JP3471402B2 - Forming method of aluminum or aluminum alloy plate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic molding method for aluminum and aluminum alloy sheets, and is applicable to molding of automobile parts, electric equipment parts, aircraft parts, objects and the like. The present invention relates to a molding method effective for difficult complicated shapes. 2. Description of the Related Art In recent years,
In light of environmental issues such as global warming and destruction of the ozone layer, reducing the weight of automobiles is being studied in earnest in order to suppress the increase in atmospheric carbon dioxide and the like. There are various methods of weight reduction, but replacement of materials, that is, the use of aluminum or aluminum alloy plates in place of steel plates that have been mainly used in the past, has been studied to promote weight reduction, and the amount of use has been increasing. I am doing it. However, since the formability of an aluminum or aluminum alloy plate is inferior to that of a steel plate, there is a strong need for improvement in terms of materials and press forming methods. Conventionally, when aluminum and aluminum alloy plates are applied as molding materials for automobile parts, electric equipment parts, aircraft parts, equipment, and the like, the formability of ordinary press molding is limited, and molding is particularly severe. In the case of molding into a part having a complicated shape, the molding process must be performed by dividing the pressing process into a plurality of times, and a cost increase due to an increase in the number of processes is inevitable. [0004] In response to the above demands, in terms of materials, attempts have been made to improve the formability of the material by optimizing the composition of the aluminum material and the manufacturing process, as proposed in JP-A-63-89649. It has been done. However, in recent years, there has been a growing demand for forming into more complicated and complicated shapes, and it is not sufficient to improve only materials. On the other hand, with respect to the molding surface, the present inventors have proposed a molding method utilizing the improvement of the characteristics of aluminum at low temperatures as previously proposed in JP-A-4-3000032 and JP-A-4-194762. Has been developed. However, the present inventors further studied and found that no improvement in moldability was observed even with this molding method. Therefore, it is necessary to take measures to improve the moldability while effectively utilizing the advantages of this molding method. [0006] Under such circumstances, an object of the present invention is to provide a method of forming an aluminum or aluminum alloy plate which can improve the formability by further improving the formability method proposed above. And [0007] The aluminum according to the present invention.
Molding method of beam or an aluminum alloy plate, forming an aluminum or aluminum alloy plate by cryogenic aluminum
Press in the method of forming the aluminum or aluminum alloy plate
Average molding rate of the molded is at 10 mm / sec or more, material
A molding temperature of -50 to -196 ° C., forming the start or
The holding time of the wrinkle pressure is T seconds, the starting temperature of the material molding
When degrees was used as a t ° C., characterized by the this <br/> that satisfies T ≦ √ (50-t) . The present invention will be described below in more detail. First, the reasons for limiting the materials will be described.
Aluminum and aluminum alloys are disclosed in the aforementioned Japanese Patent Laid-Open No. Hei 4-30003.
As shown in No. 2, it does not become brittle at a low temperature, and on the contrary, strength and elongation are improved. Therefore, the applicable materials are aluminum and aluminum alloy plates. The aluminum alloy material is not limited as long as it has a component system and a composition that can be used for forming, but among aluminum alloys, an Al-Mg alloy having excellent forming properties at room temperature is preferable. The same applies to a metal material having a face-centered cubic lattice, such as copper, and the present invention may be applied to such a material. Next, the reasons for limiting the conditions in the present molding method will be described. The lower the material temperature during molding is, the better the temperature is. However, if the temperature is higher than -50 ° C, the effect of improving the moldability is small, and if the temperature is lower than -196 ° C, it is necessary to use an expensive cooling medium such as liquid helium. There is a cost increase. Therefore, the material temperature during molding is -50 to 1
Limited to 96 ° C. In addition, from the viewpoint of the contribution to the improvement of the material properties, the range of -100 to -196 ° C is desirable. The speed at the time of molding is important for maintaining the material temperature at the time of molding. In particular, the average speed at the time of molding is 10 mm / mm.
If it is less than sec, the temperature rises, so that the improvement of the material properties at low temperature cannot be utilized, and the improvement of the moldability is not recognized. Therefore, the average forming speed of the press at the time of forming is set to 10 mm / s or more. Note that there are mechanical presses and hydraulic presses as press machines, but it is desirable to use a mechanical press. Although the moldability is improved under the above molding conditions,
Furthermore, the time for holding wrinkle pressure until the start of molding (T)
It is preferable to regulate the temperature of the material because it greatly affects the temperature of the material. That is, the cooling temperature of the raw material rises sharply as the temperature decreases, and this temperature rise shows a parabolic change. At this time, if the pressure holding time is long, the temperature of the material at the time of molding is increased, and when the molding start temperature of the material is t ° C., T
Is larger than 場合 (50-t), it has been found that the moldability is lowered. Therefore, it is preferable that the wrinkle pressing pressure holding time T (second) until the start of molding is restricted to √ (50−t) or less. In addition, it is desirable to use a single-acting system in which molding is started almost simultaneously when a wrinkle pressing force is applied. It is to be noted that an appropriate method can be used as a method for cooling the material. For example, various types of refrigerants may be used, or the material may be immersed in the refrigerant, cooled, taken out, and then used for molding. And the like. Next, an embodiment of the present invention will be described. EXAMPLE A 1 mm thick JIS5182 alloy O material was used as a molding material, and a molding test was conducted with a cylindrical flat mold shown in FIG. 1 using a crank press and a hydraulic deep drawing tester.
At that time, a commercially available mineral oil (viscosity 3.5 c
(St / 40 ° C.), the material coated with lubricating oil was immersed in liquid nitrogen for 2 minutes, cooled, and then subjected to a test. The superiority of the moldability was determined by changing the bottom dead center of the press to gradually increase the height of the molded product and determining the molding limit height at which the molded product cracked. The results show that, as shown in Table 1, in the hydraulic deep drawing tester, when the speed is low, and even when the speed is high, the forming start temperature is lowered when the time for applying the wrinkle pressing force is long. Even though there is no improvement in the molding limit height,
When the speed was high and the time during which the wrinkle pressing force was applied was short, an increase in the forming limit height was observed with a decrease in temperature. Further, in the case of a mechanical press, the molding height increases as the temperature decreases, and in particular, the effect of improving the molding limit height is great. [Table 1] As described in detail above, according to the present invention,
The molding is severe, and aluminum and aluminum alloy plates can be used for various molded products having complicated shapes, which can greatly contribute to reducing the weight of products.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a mold and a test procedure for a molding test.

Continuation of the front page (56) References JP-A-5-247480 (JP, A) JP-A-4-300032 (JP, A) JP-A-6-154894 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B21D 22/00-26/14 B21D 37/16

Claims (1)

(57) [Claims 1 aluminum or an aluminum alloy plate
Aluminum or aluminum alloy plate formed at cryogenic temperature
In the molding method , the average molding speed of press molding is 10
mm / sec or more, and the molding temperature of the material is -50 to-
196 ° C, wrinkle holding pressure is maintained until molding starts
When the time is T seconds and the molding start temperature of the material is t ° C., T ≦ T
Aluminum characterized by satisfying √ (50-t)
Forming method of aluminum or aluminum alloy plate .