Automobile cross beam with consideration of small offset crash safety and repairability and preparation method thereof

Abstract

A kind of automobile crossbeam of considering small offset crash safety and repairability, two middle arc regions and two edge arc regions are symmetrically arranged along its length direction, the outer convex part of middle arc region is soft region, the strength of soft region is 30%-40% of the strength of crossbeam main body, the length of soft region is L2, 30mm≤L2≤100mm;Edge arc region to the same side end of crossbeam is small offset crash corresponding area, the length of small offset crash corresponding area is L1, L is the total length of crossbeam, L1 is =0.20L-0.22L.The crossbeam described in the application sets four arc regions on the appearance structure, sets small offset crash corresponding area on the edge of crossbeam, ensures that the contact area between crossbeam and barrier is increased, and the intrusion amount of small offset crash passenger compartment is reduced under the premise of meeting the forming requirement and modeling requirement;On the basis of ensuring that crossbeam main body meets high strength requirement, set soft region in two arc regions, soft region is the part that needs to be weakened locally under specific working condition, ensures that the middle part of crossbeam is not too bent in low-speed collision, and the requirement of repair economy is well compatible.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of automobile safety components and preparation method, especially can improve the safety of 25% small offset collision of vehicle, and the economic maintenance of automobile crossbeam and preparation method. BACKGROUND

[0002] With the gradual increase of automobile ownership, the number of automobile accidents also gradually increases, and the safety of automobile in the process of collision becomes the problem that people pay more and more attention to. Under this background, in 2017, China Insurance Research officially released the small offset collision test and evaluation procedure, and formally introduced the small offset collision test evaluation in China. When the vehicle collides frontally, two longitudinal beams are the main energy-absorbing collapse components, but the area of small offset collision with the barrier is only 25% of the width of the vehicle, and the small offset collision basically avoids the longitudinal beam, and the energy during the collision is almost not blocked and directly transmitted to the passenger compartment. The front suspension, wheels and steering mechanism of the vehicle will also displace backward, and in severe cases, it may also invade the passenger compartment and cause harm to the passengers. Based on this working condition, the crossbeam is required to have sufficient strength, and the crossbeam is required to be as much as possible to extend outward relative to the longitudinal beam structure, so as to effectively transmit the collision force to the longitudinal beam and reduce the intrusion amount of the passenger compartment.

[0003] The structure of the crash beam, the repairability, the repair economy, and the vehicle compatibility of the crash beam are subdivided and evaluated in the test of the crashworthiness and repair economy of the automobile. The repairable working condition test of the automobile shows that the higher the consistency of the strength of the crossbeam is not the better, and the complete consistency of the strength of the crossbeam will produce a "V-shaped" deformation mode as shown in Figure 5 , which will damage the structure of the rear part of the crossbeam relative to the structure of the rear part of the crash beam, and the repair economy is poor. If the local strength of the crossbeam is weakened, a "straight line" deformation mode as shown in Figure 6 is produced, which will not damage the structure of the rear part of the crossbeam relative to the structure of the rear part of the crash beam, and the repair economy is good.

[0004] The structure of the high-strength steel roll pressing beam commonly seen in the market is a fixed arc. If the beam of this structure wants to adapt to the modeling requirements of the vehicle and improve the safety of small offset collision, some end reinforcing members need to be connected with the main beam through welding, riveting or bolt connection. The width direction of the beam is expanded by increasing the reinforcing members to increase the contact with the barrier during small offset collision, so as to transmit the collision force along the vehicle body direction, ensure the effective energy absorption of the vehicle body energy absorption component, and ensure the safety of the vehicle occupants. However, this structure needs to increase more reinforcing members, the tooling investment cost is high, the process is complex, and there is a risk of cracking at the welding position during collision, which affects the collision safety. Another solution is the variable curvature roll pressing technology of the beam, but the high-strength steel is limited by the material elongation and cannot realize large-angle variable curvature roll pressing. Meanwhile, the performance of the cross section of the roll-pressed beam is balanced, and the requirement of repairability cannot be met. SUMMARY

[0005] The purpose of the present application is to overcome the problems of the prior art, and to provide an automobile beam which improves the overall performance of the beam and is relatively simple in process, and which takes into account the small offset collision safety and repairability

