JP2014151365A - INDIRECT EXTRUDING METHOD OF Al ALLOY MATERIAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an indirect extruding method of an Al alloy material, capable of easily extracting an Al alloy material with high hardness, by reducing necessary extrusion pressure when starting extrusion.SOLUTION: An indirect extruding method of an Al alloy material, extrudes an Al alloy material 1 from a space between an inner periphery of a die 121 and an outer periphery of a mandrel 150 to mold a hollow body 10, by using an indirect extruder 100 equipped with the annular die 121 and the rod-shaped mandrel 150. The mandrel 150 has a body portion 151; and a small-diameter portion 152 provided on one end side of the body portion 151 and having an outer diameter smaller than the body portion 151. The extrusion is started from the space between the die 121 and the small-diameter portion 152, and then, the hollow body 10 is molded between the die 121 and the body portion 151.

Description

  The present invention relates to an indirect extrusion method for an Al alloy material in which a cylindrical Al alloy material mainly composed of an Al alloy is formed into a hollow body by indirect extrusion. In particular, the present invention relates to an indirect extrusion method for an Al alloy material that can effectively extrude even a high hardness Al alloy material by effectively reducing the required extrusion pressure of the Al alloy at the start of extrusion.

  A hollow body such as a cylinder or tube made of aluminum (hereinafter referred to as Al) or an alloy thereof is generally manufactured by drawing or extrusion. As an apparatus used for extrusion, for example, there is one shown in Patent Document 1.

  The extruder disclosed in Patent Document 1 includes a container having both ends open, a die that is disposed at one end of the container to define the outer diameter of the hollow body, an annular loose dummy that is disposed at the other end of the container, and a die And a mandrel disposed between the loose dummy. The mandrel is composed of a bearing that defines the inner diameter of the hollow body, a tapered surface that expands from the bearing toward the loose dummy side, and a large-diameter portion having a uniform outer diameter that is formed continuously from the tapered surface. Is done. In this extruder, a part of the bearing is inserted and placed in the die so that the die is placed near the boundary between the bearing of the mandrel and the tapered surface, and the large diameter part of the mandrel is slidably inserted into the hollow portion of the loose dummy. Be placed. Then, with the mandrel inserted into the billet (workpiece), the die and the mandrel are moved together in the direction of the loose dummy so that the distance between the die and the bearing is relatively Since it is constant regardless of the movement, an extruded shape (hollow body) having a uniform thickness is formed by indirect extrusion in which the billet is extruded from a die.

JP 09-201618 A

  In recent years, hollow bodies with higher hardness have been desired, and it is conceivable to increase the content of additive elements that contribute to higher hardness in Al alloys. However, Al alloys with a high content of the above additive elements and high hardness have a high deformation (extrusion) resistance of the alloy itself (inferior in plastic deformability), that is, tend to have a high extrusion pressure required for plastic deformation. is there. For example, if an extruder with a high extrusion pressure is used, it is easy to extrude even a workpiece made of such an Al alloy, but the equipment tends to be large. On the other hand, if an extruder with a low extrusion pressure is used, the workpiece may not be able to form a molded body having a uniform thickness, or the workpiece may not be extruded in the first place. In the conventional extruder, as described above, since the workpiece is extruded from the die with a constant distance between the die and the bearing, the extrusion ratio at the start of extrusion and the extrusion ratio thereafter are the same, In the case of a workpiece having a high deformation resistance, there is a possibility that the workpiece cannot be extruded.

  The present invention has been made in view of the above circumstances, and one of its purposes is indirect extrusion of an Al alloy material that can easily extrude a high hardness Al alloy material by reducing the required extrusion pressure at the start of extrusion. It is to provide a method.

  The inventors of the present invention studied reducing the required extrusion pressure at the start of extrusion in a high hardness Al alloy material. As a result, a mandrel having a small outer diameter and a large outer diameter in the axial direction is used, and at the beginning of extrusion (at the start), the mandrel has a small diameter, and after that, the mandrel has a large diameter. It was found that by extruding, a high hardness Al alloy material can be easily extruded from a die at the start of extrusion, and a molded product having a desired inner diameter can be obtained. Based on this finding, the present invention is defined below.

