JPH0479804B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cutting device that enlarges the inner diameter of a prepared hole in advance in order to increase the pull-out strength of the anchor when planting an expansion anchor in concrete. .

BACKGROUND TECHNOLOGY In general, an expansion anchor has a plurality of opening legs formed by providing split grooves extending in the axial direction in the front half of a cylindrical anchor body, and the anchor body is inserted into a pilot hole formed in concrete. In this state, by applying a striking force to the anchor body via a driving pin or a taper plug, the legs are expanded and fixed to the inner wall of the prepared hole.

Problems to be Solved by the Invention However, in the above-mentioned expansion anchor, the opening leg portion is expanded by a component force in the radial direction of the impact force acting in the axial direction of the anchor body. The loss was large and it was difficult to fully expand the leg portions. In particular, in the case of large-diameter expansion anchors that require high pull-out strength (holding force), the amount of expansion of the legs increases in proportion to the diameter, so the predetermined pull-out strength (holding force) is even more difficult to obtain.

For this reason, when anchors have large diameters that require high pull-out strength (holding force), or when high reliability is required in the fastening force even with small diameter anchors, so-called chemical anchors using adhesives are used as the fixing means. Anchor is used.

However, since chemical anchors use adhesive to ensure pull-out strength (holding force), it is necessary to increase the length of embedding in the prepared hole to increase the bonding surface area. Compared to anchors, the pilot hole is deeper and requires more time and effort to drill the pilot hole. In addition, since the adhesive is a two-component mixture type, the mixing and stirring operations are troublesome and operational errors are likely to occur. Furthermore, since the product has not been used for a long time, it is questionable whether the desired pull-out strength (holding force) is maintained due to deterioration of the adhesive and peeling due to external stress during long-term use.

The present invention has been made in view of the above circumstances, and in order to facilitate the expansion of the legs of the aforementioned expansion anchor and ensure the desired pull-out strength (holding force), the present invention has been developed by It is an object of the present invention to provide a device for cutting an enlarged diameter portion in which the spread leg portion is locked.

Means for Solving the Problems In order to achieve the above object, the cutting device of the present invention has a cylindrical main body having a flange at the rear end, and the tip portion of the through hole is formed into a tapered hole with a tapered end. , a plurality of split grooves extending in the axial direction are provided in the front half of the cylindrical body to form a plurality of elastic legs, and a blade is fixedly and protrusively provided on the outer periphery of each elastic leg; A stopper that limits the length of insertion into the pilot hole is fitted in the rear half of the cylindrical body, and is slidably inserted into the through hole of the cylindrical body from the rear end, and has a conical part that engages with the tapered hole at the tip. A rear end portion of the shank protrudes from the cylindrical main body, and a connecting portion for an electric rotating tool is provided at the rear end portion.

Preferably, the stopper is fitted into the cylindrical body so as to be displaceable in the axial direction, so that the insertion length of the cylindrical body into the prepared hole can be adjusted.

Further, by configuring the stopper with a plurality of annular bodies having different thicknesses, the insertion length of the cylindrical body into the pilot hole may be adjusted. In this case, the stopper is molded from plastic material,
It is desirable to have a sound absorption function.

Furthermore, a position detecting collar is provided at the rear end portion of the shank, and when the shank is inserted into the cylindrical body and the elastic legs are expanded to a predetermined position by the conical portion at the tip, the position is detected. It is effective to configure the detection flange to come into contact with the upper end flange of the cylindrical body, so that completion of the opening of the legs can be visually or audibly confirmed.

Operation When the cylindrical body of the cutting device configured as described above is inserted into a pilot hole machined in concrete, the insertion length is limited by the stopper, and the blade at the tip is placed at a predetermined position deep inside the pilot hole. Positioned. Next, when the shank is connected to an electric rotary tool and rotated while applying a striking force, the elastic legs are expanded in the radial direction by the conical portion at the tip of the shank, and due to the frictional contact. The cylindrical body rotates together with the shank. Due to this expanding action and rotational movement, the blade crushes and widens the wall surface of the pilot hole to form a downwardly expanding diameter portion. When the shank is press-fitted until its positioning flange abuts against the cylindrical flange, a predetermined enlarged diameter portion is completed.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. 1 and 2 show a cutting device according to the present invention, in which reference numeral 1 denotes a cylindrical body, which has a flange 2 at the rear end, and a through hole 3 whose tip is a tapered hole. 4.