[0006] The problem of the present application is solved by the following technical scheme:

[0007] An automobile beam which takes into account the small offset collision safety and repairability, the beam is symmetrically provided with two central arc regions and two edge arc regions along the longitudinal direction thereof, the outer convex part of the central arc region is a soft region, the strength of the soft region is 30%-40% of the strength of the main body of the beam, the length of the soft region is L2, 30mm≤L2≤100mm; the edge arc region to the same side end of the beam is a small offset collision corresponding region, the length of the small offset collision corresponding region is L1, L is the total length of the beam, L1 is =0.20L-0.22L.

[0008] The automobile beam which takes into account the small offset collision safety and repairability, the distance between the centers of the two soft regions is L3, L3 is equal to 0.19L 车 -0.21L 车 , L 车 is the width of the vehicle body.

[0009] The automobile beam which takes into account the small offset collision safety and repairability, characterized in that a transition region is distributed around the soft region, the strength of the transition region gradually increases from the soft region to the main body of the beam, and the distribution range of the transition region on the upper and lower surfaces of the beam does not exceed the center line of the beam.

[0010] The automobile beam which takes into account the small offset collision safety and repairability, the angle of the edge arc region is θ1, 90°< θ1 < 180°, and the angle of the central arc region is θ2, 90°< θ2 < 180°.

[0011] A preparation method of an automobile beam with both small offset crash safety and repairability, comprising the following steps: rolling a beam straight strip product, arc processing the straight strip product, overall heat treatment of the arc product, and local softening treatment of the arc product, wherein the overall heat treatment of the arc product is quenching and tempering treatment of the beam arc product as a whole, so that the overall tensile strength of the beam arc product is 1300-1700 MPa; the local softening treatment of the arc product is local heat treatment of the soft zone of the beam, so that the tensile strength of the soft zone is 500-800 MPa, and the elongation is greater than or equal to 10%.

[0012] The preparation method of the anti-collision beam for improving the offset crash safety and repairability of a vehicle, the local softening treatment step of the arc product is performed on a soft zone processing die, the soft zone processing die comprises an upper die and a lower die, the soft zone processing die is provided with a groove matched with the outer contour of the arc product, the lower die is provided with heating elements and temperature measuring thermocouples installed at positions corresponding to the soft zone of the arc product, cooling water channels are distributed beside the heating elements, and the cooling water channels correspond to the positions of the transition zone of the beam.

[0013] The preparation method of the anti-collision beam for improving the offset crash safety and repairability of a vehicle, the cooling water channels are arranged on the upper die at positions corresponding to the soft zone and the transition zone of the beam.

[0014] The preparation method of the anti-collision beam for improving the offset crash safety and repairability of a vehicle, in the local softening treatment step of the arc product, the soft zone of the beam arc product is locally heated to 500-600 DEG C by the electric heating elements, and then the electric heating elements are powered off, and the beam arc product is cooled to room temperature with the die.

[0015] The preparation method of the anti-collision beam for improving the offset crash safety and repairability of a vehicle, in the soft zone heating process, the cooling water channels of the upper die and the lower die are supplied with cooling water, and the temperature of the transition zone is controlled to be not higher than 200 DEG C.

[0016] The main advantages of the present application are as follows: the beam described in the present application is provided with four arc zones in the outer shape structure, and a small offset crash corresponding zone is arranged at the edge of the beam, so that the contact area between the beam and the barrier is increased, the intrusion amount of the passenger compartment in the small offset crash is reduced, and the safety performance is improved under the premise of meeting the forming and modeling requirements; on the basis of ensuring that the main body of the beam meets the high strength requirement, soft zones are arranged in two arc zones of the beam, the soft zones are parts that need to be weakened in local strength under specific working conditions, so that the middle part of the beam is not excessively bent in low-speed collision, the structure of the rear part of the anti-collision beam is not damaged, and the maintenance cost is not large, thereby the requirement of maintenance economy can be well met. The method of the present application also provides a method for preparing the beam, and the process of the method is relatively reduced, the cost is low, and the method is easy to implement. BRIEF DESCRIPTION OF DRAWINGS

[0017] The application will be further described in conjunction with the accompanying drawings.

