Advanced Materials Research Vol. 837

Abstract: This Finite element method is one of the most advanced calculating methods for approximation of accurate solutions to engineering problems. Optimization of grabs quay cranes is necessary because most port operators use this type of equipment for loading and unloading bulk cargo. Initial research methods applied in this study are based on observations and surveys conducted on Bocşa 16 t - 32 m mobile quay cranes of MinMetal S.A. Constanta port operator. Modeling and analysis for grabs structure optimization was made with FEMAP and NX NASTRAN - version 10.3.1 applications, which use the finite element method and finite element analysis. After calculations and analysis, the following optimizations resulted:-to increase the grabs closing force (in order to minimize the loss of cargo between jaws and to increase digging force) the lower beam weight must be reduced.-to reduce the amount of cargo drained from the grabs jaws at loading, rubber jaws barriers can be fixed or bars can be welded at grabs jaws.- if cargo has high granulation, in order to reduce grabs weight the plate of the jaw can be cropped.-cups supporting tie rods could be replaced by hydraulic cylinders.The greatest tension is located in the cups supportive arms and in the area where cups are attached to arms. Shafts tensions are larger than the grabs metal structure and are located in shafts-arms contact areas, ie support bearings. In these areas, an optimization can be made by installing ball bearings to reduce friction. The largest deformations occur in the middle area of the arms. To increase safety in operation it is necessary to change the material of the four arms supporting cups, given that deformation of 89.7 mm (~ 9 cm) combined with external factors and / or shock loads can lead to permanent deformation or even material breaks. After changing the material, the model showed that the deformations in the middle area of the arms are substantially reduced, at only 4 mm. In the contact area of the upper arms with the two bars of the upper beam, hazardous tensions may be minimized if there are inserted bearings.

Abstract: The study outlines the geometric analysis of motions executed by the Stewart platform and operated in the environment of a simulator for driving learning to be used by disabled people. The analysis was carried out on the basis of results obtained from the resolved kinematic problem for the inversed platform.

Abstract: The paper presents how to find out motion trajectories for individual platforms incorporated into a Stewart platform. The differential equations for motion of actuators are resolved under the assumed initial preconditions. Also are presented graphs for motions of end tips of actuators incorporated into the platform structure. The study makes up one of indispensable stages within the engineering process aimed to design a vehicle simulator for disabled people to help them learning how to drive a car.

Abstract: Producing of mechanisms for automatic tool (ATCM), for machining centers requires higher performance, in terms of: the reduction of effective time for tool, simplification of kinematic chain, the increasing of reliability and operational safety, the reduction of weight of the entire subassembly, the increasing of positioning accuracy in handling tools. The paper presents how these desiderate can be achieved by improving the dynamic behavior. The objectives of the paper focused on the development of a methodology which allows judicious choice of functional-constructive parameter values, still from the design phase in order to achieve an optimization of the dynamic behavior of mechanisms for automatic tool change. The inclusion of dynamic model for the actuation (hydraulic) in full dynamic model has the advantage that it takes into account real parameters which are involved in the operation of these mechanisms. This paper develops a methodology that allows judicious choice of functional-constructive parameter values, still from the design stage. To obtain a version that is the closest to optimal functioning, in terms of dynamic analysis of the mechanism, the authors propose to develop a method of multi-criteria evaluation on dynamic characteristic parameters. This method ensures the choosing the closest to optimal functioning, in terms of dynamic analysis of mechanism.

Abstract: Having in mind the need of the computer adding of the technical production preparation functions the elaboration of models of the design and knowledge representation is essential. In order to prepare these models the object paradigm in the meaning of object oriented techniques and the UML language would be applied. Thanks to this solution the coherent representation of the design and manufacturing knowledge in the framework of a new created CAPP is possible to achieve. The main purpose of the presented work is to show and discuss original models of a design and manufacturing knowledge representations. In the proposed solution the product design is represented by means of the hierarchical class structure in which a particular class is responsible for representing a characteristic type of the model feature. The manufacturing knowledge similarly to knowledge representation is also represented by means of the hierarchical class structure. Each class in the manufacturing knowledge model stores a certain amount of manufacturing knowledge. This model allow representing both procedural and declarative knowledge. The declarative character of the model results from storing of manufacturing process planning rules whilst procedural one from recording of manufacturing instrumentation, cutting parameters etc. selection procedures. Having these models done it is possible to undertake a research on connections between a design and manufacturing knowledge representations.

