U.S. patent application number 10/600998 was filed with the patent office on 2004-12-16 for mold with integral screen and method for making mold and apparatus and method for using the mold.
Invention is credited to Gale, Gregory W., Haugen, Jeffrey J..
Application Number | 20040253338 10/600998 |
Document ID | / |
Family ID | 23523409 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040253338 |
Kind Code |
A1 |
Gale, Gregory W. ; et
al. |
December 16, 2004 |
Mold with integral screen and method for making mold and apparatus
and method for using the mold
Abstract
A mold with integral screen comprising a body of material having
a surface, the body has a grid-like pattern of vacuum holes
extending through the body of material and opening through said
surface and permitting a vacuum to be supplied to said surface, a
screen overlying said surface, said screen and said body being
formed of the same material as the body and being integral.
Inventors: |
Gale, Gregory W.; (Napa,
CA) ; Haugen, Jeffrey J.; (Santa Rosa, CA) |
Correspondence
Address: |
DORSEY & WHITNEY LLP
INTELLECTUAL PROPERTY DEPARTMENT
4 EMBARCADERO CENTER
SUITE 3400
SAN FRANCISCO
CA
94111
US
|
Family ID: |
23523409 |
Appl. No.: |
10/600998 |
Filed: |
June 20, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10600998 |
Jun 20, 2003 |
|
|
|
09895938 |
Jul 2, 2001 |
|
|
|
6582562 |
|
|
|
|
10600998 |
Jun 20, 2003 |
|
|
|
09385914 |
Aug 30, 1999 |
|
|
|
6287428 |
|
|
|
|
Current U.S.
Class: |
425/388 |
Current CPC
Class: |
D21J 7/00 20130101; D21J
5/00 20130101; D21J 3/00 20130101; B33Y 70/00 20141201; B33Y 80/00
20141201 |
Class at
Publication: |
425/388 |
International
Class: |
B29C 051/10 |
Claims
What is claimed:
1. A mold with integral screen comprising a body formed of a
material having a surface, said body having a grid-like pattern of
vacuum holes extending through the material and opening through
said surface and permitting a vacuum to be supplied to said surface
and a screen overlying said surface, said screen and said body
being formed of the same material as the body and being
integral.
2. A mold as in claim 1 wherein said material forming said body and
said screen is a sintered material.
3. A mold as in claim 2 wherein said grid-like pattern is formed by
a plurality of struts extending at angles with respect to each
other and providing the vacuum holes extending to the screen.
4. A mold as in claim 3 wherein the screen is formed of a plurality
of spaced-apart parallel struts extending at angles with respect to
each other and defining holes therein in communication with the
vacuum holes of the grid-like pattern of the body.
5. A mold as in claim 1 wherein said screen has a complex
surface.
6. A mold as in claim 1 wherein said screen has an exterior surface
and further including a release coating formed on the exterior
surface.
7. A mold as in claim 6 wherein said release coating is formed of
Xylan.
8. A mold as in claim 1 wherein said vacuum holes in said grid-like
pattern have substantially the same length so as to provide a
substantially uniform vacuum to the screen when a vacuum is applied
to the mold.
9. A mold as in claim 1 wherein said mold is formed of a material
which is capable of withstanding temperatures in excess of
300.degree. F.
10. A mold as in claim 7 wherein said release coating is a heat
resistant coating capable of withstanding temperatures of
430.degree. F.
11. Apparatus for producing molded pulp products by the use of
first and second mating molds being formed of a porous material and
capable of withstanding temperatures in excess of 300.degree. F., a
first manifold for carrying the first mold and means for moving the
first manifold and the first mold carried thereby into a fiber
slurry for forming the molded part of molded pulp, means for
applying a vacuum to the first manifold to cause a vacuum to be
applied to the first mold when the first mold is immersed in the
fiber slurry, a second transfer manifold mounting the second mold,
means supplying heat to the second transfer manifold and the second
mold, means for moving the second transfer manifold and the first
manifold to bring the first and second molds into engagement with
each other, means for maintaining a vacuum on the second transfer
manifold and the first manifold, means for applying heat to the
second transfer manifold to cause drying of the molded pulp carried
by the first mold to provide the molded part, means for causing
relative movement between the second transfer manifold and the
first manifold and means for at substantially the same time
supplying compressed air to the first manifold to cause the molded
part to be separated from the first mold and to move with the
second transfer mold, and means for thereafter releasing the vacuum
on the second transfer manifold to permit separation of the molded
part carried by the second transfer mold.
