Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to the surface preparation of
solid materials to improve their interaction with other
materials. Such interaction may include adhesive and/or
mechanical bonding, heat exchange, catalysis or frictional
engagement.
REVIEW OF THE ART
It has long been known to roughen, abrade,
mechanically indent or otherwise modify or mechanically
deform the surface of materials to improve their
interaction with other materials in a wide range of
applications. For example such preparation usually
improves the bonding of the prepared material to other
materials such as adhesives used to adhere the surface to
a surface of another material, or to materials directly
bonded to the surface of the first material, as by casting,
fusion bonding, and coating, plating or other forms of
deposition. Such preparation may also be used to improve
contact between the surface and a fluid, as for heat
exchange purposes, or to raise its coefficient of
frictional engagement with other surfaces, for example to
reduce slippage. Such surface preparation techniques
operate by increasing the surface area of the material,
providing contact surfaces in many different planes rather
than a single plane so as to provide improved keying and
ensuring that a fresh surface of the material is exposed
for interaction.
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Most surface preparation techniques involve only a
surface plane of the material having very limited
thickness, and while such techniques are often very useful
and effective, they necessarily involve a correspondingly
thin layer of the material with which interaction can take
place. Such techniques are not usually very effective in
providing improved interaction with fluids, since the
irregularities in the surface occur largely in a more or
less static boundary layer of the fluid. While techniques
involving extensive penetration and deformation of the
material have been proposed or utilized, they involve a
correspondingly substantial thickness of the material being
treated, which entails that the material must be in a layer
of much greater thickness if substantial weakening of the
material is to be avoided. This difficulty is well
illustrated by the arrangement shown in U.S. Patent No.
3,746,086 (Pasternak) in which the walls of heat exchanger
tubes are provided with increased surface area by a series
of deep diagonal cuts forming fir-cone like vanes on the
tube. To accommodate these cuts, the material of the tubes
is formed with massive external ribs to provide material
for the vanes without prejudicing the integrity of the tube
walls. Likewise, the bonding technique of U.S. Patent No.
4,349,954, in which the surface of a material is formed
into a forest of cones, is clearly feasible only with
workpieces of much greater thickness than the depth of the
cones formed on the workpiece surface.
In general, none of the techniques considered above
provide, in bonding applications, for any form of positive
interlocking or interengagement between the material whose
surface is treated and a material with which the treated
surface interacts.
Another well known form of surface treatment of
material is planing, in which a planing tool is utilized to
plane shavings from the surface of the material so as to
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flatten it or reduce it to a desired contour. One known
form of planing tool is the "speed file", as exemplified by
Canadian Patent No. 927,081, which has multiple small
spaced apart planing blades which conjointly cut a number
S of spaced shavings from the surface of a material being
planed. The multiple blades, and the application of
multiple strokes, result in overlapping of the planing cuts
producing an overall planing of the material and providing
a smooth surface.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a
technique for preparation of a surface of a material to
provide it with improved interaction and positive
interengagement with an interacting material, within a zone
whose thickness can be very large compared to the extent of
surface penetration of the material required by the
technique. The technique is applicable to readily
machinable material, which is defined in the context of the
present invention as a material from which a cutting blade
may plane or gouge a continuous cutting or shaving which
can be smoothly curled out of the cutting plane without
fracture. It is generally associated with substantial
ductility of the material. It will be understood that some
materials which are not readily machinable at ambient
temperatures may be rendered ductile by the application of
suitably elevated temperatures.
The invention in one aspect provides a method of
modifying a workpiece of presenting freely machinable
material at a generally planar surface thereof, comprising
planing without detachment a plurality of curved, elongated
and at least partially retroverted cuttings from spaced,
non-overlapping, elongated troughs of approximately
constant distribution over said surface, the cuttings
remaining continuous with the planar surface at one end of
each trough, using at least one tool providing a planing
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action with a stroke which is small compared with the
dimensions of the surface to be treated, whereby to provide
the workpiece with a modified surface of increased surface
area, part of which increased area is provided by surfaces
of the cuttings which face towards and are spaced away from
a remainder of the workpiece.
