WO2016068697A1

WO2016068697A1 - Method of layered object manufacturing, sheet element, object manufacturing device, and object

Info

Publication number: WO2016068697A1
Application number: PCT/NL2015/050742
Authority: WO
Inventors: Ernst Jan BOS
Original assignee: Stichting Vu-Vumc
Priority date: 2014-10-27
Filing date: 2015-10-27
Publication date: 2016-05-06
Also published as: NL2013687B1

Abstract

The present invention provides a method of layered object manufacturing using multiple sheet elements each having a predetermined dimension, wherein the sheet elements comprise first interlocking elements configured to interlock with at least a first further sheet element arranged at a first side of the sheet element, and second interlocking elements configured to interlock with at least a second further sheet element arranged at a second side of the sheet element, wherein the second side is opposite the first side. The method comprises stacking the multiple sheet elements on top of each other, wherein the first interlocking elements of a first one of the multiple sheet elements interlock with the second interlocking elements of a second one of the multiple sheet elements arranged at the first side of the first sheet element, and the second interlocking elements interlock with first interlocking elements of a third one of the multiple sheet elements arranged at the second side of the first sheet element. The invention also provides a sheet element, an object manufacturing device, and object constructed with the method.

Description

Method of layered object manufacturing, sheet element, object manufacturing device, and object.

The present invention relates to a method of layered object manufacturing and a sheet element to be used in layered object manufacturing. The invention further relates to an object manufacturing device and an object obtained by layered object manufacturing. Various systems exist to create 3D models, for example rapid prototyping from layers of material. In stereo-litography a liquid resin is solidified using photo-polymerisation by ultraviolet light. Selective laser sintering (SLS) is a method in which layers of powder are bonded by heat provided by a laser. This method allows the use of various materials, including metal. Fused deposition manufacturing (FDM) deposits strands of extruded viscous material in an overlaying pattern to create a 3D object.

In an embodiment of layered object manufacturing (LOM) layers of a specific material in the form of sheets are laminated on each other to create a stacked shape. The individual sheets can be pre-formed to create the desired 3D model or can be trimmed during and after the laminating process. Fusion of the sheets occurs through using a binder material or thermo-, photo-, or chemical binding of the sheet surfaces themselves.

Each technique offers different advantages and has a range of optimal materials to create a 3D construct with. Creating a construct with a broad selection of materials (metal, ceramic, plastics) is difficult because most of the components require different disciplines to fuse the material and form shapes.

For bioengineering applications, it is desired to combine a number of materials including cells or other biological materials.

LOM allows the use of a large variety of different materials as it consists of stacking and not actually fabricating the individual material layers. The binding process of especially different materials is dependent however on an appropriate binder method and generally consists of a binding agent applied between layers. The selection of biocompatible or bioresorbable binders is limited. Also the strength of the available binders to adhere different layer materials is limited.

Thermo-, chemical- or photo-polymerisation fusion of these layers is generally impossible to combine with cells due to viability issues and these methods are often limited to a single material. Therefore, it is desirable to provide a method that enables 3D object manufacturing in a biocompatible and cell friendly matter whilst being of sufficient strength to create a durable 3D construction. More generally, it is desirable to provide a relatively fast method of layered object manufacturing that provides a strong and durable construction, or at least to provide an alternative method of layered object manufacturing.

The present invention provides a method of layered object manufacturing, comprising the steps of:

providing multiple sheet elements each having a predetermined dimension, wherein the sheet elements comprise first interlocking elements configured to interlock with at least a first further sheet element arranged at a first side of the sheet element, and second interlocking elements configured to interlock with at least a second further sheet element arranged at a second side of the sheet element, wherein the second side is opposite the first side,

stacking the multiple sheet elements on top of each other, wherein the first interlocking elements of a first one of the multiple sheet elements interlock with the second interlocking elements of a second one of the multiple sheet elements arranged at the first side of the first sheet element, and that the second interlocking elements interlock with first interlocking elements of a third one of the multiple sheet elements arranged at the second side of the first sheet element.

According to this method the sheet elements are mechanically connected to each other by the first and second interlocking elements. This mechanical interlocking provides a strong and reliable connection between layers of the 3D object constructed with the method, without the need of detrimental binding systems such as (chemical) binders, UV radiation or thermo- polymerisation.

Preferably, adjacent sheet elements of a stack of sheet elements are interlocked with each other, but in alternative embodiments, a first sheet element can be interlocked with a second sheet element, while one or more further sheet elements are placed between the first sheet element and the second sheet element. Also, one sheet element may comprise interlocking elements to directly interlock with three or more sheet elements placed on top of each other.

