CN103394542B - Rare earth magnesium alloy extrusion method - Google Patents

Abstract

Rare earth magnesium alloy extrusion die and extrusion method. Equal channel angular extrusion (ECAP) is achieved by making the billet undergo pure shear deformation, and the original purpose is to introduce strong plastic deformation without changing the cross-sectional area of the sample. Most of the currently used equal channel angular extrusion dies use two halves of the die, and the outer surface of the product made by this die is not smooth and easy to deform. The composition of the present invention includes: a mold base (1), a mold jacket (2) is installed on the mold base, a mold inner core (4) is installed inside the inner core installation hole (3) of the mold jacket, and the The mounting hole of the inner core communicates with the discharge port (5) of the mold jacket, the inner core of the mold has the inner hole (6) of the mold indenter, and the inner hole of the mold indenter is equipped with a mold indenter head (7). The invention is used for making rare earth magnesium alloy parts.

Description

Rare earth magnesium alloy extrusion method

Technical field:

The invention relates to a rare earth magnesium alloy extrusion die and an extrusion method.

Background technique:

Equal channel angular pressing (ECAP) technology, as one of the effective methods to obtain large-size submicron or nanoscale bulk materials through strong plastic deformation, has been increasingly valued by the material science community. Equal channel angular pressing (ECAP) is realized by making the billet through pure shear deformation. It was developed by Segal and his collaborators in the early 1980s. The original purpose was to change the cross-sectional area of the sample. At the same time, strong plastic deformation is introduced. In the early 1990s, ECAP was further developed and applied as a strong plastic deformation method capable of obtaining ultrafine grains. Most of the currently used equal-channel angular extrusion dies use two-half dies. The outer surface of the product made by this kind of die is not smooth, easy to deform, and cannot realize multi-pass repeated extrusion. During the extrusion process, the alloy is easy to enter the gap of the extrusion die, the diameter of the extruded rod is easy to change, and it is easy to cause dead mold. Moreover, the mold in the form of two halves often needs to be fixed with bolts. Since the extrusion process is high-temperature extrusion, the fixing bolts must be high-strength, high-temperature-resistant bolts, which increases the manufacturing cost of the mold. Once the mold expands, it is very inconvenient to disassemble the mold.

Invention content:

The object of the present invention is to provide a rare earth magnesium alloy extrusion die and extrusion method.

Above-mentioned purpose realizes by following technical scheme:

A rare earth magnesium alloy extrusion die, which comprises: a mold base, a mold jacket is installed on the mold base, a mold inner core is installed inside the inner core installation hole of the mold jacket, and the inner core is installed The hole communicates with the discharge port of the mold jacket, the mold inner core has a mold pressure head inner hole, and a mold pressure head is installed inside the mold pressure head inner hole.

In the rare earth magnesium alloy extrusion die, the inner core installation hole is an L-shaped through hole, and the inner core installation hole includes a horizontal channel and a vertical channel, the horizontal channel, the vertical channel The intersection angle of the included angle Φ=90°, the circumscribed arc angle ψ is 37°, the circumscribed arc radius R is 0.5 mm, and the diameter of the channel is 14 mm.

In the rare earth magnesium alloy extrusion die, there are bolt fixing holes on the die base.

A rare earth magnesium alloy extrusion method. When extruding one time, the extruded bar is coated with high-temperature grease and heated to the extrusion temperature together with the mold. When the temperature of the bar is measured by a thermometer at 250°C, extrusion begins. Pressing, the extrusion speed is 2mm/s, the length of the bar is slightly smaller than the length of the channel, start the extruder, apply high-temperature grease to the extrusion punch, align it with the mold channel, and keep extruding at a uniform speed. After the bar has completely passed the right-angle bend, the bar will automatically fall out of the mold, and the extrusion punch will be taken out by using a special tool, and the second pass of extrusion will be performed.

