U.S. patent application number 12/243609 was filed with the patent office on 2009-03-12 for apparatus and method for manufacturing multi-component plastic molded parts.
This patent application is currently assigned to KraussMaffei Technologies GmbH. Invention is credited to Marco Gruber, LUDWIG JUNG, Andreas Reitberger.
Application Number | 20090065973 12/243609 |
Document ID | / |
Family ID | 38198247 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090065973 |
Kind Code |
A1 |
JUNG; LUDWIG ; et
al. |
March 12, 2009 |
APPARATUS AND METHOD FOR MANUFACTURING MULTI-COMPONENT PLASTIC
MOLDED PARTS
Abstract
In a method of making multi-component plastic molded parts,
using an apparatus which includes two outer platens with first
half-molds, and a middle platen with second half-molds interacting
with the first half-molds such as to define cavities in two parting
planes for injection of a plastic melt and/or a PUR mixture, one of
the first and second half-molds can move in increments relative to
the other one of the first and second half-molds, thereby forming
different cavities in the parting planes from cycle to cycle. In a
first cycle preforms are produced in respective cavities and then
held in one of the first and second half-molds as the other one of
the first and second half-molds moves in increments. Further
components can then be injected into cavities formed in the parting
planes from cycle to cycle, while another process step can be
executed from cycle to cycle in free half-molds.
Inventors: |
JUNG; LUDWIG; (Mammendorf,
DE) ; Gruber; Marco; (Munchen, DE) ;
Reitberger; Andreas; (Deggendorf, DE) |
Correspondence
Address: |
Henry M. Feiereisen;Henry M. Feiereisen, LLC
708 Third Avenue, Suite 1501
New York
NY
10017
US
|
Assignee: |
KraussMaffei Technologies
GmbH
Munchen
DE
|
Family ID: |
38198247 |
Appl. No.: |
12/243609 |
Filed: |
October 1, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2007/053264 |
Apr 3, 2007 |
|
|
|
12243609 |
|
|
|
|
Current U.S.
Class: |
264/254 ;
425/112 |
Current CPC
Class: |
B29K 2075/00 20130101;
B29C 2045/1617 20130101; B29C 45/1628 20130101; B29C 45/84
20130101; B29C 45/1615 20130101; B29C 37/0032 20130101; B29C 67/246
20130101; B29C 45/561 20130101; B29C 45/045 20130101; B29C 45/32
20130101; B29C 45/1671 20130101 |
Class at
Publication: |
264/254 ;
425/112 |
International
Class: |
B28B 7/26 20060101
B28B007/26 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2006 |
DE |
10 2006 016 200.5 |
Claims
1. A method of making multi-component plastic molded parts, using
an apparatus which includes two outer platens with outer first
half-molds, and a middle platen with middle second half-molds
interacting with the first half-molds such as to define cavities in
two parting planes for injection of a plastic melt and/or a PUR
mixture, said method comprising the steps of: allowing one of the
first and second half-molds to move in increments in relation to
the other one of the first and second half-molds to thereby form
different cavities in the two parting planes from cycle to cycle;
producing in a first cycle preforms in the cavities respectively
formed in the two parting planes between respective ones of the
first and second half-molds; holding the preforms in one of the
first and second half-molds as the other one of the first and
second half-molds moves in increments and injecting further
components into the cavities formed in the two parting planes from
cycle to cycle; and allowing from cycle to cycle to execute a
pretreatment or another process step in free ones of the first and
second half-molds.
2. The method of claim 1, wherein the middle platen has a
cube-shaped or prism-shaped configuration, said moving step
including the step of rotating the middle platen in relation to the
outer platens about a vertical axis or a horizontal axis, with the
different cavities being formed in the two parting planes from
cycle to cycle.
3. The method of claim 1, wherein the middle platen has two
parallel platen areas, with one of the platen areas carrying a
first plurality of the second half-molds of the middle platen,
which cooperate with one of the first half-molds of the outer
platens, and the other one of the platen areas carrying a second
plurality of the second half-molds of the middle platen, which
cooperate with another one of the first half-molds of the outer
platens, said moving step including the step of linearly moving the
middle platen in increments in perpendicular relationship to a
longitudinal apparatus axis, with the different cavities being
formed in the two parting planes from cycle to cycle.
4. The method of claim 3, wherein the middle platen has a
plate-shaped configuration.
5. The method of claim 1, wherein one of the outer platens carries
a first plurality of the first half-molds and the other one of the
outer platens carries a second plurality of the first half-molds,
said moving step including the step of linearly moving the outer
platens in increments in relation to the middle platen.
6. The method of claim 1, wherein one of the outer platens carries
a first plurality of the first half-molds and the other one of the
outer platens carries a second plurality of the first half-molds,
said moving step including the step of rotating the outer platens
in increments in relation to the middle platen.
7. The method of claim 1, wherein the producing step includes the
step of molding the preforms from a thermoplastic component in the
two parting planes, and further comprising the step of flooding the
preforms with a PUR mixture in the two parting planes in a second
cycle.
8. The method of claim 1, wherein the producing step includes the
step of molding the preforms from a thermoplastic component in the
two parting planes, and further comprising the step of molding a
second thermoplastic component onto the preforms.
9. The method of claim 1, wherein the producing step includes the
step of molding the preforms from a first PUR mixture in the two
parting planes, and further comprising the step of flooding the
preforms with a second PUR mixture in the two parting planes in a
second cycle.
