High-performance monolithic energy-absorbing box and preparation method thereof

Abstract

The application discloses a preparation method of a high-performance integral energy-absorbing box. The integral extrusion forming process can better control the machining precision and assembly precision, and the energy-absorbing box is straightened and deformed (less than 20%) by a pre-artificial aging and a straightening machine before subsequent artificial aging, so that fine precipitated phases are introduced in advance and dislocation movement and precipitation processes in the subsequent artificial aging process are regulated, thereby greatly improving the mechanical properties of the energy-absorbing box after the subsequent artificial aging. Through the structural design of the reinforcing ribs and the crushing induction grooves of the energy-absorbing box, the strength of the energy-absorbing box itself is enhanced, and the energy-absorbing box is beneficial to crushing in the collision, thereby effectively improving the impact resistance and energy-absorbing property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile body parts, in particular to a high-performance integral energy-absorbing box and a preparation method thereof. BACKGROUND

[0002] With people paying more and more attention to the fuel efficiency and safety of automobiles, the automobile industry has an increasing demand for lightweight energy-absorbing structural parts, and the energy-absorbing box, as a main energy-absorbing structural part, is installed between the front bumper beam and the main beam. When the automobile collides, the energy-absorbing box converts the collision energy into internal energy through its elastic-plastic deformation, thereby absorbing external impact force, achieving the purpose of reducing vehicle speed, protecting passengers and vehicle safety. Therefore, the energy-absorbing box has high requirements for the comprehensive performance of aluminum alloy. First, the energy-absorbing box must have good strength, but the strength cannot be too high and must match the overall strength of the vehicle body. Second, it needs to have good plasticity and impact toughness, so that when subjected to collision impact, the energy-absorbing box can quickly deform plastically and delay fracture and crushing to improve the impact energy-absorbing effect. In addition, the energy-absorbing box also needs to be welded and assembled with the bumper beam in production, so it also needs to have good welding performance.

[0003] Heat-treatable medium-high strength aluminum alloy has the advantages of small density, large specific strength, good welding performance and easy processing, and has been widely used in energy-absorbing structural parts such as energy-absorbing boxes and front longitudinal beams in recent years, greatly reducing the weight of the vehicle body energy-absorbing structural parts and achieving lightweight. However, the strength, plasticity and impact toughness of the aluminum alloy energy-absorbing box under the existing manufacturing process are still insufficient, and when the automobile is subjected to high-speed collision in a harsh environment, it is prone to fracture and crushing, the impact energy-absorbing effect is greatly reduced, and the safety of the automobile and the driver and passengers cannot be effectively protected.

[0004] In addition, the processing method of the existing energy-absorbing box is unreasonable. At present, the more common way is to use stamping sheet metal welding to process and manufacture the energy-absorbing box, which not only causes the stress of the energy-absorbing box to be concentrated locally, making it unable to crush or deform in the expected way, resulting in a significant reduction in its energy-absorbing performance, but also lacks overall processing flow and is low in efficiency. Therefore, it is extremely important to develop an aluminum alloy energy-absorbing box that is simple and convenient to process and has high performance. SUMMARY

[0005] In view of the above deficiencies existing at present, the application provides a high-performance integral energy absorption box and a preparation method thereof. An integral extrusion forming process is adopted to better control the machining precision and assembly precision. Before subsequent artificial aging, the energy absorption box is straightened and deformed (20% or less) by pre-artificial aging and a straightening machine to introduce fine precipitated phases in advance and regulate dislocation movement and precipitation process in the subsequent artificial aging process, thereby greatly improving the mechanical properties of the energy absorption box after subsequent artificial aging. Through the structural design of the energy absorption box reinforcing ribs and the crush-inducing grooves, the strength of the energy absorption box itself is enhanced, and the energy absorption box is beneficial to crushing during a collision, thereby effectively improving its impact resistance and energy absorption.

