CN110788271A - Punch head - Google Patents

Abstract

The invention provides a punch for punching a rivet. The rivet is provided at least one end with a punched hole surrounded by a circumferential wall. The punch includes a body having an end face and a tapered portion. The end surface surrounds and is connected to the larger diameter bottom end of the conical portion. The diameter of the bottom end of the tapered portion is larger than the initial inner diameter of the punch hole of the rivet. As the tapered portion is pressed into the punched hole of the rivet, the peripheral wall can expand radially outward and eventually press against the end face of the body. The punch according to the present invention can 1) increase the pressing force between the riveted parts, avoiding looseness between the parts; 2) the rivet head is restrained or prevented from cracking after being stamped; and 3) make the size and shape of the rivet head obtained after stamping uniform, and increase the service life and strength of the rivet head.

Description

Punch head

Technical Field

The present invention relates to a punch, and more particularly to a punch for punching a rivet having a punched hole to effect riveting.

Background

Fig. 1A, 1B and 1C are a perspective view, a longitudinal sectional view and a top view, respectively, of a rivet. The body 1 of this rivet is generally cylindrical. Both ends of the main body 1 are opened with punched holes 10. Exemplary dimensions of such a rivet are as follows, as shown in FIG. 1B: the outer diameter a of the main body is 4mm, the punching diameter b is 2mm, the punching depth c is 4.5mm, and the rivet length L is 14.5 mm.

When the punched hole 10 of such a rivet is punched by a punch, the peripheral wall 11 of the punched hole 10 is deformed to extend outward in the radial direction of the body 1, and particularly the peripheral wall 11 at the end of the body 1 is deformed outward by being punched by the punch and forms a flange (i.e., a burring) which is pressed against an end edge of a rivet hole (the rivet hole is not shown in the drawings) of a member to be riveted, thereby pressing the rivet in the rivet hole, thereby achieving riveting between the members. Accordingly, such rivets are often used in applications where two or more components need to be riveted together.

Fig. 2A and 2B are a perspective view and a longitudinal sectional view, respectively, of a prior art punch. The punch 2 shown in fig. 2A and 2B has a cylindrical body 21 and a conical top 22. In carrying out the operation of stacking and riveting a plurality of sheet parts together, the sheet parts are first stacked and a rivet is placed in their concentrically arranged rivet holes, and then the top 22 of the punch 2 is pressed into the punched hole 10 of the rivet, so that the peripheral wall 11 of the punched hole 10 is deformed by spreading outward as described above, and finally the sheet parts are riveted together.

However, the inventors have found that the result of using such a punch 2 and riveting in the manner described above is at least one of the following disadvantages:

1) the pressing force between the riveted sheet parts is insufficient, in other words, the riveted sheet parts are easy to loosen;

2) the rivet head (e.g. the perimeter wall 11 of the end of the rivet described above) is susceptible to cracking after being stamped;

3) although the specifications of the rivets used are the same, after completion of the riveting operation using the above punch and riveting method, the resulting different rivet heads are not uniform in size and shape, thus adversely affecting subsequent processing; and is

4) The life and strength of the rivet head are reduced.

Disclosure of Invention

The inventors have made the present invention with the aim of overcoming at least one of the above drawbacks.

The invention provides a punch for punching a rivet. The rivet is provided at least one end with a punched hole surrounded by a circumferential wall. The punch includes a body having an end face and a tapered portion. The end surface surrounds and is connected to the larger diameter bottom end of the conical portion. The diameter of the bottom end of the tapered portion is larger than the initial inner diameter of the punch hole of the rivet. The peripheral wall extends radially outwardly and bears against the end face of the body as the tapered portion is pressed into the punch hole of the rivet.

Additionally, the diameter of the bottom end of the conical portion may be slightly less than or equal to or slightly greater than the initial outer diameter of the peripheral wall of the rivet.

And a groove is formed at the joint of the bottom end of the conical part and the end face of the main body.

The initial outer diameter of the peripheral wall of the rivet, viewed in the direction of the axis of the conical portion, may be slightly larger than the outer diameter of the groove, or may be intermediate between the outer and inner diameters of the groove.

The groove is recessed relative to both the side surface of the tapered portion and the end surface of the body.

The groove may have a circular arc-shaped cross-sectional profile. The radius of the circular arc is 5% to 10% of the wall thickness of the circumferential wall of the rivet.

The cone apex angle of the tapered portion is 90 ° to 150 °, and more specifically, the cone apex angle of the tapered portion is 120 °.

The cone is a truncated cone having a top surface with a diameter less than the initial inner diameter of the rivet punch and a height less than the depth of the rivet punch.

Drawings

In order to facilitate understanding of the invention, the invention is described in more detail below on the basis of exemplary embodiments and with reference to the attached drawings. The same or similar reference numbers are used in the drawings to refer to the same or similar parts. It should be understood that the drawings are merely schematic and that the dimensions and proportions of elements in the drawings are not necessarily precise.

