JP3313413B2 - Punch and method for drilling hollow square pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal working punch for making a circular or square hole in a side surface of a hollow square pipe and a method for drilling the same, and more particularly, to a circular or square side hole in a hollow square pipe without using a cored bar. And a machining method.

[0002]

2. Description of the Related Art It is a frequent practice to make a hole in a side surface of a hollow square pipe to connect the pipe or insert other parts, and for example, a processing as shown in FIGS. The method is general. Referring to FIG.
In order to form a circular hole in the punch 5 using a punch 64, upper and lower dies 61 and 62 are prepared, and a series of punches 6
4 as well as a core 63 to be inserted into the hollow square pipe 65 and to receive the punch 64 in the lower mold 62.

As shown in FIG. 5, in a state (A) before perforation, a hole 68 slightly larger than the outer diameter of the edge 66 at the lower end of the punch 64 is provided in the cored bar 63. When the punch 64 is lowered to the state shown in FIG. 3B, the edge 66 penetrates the wall surface of the hollow pipe 65 to form a hole 70, and the punched metal piece 72 falls.

FIG. 6 shows a conventional method for forming a square hole in a hollow square pipe 85 by using a punch 84, in which upper and lower molds are prepared and inserted into the hollow square pipe 85 in a lower mold. Then, the core bar 83 for receiving the punch 84 must be set. In the state (A) before perforation in FIG. 6, the core bar 83 is provided with a concave groove 88 slightly larger than the outer shape of the edge 86 at the lower end of the punch 84. When the punch 84 is lowered to the state shown in FIG.
Penetrates the wall surface of the hollow pipe 85 to form a hole 90, and the punched metal piece 92 falls.

In the conventional mold structure, particularly when the square pipe is long and a plurality of holes are drilled at the same time, extra work steps are required when attaching and detaching the square pipe to the core of the mold. Because of this and the need for precision and man-hours to manufacture the cored bar,
There are drawbacks such as an increase in cost. Further, FIG.
In this case, if the outer diameter of the hole 70 to be drilled (the outer diameter of the edge 66) is close to the inner width of the hollow square pipe 65, it becomes impossible to make the hole 68 in the core 63,
The core metal will be damaged during processing. Furthermore, since the periphery of the holes 70 and 90 is deformed and burrs are generated on the inner surface after processing, it is not easy to pull out the hollow square pipes 65 and 85 from the core metal due to the burrs or the like. However, there is a disadvantage that a separation step is required.

[0006]

SUMMARY OF THE INVENTION The main object of the present invention is to form a circular or square hole in a hollow square pipe.
An object of the present invention is to simplify processing steps and speed up work. Another object of the present invention is to eliminate the need for a metal core when machining a circular or square hole in a hollow square pipe, thereby reducing the manufacturing cost and the number of machining steps.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a punch for making a hole in a side surface of a hollow square pipe, and the edge of the tip of the punch decreases in width as it goes forward. a tapered V-shaped central pointed portion therewith is composed of a continuous cylindrical portion, said V-shaped central tip
End portion exhibits a linear and cross-sectional circumference of the V-shaped central tip portion is the same outer diameter as the cylindrical portion, the punch
By changing the amount of penetration
From a hole to a roughly square hole with a large width, and even a circular hole
This is achieved by a hollow square pipe drilling punch that can be machined.

When a punch for punching having such a structure is used,
When the punch penetrates into the square pipe, the tapered V-shaped central point first penetrates, and the tapered edge pushes the wall to the left and right, forming a straight line with the partially arcuate cut surface. A substantially rectangular hole formed by the pressed part is formed. Subsequently, as the punch penetrates, the width of the partial arc-shaped cut surface increases, and when the cylindrical portion of the punch begins to penetrate the wall surface, a circular hole is formed. Since a series of these drilling operations are performed instantaneously, if the distance for lowering the punch is reduced, the drilling operation is completed with a small width approximately square hole, and the punch is lowered.
If you increase the distance slightly, a roughly square hole with a large width
The drilling operation is completed in the state where the hole is opened , and if the distance for lowering the punch is further increased , the drilling operation is completed with the circular hole formed.

In such a series of operations, a high-precision and high-rigidity core metal is not required as in the prior art, and the lower mold may be a simple one. Thus, the cost of manufacturing the core is reduced, and the mold is simplified and the cost is reduced. The time required for inserting and removing the metal core is not required, and the work time is shortened and the efficiency is improved. Since the shearing press force required for drilling holes is smaller than before by gradually shearing, the pressing force used can be smaller and the cost can be further reduced.

