U.S. patent application number 10/803522 was filed with the patent office on 2005-01-27 for rotary injection molding apparatus and method for use.
Invention is credited to Boyd, Kathleen C., Boyd, Thomas J..
Application Number | 20050019443 10/803522 |
Document ID | / |
Family ID | 33029980 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050019443 |
Kind Code |
A1 |
Boyd, Kathleen C. ; et
al. |
January 27, 2005 |
Rotary injection molding apparatus and method for use
Abstract
A rotary injection molding apparatus and method for
manufacturing products containing elastomeric material within
multi-section single cavity molds. The apparatus includes a modular
frame supporting an injection molding operation station having an
injector assembly with a pressure sensitive nozzle assembly. The
injector assembly is engaged with an extruder assembly at a check
valve assembly. A mold servicer assembly is provided for assembly
and disassembly of multi-section single cavity molds. A robotic arm
assembly is supported on the modular frame and positioned for
inserting and removing products or product components from
disassembled molds. Finally; a rotating table is provided on the
frame which has a plurality of work station positions supporting
clamping assemblies for clamping single cavity molds around the
periphery of the rotating table.
Inventors: |
Boyd, Kathleen C.; (Akron,
OH) ; Boyd, Thomas J.; (Akron, OH) |
Correspondence
Address: |
JEANNE E. LONGMUIR
2836 CORYDON ROAD
CLEVELAND HEIGHTS
OH
44118
US
|
Family ID: |
33029980 |
Appl. No.: |
10/803522 |
Filed: |
March 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60455275 |
Mar 17, 2003 |
|
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Current U.S.
Class: |
425/556 ;
425/139; 425/576 |
Current CPC
Class: |
B29C 45/42 20130101;
B29C 45/54 20130101; B29C 45/06 20130101; B29K 2021/00 20130101;
B29C 2045/425 20130101; B29C 45/14008 20130101 |
Class at
Publication: |
425/556 ;
425/576; 425/139 |
International
Class: |
B29C 045/42 |
Claims
We claim:
1. An injection molding apparatus for manufacturing products
containing elastomeric material within single cavity molds, said
apparatus comprising, a modular frame supporting an injection
molding operation station including an injector assembly having a
pressure sensitive nozzle assembly, the injector assembly engaged
with an extruder assembly at a check valve assembly, and a mold
servicer assembly for assembly and disassembly of single cavity
molds, a robotic assembly positioned for inserting and removing
products or product components from positions within said injection
molding apparatus; and a rotating table having a plurality of
positions along the periphery of the rotating table to move a
single cavity mold into and out of engagement with the injection
molding operation station, each position supporting a clamping
assembly for clamping a single cavity mold.
2. The injection molding apparatus of claim 1 wherein the rotating
table has a substantially circular configuration.
3. The injection molding apparatus of claim 2 wherein operation of
the injector assembly, nozzle assembly, extruder assembly, robotic
assembly, rotating table and clamping assemblies are all computer
controlled by a central programmable controller.
4. The injection molding apparatus of claim 1 wherein the robotic
assembly is positioned at a corner of the modular frame to permit
use of the robotic assembly at one or more adjacent injection
molding systems.
5. The injection molding apparatus of claim 1 wherein the modular
frame includes sidewalls which are aluminum castings.
6. The injection molding apparatus of claim 1 wherein said injector
assembly and extruder assembly are configured to enable injection
pressures sufficient to initiate curing of the product.
7. The injection molding apparatus of claim 1 wherein said mold
servicer assembly includes a bronze central drive cam for improved
wear resistance.
8. A method for manufacturing products containing elastomeric
materials using an injection molding system, comprising the steps
of: disassembling a multi-section single cavity mold at a
disassembly station to reveal a mold cavity and inserting any
inserts to be molded into a manufactured product into the mold
cavity; reassembling the multi-section single cavity mold and
providing the assembled mold to a clamping assembly supported on a
rotating table having a plurality of positions along the periphery
of the rotating table, said clamping assembly maintaining the
single cavity mold under pressure; rotating the rotating table to
move the single cavity mold into engagement with an injection
molding operation station, the station including an injector
assembly having a pressure sensitive nozzle assembly, the injector
assembly engaged with an extruder assembly at a check valve
assembly; positioning the nozzle assembly of the injector assembly
against the single cavity mold and injecting elastomeric material
from the extruder assembly; removing the nozzle assembly from
engagement with the single cavity mold; rotating the single cavity
mold supported within the clamping assembly out of engagement with
the injection molding operation station and around the rotating
table during curing of the product, to the disassembly station; and
disassembling the single cavity mold at the disassembly station and
removing the cured product from the single cavity mold.
