- TITLE:
PRINCIPLES OF CREATING A DIAMOND ABRASIVE TOOL TAKING INTO ACCOUNT THE FEATURES OF THE MICROCUTTING PROCESS
- AUTHOR(S):
F. Salenko, L.F. Golovko, Salenko, V.T. Shchetynin, R.H. Arhat, M.R.F. Budar
- ABSTRACT:
The article discusses the creation of a modern diamond-abrasive tool for processing specific
materials - carbon-carbon composites, which have high strength, temperature resistance, and low
machinability. The anisotropy of the material structure, porosity, the tendency to crack formation
with the release of a significant amount of dust makes the processing of such materials with
traditional tools problematic. The application of a functional approach to the design of the working
surfaces of the tool, including the non-rigid one (in the form of diamond threads, saws of the
renovator), is proposed, which allows the cutting surfaces to be considered as a set of separate
clusters, the functional properties of which are focused on ensuring maximum productivity in each
specific zone of material processing. This significantly reduces dust contamination on the surface,
improves and stabilizes the cutting process
- PAGES:
2-
- TITLE:
EFFECT OF DIAMOND BURNISHING PROCESS VELOCITY ON 41Cr4 STEEL SURFACE INTEGRITY
- AUTHOR(S):
V. P. Dunchev
- ABSTRACT:
Diamond burnishing (DB) is a static mechanical surface treatment process based on severe
plastic deformation on the surface layer of the metal work-pieces. The main feature of the DB is that
the tangential contact type between the diamond deforming element and the surface being treated -
sliding friction contact. DB significantly reduces the roughness (up to mirror-finish surfaces),
increases the surface micro-hardness, introduces the beneficial residual stresses and modifies the
microstructure of the surface and subsurface layers in terms of grain refinement. Thus, DB
dramatically improves the surface integrity (SI) of the metal components. The basic governing
factors of the DB are the radius of the spherical-ended diamond, burnishing force, feed rate and
burnishing velocities. This article presents the outcomes from the experimental investigation of the
influence of sliding burnishing velocity on SI of 41Cr4 steel. It was established that the burnishing
velocity influences slightly on the SI. The increased burnishing velocity leads to slightly decrease of
the roughness obtained, slightly increase of the surface micro-hardness and a reduction of the
surface axial residual stresses; in contrast with the residual axial stresses, the residual surface hoop
stresses increase.
- PAGES:
1-
- TITLE:
HEAT TRANSFER ENHANCEMENT BY A COMBINATION OF SPIRALLY CORRUGATED TUBES WITH A TWISTED TAPES PART 2 -THERMODYNAMIC EFFICIENCY
- AUTHOR(S):
V. Petkov
- ABSTRACT:
Extended performance evaluation criteria (PEC) equations for enhanced heat transfer surfaces
have been used to assess the multiplicative effect of combination of spirally corrugated tube with
twisted tape inserts. Thermodynamic optimum can be defined by minimizing the entropy generation
augmentation number compared with the relative increase of heat transfer rate or relative reduction
of heat transfer area.
- PAGES:
61-
- TITLE:
HEAT TRANSFER ENHANCEMENT BY A COMBINATION OF SPIRALLY CORRUGATED TUBES WITH A TWISTED TAPES PART 1 - HYDRAULIC RESISTANCE AND HEAT TRANSFER COEFFICIENTS
- AUTHOR(S):
V. Petkov
- ABSTRACT:
Heat transfer and isothermal friction pressure drop results have been experimentally obtained
for two single-start spirally corrugated tubes combined with five twisted-tape inserts with different
relative pitches in the range of Reynolds number - . The characteristic parameters of the
tubes are height to diameter ratio, e/Di=0.0371 and 0.0261; pitch to height ratio, p/e=11.6 and 15.9;
and relative pitch, H/Di= 15.68-5.80. Significantly, higher friction factor and inside heat-transfer
coefficients than those of the smooth tube under the same operating conditions have been observed.4
10 410
- PAGES:
56-
- TITLE:
A STUDY ON SIMULATION OF METAL CUTTING PROCESS BASED ON LS-DYNA
- AUTHOR(S):
T. T. Tung, N. Y. Nhi, N. T. Anh
- ABSTRACT:
Metal cutting is one of the most important processes in the manufacturing industries for
fabricating a particular product or a mechanical part. It was very difficult to research the
performance of a cutting process because the complex physical phenomenon of the cutting operation
makes it a challenging task in research. This paper presents numerical simulations of the metal
cutting Smoothed Particle Hydrodynamics (SPH) method. In this paper, the two cutting metal models
were built by using SPH technique. The results obtained using the model assures the exactness of the
proposed method and prove that the SPH method is a practical approach for eliminating metal
cutting problems.
- PAGES:
47-
