JPH0110173Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Industrial application field) This invention is a method of cutting a hole with an enlarged diameter larger than the diameter of the pilot hole, that is, an undercut, at a suitable location on the hole wall of a pilot hole that has been previously drilled. It is related to the device.

(Prior art) To plant an anchor bolt in solidifying concrete, a blind end hole of a predetermined depth is drilled in the concrete, the base of the anchor bolt is inserted into this hole, and a cut groove ( There is a method of enlarging a blind end cylindrical body with a slit (slit) to create frictional resistance between it and the hole wall.

The pull-out strength of an anchor bolt planted in the concrete surface in this way is largely influenced by the bonding strength between the blind end cylinder and the hole wall, but the By cutting the hole wall to form an enlarged diameter hole in advance, the pull-out strength of the anchor bolt can be significantly increased. However, using a conventional drilling tool for concrete, that is, a normal drilling device such as a hammer drill, it cannot be expected to form an enlarged diameter hole portion in a drill hole as described above.

Therefore, by the same applicant as this invention, a wedge center 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 in the axial direction under the bias of a spring, and a cutting blade attached to the main body. An apparatus has been proposed in which the wedge is moved along an overhanging jaw provided at the tip of a wedge center so that the overhanging jaw projects outward, and the prepared hole is cut at an appropriate position to form an enlarged diameter hole. ing.
(For example, Utility Model Application No. 59-45306) When cutting an enlarged diameter part at the bottom of a blind-end pilot hole using this device, place the lower end of the wedge center inserted into the hole against the bottom of the hole, and hold it in this state. When the device is rotated and the main body is pushed into the hole against the spring, the cutting blade, which was previously located at the base of the overhanging jaw of the wedge center, becomes tensioned by the movement of the main body. The hole wall is cut while moving outward along the protruding jaw, and eventually reaches the maximum protruding point of the protruding jaw and protrudes outward from the protruding jaw to form an enlarged diameter hole in the hole wall. After this, when the pressing force on the main body is released, the cutting blade returns to its normal position at the base of the overhanging jaw of the wedge center in the reverse order of the movement described above due to the action of the spring.
The device is to be withdrawn through the hole.

(Problem to be solved by the invention) By the way, with the enlarged diameter part cutting device having the above configuration, in order to pull out the device from the hole after work, the cutting blade must be moved to the normal position (the overhanging jaw) at the cutting work position in the hole. It cannot be pulled out until it returns to the base (base), and when cutting an enlarged diameter part at the bottom of the blind end hole, chips generated by cutting the hole wall may remain without being removed. However, the cutting blade becomes buried in this and prevents it from returning to its normal position at the base of the overhanging jaw, which prevents the returning movement of the cutting blade and makes it difficult to pull out the device from the hole. During operation, the cutting blade may get stuck in the guide groove and become impossible to pull out.

This idea was developed in consideration of the points mentioned above, and the cutting blade overhangs the hole after cutting the enlarged diameter hole on the wall of the pilot hole previously drilled in the material to be drilled, such as concrete. When the device is returned to its normal position by spring force along the guide groove of the jaw, even if the cutting blade gets stuck in the guide groove and cannot be returned, the device can be reliably pulled out with a simple operation. It is an object of the present invention to provide an enlarged diameter section cutting device equipped with a drawing mechanism.

(Means for Solving the Problems) The structure of this invention is that a wedge center is inserted into the main body so that it rotates together with the main body and the axis and is movable relative to the main body under the bias of a spring in the axial direction. Expansion hole machining involves moving the attached cutting blade along the guide groove of the overhanging jaw provided at the tip of the wedge center, protruding outward from the overhanging jaw, and inserting it into the pilot hole to cut the hole wall. In the device, an engaging body connected to the wedge center via a pin is disposed so as to be movable in the axial direction with respect to the main body, and the upper end of the push member that can be connected to the engaging body is attached to a nut screwed onto the upper outer circumferential wall of the main body. fixed,
The gist is that by tightening the nut, the engaging body is pushed down via a pushing member, and the main body and the wedge center are separated from each other.

(Function) The device of this invention cuts the enlarged diameter hole part on the wall of the pilot hole previously drilled in the object to be drilled, and then the cutting blade bites into the guide groove of the overhanging jaw and presses the main body. If the cutting blade does not automatically return to its normal position at the base even after you release the force, tighten the nut against the main body and push down the engaging body with the push member to make the main body relative to the wedge center. When pulled up, the cutting edge is forcibly moved toward the base along the guide groove.

In this way, the device can be pulled out of the hole with the cutting edge returned to the base of the guide groove.

(Example) Hereinafter, an example of this invention will be described in detail with reference to the drawings.

In the figure, 1 is a main body, into which a shank 2 connected to a drive shaft (not shown) is inserted into a central hole formed at its upper end, and a shear pin 3 that passes through the main body 1 and shank 2 laterally in series connects the two. are integrally rotatably coupled. Reference numeral 4 designates a wedge center, and the lower end of the wedge center 4 forms an overhanging jaw 5 that extends downwardly and gradually outwardly.

