KR20070022396A - Vehicle bumper having non-uniform cross section - Google Patents

Abstract

The bumper beam for a vehicle according to the present invention includes a tubular beam having an empty interior, and includes two side rail mounting portions and a front impact portion formed between the side rail mounting portions and a mounting portion located therebetween. The front impact region includes an impact region and two additional deformation regions, the initial impact region being located between the additional deformation regions. The initial impact area generally has a flat top and bottom, and each of the additional deformation regions generally has a convex top and bottom.

Vehicle, bumper, beam, impact

Description

VEHICLE BUMPER HAVING NON-UNIFORM CROSS SECTION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to bumper beams of motor vehicles, and more particularly to bumper beams for motor vehicles formed of a hollow tublar.

BACKGROUND [0002] Motor vehicles typically include bumpers and also include fascia as a cover located outside the bumper to improve the appearance and / or aerodynamic properties of the vehicle. The vehicle bumper is designed to absorb low speed impact energy to avoid damage to other parts of the vehicle. Thus, if such a collision occurs, repair costs can be reduced since only bumpers and fascia need to be replaced. The space between the fascia and the bumper is typically filled with foam.

For example, in a slow impact of about 5 miles per hour, the bumper would be expected to absorb the amount of energy applied. The amount of energy absorbed (e) will be defined by the vehicle's mass (m) and speed (v) according to the formula 'e = (0.5) (m) (v ² )'. Thus, in a test of a given vehicle at a given speed, the energy absorbed (energy to the extent of stopping the vehicle) will be constant. The energy absorbed by the bumper is the "stroke" (s) as the distance traveled after the vehicle touches the test barrier and before it stops, according to a formula such as 'e = (F) (s)'. And is a function of the force (F) applied to stop the vehicle. Therefore, greater force and less distance may correspond to energy absorption at less force and greater distance. However, if the force is too large, excess energy is transmitted to the vehicle's frame causing loss, and if the distance is too large, losses can occur in parts of the vehicle except the bumper. Thus, force and distance must be balanced, and vehicle manufacturers set standard values for both force and distance of a given vehicle. These requirements are defined here as "performance requirements."

One factor that may affect bumper performance is the moment of inertia I _A at various points located along the bumper beam. The moment of inertia is a measure of the rigidity and stiffness of the structural member. In a certain amount of a particular type of material, the moment of inertia at a point is a function of the cross-sectional shape of the structure at that point. At a force applied perpendicular to the surface of a portion of the solid rectangle, the moment of inertia I _A = (a ³ xb) / 12. Where a is the depth of the rectangle in the direction in which the force is applied, and b is the height of the rectangle in the direction orthogonal to the direction in which the force is applied. In a solid cylinder, the moment of inertia I _A = (π xr ⁴ ) / 4. Where r is the radius. In a hollow cylinder, the moment of inertia I _A = (π x (a ⁴ -b ⁴ )) / 4. Where a is the outer diameter of the cylinder and b is the inner diameter of the cylinder. In complex shapes, the calculation of the moment of inertia is more complicated. The greater the moment of inertia, the greater the resistance to bending forces.

In addition, the bumper must also meet the "layout requirement" to meet the performance requirements. In other words, the bumper should be able to be securely mounted to the side rails of the vehicle, and the position and relative arrangement of the side rails may vary depending on the type of vehicle. Moreover, the bumper is required to be fitted between the ends of the side rails and to the underside and the rear of the vehicle fascia, so there is a restriction imposed on the dimensions of the bumper. In addition, the vehicle manufacturer may set weight requirements and cost requirements for the bumper.

[0006] Bumpers have traditionally been produced by roll forming, such as metal forming using contoured rolls. When a roll forming process is used to form the bumper, the metal sheet is bent to the designed shape, where the long ground edges are welded together. The bumper produced by the roll forming process is formed from a continuous sheet of metal, which is cut into a suitable size while being produced in a continuous and generally curved tubular shape in the manufacturing process. Therefore, when roll forming is used for bumper manufacture, it will typically have a constant radius of curvature throughout the bumper. In other words, the radius of curvature of the theoretical center of mass path through the tube will be constant at the position defined by the path where the theoretical center of mass path will lie above any center point of the vertical cross-sectional area taken at any point on the bumper element. Additionally, roll forming alone produces bumpers with a constant cross-sectional area, generally without further manufacturing processes. Having such a constant radius of curvature and a constant cross sectional area is a limitation in the bumper design. As a result, the bumper manufactured by roll forming may not have the design flexibility necessary to meet at least one of the performance requirements and layout requirements of modern automobiles.

