JPH0236651Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a drilling device that cuts an enlarged hole portion, that is, an undercut, having a diameter larger than the diameter of the drill hole, 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 cylindrical body 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 you cut the hole wall into the hole to form an enlarged hole in advance,
The pull-out strength of anchor bolts can be significantly increased.

However, using a conventional concrete drilling tool, that is, a normal drilling tool such as a hammer drill, it cannot be expected to form an enlarged diameter hole in the drill hole as described above.

Therefore, the same applicant who created this invention proposed a wedge center which was inserted into the main body at a common axis so that it could rotate together with the main body and be movable relative to the main body under the force of a spring in the axial direction. The blade is moved along an overhanging jaw provided at the tip of the wedge center and is configured to protrude outward from the overhanging jaw, and cuts a pre-drilled hole wall at an appropriate location to form an enlarged diameter hole. A device has been proposed.

For example, when using this device to cut an enlarged diameter section at the bottom of a pre-drilled blind end hole, place the lower end of the wedge center inserted into the hole against the bottom of the hole, rotate the device in this state, and press the main body against the spring. When pushed into the hole against the resistance, the cutting blade, which had been located at the base of the overhanging jaw of the wedge center, will extend outward along the overhanging jaw of the wedge center due to the movement of the main body. Cut the hole wall while moving like this,
Eventually, the overhanging jaw reaches its maximum extension point and protrudes outward from the overhanging jaw, creating an enlarged diameter hole in the hole wall.After this, when the pressing force on the main body is released, the spring action After the cutting blade returns to its normal position at the base of the protruding jaw of the wedge center in the reverse order of the movement described above, the device is withdrawn from the hole.

However, with the enlarged diameter section cutting device having the above configuration, in order to pull out the device from the hole after work, the cutting blade must first return to its normal position at the cutting work position in the hole before it can be pulled out. When cutting an enlarged diameter section at the bottom of a blind end hole, chips generated by cutting the hole wall remain at the bottom of the hole without being removed, and the cutting edge becomes buried in this. After completing diameter expansion cutting, the cutting blade moves over the protruding jaw and returns to its normal position.
In other words, it may impede the return of the cutting blade to the base of the overhanging jaw, worsening the return movement of the cutting blade, and making it difficult to pull out the device from the hole after cutting the enlarged diameter portion.

This idea was developed in consideration of the above points, and after drilling an enlarged diameter hole on the wall of a drilled hole that has been drilled in advance in a material to be drilled, such as concrete, the cutting blade is extended. It is an object of the present invention to provide an enlarged diameter section cutting device which is automatically released from the jaws and freed, and which returns to the normal position to facilitate the removal of the device from the hole, thereby improving workability.

Embodiments of this invention will be described in detail below with reference to the drawings.

In the figure, 1 is a main body having a shank 2 connected to a drive shaft at the upper end, 3 is a wedge center,
The lower end of the wedge center 3 is flattened to form an overhanging jaw 4 that gradually inclines outward from the main body side. Reference numeral 5 denotes a hollow portion provided in the main body 1 with its lower end open, and the wedge center 3 is inserted into the hollow portion 5 with a compression spring 6 interposed therebetween so as to have a common axis. Reference numeral 7 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, and a cutting blade 8 is attached to the tip of the plate pieces, and The cutting blade 8 engages with a guide groove 9 provided in the overhanging jaw 4 to move on the overhanging jaw, and the cutting blade 8 is normally located at the base of the overhanging jaw of the wedge center 3. Due to the relative movement of the wedge center 3 in the axial direction, the wedge center 3 is pulled into the main body hollow part 5 against the spring 6, so that the wedge center 3 moves along the overhanging jaw 4, and the overhanging jaw 4 It is designed to protrude outward.

In the above configuration, this invention forms a notch 10 at the base and tip of the guide groove 9 with which the cutting blade 8 engages, so that the cutting blade 8 can be opened in the rotation direction,
Further, between the main body 1 and the insertion base of the wedge center 3 into the main body 1, there is a notch 1 that moves the cutting blade 8 along the guide groove 9 in the axial direction.
0, the cutting blade 8 moves in and out of the guide groove 9 in the rotational direction, and the cutting blade 8
It is characterized by providing a regulating means 11 that regulates movement in the axial direction in a more open state.

In this embodiment, the regulating means 11 is composed of a keyway 12 provided on the outer circumferential surface of the wedge center 3 and a key 13 that is fixed to the main body 1 and engages with the keyway 12. Due to the relative movement between the wedge center 3 and the wedge center 3, the cutting blade 8 is placed on the guide groove of the wedge center 3 and moves from the base of the guide groove 9 to the notch 10 at the tip. The axial groove portion 12a parallel to the axis corresponds to the position where the cutting edge 8 is released from engagement with the guide groove 9 and is in a free state.
and a circumferential groove portion 12b that connects the axial groove portions 12a in a series in the circumferential direction.

