U.S. patent application number 13/218893 was filed with the patent office on 2011-12-22 for footwear mold heating system and method.
This patent application is currently assigned to NIKE, INC.. Invention is credited to Todd A. Waatti.
Application Number | 20110309551 13/218893 |
Document ID | / |
Family ID | 38002933 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110309551 |
Kind Code |
A1 |
Waatti; Todd A. |
December 22, 2011 |
Footwear Mold Heating System and Method
Abstract
Mold assemblies for compression molding of footwear components
include molds, heating elements, conductor plates, insulating
layers and carrier trays. An upper mold assembly is placed into a
fixture attached to an upper press platen. A lower mold assembly
slides into and out of a fixture attached to a lower press platen.
Heating elements within the mold assemblies connect to electrical
contacts in the fixtures when the mold assemblies are installed in
the fixtures, thereby providing electrical power to the heating
elements and heating the molds. A conveyor is positioned to receive
a mold assembly from (or transfer a mold assembly to) the lower
press platen fixture when the lower platen is in a lowered
position.
Inventors: |
Waatti; Todd A.;
(Battleground, WA) |
Assignee: |
NIKE, INC.
Beaverton
OR
|
Family ID: |
38002933 |
Appl. No.: |
13/218893 |
Filed: |
August 26, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12474718 |
May 29, 2009 |
8029721 |
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13218893 |
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11269848 |
Nov 9, 2005 |
7556492 |
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12474718 |
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Current U.S.
Class: |
264/325 |
Current CPC
Class: |
B29L 2031/504 20130101;
B29C 43/52 20130101; B29D 35/122 20130101; B29C 33/306 20130101;
B29C 33/08 20130101; B29C 35/02 20130101; B29C 33/02 20130101; B29D
35/128 20130101 |
Class at
Publication: |
264/325 |
International
Class: |
B29C 43/14 20060101
B29C043/14 |
Claims
1. A method for molding articles, the method comprising the steps
of: positioning a first mold and a second mold between first and
second platens, wherein the positioning includes coupling a first
mold assembly to the first platen, the first mold assembly
including the first mold and a first heating element; heating the
first and second molds from one or more heat sources located
between the first and second platens, the one or more heat sources
comprising the first heating element; pressing the first and second
platens together so as to place the first and second molds into a
cooperating position whereby the first and second molds at least
partially define a mold volume; moving the first and second platens
away from one another so as to move the first and second molds out
of the cooperating position; removing the first mold assembly from
the first platen after the pressing and the moving steps; coupling
a third mold assembly to the first platen, the third mold assembly
including a third mold and a third heating element; and repressing
the first and second platens together, while heating the third mold
with the third heating element, so as to place the third and second
molds into a cooperating position whereby the third and second
molds at least partially define a mold volume.
2. The method of claim 1, further comprising: placing the first
mold and the first heating element into a first carrier to form the
first mold assembly.
3. The method of claim 2, wherein the placing step includes placing
a first conductor element into the first carrier as part of the
first mold assembly and in contact with the first heating element,
the first conductor element being formed from a material having a
thermal conductivity value higher than a thermal conductivity value
of a material from which the first mold is formed.
4. The method of claim 3, wherein the placing step includes placing
a first insulating element into the first carrier as part of the
first mold assembly and between the first conductor element and the
first carrier, the first insulating element being formed from a
material having a thermal conductivity value lower than a thermal
conductivity value of a material from which the first carrier is
formed.
5. The method of claim 1, wherein coupling the first mold assembly
to the first platen comprises sliding the first mold assembly into
a fixture attached to the first platen, removing the first mold
assembly from the first platen comprises sliding the first mold
assembly out of the fixture, and coupling the third mold assembly
to the first platen comprises sliding the third mold assembly into
the fixture.
6. The method of claim 5, wherein the pressing step further
comprises pressing the first and second platens so as to place the
first and second molds into a cooperating position whereby the
first and second molds at least partially define a mold volume that
corresponds to a footwear component.
7. The method of claim 5, wherein the mold volume at least
partially defined by the first and second molds corresponds to a
footwear component, and wherein the mold volume at least partially
defined by the second and third molds corresponds to a footwear
component.
8. The method of claim 5, wherein the first mold assembly comprises
a first conductor element, the first conductor element is formed
from a material having a thermal conductivity value higher than a
thermal conductivity value of a material from which the first mold
is formed, and the first conductor element is in contact with the
first heating element and the first mold.
9. The method of claim 8, wherein the first conductor element has a
contacting face that is adjacent to the first mold, the first mold
has a contacting face that is adjacent to the first conductor
element, and each of the contacting faces has at least one recess
formed therein and receiving at least a portion of the first
heating element.
10. The method of claim 8, wherein the first conductor element
includes upper and lower layers, the upper layer has a contacting
face that is adjacent to the lower layer, the lower layer has a
contacting face that is adjacent to the upper layer, and each of
the contacting faces has at least one recess formed therein and
receiving at least a portion of the first heating element.
