JP7589952B2 - Method and tool for fastening a bolt with an engaging portion - Google Patents

Description

The present invention relates to a method for fastening a bolt with an engagement part that has an engagement part at the tip of the male thread, and a fastening tool for a bolt with an engagement part.

Conventionally, when fastening parts with a bolt and a nut, a so-called "one-sided bolt" has been known that allows the bolt and nut temporarily fixed between the parts to be tightened only from one of the parts (see Patent Document 1).

Additionally, tools such as those disclosed in Patent Documents 2 and 3 are known for fastening one-sided bolts.

Patent No. 2723493 Japanese Unexamined Patent Publication No. 47-24698 Special Publication No. 2021-511220

The fastening tools in Patent Documents 2 and 3 are attached to the tip of an electric power tool and can apply a rotational force to the bolt side, but the fastening tool in Patent Document 2 in particular has a complex attachment structure to the electric power tool, making it difficult to use as a general-purpose product. In addition, the inner member that holds the engagement part at the tip of the bolt is also difficult to use as a general-purpose product.

Furthermore, with either fastening tool, it is difficult to confirm whether the engaging portion at the tip of the bolt is securely engaged with the inner member.

The present invention was made in consideration of these points, and its purpose is to provide a simple structure that allows an engaging bolt to be easily and reliably tightened from one side using an electric tool.

To achieve the above objective, this invention provides an outer member that prevents the nut to be tightened from rotating, and an inner member that engages with the second engagement part of the bolt with engagement part, and transmits the rotational force of the power tool to the bolt with engagement part to rotate it, and in particular adjusts the speed at which the inner member engages with the second engagement part.

Specifically, in the method for fastening the engaging bolt of the first invention,
a bolt with engagement portions, comprising: a bolt head that can be gripped and tightened with a tool; a rod-shaped bolt body that is continuous with the bolt head; a male thread portion on the tip side of the bolt body; a first engagement portion at the tip of the male thread portion, the first engagement portion having anti-loosening projections that are spaced apart in the circumferential direction; and a second engagement portion provided at the tip of the first engagement portion, the second engagement portion having a projection for tool engagement.
a locking nut having a female threaded portion that screws into the male threaded portion of the engagement bolt and has a locking portion that engages with the locking protrusion of the first engagement portion to lock the engagement bolt from loosening; and
a preparation step for preparing a fastening tool for a bolt with an engagement portion, the fastening tool comprising: a cylindrical outer member, the base end of which is fixed to the electric tool, the cylindrical outer member being disposed at a distance in the radial direction of a rotating shaft of the electric tool, and the tip end of which prevents rotation of a nut temporarily fastened to the bolt with an engagement portion; and an inner member, the cylindrical outer member being disposed at a distance in the radial direction inside the outer member, the base end of which is fixed to the rotating shaft so as to rotate integrally, and the tip end of which engages with the engagement portion at the tip of the bolt with an engagement portion;
a temporary fixing step of inserting the engaging bolt from the first fixed member side into through holes of a first fixed member and a second fixed member, and temporarily fixing the locking nut to the engaging bolt from the second fixed member side;
a bolt setting step of inserting a tip of an outer member of the fastening tool from the locking nut side and bringing a tip of the inner member into contact with the second engaging portion of the engaging portion-equipped bolt;
a bolt engaging step of rotating a rotary shaft of the electric power tool at a first rotation speed for a predetermined time, and threading the engaging portion-equipped bolt to engage a tip end of the inner member with a second engaging portion of the engaging portion-equipped bolt;
The method includes a fastening process in which, after the predetermined time has elapsed, the engaging bolt is screwed in at a second rotational speed faster than the first rotational speed to tighten the first fixed member and the second fixed member, and the anti-loosening protrusion of the first engaging portion of the engaging bolt is engaged with the anti-loosening portion of the nut to prevent loosening.

According to the above configuration, by rotating the rotating shaft of the electric power tool while the engaging bolt and the locking nut are temporarily fixed to the tip side of the outer member and the inner member, respectively, the male thread of the engaging bolt screws into the female thread of the locking nut, reliably fixing the first fixed member and the second fixed member, and providing a locking effect between the locking protrusion and the locking portion. Furthermore, since the rotation speed of the electric power tool is suppressed during the bolt engagement process in which the tip of the inner member is engaged with the second engaging portion of the engaging bolt, the tip of the inner member is reliably engaged with the second engaging portion. After engagement, the engaging bolt can be tightened at a faster rotation speed as usual.

