JPH08164414A - Die for extruding aluminum and extruded shape excellent in surface property - Google Patents

Abstract

PURPOSE: To provide an extruding die suitable for manufacturing an aluminum extruded shape of high quality. CONSTITUTION: This extruding die is used for extruding an aluminum material into the target shape by hot extrusion and a radius (R) of 0.3-1.5mm is provided in the edge part 7 between a bearing face 6 and the surface 9 of the die with which a slit 5 is divided. It is preferable that the surface 9 of the die in the periphery of the slit is formed at right angles to the bearing face 6. Surface hard layers by nitriding treatment may be formed on the bearing face and surface of the die. Then, by controlling the shape of the edge part 7, the aluminum extruded shape having small surface roughness and high glossiness for a long time is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing die used for producing an aluminum extruded shape material having a highly stable surface property and an extruded shape material obtained by using the processing die.

[0002]

2. Description of the Related Art Regarding extrusion of aluminum and aluminum alloys,
In order to improve the mechanical properties and obtain an extruded shape member having no surface defects, investigations and studies have been conducted from various viewpoints. Regarding cold extrusion and hydrostatic extrusion, the mechanism that causes deterioration of mechanical properties and surface defects is being clarified, and various measures effective for improving mechanical properties and eliminating surface defects are proposed accordingly. Has been done. On the other hand, in hot extrusion, the deformation resistance of the material decreases as the processing temperature rises, the friction resistance between the processing die and the material surface, the temperature distribution, etc. differ, and aluminum or aluminum alloy is extruded with a complicated behavior. .

Regarding hot extrusion, "Plasticity and processing" No. 1
Vol. 7, No. 191 (1976-12), pp. 951 to 957, analyzes the processing pressure from the metal flow during hot extrusion, and reports that optimum results are obtained when the bearing introduction angle is 90 degrees. There is. However, the mechanism of deterioration of mechanical properties and generation of surface defects has not been fully clarified, and there are very few studies that are effective in improving mechanical properties and elimination of surface defects. Generally, in an extrusion die, the larger the bearing area, the greater the friction between the bearing surface and the material, and the higher the pressure required for extrusion. Therefore, in the conventional extrusion die, in order to reduce the metal flow along the curved surface of the edge portion in order to reduce the extrusion pressure, the edge portion of R≈0 mm has been considered effective. In order to prepare an extrusion die having an edge portion of R≈0 mm, the surface of the bearing portion was smoothed by hand grinding or the like after finishing the electric discharge machining. Further, the bearing edge portion was also finished by flat polishing after removing burrs and the like.

[0004]

Even if the extrusion die having the improved shape of the bearing is used,
Surface defects such as streaks and pickups are likely to occur in the extruded profile extruded by hot extrusion, and it is difficult to obtain high quality products. The extruded profile having surface defects cannot be used as a product, which causes a decrease in yield and thus an increase in manufacturing cost. The edge tip of the bearing portion is a sharp corner portion as shown in FIG. The aluminum material during extrusion produces a metal flow of arrows along the surface of the extrusion die. Therefore, the sharp corners where the load is concentrated are likely to be worn or chipped, and the surface layer separated from the die body is mixed into the extruded profile. As a result, defects such as streaks and pickups occur in the extruded profile.

The corners are often worn or chipped especially in the extrusion die whose surface is hardened by the nitriding treatment. On the surface of the nitriding die, as shown in the figure, a nitrogen diffusion layer or a nitride layer made of a white layer is formed. The reaction at the time of nitriding progresses more actively in the sharp corners,
As a result, a thick white layer grows thick at the edge. On the other hand,
Since an excessive load is applied to the edge portion by the metal flow, the hard and brittle white layer easily separates from the edge portion having a sharp corner portion, which promotes the occurrence of defects such as streaks and pickups. The present invention has been devised in order to solve such a problem, and the shape of the edge tip at the bearing introduction angle has a significant effect on the surface texture of the product, and the shape of the edge tip is specified. By doing so, it is an object to produce a high-quality aluminum extruded profile having a stable surface property with a high yield.

[0006]

In order to achieve the object, an aluminum extrusion die of the present invention is an extrusion die for extruding an aluminum material into a target shape by hot extrusion, which corresponds to the target shape. A bearing surface that defines a slit having the above-mentioned shape is formed, and R = 0.3 to at the edge portion between the bearing surface and the die surface.
It is characterized by having a radius of 1.5 mm. The die surface around the slit is preferably formed at right angles to the bearing surface. If necessary, a hard surface layer is formed on the bearing surface and the die surface by nitriding treatment such as salt bath nitriding. Specifically, the extrusion die is of a split type as shown in FIG. 2A, and each of the die members 1 and 2 has a fixing screw hole 3 ,.
4 are formed. When the die members 1 and 2 are assembled with a fixing screw (not shown) inserted through the screw holes 3 and 4, a die having a slit 5 is assembled as shown in FIG. 2B. The slit 5 is defined by the bearing surfaces 6 and 6 as shown in FIG.

