JPH0411766Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an enlarged-diameter hole cutting device for cutting an enlarged-diameter hole portion having a diameter larger than the diameter of the drill hole, that is, an undercut, at a proper location on the hole wall of a pre-drilled hole.

When installing an anchor bolt in solidifying concrete, a blind end hole of a specified depth is drilled in the concrete, the base of the anchor bolt is inserted into this hole, and a slit is machined in the axial direction. Techniques such as enlarging the blind end cylinder and creating frictional resistance between it and the hole wall are adopted.

The pull-out strength of an anchor bolt planted in a concrete surface in this way is largely influenced by the bonding strength between the blind end cylinder and the hole wall. If an enlarged diameter hole is formed in advance by carving the hole wall within the hole, the pull-out strength of the anchor bolt can be significantly increased.

However, conventional drilling tools for concrete,
That is, a hole drilled using a normal drilling tool such as a hammer drill has the same diameter at each part, and it is not possible to drill the enlarged diameter part as described above.

This idea was created in view of the above points, and it is possible to easily drill an enlarged diameter hole at any hole wall position in a pre-drilled hole in a solidified material such as concrete. It is an object of the present invention to provide a convenient diameter expanding hole drilling device.

Hereinafter, embodiments of this invention will be described in detail with reference to the drawings.

In Fig. 1 and Fig. 2, 1 is a main body having a shank 2 connected to a drive shaft at the upper end, 3 is a hollow part provided in the main body 1 with its lower end opened, and 4 is compressed into this hollow part 3. A wedge center 4 is inserted with a spring 5 interposed therebetween, and a protruding jaw 6 is formed at the lower end of the wedge center 4 so as to gradually incline and protrude outward from the main body side. Reference numeral 7 denotes a stop ring loosely inserted around the outer periphery of the main body, and this stop ring 7 is connected to the upper part of the wedge center inside the main body by a rod pin 9 through an elongated hole 8 provided in the wall of the hollow part of the main body in the axial direction. Reference numeral 10 denotes a pair of plate pieces having appropriate elasticity that are formed facing each other by cutting the main body 1 at the lower part of the main body.A cutting blade 11 is provided at the lower end of the plate piece 10. It is made to engage with an inclined guide groove 12 provided in and can be extended outward from the main body by moving downward.

However, the cutting edge 11 is normally located at the wedge center 4.
It is located at the base of the overhanging jaw, and the wedge center 4
As the cutting blade 11 moves in the direction of being drawn into the main body hollow portion 3 against the spring 5, the cutting blade 11 moves on the overhanging jaw and projects outward from the overhanging jaw.

Next, the manner of use of the device of this invention having the above configuration will be explained with reference to the drawings.

(1) Figures 3a, b, and c show the case where an enlarged diameter portion is cut at the bottom of a blind end hole A that has been previously drilled.

As shown in Figure a, the lower end of the wedge center 4 inserted into the hole A is brought into contact with the bottom of the hole, and from this state the main body 1 is rotated against the spring 5.
When the wedge is pushed into the hole, the cutting blade 11, which had been located at the base of the overhanging jaw of the wedge center 4, moves onto the overhanging jaw 6 and moves outward from the overhanging jaw, as shown in Figure b. The enlarged diameter hole portion B is formed by cutting the hole wall to enlarge the diameter to the protruding position.

After this, when the force pushing the main body 1 into the hole is released, the cutting blade 11 naturally returns to its normal position at the base of the overhanging jaw due to the elasticity of the spring 5 and the plate piece 10, as shown in Figure c, and remains as it is. It is pulled out through hole A.

In addition, when cutting the enlarged diameter hole B at the bottom of the hole described above, the hole depth is such that the distance from the hole opening surface to the stop ring 7 is equal to the overhanging jaw of the cutting blade 11 with the wedge center tip touching the hole bottom. This can be carried out if the movement distance is greater than the above movement distance.

(2) Figures 4a, b, and c show the case where an enlarged diameter hole is cut in the middle part of a deep hole c that has been previously drilled.

