GB2127345A

GB2127345A - Vacuum presses

Info

Publication number: GB2127345A
Application number: GB08226469A
Authority: GB
Inventors: Robert Filmer Bridgland
Original assignee: OLD ACRE ENG CO Ltd; Old Acre Engineering Co Ltd
Current assignee: OLD ACRE ENG CO Ltd; Old Acre Engineering Co Ltd
Priority date: 1982-09-16
Filing date: 1982-09-16
Publication date: 1984-04-11
Also published as: GB2127345B

Abstract

A vacuum press having a load bed (3) and a gas impermeable diaphragm (8) pivotable between a raised, inoperative, position and a lowered, operative, position in which it overlies a workpiece (29) on the load bed, means (11,12,21,22,23) being provided for suspending the diaphragm (8) such that movement thereof between inoperative and operative positions is substantially linear in a direction generally orthoganal to the plane of the load bed as the diaphragm closely approaches the load bed. The frame (7) supporting the diaphragm (8) is attached to the lower ends of arms (21,22) extending downwardly from an arm (11) which is slidable relative to an arm (12) pivoted to an upright (20). <IMAGE>

Description

SPECIFICATION Improvements in or relating to vacuum presses This invention is concerned with improvements in or relating to vacuum presses.

Vacuum presses are employed, inter alia, in the bonding of laminated sheet materials where it is essential that a substantially uniform pressure should be exerted upon the several layers of the laminate in order to ensure that a uniform bond is obtained at the interfaces of the layers over the whole area of the laminate. Reduced pressure is then applied to a chamber of the vacuum press to draw down a gas impermeable diaphragm or cover onto the laminate under atmospheric pressure to allow the layers of the laminate to bond under pressures of approximately 51bs per square inch (0.4kg per square centimetre) or more. The laminate is positioned on a load bed of the press for a bonding operation.

Vacuum presses have found particular, although not exclusive, application in the bonding of a large laminated panel, as for example are used in the manufacture of caravans or mobile homes, where an outer skin and an inner decorative wall are bonded to a layer of acoustic and thermal insulating material.

In some vacuum presses, such as disclosed in British Patent Specifications Nos. 2,038,708 and 2,007,150 for example, the diaphragm or cover is hingedly or pivotally connected generally to one edge of the bed of the press in order that it may be raised clear of the latter when a workpiece is to be removed and/or another workpiece loaded, thereby allowing ready access to the bed. As will be appreciated, the plurality of layers of a laminate when freshly loaded into a press are separated by wet, uncured adhesive which means that relative movement between the layers can readily occur. Such movement, especially between the first two layers but sometimes involving other layers, often takes place when the diaphragm is moved from its raised, inoperative position to its lowered, operative position about its hinge or pivot axis.This is because the diaphragm progressively contacts the upper layer of the workpiece, starting at the edge nearest the hinge or pivot axis, with the result that the upper layer tends to be slid or dragged relative to the layer or layers therebeneath.

It is, of course, possible to pack the edges of the workpiece to prevent this sliding movement on lowering of the hinged diaphragm but this is time consuming and not always practicable. It is also possible to use presses having diaphragms which are not hinged and which are raised and lowered vertically but these are more complex in construction, and hence more expensive.

The object of the present invention is to provide a vacuum press having a hinged or pivoted diaphragm but which does not suffer from the problem of imparting relative movement between two or more layers of the workpiece when the diaphragm is lowered to the operative position.

According to the present invention a vacuum press comprises a load bed upon which one or more substantially planar workpieces can be loaded, a gas impermeable diaphragm pivotally mounted adjacent one side of the load bed and pivotable between a raised, inoperative position and a lowered, operative position, in which it contacts the adjacent face of the or each workpiece, and means for reducing pressure between the load bed and the diaphragm in order to draw the diaphragm down onto the or each work piece under a predetermined pressure, the di aphragm comprising a frame which supports a flexible, gas impermeable sheet, the frame being suspended from at least one pair of arms, the arms of the or each pair being slidably mounted one upon the other for relative longitudinal movement with the frame rigidly attached to the arm furthest from the load bed by at least one member, and with the arm nearest the load bed pivotally attached to bracket means associated with the load bed, a link being pivotally connected at one end of the bracket means and pivotally connected at the other end to said at least one member, the arrangement being such that when the diaphragm is pivoted from the raised, inoperative position to the lowered operative position, the arms of the or each pair of arms slide relative to one another with the result that the movement of the diaphragm as it closely approaches the load bed is substantially linear in a direction generally orthogonal to the plane of the load bed.