The first and second interlocking elements may have any suitable shape. Preferably, the first and second interlocking elements are formed to create a permanent connection between two sheet elements. The first and/or second interlock elements may for example comprise hook elements, configured to interlock with one or more locking openings in another sheet element. Correspondingly, the first and/or second interlocking elements may comprise locking openings to receive hook elements of other sheet elements.

The hook elements may for example be formed as click fingers having a locking rim. These click fingers may extend from a base construction in a direction at least partially perpendicular to a main plane of the base construction and may be flexible in a bending direction substantially parallel to the main plane, such that by elastically bending the clicking finger in the bending direction the hook element can pass an edge of a locking opening, and snap back into a relaxed state in which the hook element catches the edge of the locking opening.

The sheet elements are preferably prefabricated. The use of prefabricated interlocking sheet elements allows for fast and consistent manufacturing of 3D constructs. During

construction of a 3D construct the sheet elements can be used to quickly add layer to the construct by subsequently placing and interlocking sheet elements on top of each other, while placing a sheet element on the stack comprises the interlocking of the first and second interlocking elements of two sheet elements. The 3D construct may increase in strength as more layers of sheet elements are stacked and interlocked.

The sheet elements can be made of any suitable material, such as plastics, ceramics or metal. The type of material also depends on the application of the 3D object constructed with the method. It is remarked that also different types of sheet elements, for example sheet elements of different materials may be combined in a single stack of sheet elements.

The sheet elements may also have any suitable design. Parameters such as porosity of the material may also be selected in dependence of the application.

The material and design of the sheet elements may be used to form a rigid body of stacked and interlocked sheet elements, but also to form a body having a certain degree of flexibility.

The sheet elements may be designed to form any desired shape, for example a curved shape, by stacking and interlocking sheet elements of predetermined dimensions in a predetermined mutual positional relationship.

The manufacturing of the sheet elements can be done in various ways depending on the material type and the desired dimensions. Stereo-litography can for example be used to create fine resolution first and/or interlocking elements matrices and/or thin sheet elements. SLS can be used to create intricate metal or ceramic sheets designs. More conventional methods such as press moulding or laser pattern cutting and template pressing can also be used to create sheet elements, for example for larger sheet elements or sheet elements with larger-sized first and/or second interlocking elements.

The height of the sheet elements and the resulting layer height in the 3D object to be constructed with the sheet elements may vary in dependence of the application of the 3D object. For example, a height of less than a millimeter may be used in application requiring a small resolution, while heights of more than a centimeter may be used in large scale 3D objects.

In an embodiment, the method comprises covering the first side or the second side of the or more of the multiple sheet elements at least partially with a layer of filling material. The sheet elements may be configured to receive a filling material between them. This filling material may be part of a prefabricated sheet element, or the filling material may be deposited on a sheet element before placing another sheet element on top of it.

In an embodiment, the filling material comprises cells or other biological material. The use of stacked interlocking sheet elements in layered object manufacturing is in particular suitable for use in a method in which cells or other biological material is to be used. For example, in medical implants and in particular bio-scaffolds it is desirable to introduce cells or other biological material in a 3D object.

Conventional layered object manufacturing methods are not very suitable to construct 3D objects with cells or other biological material as these methods comprise thermo-, chemical- or photo-polymerisation fusion of layers to each other. These processes have a large impact on viability of cells, but also on the possible composition of the bioscaffolds. A bonding agent, such as glue, has always a limiting factor and hampers incorporation of other biomaterials, for example cells hydrogel. Mechanical interlocking of sheet elements has a very limited impact on viability of cells. The liquid, gel or other material containing cells between layers is only subject to minor manipulation when connecting the sheet elements to each other with the mechanical interlocking system.

In an embodiment, the step of providing multiple sheet elements each having a predetermined dimension, comprises:

determining the desired dimension for each sheet element, and

separating the respective sheet element with the desired dimension from a base sheet element.

The method of the invention can be carried out in a quick and efficient way when use is made of larger base sheet element from which sheet elements of a predetermined size are separated. The large sheet elements may for example be provided as larger sheet elements having dimensions of at least a construction platform of an object manufacturing device configured to carry out the method of layered object manufacturing. The base sheet element may be provided as flat elements or rolled up.

The separation of the sheet elements of predetermined size may for example comprise cutting, laser cutting, milling, etc.