12. Apparatus as in claim 11 wherein said means for moving the
first manifold is capable of immersing the first mold repeatedly
into the fiber slurry until a sufficient thickness of fibers has
been formed on the first mold for the molded part.
13. A method for forming a mold with an integral screen, generating
by computer a latticework providing a mold surface having a
plurality of openings therein and grid-like support means
underlying and supporting the latticework and providing a plurality
of passages extending upwardly to and in communication with the
openings in the screen, converting the computer program into a
stereolithographic program for manufacturing the mold, latticework
and the grid-like support and means utilizing the
stereolithographic program to form the latticework and the
grid-like support means from the same material.
14. A method as in claim 13 further including the step of providing
a powder of a plastic material and sintering the powdered material
utilizing the stereolithographic program.
15. A method for producing molded parts from a fiber slurry by the
use of first and second mating porous molds, moving the first mold
into a fiber slurry and supplying a vacuum to the first mold to
cause fibers from the fiber slurry to form onto the first mold to a
desired thickness, heating the second mold, mating the first and
second molds and supplying a vacuum to the first and second molds
during mating of the first and second molds and while heating is
supplied to the second mold to cause solidification and drying of
the fibers carried by the first mold until the fibers on the first
mold are at least self-supporting to provide a molded part,
ejecting the molded part formed by the fibers so that the molded
part will travel with the second mold as the second mold is moved,
moving the second mold and releasing the vacuum on the second mold
to permit the molded part to be separated from the second mold.
16. A method as in claim 15 wherein compressed air is utilized for
ejecting the molded part from the first mold.
Description
[0001] This invention relates to a mold with integral screen and
method for making the same and particularly to a mold with integral
latticework particularly useful as a tool for making articles from
a fiber or pulp slurry to provide molded pulp parts and an
apparatus and method for using the mold to produce molded pulp
parts.
[0002] Molds have heretofore been provided for producing molded
fiber products. Typically such molds have been called wet molds
because they are dipped into a wet vat of a fiber or pulp slurry.
Such a slurry typically is made from reclaimed paper such as
newspapers, corrugated material and the like. Such molds often have
been formed of aluminum to provide the desired surface or face
through which vacuum holes extend. In such molds, the surface of
the mold is typically covered with a screen such as of stainless
steel which is sized to fit and cut and spot welded to conform
precisely to the surface of the mold to provide the mold surface.
Such screens are used to prevent the fibers from clogging the
vacuum holes. Such a screen makes it possible to disperse the
vacuum evenly over the entire surface of the mold and to prevent
the fibers from clogging the vacuum holes. Such molds typically are
quite expensive because of the time required to make the mold. In
addition with such molds, the screens can readily tear during
production requiring that the screens be repaired or replaced.
There is therefore a need for a new and improved mold or die which
overcomes the above-identified disadvantages.
[0003] In general, it is an object of the present invention to
provide a mold or die that has a body with an integral screen or
latticework and method for making the same which greatly reduces
the time and expense required for making a mold suitable for
molding products from fiber or paper pulp.
[0004] Another object of the invention is to provide a mold or die
and method of the above character in which the die can be provided
which has a body that is integral with the latticework and in which
the body and the latticework can be fabricated at the same time by
the use of the same material.
[0005] Another object of the invention is to provide a mold or die
and method of the above character which can readily accommodate
complex shapes.
[0006] Another object of the invention is to provide a mold or die
and method of the above character which provides a molded product
having unique surface texture provided by the latticework of the
mold or die.