Fig. 1A, 1B and 1C are a perspective view, a longitudinal sectional view and a top view, respectively, of a rivet.

Fig. 2A and 2B are a perspective view and a longitudinal sectional view, respectively, of a prior art punch.

Fig. 3A and 3B are a perspective view and a longitudinal sectional view, respectively, of a punch according to an embodiment of the present invention.

Fig. 3C is an enlarged view of the area 3C in fig. 3B.

Fig. 3D is a further enlarged view of the area 3D in fig. 3C.

Fig. 4A is a longitudinal sectional view of a state when a rivet is punched using a punch according to the present invention.

Fig. 4B is an enlarged view of the region 4B in fig. 4A.

Fig. 4C is a further enlarged view of region 4C in fig. 4B.

Detailed Description

Details of the rivet and punch in the prior art have been described in the foregoing "background" section with reference to fig. 1A to 2B, and thus will not be described in detail hereinafter. A punch according to an embodiment of the present invention will be described next with reference to fig. 3A to 4C.

Fig. 3A and 3B are a perspective view and a longitudinal sectional view, respectively, of a punch according to an embodiment of the present invention.

As shown in fig. 3A and 3B, the punch 3 mainly includes a main body 31, a tapered portion 32, and a circular (annular) end surface 33. The tapered portion 32 may be generally conical. The end face 33 is located at one end of the body 31. In this example, the body 31 is cylindrical. However, it will be appreciated by those skilled in the art that the body 31 may take any other shape as long as the body 31 has an end face 33. The tapered portion 32 is located at the center of the end face 33 and protrudes from the end face 33 in the axial direction of the main body 31 in a tapered manner.

Fig. 4A is a longitudinal sectional view of a state when the punch 3 is used to punch a rivet. Fig. 4B is an enlarged view of the region 4B in fig. 4A. Fig. 4C is a further enlarged view of region 4C in fig. 4B.

The diameter of the bottom end of the tapered portion 32 is larger than the initial inner diameter (i.e., the inner diameter before non-deformation) b of the punched hole 10 of the rivet, so that as the tapered portion 32 is pressed into the punched hole 10, the peripheral wall 11 of the punched hole 10 expands radially outward and eventually presses against the end face 33 of the punch 3, as shown in fig. 4A to 4C. In this way, in the process of applying pressure to the punched hole 10 using the punch 3, the peripheral wall 11 of the punched hole 10 is subjected to the pressure applied by the end face 33 of the punch 3 at the end of the punching process in addition to the pressure of the side face of the tapered portion 32 as in the related art.

Specifically, as shown in fig. 4B and 4C, the flange 12 (i.e., burring) formed by the peripheral wall 11 of the punched hole 10 of the rivet expanding outward as a result of being punched by the punch 3 is also acted on by the pressure applied by the end face 33 of the punch 3 at the end of the punching process. As a result, the flange 12 is firmly pressed against the end edge of a rivet hole (the rivet hole is not shown in the drawings) of the riveted part. Therefore, by performing the punching process on the rivet using the punch 3 disclosed in the present invention, the pressing force between the riveted parts can be increased, and the occurrence of looseness between the riveted parts can be avoided.

In addition, as shown in fig. 3A to 3D, an annular groove 34 may be opened along the bottom circumference of the tapered portion 32. The groove 34 has an outer diameter and an inner diameter as viewed in the axial direction of the tapered portion 32. The outer diameter of the groove 34 is the diameter of the circle corresponding to the outer edge of the groove 34. The inner diameter of the groove 34 is the diameter of the circle corresponding to the inner edge of the groove 34. The initial outer diameter (i.e. the outer diameter before undeformed) a of the peripheral wall 11 of the punch 10 of the rivet is either slightly larger than the outer diameter of the groove 34 or is intermediate the outer and inner diameters of the groove 34.

Specifically, as shown in fig. 3C and 3D, the groove 34 may have a circular arc-shaped cross-sectional profile, and the radius R of the circular arc-shaped cross-sectional profile may be 5% to 10% of the wall thickness of the peripheral wall 11 of the rivet to be punched. In one example, the wall thickness of the peripheral wall 11 of the rivet to be punched is 1mm, the distance R from the center O of the circular-arc cross-sectional profile, which has a radius R of 0.05mm to 0.1mm, to the axis of the punch 3 (i.e. the axis of the cone) is 2mm and the distance h from the end face 33 of the punch 3 is 0.1 mm.

At the end of the punching process of the rivet using the punch 3 of the present invention, the peripheral wall 11 of the punched hole 10 of the rivet is expanded outward by being punched by the punch 3 and forms the flange 12, and the flange 12 reaches the groove 34. At this time, the groove 34 may act as a buffer (i.e., allow the flange 12 to deform in the groove 34) and guide for the material forming the flange 12, so that the flange 12 is smoothly deflected along the groove 34 toward the end face 33 of the punch 3, and a rivet head of uniform shape and size is finally formed.

