Note: Descriptions are shown in the official language in which they were submitted.
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SANDING TOOL WITH MOLDED INTERFACE PAD
Background
The present invention relates generally to hand-held, manually-operated,
sanding tools that use a sheet of abrasive material such as sandpaper.
Manually-operated hand sanding tools, such as sanding blocks, are commonly
used with abrasive sheets, such as conventional sandpaper, to hand sand or
finish a work
surface. A commercially available sanding block is the 3MTm Rubber Sanding
Block
available from 3M Company, St. Paul, MN. Hand sanding tools may include a foam
interface
pad that is adhesively bonded to the working face of the sanding tool. Such
interface pads,
however, suffer from one or more drawbacks or shortcomings. It would be
desirable to
provide a hand-held, manually-operated, sanding tool that includes an
interface pad that
overcomes the drawbacks and shortcomings of sanding tools having adhesively
bonded foam
interface pads.
Summary
An embodiment of the present invention provides a hand-held, manually-
operated, sanding tool for use with a replaceable sheet-like abrasive material
that includes a
base member formed of a first material, a molded interface pad formed of a
second injection
moldable material provided on the base member, thereby defining a working face
against
which the sheet-like abrasive material is arranged, and a retaining mechanism
arranged to
maintain the sheet-like abrasive material in operative relation with the
interface pad.
According to an aspect, there is provided a hand-held, manually-operated,
sanding tool for use with a replaceable sheet-like abrasive material,
comprising: (a) a base
member defining opposing first and second surfaces and a plurality of slots,
the slots
extending from, and open at, the first surface and closed relative to the
second surface; (b) a
molded interface pad provided on the base member to define a working face
against which the
sheet-like abrasive material is arranged and a second face opposite the
working face, the
second face forming a plurality of extensions, respective ones of which are
molded within
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respective ones of the slots; and (c) a retaining mechanism arranged to
maintain the sheet-like
abrasive material in operative relation with the interface pad; wherein the
base member is
formed of a first material and the molded interface pad is formed of a second,
injection
moldable, material.
There is also provided a method of making such a sanding tool, comprising the
steps of: (a) providing a sanding tool including a base member formed of a
first material and
having a bottom surface defining a plurality of slots; and (b) forming an
interface pad on the
base member by injection molding an elastomeric material different from the
first material
over the bottom surface, including injection molding extensions of the
interface pad into
corresponding slots of the base member.
In one aspect, the first material has a Shore hardness that is greater than
the
Shore hardness of the second material (i.e. the interface pad is softer than
the base member).
In a more specific aspect, the first material has a Shore D hardness of
greater than about 30,
and the second material has a Shore A hardness of less than about 95.
In one embodiment, the interface pad is a polymeric material. In a more
specific embodiment, the interface pad is an elastomeric material. In another
aspect, the
interface pad includes a textured working surface opposite the base member. In
more specific
aspects, the interface pad working face includes a macroscopically three-
dimensional surface
topography. The surface topography may comprise a random three-dimensional
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surface topography or it may comprise a regular non-random pattern defined by
raised
regions and recessed regions.
In another aspect, the base member contains slots and the interface pad
includes
extensions extending into the slots, thereby to form a secure connection
between the base
member and the interface pad.
In yet another aspect, the present invention provides a method of making a
hand-
held, manually-operated, sanding tool for use with a replaceable sheet-like
abrasive
material comprising a base member formed of a first material, a molded
interface pad
formed of a second injection moldable material provided on the base member,
thereby
defining a working face against which the sheet-like abrasive material is
arranged, and a
retaining mechanism arranged to maintain the sheet-like abrasive material in
operative
relation with the interface pad, wherein the method comprises the steps of
providing a
sanding tool including a base member having a working face, and forming an
interface pad
on the base member by injection molding an elastomeric material over the
working face.
Advantages of certain embodiments of the invention include improved sanding
capability, improved product design flexibility (that is, the product design
can be more
easily tailored or adapted to a specific end-use application), easier and less
expensive
manufacturing, and a sanding tool that is easier and more comfortable to use.
Brief Description of the Drawings
The present invention will be further described with reference to the
accompanying
drawings, in which:
FIG. 1 is a perspective view of a hand-held, manually-operated, sanding tool
having a molded interface pad according to the invention;
FIG. 2 is a side view of the sanding tool of Fig. 1;
FIG. 3 is a detailed view of the base member and the interface pad; and
FIGS. 4a and 4b are plan views showing alternate three-dimensional surface
topographies for the interface pad.
