JPH0623442A - Multi-stage electromagnetic plastic working method for hollow material - Google Patents

Abstract

PURPOSE:To easily form a hollow material having different cross-sectional shapes in the axial direction or asymmetrical cross-sectional shapes to the axial direction by applying multi-stage electromagnetic power on specific parts of the hollow material. CONSTITUTION:When a pulselike strong magnetic flux is generated by flowing a large current in a magnetic coil 12, an inductive current flows in the surface layer of outer circumferential part of the hollow material 14 and the material 14 is formed by receiving a shrinking plastic deformation in the radial di-rection by a repulsive interaction between the inductive current and the current in the magnetic coil 12. The thicker a part of magnetic flux concentrators (13a, 13b and 13c) is, the stronger the repulsion becomes, accordingly, the amount of deformation becomes more in compliance with thickness of the concentrator part when the part becomes thicker. Thus, the hollow material 14 is applied with deformation whose amount is correspondin9 to projecting part of the magnetic flux concentrator in each stage and finally formed to a final shape having different cross-sectional shapes in the axial direction and much amount plastic deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage electromagnetic plastic working method for hollow materials for producing various parts having irregular cross sections, such as automobile parts, industrial equipment parts and transportation equipment parts, from hollow materials such as aluminum alloys. It is a thing.

[0002]

2. Description of the Related Art As a method for producing hollow parts having irregular cross-sections, hollow materials conventionally obtained by extrusion processing, etc. are subjected to secondary processing such as pipe expansion by a mandrel or contraction tube by roll processing, or solid materials. The method of cutting from the material is used.

[0003]

However, although a hollow part having a simple shape can be manufactured by the above-mentioned method, a complicated shape, for example, one having a different sectional shape in the axial direction or an asymmetrical section with respect to the axial line is formed. There is a problem in that those having a shape are extremely difficult to process.

The present invention is intended to solve the above-mentioned problems and to provide a multi-stage electromagnetic plastic working method of a hollow material capable of producing a hollow part having a complicated shape.

[0005]

In order to achieve the above-mentioned object, the multistage electromagnetic plastic working method for a hollow material according to the present invention achieves the above object by applying a multistage electromagnetic force to a predetermined portion of the hollow material (14). It is characterized in that it is molded and processed by being applied to.

The electromagnetic force is applied to the hollow member (14) by
For example, the hollow material (14) is inserted inside the electromagnetic coil (12) or the electromagnetic coils (16a, 16) are inserted inside the hollow material (14).
b) is inserted and this electromagnetic coil (12, 16a,
16b) by instantaneously flowing a large current to generate a pulsed strong magnetic field.

In the above-mentioned case, the distribution of the intensity of the electromagnetic force applied to the predetermined portion of the hollow member (14) is the winding density of the coil or the electromagnetic coils (12, 16a, 16).
b) adjustment of the distance between the hollow member (14) or addition of magnetic flux concentrators (13a, 13b, 13c), magnetic flux concentrator (1
3a, 13b, 13c) and the like.
The predetermined portion of the hollow material (14) in the present invention means
It does not matter whether the hollow material (14) is provided on the inner peripheral portion or the outer peripheral portion, or on the entire circumference of the hollow material (14).

[0008]

Function: For example, the hollow member (1
4) is inserted and an electromagnetic force is applied to the hollow material (14) by momentarily flowing a large current through the electromagnetic coil (12) to generate a pulsed strong magnetic field.
An induced current flows in the surface layer of the outer peripheral part of 4). A repulsive force acts between this induced current and the current flowing through the magnetic coil (12), and the hollow member (14) is plastically deformed so as to contract in the radial direction. When the electromagnetic coil (16a, 16b) is inserted inside the hollow material (14), the hollow material (14)
Induced current flows in the surface layer of the inner peripheral part of the hollow material (14)
Undergoes plastic deformation that expands in the radial direction.

The amount of plastic deformation of the hollow member (14) has a correlation with the strength of the electromagnetic force received at the deformed portion. Therefore, by applying an electromagnetic force having different strength and weakness distributions to a predetermined portion of the hollow member (14) in multiple stages, the hollow member (14) can have a complicated shape, for example, a member having a different cross-sectional shape in the axial direction or an axis line. It can be molded to have an asymmetrical cross-sectional shape. Further, by repeatedly applying electromagnetic force to the same portion in multiple stages, it is possible to increase the amount of plastic deformation as compared with the forming process in only one stage.

