快速制模技術(shù)

·

逆向工程與快速成形技術(shù)·

Reverse

Engineering

andRapid

Prototype

Technology第9章

快速制模技術(shù)天津科技第1大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyRT

(Rapid

Tooling)快速制模RM

(Rapid

Molding)快速模具制造

CSM

(Cold

Spray

Mould)冷噴模

Hard

Tooling硬質(zhì)模Soft

Tooling軟質(zhì)模Bridge

Tooling過渡模

Epoxy

Mould環(huán)氧樹脂模

Rubber

Mould橡膠模

Injection

Mould注射成形模SRM

(Silicon

Rubber

Mould)硅膠模HSM

(Hot

Spray

Mould)熱噴模Unbaked

Ceramic

Molding無焙燒陶瓷型Room

Temperature

Vulcanizing

(RTV)

Molding室溫硫化模

Spray

Metal

Molding金屬噴涂模Resin

Transfer

Molding樹脂過渡模Vacuum

Form

Tooling真空成形制模

Epoxy

Tooling環(huán)氧樹脂制模天津科技第2大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyRTV室溫硫化橡膠模

1-20件EPOXY

Tooling鋁合金樹脂模

10-1000件3D

KEL

TOOLINGA6

tool

steel/stellite/copper

tungsten1000-1,000,000件天津科技第3大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyStellite鎢鉻鈷合金,硬合金天津科技第4大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyTOOLING

APPLICATIONS

WITH

EOSINT

MMike

Shellabear,

Joseph

WeilhammerEOS

GmbH，

2007天津科技第5大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

Technology1.

IntroductionEOSINT

M

systems

manufacture

solid

metal

parts

by

locally

melting

andresolidifying

metal

powder

using

a

focussed

laser

beam,

layer

by

layer,

tbuild

up

the

desired

geometry

fully

automatically

from

3D

CAD

data.

Theproduction

process

is

known

as

Direct

Metal

Laser-Sintering

(DMLS).Depending

on

the

powder

material

and

processing

parameters

used,

awide

range

of

part

properties

can

be

obtained,

from

controlled

porosity

fventing

or

filtering,

up

to

fully

dense

structures

with

strength

superioor

forged

components.Tooling

has

been

the

main

application

of

EOSINT

M

technology

for

at

leathe

first

decade

since

its

commercial

launch

in

1995.

This

application

isknown

as

DirectTool.

In

addition

to

the

“rapid”

aspect,

the

focus

has

smore

to

using

the

unique

geometric

possibilities

of

the

technology

to

des“advanced

tooling”,

for

example

by

integrating

conformal

cooling

channinto

tooling

to

improve

quality

and

economics

in

production.Today

EOSINT

M

tools

are

being

used

for

example

to

injection

mouldmillions

of

plastic

parts

and

to

die

cast

tens

of

thousands

of

metal

partsThis

white

paper

gives

an

overview

of

how

and

why

EOSINT

M

technologyis

used

in

tooling

applications,

focussing

in

particular

on

the

most

commapplication,

injection

moulding.天津科技第6大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyIn

this

case

the

requirement

was

for

series

production

of

twosmall

plastic

components

in

polycarbonate.

Although

fairly

simpleconventional

tooling

would

still

have

required

EDM

work.Using

an

EOSINT

M

270

system,

the

core

and

cavity

were

builtin

just

5

hours

40

minutes.

No

post-machining

was

required,

thefinishing

only

involved

shot-peening

and

slight

manual

touchingup.

The

core

and

cavity

were

mounted

directly

onto

the

injectionmoulding

machine,

and

production

was

started.Only

six

days

were

needed

from

project

start

to

seriesproduction.天津科技第7大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

Technology√a

joystick

assembly

for

a

construction

vehicle.施工車輛√5,000

assemblies

were

required,

each

comprising

14

injectionmoulded

parts.√all

14

injection

moulds

were

produced

and

the

5,000

sets

mouldedwithin

nine

weeks,

including

a

three

week

delay

due

to

designchanges

made

by

the

customer,

and

modification

of

one

tool

tocompensate

for

asymmetric

shrinkage

of

a

circular

plastic

part.√The

six

working

weeks

compared

to

16

weeks

as

the

fastestdelivery

time

quoted

by

suppliers

using

conventional

technology,√in

additional

the

tooling

cost

only

around

50

percent

of

the

nextbest

offer.天津科技第8大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyAdvanced

Tooling

for

improving

tool

performanceDirect

Metal

Laser-Sintering

(DMLS).With

DMLS,

both

the

positions

and

shapes

of

coolingchannels

(or

other

elements)

can

be

designed

in

a

freeform

way.天津科技第9大頁學(xué)/共T1i2an8j頁in

University

of

Science

&

TechnologyDMLS

is

often

combined

with

other

productionmethods

for

one

tool,

an

approach

which

is

oftencalled

hybrid

tooling.Direct

Metal

Laser-Sintering

(DMLS).天津科第技1大0頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyThe

cycle

time

was

reduced

from

15

seconds

to

just

8-9

seconds,

giving

aproductivity

improvement

of

approximately

75

percent,

with

no

loss

of

quality.Fig

7(b)

shows

a

cooling

core

designed

to

be

inserted

into

the

rear

of

the

ejecside

of

a

mould

to

remove

heat

from

the

injection

area.