As shown in Figure a, the lower part of the main body is inserted into the hole A and the stop ring 7 is brought into contact with the opening surface of the hole.

However, the wedge center 4 inserted into the hole is in a floating state in the hole, and from this state the main body 1
When the body 1, that is, the stop ring 7, is pressed against the hole opening surface against the spring 5 while being rotated, the cutting blade 11 located at the base of the protruding jaw of the wedge center 4 is moved by the movement of the body 1. Therefore, the wedge center 4 is moved over the overhanging jaw 6, and the diameter of the hole wall is expanded to a position where the overhanging jaw protrudes outward, as shown in FIG.

After this, when the force pressing the stop ring 7 against the hole opening surface is released, the cutting edge 1 is removed as shown in Figure c.
1 naturally returns to its normal position at the base of the protruding jaw due to the elasticity of the spring 5 and the plate piece 10, and is pulled out from the hole A as it is.

Incidentally, the above-mentioned cutting of the enlarged diameter hole B in the middle part of the hole wall can be carried out at a hole wall position at a distance from the lower surface of the stop ring 7 to the overhanging jaw 6 of the wedge center 4, regardless of the hole depth.

FIG. 5 shows a second embodiment, in which a spacer 13 is detachably attached to a stop ring 7, and the stop ring 7 and the hole can be attached to each other as necessary when drilling a deep hole to enlarge the diameter of the hole. By inserting a spacer 13 of an appropriate height between the opening surface and the opening surface, the position at which the enlarged diameter hole is cut can be changed.

Note that when working by replacing a plurality of spacers 13 of different heights for the same hole, as shown in FIG.
It is also possible to delete.

14 in the figure is the stop ring 7 and the spacer 13
A ball bearing is inserted in the connecting part of the machine, which allows for smooth rotation of the device and improves work efficiency.

FIG. 7 shows a third embodiment, in which a balance adjustment spring 15 is interposed between the main body 1 and the stop ring 7 on the upper outer periphery of the main body 1, and acts in a direction to increase the spring pressure in the hollow part of the main body. If the object to be drilled is soft due to its material properties, the adjustment spring 15 balances the weight applied to the main body 1 to facilitate the work.

As explained above, according to the diameter expansion hole drilling device of this invention, when installing an anchor bolt in concrete, etc., it is possible to easily expand the diameter of the hole drilled into the concrete surface into the hole wall. It is possible to cut the diameter portion, and also to cut the enlarged diameter hole portion by changing the position in steps with respect to the hole wall, thereby significantly increasing the pull-out strength of the anchor bolt.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an embodiment of this invention, Fig. 2 is a side view of a portion of the same essential parts, Figs. 3 a, b, c, and 4 a, b, c. is an explanatory diagram of the operation, FIG. 5 is a front view with a part removed showing the second embodiment, FIG. 6 is a cross-sectional view of the machined hole shape, and FIG. 7 is a partially cut-out view showing the third embodiment. It is a front view. 1...Main body, 2...Shank, 3...Hollow part,
4... Wedge center, 5... Compression spring, 6...
Overhanging jaw, 7...Stop spring, 8...Long hole, 9
... Pin, 10 ... Plate piece, 11 ... Cutting blade, 12 ...
...Guide groove, 13...Spacer, 14...Ball bearing, 15...Balance adjustment spring.

Claims (1)

[Scope of utility model registration request] A wedge center is inserted into a hollow part provided in the main body so that it can rotate together with the main body and can move in the axial direction under the bias of a spring, and the wedge center is integrally connected to a stop ring that is loosely inserted around the outer periphery of the main body. A cutting edge is provided at the lower end of a pair of plate pieces having appropriate elasticity that are formed facing each other by cutting the main body at the lower part,
The cutting edge is configured to engage with an inclined guide groove of an overhanging jaw provided at the lower end of the wedge center, and to project outward from the overhanging jaw by moving downward along the inclined guide groove. Diameter expansion hole cutting device.