B.3.3 Plastic Parts With Integrally Molded Threads, Farbig

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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