CA6150車床主軸箱箱體工裝工藝及夾具設計
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太湖學院
機械加工工序卡片
產品型號
零件圖號
0923089
產品名稱
零件名稱
主軸箱箱體
共4頁 第1頁
詳見機械加工工序卡片附圖
車 間
工序號
工序名稱
材料牌號
機加工車間
鉆前端孔
HT200
毛坯種類
毛坯外形尺寸
每毛坯可制件數(shù)
每臺件數(shù)
鑄件
860×647×545
1
1
設備名稱
設備型號
設備編號
同時加工件數(shù)
搖臂鉆
Z35Z3063X20
1
夾具編號
夾具名稱
切削液
0923089-423-1
鉆夾具
工位器具編號
工位器具名稱
工序工時
準終
單件
工步號
工步內容
工步設備
主軸轉速r/min
切削速度mm/min
進給量mm/r
背吃刀量mm
進給次數(shù)
機動
輔助
1
按圖示將工件水平放入夾具體內,可靠定位并夾緊。
36呆扳手
描 圖
2
鉆IX孔系的Φ23孔,通,表面粗糙度12.5,再鉆VIII孔系的2-Φ23孔,通,表面粗糙度12.5。
Φ23加長專用鉆頭,快換轉套,150×0.02帶深度游標卡尺
600
1.5
0.5
0.25
1
3
鉆VII孔系的第一層Φ29孔,通,表面粗糙度12.5。鉆VII孔系的第二層Φ27孔,通,表面粗糙度12.5。鉆VII孔系的第三層Φ23孔,通,表面粗糙度12.5。
Φ29錐柄麻花鉆,Φ27、Φ23加長錐柄麻花鉆,快換轉套,150×0.02帶深度游標卡尺
600
1.5
0.5
0.25
1
`
設計
日期
審核
日期
標準化日期
會簽
日期
標記
處數(shù)
更改文件號
簽字
日期
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處數(shù)
更改文件號
簽字
日期
太湖學院
機械加工工序卡片
產品型號
零件圖號
0923089
產品名稱
零件名稱
主軸箱箱體
共4頁 第2頁
詳見機械加工工序卡片附圖
車 間
工序號
工序名稱
材料牌號
機加工車間
鉆前端孔
HT200
毛坯種類
毛坯外形尺寸
每毛坯可制件數(shù)
每臺件數(shù)
鑄件
860×647×545
1
1
設備名稱
設備型號
設備編號
同時加工件數(shù)
搖臂鉆
Z35Z3063X20
1
夾具編號
夾具名稱
切削液
0923089-423-1
鉆夾具
工位器具編號
工位器具名稱
工序工時
準終
單件
工步號
工步內容
工步設備
主軸轉速r/min
切削速度mm/min
進給量mm/r
背吃刀量mm
進給次數(shù)
機動
輔助
4
裝上V、VI孔系的底孔快換鉆套,分別鉆V、VI孔系的第一層Φ23孔,通,表面粗糙度50。再分別換上對應的Φ48、Φ50快換鉆套,擴孔至Φ48、Φ50,表面粗糙度12.5。
Φ23、Φ48、Φ50錐柄麻花鉆,快換轉套,150×0.02帶深度游標卡尺
600
1.5
0.5
0.25
1
描 圖
5
在VI孔系,用Φ50快換鉆套,Φ23用專用鉆頭,鉆第二層Φ23底孔,通,表面粗糙度50。再用Φ50加長鉆頭,擴孔至Φ50,表面粗糙度12.5。
Φ23專用鉆頭,Φ50加長錐柄麻花鉆,快換轉套,
600
1.5
0.5
0.25
1
`
設計
日期
審核
日期
標準化日期
會簽
日期
標記
處數(shù)
更改文件號
簽字
日期
標記
處數(shù)
更改文件號
簽字
日期
太湖學院
機械加工工序卡片
產品型號
零件圖號
0923089
產品名稱
零件名稱
主軸箱箱體
共4頁 第3頁
詳見機械加工工序卡片附圖
車 間
工序號
工序名稱
材料牌號
機加工車間
鉆前端孔
HT200
毛坯種類
毛坯外形尺寸
每毛坯可制件數(shù)
每臺件數(shù)
鑄件
860×647×545
1
1
設備名稱
設備型號
設備編號
同時加工件數(shù)
搖臂鉆
Z35Z3063X20
1
夾具編號
夾具名稱
切削液
0923089-423-1
鉆夾具
工位器具編號
工位器具名稱
工序工時
準終
單件
工步號
工步內容