[0010]

EXAMPLES Two specific examples of the multistage plastic working method for hollow materials according to the present invention will be described with reference to the drawings.

(First Embodiment) In this embodiment, a method of applying an electromagnetic force from the outside of the hollow material to perform plastic working in the contracted tube direction in three steps will be described.

As shown in FIGS. 1 and 2, in the processing apparatus of the first, second and third stages of this embodiment, the large voltage instantaneously supplied from the DC high voltage power source (11). A total of three electromagnetic coils (12) that generate a pulsed strong magnetic field by an electric current are formed by being wound around a cylindrical magnetic flux concentrator (13a, 13b, 13c) that enhances the magnetic flux density, and each electromagnetic coil. (12) are arranged linearly. These magnetic flux concentrators (13a, 13b, 13
c) is a projection (15a,
15b, 15c). A hollow member (14) made of an aluminum alloy is loosely inserted inside the magnetic flux concentrator (13a, 13b, 13c). And
The hollow material (14) is sequentially conveyed to each stage, and is overlapped on the same portion and subjected to plastic working. A large current to the electromagnetic coil (12) is generated by closing the switch (23) and discharging the electric charge charged in the capacitor (22) from the DC high voltage power supply (11) through the resistor (21). It is supposed to be done. Further, in FIG. 2, the DC high-voltage power supply and its associated circuit are not shown.

In the processing apparatus having the above-mentioned structure, when a large current flows through the electromagnetic coil (12) and a pulsed strong magnetic field is generated, an induced current flows through the surface layer of the outer peripheral portion of the hollow material (14). , The induced current and the electromagnetic coil (1
The hollow material (14) is subjected to plastic deformation that contracts in the radial direction by the repulsive force acting between the hollow material (2) and the current flowing in (2), and is molded. At this time, the magnetic flux concentrators (13a, 13b, 1
The larger the thickness of 3c), the greater the repulsive force, and the greater the amount of plastic deformation. As a result, the hollow material (14) is removed from each magnetic flux concentrator (13a, 13b, 1) at each stage.
3c) a portion corresponding to the projecting portion (15a, 15b, 15c) is deformed in an amount corresponding to the shape, and the final shape having a large cross-sectional shape and a large plastic deformation amount is formed. .

In this embodiment, the magnetic flux concentrator (13
a, 13b, 13c) have uniform protrusions (15a,
15b, 15c) are provided, but the protrusion (15
a, 15b, 15c) or by changing the shape of the protrusions (15a, 15b, 15c) over the entire circumference, to process the hollow member (14) into an asymmetric cross-sectional shape with respect to the axis. Can be done easily.

By the way, in the case of machining with a large amount of plastic deformation as in the present embodiment, in order to obtain the desired shape in one step of machining, the protrusion (15a) of the magnetic flux concentrator (13a) should be raised. It will be good, but at the start of processing, a magnetic flux concentrator (1
Since the inner diameter of 3a) must be larger than the outer diameter of the hollow member (14), the magnetic flux concentrator (13a) and the electromagnetic coil (12) inevitably become large. Further, even if these are enlarged, the distance between the magnetic flux concentrator (13a) and the processed portion of the hollow member (14) becomes large as the plastic deformation progresses, and the electromagnetic force acting on the hollow member (14) weakens. Therefore, in order to continue the plastic deformation of the hollow material (14), a larger electromagnetic force is required than in the initial stage of processing, and the power source and its associated circuit must be upsized. Such an increase in the size of the processing apparatus still increases the manufacturing cost even considering that a plurality of processing apparatuses are required to carry out the present invention. Therefore, the present invention in which processing is performed in multiple stages is advantageous not only in complicated processing but also in manufacturing cost of a product having a large amount of deformation.

(Second Embodiment) In this embodiment, a method of applying an electromagnetic force from the inside of the hollow material to perform plastic working in the tube expanding direction in two steps will be described.

