机械工程专业英语-施平-没翻译课文补充
日本九州大学-我们都不是神的孩子
机械工程专业英语-施平-没翻
译课文补充
4、工程机械概述
As we look around us we
see a world full of
“things”: machines,
devices, tools;
things that we have
designed, built, and
used; things made of
wood, metals, ceramics,
and plastics. We
know from experience that
some things are
better than others; they
last longer,
cost less, are quieter, look
better, or are
easier to use.
正如我们环
;
;
情况.
Ideally, however, every such item has
been
designed according to some set of
“functional requirements” as perceived by
the designers — that is, it has been
designed so as to answer the question,
“Exactly
perform?”
In the world
of engineering, the major
function frequently
is to support some type
of loading due
to weight, inertia, pressure,
etc.
这样的项目已按设计一些“功能要求
what function should it
From the beams in our homes to the wings
of
an airplane, there must be an
appropriate
structures
that will
perform their functions reliably
for a
reasonable cost over a reasonable
lifetime.
melding of materials,
dimensions, and fastenings to produce
一生中其职能可靠。
In practice, engineering mechanics
methods
are used in two quite different ways:
(1) The development of any new device
requires an interactive, iterative
consideration of form, size, materials,
loads, durability, safety, and cost.
(2) When a device fails (unexpectedly) it is
often necessary to carry out a study
to pinpoint the cause of failure and to
identify potential corrective measures. Our
best designs often evolve
through a
successive elimination of weak
points.
1.
cost.
2.
潜在的纠正措施。我们最优秀的设计往往演变的
To many engineers, both of the above
processes can prove to be absolutely
fascinating and enjoyable, not to
mention
(at times) lucrative.
In any “real” problem there is
never
sufficient good, useful information; we
seldom know the actual loads and
operating
conditions with any precision, and
the
analyses are seldom exact. While our
mathematics may be precise, the overall
analysis
is generally only
approximate, and
different skilled people can
obtain
different
solutions. In the study of engineering
mechanics, most of the problems will be
sufficiently “idealized” to permit unique
solutions, but it should be clear that
the “real world” is far less idealized,
and that you usually will have to perform
some idealization in order to obtain a
solution.
在命令必须执行一些理想化获得一个解决方案。
The technical areas we will
consider are
frequently called “statics” and
“strength of materials,” “statics”
referring to the study of forces acting on
stationary devices, and “strength of
materials” referring to the effects of
those
forces on the structure
(deformations, load
limits, etc.).
静”
备作用力学风和“材料力学”指的是这些部队在
结构上的影响。
While a great many devices are not, in
fact,
static, the methods developed here
are perfectly applicable to dynamic
situations if the extra loadings associated
with
the dynamics are taken into
account (we
shall briefly mention how this is
done).
static
开发的方法是完全适用于动态的情况如果
.
Whenever the dynamic
forces are small
relative to the static
loadings, the system
is usually
considered to be
每当动态势力相对较小的静态负荷
被认为是静态的。
In engineering
the
mechanics,
various
we
types
will
of
appreciate
that are inherent in any real
problem:
Primarily, we will be
discussing things
which are in “equilibrium,”
i.e., not
approximations
accelerating. However, if we look closely
enough, everything is accelerating. We
will consider many structural members to be
“weightless” — but they never are.
We will deal with forces that act at a
“point” — but all forces act over an area.
We will consider some parts to be “rigid”
— but all bodies will deform under load.
在一个区域的行为。我们会考虑的某些部分“刚
We will make many assumptions
that clearly
are false. But these assumptions
should always render the problem easier,
more tractable. You will discover that the
goal is to make as many simplifying
assumptions as possible without seriously
degrading the result.
简化假设没有严重退化的结果。
Generally there is no clear method
to
determine how completely, or how precisely,
to treat a problem: If our analysis is
too
simple, we may not get a pertinent answer;
if our analysis is too detailed, we may
not
be able to obtain any answer. It is
usually
preferable to start with a
relatively simple
analysis and then add more
detail as
required to obtain a practical
solution.
