A lightweight energy-absorbing commercial vehicle rear lower protection device and a preparation method thereof

Abstract

The present invention discloses a lightweight energy-absorbing commercial vehicle rear lower protection device, comprising a crossbeam and two mounting brackets symmetrically arranged on the crossbeam; the crossbeam and the mounting brackets are both thin-walled tubular structures; the mounting brackets are configured as K-type mounting brackets and are connected to the longitudinal beam of the vehicle frame. The present invention also discloses a method for preparing a lightweight energy-absorbing commercial vehicle rear lower protection device. The present invention realizes the two functions of blocking and buffering energy absorption of the commercial vehicle rear lower protection device.

Description

Technical Field

[0001] The invention relates to the field of automobile parts manufacturing, and more specifically to a lightweight energy-absorbing commercial vehicle rear lower protection device and a preparation method thereof. Background Art

[0002] In car collision accidents, the most common and serious accidents are rear-end collisions between passenger cars and commercial vehicles, which are most likely to cause casualties. The rear underbody protection device of commercial vehicles is an important component of the passive safety protection system in rear-end collisions between passenger cars and commercial vehicles. It can effectively prevent passenger cars from drilling into the rear and lower part of the rear of commercial vehicles, and play a role in buffering and absorbing energy, thus protecting the occupants of the rear-end passenger car. Corresponding standards and regulations have been formulated both at home and abroad. China has formulated the "GB11567-2017 Requirements for Side and Rear Underbody Protection of Automobiles and Trailers" based on the European ECE regulations, and has made specific and clear provisions on the technical requirements and test conditions for the rear underbody protection device, in order to improve the passive safety and collision compatibility of automobiles, and prevent and reduce the degree of injury in accidents. At present, the rear underbody protection devices of commercial vehicles in my country mainly have the following problems:

[0003] 1) Most vehicles within the scope of the standard are not equipped with rear underbody protection devices;

[0004] 2) The installed rear underbody protection device does not meet regulatory requirements and cannot effectively prevent the passenger car from getting under the rear of the commercial vehicle. It also does not have the function of absorbing energy and reducing vibration. The reaction force generated by the collision is directly transmitted to the occupants in the passenger car, causing secondary injuries or even death.

[0005] 3) The rear underbody protection device is mainly evaluated for its blocking function using the method in Appendix B "Static Loading Test Conditions and Procedures for Rear Underbody Protection Devices" in the standard, and the buffering and energy absorption function of the rear underbody protection device is not well evaluated according to the provisions of Appendix C "Moving Barrier Rear-End Collision Test Conditions and Procedures" in the standard;

[0006] 4) The materials used for the rear underbody protection are still relatively low-end, with the mainstream using Q235 / Q345 steel, and a few using B510L~B700L steel. The crossbeam mainly adopts a rectangular tubular structure, and the mounting bracket is mainly designed by various complicated support plate structures, which are large in size and heavy in weight. Since the penalty for exceeding the limit in 2016, meeting regulatory requirements and lightweighting have become conflicting. The rear underbody protection of commercial vehicles urgently needs to introduce new structural optimization designs, advanced materials and advanced manufacturing processes. It is of great significance to design and manufacture rear underbody protection for commercial vehicles that has the characteristics of lightweight and collision energy absorption, and is easy to install and maintain.

[0007] In existing patent applications, for example, the Chinese patent authorization announcement number CN204055683U discloses a vehicle rear lower protection device that uses a buffer compression space of a connecting bracket of a closed box structure composed of two connecting brackets to buffer and absorb energy, but it still has the following defects: 1. It uses a cylindrical structure composed of two stamped parts welded together and punched pre-defects to buffer and absorb energy, and the energy absorption effect is general; 2. It does not use lightweight materials or lightweight processes with higher strength levels, and the lightweight effect is general.

