JP2004188526A - Screw extracting tool and extracting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw extracting tool in which a screw can be easily and securely extracted regardless if skillfulness exists or not without giving strong impact even when a cross recess is wholly crushed, and in which a tip part of a male screw part is hard to be broken. <P>SOLUTION: The screw extracting tool 1 has a tapered part 4 which is formed to be gradually contracted in outer diameter toward a tip at one end part of a tool main body 2. In a tip part of the tapered part 4, a male thread part 5 in an inverse spiral direction to a plus thread A to be extracted is engraved. A guide screw part 6 is formed in the same outer diameter for prescribed length at a tip part of the male thread part 5. A tip 6a of the guide screw part 6 is formed flat. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention mainly relates to a screw extracting tool for extracting a screw having a cross-shaped hole in the head of a Phillips screw (or also referred to as a cross-hole screw) and a method of extracting a Phillips screw using the tool.
[0002]
[Prior art]
Conventionally, the above-mentioned Phillips screw has a cross-shaped hole in the screw head, and is screwed by being rotated with a Phillips screwdriver having a positive tooth tip. The Phillips screw has a slightly more complicated hole shape at the head than the minus screw, and has a wider range of engagement with the driver's teeth, making it less likely to collapse. However, when the screw diameter is small, even when using a Phillips screw, the depth of the cross hole in the head is shallow, and the hole may be broken when tightening.
[0003]
To remove such a screw with a broken cross hole, change the height of the tooth at the tip of the Phillips screwdriver so that the two straight teeth are hooked on a part of the cross hole. In the case where all of them are broken, a screw is turned by hitting a straight high tooth (see Patent Document 1).
[0004]
In addition, when turning the head of a bolt with a relatively large outside diameter with a wrench etc. while screwing it, if the head is damaged or broken, use a prepared hole at one end of the handle as a tool to pull out the bolt A structure is provided in which a drill bit for drilling a hole is provided, and at the other end, a male screw portion having a helical direction opposite to that of a pulling bolt is provided on a tapered portion having a gentle inclination (Patent Document 2). reference).
[0005]
Further, as shown in FIG. 3, one end of a handle (tool main body) 21 is formed as a pointed tip as a tool for pulling out the crossed hole in the head of the Phillips screw when the Phillips screw is broken. There has been proposed a screw removing bit having a structure in which a male screw portion 22 for extracting a left screw having a tapered rear portion with a larger diameter than the portion 23 is formed. Then, in the case where a screw having a broken cross hole is to be unscrewed using the same screw unwinding bit, a pilot hole is drilled in the cross hole in the head of the Phillips screw A with a small-diameter drill bit 32 of a dedicated drill 31, and the left hole is removed. A method has also been proposed in which a tip 23 of a male screw portion 22 for extracting a screw is bitten into a prepared hole, and a broken Phillips screw A is rotated to the left to extract the screw (see Patent Document 3).
[0006]
[Patent Document 1]
Japanese Patent No. 2588848 [Patent Document 2]
Japanese Unexamined Patent Publication No. Hei 8-505819 [Patent Document 3]
JP 2001-260047 A
[Problems to be solved by the invention]
However, the conventional extraction tools described in the above publications have the following problems. That is,
(1) With the Phillips screwdriver of Patent Document 1, if all the cross holes are broken, it must be hammered in. However, it is possible to apply a striking force to electric assembly parts that are vulnerable to impact or those using plastic materials or high-grade wood. Can not be used.
[0008]
{Circle around (2)} The tool disclosed in Patent Document 2 is applied when the object to be extracted is a bolt, the head is scattered, and the outer diameter is relatively large. It is not suitable for removing a Phillips screw that is tapered toward the tip. In addition, the tip of the external thread of this tool is flat, and it has a gentle taper that gradually increases the outer diameter toward the base end, so it is difficult to screw into the prepared hole drilled in advance, and the axis of the prepared hole If the direction of the tool does not match the axis of the external thread of the tool, the bolt may be broken.
