U.S. patent application number 17/291379 was filed with the patent office on 2022-01-06 for releasable tool attachment means for power trowels.
The applicant listed for this patent is Husqvarna AB. Invention is credited to Tristan Nijs, Martin Renneson, Tchavdar Tchakarov.
Application Number | 20220001515 17/291379 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-06 |
United States Patent
Application |
20220001515 |
Kind Code |
A1 |
Tchakarov; Tchavdar ; et
al. |
January 6, 2022 |
RELEASABLE TOOL ATTACHMENT MEANS FOR POWER TROWELS
Abstract
A tool driver for a power trowel, the tool driver comprising a
combination of a magnetic fastening arrangement and a friction
based fastening arrangement for releasably holding an abrasive tool
to the tool driver, wherein the magnetic fastening arrangement is
configured symmetrically around a rotational center of the tool
driver, wherein the friction based fastening arrangement is adapted
to provide increased shear strength during abrasive operation of
the tool, and wherein the magnetic fastening arrangement is adapted
to provide increased pull strength during lifting of the tool
driver.
Inventors: |
Tchakarov; Tchavdar;
(Monroe, MI) ; Renneson; Martin; (Brussels,
BE) ; Nijs; Tristan; (Hoves, BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Husqvarna AB |
Huskvarna |
|
SE |
|
|
Appl. No.: |
17/291379 |
Filed: |
June 27, 2019 |
PCT Filed: |
June 27, 2019 |
PCT NO: |
PCT/EP2019/067196 |
371 Date: |
May 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16194879 |
Nov 19, 2018 |
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17291379 |
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International
Class: |
B24D 9/08 20060101
B24D009/08; B24B 7/18 20060101 B24B007/18; B24B 41/047 20060101
B24B041/047; E04F 21/24 20060101 E04F021/24 |
Claims
1. A tool driver for a power trowel, the tool driver comprising a
combination of a magnetic fastening arrangement and a friction
based fastening arrangement for releasably holding an abrasive tool
to the tool driver, wherein the magnetic fastening arrangement is
configured symmetrically around a rotational center of the tool
driver, wherein the friction based fastening arrangement is adapted
to provide increased shear strength during abrasive operation of
the tool, and wherein the magnetic fastening arrangement is adapted
to provide increased pull strength during lifting of the tool
driver.
2. The tool driver according to claim 1, wherein the friction based
fastening arrangement comprises a tool driver surface with
protrusions configured to engage with a yielding surface material
on the abrasive tool to provide the increased shear strength.
3. The tool driver according to claim 1, wherein the friction based
fastening arrangement comprises a material with hooks for holding
respective loops on the abrasive tool or wherein the friction based
fastening arrangement comprises a material with loops for holding
respective hooks on the abrasive tool.
4. The tool driver according to claim 2, wherein the yielding
surface material or the material with loops is a felt-like cloth, a
fibrous material, a foam, rubber, and/or a non-synthetic
material.
5. The tool driver according to claim 1, wherein the magnetic
fastening arrangement comprises a plurality of magnets arranged
symmetrically around a rotational center of the tool driver.
6. The tool driver according to claim 1, wherein the magnetic
fastening arrangement comprises a metal element responsive to a
magnetic force from the abrasive tool.
7. The tool driver according to claim 1, wherein the tool driver
comprises centering means for centering the abrasive tool with
respect to the rotational center of the tool driver.
8. The tool driver according to claim 1, wherein the tool driver
has a diameter between 7 and 25 inches.
9. The tool driver according to claim 1, wherein the tool driver is
arranged to interface with a secondary tool driver.
10. The tool driver according to claim 9, wherein the magnetic
fastening arrangement comprises magnets extending through the tool
driver to engage with the abrasive tool on one side of the tool
driver and to engage with the secondary tool driver on the other
side of the tool driver.
11. The tool driver according to claim 9, comprising protruding
elements having shapes matched to corresponding recesses formed in
the secondary tool driver.
12. The tool driver according to claim 9, comprising one or more
notches formed in the rim of the tool driver, to allow a better
grip by a hand removing the tool driver from the secondary tool
driver.
13. An abrasive tool for a power trowel, the abrasive tool
comprising a combination of a magnetic fastening arrangement and a
friction based fastening arrangement for being releasably held by a
tool driver on a first side of the abrasive tool, wherein the
magnetic fastening arrangement is configured symmetrically around a
rotational center of the tool, wherein the friction based fastening
arrangement is adapted to provide increased shear strength during
abrasive operation of the tool, and wherein the magnetic fastening
arrangement is adapted to provide increased pull strength during
lifting of the tool.
14. The abrasive tool according to claim 13, wherein the friction
based fastening arrangement comprises a yielding surface material
configured to engage with protrusions on arranged on the tool
driver surface to provide the increased shear strength.
15. The abrasive tool according to claim 13, wherein the friction
based fastening arrangement comprises a surface material with hooks
for holding respective loops on the tool driver or wherein the
friction based fastening arrangement comprises a surface material
with loops for holding respective hooks on the tool driver.
16-20. (canceled)
21. The abrasive tool according to claim 13, comprising an abrasive
component or compound arranged on a second side of the abrasive
tool opposite to the first side.
22. The abrasive tool according to claim 21, wherein the abrasive
component is supported at least partly by a flexible supporting
element.
23. The abrasive tool according to claim 13, wherein the magnetic
fastening arrangement comprises a metal ring having a diameter
smaller than a diameter of the tool.
