JP7658720B2 - Torque Control Tool - Google Patents

Description

The present invention relates to a tightening torque management tool for tightening fasteners such as nuts or bolts to a required torque, and to a combination of such a tightening torque management tool and a fastener.

For example, in the installation of sound insulation walls on expressways, the installation of ceiling walls of tunnels, and the installation of various parts in various buildings, as is well known, bolt and nut fastenings are widely used. In such fastenings, it is important to tighten the nut (usually a locking nut) to the bolt with a relatively large required torque, for example, about 17 to 24 Nm for a hexagonal nut with a nominal diameter of M10, and about 250 to 360 Nm for a hexagonal nut with a nominal diameter of M24. The following Patent Document 1 discloses a tightening torque management tool that can be used when tightening a nut to a bolt or a bolt to a nut with the required torque. Such a tightening torque management tool is integrally formed from a synthetic resin, and has an inner peripheral surface that defines a storage hole with an open lower end surface, and an outer peripheral surface that is similar in shape to the outer peripheral surface of the torque application regular polygon of the fastener, and the inner peripheral surface that defines the storage hole has a shape in which recesses are partially formed on each side of the regular polygon surface that corresponds to the outer peripheral surface of the torque application polygon of the fastener, and when the fastener is stored at least partially in the storage hole and tightening torque is applied to the outer peripheral surface, if the tightening torque exceeds a threshold value, the inner peripheral surface of the storage hole is partially deformed and the fastener will spin freely relative to the fastener.

JP 2019-209382 A

As described above, in the conventional tightening torque management tool, when the threshold of the tightening torque to be managed is large, particularly when the threshold of the tightening torque to be managed is large, when the tightening torque exceeds the threshold and the inner surface of the storage hole is partially deformed, a part of the tightening torque management tool tends to be torn off and fall as debris. As described in the specification and drawings of Patent Application No. 2019-046850 applied by the present applicant, in order to prevent the outer peripheral surface of the tightening torque management tool from being plastically deformed and biting into the inner peripheral surface of the socket of the fastener, it is desirable to form a through opening that penetrates from the bottom surface of the recess to the outer peripheral surface at a required portion of the recess on the inner peripheral surface, or to form a recessed portion in the area corresponding to the recess on the outer peripheral surface, but when such a through opening or recessed portion is formed, there is a noticeable tendency for a part of the tightening torque management tool to be torn off and fall as debris.

The present invention was made in consideration of the above facts, and its main technical objective is to provide a new and improved tightening torque management tool that prevents as much as possible a part of the tightening torque management tool from being torn off and falling as debris when the tightening torque exceeds a threshold value and the inner surface of the storage hole is partially deformed.

After extensive research and experimentation, the inventors have discovered that the above-mentioned main technical objective can be achieved by setting at least a portion of the downstream side surface, which is located downstream in the tightening rotation direction of the recess, to form an obtuse angle α with the edge surface.

That is, according to the present invention, as a tightening torque management tool that achieves the above-mentioned main technical object,
A tightening torque management device which is formed integrally from a synthetic resin, has an inner peripheral surface which defines a storage hole with an open lower end surface, and an outer peripheral surface which is similar in shape to the outer peripheral surface of a torque application regular polygon of a fastener, and the inner peripheral surface which defines the storage hole has a form in which recesses are partially formed on each side surface of the regular polygon which corresponds to the outer peripheral surface of the torque application polygon of the fastener, and when a fastener is at least partially stored in the storage hole and a tightening torque is applied to the outer peripheral surface, if the tightening torque exceeds a threshold value, the inner peripheral surface of the storage hole is partially deformed, causing the fastener to spin freely relative to the fastener.
The recess has a bottom surface formed on the inner circumferential surface, and an upstream side surface and a downstream side surface located on the upstream side and the downstream side, respectively, as viewed in the fastening rotation direction,
A torque management tool is provided, characterized in that the entire downstream side surface of the recess forms an obtuse angle α with the side surface.

In this specification and claims, "the angle that the downstream side of the recess makes with respect to the edge surface" means the angle that the downstream side of the recess makes with respect to the edge surface on the downstream side as viewed in the tightening rotation direction.