In a second aspect of the present invention, there is provided a cylindrical outer member having a base end fixed to an electric power tool, disposed at a distance in a radial direction of a rotation shaft of the electric power tool, and configured to prevent rotation of a nut temporarily fastened to a bolt with an engagement portion at a tip end;
an inner member disposed inside the outer member with a radial gap therebetween, the inner member having a base end fixed to the rotary shaft so as to rotate integrally with the rotary shaft and a tip end engaging with the tool engaging portion at the tip end of the engaging portion-equipped bolt;
The power tool is configured to include a control unit that automatically switches the rotational speed of the power tool so as to rotate the rotating shaft of the power tool at a first rotational speed for a predetermined time, screw in the bolt with engagement portion to engage the tip of the bolt with engagement portion with the tip of the inner member, and after the predetermined time has elapsed, screw in the bolt with engagement portion at a second rotational speed faster than the first rotational speed to fasten the fixed member.

According to the above configuration, the bolt with engagement portion, whose second engagement portion is engaged with the tip of the inner member, is rotated while the tip of the outer member prevents the nut from rotating, so that the bolt with engagement portion can be easily and reliably fastened to the nut using a power tool. The control unit suppresses the rotation speed of the power tool during the bolt engagement process in which the tip of the inner member is engaged with the second engagement portion of the bolt with engagement portion, so that the tip of the inner member is reliably engaged with the second engagement portion. After engagement, the bolt with engagement portion can be fastened at a faster rotation speed as usual.

In a third aspect of the present invention, in the second aspect of the present invention,
The inner member has an engaged hole that supports the engaging portion of the engaging portion-equipped bolt so that the engaging portion can advance and retreat in the axial direction.

With the above configuration, when the bolt with the engaging portion is screwed in using a power tool, the engaging portion advances through the engaged hole while the nut remains fixed by the outer member, so the bolt with the engaging portion is not hindered from screwing in.

In a fourth aspect of the present invention, in the second or third aspect of the present invention,
The engaged hole at the tip of the inner member is polygonal, and each side of the inner peripheral surface of the engaged hole is formed with an inclined portion that facilitates the introduction of the second engaging portion of the engaging portion-equipped bolt.

With the above configuration, the rotational force of the power tool is effectively transmitted by the inclined guide portions provided on each side of the inner circumferential surface of the polygonal engaged hole so that the second engaging portion can easily engage with the engaged hole of the inner member.

In a fifth aspect of the present invention, in any one of the second to fourth aspects of the present invention,
The outer member is disposed on the power tool at a radial distance from the rotary shaft and has legs whose base ends are fixed to the main body of the power tool.

The above configuration allows for easy and secure attachment to various power tools using the legs.

As described above, according to the present invention, an outer member that prevents the nut to be tightened from rotating and an inner member that engages with the second engagement portion of the engagement bolt are provided, and the rotational force of the power tool is transmitted to the engagement bolt to rotate it, and the inner member is rotated at a low speed when the tip of the inner member is engaged with the second engagement portion and then at a normal rotational speed. This makes it possible to easily and reliably tighten the engagement bolt from one side using a power tool with a simple configuration.

1 is a front view showing an electric power tool to which a fastening tool for an engagement portion-equipped bolt is fixed. 1 is a side view showing an electric power tool to which a fastening tool for an engagement portion-equipped bolt is fixed. 1A is a left side view of a bolt with an engagement portion, FIG. 1B is a front view of the bolt, and FIG. 1 is a front view showing a state in which the locking nut is fastened to the engagement bolt to prevent loosening. FIG. 1 is a front view showing a state in which the locking nut is temporarily fastened to the engagement portion-equipped bolt. FIG. 1A is a left side view of a locking nut, FIG. 1B is a front view of the locking nut, and FIG. 1 is a plan view showing a state in which an engagement bolt and a locking nut are attached to a fastening tool for the engagement bolt. FIG.

The following describes an embodiment of the present invention with reference to the drawings.