[0009]
(3) The tool disclosed in Patent Document 3 is for removing a Phillips screw. However, since the tip 23 of the male screw portion 22 is tapered, the axial direction of the prepared hole and the axial direction of the male screw portion are previously drilled. If does not match, the leading end 23 of the male screw portion 22 is shifted from the pilot hole and bites, and the leading end portion may be broken. That is, in the case of a Phillips screw, unlike the case of removing a bolt, a head part having an outer diameter larger than that of the screw part remains, and the cross hole of the head part collapses to form a slippery state. Therefore, if the position where the pilot hole is drilled is shifted from the center of the head, or if the direction of the central axis of the pilot hole is shifted from the direction of the central axis of the Phillips screw, the outer diameter of the screw part is considerably thinner than the head. (See FIG. 1), the screw portion of the Phillips screw is damaged and cannot be removed. In addition, since the screw portion of the Phillips screw is thin and the tip of the male screw is screwed in advance, it takes considerable skill to screw the screw so as to match the central axis of the pilot hole.
[0010]
The present invention has been made in view of the above points, and even when all of the cross holes are collapsed without giving a strong impact, easily and reliably withdrawal regardless of the skill, and the tip of the male screw portion It is an object of the present invention to provide a screw extraction tool and a screw extraction method using the same, which are hard to break.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a screw extraction tool according to the present invention is formed in a tapered tapered portion so that one end of a prismatic tool body gradually decreases in diameter toward the tip, and the tapered portion is formed. At the tip of the tapered part, a male screw part with the spiral direction opposite to the screw to be removed is engraved, and the tip part of the male screw part is formed for a predetermined length on the guide screw part with the same outer diameter And the tip of the guide screw portion is made flat.
[0012]
According to the above-mentioned screw extracting tool, as described in the method of using and the operation in the extracting method according to claim 4 described later, the head of the Phillips screw to be extracted is provided with a guide for the tip of the male screw portion. A straight pilot hole having substantially the same diameter as the screw portion is formed in advance, and a guide screw portion is inserted along the pilot hole. The pilot hole on the Phillips screw side and the guide screw part on the extraction tool side are almost the same diameter, and both are straight shapes (circular holes / cylindrical bodies), so that the guide screw part is inserted into the pilot hole. If the extraction tool is pushed in along the prepared hole, the central axis of the prepared hole and the screw portion naturally match. In this state, the extraction tool is normally rotated in the helical direction of the male screw portion at the distal end, so that the tapered screw portion (large-diameter portion) whose outer diameter increases from the guide screw portion toward the base end side. The Phillips screw is screwed into the inner peripheral surface of the prepared hole of the Phillips screw, and the Phillips screw rotates in the loosening direction together with the extraction tool, and the Phillips screw with the crisscrossed hole in the head is extracted from the screwed member.
[0013]
As set forth in claim 2, the tool main body can be formed in a hexagonal prism shape and have an annular groove for retaining.
[0014]
According to the screw extracting tool of the second aspect, since it corresponds to a general chuck, it can be conveniently attached to most electric drills and impact drivers.
[0015]
Preferably, a drill bit capable of drilling a straight pilot hole having a diameter substantially equal to the outer diameter of the guide screw is provided at the other end of the tool body.
[0016]
According to the screw extracting tool of the third aspect, a special tool for drilling a pilot hole is not required, a pilot hole can be drilled and extracted with one screw, and it is compatible with a guide screw part of a male screw part. Since the drill bit is provided, the prepared hole is not small or large.
[0017]
In the method for extracting a screw according to claim 4, a straight pilot hole having the same diameter or a slightly larger diameter as the guide screw part of the male screw part of the extraction tool is provided in the center of the cross hole of the screw head that has collapsed. The leading end of the male screw portion of the screw extraction tool is pressed into the drilled pilot hole and rotated in the spiral direction of the male screw portion, and the distal end of the male screw portion of the extraction tool is rotated in the pilot hole. After that, the screw is further rotated, and the screw that has collapsed due to the friction rotational force is rotated to pull out the tapered large diameter portion having an outer diameter larger than the pilot hole, thereby extracting the screw. .
