ABRASIVE PRODUCT AND METHOD

PRODUIT ABRASIF ET PROCEDE DE FABRICATION CORRESPONDANT

English Abstract

ABSTRACT OF THE DISCLOSURE
A method of making a flexible abrasive product
comprises bonding a conductive sheet to a flexible
substrate, applying a surface mask to said sheet to
define a multitudinous pattern of holes having a
predetermined shape, and electrodepositing metal onto
said conductive sheet through said holes in the presence
of particulate abrasive material to form metal pellets
carrying said particulate abrasive material. The product
has excellent abrasive properties, good flexibility, and
durability.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE AS FOLLOWS:

1. A method of making a flexible abrasive product
comprising:
a) bonding a conductive sheet to a flexible substrate;

b) applying a surface mask to said sheet to define a
multitudinous pattern of shaped holes: and

c) electrodepositing metal onto said conductive sheet
through said holes in the presence of particulate abrasive
material to form shaped metal pellets carrying said
particulate abrasive material.
2. A method as claimed in claim 1 wherein said holes
form a regular pattern in said mask.

3. A method as claimed in claim 2 wherein said holes
are crescent-shaped.

4. A method as claimed in any of claims 1 to 3 wherein
said conductive sheet is copper foil, said substrate is a
polyaramid fabric resin bonded to said copper foil, said metal is
nickel, and said abrasive particulate material is diamond grit.

5. A method as claimed in any of claims 1 to 3 wherein
said mask is silk-screend onto said conductive sheet.

6. A method as claimed in any of claims 1 to 3 wherein
said mask comprises a photoresist material which is exposed and
developed to define the shaped holes.

7. A method as claimed in any of claims 1 to 3 wherein
said mask and exposed copper foil are removed by etching after
said electrodeposition.



8. A flexible abrasive product comprising a flexible
substrate having a multitude of metal pellets bearing particulate
abrasive material attached thereto, said pellets being arranged
in a pattern and having a predetermined shape.

9. A flexible abrasive product as claimed in claim 8
wherein said pellets are crescent-shaped.

10. A flexible abrasive product as claimed in claim 9
wherein said pellets are arranged in a regular pattern.

11. A flexible abrasive product as claimed in any of
claims 8 to 10 wherein said pellets comprise electrodeposited
metal on copper segments resin-bonded to said substrate.

12. A flexible abrasive product as claimed in any of
claims 8 to 10 wherein the substrate is a polyaramid fabric.

Description

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This invention relates to a m~thod of making a ~lexible
abrasive product.

An abrasive product has been proposed in which abrasive
particles, such a diamond grit, are embedded in nickel pellets
carried on a substrate. Such a product is made by electro-
depositing nickel through holes formed in a mask applied to the
surface of the substrate, which can be a fabric rendered
conductive.

An object of the invention is to improve the technique
for manufacturing such a product.

According to the present invention there is provided a
method of making a flexible abrasive product comprising: a)
bonding a conductive sheet to a flexible substrate; b) applying
a surface mask to said sheet to define a multitudinous pattern of
shaped holes, and c) electrodepositing metal onto said conductive
sheet through said holes in the presence of particulate abrasive
material to form shaped metal pellets carrying said particulate
abrasive material.

The holes are preferably crescent-shaped and arranged
in a regular pattern, with the convex edges of the crescent
facing the intended direction of movement of the abrasive
product.

The flexible substrate preferably comprises a KevlarTM
fabric bonded to a sheet of copper foil by LomodTM resin.

The mask is preferably in the form of a photo-resist
material applied to the copper foil. The holes can be defined
photographically and subsequently exposed upon development of the
photo-resist material.

~ lternatively, the holes can be defined by means of a
silk-screen process.

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The invention also provides a flexible abrasive product
comprising a flexible substrate having a multitude of metal
pellets bearing particulate abrasive material attached thereto,
said pellets being arranged in a pattern and having a
predetermined shape.

The pellets preferably have a crescent-shape.

