U.S. patent application number 11/175931 was filed with the patent office on 2007-01-11 for cutting device.
Invention is credited to Christopher Davies, Nicholas James Mival.
Application Number | 20070006468 11/175931 |
Document ID | / |
Family ID | 37616994 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006468 |
Kind Code |
A1 |
Davies; Christopher ; et
al. |
January 11, 2007 |
Cutting device
Abstract
A cutting device, particularly suited for removing vehicle
glazing panels, has forward blade carrier and a rearward handle
spaced from the forward blade carrier. The forward blade carrier
may function as a handle, the device thereby being operable in two
handed use. The rearward handle and forward blade carrier may be
movable relative to one another permitting re-configuration of the
device. The rearward handle and forward blade carrier may be
connected by a bridge portion. Novel aspects of the blade and
lubrication for the device are also described and claimed.
Inventors: |
Davies; Christopher;
(Kidwelly, GB) ; Mival; Nicholas James; (London,
GB) |
Correspondence
Address: |
JAY P. SBROLLINI, ESQ.;Gordon & Jacobson, P.C.
60 Long Ridge Road
Stamford
CT
06902
US
|
Family ID: |
37616994 |
Appl. No.: |
11/175931 |
Filed: |
July 6, 2005 |
Current U.S.
Class: |
30/294 |
Current CPC
Class: |
B26B 5/00 20130101; Y10T
83/04 20150401; B60J 10/45 20160201 |
Class at
Publication: |
030/294 |
International
Class: |
B26B 29/00 20060101
B26B029/00 |
Claims
1. A cutting device comprising a forward blade carrier and a
rearward handle spaced from the forward blade carrier, the rearward
handle and forward blade carrier being movable relative to one
another permitting re-configuration of the device.
2. A cutting device according to claim 1, wherein the rearward
handle and forward blade carrier are lockable relative to one
another permitting setting of the device in re-configured
orientations.
3. (canceled)
4. A cutting device according to claim 1, wherein the rearward
handle is movable in an arc about the forward blade carrier.
5. A cutting device according to claim 1, wherein the rearward
handle is movable about the forward blade carrier through an angle
that includes at least one of 90 degrees, 180 degrees, 270 degrees
and 360 degrees.
6-9. (canceled)
10. A cutting device according to claim 1, including a lock
arrangement for locking the rearward handle relative to the blade
carrier in a plurality of orientations.
11. A cutting device according to claim 10, wherein the lock means
comprises at least one of: a lock actuator accessible to a user of
the device and a biasing arrangement for biasing the lock
arrangement normally to a locked orientation.
12. (canceled)
13. A cutting device according to claim 4, including a rotatable
mounting at the blade carrier for mounting the rearward handle
rotatably relative to the blade carrier.
14. A cutting device according to claim 1, wherein the blade
carrier includes an external surface portion providing a forward
handle.
15. A cutting device according to claim 1, including a bridge
portion extending between the rearward handle and the blade
carrier.
16. (canceled)
17. A cutting device according to claim 15, including a rotatable
mounting at the blade carrier that provides for rotational movement
of the bridge portion and the rearward handle relative to the blade
carrier.
18. A cutting device according to claim 1, wherein the rearward
handle and the blade carrier extend downwardly from a connecting
bridge portion.
19. A cutting device according to claim 18, wherein the rearward
handle, blade carrier and connecting bridge portion are arranged
such that at least of the following conditions are satisfied: i)
the rearward handle axis, blade carrier and bridge portion lie
substantially in the same plane; and ii) the rearward handle and
the blade carrier are substantially parallel to one another.
20. (canceled)
21. A cutting device according to claim 1, including a blade
adjustment arrangement for adjusting the position of a blade
relative to the blade carrier.
22. A cutting device according to claim 21, wherein the blade
adjustment arrangement comprises at least one of: an actuator
provided on the exterior of the device and a ratchet mechanism
adapted to advance and/or retract the blade relative to the blade
carrier.
23-24. (canceled)
25. A cutting device according to claim 1, wherein the blade
carrier includes at least one of: an internal receiving recess for
receiving a blade and a blade retaining element for securing a
blade to the blade carrier.
26. (canceled)
27. A cutting device according to claim 25, wherein the blade
retaining element is resiliently biased in a retaining
position.
28. A cutting device according to claim 1, including engagement
means for engaging a substrate at a level spaced from the terminal
portion of the blade.
