AU2002315901A1 - Groove cutter - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): EXI-FORMA PTY LTD A.C.N. 102 925 379 Invention Title: GROOVE CUTTER The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 GROOVE CUTTER FIELD OF THE INVENTION The present invention relates to a groove cutter, of particular but by no means exclusive application for cutting plasterboard and, in particular, in providing a suitable groove in plasterboard so that the plasterboard can be provided with an angle. The invention also relates to a method of forming external angles in, for example, plasterboard by means of the aforementioned groove cutter.

BACKGROUND OF THE INVENTION In the construction industries, grooves are typically formed by means of routing devices. However, particularly when a groove is to be provided in a piece of plasterboard (comprising plaster to which a stiff external facing paper is adhered on both faces), large quantities of dust are produced. Excessive dust and associated respiratory health risks are avoided only by means of time consuming and expensive safety measures. In addition, such work environments are closely monitored by unions, occupational health and safety officials, and insurers; consequently, such work must generally be formed off-site. All these factors lead to greater expense and introduce delays.

Further, existing methods for forming external angles in plasterboard generally comprise placing a metal external angle over a rough plasterboard corner and attaching it thereto by means of staples. The corner (and particularly the metal angle, which is generally of galvanised steel) is then stopped and sanded to provided a smooth finish.

Although this approach can be avoided by forming a groove in the plasterboard and bending the plasterboard to form the required angle, this is done by the techniques (as described above) that introduce cost and raise safety issues.

3 SUMMARY OF THE INVENTION It is an object of the present invention to provide a groove cutter and method of forming external angles that can be readily performed on a construction site.

The present invention provides therefore, a groove cutter for forming a groove in a material, a groove cutter comprising: a blade having at least one cutting edge for forming said groove, and having a profile corresponding to the profile of said groove, wherein said groove is formed by drawing said cutter across said material.

Preferably the groove cutter includes a blade holder for manipulating said blade. Preferably said groove cutter has a forward cutting edge and a rearward cutting edge.

In one embodiment, the groove cutter includes attachment means for attaching said blade to a blade holder for manipulating said blade.

The attachment means can comprise any suitable member or aperture for engaging a blade holder, whether that blade holder is intended to be manipulated manually by means of some other tool. The attachment means can comprise apertures in the blade or an extension of the blade (and, in one embodiment, in a depth guide provided integrally with the blade). The attachment means can also comprise a portion or extension of the blade that is attached to or held by the holder.

Preferably said groove cutter includes a depth guide for determining a maximum depth to which said groove cutter can cut said groove, so that a groove of predetermined and uniform depth can be cut in said material. More preferably said depth guide is attached to said blade and, in use, is pressed against said material when said groove 4 is being formed.

The depth guide and blade holder may be provided in a single integer.

Preferably said attachment means comprises lateral extensions of said blade.

Preferably said depth guide and said blade are formed integrally.

In one embodiment the blade holder has a lower periphery that also comprises a depth guide.

In another embodiment the groove cutter includes a groove guide corresponding to a desired path of said groove.

Thus, the groove guide could comprise a straight, elongate member along or within which the blade is drawn. The groove guide, on the other hand, could be curved, circular or otherwise so that a predetermined line can be followed by the cutter.

In one embodiment the groove guide is straight and includes a threaded rod for engaging a correspondingly threaded member that engages said blade so that said blade can be drawn parallel to said rod to form a linear groove in said material.

In another embodiment the groove guide is straight and includes a drive chain driven about at least two cogs, said chain engaging said blade so that said blade can be drawn parallel to said chain to form a linear groove in said material.

It will be understood that the engagement of the threaded member or chain and the blade may be mediated by a blade 5 holder or other suitable member.

In one embodiment, the blade includes an angle between essentially planar portions so that a straight sided Vshaped groove can be formed. In one particular embodiment, said angle is Thus, any desired acute or obtuse angle could be employed.

Alternatively, the blade can have essentially any profile.

For example, the profile could be curved (such as a Ushaped profile), square, rectangular or otherwise.

