ZL50裝載機總體及工作裝置設計
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編號
無錫太湖學院
畢業(yè)設計(論文)
相關資料
題目: 多向固定支架冷沖壓工藝
及級進模設計
機電 系 機械工程及自動化專業(yè)
學 號: 0923235
學生姓名: 裴永勝
指導教師: 鐘建剛(職稱:副教授 )
(職稱: )
2013年5月25日
目 錄
一、畢業(yè)設計(論文)開題報告
二、畢業(yè)設計(論文)外文資料翻譯及原文
三、學生“畢業(yè)論文(論文)計劃、進度、檢查及落實表”
四、實習鑒定表
無錫太湖學院
畢業(yè)設計(論文)
開題報告
題目: 多向固定支架冷沖壓工藝
及級進模設計
信機 系 機械工程及自動化 專業(yè)
學 號: 0923235
學生姓名: 裴永勝
指導教師: 鐘建剛 (職稱:副教授 )
(職稱: )
2012年11月20日
課題來源
來自于無錫海諾有限公司,是電器產品上的一個零件。
科學依據(jù)(包括課題的科學意義;國內外研究概況、水平和發(fā)展趨勢;應用前景等)
(1)課題科學意義
模具產業(yè)是國家經濟基本產業(yè),據(jù)統(tǒng)計金屬零件粗加工的75%,精加工的50%和塑料零件的90%都是用模具加工完成的。用模具成型的制件所表現(xiàn)出來的高精度,高復雜性,高一致性,高生產率,和低消耗,是其他制造加工方法所無法比擬的。模具工業(yè)的發(fā)展水平標志著一個國家工業(yè)水品及產品開發(fā)能力。
沖壓生產靠模具與設備完成其加工產品,生產率高,操作簡便,易于實現(xiàn)機械化與自動化,可以獲得其他方法不能或難以制造的復雜零件。沖壓產品一般不需要再經機械加工就可使用,沖壓加工過程一般也無需加熱毛肧。所以沖壓加工不但節(jié)約金屬材料還節(jié)約能源,沖壓產品一般還具有質量輕和剛性好的特點。
沖壓模具的設計是沖壓生產的基礎,是沖壓生產必不可少的工藝裝備。沖壓設計的水平標志著沖壓生產工藝的先進性合理性以及生產成本的經濟性,他在很大程度上反映了生產技術水平。沖壓件的質量,生產效率以及生產成本等,與沖壓模具設計與制造有根本關系。
(2)研究狀況及其發(fā)展前景
我國沖壓模具的質量和生產工藝水平總體要比國際先進水平低許多,而模具生產周期卻要比國際先進水平長很多。產品質量水平低,主要表現(xiàn)在精度,表面粗糙度,壽命及模具的復雜程度上。生產工藝水平低主要表現(xiàn)在加工工藝和加工裝備等方面。模具壽命只有國際先進水平的50%左右,大型,精密,技術含量高的沖壓模具和精密沖裁模具每年都要花大量資金進口。但一些低檔次的沖模以供過于求,市場競爭非常激烈。
模具技術的發(fā)展是模具工業(yè)發(fā)展的最關鍵的一個因素,其發(fā)展方向應該為適應模具產品“交貨期短”,“精度高”,和“價格低”的要求服務。未來我國模具工業(yè)和技術主要發(fā)展方向應主要集中在以下幾個方面:
1.模具CAD/CAE/CAM集成化,三維化,智能化
2.模具檢測加工設備向高效精密多功能發(fā)展
3.快速經濟制造技術的廣泛應用
4.開發(fā)新的模具材料和表面處理技術
5.模具研磨拋光向自動化智能化發(fā)展
6.模具工業(yè)新工藝,新理念,新模式的發(fā)展。
研究內容
本課題主要圍繞多項固定支架的連續(xù)模設計,重點在于沖壓工藝、排樣方案的設計。根據(jù)所設計的尺寸選擇模具的零件和模架的大小。對于學習模具設計的學生具有實踐和理論結合的教學意義。
擬采取的研究方法、技術路線、實驗方案及可行性分析
根據(jù)多項固定支架的外形,安排沖壓工藝,采取先沖孔,后落料的連續(xù)模沖壓工藝。排樣方案選用最普通的直排,
實驗完全由計算數(shù)據(jù)決定整套模具裝配圖及其零件圖的優(yōu)劣,完全以數(shù)據(jù)為依據(jù)進行的實驗分析,對于整套設計有完整的設計思路,具體的設計計算完全可以通過查表或者公式書籍可以獲得,完全有可行性。
研究計劃及預期成果
研究計劃:
2012年11月12日-2012年12月2日:按照任務書要求查閱論文相關參考資料,填寫畢業(yè)設計開題報告書。
2012年12月3日-2013年3月1日:工作計劃、進度。
2013年3月4日-2013年3月15日:查閱參考資料,學習并翻譯一篇與畢業(yè)設計相關的英文材料。
2013年3月18日-2013年4月12日:沖壓工藝設計,模具結構設計,刃口尺寸和主要零件結構設計和尺寸計算。
2013年4月15日-2013年5月3日:繪制模具裝配圖和零件圖。
2013年5月6日-2013年5月25日:工藝文件、畢業(yè)論文撰寫和修改工作。
預期成果:
1.完成模具裝配圖:2張(A0或A1);
2.零件圖:主要非標準件零件圖(不少于5張);
3.冷沖壓工藝卡片:1張;
4.設計說明書:1份;
5.翻譯8000以上外文印刷字符或譯出約5000左右漢字的有關技術資料或專業(yè)文獻,內容要盡量結合課題。
特色或創(chuàng)新之處
沖壓加工的產品壁薄重量輕,可以形成形狀復雜的零件。生產效率高,生產過程易實現(xiàn)機械化和自動化,適合大批量生產。加工產生的切削少甚至無,零件直接成型,材料利用率高。
已具備的條件和尚需解決的問題
已具備的條件:
擁有模具設計的一定基礎,知道模具結構,能夠根據(jù)模具所需選擇需要的零件。擁有一些關于模具設計方面的資料。
尚需解決的問題:
對設計的每個環(huán)節(jié)考慮不是很周全。連續(xù)模結構因素設計連續(xù)模時,要準確掌握加工速度、沖材材質、沖壓力、工位數(shù)、模具間隙等各主要因素,否則就不能發(fā)揮模具的效用和綜合加工方法,特別是在高速沖壓精密件時,模具損傷多,工件精度低,得不到滿意效果。
指導教師意見
指導教師簽名:
年 月 日
教研室(學科組、研究所)意見
教研室主任簽名:
年 月 日
系意見
主管領導簽名:
年 月 日
英文原文
