Fabrication of a Metal Roller Mold with Nanoimprinted Pattern Using Thermal Nanoimprint Lithography

In this work, fabrication of a metal roller mold with nanoimprinted pattern was demonstrated. To get metal nanopattern on a metal roller mold, thermal nanoimprint lithography (TNIL) and subsequent electroforming process were conducted. A poly(methyl methacrylate) (PMMA) nanopattern was fabricated by TNIL process using a polydimethylsiloxane (PDMS) soft stamp on a bare PMMA film. An optimal experimental condition of TNIL process was investigated for large area, uniform PMMA nanopatterning. As a result, large area PMMA line patterns with 200 nm linewidth were fabricated by large-area TNIL process. Electroforming process on the PMMA nanopatterned film resulted in nickel (Ni) nanopattern with a linewidth of 200 nm from the PMMA line pattern. A large area (360 mm by 730 mm in width and length) Ni stamp for a roller mold was fabricated by laser cutting and tiling process of the multiple electroformed Ni stamps. We successfully fabricated a Ni roller mold with feature size of 200 nm in linewidth by attaching the large area Ni stamp to the surface of a roller body.

Design and Research of the Air-Suction Peanut Precision Dibbler

According to exist technical problems and requirements of the air-suction peanut precision mulching film and punching planter, the new air-suction peanut precision dibbler of the planter’ key working part was researched. It was introduced the composition and working principle of the dibbler. According to functional and technical requirements of the dibbler’ main parts, the structural design and analyze were done. The dibbler mainly consists of roller body, cavitations’ components, transmission system, and the air suction metering device. In the peanut growing typical region, field trial of the dibbler showed that overall performance is relatively stable, each component are operating smoothly, and the operating indicators can better meet the technical requirements.

New Kinematic in Dressing of Grinding Wheels

Grinding is the most important process in manufacturing of many precision components. The grinding wheel topography that is generated through dressing operation can directly influence the grinding forces and material removal mechanism. A new dressing concept is addressed in this investigation in order to reach the optimum chip formation condition. The innovative dressing profile roller, “T Dress”, creates a new structure on the wheel owing to which remarkable reduction in grinding forces occurs. The experiments prove about 40% reduction in grinding forces with no great difference in the ground surface roughness values when dressing with the T Dress. Dressing costs reduction owing to less diamond grits used on the roller body as well as about 25% lower dressing force are other advantages which were achieved with utilizing the T-Dress.

Fatigue Life Prediction of Optimum Hollowness of Hollow Cylindrical Rollers in Pure Rolling Contact

Fatigue life investigations have been made for cylindrical hollow rollers in pure rolling contact. In addition to normal loading, the rollers have been subjected to tangential loading of 1/3rd the normal load value. Sufficient coefficient of friction has been used to ensure no slipping occurs. Two main models were built with different hollowness percentages to investigate the hollowness percentage that gives the longest fatigue life. The first model consists of two cylindrical rollers of same size, while the second model consists of two rollers of different sizes. Two cases have been studied, when both rollers are hollow and when only one roller is hollow. The stress distribution in the roller body and the resulting deformation has been investigated using the finite element package, ABAQUS. Then the Ioannides-Harris (IH) theory was used to predict the fatigue life of the hollow rollers in pure rolling contact. Investigations have been made for five different materials, CVD 52100, Carburized steel, VIMVAR M50, M50NiL and Induction-hardened steel. It has been found that the optimum hollowness percentage with the longest fatigue life ranges between 50% and 70%. Many factors affect the optimum hollowness percentage, like the kind of the material used for the cylindrical roller, whether the rollers in contact are of the same size or different size and whether the hollow roller is in contact with another hollow roller or in contact with solid roller. At the optimum hollowness percentage, the roller can live hundred times the life of solid roller. So, as the endurance limit of the material increases, as the fatigue life of the rollers increases too. It has been found that cylindrical roller in contact with another identical sized roller has shorter fatigue life than the cylindrical roller in contact with a bigger roller. That might be related to increase the flexibility of the system that acts as a spring mass system and to the increase of the contact surface area. In case of identical sized models, the longest fatigue life achieved was two hollow rollers of 50% percentage of hollowness. When only one roller is hollow, the optimum shifts to 70% percentage of hollowness. For the non identical sized rollers, the optimum is around 50% but when one roller only is hollow, the fatigue life is longer. That might be related to optimum flexibility that gives the longest fatigue life. If the flexibility of the system is very high, the fatigue life of the roller is reduced because of the effect of the bending stresses.

Three-Dimensional Contact Boundary Element Method for Roller Bearing

The analysis of the forces and the rigidity of roller bearings is a multi-body contact problem, so it cannot be solved by contact boundary element method (BEM) for two elastic bodies. Based on the three-dimensional elastic contact BEM, according to the character of roller bearing, the new solution given in this paper replaces the roller body with a plate element and traction subelement. Linear elements are used in non-contact areas and a quadratic element is used in the contact area. The load distribution among the roller bodies and the load status in the inner rolling body can be extracted.

Influence of Mechanical Architecture and Coupling Effects on the Vibratory Behavior of Complex Gear Transmissions

This paper describes a dynamic model for gear transmissions acting around a static working point, and taking into account the complete mechanical components. Gearbox casing behavior is introduced by using substructure analysis, and a tangent stiffness matrix is defined for each roller body bearing element. This model is used to compare the pullup and pulldown dynamic behavior of a five speed medium size automobile gearbox where the gear meshing phenomena are assumed to be identical. The eigenmodes of the pullup and pulldown models are compared and frequency responses to meshing excitation are studied. Substantial differences between pullup and pulldown behavior are observed and associated with to the orientation of static load.