Corner Strengthening by Local Thickening and Ausforming Using Planar Compression in Hot Stamping of Ultra-High Strength Steel Parts

Hot-stamped products are widely used for the body-in-white of an automobile as they are lightweight and improve crashworthiness. A hot-stamping process using planar compression was developed to strengthen corners of ultra-high strength parts by local thickening and hardening. In this process, the corners are thickened by compressing the blank in the planar direction with the upper and lower dies while blocking the movement of both edges with stoppers in the latter stage of forming. Thickening of the corners largely heightens the strength of the formed parts. Not only the thickness but also the hardness of the corner was increased by large plastic deformation and die quenching. For a hot hat-shaped part, a 30% increase in thickness and a 530 HV20 hardness around the corners were attained. The bending rigidity and strength of the formed parts thickened by 30% in the corners increased by 25% and 20%, respectively. In addition, the improvements of the part shape accuracy and the sidewall quenchability were obtained.

Three-Dimensional Numerical Modeling of a Coastal Highway Bridge under Stokes Waves

This article investigated the effect of structural flexibility on a coastal highway bridge subjected to Stokes waves through a three-dimensional numerical model. Wave-bridge interaction modeling was performed by an FSI model with the coupling of finite element and finite volume methods. An experimental model validated the FSI numerical analysis. Eventually, the overall results of hydrodynamic and structural analyses are presented and discussed. The results illustrate that the structural flexibility significantly increases the initial shock of the wave force on the flexible bridge. In contrast, the fixed bridge tolerates the least forces in the initial shock of the wave force. Then, by adding a wedge-shaped part to the bridge structure, an attempt was made to reduce the initial shock of the wave force to the structure. The results showed the wedge-shaped part with an angle of 30° reduces the initial shock of wave forces down to 50% for horizontal force and 43% for vertical force on the flexible structure.

Porosity distribution in metal injection molded parts

Metal injection molding technology is commonly used in production of small and very complex parts. Residual porosity is unavoidable characteristic of P/M parts, affecting their final properties. During injection molding phase powder-binder separation can occur, causing green density variation through cross section of the part. This behaviour is particularly pronounced as complexity of the parts increases. As a consequence, zones with different density and residual porosity can be seen after sintering. In this regard, porosity and hardness distribution of the sintered ring-shaped part is analysed and presented in the paper.

Research on Comparison of Simulation and Experiment in Warpage Defects in Roll Forming Process of the Cap-Shaped Part Using a Five-Boundary Condition Forming Angle Distribution Function

Warpage is one of the main defects in multi-pass roll forming. It manifests as the horizontal deviation in the sheet flange part after forming, impacting the final quality of the sheet. In this manuscript, we focus on the cap-shaped part of a small section profile. Considering the lack of previous scientific guidance on the distribution of forming angles—angles that lead to warpage defects and other defects reducing the quality of these products—a five-boundary condition distribution function of forming angle is proposed. We propose a mechanism for warpage defects in roll bending of a cap-shaped part based on this five-boundary condition forming angle distribution function. Furthermore, we examine the effects of forming angle, sheet thickness, and material yield strength on the warpage defects by examining the designed fluctuation of the edge wave, ∆z, and the maximum deviation of the profile curves of the flange edge, z', to test this theory, roll bending experiments are compared to simulation.

The influence of the reinforcement of the chisel-shaped area of the ploughshare on the change in the geometric parameters of radial wear during operation

The formation of radial wear is a decisive factor in the removal of shares from service, i.e. this type of wear refers to the characteristics of the limiting state of the part. It is noted that the dynam-ics of its formation and development in a certain way affects the development of technical processes for the restoration of plowshares. However, the process of wear, in this case, cannot be considered fully studied, therefore the work is devoted to the study of the above issue. Experienced plowshares were used for research: as delivered; with a reinforced chisel-shaped part with elliptical rollers; with a reinforced chisel-shaped part with rollers perpendicular to the field edge; with a reinforced chisel-shaped part, rollers perpendicular to the field cut and surfacing of the buried part for a length of about 100 mm. As a result of experiments, the dependences of the change in the width of radial wear in the function of operating time and changes in the depth of radial wear in the process of plowing were obtained. An explanation of the process of wear during the formation of radial wear is given for all investigated technological options. It was revealed that the change in the geometric pa-rameters of radial wear (width and depth) in the process of origin and development has a single character and is the same for all technological variants of hardening with surfacing reinforcement, while the greatest resistance to the formation of this defect is provided by reinforcement by forming beads perpendicular to the trajectory of soil movement with surfacing the deepening part to a length of 100 mm.

ХАРАКТЕР ИЗМЕНЕНИЯ ГЛУБИНЫ ЛУЧЕВИДНОГО ИЗНОСА ПРИ РАЗЛИЧНЫХ ВАРИАНТАХ АРМИРОВАНИЯ ДОЛОТООБРАЗНОЙ ОБЛАСТИ ЛЕМЕХОВ ПРИ ВСПАШКЕ ТЯЖЕЛЫХ ПОЧВ

During the operation of the plow body, a number of defects are formed on the bit-shaped part of the plowshare, one of which is xiphoid wear. Renewing the life of a given part is often reduced to eliminating such wear in various ways that are not always rational. This occurs due to insufficient knowledge of the dynamics of xiphoid wear, especially little information about plowing heavy soils. (Research purpose) The research purpose is in identifying the nature of changes in the depth of xiphoid wear in various options for reinforcing the chisel-shaped area of ploughshares when plowing heavy soils. (Materials and methods) Authors conducted research using all-metal ploughshares of domestic production in the state of delivery and reinforced according to the schemes of the location of reinforcing rollers. The reinforcement rollers were formed using E42A-UONII-13/45 electrodes designed for welding carbon steels. The thickness in the area of the ploughshare wear was determined using a calibration plate, prisms, and an indicator micrometer with an accuracy of 0.01 millimeters. To ensure the same conditions of the experiment, it was carried out in fields where the soils had the same granulometric composition, which was loam with a physical clay content of 33-38 percent. (Results and discussion) The article reveals dynamics of the development of the xiphoid wear depth depending on the operating time and technological methods of strengthening reinforcement of the chisel-shaped part of the ploughshare. The article describes the technology of strengthening reinforcement that provides the minimum wear depth with the same operating time. (Conclusions) The article presents a method for determining the depth of xiphoid wear. The proposed technology of reinforcement of ploughshares with rollers perpendicular to the field edge, with surfacing of the buried part to a length of 100 millimeters and reinforcement of the heel will increase the resource of the part by 1.3 times.