10. The method of claim 1, wherein the pretreatment or other
process step involves one process selected from the group
consisting of preheating, addition of a mold release agent, venting
of the mold release agent, cleaning, addition of varnish for an In
Mold Coating process, and placing and securing at least one of
insertion parts and decoration materials.
11. The method of claim 10, wherein the at least one of the
insertion parts and decoration materials is selected from the group
consisting of fabrics, foils, aluminum strips, and metal
strips.
12. The method of claim 1, further comprising the step of
successively opening the parting planes.
13. The method of claim 12, wherein the parting planes are opened
when PUR mixtures in the two parting planes have different reaction
times or the preforms in the two parting planes have different
cooling periods.
14. The method of claim 1, for the production of a pair of plastic
molded parts, comprised of a right part and a left part, wherein
the right part is produced in one of the parting planes; and the
left part is produced in the other one of the parting planes.
15. The method of claim 1, for the production of different plastic
molded parts, wherein a main component is produced in one of the
parting planes; and a plurality of accessory components are
produced in the other one of the parting planes.
16. The method of claim 9, further comprising the step of heating
the half-mold with the first PUR mixture before the flooding
step.
17. The method of claim 16, wherein the heating step is executed
while the preform is produced.
18. The method of claim 9, further comprising the step of
subjecting the PUR mixture to a compression during the flooding
step to contract or expand the cavity formed in the respective one
of the parting planes.
19. The method of claim 18, wherein contraction or expansion of the
cavity is implemented by moving half-molds or inserts in the
half-molds relative to each other.
20. The method of claim 1, wherein the execution of the
pretreatment is performed by at least one operator; and further
comprising the step of providing a safety device and allowing a
movement of machine parts only when the at least one operator
actuates the safety device.
21. The method of claim 20, wherein the machine parts involve the
middle platen or movable outer platens.
22. The method of claim 21, further comprising the steps of
defining a safety area, monitoring the safety area by light
barriers, and allowing a movement of the machine parts only when
the at least one operator has left the safety area and actuated the
safety device.
23. Apparatus for making multi-component plastic molded parts,
comprising: two outer platens having outer half-molds; a middle
platen positioned between the outer platens; and a clamping unit
for closing and locking four of the half-molds of the outer platens
and the middle platen at one time to thereby define two parting
planes; wherein the middle platen carries at least two of a first
type of half-molds that are different from each other and at least
two of a second type of half-molds that are different from each
other so as to successively form in the parting planes with the
half-molds of the outer platens different cavities while leaving
free half-molds for allowing pretreatment or a further process
step, and wherein the outer half-molds are constructed for holding
molded parts.
24. The apparatus of claim 23, further comprising at least one
member selected from the group consisting of injection units and
PUR facility, and constructed for docking on at least one of the
outer and middle platens and half-molds of the outer and middle
platens.
25. The apparatus of claim 23, wherein the middle platen has four
half-molds.
26. The apparatus of claim 23, wherein the middle platen is
constructed for rotation.
27. The apparatus of claim 23, wherein the middle platen has a
cube-shaped or prism-shaped configuration and is constructed for
rotation about a vertical axis or a horizontal axis so as to form,
from cycle to cycle, the different cavities in the parting
planes.
28. The apparatus of claim 23, wherein the middle platen has two
platen areas, said first type of half-molds being arranged on one
of the platen areas and cooperate with a half-mold of one outer
platen, and said second type of half-molds being arranged on the
other one of the platen areas and cooperate with a half-mold of the
other outer platen, said the middle platen constructed for linear
movement in increments in perpendicular relationship to a
longitudinal apparatus axis so as to form the different cavities in
the two parting planes from cycle to cycle.
29. The apparatus of claim 28, wherein the middle platen has a
plate-shaped configuration.
30. The apparatus of claim 23, wherein one of the outer platens is
fixed and the other one of the outer platen is movable, said middle
platen being movable longitudinally between the outer platens on a
sliding table.
31. The apparatus of claim 23, wherein the outer platens are
movable, said middle platen being fixedly arranged between the
outer platens and having a cube-shaped configuration, said middle
platen having two adjacent first half-molds cooperating with one of
the two movable outer platens and two adjacent second half-molds
cooperating with the other one of the two movable outer
platens.
32. The apparatus of claim 23, wherein the PUR facility is docked
onto each of the half-molds of the outer platens and includes two
injection units and two mixing head docked onto the half-molds of
the outer platens in one-to-one correspondence.
33. The apparatus of claim 23, wherein half-molds of one of the
parting planes are constructed for the production of a right part
of a pair of plastic molded parts, and half-molds of the other
parting plane are constructed for the production of a left part of
the pair of plastic molded parts.
34. The apparatus of claim 23, wherein half-molds of one of the
parting planes are constructed for the production of a main
component, and half-molds of the other parting plane are
constructed for the production of at least one accessory
component.
35. The apparatus of claim 30, further comprising a safety device
adapted for actuation by an operator, and a safety area monitored
by light barriers, wherein a movement of a machine part can be
blocked and released depending on the safety device and the safety
area.
36. The apparatus of claim 35, wherein the machine part is the
middle platen.
37. The apparatus of claim 23, further comprising at least one
dummy mold provided in one of the parting planes.
38. Apparatus for making multi-component plastic molded parts,
comprising: two outer platens, each having mounted thereon a
plurality of half-molds; a middle platen positioned between the
outer platens; a clamping unit for closing and locking four of the
half-molds of the outer platens and the middle platen at one time
to thereby define two parting planes; wherein the middle platen has
a plurality of mold halves which are constructed to hold molded
parts, wherein the outer platens move in increments in relation to
the middle platen to thereby form in increments different cavities
in the two parting planes and leaving free half-molds for allowing
pretreatment or a further process step.