[0008] Another example is the Chinese patent application publication number CN112059548 A which discloses a manufacturing process for ultra-high strength commercial vehicle front underbody protection. Although the invention can obtain commercial vehicle front underbody protection with a strength of 1300MPa to 1600MPa, it still has the following defects: 1. The overall heating and quenching of the welded small assembly makes it difficult to control deformation; 2. The overall heating and quenching of the welded small assembly and the supporting fixture wastes energy and is costly. Summary of the invention

[0009] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a lightweight energy-absorbing commercial vehicle rear lower protection device and a preparation method thereof, so as to achieve the dual functions of the commercial vehicle rear lower protection device of blocking and buffering energy absorption.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] In one aspect, a lightweight energy-absorbing commercial vehicle rear lower protection device includes a crossbeam and two mounting brackets symmetrically arranged on the crossbeam;

[0012] The crossbeam and the mounting bracket are both thin-walled tubular structures;

[0013] The mounting bracket is configured as a K-shaped mounting bracket and is connected to the longitudinal beam of the vehicle frame.

[0014] Preferably, the crossbeam and the mounting bracket are both made of hot-formed steel material;

[0015] The transverse cross-sections of the crossbeam and the mounting bracket are both rectangular.

[0016] Preferably, the mounting bracket includes a longitudinal load-bearing pipe, a vertical bracket pipe, a bevel bracket pipe and a bracket pipe;

[0017] One end of the longitudinal load-bearing pipe is welded to the crossbeam through a reinforcing plate, and the other end is welded to the lower end of the vertical support pipe;

[0018] The two ends of the bevel support tube are respectively welded to the longitudinal load-bearing pipe and the vertical support tube;

[0019] The lower end of the support tube is welded to the bevel support tube;

[0020] The upper end of the vertical support tube and the upper end of the support tube are both provided with bolt holes for arranging bolts to be connected to the longitudinal beam of the frame.

[0021] Preferably, the longitudinal load-bearing pipe comprises a first pipe and a second pipe connected in sequence;

[0022] The first pipe member and the second pipe member have different strengths;

[0023] The second pipe is welded to the crossbeam, and pre-defect grooves are formed on four corners of the outer surface of the second pipe.

[0024] Preferably, two pre-defect grooves are provided at each corner, with an interval of 20 mm to 50 mm.

[0025] On the other hand, a method for preparing the lightweight energy-absorbing commercial vehicle rear lower protection device comprises the following steps:

[0026] 1) placing the crossbeam on a coil induction heating quenching strengthening device to heat the outer electromagnetic coil of the tube, and then cooling and strengthening;

[0027] 2) placing the longitudinal load-bearing pipe on a coil induction heating quenching strengthening device, without heating the second pipe, and heating the first pipe with an electromagnetic induction coil outside the pipe, and then cooling and strengthening;

[0028] 3) placing the spliced ​​pieces formed by the plurality of beveled support tubes and the support tubes on a coil induction heating quenching strengthening device to heat the outer electromagnetic coil induction coil, cooling and strengthening, and then laser cutting to form each beveled support tube and the support tube;

[0029] 4) The longitudinal load-bearing pipe, the bevel support pipe, the support pipe and the vertical support pipe are welded to form the mounting bracket, and the two mounting brackets are welded to the crossbeam through the reinforcing plate to form the rear lower protection device of the lightweight energy-absorbing commercial vehicle.

[0030] Preferably, the temperature of the heating of the electromagnetic induction coil outside the tube is between 850°C and 950°C.

[0031] Preferably, in step 3), the method of splicing multiple pieces is as follows:

[0032] The end of the bevel support tube and the support tube with a small cutting surface is selected as the end of the splicing piece, and the end with a large cutting surface is selected as the dividing surface of the splicing piece.

[0033] Preferably, in step 4), the mounting bracket is welded by arc welding, and then connected to the crossbeam through the reinforcing plate by carbon dioxide shielded welding.

