JP7749210B2 - Bolt removal tools and how to use them - Google Patents

Description

The present invention relates to a bolt removal tool for removing bolts whose head engaging grooves are worn, and a method for using the bolt removal tool.

An example of a bolt with an engagement groove on its head is a hexagonal socket bolt, which has an engagement groove consisting of a hexagonal hole on the inner periphery of its head. It can be rotated by inserting a hexagonal wrench (hex wrench) into the engagement groove. Such bolts are used while fastened to the object to which they are attached. However, if the bolt becomes stuck due to aging or corrosion, when the wrench is used to rotate the bolt to remove it, the hexagonal hole wears down into a nearly circular hole (known as "stripping"), making it impossible to rotate the bolt.

A known solution to this problem is to use pliers to grip the head of the bolt and then rotate the pliers to rotate the bolt and remove it. However, depending on how stuck the bolt is, the pliers may slip off the bolt head, making it impossible to remove the bolt. Also, if the bolt head is recessed due to the counterbore hole, it may not be possible to grip it with the pliers.

Meanwhile, a tool with a tapered, left-handed cutting blade at the tip has been proposed. This tool is designed to screw the tapered cutting blade into the worn engagement groove of the bolt while rotating it in the direction that removes the bolt. As the taper diameter gradually increases, cutting resistance increases, and this resistance causes the bolt to rotate along with it, thereby removing the bolt. However, with this technology, as the bolt diameter increases, the rotational resistance of the bolt also increases, so the cutting blade, with its cutting edge facing the direction of rotation, wears away the engagement groove, making it impossible to remove the bolt.

In light of the above situation, the present invention aims to provide a bolt removal tool and a method for using the bolt removal tool that can remove bolts whose engagement grooves in the head are worn.

In order to solve the above problems, the bolt removal tool according to the present invention comprises:
"A bolt removal tool for removing bolts whose head engagement grooves are worn,
a cylindrical first member having a cylindrical main body, a polygonal tool engaging portion provided on the outer periphery of the main body, a plurality of expansion portions protruding axially outward from one end face of the main body and provided at intervals in the circumferential direction, a cutting portion provided on an outer surface of each expansion portion, and a tapered portion provided on an inner surface of each expansion portion and inclined so as to approach an axis as it approaches the tip;
a rod-shaped second member that is inserted into the first member from an end opposite to the expanded portion and has a tip side that can abut against the tapered portion ,
The blade portion is
The expansion portions extend in the axial direction from the center of the outer surface to the tip, and the outer surface of each expansion portion is formed by being curved and recessed on both sides except for the circumferential center,
The cutting edge of the blade portion coincides with an extension of the outer circumferential surface of the main body portion and faces radially outward relative to the axis of the first member .

With this bolt removal tool, the multiple expansion portions of the first member are inserted into a bolt with a worn engagement groove in the head. The second member is inserted from the end of the first member opposite the expansion portions. When the second member is then moved so that its tip approaches the bolt, the tip of the second member abuts the tapered portion, and the tapered portion presses the expansion portions away from the axis. This causes the multiple expansion portions to plastically deform and bend outward relative to the main body, expanding relative to the axis. Because the outer surfaces of these multiple expansion portions are provided with blade portions, as each expansion portion expands, each blade portion approaches and abuts against the inner surface of the engagement groove. When the second member is then further moved toward the bolt, each blade portion bites into the inner surface of the engagement groove. In this state, if a tool such as a wrench is applied to the tool catch on the first member and the first member is rotated in the direction that will remove the bolt, the bolt will rotate along with the first member, allowing it to be removed.

A method of using the bolt removal tool according to the present invention includes:
"This is the method of using the above bolt removal tool,
The plurality of expansion portions of the first member are inserted into the engagement groove of a bolt whose head has worn engagement grooves, and the second member is inserted into the first member from an end portion opposite to the expansion portions;
By moving the second member so that a tip of the second member approaches the bolt, the tip of the second member comes into contact with the plurality of tapered portions, thereby expanding the plurality of expanded portions, and thereby causing each of the blade portions to bite into the inner surface of the engagement groove,
Then, a tool is applied to the tool application portion to rotate the first member.
It is characterized by:

This configuration is a method of using the bolt removal tool described above, which allows you to remove a bolt whose engagement groove in the head is worn.

