Patent Application
20190322052
The invention relates to a method for making tangible products by layerwise manufacturing. In particular, the present invention relates to such a method comprising the step of creating a layer of construction material with a uniform thickness alternately on a first building platform and a second building platform. Such a layer is created by depositing construction material and removing a surplus of such material to obtain the uniform thickness and the step of solidifying at least a part of the layer of construction material.
The invention also relates to a method comprising the steps of: (i) depositing in a deposition area, by using a material providing device, a layer of construction material onto a building platform for building a first layered product, (ii) conveying, by using a conveyor, the building platform away from the deposition area, (iii) removing the first layered product from the building platform, (iv) adjusting the distance between the material providing device and the building platform in a direction that is parallel to the building direction, and (v) depositing construction material onto said platform to obtain a second layered product after the first layered product has been removed.
The invention further relates to a production line for layerwise manufacturing of tangible products. In particular, the invention relates to such a production line comprising a first carrier comprising a first building platform for supporting a first tangible product and a second carrier comprising a second building platform for supporting a second tangible product. The production line further comprises a deposition head for depositing construction material onto the building platforms, a material remover for removing a surplus of the deposited construction material from the building platforms, and a solidification device for solidifying at least a part of the deposited construction material.
The invention also relates to a production line comprising: (i) a building platform for carrying a tangible product, (ii) a deposition head for providing a layer of construction material onto the building platform, (iii) a conveyor for conveying the building platform in a conveying plane, and (iv) height adjustment means for adjusting the distance between the deposition head and the building platform.
Layerwise manufacturing is a manufacturing method wherein tangible three-dimensional products are made by successive addition of layers on top of each other, which layers correspond to the cross sections at different levels of the tangible product. Layered products can be made by providing a uniform layer of liquid or powder, which liquid or powder is solidified in a predefined two-dimensional pattern corresponding to the cross section of the product to be manufactured. The remaining, not solidified material is removed afterwards. The layers can also be directly deposited in the required two-dimensional pattern, for example by printing. In such a method, the pattern is already determined during deposition of the material, not by the solidification. The material can be an ink or powder, which ink or powder is cured, sintered, or otherwise solidified to obtain a coherent product.
The products can be made on top of a building platform that can be displaced in a vertical direction. However, there are also layered manufacturing systems in which the product is hanging below the building platform. An example of such a system is disclosed in German patent application DE 10256672. Typically, such a system comprises a dish with liquid that can be solidified, for example by ultraviolet (UV) light. The building platform that is positioned above the bottom of the dish, moves upwards to allow the formation of a thin liquid film between platform (or previous solidified layer) and the bottom of the dish. The film is solidified in the predefined pattern and after this solidification the platform is move further upward. These steps are repeated until the product is finished. Finally, the finished product is removed from the platform and this platform can be used for making another product.
In a known method for layerwise manufacturing of a tangible three-dimensional product, a powder is used as a starting material, which powder is solidified by for example sintering. Such a method is disclosed in United States patent application US2009/0291308. According to this known method, a thin layer of powder is provided to an area that is delimited by a vertical wall and, at the bottom side, by a building platform. The layer is solidified by sintering into a coherent solid layer with a predefined shape, being a cross section of the product. Subsequently, the platform supporting the solidified layer moves downwards and a new powder layer is applied. The steps are repeated until the product is finished. Subsequently, the part of the powder that is not solidified and the finished product are removed before making another product.
The afore-mentioned system has one platform that is movable in the vertical direction. Such a system is in particular suitable for making products out of one type of material. It is possible to make several products having different shapes on such a platform, simultaneously. An example of such a method is disclosed in international patent application WO2004/014637. This known method is limited to products made out of one type of material. Also, powder-based systems may be suitable for making products in which individual layers are made out of different materials. Such a system is, for example, disclosed in United States patent application US2002/0145213. International patent application WO 2012/076205 discloses an apparatus that allows making different product quasi simultaneously. This apparatus comprises different building platforms, which provides more flexibility than systems with only one building platform.
European patent application EP 2289652 discloses an apparatus that allows making different products quasi simultaneously. This known apparatus comprises different building platforms, which provides more flexibility than systems with only one building platform. The powder that is used for creating one layer of the products on different building platforms is deposited by a deposition head in one batch on a surface next to the building platforms. After being deposited, the material is shifted onto the building platforms that are all positioned in such a way that the surplus of powder from one building platform is shifted towards a neighbouring platform until at the end of the series of platforms the surplus is deposited into a bin. The platforms, in particular the troughs comprising the platforms, are positioned directly against each other in order to avoid that powder falls off when surplus of construction material of a first platform is shifted towards a neighbouring, second platform. A disadvantage of this method and apparatus is that the powder that is needed for creating a layer on the different platforms has to be deposited once. In particular, when the number of platforms is high, or when the platforms are large, this requires that a huge amount of powder has to be shifted. Another disadvantage is that all the platforms receive the same powder.