The present invention relates to another embodiment of the punch,
Punch tip edge, the tapered V-shaped central tip portion width decreases toward the first, therewith consists of a continuous prismatic portion, the same depth as the V-shaped depth of the central tip portion said prismatic portion Provide a punch for drilling hollow square pipe sized.

When a punch for punching having such a structure is used,
As the punch penetrates into the square pipe, the tapered V-shaped central point first penetrates, and the tapered edge pushes the wall to the left and right, so that the punch cuts straight and parallel A rectangular hole consisting of the pressed part is formed. Subsequently, as the punch penetrates, the width of the parallel linear cut surface increases, and when the prismatic portion of the punch begins to penetrate the wall surface, a square hole is formed. These series of drilling operations are performed instantaneously, so if the distance for lowering the punch is reduced, the drilling operation is completed with a small square hole, and if the distance for lowering the punch is increased, the large square hole is reduced. The drilling operation is completed in a state in which is formed.

The present invention further provides a method for punching a hole in a side surface of a hollow square pipe without inserting a metal core into the hollow square pipe using the above-described punch.
By using this method, the speed of the drilling process can be increased and the operation cost can be reduced. Other features and advantages of the present invention will become apparent from the following description with reference to embodiments of the accompanying drawings.

[0013]

1 shows a punch 10 for drilling according to the present invention.
And a hollow square pipe 20 such as a steel pipe. The punch 10 is a shank 11 for holding with a chuck.
And an edge 12 at the tip. The edge 12 at the tip of the punch has a tapered V shape whose width decreases as it goes forward.
A central central point portion 13 and a continuous cylindrical portion 14
It is composed of The square pipe 20 is set in a mold 25 having a simple shape.

FIG. 1A shows a punch 10 and a hollow square pipe 2.
0, and FIG. 1B is a bottom view of the punch 10 as viewed from below (W direction). V
As shown in FIG. 1 (B), the distal end of the
It has a linear shape. Figure 1 (C) (D) ( E) represents the cross-sectional shape of the punch each cross section of the shank 11 is circular larger outer diameter, circular outer diameter smaller cross section than that of the cylindrical portion 14, a central pointed portion The cross section of 13 has parallel straight side surfaces 13A, 13B and partial arc-shaped cut surfaces 13C, 1C.
3D. Circular cut surfaces 13C, 13D
Are continuously formed so as to have the same outer diameter as the outer diameter of the cylindrical portion 14.

FIG. 2 shows a step of processing a hole using the punch 10 of FIG. In the process A, the punch 1
The center point of 0 starts to penetrate the hollow square pipe 20. When the punch 10 is lowered to the position B, the tapered V-shaped central point portion 13 penetrates while forming the bent portion 21 so as to push the wall surface of the pipe 20 right and left. In the state of step B, the pipe 20
A substantially square hole as shown in FIG.

When the punch 10 is further lowered to the position C, the cylindrical portion 14 of the edge penetrates into the hollow square pipe 20 to form a circular hole as shown in FIG. The bent portion 21 remaining on the
And let it fall. If the lowering of the punch 10 is stopped in the state shown in FIG. 2B, a substantially rectangular hole can be freely formed from a small width to a large width, and the advantage that the applicable range of the punch is widened is obtained. Can be

FIG. 3 shows another embodiment of the present invention, in which a square hole can be formed in a side surface of a hollow square pipe using a punch. The punch 30 is composed of a shank 31 for holding by a chuck and a leading edge 32. The leading edge 32 of the punch has a tapered V-shaped central point portion 33 whose width decreases as going forward, and a continuous portion thereof. And a prism portion 34. Square pipe 4
0 is set in a mold having a simple shape.

FIG. 3A shows a punch 30 and a hollow square pipe 4.
0, and FIG. 3B is a bottom view of the punch 30 as viewed from below (P direction). 3 (C), (D) and (E) show the cross-sectional shapes of the punch, respectively.
The cross section of the prism portion 34 is quadrangular, and the cross section of the central point portion 33 is formed by parallel straight side surfaces 33A and 33B and parallel straight cut surfaces 33C and 33D. The depth dimension of the V-shaped central point portion 33 is continuously formed so as to be the same as the depth dimension of the prism portion 34.

