阅读说明：本技术 一种多应变路径下镁合金管材的制备工艺及挤压模具 (Preparation process and extrusion die for magnesium alloy pipe under multiple strain paths ) 是由 杨建雷 张文丛 陈文振 崔国荣 王文珂 于 2020-11-17 设计创作，主要内容包括：本发明提供一种多应变路径下镁合金管材的制备工艺及挤压模具,包括以下步骤：准备棒状的镁合金坯料、高温石墨粉；对镁合金坯料进行热处理,在空气中缓慢冷却；再次进行挤压预热处理；将加热后的镁合金坯料放置在挤压机中,挤压机中挤压凸模和凹模在加热后,将镁合金坯料放置在其中；由于剪切挤压通道为波纹状,可以产生多次挤压变形；对挤压后的镁合金管材进行打磨、清洁。本发明提供的多应变路径下镁合金管材的制备工艺及挤压模具,避免了现有镁合金加工方法存在的挤压织构强烈、拉压不对称性严重以及晶粒细化程度低等技术问题,提高了镁合金的综合力学性能。(The invention provides a preparation process and an extrusion die of a magnesium alloy pipe under multiple strain paths, which comprises the following steps: preparing a bar-shaped magnesium alloy blank and high-temperature graphite powder; carrying out heat treatment on the magnesium alloy blank, and slowly cooling in air; carrying out extrusion preheating treatment again; placing the heated magnesium alloy blank in an extruder, and placing the magnesium alloy blank in the extruder after heating an extrusion convex die and a concave die in the extruder; the shearing and extruding channel is corrugated, so that multiple times of extrusion deformation can be generated; and polishing and cleaning the extruded magnesium alloy pipe. The preparation process and the extrusion die of the magnesium alloy pipe under the multi-strain path provided by the invention avoid the technical problems of strong extrusion texture, serious tension-compression asymmetry, low grain refinement degree and the like in the existing magnesium alloy processing method, and improve the comprehensive mechanical property of the magnesium alloy.)

1. A preparation process of a magnesium alloy pipe under multiple strain paths is characterized by comprising the following steps:

step S1: preparing a bar-shaped magnesium alloy blank and high-temperature graphite powder;

step S2: carrying out heat treatment on the magnesium alloy blank, and slowly cooling in air;

step S3: carrying out extrusion preheating treatment again;

step S4: placing the heated magnesium alloy blank in an extruder, and placing the magnesium alloy blank in the extruder after heating an extrusion convex die and a concave die in the extruder;

the shearing and extruding channel is corrugated, so that multiple times of extrusion deformation can be generated;

step S5: and polishing and cleaning the extruded magnesium alloy pipe.

2. The process for preparing the magnesium alloy pipe under the multi-strain path as claimed in claim 1, wherein in the step S4, the inner side surface of the extrusion die is provided with corrugated shearing extrusion channels.

3. The process for preparing the magnesium alloy tube under the multiple strain paths as claimed in claim 2, wherein in the step S4, the shearing and extruding channel is provided with a plurality of corrugated parts.

4. The process for preparing the magnesium alloy tube under the multi-strain path as claimed in claim 3, wherein in the step S4, a plurality of the corrugated parts can rotate.

5. The process for preparing the magnesium alloy pipe under the multi-strain path according to any one of claims 1 to 4, wherein the grain size of the extruded magnesium alloy pipe is up to 500 nm.

6. The extrusion die for the magnesium alloy pipe under the multi-strain path is characterized by comprising an extrusion male die and an extrusion female die, wherein the extrusion male die and the extrusion female die are both arranged on an extruder, and the extrusion male die extends into the extrusion female die;

the extrusion female die comprises a plurality of external extrusion cylinders and threaded cylinders which are distributed at intervals and connected together, an intermediate extrusion cylinder is arranged between two adjacent threaded cylinders, the external extrusion cylinders and the intermediate extrusion cylinder are provided with smooth inner side surfaces, and the intermediate extrusion cylinder is provided with internal threads;

the outer extrusion barrel, the thread barrel and the middle extrusion barrel are all arranged on a positioning frame, and a driving mechanism for driving the thread barrel to rotate is further arranged on the positioning frame.