[0034] Preferably, the tensile strength of the crossbeam and the mounting bracket is ≥1500Mpa.

[0035] The invention provides a lightweight energy-absorbing commercial vehicle rear lower protection device and a preparation method thereof, which has the following beneficial effects:

[0036] 1) The lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention is mainly designed with a thin-walled tubular structure, which improves the structural rigidity; the mounting bracket is designed to be K-shaped, which has a strong blocking ability; the longitudinal load-bearing pipe is composed of two sections with different strengths, which has the dual functions of blocking and energy absorption and vibration reduction, and solves the energy absorption and buffering function that most commercial vehicle rear lower protection devices currently do not have, and can well protect the occupants in the rear-end collision of passenger cars and commercial vehicles;

[0037] 2) The lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention uses hot-formed steel for main pipes, which has lower material cost compared with conventional cold-formed ultra-high-strength steel; on the other hand, multiple pipes are spliced ​​together for heating and quenching strengthening, which can greatly improve material utilization and further reduce costs;

[0038] 3) The lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention is strengthened by electromagnetic induction coil heating and quenching, which improves the structural strength and has the characteristics of super strength and super lightness;

[0039] 4) The lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention has a simple structure, a short welding process, and strong versatility, and can be used as a standard configuration for rear lower protection of a unified platform for commercial vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention;

[0041] Figure 2 It is a schematic structural diagram of a longitudinal load-bearing pipe in a rear lower protection device of a lightweight energy-absorbing commercial vehicle according to the present invention;

[0042] Figure 3 1 is a schematic diagram of placing the crossbeam on the coil induction heating quenching strengthening device in step 1) of the method for preparing the rear lower protection device of a lightweight energy-absorbing commercial vehicle of the present invention;

[0043] Figure 4 It is a schematic diagram of placing the splicing parts on the coil induction heating quenching strengthening device in step 1) of the preparation method of the lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention, wherein (a) is a bracket tube, and (b) is a bevel bracket tube;

[0044] Figure 5 is a curve diagram of displacement-time of a mobile barrier intrusion in an embodiment of a rear lower protection device for a lightweight energy-absorbing commercial vehicle of the present invention;

[0045] Figure 6 It is a curve diagram of the internal energy of the rear lower protection-time in the embodiment of the lightweight energy-absorbing commercial vehicle rear lower protection device of the present invention. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0047] Combination Figure 1 and Figure 2 As shown, a lightweight energy-absorbing commercial vehicle rear lower protection device provided by the present invention includes a crossbeam 1 and two mounting brackets symmetrically arranged on the crossbeam.

[0048] The crossbeam 1 and the mounting bracket are both thin-walled tubular structures, both made of hot-formed steel material with the grade of 22MnB5, and both have rectangular transverse cross-sections.

[0049] The mounting bracket is configured as a K-type mounting bracket, which has a strong blocking function and is mounted on the frame longitudinal beam 7 by bolts. It is simple, convenient, and highly versatile, and can be extended to the standard configuration of rear lower protection of a unified platform for commercial vehicles.

[0050] The mounting bracket includes a longitudinal load-bearing pipe 2 , a vertical support pipe 3 , a bevel support pipe 5 and a support pipe 4 .

[0051] One end of the longitudinal load-bearing pipe 2 is welded to the crossbeam 1 through a reinforcing plate 6 , and the other end is welded to the lower end of the vertical support pipe 3 .

[0052] The two ends of the bevel support tube 5 are welded to the longitudinal bearing pipe 2 and the vertical support tube 3 respectively.

[0053] The lower end of the support tube 4 is welded to the bevel support tube 5 .

[0054] The upper ends of the vertical support tube 3 and the upper ends of the support tube 4 are both provided with a plurality of bolt holes for arranging bolts to be installed on the frame longitudinal beam 7, which is simple, convenient and highly versatile.

