Method for improving strength of 1370 aluminum alloy extruded busbar to meet H24 state

Abstract

The invention discloses a method for improving the strength of a 1370 aluminum alloy extruded busbar to meet the H24 state, which comprises the following steps: S1, preparing an aluminum rod: smelting an alloy by adopting a continuous casting and rolling process, wherein the alloy comprises the following components in percentage by weight: 0.04-0.07% of Si, 0.14-0.16% of Fe, less than or equal to 0.02% of single other impurities, less than or equal to 0.10% of total impurities and the balance of Al; in the smelting process, the hydrogen content is controlled to be smaller than or equal to 0.12 ml / 100 gAl, and an aluminum rod with the diameter being 15 mm is cast; s2, extrusion forming is conducted, specifically, a 400 model continuous extruder is used for extruding an aluminum rod into a busbar with the width being 18 mm and the thickness being 5 mm, the extrusion speed is 20-25 m / min, and the technological process comprises unwinding and straightening, brushing, extrusion, cooling and winding; and S3, cold rolling strengthening is conducted, specifically, the extruded mother row is coiled and rolled through a cold rolling mill, and the rolling reduction is 7%-12% of the thickness, preferably 7%. By optimizing the extrusion process parameters and the cold rolling reduction, the problems of insufficient strength and slitting burrs of a traditional extrusion process are solved, consideration of H24-state high strength and qualified R angles is achieved, and the method is suitable for manufacturing the lightweight conductive busbar of the new energy automobile.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing conductive busbars for new energy vehicles, and in particular to a method for improving the strength of a 1370 aluminum alloy extruded busbar to meet the H24 state. Background Art

[0002] With the rapid development of the new energy industry, new energy vehicles are increasingly popular among consumers. Compared to traditional fuel vehicles, new energy vehicles use batteries instead of gasoline, making them more environmentally friendly and energy-efficient. New energy vehicles rely on batteries to transmit power to various components. The product that provides the medium for power transmission is called a conductive busbar. Traditionally, busbars are made of copper, but with the trend towards lightweight vehicles, aluminum has become the preferred material for many automakers, leading to the increasing use of aluminum in conductive busbars.

[0003] Aluminum busbars currently primarily use 1-series and 6101 aluminum alloys, with 1370 aluminum alloy being widely used due to its high electrical conductivity. To prevent electrical leakage, the surface of the aluminum busbars must be coated with an insulating layer through extrusion. The traditional production process for 1370 / H24 aluminum busbars involves rolling a wide aluminum coil, then performing a low-temperature heat treatment. Once the coil reaches the H24 state, it is then slit into the desired width. This process achieves high strength, but the edges of the slit products may have burrs, hindering extrusion. Extrusion can completely eliminate burrs and allow for smooth R-angles of varying sizes to be created through die casting. However, the extrusion process typically involves high temperatures exceeding the recrystallization temperature of the aluminum alloy, resulting in an H112 state, which is weaker than the H24 state. Summary of the Invention

[0004] The present invention provides a method for improving the strength of a 1370 aluminum alloy extruded busbar to meet the H24 state.

[0005] A method for improving the strength of a 1370 aluminum alloy extruded busbar to meet the H24 state comprises the following steps:

[0006] S1. Aluminum Rod Preparation: Continuous casting and rolling processes are used to melt the alloy, with the composition by weight being 0.04-0.07% Si, 0.14-0.16% Fe, and the remaining impurities being ≤0.02% individually and ≤0.10% in total, with the balance being Al. During the melting process, the hydrogen content is controlled to ≤0.12ml / 100gAl, and aluminum rods with a diameter of 15mm are cast.

[0007] S2. Extrusion molding: Use a 400 model continuous extruder to extrude the aluminum rod into a busbar with a width of 18 mm and a thickness of 5 mm. The extrusion speed is 20-25 m / min. The process flow is unwinding and straightening, cleaning and brushing, extrusion, cooling, and winding;

[0008] S3. Cold rolling strengthening: The extruded busbar is coiled and rolled through a cold rolling mill with a reduction of 7% to 12% of the thickness, preferably 7%.

[0009] Preferably, the cold rolling reduction should not exceed 12% to avoid unqualified R angle.

[0010] Preferably, the extruder model is a 400-type continuous extruder.

[0011] Preferably, the hydrogen content of the aluminum rod is controlled to be 0.08-0.11 ml / 100 gAl.

[0012] Preferably, the extrusion step further includes an online degassing process, and the hydrogen content of the aluminum liquid after degassing is ≤0.09ml / 100gAl.

[0013] Preferably, the cold rolling step further includes an annealing treatment, the annealing temperature is 250-300° C., and the holding time is 1-2 hours.

[0014] Preferably, the cooling step adopts a combination of water cooling and air cooling, with the water temperature controlled at 20-30° C. and the wind speed at 5-8 m / s.

[0015] Preferably, the final thickness of the extruded busbar is 4.65-4.75 mm, and the width tolerance is ≤±0.1 mm.

[0016] Compared with the existing technology, the beneficial effects of the present invention are: by optimizing the extrusion process parameters and the cold rolling reduction, the problems of insufficient strength and slitting burrs in the traditional extrusion process are solved, and the high strength of the H24 state and the qualified R angle are achieved. It is suitable for the manufacture of lightweight conductive busbars for new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A chart showing the chemical composition of aluminum rods.

