A heating method for high-precision aluminum alloy pipe blank near semi-solid extrusion molding
By combining in-furnace and out-of-furnace heating with heating and cooling cycles, the aluminum alloy billet is controlled to be in a near-semi-solid state 5-10°C above the solidus line. This solves the quality problem in the extrusion forming of high-precision aluminum alloy tube blanks, improves the pass rate, and reduces production costs.
Patent Information
- Application Number
- CN202311698970.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2043-12-12
AI Technical Summary
High-precision aluminum alloy tube blanks have defects such as poor surface quality, large wall thickness deviation, and microcracks during the extrusion molding process. Furthermore, the heating temperature is difficult to control precisely during semi-solid extrusion molding, resulting in low pass rate and high production cost.
A two-stage heating method is adopted, with in-furnace heating and out-of-furnace heating. The in-furnace preheating is below the solidus temperature, while the out-of-furnace heating is controlled by a temperature-regulating cycle to ensure that the aluminum alloy billet is 5-10°C above the solidus temperature, forming a near-semi-solid state, reducing deformation resistance and avoiding compositional segregation.
It significantly improves the extrusion molding quality of high-precision aluminum alloy tube blanks, increases the pass rate, and controls production costs.
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Figure CN117619924B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of high-precision light alloy pipe blank preparation, in particular to a heating method for high-precision aluminum alloy pipe blank near semi-solid extrusion forming. BACKGROUND
[0002] High-precision aluminum alloy pipe blanks are usually formed by extrusion, and the extrusion forming temperature is 435-465℃. When extruded at this temperature, the material itself has large deformation resistance and poor flowability, so that after extrusion, defects such as poor surface quality, excessive wall thickness deviation, and micro-cracks in the pipe wall in the radial direction are prone to occur, resulting in a low pass rate of high-precision aluminum alloy pipe blanks, thereby making the production cost of high-precision aluminum alloy pipes high. High-precision aluminum alloy pipe blanks are formed by semi-solid extrusion, which can effectively solve the problems of poor surface quality, excessive wall thickness deviation, and micro-cracks in the pipe wall in the radial direction existing in the current extrusion production. However, the semi-solid extrusion requires high heating temperature of the blank and high internal and external temperature difference. In actual production, even if the aluminum alloy blank is heated according to the set heating process in the medium-frequency heating furnace, there are still problems of non-compliance or excessive temperature difference, and there are still a certain proportion of problems of poor surface quality, excessive wall thickness deviation, and micro-cracks in the pipe wall in the radial direction, or composition segregation of the pipe blank material after extrusion forming. Therefore, when high-precision aluminum alloy pipe blanks are formed by semi-solid extrusion, the control of heating temperature becomes a technical problem to be solved. SUMMARY
[0003] In order to overcome the deficiencies in the background art, the present application discloses a heating method for high-precision aluminum alloy pipe blank near semi-solid extrusion forming. The aluminum alloy blank is a semi-solid blank. The heating before extrusion of the aluminum alloy blank includes two heating processes of furnace heating and furnace-out heating. The furnace heating preheats the aluminum alloy blank to control its temperature below the solidus temperature. The furnace-out heating uses a temperature rising and falling cycle to complete the final heating of the aluminum alloy blank, accurately controls the temperature and internal and external temperature difference of the aluminum alloy blank, controls the overall temperature of the aluminum alloy blank at 5-10℃ above the solidus temperature, and forms a small amount of liquid phase organization between the grain boundaries of the aluminum alloy blank, so that the aluminum alloy blank is in a near semi-solid state. When the aluminum alloy blank is extruded in a near semi-solid state, the deformation resistance can be greatly reduced, and the composition segregation problem caused by the aggregation of liquid phase composition during extrusion in a semi-solid state can also be avoided, thereby greatly improving the extrusion forming quality of high-precision aluminum alloy pipe blanks, improving the pass rate of high-precision aluminum alloy pipe blanks, and effectively controlling the production cost of high-precision aluminum alloy pipes.
[0004] In order to achieve the object of the present application, the present application adopts the following technical solution: a heating method for high-precision aluminum alloy pipe blank near semi-solid extrusion forming, the aluminum alloy blank is a semi-solid blank, the semi-solid blank is cast into an ingot through semi-solid slurry casting; the aluminum alloy blank heating includes two heating of furnace heating and out-of-furnace heating; wherein the furnace heating is used for preheating of the aluminum alloy blank, the heating temperature is controlled below the solidus temperature, preventing the aluminum alloy blank from appearing excessive liquid phase composition between grain boundaries due to poor furnace heating temperature control, and simultaneously shortening the out-of-furnace heating time; wherein the out-of-furnace heating is used for final heating of the aluminum alloy blank, accurately controlling the temperature and internal and external temperature difference of the aluminum alloy blank, ensuring the overall temperature to be controlled above the solidus temperature by 5-10℃, so that a small amount of liquid phase organization is formed between the grain boundaries of the aluminum alloy blank, and the aluminum alloy blank is in a near semi-solid state; when the aluminum alloy blank is extruded in the near semi-solid state, the deformation resistance can be greatly reduced, and the composition segregation problem caused by liquid phase composition aggregation during extrusion in the semi-solid state can also be avoided, thereby greatly improving the extrusion forming quality of the high-precision aluminum alloy pipe blank and improving the qualified rate of the high-precision aluminum alloy pipe blank.