[0055] The longitudinal load-bearing pipe 2 includes a first pipe 21 and a second pipe 22 connected in sequence. The first pipe 21 and the second pipe 22 have different strengths and have the dual functions of blocking and absorbing energy and reducing vibration.

[0056] The end of the second pipe 22 is welded to the cross beam 1 through a reinforcing plate 6 , and two pre-defect grooves 23 are formed on four corners of the outer surface of the second pipe 22 .

[0057] The two pre-defect grooves 23 on each corner are spaced 20 mm to 50 mm apart, and play an axial compression guiding role, so that the crushing law deformation during rear-end collision plays the role of energy absorption and vibration reduction.

[0058] Combination Figure 3 and Figure 4 As shown, the present invention also provides a method for preparing a rear lower protection device for a lightweight energy-absorbing commercial vehicle, comprising the following steps:

[0059] 1) Place the crossbeam 1 on the coil induction heating quenching strengthening device, and use the propulsion device 10 to move the crossbeam 1 along the propulsion slide rail 8 toward the direction of the outer electromagnetic ring induction coil 9. The crossbeam 1 is made of hot-formed steel material with a grade of 22MnB5. The main metallographic structure at room temperature is ferrite plus carbide particles, and the tensile strength is about 600MPa. The outer electromagnetic ring induction coil 9 on the coil induction heating quenching strengthening device is heated to 850℃~950℃ to undergo austenite transformation, and then cooling water is sprayed online through the coil water spray hole for cooling and strengthening, so that the tensile strength of the crossbeam 1 reaches more than 1500MPa to achieve an ultra-strong and ultra-light pipe fitting;

[0060] 2) Place the longitudinal load-bearing pipe 2 on the coil induction heating quenching strengthening device, and use the propulsion device 10 to move the longitudinal load-bearing pipe 2 along the propulsion slide rail 8 toward the direction of the outer electromagnetic ring induction coil 9. The second pipe 22 is not heated when passing through the outer electromagnetic ring induction coil 9, so that its strength is maintained at the original strength of the material (tensile strength is about 600MPa). When the first pipe 21 reaches the outer electromagnetic ring induction coil 9, it is heated to 850℃~950℃, and then cooling water is sprayed online through the coil water spray hole for cooling and strengthening, so that its tensile strength reaches more than 1500MPa, so that the second pipe 22 and the first pipe 21 form different strength sections, which have the dual functions of blocking and energy absorption and vibration reduction;

[0061] 3) The spliced ​​parts formed by multiple beveled support tubes 5 and support tubes 4 are placed on the coil induction heating quenching strengthening device by using a multi-piece splicing method, and the longitudinal bearing pipe 2 is moved forward along the pushing slide rail 8 toward the direction of the outer electromagnetic induction coil 9 of the tube by the pushing device 10, and the outer electromagnetic induction coil of the tube is heated, and then cooled and strengthened, and then laser cutting is performed to form each beveled support tube 5 and support tube 4, which can improve material utilization and reduce manufacturing costs;

[0062] The specific number of pieces forming the splicing piece can be determined according to the table length of the coil induction heating quenching strengthening device. In order to further improve the material utilization rate, when splicing, the ends 41 and 51 with small cutting surfaces on the bevel support tube 5 and the support tube 4 are selected as the ends of the splicing piece, and the ends 42 and 52 with large cutting surfaces are selected as the dividing surfaces of the splicing piece, that is, L41≤L42, L51≤L52;

[0063] 4) The longitudinal load-bearing pipe 2, the bevel support pipe 5, the support pipe 4 and the vertical support pipe 3 are arc welded to form a mounting bracket. Both mounting brackets are welded to the crossbeam 1 through the reinforcing plate 6 by carbon dioxide shielded welding to form the rear lower protection device of the lightweight energy-absorbing commercial vehicle of the present invention. The welding is simple and the process is short.

