塑料模具设计技术英语

Chapter 1 General mould construction
1. 1 Basic Terminology
Impression: The injection mould is an assembly of parts containing within it an ‘impression’ into which plastic material is injected and cooled . It is the im- pression which gives the moulding its form. The impression may, therefore, be defined as that part of the mould which imparts shape to the moulding. ①The impression is formed by two mould members:
(I) The cavity, which is the female portion of the mould, gives the mould-
Ing its external form.
(II) The core, which is the male portion of the mould, forms the internal shape of the moulding.
Cavity and core plates: This is illustrated for a simple container in Figure
1.1. The basic mould in this case consists of two plates. Into one plate is sunk
the cavity which shapes the outside form of the
moulding and is therefore known as the cavity
plate. ②Similarly, the core which projects from
the core plate forms the inside shape of the
moulding. When the mould is closed, the two
plates come together forming a space between 图
the cavity and core which is the impression.
Sprue bush: During the injection process
plastic material is delivered to the nozzle of the
machine as a melt; it is then transferred to the
impression through a passage. ③In the simplest
case this passage is a tapered hole within a bush as shown in Figure 1. 2. The ma- terial in this passage is termed the sprue, and the bush is called a sprue bush.
Runner and gate systems: The material may be directly injected into the im- pression through the sprue bush (Figure 1. 2) or for moulds containing several impressions（multi-impression moulds) it may pass from the sprue bush hole through a runner and gate system ( Figure 1. 3 ) before entering the
Page 1 图图
impression. ④
Register ring:If the material is to pass without hindrance into the mould the nozzle and sprue must be correctly aligned. To ensure that this is so the mould must be central to the machine and this can be achieved by including a register ring (Figure 1.4).⑤
图
Guide pillars and bushes：To mould an even-walled article it is necessary to
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ensure that the cavity and core are kept in alignment. This is done by incorpora-
ting guide pillars on one mould plate which then enter corresponding guide bu-
shes in the other mould plate as the mould closes. ⑥An example with guide pil-
lars mounted on the core side and corresponding guide bushes in the cavity side is
shown in Figure 1. 4. The size of the guide pillars should be such that they main-
tain alignment irrespective of the applied moulding force; this they are normally
able to do. All the constituent parts of the basic mould have now been described
and a cross-section drawing of the assembled mould illustrated (Figure 1. 4).
Fixed half and moving half: It can be seen (Figure 1. 2) that the various
mould parts fall naturally into two sections or halves. Hence, that half attached
to the stationary platen of the machine (indicated by the chain dotted line) is
termed the fixed half.The other half of the mould attached to the moving palten
of the machine is known simply as the moving half. ⑦Now it has to be decided in
which of the two halves the cavity or core is to be situated. Generally the core is
situated in the moving half and the overriding reason why this is so, is as
follows:
The moulding, as it cools will shrink on to the core and remain with it as the
mould opens. This will occur irrespective of whether the core is in the fixed half
or the moving half. ⑧However，this shrinkage on to the core means that some
form of ejector system is almost certainly necessary. Motivation for this ejector
system is easily provided if the core is in the moving half. Moreover, in the case
of our single-impression basic mould, where a direct sprue feed to the underside
of the moulding is desired the cavity must be in the fixed half and the core in the
moving half (Figure 1. 2).
New Words and Expressions
impression 模腔integer 整体的
female 凹陷的sprue bush 主流道衬套，浇口套
inject 注射，注塑fixed half 定半模
core 型芯stationary platen 固定模板
shrinkage 收缩Multi-impression 一模多腔
runner 分流道guide pillar 导柱
feed 进浇moulding 塑件
Page 3
male 凸出的insert 镶块
cavity型腔register ring 定位环
bolster 支撑moving half 动半模
sprue 主流道single-impression 一模一腔
gate 浇口keep in alignment 对中，对齐
nozzle注塑机喷嘴guide bush 导套
Notes
①The injection mould is an assembly of parts containing within it an 'im-
pression' into which plastic material is injected and cooled. It is the impression
which gives the moulding its form. The impression may. therefore. be defined
as that part of the mould which imparts shape to the moulding. 注塑模是一些零
件的组合，其中包含了一个型腔。

塑料注人这个型腔并在里面冷却。

型腔决定了
塑件的形状。

因此，型腔可以定义为模具中，给塑件传递形状的那部分零件。

②Into one plate is sunk the cavity which shapes the outside form of the
moulding and is therefore known as the cavity plate.其中一块板加工出凹入的
型腔，成型塑件的外形.因此称作为型腔板。