[0007] U.S. Patent Application 6,349,521 discloses a bumper beam including a precise center having different radii as a hydroformed bumper beam having a non-uniform cross-sectional area in the front wall and the rear wall. . This type is known to produce bumper beams with high energy absorption but with a central flow.

However, there is a need for a bumper beam having a shaped impact area to optimize the performance of a bumper that absorbs energy in low speed collisions without causing structural damage to the vehicle.

In one aspect, the present invention relates to a vehicle bumper comprising a beam formed from a hollow tublar with a longitudinally curved interior. These beams are formed continuously with two side rail mountings and side rail mountings and comprise a front impact portion located between them. The front impact portion includes an initial impact region and two additional deformation regions. The initial impact region is located between the additional strain regions. The initial impact area generally has a flat top and bottom, and the additional deformation areas generally have a convex top and bottom, respectively.

The top surface of the initial impact region and the top surface of the additional deformation regions preferably each comprise areas of a single continuous top surface of the front impact portion, and the bottom of the initial impact region and the bottom surface of the additional deformation regions preferably each front impact It includes areas of a single continuous bottom of negative. The top and bottom surfaces of the front impact portion preferably taper gently from generally flat in the initial impact region to generally convex in the additional deformation regions. The bumper may have a front surface that includes a stiffening channel extending at least along the front impact portion of the front surface.

The initial impact area of the bumper has a minimum moment of inertia related to the impact direction, and the additional deformation regions each have a maximum moment of inertia related to the impact direction. The minimum moment of inertia of the original impact region is greater than the maximum moment of inertia of each of the additional deformation regions.

In a preferred embodiment, the bumper beam theoretically has a center of mass path by having a center point, the front impact portion being maximum at a point corresponding to the center point and minimum at the end of the additional deformation regions proximate the side rail mounts. It has a moment of inertia related to the direction of impact. At this time, the moment of inertia generally decreases continuously from the point corresponding to the center point to the two ends of the additional deformation regions.

The bumper beam preferably has an outer surface composed of super rigid steel and having a constant perimeter. The theoretical center of mass path through the tubular beam may have a non-uniform radius of curvature in the direction of impact.

In yet another aspect, the present invention relates to a vehicle bumper comprising a tubular beam having a top surface and a bottom surface, having a first and second ends, having a first and second ends, and having a hollow interior in a longitudinal direction. Each of the top and bottom surfaces has a generally flat area located at the center of the bumper relative to the first and second ends. The top and bottom surfaces also have a second convex region located between the second end and the center portion, and a first convex region located between the first end and the center portion, respectively. The first and second convex regions on the top surface taper gently to generally flat regions on the top surface, and the first and second convex regions on the bottom surface may gently taper to generally flat regions on the bottom surface.

1 to 4, a bumper 10 according to a preferred embodiment of the present invention is shown. The bumper 10 includes a longitudinally curved tubular beam 12 having an empty interior comprising two side rail mounting portions 14 and a front impact portion 16. The front impact portion 16 is located between the side rail mountings 14 and is subsequently formed. When mounted to the vehicle, the bumper 10 is located behind the fascia 50 (see FIG. 4) and will be covered by the fascia 50. Preferably, the side rail mounting portions 14 are located at the ends 17 of the tubular beam 12.

The front impact portion 16 includes an initial impact region 18 and two additional deformation regions 20. The initial impact zone 18 is located midway between the additional deformation zones 20 and although it is indirect contact because it is located behind the fascia 50, the first part of the bumper that comes in contact with the obstacle during a frontal collision is Will be. The additional deformation zones 20 are located between the side rail mountings 14 and the initial impact zone 18, when all energy is absorbed and the vehicle stops as the vehicle continues to move forward during the collision. It will deform while absorbing energy.

