JPH07223027A - Die and method magnetization press forming - Google Patents

Abstract

PURPOSE:To efficiently derive the formability of a metal sheet so as to improve the formability by supplying the specific electromagnetic force to the part in contact with a sheet to be worked. CONSTITUTION:The part is contact with a thin sheet to be worked 1 of a punch 2, or punch 2/die 3/blank holder plate 5 are made of a high magnetic metal having about 10-100 gauss magnetism, also, a magnetism of about 10-100 gauss is given to the material to be worked with placing a magnet in the inside of die, the magnetic metal sheet 1 is accustomed to a punch shape, the load applied on a vertical wall part is widely dispersed. By this method, different from an advanced technology of warm forming method and hydraulic counter pressure forming method, despite a special device and large scale die modification are not required, improvement of formability is achieved. Accordingly, this method is very effective for a deep drawing/bulging/compound forming die and a press forming method of the magnetic metal thin sheet 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press molding die and a press molding method for press molding a magnetic metal thin plate.

[0002]

2. Description of the Related Art In the processing of thin metal sheets for automobile parts and the like, a predetermined shape is given to the thin metal sheet by performing deep drawing forming, stretch forming and composite forming with a press machine. However, the formability of these thin metal plates depends on the shape of the mold, the conditions of lubrication / pressing, and the mechanical property values of the material, and the shape of the moldable part and the product height are limited by these factors. Therefore, in order to obtain a press-formed product with a predetermined forming depth, use a thin metal plate with high formability, use highly lubricating oil for press forming, or loosen the die shape to improve formability. Method is used.

However, a metal thin plate having a high formability is generally expensive and economically disadvantageous. Further, since the highly lubricating oil usually has a high viscosity, the working environment at the press site is significantly impaired.

Further, the method of changing the mold shape to a loose shape is limited because the design of the parts is changed, and it is necessary to combine it with other improving methods to obtain a predetermined shape.

On the other hand, as an improvement measure of the forming method, a counter-hydraulic forming method for increasing the forming height by forcibly pressing a thin metal plate against the punch to increase the frictional force with the punch (for example, Kazuhiko Nakamura, Profile, Vol.34, No.11,
(1993) P1-7) and a warm forming method for improving the forming ability of a thin metal plate by controlling the temperature and speed during forming have been devised. However, in these new molding methods, the molding machine and the mold are different from the conventional machines and molds, and therefore a large capital investment is required to introduce them newly.

An electromagnetic forming method is known as a special forming method (for example, Hideo Suzuki, Metal, Vol. 5).
6, No. 7 (1986) P56-62), different from forming by mechanical force with a punch and a die, in the electromagnetic forming method, a large current is passed through the coil at once to perform high-energy processing by a magnetic field, so a large-capacity capacitor or special type is generally used. Need different equipment.

As described above, in the conventional press forming technology for a thin metal plate, which is premised on mass production, it is impossible to fully utilize the forming performance of the thin metal plate, and a high-priced thin metal plate is purchased and processed. There was a need.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art by limiting the forming depth in the press forming of a metal thin plate without the need for a special device or die. An object of the present invention is to provide a method of more efficiently drawing out the forming ability of a metal thin plate and improving the formability by merely applying a magnetic or electromagnetic force to the portion of the mold that contacts the thin plate to be processed.

[0009]

Means for Solving the Problems In the press forming using a punch, a die, and a wrinkle holding plate, the present inventors have found that magnetic properties of steel plates, surface-treated steel plates, nickel plates, etc., and their alloys, surface-treated plates, etc. When pressing (deep drawing) a thin metal plate, a ferromagnetic metal having a magnetism of 10 to 100 gauss is arranged only in the punch, or in the part of the punch and the die / wrinkle holding plate that is in contact with the thin plate to be processed. And an electromagnet inside the die that composes the die and wrinkle holding plate,
It has been found that the press formability of a magnetic metal thin plate can be improved by using a magnetizing press die capable of supplying an electromagnetic field of 10 to 100 Gauss to a work material.

The present invention is constructed on the basis of this finding, and the gist thereof is (1) in a die for press-forming (deep drawing, overhanging, composite forming) a thin metal plate by a punch, a die and a pressing plate,
A magnetizing press molding die characterized in that a portion in contact with a thin plate to be processed is magnetized to 10 to 100 Gauss.

(2) The portion in contact with the thin plate to be processed is 10 to 1
The magnetizing press molding die according to the item (1), which is a ferromagnetic metal magnetized to 00 Gauss.

(3) Inside the portion contacting the thin plate to be processed,
The magnetizing press molding die according to (1) above, which has an electromagnet capable of magnetizing 10 to 100 Gauss on the surface.

