JPS62279033A - Bead forming method for pipe for piping - Google Patents

Abstract

PURPOSE:To improve a sealing property and to reduce a bead forming cost by forming the 1st bead close to a thin end edge part and cutting the end edge inner periphery thinly, then forming the 2nd bead by pressing the thin end edge part. CONSTITUTION:After performing the beveling of the end face of the pipe 1 cut in the prescribed length, the pipe end part is gripped by a holder 21 to press a die 22 in the arrow mark F direction. In this case, the 1st bead 2 and insertion part 3 are formed at the inner side from the pipe end edge of t he insertion part 3. A thin wall part 4b is then formed by cutting the pipe end edge inner periphery 4a of the insertion part 3, the rear part of the 1st bean 2 of the pipe 1 is gripped by a holder 24 and the thin wall part 4b is pressed by a die 25. In this case, the thin wall part 4b is expanded and the 2nd bead 4 is formed. In this way the forming cost of the 2nd bead is reduced and the sealing property of the pipe is improved as well.

Description

Detailed Description of the Invention 3 Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of forming a bead in a plumbing pipe. More specifically, in piping that constitutes a refrigerant circuit or a hydraulic circuit, a first bead for connection and a second bead for preventing the O-ring from slipping out are formed at the end of the pipe for connection to refrigerant equipment or hydraulic equipment. Concerning how to form.

[Prior Art] A piping pipe (50) conventionally used in a refrigerant circuit or a hydraulic circuit is configured as shown in FIG.

The pipe end portion of the plumbing pipe (50) is pressurized with a die to form a bead portion (51), and the portion on the tip side becomes an insertion portion (52) to be inserted into the mating fitting (60). ing. The insertion part (52) has an O-ring (53) for sealing.
is fitted, and the nut (54) is attached to the mating fitting (60).
When firmly screwed into the threaded part (61) of the O ring (53
) is the inner wall (62) of the mating fitting (60) and the pipe (50)
The bead portion (51) is pressed and sealed.

By the way, when assembling the conventional pipe (5o) to the mating metal fitting, the O-ring (53) is inserted into the insertion part (5o) in advance.
52), it will be damaged each time at the assembly site.
Fitting the ring (53) is very complicated. Therefore, the O-ring (53) is usually attached to the insertion portion (52) in advance.
), the pipe (50) is transported to the assembly line, where it is assembled directly into the mating part.

However, since the insertion part (52) of the pipe (50) is a short cylindrical member with the same diameter, it may be damaged due to vibration or contact with other parts while being transported to the pipe (50) assembly line.
The ring (53) may fall off. Moreover, when a worker assembles the pipe (50) at the assembly site, the insertion part (52) is hidden by the nut (54), so the worker may not notice that the O-ring (53) has fallen off. Even with careful attention, there are limits to detecting omissions.

For these reasons, it is difficult to completely eliminate the occurrence of assembled products with O-rings falling off, but once a product with a falling O-ring begins to be used in the market, leakage may occur due to the effects of vibration and heat. 0, as this may lead to unexpected accidents.
Preventing rings from falling off has long been one of the major issues to be solved.

Under the above circumstances, it has been known for a long time that if the front edge of the insertion portion (52) is slightly bulged, the O-ring (53) can be easily prevented from falling off.

Therefore, various processing methods have been tried in the past to form such a bulge. For example, in the method shown in FIG.
72) to form a bulge.

In addition, the method shown in FIG.
This is a method of hitting the front edge of 52) with a punch (74).

[Problems to be solved by the invention] However, in the conventional processing method shown in FIG.
52) must be held with the holder (71),
Since the holder (71) must be a split type holder as shown in FIG. 7, after processing, there will be sharp scratches (5) extending in the axial direction on the surface of the insertion portion (52) as shown in FIG.
5) will be added. This scratch (55) is the O-ring (53)
) is fitted into the insertion portion (52), a gap is created on the inner circumferential surface of the O-ring (53), which causes the problem of leakage no matter how strongly the nut (54) is tightened.

Furthermore, in the conventional processing method shown in Fig. 9, a punch (74
) is applied to the entire insertion portion (52), it is difficult to form a bulge only on the front edge;
2) Problems occur such as irregular bulges and irregular roundness. Therefore, even if this processing method is used, the seal will be incomplete.

In addition to the above, various processing methods have been tried, but they have not been able to solve the problems such as not being able to secure sealing properties or significantly increasing the number of man-hours. Although it has been found to be effective, pipes with such end shapes have not been put into practical use for a long time.

In view of the above circumstances, an object of the present invention is to provide a bead forming method that does not reduce sealing performance and requires less man-hours when forming a bead on the leading edge of a tube end that is effective in preventing the O-ring from falling off. do.