The aluminum material flows like a metal flow indicated by an arrow, passes from the bearing edge portion 7 through the slit 5, and is extruded into a predetermined shape. As described in the above-mentioned “Plasticity and processing”, when the bearing introduction angle α is 90 degrees, the pressure required for extrusion is the smallest. In such an extrusion die, in the present invention, the radius of the edge portion 7 is set to a range of R = 0.3 to 1.5 mm. The aluminum extruded profile produced using this extrusion die has a surface roughness of R _max ≦ 4.
It has an excellent surface quality with a gloss of 35% or more at μm, and is used for housing such as aluminum curtain walls, building construction materials, and aluminum buildings where landscape is required.

[0008]

[Function] Aluminum material to which extrusion pressure is applied is
It is pressed against the die surface by the metal flow shown by the arrow in FIG. In the portion that hits the slit 5, the aluminum material passes through the slit 5 in the extrusion flow 8 in a shape corresponding to the slit shape. In the portion that contacts the die surface 9, the aluminum material pressed against the die surface 9 becomes a creeping flow 10 and moves toward the slit 5. In order to reduce the friction between the creeping flow 10 and the die surface 9 and to avoid an increase in extrusion pressure, the bearing introduction angle α = 90 as described in “Plasticity and processing” above.
The degree is optimal. However, at the edge portion 7 finished to α = 90 degrees, since the creeping flow 10 is changed to the extrusion flow 8, stress concentrates and defects such as chipping and abrasion are likely to occur at the edge portion. In this respect, in the present invention, the radius of the edge portion 7 is set to a range of R = 0.3 to 1.5 mm, thereby suppressing the loss and wear of the edge portion without increasing the extrusion pressure. . When the radius of the edge portion 7 is set to R = 0.3 to 1.5 mm, the nitride layer formed on the surface of the die has a particular edge portion 7 as shown in FIG.
The white layer does not grow thick and is formed with a uniform thickness. Therefore, as described with reference to FIG. 1, exfoliation of the hard and brittle white layer is avoided, and there is no streak or pickup due to the exfoliated white layer, and an extruded profile with improved surface gloss is manufactured. . Further, since it is not necessary to sharply finish the corner portion, the polishing finish itself of the bearing surface becomes easy.

The extrusion die according to the present invention is effective even when the nitriding treatment is not performed, but exhibits a particularly remarkable effect when the hard surface layer is formed by the nitriding treatment. That is, in order to form a nitride layer having a uniform thickness, the radius of the edge portion 7 needs to be 0.3 mm or more. In the radius less than 0.3 mm, the effect of sharp corners that accelerate the nitriding reaction appears strongly,
A thick white layer is formed on the edge portion 7. But 1.5m
If a radius of more than m is attached to the edge portion 7, the influence of the creeping flow becomes strong and the extrusion pressure rises. In addition, the outflow rate of the aluminum material is reduced, and the productivity is reduced. Further, it is needless to say that the method can be applied to the case where a BN layer or the like is formed on the nitride layer. The edge portion 7
The addition of the radius to the point is also reported in "Plasticity and Working", Vol. 23, No. 256 (1982), page 437. However, the report shows that R = 0 mm and R =
As a result of comparing the performance of processing dies having an edge portion of 1.5 mm and R = 3 mm, R≈0 from the viewpoint of reducing the extrusion pressure.
Only mm is evaluated to be the most effective, and the shape of the edge portion is not devised in order to improve the surface quality of the extruded shape member.

[0010]

【Example】

Example 1: Tool steel SKD61 was used as a die material, and after heat treatment to HRC48, R = 0.5 mm
Bearing surface having a rounded edge portion (example of the present invention) and deburring the edge portion after polishing to R
A die having a bearing surface (Comparative Example 1) finished to = 0 mm was prepared. As a conventional die, a die (Comparative Example 2) prepared only by machining without controlling the shape of the edge portion was prepared. In each die, the shape of the slit was set to 40 mm in length and 3 mm in width, and the length of the bearing surface was set to 5 mm.

The edge portion of each die is measured by a shape measuring instrument CONT.
The shape of the edge portion was measured by RACER. In Comparative Example 1, as shown in FIG. 4B, the edge portion was substantially R = 0 mm, and both the bearing surface 6 and the die surface 9 were flat surfaces. As shown in FIG. 4C, the edge portion of the conventional product has a sharp edge tip, but some irregularities are seen on the die surface 9.
On the other hand, in the example of the present invention, as shown in FIG. 4A, the edge portion was provided with a radius R of 0.5 mm, and both the bearing surface 6 and the die surface 9 were flat surfaces. An aluminum billet was hot extruded under the following conditions using each die. Extruded material: 6063 Extrusion speed: 40m /
Minute billet temperature: 480 ° C Extrusion ratio: 65.5 Die temperature: 450 ° C

With respect to each of the obtained extruded shape members, the glossiness was measured at an incident angle of 60 degrees using a digital variable angle glossmeter.
As shown in FIG. 5 showing the measurement result, in the conventional die (Comparative Example 2) in which the shape of the edge portion is not controlled, the glossiness of the extruded profile obtained at the beginning of extrusion is as low as about 35%, Moreover, as the extrusion continued, the gloss decreased to 30% or less. In the die with deburring the edge portion (Comparative Example 1), the glossiness of the extruded profile obtained at the beginning of extrusion was 40%.
However, the glossiness decreased as the extrusion length increased. On the other hand, according to the present invention, the die having R at the edge portion (Example of the present invention) has a gloss level of about 40% even when the extrusion length reaches 50 m, and an extruded profile having an extremely high surface gloss is obtained. Had been obtained. From this, it was confirmed that R attached to the edge portion was effective in improving the surface gloss.

