WO1997004945A1

WO1997004945A1 - Membrane press with self-supporting base and closure

Info

Publication number: WO1997004945A1
Application number: PCT/AU1996/000490
Authority: WO
Inventors: Ross George Payne
Original assignee: Pay Co Products Pty. Ltd.
Priority date: 1995-08-02
Filing date: 1996-08-02
Publication date: 1997-02-13

Abstract

A membrane press comprising a closure (12) and a base (14), said base (14) being configured, provide an interior which is able to support a substrate (64) to which a membrane (66) is to be applied, the closure (12) being movable between a closed position over the base (14) at which it defines a closed sealed space between the closure and the base and an open position clear of the base (14) to provide access to the interior of the base (14), whereby when in the closed position the membrane (66) is supported between the closure (12) and the base (14) to define separate spaces above and below the membrane (66), said press further comprising a means (44, 48, 52) to heat the membrane and to create a pressure differential to each side of the membrane (66), said base (14) and closure (12) having sufficient structural strength to be self-supporting against the pressure differential created between the space and the exterior when in use, and locking means (22, 26, 32) provided at spaced intervals around the junction between the closure and base to lockingly retain the closure (12) in the closed position.

Description

MEMBRANE PRESS WITH SELF-SUPPORTING BASE AND CLOSURE

The present invention relates to a membrane press.

More particularly, the membrane press of the present invention is intended for use in applying a membrane to a substrate. A particular example of the form of membrane with which the press can be used is formed of a flexible thermoplastics material which will soften when heated.

Membrane presses of the form to which the invention relates are used in the application of decorative coatings in the form of a membrane to work pieces. The presses generally comprise a chamber which comprises a base and a closure which cooperates with the base and serves to sealingly close the chamber. The work pieces which can comprise a panels such, as door panels, are located on the base with the closure open and a membrane is sealingly received across the base above the work piece. The chamber is then closed. The chamber is provided with a heating means which serves to heat and thus soften the membrane, The chamber is also provided with a pressurisation means and the subsequent to the softening of the membrane a differential pressure is created within the chamber to each side of the membrane to cause it to be forced against the work piece to be in close intimate contact with the work piece. Prior to the location of the work pieces within the chamber they are coated with an adhesive or alternatively the underside of the membrane is provided with a pressure sensitive adhesive whereby on the membrane being forced onto the work piece it is adhered thereto.

Such presses generally generate significant differential pressures and in order to provide support for the base with closure in position it has been usual practice to locate the base and closure located within a press frame which serves to support the structure during the application of the pressure within the chamber. The press frame of such prior art presses usually also has a lifting means for the closure and a locating system for the base where the base is typically movable from a position removed from the closure to a position underneath the closure.

This is generally achieved by the base being arranged in a laterally slidable manner. The lifting means for the closure is usually a hydraulic press which holds the closure in position on the base whilst a differential pressure is applied to the membrane as described above. In the past the hydraulic press has needed to be very powerful, in order to hold to closure onto the base and in order to resist the pressures created within the space. Such powerful hydraulic presses are expensive and bulky.

One object of the present invention is to avoid the need for the substantial outer press frame of the prior art presses. A further object is to avoid the necessity of the sliding base or any other tracking means therefor.

Accordingly, the present invention resides in a membrane press comprising an closure and a base, said base being configured provide an interior which is able to support a substrate to which a membrane is to be applied, the closure being movable between a closed position over the base at which it defines a closed sealed space between the closure and the base and an open position clear of the base to provide access to the interior of the base, whereby when in the closed position the membrane is supported between the closure and the base to define separate spaces above and below the membrane, said press further comprising a means to heat the membrane and to create a pressure differential to each side of the membrane, said base and closure having sufficient structural strength to be self supporting against the pressure differential created between the space and the exterior when in use, and locking means provided at spaced intervals around the junction between the closure and base to lockingly retain the closure in the closed position. According to a preferred feature of the present invention, the locking means comprises a plurality of apertured lugs provided on the closure or the base and a correspondingly located set of pawl members on the base or closure respectively and adapted to engage the apertures in the lugs when in the locking position. According to one particular embodiment the pawl members are supported to one side of a pair of apertured members which will receive the respective lug between them when the closure is in the closed position said pawls being slidably receivable through the apertures in the lug and members when the closure is in the closed position.