39. The apparatus of claim 38, further comprising at least one
member selected from the group consisting of injection units and
PUR facility, and constructed for docking on at least one of the
outer and middle platens and half-molds of the outer and middle
platens.
40. The apparatus of claim 38, wherein the outer platens move
linearly in relation to the middle platen.
41. The apparatus of claim 38, wherein the outer platens rotate
about a horizontal axis in relation to the middle platen.
42. The apparatus of claim 38, wherein the outer platens are
constructed in the form of sliding tables which are linearly
movable in perpendicular relationship to a longitudinal apparatus
axis.
43. The apparatus of claim 38, wherein the outer platens are
constructed in the form of rotary tables which are rotatable about
a horizontal axis.
44. The apparatus of claim 38, wherein one of the outer platens is
fixed and the other one of the outer platen is movable, said middle
platen being movable longitudinally between the outer platens on a
sliding table.
45. The apparatus of claim 38, wherein the outer platens are
movable, said middle platen being fixedly arranged between the
outer platens and having a cube-shaped configuration, said middle
platen having two adjacent first half-molds cooperating with one of
the two movable outer platens and two adjacent second half-molds
cooperating with the other one of the two movable outer
platens.
46. The apparatus of claim 39, wherein the PUR facility is docked
to each of the half-molds of the outer platens and includes two
injection units and two mixing heads docked to the half-molds of
the outer platens in one-to-one correspondence.
47. The apparatus of claim 38, wherein half-molds of one of the
parting planes are constructed for the production of a right part
of a pair of plastic molded parts, and half-molds of the other
parting plane are constructed for the production of a left part of
the pair of plastic molded parts.
48. The apparatus of claim 38, wherein half-molds of one of the
parting planes are constructed for the production of a main
component, and half-molds of the other parting plane are
constructed for the production of at least one accessory
component.
49. The apparatus of claim 38, further comprising a safety device
adapted for actuation by an operator, and a safety area monitored
by light barriers, wherein a movement of a machine part can be
blocked and released depending on the safety device and the safety
area.
50. The apparatus of claim 49, wherein the machine part is the
middle platen.
51. The apparatus of claim 38, further comprising at least one
dummy mold provided in one of the parting planes.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of prior filed co-pending
PCT International Application Number PCT/EP2007/053264, filed Apr.
3, 2007, which designated the United States and has been published,
but not in English, as International Publication Number WO
2007/113305, and on which priority is claimed under 35 U.S.C.
.sctn. 120, and which claims priority of German Patent Application,
Serial Number 10 2006 016 200.5, filed Apr. 6, 2006, pursuant to 35
U.S.C. .sctn. 119(a)-(d), the contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an apparatus and method for
manufacturing multi-component plastic molded parts.
[0003] Typically, in a first cycle of the manufacturing process of
multi-component plastic molded parts, a preform is made from a
first component in a first cavity. Subsequently, the second
component is molded onto the preform in a second cavity. The
individual components can be made of different thermoplastics and
may have different colors. Certain components may also be provided
with filler material. Instead of thermoplastic components,
polyurethane (PUR) components can be provided. It is also known to
manufacture multi-component plastic molded parts having a
thermoplastic component and a PUR component.
[0004] German patent DE 196 50 854 discloses a method and an
apparatus for manufacturing multi-component plastic molded parts
using rotary table techniques. An injection-molded plastic part is
hereby coated with at least one layer of a 2-component thermoset.
Both components are successively molded in the same mold in a
cycle-synchronous manner. A base plate is hereby used which carries
two identical half-molds side-by-side. The base plate is supported
for rotation about a horizontal and longitudinal machine axis.
Female molds of an injection molding machine and a RIM apparatus
are arranged opposite the half-molds. After the injecting molding
machine injects thermoplastic material, the base plate is rotated
by 180.degree. about the horizontal and longitudinal machine axis.
In the next cycle, a new thermoplastic part is molded and the
thermoplastic part of the first cycle is coated with the
2-component thermoset.
[0005] The article "Hochwertige Premiumoberflachen aus
Spritzgie.beta.- und Reaktionstechnik", [High-Quality Premium
Surfaces Made by Injection-Molding and Reaction Techniques],
describes on pages 180-182 in the 10/2004 edition of the magazine
"Kunststoffe" [Plastics] another method for manufacturing
multi-component plastic molded parts from a first thermoplastic
component and a second PUR component. A station for injecting the
thermoplastic material is provided on the fixed side of a clamping
unit of a known injection molding machine. On the movable side, a
mixing head of a RIM apparatus (RIM: Reaction Injection Molding)
for the PUR component is docked to the half-mold that is arranged
there. RIM apparatuses are known and essentially include conveying
and metering devices for individual chemicals to be processed, such
as polyol, polyisocyanate, and possible additives, such as dyes,
foaming agents, etc. A sliding table for the fixed half-mold is
provided at the fixed side of the clamping unit in order to move
the fixed half-mold from the position "injection molding" to the
position "PUR molding", and vice versa. In the mold position
"injection molding", a carrier such as a carrier made of polyamide
plastics is pre-molded. At the end of the cooling period, the mold
opens and the sliding table moves to the position "PUR molding".
After the mold closes, the PUR molding skin is injected into the
enlarged cavity via the mixing head that is connected with the RIM
mixing and metering unit.
