CAD Solid Modelling Research Papers (original) (raw)
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Each printing method and the materials used for prototype construction have distinct advantages and drawbacks. A large part of the 3D printer producers indicates high printing accuracy (positioning accuracies from 100 µm up to 1 µm and... more
Each printing method and the materials used for prototype construction have distinct advantages and drawbacks. A large part of the 3D printer producers indicates high printing accuracy (positioning accuracies from 100 µm up to 1 µm and layer thickness from 100 µm tо 5 µm). In the process of layers deposition, the material is softened, melted or irradiated with a certain light source to polymerize. Thus, during the printing process, the volume of the materials is changing causing shrinking or expansion which often leads to the occurrence of precision errors in the prototype as opposed to the digital model. This phenomenon leads to distortions of the printed object known as a curling effect. Certain chemical compounds are added by the producers to multiple materials in order to enhance their mechanical and technological properties. However, this often results in changes of some printing parameters influencing the precision and quality of the manufactured object. The aim of the particular study is to establish the allowances with regard to the accuracy during manufacturing precise objects used in micro technologies as well as the necessary adjustments in dimensions because of the shrinkage and the positioning of the SLA 3D printed parts from photopolymer material.
Onion is densely produced crop in India. The harvesting of onion crop is laborious work and requires huge amount of manpower and time. As a part of harvesting of onion, root and shoot has to be trimmed manually, this is a labour oriented... more
Onion is densely produced crop in India. The harvesting of onion crop is laborious work and requires huge amount of manpower and time. As a part of harvesting of onion, root and shoot has to be trimmed manually, this is a labour oriented process. One of the main reasons of low productivity is low level of mechanization and less technology utilizatio n. Machine for cutting root and shoot is not available in India and imported machines are expensive and an Indian farmer cannot afford such high price. Farmers incur financial loss because of non-availability of manpower. The purpose of the work is to " des ign and develop a prototype of onion root and shoot cutting machine " that can cut the root and shoot of onion once fed into the machine. This mechanization will also reduce unit cost of production through higher productivity. The major objective of this work is to reduce total expenses and dependency on labours and to increase the net revenue at an affordable price.
This paper is focused on integration between laser scanning data, CAD modelling and photogrammetric data collected during the survey of one facade of the monument called “Quattro Canti” in the historic centre of Palermo. The investigation... more
This paper is focused on integration between laser scanning data, CAD modelling and photogrammetric data collected during the survey of one facade of the monument called “Quattro Canti” in the historic centre of Palermo. The investigation has been directed to the production of a 3D photorealistic model of the monument. The “Quattro Canti” monument is formed by four cylindrical facades facing the square where the older streets of Palermo intersect; each facade has a symbolic reference to one of the seasons and is divided in four levels. The facade called “Canto dell’Autunno” has been surveyed both with laser scanning and with photogrammetric techniques. Laser scanning data have been collected in a single scan with a resolution of about 7 mm; stereoscopical photos have been taken with a film camera Rollei 6006; all data have been referred to a topographic reference system. The investigation has been restricted to the third level of the “Canto dell’Autunno” facade. The surface model ha...