- TITLE:
OPTIMIZE QUALITY INDICATORS OF YARN WORKED ON PSK-225 SPINNING MACHINE
- AUTHOR(S):
S. P. Ilieva
- ABSTRACT:
A preliminary study of the factors of influence upon the physical and mechanical characteristics of yarn produced on spinning machine PSK-225 is made. These are twist distribution along length, the influence of pressure in the spinning chambers, speed of air valve on the strength and variability of the finished yarn. Through the planned experiment is determined the effect of the pressure in the spinning and coupling chamber on the strength of the yarn. The regression equations for studied indicators are worked out.
- TITLE:
SYSTEMATIZATION OF THE APPROACHES TO IMPROVE THE FATIGUE LIFE OT METAL STRUCTURAL COMPONENTS WITH HOLES PART III: COMBINED APPROACH
- AUTHOR(S):
G. V. Duncheva
- ABSTRACT:
In this article a method for processing of holes through plastic deformation is grounded. The method combines the beneficial effect from a generation of residual compressive stresses around the holes with the effect of microstructure modification. On this basis, t he method is called Friction Stir Hole Expansion. In accordance with the thermo-mechanical nature of the process its taxonomy is established. The parameters of the process are defined and its thermal aspects are analyzed.
- TITLE:
SYSTEMATIZATION OF THE APPROACHES TO IMPROVE THE FATIGUE LIFE OT METAL STRUCTURAL COMPONENTS WITH HOLES PART II: MICRO-APPROACH
- AUTHOR(S):
G. V. Duncheva
- ABSTRACT:
In this part of the study the idea for processing through plastic deformation in order to modify the microstructure is grounded as one of the basic approaches to increase the fatigue life of the metal structural components. Up-to-date techniques, the effect of which is expressed in grains refining, have been analyzed. A primary attention is dedicated to the Friction Stir Processing (FSP) technique and the phenomena “sticking friction” which is relevant to this technique. It was concluded that FSP technique has a greatest potential in treatment of holes in order to improve the fatigue life of the metal structural components.
- TITLE:
SYSTEMATIZATION OF THE APPROACHES TO IMPROVE THE FATIGUE LIFE OT METAL STRUCTURAL COMPONENTS WITH HOLES PART I: MACRO-APPROACH
- AUTHOR(S):
G. V. Duncheva
- ABSTRACT:
In this study a new slassification of the basic approaches to increase the fatigue life of the metal structural components with openings is grounded. These approaches are based on the concept of “processing through plastic deformation”. In the first part of the study the macro-approach is theoretically developed. A detailed classification of the methods realizing the macro-approach is made using the morphological method. On the basis of deep analysis of the existings methods two innovative methods for cold hole expansion have been developed.
- TITLE:
MODELING THE ROUGHNESS OBTAINED OF RAIL-END-BOLT HOLES PROCESSED ON VERTICAL MACHINING CENTRE
- AUTHOR(S):
A. P. Anchev, V. T. Kuzmanov, I. M. Amudjev
- ABSTRACT:
This article presents the outcomes from experimental investigation of the roughness obtained of rail-end-bolt holes, processed on vertical machining center from the type RV. Firstly, the opening is formed through cutting by means of a special c ombined tool. Then the hole is subjected to slide diamond burnishing through a special device with bilateral action. The study has been conducted through pl anned experiments. Firstly, a mathematical model of the roughness obtained from the first operation (cutting) is obtained. On this basis, the optimal manufacturing parameters – feed rate and speed - are obtained. These parameters ensure minimum initial roughness before diamond burnishing. After that a mathematical model of the roughness is obtained after diamond burnishing. The governing factors are: diamond spherical tip radius, burnishing force, feed rate and burnishing speed. It is established that the first two factors are crucial for the roughness obtained, while the latter two factors have a negligible effect.
