JP2003290864A - Self-piercing rivet fastening device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-piercing rivet fastening device obtaining sufficient fastening strength regardless of the combination of the material and thickness of a metallic sheet. <P>SOLUTION: The device is equipped with a punch and a die 3 opposing each other. The die 3 is composed of die parts 3a, 3b having a dish-like supporting face 3c for holding a material to be fastened, a base 2 which supports the die parts 3a, 3b freely movably forwards and backwards in the punching direction, a center pin 4 which is fixed on this base 2 and inserted into a through-hole 3d penetrating through the center axis of the die parts 3a, 3b, and springs 6 which press the die parts 3a, 3b in the punching direction by prescribed repulsive force. When pressurizing force on the supporting face 3c becomes larger than the repulsive force of the springs 6 at fastening a rivet, the die 3 shifts in the counter punching direction, with the center pin 4 projecting from the through-hole 3d, making the self-piercing rivet expanding in the radial direction. The self-piercing rivet fastening device is characterized in that the prescribed repulsive force can be continuously varied. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-piercing rivet fastening device for fastening stacked plate-shaped materials to be fastened with a self-piercing rivet without completely penetrating them.

[0002]

2. Description of the Related Art In the field of automobile manufacturing and the like, self-piercing rivets are sometimes used to fasten sheet metal sheets to each other. A self-piercing rivet means that when the metal sheets are fastened together, the legs of the rivet bite into the metal sheet at the bottom and develop into a morning glory, so that the rivets do not penetrate the metal sheet at the bottom and the metal sheets are connected to each other. A rivet to be fastened.

The shape of this self-piercing rivet is shown in FIG.
It was shown to. The self-piercing rivet 100 has a circularly expanded head 101 and a leg 102 extending from the head 101. In this example, the leg portion 102 is a hollow cylinder, but the leg portion 102 does not have to be a hollow cylinder as long as the end portion has a recess having a predetermined shape. Hereinafter, the "self-piercing rivet" will be simply referred to as "rivet".

FIG. 4B shows how the metal sheet is fastened by the rivet 100. A dedicated rivet fastening device 200 is used to fasten the metal thin plate with the rivets 100. The rivet fastening device 200 includes a punch 201,
It includes a die 202, an arm 203, a main body 204 and the like.
A punch 201 for pressing the head 101 of the rivet 100 is provided at the end of the main body 204. Body 20
A U-shaped arm 203 extends from the side surface of 4,
A die 202 is provided at the end of the arm 203 so as to face the punch 201.

The punch 201 can be moved in the direction of the die 202 while holding the rivet 100 by a hydraulic mechanism (not shown) or the like. After the metal thin plates 205a and 205b are positioned, the punch 201 is placed between the punch 201 and the die 202. Insert and
The metal thin plates 205a and 205b are sandwiched by the punch 201 holding the rivet 100 and the die 202. Then, the leg portion 102 of the rivet 100 penetrates the metal thin plate 205a, and when it reaches the metal thin plate 205b, the metal thin plate 205b is bitten and crimped to develop into a morning glory, and the metal thin plate 205b is not penetrated. 205a, 2
05b are fastened together.

A thin metal plate 205a formed by the rivet 100,
The fastening of 205b will be described in detail with reference to the process chart of FIG. In FIG. 5A, the rivet 100 has a thin metal plate 205.
It is the schematic diagram which drew just before penetrating into a and 205b. The rivet 100 is pressed by the punch 201,
FIG. 6 is a schematic diagram depicting a stage (starting stage) just about to penetrate into the thin metal plate 205a. A rivet 100, a metal thin plate 205a, and a metal thin plate 205b are arranged in order from the punch 201 side between the punch 201 and the die 202, and the head 101 of the rivet 100 is the punch 2
Pressed by 01. Also, the thin metal plate 205b
Are supported by the die 202.

The front end of the die 202 is circular in a front view, and the outer peripheral portion and the central portion are bulged, and an annular bottom face is formed between the outer peripheral portion and the central portion. Hereinafter, the protrusion in the center of the die 202 will be referred to as a central protrusion 202a, and the protrusion in the outer peripheral portion will be referred to as an outer peripheral protrusion 202b. The die 202 is a metal thin plate 205 protruding in the direction of the die 202 as the rivet 100 penetrates the metal thin plates 205a and 205b.
In addition to supporting a and 205b, the central projection 202a has a function of deploying the leg portion 102 of the rivet 100 in a morning glory shape as described later.

