Method and apparatus for producing three-dimensional workpiece by additive layer molding method

Abstract

To provide a method for producing a three-dimensional workpiece by an additive layer molding method.SOLUTION: A method includes: defining an irradiation section, in particular an irradiation stripe, on a material layer to be irradiated, in an additive layer molding method, with an irradiation beam scanned across the material layer; and defining, within the irradiation section, two or more parallel or substantially parallel scanning vectors for the scanning of an irradiation beam across the material layer, wherein: all scanning vectors within the irradiation section are parallel or substantially parallel with respect to each other; and based on the defining of the two or more parallel or substantially parallel scanning vectors, a line can be obtained which connects a first location, on the material layer, of a change in irradiation energy density of the irradiation beam for a first vector of the two or more parallel or substantially parallel scanning vectors and a second location, on the material layer, of a change in irradiation energy density of the irradiation beam for a second vector of the two or more parallel or substantially parallel scanning vectors.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention generally relates to a method for defining two or more scan vectors used to irradiate a material layer in an additive layer manufacturing process, a computer program product including program portions that perform the method when the computer program product is executed on one or more computing devices, an apparatus for manufacturing a three-dimensional workpiece by an additive layer manufacturing process, and a method including providing data for implementing the above method using the apparatus for manufacturing a three-dimensional workpiece by an additive layer manufacturing process. [Background technology]

[0002] In additive manufacturing, a workpiece is produced layer-by-layer by creating a series of solidified, interconnected layers of the workpiece. Such processes can be distinguished by the type of feedstock material and / or the manner in which said feedstock material is solidified to produce the workpiece.

[0003] For example, powder bed fusion is a type of additive layering method by which powdered, especially metal and / or ceramic, raw materials can be processed into three-dimensional workpieces of complex shape. For this purpose, a layer of raw material powder is applied to a carrier and subjected to site-selective laser radiation, for example according to the desired shape of the workpiece to be produced. The laser radiation penetrating the powder layer causes heating of the raw material powder particles and thus their melting or sintering. Further raw material powder layers are applied to the layer already subjected to laser treatment on the carrier and processed until the workpiece has the desired shape and size. Selective laser melting or laser sintering can be used in particular for the production of prototypes, tools, replacement parts or medical prostheses based on CAD data, for example dentures, orthopedic prostheses.

[0004] Fused deposition modeling, or material jetting, on the other hand, represents another type of additive deposition process in which unsolidified feedstock material is fed to a printing head which deposits the material onto a carrier, where it solidifies.

[0005] An important parameter of additive manufacturing is the quality of the workpieces produced, which can be influenced by various parameters, and known solutions do not always achieve the desired quality.

[0006] Currently, stripe widths (widths of scan vectors for scanning the radiation beam across the material layer) are defined in the stripe scanning method. Within these stripes, there are scan vectors of equal or varying length depending on the workpiece shape. The start and end points of the scan vectors are next to each other, substantially independent of the workpiece shape, forming lines between the stripes (FIG. 1). In most cases, the stripes in the interior of the workpiece have vectors of substantially equal length, while the stripes in the contour area of ​​the workpiece have vectors of varying length depending on the workpiece shape.

[0007] The overlap or distance between two stripes can be adjusted by the stripe offset: a positive value of the stripe offset results in distance between the two stripes, a negative value of the stripe offset results in an overlap.

[0008] The inventors have found that if this value is not optimally set or the melt pool size increases during the additive manufacturing process due to environmental influences (e.g., gas flow changes, pressure fluctuations), defects or pores may occur if the overlap or distance between the two stripes is too large (points in FIG. 1). Since the start and end points of the scanning vector are in line, several linearly arranged chain-like defects or pores may occur (linear points in the enclosed area in FIG. 1).

[0009] The inventors have realized that statistically arranged porosity or defects do degrade the quality of the workpiece to a certain extent, but linear arrays of defects or porosity should be avoided, because, unlike statistically distributed porosity, when such linear arrays of defects or porosity exist once or many times in the workpiece, chain-like defects or porosity will form linear defects, cracks and a kind of pre-determined failure point under load, which may lead to premature mechanical failure of the workpiece. Summary of the Invention [Problem to be solved by the invention]

[0010] It is therefore an object of the present invention to improve the quality of three-dimensional workpieces, in particular those manufactured using additive layered manufacturing methods. [Means for solving the problem]

[0011] The invention is defined in the independent claims. Preferred embodiments of the invention are outlined in the dependent claims.

[0012] The method of the invention described comprises defining an irradiation section, in particular an irradiation stripe, on a material layer that is irradiated with a radiation beam scanned across the material layer in an additive layer manufacturing process, and defining two or more parallel or substantially parallel scanning vectors within the irradiation section for said scanning for said radiation beam across the material layer, where all scanning vectors within the irradiation section are parallel or substantially parallel to one another, and based on said definition of the two or more parallel or substantially parallel scanning vectors, a line is defined that connects a first location of a change in the radiation energy density on the material layer of the radiation beam for a first vector of the two or more parallel or substantially parallel scanning vectors and a second location of a change in the radiation energy density on the material layer of the radiation beam for a second vector of the two or more parallel or substantially parallel scanning vectors. a first scanning vector and a second scanning vector are adjacent scanning vectors, the distance between the first location and the second location is smaller than (i) the distance between the first location and a third location of the change in irradiation energy density of the irradiation beam for a second vector of the two or more parallel or substantially parallel scanning vectors, and / or (ii) the distance between the second location and a fourth location of the change in irradiation energy density of the irradiation beam for a first vector of the two or more parallel or substantially parallel scanning vectors, and an angle different from 90 degrees is formed (i) between the first scanning vector and the line and / or (ii) between the second scanning vector and the line, regardless of (a) the shape of a workpiece manufactured using the additive manufacturing method and (b) the orientation of the two or more parallel or substantially parallel scanning vectors relative to the orientation of the irradiation section.

