JP3088845B2 - Semi-solid metal forming equipment - Google Patents

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 semi-molten metal forming machine in which a light alloy is heated to a semi-molten state and then pressed into a mold by pressing with a punch. The present invention relates to an apparatus for preventing an oxide film generated at the time of heating a material from being mixed into the apparatus.

[0002]

2. Description of the Related Art In general, a so-called thixocasting method, in which a metal material is heated to a semi-molten state and then placed in a mold and molded, belongs to a publicly known technique (for example, Japanese Patent Application Laid-Open No. Hei 3-221253). ).

However, in this type of processing, the material is heated to a high temperature and the surface is easily oxidized. However, the oxide film enters the mold accompanying the material, and the oxide is mixed into the composition of the product and the oxide film is formed. The quality may be reduced.

Conventionally, in order to solve such a problem,
The material is heated and formed in an inert gas atmosphere to avoid the formation of an oxide film. However, there is a problem that the apparatus becomes large and the operating cost increases.

Further, in order to solve such a problem,
It has also been considered that the oxide film on the surface is left in the die and only the unoxidized portion inside is pressed into the mold.
That is, as shown in FIG.
A throttle step T is provided in a runner R connecting the cavity C with the cavity C. The throttle step T prevents movement of the oxide film and prevents the oxide film from flowing into the mold. S is a punch.

[0006]

However, even if such a stepped portion T is used, the movement of the oxide film is restricted by the stepped portion T.
And not only the oxide film facing the runner R, but also the oxide film on the bottom and side surfaces of the material M not facing the runner R proceeds to the runner R together with the oxide film and further into the cavity C. In some cases, the quality of the product after molding may be reduced.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a mold capable of minimizing the flow of an oxide film adhered to the surface of a material heated to a semi-molten state into a mold. The purpose is to obtain a machine, open a bottomed die hole in the die arranged in the forward direction of the punch,
In a semi-molten metal forming apparatus, a billet inserted into the die hole is pressed with a punch from above, fed through a runner opened at the bottom, and filled into a cavity provided at the other end of the runner. It is characterized in that a concave portion is provided at the bottom of the die hole.

[0008]

When a material in a semi-molten state is inserted into a die hole and strongly pressed by a punch, the runner flows downward with the part of the material facing the liner adhered to the tip of an unoxidized part inside. However, the portion of the material that does not face the liner, that is, the remaining portion of the bottom surface of the material and the oxide film formed on the side surface of the material are accommodated in the concave portions and are prevented from proceeding to the liner.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, reference numeral 1 denotes a molding die, which comprises a die 2 and a die 3 connected to the side thereof. Reference numeral 4 denotes a punch that cooperates with the die 2. In the die 2, a cylindrical billet B made of a light alloy such as magnesium or aluminum is heated to a region where a liquid phase and a solid phase are mixed, and is strongly pressed by the punch 4 and fed into the die 3.

First, a billet B used as a material is formed into a cylindrical shape having a diameter of 75 mm and a height of 60 mm made of AZ91 according to JIS standard, that is, a magnesium alloy containing 9% by mass of aluminum and 1% by mass of zinc. Have been.

In the die 2, a die hole 2a slightly larger than the diameter of the billet B and deeper than the height of the billet B is opened upward. At the center of the bottom of the die hole 2a, a runner 2b having a bottom having an area of about 1/3 thereof is drilled. The runner 2b branches from the runner 2b at a position slightly apart from the bottom by a distance to the die 3. The leading branch 2c is formed symmetrically (only the left branch is shown in FIG. 1,
The right branch has been omitted). Thus, the trap 2d for removing the oxide film contained in the tip portion of the material advancing the runner 2b below the branch 2c at the bottom of the runner 2b is formed.

Reference numeral 2f denotes an annular concave portion formed at the bottom of the die hole 2a, and 2e denotes an annular oxide film blocking wall formed between the concave portion 2f and the periphery of the runner 2b. The oxide film blocking wall 2e has a die hole 2a as shown in FIG.
Are formed integrally from the bottom surface, and the top is formed in a chevron to facilitate cutting the oxide film. In FIG. 2B, the oxide film blocking wall 2e is formed in a ring shape and is formed separately from the die 2. That is, the oxide film blocking wall 2e is made of inexpensive, high-temperature, high-hardness cast iron, and is detachably fitted to a step formed at the edge of the die hole 2a. And the upper edge is largely chamfered like in the case of FIG.