FIG. 5B is a schematic view showing a stage (piercing stage) in which the rivet 100 is penetrating the thin metal plates 205a and 205b. The rivet 100 whose head 102 is pressed by the punch 201 is a metal thin plate 20.
Penetrate into 5a. Accordingly, the thin metal plate 205
The a and 205b are pressed against the surface of the die 202 and are plastically deformed along the shape of the die 202.

In FIG. 5 (c), the rivet 100 is further pressed, and the leg portion 102 of the rivet 100 has a central protrusion 202.
It is a schematic diagram which shows the stage (flare stage) which began to develop by interfering with a. At this stage, the tip of the leg portion 102 of the rivet 100 has the thin metal plates 205a, 20a.
By interfering with the central protrusion 202a of the die 202 via 5b, the leg portion 102 starts to expand in the left-right direction in the drawing along the radius of the central protrusion 202a.

In FIG. 5D, the rivet 100 is further pressed, and the head 101 of the rivet 100 and the thin metal plate 205.
The surface of a is flush with the metal thin plates 205a and 205b.
It is a schematic diagram which shows the stage (completion stage) which the conclusion of was completed. At this stage, the head 101 of the rivet 100
Is completely pushed into the metal thin plate 205a, and the metal thin plate 2 is inserted between the head 101 and the leg 102 developed in the left-right direction in the drawing.
By sandwiching 05a and 205b, both metal thin plates 2
05a and 205b are fastened. In addition, rivet 1
The tip end of the leg portion 102 of 00 is pierced through the metal thin plate 205a and bites into the metal thin plate 205b to caulk and fasten both metal thin plates 205a and 205b. Thus, the rivet 100 can fasten the metal thin plates 205a and 205b without penetrating the lower metal thin plate 205b.

Next, with reference to FIG. 6, the relationship between the load applied to the rivet 100 by the punch 201 and the pushing stroke of the rivet 100 in each of the above-mentioned stages (starting stage to final stage) will be described. In this figure, the vertical axis represents the load applied to the rivet 100, and the horizontal axis represents the pushing stroke, which is the amount of displacement of the head 101 of the rivet 100. At the start stage, the load is applied to the rivet 100 by the punch 201, but the rivet 100 has not yet penetrated into the thin metal plate 205a, so that the pushing stroke amount of the rivet 100 becomes zero.

When the load applied from the punch 201 to the rivet 100 exceeds a certain value, the rivet 100 bites into the metal thin plates 205a and 205b. In the initial stage of fastening, the rivet 100 smoothly moves to the metal thin plate 205a. , 205b. That is, since the increase amount of the pushing stroke is large with respect to the increase amount of the load applied to the rivet 100, the inclination of the graph becomes small (pierce stage).

Subsequently, the rivet 100 is attached to the metal thin plate 20.
5a, 205b through the central protrusion 202a of the die 202
Upon contact with the rivet 100, the legs 102 of the rivet 100 start to develop like a morning glory (flare stage). At this stage, the inclination of the graph becomes larger than that at the piercing stage. This is because a large load is required in order to make it spread like a morning glory while making it bite into 205b.

Further, when a load is applied to the rivet 100, the expanded leg portion 102 will move to the thin metal plates 205a, 205.
It will bite deeper into b and eventually rivet 100
The head 101 (the lower surface of the flange of the head 101) is flush with the metal thin plate 205a, and the fastening of the metal thin plates 205a and 205b by the rivet 100 is completed (final stage).

[0015]

In fastening the metal thin plates 205a, 205b using the self-piercing rivet 100, in order to obtain a sufficient fastening force without penetrating the lower metal thin plate 205b, the metal thin plates 205a, 205b, 205b
It was necessary to change the height and shape of the central protrusion 202a of the die 202 depending on the material, plate thickness, and the like. That is, a plurality of dies 202 whose shapes are slightly changed are prepared,
There is a problem that the fastening conditions must be determined while exchanging these dies 202.

Further, there is a particular problem in the case where the lower metal thin plate 205b is thinner than the upper metal thin plate 205a, and if the die 202 to be used is poorly selected, the lower metal thin plate 205b.
Since the rivet 100 is thin, the rivet 100 does not sufficiently dig into the metal thin plate 205b at the above-mentioned final stage (FIG. 5 (d)) and the fastening force is insufficient, or conversely, the rivet 100 penetrates the metal thin plate 205b. Occasionally, a defect such as an accident occurred.

The present invention has been made in view of the above problems, and provides a self-piercing rivet fastening device capable of obtaining a sufficient fastening strength regardless of the combination of the material and the thickness of the thin metal plate. This is an issue.