29. A cutting device according to claim 28, wherein the engagement
means is carried by the blade carrier.
30. A cutting device according to claim 28, wherein the engagement
means comprises a rotatable element (preferably a roller).
31. (canceled)
32. A cutting device according to claim 1, further comprising a
blade which includes an elongate mounting portion for mounting to
the blade carrier and a cutting portion extending transversely to
the mounting portion.
33. A cutting device according to claim 32, wherein the cutting
portion of the blade extends transversely to the plane in which the
blade carrier and rearward handle lie.
34. A cutting device according to claim 1, including a lubrication
arrangement for delivering lubricant to a blade carried by the
blade carrier.
35. A cutting device according to claim 34, wherein the lubrication
arrangement includes at least one of: i) a lubricant reservoir
(which is preferably disposed internally of the rearward handle),
ii) delivery means for delivering the lubricant via the blade
carrier to a blade carried therein (which is preferably arranged to
deliver the lubricant to the blade along a path internally of the
blade carrier), iii) a conduit spanning a bridge portion extending
between the rearward handle and the forward handle, iv) a lubricant
injector or nozzle that is part of the blade carrier, which is
arranged to dispense lubricant to a portion of a blade carried
therein, and v) a lubricant delivery actuator that is mounted on
the exterior of the device.
36-42. (canceled)
43. A cutting device according to claim 1, including a blade having
a cutting portion and a fixing portion extending substantially
transversely to the cutting portion.
44. A cutting device comprising a forward blade carrier, a rearward
handle spaced from the forward blade carrier and a bridge portion
interconnecting the forward blade carrier and the rearward handle
which both depend from the bridge portion, the forward blade
carrier providing a forward handle for the device, the forward
blade carrier, rearward handle and bridge portion being in
substantially the same plane.
45-51. (canceled)
52. A method of removing a vehicle windscreen or other structural
panel or element comprising: providing a cutting device including a
forward blade carrier and a rearward handle spaced from the forward
blade carrier, the rearward handle and forward blade carrier being
movable relative to one another permitting re-configuration of the
device, and manually manipulating the forward blade carrier and
rearward handle to apply force to the device to cut the windscreen
or other structural element with the blade of the device.
53-59. (canceled)
Description
[0001] The present invention relates to a cutting device and in
particular to a hand held cutting device, primarily a cut-out tool
for use in cutting bonding materials such as polyurethane bonding
material. Bonded panels (vehicle or the like) may be released by
using the device at perimeter accessible bonded zones of the panel.
In particular, the device of the invention is particularly suitable
for use in cutting or paring polyurethane bonding material used to
bond vehicle panels such as vehicle windscreens in vehicle
windscreen openings.
[0002] According to a first aspect, the present invention provides
a cutting device comprising a forward blade carrier and a rearward
handle spaced from the forward blade carrier, the rearward handle
and forward blade carrier being movable relative to one another
permitting re-configuration of the device.
[0003] Preferably, the rearward handle and forward blade carrier
are lockable relative to one another permitting setting of the
device in re-configured orientations.
[0004] The forward blade carrier typically acts as a forward handle
for gripping by one of the user's hands. The rearward handle is
gripped by the other of the user's hands. The spaced separate
handles ensure that the device is ergonomically attractive and
efficient to use.
[0005] Because the rearward handle can be moved to be reorientated
relative to the forward blade carrier/handle, the device is
convenient to use around corners or bends such as around the
peripheral corner of a vehicle windscreen when the device is used
for removing vehicle windscreens. Because the device locks in its
reorientated configuration, the device is sturdy and safe for
use.
[0006] Typically the rearward handle is moveable in a planetary
orbit (rotationally) about the forward blade carrier. The rearward
handle is preferably moveable through substantially 90.degree. or
more (more preferably 180.degree., or more preferably still
270.degree.) about the forward blade carrier.
[0007] The rearward handle is arranged to be locked in a plurality
of orientations relative to the forward blade carrier. The device
preferably includes a lock arrangement for this purpose. The lock
arrangement beneficially comprises a lock actuator accessible to
the user of the device. Beneficially a biasing arrangement is
provided for biasing the lock arrangement normally to the locked
position.
[0008] In order to facilitate the orbital movement of the rearward
handle about the forward blade carrier, a rotatable mounting is
beneficially provided at the blade carrier.