24. The abrasive tool according to claim 13, comprising; a fibrous
pad including an upper surface, a floor-facing lower surface and a
peripheral surface; a reinforcement layer attached to the bottom
surface of the pad, the reinforcement layer including an internal
edge defining a hole therethrough; abrasive disks attached to a
floor-facing surface of the reinforcement layer; a central area of
the pad being exposed through the hole of the reinforcement layer
such that a linear dimension of the central area within the hole is
greater than a linear dimension of one side of the reinforcement
layer between the hole and a periphery thereof; and where a
magnetic ring arranged on the upper surface constitutes the
magnetic fastening arrangement, wherein the magnetic ring has an
outer diameter smaller than an outer diameter of the reinforcement
layer.
25. (canceled)
26. (canceled)
27. A method of attaching an abrasive tool to a tool driver for a
power trowel, comprising; configuring a combination of a magnetic
fastening arrangement and a friction based fastening arrangement
for releasably holding an abrasive tool to the tool driver, wherein
the magnetic fastening arrangement is configured symmetrically
around a rotational center of the tool driver; and releasably
holding the tool by the tool driver.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to power trowels and to
machines in general for levelling and polishing concrete surfaces
such as floors and the like. There are disclosed means for
attaching abrasive tools to one or more power trowel tool drivers,
in particular flexible abrasive tools. There are also disclosed
adapters for attaching abrasive tools to existing tool driver
geometries.
BACKGROUND
[0002] Trowel polishing is a new trend in the construction
industry. Trowel polishing comprises use of abrasive tools, e.g.,
diamond tools, for smoothing and polishing large concrete surfaces
such as flooring and the like. Similar equipment can also be used
for polishing stone and marble surfaces, although concrete is the
most common.
[0003] A power trowel, also known as a "power float", is a piece of
construction equipment used by construction companies and
contractors to apply a smooth finish to concrete slabs. Power
trowels differ in the way they are controlled;
[0004] Walk-behind power trowels are used by an operator walking
behind the machine.
[0005] Ride-on power trowels are used by an operator sitting on a
seat upon the machinery, controlling the power trowel with control
means.
[0006] A hand tool for the same task is often referred to as a
concrete float. A float is used after the surface has been made
level using a screed. In addition to removing surface
imperfections, floating will compact the concrete as preparation
for further processing steps.
[0007] Power trowels use abrasive tools held by tool drivers for
abrading surfaces. The tool driver is rotatably attached to a motor
which powers the tool driver, and the tool is then attached to the
tool driver for abrasive operation.
[0008] The abrasive tools used by the power trowel are replaced
regularly by, e.g., tools having finer and finer grit size, and
also as they are worn out. Thus, the tools are preferably arranged
releasably held by the tool driver of the power trowel to
facilitate replacement. The tools need to be held firmly enough
such that they are not accidentally released during abrasive
operation due to shear forces acting on the tool drivers and
abrasive tools, but not too firmly since this would make tool
replacement inconvenient.
[0009] There is a need for abrasive tools and corresponding tool
drivers which facilitate tool replacement while at the same time
providing sufficient support for an efficient abrading
operation.
SUMMARY
[0010] It is an object of the present disclosure to provide
abrasive tools and tool drivers which facilitate tool replacement
and at the same time provide for efficient and robust abrading
operation without accidental tool release.
[0011] This object is at least in part obtained by a tool driver
for a grinder, power trowel, or other planetary grinding system.
The tool driver comprises a combination of a magnetic fastening
arrangement and a friction based fastening arrangement for
releasably holding an abrasive tool to the tool driver. The
magnetic fastening arrangement is configured symmetrically around a
rotational center of the tool driver. The friction based fastening
arrangement is adapted to provide increased shear strength during
abrasive operation of the tool, while the magnetic fastening
arrangement is adapted to provide increased pull strength during
lifting of the tool driver.
[0012] Thus, advantageously, both pull strength and shear strength
are provided by the combination of fastening arrangements, while
still allowing for convenient tool replacement.
[0013] The disclosed techniques are particularly suitable for use
with non-rigid tools, i.e., tools comprising a flexible supporting
element for holding an abrasive compound, such as fibrous pads and
the like.
[0014] According to some aspects, the friction based fastening
arrangement comprises a tool driver surface with protrusions
configured to engage with a yielding surface material on the
abrasive tool to provide the increased shear strength.
[0015] The protrusions may, e.g., be pins molded in or otherwise
attached to the surface of the tool driver, thus providing a
cost-efficient yet robust friction based fastening arrangement that
provides increased friction when engaging any type of yielding
surface material, such as a fibrous material or the like. The pins
do not provide any significant pull strength but are complemented
by the magnetic fastening arrangement.
[0016] According to some other aspects, the friction based
fastening arrangement comprises a material with hooks for holding
respective loops on the abrasive tool or the friction based
fastening arrangement comprises a material with loops for holding
respective hooks on the abrasive tool.
[0017] Consequently, a hook and loop based fastening arrangement
can also be used to provide increased friction. The hook side and
the loop side can be arranged on any of the tool driver or the
tool, allowing for flexibility in manufacturing, which is an
advantage.
[0018] According to aspects, the magnetic fastening arrangement
comprises a plurality of magnets arranged symmetrically around a
rotational center of the tool driver.
[0019] Consequently, the tool can be rotated relative to the tool
driver while maintaining pull strength. This simplifies tool
replacement in that the tool need not be attached at any particular
angle with respect to the tool driver.
[0020] According to other aspects, the magnetic fastening
arrangement comprises a metal element responsive to a magnetic
force from the abrasive tool.
[0021] The magnetic fastening arrangement can be implemented with
any combination of metal elements and magnets, which is an
advantage. The metal element can, e.g., be a ring of metal having a
diameter smaller than a diameter of the tool driver. This saves
cost since a smaller ring is used.
