WO2022062727A1

WO2022062727A1 - Preparation method for motor shell aluminum profile, and motor shell and motor

Info

Publication number: WO2022062727A1
Application number: PCT/CN2021/111373
Authority: WO
Inventors: 满士国; 邢阳
Original assignee: 广东坚美铝型材厂（集团）有限公司; 佛山坚美铝业有限公司
Priority date: 2020-09-28
Filing date: 2021-08-08
Publication date: 2022-03-31
Also published as: CN112226657B; CN112226657A

Abstract

The present invention discloses a preparation method for motor shell aluminum profile, comprising: preparing raw materials in proportion, obtaining an aluminum ingot after smelting and casting, homogenizing and pressing the aluminum ingot to obtain a semi-finished motor shell, and performing cooling, straightening, and aging treatment on the semi-finished motor shell to obtain finished motor shell aluminum profile. Correspondingly, the present invention further discloses a motor shell which is prepared by using the described preparation method; and the present invention further discloses a motor which comprises the motor shell. The implementation of the present invention can obtain the aluminum profile which is low in costs and good in mechanical and pressing properties; the present invention is suitable for production of motor shells in complex shapes, and can also improve the pressing speed and the production efficiency.

Description

Preparation method of aluminum profile for motor housing, motor housing and motor

technical field

The invention relates to the technical field of motor housing manufacturing, in particular to a preparation method of an aluminum profile for a motor housing, an electrode housing and a motor.

Background technique

Motors are one of the most commonly used drive devices in the industry. Traditional motor housings are made of cast iron or aluminum alloy. These two types of production processes are complicated and the manufacturing cost is high. The cast iron motor shell is heavy and inconvenient to use; the material density of the aluminum alloy die-casting motor shell is poor, which is easy to cause casting defects such as pores and sand holes, and the surface roughness is poor, which seriously affects the corrosion resistance of the motor, resulting in Motor service life is low. With the advancement of technology, some manufacturers gradually put forward the technical idea of using the extrusion method to produce the motor housing. In order to realize this technical idea, the aluminum alloy must have good extrudability, weldability, appropriate strength and lower cost. The existing low-cost aluminum alloys have the problems of substandard mechanical properties, insufficient hardness, and poor forming (extrusion) performance, resulting in large deviations in shape, position and size, and prone to cracking and deformation of heat dissipation ribs during extrusion, which is difficult to achieve. Meet the production of motor housing.

In view of the above problems, Chinese patent CN 108754362A provides a production method of aluminum alloy motor housing for new energy vehicles. , Mg 0.35～0.60%, Ti≤0.1%, Cr≤0.05%, Zn≤0.15%, the remaining single impurities≤0.05%, the total impurities≤0.15%, the balance Al; the yield strength after aging is 240～249MPa, the resistance The tensile strength is 265-273MPa, and the elongation is 9.5-12.0%. Its strength is relatively low, and it is difficult to meet the needs of some special occasions; and its extrusion speed is slow and production efficiency is low. Moreover, the elongation of this aluminum alloy is only 9.5-12%, and its extrusion performance is poor, which will greatly limit its application in some complex-shaped electrode casings.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for preparing an aluminum profile of an electrode shell, and the prepared aluminum profile has low cost, excellent mechanical properties, and excellent extrusion performance, and can be suitable for the production of complex-shaped motor shells; And it can increase the extrusion speed and improve production efficiency.

The technical problem to be solved by the present invention is to provide a motor casing with high strength, high elongation and small error in shape and position.

The technical problem to be solved by the present invention is to provide a motor.

In order to solve the above-mentioned technical problems, the present invention provides a preparation method of an aluminum profile of a motor casing, which comprises:

(1) prepare raw material for subsequent use according to the proportion; wherein, the raw material formula by weight percentage is as follows:

Si 0.6～0.7%, Fe≤0.25%, Cu 0.1～0.2%, Mn≤0.05%, Mg 0.8～0.95%, Cr 0.05～0.1%, Zn≤0.1%, Ti≤0.05%, total other impurities≤0.15% , the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

(3) Homogenizing the aluminum ingot; wherein, the homogenizing temperature is 550-580° C., and the holding time is 6-8 h;

(4) extruding the homogenized aluminum ingot to obtain a semi-finished motor shell; wherein, the extrusion temperature is 480-540 °C, and the extrusion speed is 2-10 m/min;

(5) cooling the semi-finished product of the motor shell;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.2-1%;

(7) The straightened semi-finished product of the motor shell is subjected to aging treatment to obtain the finished product of the aluminum profile of the motor shell; wherein, the aging temperature is 160-180°C, and the aging time is 6-10h.