Still another way of making tangible products by layerwise manufacturing is three-dimensional printing. In three-dimensional printing an ink is applied either as a continuous layer or in a predefined pattern corresponding to a cross section of the product. Three-dimensional printing is in certain aspects more flexible than the methods mentioned above, in particular when the ink is applied by printing heads. Different printing heads can be used to apply different materials for manufacturing composite products comprising several materials. Further, the printing heads can be switched on and off easily for better control of the manufacturing process. An example of a production line for layerwise manufacturing using print heads is disclosed in United States patent application US2009/0076643. This known production line can be used for making several tangible products by layerwise manufacturing. The production line comprises several printing heads for depositing material onto carriers, which printing heads are positioned above a conveyor that passes the carriers from one printing head to another printing head. The printing heads are positioned in line of each other in the conveying direction. Further, the height of each printing head can be adjusted with respect to the conveyor for example to compensate for increasing height of the product during the different stages of its manufacture, viz. the number of layers already deposited. This production line allows manufacturing of several products with different geometrical shape and different material composition. Each layer of the product is created by one or even more printing heads, resulting in a huge number of printing heads for manufacturing a product of substantial size. Also, international application WO2004/108398 discloses the use of one or more build stations for depositing material layerwise on a building platform. While the machine produces multiple products, it lacks potential for scaling up to industrial volumes.
It is an objective of the present invention to overcome the above mentioned and other problems of the prior art and to provide a method for rapid and flexible manufacturing of tangible products. This objection of the invention is obtained by a method for making tangible products by layerwise manufacturing comprising the steps of:
creating a layer of construction material with a uniform thickness alternately on a first building platform and a second building platform, wherein such a layer is created by depositing construction material and removing a surplus of such material to obtain the uniform thickness, and wherein the construction material is deposited on the first building platform and the second building platform individually, and
solidifying at least a part of the layer of construction material.
An advantage of depositing the construction material on the first building platform and the second building platform individually is that the amount of construction material that is deposited on each building platform can be better adapted to the amount of material needed for creating a layer with a uniform thickness on each platform. An effect is that it is not necessary to deposit on the first building platform both the material that is needed for creating the layer on this platform and the material that is needed for creating a layer on the second platform. Further, the surplus of material deposited on the first platform will be less than in a production line where the total amount of material needed for both platforms is first deposited on the first platform and thereafter partly shifted onto the second platform. Consequently, the production process will be faster. By individual deposition of material on the platforms, each of these platforms is provided with material directly from a deposition head, viz. a material providing device, so not via another platform. Where reference is made to depositing material onto a building platform, this includes depositing material on earlier deposited material or product such that the platform is supporting the deposited material.
In an embodiment of the method, the deposited layer of construction material is levelled by removing the surplus of the material. An advantage of combining the removal of the surplus of material and levelling the layer in one process step is that the layer of construction material with the proper uniform thickness is formed during the step of removing the surplus of material. An effect is that a layer of to be solidified material having the proper thickness is created in a fast way without additional steps and without additional equipment. Another effect is that the processes of removal and levelling can be better adapted to each other. These effects result in a faster and more flexible manufacturing of the products.
Several materials can be used for making tangible products by layerwise deposition. The deposited material may for example be a highly viscous material, for example a slurry. In an embodiment of the method, the construction material is a powder. An advantage of using a powder is that a powder can be deposited in a controlled way on a building platform. There are many methods and apparatus known by which a predefined amount of powder can be deposited and distributed on a platform. Another advantage of using a powder is that a powder may have a long shelf life, which allows storing of the material for a long period of time either in a warehouse or in the deposition equipment. It is further advantage of powders that the use of hazardous solvents may be avoided, which solvents otherwise should have to be exhausted.
In a further embodiment of the method, the removal of the surplus of material on a building platform starts while material is being deposited on the same building platform. An advantage of starting the removal even before all the construction material is deposited on a platform is that the amount of material on the building platform can be minimized. An effect is that only a minimum amount of material needs to be transported and that unwanted loss of material due to the movement of the building platform, including possible vibrations, and possible turbulence of surrounding air is minimized.
Another objective of the present invention is to provide a method for making tangible products by layerwise manufacturing, which method allows rapid manufacturing of such products at low costs. This objective of the invention, as shown in
(1) depositing in a deposition area, by using a material providing device, a layer of construction material onto a first building platform for building a first layered product,
(2) conveying, by using a conveyor, the first building platform away from the deposition area,
(3) removing the first layered product from the first building platform,
(4) adjusting the distance between the material providing device and the first building platform in a direction that is parallel to the building direction, wherein said adjusting is realized by moving the first building platform relative to the conveyor
(5) depositing construction material onto said first building platform to obtain a second layered product after the first layered product has been removed,
(6) using the conveyor to repeatedly move the first building platform past the material providing device to obtain the first layered product, and optionally
depositing in a deposition area, by using a material providing device, a layer of construction material onto a second building platform for building a third layered product before the first layered product has been removed.
An advantage of moving the building platform relative to the conveyor in order to adjust the distance between the material providing device and the building platform is that the material providing device need not to be moved and therefore can be placed at a fixed position. Keeping the material providing device at a fixed position has the effect that there is no need for stopping the deposition process during adjustment of the distance between the device and a platform onto which material is deposited. As a consequence, there is more time available for depositing material and therefore the device can be used more efficiently.
An advantage of moving the building platform repeatedly past the material providing device is that subsequent layers of the same material can be deposited with the same material providing device. Passing a material providing device repeatedly has the effect that the number of such devices for making tangible products can be limited compared to a method wherein each layer is deposited by a separate deposition device. The use of only one or a limited number of deposition devices makes the method more costs efficient than a method in which a building platform passes a deposition device only once.
An advantage of depositing construction material onto a second building platform while the first layered product is still being constructed is that multiple products are made quasi simultaneously. The effect of this quasi-simultaneous production is that more products can be made in a certain time span. Consequently, a more efficient production method is obtained.