[0022] According to aspects, the tool driver comprises centering
means for centering the abrasive tool with respect to the
rotational center of the tool driver.
[0023] The centering means further simplifies tool replacement,
since no trial and error is required during tool alignment, which
is an advantage.
[0024] According to aspects, the tool driver is furthermore
arranged to interface with a secondary tool driver.
[0025] This way the tool driver can function as an adapter to
interface new tools with existing construction equipment, which is
an advantage.
[0026] According to aspects, the magnetic fastening arrangement
comprises magnets extending through the tool driver to engage with
the abrasive tool on one side of the tool driver and to engage with
the secondary tool driver on the other side of the tool driver.
[0027] The magnets thus have dual functions. On one side they act
to provide increased pull strength at the bond between tool driver
and tool, and at the other side they act to releasably attach the
tool driver to the secondary tool driver.
[0028] According to other aspects, the magnetic fastening
arrangement comprises magnets on both sides of the tool driver, to
engage with the abrasive tool on one side and to engage with the
secondary tool driver on the other side of the tool driver.
[0029] According to aspects, the tool driver comprises protruding
elements having shapes matched to corresponding recesses formed in
the secondary tool driver. This way the tool driver interfaces with
the secondary tool driver to provide a robust grinding operation.
The protruding elements having shapes matched to corresponding
recesses formed in the secondary tool driver can be adapted to
different secondary tool drivers, thus providing an adaptation
function with respect to a given secondary tool driver.
[0030] The object is also obtained by an abrasive tool for a
grinder, power trowel, or other planetary grinding system. The
abrasive tool comprises a combination of a magnetic fastening
arrangement and a friction based fastening arrangement for being
releasably held by a tool driver. The magnetic fastening
arrangement is configured symmetrically around a rotational center
of the tool. The friction based fastening arrangement is adapted to
provide increased shear strength during abrasive operation of the
tool, and wherein the magnetic fastening arrangement is adapted to
provide increased pull strength during lifting of the tool.
[0031] The friction based fastening arrangement may optionally be
based on protruding elements such as pins or a hook and loop based
system.
[0032] The abrasive tool is configured for operation together with
the tool driver and is associated with the same advantages as the
tool driver.
[0033] A loop side on the abrasive tool may according to some
aspects be implemented by a fibrous material, such as a felt-like
cloth or similar fibrous material, which is a cost-effective way of
producing the tool. This fibrous material is, according to aspects,
a yielding and flexible supporting element for holding the abrasive
compound. It is noted that this type of felt-like cloth or fibrous
material is different from the known Velcro loop-side that is a
synthetic material comprising a special type of loops.
[0034] The disclosed tools are flexible and/or resilient, i.e.,
compressible to some extent, and of sufficient strength. The
fibrous tools made from felt, thick fabrics, and the like are
possible to wash in water, and also cost effective.
[0035] There are also disclosed herein construction equipment,
grinders, power trowels, and methods associated with the
above-mentioned advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The present disclosure will now be described in more detail
with reference to the appended drawings, where
[0037] FIGS. 1A, 1B and 2 schematically illustrate power
trowels;
[0038] FIG. 3 shows an example tool configuration for a power
trowel;
[0039] FIGS. 4A and 4B schematically illustrate a tool driver for a
power trowel;
[0040] FIGS. 5A and 5B schematically illustrate a tool for a power
trowel tool driver;
[0041] FIG. 6 illustrates a combination of tool and tool driver for
power trowels;
[0042] FIGS. 7A, 7B, 8A, 8B schematically illustrate centering
means;
[0043] FIG. 9 schematically illustrates a tool driver for a power
trowel;
[0044] FIG. 10 schematically illustrates a tool for a tool
driver;
[0045] FIG. 11 shows a collection of example magnet shapes;
[0046] FIG. 12 schematically illustrates a tool driver for a power
trowel;
[0047] FIG. 13 schematically illustrates a tool for a power trowel
tool driver;
[0048] FIG. 14 is a flow chart illustrating methods;
[0049] FIGS. 15A and 15B schematically illustrate a tool for a
power trowel; and
[0050] FIGS. 16A, 16B, 17A-C, 18, and 19A-B schematically
illustrate tool drivers.
DETAILED DESCRIPTION
[0051] Aspects of the present disclosure will now be described more
fully hereinafter with reference to the accompanying drawings. The
different devices and methods disclosed herein can, however, be
realized in many different forms and should not be construed as
being limited to the aspects set forth herein. Like numbers in the
drawings refer to like elements throughout.
[0052] The terminology used herein is for describing aspects of the
disclosure only and is not intended to limit the invention. As used
herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise.
[0053] Herein, a rotational center is a point on an object which
stays fixed as the object is rotated. It is appreciated that
objects which are not designed to rotate during operation still
have rotational centers. For instance, the rotational center of any
disc-shaped object coincides with the center of the disc. The
rotational center of a square object also coincides with the center
of the square object.
[0054] FIGS. 1A, 1B and 2 schematically illustrate power trowels
100, 200 for abrading, levelling and/or polishing surfaces 140,
such as concrete surfaces. The power trowels 100 are walk-behind
power trowels while the power trowel 200 is a ride-on power
trowel.
[0055] A walk-behind power trowel 100 comprises a handle 110 which
the operator uses to guide the trowel. There is a power source 120,
a combustion engine or electrical motor, which powers the trowel
130.
[0056] The ride-on power trowel 200 has a seat with control means
210 where an operator sits and controls the power trowel 200. There
is again a power source 220 which powers the trowel 230.