The front half of the cylindrical body 1 is divided by a plurality of grooves 5 and openings 6 extending in the axial direction, and a plurality of elastic legs 7 (three in the illustrated example) are formed. A blade body 8 made of cemented carbide is fixedly and protrusively provided on the outer periphery of the tip portion of the elastic leg portion 7. In addition,
The blade body 8 may be constructed by fixing a diamond chip to the tip of each elastic leg 7 instead of using cemented carbide. Further, in the latter half of the cylindrical body 1, the inner diameter of the through hole 3 is expanded to form a housing chamber 3a for the return spring 9, and a threaded portion 10 for screwing a stopper 11, which will be described later, is provided on the outer peripheral surface. It is being

Reference numeral 11 denotes a stopper for limiting the insertion length of the cylindrical body 1 into the prepared hole, and is formed into an annular body having a female thread 12 on its inner circumferential surface that screws into the threaded part 10. It can be fixed in position. 14 is a sound absorbing pad attached to the end face of the stopper 11.

As shown in FIG. 7, by combining and loosely mounting a plurality of annular stopper plates 11a to 11c having different thicknesses on the cylindrical body 1, the cylindrical body 1 can be
The insertion length of the pilot hole may be limited. In this case, there is no need to provide the threaded portion 10 on the cylindrical body 1, and the annular stopper plates 11a to
If 11c is molded from a plastic material, the sound absorbing pad 14 will also be unnecessary and the structure can be simplified.

Reference numeral 15 denotes a shank for expanding the elastic leg portion 7, which is slidably inserted into the through hole 3 from the rear end of the cylindrical body 1, and has a conical portion 16 at its tip portion that engages with the tapered hole 4. , a large-diameter shaft 17 is connected to the rear end portion via a connecting pin 18. Then, the protruding portions at both ends of the connecting pin 18 engage with the elongated holes 19 extending in the axial direction provided in the rear end portion of the cylindrical body 1, thereby limiting the movable range of the shank 15 and preventing the return spring from moving. 9 biases the shank 15 to the position shown in FIG. Further, the shaft 17 is formed with a connecting portion 20 for an electric hammer drill, while the cylindrical body 1 is in the original position shown in FIG.
A position detecting flange 21 is provided with a constant distance A between the flange 2 and the flange 2 . The position detecting collar 21 comes into contact with the collar 2 when the shank 15 is press-fitted into the distal end of the cylindrical body 1 and the elastic legs 7 are expanded to a predetermined position by the conical section 16 on the distal end. This makes it possible to confirm the completion of the diameter expansion work visually or by the collision sound produced when the parts come into contact.

FIGS. 3 to 6 show the construction sequence for planting an expansion anchor using the cutting device configured as described above.

First, by adjusting the fixing position of the stopper 11, the insertion length K into the pilot hole 26 previously formed in the concrete 25 is set to the implantation length of the expansion anchor 30 (see FIG. 5) to be implanted in the pilot hole 26. After setting it equal to L, when the cylindrical body 1 is inserted into the pilot hole 26,
The insertion length is limited by the stopper 11, and the blade 8 at the tip is positioned at a predetermined position deep inside the pilot hole 26. Next, an electric hammer drill 35 is interlocked and connected to the connecting portion 20 of the shaft 17.
5 imparts impact force and rotational force to the shank 15. Due to the impact force applied to the shank 15, the conical portion 16 at the tip is press-fitted into the tapered hole 4,
While expanding the elastic legs 7 in the radial direction, the cylindrical body 1 rotates together with the shank 15 due to frictional contact with the wall surface of the tapered hole 4. Due to this expanding action and rotational movement, the blade 8 crushes and widens the wall surface 27 of the prepared hole 26. Then, when the shank 15 is press-fitted into the cylindrical body 1 by applying a striking force to the position where the position detection flange 21 contacts the flange 2 of the cylindrical body 1,
As shown in FIG. 4, the elastic leg portion 7 is expanded to a predetermined position, and a predetermined enlarged diameter portion 28 is formed. At this time, it is easy to complete the diameter expansion work by visually confirming the position of the position detection flange 21 or by auditorily confirming the metallic sound that is generated when the flange 21 comes into contact with the flange 2. can be known.