Bumper 10 is preferably formed by a hydroforming process, preferably formed of a round welded steel tube. More preferably, the welded steel tube is produced by electrical resistance welding (ERW). Such tubes preferably comprise ultra high strength steel (UHSS), in particular in embodiments of the invention, having an outer diameter of 100 mm and a thickness of 1.0 mm to 2.0 mm. The tube is placed on a die used for hydroforming, bent to size if necessary, and hydroformed to the shape described above. The hydroforming process is described in more detail below.

Referring to FIG. 5, the bumper 10 theoretically has a centering yell path 22 and the theoretical center of mass path 22 can be placed on any center point 24 of the vertical section taken at any position on the bumper. It is defined as a path. The center points of such a vertical cross section are represented, for example, by the center points 24a to 24l and the overall center point 26, with each center point being spaced 0.1 m apart. The front impact 16 is theoretically centered around the overall center point 26 of the center of mass path 22.

The bumper 10 is preferably bilaterally symmetric in the longitudinal direction along the theoretical center of mass path 22, and consequently a bumper extending longitudinally along the theoretical center of mass path 22 from the overall center point 26. The two halves of 10 are mirror images of each. It will be appreciated that the individual vertical cross sections of the bumper are not symmetrical.

Referring to FIG. 5, the front impact portion 16 is approximately 0.8 m long and this length is theoretically measured along the center of mass path 22. The initial impact 18 is approximately 0.1 m long and each of the additional deformation regions 20 is approximately 0.35 m long, which is theoretically measured along the center of mass path 22. Of course, one of ordinary skill in the art will recognize that these figures are merely illustrative of one preferred embodiment, and that numerous other embodiments, including other figures, are encompassed within the scope of the present invention. For example, modifications of such values may be necessary to apply the bumper 10 to vehicles of various sizes and types.

5 and the above description, the bumper 10 is preferably symmetric in the longitudinal direction. 5 shows the cross-sectional position of the bumper 10 taken at 0.1 m intervals. Since the bumper 10 is symmetric in the longitudinal direction, representative cross-sectional areas are taken along one longitudinal half of the bumper 10. The cross-sectional areas are the vertical sections through which the center points '24a' through '24f' and the overall center point 26 pass, and are orthogonal to the theoretical center of mass path at the intersection. 6 to 12 these cross sectional areas are shown to represent the shape of the bumper 10. 6-10 show the cross-sectional areas of the half of the front impact portion 16 which are symmetrical, and FIG. 6 shows the cross-sectional area through which the overall center point 26 passes and shows the shape of the preferred embodiment of the initial impact region. 7 to 10 show the shape of a preferred embodiment of the additional deformation regions 20.

11 to 13 show the shape of a preferred embodiment of the side rail mounting portions 14. The shape and configuration of the side rail mounting portions 14 are affected in large part by the layout of the vehicle to which the bumper 10 is to be attached, such as the shape of the fascia and the position of the side rails. In addition, the side rail mounting portions 14 have inherent performance requirements, for example a collision angle of 30 degrees, and moreover their shape will be influenced by the requirements for meeting these requirements.

In the initial impact region 18 (see FIG. 6), the top surface 30 is labeled '30a' and the bottom surface 32 is labeled '32a'. In the additional deformation regions 20 (see FIGS. 7-10), the top surface 30 is labeled '30b' and the bottom surface 32 is labeled '32b'. The side rail mounting portions 14 (see FIGS. 11 to 13) of the bumper 10 have a top surface 30c and a bottom surface 32c, respectively.

In the preferred embodiment of the bumper 10, the front surface 41 is long enough to define a cured channel 45 between the upper protrusion 42 and the lower protrusion 44. A top protrusion 42 and a bottom protrusion 44 extending along the cured channel 45 preferably extending along at least the front impact portion 16 of the front surface 41. The cured channel 45 ) Increases the hardness of the front surface 41, thereby preventing undesirable buckling in the event of a collision.

