JPH0751760A - Production of strength parts for automobile by detonation pressure - Google Patents

Abstract

PURPOSE:To produce the strength parts made of high tensile steel plates for automobiles by generating the pressure of detonation by ignition of a combustible gaseous mixture as a liquid pressure or elastic pressure and pressing primary molded goods via a film member or directly to second molds. CONSTITUTION:A pressure chamber 32 is connected to the bottom end 21B of a combustion chamber 21 and rubber 4 is housed as a pressure medium in a pressure chamber 32 and is provided right thereunder with a molding device 33. The upper part of this rubber 4 directly faces the bottom end 21B of the combustion chamber 21. A pipe 34 for air venting and a liquid supplying pipe 35 for water, etc., for liquid pressure are connected via valves to the pressure chamber 32. The high-liquid pressure or elastic pressure is generated and impulsive waves are propagated in the circular conical part of the rubber 4 from above to below, by which the high impact pressure is applied on the inner side of the primary molded goods 5. The side wall parts of the primary molded goods 5 receive tensile force and high surface pressure at this time and, therefore, the shape thereof is corrected. As a result, the strength parts for automobiles having good dimensional accuracy are obtd.

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 strong springback material such as a high-strength steel plate or an aluminum alloy thin plate into a strength part for an automobile.

[0002]

2. Description of the Related Art Conventionally, cold-rolled steel sheets have been widely used as sheet materials for forming and processing of automobile strength parts and the like, but in recent years, in order to improve fuel efficiency of automobiles, there is an increasing demand for weight reduction of vehicle bodies. High-strength steel sheets are used in automobile strength parts to satisfy the requirements.

Since the elongation of a high-tensile steel plate decreases as the strength increases, as compared with a soft cold-rolled steel plate for general press forming, shape defects due to forming cracks and springback are more likely to occur, and the press formability is much higher. descend. Therefore,
At present, the most commonly used in actual press molding is a tensile strength of 60 kg / mm ² stop. In order to realize further weight reduction of the vehicle body, the tensile strength is 80kg.
It is desired to establish a method for forming a high-strength steel sheet having a thickness of / mm ² or more.

An impact molding method has been conventionally known as an effective method for straightening a molded product of such a material having a large springback by molding. Liquid or a medium equivalent to this is preferable as the impact force transmission medium in impact molding, but this is because there is a big difference in the shape of the part before correction by molding because the springback characteristics differ depending on the material strength. This is because it is important that they are easily blended and the impact force is transmitted.

Several methods are known as the impact hydraulic method. First of all, by hitting a bullet into a liquid such as water for pressurization, an impact hydraulic pressure is generated in the liquid, and the pressure is applied to a molded member such as a plate material to press the member against a mold. An impact hydraulic pressure generating device for a three-dimensional molding is disclosed in Japanese Patent Laid-Open No. 01-157.
No. 725 is proposed.

Secondly, there is also known an explosive molding apparatus which generates an impact water pressure by burning explosives in water and presses a thin plate as a member to be molded into a mold by the pressure to perform three-dimensional molding. ing. This device is mainly used for molding large parts.

Further, thirdly, an impact hydraulic pressure is generated by causing a piston accelerated at high speed by gas pressure to collide with the liquid surface of the liquid for pressurization contained in the container,
An apparatus is also known in which the member to be molded is pressed by a hydraulic pressure into a mold to mold the member. The device is used for molding relatively small parts.

[0008]

However, as long as the method of molding by impact hydraulic pressure by the above-mentioned first to third devices is used, there are common or unique problems as follows. (1) Use dangerous and expensive explosives. (2) There is a risk that there are restrictions on the installation location.

(3) It is difficult to significantly change the ultimate pressure. (4) Not suitable for repeated operation in a short time. (5) Large-scale equipment is required. (6) It is necessary to replace moving parts such as pistons.

(7) Since the structure of the device is complicated, maintenance,
Difficult to perform inspections. The present invention has been made in order to solve the problems caused by the above-mentioned conventional methods, is safe, can be repeatedly operated in a short time, and can correct the shape of high-strength automotive strength parts. It is an object of the present invention to provide a method for manufacturing a strength component for an automobile by pressure.