[0006] In order to achieve the above-mentioned purpose, the application provides a preparation method of a high-performance integral energy absorption box, comprising the following steps:

[0007] Step 1: According to the "8" shaped cross-sectional shape of the extruded part required, the corresponding extrusion die is prepared, and the extrusion die is fastened on the port of the extrusion equipment;

[0008] Step 2: The aluminum alloy round bar, the extrusion die and the extrusion equipment are heated to a temperature above the solid solution temperature of the aluminum alloy round bar, and the extrusion coefficient and the extrusion speed are adjusted;

[0009] Step 3: The aluminum alloy round bar is extruded into an "8" shaped aluminum alloy profile, and is water-cooled to room temperature at the outlet of the extrusion die, and then is cut to a suitable size;

[0010] Step 4: The aluminum alloy profile cut to a suitable size is pre-aged and water-quenched to room temperature, and then is drawn to a straightening machine for room temperature straightening treatment;

[0011] Step 5: The aluminum alloy profile subjected to the straightening treatment is subjected to subsequent artificial aging and air cooling to room temperature, thereby obtaining the energy absorption box.

[0012] According to an aspect of the application, in the step 2, the temperature above the solid solution temperature of the aluminum alloy round bar is specifically a temperature of 400℃ or more above the solid solution temperature of the aluminum alloy round bar.

[0013] According to an aspect of the application, in the step 4, the temperature of the pre-artificial aging is 80-240℃, and the holding time is 10 minutes-48 hours.

[0014] According to an aspect of the application, in the step 4, the straightening treatment is a tensile treatment of 20% or less.

[0015] According to an aspect of the application, in the step 5, the temperature of the subsequent artificial aging is 80-240℃, and the holding time is 10 minutes-48 hours.

[0016] According to an aspect of the present application, the aluminum alloy round bar is an age-hardened aluminum alloy.

[0017] According to an aspect of the present application, the age-hardened aluminum alloy includes any one of 2xxx series, 6xxx series and 7xxx series.

[0018] According to an aspect of the present application, the 6xxx series includes commercial 6082 aluminum alloy.

[0019] Based on the same inventive concept, the present application also provides an energy-absorbing box prepared by the preparation method of the high-performance integral energy-absorbing box, the energy-absorbing box is an integral hollow structure, the longitudinal section of the energy-absorbing box is in the shape of "8", the energy-absorbing box further includes an intermediate layer, the intermediate layer divides the hollow structure into two cavities, and a reinforcing rib is arranged on the intermediate layer; the outer wall of the energy-absorbing box is symmetrically provided with an induction groove, and the induction groove is concave and located on both sides of the intermediate layer.

[0020] Principles of the present application:

[0021] By pre-aging and straightening deformation of the aluminum alloy extrusion material after solution-quenching and before subsequent artificial aging of the energy-absorbing box, a large number of artificial aging atomic clusters and dislocations are introduced, a part of the dislocations and the pre-artificial aging atomic clusters can be used as nucleation cores of precipitated phases in the subsequent artificial aging process, the precipitation of the main strengthening phase is promoted, the density of the precipitated phase is increased, and the size of the precipitated phase is obviously refined. The deformation of less than 20% of the straightening machine introduces movable dislocations in the energy-absorbing box to promote the efficiency and effect of the subsequent artificial aging forming, and the pre-artificial aging before deformation introduces a large number of fine precipitated phases in the energy-absorbing box to improve the performance of the energy-absorbing box and promote the subsequent artificial aging forming.

[0022] Advantages of the present application:

[0023] (1) Compared with the traditional method, the energy-absorbing box prepared by the aging forming process of the present application has a significantly improved product of strength and ductility and impact energy absorption effect, for example, the tensile strength of the 6082 aluminum alloy energy-absorbing box in examples 1-4 is more than 340 MPa, the elongation is about 10%-20%, and the impact toughness is more than 30 J·cm 2 .

