JP2557763B2 - How to bulge a pipe with beads - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a bellows pipe having three beads from a thin tubular work using a rubber punch.

[0002]

2. Description of the Related Art When bulging a beaded pipe using a rubber punch, if the number of beads is set to 3, the flow of the rubber that flows into the bead at an intermediate position is reduced to a small diameter portion, that is, a valley. It is said that it is impossible to exert a molding pressure on the bead at the intermediate position due to being blocked, and it is limited to molding two beads (Masanobu Nakamura "Pipe processing method", Nikkan Kogyo Shimbun, Ltd. P.95-96). Was there. Therefore, 3
When forming a pipe having beads with more than a mountain, is mechanical molding (for example, Japanese Patent Laid-Open No. 64-2733) in which a valley is narrowed using a cored bar and a large number of pressing dies divided into two? Hydraulic molding is used to bulge the pipe material onto the die surface with hydraulic pressure.

However, since the above-mentioned mechanical forming is a drawing process, wrinkles are likely to occur. On the other hand, in hydraulic forming, since a special hydraulic device is used without using a press machine, the entire equipment becomes complicated and expensive. There is the inconvenience of being inefficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to form a pipe having three beads by using a normal press machine.

[0005]

Means for Solving the Problems According to the means for solving the problems of the present invention, a bead forming surface is provided on an inner peripheral surface, a tubular work is inserted into a die separable by a diameter line, and an internal pressure is applied to the tubular work. In a bulge forming method of a beaded pipe for forming a bead, a first step of bulging with a first die having a deep bead forming surface at a central portion and a pair of shallow bead forming surfaces on both sides thereof, and a rubber punch; Part and both sides have a deep bead molding surface, and the second die having a die part formed by dividing between adjacent bead molding surfaces and at the middle of each bead molding surface is used, and each die part is mutually The second step is to bulge by pressing the rubber punch while approaching it.

[0006]

In the above step, in the first step, the bead forming surface on both sides of the die is shallow, so the work is formed shallow in this portion, but the rubber of the punch is deep in the center along this shallow forming surface. It can flow into the surface to be molded, and both sides and the center are molded at the same time. In the second step, the rubber of the punch first flows into and fills the deep molded surface in the center formed in the first step and the shallow molded surfaces on both sides, and then the pressure is increased by the subsequent pressurization to increase the die pressure. Molding is performed by swelling the molding surfaces on both sides to deep bead molding surfaces while reducing the interval between the pieces.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 (a), (b), and (c) show a processing step of a beaded pipe having beads of three ridges, and a work 1a made of a thin-walled tube shown in (a) is a first step shown in (b). In the above, intermediate processing is carried out mainly on the center bead, and the intermediate work 1b is subjected to finishing processing on the beads on both sides in the second step shown in (c) to obtain a finished product 1c.

In FIG. 1 (b), numeral 2 is a first die, which is a semicircular die piece 3a, 3b, 4 divided at the top of the bead.
a, 4b, 5a, 5b, 6a, 6b are held in a die holder (not shown), which has a deep bead molding surface 2a at the center and both surfaces have shallow bead molding surfaces 2b, 2c.

A rubber punch 7 press-fitted into the work 1a.
Is integrally fixed to the lower punch 8, but the upper punch 9
Is not fixed to the rubber punch 7. When the rubber punch 7 is put into the work 1a and both the upper and lower punches 8 and 9 are press-fitted, the rubber punch 7 causes the inner surface of the work 1a to move to the molding surface 2a,
Pressure is applied toward 2b and 2c to form deep beads 1A in the center and shallow beads 1B and 1C on both sides.

At this time, the rubber of the rubber punch 7 moves in the axial direction and the diametrical direction, but since the molding surfaces 2b, 2c on both sides are shallow, it can be easily moved along the shallow beads 1B, 1C, and the beads are easily moved. While forming 1B and 1C, concentrate on the deep bead 1A and form the bead 1A as the primary product to obtain the semi-finished product 1
get b.

Next, the rubber punch is made to escape, and the semicircular body 3a is formed.
6a and 3b to 6b are separated, and the semi-finished product 1b is shown in FIG.
The second die 10 is used for processing. The second die 10 is also a combination of semicircular die pieces 11a to 14a and 11b to 14b, and has deep forming surfaces 10a, 10b, 1 having the same depth.
With 0c. These molding surfaces have a shape close to the deep molding surface 2a of the first die 2, whereby the deep beads 2
A, 2B and 2C are molded to obtain a work 1c.

A press 20 shown in FIG. 2, for example, is used in this second step. The press 20 has a symmetrical shape, and the left half of FIG. 2 shows before pressing and the right half shows after pressing. A lower punch 8 holding a rubber punch 7 is fixed to the center of a lower base plate 21, and die holders 24 and 25 are mounted on sliding plates 22 and 23 provided on the base plate 21 so as to be slidable in a radial direction. Placed on the base plate 21 and receiving plates 26 and 27 extending downward from the outer ends of the die holders 24 and 25,
Springs 30 and 31 are interposed between 29 to press the die holders 24 and 25 in the opening direction.