Thus the present invention enables the diaphragm to approach the load bed, and hence the or each workpiece located thereon, generally vertically throughout (assuming the load bed is horizontal), whereby the problem of the upper layer or layers of the or each workpiece being dragged relative to the remaining layers when the diaphragm is moved to the operative position is obviated.

Preferably the arms of the or each pair of arms are provided with means to promote relative sliding movement therebetween. Such means may comprise one or more rollers or pieces of material having a low coefficient of friction.

A vacuum press constructed in accordance with the present invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the press, Figure 2 is a side view of the press from the right-hand side of Figure 1, Figure 3 is a partial plan view of Figure 2 to a larger scale, and Figure 4 is a section on the line IV-IV of Figure 1 to a larger scale.

Referring to the drawings, the vacuum press comprises a load bed made up of a plurality of modules 1 each of which comprises a rectangular, apertured plate 3 having a downwardly-extending peripheral frame 4 to impart extra rigidity, and supported at each corner by a leg 5 having an adjustable foot. Generally overlying the load bed, and pivotally movable with respect thereto, is a so-called diaphragm 6 comprising a rectangular frame 7 supporting a sheet 8 of neoprene, the frame and sheet being dimensioned so as to overlap the load bed on all four sides when the diaphragm is in the operative position.

The diaphragm 6 is suspended from a plurality of pairs of arms 9, there being effectively two pairs of arms for each module 1, the pairs of arms other than the two extreme pairs being associated with two adjacent modules. Each pair of arms 9 comprises an upper arm 11 and a lower arm 12 slidably mounted one upon the other for relative longitudinal movement by rollers 13 preferably formed from synthetic plastics material. Each arm 11,12 is of box section and is apertured at 14 (Figure 4) to enable the insertion of a roller 13 which is rotatably supported on a pin 15 extending through the arm and retained by split pins 16. Each roller 13 extends proud of the associated arm 11,12 through the corresponding aperture 14, so as to make rolling contact with the other arm.The arms 11,12 of each pair are thus slightly spaced apart as shown in Figure 4 although the spacing is not illustrated in Figure 2. The upper arm 11 of each pair 11,12 is fitted with two rollers 14 and the lower arm 12 with one roller although other roller arrangements may be employed. Each upper arm 11 is provided with a pair of opposed guides 17 which prevent the arms becoming misaligned, especially when undergoing relative sliding movement.

The rear end of each lower arm 12 is pivotally attached by a pivot pin or shaft 18 to a pair of upright members 19 of a bracket 20 attached to the rear of the associated module 1. The upper arm 11 of each pair 11,12 has rigidly attached thereto two pairs of downwardly extending arms 21,22 which are connected at their lower ends to the diaphragm frame 7.

The rearmost pair of arms 22 are connected to respective upright members 19 of the bracket 20 by links 23 which are pivotally attached to the respective components by pins 24,25, and the arms 22 carry rollers 26 which engage the underside of the associated arm 12.

The diaphragm 6 is thus pivotally mounted with respect to the load bed and is movable between a raised, inoperative position (shown in broken lines in Figure 2) and a lowered, operative position (shown in full lines in Figure 2) This movement is effected by a pneumatic actuator 27 fitted between a further upright member 28 of each bracket 20 and the associated lower arm 12.

It should be noted that Figure 1 shows the provision of a safety mechanism in the form of rods 31 suspended from pivoted arms 32, the rods extending around and below the diaphragm frame 7 so that should they encounter an obstruction as the diaphragm 6 is being lowered, the arms are pivoted which results in the press being rendered inoperative. This safety mechanism has been omitted from Figure 2.

In use of the vacuum press the diaphragm 6 is first raised to the inoperative position by extending the actuators 27 and then a workpiece 29, or a plurality thereof, loaded onto the load bed. Each workpiece typically comprises a mutli-layer laminate with the layers separated by wet or uncured adhesive. The diaphragm 6 is then pivioted to the operative position by contracting the actuators 27. During this pivotal movement of the diaphragm 6, and hence the pairs of arms 11,12, the upper arms 11 slide relative to the respective arms 12 (to the left as seen in Figure 2) by virtue of the upper arms being tied to the bracket members 19 through the intermediary of the arms 22 and links 23.As a result, the locus 33 of the movement of the rear edge of the diaphragm 6 (that nearest to the workpiece 29 at the commencement of the downward pivotal movement of the diaphragm) is substantially linear and orthogonal to the plane of the load bed, i.e. substantially vertical. This is in contrast with the arcuate locus 34 which would pertain if the diaphragm were pivotally mounted in the conventional manner. Thus the diaphragm 6 approaches the workpiece 29 generally vertically over the entire area so that any dragging of the upper or lower layers of the or each workpiece 29 relative to the remaining layers is obviated. The locus of the movement of the front edge of the diaphragm 6 is indicated at 35.