[0057] Power trowels are generally known and will not be discussed
in more detail here.
[0058] The abrasive tools disclosed herein comprise an abrasive
component or compound arranged on a side of the abrasive tool
opposite to the side which attaches to the tool driver. Thus, an
abrasive operation is performed when the tool is rotated or
otherwise brought in non-stationary contact with a material to be
abraded.
[0059] The abrasive component may be realized in many different
ways; for instance, abrasive coins may be bonded to a ring, such as
a plastic ring, which is glued to the tool. An abrasive compound
can be sprayed onto the tool and bonded thereon by a resin. The pad
itself may also be impregnated by a compound comprising, e.g.,
diamond particles or the like.
[0060] Herein, a tool driver may also be referred to as a tool
holder. It is appreciated that a tool driver need not necessarily
be arranged to rotate about its own center. Rather, a tool driver
may be fixedly attached to an arm which is rotating around some
other center of rotation.
[0061] Herein, a tool driver can be directly attached to the
grinding machine, as illustrated in FIGS. 7A and 7B, or it can be
an adapter used to interface between a given abrasive tool and a
secondary tool driver attached to the grinding machine, as
illustrated in FIGS. 16A and 16B.
[0062] The disclosed techniques can be used for abrasive operation
by a wide variety of different tools and construction equipment,
such as single disc grinders, passive planetary systems, and active
planetary systems. The disclosed tools and tool drivers are
especially suited or use with power trowels but can also be used
with other surfacing machines such as floor cleaning machines and
floor polishing machines.
[0063] FIG. 3 shows an example tool configuration for a power
trowel. A power trowel may comprise one or more such tool
configurations, e.g., 1, 2, or even 4. The trowels 130, 230
comprise tool drivers 300 to which abrasive tools can be releasably
held. Power trowels commonly comprise between 8-12 abrasive tools.
The abrasive tools are often disc-shaped with a diameter of 14''.
However, tool diameters from 7-25 inches may be used with the
disclosed techniques.
[0064] Known tool drivers comprise hook-and-loop systems for
releasably holding the abrasive tool.
[0065] Hook-and-loop fasteners, hook-and-pile fasteners or touch
fasteners (often referred to by the genericized trademark Velcro),
consist of two components: typically, two fabric strips or,
alternatively, round "dots" or squares which are attached (glued,
riveted, sewn or otherwise adhered) to the opposing surfaces to be
fastened. The first component features tiny hooks, the second
features smaller loops. When the two are pressed together the hooks
catch in the loops and the two pieces fasten or bind temporarily.
When separated, by pulling or peeling the two surfaces apart, the
strips make a distinctive "ripping" sound.
[0066] Herein, a friction based fastening arrangement is an
arrangement which provides increased friction between two surfaces
in order to better resist a shear force acting on the surfaces.
Examples of friction based fastening arrangements include
arrangements where one surface comprises protrusions or pins 1605
and the other side is configured with a yielding material such as
fibrous material which the protrusions may puncture, enter or be
received by in some way. When the pins or protrusions extend into
the yielding material, increased friction is obtained. Thus, the
feature of having protrusions configured to engage with a yielding
surface material is to be interpreted broadly. One example is
molded pins extending from one surface to puncture or otherwise
enter another surface such as a fibrous material surface or a
rubber surface.
[0067] It is appreciated that the tool drivers illustrated in FIGS.
4A, 4B, 7A and 7B can be used with any type of friction-based
fastening system, including hook-and-loop based system and
protrusion based systems.
[0068] It is appreciated that the tool drivers illustrated in FIGS.
16A and 16B can be used with any type of friction-based fastening
system, including hook-and-loop based system and protrusion based
systems.
[0069] Another example of a friction based fastening arrangement is
the hook and loop based fastening arrangement discussed above;
Herein, a hook and loop based fastening arrangement is any
arrangement which uses the hook and loop principle to releasably
hold one element to another element. It is appreciated that hook
and loop based fastening arrangements comprise arrangements where
hooks are arranged on one element and loops are arranged on the
other element, regardless of which element is which. Hook and loop
based fastening arrangements also comprise configurations where
combinations of hooks and loops are arranged on both elements.
[0070] Herein, hook and loop based as well as friction based
fastening arrangements also comprise arrangements where the loop
side or yielding surface material side comprises a fibrous
material, such as a cloth or felt-like material. It is appreciated
that most fibrous materials are yielding and therefore configured
to receive pins or protrusions and attach to some extent to a hook
side of a hook and loop based fastening arrangement, since the
hooks catch on to the fibers in the fibrous material. Such fibrous
materials may optionally be used as supporting element for the
abrasive compound that performs the abrasive operation of the
abrasive tool. Thus, a flexible or at least partly non-rigid tool
is provided.
[0071] The loop side may also comprise other types of flexible
materials, e.g., foam-based materials and rubber.
[0072] It has been realized that fastening means based only on hook
and loop arrangements provide high resistance to the shear forces
exerted on tools during abrasive operation, which is an advantage.
However, hook and loop arrangements do not provide very large
resistance to the pull forces which are exerted on tools as the
trowel is lifted from the surface during tool replacement,
especially if the loop-side is constituted by a fibrous material
instead of a conventional `Velcro` loop-side. Such fibrous
materials often provide reduced pull strength compared to
conventional Velcro-like loop side materials.
[0073] The same conclusion holds for a friction based fastening
arrangement based on protrusions. This type of fastening
arrangement provides shear force resistance but very little pull
force resistance.
