JP2986352B2 - Removal method and jig for driving anchor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a jig for removing a driven anchor attached to a concrete structure.

[0002]

2. Description of the Related Art Temporary scaffolds are installed to repair the outer surface of concrete structures such as bridge girders. In order to secure such scaffolds, generally a drive-in anchor is attached to concrete, and an eyebolt is screwed into the anchor and a chain is attached. Suspends the scaffold. When the repair work is completed, the temporary scaffolding will also be removed, but the removal of the anchors driven into the concrete structure is often left unnecessarily. However, the anchor that has been left unattended impairs the appearance of the concrete structure due to rust, and the anchor is corroded and expanded in volume, causing cracks in the concrete and reducing its strength. Therefore, the anchor must be removed.

[0003] In the driving type anchor, a frusto-conical head is inserted in advance into a cylindrical hole for driving an anchor in a concrete structure, and when the anchor is driven in, the hollow end of the anchor is forcibly expanded by the head. It is firmly fixed to concrete by frictional force on the uneven surface on the outside of the anchor. Conventionally, when removing an anchor, concrete around the anchor was broken and taken out, and the portion was restored to its original shape using mortar or the like. In such a restoration method, the concrete around the anchor must be destroyed in a wide area, which requires not only a great deal of labor including the restoration of the original shape but also damage to the concrete structure. there were.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems and to provide a method and a method for removing a driven anchor in which the anchor can be easily pulled out without breaking concrete around the anchor. It is intended to provide tools.

[0005]

SUMMARY OF THE INVENTION The present invention comprises inserting a frusto-conical head into a cylindrical hole for anchoring a concrete structure, and then having a hollow having a diameter greater than the diameter of the head tip. And, by driving an anchor having an uneven portion with a saw-tooth cross section on the outer periphery, the tip of the anchor is expanded with the head to remove the driven anchor fixed by the wedge effect, the base of the jig for anchor removal is By fixing the jig to the tip of the head via the hollow portion of the anchor, the tip of the jig is removed from the head by the reaction force received by the jig, and the wedge effect is removed. A method of removing a drive-in type anchor, wherein the anchor is removed and the anchor together with the jig is pulled out from a hole in a concrete structure.

Further, the present invention provides a jig for expanding a tip of an anchor with a frusto-conical head to remove a hammered anchor fixed to a concrete structure by a wedge effect, wherein the anchor is provided around a base of the jig. An external thread portion for screwing the head is provided, and a projecting end portion of the jig has a sufficient length to press the head through a hollow portion of the anchor, and is a jig for removing a drive-in type anchor.
In this jig, the male thread of the base of the jig is screwed into the female thread of the hollow part of the anchor, and the jig is pushed forward. The protrusion of the jig is pressed against the frusto-conical head, and the anchor is pulled out. It is to take out the anchor from.

Another anchor removing jig according to the present invention comprises a main body and an adapter, and has a male thread portion which is screwed with a hollow female portion of the adapter around a base portion of the main body.
A driving-type anchor removal jig provided with a male thread portion which is screwed into a hollow internal thread portion of the anchor around the adapter. This jig consists of a main body and an adapter, and can be screwed between the external thread of the main body and the screw part to be provided in the hollow part of the adapter that constitutes the base of the jig. Is screwed into the female thread of the hollow part of the anchor and fixed, then the main body is advanced along the thread, the protrusion of the main body is pressed against the head, the anchor is pulled out, and the anchor is taken out of the concrete structure. It is.

[0008]

The present inventors are studying a method for removing a drive-in anchor without destroying the concrete around the anchor. And pulling the anchor from the head, focusing on the fact that it is firmly fixed to the concrete by frictional force,
The present inventors have found that the wedge effect of the head can be eliminated and the anchor can be easily pulled out without damaging the concrete structure, and the present invention has been completed.

FIGS. 1 and 2 are cross-sectional views for explaining an example of a method of removing a driving anchor and a jig according to the present invention. In the figure, 1 is an anchor, 2 is a frusto-conical head, 3 is a hole in a concrete structure, 4 is a jig for removing the anchor, a handle 4c at the head and a rod-shaped projection 4b at the tip, It is composed of a male thread part 4a that is screwed with the female thread part 1a of the anchor 1.

As shown in FIG. 1, the anchor 1 is driven into a hole 3 of a concrete structure, the tip of which is pushed and expanded by a head 2, and the uneven surface 1b provided on the outer surface of the tip of the anchor 1 has an uneven surface 1b. It is firmly fixed to the wall surface of the hole 3 by a frictional force. To remove the anchor 1, the external thread 4 a of the jig 4 is screwed into the internal thread 1 a of the anchor 1 to advance the jig 4, and as shown in FIG.
Abuts the head 2 on the head 2 so that the hole 3
The head 2 is pressed against the bottom of the anchor 1 and the anchor 1 is pulled out of the head 2 under the reaction force. As a result, the tip of the anchor 1 pushed and expanded by the head 2 becomes concave and separates from the wall surface of the hole 3 of the concrete structure, so that the frictional force between the wall surface and the uneven surface provided on the outer surface of the anchor 1 tip is reduced. Lost, the anchor 1 can be easily removed from the hole 3 by the jig 4.

FIGS. 3 and 4 are cross-sectional views for explaining another example of the method of removing the driving anchor and the jig of the present invention. The jig 5 used for removing the anchor adopts a structure in which the jig 5 is screwed with the female thread portion 1a of the anchor 1 via the adapter 6. The jig 5 has a handle 5c on the head.
And a bar-shaped projection 5b at the tip, and a male thread 5a screwed into the female thread 6a of the through hole of the adapter 6. A male thread 6b is formed around the adapter 6, and the anchor 1
The female screw portion 1a is screwed.