The angle α is preferably 110 to 130 degrees. It is convenient for each of the side surfaces of the receiving hole to be angularly aligned with each of the side surfaces of the outer circumferential surface. In a preferred embodiment, a through opening is formed in the bottom surface of the recess, penetrating from the bottom surface to the outer circumferential surface. In this case, the through opening is preferably rectangular. It is also convenient for the through opening to exist over the entire circumferential direction of the recess. In another preferred embodiment, a recess is formed in the outer circumferential surface in a region corresponding to the recess of the inner circumferential surface. In this case, the recess is preferably rectangular. It is also convenient for the recess to exist over the entire circumferential direction of the recess. In a typical form, the torque-adding regular polygon outer circumferential surface of the fastener is a regular hexagon.

The present invention further provides a combination of the tightening torque management tool as described above and a fastener at least partially accommodated in the accommodation hole of the tightening torque management tool. Preferably, the fastener is press-fitted into the accommodation hole. In a typical embodiment, the fastener is a hexagonal nut.

According to the tightening torque management tool of the present invention, the entire downstream side of the recess forms an obtuse angle α with respect to the edge surface, so that when the tightening torque exceeds a threshold value, the deformation of the inner surface of the tightening torque management tool proceeds in a manner that gradually washes away the material, thereby preventing localized tearing of the material as much as possible.

1 is a perspective view of a preferred embodiment of a tightening torque management tool constructed according to the present invention, seen from above. FIG. FIG. 2 is a front view of the tightening torque management tool shown in FIG. 1 . FIG. 2 is a cross-sectional view of the tightening torque management tool shown in FIG. 1 . FIG. 2 is a plan view of the tightening torque management tool shown in FIG. 1 . FIG. 2 is a bottom view of the tightening torque management tool shown in FIG. 1 . FIG. 2 is a cross-sectional view showing a combination of the tightening torque management tool shown in FIG. 1 and a nut, which is a typical example of a fastener. FIG. 7 is a bottom view of the combination shown in FIG. 6 . 8 is a bottom view showing the state after the tightening torque management tool rotates freely relative to the nut due to the tightening torque of the nut exceeding the threshold value in the combination shown in FIG. 6 and FIG. 7 . FIG. 4 is a bottom view showing a reference example of a tightening torque management tool. FIG. 11 is a perspective view of another modified example of the tightening torque management tool constructed in accordance with the present invention, viewed from above.

The present invention will be described in further detail below with reference to the attached drawings showing a preferred embodiment of a tightening torque management tool constructed in accordance with the present invention and a combination of such an embodiment with a nut, which is a typical example of a fastener.

Referring to Figures 1 to 3, the tightening torque management tool generally designated by the number 2 is integrally formed by injection molding or compression molding from an appropriate synthetic resin, preferably a relatively high-strength synthetic resin such as polycarbonate or acrylonitrile butadiene styrene (ABS). Such a tightening torque management tool 2 is generally cylindrical in shape, and has an inner circumferential surface 6 that defines a storage hole 4 with an open lower end face, and an outer circumferential surface 8 that is similar in shape to the torque application regular polygon outer circumferential surface of the tightening tool.

