This invention relates to machines for cutting card, board
and the like materials. Such machines are used, for
example, by picture framers, designers, artists,
photographers and the like. Among the uses of such
machines are the reduction of large sheets of card to
smaller sizes and the cutting of apertures therein,
whether with bevelled or square-cut edges. Machines of
this kind will be referred to, herein and in the claims,
as cutting machines of the kind set forth. It is to be
understood that this definition is not to be limited to
the provision of bevel cutting or other features which may
be needed for particular applications falling within the
uses mentioned above. Machines of the kind set forth
above may include a base board to support card, board and
the like to be cut, together with a clamp bar extending
across the base board to clamp the materials to be cut.
A cutter head may be mounted on the cutter head for
lengthwise sliding movement with respect thereto to cut
the materials. Some aspects of the invention also relate
to other material treatment or positioning or measurement
machines, particularly those having an extruded slideway
on which a slider or slidehead is slidable.
There is disclosed in our prior patents US-A-4 941
380 and GB-A-2 215 654 a cutting machine of the kind set
forth in which the cutter head is mounted on the clamp bar
for lengthwise sliding movement by means of a projecting
wedge member on the cutter head and a complementary wedge-shaped
slot on the clamp bar to receive same. Additional
bearing surfaces are provided by generally flat and
upwardly/downwardly facing surfaces on the clamp bar and
the clamp bar head. Additionally, sliding locating means
is also provided.
While the cutter head guidance and bearing system
as disclosed in the above-mentioned GB 654 specification
has much to commend it and has been commercially
successful, we have identified a need for further
technical improvements notably in relation to simplifying
and reducing the number of components produced for these
functions, and to improve the system for lateral and
longitudinal guidance while avoiding the possibility of
unacceptable tolerances and backlash and to take account
of the fact that the guideway (or clamp bar), which
usually is manufactured as an aluminium extrusion, does
not present to the guide member (or cutter head) a
completely straight lengthwise plan view profile. The
existence of imperfections in the linearity of the clamp
bar/guideway leads to occasional corresponding
imperfections in the free sliding movement of the cutter
head.
A further aspect of the invention relates to
providing improvements in relation to the system disclosed
in our prior patents concerning calibration of the stop
and other gauge systems for the cutter, whereby the cutter
is set for a pre-determined location and length of cut in
relation to the sheet material to be cut. We have
identified a need for improvements in relation to the
existing system for calibration of the stops and other
guides so that these are easy to use and capable of
offsetting user errors and capable of accommodating error-feedback
data and of maintaining a setting once set
correctly. Also, there is a need to be able to adapt for
and accommodate the effect of bevel cuts produced when the
cutter acts non-vertically, such bevel cuts being affected
in terms of their dimensions by the thickness of the board
or other material being cut.
SLIDEWAY BEARINGS
An object of a first aspect of the present invention
(relating to Slideway Bearings) is to provide a cutting
machine of the kind set forth providing improvements in
relation to one or more of the aspects thereof discussed
above concerning guidance and support for the cutter head,
and/or improvements generally therein.
According to this first aspect of the invention
(relating to Slideway Bearings) there is provided a
cutting machine of the kind set forth as defined in claims
14 to 18 and 19 to 27 of the accompanying claims.
In one embodiment of this aspect of the invention
there are provided co-operating guide means on the clamp
bar and the cutter comprising a lengthwise-extending
guideway on the clamp bar and a guide member on the cutter
head. The guideway and guide member have complementary
tapering profiles providing bearing surfaces. These
tapering surfaces on the guideway and the guide member
comprise at least one flexible bearing element mounted so
that at least a portion thereof is capable of being flexed
towards its co-operating bearing surface for adjustment
purposes. In the embodiment, the portion which is capable
of being flexed comprises an end portion of the bearing
element, indeed both end portions of the bearing element
are flexible and the portion therebetween is fixedly
mounted. The bearing element is formed of a polymeric
material whereby its flexibility enables it to provide a
corresponding adjustment function in a very sinmple manner
by means merely of the provision of adjustment screws.
The feature of the flexibility of the bearing
element arising from its polymeric construction and its
associated fixed mounting at a location spaced from the
flexible portion enables the bearing element to provide
for very simple adjustment of the bearing itself merely
by provision of corresponding adjustment screws, while
nevertheless offering a highly; effective bearing system
capable of accommodating tolerances introduced by the
extrusion manufacturing process in combination with the
provision of very adequate bearing surface areas for
relatively long bearing life.
Also in an embodiment of the invention there are
provided cooperating guide means on the clamp bar and the
cutter head comprising a lengthwise extending guideway
on the clamp bar and a guide member on the cutter head,
the guideway and the guide member having complementary
profiles. These profiles provide lateral guidance of the
cutter head and are disposed so that loading the cutter
head in a cutting direction tends to caused reduced
loading of the bearing surfaces provided by the
complementary tapering profiles. In other words, in the
embodiment, the downward hand loading of the cutter head
by the user is in a direction such that the tapering
profiles are urged in a direction reducing their face-to-face
loading. The main bearing surface resisting the
downward loading on the cutter head is, in the embodiment,
provided by simply face-to-face contact of generally
vertically disposed bearing surfaces directed directly
below. The tapering and laterally-guiding bearing
surfaces are disposed on opposite sides of the slideway.
In addition, in the embodiments, and this feature
is by way of complement to the above-described disposition
of the tapering bearing surfaces, there is provided
adjustment means to adjust at least one of the tapered
bearing surfaces to adjust the loading of that bearing
surface. In the embodiment, simply screw threaded
adjustment means is provided for this purpose. It can now
be seen that such adjustment complements the feature of
the disposition of the bearing surfaces, whereby in use
the entire downward load on the cutter head is slideingly
resisted by the cutter head main (and horizontal) bearing
surfaces, while the laterally-guiding bearing surfaces can
be nicely adjusted so as to maintain free sliding contact
without any backlash which would allow for irregularities
in the resultant cutting line in use.
An additional feature of the described embodiments
relates to the features whereby the cutter head lateral
guidance system is able to accommodate and tolerate those
irregularities in linearity of the extruded clamp bar
which arise from its extrusion-type manufacture. Thus in
the embodiments, the bearing elements for providing
lateral guidance of the cutter head are formed with a
relieved region separating lengthwise-spaced bearing areas
so that continuous sliding bearing contact with the clamp
bar (or guideway) is not required. In simple terms, the
relieved region is able to accommodate the non-uniform
portion of the clamp bar whereby the latter passes
smoothly between the bearing areas and, again uniformity
of the cutting line is ensured with an absence of
discontinuities.
A further feature of the embodiments concerns a
simple method for adjustment of the bearing system
lateral guidance for the cutter head. It is only
necessary to adjust the bearing element at one side of the
guideway and not at both sides. For this purpose, that
bearing element has attachment means securing it to the
cutter head in its central region, while leaving its end
regions (which actually make sliding contact with the
guideway, at each side of the central relieved region)
free to be adjusted by simple screw threaded means. Thus,
the relevant one of the bearing elements is centrally
mounted in its relieved region and is provided with simple
screw threaded adjusters for its end bearing regions,
which adjust and readily take up the level of adjustment
needed under cutting loads incurred during use.
Likewise in the embodiment the generally truncated
triangular profile of the bearing elements (whereby they
have parallel base and upper surfaces) enables them to
provide both the lateral guidance and the vertical load
bearing functions simultaneously at the requisite
laterally spaced locations, thereby achieving a further
simplification in function and construction.
BEARING RELIEF
A further aspect of the invention provides a cutting
machine of the kind set forth as defined in claims 28 to
32 of the accompanying claims, and in embodiments of this
aspect of the invention described below there are provided
relieved portions in the tapering bearing surfaces of the
guideway on the clamp bar and guide member on the cutter
head whereby the relieved portion is capable of
accommodating a degree of mismatch of the tapered profiles
arising from, for example, tolerances introduced during
manufacture by extrusion. The relieved portion allows a
degree of, effectively, angular movement of the main
sliding sub-assemblies of the apparatus whereby bearing
surfaces which (due to angular mismatch) might otherwise
make effectively almost line contact can come into proper
face-to-face contact across at least a substantial portion
of their intended operating width.
