JPH05228602A - Formation of metal material - Google Patents

Abstract

PURPOSE:To facilitate finishing formation and to contrive to obtain a high strength owing to a clear grain flow by heating a blank having granular structure to solid-liquid coexistent temp. range and preforming. CONSTITUTION:At the time of heating the metal blank 7 having granular structure fed to a sleeve 4 for supplying the blank to the temp. of the solid-liquid coexistent range by a heating coil 10, by working a plunger 8, the blank 7 is fed into a cavity 3 in a die to form the preformed body. After the blank 7 is pressurized and solidified in the die, the preformed body is taken out and after heating to the temp. of the solidus or lower in a heating furnace, plastic working is applied and further, the necessary part is finish-formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a forming method by plastic working which causes a metal flow such as press forging.

[0002]

2. Description of the Related Art There are various methods for forming a metal material, but in general, a forming method by press forging is widely used for forming structural parts in terms of strength and reliability. In press forging, a material is processed at a temperature below its solidus and given a shape. As the material, in order to eliminate casting defects, a round bar or an ingot extruded or rolled from the ingot is pre-forged. In the normal forging process,
Using these materials, depending on the complexity of the product shape,
Rough ground forming, that is, preforming and finish forming are performed in several stages. This preforming is a forming for forging with a finishing die, and the purpose is to distribute the volume so that an appropriate metal flow is produced in the finishing die forging so that a forging defect does not occur. Molded products molded through such steps,
Since it has a metal flow, it has high strength, and casting defects have disappeared, resulting in high quality.

On the other hand, as disclosed in Japanese Patent Publication No. 58748/1983 and Japanese Unexamined Patent Publication No. 13259/1983, as a method of molding a component having a complicated shape, the metal of the material is in a solid-liquid coexisting region, that is, a semi-melting temperature. There is a method to form the final product in the area. The method of processing a metal in a solid-liquid coexisting region generally has good fluidity, and thus requires only a small processing force, and is advantageous for forming complicated shaped parts and difficult-to-process materials.

[0004]

However, in press forging, there is a drawback that the manufacturing cost becomes high because the forming process is complicated. On the other hand, in the method of molding in the solid-liquid coexistence region, the moldability is good, so the molding process can be simplified, but in the case of forging because the fluidity of the material is good in the solid-liquid coexistence region. As described above, there is a drawback that a clear plastic flow, that is, a grain flow is not formed, and the strength of the product does not reach the level of the forged product.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a molding method for a metal material, which is easy and easy to mold, and which can achieve high strength by clear grain flow.

[0006]

According to the forming method of the present invention, a metal material is preformed into a shape close to a product shape, and then the preformed body is subjected to plastic working in a temperature range below the solidus line of the material. In the method of forming a metal material by applying and finish forming,
A metal material having a granular structure is preformed in the solid-liquid coexisting temperature range of the material. At this time, finish forming may be performed on a part of the preformed body, if necessary.

[0007]

[Function] When preforming a metal material, a material having a granular structure is used, and the material is heated in a solid-liquid coexistence region to be formed.
The material has extremely good fluidity, and even if it is a product with a complicated shape, it requires multiple steps in the conventional forging process as well as preforming of the rough shape, but it is almost the same shape as the final product in one molding It can be molded. Moreover, the preformed body formed in this way stops the grain structure of the material, and then the whole or a part of the preformed body is further finished in the solid phase region by plastic working such as forging and die forging. Even when molding is performed, the moldability is extremely good. By this finishing process, plastic flow, that is, grain flow can be given to all or part of the preform, and bubbles remaining inside can be eliminated, and good characteristics similar to those of forged products can be obtained. ..

[0008]

EXAMPLES First, the crystal structure of the metal material used in the present invention will be described. In processing in the solid-liquid coexistence region, in order to obtain extremely good fluidity of the material, the material structure must be a granular structure, not the dendritic structure (dendritic structure) found in cast materials. ..
Such a granular structure can be obtained by rotating and stirring a metal in a solid-liquid coexisting region by a mechanical method or an electromagnetic method and then solidifying it, or by adding a grain refiner such as Ti or Zr, or by low temperature casting. Can be realized by Further, as in the case of the conventional forging process, a granular structure may be formed by extruding from an ingot, rolling, or preliminary forging.

