CA LC U L AT I O N S · D ES I G N · A PPL I CAT I O N S B . 3 . 3
Plastic parts with integrally molded threads
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Contents
1.
2.
Introduction
3
Requirements for joints with integrally molded threads Fixed joints 2.1 Movable joints 2.2
6.
Design
13
notes
13
6.1
Self-locking
6.2
Stress concentration in the
3
threaded section
3
6.2.1 Notch factors K
thread
3
zone
14
in
disengaged 14
I
6.2.2 Stress distribution within the internal 3.
Types of thread and key dimensions Fixed joints 3.1 Movable joints 3.2
engaged with (zone II, fig. 10)
thread
4 4
runout
sealing of plastic components integrally molded threads
15
Static
with
15
Design calculations for threaded joints Fixed joints 4.1
6
4.1.1 Stress in the vulnerable cross-section
6
4.1.2 Flank pressure p 4.1.3 Deformation of the threaded section
7
with
integrally molded
8
7.1
External thread
17
9
7.2
Internal thread
17
4.2
5.
14
6.2.3 Stress concentration in the thread
6
6.3 4.
the external thread
Movable
Calculation 5.1
joints
examples
10
Hose
connector
8.
10
Vehicle
jack
Injection molding of components
with threaded
made from POM
on
8.3
11
8.4
nut
Hostacom polypropylene (PP)
Hostalen PP Polypropylene (PP) Celanex Polybutylene terephthalate (PBT)
=
registered
trademark
19
separator 19
for
hopper Fastening nut for
corn
mill
spare wheel
Explanation of symbols
10. Literature
Reinforced
19
diesel vehicles
Grain
17
20 20
12 9.
Hostaform Acetal copolymer (POM)
threads
Examples of applications Water filter housing 8.1 8.2 Drainage plug for water
made from
Hostalen PPN 1060 5.3
7.
Reversible-flow filter made from
Hostaform C 2521 5.2
6
21
22
Introduction
1.
The
unique
freedom of
design
2.
afforded
Requirements for joints with integrally molded threads
by injection mold
enables this process to be used for the production of components with integrally molded threads. The addition
ing al
complexity and cost involved in terms of the injection (for demolding the thread) is relatively small.
2.1
Fixed joints
mold
The function of the above-mentioned
Integrally molded
threads
are
used for detachable fixed
joints in many different components. Examples include housing parts for washing machines and dishwashers, filters, valves and submersible and circulating pumps; fittings and screwed pipe joints; locking rings, e.g. on water meters and mincers; closures for packaging such as tubes, bottles and drums.
Integrally
molded threads
are
also used for movable
housing parts is safely apart from each other. For this purpose, the joint must be fixed and leaktight and should be suitably designed to prevent it loosening by itself. Leaktightness is achieved by integral sealing elements or additional sealing elements such as O-rings. In filter housings, e.g. for the fluff filter on washing machines, the joint should be quick and easy to undo in order to clean or change filters. generally
to
keep
different materials
joints
to convert rotary motion into linear motion or torque into linear forces and vice versa. Examples include valve stems,
telescopic spindles for ventilation windows, spindle nuts on car jacks, electric rear view mirror and seat adjusting systems and central locking in motor vehicles, reversing spindles in vending machines etc.
2.2
Movable joints
Movable threaded
joints, also known as helical gears, permit smooth, jolt-free transmission of motion. These threads are designed as single- and multi-start. should
Single-start threads are generally self-locking with low efficiency. The product of flank pressure p and speed v may
not
exceed certain limit values
ceptable heating
to ensure
up of the thread flanks does
Good low-friction and
wear
properties
are
that
unac
not occur.
exhibited
produced, for example, from the modified Hostaform grades C 9021 TF, C 9021 K, C 9021 G
by
threads
and
C 9021 M.
Once-only lubrication of the thread improves the slip properties of the mating thread and should always be carried out if possible.
3.
