GB2168644A - Glueing machine - Google Patents

Abstract

A glueing machine, especially suitable for glueing wood by radiofrequency techniques, comprises a bed for receiving an assembly of pieces to be glued with interposed adhesive. The machine has a hinged counterweighted manually operable lid 4 which can be locked 16 to the machine base and means 10 for applying vertical pressure to the assembly when the lid is locked. Further means 20 are provided for applying side and end pressure to the assembly. <IMAGE>

Description

SPECIFICATION Glueing machine This invention relates to a glueing machine and is particularly, although not exclusively, concerned with a glueing machine for glueing wood and wood based materials using the technique of radiofrequency glueing.

Radiofrequency glueing is a known technique for speeding up the setting of glued joints and is particularly used for wood and wood based materials in the construction of materials for furniture, joinery and structural beams. Machines suitable for glueing require means to exert the necessary pressure on the assembly of wood and adhesive. Previously proposed machines have differed in design dependent on the intended product.Such machines include edge jointers for making butt joints for articles such as table tops, static laminators for making heavy sections such as structural beams, straight edge lipping machines for applying wooden lippings on the edges of chipboard used for example to construct reproduction furniture, tray lipping machines for applying up to four lippings to chipboard and curved shape machines involving pressing a shape from structural veneers using a male and female mould for example to manufacture chair backs. It can be seen from the above that each machine has a limited range of application. In particular it has been found impractical to make products of other than simple shape.

It is known to provide a basic edge jointing machine with an enclosed bed, the assembly to be joined being slid into the bed from the side and then pressure applied evenly to the top and front of the assembly while the assembly is subjected to radiofrequency waves to facilitate glueing. Such machines can only produce simple edge or butt joints but can be modified to act as tray lipping machines by sliding into the bed a tray of fixed dimensions packed with the assembly to be glued. Means may be provided to apply pressure to one or more sides of the tray. Such a machine can clearly only be used for assemblies of limited dimensions and simple conformation.

Alternative edge jointing machines have been proposed with a bed which allows easy access to the assembly to be glued by the provision of a hinged lid. In operation, the lid is lowered using an air cylinder to apply pressure to the top of the assembly. The use of such power operated lids is considered to have risks from the safety aspect.

The present invention seeks to provide glueing machines which are free of some or all of the above-mentioned defects.

According to one aspect of the invention, 1 provide a glueing machine comprising a bed for receiving an assembly of pieces to be glued provided with interposed adhesive and independently operable means for applying pressure to the assembly to facilitate glueing in three directions substantially at right angles, the means for applying pressure in at least one direction being retractable.

Preferably, the machine comprises means for applying substantially vertical pressure, means for applying side pressure and means for applying end pressure, the latter means being retractable.

According to a second aspect of this invention, 1 provide a glueing machine comprising a bed for receiving an assembly of pieces to be glued provided with interposed adhesive, the bed having a base portion and a hinged counterweighted manually operable lid provided with means whereby the lid can be locked to the base portion and means for applying substantially vertical pressure to the assembly when the lid is locked.

Preferably, the vertical pressure is applied from below the assembly by providing the base portion with rising bed means. Preferably, this form of the invention also has independently operable means for applying pressure in three directions substantially at right angles, the means for applying pressure in at least one direction, preferably in the end direction, being retractable.

The glueing machine is preferably provided with means for supplying radiofrequency waves to the assembly to be glued, although the machine is suitable for use in alternative glueing techniques. The pieces to be glued are usually wood or wood based, but the invention is applicable to the glueing of other materials, such as plastics. The adhesive used can be any of those conventionally employed, such as polyvinyl acetate, resorcinol and ur ea/formaldehyde based adhesives.

One form of the invention will now be described, with reference to the accompanying drawings, wherein: Figure 1 is a schematic side view of a glueing machine; Figure 2 is a fragmentary front view of the machine of Figure 1; and Figure 3 is a plan view of an assembly suitable for glueing in the machine of Figure 1.

Figures 1 and 2 show a radiofrequency glueing machine comprising a base 2 and lid 4.

Base 2 comprises a fixed frame 6 within which is mounted a rising bed portion 8, surmounted by a lower pressure plate 9. Bed portion 8 can be raised in a substantially vertical direction by pneumatic pressure applied via air cushions 10 operated by suitable pressure control means (not shown). Lid 4 carries pressure plate 5 and is hinged at 12 to fixed frame 6 and is provided with a counterweight 14. Thus, the lid can only be ciosed by exerting downward pressure on the front of the lid and locking the lid with front locking means 16 to the frame 6. Pressure plates 5 and 9 together define a space 3 for receiving an as sembly to be glued.