On the other hand, the inventors found that if the groove 34 is not opened, the flange 12 cannot be smoothly deflected toward the end face 33 of the punch 3 in some cases, but buckles and accumulates at the bottom end circumference of the tapered portion 32, i.e., at the intersection of the tapered portion 32 and the end face 33. As a result, the shape and size of the finally formed rivet head may be uneven, and even breakage may occur, failing to ensure a sufficiently large pressing force between the riveted parts.

As shown in fig. 3C and 3D, a part of the groove 34 opens on the side face of the tapered portion 32, and another part of the groove 34 opens on the end face 33 of the punch 3. In other words, the groove 34 is concave with respect to both the side surface of the tapered portion 32 and the end surface 33. The inventors have found that, with such a configuration, it is advantageous for the flange 12 to be smoothly deflected and deformed toward the end face 33 of the punch 3 along the groove 34.

On the other hand, as shown in fig. 3C, the apex angle of the tapered portion 32 may be 90 ° to 150 °, and is preferably 120 °. It will be understood by those skilled in the art that the size of the apex angle of the tapered portion 32 can be appropriately selected according to actual needs.

In both cases, where the groove 34 is open and where the groove 34 is not open, the diameter of the bottom end of the tapered portion 32 may be slightly smaller than or equal to the initial outer diameter a of the peripheral wall 11 of the punch 10 of the rivet, or slightly larger than the initial outer diameter a of the peripheral wall 11 of the punch 10. In this way, it is possible to ensure that the flange 12 formed by the peripheral wall 11 can be pressed against the end face 33 of the punch 3 at the later stage of the punching process of the rivet using the punch 3, in other words, that the end face 33 of the punch 3 can apply pressure to the flange 12.

Conversely, it will be appreciated that if the diameter of the bottom end of the tapered portion 32 is much greater than the initial outer diameter a of the peripheral wall 11 of the punch hole 10 of the rivet, the flange 12 may not sufficiently extend to the end face 33 of the punch 3 at the end of the punching process performed on the rivet using the punch 3, with the result that the end face 33 (and the groove 34) cannot function, thereby losing the meaning of providing the end face 33 (and the groove 34).

As shown in fig. 3A to 3D, the tapered portion 32 may be a truncated tapered portion, i.e., a truncated cone. The diameter of the top face of the truncated cone is smaller than the initial inner diameter B of the punch 10 of the rivet, and the height of the truncated cone is smaller than the depth c of the punch 10 of the rivet (see fig. 1B). This facilitates the tapered portion 32 to be smoothly pressed into the pierced hole 10 of the rivet for the caulking process.

The technical objects, technical solutions and technical effects of the present invention have been described in detail above with reference to specific embodiments. It should be understood that the above-described embodiments are exemplary only, and not limiting. Any modification, equivalent replacement, improvement and the like made by those skilled in the art within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A punch for punching a rivet provided at least one end with a punched hole surrounded by a circumferential wall, wherein,

the punch includes a tapered portion and a body having an end surface surrounding and connected to a bottom end of the tapered portion having a larger diameter, and the bottom end of the tapered portion has a diameter larger than an initial inner diameter of a punched hole of the rivet so that the peripheral wall extends radially outward and bears against the end surface of the body as the tapered portion is pressed into the punched hole of the rivet.

2. The punch according to claim 1, wherein,

the diameter of the bottom end of the conical portion is slightly smaller than or equal to or slightly larger than the initial outer diameter of the circumferential wall of the rivet.

3. The punch according to claim 1, wherein,

and a groove is formed at the joint of the bottom end of the conical part and the end face of the main body.

4. The punch according to claim 3, wherein,

the initial outer diameter of the peripheral wall of the rivet, viewed in the axial direction of the conical portion, is slightly larger than the outer diameter of the groove, or is intermediate between the outer diameter and the inner diameter of the groove.

5. The punch according to claim 3, wherein,

the groove is recessed relative to both the side surface of the tapered portion and the end surface of the body.

6. The punch according to claim 3, wherein,

the groove has a circular arc-shaped cross-sectional profile.

7. The punch as recited in claim 6,

the radius of the circular arc-shaped cross-sectional profile is 5% to 10% of the wall thickness of the circumferential wall of the rivet.

8. The punch according to claim 1, wherein,

the apex angle of the tapered portion is 90 ° to 150 °.

9. The punch as recited in claim 8,

the cone apex angle of the conical portion is 120 °.

10. The punch according to claim 1, wherein,

the cone is a truncated cone having a top surface with a diameter less than the initial inner diameter of the rivet punch and a height less than the depth of the rivet punch.

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