6 is a hollow part provided in the main body 1 with its lower end opened;
The wedge center 4 is inserted into the hollow portion 6 with a common axis. 7 is at the bottom of the main body,
A cutting blade 8 is attached to the tip of each plate piece 7, and the inner surface of the cutting blade 8 is provided on the overhanging jaw 5. The cutting blade 8 is engaged with a guide groove 9 to move on the overhanging jaw 5, and the cutting blade 8 is normally located at the base of the overhanging jaw 5. Reference numeral 10 denotes a pair of vertically elongated holes formed opposite to each other in the circumferential wall of the hollow portion 6 of the main body 1. A pin 11 passing through the upper end of the wedge center 4 is projected outward from the vertically elongated hole 10, and both ends of the pin 11 is fixed to a cylindrical engaging body 12 having an open upper end and fitted onto the outer periphery of the main body 1 so as to be movable in the axial direction of the main body 1. Further, a cylindrical receiving seat 13 which faces the engaging body 12 and has a slightly smaller diameter than the engaging body 12 and has an opening at the lower end is fitted onto the outer periphery of the main body 1 and is secured to the upper outer periphery of the main body 1 by a retaining ring 14. A compression spring 15 is stretched between the engaging bodies 12 to urge the wedge center 4 downward.

16 is a threaded portion 17 carved into the upper outer peripheral wall of the main body 1.
Nut 18 is a cylindrical pushing member with an opening at the lower end fixed to the lower surface of the nut 16 in correspondence with the engaging body 12, and the length in the axial direction of the pushing member 18 is usually such that the nut 16 is connected to the threaded portion. The push member 18 and the engaging body 12 are set so as to be joined when screwed in to approximately the middle position of the push member 17.

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

Pre-drilled blind end hole A as shown in figure a
When cutting an enlarged diameter hole in the bottom of the hole, the lower end of the wedge center 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 compression spring 15, the cutting blade 8, which was previously located at the base of the protruding jaw 5 of the wedge center 4, The overhanging jaw 5
starts cutting the hole wall by moving outward along the guide groove 9 of the hole until the cutting edge 8 reaches the maximum overhang point of the overhanging jaw 5, as shown in Figure b. The enlarged diameter hole portion B is formed by cutting the wall.

After the cutting operation is completed, when the rotation of the main body 1 is stopped and the force pressing against the main body 1 is released, the cutting blade 8 is normally moved along the guide groove 9 to its normal position at its base by the biasing force of the compression spring 15. automatically returned to.

However, if the cutting blade 8 gets stuck in the guide groove 9 at the end of the cutting work or during the work, and even if the force pressing against the main body 1 is released, the cutting blade 8 does not automatically return to its normal position at the base. , as shown in figure c,
When the nut 16 is tightened and the pushing member 18 is joined to the engaging body 12 and pushed down, the main body 1 is pulled up against the wedge center 4 and the engagement between the cutting blade 8 and the guide groove 9 is released. Then, the cutting edge 8 moves toward the base along the guide groove 9. In this way, the device can be withdrawn from the hole with the cutting edge 8 returned to the base of the guide groove 9.

(Effects of the invention) As explained above, according to the diameter expansion hole drilling device of this invention, when installing anchor bolts in concrete, etc., it is possible to easily drill holes into pre-drilled pilot holes. It is possible to cut an enlarged diameter part in the wall, which can significantly improve the pullout strength when installing the anchor bolt, and the cutting blade can be used as a guide after cutting the enlarged diameter part in the hole or during the work. Even if the cutting blade gets stuck in the groove and cannot be moved, a simple operation, that is, just tightening the nut, will release the engagement between the cutting blade and the guide groove and move it along the guide groove toward the base of the overhanging jaw. Since the device can be pulled out from inside the hole, it is convenient and has excellent workability, and has the effect of smoothly performing a series of operations from the start of the cutting operation to the pulling out of the device.

[Brief explanation of the drawing]

Fig. 1 is a central vertical sectional view showing an embodiment of this invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 1, and Figs. 4 a, b, c. is an operation explanatory diagram. DESCRIPTION OF SYMBOLS 1... Main body, 4... Wedge center, 5... Protruding jaw, 8... Cutting blade, 9... Guide groove, 12... Engaging body, 15... Compression spring, 16... Nut, 18
...Pushing member.

Claims (1)

[Scope of utility model registration request] A wedge center is inserted into the main body so that it rotates together with the main body and is movable relative to the main body under the force of a spring in the axial direction, and a cutting blade attached to the main body is provided at the tip of the wedge center as a guide with an overhanging jaw. In a diameter expanding hole cutting device that is moved along a groove to protrude outward from an overhanging jaw and inserted into a prepared hole to cut the hole wall,
An engaging body connected to the wedge center via a pin is disposed so as to be movable in the axial direction with respect to the main body, and the upper end of the push member connectable to the engaging body is fixed to a nut screwed onto the upper outer circumferential wall of the main body, An enlarged diameter hole cutting device with a pull-out mechanism, characterized in that by tightening the nut, the engaging body is pushed down via a pushing member to separate the main body from the wedge center.