Continuing the explanation with reference to Figures 1 to 3 as well as Figures 4 and 5, it is important that the inner peripheral surface 6 defining the storage hole 4 has a shape in which recesses 12 are partially formed on each side surface 10 of an imaginary regular polygon inner peripheral surface corresponding to the torque application regular polygon outer peripheral surface of the fastener to be stored. In the illustrated embodiment, the fastener is a hexagonal nut as described later, and therefore the torque application regular polygon outer peripheral surface of the fastener is a regular hexagon, and the imaginary regular polygon inner peripheral surface (the inner peripheral surface shown by the two-dot chain line in Figure 5) is also a regular hexagon. Each recess 12 formed in the center of each side surface 10 has a bottom surface 12a and both side surfaces, that is, an upstream side surface 12b located on the upstream side as viewed in the tightening rotation direction (clockwise in Figure 4, counterclockwise in Figure 5) and a downstream side surface 12c located on the downstream side. In the illustrated embodiment, the bottom surface 12a is an arc shape forming a part of a circle centered on the center of the storage hole 4. The upstream side surface 12b extends in an arc shape inclined outward from the side surface 10 in the tightening rotation direction. On the other hand, the downstream side surface 12c extends in a straight line inclined outward from the side surface 10 in the opposite direction to the tightening rotation direction. It is important that the entire downstream side surface 12c forms an obtuse angle α with the side surface 10, preferably 110 degrees to 130 degrees. The angle α means the angle that the downstream side surface 12c forms with the side surface 10 on the downstream side as viewed in the tightening rotation direction, as shown in Figure 5. In the present invention , the entire downstream side surface 12c forms an obtuse angle α with the side surface 10, but the radially inner part of the downstream side surface 12c can be substantially perpendicular to the side surface 10, for example, as in a reference example described later. It is advantageous that the circumferential length L1 of the side face 10a downstream of the recess 12 in the above-mentioned fastening rotation direction is longer than the circumferential length L2 of the side face 10b upstream of the recess 12 (as will be clearly understood from the explanation below, the threshold value of the fastening torque is determined by the deformation of the side face 10a downstream of the recess 12).

It is preferable that a retaining protrusion is provided on the portion 10b of the side surface 10 that defines the inner peripheral surface of the storage hole 4 and is located upstream of the recess 12 when viewed in the tightening rotation direction (clockwise in FIG. 4, counterclockwise in FIG. 5). In the illustrated embodiment, the retaining protrusion is composed of a rib 14 that extends in the axial direction of the storage hole 4 (up and down in FIG. 3, perpendicular to the paper surface in FIG. 5), preferably substantially parallel to the axis of the storage hole 4. In the illustrated embodiment, a retaining protrusion, i.e., a rib 14, is formed on each of the portions 10b of the six side surfaces 10. As can be clearly understood by referring to FIG. 3, each of the ribs 14 extends substantially parallel to the axis of the storage hole 4 from the upper end to the vicinity of the lower end of the storage hole 4. The protruding height H of the rib 14 is about 0.1 to 0.5 mm, and the circumferential width W of each of the ribs 14 is preferably about 0.1 to 0.5 mm. The cross-sectional shape of the protruding end of the rib 14 is preferably semicircular as shown in FIG. 5. In the illustrated embodiment, the ribs 14 are formed on all of the upstream portions 10b of the six side faces 10, but if desired, the ribs 14 can be formed on only three side faces 10 located every other side face 10 or two side faces 10 located diametrically opposite each other. Alternatively, a plurality of ribs can be formed on each side face 10 at intervals in the axial direction and/or in the circumferential direction.

The rib 14 constituting the holding protrusion can be formed not only on the portion 10b of the side surface 10 located upstream of the recess 12 as viewed in the tightening rotation direction, but also on the portion 10a of the side surface 10 located downstream of the recess 12 as viewed in the tightening rotation direction. However, if the rib 14 is also formed on the portion 10a of the side surface 10 located downstream of the recess 12 as viewed in the tightening rotation direction, as described below, when the tightening torque reaches the threshold value, the portion 10a of the side surface 10 located downstream of the recess 12 as viewed in the tightening rotation direction is mainly deformed, so that the rib 14 is deformed over its entirety before the deformation of the side surface 10, and as a result, the tightening torque management tool 2 tends to come off the fastener before the tightening torque reaches the threshold value. Therefore, it is preferable not to provide the rib 14 on the portion 10a of the side surface 10 located downstream of the recess 12 as viewed in the tightening rotation direction.