Improving Performance of Progressive Dies
Progressive die stamping is a cost-effective and safe method of producing components. Careful design and construction of dies will ensure optimum performance.
A progressive die performs a series of fundamental sheet metal operations at two or more stations in the die during each press stroke. These simultaneous operations produce a part from a strip of material that moves through the die. Each working station performs one or more die operations, but the strip must move from the first station through each succeeding station to produce a complete part. Carriers, consisting of one or more strips of material left between the parts, provide movement of the parts from one die station to the next. These carrier strips are separated from the parts in the last die station.
There are six elements that should be addressed when designing and building a progressive die to maximize its performance:
· Interpreting the part print,
· Starting material into the die,
· Part lifters and part feeding,
· Flexible part carriers,
· Upper pressure pads, and
· Drawn shells.
Interpreting the Part Print
The first step in the proper design of a progressive die is to correctly analyze the part print. The tool designer must interpret the print to determine the function of the part by looking for such things as the type of material, critical surfaces, hole size and location, burr location, grain direction requirements, surface finish and other factors.
The die designer must understand the part well, particularly if it has irregular shapes and contours. However, modern computer-drawn prints make this more difficult because computer-drawn part data can be downloaded directly to the die-design computer. As a result, the designer may not become thoroughly familiar with important part features.
Also, many computer-drawn parts are more difficult to understand, because often, only one surface is shown and it may be the inside or outside surface. Computer drawings often show all lines, including hidden features, as solid lines instead of dotted lines. This leads to interpretation errors, which in turn leads to errors in the building of the die.
To better understand complex part shapes, it is helpful to build a "sight" model of the part using sheet wax, rubber skins or wood models. Dimensional accuracy is not critical for these models, as they are used primarily to visualize the part. Rubber skins and sheet wax also can be used to develop preform shapes and to develop the best positions for the part as it passes through each die operation in the progressive die.
