Mathematical Model of Flat Surface Machining Inaccuracies due to Elastic Strains of Technological System

2018 ◽  
pp. 1-14 ◽  
Author(s):  
I. I. Kravchenko
Keyword(s):  
Mathematical Model ◽  
Vector Field ◽  
Model Development ◽  
Technological System ◽  
Mutual Arrangement ◽  
Real Surface ◽  
Main Bearing ◽  
Flat Surfaces ◽  
Internal Surfaces ◽  
Elastic Strains

The paper considers the mathematical model development technique to build a vector field of the shape deviations when machining flat surfaces of shell parts on multi-operational machines under conditions of anisotropic rigidity in technological system (TS). The technological system has an anisotropic rigidity, as its elastic strains do not obey the accepted concepts, i.e. the rigidity towards the coordinate axes of the machine is the same, and they occur only towards the external force. The record shows that the diagrams of elastic strains of machine units are substantially different from the circumference. The issues to ensure the specified accuracy require that there should be mathematical models describing kinematic models and physical processes of mechanical machining under conditions of the specific TS. There are such models for external and internal surfaces of rotation [2,3], which are successfully implemented in practice. Flat surfaces (FS) of shell parts (SP) are both assembly and processing datum surfaces. Therefore, on them special stipulations are made regarding deviations of shape and mutual arrangement. The axes of the main bearing holes are coordinated with respect to them. The joints that ensure leak tightness and distributed load on the product part are closed on these surfaces. The paper deals with the analytical construction of the vector field F, which describes with appropriate approximation the real surface obtained as a result of modeling the process of machining flat surfaces (MFS) through face milling under conditions of anisotropic properties.

Technological System Strength Load Influence on the Flat Surface Machining Accuracy in Face Milling

2018 ◽  
pp. 16-29 ◽  
Author(s):  
I. I. Kravchenko ◽  
V. L. Kiselev
Keyword(s):  
Cutting Forces ◽  
Surface Profile ◽  
Face Milling ◽  
Technological System ◽  
Work Piece ◽  
Machining Accuracy ◽  
Real Surface ◽  
Surface Machining ◽  
Flat Surfaces ◽  
Machining Errors

In engineering technology there is always a problem to improve the accuracy of manufacturing parts. When machining, the arising forces cause both tool and work-piece displacements. In this paper we consider the influence of changing cutting forces on the machining errors that arise in face milling of flat surfaces. With this approach to machining, the cutting forces depend on the work-piece width, the cutter diameter, the number of teeth and their geometry, the mutual bracing of the cutter and the work-piece, and the application point of the resultant force. The paper presents the dependences, allowing us to calculate the cutting force in face milling. The proposed model allows us to determine the vector of deviations in the instantaneous (fixed in time) arrangement of the cutter teeth at the specific points of the surface machined, since different cutting forces act on each tooth on the arc of the contact with the surface. It is recommended that the resulting errors arising from the elastic deformation of the technological system should be evaluated by the vector field, which represents deviations of points of the real surface profile from their nominal position, due to action of the variable cutting forces within one turn of the cutter.

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model Part II: Model Development and Validation

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Ibrahim A Abuashe ◽  
Bashir H Arebi ◽  
Essaied M Shuia
Keyword(s):  
Mathematical Model ◽  
Power Output ◽  
Model Development ◽  
Geometrical Parameters ◽  
Balance Equations ◽  
Solar Chimney ◽  
And Performance ◽  
Development And Validation ◽  
The Mathematical Model ◽  
Good Agreement

A mathematical model based on the momentum, continuity and energy balance equations was developed to simulate the behavior of the air flow inside the solar chimney system. The model can estimate the power output and performance of solar chimney systems. The developed mathematical model is validated by the experimental data that were collected from small pilot solar chimney; (experiment was presented in part I). Good agreement was obtained between the experimental results and that from the mathematical model. The model can be used to analyze the solar chimney systems and to determine the effect of geometrical parameters such as chimney height and collector diameter on the power output and the efficiency of the system

Extended validation of a ground-based three-axis spacecraft simulator model

2020 ◽  
pp. 095441002093896
Author(s):  
H Sh Ousaloo ◽  
Gh Sharifi ◽  
B Akbarinia
Keyword(s):  
Mathematical Model ◽  
Attitude Control ◽  
Aerodynamic Drag ◽  
Center Of Mass ◽  
Model Development ◽  
Optimization Method ◽  
Experimental Results ◽  
Spacecraft Dynamics ◽  
Detailed Model ◽  
Mass Properties

The ground-based spacecraft dynamics simulator plays an important role in the implementation and validation of attitude control scenarios before a mission. The development of a comprehensive mathematical model of the platform is one of the indispensable and challenging steps during the control design process. A precise mathematical model should include mass properties, disturbances forces, mathematical models of actuators and uncertainties. This paper presents an approach for synthesizing a set of trajectories scenarios to estimate the platform inertia tensor, center of mass and aerodynamic drag coefficients. Reaction wheel drag torque is also estimated for having better performance. In order to verify the estimation techniques, a dynamics model of the satellite simulator using MATLAB software was developed, and the problem reduces to a parameter estimation problem to match the experimental results obtained from the simulator using a classical Lenevnberg-Marquardt optimization method. The process of parameter identification and mathematical model development has implemented on a three-axis spherical satellite simulator using air bearing, and several experiments are performed to validate the results. For validation of the simulator model, the model and experimental results must be carefully matched. The experimental results demonstrate that step-by-step implementation of this scenario leads to a detailed model of the platform which can be employed to design and develop control algorithms.

The Study of Elastic Strains of Parts from the Grinding Technological System

2013 ◽  
Vol 371 ◽  
pp. 101-105
Author(s):  
Maxim Casian
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Technological System ◽  
Gear Grinding ◽  
Low Stiffness ◽  
Rotational Direction ◽  
Grinding System ◽  
Elastic Strains ◽  
Element Method

In this paper we present the results of numerical simulation of the stiffness of gear grinding system using finite element method (FEM). Since the rigidity of system can be characterized by two aspects, one static and one dynamic. We will concentrate on the low stiffness of components inside the system to find errors that may affect the precision on the horizontal, vertical and rotational direction of technological system elements.

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