MOULD CONFIGURATION

Abstract

The invention is directed to a mould configuration (1) suited for use in a thermoforming forming station arranged to form one or more objects comprising a mould (2) made from a polymer material by additive manufacturing and provided a mould volume (6) consisting of a recess (6a) corresponding with the shape of the object as an upper zone (6b). A lower zone is divided from the upper zone by a recess wall (8). The lower zone (7) is provided with one or more open spaces (9) which fluidly connect the lower surface (8a) of the recess wall (8) with one or more openings (10) in the bottom (5) of the mould (2), a heat exchanger module (11) facing the bottom (5) of the mould (2) comprising cooling means (12) and cooling medium displacement means (13) and cooling medium inlet openings (14) and cooling medium outlet openings (15).

Claims

1. Mould configuration suited for use in a thermoforming forming station arranged to form one or more objects comprising a mould made from a polymer material by additive manufacturing and provided with an upper end, side walls and a bottom which is spaced apart from the upper end defining a mould volume, wherein the mould volume consists of a recess corresponding with the shape of the object as an upper zone, a lower zone which extends below the upper zone and divided from the upper zone by a recess wall, wherein the lower zone is provided with one or more open spaces which fluidly connect the lower surface of the recess wall with one or more openings in the bottom of the mould, a heat exchanger module facing the bottom of the mould comprising cooling means and cooling medium displacement means and cooling medium inlet openings and cooling medium outlet openings, wherein the cooling medium inlet openings and the cooling medium outlet openings are in fluid communication with the one or more openings in the bottom of the mould.

2. Mould configuration according to claim 1, wherein the open spaces, the openings in the bottom of the mould, the cooling medium inlet openings and cooling medium outlet openings of the heat exchange module, the cooling means and the cooling medium displacement means are part of one or more cooling medium flow paths for an cooling medium flow wherein, in use, the cooling medium flow cools the lower surface of the recess wall.

3. Mould configuration according to claim 2, wherein the cooling means are metal fins as present in the one or more cooling medium flow paths are directly connected to a metal surface and wherein in use the fins are reduced in temperature by thermal conduction between the relatively warmer metal fins and a colder metal surface.

4. Mould configuration according to claim 1, wherein the thickness of wall is between 0.5 and 5 mm.

5. Mould configuration according to claim 1, wherein the mould is positioned above the heat exchange module within a single container, wherein the container has a metal bottom, side walls and an open upper end such that the recess of the mould is accessible from above.

6. Mould configuration according to claim 5, wherein the container and the mould are part of a modular configuration allowing replacement of the mould by a different mould.

7. Mould configuration according to claim 6, wherein the replaceable mould is removably placed in a mould holder suited to hold one or more moulds and wherein the mould holder and the one or more moulds are positioned on top of the heat exchange module within the container thereby fixating the moulds relative to the heat exchange module.

8. Mould configuration according to claim 5, wherein the container comprising the heat exchange module is designed such that it can be positioned on a cooled surface of a thermoforming forming station and wherein in use the metal surface is reduced in temperature by thermal conduction between the relatively warmer surface and the cooled surface of the thermoforming forming station.

9. Mould configuration according to claim 8, wherein the thermoforming forming station and the container are part of a modular configuration allowing container to be replaced by a different container in the thermoforming forming station.

10. Mould configuration according to claim 1, wherein the cooling medium displacement means are liquid medium displacement means, preferably pumps.

11. Mould configuration according to claim 1, wherein the cooling medium displacement means are gas displacement means, preferably ventilators, more preferably centrifugal fans.

12. Mould configuration according to claim 3, wherein the heat exchange module is comprised of a set of more than one cooling medium displacement means and metal fins positioned relative to the cooling medium inlet and cooling medium outlet openings such to create in use multiple opposing cooling medium flows which set is dimensioned to cool one mould.

13. Mould configuration according to claim 12, wherein the cooling medium displacement means are centrifugal fans having a cooling medium outlet directed upwards towards a row of cooling medium outlet openings.

