JPH0824969A - Electromagnetic forming device for tube expansion and manufacture of tube-like formed product - Google Patents

Abstract

PURPOSE:To put a method, for forming a metal tube made after the inner shape of a metallic mold by expanding the diameter of the metal tube with Lorentz's force, to a practical use. CONSTITUTION:The metal tube K is incorporated in a metallic mold 1, and a coil 2 wound in the peripheral direction of the metal tube K is incorporated in the inner part of the metal tube K, and magnetic field Ba is formed at the outer part of the metal tube K along the axial direction of the metal tube K. A large amt. of current is allowed to flow momentarily to the coil 2 under the condition above to cause excitation and the current Ic is induced in the peripheral direction of the metal tube K by this excitation. The diameter of the metal tube K is expanded by the Lorentz's force resulting from the induction current Ic and the magnetic field Ba and is brought into press contact with the inner surface of the metallic mold 1 to form the metal tube K after the inner surface shape of the metallic mold 1. By this method, the metal tube product formed after the inner surface shape of the metallic mold can suitably be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic molding device for expanding a pipe and a method for manufacturing a tubular molded product. More specifically, the diameter of the molded pipe is expanded by Lorentz force to mold the molded pipe into the inner surface of the mold. The present invention relates to a method for producing a tubular molded product capable of suitably producing a tubular molded product which is molded according to the electromagnetic expander for pipe expansion and the inner surface shape of the mold.

[0002]

2. Description of the Related Art Conventionally, an electromagnetic molding device 500 for a contracted tube as shown in FIG. 5 is known. This electromagnetic forming machine for contracted tubes 500
Is a mold 501 to be inserted into the metal tube K and the metal tube K.
And a coil 502 wound in the circumferential direction of the metal tube K, and a power source (not shown) for supplying power to the coil 502. When a large current is instantaneously applied to the coil 502 from the power source for excitation, a strong magnetic field Bb is formed inside the coil 502. Further, the current Ic is induced in the circumferential direction of the metal tube K. Then, a strong Lorentz force acts between the magnetic field Bb and the induced current Ic, the diameter of the metal tube K is reduced, and the metal tube K is pressed against the outer surface of the die 501. As a result, the metal pipe K is fitted to the outer surface shape of the die 501.
Can be molded.

[0003]

In contrast to the electromagnetic compactor 500 for contracting pipes, the electromagnetic compactor 6 for expanding pipes as shown in FIG. 6 is used.
00 can be considered. This electromagnetic expander 600 for pipe expansion has a mold 601 for accommodating a metal tube K therein, a coil 602 accommodated inside the metal tube K and wound in the circumferential direction of the metal tube K, and the coil 602. And a power supply (not shown) for supplying power to the device. The coil 6 from the power source
When a large current is instantaneously applied to 02 to be excited, the coil 60
A magnetic field Bb is formed outside of 2. Further, the current Ic is induced in the circumferential direction of the metal tube K. Then, the Lorentz force acts between the magnetic field Bb and the induced current Ic, and the metal tube K
Is expanded and pressure-bonded to the inner surface of the mold 601. As a result,
The metal tube K should be able to be molded according to the inner surface shape of the mold 601.

However, in reality, the electromagnetic expanding device 600 for expanding a pipe has a problem in that the metal pipe K cannot be formed in conformity with the shape of the inner surface of the die 601. The reason is that, outside the coil 602, the magnetic field Bb weakens rapidly as the distance from the coil 602 increases, so if the diameter of the metal tube K increases even a little, the Lorentz force sharply weakens and the pressure is applied to the inner surface of the die 601. This is because the metal tube K cannot be expanded in diameter. For this reason, the electromagnetic forming machine 500 for pipe shrinking shown in FIG. 5 has been put to practical use, but the electromagnetic forming machine 600 for pipe expansion shown in FIG. 6 has not been put to practical use.

Therefore, a first object of the present invention is to expand the diameter of the metal tube by Lorentz force to form a metal tube in conformity with the shape of the inner surface of the mold. To provide. A second object of the present invention is to provide a method for manufacturing a tubular molded product, which can suitably manufacture a tubular molded product molded according to the shape of the inner surface of a mold.

[0006]

According to a first aspect of the present invention, a mold (1) for accommodating a pipe to be molded (K) therein, and a pipe (K) accommodated inside the pipe to be molded (K) are provided. Formed tube (K)
And a magnetic field forming means (3) for forming a magnetic field (Ba) outside the molded pipe (K) along the axial direction of the molded pipe (K). 3 ', 31)
And power supply means (4, 5, 5) for supplying power to the coil (2).
6 and 7), a large current is momentarily applied to the coil (2) to excite the coil (2), and the molded tube (K) is excited by this excitation.
A current (Ic) is induced in the circumferential direction of the
c) and the magnetic field (Ba), the diameter of the pipe to be molded (K) is expanded by the Lorentz force and pressed onto the inner surface of the mold (1), and the pipe to be molded (K) is fitted to the inner surface shape of the mold (1). (1) is provided, and an electromagnetic molding device (100) for pipe expansion is provided.

