U.S. patent application number 11/403431 was filed with the patent office on 2006-11-16 for injection molding nozzle.
Invention is credited to Swen Spuller.
Application Number | 20060257521 11/403431 |
Document ID | / |
Family ID | 36586033 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060257521 |
Kind Code |
A1 |
Spuller; Swen |
November 16, 2006 |
Injection molding nozzle
Abstract
In an injection molding nozzle with a nozzle head including at
least one discharge opening and a closure element for closing the
discharge opening movably supported in the nozzle head for closing
the discharge in order to control the supply of melt material to a
communication opening in an injection mold, the closure element is
operable by a drive mechanism provided with a short stroke
actuating means for displacing the closure element in a direction
opposite to the closing direction of the closure element by a
predetermined short distance so as to automatically retract the
closure element by the predetermined short distance when it is no
longer biased by the actuating means in the closing direction.
Inventors: |
Spuller; Swen; (Forchheim,
DE) |
Correspondence
Address: |
KLAUS J. BACH & ASSOCIATES;PATENTS AND TRADEMARKS
4407 TWIN OAKS DRIVE
MURRYSVILLE
PA
15668
US
|
Family ID: |
36586033 |
Appl. No.: |
11/403431 |
Filed: |
April 13, 2006 |
Current U.S.
Class: |
425/564 |
Current CPC
Class: |
B29C 2045/2779 20130101;
B29C 2045/2872 20130101; B29C 45/281 20130101; B29C 2045/2841
20130101; B29C 2045/2813 20130101; B29C 45/44 20130101; B29C
45/2735 20130101; B29C 2045/2831 20130101 |
Class at
Publication: |
425/564 |
International
Class: |
B29C 45/20 20060101
B29C045/20 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2005 |
DE |
102005017413.2-16 |
Claims
1. An injection molding nozzle with a nozzle head (11) including at
least one discharge opening (1), a positively controlled closure
element (2) movably supported in the nozzle head (11) for closing a
communication opening in an injection mold (4), and short stroke
actuating means for displacing the closure element (2) in a
direction opposite to the closing movement direction (6) thereof by
a predetermined short stroke distance.
2. An injection molding nozzle according to claim 1, wherein the
short stroke distance is 0.05 to 1 mm.
3. An injection molding nozzle according to claim 1, wherein the
short stroke distance is about 0.3 mm.
4. An injection molding nozzle according to claim 1, wherein the
nozzle head (11) is connected to a drive (7) for operating the
closure element (2), said drive (7) including said short stroke
actuating means in the form of a return element (5) having an
operating position and a rest position to which the return element
(5) returns when the drive (7) is in-activated.
5. An injection molding nozzle according to claim 4, wherein the
return element (5) is a plate spring.
6. An injection molding nozzle according to claim 1, wherein the
nozzle head (11) includes at least two discharge openings (1)
oriented in opposite directions and having closure element (2)
operable by a control means (8).
7. An injection molding nozzle according to claim 1, wherein the
closure elements (2) are positively controlled via a slide guide
structure (9).
8. An injection molding nozzle according to claim 4, wherein the
closure elements (2) are closure needles which extend through the
discharge openings (1) and are provided at their ends (2b) opposite
the discharge openings (1) with a T-shaped engagement structure,
and the drive means (7) includes a control rod (8) having a
wedge-shaped end disposed in the nozzle head (11) and being
provided with a T-shaped groove (9) in which the T-shaped
engagement structures of the closure elements (2) are received for
actuating the closure elements (2) by axial movement of the control
rod (8).
9. An injection molding nozzle according to claim 8, wherein the
closure elements (2) are provided at their ends with cylindrical
sections (2a) extending into the discharge openings (1) for closing
the discharge openings (1).
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to an injection molding nozzle with at
least one opening and a positively controlled closure element by
which a communication opening of an injection mold can be
closed.