[0013] An angle different from 90 degrees, regardless of the shape of the workpiece manufactured using additive manufacturing, means that the angle is different from 90 degrees, regardless of where, for example, two or more parallel or substantially parallel scan vectors are arranged in the material layer when manufacturing the workpiece. In particular, an angle different from 90 degrees, regardless of the shape of the workpiece manufactured using additive manufacturing, means that the angle is different from 90 degrees, regardless of whether, for example, two or more parallel or substantially parallel scan vectors are defined on the contour or contour area of ​​the workpiece (i.e., regardless of whether an illumination section in which two or more parallel or substantially parallel scan vectors are defined is defined on the contour or contour area of ​​the workpiece). It should be understood that in the contour or contour area, the scan vector may be defined to a length shorter than the scan vector defined in the non-contour area.

[0014] An angle different from 90 degrees, regardless of the orientation of two or more parallel or substantially parallel scanning vectors relative to the orientation of the illumination section, means that the angle is different from 90 degrees, for example, regardless of whether the scanning vectors are defined to be parallel or substantially parallel to one or more of the edges of the illumination section, or whether the scanning vectors are not parallel or substantially parallel to one or more of the edges of the illumination section. In some embodiments, the illumination section is defined as a square or rectangular illumination section, such that the scanning vectors in the illumination section can be parallel (or substantially parallel) to the edges of the square or rectangular illumination section, or the scanning vectors are at an angle (i.e. not parallel) to the edges of the illumination section. However, according to the implementations described herein, the angle is different from 90 degrees, regardless of whether the scanning vectors (with a square or rectangular illumination section) in this example are parallel to the edges of the illumination section.

[0015] In some embodiments, the orientation of the illumination section is defined based on the edges of the illumination section, for example when the illumination section is square or rectangular, in other embodiments, the illumination section can be oval such that the orientation of the illumination section can be defined by the long and short axes of the oval illumination section.

[0016] Using this method, linear array porosity or defects can be avoided (at least to a certain extent), thereby improving the quality of workpieces manufactured using additive manufacturing methods, since a change in the irradiation energy density of the irradiation beam (in some instances, from zero to a value greater than zero or vice versa, or alternatively or in addition to, from a first non-zero value to a second non-zero value that is less than or greater than the first value) can ultimately result in porosity or defects in the solidified material.

[0017] A change in the irradiated energy density can be obtained, for example, by changing the power of the energy source, changing the beam diameter at the working surface (i.e., the size of the beam spot on the working surface), changing the moving speed or trajectory of the beam spot, the distance between adjacent vectors (i.e., adjacent moving traces), the overlap of adjacent irradiation traces resulting from the distance between adjacent vectors and the size of the beam spot, and the number of scanning vectors in the irradiation section. To change the irradiated energy density, one, more or all of the above parameters can be changed.

[0018] In some embodiments, only a portion of all scan vectors are defined within an illumination section such that the angle formed between said scan vector and a line is different from 90 degrees. In some other embodiments, all (adjacent) scan vectors within an illumination section are defined such that the angle formed between said scan vector and a line is different from 90 degrees.

[0019] Implementations of the methods described herein thus allow the locations of variations in irradiation energy density to be varied between adjacent parallel or substantially parallel scan vectors, thus avoiding linear chain porosity or defects, thereby improving the quality of three-dimensional workpieces produced using additive manufacturing methods.

[0020] In some embodiments of the above method, the angle different from 90 degrees is formed based on adjacent scan vectors of each pair of two or more scan vectors, thereby avoiding linear chains of pores or defects throughout the illuminated section.

[0021] In some embodiments of the method, the angle is at least 5 degrees, preferably at least 10 degrees, more preferably at least 15 degrees, different from 90 degrees. The variation of the first and second locations of the respective changes in the irradiated energy density for the first and second vectors, respectively, of the two or more scanning vectors can be increased so that said locations are provided on the material layer such that the arrangement differs as much as possible from a linear arrangement. Thus, linear chain-like pores or defects are avoided as much as possible, thereby improving the quality of three-dimensional workpieces manufactured using additive manufacturing methods.

[0022] In some embodiments of the method, the variation in irradiation energy density includes the start and / or end of the scanning vector at each of the locations. The method can be particularly advantageous since porosity and defects occur especially when the irradiation beam first strikes the material layer and / or when the irradiation beam no longer strikes the material layer at a particular location (i.e., when the irradiation beam is no longer scanned across the material layer). Possible serious porosity and / or defects can thus be avoided from occurring on the solidified material in a linear array.

[0023] In some embodiments of the method, the angle formed different from 90 degrees is based on a) defining the first and second of two or more parallel or substantially parallel scanning vectors to have (i) respectively different lengths and / or (ii) respectively different starting points and / or (iii) respectively different end points, and / or (b) the start point of one of the first and second of the scanning vectors being different from the end point of the other of the first and second of the scanning vectors. The different start points of the first and second of the two or more scanning vectors can mean that a connecting line between the respective start points is not orthogonal to the first of the two or more scanning vectors and / or is not orthogonal to the second of the two or more scanning vectors. Similarly, the different end points of the first and second of the two or more scanning vectors can mean that a connecting line between the respective end points is not orthogonal to the first of the two or more scanning vectors and / or is not orthogonal to the second of the two or more scanning vectors. Similarly, a start point of one of the first and second of the two or more scan vectors being different from an end point of the other of the first and second of the two or more scan vectors can mean that a connecting line between the start point and the end point is not orthogonal to the first of the two or more scan vectors and / or is not orthogonal to the second of the two or more scan vectors. By using such an implementation of the method, chain porosity and / or defects can be avoided, thereby improving the quality of three-dimensional workpieces manufactured using additive manufacturing methods.