Example 2: The same tool steel SKD6 as in Example 1
The die for extrusion processing was produced in 1 and various corners were added to the corners of the edge portion. Then, salt bath nitriding was performed with a nitriding bath composed of cyanide salts such as KCN and NaCN and cyanates such as KCNO and NaCNO to form a hard surface layer on the bearing surface and the die surface around the slit. The hard surface layer had a substantially uniform thickness (average thickness 5 μm) without thick growth of the white layer at the edge portion where R ≧ 0.3 mm. Also in this case, the shape of the slit was set to 40 mm in length and 3 mm in width, and the length of the bearing surface was set to 5 mm. Using this die, aluminum alloy 6063 was hot extruded under the same conditions as in Example 1, and the surface gloss of the extruded profile when the extruded length reached 50 m was measured. When the surface gloss was sorted by the rounded edges, the relationship shown in FIG. 6 was established between the two. As is clear from this result, the die of Comparative Example 1 (R = 0 m
Compared with m), the surface gloss was improved by adding R to the edge portion, and the surface gloss was highest at R = 0.5 mm. On the other hand, when R exceeds 0.5 mm, the surface gloss begins to decrease, but until R = 1.5 mm, the extrusion pressure does not rise excessively, and an extruded profile having excellent surface gloss was obtained. .

[0014]

As described above, in the present invention, a bearing surface having an edge portion of R = 0.3 to 1.5 mm is formed on an extrusion die used for hot extrusion of an aluminum material. are doing. R = 0.3-1.5m
The edge portion of m does not cause an increase in extrusion pressure, and also prevents wear and defects due to stress concentrated on the edge portion from occurring in the edge portion. The R of the edge portion is also effective in making the surface hard layer formed by the nitriding treatment on the surface of the die uniform in thickness. Therefore, the surface layer separated from the die body due to wear or damage does not get caught in the extruded material, and an extruded shape material having excellent surface properties can be obtained. The extruded aluminum profiles produced in this way are used as high quality materials for a wide range of applications such as houses such as aluminum curtain walls, building construction materials and aluminum buildings where landscape is required by utilizing their excellent surface properties. used.

[Brief description of drawings]

FIG. 1 is a diagram showing that a hard surface layer formed on the surface of a conventional extrusion die has a thick edge portion.

FIG. 2 is an exploded view (a), an assembly view (b), and an enlarged cross-sectional view (c) around a slit of a split-type extrusion die.

FIG. 3 is a diagram showing that the surface hard layer formed on the surface of the processing die having the rounded edges according to the present invention has a uniform thickness.

FIG. 4 is a cross-sectional view of the extrusion die (a) of the present invention having a rounded edge portion, the extrusion die (b) of Comparative Example 1 in which R of the edge portion is 0 mm, and the shape of the edge portion are controlled. A graph in which the edge shape is measured for each of the extrusion dies (c) of Comparative Example 2 not shown

FIG. 5 is a graph showing that when the aluminum material is extruded using each die, the surface gloss of the extruded shape material changes according to the extruded length.

FIG. 6 is an extrusion length of 50 m when an aluminum material is extruded using a nitriding extrusion die.
Graph showing the effect of R at the edge on the surface gloss of the extruded profile when reaching

[Explanation of symbols]

1, 2: Die member 3, 4: Screw hole 5: Slit 6: Bearing surface 7: Edge part of bearing surface 8: Extrusion flow
9: Die surface 10: Creeping flow α: Bearing introduction angle R: Rounded edge

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Reiko Takazawa 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture

Claims (4)

[Claims] 1. An extrusion die for extruding an aluminum material into a target shape by hot extrusion, wherein a bearing surface defining a slit having a shape corresponding to the target shape is formed, and the bearing surface and the die surface are formed. An aluminum extrusion die with R = 0.3 to 1.5 mm rounded on the edge part between them. 2. The aluminum extrusion die according to claim 1, wherein the die surface around the slit is formed at a right angle to the bearing surface. 3. An aluminum extruding die having a surface hard layer formed by nitriding treatment on the bearing surface and the die surface according to claim 1. 4. Obtained by hot extrusion using the die for aluminum extrusion according to claim 1,
An extruded shape material having a surface roughness R _max ≦ 4 μm and a glossiness of 35% or more and excellent surface properties.