Table 1:
Types of thread and
Comparison
of
thread dimensions
important
key dimensions
Half
Thread
angle
of thread Thread type
depth
DIN
ß []
3.1
Fixed joints Metric 13
Threaded
can have very large thread comparatively low housing wall thickness typical of injection molded parts. This results in low inherent housing rigidity, so that the inner part can be compressed under radial force Fr and the outer part expanded. There is a risk that the thread flights will slide over each other and the joint will therefore fail. This
joints
in
housings
diameters in relation
to
ISO thread
Metric 513
The radial force Fr is proportional half angle of thread ß. =
FI
large thread depth reduces production tolerances. Fig.
1: Force
tan
the
to
the tangent of the
3
buttress thread
=
0.613 P
H!
=
0.541 P
h3
=
0.868 P
H!
=
0.75
103
trapezoidal
P
h3 =0.5P + a
Metric ISO 15
thread
H,
=
0.5 P
H!
=
0.640 P
Whitworth 228
pipe
27.5
thread
Threads
A
h3
the
risk is reduced the lower the radial force Fr and the greater the thread depth HI of the thread profile, fig. 1.
Fr
30
used for
preferably plastic
6063
containers
ß
(1)
sensitivity of the joint
10
c
=
0.5P
trapezoidal
10
c
=
0.5P
15
H4=0.50P
part 1 thread part 2
Round thread
405
to
(P
relationships on the thread flank
buttress thread
thread
=
pitch)
Metric ISO threads and Whitworth
large large
half thread
angles /?,
pipe
which lead
threads have
comparatively trapezoidal thread and the buttress and trapezoidal threads developed for plastic containers are more favorable, fig. 2.
Fig.
radial force Fr. The metric ISO
2: Thread types; illustration and
Fig.
F, FI F .3,
2 a: Metric ISO thread
Radial force Linear force
Perpendicular force Half angle of thread HI Thread depth
TÏ 1.
Table 1 compares the half angle of thread depth H! of different thread types.
ß
and thread
to
Q
Q
-
Q
thread %%2 ///Y//////////t P
explanation
(DIN 13)
of
terms
b: Metric buttress thread
2e: Thread
Fig.
(DIN 513)
preferably
to
tainers, buttress thread (DIN
be used for 6063 part
Outside diameter D; d DI; d| Root diameter
plastic
con
1)
c
Profile
z
Profile width
depth;
c
=
P Pitch
Fig.
2c: Metric ISO
trapezoidal
thread
2 f:
preferably to be used for plastics containers, trapezoidal thread (DIN 6063 part 2)
Fig.
(DIN 103)
Thread
U-P-
D; d
Outside diameter
DI; dj
Root diameter
c
Thread
z
Profile width
P Pitch
Fig.
-
2d: Whitworth
-5 W//Ï.
pipe
thread
Fig. 2g:
(DIN/ISO 228)
% Male thread ///////s////////////////.
Q
Q
O
o
-a
-o
Round thread
(DIN 405)
depth;
c
=
The lowest, practically negligible radial force Fr occurred with the metric buttress thread, fig. 2b, with a half angle of thread a
ß
3
=
thread
large
(tan
3
depth HI
=
=
Design calculations for threaded joints
4.
0.0524). This thread also has thread pitch). 0.75 P (P =
specified in DIN 405, fig. 2 g has a angle of thread ß 15 and the thread
The round thread
favorable half
=
0.5
Fixed joints
4.1
P is also in the range of other thread
depth H4 profiles. As a result of the special profile design, however, the flank overlap H5 is only 0.0835 P so that locally high surface pressure loadings are the result. =
In
designing
meters must
stress
High
radial forces with the risk of
impermissible
(DIN 2999). This thread type plastic components.
is therefore
be taken into
oz in
stress
para
account:
the vulnerable cross-section A^
2
un
suitable for
4.1 .1
Fig. 3.2
joints, the following
surface pressure loading p on the thread flanks change in flank diameters Zld2 and 4D2.
stresses
and deformation may be expected with Whitworth pipe threads with cylindrical internal and conical external threads
threaded
Stress in the vulnerable cross-section
3: Vulnerable cross-section AI and A2
Movable joints
joints, the metric ISO trapezoidal (DIN 103) proved successful. In rare cases, standardized flat profile (half angle of thread ß
For movable
has
thread a non=
0) is
used.