[0024] In some embodiments, the method further comprises defining an area within the illumination section, the first location and the second location being located within the area along respective straight lines along which a respective first vector of the two or more scanning vectors and a respective second vector of the two or more scanning vectors are defined. Chain porosity and / or defects can be avoided by defining the start and end points of the scanning vectors (or roughly the respective locations of changes in the illumination energy density) within this area within the illumination section such that a condition is satisfied that an angle between the first scanning vector and the line and / or between the second scanning vector and the line is different from 90 degrees.

[0025] In some embodiments of the method, the first locations and the second locations are randomly arranged within the area. By randomly arranging the first locations and the second locations within the area, chain pores and / or defects may be avoided in terms of stochastic arrangement.

[0026] In some embodiments of the method, the first locations and the second locations are evenly distributed within the area, thereby advantageously avoiding chain porosity and / or defects within the area, the even distribution including an average distance between the locations (e.g., between the locations of change in irradiation energy density of all scan vectors within the area) exceeding a threshold distance.

[0027] In some embodiments of the method, the connecting line of the locations of every other scan vector forms a straight line. For one or more of the scan vectors, the starting point can be located on a straight line, and for the other one or more of the scan vectors, the end point can be located on a straight line. In some embodiments, two straight lines are formed, the first straight line being based on a first set of scan vectors (e.g., the first scan vector, the third scan vector, the fifth scan vector, etc.) and the second straight line being based on a second set of scan vectors (e.g., the second scan vector, the fourth scan vector, the sixth scan vector, etc.). This allows distributing the locations of each change in the irradiating energy density of the irradiating beam, avoiding interconnected linear chains of pores and / or defects in the area.

[0028] In some embodiments of the method, said locations are located on the material layer according to a wave-like curve, in particular a sinusoidal curve, linear chain pores and / or defects can thus be avoided in the solidified material layer.

[0029] In some embodiments of the invention, the locations are arranged on the material layer according to a zigzag pattern. Linear chain porosity and / or defects can thus be avoided in the at least partially solidified material layer by offsetting the locations every xth scan vector by a set magnitude.

[0030] In some embodiments of the method, the distance between the first location and the second location exceeds a preset threshold, and linear chain pores and / or defects are avoided because the first location and the second location are arranged at least partially spaced apart from each other.

[0031] In some embodiments of the method, the length of each of the two or more scan vectors is (i) equal to or greater than a minimum length, and / or (ii) equal to or less than a maximum length, to ensure that the energy input is not varied too much (i.e., too frequently) or not often enough, which could otherwise result in other defects in the solidified material layer.

[0032] In some embodiments of the method, a dimension of the area is equal to the difference between the maximum length and the minimum length. The area in which the first and second locations are located can be defined taking into account the minimum and maximum lengths of the scanning vector.

[0033] In some embodiments, the method further comprises irradiating the material layer with the radiation beam according to two or more scanning vectors.

[0034] In some embodiments of the method, the irradiation section is defined to include a contour area, in particular an overhanging contour area, of a workpiece to be manufactured from material layers using additive manufacturing. This advantageously avoids linear chain porosity and / or defects, in particular along the contour of the workpiece or in areas aligned with the contour. This reduces the extent to which support features are provided in the overhanging contour area of ​​the workpiece to be manufactured. The overhanging contour area is an area that lies above the unsolidified powder but not above the solidified part of the workpiece, also called the overhang or downskin.

[0035] In some embodiments of the method, the irradiation section is defined to include a base contour area of ​​the workpiece, which advantageously avoids linear chain porosity and / or defects, particularly in areas along or aligned with the contour of the workpiece. The base contour area is the area that is not within the solidified portion of the workpiece but is under the unsolidified powder after processing the subsequent layers, also known as the upskin.

[0036] In some embodiments of the method, an irradiation section is defined to include the overhanging contour area, and when the overhang angle of the overhanging contour area (defined relative to the vertical direction when the three-dimensional workpiece is manufactured layer by layer) is greater than a threshold angle, the irradiation includes unidirectional irradiation toward the overhanging contour. The threshold angle may depend on the material and / or layer thickness and / or irradiation source parameters, and may be, for example, less than 65 degrees, more preferably less than 50 degrees, and most preferably less than 40 degrees. This allows for uniform irradiation in the area including the overhanging contour area, thereby improving the quality of the workpiece in this area.

[0037] In some embodiments of the method, in the area where the overhang area is formed from the material layer, the start point of the scanning vector is located where the material in the layer immediately below the material layer has already solidified, and the end point of the scanning vector is located where the material in the layer immediately below the material layer has not solidified. If the start point of the scanning vector is located where the material in the layer immediately below the material layer that will be solidified according to the scanning vector has already solidified, defects and / or pores are not formed or are reduced compared to when the start point is located where the layer below the material layer that will be solidified has not solidified. This is because the non-solidified material basically acts as a separation layer, and the non-solidified material below the layer that will be solidified will cause the solidified layer (which is higher than the non-solidified material) to sink into the non-solidified layer. By preventing this, the quality of the workpiece can be improved.

[0038] In some embodiments of the method, when the irradiation includes bidirectional irradiation, the scan vector toward the center or central area of ​​the workpiece exceeds a threshold length and / or the irradiation energy density increases from the start of the scan vector to the end of the scan vector toward the center or central area of ​​the workpiece. The quality of the workpiece can thus be improved since anomalies (e.g. defects and / or pores) can be avoided. This is especially true for irradiation sections with a width below a threshold such that short scan vectors are merged with adjacent irradiation sections / scan vectors.

[0039] In some embodiments of the method, when the irradiation beam is scanned across the material layer at a location where the material below the material layer has already solidified but within a preset distance from the location where the material below the material layer has not yet solidified, the first and / or second locations of the change in irradiation energy density are defined on the material layer at the location where the material below the material layer has already solidified. As a result, there are no defects and / or porosity or there are fewer defects or porosity than if the location were at a location where the layer below the to-be-solidified material layer has not yet solidified. Thus, the quality of the workpiece can be improved. In some embodiments, two scanning vectors can be arranged back and forth in the irradiation section, where the irradiation energy density is reduced in the first vector in the area where the material below is solid, and the second scanning vector covers the overhanging area and starts with the reduced irradiation beam energy density.