9. The method of claim 8 further comprising the step of
synchronizing operations at each of the stations and positions to
provide in-line manufacture or cure of products within each of the
clamping assemblies positioned on the rotating table.
10. The method of claim 8 further comprising the step of removing
the cured product from the injection molding apparatus using a belt
conveyor positioned adjacent the mold disassembly and assembly
position.
11. The method of claim 8 further comprising the step of providing
the cured product to other product finishing operations.
12. The method of claim 9 further comprising the step of
maintaining the single cavity mold under pressure sufficient to
cure the product within the clamping assembly.
13. The method of claim 9 further comprising the step of providing
the product inserts to the cavity of the single cavity mold using a
robotic assembly positioned on a corner of the modular frame.
14. The method of claim 8 wherein curing the product within the
multi-section single cavity mold rotating around the rotating table
following engagement with the injection molding operation station
until the disassembly station is reached ranges from a time of
approximately 80 to 160 seconds.
15. The method of claim 8 wherein the step of rotating the rotating
table provides synchronized movement of and operations on the
multi-section single cavity molds at each of the plurality of
positions along the periphery of the rotating table.
16. The apparatus of claim 1 wherein the injector assembly and the
extruder assembly are supported at an angle of between 20 and 25
degrees with respect to a central axis between sidewalls of the
modular frame.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority from U.S. patent
application Ser. No. 60/455,275 filed Mar. 17, 2003, the entire
subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to invention molding machines
and more specifically to a rotary injection molding apparatus and
method for its use.
[0004] 2. Background of the Related Art
[0005] Injection molding machines are commonly used in the
manufacturing industry for molding elastomeric materials such as
rubber, plastic or combinations of these materials. For example,
current vibration control components for the automotive industry
are produced using large injection press machinery with
multi-cavity molds. Multi-cavity molds produce large amounts of
natural rubber waste from the large runner-system, cavity flash,
and damaged cavities. The time and cost to engineer and manufacture
these intricate molds and their associated tolling is very high.
Product quality and consistency is also compromised due to the
variation in cavity pressures and temperature.
[0006] The multi-cavity mold style of molding also requires
extensive operator intervention, which can lead to operator error
and operator injuries due to the hazards associated with the large,
heavy, hot molds. Automating high-cavity molds is clumsy, expensive
and often unsuccessful. The multi-cavity systems almost always
require secondary finishing operations, which cost the plant time
and money.
[0007] Additionally, in prior art multi-cavity mold systems,
performing tasks such as mold changes for different parts required
the use of heavy lifting equipment. Also, moving the press to
another location is not easily done since many of these large
presses require a large floor pit.
[0008] Prior examples of injection molding machine solutions which
avoid the use of multi-cavity molds are disclosed in U.S. Pat. Nos.
6,604,936 and 5,843,487. The components of prior single mold
injection molding systems typically include a stock supply
assembly, an extruder assembly, an injection assembly, a mold and a
clamping assembly. In a typical molding process, the stock supply
assembly supplies a certain amount of stock material to the
extruder assembly. The extruder assembly processes or plasticizes
the stock material into injection material, and conveys the desired
amount of material to the injection assembly. Upon clamping of the
mold within the clamping assembly under the force necessary for
successful molding, the injection assembly injects the injection
material into a mold cavity within the mold. When a metal insert or
other mold component is required in the molding procedure using an
injection molding machine, sections or portions of the mold must
initially be separated and an unfinished component, insert or work
piece loaded into one of the mold sections. The mold sections are
then assembled to form the internal mold cavity.
[0009] Once the mold cavity is formed, the mold is clamped under
the necessary force to hold the unfinished inserts, components or
work pieces in position during operation of the injection assembly,
which injects the elastomeric molding material into the mold
cavity. The mold sections are then opened or removed and the molded
product having the previously unfinished, now molded part and
insert or joined work pieces, are unloaded from the mold cavity.