In the rare earth magnesium alloy extrusion method, the bars extruded one by one, keeping the direction in which the bar comes out of the die, without rotating at any angle, are put into the die, and the extrusion temperature is 270-280°C. Extrusion speed 2mm/s; Since the diameter remains unchanged before and after extrusion, the bar can be smoothly put into the mold; start the extrusion machine, apply high-temperature grease to the extrusion punch, align it with the mold channel, and maintain a uniform speed Carry out extrusion; when the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

In the rare earth magnesium alloy extrusion method, the extruded bar is kept in the direction in which the bar comes out of the mold, rotated 90 degrees, and put into the mold at an extrusion temperature of 270-280°C. Press speed 2mm/s; Since the diameter remains unchanged before and after extrusion, the bar can be smoothly put into the mold; start the extrusion machine, apply high-temperature grease to the extrusion punch, align it with the mold channel, and keep a uniform speed Extrusion; after the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

In the rare earth magnesium alloy extrusion method, the extruded bar is kept in the direction in which the bar comes out of the die, rotated 180 degrees, and put into the die at an extrusion temperature of 270-280°C. Press speed 2mm/s; Since the diameter remains unchanged before and after extrusion, the bar can be smoothly put into the mold; start the extrusion machine, apply high-temperature grease to the extrusion punch, align it with the mold channel, and keep a uniform speed Extrusion; after the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

Beneficial effect:

The mold designed by the method of fixing the two half-cores with an integral jacket has two passages with equal cross-sections, which intersect and are completely connected at a certain angle. The inner intersection angle of the two passages is Φ, and the outer arc angle is ψ. In the process of equal-channel angular extrusion, the sample that closely matches the channel size in the die and is well lubricated with the die wall is extruded downward under the action of the pressure P of the punch. When passing through the intersection of the two channels, The sample produces approximately ideal shear deformation. Since the cross-sectional shape and area of the material are not changed, repeated extrusion can make the strain of each deformation accumulate and superimpose to reach a considerable total strain.

The invention does not change the cross-sectional area of the material, but only needs to overcome the friction between the sample and the mold, so only a small working pressure is required. Taking magnesium alloy as an example, only 1 to 3 tons of pressure is required to extrude a rod with a diameter of 8 to 14 mm; since the cross-sectional area of the rod remains unchanged, it is possible to repeatedly extrude the same sample to introduce more pressure. High plastic strain realizes repeated orientation and uniform shear deformation of the material. The use of the mold is relatively convenient, as long as the mechanical performance testing machine for testing can be used to complete the corresponding extrusion production; the mold jacket and inner core are cuboid, which is convenient for the production and manufacture of the mold, and the mold is preheated by using heating tools; the inner core and outer jacket The use of transition fit ensures the tightness of the mold fit, increases the wrapping force of the jacket to the inner core, and improves the life of the mold.

The present invention can realize repeated extrusion, and each extrusion introduces severe plastic deformation, so the equal channel angular extrusion has great potential to refine the crystal grains of polycrystalline materials to micron, submicron and even nanometer scales.

Description of drawings:

Accompanying drawing 1 is the structure diagram of the present invention.

Accompanying drawing 2 is the structure diagram of the mold jacket in accompanying drawing 1.

Accompanying drawing 3 is A-A sectional view of accompanying drawing 2.

Accompanying drawing 4 is the C-C sectional view of accompanying drawing 2.

Accompanying drawing 5 is the C-C sectional view of accompanying drawing 4.

Accompanying drawing 6 is a structural schematic diagram of the inner core of the mold in the accompanying drawing 1.

Accompanying drawing 7 is the top view of accompanying drawing 6.

Accompanying drawing 8 is a structural schematic diagram of the mold base in accompanying drawing 1.

Accompanying drawing 9 is the top view of accompanying drawing 8.

Accompanying drawing 10 is a structural schematic diagram of the mold indenter in accompanying drawing 1.

detailed description:

Example 1:

A rare earth magnesium alloy extrusion die, which consists of: a die base 1, a die cover 2 is installed on the die base, a die core 4 is installed inside the inner core mounting hole 3 of the die cover, and the The mounting hole of the inner core communicates with the discharge port 5 of the mold jacket, the inner core of the mold has a mold indenter inner hole 6, and a mold indenter 7 is installed inside the inner hole of the mold indenter.