[0040] Further, a method is described. - defining an irradiation section, in particular an irradiation stripe, on a material layer that is irradiated with a radiation beam scanned across the material layer in an additive manufacturing method; defining, within an illumination section, three or more parallel or substantially parallel scanning vectors for scanning the illumination beam across the material layer, where all scanning vectors within an illumination section are parallel or substantially parallel to one another; Including, Based on the three or more parallel or substantially parallel scanning vectors, a first location of a variation in irradiation energy density on the material layer of the irradiation beam for a first vector of three or more parallel or substantially parallel scanning vectors; a second location of variation in irradiation energy density on the material layer of the irradiation beam for a second vector of the three or more parallel or substantially parallel scanning vectors; a third location of variation in irradiation energy density on the material layer of the irradiation beam for a third vector of the three or more parallel or substantially parallel scanning vectors; is obtained, the first scan vector, the second scan vector, and the third scan vector are adjacent scan vectors, and the first location, the second location, and the third location are on the same side of a curve passing through the centers of the first scan vector, the second scan vector, and the third scan vector (respectively); a first line connects the first location and the second location, a second line connects the first location and the third location, The first and second lines are not parallel.

[0041] This method may be combined with any one or more of the example implementations described throughout this disclosure, and in particular with the method embodiments previously described.

[0042] In some embodiments of the method, the irradiation section is defined to include a contour area, in particular an overhang or base contour area, of a workpiece to be manufactured from material layers using additive manufacturing.

[0043] In some embodiments of the method, when the illumination section is defined to include the contour area, the first location, the second location and the third location relative to a curve passing through the centers of the first vector, the second vector and the third vector (respectively) are on the side of the curve opposite the contour of the workpiece.

[0044] In some embodiments of the method, all of the parallel ones of the first straight lines are non-tangent to the course of the workpiece contour and all of the parallel ones of the second straight lines are non-tangent to the course of the workpiece contour. In some embodiments of the method, all of the parallel ones of the first straight lines and all of the parallel ones of the second straight lines are non-tangent to the course of the workpiece contour.

[0045] Further described is a computer program product including program code portions for performing the methods outlined according to any one or more of the implementations described throughout this disclosure when the computer program product is executed on one or more computing devices. In some embodiments, the computer program product is stored on a computer-readable recording medium.

[0046] Further described is an apparatus for manufacturing a three-dimensional workpiece by additive manufacturing, the apparatus comprising: a carrier configured to receive material for manufacturing the three-dimensional workpiece, a material supply unit configured to supply material to the carrier and / or to one or more previous material layers on the carrier, a layer deposition mechanism for forming the supplied material into a material layer on the carrier and / or on one or more previous material layers on the carrier, a solidification device configured to solidify the material supplied to the carrier and / or to the one or more previous material layers on the carrier to manufacture the three-dimensional workpiece, a gas supply unit configured to supply shielding gas to an area of ​​the material layer to be solidified by the solidification device, a process chamber comprising the gas supply unit and the solidification device, and a computer-readable recording medium on which a computer program product as described above is stored.

[0047] The apparatus may be configured to implement the methods according to any one or more of the implementations described throughout this disclosure.

[0048] Further, a method is described that includes using an apparatus for manufacturing three-dimensional workpieces by additive manufacturing, in particular the above-mentioned apparatus, to provide data for implementing a method according to any one or more of the implementations described throughout this disclosure.

[0049] Further, a method for manufacturing a three-dimensional workpiece using additive additive manufacturing is described. The method includes defining an irradiation section, in particular an irradiation stripe, on a material layer irradiated with an irradiation beam scanned across the material layer using additive additive manufacturing, and defining one or more (e.g. parallel or substantially parallel) scanning vectors in the irradiation section for scanning the irradiation beam across the material layer, where the variation in irradiation beam energy density of the irradiation beam according to the scanning vector is located where the scanning vector is located in the first area of ​​the material layer where a layer below (e.g. immediately below) the material layer irradiated has already solidified and in a second area of ​​the material layer where a layer below (e.g. immediately below) the material layer irradiated has not solidified. The method can be combined with any one or more of the implementations of the method described throughout this disclosure. Defects or porosity can be prevented from occurring in the contour area of ​​the workpiece, thereby improving the quality of the manufactured workpiece.

[0050] These and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0051] [Figure 1] FIG. 1 is a schematic diagram of a scanning method according to the prior art. [Diagram 2] FIG. 2 is a schematic diagram of a scanning method according to the prior art. [Diagram 3] FIG. 3 is a schematic diagram of a scanning method according to implementations described throughout this disclosure. [Figure 4] FIG. 4 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Diagram 5] FIG. 5 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 6] FIG. 6 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 7]FIG. 7 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 8] FIG. 8 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 9] FIG. 9 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 10] FIG. 10 is a schematic diagram of another scanning method according to implementations described throughout this disclosure. [Figure 11] FIG. 11 is a flowchart of a method according to implementations described throughout this disclosure. [Figure 12] FIG. 12 is a schematic block diagram of an apparatus according to implementations described throughout this disclosure. [Figure 13] FIG. 13 is a flowchart of a method according to implementations described throughout this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] As outlined above, Figure 1 is a schematic diagram of a scanning method according to the prior art. In this example, the irradiated sections of the irradiated material layer have a square and a circular shape, respectively. It should be understood that other shapes are also possible.

[0053] In this example, the scan vector (arrow) is defined within an illumination stripe having a width 102. The length of the scan vector is defined according to the shape of the workpiece being manufactured.