11. The method of claim 8, wherein a first insulating element is
formed from a material having a thermal conductivity value lower
than a thermal conductivity value of a material from which a first
carrier is formed, the first insulating element and the first
carrier are part of the first mold assembly, and the first
insulating element is between the first conductor element and the
first carrier.
12. The method of claim 5, wherein the first mold assembly
comprises a first conductor element, the second mold is part of a
second mold assembly, the second mold assembly comprising a second
conductor element, the first and second conductor elements are
respectively formed from materials having thermal conductivity
values higher than thermal conductivity values of materials from
which the first and second molds are formed, the first conductor
element is in contact with the first heating element and the first
mold, and the second conductor element is in contact with the
second heating element and the second mold.
13. The method of claim 5, wherein the method is performed using a
system that comprises a press and at least one conveyor, the first
and second platens are part of the press, the first platen having a
pressing position in which the first and second platens are moved
together to press the second mold with one of the first or third
molds and a withdrawn position in which the first platen is moved
away from the second platen, and the conveyor is positioned to
receive one of the first and third mold assemblies from, and to
transfer one of the first and third mold assemblies to, the first
platen when the first platen is in the withdrawn position.
14. The method of claim 13, wherein the fixture includes at least
one electrical contact, the at least one electrical contact is
positioned to form an electrical connection with the first heating
element when the first mold assembly is slidingly engaged in the
fixture, and the at least one electrical contact is positioned to
form an electrical connection with the third heating element when
the third mold assembly is slidingly engaged in the fixture.
15. The method of claim 5, wherein the first heating element is
positioned in the first mold assembly such that a portion of the
first heating element is engageable with an electrical power
connection when the first mold assembly is engaged with the fixture
on the first platen, and wherein the third heating element is
positioned in the third mold assembly such that a portion of the
third heating element is engageable with the electrical power
connection when the third mold assembly is engaged with the fixture
on the first platen.
16. The method of claim 5, wherein the first heating element, the
first mold and a first carrier are separate components assembled to
form the first mold assembly and are configured for non-destructive
disassembly.
17. The method of claim 8, wherein the first heating element, the
first mold, a first carrier and the first conductor element are
separate components assembled to form the first mold assembly and
are configured for non-destructive disassembly.
18. The method of claim 10, wherein the first heating element, the
first mold, a first carrier, the first conductor element upper
layer and the first conductor element lower layer are separate
components assembled to form the first mold assembly and are
configured for non-destructive disassembly.
19. The method of claim 11, wherein the first heating element, the
first mold, the first carrier, the first conductor element and the
first insulating element are separate components assembled to form
the first mold assembly and are configured for non-destructive
disassembly.
20. The method of claim 15, wherein the first heating element, the
first mold and a first carrier are separate components assembled to
form the first mold assembly and are configured for non-destructive
disassembly.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Non-Provisional
application Ser. No. 12/474,718, filed May 29, 2009, and titled
"Footwear Mold Heating System and Method," which application is a
continuation of U.S. Non-Provisional application Ser. No.
11/269,848, filed Nov. 9, 2005, and titled "Footwear Mold Heating
System and Method," now U.S. Pat. No. 7,556,492. The contents of
both applications are incorporated by reference herein.
TECHNICAL FIELD
[0002] At least some embodiments of the invention relate to
equipment for compression molding footwear components and/or other
articles. Embodiments of the invention also relate to methods for
compression molding articles using such equipment.
BACKGROUND
[0003] Compression molding is a manufacturing process used to
fabricate a large variety of articles. In compression molding, raw
material is typically placed into an open cavity in a first portion
of a mold. The raw material, which may be rubber or some other type
of thermosetting material, is typically in solid form. The raw
material may be a single piece, may be in multiple pieces, or may
even be a powder. A second portion of the mold is then attached to
(or otherwise placed into contact with) the first portion. As heat
and pressure are applied, the raw material in the mold cavity is
formed into the desired shape.
[0004] Compression molding is often used when manufacturing
footwear. In particular, midsoles, outsoles, and various other
footwear components are frequently formed from rubber, plastic
and/or other materials which are heated and pressed into desired
shapes. FIGS. 1A-1C are partially schematic drawings of a typical
procedure for compression molding footwear components according to
the prior art. FIG. 1A shows a first mold 2 and a second mold 3 for
a pair of shoe outsoles. Cavities 4 and 5 are formed in first mold
2. The bottom of cavity 4 corresponds to a bottom surface of a left
shoe outsole, and the bottom of cavity 5 corresponds to a bottom of
a right shoe outsole. Second mold 3 includes a pair of protrusions
6 and 7 which respectively correspond to the top surfaces of the
left and right shoe outsoles.
[0005] One or more pieces of the raw material(s) for the outsoles
are placed into each of cavities 4 and 5. As shown in FIG. 1B,
second mold 3 is then placed on first mold 2 so that protrusions 6
and 7 extend into cavities 4 and 5, with spaces between the
protrusions and the cavity walls forming mold volumes corresponding
to the outsoles being produced. As seen in FIG. 1C, the joined
molds are then placed between two platens 8 and 9 of a press.