This

reduced

the

cycle

tiin

production

by

two-thirds.7(c)

shows

a

core

with

integrated

conformal

cooling.

The

dome

includes

a

spirshaped

cooling

channel,

but

the

core

has

been

designed

so

that

the

lower

half

cabe

easily

machined.天津科第技1大1頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyThe

Rapid

Tooling

Alternative天津科第技1大2頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyAdditive

metalworking

technology

meets

rapid

prototyping

todeliver

production-quality

tooling.

The

approach

aims

to

createcomplex

molds

faster

and

cheaper

than

CNC

machining.By

Peter

ZelinskiEconomical

additive

processes

now

being

developed

aim

to

takemold

making

in

a

new

direction.

Or

more

specifically,

in

theopposite

direction—because

CNC

machining

is

at

its

essence

asubtractive

approach.

That

is,

material

is

removed.

By

contrast,an

additive

process

creates

a

solid

form

by

building

up

thematerial.

Shorter

leadtime

for

the

most

complex

metal

parts—particularly

mold

tooling—is

the

primary

benefit.At

least

one

company

has

come

to

market

with

a

reliableprocess

for

additive

mold

making.

3D

Systems,

the

Valencia,California,

maker

of

rapid

prototyping

equipment,

markets

apowder

metal

process

it

calls

"3D

Keltool."An

early

believer

was

Jim

Rogers,

president

of

Rogers

Tool

&Die,

an

injection

mold

shop

nearby

in

Valencia.

Mr.

Rogers

nowroutinely

uses

3D

Keltool

to

produce

molds

with

complex天津科第技1大3頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technologycontours,

narrow

slots

and

other

features

that

he

believes

CNCmachining

would

produce

more

slowly.

3D

Systems

converts

hisCAD

files

into

Stereolithography

(SL)

masters,

and

from

thereinto

the

final

mold

inserts

through

the

powder

metal

process.The

result

is

not

rapid

prototyping.

It"s

rapid

tooling.

That

is,production

tooling

in

tool

steel

composite,

offering

tool

life

thahas

run

to

ten

million

parts

for

neat

plastics,

and

to

one

millionparts

for

glass-filled

resins.

Surface

finish

is

20

to

25

microinchand

dimensional

accuracy

is

±0.001

inch

over

a

12-inch

length—achieved

without

making

a

single

NC

machining

move.

Theprocess

can

generate

not

only

molds,

but

also

copper-tungstenEDM

electrodes.

And

3D

Systems

promises

that

it

can

deliverproduction

tooling

like

this

within

ten

business

days

of

obtainingmaster

pattern.There

are

limitations.

One

is

that

any

3D

Keltool

rapid

tooling

must

bydefinition

be

delivered

by

3D

Systems.

The

process

is

proprietary.

It

ialso

reportedly

complex—so

there

is

no

realistic

way

to

duplicate

theprocess

within

a

mold

maker"s

shop.There

is

also

a

size

limit.

At

present,

rapid

tooling

inserts

from

thisprocess

can

have

an

area

no

larger

than

36

square

inches.And

while

another

company

is

working

on

an

SL-based

rapid

toolingapproach

it

hopes

will

overcome

both

of

these

limitations—that

is,

aprocess

for

oversize,

in-house

rapid

tooling—this

is

still

a

fledglintechnology

(see

sidebar).But

mold

maker

Jim

Rogers

says

a

series

of

mold

inserts

for

contouredtoy

components

illustrate

the

benefits

of

the

process

for

his

company.CNC

machining

would

have

demanded

a

leadtime

of

20

to

28

weeksfor

the

job,

he

estimates.

Rapid

tooling

let

him

deliver

the

same

job

tthe

customer

within

seven

weeks.

It

also

let

him

produce

the

tooling

ata

total

cost

about

15

percent

lower

than

what

machining

would

haverequired.天津科第技1大4頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyThe

3D

Keltool

process

is

an

additive

technique

that

skips

many

of

these

steps.It

requires

no

NC

machining,

and

therefore

no

tool

path

programming.

And

theprocess

produces

a

surface

requiring

less

polishing

than

a

comparablemachined

surface.

Often,

the

mold

requires

no

polishing

at

all.The

word

"Keltool"

refers

to

the

proprietary

powder

metal

sintering

process,which

involves

infiltrating

a

fused

metal

part

with

copper

alloy.

This

alloy

fthe

voids

in

the

otherwise

porous

material,

producing

a

surface

with

the

finis

and

hardness

necessary

for

an

injection

mold.Even

this

process

is

not

new.

