JPH0626621Y2 - Casing bit and drilling cutter incorporating the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a casing bit and an excavating cutter incorporating the same, and particularly to an improved casing bit mounting structure.

(Prior Art) Conventionally, this type of casing bit has been disclosed in, for example,
186344 and Japanese Utility Model Laid-Open No. 62-176286. In the former method, the bit is inserted into the mounting groove of the holder, and the bit is drawn from the rear window hole and fixed by a draw bolt. On the other hand, in the latter, the bit is inserted into the receiving groove of the holder and screwed from the side surface direction.

Further, Japanese Laid-Open Patent Publication No. 63-93987 discloses that a cutter bit is attached to an adapter by a wedge element, and a bit is tightened in a recessed receiving groove of a holder in a locked state. -176286 is disclosed.

(Problems to be solved by the invention) However, since the cutter bit disclosed in the first publication is formed in the window hole in the holder, the strength of the main body is weakened and the operation of the draw bolt becomes difficult due to the cutting waste. There was a problem such as.

Further, the cutter bit seen in the second publication requires machining of notches, protrusions, etc. on the cutter body side, and the strength of the cutter body is weak due to the mounting configuration of the mounting bolts, etc., which improves excavation efficiency. There was a problem that I could not hope.

In addition, the one that is attached with a wedge element has a problem that it is easy to remove, but it has a complicated structure, and the one that is bolted into the concave receiving groove has a large blade width. There was a problem of being restricted by.

Therefore, it is an object of the present invention to provide a casing bit in which the bit body is attached to the holder and an excavating cutter in which the casing bit is incorporated in the cutter body.

(Means for Solving the Problem) The present invention has been made in view of the above-mentioned points, and a holder having a substantially rectangular plate shape has a casing bit and a shank portion of a cutter bit attached by a tightening screw. This is an improvement on the premise of a drilling cutter incorporating this.

That is, the holder is formed with first and second mounting groove portions on both side surfaces thereof in a large-small width relationship extending from the front end toward the rear end so as to have an I-shape at least on one end side thereof, and Through holes that respectively open to the mounting groove portions are formed in the central core portion remaining from these mounting groove portions. When the excavating cutter is constructed, this holder is welded and fixed in the mounting recess of the cutter body.

Further, the cutter bit is composed of a head portion and a shank portion, and the shank portion is formed with a central groove portion that fits the central core portion and the mounting groove portion of the holder and a forked portion having a large and small width relationship. Therefore, when the shank portion is inserted into the holder, the head portion is brought into contact with the end surface of the holder, and the counterbore hole and the screw hole formed in the fork portion fit into the through hole of the holder. It is something like this. Further, the fastening screw is inserted from the counterbore hole side of the cutter bit toward the through hole of the holder and the screw hole of the cutter bit in order to attach the cutter bit to the holder.

(Operation) The casing bit of the present invention comprises a cutter bit and a holder. When mounting the casing bit, the forked portion formed on the shank portion of the cutter bit and the central core portion of the holder are fitted together and finally, ,
It is designed to be fixed by tightening screws.
Therefore, the cutter bit and the holder are firmly attached.

Further, the casing bit of the present invention does not have a structure in which the tightening screw is projected from the cutter bit and is not directly screwed into the cutter body, so that the strength of the cutter body is not impaired. .

(Embodiment) An embodiment of a casing bit of the present invention and an excavating cutter incorporating the same will be described below with reference to the drawings.

1 to 3, (1) is a casing bit of the present invention, and the casing bit (1) comprises a holder (2), a cutter bit (3) and a tightening screw (4). .

The holder (2) has a substantially rectangular plate shape, and a first mounting groove portion (5a) having a narrow width and a second mounting groove (5b) having a wide width are distributed on both side surfaces thereof. By being formed as described above, the central core portion (6) is left in the central portion. Therefore, the first
Also, the transverse portion where the second mounting groove portions (5a) and (5b) are formed has an I-shaped cross section. And, in this central core (6), the shank part of the cutter bit (3)
A through hole (8) for attaching (7) is provided.

The cutter bit (3) comprises a head portion (9) and a shank portion (7) as shown in FIGS. 6 to 8. In this case, the head portion (9) bulges out more than the shank portion (7), and a drilling tip (10) made of cemented carbide is brazed to the tip thereof. Further, the shank portion (7) of the cutter bit (3) is formed with a central groove portion (11), so that there is a large-small width relationship on both sides thereof.
Moreover, the parts (12a) and (12b) remain. The central groove portion (11) and the forked portions (12a) (12b) are fitted with the central core portion (6) and the mounting groove portions (5a) (5b) of the holder (2) described above.