As the improvement of above-mentioned technical scheme, in step (1), the raw material formula by weight percentage is as follows:

Si 0.6～0.64%, Fe 0.05～0.25%, Cu 0.15～0.19%, Mn≤0.04%, Mg 0.84～0.9%, Cr 0.05～0.08%, Zn≤0.05%, Ti≤0.02%, total other impurities≤0.1 %, the balance is aluminum;

And Mg/Si=1.38-1.44.

As the improvement of above-mentioned technical scheme, step (3) comprises:

(3.1) Homogenize the aluminum ingot at 550～580℃, and keep the temperature for 7～8h;

(3.2) The homogenized aluminum ingot is cooled to 180-200° C. with the furnace, and then cooled to room temperature after being released from the furnace.

As the improvement of above-mentioned technical scheme, step (4) comprises:

(4.1) Turning the aluminum ingot after homogenization;

(4.2) The aluminum ingot after turning treatment is extruded by using a split-flow combined die; wherein, the temperature of the split-flow combined die is 480～500℃, the extrusion speed is 3～7m/min, and the extrusion temperature is 480～500℃. 525°C, the extrusion outlet temperature is 510-530°C.

As an improvement of the above-mentioned technical solution, in step (5), one or two cooling modes of strong wind cooling, water mist cooling and water cooling are adopted to cool the semi-finished motor shell;

In step (6), the straightening amount is 0.5 to 1%;

In step (7), the aging temperature is 170-180° C., and the aging time is 7-8 h.

As an improvement of the above technical solution, in step (4.2), in the process of preparing the split-flow combined mold, high-purity nitrogen is used to quench the split-flow combined mold;

In step (5), water mist is used to cool the semi-finished motor housing.

As the improvement of above-mentioned technical scheme, step (2) comprises:

(2.1) Melting various raw materials at 700～760℃ to obtain alloy liquid;

(2.2) refining the alloy liquid at 700～730℃ for 15～30min;

(2.3) Let the refined alloy liquid stand for 20-30min;

(2.4) Cast the standing alloy liquid to obtain an aluminum ingot; wherein, the casting temperature is 700-720° C., and the casting speed is 50-80 mm/min.

As an improvement of the above technical solution, the tensile strength of the aluminum profile of the motor casing is 270-310 MPa, the yield strength is 240-270 MPa, the elongation is 15-20%, and the Brinell hardness is 95-115 N/mm ² .

Correspondingly, the present invention also discloses a motor casing, which is prepared by the above-mentioned preparation method of the aluminum profile of the motor casing.

Correspondingly, the present invention also discloses a motor, which includes the above-mentioned motor housing.

Implement the present invention, have the following beneficial effects:

1. The aluminum profile of the motor shell in the present invention, its formula is: Si 0.6～0.7%, Fe≤0.25%, Cu 0.1～0.2%, Mn≤0.05%, Mg 0.8～0.95%, Cr 0.05～0.1%, Zn≤0.1%, Ti≤0.05%, the total of other impurities≤0.15%, and the balance is aluminum; through reasonable adjustment of the formula, the mechanical properties and extrusion properties of aluminum profiles can be effectively improved; specifically, the motor in the present invention The tensile strength of the shell aluminum profile is 270-310 MPa, the yield strength is 240-270 MPa, the elongation is 15-20%, and the Brinell hardness is 95-115 N/mm ² .

2. The aluminum profile in the present invention has an elongation rate of 15-20%, and the aluminum profile has excellent extrusion performance, which can be adapted to the manufacture of motor casings with complex shapes, and has a high extrusion rate and high production efficiency.