From the linear force F] stress
the
(fig. 1),
following
tensile
results:
"1
QZ
[N/mm2]
(2)
=
(d32
(3)
|
(Da2-D2)
=
A,, 2 where
It
A,
-
A2
=
-
d;2)
inside diameter [mm] outside diameter [mm]
D
nominal diameter
According
to
(4)
diameter [mm]
d3 d; Da
root
ist.
[mm]
DIN 13, part 21, the
(more exact)
stress
cross-section AS n
AS="
is
( d2
+
d3 Y
~
4\
calculated, which takes into
cut over
account
half the circumference
as a
the thread tooth
loadbearing
surface.
While this is
justified
in the
with metal
screws
with
of
high
the
material
root case utilization, plastic threads, ds is used to determine the loadbearing cross-section.
The linear force FI is composed of and operating force FB.
diameter
prestressing
The tensile
FI
=
FV
FI
FV
+
force Fy
FB
FB
calculated with linear force
(8)
perm.
values for
gives guide
long-term permissible (safety factor
function of temperature been taken into account).
stresses as a
already
The on
operating force may be an external force acting the joint or be produced by, for example, internal
Table 3 : Permissible tensile
pressure p;.
The
a
prestressing force Fv results from M according to the equation
the
0perm. in N/mm2
stresses
as
function of temperature
tightening
Temperature [C] Material
moment
60
20
80
100
120
2M
FV
P
+d2-fc
n
M
[N]
=
cos
+
ß
P
tightening thread pitch [mm]
fe
thread friction coefficient
fA
friction coefficient of the
d2 dA
flank diameter [mm] mean diameter of the
moment
half
(6)
dA fA
[N mm]
contact
surface
surface [mm]
contact
(fig.6)
angle of thread
Hostaform C 9021
10
6
3
Hostaform C 9021 GV 1/30
40
20
15
_
Hostalen PPN 1060
6
3
2
Hostacom M2 N02
8
4
2
Hostacom M4 N01
10
5
3
Hostacom G2 N02
12
9
6
4
Hostacom G3 N01
15
10
7
5
8
5
2
Celanex 2500
_
10
-
_
-
-
-
-
-
-
_
_
Celanex 2300 GV 1/20
20
16
14
12
10
Celanex 2300 GV 1/30
25
20
18
15
12
The friction coefficients
fG and fA depend on a number of influencing factors such as the particular combination of mating materials, surface roughness, sliding speed and the presence or absence of lubricant. Guide values in table 2.
are
shown
Table 2: Guide values for the friction coefficients fc and fA of unlubricated and lubricated surfaces
Friction
coe
ficient fG, fA
Material combination
dry PCR/PCR
(same)
0.3
PCR/PCR
(different)
0.15-0.25 0.1
PCR/AP
AP
4 .1.2
permissible
Flank pressure p
Although the linear force FI is not uniformly distributed over the intermeshing thread flights (see section 6.2.2), this is assumed for the purpose of calculating the flank
F,
-0.3
resulting operating pressure p;, the following applies:
than the
cross-section AI or A must be the outside diameter Da and/or
pressure p. Thus:
-0.4
P
from the internal
[N/mm2]
=
z
partially crystalline plastics amorphous plastics force FB
GZ is greater
loadbearing enlarged by increasing reducing the inside diameter d;.
0.15-0.25
For the
stress
stress, the
0.04-0.1
PCR/metal
PCR
lubricated
If the calculated
jt
d2
F}
linear force
d2
flank diameter
HI
thread
z
number of loadbearing thread
[N],
(9)
H! see
section 4.1.1
depth [mm] flights
L z
FB pi
dp
=
P,
J
dp2 [N]
(7)
internal pressure [N/mm2] diameter of the pressure-stressed surface [mm]
L
P
thread reach [mm] thread pitch [mm]
(10)
Guide values for in table 4
quoted
resulting from the half angle of thread ß (see fig. equation 1) leads to expansion of the outer part and compression of the inner part. This causes the flank overlap to be reduced. To calculate this deformation,
permissible flank pressure pperm. are (safety factor S is already taken into
The radial force Fr 1 and
account). Table 4: Guide values for in N/mm2
permissible
flank pressure pperm.
