Porous Mould Drum For Poultry, Pork, Meat-Replacement and Vegetarian Food

Abstract

A rotary cylindrical mould member for moulding products from a food starting material having at least one mould body having a curved outer surface, the at least one mould body is made from a porous material with a porous structure of intercommunicating pores, the outer circumference is at least partially sealed airtight, the at least one mould body has at least one mould cavity formed in the curved outer surface and having at its porous bottom wall and/or its porous sidewall and/or its boundary a deformation layer formed by plastic deformation from a milling operation, the mould member having a gas supply which forces a fluid gas through the inner volume and the deformation layer into the at least one cavity to assist the removal of moulded products, an average flow resistance of the deformation layer is 1-30% of the average flow resistance of the inner volume.

Claims

1. A rotary cylindrical mould member for moulding products from a food starting material comprising poultry, pork, meat-replacement and vegetarian food, the mould member, having a longitudinal axis and an outer circumference, the mould member comprising at least one mould body having a curved outer surface forming at least part of the outer circumference of the mould member and an opposite inner surface, wherein the at least one mould body is made from a porous material with a porous structure of intercommunicating pores, wherein the outer circumference is at least partially sealed airtight, wherein the at least one mould body comprises at least one mould cavity in which the food starting material is moulded, the at least one mould cavity being formed in the curved outer surface, the at least one mould cavity comprising at its porous bottom wall and/or its porous sidewall and/or its boundary a deformation layer formed by plastic deformation, from a milling operation, the at least one mould body comprises an inner volume provided between the deformation layer and the inner surface, the mould member further comprising a gas supply which forces a fluid gas through the inner volume and the deformation layer into the at least one cavity to assist the removal of moulded products from the at least one mould cavity, wherein an average flow resistance of the deformation layer (FR1) is 1-30%, 3-20%, or 4-15%, or 5-12% of the average flow resistance of the inner volume (FR2).

2. The rotary cylindrical mould member according to claim 1, wherein an average porosity of the inner volume is 15-50% or 20-45% by volume or greater than 25%.

3. The rotary cylindrical mould member according to claim 1, wherein an average pore size of the inner volume is 10-100 ?m or 40-110 ?m or determined using a linear intercept method.

4. The rotary cylindrical mould member according to claim 1, wherein the at least one mould cavity is a 2D-cavity having a porous bottom wall and a porous side wall, wherein the porous bottom wall is curved.

5. The rotary cylindrical mould member according to claim 4, wherein an average open surface porosity of the deformation layer of a cavity wall is greater than 10% or 15-35%, by area respectively.

6. The rotary cylindrical mould member according to claim 1, wherein the plastic deformation of the porous sidewall is higher than the plastic deformation of the porous bottom wall.

7. The rotary cylindrical mould member according to claim 1 wherein the at least one mould the cavity is a 3D-cavity comprising at least a contoured bottom wall.

8. The rotary cylindrical mould member according to claim 7, wherein the average porosity of the deformation layer is 10-50% or 20-40%.

9. The rotary cylindrical mould member according to claim 1, wherein an average thickness of the deformation layer of a cavity sidewall and/or cavity bottom wall is 0.05-1 mm or 0.1-0.2 mm.

10. The rotary cylindrical mould member according to claim 1, wherein a total average pressure drop (FR1+FR2) per cavity is 300-400 mbar at a gas flow rate, e.g., an air or N2, of 50 ln/min.

11. The rotary cylindrical mould member according to claim 1, wherein a total average pressure drop (FR1+FR2) per cavity is 120-160 mbar at a gas flow rate, e.g., an air of N2 of 20 ln/min.

12. The rotary cylindrical mould member according to claim 1, wherein a total average flow resistance (FR1+FR2) is 102-120% preferably 105-115% of the flow resistance of the inner volume (FR2)

13. The rotary cylindrical mould member according to claim 1, wherein a porous structure is defined that defines a continuous fluid flow path from the inner volume outward through a wall defining the cavity by which a venturi effect is realized through the deformation layer whereby a fluid passed from the inner volume through the deformation layer exhibits an increased velocity in the deformation layer relative to a velocity of the fluid within the inner volume.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The inventions are now explained according to the Figures. These explanations apply to all embodiments of the present invention likewise. The explanations do not limit the scope of protection of the present invention.

[0077] FIG. 1 depicts an inventive mould member.

[0078] FIG. 2 depicts a cross section of a cavity.

[0079] FIG. 3 depicts the determination of the linear porosity and linear pore intercept length.

[0080] FIG. 4 depicts a test sample cavity.

[0081] FIG. 5 is a micrograph of an illustrative cross section of a mould drum.

[0082] FIG. 6 is another photomicrograph that illustrates the presence of slip lines, a feature that is characteristic of a deformation layer.