The situation in which the anchor 1 is fixed to the hole 3 of the concrete structure is the same as that shown in FIG. 1, but when removing the anchor, the external thread 6b of the adapter 6 is screwed with the internal thread 1a of the anchor 1. After fixing, the jig 5 is rotated to advance the jig 5 along the female screw portion 6a of the adapter 6, and as shown in FIG. , The head 2 is pressed against the bottom of the hole 3 of the concrete structure, and the anchor 1 is pulled out from the head 2 under the reaction force. As a result, the tip of the anchor 1 pushed and expanded by the head 2 is depressed and separates from the wall surface of the hole 3 of the concrete structure. Is lost, and the anchor 1 can be easily removed from the hole 3 by the jig 5.

When the projection 5b of the jig 5 comes into contact with the head 2 and the anchor 1 is pulled out from the head 2, the anchor 1 may be idled together with the jig 5 and the adapter 6, so that the adapter 6 is pressed. For this purpose, a handle 7 or the like may be attached to the upper part of the adapter 6. The handle 7 also facilitates the screwing of the adapter 6 to the anchor 1.

[0014]

EXAMPLE A hole was drilled in a concrete specimen with a concrete drill, and hawks and cut anchors M12 and M16 were drilled.
[KFC Co., Ltd.] was driven in by ordinary means, and it was confirmed that the anchor was firmly fixed to the concrete. Then, the anchor was fixed using the jig shown in FIGS. 1 and 3. A removal experiment was performed.

To remove the M12 anchor, as shown in FIG. 1, a jig having an M12 female thread with a length of 30 mm on the base and a projection with an outer diameter of 8 mm and a length of 40 mm is provided at the tip. used. Insert a T-shaped jig into the anchor, screw it into the female thread of the anchor, rotate the handle and press the tip of the jig against the head. After the frictional force between the uneven surface of the part and the wall surface of the concrete hole was lost, the jig and the anchor could be easily pulled out without damaging the surrounding concrete at all. Also, the head at the bottom of the hole in the concrete could be taken out together with the magnet bar by inserting a magnet bar into the hole, attracting the magnet.

For removing the M16 anchor, a jig provided with an adapter is used as shown in FIG. The adapter has an M16 external thread having a length of about 30 mm on the outer periphery and an M10 internal thread at the center of the shaft. The adapter is screwed into the through hole of the M16 anchor, the male thread of the jig is screwed into the female thread of the adapter M10, and the T-shaped handle is rotated to attach the jig to the female thread of the adapter M10. The jig's tip projection against the head at the bottom of the concrete hole, and separate the anchor from the head by reaction force, losing the frictional force between the uneven surface of the anchor and the wall surface of the concrete hole. After that, the jig was easily pulled out together with the anchor, and the surrounding concrete was not damaged at all. Also, the head could be easily taken out with a magnet bar.

[0017]

According to the present invention, by adopting the above structure, a driving anchor firmly fixed to a hole of a concrete structure by a wedge effect of a head can be easily applied without breaking the concrete structure. Can be removed at any time, eliminating the need for restoration work on damaged concrete.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a method of pulling out a driving type anchor and a jig of the present invention, and is a view for explaining a state in which the jig is fixed to a through hole of the anchor.

FIG. 2 is a view for explaining a state where an anchor is separated from a head by the jig of FIG. 1;

FIG. 3 shows another pull-out of the drive-in anchor of the present invention.
It is sectional drawing for demonstrating two methods and a jig, and is a figure for demonstrating the state which attaches a jig and an adapter to the through-hole of an anchor.

FIG. 4 is a view for explaining a state where an anchor is separated from a head by the jig of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Anchor, 1a Female thread part of anchor, 1b Uneven surface of anchor tip, 2 heads, hole of concrete structure, 4 jig, 4a screw part of jig, 4b protrusion of jig, 4c handle, 5 Jig with adapter, 5
a threaded part of the jig body, 5b projection part of the jig body, 5
c Handle, 6 adapters, 6a adapter thread, 6b female thread of adapter through hole, 7 handle.

Claims (3)

(57) [Claims] 1. Inserting a frusto-conical head into a cylindrical hole for driving an anchor in a concrete structure, and then having a hollow having an inside diameter slightly larger than the diameter of the head tip,
And, by driving an anchor having irregularities on its outer surface to expand the tip of the anchor with the head and remove the driven anchor fixed by the wedge effect, the base of the jig for anchor removal is screwed into the anchor. By pressing the tip projection of the jig against the head via the hollow portion of the anchor, the tip of the anchor is removed from the head by the reaction force received by the jig, the wedge effect is eliminated, and the jig is removed. A method for removing a drive-in type anchor, wherein the anchor is pulled out from a hole in a concrete structure. 2. A jig for expanding a tip of an anchor with a frusto-conical head to remove a driven anchor fixed to a concrete structure by a wedge effect, and screwing the anchor around a base of the jig. A jig for removing the drive-in type anchor, wherein a male screw portion is provided, and a tip projection of the jig has a length sufficient to press the head through a hollow portion of the anchor. 3. A jig for removing an anchor is composed of a main body and an adapter, and a male screw portion is provided around the base of the main body to be screwed with a hollow female screw portion of the adapter, and the anchor of the anchor is provided around the adapter. 3. The jig for removing a drive-in type anchor according to claim 2, wherein a male thread portion screwed into the hollow female portion is provided.