According to a preferred feature of the present invention, the closure is pivotally supported to one side of the base. According to a further preferred feature of the previous feature, the base is supported from a base structure and the closure is hingedly supported from the base structure.

According to an alternative preferred feature of the previous feature, the closure is pivotally supported from the base structure through a parallelogram linkage enabling the closure to be moved upwardly and laterally with respect to the base from the closed position to the open position.

In previously known presses the differential pressure to each side of the membrane has been effected by evacuating the side of the membrane adjacent the substrate. It has been found however that unless the substrate is porous or is formed with an array of apertures the surface of the substrate to which the membrane is to be applied carmot be very complex if the membrane is to closely conform to the configuration of the surface. In other arrangements a positive pressure is applied to the face of the membrane remote from the substrate. This positive pressure has been applied by an inflatable bag accommodated in the closure into which oil or air can be introduced. Again this arrangement is limited in regard to the complexity of the surface to which the membrane can be applied. According to a preferred feature of the present invention, the base is associated with an evacuation means for inducing a reduced pressure in the space and the closure is associated with a pressurising means for creating a positive pressure within the space when the closure is in the closed position.

In addition in the past, heating of the membrane has been achieved by introducing a heated medium into the closed space. This has included using heated air which has been blown directly into the space or into the inflatable bag referred to above in order to provide both heat and pressure. The difficulty with each of these arrangements has related to the limited control in regard to the degree of heating which is applied to the membrane and the thermal inertia of such a heating arrangement.

According to a further preferred feature of the present invention, the closure is provided with the means for heating the membrane. According to one particular embodiment the heating means comprises a set of radiant heater elements mounted at spaced intervals within the closure and located such that they are directed onto the membrane when the membrane is in position in the space. It is a preferred feature that the space within the closure is provided with temperature sensors.

In addition it has been found that in practice a considerable amount of time is lost in accurately locating the work pieces within the chamber before initiating the coating process.

It is a preferred object of the invention to provide a means which improves the efficiency of membrane presses of the form described above.

According to a preferred feature of the invention said base accommodates a support which extends across the base which is adapted to support one or more work pieces, said support being adapted to provide fluid flow to each side of the support when located within the space and said support being removable from the base.

The invention will be more fully understood in the light of the following description of several specific embodiments. The description is made with reference to the accompanying drawings, of which:-

Figure 1 is an upper perspective view of upper and lower trays of a membrane press according to the first embodiment of the present invention;

Figure 2 is an upper perspective view of the upper and lower trays of the first embodiment in the closed position;

Figure 3 is a schematic cross-sectional elevation of the first embodiment illustrating the ancillary components of the membrane press;

Figure 4 is an upper perspective view of the second embodiment showing the upper and lower trays in the open position;

Figure 5 is a schematic isometric view of the embodiment showing the closure in the open position;

Figure 6 is an exploded isometric view of the embodiment shown at Figure 1 ; and

Figure 7 is a schematic sectional view of the embodiment in the closed condition.

The first embodiment shown at Figures 1 , 2 and 3 comprises a membrane press 10 having a closure 12 which takes the form of an inverted upper tray and a base 14 which takes the form of an upright lower tray. The interior of the closure 12 defines an upper cavity (not shown) while the interior of the base 14 defines a lower cavity 16. The closure 12 and base 14 are pivotally interconnected by means of a parallelogram linkage provided at each end 34 of the press 10. Each linkage comprises two elongate members 36 pivotally connected at their ends to the trays 12 and 14, as shown in Figures 1 and 2. The linkages allow the closure to be moved between a closed position, at which it overlies the base and is in close engagement therewith as shown at Figures 2 and 3 and an open position, at which it is located to one side of the base as shown at Figure 1 and further ensures that the closure 12 remains parallel to the base 14 throughout such movement. The linkages are such that when the closure is in the closed position over the base the full weight of the closure is carried by the upper edge of the base. A seal which takes the form an O-ring seal 40 is provided around the upper edge of the base in order to sealing engage with the closure 12 when the closure is in the closed position in order to sealingly isolate the space defined within the press when the press is closed.