In the illustrated embodiment, the upper end of the tightening torque management tool 2 is formed with a circular protrusion 16 extending radially inward, and further, a circular inner flange portion 18 is formed extending radially inward from the upper end of the protrusion 16. Therefore, at the upper end of the inner peripheral surface 6 that defines the storage hole 4, there is an annular shoulder surface 20 defined by the lower surface of the protrusion 16 and an annular shoulder surface 22 defined by the lower surface of the inner flange portion 18, and at the upper end of the inner peripheral surface 6, there is a circular through opening 24 defined by the inner peripheral surface of the inner flange portion 18 (see FIG. 3). On the other hand, at the lower end of the tightening torque management tool 2, a circular outer flange portion 26 extending radially outward is formed. As can be understood from FIGS. 4 and 5, the outer peripheral surface of the outer flange 26 is a deformed hexagonal shape defined by a convex arc shape and a concave arc shape. The main portion of the upper surface of the tightening torque management tool 2 (including the upper surface of the inner flange portion 20) may be a substantially horizontal plane, and each of the hexagonal corners is slightly inclined downward toward the radial outward direction, and a reinforcing rib 28 extending in the radial direction is formed at each of the corners. The lower surface of the tightening torque management tool 2 (including the lower surface of the outer flange portion 26) may also be a substantially horizontal plane. The lower end of the inner peripheral surface of the storage hole 4 is chamfered.

Continuing the explanation with reference to Figures 1 to 5, the outer peripheral surface 8 is a similar shape to the torque-applying regular polygonal outer peripheral surface of the fastener, as described above. In the illustrated embodiment, the fastener is a hexagonal nut, as described below, and therefore the outer peripheral surface 8 is a regular hexagon, the size of which is preferably about 1.2 to 1.6 times the torque-applying regular polygon of the fastener. Each of the side surfaces 10 in the storage hole 4 and each of the side surfaces 30 in the outer peripheral surface 8 are preferably angularly aligned. As described below, when the torque applied to the outer circumferential surface 8 exceeds a threshold value while the fastener is stored in the storage hole 4, the inner circumferential surface 6 that defines the storage hole 4 deforms. In order to reliably prevent cracks from being generated from the inner circumferential surface 6 to the outer circumferential surface 8, which would damage the entire torque management tool 2, it is desirable that the length X1 (Figure 5) between diametrically opposed corners (intersection points of side surfaces 10 and 10) on the inner circumferential surface 6 is smaller than the length X2 (Figure 4) between diametrically opposed side surfaces 30 on the outer circumferential surface 8.

In the illustrated embodiment, as can be clearly understood by referring to Figs. 1 to 3, a through opening 32 is formed penetrating from the bottom surface 12a of the recess 12 arranged in the center of each side surface 10 to the outer peripheral surface 8. The through opening 32 is formed over substantially the entire circumferential area of the bottom surface 12a of the recess 12, and is a rectangular shape that extends in an elongated manner in the axial direction from the lower end to the vicinity of the upper end of the recess 12. The through opening 32 does not necessarily have to extend from the lower end to the upper end of the recess 12, and can be formed in a part of the axial direction of the recess 12, but as will be further mentioned later, when the tightening torque management tool 2 is actually used, plastic deformation tends to be generated in the axial lower part of the recess 12, so it is preferable that the through opening 32 is formed at least in the axial lower part of the recess 12. If desired, instead of the rectangular through opening 32, a through opening of an appropriate shape, such as a triangular or trapezoidal shape whose circumferential width gradually decreases toward the axial upward direction, can be formed. In the illustrated embodiment, a notch 34 is further formed on the inner peripheral edge of the outer flange portion 24, which continues to the through opening 32 (see Figures 1 and 4). In the illustrated embodiment, it extends over substantially the entire width of the bottom surface 12a of the recess 12, and therefore the upstream wall 12b of the recess 12 is continuous with the upstream side wall of the through opening 32, and the downstream wall 12c of the recess 12 is continuous with the downstream side wall of the through opening 32. In such a configuration, the "downstream wall of the recess" in this specification and claims includes not only the downstream wall 12c of the recess 12 but also the downstream wall of the through opening 32, and the downstream wall of the through opening 32 constitutes the radially outer portion of the downstream wall 12c of the recess 12.