[0006] It is further known in the related art to produce
multi-component plastic molded parts using so-called reversing
plate techniques (Johnnaber/Michaeli, Handbuch Spritzgie.beta.en,
[Handbook Injection Molding] 2001, ISBN 3-446-15632-1, Picture 6.80
on page 508). A middle platen, often called a reversing plate, is
hereby rotatably supported between two outer platens. After the
preform is produced in the first parting plane, the middle platen
transports the preform to the second parting plane. There, the
second component is molded onto the preform.
[0007] WO 03/013824 discloses manufacturing of multi-component
plastic molded parts from a thermoplastic carrier and a PUR molding
skin using the reversing plate techniques. A machine frame movably
supports two outer platens. A supporting frame is mounted on the
machine bed between the two outer platens. In the machine bed, a
middle platen is supported for rotation about a vertical rotation
axis. The middle platen can be plate-shaped and receive two
half-molds. Alternatively, the middle platen can be cube-shaped so
as to receive four half-molds. A suitable
drive-and-locking-assembly can move the outer platens towards and
away from the middle platen and lock the platens. In order to
produce a multi-component molded plastic part from a thermoplastic
base component and a PUR molding skin, one of the outer platens can
be coupled with an injection unit for the thermoplastic base
component, and the other outer platen can be coupled with a RIM
apparatus. Handling robots, such as a processing robot and a
removal robot, can be provided to the side of the clamping unit.
For example, the processing robot can treat the surface of the base
component. In a first cycle, the base component is made of
thermoplastic material and is injection-molded on the side of the
injection unit. After the required cooling period, the clamping
unit is opened and the just molded base component is
surface-treated. The platen is rotated by 180.degree., and the
half-molds are closed again. In the subsequent cycle, a new
thermoplastic base component is molded on the side of the injection
unit, whereas, on the opposite side, a PUR reaction mixture is
injected into the mold via a mixing head and a PUR skin is formed
on the surface of the base component.
[0008] Common to the prior art described above is the production of
a preform in the one parting plane and molding of the second
component onto the preform in the other parting plane while a new
preform is produced in the first parting plane at the same
time.
[0009] It would therefore be desirable and advantageous to provide
a method and an apparatus to obviate prior art shortcomings and to
increase productivity in producing multi-component molded plastic
parts.
SUMMARY OF THE INVENTION
[0010] According to one aspect of the present invention, a method
of making multi-component plastic molded parts, using an apparatus
which includes two outer platens with outer first half-molds, and a
middle platen with middle second half-molds interacting with the
first half-molds such as to define cavities in two parting planes
for injection of a plastic melt and/or a PUR mixture, includes the
steps of allowing one of the first and second half-molds to move in
increments in relation to the other one of the first and second
half-molds to thereby form different cavities in two parting planes
from cycle to cycle, producing in a first cycle preforms in the
cavities respectively formed in the two parting planes between
respective ones of the first and second half-molds, holding the
preforms in one of the first and second half-molds as the other one
of the first and second half-molds moves in increments and
injecting further components into the cavities formed in the two
parting planes from cycle to cycle, and allowing from cycle to
cycle to execute a pretreatment or another process step in free
ones of the first and second half-molds.
[0011] According to another aspect of the present invention, an
apparatus for making multi-component plastic molded parts includes
two outer platens having outer half-molds, a middle platen
positioned between the outer platens, a clamping unit for closing
and locking four of the half-molds of the outer platens and the
middle platen at one time to thereby define two parting planes,
wherein the middle platen carries at least two of a first type of
half-molds that are different from each other and at least two of a
second type of half-molds that are different from each other so as
to successively form in the parting planes with the half-molds of
the outer platens different cavities while leaving free half-molds
for allowing pretreatment or a further process step, and wherein
the outer half-molds are constructed for holding molded parts.
[0012] According to yet another aspect of the present invention, an
apparatus for making multi-component plastic molded parts includes
two outer platens, each having mounted thereon a plurality of
half-molds, a middle platen positioned between the outer platens, a
clamping unit for closing and locking four of the half-molds of the
outer platens and the middle platen at one time to thereby define
two parting planes, wherein the middle platen has a plurality of
mold halves which are constructed to hold molded parts, wherein the
outer platens move in increments in relation to the middle platen
to thereby form, from cycle to cycle, different cavities in the two
parting planes and leaving free half-molds for allowing
pretreatment or a further process step.
[0013] The present invention resolves prior art shortcomings by
allowing several production steps to be successively executed in
both parting planes. This causes an increase in the cycle period.
Still, as two molded plastic parts are produced in each cycle, the
cycle period per molded part is less than when applying reversing
plate techniques. Depending on the application, it is possible to
produce, for example, in a first cycle thermoplastic preforms and,
in a second cycle, the thermoplastic preforms may be flooded with a
PUR component. Alternatively, the second thermoplastic component
may be molded onto the preform. Also, the preform may be produced
from a first PUR mixture and subsequently flooded with a second PUR
mixture. Additional, different cavities may be formed and
additional components may be added in further cycles. Additional
thermoplastic components can be molded and/or additional PUR
mixtures may be provided for flooding purposes.
[0014] Various pretreatments in the free half-molds of the middle
platen may be made during the production process of the preforms
and/or during the flooding or molding onto the preforms.