③During the injection process plastic material is delivered to the nozzle of
the machine as a melt。

it is then transferred to the impression through a pas-
sage.在注塑过程中,塑料以熔融状态从注塑机的喷嘴射出.然后通过一条通道
传输进人型腔。

④The material may be directly injected into the impression through the
sprue bush(Figure 1. 2) or for moulds containing several impressions (multi-
impression moulds) it may pass from the sprue bush hole through a runner and
gate system (Figure 1. 3) before entering the impression.塑料可以如图1.2所
示通过主流道衬套直接注人型腔或在含有几个型腔的模具(多型腔模具)中穿过
主流道衬套孔之后通过一个流道和浇口系统进人型腔(图1-3).
⑤If the material is to pass without hindrance into the mould the nozzle
and sprue must be correctly aligned. To ensure that this is so the mould must be
central to the machine and this can be achieved by including a register ring
(Figure 1.4).如果希望塑料不受阻碍地进人型腔，喷嘴和主流道必须准确地对
中.要确保这一点，模具必须定位在模具的中心。

这是通过设置一个定位环来达
到的《图1.4)。

⑥To mould an even-walled article it is necessary to ensure that the cavity
Page 4
and core are kept in alignment. This is d0ne by incorporating guide pillars on
one mould plate which then enter corresponding guide bushes in the other mould
plate as the mould closes.要注塑一个均匀壁厚的塑件，必须确保型腔和型芯的
对中.这可以通过在一块模板上安装异柱，然后在合模时插入另一块模板上对应
的导套来实现。

⑦Hence，that half attached to the stationary platen of the machine (indi-
ated by the chain dotted line)is termed the fixed half. The other half of the
mould attached to the moving platen of the machine is known simply as the mov-
ing half.因此，安装在注塑机固定板上的那一半(由点划线表示)称为动半模。

安装在注塑机的动模板上的另一半简单地称为动半模。

⑧The moulding,as it cools will shrink on to the core and remain with it as
the mould opens. This will occur irrespective of whether the core is in the fixed
half or the moving half.塑件在冷却时将收缩在型芯上,模具打开时塑件就留
在了型芯上。

不管型芯在动半模还是在定半模都会发生这种情况。

1.2 Integer cavity and core plates
Let us consider the methods of incorporating cavity and core. We have now
seen that in general the core is incorporated in the moving half and the cavity in
the fixed half. However，there are various methods by which the cavity and core
can be incorporated in their respective halves of the mould.These represent two
basic alternatives ：（a）the integer method Where the cavity and core can be ma-
chined from steel plates which become part of the structural build-up of the
mould,or (b) the cavity and core can be machined from small blocks of steel ,
termed inserts ,and subsequently bolstered . ①The choice between these alterna-
tives constitutes an important decision on the part of the mould designer.The fi-
nal result .nevertheless,will be the same whichever method of manufacture is
chosen.In either design the plate or assembly which contains the core is termed
the core plate and the plate or assembly which contains the cavity is termed the
cavity plate.
When the cavity or core is machined from a large plate or block of steel, or is
cast in one piece, and used without bolstering as one of the mould plates, it is
termed an integer cavity plate or integer core plate. This design is preferred for
single-impression moulds because of the strength，smaller size and lower cost characteristics.②It is not uesd as much for multi-impression moulds as there are
other factors such as alignment which must be taken into consideration. Typical
Page 5 mould designs which incorporate an integer cavity and core are shown in
Figure 1.5.
图
Of the many manufacturing processes available for preparing moulds only
Two are normally used in this case. There are (a) a direct machining operation on
A rough steel forging or blank using the convenrional machine tools, or (b) the
‘precision’ investment casting technique in which a master pattern is made of the
Cavity and core.③The pattern is then used to prepare a casting of the cavity or
core by a special process. A 4-1/4% nickel-chrome-molybdenurn steel (BS 970-
835 M30) is normally specified for integer mould plates which are to be made by
the direct machining method. The precision investment casting method usually
Page 6 utilizes a high-chrome steel.
New Words and Expressions
cast 铸造incorporate 安装，装配blank 坯料
chrome 铬
core plate 型芯板master pattern 样模strength 强度forging 锻造
nickel 镍
molybdenum 钼
cavity plate 型腔板precision investment casting 精密熔模铸造
①(a) the integer method where the cavity and core be machined from
steel plates which become part of the structural build-up of the mould ,or (b)
the cavity and core can be machined form small blocks of steel .termed inserts,
and subsequently bolstered.（a）整体式，这是从构成模具结构件的钢模板上直
接加工出型芯和型腔；（b）型腔、型芯可以从小的钢块加工而成，称作镶块，然
后嵌入模板。

