JP2505512B2 - Electromagnetic force press working method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an article by pressing a plate material.

(Prior Art) Press working of plate materials (in the present invention, press working is a general term for deep drawing, overhanging, ironing, hole expanding, etc.) equipment generally includes a die, a punch and It is composed of a granule holder. In the present invention, the articles collectively refer to products formed by pressing a plate material. A vessel with a shallow bottom or a shape that is not complicated can be molded by a single-step press process, but a deeper vessel or a vessel with a special shape has 2
Steps, steps of 3 or more times are performed.
Further, there is also a method of forming a deep container by performing reverse bulging using a rigid punch and then pressing.

Further, as a special pressing method, there is an opposed hydraulic forming method in which a hydraulic chamber acts as a die, and this method can reduce the number of processing steps.

The electromagnetic forming method is one of the high-energy speed machining methods, and has been mainly used for the pipe machining in the circumferential direction such as pipe expansion or caulking. An electromagnetic forming method has been proposed in which a plate material is processed by using one of a male mold and a female mold and a plane coil, but it is not possible to mold a deep bottomed article obtained by press working.

(Problems to be solved by the invention) For example, in order to form a deep container from a deep drawing or a plate material, there are two steps, three steps or more in a normal press work or a press work in which a pre-deformation by reverse bulging is performed. It is common to carry out processing a number of times. However, multi-stage deep drawing requires more time and die cost than single-stage processing, and is not economical.

On the other hand, the counter-hydraulic molding is a very excellent processing method because it is possible to form a deeper container from a plate material, and the die cost is low.

However, the counter-hydraulic molding method has a slower processing speed than that of general press processing, and thus the productivity is poor, and a large pressing force and a special pressing device are required to apply the counter-hydraulic pressure. In addition, since high-viscosity oil is used in the hydraulic chamber, there is a problem in economic efficiency and productivity such that the cost of cleaning the equipment in the post process becomes high.

The present inventors conducted a study with the intention of reducing the number of times of forming processing of a plate material by using an electromagnetic forming method as an auxiliary.
The outline of the electromagnetic forming method is described in "Plasticity and Machining" Vol. 11, No. 11
No. 9 (1970-12), pages 888-892 and "Metal Press," February 1983, pages 41-47, for an overview.

(Means for Solving the Problems) The first aspect of the present invention is to process a work blank plate by an electromagnetic coil incorporated in a press machine during the press working before the load applied by the punch to the work blank plate becomes maximum. It is intended to obtain a forming limit higher than the forming limit in the conventional deep drawing by adding an electromagnetic force to the.

In the present invention, by incorporating an electromagnetic coil in the press working apparatus, it is possible to apply an electromagnetic force to the work blank at an arbitrary timing. Further, although the press machine incorporating the electromagnetic coil is usually a die, the electromagnetic coil can be incorporated in the punch. In the present invention,
The timing of applying the electromagnetic force is (a) in the middle of press working, and (b) before the time when the load applied by the punch to the blank is maximized. (A) means that any timing may be used during press working. That is, when the press working is in progress, the working base plate is narrowed down at least slightly, and the electromagnetic force is applied. Since the working base plate is wrapped around the punch, (a) is a timing requirement.

Even if the press working is interrupted and the punch movement is stopped at the moment when the electromagnetic force is applied, the work plate will wind around the punch, but since the working efficiency will decrease, it will be used as an auxiliary force for working while continuing the press working. It is preferable to utilize electromagnetic force.

Further, at the time when the punch load becomes maximum, it breaks beyond the forming limit and there is no effect of electromagnetic force application, so (b) is a timing requirement.

The number of electromagnetic coils is usually one, but it may be two or more. When using two or more electromagnetic coils, the electromagnetic force generation timing of each coil may be shifted, and one coil may be arranged in the die and another coil may be arranged in the punch.

The second aspect of the present invention is to perform a conventional deep drawing process by performing pre-deformation on a workpiece plate by an electromagnetic coil incorporated in the press device and then performing press work in the same press device in a direction opposite to the pre-deformation. It is intended to obtain a molding limit higher than the molding limit of. In the present invention, a coil for applying an electromagnetic force is incorporated in the press working apparatus, and the base plate is reversely stretched and predeformed by the electromagnetic force immediately before starting the press working. Since the reverse bulging by the electromagnetic force is deformed at a higher speed than the reverse bulging by the rigid punch, the degree of work hardening is large and the effect of the reverse bulging is great.

It is also possible to separately press the machined blank pre-deformed by the electromagnetic force without incorporating the electromagnetic coil in the press machine. However, this method requires extra time, such as setup time, and results in poor productivity. Therefore, it was decided to perform pre-deformation and press working with the same press working apparatus.

The third aspect of the present invention is to perform pre-deformation by the second method,
Then, the first method is carried out when press working is carried out in the same press machine to further improve the molding limit.