[0083] FIG. 7A is a low magnification (30?) microscopic image of a cavity bottom surface.

[0084] FIG. 7B is a higher magnification image (200?) of the cavity bottom surface.

DETAILED DESCRIPTION

[0085] FIG. 1 shows an inventive cylindrical mould member 1, a drum, which comprises a porous mould body 6, in the present case a cylindrical mould body 6 made from one single piece. The porous mould body 6 is made from a sintered metal material, for example stainless steel, preferably 1.4404. The mould body comprises a plurality of cavities 2 at its outer circumference 5 which have been machined, preferably milled into the porous mould body. The cavities may have but need not have different shapes. The drum 1 rotates during production and in one rotational position, for example the 12 o'clock-position, a mass feed member (not depicted) is positioned in order to fill the cavity and in a downstream position, for example the 6 o'clock-position, a discharge device (not depicted) may be positioned in order to empty the cavity. After the cavity is emptied it can then be refilled again. The cavities are here provided in rows 9, here ten rows, which a plurality of cavities 2, here sixteen cavities, per row. The cavities in one row are filled and emptied simultaneously. The emptying of the cavities is supported by air (or another gas, such as nitrogen), which is forced in the emptying position and/or upstream therefrom through the porous body to eject the moulded products. The cylindrical mould member is therefore provided with passages 7, here one passage per row which extends beneath the porous body below one cavity, the so-called inner volume. In the discharge position, the passage is connected to a fluid source (e.g., an air-supply), which forces fluid (e.g, air or nitrogen) through the passage and the inner volume into the cavity and hence removes the moulded product from the cavity. Each cavity comprises a porous bottom wall 3 and a porous sidewall 4. At the outer circumference 5 of the drum, the pores of the porous mould body are closed, for example by smearing the pores with by deep rolling with a rolling element.

[0086] FIG. 2 shows schematically one half of the cross-section of a cavity 2, with a sidewall 4 and a bottom wall 3, which together form the boundary of the cavity, and an inner volume 10 below the cavity. The cavity 2 has been milled into the porous mould body 6. The inner surface 11 of the porous mould body 6 is in contact with the passage 7, which supplies a fluid (e.g., air, nitrogen, another gas or a cleaning fluid) to the cavities 2. As indicated by reference sign 8, during the milling process, a deformation layer is formed at the boundary of the cavity, both at the sidewall 4 and at the bottom wall 3 of the cavity. The deformation layer at the sidewall is preferably different from the deformation layer at the bottom wall, in terms of thickness and/or linear porosity. For removing a product from the cavity 2, a gas, preferably air or nitrogen is supplied via passage 7 (indicated by 7) to the inner surface of the mould body and flows then through the inner volume 10 and is then exited to the cavity 2 via the deformation layer 8 at the sidewall 4 and at the bottom wall 3. The same is true for a cleaning fluid.

[0087] FIG. 4 depict a test sample cavity 12 which was utilized to acquire the experimental data. All dimensions are provided in [mm]. The porous mould body 6 is made from sintered stainless steel, 1.4404 and is, as can be seen from the Figure on the right hand side, slightly curved. The porous mould body 6 was sealed at its outer circumference 5 and its four sidewalls 14 gastight, here by compressing the porous material at the surface. At the inner surface 11 of the porous mould body no sealing was applied. The area of the surface 11 is here 2348.69 mm.sup.2. Subsequently, a cavity 2 was machined into the porous mould body, here by milling and starting from the outer circumference 5. The cavity comprises a bottom wall 3, here a curved bottom wall and a sidewall 4. The bottom wall has a surface area of 1472.18 mm.sup.2 and the sidewall a surface area of 1040.92 mm.sup.2. Though stated as relatively precise dimensional values, the teachings herein also include relative proportionate dimensional values. Thus, stated another way for this depicted embodiment, it is possible that the proportion of relative surface areas of the bottom wall to the side wall may be 1.4:1. This value may deviate, for example, to a value within a range of 1:1 to 2:1.

[0088] The cavity has here a depth of 7.5 mm. After the insertion of the cavity, between the cavity and the inner surface 11 of the porous mould body, the inner volume 11 is left, which has a depth of 14.5 mm. Due to the machining of the cavity, a deformation layer results at its boundary, which is in contact with the product (not depicted).