It

was

introduced

in

1976

by

3M,

which

called

it"Tartan

Tool."

The

name

had

changed

to

Keltool

by

the

time

3D

Systemspurchased

the

process

last

year.Tartan

Tool

was

ahead

of

its

time.

Though

the

process

was

conceived

as

anapproach

to

toolmaking,

there

was

then

no

efficient

way

to

make

the

necessarypattern.

The

mold

maker

was

left

with

the

choice

of

either

machining

to

producethe

pattern

for

Tartan

Tool

or

machining

to

produce

the

mold

itself.

The

additiapproach

therefore

couldn"t

offer

a

productivity

advantage

for

most

jobs.Keltool

produces

rapid

tooling

where

Tartan

Tool

failed

to

do

so

for

a

simplereason:

The

options

for

efficient

pattern

making

have

grown

since

then.Stereolithography—building

a

solid

form

one

layer

at

a

time

by

laser-curing

aresin—can

now

produce

models

that

are

accurate

and

rigid

enough

to

stand

asrapid

tooling

patterns.

And

when

the

design

is

complex,

SL

can

deliver

thismodel

far

faster

than

CNC

machining.天津科第技1大5頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyThe

Process天津科第技1大6頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyExcept

for

a

shrink

factor,

the

3D

Keltool

process

precisely

returns

in

steelwhatever

was

provided

in

the

SL

master.This

master

can

be

either

a

positive

or

negative

model

of

the

injection

moldepart.

That

is,

the

master

can

resemble

the

part

itself

(positive)

or

the

toolinsert

(negative).The

correct

choice

is

the

one

that

lends

itself

to

hand

finishing.

A

smooth

suin

the

SL

master

carries

through

to

the

tooling,

and

the

clear

epoxy

SL

solidmuch

easier

to

polish

than

the

completed

steel

tool.

Therefore,

polishing

tibetter

spent

on

the

model

than

on

the

mold.

The

choice

of

positive

vs.

negativmodel

facilitates

this.

Critical

features

that

are

recessed

in

the

negativeof

the

model

stand

proud

in

the

positive

version,

and

vise

versa,

making

thesfeatures

easier

to

reach

for

polishing.The

intermediary

between

a

negative

master

and

the

negative

mold

is

a

roomtemperature

vulcanizing

(RTV)

silicone

rubber

"positive

in

a

box."

The

maste

placed

in

a

box,

and

the

rubber

poured

around

it.

Removing

the

master

leaves

acavity

in

the

shape

of

the

mold

insert.

Into

this

cavity

goes

the

proprietary

mix

that

is

fused

to

produce

the

final

tooling.The

ProcessA

positive

master

calls

for

an

additional

RTV

molding

to

achieve

the

same

endresult.

The

first

is

a

"negative

in

a

box,"

an

RTV

model

of

the

mold

insert

inplace

of

an

SL

one.

This

model

is

then

used

to

make

the

positive

RTV

moldingthat

holds

the

metal

mix.This

mix

can

be

chosen

to

output

either

of

two

types

of

steel.

One

is

an

A6composite,

produced

by

combining

standard

A6

with

a

dispersion

of

tungstencarbide

and

copper

alloy.

The

mix

improves

thermal

conductivity

over

A6

alonedecreasing

molding

cycle

times.

The

other

steel

composite,

Stellite,

offersproperties

similar

to

A6,

but

with

corrosion

resistance

similar

to

stainlessA

third

metal

choice

is

a

copper-tungsten

mixture.

This

is

used

to

make

rapidtooling

EDM

electrodes.Mold

makers

do

machine

these

metals,

but

only

to

add

sprue

holes,

guiding

pinholes,

runners,

and

other

secondary

features.

The

core

and

cavity—or

thefeatures

of

an

electrode—are

finished

and

complete.

According

to

3D

Systems,40

to

50

percent

of

its

customers

for

the

process

don"t

even

perform

additionapolishing

on

the

metal

surfaces.天津科第技1大7頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

TechnologyThe

housing

for

this

wireless

modem

was

molded

in

50

percentglass-filled

nylon

using

rapid

tooling.

Tool

life

for

3D

Keltool

moldshas

run

to

one

million

shots

for

glass-filled

resins

and

about

tenmillion

for

neat

plastics.天津科第技1大8頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology快速金屬原型制作技術(shù)

(Rapid

Casting

Technology)制作金屬零件一般需時7至10天，每次可生產(chǎn)數(shù)件至數(shù)十件。利用RCT技術(shù)有助加快產(chǎn)品開發(fā)過程，廠商在產(chǎn)品設(shè)計初期，便可利用樣件進(jìn)行工程檢定(散熱速度、性能、強(qiáng)度)、破壞性試驗

