ASME ME Today
Separation apparatuses for separating sheets of brittle material and methods for separating sheets of brittle material (US 20140130552 A1)
Inventors: Keith Mitchell Hill, Ritesh Satish Lakhkar, Mark Thomas Massaro, Liming Wang, Naiyue Zhou. Filed November 15, 2012 in United States
Methods and apparatuses for separating sheets of brittle material are disclosed. According to one embodiment, a separation apparatus for separating a sheet of brittle material includes a first separation cam positioned adjacent to a sheet conveyance pathway and a second separation cam positioned opposite from and downstream of the first separation cam. The first and second separation cams may be rotated such that the contact faces of the separation cams periodically extend across a centerline of the conveyance pathway. Rotation of the first and second separation cams may be synchronized such that at least the portion of the contact face of the first separation cam and at least the portion of the contact face of the second separation cam periodically extend across the centerline of the conveyance pathway at a separation time and periodically do not extend across the centerline of the conveyance pathway at a non-separation time.
Predictive modeling of multi-track laser hardening of AISI 4140 steel
Published by (Materials Science and Engineering: A)
Authors: Ritesh S. Lakhkar, Yung C. Shin, Matthew John M. Krane. Published May 15, 2008
Laser hardening provides benefits over the conventional hardening processes, including minimum distortion in the parts and the absence of a quenchant. This process is also faster than conventional hardening processes and can be used for selective hardening of specific areas of components. One known problem with laser hardening in steels, however, is back tempering when a large area is hardened by multiple, overlapping passes. This study focused on the development of a numerical model to predict the back tempering in multi-track laser hardening. A tempering model was combined with existing models of thermal behavior and phase change kinetics, which were developed earlier in the authors’ group, to predict three-dimensional hardness profiles after multiple track laser hardening. The combined model was first validated through multi-track laser hardening tests and then used to predict and optimize the laser hardened case depth in multi-track laser hardening of AISI 4140 steel. The predictions and parameters optimized to obtain maximum case depth with the least variation along width of the hardened zone were experimentally verified. Case depths up to 2 mm were obtained with 5 mm overlapping of laser tracks.