AU645207B2

AU645207B2 - Improvements in plasterboard

Info

Publication number: AU645207B2
Application number: AU18151/92A
Authority: AU
Inventors: William Clifford Tucker
Original assignee: PROFILES IN PLASTER Pty Ltd
Current assignee: PROFILES IN PLASTER Pty Ltd
Priority date: 1991-07-08
Filing date: 1992-06-10
Publication date: 1994-01-06
Anticipated expiration: 2012-06-10
Also published as: AU1815192A

Description

645207

AUSTRALIA

Patents Act 1990 S. 00 0 9 Name of Applicant WILLIAM CLIFFORD TUCKER Actual Inventor WILLIAM CLIFFORD TUCKER Address for Service GRANT ADAMS COMPANY, Patent Trade Mark Attorneys Level 9, National Mutual Centre, 144 Edward Street, BRISBANE. QLD. 4000

AUSTRALIA.

Invention Title "IMPROVEMENTS IN PLASTERBOARD" Details of Associated Provisional Applications Numbers PK7111 The following statement is a full description of the invention including the best method of performing it known to me.

THIS INVENTION relates to improvements in plasterboard.

A butt joint occurs where the square cut ends of plasterboard sheets meet, and should be made between joists, battens or studs.

It should be back-blocked with strips of plasterboard a minimum of 400mm wide, spanning the full width of the sheet, and overlapping the edges of the adjoining sheets by In a simple installation on a wall, where access can be gained behind the butt joint, the sheets are positioned and nailed to the wall studs. A packing strip is placed along the face of the butt joint and temporary battens are nailed to the studs to cause the packing strip to form a depression approximately deep evenly across the full length of the joint. The back block is fixed to the back of the sheets with cornice adhesive. When the adhesive has set, the Stotemporary battens and packing strip are removed and a hollow formation suitable for jointing remains.

S"Flush jointing, using several layers of cement and reinforcing tape by the known method, eg.

illustrated in the brochures distributed by "CSR Gyprock" and "Boral" (trade marks) can then be carried 25 out to complete tne joint.

It is an object to provide a plasterboard sheet which has at least one side edge profile to simplify the butt jointing method.

It is a preferred object to provide a simplified method for butt-joint plasterboard sheets.

It is a further preferred object to provide an apparatus used to form the profile in the sheets.

Other preferred objects will become apparent from the following description.

In a first aspect, the present invention resides in a method of forming a plasterboard sheet for butt jointing including the steps of: cutting a slot or groove in the plaster core, along at least one side edge of the plasterboard sheet, under the paper liner; applying an adhesive or glue to the plaster core and/or the under side of the paper liner along the slot or groove; and adhering the paper liner to the plaster core to form an external groove or depression in the face of the sheet along the side edge.

Preferably, the slot or groove is cut so that a thin layer of plaster remains on the underside of the paper liner and the thin layer of the plaster is adhered to the *laster core, the thin layer preventing (or reducing) crinkling of the paper liner due to the water base of the adhesive or glue.

In a second aspect, the present invention resides -n a tool to cut the slot or groove in the 20 plasterboard as hereinbefore described, including: o: i a router having a drive spindle; a cutting wheel on the drive spindle; and a cover mountable on the router having guide 0 means to engage the side edge of the sheet so arranged 25 that the cutting wheel cuts a slot or groove in the plaster core below the paper liner.

2.ored Preferably, the cover (and guide means) is formed of transparent material, eg. polycarbonate.

0 Preferably, dust extractor means are provided adjacent the cutting wheel.

In a third aspect, the present invention resides in a plasterboard sheet formed by the method hereinbefore described.

To enable the invention to be fully

AL,

9 understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which: FIG 1 is a side elevational view of the apparatus; FIG 2 is a similar view showing the apparatus in use; FIG 3 is an end elevational view of a side edge of the plasterboard sheet after the slot or groove has been cut; FIG 4 is a similar view of the completed side edge; FIG 5 is a rear perspective view, from above, of the apparatus; and FIG 6 is a front perspective view, from below, of the apparatus.

Referring to FIG 3, the plasterboard sheet has a plaster core 11 between front and rear paper liner S 12, 13.

By the apparatus to be hereinafter described, a groove 14 is cut along the side edge 15 of the sheet and a thin layer, eg. 0.1-1 mm of plaster 16 is left on the under side of the front paper liner 12 so that the latter will not be affected by the water-base of the glue.

25. The glue is applied to the core 11 and/or the plaster on the front paper liner 12 and the paper liner 12 is pressed into contact with the core 11 to form the depression 17 along the side edge 15 of the plasterboard sheet. Preferably, the depression is 1-10mm, more preferably 2-5mm deep.

In use, sheets 10 are fixed to the studs, joists or battens of the walls or ceilings with the adjacent side edges butted together and a back board (not shown) may be affixed using cornice cement.

The butt joint can then be finished with a layer of cement, the application of reinforcing tape along the joint, one or more layers of cement and sanding. The use of the packing strip and temporary battens is eliminated, as may be the back board, and the plaster has a neater, more consistent depression to fill at the butt joint.

Referring now to FIGS 1-3 and 5 and 6, a standard router 20 has a motor housing 21 and a base 22, with at least one slot in the base or between the legs 23 securing the base 22 to the housing. A drive wheel 24 (eg. 2-5mm thick and with peripheral teeth 25, is fixed to the drive spindle 26 of the router.

A polycarbonate cover plate 27, which may be fitted with a handle, has a pair of guides 29, 30 which engage the side edge 15 of the plasterboard sheet and defines the width of the groore 14 to be cut in the plaster core 11. The distance between the top of the cutting wheel 24 and the underside of the cover plate 27 9**o determines the thickness of the plaster layer left on the front paper liner 12, while the thickness of the cutting wheel 24 determines the depth of the groove 14.

A dust extractor chamber 31 is connected to a vacuum source (not shown) via an exhaust pipe 32. The chamber has side walls 33, 34 and a bottom cover (below the cutting wheel) so that the plaster cut from 25 the core can be sucked away to leave a cleanly cut 99.. groove 14 for the application of the adhesive or glue.

While a purpose built machine may be used, the modified commercial router, and special cutting wheel will provide an efficient cut in the core.

It will be readily apparent to the skilled addressee that the method of butt-jointing is much quicker, easier and consistent than known methods, and the preparation of the boards can be effected quickly using the modified router.

Various changes and modifications may be made to the embodiments described and illustrated without departing from the scope of the present invention defined in the appended claims.

f so Sao** 0 0 0C 0

Claims

1. A method of forming a plasterboard sheet for butt-jointing to a similar sheet, including the steps of: cutting a slot or groove in the plaster core, along at least one side edge of the plasterboard sheet, under the paper liner; applying an adhesive or glue to the plaster core and/or to the underside of the paper liner along the slot or groove; and adhering the paper liner to the plaster core to form an external groove or depression in the face of the sheet along the side edge of the sheet.

2. A method according to Claim 1 wherein: the slot or groove is cut so that a thin layer of plaster remains on the underside of the paper a liner and the thin layer is adhered to the plaster core.

3. A tool to cut the slot or groove in the S: plaster board sheet claimed in Claim 1 or Claim 2, the 20 tool including: rrr S"a router having a drive spindle; a cutting wheel on the drive spindle; and a cover mountable on the router having guide means to engage the side edge of the sheet so arranged 25 that the cutting wheel cuts a slot or groove in the plaster core below the paper liner.

4. A tool as claimed in Claim 3 wherein: the cover and guide means are formed of transparent plastics material.

5. A tool as claimed in Claim 3 or Claim 4 wherein: dust extractor means are provided adjacent the cutting wheel.

6. A plasterboard sheet formed by the method as claimed in Claim 1 or Claim 2. 8

7. A method of forming a plasterboard sheet, as claimed in Claim 1 or Claim 2, substantially as hereinbefore described with reference to the accompanying drawings.

8. A tool as claimed in any one of Claims 3 to substantially as hereinbefore described with reference to the accompanying drawings. DATED this twenty-sixth day of October 1993. WILLIAM CLIFFORD TUCKER By his Patent Attorneys GRANT ADAMS COMPANY. S o S 0 ft S o

9 ABSTRACT A plasterboard sheet, arranged to be butt- jointed to a similar sheet, has an external depression (eg. 2-5mm deep) provided in the front face along one side edge of the sheet. A router, fitted with a cutting wheel, has a cover and guide which control the depth and width of a slot or groove cut in the side edge of the plasterboard core, under the paper liner. Glue or adhesive is placed in the slot or groove and the paper liner is depressed to adhere to the plaster core to form the external groove or depression. e*0ee 0* C Ci..