function of temperature
as a
it is assumed that the radial force Fr is distributed uni
formly
over
C
Temperature [C]
=
the thread
JT-d2-L
overlap
area
C:
^-d2-z-P [mm2]
=
(11)
Material 20
Hostaform C 9021 Hostaform C 9021 GV 1/30
60
80
20-25
15
12
45
35
30
100
120
_
6
4
2.5
flank diameter [mm], thread reach
z
number of
P
thread
da
see
fig.
2
_
20
Hostalen PPN 1060
L -
1
loadbearing thread flights pitch [mm]
_
Hostacom M2 N02
10
4
2.5
1
Hostacom M4 N01
12
5
3
2
Hostacom G2 N02
15
7
6
5
3.5
Hostacom G3 N01
18
9
8
6
4.5
Celanex 2500
20
7
3
2
-
Celanex 2300 GV 3/30
30
16
10
8
Celanex 2300 GV 1/20
40
32
24
20
15
Celanex 2300 GV 1/30
45
38
32
25
20
-
-
This
pressure pD, which is
gives
comparable
with the
internal pressure
[N/mm2]
=
PD
d,
TC
(12)
L
-
With wall thicknesses
and
si
s2
of the tubular segments
Da-D 1
=
S2
=
If the calculated flank pressure p is greater than the per missible, the thread reach L must be increased.
4.1.3
Deformation of the
threaded section
d3-dj
which
diameters Dm and It is necessary
to
check radial deformation of the
e can
(13)
[mm]
(14)
small in
generally
are
[mm]
dm, the
be calculated
by
mean
and the deformation
stress a
the
with the
comparison
following
formula:
threaded section if -
the thread has ISO
-
a
a
large
half
angle
of thread
ß (metric
ffi
fine
pitch
is chosen which results in
a
low thread
PD'
a2
continuous loads have
to
temperatures.
Fig.
4:
Explanatory diagram
at
m
=
d3 be transmitted
[N/mm2] for
the
part
(15)
inner part
(16)
outer
JL*
jLXg
depth HI -
y_ J
=
thread, Whithworth pipe thread)
dj
-
[N/mm2] for the
elevated
compression
Hence
of the
mean
diameter
on
the
outer
part is
PD-Pm Et(Da-D)
"
and
on
(17)
the inner part
pD-dm E2 (d3 di)
(18)
-
1,2
flexural creep modulus
Expansion
of the
JDm
=
8l
mean
-
Dm
[N/mm2],
diameter
=
on
the
see
table 5
outer
[mm] /^r^r (L>a L>) LI
-
part is
(19)
On the inner part, it is
The decrease in the flank 20
Adm
=
dra
e2
Pp-dn [mm] E2 (d3 d;)
=
(20)
JHi
-
The deformation of
overlap /iHi
should
not
exceed
30 % of the initial value.
to
S
(0.2
to
0.3) Hi
(24)
a plastic component is not only timetemperature-dependent but is also a function of stress level. Strictly speaking, separate characteristic
In the conversion of rotary into linear motion and vice
values should be determined for each type of stress. However for deformation ^ 2%, the variation between
with helical gears, the friction PR and resultant tem perature increase on the thread flanks is a crucial deter
the characteristic values is
mining factor in transmittable power. applies for the frictional energy:
Movable joints
4.2
and
the deformation of
negligible
so
that, for example,
component under compressive be calculated with sufficient accuracy using may
stress
a
versa
the flexural creep modulus.
PR
therefore, the flexural value, table 5.
For E
creep modulus is used
as
the
fc
characteristic
(DIN
54
fG-Fi-v[W]
=
(25)
sliding speed [m/s]
v
DIN EN 20 899-2
following
thread friction coefficient, see table 2 linear force [N], see section 4.1.1
FI
Table 5: Flexural creep modulus values based
The
on
852)
Fig.
