Optička digitalizacija prostornog modela projiciranjem kodiranog svjetla

This paper analyzes deviations of a model developed by milling and a CAD model modeled according to its technical documentation. Deviations of model surfaces, dimensional deviations (length, width and height) and deviations of geometric tolerances are analyzed. It is indicated that on the scanned object specific measured values do not meet the appointment requirements in the technical documentation. Errors occurred during the manufacturing, because the selected object is relatively complex and contains many features such as holes, slots, cones and bores. It is noted that 3D scanners can be used to maintain the quality in the production because it is possible to control the resulting errors in geometry, but also for the purpose of reverse engineering and self-control of the production process.U radu su analizirana odstupanja modela izrađenog na glodalici i CAD modela modeliranog prema tehničkoj dokumentaciji istog. Analizirala su se odstupanja površina modela, dimenzijska odstupanja (duljine, širine i visine) i odstupanja geometrijskih torelancija. Pokazalo se da na skeniranom objektu određene izmjerene vrijednosti ne zadovoljavaju postavljenje zahtjeve u tehničkoj dokumentaciji. Do pogrešaka je došlo prilikom same izrade jer je odabrani predmet relativno kompleksan, sadrži mnogo značajki kao što su provrti, utori, konusi i rupe. Vidljivo je kako se 3D skeneri mogu koristiti za održavanje kvalitete u proizvodnji jer je moguće kontrolirati nastale pogreške u geometriji, ali isto tako i za reverzno inženjerstvo te samokontrolu proizvodnog procesa

Optimizacija alata zaštitne kadice za proizvodnju i sklapanje

Many tools for metal forming manufacturing are made by copying similar tools with only minimum adaptation regarding the new product. Since such tools are not optimized for manufacture and assembly, it provides a variety of topics for bachelor theses for candidates at the mechanical engineering faculties. In this paper, the optimization of the metal forming tool for protecting wall regarding manufacture and assembly, performed in a bachelor thesis is presented. The optimization is based on approaches known as Design for Assembly and Design for Manufacture. The resulting tool model shows that there is enough space for improvement that can be done and that considered design approaches could be a source for several new interesting bachelor theses.Mnogi alati za oblikovanje metala deformiranjem su rađeni na osnovi sličnih prethodnih alata i uz minimalne izmjene koje zahtjeva novi proizvod. Kako takvi alati nisu optimizirani za proizvodnju i sklapanje, predstavljaju dobar izvor tema za diplomske radove na strojarskim fakultetima. U ovom se radu predstavlja optimizacija alata zaštitne kadice za proizvodnju i sklapanje izvedenu u diplomskom radu. Optimizacija je utemeljena na pristupima poznatim kao "Dizajn za sklapanje" i "Dizajn za proizvodnju". Model izmijenjenog alata pokazuje kako ima dovoljno mjesta za poboljšanja i kako korišteni pristupi mogu biti izvor za brojne zanimljive diplomskih radove

Optička digitalizacija prostornog modela projiciranjem kodiranog svjetla

This paper analyzes deviations of a model developed by milling and a CAD model modeled according to its technical documentation. Deviations of model surfaces, dimensional deviations (length, width and height) and deviations of geometric tolerances are analyzed. It is indicated that on the scanned object specific measured values do not meet the appointment requirements in the technical documentation. Errors occurred during the manufacturing, because the selected object is relatively complex and contains many features such as holes, slots, cones and bores. It is noted that 3D scanners can be used to maintain the quality in the production because it is possible to control the resulting errors in geometry, but also for the purpose of reverse engineering and self-control of the production process.U radu su analizirana odstupanja modela izrađenog na glodalici i CAD modela modeliranog prema tehničkoj dokumentaciji istog. Analizirala su se odstupanja površina modela, dimenzijska odstupanja (duljine, širine i visine) i odstupanja geometrijskih torelancija. Pokazalo se da na skeniranom objektu određene izmjerene vrijednosti ne zadovoljavaju postavljenje zahtjeve u tehničkoj dokumentaciji. Do pogrešaka je došlo prilikom same izrade jer je odabrani predmet relativno kompleksan, sadrži mnogo značajki kao što su provrti, utori, konusi i rupe. Vidljivo je kako se 3D skeneri mogu koristiti za održavanje kvalitete u proizvodnji jer je moguće kontrolirati nastale pogreške u geometriji, ali isto tako i za reverzno inženjerstvo te samokontrolu proizvodnog procesa