[0005] Further, the heating furnace for the furnace heating adopts a medium-frequency induction furnace; the final temperature of the furnace heating is 5-10℃ below the solidus temperature, and the temperature is maintained for 0.5-1.0 hours; the aluminum alloy blank is heated to the set temperature in the furnace, and the time required for accurately controlling the final temperature of the aluminum alloy blank during the out-of-furnace heating can be shortened; it is to be further explained that the setting of the final heating temperature in the furnace is determined according to the actual solidus temperature and deviation of the aluminum alloy blank, and the temperature is determined by actual measurement in the laboratory; if the actual solidus temperature of the aluminum alloy blank is relatively stable, 5℃ below the average value of the solidus temperature can be selected; if the actual solidus temperature of the aluminum alloy blank has a large deviation, 10℃ below the average value of the solidus temperature can be selected.
[0006] Further, the furnace heating uses a power frequency induction coil to heat and rise in temperature, and the power frequency induction heating aims to improve the heating depth as much as possible, which is conducive to the consistency of the internal and external temperatures of the aluminum alloy blank after final heating; the heating and rising in temperature process is carried out in a rising in temperature and falling in temperature cycle mode to prevent continuous heating from causing the local temperature of the aluminum alloy blank to be too high; in each rising in temperature and falling in temperature cycle, the rising and falling in temperature step temperature is 2.0-5.0℃, and the temperature of the adjacent rising in temperature and falling in temperature cycle is increased by 1.0-2.0℃, that is, the overall temperature of the aluminum alloy blank is increased by 1.0-2.0℃ after each rising in temperature and falling in temperature cycle; the furnace heating temperature is finally increased to 5-10℃ above the solidus temperature; the furnace heating of the aluminum alloy blank uses the rising in temperature and falling in temperature cycle mode and controls the rising in temperature and falling in temperature rate, which gives the aluminum alloy blank time to exchange heat and achieve overall temperature balance during the heating and rising in temperature process and the heating and falling in temperature process, so as to achieve the purpose of precisely controlling the overall temperature and the internal and external temperature difference of the aluminum alloy blank and prevent local overheating or temperature deviation; it is additionally stated that the setting of the final heating temperature outside the furnace is determined according to the actual solidus temperature and deviation of the aluminum alloy blank; if the actual solidus temperature of the aluminum alloy blank is relatively stable, 5℃ above the average value of the solidus temperature can be selected; if the actual solidus temperature of the aluminum alloy blank has a large deviation, 10℃ above the average value of the solidus temperature can be selected; in addition, during the furnace heating process, the extrusion operator can observe the surface color of the aluminum alloy blank at any time, and the surface color of the aluminum alloy blank is used to assist in judging whether the overall temperature of the aluminum alloy blank reaches the final set temperature, so as to further improve the extrusion qualification rate of the high-precision aluminum alloy pipe blank.
[0007] Further, during the rising in temperature, the rising in temperature rate is controlled to be 1.0-2.0℃ / min by controlling the power frequency induction output power.
[0008] Further, during the falling in temperature, the falling in temperature rate is controlled to be 1.0-2.0℃ / min by controlling the power frequency induction output power.
[0009] Further, when the furnace heating temperature of the aluminum alloy blank reaches the set temperature, the temperature is kept constant for 1-5 minutes by controlling the power frequency induction output power, and the aluminum alloy blank is given time to exchange heat and achieve overall temperature balance, and at the same time, during the holding time, the temperature of the aluminum alloy blank is above the solidus temperature, so that a small amount of liquid phase organization is generated by the melting of the solid phase components between the grain boundaries, so that the aluminum alloy blank is in a near semi-solid state.
[0010] With the technical scheme as described above, the application has the following beneficial effects: the heating method for near semi-solid extrusion forming of high-precision aluminum alloy pipe blank disclosed by the application uses semi-solid blank for the aluminum alloy blank; the heating before extrusion of the aluminum alloy blank includes two heating processes of furnace heating and out-of-furnace heating, wherein the furnace heating is used for preheating the aluminum alloy blank and controlling the temperature of the aluminum alloy blank below the solidus temperature; the out-of-furnace heating is used for completing the final heating of the aluminum alloy blank in the temperature rising and falling cycle mode, accurately controlling the temperature and the internal and external temperature difference of the aluminum alloy blank, and controlling the overall temperature of the aluminum alloy blank above the solidus temperature by 5-10℃, so that a small amount of liquid phase organization is formed between the grain boundaries of the aluminum alloy blank and the aluminum alloy blank is in the near semi-solid state; the aluminum alloy blank can greatly reduce the deformation resistance when extruded in the near semi-solid state, and can also avoid the composition segregation problem caused by the aggregation of liquid phase composition when extruded in the semi-solid state, thereby greatly improving the extrusion forming quality of the high-precision aluminum alloy pipe blank, improving the qualified rate of the high-precision aluminum alloy pipe blank, and effectively controlling the production cost of the high-precision aluminum alloy pipe. BRIEF DESCRIPTION OF DRAWINGS
[0011] Figure 1 Table for controlling the out-of-furnace heating process of the aluminum alloy blank. DETAILED DESCRIPTION
[0012] The application can be explained in detail through the following examples, and the purpose of disclosing the application is to protect all technical improvements within the scope of the application.
