EQUIPMENT FOR MAKING ARTICLES FROM PULP MATERIAL. AND SUCTION MOULD FOR USE IN SUCH EQUIPMENT
TECHNICAL FIELD The present invention relates to equipment of the kind set forth in the preamble of claim 1.
BACKGROUND ART
In equipment of this kind, the suction moulds are costly to produce, especially if they are to comprise a great number of projections or raised portions, as the sha¬ ping surface is produced by material-removing machining of a metallic blank, the shaping surface of which is formed by a through-going metal gauze having been shaped in its en- tirety. Such suction moulds can only be used profitably for making extremely great numbers of uniform products, such as e.g. egg trays or egg packages.
Recently, the need has arisen for also being able to make smaller series of articles, e.g. thin-walled papier- -mache products of pulp material with raised portions or projections to be used as shock-absorbing filling bodies instead of moulded filling bodies of rigid porous plastic material between an external packaging means, e.g. a cor¬ rugated-paper box, and an article packaged therein, such as an electronic apparatus, a kitchen machine etc., said pro¬ jections or raised portions necessarily having various shapes and sizes and being located in a manner corresponding to the article to be packaged.
DISCLOSURE OF THE INVENTION
On the above background, it is the object of the present invention to provide equipment of the kind referred to initially, with which it is possible to fill the need mentioned above, and which can be produced at such low cost, that it makes it possible in a profitable manner to produce limited numbers of thin-walled or shell-shaped products of
pulp material.
This object is achieved with equipment, according to the present invention being characterized by the features set forth in the characterizing clause of claim 1. With this arrangement, it is possible to assemble a suction mould with the desired raised portions or projections from a small number of standardized and series-produced com¬ ponents, which may in certain cases be used again, so that the suction mould can be produced at substantially reduced cost.
The invention also relates to a suction mould to be used in equipment according to the invention. A preferred embodiment for such a suction mould is set forth in claim 2.
Another embodiment of the suction mould according to the invention is set forth in claim 3. The use of stainless steel makes the components concerned easy to clean and pro¬ tects them against electrolytic corrosion. The combination set forth in items b and c has proved suitable for achieving a homogenous deposition of pulp material on the shaping sur- face of the suction mould.
A further preferred embodiment is set forth in claim 4. Especially high-density polyethylene is cheap and easy to shape at low cost to the desired shapes, while its hy- drophobic surface properties reduce the necessary cleaning of the suction mould.
Yet another preferred embodiment is set forth in claim 5. A wire-gauze covering made in the manner indicated has proved to serve its purpose excellently, and the resi¬ stance welding of the wire gauze has proved not to reduce its permeability.
With a view to easy separation of papier-mache pro¬ ducts made with a suction mould according to the invention and having them stacked on top of each other, the suction mould may also exhibit the features set forth in claim 6. With this arrangement, a protruding rib will be formed be¬ tween the ribs referred to on the side of the papier-mache
product facing the suction mould, while on the opposite side of the product a projection with a relatively plane surface will be formed, said projection, when dried papier-mache products are stacked on top of each other and nested within each other, will abut against the protruding rib on the papier-mache product lying immediately above, thus producing a certain spacing from the latter.
When the suction mould has been separated from the shell of pulp material having been aspirated onto it and this shell has been placed in the drying section of the equipment and dried so as to form a papier-mache product, in which process a certain drying shrinkage occurs depending on the production parameters, it is often preferred to hot- -press the papier-mache product, giving the latter a more dense consistency and a more smooth and an esthetically pleasing surface.
For this reason, the present invention also relates to equipment of the kind set forth in the preamble of claim 7, and according to the invention, this equipment is charac- terized by the features set forth in the c a act rizing clause of said claim 7. with this arrangement it is possible to exploit the benefits of the modular-system arrangement set forth in claim 1 and used for making the suction mould.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following detailed portion of the present specification, the present invention will be explained in more detail with reference to the drawings, in which
Figure 1 is a partial plan view of the corner of a suction mould according to the invention,
Figure 2 is a sectional view along the line A-A in Figure 1,
Figure 3 is a sectional view along the line A-B in Figure 1, and Figure 4 is a partial sectional view through a region of a pressing mould according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figures 1-3 show a corner of a suction mould generally designated 1. The suction mould 1 comprises a plane metal plate 2, along the periphery of which a so-called flushing edge 3 is secured by means of screws 4. The metal plate 2 is perforated by a number of through-going bores 5, prefer¬ ably with a diameter of 2 mm and having their centres spaced from each other by appr. 8 mm, the moulding surface of said metal sheet 2 being covered by 50-mesh metal wire gauze 6. Both the metal plate 2 and the metal wire gauze 6 are made of stainless steel. Projections generally designated 8 are secured to the metal plate 2 above suitable openings 7, each of said projections consisting of a hollow member 9 of high-density polyethylene, the external surface of which is covered with metal-wire gauze 10. The hollow members 9 are perforated by bores 11, like the bores 5 in the plate 2 having a diameter of 2 mm and preferably having their centres spaced approximately 8 mm apart. Like the metal-wire gauze 6 in the plate 2, the metal-wire gauze 10 is made from stain- less steel and has a mesh size of 50. As shown in Figure 3, the projections 8 are secured to the metal plate 2 by means of screws 12.
The projections 8 shown in the drawing all have the same dimensions and the same shape, as they are shaped some- what like truncated cones with square base and rounded cor¬ ners. It is, however, to be understood that according to the present invention, the projections 8 may have various dimensions and shapes, such as similar to a truncated cone with a rectangular base and rounded corners, and they may have been selected among a modular system comprising pre- -fabricated projections of a relatively small number of types with different dimensions and shapes.
In the corner of suction mould 1 shown in Figure 1, a pair of ribs 13 are placed close side-by-side between two of the projections 8. The purpose of these ribs 13 is to produce a recess with a downwardly protruding rib on the
surface shaped by the suction mould 1 on the papier-mSche product made on this mould, and to produce a substantially plane raised portion on the opposite surface of the product, said rib and a corresponding raised portion on the next product lying below in a stack of nested papier-mSche pro¬ ducts having as their purpose to make it easier to separate stacked products from each other.
Figure 4 is a partial sectional view of a region of a pressing mould according to the present invention, adapted for hot-pressing of a dried papier-mache product made with a suction mould according to the invention.
The pressing mould consists of a first mould part generally designated 14 and a second mould part generally designated 15. The first mould part 14 comprises projections 16 of a shape complementary to the shape of the recesses produced in the dried papier-mache product by the shaping surface of the suction mould, while the second mould part
15 comprises recesses 17 of a shape complementary to the shape of the projections 16 on the first mould part, but having dimensions greater than the projections 16 on the first mould part enlarged by the wall thickness of the hot- -pressed papier-mSche product. Both the projections 16 and the recesses 17 may be produced by suitably machining metal¬ lic work pieces. The projection 16 shown in Figure 4 is pre-fabricated and chosen from second modular system comprising a relatively small number of types with different dimensions and shapes corresponding to the dimensions and shapes after shrinkage of the recesses produced in the papier-mSchέ product using projections according to the first-mentioned modular system described in connection with the suction mould related to with reference to Figures 1-3.
In the exemplary embodiment shown, the projections
16 on the first mould part 14 are secured to a substantially plane metal plate 18 by means of screws 19.
LIST OF PARTS
10
15
20