②When the cavity or core is machined from a large plate pr block of steel,
Or is cast in one piece , and used without bolstering as one of the mould plates, it
is termed an integer cavity plate or integer core plate. This design is preferred
for single-impression moulds because of the strength,smaller size and lower
cost characteristics.当型腔或型芯从一块大的板料或钢块，或铸造出的板上加
工，而不用边框时，就称为整体式型腔板或整体式型芯板。

这种设计因为强度
高、尺寸小和成本低，而适用于单一型腔的模具。

③These are (a) a direct machining operation on a rough steel forging or
blank using the conventional machine tools, or (b) the ‘precision’ investment
casting technique in which a master pattern is made of the cavity and core.方法
（a）在锻钢的粗坯上使用传统的机床直接加工；方法（b）采用精密熔模铸造技
术，要求先做一个型腔或型芯的样模。

1.3 Use of local inserts
These may be incorporated in the integer block in order to simplify the
Page7
process of mould making . If they are used, a reccss or hole is made in the cavity
or core plate to accommodate the insert which is then securcly fitted into posi-
tion. ①Some examples of the judicious use of local inserts in the integer type of
mould are given below.
Example l. The cavity form for a bucket which has a rim at the base to
stand on. ②In this case the narrow groove in the base of the cavity, necessary for
forming this rim, represents a
reasonably difficult machining
problem. This difficulty can be
overcome by making the base of
图the cavity in the form of a local in-
sert, as shown in Figure
1. 6. This method has the addi-
tional advantage that the cavity
can be formed by a straight-
through maching operation
which cuts down the overall ma-
chining time. The local insert is
machined separately and then sup- ported at the base by a subsidiary backing plate.③
Example 2. A local variation in an otherwise constant form is required in a moulding. The example chosen here is of a bath with carrying handles, one of
which is shown in Figure l. 7 (a). The inside form of the bath rim requires a complementary male form around the top of the cavity (b). Now, while most of
it can be produced by a simple turning operation, the presence of the handle pro-
jection prevents any simple machining operation if a wholly integer mould is at- tempted.The general form of the rim and the impression is shown at (c) and the
local section at the handle (d). Without a local insert all of the projecting male
form on the cavity side will have to be made by copy milling which is time-consu-
ming and costly.④However, by incorporating the local insert shown at (e) the
rim can be turned and a recess made for the insert by a simple milling opera-
tion. The local insert, incorporation the male form the landle is then fitted into
thc recess in the cavity plate. So far as the core side is concerned, it is not neces-
sary to use an insert. In this case the external mould form for the handle is made
by removing metal form the general form of the core plate and not, as in the pre-
Page 8
图
Figure l. 7 Illustrating desirability of fitting local insert into an integer cavity: (a)
part of component (a bath)-note projecting handle; (b) sketch of corresponding por-
tion of cavity-note projection to form handle; (c) cross-section through mould at
' X-X'; (d) cross-section through mould at 'Y-Y' without local insert; (e) cross- section through mould at ‘Y-Y' with local insert
vious case，by adding metal to it.
Example 3．A mould contains slender projections which may get damaged
and require replacement. Any small projection that forms a moulding recess or
hole and which is liable to damage because of its proportions relative to the rest of
the mould should be incorporated as a local insert. This will allow easy replace-
ment of the damaged part. An example is illustrated in Figure l. 8. This shows a
sketch and part section of a mould for a toothbrush stock. A hole is required in
the handle of the component. The core which forms this is a slender rectangular
图
Figure l. 8 Local insert forming hole in toothbrush stock
Page9
projection, and while this can be made by machining from the solid cavity plate it
is more practical to let in a local insert as shown in the section drawing. ⑤The
local insert is held in position by a threaded plug.
Example 4. A round hole is required in the moulding. The reasons for adopting a
local insert in this case will be similar to the last example if the size of the hole necessi- tates a slender core . However, in general, the reason for using local inserts is that the male form required to mould the hole is round and a round, local insert, core pin is very much simpler to produce than the corresponding pin machined from the solid. When round holes are specified in the component form, the mould designer should always consider the use of local inserts. These round pins fit into holes machined into the mould member (cavity or core plate).
The various methods of securing circular local inserts to a mould plate are Shown in Figure l. 9. Relatively large-diameter local inserts can be secured either
bya flange fitting (a) or by the screw-down method (c) . For small-diameter
local inserts the shoulder method is always adopted (b) . Note that the overall
lengths of the local inserts in the latter design have been shortened for ease of manufacture.⑥
图
Figure l. 9 Various methods for sccuring local inserts
Example 5．An engraving is to be included in the impression. This is
图
Figure l. 10 Engraved (local insert) pad fitted to integer cavity usually best incorporated as a local insert pad to allow for change of engraving if this is required. There
are other reasons however. First, if
the engraving were to be made at the bottom of a deep cavity, the engrav-
ing operation would be extremely difficult. Second, as engraving ma- chines are usually of light construc-
Page10
tion, they will not accommodate large mould plates. An engraved insert pad is shown in Figure 1.10. In this case the pad is incorporated in a pocket machined in the bottom of the cavity, and securred with socket-headed screws.⑦
New Words and Expressions
recess槽，凹陷
groove 凹槽
sketch草图
secure 固定
fitted into position 定位
back plate支承板
threaded plug 螺栓
screw-down 螺钉固定
engraved insert pad 嵌入式镶块垫块accommodate适应
projection 凸台，突出部分cross-section横截面
flange 法兰
local inserts 局部镶块
copy milling 仿形铣削
hold in position 固定
core pin小型芯，成型杆socket-headed screw 沉头螺钉
Notes
①If they are used，a recess or hole is made in the cavity or core plate to accommodate the insert which is then secureLy fitted into position.如果采用局部
镶块，必须在型芯或型腔板上开始凹槽或孔，以便适应镶块的安全定位。