[0009] A bridge portion is typically provided extending between the
rearward handle and the blade carrier, the bridge portion
beneficially being arranged to move in unison with the rearward
handle about the blade carrier. The bridge portion and rearward
handle are typically effectively integral with one another. The
forward end of the bridge portion is typically mounted rotatably at
a rotatable mounting at the blade carrier. The rearward handle and
the blade carrier depend downwardly from the bridge portion and
preferably lie in substantially the same plane. The rearward handle
and blade carrier are therefore substantially parallel (or have
substantially parallel axes).
[0010] The device preferably includes a blade adjustment
arrangement for adjusting the position of the blade relative to the
blade carrier. The blade adjustment arrangement is beneficially
adjustable by means of an actuator provided on the exterior of the
device. The arrangement is actuatable to selectively vary the
projecting distance of the blade from the blade carrier. In one
embodiment, the blade adjustment arrangement may include a ratchet
mechanism to advance and/or retract the blade relative to the blade
carrier.
[0011] Typically the blade carrier includes an internal receiving
recess for receiving the blade. A blade retaining element is
beneficially provided for securing the blade with the blade
carrier; the blade retaining element is beneficially resiliently
biased to a retaining position.
[0012] The device may include engagement means for engaging a
substrate at a level spaced (upwardly) from the terminal portion of
the blade. For example where the device is used for removing
vehicle windscreens, the engagement means will engage the external
surface of the windscreen proximate the peripheral edge thereof.
The cutting portion of the blade is inserted through the bonding
material on the underside surface of the windscreen. The engagement
means is beneficially carried by the blade carrier and beneficially
comprises rotatable engagement means such as for example a roller.
As an alternative, a ski-or skid may be provided.
[0013] The cutting blade typically comprises an elongate mounting
portion for mounting to the blade carrier and a cutting portion
extending substantially transversely to the mounting portion.
[0014] The cutting portion of the blade beneficially extends
transversely to the plane in which the blade carrier and rearward
handle lie. Beneficially the cutting portion of the blade tapers to
an apex.
[0015] It is preferred that the device includes a lubrication
arrangement for delivering lubricant to the blade. Beneficially the
lubrication arrangement includes a lubricant reservoir which is
preferably provided internally of the rearward handle. Lubricant
delivery means beneficially delivers the lubricant along the blade
carrier to pass to the blade. The delivery means is beneficially
arranged to deliver the lubricant to the blade along a path
internally of the blade carrier. It is preferred that the lubricant
delivery means includes a conduit spanning the bridge portion of
the device. A lubricant injector or nozzle is beneficially provided
for the blade carrier arranged to dispense the lubricant to the
region of the blade. A lubricant delivery actuator is preferably
mounted on the exterior of the device being actuatable preferably
to pump the lubricant fluid.
[0016] According to a further aspect the invention provides a
cutting device comprising a forward blade carrier, a rearward
handle spaced from the forward blade carrier and a bridge portion
interconnecting the forward blade carrier and the rearward handle
which both depend from the bridge portion, the forward blade
carrier providing a forward handle for the device, the forward
blade carrier, rearward handle and bridge portion being in
substantially the same plane.
[0017] According to a further aspect the invention provides a
cutting device comprising a blade carrier, an engagement
arrangement (such as a roller, for example) for setting the device
against a surface, and a blade adjustment arrangement for adjusting
the position of the blade relative to the blade carrier and/or the
engagement arrangement.
[0018] According to a further aspect the invention provides a
cutting device comprising a blade carrier and an engagement
arrangement (such as a roller, for example) for setting the device
against a surface such that the blade cuts at a predetermined cut
plane relative to the engagement arrangement.
[0019] According to a further aspect the invention provides a hand
held cutting device comprising a blade carrier and a lubrication
arrangement for delivering lubricant to the blade via the blade
carrier.
[0020] Preferred features of the invention as defined in these
aspects are in accordance with preferred features of the invention
as defined in accordance with the first mentioned aspect
herein.
[0021] According to a further aspect, there is provided a blade for
a cutting tool, the blade including a tapered cutting portion
having opposed tapering cutting edges terminating at an apex
portion of the blade, wherein: [0022] i) at least one of the
tapering cutting edges has a cutting edge bevel defining an angle
of substantially 40.degree. or less; and/or [0023] ii) both opposed
tapering cutting edges have a cutting edge bevel; and/or [0024]
iii) at least one of the tapering cutting edges has a cutting edge
bevel on upper and lower portions of the blade defining a double
bevel.