Another objective of the present invention is to provide a production line for additive manufacturing of tangible products, which production line overcomes earlier mentioned and other problems of the prior art and which production line allows rapid and flexible manufacturing of products, including mutually different products.
This objective of the invention is obtained by a production line for layerwise manufacturing of tangible products comprising:
a first carrier comprising a first building platform for supporting a first tangible product,
a second carrier comprising a second building platform for supporting a second tangible product,
a deposition head for depositing construction material onto the building platforms,
a material remover for removing a surplus of the deposited construction material from the building platforms,
a solidification device for solidifying at least a part of the deposited construction material,
characterized by a platform conveyor for conveying the carriers towards and away from the deposition head repeatedly, which deposition head is suitable for depositing construction material on the first building platform and the second building platform individually.
An advantage of a production line comprising a deposition head which is suitable for depositing construction material on the first building platform and the second building platform individually is that the amount of material can be adapted to the amount needed for the uniform layer on the specific platform as was discussed before. An advantage of a conveyor for conveying the building platforms towards and away from the deposition head repeatedly is that subsequent layers can be deposited in an efficient way and that in principle only one deposition head is needed for making the products on the different platforms while still each product may be individually shaped. This results in an efficient and flexible production line. More in particular this allows making products having a different shape simultaneously.
In a preferred embodiment of the production line, each of the building platforms is enclosed in a trough for keeping construction material. An advantage of a through for keeping the construction material is that the material can be kept on the platforms without falling off, in particular during movement of the platforms. A further advantage is that the surface of the deposited material can be easily levelled to obtain a uniform thickness over the whole area of the building platform. The advantages of this embodiment allow fast moving of the building platforms and an efficient use of the whole area of the building platforms for manufacturing products.
Another embodiment of the production line comprises height adjustment means for moving the building platforms relative to the sidewalls of the trough in a direction parallel to the building direction. An advantage of moving a building platform relative to its sidewalls is that the height of the building platform can be adapted to the height of the product, viz. the height of the solidified part of the construction material. This allows that the distance between the surface of a most recent solidified layer and the rim of the sidewalls corresponds to the thickness of the next layer of material to be solidified. Such a geometry allows an easy removal of the surplus of deposited material and an easy levelling to obtain a layer with a uniform and predefined thickness.
In still another embodiment of the production line, the material remover comprises a rotatable roller for removing material from the building platform. An advantage of a roller for the removal of material is that the amount of material that accumulates in front of the material remover during use is reduced. For example, when a rigid wiper is used, material builds up as the wiper moves across the material. With a roller, at least a part of the surplus of material is removed away from the front of the roller to a more remote place. An effect is that the lateral forces on the deposited material, the already solidified material, and the building platform are minimized. Consequently, the removal of the material leads to no or only a minimal mechanical disturbance of the process.
The platform conveyor of the production line may be an endless conveyor. An advantage of an endless conveyor is that the platforms can move or can be moved along the deposition head and possible other processing equipment repeatedly without reversing the direction of the movement of the platforms. An effect is that the platforms may approach the deposition head and other equipment from the same direction for each subsequent layer that is deposited and solidified. This is in particular advantageous in case that certain process parameters such as the rotating direction of a roller need to be adapted to the direction of the movement of the building platform relative to such equipment.
In a further embodiment of the production line, the building platforms are movable along the platform conveyor individually. An advantage of building platforms that can move along the conveyor individually is that the velocity of the platforms of the production line need not to be the same at each moment in time for all the platforms. An effect is that the velocity of for example the first building platform can be adapted to a specific process without the need that also the velocity of the second building platform needs to be adapted to the velocity of the first platform. Consequently, the entire manufacturing process is more flexible and can be faster than in a production line where all platforms move with the same velocity.
Another objective of the present invention is to provide a production line for additive manufacturing of tangible products, which production line allows rapid manufacturing of mutually different products. This objective is obtained by a production line for layerwise manufacturing of tangible products as shown in
a first building platform (102) for carrying a tangible product,
a deposition head (101) for providing a layer of construction material onto the first building platform,
a conveyor (103) for conveying the first building platform in a conveying plane, wherein the conveyor conveys (105) the first building platform towards the deposition head and away from the deposition head repeatedly,
height adjustment means (107) for adjusting the distance between the deposition head and the first building platform, wherein the height adjustment means (107) is configured for displacing (104) the first building platform relative to the conveyor in a direction perpendicular to the conveying plane, and
a second building platform for receiving said construction material, which second building platform is conveyable by said conveyor and which second building platform is displaceable relative to the conveyor independent from the first building platform.
An advantage of a conveyor for repeatedly conveying the platform towards the deposition head and away from the deposition head is that each platform can pass a single deposition head several times. The effect of passing a single deposition head several times is that only a limited number of deposition heads, possibly only one deposition head is required for making a tangible product. A production line comprising only a limited number of deposition heads will cost less than a production line in which each layer is deposited by a separate deposition head.
An advantage of the height adjustment means being configured for displacing the building platform relative to the conveyor in a direction perpendicular to the conveying plane, is that the deposition head may be placed at a fixed position. After the building platform is removed from the deposition area (viz. away from the deposition head), the distance between the deposition head and the building platform can be adjusted. The effect is that the deposition head can be used to make another product during the time that the height of the building platform is being adjusted. This allows a more efficient use of the deposition head during the layerwise manufacturing of tangible products.
An advantage of a second building platform for receiving the material is that a second product, that may be different from the first product, can be made simultaneously with the first product. This makes the production line more efficient.