[0007] Another object of the invention is to provide a mold or die
and method of the above character in which the architecture of the
mold incorporates a body of the material which does not adversely
affect operation of the latticework or screen.
[0008] Another object of the invention is to provide a mold or die
and method of the above character in which the mold or die can be
created with great precision.
[0009] Another object of the invention is to provide a die and
integral screen of the above character which can be produced
rapidly with great precision and at a greatly reduced cost.
[0010] Another object of the invention is to provide an apparatus
and method for using the mold or die of the above character in
which the molded pulp product can be dried by the use of heat on
the mold before the product is transferred.
[0011] Another object of the invention is to provide an apparatus
and method using the mold or die of the above character in which a
vacuum can be maintained on the molded product while heat is being
applied to the molded product.
[0012] Another object of the invention is to provide an apparatus
and method of the above character in which the mold or die when in
use will permit liquid to pass through the mold or while retaining
the fibers of the molded pulp on the surface of the mold or
die.
[0013] Another object of the invention is to provide an apparatus
and method of the above character which is used for producing a
precision molded product.
[0014] Additional objects and features of the invention will appear
from the following description in which the preferred embodiments
are set forth in detail in conjunction with the accompanying
drawings.
[0015] FIG. 1 is an isometric view of a mold or die with integral
latticework incorporating the present invention.
[0016] FIG. 2 is greatly enlarged of the view of a portion of the
latticework shown in FIG. 1 encircled by the line 2-2 of FIG.
1.
[0017] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 1.
[0018] FIG. 4 is a schematic illustration of an apparatus
incorporating the present invention utilizing the molds of the
present invention for making molded products.
[0019] FIG. 5 is an isometric top view of another embodiment of a
mold incorporating the present invention.
[0020] FIG. 6 is cross-sectional view taken along the line 6-6 of
FIG. 5.
[0021] FIG. 7 is another cross-sectional view similar to FIG. 6 but
only 0.004" in thickness.
[0022] FIG. 8 is a bottom plan view of the mold shown in FIG.
5.
[0023] In general, the die with integral latticework of the present
invention is for use as a mold in making molded pulp products from
a fiber slurry that comprises a body formed of a material. A
latticework is carried by the body to provide a mold surface for
making the molded pulp product. The latticework is provided with a
plurality of means therein spaced substantially uniformly across
the mold surface which are sized to permit a vacuum to be pulled
therethrough but to prevent fibers from the pulp from being pulled
therethrough so that the fibers from the slurry will build up on
the latticework. Means is provided by the body for supporting the
latticework on the body to provide a plurality of passages in
communication with the openings in the latticework whereby a
substantially uniformly distributed vacuum is supplied by the
latticework when a vacuum is supplied to the die. The latticework
and the means supporting the latticework are formed of the same
material.
[0024] More in particular as shown in FIGS. 1, 2 and 3 of the
drawings, the die or mold or tool 11 with integral screen or
latticework consists of a body 12 formed of a suitable material
which can be utilized in rapid prototyping and manufacturing
technology and particularly those materials suitable for use with
stereolithography. As is well known to those skilled in the art,
selective laser sintering is utilized to create solid
three-dimensional objects, layer by layer from plastic, metal or
ceramic powders that are "sintered" or fused using laser energy.
The body 12 as shown can be in the form of a parallelepiped having
spaced-apart parallel side surfaces 13 and spaced apart parallel
end surfaces 14 extending perpendicular to the side surfaces 13.
The body 12 is also provided with a bottom surface 16 (FIG. 3)
which extends at right angles to the surfaces 13 and 14 and a top
surface 17 which extends at right angles to the side and end
surfaces 13 and 14 and parallel to the bottom surface 16.
