JPH09201627A - Burring punch and burring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burring punch for forming a burring shape having a projecting part without necking for securing rigidity. SOLUTION: A prepared hole working part 12 and a burring hole working part 13 are formed on the burring punch 11, a 1st square pyramid-shaped working part 12a having adjacent plural inclined working surfaces 12c is formed and the 2nd columnar working part 12b is formed continuously to the 1st working part 12a in the prepared hole working part 12. Chamfering parts 12d are formed from the halfway of each edge line R formed with plural adjacent inclined working surfaces 12c toward the side of the 2nd working part 12b. A radius part 13a where is continued from the prepared hole working part 12a is formed in the columnar burring hole working part 13 having a diameter larger than that of the 2nd working part 12b.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a burring process,
In particular, by performing ironing continuously after breaking through the prepared hole, a cylindrical burring (also called "Hatome" or "hole flange" etc.) on a metal flat plate without producing metal scrap in one step The present invention relates to a burring punch used in a burring process for molding a burring and a burring shape molded by the burring punch.

[0002]

2. Description of the Related Art Conventionally, a burring process for forming a cylindrical burring on a metal flat plate without producing metal scraps in one step by continuously performing ironing process after piercing a prepared hole has been performed as shown in FIG. A burring punch 1 as shown in (A) to (C) is used.

This burring punch 1 has a polygonal pyramid-shaped first processing portion 2a and a cylindrical second processing portion 2b having a sharp tip.
The prepared hole processing part 2 having a and the burring hole processed part 3 continuous from the second processed part 2b are integrally formed.

The first processed portion 2a is formed into a quadrangular pyramid by adjoining the triangular inclined processed surfaces 2c, 2c ... To the respective sides so that the respective surfaces are orthogonal to each other.

The burring hole processing portion 3 is the second processing portion 2b.
It has a cylindrical shape with a larger diameter than
An R portion 3a is formed in a portion continuous with b.

In such a burring punch 1, as shown in FIG. 5A, a metal plate 5 is placed on the die 4 and the burring punch 1 is lowered.

Then, the prepared hole is first formed in the metal plate 5 by the first processed portion 2a, and the prepared hole is gradually opened by the R portion 3a while the prepared hole processed state is maintained by the second processed portion 2b. As shown in FIG. 5B, when the burring punch 1 reaches the bottom dead center, the burring hole 5 a is formed by the burring hole processing portion 3.

At this time, as shown in FIG. 6 (A), when the metal plate 5 is pierced with the first processed portion 2a, it is formed at the boundary between the ridge of the first processed portion 2a and the second processed portion 2b. The side P to be cut serves as a cutting edge, and as shown in FIG. 6B, a crack C ′ extending in the circumferential direction is formed separately from the cross-shaped crack C formed by the first processed portion 2a (see arrow).

Therefore, the metal plate 5 after the burring process is completed
As shown in FIG. 6 (C), a burring-shaped burring 5c including a cylindrical portion 5a and four substantially diamond-shaped convex portions 5b, 5b ... Is formed. The cylindrical portion 5a
The rising edge of is formed by the R portion 3a.

[0010]

By the way, in the shape of the burring 5c formed by the burring punch 1 configured as described above, the ridge 5d is formed at the base of the convex portions 5b, 5b ... , 5d ... are not formed, the rigidity of the convex portions 5b, 5b ... Is not ensured. For example, when the parts (barred) are stacked or stacked, the weight of the parts or the time of transfer There is a problem that the convex portions 5b, 5b ...

At this time, the protrusions 5b, 5b ... Are often collapsed inside the burring 5c because the burring shape is cylindrical, and the protrusions 5b, 5b ... Are collapsed inside the burring 5c. If this happens, the burring 5c will be blocked.

Further, when the burring 5c is processed, a crack C'which is a factor for forming the constriction 5d may cause a crack in the convex portion 5b.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a burring punch capable of forming a burring shape having a convex portion without a constriction in order to ensure rigidity.

[0014]

In order to achieve the object, the invention according to claim 1 is such that a plurality of inclined machining surfaces are continuous to the first machining portion of a polygonal pyramid shape and the first machining portion. A prepared hole processing portion having a cylindrical second processed portion and a cylindrical burring hole processed portion having an R portion continuous from the prepared hole processed portion and having a larger diameter than the second processed portion are provided. The gist of the burring punch is that the burring punch is provided with a chamfered portion that is formed from a middle portion of each ridge line formed by adjoining the plurality of inclined processing surfaces toward the second processing portion side.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the burring punch and burring of the present invention will be described with reference to the drawings.

In FIG. 1, the burring punch 11 is
A prepared hole processing part 12 having a first processed part 12a having a polygonal pyramid shape having a sharp tip and a second processed part 12b having a cylindrical shape, and a burring hole processed part 13 continuous from the second processed part 12b are integrally formed. ing.

The first processing part 12a is formed into a quadrangular pyramid by adjoining a plurality of triangular inclined processing surfaces 12c, 12c, ... The chamfered portions 12d, 12d ... Are formed from the midway portion of each ridge line R formed by the adjacent surfaces 12c, 12c. In addition, the chamfered portion 12d is adjacent to the inclined processed surface 12
It is symmetrical about the ridgeline R with respect to c and 12c.