However, none of these prior solutions provides the advantages of a
rotary injection molding system.
SUMMARY OF THE INVENTION
[0010] The present invention provides a safe, simple and more
efficient injection molding apparatus and method for injection
molding elastomeric products by using multiple single cavity molds
which are rotated into and out of operation on a rotating table. By
using single cavity molds, all the disadvantages of the
multi-cavity system method are eliminated or reduced.
[0011] Advantages of the use of single cavity molds over
multi-cavity mold systems include that they have little or no
runner system, so natural waste is dramatically reduced. Cavity
flash can be minimized or eliminated by accurate and precise
control of cavity fill pressures and concentrated clamp forces at
the surfaces adjacent to the cavity. Secondary trimming operations
for flash removal, or other finishing operations, may also be
eliminated or reduced. Single cavity molds can be designed and
fabricated in a fraction of the time it takes to design and
manufacture a multi-cavity mold. Also, changes to the single cavity
molds can be implemented rapidly, leading to shorter
product-to-market time. The smaller mold size also allows for easy
mold change capability, as well as easier and less dangerous
handling by operators.
[0012] While prior single cavity systems of injection molding have
been used, the present application provides numerous improvements
over such prior systems. The automated rotary injection apparatus
of the present application enables increased efficiency due to the
use of an increased number of mold stations supporting individual,
removable, multi-section, single cavity molds within individual
clamping assemblies on a rotating table. Easy integration of
additional upstream and downstream operations is also possible,
such as the application of a swager into the press. The modularity
of the present apparatus enables the assembly of a completed
machine having multiple components or modules in one system which
may be readily shipped in a manner which is ready for use right off
the truck.
[0013] The present injection molding apparatus is provided within a
modular frame which supports a fixed injection molding operation
station which includes an extruder assembly, and an injection
assembly with a nozzle assembly, which are interconnected at a
check valve assembly. Elastomeric stock material is supplied to the
extruder assembly by a supply assembly. A mold servicer assembly is
provided at a disassembly station, adjacent the injection molding
operation station, where the multi-section single cavity molds are
disassembled and reassembled by the mold servicer assembly prior to
engagement with the injection molding operation station. A robotic
assembly or robot arm is also supported on the modular frame. The
robotic assembly is preferably provided with at least 6 degrees of
freedom and is positioned at a corner of the modular frame to
permit access to the single cavity mold at the disassembly station
as well as to adjacent injection molding systems. Finally, the
modular frame supports a rotating table having a plurality of
stations along its periphery, preferably at least 8 or more
stations. Each station supports a clamping assembly for clamping a
multi-section single cavity mold therein during operations at the
injection molding operation station and thereafter for curing as
the mold moves around the rotating table back to the disassembly
station. As used herein, the term "cure" is intended to include
treatment by the application of heat, pressure, or other material
treatments whereby the molding process is completed and the
manufactured product containing elastomeric materials and any
components attains its finished condition.
[0014] To begin the process of manufacturing a product, the mold
servicer assembly disassembles the multi-section single cavity mold
at the disassembly station. Inserts or other product components are
supplied to the mold cavity by the robotic arm. Such inserts or
components may be supplied to the robotic arm by belt conveyors,
bowl or magazine feeders positioned adjacent the rotary injection
molding apparatus. Alternatively, an operator may inserts
components to be molded prior to the injection operation.
[0015] The mold is then reassembled by the mold servicer assembly
and moved into engagement within a clamping assembly supported on
the rotating table. The rotating table then moves the mold into the
injection molding operation station adjacent the extruder and
injector assemblies, and a pressure sensitive nozzle assembly is
then advanced into engagement with a sprue opening in the mold.
Once the nozzle assembly engages the mold, elastomeric material
previously provided from the extruder assembly to the injector
assembly via the rotary check valve assembly, is then provided to
the mold again via the rotary check valve. Once the material is
injected into the mold, the rotating table advances the mold to
another position, while another mold within a clamping assembly has
also been advanced to the injection molding operation station for
the next successive injection molding operation. Where the rotating
table is provided with 10 stations, additional injection operations
are performed successively upon additional molds until the original
mold returns to the original station and is provided to the mold
servicer assembly for disassembly and removal of the manufactured
product. The robot assembly is preferably used to remove the
manufactured product, to remove waste material from the sprue
opening and runner system, as well as to prepare the mold for the
next molding operation, by inserting any necessary product
components into the mold cavity.