Indeed, the profile need not necessarily, in fact, become narrower at greater depth as the groove can be cut from one edge of material (such as the plasterboard) to the other. Thus, the groove could have an essentially circular shape with a narrow neck at the least deep portion of the desired groove, so that a circular ductlike passage is formed in the material indeed, in this example need not be opened but could comprise a portion of the blade joining the holder to the circular profiled portion of the blade.

In one embodiment, the cutter has a size and profile to form a groove in plasterboard substantially equal to but less than the thickness of the plasterboard such that a rear facing paper of said plasterboard remains intact once said groove is formed, whereby said plasterboard when provided with said groove can be bent along said groove and remain integral. Preferably in this embodiment the groove comprises a 900 V-shaped groove, so that a 900 angle can be formed in said plasterboard.

Preferably a cutting edge of said blade has an oblique cutting edge so that, in use, the portion of said blade deepest in said material trails the portion of said blade closest to the surface of said material.

6 In one embodiment said blade has two cutting edges, one at each end of said blade so that the groove cutter can be operated in either of two directions.

The groove cutter is preferably provided with depth adjustment means so that the depth to which said blade cuts can be adjusted, whereby the depth of said groove can be selected.

The groove cutter may have a body, said depth adjustment means comprising means for adjusting the position of said blade relative to said body. Alternatively, the groove cutter may have a plurality of legs, the depth adjustment means comprising means for adjusting the height of said legs.

The present invention also provides a method of forming an angle in a material, involving: forming a groove in said material by means of the groove cutter described above; wherein said groove has sufficient depth to allow said material to be readily bent to form said angle but leaving sufficient thickness of said material so that said material remains integral.

Preferably said groove is V-shaped.

In one embodiment, said material is plasterboard and said groove leaves the paper on one side of said plasterboard intact.

In one particular embodiment, the V-shaped groove has a 900 angle so that said plasterboard can be formed into a 900 angle, but it will be appreciated that any suitable angle can be employed, according to the intended application.

7 BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be more clearly ascertained, preferred embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view of a groove cutter according to a first preferred embodiment of the present invention; Figure 2 is a further view of the groove cutter of figure 1; Figure 3 is a further view of the groove cutter of figure 1; Figure 4 is a schematic view of the groove cutter of figure 1 in use with a piece of plasterboard; Figure 5 is a further view of the groove cutter of figure 1 in use with a piece of plasterboard, showing the formation of a groove; Figure 6 is a schematic view of a piece of plasterboard formed into a 900 edge once provided with a groove by means of the groove cutter of figure 1; Figure 7 is a view of a groove cutter according to a second preferred embodiment of the present invention; Figure 8 is a cross-sectional view through the groove cutter of figure 7 along line B-B; Figure 9 is a further view of the groove cutter of figure 7; Figure 10 is a schematic view of the groove cutter of figure 7 in use with a piece of plasterboard; Figure 11 is a view of a groove cutter guide channel according to a preferred embodiment of the present invention for forming straight grooves; Figure 12 is a further view of the channel of figure 11; Figure 13 is a view of the channel of figure 11 provided with a groove cutter comparable to that of figure 7; Figure 14 is a view of the channel of figure 11 in use with a piece of plasterboard; -8- Figure 15 is a perspective view of the channel of figure 11 in use with a piece of plasterboard; Figure 16 is a view of another guide for cutting straight grooves according to a preferred embodiment of the present invention; Figure 17 is an end view of the guide of figure 16; Figure 18 is a plan, partially cut-away view of the guide of figure 16, illustrating its chain drive mechanism; Figure 19 is a view of one end of groove cutter of figure 16; Figure 20 is a view of the groove cutter of figure 16 mounted to a linear chain drive for forming linear grooves; Figure 21 is a view similar to that of figure of the groove cutter of figure 16 in use with a piece of plasterboard; Figure 22A is a side elevation comparable to that of figure 9 of a groove cutter according to further embodiment, provided with adjustable legs for adjusting groove depth; Figure 22B is a side elevation of a variation of the groove cutter of figure 22A; Figure 22C is an end view (comparable to figure 19) of the groove cutter of either figure 22A or 22B; and Figure 22D is an end view of a variation of the groove cutter of figure 22C.