The burring hole processing section 13 is the second processing section 1
It has a cylindrical shape with a diameter larger than 2b, and the second processing portion 1
An R portion 13a is formed in a portion continuous with 2b.

In such a burring punch 11, as shown in FIG. 2 (A), the metal plate 15 is placed on the die 14.
Is installed and the burring punch 11 is lowered.

Then, the prepared hole is first formed in the metal plate 15 by the first processed portion 12a, the prepared hole is maintained by the second processed portion 12b, and the prepared hole is gradually expanded by the R portion 13a. As shown in FIG. 2B, when the burring punch 11 reaches the bottom dead center, the burring hole 15
a is formed by the burring hole processing portion 13.

At this time, as shown in FIG. 3A, when the first processed portion 12a is stuck into the metal plate 15, the boundary between the ridge line of the conventional first processed portion 2a and the second processed portion 2b is used. Since the chamfered portion 12d is formed in the portion corresponding to the side P formed in the above, there is no cutting edge.

Moreover, since the chamfered portion 12d is formed, the inclination angle of the chamfered portion 12d toward the tip side becomes sharper (the spread from the tip becomes narrower) than the conventional inclination angle of the side P toward the tip side. Since the difference in inclination angle causes a volume difference, the remaining wall thickness W1 of the metal plate 15 along with the prepared hole machining shown in FIG. 3A is accompanied by the prepared hole machining shown in FIG. 6A. It becomes thicker than the remaining wall thickness W2 accompanying the extension of the metal plate 5. In other words, it is possible to set the clearance that accompanies the extension of the metal plate 15, and the factor that can cause the crack C ′ in combination with the absence of the cutting edge is eliminated.

Therefore, as shown in FIG. 3 (B), the prepared hole by the first processed portion 12a is only the cross-shaped crack C, and the metal plate 15 after the burring process has the structure shown in FIG.
As shown in (C), a cylindrical portion 15a protruding from a flat surface portion of the metal plate 15 and a substantially triangular shape which continuously protrudes from the cylindrical portion 15a in the same direction and has the maximum width. A burring-shaped burring 15c is formed by the four convex portions 15b, 15b. still,
The rising of the cylindrical portion 15a is formed by the R portion 13a.

As described above, the burring punch 1 of the present invention is used.
In No. 1, the chamfered portion 12d is provided in the first processed portion 12a, so that the generation of the crack C'can be prevented, and the burring 15c formed by the burring punch 11 has the conventional constriction 5d. Can be prevented, and the burring 15c can be made rigid.

[0025]

As described above, in the burring punch of the present invention, the burrs formed by the adjoining plural inclined working surfaces are formed from the middle part of each ridge line toward the second working part side. By having a chamfered part,
It is possible to form a burring shape having a convex portion having no constriction in order to secure rigidity.

[Brief description of drawings]

FIG. 1 shows a burring punch according to a first embodiment of the present invention, (A) is a front view of the burring punch, and (B) is a front view of the burring punch.
[Fig. 3] is an enlarged front view of the tip portion of the burring punch, and (C) is an enlarged bottom view of the first processing portion.

2A is a sectional view of a burring die before burring, and FIG. 2B is a sectional view of a burring die after burring.

3A is a cross-sectional view of a main part of a burring work die in a prepared hole working state, FIG. 3B is an explanatory view showing a cracked state, and FIG. 3C is a perspective view of the burring.

FIG. 4 shows a conventional burring punch, (A) is a front view of the burring punch, (B) is an enlarged front view of a tip portion of the burring punch, and (C) is an enlarged bottom view of the first processing portion.

5A is a sectional view of a burring die before burring, and FIG. 5B is a sectional view of a burring die after burring.

6 (A) is a sectional view of a main part of a burring die in a prepared hole state, FIG. 6 (B) is an explanatory view showing a crack occurrence state, and FIG. 6 (C) is a perspective view of the burring.

[Explanation of symbols]

 11 ... Burring punch 12 ... Pilot hole processing part 12a ... 1st processing part 12b ... 2nd processing part 12c ... Inclined processing surface 12d ... Chamfer part 13 ... Burring hole processing part 13a ... R part 15 ... Metal plate 15c ... Burring R ... Ridge

Claims (3)

[Claims] 1. A prepared hole processing portion having a polygonal pyramid-shaped first processed portion adjacent to a plurality of inclined processed surfaces and a cylindrical second processed portion continuous with the first processed portion, and the prepared hole processed portion. A burring punch having a cylindrical burring hole machining portion having a larger diameter than the second machining portion, the ridgelines being formed by adjoining the plurality of inclined machining surfaces. A burring punch provided with a chamfered portion formed from a middle portion toward the second processed portion side. 2. The first machining portion is a quadrangular pyramid, and the chamfered portion is symmetrical with respect to an adjacent one of the inclined machining surfaces about the ridge line. Burring punch. 3. A cylindrical portion protruding from a flat portion of a metal plate,
A burring which is formed by a plurality of substantially triangular projections each of which has a maximum width and which continuously projects from the cylindrical portion in the same direction.