罩壳双直角边弯曲模设计

目 录

一 工艺性分析 ······························································2

1.1工艺性分析 ····························································2

1.1.1零件成形工序图·················································· 2

1.1.2方案选择························································ 2

1.2弯曲件的结构工艺性 ···················································3

1.2.1最小弯曲半径 ····················································3

1.2.2弯曲件的直边高度················································ 3

1.2.3板材弯曲零件的弯曲线与板料的纤维方向的关系 ······················4

1.2.4板材弯曲零件的孔与弯曲线的最小距离 ······························4

1.2.5板材弯曲零件的冲裁件毛刺面与弯曲方向 ····························4

1.3弯曲件回弹值的确定 ···················································4

1.3.1回弹值的计算 ····················································4

1.3.2减少回弹的措施 ··················································4

二 弯曲工艺力的计算 ························································5

2.1弯曲件展开长度的计算 ·················································5

2.2校正弯曲力的计算 ·····················································5

2.3顶件力和压力机的确定 ··················································6

2.3.1顶件力和压料力的计算 ············································6

2.3.2弯曲设备标称压力的选择 ··········································6

三 弯曲模工作部分的设计···················································· 6

3.1凸、凹模的间隙值 ·····················································6

3.2弯曲模工作部分尺寸计算 ···············································7

3.3凸、凹模圆角半径 ······················································8

3.3.1凸模圆角半径pr·················································· 8

3.3.2凹模圆角半径dr················································· 8

3.4凹模深度的选取 ·······················································8

3.5凹模高度及壁厚 ·······················································9

四 冲压设备的选择 ··························································9

五 模具的结构件设计······················································· 10

5.1模架 ·································································10

5.2操作方式选择 ·························································10

5.3材料送进和定位方式选择 ···············································10

5.4卸料装置的选择 ·······················································11

5.5导向装置的选择 ·······················································11

5.5.1导套结构尺寸 ···················································11

5.5.2导柱的结构尺寸··················································12

5.6模柄的选用 ···························································12

5.7橡胶的选择和计算 ·····················································13

参考文献 ····································································16

罩壳双直角边弯曲模设计

一 工艺性分析

1.1工艺性分析

1.1.1零件成形工序图

图1.1 工序图

1.1.2方案选择

(1) 方案的比较

分析冲件的外形，可采用的设计方案有：

a. 单工序模 即 冲孔模；落料模；一次弯曲模

b. 冲孔、落料连续模；一次弯曲模

c. 冲孔、落料、弯曲连续模

d. 冲孔、落料复合模；一次弯曲模

(2) 方案的选择

由于此工件表面有孔，需校核先冲孔还是在弯曲后在冲孔。弯曲半径的中心与孔边的距离必须大于料厚的1.5倍以上，可先冲孔。即孔边距tS5.1 经校核所有的孔都可以先进行冲孔再弯曲。由于工件大批量生产，又考虑到工件板料厚度和尺寸的问题，采用第二套方案。

即：冲孔、落料连续模；弯曲模

对此套方案的说明如下：

冲孔：冲出产品件上的几个形孔。

落料：获得产品冲压加工所需要的适当大小的毛坯。

弯曲：在弯曲模的作用下获得产品所需的整体形状。

根据要求，本次设计中需要二套模具来完成，故需设计冲孔、落料连续模和一次弯曲模。

1.2弯曲件的结构工艺性

1.2.1最小弯曲半径

如果弯曲半径过小，弯曲时板料外层拉伸变形量过大，使拉应力达到或超过抗拉强度，则板料外层将出现断裂，致使工件报废。因此弯曲件的最小弯曲半径应不小于表1.1 的数值。

表1.1 最小弯曲半径数值

材料 正火或退火的 硬化的

20 弯曲线方向

垂直纤维 平行纤维 垂直纤维 平行纤维

0.1t 0.5t 0.5t

1.0t

1.2.2弯曲件的直边高度

在进行直角弯曲时，如果弯边过小，弯边在模具上支持的长度过小，不容易形成足够的弯矩，将产生不规则变形，很难得到形状准确的零件。为了保证工件的弯曲质量，必须满足弯曲件的直边高度：H>2t。如下图1.2所示

图1.2

本工件中H8,t1.5，所以符合要求。

1.2.3板材弯曲零件的弯曲线与板料的纤维方向的关系

所选材料碳钢20为冷轧成形，金属在轧制过程中形成了纤维方向（其纤维方向与轧制方向相同），应使板料弯曲线方向与其纤维方向垂直。

1.2.4板材弯曲零件的孔与弯曲线的最小距离

对带孔的工件进行弯曲时，如果孔位于弯曲线附近，弯曲时材料的流动会使原有的孔变形。因此，应当尽量使孔远离弯曲线。孔的边缘距弯曲线的距离l应满足下列关系：

当t<2mm时，lt

符合要求。

1.2.5板材弯曲零件的冲裁件毛刺面与弯曲方向

弯曲件的毛坯是经冲裁落料而成。其冲裁的断面一部分是光亮面，另一面是毛刺面。弯曲件应使其毛刺面作为弯曲件内侧。

1.3弯曲件回弹值的确定

1.3.1回弹值的计算

影响回弹的因素很多，如材料的力学性能，工件的相对弯曲半径r/t，弯曲中心角的大小，弯曲工件的形状，弯曲方式，模具间隙等，因此很难用精确的计算方法得出回弹值的大小，一般是按表格或图表查出经验数值，或按计算法求出回弹角后，再在生产实践中试模修正。20号钢屈服强度为：250MPa属中强度钢。所以根据表“较软金属材料90直角校正弯曲时的角度回弹量”得出20号钢在rt1时的回弹角为（'1~130）。

1.3.2减少回弹的措施

在模具闭合后，再使凸模向下微小移动，利用压力机机身发生弹性变形所产生的力，对工件加压，增加工件塑性变形，以利消除回弹。在模具结构上也应采取措施，使校正力集中于弯角处，增加校正应力，迫使弯曲处内层的金属产生切向拉伸应变，以达到克服和减少回弹的目的。

二 弯曲工艺力的计算

2.1弯曲件展开长度的计算

展开长度一般根据毛坯与工件体积相等的原则，并考虑弯曲处材料变薄的情况，进行计算。计算公式如下：

L=a+b+c+0.6t=8+32+8+0.61.5=48.9mm

2.2校正弯曲力的计算

对于U形弯曲如图2.1所示，如果弯曲件在冲压行程结束时受到模具的校正，则用校正弯曲力计算

图2.1 校正弯曲的示意图

校正弯曲力的公式： P=Fq校

式中：校——校正弯曲力（牛顿）；

F——校正部分投影面积（毫米2）；

q——校形单位压力（兆帕）

查得 ：100qMPa

弯曲的校正弯曲力： 915.110091.5校