No. 2 ( 1996)
Articles
ESTABLISHING OF A CALCULATION METHOD FOR THE WORM FROM THE EXTRUDING MACHINE (PRESS FOR FOOD PASTES)
IORDACHE GHEORGHE*, PASAT GHEORGHE*, BIBIRE LUMINIŢA**
The manufacturing of the extruding machines for food pastes (macaronis and other derivates) is done at present on basis of the practical experience gained in time. There fore there is not a calculation method for the main operational parameters of such equipment (flow, paste pressure, necessary driving power). The suggested method, adopted according to the calculation way for the machines for the extruding of polymeric materials, but after making some necessary corrections and using the characteristics of the food pastes, has led to results very close to the adopted model.
THE CHOICE OF THE OPTIMUM OFFER OF EQUIPMENT FOR CRUSHING SOLID MATERIALS
IORDACHE GHEORGHE*, DĂNILĂ SIMONA**, PASAT GHEORGHE*
On basis of the main parameters of the equipment for crushing solid materials (material size at inlet and outlet, flow, installed power) one can determine, from a group of equipment of the same kind, the one where the flow and installed power range within acceptable limits (operational optimizing). The suggested method, to which arc added the equipment price and the advantage of some facilities provided by the manufactured (spare parts, guarantee period etc.) allow a better orientation when selecting the offers.
COULOMBIAN AND UNCOULOMBIAN DRY FRICTION
OPROESCU GHEORGHE, NĂSTAC SILVIU
The dry friction, researched during several centuries, docs not allow to be known in whole its intimacies, Many of its mechanisms were elaborated, various models have been proposed, even quantic ones, but, without the exclusion of the experimental determination to find out the value of the coefficients to stand at the determination of the value of the friction force in a control situation. The lack of the respective values from the specialty literature and the difficulty of their determination imposes the continuation of the experimental researches. In the essay arc presented a method and the stand for the experimental determination of the friction forces and the conclusion which may be drawn even from a summary analysis of determinates values.
MODELLING OF THE INFLUENCE OF MATERIAL FEEDRATE ON GRAIN SEPARATION IN THRESHING UNITS
MIU PETRE
This paper it is analyzed the influence of material federate on grain separation, both for axial and tangential threshing units. Mathematical model that predicts the influence of material feed rate q, on cumulated percentage of separated grain, is also presented. According to the experimental researches, the cumulated percentage of separated grain has a maximum value, with variation of material federate (Figures 2 and 3). At an axial threshing unit, the influence of material federate on grain separation is bigger in barley threshing than in wheat threshing. The influence of material feed rate on the coefficients. and ß from equations (4) and (5), is shown in figures 4 and 5.
MODELLING OF THRESHING LOSSES OF TANGENTIAL AND AXIAL THRESHING UNITS
MIU PETRE
On of the quality index that characterizes the threshing process is the percentage of unthreshed grain, i.e. threshing losses. This paper presents the effects of concave clearance; peripheral speed of cylinder (rotor) and material federate on threshing losses. The mathematical model that can describe the variation of threshing losses when concave clearance varies is represented by the equation (4); see also the Figures 1 and 2. Threshing losses decrease with peripheral speed of the rotor according to the equation (3); see Figure 3. There is a value of material throughput in order that threshing losses have a minimum; Figures 4 and 5.
SOME RESULTS OF ULTRASOUNDS ACTIVATION PROCESSES RESEARCH
CREŢU-NICA MIHAELA
From the researches presented in this work results a lot of opportunities in ultrasound's application in emulgation, homogenization, sterilization, polyurethane building, dental materials preparation and condensation.
FATIGUE STRENGTH OF BOLTED CONNECTIONS UNDER CONDITIONS OF EXCENTRIC CLAMPING AND EXCENTRIC LOADING
CRISTEA ION, BRABIE GHEORGHE
Many of boiled collections in general applications are eccentrically clamped and held under eccentric loading. Foc straight designs, il is important to estimate their fatigue strength under such conditions. In this study, 5 bolted connections of the same geometry were eccentrically clamped in different positions with the same clamping force for evaluation of their fatigue strengths. In the first place, theoretical formulae for the fatigue limits of the bolted connections were derived from the fatigue limit diagrams of the single bolls, with the reduction in initial clamping force due to clamping in the plastic region taken into account. In the second place, experimental values were obtained and analyzed through comparison with the theoretical values.