5: Helical thread
(schematic)
Flexural creep modulus
[N/mm2],23C,
Material
ob
=
10 N/mm2
1-min value
6-day
value
Hostaform C 9021
2800
1500
Hostaform C 9021 GV 1/30
9000
7000
Hostalen PPN 1060
1300 1}
Hostacom M2 N02
16002)
Hostacom M4 N01
3300
1600
Hostacom G2 N02
4000
2400
Hostacom G3 N01
5500
3800
Celanex 2500
2800
2000
Celanex 2300 GV 3/30
4100
2900
Celanex 2300 GV 1/20
7100
5900
Celanex 2300 GV 1/30
9500
8600
:> ob
=
T _
500 2)
6 N/mm2
The
changes in flank diameter AD2 and Ad2 also approximately correspond to the diameter changes ZlDm and
With flank pressure p from
^dm,
equation (9)
B
P
[N/mm2]
=
n
z
_x
OS u<
^5 v/,\
%a
*
"5
30
40
20
10
0%
large notch factor K which results can lead to fail of the component at this point when under internal ure in pressure stress. Thread runouts such as described
Proportion of load taken by the forcetransmitting thread
The
flights
DIN 76 part 1 and part 3
must
be avoided with
molded threads; the thread flight on the mold end with the complete thread profile.
Static
6.3
sealing of plastics components
integrally
core must
with
integrally
molded threads 20 10
30
40
0%
basically take place outside the thread, i.e. no seals (hemp, sealing tape) should be used in the thread. In the case of flexible, deformable plastics (e.g. polyethyl ene, elastomer-modified plastics), the components can be sealed with molded-on sealing lips or other readily deform able zones (fig. 13). Sealing
Proportion of load taken by the forcetransmitting thread
flights
By introducing is
designed
distributed effect are
can
to
the end of the nut, this region yielding and hence the load is evenly over the thread flights. A similar
a recess at
be
more
more
fitting with internal part forced polypropylene and cap screw
injection mold by on
13: Screw closure with
integral
seal
rigidity. Example: glass-fiber-rein
made from nut
from unreinforced PP.
Stress concentration in the thread runout
The internal thread of the
Fig.
be achieved if the internal and external parts
made from materials with different
6.2.3
should
cores are
a
a core
plastics molding
generally machined,
a runout
an
curvature on
is
produced
a V-notch with very the internal thread (fig. 12).
the external thread which forms
small radius of
is formed in
with external thread. Because In the
case
of
hard, rigid plastics, additional seals
must
be used.
15
A
is sealed when the
joint
contact
pressure in the seal is
greater than the pressure difference between the sides of the seal.
Fig,
14: Flat
two
Fig.
15: Automatic
sealing effect with
elastic seals
Seal located in sealing groove
gasket
Seal compressed but not
pressure-loaded Squeezing process result of initial compression as a
Pv
Seal,
pressure-loaded Squeezing process result of initial compression as a
and
gaskets (fig. 14), because of the relatively large contact require high prestressing forces Fy to achieve a satis factorily high contact pressure. Owing to bedding down
PB
area,
stressed thread
cause
a more
the
_
=
p + pv
relaxation in the tensile-
a
are not
result, the joint
can
16: Triangular and rectangular grooves, axial deformation of O-rings
Fig.
leak.
O-rings placed which
stress
these prestressing forces
but decrease with time. As
constant start to
zones,
po
pressure p
Flat
processes in the thread and
sealing
in
them
appropriately dimensioned to
suitable solution. The force
rings
and thus
than is the
grooves
be deformed in the closed
to create contact
with flat
In
required
to
joint
are
deform
pressure is much less addition, O-rings have
gaskets. advantage that the contact pressure necessary for sealing is increased by the pressure of the medium being sealed, fig. 15. case
the
O-rings
can
be installed in
rectangular
fig. specified by the manufacturer grooves,
and
triangular
16. The groove dimensions and tolerances
should be observed.
In the
Fig.
in the
of the
examples shown in fig. 16, the O-rings are deformed longitudinal direction by prestressing force Fv. The arrangement in fig. 17 is more favorable, in which defor mation of the O-ring is achieved by suitable dimensioning of the internal and external parts and is not dependent on a
prestressing force.