Example 2:

According to the rare earth magnesium alloy extrusion die described in Example 1, the inner core installation hole is an L-shaped through hole, and the inner core installation hole includes a horizontal channel and a vertical channel, and the horizontal channel, the The intersecting angle of the included angle of the vertical channel is Φ=90°, the circumscribed arc angle ψ is 37°, the circumscribed arc radius R is 0.5 mm, and the diameter of the channel is 14 mm.

Example 3:

According to the rare earth magnesium alloy extrusion die described in Embodiment 1, there are bolt fixing holes 8 on the die base.

Example 4:

A rare earth magnesium alloy extrusion method. When extruding one time, the extruded bar is coated with high-temperature grease and heated to the extrusion temperature together with the mold. When the temperature of the bar is measured by a thermometer at 250°C, extrusion begins. Pressing, the extrusion speed is 2mm/s, the length of the bar is slightly smaller than the length of the channel, start the extruder, apply high-temperature grease to the extrusion punch, align it with the mold channel, and keep extruding at a uniform speed. After the bar has completely passed the right-angle bend, the bar will automatically fall out of the mold, and the extrusion punch will be taken out by using a special tool, and the second pass of extrusion will be performed.

Example 5:

According to the rare earth magnesium alloy extrusion method described in Example 4, the bars extruded one by one, keeping the direction in which the bars come out of the die, are not rotated at any angle, put into the die, and the extrusion temperature is 270 -280°C, extrusion speed 2mm/s; since the diameter remains unchanged before and after extrusion, the bar can be put into the mold smoothly; start the extrusion machine, apply high-temperature grease to the extrusion punch, and align it with the mold Extrude at a constant speed in the channel; when the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

Embodiment 6:

According to the rare earth magnesium alloy extrusion method described in Example 4, the bar stock extruded one by one, keeping the direction in which the bar stock comes out of the die, is rotated 90 degrees, put into the die, and the extrusion temperature is 270- 280°C, extrusion speed 2mm/s; since the diameter remains unchanged before and after extrusion, the bar can be put into the mold smoothly; start the extrusion machine, apply high-temperature grease to the extrusion punch, and align it with the mold channel , Extrude at a constant speed; when the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

Embodiment 7:

According to the rare earth magnesium alloy extrusion method described in Example 4, the bar stock extruded one by one, keeping the direction in which the bar stock comes out of the die, rotates 180 degrees, puts it into the die, and the extrusion temperature is 270- 280°C, extrusion speed 2mm/s; since the diameter remains unchanged before and after extrusion, the bar can be put into the mold smoothly; start the extrusion machine, apply high-temperature grease to the extrusion punch, and align it with the mold channel , Extrude at a constant speed; when the bar completely passes through the right-angle bend, the bar will automatically fall out of the mold; use a special tool to take out the extrusion punch.

Embodiment 8:

The above-mentioned rare earth magnesium alloy extrusion die

(1) Mold coat, the shape is shown in the figure

Material: H13, hot work die steel 4Cr5MoSiV1

Technical requirements: blank forging, annealing, quenching + tempering, martensite plus carbide structure

HRC46-50

The inner surface finish reaches R0.4

(2) The shape of the inner core of the mold is shown in the figure

Material: H13, hot work die steel 4Cr5MoSiV1

Technical requirements: blank forging, annealing, quenching + tempering, martensite plus carbide structure

HRC48-52

The internal and external surface finish reaches R0.4

(3) Mold base, the shape is shown in the figure

Material: 45

Technical requirements: Quenching + tempering to obtain martensite plus carbide structure

HRC48-52

(4) Mold tray, the shape is as shown in the figure

Material: 45

Technical requirements: Quenching + tempering to obtain martensite plus carbide structure

HRC48-52

(5) Mold pressure head, the shape is as shown in the figure

Material: 45

Technical requirements: rough extrusion forming, annealing, quenching + tempering, to obtain martensite plus carbide structure

HRC48-52

The outer surface finish reaches R0.4.