[0054] As can be seen, the start and end points of the scan vectors are collinear for each of the two illustrated examples, and the inventors have determined that the locations 106 of potential pores and / or defects may be linearly arranged within the area 104.

[0055] FIG. 2 is a schematic diagram of another scanning method according to the prior art.

[0056] In this example, the layer 202 below the current layer being irradiated has solidified. In this example, an overhang 204 is produced due to the shape of the workpiece being manufactured using additive manufacturing.

[0057] As the illumination beam is scanned from position t0 to t2, the filling vector 206 shows a decrease in illumination energy density at t1. Similarly, the contour vector 208 shows a decrease in illumination energy density at position z1 and then increases again at position z4.

[0058] As can be seen, in the area where the overhang is created, the illumination beam energy density decreases for the area with the overhang.

[0059] In this example, the start and end points of the various vectors lie on a line (where position t0 is located in this example).

[0060] Even though the parameters were optimized to avoid defects between the stripes, chain pores repeatedly appeared in the solidified material layer.

[0061] Thus, implementations according to the present disclosure are particularly directed to scanning methods that allow for varying the width of the illumination stripe and / or the length of the scan vector according to some embodiments.

[0062] In general, the objective of the scanning method according to the implementations described in this specification is to ensure that the start and end points of adjacent vectors or points of change in irradiation energy density in adjacent vectors within a stripe are not directly adjacent to each other, and in some cases are as far apart as possible, and that the points are not arranged in a line across several scan vectors.

[0063] By varying the vector length within the area where the start and end points of the scanning vectors of a stripe or adjacent stripes are aligned (regardless of the shape of the workpiece being manufactured using additive manufacturing), rows of porosity or defects can be avoided, which can improve mechanical properties by reducing the potential for otherwise creating fracture points.

[0064] Furthermore, scanning methods of the type described herein can increase the tolerance to hardware or process effects. The effects of slightly varying beam diameters (from machine to machine) or varying melt pool sizes (which may result from various process effects such as short-term gas flow shortages and thus reduced absorption) can be minimized. Furthermore, the effects of different scanning vectors that are not synchronized with the movement of the irradiating beam are also minimized. Furthermore, variations in optics (e.g., scanning optics) and / or solidification equipment (e.g., lasers) can be advantageously offset.

[0065] FIG. 3 is a schematic diagram of a scanning method according to implementations described throughout this disclosure.

[0066] In this embodiment, irradiated sections 301a and 301b are defined within which the material layer will solidify.

[0067] Each illumination section is in the shape of a stripe, in this example having a stripe width 302 .

[0068] Within each of the illumination sections, a number of scan vectors are provided, each having a minimum vector length 304 and a maximum vector length 306.

[0069] In this embodiment, the start and end points of the scan vectors of the stripes are randomly distributed within the defined area 320 .

[0070] In this embodiment, an imaginary line 312 is formed between a start point 316 of scan vector 308 and a start point 318 of scan vector 310. In this embodiment, line 312 and scan vector 308 (and similarly line 312 and scan vector 310) form an angle 314 therebetween that is different than 90 degrees. In this embodiment, the angle is approximately 10 degrees.

[0071] In this embodiment, the size of the defined area 320 is determined by the defined minimum and maximum scan vector lengths.

[0072] Within the defined area 320, the start and end points of the scan vectors are randomly distributed so that the defects or voids are evenly distributed to avoid their linear arrangement.

[0073] FIG. 4 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0074] In this embodiment, the start and end points of the scan vectors move every other scan vector in a scan stripe having a width 402. Also in this embodiment, a minimum scan vector length 404 and a maximum scan vector length 406 are presented. The start and end points of the scan vectors are at the same height every other scan vector.

[0075] In this embodiment, closely spaced voids or defects can be reduced to some extent.

[0076] FIG. 5 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0077] In this embodiment, the start and end points of the scan vector lie on a sine wave in a scan stripe with width 502. Straight lines consisting of possible defects or voids can be avoided by using this scanning method.

[0078] Also in this embodiment, a minimum scan vector length 504 and a minimum scan vector length 506 are provided.

[0079] FIG. 6 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0080] In this embodiment, the start and end points of the scan vectors of the stripes having width 602 are arranged in a zigzag pattern. By offsetting every xth scan vector (every fourth scan vector in this embodiment), the linear array of pores or defects can be disrupted.

[0081] Also in this embodiment, a minimum scan vector length 604 and a maximum scan vector length 606 are presented.

[0082] Generally, in various implementations according to the present disclosure, in a defined area, the start and end points (located within a specific area of ​​the irradiation section) are distributed as evenly as possible. The start and / or end points of the scanning vector can be said to represent a change in the illumination beam energy density (from a first value different from zero to a second value different from zero that is greater than or less than the first value) along the scanning path of the scanning vector in any of the implementations described herein.

[0083] Using scanning methods according to implementations described herein, the distance between any defects or pores can be increased.

[0084] The scanning methods described herein may be particularly advantageous for overhanging contour areas of a workpiece manufactured using additive manufacturing methods. The manufacture of overhanging workpiece areas with close contours may be supported conventionally. Such support structures that must be added to the workpiece may increase powder consumption, increase manufacturing times, and increase post-machining effort of the workpiece.

[0085] Scanning according to the implementations described herein can reduce the support structure required by making scanning advantageous for use in (near) contour overhang areas. Certain scanning in solid parts of the workpiece can also help to eliminate anomalies.

[0086] Scanning methods according to implementations described throughout this disclosure can enable manufacturing of overhanging contour areas in particular to prevent aligned anomalies that may otherwise weaken workpiece components.

[0087] FIG. 7 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0088] In this embodiment, the scan stripe with width 702 covers the overhanging area, and the first portion includes the solidified layer below the layer to be irradiated (the dot area) and the unsolidified layer below the layer to be irradiated (the blank area).

