Tolerance Based Assembly of Mechanical Joints using Visual Basic
The goal of this project is to performing assembly of mechanical joints based on tolerance. To obtain the proper functioning at the product the tolerance are important role. In this project the assembly of the component based on it tolerance. The required type of fit information gathered through form. This project is to reduce the time taken for assembly process while manual assembly, to improve the best assembly sequence. In this project to do the assembly of machine elements and its dimension with tolerance values are tabulated while reading the component through VB, and database to be created with the available components. Depends upon the user requirement or the application the appropriate components are identified and assembled in the modelling software. A mechanical assembly is a composition of interrelated parts. Assembly data base stores the geometric models of individual parts, the spatial positions and orientations of the parts in the assembly, and the relationships between parts. The manual assembly is a sophisticated tasks which consume time and requires skilled labour and cost. The work employs Visual Basic, SolidWorks and Excel to develop a database management system for standard components. The secondary development of SolidWorks has been performed by Visual Basic and the system is interconnected with SolidWorks. The outcomes were creating a application form to create a tolerance based assembly application which results in increase in speed of part assembly saving time and cost. KeywordSolidWorks, Visual Basic, Graphical User Interface, Ms-Excel database, Fits and Tolerances __________________________________________________________________________________________________
Design of modular fixtures using a 3D-modelling approach
The need for improved productivity and reduced time to market has been increased significantly in manufacturing processes in recent decades. There are many factors that play a role in providing manufacturing processes with more productivity. One is the use of modular fixtures (MFs). MFs have brought many benefits to manufacturing industries including reduced costs and times of production. An MF can be defined as a complete system that consist different elements for effectively and securely holding the workpiece in place for performing various machining operations. Generally an MF is made by assembling a number of fixture elements in a feasible sequence that is properly determined. Traditionally, the most common method of determination of fixture elements and assembly sequences are making use of 2D drawings and physical models. Obviously these are not efficient methods in the world of advanced manufacturing technologies and there is a vital need for developing more efficient methods. A solution to this is developing a CAD-based 3D-modelling and simulation system to determine the types and of feature elements and the sequence of assembly. Such a system can help fixture designers find the proper MF designs by defining the relationships between fixture elements and workpieces. Designing MFs and fixture elements is a very complex and time-consuming task even by making use of CAD software. A methodology has been developed to simplify this task by determining fixture elements and assembly sequences in a 3D-modelling environment. A fixture elements database is established and the fixture elements are divided into different categories depending on geometries and functions. Currently, MF systems can be constructed from standard MF elements. These elements are pre-manufactured components that include base-plates, clamps, and locators; and they can be re-used after disassembly. These can later be used for other workpieces within a specified range of sizes and shapes. In order to use these elements effectively, the CAD environment is exploited with developing a database which contains 3D models of standard MF elements. For most workpieces standard MF elements can be extracted directly from the developed database. However, for some workpieces with non-conventional geometries or shapes customised fixture elements should be designed in a 3D CAD environment. A modelling approach is used to find the appropriate MF design that suits the machining processes in need. To do so many parameters are taken into consideration including the number of workpieces to be machined; type of machining operation; locating method; clamping mechanism; and so on. The methodology developed for MF design has been implemented in a 3D modelling environment by making use of a powerful 3D modelling software, SolidWorks. It makes use of a database which contains 3D models for standard fixture elements. This database is divided into three main categories and each category is divided into different sub-categories depending on the type and function of the MF elements. SolidWorks software provides an excellent 3D environment that can be utilised to model fixture elements and determine assembly processes. This is accomplished by applying mating relationships after considering workpiece setup and fixture elements to achieve the optimum MF assembly design. This paper explains the methodology developed for semi-automated MF design. A case study has been presented to show the validity of the methodology proposed.
l-Phenylalanine dehydrogenase from Brevibacterium sp. for production of l-phenylalanine by reductive amination of phenylpyruvate
SummaryFor production of l-phenylalanine the reductive amination of phenylpyruvate, catalyzed by phenylalanine-dehydrogenase was examined. To reach high levels and a sufficient stability of the inducible intracellular enzyme, growth conditions of Brevibacterium sp. are optimized. For continuous production of l-phenylalanine in an enzyme membrane reactor, the kinetic parameters of the partially purified enzyme are determined.In continuous production a space time yield of 37.4 g l-Phe l-1 d-1 can be reached.By means of the measured kinetic parameters and simultaneous calculation of the mass balances of all reaction components the behaviour of the reactor can be simulated. For certain conditions the multi-enzyme-system shows multiple steady-states.