②The cavity form for a bucket which has a rim at the base to stand on.桶
形塑件的成型型腔底部有一起支脚作用的凸边。

③This method has the additional advantage that the cavity can be formed
by a straight-through machining operation which cuts down the overall machi-
ning time. The local insert is machined separately and then supported at the base
by a subsidiary backing plate.这种方法的另一优点是型腔可以直接切削加工，
缩短整体加工时间。

局部镶块可以单独加工，然后应用辅助支承板支撑。

④The example chosen here is of a bath with carrying handles, one of
which is shown in Figure l.7（a）．The inside form of the bath rim requires a complementary male form around the top of the cavity (b). Now, while most
of it can be produced by a simple turning operation, the presence of the handle
projection prevents any simple machining operation if a wholly integer mould
is attempted. The general form of the rim and the impression is shown at (c)
and the local section at the handLe (d). Without a local insert all of the Project-
Page11
ing male form on the cavity side will have to be made by copy milling which is
time-consuming and costly．此例为含运输扶手的浴盆，见图1.7(a)。

浴盆边沿
的内形需要型腔顶部周边有一辅助凸台成型，见图(b)。

假设应用全部整体式模
腔，这个塑件的大部分区域均可以采用简单车削成型，而扶手凸台部位无法进行简
单切削加工。

边沿和型腔的通用形式如图(c)，扶手的局部剖面如图(d)。

如果不
采用局部镶块，型腔侧突出的凸台就必须采用价格昂贵又费时的仿形铣加工。

⑤The core which forms this is n slender rectangular projection, and while
this can be made by machining from the solid cavity plate it is more practical to
let in a local insert as shown in the section drawing.成型细长矩形凸台的型芯虽
然可以直接从型腔扳中加工，但是采用如截面图所示局部镶块更符合实际。

⑥Relatively large-diameter local inserts can be secured either by a flange
fitting (a) or by the screw-down method (c). For smalL-diameter local inserts
the shoulder method is always adopted (b). Note that the overall Lengths of the
local inserts in the latter design have been shortened for ease of manufacture.相
对直径较大的局部镶块既可以采用法兰固定[图(a)]，也可以采用螺钉固定连
接[图(c)]。

对于小直径局部镶块一般采用台肩固定[图(b)]。

后者设计中应
注意为便于加工，镶块的总长应尽量缩短。

⑦In this case the pad is incorporated in a pocket machined in the bottom of
the cavity，and secured with socket-headed screws.这里垫块安装在型腔底部的
槽内，采用沉头螺钉固定。