- Structure of the bolt with engagement part -
3 shows an embodiment of the bolt 1 with an engagement portion according to the present invention, which is an integrally molded product made of reinforced fiber resin, such as a reinforced fiber synthetic resin containing glass fiber, carbon fiber, etc. Examples of synthetic resins include thermoplastic resins such as polyamide resin (PA), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and ABS resin, and thermosetting resins such as epoxy resin and vinyl ester resin. As such, since the bolt 1 with an engagement portion is an integrally molded product made of reinforced fiber resin, it is possible to easily mold a bolt with a relatively high rigidity even if it has a complex shape.

The engaging bolt 1 has, for example, a hexagonal bolt head 2 that can be gripped and tightened with a tool such as a torque wrench. This may also be a hexagonal socket head.

The bolt with engagement portion 1 has a rod-shaped bolt body 3 that is continuous with the bolt head 2, and in this embodiment, this bolt body 3 has a cylindrical portion with no irregularities and a male thread portion 4 at the tip side.

The tip of the male thread portion 4 is provided with a first engagement portion 5 having anti-loosening projections 5a spaced apart in the circumferential direction. The anti-loosening projections 5a extend in the longitudinal direction of the bolt body 3 and form ridges that are spaced apart in the circumferential direction.

As shown in a partially enlarged view in FIG. 3(c), the locking protrusion 5a is composed of an external toothed ratchet wheel with a substantially triangular cross section of the same shape and size. Specifically, the external toothed ratchet wheel has an outer meshing surface 5b included in the same imaginary plane as the axis of the bolt body 3, and an outer tapered surface 5c that is inclined from the tip of the outer meshing surface 5b toward the tightening direction of the locking nut 10 relative to the outer meshing surface 5b. The external toothed ratchet wheel provides an optimal locking protrusion 5a that allows rotation in the tightening direction and prevents rotation in the loosening direction. The locking portion 11 of the locking nut 10 that fits into the outer meshing surface 5b will be described later.

At the tip of the first engagement portion 5, a second engagement portion 6 is provided having a tool engagement protrusion 6a that engages with the tip of the inner member 25 of the fastening tool 20 described below. The second engagement portion 6 is, for example, a regular hexagonal prism whose corners form the tool engagement protrusions 6a. However, it may also be a triangular prism, a square prism, or the like, as long as the tool can be engaged. If the second engagement portion 6 has a polygonal cross section, it can be easily fastened with a tool such as a wrench or pliers.

In this embodiment, the tip of the second engagement portion 6 is formed with a tapered portion 6b that tapers toward the tip. The tapered portion 6b is formed by C-chamfering each side of the tip of the regular hexagonal prism. The amount of chamfering is preferably 10% to 20% of the nominal bolt diameter of the male thread portion 4. This is because the tool introduction effect is reduced if the amount is less than 10% or more than 20%. For example, C2 chamfering is performed for M12, and C3 chamfering is performed for M16.

This chamfering can be done after the bolt with engagement part 1 is integrally molded, but it is preferable to do it at the same time as the bolt is integrally molded, as this makes manufacturing easier.

The tapered portion 6b may be configured with a tapered surface that is rounded like a pencil. In that case, the tip does not need to be sharp.

In addition, it is desirable for the tapered portion 6b to have a symmetrical shape with respect to the bolt shaft, but it may be eccentric or asymmetrical to match the shape of the tool.

As shown in FIG. 3(c), the circumferential pitch P1 of the anti-loosening protrusions 5a is smaller than the circumferential pitch P2 of the tool engagement protrusions 6a of the second engagement portion 6 (i.e., the distance between the vertices of the hexagonal prism) (P1<P2). In this way, by reducing the circumferential pitch P1 of the anti-loosening portion 11, the anti-loosening effect is improved, and by increasing the circumferential pitch P2 of the tool engagement protrusions 6a, the torque of the tool can be easily transmitted.

As shown in an enlarged view in FIG. 3(b), the maximum outer diameter D1 of the first engagement portion 5 is larger than the maximum outer diameter D2 of the second engagement portion 6 (D1>D2). A step portion 7 is provided between the first engagement portion 5 and the second engagement portion 6.

In this way, by providing the step 7 between the two engagement parts 5, 6, it is possible to prevent the first engagement part 5 from being scratched by a tool engaged with the second engagement part 6. The size of the step 7 is not particularly limited, but if it is too small, the effect is reduced. Also, as shown in the figure, the maximum diameter D1 of the first engagement part is smaller than the maximum diameter D3 of the male thread part and larger than the maximum diameter D2 of the second engagement part (D2<D1<D3).