Platens 8 and 9 are then heated by source(s) internal to the
platens. Heat from platens 8 and 9 is transferred to molds 2 and 3
as platens 8 and 9 are pressed together. The pressure and heat is
maintained for a time sufficient for the raw material to fill the
mold volumes and to set. Depending upon the material(s) being used,
this may be several minutes or more.
[0006] Conventional compression molding equipment and methods (such
as those described above) can present challenges. So as to
withstand the pressing forces, platens are often substantial
structures which contain large masses of metal. In order to
transfer sufficient heat to the molds, a significant amount of heat
must be applied to the platens. The platens may also be wider
and/or longer than the molds (as seen in FIG. 1C). In such a case,
the platens may be heated in areas which are not in contact with
(and thus do not transfer significant heat to) the molds. These
configurations can thus be thermally inefficient. Moreover, a
relatively long amount of time may be needed to transfer sufficient
heat from the platens to the molds. In addition to being
inconvenient, extended heating times can slow production.
[0007] Conventional arrangements may also limit the precision with
which mold heating can be controlled. Different types of materials
must be heated to different temperatures. Because the heat source
is relatively far from the molds in the arrangement of FIG. 1C,
heating the molds within a specific temperature range may be
difficult. Moreover, different molds may have different internal
geometries. For example, some molds may be thicker in certain
regions, and therefore require more heat in those regions to reach
a desired temperature. Heating sources within the platens are
usually in a fixed (and sometimes unknown) configuration. It may
therefore be impractical to rearrange those heating sources based
on the geometry of a particular mold.
[0008] Conventional platen-mold systems can also require excessive
time to cool. Some materials (e.g., Phylon) require that the mold
cool before the platens are released from the mold. Excessive
cooling times can thus slow production when using such
materials.
[0009] Yet another challenge presented by conventional compression
molding techniques relates to handling of a mold before (and/or
after) the mold is pressed. For many types of footwear, significant
time is needed to prepare a mold for production. For example,
certain shoe outsoles are formed from multiple types of material.
This may be for aesthetic reasons (e.g., color "pops" for forming
multicolored outsoles), for structural reasons (e.g., to place a
harder or softer material in certain outsole regions), or for other
reasons. When preparing to mold such an outsole, separate pieces of
different raw materials must be carefully placed at the proper
locations in the mold. Trimming of raw materials may also be
needed. Arrangements which enhance an operator's ability to prepare
one mold while another is being heated and pressed can increase
productivity.
SUMMARY
[0010] This summary introduces, in a simplified form, concepts that
are further described below in the detailed description. This
summary is not intended to identify key or essential features of
the claimed subject matter, and is not intended to be used as an
aid in determining the scope of the claims.
[0011] In at least some embodiments, heating elements are located
near a mold and between platens used to press a mold and a mating
mold together. Multiple molds and heating elements may be placed in
a carrier tray to form a mold assembly. In some embodiments, mold
assemblies may include a conductor plate which contacts the heating
elements and the mold. The conductor plate, which may have a higher
thermal conductivity value than the mold, spreads the heat from the
heating elements. A layer of insulating material may also be placed
between the conductor plate and the carrier tray.
[0012] In certain embodiments, a mold assembly is received within a
fixture attached to a press platen. Heating elements within the
mold assembly connect to electrical contacts in the fixture when
the mold assembly is installed in the fixture, thereby powering the
heating elements and heating the mold. In certain embodiments,
separate mold assemblies are formed for upper and lower portions of
mating molds. One of those mold assemblies is retained within a
first fixture attached to a first press platen. Another of those
mold assemblies slides into and out of a second fixture attached to
a second press platen. A conveyor is positioned to carry the mold
assemblies which slide into and out of the second platen.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing summary, as well as the following detailed
description of the preferred embodiments, is better understood when
read in conjunction with the accompanying drawings, which are
included by way of example, and not by way of limitation with
regard to the claimed invention.
[0014] FIGS. 1A-1C are partially schematic drawings showing
compression molding of footwear components according to a prior art
arrangement.
[0015] FIG. 2 shows a system for molding footwear components
according to at least some embodiments.
[0016] FIG. 3 is an enlarged front perspective view of various
elements from the system of FIG. 2.
[0017] FIG. 4 shows a lower mold assembly partially withdrawn from
a lower positioning fixture.
[0018] FIG. 5 shows a lower mold assembly fully engaged in a lower
positioning fixture.
[0019] FIG. 6 is a side perspective view of a lower mold assembly
fully engaged in a lower positioning fixture.
[0020] FIG. 7 is a lower front perspective view of an upper mold
assembly secured in an upper positioning fixture.
[0021] FIG. 8 is a lower front perspective view of an upper
positioning fixture.
[0022] FIG. 9 is a front perspective view of a lower mold assembly
with one mold removed.
[0023] FIGS. 10A-10C show alternate configurations for positioning
heating elements.
[0024] FIG. 11A is a cross-sectional view of a lower mold
assembly.