[0016] Following removal of manufactured products and preparation
of the mold for the next molding operation, the mold servicer
assembly reassembles the multi-sections of the single cavity mold,
and the process is repeated as previously described. Manufactured
product may be removed to an adjacent belt conveyor to shipping
containers, or provided manually or via the robot assembly to
additional adjacent processing stations, such as a buffing, oil
dipping or swaging station.
[0017] A control system is provided for automatically controlling
operation of the rotary injection molding apparatus, such as system
and component pressures, speeds, temperatures, cycle times and
injection volumes.
[0018] These and other advantages and features of the invention
will be better understood from the detailed description of an
embodiment of the invention which is described in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a partial, schematic perspective view of the
rotary injection molding apparatus of the present application with
safety panels removed;
[0020] FIG. 2 is a partial, schematic perspective view of the
apparatus of FIG. 1 having safety panels in place, and with a
supply of product components being supplied via a belt
conveyor;
[0021] FIG. 3. is a cut-away partial, schematic view of the
apparatus of the present invention having safety panels removed,
and with optional additional stations shown in the form of a belt
conveyor supplying product components, a swager unit positioned
adjacent the mold servicer assembly, and a take away belt conveyor
for removing completed products from the apparatus;
[0022] FIGS. 4A and 4 B are cut away partial, schematic views of
the injector and extruder assemblies supported on portions of the
modular frame, with FIG. 4A showing the injector assembly in a
raised position and FIG. 4B showing the injector assembly in a
lowered position where the nozzle assembly would engage a mold;
[0023] FIG. 5 is a side view of the assemblies shown in FIG.
4A;
[0024] FIG. 6 is a top view of the assemblies shown in FIG. 5;
[0025] FIG. 7 is a cut away side view of the assemblies taken along
the line 7-7 in FIG. 6;
[0026] FIG. 8 is a partial detail view of the portion circled at
the designation 8 in FIG. 7;
[0027] FIG. 9A is a partial cut away view of the assemblies taken
along the line 9-9 in FIG. 6 and with the rotary check valve shown
in extrude position;
[0028] FIG. 9B is a partial cut away view of the assemblies taken
along the line 9-9 in FIG. 6 with the rotary check valve shown in
inject position;
[0029] FIG. 10 is a partial external perspective view of the
extruder assembly of the apparatus of the present application;
[0030] FIG. 11 is a partial external perspective view of the
injector assembly of the apparatus of the present application;
[0031] FIG. 12A is a partial external perspective rear view of the
rotary check valve assembly, and
[0032] FIG. 12B is a partial external perspective front view of the
rotary check valve assembly;
[0033] FIG. 13 is a cut away view of the rotary check valve
assembly taken along the line 13-13 in FIG. 12A;
[0034] FIG. 14 is a cut away view of the rotary check valve
assembly taken along the line 14-14 in FIG. 12B;
[0035] FIG. 15 is a partial perspective view of the rotary or
rotating table of the present application;
[0036] FIG. 16 is a cut away view of the rotary table taken along
the line 16-16 of FIG. 15;
[0037] FIG. 17 is a schematic front perspective view of a clamping
assembly of the present application which is supported at multiple
stations surrounding the rotary table;
[0038] FIG. 18 is a schematic rear perspective view of a clamping
assembly of the present application;
[0039] FIG. 19 is schematic cut away side view of the robotic
assembly and the mold servicer assembly mounted on a corner of the
modular frame of the rotary injection molding apparatus of the
present application for use at an optional adjacent rotary
injection molding apparatus illustrated schematically;
[0040] FIG. 20A is a schematic partial bottom perspective view of
the robotic assembly illustrated in FIG. 20 and
[0041] FIG. 20B is a schematic partial side view of the robotic
assembly of FIG. 20;
[0042] FIG. 21A is a schematic perspective view of a preferred
embodiment of a multi-section single cavity mold of the type used
in the rotary injection molding apparatus of the present
application;
[0043] FIG. 21B is a partial cut away side view taken along the
line 21B-21B of the mold in FIG. 21A;
[0044] FIG. 22 is a schematic perspective view of the mold servicer
assembly illustrated in FIG. 19 and shown in an open position for
disassembling a mold;
