Shanghai Daoqin Plastics Co., Ltd.

         currently, in mold manufacturing in, already application electrical processing, molding abrasion 削, 线切割 and other new process, relatively good solution complex mold processing and hot deformation issues. however, this new process due to to various conditions made, can application. therefore, how to decrease/reduce mold hot deformation, currently still is very important issues.

         generally mold requirements degree relatively high, hot 处理以 rear, also 不便于甚至不 can can again processing and positive, therefore, in hot rear, make property can already to requirements, deformation ultra- 差, still 然因无 method 挽救而报 waste, this not only effect/influence production, but also also formed upper loss 失.

         has hot deformation generally 规律, this as 讨论, below/following for effect/influence mold deformation factors as brief analysis.

        一, mold material for hot deformation effect/influence

        材 material for hot deformation effect/influence, 包括钢 chemical formed separation and 原始组织两方面 effect/influence.

         from material 本身 看, main/primary through formed separation for property, Ms点 and other effect/influence effect/influence hot deformation.

         carbon tool in positive 常淬火 temperature degree water -油 di liquid 淬火时, in Ms点 above generate very large hot force;当 cold to Ms点 below/following 时, 奥氏体 toward 马氏体转变, generate 组织应 force, due to carbon tool 钢淬透 property 差, therefore 组织应 force value large. add upper its Ms点不 high, in 发生马氏体组织转变时, 钢 塑 property already very 差, easy 发生塑 property deformation, therefore, 就保留 hot force function formed deformation 特征, mold type toward shrinkage. 但若淬火 temperature degree improve/increase (>850℃), can can 因组织应 force 起主导 function, make type toward large.

         in use 9Mn2V, 9SiCr, CrWMn, GCr15钢 and other low alloy tool made as mold 时, its deformation and carbon tool versus 似, deformation amount need ratio carbon tool need small.

         for/regarding high alloy 钢, 如Cr12MoV钢 and other, due to its carbon and alloy content relatively high, Ms点 relatively low, 因而淬火 rear has relatively more 残余奥氏体, it for due to 马氏体而致 体积膨胀 has function, therefore, rear deformation versus small, generally use cold, cold, salt 浴淬火时, mold type 腔趋于 micro amount large;若淬火 temperature degree high, 则残余奥氏体 amount increase, type can can shrink small.

        若 use carbon structure 钢(如45钢) or certain alloy structure 钢(如40Cr) made as mold, its Ms点 relatively high, surface 开始马氏体转变时, temperature degree relatively high, strong/high degree relatively low, has 一定 塑 property, surface for 心部 瞬时 tensile 组织应 force, easy ultra- 心部 屈服 strong/high degree make type toward large.

        钢 原始组织 for deformation has effect/influence. this 里 指 “钢 原始组织”, 包括钢 in material grade 别, belt/tape 状组织 grade 别, formed 份 偏析程 degree, carbon material distribution direction property and other, and due to different hot 处理而 to different 组织(如珠 light 体, 回火索氏体, 回火屈氏体 and other). for mold 钢 说, main/primary is carbon material 偏析, carbon material and distribution 形态.

         high carbon high alloy 钢(如Cr12 type 钢) in carbon material for deformation effect/influence especially obvious. due to carbon material 偏析造 formed add hot 至奥氏体状态 rear formed separation non-uniform property, 因而, different Ms点就会 has high has low. in cooling conditions lower, 奥氏体 toward 马氏体转变就 has has rear, rear 马氏体就因含 carbon amount different ratio has large has small, has low carbon, low alloy can can 根本 不 to 马氏体(而 to 贝氏体, 屈氏体 and other), has this 都会造 formed parts rear non-uniform deformation.

         different carbon material distribution 形态(呈 pellets or fiber distribution), for 基体胀 shrink effect/influence different, 因而也会 effect/influence hot rear deformation, generally is carbon material fiber direction type large, relatively significantly;而垂直于 fiber direction shrink small, significantly, has is as 规定, type in and carbon material fiber direction 垂直, decrease small type deformation, carbon material pellets uniform distribution 时, type performance is uniform shrink.

         in addition, most hot 处理之 front 组织状态 for deformation has effect/influence, 例如, 原始组织 is 球状珠 light 体 就 ratio sheet/slice light in rear deformation toward need small. therefore deformation requirements mold, in coarse processing rear 先进行 one-time 调质处理, rear again 进行精 processing and most hot 处理.

        二, mold 几何形状 for deformation effect/influence

         mold 几何形状 for hot deformation effect/influence, upper still is through hot force, 组织应 force function. due to mold is multiple more 样, need from in summary 出确切 deformation 规律, currently also very difficult.

         for/regarding for type mold, can according to type dimensions, outer dimensions and high degree type deformation toward. mold thin, high degree small 时, relatively easy 于淬透, this has can can is 组织应 force 起主导 function, therefore, type 腔常趋 toward large. 反之, thick, high degree large, easy 淬透, can can is hot force 起主导 function, therefore, type 腔常趋 toward shrink small. this 里 说 is generally trend, in production in, also must combined parts specific 形状, using/adopting types and hot process and other add 以考虑, through 实践不断 summary experience. due to production in, mold outer dimensions 往往不 is main/primary as dimensions, deformation rear also can through abrasion processing and other add positive, therefore upper analysis main/primary is type deformation trend.

         for/regarding for mold deformation, 同样也 is hot force, 组织应 force comprehensive function 结果. 例如, for thin thin mold, due to thin, 淬火时 inner outer temperature small, hot force small;但容 easy 淬透, 组织应 force relatively large, therefore deformation toward type large.

         is decrease small mold deformation, hot 处理部门应 and mold design 部门共同 research, improvement mold design, can can 避免截面 large small versus 差悬殊 mold structure, mold force for 称, complex mold use combined structure and other.

