JP2024006123A - clinching stud bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clinching stud bolt which can be improved in quality when fixed to an attachment objective plate material.

SOLUTION: A clinching stud bolt B which is fixed to an attachment objective plate material T in a retention state and in a whirl-stop state, comprises: a head part 1; a screw shaft part 2; a whirl-stop part 3; an annular groove part 21; and an annular protrusion 22. The attachment objective plate material T is constituted so as to be sandwiched between a seat face 21 of the head part 1 and the annular protrusion 22, and a recessed part 32 recessed toward an upper side X2 in a spiral direction is formed at the whirl-stop part 3. An outside edge part 31 of the whirl-stop part has round corner parts 31 being a plurality of radially-arranged apexes, a plurality of connection sides 32b for connecting a pair of the round corner parts, and recessively formed inside a radial direction, and a trough part 31c being a portion located at a side nearest the inside in the radial direction out of the connection sides. A height of the trough part is set lower than those of the round corner parts, and the connection sides are constituted so as to connect the trough part and the round corner parts.

SELECTED DRAWING: Figure 8

COPYRIGHT: (C)2024,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a clinching stud bolt that is fixed to a plate material to which it is attached in a non-slip and non-rotating state.

Conventionally, clinching stud bolts (clinch studs) are known that are press-fitted into the mounting holes of metal plates (plates to be attached) and are fixed in a non-slip and non-rotating state (for example, see Patent Document 1). ). This clinching stud bolt includes a head and a threaded shaft extending from the seat surface of the head. When fixing another member to a metal plate material, insert the screw shaft into the through hole of this separate member, screw the nut so that it moves in the opposite direction to the direction in which the screw shaft extends, and then connect the nut to the metal plate. A separate member is inserted between the board and the plate to secure it.

The clinching stud bolt described in Patent Document 1 has a non-circular detent portion (a detent protrusion in the document) that bulges from the seating surface toward the lower side in the screw direction of the screw shaft portion, and a screw shaft portion. An annular groove (retaining groove in the literature) that is recessed in an annular shape toward the inside in the radial direction of ). The technique described in Patent Document 1 is to provide a protrusion that protrudes on the side facing the head around the mounting hole of the metal plate material, so that when the clinching stud bolt is press-fitted into the metal plate material, the protrusion part rotates. It is crushed by the stop protrusion and pushes a large amount of metal into the retaining groove, increasing the pullout load and idling torque.

Japanese Patent Application Publication No. 2014-141999

However, in the clinching stud bolt described in Patent Document 1, the metal that is crushed by the detent projection and flows protrudes from the periphery of the mounting hole located on the opposite side of the head to the radial outside of the retaining ring. It is easy to get burrs. In addition, the metal crushed by the detent projection flows to the outside in the radial direction of the detent projection and is deformed, which tends to cause warping of the metal plate material. As a result, when fixing another component to a metal plate, inconveniences occur such as the burr damaging the other component, the burr becoming a foreign object and scattering around, and the warped metal plate interfering with surrounding parts. Product quality deteriorates.

Therefore, there is a need for a clinching stud bolt that can improve the quality when fixed to the plate material to which it is attached.

a head; a screw shaft extending from a seat surface of the head; a rotation stopper that bulges toward the lower side in the direction of advancement, and a radially inner side of the screw shaft at a position adjacent to the rotation stopper on the lower side in the screw movement direction of the screw shaft. an annular groove recessed in an annular shape toward the screw shaft; and an annular groove recessed toward the outside in the radial direction of the screw shaft at a position adjacent to the annular groove on the downward side of the screw shaft with respect to the annular groove. a protruding annular protrusion, the mounting target plate material is sandwiched between the seat surface and the annular protrusion, and the rotation stopper is provided with an annular protrusion that extends upwardly in the spiral direction. A clinching stud bolt that is fixed to a plate material to be attached in a non-slip and non-rotating state by forming a recessed part, wherein an outer edge of the non-rotating part is arranged radially. a plurality of rounded corners that form a plurality of vertices, a plurality of connecting sides that are concavely formed radially inward to connect the pair of rounded corners, and a trough that is the most radially innermost part of the connecting sides. The height of the valley portion is set lower than the round corner portion, and the connection side is formed by a clinching stud bolt configured to connect the valley portion and the round corner portion.