[Means for Solving the Problems] The present invention is a method of forming a first bead for coupling and a second bead for preventing the O-ring from slipping out at the end portion of a plumbing pipe, comprising: a) Step (A) of forming a first bead slightly inside the tube edge of the vibrator, +b) Step (B) of forming the inner periphery of the tube edge of the pipe into a thin wall by cutting, (C) The thin wall The method is characterized by comprising a step (C) of applying pressure to the part and expanding it in the radial direction to form a second bead.

In the present invention, step (B) must be performed as a pre-step to step (C), but either step (A) or step (B) may be performed first. Also, the process (C
The formation of the second bead in ) is carried out by compressing the interstory portion in the axial direction or applying pressure from the inside of the pipe using hydraulic pressure.

[Function] In the present invention, the portion formed thin in step (B) is more easily deformed than the portion having the original thickness. Therefore, when pressure is applied in step (C), only the thin portion deforms in the radial direction to form a second bead, and the thick portion does not deform.

Moreover, in step (C), the first
Since the pipe can be held by gripping the trailing edge of the beat with the holder, there is no need to grip the portion corresponding to the insertion portion with the holder, and there is no damage caused by gripping with the holder.

As described above, in the present invention, the second bead for preventing the O-ring from slipping out can be formed without deforming or damaging the outer periphery of the tube end where the O-ring is fitted.

[Example] Next, the present invention will be explained in detail.

Figures 1a to 1h are process diagrams of the method according to Example 1 of the present invention, Figure 2 is a sectional view of the end portion of a pipe formed by the method of the present invention, and Figure 3 is the external appearance of the end portion of the pipe. Figures 4b to 4d are process diagrams of a method according to Example 2 of the present invention.

Example 1 A bead forming method according to Example 1 of the present invention will be explained in order of steps with reference to FIGS. 1a to 1h.

■ Preparation process First, cut the pipe (1) to the specified length (Figure 1a),
Chamfer the end face (Figure tb).

■Step (A) Grasp the end of the pipe (1) with the holder (21) (Fig. 1c) and press the die in the direction of the arrow (P) (first
d). Through this step, a first bead (2) and an insertion portion (3) are formed slightly inside the pipe end edge of the pipe (1) (Fig. 1e).

Note that the first bead (2) in this step (A) may be formed by any conventional method other than the above.

(2) Step (B) In this step, the inner periphery (4a) of the end edge of the insertion portion (3) is removed by cutting to form a thin wall portion (4b) (Fig. 1f').

The cutting process in this step can be performed using a machine tool such as a lathe, but since the pipe (1) can be held by grasping the rear of the first bead (2), the insertion formed in step (^) Part (3) will not be damaged.

The width (v) and thickness 1) of the thin portion (4b) are appropriately selected according to the width and height of the second bead (4) to be formed.

■Process (C) In this process, after the first bead (2) of the pipe (1) -
8. Grasp one side with holder Q4 and press the tip of the insertion part (3) with a die in the axial direction (arrow (P) direction) of the pipe (1) to compress the thin part (4b) 1g figure).

Through this process, the thin wall portion (4b) swells in the radial direction, and a second bead (4) is formed (FIG. 111).

In this step, when pressed with the die 4, only the thin wall portion (4b) is deformed, and the thick wall portion is not deformed. Also, for that reason, you can use a holder etc. to attach the pipe (
There is no need to grasp the insertion part (3) to hold the
The pipe (1) can be gripped by bringing the holder Q4 into contact with the rear edge of the first bead (2). Therefore, the surface of the insertion portion (3) will not be scratched, which is likely to occur when the insertion portion (3) is gripped with a holder or the like.

In the step (C), pressure may be applied to the thin wall portion (4b) from the inside to the outside using hydraulic pressure or the like to swell it in the radial direction to form the second bead (4).

In Figure 2, the first bead (2
) and a second bead (4) are shown at the end of the pipe (1). This pipe (1) is an example of manufacturing, and the material is aluminum, the front width (1,) of the insertion part (3) is 7.0 mm, and the width of the second bead (4) (V
) is 3.55 mm, and the width of the insertion part (3) other than the bead part <
I) ) is 3.45 mm, and the outer diameter of the insertion portion (3) (
old) is 14.48 mm, inner diameter (d2) is 10.85
11111% The outer diameter (d3) of the second bead part (4) is 15
．． 55 order, the inlet inner diameter (d4) of the second bead part (4) is 1
2.30 mm. In other words, in this pipe (1), the raised height of the second bead (4) and the insertion portion (3)
The height from the surface of the second bead (4) to the top surface of the second bead (4) is approximately 0.
It is 55t+e. Depending on its height, the insertion section (
3) is sufficiently prevented from falling off.