        当不 can mold 形状时, is decrease small deformation, also can 采取一 its it measures. this measures 总 考虑 is improvement cooling conditions, make separation uniform cooling; in addition, can 辅助以 various strong/high made measures, made parts deformation. 例如, increase processing 艺孔, is make separation uniform cooling measures, in mold certain separation 开孔, make mold 各 部 separation uniform cooling decrease small deformation. can in rear easy large mold outer use 石棉包住, increase large inner and outer cooling 差异, make type shrinkage. in mold upper or add is decrease/reduce deformation also types strong/high made measures, it especially suitable for type large 凹模, and easy large or shrink small mold.

        三, hot process for mold deformation effect/influence

        1, add hot speed degree effect/influence

         generally 说, add hot 时, add hot speed degree fast, mold in generate hot force large, easy formed mold deformation cracking, especially for/regarding alloy and high alloy 钢, its thermally conductive property 差, attention/notes preheating, for/regarding 一 形状 complex high alloy mold, also 需采取 more separation grade preheating. in 别情况 lower, using/adopting fast speed add hot has 时反而 can decrease/reduce deformation, this add hot mold surface, in also maintain “ cold 态”, therefore versus decrease/reduce 组织应 force and hot force, 且心部 deformation resistant force relatively large, from decrease/reduce deformation, according to factory experience, used for solution deformation has 一定效果.

        2, add hot temperature degree effect/influence

        淬火 add hot temperature degree high low effect/influence material property, meanwhile for 奥氏体 formed separation and large small function.

        (1) from property 方面看, add hot temperature degree high, will make hot force increase large, meanwhile make property increase high, therefore 组织应 force increase large, 并逐渐占主导 位. 例如. carbon tool 钢T8, T10, T12 and other, in generally temperature degree 淬火时, inner performance is shrink toward, improve/increase temperature degree to ≥850℃时, due to property increase large, 组织应 force 逐渐占主导 位, inner can can performance is 胀 倾 toward.

        (2) from 奥氏体 formed separation 看, temperature degree improve/increase make 奥氏体含 carbon amount increase, rear 马氏体 positive degree increase large (ratio increase large), from make rear increase large.

        (3) from for Ms点 effect/influence fine 看, temperature degree high, 则奥氏体晶粒 coarse large, will make parts deformation cracking toward increase large.

         comprehensive upper 述, for has types, especially is certain high carbon in, high alloy 钢, temperature degree high low obvious effect/influence mold deformation, therefore, positive selection add hot temperature degree is very important.

         generally 说, selection high add hot temperature degree for deformation is has benefits. in effect/influence use property can front lower, is using/adopting relatively low add hot temperature degree. for 一 淬火 rear has relatively more 残余奥氏体 钢号(如Cr12MoV and other), can through adjustment add hot temperature degree, 改变残余奥氏体 amount, adjustment mold deformation.

        3, cooling speed degree effect/influence

        总 说, in Ms点 above increase large cold speed, make hot force significantly increase, make hot force deformation toward increase large; in Ms点 below/following increase large cold speed main/primary make 组织应 force deformation toward increase large.

         for/regarding different types, due to Ms点 high low different, in using/adopting 同一淬火介质时, has different deformation toward. 同一钢 types using/adopting different 淬火介质, due to it cooling can force different, 因而也 has different deformation toward.

        例如, carbon tool in Ms点 comparison low, using/adopting water cold 时, hot force effect/influence 往往占 upper 风;而 using/adopting cold 时, can can is 组织应 force upper 风.

         in production in, mold using/adopting separation grade or separation grade - and other temperature 淬火时, usually 均未完 full 淬透, 故往往以 hot force function is 主, make type 腔趋于 shrinkage, due to this hot force is very large, therefore deformation amount is comparison small. using/adopting water -油 di liquid or 油淬时, hot force relatively large, type shrinkage amount will increase large.

        4, temperature degree effect/influence

        回火 temperature degree for deformation effect/influence, main/primary is due to process in 组织转变 引起. in process in generate “二次淬火” phenomenon, 残余奥氏体转变 is 马氏体, due to formed 马氏体 ratio ratio 残余奥氏体 large, will mold type 腔 胀 large; for high alloy tool 钢如Cr12MoV and other, requirements hard property is using/adopting high temperature 淬火, more 次回火时, one-time 火, 体积就胀 large one-time.

        若 in other temperature degree 区域回火, due to 淬火马氏体 toward 回火马氏体(or 回火索氏体, 回火屈氏体 and other)转变, ratio decrease small, 因而, type toward shrinkage.

         another, 回火时, mold in residual stress 松弛, for deformation has effect/influence. mold rear, surface 处于拉应 force 状态, rear dimensions will increase large;反之, surface pressure force 状态, generate shrinkage. 但组织转变 and force 松弛两项 effect/influence in, front is main/primary.