MISES POUR OUTILS A DEGROSSIR LA PIERRE

SCABBLER BITS

Abrégé anglais

ABSTRACT
Title: Scabbler Bits
A bit for a scabbler comprises pointed tips separated
by chisel shaped cutting tips projecting a smaller
distance than the pointed tips. The tips are preferably
in straight rows ending in pointed tips. The tips may
be of tungsten carbide and brazed into position. The
pointed tips make indentations into the surface, and
the chisel shaped tips the break the intermediate
weakened area. The bits are used for abrading hard
ground surfaces.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A scabbler bit having a number of tips mounted thereon
and means for attachment to a scabbler characterized by a
number of pointed tips separated by chisel-shaped cutting tips
projecting from the head a smaller distance than the pointed
tips.
2. A scabbler bit according to claim 1, in which the tips
are in straight rows.
3. A scabbler bit according to claim 2, in which there is
a pointed tip at the end of each row.
4. A scabbler bit according to claim 1, with the pointed
tips and chisel-shaped tips in adjacent rows off-set with
respect to each other.

Description

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TITLE: Scabbler Bits
Description:
TECHNICAI. FIELD
The invention relates to bits for scabblers, that is
percussive machines for roughening, abrading, or
removiny projections from hard surfaces, for example
walls or ground surfaces such as roads or concrete
constructions.
BACKGROUND ART
Scabblers are known from Patent Specifications such as
U.S. 2,553,435 of sriese, G.B. 709,904 of Metropolitan,
and G.B. 1/056,011 of MacDonald, but these give little
detail of scabbler bits. However, generally speaking,
a scabbler bit comprises a head having a number of tips
mounted thereon and means for attachment to a scabbler.
The tips may be of hard cutting material such as tungsten
carbide and brazed into apertures in the head.
DISCLOSURE OF INVENTION
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A scabbler bit according to the invention has a number
of pointed tips separated by chisel shaped cutting -tips
projecting from the head a smallerdistance than the
pointed tips. In use, the pointed tips make indentations
- in the surface under treatment, and the chisel shaped
tips then break the area weakened between indentations,
removing a large amount of material per unit of energy
of impact.

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In a preferred arrangement, the tips are in straight
rows, preferably parallel to each other, preferably with
a pointed tip at the end of each row, and preferably
with the pointed tips and chisel shaped tips in
adjacent rows off-set with respect to each other. If
the scabbler head is circular, the rows can well be
along and~or parallel to a diameter of the head. The
bit can be mounted on the scabbler so that the rows are
transverse to the direction of advance of the scabbler
` in use.
;
The means for attachment of the scabbler bit to a
scabbler may comprise a shank for reception in a
cylinder of the scabbler, or a recess for a piston rod
orshank projecting from -the cylinder. A taper may be
provided between the piston rod end and the bit, the
recess possibly comprising a tapered skirt optionally
with a cross-hole for securing the rod.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a face view of a bit; and
Figure 2 is a corresponding side elevation with the
centre row of pointed tips and chisel-shaped tips in
section.
BEST MODE OF CARRYING OUT THE INYENTION
The bit shown in the drawings comprises a head 1 of
steel having five parallel transverse slots (shown in

Figure 2 only) each with a number of tungsten caxbide
pointed tips 2 and tungsten carbide chisel shaped tips
3 brazed therein. The head 1 is provided with an
integral shank 4 and a spiral circumferential groove 5
whereby the head 1 can be attached to a scabbler.
INDUSTRIAL 'APPL'ICAB'ILITY
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In use, the shank 4 enters an end of a cylinder (not
shown) of a scabbler,-a coil spring (not shown) is
engaged with one end in the groove 5, and th other end
on the end of the cylinder, to retain the head in
position. A piston slidable under motive fluid pressure
in the cylinder strikes the free (left hand) end of the
shank 4 and drives the head 1 against the surface under
treatment,