一般
法获得任何答案。它通常是最好先从相对简单的
实际的解决办法。
During the past
two decades, there has been
a tremendous
growth in the
availability of
computerized methods for
solving problems that
previously were
beyond solution because
the time required to
solve them
would have been prohibitive.
At the same
time the cost of computer
capability and use
has decreased by orders
of magnitude. We
are experiencing an influx
of “personal
computers” on campus,
in the home, and
in business.
了几个数量级。我们正经历一个“个人电脑”校
26、车床
The general characteristics
of the machine
tools used in cutting
operations are
reviewed in
this
text. The equipment can be classified
in
different categories depending on their
function
and the accessories
involved. The major
categories are described
below.
在
文章进行阐述。依据功能和所包含的配
Lathes Lathes are generally considered to
be the oldest machine tools and were
developed
in the
basic operations carried
out on a lathe are
turning, boring, and
facing.
车床 车床
1750s产生.
The basic components of the most common
lathe( engine lathe ) are the bed,
headstock,
tailstock, and carriage.
One end of the
workpiece is clamped in a chuck
that is
mounted on
the spindle, the spindle rotates in the
headstock. The other end of the workpiece is
supported
by the tailstock. The
headstock contains the
drive gears for the
spindle speeds, and
through
suitable
gearing and the feed rod, drives
the carriage
and cross slide assembly. The
carriage
provides motion parallel to the axis of
rotation, and the cross slide provides
motion normal
to it. A cutting tool,
attached to a tool
post and to the carriage,
removes material
by traveling
along
the bed. The cutting operation is
performed at
a certain desired peripheral
speed
of
the workpiece, feed rate, and depth
of cut
的基本组成部分是
.托架。工件的一端
旋转。工件的另一端是由尾座支撑。床头包含
A further development
is the automatic lathe.
The movements and
controls
are actuated by various
mechanical means,
such as cams and numerical
and computer
control, thus reducing
labor or requiring
less skilled labor.
不太熟练的劳动力。
Turret lathes (developed in the
1850s)carry out multiple cutting
operations,
such as turning, boring,
drilling, thread
cutting, and facing. Various
cutting tools,
usually up to six are
installed on a turret.
The operation is quite
versatile. It
may be operated by hand or
automatically and,
once set up properly, it
does not
require skilled labor. There
are a great
variety of turret lathes available
for
different purposes.
19世纪50
六个炮塔上安装。操作相当灵活。它可能是
手工操作或自
熟练的劳动力。有种类繁多的炮塔车床可用于
不同的目的
Screw machines (the first screw lathe was
developed in the 1770s)are designed for high
production rate machining of screws and
similar parts. All the operations are
performed
automatically with tools
attached to a
special turret. The bar stock is
fed
automatically after each
screw
has been machined to a finished
product. These
machines may be equipped with
single or
multiple spindles to reduce the
cycle time
per piece.
螺
和类似部件的设计的。所有的操作都由连接到
一个特殊的炮塔的工具自动执行。每个螺丝加
Milling
Machines These are among the most
versatile
and useful machine tools because
they
are capable of performing a variety of
cutting
operations. There is a large
selection of
milling
18世纪70年代开发了第一个螺丝车
machines (developed in the
1860s)available
with numerous features.
The basic types
are
type
outlined
milling -and-column
machines
are the most
common and are used for
general-purpose
machining. The spindle, to
which the milling
cutter is
attached, may be horizontal (for slab
milling), or vertical (for face milling).
它们能够执行各种切割操作。有大量的
19世纪60年
Bed-type
milling machines have the table
mounted on a
bed (replacing the knee) and can
move
only in the longitudinal direction.