The rear surface 43 includes an upper bent edge 46 connecting the rear surface 43 and the top surface 30 and a lower bent edge 47 connecting the rear surface 43 and the bottom surface 32. It is desirable to. Preferably, the upper and lower bent edges 46, 47 of the rear surface extend along the entire length of the bumper 10. In the initial impact region 18 (see FIG. 6), the upper bent edge 46 is labeled '46a' and the lower bent edge 47 is labeled '47a'. In the additional deformation region 20 (see FIGS. 7-10), the upper bent edge 46 is labeled '46b' and the lower bent edge 47 is labeled '47b'. The side rail mounting portions 14 (see FIGS. 11 to 13) of the bumper 10 include an upper bent edge 46c and a lower bent edge 47c. The side rail mounting portion 14 also includes an indent 49 formed on the rear surface 43. The indent 49 may be used to "absorb" the material reducing the cross-sectional area of the side rail mountings 14 to help meet layout requirements.

Referring to FIG. 6, the top surface 30a and bottom surface 32a of the initial impact region 18 are generally flat. In the frontal collision with an obstacle, the upper surface 30a and the lower surface 32a tend to be convexly buckled, such that the flat upper surface 30a and the lower surface 32a prevent this undesirable buckling in the initial impact area. This improves the performance of the bumper at low speed forward collisions.

7 to 10, the top surface 30b and bottom surface 32b of the additional deformation region 20 are generally convex, as shown in the convex regions 46 and 48. In the additional deformation region 20, it is known that the buckling pattern during anterior collision tends to be concave. Thus, by providing the convex top surface 30b and the bottom surface 32b, concave buckling can be prevented, which also helps to improve the performance of the bumper 10.

Referring to FIG. 3, the top surface 30a of the initial impact region 18 and the top surface 30b of the additional deformation regions 20 each have a single continuous top surface 30 of the front impact portion 16. It includes an area. Equally, the bottom face 32a of the initial impact region 18 and the bottom face 32b of the additional deformation region 20 each comprise an area of a single continuous bottom face 32 of the front impact portion 16. Preferably, the upper and lower surfaces 30 and 32 of the front impact portion 16 taper gently from generally flat in the initial impact region 18 to generally convex in the additional deformation regions 20. taper).

As described above, the moment of inertia of the bumper also affects the performance of the bumper. In a preferred embodiment, the minimum moment of inertia of the initial impact region 18 in relation to the collision direction shown by arrow A (see FIGS. 5 and 6) is also the respective additional deformation region 20 in relation to the collision direction A. Will be greater than the maximum moment of inertia. Preferably, the moment of inertia of the front impact portion 16 with respect to the collision direction has a maximum at a position corresponding to the overall center point 26 of the center of mass path 22 in principle, and generally the side rail mounting portions 14 Has a minimum at the ends located around the points 24j and 24c of the additional deformation regions 20 close to. In a particularly preferred embodiment, the moment of inertia of the front impact portion 16 is generally located around the points 24j and 24c of the additional deformation regions 20 from a maximum at a position corresponding to the center point 26, Decrease continuously to the minimum value at the two ends. The moment of inertia does not need to be reduced completely continuously from the front impact portion 16 to the ends 24j, 24c through the additional deformation regions 20 and is less than the moment of inertia of the portion where the moment of inertia is located more internally. It will be appreciated that there may be parts of the higher bumper. Those skilled in the art will appreciate that a generally continuous reduction of the moment of inertia from the center point 26 to the ends 24j, 24c is applied to the front impact portion 16 and the bumper 10 as a whole. It will be appreciated that this does not apply across. Thus, the side rail mounting portion 14 may include portions having a moment of inertia greater than the moment of inertia at the ends 24j, 24c of the front impact portion 16, and for the front impact portion 16. It may even include a portion having a moment of inertia greater than the maximum moment of inertia. The specific moment of inertia for a given portion of the side rail mounting portion 14 will be affected by performance requirements, such as, for example, a collision angle of 30 degrees, and by the layout requirements of the vehicle to be guaranteed.

[0046] It is desirable to increase the hardness of the initial impact region 18 and thereby prevent buckling. On the other hand, the hardness in the additional deformation region 20 decreases for improved strain distribution along the bumper beam. While a certain amount of hardness is needed in the initial impact region 18, higher stress concentrations can be caused if the additional strain regions 20 become too hard and thereby increase the resistance to bending. This makes the bumper more susceptible to undesirable buckling. For this reason, the bumper 10 is preferably of maximum impact 'A' (see FIGS. 5 and 6), which is maximal in the initial impact region 18 and reduced in the additional deformation regions 20, as described above. It has a moment of inertia with respect to the direction. The moment of inertia at various points on the bumper 10 depends on the precise shape and configuration of the bumper 10. The ideal configuration will be affected by the weight of the vehicle to which the bumper is attached and the stroke (s) and force (F) requirements set by the manufacturer. Those of ordinary skill in the art will appreciate It will be appreciated that any number of configurations may be used to provide the bumper with the moment of inertia characteristics described above without departing from it.