The tightening torque management tool 2 as described above can be distributed on the market by itself, but it is more convenient to distribute it on the market in combination with a fastener as shown in Figures 6 and 7 (in Figure 7, the rib 14 is elastically or plastically deformed by pressing the fastener, i.e., the hexagonal nut 36, into the storage hole 4, but such deformation is not shown and the rib 14 is shown superimposed on the hexagonal nut 36 in an undeformed state). In the embodiment shown in Figures 6 and 7, a locking hexagonal nut 36 is shown as a typical example of a fastener. The outer peripheral surface 38 of the hexagonal nut 36 is a regular hexagon, and if the manufacturing error of the hexagonal nut 36 is sufficiently small, it is slightly larger than the above-mentioned virtual regular hexagon for the storage hole 4 formed in the tightening torque fastener 2 (in other words, the virtual regular hexagon of the storage hole 4 in the tightening torque management tool 2 is set to be smaller than the outer peripheral surface 38, which is a regular hexagon, of the hexagonal nut 36). Then, the main portion of the hexagonal nut 36, i.e., the portion excluding the lower end portion, is press-fitted into the storage hole 4. The annular portion 40 formed on the upper surface of the hexagonal nut 36 is housed in the space defined by the inner peripheral surface of the protrusion 16, and its upper edge abuts against the annular shoulder surface 22 defined by the lower surface of the flange portion 18. The hexagonal nut 36 is held in the storage hole 4 by the rib 14 being pressed against the outer peripheral surface 38 of the hexagonal nut 36 together with the portion 10a located downstream of the recess 12 when viewed in the tightening rotation direction (clockwise in FIG. 4, counterclockwise in FIG. 5). Thus, the manufacturing tolerance of the tightening torque management tool 2, which is injection molded or compression molded from an appropriate synthetic resin, is relatively small, and therefore the manufacturing error of the inner peripheral surface of the storage hole 4 is relatively small, whereas the manufacturing tolerance of the hexagonal nut 36 is relatively large, and therefore the manufacturing error of the outer peripheral surface 38 of the hexagonal nut 36 is relatively large. However, the relatively large manufacturing error of the outer peripheral surface 38 of the hexagonal nut 36 relative to the inner peripheral surface of the storage hole 4 is compensated for by the elastic or plastic deformation of the rib 14 formed on the required portion of the inner peripheral surface of the storage hole 4. Therefore, it is possible to avoid as much as possible the force required to press the hexagonal bolt 36 into the storage hole 4 being too large or too small.

The usage of the tightening torque management tool 2 as described above will be explained. If the hexagonal nut 36 is already combined with the tightening torque management tool 2, the hexagonal nut 36 is fitted onto the shaft 42 (FIG. 6) of the bolt to be tightened (if the hexagonal nut 36 is not combined with the tightening torque management tool 2, the hexagonal nut 36 provisionally fastened to the bolt is stored in the storage hole 4 of the tightening torque management tool 2). Next, as shown by the two-dot chain line in FIG. 6, the socket 44 of the automatic or manual tightening tool (the inner peripheral surface of the socket 44 is a hexagonal cylindrical shape corresponding to the outer peripheral surface of the tightening torque management tool 2) is fitted onto the outer peripheral surface 8 of the tightening torque management tool 2. At this time, the lower end of the socket 44 is abutted against the upper surface of the outer flange portion 26 of the tightening torque management tool 2, so that the socket 44 can be easily positioned as required relative to the tightening torque management tool 2. Then, the fastener socket 44 is rotated in the fastening direction (clockwise in FIG. 4, counterclockwise in FIG. 5). The torque applied to the tightening torque management tool 2 from the socket 44 is transmitted to the hexagonal nut 36, which tightens the hexagonal nut 36 onto the bolt shaft 42. When the hexagonal nut 36 advances over a relatively long distance in the axial direction relative to the bolt shaft 42, the bolt shaft 42 moves upward through the through hole 24 defined by the inner flange portion 18 of the tightening torque management tool 2, as shown by the two-dot chain line in FIG. 6.