[0015] The processing of PUR mixtures oftentimes involves the use
of so-called mold release agents to avoid adhesion of the PUR
component in the half-mold. A mold release agent may be added into
the free PUR half-mold or into the free PUR half-molds, for example
via a spraying process. Furthermore, there is sufficient time for
the mold release agent to vent, without causing an increase in the
cycle period. Also, the mold release agent may be vented in a
targeted manner, e.g., by using air to blow the PUR half-mold
clear. Alternatively, PUR residues may be removed by cleaning the
free half-molds, e.g., by means of rotating brushes or by means of
a plasma process, etc.
[0016] Further, the PUR half-molds may be dyed before the PUR
addition. The dye bonds with the subsequently introduced PUR
material. In this manner, coated components can be produced in the
mold (also known as In Mold Coating (IMC) process). In accordance
with an exemplary method of the present invention, varnish may be
added into the free PUR half-mold for an In Mold Coating process
while, in a first cycle, a plastic base component is molded. In the
second cycle, PUR material is flooded between the base component
and the coated PUR half-mold. In this manner, an additional surface
finish (coat of varnish) may be realized cycle-synchronously with a
2-component process.
[0017] Furthermore, inserts and/or decoration materials such as
fabrics, foils, etc. may be inserted and affixed for the subsequent
processes. A PUR coating may then be introduced between the insert
(e.g., a foil) and the plastic carrier. It is hereby advantageous
that the PUR material build up only a low internal mold pressure so
as to be prevented from damaging the insert. This method is of
particular advantage when sensitive decoration materials and
varnished foils are involved. In addition, because of the insert,
there is no need to add a mold release agent for the PUR half-mold.
It is also possible to position the inserts only on areas of the
surface of the PUR half-mold. This allows for production of a
surface comprised of the insert material and the inserted PUR
material.
[0018] The present invention is also advantageous with respect to
producing a pair of plastic molded parts, comprised of a right part
and a left part. Such a pair may be produced in each cycle if the
right part is produced in the one parting plane and the left part
is produced in the other parting plane. This can be done
simultaneously and in the same cycle.
[0019] According to another feature of the present invention, the
middle platen may have a prism-shaped configuration with more than
four mold platen areas. For example, the middle platen may be
hexagonal or octagonal with six or eight mold platen areas,
respectively.
[0020] Suitable combinations of injection units and PUR mixing
heads are provided at the outer platens and/or the outer
half-molds, depending on the application.
[0021] The production of multi-component plastic molded parts from
a thermoplastic base component that is to be flooded with a PUR
component, may involve the provision of known injection units on
the outer platens and their docking to the outer half-molds, while
the mixing heads for flooding with a PUR mixture may be docked
laterally at the outer half-molds, for example in an "L" position
with respect to the respective injection unit or in a vertical
position. The mixing heads may be securely mounted on the
half-molds or, using suitable robots, may be docked onto the
half-molds, for example, only for the time period of flooding the
preform with the PUR mixture. A single PUR metering facility may
supply the PUR mixture to multiple PUR mixing heads. Of course, it
is also conceivable to provide each mixing head with its own PUR
metering facility.
[0022] During the manufacturing process of multi-component plastic
molded parts from multiple thermoplastic components, further
injection units may be provided in an L-position, a piggyback
position, or a vertical position, in addition to the injection
units at the outer platens.
[0023] A suction or exhaust device may be provided above the area
of the free half-molds of the middle platen and/or the outer
platens.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and/or other aspects and advantages of the present
invention will become apparent and more readily appreciated from
the following description of the exemplary embodiments, taken in
conjunction with the accompanying drawings of which:
[0025] FIG. 1 shows a perspective view of an injection molding
machine in accordance with an exemplary embodiment of the present
invention;
[0026] FIG. 2 shows a perspective top view of a module frame of the
injection molding machine of FIG. 1;
[0027] FIG. 3 shows a sectional view of a turntable or rotary table
of the module frame illustrated in FIG. 2;
[0028] FIG. 4 is a schematic illustration of a starting position of
a clamping unit, with confronting half-molds in open position;
[0029] FIG. 5 is a schematic illustration of the clamping unit in
closed position, with the confronting half-molds being closed;
[0030] FIG. 6 is a schematic illustration of an opening movement of
the clamping unit;
[0031] FIG. 7 is a schematic illustration of a counterclockwise
rotation of a middle platen of the injection molding machine of
FIG. 1 to confront different half-molds;
[0032] FIG. 8 is a schematic illustration of the clamping unit in
closed position, with the confronting half-molds of FIG. 7 being
closed and locked;
[0033] FIG. 9 is a schematic illustration of removal of different
finished components from the half-molds;
[0034] FIG. 10 is a schematic illustration of a clockwise rotation
of the middle platen to confront different half-molds;
[0035] FIG. 11 is a schematic illustration of a pretreatment at
free half-molds;
[0036] FIG. 12 is a schematic illustration of one parting plane
remaining unused;
[0037] FIG. 13 is another schematic illustration of one parting
plane being unused;
[0038] FIG. 14 shows a schematic illustration of an apparatus
according to the present invention, having incorporated a safety
device;
[0039] FIG. 15 shows a schematic illustration of a variation of a
rotatable middle platen;
[0040] FIG. 16 shows a schematic illustration of an apparatus
according to the present invention, having a linearly movable
middle platen; and
[0041] FIG. 17 shows a schematic illustration of an apparatus
according to the present invention, having a fixed middle platen
and outer sliding tables.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0042] Throughout all the figures, same or corresponding elements
are generally indicated by same reference numerals. These depicted
embodiments are to be understood as illustrative of the invention
and not as limiting in any way. It should also be understood that
the drawings are not necessarily to scale and that the embodiments
are sometimes illustrated by graphic symbols, phantom lines,
diagrammatic representations and fragmentary views. In certain
instances, details which are not necessary for an understanding of
the present invention or which render other details difficult to
perceive may have been omitted.