(destructive

test)、測試質(zhì)感等。天津科第技1大9頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology制作過程一.采用快速原型系統(tǒng)直接制作原型二.將蠟?zāi)Ｐ凸潭ㄓ诹⒅先?鑄造箱蓋著蠟?zāi)Ｐ退?在真空環(huán)境，混合石膏粉及水。將石膏漿注入鑄造箱，密封整個蠟?zāi)Ｐ臀?從真空混合器取出鑄造箱，將鑄造箱放于焗爐26~30小時，使石膏漿燒結(jié)，并熔化蠟?zāi)Ｐ?。燒結(jié)后石膏漿能抵受高溫六.從焗爐取出鑄造箱，將鑄造箱放于鑄造系統(tǒng)七.將所需分量的金屬放于熔爐八.PLC觸式控制器依參數(shù)指示進(jìn)行鑄造過程。將金屬熔掉只需數(shù)分鐘，視乎金屬的類型和分量。鑄造系統(tǒng)內(nèi)充滿氬氣，作用是防止金屬氧化九.開啟真空器皿，取出鑄造箱十.利用高壓水槍將石膏粉打碎，取得所需的金屬模型天津科第技2大0頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology只需要提供CAD立體模型，便可以通過激光快速原型(SLA)、熔融沉積法(FDM)或立體打印(Thermojet,Z-corp

3DPrinter及EOS

PS

Model)母樣代替蠟樣制成金屬模型。如用戶要求數(shù)件或至數(shù)十件首辦，便需要制造過渡模具如硅膠模等，作為生產(chǎn)蠟樣之用。天津科第技2大1頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology天津科第技2大2頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology天津科第技2大3頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology天津科第技2大4頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology天津科第技2大5頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology天津科第技2大6頁學(xué)/共Ti1a2n8j頁in

University

of

Science

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Technology具制造注射模具硅橡膠模樹脂型復(fù)合模沖壓模具消失模（二）

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Technology天津科第技3大2頁學(xué)/共Ti1a2n8j頁in

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Technology天津科第技3大4頁學(xué)/共Ti1a2n8j頁in

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Technology天津科第技3大5頁學(xué)/共Ti1a2n8j頁in

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Technology天津科第技3大6頁學(xué)/共Ti1a2n8j頁in

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Technology天津科第技4大1頁學(xué)/共Ti1a2n8j頁in

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Technology總結(jié)快速原型技術(shù)在模具制造中的作用典型快速原型技術(shù)的特點與直接應(yīng)用快速原型制造技術(shù)與快速模具制造之間的關(guān)系第42頁/共128頁·

原型－樣品－小樣－工業(yè)化前期－小批量－批量快速原型與物理模型·

實物模型對產(chǎn)品開發(fā)具有重要意義：1、設(shè)計理念的可視化 設(shè)計評價

2D－3D2、結(jié)構(gòu)驗證3、裝配校驗4、功能測試5、用戶直接、客觀評價、提出改進(jìn)意見6、產(chǎn)品評審、決策科學(xué)化第43頁/共128頁直接制模間接制模直接制模

Direct

Rapid

Tooling間接制模

Indirect

Rapid

Tooling直接制模應(yīng)用還很有限多數(shù)情況還需要經(jīng)過一次或二次轉(zhuǎn)換第44頁/共128頁SLA立體光刻工藝制模·

特點：1、成熟、自動化程度高?？梢灾圃焖芰夏＞撸m合小型模具制造2、模具表面粗糙度低（0.1mm左右）、精度高、結(jié)構(gòu)復(fù)雜3、模具容易翹曲、需要支撐結(jié)構(gòu)4、成型時間長、需要二次硬化（固化）5、運行成本高，材料有污染實例：杜邦公司 耐高溫光敏樹脂 塑料模具22件第45頁/共128頁SLS選擇性激光燒結(jié)制模材料種類多：樹脂、金屬粉末、陶瓷、混合二氧化碳激光器x-y

0.13mm

z

0.4mm間接方法：美國DMT

Rapid-Steel 鋼粉末（鎳鉻）＋表面包裹聚酯或后續(xù)滲金屬 已經(jīng)應(yīng)用到壓鑄模具、鍛壓模具

P197直接方法：德國EOS

DirectMetal鋼合金、鐵鎳合金、鈦鎳合金、鎳鋁合金等達(dá)到傳統(tǒng)金屬水平

p197第46頁/共128頁SLS制模特點制件強(qiáng)度高、無需設(shè)計支撐結(jié)構(gòu)可直接制作塑料、陶瓷、金屬制件材料利用率高適合中小型制件制作結(jié)構(gòu)疏松多孔、存在內(nèi)應(yīng)力、易變形陶瓷金屬件后續(xù)加工困難、尺寸精度低成型時間長第47頁/共128頁LOM工藝制模特殊紙質(zhì)，強(qiáng)度達(dá)到硬木水平、可機(jī)加工適合鑄造中的模芯、或小批量生產(chǎn)模型翹曲變形小、不需要設(shè)計與制作支撐具有較高的強(qiáng)度等良好的力學(xué)性能，耐溫達(dá)200度。適合制作大中型模具不適合制作薄壁件、材料利用率低后續(xù)加工費時費力，導(dǎo)致制模周期和成本提高最新進(jìn)展：金屬箔直接制作模具第48頁/共128頁FDM工藝制模熱熔噴頭、半流體材料、快速凝固成型材料是關(guān)鍵 石蠟、塑料、復(fù)合（樹脂或金屬）＋陶瓷等發(fā)展快、不需要激光制件強(qiáng)度較好、翹曲變形小適合中小型件需要設(shè)計支撐 （水溶性或酸溶性）成型時間長、材料特殊、價格貴表面紋絡(luò)明顯第49頁/共128頁4.1