[0025] The top surface 17 of the body or block 12 has formed
therein a complex die or mold surface 21 of a desired configuration
as for example one which is recessed as shown. The mold surface 21
has complex shapes formed therein as for example curved or concave
side walls 22 adjoining convex or truncated semi-spherical surfaces
23 which adjoin spaced apart circular planar surfaces 24 that lie
in a common plane. This complex mold surface 21 has been shown in
the drawings to depict how a mold surface which has complex curves
therein can be provided in accordance with the present
invention.
[0026] A screen or latticework 31 is provided which will serve as
the mold surface 21 for making a molded pulp product as hereinafter
described. The screen or latticework 31 is provided with a
plurality of spaced-apart openings 32 which are spaced
substantially uniformly across the mold surface 21 and generally
lie in a plane having the conformation desired for the mold surface
21. The openings 32 are sized in such a manner so that the fibers
from the pulp will not be pulled through the openings 32 but will
build up to form the mold product on the screen or latticework 31
serving as the mold surface 21. The openings 32 are sized in such a
manner so that a vacuum supplied to the underside of the screen or
latticework 31 into a chamber 33 through a fitting 34 connected to
a suitable vacuum source 35 will pull the fibers from the fiber
slurry into contact with the screen or latticework 31 to form the
molded pulp product. The size of the openings can range from 0.24"
to 0.32" and can be of a desired configuration as for example
circular, square or rectangular. The preferred size has been found
to be approximately 0.24".times.0.24" when utilized in connection
with making molded products from fiber slurries made from recycled
newspapers and the like.
[0027] Means is provided as a part of the body 12 in the form of a
three-dimensional grid-like support structure 36 that provides a
plurality of passages 37 extending through the grid-like structure
and underlying the screen or latticework 31 with each of the
passages being in communication with one or more openings 32 of the
screen or latticework 31. The vacuum hereinbefore described is in
communication with the passages 37 and in conjunction with the
screen or latticework 31 supplies a vacuum which is substantially
uniformly distributed over the mold surface 21.
[0028] In connection with the present invention, it has been found
desirable to utilize the same material for forming the body 12, the
latticework 31 and the grid-like support structure 36. In
connection with the present invention it has been found to be
particularly desirable to utilize polyamides and particularly Nylon
because of its excellent heat and chemical resistance which are
desirable qualities for the dies and tools made for producing
molded pulp products of the present invention as hereinafter
described. Two materials found to be particularly suitable are
those supplied by DTM Corporation of Austin, Tex., U.S.A. and
identified as Duraform.TM. Polyamide and Duraform GF (glass-filled)
supplied by that corporation. In other applications, other
materials supplied by that corporation can be utilized such as
DuPont Somos.RTM. 201 TPE, TruForm.TM. Polymer, SandForm.TM. Zr II
and Si Foundry Sands, Copper Polyamide and RapidSteel.RTM. 2.0.
[0029] In utilizing Nylon, the Nylon powder is spread as a thin
uniform layer of a suitable thickness as for example 0.004" across
the build area by forming a powder bed with the use of a leveling
roller in a build chamber of suitable apparatus such as supplied by
DTM Corporation of Austin, Tex., and identified as the
Sinterstation.RTM. 2500.sup.plus. A cross-section of the die or
mold is selectively imaged by a computer driven program onto the
layer of powder using laser energy which heats the powder to a
temperature above its softening or melting temperature and thereby
sintering or fusing the particles into a solid mass. The laser
power is modulated so that only powder which conforms to the mold's
geometry is fused. Progressive layers of powder are thereafter
spread across the build area and rolled and imaged in the same
manner until the complete mold has been imaged and formed.
Thereafter the mold is removed from the build chamber and the loose
unfused powder is removed to provide the finished mold.
[0030] In the specific construction shown in FIGS. 1, 2 and 3, the
screen or latticework 31 is formed by the use of a plurality of
uniformly shaped articles 41 in the form of spheres having at least
four spaced-apart contact points 42 (see FIG. 2). These spheres can
be of a suitable size as for example from 0.030" to 0.090" and
preferably 0.060" to 0.070". The screen or latticework 31 formed by
the articles 41 is supported by the grid-like support structure 36
in which the passages 37 extend through the grid-like support
structure 36 which is provided with a surface 43 through which the
passages 37 extend. The articles 41 make contact with the surface
43 at points 44 to define subways 46 which extend across the
surface 43 in longitudinal and transverse directions in accordance
with the pattern formed by the articles 41 so that the openings 32
between the articles 41 are in communication with the subways 46
and the subways 46 are in communication with the passages 37 in the
grid-like support structure.