[0045] FIG. 23 is a schematic perspective view of the mold servicer
assembly illustrated in a closed position in which a mold is
supported in an assembled position;
[0046] FIG. 24 is a schematic partial cut away view of the mold
servicer assembly taken along the line 24-24 of FIG. 22;
[0047] FIG. 25 is a schematic partial cut away view of the mold
servicer assembly taken along the line 25-25 of FIG. 23;
[0048] FIG. 26 is a schematic partial cut away view of the mold
servicer assembly taken along the line 26-26 of FIG. 22;
[0049] FIG. 27 is a schematic partial cut away view of the mold
servicer assembly taken along the line 27-27 of FIG. 23;
[0050] FIG. 28 is a schematic partial perspective view of the
robotic gripper assembly illustrated supported on the mold servicer
assembly in FIG. 23;
[0051] FIG. 29 is a partial, schematic perspective front view of
the modular frame supporting partially illustrated elements of the
hydraulic, environmental and electrical control systems of the
present application;
[0052] FIG. 30 is a partial, schematic perspective rear view of the
modular frame supporting partially illustrated elements of the
hydraulic, environmental and electrical control systems of the
present application;
[0053] FIG. 31 is a partial, schematic perspective rear view of the
modular frame supporting partially illustrated elements of FIG. 30,
but with safety panels removed and cabinet doors opened;
[0054] FIG. 32 is a schematic perspective view of a portion of the
assembly control system regulating certain of the environmental,
electrical and valving systems of the present application; and
[0055] FIG. 33 is a schematic cut away side view of the assembly
control system taken along the line 33-33 of FIG. 32.
DETAILED DESCRIPTION OF THE DRAWINGS
[0056] Turning now to the illustrations of the present embodiment,
a multi station rotary injection molding apparatus 10 provides high
production injection molding of manufactured products M. In the
illustrated embodiment, the rotary injection molding apparatus 10
is supported on a modular frame 20 and includes a rotating table 22
having 10 work stations 24 positioned along the periphery of the
rotating table 22. Independent clamp assemblies 28 are supported on
the rotating table for engagement with a single extruder and
injector assembly, also supported on the modular frame 20. In the
preferred embodiment of the apparatus, cure times for manufactured
products M are between approximately 75 to 160 seconds per product,
and preferably approximately 80 seconds per product. With small
multi-section single cavity molds 30, cycle times for movement
between positions or stations may be 20 to 30 seconds.
[0057] All press operations are automatic and controlled by an
Allen Bradley programmable logic controller, such as an SLC 5/05
PLC. Additionally, the apparatus is programmed using Allen Bradley
RS Logix 500 software, as well as a variety of other Allen Bradley
system controllers, for example, for remote scanner modules in
communication with the rotating table (1747-SN), servo controllers
(1398 Ultra AC), drives for motor speed control, IEC style
pushbutton switches, and guard master safety relays and emergency
stop buttons, as well as other conventional controllers all of
which are well known to one of ordinary skill in the art and are
collectively referred to herein as the central control system 54.
Operation of these numerous controller, drive, sensor and switch
components are provided at an operator interface terminal, such as
a Parker Automation CTC PS10 color touch screen 56 which is
illustrated in FIG. 1 on a control arm which enables the terminal
to clear all equipment and secondary equipment.
[0058] Certain of the environmental, electrical and valve systems
are provided within a central cabinet 58 located within the modular
frame 20 as shown in FIGS. 29, 32 and 33. Air intake and exhaust
are provided from the central cabinet via a rotary air union to
provide air cooling for the control components. The improved
cabinet 58 is fully insulated and includes 3 insulated doors upon
which electrical components may be mounted, and which also enable
ready access to the controls for repair and cleaning. Additional
system units, such as the Rexroth hydraulic unit 59 with dual smart
pumps, are also secured to the modular frame, and preferably at
corner locations such that ready access to the units is provided
upon removal of the adjacent doors or safety panels 20f, as shown
in FIG. 29. Likewise, electrical connections are provided adjacent
frame openings and connections are preferably quick disconnect
components to permit quick change out of components.