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a screw extracting tool according to the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a front view showing a first embodiment of a screw extracting tool, and a drawing showing a cross section of a part of a Phillips screw having a prepared hole, and illustrating the relationship between the two. As shown in FIG. 1, a screw extracting tool 1 includes a tool body 2 having a hexagonal column-shaped cross section which can be used by being attached to a chuck of an impact driver or an electric screwdriver which is used for various purposes. An annular groove 3 for retaining is formed near the base of the main body 2 and has a U-shaped cross section along the circumference in the diameter direction.
[0020]
A tapered portion 4 is formed at one end of the tool body 2 so that the outer diameter gradually decreases toward the tip. A male screw 5 whose helical direction is opposite (left-handed) to the Phillips screw A to be removed is engraved at the tip of the tapered portion 4 and a predetermined length of the tip of the male screw 5 is provided. A guide screw portion 6 having the same outer diameter over (Smm) is formed. Further, the distal end 6a of the guide screw portion 6 is formed as a flat surface as shown in FIG. 1 or formed in a hemispherical portion 6b slightly protruding toward the distal end as shown in FIG. This is because when the guide screw portion 6 is inserted into the straight prepared hole B formed in the Phillips screw A, the direction of the central axis of the guide screw portion 6 is the same as the central axis direction of the prepared hole B. This is to prevent biting into the inner surface of the prepared hole B when not done.
[0021]
The length S of the guide screw 6 is usually 1.0 to 1.5 mm. In addition, the taper angle α of the male screw portion 5 that expands in a taper shape from the base end of the screw portion 6 further toward the base end is set to about 15 ° in the present embodiment.
[0022]
A method of using the extraction tool 1 having the above-described configuration according to the present embodiment will be described with reference to FIG.
[0023]
As shown in FIG. 1, when the cross screw for screwing the tip of the Phillips screwdriver into the head of the Phillips screw A that is screwed into the member C or in the middle of screwing collapses, to remove the Phillips screw A, A straight hole B having substantially the same diameter as the guide screw portion 6 of the extraction tool 1 is drilled in the center of the head of the Phillips screw A with a drill (not shown) as a pilot hole. That is, by drilling a prepared hole with a drill having the same diameter as the screw diameter of the guide screw section 6, the screw diameter of the guide screw section 6 is slightly larger (for example, 2 to 2.2 mm). ) A pilot hole C is formed.
[0024]
Next, with the extraction tool 1 attached to the chuck portion of the electric drill, the guide screw portion 6 at the tip is inserted into the pilot hole B of the plus screw A while rotating in the left-hand screw direction. Since the guide screw portion 6 and the pilot hole B have a common cross-sectional shape and are linearly continuous with each other, the guide screw portion 6 is guided along the pilot hole B. As a result, the central axes of the male screw portion 5 of the extraction tool 1 and the pilot hole B of the Phillips screw A coincide. Therefore, if the extraction tool 1 is pushed into the prepared hole B as it is, the tapered screw portion of the male screw portion 5 located on the base end side of the guide screw portion 6 is screwed into the prepared hole B of the Phillips screw A. The extraction tool 1 is integrated with the Phillips screw A, the torque is transmitted to the Phillips screw A, and the Phillips screw A rotates in the loosening direction and is extracted from the member C.
[0025]
FIG. 2 is a front view showing a second embodiment of the extraction tool of the present invention. As shown in the figure, in the extraction tool 11 of the present embodiment, the length of the guide screw portion 6 provided at the tip of the male screw portion 5 is shorter than that of the first embodiment. At the other end of the tool body 2, a mounting portion 8 for a drill bit 7 for drilling a pilot hole C is provided, and the drill bit 7 is detachably fixed to the mounting portion 8 with a set screw 9. ing. An annular groove 3 for retaining is formed also on the male screw portion 5 side of the tool main body 2 so that the extraction tool 1 can be mounted on an electric drill or the like in a reverse direction. Further, as described above, the distal end of the guide screw portion 6 is projected in a b-hemispherical shape. Therefore, insertion into the prepared hole B can be performed more smoothly. In addition, the drill bit 7 used is such that a pilot hole B having substantially the same diameter as the guide screw portion 6 can be formed. Since other configurations are common, common members are denoted by the same reference numerals and description thereof is omitted.