Preferably the distal ends of the cuttings are
retroverted through more than 180 so as to present a
series of hooks or loops. The invention also extends to
material having a surface so treated.
It will be appreciated that penetration of the troughs
cut into the surface of the material will be limited by the
planing action of the tool, but the length of the cuttings
is limited only by the requirement that the zones from
which they are planed do not overlap, while their
protuberance from the surface will depend on their
curvature, which is a function of the tool design, but will
normally be very much greater than the planing depth. The
retroversion of the cuttings, as well as continuity of the
roots of the cuttings with the surface, provide zones in
which the modified surface can positively interengage with
another material.
The invention further extends to apparatus for
implementing the method and forming the modified workpieces
of the invention. The apparatus must perform limited
planing strokes distributed over a workpiece surface to be
treated, and provide for disengagement of the cutting edges
from the workpiece at the end of the planing strokes so as
not to separate the cuttings formed from the workpiece. In
general terms the apparatus comprises at least one chisel
member presenting a cutting edge at a planing angle to said
surface, structure providing a gauging surface set back
from said cutting edge and controlling depth of penetration
of the cutting edge into the workpiece during planing
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movement of the cutting of each chisel member relative to
the workpiece, structure providing a guide surface
directing a cutting planed from the surface of the
workpiece by the chisel member into a retroverting curve,
mechanism operable to repeatedly relatively displace each
chisel member and the workpiece through a predetermined
planing stroke whereby to plane a non-detached cutting of
predetermined length from a trough in the surface, and
operable to withdraw the chisel member from planing
engagement with the workpiece, and means for permitting
movement of the workpiece relative to the chisel member so
that a following planing stroke may be performed on a
further zone of the surface spaced from the first zone.
Actual implementation of such apparatus may take
various forms as described further below.
SHORT DESCRIPTION OF THE DRAWINGS
In the drawings:
Figure 1 illustrates a fragment of a workpiece showing
a single cutting planed from a trough in a surface of the
workpiece;
Figure 2 illustrates a workpiece from which have been
planed a plurality of cuttings similar to that of Figure 1;
Figures 3, 4 and 5 are fragmentary views similar to
Figure 1, showing progressive stages in the formation of a
cutting;
Figure 6 is a further fragmentary view showing how
cuttings may be pressed back into their associated trough
to trap fibres;
Figure 7 is a cross-sectional view showing how two
workpieces may be pressed together to interlock cuttings
formed on opposed surfaces of the two workpieces;
Figure 8 illustrates a type of interengagement
possible when the cuttings are longer and thinner;
Figure 9 illustrates basic features of a tool for
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carrying out surface preparation in accordance with the
invention;
Figure 10 shows the tool of Figure 9 at a later stage
of engagement with a workpiece;
Figure 11 diagrammatically illustrates elements of a
first form of apparatus for surface treating workpieces;
Figure 12 illustrates a different phase of operation
of the apparatus of Figure 11;
Figure 13 illustrates a means for controlling depth of
penetration of planing blades in the apparatus of Figure
11;
Figure 14 is an edge elevation of a workpiece treated
with the apparatus of Figure 11, and bonded to a further
layer of material;
Figure 15 shows a blade used in a modification of the
apparatus of Figure 11;
Figure 16 shows an assembly of two blades as shown in
Figure 15, but arranged to cut in opposite directions;
Figure 17 illustrates the assembly of Figure 16 in
cutting engagement with a workpiece, illustrating the
cutting forces applied thereto;
Figures 18, 19 and 20 are plan and end and side
elevational views showing means for registering multiple
blades and reciprocating them to perform a planing stroke;
Figure 21 shows in elevation a further embodiment of
apparatus for surface preparation of workpieces;
Figure 22 is a detail on an enlarged scale of the
apparatus shown in Figure 21;
Figure 23 is a plan view of the apparatus of Figure
21;
Figure 24 is an isometric diagrammatic view of a
further embodiment of apparatus;
Figures 25 and 26 show sets of blades used in yet a
further embodiment;
Figure 27 is a plan view of the blades; and
Figures 28 and 29 are enlarged views of a single blade
at different stages of its stroke.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figures 1 and 2, a surface prepared in
accordance with the invention presents a plurality of
spaced, curved tongues 16 formed by cuttings planed out of
the surface 12 of the material 10 (which must obviously be
sufficiently freely machinable, at least at its surface,
for this to be possible). By freely machinable in this
context is meant that it is possible to plane from a
surface layer of the material and deflect away from the
surface a continuous "chip" or coherent curved cutting of
the material. The term "cutting" is preferred in the
present context rather than "chip" or "shaving" or other
terminology used in the machining art, to avoid any
implication that the cutting is detached from the surface,
or has a particular cross-section, or is formed from the
surface by a mechanism other than planing. Some materials,
such as certain plastics, may not be freely machinable at
ambient temperatures but become so when the workpiece
and/or the cutting tool is at an appropriately elevated
temperature, and such materials so heated during surface
preparation are within the scope of the invention.