[0018]

[Means for Solving the Problems] The present invention has the following structure in order to solve the above problems. The invention according to claim 1 has a punch and a die which are opposed to each other, and by pressing down a self-piercing rivet supported by the punch, the plate-like fastened material laminated on the die is completely removed. A self-piercing rivet fastening device that fastens without penetrating, wherein the die supports a die part having a dish-shaped support surface for supporting the material to be fastened, and supports the die part so as to be movable back and forth in the punch direction. The rivet includes a base portion, a center pin fixed to the base portion and inserted into a through hole penetrating the central axis of the die portion, and an elastic member for biasing the die portion in a punch direction with a predetermined elastic force. When the pressing force applied to the supporting surface at the time of fastening becomes larger than the elastic force of the elastic member, the die moves in the anti-punch direction, the central pin projects from the through hole, and the self-piercing rivet is radially attached. Expanded to That together constitute a self-piercing rivet fastening device is a self-piercing rivet fastening device is characterized in that continuously changeable configured the predetermined elastic force.

According to the first aspect of the present invention, the elastic member biases the die portion in the punch direction with a predetermined elastic force,
This resilience can be changed continuously. When the pressing force applied to the supporting surface through the material to be fastened exceeds this elastic force, the die part moves in the anti-punch direction, the central pin projects from the through hole, and the leg part of the rivet rises. Expand the diameter. In the self-piercing rivet fastening device of the present invention, since the elastic force of the elastic member can be changed, it is possible to continuously change the timing (pressing force) at which the central pin projects. This makes it possible to always deploy the leg portion of the rivet at the optimum timing (pressing force) regardless of the material and plate thickness of the material to be fastened.

According to a second aspect of the present invention, the elastic member is a spring interposed between the die portion and the base portion, and the adjusting plate for continuously changing the degree of expansion and contraction of the spring. Is provided in the vicinity of the anti-punch end of the die part, and the adjusting plate changes the length of the spring to continuously change the elastic force, thereby self-piercing rivet fastening. It is a device.

According to the second aspect of the invention, as the elastic member, a spring provided between the base portion and the die portion is used. Also, since the degree of expansion and contraction of this spring can be continuously changed by the adjust plate, it becomes possible to continuously change the elastic force of the spring, and the timing (pressing force) at which the center pin projects is continuous. Can change. As a result, regardless of the material and plate thickness of the material to be fastened, the leg of the rivet is always at the optimum timing (pressing force).
Can be deployed with.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings as appropriate. 1 (a) is a sectional view of a die in the self-piercing rivet fastening device of the present invention, and FIG. 1 (b) is a sectional view taken along line XX of FIG. 1 (a). Figure 1
The die 1 shown in (a) is used, for example, in place of the die 202 of the self-piercing rivet fastening device 200 shown in FIG. 4 (b). The die 1 includes a base portion 2, a die portion 3,
It is composed of a central pin 4, an adjusting plate 5, a disc spring 6, a stopper 7, and the like.

The die part 3 is a member in which two cylinders having different diameters (a large diameter cylinder 3a and a small diameter cylinder 3b) are coaxially connected, and a through hole 3d penetrates along the central axis of the die part 3. ing. The large-diameter cylinder 3a is arranged on the punch side, and the punch-side end surface of the large-diameter cylinder 3a is formed in a dish shape and supports the material to be fastened to the die 1 side when the rivet is fastened. It is the surface 3c. Further, a disc spring 6 is interposed between the large diameter cylinder 3a and the base portion 2, and the large diameter cylinder 3a is constantly urged in the punch direction by the elastic force of the disc spring 6.

Small-diameter cylinder 3 having a smaller diameter than large-diameter cylinder 3a
b is inserted in a cylindrical opening 2a provided in the base portion 2 and is slidable in the punching direction inside the cylindrical opening 2a. The small diameter cylinder 3b is formed longer than the cylindrical opening 2a, so that the small diameter cylinder 3b has a portion protruding from the cylindrical opening 2a. An annular adjusting plate 5 is screwed into the projecting portion, and the adjusting plate 5 changes the distance (clearance) between the large-diameter cylinder 3a and the base 2 to allow the disc spring 6 to move.
The resilience of can be adjusted. As shown in FIG. 1 (b), the adjusting plate 5 is provided with a projection 5a and the base 2 is provided with a groove 2b, so that even when the die unit 3 is rotated, the adjusting plate 5 rotates together. It is supposed not to. Accordingly, by rotating the large-diameter cylinder 3a with a finger or a tool, the distance between the large-diameter cylinder 3a and the base 2, and thus the elastic force of the disc spring 6 can be continuously and delicately adjusted.

