GB2392409A

GB2392409A - Moulding apparatus

Info

Publication number: GB2392409A
Application number: GB0220034A
Authority: GB
Inventors: Martin Waller
Original assignee: VERNA Ltd
Current assignee: VERNA Ltd
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2004-03-03
Also published as: AU2003260737A1; GB0220034D0; WO2004020740A1

Abstract

A mould (10) for forming articles from a fibrous slurry (e.g. a paper pulp slurry has a housing (22) a moulding surface (26) (e.g. of metal mesh) defining the shape of the article to be formed and which is supported by a rigid part (24) of the housing and a chamber (34) defined between the fluid permeable member and the housing. The chamber has a removably attachable portion (28) which allows access to the chamber and to the reverse face of the moulding surface (26) to facilitate cleaning. The mould comprises two halves which may be hinged together along one edge.

Description

DESCRIPTION

MOULDING APPARATUS

The present invention relates to moulding apparatus and in particular, but not exclusively, to apparatus for moulding articles frond paper pulp.

It is known to form hollow articles such as disposable urine bottles, bed pans, bowls and the like from paper pulp by introducing paper pulp into a mould having a water-permeable moulding surface (e.g. made from metal gauze) formed into the shape of the article to be produced. A vacuum is applied to the rear face of the moulding surface which draws the paper pulp onto the front surface. The vacuum draws much of the water through the moulding surface, causing solid material to build up on the moulding surface in the desired shape. The mould is then opened to allow removal of the moulded article which is thereafter dried, for example in an oven. An example of such a mould, incorporated into an apparatus for continuously vacuum forming articles, is disclosed in GB-A-2153740.

In order for the apparatus to function efficiently, it is necessary for the moulding surfaces to be cleaned periodically. This is necessary since deposits can build up on the moulding surface and also in the chamber on the opposite side of the moulding surface to which vacuum is applied. Such deposits can result in uneven application of vacuum over the moulding surface, which can result in malformation of the moulded articles.

For the moulds described in GB-A-2153740, the moulds are cleaned by applying high-pressure water jets to the moulding surface with the aim of flushing

r away unwanted deposits. However, this is not always entirely successful since the application of high-pressure water jets to the moulding surface can still leave deposits on the opposite face of the moulding surface. Moreover, this technique is not particularly successful in removing deposits from the vacuum chamber since the power of the jets is greatly diminished after passing through the moulding surface and thus removal of unwanted deposits from the vacuum chamber is achieved mainly by the flushing effect of water passing through the vacuum chamber.

It is an object ofthe present invention to overcome or alleviate such problems.

In accordance with the present invention, there is provided a mould for forming an article from a fibrous slurry comprising a housing, a fluidpermeable moulding surface which defines the shape of the article to moulded and a chamber between the fluid permeable member and the housing, the chamber comprising a removably attachable portion which allows access to the chamber.

The removable portion of the mould housing allows access to the mould chamber and to the reverse face of the moulding surface, which facilitates removal of unwanted deposits from the mould chamber and from the reverse face of the moulding surface.

In one embodiment, the removably attachable portion is provided with a port for application of a vacuum. The port may be conveniently located centrally on the removably attachable portion, to provide a more uniform application of vacuum.

Preferably, the removably attachable portion comprises a plate member.

Preferably, the fluid-permeable moulding surface is supported on a rigid

- 3 member, e.g. a plate member having through apertures which communicate with the chamber. The moulding surface preferably comprises metal mesh.

The mould may comprise a plurality of mould portions which are relatively movable (e.g. hingeable) from a closed position, which defines the shape of the article to be formed, to an open position, which allows removal of a formed article.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawing, in which: Fig. I is a perspective view of an embodiment of mould in accordance with the present invention; and Fig. 2 is a partially exploded perspective view of the mould of Fig. 1.

The mould 10 illustrated in Figs. 1 and 2 is formed from two mould parts, 12, 14. Each mould part is provided with a respective pair of apertured lugs 16, 18 which receive a hinge pin 20 by means of which the two mould parts 12, 14 are hingedly connected. The mould illustrated in Figs. 1 and 2 is shown in the open position but when the two mould parts 12, 14 are hinged to the closed position their inner surfaces define the shape of an article to be formed.

With reference to Fig. 2, each mould half 12, 14 comprises a mould housing 22 and a drilled base 24 of generally of the same shape of the article to be formed.

A stainless steel mesh 26 is in contact with, and is supported by the base 24 and accurately defines the shape of the article to be formed, in this case a male urine bottle. The stainless steel mesh 26 is held in place by a retaining plate 27 which sandwiches the periphery of the mesh between the retaining plate and the base 24.

- 4 The rear of each mould half 12, 14 is closed off by a closure plate 28 which is removably attached to the remainder of the housing by means of six screws 30, each of which is received in a correspondingly threaded aperture 32 in the periphery of the housing of the mould half. When the plate is secured in position on the housing, a vacuum chamber 34 is defined between the housing and the base plate and vacuum may be applied to the vacuum chamber by means of a vacuum port 36 extending from the closure plate. The vacuum port 36 is located midway between the two lateral edges of the closure plate in order to allow the application of a more uniform vacuum to the vacuum chamber 34.