[0043] Turning now to the drawings, and in particular to FIG. 1,
there is shown an injection molding machine 1 having a machine bed
35, a fixed platen 2, a movable platen 4, and a cube-shaped middle
platen 6 between the platens 2, 4. The platens 2, 4 support
half-molds 3, 5, respectively, which, together with half-molds of
the platen 6, form cavities. The movable platen 4 is moved towards
or away from the platen 2 via tie-bars 8 that are extended through
the fixed platen 2. Also shown is a drive 10 to move the platen 4,
and injection units 7, 9. The injection unit 7 is supported on a
frame 11 which is mounted to the movable platen 4, whereas the
injection unit 9 is supported on the machine bed 35. A first PUR
mixing head 12 is docked to the movable half-mold 5 and connected
to a first PUR metering facility 13. A second PUR mixing head 14 is
docked to the fixed half-mold 3 and connected to a second PUR
metering facility. The entire assembly comprised of the drive 10
and the platens 2, 4, 6 is supported on a module frame 20, which,
in turn, is mounted on the machine bed 35 of the injection molding
machine.
[0044] FIG. 2 shows a perspective top view of details of the module
frame 20, and FIG. 3 shows a sectional view of a turntable 36 in
the module frame 20. The module frame 20 supports a base plate 26
for movement in linear guides 22. The base plate 26 may be moved
hereby in the longitudinal direction of the machine via hydraulic
cylinder 24 or spindle drives or in some similar manner. The base
plate 26 supports the turntable 36, which is rotatably supported on
the base plate 26 via suitable bearings. The upper side of the
module frame 20 has sliding guides 28 for the movable platen 4. A
strut 30 receives the fixed platen 2. Struts 32, 34 close the
module frame 20 to the outside and may, for example, support the
plate of the drive. The rotatably supported turntable 36 may be
driven, for example, via a gear ring and an intermeshing bevel that
meshes with the gear ring, as is known in international publication
WO 01/10624 A1.
[0045] Turning now to FIGS. 4 to 10 which show schematic
illustrations of the process sequence.
[0046] FIG. 4 shows a starting situation at the beginning of a
cycle, in which the clamping unit of the injection molding machine
is open. Subsequently, the clamping unit is closed by a closing
movement, as indicated by the arrows, and then locked. This
situation is shown in FIG. 5. The half-molds A1 and A2 now form a
first cavity A1+A2 in the first parting plane (parting plane A) for
producing a preform of the component A. Likewise, the half-molds B1
and B2 form a first cavity B1+B2 in the second parting plane
(parting plane B) for producing a preform of the component B. By
means of the injection units 7, 9, thermoplastic melt is injected
into the thus-formed cavities, and preforms for the components A
and B are produced. Simultaneously, a pretreatment may be performed
in the free half-molds A3 and B3 via robots 16 and 17 and their
gripper and pretreatment units 18, 19. For example, a mold release
agent may be sprayed onto the surfaces of the half-molds A3,
B3.
[0047] In the next step, the clamping unit is opened by an opening
movement (FIG. 6), with the preforms remaining attached to the
outer half-molds A1, B1. Subsequently, the middle platen 6 is
rotated by 90.degree., counterclockwise, as shown in FIG. 7, or
clockwise, as shown in FIG. 10, and the clamping unit is closed and
locked again, resulting in a situation as shown in FIG. 8. The
half-molds A3, A1 and the half-molds B3, B1 now form new cavities,
respectively, in which the thermoplastic preforms are situated. By
means of the PUR mixing heads 12, 14, the thermoplastic preforms
can now be flooded with a PUR molding skin. After the reaction time
for the PUR reaction lapses, the clamping unit can be opened and
the finished components A, B can be removed from the half-molds A1,
B1. This is shown in FIG. 9, which also schematically shows that
the components A and B are different. For example, the A component
may be the left part and the B component may be a right part of a
pair of plastic molded parts, such as the left and right door
lining of a car door. Subsequently, the middle platen 6 is rotated
back by 90.degree. and the clamping unit assumes its starting
position again, as shown in FIG. 4. A new cycle may now begin.
[0048] A suction device may be arranged outside the clamping unit
above the lateral area of the half-molds A3, B3 in FIG. 4. This
ensures that gases produced by the mold release agent gases and,
optionally, varnish are exhausted to comply with safety guidelines,
when the half-molds A3, B3 are used PUR half-molds.
[0049] It is not necessary that both components A and B be removed
simultaneously. Optionally, only the parting plane B may be opened,
and the parting plane A may be kept closed. This may be necessary
if the PUR mixtures in the two parting planes A and B have
different reaction times and/or if the thermoplastic components
require different cooling periods. In this manner, the two
components A and B may be removed by the same robot, which is
successively moved into the parting planes A, B to the half-molds
A1 and B1.
[0050] Instead of the pretreatment described above, other
pretreatments or process steps may be performed at the free
half-molds, depending on the application. For example, the free
half-molds may be cleaned. In PUR processing, it is repeatedly
necessary to clean the PUR half-molds, since PUR processing results
in deposits on the mold surface. Mold areas or mold-halves may be
cyclically cleaned using a plasma process, for example. It is also
possible to apply a varnish for an In Mold Coating process in this
cycle. It is also possible to place inserts or decoration materials
such as fabrics or foils in the free half-molds and to secure them
there. The finished component then comprises the two plastic
components and the insert or the decoration material.
