JPS6023591A - Drill bit for core boring - 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 a core boring drill bit for drilling rock.

[Background of the invention]

In general, geological excavation includes core boring, which extracts the core of the stratum, and non-core boring, which excavates the entire section without extracting the core. In any of the above poling methods, the cutting edge of the drill bit attached to the tip of the boring rod will wear out after digging a certain distance, reaching the end of its life. In the conventional drill bit 1 shown in FIG. 1, whenever the cutting edge 2 becomes worn and the drill bit becomes unusable, it is pulled up from the bottom of the hole along with the boring rod and replaced with a new bit.

Raising and lowering the rod is undesirable as it wastes time and there is a risk of collapse depending on the geology. For this reason, conventional bits that can be replaced at the bottom of the hole without having to pull up the rod have been proposed, but these are mechanically complex or have structures unsuitable for core boring, making them impractical. It wasn't.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a core boring drill bit in which the bit head has a multi-layered structure and the worn upper layer bit-rad is removed to expose the next layer bit head.

[Summary of the invention]

The drill bit for core boring of this invention has an upper layer bit head installed in a superposed state (= installed) on the bit head of the bit body, and a release mechanism for removing the bit head when the upper layer bit head reaches the end of its life. It is built into.

In the above configuration, when the cutting edge of the upper bit head becomes worn, a release mechanism built into the bit body is operated to disengage the bit body and the upper bit head. Then, the upper layer bit head is passed through the boring rod and retrieved, and drilling is continued with the next layer bit head.

[Embodiments of the invention]

The present invention will be described in detail below with reference to the drawings.

A bit head 3 in which diamonds 2 are embedded is provided on the upper part of the cylindrical bit body 1, and a plurality of water grooves 4 are formed in the bit head 3. The inner surface of the main body has a small diameter at the top and a large diameter at the bottom from approximately the middle, and a two-step difference a is formed at the boundary between the two, with a groove 5 continuous to the water groove 4 extending in the direction of the central axis of the bit body. It is set in. Two protrusions 6,6' are formed below the step a for locking an upper ring and a lower ring constituting an upper bit head, which will be described later. The protrusions 6.6' face each other and are located at positions offset by a ring depth in the direction of the central axis (
There are two. Reference numeral 7 denotes a female thread formed on the lower inner surface of the bit body 1 for attachment to the tip of the boring rod 8.

An upper bit head 9 retractable into the bit body is installed above the bit head 3.

The upper bit head 9 will be described in detail below. The upper J-bit head 9 has cutting edges 10, 10' and 10 divided into a plurality of
// It has ...... and a shank 11 inside it.
is fixed. The shank 11 is the bit head 3
By fitting into the water groove 4 of the bit head 3, the upper bit head 9 is held in an overlapping state on the upper part of the bit head 3. One end of the leg 12 is fixed to the shank 11 of each cutting blade, and the other end is attached to the outer periphery or end surface of the ring 13 by welding.

Note that the legs may be formed integrally with the ring.

The relationship between the legs and the ring will be explained with reference to FIG.
0'... is given elasticity toward the center line of the bit body 1 so that it can be pulled out through the bit body. That is, the normal state of the leg 12 is that the cutting edge 10.1
0' . . . is located in the central axis direction of the bit body 1 to such an extent that a part of the bit body 1 does not get caught on the bit head 3 of the bit body and become unable to be pulled out. The ring 13 to which the lower end of the leg 12 is fixed consists of an upper ring 13a and a lower ring 13b, and each ring has a cut 1.
4a and 14b are formed, and has a structure that can be expanded or contracted in the circumferential direction. On the other hand, the legs 12 are attached to the side surface of the ring opposite to the cuts 14a and 14b of the ring. That is, in this embodiment, four legs 12 are attached to the side surfaces of the rings opposite to each cut in the upper and lower rings 13a, 13b. In this state, the legs 12 are arranged equal to the spacing between the water grooves 4 provided in the bit head of the bit body. Note that the legs may be made of, for example, a shape memory alloy, as long as they are located in the central axis direction of the bit body under certain conditions.

The reason why the legs were placed on the side of the ring opposite to the cut in the ring will be described below. The ring is installed inside the bit body with the cut widened, so if you fix the leg to the ring regardless of the cut, the distance between the leg near the cut and the leg far from the cut will change when the ring is contracted. may become uneven and cause inconvenience when folding.
Stable collection becomes impossible. However, if the legs are fixed on the semicircumference of the ring away from the cut, the change in the spacing between the legs due to the widening of the cut can be ignored. From this, leg 1
2 is divided into two rings 13a and 13b, and the legs are attached to each ring on the side of the semicircle of the ring facing the cut. Of course, if the arrangement of the legs with respect to the ring is considered to such an extent that the change in the interval between the legs does not cause any problems when the diameter of the ring is expanded (installed), it is possible to adopt a structure in which the legs are fixed to one ring having the cut 14C. (Fig. 4b) Naturally, in that case, only one protrusion is formed on the inner surface of the bit body.

A release mechanism 15 for releasing the engagement between the bit body 1 and the upper bit head 9 is provided within the bit body 1. The mechanism includes a plurality of wedges 17 on an annular plate 16 of a constant width.
This wedge 17 is slidably fitted into a groove 5 formed on the inner surface of the bit body.

Next, an embodiment of the recovery mechanism for lifting the drill bit to the ground according to the present invention will be described with reference to FIG.

The recovery mechanism 18 is suspended from the ground to the bottom of the hole inside the boring rod 8, and uses its own weight to release the release mechanism 15.
The upper bit head 9 is removed from the bit body and recovered to the ground.

