Bolt removal tools and how to use them

Abstract

To provide an unbolting tool which can remove a bolt having an engagement groove of a head part worn, and a usage of an unbolting tool.SOLUTION: An unbolting tool 1 for removing a bolt 2 having an engagement groove 2b of a head part 2a worn is provided with: a cylindrical first member 10 which has a cylindrical main body part 11, a polygonal tool hook part 12 provided at an outer periphery of the main body part 11, a plurality of expanding parts 13 protruded outward in an axial direction from one end face in the main body part 11 and arranged with an interval in a circumferential direction, sharp blade parts 14 formed on respective outside surfaces of the expanding parts 13 and taper parts 15 provided on respective inside surfaces of the expanding parts 13 and inclined to approach a shaft core as going toward a tip; and a rod-shaped second member 20 which is inserted into the first member 10 through an end part at an opposite side of the expanding parts 13, whose tip side can contact the taper parts 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bolt removing tool for removing a bolt whose engagement groove in the head is worn, and a method of using the bolt removing tool. [Background technology]

[0002] An example of a bolt with an engagement groove on its head is a hexagonal socket bolt, which has an engagement groove on its head with a hexagonal hole on its inner periphery, and 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 into a nearly circular hole (so-called "stripping"), making it impossible to turn the bolt.

[0003] To address this issue, it is known to use pliers to grip the head of the bolt and rotate the pliers to rotate the bolt together 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 cannot be gripped with the pliers.

[0004] Meanwhile, a tool with a tapered, left-handed cutting blade at its 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. The tapered diameter gradually increases, increasing cutting resistance, which causes the bolt to rotate together with the tapered cutting blade, 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, whose cutting edge faces the direction of rotation, scrapes the engagement groove, making it impossible to remove the bolt. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, an object of the present invention is to provide a bolt removal tool that can remove a bolt whose engagement groove in the head is worn, and a method of using the bolt removal tool. [Means for solving the problem]

[0006] 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 the end opposite the widened portion and whose tip side can abut against the tapered portion; Equipped with 、 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 coincides with an extension of the outer circumferential surface of the main body and faces radially outward with respect to the axis of the first member. It is characterized by being "

[0007] In 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 multiple expansion portions have blades on their outer surfaces, 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 receiving portion of the first member and the first member is rotated in the direction in which the bolt will be removed, the bolt will rotate together with the first member and can be removed.

[0008] 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:

[0009] This configuration is a method of using the bolt removal tool described above, which makes it possible to remove a bolt whose engagement groove in the head is worn. [Effects of the Invention]

[0010] As described above, the effect of the present invention is to provide a bolt removal tool and a method of using the bolt removal tool that are capable of removing a bolt whose engagement groove in the head is worn. [Brief explanation of the drawings]

[0011] [Figure 1] (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 longitudinal cross-sectional view of the bolt removal tool, and (f) is a perspective view of the bolt removal tool. [Figure 2] 10(a) to 10(f) are explanatory perspective views showing how to use the bolt removal tool. [Figure 3] 10(a) to 10(c) are explanatory cross-sectional views showing the operation of the bolt removing tool. [Figure 4] FIG. 2 is a vertical cross-sectional view of a bolt removal tool different from that shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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 includes a cylindrical first member 10 and a rod-shaped second member 20 to be inserted into the cylindrical first member 10.

[0013] The first member 10 comprises a cylindrical main body 11, a polygonal tool hook portion 12 provided on the outer periphery of the main body 11, a plurality of expansion portions 13 protruding axially outward from one end face of the main body 11 and provided at intervals in the circumferential direction, a sharp cutting portion 14 provided on the outer surface of each expansion portion 13, and a tapered portion 15 provided on the inner surface of each expansion portion 13 and inclined so as to approach the axis as it approaches the tip.

[0014] The main body 11 is cylindrical, and the outer periphery of the portion where the tool hooking portion 12 is provided is formed into a polygonal shape. The tool hooking portion 12 is provided on the outer periphery of the main body 11 near the end opposite the widened portion 13. In this embodiment, the outer shape of the tool hooking portion 12 is hexagonal. However, the tool hooking portion 12 may have an outer shape other than a hexagon as long as it can hang a tool.

[0015] In this embodiment, six expansion sections 13 are provided at equal intervals in the circumferential direction, but the number is not limited to six. Here, the outer surface of each expansion section 13 is on an extension of the outer circumferential surface of the main body 11.

[0016] The blade portion 14 extends axially from near the axial center to the tip on the outer surface of the expanded portion 13. The blade portion 14 is located in the circumferential center of the expanded portion 13. The blade portion 14 is formed by the outer surface of the expanded portion 13 being recessed in a curved shape on both sides, leaving the circumferential center. Therefore, the cutting edge of the blade portion 14 coincides with the extended plane of the outer peripheral surface of the main body 11 and faces radially outward relative to the axis of the first member 10.

[0017] The tapered portion 15 is provided on the rear side of the portion of the expanding portion 13 where the cutting edge 14 is provided. The entire tapered portion 15 protrudes toward the axial core beyond the inner peripheral 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 peripheral surface.

[0018] 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 in 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 in 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.

[0019] 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 has a polygonal (hexagonal) outer shape, which allows a tool such as a wrench to be applied to the head 22.

[0020] In this embodiment, the first member 10 and the second member 20 are formed by cutting out metal.