According to a second aspect, the present invention relates to a mold (1) for accommodating a molded pipe (K) inside, and a molded pipe (K) housed inside the molded pipe (K). A coil (2) wound in the circumferential direction and permanent magnets (21, 22, 22) that form a magnetic field (Ba) outside the molded tube (K) along the axial direction of the molded tube (K). 22 ') and power supply means (4, 5, 6, 7) for supplying power to the coil (2), and a large current is momentarily applied to the coil (2) to excite the coil (2). A current (Ic) is induced in the circumferential direction of the molded pipe (K), and the Lorentz force between the induced current (Ic) and the magnetic field (Ba) expands the molded pipe (K) to form a mold (1 ), The pipe forming electromagnetic molding machine (200) is characterized in that the pipe to be molded (K) is molded according to the inner surface shape of the mold (1). provide.

According to a third aspect of the present invention, in the present invention, the molded pipe (K) is housed inside the mold (1), and the molded pipe (K) is circumferentially arranged inside the molded pipe (K). The coil (2) wound around the coil (2) is housed, and a magnetic field (Ba) is formed outside the molded tube (K) along the axial direction of the molded tube (K). A large current is instantaneously applied to 2) for excitation, and a current (Ic) is induced in the circumferential direction of the molded pipe (K) by this excitation, and the induced current (Ic) and the magnetic field (Ba) are combined. A tube characterized in that the pipe to be molded (K) is expanded in diameter by Lorentz force and pressure-bonded to the inner surface of the mold (1), and the pipe to be molded (K) is molded according to the shape of the inner surface of the mold (1). A method for manufacturing a molded article is provided.

[0009]

According to the first aspect, the electromagnetic forming device for pipe expansion (10
In 0), the magnetic field forming means (3, 3 ′) for forming the magnetic field (Ba) along the axial direction of the molded pipe (K) was provided outside the molded pipe (K). Therefore, a strong magnetic field (Ba) is formed even outside the coil (2) to some extent from the coil (2). As a result, a strong Lorentz force is maintained even when the pipe to be molded (K) is expanded in diameter, and the mold (1)
The diameter of the pipe to be molded (K) can be expanded to such an extent that it can be crimped to the inner surface of the. Therefore, the pipe (K) to be molded can be molded according to the inner surface shape of the mold (1).

In the pipe expanding electromagnetic molding device (200) according to the second aspect, a permanent magnet (Ba) is formed outside the molded pipe (K) to form a magnetic field (Ba) along the axial direction of the molded pipe (K). 21, 22, 22 ') are provided. Therefore, a strong magnetic field (Ba) is formed even outside the coil (2) to some extent from the coil (2). As a result, a strong Lorentz force is maintained even if the diameter of the pipe to be molded (K) is expanded, and the diameter of the pipe to be molded (K) can be expanded to such an extent that it is pressed against the inner surface of the mold (1). . Therefore, the pipe (K) to be molded can be molded according to the inner surface shape of the mold (1). Furthermore, since the permanent magnets (21, 22, 22 ') are used, low power consumption can be achieved.

In the method for producing a tubular molded article according to the third aspect, the tubular molded article molded in conformity with the inner surface shape of the mold can be suitably produced by the above-mentioned action.

[0012]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. The present invention is not limited to this.

First Embodiment FIG. 1 is a block diagram showing an electromagnetic molding device for pipe expansion according to a first embodiment of the present invention. This electromagnetic expanding device 100 for expanding a pipe is made of a steel mold 1 for containing a metal pipe K of soft iron, copper, aluminum or the like, and a metal pipe K housed inside the metal pipe K and wound in the circumferential direction of the metal pipe K. The turned coil 2, the Helmholtz coils 3 and 3 ′ that form a magnetic field Ba along the axial direction of the metal tube K, and a power supply device (4 that supplies power to the coil 2
5, 6, 7), a DC power supply 31 for feeding the Helmholtz coils 3, 3 ', and the power supply device (4,5, 6, 6).
7) and the control unit 10 for controlling the DC power supply 31. The power supply device (4,5, 6, 7) includes a DC high voltage power supply 4, a charging switch 5, and a capacitor 6.
And a discharge switch 7.

FIG. 2 shows the Helmholtz coils 3, 3 '.
Current Ia flowing in the coil 2 and current Ib flowing in the coil 2
Is a time chart of. First, the DC power source 31 supplies the current Ia to the Helmholtz coils 3 and 3 '. Current I
a has a maximum value after a rise time (for example, 2 to 3 ms), and the strength of the magnetic field Ba formed also has a maximum value (for example, 10,000 to 50,000 gauss). Here, the charge switch 5 is turned off and the discharge switch 7 is turned on for a short time (for example, 100 μs).
Then, the capacitor 6 instantaneously supplies a large current Ib (for example, 100 kA) from the capacitor 6 to the coil 2. Then
A magnetic field Bb is instantaneously formed by the current Ib, and
A large current Ic is induced in the metal tube K in a direction to cancel it. Thereby, the magnetic field Ba and the induced current Ic
The strong Lorentz force acts between the two, and the diameter of the metal tube K is expanded. The magnetic field Ba is applied to the Helmholtz coils 3, 3 ′.
Therefore, even if the diameter of the metal pipe K is expanded,
There is no weakening. Therefore, the strong Lorentz force continues to work, and the diameter of the metal tube K is expanded until it is pressed against the inner surface of the mold 1. That is, the metal tube K is formed in conformity with the inner surface shape of the mold 1.