Further, on the side surface of the forked portion (12a) formed on the shank portion (7), a counterbore hole (13) and a screw hole (14) are formed in a spaced relationship so as to be on the same axis. There is. Then hold the shank part (7) of the cutter bit (3) in the holder.
When inserted into (2), the spot facing hole (13), the through hole (8) and the screw hole (14) are located on the same axis. Therefore, both can be fixed by the tightening screw (4) in the shape of a countersunk bolt. Since the head part (9) of the cutter bit (3) bulges out more than the shank part (7), the head part (9) is brought into contact with the end surface of the holder (2), and therefore the drilling tip It has a structure that can withstand the excavation resistance of (10).

FIG. 4 and FIG. 5 are views conceptually showing an excavation cutter (21) in which a casing bit (1) is incorporated in a cylindrical cutter body (20).

That is, a mounting recess (22) is formed in the cutter body (20), and a casing bit is provided in the mounting recess (22).
The holder (2) of (1) is attached by welding. In this case, the excavating cutter (21) is designed to alternately incorporate right-handed and left-handed casing bits (1).

Further, the tightening screw (4) on the forked portion (12a) side faces the outer peripheral side of the cutter body (20).

(Effect of the Invention) As described above, according to the present invention, in the casing bit including the holder and the cutter bit, the shank portion of the cutter bit and the holder are fitted together,
Since the cutter bit is fixed by the tightening screw, the cutter bit can be reliably attached and the attachment strength can be improved.

Further, with respect to the excavating cutter incorporating this casing bit, since the holder of the casing bit may be welded to the cutter main body, the rigidity of the cutter main body is increased and the excavation efficiency can be expected to be improved. .

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a casing bit of the present invention, FIG. 2 is a partially sectional plan view, FIG. 3 is a side view, and FIG. 4 is a casing bit of the present invention. FIG. 5 is a partial side view, FIG. 5 is a partial side view of an essential part showing an embodiment of an incorporated excavating cutter, FIG. 6 is a front view showing a cutter bit, and FIG. 7 is in FIG. It is sectional drawing obtained along the AA line of FIG. FIG. 8 is a perspective view of a cutter bit. (1)… Casing Bit, (2)… Holder (3)… Cutter Bit, (4)… Tightening Screws (5a) (5b)… Mounting Groove, (6)… Center Core (7)… Shank, ( 8)… Through hole (9)… Head part, (11)… Drilling tip (12)… Between parts, (13)… Spot facing hole (20)… Cutter body, (21)… Drilling cutter (22)… Mounting recess

Claims (2)

[Scope of utility model registration request] 1. A casing bit, wherein a shank portion (7) of a cutter bit (3) is attached to a holder (2) having a substantially rectangular plate shape by a tightening screw (4). Is the central core at least on one end side
The narrow first mounting groove portion (5a) and the second wide mounting groove portion (5b) extending from the front end to the rear end are distributed to both side surfaces so that (6) is left. And the central core portion (6) is provided with through holes (8) that open toward the mounting groove portions (5a) and (5b), respectively, and the cutter bit (3) is excavated. The shank portion (7) comprises a bulging head portion (9) having a tip (10) at the tip and a shank portion (7) extending to the rear end.
The holder, the central core (6) of the holder (2) and the mounting groove
(5a) and (5b) are fitted with a central groove (11) and a forked portion (12a) (12b) having a large and small width relationship, and when this shank portion (7) is inserted into the holder (2) The head portion (9) is brought into contact with the end surface of the holder (2), and the counterbore hole (13) and the screw hole (14) formed in the forked portion (12a) have the holder (2). It fits into the through hole (8) of the cutter bit (4), and the tightening screw (4) is
From the 3) side, through hole (8) of the holder (2), cutter bit (3)
It is characterized in that the cutter bit (3) can be fixed to the holder (2) by being inserted toward the screw hole (14) and screwed into the screw hole (14). Casing bit. 2. A mounting recess (2) for a rotatable cutter body (20).
Holder of casing bit (1) according to claim 1 within 2)
(2) is welded, and the tightening screw (4) on the forked portion (12a) side faces the outer peripheral side of the cutter body (20).