In an embodiment, the sheet elements may be provided with separation facilitating lines configured to facilitate separation of a part of sheet element, such as grooves or lines with smaller holes, or separation indication lines configured to indicate a line for separation.

These separation facilitating lines and/or separation indication lines may help a user to manually separate a sheet element of desired dimension from a base sheet element, in particular in home and large resolution applications. In such manual application, the user has to determine the desired dimension of the sheet element and separate the sheet element of desired dimensions from the base sheet element.

In an alternative embodiment, a control device and a separating device of an object manufacturing device may be used to determine the desired dimensions of the sheet element on the basis of the 3D object to be constructed, and the intended location of the respective sheet element in the 3d object, whereby the separating device will separate the sheet element with the desired dimensions from the base sheet element. The control device may comprise software to determine the optimal layer structure of stacked sheet elements and to determine the size of the sheet elements needed for this optimal layer structure of stacked sheet elements.

In an embodiment, the method comprises a step of 3D printing of 3D printing material, such as thermoplastics, photopolymers, ceramics or wax on or in the stacked multiple sheet elements. Any suitable 3D printing technique, such as fused deposition moulding (FDM), may be used in combination with the stack of interlocked sheets to provide an object having a stack of interlocked sheet elements and 3D printing material, for instance layers of 3D printing material in or on the stack of interlocked sheet elements.

In an embodiment, the method comprises a step of providing a skin layer around the stacked multiple sheet elements.

In known 3D printing techniques printing the infill, i.e. the interior part of 3D objects to ensure strong mechanical properties takes up a significant amount of time in production; for example in many prints 75% of the material and time is used for infill, especially in large objects. The sheet elements can be used as a pre-fabricated infill for a 3D object. The stack of sheets can provide a strong construction. By using a 3D printing technique, such as FDM, during or after the construction of the stack of sheet elements a skin layer can be printed on the stack of sheet elements forming the infill of the 3D object to be constructed. The skin layer may cover the whole stack of sheet elements, but also a part thereof.

In an embodiment, the first interlocking elements of the first sheet element correspond to the first interlocking elements of the second sheet element and the third sheet element, and wherein the second interlocking elements of the first sheet element correspond to the second interlocking elements of the second sheet element and the third sheet element. In such embodiment each sheet element comprises the same first and second interlocking elements, for example interlocking extensions as first interlocking elements and locking holes as second interlocking elements. As a result, all sheet elements may placed on top of each other in an interlocking manner.

In alternative embodiments sheet elements having different first and second interlocking elements may be provided. For example a first type of sheet elements having locking extensions at both sides, and a second type of sheet elements having only locking holes. By stacking alternately sheet elements of the first and second type, a stack of mechanically interlocked sheet elements may be created.

In an embodiment, the first interlocking elements are arranged in a first pattern and the second interlocking elements are arranged in a second pattern, wherein the first pattern and the second pattern correspond.

The first pattern of the first interlocking elements and the second pattern of the second interlocking elements may be designed to be coupled in a fixed relationship, in which each of the first interlocking elements of the first pattern to be coupled with a second interlocking element is aligned with a specific one of the second interlocking elements. In such embodiment, adjacent first interlocking elements of the first pattern are coupled to adjacent second interlocking elements of the second pattern.

In another embodiment, the first interlocking elements and the second interlocking elements may more randomly couple to each other. For example, two adjacent first interlocking elements are coupled to two second interlocking elements that are not adjacent to each other. In an embodiment, the first interlocking elements and the second interlocking elements may be hooks and loops, respectively, that are designed to lock into each other when the sheet elements on which the first interlocking elements and the second interlocking elements are provided, are placed on top of each other.

In an embodiment, the sheet elements comprise spacer elements to hold the stacked and interlocked sheet elements in a spaced relationship with respect to each other. It is desirable to maintain the sheet elements in a spaced relationship, whereby the first and second interlocking elements engage with each other to provide the mechanical coupling between two sheet elements. The space between the two sheet elements saves out material and can be used to provide filling material between two sheet elements. The filling material may be more flexible as the main strength of the construction is provided by the stack of interlocked sheet elements.

In an embodiment, the spacer elements are formed by the first and/or second interlocking elements. The spacer elements may be formed by separate elements, but may also be formed by a part of the first and/or second interlocking elements.

The invention also provides a stackable sheet element for use in layered object manufacturing, comprising

first interlocking elements configured to interlock with a first further sheet element arranged at a first side of the sheet element, and

second interlocking elements configured to interlock with a second further sheet element arranged at a second side of the sheet element, wherein the second side is opposite the first side.

Such sheet element is suitable for a method of layered object manufacturing using mechanical interlocking to couple layers to each other.

In an embodiment, the sheet element comprises:

a base construction extending in a first plane,

wherein the first interlocking elements comprise locking projections extending in a direction at least partially perpendicular to the first plane, wherein a first end of the locking projections is connected to the base construction and a second end opposite to the first end comprises a hook, and

wherein the second interlocking elements comprise locking openings provided in the base construction and configured to receive locking projections of an other sheet element in an interlocking manner.

By forming hooks, i.e. an element than locks with an edge of a locking opening, a simple and reliable connection between the first and second interlocking elements can be obtained.

In an embodiment, the second end of the locking projection or a part thereof is elastically movable in a direction substantially parallel to the first plane to allow the hook to pass a locking edge of a locking opening of a sheet element to be interlocked with the sheet element.

In an embodiment, the first interlocking elements are arranged in a first pattern and the second interlocking elements are arranged in a second pattern, wherein the first pattern and the second pattern correspond. The first pattern of the first interlocking elements and the second pattern of the second interlocking elements may be designed to be coupled in a fixed relationship. In another embodiment, the first interlocking elements and the second interlocking elements may more randomly couple to each other.

In an embodiment, the first interlocking elements are hooks and the second interlocking elements are loops, that may be designed to randomly lock into each other when the sheet elements on which the first interlocking elements and the second interlocking elements are provided are placed in a stack.

The invention further provides an object manufacturing device, comprising:

a sheet element supply for holding one or more sheet elements configured to

mechanically interlock, for example sheet elements as claimed in any of the claims 10-15,

a construction area,

a positioning device configured to move a sheet element between the supply of sheet elements and the construction area, and to position the sheet element in a desired location within the construction area,

a control device configured to control the positioning device, wherein the control device is configured to consecutively take sheet elements from the supply of sheet elements and position the sheet elements in a stacked and interlocked relationship in order to form an object.

In an embodiment, the object manufacturing device comprises a filling material deposit device configured to cover at least one side of a sheet element at least partially with a layer of filling material.

In an embodiment, the object manufacturing device comprises a separating device to separate a sheet element with a desired dimension from a base sheet element having a larger dimension.

In an embodiment, the object manufacturing device comprises a 3D printing head configured to print printing material, such as thermoplastics, photopolymers, ceramics or wax, in combination with the stacked and interlocked sheet elements to form the object.

The invention further provides an object manufactured using multiple sheet elements as claimed in any of the claims 10-15, wherein the multiple sheet elements are stacked in an interlocking manner to form a single body. The single body may be a rigid body but may also be designed to have some flexibility in dependence on the intended application of the object.

In an embodiment, the object is a medical implant, such as a bio-scaffold. A bio-scaffold is a 3D object of biocompatible and/or bioresorbable materials having a 3D structure comparable to the implant tissue area. This bio-scaffold may be provided in order to promote, after implantation, tissue regeneration and injury recovery. The bio-scaffold may be seeded with native differentiable cells and cell adhesion proteins in order to encourage cell adhesion and tissue regeneration. The bio-scaffold is advantageously also consistently porous, which further promotes cell adhesion and differentiation at a controlled rate.

The cells and cell adhesion proteins may be provided as a layer of filling material arranged between two or more sheet elements. Also other filling materials may be provided.

In an embodiment, the object comprises a part of 3D printed material, for example a skin layer of 3D printed material at least partially enclosing the stack of interlocked sheet elements. The stack of interlocked sheet elements may be used as an infill, whereby a skin layer is printed, for example to obtain a smooth and/or fine outer surface of the 3D object. By using a stack of sheet elements as infill, a strong 3D object can be created in a quick manner and using a layered object manufacturing method.

Further advantages and characteristics of the invention will be elucidated by description of embodiments of the invention. In this description reference will be made to the accompanying drawings in which:

Figure 1 depicts a perspective view of a first embodiment of sheet elements according to the invention;

Figure 2 depicts a side view of a the sheet elements of the embodiment shown in Figure

1 ;

Figure 3 depict a base plate for formation of a second embodiment of a sheet element according to the invention;

Figure 4 depicts a side view of the sheet element formed from the base plate shown in Figure 3;

Figure 5 depicts a perspective view of stack of sheet elements of the embodiment shown in Figure 3;

Figure 6 depicts a side view of the stack of sheet elements shown in Figure 5;

Figure 7 depicts another embodiment of a sheet element of the invention; and

Figure 8 depicts schematically an object manufacturing device according to an embodiment of the invention. The invention relates to a method of layered object manufacturing in which sheet elements are used to at least partially form an object. The sheet element to be used in this method are arranged in a stack of sheet elements that are coupled to each other.

