U.S. patent application number 13/693255 was filed with the patent office on 2013-04-18 for floor tile with overmold crush pads.
This patent application is currently assigned to MacNeil IP LLC. The applicant listed for this patent is MacNeil IP LLC. Invention is credited to David S. IVERSON, Thomas MALEWIG, Frederick W. MASANEK, JR., Allan R. Thom.
Application Number | 20130095295 13/693255 |
Document ID | / |
Family ID | 48086176 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130095295 |
Kind Code |
A1 |
MASANEK, JR.; Frederick W. ;
et al. |
April 18, 2013 |
FLOOR TILE WITH OVERMOLD CRUSH PADS
Abstract
A modular plastic floor tile has a body of a first polymer
compound and at least one skin overmolded onto the support member
core from a second polymer compound. The compounds may be different
from each other in hardness and/or color. Crush pads are formed
from the first polymer and are disposed to be below the general
lower surface of the tile. The crush pads provide a tight overmold
shutoff and prevent flashing of the second polymer compound when
the support member is formed.
Inventors: |
MASANEK, JR.; Frederick W.;
(Barrington, IL) ; MALEWIG; Thomas; (Sugar Grove,
IL) ; IVERSON; David S.; (Chicago, IL) ; Thom;
Allan R.; (Clarendon Hills, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MacNeil IP LLC; |
Bolingbrook |
IL |
US |
|
|
Assignee: |
MacNeil IP LLC
Bolingbrook
IL
|
Family ID: |
48086176 |
Appl. No.: |
13/693255 |
Filed: |
December 4, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12609959 |
Oct 30, 2009 |
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13693255 |
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PCT/US10/54515 |
Oct 28, 2010 |
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12609959 |
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12609959 |
Oct 30, 2009 |
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PCT/US10/54515 |
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13217556 |
Aug 25, 2011 |
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12609959 |
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Current U.S.
Class: |
428/161 |
Current CPC
Class: |
E01C 2201/12 20130101;
E04F 2201/021 20130101; Y10T 428/24521 20150115; E01C 5/226
20130101; E04F 2201/0146 20130101; E04F 15/02161 20130101; E04F
15/02172 20130101; E01C 2201/16 20130101; E01C 13/045 20130101;
E04F 15/02194 20130101; E04F 15/105 20130101 |
Class at
Publication: |
428/161 |
International
Class: |
E04F 15/02 20060101
E04F015/02 |
Claims
1. A modular floor tile for use in creating a flooring surface
comprising a plurality of such tiles, the floor tile comprising: a
body molded of a first polymer compound, the body including a
substantially planar, horizontal web having an upper surface and a
lower surface including a general lower surface; at least one
support member formed to be disposed below the general lower
surface of the horizontal web, at least some of said at least one
support member overmolded from a second polymer compound which,
when molded and solidified, is softer than the first polymer
compound when the first polymer compound is molded and solidified;
a crush pad formed to be laterally adjacent and to laterally
surround said at least one support member, the crush pad having a
smooth horizontal surface which is lower than the general lower
surface of the horizontal web, such that when at least some of said
at least one support member is overmolded with the second polymer
compound, the crush pad will provide a tight overmold shutoff and
will prevent flashing of the second polymer compound.
2. The floor tile of claim 1, wherein said at least one support
member is one of a group of support members each formed to
downwardly depend from the general lower surface of the horizontal
web, at least some of each support member in the group being
overmolded with the second polymer compound, the crush pad
laterally surrounding all of the support members in the group.
3. The floor tile of claim 1, wherein an entirety of the top
surface of the tile body is molded from the first polymer
compound.
4. The floor tile of claim 3, wherein a general upper surface of
the body has a plurality of spaced-apart upstanding features, for
each upstanding feature, at least one of the support members being
in approximate registration with the last said feature, such that
load on the upper surface experienced by the feature may be at
least partially transmitted to the respective support member.
Description
RELATED APPLICATIONS
[0001] This application is a continuation in part of copending U.S.
patent application Ser. No. 12/609,959 filed Oct. 30, 2009, and
further is a continuation in part of copending International Patent
Application No. PCT/US10/54515 filed Oct. 28, 2010, which in turn
is a continuation in part of pending U.S. patent application Ser.
No. 12/609,959 filed Oct. 30, 2009. The present application is
further a division of pending U.S. patent application Ser. No.
13/217,556 filed Aug. 25, 2011. All of the foregoing applications
are owned by a common assignee. The specifications and drawings of
each of them are fully incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] Conventional modular injection-molded tiles are known in the
art for laying across upper surfaces of garage floors, sports
surfaces, outdoor surfaces and other substrates. These tiles
typically are twelve to thirteen inches square and can be manually
assembled and disassembled. A common feature of these tiles is
their ability to be snapped together, with few or no tools, using
male and female connectors molded into each tile for the
purpose.
[0003] Conventional single tiles are molded to be a single, uniform
color such as all-black or all-red. The consumer typically can
choose different tiles in different colors. The consumer or
contractor will often choose two or more colors for a particular
floor, for assembly into an aesthetically pleasing pattern. But
manufacturing an injection-molded plastic tile that has two or more
perceptible colors per tile is more difficult and to date no such
tile has been provided that has proven to be acceptable to the
consumer.
[0004] Many conventional modular plastic tiles are easily dislodged
from their positions on the floor (particularly where wheeled
vehicles are driven onto and off of them) and require a rubber
sheet or the like as a substrate. It would therefore be
advantageous to furnish a floor tile, for applications in which a
large displacing lateral force may be applied to the tile, and
which does not require a nonslip sheet as a substrate.
[0005] Previous attempts have been made to produce plastic modular
tiles that have cushioning characteristics. U.S. Patent Application
Publication No. US 2009/0031658 A1 discloses modular athletic floor
tiles that have a plurality of premolded rubber inserts which,
after molding, are physically inserted into receiving holes in a
molded plastic substrate. In one embodiment each rubber insert has
a face that is stands up from the surrounding top floor surface.
The body of each rubber insert extends all the way through the
plastic substrate or base and well below its bottom. The rubber
inserts are selectively compressed when an athlete stands on them,
giving a cushioning effect. But it is believed that the separate
molding of these inserts, flash removal from them and physical
insertion of them into respective receiving holes in the plastic
tile substrate is time-consumptive and greatly increases the cost
of manufacture of the resultant tile.
[0006] A need therefore persists in the industry for modular
plastic tiles which can sustain heavy loads but have non-slip
characteristics, which will be effectively joined together, which
can be provided in a plurality of colors per tile, and which can be
manufactured quickly and inexpensively.