Thus the diaphragm 6 does not first contact the workpiece 26 along one edge so as to impart a sliding movement to the top layer or layers thereof.

Instead, the diaphragm 6 contacts the workpiece generally uniformly over the entire area thereof.

With the diaphragm in the operative position, vacuum is applied to the workpiece 29, by a vacuum pump which has an inlet provided below the load bed of the machine, via the apertures in the plates 3.

Of course, below the load bed means are provided (not shown) for sealing the interior of the press from the exterior. The vacuum draws the sheet 8 down onto the workpiece, whereby a prederermined pressure is applied to the latter whilst the adhesive between the layers cures. After application of the vacuum, the diaphragm 6 is released by bleeding air into the interior of the press until atmospheric pressure is reached therein at which time the press can be opened by raising the diaphragm and the workpiece extracted and another loaded. Operation of the press can be fully automated.

The extremely effective solution to the problem of dragging afforded by the present invention is achieved by a relatively simple modification to the known construction, namely the provision of a pair of relatively movable arms in place of a single arm, and the provision of a link between the diaphragm support structure and the load bed.

As already mentioned, the arrangement of the rollers 13 shown in the drawings can be varied and indeed, the rollers may be replaced by alternative anti-friction means such pieces of low coefficient of friction material disposed at the interface of the two arms 11,12.

CLAIMS (Filed on 7 Sept. 83.) 1. Avacuum press comprising a load bed upon which one or more substantially planar workpieces can be loaded, a gas impermeable diaphragm pivotally mounted adjacent one side of the load bed and pivotable between a raised, inoperative, position and a lowered, operative, position in which it contacts the adjacent face of the or each workpiece, and means for reducing pressure between the load bed and the diaphragm in order to draw the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. load bed on all four sides when the diaphragm is in the operative position. The diaphragm 6 is suspended from a plurality of pairs of arms 9, there being effectively two pairs of arms for each module 1, the pairs of arms other than the two extreme pairs being associated with two adjacent modules. Each pair of arms 9 comprises an upper arm 11 and a lower arm 12 slidably mounted one upon the other for relative longitudinal movement by rollers 13 preferably formed from synthetic plastics material. Each arm 11,12 is of box section and is apertured at 14 (Figure 4) to enable the insertion of a roller 13 which is rotatably supported on a pin 15 extending through the arm and retained by split pins 16. Each roller 13 extends proud of the associated arm 11,12 through the corresponding aperture 14, so as to make rolling contact with the other arm.The arms 11,12 of each pair are thus slightly spaced apart as shown in Figure 4 although the spacing is not illustrated in Figure 2. The upper arm 11 of each pair 11,12 is fitted with two rollers 14 and the lower arm 12 with one roller although other roller arrangements may be employed. Each upper arm 11 is provided with a pair of opposed guides 17 which prevent the arms becoming misaligned, especially when undergoing relative sliding movement. The rear end of each lower arm 12 is pivotally attached by a pivot pin or shaft 18 to a pair of upright members 19 of a bracket 20 attached to the rear of the associated module 1. The upper arm 11 of each pair 11,12 has rigidly attached thereto two pairs of downwardly extending arms 21,22 which are connected at their lower ends to the diaphragm frame 7. The rearmost pair of arms 22 are connected to respective upright members 19 of the bracket 20 by links 23 which are pivotally attached to the respective components by pins 24,25, and the arms 22 carry rollers 26 which engage the underside of the associated arm 12. The diaphragm 6 is thus pivotally mounted with respect to the load bed and is movable between a raised, inoperative position (shown in broken lines in Figure 2) and a lowered, operative position (shown in full lines in Figure 2) This movement is effected by a pneumatic actuator 27 fitted between a further upright member 28 of each bracket 20 and the associated lower arm 12. It should be noted that Figure 1 shows the provision of a safety mechanism in the form of rods 31 suspended from pivoted arms 32, the rods extending around and below the diaphragm frame 7 so that should they encounter an obstruction as the diaphragm 6 is being lowered, the arms are pivoted which results in the press being rendered inoperative. This safety mechanism has been omitted from Figure 2. In use of the vacuum press the diaphragm 6 is first raised to the inoperative position by extending the actuators 27 and then a workpiece 29, or a plurality thereof, loaded onto the load bed. Each workpiece typically comprises a mutli-layer laminate with the layers separated by wet or uncured adhesive. The diaphragm 6 is then pivioted to the operative position by contracting the actuators 27. During this pivotal movement of the diaphragm 6, and hence the pairs of arms 11,12, the upper arms 11 slide relative to the respective arms 12 (to the left as seen in Figure 2) by virtue of the upper arms being tied to the bracket members 19 through the intermediary of the arms 22 and links 23.As a result, the locus 33 of the movement of the rear edge of the diaphragm 6 (that nearest to the workpiece 29 at the commencement of the downward pivotal movement of the diaphragm) is substantially linear and orthogonal to the plane of the load bed, i.e. substantially vertical. This is in contrast with the arcuate locus 34 which would pertain if the diaphragm were pivotally mounted in the conventional manner. Thus the diaphragm 6 approaches the workpiece 29 generally vertically over the entire area so that any dragging of the upper or lower layers of the or each workpiece 29 relative to the remaining layers is obviated. The locus of the movement of the front edge of the diaphragm 6 is indicated at 35. Thus the diaphragm 6 does not first contact the workpiece 26 along one edge so as to impart a sliding movement to the top layer or layers thereof. Instead, the diaphragm 6 contacts the workpiece generally uniformly over the entire area thereof. With the diaphragm in the operative position, vacuum is applied to the workpiece 29, by a vacuum pump which has an inlet provided below the load bed of the machine, via the apertures in the plates 3. Of course, below the load bed means are provided (not shown) for sealing the interior of the press from the exterior. The vacuum draws the sheet 8 down onto the workpiece, whereby a prederermined pressure is applied to the latter whilst the adhesive between the layers cures. After application of the vacuum, the diaphragm 6 is released by bleeding air into the interior of the press until atmospheric pressure is reached therein at which time the press can be opened by raising the diaphragm and the workpiece extracted and another loaded. Operation of the press can be fully automated. The extremely effective solution to the problem of dragging afforded by the present invention is achieved by a relatively simple modification to the known construction, namely the provision of a pair of relatively movable arms in place of a single arm, and the provision of a link between the diaphragm support structure and the load bed. As already mentioned, the arrangement of the rollers 13 shown in the drawings can be varied and indeed, the rollers may be replaced by alternative anti-friction means such pieces of low coefficient of friction material disposed at the interface of the two arms 11,12. CLAIMS (Filed on 7 Sept. 83.)