3. The motor shell profile in the present invention is produced by extrusion method, and its shape and position accuracy is higher than that of casting process; and after extrusion, the present invention adopts the cooling form of water mist cooling, and reasonably adjusts the cooling ribs and the shell The stress distribution between them ensures that the shape and position size does not change greatly during the cooling process, and ensures high shape and position accuracy.

Description of drawings

Fig. 1 is the flow chart of the preparation method of a kind of motor shell aluminum profile of the present invention;

FIG. 2 is a schematic structural diagram of a motor casing in an embodiment of the present invention.

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Only this statement, the present invention appears or will appear in the text up, down, left, right, front, rear, inner, outer and other orientation terms, only based on the accompanying drawings of the present invention, which are not specific to the present invention limited.

Referring to Fig. 1, the present invention discloses a preparation method of a motor shell profile, which comprises the following steps:

S1: Prepare raw materials according to the proportion for standby;

Wherein, the raw material formula by weight percentage is as follows:

Mg and Si are the main strengthening elements. Mg and Si can form the Mg ₂ Si phase and cooperate with the excess silicon phase to jointly strengthen the mechanical properties. With the increase of Mg ₂ Si phase and excess silicon content in the profile, the tensile strength, yield strength and quenching sensitivity of the profile increase, but the elongation decreases, and the extrusion performance of the profile deteriorates. For this purpose, Si is controlled to be 0.6-0.7%, Mg is 0.8-0.95%; preferably, Si is controlled to 0.6-0.64%, Mg is 0.84-0.9%, and Mg/Si is controlled to be 1.38-1.44, within this range The profile not only has good mechanical properties and extrusion properties, but also has a small tendency to weld cracks, which is convenient for the welding of motor casings in the later stage; further preferably, Mg/Si=1.41 is controlled.

Fe can form a hard and brittle alloy phase with Mn, Cr, Si, Al, etc., reducing the toughness of the profile, weakening its extrusion performance and corrosion resistance. With the increase of Fe content, the toughness of the profiles decreases significantly. Therefore, the Fe content is controlled to be no more than 0.25%, and preferably, the Fe content is controlled to be 0.05-0.25%.

Cu can improve the corrosion resistance of the profile and can also compensate for the strength loss of the parking effect, but Cu will also have a squeezing effect, reducing the anisotropy of the alloy. For this reason, Cu is controlled to be 0.1-0.2%; preferably, Cu is controlled to be 0.15-0.2%.

A small amount of Cr and Mn can refine the excess silicon phase and reduce the adverse effect of excess silicon on extrusion performance; at the same time, a small amount of Mn can also make the edge of the iron-containing brittle phase rounded and reduce the adverse effect of Fe on extrusion performance. However, higher content of Cr and Mn will increase the quenching sensitivity, which is not conducive to the control of shape, position and size. Therefore, Mn is controlled to be less than or equal to 0.05%, and Cr is controlled to be 0.05 to 0.1%. Preferably, Mn is controlled to be less than or equal to 0.04%, and Cr is 0.05-0.08%.

Ti can refine crystal grains and improve mechanical properties and formability. Ti content≤0.05%, preferably, control Ti≤0.02%.

Zn is an impurity element, and the content of Zn is less than or equal to 0.1%. Preferably, the content of Zn is controlled to be less than or equal to 0.05%. In addition, the profiles also contain some inevitable impurities, the total content of which should be less than or equal to 0.15%.

Among the existing alloys, the alloy with relatively low cost and relatively good extrusion performance and welding performance is 6061 alloy, and its composition is: Si 0.4-0.8%, Fe 0.7%, Cu 0.15-0.4%, Mn 0.15%, Mg 0.8-1.2%, Cr 0.04-0.35%, Zn 0.25%, Ti 0.15%, the total content of other impurities is less than or equal to 0.15%, and the balance is aluminum; the present invention reduces the content of Fe, Zn, and Ti, and passes Si, Cu, The joint adjustment of Mn, Mg and Cr ensures that the profiles have good mechanical properties, extrusion properties and welding properties. Moreover, in order to achieve the above technical effect, it is also necessary to cooperate with the subsequent preparation method of the present invention.