Referring to FIG. 5, which is a top view of the bumper 10, it can be seen that the theoretical center of mass path 22 has a longitudinal longitudinal radius of curvature that is not constant in the direction of the impact 'A'. By way of example only, a distinct change in the radius of curvature can be seen at points 24b and 24k, and more subtle changes can be found in theory along the center of mass path 22. This non-constant radius of curvature may be made by a hydroforming process for the hollow hollow tubular beam 12 of UHSS forming the bumper 10.

6 to 13 again, the upper protrusion 42 of the front surface 41 protrudes outward more than the lower protrusion 44. Referring to FIG. 4, such a configuration is advantageous in that the bumper 10 is aligned with the vehicle's fascia 50, so that when the bumper 10 and the fascia 50 are mounted to the vehicle, the front impact portion ( The outer front surface 41 of 16 will be minimally spaced apart from the inner surface 52 of the fascia 50. In particular, with respect to the vehicle in which the fascia 50 is mounted, where the fascia 50 is inclined downward and inward, the use of the upper protrusion 42 protrudes more than the corresponding lower protrusion 44. Silver bumper 10 more closely fits the shape of inner surface 52 of fascia 50. This will reduce the distance traveled by the fascia 50 when deformed at impact at very low speeds, while reducing the likelihood that the fascia 50 will be damaged from a collision such as a slow collision. For example, when the front of the vehicle is slightly impacted during in-line parking, the fascia 50 will not deform enough to crack or permanently sink before contacting the harder bumper 10. Therefore, there is no need to replace or repair the fascia 50, or to withstand the minute cracking and the resulting depression.

6 to 13, a large number of reference values are indicated. In particular, each number represents three horizontal depths, generally denoted D _A , D _B, and D _C , and three vertical heights, generally denoted H _A , H _B, and H _C. Each depth and height is also identified by its corresponding number, so D _6A is the depth D _A corresponding to FIG. 6, D _7A is the depth D _A corresponding to FIG. 7 and so on. Here, "horizontal" means a direction parallel to the direction of the impact A shown in Figures 5 and 6, "vertical" means a direction orthogonal to the direction of the impact A.

Each height H _6A to H _13A is approximately the point where the top surface 30 starts to bend to become the upper protrusion 42 and the bottom surface 32 starts to bend to become the lower protrusion 44. In between is generally the vertical height of the bumper 10 at the point behind the cured channel 43. Height H _13A passes through the edge of the hardened channel 45. In the additional deformation region 20 (see FIGS. 7-10), each height H _7B- H _10B is the vertical height of the bumper 10 measured between the convex regions “46” and “48”, and the initial impact In the impact section), the height H _6B is generally referred to as a bumper (at a point corresponding to the position of the convex regions “46” and “48” above the top 30b and bottom 32b of the additional deformation region 20). 10) is the vertical height. Also height H _11B to H _13B (See FIGS. 11 to 13) is the vertical height of the bumper 10 at points generally corresponding to the positions of the convex regions “46” and “48” of the additional deformation region 20. Each height H _C is the vertical height of the bumper 10 at points just ahead of the upper bent edge 46 and the lower bent edge 47 of the rear surface 43.

[0051] depth of each D _6A to D _13A Is the horizontal depth measured between the upper protrusion 42 and the rear surface 43. Each depth D _6B to D _10B Is the horizontal depth measured between the cured channel 45 and the back surface 43. Whereas each depth D _11B through D _13B is the horizontal depth measured between the cured channel 45 and the back indent 49 which is part of the back surface 43. Each depth D _6C through D _13C is the horizontal depth measured between the lower protrusion 44 and the back surface 43.

