Rib cracking preventing structure for thin-wall frame type steel casting

The invention discloses a rib cracking preventing structure for a thin-wall frame type steel casting. The rib cracking preventing structure is arranged at the corner of a first side frame side wall and a second side frame side wall which are adjacent on the frame type steel casting and comprises at least one anti-cracking rib plate which is integrally molded through a casting die, the first side frame side wall and the second side frame side wall in a casting manner. The anti-cracking rib plate is in a shape similar to a triangle, wherein the two adjacent straight line edges of the anti-cracking rib plate are connected with the first side frame side wall and the second side frame side wall respectively, and the deformed third edge of the anti-cracking rib plate is formed by connecting and combining a first circular arc section, a second circular arc section and a third circular arc section in sequence. According to the rib cracking preventing structure for the thin-wall frame type steel casting, the contracting stress direction can be changed, contracting stress can be transmitted to the rib cracking preventing structure through the casting, a pull crack part happens to the rib cracking preventing structure, cracks are prevented from happening to a casting body, and the cracking preventing problem of a complex structure with multiple contracting stress directions is effectively solved.