The provision of counterweight 14 and locking means 16 ensures that the lid can be operated manually and avoids the need for powered pressure closure means. Thus, the danger of inadvertent closure while positioning materials in the machine is avoided. The provision of rising bed portion 8 ensures that an even vertical pressure can be applied to materials within the machine positioned in space 3 and that the lid 4 can be of lightweight construction since it carries no pressurising means. However, alternatives to rising bed portion 8 can be employed, for example, for applying top pressure to an assembly in space 3 in conjunction with the locking arrangement at the front portion 18 of frame 6.

In addition to means for applying vertical pressure to an assembly in space 3, the machine comprises means for applying side pressure by the provision of a ram 20 operated by air cushioning means 21 linked to the pressure controi means. Usually only one front ram 20 will be necessary, the back of the machine having a stop 22. Of course, pressure could be applied from both front and back, if desired.

Furthermore, as shown in Figure 2, the machine has means to apply end pressure comprising, at one end, a ram 24 operated by air cushioning means 25 linked to the pressure control means, and, at the other end, suitable stop means (not shown). Both the ram and the stop means can be moved in the vertical direction by pneumatic cylinders 26 mounted on frame 6. As a result, the end pressure means can be in operative position, as shown in Figure 2; or can be retracted, for example when it is desired to accommodate an assembly which is longer than the machine or when it is desired to feed assemblies to the machine from the end, for example by a belt feeding mechanism. Rams 24 may, if desired, be provided at both ends and/or the rams may be in two separately operable sections to conserve energy when only limited pneumatic pressure is required.The end pressure means may alternatively be raised to an inoperative position or moved sideways.

Plates 5 and 9 are of metal such as aluminium to act as terminals for the application of radiofrequency from a suitable source (not shown). Plates 5 and 9 may be split so that it is possible to maximise power flow for a particular size of assembly. The plates may carry a protective non-stick coating, for example of polypropylene.

In use, assemblies to be glued are positioned on plate 9, for example from above or by belt feed from the end, with, if necessary, interposition of suitable mould forming members to fill the space 3. Several assemblies may be glued at once dependent on size. If necessary, the throat height between plates 5 and 9 can be varied, for example by altering the locking position of locking means 16 and by providing means for raising and lowering the position of hinge 12. 1 have found that the throat height can be adjusted from 10 mm to 200 mm.

Figure 3 illustrates the glueing procedure possible for an assembly 28 of complex shape. Assembly 28 comprises several thin layers of wood with interposed adhesive positioned on plate 9 and surrounded by male mould members 29 and female mould members 30. When the lid (not shown) is locked, so that the assembly is pressed firmly, pressure can be applied in both side and end directions, as shown by the arrows 21, together with radiofrequency to facilitate glueing.

A complex shape can, therefore, be produced simply in a single step.

It will be appreciated that the machine shown has considerable versatility, being suitable for accommodating work of many shapes and sizes and for carrying out edge jointings and lipping operations and for making laminated or solid curved constructions and for making large constructions such as solid wood panelled 'doors in a single operation.

Claims (9)

1. A glueing machine comprising a bed for receiving an assembly of pieces to be glued provided with interposed adhesive, the bed having a base portion and a hinged counterweighted manually operable lid provided with means whereby the lid can be locked to the base portion and means for applying substantially vertical pressure to the assembly when the lid is locked.

2. A glueing machine according to claim 1 wherein the base portion is provided with means for raising the bed, whereby the vertical pressure is applied from below.

3. A-glueing machine according to claim 1 or 2 wherein the vertical pressure is applied by pneumatic means.

4. A glueing machine according to claim 1, 2 or 3 comprising means for supplying radiofrequency waves to the assembly to be glued.

5. A glueing machine according to any one of the preceding claims, -wherein the machine comprises independently operable means for applying side pressure and/or end pressure.

6. A glueing machine according to claim 5, wherein the means for applying side pressure comprises a pneumatically controlled ram.

7. A glueing machine according to claim 5 or 6 wherein the means for applying end pressure comprises a pneumatically controlled ram.

8. A glueing machine according to any one of claims 5 to 7 wherein the means for applying end pressure are retractable.

9. A glueing machine substantially as shown in the accompanying drawings and described herein with reference thereto.