U.S. patent application number 12/361488 was filed with the patent office on 2010-02-04 for continuous forming system utilizing up to six endless belts.
This patent application is currently assigned to CENTURY-BOARD USA, LLC. Invention is credited to Wade H. Brown, Zachary Taylor.
Application Number | 20100025882 12/361488 |
Document ID | / |
Family ID | 34795183 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100025882 |
Kind Code |
A1 |
Taylor; Zachary ; et
al. |
February 4, 2010 |
CONTINUOUS FORMING SYSTEM UTILIZING UP TO SIX ENDLESS BELTS
Abstract
A system for providing shape and/or surface features to a
moldable material includes, in an exemplary embodiment, at least
two first opposed flat endless belts spaced apart a first distance,
with each having an inner surface and an outer surface. The system
also includes at least two second opposed flat endless belts
disposed substantially orthogonal to the first two opposed endless
belts and spaced apart a second distance. A mold cavity is defined
at least in part by the inner surfaces of the at least two opposed
flat endless belts. The system further includes a drive mechanism
for imparting motion to at least two of the opposed flat endless
belts.
Inventors: |
Taylor; Zachary; (Murrieta,
CA) ; Brown; Wade H.; (Mooresville, NC) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
CENTURY-BOARD USA, LLC
Mooresville
NC
|
Family ID: |
34795183 |
Appl. No.: |
12/361488 |
Filed: |
January 28, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11417385 |
May 4, 2006 |
7491351 |
|
|
12361488 |
|
|
|
|
10764013 |
Jan 23, 2004 |
7211206 |
|
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11417385 |
|
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Current U.S.
Class: |
264/167 ;
264/175; 425/340 |
Current CPC
Class: |
B29C 43/22 20130101;
B30B 5/06 20130101 |
Class at
Publication: |
264/167 ;
425/340; 264/175 |
International
Class: |
B29C 53/68 20060101
B29C053/68; B29C 67/20 20060101 B29C067/20 |
Claims
1. A system for providing shape, surface features, or both, to a
moldable material, comprising: at least two opposed flat endless
belts spaced apart a distance, each having an inner surface and an
outer surface; a mold cavity defined at least in part by the inner
surfaces of the at least two opposed flat endless belts; and a
drive mechanism for imparting motion to the at least two opposed
flat endless belts.
2. The system of claim 1, further comprising two endless opposing
profile mold belts, each adapted to fit within the mold cavity, and
each having an inner surface adapted to shape, or mold surface
features, or both, into a moldable material, and an outer surface
in contact with the inner surface of at least one of the at least
two opposed flat endless belts.
3. The system of claim 1, wherein the outer surface of at least one
of the at least two opposed flat endless belts is supported by a
rigid supporting surface.
4. The system of claim 3, wherein the rigid supporting surface
comprises a slider bed or platen.
5. The system of claim 3, wherein the outer surface comprises a
coating of a friction reducing substance.
6. The system of claim 5, wherein the friction reducing substance
comprises a fluoropolymer or ultra-high molecular weight
polyethylene.
7. The system of claim 4, further comprising an air-film
lubrication system adapted to reduce friction between at least one
of the at least two opposed flat endless belts and the rigid
supporting surface.
8. The system of claim 7, wherein the rigid supporting surface
comprises a plurality of holes therein, in fluid communication with
a plenum chamber located near the slider bed or platen, and wherein
the holes and plenum chamber are adapted to provide pressurized air
film lubrication between the flat endless belt and the rigid
supporting surface.
9. The system of claim 1, wherein the at least two opposed flat
endless belts are adjustable such that the distance can be
varied.
10. The system of claim 2, wherein at least one of the profile mold
belts comprises an elastomeric face layer adapted to contact the
moldable material, and a reinforced backing layer adapted to
contact the inner surface of one of the opposed flat endless
belts.
11. The system of claim 2, further comprising a plurality of a
profile mold belt tensioners, adapted to maintain the profile mold
belts in tension.
12. The system of claim 11, wherein the profile mold belt tensioner
comprises one or more pulleys disposed such that the profile mold
belt encloses at least a portion of the drive mechanism.
13. The system of claim 2, wherein the opposed flat endless belts
and the profile mold belts are oriented substantially
horizontally.
14. A method of continuously forming a moldable material to have a
desired shape or surface feature or both, comprising: introducing
the moldable material into an end of a mold cavity formed at least
in part by the inner surfaces of opposed flat belts; exerting
pressure on the moldable material through the opposed flat belts;
transferring the moldable material along the mold cavity by
longitudinal movement of the opposed flat belts; removing the
molded material from the mold cavity after sufficient time has
passed for the material to cure or harden into the molded
configuration and thereby form molded material.
15. The method of claim 14, wherein the mold cavity is at least
partly defined by the inner surfaces of two opposed profiled mold
belts disposed inside the opposed flat belts, and having outer
surfaces in contact with the inner surfaces of the opposed flat
belts.
16. The method of claim 14, wherein the moldable material comprises
a filled thermoset plastic.
17. The method of claim 14, wherein the moldable material comprises
a foamed or foaming material.
18. The method of claim 15, wherein the profile mold belts form the
moldable material into a shape having a cross-section at least
approximately corresponding to that of the mold cavity.
19. The method of claim 15, wherein the profile mold belts impart a
surface pattern to the moldable material.
20. A forming apparatus for forming a moldable material, said
apparatus comprising: a first belt; a second belt opposed to said
first belt, said first and second belts spaced apart a distance,
each of said first and second belts comprising an inner surface and
an outer surface; a mold cavity defined by said inner surfaces of
said first and second belts; and a belt drive mechanism
operationally coupled to said first and second belts.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/417,385, filed May 4, 2006, currently
pending, which is a continuation of U.S. patent application Ser.
No. 10/764,013, filed Jan. 23, 2004, now U.S. Pat. No. 7,211,206,
issued May 1, 2007; the complete disclosure of all of which are
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to methods and systems for imparting
desired shape and surface characteristics to a moldable or pliable
material as the material cures or hardens. It is particularly
applicable to the shaping and embossing of thermosetting resin
systems during curing, and can be used to form these resin systems
into a variety of products, including synthetic lumber, roofing,
and siding.
[0004] 2. Description of the Related Art
[0005] Various techniques exist for continuously forming a soft or
moldable material while it hardens or cures. For example, conveyor
belts can be used to provide continuous support and movement for
materials, and in some cases the belt faces may be contoured or
profiled to mold the surfaces of the material and to impart a
shape, feature, or surface appearance to the material. Two or more
such belts may be configured to operate with the belt surfaces
opposed and the material to be molded or shaped disposed between
them. These systems can form fairly detailed three-dimensional
products.
[0006] However, when such systems are used to form a foamed
product, the structure of the overall system must be sufficiently
strong to contain the pressure of the expanding foam. The longer
the forming system and the larger the cross-section of the product
to be formed, the greater the total force due to pressure and
friction that the system must contain and overcome. As a result, in
general, belt systems have not been thought to be suitable for
formation of resin systems that involve foaming of the polymer
matrix.
[0007] Forming systems have been developed to produce large
rectangular polyurethane foam buns; these systems typically contain
the foaming material within roller-supported films or sheets. The
many rollers used in these systems contain the increase in pressure
due to foaming, and also help to minimize system friction. However,
these systems are generally not able to mold detail or texture into
the product surface.
[0008] Pullers are two-belted machines designed to grip and pull an
extruded profile. As indicated above, conventional two-belt
systems, such as pullers that utilize thick profiled belts, may be
configured to continuously mold detail and texture into a product.
However, these forming systems typically require profiled belts
with relatively thick sidewall cross sections. The thick sidewalls
minimize deflection of the unsupported sides of the mold-belt,
thereby maintaining the intended product shape, and limiting
extrusion of material through the resultant gap between belts. The
thickness of the product formed by a conventional two-belt system
is thus limited in practice by the thickness and width of the
profiled mold-belts. Thicker belts needed to form products with
deeper profiles require larger diameter end pulleys in order to
prevent excessive bending, stretching, and premature breakage of
the mold material.
[0009] In addition, most pullers are relatively short (6 feet or
less). These short forming systems tend to require slower
production speeds, allowing the product enough time in-mold to
harden sufficiently before exiting the forming unit. Longer
two-belt machines can be made, but in order to manage belt/bed
friction these longer systems typically require the use of rollers
to support the back of the profiled belts. Roller supported
mold-belts tend to allow the mold faces to separate between rollers
where the belts are unsupported, allowing material to leak between
belt faces.
[0010] To continuously mold larger foamed cross-sections and to
impart irregular shape or surface detail to the product, table-top
conveyors are frequently used. Table-top conveyors use segmented
metal mold sections attached to a metal chain-type conveyor. Two
table-top conveyors are typically arranged face-to-face when used
in this type of application, providing a rigid continuous mold.
Preventing material from migrating into the joints between adjacent
mold sections can be problematic for this type of forming system
and may required the use of plastic films disposed between the mold
and material to prevent leaks. In addition, such table-top conveyor
systems are complex and costly.
[0011] Because of the various difficulties and deficiencies
described above for existing forming systems, there remains a need
in the art for a low cost forming system that can shape a curing
polymer system, and in particular a foaming polymer system, without
leaking. There is a need for such a system that can impart surface
patterns and designs to the curing material, and that has
sufficiently low friction and thickness that it can be practically
made long enough to allow sufficient curing time in the system.
SUMMARY OF THE INVENTION
[0012] The invention disclosed in this application is a new type of
forming system utilizing up to six belts. The forming system is
uniquely suited to the continuous forming of a range of product
sizes with intricate molded-in detail. Material that may be formed
using the described system include but are not limited to:
thermoplastic and thermoset plastic compounds, highly-filled
plastic compounds, elastomers, ceramic materials, and cementitious
materials. The system is particularly suited to the forming of
foamed materials. The material to be formed may be poured, dropped,
extruded, spread, or sprayed onto or into the forming system.
[0013] In one embodiment, the invention relates to a system for
providing shape, surface features, or both, to a moldable material,
the system having:
[0014] at least two first opposed flat endless belts disposed a
first distance apart from each other, each having an inner surface
and an outer surface;
[0015] at least two second opposed flat endless belts disposed
substantially orthogonal to the first two opposed endless belts and
a second distance apart from each other, and each having an inner
surface and an outer surface;
[0016] a mold cavity defined at least in part by the inner surfaces
of at least two of the opposed flat endless belts; and
[0017] a drive mechanism for imparting motion to at least two of
the opposed flat endless belts.
[0018] In a more particular embodiment, the invention relates to a
forming system having 4 flat belted conveyors configured so as to
define and enclose the top, bottom, and sides of a 4-sided,
open-ended channel, and an additional two profiled mold-belts that
are configured to fit snugly, face-to-face within the channel
provided by the surrounding flat belts. All belts are endless and
supported by pulleys at the ends of their respective beds so as to
allow each belt to travel continuously about its fixed path.
[0019] In another embodiment, the invention relates to a method of
continuously forming a moldable material to have a desired shape or
surface feature or both, comprising:
[0020] introducing the moldable material into an end of a mold
cavity formed at least in part by the inner surfaces of two
substantially orthogonal sets of opposed flat belts;
[0021] exerting pressure on the moldable material through the
opposed flat belts;
[0022] transferring the moldable material along the mold cavity by
longitudinal movement of the belts;
[0023] after sufficient time for the material to cure or harden
into the molded configuration and thereby form molded material,
removing the molded material from the mold cavity.
[0024] The system and method are versatile, permitting the
production of a range of product sizes and profiles using the same
machine. In an exemplary embodiment, the system and method provide
for the continuous forming of synthetic lumber, roofing tiles,
molded trim profiles, siding or other building products from
heavily-filled, foamed thermoset plastic compounds and/or foamed
ceramic compounds with organic binders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1A is a top plan view, FIG. 1B is a side plan view, and
FIG. 1C is an end plan view of one embodiment of a system of the
invention.
[0026] FIG. 2 is a partially expanded isometric view of one end of
the system illustrated in FIG. 1.
[0027] FIG. 3A is an end plan view of one embodiment of the system
of the invention. FIG. 3B is an exploded sectional view of the
system of FIG. 3A.
[0028] FIG. 4 is a sectional view of a profile mold belt used in
certain embodiments of the system of the invention.
[0029] FIG. 5 is a partial sectional, partial end plan view of a
four belt configuration of the system of the invention.
[0030] FIG. 6 is a sectional view of a configuration of the system
of the invention using drive belts and supporting the sides of the
mold belts with pressurized air.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] For clarity of understanding, the invention will be
described herein with respect to a single apparatus. It should be
understood, however, that the invention is not so limited, and the
system and method of the invention may involve two or more such
systems operated in series or in parallel, and that a single system
may contain multiple sets of belts, again operated in series or in
parallel.
Flat-Belted Conveyor Channel
[0032] Each set of opposed flat belt conveyors are oriented so that
their bearing surfaces face each other. One set of opposed flat
belts can be thought of as "upper" and "lower" belts, although
these descriptors are not limiting, nor do they require that the
two opposed belts be horizontal. In practice, however, one set of
opposed belts (the upper and lower belts) will be substantially
horizontal. These belts can define the upper and lower surfaces of
a mold cavity (when the device is operated in four-belt mode), or
may provide support and drive surfaces for a set of opposed profile
mold belts (when the device is operated in six-belt mode). The
remaining set of opposed flat belts are disposed substantially
orthogonal to the first set. As used herein, the term
"substantially orthogonal" means close to perpendicular, but
allowing for some deviation from 90.degree. resulting from
adjustment of the device, variations from level in the
manufacturing floor, etc. This substantially orthogonal arrangement
is accomplished in two basic configurations.
[0033] The first exemplary configuration involves disposing the
flat bearing surfaces of the second set of belts along the sides of
the space formed by the first set of belts, thereby forming an
open-ended mold cavity that is enclosed by flat belts, and having a
length corresponding to the length of the "side" belts. This
configuration is illustrated in FIG. 5. FIG. 1A provides a top
view, FIG. 1B a side view, and FIG. 1C an end view, of a system 2
having upper flat belt 4, lower flat belt 4' upper profile mold
belt 6, lower profile mold belt 6', and side belts 8 and 8'. These
side belts extend longitudinally approximately the same distance as
the upper and lower flat belts, providing a mold cavity that is
supported from the side over virtually the entire length of the
profile mold belts. Profile mold belts 6 and 6' are maintained in
tension by tensioning rolls 10. Flat belts 4 and 4' are powered by
driven rollers 12 and 12'.
[0034] The arrangement of belts and the corresponding rollers for
this exemplary configuration can be seen in more detail in FIG. 2,
which is a partially expanded view, wherein the upper flat belt 4,
upper profile mold belt 6, and corresponding supports and rollers
10 and 12, have been lifted away from the remainder of the system
for ease of visualization. Side belts 8, 8' are supported by side
belt supports 14 and 14', and can run on side belt support rollers
16, 16'. These side belt support rollers are powered, or unpowered,
as illustrated in FIG. 2. In addition, upper and lower flat belts 4
and 4' are supported by rigid supporting surfaces, such as platens
18, 18'.
[0035] As mentioned above, each flat belt is supported by a
slider-bed or platen comprised of a rigid metal plate or other
rigid supporting surface, if the length of the belt makes such
support necessary or desirable. Generally, in order to provide
sufficient curing time for filled polyurethane foams, a support
surface is desirable but not required. The surface of the
slider-bed in one embodiment has a slippery coating or bed-plate
material attached or bonded to it (for example, ultra-high
molecular weight polyethylene, PTFE, or other fluoropolymer). Also,
the belt has a slippery backing material (for example, ultra-high
molecular weight polyethylene, PTFE or other fluoropolymer) to
reduce friction between the bed and moving belt in an exemplary
embodiment.
[0036] To further reduce friction and enhance cooling of the belts
and conveyor machinery, the slider-beds and attached slippery
surface material of a conveyor has a plurality of relatively small
holes drilled through the surface These holes are in fluid
communication with a source of compressed gas, such as air. As an
example, a plenum chamber is provided behind each slider bed, which
is then connected to a source of pressurized air. Pressurized air
fed into each plenum passes through the holes in the bed, and
provides a layer of air between the bed and the adjacent belt. This
air film provides lubrication between the bed and adjacent belt as
shown in FIG. 2., where compressed air is supplied to the plenums
through openings 20, 20'. The air fed into the plenums has a
pressure higher than the foaming pressure of the product to be
useful in reducing operating friction. In one embodiment, shop air
or high-pressure blowers are used to provide the pressurized air to
feed the plenums.
[0037] In a more particular exemplary embodiment, shown in FIG. 6,
air supply plenums are also used to provide support to the sides of
the mold belts, either directly (shown) or through side belts (not
shown). In FIG. 6, flat belts 4 and 4' are supported by upper and
lower air supply plenums 32 and 32', respectively. Areas of contact
between the belts and the plenums are prepared from or coated with
a low-friction substance, such as PTFE, or are lubricated to lower
the friction between the belts and the supporting surfaces.
Pressurized air 34 is supplied to these plenums through openings
36, 36', and exits the plenums through openings 38, 38', where it
flows under and supports flat belts 4, 4', which in turn support
the upper and lower surfaces of profile mold belts 6, 6'. In
addition, pressurized air 40 enters side plenums 42, 42' through
openings 44, 44'. The air leaves these side plenums through opening
46, 46', and flows against and supports the sides of profile mold
belts 6, 6'. This support can result either from the air flow
impinging directly on the sides of the mold belts, or from air flow
impinging on the surfaces of side belts that in turn press against
the sides of the profile mold belts. The profile mold belts, in
turn, provide support to the material being formed, 48.
[0038] The flat-belts are powered and driven at matching speeds
with respect to one another. The matched speed are achieved, in one
embodiment, by mechanical linkage between the conveyors or by
electronic gearing of the respective motors. Alternatively, an as
illustrated in FIGS. 1 and 2, only two flat belts are driven (for
example, the two opposing belts with greater contact area, which
are typically the upper and lower belts) with the remaining two
flat belts (for example, the side belts) un-driven and idling. The
flat-belts form a relatively rigid moving channel through which
contoured mold-belts and/or forming product is moved and
contained.
[0039] The driven flat-belts utilize known driven roller
technologies, including center-drive pulley mechanisms, whereby
more than 180.degree. of contact is maintained between each
conveyor's driving pulley and belt, increasing the amount of force
that may be delivered to the belt.
[0040] In another exemplary configuration, the side flat belts are
disposed substantially orthogonal relative to the upper and lower
flat belts such that their bearing surfaces face each other, and
are in a plane substantially perpendicular to the plane of the
bearing surfaces of the upper and lower belts, as illustrated in
FIG. 3. FIG. 3A is an end view with the corresponding drive and
support apparatus removed for ease of viewing. FIG. 3A shows side
flat belts 8 and 8' disposed between upper flat belt 4 and lower
flat belt 4'. An expanded sectional view of this exemplary
configuration is provided in FIG. 3B. The frames 22 and 22'
supporting the side belts are restrained in such a way as to allow
the position of the side flat belts to be adjusted laterally
providing the desired degree of pressure against the sides of
profile mold belts 6 and 6' or to accommodate mold belts of
alternate widths. This configuration provides a relatively short,
but highly contained mold cavity 24.
Mold-Belts
[0041] The contoured mold-belts are relatively thick belts with a
rubbery face material attached to a fiber-reinforced backing or
carcass as shown in FIG. 4. The profile mold belt 6' is constructed
to contain an inner surface 25, that defines part of mold cavity
24. It also has side surfaces 26, which contact side flat belts 8,
8', and outer surface 30, which contacts the inner surface of flat
belt 4'. The fiber-reinforcement 28 in the backing of the belts
will provide the strength and rigidity in the belt while the face
material has the profile, surface features, and texture that is
molded into the product. The desired mold profile, surface
features, and texture are machined, cut, bonded, and/or cast into
the surface of the mold-belts. The mold cavity created by the mold
belts has a constant, irregular, and/or segmented cross section.
Multiple cavities can be incorporated into a single set of mold
belts. Suitable mold surface materials include, but are not
restricted to Nitrile, Neoprene, polyurethane, silicone elastomers,
and combinations thereof Suitable fibers for reinforcing the
profile mold belt include cotton, aramid, polyester, nylon, and
combinations thereof.
[0042] Each profile mold-belt travels beyond the ends of the
surrounding flat-belt conveyors to a separate set of large pulleys
or rollers that maintain tension and the relative position of each
belt. In one embodiment, the mold-belts are un-powered, functioning
as idlers or slave belts to the powered flat belts behind them. In
another embodiment, the mold belts are separately powered.
[0043] The temperature of the mold belts can be adjusted during
production in the event that additional heat is needed or surplus
heat is to be removed. If the temperature of the belt surface is
adjusted, temperature controlled air is blown onto the belt
surfaces as the belts exit the flat-belted conveyor enclosure and
follow their return path to the entrance of the forming machine. In
one embodiment, infrared or other radiant heaters are used to
increase the temperature of the mold surface. In another
embodiment, temperature controlled air or other fluid is routed
through the conveyor frames to maintain predetermined process
temperatures.
Orientation
[0044] As described above, the exemplary orientation of the forming
system is for the contact surface between mold-belts to be
horizontal. The gap between the upper and lower flat-belted
conveyors (those conveyors adjacent to the backs of the
mold-belts), can be precisely maintained such that the pair of
mold-belts pass between them without being allowed to separate
(presenting a gap to the molding material) and without excessively
compressing the mold-belt shoulders or side walls. In the exemplary
embodiment, the upper conveyor is removable while not in operation
in order to permit replacement of the mold belts.
Side Conveyors
[0045] The flat-belted conveyors adjacent to the sides of the
profile mold belts provide structural support for the sides of the
mold cavity, resist any deflection of the sides due to foaming
pressure, and maintain alignment of the mold-belts. These
side-supporting conveyors permit the use of thinner mold-belt
sidewalls, which reduces the cost and mass of the mold-belts. The
use of these side-supporting conveyors also permits the molding of
deeper product cross sections without requiring excessive mold-belt
widths.
System Versatility
[0046] An exemplary configuration for the flat-belted conveyors is
for the top and bottom conveyors to be wide, with the side
conveyors sized to fit between the belts of the upper and lower
conveyors in such a way that the surface of the upper and lower
(wide) belts approach or make contact with the edges of the side
belts. The frames, pulleys, and slider-beds of the side conveyors
are slightly narrower than their respective belts to avoid contact
with the upper and lower belts. A cross section of this exemplary
configuration is shown in FIG. 3B as described above. With this
orientation, the gap between the side conveyors is adjustable in
order to accommodate wider or narrower pairs of mold-belts. This
configuration permits a range of product widths to be produced by
the same forming machine. Only the mold-belt set is replaced in
order to produce product of a different width.
[0047] To further increase the versatility of the forming machine,
the side conveyor belts, pulleys, and slider beds are replaced with
taller or shorter components and the gap between upper and lower
conveyors adjusted accordingly. This feature permits the forming
machine to accommodate mold-belts of various depths to produce
thicker or thinner cross sections.
Four-Belt Mode
[0048] The specific exemplary embodiments described above with
respect to the drawings generally relate to configuration of the
system in "six belt mode." In other words, an upper and lower flat
belt, two side flat belts, and an upper and lower profile mold
belt. The mold belts permit surface details, corner radii,
irregular thicknesses, and deeper surface texture to be molded into
the continuously formed product. However, for rectangular or square
cross-sectioned products that do not require corner radii, deep
texture, or localized features, the forming system is used without
mold-belts, and operated in "four belt mode." In this exemplary
operating configuration the four flat belts make direct contact
with the moldable product and permits the product to form within
the flat-sided cavity. When the forming system is used in this
configuration it is important that the upper and lower belts
maintain contact with the edges of the side belts to prevent
seepage of the material between adjacent belts. In order to produce
thicker or thinner products in "four belt mode" the side flat
belts, adjacent slider beds, and side belt pulleys are replaced
with components in the target thickness. The gap between side belts
is adjusted to accommodate the target width. Using this approach a
large variety of four-sided cross-sections can be produced by the
same machine without the added cost of dedicated mold-belts.
[0049] The four belt configuration is illustrated in FIG. 5. The
sectional portion of the drawing shows that the mold cavity 24 is
formed by the surfaces of upper and lower flat belts 4, 4' and the
surfaces of side belts 8, 8'.
Fabrication
[0050] The forming system structure may be fabricated using metal
materials and typical metal forming and fabricating methods such as
welding, bending, machining, and mechanical assembly.
[0051] The forming system is used to form a wide variety of
moldable materials, and has been found to be particularly suitable
for forming synthetic lumber.
[0052] Although the descriptions above describe many specific
details they should not be construed as limiting the scope of the
invention or the methods of use, but merely providing illustration
of some of the presently preferred embodiments of the
invention.
* * * * *