The base 14 is associated with a support frame 38 which is positioned to one side of the base such that it is able to receive and support the closure 12 when it is in the open position as shown in Figure 1. The upper surface of the support frame 38 which is intended to support the closure is raised with respect to the base 14 which serves to reduce the effort required to move the closure 12 between the open position to the closed position.

The closure 12 is capable of withstanding the forces which will be generated within the press when the press is in operation. To achieve this the closure is provided on its outer surface with a plurality of spaced reinforcing ribs 18 which extend both transversely and longitudinally over the upper face of the closure. The transverse ribs 18 which terminate at the longitudinal sides 20 of the tray 12 are provided with downwardly depending lugs 22 which extend below the lower edge of the closure. Each of the lugs 22 are provided at their lower end with an aperture 24. In addition the longitudinal sides 28 of the base 14 are provided with a plurality of channel members 26 which are in one to one correspondence with the lugs 22 and which are located such that when the closure 12 is in the closed position on the base 14, as shown in Figure 2, the lugs 22 are received between the flanges of the respective channel members 26. The flanges of the channel members 26 are each formed with an aperture 30 which is located such that it will be aligned with the aperture 24 of the respective lug 22 when the closure is in the closed position. In addition each channel member 26 is associated with a retractable locking pin 32 which is slidably supported and is aligned with the apertures 30 in the respective channel member 26. Each retractable locking pin 32 is operatively associated with a fluid operated cylinder which causes the locking pins to move into and out of engagement with the apertures in the respective channel members 26. The lugs 22, channel members 26, locking pins 32 and associated fluid operated cylinders jointly comprise the locking means of the first embodiment.

The interior of the closure 12 supports a plurality of radiant infra-red heater elements 42. As shown at Figure 3 the heater elements 42 are mounted to the underside of a baffle plate 44 which is supported within the closure 12 in a manner such that the heater elements are directed downwardly.

The upper wall of the closure is provided with an air inlet 46 which is in opposed relation to the baffle plate 44. The inlet 46 is in fluid connection with an air pressure tank 48 through a first fluid line 50 which has a valve 49 located therein.

The lower wall of the base 14 is provided with an air outlet 58 which is connected to the inlet of a suction pump or fan 52 through a further valve 54. The interior of the base 14 accommσdates a perforated floor 60 which is spaced above the lower wall which is intended to support a substrate support 62 upon which one or more panels 64 may be positioned within the base 62 where the panels comprise the substrate to which the membrane is to be applied.

In use when the press is in the open condition as shown at Figure 1 one or more panels are located on the substrate support 62 and a length of membrane 66 is laid over the base such that it is received over the upper edges of the base. The one or more panels 64 have an adhesive applied to their exposed surfaces which can be applied prior to them being placed in the base 14 or after they have been placed in the base 14. The closure 12 is at this time located in position on the support frame 38 allowing the user clear access to the interior of the base 14. The closure 12 is then moved to the closed position on the base 14 as shown at Figures 2 and 3 at which position the closure is fully supported by the upper edge of the base and the lugs 22 of the closure 12 are received within the respective channel members 26. The fluid operated cylinders are then activated to cause the locking pins 32 to engage with the apertures 24 and 30 in the respective lugs and channel members to lock the closure 12 and base 14 together. This action seals the closure 12 onto the base 14 and clampingly engages the membrane 66 therebetween.

The heater elements 42 are then activated to heat the membrane 66 and cause it to soften. The state of the membrane 66 is gauged by means of temperature sensors located in the upper space defined between the membrane 66 and the interior of the closure. On the membrane having been softened sufficiently the second valve 54 located in the fluid line 56 between the base 14 and the suction pump or fan 52 is then opened to create a negative pressure within the lower space defined between the interior of the base 14 and the membrane 66. In addition, at the same time or immediately subsequent to the creation of the negative pressure in the lower space, the upper space is pressurised by the opening of the first valve 49 provided in the fluid line 50 between the closure and the pressure tank 48 to create a positive pressure in that space. The resultant pressure differential to each side of the membrane forces the previously softened and now pliable membrane 66 onto the one or more panels 64 to cause it to closely conform to the contours of exposed surfaces of the one or more panels 64. At the conclusion of this process the closure 12 is moved to the open position as shown in Figure 1 , at which it is supported on the support frame 38 by being raised and moved transversely with respect to the base 14 from the closed position shown in Figure 2 through the parallelogram linkages 34 the open position thereby allowing the substrate 64 coated with the vinyl membrane 66 to be removed by the user. Before the coated substrate is removed the excess membrane to each side of the is cut away.