According to the clinching stud of the present invention, since the height of the trough of the detent part is low, even if the outer diameter of the head is made small, the trough of the detent part remains close to the screw axis. In other words, since the predetermined gap can be secured between the trough of the rotation stopper and the screw shaft, the plate material to be mounted that has been crushed by the rotation stopper is not obstructed by the recessed part. It will flow to

It is a perspective view of a clinching stud bolt. It is a side view of a clinching stud bolt. FIG. 3 is a view taken along the line III-III in FIG. 2; 4 is a sectional view taken along the line IV-IV in FIG. 3. FIG. FIG. 6 is an enlarged cross-sectional view at a position where the convex portion is farthest from the annular protrusion. FIG. 7 is an enlarged cross-sectional view at a position where the convex portion is closest to the annular protrusion. FIG. 3 is a cross-sectional view of the clinching stud bolt before it is press-fitted into the plate material to be attached. It is a sectional view after the clinching stud bolt is press-fitted into the plate material to be attached.

EMBODIMENT OF THE INVENTION Below, embodiment of the clinching stud bolt based on this invention is described based on drawings. In this embodiment, a clinching stud bolt that is press-fitted into a metal plate as an attachment target plate will be described as an example. However, the present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist thereof.

As shown in FIGS. 1 and 2, the clinching stud bolt B has a flat cylindrical head 1 with rounded edges along the circumferential direction, and a head 1 extending from a seat surface 11 of the head 1. The screw shaft portion 2 is provided. A male threaded portion 2A is formed in most of the screw shaft portion 2, and the spiraling direction X of the screw shaft portion 2 coincides with the direction in which the screw shaft portion 2 extends. The threading direction X means the direction in which the clinching stud bolt B moves forward with respect to the female thread when the male threaded portion 2A of the screw shaft portion 2 is screwed into the female thread (not shown). Hereinafter, the distal end side of the screw shaft portion 2 will be referred to as the lower side in the screw direction X1, and the base end side of the screw shaft portion 2 (the connection side between the head 1 and the screw shaft portion 2) will be referred to as the upper side in the screw direction X2. .

As shown in FIG. 8, the clinching stud bolt B is fixed to the metal plate T in a manner that prevents it from slipping out and prevents rotation, so that the male threaded portion 2A of the screw shaft portion 2 protrudes from the metal plate T. By removing the tool G, it is exposed to the outside. The clinching stud bolt B is made of a metal material such as low carbon steel that has higher rigidity than the metal plate T. The clinching stud bolt B is press-fitted into the metal plate T by a hydraulic press P, and the metal plate T is pressed. be crushed. As a result, the metal plate T is sandwiched between the seat surface 11 of the head 1 and an annular protrusion 22, which will be described later.

As shown in FIGS. 1 and 2, the clinching stud bolt B has a detent portion 3 that bulges out from the seat surface 11 of the head 1 toward the lower side X1 in the screw direction, and a radial direction of the screw shaft portion 2. It includes an annular groove portion 21 that is recessed in an annular shape toward the inside, and an annular protrusion 22 that projects in an annular shape toward the outside in the radial direction of the screw shaft portion 2. The annular groove 21 is located in the screw shaft 2 adjacent to the rotation stopper 3 on the lower side X1 in the screw direction, and the annular protrusion 22 is located in the screw shaft 2 adjacent to the rotation stopper 3 on the lower side X1 in the screw direction. It is located adjacent to the lower side X1 in the spiral direction. That is, the rotation stopper 3, the annular groove 21, and the annular protrusion 22 are arranged in this order along the spiral direction X.

The groove width of the annular groove 21 is set according to the shape of the annular protrusion 22 and the ductility of the metal plate T, and in this embodiment, it is set to be equal to the thickness of the metal plate T (see also FIG. reference). The annular groove portion 21 and the annular protrusion 22 are continuous in an R shape, and the annular protrusion 22 and the male thread portion 2A are continuous in a tapered shape (see also FIG. 4). The annular groove portion 21 in this embodiment has an outer diameter smaller than the outer diameter of the male thread portion 2A formed on the screw shaft portion 2, and the annular protrusion 22 has an outer diameter smaller than the outer diameter of the male thread portion 2A formed on the screw shaft portion 2. It has an outer diameter larger than the outer diameter of 2A. Further, the diameter of the annular protrusion 22 in this embodiment is set smaller than the diameter of the through hole Ta of the metal plate T (see also FIG. 7).