These
machines are simple and rigidly
constructed
and
are used for high-quantity
production. The
spindles may be horizontal or
vertical and
can be of
duplex or
triplex types (that is, with two
or three
spindles for simultaneous
machining of two or
three surfaces on a part). Other types of
milling machines are also available, such
as the
planer type for
heavy work and machines for
special purposes
机器。
Among accessories for milling
machines, one
of the most widely used is the
universal
dividing head. This is a
fixture that
rotates the workpiece to
specified angles
between
individual
machining steps. Typical uses
are in milling
parts with polygonal surfaces
and in
machining gear
teeth.
转到指定角度。典型的用途是加工铣削有多边形
表面的零件和加工齿轮齿。
Planers and Shapers These machine tools
are generally used for machining large flat
surfaces although other shapes, such as
grooves, can also be machined. In a planer,
the
workpiece travels under the
cross-rail
equipped with cutting
tools, whereas in a
shaper the
tool
travels and the workpiece is stationary
工大平面
和工件是
固定的。
Because of the size of the workpieces
involved, planers are among the largest
machine tools.
Shapers may be
horizontal or vertical and
are also used for
machining notches and
keyways
也用于加工凹槽和键槽。
Broaching Machines These machines push or
pull broaches, either horizontally or
vertically,
to generate various
external or internal
surfaces. They are of
relatively simple
construction and are
actuated hydraulically and have only
linear motion of the broach. Because of the
great variety of
shapes and parts
involved, broaching
machines are manufactured
in a wide range of
designs and
sizes.
拉床
加工各种内部或外部的表面。他们的构
被制造成各式的设计和尺寸。
Drilling Machines These machines are used
for
drilling holes, tapping, counterboring,
reaming, and other general-purpose boring
operations. They are usually vertical, the
most
common one being a drill press.
Drilling
machines are manufactured in a wide
variety
of sizes,
from
simple bench type units to radial
drills and
large production machines with
multiple
spindles.
床制造成种
臂钻床和有多个主轴的大型生产设备。
46课
Computer-aided design
and product
models. Computer-aided design is usually
associated with interactive computer
CADinvolves the
use of computers to create
design drawings
graphics
CAD system
助设计通常
known as a
.
计算机辅助设计(CAD)涉及到电
脑的使用来创建设计图纸和产品模型。计算机辅
是与交互式
计算机图形学(称为CAD系统)。
Computer-aided design systems
are powerful
tools and are used in the
mechanical design
and geometric
modeling of products and components
计算机
辅助设计系统是强大的工具,用于产品的机械设
计和几何建模和组件 In
CADthe drawing
board is replaced by electronic
input and
output devices. When using a CAD
system
the designer can conceptualize the
object to
be designed more easily on the
Graphics
screen and can
consider
alternative designs or modify a
particular
design quickly to meet the
necessary design
requirements or
changes.
在CAD图纸被电子
输入和输出设备。当使用CAD系统中,设计人员
可以概念化设计的对象
更容易在图形屏幕上,可以考虑替代设计或修改
一个特定设计迅速满足必要的设计要求或更
改。 The designer can then subject the
design
to a variety of engineering analyses
and can
identify potential
problems
deflection
surpass what is available
from traditional
methods.
设计师可以设计各种各样的工程分析
和可以识别潜在的问题(如过度负荷或偏转)。这
种分析
such as an excessive load or
. The
speed and accuracy of
such analyses far
的速度和准确度远远超过可以从传统的方法是
什么。 Draft
productivity rises
dramatically. When
something is drawn once
it never has to be
drawn again. 草案生
产率大幅上升。当有了一次,它从来没有再画。
it
can be retrieved from a library ,and can
be
duplicated, stretched, sized, and
changed in
many ways
without having to be
redrawn。Cut and paste
techniques are used as
labor-saving aids.
它可以从库检索,可以复制,拉伸,大小,改变在
许多方面不用粘贴技术用作省力
艾滋病。 CAD makes possible multiview 2D
drawings
reduction and enlargement.