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Detailed Description
Referring now to the drawings, wherein like reference numerals refer to like
or
corresponding puts throughout the several views, FIGS 1 and 2, show a hand-
held,
manually-operated sanding tool or sanding block 2 for use with a flexible,
replaceable,
sheet-like abrasive material 40. The term "manually-operated" refers to the
fact that the
tool 2 is not a power tool. That is, all of the power for the tool is provided
by the user and
the tool itself does not include a motor. The term "sheet-like abrasive
material" refers to
thin, flexible, typically square or rectangular sheets of abrasive material
having discrete
ends that can be attached to a sanding block. Such sheet-like abrasive
materials include,
1 0 for example, conventional sandpaper, flexible sanding scrims, non-woven
abrasive
materials such as ScotchbriteTM available from 3M Company, St. Paul, MN, and
thin
flexible abrasive sheet materials such as those described in U.S. Patent No.
6,613,113
(Minick et al.). The tool may also find use with non-abrasive sheet-like
materials
such as dust removing tack cloth materials. The term, however, does not
include
endless belts of abrasive material commonly used on power sanding tools, or
die
cut sheets that are sold pre-cut to match the size and shape of a particular
sanding
tool as is commonly done for power detail sanding tools.
The sanding tool 2 shown and described herein is described more fully in U. S.
Patent No. 7,182,681. For the present invention, however, the
sanding tool 2 generally is not particularly significant as long as it is
capable of including
an interface pad and includes certain basic features such as the ability to
receive and retain
a sheet-like abrasive material. Thus, it will be understood that the sanding
tool 2 shown
and described below is intended to represent any sanding tool capable of
having a molded
interface pad.
The sanding tool 2 includes a base member 4 and a pair of clamping mechanisms
6, 8 connected with opposed ends of the base member 4. Although the sanding
tool 2 is
shown with clamping mechanisms 6, 8 at both ends, it will be recognized that
one or both
of the clamping mechanisms 6, 8 may be replaced with a conventional mechanism
for
securing the abrasive sheet-like material 40 to the tool. It will also be
recognized that
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although the base member 4 is shown as being rectangular, it may also be
square or other
shapes that lend themselves for use with conventional abrasive sheets.
The base member 4 has first 10 and second 12 opposed ends and a generally
planar
bottom surface 14. Each end 10, 12 of the base member 4 has an inclined or
angled
contact surface 16, 18, respectively, opposite the bottom surface 14. In this
manner, the
contact surfaces 16, 18 and bottom surface 14 form an acute angle relative to
the
associated adjacent end 10, 12, respectively.
Each clamping mechanism 6, 8 is pivotally connected with opposite ends 10, 12
of
the base member 4 adjacent the contact surface 16, 18, respectively, thereby
defining a jaw
into which the ends 40a, 40b of a sheet-like abrasive material 40 may be
inserted. Each
clamping mechanism 6, 8 is movable between a closed position shown in FIG. 1,
and an
open position shown in FIG. 2. In the closed position, the clamping mechanisms
6, 8 are
fully actuated toward the associated contact surfaces 16, 18, respectively,
and, when no
abrasive material is present, are arranged adjacent to the contact surfaces
16, 18,
respectively. In the open position, the clamping mechanisms 6, 8 are spaced
from the
associated contact surfaces 16, 18, thereby defining gaps 20,21, respectively,
between the
base member 4 contact surfaces 16,18 and the clamping mechanisms 6, 8.
Each clamping mechanism 6, 8 includes a flexible tensioning member 22, 24
arranged to face the associated contact surface 16, 18. Arranged in this
manner, as the
clamping mechanisms 6, 8 are lowered toward the base member 4 to secure the
abrasive
material 40 to the tool 2, the terminal edges of the tensioning members 22, 24
slidably
engage the contact surfaces 16, 18. Thus, when an end 40a, 40b of the abrasive
sheet 40 is
inserted in the gap 20, 21 between the base member 4 and a clamping mechanism
6, 8, and
the clamping mechanism is moved from its open position to the closed position,
the edge
of the tensioning members 22, 24 will frictionally engage the end 40a, 40b of
the sheet of
abrasive material 40.