7. The extrusion die for the magnesium alloy pipe under the multiple strain paths as claimed in claim 6, wherein a driven gear is arranged on the outer side surface of the threaded cylinder, the centers of the threaded cylinder and the driven gear are consistent, two end surfaces of the threaded cylinder are respectively provided with an embedded part, and the embedded parts are arranged in an open groove on the end surface of the outer extrusion cylinder or the middle extrusion cylinder.

8. The extrusion die for the magnesium alloy pipe under the multiple strain paths as claimed in claim 6, wherein a driven gear is arranged on the outer side surface of the threaded cylinder, the centers of the threaded cylinder and the driven gear are consistent, bearings are respectively arranged at two ends of the threaded cylinder, and the bearings are connected with the end parts of the outer extrusion cylinder or the middle extrusion cylinder.

9. The extrusion die for magnesium alloy pipes under multiple strain paths as claimed in any one of claims 7 to 8, wherein the driving mechanism comprises a driving gear engaged with the driven gear, a rotating shaft passing through the driving gear, and a motor connected to an end of the rotating shaft, and the rotating shaft is disposed on the positioning frame through a supporting seat.

10. The extrusion die for the magnesium alloy pipe under the multi-strain path as claimed in claim 9, wherein the positioning frame comprises a support, an outer clamping cylinder and an inner clamping cylinder which are arranged on the support, and the adjacent ends of the outer extrusion cylinder and the threaded cylinder are respectively clamped on the outer clamping cylinder;

the adjacent end parts of the middle extrusion cylinder and the thread cylinder are respectively clamped on the inner clamping cylinder.

Technical Field

The invention belongs to the technical field of plastic processing of nonferrous metals, and particularly relates to a preparation process and an extrusion die for a magnesium alloy pipe under multiple strain paths.

Background

In recent years, magnesium and magnesium alloys have attracted much attention because of their unique and excellent comprehensive mechanical properties, and are currently the lightest metal structural materials. Because magnesium and magnesium alloys have excellent performance characteristics, for example: the magnesium and magnesium alloy has excellent application prospect, and has been widely applied in the fields of military, aerospace, digital electronic products and the like at present. However, due to crystal structure defects of magnesium and magnesium alloys themselves, such as: magnesium has a close-packed hexagonal structure, few independent sliding systems which can be started are difficult to deform, and the mechanical property at room temperature is poor; in addition, magnesium belongs to active metal, is easy to be oxidized by chemical reaction and has poor corrosion resistance, so that the popularization and application of magnesium and magnesium alloy are greatly limited. Therefore, the application range of the magnesium alloy material can be widened only by producing and processing the magnesium alloy material with good comprehensive mechanical properties.

According to the current research situation, two approaches of alloying and grain refinement are mainly used for improving the comprehensive mechanical property of the magnesium alloy. Alloying refers to adding one or more elements by smelting on the basis of common magnesium alloy, so as to improve the strength and hardness of the magnesium alloy. But because alloy elements or rare earth elements are required to be added in the alloying smelting process, the danger coefficient is high and the cost is high. The severe plastic deformation is a main mode for grain refinement, can overcome the defects of the traditional processing method, enables the grain size of the material to be refined to submicron or even nanometer, and obtains excellent comprehensive mechanical properties, and the common severe plastic deformation mainly comprises the following steps: equal channel angular extrusion, high pressure torsion, cumulative pack rolling and the like. The severe plastic deformation methods have the characteristics, equal channel angular extrusion is the most widely applied method at present, the shape and the size of a sample before and after extrusion are not changed, large plastic deformation can be accumulated by repeated extrusion deformation for many times, but the single extrusion deformation is small; high pressure twisting can produce thin sheet samples with smaller grain size, but the samples are small in size and non-uniform in texture. In summary, many severe plastic deformation processes suffer from a number of technical problems and deficiencies. Therefore, the technical scheme provides a novel severe plastic deformation method.

Disclosure of Invention

The invention aims to provide a preparation process and an extrusion die for a magnesium alloy pipe under multiple strain paths, which solve the technical problems of strong extrusion texture, serious tension-compression asymmetry, low grain refinement degree and the like of the existing magnesium alloy processing method and improve the comprehensive mechanical property of the magnesium alloy.