[0011]

In the method of manufacturing a strength component for automobiles by detonation pressure according to the present invention, a thin plate is press molded or hydraulically molded using a first molding die to manufacture a primary molded product. After that, the primary molded product is placed on the second mold, and the detonation wave generated by igniting the combustible air-fuel mixture is converged with its progress, and the high pressure obtained at the converging portion can be directly or exchanged. It is transmitted to a pressure medium composed of a liquid or an elastic body through a membrane to convert it into hydraulic pressure or elastic pressure,
The shape is corrected by pressing the primary molded product to the second mold through the film body or directly by the hydraulic pressure or elastic pressure.

[0012]

The method of manufacturing a strength component for an automobile by detonation pressure according to the present invention is performed by the following steps. The forming depth is made smaller than a predetermined value so that the thin plate is free from forming cracks, and the first forming die is used for press forming or hydraulic forming to obtain a primary formed product. The primary molded product is set on the second mold having the shape of the final molded product of the molding apparatus using the detonation pressure.

The ignition chamber of the molding apparatus is filled with a combustible gas mixture having a theoretical mixing ratio and ignited. When ignited, the flame is detonated,
It travels in a combustion chamber whose cross-sectional area gradually decreases through a plurality of guide paths. At that time, since each taxiway has the same path length,
The flame of each induction path reaches the minimum end of the cross-sectional area of the combustion chamber at the same time. At the end of the minimum cross-sectional area of the combustion chamber, the flame converges, so the pressure of the flame increases and reaches the maximum pressure.

This pressure is transmitted to the pressure medium (liquid or elastic body) of the pressure chamber connected to the combustion chamber. The pressure transmitted to the pressure medium becomes a hydraulic pressure or an elastic pressure, and the primary molded product is pressed against the second mold through the film body or directly, and is molded into a strength part for automobile of a final product shape. .

[0015]

EXAMPLE A method for manufacturing a strength component for automobile by detonation pressure according to an example of the present invention will be described below. As a member used for a strength part of an automobile, there are many channels 1 having a hat cross section as shown in FIG. And, in general, this hat cross-section channel 1 is often used in a model test for evaluating the shape correction effect.

Therefore, tensile strength 120 kgf / mm ² , thickness 1.6 mmx
The cold-rolled steel plate 2 having a width of 40 mm and a length of 220 mm was subjected to primary forming by a press with a die 3 as shown in FIG. 2 under the conditions of a wrinkle holding force of 3.4 tons and a forming height of 39 mm. Next, the rubber 4 having the shape as shown in FIG. 3 was used as a medium for transmitting a shock wave by convergent detonation to correct the shape of the primary molded product 5.

FIG. 4 shows a device for correcting the shape of a hat cross section channel by convergent detonation. In this shape correcting device, the combustion chamber 21 has a conical shape directed downward, and the cross-sectional area in the cross section is maximum at the upper end 21A and the lower end 21B.
At the minimum, the converging part is formed. The inner wall of the upper end portion 21A of the combustion chamber 21 is curved slightly upward, and a plurality of hole-shaped guide passages 22 communicate therewith. The plurality of guide paths 22 are converged on the upper side into a disk-shaped dispersion chamber 23. The dispersion chamber 23 is connected to an ignition chamber 24 extending upward. And the ignition chamber 2
A spark plug 25 operated by an ignition device 26 is provided on the upper part of the spark plug 25.
Is provided, and a fuel supply source 29 and an oxidant supply source 30 are connected via flowmeters 27 and 28, respectively. In addition, 31 is a pressure gauge for confirming the pressure in the ignition chamber 24.

A lower end portion 21B of the combustion chamber 21 is opened, and a pressure chamber 32 is connected thereto. The rubber 4 is housed in the pressure chamber 32 as a pressure medium. A molding device 33 is provided immediately below it. The upper portion 4a of the rubber 4 is the combustion chamber 21 as shown in the figure.
Directly facing the lower end 21B of the. A pipe 34 for venting air is connected to the pressure chamber 32 via a valve, and a liquid supply device 35 such as water for hydraulic pressure is connected via a valve.

A molding die 36 for shape correction is replaceably housed inside the molding device 33. Between the molding device 33 and the pressure chamber 32, it is possible to hold the peripheral edge of the primary molded product P of the strength component for automobile which undergoes the shape correction between the flanges. The molding device 33 includes
A vacuum pump device 37 is connected to penetrate the molding die 36 and communicate with the upper space thereof to create a vacuum in the space. The vacuum pump device 37 is also connected to the ignition chamber 24 described above.