[0025] Beneficially at least one of the tapering cutting edges has
a cutting edge bevel defining an angle of substantially 30.degree.
or less (more preferably substantially 25.degree. or less)
[0026] It is preferred that both tapering cutting edges have a
substantially corresponding degree of taper. Preferably both
opposed tapering cutting edges have a substantially corresponding
cutting edge bevel angle. In a preferred embodiment, both opposed
tapering cutting edges have a substantially corresponding double
bevel.
[0027] It is preferred that the blade includes a fixing portion
extending in a direction substantially perpendicular to the tapered
cutting portion, the fixing portion being configured to facilitate
fixing to a tool or the like.
[0028] The invention will now be further described in specific
embodiments, by way of example only, and with reference to the
accompanying drawings, in which:
[0029] FIG. 1 is a perspective view of a first embodiment of
cutting device in accordance with the invention;
[0030] FIG. 2 is a side view of the cutting device of FIG. 1;
[0031] FIG. 3 is a front end view of the device of FIGS. 1 and
2;
[0032] FIG. 4 is a schematic sectional view (along A-A in FIG. 3)
of the device of the preceding Figures;
[0033] FIG. 5 is a schematic sectional view (along B-B in FIG. 2)
of the device of the preceding Figures;
[0034] FIG. 6 is a schematic plan view of the device of the
previous Figures;
[0035] FIG. 7 is a side view of alternative cutting device
generally similar to the apparatus of FIGS. 1 to 6;
[0036] FIG. 8 is a schematic sectional view showing the cutting of
a bonded joint, in particular a windscreen or other element, bonded
to a support surround by means of a polyurethane bonding bead.
[0037] FIG. 9 is a schematic plan view of a test blade in
accordance with the invention;
[0038] FIG. 10 is a schematic sectional view along C-C in FIG. 9
for a first embodiment of blade;
[0039] FIG. 11 is a sectional view along C-C in FIG. 9 for a second
embodiment of blade;
[0040] FIG. 12 is a graphic representation of force encountered in
using the blade of the invention;
[0041] FIG. 13 is a plot showing the force encountered in a test
procedure involving various blades;
[0042] FIG. 14 is a table of test results;
[0043] FIG. 15 is a schematic perspective view of a modified
embodiment of cutting device in accordance with the invention;
and
[0044] FIG. 16 is a detailed, part sectional view of the embodiment
of FIG. 15.
[0045] Referring to the drawings, there is shown a cut-out device 1
particularly suited for cutting operations such as cutting, paring
or slicing bonding material 50 (typically polyurethane) bonding
structural panels, such as for example a vehicle windscreen 51 to a
vehicle windscreen opening 52.
[0046] The cut-out device 1 has a forward blade support handle 2
and a rearward handle 3 spaced from the forward blade support
handle 2 by a bridge portion 4. Forward blade support handle 2
includes rubber grip pads 5a, 5b and rear handle 3 includes ruber
grip pad 6 for enhanced ergonomic action and efficiency of use.
[0047] The forward blade support handle 2 acts as a housing and
fixing for an `L` shaped cutting blade 7 which has a laterally
projecting cutting portion 7a tapering to an apex, and an upwardly
projecting fixing length 7b. As shown most clearly in FIG. 5, the
fixing length 7b of the blade 7 is received in an internal guide
and receiving channel 9 provided in the forward handle 2. The
fixing length 7b includes a circular aperture through its thickness
dimension into which nestles a projection 8a of a quick release
blade fixing leaf spring 8. Leaf spring 8 is fixed at its proximal
end 10 and includes a manually accessible tab 11 at its distal end
which may be moved outwardly to disengage the projection 8a from
engagement with the fixing length 7b of the blade. The leaf spring
8 is normally biased to the engagement position as shown in FIG.
5.
[0048] The distal portion of the blade support handle 2 carries a
guide roller 12 mounted on a shaft 13. The projecting cutting
portion 7a of the blade 7 is below the level of the perimeter of
the roller 12. In use, the roller 12 sits on the surface of the
windscreen 51 such that the blade cutting portion 7a passes through
the polyurethane bonding material 50 present between the windscreen
and the support frame 52 of the vehicle windscreen opening. The use
of a roller provides good low fiction contact and aids in the ease
of use of the device. As an alternative a ski or skid arrangement
could be used in place of a roller.