工步設備
主軸轉速r/min
切削速度mm/min
進給量mm/r
背吃刀量mm
進給次數(shù)
機動
輔助
6
在V孔系,用Φ48快換鉆套,Φ23用專鉆頭,鉆第二層Φ23底孔,通,表面粗糙度50。再用Φ43專用鉆頭,擴孔至Φ48,表面粗糙度12.5。
Φ23、Φ23專用鉆頭,快換轉套,150×0.02帶深度游標卡尺
600
1.5
0.5
0.25
1
7
在II孔系,Φ38加長鉆頭,分別鉆第一、二層Φ38孔,通,表面粗糙度12.5。
Φ38加長鉆頭,快換轉套,150×0.02帶深度游標卡尺
裝訂號
設計
日期
審核
日期
標準化日期
會簽
日期
標記
處數(shù)
更改文件號
簽字
日期
標記
處數(shù)
更改文件號
簽字
日期
太湖學院
機械加工工序卡片附圖
產品型號
零件圖號
0923089
產品名稱
零件名稱
主軸箱箱體
共4頁 第4頁
描 圖
描 校
底圖號
裝訂號
`
設計
日期
審核
日期
標準化日期
會簽
日期
標記
處數(shù)
更改文件號
簽字
日期
標記
處數(shù)
更改文件號
簽字
日期
編號
無錫太湖學院
畢業(yè)設計(論文)
相關資料
題目: CA6150車床主軸箱箱體工裝
工藝及夾具設計
信機 系 機械工程及自動化專業(yè)
學 號: 0923089
學生姓名: 呂 沖
指導教師: 彭 勇(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: CA6150車床主軸箱箱體工裝
工藝及夾具設計
信機 系 機械工程及自動化 專業(yè)
學 號: 0923089
學生姓名: 呂 沖
指導教師: 彭 勇 (職稱:副教授 )
(職稱: )
2012年11月25日
課題來源
該課題來源于無錫騰飛企業(yè)生產實際
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)課題的科學意義
該課題主要是為了培養(yǎng)學生編制機械零件加工工藝、正確選擇金屬切削機床和工藝參數(shù)、開發(fā)和創(chuàng)新機械產品的能力,要求學生能夠結合常規(guī)普通銑床與零件加工工藝,針對實際使用過程中存在的金屬加工機床的驅動及工件夾緊問題,綜合所學的機械理論設計與方法等知識,對高效、快速夾緊裝置進行改進設計,從而實現(xiàn)金屬加工機床驅動與夾緊的半自動控制。
在設計零件機械加工工裝時,在滿足產品工作要求的情況下,應盡可能多的采用標準件,提高其互換性要求,以減少產品的設計生產成本和周期。
(2) 國內外研究狀況、水平和發(fā)展趨勢
工業(yè)設計是人類社會發(fā)展和科學技術進步的產物,從英國莫里斯的“工藝美術運動”,到德國的包豪斯設計革命以及美國的廣泛傳播與推廣,工業(yè)設計經(jīng)過了醞釀,探索,形成,發(fā)展百余年的歷史滄桑。時至今日,工業(yè)設計已成為一門獨立的專業(yè)學科,并且有一套完整的研究體系。
1980年國際工業(yè)設計協(xié)會理事會(ICSID)給工業(yè)作了明確定義:“就批量生產的工業(yè)產品而言,憑借訓練,技術知識,經(jīng)驗及視覺感受,而預示材料、結構、構造、形態(tài)、色彩、表面加工,裝飾以新的品質和規(guī)格,叫做工業(yè)設計。根據(jù)當時的具體情況,工業(yè)設計師應在上述工業(yè)產品全部側面或其中幾個方面進行工作,而且需要工業(yè)設計師對包裝、宣傳、展示,市場開發(fā)等問題的解決付出自己的技術知識和經(jīng)驗以及視覺評價能力時,這也屬于工業(yè)設計的范疇”。
現(xiàn)在,機械加工工藝及夾具隨著制造技術的發(fā)展也突飛猛進。機械加工工藝以各個工廠的具體情況不同,其加工的規(guī)程也有很大的不同。突破已往的死模式。使其隨著情況的不同具有更加合理的工藝過程。也使產品的質量大大提高。制定加工工藝雖可按情況合理制定,但也要滿足其基本要求:在保證產品質量的前提下,盡可能提高勞動生產率和降低加工成本。并在充分利用本工廠現(xiàn)有生產條件的基礎上,盡可能采用國內、外先進工藝技術和經(jīng)驗。還應保證操作者良好的勞動條件。但我國現(xiàn)階段還是主要依賴工藝人員的經(jīng)驗來編制工藝,多半不規(guī)定工步和切削用量,工時定額也憑經(jīng)驗來確定,十分粗略,缺乏科學依據(jù),難以進行合理的經(jīng)濟核算