[0013] A heating method for near semi-solid extrusion forming of high-precision aluminum alloy pipe blank, the aluminum alloy blank is ZL104 semi-solid round bar blank, and the theoretical solidus temperature thereof is 577℃; before extrusion of the aluminum alloy blank, the aluminum alloy blank is first heated to 570℃ in a medium-frequency heating furnace, and then taken out after holding for 0.5 hours; after being taken out, the aluminum alloy blank is placed on a support table and heated by a power frequency induction heating coil, the heating process adopts the temperature rising and falling cycle, and finally heated to 585℃, and then held for 3 minutes, and then the near semi-solid extrusion forming is performed to process the high-precision aluminum alloy pipe blank.
[0014] Specific reference is made to the drawings attached to the specification Figure 1 : the out-of-furnace temperature of the aluminum alloy blank is 570℃, and the aluminum alloy blank is heated by 12 times of temperature rising and falling heating cycles after being taken out;
[0015] In the first 5 times of temperature rising and falling heating cycles, the temperature rising step is 3.0℃ (i.e. 3.0℃ per time), and the temperature falling step is 2.0℃ (i.e. 1.0℃ per time), that is, the temperature of the aluminum alloy blank is increased by 1.0℃ through one temperature rising and falling heating cycle; in the temperature rising and falling heating cycle, the temperature rising rate is controlled at 2.0℃ / min and the temperature falling rate is controlled at 1.0℃ / min by controlling the power frequency induction output power;
[0016] In the 6th-11th heating and cooling heating cycle, the temperature rise step is 3.0 DEG C (i.e. each temperature rise 3.0 DEG C), the temperature drop step is 2.0 DEG C (each temperature drop 1.0 DEG C), through a heating and cooling heating cycle, the temperature of the aluminum alloy blank is increased by 1.0 DEG C; in the heating and cooling heating cycle, the heating and cooling rates are controlled at 1.0 DEG C / min by controlling the power frequency induction output power;
[0017] In the 12th heating cycle, after the aluminum alloy blank is heated to the set 585 DEG C, the output power of the power frequency induction is controlled, and the temperature is kept constant for 3-5 minutes according to the heating process requirements; during the holding process, the extrusion operator observes the surface color of the aluminum alloy blank at any time, and when the surface color of the aluminum alloy blank reaches the requirement according to experience, the extrusion processing is carried out after the holding is delayed for 5-10 seconds.
[0018] The part of the application not described in detail is the prior art.
Claims
1. A heating method for near semi-solid extrusion of high-precision aluminum alloy pipe blank, the aluminum alloy blank is a semi-solid blank; characterized in that: The aluminum alloy blank heating includes two heating of furnace heating and out-of-furnace heating; the furnace heating temperature is controlled below the solidus temperature, and the out-of-furnace heating final temperature is controlled above the solidus temperature; the heating furnace of the furnace heating adopts a medium-frequency induction furnace; the final heating temperature of the furnace heating is 5-10℃ below the solidus temperature of the aluminum alloy blank, and the heat preservation time is 0.5-1.0 hours; the out-of-furnace heating adopts power frequency induction heating to increase the temperature; the heating process is carried out in a temperature increasing and decreasing cycle; in each temperature increasing and decreasing cycle, the temperature increasing and decreasing step is 2.0-5.0℃; the temperature of adjacent temperature increasing and decreasing cycles is increased by 1.0-2.0℃; and the out-of-furnace heating temperature is finally increased to 5-10℃ above the solidus temperature.
2. The heating method for near semi-solid extrusion of high-precision aluminum alloy pipe blank according to claim 1, characterized in that: When increasing the temperature, the output power of the power frequency induction is controlled to control the temperature increasing rate to be 1.0-2.0℃ / min.
3. The heating method of the high-precision aluminum alloy pipe blank near the semi-solid extrusion forming according to claim 1, characterized in that: When decreasing the temperature, the output power of the power frequency induction is controlled to control the temperature decreasing rate to be 1.0-2.0℃ / min.
4. The method of claim 1, wherein the high-precision aluminum alloy pipe blank is heated by a near semi-solid extrusion forming method. When the out-of-furnace heating temperature of the aluminum alloy blank reaches the set temperature, the output power of the power frequency induction is controlled to keep the temperature constant for 1-5 minutes.
Citation Information
Patent Citations
Preparation method suitable for secondary heating of semisolid thixotropy deformation aluminum alloy
CN104213058A