CONTRIBUTIONS TO THE OPTIMIZING OF HYDRAULIC SYSTEMS USED FOR THE POSITIONING AT THE NONCIRCULAR MACHINING
ZETU DUMITRU, TIŢA IRINA
This paper presents the optimizing procedures as regards the hydraulic systems used for positioning at the noncircular machining as a result of the applying, as precisely as possible, of mathematical models to such systems. The mathematical model makes possible both the pointing out of the optimizing procedures and the quantitative estimation of the results of each optimizing stage.
A STUDY ABOUT THE ADIABATIC FLOW OF THE GAS IN THE RADIAL DAMPER
CAZACU MIRCEA-DIMITRIE*, TOPLICEANU LILIANA**
This study presents the flow through radial damper, attached at the equipment for air supply this considered the operation adiabatic and the fluid with viscosity. Using numerical method for resolution of the set of equations which characterizes the flow through the damper, we obtain the expressions of speed and pressure at different radius of damper.
THE THEORY OF SOURCE DISTRIBUTION APPLIED TO STUDY OF THE SUPERSONIC UNSTATIONARY MOUVEMENTS AROUND THE INTERSECTING PLANE SURFACES
PINTILIE GHEORGHE
In this paper, is presented a recent development in the application of the harmonic gradient method to various lifting surfaces with or without control surfaces. Owing to present method, the optimal number of boxes can be achieved without loss of computation accuracy, and, yet, it is least affected by the given Mach number and reduced frequency.
DEFORMATION OF NUT IN THREADED CONNECTION
CRISTEA ION
The nut deformation, which is the main cause of loosening under repeated axial loads in a bolt-nut unit, is examined analytically and experimentally. A method is proposed to analyze the radial defonnation of the nut, and the deformation of the various nuts is calculated by this method. The validity of the numerical analyses are confirmed by some experiments. Finally, it is shown that the top lace of the nut contracts in radial direction while its bearing surface expands by the force acting on mating thread ridges under tensile load.
THEORETICAL CONSIDERATION AND EXPERIMENTAL RESULTS CONCERNING CRACK OF SHAFTS
BIBIRE LUMINIŢA*, MARIN MARIUS**, MARIN CORINA***
The crack e-f shafts and other mechanisms is often met, but the causes and unfolding way of the process are rarely entirely cleared up. The paper presents some theoretical appearances which are presented by technical bibliographical (part 1) and the experimental results which were obtained as a result of the test with the shaft of pump 125 P1A on its crack, plan ( part II ).
THEORETICAL CONSIDERATION AND EXPERIMENTAL RESULTS CONCERNING CRACK OF SHAFTS (PART II)
BIBIRE LUMINIŢA, MARIN MARIUS, MARIN CORINA
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A COMPUTERIZED METHOD FOR STRESS ANALYSIS OF WIRE-WOUND HIGH - PRESSURE CONTAINERS, SOME RESULTS AND DISCUTIONS
UNGUREANU VIOREL
With a “C” computer programme based on the optimizations method, a whole process of wire –winding can be simulated and the initial and working stresses in a container can be quantitatively estimated represented. Some results of a computer simulation of a wire - winding process regarding radial and circumferential stresses as a radial position in the high - pressure vessel, under and under maximum pressure, are presented. Also a comparison between results of Tresca and criterion used for winding tensions calculations are discussed.
STUDIES CONCERNING THE GEOMETRICAL DEVIATIONS OF THE PORTAL-GRISNDING MACHINE CHIDES
BRABIE GHEORGHE
The study of the geometrical deviations in the case of guiding surfaces offers some useful information concerning their wear and deformation. Also, on the basis of their determinations can be established some indications for the conception and the service stages of the guiding surfaces The paper presents the results of the study concerning the variation and the values of the rectilinear deviations of the guiding elements in the case of portal-grinding machines.
SOME ASPECTS CONCERNING THE DETERMINATION OF THE MAIN-SPINDLE THERMAL DEFORMATIONS
BRABIE GHEORGHE
The paper present and analytical and graphical method which can be use-to the determination of the thermal deformation in the case of the machine-tool main-spindles. Tue knowledge of these deformations permits to the methods and technical solutions for their compensation.