[0049] This arrangement provides consistent depth or level of cut
of the bonding material as the device is moved about the
windscreen. A further feature of the device is the ability to
select the depth of cut required by means of adjusting the level of
the projecting cutting portion 7a of the blade with respect to the
roller 12.
[0050] A blade depth adjustment arrangement is accordingly
incorporated into the device including a manually accessible button
15 which is depressed in order to increase the depth of cut
performed by the blade. The button 15 when depressed advances the
blade carrier 16 to increase the spacing of blade portion 7a below
the lower most portion of roller 12. A quick release ratchet
mechanism 17 including biasing springs 18, 19 acts to enable
restoration of the blade carrier 16 and blade 7 to a datum
orientation when removed from cutting the polyurethane bonding
material.
[0051] In order to further facilitate the bonding material cutting
process the device includes the facility to deliver a cutting
lubricant to the location of the cut. The lubricant is delivered
internally of the forward handle 2 passing down the fixing portion
blade length 7b to the cutting portion 7a. The rear handle 3
includes an internal lubricant reservoir 20 which may be filled via
a filling port closed by a stopper 21. A finger or thumb actuated
lubricant release button 22 is provided for a pump actuator 23
which pressurises the fluid in the reservoir 20 causing lubricant
to be pumped from the reservoir along a flexible lubricant tube 24
extending internally along the length of the bridge portion 4 to
connect with an injector 25 provided internally of the forward
handle 2. The lubricant is dispensed from the injector via an
internal channel 25 along the fixing length 7b of the blade to be
delivered to the cutting portion 7a.
[0052] The arrangement of the forward and rear handles 2, 3 and
connecting bridge 4 in the same plane (force application plane) and
the transverse arrangement of the blade provides a force
application plane which is parallel to the cutting plane direction,
resulting in a highly efficient cut.
[0053] In order to enable the device to be operated to cut around
the corners of the windscreen (or other bonded panel), the device
includes the facility for the rear handle 3 and bridge 4 to pivot
or rotate about the forward handle 2. A collar 27 forms a forward
part of the bridge portion 4 and is bushed to rotate about a boss
28 comprising the forward handle 2. The boss 28 includes a series
of shaped recesses 29 shaped and dimensioned to receive, in mating
engagement, a spigot 30 attached to a forward portion of a locking
bolt 31. Typically the shaped recesses 29 are provided at angular
positions 0.degree. and 180.degree. about the boss at least. Such
recesses may be provided at 90.degree. intervals or narrower
angular spacing. Spacing at 0.degree. and 180.degree. enables the
handles 2, 3 to lock together at rotationally mirrored positions
(see the position of bridge 4a and 4b in FIG. 6) enabling the
apparatus to be manoeuvered easily about the corner of a windscreen
or window pane. The locking bolt 31 is normally biased to an
advanced position by means of a spring 32. A finger retractable
trigger 44 presents through a slot in the bridge portion 4 to
enable the bolt 31 and spigot 30 to be retracted so as to permit
rotation of the rear handle 3 and bridge portion 4 about the
forward handle 2. The lubricant tube 24 passes through an annular
space 38 enabling the tube to swing through the required angular
sweep as the handle 3 and bridge portion 4 rotate. The tube 24
presses against rib 47 when the pump button 2 is pressed to aid
pumping of the lubricant.
[0054] The rear handle 3 may be held clear of the windscreen
surface or alternatively may be provided with contact means to
contact the windscreen surface. Such contact means may for example
be a roller ball 48 or the like. The provision of a roller ball 48
contact at the base of the rear handle 3 assists the operator to
maintain a direction of pull and push force on the device which is
parallel to the blade cutting direction. With the aid of pressure
on the glass from the handle 3 by the operator and point contact on
the screen (with 4 degrees of freedom) provided by the roller ball
48, irrespective of the direction of the resultant force applied by
the operator, the horizontal component of the force will always
remain parallel to the glass screen surface. The device also
provides rigid parallelogram frame thus insuring minimisation of
the force components which are not in line with blade cutting
direction. Consequently there is minimal tilt of the blade cutting
portion 7a and therefore minimal friction and resistance which
would otherwise occur due to non-optimisation of cutting angle.
This results in less effort required in the cutting process. In
addition, the roller ball provides ergonomic benefits enabling
maximum force to be applied by the user's arms and shoulders
independent of the orientation of the remainder of the user's body.
An additional benefit of the device is increased manoeuvrability
providing ease of movement around the corners and at the point of
insertion of blade cutting portion 7a at the start of the cutting
process.