A central pin 4 fitted into the through hole 3d is screwed into the base portion 2. By rotating this central pin 4 and moving it up and down, the supporting surface 3c of the central pin 4
The amount of protrusion from can be changed. In order to fix the central pin 4 at a predetermined position, a threaded hole is formed from the side surface of the base 2 to the threaded portion of the central pin 4, and a central pin stopper 8 is screwed into the threaded hole. .

A stopper 7 is provided on the side surface of the large-diameter cylinder 3a so that the die 3 does not rotate carelessly when the rivet is fastened and the distance between the large-diameter cylinder 3a and the base 2 does not change. There is.

When the rivet is fastened, a punch (not shown) presses the plate-shaped fastened material against the support surface 3c via the rivet. At this time, since the large diameter cylinder 3a is biased in the punch direction by the disc spring 6, the small diameter cylinder 3b has a cylindrical shape while the pressing force applied to the support surface 3c is smaller than the elastic force of the disc spring 6. It does not slide inside the opening 2a. However, when the rivet fastening progresses and the pressing force applied to the support surface 3c becomes larger than the elastic force of the disc spring 6, the small diameter cylinder 3b slides in the anti-punch direction inside the cylindrical opening 2a, and as a result, The center pin 4 fixed to the base portion 2 projects from the through hole 3d of the die portion 3. The rivet interferes with the protruding center pin 4 through the fastening material, whereby the leg portion develops like a bosh and bites into the fastening material to fasten the fastening material.

As described above, the elastic force of the disc spring 6 is the height of the adjusting plate 5, more specifically, the distance between the adjusting plate 5 and the large diameter cylinder 3a, that is, the large diameter cylinder 3a and the base 2 ( It can be changed by changing the clearance (clearance) from the upper surface. For example, die unit 3
If the gap between the large-diameter cylinder 3a and the base 2 is narrowed by screwing in, the disc spring 6 contracts, so that the elastic force of the disc spring 6 increases, and therefore the die portion 3 slides in the cylindrical opening 2. The pressing force required to move it increases. That is, the pressing force required to increase the amount of protrusion of the center pin 4 from the support surface 3c increases.

On the contrary, the die part 3 is pulled out and the large diameter cylinder 3
If the distance between a and the base portion 2 is widened, the disc spring 6 expands, so that the elastic force of the disc spring 6 becomes small, and accordingly, the die portion 3
The pressing force required to slide the in the cylindrical opening 2 is small. That is, the pressing force required to increase the amount of protrusion of the center pin 4 from the support surface 3c is reduced.

By the way, the projecting timing of the center pin 4 is closely related to the timing of deploying the rivet in the material to be fastened in a bosh-like manner. In the self-piercing rivet fastening device of the present invention, the timing of projecting the central pin 4 can be continuously changed by changing the screwing amount of the die portion 3, so that conventionally, the material of the fastened material and the plate It is no longer necessary to perform die replacement work that was done according to the thickness,
It is possible to always fasten the material to be fastened with sufficient strength.

In this embodiment, the disc spring 6 is used to urge the die portion 3 toward the punch side. However, instead of the disc spring 6, an elastic body such as urethane rubber is used. May be used. Also, instead of the disc spring 6,
The die unit 3 may be biased to the punch side by a hydraulic mechanism, an electromagnetic mechanism, or the like.

Next, the fastening of the fastened material using the self-piercing rivet fastening device of the present invention will be described with reference to the process chart of FIG. FIG. 2A shows that the self-piercing rivet 20 pressed by the punch 30 with a predetermined load has the metal thin plates 35a, 3a.
It is a schematic diagram which drew the start stage just before it bites into 5b.
The metal thin plate 3 under the laminated metal thin plates 35a and 35b
5b is supported by the supporting surface 3c of the die unit 3. At this stage, since the pressing force applied to the support surface 3c is smaller than the elastic force of the disc spring 6 (not shown), the large diameter cylinder 3a is not displaced in the anti-punch direction, and therefore the through hole of the die portion 3 is not formed. The center pin 4 fitted in 3d does not project.