In use, the closure plate is secured to the housing as shown in Fig. 1.

Typically, a plurality of moulds 10 will be provided as part of a moulding apparatus.

In particular, and as disclosed in GB-A-2153740, the mould l O may be provided in a series of banks of moulds which are indexed stepwise through the moulding procedure and which also opens and closes the moulds at the appropriate times in the cycle. In any case, in order to mould an article the two mould parts 12, 14 are hinged shut and the open aperture 38 of the moulds, deemed by two semi-cylindrical apertures 38a, 38b in the mould halves, is submerged in a slurry of paper pulp.

Vacuum is applied to the two vacuum ports on the two mould parts 12, 14, which causes the slurry to be drawn onto the metal gauze forming the moulding surface.

The continued application of vacuum causes the pulp solids to be deposited on the moulding surface and for water to be withdrawn from the two mould parts via the

/ - - 5 vacuum ports. Once sufficient time has elapsed for the desired thickness of pulp to be deposited, the mould is removed from the paper pulp slurry but vacuum is still applied to the two mould parts thereby removing additional water from the pulp solids deposited on the moulding surfaces. Once sufficient water has been removed for the article to be handled without damaging it, the mould is opened and the article is removed, preferably on to a demoulding pin as disclosed in GB-A-2153740.

As mentioned previously, after a period oftime the base plate and the vacuum chamber are likely to become clogged up with unwanted solids. Whilst the moulding surface can be adequately cleaned by means of highpressure water jets, such jets are ineffective to clean the base plate and the vacuum chamber.

However, by unscrewing the retaining screws 30, the closure plate 28 may be removed, which allows access to the base 24 and to the vacuum chamber 34, which will then be cleared of unwanted deposits, for example by use of a high-pressure water jet. Once cleaning has taken place 28 the closure plate may be reattached by means of the six retaining screws 30.

The invention is not restricted to the details of the aforegoing embodiment.

For example, although the embodiment refers to a two-part mould, the mould may be one-part mould or may have more than two parts. However, it is preferable for the housing of each mould part to be provided with a removable portion which allows access to the vacuum chamber and to the base plate therein.

Moreover, although the embodiment described relates to vacuum formation, it is equally applicable to pressure formation of articles from paper pulp, in which

( ' - 6 instead of applying a vacuum to the reverse face of the moulding surface, positive pressure is applied to the interior of the mould volume, which forces water through the gauze and deposits solids on the gauze.

Claims

--c Am- If: - 7 CLAIMS

1. A mould for forming an article from a fibrous slurry comprising a housing, a fluid-permeable moulding surface which defines the shape of the article to moulded and a chamber between the fluid permeable member and the housing, the chamber comprising a removably attachable portion which allows access to the chamber.

2. A mould as claimed in claim 1, wherein the removably attachable portion is provided with a port for application of vacuum.

3. A mould as claimed in claim 2, wherein the port is located centrally on the removably attachable portion.

4. A mould as claimed in any of claims I to 3, wherein the removably attachable portion comprises a plate member.

5. A mould as claimed in any of the preceding claims, wherein the fluid-

permeable moulding surface is supported on a rigid member.

6. A mould as claimed in claim 5, wherein the rigid member comprises a plate member having through apertures which communicate with the chamber.

7. A mould as claimed in any of the preceding claims, wherein the moulding surface comprises metal mesh.

20

8. A mould as claimed in any of the preceding claims, comprising a plurality of mould portions which are relatively movable from a closed position, which defines the shape of the article to be formed, to an open position, which allows removal of a formed article.

lO

9. A mould as claimed in claim 8, comprising a plurality of hinged mould portions.

1 O. An apparatus for forming an article from fibrous slurry, comprising one or more moulds as claimed in any of the preceding claims.

5

11. An apparatus for forming an article from fibrous slurry, substantially as herein described with reference to, and as illustrated in, the accompanying drawings.

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9. A mould as claimed in claim 8, comprising a plurality of hinged mould

- 8 portions. I 0. A mould for forming an article from fibrous slurry, substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.

Amendments to the claims have been filed as follows q 1. A mould for forming an article from a fibrous slurry comprising a housing, a fluidpermeable moulding surface mounted on the housing and defining the shape 5 of the article to moulded and a chamber between the fluid permeable member and the housing, the housing comprising a removably attachable portion which allows access to the chamber with the moulding surface mounted on the housing.

10 3. A mould as claimed in claim 2, wherein the port is located centrally on the removably attachable portion.

4. A mould as claimed in any of claims 1 to 3, wherein the removably attachable portion comprises a plate member.

S. A mould as claimed in any of the preceding claims, wherein the fluid 15 permeable moulding surface is supported on a rigid member.

6. A mould as claimed in claim S. wherein the rigid member comprises a plate member having through apertures which communicate with the chamber.