快速模具的分類及基本工藝流程第50頁/共128頁基于快速原型的模具制造方法第51頁/共128頁基于RP原型一次轉(zhuǎn)換法制作樣件或模具的工藝流程第52頁/共128頁RP的快速模具制造

直接法和間接法基于RP的快速模具制造方法一般分為直接法和間接法兩大類。直接制模法是直接采用RP技術(shù)制作模具，在RP技術(shù)諸方法中能夠直接制作金屬模具的是選擇性激光燒結(jié)法(SLS法)。用這種方法制造的鋼銅合金注射模，壽命可達(dá)5萬件以上。但此法在燒結(jié)過程中材料發(fā)生較大收縮且不易控制，故難以快速得到高精度的模具。間接制模法生產(chǎn)出來的模具一般分為軟質(zhì)模具(SoftTooling)和硬質(zhì)模具(Hard

Tooling)兩大類。第53頁/共128頁軟質(zhì)模具軟質(zhì)模具因其所使用的軟質(zhì)材料(如硅橡膠、環(huán)氧樹脂等)有別于傳統(tǒng)的鋼質(zhì)材料而得名，目前提出的軟質(zhì)模具制造方法主要有硅橡膠澆注法、金屬噴涂法、樹脂澆注法等。軟質(zhì)模具生產(chǎn)制品的數(shù)量一般為50～5000件，對于上萬件乃至幾十萬件的產(chǎn)品，仍然需要傳統(tǒng)的鋼質(zhì)模具，硬質(zhì)模具指的就是鋼質(zhì)模具，利用RP原型制作鋼質(zhì)模具的主要方法有熔模鑄造法、陶瓷型精密鑄造法、電火花加工法等。第54頁/共128頁4.2軟質(zhì)模具快速制造方法與工藝第55頁/共128頁1、硅橡膠制造模具技術(shù)硅橡膠模具制造工藝是一種比較普及的快速模具制造方法。由于硅橡膠模具具有良好的柔性和彈性，能夠制作結(jié)構(gòu)復(fù)雜、花紋精細(xì)、無拔模斜度甚至具有倒拔模斜度以及具有深凹槽類的零件，制作周期短，制件質(zhì)量高，因而備受關(guān)注。第56頁/共128頁一種與石膏混合制作硅橡膠模具的工藝

硅橡膠材料的成本較高，占據(jù)著硅橡膠模具制作小批量樣件的大部分成本，尤其是尺寸較大單件

制品的制作。為此，人們一直在努力研究在該類

技術(shù)方法中如何能夠節(jié)省硅橡膠材料的用量，而

同樣也能夠制作出滿足要求的樣件來，下面介紹

一種通過與石膏混合制作硅橡膠模具的工藝方法。

該方法的工藝流程為：原型或樣件－分型處理－貼粘土或橡皮泥－配石膏漿－石膏造型－去粘土－澆注硅橡膠－修型－試制產(chǎn)品。第57頁/共128頁基于快速原型的模具制造方法·

1、平板

2、模框型

5、石膏3、粘土或橡皮泥

4、原6、型腔

7、8

硅橡膠第58頁/共128頁具體過程：(1)安放原型。對原型進(jìn)行必要的清理和處理后放置到平板上固定好，制作并固定?？颍乖椭車嗄？虻木嚯x均勻，在?？蚱桨鍍?nèi)表面上涂刷脫模劑（

a

和

b）。（2）貼粘土和澆石膏背襯。在原型表面貼粘土或橡皮泥（

b），然后將配好的石膏漿澆注到?？蛑?c)，待石膏漿固化后，再去掉粘土或橡皮泥層(d)粘在原型上的粘土或橡皮泥要清洗干凈，以免影響模具的表面質(zhì)量。第59頁/共128頁具體過程(3)硅橡膠澆注。根據(jù)去掉的粘土層的體積，計算所需調(diào)配的硅橡膠體積，再加上一定的損耗，進(jìn)行硅橡膠的調(diào)配。調(diào)配均勻后，在抽真空裝置中排除硅橡膠混合體中的氣泡。脫泡后進(jìn)行硅橡膠澆注（