A preparation process of a magnesium alloy pipe under multiple strain paths is characterized by comprising the following steps:

step S1: preparing a bar-shaped magnesium alloy blank and high-temperature graphite powder;

step S2: carrying out heat treatment on the magnesium alloy blank, and slowly cooling in air;

step S3: carrying out extrusion preheating treatment again;

step S4: placing the heated magnesium alloy blank in an extruder, and placing the magnesium alloy blank in the extruder after heating an extrusion convex die and a concave die in the extruder;

the shearing and extruding channel is corrugated, so that multiple times of extrusion deformation can be generated;

step S5: and polishing and cleaning the extruded magnesium alloy pipe.

In the step S4, a corrugated shearing and extruding channel is provided on the inner side surface of the extruding female die.

In the step S4, the shearing extrusion channel has a plurality of corrugations.

In step S4, a plurality of the corrugations may be rotationally moved.

The grain size of the extruded magnesium alloy pipe reaches 500 nm.

The extrusion die for the magnesium alloy pipe under the multi-strain path comprises an extrusion male die and an extrusion female die, wherein the extrusion male die and the extrusion female die are both arranged on an extruder, and the extrusion male die extends into the extrusion female die;

the extrusion female die comprises a plurality of external extrusion cylinders and threaded cylinders which are distributed at intervals and connected together, an intermediate extrusion cylinder is arranged between two adjacent threaded cylinders, the external extrusion cylinders and the intermediate extrusion cylinder are provided with smooth inner side surfaces, and the intermediate extrusion cylinder is provided with internal threads;

the outer extrusion barrel, the thread barrel and the middle extrusion barrel are all arranged on a positioning frame, and a driving mechanism for driving the thread barrel to rotate is further arranged on the positioning frame.

The outer side face of the threaded cylinder is provided with a driven gear, the centers of the threaded cylinder and the driven gear are consistent, two end faces of the threaded cylinder are respectively provided with an embedding part, and the embedding parts are arranged in an open slot of the end face of the outer extrusion cylinder or the end face of the middle extrusion cylinder.

The outer side surface of the threaded cylinder is provided with a driven gear, the centers of the threaded cylinder and the driven gear are consistent, two ends of the threaded cylinder are respectively provided with a bearing, and the bearings are connected with the end parts of the outer extrusion cylinder or the middle extrusion cylinder.

The driving mechanism comprises a driving gear meshed with the driven gear, a rotating shaft penetrating through the driving gear and a motor connected with the end of the rotating shaft, and the rotating shaft is arranged on the positioning frame through a supporting seat.

The positioning frame comprises a support, an outer clamping cylinder and an inner clamping cylinder, wherein the outer clamping cylinder and the inner clamping cylinder are arranged on the support;

the adjacent end parts of the middle extrusion cylinder and the thread cylinder are respectively clamped on the inner clamping cylinder.

The invention achieves the following remarkable effects:

(1) in a cylindrical extrusion die, the magnesium alloy blank is extruded under a heating state to change the magnesium alloy blank from a rod shape into a tubular shape, then the magnesium alloy pipe passes through a corrugated shearing and extruding channel, and the diameters of the pipe before and after passing through the corrugated shearing and extruding channel are unchanged, so that multiple shearing deformation is generated in the process, the grain structure can be refined, the basal plane texture can be weakened, the comprehensive mechanical property can be improved, and the application range is wider. Finally, the high-performance magnesium alloy pipe with the grain size of about 500nm can be prepared;

(2) the design has a plurality of screw thread section of thick bamboo, and under the effect of external force for screw thread section of thick bamboo is rotatory, helps slowing down because the destructive effect of extrusion force to the magnesium alloy blank, when refining the grain structure, can also accomplish the toughness that guarantees the magnesium alloy blank.

Drawings

FIG. 1 is a view showing the structure of an extrusion die according to the embodiment of the present invention.

Fig. 2 is a structural view of a threaded cylinder in an embodiment of the present invention.

FIG. 3 is a diagram of a positioning frame according to an embodiment of the present invention.

Wherein the reference numerals are: 1. a positioning frame; 1-1, a bracket; 1-2, an outer clamping cylinder; 1-3, an inner clamping cylinder; 2. a driving gear; 2-1, a driven gear; 3. a rotating shaft; 4. a motor; 5. an outer extrusion cylinder; 5-1, an intermediate extrusion cylinder; 6. a threaded barrel; 6-1, an embedding part; 6-2 and internal threads.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present solution is described below by way of specific embodiments.

