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Mechanical Engineering English
Lesson 1 Modern Manufacturing Engineering
A．What Is Manufacturing
Maybe you’ve never thought about it before, but it is all around you. It affects every part of your life. What is it? In this case, “it” is manufacturing. Actually “manufacturing” is not all around you. But manufactured products are. Look around you right now. Name some things you see that were manufactured. Chairs, notebooks, blue jeans, books, floor tile, chalkboards, light bulbs, pencils, eyeglasses—nearly
everything around you was manufactured.
The manufacturing industry is important to our society. It’s essential to our economy. An economy is a system for producing and distributing products and services. Many people work in manufacturing. They help produce products. And they buy products with the money they earn. The more products people buy, the more products are manufactured. And this allows more people to work.
Manufacturing is also important to the economy in another way. A piece of material is worth more after it’s been changed into a useful product. That’s added value. Value is increased by the manufacturing process.
B. Modern Manufacturing
A manufacturing industry needs three basic types of resources: Material resources, Human resources, Capital resources.
The elements of industry are seven key steps for organizing production: Research and Development, Production Tooling, Production Planning and Control, Quality Control, Personnel Management, Manufacturing, Marketing.
R&D is the planning of new products, processes, or materials and the improvement of old skill. R&D is such a large, important part of the industrial world and requires many people with different talents.
Production Tooling is the element of industry concerned with these tools. The PT obtains the tools, machines, and equipment needed to make a product.
The most important parts of Production Planning and Control are routing, scheduling, dispatching, and plan layout. The machinery and equipment must be arranged so that production can take place smoothly, without wasted time and effort.
Quality Control can be defined as those activities which prevent defective articles. In this way management tries to insure that a product will be acceptable to the buyer.
Marketing is the process of getting products from those who make them to those who use them and it helps to deliver the right kinds of goods to us, in the right form and amount, at the time and price.
Lesson 2 Mechanical Engineering Design
?? Mechanical engineering design is a major segment of engineering, it deals with the conception, design, development, refinement, and application of machines and mechanical apparatus of all kinds. For many students, mechanical engineering design is one of their first professional engineering courses. Professional engineering is concerned with obtaining solutions to practical problems, and the engineers are able to devise better solutions to practical problems. The most problems in mechanical engineering design do not have a single right answer. Hence, modern mechanical engineers are able to produce distinctly better solutions to meet today’s needs. The engineer must use the best available scientific understanding together with empirical information, good judgment. When considering a complete machine, the engineer invariably finds that the requirements and constraints of the various components are interrelated. The modern engineer has become increasingly concerned with the broader considerations of safety, ecology, and overall “quality of life.”
Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expanded. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.
New designs generally have “bugs” or unforeseen problems which must be worked out before the superior characteristics of the new design can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.
During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.
Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.
英文文獻翻譯
學 生 姓 名：
學 院：
專業(yè)及班級：
學 號：
指導教師：
2011年 4月 25 日
湖 南 農 業(yè) 大 學
全日制普通本科生畢業(yè)設計
3噸叉車液壓系統(tǒng)設計
3 TON FORKLIFT TRUCK HYDRAULIC SYSTEM DESIGN
學生姓名：
學 號：
年級專業(yè)及班級：
指導老師及職稱：
學 院： 工學院
湖南·長沙
提交日期：2013年5月
湖南農業(yè)大學全日制普通本科生畢業(yè)設計
誠 信 聲 明
本人鄭重聲明：所呈交的本科畢業(yè)設計是本人在指導老師的指導下，進行研究工作所取得的成果，成果不存在知識產權爭議。除文中已經注明引用的內容外，本論文不含任何其他個人或集體已經發(fā)表或撰寫過的作品成果。對本文的研究做出重要貢獻的個人和集體在文中均作了明確的說明并表示了謝意。本人完全意識到本聲明的法律結果由本人承擔。
畢業(yè)設計作者簽名：
年 月 日
目 錄
摘要 .......1
關鍵詞 .......1
1前言 .......2
1.1課題背景 2
1.2叉車發(fā)展概況 4
2 液壓元件 6
2.1液壓閥塊簡介 6
2.2集成塊的設計步驟 8
3.1液壓系統(tǒng)設計概述 9
3.2液壓系統(tǒng)設計 11
3.2.1原理圖 11
3.2.2起升油缸最大工作壓力及流量 12
3.2.3求液壓系統(tǒng)最大壓力 13
3.2.4液壓泵站及液壓泵的規(guī)格及選用 13
3.2.5油泵功率及電機選擇 14
3.2.6選擇換向閥 15
3.2.7管道設計與管件的選擇 19
3.2.8液壓油選取 21
3.2.9濾油器及油箱選取 21
3.2.10壓力損失的計算 22
3.2.11節(jié)流閥的設計 23
4 液壓站結構設計 25
4.1液壓站的結構型式 25
4.2液壓泵的安裝方式 25
4.3液壓油箱的設計 27
4.3.1液壓油箱有效容積的確定 27
4.3.2液壓油箱的結構設計 27
4.4液壓泵結構設計的注意事項 28
5 傾斜機構設計計算 28
5.1傾斜機構設計概述 29
5.2傾斜機構設計 29
5.2.1傾斜油缸受力分析及負荷計算 30
5.2.2計算傾斜油缸缸徑和活塞桿直徑 30
5.2.3計算油缸行程 30
5.2.4計算油缸作用時間 31
5.2.5穩(wěn)定性校核 31
5.2.6油缸壁厚的計算 32
5.2.7活塞桿強度計算 33
5.2.8缸體螺紋連接計算 33
5.2.9 缸底厚度及缸底的焊縫強度計算 33
結論 34
參考文獻 35