FIG. 3 shows a pipe (1) whose end portion is inserted into a mating metal fitting (goods). According to the invention, the second bead (4)
Since the end edge of the pipe (1) is swollen, if you prepare a mating fitting (10) with an inner surface that matches the shape, the second bead (
Ensure that the distance (D) between the area where the top surface of 4) contacts and the area where the front end surface of the mating metal fitting (roller) contacts the first bead (2) of the pipe (1) is an appropriate dimension. This makes it possible to prevent the pipe (1) inserted into the mating fitting (toward) from wobbling, and also allows the O-ring (5) fitted into the insertion part (3) to tighten against the mating fitting (toward). It is in close contact with the inner wall, thereby maintaining good sealing performance. Therefore, the pipe (1) can be attached to the mating fitting by screwing the nut (6) into the threaded part of the mating fitting, just as with conventional pipes.

Moreover, in the present invention, the insertion part (3) of the pipe (1) does not lose its roundness and is not damaged as described above, so
Extremely high sealing power can be exhibited without deteriorating the sealing performance of the ring (5).

Example 2 In the above example, the thin part forming step (B) was performed after the first bead forming step (A), but this was reversed,
The thin portion forming step (B) may be performed first, and the first bead forming step (^) may be performed later.

This second embodiment will be explained based on FIGS. 4b to 4d.

(2) Preparation Step As in the case of Example 1, the pipe (1) is cut and the end surface is chamfered.

■Step (B) Following the chamfering of the end face, the inner periphery (4a) of the end edge is scraped off by cutting to form a thin wall part (4b) (4th b)
figure). If this step (B) is performed following the chamfering step, the pipe (
1) Since the main step (B) can be started from the attached state, there is an advantage that the number of work steps can be streamlined.

■Step (A) Grasp the end of the pipe (1) with the holder (21) (Fig. 4c) and press the die n in the direction of the arrow (P) (4th
d). Through this process, the first bead (2) and the insertion part (3)
) is formed.

(2) Step (C) This step and subsequent steps are carried out in the same manner as in Example 1.

Through the above steps, the second to third
The first bead (2) and the second bead (4) as shown in the figure.
You can walk through the pipe (1) with

[Effects of the Invention] According to the present invention, high sealing performance can be maintained,
A bead for preventing the O-ring from slipping out can be formed on the front edge of the pipe end of a piping vibe with a small number of man-hours.

[Brief explanation of drawings]

Figures 1a to lb are process diagrams of the method according to Example 1 of the present invention, Figure 2 is a sectional view of the end portion of a pipe formed by the method of the present invention, and Figure 3 is the external appearance of the end portion of the pipe. 4b to 4d are process diagrams of the method according to the second embodiment of the present invention, FIG. 5 is an external view of the end portion of a conventional pipe, and FIG. 6 is an explanatory diagram showing a conventional bead forming method. FIG. 7 is a perspective view of the holder shown in FIG. 6, FIG. 8 is an explanatory view of scratches caused in the insertion portion, and FIG. 9 is an explanatory view showing a conventional bead forming method. (Main symbols in the drawings) (1): Vibrator (2): First bead (3): Insertion part (4): Second bead [5): O-ring patent applicant Nichiwa Rubber Industries Co., Ltd. -1ζ - Sai18 Figure 2 Figure 5 Figure 76 Off figure; P9 figure procedural correction written type) % formula % Relationship with the case of a person who corrects the method of forming a bead on a plumbing pipe Patent applicant address Edo, Chuo-ku, Kobe City, Hyogo Prefecture Town 98 address name
Nichiwa Rubber Industry Co., Ltd. Representative Yasushi Mizukami Year 1, 18 Rijin 〒540 6 Subject of amendment (1) Contents of amendment in column 7 of "Brief explanation of drawings" of specification (1) Page 14 of specification 10 lines from the bottom “1a-1b
1a-1h. that's all

Claims (1)

[Scope of Claims] 1. A method for forming a first bead for coupling and a second bead for preventing O-ring from slipping out at the end of a plumbing pipe, the method comprising: (a) a pipe end edge of a pipe; Step (A) of forming a first bead slightly on the inner side; (b) Step (B) of forming a thin inner periphery of the end edge of the pipe by cutting; (c) Pressurizing the thin wall portion; A method for forming a bead for a plumbing pipe, comprising the step (C) of expanding in the radial direction to form a second bead. 2 The steps include step (A), step (B), and step (C).
Claim 1 characterized in that the first claim is carried out in the order of
The bead forming method described in . 3. The bead forming method according to claim 1, wherein the steps are performed in the order of step (B), step (A), and step (C).