[0018] Figure 1 is a structural schematic diagram of the cross beam described in the application;

[0019] Figure 2 is Figure 1 is a partial enlarged view at A in FIG. 1;

[0020] Figure 3 is a schematic diagram of the cross beam in use;

[0021] Figure 4 is a schematic diagram of a softening treatment mold for an arc-shaped product piece;

[0022] Figure 5 is a schematic diagram of a "V-shaped" deformation mode of the cross beam;

[0023] Figure 6 is a schematic diagram of a "straight line-shaped" deformation mode of the cross beam.

[0024] A list of reference numerals in the drawings is as follows: 1, cross beam; 2, soft zone; 3, transition zone; 4, central arc-shaped zone; 5, edge arc-shaped zone; 6, small offset impact corresponding zone; 7, center line; 8, lower mold; 9, upper mold; 10, electric heating element; 11, cooling water channel; 12, energy absorption box. DETAILED DESCRIPTION

[0025] Referring to Figures 1-3 , the cross beam 1 described in the application is a hollow structure, and the cross beam is symmetrically provided with two central arc-shaped zones 4 and two edge arc-shaped zones 5 along the length direction thereof. The angle of the edge arc-shaped zone is θ1, and 90° < θ1 < 180°. The angle of the central arc-shaped zone is θ2, and 90° < θ2 < 180°. Through the arrangement of the four arc-shaped zones, the cross beam can meet the needs of the front modeling of the automobile, i.e., the design boundary of 90° < θ < 160°, and can also ensure the molding processing without the need of adding reinforcing members. The position from the edge arc-shaped zone to the same side end of the cross beam is a small offset impact corresponding zone 6, and the length of the small offset impact corresponding zone is L1. L is the total length of the cross beam, and L1 = 0.20L - 0.22L. 车 L is the width of the vehicle body, and L = (0.7 - 0.8)L 车 . In the actual use state of the cross beam, the small offset impact corresponding zone is located outside the energy absorption box 12. The small offset impact corresponding zone extends the edge of the cross beam relative to the longitudinal beam, and can effectively transmit the impact force to the longitudinal beam, thereby reducing the intrusion amount of the passenger compartment.

[0026] Referring to Figure 1 , Figure 2In order to meet the requirements of the beam maintainability and maintenance economy, an important improvement of the beam is to set two soft areas 2 on the beam, the strength of the soft area is 30%-40% of the strength of the hard area of the beam. The soft area is located at the outer convex part of the middle arc area, the length of the soft area is L2, 30mm≤L2≤100mm. The length of the soft area is related to the stiffness of the beam, the greater the stiffness of the beam, the greater the length of the soft area. The structure of the soft area is obtained by heat treatment. The transition area 3 is distributed around the soft area, the structure of the transition area gradually transitions from the soft area to the hard area, and the strength of the transition area gradually increases from the soft area to the hard area. The soft area is set on the beam for the part that needs to be weakened in local strength under specific working conditions, so as to ensure that the middle part of the beam will not be too bent and "V-shaped" deformation will not occur in low-speed collision. However, the setting of the soft area still needs to ensure that the strength of the whole beam meets the requirements, so the range of the soft area needs to be strictly controlled. Figure 1 、 Figure 2 It can be seen that the periphery of the soft area is the transition area, the distribution range of the transition area on the upper and lower surfaces of the beam in the height direction does not exceed the center line 7 of the beam, so that the structure of other positions of the part corresponding to the soft area of the beam still maintains the strength of the hard area.