Materials such as ductile metals and synthetic plastics are
examples of materials suitable for application of the
invention. It should also be appreciated that it is only
the characteristics of the material presented in a surface
layer of the workpiece which are significant in relation to
the invention.
The term "planing" is utilized to describe the action
utilized in preparing surfaces in accordance with the
invention, in which a cutting tool is driven into the
surface of a workpiece to a controlled depth and thus
advanced in a direction generally parallel to the surface
of the workpiece to plane or gouge from it a cutting which
is deflected away from the surface but remaining attached
to the workpiece adjacent the cutting edge. This leaves a-
trough in the workpiece which is of substantial uniform
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cross-section except for an initial portion where the tool
enters the workpiece material. Unlike in normal planing or
shaping, the tool is not advanced to a point at which the
cutting tool severs the cutting from the surface: instead,
the strokes of the cutting tool are short enough that they
affect non-overlapping portions of the workpiece surface,
and are short compared to the dimensions of the surface to
be treated, and at the end of a stroke, the relative
movement of the tool and the workpiece is reversed to
permit the tool to disengage from the workpiece in a manner
which avoids detaching the cutting. This is in contrast to
regular planing and shaping processes, in which such
disengagement is to be avoided, and in contrast to
broaching procedures, in which overlapping cuts of
progressively increasing depth are required.
It will be noted by reference to Figure 2 and the
enlarged fragmentary view in Figure 1 that the tongues 16
are planed or gouged out of the surface 12 from a trough 14
which initially increases in depth as the forming tool 24
(see figures 9 and 10) penetrates the surface to a depth 5
during translational movement as shown by the arrows and
then continues at a substantially constant depth as the
translational movement of a cutting edge 4 continues, the
resulting cutting being deflected in a curved path up the
surface 2 so as to form a tongue 16. As shown in Figures
3, 4 and S, the degree of retroversion of the tongue
increases as the length of the cutting stroke increases,
and may be selected to suit the application. Tongues 16a
and 16b directed in opposite directions may be provided.
Figure 6 illustrates how fibres 18 from a sheet of
fibrous material, which may form reinforcement for a layer
of resin, may be physically bonded to the surface of the
workpiece by applying pressure to the workpiece to flatten
the tongues 16 partially back into the troughs 14 and thus
trap the fibres 18: the tongues are thus keyed both in the
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resin and its reinforcement, providing a superior bond.
Figure 7 illustrates how tongues formed on two
similarly prepared workpieces may be interengaged and the
workpieces then pressed together to flatten and further
interengage the tongues, thus physically locking the layers
together and complementing the action of a layer of
adhesive 19. Figure 8 shows a similar technique, except
that the tongues are much longer and thinner, forming curly
fibres 22. The fibres from the two workpieces intertwine
and interlock somewhat in the manner characteristic of
hooked pile fabrics such as those sold under the trademark
VELCR0. The fibres 22 can of course form reinforcement for
a resin layer 23, as well as bonding it to the workpieces.
A prepared workpiece 10 may also be bonded to a
further layer 25 of material (see Figure 14) by causing the
material to surround the tongues 16 and fill the troughs
14. This may be achieved in various ways, for example, a
layer of setting resin, metal or other material may be
cast, plated or otherwise deposited or coated onto the
workpiece 10, and caused to cure or set, or material may be
deposited in powder form and subsequently fused, or a layer
of fusible material may be pressed onto a heated workpiece
10 to cause local fusion of the material so that it flows
around the tongues 16 and into the cuts 14. In one
application, the workpiece may form a battery plate, and
active electrode material may be bonded to the surface.