  The indirect extrusion method of the Al alloy material of the present invention uses an indirect extruder including an annular die and a rod-shaped mandrel, and extrudes the Al alloy material from between the inner periphery of the die and the outer periphery of the mandrel to form a hollow body. This is a molding method. The mandrel includes a main body portion and a small diameter portion that is provided on one end side of the main body portion and has an outer diameter smaller than that of the main body portion. Then, the extrusion is started from between the die and the small diameter portion, and thereafter, the hollow body is formed between the die and the main body portion.

  According to the above method, the Al alloy material can be easily extruded. By starting extrusion at the small diameter portion, the extrusion ratio can be made smaller than when extrusion is started at the main body portion. For this reason, the necessary extrusion pressure at the start of extrusion, which requires a relatively large extrusion pressure as compared with the middle of extrusion, can be made smaller than the necessary extrusion pressure when starting extrusion at the main body portion.

  As one form of the indirect extrusion method of the Al alloy material of the present invention, the extrusion ratio at the small diameter portion is 18 or less.

  According to the said structure, since the extrusion ratio at the time of an extrusion start is small, the required extrusion pressure at the time of an extrusion start can be made low.

  As one form of the indirect extrusion method of the Al alloy material of the present invention, the mandrel includes a sloped portion formed by connecting a main body portion and a small diameter portion and having an inclined surface whose diameter decreases from the main body portion to the small diameter portion. In this case, when the angle formed by the extended surface of the inclined surface of the mandrel and the outer peripheral surface of the main body portion is the inclined angle of the inclined surface, the inclined angle is preferably 10 ° or more and 30 ° or less.

  According to the said structure, when making the said inclination-angle 10 degrees or more and making the extrusion ratio in a small diameter part into a desired extrusion ratio, the length of the axial direction in an inclination part does not become long. By setting the inclination angle to 30 ° or less, a rapid increase in the extrusion ratio can be suppressed from the small diameter portion to the main body portion, and smooth extrusion can be performed from the start of extrusion to the subsequent time.

  The indirect extrusion method of an Al alloy material of the present invention can easily extrude a high hardness Al alloy material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the extrusion process of the Al alloy material using the indirect extruder used in embodiment, and an indirect extruder, (A) shows the state before extrusion of Al alloy material, (B) is Al. The initial state of extrusion of the alloy material is shown, and (C) shows the state during the extrusion of the Al alloy material. It is a longitudinal cross-sectional view which shows the outline of the mandrel with which the indirect extruder used in embodiment is equipped.

  Embodiments of the present invention will be described below.

《Indirect extrusion method of Al alloy material》
The indirect extrusion method of the Al alloy material of the present invention is a method of forming a hollow body by extruding an Al alloy material using an indirect extruder equipped with a die and a mandrel. The main feature of the indirect extrusion method of the Al alloy material of the present invention is that a mandrel having a portion with a small outer diameter and a large portion in the axial direction is used. After that, the mandrel has a large diameter to be extruded. First, an example of an indirect extruder used for indirect extrusion will be described with reference to FIGS. 1 and 2, and then an extrusion method for extruding an Al alloy material using the indirect extruder will be described.

(Indirect extruder)
The indirect extruder 100 includes a container 110, a die stem 120 having a die 121 and a stem 122, a ram 130, a dummy block 140, and a mandrel 150.

  The container 110 is a member that accommodates a workpiece (described later) and pressurizes the workpiece, and is configured in a cylindrical shape that is open at both ends. An annular die stem 120 in contact with the inner peripheral surface of the container 110 is disposed on one end side (left side in FIG. 1) of the container 110. The die stem 120 includes an annular die 121 that defines the outer diameter of a molded product that is formed by extrusion, and a stem 122 that supports the die 121. On the other hand, a hollow ram 130 that is in contact with the end surface of the container 110 is provided on the other end side of the container 110. An annular dummy block 140 that is in contact with the inner peripheral surface of the container 110 is brought into contact with the surface of the ram 130 that faces the die 121. At the center of the ram 130 and the dummy block 140, a rod-like (columnar) mandrel 150 is inserted and fixed integrally. Thereby, the mandrel 150 is positioned with respect to the container 110.