It will be appreciated that one or more elements of one embodiment may be combined with or replaced by an element of another embodiment.
The method for making tangible products by layerwise manufacturing will be described with reference to
In the first step of the method, an amount of construction material is deposited on a building platform. A construction material is a material that can be solidified in order to realize a tangible product. In general, the amount of material deposited will be more than the amount that is needed for creating a uniform layer having a predefined thickness. For example, to avoid a deficit somewhere in a layer of the product due to an uneven distribution of the deposited material or due to a defect in an earlier deposited layer. Preferably, the surplus of material is removed before solidification. Removing the surplus before solidification may be easier than removing solidified material. In addition, not removing the surplus before solidification may result in a varying and uneven quality of the different layers of a product, for example caused by a solidification that was not perfect.
After construction material has been deposited (4) on the first building platform for creating a layer for a first product, material is deposited (5) on the second building platform for making a second tangible product. For making a tangible product, usually multiple layers are required and the alternate deposition of just one layer on the first building platform and one layer on the second building platform will not satisfy. In practice, multiple layers will be deposited alternately on the first and the second platform. The deposition of the material on the second platform may take place simultaneous in time with the removal (6) of a surplus of material from the first building platform, or simultaneous in time with the solidification (8) of material on the first platform. This means that in
In a preferred embodiment of the method, the layer is levelled before solidification. If the construction material is deposited unevenly, for example because the material was deposited only at one position of a building platform, a certain degree of levelling may be obtained by vibrating the building platform. However, it is difficult to deposit the proper amount of material and, in addition, such a method would result in an accumulation of possible imperfections in the layers and consequently removing of surplus of material may be needed after solidification. Removing the surplus before solidification is advantageous for a proper solidification of the layer because the solidification device may be configured for solidifying a well defined amount of construction material. If the device is an energy source, then this source may be configured to provide an amount of energy that is tuned to the thickness of the layer to be solidified for an efficient solidification and adhesion to an earlier deposited layer. If the solidification device is a device for providing a binder, then the amount of binder may be adapted to the thickness of the layer that has to be solidified. Although it is possible to remove (6, 7) a well-defined amount of to be solidified material before levelling, it is preferred that the layer is levelled by removing the surplus of material. This means that the removal and the levelling take place in one and the same process as will be discussed in more detail below with reference to the production line.
The method can be applied for different type of materials, provided that a certain amount of material can be deposited on a platform and solidified as described before. The method and the production line are in particular suitable for making tangible products out of construction material that is provided in the form of a powder.
Certain steps in making the products can be performed simultaneously in order to realise a higher manufacturing speed. Construction material may for example be deposited (5) on the second platform or solidified (9) while at the same time a surplus of construction material is removed (6) from the first platform. Also, solidification (8) of a layer on the first platform make take place at the same time that a surplus of material is removed (7) from the second platform or at the same time that material is deposited (5) on the second platform. When a production line comprising more than two building platforms is applied, all three processes of depositing, removal, and solidification may take place at the same time on different platforms. Instead of performing just one processing step on a single platform, it is also possible to perform two or more steps on one platform simultaneously at least a part of the time. For example, it is possible to deposit construction material on a part of the area of a building platform, whereas at another part of the same building platform a surplus of earlier deposited material is removed. Analogously, it is for example possible to solidify a part of the levelled layer whereas at the same time another part of the deposited layer is levelled.
When the equipment used for depositing the construction material and the equipment used for removing the surplus of material are positioned close to each other in comparison to the size of a building platform, more in particular in the moving direction of the platform, the removal of the surplus of material may start while material is being deposited at another position on the same building platform.
The method for making tangible products by layerwise manufacturing can be extended with additional steps. Such steps may include mechanical tooling, for example milling or polishing, and coating of the products. An additional step may also comprise layerwise manufacturing of a part of product by using another type of deposition head. The first deposition head may for example deposit construction material as a powder form whereas a second deposition head deposits layers by means of inkjet. Also, a binder material may be deposited.
The method can advantageously be brought into practice by a production line that will be discussed here in more detail with reference to the embodiment shown schematically in
The production line may comprise multiple deposition heads for depositing different materials, for example different construction materials. A deposition head may comprise different nozzles for depositing different materials or for depositing the same material more evenly over a surface, more in particular a building platform. A deposition head may deposit the material at a single spot, for example in the middle of a building platform. However, it is preferred to distribute the material along the platform evenly during the deposition. For this purpose, the deposition head may comprise a slit corresponding to the width of the building platforms or multiple material outlets, for example nozzles or channels. The deposition head may also perform movements in a direction perpendicular to the building direction, for example in a direction perpendicular to the movement of the platforms. An even distribution of the material and also a more dense stacking of a powder may be supported by vibrations of the deposition head.
The trajectory of the carriers is determined by a conveyor (16) that allows the building platforms to be repeatedly moved toward and away from the deposition head. The carriers may be at a fixed position relative to the conveyor so that the velocity of the carriers is determined by the velocity of the conveyor. However, the carriers need not to be fixed to a conveyor, as will be discussed later. In
The production line further comprises a material remover (14) for removing a surplus of the construction material from a building platform. The surplus material may be removed by a scraper, a wiper, a blade, or by other mechanical means such as a roller. These mechanical means have in common that, in use, the building platform and the remover will move relative to each other in a direction that is perpendicular to the building direction. The building direction is the direction in which subsequent layers are stacked on top of each other. Preferably, the building platforms are conveyed by their carriers along the remover. This, however, does not exclude that the remover moves relative to, for example, the deposition head. The surplus of material may also be removed by suction or by a combination of mechanical means and suction.
