JPH067855A - Punch for burring tube and method for burring - Google Patents

Abstract

PURPOSE:To make the end face of burring horizontal and to improve the strength of a brazing part by forming the drilling part elliptically at the tip end of a working punch and providing a shear angle. CONSTITUTION:The drilling part 22 of the punch body 21 is formed elliptically, and the shear angle 24 is provided at the tip end of the drilling part 22. The punch 21 is inserted so that the major axis of the ellipse is coincident with the tubular axis of a tube to be worked. When the punch 21 is protruded, an elliptic prepared hole is punched on the tube to be worked. When the punch 21 is further protruded, burring is performed by the burring part 23 on the tube to be worked and an insertion hole for a connecting tube is formed. Since the prepared hole is elliptic, the length of a rising part of burring is gradually extended in the direction from the major axis of the ellipse to the minor axis, and a horizontal plane is formed for the end face of burring. The strength of the brazing part is improved, the protruding part of the connecting tube is reduced, and the loss in the flow pressure of a fluid is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burring punch that is frequently used for connecting pipes such as pipes of refrigeration and air-conditioning equipment to pipes, and can be used in combination with punching and burring. The present invention relates to a burring punch for a tube and a burring forming method.

[0002]

2. Description of the Related Art Recently, as a burring punch used for processing a pipe, a punch used in a burring method proposed in Japanese Patent Publication No. 56-8687 has been adopted.

The conventional punch for burring a pipe and the method for forming the burring will be described below with reference to the drawings with reference to the drawings.

FIG. 6 shows a conventional burring punch. In FIG. 6, 1 is a punch main body. Two
Is a circular hole forming part, which forms a prepared hole in the pipe to be processed. Reference numeral 3 denotes a burring portion, which has a circular shape and which pushes and expands the prepared hole to perform burring processing.

The burring forming method of the burring punch having the above structure will be described below. First, the punch 1 which can be used together with the projecting hole and the burring process is inserted into the pipe 5 to be processed. Next, when the punch 1 is protruded, a prepared hole having the same diameter as the hole forming part 2 is formed in the pipe 5 to be processed by the hole forming part 2. Further, when the punch 1 is projected, the pilot hole is expanded and burred by the burring portion 3 to form the connection tube insertion hole 7.

FIG. 10 shows a state in which the connecting pipe 10 is brazed after the burring process.

[0007]

However, in the burring punch as described above, since the piercing portion 2 and the burring portion 3 are circular, the burring rising portions 6 have the same length. The burring end 8 forms an arcuate recess and is brazed by the brazing material 9 when joining the pipe 5 to be processed and the connecting pipe 10. However, by protruding the connecting pipe 10 into the pipe 5 to some extent, Gives strength to the attachment.

However, when the fluid flows into the pipe 5 to be processed, a flow pressure loss occurs at the protruding portion. Further, since the burring end 8 forms an arcuate recess, it is difficult to use a brazing wax such as a ring brazing wax.

Further, there is a problem that the workability is poor when the tip of the punched portion 2 of the punch is a horizontal surface.

The present invention solves the above-mentioned conventional problems and improves the strength of the brazed portion in the burring process of a metal pipe or the like, and reduces the protruding portion at the time of connecting pipes to each other. An object of the present invention is to provide a punch for burring and a method for forming burring, which can reduce the flow pressure loss, form a burring shape that can be used as a placement braze with stable shape quality, and have good workability.

[0011]

In order to achieve this object, the burring punch of the present invention has an elliptical hole at the tip thereof.

Further, the burring punch is provided with a shear angle at the drilled portion at the tip thereof.

Further, an elliptical pilot hole is formed by using the above burring punch, and then burring is performed to form the burring end portion on a horizontal plane.

[0014]

In the burring punch according to the present invention, since the punched portion of the punch has an elliptical shape, the length of the burring rising portion extends from the elliptical major axis direction to the elliptic minor axis direction, and the burring end portion becomes horizontal. Once formed, the strength of the braze is improved when the tubes are joined. Further, the protrusion of the pipe joint is reduced, and the flow pressure loss in the pipe is reduced when the fluid flows. Further, since the burring end surface is a horizontal surface, the workability of brazing is improved, and it becomes possible to use a brazing filler metal such as a ring brazing solder. Further, by providing the shear angle, the shear load can be reduced and the workability of the pipe can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 21 is a punch body.
Reference numeral 22 is a perforated portion that forms an elliptical shape, and 23 is a burring portion that forms a circular shape. Further, a shear angle 24 is provided at the tip of the punched portion 22.