[0018] Figure 2 Schematic diagram of the cold rolling process.

[0019] Figure 3 Schematic diagram of R angle position. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below.

[0021] Example 1

[0022] Aluminum rods are melted according to the formula. The chemical composition of the aluminum rods (weight percentage) is: Si: 0.05%, Fe: 0.15%, Cu: 0.005%, Mn: 0.008%, Mg

[0023] :0.009%, Cr:0.007%, Zn:0.002%, V:0.001%, Na:0.001%, Ti:0.001%, Ca:0.001%, Li:0.001%, B:0.001%, Al: balance. A 15mm diameter aluminum rod was cast with a hydrogen content of 0.10ml / 100g Al. A 400 continuous extruder was used at an extrusion speed of 25m / min. The process involved unwinding and straightening, brushing, extrusion, cooling, and coiling. After coiling, cold rolling was performed (Figure 2) with a 7% reduction.

[0024] After testing: tensile strength: 152MPa, yield strength: 135MPa, elongation: 8.2%, R angle size (such as Figure 3 ): 0.45mm, surface quality: no burrs, meeting the requirements of extrusion process.

[0025] Example 2

[0026] Aluminum rods are melted according to the formula. The chemical composition of the aluminum rods (weight percentage) is: Si: 0.06%, Fe: 0.14%, Cu: 0.003%, Mn: 0.005%, Mg

[0027] :0.007%, Cr:0.009%, Zn:0.001%, V:0.002%, Na:0.001%, Ti:0.001%, Ca:0.001%, Li:0.001%, B:0.001%, Al: balance. The smelting process was the same as in Example 1, with the aluminum rod containing 0.11 ml of hydrogen per 100 g of Al. The extruder parameters were adjusted to an extrusion speed of 22 m / min, with all other processes remaining unchanged. The cold rolling reduction was increased to 10%.

[0028] Test results: tensile strength: 155MPa, yield strength: 138MPa, elongation: 7.8%, R angle size: 0.48mm, surface quality: slight orange peel texture (does not affect the adhesion of the insulation layer).

[0029] Example 3

[0030] Aluminum rods were melted according to the following formula: chemical composition (by weight): Si: 0.04%, Fe: 0.16%, Cu: 0.002%, Mn: 0.003%, Mg: 0.006%, Cr: 0.005%, Zn: 0.001%, V: 0.001%, Na: 0.001%, Ti: 0.001%, Ca: 0.001%, Li: 0.001%, B: 0.001%, Al: balance. The melting process was the same as in Example 1, with a hydrogen content of 0.09 ml / 100 g Al. The extrusion speed was reduced to 20 m / min, and the cold rolling reduction was controlled at 12%. Test results: tensile strength: 158 MPa, yield strength: 142 MPa, elongation: 7.5%, R-angle dimension: 0.50 mm, and surface quality: minor scratches (which can be eliminated by polishing).

[0031] The present invention solves the problems of insufficient strength and slitting burrs in traditional extrusion processes by optimizing extrusion process parameters (speed 20-25m / min) and cold rolling reduction (7%-12%), achieving both high strength in the H24 state and a qualified R angle, and is suitable for the manufacture of lightweight conductive busbars for new energy vehicles.

[0032] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and it is intended that all changes that come within the meaning and range of equivalents of the claims be included therein.

[0033] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method includes only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state, characterized in that: The following steps are involved: S1. Aluminum rod preparation: Continuous casting and rolling processes are used to melt the alloy, with the composition by weight being 0.04-0.07% Si, 0.14-0.16% Fe, and the remaining impurities being ≤0.02% individually and ≤0.10% in total, with the balance being Al. During the melting process, the hydrogen content is controlled to be ≤0.12ml / 100gAl, and aluminum rods with a diameter of 15mm are cast. S2. Extrusion molding: Use a 400 model continuous extruder to extrude the aluminum rod into a busbar with a width of 18 mm and a thickness of 5 mm. The extrusion speed is 20-25 m / min. The process flow is unwinding and straightening, cleaning and brushing, extrusion, cooling, and winding; S3. Cold rolling strengthening: The extruded busbar is coiled and rolled through a cold rolling mill with a reduction of 7% to 12% of the thickness, preferably 7%.

2. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The cold rolling reduction should not exceed 12% to avoid unqualified R angle.

3. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The extruder model is a 400-type continuous extruder.

4. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The hydrogen content of the aluminum rod is controlled to be 0.08-0.11 ml / 100 gAl.

5. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The extrusion step also includes an online degassing process, and the hydrogen content of the aluminum liquid after degassing is ≤0.09ml / 100gAl.

6. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The cold rolling step also includes an annealing treatment, the annealing temperature is 250-300° C., and the holding time is 1-2 hours.

7. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The cooling step adopts a combination of water cooling and air cooling, with the water temperature controlled at 20-30° C. and the wind speed at 5-8 m / s.

8. The method for improving the strength of 1370 aluminum alloy extruded busbar to meet H24 state according to claim 1, characterized in that: The final thickness of the extruded busbar is 4.65-4.75 mm, and the width tolerance is ≤±0.1 mm.

Images