufacture drill bits using such a diamond sintered body for the cutting edge, it is necessary to use brazing metal at the top of the steel bit body and bond the base metal of the sintered body, or to attach the solder to the base metal of the sintered body beforehand. This is done by creating a recess at the top of the body and press-fitting the base material into the recess. Alternatively, the end portion of the base material and the steel bit body may be melted and joined using a narrow high-energy beam such as an electron beam. The number of blades is appropriately selected depending on the size of the diamond sintered body, the dimensions of the bit, etc., but it is generally preferable to have four or more blades in total.

This will be described in detail below with reference to Examples.

Example 1 A diamond sintered body having a regular hexagonal plane with circumscribed circle diameters of 1 and 8* was prepared. The thickness of the diamond sintered body is 0.
．． During the production of the sintered body, it was ζ-bonded to a base material made of Kago-1296CO alloy having a thickness of 5 mm and 8 mm. Six of these sintered bodies were joined to a steel core bit body having an outer diameter of 65 JIJL using silver solder corresponding to BA/-1. At this time, eight sintered bodies were placed at intervals of 120' on the circumference so that the apex angles of 120 degrees of the regular hexagon coincided with each other in the axial direction at the top of the bit crown. The remaining eight sintered bodies were placed in the middle position so that a straight line, which was one side of the regular hexagon, was perpendicular to the bit axis direction ζ.

This core bit has an unconfined compressive strength of 1400Kf/m” (
7) Andesite was excavated. The bit rotation speed was 120 rpm for 7 minutes, and when the digging speed was measured with the bit load constant, it was possible to dig 20 m at an average rate of 15 strokes/minute.

For comparison, six disk-shaped diamond sintered bodies having the same composition and an outer diameter of 18.8 JLt as shown in Fig. 1 were used (b) to produce core pits of the same size. When andesite was excavated under the same test conditions, the average excavation speed was locm/min, and when the excavation was carried out at 1.6 fFI, cutting edge defects as shown in FIG. 8 occurred on eight of the blades.

Example 2 A core pit similar to that in Example 1 was manufactured using 8 regular octagonal diamond sintered bodies with a circumscribed circle diameter of 13.3 at and 8 disc-shaped sintered bodies with an outer diameter of 1 and 8 JLIL. They were arranged on the circumference of the bit crown at igoo intervals so that the apex angles of the regular octagons coincided with the bit axis direction, and eight disc-shaped sintered bodies were fixed between them. When the same excavation test as in Example 1 was conducted, the excavation speed was 18 m/min, but 10 m/min.
At the time when the excavation was carried out by m, a defect occurred in one disc-shaped sintered body.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a diamond sintered body used in a conventional drill bit. FIG. 2 schematically shows a situation in which rock is excavated using a sintered body as shown in FIG. FIG. 8 shows the state of defects that occur in a drill bit using the sintered body as shown in FIG. FIG. 4 is a diagram for explaining the features of the drill bit of the present invention in comparison with a conventional drill bit, and shows the cross-sectional area of drilling by three adjacent blades. (A) is the conventional case, and (B) is the case of the present invention. Figures 5 and 6 explain the arrangement of the diamond sintered body on the bit crown, and Figure 5 shows the conventional case,
FIG. 6 shows an example of the invention. FIG. 7 explains the method for manufacturing the diamond sintered body used in the present invention, in which (a) is a top view and (←) is a perspective view. 1% 18: Diamond sintered body, 1'; Defected part, 2.
14: Base material 1.8: Bit body, 4: Rock, 5.8
: 1st blade, 6.9: 2nd blade, 7.10: 3rd blade, 11:
Disc-shaped sintered body. Figure Y1 Figure Y2 Figure Base3 Procedural amendment (method) April 1980/, X day Commissioner of the Patent Office Haruki Shimada 1, Indication of the case 1981 Patent Application No. 181954 2, Name of the invention Drill bit 3. Relationship with the person making the amendment Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka Name 018
) President and CEO of Sumitomo Electric Industries, Ltd. Tadashi Kamei Address of agent Address: 6, Sumitomo Electric Industries, Ltd., 1-1-8 Shimaya, Konohana-ku, Osaka, Details subject to amendment Column 7, Name of Toyonaka invention, Amendment The name of the Toyonaka invention in the details of contents is corrected to "drill bit."

Claims (1)

[Scope of Claims] (1) A drill bit, which is a diamond sintered body containing 5096 or more diamonds in volume, and has a plurality of cutting edges fixed to a bit body, each having a polygonal plane. (2. Claim 1m) A drill bit characterized in that acute or obtuse cutting edges formed by polygons and linear cutting edges are arranged alternately around the circumference of the bit. (3) A drill bit according to claims 1 and 2, characterized in that the blade portion having a polygonal flat surface is a blade portion having a regular hexagonal flat surface. ) A diamond sintered body containing 5096 or more diamonds in volume, which has a polygonal acute or obtuse cutting edge and an arcuate cutting edge of the sintered body having a disk-shaped plane. Arranged alternately in a circumferential manner,
A drill bit characterized by: