Patent Description:
Food forming drums are utilized in machines, which form food products, like patties from a food mass. Such an apparatus is for example described in the patent application <CIT>. Another food forming drum apparatus can be found in the document <CIT>.

However, the food forming drum described in this patent application is difficult to produce and has hygienic problems.

It was therefore the objective of the present invention to provide a food forming drum, which does not have the deficiencies of the devices according of the state of the art.

This problem is attained by a food forming drum comprising a multitude of rows of porous product cavities, each row comprising one or a multitude of porous product cavities, the drum preferably comprising a first and a second front end and preferably fluid channels in the longitudinal direction of the drum each fluid channel preferably connecting one row of porous product cavities fluid-wise, wherein the porous product cavities are provided as one or more insert(s) which is/are connected to the drum by an adhesive connection, form- and/or friction-fit.

The disclosure made to this embodiment of the present invention also applies to the other inventive embodiments of the present invention and vice versa.

The present invention relates to a food forming drum, which is part of a food forming apparatus. This food forming drum has at its outer surface a multitude of product cavities, which are open towards the circumference of the drum and in which the food mass is formed into a food product, for example a patty. This food forming drum comprises, according to the present invention, a multitude of rows of product cavities, whereas each row comprises one or a multitude of product cavities, side by side. The rows are arranged in parallel to the middle axis of the inventive drum. During production, the drum turns and in one position the product cavities in one row are filled with the food mass and in a downstream position, the formed food mass is discharged from the product cavities, located in one row. Subsequently, the product cavities in one row of cavities can be filled again and so on. In order to vent the product cavities during their filling and/or in order to support the discharge of the product, the product cavities are at least partially made of a porous material, which is gas-permeable and via which the product cavity can be vented or through which gas, for example air, can be discharged, to loosen the formed product from the surface of the product cavity. Preferably, the porous material comprises channels, which are interconnected.

The food forming drum further preferably comprises fluid channels, which extend in the longitudinal direction of the drum, i.e. parallel to the center axis of the drum and extend preferably from one end to the other end of the drum. Via each fluid channel, ventilation air can be discharged, for example to the ambient, and/or compressed gas can be forced into the cavities to discharge the formed product. Additionally, a cleaning fluid can be forced through the channels and/or the porous material of the product cavities.

The ends of the drum can be covered with an end cap, respectively or can be open.

According to the present invention, the porous product cavity is provided as an insert, which is fixed to the drum. This embodiment of the present invention has the advantage that the drum itself does not need to have a porous layer. Each insert may comprise a porous part or is preferably made entirely from porous material. One insert may comprise more than one porous product cavity. In a preferred embodiment, all porous cavities of one row are provided as one insert. According to another preferred embodiment, more than one insert is provided per row.

According to a preferred embodiment, the porous part comprises a back-up ring. This back-up ring covers at least a portion of the porous part, for example the circumference and/or the front edge at least partially. This assures that the porous material is protected and/or that gas does not leak through surface areas of the porous material, where a gas-flow is not needed or not wanted.

Alternatively or additionally, the surface area of the porous material, where a gas flow is not needed or even not wanted, can be machined such, that the pores are at least partially, preferably entirely closed.

According to the present invention, each porous insert is connected to the drum by an adhesive connection, form- and/or friction-fit. Additionally or alternatively, two inserts are connected by an adhesive connection, form- and/or friction-fit. This embodiment of the present invention assures that the porous product cavity and/or the inserts stay in their desired position during filling, discharge of the product and/or cleaning of the drum and/or that there is no gap between the drum and the insert and/or between two inserts, into which food product can migrate. The inventive drum is very hygienic, easy to produce and to clean. The drum will, preferably be provided with recesses for the porous material or an insert that comprises or is entirely made from the porous material. In this recess, the porous material and/or the insert is placed and then connected to the drum by an adhesive connection, form- and/or friction-fit. An adhesive connection can be, for example, attained by gluing, welding, brazing and/or soldering. A form- and/or friction-connection can be achieved by mechanically bonding the porous material or the porous insert to the drum.

Preferably, the connection between the insert and the drum is irreversible, i.e. it cannot be loosened without destroying the drum, the connection and/or the insert.

A preferred way to solder is known as flux-free soldering. Here the solder is provided in the form of a film/foil (suitable for use in the food processing industry) will be wrapped around the circumference of the insert, particularly provided in the contact area between the insert and the drum, preferably its outer member. Subsequently both, the insert and the film/foil, will be placed into the recess of the drum, particularly its outer member. Then the drum assembly will be heated for a certain time period and temperature, for example, in an oven. Preferably this heating process takes place under vacuum. The foil/film will melt and form a solder connection between insert and recess of the drum. Subsequently, the drum will be cooled down again. This method gives a good connection between the insert and the drum and the process is stable and clean. However other methods to obtain an adhesive connection between the insert and the drum are feasible as well.

The porous part of the porous product cavities and/or the insert are, preferably or according to another or a preferred embodiment of the present invention, connected to the drum by bridges of a plastic material, for example epoxy, and/or a molten metal or a molten alloy.

According to another inventive or preferred embodiment of the present invention, the porous product cavity is made as an insert and comprises a porous part and preferably a back-up ring.

The disclosure made to this embodiment also applies to the other subject matters of the present invention and vice versa.

According to another inventive or preferred embodiment of the present invention, the porous part and/or the insert are placed from inside to the sidewall of the drum against a flange of the drum.

Since the drum is preferably hollow, the porous material or the insert comprising the porous material can be placed from inside to the sidewall of the drum and fixed in the desired position.

According to yet another preferred or inventive embodiment of the present invention, the drum comprises a recess for the porous part of the porous product cavities and/or for the insert, whereas the recess comprises support means for the porous part and/or the insert.

This embodiment of the present invention is particularly advantageous for large product cavities in order to avoid, that the porous material is damaged during its filling, emptying and/or cleaning.

The disclosure made to this embodiment also applies to the other embodiments and vice versa.

According to another or a preferred embodiment of the present invention, the cavities are provided as a porous insert, which is connected to the drum irreversibly, i.e. once connected, they cannot be removed from the drum without destroying the drum, the insert and/or their connection.

Preferably the insert is glued, welded, brazed and/or soldered to the drum.

According to another preferred or inventive embodiment of the present invention, the drum comprises a multitude of, preferably essentially cylindrical, sidewall members, whereas one member is preferably a thin sheet member. The sidewall members are arranged concentrically and connected to each other. The thin sheet member is preferably a stainless steel sheet, which is extension- and/or shrink-fitted with another member, preferably a porous member of the drum. In another preferred embodiment, the thin sheet member is adhesively connected, preferably welded, soldered or brazed to another member, preferably a porous member.

The disclosure made to this embodiment of the present invention also applies to the other embodiments and vice versa.

According to another preferred or inventive embodiment of the present invention, a fluid channel and/or support means is part of the porous member or an insert, preferably a porous insert. The fluid channel and/or support means can be for example machined, drilled and/or milled into the porous material and/or the porous insert. The fluid channel preferably extends parallel to the center axis of the drum.

The disclosure made to this embodiment also applies to the other embodiments of the present invention and vice versa.

According to another preferred or inventive embodiment of the present invention, the drum comprises a multitude of fluid channels per row. These fluid channels preferably extend from one end to the other end, respectively and are preferably arranged in parallel, each preferably parallel to the center axis of the drum. These channels can be exposed to, for example compressed air to discharge a product and/or a cleaning fluid, simultaneously or sequentially. One or more fluid channels can be connected to the bottom and/or one or more fluid channels can be connected to the sidewall of the porous product cavity. By connecting at least one fluid channel to the sidewall and one to the bottom of the porous product cavity, the sequence of ejection of a fluid can be freely chosen. Pressurized fluid, for example air can be ejected firstly out of the bottom and then out of the sidewall of the porous product cavity or vice versa. It is also possible to eject a fluid out of the bottom and the sidewall of the porous product cavity, at least essentially simultaneously.

According to another preferred or inventive embodiment of the present invention, the sidewall and the bottom of the porous cavity have different flow-resistances regarding the fluid flow of the fluid to remove the formed food product from the product cavity. The disclosure made to this embodiment of the present invention also applies to the other embodiments of the present invention and vice versa.

Due to the difference in the flow-resistance, it can be achieved that the amount of fluid, for example air, through the bottom and through the sidewall of the porous cavity can be different and/or that there is a phase shift between the discharge of the fluid at the bottom relative to the discharge of the fluid at the sidewall of the porous cavity. Preferably, the fluid discharge is firstly initiated at the sidewall and then at the bottom.

Preferably, the thicknesses of the porous material at the bottom differs from the thickness of the porous material at the sidewall. More preferably, the thickness of the porous material at the sidewall is thicker or thinner than the thickness of the porous material at the bottom of the porous cavity.

Alternatively or additionally, the surface of the porous material at the sidewall has a different, higher or lower, flow-resistance than the surface of the porous material at the bottom, particularly for the medium, for example air, that is utilized to eject the product from the porous cavity. More pores on the surface of the porous material at the sidewall are closed than pores on the surface of the porous material at the bottom of the porous cavity or vice versa.

According to yet another preferred or inventive embodiment of the present invention, the thickness of the porous material varies within the bottom and/or within the sidewall. This embodiment of the present invention allows to influence the flow distribution for example of the discharging- and/or the cleaning fluid along the bottom and/or the sidewall.

According to another preferred or inventive embodiment of the present invention, the drum comprises a multitude of sidewall members whereas preferably the inner member or intermediate member is entirely a porous member. The sidewall members are preferably arranged concentrically.

According to another preferred or inventive embodiment of the present invention, the porous product cavity is made as an insert and secured to the drum by a sidewall member. The sidewall member preferably has a cylindrical shape.

According to yet another preferred or inventive embodiment of the present invention, the drum is at least partially casted. This embodiment of the present invention simplifies the production of the drum, because, for example, the fluid channels need not be machined into the drum.

The disclosure made to this embodiment of the present invention also applies to the other embodiments of the present invention and vice versa.

According to another inventive or preferred embodiment of the present invention, the volume of each product cavities is smaller than the desired volume of the product.

The disclosure made of this embodiment of the present invention also applies to the other embodiments of the present invention and vice versa.

In another inventive or preferred embodiment of the present invention, each fluid passage is, at its ends, covered with a cover, which disconnects each fluid passage from a fluid supply, whereas this cover comprises a recess and/or is pivotable. With this cover, the fluid supply to the fluid passages can be controlled.

Another preferred or inventive embodiment of the present invention is a process for the manufacturing of the drum, whereas the outer diameter of the drum will be provided slightly larger than the desired final diameter of the drum, the porous inserts are placed in the sidewall of the drum and the sidewall of the drum then the drum gets it final diameter by, for example machining, preferably milling the surface of the drum. During this machining, the pores on the surface of the porous inserts facing the outer circumference of the drum are at least partially closed.

Another preferred or inventive embodiment of the present invention is a process for manufacturing the drum, whereas the porous material of the porous product cavities is deposited in the sidewall of the drum.

Before securing a porous insert in a drum, it is preferred to close the pores of the porous insert in certain surface-areas, particularly in the contact area between the porous insert and the drum, at least partially. The closure can be accomplished by grinding or laser-polishing, this area, coating the area, for example with a molten metal, and adhesive such as epoxy, laserpolishing or by soldering. Preferably, the pores will be close by blasting or shot-peening. During shot-peening, the porous surface is impacted with shots of particles, for example ceramic particles. The surface of the porous material, which is subjected to blasting or shot-peeling deforms plastically so that the pores on the surface are closed at least partially. Another preferred method to close the pores on the surface of the porous material is impregnation, particularly vacuum-impregnation for example with a resin. Preferably, the surface of the porous material is treated by electropolishing for example to achieve a smoother surface and a reduced product adhesion.

All subject matters of preferred and inventive embodiments of the present invention can be combined in new claims.

Removing of the formed products out of product cavities can be done in several ways.

In case the product cavities are only provided with a porous bottom, fluid will only to be provided in a passage which is directed to the porous bottom. In case the product cavities are provided with a porous bottom and a porous sidewall fluid has to be provided to both the bottom wall and sidewalls.

Preferably or according to another inventive concept, each insert is sintered, preferably from a metal material. Each insert is fixed, preferably by an adhesive connection, to the drum. More preferably, each insert is soldered to the drum. Preferably, each insert extends, at least essentially, over the entire length of the drum. More preferably, the drum comprises an end cap, more preferably at each end. Each end cap is preferably designed as a circular ring. The end cap is connected to the drum by a form- and/or force-fit, more preferably screwed to the drum.

Preferably, the drum comprises at least one groove per row of cavities, which extends over the entire lengths of the drum. Preferably, the cross section of the groove is dove tailed. One or more Inserts with a corresponding diameter, preferably one insert per product cavity or one insert per row, can be inserted from a frontend, preferably each frontend, into the groove. The inserts are at least partially made from a porous material and the cross section is shaped such, that there is a form-fit between the groove and each insert, respectively, due to the dove tailed cross section. Preferably, the inserts are connected to the drum by an adhesive connection, more preferably soldering, welding or brazing. Each insert can also be fixed to the drum by a form- force- and/or friction-fit. Alternatively or additionally, each row comprises one or more pressure elements, which, for example, pushes the inserts towards the circumference of the drum and thus reduces the gap between the insert and the surface of the drum. The gap between the insert and the drum can be closed as disclosed above. One or more fluid passage(s) is/are provided between the insert and drum. The joint length of all inserts in one row is preferably longer than the longitude extension of the drum. After the inserts have been placed into the drum, the inserts can be pressed together and/or against the drum by means of one or more pressure element(s) and one or two end cap(s) is/are provided at least at one front-end of the drum.

Preferably only one insert per row is provided which comprises all product cavities of this row respectively. However, it is also possible to have a multitude of inserts per row, whereas each insert may comprise more than one cavity.

Preferably, the drum comprises an essentially cylindrical inner member with grooves for at least one, preferably a multitude of inserts. Preferably each insert is sintered, preferably from a metal material. Each insert is fixed, preferably by an adhesive connection, to the drum. More preferably, each insert is soldered to the drum. Preferably, each insert extends, at least essentially, over the entire length of the drum. More preferably, the drum comprises an end cap, more preferably at each end. Each end cap is preferably designed as a circular ring. The end cap is connected to the drum preferably by a form- and/or force-fit, more preferably screwed to the drum.

In the following several embodiments will be described to control the flow of fluid in such way that fluid will enter the product cavity first via the bottom wall and then the sidewalls or first via the sidewalls and then the bottom wall.

The inventions are now explained in further detail according to the subsequent figures. This disclosure does not limit the scope of protection of the present invention. The descriptions apply to all embodiments of the present invention, respectively.

<FIG> shows the inventive food forming drum, which is part of a food forming apparatus, which forms a food mass into a food product for example a patty. Along its circumference, the drum <NUM> comprises a multitude of rows <NUM> of cavities <NUM>. In the present case, one row comprises five cavities <NUM>. In each cavity <NUM> a product can be formed. During the forming of the food products, the drum rotates so that in one position, the cavities <NUM> in one row <NUM> are filled, while downstream from this position, the food products in a row are discharged from the cavities. Preferably the drum is hollow and comprises at its first front end <NUM> and its second front end <NUM> an end-cap <NUM>, respectively. At least one fluid channel <NUM> per row <NUM> extends over the entire length of row <NUM> and including both end caps <NUM>. This longitudinal channel <NUM> is, as later described in further detail, connected fluid-wise to each product cavity <NUM> in one row, in order to vent these cavities during their filling, to force a fluid through the cavities to discharge the formed product and/or to force a cleaning fluid through the cavities. In order to bear the drum rotatably in the forming apparatus and/or in a cleaning apparatus, the first front end <NUM> and the second front end <NUM> each can comprise a journal <NUM> connected to the frond ends <NUM>, <NUM>, respectively. However, the inventive drum can also comprise a long shaft over the entire length of the drum, which extends out of the front ends <NUM>, <NUM>, respectively. Other bearing solutions are possible, too.

According to the present invention, the product cavities <NUM> are at least partially made from a porous material which is permeable for a fluid, for example a gas and/or a cleaning fluid. Via the porous section of the product cavity, the product cavity can be vented during filling and the formed product can be loosened from the product cavity by means of ejecting gas. The porous material is preferably a sintered material. The porous material can be an entire circumferential layer/member of the drum, into which the product cavity <NUM> is preferably machined. Alternatively, the porous part of the product cavity can be provided as an insert. In this case, the drum preferably comprises one or more, preferably stainless steel members, each preferably provided as a tube, which are connected together. The porous material will be provided as an insert, which will be fixed to the drum.

<FIG> shows a first embodiment of such an insert <NUM>. This insert <NUM> comprises a porous bottom <NUM> and a porous sidewall <NUM>, whereas the porosity of the sidewall and the bottom can differ. The surface of the sidewall <NUM> and the bottom <NUM> define the product cavity <NUM>, in which the food mass is formed into the desired shape, here a disk. The inner surface of the sidewall <NUM> is, at least partially, slightly conical in order to simplify the discharge of the product. At its top surface, the sidewall comprises a closed region <NUM>, to avoid air leakage in this region during the discharge of the product with compressed gas, for example air and/or for hygienic reasons. The porous part of the insert <NUM> can be made from a piece of commercially available porous material. The person skilled in the art understands, that the porosity of the bottom and the sidewall can also be identical. The insert can also be made by rapid prototyping; i.e. by 3D-printing of a molten metal powder. Layers with different porosity and/or layers which are not porous can be created in this way. In the example according to <FIG>, insert <NUM> is provided with a sidewall with porosity A, a bottom with porosity B and a region <NUM> with no porosity.

<FIG> shows yet another embodiment of the insert <NUM>. In the present example, the insert <NUM> is sintered and build up in layer <NUM>, <NUM> with different porosity. The lavers <NUM>, <NUM> can also be prefabricated and then attached to each other. In the present example, the bottom part <NUM> has a larger porosity (i. less mass per volume) than layer <NUM> in order to reduce the air flow resistance of this layer. The layer <NUM>, which is in contact with the food mass to be formed preferably has a lower porosity (i. more mass per volume) than layer <NUM>, to avoid or reduce penetration of the food mass into the porous layer. The top layer <NUM> is for example not porous at all. As can be also seen from this example, the thickness of the entire porous part and/or the thickness of the individual layers can vary over the extension of the product cavity to direct the fluid flow to discharge the product from the cavity and/or the cleaning fluid into desired regions of the product cavity. It can be for example desirable, to have a higher air flow at the outer region of the bottom and/or along the sidewalls to loosen the formed product in this region. However, a uniform flow-pattern over the entire bottom and/or the sidewall can also be desirable.

In <FIG> the manufacturing of the drum <NUM> is depicted. Preferably, the drum is made from a commercially available thick-walled tube, preferably a stainless steel tube. This tube is preferably provided with a slightly larger diameter than the desired final diameter of the drum <NUM>. Subsequently, recesses <NUM> for the insert <NUM> or the porous material are machined into the drum, where later on a product cavity <NUM> will be placed. Simultaneously afterwards or before the longitudinal channel <NUM> can be machined for example drilled into the drum, from one end of the drum to the other end, whereas one row of recesses (here five recesses) is provided with at least one longitudinal channel <NUM>. Via this channel <NUM>, the product cavities <NUM> will be later vented, provided with a compressed gas to discharge the product and/or with a cleaning fluid to clean the passage <NUM> and/or the product cavities <NUM>. The fluid channel <NUM> extends from one and of the drum to the other front end of the drum. All other holes and recesses, for example for connecting the end-caps to the drum, can be provided too. The person skilled in the art understands, that the drum can also be made by casting. In this case, at least some channels and other holes needed are preferably part of the cast. This preferred embodiment of the present invention has the advantage, that the subsequent machining is at least reduced.

In the next step, each insert, which comprises at least partially porous material, will be placed in one recess of the drum, respectively and fixed in this position. The fixation of the insert and/or the porous material itself in the drum will be explained later on. In a following step, the drum gets preferably its final desired diameter. During this step, the top surface of the inserts can be closed, if desired. In the next step, if not already carried out, the product cavities can be machined into the porous inserts. This can be for example done by milling, whereas the tool needs a sharp cutting edge. Preferably the removal of porous material will be done by EDM. When the product cavities are inserted into the drum, in a lot of cases, the final weight of the formed product is too large. A correct final weight of the formed product can be achieved by making the diameter of the drum slightly smaller, for example by reducing the diameter of the drum after the inserts have been inserted into the drum. The end-caps <NUM> are preferably bolted to the tube and have sealing to prevent that meat particles and/or cleaning fluid enters the drum assembly. Depending on the design it is also possible to bolt the end-caps to the drum before placing the inserts into the sidewall of the drum. The drum is a component of a forming apparatus which will be exchanged regularly for example for cleaning-purposes. Therefore, a light weight drum is desired. The strength and stiffness in combination with al low weight of the drum can be optimized, by example by using a central axis which extends at least over the entire length of the tube. Additionally, the tube <NUM> can comprise reinforcement means, for example reinforcement rings at its inner surface. The drum is preferably made from stainless steel. To minimize wear of the surface of the drum during production of the formed products, it is recommended that the outer surface of the drum has a high wear resistance.

<FIG> shows an example of a porous insert <NUM>, which can be directly placed into the drum. The top surface of the bottom and the inner surface of the sidewall define the product cavity <NUM>. Around its circumference, the porous insert has optionally a circumferential fluid channel <NUM>. Via this fluid channel <NUM> gas can be forced through the porous sidewall, to loosen the formed product from the sidewall, and/or a cleaning fluid can be provided to the sidewall. The circumferential channel <NUM> is connected to the main fluid passage <NUM> via horizontal fluid connections (here three fluid connections).

<FIG> shows yet another embodiment of the insert <NUM>. Essentially, this insert <NUM> is designed as the insert according to <FIG>. However, in the present case, the porous part <NUM> is covered by a cover <NUM>, here a back-up ring. Thus, the insert <NUM> comprises two parts <NUM> and <NUM>. The back-up ring <NUM> extends around the entire circumference of the porous part <NUM> and has additionally a contact surface 51at the top the of the porous part <NUM>. As already explained above, the channel <NUM>, machined in the porous part <NUM>, is optional.

<FIG> shows yet another embodiment of the insert <NUM>. Again, the insert <NUM> has, a porous part <NUM> and a back-up ring <NUM>. In the present case, this back-up ring comprises fluid channels <NUM>, which are however again optional. In contrast to the embodiment according to <FIG>, in the embodiment according to <FIG>, besides the circumferential connection between the back-up ring <NUM> and the porous insert <NUM>, there is a contact surface <NUM> at the bottom of the porous part <NUM>.

In case that only a porous material is inserted into the recess of the drum, this porous insert <NUM> has to be tightly fitted into the recess to prevent loosening or disconnection of the porous material from the drum <NUM> during production or cleaning. In cases where the porous material <NUM> is covered by a cover of a back-up ring <NUM>, a close connection is needed between the porous material <NUM> and the back-up ring <NUM> and particularly between the back-up ring and the drum. All connections have to be so tight that no gaps, into which the food mass can penetrate, are existent. In case gaps are present, they have to closes by means described below.

All materials used in connection with the drum have to be approved for use in the food-industry.

Means how to secure the insert in the drum is now explained in further detail.

In general, the insert <NUM> can be pressed into the recess of the drum. In case, that the insert to be pressed is only a porous part <NUM>, the pores of the porous material can be partially closed and porosity will be lost. Thus, a press connection of the porous part is only an alternative in case no air flow is desired in the deformed porous part.

Alternatively or additionally, the insert can be shrink-connected with the drum. In this case the insert <NUM> particularly the porous part <NUM> is cooled down and then can be placed in a back-up ring <NUM> or directly in the recess of the drum. Mounting tension is thus largely avoided. The tightest fit can be achieved by a combination of shrinking the insert and heating the drum and/or the back-up ring. The person skilled in the art understands, that the same technique can be used to assemble the entire insert <NUM>, comprising a porous section <NUM> and a cover <NUM>, in the drum.

As depicted in <FIG>, the insert <NUM>, including a cover <NUM> or not, can be welded or brazed (compare reference sign <NUM>) to a recess of a drum and/or the porous part <NUM> and the back-up ring can be welded or brazed together as depicted by reference signs <NUM>. Welding/Brazing line <NUM> is optional in case a shrink and/or press connection exists between the insert and the drum. The Welding/Brazing is preferably carried out by laser-welding, laser-brazing. The laser is preferably moved in a pre-programmed pass with a relatively low heat transfer. Welding/Brazing technique can also be utilized to close pores of the porous material, for example at the area around the Welding/Brazing line. By closing the porous, the porosity disappears and the solid piece of metal is created which is less sensitive during Welding/Brazing and which cannot be penetrated by a gas.

<FIG> shows an embodiment of the present invention, where the porous material <NUM> is soldered to a cover/back-up ring and/or directly to a recess of the drum. The person skilled in the art understands, that the back-up ring can also be soldered to the drum. In the present case, the porous insert <NUM> is placed into a recess of the drum. To assure a, preferably constant, gap between the circumference of the insert and the recess, the circumference of the porous part <NUM> of the insert and/or the insert <NUM> itself will be provided with ridges. The assembly of drum <NUM> and insert <NUM>, <NUM> will be preferably heated and when the desired temperature is achieved, heated solder <NUM> will be applied. Entrapped air can escape via the porous structure. The porous material of the insert will soak up the flux and solder. After the inserts <NUM>, <NUM> are placed and secured in the drum, the drum can be machined to its final diameter.

In the embodiment according to <FIG>, the solder is replaced by a bonding agent for example a glue.

In the embodiment according to <FIG> the inserts <NUM> and/or the porous part <NUM> is secured to the recess of the drum with an epoxy, preferably a stainless steel epoxy. In case the insert <NUM> comprises a porous part <NUM> and a cover/back-up-ring, the porous part <NUM> and the back-up ring <NUM> can also be secured to each other by epoxy. In the present case, the epoxy is supplied at a supply point <NUM> and then flows into the distribution channels <NUM>, <NUM>, where it spreads around the entire circumference of the porous material <NUM> or the insert <NUM>. Depending on the viscosity of the epoxy it will also penetrate over a certain depths into the porous material. One of the distribution channels <NUM>, <NUM> is, in the present case, a groove around the circumference and the other one can be a number of recesses or a groove too. An epoxy bridge(s) <NUM> is thereby created. The entrapped air will escape via the porous structure of the insert. Once the epoxy escapes via discharge point <NUM>, the supply can be stopped. To ensure that no epoxy can escape, the supply point <NUM> and the discharge point <NUM> can be provided with a sealing plug.

The epoxy can be replaced by molten metal or a molten alloy. Whereas the metal or the alloy is preferably a material with a low melting point.

<FIG> shows an application with a cover <NUM>. After the porous insert <NUM>, <NUM> has been placed in the recess of a drum <NUM> and is preferably connected to the drum for example via a shrink connection, it can be further secured with a cover <NUM>. The cover is fitted tightly in the recess of a drum and can be secured in the recess as described above. After all inserts are placed and secure in their cavity respectively, the drum can be machined to its final diameter.

<FIG> shows the fixation of the insert <NUM>, <NUM> via a locking pin. After the insert <NUM>, <NUM> is placed in a recess of the drum and is preferably fixed, for example with a shrink connection and preferably joints and cracks are sealed as described above, a hole is drilled preferably over the entire longitudinal length of the drum. A pin <NUM> is then inserted into the hole so that the inserts <NUM>, <NUM> are locked tight fitted in the drum. If needed, the drum can then be machined to its final diameter.

<FIG> shows yet another process how to assemble the inventive forming drum. In the present case, the insert <NUM>, <NUM> is placed from the inside into the sidewall of the drum, against a flange <NUM> machined or casted into the sidewall of the drum. The insert <NUM>, <NUM> is then secured in this position by a locking piece <NUM>, which is also inserted from inside and then fixed to the drum via the above described mechanisms.

In the embodiment according to <FIG>, the insert <NUM>, <NUM> is also placed from the inside against the sidewall of the drum, whereas in the present case, the insert <NUM>,<NUM> comprises a flange <NUM>, preferably in the vicinity of its bottom, which lies against the inner diameter of the sidewall of the drum. The insert <NUM>,<NUM> is secured in this position via a locking piece <NUM>, which is in the present case screwed to the drum by screws <NUM>. The top of the screws can be covered with a cover <NUM> to provide a smooth surface of the drum. The fluid channels <NUM> are, in the present case, machined into the locking piece. It can further be seen, that in the present case there are a multitude of parallel fluid passages <NUM>.

<FIG> shows yet another solution how to fix the insert <NUM>, <NUM> particularly the porous part <NUM> of the insert to the drum. This is in the present case achieved by screws <NUM>. These screws are subsequently covered with a cover <NUM> which also closes the top surface of the porous material <NUM>. Gaps between the porous material and the drum, the porous material and the cover and the cover and the drum can be closed as described above. In the present case, no fluid channels are provided at the circumference of the porous part <NUM>. However, they can be inserted if needed.

<FIG> shows yet another embodiment of the inventive drum. In the present case the insert <NUM>, particularly the porous insert <NUM> will be placed from the inside of the drum in a recess whereas its flange <NUM> lies against a flange, machined into the sidewall of the drum. A locking piece <NUM> secures the insert <NUM>, <NUM> in the drum. The locking piece itself is secured to the drum via screws <NUM>. The hole of the screws can be closed with closing means <NUM>.

<FIG> shows yet another embodiment of the present invention. In the present case, the insert <NUM>, <NUM> is directly screwed to the drum with screws <NUM>. In the present case, the porous material preferably comprises an insert <NUM> which comprises the thread for the screw.

The person in the skilled in the art understands that all means to secure the inserts <NUM>, <NUM> in the drum can be combined. It is particularly preferable to close all gaps and joints by welding, brazing and/or gluing.

In the embodiment according to <FIG>, the product cavities <NUM> of one row <NUM> are not provided as individual inserts <NUM>, <NUM> but at least two product cavities, preferably the entire row of cavities, is provided by one single insert <NUM>. This insert is preferably made at least partially out of the porous material. Support means, here a rib <NUM>, here provided with a fluid passage <NUM>, is located between two product cavities, respectively in order to support the insert <NUM>,<NUM>. Bonding and sealing can be utilized as described above. The support means <NUM> can also extend in a different direction, for example parallel to the longitudinal middle axis of the drum. The single insert <NUM> will be fixed in the drum and is not exchangeable.

In an alternative design as depicted in the subsequent figures, the tube is not made from one member but a multitude of members.

<FIG> shows an embodiment of the tube with an outer member <NUM>, here a thick walled tube and an inner member <NUM>, here a thin walled member. The inserts <NUM>,<NUM> are placed from the inside into the outer member <NUM> whereas a flange <NUM> lies against a flange of the outer member <NUM>. The insert <NUM>, <NUM> is secured in its position by an inner member <NUM> which is in the present case a rolled sheet metal plate. The inner member is preferably secured in its position by a weld with the outer member. The person skilled in the art understands that the inner member can also be secured to the outer member by other means, for example friction-fit or the like. If needed, reinforcement means <NUM>, here rings, can be provided. The fluid passage <NUM> is in the present case located between a recess in the insert <NUM>, <NUM>, a recess in the outer member <NUM> and the inner member <NUM> as can be particularly seen the left hand and right-hand picture of <FIG>.

<FIG> shows also an embodiment of the drum with two coaxial sidewalls, members. In the present case, the drum comprises a relatively thick inner wall member <NUM> and a relatively thick outer wall member <NUM>. The two wall members can be connected via a shrink connection, for example. Porous inserts <NUM> are placed in a recess of the outer member and against the inner member. Fluid passages <NUM> are, in the present case, machined into the inner member whereas also in the present case a multitude of parallel fluid passages <NUM>, which extend over the entire lengths of the tube, are provided. The embodiment according to the present invention also comprises support means <NUM>, here ribs, here between two channels, which support the porous structure mechanically. The porous insert <NUM> further comprises a fluid channel <NUM> through which an air and/or a cleaning fluid flows during production and/or cleaning of the insert <NUM>.

<FIG> shows yet another embodiment of the inventive tube. In the present case, a porous insert <NUM> is placed in a recess in the inner wall member <NUM>, here a thick walled tube. Then, the outer member <NUM>, here a rolled sheet metal plate, will be placed around the inner member. During the fixation process for example a welding process the outer member will be shrunk tight around the inner member and the insert is secured at least in the radial direction, in this case. Four fluid channels <NUM> extend underneath the insert from one front end to the other front end of the drum. Via these channels, a part of the air flows during production to the fluid channels around the insert as depicted by reference number <NUM>, which directs the fluid to the sidewall of the cavity <NUM>. During cleaning, cleaning-fluid flows through all channels <NUM>, <NUM> and cleans the channels.

<FIG> shows yet another embodiment of the present invention. In the present case, a porous insert <NUM>, <NUM> will be placed from the inside in the outer member <NUM>, here a relatively thick walled tube, in a recess of the outer member against a flange <NUM>. Then the inner member a relatively thick walled tube will be places into the outer tube and fixed in the position. This can be done for example via a shrink connection. By using two relatively thick members, the drum will be stiff enough to absorb the forces during production and cleaning. Regarding the fluid channels <NUM>, reference is made to the disclosure according to <FIG>.

Another embodiment of the present invention is depicted in <FIG>. Here the drum consists of two members <NUM>, <NUM> and preferably every product cavity <NUM> is individually machined into the porous inner member <NUM>. This inner member <NUM> is a thick walled tube out of porous material. The outer member <NUM> is a rolled thin sheet metal plate. Both members are fitted tightly to each other as described above. Fluid passages <NUM> are arranged in the inner member <NUM> so that during discharge of the product air will escape uniformly over the area of the product cavity <NUM>. Barriers <NUM> can be provided to prevent that air flow escapes from one row to the other. Barrier <NUM> can be for example created by milling a groove in the porous material. In the present case a hole, that extends over the entire lengths of the drum, is drill and subsequently filled with a non-air permeable material. The inner circumference of the porous tube <NUM> is preferably also sealed, to avoid air leakage. All gaps and joints are preferably sealed by welding/brazing solder to component agents epoxy or the like. In another preferred embodiment, the outer member <NUM> is a metal layer, for example produced by a spraying process, preferably a thermal spraying process. A metal or metal-alloy is sprayed on the surface of the drum.

In the embodiment according to <FIG>, the tube comprises three layers. The intermediate member <NUM> is a thick-walled tube of porous material, here porous metal. The outer member <NUM> is a rolled thin sheet plate and the inner member <NUM> is also preferably a relatively thin metal plate. All members are tightly fitted together, as described above. Fluid passages <NUM> are arranged in the intermediate member so that during discharge of the product air will escape uniformly over the area of the product cavity. The barrier <NUM> can be provided to prevent air flow escape from one row to the other. Barriers <NUM> can also be provided to prevent air flow escape from one cavity to the next in the same row. The barriers can be created by milling a groove in the porous material and fill it with a non-air permeable material. In the present case, the drum comprises reinforcement means, here rings <NUM>, to prevent that the inner member will shrink and pulled inward due to the welding process or during production or cleaning.

<FIG> shows yet another embodiment of the present invention. In this case, the intermediate member <NUM> is a thick-walled tube of porous material, e.g. metal, and the outer member <NUM> is a rolled thin sheet metal plate. The inner member <NUM> is a relatively thick-walled tube from solid material. All members are tightly fitted together as described above. In this embodiment, the fluid passages <NUM> are arranged in the inner member in a way that, during discharge, air will escape uniformly over the area of the product cavity. It is also possible to provide the fluid passages <NUM> in the intermediate member instead of the inner member. Barriers <NUM> can be provided to prevent air escape to other rows. An inner member is provided to prevent that, during discharge of the formed product, air will escape via the intermediate member. Further, it increases the strength and stiffness of the drum.

<FIG> shows yet another embodiment of the inventive food forming drum. In comparison to the embodiment according to <FIG>, to which reference is made, the barriers <NUM> are not parallel to the sidewall of the cavity but shaped around the circumference of the cavity. Additionally, the separation/support walls of the channels do not extend into the outer member, as this is the case in the example according to <FIG>.

<FIG> shows yet another embodiment of the present invention. In this case, a relatively thick-walled, non-porous tube is provided into which recesses are machined, for example milled. Into this recess a porous material <NUM> is deposited which is subsequently, preferably machined, to provide a product cavity and to provide fluid passages <NUM> in the drum. The deposition of the porous material can be done by sintering and/or 3D-metal printing.

In the embodiment according to <FIG>, during discharge of the product and/or during cleaning, the fluid flows only through the porous bottom wall <NUM>.

In the embodiment according to <FIG>, the fluid flows through the bottom wall as well as the sidewalls <NUM>.

In yet another embodiment according to <FIG> the fluid flows through the porous bottom wall <NUM> and through the porous sidewalls <NUM>. The fluid channel <NUM> below the porous insert extends over the bottom as well as at least partially over the sidewalls.

In the embodiment according to <FIG>, the bottom <NUM> and the sidewalls <NUM> have different thicknesses in order to achieve, that the flow through the sidewalls and through the bottom is essentially the same. The person skilled in the art understands, that other flow-pattern can also be desirable.

During filling of the product in the cavities, entrapped air in the product cavity will escape through the permeable walls and through the channel <NUM>. Depending on the porosity of this cavity the channel can be used, during filling, to connect vacuum to the channel <NUM> to evacuate the air which is entrapped in the cavity. During discharge of the formed food product out of the cavity, air under pressure will be connected to the channel <NUM>. This air will flow via channel <NUM> beneath the porous cavity and from there through the porous material and thus loosens the adhesion between the porous material and the food product. Preferably, a porosity will be used which is suitable for most food products to be formed. This depends mainly on parameters like the porosity of the cavities, the used food product, the product height and the diameter of the product. In case of porosity is too large, residues will be left inside the porous material or on top of the porous material after discharging of the formed product. A small porosity has too much flow resistance. However, a certain flow resistance is desired in order to spread the air uniformly over the entire porous surface, which is in contact with the food product.

As already said above and as shown in <FIG>, the inventive drum is place in a food forming apparatus, where it rotates. In case that the drum rotates counter clockwise, the food mass is preferably inserted into the product cavities in a <NUM>-<NUM> o'clock position. The instant, when the discharge product starts based on gravity, is mainly dependent on the structure of the used product. In case, a sticky food product is processed, the discharge of the product and thus the fluid supply has to start earlier in comparison to processing a less sticky product.

In a first embodiment the supply of compressed fluid is already embedded in the cover and drum design. The drum is provided with fluid passages which extend from one end-cap <NUM> to the other end-cap. A cover <NUM>, provided on one side with a fluid supply connection <NUM>, will be positioned during production against the head of the drum. The cover <NUM> is in a stand still position. During production the cover is supplied preferably constantly by a fluid. The discharge of fluid into channel <NUM> starts, when the respective channel <NUM> is at least partially congruent with the recess <NUM> in the cover <NUM>. The duration of the fluid-supply to the channels depends on the length of the recess <NUM> and the speed of rotation of the drum.

In a second embodiment, which is depicted in <FIG>, the cover is again in a stand still position. However, here a valve is opened for fluid supply. The start of the fluid supply can easily be changed preferably on an operating panel by changing the instant when the supply valve is opened. Other than that reference is made to the description according to <FIG>.

<FIG> shows yet another embodiment of the fluid supply. Here the cover is supplied constantly with fluid and the instant of the fluid flow to the channel <NUM> is controlled mechanically. This can be done by rotating the cover. In the lower left hand and right hand figures the change of the start position of the fluid supply to the channel <NUM> is depicted.

In case large products are formed it can be desirable, as depicted in <FIG> to have a multitude of fluid passages <NUM>, here <NUM>. The number of passages will mainly be determined by the air of volume which will be needed to discharge the product. The two channels can be supplied with air simultaneously and/or sequentially.

In <FIG> and <FIG>, the forming of long products like schnitzel is shown. Here, the product cavity <NUM> is also long in circumferential direction of drum <NUM>. To avoid distortion of the formed food product on the outfeed belt <NUM>, the entire formed product should not be discharged at once but in two or more stages. This can be achieved by providing two or more fluid channels. In <FIG> and <FIG> every compartment has its own fluid passage <NUM>, <NUM>, <NUM> and each compartment has its own fluid channel <NUM>, <NUM>, <NUM> each extending from one front end of the drum to the next. Each compartment is connected partially to the formed product. The compartments are divided by dividers <NUM> which are, in the present case part of the drum an in another embodiment part of the insert. The divider can also act as a support as the relatively weak porous material.

