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    金属加工中表面粗p度~陷的生与排除分析
    2017-05-18
     

    在金属加工中Q?/span>表面_糙度缺陷严重媄响金属加工质?/span>Q?/span>而表面粗p度~陷产生的机理与各方面粗p度~陷的排除方法值得我们深入研究q不断完?/span>?/span> 表面_糙度是衡量零g表面质量的标?/span>Q?/span>对于零g的美?/span>?/span>接触面摩?/span>?/span>贴合面密?/span>?/span>旋{件疲力_度等{都有着不同E度的媄?/span>?/span>在零件设计和刉的q程?/span>Q?/span>要确定ƈ保证零g的表面粗p度{?/span>但是在实际金属加工过E中Q?/span>会因为刀?/span>?/span>工艺?/span>润滑{多斚w原因造成零g表面_糙度生缺?/span>Q?/span>零g的粗p度达不到要求就可能D零g报废Q?/span>所以必d零g_糙度缺陯行相应的排除办法研究?/span>

     

     

     
     

    一、金属加工过E中常见_糙度缺陷生分?/span>

     

     

     

    1.刀痕粗p分析?/section>
     

     

    刀痕粗p缺陷一般多体现在加大切割进l量的时?/span>Q?/span>主要是由于在切削q程?/span>Q?/span>׃刀具Ş状得金属加工表面部分金属未切除Q?/span>D留在加工表?/span>Q?/span>UC为刀?/span>?/span>

     

    2.鳞刺现象?/section>
     

     

    一般在切削速度较低Q?/span>q且q用高速钢或硬质合金刀具对塑性金属材料进行切削时Q?/span>Ҏ在表面出现鳞片状的裂口和毛刺Q?/span>q种现象UC为鳞刺现?/span>?/span>一般在拉削?/span>插削?/span>滚ɽ{加工过E中Ҏ出现q种情况。当处在低速度?/span>前角刀具切削塑性材料时Q?/span>会Ş成挤裂切屑的情况Q?/span>q就造成刀与屑间生力的作?/span>Q?/span>q周期性地变化Q?/span>q得金属积?/span>Q?/span>加工表面出现断裂和鳞刺现?/span>?/span>

     

    3.划伤和拉毛?/section>
     

     

    划伤和拉毛在_糙度缺L别里也比较常?/span>Q?/span>齿轮加工q程中的啃现象?/span>削加工的拉毛等{?/span>Q?/span>都是划伤和拉毛的代表性现?/span>?/span>而我们可以根据划伤和拉毛的痕qҎ?/span>Q?/span>对它们的产生原因q行分析Q?/span>以求制定好排除措?/span>?/span>

     

    4.刀׃匀?/section>
     

     

    针对于刀׃匀现象Q?/span>主要原因q是在于机床Q?/span>主要表现是金属交工表面的刀具切削痕q不均匀?/span>

     

    5.高频振纹?/section>
     

     

    在金属加工过E中Q?/span>整个工艺pȝ都会随之振动Q?/span>机床?/span>刀?/span>?/span>工g都会寚w属零件表面粗p度有很大的影响?/span>其中工艺pȝ的低频振动一般在工g表面上生LU度Q?/span>而工艺系l高频振动生的振纹则属_糙度范?/span>?/span>工艺pȝ的振动主要包括受q振动和自激振动?/span>受迫振动是由于受周期性外力的作用而生的振动?/span>自激振动则是pȝq动自nȀ发的振动Q?/span>最常见的自Ȁ振动是切削自?/span>?/span>

     

     
     

    二、金属加工过E中常见_糙度缺h除分?/span>

    1.刀痕排除分析?/section>
     

     

    首先切削?/span>Q?/span>应选择允许范围内较的q给?/span>Q?/span>但进l量不能太小Q?/span>不然也媄响切削的_糙?/span>?/span>其次Q?/span>刃磨刀L时?/span>Q?/span>要在允许范围内适当增大刀圆弧半?/span>Q?/span>对粗p度会有一定裨?/span>?/span>

     

