Velocity Control with SGARC 440 Alloy in the Roll Forming Process

Cold roll-forming of metal sections is a significant field in advancing forming of strip metal, and the forming processes are influenced by many factors. The scientific design of passes is worked out by combining theoretical analysis with finite element analysis, in accordance with the principles of cold roll-forming; thus the desired high-quality bending sections are achieved through a combination of theory and practice. This study mainly addresses the velocity of the rolls for sheets that have angle sides, and the spring-back of SGARC 440 alloy sheets in the roll forming process, where we use DEFORM to simulate the sheet.

Large Section Open-Off Cut Supporting Technology of Fully Mechanized Caving Mining for Carboniferous Extra-Thick Coal Seam

In order to resolve the supporting problems of the open-off cuts with span of 10m in Tashan coal mine No.3~5 coal seams, this study investigated and analyzed the problems in the current open-off cuts supporting and the supporting parameters, and performed laboratory test and analysis to the coal and rock's mechanical properties. The open-off cut wall rock in Tashan mine has the problem of serious deformation and high possibility of sudden falling. After academic analysis and numerical calculation, a new supporting mode is designed for the supporting of large span open-off cuts: unite high strength anchor bar, combined anchor rope, W steel strip, metal mesh and concrete to form a group anchor seal effect, therefore maintain the tunnel wall rock's stability and safety. Engineering test was conducted at the 8105 working face open-off cuts, the anchor rope's anchorage force changes in the range of 140 ~ 160kN, the maximum delaminating value of the roof in anchorage zone is about 7mm, and the maximum roof-to-floor convergence is 38mm. The result shows that the proposed "anchor bar - combined anchor rope - concrete" supporting model improved the overall bearing capacity of the supporting structure, controlled the tunnel wall rock's deformation effectively, and also achieved the desired effect of the supporting design, ensured the safety of the large section open-off cuts.

Continuous Production of Metal Matrix Composites from the Semisolid State

Continuous strip metal matrix composite (MMC) casting of 0.3 mm diameter hard-drawn stainless steel (316L) wire in a quasi-eutectic SnPb (64Sn36Pb) matrix was performed by a two-roll melt drag processing (TRMDping) method, with the wire being dragged through a semisolid puddle with a fibre contact time of approximately 0.2 s. A slag weir placed at the nozzle contained two wire guide holes: one located near the upper roll, and the other located between the rolls. A successful continuous composite strip casting with good fibre alignment was achieved by inserting and embedding the wire into the matrix using the guide hole between the rolls. Degeneration of eutectic/dendrite structures led to the formation of globular structures. The occurrence and formation mechanisms of cracks, de-lamination and voids in the matrix were discussed. TRMDping is economically viable and has significant benefits over other MMC fabrication methods.

Modelling of Shape Memory Alloy Negator Springs for Long-Stroke Constant-Force Actuators

The paper deals with the analytical modelling of a shape memory alloy Negator spring. Negator springs are spiral springs made of strip metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbour. This configuration allows a constant force mechanical response and very long strokes, limited mainly from the total length of the spring. The authors investigate the behaviour of the spring made of a shape memory alloy (SMA). The intrinsic characteristic of SMA is to have two different elastic moduli at different temperatures. This difference can be exploited in order to have a net actuation force for the entire very long stroke, overcoming the two major drawbacks of the SMA actuators, short strokes and output force which varies linearly during the travel.

A 3D Rigid-Plastic FEM Simulation on Radius of Incremental In-Plane Bending of Strip Metal

In-plane bending is an advanced plastic processing technology which controls the uneven compressing plastic deformation of strip metal harmoniously and forces the strip metal to produce in-plane bending and to form an open circle. In-plane bending is divided into incremental and continuous process according to the loading manner. While much attention has been paid to the continuous in-plane bending techniques and achievements have been made at home and abroad, only limited experimental investigation has so for been done on incremental in-plane bending by overseas scholars. In this paper, a 3D finite element simulation based on the rigid-plastic principle is performed for incremental in-plane bending of pure aluminum sheet with width of 25 ~ 27.5 mm, thickness of 1.5 ~ 3 mm. Influences of technical parameters such as punch inclined angle αp, punch indentation s, thickness of strip t0, width of strip w0 and strip pitch p on the strip bending radius Rin are studied. The achievement of this study enriches the uneven deformation theory. It lays a theoretical foundation for generalization and industrialization of incremental in-plane bending and offers a new idea to the research and development of the advanced plastic processing technologies.