Figures 1 and 2 depict a stack 1 of three sheet elements 2 and an additional separate sheet element 2 above the stack 1 of sheet elements 2.

The sheet element 2 comprises a plate shaped base construction 3, a first pattern of interlocking extensions 4 and a second pattern of locking openings 5 in the base construction 3. The base construction 3 extends in a first plane. Each interlocking extension 4 comprises a pair extension parts 6 that each extend from the base construction 3 in a direction substantially perpendicular to the first plane. A first end of each extension part 6 is connected to the base construction 3 and each second end, opposite to the first end comprises a hook 7. The extension part 6 is configured to be arranged through a locking opening 5 of an adjacent sheet element, whereby the opposed hooks 7 of the pair of extension parts 6 are arranged over the edge of the locking opening 5 such that the sheet elements are interlocked.

The first pattern of the of interlocking extensions 4 and the second pattern of locking openings 5 correspond but are shifted in the direction of the first plane, such that two sheet elements 1 can be placed on top of each other such that a substantial part of the interlocking extensions 4 of one sheet elements lock with the hooks 7 in the locking openings 5 of the other sheet element 2.

The hooks 7 each comprise a locking rim 8, a slanting surface 9, and a spacer surface

10. The locking rim 8 is provided to catch the edge of the locking openings 5.

In the shown position of the second ends of the extension parts 6, the distance between the locking rims 8 is larger than the dimensions of the locking opening 5. This ensures a proper coupling of the locking rims 8 of the hooks on the opposite edges of the locking opening 5. However, in this position the interlocking extension 4 cannot be moved through the locking opening 5, as the dimensions of the interlocking extension 4 are larger than the locking opening 5. To make introduction of the locking extensions 4 into the locking openings possible, the second ends of the extension parts 6 are movable in a direction substantially parallel to the first plane from a first relaxed state towards each other in order to decrease the distance between the locking rims 8 of the hooks 7.

The slanting surfaces 9 of the hooks 7 are provided to move the second ends of the extension parts 6 towards each other when the interlocking extension 4 is pressed into a locking opening 5. While the hooks 7 are moved into the locking opening 5, the slanting surfaces 8 also facilitate the alignment of the first pattern of interlocking extensions 4 of a first sheet element with the second pattern of locking openings 5 in a second sheet element that is coupled with a first sheet element.

The side view of Figure 2 shows more clearly the mechanical interlocking between the sheet elements 2 in the stack 1 of sheet elements 2. The hooks 7 of the interlocking extensions 4 of the lower two sheet elements 2 extend through the locking openings 5 of the adjacent sheet element placed on top of the respective sheet element 2. Further, it can be seen that the spacer surfaces 9 of the hooks 7 of the lower sheet element 2 of the stack 1 may serve as a spacer element to maintain the upper sheet element 2 of the stack 1 at a minimal distance from the middle sheet element 2 of the stack 1.

The base construction 3 comprises holes 1 1 that have a smaller diameter than the locking openings 5. In this embodiment the diameter of the holes 11 is also smaller than the diameter of the spacer surfaces of an interlocking extension to avoid the risk that one or more interlocking extensions 4 will enter the holes 1 1 .

These holes 1 1 may have several functions. The holes 1 1 may be used to cooperate with a positioning device to enable the positioning device to take up the sheet element 2 and position it at a desired location, for example as a new sheet element 2 on a stack of sheet elements 2. The holes 1 1 may also be used as separation facilitating lines that can be used to facilitate separation of a sheet element 2 with desired dimensions from a larger sheet element. The holes 1 1 may indicate to the user where to cut the sheet element to separate a part thereof, but also may be used for placing a cutting tool, such as a cutting saw there through. The holes 11 may also increase the porosity of the stack of sheet elements in designs where porosity of such construction is desired.

The sheet element 2 may be made of any suitable material and by any suitable method, for example stereolitography or SLS.