As shown in FIG. 3, in the processing apparatus of the first stage of this embodiment, the diameter gradually increases from the one end to the other end in a conical shape, and from the one end side. An electromagnetic coil (16a) that is gradually and densely wound on the other end side is loosely inserted inside the hollow member (14). Further, in the processing device of the second stage, the diameter of the electromagnetic coil (16b) gradually increases from the one end side to the other end side in the shape of a cone, and is larger than that of the electromagnetic coil (16b) of the first stage. ) Is loosely inserted inside the hollow member (14). And hollow material (1
4) is conveyed from the first stage to the second stage, and plastic working is performed in two stages. In FIG. 3, a DC high-voltage power supply for instantaneously supplying a large current to the electromagnetic coils (16a, 16b) and its associated circuit are not shown.

In the processing apparatus having the above-described structure, when a large current flows through the electromagnetic coils (16a, 16b) to generate a pulsed strong magnetic field, an induced current is generated in the surface layer on the inner peripheral portion of the hollow material (14). Flow, and the hollow member (14) undergoes plastic deformation that expands in the radial direction by the repulsive force acting between this induced current and the current flowing through the electromagnetic coils (16a, 16b), and is formed. At this time, the smaller the distance between the electromagnetic coil (16a, 16b) and the inner peripheral surface of the hollow member (14), the more the electromagnetic coil (16a, 16b).
The closer the b) is wound, the more repulsive force the hollow material (1
The large amount of plastic deformation also increases the amount of plastic deformation. As a result, the hollow material (14) is shaped like a cone and has a greater gradient in two steps. In this way, even if the diameter of the electromagnetic coil (16a, 16b) that can be inserted into the hollow member (14) is limited and the desired shape cannot be obtained by one-step processing, there are two or more steps. The amount of plastic deformation can be increased by processing with. Further, a processed product having a complicated shape that is difficult to process in one step can be manufactured by processing in multiple steps.

In this embodiment, the hollow material (1
Although only the electromagnetic coils (16a, 16b) are inserted and installed in the inside of 4), the electromagnetic coils (16a, 16b) can be easily inserted into the hollow member (14) while maintaining the shape of the electromagnetic coils (16a, 16b). ) May be formed by winding a wire around a conical support shaft having a predetermined shape.

In each of the above-mentioned embodiments, all the processing steps are formed by the electromagnetic force only. However, a die may be used together in the final processing step. For example, as shown in FIG. 4, if a die (18) is arranged outside the hollow member (14) in which the electromagnetic coil (17) is loosely inserted, the hollow member (14) expanded by electromagnetic force. It is possible to regulate the amount of plastic deformation of, and to make the processed product with a shape following the die (18) with high dimensional accuracy. Also, the dice (18)
Combined use also facilitates molding of complex shapes. In addition,
In FIG. 4, reference numeral (19) indicates a support shaft for maintaining the shape retention of the electromagnetic coil (17).

The above-mentioned plastic working can be carried out both cold and hot. However, since the electromagnetic force to be applied is small and the corner working device can be simplified, the plastic deformation of the hollow material is possible. It is preferable to carry out the heat while rich in nature.

Further, after the hollow material is extruded, the molding energy of the present invention is applied at the end of the stretch treatment, whereby the processing energy can be reduced.

[0023]

According to the present invention, since the hollow material is molded by applying electromagnetic force in multiple stages, for example, by changing the strength and weakness distribution of the electromagnetic force, the axial direction of the conventional hollow material can be changed. In addition to uniform expansion and contraction, it is possible to easily form hollow materials having a different cross-sectional shape in the axial direction and a hollow material having a cross-sectional shape asymmetric with respect to the axial line. Further, since the plastic working method of the present invention is performed in a non-contact manner by an electromagnetic force, there is no risk of deterioration of the quality of the processed product due to heat generation caused by friction with the tool, mechanical shock, or the like.

[Brief description of drawings]

FIG. 1 is a schematic view showing one of three electromagnetic coils in a processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a processing apparatus and a processing process at each stage in the first embodiment of the present invention.

FIG. 3 is a longitudinal cross-sectional view of a main part of a processing device and a processing process at each stage in the second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a main part showing a modified example of the embodiment of the present invention.

[Explanation of symbols]

 12, 16a, 16b ... Electromagnetic coil 13a, 13b, 13c ... Magnetic flux concentrator 14 ... Hollow material 15a, 15b, 15c ... Protrusion

Claims (1)

[Claims] 1. A hollow material (14) is provided with the hollow material (14).
A multi-stage electromagnetic plastic working method for a hollow material, characterized by performing a forming process by applying an electromagnetic force to a predetermined portion of the hollow member in multiple stages.