A preparation process of a magnesium alloy pipe under multiple strain paths is characterized by comprising the following steps:

step S1: preparing a bar-shaped magnesium alloy blank and high-temperature graphite powder;

step S2: carrying out heat treatment on the magnesium alloy blank, and slowly cooling in air;

step S3: carrying out extrusion preheating treatment again;

step S4: placing the heated magnesium alloy blank in an extruder, and placing the magnesium alloy blank in the extruder after heating an extrusion convex die and a concave die in the extruder;

the shearing and extruding channel is corrugated, so that multiple times of extrusion deformation can be generated;

step S5: and polishing and cleaning the extruded magnesium alloy pipe.

In step S4, a corrugated shearing and extruding channel is provided on the inner side surface of the extruding female die.

In step S4, the shear extrusion channel has a plurality of corrugations.

In step S4, the plurality of corrugations may be rotationally moved.

The grain size of the extruded magnesium alloy pipe reaches 500 nm.

Referring to fig. 1, the extrusion die for the magnesium alloy pipe under the multi-strain path comprises an extrusion male die and an extrusion female die, wherein the extrusion male die and the extrusion female die are both arranged on an extruder, and the extrusion male die extends into the extrusion female die;

the extrusion female die comprises a plurality of external extrusion cylinders 5 and threaded cylinders 6 which are distributed at intervals and connected together, an intermediate extrusion cylinder 5-1 is arranged between two adjacent threaded cylinders 6, the external extrusion cylinders 5 and the intermediate extrusion cylinder 5-1 are provided with smooth inner side surfaces, and the intermediate extrusion cylinder 5-1 is provided with an internal thread 6-2;

the outer extrusion cylinder 5, the threaded cylinder 6 and the middle extrusion cylinder 5-1 are all arranged on the positioning frame 1, and the positioning frame 1 is also provided with a driving mechanism for driving the threaded cylinder 6 to rotate.

In the patent, a plurality of threaded cylinders 6 are arranged, so that the magnesium alloy rod can be subjected to multiple deformation treatment, and the refining degree of crystal grains is enhanced.

Referring to fig. 2, a driven gear 2-1 is arranged on the outer side surface of the threaded cylinder 6, the centers of the threaded cylinder 6 and the driven gear 2-1 are consistent, embedded parts 6-1 are respectively arranged on two end surfaces of the threaded cylinder 6, and the embedded parts 6-1 are arranged in open grooves on the end surfaces of the outer extrusion cylinder 5 or the middle extrusion cylinder 5-1.

Preferably, the driven gear 2-1 is arranged on the outer side surface of the threaded cylinder 6, the centers of the threaded cylinder 6 and the driven gear 2-1 are consistent, bearings are respectively arranged at two ends of the threaded cylinder 6, and the bearings are connected with the end parts of the outer extrusion cylinder 5 or the middle extrusion cylinder 5-1.

The driving mechanism comprises a driving gear 2 meshed with the driven gear 2-1, a rotating shaft 3 penetrating through the driving gear 2 and a motor 4 connected with the end part of the rotating shaft 3, and the rotating shaft 3 is arranged on the positioning frame 1 through a supporting seat.

The driving mechanism is arranged, so that the overlarge blocking effect of the raised grains on the magnesium alloy blank can be avoided, the good toughness can be ensured while the grains are refined, the extrusion process is carried out more smoothly, and the resistance is reduced.

Referring to fig. 3, the positioning frame 1 comprises a support 1-1, an outer clamping cylinder 1-2 and an inner clamping cylinder 1-3 which are arranged on the support 1-1, and the adjacent ends of an outer extrusion cylinder 5 and a thread cylinder 6 are respectively clamped on the outer clamping cylinder 1-2;

the adjacent end parts of the middle extrusion cylinder 5-1 and the threaded cylinder 6 are respectively clamped on the inner clamping cylinders 1-3.

Note: the patent aims at improving the existing extrusion die, particularly the extrusion concave die, and describes the part of the innovation point in the form of a drawing, and details about the non-innovation point of the die and the rest part of the extruder are not provided.

The technical features of the present invention which are not described in the above embodiments may be implemented by or using the prior art, and are not described herein again, of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and variations, modifications, additions or substitutions which may be made by those skilled in the art within the spirit and scope of the present invention should also fall within the protection scope of the present invention.