1. 4 Inserts for cavity and core
For moulds containing intricate impressions, and for multi-impression
moulds, it is not satisfactory to attempt to machine the cavity and core plates
from single blocks of steel as with integer moulds. The machining sequences and
opertation would be altogether too complicated and costly. The insert-bolster
assembly method is therefore used instead.
the method consists of steel are known, after machining, as inserts, and
the one which forms the male part is termed the core insert and, conversely, the
one which forms the female part the cavity insert. These are then inserted and se-
curely fitted into holes in a substantial block or plate of steel called a bol-
ster. These holes are either sunk part way or are machined right through the bol-
ster plate. In the latter case there will be a plate fastened behind the bolster and
this secures the insert in position①
Shape and type of insert: To simplify machining the designer should make
Page12 the insert either circular or
rectangular in shape, Which
of these two shapes is to be
used depends on the shape of
the mouldting. It is convenient
to make circular or near circu-
lar mounldings in correspond- 图
ingly shaped inserts and all
other shaped moulding in rec-
tangular inserts. Examples are
illustrated in Figure l. 11. Circular
inserts are fitted into holes in the
blster ( Figure l. 12). A bol-
ster for a multi-impression
mould will, therefore, have a
number of holes either in
lirws or on a pitch circle diam-
eter. ②The latter system is il- lustrated in Figure l. 13. An important economic aspect of a multi-impression mould containing circular inserts is Figure l. 11 Types of cavity and core inserts (a. b) rectangular, screw-down; (c, d) rectangular, flanged; (e, f) circular, screw-down;
(g, h) circular, flanged
that the manufacture of the inserts, the turning and the machining of the bolster
holes by boring are both cheap machining operations.
图
Figure l. 12 Fitting details for small core insert
Page13 图
Figure l. 13 Circular core inserts ( flanged)
fitted to frame-type bolster
As previously stated, for com- ponents with shapes other than cir- cular it is generally desirable to
make the insert rectangular.③The
reason for this is best explained by
an example. Consider the case of a
long narrow component, say a box .If
a circular insert is used, the diame-
ter of the insert will be related to
the length of the component, so
that the circular insert will be relatively large. If a multi-impression mould is re-
quired, the mould will also have to be large to accommodate these inserts. This
will offset the economic advantages gained by using circular inserts in the first
place. Rectangular inserts are fitted into a multi-impression mould in a different
manner to the circular inserts just mentioned. In general, they are placed together
to from one large insert (Figure l. 14). This illustrates the core plate of a six-
impression mould in which each core has been machined as a separate
insert. However, the rectangular inserts have been placed side by side in two sets
of three and between the two sets is inserted a central block of steel called a
bridge piece.④This central block is incorporated to allow one large pocket to be machined out of the bolster plate rather than two smaller pockets each to contain
three insersts only.⑤It may be felt that the bridge piece could be dispensed with
by making the inserts larger and meet, in fact, on the mould' s centre
line. However, this creates difficulties for both the sprue bush and the feed sys-
tem. Without the bridge piece the sprue bush would enter the mould on a line
图
Figure l. 14 Rectangular core inserts (screw-down) fitted to solid bolster
Page14
Where the edges of two inserts meet and the main runner would be along the line
Also. If there is a silght gap between the inserts the material will creep down and
Tend to force the inserts apart.
Although in many cases the, multi-impression mouId will have the same im- pression repeated scveral times, there are examples when it will contain a number
of differently shaped impressions. This happens quite frequently in the toy indus
try, where all the component parts of a toy are incorporated in the same
mould. One moulding shot then gives all the components necessary to complete,
the article.
The dimensions adopted for each insert will depend primarily on the size and
shape of the moulding. However, the individual insert dimensions are adjusted so
that the final, overall, form of the complete insert assembly is rectilinear. This
procedure facilitates the machining of the bolster and in fitting the inserts to the
bolster.
Local inserts can again be used in cavity and core inserts. Previously we saw
their use in integer cavities and cores, and their function here is similar.
Another variation in the make-up of a cavity or core insert is that either one or both can be made in more than one piece. An example (Figure l. 15) is of a component called a rocker arm (a). The slender wings on the component make the machining of a one-piece cavity insert difficult. By making the cavity insert in two parts (b) the machining is simplified. The outside form of the composite in- sert is made a convenient shape for bolstering purposes.
Methods of fitting inserts. There
are two methods by which inserts can
be securely fitted into a bolster. Which
method is used will depend on the
type of insert and the problem is out-
lined below.
Method (i) uses the screw-down technique. In this case the insert fits in- to a blind recess in the bolster and is secured by socket-headed screws
图
Figure l. 15 Composite rectangular cavity insert: (a) component (rocker arm) ;
(b) composite cavity insert
from the underside through holes bored in bolster. Note that the threaded
holes in the insert which receive the screws should not be drilled right through
the insert, because the resultant gap left above the end of the screw may well be-
Page15。