- Configuration of fastening tool for bolt with engaging part -
As shown in Fig. 1 and Fig. 2, in this embodiment, a dedicated fastening tool 20 is used to fasten the above-mentioned engaging bolt 1. The fastening tool 20 of the present invention includes a cylindrical outer member 24 whose base end is fixed to the electric power tool 21, which is arranged at a distance in the radial direction of the rotation shaft 21a of the electric power tool 21, and which prevents the locking nut 10, which is temporarily fixed to the engaging bolt 1 at its tip end, from rotating. Specifically, the outer member 24 includes, for example, four legs 22 whose base end is fixed to the main body of the electric power tool 21 and whose tip end is fixed to the leg mounting hole 23c of the disk-shaped flange portion 23. The legs 22 are arranged at 90° intervals in the circumferential direction, and each of them maintains a sufficient distance in the radial direction from the rotation shaft 21a of the electric power tool 21. By using the legs 22 to attach the tool to the electric power tool 21, it is possible to relatively easily and reliably attach the tool even if the shape of the electric power tool 21 is different.

As shown in a partially enlarged view in FIG. 2, the outer member 24 has a cylindrical shape with a regular hexagonal cross section, and its base end is inserted into the through hole 23a of the flange portion 23, and its chamfered portion 24c abuts against the flat surface 23b formed in the through hole 23a, and is fixed at the flat surface 23b by a fastening member (not shown) or the like. The outer member 24 is made of, for example, a resin molded product.

A nut through hole 24b with a regular hexagonal cross section is provided at the tip side of the outer member 24, and the anti-loosening nut 10 described below can be fitted into this nut through hole 24b.

On each side of the inner peripheral surface of the nut through hole 24b at the tip of the outer member 24, an introduction inclined portion 24d is formed to promote the introduction of the locking nut 10. Specifically, as shown in Figures 2A and 2B, the nut through hole 24b is a regular hexagon, and each side is machined to gradually incline toward the axial direction so that the locking nut 10 fits into the nut through hole 24b after the locking nut 10 abuts. By providing drill holes 24e between each side, the introduction inclined portion 24d can be easily machined. The introduction inclined portion 24d formed on each side is more preferably inclined not only in the axial direction but also clockwise or counterclockwise along each side, which enhances the introduction effect.

As shown in FIG. 7, an opening 24a is provided on, for example, the upper surface side of the outer member 24, which exposes the anti-loosening nut 10 and the tip side of the engagement bolt 1 that are prevented from rotating by the outer member 24. Note that such an opening may also be provided on the underside. Providing an opening on the underside also improves workability.

Inside the outer member 24, inner members 25 are arranged with radial spacing. As shown in a partially enlarged view in FIG. 2, the inner member 25 is, for example, cylindrical with a regular hexagonal cross section, with a hexagonal engaged hole 25a formed therethrough. The base end of the engaged hole 25a is fixed to the rotating shaft 21a so as to rotate together with the rotating shaft, and the tip end is adapted to engage with the second engaging portion 6 at the tip of the engaging portion bolt 1.

The outer member 24 and the inner member 25 may be painted, plated, etc., to prevent corrosion.

As shown in FIG. 6, the locking nut 10 has a female threaded portion 12 on the inner peripheral surface at the base end side that screws into the male threaded portion 4 of the engaging bolt 1, and a split portion 13 having a locking portion 11 that engages with the locking protrusion 5a of the first engaging portion 5 of the engaging bolt 1 is integrally molded at the tip end side. In this embodiment, the locking portion 11 is an inner ratchet wheel that fits into the locking protrusion 5a (outer ratchet wheel) of the first engaging portion 5. The locking nut 10 is, for example, the same one-piece molded product made of reinforced fiber resin as the engaging bolt 1, and the end face of the regular hexagonal column portion may be chamfered.

As shown in a partially enlarged view in FIG. 6(c), the locking portion 11 has an inner meshing surface 11a that is included in the same imaginary plane as the axis of the locking nut 10, and an inner tapered surface 11b that is inclined from the tip of the inner meshing surface 11a toward the tightening direction of the female thread portion 12 relative to the inner meshing surface 11a.

A smooth buffer section 14 is provided between the anti-loosening section 11 and the female thread section 12, and the dividing section 13 has multiple, for example, four, notches 15 spaced apart in the circumferential direction.