GRAPHICS OF THE BODIES INTERSECTIONS AND THE OPTIMIZATION OF THE DEVELOPMENTS PLOTTING TECHNOLOGICAL PROCESS
CIOBANASU GEORGETA, RACOCEA CRISTINA, SEGAL LIVIU
The paper deals with the approach of the Computer-aided geometric modeling for the determination of the curve intersections of the solid bodies. The construction method characteristic to the solid model are almost intuitively based on logical and technologies operations which are easy to understand. The paper also discusses the problem of generating the developments of some bodies by using AutoLISP programs which are working under AutoCAD.
A CLASS OF SURFACE PATCH IN THE DOMAIN OF FREE-FORM SURFACE MODELLING
RACOCEA CRISTINA, CIOBANASU GEORGETA, SEGAL LIVIU
In the domain of free-from surface modeling, cyclides have attractive properties such a low algebric degree, rational parametric forms and an easily comprehensible geometric representation using intuitive geometric parameters. The paper propose some application of Dupin Cyclide in geometric modeling, the ciclides appear marginally insufficient with respect to degrees of freedom for shape control.
MODELLING IN LABORATORY CONDITIONS OF THE TRIBOCORROSIVE PROCESSES SPECIFIC TO THE TRIBOSYSTEMS FROM THE STRUCTURE OF THE AGRICULTURE AND FOOD INDUSTRY MACHINES AND EQUIPMENTS
TENU IOAN, COZMA DANUT, MUSCA GAVRIL
For the reproduction in laboratory conditions of the tribocorrosive processes which happen at the contact area of the friction couplings from the structure of the agriculture and food industry machines and equipments, was designed and performed a specialized laboratory. Thus, they are created the conditions for the tribocorrosive processes study, depending on the material nature from which the friction couplings are made and on the chemical composition of the aggressive media. Depending on the obtained results, it can be optimized, for certain aggressive technological media, the materials from which the tribosystem semicouplings are made.
AUTOMATICALLY CONDUCT SYSTEM
NĂSTAC SILVIU, OPROESCU GHEORGHE
Automatically systems are useful in many applications. In latest times the engineers studies the possibilities about automatization the raising and transport machines. This issue present an automatically conduct system for autonomous tubs. The basics of this scheme is a guiding system through carrier current. The experiments done with a tub model for raising and transport conteinering wares.
THE COMMAND OF THE SRM AT VARIABLE LOAD TORQUE
LUCANU MIHAI*, ROTAR DAN**
This paper describes a new control method for the switched reluctance motor (SRM) at variable load torque. This control is performed in real time. The control characteristics of the SR motors are analyzed and the control variables arc identified. The main aim of the work described in me paper is the design of a high-performance ripple-free dynamic torque controller for a SR motor. A cascade controller structure is considered.
TIME CONSTANT, SENSITIVITY AND PERFORMANCE OF FEED KINEMATIC LINKAGE OF NUMERICAL CONTROL MACHINE TOOLS
ZETU DUMITRU, STAN GHEORGHE
DETERMINATION OF THE AMPLIFYING CHARACTERISTICS OF AN AMPLIFIER REQUIRED FOR ANALYSIS OF THE NATURAL AND SEMI-NATURAL THERMOCURRENT GENERATED IN TURNING WITH MECHANICALLY FIXED TIPS
DITU VALENTIN
The paper presents a DC amplifier destined for analysis of the natural and seminatural thermocurrent generated in turning with mechanically fixed carbide tips. Well as the accurate determination of the amplifying factor,
PROCESSING POSSIBILITIES OF THE DATA REQUIRED BY AMPLIFYING SYSTEM OF THE THERMOCURRENT OBTAINED IN TURNING WITH MECHANICALLY FIXED
DITU VALENTIN
The paper presents practical processing techniques of the input data required for establishing the amplifying factor of an amplifying system of small/value electric currents, which are generated in turning with mechanically fixed tips and are Input elements for data acquisition plates.