When the tightening torque transmitted to the hexagonal nut 36 exceeds a predetermined threshold, as shown in Fig. 8, the inner peripheral surface of the storage hole 4, particularly the portion 10a downstream of the recess 12 as viewed in the tightening rotation direction, is pressed toward the opposite side of the tightening rotation direction and deformed, causing the tightening torque management tool 2 to rotate freely relative to the hexagonal nut 36, and thus the hexagonal nut 36 is fastened to the bolt with the required tightening torque. The entire downstream side surface 12c located downstream as viewed in the tightening rotation direction in the recess 12 forms an obtuse angle α with the side surface 10, so that the deformation of the inner peripheral surface 6 of the tightening torque management tool 2 when the tightening torque exceeds the threshold proceeds in a manner that gradually sweeps away the material, and localized tearing of the material is prevented as much as possible. On the other hand, when the tightening torque management tool 2 starts to rotate idly relative to the hexagonal nut 36, the outer peripheral corner of the hexagonal nut 36 may collide violently with the upstream side 12b of the recess 12 of the storage hole 4. However, in the illustrated embodiment, the upstream side 12b extends in an arc shape inclined outward in the tightening rotation direction relative to the side surface 10, so that the force applied from the outer peripheral corner of the hexagonal nut 36 to the upstream side 12b of the recess 12 is appropriately buffered or eliminated. In addition, the socket 44 fitted onto the outer peripheral surface 8 of the tightening torque management tool 2 functions as a reinforcing member of the tightening torque management tool 2. Thus, cracks are generated in the tightening torque management tool 2 or the tightening torque management tool 2 is prevented from being damaged as much as possible. When the inner peripheral surface 6 of the storage hole 4 of the tightening torque management tool 2 is deformed as described above, the outer peripheral surface 8 is also deformed, but the deformation of the outer peripheral surface 8 is generated intensively in a portion with low deformation resistance, that is, in the illustrated tightening torque management tool 2, the portion defining the downstream side of the through opening 32 as viewed in the tightening rotation direction is deformed toward the opposite side of the tightening rotation direction, and the width of the through opening 32 is reduced. According to the experience of the present inventors, the reduction in the width of the through opening 32 occurs mainly in the axial lower portion of the through opening 32, in other words, the deformation of the outer peripheral surface 8 occurs mainly in correspondence with the axial lower portion of the through opening 32. Therefore, it is preferable that the through opening 32 is formed at least axially below the recess 12. The tendency of the outer peripheral surface 8 to spread radially outward is sufficiently suppressed by the outer peripheral surface 8 deforming in the circumferential direction due to the presence of the through openings 32, and the deformation of the outer peripheral surface 8 is generated in a concentrated manner in the area where the through openings 32 are formed, so that the outer peripheral surface 8 is prevented from biting into the inner peripheral surface of the fastener socket 44. Therefore, after the tightening torque management tool 2 begins to rotate freely relative to the hexagonal nut 36, it is tightened to the bolt shaft 42 with the required tightening torque, and the tightening torque management tool 2 can be sufficiently easily removed from the hexagonal nut 36.

9 illustrates a reference example of the tightening torque management tool 2. In the reference example illustrated in FIG. 9, the radially outer portion 12c-2 of the downstream side surface 12c of the recess 12 and the downstream side surface 32c of the through opening 32 following this form an obtuse angle α with respect to the side surface 10, but the radially inner portion 12c-1 of the downstream side surface 12c extends substantially perpendicular to the side surface 10. Even when the downstream side surface 12c has such a shape, the deformation of the inner peripheral surface 6 of the tightening torque management tool 2 when the tightening torque exceeds the threshold value proceeds in a manner that gradually sweeps away the material, and localized tearing of the material is prevented as much as possible. As described above, when the through opening 32 extends substantially across the circumferential front width of the recess 12, the downstream side surface 32c of the through opening 32 is also included in the downstream side surface 12c of the recess 12, and if desired, the downstream side surface 12c-2 can also extend substantially perpendicular to the side surface 10 like the downstream side surface 12c-1, and only the downstream side surface 32c can form an obtuse angle α with the side surface 10. The configuration of the modified example shown in Figure 9 other than the above-mentioned configuration (downstream side surface 12c) is substantially the same as the embodiment shown in Figures 1 to 8.