FIG. 2B is a schematic diagram illustrating a piercing step in which the punch 30 is further loaded, and as a result, the self-piercing rivet 20 penetrates the thin metal plates 35a and 35b. When the punch 30 further presses the self-piercing rivet 20, the leg portion 2 of the self-piercing rivet 20 is pressed.
0b is the metal thin plate 35a while pressing the metal thin plate 35a.
Penetrate deep inside. As a result, the metal thin plates 35a, 3
5b is plastically deformed and is in contact with the bottom of the support surface 3c. At this piercing stage, the pressing force applied to the support surface 3c is smaller than the elastic force of the disc spring 6 (not shown), and as described above, the center pin 4 does not protrude from the through hole 3d. Therefore, the leg portion 20b of the self-piercing rivet 20 has the center pin 4
And the leg portion 20b of the self-piercing rivet 20 does not expand.

FIG. 2 (c) shows that the punch 30 is further loaded, which results in the legs 20 of the self-piercing rivet 20.
FIG. 6B is a schematic diagram illustrating a flare stage that develops in the horizontal direction of the drawing. At this stage, since the pressing force applied to the support surface 3c exceeds the elastic force of the disc spring 6, the die portion 3 is displaced in the anti-punch direction against the elastic force of the disc spring 6. As a result, the center pin 4 projects from the through hole 3d, and the center pin 4 interferes with the leg portion 20b of the self-piercing rivet 20 via the thin metal plates 35a and 35b, and the leg portion 20b has a tip shape of the center pin 4. Along the direction of the drawing, it begins to develop like a morning glory. As the leg portion 20b expands in this manner, the leg portion 20b bites into the thin metal plates 35a and 35b,
Great fastening power is created.

In FIG. 2 (d), the punch 30 is further loaded and, as a result, the head 20 of the self-piercing rivet 20 is loaded.
It is a schematic diagram which drew the final step which a and a metal thin plate 35a become flush, and fastening is completed. At this stage, since the pressing force applied to the supporting surface 3c exceeds the elastic force of the disc spring 6, the center pin 4 is in a state of protruding from the through hole 3d. Therefore, the pressing force applied from the punch 30 to the self-piercing rivet 20 is mainly
The self-drilling rivet 20 is consumed by unfolding the leg portions 20b, and further digs into the thin metal plates 35a and 35b to fasten them with a strong fastening force.

Next, the relationship between the load (pressing force) applied from the punch 30 to the rivet 20 and the pushing stroke of the self-piercing rivet 20 will be described with reference to FIG.
The pushing stroke indicates the amount of displacement of the head portion 20a of the self-piercing rivet 20.

In the starting stage (FIG. 2 (a)), the punch 30 applies a load to the self-piercing rivet 20, but the self-piercing rivet 20 still has the metal sheets 35a, 3a.
Since it does not penetrate into 5b, the pushing stroke becomes 0.

In the piercing step (FIG. 2 (b)), the self-piercing rivet 20 smoothly penetrates into the thin metal plates 35a, 35b according to the load applied from the punch 30 without interfering with the supporting surface 3c or the like. Therefore, the slope of the graph becomes smaller. That is, the increase amount of the pushing stroke of the self-piercing rivet 20 is larger than the increase amount of the load applied to the self-piercing rivet 20 by the punch 30.

Then, when the load applied to the self-piercing rivet 20 is increased, the load applied to the self-piercing rivet 20 from the punch 30 eventually exceeds the elastic force of the disc spring 6 and the die portion 3 is counter-punched. By moving in the direction, the center pin 4 starts to project from the through hole 3d. As a result, the leg portion 20b of the self-piercing rivet 20 starts to develop like a bosh along the shape of the central pin 4 by interfering with the central pin 4 via the thin metal plates 35a and 35b (flare stage (Fig. 2 ( c))).

One of the features of the present invention is that, as described above, the elastic force of the disc spring 6 is preset because the interval between the large-diameter cylinder 3a of the die part 3 and the base part 2 is increased or decreased. Adjust,
The point is that the projection timing of the center pin 4 can be continuously changed. In FIG. 3, three graphs A, B, and C in which the elastic force of the disc spring 6 is changed are drawn. Graph A is a graph when the disc spring 6 is contracted to increase the elastic force of the disc spring 6. In this case, the load required to cause the center pin 4 to project (start the projecting) becomes large. Graph C is a graph in the case where the disc spring 6 is expanded and the elastic force of the disc spring 6 is reduced. In this case, the load required to cause the center pin 4 to project (start the projecting) becomes small.