[0051] In the event, the second component does not involve a PUR
mixture but involves an additional thermoplastic component to be
molded on, additional injection units may be provided in a known
manner in an L-position, a piggyback position or a vertical
arrangement on the two platens.
[0052] Using the method and apparatus according to the invention,
only three mold-halves per component are needed. By contrast, in
the standard 2-component method using the above-described reversing
plate techniques, four mold-halves per component are needed. Based
on a cycle period of, e.g., 60-70 seconds for a finished component
on a turntable-type injection molding machine or a reversing plate
injection molding machine, a cycle period of 90-100 seconds is
needed for producing the same component using the method according
to the invention. However, two components A and B are produced in
one cycle, resulting in a cycle period of about 45-50 seconds per
component. This leads to a relatively significant cycle period
advantage.
[0053] In addition, using the injection molding machine according
to the invention, two different components may be produced (left
component and right component), whereas, conventionally, two
machines are necessary. Only one mold set having three half-molds
per component is needed. In a standard reversing plate application,
at least four half-molds are needed. As a result, the mold cost per
component is significantly minimized.
[0054] Removal devices may be mounted on the fixed and/or the
movable platen. It is further possible to mount a single removal
device, e.g., a 6-axis-robot, on the middle platen. In this manner,
one removal device can be used for both parting planes A and B.
[0055] FIG. 11 shows schematically the presence of a heat
pretreatment at the free half-molds A2, B2. For this purpose, the
two laterally positioned robots 16, 17 have radiant heaters 35, 36
by means of which heating fields 37, 38 can be generated. The
radiant heaters 35, 36 may perform a pretreatment of the entire
areas or of partial areas of the free half-molds A2, A3, B2 and B3,
while, simultaneously, an injection molding process and/or a PUR
molding process is performed in the respectively closed half-molds.
Particularly when a thermoplastic preform is flooded with a PUR
mixture, preheating of the entire areas or of partial areas of the
PUR half-molds A3, B3 is advantageous because the PUR reaction may
then be accelerated and improved PUR surfaces may be realized.
During the reaction time, the PUR half-mold cools down again to a
temperature that is preset by a medium for maintaining a
temperature so as to carry off the reaction heat and to prevent the
thermoplastic preform from excessively heating up.
[0056] FIGS. 12 and 13 show exemplary embodiments of the invention
wherein one parting plane remains free. According to FIG. 12, a
dummy mold 39 (B1D) is mounted on the fixed platen 2 in the parting
plane of the half-molds B. The half-molds B2, B3 are not needed.
According to in FIG. 13, dummy molds 40 (B2D) and 41 (B3D) are
mounted on the middle platen 6. The half-mold B1 is not needed.
However, it is also possible to replace all three half-molds B1, B2
and B3 with respective dummy half-molds B1D, B2D, and B3D.
Typically, however, it is sufficient to provide only one dummy
half-mold B1D instead of the three half-molds B1, B2, and B3. By
using dummy molds B1D, B2D and/or B3D, the working plane may be
continued to be operated with the A-molds and, simultaneously, the
B-molds outside the injection molding machine may be examined or
processed, e.g., to correct surface defects. The dummy molds serve
as place holders for the actual B-molds.
[0057] FIG. 14 shows an exemplary embodiment of the invention
having a safety device. The apparatus according to the invention is
surrounded by a safety fence 43 on the operator side, and a safety
fence 42 opposite to the operator side of the apparatus. The safety
fences 42, 43 include safety doors 44, 45. The two safety fences
abut at positions 46, 47 and may be connected with each other there
so as to form a closed safety area. Instead of the two safety
fences 43, 44, only one safety fence may be provided that has one
or more safety doors. Parts of the injection molding machine may
protrude from the safety fence where the safety fences abut
(positions 46, 47), for example parts of the respective
plasticizing units. Furthermore, additional safety measures may be
provided. For example, light barriers 48, 49 may be provided, which
substantially include a light source 50 and a receiver or detector
51, and which are connected to a control unit for the safety
measures via wires (not shown). Also, a safety assembly 52 may be
provided, for example two switches 52a, 52b arranged at a certain
distance from each other and which only generate a release signal
to operate the machine if they are actuated simultaneously. The
distance of the two switches 52a, 52b is chosen such that the
operator may actuate the switches 52a, 52b simultaneously only with
spread arms.
[0058] Instead of the platen 6 having two half-molds per parting
plane (A2, A3 or B2, B3), more than two half-molds per parting
plane may be provided on the middle platen 6, depending on how many
components are to be attached in the subsequent cycles to the
preforms produced in the first cycle. FIG. 15 shows schematically
an exemplary embodiment of a rotatable middle platen 60, wherein
more than four half-molds per parting plane are provided, namely
A2, A3, A4 and A5 for the unillustrated half-mold A1, and B2, B3,
B4 and B5 for the unillustrated half-mold B1.