[0024] (2) The integral extrusion forming process provided by the present application can further improve the forming efficiency of the aluminum alloy energy-absorbing box, facilitate the synergistic control of shape and performance, improve the performance of the aluminum alloy energy-absorbing box, and save energy. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Process flow chart of the preparation method of the high-performance integral energy-absorbing box;

[0026] Figure 2 Structure diagram of high-performance integral energy absorption box according to the present application;

[0027] Figure 3 Structure diagram of high-performance integral energy absorption box according to the present application;

[0028] BRIEF DESCRIPTION OF DRAWINGS: 1, middle layer; 2, left induction groove; 3, right induction groove. DETAILED DESCRIPTION

[0029] In order to make the present application more easily understood, the following further describes the present application in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. Obviously, the described examples are only some of the embodiments of the present application, but not all the embodiments. Based on the examples in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present application. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved in the present application can be purchased from the market or prepared by known methods.

[0030] At present, the aluminum alloy has high requirements on the comprehensive performance of the energy absorption box. First, the energy absorption box must have good strength, but the strength cannot be too high and must match the overall strength of the vehicle body. Second, it needs to have good plasticity and impact toughness, so that the energy absorption box can rapidly plastically deform and delay fracture and breakage when subjected to impact, thereby improving the impact energy absorption effect. In addition, the energy absorption box also needs to be welded and assembled with the bumper beam in production, so it also needs to have good welding performance. The strength, plasticity and impact toughness of the aluminum alloy energy absorption box under the existing manufacturing process are still insufficient, and when the vehicle is subjected to high-speed impact in a harsh environment, it is easy to produce fracture and breakage, the impact energy absorption effect is greatly reduced, and the safety of the vehicle and the driver and passengers cannot be effectively protected. In addition, the processing method of the existing energy absorption box is unreasonable, and the current common processing and manufacturing method of the energy absorption box is to use stamping sheet metal welding, which not only causes the stress of the energy absorption box to be concentrated in the local part, cannot be crushed or deformed in the expected way, and causes the energy absorption performance to be greatly reduced, but also lacks overall processing flow and is low in efficiency.

[0031] In order to solve the above problems, the application provides a high-performance integral energy absorption box and a preparation method thereof. An integrated extrusion forming process is adopted, so that the machining precision and assembly precision can be better controlled, and before subsequent artificial aging, the energy absorption box is straightened and deformed (20% or less) by pre-artificial aging and a straightening machine to introduce fine precipitated phases in advance and regulate dislocation movement and precipitation process in the subsequent artificial aging process, thereby greatly improving the mechanical properties of the energy absorption box after subsequent artificial aging. Through the structural design of the energy absorption box reinforcing ribs and the crush induction groove, not only the strength (compressive strength and yield strength) of the energy absorption box itself is enhanced, but also the crush is facilitated during the collision, thereby effectively improving the impact energy absorption performance.

[0032] As shown in Figure 1 The application provides a preparation method of a high-performance integral energy absorption box, comprising the following steps:

[0033] S01: According to the "8" shaped cross-sectional shape of the extruded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0034] S02: Heat the aluminum alloy round bar, the extrusion die and the extrusion equipment to a temperature above the solid solution temperature of the aluminum alloy round bar, adjust the extrusion coefficient and the extrusion speed;

[0035] S03: Extrude the aluminum alloy round bar into an "8" shaped aluminum alloy profile, and water cool at the outlet of the extrusion die to room temperature, and then cut to a suitable size;

[0036] S04: The aluminum alloy profile cut to a suitable size is subjected to pre-artificial aging and water quenching to room temperature, and then is drawn to a straightening machine for room temperature straightening treatment;

[0037] S05: The aluminum alloy profile subjected to the straightening treatment is subjected to subsequent artificial aging and air cooling to room temperature, and the energy absorption box is obtained.

[0038] It should be noted that the above-mentioned solid solution, water cooling and water quenching are all conventional aluminum alloy processing processes, and the application does not make too much description.

[0039] Preferably, in step 2, the temperature above the solid solution temperature of the aluminum alloy round bar is specifically a temperature of 400 DEG C or more above the solid solution temperature of the aluminum alloy round bar.