The inner member 25 has an engaged hole 25a that supports the second engaging portion 6 of the engaging bolt 1 so that it can advance and retreat in the axial direction. Like the outer member 24 of the inner member 25, it is made of, for example, a resin molded product. In this embodiment, the engaged hole 25a is configured as a regular hexagonal through hole that matches the regular hexagonal column shape of the second engaging portion 6. As a result, when the engaging bolt 1 is screwed in by the power tool 21, the second engaging portion 6 advances through the engaged hole 25a while the outer member 24 keeps the locking nut 10 fixed, so that the engaging bolt 1 is not hindered from screwing in.

As with the outer member 24, each side of the inner peripheral surface of the engaged hole 25a at the tip of the inner member 25 is formed with an introduction inclined portion 25b that promotes the introduction of the second engaging portion 6 of the engaging bolt 1. Specifically, as shown in Figures 2A and 2C, the engaged hole 25a is also a regular hexagon, and each side is machined to gradually incline toward the axial direction so that the engaging bolt 1 fits into the engaged hole 25a after the second engaging portion 6 abuts. In addition, drill holes 25c are provided between each side, making it easy to machine the introduction inclined portion 25b.

For example, the power tool 21 includes a built-in control unit 40 having a microcomputer or the like, and this control unit 40 can be programmed to rotate the rotating shaft 21a of the power tool 21 at a first rotational speed for a predetermined time, thread the engaging bolt 1 to engage the tip of the engaging bolt 1 with the tip of the inner member 25, and then, after the predetermined time has elapsed, thread the engaging bolt 1 at a second rotational speed faster than the first rotational speed to fasten the first and second fixed members 31, 32.

-Method of fastening bolt with engagement part-
First, in a preparation step, the above-mentioned fastening tool 20 is prepared and fixed to the power tool 21. A necessary number of the above-mentioned engaging bolts 1 and locking nuts 10 are prepared. Although not shown in particular, washers made of, for example, fiber-reinforced resin may also be prepared if necessary.

Next, in the temporary fastening process, the engaging bolt 1 is inserted through the through holes of the first and second fixed members 31 and 32 from the first fixed member 31 side, and the locking nut 10 is temporarily fastened to the tip of the engaging bolt 1 from the second fixed member 32 side, as shown in FIG. 5. The temporary fastening can be performed within a range that allows easy rotation by hand, but it is desirable that the male threaded portion 4 of the engaging bolt 1 and the female threaded portion 12 of the locking nut 10 engage with each other.

Next, in the bolt setting process, the tip of the outer member 24 is inserted from the anti-loosening nut 10 side.

At this time, an introduction inclined portion 24d that encourages the introduction of the locking nut 10 is formed on each side of the inner surface of the nut through hole 24b at the tip of the outer member 24. If the position of the locking nut 10 and each side of the nut through hole 24b are misaligned, the corner of the locking nut 10 will come into contact with the introduction inclined portion 24d of the nut through hole 24b, and if pressed in this state, the locking nut 10 will rotate and be guided so that it fits into the tool.

Next, the engaged hole 25a at the tip of the inner member 25 is brought into contact with the second engaging portion 6 of the engaging bolt 1. As shown by the arrow in Figure 5, the power tool 21 is advanced while the second engaging portion 6 of the engaging bolt 1 is brought into contact with the engaged hole 25a of the inner member 25.

At this time, the locking nut 10 is fitted into the nut through hole 24b, and the power tool 21 is advanced on the same axis, so the second engaging portion 6 of the bolt with engaging portion 1 can be easily brought into contact with the engaged hole 25a of the inner member 25. As shown in FIG. 7, the locking nut 10 and the tip of the bolt with engaging portion 1 are exposed from the opening 24a of the outer member 24, so the contact between the second engaging portion 6 and the engaged hole 25a of the inner member 25 can be confirmed by looking at these.

Next, in the bolt engagement process, the rotating shaft 21a of the power tool 21 is rotated at a first rotation speed for a predetermined time, and the engaging bolt 1 is threaded to engage the tip of the inner member 25 with the second engaging portion 6 of the engaging bolt 1.

The first rotation speed is preferably, for example, 100 rpm or more and 150 rpm or less, and in this embodiment, it is 130 rpm. If the first rotation speed exceeds 150 rpm, the rotation is too fast and the tip of the inner member 25 cannot be inserted into the second engagement portion 6.

The specified time is preferably within 5 seconds, more preferably within 2 seconds, to reduce the time required for fastening work, and is 1 second in this embodiment.