[0089] As can be seen, in this embodiment, the irradiation beam energy density decreases once it crosses over an area with a layer of solidified material below the layer being irradiated (see irradiation beam energy density vs. filling vector location 706). The same applies to the contour vector 708, where the irradiation beam energy density decreases, for example, at location z1. For clarity of illustration, only one contour vector 708 is shown, but it should be understood that in some embodiments, the irradiation can follow more closely spaced paths at the workpiece contour, for example three parallel paths or five or more closely spaced paths. For vectors pointing away from the contour towards the interior of the workpiece, the irradiation beam energy does not increase until it crosses over an area with a layer of solidified material below the layer being irradiated.

[0090] FIG. 8 is a schematic diagram of a preferred scanning method according to different implementations described throughout this disclosure.

[0091] In this embodiment, for the illumination stripes covering the overhanging areas, the scanning vectors are defined to have varying start and end points in a wave pattern for at least some of the scanning vectors. In addition, the illumination beam energy density can be reduced in areas with an underlying non-solidified material layer, as shown in the embodiment of Figure 7. In particular, the illumination beam energy density of the scanning vectors of the illumination stripes covering the overhanging areas can be a constant energy density that is lower than the illumination beam energy density of the scanning vectors of the illumination stripes covering the solid material.

[0092] FIG. 9 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0093] In this embodiment, the scanning vectors are defined to be aligned in one direction along the contour of the workpiece. The scanning method of FIG.

[0094] FIG. 10 is a schematic diagram of a scanning method according to another implementation described throughout this disclosure.

[0095] In this embodiment, the irradiation stripe covering the overhanging area includes scan vectors arranged partially back and forth, and a second scan vector covering the contour of the workpiece is defined to have a smaller irradiation energy density compared to the first scan vector arranged entirely over the area with solidified material below the layer being irradiated.

[0096] Based on the above embodiment, the filling vectors can be defined as adjacent scanning vectors in the illumination stripe that have different locations of illumination energy density change (e.g., start and / or end points of the scanning vectors) depending on the shape of the structure, which can result in, for example, different lengths and / or start and / or end points of the scanning vectors.

[0097] In some embodiments, the length, start and / or end points can be defined randomly as described above or in a specific pattern (e.g., sinusoidal with arbitrary amplitude and frequency), which can be particularly advantageous for illumination stripes located along an overhanging profile.

[0098] When carried out along an overhanging contour area, it is preferred to arrange several illumination stripes according to the present disclosure next to each other.

[0099] Although the illustrated embodiment includes the same number of vectors with the same distance in adjacent irradiated areas or irradiated stripes, it should be understood that the irradiated areas can include different numbers of vectors with different distances to vary the irradiated energy density between the irradiated areas. In particular, the irradiated areas in the overhanging contour areas can include a different number of vectors than the irradiated areas on the solid material. It should also be apparent that (alternatively or in addition) other parameters can be varied to control the irradiated energy density as described above.

[0100] Bidirectional irradiation up to a certain overhang angle and then unidirectional irradiation in the direction of the workpiece contour may be preferred, as this allows for uniform irradiation in the area of ​​the workpiece contour, thereby improving the quality of the workpiece.

[0101] To avoid problems with continuous initial superelevation or anomalies, different starting (and / or ending) points can be selected for a particular one-way scan vector.

[0102] An abrupt decrease in the illumination beam power / energy density in the area in front of the overhanging contour area at different points of adjacent scan vectors may be preferred to avoid a linear array of possible voids or defects.

[0103] Alternatively or in addition to reducing the illumination beam power, the scan vector can be split into two scan vectors that are illuminated one after the other, with the first vector being exposed to normal illumination beam power and the subsequent vector being exposed to reduced illumination beam power.

[0104] In case of bidirectional irradiation, it may be preferable to select a long scanning vector for irradiation towards the inner / central part of the workpiece: relatively shallow irradiation sections / stripes can thus be avoided, thereby distributing possible defects or porosity as much as possible.

[0105] For bi-directional illumination, the illumination beam energy density for scan vectors pointing inward away from the workpiece contour may increase beyond a certain location, which may be similar to the decrease for scan vectors pointing outward from the workpiece contour.

[0106] In the case of an external contour, in the most general case, the contour may extend along an area with a solidified base / layer as well as along an area with a layer that is not yet solidified underneath. In the transition between these contour areas, the irradiation beam power / energy density may be changed according to the procedure for hatching in a scanning method for manufacturing a workpiece using additive manufacturing. If the impact point of the energy irradiation is near the transition in the solid part (i.e. the material below the layer being irradiated is solid) to the area that is not yet solidified (below the layer being irradiated), the irradiation beam power may still be changed in the solid part of the contour irradiation. If the location of the energy irradiation is in an area that is not yet solidified and the transition to a solidified area is imminent, the irradiation beam power may be changed to the normal value for the solid area - this can be applied to the filling vector and / or the contour vector. To ensure that the transition of each layer is made at various locations of the solid sub-area, the location may vary from layer to layer, whereby the distance of the energy density input change location from the actual transition location of the contour area from the solid area to the non-solidified area is different from zero.

[0107] The scanning method according to the implementations described herein avoids anomalies along the hatch boundaries, thus allowing for a more homogenous material structure and avoiding defects or voids in the linear arrays in particular.

[0108] FIG. 11 is a flowchart of a method 1100 according to implementations described throughout this disclosure.

[0109] In this embodiment, an irradiation section is defined in step S1102 on a material layer that is irradiated with an irradiation beam that is scanned across the material layer in an additive manufacturing process.

[0110] In step S1104, two or more parallel or substantially parallel scan vectors for scanning the illumination beam across a material layer are defined within the illumination section.