As described above, according to the present invention, the load for starting the protrusion of the center pin 4 can be continuously changed by screwing the die portion 3 by the adjusting plate 5, so that the die itself is not replaced. A thin metal plate 35a,
It is possible to adjust the optimal projection timing of the center pin 4 according to the material and plate thickness of 35b, and it is possible to always perform fastening with sufficient strength. The clearance (clearance) between the large-diameter cylinder 3a and the base 2 is adjusted with a finger or a tool.
By rotating a and screwing it in or out, it can be performed continuously and delicately. In this embodiment, the adjustment plate 5 is made non-rotatable, and the interval is adjusted by screwing the die part 3 into place. However, the die part 3 (large diameter cylinder 3a) is made non-rotatable, while the adjustment plate 5 is made non-rotatable. May be made rotatable, and the above-mentioned interval may be adjusted by the rotation amount of the adjusting plate 5. In this case, if the adjust plate 5 is made rotatable from the outside, it is easy and convenient to adjust the interval (the interval between the large diameter cylinder 3a and the upper surface of the base 2). That is, it is convenient to continuously adjust the elastic force of the disc spring 6.

At the final stage (FIG. 2 (d)), the load applied to the self-piercing rivet 20 is further increased. This load is mainly used for expanding the leg portion 20b of the self-piercing rivet 20 and biting it into the metal thin plates 35a, 35b. Then, the head portion 20a of the self-piercing rivet 20.
Becomes flush with the metal thin plate 35a, and the fastening process is completed.

[0043]

The present invention has the following remarkable effects. Since the self-piercing rivet fastening device of the present invention can continuously change the elastic force of the elastic member, the protrusion timing of the center pin for deploying the leg portion of the self-piercing rivet is set to an arbitrary pressing force. It becomes possible to do. As a result, the center pin can always be projected at the optimum timing (pressing force) regardless of the plate thickness or material of the material to be fastened, and the fastening with sufficient strength can be performed, and the center pin can be performed. It is possible to easily set the timing for projecting the slab (claim 1).

In the self-piercing rivet fastening device of the present invention, the spring is used as the elastic member, and the adjusting plate capable of continuously adjusting the degree of expansion and contraction of the spring is provided. Therefore, the fastening having a sufficient strength is always performed. In addition to the above, the timing for projecting the central pin can be easily set (claim 2).

[Brief description of drawings]

FIG. 1 is a sectional view (a) of a die in a self-piercing rivet fastening device of the present invention and a sectional view (b) taken along line XX of FIG. 1 (a).
Is.

FIG. 2 is a process drawing of fastening a material to be fastened using the self-piercing rivet fastening device of the present invention.

FIG. 3 is a graph showing the relationship between the load (pressing force) applied to the rivet from the punch and the pushing stroke of the self-piercing rivet in the self-piercing rivet fastening device of the present invention.

FIG. 4 is a perspective view (a) of the self-piercing rivet and a side view (b) of the self-piercing rivet fastening device.

FIG. 5 is a process diagram of fastening a thin metal plate with a conventional self-piercing rivet.

FIG. 6 is a graph showing a relationship between a load applied to a self-piercing rivet by a conventional punch and a pushing stroke of the self-piercing rivet.

[Explanation of symbols]

1 die 2 base 3 die section 3a Large diameter cylinder 3b small diameter cylinder 3c Support surface 3d through hole 4 center pin 5 Adjust plate 6 Disc spring 7 stopper 20 self-piercing rivets 20a head 20b leg 30 punches 35a, 35b thin metal plate

Claims (2)

[Claims] 1. A punch and a die which are opposed to each other, and by pressing a self-piercing rivet supported by the punch, the plate-like fastened material laminated on the die is not completely penetrated. A self-piercing rivet fastening device for fastening, wherein the die includes a die part having a dish-shaped support surface for supporting the material to be fastened, and a base part for supporting the die part so as to be movable back and forth in the punch direction. A center pin fixed to the base part and inserted into a through hole penetrating the center axis of the die part, and an elastic member for urging the die part with a predetermined elastic force in the punch direction. When the pressing force applied to the surface becomes larger than the elastic force of the elastic member, the die moves in the counter-punch direction, the central pin projects from the through hole, and the self-piercing rivet is radially expanded. Self-piercing Together constituting a rivet fastening device, the self-piercing rivet fastening device is characterized in that continuously changeable configured the predetermined elastic force. 2. The elastic member is a spring interposed between the die portion and the base portion, and an adjusting plate for continuously changing the degree of expansion and contraction of the spring is provided on an opposite side of the die portion. A self-piercing rivet fastening device which is provided in the vicinity of an end of a punch and which changes the length of the spring to continuously change the elastic force by the adjusting plate.