Hereinafter, a specific example of the press working apparatus when the first method of the present invention is applied to deep drawing will be described with reference to FIG.

In FIG. 1, 1 is a blank, 2 is a punch, 3 is a blank holder, and 10 is a die incorporating an electromagnetic coil 5 for applying an electromagnetic force. The die 10 has a structure in which an electromagnetic coil-incorporating die 4 "is inserted between the normal dice 4 and 4 '. A non-conductive material is used for the die 4" in which the electromagnetic coil 5 is incorporated, or It is necessary to sufficiently consider the electrical insulating property with respect to the workpiece blank 1 and the dies 4, 4'by taking measures such as embedding the electromagnetic structure 5 in a resin which is a non-conductive material. The electromagnetic coil may be exposed in the cavity 6 as long as it is electrically insulated from the work sheet 1. As the structure of the die 10 incorporating the electromagnetic coil 5, a magnetic flux concentrator may be commonly used in the die so as to concentrate the magnetic flux near the punch shoulder in the cavity 6. In this common use, by combining magnetic flux concentrators of different sizes and electromagnetic coils, it is possible to mold several sizes with one electromagnetic coil. Second
The figure shows the magnetic force generating electric circuit. When the switch 11 is closed and the current from the power source 9 is stored in the condenser 8, then when the punch is pushed up to the state shown in FIG. By closing 7, the magnetic coil 5 is instantaneously supplied. As a result, the force generated by the sudden change in the magnetic field generated in the current coil 5 is applied to the machined blank. The processed blank plate 1 which is subjected to the action of the magnetic force is further squeezed by the punch 2 and processed to the final shape. Processed blank 1
As the material, a good conductive material such as aluminum, iron or copper is preferable, but a non-conductive material such as aluminum, iron or copper can be used as a driver for processing.

FIG. 4 is a drawing showing a specific example of a press working apparatus when the second method of the present invention is applied to deep drawing.

Inside the die cavity 6 of a normal deep drawing apparatus composed of the die 4, the punch 2 and the blank holder 3, there is provided a coil housing 7 capable of advancing and retracting in the axial direction, and the coil 5 therein is made of, for example, resin or the like. Embed and place. An electric circuit for instantaneously passing a current through the coil is as shown in FIG.

The coil housing 7 descends to the lowest end before the start of processing,
The base plate 1 is pre-deformed in a contact or non-contact manner with the base plate 1 and then rises. At the same time as this rise, the punch 2 rises to perform press working.

(Operation) The method according to the present invention is an electromagnetic force-added press working method that combines conventional press working and electromagnetic forming. Conventionally, the electromagnetic forming method proposed for forming a plate material has been a method of using a coil wound in a flat plate shape. However, in the first aspect of the present invention, a contracted tube conventionally used for compression forming of a tube. By applying the electromagnetic force for as an auxiliary force in the middle of the press working of the plate material, a limit higher than the forming limit in the conventional press working is obtained.

For example, in the drawing process, a blank plate 1 as a material to be processed
As shown by the arrow, the force applied to (Fig. 3) is the force applied to the blank plate from the punch 2 and pulls up the blank plate 1. The premise of this force is the portion indicated by the diagonal lines. Is a friction holding force that acts between the blank 1 and the punch 2.

This friction holding force is increased by applying a force to firmly wind the material around the cylindrical portion of the punch 2 by the electromagnetic force acting in the radial direction of the electromagnetic coil.
Push up to enable deeper drawing. As a result, the friction holding effect at the punch head, which is a fracture risk area in deep drawing, is increased, and the forming limit is improved. The most preferable drawing method is that a microscopically formed gap is formed between the punch 2 and the base plate 1 by minute unevenness, and even if the punch 2 is pushed up in this state, the gap is not reduced. A force is generated to bring the punch 2 and the base plate 1 into close contact with each other, and the contact area between them is increased.
Is a method of pushing up.

In the second aspect of the present invention, the shape of the blank changes as shown in FIGS. 5 (a) to (b) due to the reverse tension pre-deformation by the electromagnetic force applied immediately before the start of press working.
Also, this pre-deformation causes some Planck contraction (arrow). These bulging deformation and Planck's contraction occur in a very short time of several hundreds of microseconds, and are accompanied by remarkable work hardening. Due to these effects, machining with a high drawing ratio, which was impossible with the conventional single-stage deep drawing, is possible in FIGS.
It becomes possible in the process of (e).

(Example) Example 1 A blank of an aluminum alloy (JIS A1100-P) having a plate thickness of 0.8 mm was deep-drawn under the following conditions.

Condition (A) -Example of conventional method Punch: Diameter = 500 mm R radius: 5 mm Die: Diameter = 52.08 mm R radius: 5 mm Blank holder pressure: 200 kgf Lubricating oil: Water-soluble press working oil (trade name: Johnson Wax # 700 aqueous solution) Condition (B) -Example of the present invention The same deep drawing condition as the condition (A), except that an electromagnetic force generating circuit having the following rating was added as shown in FIG.

