JPH07100245B2 - Core drill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a core drill used for making a relatively large hole in a concrete material or the like.

[Prior art]

Conventionally, a wide variety of core drills have been developed and marketed for drilling large-diameter holes, and these core drills have a drilling blade adapted to the material of the object to be drilled.

By the way, in a core drill for a solidified concrete material, a perforating blade made of a cemented carbide tip is provided on the lower end opening peripheral edge of a cylindrical core body, and the side surfaces of the perforating blade are on both inner and outer surfaces of the core body. On the other hand, it has a thick shape with a slight protrusion.

As described above, when a through hole is drilled in a concrete material using a core drill provided with protruding drilling blades on both the inner and outer surfaces of the core body, after the hole is drilled, the core body is hollowed into a cylindrical shape. The cut lump remains, but when the cut lump is pulled out to the lower end opening side of the core body, the punching blade portion projecting to the inner surface side of the core interferes and makes it difficult to pull out.

Therefore, in order to facilitate the extraction of the cutting mass from the core body, the core body is configured separately from the top plate that is integrated with the shank, and after the hole is drilled, the two are separated to separate the cutting mass from the core body. A core drill has been proposed which is drawn out from the upper end opening side.

[Problems to be Solved by the Invention]

However, in the conventional core drill in which the top plate and the core body are separate bodies, since a screw structure or the like is adopted for connecting the top plate and the core body, it is troublesome to connect and separate the both, and workability is poor, Further, there is a problem that the screw structure portion is worn out by repeated use, which adversely affects the connection between the two.

The present invention has been made in view of the above points, and is easy to connect and separate the top plate and the core body for convenient handling. An object is to provide a core drill with excellent workability.

[Means for Solving the Problems]

The gist of the present invention for achieving the above object is to include a top plate having a shank at the center of the upper surface and a cylindrical core body provided with a perforating blade at the lower end opening peripheral edge. The body mounting portion is formed, and the top plate is provided with a plurality of holding holes that are inclined outward from the top surface of the top plate toward the peripheral surface of the core body mounting portion and are inclined rearward in the rotational direction. The core body mounting portion is opened at the peripheral surface of the body mounting portion, and the coupling ball urged by a spring is fitted and held in the holding hole to cause a part of the coupling ball to project to the peripheral surface of the core body mounting portion. An engaging hole is formed in the upper end opening of the core body into which the coupling ball protruding on the peripheral surface of the core body attaching portion is engaged and disengaged. The core drill is characterized in that a slanted edge portion that is slanted upward is formed on the core drill.

[Action]

When the core body mounting part of the top board is inserted into the upper end opening of the core body, the upper end opening edge of the core body slides upward against the connecting ball to push the connecting ball into the holding hole, and the connecting ball engages. When it coincides with the fitting hole, the top plate and the core body are joined by projectingly engaging with the engagement hole.

When the top plate and the core body are connected to each other and a force is applied to separate the top plate and the core body from each other in the axial direction, the upper edge of the engaging hole is pressed against the connecting ball and the connecting ball moves downward from the holding hole. A force acts in the direction of pulling out to prevent the top plate from separating from the core body.

When rotating in the drilling direction during drilling work, the front edge of the engaging hole is pressed against the joining ball and a force in the direction of pulling out the joining ball backward in the rotational direction acts, and the joining relationship between the top plate and the core body is changed. The hole is drilled by stabilizing and transmitting the rotational torque from the top side to the core body.

When the top plate and the core body are relatively rotated in a direction opposite to the direction at the time of making the hole, the inclined edge portion of the engaging hole slides laterally against the connecting ball to push the connecting ball into the holding hole, When the top plate and the core body are separated from each other in the axial direction when the connecting ball is pulled out from the engaging hole, the two are separated.

〔Example〕

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 is an exploded perspective view of a core drill of the present invention, FIG. 2 is a front view of a top plate, and FIG. 3 is a plan view of the top plate with a part thereof removed.

In the figure, reference numeral 1 is a top plate having a shank 2 in the center of the upper surface. Reference numeral 3 denotes a core body mounting portion formed on the top board 1, and has a stopper collar 4 on the upper portion.

Reference numeral 5 denotes a plurality of holding holes provided on the top board 1.
Is inclined outward from the top surface of the top board 1 toward the peripheral surface of the core body mounting portion 3 and is also inclined rearward in the rotational direction to form an opening 6 in the peripheral surface of the core body mounting portion 3.
Has a slightly narrowed structure in order to prevent extraction of the coupling balls described later.

Reference numeral 7 denotes a coupling ball that is fitted and held in the holding hole 5, and a spring 8 biases the coupling ball 7 toward the opening 6 in the holding hole 5 so that a part of the coupling ball 7 protrudes from the opening 6 in a retractable manner. There is.

Reference numeral 9 denotes a cylindrical core body having a drilling blade 10 provided on the periphery of the lower end opening. The drilling blade 10 in the embodiment is made of a cemented carbide chip and adapted for drilling concrete or the like. The side surface of the blade (10) is slightly projected to both the inside and outside of the core.

Reference numeral 11 denotes an engagement hole formed in the upper end opening of the core body 9 corresponding to the coupling ball 7, and the coupling ball 7 is engaged with and disengaged from the peripheral surface of the core body mounting portion 3 and projects from the opening 6. An inclined edge portion 11a which is adapted to the size of the coupling ball 7 and has a slightly laterally long hole shape is formed at the lower edge thereof so as to be inclined upward toward the rear in the rotational direction.