The die 3 comprises an upper die 3a and a lower die 3b which are vertically divided, and a cavity 3c is formed therebetween. Reference numeral 3d denotes a pin provided to be able to advance and retreat into the cavity 3c, and forms an axial hole in the product. 3e is a knockout for pushing the product out of the lower mold 3b,
3f is a gate.

Next, a molding process using the molding die 1 will be described. First, the billet B is heated to 580 ° C. by high frequency or low frequency induction heating in an inert atmosphere. At this time, the magnesium alloy is in a semi-molten state composed of a liquid phase component and a solid phase component, and at this time, the ratio of the liquid phase is about 65%.

Next, this is inserted into the die hole 2 a and strongly pressed by the punch 4. The underside of billet B is runner 2b
Is pressed against the oxide film blocking wall 2e formed around the substrate, and the oxide film on the surface is cut into a disk shape. Then, it is extruded into the runner 2b with an undivided disk-shaped oxide film adhered to the head of the non-oxidized portion inside. When the bottom of the runner 2b is reached, that is, when the trap 2d is filled with the material that has flowed out, a portion of the upper portion of the trap 2d that does not include an oxide film swells into the branch 2c, and fills the cavity 3c therethrough. When the leading portion reaches the trap 2d, the oxide film of the leading portion is taken into the trap 2d together with the unoxidized portion inside, and does not flow into the cavity 3c. Also, the portion of the material not facing the liner 2b,
That is, the remaining portion of the lower surface of the billet B (annular)
The oxide film formed on the side of the material or material is the oxide film blocking wall 2
e is almost prevented from being drawn into the liner 2b,
It is taken into the recess 2f.

The billet B is initially in a semi-molten state and is slightly cooled in the die holes 2a and the runners 2b, while reaching the cavities 3c without deteriorating the fluidity due to plastic deformation when passing through the holes. . The time from when the billet B is extruded into the runner 2b to when it fills the cavity 3c is about 2 seconds. After filling, the molding is completed by applying a further high pressure for 5 seconds. Thereafter, the pin 3d is pulled out, the mold is opened, and the knockout 3e is operated to take out the product. At this time, the portion including the oxide film left in the die 2 by dividing the die 2b into left and right, that is, in the runner 2b, the branch 2c, and the concave portion 2f is taken out together with the product.

FIGS. 3 and 4 show modified examples of the concave portion 2f formed at the bottom of the die hole 2a and the oxide film blocking wall 2e. The concave portion 2f is different from the concave portion 2f of FIG. 2 in that the concave portion 2f is formed in an annular shape, but is formed in four islands at predetermined intervals. Also, the oxide film blocking wall 2e formed between the island-shaped concave portion 2f and the periphery of the runner 2b is discontinuous.

In the present invention, it goes without saying that the concave portion 2f at the bottom of the die hole 2a may be formed in an annular shape or an island shape. Further, in this embodiment, an example in which the billet is pressed from above by punching is shown.However, the present invention does not mean upward in the direction of gravity, but includes one performed from the top, bottom, left and right in the direction of gravity. Needless to say.

[0019]

As described above, according to the present invention, since the concave portion is provided at the bottom of the die hole, when the heated billet, which is a material, is pressed by a punch, the oxidized surface of the billet is removed from the runner. The portion facing the surface is cut and not fragmented, so it is easy to remove it. In addition, the remaining oxide film is housed in the concave portion and is almost prevented from being drawn into the runner. Is minimized, and there is an effect that a molded article of excellent quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die 1. FIG.

FIG. 2 is a sectional view of a main part thereof.

FIG. 3 is a sectional view of a main part according to another embodiment.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a sectional view showing a conventional molding die.

[Explanation of symbols]

 2 ... Die 2a ... Die hole 2b ... Runner 2e ... Oxide film blocking wall 2f ... Recess 3c ... Cavity 4 ... Punch B ... Billet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 18/02 B22D 17/00 B22D 17/20

Claims (1)

(57) [Claims] 1. A die having a bottom is opened in a die arranged in the forward direction of the punch, and a billet inserted in the die is pressed from above with a punch, and fed through a runner opened in the bottom. Then, in a semi-solid metal forming apparatus that is intended to fill the cavity provided at the other end of the runner,
A semi-molten metal forming apparatus, wherein a concave portion is provided at the bottom of the die hole.