SUMMARY OF THE INVENTION
[0007] According to one aspect of the invention, a modular floor
tile is provided which may be used to create a flooring surface
including a plurality of like tiles. A first polymer compound is
used to mold a body of the tile. The body has at least one feature
overmolded onto the upper surface of the body from a second polymer
compound which is different from the first polymer compound. A
second polymer compound gate is disposed to be adjacent a lower
surface of the tile body and to be remote from the upper surface
thereof. The gate communicates to the upper feature through a
through-hole which extends from the lower surface to the upper
surface. A vent hole, laterally spaced from the through-hole,
extends from the upper surface back to the lower surface and is in
communication with the upper feature. During the injection of the
second polymer compound, molten polymer makes its way from the
gate, through the through hole and into the cavity in which the
upper feature will be created. The vent hole permits gas or other
fluid to be displaced out of the upper feature cavity, thereby
obviating or minimizing any void in the as-molded upper feature
which might otherwise occur. In one embodiment a portion of the
upper pad extends through the vent hole to be disposed below or
protrude onto the lower surface. Preferably, the tile has many such
pads on its upper surface, and many such support members downwardly
depending from its lower surface. Groups of these pads and support
member portions may be molded together in a continuous phase of the
second polymer compound.
[0008] The second polymer compound may differ from the first
polymer compound in rigidity, coefficient of friction, color, or
some or all of these, and in one embodiment the upper feature
constitutes a nonslip pad. In one embodiment a spaced-apart
plurality of such upper features are formed as connected to one
gate, through a plurality of through-holes, with at least one vent
hole accorded to each of the upper features. In one embodiment the
vent hole is laterally positioned to be maximally spaced from the
through hole and still be within the periphery of the upper
feature. In one embodiment the periphery of the upper feature is
defined by a smoothly finished crush ring which prevents flash of
the second polymer compound.
[0009] In another aspect of the invention, a modular floor tile has
a body molded of a first polymer compound, the body including a
substantially planar horizontal web with an upper and a lower
surface. The floor tile further includes at least one lower feature
overmolded onto the lower surface of the tile body from the second
polymer compound. The lower feature may, for example, be a "skin"
overmolded over a support member core which is disposed below the
general lower surface of the horizontal web, the skin and core
constituting a support member. A crush pad is formed completely
laterally around the lower feature. The crush pad is smooth and is
disposed blow the general lower surface of the tile body. The crush
pad prevents flash from the molten second polymer compound during
the overmolding step.
[0010] There may be a plurality of such lower features, all
connected to a single gate. In one embodiment, groups of upper
features and associated lower features all connect to respective
fill points or gates, with the tile having a plurality of these
groups.
[0011] In a further aspect of the invention, a method of forming a
plastic modular floor tile includes molding a body of a first
thermoplastic polymer compound, and then overmolding the body using
a second polymer compound that has different characteristics from
the first, such as differences in rigidity, coefficient of friction
and/or color. The step of overmolding includes the substeps of
positioning a gate adjacent the lower surface of the tile body and
remote from an upper surface thereof; flowing polymer from the gate
through a vent-hole to form an upper feature on the upper surface;
and displacing a fluid (such as a gas) out of the volume of the
upper feature cavity through a vent hole extending from the upper
surface to the lower surface thereof, thereby minimizing or
obviating any void which might otherwise appear in the upper
feature as molded.
[0012] In one embodiment, the method further includes flowing the
molten second polymer compound from the gate, by a path which does
not pass through the tile body, to a lower feature which is
overmolded on the lower surface of the body. The method may also
include the step of flowing molten second polymer compound through
the vent hole such that a portion thereof protrudes onto the lower
surface of the tile body. In this last instance the method further
preferably includes spacing such portion from the lower feature as
by a crush pad, so that the flow of polymer creating the lower
feature won't conflict with the flow of polymer creating the upper
feature, and so that any gas or fluid will be positively displaced
from the upper surface through the vent hole. In one embodiment,
groups of upper and lower features are each formed from polymer
flowing from a single respective gate or fill point. The method may
be used to overmold nonslip pads on the tile upper surface and, in
one embodiment, to simultaneously overmold support member nonslip
skins on the lower surface of the tile.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] These and further aspects of the invention and their
advantages can be discerned in the following detailed description,
in which like characters denote like parts and in which:
[0014] FIG. 1 is an isometric view of four modular floor tiles
according to the invention, as assembled into a portion of a
flooring surface;
[0015] FIG. 2 is a front isometric view of one of the modular floor
tiles shown in FIG. 1;
[0016] FIG. 3 is a back view of the modular floor tile shown in
FIG. 2;
[0017] FIG. 4 is an isometric detail of the back of the floor tile
shown in FIG. 3, illustrating a tile body prior to overmolding with
a second polymer compound;
[0018] FIG. 5 is an isometric detail of the same tile region shown
in FIG. 4, shown after overmolding has been completed;
[0019] FIG. 6 is a detail of the upper surface of a tile according
to the invention prior to overmolding, showing flow-through points
and crush rings;
[0020] FIG. 7 is a detail of the same region illustrated in FIG. 6,
shown after top surface pads have been overmolded;
[0021] FIG. 8 is a magnified sectional detail of two adjoining
tiles showing internal structure of the support members;
[0022] FIG. 9 is a magnified sectional detail of a tile showing the
relationship of the overmolded features on the tile's lower and
upper surfaces;
[0023] FIG. 10 is magnified bottom view detail of a tile according
to the invention;
[0024] FIG. 11 is a magnified sectional view of two tiles being
assembled together;
[0025] FIG. 12 is a magnified sectional view of two joined tiles
taken through cooperating loop and latch structure;
[0026] FIG. 13 is a diagram showing nonlinear interference between
a latch and a loop according to the invention;
[0027] FIG. 14 is a schematic flow diagram illustrating steps in a
manufacturing process according to the invention;
[0028] FIG. 15 is an isometric magnified detail view of a corner of
a tile body according to a second embodiment of the invention,
prior to overmolding a peripheral seal thereon;
[0029] FIG. 16 is the tile body corner seen in FIG. 15, after
overmolding;
[0030] FIG. 17 is a magnified sectional detail through a lateral
edge of the tile illustrated in FIG. 16;
[0031] FIG. 18 is a magnified sectional detail showing joined
lateral edges of adjacent tile, taken through two cooperating
peripheral seals;
[0032] FIG. 19 is a schematic isometric view of a tile according to
a third embodiment of the invention, wherein a second polymer
compound is injected into a gate on an upper surface of the
tile;
[0033] FIG. 20 is a top isometric view of a modular floor tile
according to a fourth embodiment of the invention;
[0034] FIG. 21 is a magnified sectional view of two tiles according
to a fifth embodiment of the invention;
[0035] FIG. 22 is a magnified sectional view of the two tiles shown
in FIG. 21, taken through cooperating latch and loop structure;
and
[0036] FIG. 23 is a back view of a modular floor tile according to
another embodiment;
[0037] FIG. 24 is an isometric detail of the back of the floor tile
shown in FIG. 23, illustrating the tile body prior to overmolding
with a second polymer compound;
[0038] FIG. 25 is an isometric detail of the same tile region shown
in FIG. 24, shown after overmolding has been completed;
[0039] FIG. 26 is a detail of the upper surface of the tile shown
in FIG. 23 prior to overmolding, showing through-holes, vent holes,
and crush rings;
[0040] FIG. 27 is a magnified sectional detail of the tile shown in
FIG. 23, showing the relationship of the overmolded features on the
tile's upper and lower surfaces; and
[0041] FIG. 28 is a schematic flow diagram illustrating steps in an
alternative manufacturing process according to the invention.