[0025] FIG. 11B is a cross-sectional view of a lower mold assembly
according to another embodiment.
[0026] FIG. 12 is a partially schematic top view of an alternate
arrangement of heating elements.
[0027] FIGS. 13A-13E illustrate a sequence of operations using mold
assemblies such as those described in connection with previous
drawing figures.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] So as to provide a convenient example, embodiments of the
invention are described by reference to a system configured to mold
footwear outsoles. However, the invention is not limited to systems
or methods for molding outsoles. In other embodiments, the
invention includes systems and methods for molding midsoles,
insoles, combined outsoles/midsoles, and other footwear components.
Indeed, the invention is not limited to footwear, and includes
embodiments in which other types of components can be molded.
[0029] FIG. 2 shows a system for molding footwear components
according to at least some embodiments of the invention. Included
in the system of FIG. 2 is a press 21. Press 21 includes an upper
clamp plate 22 and a lower clamp plate 23. Clamp plates 22 and 23
move relative to one another so as to compress mating molds placed
between clamp plates 22 and 23. In the depicted arrangement, upper
plate 22 is stationary and lower plate 23 is moved toward upper
plate 22 (along rails 24) by one or more hydraulic rams (not
shown). The force of lower plate 23 in the direction of upper plate
22 is thereby transferred to compress mating molds placed between
the upper and lower clamp plates. Instrumentation, power and
control equipment for press 21 is contained inside a cabinet 25. It
is to be noted that presses per se are well known and are
commercially available from a variety of sources. Press 21 is
intended to generically represent any of a variety of different
types of equipment which can be employed to apply force between two
surfaces. The invention is not dependent on the particular type of
press which is utilized. Instead, embodiments of the invention can
be implemented using any of a variety of different press types.
[0030] Although partially obscured in the view of FIG. 2, an upper
positioning fixture 26 is attached to the underside of upper clamp
plate 22. Similarly, a lower positioning fixture 27 is attached to
lower plate 23. Fixture 26 and fixture 27 each receives and
positions a mold assembly. The mold assemblies, which are described
in more detail below, contain mold elements that are compressed
together to produce one or more articles. In the present example,
the mold assemblies are used to manufacture a pair of outsoles. In
particular, upper fixture 26 positions an upper mold assembly 30.
Upper mold assembly 30 includes upper molds 32 and 33. Lower
fixture 27 positions a lower mold assembly 31, which includes lower
molds 34 and 35. Lower molds 34 and 35 have mold cavities 80 and 81
(see, e.g., FIG. 3). Surfaces of cavities 80 and 81 respectively
correspond to lower surfaces of left and right outsoles being
produced. Upper molds 32 and 33 have protrusions 94 and 95 (see,
e.g., FIG. 7), which respectively fit within cavities 80 and 81,
and which respectively correspond to upper surfaces of left and
right outsoles being produced. During a molding operation, movement
of lower clamp plate 23 toward upper clamp plate 22 causes lower
molds 34 and 35 to be moved into positions whereby protrusions 94
and 95 are respectively forced into cavities 80 and 81. Raw
material in the mold volumes (i.e., the spaces between the
protrusions and the cavity walls) is thereby subjected to pressure.
The molds are simultaneously heated (as described below), and the
raw material is formed into left and right outsoles.
[0031] As also seen in FIG. 2, the system can be used with a single
upper mold assembly and multiple lower mold assemblies.
Specifically, fixture 26 retains upper mold assembly 30 during
multiple molding cycles. Conversely, lower fixture 27 may
alternately receive a different one of several lower mold
assemblies 31 during separate molding cycles. Lower mold assemblies
31 slide into and out of lower fixture 27 along conveyors 40 and
41. As described in more detail below, this permits an operator to
prepare one lower mold assembly 31 while another lower mold
assembly 31 is being pressed with upper mold assembly 30.
[0032] FIG. 3 is an enlarged front perspective view of upper and
lower fixtures 26 and 27, upper and lower mold assemblies 30 and
31, and conveyors 40 and 41. For simplicity, clamp plates 22 and 23
and other aspects of the system are not shown. Upper fixture 26
includes multiple guide pins 42. Guide pins 42 are received in
guide holes 43 of lower fixture 27 during a molding operation, and
align upper fixture 26 with lower fixture 27. Conveyors 40 and 41
are positioned at a height corresponding to the position of a lower
mold assembly 31 within lower fixture 27 when lower clamp plate 23
is in the down position (as shown in FIG. 2). In this manner, a
lower mold assembly 31 can be readily removed from (or inserted
into) lower fixture 27 by sliding lower assembly 31 over rollers 44
of conveyors 40 and 41. A handle 45 attached to a front edge of a
carrier tray 55 of lower mold assembly 31 allows the lower mold
assembly to be easily removed from lower fixture 27.