16
Rectangular groove, radial deformation O-ring
17:
If
Injection molding of
7.
components with molded threads
even
integrally
External thread
be visible, the thread must sleeve which is unscrewed after
Depending
The external thread forms external undercuts in slides. that allow mold
Fig.
are
released
movement
by
allowed
to
a single threaded injection molding.
on
the intended
requirements,
length of the production run demolding options may
various
be considered.
the action of
of the slides
opening direction, fig.
are not
Internal thread
and thread These undercuts
marks from the slides
be formed in
7.2
7.1
parting
angle pins right angles to the
at
For short runs, so-called lost
cores are
inserted into the
injection mold and ejected with the part after injection molding. Outside the mold, the core is then unscrewed manually or with a special device. For longer runs, the
18.
18: Slide mold for external thread
threaded
cores are
unscrewed inside the mold. The
produced either with the aid of a coarsely threaded spindle via the mold opening movement or via a hydraulically operated rack and pinion system or drive motor.
necessary rotary
Fig.
In the
contact area
of the
slides, flash
can
be formed
20:
movement
is
Unscrewing mold for internal thread
as a
particular molding conditions or wear. This flash makes it difficult or even impossible to screw the threaded parts. The problem can be avoided by flattening result of the
the thread in the will then lie not
be
Fig.
an
out
area
of the
contact
of the way of the
obstruction, fig.
surfaces.
opposing
Any flash
thread and
19.
19: Slides with flattened thread
Another way to demold internal threads is to use a collap sible core. This type of core is divided into segments
which
collapse thread, fig. 21.
inwards
so
permitting
release of the
17
Fig. 21: Collapsible core, left: injection molding position, right: demolding position
Fig.
22:
Segmented internal thread
Manufacturer/sales :
DME-Zentrale, 74196 Neuenstadt, Germany Rudolf Riedel GmbH, 58579 Schalksmühle, Germany
demoldabie undercut
Internal threads via
angle slides,
can
if
a
be demolded much continuous thread is
instead individual threaded segments the linear force FI, fig. 22.
18
are
simply, i.e. not required but
more
sufficient
to
take
In
general it
should be noted that
thread shrinks
onto
the threaded
a
molding with
core
internal
and that with in-
creasing cooling time the shrinkage forces also increase. With unscrewing cores in particular, this can lead to demolding difficulties if the prescribed cooling time is exceeded, e.g. in the event of interruptions to production.
8.
Examples of applications
8.1
Water filter
Photo 1 shows
housing
a water
form C 9021. The
two
Drain plug for
8.2
filter
housing made from Hostahousing halves are screwed
together with an S 80 x 4 buttress thread; the number of loadbearing thread flights z 2. This housing, which is constantly under mains water pressure, is sealed with an axially deformed O-ring. The wall thickness of the
The drain
plug
water
shown in
into the base of the
separator
photo
water
2 and
on
diesel vehicles
fig.
separator with
23 is an
screwed
M 10
x
1.5
thread.
=
internal part pans
s2
=
si
4.4
=
6.1 mm; the wall thickness of external
mm.
The external thread is formed in splits; the core the internal thread is unscrewed in the mold.
forming
The
plug is
sealed with
O-ring. The plug is held captive housing by two snapfit hooks. To achieve the required deformability for snapfitting, the screw bolt is centrally bored and laterally recessed. an
in the separator
Although
the transition from the
is well rounded
(R
=
0.8
screw
mm), fig.
23
bolt
left,
to
the
stress
flange cracking
occurred in this runout.
thread and
Fig.
region owing to the sharp-edged thread problem was remedied by shortening the ending it with a complete profile, fig. 23 right.
This
23: Drain
plug
19
hopper for corn mill
Grain
8.3
This
hopper (photo 3)
an
M 90
80
x
x
depth HI
made from Hostalen PPT 1070 has
2 metric external thread and
20 P 4 =
a
non-standard
five-start, rectangular internal thread, thread 1
Fastening nut for spare wheel
8.4
mm.
