JP2559046Y2 - Dry core bit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry core bit used for openings in walls and floors of concrete buildings and the like.

[0002]

2. Description of the Related Art Conventionally, as such a core bit, there is known a core bit in which a segment chip is fixed to an end of a cylindrical base metal in a circumferential shape. According to this, the bit is rotated to form a circular shape on a concrete building or the like. An opening can be formed.

Recently, as disclosed in Japanese Utility Model Application Laid-Open No. 63-193608, the base body has a double structure, and a groove for introducing a dressing material or a cooling gas is provided therein. A dry core bit that supplies a cooling gas such as nitrogen gas to a cutting point and does not require cooling water has been developed.

According to such a dry-type core bit, drilling can be performed in a place where cooling water cannot be used, and since the surroundings of the construction place are not stained, wide use is expected.

[0005]

However, this dry core bit has a double structure, so that the base metal itself is thick, and accordingly, the diamond segment is also thick and the sharpness is poor, and the structure is complicated. Therefore, the manufacturing cost is high.

[0006] A dry core bit having a shape in which a spiral groove is provided on the inner surface of a cylindrical base and the dressing abrasive is conveyed to the cutting edge by the principle of screw feed is also known. Rotation speed of 50
0 to 1000 r. p. m. And the dressing abrasive material jumps out of the spiral groove, and a sufficient screw feed effect cannot be expected.

Therefore, a problem to be solved by the present invention is to provide a dry core bit that supplies a dressing abrasive and a cooling gas efficiently to a cutting point and is easy to manufacture.

[0008]

A dry core bit according to the present invention comprises a cylindrical base body having a dressing material or a cooling gas insertion hole at a base end thereof, and a circumferential end at a distal end of the base metal body. A plurality of segment chips joined in close contact with each other, and an introduction path that opens inward is provided on a joint surface of the segment chips; and a guide groove that communicates with the introduction path is provided on an inner peripheral surface of the base metal body. The above object has been achieved by forming a guide plate formed in the axial direction and further guiding the dressing material or the cooling gas to the guide groove inside the base metal body.

Here, the guide groove has a depth of not less than twice the abrasive grain diameter of the dressing material injected into the core bit and not more than 50% of the thickness of the base metal body. It can be a conical member or a flat plate arranged in a direction.

[0010]

According to the present invention, the dressing material or the cooling gas inserted from the insertion hole at the base end portion when the dry core bit is used is axially transferred to the inner peripheral surface of the base metal by the centrifugal force of rotation and the action of the guide plate. It is efficiently guided to the formed guide groove, and is further efficiently supplied to the cutting point from the introduction path formed on the joining surface of the segment chip communicating with the guide groove.

[0011]

1A is a sectional view of a dry core bit according to a first embodiment, and FIG. 1B is a bottom view of the same.

The dry core bit 1 of the present embodiment is in close contact with a cylindrical base body 2 having a dressing material or a cooling gas insertion hole 2a at a base end thereof and a distal end portion of the base metal body 2 in a circumferential direction. And a plurality of segment chips 3 joined in a shape.

On the joining surface of the segment chip 3, the supply of the dressing material or the like is sufficiently ensured, and the abrasive grain size of the dressing material is twice or more, and The introduction path 3a having a depth of 1/3 of the thickness of the opening 3a is opened inward.

Further, in the axial direction of the inner peripheral surface of the base body 2,
Four guide grooves 2b communicating with the introduction path 3a are formed at intervals of 90 degrees. Reference numeral 5 denotes a guide plate provided inside the base metal body 2 for guiding a dressing material or a cooling gas into the guide groove 2b, and is a conical member having a distal end directed toward the insertion hole 2a. The outer diameter of the guide plate 5 is substantially equal to the inner diameter of the base metal body 2, and is fixed to the base end of the main body 2 by a stay 5a. A swivel 6 is attached to the insertion hole 2a and is rotatable.

FIG. 3 is an explanatory view showing the flow of the dressing material and the cooling gas during use of the dry core bit. The dressing material and the cooling gas inserted from the insertion hole 2a are rotated by the centrifugal force of the rotation and the guide plate 5. Is efficiently guided to the guide groove 2b formed on the inner peripheral surface of the main body 2 by the inclined surface, and further cut through the guide groove 2b from the introduction path 3a of the joining surface of the segment chip 3 communicating with the guide groove 2b. It will be efficiently supplied to points.