  In the indirect extruder 100, the container 110 is fixed to a main body device (not shown), and the die stem 120 moves from one end side of the container 110 to the other end side. As the die stem 120 moves toward the other end of the container 110, pressure is applied to the workpiece in the container 110 to push the workpiece from between the inner periphery of the die 121 and the outer periphery of the mandrel 150. The die stem may be fixed and the container may be moved to the die stem side by a ram. In that case, as the ram and container move, the dummy block and mandrel also move together with the container toward the die stem.

[Mandrel]
The mandrel 150 is a rod-like body that defines the inner diameter of a molded product that is inserted into a workpiece and is extruded and molded from the die 121 by moving the die stem 120 toward the other end of the container 110. The mandrel 150 is small and a small main body 151 in diameter than the inner diameter _{d i} of the die 121, a smaller diameter than the outer diameter _{d b} of the main body portion 151 at the tip of the die 121 side of the main body portion 151 (container 110 one end side) Unit 152.

The main body 151 defines the inner diameter of the molded product. Outer diameter d _b of the main body portion 151 may be suitably selected so that the desired inner diameter of the molded article. On the other hand, the small diameter portion 152 reduces the extrusion ratio at the start of extrusion when the workpiece is extruded by the small diameter portion 152. Size to the outer diameter d _b of the body portion 151 of the outer diameter d _s of the small-diameter portion 152 is small enough extrusion ratio than extrusion ratio of the molded article, the degree of reducing the required extrusion pressure at the start of extrusion To do. Specifically, the extrusion ratio at the small diameter part is preferably 18 or less. By doing so, the required extrusion pressure at the start of extrusion can be made sufficiently small. The extrusion ratio is a value obtained by dividing the cross-sectional area of the inner diameter of the container 110 by the cross-sectional area of the molded product determined by the inner diameter d _{i of the} die 121 and the outer diameter d _s of the small diameter portion 152. This extrusion ratio is particularly preferably 12 or more. On the other hand, the upper limit of the difference between the extrusion ratio at the small diameter portion 152 and the extrusion ratio at the main body portion 151 is about 15. If it does so, it can extrude smoothly, suppressing the rapid change of extrusion ratio at the time of extrusion start, and the middle of extrusion.

  The mandrel 150 preferably has an inclined portion 153 that connects the main body portion 151 and the small diameter portion 152. The inclined portion 153 is configured by an inclined surface with an outer diameter narrowing from the main body portion 151 toward the small diameter portion 152 side. The inclined portion 153 facilitates extrusion of the workpiece when the die 121 (die stem 120) moves from the small diameter portion 152 toward the main body 151 during extrusion. In particular, the inclination angle α of the inclined portion 153 is preferably set to 10 ° to 30 ° (FIG. 2). The inclination angle α is an angle formed by the outer peripheral surface of the main body 151 and the extended surface of the inclined surface of the inclined portion 153. By setting the inclination angle α of the inclined portion 153 to 10 ° or more, the axial length of the inclined portion 153 does not increase when the extrusion ratio at the small diameter portion 152 is set to a desired extrusion ratio. By setting the inclination angle α of the inclined portion 153 to 30 ° or less, a rapid increase in the extrusion ratio from the small diameter portion 152 to the main body portion 151 can be suppressed, and smooth extrusion can be performed from the start of extrusion to the subsequent time.

〔Manufacturing process〕
The indirect extrusion method of the Al alloy material of the present invention using such an indirect extruder 100 will be described. Specifically, it includes a preparation step for preparing a cylindrical Al alloy material, a loading step for loading the Al alloy material into the indirect extruder 100, and an extrusion step for extruding the Al alloy material to form a hollow body.