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

As shown in Figure a, when cutting an enlarged diameter hole at the bottom of a pre-drilled blind end hole A, the lower end of the wedge center 3 inserted into the hole is brought into contact with the bottom of the hole.

From this state, when the main body 1 is rotated and pushed into the hole against the spring 6, the cutting blade 8, which had been located at the base of the protruding jaw of the wedge center 3, is moved. While engaged with the guide groove 9 of the overhanging jaw 4, it moves outward along the guide groove 9 to start cutting the hole wall,
As shown in Figure b, the hole wall is cut to form the enlarged diameter hole B until the maximum protrusion point of the protruding jaw 4 is reached.

During this time, the key 13 is inserted into the axial groove 1 of the keyway 12.
Move along 2a. At the same time as the cutting blade 8 reaches the maximum protrusion point of the protruding jaw 4 and reaches the notch provided at the tip of the guide groove 9, the key 13 reaches the connection point with the circumferential groove 12b of the key groove 12. When it reaches the circumferential groove 12b, the rotation of the wedge center 3 stops for a moment, and with only the rotation of the main body 1, the cutting blade 8 is pulled out of the guide groove 9 from the notch 10 and is free as shown in Figure c. It becomes a state. At this time, the cutting blade 8 is caused by the elasticity of the plate 7 to which it is attached.
At the next moment when the key 13 is returned to the axis side and only the main body 1 rotates, that is, the main body 1 rotates 90 degrees with respect to the wedge center 3, the key 13 reaches the connection point with the axial groove 12a of the keyway 12 again. At this point, when the force pressing the main body 1 is released, the biasing force of the spring 6 acts, and the key 13 moves to the axial groove portion 12a of the key groove 12, and the key 13 moves to the base of the guide groove 9. , the key 13 reaches the connection point with the circumferential groove 12b of the keyway 12 and moves to the circumferential groove 12b, and as the main body 1 rotates, the key 13 is extended as shown in Figure e. At the base of the jaw 4, the cutting edge 8 is returned into the guide groove 9 through the notch 10.

That is, in this invention, the cutting blade 8 automatically returns to the normal position before starting work when the cutting of the expanded diameter hole is completed in the hole, and in this way, the device can be pulled out of the hole as it is. It is something that can be done.

As explained above, according to the hole wall diameter expanding device of this invention, when installing anchor bolts in concrete, etc., it is easy to easily attach the diameter enlarged part to the hole wall for the hole previously drilled in the concrete surface. I was able to remove the
It can significantly improve the pull-out strength when installing anchor bolts, and after cutting the enlarged diameter hole inside the hole, the cutting edge automatically prevents the engagement with the overhanging jaw. Once opened, it becomes free and deflates, then returns to its normal position before the start of work, so even if chips remain in the hole after cutting the enlarged diameter part, they will not get in the way. This does not impede the movement of the cutting blade, the return movement of the cutting blade is instantaneous, and the movement of the device is automatically controlled from the start of the work to the end of the work, so there is no need to rely on the operator's intuition. There is no problem at all, and workability can be improved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an embodiment of this invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Figs. 3 a, b, c, d, and e are It is an operation explanatory diagram. DESCRIPTION OF SYMBOLS 1...Main body, 2...Shank, 3...Wedge center, 4...Protruding jaw, 5...Hollow part, 6...Compression spring, 7...Elastic blade plate, 8...Cutting blade, 9... Guide groove, 10... Notch, 11... Regulating means, 1
2...Keyway, 13...Key.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A wedge center is inserted into the main body so that the wedge center rotates together with the main body and the shaft is movable relative to the main body under the bias of a spring in the axial direction, and the wedge center is attached to the main body. In a diameter expanding hole cutting device that moves a blade along an overhanging jaw provided at the tip of a wedge center so that it protrudes outward from the overhanging jaw, and inserts it into a pre-drilled hole to cut the hole wall. , the overhanging jaw of the wedge center is formed into a flat shape, and a guide groove for the cutting blade is provided in the overhanging jaw, and a notch is provided at the base and tip of the guide groove so that the cutting blade can be opened in the rotation direction. On the sliding peripheral surface of the main body and wedge center, movement in the axial direction to move the cutting blade along the guide groove, and rotation to move the cutting blade in and out of the guide groove through the notch of the guide groove. movement in the direction,
Furthermore, a diameter expansion hole cutting device is provided, which is provided with a regulating means for regulating the movement in the axial direction when the cutting blade returns. (2) The diameter enlarged hole cutting device according to claim 1, wherein the regulating means is constituted by a key and a keyway on the sliding peripheral surfaces of the main body and the wedge center.