[0031] From the foregoing description it can be seen that the size
of the openings 32 and the subways 46 can be readily changed by
merely changing the size of the spherical articles 41. For the
articles 41 instead of using spheres, it should be appreciated that
other geometric shapes can be utilized as for example polyhedrons
having six or more surfaces. Thus for example a polyhedron having
eight surfaces with four planar surfaces at the top forming a
four-sided-pyramid and four surfaces at the bottom forming another
four-sided pyramid with the two pyramids being joined together to
provide an eight-sided polyhedron. Such an eight-sided polyhedron
has four corners or points which lie in a plane which can be
adjoined to corners of adjacent polyhedrons to thereby in effect
provide a latticework which has openings 32 extending therethrough
which are in communication with subways 46 that are in
communication with the passages 37 of a grid-like support
structure. Similarly, it can be seen that the articles can be
formed as truncated polyhedrons as for example a four-sided pyramid
with the bottom side of the pyramid facing upwardly to provide a
planar surface having openings 32 therebetween and having subways
46 therebelow in communication with the passages 37 of a grid-like
support structure 36. All of these various constructions can be
readily formed utilizing the technology hereinbefore described.
[0032] Molds made in accordance with the present invention have
been by way of example made of Duraform.TM. Nylon which is an
FDA-approved grade Nylon which can readily accommodate operating
temperatures of 300.degree. F. It has been found, however, that the
exterior surfaces of such molds since they are formed of Nylon
which is originally in a powder state have in minutiae a rough
surface which can inhibit the release of the that has been molded.
To enhance the release characteristics of the mold, the exterior
surface of the mold is coated with a heat-resistant material
identified as Xylan.TM. which can withstand temperatures up to
450.degree. F. Xylan is a fluorocarbon coating. This material is
sprayed on in three successive layers, each of 2-3 mil in thickness
and each layer being post-cured at 300.degree. F. for 30 minutes on
each layer. This coating 48 can be colored. Yellow has been
selected as an appropriate color because it makes the fibers
appearing on the mold to be more visible. It has been found that
this coating 48 provides a very smooth, slippery surface which
provides the mold with greatly enhanced release
characteristics.
[0033] Another mold or tool incorporating the present invention is
shown in FIGS. 5, 6 and 7. As shown therein, the mold 91 is formed
of a suitable material such as the Duraform Nylon hereinbefore
described by use of a Sinterstation as hereinbefore described. The
mold 91 is provided with a circular frame 92 which is provided with
a radially extending flange 93 having bolt holes 94 therein. The
mold 91 is in the form of a truncated cone 96 which is provided
with an inclined surface 97 and a planar circular surface 98 which
adjoins the inclined surface 97. A truncated cone-shaped recess 101
is provided within the cone 96 and has a conformation generally
corresponding to the cone 96 but of smaller dimensions so that
there remains a body 106 which is supported by the frame 92. The
body 106 includes a grid-line support structure 107 which is
overlaid by a screen or latticework 108 which forms the outer
surfaces 96 and 97 of the truncated cone 96.
[0034] The grid-like support structure 107 is a plurality of
spaced-apart parallel struts 111 extending in one direction and a
plurality of additional spaced-apart struts 112 forming the
grid-line structure 107. The struts can have a suitable thickness
as for example 0.042" with the spaced between the struts in both
directions being approximately 1/4" to provide holes 116 which are
rectangular in cross-section and have a suitable dimension as for
example 1/4" by 1/4". These holes extend from the space provided by
the cone-shaped recess 101 which is exposed to a vacuum and which
extend to the screen or latticework 108. It can be seen that by
providing the cone-shaped recess 101, the holes 116 have a length
which is substantially equal so that the length of the flow
passages for the vacuum to travel to the screen or latticework 108
is substantially the same to thereby provide a substantially
uniform vacuum over the screen or latticework 108.