STOPGAUGE CALIBRATION SYSTEM
Turning to the second aspect of the present
invention, relating to the system for calibration of the
cutter stops and other gauges, the requirements for such
a system have been identified above and in accordance with
this aspect of the present invention there is provided a
cutting machine and/or a calibration machine or device
therefor, as defined in claims 1 to 13 of the accompanying
claims.
In an embodiment of this aspect of the present
invention there is provided a calibration device for a
stop or other gauge on the cutting machine where an
indicator and a measurement scale adjust relative to each
other so as to adjustably indicate the value of a
dimension selected for the cutting machine. Manual
adjustment means is adapted to adjust the relative
positions of the indicator and the scale to permit
selective compensation or offset for detected errors in
the resultant cut dimension produced by the cutting
machine, and the calibration device comprises calibration
indication means whereby a measure is provided of the
extent of the compensation or offset provided frcm a
predetermined or nominal zero position.
By providing calibration indication means which
effects associated relative movement between a calibration
scale and an indicator therefor so as to indicate the
extent of the calibration movement, there is provided the
advantage of enabling in a very simple and straightforward
way a measure to be obtained of the extent of calibration
effected. This is of practical significance when a
machine of the cutting kind is adjusted so as to
compensate for a detected undercut or overcut produced
when commencing a planned cutting production run. If it
is found that a first adjustment or calibration of the
cutting device does not produce the exact result required,
it is at a minimum desirable and sometimes essential to
know the extent of the previous adjustment so that a
suitable correction can be made, whether by way of
increase or decrease of the adjusted cut dimension.
Similar factors arise in relation to use of a given
cutting machine by different persons whose ocular and
other attributes lead to readily-determined, but different
calibration settings for their own accurate use of the
equipment. Such settings can be readily returned to in
the embodiments of the invention.
Likwise, in relation to the cutting of board and
other materials with bevelled edges, there is a
complicating factor in the accurate setting of the cutting
machine arising from the actual thickness of the board to
be cut, whereby the angle of the bevelled cut and the
thickness of the material cut significantly change the
effective resultant dimensions of a given cut. This leads
to a need for a corresponding calibration of the equipment
in a readily reproducible way. The embodiments of the
invention meet this need by enabling numerical recordal
of the corresponding calibration settings accordingly.
In the embodiments of the invention the arrangement
is such that the adjustment device which effects
calibration movements is arranged to effect simultaneous
adjusting movement both of a calibration extent-indicating
member and of a corresponding calibration member for the
measurement scale. These are formed as a common movable
structure having two limbs disposed generally parallel to
each other and likewise parallel to the calibration and
measurement scales. As a result, an extremely simple
finger-operated adjustment device can be provided with a
compression spring to effect frictional resistence to
unintended adjustment once a setting has been reached.
Embodiments of the invention will now be described
by way of example with reference to the accompanying
drawings in which:
Figs 1, 2 and 3 show aspects of the cutting machine
disclosed in our prior UK patent GB-A-2 215 654, Fig 1
showing a general perspective view of the machine, Fig 2
showing a section through the cutter head taken in the
plane II-II in Fig 1 and Fig 3 showing a close-up
perspective view of the cutter head in use; Figs 4 to 8 show an alternative cutter head and
clamp bar arrangement for the cutting machine of Figs 1
to 3 in accordance with an embodiment of the invention; Fig 4 shows a section through the cutter head and
clamp bar generally similar to that of Fig 2; Fig 4A shows a portion of Fig 4 on a larger scale; Fig 5 shows further details of Fig 4, but the
section being taken with an opposite viewing direction and
showing the fasteners employed for mounting the bearing
elements on the cutter head; Fig 6 shows, on a larger scale and in perspective,
one of the bearing elements of Figs 4 and 5; Figs 7 and 8 show elevation views of the cutter head
of Fig 5 from the front and rear, as indicted by arrows
VII and VIII in Fig 5, and showing the positional
locations of the mounting and adjustment fasteners for the
bearing elements.