[0074] A magnetic fastening arrangement, as referred to herein, is
any arrangement which is able to releasably hold one element to
another element by means of a magnetic force exerted by one or both
elements onto the other. Thus, magnetic fastening means comprises
arrangements where one element is configured with electromagnetic
or permanent magnets while the other element is configured with
metal responsive to a magnetic force, such as iron, nickel, cobalt,
or certain rare earth metal alloys such as neodymium. Magnetic
fastening means also comprises arrangements where both elements are
configured with magnets of different polarity, or combinations of
magnetic metals and magnets.
[0075] It has been realized that fastening means based only on
magnetic arrangements are too weak for use with power trowels when
it comes to shear force resistance. This means that, during
abrasive operation, the tool may slide off the tool driver, which
causes interruption of the abrasive operation.
[0076] However, magnetic fastening means do provide the sought
resistance to pull forces which are exerted on the tool as the
trowel is lifted from the surface during tool replacement.
[0077] Also, when magnetic fastening arrangements are used to
complement the friction based fastening arrangement, reduced pull
strength is needed from the friction based fastening arrangement.
Thus, in combination with the magnets, a simple friction based
fastening arrangement based on protruding pins entering a fibrous
material may be sufficient for many grinding applications.
[0078] The tools and tool drivers disclosed herein comprise a
combination of magnetic fastening means and friction based
fastening means, which is an advantage since the combination of
fastening means facilitate tool replacement and at the same time
provide for efficient and robust abrading operation. The
combination of the friction, and magnetic system ensures that the
tool is attached with a strong shear resistance and pull-apart
strength.
[0079] There are disclosed herein combinations of magnetic
fastening means and hook-and-loop based fastening means, as well as
combinations of magnetic fastening means and protrusion based
fastening means. Any of these types are usable with adapter type
tool drivers as illustrated in FIGS. 16A and 16B.
[0080] The combination of magnetic fastening means and friction
based fastening means is especially suited for flexible tools where
a fibrous yielding material, such as felt or the like, is used to
support the abrasive compound.
[0081] As mentioned above, tools and corresponding tool drivers
having a diameter between 7 inches and 25 inches are suitable for
the disclosed techniques.
[0082] A preferred size of the tools and tool drivers disclosed
herein is a diameter of 11 inches.
[0083] Another preferred size of the tools and tool drivers
disclosed herein is a diameter of 14 inches.
[0084] It is appreciated that the disclosed techniques are
applicable also for larger tools and corresponding tool drivers of
up to 48 inches.
[0085] There are disclosed herein arrangements 130, 230 for
abrasive operation by a grinder such as a power trowel 100, 200
comprising at least one, and preferably a plurality of, tool
drivers and a corresponding number of abrasive tools which
facilitate tool replacement and at the same time provide for
efficient and robust abrading operation.
[0086] There are also disclosed power trowels 100, 200 comprising
one or more abrasive tools and/or tool drivers as discussed
herein.
[0087] FIGS. 4A and 4B schematically illustrate a tool driver 400
for a power trowel such as the power trowels 100, 200 discussed
above. At least one magnet 410, preferably a plurality of magnets,
are arranged on the tool driver symmetrically 415 around a
rotational center 416 of the tool driver. Here, a hole is shown in
the center. It is appreciated that this hole 430 is optional, i.e.,
not necessary for the overall function as described herein.
[0088] The disclosed tool driver and tool combinations are suitable
for any planetary grinding system using rotating tools for grinding
or polishing surfaces.
[0089] There is also a protrusion or hook component in a friction
based fastening system 420 arranged on the tool driver. Here the
protrusions or hooks are shown covering the whole tool driver 400
except for the hole 430, but the hooks can just as well cover only
a part of the tool driver.
[0090] Consequently, the tool driver 400 shown in FIGS. 4A and 4B
comprises a combination of a magnetic fastening arrangement 410 and
a friction based fastening arrangement 420 for releasably holding
an abrasive tool to the tool driver. The magnetic fastening
arrangement 410 is configured symmetrically 415 around a rotational
center 416 of the tool driver. It is understood that the magnets
are fixedly attached to the tool driver.
[0091] It is preferred that the hooks cover a symmetric area
centered around the rotation center 416 of the tool driver 400,
such that the tool need not be aligned with the tool driver
angularly.
[0092] FIG. 4B shows a side view along section A-A of the tool
driver 400. The combination of magnetic fastening arrangement 410
and friction based system 420 is shown. The tool driver also
comprises a support structure 440 for attaching to the power source
and for providing structural integrity to the tool driver.
[0093] As discussed above, the friction based fastening arrangement
is adapted to provide increased shear strength during abrasive
operation of the tool, while the magnetic fastening arrangement is
adapted to provide increased pull strength during lifting of the
tool driver. This combination is advantageous in that it
facilitates tool replacement at the same time as it provides for a
robust abrasive operation without interruptions due to tool loss.
It was previously thought that only a hook and loop-based system,
was sufficient for this application.
[0094] The tool driver 400 comprises the protrusion side or hook
side of a friction based fastening arrangement, which is a
preferred configuration. It is however, appreciated that the tool
driver can also comprise the loop side or yielding material
side.
[0095] According to some aspects, the friction based fastening
arrangement is a hook and loop based fastening arrangement on the
tool driver that comprises hooks for holding respective loops on
the abrasive tool. According to some other aspects, the hook and
loop based fastening arrangement on the tool driver comprises loops
for holding respective hooks on the abrasive tool. An example of
such loops is a fibrous pad.
[0096] A friction based fastening arrangement based on pins or
other protrusions extending into a yielding surface material
instead comprises a surface with protrusions configured to engage
with a yielding surface material on the abrasive tool to provide
the increased shear strength.