THEORETICAL CONSIDERATIONS ON PAPERMACHIE CLOTHING EFFECTS ON SHEET SURFACE CHARACTERISTICS
FLORESCU DANIELA, FLORESCU IULIAN
It is known that the paper’s quality is depending on rollers surfaces. The erosion of the rollers'oufer covering represents an important problem for paper industry. The paper present a study on papermachine clothing effects on sheet surface characteristics.
THEORETICAL AND PRACTICAL PROCEEDING CONCERNING, PITCH AND STICKIES CONTROL IN PULP AND PAPER MILLS
FLORESCU IULIAN, FLORESCU DANIELA
The sources of some trouble organic contaminants in pulp and paper mills me briefly discussed, including both the naturally occurring wood extractives and the synthetic or man-made contraries which fire introduced with recycled paper products. The study presents different proceeding of determination and control to identify the problem-causing deposits are described.
CONSTRUCTION OF HOT ISOSTATIC PRESSING MAPS FOR ALUMINIUM POWDERS
GEAMĂN VIRGIL, CRISTEA ION
The introduction of sophisticated and highly controlled processing techniques, i.e. single crystal and directional and squeeze casting etc. has provided a mean by which high integrity parts can be manufactured directly from or powders. One way for obtaining pieces with high mechanical and technological properties is the hot isostatic processing. The effect of particle size distribution, internal pressure in the pores and others factors are included.
CONSIDERATIONS UPON SOME PARAMETERS OF TECHNOLOGICAL OPTIMATION IN THE PLASTICAL DEFORMATIONS PROCESS AT THE DRAWING OF WIRES IN ULTRASONIC FIELD
SUSAN MIHAI, ALEXANDRU IOAN, BULANCEA VASILE, RUSU IOAN, BADARAU GHEORGHE
The paper shows the importance that must be given to the drawing speed (vtr) and oscillation speed of the drawing die (vv), as parameters of technological optimation at the wires drawing in ultrasonic field with the u1traacoustic systems dimensioned in n./2, having the drawing die placed in the waves maximum of oscillation and parallel operated wiLh the drawing direction, because "the surface effect of ultrasonic" obtained on the basis of "the friction reversal mechanism" takes place only in the condition vtr/vv<l.
THE GENERALISATION OF THE OPTIMUM HEATING TECHNOLOGIES OF COLD STEEL INGOTS. THE DETERMINATION OF THE RECCURENCY COEFFICIENTS OF THE GRAPHICAL APPROXIMATION CURVES
CATARSCHI V., DIMA ADRIAN, BADARAU GHEORGHE, DRAGAN T. AL.
The elaboration of a new standard for steel ingots heating in furnaces with mobile fireplace, requires first of all the designing of optimal technologies, and then the generalization of these technologies a number of steel mark groups and respectively of typo-dimensions of ingots. This work determines a mathematical non-linear model whose graphical representation gives the best approximation for the heating curves determined by a numeric string with the help of the Spline cubic. The approximation degree between the mathematical non- linear model and the heating curves is being determined with the help of some recurrence coefficients. If the error between the extreme values of these coefficients is less then 5%, then the steel mark and respectively the analyzed typo-dimension of the ingot, makes part from a standard group for which the heating technology is generalized. The methodology of a new standard creation, from which it is presented just one group, is presented in two inter-conditioning works.
THE GENERALIZATION OF THE OPTIMUM HEATING TECHNOLOGIES OF COLD STEEL INGOTS. THE DETERMINATION OF GRAPHIC CONTINUITY FUNCTIONS
CATARSCHI V., DIMA ADRIAN, BADARAU GHEORGHE, DRAGAN T. AL.
The scientific research of the heating technologies, computer aided enables the introduction of a big of variable parameters (with time, temperature) that for the beginning complicate the research logy, but which, after complex mathematical modeling, enables the finding of some generalization of the methodology. Because the most complex phenomena, take place in the case of ingots from the cold state, the generalization can be done on steel mark groups and on sizes groups for the respective heating technology. The research methodology enables the finding of a possibility of making a better betting standard.
ON METALS CASTING IN ULTRASONIC FIELD
PEPTANARIU M. *, LOZOVAN M. *, CHIRIAC H. *, NEAGU MARIA *, POPOVICI RADU **, ALEXANDRU A. ***
The work presents our results concerning the elaboration of the Nispan C alloy in ultrasonic field. The ultrasonic utilization resulted in the increase of the hardness of the Nispan C alloy.