PRIOR ART
AS shown in Fig 1 of the drawings, a machine 10 for
cutting card, board and like materials as used by picture
framers, artists, designers, photographers etc comprises
a base board 12 to support the card, board and the like
to be cut. A clamp bar 14 extends upon the base board to
clamp materials to be cut. Mounting means is provided for
the clamp bar and comprises a pair of spaced arms 16, 18
between which the clamp bar is connected. Means is
provided for raising and lowering the clamp bar to allow
insertion of the materials to be cut. This means permits
at least the ends of the arms 16, 18 to be raised and
provides a torsion bar 20 interconnecting the ends of the
arms 16, 18 for manual lifting by the user, and a pair of
support legs not seen in the drawings, whereby the bar 20
can be held in a raised position for inserting of card
under the clamp bar. The arms of 16, 18 comprise leaf
springs 22, 24 which permit the tension bar 20 to be
raised by simple bending of the springs. This provides
a very durable construction. A cutter head 26 is mounted
on clamp bar 14 for lengthwise sliding movement with
respect thereto, to cut the card or other materials. Stop
means, not shown in detail, is provided for a user
accurately to cut card to size and to cut apertures, for
example aperture 28 shown in card 30, during use.
Fig 3 shows cutter head 26 in use, with the hand 32
of the user actuating, by means of thumb and index finger
a pivotal cutter element 34 having a blade 36, pivotal
movement of an axe is generally at right angles to the
surface 38 as seen in Fig 2 enables the user to bring head
36 in and out of its cutting position.
Turning now to Fig 2, it will be seen that clamp bar
14 is shown together with a sliding block 40 forming part
of cutter head 26. Block 40 provides a mount forming part
of element 34 carrying blade 36. Blade 36 engages the
material to e cut by projecting slightly beyond the edge
42 of clamp bar 14. Blade 36 and cutter element 34 are
not shown in Fig 2. Clamp bar 14 is formed with recesses
44 and 46 to mount scales for measurement purposes during
use. Profiled recesses 48, 50 and 52 in sliding block 40
provide mounting for further structures of the cutting
machine not relevant for purposes.
As shown in Fig 2, cutter head 26 is located on
clamp bar 14 by means of a sliding locater 54 mounted on
block 40 by means of a fastener 56 and an intermediate
spring element 58. Locater 54 is generally of upwardly
tapering form and is received in a corresponding channel
56 formed in clamp bar 14. Fastener 56 is adjusted so
that the locater freely slides in channel 56.
In order to support cutter head 26 for free sliding
movement lengthwise of clamp bar 14, there is provided co-operating
guide means on the clamp bar and on the cutter
head, the guide means on the clamp bar and on the cutter
head comprising a lengthwise extending guideway on the
clamp bar and a guide member on the cutter head, the
guideway and the guide member having complementary
tapering profiles. As shown in Fig 2, guideway 60 is in
the form of a wedge shaped slot formed in clamp bar 14,
and guide member 62 is in the form of a projecting wedge
member received in the slot. These cooperating guide
elements provide sliding location of the cutter head 26
relative to the clamp bar.
In addition to the guideway 60 and guide member 62
there are also provided interengaging sliding support
surfaces 64, 66 which serve also to resist downwardly
directed loads in use.
Before use, the locater 54 is adjusted to provide
sliding movement while adequately locating cutter head 26.
After that no further adjustment is needed. Surfaces 64,
66 and the engaging surfaces of the guideway and guide
member 60 and 62 are provided with a low friction material
such as UHMW Polyfine to promote free sliding movement.
SLIDEWAY BEARINGS
Turning now to the embodiment of the present
invention, this is shown in Figs 4 onwards and will now
be described on the basis of representing a modification
of the prior art system described above in relation to
figs 1 to 3. Such modification involves the use of a
modified clamp bar and a modified cutter head. In this
embodiment of the invention, reference numerals will
commence at 100.
Therefore, as shown in Fig 4, machine 100 for
cutting card, board and like materials comprises a clamp
bar 102 having a cutter head 104 mounted thereon and
corresponding to cutter head 26. Details of the
construction of cutter head 104 from cutter head 26 differ
in respects which are unimportant for the purpose of the
present invention and will therefore not be described.
The important differences of the present embodiment from
cutter lead 26 relate to the systems provided for location
and for lengthwise sliding movement and lateral guidance
and for the provision of means to slidingly resist
vertical and related loads.
In the system on Figs 1 to 3, cutter head 26 is
located with respect to clamp bar 14 by sliding locater
54 mounted on block 40. Lateral guidance is provided by
complementary tapering profiles provided on guideway 60
in the form of a wedge shaped slot, and a corresponding
guide member 62 in the form of a projecting wedge member
received in the slot. Bearing surfaces 64 and 66
slidingly support the cutter head.