[0055] As an alternative to a roller ball 48 arrangement, a ski or
skid arrangement may be provided as contact means for the rear
handle 3.
[0056] In use, the rear handle 3 and bridge 4 are rotated about the
forward handle 2 by 90.degree. from the position shown in FIG. 1
such that the cutting portion 7a of the blade 7 points away from
the rear handle 3 with the blade apex in alignment with the rear
handle 3 bridge portion 4 and forward handle alignment plane. In
this configuration, the user can grip the device solidly with both
hands and make an insertion cut into the polyurethane bonding
material with the apex of the cutting portion 7a of the blade 7.
This facility enables controlled and accurate user positioning of
the blade for the insertion cut and application of maximum user
force or insertion in a controlled manner. In addition to producing
a technically accurate blade insertion, user safety is also
maximised.
[0057] With the blade 7a now embedded in the polyurethane bonding
bead 30 as shown in FIG. 8), the rear handle 3 and bridge 4 are
rotated back through 90.degree. to the configuration shown in FIG.
1. The device 1 can then be operated in an ergonomic two handed
fashion by the user, the blade 7a being dragged through the bonding
bead 30 to separate the windscreen 31 (or other panel or element)
from the support surround 32. The depth of cut can be altered
manually by the user using the blade height adjustment facility of
the device (button is and associated corner 16 and ratchet
mechanism 17). The cutting portion 7a of the blade can be
lubricated with lubricant in the manner described above at the
discretion of the user.
[0058] In order to pass around an edge of the windscreen whilst
cutting, the user disengages the spigot 30 from engagement with a
respective recess 29 and rotates the rear handle 3 and bridge 4 by
180.degree. about the forward handle 2 and once again locks the
handles 2, 3 and bridge 4 in a locked orientation permitting the
tool to be continued to be dragged about the screen.
[0059] The cut out device of the invention provides significant
benefits in terms of ease and accuracy of use, quality of cut
achieved and speed of operation. In addition, health and safety
benefits are observed for the user. Specific benefits and
advantages are described hereafter.
[0060] The device provides a manual tool for hand held operation,
having a blade where the cutting edge is maintained parallel to the
windscreen and user body such that minimum cutting force and
minimum friction is experienced. The parrallegram double handle
ensures an ergonomic orientation which provides an optimum
condition for transmission of force from the user's shoulder and
elbows to the tool which is in turn transmitted to the cutting edge
of the blade.
[0061] The device ensures the cutting plane and force application
plane is maintained in parallel through effectively controlled
device adjustment features and a flexible guiding system. Also the
use of a roller and/or roller ball minimises any adverse friction.
The rigid structure of the handles and bridge requires a change of
orientation in order to cut around corners or bends which is
achieved by an axial rotation of the rear handle and bridge in
relation the forward handle blade holder arrangement. The trigger
44 is retracted to facilitate release of the rotation lock enabling
rotation up to 360.degree. in a controlled manner with pre-set
friction. The arrangement is capable of pre-set locking at
0.degree. 180 or other angles as the user may require.
[0062] The cutting height of the blade 7a is determined and
selected by the user for example to leave a predetermined amount of
residual bonding material present. The blade quick release system
enables replacement of blade with ease, whilst maintaining the
correct stiffness for cutting operation.
[0063] The use of liquid lubricant dispensed at correct time and
location to reduce the friction between the blade and the
polyurethane has proven to reduce effort. Furthermore when applied
with the blade in parallel to the cutting surface, combined with
less force, such reduction in friction results in lower required
cutting force. The lubricant dispensing system may be provided as a
disposable item, which enables easy replacement.
[0064] Certain novel and inventive features of blade design
particularly suited to the use of the present invention have also
been developed. FIG. 9 shows a cutting blade 7 having a cutting
portion 7a tapering to an apex 61 and including a pair of opposed
tapering cutting edges 7g, 7f each having a respective cutting edge
bevel angle A, B. In production versions of the blade, the blade 7
is bent to a right angle to have fixing portion 7b and cutting
portion 7a extending in mutually perpendicular directions. For the
purposes of testing, the blade 7 was used in a flat, unbent
condition. The tapering edges 7g, 7f are bevelled such that the
bevels merge at the apex 61.
[0065] Referring now to FIGS. 15 and 16 there is shown an
alternative embodiment of cut-out device 100 which is generally
similar in most constructional and operational aspects to the
earlier described embodiment. In this embodiment the roller 12 is
replaced by a forward support skid 112 and a blade quick
release/quick change arrangement 110 is provided.