In order to obtain a coherent product, the production line comprises a solidification device (15) for solidifying at least a part of the deposited construction material. The shape of the solidified part of a layer corresponds to a cross section of the product. Therefore, if the device is an energy source, the energy needs to be provided for most layers according to a predefined pattern. As discussed above for the method for making products, several types of energy sources may satisfy, including scanning lasers and lamps in combination with a mask for defining the pattern. When the solidification device is a device for providing a binder, the device may be adapted to deposit the binder in a pattern or the device may deposit binder material uniformly distributed over the layer of construction material. In the later case, additional equipment is needed to cure the binder in a pattern that corresponds to a cross section of the product. A binder may be used to manufacture an intermediate product comprising the construction material, which product is sufficiently coherent for careful handling but that may need to be sintered to obtain the desired mechanical properties. The production line may comprise an oven for such sintering.
To avoid the construction material falling off the building platform, the material can be confined within borders. In principle, it is possible to build walls with the construction material in order to keep construction material within borders and to assure that the surface area of layer that has to be solidified in a pattern is the same during the whole manufacturing process. This, however, requires that in addition to the product, walls also have to be manufactured. This does not only require additional construction material but may also require additional time. For these and other reasons, it is preferred that the carriers comprise a trough for keeping construction material. In case that the construction material is for example a powder, such a trough can keep the powder within fixed borders, viz. the side walls of the trough and possibly a bottom, to prevent powder from falling off the platform.
The trough may be at a fixed position relative to the building platform, viz. the building platform may be the bottom of the trough. After a certain amount of material is deposited onto the building platform, or into the trough, the surplus material has to be removed and the layer may be levelled. When the side walls of the trough extend above the top of the layer of which a part has to be solidified, it will be difficult to remove this surplus material. For these and other reasons, it is preferred that the production line comprises height adjustment means for moving the building platforms relative to the side walls of the trough in a direction parallel to the building direction. These height adjustment means may be incorporated in the conveyor, for example in case that the carriers are at a fixed position on the conveyor. The height adjustment means may however also be incorporated in the carriers. In both cases, the height of a platform may be adjusted, for example by an electromotor and a worm wheel or a stepping motor, a piezoelectric actuator, or pneumatically. In
The thickness (39) of the first layer after levelling may be defined by the distance between the building platform (35) and the rim (38) of the trough by using a remover, for example a scraper that is supported by the rim. By moving the scraper or a similar remover, all material that extends above the rim can be removed. During the manufacturing of the product, the platform is lowered (34) stepwise relative to the basis or the walls of the trough until the last layer is deposited. The thickness of each layer during this process is determined by the distance that the building platform is lowered for creating a layer. The lowering may be realised by using a stepping motor or actuator which may be computer controlled in order to obtain layers with a predefined thickness. Preferably, all layers have the same thickness, but the thickness need not to be the same. In case different materials are deposited, the thickness may be adapted to the type of material. The height of the building platform need not be the same in all the carriers and the height may be adjusted individually in order to make different products or to make identical products but which products are at a certain moment in time in a different stage of manufacturing.
The production line comprises a material remover for removing a surplus of the deposited construction material from the building platforms. In
Another embodiment of the remover is shown in
The remover may remove the surplus of material from the building platform into a bin. The material that is deposited into a bin may be removed periodically, for example for re-use in the deposition head. The position of a bin depends on the type of material remover and its orientation relative to the building platform. The bin may have a fixed position relative to the remover or the bin may have a fixed position relative to a carrier. In the later case, the bin may be attached to the carrier. Such a construction requires a large number of bins in a production line comprising many building platforms. An advantage may be that only the material that is deposited on the corresponding platform is deposited in a bin. In particular, when different products are made out of different materials, such construction is advantageous in view of possible re-use or recycling of the material. A bin may be positioned besides the platform conveyor as shown in
The platform conveyor of the production line preferably is an endless conveyor. In addition to this endless conveyor, the production line may comprise a conveyor for supplying building platforms to the endless conveyor and a conveyor for removing building platforms from the endless conveyor. Alternatively, the production line may comprise pick and place equipment for placing platforms on the endless platform conveyor and picking platforms from the conveyor. In a preferred embodiment, troughs comprising the platform are placed on the conveyor and removed from the conveyor. Instead of placing and removing only the troughs and their contents, complete carriers may be placed and removed. The building platforms entering the endless conveyor may be empty whereas the building platforms leaving the endless conveyor may comprise the product, including not solidified material surrounding the product made from solidified material. An embodiment of the production line comprising an endless platform conveyor is shown in
The production line further comprises nine building platforms (702 to 709) having dimensions that allow the platforms to be at a relative large distance to each other on the conveyor. Such a production line with a relative small number of platforms compared to the length of the conveyor may be preferred in a production line where the carriers comprising the building platforms can move relative to the conveyor and relative to each other. The relative large distance between the carriers allows that the velocity of the different platforms may be different during a certain period of time. Platforms where the layer of construction material is solidified may for example move faster than platforms comprising a layer that is not solidified yet. During a short period of time, the direction of the movement of some carriers relative to each other may be different. In a production line where the building platforms are at a fixed position relative to the conveyor, the distance between the platforms may be small. An advantage of such a production line is that it possible to have more building platforms, and thus more products on a conveyor of the same length as the conveyor in a production line where the carriers can move individually with different velocity. In the embodiment of the production line shown in
The movement direction (61) of the carriers will in general be such that during one cycle, a carrier and the corresponding building platform first pass the deposition head (13), then the material remover (14) and finally the solidification device (15). However, the movement of the carriers may be in an opposite direction, although this may be less efficient because it may require an extra cycle for a layer to be solidified in a pattern. While moving in this opposite direction, the not yet solidified layer may pass the solidification device a first time without being solidified before a surplus of material is removed. In case the material remover is a device for removing solidified material, for example by using a knife, such opposite direction may be preferred.
