CN-121992283-A - Preparation method of regenerated aluminum profile extrusion die with uniformly distributed stress

CN121992283ACN 121992283 ACN121992283 ACN 121992283ACN-121992283-A

Abstract

The invention discloses a preparation method of a regenerated aluminum profile extrusion die with uniformly distributed stress, which relates to the field of regenerated aluminum profile extrusion dies and comprises the steps of S1, preparing a base material, namely mixing 92% -94% of W6Mo5Cr4V2 high-speed steel, 5% -7% of Cu-Ni alloy, 0.5% -1% of rare earth element Ce and 0.5% -1% of carbide WC according to the mass ratio, S2, carrying out gradient heat treatment, namely sequentially carrying out preheating, quenching and tempering on a base material blank, S3, carrying out cavity bionic design and processing, namely adopting a bionic honeycomb structure to design a die cavity according to the section size of the regenerated aluminum profile, accurately controlling the temperature, the heating rate and the heat preservation time of each stage by adopting a gradient heat treatment process of 'two-stage preheating-rapid quenching-three tempering', and simultaneously adopting high-purity nitrogen to accurately cool, achieving the effects of eliminating residual stress in the base material and optimizing the uniformity of a structure, and avoiding internal stress accumulation generated by imperfect heat treatment process.

Inventors

ZHANG SHENGEN
ZHANG BAILIN
PENG BINGFENG
ZHOU ZHIPENG
LIU YUE
LIU HU
HONG XIXI

Assignees

南昌大学
江西保太有色金属集团有限公司
江西金连升铝业有限公司

Dates

Publication Date: 20260508
Application Date: 20260225

Claims (10)