[0021] Next, a method of using the bolt removal tool 1 of this embodiment will be described with reference to FIGS. 2 and 3. Here, a hexagon socket head bolt 2 (also simply referred to as bolt 2) will be used as an example of a bolt having an engagement groove 2b in its head 2a. First, FIG. 2(a) shows the bolt 2 attached to the object 3. If the bolt 2 is stuck to the object 3 due to aging or corrosion, when a wrench (not shown) is inserted into the engagement groove 2b to remove the bolt 2 and an attempt is made to rotate the bolt 2, the wrench may turn on its own, depending on the degree of fixation of the bolt 2. If the wrench turns on its own, the engagement groove 2b will be worn down (so-called "stripped") by the wrench, as shown in FIG. 2(b), causing the rectangular hole to become closer to a circle, making it impossible to rotate the bolt 2.

[0022] For the bolt 2 whose engagement groove 2b has been worn in this way, the multiple expansion portions 13 of the first member 10 are inserted into the worn engagement groove 2b (see FIGS. 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 side where the tool engaging portion 12 is provided (see FIGS. 2(d) and 3(b)). In this state, as shown in FIG. 3(b), the tip of the second member 20 abuts against the multiple tapered portions 15 of the first member 10.

[0023] After inserting the second member 20 into the first member 10, a hammer (not shown) or the like is used to strike the head 22 of the second member 20, moving the second member 20 toward the bolt 2 in a driving manner (see FIG. 2(e)). Then, the tip of the second member 20 abutting against the tapered portion 15 presses the expansion portions 13 via the tapered portion 15 in a direction away from the axis, and the multiple expansion portions 13 are plastically deformed and expanded so as to bend outward relative to the main body portion 11.

[0024] Because blade portions 14 are provided on the outer surfaces of the multiple expansion portions 13, as each expansion portion 13 expands, each blade portion 14 approaches and abuts against the worn inner surface of the engagement groove 2b. When the head portion 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 FIG. 3(c)). At this time, because the cutting edge of the blade portion 14 faces radially outward with respect to the axis of the first member 10, it can be reliably bitten into the inner surface of the engagement groove 2b.

[0025] 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 together with the first member 10, and the bolt 2 can be removed from the object 3 (see FIG. 2(f)). At this time, because the cutting edge of the blade portion 14 faces radially outward with respect to the axis of the first member 10 and extends long in the axial direction, 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 rotation direction.

[0026] In the above, a method has been shown in which the first member 10 and the second member 20 are separated, 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, 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.

[0027] In addition, in the above description, the first member 10 is shown as one in which the outer diameter of the main body 11 is the same as the outer diameter of the portions of the plurality of diffusion portions 13, but this is not limited to this, and the outer diameter of the portions of the plurality of diffusion portions 13 may be smaller than the outer diameter of the main body 11. This makes it possible to apply this to bolts 2 with small engagement grooves 2b without impairing the operability of hanging a tool on the tool hanging portion 12 and rotating the first member 10.

[0028] As described above, according to this embodiment, it is possible to remove a bolt 2 in which the engagement groove 2b of the head 2a is worn. In addition, since multiple expansion portions 13 are inserted into the worn head 2a and the tool engaging portion 12 for engaging a tool is located away from the expansion portions 13, it is possible to remove even a bolt 2 in which the head 2a is sunk below the surface of the object 3 due to the counterbore.

[0029] Furthermore, the multiple axially long blade portions 14 are designed to bite into the inner surface of the worn engagement groove 2b, and the cutting edges are not facing the rotation direction for removing the bolt 2, so the blade portions 14 will not scrape the engagement groove 2b even when the first member 10 is rotated, and the multiple blade portions 14 are less likely to slip against the inner surface of the engagement groove 2b, making it possible to remove even large-diameter bolts 2 that experience greater rotational resistance when being removed.

[0030] The present invention has been described above by citing preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible within the scope of the gist of the present invention.

[0031] For example, in the above embodiment, the second member 20 is moved toward the bolt 2 by hitting it with a hammer or the like, but this is not limited thereto. A configuration such as that shown in FIG. 4 may also be used. In FIG. 4, the same components as those described above are denoted by the same reference numerals, and a description thereof will be omitted. The bolt removal tool 1 shown in FIG. 4 has a female thread portion 16 formed of a female screw on the inner circumferential 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 circumferential surface of the insertion main body portion 21 of the second member 20. Thus, 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.

[0032] In the above embodiment, the engagement groove 2b of the head 2a of the bolt 2 has a hexagonal shape in plan view, but this is not limited to this. Examples of the engagement groove include a square, cross & square, hexagonal star, Pozidriv, pin hexagon, tri-wing, pin 5 lobe, pin 6 lobe, and star shape. [Explanation of symbols]

[0033] 1 bolt removal tool 2 Hexagon socket head bolts (bolts) 2a head 2b Engagement groove 3. Mounting object 10 First member 11 Main body 12 Tool rack 13 Expansion section 14 Blade 15 Tapered section 16 Female thread 20 Second member 21 Insertion body 22 Head 23 Male thread

Claims

1. 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 the end opposite the widened portion and whose tip side can abut against the tapered portion; Equipped with 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 coincides with an extension of the outer circumferential surface of the main body and faces radially outward with respect to the axis of the first member. A bolt removal tool characterized by:

2. 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, Thereafter, a tool is applied to the tool application portion to rotate the first member. A method for using a bolt removal tool.

Images