[0002] Such an injection molding nozzle is known for example from
DE 38 43 035 A1. The known injection molding nozzle includes, at
the end of a supply channel for a plastic material melt, a
discharge opening through which a closure needle extends. By means
of the closure needle a discharge opening of an injection mold
which is in communication with the injection molding nozzle can be
closed. In this way, on one hand, the supply of plastic material
melt through the discharge opening to the injection mold can be
interrupted and, on the other hand, a backflow of plastic melt out
of the injection mold can be prevented.
[0003] Such an injection molding nozzle is also described in DE 102
31 093 A1. This known injection molding nozzle includes two
discharge openings which are oriented in opposite directions and
through each of which a closure needle extends by which a
communication opening of an injection mold can be closed. Each
discharge opening is in communication with a supply channel for
plastic material so that plastic material can flow through the
discharge openings and be supplied to the communication opening of
the injection molds.
[0004] For closing the mold communication openings, the closure
needles of the known injection molding nozzles are axially moved so
that they extend into the communication openings of the respective
injection molds to sealingly close them. In order to obtain a
fault-free surface of the injection molding part to be
manufactured, it is necessary that the closure needles extend
sufficiently far into the communication openings so that the tips
of the closure needles are disposed in planar alignment with the
surface of the respective injection molding part. This requires
extensive adjustment work.
[0005] If the closure needle does not extend sufficiently far into
the communication opening, that is, if the tip of the needle is
disposed at a distance from the surface of the respective injection
molding part, a small grafting is formed at the gate mark. If the
closure needle extends into the communication opening beyond the
surface for the respective molding part, the surface of the
injection molding part may be scratched upon removal from the
injection mold which renders the injection molding part
unusable.
[0006] It is the object of the present invention to provide an
injection molding nozzle by which a fault-free injection molding
part can be produced without the need for time-consuming
adjustment.
SUMMARY OF THE INVENTION
[0007] In an injection molding nozzle with a nozzle head including
at least one discharge opening and a closure element for closing
the discharge opening movably supported in the nozzle head for
closing the discharge in order to control the supply of melt
material to a communication opening in an injection mold, the
closure element is operable by a drive mechanism provided with a
short stroke actuating means for displacing the closure element in
a direction opposite to the closing direction of the closure
element by a predetermined short distance so as to automatically
retract the closure element by the predetermined short distance
when it is no longer biased by the actuating means in the closing
direction.
[0008] By the means with which the closure element is operable by a
short stroke distance in a direction opposite to the closing
direction, the closure element may first be so adjusted that it
extends slightly into the injection molding part so that no
grafting can be formed and, upon retraction by the short stroke
distance, is disposed slightly spaced from the injection molding
part so that the injection molding part cannot be scratched when it
is removed from the mold. Consequently, the injection molding parts
can always be manufactured in perfect condition.
[0009] With the short stroke actuating means, an actuating
adjustment of the closure element position is not necessary. Since
the closure element first projects into the injection molding part
but is retracted immediately after the injection molding step so
that it is disposed at a distance from the injection molding part,
the closure element does not need to have an accurately controlled
closing position.
[0010] It is very advantageous if the short stroke has a stroke
length of 0.05 to 1 mm, particularly 0.1 to 0.5 mm and preferably
0.3 mm. Then a safe closure of the gate mark opening of the
injection mold can be obtained and a sufficiently large distance of
the closure element from the surface of the injection molding part
is ensured.
[0011] Preferably, the closure element is provided with a drive
which includes a return element which has an operating position and
a rest position when the drive is inactivated. Since the drive
includes a return element, the short stroke in a direction opposite
to the closing direction of the closure element is realized in a
simple way.
[0012] When the drive operates the closure element, the return
element is moved to its operating position in which the closure
element extends into the injection molding part. After the closure
element has reached its end position, the return element moves from
its operating position to its rest position, whereby the closure
element is moved a small distance counter to the closing direction
so that the closure element no longer extends into the injection
molding part, but is disposed at a distance from the injection
molding part. With the return element, the short stroke actuation
can be performed in a simple manner and very accurately.
