Method of forming a cup shaped aluminum magnesium alloy article by rotary extrusion

Abstract

Provided is a method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion, including the following steps. (1) Blanking. (2) Performing rotary extrusion: placing a cylindrical billet into a concave die cavity, wherein a peripheral wall of the cavity of the concave die is provided with at least two symmetrical axial grooves; inserting a convex die into the concave die cavity, wherein an end of a working region of the convex die is provided with a groove of a trapezoidal cross section; subjecting the convex die to forward extrusion and heating, and simultaneously rotating and heating the concave die, wherein an integral torque is formed during the extrusion process of the convex die by using the cylindrical billet inside the groove having a trapezoidal cross section, and wherein a synchronized rotation with the concave die is achieved by using a metallic billet that flows into the axial groove. (3) Demolding.

Claims

1. A method of forming a cup-shaped aluminum-magnesium-alloy article, wherein the method comprises: (1) providing a segment of a cylindrical billet; and (2) performing rotary extrusion by: placing the cylindrical billet into a cavity of a concave die of a special mold, wherein the special mold is configured for performing the rotary extrusion to form the cup-shaped aluminum-magnesium-alloy article, a peripheral wall of the cavity of the concave die is provided with at least two symmetrical axial grooves, and a clamping part of the concave die is made to have a hollow cavity in an interior of the clamping part, inserting a convex die of the special mold into the cavity of the concave die, wherein an end of a working region of the convex die is provided with a groove of a trapezoidal cross section, and the convex die is made to have a hollow space in an interior of the convex die, with the hollow space having a constant cross-sectional area, and performing forward extrusion and heating on the convex die and simultaneously rotating and heating the concave die, wherein an integral torque is formed during the forward extrusion of the convex die, by using the cylindrical billet inside the groove of the trapezoidal cross section, and the cylindrical billet, which flows into the axial grooves during the extrusion, is rotated synchronously with the concave die; and (3) demolding, wherein the cup-shaped light-weight alloy article is taken out from the cavity of the concave die after the rotary extrusion.

2. The method according to claim 1, wherein the heating of the concave die is performed by an electric heater placed in the cavity of the concave die.

3. The method according to claim 1, wherein a bottom of the cavity of the concave die that is configured for placement of the billet is made into a form of an insert block, a middle of the insert block is provided with a bore for welding a thermocouple wire, and the thermocouple wire is placed together with the insert block at the bottom of the cavity of the concave die.

4. The method according to claim 1, wherein the at least two symmetrical axial grooves includes six symmetrical axial grooves.

5. The method according to claim 1, wherein the heating of the convex die is performed by an electric heater placed in the hollow space of the convex die.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view of a convex die of the present disclosure;

(2) FIG. 2 is a view of the direction A in FIG. 1;

(3) FIG. 3 is a view of the direction B in FIG. 1;

(4) FIG. 4 is a view of the direction C in FIG. 3;

(5) FIG. 5 is a sectional view of a concave die of the present disclosure;

(6) FIG. 6 is a sectional view of an insert block of the concave die of the present disclosure;

(7) FIG. 7 is a view of the direction D in FIG. 5;

(8) FIG. 8 is a view of the direction E in FIG. 5;

(9) FIG. 9 is a schematic view I of a method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion according to the present disclosure;

(10) FIG. 10 is a schematic view II of the method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion according to the present disclosure;

(11) FIG. 11 is a schematic view III of the method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion according to the present disclosure;

(12) FIG. 12 is a schematic view IV of the method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion according to the present disclosure;

(13) FIG. 13 is a schematic view V of the method of forming a cup-shaped aluminum-magnesium-alloy article by rotary extrusion according to the present disclosure; and

(14) FIG. 14 is a sectional view of a cup-shaped aluminum-magnesium-alloy article according to the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(15) The present disclosure will be further described below by referring to the accompanying drawings and the embodiments.

(16) As shown in FIGS. 1-8 and FIG. 9, provided is a special mold 1 for forming of an aluminum-magnesium alloy by rotary extrusion, including a convex die 2 and a concave die 3. An end 22 of a working region 21 of the convex die is provided with a groove of a trapezoidal cross section 23, so as to facilitate the formation of a torque for the entire metal during the shape-forming process by using the metal in the groove of a trapezoidal cross section 23. In order to ensure the heating efficiency of the billet and the service life of the convex die, the interior of the convex die 2 is made into a hollow space 24 with a constant cross-sectional area. The peripheral wall 31 of cavity 30 of the concave die is provided thereon with six symmetrical axial grooves 32. While the convex die 2 is extruding in forward direction, the billet and the concave die 3 undergo synchronized rotation by using the metal that flows into the axial groove 32 during the extrusion. In order to ensure a homogeneous heating of the billet, the interior of a clamping part 34 of the concave die is also made into a hollow cavity 33. In addition, in order to ensure the convenience for the welding of a thermocouple wire and to prevent it from falling off during the deformation, the bottom 35 of the cavity of the concave die 3, which is used for the placement of the billet, is made into a form of an insert block 36. The middle of the insert block 36 is provided therein with a bore 37 for welding a thermocouple wire (not shown in the figures). The bore is placed together with the insert block 36 into the bottom 35 of the cavity of the concave die 3, which facilitates the operations.