[0059] In the illustrated embodiments of FIGS. 1 through 7, 15-16
and 29 to 31 elements of the modular frame 20 are illustrated. For
example, the frame supports each of the apparatus components on a
machined base plate 20a and their positions are registered with
respect to each of the other components. Fork lift openings 20b are
provided to enable convenient movement of the apparatus from one
location to another and for shipment. Additional attachment
openings 20c are provided to enable attachment of additional
upstream or downstream processing stations PS of the type
illustrated in FIG. 2, such as intake and take away conveyors,
swaggers, carousels, bowl feeders, quality control vision checks,
as well as other necessary processing options. The open structure
of the modular frame also enables the use of storage drawers 20h of
the type shown in FIG. 29 through 31, which provide ready access to
the electrical systems, temperature and air regulators which may be
supported therein.
[0060] As shown in FIG. 15, additional components, such as a
rotating table platform 20d, are secured to the base plate 20a
using conventional fasteners. Grooves 20e are provided to ensure
proper positioning or registration between the apparatus
components. The rotating table platform grooves 20e are engaged by
frame sidewalls 20g which support additional apparatus components.
The use of the modular frame of the present invention provides the
apparatus with a small plant floor footprint, many space saving
aspects, as well as the ability to surround the apparatus with
safety panels 20f for operator protection.
[0061] The injection molding apparatus modular frame 20 supports a
fixed injection molding operation station 40 which includes an
extruder assembly 46, and an injection assembly 48 with a nozzle
assembly50, which are interconnected at a rotary check valve
assembly 52.
[0062] As show in FIG. 6, the frame side walls 20g supporting the
injector and extruder assemblies are of different thickness. The
side walls are preferably aluminum castings to support the
necessary pressures provided to the mold 30 at the injection
molding operation station 40. Additional strengthening ribs or
cross bracing 20i are provided between the sidewalls to resist
twisting movement and ensure support of the assemblies at the
station 40.
[0063] Elastomeric stock material is supplied to the extruder
assembly through a door adjacent the extruder assembly by a supply
assembly (not illustrated). The extruder assembly is designed with
all bolt fasteners 88 on one end, which extend to enable the use of
larger rods, which improves wear resistance in the internal seals
and permits the use of higher extrusion pressures. The material is
plasticized by the rotating extruder screw 94 using a hydraulic
motor 86. The extruder is provided with a heated jacket to maintain
material temperatures at the preset desired temperature for proper
curing of the material. A precise amount of desired and
predetermined material is then fed through a mechanical rotary
check valve assembly 44 to the injector assembly 48.
[0064] The rotary check valve assembly 44 is also mounted between
cast aluminum sidewalls 20g, which are engaged along mating rails
with the sidewalls of the injection molding operation station as
shown in FIG. 6. A hydraulic unit 90 which rotates the check valve
assembly is likewise located within a cast housing 91 to support
the assembly for high pressure operation. The use of a stronger
housing resists movement of the assembly 44 during operation which
provides more accurate operation. The interior portion of the
sidewalls adjacent the injector assembly is provided with
insulation material 92. When in the position illustrated in FIG.
9A, the rotary check valve 100 provides a material flow path to the
injector assembly 48. When the injection chamber 110 of the
injector assembly is filled to the proper amount, the rotary check
valve 100 is moved to the position shown in FIG. 9B by the
hydraulic unit, and a flow path is provided for the material to be
injected into a mold 30 via a nozzle assembly 50. In the event it
is necessary to remove material from the extruder or injector
assemblies, removal of the bolt 102 from the rotary check valve
assembly 44 enables materials within either assembly to be readily
removed. The rotary check valve 100 is preferably a steel valve
with an Armalloy.RTM. coated bronze sleeve. Additionally, as shown
in FIG. 13, the rotary check valve is maintained within the
assembly 44 by a bolt 102'. By removing the bolt 102' the entire
valve 100 may be readily removed from the assembly. Alternatively,
the opening provided for bolt 102' could be provided with a
temperature sensor or other control device, as the system may
require.