As shown in FIG. 3, the rotation preventing portion 3 is formed in a six-pointed star shape (an example of a non-perfect circular shape) surrounding the screw shaft portion 2 when viewed in the screw direction X. The outer edge 31 of the rotation stopper 3 is concave in the radial direction connecting a plurality of radially arranged rounded corners 31a (six in this embodiment) that serve as vertices and a pair of rounded corners 31a. It has a plurality of (six in this embodiment) connecting sides 31b formed therein, and a valley portion 31c that is the most radially inward portion of the connecting sides 31b. The circumscribed circles of the plurality of rounded corners 31a have a diameter equivalent to that of the outer peripheral edge 11a of the seat surface 11. By making the rounded corner part 31a into a tipped shape, the detent part 3 in this embodiment can bring the connecting side 31b as far as possible to the outside in the radial direction, compared to the case where the rounded corner part 31a has a bulged semicircular shape. This makes it possible to increase the volume of the recessed portion 32, which will be described later. Due to the shape of the rotation stopper 3, when the rotation stopper 3 is press-fitted into the metal plate T, the clinching stud bolt B is prevented from rotating relative to the metal plate T. Further, the height of the trough portion 31c of the detent portion is set lower than the rounded corner portion, and the connecting side 31b is configured to connect the trough portion 31c and the rounded corner portion 31a. Therefore, even if the outer diameter of the head 1 is made small, the trough 31c of the rotation stopper 3 does not come too close to the screw shaft 2; Since a predetermined gap can be secured between them, the metal plate T crushed by the rotation stopper 3 can flow into the recessed part 32 without being hindered.

As shown in FIG. 4, the detent portion 3 is formed with a recessed portion 32 that is recessed in an annular shape toward the upper side X2 in the screwing direction (see also FIG. 1). This recessed portion 32 forms a convex portion 31A on the outer edge 31 of the rotation stopper 3 that protrudes toward the lower side X1 in the spiral direction. This convex portion 31A is formed at the same height over the entire area. When the metal of the metal plate T enters the recessed portion 32 and the annular groove 21, the clinching stud bolt B is prevented from coming off and rotating relative to the metal plate T. The volumes of the recessed part 32 and the annular groove 21 that accommodate the metal of the metal plate T are set according to the volume and ductility of the metal plate T that flows when the convex part 31A is crushed and plastically deformed ( (See also Figure 8). The inner edge 32a of the recessed part 32 reaches the annular groove 21 of the screw shaft part 2 and is continuous with the annular groove 21 in an R shape, and the outer edge 32b of the recessed part 32 reaches the most protruding part of the convex part 31A. It reaches the end 31Aa (the outer edge 31 of the rotation stopper 3) and is continuous with the convex portion 31A. The recessed part 32 and the convex part 31A have an inclined part 30 having an inclined cross-sectional shape, and this inclined part 30 serves as a part that connects the recessed part 32 and the convex part 31A. Further, the convex portion 31A has an upright portion 31Ab having a steeper cross-sectional shape than the inclined portion 30 on the side opposite to the screw shaft portion 2.

The recessed part 32 has an inclined part 30 that becomes deeper as it approaches the screw shaft part 2 from the most protruding end 31Aa, and has a height equivalent to that of the seat surface 11 from the inner end 30b of the inclined part 30 to the inner edge 32a. It has a straight portion 32A with a straight cross section that is formed parallel to each other. In other words, the recessed portion 32 has a linear portion 32A having a gentler slope than the sloped portion 30, with the inner end 30b of the sloped portion 30 serving as a slope change end. The linear portion 32A is continuous around the axis of the screw shaft portion 2 (hereinafter referred to as “circumferential direction”) so as to have different lengths. As a result, the cross-sectional shape along the radial direction of the detent part 3 (cut along a line segment perpendicular to the outer edge 31 of the detent part 3 and passing through the center of the screw shaft part 2) has a non-similar shape around the entire circumference. formed continuously. The convex portion 31A has an inclined portion 30 on the screw shaft portion 2 side and an upright portion 31Ab on the opposite side to the screw shaft portion 2, and connects the inclined portion 30 and the upright portion 31Ab. The most protruding end 31Aa is tapered toward the lower side X1 in the spiral direction. In this embodiment, the inner edge 32a of the recess 32 extends all the way to the annular groove 21, and the annular groove 21 and the recess 32 are continuous over the entire circumference (see also FIG. 1). Further, the outer edge 32b of the recessed part 32 extends all the way to the most protruding end 31Aa of the convex part 31A. ing. That is, the recessed part 32 is formed in an endless shape surrounding the screw shaft part 2.