It will be noted that an effect of the retroversion of
the cuttings that produce the tongues 16 is that, as well
as increasing the surface area of the workpiece, the
cuttings present surfaces that face back towards the
workpiece and thus provide positive engagement with a
material with which the treated surface interacts.
It will also be noted that the protrusion of the
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tongues 16 formed by the cuttings is large compared with
the depth of the troughs 14. This has the dual benefits
that substantial protuberances from the surface may be
produced without involving more than a surface layer of the
workpiece, and that the protuberances can be extensive
enough to penetrate through a boundary layer of a material
with which the treated workpiece interacts. This is
valuable not only in increasing the strength of bonds of
various types already considered, but also when the
interacting material is a moving fluid, whether a gas or a
liquid, for heat exchange or catalysis purposes, since the
tongues will extend through a relatively static boundary
layer to interact with the moving fluid, and the
retroverted tongues will induce turbulence in the fluid
adjacent the treated surface. As well as the mechanical
treatment already considered, this treatment may include
the application of a layer 15 (see Figure 1) of catalyst to
the tongues. The tongues may also be either left as is, or
compressed, in order to provide increased frictional
interaction with solid bodies, i.e. a non-slip surface.
A simple planing tool as shown in Figures 9 and 10 may
be utilized to apply the surface treatment discussed above
in that the block 24 provides a hand grip by means of which
the tool may be moved in the direction of the arrow to
apply a planing stroke and withdrawn in the opposite
direction to disengage the tool from the cutting. The
bottom surface of the block 24 provides a gauging surface
which limits the penetration of the blade 4 into the
surface, and the surface 2 curves and retroverts the
cutting. The hand grip permits the tool to be moved to
different parts of the surface to provide a series of non-
overlapping cuts, which may be reversed in direction to
provide cuts in the opposite direction.
In most commercial applications, a less labour
intensive technique is required. The apparatus shown in
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.
Figures 11-13 may be utilized to prepare workpieces 10 as
shown in Figure 14. The apparatus comprises a set
alternating complementary cutting blades 31 and 32, each
with multiple cutting edges 4, the edges being directed in
opposite directions on the tools 31 and 32 respectively.
Each edge 4 is associated with a surface 2 for curling the
cutting 16 it produces, and each blade is formed with a
bell-curved notch 8 in its upper surface, slightly offset
from its centre. The blades 31 and 32 may be identical,
their designation depending upon the direction in which
their edges face. Although the blades resemble broaching
tools, they differ in that there is no progression in the
depth of cut of the multiple cutting edges 4. The set of
blades 31 and 32 is subjected to bias pressure on its ends
to tending to force the blades into alignment as shown in
Figure 1. A cylindrical actuator 3 is reciprocated between
the position shown in Figure 11 and the position shown in
Figure 12, forcing the blades downwardly and outwardly as
shown by arrows 6 and 7 to provide a plurality of planing
cuts in a workpiece as shown in Figure 14 (ignoring the
layer 25). Plates 9 (see Figure 13) on the outsides of the
set of blades provide gauging surfaces 11 which limit the
penetration 5 of the cutting edges 4 into the workpiece.
A modified cutting tool 31 is shown in Figure 5 in
which the gauging surfaces 11 are incorporated into the
tool. The action of this modified tool in relation to a
workpiece 10 is illustrated in Figures 6 and 7, while
further details of means to bias the tools and actuate the
tools are to be seen in the apparatus illustrated in
Figures 18-20. The tools 31 and 32 are vertically aligned
by pins 18 passing through horizontal slots 17 in the ends
of the tools, which may be spaced if desired by shims 13.