[0026]
The extraction tool 11 according to the present embodiment does not require a tool for drilling the pilot hole B, and can drill and punch the pilot hole B with a single tool. In addition, since the drill bit 7 which is adapted to the guide screw portion 6 of the male screw portion 5 is provided, the prepared hole B is not small or large.
[0027]
Although the two embodiments of the present invention have been described above, for example, the tool main body 2 is not necessarily limited to a hexagonal prism, and may be a square prism or a cylinder having a shape suitable for a chuck of a tool to be used. . The type of screw to be extracted is mainly a Phillips screw, but since a pilot hole is drilled in advance and the extraction operation is performed, a minus screw can also be extracted in the same manner.
[0028]
【The invention's effect】
As is apparent from the above description, the screw extracting tool according to the present invention has the following excellent effects.
[0029]
When removing a Phillips screw etc. where the fitting part of the screw head is broken, drill a pilot hole in advance and pull out with a removal tool, so all fitting parts such as cross holes are broken without giving a strong impact Even if there is a skill, it can be easily and reliably extracted regardless of the skill and no failure.
[0030]
In particular, since the extraction tool of the present invention is provided with a guide screw portion at the distal end portion of the male screw portion so that it can be smoothly inserted along the prepared hole, misalignment and insertion direction and the center axis direction of the prepared hole are Is unlikely to occur, and unlike the conventional tool (Patent Document 3), the distal end portion of the male screw portion does not break.
[Brief description of the drawings]
FIG. 1 is a front view showing a first embodiment of a screw extracting tool according to the present invention, and a drawing showing a cross section of a part of a Phillips screw having a prepared hole, and explaining the relationship between the two.
FIG. 2 is a front view showing a second embodiment of the extraction tool of the present invention.
FIG. 3 is a front view showing a part of the above-mentioned conventional screw removing tool (Patent Document 3) and a part of a drill for drilling a pilot hole and a plan view of a Phillips screw to be removed.
[Explanation of symbols]
1.1 Extraction Tool 2 Tool Body 3 Retaining Ring Groove 4 Taper 5 Male Thread 6 Guide Screw 7 Drill Bit 8 Mounting 9 Set Screw A Phillips Screw B Prepared Hole

Claims (4)

Form one end of the prismatic tool body into a tapered taper so that the outer diameter gradually decreases toward the tip,
At the tip of the tapered portion, a male screw with a spiral direction opposite to that of the screw to be removed is engraved, and a guide screw having the same outer diameter over a predetermined length at the tip of the male screw is provided. A screw extraction tool, wherein the guide screw portion is formed in a flat portion and the tip of the guide screw portion is made flat. The screw extraction tool according to claim 1, wherein the tool main body has a hexagonal column shape and has an annular groove for retaining. 2. A screw bit according to claim 1, wherein a drill bit capable of forming a straight pilot hole having a diameter substantially equal to the outer diameter of the guide screw portion is provided at the other end of the tool body. tool. At the center of the cross-shaped hole of the screw head that has collapsed, a straight pilot hole having the same diameter or a slightly larger diameter as the guide screw part of the male screw part of the extraction tool is drilled. The tip of the external thread of the screw extraction tool is pressed against and rotated in the helical direction of the external thread, and after the distal end of the external thread of the extraction tool is bitten into the prepared hole, the rotation is further continued. The screw according to any one of claims 1 to 3, wherein the screw which has collapsed due to frictional rotating force is rotated and cut out by biting a tapered large diameter portion having an outer diameter larger than the pilot hole. Extraction method using an extraction tool.

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