All depths D _A , D _B and D _C , and all heights H _A , H _B and H _C are measured in relation to the outer surface of the bumper. The table below shows the relative figures of a particular embodiment of the bumper 10. Indicates. These values start at the center point 26 and move outward in theory, increasing by 0.1 m along the center of mass path 22. The measurements were taken to the first decimal place in millimeters.

Example Numerical values

Increase in meters from center point 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 number 6 7 8 9 10 11 12 13 H _A (mm) 75.8 74.5 73.2 75.8 82.4 87.1 89.5 90.5 H _B (mm) 75.7 80.1 79.9 78.2 82.7 90.2 91.1 90 H _C (mm) 70.2 70.3 68.6 70.6 78.3 86.2 88.1 88.5 D _A (mm) 99.2 99.7 99.9 98.4 91.9 82.9 76.6 73.7 D _B (mm) 89.5 87.4 86.3 87.2 81.5 67.1 54.3 47 D _C (mm) 93.2 93.7 93.9 92.4 85.9 77.1 71.5 68.1

In the above embodiment, the bumper 10 has a border of approximately 319 mm. Although there may be small variations due to minor deformation of the material during the hydroforming process, this boundary is preferably essentially constant along the length of the bumper 10.

Those skilled in the art of the present invention represent one preferred embodiment by way of example only, and numerous other embodiments having different numerical values are defined by the appended claims. It will be appreciated that it will be included within the scope of the invention.

As described above, the bumper 10 is preferably formed by a hydroforming process. Hydroforming is well known in the art and can be briefly described below without limitation. The hollow tube can, if necessary, be first longitudinally bent to give the approximate shape of the intended final component, while preserving the original circumference while preserving the essentially circular cross section. The hollow tube is then placed on a die, which is divided into two parts, and the two parts of the die merge. Since both ends of the hollow tube are sealed and fluid is injected through one side of the seal, sufficient pressure must be applied inside the hollow tube so that the outer surfaces of the hollow tube are aligned with the inner surface of the die cavity. Can be applied. The pressure can then be released and the fluid injected therein and the two parts of the die separated so that the final part can be removed. For hydroforming processes, reference may be made to the contents described in US Pat. Nos. 4,567,743, RE33,990 and 4,829,803.

[0056] In order to hydroform super rigid steel (UHSS), special steps are required to avoid breakage of the steel tube. Due to the low elongation of UHSS, UHSS tubes tend to break due to the cooling process introduced when trying to deform in the absence of internal pressure. In particular, when the UHSS tube is deformed between two die portions with no or insufficient internal pressure, the tube will have a concave cross-sectional shape on both sides, and will tend to break in a high stressed concave region. As a result, the first unpressurized deformation must be avoided. At the same time, if the pressure is too high, the tube wall will protrude into the open area between the two parts of the die, or it will eject and break in all cases.

14A, 14B and 14C show a preferred process of hydroforming a UHSS tube. In particular, die 100 includes a first half 102a and a second half 102b, each of which is used to deform the UHSS tube 200. The tube 200 must be pressurized before or at the point of contact with the second half 102b, ie before or at the point at which pressure begins to be applied. This is shown in FIG. 14A as the initial pressure P ₁ . The pressure in the tube 200 then slowly increases as the die 100 is closed and the intermediate pressure P ₂ is greater than the initial pressure P ₁ as shown in FIG. 14B. The pressure continues to slowly increase towards the final pressure P ₃ as the die 100 is sealed, and once the die 100 is completely sealed, the pressure in the tube 200 is final pressure as shown in FIG. 14C. (P ₃ ) and the tube 200 will be formed in the intended shape and the forming process will be complete. The final pressure is, of course, greater than the initial and intermediate pressures.

As the die 100 is sealed, the pressure in the tube 200 will increase. This increase in pressure is because the shape of the tube 200 changes as the die 100 is closed. In particular, the internal volume of the tube 200 has a maximum when the tube 200 has a circular cross section, as shown in FIG. 14A, and decreases from this maximum as the tube deforms. If the amount of fluid contained in the tube 200 remains constant, or decreases at a rate less than the rate of decrease in the internal volume of the tube 200, the pressure inside the tube 200 will increase. To create a pressure increase rate which not only adjustment to the intended smooth the final pressure P ₃ to P ₃ via P ₂ from P _1, which can vary adjustable relief the rate of fluid flowing out of the tube 200 It is preferable to use a relief valve. To achieve the intended increase in pressure, the rate of outflow of fluid through the relief valve is reduced as the die 100 is closed. Alternatively, the pressure may be increased at the intended rate by using a relief valve having a fixed outflow rate and varying the rate at which the first half 102a and the second half 102b of the die 100 merge. Can be increased.