[0064] Example

[0065] A lightweight energy-absorbing commercial vehicle rear lower protection device provided in this embodiment is installed at the rear lower protection position of a light truck, and includes a crossbeam 1 and a K-shaped mounting bracket symmetrically arranged on the crossbeam 1.

[0066] The cross beam 1 is a straight tube with a rectangular cross section and specifications of 100mm×50mm×1.4mm (length 100mm, width 50mm, tube wall thickness 1.4mm);

[0067] The cross-section of the longitudinal bearing pipe 2 and the vertical support pipe 3 is rectangular, with specifications of 80mm×40mm×1.4mm (length 80mm, width 40mm, tube wall thickness 1.4mm). The cross-section of the support pipe 4 and the bevel support pipe 5 is square, with specifications of 40mm×40mm×1.4mm (side length 40mm, tube wall thickness 1.4mm).

[0068] The longitudinal load-bearing pipe 2 includes a first pipe 21, a second pipe 22 and pre-defect grooves 23 opened on the second pipe 22. The pre-defect grooves 23 are spaced 30 mm apart and have a good axial compression guiding effect, so that they can deform according to the crushing rules during a rear-end collision and play a role in energy absorption and vibration reduction.

[0069] The crossbeam 1 and K-type mounting bracket are both made of hot-formed steel 22MnB5, and the tensile strength is ≥1500Mpa after heating and quenching strengthening by the coil induction heating and quenching strengthening device.

[0070] The lightweight energy-absorbing commercial vehicle rear lower protection device of this embodiment is 30% lighter than the original plate-shaped support structure (the original plate-shaped support structure has a mass of 15.09kg, and the lightweight and ultra-light energy-absorbing commercial vehicle rear lower protection device provided in this embodiment has a mass of 10.57kg).

[0071] According to the provisions of Appendix C "Conditions and Procedures for Mobile Barrier Rear-end Collision Test" in "GB11567-2017 Requirements for Side and Rear Underside Protection of Motor Vehicles and Trailers", the buffering energy absorption function of the rear underside protection device of the energy-absorbing commercial vehicle of this embodiment is evaluated, and the maximum penetration amount is required to be no more than 400mm.

[0072] Combination Figure 5As shown in the curve of the relationship between the drilling displacement of the mobile barrier and time, the maximum drilling amount of the original solution is 419.06 mm, which does not meet the regulatory requirements. The maximum drilling amount of the solution in this embodiment is 234.29 mm, and the drilling displacement decreases by 44.1%, which meets the regulatory requirements.

[0073] Combination Figure 6 As shown in the curve of the relationship between the internal energy of the rear lower protection and time, in this embodiment, at the beginning of the collision, the kinetic energy of the mobile barrier is quickly absorbed and converted into the deformation internal energy of the rear lower protection. In the later stage of the collision, it has sufficient blocking ability to well protect the occupants of the rear-end passenger car.

[0074] In the preparation method of the rear lower protection device of the lightweight energy-absorbing commercial vehicle in this embodiment, the method of splicing multiple pieces is as follows: the long side of the bracket tube 4 is 197.7 mm, and the short side is 145.2 mm. By adopting the splicing process, the material utilization rate can be increased by 13.3%; the long side of the bevel bracket tube 5 is 266.7 mm, and the short side is 160.3 mm. By adopting the splicing process, the material utilization rate can be increased by 19.9%.

[0075] In summary, the lightweight energy-absorbing commercial vehicle rear lower protection device and the preparation method thereof provided by the present invention achieve the dual functions of rear lower protection blocking and energy absorption buffering for commercial vehicles, avoid the reaction force from being directly transmitted to the occupants in the passenger car to cause secondary injuries or even death in the rear-end collision between a passenger car and a commercial vehicle, and well protect the occupants in the rear-end passenger car; the designed K-type tubular structure is simple and novel, has strong versatility, and is easy to install with bolts, and is suitable for promotion to the standard configuration of front and rear lower protection of the unified platform of commercial vehicles; the forming process is simple, and can achieve the technical advantage of low comprehensive cost of materials and processes.

