Cellulosic pulp mould comprising an impermeable outer surface
A pulp mould, comprising a porous sintered body ( 11 ) having an outer surface ( 13 ) and an inner surface ( 12 ), wherein a portion ( 11 B) of said mould comprises an area ( 16 ) at its outer periphery provided with means ( 16 A; 47 ) integrated during sintering to achieve impermeability of said outer area ( 16 ).
1. A pulp mould, comprising:
a porous sintered body having an outer permeable surface and an inner permeable surface;
a sealing stripe arranged within the porous sintered body such that within the porous sintered body a portion that is impermeable to vacuum and a portion that is permeable to vacuum is formed,
wherein the sealing stripe is arranged with at least one through hole; and
a heating coil arranged within the portion of the porous sintered body that is permeable to vacuum, the heating coil comprising:
an inner layer that is configured to be heated by electrical resistance;
an intermediate layer surrounding the inner layer, the intermediate layer comprising a lower portion that forms a heat insulator and an upper portion that forms a heat conductor to conduct heat from the inner layer to the porous sintered body; and
an outer layer surrounding the intermediate layer and sintered to the porous sintered body to transfer heat to the porous sintered body.
2. The pulp mould of claim 1 , wherein the sealing stripe is arranged between the portion of the porous sintered body that is impermeable to vacuum and the portion of the porous sintered body that is permeable to vacuum.
3. The pulp mould of claim 2 , wherein the sealing stripe comprises a material that will at least partly bond to the porous sintered body and wherein the thickness thereof is between 0.1-5 mm, preferably 0.5-3 mm.
4. The pulp mould of claim 2 , wherein the sealing stripe is open ended, and wherein the ends of the sealing stripe are arranged in contact with each other.
5. The pulp mould of claim 1 ,
wherein the portion of the porous sintered body that is made impermeable to vacuum by the sealing stripe further comprises a layer of sintered powder particles closer to the surface of the portion, and
wherein the sintered powder particles comprise fine sintered powder particles.
6. The pulp mould of claim 1 , wherein the portion of the porous sintered body is arranged by means of a portion of solid material that is integrated with the porous sintered body during sintering.
7. A method for producing a pulp mould comprising:
providing a porous sintered body having an outer surface and an inner surface;
dividing the porous sintered body by a sealing barrier embedded within the porous sintered body such that a portion of the porous sintered body is made impermeable to vacuum by the sealing barrier;
providing at least one through hole in the sealing barrier; and
providing a heating element within a portion of the porous sintered body that is permeable to vacuum, the heating element comprising:
an inner layer that is configured to be heated by electrical resistance;
an intermediate layer surrounding the inner layer, the intermediate layer comprising a lower portion that forms a heat insulator and an upper portion that forms a heat conductor to conduct heat from the inner layer to the porous sintered body; and
an outer layer surrounding the intermediate layer and sintered to the porous sintered body to transfer heat to the porous sintered body.
8. The method of claim 7 , wherein dividing the porous sintered body by a sealing barrier comprises: arranging a sealing barrier between the portion of the porous sintered body that is impermeable to vacuum and the portion of the porous sintered body that is permeable to vacuum.
9. The method of claim 8 , wherein the sealing barrier comprises a material that will at least partly bond to the porous sintered body and wherein the thickness thereof is between 0.1-5 mm, preferably 0.5-3 mm.
10. The method of claim 8 , wherein the sealing barrier is open ended and wherein said ends are arranged to be in contact with each other.
11. The method of claim 7 , wherein a surface of the portion that is impermeable comprises a layer of fine sintered powder particles.
12. The method of claim 7 , further comprising arranging the portion of the porous sintered body by means of a portion of solid material that is integrated with the porous sintered body during sintering.
13. The pulp mould of claim 1 wherein machining of a rear surface of the porous sintered body to form a flat surface is confined to a portion of the rear surface that is to be coupled to a tool plate.