The
nut
(PP
+
fasten the spare wheel of a car onto The M 8 x 1.25 nut thread is however to
formed The external thread is formed in
two
slides. The internal
thread is divided into two threaded segments, each cover ing an angle at the circumference of 120. The thread is
demolded via core.
two
slides
running
on
the
tapered
inner
photo 4 made from Hostacom G3 N01 glass fibres, chemically coupled) is used
shown in
30% w/w
only
over
the thread reach, The threaded to
push
the
a
threaded bolt.
not
complete
but
half the circumference in each half of
fig.
24.
areas are
slightly
offset
tilted
by 180. nut quickly
This makes it easy over the threaded
bolt.
Only through contact with the spare wheel is the axis of the nut aligned with the axis of the threaded bolt so that the thread flights of the nut and bolt can become engaged and the nut tightened up. Fig.
20
24:
Interrupted M
8
x
1.25 thread
Explanation of symbols
9.
Symbol
Unit
A,, 2
mm2
Explanation
Symbol
Unit
Explanation
vulnerable cross-section,
M
N-m
tightening
n
min"1
spindle speed
P
N/mm2
flank pressure
PD
N/mm2
pressure
p;
N/mm2
internal pressure
Pperm.
N/mm2
permissible
W/mm2
material-dependent design
torque
notch cross-section thread
thread reach
B, L
mm
engaged
C
mm2
thread
mm
nominal thread diameter
d2,D2
mm
thread flank diameter
d3
mm
thread
d,
D
overlap
core
zone, area
p
dA
mm
mean
v
value
dimension for helical gears and slide bearings
diameter of the
contact
surface
di
mm
inside diamter of
dp
mm
diameter of the
a
joint
pressure-stressed
p
mm
thread
PR
W
frictional energy
PN
bar
nominal pressure
R
mm
radiusing
s
mm
wall thickness
v
m/s
sliding speed
Ç11 t"T3 PP dU.1 let L/C
dm, Dm
mm
mean
Da
^\
diameter
mm
outside diameter of
E
N/mm2
flexural creep modulus
fA
D
a
joint
z
-
_
friction coefficient of the
_
surface
thread friction coefficient force
FB
N
operating
Fi
N
linear force
F
N
perpendicular
Fr
N
radial force
Fv
N
prestressing force
force
o
a
K,
mm
thread
H5
mm
flank
helix
loadbearing flights
angle
Kö,
KS
a*
-
-
notch factors
load-dependent
ß
o
half
r
o
angle
Oz
angle
notch factor
of thread
of friction
strain
e
"perm.
H,,h3, H4, c
number of
thread
friction coefficient
contact
fc
+
pitch
2
Da
f
flank pressure
diameter
N/mm2
tensile
N/mm2
permissible
stress
tensile
stress
depth
overlap
21
10. Literature
[1]
[9] DIN
DIN 2244
installation, Anforderungen, Prüfungen, techn.
[2] DIN 202 Gewinde, Übersicht [3] DIN 13, Bl. l Metrisches ISO-Gewinde.
Regelgewinde
von
l bis 68
Regeln
von
Feingewinde 40 bis 300
DIN 13, Bl. 12 300
Regel-
mm
mit
mm
und
[11]
H. Neuber:
Sanitär armaturen
Steigung
4
Über die Berücksichtigung der Spannungs
mm
von
l bis
Gewindedurchmesser. Auswahl
für Durchmesser und
[4]
DIN EN 200
konzentration bei
Gewindedurchmesser.
Feingewinde
Steigungen.
viskoelastischem Materialverhalten Plaste und Kautschuk 35
Metrisches
Sägengewinde (Gewindedurchmesser 10 bis
620
mm)
[13]
ISO-Trapezgewinde (Gewindedurchmesser 8 bis 300 mm)
[7] DIN
Tl. 2
[8]
K.