e）。硅橡膠固化。將澆注好的硅橡膠模具在室溫下固化或加熱固化。待硅橡膠不粘手后，取出原型，繼續(xù)在室溫下或加熱使硅橡膠充分固化。修型。取出原型后，如果發(fā)現(xiàn)模具有少量缺損，可以用新調(diào)配的硅橡膠修補，并經(jīng)固化處理即可（

f）。第60頁/共128頁硅橡膠模具的特點硅橡膠具有良好的仿真性、強(qiáng)度和極低的收縮率。

用該材料制造彈性模具簡單易行，無需特殊的技術(shù)及設(shè)備，只需數(shù)小時在室溫即可制成。

硅橡膠模具能經(jīng)受重復(fù)使用和粗劣操作，能保持制件原型和批量生產(chǎn)產(chǎn)品的精密公差，并能直接加工出形狀復(fù)雜的零件，免去銑削和打磨加工等工序，而且脫模十分容易，大大縮短產(chǎn)品的試制周期，同時模具修改也很方便。

此外，由于硅橡膠模具具有很好的彈性，對凸凹部分澆注成型后也可直接取出，這是它的獨特之處。第61頁/共128頁模具硅橡膠材料的類型與特點

制模用硅橡膠為雙組分液體硅橡膠，分為縮合型和加成型兩類。

縮合型模具硅橡膠的主要組分包括：端基和部分側(cè)基為羥基的聚硅氧烷(生膠)、填料、交聯(lián)劑和硫化促進(jìn)劑。

加成型模具硅橡膠的主要組分包括：端基和部分側(cè)基為乙烯基的聚硅氧烷(生膠)、白炭黑(填料)、交聯(lián)劑、催化劑。第62頁/共128頁對比縮合型模具硅橡膠交聯(lián)過程中產(chǎn)生的乙醇等低分子物質(zhì)難于完全排出，致使模具在受熱時硅橡膠降解老化而顯著影響其使用壽命；同時由于乙醇等低分子物質(zhì)的排出致使硫化膠的體積收縮，從而造成模具的尺寸小于相應(yīng)的原型尺寸。因此，縮合型模具硅橡膠人多用作塑料與人造革生產(chǎn)中的壓花模具或用于一些尺寸要求不精密的工藝品制造。加成型模具硅橡膠在硫化時不產(chǎn)生低分子化合物，具有極低的線收縮率，膠料可以深度固化，而且物理性能、力學(xué)性能和耐熱老化性能優(yōu)異，成為了模具膠中正在大力發(fā)展的品種。加成型模具硅橡膠適用于制造精密模具和鑄造模具，而且模具制造工藝簡單，不損傷原型，仿真性好。第63頁/共128頁特點·

硅橡膠的這些優(yōu)點使它成為制模材料的佼佼者，一部分已進(jìn)入機(jī)械制造領(lǐng)域并與金屬模具相競爭。第64頁/共128頁

目前用硅橡膠制造的彈性模具已用于代替金屬模具生產(chǎn)蠟?zāi)?、石膏模、陶瓷模、塑料件，乃至低熔點合金如鉛、鋅以及鋁合金零件，并在輕工、塑料、食品和仿古青銅器等行業(yè)的應(yīng)用不斷擴(kuò)大，對產(chǎn)品的更新?lián)Q代起到不可估量的作用。

利用硅橡膠制造模具，可以更好的發(fā)揮RP＆M技術(shù)的優(yōu)勢。硅橡膠制造模具技術(shù)

隨著機(jī)械制造業(yè)的迅速發(fā)展，對模具的需求越來越大。一種較復(fù)雜的模具往往需要多塊組合而成，不但費用高，周期長，而且不易保證尺寸精度。

硅橡膠模具的產(chǎn)生，完全解決了這一難題。硅橡膠模具制造工藝是一種比較普及的快速模具制造方法

由于硅橡膠模具具有良好的柔性和彈性，能夠制作結(jié)構(gòu)復(fù)雜、花紋精細(xì)、無拔模斜度甚至具有倒拔模斜度以及具有深凹槽類的零件，制作周期短，制件質(zhì)量高，因而備受關(guān)注。第65頁/共128頁硅橡膠模具使用清理硅膠模，預(yù)熱模具。為了保證注型件充填完全，需要在上模中離澆口較遠(yuǎn)處和型腔較高處設(shè)置一系列的排氣孔。在進(jìn)行樹脂件澆注之前應(yīng)進(jìn)行必要的清理工作，例如清除溝槽內(nèi)的殘留物，檢查排氣孔是否堵塞等。清理工作完成以后，將硅膠模具放入溫箱中進(jìn)行預(yù)熱。噴灑離型劑，組合硅膠模具。為了便于注型件從模具中取出，需要在模具型腔表面噴灑離型劑，特別要注意噴灑深溝槽、深孔等難以脫模處。噴灑完離型劑后，就可以將硅膠模組合起來。第66頁/共128頁硅橡膠模具使用（續(xù)）計量樹脂。根據(jù)原型的重量進(jìn)行估算并根據(jù)澆注過程中材料的盈余進(jìn)行調(diào)整。初次澆注時，一般由原型的重量乘上一定的系數(shù)來初定所需澆注樹脂的重量。脫泡混合，真空注型。為了提高注件的致密程度和充填能力，需要將注塑環(huán)境抽真空，一方面除去樹脂和硬化劑中溶解的空氣，另一方面也抽去模具型腔中的空氣。抽真空的時間根據(jù)注型件的大小和具體情況有所不同，以是否達(dá)到真空度為準(zhǔn)。抽完真空后，將樹脂和硬化劑混合攪拌，然后澆注到模具型腔中。第67頁/共128頁硅橡膠模具使用（續(xù)）