As described above, the effect of the present invention is to provide a bolt removal tool and a method for using the bolt removal tool that can remove bolts whose engagement grooves in the head are worn.

(a) is a plan view of a bolt removal tool according to one embodiment of the present invention, (b) is a front view of the bolt removal tool, (c) is a bottom view of the bolt removal tool, (d) is a right side view of the bolt removal tool, (e) is a vertical cross-sectional view of the bolt removal tool, and (f) is a perspective view of the bolt removal tool. 10A to 10F are explanatory perspective views showing how to use the bolt removal tool. 10(a) to 10(c) are explanatory cross-sectional views showing the operation of the bolt removal tool. FIG. 2 is a vertical cross-sectional view of a bolt removing tool different from that shown in FIG. 1 .

A bolt removal tool 1 according to one embodiment of the present invention will be described in detail below with reference to Figures 1 to 3. As shown in Figure 1 and other figures, the bolt removal tool 1 comprises a cylindrical first member 10 and a rod-shaped second member 20 for insertion into the cylindrical interior of the first member 10.

The first member 10 comprises a cylindrical main body 11, a polygonal tool catch 12 provided on the outer periphery of the main body 11, a plurality of expansion sections 13 that protrude axially outward from one end face of the main body 11 and are provided at intervals in the circumferential direction, a sharp cutting edge 14 provided on the outer surface of each expansion section 13, and a tapered section 15 provided on the inner surface of each expansion section 13 that slopes toward the axis as it approaches the tip.

The main body 11 is cylindrical, and the outer periphery of the area where the tool hook 12 is provided is formed into a polygonal shape. The tool hook 12 is provided on the outer periphery of the main body 11 near the end opposite the expansion portion 13. In this embodiment, the outer shape of the tool hook 12 is hexagonal. However, the tool hook 12 may have an outer shape other than a hexagon, as long as it can hook a tool.

In this embodiment, six expansion sections 13 are provided at equal intervals in the circumferential direction, but the number is not limited to this. Here, the outer surface of each expansion section 13 is on an extension of the outer peripheral surface of the main body section 11.

The blade portion 14 extends axially from near the axial center to the tip on the outer surface of the expansion portion 13. The blade portion 14 is located in the circumferential center of the expansion portion 13. The blade portion 14 is formed by the outer surface of the expansion portion 13 being curved and recessed on both sides, leaving the circumferential center. Therefore, the cutting edge of the blade portion 14 coincides with the extended surface of the outer peripheral surface of the main body portion 11 and faces radially outward relative to the axis of the first member 10.

The tapered portion 15 is located on the rear side of the portion of the expanding portion 13 where the cutting edge 14 is located. The entire tapered portion 15 protrudes toward the axial core beyond the inner circumferential surface of the main body 11. The surface of the tapered portion 15 is curved in the circumferential direction so as to form part of the conical inner circumferential surface.

The second member 20 has a rod-shaped insertion body portion 21 and a head portion 22 provided at the base end of the insertion body portion 21. The insertion body portion 21 is formed in a truncated cone shape with a diameter that tapers slightly from the base end to the tip. The diameter of the insertion body portion 21 at the base end is slightly smaller than the inner diameter of the body portion 11 of the first member 10. Furthermore, the diameter of the insertion body portion 21 at the tip end is larger than the diameter of the smallest circle where the multiple tapered portions 15 of the first member 10 meet and slightly smaller than the diameter of the largest circle where the multiple tapered portions 15 meet. Therefore, the insertion body portion 21 can be inserted into the first member 10 from the tool engaging portion 12 side, and the inserted tip can abut against the multiple tapered portions 15.

