WO2004020740A1

WO2004020740A1 - Moulding apparatus

Info

Publication number: WO2004020740A1
Application number: PCT/GB2003/003693
Authority: WO
Inventors: Martin Waller
Original assignee: Vernacare Limited (Formerly Called Verna Limited)
Priority date: 2002-08-29
Filing date: 2003-08-26
Publication date: 2004-03-11
Also published as: AU2003260737A1; GB0220034D0; GB2392409A

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.

Description

DESCRIPTION

MOULDING APPARATUS

The present invention relates to moulding apparatus and in particular, but not

exclusively, to apparatus for moulding articles from 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 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 of the 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 fluid-permeable

moulding surface mounted on the housing and defining the shape 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.

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

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.

The present invention also includes an apparatus for forming an article from

a fibrous slurry, comprising one or more moulds in accordance with the invention.

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. 1 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.

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 10 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, defined 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

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 of time 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 high-pressure 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

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

- 1 - CLAIMS

1. A mould for forming an article from a fibrous slurry comprising a housing,

a fluid-permeable moulding surface mounted on the housing and defining the shape

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.

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 1 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.

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.

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

portions.

10. An apparatus for forming an article from fibrous slurry, comprising one

or more moulds as claimed in any of the preceding claims.