[0076] The use of a lightweight energy-absorbing commercial vehicle rear lower protection device and its preparation method provided by the present invention can meet the requirements of regulatory tests for both blocking and energy-absorbing buffering and achieve lightweight, which can well protect the occupants in the passenger car from injury, and is the development direction of rear lower protection for commercial vehicles. The processing method of the present invention for heating, quenching, strengthening and flexible application of pipe fittings can achieve the advantages of ultra-strong, ultra-light and low cost, and can also be extended to similar tubular parts such as automobile bodies, seats, and bus bodies for application.

[0077] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing a rear lower protection device for a lightweight energy-absorbing commercial vehicle, characterized in that: The lightweight energy-absorbing commercial vehicle rear lower protection device comprises a crossbeam and two mounting brackets symmetrically arranged on the crossbeam; The crossbeam and the mounting bracket are both thin-walled tubular structures; The mounting bracket is configured as a K-shaped mounting bracket, connected to the longitudinal beam of the frame, The crossbeam and the mounting bracket are both made of hot-formed steel; The transverse cross-sections of the cross beam and the mounting bracket are both rectangular. The mounting bracket includes a longitudinal load-bearing pipe, a vertical bracket pipe, a bevel bracket pipe and a bracket pipe; One end of the longitudinal load-bearing pipe is welded to the crossbeam through a reinforcing plate, and the other end is welded to the lower end of the vertical support pipe; The two ends of the bevel support tube are respectively welded to the longitudinal load-bearing pipe and the vertical support tube; The lower end of the support tube is welded to the bevel support tube; The upper end of the vertical support tube and the upper end of the support tube are both provided with bolt holes for arranging bolts to be connected to the longitudinal beam of the frame. The longitudinal load-bearing pipe member comprises a first pipe member and a second pipe member connected in sequence; The first pipe member and the second pipe member have different strengths; The second pipe is welded to the crossbeam, and four corners of the outer surface of the second pipe are provided with pre-defect grooves. The preparation method comprises the following steps: 1) placing the crossbeam on a coil induction heating quenching strengthening device to heat the outer electromagnetic coil of the tube, and then cooling and strengthening; 2) placing the longitudinal load-bearing pipe on a coil induction heating quenching strengthening device, without heating the second pipe, and heating the first pipe with an electromagnetic induction coil outside the pipe, and then cooling and strengthening; 3) placing the spliced ​​pieces formed by the plurality of beveled support tubes and the support tubes on a coil induction heating quenching strengthening device to heat the outer electromagnetic coil induction coil, cooling and strengthening, and then laser cutting to form each beveled support tube and the support tube; 4) The longitudinal load-bearing pipe, the bevel support pipe, the support pipe and the vertical support pipe are welded to form the mounting bracket, and the two mounting brackets are welded to the crossbeam through the reinforcing plate to form the rear lower protection device of the lightweight energy-absorbing commercial vehicle.

2. The preparation method according to claim 1, characterized in that: There are two pre-defect grooves at each corner, with an interval of 20 mm to 50 mm.

3. The preparation method according to claim 1, characterized in that: The temperature of the electromagnetic induction coil outside the tube is 850°C to 950°C.

4. The preparation method according to claim 1, characterized in that: In step 3), the method of splicing multiple pieces is as follows: The end of the bevel support tube and the support tube with a small cutting surface is selected as the end of the splicing piece, and the end with a large cutting surface is selected as the dividing surface of the splicing piece.

5. The preparation method according to claim 1, characterized in that: In the step 4), the mounting bracket is welded by arc welding, and then connected to the crossbeam by carbon dioxide shielded welding through the reinforcing plate.

6. The preparation method according to claim 1, characterized in that: The tensile strength of the crossbeam and the mounting bracket is ≥1500Mpa.

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