Next, as shown in FIG. 3, the discharge switch 7
Is turned off and the charging switch 5 is turned on to charge the capacitor 6 from the DC high voltage power source 4 to prepare for the next molding. In addition, from the DC power supply 31 to the Helmholtz coil 3,
The supply of the current Ia to 3'is stopped.

According to the above electromagnetic expander 100 for pipe expansion,
The metal tube K can be put into practical use by expanding the diameter of the metal tube K by the Lorentz force and press-bonding the metal tube K to the inner surface of the mold 1 so as to match the inner surface shape of the mold 1. That is, it becomes possible to suitably manufacture a metal tube molded product that is molded according to the inner surface shape of the mold 1.

-Second Embodiment- FIG. 4 is a block diagram showing an electromagnetic molding device for pipe expansion according to a second embodiment of the present invention. This electromagnetic expander 200 for pipe expansion has a first
Instead of the Helmholtz coils 3, 3 ′ and the DC power supply 31 in the electromagnetic expanding device 100 for expanding a pipe of the embodiment, a metal pipe K is used.
Of the permanent magnet 21 and the ferromagnetic yokes 22, 2 so as to form the magnetic field Ba along the axial direction of the metal tube K outside the
2'is arranged. This electromagnetic expander 20 for pipe expansion
Even with 0, it becomes possible to practically expand the diameter of the metal tube K by Lorentz force, press-fit it to the inner surface of the mold 1, and mold the metal tube K according to the shape of the inner surface of the mold 1. That is, it becomes possible to suitably manufacture a metal tube molded product that is molded according to the inner surface shape of the mold 1. Since the permanent magnet 21 is used, there is no need of electric power for forming the magnetic field Ba, and there is an advantage that low power consumption can be achieved.

[0018]

According to the electromagnetic expander for pipe expansion of the present invention,
It becomes possible to practically expand the diameter of the pipe to be molded by Lorentz force and mold it according to the inner surface shape of the mold. Also,
According to the method for manufacturing a tubular molded product of the present invention, it is possible to preferably manufacture a tubular molded product molded according to the shape of the inner surface of the mold. Therefore, it is particularly useful for manufacturing air pipes of automobiles.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an electromagnetic molding device for pipe expansion according to a first embodiment of the present invention.

FIG. 2 is a time chart showing the timing of power supply in the pipe expanding electromagnetic molding device of FIG.

FIG. 3 is another configuration diagram showing the electromagnetic expander for pipe expansion of the first embodiment of the present invention.

FIG. 4 is a configuration diagram showing an electromagnetic molding device for pipe expansion according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional electromagnetic forming device for a contracted tube.

FIG. 6 is a configuration diagram showing an electromagnetic molding device for expanding a tube obtained by modifying the electromagnetic molding device for a contracted pipe of FIG. 5;

[Explanation of symbols]

 100,200 Electromagnetic forming device for tube expansion 1 Mold 2 Coil 3,3 'Helmholtz coil 31 DC power supply 4 DC high voltage power supply 5 Charge switch 6 Capacitor 7 Discharge switch 21 Permanent magnet 22, 22' Ferromagnetic yoke

Claims (3)

[Claims] 1. A mold (1) for accommodating a molded pipe (K) therein, and a coil housed in the molded pipe (K) and wound in the circumferential direction of the molded pipe (K). (2) and a magnetic field forming means (3) for forming a magnetic field (Ba) along the axial direction of the molded pipe (K) outside the molded pipe (K).
3 ', 31) and a power supply means (4,5, 6, 7) for supplying power to the coil (2), an electromagnetic forming machine (100) for pipe expansion. 2. A mold (1) containing a molded pipe (K) inside, and a coil housed inside the molded pipe (K) and wound in the circumferential direction of the molded pipe (K). (2) and permanent magnets (21, 2) that form a magnetic field (Ba) along the axial direction of the molded pipe (K) outside the molded pipe (K).
2, 22 ') and power supply means (4,5, 6, 7) for supplying power to the coil (2), the electromagnetic expander for pipe expansion (100). 3. A molded pipe (K) is housed inside a mold (1), and a coil (2) wound inside the molded pipe (K) in the circumferential direction of the molded pipe (K). ) Is accommodated, a magnetic field (Ba) is formed outside the molded pipe (K) along the axial direction of the molded pipe (K), and in that state, a large current is momentarily applied to the coil (2). To excite a current (Ic) in the circumferential direction of the pipe to be molded (K), and the Lorentz force between the induced current (Ic) and the magnetic field (Ba) causes the pipe to be formed ( A method for producing a tubular molded article, which comprises expanding the diameter of K) and crimping it on the inner surface of the mold (1), and molding the pipe to be molded (K) according to the inner surface shape of the mold (1).