As the clamping mechanisms 6, 8 are further urged toward the contact surfaces
16,
18, the tensioning members 22, 24 grip the respective ends of the abrasive
sheet 40a, 40b
and move it upwardly along the inclined contact surfaces 16, 18 away from the
associated
end 10, 12, thereby drawing the sheet of abrasive material farther into the
gap 20, 21. In
addition, as the clamping mechanisms 6, '8 are urged against the contact
surfaces 16, 18,
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the tensioning members 22, 24 bow or flex such that the bowed surface of the
tensioning
members 22, 24 will engage the contact surfaces 16, 18, thereby increasing the
overall
contact surface area between the tensioning members 22, 24 and the sheet of
abrasive
material 40. In this manner, slack in the abrasive sheet 40 is taken up,
thereby tightening
the fit of the abrasive sheet 40 against the bottom 14 of the base member 4.
In the illustrated embodiment, the tensioning members 22, 24 are thin flexible
strips of metal, such as a leaf spring, that generally return to their
original positions when
the applied force is released. Other materials such as a stiff resilient
rubber or synthetic
plastic material may also be used. To distribute the force applied by the
tensioning
members 22, 24 to the ends abrasive sheet 40a, 40b evenly (both during the
installation of
the abrasive sheet 40 onto the tool and while the abrasive sheet is being held
onto the tool),
the tensioning members 22, 24 extend continuously across the entire width of
the clamping
mechanisms 6, 8. By distributing the force in this manner, the tensioning
members 22, 24
have a reduced tendency to tear or otherwise damage the abrasive sheet
material 40.
To further reduce the likelihood that the ends of the tensioning members 22,
24
will dig into the abrasive sheet 40, and thereby possibly damage the abrasive
sheet, in an
alternative embodiment, the tensioning members 22, 24 may be curved or bowed
inwardly
such that the tensioning members 22, 24 have curved surfaces that face the
contact
surfaces 16, 18, and engage the contact surfaces when the clamping mechanisms
22, 24 are
closed.
In accordance with a characterizing aspect of the sanding tool 2, a molded
interface
pad 26 is provided on the bottom surface of the base member 4. The interface
pad 26
defines the surface against which the sheet-like abrasive material 40 is
secured. By
providing a molded interface pad 26, the base member 4 and interface pad 26
form an
integrally molded body including an upper portion defined by the base member
4, and a
lower portion defined by the interface pad 26. The base member 4 is typically
formed of a
first polymeric material, and the interface pad 26 is typically formed of a
second polymeric
material. The second polymeric material used to form the interface pad 26 is
typically
softer than the material used to form the base member 4. The molded interface
pad 26
may be formed of any moldable material but is typically a soft, resiliently-
flexible,.
= elastomeric, injection moldable material. Suitable injection moldable
materials include
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natural and synthetic rubbers including latex and butyl rubber, thermoplastic
elastomers
such as polyurethane elastomers, thermoplastic vulcanizate, and thermoplastic
rubber.
Suitable materials for the interface pad 26 typically have a Shore A hardness
of less than
about 95 and, more typically, less than about 70. A suitable material for the
molded
interface pad 26 is available from Advanced Elastomer Systems, an affiliate of
ExxonMobil Chemical, under the trade designation Santoprene.
Generally, the base member 4 is formed of a material having a Shore hardness
that
is greater than the Shore hardness of the material used to form the interface
pad. Suitable
materials for the base member include hard synthetic plastic materials,
typically thermo set
or thermoplastic materials such as ABS (acrylonitrile butadiene styrene),
polypropylene,
polyethylene, and blends containing such materials. Suitable materials for the
base
member 4 typically have a Shore D hardness of greater than about 30. A
suitable material
for the base member 4 is available from GE Plastics under the trade
designation Cycolac
and Cycoloy (an ABS polycarbonate blend).
FIG. 3 is a detailed view showing the interconnection between the base member
4
and interface pad 26. In the illustrated embodiment, the base member 4
contains recesses
or slots 28 and the interface pad 26 includes extensions 30 that extend into
the slots 28. In
this manner, a mechanical connection, which resists dissociation, is formed
between the
base member 4 and the interface pad 26. To further enhance the interconnection
between
the interface pad 26 and the base member 4, and thereby prevent the interface
pad 26 from
separating from the base member 4, the slots 28 include optional flared end
regions 28a,
and the extensions 30 include flared terminal portions 30a that extend into
the flared end
regions 28a of the slots 28. Other structural features for forming the
mechanical
attachment between the base member 4 and the interface pad 26 are contemplated
in
connection with the present invention. The mechanical connection may be
formed, for
example, by a single protrusion, which may have a variety of shapes, that
mates with a
cooperating recess. The protrusion and recess may be formed in either the base
member 4
or the interface pad 26.