DETAILED DESCRIPTION A groove cutter according to a first preferred embodiment of the present invention is shown generally at 10 in figure 1. For clarity, in this figure (and also in figures 2 to the handle of the groove cutter 10 has been omitted for clarity.

Groove cutter 10 comprises a stainless steel blade 12 of 9 1 mm thickness, provided at its leading end 14 with a cutting edge 16. Blade 12 has a 90* bend (into the page as seen in figure 1) along its central axis forming an apex 18, while cutting edge 16 is formed obliquely so that in use the forward end of apex 18 trails the overall forward end of the blade 12.

Integrally formed with blade 12 are lateral wings 20, 22 provided with screw holes 24 for attaching to a blade holder.

Figure 2 is a side elevational view of groove cutter 10 in which the oblique formation of cutting edge 16 is apparent. The advantage of the oblique formation of cutting edge 16 is the facilitation of cutting when the groove cutter 10 is drawn through the material to be cut.

Figure 3 is a cross-sectional view of groove cutter along A-A. In this figure, the profile of groove cutter 10 is clearly visible, and in particular the 90' bend at central axis 18.

Figure 4 is a schematic view of the groove cutter 10 in use with a piece of plasterboard 30. Firstly, it should be noted that plasterboard 30 comprises compressed plaster core 32 and paper facing sheets 34 and 36. In use, groove cutter 10 (shown here in a view comparable to that of figure 2) is drawn from left to right as seen in this figure. The oblique formation of cutting edge 16 facilitates this process and, as the groove cutter 10 is advanced, the upper facing paper 34 and then the plaster 32 is cut by the groove cutter 10. However, the lower facing paper 36 is left intact.

This procedure is also depicted in figure 5, a perspective view of the groove cutter 10 once it has been advanced somewhat through plasterboard 30. A groove 38 has been 10 formed of 900 profile.

Referring to figure 6, once the groove has been completely formed from one edge of the plasterboard 30 to the other, the plasterboard can be bent 40 along the line of the groove until the services exposed by the formation of the groove meet. Because the groove was formed with a 900 profile, the plasterboard 30, once fully bent, forms a 900 angle at its vertex 42. The vertex 42, however, remains covered by facing paper 36.

Although not shown in figures 1 to 6, groove cutter includes a blade holder for convenient manipulation of the blade, attached by means of screws (not shown) located through apertures 24 in lateral wings 20,22. This holder has a broad, planar lower surface. Lateral wings 20,22 are screwed to this lower surface counter-sunk so that the lower surface of the handle and the lower surface of lateral wings 20,22 are co-planar. This is so that, in use, the lower surface of the holder and the lateral wings 20,22 define a single depth guide that is pushed across the surface of the plasterboard, whereby defining the maximum depth to which the blade 16 can cut the groove.

A groove cutter according to a second preferred embodiment of the present invention is shown generally at 50 in figure 7. Groove cutter 50 includes a blade 52 and a blade holder 54. The blade 52 is attached to the holder 54 by means of four screws 56. Holder 54, as shown in this figure, has an inverted, generally U-shaped form, with a forward end 58 and rear end 60. The rearwardly directed arms 62 of holder 54 define a gap within which the blade 52 is located. The location of blade 52 within holder 54 is shown in cross-section B-B in figure 8. As is particularly apparent in figure 8, blade 52 of this embodiment comprises a 90* V-shaped piece of stainless steel with a forward cutting edge 64. Although this 11 cutting edge is essentially straight (apart from a 900 bend), it may also be optionally formed obliquely by cutting edge 16 of cutter blade 10 of figure 1.

Arms 62 of holder 54 are formed with 450 inner faces so that blade 52 can be located therebetween and attached by means of screws 56 with the central axis (apex) 66 of blade 52 protruding downwardly beyond the lower face of holder 54 by a distance equal to the depth of the desired groove.