(17) The special mold for forming an aluminum-magnesium alloy through rotary extrusion according to the present disclosure remarkably reduces an axial extrusion force, such that the deformation of the article formed thereof is more uniform. The mold can be applied to a twisting unit of Gleeble 3500 (a thermal simulation testing machine) for the shape-forming through the rotary extrusion. This lays a foundation for physical simulation of the rotary process parameters. In the twisting test, one end of the Gleeble 3500 specimen is prohibited from moving in the circumferential direction, and the other end is driven to rotate by a servo-controlled hydraulic device. As a result, the temperature gradient along the entire length of the scale distance of the twisted specimen is unevenly distributed in the axial direction, which would remarkably aggravate the degree of inhomogeneous strain. Through the sensing of a temperature measuring element, the system exerts dynamic program control over the loading and temperature of the twisted specimen. Therefore, through reasonable design of the structure and size of the special mold for rotary extrusion forming of an aluminum-magnesium-alloy article, and through effective control of temperature distribution, the heating for an internal specimen tends to become uniform, such that an efficient and uniform heating for the specimen is achieved, and a dynamic testing for shape-forming parameters of the twisting test is achieved.

(18) If an electric heater for the convex die (not shown in the figures) is placed in the hollow space 24 of the convex die 2 and an electric heater for the concave die (not shown in the figures) is placed in the hollow cavity 33 of the concave die 3, the present disclosure may also be used in an ordinary extruder.

(19) As shown in FIGS. 9-14, FIG. 3, FIG. 4 and FIG. 7, a method for forming a cup-shaped aluminum-magnesium-alloy article by using the special mold 1 configured for forming an aluminum-magnesium-alloy article through rotary extrusion according to the present disclosure is as follows:

(20) (1) blanking: wherein a cylindrical billet 4 is taken;

(21) (2) performing rotary extrusion: wherein the cylindrical billet 4 is placed into a concave die cavity 30. A convex die 2 is inserted into the concave die cavity 30 for forward extrusion and heating, and at the same time the concave die 3 is rotated and heated, so as to achieve an effect of simultaneous rotation and extrusion. During the extrusion of the convex die 2, an integral torque is generated by using the cylindrical billet 4 inside the groove of a trapezoidal cross section 23. An axial extrusion force is significantly reduced by the rotation of the concave die 3, which promotes a uniform flow of the billet and improves the uniformity of the deformation. This significantly reduces the discrepancy between the axial and circumferential properties of the article formed and improves the shape-forming property. Moreover, this greatly reduces the frictional force, and improves the utilization of the material. Further, the metallic billet that flows into the axial groove 32 during the extrusion process is able to rotate synchronously with the concave die 3. The large plastic deformation process with simultaneous rotation and extrusion is beneficial to the improvement of the mechanical property of the workpiece formed thereof;

(22) (3) demolding: a cup-shaped light-weight alloy article 5 is taken out from the concave die cavity 30 after the rotary extrusion.

(23) Compared with the traditional direct extrusion, the method of shape-forming by rotary extrusion according to the present disclosure is associated with the following features. (1) After applying a twist action by the concave die, deformation and flow may also occur for materials at bottom and corners, the range of blind spot is remarkably reduced or even eliminated, which improves the utilization of the material. (2) After applying a torque to the concave die, the stress condition during the extrusion is changed. A strong shear deformation would have an important impact on the improvement of the microscopic texture. (3) In addition to flowing along a loaded axial direction, the extruded metal also has a tendency of being twisted and deformed along a circumferential direction. This, to a great extent, improves the degree of plastic deformation of the metal. (4) Under the same condition of extruding devices, the processing and manufacturing of an irregular cross section can be achieved; under the same condition of structures, the shape-forming load and the tonnage of the device can be reduced, thereby achieving the object of small device with a big capability. By using these features of rotary extrusion in the present disclosure and by using the generation of tangential shear deformation, the normal pressure is decreased, the texture density is improved, the plastic deformation is increased, and the texture morphology of the material is improved. As a result, the deformation of the extruded article is more uniform. In another aspect, an axial extrusion force is significantly reduced, which makes the deformation of the article formed more uniform and greatly improves the mechanical property of the workpiece formed thereof. It improves the utilization of the material, and remarkable economic benefits can be achieved through promotion in the forging industry.