[0035] The screen or latticework 108 is formed of a single layer of
material which is supported by the grid-like structure 107 which is
shown in the top circular surface 98 and which is formed by a
plurality of spaced-apart parallel struts 121 and a plurality of
additional spaced-apart parallel struts 122 extending at right
angles to the struts 121 to provide holes 123 between the same.
These struts 121 and 122 can have a suitable thickness as for
example 0.020" and having rectangular holes 123 therebetween of a
suitable size as for example 0.02" by 0.020". This same type of
hole pattern is continued down over the inclined surface 97.
Because of this inclined surface, the holes 126 therein are in the
form of inclined parallelograms and are of such a larger size as
for example 0.020" by 0.04". The struts are of a suitable thickness
as for example 0.040".
[0036] A logo or other identification 131 can be provided on the
top surface 98 which mold would be incorporated into the part made
from the mold. If desired, this logo 131 can be imperforate. The
struts 127 and 128 define the holes 126 are elliptical and form
ellipses on the inclined surface 97.
[0037] A mating mold (not shown) can be prepared in a similar
manner. The molds thus prepared can be coated with the coating of
the type hereinbefore described to enhance the release
characteristics for the mold. The mold 91 and its mating mold can
be utilized in the apparatus shown in FIG. 4 and can be utilized in
the same manner to produce molded parts therefrom. The molded parts
produced from such molds have a very pleasing appearance which
corresponds to the appearance of the exterior surface of the mold,
thus providing a molded part which is precision molded and which
also has a very pleasing, relatively smooth surface.
[0038] From the molds shown in FIGS. 6 through 8 it can be seen
that very sophisticated molds can be prepared in accordance with
the present invention within relatively short periods of time and
at relatively low cost. Thus such molds can be utilized for short
run molded products when that becomes necessary.
[0039] Molded pulp products of the desired configuration can be
made in molded pulp product producing apparatus 51 as shown in FIG.
4. In such apparatus, a tool set 52 is required formed of a female
mold or tool 53 and a mating male mold or tool 54. Such molds or
tools can be readily prepared in accordance with the present
invention. For example the desired part can be drawn utilizing a
CAD data format in a conventional computer and transferring it by
disk to an STL format to the Sinterstation.RTM. 2500.sup.plus
hereinbefore described. The surfaces to be generated for the female
and male molds are obtained by selecting the appropriate surfaces
of the part and then inputting the desired thickness for the molded
part to provide the necessary space between the female and male
molds. Both the female and male molds are then formed in the
Sinterstation.RTM. 2500.sup.plus by forming each of the molds with
the screen or latticework 31 having the openings 32 therein and
defining the surfaces of each mold.
[0040] The molds 53 and 54, after they have been prepared, are
placed in the apparatus 52 by mounting the female mold 53 on a
manifold 61 mounted on a plunger 62. The plunger 62 reciprocates
vertically to bring the manifold 61 with its female mold 53 down
into a fiber slurry 63 disposed in a holding tank 64 and out of the
slurry 63. The manifold 61 is connected by piping 66 to a vacuum
source 67. It is also connected by piping 68 to a source of
compressed air 69.
[0041] The male mold or tool 54 is mounted on a transfer manifold
71 which is carried by a plunger 72 that also reciprocates
vertically and is movable upwardly and downwardly with respect to
the manifold 61. This transfer manifold 71 is connected by piping
76 to the vacuum source 67. It is also connected by piping 77 to a
source of hot air 78.
[0042] The vacuum source 67 typically should be capable of
producing a vacuum ranging from 26-29" of Hg with a preferable
vacuum being approximately 28.5" of Hg. The hot air source 78
produces hot air under positive pressure at a temperature ranging
from 250-310.degree. F. with a preferred temperature of
approximately 290.degree. F. and a pressure ranging from 15 to 100
psi with preferably a pressure of approximately 50 psi.
