模具尺寸的確(que)定(ding)方法

模(mo)(mo)(mo)具(ju)型(xing)(xing)腔和型(xing)(xing)芯的(de)(de)加(jia)(jia)工(gong)尺(chi)寸(cun)(cun)(cun)除了(le)(le)通過D=M(1+S)公(gong)式計算基本尺(chi)寸(cun)(cun)(cun)之外，還有(you)一個加(jia)(jia)工(gong)公(gong)差(cha)(cha)(cha)(cha)(cha)的(de)(de)問題。按照慣例(li)，模(mo)(mo)(mo)具(ju)的(de)(de)加(jia)(jia)工(gong)公(gong)差(cha)(cha)(cha)(cha)(cha)為塑(su)(su)(su)件(jian)(jian)(jian)公(gong)差(cha)(cha)(cha)(cha)(cha)的(de)(de)1/3。但由于(yu)塑(su)(su)(su)料收(shou)縮(suo)率(lv)范(fan)圍(wei)和穩定(ding)(ding)性各有(you)差(cha)(cha)(cha)(cha)(cha)異，首先必(bi)須合理化確定(ding)(ding)不同塑(su)(su)(su)料所成形(xing)塑(su)(su)(su)件(jian)(jian)(jian)的(de)(de)尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)。即由收(shou)縮(suo)率(lv)范(fan)圍(wei)較大或收(shou)縮(suo)率(lv)穩定(ding)(ding)較差(cha)(cha)(cha)(cha)(cha)塑(su)(su)(su)料成形(xing)塑(su)(su)(su)件(jian)(jian)(jian)的(de)(de)尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)應取得大一些(xie)。否則就(jiu)可(ke)能出現大量尺(chi)寸(cun)(cun)(cun)超差(cha)(cha)(cha)(cha)(cha)的(de)(de)廢品。 為此(ci)，各國(guo)對塑(su)(su)(su)料件(jian)(jian)(jian)的(de)(de)尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)專門制訂了(le)(le)國(guo)家標準(zhun)或行(xing)業(ye)標準(zhun)。中國(guo)也曾制訂了(le)(le)部級專業(ye)標準(zhun)。但大都無相(xiang)應的(de)(de)模(mo)(mo)(mo)具(ju)型(xing)(xing)腔的(de)(de)尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)。德國(guo)國(guo)家標準(zhun)中專門制訂了(le)(le)塑(su)(su)(su)件(jian)(jian)(jian)尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)的(de)(de)DIN16901標準(zhun)及相(xiang)應的(de)(de)模(mo)(mo)(mo)具(ju)型(xing)(xing)腔尺(chi)寸(cun)(cun)(cun)公(gong)差(cha)(cha)(cha)(cha)(cha)的(de)(de)DIN16749標準(zhun)。此(ci)標準(zhun)在世界上具(ju)有(you)較大的(de)(de)影響(xiang)，因(yin)而可(ke)供塑(su)(su)(su)料模(mo)(mo)(mo)具(ju)行(xing)業(ye)參考。

關于塑件的尺寸公差和允許偏差

為了合理地(di)確定不(bu)同收縮特性(xing)材料所(suo)成形塑件的(de)尺寸(cun)公差(cha)(cha)，讓標準引入(ru)了成形收縮差(cha)(cha)△VS這一概念(nian)。 △VS＝VSR_VST(4)

式(shi)中(zhong)： VS－成形(xing)收(shou)縮差　VSR－熔料(liao)流(liu)動方(fang)向的(de)成形(xing)收(shou)縮率(lv)　VST－與熔料(liao)流(liu)動垂直(zhi)方(fang)向的(de)成形(xing)收(shou)縮率(lv)。