By providing a suitable initial pressure P ₁ and gently increasing the pressure to the final pressure P ₃ as the die 100 is sealed, the tube 200 causes the die 100 to extend outside of the tube 200. As it is sealed, it will be manufactured while flowing directly into die 100 shape. The final pressure P ₃ will be reached at the moment the die 100 is closed, and it will be appreciated that once the die 100 is sealed there is no further pressure increase required to complete the deformation process. Ideally, however, the pressure in the tube 200 may be further increased even after the die 100 is closed, for example to provide internal support to the mounting member. Such holes are typically drilled using perforators (not shown) mounted on die 100 and unrolled into the die cavity, so that tube 200 is completed after forming and still pressurized. Keep it.

Appropriate initial pressure P ₁ The final pressure P ₃ and the rate of increase in pressure depend on the size of the tube being formed and the thickness of the material used. In a particular embodiment described herein, for example, a 100 mm diameter UHSS tube 200 having a thickness of 1.0 to 2.0 mm, the initial pressure P ₁ in the tube 200 is approximately 1000 to 2000 psi, and the final The pressure P ₃ should be about 5000 to 6000 psi. One of ordinary skill in the art will appreciate that when the tube 200 has a thickness close to 1.0 mm, the initial pressure P ₁ should be closer to 1000 psi and the final pressure P ₃ should be closer to 5000 psi. Will recognize. Equally, when the tube 200 has a thickness close to 2.0 mm, it will be appreciated that the initial input P ₁ should be closer to 2000 psi and the final pressure P ₃ should be closer to 6000 psi. Referring to the particular embodiment described herein, the die first half 102a and the second half 102b are approximately 53 mm apart from the initial point of contact with the tube 200, as shown in FIG. 14A. And, in approximately one to two seconds, moves to a fully closed position, as shown in FIG. 14C.

Pressure in the tube 200 causes a stress, known as hoop stress, applied to the tube 200. In the previous method, the hoop stress must always be below the yield limit of the hydroformed UHSS. The purpose is to bend the material of the tube, not to stretch it.

Preferably, when forming the bumper 10, the mandrel method via a rotary draw bender may be used to pre-bend the tube to any required degree. Alternatively, a roll bender may be used. However, this method can reduce the circumference of the tube, requiring design tolerances to create a reduced circumference.

There may be many other variations for achieving the above-described embodiments and processes without departing from the scope of the invention, and all such modifications will be appreciated that they are intended to be embraced within the scope of the appended claims. .

1 is a front perspective view of a bumper according to an embodiment of the present invention;

2 is a rear perspective view of the bumper according to the embodiment of the present invention;

3 is a front view of the bumper according to the embodiment of the present invention;

4 is a cross-sectional view taken at the center point of the bumper according to the embodiment of the present invention and a cross section of the vehicle fascia aligned thereto;

5 is a plan view of a bumper according to a sealing example of the present invention;

6 is a cross-sectional view of the bumper according to the embodiment of the present invention taken along line 6-6 of FIG.

7 is a cross-sectional view of the bumper according to the embodiment of the present invention taken along line 7-7 of FIG.

 8 is a cross-sectional view of a bumper according to an embodiment of the present invention taken along line 8-8 of FIG.

9 is a cross-sectional view of the bumper according to the embodiment of the present invention taken along line 9-9 of FIG.

10 is a cross-sectional view of the bumper according to the embodiment of the present invention taken along line 10-10 of FIG. 5;

11 is an end shaving of a bumper according to an embodiment of the present invention taken along line 11-11 of FIG.

12 is a cross-sectional view of a bumper according to an embodiment of the present invention taken along line 12-12 of FIG. 5;

13 is a cross-sectional view showing the end of the bumper according to the embodiment of the present invention;

14A is a cross sectional view of a hydroforming die in an open position with an annular UHSS tube pressurized therein;

FIG. 14B is a cross sectional view of the hydroforming die in a partially closed position with a UHSS tube pressurized and partially deformed therein; FIG.

