JP2001260047A - Unscrewing bit and unscrewing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily unscrew even a screw with a worn-out cross recess in the head without applying impact thereto. SOLUTION: One end of a shank 2 is pointed and is provided with a left-hand unscrewing thread 4 with a large-diameter back area tapering toward the point. After a prepared hole is cut in the center of a worn-out cross recess in a screw head so as to hold the unscrewing thread 4 that bites into it, an unscrewing bit 1 with its point pressed in the prepared hole thus cut is rotated counterclockwise, so that the frictional torque that the unscrewing thread gives as biting into the prepared hole turns the worn-out screw counterclockwise until it is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a screw removing bit for removing a screw having a crushed cross hole in a screw head, and a screw removing method using the same.

[0002]

2. Description of the Related Art Conventionally, in order to remove a crushed cross-shaped hole in a screw head, the height of the teeth at the tip of a Phillips screwdriver is changed so that two high teeth in a straight line are It is known that the screw is turned so that the screw is hung on a part, and when all the cross holes are broken, the tall teeth in a straight line are beaten. (For example, Patent No. 25888
(See No. 48)

[0003]

In the case of the Phillips screwdriver described in the prior art, if all the cross holes are broken, it must be hammered in. The used one had a problem that the impact force could not be applied and it could not be used. The present invention has been made in view of the above problems, and has a screw removing bit that can be easily and reliably removed even when all cross-holes are crushed without giving a strong impact, and a screw remover that removes a screw using the same. It was invented to provide a method.

[0004]

SUMMARY OF THE INVENTION An unthreading bit is formed in which one end of a handle is formed to have a pointed tip, and a left-handed screw is formed so as to be tapered from the tip of the tip and has a large diameter at the rear. . And when removing the screw of the crushed screw, make a pilot hole with a small diameter drill in the cross hole of the head of the crushed screw, make the tip of the screw of the left screw bite into the pilot hole, and turn it to the left. Rotate and pull out the crushed screw.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. The handle 2 of a screwing bit 1 is used by being inserted and attached to, for example, an impact driver used for various purposes or a chuck of an electric driver. A retaining groove 3 is formed in a hexagonal column shape with a cross section of a size that can be formed, and is depressed in a U-shape along the diametrical periphery of the handle 2. The extraction screw 4 is formed as a left-handed screw, the tip is pointed, and the diameter is increased toward the root side, followed by quenching. More specifically, as shown in FIG. 2, for example, the cutting edge angle θ of the extraction screw 4 is 45 °, and the taper angle α at which the diameter increases from the tip to the rear side is about 15 to 20 °, most preferably 17 °. Then I got a good result. The lead of the extraction screw 4 is preferably about 0.5 m / m, and the number of threads is preferably 8 to 15 threads.

Next, a method of unscrewing using the unscrewing bit 1 of the present invention will be described. First, as shown in FIG. 3, a drill D having a diameter of about 1-2 m / m is attached to a chuck C of an impact driver M, for example. And a pilot hole is drilled to a depth of about 1-2 m / m so that the extraction screw 4 can easily bite into the center of the cross hole T in the head of the crushed screw N. When the tip of the extraction bit 1 with the handle 2 attached to the chuck C of the impact driver M is pressed into the hole and rotated counterclockwise, the diameter becomes larger as the extraction screw 4 bites into the prepared hole. As a result, the friction rotational force increases and is transmitted to the cross-shaped hole, and the screw with the crushed cross-shaped hole is turned to the left, so that the screw can be immediately removed. Even if an impact driver cannot be used, any handwheel or tool that can hold and rotate the handle 2 can be used.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The handle 2 is not necessarily limited to a hexagonal prism, but a shape suitable for a chuck of a tool to be used.
For example, it may be a square pole or a cylinder.

[0008]

As described above, the screw removing bit according to the present invention has a large diameter and the friction rotational force increases as the tip of the extraction screw bites into the point, so that a large left rotational force is applied to the cross hole. It can be added, and even a screw that is strongly tightened can be removed without impact.

[Brief description of the drawings]

FIG. 1 is a front view of a screw removing bit.

FIG. 2 is an enlarged view of a removal screw portion of a screw removal bit.

FIG. 3 is a diagram illustrating a method for removing screws using a screw removal bit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw removal bit 2 Handle 3 Retaining groove 4 Removal screw

Claims (3)

[Claims] 1. A screw removing bit in which one end of a handle is formed to have a pointed tip, and a left-handed screw is formed to have a tapered rear end with a larger diameter than the pointed tip of the tip. 2. The screw removal bit according to claim 1, wherein the handle has a hexagonal column shape, and a retaining groove is formed in the recess. 3. A hole prepared by the extraction screw is drilled in the center of the cruciform hole of the crushed screw head, and the tip of the screw removal bit is pressed counterclockwise into the drilled hole. A method for removing a screw using a screw removing bit, wherein the screw is rotated to the left to remove the screw that has been crushed by the frictional rotating force that the removal screw bites into the prepared hole.