[0089] In order to determine the individual flow resistances FR1 and FR2 of the deformation layer 8 and the inner volume 10, first of all, the total flow resistance FR.sub.Total of both, the deformation layer 8 and the inner volume 10, is determined by measuring the pressure drop ?P of a steady state gas flow Q, preferably air or nitrogen, across the porous mould body from the inner surface 11 to the cavity 2, as depicted by arrow 13. The total pressure drop includes the pressure drop of the constant gas flow while passing the inner volume and the deformation layer 8. The pressure drop is averaged over the entire cavity, i.e. over the entire test sample cavity, both bottom and sidewall. In the present case, only the pressure of the gas below the surface 11 is measured and it is assumed that the pressure of the gas downstream from the compressed layer 8 is ambient pressure, which is subtracted from the measured pressure at the surface 11 to calculate ?P. The total flow resistance is then calculated with the equation:

[00005]${\mathrm{FR}}_{\mathrm{Total}}=?P/Q$

wherein ?P is the pressure drop over the inner volume and the deformation layer and Q is the corresponding gas flow. The pressure drop is for example provided in [mbar]. Q is the gas flow rate at steady state, constant conditions provided in [ln/min]. ln is a volume at standard condition. i.e. 0? C. and 1 bar.

[0090] Subsequently, the compression layer 8 is removed, for example by electro polishing and/or EDM and then the flow resistance is again determined at the same gas flow rate Q in [ln/min] used to measure the total pressure drop, in order to determine the pressure drop ?P.sub.2 across the inner volume. This data is used to calculate the flow resistance FR2 of the inner volume utilizing the formula:

[00006]${\mathrm{FR}}_2=?P_2/Q$

wherein ?P.sub.2 is the pressure drop of the inner volume and Q is the identical gas flow in [ln/min] used to measure ?P.

[0091] The flow resistance FR1 can then be calculated as follows:

[00007]$\mathrm{FR}1={\mathrm{FR}}_{\mathrm{Total}}-\mathrm{FR}2.$

[0092] The flow resistances are preferably measured in a range of 2-100 [ln/min], preferably 5-50 [ln/min]. The selected gas is preferably air or nitrogen. Preferably, the measurements are taken at a range of different volume-flows, for example in steps of 10 [ln/min], from 10-50 [ln/min]. All data is acquired with a constant gas flow; i.e. the gas flow does not vary during the measurement (static flow conditions).

[0093] According to FIG. 3, the determination of the linear porosity with the linear intercept length is illustrated, (to demonstrate summarily the linear intercept method as it is described in ASTM-E112-13). The schematic graph depicts a porous cross-section, along which an artificial line is drawn, with the total measuring length [mm]. The drawing depicts what a skilled person may see upon examination of a photomicrograph created using conventional metallographic techniques. The technique described can be performed using a photomicrograph of a metallographic specimen prepared using conventional techniques for analysis of densified powder metal parts. In the present case, this line intersects 8 pores. The length of the interception L1-L8 is measured individually per pore and the sum ?L1-L8 is calculated and then divided by the total measuring length which results in the linear porosity. This procedure can be repeated several times and an average for the compression layer 8 and an average for the inner volume can be determined. The linear intercept length can be applied to the image of the surface of the deformed lager and/or to a cross-section of the porous mould body, in the deformed layer and/or in the inner volume.

[0094] This approach can be used to determine the average linear intercept Length, which is equivalent to the average pore size so that the disclosure above also applies. The equation to calculate the average intercept length is also provide in FIG. 3.

[0095] FIG. 5 is an annotated photomicrograph that illustrates portions of a cross section of a mould drum having a cavity and an inner volume. An exposed cavity bottom surface is depicted. Extending from the cavity bottom surface there is a deformation layer, and below that is the inner volume. It can be seen that the deformation layer in this micrograph is characterized by a markedly lower amount of porosity than the inner volume.

[0096] FIG. 6 is another annotated photomicrograph that depicts the presence of slip lines (following subjecting the sample to a suitable etch and then examining by scanning electron microscope). The presence of slip lines is a feature that may be expected to be within a deformation layer, but not within an inner volume of a mould drum in accordance with the present teachings. As can be seen in FIG. 6, progressing inwardly, away from the surface of the cavity wall, the presence of slip lines diminish and ultimately disappear.

[0097] FIG. 7A shows low magnification (30?) and FIG. 7B shows a higher magnification (200?) scanning electron microscope photomicrographs to illustrate open porosity in a cavity wall surface (e.g., a cavity bottom wall). A network of interconnecting pores can be seen penetrating into the mould body toward the inner volume.

LIST OF REFERENCE SIGNS

[0098] 1 cylindrical mould member, drum [0099] 2 porous product cavities [0100] 3 porous bottom wall [0101] 4 porous sidewall [0102] 5 outer circumference [0103] 6 mould body [0104] 7 passages [0105] 8 deformation layer [0106] 9 row of cavities [0107] 10 inner volume [0108] 11 inner surface [0109] 12 test sample cavity [0110] 13 gas flow [0111] 14 sidewall of the test sample [0112] FR1 flow resistance of the deformation layer [0113] FR2 flow resistance of the inner volume [0114] FR.sub.Total total flow resistance FR1+FR2 [0115] ?Pressure drop measurement