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外文翻译 of of of of of in of by in of by an by of in of of is as or of , or of of or in of of of is as of in or of of is to of As to 1 in of at of of of ) z0 ls+3/4) ) z0 hs+2/3) 0z 1 of to of a b c he of +（） in cp of z of a to of to is it of to in to be 1 to of on of to of of by of It is in in 1 1 ) as by sz of is it () , of is it it to be 5 of to to is it (15 , ) , of of to ts . 020. 05it T3 T6 as In of be it to in to of at of is it to at of of at of of to is it of of to On as to is it of of of of to to on of of in so to in of of of 2 in In in to of a Lm is of of of in to , in to a 2 of of . is of so as to is it to on of of of a of of as （ of it to in （ +） of （ +） is it of on a to be is in to of + + is it of to =+D) of it to in (s+c (7) to by to of of is of of a at to on or to as of or of it is to in in t at is it is it to to a as as it is if is to a is is it is it is it to to go on to of of to in in to of a Lm is of in to D is in to a 3 of of . 2. t is 3 of a of of is lm=+) of lm=+1+ of (1+ (8) is it of on a to be is in to of z+ (9) D=(z+ (10) to by to as of of is of of of is at to on or to it is to it is to of as is or on a of of it of in t at is it is it to to is it is it of of to to as as is is it is it to go on to to a of in of of or be is in of it it to be it in on to at t of 4 of of of an be of a of 4 he on a of s+1+on m=(1+ (11) 4 (is in to of (12) To is of on at in of , of at in 5 of hm=z=(1+z on (1+z (13) 5 of of an in in 5, is in of at is in to ) of (14) or of m= (15) It as (z/2)+ (16) Dj it to as j at 0 6 1%, 0. 6% of 6 to of 7 8 7 of o of c of at z/2, it it is ig.s to by of 16 of 780+0. 1956. 370+0. 10mm is it to go as at c)(1=( =16 c)(1=( =6 It of of of of t be to is 6 a of 490+0. 1024. 140+0. 08mm is (1=5( =6 (1=4( =4 It of a of of of t be to To it is of is c of At z/2, of 36 to to 8 3060mm 6. 14060mm is z+(1=( =he is is z+(1=( =c)(1=(1 =6 校核证明该公式所确定的型腔径向尺寸不能满足设计要求。同理对模具型腔深度尺寸 则有 (1=5(1 =6 (1=4(1 =4 校核证明该公式所确定的型腔深度尺寸不能满足设计要求。 对于型芯来 说 ,当型芯制造时是以最小极限尺寸 ,磨损量达到极限磨损量即制造公差的 z/2 时 ,生产出的塑件的型芯最小 ,就有可能超差 ,现对如图 8 所示按平均收缩率计算模具型芯径向尺寸 则有 z+(1=(1 = 36 z+(1=(1 =16 校核证 明该公式所确定的型芯径向尺寸不能满足设计要求。 对型芯高度尺寸 行校核 ,则有 z+(1=(1 =4 型芯高度尺寸校核合格。 z+(1=(1 =8 型芯高度尺寸校核不合格。 从以上的计算分析可以看出 ,采用平均收缩率计算得到的计算结果 ,在收缩率变化范围较大、成型塑件的尺寸较大的情况下出现模具成型尺寸的计算结果往往超差的 ,这种超差现象常常被设计者所忽略或者根本没有意识到。这样就会使所设计的模具不能满足设计和使用要求。 现在用极限公差的方法对该塑件的模具成型尺寸进行设计计算 ,首先对各成型尺寸的公差进行确定 ,对于径向尺寸 ,型芯和型腔都有 : D=(s+c 则模具校核合格 ,能够达到设计要求 ,由此可以确定 值。当选用收缩率波动过大的材料时 ,确定的 算值过小 ,机械加工难以达到设计要求时 ,就可以在设计 过程中及时更换塑件材料 ,选取和采用收缩率波动小的塑料原料来满足高精度塑件的要求。 对于型芯高度尺寸和型腔深度尺寸 ,由于磨量可以忽略不计 ,它们都有 : D=(s+ 则模具校核合格 ,能够达到设计要求 ,由此可以确定 设最大磨损量 得到如图 9和图 10所示的模具成型尺寸及公差图。 图 9极限公差计算模具型腔尺寸 图 10极限公差计算模具型芯尺寸 现对图 9 中各尺寸进行校核 ,可知塑件可能现的最大尺寸是否在允许的尺寸公差规定范围内 ,径向尺寸可由下式进行校核 : c)(1=(1 116 核尺寸合格。 c)(1=(1 =核尺寸合格。型腔深度尺寸可由下式进行校核 : =6 核尺寸合格。 =4 核尺寸合格。 同理 ,对图 10 中模具型芯中的各尺寸进行校核 ,知塑件可能出现的最小极限尺寸也在允许的尺寸公差规定范围之内。 由此可见 ,在进行模具成型尺寸的设计计算过 程中 ,当塑件材料的收缩率波动较大 ,同时塑件的尺 寸中等或较大时 ,由收缩率波动引起的公差变化幅 度较大 ,采用平均收缩率计算得到的结果往往出现超差现象。因此 ,应采用最大、最小收缩率和极限公差分析所得到的成型尺寸的计算公式和校核公式进行尺寸的计算和校核 ,这样就可以准确地对模具成型工作尺寸的公差进行确定 ,当 公差过小 ,加工困难时 ,可以更换材料 ,选取和采用收缩率波动小的塑料满足高精度塑件的要求 ,保证在设计阶段就能发现模具在成型尺寸方面的问题 ,减少模具的返修率。 参考文献 : 1彭建声 ,秦晓刚 M机械工 业出版社 ,2000. 2范德梁 M辽宁科学技术 出版社 ,1983. 3成都科技大学 M中国轻工 业出版社 ,1992. 4马金骏 修订本 )M中国科 学技术出版社 ,1994. 5杨世英 ,陈栋传 册 M机械工业出版社 ,1994
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