[0027] The preparation method of the beam includes the following steps: rolling the straight strip-shaped product of the beam; arc processing the straight strip-shaped product to obtain an arc product with four arc areas; overall quenching and tempering treatment of the arc product to make the whole beam reach the tensile strength of 1300-1700MPa; and local softening treatment of the arc product, which is carried out on a soft area treatment die. Referring to Figure 4 , the soft area treatment die includes an upper die 9 and a lower die 8, and the upper and lower dies are provided with grooves matched with the outer contour of the arc product. The lower die is provided with an electric heating element 10 at the position corresponding to the soft area of the arc product, and a temperature measuring thermocouple for measuring the temperature of different positions of the arc product is also installed. The heating element can be an electric heating rod, and the number of the electric heating rods is determined according to the length requirement of the soft area. In order to control the range of the soft area in a certain area, the lower die is provided with cooling water channels 11 distributed beside the heating elements, and the cooling water channels correspond to the positions of the transition area of the beam. At the same time, the upper die is also provided with cooling water channels, and the range of the cooling water channels of the upper die is not less than the range of the transition area. The arc product is placed in the lower die, the upper and lower dies are closed to cover the arc product, the electric heating element is powered on, and cooling water is introduced into the cooling water channels of the upper and lower dies. When the temperature measuring thermocouple shows 500-600℃, the temperature is maintained for 35-45s, the electric heating element is powered off, and the cooling water is stopped. The arc product of the beam is cooled to room temperature with the die. After the local softening treatment of the arc product, the tensile strength of the soft area is 500-800MPa, and the elongation is ≥10%. After the above treatment, the local strength of the soft area of the beam is weakened after being impacted, and then a "straight line type" deformation mode is generated, the intrusion amount of the beam is small relative to the rear structure of the beam, the rear structure of the beam will not be damaged, and the economic maintenance is good.

Claims

1. A vehicle cross member that balances small offset crash safety and repairability, characterized by: The beam is symmetrically provided with two middle arc-shaped areas (4) and two edge arc-shaped areas (5) along its length direction, the convex part of the middle arc-shaped area is a soft area, the strength of the soft area is 30%-40% of the main strength of the beam, the length of the soft area is L2, 30mm≤L2≤100mm; the edge arc-shaped area to the same side end of the beam is a small offset collision corresponding area, the length of the small offset collision corresponding area is L1, L is the total length of the beam, L1 is =0.20L-0.22L, L=(0.7-0.8)L 车 , the distance between the centers of the two soft areas is L3, L3 is equal to 0.19L 车 -0.21L 车 , L 车 is the width of the vehicle body; The transition zone is distributed around the soft zone, and the strength of the transition zone gradually increases from the soft zone to the main body of the beam, and the distribution range of the transition zone on the upper and lower surfaces of the beam does not exceed the center line of the beam; The local softening treatment of the arc-shaped product piece is performed on the soft zone treatment die, the soft zone treatment die includes an upper die and a lower die, the soft zone treatment die is provided with a groove matched with the outer contour of the arc-shaped product piece, heating elements and temperature measuring thermocouples are installed at positions corresponding to the soft zone of the arc-shaped product piece on the lower die, cooling water channels are distributed beside the heating elements, and the cooling water channels correspond to positions of the transition zone of the beam.

2. The vehicle cross-car beam of claim 1, wherein: The angle of the edge arc-shaped zone is θ1, 90°< θ1< 180°, and the angle of the middle arc-shaped zone is θ2, 90°< θ2< 180°.

3. A method of manufacturing a vehicle beam that satisfies both small offset crash safety and repairability according to any one of claims 1 to 2, characterized by: The method comprises the following steps: rolling the straight strip-shaped product piece of the beam, arc processing of the straight strip-shaped product piece, overall heat treatment of the arc-shaped product piece, and local softening treatment of the arc-shaped product piece. The local softening treatment of the arc-shaped product piece is performed on the soft zone treatment die, the soft zone treatment die includes an upper die and a lower die, the soft zone treatment die is provided with a groove matched with the outer contour of the arc-shaped product piece, heating elements and temperature measuring thermocouples are installed at positions corresponding to the soft zone of the arc-shaped product piece on the lower die, cooling water channels are distributed beside the heating elements, and the cooling water channels correspond to positions of the transition zone of the beam.

4. The method of claim 3, wherein the method further comprises: In the local softening treatment step of the arc-shaped product piece of the beam, the soft zone of the arc-shaped product piece of the beam is locally heated to 500-600°C by the electric heating element, and then the electric heating element is turned off, and the arc-shaped product piece of the beam is cooled to room temperature with the die. ​ 5. The method of claim 3, wherein the method further comprises: Cooling water is supplied to the cooling water channels of the upper die and the lower die during the heating process of the soft zone, so as to control the temperature of the transition zone to be not more than 200°C. ​

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