DETAILED DESCRIPTION
[0042] Modular floor tiles according to the invention can be used
to form a flooring surface, a representative portion 100 of which
is shown in FIG. 1. In this illustrated embodiment, the flooring
surface 100 is made up of tiles 102, including first floor tiles
102A and second floor tiles 102B, which are identical except as to
color. The floor tiles 102A each have a body 104 injection-molded
from a first polymer compound, preferably comprising a polymer
which is relatively rigid when solidified and which can be selected
from the group consisting of polyolefins including polypropylene
and high molecular weight polyethylene, rigid thermoplastic
polyurethane (TPU), acrylonitrile butadiene styrene (ABS) and rigid
polyvinyl chloride (PVC). The first polymer compound may further
include filler such as talc to aid in achieving surface flatness,
and a pigment. Floor tiles 102B have bodies 104 which preferably
are made of a polymer compound identical to that forming bodies 104
of tiles 102A, except possibly for the choice of pigment or
colorant. Each floor tile 102 preferably has an array of features
106, or raised pads, on its upper surface 108. The pads 106, which
preferably are spaced apart on the upper surface 108, are
overmolded onto the upper surface 108 using a second polymer
compound, which has different characteristics from the first.
[0043] The differences between the first and second polymer
compounds can include color and/or hardness. In one embodiment the
second polymer compound, once solidified, is softer or less rigid
than the first (once solidified), and has a higher coefficient of
friction with respect to most objects than does the first. In
another embodiment the hardness of the first and second compounds
(once solidified) is about the same, but the colors are distinctly
different. In a third embodiment, the hardness (once solidified) of
the second compound is greater than that of the first. In a
preferred embodiment, the second polymer compound can be selected
from the group consisting of styrene ethylene butylene styrene
based thermoplastic elastomer (SEBS TPE), other TPEs, soft TPU, or
soft PVC. Polypropylene as the principal polymer in the first
compound, and SEBS TPE as the principal polymer in the second
polymer, are particularly preferred and have demonstrated good
adherence to each other.
[0044] One aesthetic advantage of the invention is that the first
and second polymers can be provided in contrasting colors, and that
because of the molding techniques used in the invention, pads 106
can be colored differently than upper surface 108 yet present a
sharp, commercially acceptable appearance.
[0045] A top isometric view of one tile 102 is shown in FIG. 2. The
body 104 of tile 102 is in main part a substantially horizontal and
planar web 200 that has a plurality of lateral edges 202, 204. Each
of the web edges 202, 204 downwardly depends from the upper surface
108 to a lower surface (not shown in FIG. 2). In the embodiment
illustrated in FIG. 2, edges 202, 204 are orthogonal to surface
108, are planar and are at right angles to each other. But the tile
102, and the edges 202, 204 of it, can take other shapes. For
example, the tile 102 can be hexagonal or triangular, and the edges
202, 204 could be wavy or curved instead of straight. Instead of
edges 202, 204 being planar, as shown, they could be stepped or
have tongues and corresponding grooves (see FIGS. 15-16 for an
embodiment in which the lateral edges are stepped). It is
preferred, however, that the shape and profile of each web edge 202
be complementary to the shape and profile of each web edge 204,
such that when adjacent tiles are joined together, edges 202 and
204 will fit together closely.
[0046] The illustrated embodiment has a two-dimensional array of
sixty-four raised pads 106 as located on a square surface of about
twelve inches in length and width. Alternatively there could be as
few as one pad 106, which preferably would be larger and possibly
elongated and branched and/or sinuous. It is preferred to have a
regular pattern of the pads 106 so that sub-units of the tile 102
can be trimmed off of it, in a manner to be explained below, and so
that as trimmed the tile 102 will retain an aesthetically pleasing
appearance. The illustrated pads 106 are rounded squares but could
take other shapes such as circles, ovals, hexagons, triangles,
distinctive logos or other shapes.
[0047] The first edges 202 each are equipped with at least one, and
preferably several, latches 206. The second edges 204 each have at
least one, and preferably several, loops 208. It is preferred that
the number of latches 206, distributed in spaced relation along
first edge 202, equal the number and position of loops 208, which
are distributed in like spaced relation along each second edge 204.
In the illustrated embodiment the latches 206 are pressed downward
and snapped into loops 208, in a manner which will be described in
further detail below.
[0048] In the bottom view of tile 102 shown in FIG. 3, there can be
seen sixteen groups 300 of support members 302. According to one
aspect of the invention, each support member 302 is formed in part
by a skin 304 of a relatively soft polymer compound such as once
comprising TPE, and has a core that is molded as part of the body
104 from a polypropylene-based compound or other relatively rigid
polymer composition. Some of the support members 302 are annular
and take the shape of squares with empty centers. Other support
members 302 in each group 300 are short linear segments. The
support members will be discussed in further detail below.
Preferably the general lower surface 306 also has, depending
downwardly from it, a plurality of elongate rigid support ribs 308
that have no TPE or other soft polymer skin. The support ribs are
integrally molded with the web 200 of body 104.
[0049] In the illustrated embodiment, the rigid support ribs 308
form partial outlines of rounded squares, each one of which
contains one of the groups 300 of the support members 302. The
rigid support ribs 308 are so positioned that one or more of them
are not very far away from any group 300 of support members 302.
This permits the rigid support ribs 308 to accept most of the load
of heavy objects (such as vehicles) imposed on the upper surface
108 of tile 102.
[0050] The elongate ribs 308 also define and delimit linear
channels 310, one set of which are aligned along a length of the
tile 102, and another set of which are at right angles to these and
are aligned along a width of the tile 102. The channels 310 are
disposed between, rather than through, the support member groups
300 and (on the upper surface) the pads 106. This provides the
consumer a trim guide for cutting apart tile 102 in a lengthwise or
widthwise direction, or both, in predetermined increments such as
three inches or twenty-five percent of tile 102's length or width.
As projected onto the single horizontal plane occupied by web 200,
the center line of each channel 310 will substantially exactly
bisect the distance between the centers of adjacent pads 106 on
either side of the center line. The distance from the center line
of the channel 310 to a center of a pad 106 is one-half of the
distance from one center of a pad 106 to a next adjacent pad 106.
Since pads 106, support member groups 300, latches 206 and loops
208 repeat in a regular pattern, such as on three-inch centers, and
since the pads 106 are exactly twice as far apart from each other
as the closest of them are to the edge 202 and/or 204 (see FIG. 2)
or a channel 310, the consumer may use trimmed tiles on the
periphery of the flooring surface to extend the flooring surface by
another three, six or nine inches, or alternatively 25%, 50%, or
75% of the length or width of tile 102. The regular pattern and
spacing of raised pads 106 will continue over from untrimmed tiles
onto such trimmed peripheral tiles without visually noticeable
interruption and therefore the result will be aesthetically
pleasing.
[0051] FIGS. 4 and 5 are details of the tile lower surface, showing
a single group 300 of support members 302 before and after a second
polymer compound is overmolded onto the body 104 of the tile 102.