1. The preparation method of the regenerated aluminum profile extrusion die with uniformly distributed stress is characterized by comprising the following steps of: S1, preparing a base material, namely mixing 92-94% of W6Mo5Cr4V2 high-speed steel, 5-7% of Cu-Ni alloy, 0.5-1% of rare earth element Ce and 0.5-1% of carbide WC according to the mass ratio, wherein the mass ratio of Cu to Ni in the Cu-Ni alloy is 7:3, feeding the mixed raw materials into a vacuum induction smelting furnace, smelting for 2-2.5h at the temperature of 1550-1600 ℃, controlling the vacuum degree in the smelting process to be less than or equal to 30Pa, then adopting a directional solidification technology, solidifying the smelted raw materials into a die base material blank at the cooling rate of 5-8 ℃ per minute, and controlling the hardness of the base material blank to be 28-32HRC; s2, carrying out gradient heat treatment, namely sequentially carrying out preheating, quenching and tempering treatment on the base material blank; wherein, preheating, namely firstly preserving the heat of a base material blank for 1-1.5 hours at 650-680 ℃, then raising the temperature to 850-880 ℃ at the temperature raising rate of 10-15 ℃ per minute, and preserving the heat for 2-3 hours at the temperature; Quenching, namely heating to 1180-1220 ℃ at a set rate, preserving the temperature of the base material blank for 1.5-2h at the temperature, and then cooling to below 200 ℃ at a cooling rate of 50-60 ℃ per second by adopting a nitrogen cooling mode; tempering, namely placing the quenched base material blank at 560-580 ℃ for 2-2.5h, cooling to room temperature along with a furnace, repeating the tempering operation for 3 times, and controlling the hardness of the final base material at 62-65HRC; s3, designing and processing a die cavity in a bionic honeycomb structure according to the section size of the regenerated aluminum profile, wherein the wall thickness difference of the designed die cavity is less than or equal to 0.8mm, and arc transition of R3-R5mm is arranged at the corner of the die cavity; Adopting a five-axis linkage machining center to machine a cavity, controlling the rotating speed of a main shaft to be 8000-10000r/min in the machining process, controlling the feeding speed to be 150-200mm/min, and adopting laser detection after machining is finished; S4, surface strengthening treatment, namely sequentially carrying out sand blasting treatment, plasma spraying, hole sealing treatment and aging treatment on the die cavity; Wherein, the sand blasting treatment is that sand blasting treatment is carried out on the surface of the die cavity by adopting 120-150 mesh white corundum sand and the pressure of 0.4-0.6MPa, and the roughness Ra of the surface of the die cavity after the sand blasting treatment is controlled to be 1.2-1.5 mu m; Plasma spraying, namely performing plasma spraying on the surface of the die cavity after the sand blasting treatment, wherein a spraying material for the plasma spraying is Al 2 O 3 -Ti0 2 mixed powder, the mass ratio of Al 2 O 3 to TiO 2 is 85:15, the spraying power is controlled to be 35-40kW, the spraying distance is controlled to be 100-120mm, and the thickness of a coating formed after the spraying is 50-80 mu m; Sealing the hole, namely sealing the hole of the coating by using an epoxy resin sealing agent, wherein the solid content of the epoxy resin sealing agent is more than or equal to 95 percent, and curing for 1 to 1.5 hours at the temperature of 80 to 100 ℃; And (3) aging treatment, namely after hole sealing treatment is finished, carrying out integral aging treatment on the die, preserving heat for 4-5 hours at the temperature of 180-200 ℃, then cooling to room temperature along with a furnace, and finally, keeping the surface hardness of the die at least equal to 850HV.
2. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress, which is disclosed in claim 1, is characterized in that the stirring speed of a vacuum induction melting furnace in the substrate preparation step is controlled to be 300-350r/min so as to ensure uniform alloy components, and the content deviation of W, mo, cr, V elements is less than or equal to +/-0.1% detected by a spectrum analyzer after melting is finished.
3. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress, as claimed in claim 1, is characterized in that the purity of nitrogen used in quenching and cooling in the gradient heat treatment step is more than or equal to 99.99%, and the temperature difference of each part of the die in the cooling process is controlled within +/-10 ℃, so that internal stress caused by overlarge temperature difference is avoided.
4. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress as claimed in claim 1, wherein the width of the cavity ribs of the bionic honeycomb structure in the cavity bionic design and processing step is 2-3mm, the spacing of the ribs is 5-8mm, and the connection angle between the ribs and the cavity wall is 120 degrees, so that the stability and the stress dispersion capability of the cavity structure are improved.
5. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress, as claimed in claim 1, is characterized in that before plasma spraying in the surface strengthening treatment step, alcohol ultrasonic cleaning is carried out on the surface of a die cavity, the cleaning power is controlled to be 300-400W, the cleaning time is controlled to be 15-20min, so that oil stains and impurities on the surface are removed, and the bonding force of a coating is ensured to be more than or equal to 50MPa.
6. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress as claimed in claim 1, wherein a water-cooled copper die is adopted in the directional solidification in the substrate preparation step, the grain size of a die substrate blank is controlled to be 5-10 mu m, and stress concentration caused by coarse grains is avoided.
7. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress as claimed in claim 1, wherein the five-axis linkage machining center in the cavity bionic design and machining step adopts a diamond cutter with the hardness of more than or equal to 90HRC, and the machining process adopts cutting fluid with the cooling speed of more than or equal to 80 ℃ per minute for cooling, so that oxidization or microcracks on the surface of the die are prevented from being generated due to overheating.
8. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress as claimed in claim 1, wherein the spraying angle of the white corundum sand is controlled to be 45-60 degrees during the sand blasting treatment in the sand blasting treatment step, and the spraying path adopts reciprocating uniform movement, so that the uniform sand blasting of all areas on the surface of the die cavity is ensured, and the difference of surface roughness caused by excessive or insufficient local sand blasting is avoided.
9. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress, as set forth in claim 1, is characterized in that in the preheating stage of the gradient heat treatment step, after the temperature is raised to 850-880 ℃, temperature inspection is required in the heat preservation process of the substrate blank, the temperatures of different areas of the substrate blank are recorded every 30min, the temperature deviation of each area is ensured to be less than or equal to +/-5 ℃, and the substrate structure is ensured to be uniformly transformed.
10. The method for preparing the regenerated aluminum profile extrusion die with uniformly distributed stress according to claim 1, wherein after hole sealing treatment in the surface strengthening treatment step is completed, appearance detection and porosity detection are required to be carried out on the surface of a die cavity, and visual combined magnifying glass inspection is adopted for appearance detection, so that the coating is free from sealing leakage and bubbling phenomena.