The bias on the tools is provided by tension springs 19
acting on extensions 18a of the pins 18 so as to cause the
latter to act on inner ends of the slots 17. The actuator
3 extends between plates 40 supporting an anvil 41 which
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may be struck to force the pin 3 into the bell shaped
recesses 8 and thus actuate the tools to provide a series
of cuts in spaced non-overlapping zones over a surface of
the workpiece 10. Means (for example similar to the ports
64 and 66 in Figure 21) may be provided to advance a
continuous workpiece laterally or longitudinally relative
to the apparatus between each blow on the anvil 40 so that
successive portions of the surface may be treated.
Referring now to Figures 21-23, apparatus suitable for
processing of the surface of a continuous sheet is
illustrated. Cutting blades 4 and associated retroverting
surfaces are formed on links 50 of a series of parallel
chains 52 supported on sprocket sets or rollers 54, 56, 58,
60 and 62. Material whose surface is to be treated is
advanced across a support 64 beneath the sprocket set 60 by
rollers 66 which are geared to the sprocket 62 such that
the material 10 is advanced by them at a rate substantially
greater than the rate at which the chain 52 pass beneath
the sprocket set 60. As each tooth 4 passes beneath the
sprocket set 60, it enters the surface of the workpiece 10
to an extent gauged by the position of the support 64
relative to the sprocket set 60. Since the tooth 4 faces
away from the direction of advance of the chain and the
workpiece, and the workpiece is travelling faster than the
chain, the tooth performs a planing stroke relative to the
workpiece so as to penetrate the latter, cut a cutting from
it and then withdraw from the cut as best understood from
Figure 2. Although the cutting strokes of the teeth are
not strictly linear, the trough produced will still be of
sufficiently uniform depth to meet the requirements of the
invention provided that the diameter of the sprocket set 60
is very large compared to the depth of cut. In a variation
of this embodiment shown in Figure 24, the teeth 4 are
formed directly on a set of disks 70 replacing the
combination of the sprocket set 60 and the chains 52. In
a further variation the chains 52, or the periphery of the
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set of disks in the modified embodiment of Figure 24, are
driven so as to advance faster than the workpiece, but are
braked to a standstill for a predetermined period each time
a tooth engages the workpiece so as to cut a trough of
predetermined length. In the embodiment of Figures 21-23,
the braking may be applied to sprocket set 62.
In the embodiment of Figure 24, similar reference
numerals are utilized where applicable, but the chains 52
and associated sprockets are replaced by the disks 70. In
the example shown, these are mounted on a square section
shaft 72, inserted through square central apertures 78 in
the disks, the shaft being advanced intermittently in the
direction of the arrow 74 at a rate greater than the
workpiece is moved in the direction 76 so as to bring a
tooth 4 into engagement with the workpiece, at which point
the shaft is halted so that the workpiece is moved past the
blade as shown and cuts a cutting 16 from a trough 14.
After a period sufficient for a trough of the desired
length to be cut, the shaft is indexed to engage the next
blade with the workpiece. Either the back of the teeth are
sharpened to aid penetration, or sufficient resilience is
provided in the mechanism to allow a tooth to be advanced
to the starting point of a cut.
A further embodiment of apparatus is shown in Figures
25-29. This embodiment utilizes rows of rotatable cutter
members 90 of generally volute form, the cutter members in
each row being mounted on a carrier 88 in a common plane on
pivots 92 with their axes horizontally spaced. Typically
the axes of members in adjacent parallel rows will be
offset, as shown in plan in Figure 27. Members in a row
have crank pins 94 connected by a coupling rod 96, the
positioning of the crank pins on the members in different
rows being such (see Figures 25 and 26) that motion of the
connecting rods in the same direction B will rotate the
sets members in opposite directions A to cause cutting
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blades 4 on the members to plane cuttings from a workpiece
10 (see Figure 28). While movement of the rods in the
opposite direction will withdraw the blades 4 from the
workpiece (see Figure 29). The volute form of the
periphery cutter members forms a gauging function
controlling the depth of cut. The workpiece 10 to be
surface treated is indexed by a feed mechanism (not shown)
in the direction C (see Figure 27) between each
reciprocation of the coupling rods 96 which may be driven
from a crankshaft (not shown) by connecting rods (not
shown).
It will be appreciated that the examples of
applications and manufacturing apparatus outlined above are
exemplary only and modifications and variations thereof are
within the scope of the invention as defined by the
appended claims.