[0040] Preferably, in step 4, the temperature of the pre-artificial aging is 80-240 DEG C, and the holding time is 10 minutes-48 hours.

[0041] Preferably, in step 4, the straightening treatment is a stretching treatment of 20% or less.

[0042] Preferably, in the step 5, the subsequent artificial aging temperature is 80-240℃, and the holding time is 10 minutes-48 hours.

[0043] Preferably, the aluminum alloy round bar is an age-hardened aluminum alloy.

[0044] Preferably, the age-hardened aluminum alloy includes any one of 2xxx series, 6xxx series and 7xxx series.

[0045] It should be noted that 2xxx series, 6xxx series and 7xxx series are all alloys that can be strengthened by heat treatment. The energy absorption box prepared by the preparation method of the present application can significantly improve the product of strength and plasticity and the impact energy absorption effect compared with the energy absorption box prepared by the traditional method.

[0046] Preferably, the 6xxx series includes commercial 6082 aluminum alloy.

[0047] Preferably, the present application also provides an energy absorption box prepared by the preparation method of any high-performance integral energy absorption box. Figures 2-3 As shown in the figure, the energy absorption box is a one-piece hollow structure, the longitudinal section of the energy absorption box is in the shape of "8", the energy absorption box further includes an intermediate layer 1, the intermediate layer 1 divides the hollow structure into two cavities, and a reinforcing rib is arranged on the intermediate layer 1; the outer wall of the energy absorption box is symmetrically provided with an induction groove, and the induction groove is concave and located on both sides of the intermediate layer 1, respectively.

[0048] It should be noted that the induction groove includes a left induction groove 2 and a right induction groove 3; the reinforcing rib is protruding on the intermediate layer 1, Figures 2-3 The reinforcing rib is not shown in the figure.

[0049] Preferably, the tensile strength of the energy absorption box is above 340MPa, the elongation is 10%-20%, and the impact toughness is 30J·cm 2 The above.

[0050] It should be noted that the aluminum alloy round bar of the embodiments 1-4 and the comparative example 1 of the present application is a commercial 6082 aluminum alloy.

[0051] It should be noted that the energy absorption boxes prepared by the embodiments 1 and the comparative example 1 are detected for tensile strength, yield strength and elongation after fracture. Specifically, the aluminum alloy energy absorption boxes manufactured by the embodiments 1-4 and the comparative example 1 are taken at the same position, and are processed into standard tensile specimens according to the standard GB / T228-2002. The room temperature tensile test is carried out on a 100-KNMTS tensile machine, the tensile rate is 2mm / min, and the tensile strength, yield strength and elongation after fracture of the energy absorption box are detected.

[0052] It should be noted that the impact toughness is a representation of the energy absorption box under the action of impact load to resist deformation and fracture, and reflects its resistance to external impact load. The impact toughness of the energy absorption box prepared in Example 1 and Comparative Example 1 is detected, which is: the aluminum alloy energy absorption boxes manufactured in Examples 1-4 and Comparative Example 1 are taken at the same position, and the standard samples are processed according to the standard HB5144-1980, and the room temperature impact test is carried out on the PYM-100 type impact testing machine to detect the impact toughness value of the energy absorption box.

[0053] The following will be exemplarily described in combination with the aluminum alloy round bar of a specific material.

[0054] Example 1

[0055] A preparation method of a high-performance integral energy absorption box:

[0056] Step 1: according to the "8" shaped cross-section shape of the extrusion molded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0057] Step 2: heat the 6082 aluminum alloy round bar to a solid solution temperature above 400℃, heat the die and the extrusion cylinder to above 400℃, adjust the extrusion coefficient and the extrusion speed;

[0058] Step 3: extrude the aluminum alloy round bar into an aluminum alloy extrusion profile with a "8" shaped cross-section, water cool the aluminum alloy extrusion profile to room temperature at the outlet of the extrusion die, and cut to a suitable size;

[0059] Step 4: heat the aluminum alloy extrusion profile cut to a suitable size to 150℃ and pre-aging for 1 hour, then water quench to room temperature, and deform the aluminum alloy extrusion profile by 10% in the straightening machine at room temperature;

[0060] Step 5: then after subsequent artificial aging at 150℃ for 12 hours and air cooling to room temperature, the aluminum alloy energy absorption box is obtained.