S2: smelting and casting raw materials to obtain aluminum ingots;

Specifically, S2 includes:

S21: melting various raw materials to obtain alloy liquid;

Specifically, the smelting temperature is 700-760°C. If the smelting temperature is too high, hydrogen absorption and oxidation will be increased, and if the temperature is too low, inclusions will easily occur.

S22: refining the alloy liquid;

Specifically, the refining temperature is 700-730° C., and the time is 15-30 minutes; nitrogen or argon is introduced into the refining process. The refining process helps to remove impurities in the alloy liquid, and the introduction of nitrogen or argon can effectively remove the hydrogen mixed in the alloy liquid.

S23: let the refined alloy liquid stand for 20-30 minutes;

S24: casting the standing alloy liquid to obtain an aluminum ingot;

Among them, the casting temperature is 700 to 720°C, and the casting speed is 50 to 80 mm/min.

S3: Homogenize the aluminum ingot;

Specifically, S3 includes:

S31: Homogenize the aluminum ingot at 550-580°C and keep the temperature for 6-8h;

Preferably, the homogenization temperature is 560-580°C, and the holding time is 7-8h. Homogenization can increase the extrusion speed and meet the forming requirements of the profile section requirements.

S32: Cool the homogenized aluminum ingot to 180-200° C. with the furnace, and then cool to room temperature after being released from the furnace.

Specifically, the aluminum ingot is first cooled to 180-200° C. with the furnace; then it is released from the furnace and cooled to room temperature in the air.

S4: extruding the homogenized aluminum ingot to obtain a semi-finished motor shell;

Specifically, S4 includes:

S41: turning the homogenized aluminum ingot;

Specifically, the oxide scale on the surface of the aluminum ingot is removed by turning, and the turning amount is 0.7-1.2% (taking a round cast bar as an example, the cutting thickness is 0.7-1.2% of its diameter).

S42: The aluminum ingot after turning is extruded by a split-flow combined die;

Specifically, since the aluminum profile of the motor casing in the present invention has many symmetrical parts and many hollow parts, a split-flow combined die is used for extrusion. In the design process of the split combined mold, the metal supply of the split hole in the symmetrical part and the selection of the working belt should be controlled as much as possible to avoid the tensile stress caused by the difference in flow rate, so as to ensure the dimensional accuracy of the product. In addition, in the mold forming process, it should be quenched with high-purity nitrogen, which can ensure the dimensional accuracy and surface smoothness of the die hole in the split-flow combined mold, thereby ensuring that the heat dissipation rib has a high hardness during the extrusion process.

Specifically, in the extrusion process, the temperature of the split combined die is 480-500°C, the extrusion speed is 2-10m/min, the extrusion temperature is 480-540°C, and the extrusion outlet temperature is 510-530°C. Preferably, the temperature of the split-flow combined die is 490-500°C, the extrusion speed is 3-7m/min, the extrusion temperature is 490-525°C, and the extrusion outlet temperature is 510-520°C.

The invention adopts a higher extrusion temperature, which can make the solid solution of various strengthening phases in the semi-finished product of the motor shell more sufficient, so that more strengthening phases are precipitated in the subsequent aging process, and various mechanical properties are improved. In addition, the formula of the profile in the present invention is reasonable, so that the extrusion speed is higher and the production efficiency is improved.

S5: Cool the semi-finished motor shell;

Specifically, on-line cooling and quenching treatment is performed on the semi-finished motor shell at the extrusion outlet, cooled to below 150°C, and then cooled to 20-50°C on a cooling bed. Among them, one or a combination of strong wind cooling, water mist cooling and water cooling can be selected for online cooling.

