Twin blade V-groove cutter

Abstract: A cutting apparatus adapted to make a V-shaped cut in a surface is described. The apparatus has two powered disc blades (2) mounted on a carriage means (4) wherein the blades (2) are angled towards each other such that the cutting edges (5) of the blades are proximate. The cutting apparatus may be supported by an elongate frame (32) able to track the carriage means along the surface. The cutting apparatus of the present invention creates a V-shaped cut in a surface from which any remaining material (68) can be removed to form the track for a wire or conduit etc.

Description: This invention relates to a cutting apparatus for cutting tracks in walls and floors, etc. Tracks are cut in walls, usually of cementatious material, for accommodating wires, pipes, etc., or conduits for wires, pipes, etc, which can then be hidden in the wall behind a plastered finished surface. GB 2 202 788A describes a cutting apparatus having a power saw with two parallel blades mounted on a frame designed to create cuts in a wall. The frame locates the power saw next to the wall, and the saw is moved up and down the frame to create the cuts. However, the material remaining between the cuts still needs to be chipped out to form the track, and doing this with chisel and hammer involves further time and effort, as well as still creating dust and debris that needs to be cleared up. According to the present invention, there is provided a cutting apparatus adapted to make a V-shaped cut in a wall or floor surface so as to cut a track for accommodating wires or pipes, the apparatus having two powered disc blades mounted on a carriage means for movement along or across the surface, wherein the blades are angled towards each other such that the cutting edges of the blades are proximate wherein the carriage means comprises two arms and connecting support, each arm supporting one axle on which a blade is mounted. The cutting apparatus of the present invention creates a V-shaped cut in a surface, from which any remaining material can be removed to form the track for a wire or conduit etc. Preferably, the gap between cutting edges of the blades is such as to leave a 'neck' connecting the material that passes between the cutting edges of the blades during cutting to the surface. The neck of connected material can then easily be broken, e.g. by a screwdriver, to remove all the remaining material wholly or substantially complete, thereby reducing significantly the mess and debris created. Preferably, one or more streams of liquid, e.g. water sprays, are directed at or near the cutting edges of the blades during use. The liquid(s) dampen down and reduce, usually considerably, the amount of dust created during the cutting operation. This reduces atmospheric pollution and visibility problems. A collecting means, e.g. bucket, could be located at the bottom of the surface being cut to collect the liquid and dust mixture to further reduce dirt and mess. Preferably also, each arm is movable between a disengaged starting position prior to cutting and an engaged cutting position. The arms may be movable by rotation about pivotal axes between the connecting support and the arms. Movement of the blades between a starting position away from the surface and an engagement position within the surface allows the blades to more easily engage the surface at an angle, and to create a clean cut with connected material remaining between the cuts. Preferably further, the blades are powered by a central power source, e.g. an electric or petrol motor, with a split transmission means to the blades. Because the blades are not parallel, the transmission means must be split in angular fashion, e.g. by using bevelled gears. The split transmission means ensures that both blades are running at the same speed. The transmission means preferably includes at least one drive pulley for each blade. This allows easy adjustment of the tension as desired or necessary, and for adjustment to account for wear of the blades. The angle between the blades may be as desired or necessary, and is preferably adjustable according to the cut required or surface to be cut. Preferably the angle is or is near 60°. The cutting apparatus may be used as a hand-held device. Preferably, the cutting apparatus is attached to or includes a support. This includes the carriage means being supported by an elongate frame as described in GB 2 022, 788 A. Said frame has two parallel guides to track the carriage means along a surface, e.g. a wall. The cutting apparatus may be used on any suitable surface, e.g. wall, floor, ceiling, road, pavement, etc. Because it does not chip, shatter or otherwise destroy the surface (compared with chiselling, etc.), the cutting apparatus may be used on newly cemented surfaces which are still "fresh", (e.g. two days old orso). This speeds up considerably the building or finishing of a room or a house where it has previously been necessary to wait several days before a cemented wall would be dry enough to support itself under the effect of a chisel. Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:- Fig. 1 is a front view of a cutting apparatus according to the present invention on a support frame. Fig. 2 is a side view of the apparatus and support frame of Fig. 1; Fig. 3 is an enlarged plan view of the apparatus of Fig. 1; and Fig. 4 is a diagrammatic side view of part of the cutting apparatus of Fig. 1. Referring to the drawings, they show a cutting apparatus having two disc blades 2 mounted on a carriage 4. The blades 2 are angled towards each other such that their cutting edges 5 are proximate. As shown more clearly in Fig. 3, the blades 2 are mounted on two first axles 6, supported by two radial arms 8. Also on the first axles 6 are first pulley wheels 10. Two second axles 12, supported by two mounting plates 14, have two second pulley wheels 16 co-linear with the first pulley wheels 10. Between the first and second pulley wheels 10,16 are first drive belts 17 (shown in dotted line). The second axles 12 extend into a transmission box 18 and have bevelled cog wheels 20 at their ends so that the second axles 12 rotate together. One second axle 12 also has a drive pulley wheel 22 which is co-linear with the drive wheel of an electric motor 24. Between the latter wheels is a second drive belt 26. In use, the electric motor 24 drives the drive pulley wheel 22, hence both second axles 12 (via the transmission box 18), both first axles 6 and thus the blades 2. Whilst not shown in Fig. 3 for clarity, Figs. 1 and 2 show blade guards 28 and first drive pulley guards 30 to provide protection against these parts during use. The carriage 4 is mounted on an elongate support frame 32 having two parallel guides 34, top and bottom cross-members 36, and carriage support cross members 38. The carriage cross members 38 track the guides 34 using guide wheels 39, and the upper carriage cross member 38 is connected, e.g. by a wire rope 40 entrained around frame pulleys 41, to a winding mechanism 42. The construction and operation of the winding mechanism 42 corresponds to that as described on pages 5 onwards of GB 2 202 788 A. Rotation of the handle 44 causes winding of the reel 46 around which the wire rope 40 is entrained, causing the carriage 4 to move longitudinally along the guides 34. The support frame 32 includes spacer bars 48 to ensure correct distancing of the frame 32 from the surface 50 to be cut. The frame 32 has wheels 52 to assist transport of the frame 32 for relocation, and a piston and cylinder arrangement 58 which can rotate a foot bar 60, which bar 60 is rotatable about the axis of the wheels 52 to secure the frame 32 in position for use. Fig. 4 shows diagrammatically the operation of engagement of the blades 2 into a surface 50. Whilst angled blades 2 (that is, blades directed to be at an angle to the surface) could be driven into the surface directly, or possible with ease when the cutting apparatus is freely held or supported, it is preferred for the operation of the blades 2 on the carriage 4 and frame 32 in this embodiment for the blades 2 to be driven into the surface 50 vertically. For this, the arms 8 supporting the blades 2 are rotatable about the second axles 12 using bushes (not shown) on the axles 12. The arms 8 are also attached to cutting handles 62 via three-point linkages 64. One end of the cutting handles 62 is attached to the mounting plates 14, whilst the other end extends outwardly from the carriage 4. Movement of the handles 62 rotates the arms 8 and hence blades 2. The two handles 62 may be linked or separate. In use, the frame 32 is located against a desired surface 50. The spacer bars 48 provide correct distancing of the frame 32 from the wall 50. A handle 66 of the piston and cylinder arrangement 58 extends the piston downwardly to secure the foot bar 60 against a bottom surface (e.g. floor) and secure the frame 32. Preferably, the top cross member 36 abuts an upper surface (e.g. ceiling), or spacers can be put therebetween to confirm such engagement. With the carriage 4 in the desired position along the frame 32, the motor 24 is started to rotate the blades 2, and the blades 2 are introduced into the surface 50 by moving the cutting handles 62 to a transverse position (Fig. 4). As shown in Fig. 3, the blades 2 create a V-cut, but with the bulk of material 68 (that not directly cut by the blades 2) still held to the surface by a neck 70. The carriage 4 is progressed along the surface 50 by guidance within the frame 32 to create the required V-cut. Water is directed via nozzles 72 at the cutting to reduce the heat of the blades 2, and to dampen and reduce dust created by the cutting. Once finished, the blades 2 are withdrawn from the surface 50 by moving the cutting handles 62 upwardly. Once the cutting apparatus is removed, the remaining material 68 is very simply and easily removed by breaking the neck 70, possibly with just a screwdriver. This material 68, being the bulk of material removed for the track created, is thus removed still in solid form, rather than having been chipped or chiselled away (with attendant debris and mess). Along with removal of the dust created during cutting by the water spray, the present invention creates little mess and debris, especially scattered debris, requiring time and effort to clear away. Variations and modifications can be made without departing from the scope of the invention described above and as defined in the claims hereinafter.