Alternatively, base member 4 and the interface pad 26 may be formed via a
chemical bond. When attached by a chemical bond, the interface between the
base
member 4 and the interface pad 26 may be generally planar (i.e. the base
member 4 and the
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interface pad 26 each include generally planar surfaces that are attached to
each other) or
the interface may include structural features such as those described above to
further
enhance the interconnection between the base member and the interface pad 26.
The
chemical bond is formed by selecting compatible materials that form a strong
chemical
bond.
As shown in FIG. 4, the exposed working face of the interface pad 26 (i.e. the
surface of the interface pad 26 opposite the base member 4 against which the
abrasive
sheet 40 is arranged) may include a textured surface 32 having a three-
dimensional surface
topography. The three-dimensional surface topography is typically macroscopic
meaning
the height differential between the raised regions and the recessed regions is
greater than
about 1 millimeter. As shown in FIG. 4a, the textured surface 32 may be a
random pattern
of raised regions 34 separated by recessed regions 36 or, as shown in FIG. 4b,
the textured
surface may be a regular repeating pattern of raised regions 34 and recessed
regions 36.
Other surface geometries are contemplated in connection the present invention.
For
example, the size and shape of the raised and recessed regions may be varied
or tailored
depending on the type of abrasive sheet used and/or depending on the specific
end use
application for the tool.
The combination of the base member 4 and the interface pad 26 may be formed,
for
example, using known multi-material injection molding techniques including co-
injection
molding, overmolding, and multi-shot molding. For example, the base member 4
may be
formed by injection molding a suitable material, such as ABS, into a mold to
form the base
member 4, and the interface pad 26 may be formed by injection molding a
suitable
material, such as Santoprene, to form the interface pad 26. Alternatively, the
base member
4 may be formed by casting or other known techniques.
Injection molding the interface pad 26 offers a number of advantages over the
use
of conventional interface pads, which are foam pads that are adhesively bonded
to the
sanding tool 2. First, because the molded interface pad is injection molded,
the additional
steps of die cutting a foam sheet to the appropriate size and adhesively
bonding the foam
pad to the bottom of the base member 4 are eliminated. This simplifies the
assembly
process and also eliminates the raw material costs associated with the foam
pad and
adhesive. Injection molding the interface pad 26 also reduces the likelihood
of failures
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between the interface pad and the base member 4 (i.e. injection molding
provides a
chemical and/or mechanical bond between the interface pad 26 and base member 4
that is
unlikely to allow the interface pad 26 to inadvertently separate from the base
member 4).
The injection molded interface pad 26 may also include a variety of textures
and/or
patterns, it may be formed of any number of suitable moldable polymer
materials
depending on the desired durability and conformability properties, and it may
be formed in
a variety of colors or thicknesses, thereby greatly increasing the design
options and design
flexibility of the tool, and further allowing the tool design to be easily
tailored for specific
end uses.
The sanding tool 2 also includes a handle 46. In the illustrated embodiment,
the
handle 46 includes a neck portion 46a that extends upwardly from a central
region of the
base member 4, and includes an enlarged head portion 46b located at the end of
the neck
46a that defines a knob 48 that can be readily grasped by a user to maneuver
and control
the movement of the tool 2. To provide the user with a more comfortable grip,
the knob
48 portion of the handle 46 preferably comprises an interior region 48a formed
of a
relatively hard first material and a peripheral region 48b formed of a
relatively soft rubber-
like second material that is easier to grip and thereby provides the user with
improved
handling. The first relatively hard material, may be, for example, a hard
synthetic plastic,
and the relatively soft second material may be, for example, a thermoplastic
elastomer,
rubber, rubber-like materials or foam.
The tool 2, including the base member 4, clamping mechanisms 6,8 and handle
46,
may be formed of any suitable material including, for example, wood, metal,
synthetic
plastic, or a stiff rubber.
Those of ordinary skill in the art may appreciate that various changes and
modifications may be made to the invention described above without deviating
from the
inventive concept. For example, it will be recognized that the size of the
tool may be
adapted so it can be used with the various standard sizes of commercially
available
abrasive sheets. Thus, the scope of the present invention should not be
limited to the
structures described in this application, but only by the structures described
by the
language of the claims and the equivalents of those structures.
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