The advantage of the sheet elements 2 is that without the need of thermo-, chemical- or photo-polymerisation fusion of layers, a 3D construction can relatively quickly be built up using pre-fabricated sheet elements 2 that mechanically interlock when pressing the sheet elements 2 on each other. The sheet elements 2 of desired dimensions may be easily separated from base sheet elements. These base sheet elements 2 may be substantially larger than the sheet elements 2 shown in Figures 1 and 2 so that multiple sheet elements 2 used for a 3D object can be separated from the base sheet element. In an alternative method, the sheet elements 2 are prefabricated with the dimensions with which they are used in the 3D object to be constructed.

The sheet elements 2 may in particular be used in layered object manufacturing to construct a relatively strong scaffold of spaced sheet elements 2. The spaces between sheet elements 2 in a stack 1 of sheet elements can be filled with filling material. This filling material may for example be a liquid, gel or other viscous material possibly containing cells or other biological material.

Figure 3 shows a base plate 20 to form an alternative embodiment of a sheet element 21 according to the invention. The base plate 20 is made of metal and a pattern of shapes is cut into the base plate, for example by laser pattern cutting. Interlocking extensions 22 are cut out. A first end of the interlocking extensions 22 is connected to the rest of the base plate 20 while a second end forms a free end. As a result, the interlocking extensions 22 can be folded out of the plane of the base plate 22. The rest of the base plate 20 forms a plate shaped base construction 23 comprising locking openings 24.

Figure 4 shows a side view of the sheet element 21 formed from the base plate in which the interlocking extensions 22 are folded out to a direction partially perpendicular to the first plane such that the interlocking extensions are arranged in a first pattern to cooperate with a pattern of locking openings 24 of a second sheet element arranged on top of the sheet element 21 . In this configuration, the sheet elements 21 that can be placed on top of each other with an interlocking connection all have the same arrangement of interlocking extensions 22 and locking openings 24.

The interlocking extensions 22 comprise hooks 25 to be placed over the edge of the locking openings 24, slanted surfaces 26 forming an arrow shaped top end and spacer elements 27.

As can be seen in Figure 3, the locking openings 24 have a substantially triangular shape. The angle of the folded out interlocking extensions 22 with respect to the base construction 23 is selected such that in the relaxed state the free end of the interlocking extensions is aligned with the smaller sides of the triangular locking opening 24.

When two sheet elements 21 are placed on top of each other in an aligned manner and pressed against each other, the slanted surfaces 26 will enter the locking openings 24 at the smaller side until the slanted surfaces 26 hit at both sides the edge of the locking opening 24. When the sheet elements 21 are pressed further towards each other the slanted surfaces 26 will be pressed towards the larger side of the triangular locking opening 24, therewith moving the free ends of the interlocking extensions 22 in a direction substantially parallel to the plane of the base construction. When the hooks 25 have reached a location of the locking opening 24 where its width is larger than the dimensions of the hooks 25, the hooks 25 can move through the locking openings 24 and the interlocking extensions 22 can move back into the relaxed state. As a result, the hooks 25 will extend over the edges of the locking opening 24, and a permanent interlocking between the two sheet elements is obtained.

Figures 5 and 6 show two sheet elements in the interlocked state where all extension elements 22 of the lower sheet element are mechanically locked in the locking openings 24 of the upper sheet element.

The spacer elements 27 ensure that the sheet elements 21 are held in a spaced relationship. To avoid that the spacer elements 27 inadvertently enter the locking openings 24, the dimensions of the spacer elements 27 are larger than the maximum width of the locking openings 24. During construction of a 3D object, the space between the sheet elements 21 may be filled with a filling material, preferably before connecting the sheet elements 21 with each other.

Figure 7 shows another embodiment of sheet elements 40 to be used in a layered object manufacturing method according to the invention. The sheet elements 40 comprise a plate shaped base construction 41 , from which interlocking elements in the form of hook elements 42 and spacer elements 43 extend. The sheet elements 40 may be made out of a single plate, for example made of metal, whereby by laser cutting and folding the hook elements 42 and the spacer elements 43 are created. The openings that result from folding out the hook elements 42 and spacer elements 43 form locking openings 45 that are configured to receive the hook elements 42.

When the two sheet elements 40 are pressed on each other as indicated by arrows, the hook elements 42 will move through the locking openings 45 and couple with the edges of the locking openings 45 in an interlocking manner.

The spacer elements 43 ensure that the interlocked sheet elements 40 remain in a spaced relationship.