研究內容
① 根據(jù)提供的畢業(yè)設計資料理解設計要求,查閱相關中外資料。
② 確定CA6150車床主軸箱體的工藝方案。
③ 對鉆床專用夾具進行類型選擇及結構分析。
④ 完成鉆床專用夾具加工工序和裝配圖。
⑤ 閱讀和翻譯英文文獻。
⑥ 撰寫畢業(yè)設計論文。
擬采取的研究方法、技術路線、實驗方案及可行性分析
(1)研究方法
借閱相關書籍雜志,充分利用圖書館及網(wǎng)絡資源。
(2)技術路線
收集資料,確定工藝方案,做定位、夾緊設計。
(3)實驗方案
明確設計要求,認真調查研究,收集設計資料,主軸箱工藝方案,根據(jù)設計要求作出專用夾具的零件圖、裝配圖。
(4)可行性分析
大學里,我學習了機械制圖、機械制造工藝學、機床夾具設計等等,熟悉CAD軟件。在設計中,結合自己所學的知識以及老師的指導,根據(jù)要求,合理選擇主軸箱箱體加工工藝,并且設計出合適的鉆夾具,繪制出零件圖及裝配圖。
研究計劃及預期成果
研究計劃:
2012年11月11日-2012年11月24日:收集資料,撰寫開題報告、文獻綜述;2012年11月25日-2012年12月8日:完成箱體圖紙,確定工藝總體方案;
2012年12月9日-2013年1月21日:完成工藝規(guī)程設計;
2013年3月4日-2013年3月22日:完成夾具的全部零件圖;
2013年3月25日-2013年4月5日:完成夾具的總裝圖;
2013年4月8日-2013年4月19日:完成主軸箱箱體工裝工藝及夾具設計的說明書;
2013年4月22日-2013年4月26日:詳細審閱設計計算、說明書及圖紙并修改;
2013年4月29日-2013年6月5日: 遞交畢業(yè)設計資料,準備答辯材料,并進行答辯。
預期成果:
根據(jù)主軸箱箱體的工裝工藝及夾具設計要求具體分析和理論計算,方案擬定正確;設計計算根據(jù)來源可靠,計算數(shù)據(jù)準確無誤,工藝路線合理;機械結構圖紙繪制要求視圖完整、符合最新國家標準,圖面整潔、質量高(圖紙繪制要求采用計算機繪圖);用CAD完成箱體的零件圖、夾具的零件圖及裝配圖。
特色或創(chuàng)新之處
通過對CA6150車床主軸箱箱體零件的參數(shù)化繪制,大大提高了繪圖速度,節(jié)省了大量時間和避免了不必要的重復勞動,同時做到了圖紙的統(tǒng)一規(guī)范。
已具備的條件和尚需解決的問題
① 可以利用圖書館及網(wǎng)絡資源,已學過CAD的基礎知識;
② 已學的機械理論設計與方法與機械裝備等方面的知識;
③ 工藝路線和夾緊裝置有待進步優(yōu)化設計。
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
Influence factors on the quality of the workplace surface
Processing process on the surface quality of the influence
The vibration of the process system of the influence on the quality of the surface
In mechanical processing process technology system sometimes occur vibration, that is, in the cutting edge tool and workplace is cutting surface except on the name between cutting motion, but also can appear a cyclical relative motion.