[0043] The tool set 52 shown in FIG. 4 can be utilized for
producing a molded pulp product which is capable of providing
packaging for a fragile product such as champagne flutes. Such tool
by way of example can be 9" in length, 5" in width and 6" in
height.
[0044] In producing the molded pulp product, the manifold 61 is
repeatedly lowered into the slurry 66. As soon as the manifold 61
and the female tool or mold 53 are completely immersed in the fiber
slurry, a vacuum is supplied from the vacuum source 67 which vacuum
is uniformly distributed throughout the tool 53 because of the
porosity of the tool provided by the passages 32, 37 and 46
hereinbefore described. The uniformly distributed vacuum over the
tool causes fibers to be withdrawn from the fiber slurry 66 and to
be deposited substantially uniformly over the entire surface of the
tool or mold 53. A sufficient thickness of fibers is collected onto
the female mold 53 which can occur on a single immersion but if
necessary after repeated immersions, with the vacuum being applied
continuously. When the desired thickness of fibers has been
achieved, the mold 53 is raised out of the slurry 63. At the same
time, transfer manifold 71 is lowered so that male tool 54 carried
thereby mates with female tool 53 to create a seal between the two
tools while at the same time maintaining a void of the desired
small dimensions between the female and male tools 53 and 54. The
male tool 54 heated by the hot air from the hot air source 78
causes drying of the molded material carried in the female tool to
dry the same while the vacuum is still being applied for removing
the moisture which is being driven off from the molded material.
The drying temperatures utilized of 300.degree. F. can be readily
accommodated by the Nylon forming the tools 53 and 54.
[0045] After the drying operation has been completed which
typically can take place in 2 to 10 seconds and usually about 5
seconds, the vacuum from the vacuum source 67 is terminated. A
burst of compressed air is also supplied at approximately the same
time from the source 69 to the manifold to aid in lift off of the
molded part from the female tool 53. Also at the same time
separation of the molds 53 and 54 occurs typically by raising of
the transfer manifold 71. A vacuum is supplied to the transfer mold
71 to aid in separation of the molded part from the female mold 53
and lifting of the molded part by the male tool 54. This separation
of the molded part is greatly facilitated by the coating 48 applied
to the exterior surface of the molds or tools. The hot air under
pressure from the hot air source 78 is terminated immediately prior
to lift off of the molded part. The transfer manifold 71 with the
tool and the molded part carried thereby after it has been raised a
sufficient distance can be shifted to overlie a conveyor belt (not
shown) and thereafter, the vacuum can be released to permit the
dried molded part to drop off of the transfer mold.
[0046] As explained previously, if the thickness of the molded pulp
formed on the female tool 53 during the initial immersion into the
fiber slurry does not produce a molded product of sufficient
thickness, even before the drying step is undertaken, the manifold
can be again lowered into the fiber slurry 66 to cause additional
fibers to be picked up on the slurry by the use of the vacuum from
the vacuum source 67. As soon as the desired thickness of the pulp
material has been provided on the female tool 53, the drying step
hereinbefore described can be accomplished.
[0047] From the foregoing it can be seen that there has been
provided a new and improved die or mold with integral screen or
latticework and a method for making the same which greatly
facilitates the production of molds, particularly those requiring
the use of screens used for forming molded pulp articles. Such dies
can be economically and rapidly manufactured to make it possible to
rapidly and readily produce different molded products having
various conformations and shapes. The use of the spheres for
forming the latticework is very desirable because they-do not
require orientation. However, as pointed out above, other uniformly
shaped articles can be utilized to achieve similar results with the
only difference being that they must be oriented with respect to
the mold surface. Such orientation can be readily accomplished with
a CAD (computer aided design) program generating the desired
pattern. There also has been provided an apparatus and method for
using the molds to produce molded products economically.
* * * * *