The manner in which the closure 12 and base 14 may readily opened and closed and locked together when in the closed position to be self supporting against the pressures generated within the press provides a compact membrane press 10. In addition the creation of a differential pressure to each side of the membrane by creating a positive pressure to one side and a negative pressure to the other side improves the effectiveness of the press without having to significantly increase the strength of the closure or base. As a result the press avoids the necessity of, a sliding or tracking lower tray in association with the base in order to move the substrate into and out of the pressing chamber, the high pressure hydraulics which has in the past been required to hold the closure in the closed position and the need for an outer frame capable of withstanding high pressure. Furthermore the application of positive and negative pressure to the respective faces of the substrate enable an intimate engagement between the membrane and the substrate. In addition the use of the radiant heater elements 42 provides a means of controlling the delivery of heat to the membrane far more accurately than has been available in the past.

The second embodiment of the invention as shown at Figure 4 comprises a press of similar form to the press of the first embodiment and as a result the same reference numerals are used in denoting corresponding elements to those of the first embodiment. The second embodiment differs from the first embodiment principally in that the closure 12 is pivotally supported to one side 100 of the base 14 . Pivotal movement of the closure 12 between the open and closed position is effected by a fluid operated cylinder or like means (not shown) which is accommodated within the base 14 and is connected to the closure through an articulated linkage (not shown). Since the closure is supported to one side of the base by the hinged connection the downwardly depending lugs 22, respective channel members 26, locking pins 32 and associated fluid operated cylinders need only be located along the side of the closure which is opposite the hinged connection.

As in the case of the first embodiment the closure 12 and base 14 have sufficient inherent strength to be able to withstand the pressures created within the press without the need for supplementary presses which have been necessary in previous apparatus. In addition when the closure is in the closed position it is principally supported by the upper edge of the base and as a result of the weight of the closure the closure will sealingly engage the base with the assistance of the seal (not shown) therebetween and also clampingly engage the membrane therebetween. As a result the press does not require the presence of an ancillary supportframe or hydraulic press to retain the closure in position over the base.

The third embodiment relates to a membrane press which is very similar to the second embodiment and corresponding reference numerals are used in Figures 5, 6 and 7 as those used in relation to the description of the first and second embodiments. As in the case of the previous embodiments the press of the third embodiment can be utilised to apply a membrane 66 to one or more panels 64 which can be accommodated within the press.

The press comprises a base 14 which is formed with a recess 16 on its upper face. One side of the base hingedly supports a closure 12 which is hingedly moveable between an open position as shown at Figure 5 and a closed position as shown at Figure 6 at which it fully encloses the recess 16 provided on the base 13. A suitable drive means is provided between the base 14 and the closure 12 in order to effect the movement of the closure between the open and closed position.

In addition a locking means corresponding to that of the second embodiment is provided along the side 28 of the base 14 which is opposite the edge of the base 14 which hingedly supports the closure 1. As in the case of previous embodiments the lower face of the closure 12 is formed with a second recess which is intended to cooperate with the first recess 16 provided in the base 14 when the closure is in the closed position to provide a chamber. The floor 60 of the first recess 14 is provided with a plurality of apertures which open into a plenum chamber (not shown) which is connected to a vacuum pump (not shown) while the second recess is connected to a source of pressurised fluid. In addition the second recess is provided with a plurality of infra-red heaters (not shown) as in the case of the previous embodiments.

The press further comprises a support tray 70 which is shaped such that it is receivable in the recess 16 in the upper surface of the base. The floor 71 of the support tray 70 is perforate and if desired may be formed of a suitable mesh material in order to provide for fluid communication to either side of the floor 71 of the support tray 70.