Preferably, water mist cooling is used in the online quenching process of the present invention; specifically, a plurality of atomizing nozzles arranged at the outlet of the extruder are used for cooling, and the air supply pressure of the atomizing nozzles is 5-10 bar, and the atomization of a single nozzle The amount of water is 0.1 to 0.3L/min. During the quenching and cooling process, stress will be generated inside the semi-finished product of the motor shell. If the stress is not properly controlled, deformation or even cracking will occur, which will affect the shape and dimensional accuracy and affect the mechanical properties. The structure of the motor casing in the present invention is relatively complex, which is a structure of a thick cylindrical casing and a plurality of thin heat dissipation ribs, and the heat dissipation conditions of the heat dissipation ribs and the thick cylindrical casing are different. If strong wind cooling or water cooling is used, the cooling speed of some parts will be too high, while the cooling speed of some parts will be too low, and the cooling speed cannot be matched, which is easy to cause deformation defects. In addition, when water is used for cooling, it is easy for water to form an instantaneous water vapor film on the surface of high-temperature profiles, and it is difficult for cooling water to break through this water vapor film in a timely and effective manner, resulting in slow cooling speed and poor cooling uniformity. For this reason, the present invention uses water mist cooling, which can obtain the best cooling effect and keep the cooling effect consistent.

Please refer to FIG. 2 , in an embodiment of the present invention, the motor casing includes a cylindrical casing 1 and a plurality of heat dissipation ribs 2 arranged on the outer periphery of the cylindrical casing 1; in order to ensure the strength and heat dissipation performance of the motor casing , the relationship between the height H of the control fins and the diameter D of the cylindrical shell is H/D=0.02～0.1; the relationship between the thickness δ of the control fins and the thickness w of the cylindrical shell is δ/w=0.05 ～0.4; the motor housing of this structure has high requirements on shape, position and size, and is difficult to extrude, and has high requirements for the consistency of cooling during cooling and quenching. Therefore, the present invention endows the profile with better extrusion performance by adjusting the formula. At the same time, the present invention adopts the cooling method of water mist cooling in the cooling stage. The water mist acts more on the heat dissipation fins 2, so that the cooling speed of each part of the motor casing is highly matched, and the shape, position and dimensional accuracy of the casing are improved.

S6: Straighten the semi-finished motor shell after cooling;

Among them, straightening can release the stress accumulated in the cooling process to a certain extent, play the role of work hardening and improve mechanical properties; but because the cross-sectional shape of the motor shell in the present invention is relatively complex, using a higher straightening amount will lead to its deformation. A large amount will affect its dimensional accuracy. Therefore, the straightening amount in the present invention is 0.2 to 1%, preferably 0.2 to 0.5%.

Preferably, after the straightening is completed, the semi-finished product of the motor housing is cut to length to determine a reasonable length.

S7: Aging treatment of the straightened semi-finished motor shell to obtain the finished aluminum profile of the motor shell;

Wherein, the aging treatment temperature is 160-180°C, and the time is 6-10h. Preferably, the aging temperature is 170-180° C., and the aging time is 7-8 hours.

In summary, through the comprehensive adjustment of the above formula and process, a motor with a tensile strength of 270 to 310 MPa, a yield strength of 240 to 270 MPa, an elongation of 15 to 20%, and a Brinell hardness of 95 to 115 N/mm ² can be obtained. Shell aluminum profile finished products.

Correspondingly, the present invention also provides a motor casing, which is prepared by the above-mentioned preparation method. Specifically, referring to FIG. 2 , in one embodiment of the present invention, the motor casing includes a cylindrical casing 1 , heat dissipation ribs 2 provided on the outer periphery of the cylindrical casing, reinforcing ribs 3 , and a cylindrical casing for supporting the cylindrical casing. The base 4 of the housing 1 .

The base 4 includes a base body 41 and a bracket 42 , and the base body 41 is connected to the cylindrical shell 1 through the bracket 42 . The bracket 42 has a hollow structure to save space and improve the heat dissipation effect. In this embodiment, a base 4 is provided on both sides of the bottom of the cylindrical shell 1 to achieve good support for the cylindrical shell 1 . In addition, the two bases 4 are axially symmetrical, so as to facilitate the design and extrusion molding of the split-flow combined die.