Description

Preparation method of regenerated aluminum profile extrusion die with uniformly distributed stress Technical Field The invention relates to the field of regenerated aluminum profile extrusion dies, in particular to a preparation method of a regenerated aluminum profile extrusion die with uniformly distributed stress. Background Along with the continuous improvement of the global resource recycling demand, the renewable aluminum industry continuously expands the application scale in the fields of automobile light weight, building structure upgrading, rail traffic equipment manufacturing and the like by virtue of the core advantages of energy conservation, consumption reduction and emission reduction. The extrusion molding is used as a core process for producing the regenerated aluminum profile, the technical level of the extrusion molding directly determines the quality and the production efficiency of the profile product, and the extrusion mold is used as a key tool of the process, so that the performance is more important, namely the mold is required to bear the high temperature and high pressure effects in the extrusion process of the regenerated aluminum for a long time, and is required to resist the severe friction and periodic alternating stress between an aluminum melt and the surface of a cavity, and the working condition is extremely severe. However, the existing preparation technology of the regenerated aluminum profile extrusion die has a multi-dimensional short plate, so that the problem of uneven die stress distribution is outstanding, and the problem becomes a core bottleneck for restricting production stability and economy. Firstly, in the aspect of designing a die base material, the traditional technology mostly adopts single-component high-speed steel (such as W6Mo5Cr4V 2) or hot working die steel (such as H13), and the materials have certain high-temperature strength, but have two key defects that firstly, the heat conduction performance is poor, the temperature difference between the surface of a die cavity and a core part can reach 80-100 ℃ in the extrusion process, obvious thermal stress gradient is easy to form, secondly, the toughness and fatigue resistance are unbalanced, and weak parts such as the corners, ribs and the like of the die are easy to initiate microcracks under the action of long-term alternating stress, the crack expansion speed is high, and macroscopic cracking is finally initiated. Therefore, it is necessary to provide a method for preparing a secondary aluminum profile extrusion die with uniformly distributed stress to solve the above problems. Disclosure of Invention The invention aims to provide a preparation method of a regenerated aluminum profile extrusion die with uniformly distributed stress, which aims to solve the problems that the traditional die has poor heat conduction performance, the temperature difference between the surface of a die cavity and a core part is large in the extrusion process, a significant thermal stress gradient is easy to form, the toughness and fatigue resistance are unbalanced, micro cracks are easy to occur at weak parts such as die corners and ribs under the action of long-term alternating stress, the crack expansion speed is high, and macroscopic cracking is finally initiated. In order to achieve the aim, the invention provides the following technical scheme that the preparation method of the regenerated aluminum profile extrusion die with uniformly distributed stress comprises the following steps: S1, preparing a base material, namely mixing 92-94% of W6Mo5Cr4V2 high-speed steel, 5-7% of Cu-Ni alloy, 0.5-1% of rare earth element Ce and 0.5-1% of carbide WC according to the mass ratio, wherein the mass ratio of Cu to Ni in the Cu-Ni alloy is 7:3, feeding the mixed raw materials into a vacuum induction smelting furnace, smelting for 2-2.5h at the temperature of 1550-1600 ℃, controlling the vacuum degree in the smelting process to be less than or equal to 30Pa, then adopting a directional solidification technology, solidifying the smelted raw materials into a die base material blank at the cooling rate of 5-8 ℃ per minute, and controlling the hardness of the base material blank to be 28-32HRC; s2, carrying out gradient heat treatment, namely sequentially carrying out preheating, quenching and tempering treatment on the base material blank; Wherein, preheating is that firstly preserving heat for 1-1.5h at 650-680 ℃, then heating to 850-880 ℃ at a heating rate of 10-15 ℃ per min, and preserving heat for 2-3h at the temperature; Quenching, namely heating to 1180-1220 ℃ at a set rate, preserving heat for 1.5-2h at the temperature, and then cooling to below 200 ℃ at a cooling rate of 50-60 ℃ per second by adopting a nitrogen cooling mode; tempering, namely placing the quenched base material blank at 560-580 ℃ for 2-2.5h, cooling to room temperature along with a furnace, repeating the tempering operation for 3 times, and controlling the ha