Starting Material in the Die
Care must be taken to ensure that the strip is started correctly into the die. Improper location of the lead end of the strip will do more damage to the die in the first 10 strokes of the press than the next 100,000 strokes. "Lead-in" gauges must have large leads and a ledge to support the lead end of the coil strip when it is inserted into the die. Large leads on the gauges are important so that the die setup person does not have to reach into the die, as well as for minimizing the time required to start a new strip into the die. Also, one gauge should be adjustable to compensate for variation in strip width,.
The position of the lead edge of the strip is critical for the first press stroke, and must be determined for every die station to ensure that piercing punches do not cut partial holes in the lead edge. This could cause punch deflection or result in a partial cut with trimming punches, which can result in an unbalanced side load as the strip passes through the die. Any of these conditions can result in a shift of the punch-to-die relationship that may cause shearing of the punches.
Improper location of the lead edge of the strip also can result in an unbalanced forming or flanging condition that can shift the upper die in relation to the lower die. Heels should be required to absorb this side load, particularly when forming thick materials.
A pitch notch and pitch stop can provide a physical point to locate and control the lead edge of the strip. Brass tags or marker grooves also can provide a visual location, but these are not as accurate or as effective as a pitch notch stop. The press can be prevented from operating with either a short feed or over feed by mounting the pitch stop on a pivot and monitoring it with a limit switch.
Part Lifters and Part Feeding
Progressive dies often require the strip to be lifted from the normal die work level to the feed level before strip feeding takes place. This can vary from a small amount--to clear trim and punching burrs--to several inches to allow part shapes to clear the die.
Normally, all lifters should rise to the same height so that the strip is supported in a level plane during forward feed. The strip must not sag between lifters; otherwise parts will be pulled out of their correct station location spacing. Bar lifters provide good support and are better than spring pins or round lifters notched on one side of the strip.
Often, a good bar lifter system allows higher press speeds because feed problems are eliminated. Although the initial cost is more than round lifters, performance is better and setup time is reduced.
As the strip is started into the lead-in gauges, the strip should be able to feed automatically through all the following die stations without requiring manual alignment in each set of gauges and lifters. The strip also must be balanced on the lifters so that it does not fall to one side during feed. A retainer cap can be mounted on the top of the outside bar lifters. This produces a groove that captures the strip during feed and prevents strip buckling.
Gauging and lifter conditions can be simulated during die design by cutting a piece of transparent paper to the width of the strip. The lead edge of the paper is placed over the plan view of the die design at the location the strip will be for the first press stroke. Then the paper is marked with all of the operations that will be performed at the first die station--for example, notching and punching. The paper strip then is moved to the second station on the drawing and the operations for both the first and second stations are marked. This process is repeated through all the die stations to illustrate what the real part strip will look like when it is started into the die and helps determine the adequacy of gauges and lifters.
To transport the strip from one station to the next in a progressive die, some material must be left between the parts on the strip. This carrier material may be solid across the width of the strip, or may be one or more narrow ribbons of material, see part carriers sidebar.
Many parts require the edge of the blank to flow inward during flanging, forming or drawing operations. This may require the carrier to move sideways or flex vertically, or both, during the die operation. A flexible loop must be provided in the carrier to allow flexing and movement of the blank without pulling the adjacent parts out of position, Fig. 2.
Another concern is the vertical "breathing" of parts in die stations during the closing and opening of the die in the press stroke. For example, vertical breathing takes place between the draw stations of parts requiring more than one draw to complete the part, Fig. 3. Vertical breathing also occurs when a flange is formed "up" in a progressive die station that is adjacent to stations that use upper pressure pads to hold the adjacent parts down.
It is important to consider the flexing of the carrier during the upstroke of the press as well as during the downstroke because the action may be different. This can be simulated in the design stage by making an outline of the cross-section of the part, the pressure pads and the stationary-mounted steels on separate sheets of paper and then placing these sheets on top of each other in layers over the die section views. This will show the relative position of the part as the die closes and during the reverse action as the die ram opens
Part Carriers
A common feature in all progressive stamping dies is the material that transports the parts from station-to-station as it passes through the die. This material is known by various terms, such as carrier, web, strip, tie, attachment, etc. In this instance, we will use the term carrier, of which there are five basic styles:
Solid carrier--All required work can be accomplished on the part without preliminary trimming. The part is cut off or blanked in the final operation.