During filling of the product entrapped air in the product cavity can escape via the porous part to the fluid channels and from there to the ambient. During discharge of the formed product, first air will be supplied to fluid passage <NUM> and from there to compartment <NUM>. The first part of the formed product then becomes loosed from the porous wall and will be placed on the outfeed belt as shown in the drawing. Then the successes passage <NUM> will be provided with air and in the next step the passage <NUM> will be provides with air in the final step.

<FIG> shows the design of the fluid channels. In general, it is important, that the cleaning fluid passes all passages, channels and porous parts. Due to the resistance of the porous material, the fluid flow will have a low speed. Even then all remaining particles have to be discharged out of the drum. During the cleaning process remaining particles in the channels, compartments and passages should be discharged with a cleaning fluid via the passages to the outside of the drum. Remaining particles in the porous part should be discharged with the cleaning fluids through the porous structure of the outside of the drum. All remaining particles can only be discharged if there are no blind spots. Channels, compartments and passages should be large enough as much as possible straight and provided with roundings to prevent that flow of cleaning a fluid will be blocked.

In the embodiment according to <FIG>, the passages <NUM>, the channels <NUM>, <NUM>, the recess for the insert <NUM> can be included in the cast. As recess <NUM> in eventually the support for the insert <NUM> have to be machined later to the right dimension.

<FIG> show yet another embodiment of the inventive food forming drum <NUM>. In the present case, the drum <NUM> comprises one groove per row of cavities, which extends over the entire lengths of the drum. In the present case, the cross section of the groove is dove tailed. Inserts with a corresponding diameter, in the present case one insert per product cavity, can be inserted from a frontend, preferably each frontend, into the groove. The inserts <NUM> are at least partially made from a porous material and the cross section is shaped such, that there is a form-fit between the groove and each insert, respectively, due to the dove tailed cross section. Preferably, each row comprises one or more pressure elements <NUM>, which pushes the inserts <NUM> towards the circumference of the drum and thus reduces the gap between the insert and the surface of the drum. The gap between the insert and the drum can be closed as presented above. A fluid passage <NUM> is provided between the insert <NUM> and drum <NUM>. The joint length of all inserts is preferably longer than the longitude extension of the drum. After the inserts have been placed into the drum, the inserts can be pressed into against the drum by means of one or more pressure element(s) and one or two end cap(s) is/are provided at least at one front-end of the drum.

In the embodiment according to <FIG>, only one insert per row is provided which comprises all product cavities of this row respectively. However, it is also possible to have a multitude of inserts per row, whereas each insert may comprise more than one cavity.

<FIG> shows another embodiment of the inventive drum. The drum comprises an inner member <NUM> and an outer member <NUM>. In the preset case, each row of cavities (here fife) comprises a multitude of porous inserts <NUM>, placed in parallel along the axis of the drum. The porous inserts <NUM> will be placed from the inside of the outer member <NUM>, here a relatively thick walled tube, into a recess of the outer member. After insertion each insert lies at least partially against the inner circumference of the recess, respectively. In the present case, the cross section of the insert is at least partially dove tailed and its outer circumference lies at least partially against the inner circumference of the recesses in the outer member. Each recess extends through the entire outer member and narrows at least partially from the inner diameter to the outer diameter of the outer member <NUM>. The inserts can be round, rectangular, square, oval or the like. One insert can comprise one or more cavities. The inserts can be connected to the outer member by material bonding. A gap between the porous insert and the outer member can be closed by means as described above. After the porous inserts have been placed in recesses of the outer member, respectively, the inner member <NUM> is inserted into the outer member and fixed to the outer member. The inner member <NUM> preferably fixes the inserts <NUM> in their respective position in the outer member. In the present case, the inner member <NUM> has a slot <NUM> which extends over its entire length. The diameter of the inner member <NUM> is preferably larger than the inner diameter of the outer member <NUM>. For insertion, the slot <NUM> of the slightly oversized inner member is elastically compressed, so that the diameter of the inner member <NUM> reduces. Then the inner member <NUM> is placed in the outer member <NUM> and the elastic compression is released. Due to the spring-like force of the inner member expands and is pressed against the outer member <NUM> and/or the inserts <NUM>. After insertion of the inner member, the slot <NUM> may be secured against compression and/or, the slot can be widened to increase the pressure of the inner member against the outer member and/or the inserts. The inner member <NUM> is, in the present case, thick walled tube.

The inner member <NUM> comprises at its circumference a multitude of channels, in the present case two channels per row of cavities, which preferably extend over the entire length of the inner member. The inserts may be supported by a support member provided at the outer circumference of the inner member, here located between two channels, which takes over part of the load, for example during filling of the cavities in the porous inserts. The person skilled in the art understands that the channels can also be provided at the inner circumference of the outer member <NUM>, as described above.

After the inserts <NUM> have been inserted and fixed to the outer member <NUM>, the outer diameter of the drum may be smoothened.

Reference is also made to the disclosure regarding <FIG>.

<FIG> show yet another embodiment of the present invention. In this embodiment, the inventive drum <NUM> comprises an inner member <NUM>, here a drum, which is for example made from stainless steel. This inner member, the drum, comprises at least one, preferably a multitude of longitudinal ribs <NUM>, which preferably extend radially from the circumference of the inner member <NUM> and which preferably extend over the entire length of the drum and more preferred until the outer circumference of drum <NUM>, as can be seen from <FIG>, <FIG>. The inner member <NUM> and the rib(s) is/are preferably one piece. Between two longitudinal ribs, respectively, one or more inserts <NUM> are arranged, which are at least partially, preferably entirely made from a porous material, as previously described. The cross section of each insert is preferably the segment of a circle. Alternatively, the cross section can be dovetailed. Each insert <NUM> can, for example, sintered in a mould which is provided with a curved inner- and outer surface. Subsequently, the front ends of the inserts are preferably machined, preferably grinded. During this process step, the shape of the one or more front ends can be changed, if desired, and/or the porous structure of the front ends can be closed to create a strong bonding connection. Preferably, all four front ends of each segment are closed. Each insert may comprise one or more groove(s) and/or fluid-channel(s) as previously described. Each of two opposing front ends <NUM> of each insert is preferably placed against a rib <NUM>. Each rib preferably comprises two dead stop <NUM>, here a shoulder, for the insert. After the insert has been placed into the recess between two ribs <NUM>, preferably one edge of each front end <NUM> lies against the dead stop <NUM>, so that each insert is in a clearly defined position, as can be best seen from <FIG>, <FIG> and <FIG>. Between the inside of insert <NUM> and inner member <NUM>, the inventive drum <NUM> preferably comprises one or more fluid channel(s) <NUM>, for example to vent the inserts and/or to discharge a fluid through the porous insert <NUM>. Each channel <NUM> can be machined into the inner member <NUM> and/or into the insert <NUM>. In the present case, the dead stops <NUM> are designed such, that a distance is left between the circumference of the inner member <NUM> and the inside of the insert <NUM>, which serves as the fluid channel <NUM>. This fluid channel preferably extends from one front end of the insert to the other. As can seen particularly from <FIG>, the inner member <NUM> and/or the insert <NUM> may comprise support means <NUM>, here one or more rib(s), for the insert <NUM>. The support means <NUM> may also be used to define a fluid channel. The distance between two ribs <NUM> is preferably slightly larger than the distance between the two front ends <NUM>. This simplifies the insertion of the insert between the ribs <NUM> and/or allows space for a bonding material, for example a glue or a soldering material.