Bordas,
Berechnung
vorzugsweise Sägengewinde Trapezgewinde
von
Konstruktion 37
[15]
p. 67
im
Schraubengewinde
DIN 76, Tl. l
Bergner, Schwabach
A. Oedekoven:
Trapezgewinden (1985) l,
p. 25
+ 3
Gewindeausläufe, Gewindefreistiche
6063
für Kunststoffbehältnisse
[16]
H. Gastrow:
Der
Spritzgießwerkzeugbau in 100 Beispielen Verlag, Munich Vienna 1990
Carl Hanser
DIN 405
Rundgewinde (Gewindedurchmesser
22
[14] G. Pahl,
für nicht im Gewinde dichtende
Gewinde Tl. l
(1988) 2,
Kloos,W. Thomala:
Firmenschrift der Fa. Richard
DIN/ISO 228
Rohrgewinde Verbindungen
K.H.
Spannungsverteilung
103
Metrisches
[6]
Festigkeitsberechnungen
Konstruktion 20 (1968) 7, p. 245 [12] E.Weiß: Zur Berücksichtigung der Kerbwirkung bei
DIN 513
[5] DIN
des DVGW
[10]
mm
Gewindedurchmesser. DIN 13, Bl. 9
19632
Mechanisch wirkende Filter in der Trinkwasser
Gewinde, Begriffe
8 bis 200
mm)
In this technical information
Engineering plastics Design Calculations Applications
provide exploit the properties Hostaform.
Publications
A.
so
far in this series:
Engineering plastics A. 1 1 Grades and properties A. 1.2 Grades and properties A. 1.4 Grades and properties A. 1.5 Grades and properties Vandar, Impet A.2.1 Calculation principles
to
.
A.2.2 Hostaform
calculation A.2.3
Hostacom calculation
B.
-
advise you
designers who of engineering polymers
Our technical service on
-
-
-
Hostaform Hostacom Hostalen GUR
Celanex,
Characteristic values and
and is intended
edge products strued
and their
to
uses.
on our
not
such
as
will be
present
provide general It should
to
want to
pleased processing.
team
materials, design and
This information is based -
brochure, Hoechst aims
useful information for
state
of knowl
notes on our
therefore be
con
guaranteeing specific properties of the products described or their suitability for a particular application. Any existing industrial property rights must be observed. The quality of our products is guaranteed under our as
General Conditions of Sale.
examples -
Characteristic values and
examples
Design of technical mouldings B. 1.1 Spur gears with gearwheels made from Hostaform, Celanex and Hostalen GUR B.2.2 Worm gears with
worm
Applications involving the use of the Hoechst materials Hostaform, Hostacom, Hostalen PP and Celanex are developments or products of the plastics processing industry. Hoechst as manufacturers of the starting mate rial will be pleased to give the names of other processors of plastics for engineering applications.
wheels made from
Hostaform B.3.1
B.3.2 B.3.3 B.3.4
B.3.5 B.3.7
Design calculations for snapfit joints in plastic parts Fastening with metal screws Plastic parts with integrally moulded threads Design calculations for press-fit joints Integral hinges in engineering plastics Ultrasonic welding and assembly of emgineering plastics
C. Production
of technical mouldings runner system Indirectly heated, thermally conductive torpedo Hot runner system Indirectly heated, thermally conductive torpedo Design principles and examples of molds for processing Hostaform Machining Hostaform Design of moldings made from engineering plastics Guidelines for the design of moldings in engineering plastics Outsert molding with Hostaform
C.2.1 Hot
C.2.2
C.3.1 C.3.3 C.3.4
C.3.5
-
-
©
Copyright by
Issued in
August
Hoechst
Aktiengesellschaft
1996/1 st edition
23
Hostaform ® , Celcon ®
polyoxymethylene copolymer (POM)
Celanex®
thermoplastic polyester (PBT)
Impet ®
thermoplastic polyester (PET)
Vandar®
thermoplastic polyester alloys
Riteflex®
thermoplastic polyester elastomer (TPE-E)
Vectra ®
liquid crystal polymer (LCP)
Fortron ® polyphenylene sulfide (PPS)
Celstran ® , Compel ®
long fiber reinforced thermoplastics (LFRT)
GUR ®
ultra-high molecular weight polyethylene (PE-UHMW)
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