In FIG. 4 there can be seen a plurality of support member cores 400
which depend downwardly (in this view, extending toward the top of
the paper) from a general lower surface 306 of the substantially
horizontal web 200 that makes up most of the tile body 104. The
cores 400 do not downwardly depend as far as the support ribs 308.
Ribs 308 are not overmolded. In the illustrated embodiment there
are provided, in each group 300 of support members 302, four
annular cores 402 and eight cores 404 formed as short linear
segments and in parallel pairs nearby the annular cores 402. Also
seen here is, for this group 300, a crush pad 406 which in use is
slightly lower than the general surface 306 (in this bottom view,
pad 406 is slightly raised relative to general surface 306). The
crush pad 406 is formed to be closely adjacent all of the support
member cores 400 and laterally surrounds all of the cores 400 and
the runners 502 connecting the support members. The crush pad 406
is finished to have a smooth surface (general lower surface 306 can
instead be textured) and is used as a shutoff surface to prevent
the flashing of the second polymer compound during a "second shot"
or overmolding step of fabrication.
[0052] FIG. 5 shows the same area after overmolding. A skin 304 of
the second polymer now appears on the bottom surfaces and sides of
each of the cores 400, and in this embodiment completes the support
members 302. While in one embodiment the skins 304 could be
overmolded separately on each core 400, in the illustrated
embodiment the skins 304 within the support member group 300 are
part of a continuous phase. To save cost, the area covered by skins
304 is limited and, as seen in FIGS. 3 and 5, does not include a
majority of the tile body lower surface 306. The skins 304
preferably do not extend to cover the centers of the annular cores
402 or other regions outside of crush pads 406. Lateral runners 502
connect a common fill point 504 to each of the skins 304. It has
been found that as the second of a double-shot injection, skins 304
molded of a SEBS TPE compound have excellent adherence to the
preferably polypropylene compound cores 400 (FIG. 4). As completed,
the composite support members 302 are of approximately the same
depth (in a direction orthogonal to the web 200) as the support
ribs 308. The support members 302 provide further structural
support to the web 200 but at the same time act as a friction
surface to grip the surface upon which the tiles are laid.
[0053] FIGS. 6 and 7 are details of a similarly sized area on the
top of tile 102, before and after overmolding, illustrating one
group of pads 106, which are interconnected in a continuous phase
of solidified second polymer compound. In the illustrated
embodiment, each of the overmolded pads 106 resides in a shallow
recess or receptacle 600 whose surface is lower than that of the
general upper surface 108. For each recess 600 there is provided at
least one through-hole 602 which communicates the top surface of
the tile web 200 to a lower surface thereof. In the illustrated
embodiment the through-holes are a small fraction (about 5%) of the
bottom of the recesses 600, as the viscosity (at molding
temperature) of the preferred second polymer compound is low
enough, and the second-shot temperature and injection pressure are
high enough, that no larger through-holes are necessary to flow
molten polymer from the lower side of the tile body 104 to the
upper side thereof, nor is more than one through-hole per recess
600 necessary in the preferred embodiment. Limiting the size of
through-holes 602 enhances the structural integrity of the tile
102. However, in alternative embodiments, the size and/or number of
the through-holes 602 may be increased to accommodate more highly
viscous second-shot polymer compounds.
[0054] The recesses 600 are each laterally surrounded by a crush
ring 604. Each crush ring 604 is finished to be smooth (in
contrast, the general upper surface 108 of the body 104 is
preferred to be textured) and is slightly raised relative to the
general upper surface 108. The crush rings 604 provide a tight
overmold shutoff that prevents the flashing of the second polymer
compound outside the confines of the crush rings 604.
[0055] FIG. 7 is a detail of the tile upper surface after the
overmolding step. The second polymer compound is injected into the
mold at one or more points adjacent the lower surface of body 104,
flows through each of the through-holes 602, and occupies cavities
in the second-shot mold to create the raised pads 106. A top
surface of the pads 106 is raised above that of general surface
108, creating a nonslip surface characteristic. Through this
methodology overmolding artifacts on the upper surface of the tile
102 are avoided, producing a more pleasing appearance.
[0056] FIG. 8 is a sectional view of two tiles 102 joined together,
taken through annular support members 800, linear support members
802 and rigid ribs 308. Each skin 304 completing a support member
800, 802 has a portion 810 which is formed on the lower end or
bottom surface of each core 400, 402. Preferably, each skin 304
also includes portions 812 which cover all or portions of adjoining
side walls of the cores 400, 402.
[0057] The rounded square or annular support members 800 are each
in approximate registration or alignment with the edges or lateral
periphery of a respective raised pad 106 on the upper surface 108
of the tile 102. The support members 800 will receive any weight
placed particularly on the raised pads 106 and will prevent any
shear stress from developing in nearby regions of the horizontal
web 200. The support members 800 and 802 each help support weight
placed on the upper surface 108 of tile 102, while at the same time
providing a friction or nonslip surface that will engage the
substrate on which the tile is placed. The rigid members 308
provide rigid support of the entire tile 102 and delimit any
compression of the TPE skin 500, the lower surface of which is
preferably in the same plane as the lowest portion of ribs 308.
FIG. 8 also shows the preferred profile of lateral edges 202, 204,
which is planar and orthogonal to the plane of web 200. The
components of the adjacent tiles 102 in FIGS. 8 and 9 have been
stippled differently to illustrate that they can be of different
colors.
[0058] FIG. 9 is a magnified diagonal cross section (lower side up)
of part of a tile 102, taken through two raised pads 106, support
members 800 underneath and in approximate registry with respective
ones of the raised pads 106, a central fill point 504 and two
runners 502. In this illustrated embodiment, one central
second-shot polymer compound fill point 504 is provided for the
skins of an entire group 300 of twelve support members 800, 802,
and four associated raised pads 106 on the upper surface 108 of the
tile 102. This illustrated embodiment has sixteen fill points 504
on tile 102, one for each interconnected group 300 of support
members 302 and associated pads 106. In an alternative embodiment
the polymer compounds used for different ones of the fill points
could be in different colors, producing groups of pads 106 on the
upper surface 108 which are colored differently than other groups
of pads 106.
[0059] The central fill point 504 is connected by a set of runners
502 which extend laterally from the fill point 504, and on the
lower surface of the web 200, to each of the support members 800,
802 in the group 300 where the fill point 504 is located. In the
illustrated embodiment, there are four main runners 502 that are
separated by ninety degrees from each other. At its end remote from
the fill point 504, each runner 502 branches into three branches
900 that respectively connect to an annular support member 800 and
two flanking linear support members 802. As can be seen in the
sectioned runners 502, one of the branches 900 of each runner 502
is continuous with a through-hole 602, providing a conduit for the
second polymer compound to the upper side 108 of the tile 102.
[0060] FIG. 9 also shows a latch 206 which has been inserted into a
respective loop 208. The loop 208 is preferably molded as an
extension of a rigid rib 308 in an adjacent tile 102. The latch 206
is integrally formed with web 200 and is formed in a gap between
two ribs 308 that are adjacent an edge 202. The gap forming the
discontinuity in linearly aligned rib segments 308 is large enough
to have the latch 206 and the loop 208 disposed therebetween.