[0097] As mentioned above, the magnetic fastening arrangement may
comprise a plurality of magnets 410 arranged symmetrically 415
around a rotational center of the tool driver.
[0098] According to other aspects, the magnetic fastening
arrangement comprises a metal element which is responsive to a
magnetic force from the abrasive tool.
[0099] The metal element is thus arranged to be releasably held by
one or more magnets.
[0100] FIGS. 5A and 5B schematically illustrate a tool 500 for a
tool driver such as that illustrated in FIG. 5A.
[0101] FIG. 5A shows an abrasive tool 500 for a power trowel 100,
200. The abrasive tool comprises a combination of a magnetic
fastening arrangement 510 and a friction based fastening
arrangement 520 for being releasably held by a tool driver such as
the tool driver 400 discussed above. The magnetic fastening
arrangement 510 is configured symmetrically around a rotational
center 516 of the tool.
[0102] FIG. 5B shows a side view of the tool 500 along cross
section B-B. The abrasive coating 550 is shown in FIG. 5B, it is
this coating that abrades the material which is to be levelled or
polished. The tool also comprises a support structure 540 which
provides mechanical integrity. The combination of friction-based
fastening means 520 and magnetic fastening means 510 can also be
seen in FIG. 5B. Again, advantageously, the friction based
fastening arrangement 520 is adapted to provide increased shear
strength during abrasive operation of the tool, and the magnetic
fastening arrangement 510 is adapted to provide increased pull
strength during lifting of the tool.
[0103] According to aspects, the friction based fastening
arrangement is a hook and loop system where the tool comprises
hooks for holding respective loops on the corresponding tool
driver.
[0104] According to other aspects, the friction based fastening
arrangement on the tool comprises loops, e.g., a fibrous pad, for
holding respective hooks on the tool driver.
[0105] According to some aspects, the abrasive component on the
tool is supported at least partly by a flexible supporting element,
such as the fibrous pad. Thus, the tool is not necessarily mounted
on a rigid supporting element but may flex and bend somewhat to
follow irregularities in the material to be abraded.
[0106] It is appreciated that the loop side on the abrasive tool
may according to some aspects be implemented by a fibrous material,
such as a felt-like cloth or similar fibrous material, which is a
cost-effective way of producing the tool. It is noted that this
type of felt-like cloth or fibrous material is a yielding material
different from the known Velcro loop-side that is a synthetic
material comprising a special type of loops. Also, the felt-like
cloth or fibrous material constitutes a flexible carrier for an
abrasive material, providing a flexible tool having a yielding
surface material suitable for receiving pins or protrusions of a
friction based fastening arrangement.
[0107] The configuration of magnetic fastening means in FIG. 5B is
a metal band arranged symmetrically around the rotational center
516. It is however, appreciated that magnets can be arranged also
on the tool, albeit with a different polarity compared to the
corresponding tool driver.
[0108] Thus, according to aspects, the magnetic fastening
arrangement comprises a plurality of magnets 410 arranged
symmetrically around a rotational center of the abrasive tool.
[0109] According to other aspects, the magnetic fastening
arrangement comprises a metal element responsive to a magnetic
force from the tool driver.
[0110] A circularly shaped or otherwise rotationally symmetric
shaped magnetic tape can optionally be attached to the fibrous pad
of the tool to provide magnetic attachment force.
[0111] FIG. 6 shows a tool and tool driver combination 600. It is
seen that the magnets 410 align with the metal band 510. Since both
magnets and metal band are arranged symmetrically around the
rotational center of the tool and driver, respectively, there is
always overlap between magnets and metal band, regardless of in
which angle the tool is turned relative to the driver, which is an
advantage since it simplifies tool replacement. It is also noted
that the elements of the friction based fastening means overlap and
thus engage releasably with each other.
[0112] FIG. 6 also illustrates the force direction S of the shear
forces which act on the tool during abrasive operation, and the
gravitational pull forces P which act on the tool when the trowel
is lifted from the surface during tool replacement.
[0113] FIGS. 7A and 7B schematically illustrate centering
means.
[0114] A potential issue relates to a scenario when the tool 800 is
not attached centered with respect to the tool driver 800. If the
tool center does not align with the tool driver center, then
fastening means may not be as effective. For instance, magnets 410
may not contact the metal band 510 with a reduced pull force
resistance as consequence.
[0115] To alleviate this issue, the tool driver 700 comprises
centering means 710 for centering the abrasive tool with respect to
the rotational center 416 of the tool driver.
[0116] The centering means 710 may comprise centering elements
arranged around the circumference of the tool driver as shown in
FIG. 7A. The centering elements only allow the tool to contact the
tool driver if the rotational centers are aligned, otherwise the
tool will not attach. This is an advantage since it simplifies tool
replacement and provides for a more robust abrasive operation with
a reduction in involuntary tool release.
[0117] FIG. 7B shows a side view of the tool driver 700 when
receiving a tool 500. The tool 500 will only attach to the driver
if it passes the centering means 710, which is an advantage.
[0118] Thus, according to aspects, the tools disclosed herein may
comprise centering means 810 for centering the abrasive tool with
respect to a rotational center 416 of the tool driver.
[0119] FIGS. 8A and 8B schematically illustrate other example
centering means. Here, a tap 810 is arranged protruding from the
tool 800. The tap is configured to be received in a corresponding
hole 430 in the tool driver 400.
[0120] FIG. 8B illustrates the tool 800 being attached to a tool
driver 400. Only when the centering means enters the hole 430 can
the tool 800 attach to the driver 400.
