欧阳与创编 2024.03.08
Machine 11春15
时间：2024.03.08 创作：欧阳与 June7,201112/7002 文件：Machine11春15
Friction and LubricationⅡ(86-91)《机械工程专业英语
教程》施平主编 电子工业出版社
Unit22Lubrication and Journal of Bearing
The object of lubrication is to reduce friction, wear, and
heating of
machine parts which move relative to each other. A
lubricant is any
substance which, when inserted between the moving
surfaces,
accomplishes these purposes.Most lubricants are liquids
(such as
mineraloil, silicone fluids, and water), but they may be
solid for use
欧阳与创编 2024.03.08
欧阳与创编 2024.03.08
indry bearings, greases for use in rolling element bearing,
or gases
(such as air)for use in gas bearings. The physical and
chemical interaction
between the lubricant and lubricating surfaces must be
understood in
order to provide the machine elements with satisfactory
life.
The understanding of hydrodynamic lubrication began
with the
classical experiments of Tower, in which the existence of
a film was
detected from measurements of pressure with lubricant.
This work was
closely followed by Reynolds’ paper in which he used a
reduced form
of Navier-Stocks equations in associate with the
continuity equation to
generate a second-order differential equation for the
欧阳与创编 2024.03.08
欧阳与创编 2024.03.08
pressure in the
narrow, converging gap between the bearing surfaces.
This pressure
enables a load to be transmitted between the surfaces with
extremely
low friction, since the surfaces are completely separated
by a fluid film.
The understanding of boundary lubrication is normally
attributed to
Hardy and Doubleday, who found the extremely thin films
adhering
to surfaces were often sufficient to assist relative sliding.
They concluded
that under such circumstances the chemical composition
of liquid is
important, and they introduced the term “boundary
lubrication”.
Boundary lubrication is at the opposite end of the
spectrum from
hydrodynamic lubrication.
Five distinct of forms of lubrication may be identified:
欧阳与创编 2024.03.08
中国海洋大学机电工程专业外语之欧阳与创编