Figure 8 shows schematically an object manufacturing device 100 to construct 3D objects using sheet elements configured to interlock with each other. The object manufacturing device 100 comprises a sheet element supply 101 to hold at least one sheet element 102, a construction area 103, a positioning device 104, a control device 105, a separating device 106, a filling material deposit device 107, and a 3D printing head 108.

The sheet element supply 101 is configured to hold a number of sheet elements 102 that are used during construction of a 3D object in a 3D layered object manufacturing method. The sheet element 102 is preferably a large base sheet element from which multiple sheet elements of desired dimensions may be separated. The separating device 106 is configured to separate a sheet element 102a of desired dimensions from the sheet element 102. The separating device 106 may use any suitable separating technique such as cutting, sawing, laser cutting, etc. The separating device 106 is controlled by the control device 105 that provides information with respect to the desired dimensions of the next sheet element 102a to be separated.

The construction area 103 is the area in which the 3d object is created. The construction area 103 may comprise a construction table 109 on which the 3D object is supported during construction.

The positioning device 104 is configured to move a sheet element 102a of desired dimensions between the sheet element supply 101 and the construction area 103, and to position the sheet element 102a in a desired location within the construction area 103. During construction of a 3D object, the positioning device 104 is used to take a sheet element 102a out of the sheet element supply 101 and place it on top of a stack 1 10 of sheet elements already supported on the construction table 109. When the sheet element 102a is arranged in the desired location the positioning device 104 may also press the sheet element 102a on the stack 1 10 so that the first interlocking elements of the upper sheet element of the stack 1 10 interlock with the second interlocking elements of the sheet element 102a.

In the shown embodiment the positioning device 104 comprises a robot arm 1 1 1 and a holding device 1 12, for instance a clamping device or vacuum device, to hold the sheet element 102a. However, any other suitable positioning device may also be used. Also, a separate device may be provided to press the sheet element 102a on the stack 1 10 to obtain an interlocking connection between the sheet element 102a and the stack 1 10.

The filling material deposit device 107 is configured to cover at least one side of a sheet element at least partially with a layer of filling material 1 13. It may be desirable to provide a filling material between the sheet elements of the stack 1 10 of sheet elements. The filling material deposit device 107 may be used to cover the upper sheet element of the stack with a filling material before placing the next sheet element 110 on top of the stack 1 10.

The filling material may be any material. For medical implants, in particular bio-scaffolds, the filling material may be a liquid, gel or other viscous material containing cells or other biological material.

In an alternative embodiment, the filling material may, for certain applications, already be provided on the prefabricated sheet element 102.

Since the filling material does not have to contribute to the strength of the construction, the filling material may be relatively soft. The 3D printing head 108 may be used to print 3D printing material in combination with the stacked and interlocked sheet elements to form the object. In the shown embodiment, the 3D object that is constructed comprises an infill in the form of the stack 1 10 in which layers of filling material 1 13 are provided. Around the stack 1 10 a skin layer 1 14 is printed by the 3D printing head that covers the infill. In alternative embodiments the 3D printing material may also be provided at other locations.

The positioning device 104, the separating device 106, the filling material deposit device 107, and the 3D printing head 108 are controlled by the control device 105. This control device 105 instructs the different devices to carry out a layered object manufacturing method in which the followings steps can be taken.

On the basis of the desired object design, the control device 105 determines dimensions of sheet elements used to construct a stack of sheet elements 102a of desired shape and dimensions.

For each layer comprising a sheet element 102a, the control device 105 instructs the separating device 106 to separate a sheet element 102a with the desired dimensions. If the sheet element 102a is ready, the control device instructs the positioning device 104 to displace the sheet element 102a from the supply 101 to the construction area 103 and position is on top of a stack 1 10, if already present, and connect it thereto in an interlocking manner.

When desired, the filling material deposit device 107 may be instructed by the control device 105 to deposit a layer of filling material 1 13 on the sheet element 102a, and the 3D printing head 108 may be instructed by the control device 105 to deposit 3D printing material such as thermoplastics, photopolymers, ceramics or wax, at a desired location, i.e. in the shown embodiment to form a skin layer 1 14.

With this method 3D objects can be obstructed in a simple, quick and reliable manner, whereby the stack of interlocked sheet elements can provide a large strength to the 3D object. Furthermore, the method provides a large versatility in sizes, shapes and materials of objects to be constructed.

This makes the invention suitable for all kinds of objects. In particular, a stack of interlocked sheet elements can be used to construct relative large objects where the stack is used as infill to substantially increase production time.