Figure 10 illustrates yet another modified example of the tightening torque management tool 2 constructed according to the present invention. In the modified example illustrated in Figure 10, instead of the through opening 32 in the tightening torque management tool 2 described above, a recessed portion 46 is formed in the region corresponding to the recess 12 (see Figure 5) on the outer peripheral surface 8 (i.e., the portion where the through opening 32 is formed in the tightening torque management tool 2 described above), thereby locally reducing the wall thickness. As in the case of the through opening 32 in the tightening torque management tool 2 described above, the recessed portion 46 is located over substantially the entire circumferential area of the bottom surface 12a of the corresponding recess 12, and has a rectangular shape that extends in an axial direction from the lower end to the upper end of the recess 12 (see also Figure 5). The recessed portion 46 does not necessarily need to extend from the lower end to the upper end of the recess 12, and can be formed to correspond to a part of the axial direction of the recess 12. However, since plastic deformation tends to occur in the axial lower portion of the recess 12 when the tightening torque management tool 2 is actually used, it is preferable that the recessed portion 46 is formed to correspond to at least the axial lower portion of the recess 12. If desired, instead of the rectangular recessed portion 46, a recessed portion of an appropriate shape, such as a triangular or trapezoidal shape whose circumferential width gradually decreases toward the axial upper portion, can be formed. The configuration of the modified example shown in FIG. 10 other than the above-mentioned configuration (i.e., the recessed portion 46) is substantially the same as the embodiment shown in FIGS. 1 to 8.

2: Tightening torque control tool 4: Storage hole 6: Inner peripheral surface 8: Outer peripheral surface 10: Side surface 12: Recess 12a: Bottom surface 12b: Upstream side surface 12c: Downstream side surface 32: Through opening 36: Hexagonal nut 46: Recessed portion

Claims (13)

A tightening torque management device which is formed integrally from a synthetic resin, has an inner peripheral surface which defines a storage hole with an open lower end surface, and an outer peripheral surface which is similar in shape to the outer peripheral surface of a torque application regular polygon of a fastener, and the inner peripheral surface which defines the storage hole has a form in which recesses are partially formed on each side surface of the regular polygon which corresponds to the outer peripheral surface of the torque application polygon of the fastener, and when a fastener is at least partially stored in the storage hole and a tightening torque is applied to the outer peripheral surface, if the tightening torque exceeds a threshold value, the inner peripheral surface of the storage hole is partially deformed, causing the fastener to spin freely relative to the fastener.
The recess has a bottom surface formed on the inner circumferential surface, and an upstream side surface and a downstream side surface located on the upstream side and the downstream side, respectively, as viewed in the fastening rotation direction,
A torque management tool characterized in that the entire downstream side surface of the recess forms an obtuse angle α with the edge surface. The fastening torque management tool according to claim 1, wherein the angle α is between 110 and 130 degrees. The tightening torque management tool according to claim 1 or 2, wherein each of the side surfaces of the storage hole is angularly aligned with each of the side surfaces of the outer circumferential surface. The fastening torque management tool according to any one of claims 1 to 3, wherein a through opening is formed in the bottom surface of the recess, penetrating from the bottom surface to the outer peripheral surface. The fastening torque management tool according to claim 4 , wherein the through opening is rectangular. The fastening torque management tool according to claim 4 or 5 , wherein the through opening is present over the entire circumferential direction of the recess. The fastening torque management tool according to any one of claims 1 to 3, in which a recess is formed in the area of the outer circumferential surface that corresponds to the recess of the inner circumferential surface. The fastening torque management tool according to claim 7 , wherein the recess is rectangular. The fastening torque management tool according to claim 7 or 8 , wherein the recess exists over the entire circumferential direction of the recess. The tightening torque management tool according to any one of claims 1 to 9 , wherein the torque application regular polygon outer peripheral surface of the fastener is a regular hexagon. A combination of a tightening torque management tool according to any one of claims 1 to 10 and a fastener at least partially housed in the housing hole of the tightening torque management tool. 12. The combination of claim 11 , wherein said fastener is press fit into said receiving hole. 13. The combination of claim 11 or 12 , wherein the fastener is a hex nut.