14C is a cross sectional view of the hydroforming die in a fully closed position with a UHSS tube pressurized therein and fully deformed.

Claims (14)

In the vehicle bumper, The bumper includes two side rail mounting parts and a front impact part positioned between the side rail mounting parts and continuously formed with the side rail mounting parts. The front impact portion comprises an initial impact region and two additional deformation regions, The initial impact region has an upper surface and a bottom surface positioned between the additional deformation regions, the upper and lower surfaces of the initial impact region are generally flat, And wherein each of said additional deformation regions has a top surface and a bottom surface, and said top and bottom surfaces of said additional deformation regions are generally convex. The method of claim 1, The upper surface of the initial impact region and the upper surface of the additional deformation regions each include regions of a single continuous upper surface of the front impact portion, The bottom of the initial impact region and the bottom of the additional deformation regions each comprise regions of a single continuous bottom of the front impact portion, And wherein the top and bottom surfaces of the front impact portion taper gently from generally flat in the initial impact region to generally convex in the additional deformation regions. The method of claim 2, The bumper comprises a front surface, And the front surface comprises a cured channel extending along at least the front surface of the front impact portion. The method of claim 3, The bumper has a direction of impact, The initial impact area has a minimum moment of inertia relative to the direction of the impact, Each of the additional deformation regions has a maximum moment of inertia relative to the direction of the impact, And wherein said minimum moment of inertia of said initial impact region is greater than said maximum moment of inertia of said additional deformation region. The method of claim 3, The bumper has a direction of impact, The tubular beam has a theoretical center of mass path through the tubular beam, The theoretical center of mass path is symmetrical and has a center point, The front impact portion has a maximum at a point corresponding to the center point and has an inertia moment relative to the direction of impact having a minimum at the ends of the additional deformation regions proximate the side rail mountings, Wherein the moment of inertia of the front impact portion generally decreases continuously from the point corresponding to the center point to the two ends of the additional deformation regions. The method of claim 5, And the beam comprises a super rigid steel. The method of claim 6, The bumper is a vehicle bumper having a non-uniform cross-sectional area, characterized in that formed through a hydroforming process. The method of claim 6, And wherein said beam has an outer surface having essentially constant boundaries. The method of claim 1, The bumper has a direction of impact, The tubular beam has a theoretical center of mass path through the tubular beam, And said theoretical center of mass path has a non-uniform radius of curvature in said impact direction. In the vehicle bumper, The bumper includes a tubular beam that is bilaterally symmetric in the longitudinal direction, has a first and a second end and is hollow in the longitudinal direction, The tubular beam comprises a top surface and a bottom surface, The upper and lower surfaces include generally flat regions located at the center of the bumper with respect to the first and second ends, respectively, The top and bottom surfaces each have a non-uniform cross-sectional area comprising a first convex region located between the first end and the center portion and a second convex region located between the second end and the center portion. Car bumper with. The method of claim 10, The bumper comprises a front surface, And wherein the front surface comprises a cured channel extending along at least the front surface at a position corresponding to the generally flat area and the first and second convex areas. The method of claim 10, The first and second convex regions on the top surface gently taper to the generally flat area on the top surface, And wherein the first and second convex regions on the bottom face are tapered gently into the generally flat regions on the bottom face. In the vehicle bumper, The bumper includes a tubular beam having a hollow interior in a longitudinal direction, which is positioned between two side rail mounting portions and the side rail mounting portions, and is formed in a longitudinal direction continuously formed with the side rail mounting portions. The bumper has a direction of impact, The tubular beam has a theoretical center of mass path, The theoretical center of mass path is symmetrical and has a center point, The front impact portion has a maximum moment at a point corresponding to the center point and a moment of inertia in relation to the direction of the impact having a minimum at the ends of the additional deformation regions proximate the side rail mounting portions, And wherein said moment of inertia of said front impact portion decreases continuously from a point corresponding to said center point to said two ends of said additional deformation regions. The method of claim 13, The bumper has a front surface, And wherein the front surface comprises a cured channel extending along at least the front surface at a point corresponding to the front impact portion.

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