Another preferred embodiment of the method for making several tangible products according to the invention will be discussed with reference to the flow diagram of
Because using a printing head is a preferred embodiment for providing the construction material, in the following the word “deposition head” is used frequently. It is appreciated, however, that the use of this word is not intended to limit the invention to any specific material providing device or technology. A deposition head is any kind of device that is suitable for depositing a material on the building platform, on a previously deposited layer carried by the platform, or on a substrate or other object or product carried by the building platform. Thus, it includes also atomic layer deposition, a technique that can be used to apply thin layers of specific materials.
Where in the following reference is made to the deposition of a material onto a building platform or of placing an object on the platform, this includes the deposition and placing on the platform itself, on a substrate or object or product carried by the platform, and on previously deposited layers.
When reference is made to a product made by layerwise manufacturing on a building platform, it is appreciated that this includes the situation in which the building platform carries several products. The several products on a single building platform may have the same geometry or different geometries. Because such separate products are located on the same building platform, they will have a certain resemblance, more in particular a similar layered structure.
After the first layer of the construction material is deposited on the building platform, the deposited layer is transported away (2A) from the deposition head by the conveyor that conveys the platform on which the layer is deposited.
For accurate manufacturing, the distance between the deposition head and the target area, which is the area on which the material is deposited, may need to be the same for all layers during the deposition of the material. For the first layer this will be the building platform or a substrate. For subsequent layers, the target area is defined by the preceding layer, which preceding layer may comprise a solidified layer and supporting parts as will be discussed later. The target area may also be an object that is inserted to be encapsulated, which object may be produced by layerwise manufacturing or otherwise. In order to keep the distance between the deposition head and the target area constant, the platform can be displaced (4A) relative to the conveyor in a direction that is parallel to the building direction. Usually, this will be the vertical direction.
After having adjusted the height of the platform, a new layer can be deposited on top of the previously deposited layer. The process of depositing a layer, moving it away from the deposition head, displacing the platform relative to the conveyor in a downward direction, and providing the layer to the same deposition head again, is repeated (6A) until the product is finished. The method can favourably be applied by moving the conveyor fast, in particular with a speed of 1 m/s or faster, for example 2 m/s. Typically the platform may pass a material providing device at least every 10 seconds, for example every 5 seconds or even every 1 second. During moving the layer, the layer can for example be cured or machined or another deposition head may deposit another or the same material.
Although it may be preferred to adjust the distance between the deposition head and the target area after deposition of each layer, it may be sufficient to adjust the height of the platform not after the deposition of each layer, but only when a few layers have been deposited, for example five layers. However, in case that the height is not adjusted after depositing each layer, the timing of the deposition head may need adjustment because of the following. The material needs some time to reach the deposition area after being ejected by the deposition head. During this time, the building platform will move and consequently the position where the droplet of the material will reach the deposition area will change when the distance between deposition head and the deposition area changes.
As mentioned above, the displacement of the platform, after depositing a layer or before depositing an additional layer, will usually be downwards. If, however, for example another type of material has to be deposited on top of the previously deposited layer, then the distance between the depositing head and the building platform may need to be smaller. In such a case, the platform is displaced upwards. In other situations, the platform may not need to be displaced at all, for example because the subsequent layer is to be deposited in the same building plane at positions where there is no material of the previously deposited layer. Apart from the case where holes in a previous layer have to be filled, a subsequent layer may also be deposited into the previous layer, so injecting the previous layer with another material.
After the product is finished, it is removed (3A) from the building platform. This removal may, for example, be realized by picking up the product from the platform or by transferring the substrate on which the product is built, from the platform. After the product is removed, the platform is available for the manufacturing of a second product. The height of the empty building platform is adjusted (4A) as to provide the proper distance between the building platform and the deposition head for depositing the first layer of the second product. The platform is moved (2A) towards the deposition head for receiving the first layer of the second product (5A), either before adjusting its height, after adjusting, or during adjusting. This second product is produced in a similar way as the first product, so that in fact the production process (20A) is repeated. This second product need not be the same as previous product, although it may be the same, because the shape and composition of the layers can be determined for each individual layer. Although the word second is used here, the word should not be interpreted in its literal sense. Actually, the second product may be any subsequent product.
Another embodiment of the method is discussed with reference to
In case that the deposited layer is a continuous layer of construction material, this layer has to be solidified in the required shape by solidification means that are provided locally. In case that the construction material has to be solidified with electromagnetic radiation, for example UV light, this radiation can be provided locally in several ways. For example a mask, preferably a programmable mask, can be used to subject a predefined part of the layer to the radiation. Instead of a mask a matrix with individually addressable light sources, for example light emitting diodes, can be used. Another way of providing light in the required pattern is a scanning laser or moving mirrors for directing the light in the proper direction.