[0065] The central structure of the injector assembly 48 is
preferably illustrated machined of round bar stock 113 with an
opening for providing access to the assembly 48 for cleaning and
changing of worn parts. The assembly includes a heated thermal
jacket 111 to maintain material temperatures. The hydraulic unit
112 and heated jacket 111 are interconnected with the intermediate
bar stock 113 via four tie rods as shown in FIG. 11. FIGS. 9A and
9B illustrate that the injector assembly plunger tip 114 is
provided with a Teflon.RTM. bronze seal, which together with the
injection pressure provided during the injection operation, form
surrounding seals which prevent material from moving backward in
the injection chamber and thereby reduces wear. Additionally a
chamfered opening or lead in 108 is provided into the injection
chamber 110. The combination of the lead in 108 with the aligned
sealed tip functions to keep the plunger aligned and also reduces
plunger tip wear.
[0066] Before injection of the mold 30 with elastomeric material
begins, the mold servicer assembly 42 disassembles the
multi-section single cavity mold 30 at the disassembly station 43.
The mold servicer assembly 42 and disassembly station 43 are shown
in FIG. 19 supported adjacent the injection molding station 40 and
a robotic arm assembly 70.
[0067] The preferred multi-section single cavity mold to be
supplied to the mold servicer assembly 42 is illustrated in FIGS.
21A and 21B. The mold is a three part or section mold with top,
middle and bottom sections 32, 33 and 34, respectively. However,
two, four or more mold sections may be desired. The external
surface of the mold 30 is preferably provided with 1.backslash.4
inch aircraft insulation. A round body design is also preferred.
Each section is provided with mounting structure or rails 60 for
being supported within the mold servicer assembly 42, and a side
rail 6o' is also provided for movement of the middle mold section
33. A sprue opening 38 engages the nozzle assembly 50 during
injection, and the mold material is provided to the mold cavity 62
via sprue channels 36. In the illustrated embodiment the top plate
32 is effectively a removable sprue plate which enables access to
the sprue opening 38 and channel 36 for more reliable removal of
waste sprue material with the top plate 32. Inserts W or other
product components are supplied to the mold cavity 62 by the
robotic arm assembly 70.
[0068] The robotic assembly or robot arm 70 is also supported on
the modular frame 20. The robotic assembly illustrated is an Adept
six axis robot. The robot arm preferably includes 6 degrees of
freedom to provide more versatility of functionality and to reduce
cycle time. The robot arm is supported on the frame 20 by an
aluminum cast plate 72. The plate 72 is provided offset from the
modular frame 20 to allow greater range of motion, and is also
positioned at a corner of the frame 20 to permit optional access to
additional adjacent injection molding systems 10', as shown in FIG.
19. The robot arm 70 may be positioned in either a conventional
configuration, or in an inverted mounting configuration as shown in
the figures. A Robohand quick change robot end 74 is provided for
engagement with product inserts or components W and finished
products M.
[0069] The mold servicer assembly 42 first receives the mold 30 in
an assembled condition when the mold servicer assembly 42 is in a
closed configuration as shown in FIG. 23. In this position the mold
top section 32 is engaged along its mating rails 60 within grooves
or guide bars 81 in an upper mold assembly 76. The mold middle
section 33 is engaged along its mating rails 60 within guide bars
81 in a center mold assembly 77. The mold bottom section 34 is
engaged along its mating rails within guide bars 81 in a lower mold
assembly 78. Each of the upper, center and lower mold assemblies
76, 77, 78 of the mold servicer assembly is provided with a
hydraulic cylinder unit 82 for movement of its respective mold
section. Each of the hydraulic units 82 preferably includes a
Temposonics position sensor to provide true position information to
the system controller 54 and thereby obtain more controlled motion
of the assemblies, such as variable speed. The hydraulic cylinder
units 82 are provided so that they can be individually removed from
the mold servicer assembly 42 while it is fully assembled.
Additionally, each of the guide bars 81 are removable from their
respective assemblies for providing alternative split mold
options.