The reinforcing rib 3 includes a first reinforcing rib 31 and a second reinforcing rib 32, the first reinforcing rib 31 is arranged on the top of the cylindrical shell 1, and the second reinforcing rib 32 is arranged on the bottom of the cylindrical shell 1, and is located between two between the bases 4. The top of the first reinforcing rib 31 is arc-shaped, and its height is greater than the height of the heat dissipation rib 2 to prevent contact scratches. Specifically, the number of the first reinforcing ribs 31 is 2-4, and the number of the second reinforcing ribs 32 is 1-3. Preferably, the number of the second reinforcing ribs is one, and the number of the first reinforcing ribs 31 is two, which are axially symmetrically distributed, which is convenient for extrusion molding.

The distance between the heat dissipation ribs 2 is evenly distributed between the first reinforcing rib 31 and the first reinforcing rib 31 / the base 4 , and between the second reinforcing rib 32 and the base 4 . The relationship between the height H of the heat dissipation rib 2 and the diameter D of the cylindrical shell is H/D=0.02-0.1, and the relationship between the thickness δ of the heat dissipation rib and the thickness w of the cylindrical shell is δ/w=0.05-0.4. The motor shell with this proportional relationship has a large heat dissipation area, and the cylindrical shell has a high strength.

Correspondingly, the present invention also provides a motor, which includes the above-mentioned motor housing.

The present invention is further described below with specific embodiment:

Example 1

The present embodiment provides a method for preparing an aluminum profile of a motor housing, which includes:

Si 0.66%, Fe 0.23%, Cu 0.2%, Mn 0.05%, Mg 0.8%, Cr 0.05%, Zn 0.08%, Ti 0.02%, other impurities total 0.1%, the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

(3) homogenizing the aluminum ingot; wherein, the homogenizing temperature is 560°C, and the holding time is 7h;

(4) extruding the homogenized aluminum ingot to obtain a semi-finished product of the motor housing; wherein, the extrusion temperature is 520°C, and the extrusion speed is 2m/min;

(5) cooling the semi-finished product of the motor shell;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 1%;

(7) The straightened semi-finished product of the motor shell is subjected to aging treatment to obtain the finished product of the aluminum profile of the motor shell; wherein, the aging temperature is 180°C, and the aging time is 10h.

Example 2

Si 0.62%, Fe 0.18%, Cu 0.16%, Mn 0.04%, Mg 0.88%, Cr 0.07%, Zn 0.03%, Ti 0.01%, other impurities total 0.12%, the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

Specifically, the raw materials are smelted at 750-760 °C, then refined at 720 °C for 20 minutes, and then casted after standing for 20 minutes, the casting temperature is 715 °C, and the casting speed is 75 mm/min;

(3) homogenizing the aluminum ingot;

Specifically, the homogenization temperature was 560°C, and the holding time was 7.5h; after homogenization, it was first cooled to 195°C with the furnace, and then air-cooled to room temperature;

(4) extruding the homogenized aluminum ingot to obtain a semi-finished motor shell;

Specifically, the aluminum ingot is first turned and peeled, and then extruded after peeling;

During the extrusion process, the split-flow combined die was used as the mold, the mold temperature was 485 °C, the extrusion speed was 6.5 m/min, the extrusion temperature was 520 °C, and the extrusion outlet temperature was 530 °C; , it is quenched with pure nitrogen.

(5) cooling the semi-finished motor shell to 40°C;

Specifically, using water mist cooling, the air supply pressure of a single nozzle is 8bar, and the atomized water volume is 0.15L/min;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.25%;

(7) The straightened semi-finished product of the motor casing is subjected to aging treatment to obtain the finished aluminum profile of the motor casing; wherein, the aging temperature is 170°C, and the aging time is 8h.

Example 3

Si 0.64%, Fe 0.16%, Cu 0.18%, Mn 0.04%, Mg 0.9%, Cr 0.06%, Zn 0.04%, Ti 0.01%, other impurities total 0.05%, the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

Specifically, the raw materials are smelted at 750-755 °C, then refined at 710 °C for 25 minutes, and then casted after standing for 25 minutes, the casting temperature is 710 °C, and the casting speed is 70 mm/min;

(3) homogenizing the aluminum ingot;

Specifically, the homogenization temperature was 570°C, and the holding time was 7h; after homogenization, it was first cooled to 200°C with the furnace, and then air-cooled to room temperature after being released from the furnace;

During the extrusion process, the split-flow combined die was used as the mold, the mold temperature was 490°C, the extrusion speed was 6m/min, the extrusion temperature was 500°C, and the extrusion outlet temperature was 520°C; in addition, during the production process of the split-flow combined die , quenched with pure nitrogen.

