FR2667882A1 - PROCESS FOR MANUFACTURING PARTS COMBINED WITH PAPER PULP AND DEVICE FOR IMPLEMENTING IT. - Google Patents

Abstract

Process for the manufacture of articles from paper pulp, comprising: 1) a forming stage in which paper pulp is applied to a mould in the shape of the article, and 2) a stage of drying the previously deposited paper pulp, in which heat is applied to the article previously shaped in the mould. According to the invention, during the two stages the mould (1) is stationary and substantially horizontal, the lower part (3) of the mould pointing upwards. In addition, during the shaping stage an overpressure is maintained at room temperature on the outer side (5) of the mould in relation to the inside (3) of the mould (1). Finally, during the drying stage, a reduced pressure is maintained on the outer side (5) of the mould in relation to the inside (3) of the mould (1).

Description

i

  The present invention relates to a method for producing

  tion of shaped parts from pulp, and in particular paper pulp of the quality commonly called "noble pulp" in this industry, the material of these molded parts having substantially the same rigidity

than some cartons.

  The invention also relates to a device

  for the implementation of this method.

  This process makes it possible to manufacture, in particular, toys, sculptures, decorations of objects, display stands

  and / or packaging for cosmetics, perfumes, medi-

  products, as well as parts that can be used in jewelery, hygiene or

  arts in the form of packaging, boxes or even

advertising ports.

  Various devices are known for the manufacture of pulp articles

  In particular, US Pat. No. 1,697,244 which relates to

  formerly, relates to a machine for forming paper pulp comprising a wheel rotating about a horizontal axis and supporting at its periphery mold holders At the lower part of this wheel, is provided a container filled with pulp This machine comprises means for maintaining suction on the molds Thus, a constant and uniform pressure is maintained on the layer of

  pulp placed in the mold during the deposit of the paste

  The drying is carried out by the suction of hot air through the pulp and the mold, during the passage of it in the drying chamber. Means are provided to supply pressurized air to the interior of the mold so as to eject

the article once dry.

  The patents GB-1 137 761 and FR-1 399 753 are more re-

  cents but describe machines for manufacturing

  hollow pulp articles comprising similar means

  and in particular a mold wheel.

  It can be seen that, because of their rotation, these machines are complex, particularly with regard to the systems.

  In addition, the change of the molds on the wheel is a relatively long operation. These machines have important dimensions, because the molds must be fixed on a wheel.

  The size of the molded parts by these machines is limited. In particular, it is not conceivable to make parts with a width of 2 or 3 meters.

  These machines are intended to allow relatively high production rates and they are used for example for packaging and packaging of food products such as egg boots The known processes for manufacturing cellulose parts made from plastic pulp paper, implemented in particular by the use of the machines which have just been described, therefore consist in: 1) applying paper pulp into a cavity in the shape of the part and formed in a support, by suction through the aforementioned footprint of this support, so that the pulp is shaped on the impression, and 20) drying the previously deposited pulp

  These known processes require the use of at least three separate complementary tools and include

  The following successive steps are required: 1) Placing a metal grid in the shape of the desired part and defining the cavity, which is supported in a similar form of solid metal or another resistant material, intended to to avoid the deformation of the grid or imprint, relatively flexible This form of metal is pierced with a multitude of holes to allow aspiration through this grid

who is wearing it.

  ) Suction of the dough through the grid and

  the shape of metal or other resistant material.

  Drying of the molded part by passage in a tunnel furnace, wherein the part is driven by a conveyor belt which passes through the tunnel, the drying of the part being provided by blowing hot air jets along its path in the tunnel furnace, the hot air being at a temperature sufficient for the transformation of the residual liquid into vapor evacuated by a ventilation system In another embodiment of the drying step,

  the piece is dried by means of two complementary tools

tary:

  a first metal tool with an

  negative impression of the coin, and enclosing a set of

  electric resistances allowing the rise in temperature

  tooling at a temperature of between 2600 C and

  2900 C, the tooling and the impression being pierced by a multi-

  study of holes to let the vapor escape, a second tool, similar to the first in this

  that it has an impression of the room containing a

  seems of electric and heating resistances and is pierced with a multitude of holes, but such as its footprint

  positive form, and complementary to the negative form

  the first tooling of the tooling Each of the two tools necessary for the

  of the drying step of the presently used process.