[0061] FIG. 10 is a bottom plan view of a one-sixteenth portion 998
of a tile 102, the illustrated portion 998 occupying an outer
corner of tile 102. This corner 998 has three ribs 308 that
surround the group 300 of support members 302. A rib segment 1000
is aligned with and positioned slightly laterally inwardly from an
edge 204 of the tile 102. Rib segment 1000 continuously curves on
its left side (as seen in this FIGURE) to form a boundary for a
channel 1002. Rib segment 1000 has a section 1004 which
continuously curves from the right side of rib section 1022 to
become parallel and laterally inwardly offset from lateral edge
202, terminating at a gap 1006. A rib segment 1008 defines an upper
right hand boundary of the portion or cell 998 and includes a
portion 1010 that is in parallel with the lateral edge 202, a
portion 1012 which helps define a boundary for a trim channel 1014,
and a curved portion in between these. A third rib segment 1016,
defining an interior corner of the cell 998, includes a portion
1018 that helps define channel 1002, a portion 1020 that helps
define channel 1014, and a curved transition between them.
[0062] A portion 1022 of the rib segment 1000 that is near and
parallel to lateral edge 204 has a loop 208 integrally formed with
it. The loop 208 is connected to the rest of tile 102 only by a
pair of widely spaced-apart and limited connection points 1024 and
1026. A cross-section of loop 208 and its length between connection
points 1024 and 1026 are so preselected that loop 208 will be
relatively flexible in comparison to the latch 206. The latch 206
may be a solid plug (not shown) or, as appears in the illustrated
embodiment, may include a downwardly depending, inwardly facing
convex wall 1028, connected at both of its ends to a downwardly
depending, laterally outwardly facing wall 1030. The entire wall
1028, and a substantial portion of the wall 1030, are attached to
the general lower surface 306 of the tile 102. Neither arcuate wall
1028 nor wall 1030 is as long as loop 208. These differences in
size and degree of attachment to the rest of the tile 102 make the
latch 206 substantially rigid relative to loop 208. In any
interference between them, therefore, the loop 208 will flex or
expand and the latch 206 will not substantially deform.
[0063] FIG. 11 is a highly magnified sectional view showing how a
male latch 206 is snapped into a receiving female loop 208 of an
adjacent tile 102. The outer wall 1030 of the latch 206 has a
surface 1100 which is beveled or sloped so that it will cam against
an upper corner 1102 of the lateral edge 204. The inner wall 1028
of the latch 206 has a sloped or beveled surface 1104 which will
cam against an upper interior corner or ridge 1106 of the loop 208.
As the latch 206 is pressed downward into the loop 208, an
interference will develop between the inner facing wall 1028 of the
latch 206 and the loop 208, as shown by the hatched region 1108.
Since wall 1028 of latch 206 is substantially more rigid than loop
208, the loop 208 will elastically expand along its length and will
flex laterally outwardly from the tile 102 to which it is attached
(in FIG. 11, rightward). Once the latch 206 is driven down far
enough, a horizontal ledge 1110 of the outer latch wall 1030 will
snap past a lower corner 1112 of the lateral edge 204 and will
slide to the left along the general lower surface 306 of the
adjacent tile 102. Even after this happens the loop 208 will remain
under tension. This biases lateral edge 204 against mating lateral
edge 202, producing a tight fit of these two surfaces and the tiles
of which they are a part. As shown, the depth (in a direction
orthogonal to the plane of web 200) of walls 1028, 1030 is slightly
less than the depth of the walls of rib segment 1022 and loop 208,
permitting a degree of overdrive when snapping the latch 206 into
the loop 208. FIG. 12 is an isometric sectional view of two
adjacent tiles taken through a loop 208 and an inserted latch 206,
again illustrating the interference fit between the two.
[0064] FIG. 13 is a schematic detail, from a bottom view, showing a
latch 206 as it is received into a loop 208. The loop 208 is
illustrated here in its unstretched and unflexed condition. As so
superimposed a region 1108 of interference will exist between loop
208 and an inner wall 1028 of the latch 206, and this region 1108
will be of variable depth as measured in a lateral inward/outward
direction. The inner wall 1028 has an inwardly-facing surface 1300
which has on it a point 1302 which is innermost and is farthest
away from the lateral edge 202 of body 104 (see FIGS. 11 and 12)
with which it is most closely associated. Preferably the
inwardly-facing surface 1300 is arcuate and convexly so relative to
the center of the tile 102. Surface 1300 can be more sharply curved
than is shown. As one travels away from the innermost point 1302
along the surface 1300 (to the left or right in this FIGURE), the
depth of interference region 1108 decreases, until the interference
region 1108 vanishes altogether as one approaches either end 1304,
1306 of the surface 1300. Preferably the inner surface 1308 of the
loop 208 is arcuately concave. More preferably the degree of
concavity of the inner surface 1308 is less than the degree of
convexity of the inward facing surface 1300 of the latch 206, that
is, the surface 1308 is more gradually curved than surface 1300. In
this way, the interference is minimized at the attachment points
1024, 1026, preventing the loop 208 from becoming over-stressed at
its attachment points 1024, 1026 and reducing the likelihood of
loop failure. It is relatively easy for loop 208 to stretch and
flex at its middle, opposite innermost latch wall point 1302, as
the length to either point 1026 or point 1024 is long. But the
resistance to such stretching and flexing will increase as one
approaches point 1024 or point 1026, as the points of attachment
are closer. Varying the degree of interference in the manner shown
therefore reduces the stress at the attachment points 1024, 1026.
The attachment points 1024, 1026 may be reinforced with gussets
2502 (see FIG. 25) to prevent loop breakage.
[0065] FIG. 14 is a schematic block diagram illustrating steps in a
floor tile manufacturing process according to the invention. Step
1400 is a mold design step including many substeps, of which three
are pertinent here. The mold (and the part produced thereby) should
have certain characteristics, and these include the provision of
flow-through holes at substep 1402. The flow-through holes are
positioned to communicate the recesses 600 for the pads 106 (see
FIG. 6), on the upper surface 108, to the central second polymer
compound fill points 504 adjacent the lower surface 306. The second
shot of polymer compound will use these flow-through holes (602 in
FIG. 9) to access the cavities 600 in which the pads 106 are to be
created. The size and number of through-holes 602 will be dictated
in part by the viscosity of the second polymer compound at molding
temperature, and the injection molding pressure to be used.
[0066] The designer also, at substep 1404, provides for crush rings
604 (FIG. 6) on the top surface 108 of the tile 102, and crush pads
406 (FIG. 8) on the bottom surface 306 of the tile 102. These
surfaces preferably are flat, smooth, and slightly raised or
outward in relation to the rest of the surfaces of which they are a
part. The crush rings 604 and crush pads 406 closely laterally
surround the regions into which the second polymer compound is to
flow, creating a clean shutoff of the second polymer compound and
preventing flashing. This is particularly important on the upper
surface 108 as it will affect the aesthetic acceptability of the
tile 102.