High-pressure liquid pressure or elastic pressure is generated by this apparatus, and the shape correction for making the primary molded product 5 into the final shape by utilizing this is performed as follows. A shock wave is propagated from the upper part to the lower part of the conical portion of the rubber 4 to apply a very high shock pressure to the inside of the primary molded product 5. Then,
It is molded up to 40 mm, which is 1 mm deeper than the primary molded product 5. At this time, the side wall of the primary molded product 5 receives a tensile force and a high surface pressure, so that the shape is corrected.

A measuring method of dimensional accuracy is shown in FIG. span
Using a dial gauge 7 having two 20 mm legs 6, the height of deviation from the horizontal position at a span of 20 mm is measured, and the wall warp ρ is measured, and the hat section die wall 5a of the primary molded product 5 is measured. The angle θd formed by the flange 5b and the wall 5
The angle θp formed by a and the bottom portion 5c was measured. As a result, the wall warpage ρ was corrected from 0.72 mm to 0.02 mm before correction. Also, the die shoulder angle θd and the punch shoulder angle θp are
Before correction, they had been corrected from 86 ° and 108 ° respectively to both 91 °.

On the other hand, the primary press-molded product 5 was subjected to restrike as a shape correction method using a press, which is normally used, instead of impact molding by convergent detonation. In this case, the condition for the wrinkle holding force was 15 tons, which was close to the breaking limit, and was processed from a height of 39 mm before restriking to 40 mm.
The result is wall warpage ρ = 0.25 mm and die shoulder angle θ
d = 88 °, punch shoulder angle θp = 95 °, which is considerably corrected compared to the primary press-formed product, but at a practically acceptable level (ρ <0.10 mm, θd <2 °, θp <2 °) It turns out that it hasn't arrived.

On the other hand, it has been found that straightening by convergent detonation clears these allowable levels and that even a high-strength steel sheet having a tensile strength of 120 kgf / mm2 strength can be sufficiently straightened.

[0024]

As described above, according to the manufacturing of the high-strength steel plate automobile strength component using the convergent detonation molding of the present invention, the high-strength steel plate automobile strength component having a shape which cannot be obtained by the conventional press molding is manufactured. It becomes possible to realize further weight reduction of automobiles.

Further, according to the device of the present invention, unlike the conventional bullet driving type and explosive type, since no explosive is used, the device is not restricted by the setting, and the impact pressure can be continuously generated. This has the effect that it can be converted to a mass production system.

[Brief description of drawings]

FIG. 1 is a perspective view of a hat cross-section channel.

FIG. 2 is a cross-sectional view showing a primary molded product and a mold.

FIG. 3 is a perspective view showing a relative positional relationship between a pressure medium and a primary molded product.

FIG. 4 is a vertical cross-sectional view of a shape correcting device used for correcting the shape of a primary molded product.

FIG. 5 is an explanatory diagram showing a method for measuring the shape of a molded product after shape correction.

[Explanation of symbols]

 1 Hat Section Channel 2 Cold Rolled Steel Sheet 3 Mold 4 Rubber for Pressure Medium 5 Primary Molding 6 Leg of Dial Gauge 7 Dial Gauge 21 Combustion Chamber 22 Guideway 23 Dispersion Chamber 24 Ignition Chamber 25 Spark Plug 26 Ignition Device 27, 28 Flowmeter 29 Fuel supply source 30 Oxidant supply source 31 Pressure gauge 32 Pressure chamber 33 Molding device 34 Air venting pipe 35 Liquid supply device 36 Molding die 37 Vacuum pump

Claims (1)

[Claims] 1. A thin plate is press-molded or hydraulically molded using a first mold to produce a primary molded product, and then the primary molded product is placed on a second mold to form a flammable mixture. The detonation wave generated by igniting the air is converged as it progresses, and the high pressure obtained at the converging part is transmitted to the pressure medium composed of a liquid or an elastic body directly or through a replaceable membrane body to hydraulic or elastic pressure. A method for manufacturing a strength component for automobiles, characterized by converting the primary molded product to the second mold by the liquid pressure or elastic pressure through the film body or directly to correct the shape.