CAD使可能的多
视图2 d图纸,图纸可以复制在不同程度的减少
和扩大。 It
gives the mechanical engineer
the ability to
magnify even the smallest of
and the drawings
can be
reproduced in different levels of
components to ascertain if
assembled
components fit properly.
它让机械工程师的
能力放大甚至最小的组件来确定如果组装组件
配合得当。 Parts
with different
characteristics
stationary
such as movable or
can be assigned
different
colors on the display.
部分具有不同特点,
如移动或静止不动的,可以指定不同的颜色显
示。 Designers
have even more freedom with
the advent of 3-D
parts and manipulate them
in endless
variations to achieve the desired
results.
设计师有更多自由随着3 d部分和操
纵他们无穷无尽的变化来获得期望的结果。
Through finite element analysis
results
graphically displayed
a design before
the creation of a physical prototype.
通过
giving the designer
quick feedback on
any inherent problems in
stresses
can be
applied to be a computer model and the
有限元分析,压力可以被应用到一个计算机模型,
结果以图形方式显示出来,给设计师提
供快速反馈任何固有的问题在设计物理原型的
创建。 In addition
to the design’s geometric
and
materialsspecification and
manufacturing
instructions
information ,the designer can
then analyze
the economics of alternative
designs. 除了
设计的几何和空间特性,其他信息(如材料的清
单,规范,和生产指令
)存储在CAD数据库。
使用这些信息,设计师可以分析替代的经济设
计。
Computer-aided manufacturing(CAM)
involves the
uses of computers and computer
technology to
assist
is stored in
dimensional
featuresother
information such as a list of
the CAD database. Using such
in all the phases of manufacturing a
product
including process and production
planning
scheduling
control.
manufacturing are often combined into
CADCAM systems. 计算机辅助制造(CAM)涉及
计算机和计算机技术的使用
,协助生产一个产品
的所有阶段,包括
过程和生产计划、加工、调度、管理和质量控制。
计算机辅助设计和计算机辅助制造通常结
合到CAD CAM系统。 This combination allow
the transfer of information from the design
stage into the stage of of planning for
the manufacture of a productwithout the
need to reenter the data on part geometry
management
Computer-aided
and quality
design and
machining
computer-aided
manually.
这种组合允许转让信息从设计阶段
的阶段,规划产品的生产,而不需要手动重新输
入数据部
分几何。 The database developed during CAD
is stored
by CAM
data and
instructions for operating and
controlling
and automated testing and inspection for
product quality.
在CAD开发的数据库存储;
然后进一步处理,通过凸轮,到所需的数据和指
令操作和控制生产
机械、设备来源,自动化测试和检验产品质量。
In machining
operations
describe the tool path for
an important
feature of CADCAM is its
capability to
production machinery
material-handling equipment
then it is
processed further
into the necessary
various
operations
milling
such as NC turning
and
drilling. 在加工操作中,CAD
CAM的一个重要特性是其能力来描述刀具轨迹的
各种操作,如数控车
削、铣削和钻孔。 The instructions
programs
optimize the tool path .
计算机生成的指令
(程序),他们可以由程序员修改优化刀具轨迹。
The
engineer or technician can then display
and
visually check the tool path for
possible tool
collisions with fixtures or
other
interferences. The tool path can be
modified
at any time
part
shapes to be
machined.
工程师或技术员可以
显示和视觉检查刀具轨迹的可能的工具与设备
碰撞或其他干扰。工具路
to accommodate other
are computer
generatedand
they can be modified by the
programmer to
径随时可以修改,以适应其他部分形状加工。
Some typical
applications of CADCAM are
a
bdesign of
tools and fixtures and EDM
cquality control
and
for instance
dprocess
electodes
inspection
programming for
NC
CNCand
industrial
robots
coordinate-measuring machines programmed
on a CADCAM workstation
planning and
scheduling andeplant layout. 一些
典型的CAD
CAM的应用是:(a)为数控编程,数
控,和工业机器人;(b)设计的工具和夹具
和EDM electodes;(c)质量控制和检查,例如,坐
标测量机CAD
CAM工作站程序;(d)工艺规
划和调度;(e)工厂的布局。 The
emergence of
CADCAM has had a major impact on
manufacturingby standardizing product
development and by reducing
design effort
tryout
reduced costs and
improved productivity.