14. Mould configuration according to claim 10, wherein the one or more spaces are air tight sealed from the upper zone.

15. Mould configuration according to claim 1, wherein one heat exchange module is fluidly connected to the lower end of more than one moulds.

16. Thermoforming forming station comprising a mould configuration according to claim 1.

17. Use of a thermoforming forming station according to claim 16 to form a polymer sheet by drawing the sheet into the mould and wherein the polymer material of the mould has a glass transition temperature which is lower than an operating temperature of the thermoforming forming station and wherein the melting temperature of the polymer is higher than the operating temperature of the thermoforming forming station and wherein the operating temperature of the thermoforming forming station is hereby defined as the temperature of the polymer sheet as it is drawn into the polymer mould.

Description

[0027] The invention will be illustrated by making use of the following non-limiting FIGS. 1-6.

[0028] FIG. 1 shows a mould (2) provided with an upper end (3), side walls (4) and a bottom (5) which is spaced apart from the upper end (3) defining a mould volume (6), wherein the mould volume (6) consists of a recess (6a) corresponding with the shape of the object as an upper zone (6b).

[0029] FIG. 2 shows a cross-section of the mould (2) of FIG. 1. A lower zone (7) which extends below the upper zone (6b) is divided from the upper zone (6b) by a recess wall (8), wherein the lower zone (7) is provided with one or more open spaces (9) which fluidly connect the lower surface (8a) of the recess wall (8) with one large single opening (10) in the bottom (5) of the mould (2).

[0030] FIG. 3 shows an exploded view of how four moulds (2) of FIGS. 1-2 are combined with a heat exchange module (11) in a single container (19). The container has a metal bottom (20), side walls (21) and an open upper end (22) such that the recess (6a) of the mould (2) is accessible from above. The four moulds (2) fit into a mould holder (23) from below. By fixing the mould holder (23) by screws to container (19) the moulds are mixed. By simple unfixing the mould holder (23) the moulds (2) may be replaced by other moulds (2).

[0031] When the mould holder (23) with the moulds (2) are positioned in the container the single openings (10) of all four moulds (2) are in open fluid communication with the air inlet (14) and air outlet (15) openings as present at the upper side of the heat exchange module (11) using air as the cooling medium. When assembled the space below the moulds (2) is gas tight separated from the space above the moulds. The recess wall (8) may be provided with small openings (not shown) to allow air to escape when the moulded sheet product is made. moulds themselves. Also shown are openings (24) to which a vacuum pump may be attached or a one way valve such that excess air can momentarily escape during the thermoforming process. Indentation (25) in the bottom (20) of the container (19) fits on a rail (26) of a cooled support plate (27) of a thermoforming forming station as shown in FIG. 6.

[0032] FIG. 4 shows a heat exchanger module (11) using air as the cooling medium and provided with four sets (28) of centrifugal fans (31) as air displacement means (13) and metal fins (32) positioned below each mould (2). Per mould six centrifugal fans (31) are present. The air flows through openings (14) to the centrifugal fans (31) along the metal fins (32) and upwards to the air outlet (15). In this configuration air flows downwards and upwards through the same opening (14,15) resulting in six opposing air pathways.

[0033] FIG. 5 shows a cross sectional view of the assembled container (19) of FIG. 3. An air flow is illustrated from the open spaces (9), the openings (10) in the bottom (5) of the mould (2), the centrifugal fan (31), the metal fins (32) and back via air outlet opening (15) to open space (9). This cool air flow will cool the lower surface (8a) of the recess wall (8).

[0034] FIG. 6 shows the assembled container of FIG. 5 as placed on a on a rail (26) of a on a cooled support plate (27) of a thermoforming forming station. The assembled container may also be used in isolation, ie without a thermoforming forming station. This may be advantageous when relatively warm moulds are removed from the thermoforming forming station. By maintaining the air flow the moulds may be further cooled while being disassembled from the thermoforming forming station.