FIG. 4 is a sectional view of a dry core bit 10 according to a second embodiment, in which an auxiliary guide plate 11 having an opening 11a at the center thereof is provided at a certain interval on a side surface of the guide plate 5. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the dressing material or the cooling gas supplied from the insertion hole 2a enters through the opening 11a of the auxiliary guide plate 11 and is guided to the guide groove 2b from between the guide plate 5 and the auxiliary guide plate 11. I will
By thus providing the guide plate in a double manner, the guide plate can be guided to the cutting edge without reducing the flow velocity of the dressing material or the cooling gas.

FIG. 4 is a cross-sectional view of the dry core bit 15 of the third embodiment. In this embodiment, the guide plate 16 is formed in a flat plate shape. The dressing material and the cooling gas can be guided to the guide groove 2b also in the flat shape.

[Test Example] In the 4-inch dry core bit 1 of the first embodiment shown in FIG. 1, a guide groove having a depth of 1.0 mm and a width of 8 mm was formed on a cylindrical base having an outer diameter of 110 mm and a length of 350 mm. The one provided in the article was used. As a comparative example, one having a similar structure without a guide groove and a guide plate was used. The rotation output is 1.5 kw and the spindle speed 700 r. p. m. And 200 × with a compressive strength of 230 kgf / cm ² as a work material
A 500 × 1000 mm piece of reinforced concrete was used.
At the time of drilling, 20 g of alumina powder # 60 was used as a dressing material while constantly supplying compressed air for cooling to the inside.
The perforated capacity in each of the vertical and horizontal orientations was examined.

The results are 40 mm / min in the case of the vertical drilling, 7 mm / min in the comparative example and 7 mm / min in the comparative example, and 32 mm / min in the lateral drilling. However, it was not possible to sufficiently remove it, and it became impossible to pierce the way.

[0021]

As described above, the dry core bit of the present invention has a cylindrical base body having a dressing material or a cooling gas insertion hole at the base end, and a circular base at the tip end of the base body. A plurality of segment chips that are joined in a circumferentially close contact manner, an introduction path that opens inward is provided on the joining surface of the segment chips, and a guide groove that communicates with the introduction path is further provided with a guide groove of the base metal body. A guide plate is formed in the axial direction of the inner peripheral surface, and further has a guide plate for guiding the dressing material or the cooling gas to the guide groove inside the base metal. For this reason, the dressing material and the cooling gas are efficiently supplied to the cutting point, so that good sharpness can be maintained and clogging does not occur. In addition, since it has a simple structure as compared with a conventional helical structure or the like, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1A is a sectional view of a dry core bit according to a first embodiment, and FIG. 1B is a bottom view of the same.

FIG. 2 is an explanatory diagram showing a flow of a dressing material and a cooling gas when the dry core bit shown in FIG. 1 is used.

FIG. 3 is a sectional view of a dry core bit according to a second embodiment.

FIG. 4 is a sectional view of a dry core bit according to a third embodiment.

[Explanation of symbols]

 1,10,15 Dry core bit 2 Base metal body 2b Guide groove 3 Segment chip 3a Introductory path 5 Guide plate 5a Stay 6 Swivel 11 Auxiliary guide plate 11a Opening

Claims (3)

(57) [Scope of request for utility model registration] 1. A cylindrical base metal body having a dressing material or a cooling gas insertion hole at a base end thereof, and a plurality of segment chips joined circumferentially in close contact with a distal end of the base metal main body. An inflow path that opens inward on the joint surface of the segment chip, and a guide groove that communicates with the inflow path is formed in the axial direction of the inner peripheral surface of the base metal body. A dry core bit, wherein a guide plate for guiding the dressing material or the cooling gas to the guide groove is provided inside. 2. The guide groove according to claim 1, wherein the guide groove has a depth of at least twice the abrasive particle diameter of the dressing material injected into the core bit and not more than 50% of the thickness of the base metal body. Dry core bit. 3. The dry core bit according to claim 1, wherein the guide plate is a conical member whose tip is arranged in a base direction.