CAD
CAM的出现已经对生产产生重大影响,通
过标准化产品开发和减少设计工作,调试,和
原型工作;它可能显著降低成本和提高生产力。
The two-engine
Boeing 777 passenger
airplane
paperless design
software developed
enhanced CATIA system
mockups were built
for previous
and no prototypes or
such as were required
. The plane is
constructed directly from the CADCAM
an
for example, was designed
completed by
computer
and prototype workit has made
possible significantly
models. 双引擎的波音777客机,例如,设计完
成的计算机(无纸化设计)。飞机构
造直接从开发
的CAD
CAM软件(一个增强的CATIA系统)和任何原型
和模型建立,如需要以前的模型。
50课 Today, computer numerical control
machine tools are widely used in
manufacturing enterprises.
Computer
numerical control is the automated
control of
machine tools by a computer and
computer
program.
今天,计算机数控机床广泛应用于制
造企业。计算机数控机床的自动控制是计算机和
计算机
程序。 The CNC machines still perform
essentially the same functions as manually
operated machine toolsbut
movements of the machine tool are controlled
electronically rather than by hand. CNC
machine tools can
produce the same
parts over and over again
with very little
variation. They can run day
and night
after weekwithout getting tired. These
are obvious advantages over manually
operated machine tools
which need a
great deal of human interaction
in order to do
anything.
数控机器仍执行相
同的函数作为手动机床,但机床控制电子的运动,
而不是用手。数控机床可
以产生相同的部分,一次又一次变化很少。他们
可以日夜不停地运转,一周又一周,没有累了。
这些明显的优势在手动机床,需要大量的人工交
week
互为了做任何事。 A CNC machine tool
differs
from a manually operated machine tool
only
in respect to the specialized
components that make up the CNC system. The
CNC system can be further divided into three
subsystemscontroldriveand feedback.
All of these subsystems must work together
to form a complete
CNC system.
数控机床不同于一个手动机床只
有在尊重专业的组件构成的数控系统。数控系统
可以进一步
分为三个子系统:控制、驱动,和反馈。所有这些
子系统必须共同努力,形成一个完整的数控系
统。 1. control system 1。控制系统 The
centerpiece of the CNC system is the control.
Technically the control is called the
machine control
unitMCUbut the most common names
or just
plain
used in recent years are
controller
control unit
control. This
is the computer that stores
and reads the
program and tells the other
components what to
do.
数控系统控制的核心。技术控制称为机控制
单元(MCU),但近年来最常用的名字是控制器,控
制单元,或者就是简单的控制。这是计算机存储
和读取程序,告诉其他组件该做什么。 2.
Drive
system. 2。驱动系统。 The drive system is
comprised of screws and motors that will
finally turn the part program into motion.
The first component of typical drive
system
is a high-precision lead screw called a
ball
screw
Fig.50.1.
Eliminating backlash in a ball screw is very
important for two reasons. First
high-
precision positioning
can not be
achieved if the table is free to
move slightly
when it is supposed to be
stationary.
Second
materials can be climb-cut safely
if the
backlash has been eliminated. Climb
cutting
is usually the most
desirable method for machining on a CNC
machine.
螺丝和汽车的传动系统是由部分程序,
最终将变成运动。第一个组件的典型的驱动系统
是一
种高精度丝杠称为滚珠丝杆(Fig.50.1)。消除反
应在滚珠螺杆是非常重要
的两个原因。首先,
不能实现高精度定位如果表是免费的移动略当
它应该是固定的。第二,材料可以安全地同向
如果反弹已经消除。爬上切割通常是最可取的方
法在数控加工机器。 Drive
motors are the
second specialized component in
the drive
system. The turning of the motor
will turn
the ball screw to directly
cause the
machining table to move. Several
types of
electric motors are used on
CNC control systemsand hydraulic motors
are also occasionally used.
