JP3081058B2 - Semi-solid metal processing method - 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 the so-called thixoforging method, in which a material metal is heated to a semi-molten state and then flowed and filled into a mold using a punch and a die.

[0002]

2. Description of the Related Art The thixoforging method has been proposed by the applicant by inventing an improved conventional thixoforging method (reference number).
ASTP0938, filing date: March 14, 1992).
The thixoforging method has been used for the practical use of the thixocasting method, which has been studied a lot, and by simply improving the heating method, a forged product having a quality equal to or higher than that of the conventional method can be obtained. be able to.

In general, it takes a relatively long time to heat a material having a heat capacity that can be used for forging.
Furthermore, in the thixoforging method of the applicant, it is necessary to heat the inside and outside of the material while maintaining the temperature inside and outside the material until the liquidus ratio becomes 50% or more from the solidus line of the material.

[0004]

If the semi-molten state is maintained for a long time, the surface of the material is oxidized, and the oxide film covers the entire surface of the material. This oxide film may be mixed into the finished product during forging, causing a product defect.

On the other hand, in order to prevent this oxidation, it is possible to solve the problem by heating in an inert gas. However, for this purpose, there is a disadvantage that the equipment becomes large. For this reason, conventionally, even if an oxide film is formed, various measures have been taken so that the oxide film is not mixed into the finished product as much as possible (for example, Japanese Patent Publication No. 2-5170).
No. 3).

The present inventor has thoroughly observed the formation process of the oxide film when heating the billet, and as a result, found that a special phenomenon occurs in the formation of the oxide film on the outer surface of the billet. In other words, with the heating of the billet, an oxide film of a certain thickness is formed on the entire outer surface of the billet, and this oxide film formed on the outer surface of the billet with time passes downward due to its own weight. It is a phenomenon in which the oxide film at the bottom of the material gradually becomes thicker than that at the top of the material.

The present invention has been made in view of such a phenomenon, and an object of the present invention is to provide a semi-molten metal processing method in which an oxide film is not mixed into a finished product as much as possible.

[0008]

According to the present invention, a semi-molten billet inserted into a die is pressed by a punch,
In the semi-molten metal processing method of flowing and molding into the cavity formed in the mold, after heating the billet to a semi-molten state, insert the upper part at the time of heating into the die first, and punch It is characterized in that it is pressurized and flows toward the cavity.

[0009]

According to the present invention, the billet heated in a semi-molten state forms an oxide film on the entire surface, but the upper oxide film flows down by its own weight, and is stacked thickly. On the upper side, the oxide film is always formed thinner than that on the lower side. In the next forging step, the upper part at the time of heating is inserted into the die first, the lower part where the oxide film is formed thicker is inserted later, and the billet is pressed with a punch. Then, the thin portion of the oxide film first enters the cavity and is formed as a finished product. The thick portion of the oxide film remains in the die.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In the figure, reference numeral 1 denotes a semi-molten metal forging machine, which is a heating conveyor 2 for heating a material, a forming machine 3 for plastically deforming and forming an aluminum alloy material, and a forming machine 3 for transferring a heated material from the conveyor 2 to the forming machine 3. And a transfer robot 4 for transferring.

The heating conveyor 2 has a number of stainless steel transfer pallets 2a connected by a chain. A support 2b for supporting the billet B is provided on the transport pallet 2a, and is intermittently transported by a motor (not shown). Reference numeral 2c denotes a high-frequency induction heating coil installed on the top of the heating conveyor 2, which is provided so as to be able to move up and down. In addition, 2d shown in FIG. 3 is an electric furnace equipped with a conveyor 2e, 2f is a transfer robot for transferring the billet B from the conveyor 2e to the heating conveyor 2, and has a telescopic arm and a finger at its tip. . 1 and 2 show a case where the electric furnace 2d is omitted and all heating steps are performed by high-frequency induction heating.

The molding machine 3 has a main frame F having a die 3a for receiving the heated billet B, a punch 3b for pressing the billet B inserted into the die, and a mold 3c to which the material flows. . As shown in FIG. 5, the die 3a has a circular die hole 3 cooperating with the punch 3b.
d, and a liner 3e opened at the center of the bottom of the die hole 3d. The liner 3e forms a flow path for the semi-molten material metal to flow by being pressed by the punch 3b, and includes a vertical portion extending downward from the die hole 3d and a plurality of branching portions extending from the vicinity of the bottom and extending laterally. The horizontal portion communicates with a cavity 3h to be described later via a gate 3f. The mold 3c is attached to the main frame F
This is a so-called split type, which is divided into left and right parts by being supported by two left and right bar guides supported by the same.

Therefore, according to the embodiment shown in FIGS. 3 and 4, a large number of billets B are heated to a high temperature immediately below the solidus line in an electric furnace 2d in an inert atmosphere. Then, they are taken out one by one from there, the conveyor 2e,
f, and is placed on the support 2b of the heating conveyor 2.
The support 2b moves and stops intermittently at preset time intervals. Each time the transport pallet 2a stops, the coil 2c descends to perform induction heating from the outer periphery of the billet B. When the transport pallet 2a moves, the heating is interrupted and retracted upward. In this way, the billet B is heated to a temperature at which the billet B crosses the solidus of the material and reaches a semi-molten state in which the liquid phase and the solid phase are mixed before reaching the final step.