The head 22 of the second member 20 is larger in diameter than the insertion body 21 and has a flat upper surface. This allows the head 22 to be struck with a hammer. The head also has a polygonal (hexagonal) outer shape, which allows a tool such as a wrench to be applied to the head 22.

In this embodiment, the first member 10 and the second member 20 are formed by cutting metal.

Next, a method of using the bolt removal tool 1 of this embodiment will be described with reference to Figures 2 and 3. Here, we will use a hexagon socket head bolt 2 (also simply referred to as bolt 2) as an example of a bolt having an engagement groove 2b in the head 2a. First, Figure 2(a) shows the bolt 2 attached to the object 3. If the bolt 2 becomes stuck to the object 3 in this state due to aging or corrosion, when an attempt is made to remove the bolt 2 by inserting a wrench (not shown) into the engagement groove 2b and rotating the bolt 2, depending on the degree of sticking of the bolt 2, the wrench may turn on its own. If the wrench turns on its own, the wrench may wear down the engagement groove 2b (so-called "stripping"), as shown in Figure 2(b), causing the rectangular hole to become closer to a circle, making it impossible to rotate the bolt 2.

In this way, for a bolt 2 with worn engagement grooves 2b, the multiple expansion portions 13 of the first member 10 are inserted into the worn engagement grooves 2b (see Figures 2(c) and 3(a)). Then, the insertion body portion 21 of the second member 20 is inserted from the end of the first member 10 opposite the expansion portions 13, i.e., the end where the tool engagement portion 12 is provided (see Figures 2(d) and 3(b)). In this state, as shown in Figure 3(b), the tip of the second member 20 abuts against the multiple tapered portions 15 of the first member 10.

After inserting the second member 20 into the first member 10, the head 22 of the second member 20 is struck using a hammer (not shown) or similar tool to drive the second member 20 toward the bolt 2 (see Figure 2(e)). This causes the tip of the second member 20 abutting the tapered portion 15 to press the expansion portions 13 away from the axis via the tapered portion 15, causing the multiple expansion portions 13 to plastically deform and expand so that they bend outward relative to the main body portion 11.

The outer surfaces of these multiple expansion sections 13 are provided with blade portions 14, so as each expansion section 13 expands, each blade portion 14 approaches and abuts against the worn inner surface of the engagement groove 2b. When the head 22 is further struck to move the second member 20 toward the bolt 2, each blade portion 14 bites into the worn inner surface of the engagement groove 2b (see Figure 3(c)). At this time, because the cutting edge of the blade portion 14 faces radially outward relative to the axis of the first member 10, it can be reliably bitten into the inner surface of the engagement groove 2b.

In this state, if a tool such as a wrench (not shown) is applied to the tool engagement portion 12 of the first member 10 and the first member 10 is rotated in the direction that removes the bolt 2, the bolt 2 will rotate along with the first member 10, and the bolt 2 can be removed from the attachment object 3 (see Figure 2(f)). During this operation, because the cutting edge of the blade portion 14 faces radially outward relative to the axis of the first member 10 and extends axially, the cutting edge of the blade portion 14 will not scrape the inner surface of the engagement groove 2b when the first member 10 rotates, and the cutting edge will not slip in the rotational direction.

In the above description, the first member 10 and the second member 20 are separated, and the multiple expansion portions 13 of the first member 10 are inserted into the engagement groove 2b, and then the second member 20 is inserted into the first member 10. However, this is not limited to this method, and the multiple expansion portions 13 of the first member 10 may be inserted into the engagement groove 2b while the second member 20 remains shallowly inserted into the first member 10.

In addition, while the above description shows a first member 10 in which the outer diameter of the main body portion 11 and the outer diameter of the multiple diffusion portions 13 are the same, this is not limited to this, and the outer diameter of the multiple diffusion portions 13 may be smaller than the outer diameter of the main body portion 11. This makes it possible to use a bolt 2 with a small engagement groove 2b without impairing the operability of hanging a tool on the tool hook portion 12 and rotating the first member 10.