1. Avacuum press comprising a load bed upon which one or more substantially planar workpieces can be loaded, a gas impermeable diaphragm pivotally mounted adjacent one side of the load bed and pivotable between a raised, inoperative, position and a lowered, operative, position in which it contacts the adjacent face of the or each workpiece, and means for reducing pressure between the load bed and the diaphragm in order to draw the

diaphragm down onto the or each workpiece under a predetermined pressure, the diaphragm comprising a frame which supports a flexible, gas impermeable sheet, the frame being suspended from at least one pair of arms, the arms of the or each pair being slidably mounted one upon the other for relative longitudinal movement with the frame rigidly attached to the arm furthest from the load bed by at least one member, and with the arm nearest the load bed pivotally attached to bracket means associated with the load bed, a link being pivotally connected at one end of the bracket means and pivotally connected at the other end to said at least one member, the arrangement being such that when the diaphragm is pivoted from the raised, inoperative, position to the lowered, operative, position, the arms of the or each pair of arms slide relative to one another with the result that the movement of the diaphragm as it closely approaches the load bed is substantially linear in a direction generally orthogonal to the plane of the load bed.

2. A vacuum press according to claim 1, wherein the or each pair of arms has anti-friction means disposed therebetween to promote relative sliding movement of the arms.

3. A vacuum press according to claim 2, wherein the anti-friction means comprise at least one roller.

4. A vacuum press according to claim 3, wherein each arm of the or each pair of arms is of box section and has at least one roller mounted therewithin such that it extends proud of the associated arm for rolling engagement with the other arm of the pair.

5. A vacuum press according to claim 2, wherein the anti-friction means comprise one or more pieces of material having a low coefficient of friction.

6. A vacuum press according to any of the preceeding claims, wherein guide means are provided on the or each pair of arms to prevent misalignment of the arms during relative sliding movement thereof.

7. A vacuum press according to any of the preceeding claims, wherein one end of each lower arm of the or each pair of arms is pivotally attached by a pivot shaft to a pair of generally upright members of bracket means attached to the rear of the load bed.

8. A vacuum press according to any of the preceding claims, wherein the upper arm of the or each pair of arms has one end of each of two further arms attached at or towards respective ends thereof, with the other ends of the further arms being attached to the frame of the diaphragm to support the latter.

9. A vacuum press according to claim 8, wherein the further arm at one end of the upper arm is attached to the load bed via links pivotally attached to the load bed and to said further arm.

10. A vacuum press according to claim 8 or 9, wherein the further arm at said one end of the upper arm carries a roller which engages the underside of the lower arm.

11. A vacuum press substantially as herein particularly described with reference to the accompanying drawings.