Figure 9 is a view of groove cutter 50 in side elevation, while figure 10 is a perspective view of groove cutter in use with plasterboard 68. Groove cutter 50 operates in essentially the same manner as groove cutter 10 of the first embodiment, and is advanced across the surface of plasterboard 68 to form the required groove. The lower surface of holder 54 acts as a depth gauge by maintaining the apex 66 of the blade 52 at a constant and predefined depth. As the groove cutter 50 is advanced in direction the waste of plasterboard material 72 is progressively excised. A groove 74 of predetermined depth is thereby formed.

In this embodiment, holder 54 functions both as a depth plate and as a holder for manipulation of the blade 52. A handle 76 can additionally be provided projecting upwardly from holder 54, whereby holder 54 and thereby blade 52 can be manipulated by means of handle 76.

In the embodiments described above, the groove cutter is guided by the user manually. In some cases, however, it may be advantageous to provide mechanical guidance for the groove cutter. Thus, figure 11 is a view of a guide channel 80 for guiding a groove cutter to form a straight groove of high precision.

12 Figure 11 is an end view of channel 80, which extends (as shown in figure 11) into the page according to the length of the channel, which would generally correspond to the likely length of the desired groove.

Channel 80 comprises an aluminium (or other suitable material) inverted U-shaped channel with internal lips 82.

Lips 82 and the lower portions of side walls 84 of channel retain and guide a groove cutter, such as groove cutter 50 of figure 7 modified as will be described below.

Each end of channel 80 is provided with a lower end plate 86 to maintain the rigidity of channel 80, and extending upwardly from the lower extremity of channel 80 as far as desired. Indeed, end plate 86 can extend to the top of channel 80 with allowance for the other components of channel 80 to extend therethrough as necessary.

The principle functional element of channel 80 is a elongate, externally threaded screw or rod 88 extending the entire length of channel 80 and mounted at each end in a ball-bearing race 90. Each ball-bearing race 90 is supported in a frame 92 suspended from and attached to the top 94 of the channel 80 by any suitable means, such as bolts or screws.

Referring to figure 12, one end of threaded rod 88 is driven by means of a handle 96 attached to that end (and shown schematically in this figure), although alternatively a motor could be provided to rotate the threaded rod 88.

Figure 13 is a partial side view of channel 80 provided with a groove cutter 98. Groove cutter 98 differs from groove cutter 50 of figure 7 in being provided with a internally threaded sleeve 100 for engaging the threaded rod 88. The engagement of internally threaded sleeve 100 13 and threaded rod 88 is such that, when threaded rod 88 is rotated, sleeve 100 and therefore groove cutter 98 are driven along the length of channel 80 left to right or right to left as shown in figure 13). By turning handle 96, the groove cutter 98 can be driven the length of channel 80 to form a highly linear groove in, for example, a piece of plasterboard.

Figure 14 is a schematic view of the entire guide channel 80 with internally threaded sleeve 100 (though omitting the groove cutter for the sake of clarity). A stopper 102 is located underneath channel 80 proximate the end of channel 80 at which handle 96 is provided, so that channel can, in use, be placed on a sheet of, for example, plasterboard with stopper 102 against the edge of that sheet. If desired, channel 80 can also be clamped onto the sheet to ensure maximum stability during operation.

Figure 15 is a schematic view of channel 80 provided with groove cutter 98 located within channel 80, on a piece of plasterboard 104 in which a groove 106 is to be formed.

Handle 96 is rotated such that groove cutter 98 is drawn towards the handle end of channel 80, so that the plasterboard 104 is, in effect, clamped between groove cutter 98 and stopper 102. This increases the stability of the apparatus during use.

As will be appreciated, the blade 108 of the groove cutter 98 is provided with two cutting edges ll0a and 110b at, respectively, forward and rearward ends of blade 108 so that the groove cutter can be driven in either direction within channel 80 to form a groove.