驱动电机驱动系
统中的第二专业组件。电动机的转动将滚珠螺杆
直接导致加工表。几种类型
的电机是用在数控控制系统和液压马达也偶尔
使用。 The simplest
type of electric motor
used in CNC positioning
systems is the
stepper motor
called a
stepping motor. A stepper motors
rotates a
fixed number of degrees when it
sometimes
receives an
electrical
pulse and then stops until
another pulse is
received. The stepping
characteristic makes
stepper
motors easy to control.
最简单的类型的电动
机用于数控定位系统是步进电机(有时称为步进
电机)。步进电机旋转固
定数量的度当它收到一个电脉冲,然后停止,直
到接收到一个脉冲。步进特性使步进电机容易
控制。 It is more common to use servomotors
in CNC systems today. Servomotors operated
in a smooth
continuous motion—not
like the discrete
movements of the stepper
motors. This smooth
motion leads to
highly desirable machining characteristics
but they are also difficult to
control.
Specialized hardware
controls and feedback systems are needed to
control and drive these motors. Alternating
current
servomotors are currently the
standard
choice for industrial CNC machine
tools.
这
是今天使用伺服电机在数控系统中更为普遍。伺
服电机运行在一个光滑、连续的活动,如
离散运动的步进电机。这光滑的运动导致高度理
想的加工特点,但他们也难以控制。需要专
门的硬件控制和反馈系统控制和驱动这些汽车。
交流电伺服电机目前工业数控机床的标准选
择。 3. Feedback System 3。反馈系统 The
function of a feedback system is to provide
the control with information about the
status of the motion
AC
control systemwhich is described in
Figure
50.2. 反馈系统的功能是为控制提供运
动控制系统的状态信息,如图50.2所示。 The
control can compare the desired condition to
the actual condition and make corrections.
The most obvious information to be fed back
to the control on a CNC machine
控制可以比
较所需的条件的实际条件和改正。最明显的信息
反馈给控制数控机器上 tool
is the position
of the table and the velocity
of the motors.
Other information may also be
fed back that
is not directly related to
motion control
such as the temperature of the
motor and
the load on the
spindle—this information protects the
machine from damage.
工具的位置表和汽车的
速度。其他信息也可以反馈,不是直接关系到运
动控制,如电动机的温
度和负载spindle-this信息保护机器免受损
坏。 There are two main types of control
systems
have any device to determine
if the
instructions were carried out. For
example
in an open-loop system
the
control could give instructions to turn
the
motor 10 revolutions. However
information can
come
back to the control to tell it if
it actually
turned。All the control knows is
that it
delivered the instructions.
Open-loop control is not used for critical
systems
systems in which accuracy and
reliability
are not critical.
主要有两种类型的控制系统:
but it is a good choice for
inexpensive motion control
no
open-loop and closed-loop. An
open-loop
system does not
开环和闭环。一个开环系统没有任何设备来确定
指令进行。例
如,在一个
开环系统,控制可以给指令将电动机
10革命。然而,任何信息可以回到控制告诉它,
如果它实际上控制知道是它的指示
交付。开环控制不用于关键系统,但这是一个不
错的选择廉价的运动控制系统的精度和可靠性
并不是最关键的。 Closed-loop
feedback uses
external sensors to verify that
certain
conditions have been met. Of
course
position and velocity feedback is
of primary
importance to an accurate CNC
system.
Feedback is the only
way to
ensure that the machine is behaving
the way
the control intended it to behave.
闭环反馈使用外部传感器验证某些条件已经满
足。当然,位置和速度反馈是最重要的一个精
确的数控系统。反馈是唯一的办法,以确保机器
的行为控制计划的行为方式。