[0067] At substep 1406, the designer provides runners 502 (see FIG.
9) to communicate the central fill points 504 with the support
members 800, 802 and the through-holes 602. The result of step 1400
will be tooling that can be used in a two-shot injection molding
process according to the invention.
[0068] The mold is placed in an injection molding press and a first
shot of polymer compound is injected into the mold at step 1408. As
explained above, this first polymer compound is thermoplastic and
preferably is relatively rigid, and can comprise polypropylene.
Then, at step 1410, the mold is prepared for a second injection
shot, in which further molding structure is used to define surfaces
of pads 106, skins 304 and runners 502. A second shot of polymer
compound is then injected into the mold, using a second polymer
compound which has different characteristics than the first polymer
compound, such as being harder or softer or being of a different
color. Preferably the second polymer is elastomeric and for example
can be constituted by SEBS TPE or another TPE. A preferred result
of molding steps 1408 and 1410 is a composite floor tile which
includes a body capable of withstanding a large amount of weight
(such as might be imposed by a vehicle wheel) but still has nonslip
characteristics on both its upper and lower surfaces.
[0069] FIGS. 15-18 illustrate an embodiment of the invention in
which the overmolded structure includes a peripheral seal that is
used to seal to adjoining tiles when a floor surface is assembled.
FIG. 15 is an isometric view of a floor tile body 1500 that is
similar to body 104 (FIG. 2) but with lateral edges 1502, 1504 that
are stepped rather than orthogonal to the web 200 and planar. This
view is taken after molding the first polymer compound but prior to
overmolding. In this illustrated embodiment, stepped lateral edge
1502 has a laterally inwardly disposed vertical surface 1506 which
extends downwardly from general upper surface 108 to a horizontal
shelf 1508. The horizontal shelf extends laterally outwardly from
vertical surface 1506 to a second, laterally outwardly disposed
vertical surface 1510. Vertical surface 1510 extends from the shelf
1508 to the lower surface 306 of the tile body 1500.
[0070] In the illustrated embodiment a lateral edge 1504 is similar
in form to lateral edge 1502. A first, laterally inwardly disposed
vertical surface 1512 extends from general upper surface 108 of the
tile body 1500 to a shelf 1514. The shelf 1514 extends laterally
outwardly from the vertical surface 1512 to a second, laterally
outwardly disposed vertical surface 1516. The vertical surface 1516
extends from the shelf 1514 to the general lower surface 306 of the
tile body 1500. Surfaces 1506, 1508 and 1510 define a recess (more
particularly, a step) 1518 which can be subsequently occupied by an
overmolded peripheral seal. Similarly, surfaces 1512, 1514 and 1516
define a step 1520 which can be subsequently occupied by an
overmolded peripheral seal, preferably continuous with the seal
occupying step 1518. While this illustrated embodiment uses steps
1518, 1520 as locations which can be occupied by a peripheral seal,
other profiles are possible, such as curved or keyed profiles
and/or ones which include a physical interference to the
delamination of the peripheral seal from the body 1500. As before,
it is preferred to mold the body 1500 from a relatively strong and
rigid polymer compound such as one comprising polypropylene.
[0071] FIG. 16 shows the view shown in FIG. 15, but after at least
one overmolding step in which a peripheral seal 1600 has been
overmolded into the steps 1518, 1520 to laterally surround the body
1500. The creation of the seal 1600 can take place during, before,
or after the creation of the raised pads 106 and skins 304 (FIG.
9), and the seal 1600 can be constituted by a polymer compound
which is the same as or which is different from the polymer
compound constituting pads 106 and skins 304, in terms of
composition, hardness, and/or color. It is preferred that the seal
1600 be constituted by a compound comprising SEBS TPE or other
elastomeric compound.
[0072] A top surface 1602 of the seal 1600 is preferred to be
coplanar with the general surface 108 of the body 1500. On one side
of the tile body 1500, the horizontal surface 1602 extends from
vertical surface 1506 laterally outwardly to a vertical surface
1604 of the seal. The vertical surface 1604 of the seal extends
from seal horizontal surface 1602 until it meets with vertical
surface 1510 of the body 1500, with which it is coplanar. As better
seen in FIG. 17, the otherwise planar vertical surface 1604 is
interrupted by a bump 1606 which is convex in section.
[0073] On an adjacent side of the body 1500, a horizontal surface
1608, which is continuous with the surface 1602 and preferably
coplanar with upper surface 108 of body 1500, extends laterally
outwardly from the lateral edge of vertical surface 1512 to a
vertical surface 1610 of the seal 1600. The vertical surface 1610,
which in general is orthogonal to surface 108 and planar, is
interrupted by a convex bump 1612. Otherwise, surface 1610 meets
and is coplanar with vertical surface 1516 of the body 1500.
Surfaces 1604, 1610 form a ninety degree corner at their
junction.
[0074] As shown in FIG. 18, when adjacent tiles 1800 are assembled
such that a latch 206 is inserted into a loop 208, the bumps 1606,
1612 are in interference with each other, as shown by hatched
interference region 1614. This creates a substantially watertight
peripheral seal of each tile to the other tiles in the floor
surface.
[0075] A further embodiment of the invention is shown in FIG. 19,
in which certain structure adjacent the lower surface 306 of a tile
1900 is shown in phantom. This embodiment is similar to that shown
in FIG. 2, with the difference that the second shot of polymer
compound is introduced at upper surface 108 of the body 104, rather
than at lower surface 306 thereof. For each of a group 300 of pads
106 and skins 304, a gate 1902 is formed to extend from the upper
surface 108 of body 104 to the lower surface 306 thereof. The gate
1902 is continuous with runners 502 on the lower surface, which in
turn communicate with the skins 304, the through-holes 602 and the
cavities 600 in which are molded the pads 106. In making the
second-shot injection, the second polymer compound flows through
the gates 1902 to the lower surface 306, thence through runners 502
to the skins 304 and the through-holes 602, and finally back
through the body 104 to the cavities 600 to mold the pads 106. In
an alternative embodiment, the pads 106 are omitted and only
structure adjacent lower surface 306 is molded, except for dots on
the upper surface that result from the gates 1902.
[0076] It is possible to overmold certain features on the bottom
surface of the tile without creating raised pads from the second
polymer compound on the top surface thereof. A top surface of such
an embodiment can be seen in FIG. 20, in which the entire top
surface 2000 of a tile 2002 is molded of the first polymer
compound. While the top surface 2000 can be featureless except for
texturing, in this illustrated embodiment an array of features
2004, which can be rounded squares or which can take any other
desired shape, are upstanding from a general top surface 2006. A
bottom surface of this illustrated embodiment can be exactly as it
appears in FIGS. 3, 5, 10, 12 and 13. In this embodiment there are
no through-holes or gates between the upper and lower surfaces of
the tile 2002. This embodiment and the embodiment shown in FIGS.
1-13 can be made using much the same molding apparatus, by swapping
out a cavity-side mold insert adjacent the top surface 108, 2000
and leaving a core side (adjacent the lower surface) alone. This
illustrated embodiment will still exhibit non-slip properties
relative to the substrate on which it is placed, may have better
chemical and wear resistance, and may cost less to produce.