Prior to inserting the insert between two ribs <NUM>, the surface of the insert <NUM> is preferably, at least partially covered with a soldering film, for example as previously described, which is bonded to the insert <NUM>. This film can be used to fix the insert <NUM>, preferably irreversibly, at the inner member <NUM> and/or to closed the surface of the insert, where needed.

Each front end <NUM> of the insert <NUM> is preferably rigidly and irreversibly connected with a rib <NUM>. This connection is preferably, at least essentially fluid-tight. The connection between the insert <NUM> and the rib <NUM> is preferably executed with flux-free soldering, as described above. However other bonding and/or sealing means, for example as described above, can be used additionally or alternatively. In order to improve the soldering, prior to insertion of the insert between two ribs <NUM>, a solder material, for example a paste can be inserted into a longitudinal groove <NUM> in rib <NUM>. The person skilled in the art understands that the grooves <NUM> can be alternatively or additionally in the insert <NUM>. Grooves <NUM> can also be provided in end caps <NUM> and <NUM> and in distance piece <NUM>.

As can be seen, for example, from <FIG>, the insert <NUM> between two ribs <NUM> can be a single piece (<FIG>) or a multitude of pieces (<FIG>). In case of a multitude of pieces, two pieces can be separated by a distance piece <NUM>, respectively (<FIG>). This distance piece can be a film or a sheet. Two inserts can be connected by the distance piece <NUM>. However, a multitude of inserts can also be placed directly adjacent as depicted in <FIG>.

When using flux-free soldering as the bonding technique between the insert <NUM> and the ribs <NUM>, the inserts and the end cap and/or between the inserts themselves, the distance between the parts to be connected is preferably < <NUM>,<NUM>, more preferably <<NUM>,<NUM>, here app. <NUM>,<NUM>. Each solder joint will be filled preferably with solder film/foil. If needed, additional solder material, for example solder paste in a reservoir <NUM> between two parts <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be provided.

After the inventive drum is assembled, it is heated, for example in an oven and the solder material is liquefied and/or its viscosity reduces to capillary forces the solder material spreads into regions with insufficient coverage with solder material. After the drum <NUM> exits the heater, it is cooled down and the inserts <NUM> are irreversibly bonded with the inner member, i.e. they cannot be removed from the inner member without destruction.

If needed, support ribs <NUM> can be placed between each product cavity <NUM> in one row and/or in longitudinal direction preferably parallel to ribs <NUM>, as can be seen from <FIG>.

The joint length of the, or all insert(s) in one row is preferably longer than the length of the inner member <NUM>. After the inserts <NUM> have been placed at the inner member, the inserts in one row are preferably tightened and secured, i.e. clamped in longitudinal direction, by two end caps <NUM>, <NUM>.

As one of the final steps, drum <NUM> is preferably machined into its final diameter. Thereby, the pores on the surface of the inserts are preferably closed. The product cavities <NUM> can be provided prior or after the inserts <NUM> are fixed to the inner member <NUM>. However, preferably, the cavities are inserted into the drum in a final machine step.

<FIG> depicts an example in which the thickness tb of the bottom <NUM> is smaller than the thickness ts of the sidewall <NUM>. When fluid via passage <NUM> is directed to fluid channel <NUM> this fluid will first enter the product cavity <NUM> via the bottom <NUM> and subsequently via sidewall <NUM> due to the higher flow-resistance of the sidewall and/or the longer distance this fluid has to pass.

Reference is now made to <FIG>. The product cavity within the porous material can be produced, for example by milling. The flow of fluid through the bottom <NUM> or the sidewall <NUM> can be, for example, influenced by the tool which will be used (type of milling cutter, material milling cutter, number of cutting edges, angle cutting edge, etc.) and/or by a milling parameter (cutting speed, feed rate, etc.). By machining the sidewall <NUM> by method1 (<NUM>) and the bottom <NUM> by method <NUM> (<NUM>) the surface and permeability of the sidewall and the bottom will be different which will result in different flow characteristics. Each method, for example, closes the pores on the surface of the sidewall and the bottom differently. Preferably, method <NUM> and <NUM> is milling, grinding, EDM and/or polishing. Preferably, the sidewall has a lower permeability than the bottom.

<FIG> shows a cavity, whereas the bottom is made from a material with a different porosity than the material of the sidewall. Again, this results in a phase lack between the ejection of a fluid through the bottom and through the sidewall. Preferably, the porosity of the bottom material is higher than the porosity of the sidewall material.

<FIG> shows an example with a multitude of passages; one separate passage <NUM> for the bottom and one separate passage <NUM> for the sidewall.

When fluid is directed to both passages <NUM> and <NUM> at the same time this fluid will enter the product cavity at the same time from the bottom and from the sidewall. When fluid is directed first to passage <NUM> which is connected to the porous structure of the sidewall and some time later to passage <NUM> which is connected to the porous structure of the bottom, the fluid will enter the product cavity first via the sidewall. When fluid is directed first to passage <NUM> which is connected to the porous structure of the bottom and some time later to passage <NUM> which is connected to the porous structure of the sidewall the fluid will enter the product cavity first via the bottom. When processing a sticky mass, the formed food product will stick to the cavity due to the adhesion forces between product and the sidewall. By using different fluid pressures this problem can be solved. First fluid with a relatively low pressure can be directed to passage <NUM> to eliminate adhesion forces between formed product and bottom wall. Then fluid with a relatively low pressure can be directed to passage <NUM> to eliminate adhesion forces between formed product and sidewalls. Then fluid with higher pressure can be directed to passage <NUM> (bottom wall) to remove product from cavity. The person skilled in the art understands, that all features of the examples can be combined among each other and new claims can be worded.

Claim 1:
Food forming drum (<NUM>) comprising a multitude of rows (<NUM>) of porous product cavities (<NUM>, <NUM>, <NUM>), each row (<NUM>) comprising one or a multitude of porous product cavities (<NUM>, <NUM>, <NUM>) and a first and a second front end (<NUM>, <NUM>) and fluid channels (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) in the longitudinal direction of the drum each fluid channel (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) connecting one row (<NUM>) of porous product cavities (<NUM>, <NUM>, <NUM>) fluid-wise, wherein a sidewall (<NUM>, <NUM>) and a bottom (<NUM>, <NUM>) of the porous cavity have different flow-resistances regarding the fluid flow of the fluid to remove the formed food product from the cavity (<NUM>, <NUM>, <NUM>), characterized in, that more pores on the surface of the porous material at the sidewall are closed than pores on the surface of the porous material at the bottom of the porous cavity.