In the present embodiment, the entire system for
providing not only location but also lateral guidance and
bearing support against downward loads during use, is
provided by a guideway 106 on clamp bar 102 and
cooperating bearing elements 108, 110 provided on cutter
head 104.
As shown in Fig 4, guideway 106 has outwardly facing
and upwardly-diverging guideway surfaces 112. Bearing
elements 108, 110 have respective complementary, inwardly-facing
and upwardly-diverging bearing surfaces indicated
in Fig 5 and 114 and 116 but which are more fully
described below with reference to Fig 6.
Bearing elements 108, 110 are received in
correspondingly-rectangularly profiled recesses formed in
cutter head 104 so that their bearing surfaces 114 and 116
are placed for sliding engagement with the corresponding
bearing surfaces 112 of clamp bar 102. The bearing
elements are secured in position by fasteners 118 having
heads 120 received in countersunk apertures 122.
Fasteners 118 have threaded shanks 134 which screw-threadily
cooperate with threaded bores provided at the
inner portion of apertures 122.
Bearing elements 118, 110 extend lengthwise the full
lengthwise extent cutter head of 104 and likewise the
recesses in which they are mounted. These recesses are
provided at the inner side faces of a generally channel-shaped
portion 126 of the cutter head defined by flanges
128 provided on the cutter head.
Fig 4A shows on a larger scale a detail of the
construction of the guideway 106 which can also be seen
in Fig 104, notably the provision of the relieved portions
112A in bearing surfaces 112 to accommodate a degree of
mismatch of the tapered profile arising from, for example,
tolerances introduced during manfacture by extrusion of
the guideway. The relieved portions extend across only
a portion of the width of the relevant bearing surfaces,
such portions being less than half of that width and
indeed slightly less than one quarter thereof. The
relieved portions permit the toleration of more mismatch
than otherwise would be the case without an unacceptable
loss of bearing surface area.
Turning now to the details shown in Fig 6 concerning
the bearing elements 108,110 we mention first that the
bearing element material itself may be chosen according
to the specific characteristics required and according to
the predispositions of the user. A typical example might
be a UHM (Ultra high molecular weight) Polyolefin, or PTFE
or a derivative thereof or any other polymer having
suitable friction and wear characterises whether with or
without a filler or other materials.
As shown in Fig 6, the inner bearing face of each
of the bearing elements 108, 110 has a central relieved
portion 132 which is relieved to the extent of a few
millimetres in depth in order to ensure that the end
bearing regions 134 provide the entire inclined and
inwardly facing bearing surfaces for the bearing element.
Each of the bearing elements is similarly constructed in
this regard. Fig 6 does not show the generally wedge-shaped
profile of the bearing element very clearly. This
can be readily seen in Figs 4 and 5.
Apertures 122 are formed in the central relieved
region 132. Thus, the bearing elements are mounted and
supported in their central region and their bearing
regions are capable of being deflected for bearing
adjustment reasons as explained below.
In this latter, regard as show in Fig 7, cutter
head 104 is provided with additional screw threaded
apertures 136 to receive corresponding threaded fasteners
138 for adjustment purposes. The adjusters 138 have
suitable driving formations such as slots or sockets
whereby there can be threaded inwards or outwards for
engagement of their inner ends (not shown) with the rear
side of end bearing regions 134 of bearing elements 108,
110 so as to adjust these towards and away from the
corresponding tapering services 122 on guideway 106.
Provisions for such adjustment is only made at one side
of cutter head 104 namely with bearing element 108, since
this is sufficient to make all required adjustments.
Other details of cutter head 104 seen in Figs 4 to
8 are not described since they do not concern the present
invention.
In use, after installation of the cutter head, the
clearances of bearing element 118,110 are adjusted by
means of fasteners 138 in order to provide free running
but backlash-free guided sliding movement of the cutter
head.