[0013] Preferably, the return element is in the form of a plate
spring. Such a return element is easy to manufacture and operates
very accurately and reliably.
[0014] However, the return element may also be a separate
pneumatically or hydraulically operated element or another element
used in the field of injection molding as closure needle drive
system such as a short stroke cylinder, which can generate a large
force while occupying little space.
[0015] In another special embodiment at least two openings oriented
in different directions are present, whose closure elements are
adjustable by an adjustment device. The drive for the closure
elements may act on a common operating member. In this way, the
short stroke in a direction opposite to the closing direction can
be executed for all closure elements at the same time.
[0016] Furthermore, the closure elements are moved synchronously
and uniformly since the closure elements are operated by a common
operating member. This also means that the communication openings
are opened or, respectively, closed all in the same way. This
results in a very uniform filling of the injection mold, which is
very advantageous for the quality of the injection molding
parts.
[0017] Preferably, the closure elements are controlled by a guide
slide structure, which provides for a very precise movement of the
closure elements.
[0018] An embodiment was found to be particularly advantageous
wherein the closure elements are in the form of closure needles
which extend through the discharge openings and are T-shaped at
their ends opposite the discharge openings and arranged each in a
T-groove of a central rod, the T-groove extending along a cone or
wedge. Such a control arrangement for the closure elements can be
realized in simple way and operates precisely and reliably.
[0019] Since the closure elements can move relatively far into the
communication openings of an injection mold, the closure needles
can have cylindrical ends which extend through the discharge
openings. This simplifies the manufacture of the closure needles
substantially.
[0020] Further features and advantages of the invention will become
more readily apparent from the following description of a
particular embodiment with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 and FIG. 1a show an injection molding nozzle with two
discharge openings which are disposed at the side thereof and into
which closure needles extend which are adjustable by a central
control rod for closing a communication opening of an injection
mold, the closure needles being shown in a retracted position in
which the communication openings are not closed.
[0022] FIG. 2 and FIG. 2a show the injection molding nozzle of FIG.
1, wherein however the closure needles are shown in a position in
which they close the communication openings,
[0023] FIG. 3 and FIG. 3a show the injection molding nozzle of FIG.
1, wherein the closure needles are shown in a position in which the
communication openings are closed but the needles retracted by the
length of a short stroke,
[0024] FIG. 4 is a cross-sectional view taken along line A-A of
FIG. 1, and
[0025] FIG. 5 is a cross-sectional view taken along line B-B of
FIG. 2.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0026] FIGS. 1-3 show an injection molding nozzle body 11 provided
with a nozzle head 12, which has two discharge openings 1 extending
in opposite directions and two closure needles 2 with tips 2a for
closing the discharge openings 1. The closure needles 2 are
supported in the nozzle head 12 so as to be axially movable
therein. At their tips 2a adjacent the discharge openings 1, the
closure needles 2 have cylindrical control areas. At their ends 2b,
opposite the discharge openings 1, the closure needles 2 have an
enlarged diameter providing for a T-shaped cross-section.
[0027] A control rod 8 extends centrally through the nozzle body 11
and is axially movably supported in the nozzle body 11. At its end
adjacent the nozzle head 12, the rod 8 is provided with an enlarged
control area which is wedge-shaped or conical. This pointed area
forms a bottom or, respectively, groove base of axially extending
T-shaped grooves 9, in which the T-shaped ends of the closure
needles 2 are disposed so that the movement of the closure needles
2 can be positively controlled by axial movement of the conical rod
8.
[0028] The nozzle body 11 is provided with a nozzle carrier ring 13
which is connected to a distributor block 14.