[0033] FIG. 3 also shows how at least some embodiments differ from
conventional arrangements for compression molding of footwear
components. Unlike previous arrangements which would have applied
heat to molds 34 and 35 by heating press platens (such as upper and
lower clamp plates 22 and 23), the heat source for heating molds 34
and 35 includes heating elements 50a-50d within lower mold assembly
31. Similarly, the heat source for molds 32 and 33 includes heating
elements 51a-51d within upper mold assembly 30. Because the heat
sources are between the clamp plates and closer to the molds, less
metal must be heated. Accordingly, less time is required for
heating the molds. Because a smaller amount of metal is heated, the
molds can also cool more rapidly. Moreover, location of the
multiple heat sources closer to the inner mold volume allows more
precise control of molding temperatures.
[0034] FIG. 4 shows lower fixture 27 with lower mold assembly 31
partially withdrawn. Other portions of the system are not shown.
Lower carrier tray 55 of lower mold assembly 31 has an outer shape
that fits within, and generally corresponds to, surfaces 56a (the
inside surface of the left side wall of lower fixture 27), 56b (the
inside bottom surface of fixture 27) and 56c (the inside surface of
the right side wall of lower fixture 27). Bracket 57 is positioned
at the rear of lower fixture 27, and includes a flange 58 having a
front edge 59. When lower mold assembly 31 is slid into place
within lower fixture 27, front edge 59 abuts the rear side of
carrier tray 55 and prevents lower mold assembly 31 from sliding
any further to the rear. In this manner, front edge 59 and surfaces
56a and 56c laterally position lower mold assembly 31 for a molding
operation. Electrical connectors 60a-60d are also mounted on
bracket 57. When lower mold assembly 31 is pushed into and is fully
engaged within lower fixture 27, electrical connectors 60a-60d are
respectively attached to mating connectors on the rear ends 61a-61d
of heating elements 50a-50d (rear end 61a of heating element 50a is
obscured in FIG. 3). Electrical power is then supplied to heating
elements 50a-50d through connectors 60a-60d. For simplicity,
electrical connectors 60a-60d are shown generically in the
drawings, and mating connectors on rear ends 61a-61d are omitted.
Various types of commercially available electrical connectors can
be used for electrical connectors 60a-60d and for mating connectors
on rear ends 61a-61d. Additional details of heating elements
50a-50d, of electrical connections to those heating elements, and
of heating element operation are provided below in conjunction with
FIG. 9.
[0035] FIG. 5 shows lower mold assembly 31 fully engaged within
lower fixture 27. In this configuration, electrical connectors
60a-60d are joined to mating connectors on rear ends 61a-61d of
heating elements 50a-50d. As in FIGS. 3 and 4, other portions of
the system are omitted. FIG. 6 is a left side perspective view of
lower mold assembly 31 when fully engaged within lower fixture 27.
Other portions of the system have also been omitted from FIG.
6.
[0036] FIG. 7 is a lower perspective view of upper mold assembly 30
secured in upper fixture 26, and with other components of the
system omitted. As with lower mold assembly 31 and lower fixture
27, upper mold assembly 30 includes a carrier tray 65. Although not
included in the embodiment of FIG. 7, carrier tray 65 could also
include a handle similar to handle 45 (see FIG. 4). Carrier tray 65
has an outer shape that fits within, and generally corresponds to,
inside surfaces 66a-66c of upper fixture 26 (see FIG. 8). Upper
mold assembly 30 is retained within upper fixture 26 so that upper
mold assembly 30 remains in position when lower clamp plate 23 is
moved downward and the mold assemblies 30 and 31 are no longer
engaged. Upper mold assembly 30 is secured within upper fixture 26
by brackets 67 (only brackets 67 on left side wall 69 are visible
in FIG. 7). Each bracket 67 is bolted on a side wall 69 of upper
fixture 26 so that an ear 68 extends over a side wall 70 of carrier
tray 65. The upper mold assembly can be secured within the upper
fixture in numerous other manners. In some embodiments, for
example, tongues formed on the sides of the upper tray slide into
(and are held within) grooves formed in the inside surfaces of the
upper fixture side walls.
[0037] FIG. 8 is similar to FIG. 7, but with upper mold assembly 30
removed. Similar to lower fixture 27, upper fixture 26 includes a
bracket 75 having electrical connectors 76a-76d. When upper mold
assembly 30 is installed in upper fixture 26 (as shown in FIG. 7),
connectors 76a-76d are respectively attached to mating connecters
on rear ends (not shown) of heating elements 51a-51d. Electrical
power is supplied to heating elements 51a-51d through connectors
76a-76d. Additional details of heating element operation are
provided below. Bracket 75 includes a flange 77 having a front edge
78. When upper mold assembly 30 is placed in upper fixture 26,
front edge 78 abuts the rear side of carrier tray 65 and prevents
upper mold assembly 30 from sliding any further to the rear. In
this manner, front edge 78 and the inside surfaces 66a, 66c of side
walls 69 laterally position upper mold assembly 30 for a molding
operation.