Claims (4)

1. a kind of magnesium-rare earth pressing method, is characterized in that：When carrying out a time extruding, the bar of extruding is applied and wipes high temperature Grease is heated to extrusion temperature with mould, when being 250 DEG C with the temperature of thermometer measure bar, starts to extrude, extruding Speed 2mm/s, the length of the described bar length to be slightly less than passage, start extruder, extruding drift is applied and wipes high temperature Grease, is directed at die channel, remains a constant speed and extruded, and treats that described bar passes through quarter bend, bar Automatic-falling completely Go out mould, using specific purpose tool, drift will be extruded and take out, and carry out two passage extruding；

The magnesium alloy rod extruding a diameter of 8 ~ 14 mm only needs 1 ~ 3 ton of pressure；Because the cross-sectional area of bar is constant, It is possible to realizing same sample being carried out repeat to extrude to introduce higher plastic strain, realize the orientation repeatedly, all of material Even detrusion；

In Equal-channel Angular Pressing, it is fitted close and the sample good with die wall lubrication with the channel size in mould It is pressed down against in the presence of the pressure P of drift, when through the connection line of two passages, sample produces the shearing of approximate ideal Deformation；

The rare earth magnesium alloy extrusion die that said method uses, its composition includes：Mold base, described mold base is installed There is die coat, mold core, described inner core installing hole and institute are installed inside the described inner core installing hole of die coat The discharging opening of the die coat stated communicates, and described mold core has die head endoporus, in the hole in described die head Portion is provided with die head；

Described inner core installing hole is L shape through hole, and described inner core installing hole includes horizontal channel, Vertical Channel, described water Flat passage, angle of intersection Φ=90 ° of the angle of described Vertical Channel, external arc angle ψ is 37 °, and external arc radius R are 0.5 Mm, a diameter of 14 mm of passage；

On described mold base, there is bolt fixing hole.

2. the magnesium-rare earth pressing method according to claim 1, is characterized in that：The bar that a time is squeezed out, protects Bar described in holding direction out from mould, does not rotate any angle, puts in mould, 270-280 DEG C of extrusion temperature, extruding Speed 2mm/s；Because before and after extruding, diameter keeps constant, mould can smoothly be put into by described bar；Start extruder, will squeeze Pressure drift applies and wipes Hmp grease, is directed at die channel, remains a constant speed and extruded；Treat that bar passes through quarter bend, rod completely Material Automatic-falling goes out mould；Using specific purpose tool, drift will be extruded and take out.

3. the magnesium-rare earth pressing method according to claim 1, is characterized in that：The bar that a time is squeezed out, protects Bar described in holding direction out from mould, rotation turn 90 degrees, and puts in mould, 270-280 DEG C of extrusion temperature, extrusion speed 2mm/s ；Because before and after extruding, diameter keeps constant, mould can smoothly be put into by described bar；Start extruder, by extruding punching Head applies and wipes Hmp grease, is directed at die channel, remains a constant speed and extruded；Treat that bar passes through quarter bend completely, bar is certainly The dynamic mould that comes off；Using specific purpose tool, drift will be extruded and take out.

4. the magnesium-rare earth pressing method according to claim 1, is characterized in that：The bar that a time is squeezed out, protects Bar described in holding direction out from mould, revolves turnback, puts in mould, 270-280 DEG C of extrusion temperature, extrusion speed 2mm/s ；Because before and after extruding, diameter keeps constant, mould can smoothly be put into by described bar；Start extruder, by extruding punching Head applies and wipes Hmp grease, is directed at die channel, remains a constant speed and extruded；Treat that bar passes through quarter bend completely, bar is certainly The dynamic mould that comes off；Using specific purpose tool, drift will be extruded and take out.