FIG. 5 shows the center of the screw shaft portion 2 and the rounded corner portion 31a at a position where the convex portion 31A is farthest from the annular protrusion 22, that is, at a position equivalent to the outer peripheral edge 11a of the seat surface 11 shown in FIG. An enlarged cross-sectional view cut along a line passing through is shown. In FIG. 6, a line segment is cut that passes through the position where the convex portion 31A is closest to the annular protrusion 22, that is, the radially innermost portion of the connection side 31b shown in FIG. 3, and the center of the screw shaft portion 2. An enlarged cross-sectional view is shown.

As shown in FIGS. 5 and 6, the upright portion 31Ab of the convex portion 31A is formed perpendicular to the seat surface 11 of the head 1, and the inclined portion 30 is formed along a virtual perpendicular line parallel to the upright portion 31Ab. The inclination angle θ with respect to L is set to about 55 degrees. As shown in FIG. 5, the inclined part 30 located at the rounded corner part 31a has a connecting inclined part 30a that connects the inclined parts 30 adjacent to each other in the circumferential direction, and this connecting inclined part 30a has an inclined angle θ It is formed with a gentler slope. Due to the connection slope portions 30a, the slope portions 30 of the adjacent connection sides 31b each have a cross-sectional shape along the radial direction of the detent portion 3 that is discontinuous in the circumferential direction (see also FIG. 3). Incidentally, the inclination angle θ may be 45 degrees or more and 70 degrees or less, preferably 50 degrees or more and 60 degrees or less, and more preferably about 55 degrees. If the inclination angle θ is less than 45 degrees, the thickness of the convex portion 31A will become too small, resulting in a decrease in fluidity during molding and a decrease in rigidity. If the inclination angle θ exceeds 70 degrees, the convex If the portion 31A becomes too large, the volume of the recessed portion 32 becomes small, resulting in insufficient metal storage volume. Further, the height L1 of the convex portion 31A is set to about one third of the groove width L2 of the annular groove portion 21. The height L1 of the convex portion 31A is preferably one-fourth or more and one-half or less of the groove width L2 of the annular groove portion 21, and if it is less than one-fourth, the volume of the recessed portion 32 becomes small. As a result, the metal accommodation volume becomes insufficient, and if the volume exceeds one-half, it becomes difficult for the metal to flow smoothly into the recessed portion 32.

As shown in FIGS. 3 and 6, at the position where the convex portion 31A is closest to the annular protrusion 22, the inner end 30b of the inclined portion 30 in this embodiment is the most of the annular protrusion 22 in the spiral direction X. It is located slightly inward in the radial direction from the outer periphery. With this configuration, the clinching stud bolt B press-fitted into the metal plate T can secure a large area of the seating surface 11 facing the metal plate T (see also FIG. 8). As a result, it becomes possible to secure a large volume of the metal plate material T that enters between the pair of adjacent rounded corners 31a of the seat surface 11, and the idling torque can be improved. In addition, since the inner end 30b of the inclined portion 30 is located radially inward than the outermost circumference of the annular protrusion 22, the thick metal accommodated in the annular groove 21 and the recessed portion 32 resists the pull-out load. It becomes dominant and can increase the pull-out load.

Next, the effects when the clinching stud bolt B according to this embodiment is press-fitted into the metal plate T will be explained using FIGS. 7 and 8. The metal plate material T is a thin metal plate such as a steel plate, has a through hole Ta larger than the diameter of the annular protrusion 22 and smaller than the outer diameter of the rotation stopper 3 formed in advance, and is pressed by a hydraulic press P. It is supported by a jig G that can withstand the pressing force of .

As shown in FIG. 7, the clinching stud bolt B before being press-fitted into the metal plate T has the most protruding end 31Aa of the rotation stopper 3 in contact with the periphery of the through hole Ta, and the head 1 is pressed into the hydraulic press P. are in contact with each other. At this time, the annular protrusion 22 is housed inside the through hole Ta, and the male threaded portion 2A of the screw shaft portion 2 protrudes toward the jig G side.