Vibration that process system by forming movement of the interference and damage, make processing surface appear chatter marks, increases the surface roughness value, worsening processing surface quality.
Cutter geometrical parameters, materials and cutting quality to the surface quality of the influence
The cutting tool geometric parameters on the surface roughness of the biggest influence is vice PianJiao, the main point PianJiao, arc radius. Under certain conditions, reduce PianJiao, Lord, vice PianJiao point arc radius can reduce surface roughness. Under the same conditions, carbide cutting tools process of surface roughness value less than high speed steel paper cutting knife, and diamond and CBN) tools and better than hard alloy, but because the diamond and iron family affinity materials, it should not be used for processing iron family materials. In addition, the cutting tool before and after the face, cutting knife blade itself directly influence the roughness of the processing the roughness of the surface, therefore, improve the quality of cutting tool, cutting tool and face, cutting knife blade roughness value should be lower than the roughness of the 1 ~ 2 levels.
Cutting fluid to the influence on the quality of the surface
Cutting fluid cooling and lubrication effect can reduce the cutting process of interface friction, reduce the temperature of cutting zone, the cutting metal surface layer of plastic deformation degree down, restrain the develop the thorn and scales produced in the production of different materials for reasonable choice of cutting fluids can reduce the surface roughness.
The workplace material on the surface quality of the influence
The workplace material nature; Processing plastic materials, the cutting tools for metal extrusion produced plastic deformation, and the cutting tool and workplace forced separation of the torn scraps effect, make the surface roughness value increase. The workplace material tenacity the better, metal, plastic deformation, the bigger the processing surface is the more the rough. Processing brittle material in the chip broken granular, due to the collapse in broken and endows the machined surface left many pitted surface roughness.
General toughness large plastic materials, processing after large surface roughness, and toughness of smaller plastic materials, processing to get smaller after the surface roughness. For the same kind of material, the greater the grain size of the organization, the larger the surface roughness. Therefore, in order to reduce the surface roughness, often in cutting processing of material before quenching and tempering or is the fire of treatment to obtain homogeneous fine grain organization and high hardness.
Cutting condition the influence on the quality of the surface
And cutting condition of the relevant process factors, including cutting dosages, cooling lubrication. In low speed processing plastic materials,, easy to produce the develop and scales thorn, so, improve the cutting speed, can reduce the develop and scales thorn, decreasing part already the surface roughness value; For brittle material, general won't form the develop and scales thorn, so, cutting speed on the surface roughness basically no influence. The increase speed, plastic deformation also increases, the surface roughness increases, so, reduce the speed can reduce the surface roughness value, however, feeding reduced to certain value, roughness won't obviously decreased. Normal cutting conditions, cutting depth on the surface roughness the impact is not big, therefore, mechanical process cannot select the too small cutting depth.