[0061] Example 2

[0062] A preparation method of a high-performance integral energy absorption box:

[0063] Step 1: according to the "8" shaped cross-section shape of the extrusion molded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0064] Step 2: heat the 6082 aluminum alloy round bar to a solid solution temperature above 400℃, heat the die and the extrusion cylinder to above 400℃, adjust the extrusion coefficient and the extrusion speed;

[0065] Step 3: extruding the aluminum alloy round bar into an aluminum alloy extrusion profile with a "8" shaped cross section, water cooling the aluminum alloy extrusion profile at the outlet of the extrusion die to room temperature, and cutting to a suitable size;

[0066] Step 4: heating the aluminum alloy extrusion profile cut to a suitable size to 120℃ and pre-aging for 12 hours, then water quenching to room temperature, deforming the aluminum alloy extrusion profile by 10% at room temperature in a straightening machine;

[0067] Step 5: then after subsequent aging at 150℃ for 12 hours and air cooling to room temperature, obtaining the aluminum alloy energy absorption box.

[0068] Example 3

[0069] A method for preparing a high-performance monolithic energy absorption box:

[0070] Step 1: according to the "8" shaped cross section shape of the extruded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0071] Step 2: heating the 6082 aluminum alloy round bar to a solid solution temperature above 400℃, heating the die and the extrusion cylinder to above 400℃, adjusting the extrusion coefficient and the extrusion speed;

[0072] Step 3: extruding the aluminum alloy round bar into an aluminum alloy extrusion profile with a "8" shaped cross section, water cooling the aluminum alloy extrusion profile at the outlet of the extrusion die to room temperature, and cutting to a suitable size;

[0073] Step 4: heating the aluminum alloy extrusion profile cut to a suitable size to 180℃ and pre-aging for 10 minutes, then water quenching to room temperature, deforming the aluminum alloy extrusion profile by 10% at room temperature in a straightening machine;

[0074] Step 5: then after subsequent aging at 120℃ for 48 hours and air cooling to room temperature, obtaining the aluminum alloy energy absorption box.

[0075] Example 4

[0076] A method for preparing a high-performance monolithic energy absorption box:

[0077] Step 1: according to the "8" shaped cross section shape of the extruded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0078] Step 2: heating the 6082 aluminum alloy round bar to a solid solution temperature above 400℃, heating the die and the extrusion cylinder to above 400℃, adjusting the extrusion coefficient and the extrusion speed;

[0079] Step 3: extruding the aluminum alloy round bar into an aluminum alloy extrusion profile with a "8" shaped cross section, water cooling the aluminum alloy extrusion profile at the outlet of the extrusion die to room temperature, and cutting to a suitable size;

[0080] Step 4: heating the aluminum alloy extrusion profile cut to a suitable size to 120℃ and pre-aging for 12 hours, then water quenching to room temperature, deforming the aluminum alloy extrusion profile by 5% at room temperature in a straightening machine;

[0081] Step 5: then after subsequent aging at 120℃ for 24 hours and air cooling to room temperature, obtaining the aluminum alloy energy absorption box.

[0082] Comparative Example 1

[0083] A method for preparing a high-performance monolithic energy absorption box:

[0084] Step 1: according to the "8" shaped cross section shape of the extruded part required, prepare the corresponding extrusion die, and fasten the extrusion die on the port of the extrusion equipment;

[0085] Step 2: heating the 6082 aluminum alloy round bar to a solid solution temperature above 400℃, heating the die and the extrusion cylinder to above 400℃, adjusting the extrusion coefficient and the extrusion speed;

[0086] Step 3: extruding the aluminum alloy round bar into an aluminum alloy extrusion profile with a "8" shaped cross section, water cooling the aluminum alloy extrusion profile at the outlet of the extrusion die to room temperature, and cutting to a suitable size;

[0087] Step 4: heating the aluminum alloy extrusion profile cut to a suitable size to 180℃ and pre-aging for 3 hours, then air cooling to room temperature, obtaining the aluminum alloy energy absorption box.

