Note: Descriptions are shown in the official language in which they were submitted.
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SPECIF~CATION
In a surface modification process to prepare certain materials e.g. metals,
for bonding it iS common to employ some form of mechanical preparation
e.g. abrasive blasting, to 'key' the surface allowing for increasing adhesion
5 (a combination of physical interactions and chemical reactions) of the
adherend (the material being joined) and the adhesive . However the
surface so prepared is highly random when viewed in microscopic detail,
with each differently sized and oriented abrasive particle being blasted at
the material's surface, leaving a different imprint or pit none of which are
10 necessarily the optimum shape for maximizing adhesive bonding. Thus the
surface is roughened and pitted but not in an engineered or optimum
manner. Furthermore said process will allow for air entrapment under the
adhesive which in turn prevents perfect 'wetting' or contact between the
adhesive and the depths of the air-entrapping pits. Other preparation
5 involves the use of wire brushing to roughen the surface but for much the
same reasons the abherends (the two materials being joined) are not
optimized for the bonding process. Grinding and machining also leave a
very roughened surface but random in detail, not the optimum surface.
Furthermore none of these processes address the clamping requirement in
20 adhesive bonding where often relatively long periods of clamping time are
required for the adhesive to fully cure. Clamping prevents relative
movement of the pieces. Moreover these processes do not allow for surface
embedment of the keyed surface of a hard, stiff material, e.g. metal, so
modified, into another lower melting point material, e.g. a plastic.
25 Furthermore these processes do not allow an effective means of effectively
engaging an added fibrous material which may be desirable in said
bonding.
I have found these limitations can be overcome by using the process
disclosed herein which I call "BondFace" which provides a means of
30 modifying by 'keying' the surface of many materials through the use of a
tool to 'cut' or 'plow'- a 'path', 'groove', 'channel' or 'furrow' into the
surface simultaneously displacing the material's surface creating a 'burr' or
'barb' useful as a 'key' or 'grip' for adhesive adhesion to said materials.
The formed burr is not severed from said material. The process thus raises
35 a 'burr' or 'non-severed chip' e.g. "a rough or sharp edge left by a cutting
tool" in the material's surface where the tool was applied, to provide a
'grip' or 'key' for adhesive bonding. By this means a material's surface can
be modified to comprise multiple burrs, creating a keyed surface, by the
repeated application of the tool to the material. The tool's cutting edge used
40 to create said keying burrs can be designed to provide a burr of specific
shape, size and cross section allowing surface keying for specific
requirements. The advantage of this process is that keyed surfaces can be
created with burrs formed in the abherends, in the size, quantity and
location required. Moreover the burrs produced may be formed to a hook
45 shaped key to allow engagement with other suitable materials, e.g. fabrics.
Assembly pressure applied to keyed surfaces will cause burrs to crush
about one another forming a keyed interface matrix of integrally formed
fiber-like reinforcement for the adhesive with self-clamping of the pieces.
This will then allow the bonding and clamping operations to be
so substantially combined lowering costs and increasing joint strength and thus
leading to cheaper end-products of increased integrity. Other media, e.g.
inorganic fibers, can be easily incorporated into said key-burred surfaces
where adhesive and fiber captured by reclosing the burrs using sufficient
assembly force, also produce improved joint strength and end-product
ss integrity. Large areas of material can be keyed using a tool designed with
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multiple cutting edges to simultaneously create multiple burrs- there being
no reasonable upper limit. Moreover this process allows for another unique
type of bonding between two different base materials, e.g. a metal and a
plastic, where the 'keyed by burring' metal is heated to a sufficient
5 temperature to cause each burr to melt it's way into said plastic which will
'flow' about the burr and then solidify upon cooling -entrapping and
embedding each burr so keying the pieces together.. By this manner
materials can be joined even where no suitable adhesive exists.
Furthermore the tool may be operated when heated to a temperature
o sufficient to allow key-burring of normally brittle material, e.g. certain
plastics.. An added feature of the process allows that the burrs can be
formed in a random pattern or in a highly regular pattern. The regular
pattern would allow a high percentage of engagement of opposing burrs on
two surfaces when said surfaces are pressed together. However when the
second surface is not involved, e.g. paste metal-filler compound, then the
random pattern will allow a simpler, portable tool to key the surface
In drawings which illustrate embodiments of the invention, Figure 1 shows
an orthographic view of the preferred embodiment of a single burr in thin
sheet material, Figure 2 shows the same embodiment in multiple form,
Figures 3, 4, 5, and 6 show enlarged views of burr where Figure 3
shows a burr in the earliest stage of formation, Figure 4 shows a burr
which has been raised further and Figure 5 shows a burr raised still
further with a hook shape, Figure 6 shows a burr which has been reclosed
entrapping a fiber strand. Figure 7 shows a cross sectional view of two
surfaces whose burrs engage, Figure 8 shows an interface mesh of burrs
keyed together, Figure 9 shows an embodiment of a tool used to create
burrs and Figure 10 shows the same embodiment where ~he tool has
entered the material creating a burr.
The groove 1 cùt in stiff material A produces a burr 2 of the required
shape, size and cross section as defined by the tool's edge design 4 shown
in Figures 9 and 10. This is achieved with a tool apparatus 3 also in
Figures 9 and 10, which has the capacity to cut into A to a specific depth 5
in Figures 9 and 10, creating a 1 and a 2 simultaneously, holding
penetration into the material and therefore the depth of 1 and thickness of
1 to a predeterrnined maximum as defined by 5 in Figures 9 and 10, and
'peeling' back a layer of A. The effect is to pierce and 'peel back' the
surface or skin of the A with 3 where the design and shape of 4, produces
the shape desired for 2. In Figure 2 multiples of 2 are depicted over a
significant portion of the surface of A. Figure 3 is of an enlarged view of
2 to allow further inspection of the detail of 2 and it's relationship to 1
and A, 2 has just begun to be 'peeled back' by 3 (not illustrated). Figure 4
shows what happens to 2 when 3 continues to advance against the now
raised 2. Figure 5 depicts the extreme that 2 can be made to be with a
pronounced 'hook' to allow meshing with fibrous or 'loop-like' material.
Figure 6 depicts 2 reclosed and entrapping a strand of fiber C. Figure 6
shows only A however the entrapping of C between the surfaces of A and
B represents a very powerful feature of this invention. In Figure 7 only
two specifically shaped 2's of the form shown in Figure 3 are shown
engaged but large numbers of 2 would allow substantial strength of
so mechanical fastening between A and B. Figure 8 shows the interface
between A and B where multitudes of 2 are entwined about each other in
the thin space between the surfaces. Figure 9 shows a tool designed to
create a basic 2 where 3 is the tool body with cutting edge 4 and depth-of-
cut limiter ~. To cut a 1 forming a 2 in the surface of A, 3 is moved in
ss the direction shown in 3 by the arrow, against a stationary A the distance
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required to create a 2 of the forms shown in Figures 1,3,4,S and 7.
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