[0059] FIG. 16 shows schematically an exemplary embodiment of the
present invention having a linearly movable middle platen 61 that
has two parallel platen areas, e.g., in the form of a rectangular
mold mounting plate. The half-molds A2, A3, . . . B2, B3, . . . may
be affixed on both sides of this middle platen and may engage with
the outer half-molds A1 and B1 so as to form different cavities
from cycle to cycle. In FIG. 16, the middle platen 61 is fixed with
respect to the longitudinal direction of the machine, whereas the
outer platens 62 and 63 with the outer half-molds A1 and B1 may be
moved in the longitudinal direction of the machine. The middle
platen 61 is movable perpendicularly to the longitudinal axis of
the machine, e.g., horizontally or vertically, so that, from cycle
to cycle, the half-molds A2, A3 . . . and B2, B3, . . . and the
outer half-molds A1 and B2 may be brought together. It is also
possible to provide a fixed outer platen and a movable outer
platen, in which case the middle platen 61 is movable in the
longitudinal direction of the machine.
[0060] FIG. 17 shows schematically another exemplary embodiment of
the present invention, wherein the half-molds A1, B1 are mounted on
a fixed middle platen 66, and wherein the additional half-molds A2,
A3, . . . and B2, B3, . . . are mounted on outer sliding tables 64
and 65. The outer sliding tables 64 and 65, in turn, are movably
mounted to the outer platens 62 and 63 and may be moved together
with the outer platens 62 and 63. However, it is also possible to
provide a fixed outer platen and a movable outer platen, in which
case the middle platen 66 is movable in the longitudinal direction
of the machine.
[0061] A suitable apparatus thus includes two outer platens having
outer half-molds and a middle platen having intermediate or middle
half-molds. Further, provided is a clamping unit for closing and
locking four half-molds, wherein two parting planes are formed. The
half-molds are hereby arranged in such a manner that, from cycle to
cycle, successively different cavities are simultaneously formed in
both parting planes. In the one parting plane, the A half-molds
(A1, A2, A3, . . . ) are brought together, and in the other parting
plane, the B half-molds (B1, B2, B3, . . . ) are brought together,
with the A1 half-mold being brought together in increments with the
other A half-molds, and with the B1 half-mold being brought
together in increments with the other B half-molds. In this manner,
successively different cavities may be formed from cycle to cycle
in the two parting planes. In the one parting plane, the cavities
A1+A2, A1+A3, A1+A4, . . . are formed, and, in the other parting
plane, the cavities B1+B2, B1+B3, B1+B4, . . . are formed. The A
and B half-molds may be configured so as to produce identical or
different molded parts. In the latter case, a right part and a left
part of a pair of molded parts may be involved, for example, such
as parts of a door lining of an automobile. Furthermore, injection
units and/or PUR facilities may be provided which are docked onto
or can be docked onto the platens and/or the half-molds.
[0062] The middle platen 6 may have at least two A half-molds (A2,
A3, . . . ) that are different from each other and at least two B
half-molds (B2, B3, . . . ) that are different from each other. The
outer half-molds A1 and B1 are mounted on the outer platens 2, 4,
which can be embodied as classic mold platens, for example. In the
two parting planes, successively different cavities may be formed
from cycle to cycle: A1+A2, A1+A3, . . . in the one parting plane
and B1+B2, B1+B3, . . . in the other parting plane. The half-molds
are constructed in such a manner that they can hold the preforms in
them. The middle platen 6 may be rotatable. The middle platen 6 may
be cube-shaped or prism-shaped, and rotatable about a vertical or
horizontal axis so that the different cavities may be formed from
cycle to cycle in the two parting planes.
[0063] As an alternative, the middle platen may be plate-shaped or
similarly shaped and includes two parallel platen areas, with the A
half-molds (A2, A3, . . . ) relating to or assigned to the first A
half-mold (A1) being arranged on the one platen area, and the other
B half-molds (B2, B3, . . . ) relating to or assigned to the first
B half-mold (B1) being arranged on the other platen area. The
middle platen 6 moves vertically with respect to the longitudinal
axis of the machine, from cycle to cycle, so that, from cycle to
cycle, different cavities can be formed in the two parting
planes.
[0064] As a further alternative, the functions of the middle platen
6 and the outer platen 2, 4 can also be reversed. Accordingly, the
first A half-mold A1 and the first B half-mold B1 are arranged on
the middle platen 6, whereas the other A half-molds (A2, A3, . . .
) are arranged on one of the outer platens 2, 4 and the other B
half-molds (B2, B3, . . . ) are arranged on the other one of the
outer platens 2, 4. The two outer platens 2, 4 can be linearly
moved in increments and/or rotated about a horizontal axis in
increments so that different cavities are formed in both parting
planes, from cycle to cycle. For example, the platens may be
sliding tables or turntables which, in turn, may be mounted on the
outer platens.
[0065] A suitable apparatus includes a fixed platen and a movable
platen (the outer platens) arranged on a machine bed, between which
the middle platen is moved on a sliding table in the longitudinal
direction of the machine and between which the middle platen is
pivotable around a vertical axis. The middle platen is cube-shaped
and carries four half-molds (A2, A3, B2, B3). Two adjacent ones of
these half-molds (A2, A3 or B2, B3) relate to or are assigned to an
outer platen to form cavities of different size. The outer
half-molds are shaped in such a manner that the preform remains
therein.
[0066] It is also possible to provide two moving outer platens on a
machine bed, with the middle platen being fixedly connected with
the machine bed between the outer platens and rotatable about a
vertical axis. The middle platen is cube-shaped and carries four
half-molds (A2, A3, B2, B3). Two adjacent ones of these half-molds
(A2, A3 or B2, B3) relate to or are assigned to an outer
platen.
[0067] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit of the present
invention. The embodiments were chosen and described in order to
best explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
* * * * *