(4) Using the magnetizing press molding die described in the above (1), (2) or (3), a magnetic metal thin plate having a plate thickness of 0.15 mm to 2.50 mm has a magnetic property of 10 to 100 Gauss. Press forming (deep drawing, overhanging,
A magnetizing press molding method characterized in that the composite molding is performed.

[0014]

The present invention will be described in detail below.

Usually, when deep drawing, overhang molding, and composite molding are performed by a press machine, a blank and pressing force necessary for suppressing wrinkles and controlling material inflow are applied to the flange portion of the workpiece by the die and the wrinkle pressing plate. . Whether or not a press-molded part can be molded has rupture due to a material flow failure, wrinkles due to insufficient wrinkle holding force, and defective shape, but the most common molding failure is rupture at the punch shoulder (α rupture). Is. In the case of deep drawing and composite molding, shrinkage flange deformation resistance (or stretch flange deformation resistance) and friction resistance of the flange part, bead resistance at the bead part and bending / bending back deformation at the die shoulder part. The resistance force is applied to the vertical wall portion of the work material as a forming load. In the case of overhang molding, the inflow of the flange is suppressed, so
The deformation resistance of the material in the die cavity is mainly applied to the vertical wall portion. When the breaking strength of the work material cannot bear the forming load, the above α break occurs.

Therefore, in order to improve the press formability of the work material, each component of the forming load is lowered, and the breaking strength of the portion that bears the forming load is improved, or the forming load applied to the vertical wall portion is further improved. Widely dispersed. The warm forming method already devised applies the principle of reducing the deformation resistance of the work material, and the counter-hydraulic forming method uses the principle of spreading the forming load applied to the vertical wall in a wider range. It is a technique. According to the present invention, the punch, or the portion of the punch, die, or wrinkle holding plate that contacts the thin plate to be processed is made of a ferromagnetic metal having a magnetism of about 10 to 100 gauss, or an electromagnet is arranged inside the die to be the object to be processed. By applying an electromagnetic field of 10 to 100 Gauss to the processed material,
This is a method of making it possible to spread the forming load applied to the vertical wall portion in a wider range by adapting the magnetic metal thin plate into a punch shape. (However, in the method of the present invention, since the magnetic force or electromagnetic force applied to the mold is extremely small, it is not possible to explain all the reasons why the moldability is improved only by the above-mentioned action, and the contribution of the magnetic force which has not yet been clarified. By the above action, unlike the warm molding method and the counter-hydraulic molding method of the prior art, it is possible to improve the moldability without requiring special equipment or major mold modification. .

FIG. 1 shows a general cross-sectional shape of the magnetizing press die of the present invention. 1 is a magnetic metal thin plate of a work material, 2 is 1
A punch made of a ferromagnetic metal having a magnetism of about 0 to 100 gauss, 3 is a normal die, or a die made of a ferromagnetic metal having a magnetism of about 10 to 100 gauss, 4 is an ordinary wrinkle holding plate or 10 1 shows a wrinkle holding plate made of a ferromagnetic metal having a magnetism of about 100 gauss. A general metal thin plate such as a steel plate, a nickel plate, or an alloy thereof can be applied to the magnetic metal thin plate. Although the simplest tool shape is shown in FIG. 1, the shape of the punch, the die, and the wrinkle holding plate is more complicated in a normal press die.

Next, the limiting conditions of the present invention will be described in detail.
The magnetism applied to the die on the surface in contact with the thin plate to be processed, particularly the punch, requires magnetism of 10 to 100 gauss or electromagnetism. That is, if it is less than 10 gauss, the suction between the thin plate to be processed and the punch die surface becomes insufficient, sufficient frictional force between the tool and the tool cannot be obtained, and the formability cannot be improved. On the other hand, when a magnetic force or electromagnetic field exceeding 100 Gauss is applied to the punch die, the moldability can be improved as well, but dust such as iron powder tends to be adsorbed on the tool surface, resulting in pimples, stars, etc. Molding defects due to product defects in

When a magnetic or electromagnetic field exceeding 100 Gauss is applied to the portion of the die and the wrinkle holding plate which is in contact with the thin plate to be processed, the resistance to the material inflow increases, so that the formability is improved under the same lubricating conditions. Does not lead to the improvement of. Furthermore, since foreign matter such as iron powder is likely to adhere to the die as with the punch tool, the die and the wrinkle holding plate are preferably 100 gausses or less.

Next, regarding the plate thickness, 0.15 mm
In the following, the force of adsorbing to the die is too strong, and the molding load of the work piece is excessively applied, resulting in breakage. In the case of a thin plate to be processed with a thickness of 2.50 mm or more,
With the magnetic force applied to the mold, which has already been specified, a sufficient suction force for the punch cannot be given, and only a slight improvement in moldability can be obtained. Therefore, the plate thickness applicable to the method of the present invention is
It is set to 0.15 mm or more and 2.50 mm or less.