Another guide for cutting straight grooves according to a preferred embodiment of the present invention is shown generally at 120 in figure 16. This guide includes a housing comparable to the U-shaped housing of channel 14 but, instead of incorporating a threaded screw, this guide 120 has a chain 122 and a pair of cogs 124, 126 each located at one end of guide 120 about which chain 122 is driven. Cogs 124 and 126 have vertical axes. One of the cogs 124 has a vertical extension 125 extending upwardly through the casing of guide 120 so that cog 124 and therefore guide 120 can be driven, such as by an electric drill, in either direction. A groove cutter 128 (such as one similar to groove cutter 50 of figure 7) is located within guide 120 and attached to chain 122. The ends 130 of chain 122 are attached to the ends of groove cutter 128. Driving cog 124 drives chain 122 and therefore causes groove cutter 128 to be advanced along the length of the guide 120.

Figure 17 is an end view of guide 120 provided with a groove cutter 128 and located on a piece of plaster board 132. Cog 124 provided with upwardly projecting pin 134 is also shown.

Casing 136 (of aluminium or steel) of guide 120 is provided with internal lips 138 running the length of casing 136, for guiding groove cutter 128. Groove cutter 18 is provided with complementary recesses 140 for receiving lips 138.

Figure 18 is a partial cut-away plan view of guide 120, in which can be seen cogs 124,126 with chain 122 joined at ends 130 to groove cutter 128. It will be noted that the points at which chain ends 130 are attached to groove cutter 128 are aligned with the central axis of both the guide 120 and the groove cutter 130, so that groove cutter 128 is drawn from a central point. Optionally, however, cogs 124 and 126 can be located off-axis so that chain 122 is parallel to this axis and draws groove cutter 128 along the guide 120 with a tension having no lateral component.

15 Figure 19 is an end view of groove cutter 128, showing blade holder 142 with elongate recesses 140. Blade 144 is attached to blade holder 142, and a cover member 146 (to which chain 122 is affixed) is located on top of blade holder 142.

Referring to figures 20 and 21, ends 130 of chain 122 are attached to groove cutter 128 as shown, with blade 144 extending downwardly. Blade 124 is provided with forward and rearward cutting edges 146a and 146b, so that the groove cutter 128 can be operated in either direction. In use, the guide 120 is deployed in a manner similar to channel 80 of figure 15: when used to form a groove in plasterboard 148, a groove is formed leaving lower facing paper 150 intact.

Modifications within the scope of the invention may be readily effected by those skilled in the art. For example, in each of the embodiments described in detail above, the blade is fixed to the blade holder with a constant, predetermined exposed portion so that a groove of constant depth is formed. However, by conventional means it is possible to provide a blade that extends below the blade holder/depth guide to a variable degree so that grooves of different depths can be formed. Thus, referring to figure 22A, according to a further embodiment a groove cutter 152 (seen in this figure in side elevation) is provided with a series of legs 154 of adjustable height, so that the depth of blade that is exposed can be adjusted, so that the depth of the groove can be selected. Corresponding legs are provided on the other side of the groove cutter 152. The blade is not shown in this figure for the sake of clarity.

A variation of the groove cutter 152 is shown, again in side elevation, in figure 22B. The plurality of legs 154 on each side of the groove cutter 152 are replaced on each 16 side by a single continuous leg 156.

The legs 152 and 154 are adjustable in height by any suitable means. For example, the legs can be attached to the groove cutter 152 by bolts located in vertical slots in the sides of the groove cutter 152. Alternatively, for example, such bolts or pins can be receivable in multiple holes provided in vertical rows in the sides of the groove cutter 152.

The legs 152 or 154 can be seen more clearly in figures 22C and 22D, which are end views of the groove cutter 152 of figure 22A or 22B and of a variation thereof respectively. Legs 152 or 154, as can be seen from these figures, have an L section with either outwardly directed feet 156 (cf. figure 22C) or inwardly directed feet 158 (cf. figure 22D). Blade 160 is also shown in these figures.

Alternatively, a removable blade can be employed so that blades for forming different depths can be substituted as desired, as can be blades of different profiles.

It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example herein above.