[0111] By defining two or more parallel or substantially parallel scan vectors as above, a line is defined connecting a first location of a change in irradiance energy density of the irradiation beam on the material layer for a first of the two or more parallel or substantially parallel scan vectors to a second location of a change in irradiance energy density of the irradiation beam on the material layer for a second of the two or more parallel or substantially parallel scan vectors, the first and second scan vectors being adjacent scan vectors, the distance between the first location and the second location being smaller than (i) a distance between the first location and a third location of a change in irradiance energy density of the irradiation beam for the second of the two or more parallel or substantially parallel scan vectors and / or (ii) a distance between the second location and a fourth location of a change in irradiance energy density of the irradiation beam for the first of the two or more parallel or substantially parallel scan vectors, and an angle different from 90 degrees is formed (i) between the first scan vector and the line and / or (ii) between the second scan vector and the line regardless of the shape of a workpiece manufactured using additive manufacturing. In some embodiments, after defining one or more hatches that are subsequently filled with one or more scan vectors, the length of the one or more scan vectors is checked, and the one or more hatches can then be adjusted to avoid the scan vector having a length below a preset threshold.

[0112] In step S1106, the material layer is irradiated according to two or more defined scan vectors.

[0113] FIG. 12 is a schematic block diagram of an apparatus 1200 according to implementations described throughout this disclosure.

[0114] In this embodiment, the apparatus 1200 is used to manufacture a three-dimensional workpiece by additive manufacturing.

[0115] The apparatus 1200 comprises a carrier 1202 configured to receive material for manufacturing a three-dimensional workpiece. The apparatus 1200 further comprises a material supply unit 1204 configured to supply material to the carrier 1202 and / or to one or more previous material layers on the carrier 1202.

[0116] A layer deposition mechanism 1206 is provided to form the dispensed material into a material layer on the carrier 1202 and / or one or more previous material layers on the carrier 1202 .

[0117] Apparatus 1200, in this embodiment, further comprises a solidification device 1208 configured to solidify material provided on carrier 1202 and / or one or more prior material layers on carrier 1202 to produce the three-dimensional workpiece. Solidification device 1208 can comprise one or more lasers and / or one or more particle (e.g., electron) beam sources.

[0118] The apparatus 1200 , in this embodiment, further comprises a gas supply unit 1210 configured to supply a shielding gas to the area of ​​the material layer being solidified by the solidification device 1208 .

[0119] The apparatus 1200, in this embodiment, further comprises a process chamber 1212 in which a three-dimensional workpiece can be manufactured using additive manufacturing. In some embodiments, the carrier 1202 and / or the material supply unit 1204 and / or the layer deposition mechanism 1206 and / or the solidification device 1208 and / or the gas supply unit 1210 can be located within the process chamber 1212.

[0120] The apparatus 1200, in this embodiment, further comprises a computer-readable recording medium 1214 including a computer program product comprising program code portions for performing a method according to any one of the implementations described herein when the computer program product is executed on one or more computing devices.

[0121] FIG. 13 is a flowchart of a method 1300 according to implementations described throughout this disclosure.

[0122] In this embodiment, the illumination segments and scan vectors are defined as outlined above in steps S1102 and S1104 of method 1100. Method 1300 further includes providing data for implementing a method according to any one of the implementations as described herein using an apparatus for manufacturing a three-dimensional workpiece by additive manufacturing, particularly the apparatus shown in FIG.

[0123] Undoubtedly, many other effective solutions will be apparent to those skilled in the art. It should be understood that the present invention is not limited to the described embodiments and implementations, but encompasses modifications that are obvious to those skilled in the art and that fall within the scope of the claims appended hereto.

Claims

1. 1. A method comprising: - defining an irradiation section, in particular an irradiation stripe, on a material layer that is irradiated with a beam of radiation that is scanned across the material layer in an additive manufacturing process; defining two or more parallel or substantially parallel scan vectors within the illumination section for scanning the illumination beam across the material layer, wherein all scan vectors within the illumination section are parallel or substantially parallel to one another; Including, Based on said defining of said two or more parallel or substantially parallel scanning vectors, a first location of a variation in irradiation energy density of the irradiation beam on the material layer for a first scan vector of the two or more parallel or substantially parallel scan vectors; a second location of variation in irradiation energy density of the irradiation beam on the material layer for a second scan vector of the two or more parallel or substantially parallel scan vectors; A line connecting the first scanning vector and the second scanning vector are adjacent scanning vectors, and the distance between the first location and the second location is smaller than (i) a distance between the first location and a third location of the change in irradiance energy density of the irradiation beam for the second scanning vector of the two or more parallel or substantially parallel scanning vectors, and / or (ii) a distance between the second location and a fourth location of the change in irradiance energy density of the irradiation beam for the first scanning vector of the two or more parallel or substantially parallel scanning vectors; Angle other than 90 degrees (a) regardless of the shape of the workpiece produced using said additive manufacturing method; and (b) regardless of the orientation of the two or more parallel or substantially parallel scanning vectors relative to the orientation of the illumination section; (i) formed between the first scanning vector and the line, and / or (ii) formed between the second scanning vector and the line; the method further comprising irradiating the material layer with the irradiation beam according to the two or more scanning vectors; the illumination section is defined to include a contour area of ​​the workpiece to be manufactured from the material layers using the additive manufacturing method; a starting point of the scanning vector in the area where the contour is formed from the material layer is located at a point where material has already solidified in the layer immediately below the material layer, and an end point of the scanning vector is located at a point where material has not solidified in the layer immediately below the material layer. method.

2. The method described in claim 1, wherein the angle different from 90 degrees is formed based on adjacent scan vectors of each pair of the two or more scan vectors.

3. A method as described in claim 1 or 2, wherein the angle differs from 90 degrees by at least 5 degrees, preferably by at least 10 degrees, and more preferably by at least 15 degrees.

4. A method described in any one of claims 1 to 3, wherein the change in irradiation energy density includes the start point and / or end point of the scanning vector at each of the locations.