Claims: A cutting apparatus adapted to make a V-shaped cut in a wall or floor surface (50) so as to cut a track for accommodating wires or pipes , the apparatus having two powered disc blades (2) mounted on a carriage means (4) for movement along or across the surface (50) wherein the blades (2) are angled towards each other such that the cutting edges (2) of the blades are proximate wherein the carriage means (4) comprises two arms (8) and a connecting support, each arm (8) supporting one axle (6) on which a blade (2) is mounted. A cutting apparatus as daimed in Claim 1 characterised in that the gap between cutting edges (5) of the blades (2) is adapted to leave a 'neck' (70) of material still connected to the surface (50) after passage of the cutting apparatus. A cutting apparatus as claimed in Claim 1 or Claim 2, characterised in that one or more streams or sprays of liquid are directed at or near the cutting edges (5) of the blades (2) during use. A cutting apparatus as daimed in Claim 1, 2 or 3, characterised in that each arm (8) is movable between a disengaged starting position prior to cutting and an engaged cutting position. A cutting apparatus as claimed in Claim 4, characterised in that the arms (8) are movable by rotation about pivotal axes between the connecting support and the arms (8) to move the blades (2) between a starting position away from the surface (50) and an engaged position within the surface (50). A cutting apparatus as daimed in any one of the preceding daims, characterised in that the blades (2) are powered by a central power source (24) with a split transmission means to the blades (2). A cutting apparatus as claimed in Claim 6, characterised in that the transmission means includes one or more bevelled gears (20). A cutting apparatus as claimed in Claim 6 or 7, characterised in that the transmission means includes at least one drive pulley for each blade (2). A cutting apparatus as claimed in Claim 8, characterised in that the tension in the or each pulley is adjustable. A cutting apparatus as claimed in any one of the preceding claims, characterised in that the angle between the blades (2) is adjustable. A cutting apparatus as claimed in any one of the preceding claims, characterised in that the angle between the blades (2) is or is near 60°. A cutting apparatus as claimed in any one of the preceding claims, characterised in that the cutting apparatus is attached to or includes a support. A cutting apparatus as claimed in Claim 12, characterised in that the support is an elongate frame (32) having two parallel guides (34) to track the carriage means (4) along the surface (50). A cutting apparatus as claimed in Claim 13, characterised in that the elongate frame (32) includes a wheeled assembly (52, 58, 60) mounted at one end of the frame (32), the assembly being adapted to be surface-engaging and to help secure the frame against the surface (50).

Inventors: BROWN ROBERT, SPEEDIE ANDREW, BROWN, ROBERT, SPEEDIE, ANDREW
Applicants: BROWN ROBERT, SPEEDIE ANDREW, BROWN, ROBERT, SPEEDIE, ANDREW
Application year: 1997
Main classification: B28D1
IPC codes: B23D45, B28D1, B23D47