Claims (20)

1. 2. A groove cutter as claimed in claim i, including a blade holder for manipulating said blade.
2. 3. A groove cutter as claimed in claim 1, including attachment means for attaching said blade to a blade holder for manipulating said blade.
3. 4. A groove cutter as claimed in claim 3, wherein said attachment means comprises lateral extensions of said blade. A groove cutter as claimed in any one of claim 2 to 4, wherein said blade holder has a lower periphery that also comprises a depth guide.
4. 6. A groove cutter as claimed in any one of the preceding claims, including a depth guide for determining a maximum depth to which said groove cutter can cut said groove, so that a groove of predetermined and uniform depth can be cut in said material.
5. 7. A groove cutter as claimed in claim 6, wherein said depth guide is attached to said blade and, in use, is pressed against said material when said groove is being formed.
6. 8. A groove cutter as claimed in any one of the preceding claims, including a groove guide corresponding to a 18 desired path of said groove.
7. 9. A groove cutter as claimed in claim 8, wherein said groove guide is straight and includes a threaded rod for engaging a correspondingly threaded member that engages said blade so that said blade can be drawn parallel to said rod to form a linear groove in said material. A groove cutter as claimed in claim 8, wherein said groove guide is straight and includes a drive chain driven about a pair of cogs, said chain engaging said blade so that said blade can be drawn parallel to said chain to form a linear groove in said material.
8. 11. A groove cutter as claimed in any one of the preceding claims, wherein said blade includes an angle between essentially planar portions so that a straight sided V-shaped groove can be formed.
9. 12. A groove cutter as claimed in claim 11, wherein said angle is
10. 13. A groove cutter as claimed in any one of the preceding claims, wherein said blade has a size and profile to form a groove in plasterboard substantially equal to but less than the thickness of the plasterboard such that a rear facing paper of said plasterboard remains intact once said groove is formed, whereby said plasterboard when provided with said groove can be bent along said groove and remain integral.
11. 14. A groove cutter as claimed in claim 13, wherein said groove comprises a 90* V-shaped groove, so that a angle can be formed in said plasterboard. A groove cutter as claimed in any one of the preceding claims, wherein said blade has an oblique 19 cutting edge so that, in use, the portion of said blade deepest in said material trails the portion of said blade closest to the surface of said material.
12. 16. A groove cutter as claimed in any one of the preceding claims, wherein said blade has two cutting edges, one at each end of said blade so that the groove cutter can be operated in either of two directions.
13. 17. A groove cutter as claimed in any one of the preceding claims, wherein said groove cutter has a forward cutting edge and a rearward cutting edge.
14. 18. A groove cutter as claimed in any one of the preceding claims, wherein said groove cutter is provided with depth adjustment means so that the depth to which said blade cuts can be adjusted, whereby the depth of said groove can be selected.
15. 19. A groove cutter as claimed in claim 18, wherein said groove cutter has a body, said depth adjustment means comprising means for adjusting the position of said blade relative to said body.
16. 20. A groove cutter as claimed in claim 18, wherein said groove cutter has a plurality of legs, said depth adjustment means comprising means for adjusting the height of said legs.
17. 21. A method of forming an angle in a material, involving: forming a groove in said material by means of the groove cutter according to any one of the preceding claims; wherein said groove has sufficient depth to allow said material to be readily bent to form said angle but leaving sufficient thickness of said material so that said 20 material remains integral.
18. 22. A method as claimed in claim 21, wherein said groove is V-shaped.
19. 23. A method as claimed in claim 22, wherein said V- shaped groove has a 900 angle so that said plasterboard can be formed into a 900 angle.
20. 24. A method as claimed in either claim 21 or 22, wherein said material is plasterboard and said groove leaves the paper on one side of said plasterboard intact. A groove cutter substantially as hereinbefore described with reference to figures 1 to 6 or to figures 7 to 10 or to figures 11 to 15 or to figures 16 to 21 or to figure 22A or to figure 22B or to figure 22C or to figure 22D of the accompanying drawings. Dated this 10th day of December 2002 EXI-FORMA PTY LTD By its Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia