Note: Descriptions are shown in the official language in which they were submitted.
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SPRING-LOADED EJECTORS FOR WOOD STRAND MOLDING
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to the revolutionary wood flake molding
technology
s invented by wood scientists at Michigan Technological University during the
latter part
of the 1970s.
B. Background of the Art
Wood flake molding, also referred to as wood strand molding, is a technique
for
molding three-dimensionally configured objects out of binder coated wood
flakes having
to an average length of about 11/ to about 6 inches, preferably about 2 to
about 3 inches;
an average thickness of about 0.005 to about 0.075 inches, preferably about
0.015 to
about 0.030 inches; and an average width of 3 inches or less, most typically
0.25 to 1.0
inches, and never greater than the average length of the flakes. These flakes
are
sometimes referred to in the art as "wood strands." This technology is not to
be
15 confused with oriented strand board technology (see e.g., U.S. Patent No.
3,164,511 to
Elmendorfj wherein binder coated flakes or strands of wood are pressed into
planar
objects. In wood flake or wood strand molding, the flakes are molded into
three-
dimensional, i, e. , non-planar, configurations.
In wood flake molding, flakes of wood having the dimensions outlined above are
2o coated with MDI or similar binder and deposited onto a metal tray having
one open side,
in a loosely felted mat, to a thickness eight or nine times the desired
thickness of the
final paxt. The loosely felted wood flake mat is then covered with another
metal tray,
and the covered metal tray is used to carry the mat to a mold. (The terms
"mold" and
"die", as well as "mold die", are sometimes used interchangeably herein,
reflecting the
25 , fact that "dies" are usually associated with stamping, and "molds" are
associated with
plastic molding, and molding of wood strands does not fit into either
category.) The top
metal tray is removed, and the bottom metal tray is then slid out from
underneath the
mat, to leave the loosely felted wood flake mat in position on the bottom half
of the
mold. The top half of the mold is then used to press the mat into the bottom
half of the
3o mold at a pressure of approximately about 600 psi, and at an elevated
temperature, to
"set" (polymerize) the MDI binder, and to compress and adhere the compressed
wood
flakes into a final three-dimensional molded part. The excess perimeter of the
loosely
felted wood flake mat, that is, the portion extending beyond the mold cavity
perimeter,
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is pinched off where the part defining the perimeter of the upper mold engages
the part
defining perimeter of the lower mold cavity. This is sometimes referred to as
the pinch
trim edge.
Patent 4,440,708 and Patent 4,469,216 disclose this technology. The drawings
in Patent 4,469,216 best illustrate the manner in which the wood flakes are
deposited to
form a loosely felted mat, though the metal trays are not shown. By loosely
felted, it is
meant that the wood flakes are simply lying one on top of the other in
overlapping and
interleaving fashion, without being bound together in any way. The binder
coating is
quite dry to the touch, such that there is no stickiness or adherence, which
hold them
1o together in the loosely felted mat. The drawings of Patent 4,440,708 best
illustrate the
manner in which a loosely felted wood flake mat is compressed by the mold
halves into
a three-dimensionally configured article (see Figs. 2-7, for example).
This is a very unusual molding process as compared to a molding process one
typically thinks of, in which some type of molten, semi-molten or other liquid
material
1s flows into and around mold parts. Wood flakes axe not molten, are not
contained in any
type of molten or liquid carrier, and do not "flow" in any ordinary sense of
the word.
Hence, those of ordinary skill in the art do not equate wood flake or wood
strand
molding with conventional molding techniques.
However, during the molding process, the molded wood part produced tends to
20 adhere to the upper or lower mold half after the part is formed and the
mold is opened.
This adherence problem decreases the number of molded wood parts that can be
produced during a production run of such parts, and increases the overall cost
and time
of production leading to production inefficiency. Conventional hydraulic
ejector pins,
like those used in plastic ejection molding, could be used in connection with
a wood
25 flake molding apparatus to eject the molded part from the upper and lower
mold halves
of the apparatus, but add significant cost to the mold. Spring-loaded ejector
pins, like
those used within stamping dies, could also be used in connection with a wood
flake
molding apparatus to eject the molded parts. However, spring-loaded ejector
pins poke
holes into the loosely-felted wood flake mat as it is compressed and cured
between
3o closing upper and lower mold halves of the molding apparatus.
SUMMARY OF THE INVENTION
In the present invention, it has been surprisingly discovered that by using
one or
more spring-loaded ejector pins having a pin head diameter of at least about
0.750 inches
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or greater and a loaded ejector pin pressure of approximately about 100 psi to
1000 psi
within a mold apparatus, one can successfully mold a loosely felted wood flake
mat into
a molded part without poking holes in the mat or part, minimize or prevent
excessive
indentation and densification within the molded part at the point of contact
with the
s ejector pin, and automatically eject the molded part from the mold as it is
opened.
These and other features, advantages and objects of the present invention will
be
further understood and appreciated by those skilled in the art by reference to
the
following specification and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
1o Fig. 1 is a vertical cross-sectional view of spaced upper and lower mold
halves
made in accordance with a preferred embodiment of the present invention, with
spring-
loaded ejectors in place in the upper and lower mold halves of the mold
apparatus, and a
loosely felted mat of wood flakes in place on the lower mold half;
Fig. 2 is a vertical cross-sectional view of the mold apparatus of the
preferred
15 embodiment of the present invention, but with the mold halves closed;
Fig. 3 is a vertical cross-sectional view of the mold apparatus of the
preferred
embodiment of the present invention, but with the mold reopened and the part
removed;
and
Fig. 4 is an enlarged cross-sectional view of a spring loaded ejector.
2o DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the preferred embodiment, at least one ejector pin assembly 10 is mounted
in
each of mold halves 21 and 22 of mold 20 (Fig. 1) such that as mold 20 is
closed,
loosely felted wood flake mat 30 is compressed and cured between upper mold
half 21
and lower mold half 22 while ejector pin 11 of ejector pin assembly 10 is
compressed
2s against spring 15 (Fig. 2). When mold 20 is then opened, spring 15 causes
ejector pins
11 to eject molded part 30' from mold 20 (Fig. 3).
Ejector pin assembly 10 comprises of ejector pin 11 which further comprises of
ejector pin head 12 terminating at shoulder 13. Shank 14 extends from head 12
into the
coil of spring 15 (Fig. 4). Pin 11 articulates inwardly against spring 15 when
mold
3o halves 21 and 22 of mold 20 are closed and compressed against mat part 30
and
articulates outwardly when the mold halves are opened. Spring 15 is housed
within
housing 16, which is seated and secured in a receiving cavity bored into mold
half 21 or
22, to a depth such that the surface of housing 16 is flush with the adjacent
interior
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surface of mold half 21 or 22. Spring 15 bears against the mold half 21 or 22
at the
bottom of the housing receiving bore, and its other end, against shoulder 13
of pin 11.
Inwardly projecting annular spring retaining lip 17, at the top of housing 16,
engages
shoulder 13 of pin 11 to prevent spring 15 from forcing pin 11 out of housing
16.
s During the molding process, as mold halves 21 and 22 are closed, ejector pin
11
is compressed inwardly against spring 15 (Fig. 2) into housing 16 until shank
14
compresses against and stops at the base of housing 16, which is seated within
mold
halves 21 and 22. The length of shank 14 of ejector pin 11 relative to spring
housing 16
is such that shank 14 will bottom out against the base of spring housing 16
when the top
of pin head 12 is flush with the top surface of mold half 21 or 22.
An ejector pin access tunnel 23 extends from the exterior of mold half 21 or
22,
to the base of the bore which receives ejector pin housing 16. It is smaller
in diameter
than the shank 14, such that spring 15 surrounds its opening into the bore,
and spring 15
cannot escape through tunnel 23. The access tunnel should be of smaller
diameter than
1s the shank so the shank bottoms out at the bottom of the housing bore, and
acts as a
"stop" to prevent excess compression of the pin. A tool can be inserted
through access
tunnel 23 to dislodge stuck ejector pins. Qil can be injected to lubricate
such pins via
ejector pin access tunnel 23.
It has been surprisingly discovered that a pin head 12 diameter of
approximately
2o about 0.750 inches or greater, under a loaded ejector pin pressure of from
approximately
about 100 psi to about 1000 psi, preferably about equal to mold pressure or
less, and
most preferably at about mold pressure, will successfully eject molded part
30' with
minimal or no indentation and densification of the molded part 30' , at the
point of
contact between loosely felted wood flake mat 30 and pin head 12. The term
"loaded
25 ejector pin pressure" means the pressure exerted at the surface of ejector
pin head 12,
via spring 15, when mold 20 is closed.
Typical maximum mold pressures in wood strand molding ranges from about 300
to 700 psi, with 600 psi being most preferred. Typically during the molding
process
then, the loosely felted wood flake mat 30 is initially pressed at a maximum
mold
3o pressure of about 600 psi for a period of time. Mold pressure is then
decreased to about
200 psi or about one-third of the initial pressure for a time, and then
pressure is
decreased to a nominal level while the part continues to cure under the heat
of mold 20,
before mold 20 is opened.
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The loaded ejector pin pressure of the preferred embodiment can be greater
than
the maximum mold pressure, but about 1000 psi maximum is preferred. The loaded
ejector pin pressure of the preferred embodiment can be less than the
preferred 100 psi,
but one does not get as much ejection force from ejector pin 11 once mold
halves 21 and
s 22 of mold 20 are opened to eject molded part 30' . By utilizing a loaded
ejector pin
pressure at about mold pressure, one achieves minimal or no indentation and
densification at the point of contact between loosely felted wood flake mat 30
and pin
head 12 during the molding process, but maximum ejection force from ejector
pin 11
once mold halves 21 and 22 of mold 20 are opened to eject molded part 30' from
the
1o mold.
For example, ejector springs rated at about 1712 pounds per inch of deflection
have about a 0.313-inch deflection or about 536 pounds of resistance when
compressed
during the molding process utilizing the preferred embodiment. The ejector
pins 11
have a pin head 12 diameter of about 0.865 inch (0.5876 square inch) to exert
a loaded
1s ejector pin pressure of about 912 psi upon loosely felted wood flake mat 30
during mold
processing, while the mold pressure is about 600 psi.
If one increases the spring rating, the pin head diameter should be increased
to
compensate for undesirable loaded ejector pin pressures which might indent or
over
densify the loosely felted wood flake mat when transformed into the mold part
beyond
2o suitable parameters. Longer stroke springs and ejectors are desirable when
die thickness
allows for a longer ejector assembly.
To produce molded wood strand products, binder coated felted wood flake mat
30 is first placed between upper mold halves 21 and 22 of mold 20, overlying
the cavity
of lower mold half 21 (Fig. 1). Before compressing and curing, ejector pin
assembly 10
2s is in its original position within mold halves 21 and 22, such that ejector
pin 11 is not
depressed against spring 15 within housing 16, pin head 12 is not flush with
the surfaces
of mold halves 21 and 22, and shank 14 is not stopped against the mold at the
base of
housing 16.
Then, both mold halves 21 and 22 of mold 20 are closed to apply heat and
3o pressure to compress and cure felted wood flake mat 30 (Fig. 2). During
this
compressing and curing step, ejector pin 11 of ejector pin assembly 10 in each
of mold
halves 21 and 22 is compressed inwardly against spring 15 within housing 16
until pin
head 12 is flush with the surface of mold halves 21 and 22 of mold 20, and
shank 14 is
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stopped against the base of housing 16 to prevent indentation and
densification of felted
wood flake mat 30 at its point of contact with pin head 12.
Following the compressing and curing step, mold halves 21 and 22 of mold 20
are opened to reveal felted wood flake mat 30 which has been transformed into
molded
part 30' (Fig. 3). Molded part 30' once formed, is ejected from the opened
mold 20 via
ejector pin 11 of ejector assembly 10 when spring 15 outwardly forces shank 14
from
housing 16 until shoulder 13 is flush and stopped against inwardly projecting
spring
retaining lip 17. In this manner, pin head 12 returns to its original position
which is not
flush with the surface of mold halves 21 and 22 to eject molded part 30' from
mold 20 to
1o complete the molding process (Fig. 3).
The wood flakes used can be prepared from various species of suitable
hardwoods and softwoods used in the manufacture of particleboard.
Representative
examples of suitable woods include aspen, maple, oak, elm, balsam fir, pine,
cedar,
spruce, locust, beech, birch and mixtures thereof. Aspen is preferred.
1s Suitable wood flakes can be prepared by various conventional techniques.
Pulpwood grade logs, or so-called round wood, are converted into flakes in one
operation with a conventional roundwood flaker. Logging residue or the total
tree is
first cut into fingerlings in the order of 2-6 inches long with a conventional
device, such
as the helical comminuting shear disclosed in iJ.S. Patent No. 4,053,004, and
the
20 'fingerlings are flaked in a conventional ring-type flaker.
Roundwood flakes generally are higher. quality and produce stronger parts
a
because the lengths and thickness can be more accurately controlled. Also,
roundwood
flakes tend to be somewhat flatter, which facilitates more efficient blending
and the logs
can be debarked prior to flaking which reduces the amount of less desirable
fines
2s produced during flaking and handling. Acceptable flakes can be prepared by
ring
flaking fingerlings and this technique is more readily adaptable to accept
wood in poorer
form, thereby permitting more complete utilization of certain types of residue
and
surplus woods.
Irrespective of the particular technique employed for preparing the flakes,
the
3o size distribution of the flakes is quite important, particularly the length
and thickness.
The wood flakes should have an average length of about 11/ inch to about 6
inches and
an average thickness of about 0.005 to about 0.075 inches. The average length
of the
wood flakes is preferably about 2 to about 3 inches. In any given batch, some
of the
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flakes can be shorter than 11/a inch, and some can be longer than 6 inches, so
long as the
overall average length is within the above range. The same is true for the
thickness.
The presence of major quantities of flakes having a length shorter than about
11/
inch tends to cause the mat to pull apart during the molding step. The
presence of some
fines in the mat produces a smoother surface and, thus, may be desirable for
some
applications so long as the majority of the wood flakes, preferably at least
75 % , is
longer than 1 1/8 inch and the overall average length is at least 11/a inch.
Substantial quantities of flakes having a thickness of less than about 0.005
inches
should be avoided, because excessive amounts of binder are required to obtain
adequate
to bonding. On the other hand, flakes having a thickness greater than about
0.075 inch are
relatively stiff and tend to overlie each other at some incline when formed
into the mat.
Consequently, excessively high mold pressures are required to compress the
flakes into
the desired intimate contact with each other. For flakes having a thickness
falling within
the above range, thinner ones produce a smoother surface while thick ones
require less
binder. These two factors are balanced against each other for selecting the
best average
thickness for any particular application. The average thickness of the flakes
preferably
is about 0.015 to about 0.25 inches, and more preferably about 0.0020 inch.
The width of the flakes is less important. The flakes should be wide enough to
ensure that they lie substantially flat when felted during mat formation. The
average
2o width generally should be about 3 inches or less and no greater than the
average length.
For best results, the majority of the flakes should have a width of about 1/16-
inch to
about 3 inches, and preferably 0.25 to 1.0 inches.
The blade setting on the flaker can primarily control the thickness of the
flakes.
The length and width of the flakes are also controlled to a large degree by
the flaking
2s operation. For example, when the flakes are being prepared by ring flaking
fingerlings,
the length of the fingerlings generally sets the maximum lengths. Other
factors, such as
the moisture content of the wood and the amount of bark on the wood affect the
amount
of fines produced during flaking. Dry wood is more brittle and tends to
produce more
fines. Bark has a tendency to more readily break down into fines during
flaking and
3o subsequent handling than wood.
While the flake size can be controlled to a large degree during the flaking
operation as described above, it usually is necessary to use some sort of
classification in
order to remove undesired particles, both undersized and oversized, and
thereby ensure
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the average length, thickness and width of the flakes are within the desired
ranges.
When roundwood flaking is used, both screen and air classification usually are
required
to adequately remove both the undersize and oversize particles, whereas
fingerling flakes
usually can be properly sized with only screen classification.
Flakes from some green wood can contain up to 90 % moisture. The moisture
content of the mat must be substantially less for molding as discussed below.
Also, wet
flakes tend to stick together and complicate classification and handling prior
to blending.
Accordingly, the flakes are preferably dried prior to classification in a
conventional type
drier, such as a tunnel drier, to the moisture content desired for the
blending step. The
to moisture content to which the flakes are dried usually is in the order of
about 6-weight
or less, preferably about 2 to about 5-weight % , based on the dry weight of
the
flakes. If desired, the flakes can be dried to a moisture content in the order
of 10 to 25
weight % prior to classification and then dried to the desired moisture
content for
blending after classification. This two-step drying may reduce the overall
energy
15 requirements for drying flakes prepared from green woods in a manner
producing
substantial quantities of particles which must be removed during
classification and, thus,
need not be as thoroughly dried.
To coat the wood flakes prior to being placed as a loosely felted wood flake
mat
30 within the cavity of lower mold half 22 within mold 20 of the preferred
embodiment,
2o a known amount of the dried, classified flakes is introduced into a
conventional blender,
such as a paddle-type batch blender, wherein predetermined amounts of a
resinous
particle binder, and optionally a wax and other additives, is applied to the
flakes as they
are tumbled or agitated in the blender. Suitable binders include those used in
the
manufacture of particleboard and similar pressed fibrous products and, thus,
are badly
2s referred to herein as "resinous particle board binders." Representative
examples of
suitable binders include thermosetting resins such as phenolformaldehyde,
resorcinol-
formaldehyde, melamine-formaldehyde, urea-formaldehyde, urea-furfuryl and
condensed
furfuryl alcohol resins, and organic polyisocyantes, either alone or combined
with urea-
or melamine-formaldehyde resins.
3o Particularly suitable polyisocyanates are those containing at least two
active
isocyanate groups per molecule, including diphenylmethane diisocyanates, m-
and p-
phenylene diisocyanates, chlorophenylene diisocyanates, toluene di- and
triisocyanates,
triphenylinethene triisocyanates, diphenylether-2,4,4'-triisoccyanate and
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polyphenylpolyisocyanates, particularly diphenylmethane-4,4'-diisocyanate. So-
called
MDI is particularly preferred.
The amount of binder added to the flakes during the blending step depends
primarily upon the specific binder used, size, moisture content and type of
the flakes,
s and the desired characteristics of the part being formed. Generally, the
amount of
binder added to the flakes is about 2 to about 15-weight % , preferably about
4 to about
10-weight % , as solids based on the dry weight of the flakes. When a
polyisocyanate is
used alone or in combination with a urea-formaldehyde resin, the amounts can
be more
toward the lower ends of these ranges.
1 o The binder can be admixed with the flakes in either dry or liquid form. To
maximize coverage of the flakes, the binder preferably is applied by spraying
droplets of
the binder in liquid form onto the flakes as they are being tumbled or
agitated in the
blender. When polyisocyantes are used, a conventional mold release agent
preferably is
applied to the die or to the surface of the felted mat prior to pressing. To
improve water
15 resistance of the part, a conventional liquid wax emulsion preferably is
also sprayed on
the flakes during the blinding step. The amount of wax added generally is
about 0.5 to
about 2 weight % , as solids based on the dry weight of the flakes. Other
additives, such
as at least one of the following: a coloring agent, fire retardant,
insecticide, fungicide,
mixtures thereof and the like may also be added to the flakes during the
blending step.
2o The binder, wax and other additives, can be added separately in any
sequence or in
combined form.
The mixture of binder, wax and flakes or "furnish" from the blending step is
formed into a loosely felted, layered wood flake mat 30, which is placed
within the
cavity of lower mold half 22 prior to the molding and curing of the mat into a
molded
25 wood particle product. The moisture content of the flakes should be
controlled within
certain limits so as to obtain adequate coating by the binder during the
blending step and
to enhance binder curing and deformation of the flakes during molding.
The presence of moisture in the flakes facilitates their bending to make
intimate
contact with each other and enhances uniform heat transfer throughout the mat
30 during
3o the molding step, thereby ensuring uniform curing. However, excessive
amounts of
water tend to degrade some binders, particularly urea-formaldehyde resins, and
generate
steam which can cause blisters. On the other hand, if the flakes are too dry,
they tend to
absorb excessive amounts of the binder, leaving an insufficient amount on the
surface to
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obtain good bonding and the surfaces tend to cause hardening which inhibits
the desired
chemical reaction between the binder and cellulose in the wood. This latter
condition is
particularly true for polyisocyanate binders.
Generally, the moisture content of the furnish after completion of blending,
s including the original moisture content of the flakes and the moisture added
during
blending with the binder, wax and other additives, should be about 5 to about
25 weight
%, preferably about 5 to about 7 weight % . Generally, higher moisture
contents within
these ranges can be used for polyisocyanate binders because they do not
produce
condensation products upon reacting with cellulose in the wood.
to The furnish is formed into a generally flat, loosely felted, mat,
preferably as
multiple layers. A conventional dispensing system, similar to those disclosed
in U.S.
Pat. Nos. 3,391,223 and 3,824,058, and 4,469,216 can be used to form the mat.
Generally, such a dispensing system includes trays, each having one open side,
carried
on an endless belt or conveyor and one or more (e.g., 3) hoppers spaced above
and
15 along the belt in the direction of travel for receiving the furnish.
When a mufti-layered mat is formed in accordance with a preferred embodiment,
a plurality of hoppers usually are used with each having a dispensing or
forming head
extending across the width of the forming belt for successively depositing a
separate
layer of the furnish as the tray is moved beneath the forming heads. Following
this, the
2o tray is taken to mold 20 to place the loosely felted mat 30 within the
cavity of lower
mold half 22, by sliding the tray out from under mat 30.
In order to produce molded wood strand products having the desired edge
density
characteristics without excessive blistering and springback, the loosely
felted mat 30
should preferably have a substantially uniform thickness and the flakes should
lie
25 substantially flat in a horizontal plane parallel to the surface of the
forming belt and be
randomly oriented relative to each other in that plane. The uniformity of the
mat
thickness can be controlled by depositing two or more layers of the furnish on
the
forming belt and metering the flow of furnish from the forming heads.
Spacing the forming heads above the forming belt so the flakes must drop about
1
3o to about 3 feet from the heads en route to the carriage can enhance the
desired random
orientation of the flakes. As the flat flakes fall from that height, they tend
to spiral
downwardly and land generally flat in a random pattern. Wider flakes within
the range
discussed above enhance this action. A scalper or similar device spaced above
the
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forming belt can be used to ensure uniform thickness or depth of the mat,
however, such
means usually tend to align the top layer of flakes, i.e., eliminate the
desired random
orientation. Accordingly, the thickness of the mat preferably is controlled by
closely
metering the flow of furnish from the forming heads.
The mat thickness used will vary depending upon such factors as the size and
shape of the wood flakes, the particular technique used for forming the mat,
the desired
thickness and density of the mold wood product produced, the configuration of
the
molded wood product, and the molding pressure to be used. In addition, after
the
molded wood strand part is produced by the method of the present invention,
any
to flashing and any plugs are removed by conventional means, and the
peripheral edges of
the molded part can be trimmed to the desired final dimensions. The preferred
embodiment of the present invention can include means, which provide built-in
trimming
and removal of plugs and flashing during processing as well.
Molding temperatures, pressures and times vary widely depending upon the
15 thickness and desired density of the molded wood strand part 30' , size and
type of wood
flakes, moisture content of the flakes, and the type of binder used. The
molding
temperature used is sufficient to at least partially cure the binder and expel
water from
the loosely felted wood flake mat 30 within a reasonable time period and
without
charring the wood. Generally, a molding temperature ranging from ambient up to
about
20 450° F. can be used. Temperatures above about 450° F. can
cause charring of the
wood. When a binder system including, a urea-formaldehyde resin and a
polyisocyanate
is used, a molding temperature of about 250° to about 375° F. is
preferred, while a
molding temperature of about 300° to about 425° F. is preferred
for phenol-
formaldehyde resin binders.
25 The molding pressure used should be sufficient to press the wood flakes
into
intimate contact with each other without crushing them to the point where
lignin starts to
exude, causing a breakdown in the fibers with a resultant degradation in
structural
integrity. The maximum molding pressure on the net die/mold area typically is
about
300 to 700 psi.
3o The time of the molding or press cycle is sufficient to at least partially
cure the
binder to a point where the molded wood part has adequate structural integrity
for
handling. The press cycle typically is about 2 to about 10 minutes; however,
shorter or
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longer times can be used when pressure-curing binders are employed when more
complete curing of certain thermosetting binders is desired.
The mold apparatus having spring-loaded ejector assemblies of the preferred
embodiment and method of ejecting molded wood parts produced using such an
embodiment solve problems of producing such parts, which were not solved by
the prior
art. The preferred embodiment and method of production using the preferred
embodiment solve the problem of molded wood parts sticking to the mold
apparatus,
increase efficiency of molded wood part production, and allow for production
of molded
wood parts in an assembly-line like fashion without having to remove each
molded part
1o by hand or other non-automated means when produced.
In addition, the preferred embodiment and method of production utilizing the
preferred embodiment allow for the surprising discovery that molded wood parts
can be
ejected from mold apparatuses without poking holes in the loosely felted wood
flake
mat, without causing excessive indentation and densification of the mat at the
point of
~s contact with the pin head, and at a low cost, by using spring-loaded
ejector assemblies
having a pin head diameter of at least about 0.750 inches or greater.
Without further elaboration, it is believed that one skilled in the art can,
using the
preceding description, utilize the present invention to its fullest extent.
The above
description, however, is that of the preferred embodiments only. Modifications
of the
2o invention will occur to those skilled in the art and to those who make or
use the
invention. Therefore, it is understood that the embodiment described above is
merely
for illustrative purposes and not intended to limit the scope of the
invention, which is
defined by the following claims as interpreted according to the principles of
patent law,
including the Doctrine of Equivalents.
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