In other objects, such as bio-scaffolds, the stack of interlocked sheet elements can be created without requiring any conventional processes such as thermo fusion of chemical binders that may be harmful for the cells that are incorporated in the object. Hereinabove, embodiments of sheet elements are shown and described comprising first interlocking elements arranged in a first pattern and second interlocking elements arranged in a second pattern. In these embodiments, the first pattern of the first interlocking elements and the second pattern of the second interlocking elements are designed to be coupled in a fixed. In other words, each of the first interlocking elements to be coupled with a second interlocking element is aligned with a specific one of the second interlocking elements.

In other embodiments, the first interlocking elements and the second interlocking elements may more randomly couple to each other. In such embodiment, the first interlocking elements and the second interlocking elements may be formed as hooks and loops, respectively, that are designed to lock into each other when the sheet elements on which the first interlocking elements and the second interlocking elements are provided, are placed on top of each other.

Claims

1. A method of layered object manufacturing, comprising the steps of:

2. The method of any of the preceding claims, wherein the method comprises covering the first side or the second side of the or more of the multiple sheet elements at least partially with a layer of filling material.

3. The method of the preceding claim, wherein the filling material comprises cells or other biological material.

4. The method of any of the preceding claims, wherein the step of providing multiple sheet elements each having a predetermined dimension, comprises:

determining the desired dimension for each sheet element, and

separating the respective sheet element with the desired dimension from a base sheet element having a larger dimension.

5. The method of any of the preceding claims, wherein the method comprises a step of 3D printing on or in the stacked multiple sheet elements, for example providing a skin layer around the stacked multiple sheet elements.

6. The method of any of the preceding claims, wherein the first interlocking elements of the first sheet element correspond to the first interlocking elements of the second sheet element and the third sheet element, and wherein the second interlocking elements of the first sheet element correspond to the second interlocking elements of the second sheet element and the third sheet element.

7. The method of any of the preceding claims, wherein the first interlocking means are provided in a first pattern and wherein the second interlocking means are provided in a second pattern, wherein the first pattern and the second pattern correspond.

8. The method of any of the preceding claims, wherein the sheet elements comprise spacer elements to hold the stacked and interlocked sheet elements in a spaced relationship with respect to each other.

9. The method of the preceding claim, wherein the spacer elements are formed by the first interlocking elements and/or second interlocking elements.

10. A stackable sheet element for use in layered object manufacturing, comprising

1 1 . The sheet element of the preceding claim, wherein the sheet element comprises a base construction extending in a first plane,

12. The sheet element of any of the preceding claims 10-1 1 , wherein the sheet element comprise spacer elements to hold stacked and interlocked sheet elements in a spaced relationship with respect to each other.

13. The sheet element of the preceding claim, wherein the spacer elements are at least partially formed by the first and/or second interlocking elements.

14. The sheet element of any of the preceding claims 1 1-13, wherein the second end of the locking projection or a part thereof is elastically movable in a direction substantially parallel to the first plane to allow the hook to pass a locking edge of a locking opening of a sheet element to be interlocked with the sheet element.

15. The sheet element of any of the preceding claims 10-14, wherein the first interlocking elements are arranged in a first pattern and the second interlocking elements are arranged in a second pattern, wherein the first pattern and the second pattern correspond.

16. An object manufacturing device, comprising:

a sheet element supply for holding one or more sheet elements configured to

mechanically interlock,

a construction area,

17. The object manufacturing device of the preceding claim, wherein the object

manufacturing device comprises a filling material deposit device configured to cover at least one side of a sheet element at least partially with a layer of filling material.

18. The object manufacturing device of any of the preceding claims 16-17, wherein the object manufacturing device comprises a separating device to separate a sheet element with a desired dimension from a base sheet element having a larger dimension.

19. The object manufacturing device of any of the preceding claims 16-18, wherein the object manufacturing device comprises a 3D printing head configured to print printing material in combination with the stacked and interlocked sheet elements to form the object.

20. An object manufactured using multiple sheet elements as claimed in any of the claims 10-15, wherein the multiple sheet elements are stacked in an interlocking manner to form a single body.

21 . The object of claim 20, wherein the object is a medical implant, such as a bio-scaffold.

22. The object of claim 20 or 21 , wherein between at least two sheet elements a layer of filling material is arranged, wherein the filling material preferably comprises cells or other biological material.

23. The object of any of the claims 20-22, wherein the object comprises a part of 3D printed material, for example a skin layer of 3D printed material at least partially enclosing the stack of interlocked sheet elements.