The transfer robot 4 is installed near the final step of the heating conveyor 2, and transfers the heated billet B to the molding machine 3 from the transfer pallet 2a. That is, as shown in FIG. 6, the transfer robot 4 is provided with a support shaft 4 arranged in a vertical direction.
a and a support arm 4b extending in the radial direction therefrom. The support arm 4b is provided with a telescopic arm 4c that can rotate and expand and contract itself, and has a bucket 4d for scooping up the billet B at the tip thereof. As shown in FIG. 8, the bucket 4d includes a thin rake plate 4e made of a heat-resistant metal such as a stainless steel plate, and a support member 4f erected there. The tip of the rake plate 4e is chamfered and plays a role of removing the oxide film formed on the lower surface of the billet B when scooping. In this embodiment, the supporting member 4f is formed of a stainless steel plate as the rake plate 4e as a semicircular side wall to supplement the rigidity of the bucket 4d composed of the thin rake plate 4e.

Therefore, the transfer robot 4 first has the telescopic arm 4c.
Is extended, and the bucket 4d is made to stand by at the position (1) in FIG. 2 until the heating of the billet B is completed and the coil 2c retreats upward, and is also preheated by the leakage magnetism of the coil 2c. Bucket 4d as shown in FIG.
In order to preheat the coil 2c, it is preferable to keep the gap as large as the diameter of the coil 2c. When the coil 2c retreats upward, as shown in FIGS. 8 and 9, the support arm 4b rotates to move the thin rake plate 4d of the bucket 4d provided at the tip between the support 2b of the transport pallet and the heated material. The bucket 4d is quickly pushed up into the space, and the support shaft 4a is rotated to lift the bucket 4d (2).
Is moved onto the molding machine 3 indicated by. When the bucket 4d scoops the billet B and reaches above the die hole 3d, FIG.
As shown in FIG. 5 described above, the support arm 4b pivots to invert the bucket 4c, and as a result, the billet B slides on the support member 4f erected on the rake plate 4e and slides into the die hole 3d. During heating, the pellet falls with the bellet B positioned above at the top.

The billet B is heated to a semi-molten state by the heating conveyor 2 to reach the process end, during which an oxide film grows on the surface of the material. The oxide film formed on the outer surface of the material gradually flows downward by its own weight, so that the upper oxide film becomes thinner and the lower oxide film becomes thicker. However, as described above, the billet B slides on the support member 4f erected on the rake plate 4e and falls into the die hole 3d with the billet B positioned above at the top during heating. As a result, when the billet B housed in the die hole 3d is strongly pressed by the punch 3b, the upper portion of the oxide film which is located at the time of heating first enters the cavity when heated, so that the contamination of the oxide film into the finished product is reduced. .

Thereafter, while the transfer robot 4 transfers the billet B to the die hole 3d, one transfer pallet 2a is sent on the heating conveyor 2, and the heating is performed by the coil 2c. Then, if the bucket 4d after the transfer is to return to the original standby position again, it collides with the coil 2c at the position (3). Therefore, the telescopic arm 4c is retracted and the support shaft 4a is rotated, and the initial angle is changed. After returning to the position, the telescopic arm 4c is advanced again to approach the coil 2c, and the preheating is performed. The billet B waits until the predetermined high temperature is reached.

[0018]

As described above, according to the present invention, when the billet B heated to a semi-molten state is inserted into the die 3, the upper portion at the time of heating is first placed in the die hole 3d. And pressurized by the punch 3b, so that the mixing of the oxide film into the finished product is reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a semi-solid metal forging machine.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view corresponding to FIG. 1, showing another embodiment.

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a sectional view taken along line VV in FIG. 2;

6 is a side view of the transfer robot 4. FIG.

FIG. 7 is a plan view thereof.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 2;

FIG. 9 is a sectional view corresponding to FIG. 8, showing a different step.

FIG. 10 is a sectional view corresponding to FIG. 8, showing a different step.

FIG. 11 is a characteristic diagram showing a magnetic flux density of the coil 2c.

[Explanation of symbols]

 2 ・ ・ ・ Heating conveyor 2d ・ ・ Electric furnace 2e ・ ・ Transfer conveyor 3a ・ ・ Dice 3b ・ ・ Punch 4 ・ ・ ・ Transport robot 4d ・ ・ Bucket

Claims (1)

(57) [Claims] In a semi-molten metal processing method in which a semi-molten billet inserted into a die is pressurized by a punch and flows into a cavity formed in a mold to form the billet, the billet is heated to a semi-molten state. A semi-molten metal processing method in which the upper part at the time of heating is inserted into a die first, and then pressurized with a punch to flow toward a cavity.