Center carrier--The periphery of the part is trimmed; leaving only a narrow tie near the middle of the part. This permits work to be performed all around the part. A wide center carrier permits trimming only at the sides of the part.
Lance and carry at the center--The strip is lanced between parts, leaving a narrow area near the center to carry the parts. This eliminates scrap material between parts.
Outside carriers--The carriers are attached to the sides of the part so that work can be done to the center of the part.
One side carrier--The part is carried all the way or part of the way through the die with the carrier on one side only. This permits work on three sides of the part.
The type or shape of the carrier will vary depending on what the part requires as it progresses from station to station in the die. The stock width may be left solid if no part material motion is required during die closure or it can be notched to create one, two or even three carriers between the parts
The carriers can be straight, form a zig-zag pattern or have loops between the parts depending on where attachment points to the part are available or to accommodate whatever clearance may be required by the die tooling. As the part is formed, flanged or drawn into a shell, the carrier may have to move sideways or up and down as the die closes and opens.
When die operations cause the carrier to move, it usually will be required to flex or stretch. Regardless of carrier flexing, their key function is to move the parts close enough to the next station so that pilots, gauges and locators can put the parts into their precise location as the die closes.
If the carrier acquires a permanent stretch, the parts may progress too far to fit on the next station, or in the case that the die has two carriers, one carrier may develop permanent stretch with no stretch in the other carrier. This will create edge camber in the strip, causing it to veer to one side. This results in poor part location.
A stretched carrier can be shortened to its correct length by putting a dimple in the carrier. If a center carrier or one-sided carrier develops camber, the strip can be straightened by dimpling or scoring one side of the carrier. Construct the dimple and scoring punches so that they are easily adjusted sideways for position and vertically for depth.
as it is delivered from the coil can cause the strip to bind in the running gauges that guide the material during the feed cycle. This binding may cause the carriers to buckle, which results in short feeds. It often helps to relieve the guide edge of the gauges in between stations and have tighter gauge control at the work station.
Another option is to eliminate camber by trimming both sides of the material in the beginning of the die. By adding stops at the end of these trim notches they can be used as pitch control notches to prevent progression overfeed.
Optimum Carrier Profile
The optimum carrier profile is affected by some of the following conditions:
· Space available between parts: Try to keep the carriers within the stock width and pitch required for the blank. If this is not possible then the designer must add to the width and/or the progression of the material to provide adequate carrier room.
· Attachment points to the part: If two carriers are used, try to keep the profile and length of the carriers somewhat the same so that any effect of carrier flexing is close to being balanced.
· Clearance for punch and die blocks: Punch blocks that extend below the stock or die blocks that extend above the stock when the die closes will require clearance in relation to the parts and the carriers. If a loop of the carrier interferes with blocks it may be possible to form the loop vertical to provide clearance.
· Thickness of the material: Large parts with thin material may require stiffener beads to add strength to the carrier for stock feeding. Another stiffening and strip guiding method is to lance and flange the edge of the stock, which also can be used as a progression notch.
· The total of the strip: Heavy parts in long dies require more force to push the strip through the die. However, the weight is usually thick material, and thick material is stiffer than thin material. As a rule of thumb, flexible carriers for materials of 0.020 in. to 0.060 in. are about 3/16 in. to 5/16 in. wide. For stock thicknesses above and below this thickness range, carrier width is a "best judgment call."
Depending on all the die factors involved, under normal conditions the carriers should be a consistent width for their full length, but especially in the area of flexing. Since nearly every stock feeder pushes material through the die rather than pull the material, the carrier must be strong enough to push the parts all the way through the die.
A detection switch actuated by a complete feed of the strip at the exit of the die can detect buckling. If action of the die during closure or opening of the press requires the carriers to flex, design the carrier with loops that are long enough to flex without breaking, but still strong enough to feed all the parts to their full progression. If two flex carriers are not strong enough to feed the strip, consider three carriers.
Try to make the radii in flex loops as large as practical. Sharp corners or small radii will concentrate stress of flexing, making it the first point to fracture during flexing of the carrier. Also avoid any steps or nicks in the edges of the carrier.
Upper Pressure Pads
Because of size or function, many progressive dies require two or more pressure pads in the upper die. Each may require a different travel distance to perform the work in the individual die station, such as trimming or forming or drawing.
