Continuous variable cross-section car front longitudinal beam and preparation method thereof

The invention provides a car front longitudinal beam structure and a preparation method thereof. The front longitudinal beam is of a hollow type cavity structure which is formed by connecting an inner plate with an outer plate along a longitudinal extension direction, and comprises an energy absorption region located at the front part of the front longitudinal beam, a support region located at the rear part of the front longitudinal beam and a transition region for connecting the energy absorption region with the support region, wherein a plate material in the energy absorption region is thinner than a plate material in the support region, and the plate material in the transition region is continuously and uniformly transitioned from the energy absorption region to the support region. The inner plate and the outer plate are connected through the adoption of a technology of combining laser welding, spot welding and cementation, so that the front longitudinal beam preparation technology is simple; the transition region of the inner and outer plates is continuously and smoothly connected with the relatively thin energy absorption region and the relatively thick support region, so that difference of front and back performances of the front longitudinal beam is realized, light weight and relatively high collision and energy absorption effects are guaranteed; energy absorbing ribs are arranged uniformly on each surface of the inner and outer plates, so that the car front longitudinal beam structure further improves collision energy absorption and is conductive to further improving car safety performance.