(5)溫室硬化，取出制件。將澆注完的模具從真空機(jī)中取出，放入恒溫箱中進(jìn)行硬化，硬化時間根據(jù)件的大小和樹脂類型的不同而不同。待樹脂制品在指定的溫度和時間條件下完成固化后，便可以將制品開模取出。

(6)硅橡膠模具后處理。工件制好以后，還需要進(jìn)行必要的后處理工作才能交付使用，如除去澆道、打磨、拋光、噴漆等。第68頁/共128頁硅橡膠模具的應(yīng)用

對于批量不大的注塑件生產(chǎn)，可以采用RP原型快速翻制的硅橡膠模具，通過樹脂材料的真空注型來實現(xiàn)，這樣，能夠顯著縮短產(chǎn)品的制造時間，降低成本，提高效率。

對于沒有細(xì)筋、小孔的一般零件，采用硅橡膠模具澆注樹脂可制作制品達(dá)到50件以上。第69頁/共128頁2、基于RP原型的電弧噴涂制模工藝流程第70頁/共128頁2、電弧噴涂快速制造模具技術(shù)

電弧噴涂制模的思想起源于20世紀(jì)60年代提出的凈形熱噴涂成型(Net-shape

thermal

sprayforming)，基本過程是將熔化的金屬霧化，高速噴射沉積于基體上，所獲制件的形狀與基體相對應(yīng)，是一種集材料制備與成形于一體的制造方法。

電弧噴涂制造模具的最初構(gòu)想就是在塑料制品原型或木材、蠟、石膏等模型上噴涂一定厚度的金屬涂層，然后把涂層從基體上取下來，這就得到了可以復(fù)制原模型的模具型腔。電弧噴涂制模技術(shù)很早就被提出，在實際中并沒有得到應(yīng)用，這是因為此技術(shù)中存在很多技術(shù)難點。第71頁/共128頁電弧噴涂快速制造模具技術(shù)（續(xù)）

20世紀(jì)80年代后期，現(xiàn)代工業(yè)，塑料工業(yè)迅速地發(fā)展，尤其在汽車工業(yè)領(lǐng)域。

汽車更新?lián)Q代，都要求有與之配套的模具來制造，塑料產(chǎn)品的多樣化和小批量的特性決定了模具的

多樣性，這就意味著整個市場要求一種成本低、

周期短的制模方法。

傳統(tǒng)用機(jī)械加工和鑄造的方法來制造模具，其成本高，并且一旦產(chǎn)品改進(jìn)，就要求更換模具。

在制模領(lǐng)域，一種低成本、短周期的制模方法---電弧噴涂制模技術(shù)應(yīng)運而生，尤其是快速成型技術(shù)的出現(xiàn)和發(fā)展，可以快速高精度地制作復(fù)雜模型。第72頁/共128頁技術(shù)原理

電弧噴涂制模技術(shù)是將兩根帶電的金屬絲在噴槍前端相交形成電弧，金屬絲熔化，在壓縮空氣的作用下，將熔化的金屬霧化成金屬微粒，并以一定的速度噴射到樣模表面，一層一層地相互疊加堆積而形成高密度、高結(jié)合強(qiáng)度的金屬噴涂層，即模具型腔的殼體(或?qū)嶓w)。

這層殼體的內(nèi)壁形狀與樣模表面完全吻合，從而形成了所需的模具型腔。噴涂形成的金屬殼體與其他基體材料填充加固，結(jié)合成整體，再配以其他部件，即組成一付完整的模具。

制模工藝簡單，容易掌握，模具制作周期短，費用低，對比制作同一形狀尺寸的鋼模，制模周期和模具費用均可降低60％以上。第73頁/共128頁天津科第技7大4頁學(xué)/共Ti1a2n8j頁in

University

of

Science

&

Technology應(yīng)用·

電弧噴涂制?？蓮V泛用于塑料加工中的反應(yīng)注塑成型、吹塑成型、結(jié)構(gòu)發(fā)泡以及其他一些注塑成型等工藝中。

此方法制造的模具特別適于生產(chǎn)反應(yīng)注塑成型工藝中的聚氨酯零部件的生產(chǎn)，如汽車制造中可以用來生產(chǎn)駕駛盤、汽車儀表盤、座墊、頭部靠墊、阻流板、汽車內(nèi)飾頂蓬等：