Preferably, the method is performed with equipment comprising several platforms because then the advantages of this method are exploited optimally. In case that several platforms are used for implementing the method, the steps may be similar to those described above, replacing the word platform by the nth platform, where n is the sequential number of the platform. However, the method according to the invention does not require that all the platforms are used for the manufacturing of a layered product. For example, some of the platforms may be kept empty. Neither is it required that the removal of the products is performed in the sequence of the arrangement of the platforms. Actually, the method can be applied while operating each of the platforms independently of all others.
Another embodiment of the method, shown in
According to the method steps shown in
The supporting material can be deposited either after a layer of construction material has been deposited in the predefined shape or before. Because the spaces filled with the construction material and the supporting material are complementary, they may form a continuous layer of which a part will be solidified, viz. the part being the construction material. The layer as whole, viz. the solidified part and the part composed of supporting material, is the basis on which a subsequent layer can be deposited.
A supporting structure can also be obtained from the construction material or from a—different—construction material that is solidified. Such a supporting structure may for example have a honeycomb geometry or other type of structure that can easily be broken apart later.
In a further embodiment of the method is shown in
In particular, such outside processing is advantageous if such processing is not compatible with the speed of layerwise manufacturing, viz. the speed of the conveyor. It is in particular advantageous if the processing is a batch process that requires special equipment, like for example electroless plating, spark erosion or laser drilling.
In the embodiment of the method comprising the step of further processing the product, the product may be placed back on another building platform than the one from which it was removed. This may for example be the case when the second product is still on the building platform. In an embodiment of the method comprising further processing of the product, the processed product is placed on the same platform as from which it was removed. According to this embodiment, the second product is removed from the building platform before the processed first product is replaced. When a complex product has to be manufactured comprising both the first and the second product, the first product may be placed on the same building platform, so either on top of the second product or aside. For this purpose, the method may comprise a step of providing a machine readable code, for example a barcode or QR code, to the platform, the substrate or the product. Such a method further may comprise a step of reading the code and determining what the next processing step is for the product.
Layerwise manufacturing is an additive process in which material is added to earlier deposited material. However, products made by such a process may need to be tooled, for example by milling, drilling, or smoothening by polishing. The process of layerwise manufacturing may result in an accumulation of errors, for example in the thickness, viz. height, of the product. For these and other reasons sometimes material has to be removed from the already deposited layers or product. Such a removal may take place outside the deposition equipment, viz. away from the conveyor, as described above. However, when adjustment of the thickness is required due to imperfections, the removal of the material may be performed while the product is on the building platform. Therefore, the method may comprise a step of removing material from the product while said product is located on the platform.
Products made by layerwise manufacturing may be combined with other objects to obtain a compound product. Such other objects may be electrical, optical, magnetic or mechanical functional devices. Examples of such functional devices are computer chips, light emitting diodes, lens systems, actuators, piezoelectric elements, loudspeakers, microphones, and batteries. Such a functional object may be joined with the product after the layerwise manufacturing is completed. However, when the object has to be encapsulated or otherwise integrated with the product, the object has to be placed during the layerwise manufacturing. In an embodiment of the invention, the method comprises the step of joining an object with the layerwise manufactured product by placing the object on the building platform. The object may be placed directly on the platform before starting the layerwise deposition. The object may also be placed after one or more layers have been deposited. The object may even be placed after all layers have been deposited.
Another embodiment of the invention is a production line for layerwise manufacturing of tangible products. Such a production line will be discussed here with reference to the embodiment of the production line shown in
Around this conveyor, equipment such as a material deposition head (101) is positioned for the layerwise manufacturing of products. The inventors have found that an endless conveyor is very well suited for layerwise manufacturing because a position on such a conveyor passes a fixed external point several times. This allows processes, like deposition of a layer, to be performed repeatedly without requiring special measures. For products that are made out of one material, just one deposition head may be sufficient to make the product when an endless conveyor is used. In systems like the one disclosed in US patent application US2009/0076643, many printing heads, or even a huge number of printing heads are needed, namely at least one printing head per layer.
The conveyor may for example be a rotatable disc as shown in
As shown in
To allow manufacturing products with detailed structures, the lateral resolution of the deposition process should be high. Among others, this lateral resolution is determined by the type of deposition head. In embodiments where a continuous layer is deposited which is solidified by for example electromagnetic radiation, more in particular UV light, the resolution may be lower than 10 micrometre or even lower than 1 micrometre. When the two-dimensional structure is determined by a printing process, the resolution may be lower than 100 micrometre, or more in particular lower than 10 micrometre. It is appreciated that not all the deposition heads of the production line need to have the same resolution. The type of deposition head, the material to be deposited and the functionality of the deposited layer in the product to be fabricated will, among other parameters, determine what resolution is required and feasible.
The production line comprises one or more building platforms (102) for carrying layers of material during the manufacturing of a product as shown in the
Returning to the embodiment shown in
The distance between the deposition head and the target area can also be adjusted by displacing the deposition head. However, such a construction has the disadvantage that the deposition head has to move to its new position in a very short time, namely the time that it takes to move the platforms over a distance that is equal to the spacing of two platform in the conveying direction. For a typical conveying speed of 2 m/s and a spacing between two platforms of a centimetre, the time interval is only 5 ms. The time that is available for displacing the platform is much larger. For a conveyor in which the trajectory of the platforms is for example 6 metres, the available time is about 3 seconds, which is a factor of 600 longer.