In use the press is associated with a source of membrane material (not shown) which is located to one side of the press whereby when the press is in the open position the membrane material can be extended over the upper face of the base 14 to fully enclose the first recess 16. When the closure 12 is then moved to the closed position the membrane is sealingly engaged between the opposed faces of the base 13 and the closure 16 to sealingly sub-divide the chamber into sub-chambers to each side of the membrane 11.

In use one or more work pieces 64 are located in the support tray 70 which is then positioned within the first recess 16 of the base 14. The membrane is then extended over the upper face of the base 14 and the closure 12 is moved to the closed position and is locked in that position with activation of the fluid operated cylinders associated with the locking means. The membrane is then heated as a result of the activation of the infra-red heaters until it has softened. On completion of the heating of the membrane, a reduced pressure is applied to the first recess 16 provided in the base 12 by activation of the vacuum pump while the sub-chamber between the membrane and the second recess is pressurised. The effect of this differential pressure to each side of the membrane causes it to be forced to close intimate contact with the work pieces 64. Prior to the application of the membrane a suitable adhesive is applied to the exposed surfaces of the work pieces 64 in the support tray 70. Altematively the face of the membrane 66 can be coated with a suitable pressure sensitive adhesive. Once the pressurisation has been completed the closure 12 can be then opened and the support tray 70 with the coated work pieces extracted from the recess provided in the base 14. As a result a second support tray 70 with a fresh set of work pieces 64 can be located in the base 14 while the first support tray is unloaded and fresh work pieces are located in that first support tray.

The third embodiment provides a means whereby the efficiency of utilisation of the membrane press can be significantly enhanced since the operation of the membrane press is not dependant upon the positioning of work pieces directly within the press and subsequent removal of the individual coated work pieces from the press.

If desired removable handles (not shown) may be associated with the support tray 70 where the handles can be engaged with the sides of the support tray to facilitate its transportation to and from the press and the positioning of the support tray within the base 14.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

Claims

The claims defining the invention are as follows:

1. A membrane press comprising a closure and a base, said base being configured provide an interior which is able to support a substrate to which a membrane is to be applied, the closure being movable between a closed position over the base at which it defines a closed sealed space between the closure and the base and an open position clear of the base to provide access to the interior of the base, whereby when in the closed position the membrane is supported between the closure and the base to define separate spaces above and below the membrane, said press further comprising a means to heat the membrane and to create a pressure differential to each side of the membrane, said base and closure having sufficient structural strength to be self supporting against the pressure differential created between the space and the exterior when in use, and locking means provided at spaced intervals around the junction between the closure and base to lockingly retain the closure in the closed position.

2. A membrane press as claimed at claim 1 wherein the locking means comprises a plurality of apertured lugs provided on the closure or the base and a correspondingly located set of pawl members on the base or closure respectively and adapted to engage the apertures in the lugs when in the locking position.

3. A membrane press as claimed at claim 2 wherein the pawl members are supported to one side of a pair of apertured members adapted to receive the respective lug between them when the closure is in the closed position, said pawls being slidably receivable through the apertures in the lug and members when the closure is in the closed position.

4. A membrane press as claimed at any one of claims 1 to 3 wherein the closure is pivotally supported to one side of the base.

5. A membrane press as claimed at any one of claims 1 to 3 wherein the closure is pivotally supported from the base structure through a parallelogram linkage enabling the closure to be moved upwardly and laterally with respect to the base between the closed position to the open position.

6. A membrane press as claimed at any one of the preceding claims wherein the closure is provided with the means for heating the membrane.

7. A membrane press as claimed at claim 6 wherein the heating means comprises a set of radiant heater elements mounted at spaced intervals within the closure and located such that they are directed onto the membrane when the membrane is in position in the space.

8. A membrane press as claimed at claim 6 or 7 wherein the space within the closure is provided with temperature sensors.

9. A membrane press as claimed at any one of the preceding claims wherein the base is associated with an evacuation means for inducing a reduced pressure in the space and the closure is associated with a pressurising means for creating a positive pressure within the space when the closure is in the closed position.

10.A membrane press as claimed at any one of the preceding claims wherein said base accommodates a support which extends across the base and which is adapted to support said substrate which comprises one or more work pieces, said support being adapted to provide fluid flow to each side of the support when located within the space and said support being removable from the base.

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

ET Rule 26