在民用建筑方面可用來生產(chǎn)成型家具、隔熱材料；在輕工業(yè)中可以用來制造聚氨酯鞋底等。第75頁/共128頁電弧噴涂制模技術(shù)優(yōu)點因噴涂時原模的表面溫度一般不超過60℃，沒有熱應(yīng)力和變形問題。不論原模的材料是金屬、木材、或塑料制品，所得到的模具型腔線條輪廓

清晰，外形尺寸不變。制模效率高，尺寸不受限制，可小至硬幣的尺寸，大至制造汽車內(nèi)頂蓬真空成型模具。設(shè)備投資小，經(jīng)濟(jì)效益好。使塑料生產(chǎn)線能迅速更改產(chǎn)品的品種，符合市場的變化要求。成本優(yōu)勢就越顯著。同其他方法相比，此方法成本可節(jié)省2～20倍。第76頁/共128頁電弧噴涂制模的工序：模型準(zhǔn)備(清理模型表面、刷脫模劑)。模型可

由許多材料制成，包括木材、塑料、石膏、橡膠

等。模型準(zhǔn)備中最重要的是涂抹脫模劑。脫模劑在制模中的作用有兩個：首先，它對噴涂到基體

上的金屬顆粒有粘結(jié)作用，否則金屬顆粒將不能

牢固地吸附在模具表面而易脫落；其次，防止金

屬涂層對模型的過熱燒損、變形、粘附，起到隔熱、脫模的作用。將脫模劑均勻地涂在模型表面，并使其干燥成膜。在模型上噴涂金屬。待脫模劑干燥以后，在最佳的噴涂參數(shù)情況下，可以開始在模型上噴涂金屬，噴涂時應(yīng)保證使噴槍連續(xù)運動，防止涂層過熱變形，涂層厚度一般可控制在2～3

mm。第77頁/共128頁電弧噴涂制模的工序：(3)制作模具框架。如果模具在工作中要受到內(nèi)壓力或模具必須安裝在成型機(jī)上工作，模具必須有骨架結(jié)構(gòu)且制成的骨架應(yīng)帶有填料。模具框架制作應(yīng)注意兩個問題：

第一，使模具框架材料與涂層材料以及填料的熱膨脹性能相匹配；

第二，框架的外形尺寸及注射口的選擇要根據(jù)具體的注塑機(jī)型號而定。第78頁/共128頁電弧噴涂制模的工序：(4)澆注模具的填充材料。選擇澆注填充材料時，應(yīng)使填充材料具有較高的熱導(dǎo)率和較低的凝固收縮率同時模具在一定的溫度和壓力下工作，所以要求填充材料應(yīng)具有較高抗壓強(qiáng)度和耐磨性能。

一般選擇的填充材料為環(huán)氧樹脂與鋁粉等金屬粉末的混合物。

環(huán)氧樹脂使?jié)沧⒉牧吓c噴涂殼體、模具框架有很高的結(jié)合強(qiáng)度，有色金屬粉末可以提高模具的導(dǎo)熱性能，為提高模具的抗磨損性能可在填料中加入鐵粉

另外在澆注填充材料時可安放冷卻管，加強(qiáng)模具的散熱性能。第79頁/共128頁電弧噴涂制模的工序：(5)脫模、加工處理。如果在模型準(zhǔn)備階段做得比較合適，脫模不會很困難。脫模后要把殘留在金屬涂層表面的脫模劑清洗干凈。然后再根據(jù)不同的需要，可以對模具進(jìn)行拋光等后期制作。

在噴涂時，根據(jù)經(jīng)驗，模型尖角處涂層易開裂，所以模型應(yīng)避免尖角。對于大平面的噴涂，應(yīng)安裝工藝筋或加工工藝槽，可有效地防止涂層的起皮、鼓泡等現(xiàn)象。

根據(jù)電弧噴涂制模特點，將模框和模型以及模型的分型面固定在一起，經(jīng)噴涂Zn-A1-Cu合金，澆注背襯材料，使金屬殼、背襯材料與模框形成一體。第80頁/共128頁電弧噴涂專用表面處理劑PVA

西安交通大學(xué)研制的電弧噴涂專用表面處理劑PVA能很好地解決金屬扁平粒子的飛濺以及涂層的初期失穩(wěn)問題。同時，PVA能很好地溶化于熱水中，是一種良好的脫模劑。對于石膏材料模型，表面可直接噴涂PVA。

對于金屬、樹脂、塑料等材料，在噴涂PVA之前需在表面先噴涂一層細(xì)密的界面活性劑，減小界面張力差異，提高脫模劑與基體的浸潤性，以防PVA噴涂時出現(xiàn)表面聚集起球現(xiàn)象。

選用顆粒非常細(xì)的陶瓷粉(顆粒直徑小于5微米)