[0070] Once the mold 30 is positioned within the mold servicer
assembly 44, the hydraulic cylinder units of the upper and lower
assemblies operate to disassemble the mold by vertically moving and
rotate the top and bottom mold sections, respectively, to the
locations shown in FIG. 22. The upper assembly 76 is moved
vertically upward to a position where a sprue picker assembly 120
(shown in FIG. 28) having a Robohand gripper 122 providing several
degrees of freedom of movement, may access a sprue opening 28 in
the mold top section 32 to remove any waste material remaining in
the mold from a prior molding operation. An integrated rotary
mechanism 121 turns with the upper mold assembly 76. To remove any
manufactured products M from the bottom mold section 34 within the
lower mold assembly 78, the assembly may rotate down upon a pin
which would raise the product M within the bottom mold section 34
and enable the robotic arm 70 to readily gain access to the
product.
[0071] The center mold assembly 77 does not rotate but moves
horizontally using the hydraulic unit 82 for an appropriate
distance for any necessary middle mold section 33 adjustments. A
high powered magnet 124 is provided adjacent the guide bars 81 for
maintaining mold sections within the guide plates 81 during
rotating movement of the mold servicer assembly 42. Rotating
movement during the vertical lifting and lowering of the upper and
lower mold assemblies, 75, 78 is assisted with thick wall guide
cams 126 along the central axis of the mold servicer assembly 42.
having
[0072] Once any sprue waste and manufactured products are removed
from the disassembled mold sections 32, 33, 34, the mold sections
may be reassembled by return movement of the mold servicer assembly
42 to the position shown in FIG. 23.
[0073] The assembled mold 30 is pushed out of the center mold
assembly 77 using the horizontal movement of the center mold
assembly 77. The mold 30 is pushed into a clamping assembly 28
which is mounted at a work station 24 on the rotary table 22. The
upper and lower clamping assembly posts 128 are engaged through
spaced openings 129 in the rotary table 22. The posts 128 are
joined on top of the rotary table at an upper bridge 132 and under
the rotary table 22 at a lower bridge 132'. The posts are joined
together adjacent the openings 129 at guide bushings 134. The
mounting of clamping assemblies 28 at each work station 24
surrounding the periphery of the rotating table 22 is best seen in
FIG. 3. The mold 30 is received into an opening 130 in the clamping
assembly 28 which accommodates a mold 30 of approximately 8 inches
in height as illustrated in FIG. 17 and using integrated mold
guides 136. The mold 30 is engaged on the bottom mold section 32
with a bronze wear plate 138. Upper and lower heated platens 140
are adjacent the mold sections, followed by an inch of insulation
material 142 as well as a heater wire cover. A heavy duty hydraulic
cylinder 144 is provided for clamping the mold 30 within the
clamping assembly during the injection operation at the injection
molding operation station 40 and for applying the necessary
clamping pressure during curing of the product M as the mold 30 is
rotated within the clamping assembly 28 around the work stations 24
at the rotary table 22. The rotary table 22 rotates using an Allen
Bradley servo drive motor 146, with an attached gear reducer 148
engaged with gear teeth 150 secured to the bottom of the rotary
table 22.
[0074] Once engaged within the clamping assembly 28 and clamped,
the rotating table 22 then indexes the mold 30 to the injection
molding operation station 40 adjacent the extruder and injector
assemblies 46, 48. Once the nozzle assembly 50 is lowered into
engagement with the sprue opening 38 in the mold, the material is
injected into the mold via the extruder, injector and rotary check
valve assemblies. A supplemental nozzle touch system 51 has been
designed to assist the nozzle assembly 50 so that it may be
retracted back from the heated platen to prevent curing of the
material inside the nozzle assembly, to provide clearance when the
rotary table 22 indexes and to provide access to change out the
nozzle.
[0075] Once the rotary table 22 has indexed the clamped mold to
each of the 10 preferred work stations 24, the mold 30 is returned
to the mold servicer assembly 42 and is disassembled to again
initiate the molding cycle within the mold. It should be understood
that the rotary injection molding apparatus of the present
application enables continuous synchronous molding of the single
cavity molds 30 within each of work stations 24 and the disassembly
station. 43.
[0076] While an exemplary embodiment of the rotary injection
molding apparatus and its method of use having been described with
a degree of particularity, it is the intent that the apparatus
include all modifications and alterations from the disclosed design
falling within the spirit or scope of the appended claims.
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