[0121] The tap arrangements and centering element arrangements can
be used in combination for additional centering robustness.
[0122] It is appreciated that the magnetic fastening means
discussed above are also providing a centering function, since the
magnets will exert a magnetic force only when aligned with the
corresponding magnetic fastening element on the tool or tool
driver. Thus, a centering action by the magnets follow from the
rotationally symmetric configuration of the magnetic fastening
means.
[0123] FIG. 9 schematically illustrates a tool driver 900 for a
power trowel. This tool driver comprises the loop or yielding
surface component 420 of the friction based fastening means. It is
this appreciated that the friction based fastening means can be
arranged in different ways while maintaining the technical effects
discussed herein.
[0124] The tool driver 900 also comprises a metal band 520 instead
of magnets, this illustrates that magnets and metal band can be
exchanged or switched between tool and tool driver while
maintaining the technical effects discussed herein.
[0125] FIG. 10 schematically illustrates a tool 1000 for a tool
driver. This tool comprises the hook element 520 of a hook and loop
based fastening arrangement, and also the magnets 410. The tool
1000 therefore corresponds to and can be releasably held by the
tool driver 900. The tool 1000 may also comprise protrusions
arranged to engage with a yielding surface material of the tool
driver 900.
[0126] FIG. 11 shows a collection of example magnet shapes 1110,
1120, 1130, 1140. It is appreciated that magnets can have varying
shape and can also be applied as a band 1140 around the rotational
center of any of the tool or the tool driver.
[0127] FIG. 12 schematically illustrates a tool driver 1200 for a
power trowel. This tool driver has a rectangular shape which may be
advantageous in some polishing scenarios.
[0128] FIG. 13 schematically illustrates a tool 1300 corresponding
to the tool driver 1200.
[0129] FIG. 14 is a flow chart illustrating methods. There is shown
a method of attaching a tool 500, 800, 1000, 1300 to a tool driver
400, 700, 900, 1200 for a power trowel 100, 200. The method
comprises configuring S1 a combination of a magnetic fastening
arrangement 410, 510 and a friction based fastening arrangement
420, 520 for releasably holding an abrasive tool 500, 800, 1000,
1300 to the tool driver, wherein the magnetic fastening arrangement
410, 510 is configured symmetrically 415 around a rotational center
416 of the tool driver. The method also comprises releasably
holding S2 the tool by the tool driver.
[0130] FIGS. 15A and 15B schematically illustrate a tool for a
power trowel. The tool is, according to aspects, a pad assembly 10
such as that exemplified in FIGS. 15A-15B. Pad assembly 10 may be
used for grinding or polishing composite surfaces, such as
concrete. Pad assembly 10 includes a wear-resistant base pad 12,
which may be a porous, fibrous, flexible, and deformable material,
including natural and/or artificial fibres. Base pad 12 is
generally circular, having a diameter and a thickness. Of course,
base pad 12 could be made in other sizes.
[0131] A reinforcement ring or layer 14 is secured to one side of
base pad 12, such as by adhesive. The reinforcement ring 14 is
generally annular having a central opening 18 with a diameter (for
example, approximately 8 inches). Reinforcement ring 14 may be a
rigid rubber or plastic having a thickness greater than zero and up
to 0.125 inch. Reinforcement ring or layer 14 reinforces and adds
some stiffness and toughness to the outer portion of pad 12,
however, ring or layer 14 allows some flexibility to pad assembly
10 so it can flex with and follow any floor imperfections thereby
producing uniform floor contact for polishing or grinding.
[0132] A circular internal edge 17 of reinforcement ring 14 defines
a central opening or hole 18 which exposes a central surface 20 of
base pad 12. Central surface 20 of base pad 12 may according to an
example be impregnated with diamond particles or other abrasive
materials. Central surface 20 of the base pad 12 may also be
painted with a colour indicating a quality of the pad assembly 10,
such as the coarseness. Base pad 12 and ring 14 preferably have
circular peripheral surfaces 19 and 21, respectively.
[0133] In the example of FIGS. 15A and 15B, a plurality of abrasive
tools or floor-contacting disks 16 are secured to the outer surface
of the reinforcement ring 14. In the example shown, abrasive tools
16 are approximately 2-inch disks of diamond particles in a
polymeric resin matrix. In the example shown, six such abrasive
tools or disks 16 are secured about the circumference of
reinforcement ring 14. Different sizes and different compositions
of abrasive tools or disks 16 could be used. Tools or disks 16 are
adhesively bonded to ring 14.
[0134] FIG. 15B shows base pad 12. Again, different base pads 12
could be used, but the example shown is a wear-resistant base pad
12 having a diameter of approximately 14 inches and a thickness of
approximately one inch. A metal ring here constitutes the magnetic
fastening means. The metal ring is glued to the upper surface of
the tool. The ring has an outer diameter smaller than the outer
diameter of the reinforcement ring 14.
[0135] To summarize, FIGS. 15A and 15B exemplify an abrasive tool
1500 comprising;
a fibrous pad 12 including an upper surface, a floor-facing lower
surface and a peripheral surface; a reinforcement layer 14 attached
to the bottom surface of the pad, the reinforcement layer including
an internal edge 17 defining a hole therethrough; abrasive disks 16
attached to a floor-facing surface of the reinforcement layer; a
central area 20 of the pad being exposed through the hole of the
reinforcement layer such that a linear dimension of the central
area within the hole is greater than a linear dimension of one side
of the reinforcement layer between the hole and a periphery
thereof; and a magnetic ring 22 arranged on the upper surface which
constitutes the magnetic fastening arrangement, wherein the
magnetic ring has an outer diameter smaller than an outer diameter
of the reinforcement layer 14.