The height adjustment means and the building platform may be directly placed or on or attached to the conveyor as is shown schematically in
The height of the building platforms may also be adjusted at one or more fixed positions along the endless conveyor by a tuneable height adjustment device. A preferred embodiment of such a height adjustment device is shown schematically in
Although all the carriers may be similar in construction, it is preferred that the position of the wheel (341) is not the same for all the carriers as will be explained here. The ramp is in particular suited for making large movements. Due to a large conveying speed of the carriers and the small distance between the carriers, it will be very difficult to move two neighbouring carriers to different heights because this would require huge accelerations. To solve this problem, the apparatus may comprise multiple ramps in parallel as shown in
The production line as shown in
The production line may comprise a curing device (110) for curing a layer of construction material to obtain a patterned solidified and coherent layer corresponding to a cross section of the product to be manufactured. Such a curing device may be a device providing electromagnetic radiation, for example ultraviolet light. Preferably, such a UV source can provide the UV radiation in a predefined patter, for example by means of a scanning laser or an array of small UV sources or light emitting diodes. However, in some embodiments of the production line, the curing device may provide a more or less homogeneous curing condition along the whole area of the layer. Such a homogeneous source, for example a UV lamp, can be applied for after curing of a pre-cured layer. It may also be applied if the layer is composed of two types of materials; the curable construction material and a supporting material that is not cured under these conditions.
Preferably, the production line comprises two or more building platforms. Such several building platform allow that the advantages of the production line can be exploited even better. During use of a production line comprising several building platforms, there may be products in different stage of construction on the conveyor resulting in very flexible production. Several platforms may also be advantageously when for example the step of picking the product from the building requires relatively much time, more in particular requires that the conveyor is slowed down. In such a case, one may prefer to make products on the different platforms and after the last product is finished, slow down the conveyor to pick the products form the building platforms.
To obtain a flexible production line that allows producing different products and to produce products at different stages of production simultaneously, the different platforms may be displaceable independent of each other in the building direction relative to the conveyor.
During additive manufacturing, layers are deposited on top of each other. This may result in an accumulation of errors in the thickness. Also, picking of a semi-finished product and replacing it on a platform may introduce errors. For this and other reasons, it may be advantageous to have the possibility to adjust the height of a product. If the height during a certain stage of the fabrication is too low, an additional layer can be deposited. If, however, the product is too high, some material has to be removed. To allow such a removal, the production line may comprise a cutting unit for removing material from the already manufactured product. Such a cutting unit may comprise a knife that is adjusted such as to remove a slice of the solidified material. Due to the fact that the apparatus allows fast movement of the platforms and thus of the products relative to the knife, typically the speed can be up to several metres per second, such a cutting may be favourable applied. An embodiment of such a cutting unit is shown in
The invention is not limited to specific dimensions or technical specifications of the production line and its elements. The building platforms may have a rectangular area which is typically less than 400 mm×200 mm, more particular less than 200 mm×200 mm, or less than 100×200 mm, or even more particular less than 100 mm×50 mm. The inventors preferred a building area of 50 mm×75 mm. However, the deposition area may also be larger than 400 mm×200 mm. The building platform need not to be rectangular, but may for example also be elliptical, or more specific round as shown in
An embodiment of a production line (200) for layerwise manufacturing of tangible products is shown in
The production line may further comprise a second conveyor (215) for processing a product in a processing station (216). Such a processing station may, for example, be configured for a treating a surface of the product, for depositing an atomic layer, or for inserting electronic components. Products can be placed on the second conveyor by a robot (204) or can be picked from the second conveyor to be placed on a platform (205). However, the first and second conveyors may also be configured so as that a platform is directed from the first conveyor to the second conveyor. The apparatus further may comprise a reader (217) for automatic reading of codes attached to the platforms, substrates or products. The reader may be an optical reader suitable for reading codes like a barcode or a QR code. The reader may, however, also be a radio reader suitable for reading information from for example RFID tags, or a magnetic reader for reading information in a magnetisable strip. The reader may send the information to a control unit, which control unit may comprise a software program for storing information about the platform and the product placed on it. Such software program may determine the further processing steps that have to be performed with respect to the product or the platform.
The invention relates to a method and an apparatus for making tangible products. The constructional parts mentioned in relation to the method therefore may be implemented in the apparatus, even if this is not mentioned explicitly. Further, a person skilled in the art will know how to implement the method steps into the apparatus. Also, processing steps referred to in the description of the apparatus may be implemented in the method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12190707.5 | Oct 2012 | EP | regional |
| 14166552.1 | Apr 2014 | EP | regional |
This application claims priority from and is a continuation of U.S. patent application Ser. No. 15,307,683, filed Oct. 28, 2016, which claims priority from International Patent Application Number PCT/NL2015/050292, filed Apr. 30, 2015, which claims priority from EP 14166552.1, filed Apr. 30, 2014, each of which is incorporated herein by reference. This application also claims priority from and is a continuation-in-part of U.S. patent application Ser. No. 16/274,810, filed Feb. 13, 2019, which is a continuation of U.S. patent application Ser. No. 14/439,690, filed Apr. 30, 2015, now U.S. Pat. No. 10,226,894, issued Mar. 12, 2019, which claims priority from International Patent Application Number PCT/NL2013/050774, filed Oct. 30, 2013, which claims priority from EP 12190707.5, filed Oct. 31, 2012, all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15307683 | Oct 2016 | US |
| Child | 16371881 | US | |
| Parent | 14439690 | Apr 2015 | US |
| Child | 15307683 | US |