    2.鳞刺现象排除分析?/section>
     

     

    首先要把控切削速度?/span>鳞刺现象的生在一定程度上是由于切削速度的原?/span>Q?/span>出或低于特定速度范围Q?/span>都会产生鳞刺现象?/span>其次是切削厚?/span>Q?/span>要尽量减切削厚?/span>Q?/span>切削厚度的增?/span>Q?/span>对于切屑和刀具前面之间的压力会越来越?/span>Q?/span>如果形成挤裂切屑或单元切?/span>Q?/span>会鳞刺现象出现得更频繁和严?/span>?/span>另外采用质量较好的切削液也能有效抑制鳞刺现象的?/span>?/span>合理地选择刀L角度Q?/span>也是排除鳞刺现象的有效方?/span>?/span>最后要对工件材料的切削加工性不断改?/span>Q?/span>比如Q?/span>在某些情况下Q?/span>可以Ҏ料进行加热处理后再进行切?/span>Q?/span>q样鳞刺现象也会减少产生?/span>

     

    3.划伤和拉毛排除分析?/section>
     

     

    划伤和拉毛如果痕q分布比较规?/span>Q?/span>一般是因ؓ机床出现问题Q?/span>机床中如主u?/span>?/span>溜板?/span>、进l箱{传l系l中轴弯?/span>?/span>齿轮齿合不良或者损?/span>Q?/span>都会出现规律的划伤和拉毛现象Q?/span>所以要定时查机?/span>Q?/span>l常q行l修保养?/span>

    如果划伤和拉毛的痕迹分布不规?/span>Q?/span>那么可能与切?/span>、刀?/span>?/span>切削液有关系?/span>比如在深孔加工过E中Q?/span>排屑不畅׃造成内表面划?/span>?/span>工g表面拉毛Q?/span>一般是在磨削过E中׃粒?/span>屑pD?/span>Q?/span>也可能是砂轮不合?/span>?/span>切削液不清洁Q?/span>所以要选择合适的砂轮和清z的切削?/span>?/span>

     

    4.刀׃匀排除分析?/section>
     

     

    刀׃匀的原因有多种Q?/span>但常见的例如在磨削外圆时Q?/span>零g的表面会出现螺旋U性痕q?/span>?/span>q是׃砂轮母线的直U度误差较大所D?/span>Q?/span>q就要求我们在砂轮选择和维护保M规律地做好工?/span>?/span>另外Q?/span>例如机床工作台或者刀架出现爬?/span>Q?/span>也会引v走刀不均匀Q?/span>所以对于机床的?/span>?/span>l护一定要做到?/span>Q?/span>以最大程度地做到预防和避?/span>?/span>

     

    5.高频振纹排除分析?/section>
     

     

    消除高频振纹的主要方法是扑և振源Q?/span>消除振动Q?/span>或把振动减至允许的范围内?/span>

    例如Q?/span>׃零g旋{不^衡引L振动Q?/span>机床传动pȝ引v的振动等{?/span>Q?/span>都是属于受迫振动Q?/span>可以通过扑և振源Q?/span>调整q修理好机床Q?/span>大体可以排除振动媄?/span>Q?/span>同时振纹也会随之消失?/span>而如果是切削自振Q?/span>q种q动是存在于整个切削q程中的Q?/span>q就要对机床?/span>刀?/span>?/span>工g整个工艺pȝ一赯行调?/span>Q?/span>比如改变切削用量?/span>合理选择刀L几何参数?/span>合理Ҏ刀具和工g?/span>调整机床间隙?/span>提高机床的抗振性等?/span>

     

     
     

    三、ȝ

     

     

    通过对R床加工中常见_糙度缺L研究及分?/span>Q?/span>扑և切削中媄响表面粗p度的因?/span>Q?/span>q找出相应的措施和排除方?/span>Q?/span>一斚w可在加工前防患于未然Q?/span>另一斚w在出现问题时能及时准地扑ֈ问题原因Q?/span>及时予以解决Q?/span>对于提高产品质量?/span>促进互换性生产有着现实的意?/span>?/span>


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