Cutting speed on the surface roughness influence
General at the early choose low speed cutting and finishing choose high speed cutting can reduce the surface roughness. In the medium speed cutting plastic materials, due to easy to produce the develop, and plastic deformation is bigger, so after processing parts surface roughness is bigger. Usually by low or high speed cutting plastic material, can effectively avoid the develop of generation, this to reduce table and roughness have positive role.
On the surface quality of the grinding effects
The influence of the grinding wheel grinding wheel granularity the thinner, per unit area grain number grinding, the more of the grinding surface in fine scratches the surface roughness is small; But if too fine granularity, processing to jam wheel it will increase the surface roughness, also easy to produce the ripple and cause burns. The hardness of the grinding wheel should be the right size, its half the longer the better passivation period; The hardness of the grinding wheel is too high, grinding mill is not easy to fall off when grain, make processing surface is of friction, extrusion action intensifies, thus increasing the plastic deformation, making the surface roughness increases, also easy cause burns; But the grinding wheel is too soft, grits too easy to fall off, can make grinding action is reduced, leading to the surface roughness increases, so to select the right grinding wheel hardness. Grinding wheel dressing the higher the quality, the surface of the grinding wheel cutting the blade, cutting the number of all the more the better of the blade contour sex, grinding surface roughness and smaller.
The influence of the grinding wheel speed increase dosage, unit time through the processing of grinding surface grain number increase, each star grits is ground to reduce thickness of the metal, the surface area of the residual reduced; And at the same time, improve the grinding wheel speed can also reduce the workplace material of plastic deformation, these can make processing surface roughness value reduced. Reduce the speed, unit time through the processing of grinding surface grain number increase, the surface roughness decreased; But the low speed, workplace and grinding wheel contact time long, to the quantity of heat of the increasing, opposite will increase the roughness, may also increase surface burn. Increase grinding depth and longitudinal feeding, the plastic deformation increase, will lead to the surface roughness value increase. Radial feeding increase, the grinding process grinding force and grinding temperature will increase, grinding surface plastic deformation degree increase, which will increase the surface roughness. To guarantee the machining quality in the premise of grinding efficiency increase, will require a higher surface the coarse grinding and fine grinding separately, coarse grinding is used when the big radial direction feeding, fine grinding the radial feeding the smaller when, finally without into to grinding, to get the surface roughness of surface is very small.
The workplace material the workplace material of hardness, plastic and thermal conductivity on the surface roughness of big effect. Large plastic soft material easy jam grinding wheel, thermal conductivity poor heat resistant alloy easy for the abrasive early caving, will lead to increased grinding surface roughness.
In addition, because grinding to the high temperature, reasonable use cutting fluids can reduce the grinding of temperature, reduce burns, can also rushed to fall off the grits and scraps, avoid scratch workplace, so as to reduce the surface roughness.
Affect the surface of physical and mechanical properties of factors
Surface layer cold hardening. The cutting edges obtuse radius increased, and the surface of metal the extrusion of enhanced, plastic deformation intensifies, cold hard to strengthen. After cutting tool knife surface wear increases, the knife surface and after processed surface friction intensified, plastic deformation increase, cold hard to strengthen. Cutting speed increase, cutting tool and workplace role time is shortened, make plastic deformation expand the depth decreases, and cold hard layer depth decreases. After cutting speed increase, heat cutting in the surface layer effect time also shortened, will make cold hard degree increase. Feeding increases, cutting force also increased, and the surface of the metal plastic deformation intensifies, cold hard effect is strengthening. The workplace material of plastic is larger and the cold hard phenomenon the serious.
Surface layer material metallographic composition change. When cutting the heat was processing surface temperature of phase change after more than temperature, the surface of the metal microstructure will change. Grinding burns when a surface temperature of phase change to millers temperature above, metal surface microstructure occurred change, make the surface of the metal strength and hardness of the lower, and with residual stress produce appear even microscopic cracks, this phenomenon is called grinding burns. Improve grinding burns grinding heat caused by grinding way is the root of the burn, so improving grinding burns by two ways: one is as far as possible to reduce the generation of grinding heat; 2 it is improved cooling condition, make as far as possible the quantity of heat to produce less workplace. The correct choice grinding wheel reasonable choice of cutting dosages improved cooling conditions.