In the figure, 12 is a cover plate that is fixed to the top surface of the top plate 1 in a superposed manner, and 13 is a pressing piece that is inserted into the holding hole 5 and presses and holds the spring 8 in a compressed state.

In the above configuration, when the core body attachment portion 3 is fitted into the upper end opening of the core body 9 to connect the top board 1 and the core body 9,
Since the holding hole 5 inclines outward from the upper surface of the top board 1 toward the peripheral surface of the core body mounting portion 3, the upper end opening edge of the core body 9 has a fourth position on the coupling ball 7 protruding to the peripheral surface of the core body mounting portion 3. As shown by the arrow in the figure, the connecting ball 7 is pushed upward into the holding hole 5 by sliding contact, and when the connecting ball 7 is aligned with the engaging hole 11, the connecting ball 7 is projectingly engaged with the engaging hole 11, and the top board And the core body are connected.

When the force for separating the top board 1 and the core body 9 from each other in the axial direction is applied in the state where the top board 1 and the core body 9 are coupled, the upper edge portion of the engagement hole 11 is pressed against the coupling ball 7. As shown by the arrow in FIG. 5, a force in the direction of pulling out the connecting ball 7 downward acts and the connecting ball 7 does not move, and the top board 1 and the core body 9 are not moved.
Is prevented from separating.

When the top board 1 and the core body 9 are combined and rotated in the drilling direction, the holding hole 5 inclines backward from the top surface of the top board 1 in the rotational direction, so that the connecting ball 7 has a front edge of the engagement hole 11. As shown by the arrow in FIG. 6, the portions are pressed against each other, and a force in the direction of pulling out the connecting ball 7 backward (laterally) in the rotation direction does not move, and the top board 1 and the core body 9 are engaged with each other. Is stabilized and drilling is performed.

When the core body 9 is relatively rotated with respect to the top board 1 in a direction opposite to the above-described hole rotation direction, the coupling ball 7 has an engagement hole.
As the slanted edge portion 11a of 11 is slid sideways to push the coupling ball 7 into the holding hole 5, as shown by the arrow in FIG.
The top board 1 and the core body 9 can be separated from each other.

〔The invention's effect〕

The core drill of the present invention configured as described above has the following effects.

(1) The top board and the core body are connected to each other via a connecting ball. The connection is made by fitting the core body mounting portion of the top board into the upper end opening of the core body and engaging the core body with an engaging hole. Since it suffices that the connecting balls on the top plate side are engaged in a protruding manner, the operation can be easily performed with one touch and the workability is improved.

(2) The top plate and the core body should be separated from each other only by rotating the top plate and the core body slightly relative to each other to release the engagement relationship of the coupling ball with the engagement hole. Since it cannot be pulled apart, the top panel and the core body are not inadvertently separated, which facilitates handling.

(3) Since only a plurality of holes (engagement holes) are bored in the upper end opening of the core body, the cutting mass remaining inside the core body after the boring work is removed from the upper end opening of the core body. When removing from the core, there is no obstruction in the core, and the cut mass can be easily taken out. In addition, wear and the like do not occur even after repeated use, and the service life is extended.

(4) If the joint between the top board and the core is standardized,
Since multiple types of core bodies with different types of punching blades can be shared for one top plate, it is possible to use the core body with different types of drilled objects and core bodies when the drilling blade is worn out. Convenient for replacement, economical and versatile.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a core drill of the present invention, FIG. 2 is a front view of a top board, and FIG. 3 is a plan view with a part of the top board cut away.
FIG. 4 is a vertical cross-sectional view of an essential part for explaining the joining process of the top board and the core body, and FIG. 5 is a vertical cross-sectional view of an essential part for explaining the joined state of the top board and the core body. FIG. 6 is a cross-sectional view of an essential part for explaining the drilling, and FIG. 7 is a front view of the essential part for explaining the separation of the top plate and the core body. 1 ... top board, 2 ... shank, 3 ... core body mounting part,
4 …… Stopper collar, 5 …… Holding hole, 6 …… Opening, 7
...... Coupling balls, 8 ...... Springs, 9 ...... Core bodies, 10 ......
Punching blade, 11 ... Engagement hole, 11a ... Inclined edge, 12 ... Cover plate, 13 ... Pushing piece.

Claims (1)

[Claims] 1. A top board having a shank at the center of the upper surface and a cylindrical core body provided with a perforation blade at the peripheral edge of the lower end opening, and a core body mounting portion is formed on the top board. , A plurality of holding holes that are inclined outward from the top surface of the top surface toward the peripheral surface of the core body mounting portion and are inclined rearward in the rotation direction are opened in the peripheral surface of the core body mounting portion, In, the fitting balls held by the spring are fitted and held to cause a part of the fitting balls to project to the peripheral surface of the core body mounting portion, and the core body mounting portion is fitted into the upper end opening portion of the core body, An engaging hole is formed on the peripheral surface of the core body attaching portion for engaging and disengaging the connecting balls, and an inclined edge portion that is inclined upward toward the rear in the rotation direction is formed at the lower edge of the engaging hole. A featured core drill.