根據塑(su)(su)料(liao)(liao)△VS值(zhi)(zhi)，將各(ge)種塑(su)(su)料(liao)(liao)的(de)(de)(de)(de)(de)(de)收縮特(te)性(xing)分為(wei)4個(ge)組(zu)(zu)。△VS值(zhi)(zhi)最小的(de)(de)(de)(de)(de)(de)組(zu)(zu)是高(gao)精度組(zu)(zu)，以此類(lei)推，△VS值(zhi)(zhi)最大的(de)(de)(de)(de)(de)(de)組(zu)(zu)為(wei)低精度組(zu)(zu)。 并按照基本尺(chi)(chi)(chi)寸(cun)(cun)(cun)編制了精密(mi)技術(shu)、110、120、130、140、150和(he)(he)160公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)組(zu)(zu)。并規定，用(yong)(yong)(yong)收縮特(te)性(xing)最穩定的(de)(de)(de)(de)(de)(de)塑(su)(su)料(liao)(liao)成(cheng)(cheng)形塑(su)(su)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)可選(xuan)(xuan)(xuan)用(yong)(yong)(yong)110、120和(he)(he)130組(zu)(zu)。用(yong)(yong)(yong)收縮特(te)性(xing)中(zhong)等穩定的(de)(de)(de)(de)(de)(de)塑(su)(su)料(liao)(liao)成(cheng)(cheng)形塑(su)(su)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)選(xuan)(xuan)(xuan)用(yong)(yong)(yong)120、130和(he)(he)140。如果用(yong)(yong)(yong)這類(lei)塑(su)(su)料(liao)(liao)成(cheng)(cheng)形塑(su)(su)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)選(xuan)(xuan)(xuan)用(yong)(yong)(yong)110組(zu)(zu)時(shi)(shi)，即可能出大量(liang)尺(chi)(chi)(chi)寸(cun)(cun)(cun)超差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)塑(su)(su)件(jian)(jian)(jian)(jian)(jian)。用(yong)(yong)(yong)收縮特(te)性(xing)較差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)的(de)(de)(de)(de)(de)(de)塑(su)(su)料(liao)(liao)成(cheng)(cheng)形塑(su)(su)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)選(xuan)(xuan)(xuan)用(yong)(yong)(yong)130、140和(he)(he)150組(zu)(zu)。用(yong)(yong)(yong)收縮特(te)性(xing)最差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)的(de)(de)(de)(de)(de)(de)塑(su)(su)料(liao)(liao)成(cheng)(cheng)形塑(su)(su)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)選(xuan)(xuan)(xuan)用(yong)(yong)(yong)140、150和(he)(he)160組(zu)(zu)。 在使用(yong)(yong)(yong)此公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)表(biao)時(shi)(shi)，還需(xu)注(zhu)意以下(xia)(xia)各(ge)點。 表(biao)中(zhong)的(de)(de)(de)(de)(de)(de)一般公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)用(yong)(yong)(yong)于(yu)不注(zhu)明公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)。直(zhi)(zhi)接(jie)標(biao)注(zhu)偏(pian)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)的(de)(de)(de)(de)(de)(de)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)是用(yong)(yong)(yong)于(yu)對塑(su)(su)件(jian)(jian)(jian)(jian)(jian)尺(chi)(chi)(chi)寸(cun)(cun)(cun)標(biao)注(zhu)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)的(de)(de)(de)(de)(de)(de)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)帶。其上、下(xia)(xia)偏(pian)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)可設計人員自(zi)行確定。例如公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)帶為(wei)0.8mm，則可以選(xuan)(xuan)(xuan)用(yong)(yong)(yong)以下(xia)(xia)各(ge)種上、下(xia)(xia)偏(pian)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)構成(cheng)(cheng)。0.0;-0.8;±0.4;-0.2;-0.5等。 每一公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)組(zu)(zu)中(zhong)均有A、B兩組(zu)(zu)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)值(zhi)(zhi)。其中(zhong)A是由模具零(ling)件(jian)(jian)(jian)(jian)(jian)組(zu)(zu)合形成(cheng)(cheng)的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)，增加了模具零(ling)件(jian)(jian)(jian)(jian)(jian)對合處不密(mi)合所(suo)形成(cheng)(cheng)的(de)(de)(de)(de)(de)(de)錯差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)。此增加值(zhi)(zhi)為(wei)0.2mm。其中(zhong)B是直(zhi)(zhi)接(jie)由模具零(ling)件(jian)(jian)(jian)(jian)(jian)所(suo)決(jue)定的(de)(de)(de)(de)(de)(de)尺(chi)(chi)(chi)寸(cun)(cun)(cun)。 精密(mi)技術(shu)是專門設立的(de)(de)(de)(de)(de)(de)一組(zu)(zu)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)值(zhi)(zhi)，供具有高(gao)精度要求塑(su)(su)件(jian)(jian)(jian)(jian)(jian)使用(yong)(yong)(yong)。 在此用(yong)(yong)(yong)塑(su)(su)件(jian)(jian)(jian)(jian)(jian)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)之前(qian)，首先(xian)必須知道(dao)所(suo)使用(yong)(yong)(yong)的(de)(de)(de)(de)(de)(de)塑(su)(su)料(liao)(liao)適(shi)用(yong)(yong)(yong)哪幾個(ge)公(gong)(gong)(gong)差(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)(cha)組(zu)(zu)。

模具的制造公差

德國國家標準針(zhen)對塑(su)件公(gong)(gong)(gong)差制(zhi)訂了相應(ying)模具(ju)制(zhi)造(zao)公(gong)(gong)(gong)差的(de)(de)(de)標準DIN16749。該表中共(gong)設4種公(gong)(gong)(gong)差。不(bu)論(lun)何種材(cai)料(liao)的(de)(de)(de)塑(su)件，其中不(bu)注明尺(chi)(chi)寸公(gong)(gong)(gong)差尺(chi)(chi)寸的(de)(de)(de)模具(ju)制(zhi)造(zao)公(gong)(gong)(gong)差均使(shi)用序號1的(de)(de)(de)公(gong)(gong)(gong)差。具(ju)體公(gong)(gong)(gong)差值由(you)基本尺(chi)(chi)寸范(fan)圍(wei)確定。 不(bu)論(lun)何種材(cai)料(liao)塑(su)件中等精度(du)(du)尺(chi)(chi)寸的(de)(de)(de)模具(ju)制(zhi)造(zao)公(gong)(gong)(gong)差為(wei)序號2的(de)(de)(de)公(gong)(gong)(gong)差。不(bu)論(lun)何種材(cai)料(liao)塑(su)件較(jiao)高(gao)精度(du)(du)尺(chi)(chi)寸的(de)(de)(de)模具(ju)制(zhi)造(zao)公(gong)(gong)(gong)差為(wei)序號3的(de)(de)(de)公(gong)(gong)(gong)差。精密(mi)技術相應(ying)的(de)(de)(de)模具(ju)制(zhi)造(zao)公(gong)(gong)(gong)差為(wei)序號4的(de)(de)(de)公(gong)(gong)(gong)差。

可(ke)以合(he)理(li)地確定各種材料塑件的(de)合(he)理(li)公差和相應的(de)模(mo)具制造公差，這不僅(jin)給模(mo)具制造帶來(lai)方便，還可(ke)以減少廢(fei)品，提高(gao)經濟效期(qi)益。