STOPGAUGE CALIBRATION
Turning now to the embodiment of Figs 9, 10 and 11 -
13, there is shown an end stop device in the form of a
start-of-cut assembly suitable for use with a cutting
machine of the kind shown in Fig 1 of the drawings. Such
an assembly defines the location at which the cutter head
is caused to stop in its lengthwise travel along the
guideway at that end of its travel which represents the
start of cut. The assembly is slidably mounted on the
clamp bar 14, (see Fig 1). Although not shown in fig 1,
the assembly would be mounted at a location to the right
of cutter head 26 in Fig 1 so that the cutting travel of
the cutter head extends from the stop assembly in a
leftwards and downwards direction, as seen in Fig 1,
towards the other stop which is indicated at 200.
Stop assembly 202 of Figs 9 to 13 incorporates a
calibration device 204 which may also be used in the other
stop 200, and likewise in other adjustable measurement
devices on the cutting machine 10 including the so-called
mat guide 206 (with sliding adjusters 208,210) and the
limit stop 212 for presetting mat sizes.
Broadly speaking, the calibration device 202 is
applicable to the several identified locations in cutting
machine 10 at which the position of a stop device or like
mechanical element depends for the accuracy of its setting
on user-perceived mechanical setting data on a main
setting scale, the interpretation of which will vary, to
some extent from one user to another. Accordingly, by
provision of a resettable calibration device the
calibration setting which any particular user finds
convenient and which leads to accurate cutting can be
readily achieved and returned-to in accordance with the
features to be described below.
As shown in Figs 9 to 13, calibration device 204
comprises a stop member in the form of an arm 214
projecting laterally from a slidable caliper 216 received
on a lengthwise extending scale 218 carried on clamp bar
14 (not shown in Figs 9 to 13). An indicator 220 mounted
on caliper 216 co-operates with measurement scale 218 to
indicate the adjusted position of caliper 216. A setting
knob 222 having a screw-threaded shank 224 co-operates
with scale 218 and caliper 216 to fix the caliper in a
selected adjusted position.
Arm 214 has a leaf-spring-mounted extension 226
having a projecting contact 228 to rest on the upper
surface of the sheet material being cut.
Calibration device 204 further comprises manual
adjustment means 230 adapted to adjust the relative
positions of indicator 220 and measurement scale 218 to
permit selective compensation or offset for detecting
errors in the resultant cut dimension produced by the
cutting machine. Calibration indication means 232 is
provided to indicate the extent of calibration selected
from a pre-determined nominally zero position.
Calibration indication means 232 comprises a calibration
scale 234 and an associated indicator 236.
As can be clearly seen in Figs 12 and 13,
calibration scale 234 and indicators 220 for measurement
scale 218 are formed as a one-piece generally U-shaped
structure having corresponding twin limbs which is
slidably received in corresponding grooves seen best in
Fig 10 whereby it is lengthwise-adjustable at a location
above measurement scale 218 and in a direction generally
parallel thereto. An adjustment knob 238 having a
corresponding screw-threaded shank 240 on which is
received a coiled compression spring 242 serves to provide
an adjustment function for indicator 220 and calibration
scale 234. Indicia 244 and an associated adjustment
direction arrow 246 serve no identify the direction of
rotation of knob 238 for positive or negative calibration
adjustment from a nominal zero position seen in Fig 9.
It can now be readily understood that adjustment of
the calibration device 204 by means of adjustment knob 238
effects simultaneous adjustment both of indicator 220 and
of the calibration scale 234, since these are a one-piece
construction which is slidingly mounted on caliper 216.
As scale 234 is moved in the negative direction (towards
the bottom of the page in Fig 9) so the calibration scale
234 is likewise moved simultaneously downwards so that
indicators 236 then indicate a setting in the upper (and
negative) portion of scale 234. Any chosen setting is
readily retained by the frictional effect of spring 242
on the threaded shank 240 of adjustment knob 238.
In use, if it is found that a given cut is
unacceptable in terms of length at the start of cutting,
then the appropriate plus or minus adjustment is made by
means of calibration adjustment knob 238 followed by
setting knob 222 - which latter enables the actual stop
itself then to be correctly positioned.
It will be understood that this aspect of the
present invention is not limited to use in relation to
devices involving a cut-limiting stop but may, for
example, be used for calibration of the setting scale for
other dimensional aspects of the cutting procedure
including the positioning of board or other materials to
be cut with reference to the apparatus as such.