However, in the bolt setting process, it is desirable for the fastening tool 20 to rotate at least 360/N° (N indicates the case where the second engagement portion 6 is a regular N-sided polygon, 60° for a hexagon and 90° for a square), preferably at least one full rotation. The lower limit of the rotation speed can be determined from the shape of the second engagement portion 6 and the time setting.

During the engagement process in which the tip of the inner member 25 is engaged with the second engagement portion 6 of the engagement bolt 1, the rotation speed of the power tool 21 is suppressed, so that the tip of the inner member 25 is reliably engaged with the second engagement portion 6.

In addition, since an introduction inclined portion 25b is formed in the engaged hole 25a at the tip of the inner member 25, the rotational force of the power tool 21 is effectively transmitted by the introduction inclined portion 25b so that the second engaging portion 6 can easily engage with the engaged hole 25a.

Furthermore, when engaging the tool engagement protrusion 6a of the second engagement part 6 with the engaged hole 25a, the tip of the second engagement part 6 is also provided with a tapered part 6b, which, combined with the effect of the introduction inclined part 25b, makes it easy to insert and facilitates the fastening operation.

Next, in the fastening process, after the above-mentioned predetermined time has elapsed, the speed is automatically switched to a second rotation speed that is faster than the first rotation speed. The second rotation speed is, for example, a general fastening speed (approximately 1000 to 5000 rpm), and in this embodiment, is approximately 2000 rpm. The rotating shaft 21a of the power tool 21 is rotated at this second rotation speed, the engaging bolt 1 is screwed in, and as shown in FIG. 4, the first fixed member 31 and the second fixed member 32 are fastened, and the first engaging portion 5 of the engaging bolt 1 is engaged with the anti-loosening portion 11 of the nut 10 to prevent loosening.

In this way, when the bolt 1 with the engaging portion is screwed in by the power tool 21, the outer member 24 holds the nut 10 in place while the engaging portion advances through the engaged hole 25a, so the bolt 1 with the engaging portion is not hindered from screwing in.

In this embodiment, the first engagement portion 5 is fastened to the locking portion 11 of the locking nut 10 to provide an anti-loosening effect. In addition, the male thread portion 4 can be screwed in and fastened by engaging and rotating the fastening tool 20 using the tool engagement protrusion 6a from the tip side.

In this embodiment, the engaging bolt 1 and the locking nut 10 are temporarily fixed at the tip of the outer member 24 and the inner member 25, respectively, and the rotating shaft 21a of the power tool 21 is rotated, so that the male threaded portion 4 of the engaging bolt 1 screws into the female threaded portion of the locking nut 10, reliably locking the first fixed member 31 and the second fixed member 32 together, and providing an anti-loosening effect between the first engaging portion 5 and the locking portion 11.

The rotation speed of the power tool 21 is suppressed during the bolt engagement process in which the tip of the inner member 25 is engaged with the second engagement portion 6 of the bolt with engagement portion 1, so that the tip of the inner member 25 is reliably engaged with the second engagement portion 6 without freewheeling. After engagement, the rotation speed is automatically switched to the normal, faster speed, so that the bolt with engagement portion 1 can be fastened quickly and reliably, eliminating the need for extra work such as realignment, and in fact shortening the overall process time.

As described above, according to the present invention, an outer member 24 is provided to prevent the locking nut 10 to be tightened from rotating, and an inner member 25 is provided to engage with the second engagement portion 6 of the bolt with engagement portion 1. The rotational force of the power tool 21 is transmitted to the bolt with engagement portion 1 to rotate it, and the tip of the inner member 25 is rotated at a low speed when it is engaged with the second engagement portion 6, and then rotated at a normal rotational speed. This allows the bolt with engagement portion 1 to be easily and reliably tightened from one side using the power tool 21 with a simple configuration.