Surface layer residual stress. Produce residual stress of reason: cutting in processing the metal layer and the surface when there were plastic deformation occurs, the surface of the metal to hematocrit increase; Cutting processing, cutting area will have a lot of heat cutting produce; Different analysis of metallographic organization has different density, also have different olume is necessarily affected by the change of connected the matrix of the metal bar, hence residual stress produce. The main work surface eventually process to the choice of methods. Choose the main parts work surface eventually process method, we must consider the main parts of the specific work surface working conditions and the possible damage to the form. In alternating load, the machine parts on the surface of the local micro cracks, because of tensile stress of action to make primary crack expanding, resulting in parts fracture. Improve parts from the view point of fatigue damage resistance, the final process should choose the surface in the surface produces residual stress processing method. In the machining process, tools on the squash and friction make metal materials happen plastic deformation, cause the original residue area of distortion or groove lines deepened, increases the surface roughness. When the medium or medium low cutting speed cutting plastic material, the surface before the sword in easy to form a high hardness of the devolop, it can take the place of the cutting tool, but state very unstable, the develop generation, grow up and fall off will seriously affect the machined surface roughness value. In addition, in cutting process due to the strong scraps and former knife friction role and tear phenomenon, but also in processing on the surface may produce scale thorn, make processing surface roughness increases.
Grinding surface layer analysis of metallographic organization changes and grinding burns
Mechanical processing produces in the process of heat cutting processing surface of workplace will make the rise of temperature of the violently, when the temperature more than the workplace material metallographic organization changes of the critical temperature, metallographic organization change will occur. In grinding processing, because most grits before cutting Angle is negative, grinding temperature is high, the quantity of heat of generation is much higher than cutting calories at, and grinding heat have 60 to 80% to the workplace, so very prone to the change of metallographic organization, makes the metal surface hardness and strength of decline, produce residual stress and even cause microcracks, this phenomenon is called grinding burns. Produce grinding burns, processing surface often appear yellow, brown, purple, green and burn color, this is grinding surface oxidation of high temperature in instantaneous film under color. Different burns color, shows that the surface of different levels by burns.
Grinding hardened steel, workplace surface layer due to the role of the instantaneous heat, it may produce the following three metallographic organization changes:
If grinding surface layer temperature not over phase transition temperature, but more than martensite transition temperature, then martensite will change to become low hardness of tempering methods, and meanwhile body or body, this call tempering burns.
If grinding surface layer temperature more than phase transition temperatures, the martensite transformation for austenitic, at this time without cutting fluids, the grinding surface hardness fell sharply, surface was annealing, this phenomenon is called annealing burns. When dry grinding is easy to produce this kind of phenomenon.
If grinding surface layer temperature more than phase transition temperature, but have the full cutting fluid on the cooling, the grinding surface layer will be urgent cold forming secondary hardened martensitic, hardness than tempering martensite high, but the surface layer is very thin, and only a few microns thick, under which the low hardness for tempering saxhlet body and saxhlet body, make the surface layer general hardness still reduce, called quenching burns.
Grinding burns improvement measure
Influence factors of grinding burns is grinding dosage, grinding wheel, the workpiece material and cooling conditions. Because grinding heat caused by grinding burns is the root cause of, because this wants to avoid grinding burns, should as far as possible to reduce the heat generated when grinding and decrease as far as possible to the quantity of heat of workplace. Specific can adopt the following measures:
Choosing grinding reasonable dosage cannot use the too big grinding depth, because when grinding depth increases, the plastic deformation is increased, the surface layer and the temperature will increase, burns will also increase; The speed increase, a surface temperature will increase grinding zone, but due to the hot action time reduced, so can reduce the burn.