The material of the metal material is not limited to low melting point metals such as aluminum and its alloys and magnesium alloys, but is also applicable to high melting point metals such as copper alloys and steels. Next, the molding conditions in the solid-liquid coexistence region, which is the preforming step, will be described. The solid phase fraction of the raw material when heated in the solid-liquid coexisting region is preferably in the range of 0.8 to 0.2. When the solid phase fraction is 0.8 or more, the fluidity of the material is lowered, the filling property in the mold is deteriorated, the material is cracked, and the molding load is increased, which is not preferable. Further, when the solid phase fraction is less than 0.2, generally, the temperature difference between the temperature corresponding to such a low solid phase fraction and the liquidus line is extremely small, and thus the temperature control becomes difficult. Regarding the mold temperature at the time of molding, when the mold temperature is around room temperature, the surface quality is deteriorated, such as the occurrence of fine cracks on the surface of the molding material, and the filling of the material into the mold is reduced. ..
Therefore, the mold is usually heated to 50 ° C or higher, preferably 100 ° C or higher. Also, regarding the molding speed,
If the molding speed is low, the solid-liquid coexistence process is performed, and the solid phase and the liquid phase may separate during the molding process, causing macro segregation in the cross section of the molding material. It is desirable that the ram speed) is approximately 100 mm / S or higher.

In molding in the solid-liquid coexisting region, in order to prevent generation of pores due to solidification shrinkage in the mold and deformation of the molding material at the time of mold release, the material is completely pressurized in the mold. It is desirable to coagulate it. Further, regarding heating and forming of a metal material, the metal material which is once solidified into a granular structure may be supplied to a forming machine and heated, or the solidified metal material may be solidified without being solidified once. Alternatively, the granular solid phase and the liquid phase may coexist in the state where they are supplied to the molding machine and molded into a state close to the final product.

FIG. 1 shows an example of a molding apparatus for preforming, in which a molding cavity 3 of an arm molding die composed of an upper mold 1 and a lower mold 2 is used for supplying a material. One end of the sleeve 4 is continuously connected via the jigs 5 and 6, and the other end is for pressurizing and supplying the metal material 7 having a granular structure, which is inserted into the sleeve 4, into the forming cavity 3. The tip 9 of the plunger 8 is slidably fitted. A heating coil 10 for high-frequency heating the metal material 7 to a desired temperature in the solid-liquid coexistence region is wound around the outer periphery of the plunger 4 side end of the sleeve 4.

According to this apparatus, when the material 7 heated by the heating coil 10 reaches a predetermined temperature in the solid-liquid coexistence region, the plunger 8 is quickly activated to move the material 7 into the cavity 3 of the mold. And the preform is molded. Since the material has a granular structure, it has extremely good fluidity in the solid-liquid coexisting region and completely fills the cavity 3. After solidifying under pressure in the mold, the upper mold 1 and the lower mold 2 are opened and the preform is mechanically taken out. Incidentally, FIG. 2 shows the upper mold 1
Then, a plan view of the molding cavity 3 constituted by the lower mold 2 is shown, and the metal material 7 is fed into the cavity 3 through the groove 11.

The molded body preliminarily molded as described above is further heated in a heating furnace to a temperature below a predetermined solidus, and then a molding machine incorporating a finishing die is used to remove all or a required portion of the molded body. Finish forging to obtain the desired product. Next, specific examples will be given. A 6061 alloy having a diameter of about 80 mm and having a grain structure by adding a predetermined amount of a grain refiner Ti-B has a solid phase fraction of about 0.6 at the solid-liquid coexistence region (about 6
After heating to 30 ° C), it is rapidly fed into the arm forming mold at a plunger speed of about 400 mm / S as shown in Fig. 1, and is solidified under pressure with a pressing force of about 6 kg / mm ² in one run. Molded. This preform was subjected to finish forging at a temperature of about 450 ° C. and then subjected to T6 treatment. The mechanical properties obtained are a tensile strength of about 32 kg / mm ² and an elongation of about 15%, the minimum standard value of JIS standard for die forging of the same alloy Tensile strength 26.5 kg / mm
^2. Greatly exceeded the elongation of 7%, and obtained the same characteristics as the current forged products in both tensile strength and elongation.

[0014]

As described above, the method for forming a metal material according to the present invention utilizes the good fluidity of the material in the solid-liquid coexistence region to form a material close to the final product, and then the preform. By performing finish forming by plastic working such as forging on all or part of it, it is possible to give plastic flow, that is, Glenflow to the finished formed part and to eliminate bubbles remaining inside, A component having good characteristics can be easily manufactured by a process simpler than the conventional process, which improves productivity and reduces cost. Furthermore, since the deformation resistance of the material is extremely small in the solid-liquid coexistence region, the processing force required for molding can be smaller than in the conventional process, and the molding machine can be made compact and the equipment cost can be reduced. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a preforming apparatus according to an embodiment.

FIG. 2 is a plan view of a molding cavity of the arm molding die according to the embodiment.

[Explanation of symbols]

 3 Molding cavity 7 Metal material 8 Plunger 10 Heating coil

Claims (1)

[Claims] 1. A method for forming a metal material, comprising preforming a metal material into a shape similar to a product shape, and then subjecting the preformed body to a plastic working in a temperature range below the solidus line of the material to finish-form. A method for forming a metal material, which comprises preforming a metal material having a granular structure in a solid-liquid coexisting temperature range of the material.