[0038] FIG. 9 is a front perspective view of lower mold assembly 31
with mold 34 removed to reveal additional details of the
arrangement of various elements within assembly 31. As previously
indicated, molds 34 (not shown in FIG. 9) and 35 have cavities 80
and 81. Surfaces of cavities 80 and 81 correspond to the lower
surfaces of outsoles being molded. Molds 34 and 35 may be formed
from steel, aluminum or other type of metal conventionally used for
compression molds. Heating elements 50a-50d are situated directly
under mold elements 34 and 35. In the embodiment shown, each of
heating elements 50a-50d is an electrically powered cartridge
heater. Cartridge heaters, which are well known and commercially
available from numerous sources, generate heat when supplied with
electric power. Each of heating elements 50a-50d receives power
through an electrical connector (not shown) on its respective rear
end 61a-61d. The connectors on rear ends 61a-61d join to connectors
60a-60b (see FIG. 6). In at least some embodiments, each cartridge
heater includes a female two-lead connector, and each of connectors
60a-60b is a two-lead male connector. As with cartridge heaters,
such connectors are well known and available from numerous sources.
In other embodiments, however, electrical power is provided to the
heating elements in other manners. As but one example, each of the
heating elements may have two exposed terminals at its rear end.
Individual electrical wires are connected to those terminal with
alligator clips, by bolting of wire ends onto terminal posts, or in
some other manner.
[0039] In the embodiment of FIG. 9, and as previously described,
connectors on ends 61a through 61d are joined to connectors 60a-60d
when mold assembly 31 is slid into position within lower fixture
27. Connectors 60a through 60d (see FIGS. 4-6) are in turn wired to
a power supply. A rheostat or similar device (not shown) can be
used to adjust the amount of power provided to the heating elements
via connectors 60a through 60d, and thus adjust the amount of heat
produced by the heating elements.
[0040] Lower mold assembly 31 further includes conductor plates 84.
In at least some embodiments, conductor plates 84 are formed from
brass, bronze or some other material having a heat conductivity
value which is higher than that of molds 34 and 35. This permits
heat from the heating elements 50a through 50d to be spread more
evenly and more quickly across the molds. In the embodiments shown,
the heating elements are cylindrical in shape. Half-round recesses
are formed in conductor plates 84 and in the outer surfaces of
molds 34 and 35 to hold the heating elements and to place the outer
surfaces of the heating elements in direct contact with the
conductor plates and the molds. In other words, the shapes of the
half round recesses and of the heating elements are complementary.
The half-round recesses can be cast into molds 34 and 35 (using,
e.g., methods similar to those described in provisional U.S. patent
application 60/644,512, filed Jan. 19, 2005 and incorporated by
reference herein). The recesses could alternately be milled or
formed in some other manner.
[0041] As further shown in FIG. 9, a locator 49 is positioned
between heating elements 50a and 50b. Locator 49 is cylindrical and
rests within a complementary half-round recess in conductor plate
84. A complementary half-round corresponding to locator 49 is also
formed in the outer surface of mold 34. A similar locator is
positioned between heating elements 50c and 50d, and rests within
complementary recesses in mold 35 and in the conductor plate 84
under mold 35. These locators, which may be simple metal rods,
serve to correctly position molds 34 and 35 relative to conductor
plates 84 and prevent the molds and conductor plates from sliding
relative to one another along the length of the heating elements.
In other embodiments, locators may be formed in a different manner
(e.g., a stub formed on a mold and a corresponding depression
formed on a conductor plate) or omitted.
[0042] FIGS. 10A-10C show alternate manners in which the heating
elements may be arranged with regard to other portions of a mold
assembly. Each of FIGS. 10A through 10C is a transverse cross
section of a mold, conductor plate(s) and heating elements. In FIG.
10A, heating elements 220 rest within recesses 221 such that the
upper surfaces 222 of heating elements 220 are in contact with the
outer surface of the mold, but with almost all of the heating
elements inside of recesses 221. Although potentially less
thermally efficient than the arrangement of FIG. 9, the arrangement
of FIG. 10A does not require recesses in the mold. In FIG. 10B,
heating elements 220 are placed between two vertically-superimposed
conductor plates, with each of those conductor plates having
complementary half-round recesses 221' formed therein. In FIG. 10C,
heating elements 220' having square cross sections are used. In
each of the arrangements of FIGS. 10A-10C, locators between the
conductor plate and the mold (and/or between the conductor plates
in FIG. 10B) can be included.
[0043] Returning again to FIG. 9, lower mold assembly 31 also
includes layers of insulating material 86 between conductor plates
84 and carrier tray 55. In at least some embodiments, insulating
material 86 is formed from a material having a thermal conductivity
value which is lower than the thermal conductivity value of the
material from which carrier tray 55 is formed. Examples of
materials which can be used for insulating material 86 include
glass-reinforced polymer composite insulator sheets available from
D-M-E Co. of Madison Heights, Mich. and the product sold under the
name GLASTHERM by Monoco, Inc. of Grand Rapids, Mich. Insulating
material 86 (which can be, e.g., approximately 0.25 inches thick)
permits more of the heat from the heating elements to be directed
to molds 34 and 35.