Note that the above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

1. Bolt with engagement part
2 Bolt head
3 Bolt body
4 Male thread
5 First engagement portion
5a Anti-loosening protrusion
5b Outer meshing surface
5c Outer tapered surface
6 Second engagement portion
6a Tool engagement protrusion
6b Tapered portion
7. Step
10 Anti-loosening nut
11 Anti-loosening part
11a Inner meshing surface
11b Inner tapered surface
12 Female thread portion
14 Buffer section
15 Notch
20 Fastening tools
21 Power tools
21a Rotation shaft
22 Legs
23 Flange portion
23a through hole
23b Flat surface
23c Leg mounting hole
24 Outer member
24a Opening
24b Nut through hole
24c Chamfered part
24d Introduction inclined portion
24e Drill hole
25 Inner member
25a Engaged hole
25b Introduction inclined portion
25c Drill hole
31 First fixed member
32 Second fixed member
40 Control unit

Claims (5)

a bolt with engagement portions, comprising: a bolt head that can be gripped and tightened with a tool; a rod-shaped bolt body that is continuous with the bolt head; a male thread portion on the tip side of the bolt body; a first engagement portion at the tip of the male thread portion, the first engagement portion having anti-loosening projections that are spaced apart in the circumferential direction; and a second engagement portion provided at the tip of the first engagement portion, the second engagement portion having a projection for tool engagement.
a locking nut having a female threaded portion that screws into the male threaded portion of the engagement bolt and has a locking portion that engages with the locking protrusion of the first engagement portion to lock the engagement bolt from loosening; and
a preparation step for preparing a fastening tool for a bolt with an engaging portion, the fastening tool comprising: a cylindrical outer member, the base end of which is fixed to the electric tool, the cylindrical outer member being disposed at a distance in the radial direction of a rotating shaft of the electric tool, and the tip end of which prevents rotation of a nut temporarily fastened to the bolt with an engaging portion; and an inner member, the base end of which is disposed at a distance in the radial direction inside the outer member, the cylindrical outer member being fixed to the rotating shaft so as to rotate integrally, the tip end of which supports the second engaging portion at the tip of the bolt with an engaging portion so as to be movable forward and backward in the axial direction, and which engages with the second engaging portion ;
a temporary fixing step of inserting the engaging bolt from the first fixed member side into through holes of a first fixed member and a second fixed member, and temporarily fixing the locking nut to the engaging bolt from the second fixed member side;
a bolt setting step of inserting a tip of an outer member of the fastening tool from the locking nut side and bringing a tip of the inner member into contact with the second engaging portion of the engaging portion-equipped bolt;
a bolt engaging step of rotating a rotary shaft of the electric power tool at a first rotation speed for a predetermined time, and threading the engaging portion-equipped bolt to engage a tip end of the inner member with a second engaging portion of the engaging portion-equipped bolt;
a fastening step of screwing the engaging portion-equipped bolt at a second rotational speed faster than the first rotational speed after the predetermined time has elapsed, thereby tightening the first fixed member and the second fixed member, and engaging the anti-loosening protrusion of the first engaging portion of the engaging portion-equipped bolt with the anti-loosening portion of the nut to prevent loosening. a cylindrical outer member having a base end fixed to the power tool, disposed at a distance in a radial direction of a rotation shaft of the power tool, and configured to prevent rotation of a nut temporarily fastened to the engagement bolt at a tip end;
an inner member disposed inside the outer member with a radial gap therebetween, the base end side of which is fixed to the rotary shaft so as to rotate integrally with the rotary shaft, and the tip side of which supports the tool engagement portion at the tip of the engagement portion-equipped bolt so as to be able to advance and retreat in the axial direction and engage with the tool engagement portion , the inner member having an engaged hole having a shape corresponding to the tool engagement portion ;
a control unit that automatically switches the rotational speed of the power tool so as to rotate a rotating shaft of the power tool at a first rotational speed for a predetermined time, screw in the bolt with engagement portion to engage the tip of the bolt with engagement portion with the tip of the inner member, and after the predetermined time has elapsed, screw in the bolt with engagement portion at a second rotational speed faster than the first rotational speed to fasten the fastened members. 3. The fastening tool for a bolt with an engaging portion according to claim 2, wherein the inner member has an engaged hole that supports the tool engaging portion of the bolt with an engaging portion so that the tool engaging portion can advance and retreat in the axial direction. The tightening tool for a bolt with an engaging portion as described in claim 2 or 3, characterized in that the engaged hole at the tip of the inner member is polygonal in shape, and each side of the inner surface of the engaged hole is formed with an inclined portion to promote the introduction of the second engaging portion of the bolt with an engaging portion. The tightening tool for a bolt with an engagement portion as described in claim 2 or 3, characterized in that the outer member is arranged on the power tool with a radial gap from the rotating shaft, and has a leg portion whose base end side is fixed to the main body of the power tool.