[Preparation process]
The Al alloy material 1 prepared in the preparation process has an Al alloy as a main component. Here, an Al alloy as a main component means that an additive element is contained and the balance is only an Al alloy consisting of Al and inevitable impurities, and a case where hard particles are contained and the balance is made of the Al alloy. Including. Examples of the additive element include at least one of Si, Fe, Mn, Mg, and Cu. Examples of the hard particles include Al ₂ O ₃ . In addition, as a solid lubricant, graphite, MoS ₂ , boron nitride, and the like can be included.

  For example, the Al alloy material 1 may be formed by using CIP (cold isostatic pressing). By this molding, the shape of the Al alloy material 1 is made the final molded product shape (cylindrical).

[Loading process]
In the filling process, the Al alloy material 1 is loaded into the container 110. Specifically, the mandrel 150 is inserted into the Al alloy material 1 in the container 110. Then, one end surface of the Al alloy material 1 is brought into contact with the dummy block 140, and the other end surface is brought into contact with the die 121 (FIG. 1A). At this time, the position of the contact surface between the Al alloy material 1 and the die 121 is positioned closer to the small diameter portion 152 than the boundary between the small diameter portion 152 and the inclined portion 153 of the mandrel. If it does so, since the space | interval of the die 121 inner periphery and the outer periphery of the mandrel 150 can be ensured widely, it will become easy to start extrusion. In particular, the closer the position of the contact surface is to the boundary, the smaller the thick part (FIG. 1B) formed at the tip when the Al alloy material 1 is extruded. Here, the position of the abutting surface is arranged slightly closer to the small diameter portion 152 than the boundary.

[Extrusion process]
In the extrusion process, the die stem 120 is moved to the other end side of the container 110 to extrude the Al alloy material 1 from between the inner periphery of the die 121 and the outer periphery of the mandrel 150 to form the Al alloy hollow body 10. Specifically, as described above, extrusion is started in the state where the position of the contact surface between the Al alloy material 1 and the die 121 is arranged near the boundary between the small diameter portion 152 and the inclined portion 153 (FIG. 1A). To do. At the beginning extrusion, as shown in FIG. 1 (B), first, an inner diameter corresponding to the outer diameter d _s of the small-diameter portion 152, the thick portion 1t having an outer diameter corresponding to the inner diameter d _i of the die 121 Molded. By pushing it continues as it is, as shown in FIG. 1 (C), Al alloy hollow body 10 having an inner diameter corresponding to an outer diameter d _b of the main body portion 151 and an outer diameter corresponding to the inner diameter d _i of the die 121 Is formed.

  The extrusion pressure of the Al alloy material 1 in this extrusion process is 340 MPa or less, preferably 300 MPa or less. By setting the mandrel 150 as the above-described configuration and starting extrusion at the small-diameter portion 152 of the mandrel 150, even when the extrusion pressure is as low as 340 MPa or less, the high hardness Al alloy material 1 can be easily extruded.

The extrusion speed is 2 mm / s to 5 mm / s, the extrusion temperature is 480 to 540 ° C., the extrusion ratio at the start of extrusion (the cross-sectional area A of the thick part 1t relative to the cross-sectional area A ₀ of the Al alloy material 1) ₁ ratio A ₀ / A ₁ ) is preferably 12-18. Within this extrusion speed range, productivity can be improved while reducing the occurrence of cracks and surface defects. The extrusion speed here refers to the speed of the die stem 120 of the extruder, and the extrusion speed of the molded product is represented by the product of the speed of the die stem 120 and the extrusion ratio. The extrusion speed of a specific molded product is preferably 24 mm / s to 90 mm / s.

[Other processes]
The thick part 1t formed at the start of extrusion remains in the tip of the Al alloy hollow body 10 at the end of the extrusion process. This thick part 1t is originally an unnecessary part and is cut. In addition, the Al alloy hollow body 10 may be appropriately subjected to cutting, machining, finishing, and the like. Thereby, the Al alloy hollow body 10 having a desired dimensional accuracy can be obtained.