[0044] Molds 34 and 35, heating elements 50a-50d, locators 49,
conductor plates 84 and layers of insulating material 86 are held
in place with brackets 87 and 88. FIG. 11A is a cross-section of
lower mold assembly 31 taken from the location shown in FIG. 9, and
with mold 34 included. As seen in FIG. 11A, molds 34 and 35 include
flanges 89 formed along their sides. For purposes of drawing
simplification, flanges 89 are not depicted in other drawing
figures. As with the half-round recesses in molds 34 and 35
previously described in connection with FIG. 9, flanges 89 can be
cast into molds 34 and 35 or formed by milling or other technique.
Brackets 87 are bolted to side walls 54 of lower carrier tray 55.
Each bracket 87 includes an ear 90 which retains a flange 89.
Brackets 88 are bolted to center divider 53, and include ears 91
which retain flanges 89.
[0045] In other embodiments, the components of a mold assembly are
secured together in other manners. For example, bolts could be used
instead of brackets such as brackets 87 and 88 in FIG. 11A. FIG.
11B is a cross section of a lower mold assembly according to
another embodiment, and taken from a location similar to that shown
in FIG. 9. Similar components in FIGS. 11A and 11B have similar
reference numbers, but include an added apostrophe (e.g., mold
assembly 31' in FIG. 11B vs. mold assembly 31 in FIG. 11A). In the
embodiment of FIG. 11B, bolts 230 are inserted through countersunk
holes 231 in tray 55'. Bolts 230 pass through corresponding holes
in insulating material layers 86' and conductor plates 84', and
engage threads in corresponding holes in molds 34' and 35'.
[0046] Returning to FIG. 7, upper mold assembly 30 includes
conductor plates 92 and layers of insulating material 93 which are
substantially the same as conductor plates 84 and layers insulating
material 86 of lower mold assembly 31. Upper molds 32 and 33,
heating elements 51a-51d, locators (not shown) similar to locators
49, conductor plates 92 and layers of insulating material 93 are
arranged in the same manner as like elements in lower assembly 31.
Brackets (not shown) similar to brackets 87 and 88 of FIG. 12 are
used to hold together the components of upper mold assembly 30. In
other embodiments, the components of the upper mold assembly are
secured in other manners (e.g., using bolts similar to the
embodiment shown in FIG. 11B). Heating elements 51a-51d operate in
a manner similar to the heating elements of lower mold assembly 31
(as previously described in connection with FIG. 9). In particular,
connectors 76a through 76d (FIG. 8) are wired to an electrical
power supply. Electrical power is supplied via connectors 76a-76d
to corresponding connectors on the ends (not shown) of heating
elements 51a through 51d, which causes the heating elements in
upper mold assembly 30 to produce heat.
[0047] As previously indicated, mold element 32 includes a
protrusion 94 which fits within cavity 80 of mold 34, and which
corresponds to the upper surface of a left shoe outsole. Mold 33
includes a protrusion 95 which fits into cavity 81 of mold 35, and
which corresponds to the upper surface of a right shoe outsole.
Molds 32 and 33 are also formed from steel, aluminum or other type
of metal conventionally used for compression molds.
[0048] In other embodiments, the number and positions of heating
elements under each mold is different. For example, molds for
certain outsoles (or other shoe components) may require additional
heat (or less heat) in certain regions. By way of illustration, a
region of a mold may have a disproportionately larger mass of metal
than is contained in other regions of the same mold. In order to
evenly heat that mold to a desired temperature, additional and/or
higher output heating elements may be needed in the regions having
more metal mass. FIG. 12 shows a conductor plate 84'' and a
plurality of heating elements according to at least one alternate
embodiment. Conductor plate 84'' is positioned between a mold (not
shown) and an insulating material layer (also not shown) in a
manner similar to that of conductor plate 84 in FIGS. 3-5, 9 and
11A. Conductor plate 84'' may be of a one piece design (e.g., as in
FIGS. 10A and 10C) or of a multipiece design (e.g., as in FIG.
10B). As can be appreciated, the embodiment of FIG. 12 permits
adaptation of a molding system in order to accommodate differing
internal mold geometries. In FIG. 12, heating elements 200a and
200b (separated by locator 207, which may alternately be omitted)
are cartridge heaters similar to heating elements 50a-50d of FIG.
9, and have a relatively high heat output. Heating element 201 is a
flexible heating element or a specially fabricated heating element
which is similar to cartridge heaters previously discussed, but
having the shape shown and a lower heat output. Heating element 201
is supplied with electrical power through electrical pathways
(e.g., thermally and electrically insulated wires) 202. Heating
elements 200a and 200b are supplied with electrical power through
connectors on the ends of elements 200a and 200b extending beyond
the end of conductor plate 84''. As seen by comparing FIG. 12 with
FIG. 9, the locations of power connections for the heating elements
of FIG. 12 is different than for the arrangement of FIG. 9.