Product Function Matrix and its Request Model

A developed model of the first structural shape of the matrix of product function and its requests model have been shown in practice. It relates functions of the product and its requests model, and technical systems that solve them. Functions are described by parameters, determined by physical laws. The technical systems and functions are related among themselves through correlations that fill the field of the matrix. The correlations are determined through winning parameters. Winning parameters are determined from the set of parameters of each function that have the greatest importance and influence on a specific function. The model is implemented into a developed prototype computer system. The first structural shape of the product function matrix and its requests model for the stator of the electrical motor of the intake unit have been generated through the prototype computer system. By implementing the product function matrix and its requests model in the process of product conceptual design, it becomes possible for a designer to examine himself by comparing the possibilities of implementation of new ideas with previously built products

Essential Preventive Automobile Maintenance during a Pandemic

Passenger cars require different types of periodic maintenance. The most common and well-known procedure is the replacement of oil and filters, the so-called basic service. At the time of a pandemic, there is a need for social distance, reduced interaction between people and avoidance of all possible contamination of personal belongings. Oil and filter changes can be planned and optimized in advance but the replacement interval should not be exceeded for a long period of time. Regular replacement is essential to maintain reliability and operation lifetime of vehicles. Due to the unknown duration of the pandemic, the car owner can approach the maintenance procedure in a do it yourself (DIY) manner. Necessary spare parts can be ordered online and received by a delivery service without a human contact. The paper provides an overview of two-form practical implementation of basic maintenance that includes the replacement of lubricants and filters. The first maintenance form requires a skillful certified technician and the second form, as an interim service, can be carried out by an everyday user with a certain level of technical education who will independently and periodically monitor the car condition

Generiranje funkcijske strukture unutar više-strukturnih matričnih oblika

This paper aims at showing the possibility of improving the initial phase of design process using the matrix function multi-structured form of products and their requests. The developed matrix model is a tool which by using a mathematical model interconnects functions and technical systems that solve them. This is one of the main differences with regard to morphological matrix. By mutual linking of matrices the matrix structure is generated in which the whole functional structure of a product is stored. For the sake of uniformity the functions are described by parameters defined from physical laws. In this way the complete knowledge about a product is registered in matrices enabling the generation of the variant and new products. The model is implemented into a prototype computer Web application with the central relational data base. A higher quality, faster and cheaper management of the design process is thus made possible.Cilj ovoga rada je prikazati mogućnost poboljšanja inicijalne faze konstrukcijskog procesa korištenjem više-strukturnog oblika matrice funkcije proizvoda i njihovih zahtjeva. Razvijeni matrični model je alat koji korištenjem matematičkog modela dovodi u međusobne odnose funkcije i tehničke sustave koji ih rješavaju. To je jedna od bitnih razlika u odnosu na morfološku matricu. Međusobnim povezivanjem matrica generira se matrična struktura u kojoj je pohranjena cjelokupna funkcijska struktura proizvoda. Kako bi se postigla jednoznačnost, funkcije su opisane parametrima određenim iz fizikalnih zakona. Ovako je u matricama popisano cjelokupno znanje o proizvodu koje omogućuje generiranje varijantnih i novih proizvoda. Model je implementiran u prototipnu računalnu Web aplikaciju s centralnom relacijskom bazom podataka. Na ovakav način omogućeno je kvalitetnije, brže i jeftinije vođenje konstrukcijskog procesa