The burring forming method of the burring punch for a tube constructed as described above will be described with reference to FIGS. First, the punch 21 is vertically movably inserted into the pipe to be processed 25 such that the major axis direction of the ellipse coincides with the axial direction of the pipe to be processed 25. Next, punch 21
When this is projected, an elliptical prepared hole similar to the drilled portion 22 is punched in the pipe 25 to be processed.

When the punch 21 is further projected, the pipe 25 to be processed is subjected to burring by the burring portion 23 to form the connection pipe insertion hole 27. At this time, as described above, when the elliptical pilot hole is removed as the pilot hole and the circular burring portion 23 is made to project, the elliptical pilot hole of the burring rising portion 26 is changed from the major axis direction to the minor axis direction. The length gradually increases and the burring end face 28 forms a horizontal plane. At this time, by providing a shear angle at the tip of the drilled portion 22, the shearing load can be reduced and the drilling of the pipe can be performed smoothly.

FIG. 5 shows a joined state of a pipe subjected to burring according to this embodiment and a joined pipe.

As described above, according to this embodiment, the perforated portion 2
By making 2 as an elliptical shape and performing drilling and burring, the length of the burring rising portion 26 gradually extends from the elliptical major axis direction of the elliptical prepared hole to the elliptic minor axis direction, and the burring end surface 28 has a horizontal plane. As a result, the strength of the brazed portion is improved.

Further, it is possible to reduce the projecting portion of the connecting pipe 30, and it is possible to obtain the effect of reducing the fluid flow pressure loss. Further, by providing a shear angle at the tip of the holed portion 22, the shear load can be reduced and the workability of the pipe can be improved.

In this embodiment, it goes without saying that the burring process can be performed by sandwiching the pipe to be processed with a punch and a die using a die.

[0023]

EFFECTS OF THE INVENTION As described above, the pipe burring punch of the present invention has the following effects.

That is, the length of the burring rising portion gradually increases from the major axis direction of the elliptical pilot hole to the minor axis direction, and the burring end surface becomes a horizontal plane, whereby the strength of the brazing portion is improved and the connecting pipe The protrusion can be reduced, and the fluid pressure loss can be reduced. Furthermore, since the burring end surface is a horizontal surface, the workability of brazing is improved and the brazing filler metal is easy to use.

Further, the shear angle at the tip of the drilled portion has the effect of reducing the shear load and improves the workability.

[Brief description of drawings]

FIG. 1A is a plan view of a burring punch according to an embodiment of the present invention. FIG. 1B is a front view of a burring punch according to an embodiment of the present invention.

FIG. 2 (a) is a cross-sectional view of an essential part of an initial step of a burring forming method according to an embodiment of the present invention (b) is a cross-sectional view of an essential part of a drilling process of a burring forming method according to an embodiment of the present invention (c) ) A cross-sectional view of the main part of the burring process of the burring method according to the embodiment of the present invention

3A is a plan view of a main part of FIG. 2A, FIG. 3B is a plan view of a main part of FIG. 2B, and FIG. 3C is a plan view of a main part of FIG. 2C.

FIG. 4 is a front view of an essential part of a pipe shape to be processed after burring according to the present invention.

FIG. 5 is a front view of a main portion where a connection pipe is joined to a pipe to be processed after burring of the present invention.

FIG. 6A is a plan view of a conventional burring punch, and FIG. 6B is a front view of a conventional burring punch.

FIG. 7A is a sectional view of an essential part of an initial step of a conventional burring forming method. FIG. 7B is a sectional view of an essential part of a boring process of a conventional burring forming method. Sectional view of the main part of

8A is a plan view of a main part of FIG. 7A, FIG. 8B is a plan view of a main part of FIG. 7B, and FIG. 8C is a plan view of a main part of FIG. 7C.

FIG. 9 is a front view of a main part of a conventional pipe shape after burring.

FIG. 10 is a front view of a main part in which a connecting pipe is connected to the pipe to be processed after the burring process in FIG.

[Explanation of symbols]

 21 Punch 22 Drilling part 23 Burring part 24 Shear angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B21D 37/08 7425-4E 39/04 A 7425-4E

Claims (3)

[Claims] 1. A punch for burring of a pipe, wherein a hole at the tip is formed in an elliptical shape. 2. A punch for burring of a pipe, wherein a shear angle is provided at a holed portion at the tip. 3. A burring forming method for forming an elliptical pilot hole using the burring punch for a pipe according to claim 1 or 2, and then performing burring to form the burring end on a horizontal plane.