[0077] Considering together the embodiment illustrated by the
combination of FIGS. 3, 5, 10, 12, 13 and 20, raised features 2004
are more likely to receive a disproportionate amount of weight from
a vehicle or other heavy object superimposed on the tile 2002. It
is therefore preferred that some of the support members, such as
members 800 (FIG. 8), receive all or some of the columnar load
placed on any raised feature 2004. In the illustrated embodiment,
each annular support member 800 (see FIG. 8) is in approximate
registration with a respective raised feature 2004 and as such will
militate against shearing between the boundary of the raised
feature 2004 and the surrounding general surface 2006.
[0078] FIGS. 21 and 22 show a fifth embodiment of the invention in
which modifications to the latch and loop structure have been made.
In this embodiment an undercut or trench 2100 is made behind
(laterally inwardly from) the lateral edge 204, but laterally
outwardly from the rib segment 1022, to approximately fifty percent
of the thickness of web 200. The undercut 2100 extends in parallel
to edge 204 for the interior length of the wall segment 1022
between its attachment points (1024, 1026; FIG. 10) with female
loop 208. The undercut 2100 leaves a downwardly depending flange
2102 which, when surface 2104 of outer wall 2106 slides vertically
downward along surface 204, will flex inward (to the left in this
picture) in approximately the direction of arrow 2108. The depth of
the undercut 2100 is chosen to get a sufficient flexure of the
flange 2102 upon snapping the tiles together, and may be more or
less deep than shown depending on the flexural modulus of the
polymer used to mold tile body 104. Flexing flange 2102 permits
latch 206 to more easily snap into loop 208 and places less stress
on loop 208 while joining two adjacent tiles. The inner latch wall
2110 may be made thicker and preferentially has a preferably
flattened, inner ramped surface 2112 which cams against corner 1106
as the right tile 102C is pressed downward to join it with left
tile 102D, until ledge 2120 clears lower edge 2116 of flange 2102.
Ramped surface 2112 preferably extends downwardly and laterally
outwardly from innermost limit 1302 of latch 2118. After the tiles
102C, D are snapped together, there will remain a hatched
interference region 2114 between inner latch wall 2110 and outer
female loop 208, keeping the tiles 102C, 102D biased together or in
compression with each other; the physical position of loop 208 will
actually be displaced rightward from that shown in FIG. 21.
[0079] Preferably a lower edge 2116 of the flange 2102 is slightly
relieved (or upwardly displaced) from the plane of the general
lower surface 306. This permits an easier overdrive of male latch
2118 into female loop 208 and better assures an audible click when
horizontal ledge 2120 snaps beyond lower edge 2116.
[0080] FIGS. 23 through 27 show another embodiment of the
invention. In this embodiment, the bottom view of a tile 2301,
shown in FIG. 23, shows sixteen groups 2300 of support members
2302. The body 2303 may be molded from a first polymer compound and
have an upper surface 2602 (see FIG. 26) and a general lower
surface 2306. One or more upper features 106 (FIG. 2), such as
pads, may be formed or overmolded into the upper surface 2602 with
a second polymer compound. As completed, the upper features or pads
106 on upper surface 2602 (FIG. 26) may look identical to the ones
of embodiments previously described herein. One or more lower
features 2302 (FIG. 23), such as support members or skins, may be
overmolded onto the lower surface 2306 of the body 2303 from the
second polymer compound. As above, the second polymer compound
preferably has a higher coefficient of friction than the first
polymer compound so that the upper features 106 and the lower
features 2302, or skins, act as nonslip surfaces. Alternatively or
additionally, they may be made in a color different from that of
the tile body 2303.
[0081] FIGS. 24 and 25 show the details of the tile lower surface
2306. Specifically, these FIGUREs show a single group 2300 of
support members 2302 before (FIG. 24) and after (FIG. 25) the
second polymer compound is overmolded onto the body 2303 of the
tile 2301. FIG. 24 shows there can be seen a plurality of support
member cores 400 which depend downwardly (in this view, extending
toward the top of the paper) from the general lower surface 2306 of
the substantially horizontal web 200 that makes up most of the tile
body 2303. One or more through-holes 602 connect the upper surface
2602 (see FIG. 26) with the lower surface 2306. Similarly, one or
more vent holes 2402 connect the upper surface 2602 with the lower
surface 2306 of the tile 2301. Preferably, each vent hole 2402 is
in a location that is laterally interior to and within a periphery
of a respective upper feature 106. Each upper feature 106 has a
through-hole 602 and a vent hole 2402 communicating to it and these
are laterally spaced from each other. Preferably the vent hole 2402
for any particular pad 106 should be positioned at a location that
is farthest from the through-hole 602 therefor, while still being
laterally within the periphery of the cavity that will form the pad
or upper feature 106.
[0082] FIG. 26 shows the details of an area on the top of tile
2301, prior to overmolding. Each overmolded pad 106 (see FIG. 7)
may reside in a shallow recess or receptacle 2600 whose surface is
lower than that of the general upper surface 2602. For each recess
2600, there is provided at least one through-hole 602 and at least
one vent hole 2402, each of which communicates the top surface of
the tile web 200 to a lower surface thereof. In the illustrated
embodiment, the through-holes 602 and vent holes 2402 make up a
small fraction (about 5% each) of the bottom of the recesses 2600.
Each of the recesses 2600 form respective lower portions of the
cavities in which upper features or pads 106 will be formed, the
remainder of the surfaces thereof being constituted by the other
mold half. Limiting the size of through-holes 602 and vent holes
2402 enhances the structural integrity of the tile 2301. However,
in alternative embodiments, the size and/or number of the
through-holes 602, and even vent holes 2402, may be increased to
accommodate more highly viscous second-shot polymer compounds.
[0083] The recesses 2600 are each laterally surrounded by a crush
ring 604. See FIG. 26. Each crush ring 604 is finished to be smooth
(in contrast, the general upper surface 2602 of the body 2303 can
be textured) and can be slightly raised relative to the general
upper surface 2602. The crush rings 604 each adjoin the periphery
of a respective upper feature 106 and provide a tight overmold
shutoff that prevents the flashing of the second polymer compound
outside the confines of the crush rings 604. FIG. 25 further shows
that a portion 2310 of at least one upper feature, or pad, 106 (see
FIG. 7) may extend through the vent hole 2402 below the general
lower surface 2306. As shown in FIGS. 23 and 25, the portion 2310
extending through the vent hole 2402 may be discontinuous with or
spaced from the second polymer compound of the lower support member
2302. As described in more detail below, this spacing may be
accomplished by providing a portion of the crush pad 2406 between
the vent hole 2402 and the cores 400.
[0084] The crush pad 2406 is formed into the body 2303 in a manner
similar to the crush ring 604 to be slightly lower than the general
surface 2306 (in this bottom view, is slightly raised relative to
general surface 2306). The crush pad 2406 is formed to be closely
adjacent all of the support member cores 400 and to laterally
surround all of the cores 400, the runners 502 connecting the lower
features 304, the through-holes 602, and the vent holes 2402 (and
therefore portions 2310). The crush pad 406 is finished to have a
smooth surface and is used as a shutoff surface that prevents the
flashing of the second polymer compound during a "second shot" or
overmolding step of fabrication.