[0136] FIG. 16A schematically illustrates a front side of a tool
driver 1600 configured to attach to an abrasive tool, such as the
tool 1500 shown in FIGS. 15A and 15B. FIG. 16B schematically
illustrates a back side of the tool driver 1600 configured to
attach to a secondary tool driver 2. The secondary tool driver will
be discussed in connection to FIG. 18 below.
[0137] The tool driver 1600 is arranged to interface with the
secondary tool driver 2, thereby assuming the function of an
adapter. By using the tool driver 1600, a tool such as the tool
1500 shown in FIGS. 15A and 15B can be used with existing grinding
machines.
[0138] In the example of FIGS. 16A and 16B, the tool driver 1600
has a magnetic fastening arrangement which comprises front-side
magnets 410 and back side magnets 410' arranged distributed on
respective circles.
[0139] According to some aspects (not shown in FIG. 16A or 16B),
the front side magnets 410 extend through the tool driver, from the
front side to the back side to engage with the abrasive tool on the
front side of the tool driver and to engage with the secondary tool
driver 2 on the back side of the tool driver. In this case the back
side magnets 410' are not necessary.
[0140] According to some aspects, the tool driver 1600 comprises
protruding elements 1610 having shapes matched to corresponding
recesses 4, or fixing means 4, formed in the secondary tool driver
2.
[0141] The tool driver 1600 shown in FIGS. 16A and 16B is
configured with a combination of magnetic fastening arrangement
providing pull strength, while the protruding elements 1605, or
pins, is a friction based fastening arrangement adapted to provide
increased shear strength during abrasive operation of the tool. The
magnetic fastening arrangement 410, 410' is configured
symmetrically around a rotational center of the tool driver.
[0142] The tool driver 1600 may, according to some aspects, also be
configured with the type of hook-and-loop based fastening
arrangement discussed above.
[0143] According to some aspects, one or more notches 1620 are
formed in the rim 1630 of the tool driver. The notches or cut-out
portions allow a finger, hand, or tool to get better purchase when
removing the tool driver from, e.g., a secondary tool driver 2. For
instance, a service technician or operator of a grinding machine
can get purchase on the tool driver by inserting a finger into the
notch 1620.
[0144] FIGS. 17A-17C show additional views of the tool driver 1600.
Note especially the protrusions or pins 1605 and the recesses 1620.
Note also that the pins 1605 are shown as an example, a
hook-and-loop based fastening arrangement can also be used instead
of, or in combination with, the pins 1605.
[0145] FIG. 18 schematically illustrates an example secondary tool
driver 2. The secondary tool driver 2 has a front side and a back
side, which front side is facing the ground during the grinding
process. The secondary tool driver 2 further has a circular opening
6 in the center to guide the disc when attaching it to a grinding
machine. A plurality of screw holes 5 are situated around the
secondary tool driver 2 to be used for tightening of the secondary
tool driver 2 when put into place in a grinding machine. Grooves 7
are distributed radially outwards from the center of the tool
driver 2 and are evenly distributed around the circumference of the
disc. Each groove 7 is of a conical shape tapering radially
outwards from the center of the disc. Two carrier plates will be
attached to a first 3 and a second 4 fixing means in such a way
that abrasive elements of respective carrier plate will overlap
radially. This is accomplished in that the grooves of first 3 and
second 4 fixing means are distributed so that the innermost end 3b
of the first fixing means 3 and the outermost end 4a of the second
fixing means 4 partly overlap each other in the radial direction.
In a preferred way, the innermost second fixing means 4 are
disposed circumferentially in between two adjacent outermost first
fixing means 3 in such a way that the first and the second fixing
means will not extend along the same radial line
[0146] In FIG. 18, the grooves 7 of the innermost second fixing
means 4 are placed in such a way that the innermost end 4b of each
fixing mean opens up toward the opening at the center of the disc
6. In the shown example of FIG. 18, the disc 2 comprises six first
fixing means 3 and six second fixing means 4. However, it is clear
to a person skilled in the art that one disc could comprise
anywhere from two or more fixing means sharing the same
predetermined distance to the center of the disc. Moreover, a
secondary tool driver according to the present disclosure could
comprise more than two fixing means, preferably distributed evenly
around an secondary tool driver to balance the disc, and each
having a certain predetermined distance to the center of a disc
that is different from the distance of any other fixing means on
the same disc. This secondary tool driver 2 and its use was
discussed in detail in EP 2 337 653 B1, where it is referred to as
an abrasive disc. It will therefore not be described in more detail
herein.
[0147] FIGS. 19A and 19B illustrate another example tool driver
1900. This tool driver is similar to the tool driver 1600 shown in
FIGS. 16 and 17, but instead uses wings 1910 having shapes matched
to a secondary tool driver shape. The wings 1910 are protruding
elements having shapes matched to corresponding recesses formed in
the secondary tool driver.
[0148] Similar to the example tool driver in FIGS. 16A-B and FIG.
17A-C, one or more notches 1620 are formed in rim portions of the
wings 1910. The notches or cut-out portions allow a finger, hand,
or tool to get better purchase when removing the tool driver from,
e.g., a secondary tool driver 2.
[0149] The tool driver 1900 shown in FIGS. 19A and 19B is
configured with a combination of magnetic fastening arrangement
providing pull strength, while the protruding elements 1605, or
pins, is a friction based fastening arrangement adapted to provide
increased shear strength during abrasive operation of the tool. The
magnetic fastening arrangement 410, 410' is configured
symmetrically around a rotational center of the tool driver.
* * * * *