As such, this embodiment makes it possible to remove a bolt 2 with worn engagement grooves 2b in the head 2a. Furthermore, by inserting multiple expansion sections 13 into the worn head 2a and providing a tool engagement section 12 away from the expansion sections 13, it is possible to remove even a bolt 2 whose head 2a is recessed from the surface of the object 3 due to the counterbore.

In addition, the multiple axially long blade portions 14 are designed to bite into the worn inner surface of the engagement groove 2b, and because the cutting edges do not face the rotational direction required to remove the bolt 2, the blade portions 14 will not scrape the engagement groove 2b even when the first member 10 is rotated. This makes it difficult for the multiple blade portions 14 to slip against the inner surface of the engagement groove 2b, making it possible to remove even large-diameter bolts 2 that experience significant rotational resistance during removal.

The present invention has been described above using preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention.

For example, in the above embodiment, the second member 20 is moved toward the bolt 2 by striking it with a hammer or the like, as if driving it in. However, this is not limited to this, and a configuration such as that shown in FIG. 4 may also be used. In FIG. 4, the same components as those described above are assigned the same reference numerals and will not be described again. The bolt removal tool 1 shown in FIG. 4 has a female thread portion 16 formed of a female screw on the inner surface of the main body portion 11 of the first member 10, and a male thread portion 23 that threadably engages with the female thread portion 16 on the outer surface of the insertion main body portion 21 of the second member 20. As a result, when the second member 20 is rotated relative to the first member 10, the threading action between the female thread portion 16 and the male thread portion 23 moves the second member 20 toward the bolt 2, achieving the same effect as described above. The second member 20 can be rotated by using a tool such as a wrench on its hexagonal head 22.

In addition, in the above embodiment, the engagement groove 2b of the head 2a of the bolt 2 is shown to be hexagonal in plan view, but this is not limited to this. Examples of the engagement groove include a square, cross and square, hexagonal star, Pozidriv, pin hexagon, tri-wing, pin 5 lobe, pin 6 lobe, and star shape.

1. Bolt removal tool 2. Hexagon socket head bolt (bolt)
2a Head 2b Engagement groove 3 Mounting object 10 First member 11 Main body 12 Tool hooking portion 13 Expanding portion 14 Blade portion 15 Tapered portion 16 Female thread portion 20 Second member 21 Insertion main body 22 Head 23 Male thread portion

Claims (2)

A bolt removal tool for removing a bolt whose head engagement groove is worn,
a cylindrical first member having a cylindrical main body, a polygonal tool engaging portion provided on the outer periphery of the main body, a plurality of expansion portions protruding axially outward from one end face of the main body and provided at intervals in the circumferential direction, a cutting portion provided on an outer surface of each expansion portion, and a tapered portion provided on an inner surface of each expansion portion and inclined so as to approach an axis as it approaches the tip;
a rod-shaped second member that is inserted into the first member from an end opposite to the expanded portion and has a tip side that can abut against the tapered portion ,
The blade portion is
The expansion portions extend in the axial direction from the center of the outer surface to the tip, and the outer surface of each expansion portion is formed by being curved and recessed on both sides except for the circumferential center,
A bolt removal tool characterized in that the cutting edge of the blade portion coincides with the extension of the outer peripheral surface of the main body portion and faces radially outward with respect to the axis of the first member . A method of using the bolt removal tool according to claim 1,
The plurality of expansion portions of the first member are inserted into the engagement groove of a bolt whose head has worn engagement grooves, and the second member is inserted into the first member from the tool engaging portion side;
By moving the second member so that the tip of the second member approaches the tip of the first member, the tip of the second member comes into contact with the plurality of tapered portions and expands the plurality of expanded portions, causing each of the blade portions to bite into the inner surface of the engagement groove,
A method of using a bolt removal tool, characterized in that a tool is then hung on the tool hanging portion to rotate the first member.