The workplace material the workplace material grinding zone of the influence of the temperature of depends primarily on its hardness and strength, toughness and thermal conductivity. The workplace material hardness, the higher the strength, toughness, the bigger the grinding work when the more consumption, the quantity of heat that produced the more, the easy generation burns; Thermal conductivity of poor material, also easy to appear in the grinding burns.
The choice of high hardness of the grinding wheel grinding wheel, passivated grits is not easy to fall off, easy to produce burns, so with soft grinding wheel is better; Choose coarse granularity grinding wheel grinding, not easily by grinding wheel grinding jams, can reduce burned; Combine agent of grinding burns also has a great influence, resin combination agent than ceramic combination agent easy to produce burns, rubber binder than resin binder are more likely to have burned.
Cooling conditions for reduction in grinding of temperature, widely used in this cutting liquid cooling. In order to make cutting fluids can injection to the surface, usually the cutting fluid flow increase.
中文譯文
影響工件表面質量的因素
加工過程對表面質量的影響
工藝系統(tǒng)的振動對工件表面質量的影響
在機械加工過程中工藝系統(tǒng)有時會發(fā)生振動,即在刀具的切削刃與工件上正在切削的表面之間除了名義上的切削運動之外,還會出現(xiàn)一種周期性的相對運動。
振動使工藝系統(tǒng)的各種成形運動受到干擾和破壞,使加工表面出現(xiàn)振紋,增大表面粗糙度值,惡化加工表面質量。
刀具幾何參數(shù)、材料和刃磨質量對表面質量的影響
刀具的幾何參數(shù)中對表面粗糙度影響最大主要是副偏角、主偏角、刀尖圓弧半徑。在一定的條件下,減小副偏角、主偏角、刀尖圓弧半徑都可以降低表面粗糙度。在同樣條件下,硬質合金刀具加工的表面粗糙度值低于高速鋼刀具,而金剛石、立方氮化硼刀具又優(yōu)于硬質合金,但由于金剛石與鐵族材料親和力大,故不宜用來加工鐵族材料。另外,刀具的前、后刀面、切削刃本身的粗糙度直接影響加工表面的粗糙度,因此,提高刀具的刃磨質量,使刀具前后刀面、切削刃的粗糙度值應低于工件的粗糙度值的1~2級。?
切削液對表面質量的影響
切削液的冷卻和潤滑作用能減小切削過程中的界面摩擦,降低切削區(qū)溫度,使切削層金屬表面的塑性變形程度下降,抑制積屑瘤和鱗刺的產生,在生產中對于不同材料合理選用切削液可大大減小工件表面粗糙度。
工件材料對表面質量的影響
工件材料的性質;加工塑性材料時,由刀具對金屬的擠壓產生了塑性變形,加之刀具迫使切屑與工件分離的撕裂作用,使表面粗糙度值加大。工件材料韌性越好,金屬的塑性變形越大,加工表面就愈越粗糙。加工脆性材料時其切屑呈碎粒狀,由于切屑的崩碎而在加工表面留下許多麻點使表面粗糙。
一般韌性較大的塑性材料,加工后表面粗糙度較大,而韌性較小的塑性材料,加工后易得到較小的表面粗糙度。對于同種材料,其晶粒組織越大,加工表面粗糙度越大。因此,為了減小加工表面粗糙度,常在切削加工前對材料進行調質或正火處理,以獲得均勻細密的晶粒組織和較高的硬度。?
切削條件對工件表面質量的影響
與切削條件有關的工藝因素,包括切削用量、冷卻潤滑情況。中、低速加工塑性材料時,容易產生積屑瘤和鱗刺,所以,提高切削速度,可以減少積屑瘤和鱗刺,減小零件已加工表面粗糙度值;對于脆性材料,一般不會形成積屑瘤和鱗刺,所以,切削速度對表面粗糙度基本上無影響。進給速度增大,塑性變形也增大,表面粗糙度值增大,所以,減小進給速度可
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