The present invention based on the above-mentioned limiting conditions exerts a sufficient effect not only for a mold having a simple shape in the embodiment but also for a mold having a complicated shape. The patent claims include these.

[0022]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 shows a schematic view of a magnetizing press molding die according to an embodiment of the present invention.

The magnetic metal thin plate is a steel plate or a nickel plate,
Also, thin metal plates having magnetism such as alloys and plated plates thereof can be applied, of which the plate thickness is 0.12 mm
It carried out about 3.0 mm ultra-soft steel plate and a mild steel plate.

For conventional pressing dies (punch die and wrinkle press plate) generally used in the range of 10 to 120
Gaussian magnetism is added. As the thin plate material to be processed, blank diameters of φ140 mm to φ190 mm were prepared at 5 mm intervals, and press working was performed under the lubrication condition with rust preventive oil. As a comparative example of the conventional press working method, under the same working conditions, the punch, die, and wrinkle holding plate were completely demagnetized,
The punch, die, and wrinkle holding plate were subjected to the conditions of 120 Gauss.

The moldability was evaluated by using the value (LDR) obtained by dividing the maximum blank diameter that could be molded by the punch diameter while varying the wrinkle pressing pressure and the blank diameter.

The results are shown in Table 1. Table 1 examines the effect of the magnetizing press molding method when the magnetism applied to the mold tool is changed, and under the press molding conditions in which the magnet is given to the tool, the moldability is better than that when the magnetism is zero. You can see that Since the number of repetitions was 3 in the examples of Table 1, no terrible star eyes and pimples were found even under the condition of magnetic 120 gauss, and product defects were slight. However, in actual production, as the number of products increases, slight product flaws develop into serious flaws, so the magnetism applied to the mold is 1
It is preferably 00 gauss or less.

Further, the plate thickness of the work material is 0.12 mm
The effect of the magnetic press molding method was examined by changing to 3.0 mm. The results are shown in Table 2. From this result, when the plate thickness is 0.12 mm, the formability in the magnetic press molding method is poor,
It was found that the effect of the magnetic press molding method was almost eliminated when the plate thickness was 3.0 mm.

From this, the thickness of the work piece is 0.15 mm.
It can be said that about 2.50 mm is suitable.

[0030]

[Table 1]

Press conditions (φ80 mm cylindrical deep drawing) Press machine: 80 ton hydraulic press punch: φ78 mm-shoulder R5 mm Cylindrical punch die: φ80 mm-die shoulder R5 mm Plate thickness: 0.80 mm Blank diameter: φ140 mm to φ190 mm (5 mm) Interval) Moisture: As anti-rust oil is applied

[0032]

[Table 2]

Pressing condition (φ80 mm cylindrical deep drawing) Press machine: 80 ton hydraulic press punch: φ78 mm-shoulder R5 mm Cylindrical punch die: [plate thickness] ~ 0.80 mm → φ80 mm-die shoulder R5 mm ~ 2.30 mm → φ83 mm-Die shoulder R5 mm to 3.00 mm → φ85 mm-Die shoulder R5 mm Material: SPCC Blank diameter: φ90 mm to φ160 mm (5 mm interval) Lubrication: As applied with anti-rust oil

[0034]

INDUSTRIAL APPLICABILITY As described above, the method of the present invention is extremely effective as a die for deep drawing / overhanging / composite molding of a magnetic metal thin plate and a press molding method, and a special press machine or a major die modification is required. Since it is not necessary, it has high industrial value.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example magnetizing press die according to the present invention.

[Simple explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic metal thin plate 2 ... Punch die which has a magnetism of 10-100 gauss 3 ... Die die 4 ... A part of die die which has a magnetism of 10-100 gauss 5 ... Wrinkle holding plate 6 ... 10 Part of the wrinkle holding plate that holds 100 Gauss magnetism

Front Page Continuation (72) Inventor Matsuo Usuda 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technical Development Division

Claims (4)

[Claims] 1. A press forming (deep drawing, overhanging, composite forming) die for a metal thin plate using a punch, a die and a pressing plate, wherein a portion in contact with the thin plate to be processed is magnetized to 10 to 100 Gauss. Magnetizing press molding die. 2. A portion in contact with a thin plate to be processed is 10 to 100.
The magnetizing press molding die according to claim 1, which is a ferromagnetic metal magnetized to Gauss. 3. The magnetizing press molding die according to claim 1, wherein an electromagnet capable of magnetizing 10 to 100 Gauss on the surface is provided inside the portion in contact with the thin plate to be processed. 4. A plate thickness of 0.15 mm to 2.50 mm using the magnetizing press molding die according to claim 1, 2.
The magnetic press forming method characterized by performing press forming (deep drawing, overhanging, composite forming) while applying 10 to 100 Gauss magnetism to the magnetic metal thin plate.