  It is a complex embodiment and must have a shape corresponding to the part to be dried, which entails considerable cost and time for the manufacture of these devices.

  These processes therefore require the use of several

  tools, several weeks to several months

  be necessary for the manufacture of these tools, depending on the difficulty resulting from the problems of adaptation to

the shape of the piece to be dried.

  Moreover, these processes are expensive to implement because of their high energy consumption.

  for heating tools or tunnel kiln.

  In addition, the latter is cumbersome and its maintenance and maintenance complicate production operations

  As for the special drying tools described above,

  In the past, they are very expensive to manufacture and are only suitable for one size and shape of part. Therefore new tools have to be made, with all the resulting production complications.

for each different piece.

  As indicated above, the mold is generally constituted by an imprint, made of a metal grid shaped to the desired part and a similarly shaped element but made in particular of a metal

full of holes.

  It is understood that, in known machines, a vacuum

  important ration must be applied to the mold when it is filled with pulp Indeed, the mold is rotated by the wheel and the paper pulp is maintained in the mold by the suction applied. It is found that, because of the suction, the pulp penetrates the holes of the grid This forces

  only make parts that do not have counter

  In fact, a coin with a counter

  remains could not be demolded.

  This constraint causes significant disadvantages because it complicates the production of molds In addition, the presence of undercuts can be interesting to increase the volume impression of the parts obtained, especially in the case of making displays for cosmetics It can also be absolutely essential if one wishes to make sculptures by

example

  The present invention aims to remedy these drawbacks.

  to provide a variety of benefits, including

  to significantly simplify the implementation mechanism

  to propose a mold that can be quickly

  under 24 hours, to allow the production of parts of any size and may have

  undercuts and to allow economical implementation.

  and easy of the drying step, through the use of means in common with those used to conform the

rooms.

  For this purpose, the invention relates to a process for manufacturing parts from pulp, comprising:

  1) a shaping step in which one applies

  paper in a mold to the shape of the piece and 2) a drying step in which we bring the

  heat to the piece previously shaped in the mold.

  According to the invention, during the two stages, the mold is fixed and substantially horizontal, the inner part of the mold being directed upwards.

  the shaping step is maintained at room temperature

  te, an overpressure on the outside of the mold compared

inside the mold.

  Finally, during the drying step, a

  pressure of the outside of the mold with respect to

inside the mold.

  Advantageously, the intensity of the overpressure maintained during the shaping step is chosen so as to obtain a substantially homogeneous and uniform layer.

  of paper pulp inside the mold.

  According to a first embodiment of the invention, during the drying step, the room is supplied with heat by infrared radiation. Preferably, the radiation produces a temperature of between 100.degree. C. and 29.degree. C. According to a second embodiment of the invention, during the drying step, heat is supplied to the part by heating gases which are sucked in. through

  the room because of the depression.

  So that the drying of the part is as short and complete as possible, the hot gases sucked during the drying step are at a temperature between 1000 C and 2900 C. While the shaped part is still in the mold it is dried either by radiation and suction of gas, or by suction of gas previously heated through the mold and the support, so that all the steps of the manufacturing process is carried out until the molding of the molded part and dried, using the same tools for molding, or shaping, and drying In order to limit handling and to adapt to all forms of parts, the piece of pulp is demolded by injection of compressed air through

the mold, after drying.

  Alternatively, and in order to achieve cost savings, maintenance and handling for parts, said parts can, especially when they are large, be demolded by means of a vacuum suction device, which allows possibly to use the same source of aspiration as for the others

steps of the process.

  In order to increase the beauty of the room and give it

  better communication power, the process of

  In the latter case, an additional optional step of coloring the molded part by depositing pigments on the surface of the part or by adding pigments to the paper pulp is obtained.

tinted parts in the mass.

  In order to increase rigidity and aesthetics,

  molded parts can be metallized.