[0066] For the blade quick release arrangement 110, an externally
accessible button 101 is biased by a spring (not shown) to urge
hook 102 to an engagement position in which it is received within
an aperture 103 through a tang 104 of an L-shaped cut-out blade
105. Urging the release button 101 downwardly against the biassing
spring enables the tang 104 of blade 105 to be retracted from the
space between wall 106a, 106b of the blade housing 106. The hook
102 pivots about a bulbous end 102b and the locating hook end 102c
is provided with chamfered portions permitting the blade to be
inserted and retracted and engage with the aperture 103.
[0067] In order to evaluate the cutting forces when using the blade
7 in the windscreen cut-out 1 tool a trial was implemented using
standard silicon rubber test media and test blades manufactured
with differing sharp edge geometry.
[0068] Test blades were jigged on a servo driven slide providing
blade speed and positional control. The silicon rubber test media
used was in the form of 8 mm square section extrusion 64 of
70-shore hardness, and treated to achieve consistent properties.
The rubber 64 was mounted on a platform load cell in a former which
presented a concave shape towards the blade as this was thought to
increase the tendency for the rubber to grip the blade. In plan
view (see FIG. 9) the rubber 64 was aligned 8 mm from the apex 61
of the blade 7 so that it would be cut in the middle of what would
be the working area of the cranked end of a production blade. The
attitude of the centreline of the blade was normal to the direction
of travel and thus the reaction force between the rubber and blade
would be measured by one of the orthogonal axis of the load cell. A
PC was used to control the motions of the blade (i.e. slide) and
also to capture the load cell data. Before tests commenced the load
cell/conditioning amplifier and software data routine were
calibrated and sensitivity set to enable full-scale output of the
amplifier at 500N.
[0069] 1.25 mm thick 0.8% C steel was readily available from which
to manufacture the test blades. For convenience the test pieces
were made flat and the ground edges were produced after hardening
and tempering to 50 Rc. Sharpened bevels were produced one side at
a time using a general purpose wheel on a tool room surface
grinder. For this trial 20.degree. angle would be the minimum due
to the thinner material and the increased bevel width. The line of
intersection of these reaches further back from the tip and
actually results in a reduction of blade thickness along this
slope. Four samples of single and double bevelled profiles with
50.degree., 40.degree., 30.degree. and 20.degree. included angles
were tested.
[0070] A cutting stroke of 18 mm was used to ensure the entire
blade cut completely through the media and at a speed of 20 mm/sec.
As a consequence of this a force curve similar in shape to that in
FIG. 12 was obtained. The rising force to the first peak is the
result of a build up of the compressive force between rubber and
blade cutting edge until the point where the rubber is actually
penetrated (the peak). From this point there is a slight reduction
to the beginnings of a plateau area where some or the entire blade
is enclosed by the rubber. Next follows a decay as the blade exits
the rubber.
[0071] As a measure of the initial sharpness of the blade the peak
force reading was recorded. 9/10 cuts per blade were carried out
and the peak force recorded on cuts 1, 2, 5, 9. This was a
precautionary measure to see whether the first readings may be
affected by burrs produced when grinding. For additional comparison
the 50 double sample was then re-sharpened at 30.degree. included
angle using a sharpening machine, which has spiral-interlocking
wheels and grinds both sides simultaneously. This was then tested
along with a straightened out WIZ blade. FIGS. 13 and 14 show the
results obtained.
[0072] The forces measured on each blade showed reasonably good
correlation. There was little adverse affect from burrs. Each blade
demonstrated a slight fall off in measured peak force over the 9
cuts. Generally the blades in each series were ranked according to
included angle and angle for angle double bevels lower forces than
single, with the exception of one anomaly the 20.degree. double
blade. These results are sufficient to show that a double bevelled
shallower angled blade will have a lower cutting force than the
current production (45.degree. single)
[0073] Various aspects of the invention have been primarily
described in relation to a cut-out device for use in removal or
releasing of vehicle windscreens bonded in a vehicle windscreen
opening by an interposed polyurethane bonding bead. It will be
appreciated that the invention has applicability in other
situations for example in paring or refresh scraping polyurethane
or other plastics material or for example in removal of
architectural window panes or other panels or components bonded to
substrates by peripherally accessible bonding material.
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