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2024年4月17日发(作者：sqlserver找不到配置管理器)
河北工程大学毕业设计
外文翻译：
Fundamentals Of Machine Tools
In many cases products from the primary forming processes must undergo
further refinements in size and surface finish to meet their design specification. To
meet such precise tolerances the removal of small amounts of material is needs.
Usually machine tools are used for such operation.
In the United States material removal is a big business--in excess of $
3610
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per year, including material, labor, overhead, and machine-tool shipments. Since
60 percent of the mechanical and industry engineering and technology graduates
have something connected with the machining industry either through sale, design,
or operation of machine shops, or working in related industry, it is wise for an
engineering student to devote some time in his curriculum to studying material
removal and machine tools.
A machine tool provides the means for cutting tools to shape a workpiece a
required dimensions; the machine supports the tool and the workpiece in a
controlled relationship through the functioning of its basic member, which are as
follows:
(1) Bed, Structure or Frame. This is the main member which provides a basis
for, and a connection between, the spindles and slides; the distortion and vibration
under load must be kept to a minimum.
(2) Slides and Slideways. The translation of a machine element (e.g. the slide)
is normally achieved by straight-line motion under the constraint of accurate
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河北工程大学毕业设计
guiding surfaces (the sildeway).
(3) Spindles and Bearings. Angular displacements take place about an axis of
rotation; the position of this axis must be constant within extremely fine limits in
machine tools, and is ensured by the provision of precision spindles and bearings.
(4) Power Unit. The electric motor is the universally adopted power unit for
machine tools. By suitably positioning individual motors, belt and gear
transmissions are reduced to a minimum.
(5) Transmission Linkage. Linkage is the general term used to denote the
mechanical, hydraulic, pneumatic mechanisms which connect angular and linear
displacements in defined relationship.
There are two broad divisions of machining operations:
(1) Roughing, for which the mental removal rate, and consequently the
cutting force, is high, but the required dimensional accuracy relatively low.
(2) Finishing, for which the metal removel rate, and consequently the cutting
force, is low, but the required dimensional accuracy and surface finish relatively
high.
It follows that static loads and dynamic loads, such as result form an
unbalanced grindingwheel, are more significant in finishing operations than in
roughing operations. The degree of precision achieved in any machining process
will usually be influenced by the magnitude of the deflections, which occur as a
result of the force acting.
Machine tool frames are generally made in cast iron, although some may be
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