Abstract: In this paper an influence of simulated thermal cycle on properties and HAZ structure of 10 mm thick S700MC steel plates. The introduction of thermomechanically processed steels with high yield and relatively low carbon equivalent, will significantly reduce the time of welding works by reducing the preheating temperature, or even complete removal of this processing step, furthermore reduction of cross-sectional areas of structural elements, making welded structures with the same capacity will be more slender and lighter. The simulation of thermal cycles was carried out on a specially built test stand equipped with resistive heating source infrared camera VarioCam Head HR with 50 mm lens and a computer with software IRBIS 3 plus. Simulation was prepared for simple and complex thermal cycle. Simulation studies of thermal cycles consisted of resistive heating of samples prepared for the impact test. Single thermal cycles were simulated at temperatures ranging from 400 to 1300 oC, 100 oC and the cycle complex. For each temperature three repeats were carried out. Specimens were tested on impact, strength test and also hardness and metallographical tests. The study showed that there is a possibility to use a purpose built system to simulate simple and complex thermal cycles of S700 MC steel in specific ranges of the cooling time t_8/5. Analysis of the results of the study showed that the welding thermal cycle strongly influences the structural changes and phase in the HAZ zone of S700 MC steel. Areas of HAZ heated to high temperatures above 1000 [°C], show a sudden drop of toughness to unacceptable levels of impact strength (27 [J/cm²]). This sharp decrease in toughness is associated with uncontrolled separation processes of MX phases and dissolution of carbides, niobium and vanadium carbonitrides in austenite during heating. The study also showed that the chemical composition of steel and especially titanium and aluminium content is sufficient to bind in the HAZ free nitrogen and reduce the aging process. The control of the amount of heat introduced into the joint area during welding will reduce the adverse separation processes in the weld and HAZ which will ensure adequate toughness of the connection. Precise knowledge of the phenomena occurring in the HAZ during the thermal cycle can impact the ability to control properties and structure of the welded joint.

Abstract: Methods of identification of the form of objects based on the signature analysis and invariant to affine transformations are considered. It is shown that these methods can be applied to surface quality assurance. Questions of sensitivity of these methods are considered. Dependences of these methods on noise are brought.

Abstract: Process planning is one of the most important links in planning of the manufacturing system functioning, it coordinates and integrates processes planners, designers and economists intentions. The main goal to reach during the process planning phase is to determine the process plan structure it is manufacturing operations and cuts which have to be applied in order to transform given semifinished product into a product with the strict determined design and properties. Simultaneously process planers strive for working out such a process plan which satisfies criteria of the lowest manufacturing cost and labour consumption taking into account current accessibility of manufacturing resources. Process planning is still one of the most difficult, complex and time consuming process planner activities. Traditionally the process plan is designed with so-called manual method. During process planning with this method a process planner is forced to analyse the sequence of manufacturing cuts and operations in the process plan structure and also to analyse alternative processes taking into consideration achieving as low as possible unit manufacturing cost. In this case the process plan quality in principle depends exclusively on process planner knowledge and skills. Taking into account above the methods of process planning functions automation are searched. This goal can be reached by application of computer tools. Computer methods of process planning went through the long evolution process and their development is characterized by the following features: decreasing of process planner participation in the planning of the base structure of process plan, broad application of technological databases, broad application of technological knowledge bases, and possibilities of cooperation with commercial CAD/CAM/CAE systems [1,. In this paper the detailed information on methods of computer aided process planning are given. The variant, semi generative and generative methods are discussed. The main merits and drawbacks for each method are shown.

Abstract: The paper presents the results of virtual analysis of the stability of mining roof supports loaded by the roof rocks. The hydraulic roof support generally accounts for over 50% of the total value of a coal mining and excavating system. Many reports show that in some conditions roof supports behave differently than foreseen. To explain this phenomena the investigations basing on the virtual model were done [1,2]. This phenomena is very dangerous for miners because this behaviour of a mining roof support may cause dangerous accidents in coal mines. In the investigation process some questions have been asked. Firstly what type of a mining support is more liable to this behaviour. Secondly what work conditions are the most dangerous. To analyse this phenomena it was used models of two types of a mining support. One with two props and one with four ones. Results show that that the problem of plunged of roof parts of a support in the coal bed is consider with the construction of the support. The most dangerous is the roof support with two props. The consequences of this results are the recommendations to use rather supports with four props then two.

Abstract: An important aspect raised in the article is the practical application of rules dedicated to Poka-Yoke systems using real industrial automation components that enable detection of defective elements. The article includes also an optimization of the structure of constructed devices for an unambiguous determination of the Poka-Yoke criteria and a minimization of the possibility of random errors made by the employee (or intentionally deceives of sensor systems). Despite clear conditions of the method the authors observed a lack of publications related to the description of the implementation of equipment elaborated in accordance with the presented methodology in industrial applications. This article presents the author's Poka-Yoke system used for a detection of drawpieces made of steel (with welded nuts) which are components of systems of passenger cars.