Next, as shown in FIGS. 7 and 8, when the head 1 is pressed by the hydraulic press P, the convex part 31A of the detent part 3 bites into the metal plate T, and the clinching stud bolt B is pushed downward (screwing). The seat 11 is moved toward the lower side in the direction X1) and is press-fitted until the seat surface 11 comes into contact with the metal plate T. At this time, the metal of the crushed metal plate T corresponding to the volume of the convex portion 31A smoothly flows radially inward along the inclined portion 30 and is accommodated in the recessed portion 32 and the annular groove portion 21. As a result, the clinching stud bolt B when fixed to the metal plate T has an excellent overall appearance.

In the clinching stud bolt B according to the present embodiment, a rotation stopper 3, an annular groove 21, and an annular protrusion 22 protruding from the seat surface 11 of the head 1 are arranged in this order along the spiral direction X. A recessed portion 32 recessed toward the upper side X2 in the screwing direction is formed in the rotation prevention portion 3. As a result, when the detent portion 3 crushes the metal plate T, the metal of the metal plate T enters into the recessed portion 32 in addition to the annular groove 21, thereby preventing the metal from protruding to the outside of the annular protrusion 22 in the radial direction. be done. As a result, the generation of burrs is prevented, so when fixing another part to the metal plate T, there is no inconvenience such as the other part being damaged by the burr or the burr turning into foreign matter and scattering around, thereby improving quality. can be increased. In addition, the metal of the metal plate T enters into the annular groove 21 to ensure the pull-out load, and the metal of the metal plate T also enters the recess 32, increasing the shearing area of the metal plate T and reducing the idling torque. can be improved. Moreover, since the metal plate T preferentially enters the recessed part 32, the metal plate T is difficult to protrude outward in the radial direction of the recessed part 32, and warping of the metal plate T is prevented. There is no inconvenience such as interference with other parts, and quality can be improved.

Further, since the recessed portion 32 is formed deeper toward the screw shaft portion 2, the crushed and flowing metal of the metal plate T is smoothly guided in the direction of the annular groove portion 21. Since the recess 32 and the annular groove 21 are continuous over the entire circumference, the crushed and flowing metal of the metal plate T is guided in the direction of the annular groove 21 without any barrier. In other words, since the recessed portion 32 has an endless shape surrounding the screw shaft portion 2, the crushed and flowing metal of the metal plate T is guided in the direction of the annular groove portion 21 without any barrier, and the recessed portion 32 Sufficient capacity will be secured. As a result, the protrusion of the flowing metal is further suppressed and the generation of burrs is prevented, so quality can be improved.

Further, the recessed portion 32 includes an inclined portion 30 that becomes deeper as it approaches the screw shaft portion 2 from the most protruding end 31Aa, and a connection inclined portion 30a that connects circumferentially adjacent inclined portions 30 and has a gentler slope than the inclined portion 30. and a continuous linear portion 32A having a gentler slope than the connecting slope portion 30a and having different lengths in the circumferential direction. As a result, in the radial cross-sectional shape of the detent portion 3 in this embodiment, non-similar shapes are continuously formed around the entire circumference. As a result, the metal of the flowing metal plate material T enters the recessed part 32 in a discontinuous shape in the circumferential direction, and the convex part 31A and the metal that has entered the recessed part 32 come into contact with each other, resulting in resistance during idling. Therefore, the idling torque can be increased. Further, by providing the linear portion 32A in the recessed portion 32, it becomes possible to insert a large amount of metal into the inner edge 32a of the recessed portion 32 adjacent to the annular groove portion 21, and the idling torque can be further increased.

Furthermore, in the present embodiment, the recessed portion 32 is extended to the outer edge 31 of the rotation stopper 3 to form a convex portion 31A that projects in a tapered state on the outer edge 31 of the rotation stopper 3. Therefore, the convex portion 31A can bite into the metal plate T and improve the idling torque. Since the convex portion 31A is formed at the same height over the entire area, the convex portion 31A bites into the metal plate T uniformly, thereby further improving the idling torque. Moreover, since the convex portion 31A acts as a barrier, the metal of the metal plate T that has entered the recessed portion 32 is difficult to protrude outside the convex portion 31A in the radial direction, and warping of the metal plate T can be reliably prevented.