  So that parts placed outdoors or stored in damp or unprotected areas will withstand

  In tempers, the part manufacturing process includes an optional waterproofing step by a resin treatment. The invention also relates to a device for implementing the method which has just been described.

  According to the invention, the mold is made of a porous and non-hydrophilic material.

  Preferably, the material is resistant to thermal shock due to the passage of steam when the drying is ob-

  It is heated by suction of hot gases so that the service life of the mold is relatively long. For the same purpose, a material which does not oxidize is preferably selected. This material may be composite.

  Various details and advantages of the invention will become clear from reading the following description.

  BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show a part respectively during the shaping step and in the still wet state, and then during the step drying by suction. With reference to FIG. 1, the device according to the invention making it possible to manufacture parts from

  pulp, essentially comprises a mold 1, placed on a fixed support 2 The mold is disposed substantially

  The inner part 3 of the mold being directed upwards is made of a material porous to gases. Part 4 is shaped as follows:

  a suitable quantity of pulp is poured manually or by automatic means into the mold.

  1, and keep at room temperature for

  the forming step, an overpressure, on the outside 5 of the mold 1 relative to the inside 3 of the mold.

  This overpressure, the intensity of which is judiciously chosen, makes it possible to prevent the pulp from settling at the bottom of the mold, because of the gravity, and to maintain a uniform and homogeneous layer of paper pulp on the inner part 3 of the mold. mold During the drying step, a depression is established on the outer side 5 of the mold 1 with respect to the interior 3

  of the mold and bring heat to the room beforehand.

  This depression may, for example,

  can be obtained by means of a vacuum pump and a duct opening at the rear of the mold 1 These devices are not

not illustrated in the figures.

  This heat can be brought to the room by

  infra-red This radiation is produced by a

  appropriate positive which is not shown in the figures.

  This device produces a temperature including

1000 and 290 WC.

  The value of the

  radiation so that the room is heated without the

  This does not effectively protect the movement.

  thermal shocks It is also possible to dry the piece 4 in the mold 1 by sucking hot gases 6 through the part and the mold, the gas flow being directed from the top to the bottom of the mold.

  mold, as shown in Figure 2.

  This suction 6 of hot gases can for example be

  obtained by means of a heating device placed

  above the mold and heating gases that are sucked because of the depression This device is not shown in Figure 2 The gases used are preferably constituted

by ambient air.

  Thus, the heating device heats the air to a temperature of preferably between 1000 ° C. and 2900 ° C., and the hot air 6 is set in motion through the mold 1 and the part 4, shaped in the mold. by 9 - said pump mounted at the end of said suction duct, which dries the shaped part 1 which is still in the cavity. Due to the depression, the paper pulp is fixed in the mold. In fact, the mold, although not hermetic to pressure, is impervious to the paper pulp - which can not

  therefore not be dragged further by depression, and this

  the dough takes the shape imposed by the mold, while being dried because of the temperature of the radiation or the air

aspirated.

  Then the part 1 is demolded according to two alternative embodiments possible either by a distribution of compressed air, produced by a source of compressed air available in the workshop,

  this compressed air circulating in the same way as the air as-

  pumped, but in the opposite direction, and expelling the

piece 4 of the mold 1.

  a vacuum suction device which is placed on at least one outer surface of the part, and

  by moving the suction cup (s) on part 4.

  The mold 1 is preferably made of a material

non-hydrophilic.

  It is subject to significant thermal shocks when

  that the drying is provided by suction of hot gases and, to increase its lifetime, it is preferable to make it a material resistant to thermal shock For the same purpose, this material does not oxidize Preferably the mold 1 In particular, the process may comprise a composite material so as to be rapidly realized. The method may comprise an additional step, namely the function assigned to the part, of which here are certain specific examples. In a general manner, in order to present different aspects according to the different faces of the part. molded, so as to modify the communication power of the piece

  used, particularly as a display, the piece is colored

  in an additional step by all types of deposit

  pigments on the surfaces of said piece.

