JPH0110174Y2 - - 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) When installing 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 the anchor bolt is cut in the axial direction. The blind end cylinder with grooves (slits) is enlarged 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.

When using this device to cut an enlarged diameter section at the bottom of a blind-end pilot hole, for example, 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 force. When the cutting blade, which was previously located at the base of the wedge center's overhanging jaw, is pushed into the hole, the cutting blade, which had been located at the base of the wedge center's overhanging jaw, will extend outward along the wedge center's overhanging jaw due to the movement of the main body. The hole wall is cut while moving to the end, and the overhanging jaw finally reaches the maximum overhanging point and protrudes outward from the overhanging jaw to create an enlarged diameter hole in the hole wall.After this, the main body When the pressing force is released, the cutting blade returns to its normal position at the base of the overhanging jaw of the wedge center under the action of the spring in the reverse order of the movement described above, and the device is withdrawn from the hole.

(Problem to be solved by the invention) By the way, in 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 be returned to its normal position at the cutting work position in the hole. It cannot be pulled out unless it is completely cleared, and when cutting an expanded diameter part at the bottom of the blind end hole, the chips generated by cutting the hole wall remain unremoved, and the cutting edge The cutting blade becomes buried and prevents it from returning to the base of the protruding jaw in its normal position, worsening the return movement of the cutting blade and making it difficult to pull out the device from the hole. may get stuck in the guide groove and become impossible to pull out.

This idea was developed in consideration of the above points, and after cutting the enlarged hole part on the wall of the pilot hole previously drilled in the material to be drilled, such as concrete, the cutting edge is exposed to the overhanging jaw. Equipped with a wedge center push-out mechanism that allows the device to be pulled out even if the cutting blade gets stuck in the guide groove and cannot be returned to its normal position by spring force along the guide groove. The present invention aims to provide a device for cutting an enlarged diameter portion.

(Means for Solving the Problems) The structure of this invention is such that a wedge center is inserted into the main body so that it can rotate together with the main body and the axis and can move relatively in the axial direction under the bias of a spring. The cutting blade attached to the wedge is moved along the guide groove of the overhanging jaw provided at the tip of the wedge center so that it protrudes outward from the overhanging jaw, and is inserted into the prepared hole that has been cut in advance to cut the hole wall. In a diameter expanding hole drilling device that enlarges the diameter by cutting, an engaging body is disposed on the outer periphery of the lower part of the main body so as to be movable in the axial direction, and a pin that is inserted through a vertical hole bored in the peripheral wall of the main body is connected to the engaging body. The gist is that the push rod insertion hole is removably attached to and connected to the wedge center, passes through the shank at the upper end of the main body and the solid part of the main body, and has a push rod insertion hole facing the striking surface of the wedge center at the bottom of the hole. It is something to do.

(Function) The device of this invention connects the engaging body and the wedge center when the cutting blade is stuck in the guide groove and does not automatically return to the normal position at the base even if the force pressing against the main body is released. Remove the pin, insert a push rod through the insertion hole at the upper end of the shank, apply the lower end of the push rod to the striking surface of the wedge center, and hit the push rod with a hammer or mallet to push the wedge center against the main body to remove the impact. The cutting edge moves toward the base of the guide groove due to the reaction force. 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, and a shank 2 connected to a drive shaft (not shown) is rotatably inserted into a central hole formed at the upper end of the main body. Inserted shear pin 3
are connected so as to be integrally rotatable. Reference numeral 4 designates a wedge center, and the lower end of the wedge center 4 forms an overhanging jaw 5 that extends downward and gradually inclines outward.

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. It is configured to engage with the guide groove 9 and move on the overhanging jaw 5. Reference numeral 10 designates a pair of vertically elongated holes formed opposite to the circumferential wall of the hollow portion 6 of the main body 1, and reference numeral 11 designates a cylindrical engagement body having an open upper end and disposed on the outer periphery of the main body 1 so as to be movable in the axial direction of the main body 1. , this engaging body 11
A pin 12, which is inserted through the longitudinal hole 10, is removably inserted into a series of through holes drilled in the lower part of the wedge and the upper end of the wedge center 4 to couple the two. Note that the length of the vertically elongated hole 10 is set to be slightly longer than the maximum movement length by which the cutting blade 8 can move along the guide groove 9. Further, a cylindrical receiving seat 13 with a lower end opening inserted into the outer periphery of the main body 1 facing the engaging body 11 is locked to the upper outer periphery of the main body 1 with a retaining ring 14, and compressed between the receiving seat 13 and the engaging body 11. A spring 15 is tensioned to urge the wedge center 4 downward, and the cutting edge 8 is normally located at the base of the overhanging jaw 5.

16 is an insertion hole for the push rod 17;
is bored through the center of the shank 2 and the solid portion of the main body 1 to reach the hollow portion 6. Therefore, the upper end surface (striking surface) of the wedge center 4 faces the bottom side of the insertion hole 16.

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

As shown in FIG.
The lower end of the hole is placed against the upper surface of the object A to be drilled.

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, and continues cutting the hole wall until reaching the maximum extension point of the overhanging jaw 5, as shown in Figure b. Then, the enlarged diameter hole C is cut.

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 operation or during the operation, and the cutting edge 8 does not automatically return to the normal position at the base even if the force pressing against the main body 1 is released, , As shown in Figure c, first,
After pulling out the pin 12 connecting the wedge center 4 and the engaging body 11, insert the push rod 17 from the insertion hole 16 at the upper end of the shank 2, apply the lower end of the push rod 17 to the upper end surface (impacting surface) of the wedge center 4, and use a hammer or By hitting the push rod 17 with a hammer or the like and pushing out the wedge center 4 against the main body, the impact and reaction force release the engagement between the cutting blade 8 and the guide groove 9, and the cutting blade 8 moves along the guide groove 9. and move toward the base. 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 wedge gets stuck in the groove and cannot be moved, it can be easily operated, that is, the pin 12 connecting the wedge center 4 and the engaging body 11
After pulling out the cutting blade, simply insert the push rod into the insertion hole and tap it to 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 the machine, 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 front view taken along the center only on the left side from the center line showing the configuration of an embodiment of this invention, Fig. 2 is a plan view of the same, Fig. 3 is a view taken along the - line in Fig. 1, and Fig. 4
Figures a, b, and c are explanatory diagrams of the operation. DESCRIPTION OF SYMBOLS 1... Main body, 4... Wedge center, 5... Protruding jaw, 8... Cutting blade, 9... Guide groove, 11... Engaging body, 12... Pin, 15... Compression spring, 16...
...insertion hole, 17...push rod.

Claims (1)

[Scope of Claim for Utility Model Registration] A wedge center is inserted into the main body so that it can rotate together with the main body and the shaft and can move relative to each other in the axial direction under the bias of a spring, and the cutting blade attached to the main body is inserted into the wedge center at the tip of the wedge center. In the diameter expanding hole cutting device, which is moved along the guide groove of the overhanging jaw provided in the main body to protrude outward from the overhanging jaw, and inserted into the prepared hole to cut the hole wall, The engaging body is disposed so as to be movable in the axial direction, and a pin inserted through a vertical hole bored in the peripheral wall of the main body is removably attached to the engaging body and the wedge center, and the shank at the upper end of the main body and the main body are connected. An enlarged diameter hole cutting device with an extrusion mechanism, characterized in that a push rod insertion hole is bored through the solid portion of the hole and faces the striking surface of the wedge center at the bottom side of the hole.