THE CRYOGENIC TREATMENTS AND SOME PROPERTIES FOR PARTS MADE OF BEARING STEEL
LOZOVAN M. *, CHIRILĂ CIPRIAN **, COSMA V. M. ***, CHIRIAC H. *, MOHORIANU S. *, POPOVICI RADU ****, ALEXANDRU A. ***
This study refers to the phase composition influence on the coefficient of expansion of parts made of bearing steel. The tact is well know, that the phase that follow the hardening heat treatments: martensite, carbides and residual austenite have different volume coefficients of expansion. It was determined in this way the coefficient of expansion in limits 20°C... 200°C, of parts which were heat treated and then cooled at cryogenic temperatures of: +30°C; -60°C; 90°C; -120°C; -150°C; - 196°C. It was found that, due to the continuing of cooling at this cryogenic temperatures it was obtained a complex of properties which influence the functional limits of parts working in severe conditions, having very small plays and in conditions of abrasive wear.
APPLICATION OF THE BARKHAUSEN EFFECTS TO DETERMINE INTERNAL STRESS IN FERROMAGNETIC MATERIALS
GRIMBERG R. *, ANDREESCU A. *, APĂVĂLOAIE D. *, COSMA V. M. **, BRADU ELENA*
In this paper we present how can be used Barkhausen effect to measure the internal stress in ferromagnetic materials.
INDUCTIVE HEATERS FOR EXTRACTING BALL-RACES
ANDREESCU A. *, LEITOIU S. *, BRADU ELENA *, RADU E. *, LOZOVAN M. *, POPOVICI RADU **, ALEXANDRU A. ***
Designing the inductive heaters with industrial applications depends on both the conductive material to be heated and the working frequency. The realization of inductive heaters working at the power line frequency of 50 Hz eliminates the main working parameter connected with the penetration (skin) depth of the electromagnetic field in the material. Under these circumstances, the realization of a magnetic circuit adequate for the concentration and direction of the magnetic flux in the inductive heaters allows to extract efficiently the ball races of the inductors the following eddy current densities were obtained: 6.56xl07 A/m2 for a spacing between the material and the inductor of 2.5 mm. and 5.85xl07 A/m2 for a spacing of 2.5 mm, for 4500 Ampere-turns and excitation frequency of 50 Hz.
STUDIES CONCERNING THE BURNING OPTIMISATION IN CERAMIC BURNERS THAT EQUIPE THE MODERNISATED BLAST PREHEATERS
GRANCEA VIOREL, BADARAU GHEORGHE, VIZUREANU PETRICĂ, CONSTANTIN ALEXANDRU, ISACHI PAVEL
EXPERIMENTAL RESEARCHES ON A PREHEATER WITH A FIX LAYER OF REFRACTORY BALLS
GRANCEA VIOREL, BADARAU GHEORGHE, IONIŢĂ IULIAN, VIZUREANU PETRICĂ, MIHAI ALEXANDRU
THE STRAIN DRAUGHT DETERMINATION ON DEFORMO-SFLINTIG PROCESS
RAVEICA IONEL, MARIN ALEXANDRU
The influence of cold hammering is very important in deformo-splinting process. The effects of residual normal stresses, which exist in plastical zone of deformation modify the mechanical characteristics of metals coat. So is usefull to know the distribution of strain draught.
THE COMPARATIVE ANALYZE OF THE MULTIPLE POINT CONTACT IN SUPERFICIAL COLD HAMMERING COAT
RAVEICA IONEL, MARIN ALEXANDRU
The plastically cold deformations modify all phisico mechanical proprieties in deformed plastically coat. The influence of cold hammering hardness is very important in deformo splinting process. This paper proposes to establish the distribution of microhard- ness of superficial cold hammering coat. The effects of residual normal stresses with either uniform or a linear distribution were accommodated in the data analysis method
THE EQUATIONS FOR THE STUDY OF NONSTATIONARY SUPERSONIC FLOW AROUND THIN BODIES
PINTILIE GHEORGHE
In this article, the author have found that seemingly straightforward application of the tangency condition on the body surface, as formulated in wind coordinates, may lead to an apparent inconsistency. lt is purpose of this note to point out this fact and to explain the reason for its occurrence.