  According to another embodiment, the parts obtained

  were dyed in the mass by adding pigments in the pulp, prior to the different

  process steps which have just been described.

  According to a specific embodiment, the parts can be metallized

  In order to present a refined aspect

  For the display units, the color of the molded part

  be obtained by spray painting.

  In order to obtain different surface conditions, the process for manufacturing the molded parts may comprise an additional step of lacquering with or without cooking, which makes it possible to adjust the quality of the surface to the function

  the room and, moreover, to make the room totally impor-

permeable

  It is clear from the foregoing description

  that, because the mold is fixed and horizontal, the mold and

  therefore the piece can be of any size.

  In addition, the device is very simple compared to known devices In particular, the mold can be changed

  very quickly what is interesting in the technical field

  of the invention, when the series are small.

your quantities.

  The mold being arranged so that its lower part

  top is directed, the intensity of gas suction established during the drying step is much lower than that required in rotating wheel systems that do not use gravity. Thus, paper pulp penetrates much less into the inner surface of the mold and can be made parts with undercuts. Although the invention has been described in connection with a particular process, it is in no way limited thereto.

  and numerous variations can be made therein, such as, for example, all methods permitting vaporisation of residual liquid in the conformation mold without departing from the scope of the invention.

  The reference signs inserted after the technical features mentioned in the claims,

  are intended only to facilitate the understanding of these latter, and in no way limit its scope.

Claims (7)

  A method of manufacturing parts from pulp comprising: 1) a shaping step in which paper pulp is applied in a mold to the shape of the workpiece and 2) a drying step, in which brings heat to the previously shaped part   in the mold, characterized in that during the two stages   pes, the mold (1) is fixed and substantially horizontal, the inner part (3) of the mold being directed upwards, in that, during the forming step, is maintained at ambient temperature, an overpressure of side   outside the mold (5) relative to the inside (3) of the mold   (1) and that, during the drying step, it is   maintains a vacuum on the outer side (5) of the mold with respect to the inside (3) of the mold 2.A method according to claim 1, characterized in that the intensity of the overpressure maintained during the shaping step is chosen so as to obtain a substantially homogeneous and uniform layer of paper pulp to the interior (3) of the mold (1).   3.Procédé according to one of claims 1 or 2,   characterized in that during the drying step, it brings   from heat to room (4) by infra-red radiation.   4 Process according to claim 3, characterized in that the radiation produces a temperature of between 1001 C and 2900 C.   5.Procédé according to one of claims 1 or 2, ca   characterized in that, during the drying step, heat is supplied to the workpiece (4) by heating gases which are   sucked through the room due to depression.   6.Procédé according to claim 5, characterized in that   that said gases are constituted by the ambient air.   7.Procédé according to one of claims 5 or 6, carac-   characterized in that the hot gases (6) sucked during the drying step are at a temperature between 100 C and 290 C   8.A part manufacturing process according to any one of claims 1 to 7, characterized in that after   the drying step, the piece (4) is released from the mold (1) by injection of compressed air through the mold. 9.The process for producing parts according to one of claims 1 to 7, characterized in that after the step of   drying, the piece (4) is released from the mold (1) by means of a sucker suction device.   O.A process for manufacturing parts according to any one of claims 1 to 9, characterized in that   comprises an additional step of coloring the shaped part (4), by depositing pigments on the surface of said part   11.The method of manufacturing parts according to one of claims 1 to 9 characterized in that it comprises a   additional step of coloring in the mass of the piece   (4), by adding pigments in the pulp.   12 Process for manufacturing parts according to any one of claims 1 to 11, characterized in that   comprises an additional metallization step of the surface of the shaped part (4). 13 Process for manufacturing parts according to one of the   claims 1 to 12, characterized in that it further comprises a waterproofing step parts (4), by a   resin treatment. 14.Dispositif for the implementation of the method according to one of claims 1 to 13, comprising a   mold, characterized in that said mold (1) is made of a non-hydrophilic porous material.   15.Dispositif according to claim 14, characterized in that said material is resistant to thermal shock and does not   The apparatus according to one of claims 14 or 15, characterized in that said material is composite.