[0029] The control rod 8 extends through the nozzle carrier ring 13
to which the nozzle body 11 is connected, and also through the
distributor block 14, with which the nozzle carrier 13 is
connected. At its end remote from the nozzle head 12, the control
rod 8 is provided with a double-piston 7 disposed in an operating
cylinder which includes two chambers 7a, 7b. In the lower chamber
7b, a plate spring 5 is disposed which is compressed at the end of
the control movement of the piston 7 before reaching its lower end
position.
[0030] Through the distributor block 14, the nozzle carrier 13, the
nozzle body 11 and the nozzle head 12, a supply passage 15 extends
for supplying melt material to the discharge openings 1 of the
injection molding nozzle. The supply passage 15 is in open
communication with the discharge openings 1, so that the melt can
leave the nozzle head 12 via the discharge openings 1.
[0031] The discharge openings 1 of the nozzle head 12 are each
provided with a communication opening 3 of a mold insert 4. The
mold inserts 4 have cavities 4a into which the melt material
leaving the discharge openings 1 can be injected via the
communication openings 3.
[0032] As apparent particularly from the enlarged detail
representation of FIG. 1a, the closure needle 2 is disposed
essentially completely within the nozzle head 12 wherein the
pressure piston 7 is in its rest position that is at the upper end
of the chamber 7a, 7b as shown in FIG. 1. In this position, the
communication openings 3 are fully open so that the plastic melt
can flow out of the discharge openings 1 into the cavities 4a of
the mold inserts 4 via the communication openings 3.
[0033] With the application of pressure to the pressure cylinder,
the double piston 7 moves downwardly into the lower part of the
chambers 7a, 7b. As a result, the rod 8 is moved into the nozzle
head 12 whereby the closure needles 2 are moved toward the
communication openings 3.
[0034] As apparent from the enlarged section of FIG. 2a, when the
double piston 7 is at the bottom end of the chambers 7a, 7b, the
closure needles 2 extend fully through the communication openings 3
and slightly into the cavities 4a or, respectively, into the melt
material in the cavities 4a which, meanwhile, have been filled with
melt materials.
[0035] When the piston 7 has reached its lowermost position in the
chambers 7a, 7b, the cylinder operating pressure is released. As a
result, the plate spring 5 relaxes and moves the piston 7 and,
together therewith, the control rod 8 slightly upwardly.
[0036] As a result of the positive engagement of the closure needs
2 with the control rod 8, the closure needles 2 are retracted, that
is, moved in a direction opposite to the closing direction 6 as
shown in FIGS. 3, 3a.
[0037] As shown in FIG. 3a, in this position, the communication
openings 3 are still closed. However, the closure needles 2 are no
longer disposed in the cavities 4a, but at a distance therefrom
that is, at a distance from the injection-molded parts. As a
result, the injection-molded parts can be removed from the molds
without chances of being scratched at their surfaces by the closure
needles 2.
[0038] The positive control of the closure needles 2 is shown in
FIGS. 4 and 5. As shown in the FIGS. 4 and 5, the pointed end of
the control rod 8 includes T-shaped grooves in which the T-shaped
ends 2b of the closure needles 2 are received.
[0039] FIG. 4 shows the position of the rod 8 corresponding to FIG.
1, wherein the closure needles 2 are fully retracted so that they
are disposed essentially fully within the nozzle head 12.
Particularly the ends 2a of the closure needles 2 are disposed
spaced from the communication openings 3 of the mold inserts 4 so
that melt can flow out of the discharge openings 1 of the nozzle
head 12 via the communication openings 3 of the mold inserts 4 into
the mold cavities 4a.
[0040] FIG. 5 shows the control rod 8 in a position corresponding
to FIG. 2, wherein the closure needles 2 are moved to their outer
end positions. In this position, the front ends 2a of the closure
needles 2 extend into the communication openings 3 and close the
communication openings 3 so that no melt can enter the cavities 4a
of the mold inserts 4 or flow out of the cavities 4a.
* * * * *