The process of forming a hole using the punch 30 of FIG. 3 is the same as the process shown in FIG. 2. In the first step, the central point of the punch 30 starts to penetrate the hollow square pipe 40. When the punch 30 is lowered to the next position,
The tapered V-shaped center point portion 33 penetrates while forming a bent portion so as to push the wall surface of the pipe 40 right and left. In this state, a square hole as shown in FIG. 3E is formed in the pipe 40.

When the punch 30 is further lowered to the next position, the prism portion 34 of the edge penetrates into the hollow square pipe 40 to form a square hole as shown in FIG. The remaining bent portion is separated into pieces and dropped. If the lowering of the punch 40 is stopped in the same state as shown in FIG. 2B, a square hole can be freely formed from a small width to a large width.
The advantage that the application range of the punch is widened is obtained.

[0021]

As described above in detail, according to the present invention, by changing the amount of penetration of the punch, a small width can be obtained.
From a square hole to a large square hole with a large width, and even round
Can process up to holes. A high-precision and high-rigidity core metal is not required as in the related art, and the lower mold may be a simple-shaped mold. Thus, the cost of manufacturing the cored bar is reduced, and the mold is simplified to reduce the cost. The time required for inserting and removing the metal core is not required, and the work time is shortened and the efficiency is improved. Since the shearing press force required when drilling holes can be smaller than before, the press used requires less pressing force, and further advantages such as cost reduction can be obtained. Some of the effects are quite significant.

[Brief description of the drawings]

1A and 1B are a perspective view and a cross-sectional view of a punch, respectively, showing a method of making a hole using a punch according to the present invention. 1A is a perspective view, FIG. 1B is a bottom view from W, FIG. 1C is a horizontal cross-sectional view along line X, FIG. 1D is a horizontal cross-sectional view along line Y, and FIG. 1E is a horizontal cross-sectional view along line Z. .

FIG. 2 is a schematic sectional view showing a drilling step according to the present invention. FIG. 2A, FIG. 2B, and FIG. 2C show each process.

3A and 3B are a perspective view and a cross-sectional view illustrating a punching method using a punch according to another embodiment of the present invention. FIG. 3A
3B is a perspective view, FIG. 3B is a bottom view seen from P, FIG. 3C is a horizontal sectional view along line Q, FIG. 3D is a horizontal sectional view along line R, FIG.
E is a horizontal sectional view along line S.

FIG. 4 is a perspective view illustrating a method of drilling according to a conventional example.

FIG. 5 is a schematic longitudinal sectional view showing a hole making method according to a conventional example. FIG. 5A shows a state before drilling, and FIG. 5B shows a state after drilling.

FIG. 6 is a schematic longitudinal sectional view showing a method for drilling according to another conventional example. FIG. 6A shows a state before drilling, and FIG. 6B shows a state after drilling.

[Explanation of symbols]

10,30 punch 11,31 shank 12,32 edge 13,33 V-shaped central point 14,34 cylindrical part 20,40 hollow square pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-263832 (JP, A) JP-A-48-30185 (JP, A) Fully open 63-150716 (JP, U) Really open Showa 58- 137521 (JP, U) Japanese Utility Model Showa 59-6013 (JP, U) Japanese Patent Publication No. 49-9305 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21D 28/24 B21D 28 / 28 B21D 38/34

Claims (2)

(57) [Claims] 1. A punch for making a hole in a side surface of a hollow square pipe, wherein the edge of the punch tip has a tapered V-shaped central point having a width decreasing as it goes forward, and a cylindrical portion continuous therewith. And the end of the V-shaped central point portion is a line
And the outer periphery of the cross section of the V-shaped central point portion has the same outer diameter as the cylindrical portion, which changes the amount of punch penetration.
By letting a small width approximately square hole through a large width
A punch for drilling hollow square pipes, characterized in that it can be processed into a substantially square hole and even a circular hole . 2. A method of punching a hole in a side surface of a hollow square pipe without inserting a metal core into the inside of the hollow square pipe, wherein the edge of the tip has a tapered shape whose width decreases as it goes forward. It is composed of a V-shaped central point and a continuous column, and the end of the V-shaped central point has a linear shape.
A punch having a cross-sectional periphery of the V-shaped center point portion having the same outer diameter as the cylindrical portion is prepared, and the punch is penetrated by a predetermined distance into the hollow square pipe to obtain a small-width substantially square shape. Hole or short for large width
A method for drilling a hollow square pipe, characterized by drilling a square hole or a circular hole .