[0088] Performance detection

[0089] The aluminum alloy energy absorption boxes prepared in Examples 1-4 and Comparative Example 1 were subjected to mechanical property detection, and the results are shown in Table 1; the aluminum alloy energy absorption boxes prepared in Examples 1-4 and Comparative Example 1 were subjected to impact toughness value detection, and the results are shown in Table 2:

[0090] Table 1 Mechanical properties of the aluminum alloy energy absorption boxes prepared in Examples 1-4 and Comparative Example 1 (unit: MPa)

[0091] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Yield strength 355 347 337 317 315 Tensile strength 357 351 347 340 330 Elongation 12.1％ 15.3％ 14.9％ 18.7％ 9.5％

[0092] Table 2 Impact toughness values of the aluminum alloy energy absorption boxes prepared in Examples 1-4 and Comparative Example 1 (unit: J·cm 2 )

[0093] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Impact toughness values 30.1 31.5 31.1 35.2 24.3

[0094] From Table 1, it can be seen that the tensile strength, yield strength and elongation at break of the energy absorption box prepared in Examples 1-4 of the present application are simultaneously improved relative to Comparative Example 1; from Table 2, it can be seen that the energy absorption box prepared in Examples 1-4 of the present application can keep the impact toughness at 30 J·cm 2 The above.

[0095] The above is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a high-performance integral energy-absorbing box, characterized in that, Includes the following steps: Step 1: Prepare the corresponding extrusion die according to the figure-eight cross-sectional shape of the required extruded part, and fasten the extrusion die to the port of the extrusion equipment; Step 2: Heat the aluminum alloy round bar, extrusion die, and extrusion equipment to a temperature above the solution temperature of the aluminum alloy round bar, and adjust the extrusion coefficient and extrusion speed; wherein, the temperature above the solution temperature of the aluminum alloy round bar is specifically a temperature above 400°C. Step 3: Extrude the aluminum alloy round bar into an "8" shaped aluminum alloy profile, and cool it to room temperature with water at the exit of the extrusion die, and then cut it to the appropriate size; Step 4: The aluminum alloy profiles cut to the appropriate size are pre-aged artificially and then water-quenched to room temperature. They are then drawn to a straightening machine for room temperature straightening. The pre-aging temperature is 80-240℃, and the holding time is 10 minutes to 48 hours. The straightening process is a 10-20% stretching treatment. Step 5: The straightened aluminum alloy profile is then subjected to subsequent artificial aging and air-cooled to room temperature to obtain the energy-absorbing box; wherein the subsequent artificial aging temperature is 80-240℃ and the heat preservation time is 10 minutes-48 hours.

2. The method for preparing the high-performance integral energy-absorbing box according to claim 1, characterized in that, The aluminum alloy round bar is an age-hardening aluminum alloy.

3. The method for preparing the high-performance integral energy-absorbing box according to claim 2, characterized in that, The age-hardening aluminum alloys include any one of the 2xxx series, 6xxx series, and 7xxx series.

4. The method for preparing the high-performance integral energy-absorbing box according to claim 3, characterized in that, The 6xxx series includes commercially available 6082 aluminum alloy.

5. An energy-absorbing box prepared by the method of any one of claims 1-4, characterized in that, The energy-absorbing box is an integral hollow structure with a longitudinal section in the shape of an "8". The energy-absorbing box also includes an intermediate layer that divides the hollow structure into two cavities. The intermediate layer is provided with reinforcing ribs. The outer wall of the energy-absorbing box is symmetrically provided with induction grooves, which are recessed and located on both sides of the intermediate layer.

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