However, the upper pressure pads often are used to push the material lifters down by pressing against the strip, which pushes the lifters down. In this situation, all of the pressure pads that push material lifters down should have the same travel distance. If the upper pressure pads travel different distances, the strip will not be pushed down evenly. This can pull adjacent parts out of the progression, making it difficult to locate the parts in their proper station position after the feed cycle.
If the part requires a flange to be formed up, the part carrier must have a flex loop to allow for vertical breathing of the part or provide a pressurized punch/pad with the same travel as the other pressure pads. The force required by the pressurized punch/pad has to be adequate to form the flanges up during the downstroke while the punch/ pad is in the extended position. This keeps the strip from breathing vertically as it is pushed down from the feed level to the normal work level.
When the strip reaches the work level, the pressurized punch/pad stops its downward motion while the upper die continues down for punching, trimming, down flanging and other operations. Springs or nitrogen cylinders can be used for pressure in these pressurized punch/ pad stations, but they must have enough preload force to form the flanges up and to collapse the lower gripper pad before the upper punch/ pad recedes
中文譯文
提高級進模性能
級進模是一種成本低廉且安全的零件制造方法,. 精心設計模具結構可確保最佳性能。一副級進模在一次沖壓動作中可在模具不同工位進行不同的沖壓操作。這些在通過模具的帶料上同時進行的沖壓動作制造出零件。每個工位可進行一個或多個操作,但要生產出完整的零件條料必須經過每一個工位。而零件依靠零件之間的載體輸送到各個工位,并在最后一個工位進行切除。
為了使模具性能最佳,在設計和制造級進模具時,必須考慮以下五個方面:
· 研究零件
· 送料方式
· 零件頂出和送進
· 設計零件載體
· 壓料裝置
零件排樣
設計級進模首先必須正確地理解零件圖,必須考慮材料、重要表面、孔的尺寸和和位置、毛刺方向、材料纖維方向、表面粗糙度和其他因素。
模具設計要求設計者必須對零件有透澈的了解,特別是對形狀和輪廓不規(guī)則的零件。然而,現(xiàn)代計算機繪圖使得零件數(shù)據(jù)可以直接下載到設計者的電腦上,使得設計者可能不熟悉零件重要特性。
另外,因為計算機繪圖經常出現(xiàn)這種情況,圖上只顯示一個面,可能是內表面也可能是外表面,使得很多計算機繪制的圖形難以看懂。電腦繪圖經常顯示所有的線條,包括隱藏部分,為實線而非虛線,這導致錯誤,進而導致模具結構錯誤。
為了更好地看懂復雜零件外形,可用蠟板,橡膠皮或者木板做成具有零件某個視圖方向上的外形的模型。模型不要求精確的尺寸,其主要是用來形象地表示零件形狀。也可以用這些模型來決定應該在級進模的哪個工位成形零件哪個部分的外形。
材料送進
必須確保條料準確地進入模具。如果條料導向錯誤,那么最初的10次沖壓動作對模具造成的損傷可能比接下來的100000次沖裁還大。當卷料送進入模具時必須順利導向且有限位裝置。良好的導向能力時非常重要的,因為這樣操作人員就不必將手伸入模具,而且可以縮短接上下一卷材料所需的時間。除此之外,導向裝置必須時可調的以適應條料寬度的變化。對第一次沖裁而言條料送進位置非常重要,必須確定條料在每個工位的送進位置的以保證凸模不沖偏,會導致沖頭變形或切不完整,可能造成條料不平衡送進時單側受力。任一種可能都會造成凸凹模錯位使得沖頭受剪切損壞。
條料送進不當成形時可能導致偏載或者邊緣卷起,影響上下模之間的相對位置。墊塊必須能夠承受這些載荷,特別是成形較厚材料時更應如此。
一個步距的凹口或止動銷可作為定位點控制條料送進位置,黃銅標簽或標記槽也提供了視覺定位 ,但是這些都不夠準確,不夠有效。通過在將步距限位銷安裝在支點上,并用限位開關監(jiān)控以防止條料送進不到位或送進過多以保護壓力機。
零件頂出和送進
級進模通常要求將條料抬高到距模具工作位置一定高度水平線上,使得條料送進到指定位置,而與清理廢料和毛刺或者利用制件外形清理模具無關。
正常情況下,所有抬高裝置必須上升到同一高度使條料在送進過程中保持水平。條料不能由凹陷,否則零件會被從正確位置拔出。相對于安排