SCABBLER BITS

Abstract: A bit (1) for a scabbler comprises pointed tips (2) separated by chisel shaped cutting tips (3) 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 then break the intermediate weakened area. The bits are used for abrading hard ground surfaces.

Description: TITLE: Scabbier Bits Description; TECHNICAL " FIELD The invention relates to bits for scabblers, that is percussive machines for roughening, abrading, or removing 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 Briese, G.B. 709,904 of Metropolitan, and G.B. 1,056,011 of MacDonald, but these give little detail of scabbier bits. However, generally speaking, a scabbier bit comprises a head having a number of tips mounted thereon and means for attachment to a scabbier. The tips may be of hard cutting material such as tungsten carbide and brazed into apertures in the head. DISCLOSURE OF INVENTION A scabbier 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. In a preferred arrangement, the tips are in straight rows, preferably parallel to each other, preferably wi 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 scabbier 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 scabbier so that the rows ar transverse to the direction of advance of the scabbier 10 in use. The means for attachment of the scabbier bit to a scabbier may comprise a shank for reception in a cylinder of the scabbier, or a recess for a piston rod orshank projecting from the cylinder. A taper may be 15 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 0 . 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 INVENTION The bit shown in the drawings comprises a head 1 of " 5 steel having five parallel transverse slots (shown in OMPI Figure 2 only) each with a number of tungsten carbide 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 scabbier. INDUSTRIAL- APPLICABILITY In use, the shank 4, enters an end of a cylinder (not shown) of a scabbier, a coil spring (not shown) is engaged with one end in the groove 5, and'the 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.

Claims: • CLAIMS 1. A scabbier bit having a number of tips mounted thereon and means for attachment to a scabbier characterised by a number of pointed tips (2) separat by chisel shaped cutting tips (3) projecting from the head (1) a smaller distance than the pointed tips (2) 2. A scabbier bit according to claim 1 in which -the tips are in straight rows. 3. A scabbier bit according to claim 2 in which the is a pointed tip at the end ' of each row. 4. A scabbier bit according to claim 1 with the pointed tips and chisel shaped tips in adjacent rows off-set with respect to each other. 5. A scabbier bit as herein described with referenc to the drawings.

Inventors: FURBY J
Applicants: FURBY J, JOAD ENG LTD
Application year: 1979
Main classification: B28D1
IPC codes: B08B1, B28D1