Capacitor capacity: 100μF Capacitor voltage: 8KV Electromagnetic coil: Inner diameter 100mmφ Cylindrical coil Flux concentrator: Inner diameter 50mmφ High permeability magnetic material ring Also, the full capacity of the condenser was discharged before the maximum load of punch stroke to apply electromagnetic force. . Discharge time is 10
It was 0 to 200 μsec.

 The results of drawing are shown in Table 1.

The drawing time was 2 to 3 seconds for the conventional method and the method of the present invention.

The limit drawing ratio (LD
R) is 2.05, but the LDR is improved to 2.20 in the electromagnetic force added deep drawing process according to the present invention.

Example 2 An aluminum alloy (JIS A1100-P) plate having a thickness of 0.8 mm was deep-drawn under the following conditions. For the shape of the punch head, a frustoconical punch, which is generally difficult to process, was used. The shape and dimensions of the punch head are shown in FIG.

Condition (A) -Example of conventional method Punch (taper punch): Diameter = 50 mm Die: Diameter = 52.08 mm R radius: 5 mm Blank holder pressure: 200 kgf Lubricating oil: Water-soluble press working oil (trade name: Johnson Wax # 700 aqueous solution) ) Condition (B) -Example of the present invention The same deep drawing condition as the condition (A), but an electromagnetic force generating circuit having the following ratings was added as shown in FIG.

Capacitor capacity: 100μF Capacitor voltage: 8KV Electromagnetic coil: 50mm, 10 turns, 1.7μH Molding results are shown in Table 2.

The drawing time was 2 to 3 seconds for the conventional method and the method of the present invention.

The limit drawing ratio (LD
R) is 1.40, but the LDR is improved to 2.15 in the electromagnetic force added deep drawing process according to the present invention.

(Effects of the Invention) Since the present invention is configured as the electromagnetic force applying press working method as described above, the following effects can be obtained.

The processing speed is the same as that of general press processing, and the productivity is better than that of opposed hydraulic molding.

Since the electromagnetic force acts for a short time and the electromagnetic force acts during the press working, there is almost no decrease in efficiency due to the addition of the electromagnetic force.

With regard to the limiting drawing ratio, even with the use of general press lubricating oil, a marked improvement can be seen.

Regarding the treatment in the post-process, since it is possible to use ordinary press oil, it is easy to wash the articles in the post-process.

Regarding the moldability of the container, if the method of the present invention is applied to the molding of the container, which has conventionally required the press processing of two or more steps or the special molding method such as the counter hydraulic pressure, the press processing of one step is sufficient. Therefore, productivity and economic efficiency are improved in terms of processing time and die cost.

Further, if the method of the present invention is applied to an article that has been conventionally formed by one-step pressing, it is expected that the thickness of the article can be reduced and the article can be made lighter.

[Brief description of drawings]

FIG. 1 is a sectional view of a press device for explaining a specific example in which the first method of the present invention is applied to deep drawing, FIG. 2 is a circuit diagram of an electromagnetic force generator, and FIG. 3 is a friction holding effect. Explanatory drawing, FIG. 4 is sectional drawing of the press apparatus for demonstrating the specific example which applied the 2nd method of this invention to deep drawing, FIGS. 5 (a)-(e) are 2nd of this invention. FIG. 6 is a diagram for explaining the deformation of the blank by the method of FIG. 6, and FIG. 6 is a diagram of the taper punch used in the second embodiment. 1 ... Base plate, 2 ... Punch, 3 ... Blank holder,
4 ... Die, 5 ... Electromagnetic coil, 6 ... Cavity, 7 ... Movable coil housing, 10 ... Dice

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Akira Hashimoto “Press drawing” (April 10, 1936) Nikkan Kogyo Shimbun pp. 89-96 "Pressing Handbook" edited by Japan Society for Plastic Processing (October 25, 1975) Maruzen p.p. 517-519

Claims (3)

(57) [Claims] Claim: What is claimed is: 1. An electromagnetic coil characterized in that an electromagnetic force is applied to a work blank plate by an electromagnetic coil incorporated in a press machine during a press working before the load applied to the work blank plate by a punch becomes maximum. Forced press working method. 2. An electromagnetic coil incorporated in the press machine is used to perform pre-deformation on a portion of the machined blank that comes into contact with the punch head in the next press work, and then pre-deform it with the same press machine. An electromagnetic force-applied pressing method characterized by performing pressing in the opposite direction. 3. A punch is added to the work plate when the work plate is pre-deformed by an electromagnetic coil incorporated in the press device and then pressed in the direction opposite to the pre-deformation by the same press device. An electromagnetic force-added press working method characterized in that an electromagnetic force is applied to a work blank by another electromagnetic coil during the press working before the load becomes maximum.