5. The angle formed to be different from 90 degrees is a) the first scan vector and the second scan vector of the two or more parallel or substantially parallel scan vectors; (i) different lengths and / or (ii) each having a different starting point and / or (iii) Each different end point and / or b) the starting point of one of the first and second scan vectors is different from the ending point of the other of the first and second scan vectors; Based on The method according to any one of claims 1 to 4.

6. A method according to any one of claims 1 to 5, further comprising defining an area within the irradiation section, wherein the first location and the second location are located within the area along respective straight lines on which the respective first scanning vectors of the two or more scanning vectors and the respective second scanning vectors of the two or more scanning vectors are defined.

7. The method described in claim 6, wherein the first location and the second location are randomly arranged within the area.

8. The method of claim 6, wherein the locations are evenly distributed within the area.

9. The method of claim 6, wherein the connecting lines of the locations of every other scanning vector form a straight line.

10. The method of claim 6, wherein the locations are located on the material layer according to a wave-like curve, particularly a sinusoidal curve.

11. The method of claim 6, wherein the locations are located on the material layer according to a zigzag pattern.

12. A method described in any one of claims 1 to 11, wherein the distance between the first location and the second location exceeds a preset threshold.

13. A method according to any one of claims 1 to 12, wherein each of the two or more lengths is (i) equal to or greater than a minimum length, and / or (ii) equal to or less than a maximum length.

14. A method as claimed in claim 13, when dependent on claim 6, wherein the dimension of the area is equal to the difference between the maximum length and the minimum length.

15. A method described in any one of claims 1 to 14, wherein when the irradiation section is defined to include the protruding contour area and the protruding angle of the protruding contour area exceeds a threshold angle, the irradiation includes unidirectional irradiation toward the protruding contour.

16. A method described in any one of claims 1 to 15, wherein when the irradiation includes bidirectional irradiation, the length of the scanning vector toward the center or central region of the workpiece exceeds a threshold length, and / or the irradiation energy density increases from the start point of the scanning vector toward the center or central region of the workpiece to the end point of the scanning vector.

17. A method according to any one of claims 1 to 16, wherein when the irradiation beam is scanned across the material layer at a location within a preset distance from a location where the material below the material layer has already solidified but where the material below the material layer has not yet solidified, the first location and / or second location of variation in irradiation energy density is defined on the material layer at the location where the material below the material layer has already solidified.

18. A method for producing a three-dimensional workpiece using additive manufacturing, the method comprising: - defining irradiation sections, in particular irradiation stripes, on a material layer that is irradiated with an irradiation beam scanned across said material layer using said additive manufacturing method; defining one or more scan vectors within the irradiation section for scanning the irradiation beam across the material layer, wherein when the scan vector is in a first area of ​​the material layer where a layer immediately or indirectly below the material layer being irradiated has already solidified and in a second area of ​​the material layer where the layer immediately or indirectly below the material layer being irradiated has not yet solidified, a variation in irradiation beam energy density of the irradiation beam according to the scan vector is located where the scan vector is in the first area; A method comprising:

19. An apparatus for producing a three-dimensional workpiece by additive manufacturing, said apparatus comprising: a carrier configured to receive material for producing the three-dimensional workpiece; a material supply unit configured to supply material to the carrier and / or one or more preceding material layers on the carrier; a layer deposition mechanism for forming the supplied material into a material layer on the carrier and / or the one or more previous material layers on the carrier; a solidification device configured to solidify the material supplied to the carrier and / or the one or more previous material layers on the carrier to produce the three-dimensional workpiece; a gas supply unit configured to supply a shielding gas to an area of ​​the material layer being solidified by the solidification device; a process chamber including the gas supply unit and the solidification device; a computer-readable recording medium containing a computer program product; Equipped with the computer program product includes program code portions for performing a method when the computer program product is executed on one or more computing devices; The method comprises: - defining irradiation sections, in particular irradiation stripes, on a material layer that is irradiated with an irradiation beam scanned across the material layer using the additive manufacturing method; defining, within the section, two or more parallel or substantially parallel scan vectors for scanning the illumination beam across the material layer, wherein all scan vectors within the illumination section are parallel or substantially parallel to one another; Including, Based on said defining of said two or more parallel or substantially parallel scanning vectors, a first location of a variation in irradiation energy density of the irradiation beam on the material layer for a first vector of the two or more parallel or substantially parallel scanning vectors; a second location of variation in irradiation energy density of the irradiation beam on the material layer for a second vector of the two or more parallel or substantially parallel scanning vectors; A line connecting the first scanning vector and the second scanning vector are adjacent scanning vectors, and the distance between the first location and the second location is smaller than (i) a distance between the first location and a third location of the change in irradiance energy density of the irradiation beam for a second vector of the two or more parallel or substantially parallel scanning vectors, and / or (ii) a distance between the second location and a fourth location of the change in irradiance energy density of the irradiation beam for a first vector of the two or more parallel or substantially parallel scanning vectors; Angle other than 90 degrees (a) regardless of the shape of the workpiece produced using said additive manufacturing method; and (b) regardless of the orientation of the two or more parallel or substantially parallel scanning vectors relative to the orientation of the illumination section; (i) formed between the first scanning vector and the line, and / or (ii) formed between the second scanning vector and the line; the method further comprising irradiating the material layer with the irradiation beam according to the two or more scanning vectors; the irradiation section is defined to include a contour area, in particular an overhang or base contour area, of the workpiece to be manufactured from the material layers using the additive manufacturing method, a starting point of the scanning vector in the area where the contour is formed from the material layer is located at a point where material has already solidified in the layer immediately below the material layer, and an end point of the scanning vector is located at a point where material has not solidified in the layer immediately below the material layer. Device.

20. A method comprising using an apparatus for producing a three-dimensional workpiece by additive manufacturing, in particular the apparatus described in claim 19, to provide data for realizing a method according to any one of claims 1 to 18.

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