Further, since the convex portion 31A is inclined toward the screw shaft portion 2 side, and the upright portion 31Ab on the opposite side to the screw shaft portion 2 is erected at a steep slope, the metal plate T is placed in the recessed portion 32. As a result, the metal plate T can be reliably prevented from protruding outward in the radial direction of the recessed portion 32. Moreover, even when the metal plate T rotates and rotational torque is applied to the clinching stud bolt B, the upright portion 31Ab stands perpendicularly to the metal plate T, so the clinching stud bolt B The component force in the pull-out direction becomes extremely small, and the pull-out load can be appropriately secured.

[Other embodiments]
(1) The non-circular shape of the detent portion 3 may be a hexagonal shape in which the connection side 31b is formed in a straight line, or may be a polygonal shape such as a triangular, square, or pentagonal shape.
(2) The recessed portion 32 of the detent portion 3 may have any shape, such as being partially provided along the circumferential direction, and is not particularly limited. In this case, it is preferable that the cross-sectional shape of the detent portion 3 along the radial direction is formed in a non-similar shape in at least a portion of the circumferential direction. As long as the shape can be constructed in a non-similar shape, the inclined part 30 of the recessed part 32 may be omitted and it may be constructed only of continuous linear parts 32A with different lengths in the circumferential direction, or the diameter A plurality of depressions having different directional positions may be provided along the circumferential direction. Further, it is preferable that at least the inner edge 32a of the recess 32 is continuous in the circumferential direction so that the metal that has entered the recess 32 can flow to the annular groove 21.
(3) The annular groove portion 21 and the annular protrusion 22 may not be formed in an annular shape, but may be formed in an annular shape with a polygonal outer shape. Further, the through hole Ta of the metal plate T may be formed smaller than the diameter of the annular protrusion 22 so that the inner circumferential portion of the through hole Ta is also crushed by the annular protrusion 22 .
(4) The most protruding end 31Aa of the convex portion 31A may be sharpened. In this case, the most protruding end 31Aa of the most protruding end 31Aa easily bites into the metal plate material T.
(5) In addition to the metal plate T, the plate material to be attached is not particularly limited as long as it is made of a fluid (ductile) material.
(6) The threaded shaft portion 2 may have a female threaded portion instead of the male threaded portion 2A.

INDUSTRIAL APPLICATION This invention can be utilized for the clinching stud bolt fixed to the board|plate material to which it is attached in a state which prevents it from coming out and a state which prevents rotation.

1 : Head 2 : Screw shaft part 3 : Stopper part 11 : Seat surface 21 : Annular groove part 22 : Annular protrusion 30 : Inclined part 31 : Outer edge 31a : Round corner part 31b : Connection side 31c : Valley part 31A : Convex part 31Ab : Standing part 32 : Recessed part B : Clinching stud bolt T : Metal plate material (plate material to be mounted)
X: Spiral direction X1: Lower side of the spiral direction X2: Upper side of the spiral direction

Claims (1)

head and
a screw shaft extending from the seat surface of the head;
a rotation stopper formed in a non-perfect circular shape surrounding the screw shaft when viewed in the spiraling direction of the screw shaft, and bulging from the seat surface toward the lower side in the spiraling direction;
an annular groove recessed in an annular shape toward the inside in the radial direction of the screw shaft at a position adjacent to the rotation stopper on the downward side of the screw shaft in the screw shaft;
an annular protrusion annularly protruding toward the outside in the radial direction of the screw shaft at a position adjacent to the annular groove on the downward side in the spiral direction of the screw shaft;
The mounting target plate material is sandwiched between the seat surface and the annular protrusion,
The clinching stud bolt is fixed to the plate material to be attached in a non-slip and non-rotating state by forming a recessed part in the anti-rotation part toward the upper side in the spiraling direction. ,
The outer edge of the rotation stopper includes a plurality of radially arranged rounded corners serving as apexes, a plurality of connection sides formed concavely inward in the radial direction connecting the pair of rounded corners, and a connection side. It has a trough which is the most radially inner part of the
The clinching stud bolt is characterized in that the height of the valley portion is set lower than the round corner portion, and the connection side is configured to connect the valley portion and the round corner portion.

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