The invention will now be described in more detail, by
way of example only, with reference to the accompanying drawings,
in which:-
Figure 1 shows a laminated substrate bearing a surface
mask defining a regular pattern of crescent-shaped
holes;
Figure 2a shows a detail of one of the shaped holes;
and
Figure 2b shows a detail of a group of holes.

The laminate 1, shown in figure 1, comprises a KevlarTM
fabric resin bonded to a copper sheet 2 covered with a surface
mask 3 of photo-resist material defining crescent-shaped holes 4
through which electrodeposition occurs. The laminate shown in
Figure 1 is subsequently placed in an electrolytic tank to permit
deposition of nickel in the presence of diamond grit through the
shaped holes 4. This process produces crescent-shaped pellets at
the locations of the holes with diamond grit embedded in the
nickel.

After removal from the tank, the mask and exposed
copper are striped from the KevlarTM to leave a sheet consisting
of a regular pattern of crescent-shaped pellets firmly attached
to the KevlarTM backing. Each pellet consists of an
electrodeposit of nickel bearing the diamond grit carried on a
crescent-shaped segment of copper bonded to the underlying
fabric.

Figure 2a shows in detail the shape of the holes. The
crescent-shapes are defined by overlapping circles of slightly

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different radii. Figure 2b shows how the holes are arranged
in a symmetrical arrangement.

The manufactured sheet is subsequently cut into strips,
which in turn are formed into belts. The use of crescent-
shapes makes the belts unidirectional, in that the convex
edge has to face the direction of movement a of the belt.

The use of crescent-shapes, permits significant savings
in diamond grit without deterioration in the abrasive
properties since the surface area of the pellets is less than
for circular pellets. Furthermore, the removal of a braided
matter is improved.

The holes can have other shapes. For exam~le, honeycomb
shapes provide the belt with greater rigidity.

The spacing and size of the pellets can be varied to
change the properties of the abrasive product. For rough
grinding purposes, the pellets are spaced further apart and
larger diamonds employed. For smooth grinding applications,
the pellets are brought closer together and smaller diamonds
used .

KevlarTM is a particularly useful material for making
abrasive belts. For disks on the other hand, the copper foil
can be bonded onto fiberglass or other semi-rigid material
and the fiberglass then laminated onto a firm backing, for
example a polyester backing.
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EXAMPLE

A sheet of 10 ounce KevlarTM (a trade mark for p-poly-
phenyleneterephthalamide yarn) 24 by 24 fabric was bonded
under heat and pressure with LomodTM (available from General
Electric) resin to a copper sheet having a surface density of
one ounce per square foot. KevlarTM is a polyaramid fabric.
The surface of the copper sheet was cleaned and scrubbed with
an abrasive brush in a scrubbing machine.




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The cleaned laminate was passed through a dry film
laminator made by Thio~ol/Dynachem Company (Model 30) to apply a
Riston (a trade mark of DuPont) photo-resist film (an alternative
is Dynachem film).

Laminate with the applied photo-resist film was placed
in a Scannex II exposure unit with a template defining the
desired pattern. This template can be produced photographically.

After exposure to ultra violet light, the image was
developed and the protective Mylar film, applied by the
laminator, removed. The laminate was then plated in a plating
bath as described, for example, in our co-pending application
Serial No. 518,201 filed on September 15, 1986.

The plating took place in the presence of diamond grit,
although other abrasives particulate material can be employed, to
form crescent-shaped diamond grit embedded nickel pellets.

After plating, the dry film and exposed copper were
removed with an alkyline stripping and etching solution.

The product was then roller coated with polyurethane
protective resin, having the trade designation UR 2139X-l and UR
2139X-lA by Elecbro Inc.

The sheet was then cut into strips, and the strips
formed into belts ready for use as an abrasive.

Instead of using photo-resist materials to form the
mask, the mask can be applied by a silk screening process. In
this case, the mask is made of enplate UR 2311B silk screening
material which is UV cured after silk-screening.

Representative Drawing