Product Function Matrix and its Request Model

A developed model of the first structural shape of the matrix of product function and its requests model have been shown in practice. It relates functions of the product and its requests model, and technical systems that solve them. Functions are described by parameters, determined by physical laws. The technical systems and functions are related among themselves through correlations that fill the field of the matrix. The correlations are determined through winning parameters. Winning parameters are determined from the set of parameters of each function that have the greatest importance and influence on a specific function. The model is implemented into a developed prototype computer system. The first structural shape of the product function matrix and its requests model for the stator of the electrical motor of the intake unit have been generated through the prototype computer system. By implementing the product function matrix and its requests model in the process of product conceptual design, it becomes possible for a designer to examine himself by comparing the possibilities of implementation of new ideas with previously built products

Modified PROMETHEE Approach for Solving Multi-Criteria Location Problems with Complex Criteria Functions

The specific problem that occurs in multi-criteria decision-making (MCDM) processes is ranking a number of alternatives using complex criteria functions (the hierarchical structure of criteria) whose values must consider the impacts of all-important characteristics and parameters of alternatives. The problem becomes more complex by increasing the number of levels of sub-criteria functions (degree of decomposition). This paper proposes an extended procedure based on the mean values conversion of the net outranking flow of sub-criterion functions obtained by modified PROMETHEE methods. The actual value of criterion functions is used only at the last level, and transformed values of the net outranking flow for generating a final rank of alternatives are introduced at other levels. This procedure provides a more objective comparison of the impact of various individual criteria to rank the alternatives and easier making of unique solution, where the impact of decision-maker (DM) experience and subjective estimation is minimised in the selection. Applicability and practicability of the presented procedure for solving the selection problem of a logistics warehouse location are demonstrated in the analysis of a case study example

Battery Powered Grass Trimmer Life Cycle Assessment – Case Study

Batteries as a power source are the basis for all major hand tool manufacturers as vide variety of portable products became battery powered for more convenient usage. Manufacturers disable unapproved battery applications in their products by designing batteries specific for these products. In practice, the life of power tool batteries depends on two parameters: natural aging and the type of use. In a case study of a Battery Powered Grass Trimmer which battery broke after four years, the repair procedure for the package is shown. However, shortly after the repair, the Battery Powered Grass Trimmer suffered a bearing deformation that rendered it unusable. Due to its age and the unavailability of replacing electric engine, the Trimmer was scrapped and a detailed Life Cycle Analysis (LCA) applying SimaPro methodology is provided. Since the product under study is no longer on the market, a properly functioning, refurbished battery with significantly increased capacity is used in a new battery-powered grass trimmer from another manufacturer. The paper\u27s final consideration underscores the need for an international standard that regulates battery compatibility and reduces waste, especially electronic waste

Modelling Grounding Systems Using the Finite Element Method: The Influence of the Computational Domain Size on the Accuracy of the Numerical Calculation

Simulating the static and dynamic behaviour of grounding systems using numerical methods is a well-established procedure. In order to achieve greater model accuracy, a special attention is usually paid to the construction of more complex models. However, in the modelling process, there are certain factors that have a great influence on the model accuracy regardless of its complexity. They can drastically reduce the accuracy of high-quality complex models. The article elaborates on the ratio influence of the soil dimensions and the dimensions of the buried part of the grounding system, i.e. the influence of the edge distance of the hemispherical soil model from the centre of the grounding system (i.e. computational domain size) on the accuracy of the numerical calculation using the finite element method. In this paper, the physical cause of the influence of the computational domain size on the accuracy of the calculation is explained in detail. The paper gives a mathematical model that accurately describes the influence of the edge distance of the hemispherical soil model from the grounding conductors on the accuracy of the numerical calculation. Based on the presented theory, derived expressions and simulation results, guidelines in the implementation of numerical methods in modelling grounding systems are given. Also, the applicability of these guidelines in other applications such as modelling, analysis and interpretation of resistance data using FEM was considered