[0085] In an arrangement similar to that illustrated and described
previously (see FIG. 19), a second polymer compound gate 1902 is
disposed to be adjacent to the lower surface 2306 and remote from
the upper surface 2602. The gate 1902 communicates with the upper
feature 106 through fill point 504 and a through-hole 602 that
extends from the lower surface 2306 to the upper surface 2602. The
gate 1902 is in direct communication with each lower feature 2302
by a path which does not pass through the body 2303.
[0086] FIG. 25 shows the same area after overmolding. The second
polymer compound now appears on the bottom surfaces and sides of
each of the cores 400 as a lower feature 2302 or skin. While the
second polymer skin could be overmolded separately on each core
400, in the illustrated embodiment, the second polymer within the
support member group 2300 is part of a continuous phase. The second
polymer preferably does not extend to regions outside of, and is
contained by, the crush pads 2406.
[0087] FIG. 27 shows that a plurality of upper features 106 and
lower features 800, 802 can be formed from one gate 1902 (FIG. 19).
It can be seen that the molten second polymer flows from the gate
1902 (see FIG. 19) to the fill point 504 and directly to the lower
surface 2306 to form the lower features 800, 802. This path does
not go through the first-shot tile body 2303. FIG. 27 also shows
that each upper feature 106 is in communication with a respective
vent hole 2402. The second polymer flows from the gate 1902, to the
fill point 504, and through the through-hole 602 to form a
respective upper feature 106. For each feature or pad 106, the
second polymer flows from the through-hole 602 and flows into and
fills a respective mold cavity formed in part by a recess 2600, and
back through the vent hole 2402. In this way, any gas in the
polymer flow-path is displaced, and defects or voids at the
end-of-fill point in the overmolded upper feature 106 caused by
trapped gas can be minimized or prevented. This trapped gas
otherwise can cause burn marks, short shots, and/or poor adhesion
of the upper features 106 to the body 2303.
[0088] The structure shown in FIG. 24 is one possible first-shot
body structure that promotes the displacement of any gas out of the
upper feature cavity. Each core 400 may be interrupted or truncated
to provide lateral separation from the vent hole 2402, which is
preferably placed at a position farthest away from the
through-hole. Where, as here, the upper feature 106 takes on a
roughly square or rectangular shape, the through-hole 602 and the
vent hole 2402 can be disposed in opposite corners of the upper
feature. The positioning of vent hole 2402 preferably should be
such that the molten second-shot polymer flowing from the
through-hole 602 will reach the vent hole 2402 only after reaching
the rest of the cavity defined in part by recess 2600. After
molding (FIG. 25), the separation between core skin 2302 and
portion 2310 is maintained by the crush pad 2406, which seals the
portion 2310 of the upper feature 106 or pad extending through the
vent hole 2402 from the lower features 2302 or skins molded onto
the cores 400. This separation of the top flow (through the
through-hole 602, over the recessed area 2600, and through the vent
hole 2402) and the bottom flow (from the fill point 504, to the
runner 502, to the lower feature 2302 or skin) prevents the top and
bottom flows from interfering with one another in correctly filling
the volumes into which the second polymer is to be overmolded.
[0089] FIG. 28 illustrates a method 2800 of manufacturing a modular
floor tile 2301 according to the invention. At 2802, the first-shot
injection mold is formed, including forming (2804) structures which
will make one or more through-holes 602, and forming (2806) one or
more vent holes 2402. Optionally structures which will form one or
more recesses 2600 can be formed at step 2808, the recesses 2600
then acting as portions of the cavities in which the upper features
or pads 106 will be later molded. At step 2810, structure defining
the crush ring(s) 604 are formed on the upper surface 2602 of the
first-shot body 2303, so as to laterally surround each upper
feature and preferably to be elevated above the general upper
surface. For each such upper feature, at least one through-hole and
at least one vent hole is made, and these preferably are spaced to
be at opposite ends of the upper features to which they
communicate. At step 2812, crush pad(s) 2406 are defined on the
lower surface 2306 of first-shot body 2303, so as to laterally
surround each lower feature to be molded in the second shot, and
also to laterally surround each vent hole 2402.
[0090] At step 2814, the second-shot mold half is created. The
structures formed in this step include a fill point or gate 504,
1902, which is located to be adjacent the lower surface 2306 of the
first-shot body 2303 and remote from the upper surface 2602
thereof. Cavities for the second-shot runners 502 (FIG. 27) are
also formed at this step.
[0091] The first polymer compound is injected into the first-shot
injection mold at step 2820; this will form a first-shot tile body
2303 as seen in FIGS. 24 and 26.
[0092] The second polymer compound is injected into a second-shot
injection mold at step 2822, to overmold upper features 106, and
preferably also lower features 800, 802, onto the respective upper
and lower surfaces of the tile body. The second polymer compound is
introduced (2824) to the mold at a gate 1902 and fill point 504,
for each connected group of upper and lower features. In one
embodiment, there are 16 such gates and fill points on one tile.
The second polymer flows by runners 502 to the through-hole(s) at
step 2824. At step 2826, the second polymer flows in each connected
through-hole 602 from the lower surface to the upper surface,
reaching the cavity(ies) which each define respective upper
feature(s). The upper feature cavity(ies) are filled at step 2828.
At step 2830, the crush ring(s) shut off the second polymer
compound from flashing across the upper surface of the part. The
second polymer compound pushes any gas through vent hole(s) 2402,
minimizing or obviating any defects in the upper feature(s). To
positively assure that this is accomplished, at step 2832 second
polymer compound may flow through each vent hole 2402 to protrude
onto the lower surface 2306. The crush pad 2406 and associated mold
half isolate this second polymer portion 2310 from next-adjacent
lower features 800.
[0093] While the second polymer compound is molding the upper
feature(s) at steps 2824-2832, it can also create lower feature(s)
at steps 2834-2840. At step 2834, second polymer compound flows
from gate 1902 and fill point 504 into and through one or more
runners 502. At step 2836, the runners 502 permit second polymer
compound to reach each of the lower feature(s) 800, 802, where the
cavity(ies) defining them are filled (2838). At step 2840, the
crush pad(s) 2406, in conjunction with the mating second-shot mold
half (not shown), shut off the molten second polymer compound,
preventing the flash of same over the lower surface 2306. The mold
half and crush pad(s) 2406 also isolate second polymer portion 2310
from the second polymer compound flowing in to form feature(s) 800,
802. In this way, there is no hydraulic interference between the
molten polymer compound flowing into and forming the upper
feature(s) and the molten polymer compound flowing into and forming
the lower feature(s), and any air or inert gas will be expelled
from the upper surface features.
[0094] While embodiments of the present invention have been
described in the above detailed description and illustrated in the
appended drawings, the present invention is not limited thereto but
only by the scope and spirit of the appended claims.
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