That is, the recovery mechanism 18 consists of a base 19 to which the wire is connected, a shoulder 20 that pushes the release mechanism 15 toward the bottom of the hole, and a recovery section 21 provided at the front of the layer. Said collection section 2
Reference numeral 1 denotes a cylindrical body slightly smaller than the inner diameter of the boring rod 8, the tip of which has a conical shape, and a Kawasaki-shaped cutting blade receiver portion 24 is provided at the tip. Upper and lower rings 13a and 1 of the upper bit head 9 are located in the middle of the recovery section.
A recess 23 for hooking 3b is formed.

What is shown in FIG. 6 is another embodiment of the recovery mechanism.

This retrieval mechanism moves from the fitting part 25 of the ring to the conical part 2.
6 are continuously formed, and a receiving portion 27 for the cutting blade 10 is provided at the tip of the conical portion, and a collecting portion is provided with a large diameter portion 28 at the tip.

The incorporation of the above-mentioned upper layer bit head into the bit body will be described below.

The upper layer bit head 9 is inserted through the lower end opening of the bit body 1, and the cutting edges 10, 10', . . . portions of the head are exposed above the bit head 3 of the bit body. Then, the shank 11 provided on the back surface of the cutting edge of the upper bit head is fitted into the water groove 4 of the bit head to overlap the cutting edge of the upper bit head on the cutting edge of the bit head. At this time, the legs 12 fixed to the shank fit into the grooves 5 formed on the inner surface of the bit body and the water grooves 4 formed on the cutting edge portion of the bit head. In this state, ring 1 at the bottom of the leg
The cuts 14a and 14b of 3a and 13b are expanded against their elasticity, and an elastic restoring force is applied to the side surface of the protrusion 6.6' formed on the inner surface of the bit body at the end of the expanded ring. At the same time, the upper end of the ring abuts against the step a. After that, the lock release mechanism 15 is opened from the lower end opening of the bit body.
The annular plate 16 is fitted, and the plurality of wedges 17 fixed to the annular plate are inserted so as to be guided into the grooves 5 to complete the assembly.

Next, the operation of the drill bit of the present invention will be explained.

When the above-mentioned drill bit 1 is attached to the tip of the boring rod 8 and drilling is performed, the upper layer bit head 9 first performs drilling. At this time, the cutting edge is 1O110'...
Since the shank 11 fixed to the back side of the bit body fits firmly into the water groove 4 formed in the head of the bit body and receives vertical load, the upper bit head falls off from the bit body, making it impossible to dig. Whatever happens will happen.

Furthermore, the stepped portion a acts as a stopper for the ring 13 to be pulled out even when the bit body moves in the vertical direction.

If the bit is dug for a certain length under the above conditions, the upper bit head will wear out and reach the end of its life. At this stage, the core tube (not shown) is pulled up and the recovery mechanism 18 is lowered into the boring rod 8. Then, at the shoulder 2°, the annular plate 1 of the release mechanism 15
6, the annular plate 16 moves forward (towards the bottom of the hole).
As the wedge 17 of the annular plate interposes between the ring 13 and the bottom force of the groove 5, the ends of the cuts 14a, 14b of the ring and the protrusion 6.6' are disengaged from each other. by this,
When the upper bit head 9 becomes ready to move forward, the ring simultaneously contracts in diameter and enters the recess 23 of the collecting section 21. In this case, if the bit is slightly lifted from the bottom of the hole, the recovery mechanism will further descend, pushing the ring forward and pushing the upper bit head toward the bottom of the hole. As a result, the upper bit head is released from restraint by the water groove 4 of the bit body, and is folded to the extent that it can pass inside the bit body due to the elasticity of the legs. If the recovery mechanism is pulled up in this state, the upper bit head can be recovered to the ground.

As described above, according to the present invention, the upper layer bit that has reached the end of its service life can be removed by operating the release mechanism from the ground without having to pull up the boring rod. The number of pull-ups can be reduced, and since the upper layer bit head is installed in a superimposed state on the bit head of the bit body, the cutting edge of the next layer bites into the back surface of the upper layer cutting edge, so the upper layer can be removed by drilling. It can prevent misalignment due to lateral (rotational) forces applied to the bit head.
It has excellent advantages such as being able to maintain a stable wearing condition at all times.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a conventional drill bit, FIG. 2 is a sectional view of the drill bit of the present invention equipped with an upper bit head, and FIG. 3(a) is a partial sectional view of the bit body of FIG.
Figure 4 (b) is a sectional view taken along line xx' in (a), and Figure 4 (a).
(b) is an explanatory diagram of the legs of the upper bit head, FIG. 5 is a schematic diagram of the recovery mechanism, and FIG. 6 is a schematic diagram of another embodiment of the recovery mechanism. 1...Bit body, 3...Bit head, 4.
...Water groove, 6.6'...Protrusion, 9...Top I
-Bit head, 10.10'...cutting edge part, 12
...Leg, -13...Ring, 15...Release mechanism,
18... Collection organization, agent Tatsuyuki Unuma (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 7 Figure 4 @ 5 (2) Figure 6 483-

Claims (1)

[Claims] A cylindrical bit body having a bit head with a cutting edge provided on the upper part, a cutting edge portion mounted on the bit head in an overlapping state, a ring that engages with a protrusion on the inner surface of the bit body, and the ring. 1. A drill bit for core boring, comprising: an upper bit head including a leg that connects a cutting edge; and a release mechanism for releasing the engagement between the protrusion and the ring within the bit body.