(5) cooling the semi-finished motor shell to 50°C;

Specifically, using water mist cooling, the air supply pressure of a single nozzle is 6bar, and the atomized water volume is 0.2L/min;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.3%;

(7) The straightened semi-finished product of the motor shell is subjected to aging treatment to obtain the finished product of the aluminum profile of the motor shell; wherein, the aging temperature is 175°C, and the aging time is 8h.

Example 4

Si 0.62%, Fe 0.2%, Cu 0.19%, Mn 0.03%, Mg 0.86%, Cr 0.08%, Zn 0.03%, Ti 0.01%, other impurities total 0.1%, the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

Specifically, the raw materials are smelted at 750-765 °C, then refined at 720 °C for 30 minutes, and then casted after standing for 30 minutes, the casting temperature is 715 °C, and the casting speed is 60 mm/min;

(3) homogenizing the aluminum ingot;

Specifically, the homogenization temperature was 570°C, and the holding time was 7.5h; after homogenization, it was first cooled to 185°C with the furnace, and then air-cooled to room temperature;

During the extrusion process, the split-flow combined die was used as the mold, the mold temperature was 495 °C, the extrusion speed was 4.5 m/min, the extrusion temperature was 495 °C, and the extrusion outlet temperature was 510 °C; , it is quenched with pure nitrogen.

(5) cooling the semi-finished motor shell to 40°C;

Specifically, using water mist cooling, the air supply pressure of a single nozzle is 6bar, and the atomized water volume is 0.1L/min;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.4%;

Comparative Example 1

This comparative example provides a preparation method of an aluminum profile of a motor housing, which includes:

Si 0.72%, Fe 0.05%, Cu 0.25%, Mn 0.15%, Mg 1.1%, Cr 0.1%, Zn 0.25%, Ti 0.1%, other impurities total 0.1%, the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

Specifically, the raw materials are smelted at 750-760 °C, then refined at 720 °C for 30 minutes, and then casted after standing for 30 minutes, the casting temperature is 715 °C, and the casting speed is 65 mm/min;

(3) homogenizing the aluminum ingot;

Specifically, the homogenization temperature was 570°C, and the holding time was 8h; after homogenization, it was first cooled to 200°C with the furnace, and then air-cooled to room temperature after being released from the furnace;

During the extrusion process, the split-flow combined die was used as the mold, the mold temperature was 500 °C, the extrusion speed was 1.2 m/min, the extrusion temperature was 490 °C, and the extrusion outlet temperature was 510 °C; , it is quenched with pure nitrogen.

(5) cooling the semi-finished motor shell to 40°C;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.8%;

Comparative Example 2

This comparative example provides an aluminum profile for a motor housing, which is different from Example 2 in that, after extrusion, it is cooled by strong wind.

It should be noted that the extrusion dies in Examples 1 to 4 and Comparative Examples 1 to 2 are the same, that is, the design and shape of the motor housing are the same, and the specific structure can be seen in FIG. 2 . Among them, the relationship between the height H of the heat dissipation rib and the diameter D of the cylindrical shell is H/D=0.02, and the relationship between the thickness δ of the heat dissipation rib and the thickness w of the cylindrical shell is δ/w=0.08.

The aluminum profiles obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were tested; wherein, the test method for dimensional accuracy was: using a vernier caliper to measure the maximum inner diameter D _max and the minimum inner diameter D _min of the cylindrical shell , then the dimensional accuracy= _Dmin / _Dmax ×100%. The specific test results are as follows:

It can be seen from the table that the aluminum profile in the present invention has a tensile strength of ≥284MPa, a yield strength of ≥242MPa, an elongation rate of ≥15.3%, and a Brinell hardness of ≥98N/mm ² . The dimensional accuracy is ≥98.99%.

The above is the preferred embodiment of the invention, it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also regarded as protection scope of the present invention.

