擋環(huán)沖壓倒裝復(fù)合模具設(shè)計(jì)畢業(yè)設(shè)計(jì)-資料下載頁(yè)

【導(dǎo)讀】冷沖壓是在常溫下使板料經(jīng)分離或成形而得到制件的加工方法。術(shù)方面都具有很多優(yōu)點(diǎn)。而沖壓產(chǎn)品質(zhì)量的好壞主要取決于冷沖壓模具。本次設(shè)計(jì)是對(duì)給定的產(chǎn)品圖進(jìn)行沖裁模的設(shè)計(jì)。方案后，進(jìn)行模具的設(shè)計(jì)，并通過(guò)計(jì)算選擇合適的壓力機(jī)。

　　

【正文】 arbon. However, it should be fully understood that any increase of strength over that pure iron can be obtained only at the expense of some loss of ductility, and the final choice is always a promise of some de gree. Because of the difficulty of position control or the additional operation of increasing carbon content, the cost of higher carbon, higher strength steel is greater than of low carbon. Plain Carbon Steels Most Used. Because of their low cost, the majority of steels used are plain carbon steels. These consist of iron bined with carbon concentrated in there ranges classed as low carbon,medium carbon, and high carbon. With the exception of manganese used to control sulphur, other elements are present only in small enough quantities to be considered as impurities, though in some cases they may have minor effect on properties of the material. Low Carbon. Steel with approximately 6 to 25 points of carbo n (%～ %)are rated as low carbon steels and are rarely hardened by heat treatment because the low carbon content permits so little formation of hard magnesite that the process is relatively ineffective. Enormous tonnages of these low carbon steels are processed in such structural shapes as sheet, 洛陽(yáng)理工學(xué)院畢業(yè)設(shè)計(jì)（論文） 37 strip,rod,plate,pipe,and wire. A large portion of the material is cold worked in its final processing to improve its hardness, strength, and surface finish grades containing 20 points or less of carbon are susceptible to considerable plastic flow and are frequently used as deepdrawn products or may be used as a ductile core for casehardened material. The low lain carbon steels are reality brazed, welded, and fed. Medium Carbon. The medium carbon steels (% ～ %)contain sufficient carbon that they may be heat treated for desirable strength, hardness, machinability, or other properties. The hardness of plain carbon steels in this range cannot be increased sufficiently for the material to serve satisfactorily as cutting tools,but the loadcarrying capacity of the steels can be raised considerably, while still retaining sufficient ductility for good toughness. The majority of the steel is furnished in the hotrolled condition and is often machined for final finishing. It can be welded,but is mor e difficult to join by this method than the low carbon steel because of structural changes caused by welding heat in localized areas. High Carbon. High carbon steel contains from 50 to 160 points o f carbon (%～ %). This group of steels is classed as tool and die steel, in which hardness is the principal property desired. Because of the fast reaction time and resulting low hardenability, and its associated danger of distortion or cracking, it is seldom possible to develop fully of heattreathardened plain carbon steel is low pared to that of alloy steels with the same strength, but, even so, carbon steel is frequently used because of its lower cost. ALLOY STEELS Although plain carbon steels work well for many uses and are the cheapest steels and therefore the most used, they cannot pletely fulfill the requirements for some work. Individual or groups of properties can be improved by addition of various elements in the form of alloys. Even plain carbon steels are alloys of at least iron, carbon, and manganese, but the term alloy steel refers to steels containing elements other than these in controlled 洛陽(yáng)理工學(xué)院畢業(yè)設(shè)計(jì)（論文） 38 quantities greater than impurity concentration or, in the case of manganese, greater than %. Alloys Affect Harde nability. Interest in hardenability is indirect. Hardenability is usually thought of most in connection with depthhardening ability in a full hardening operation. However, with the isothermal transformation curves shifted to the right, the properties fing operations, the materially usually air cools. Any alloy generally shifts the transformation curves to the right, which with air cooling results in finer pearlite than would be formed in a plain carbon steel. This finer pearlite has higher hardness and strength, which has an effect on machinability and may lower ductility. Weldability. The generally bad influence of alloys on weldability is a further reflection of the influence on hardenability. With alloys present is a further reflection of the influence on hardenability. With alloys prese nt during the rapid cooling taking place in the welding area, hard, nonductile structures are formed in the steel and frequently lead to cracking and distortion. Grain Size and Toughness. Nickel in particular has a very beneficial effect by retarding grain growth in the austenite range. As with hardenability, it is the secondary effects of grain refinement that are noted in properties. A finer grain structure may actually have less hardenability, but it has its most pronounced effect on toughness。 for two steels with equivalent in the chart as improved toughness. This improved toughness, however, may be detrimental to machinability. Corrosion Resistance. Most pure metals have relatively good corrosion resistance, which is generally lowered by impurities or small amounts of intentional alloys. In steel, carbon in particular lowers the corrosion resistance very seriously. In small percentages, copper and phosphorus are beneficial in reducing corrosion. Nickel bees effective in percentages of about %, and chromium is extremely effective in percentages greater than %,w hich leads to a separate class of alloy steels called stainless steels. Many tool steels,while 洛陽(yáng)理工學(xué)院畢業(yè)設(shè)計(jì)（論文） 39 not designed for the purpose, are in effect stainless steels because of the high percentage of chromium present. LOW ALLOY STRUCTURAL STEELS Certain low alloy steels sold under various trade names have bee n developed to provide a low cost structural material with higher yield strengh than plain carbon