<Effect>
According to the indirect extrusion method of the Al alloy material described above, the extrusion ratio can be reduced by starting extrusion at the small diameter portion as compared with the case of starting extrusion at the main body portion. Therefore, the required extrusion pressure at the start of extrusion, which requires a relatively large extrusion pressure as compared to the middle of extrusion, can be made smaller than the necessary extrusion pressure when starting extrusion at the main body. Therefore, it is possible to easily extrude a high hardness Al alloy material and form an Al alloy hollow body. That is, it is not necessary to have a large facility as an indirect extruder.

《Test example》
The Al alloy material 1 was extruded using the indirect extruder 100 described with reference to FIG. In this example, a mandrel 150 having an outer diameter of the main body portion 151 of 62 mm and an outer diameter of the small diameter portion 152 of 49 mm is used. The inclination angle α of the inclined part 153 was 20 °. The inner diameter di of the die 121 was 72 mm.

  First, by air atomization method, Si is contained by 17% by mass, Fe by 5% by mass, Cu by 3.5% by mass, Mg by 1% by mass, and Mn by 0.5% by mass with the balance being Al and inevitable impurities. An Al alloy powder comprising: Next, Al alloy powder was formed into a cylindrical shape by CIP (cold isostatic pressing) to prepare an Al alloy material 1.

  After the Al alloy material 1 is heated in an atmospheric furnace, it is loaded into the container 110 of the indirect extruder 100. In a state where the mandrel 150 is inserted into the center hole of the cylindrical Al alloy material 1 in the container 110, the end surface of the Al alloy material 1 is pressed by the die stem 120 and extruded from the inner periphery of the die 121 and the outer periphery of the mandrel 150. At that time, extrusion was performed assuming that the extrusion pressure of the die 121 was 330 MPa, the extrusion temperature was 480 ° C., the extrusion speed was 3 mm / s, and the extrusion ratio at the start of extrusion was 12.

  As a result, an Al alloy hollow body 10 having a thickness of 10 mm (outer diameter: 72 mm, inner diameter: 62 mm) and a length of 6000 mm was formed. This is because by starting extrusion at the small diameter portion 152, the extrusion ratio can be reduced and the required extrusion pressure at the start of extrusion can be reduced.

  On the other hand, when a mandrel having an outer diameter uniform in the axial direction without a small diameter portion was prepared and the above-described Al alloy material 1 was extruded under the same conditions as described above, extrusion was not possible. This is probably because the extrusion ratio was constant from the start of extrusion and the required extrusion pressure at the start of extrusion could not be reduced.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

  The indirect extrusion method of an Al alloy material of the present invention can be suitably used for molding parts for internal combustion engines such as automobiles and motorcycles. The Al alloy hollow body formed by the indirect extrusion method of the Al alloy material of the present invention can be suitably used for components for internal combustion engines such as automobiles and motorcycles.

DESCRIPTION OF SYMBOLS 100 Indirect extruder 110 Container 120 Die stem 121 Die 122 Stem 130 Ram 140 Dummy block 150 Mandrel 151 Main part 152 Small diameter part 153 Inclined part 1 Al alloy material 10 Al alloy hollow body 1t Thick part

Claims (3)

An indirect extrusion method in which a hollow body is formed by extruding an Al alloy material from between the inner periphery of the die and the outer periphery of the mandrel using an indirect extruder including an annular die and a rod-shaped mandrel,
The mandrel has a main body portion and a small diameter portion that is provided on one end side of the main body portion and has a smaller outer diameter than the main body portion,
The indirect extrusion method of an Al alloy material, in which the extrusion is started between the die and the small diameter portion, and then the hollow body is formed between the die and the main body portion.   The indirect extrusion method for an Al alloy material according to claim 1, wherein an extrusion ratio at the small diameter portion is 18 or less. The mandrel connects the main body part and the small diameter part, and has an inclined part composed of an inclined surface whose diameter decreases from the main body part to the small diameter part,
The inclination angle is 10 ° or more and 30 ° or less when an angle formed by an extended surface of the inclined surface of the mandrel and an outer peripheral surface of the main body portion is an inclination angle of the inclined surface. Indirect extrusion method of Al alloy material.

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