Claims

A preparation method for an aluminum profile of a motor shell, characterized in that it comprises:

(1) prepare raw material for subsequent use according to the proportion; wherein, the raw material formula by weight percentage is as follows:

Si 0.6～0.7%, Fe≤0.25%, Cu 0.1～0.2%, Mn≤0.05%, Mg 0.8～0.95%, Cr 0.05～0.1%, Zn≤0.1%, Ti≤0.05%, total other impurities≤0.15% , the balance is aluminum;

(2) smelting and casting the raw materials to obtain an aluminum ingot;

(3) Homogenizing the aluminum ingot; wherein, the homogenizing temperature is 550-580° C., and the holding time is 6-8 h;

(4) extruding the homogenized aluminum ingot to obtain a semi-finished motor shell; wherein, the extrusion temperature is 480-540 °C, and the extrusion speed is 2-10 m/min;

(5) cooling the semi-finished product of the motor shell;

(6) Straightening the semi-finished motor shell after cooling; wherein, the straightening amount is 0.2-1%;

(7) The straightened semi-finished product of the motor shell is subjected to aging treatment to obtain the finished product of the aluminum profile of the motor shell; wherein, the aging temperature is 160-180°C, and the aging time is 6-10h.
The preparation method of the aluminum profile of the motor shell as claimed in claim 1, is characterized in that, in step (1), the raw material formula by weight percentage is as follows:

Si 0.6～0.64%, Fe 0.05～0.25%, Cu 0.15～0.19%, Mn≤0.04%, Mg 0.84～0.9%, Cr 0.05～0.08%, Zn≤0.05%, Ti≤0.02%, total other impurities≤0.1 %, the balance is aluminum;

And Mg/Si=1.38-1.44.
The method for preparing an aluminum profile of a motor casing according to claim 1, wherein step (3) comprises:

(3.1) Homogenize the aluminum ingot at 550～580℃, and keep the temperature for 7～8h;

(3.2) The homogenized aluminum ingot is cooled to 180-200° C. with the furnace, and then cooled to room temperature after being released from the furnace.
The method for preparing an aluminum profile of a motor casing according to claim 1, wherein step (4) comprises:

(4.1) Turning the aluminum ingot after homogenization;

(4.2) The aluminum ingot after turning treatment is extruded by using a split-flow combined die; wherein, the temperature of the split-flow combined die is 480～500℃, the extrusion speed is 3～7m/min, and the extrusion temperature is 480～500℃. 525°C, the extrusion outlet temperature is 510-530°C.
The method for preparing an aluminum profile of a motor casing according to claim 1, wherein in step (5), one or two cooling methods of strong wind cooling, water mist cooling and water cooling are used to cool the motor. Shell semi-finished products are cooled;

In step (6), the straightening amount is 0.5 to 1%;

In step (7), the aging temperature is 170-180° C., and the aging time is 7-8 h.
The method for preparing an aluminum profile of a motor casing according to claim 4, characterized in that, in step (4.2), in the process of preparing the splitting combined mold, high-purity nitrogen is used to quench the splitting combined mold ;

In step (5), water mist is used to cool the semi-finished motor housing.
The method for preparing an aluminum profile of a motor casing according to claim 1, wherein step (2) comprises:

(2.1) Melting various raw materials at 700～760℃ to obtain alloy liquid;

(2.2) refining the alloy liquid at 700～730℃ for 15～30min;

(2.3) Let the refined alloy liquid stand for 20-30min;

(2.4) Cast the standing alloy liquid to obtain an aluminum ingot; wherein, the casting temperature is 700-720° C., and the casting speed is 50-80 mm/min.
The method for preparing an aluminum profile for a motor housing according to any one of claims 1, wherein the tensile strength of the aluminum profile for the motor housing is 270-310 MPa, the yield strength is 240-270 MPa, and the elongation is 15 ~20%, the Brinell hardness is 95~115N/mm 2 .
A motor casing, characterized in that it is prepared by the method for preparing an aluminum profile for a motor casing according to any one of claims 1 to 8.
A motor, characterized in that it comprises the motor housing as claimed in claim 9 .