When the enlarged diameter portion 28 is formed in this way,
After stopping the application of impact force and rotational force to the shank 15 and pulling the shank 15 back to its original position shown in FIG. 3, the cylindrical body 1 is pulled out from the prepared hole 26.

Subsequently, as shown in FIG. 5, the expansion anchor 30 is inserted into the prepared hole 26, and the driving pin 32 is pressurized to press fit into the anchor body 31. As shown in FIG. The open leg portion 33 is expanded in the radial direction and engaged with the enlarged diameter portion 28 .
Due to the engagement of the open leg portion 33 with this enlarged diameter portion 28, the anchor body 3 engages with the wall surface 27 of the pilot hole 26.
1 is securely retained and high pull-out strength (holding force) is obtained. Moreover, due to the presence of the enlarged diameter portion 28, the expansion resistance of the open leg portion 33 is reduced.
The open leg portion 33 is opened by applying a light pressure to the driving pin 32.
can be easily expanded.

In the above embodiment, the pin driving type expansion anchor 30 has been described, but it is of course applicable to other types of expansion anchors. Further, instead of the electric hammer drill 35, the enlarged diameter portion 28 can be formed by press-fitting the shaft 17 while rotating it using an electric drill that only applies rotational force.

Effects of the Invention As explained above, according to the cutting device of the present invention, an enlarged diameter portion can be easily formed at a predetermined position deep inside a pilot hole drilled in concrete. Also,
Completion of the diameter expansion work can be visually or aurally confirmed, which is convenient for work.

When the expansion anchor is implanted in the pilot hole in which the expanded diameter portion is formed as described above, the opening leg portion can be expanded with a small pressure, and by engaging with the expanded diameter portion, Large pull-out strength (holding force) can be obtained. Therefore, even with large diameter expansion anchors,
The legs can be easily and reliably expanded.

[Brief explanation of drawings]

Fig. 1 is a partially vertical front view of the cutting device according to the present invention, Fig. 2 is an end view of the same, Figs. It is a longitudinal front view of a main part showing an example. 1... Cylindrical body, 2... Flange, 3... Through hole,
4...Tapered hole, 5...Split groove, 7...Elastic leg portion, 8...Blade body, 10...Threaded portion, 11...Stopper, 12...Female thread, 13...Set screw, 11
a to 11c...Annular stopper plate, 15...Shank, 16...Conical part, 17...Shaft, 18...Connection pin, 20...Connection part, 21...position detection flange, 25...Concrete , 26... Pilot hole, 27
... Pilot hole wall surface, 28 ... Expanded diameter part, 30 ... Expansion anchor, 33 ... Open leg part.

Claims (1)

[Claims] 1. A through hole 3 in a cylindrical body 1 having a flange 2 at the rear end.
A tapered hole 4 is formed at the tip end of the cylindrical body 1, and a plurality of split grooves 5 extending in the axial direction are provided in the front half of the cylindrical body 1 to form a plurality of elastic legs 7. A blade 8 is fixedly protruded from the outer periphery of the elastic leg 7, a stopper 11 is fitted in the rear half of the cylindrical body 1 to limit the length of insertion into the prepared hole, and the through hole 3 of the cylindrical body 1 A shank 15 is slidably inserted from the rear end thereof, and has a conical portion 16 at its tip portion that engages with the tapered hole 4. A rear end portion of the shank 15 protrudes from the cylindrical body 1, and an electric rotating tool is attached to the rear end portion. A cutting device for enlarging the diameter of the innermost part of a prepared hole of an expansion anchor, characterized in that a connecting portion 20 is provided for the expansion anchor. 2. The cutting device for expanding the diameter of the innermost part of the prepared hole of the expansion anchor according to claim 1, wherein the stopper 11 is fitted so as to be displaceable in the axial direction with respect to the cylindrical main body 1. 3. The cutting device for expanding the diameter of the innermost part of the pilot hole of an expansion anchor according to claim 1, wherein the stopper 11 is composed of a plurality of annular bodies 11a to 11c having different thicknesses. 4 A position detection collar part 21 is provided at the rear end portion of the shank 15, and the shank 15 is press-fitted into the cylindrical body 1, and the conical part 16 at the tip expands the elastic leg part 17 to a predetermined position. Expanding the inner diameter of the pilot hole of the expansion anchor according to claim 1, 2 or 3, wherein the position detecting flange 21 is configured to abut against the flange 2 of the cylindrical body 1 when opened. Scraping device.