An upper punch 9 is fixed to the center of the pressure plate 32, pressure cams 33 and 34 are fixed downward on both sides thereof, and cam surfaces 35 and 36 inclined outward and a holding surface 37 perpendicular to the cam surfaces 35 and 36. , 38 are formed. And the die holder 2
Cam surfaces 39 and 40 that cooperate with the cam surfaces 35 and 36 are formed on the surfaces 4 and 25, and stoppers 41 and 4 for backing up the pressure cams 33 and 34 are provided at both ends of the base plate 21.
2 are erected. Recess 4 of die holder 24, 25
The second die 10 is installed in 3, 44, the uppermost die pieces 11a, 11b are fixed to the pressing plate 32, and the lowermost die pieces 14a, 14b are the die holders 24, 25.
It is fixed to. Then, in order to operatively connect the die pieces, the relief recesses 4 are formed in the die pieces 11a and 11b.
5 and 46 are provided below which the die pieces 12a and 12b are provided.
Holes 47, 48, 49, 50 are formed in the die part 1
Holes 51, 52, 53, 54 are formed in 3a, 13b.

Further, holes 4 are formed in the die pieces 13a and 13b.
The headed pins 55 and 56 that are locked to the upper die parts 12a and 12b through 7 and 48 are fixed, and are also locked to the lowest die parts 14a and 14b to the die parts 13a and 13b. Headed pins 57 and 58 are planted. Springs 59 and 60 passing through the holes 53 and 54 are provided between the die pieces 12a and 14a and between the die pieces 12b and 14b. An upper step 61 is formed on the upper part of the lower punch 48, and a lower step 62 is formed on the die pieces 11a and 11b.

While the pressure plate 32 is moving upward, as shown in the left half of FIG. 2, the die piece 12a is pushed up by the spring 59, so that the headed pin 55 pulls up the lower die piece 13a. The pulling amount is limited by the headed pin 57, and the die pieces 12a, 13a, 14a are held at substantially equal intervals. Similarly, the right half portion is also separated.

Here, the pressure plate 32 is further raised from the position shown in the figure, and the work 1b formed in the first step is rubber punched.
When the pressure plate 32 is lowered, the die holder 2
4 and 25 are pressed by the cam surfaces 35 and 36 of the pressure cams 33 and 34 to compress the springs 30 and 31 and reach the innermost position, and the minimum diameter portions of the die pieces 11a to 14a and 11b to 14b. Is in contact with the valley of the work 1b, and the step portions 61 and 62 are in contact with the upper and lower ends of the work 1b.

When the pressure plate 32 is further depressed, the diameter of the rubber punch 7 and the pressure applied by the step portions 61 and 62 cause the work 1
b also expands in diameter in the non-contact portion between the die pieces, but because of the presence of the beads 1A, 1B, 1C formed in the first step,
The free lowering of each die piece is restricted, and the intervals are kept close to each other while being maintained at a substantially constant ratio, and finally the upper and lower die pieces are in close contact with each other as shown in the right half, and the continuous Due to the bulging diameter of the rubber punch 7, the work 1 is attached to the molding surface of the second die 10.
b is pressure-bonded, bulging is performed, and the work 1c is formed.

At this time, the rubber punch 7 fills the beads 1A, 1B, 1C formed in the first step and then expands to form the beads 2A, 2B, 2C, but at the deep bead 1A portion. High molding resistance, low beads 1B, 1
Since the molding resistance is low in the C part, the beads 1B, 1
The rubber in the vicinity of C expands to form the beads 1B, 1C,
The rubber in the bead 1A does not move in the pressing direction.
Therefore, no shearing force in the pressing direction is generated between the peaks and valleys of the rubber punch 7 in the bead 1A. Next, when the pressure plate 32 is raised, each die piece is moved to the die holder 24,
Workpiece 1 retreats with 25 and opens a vertical gap between them
c can be taken out.

The example of pressurizing the second die 10 by using the ordinary press machine in the second step has been described above.
It is also possible to use means for holding 4, 25 in a fixed position so that the upper and lower punches 8, 9 are brought closer together.

[0020]

As described above, according to the present invention, since the deep bead provided at the center is mainly molded in the first step, it is not necessary to move the rubber over the deep bead, and the damage of the rubber is prevented. . Then, in the second step, after filling the deep bead in the center with rubber, deep beads are formed on both sides while the die pieces are brought close to each other,
Even in this step, the rubber does not move over the deep bead, so that the rubber is not subjected to shearing force and has an effect of preventing damage.

[Brief description of drawings]

1A and 1B show the process of the present invention, FIG.
Is the first step, and (c) is the second step.

FIG. 2 is a sectional view of a processing device in a second step.

[Explanation of symbols]

 1a, 1b, 1c Work 2 First die 7 Rubber punch 10 Second die 2a, 2b, 2c, 10a, 10b, 10c Forming surface

Claims (1)

(57) [Claims] 1. A bulging method for a beaded pipe, which has a bead forming surface on its inner peripheral surface, inserts a tubular work into a die separable by a diameter line, and applies a bead by applying an internal pressure to the tubular work, A first step of bulging with a first die having a deep bead forming surface in the center and a pair of shallow bead forming surfaces on both sides thereof and a rubber punch, and adjacent beads having a deep bead forming surface in the center and both sides. A second step of bulging by pressing a rubber punch while bringing each die piece close to each other, using a second die having a die piece divided between molding surfaces and in the middle of each bead forming surface A method for bulging a beaded pipe, which comprises: