Mill finish

Abstract: Lubricants are necessary to avoid adhesion, galling, and scratching in aluminum stamping processes. In this study, various lubricants, including dry lubes and wet lubes, were evaluated using cup drawing test (CDT) for stamping of Al 5182-O aluminum sheets. The effects of surface texturing, with electro-discharge texturing (EDT) and mill finish (MF), on the friction behavior were also investigated. Furthermore, the methodology to evaluate the performance of lubricants was established based on (a) maximum applicable blank holder force (BHF) and (b) draw-in length in flange or flange perimeter of formed cups. Finite element (FE) simulations were carried out to determine the coefficient of friction (CoF) at tool–workpiece interface during deep drawing under different lubrication conditions. Flow stress data of Al 5182-O material were obtained using viscous pressure bulge (VPB) and tensile tests. In this study, it was confirmed that, in forming Al 5182-O, dry film lubricants have better lubricity than wet lubricants. A better lubrication condition was found with EDT surface texture. [DOI: 10.1115/1.4030750]

Abstract: The invention belongs to the field of production machining of special steel of the metallurgical industry, and relates to a rolling production method capable of reducing hardness of 42CrMo. A 42CrMo casting blank serves as a raw material, and the method sequentially comprises following working procedures of heating, descaling, a rough rolling, cooling after rough rolling, continuous rolling, through water cooling, bar reducing sizing mill finish rolling, cooling bed cooling and finally obtaining a finished product bar; by the adoption of the technology, the site operation is simple, online automatic control is easily achieved, and operation labor intensity of a worker is reduced; through the online controlled rolling controlled cold technology, straightness of the 42CrMo steel grade is greatly improved; the subsequent heat treatment technology (annealing technology) is reduced, production cost is saved, the production period is shortened, and the steel market competitiveness is improved; the hardness value range of the obtained 42CrMo steel ranges from 220 HBW to 260 HBW; a metallographic structure comprises ferrite and pearlite; the banded structure is smaller than or equal to 2 levels; the grain size is larger than or equal to 8 levels; and the mechanical property can meet the national standard and user needs.

Abstract: The invention provides a technological process of an FPP mill finish grinding system, which solves the technical problem in the known grinding technology. The technical points are that a material procedure classification is carried out on materials ground by the FPP mill via a dumping double-deck vibrating sieve; coarse-grain materials on a first layer of sieve return to a raw material belt conveyor as the raw material for the FPP mill to grind; the fine grains on the second layer of sieve and the fine-grain materials separated by a powder concentrator are used as backfill materials of the FPP mill; when the backfill materials are excessive, a part of fine-grain materials is extracted and returned to the raw material belt conveyor as the raw materials; 50% or more of finished products in the final mixed powder below the second layer of sieve are separated by the powder concentrator and then stored in the finished product warehouse; and the fine grains as the backfill materials are sent to the FPP mill and ground. The technological process of grinding-sieving, and powder selecting-grinding is performed in cycles. Finally, a non-balling grinding method is realized.