Accordingly, bracket 57 of lower fixture 27 (see FIG. 4) could be
replaced with a different bracket having electrical connectors in
the proper locations for the arrangement of FIG. 12. Heating
element 201 may also have differing electrical power requirements
than heating elements 200a and 200b, and/or the may require a
different type of electrical connector hardware. A replacement
bracket could similarly be equipped with differing types of
connector hardware.
[0049] The embodiment of FIG. 12 is but one example of a manner in
which the number and positions of heating elements can be varied.
As but another example, a spiral coil or other shape of heating
element can be can be used in conjunction (with or instead of)
cartridge heaters.
[0050] As can be appreciated, the above-described embodiments offer
significant advantages over conventional compression molding
arrangements, particularly with regard to molding footwear
components. When molding large numbers of different types of
articles (e.g., components for different styles and/or sizes of
shoes), a large number of different molds are used. Some of these
molds may have differing heating requirements because of, e.g.,
different mold geometries. Instead of attempting to adapt press
platens to those different requirements, which may be difficult,
separate mold assemblies (with separate heating element
configurations) can be prepared for some or all of those molds.
[0051] Yet another advantage of at least some embodiments is shown
in FIGS. 13A-13E. In FIGS. 13A-13E, a sequence of operations (using
mold assemblies such as those described in connection with FIGS.
2-12) is shown. In the operations shown in FIGS. 13A-13E, there are
multiple lower mold assemblies 31(1) and 31(2). Each of those lower
mold assemblies mates with a single upper mold assembly 30.
Although upper mold assembly 30 is not clearly shown in FIGS.
13A-13E, it is the same as upper assembly 30 described previously.
Lower mold assemblies 31(1) and 31(2) are both the same as mold
assembly 31 described previously, with a "(1)" or "(2)" suffix
added to distinguish between the two lower assemblies.
[0052] Beginning in FIG. 13A, an operator has already prepared
lower mold assembly 31(1) by placing the raw materials in the
proper locations within cavities 80(1) and 81(1) of molds 34(1) and
35(1). Lower mold assembly 31(1) was then slid along conveyors 40
and 41 into lower fixture 27. The connectors (not shown) on the
rear ends of heating elements 50a(1)-50d(1) were attached to
electrical connectors 60a-60d (not shown in FIG. 13A), and
electrical power supplied to the heating elements of lower mold
assembly 31(1) to heat molds 34(1) and 35(1). Upper molds 32 and 33
of upper assembly 30 are likewise heated by heating elements in
upper assembly 30 (in some embodiments, a switch may be used to
remove power from the upper molds between molding operations).
Lower clamp plate 23 is then moved upward to engage the upper mold
assembly 30 with lower mold assembly 31(1) (FIG. 13B).
[0053] Once clamp plate 22 and 23 are pressed together, they remain
in that condition for a predetermined amount of pressing time. In
some cases, and depending upon the product being molded and/or the
materials being used, this pressing time may be significant
(several minutes or more). During this time, the operator may
multitask and place raw materials in the proper locations within
cavities 80(2) and 81(2) of molds 34(2) and 35(2) of lower mold
assembly 31(2). After the appropriate mold pressing time, and as
shown in FIG. 13C, lower clamp plate 23 is lowered. Lower mold
assembly 31(1) is then removed from lower fixture 27 (FIG. 13D),
and lower mold assembly 31(2) is moved into position within lower
fixture 27 (FIG. 13E). Electrical connections are made to heating
elements 50a(2)-50d(2), thereby causing molds 34(2) and 35(2) to be
heated. At this stage, lower clamp plate 23 can be moved toward
upper clamp plate 22 to press mold assemblies 31(2) and 30
together, and the operator can begin preparing the next lower mold
assembly. In some cases, the operator may simply remove the
just-molded components from lower mold assembly 31(1) and begin
preparing lower mold assembly 31(1) for the next pressing. In other
cases, there may be multiple additional lower mold assemblies.
[0054] Numerous other variations on the systems and operations
described above will be apparent to persons skilled in the art in
view of the description and drawings provided herein. As previously
indicated, the invention is not limited to use in conjunction with
molds for a particular type of article. The invention is similarly
not limited to molds having geometries such as are shown in the
drawings. In some cases, for example, the molds which join to
create a mold volume will not include a protrusion on one of those
molds. Instead, all of the molds may have a depression formed
therein. The invention is also not limited to use in conjunction
with systems where only two molds are joined to create a mold
volume. As but one example, three molds could be configured so that
those molds fit together to define a mold volume. Other types of
heating elements could also be used, including elements which are
powered by a source other than electricity. Other manners of
attaching various components can be employed. As but one
illustration thereof, peening could be employed (e.g., hammering a
conductor plate, heating element, mold and/or tray to slightly bend
the metal and retain other components). These and other variations
and permutations of the above described devices and operations fall
within the spirit and scope of the invention as set forth in the
appended claims. It is to be understood that the subject matter
defined in the appended claims is not necessarily limited to the
specific features or acts described above. Rather, the specific
features and acts described above are disclosed as example forms of
implementing the invention as set forth in the claims.
* * * * *