System and method for constructing large single-crystal objects using segmented scanning patterns

Abstract

Segmented scanning patterns generate 3D printed metal objects with large cubic structures. The first patterned layer is generated by moving a molten pool within the first powder layer along a first layer scanning pattern that includes the first section of the first layer, the second section of the first layer, and the first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. The second patterned layer is generated by moving a molten pool within the second powder layer along a second layer scanning pattern that includes the first section of the second layer, the second section of the second layer, and the first overlap of the second layer where the first section of the second layer and the second section of the second layer intersect. The first overlap of the second layer overlaps on top of the first section of the first layer or the second section of the first layer. The first overlap of the second layer does not overlap on top of the first overlap of the first layer.

Description

Technical Field

[0001] Cross - reference to Related Applications This patent application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 511,155, entitled "SYSTEMS AND METHODS FOR USING A SEGMENTED SCAN PATTERN TO BUILD LARGE SINGLE CRYSTAL OBJECTS," filed on June 29, 2023.

[0002] The described aspects generally relate to additive manufacturing, 3D printing, selective laser melting (SLM) printing of 3D objects, and 3D printing of cubic materials. These aspects also relate to controlling the shape and overlap of melt pools, thereby forming a directional and single - crystal microstructure in 3D printed objects.

Background Art

[0003] Objects can be fabricated with 3D printers using various techniques such as stereolithography (SLA), selective laser melting (SLM), selective laser sintering (SLS), fused deposition modeling (FDM), direct metal printing (DMP), electron beam melting (EBM), directed energy deposition (DED), and laser bed powder fusion (LBPF). This field is developing rapidly, with new techniques being developed and known techniques being continuously improved. Many techniques work by forming patterned material layers on a substrate and then forming additional layers on top of the previously formed layers. Some techniques (e.g., DED) create patterned layers by generating a molten pool and then adding material to the molten pool while moving it. Some techniques (e.g., SLM, EBPF) create patterned layers by depositing layers of powder material and then selectively melting that powder material to create patterned layers of solid material. The materials used in additive manufacturing are often cubic materials. Cubic materials are, <100> It is a material that forms a cubic crystal structure with orientation.

[0004] Additive manufacturing is a technology with a history of only a few decades, while classical manufacturing processes have existed for thousands of years. For example, the Bronze Age began about 5,000 years ago, and the Iron Age began 3,000 years ago. Classical processes are highly sophisticated because they have been studied and refined for thousands of years. There is a need for systems and methods to produce additive products that meet or exceed the material properties exhibited by objects manufactured using classical processes. [Overview of the project]

[0005] The following summary is provided to facilitate understanding of some of the innovative features specific to the disclosed example and is not intended as a complete description. Various aspects of the example can be fully grasped by comprehensively referring to the specification, claims, drawings, and abstract as a whole.

[0006] One aspect of the subject matter described herein can be implemented by method. This method may include the step of depositing a first powder layer. This method may further include the step of generating a first patterned layer by moving a molten pool in the first powder layer along a first layer scanning pattern including a first section of the first layer, a second section of the first layer, and a first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. This method may further include the steps of depositing a second powder layer on the first patterned layer, generating a second patterned layer by moving a molten pool in the second powder layer along a second layer scanning pattern, depositing a third powder layer on the second patterned layer, and generating a third patterned layer by moving a molten pool in the third powder layer along a third layer scanning pattern including a first section of the third layer, a second section of the third layer, and a first overlap of the third layer where the first section of the third layer and the second section of the third layer intersect. The third layer's first overlap overlaps the first section of the first layer or the second section of the first layer, but the third layer's first overlap does not overlap the first overlap of the first layer.

[0007] Another aspect of the subject matter described herein can be implemented by a system. This system may include a powder feeder configured to generate a first powder layer and a second powder layer by depositing powder on a powder bed, a beam source configured to generate a molten pool in the powder, and a beam scanner configured to generate a first patterned layer and a second patterned layer by moving the molten pool relative to the powder bed. The first patterned layer is generated by moving a molten pool within the first powder layer along a first layer scanning pattern that includes the first section of the first layer, the second section of the first layer, and the first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. The second patterned layer is generated by moving a molten pool within the second powder layer along a second layer scanning pattern that includes the first section of the second layer, the second section of the second layer, and the first overlap of the second layer where the first section of the second layer and the second section of the second layer intersect. The first overlap of the second layer overlaps the first section of the first layer or the second section of the first layer, while the first overlap of the second layer does not overlap the first overlap of the first layer.

[0008] Another aspect of the subject matter described herein can be implemented by a system. This system may include a deposition means for depositing powder to generate a plurality of powder layers, and a patterning means for generating a plurality of patterned layers by moving a molten pool within the powder. A first patterned layer among the plurality of patterned layers is generated by moving a molten pool within the first powder layer among the plurality of powder layers along a first layer scanning pattern including a first section of the first layer, a second section of the first layer, and a first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. A second patterned layer among the plurality of patterned layers is generated by moving a molten pool within the second powder layer among the plurality of powder layers along a second layer scanning pattern. A third patterned layer among the plurality of patterned layers is generated by moving a molten pool within the third powder layer along a third layer scanning pattern including a first section of the third layer, a second section of the third layer, and a first overlap of the third layer where the first section of the third layer and the second section of the third layer intersect. The second patterned layer of the multiple patterned layers lies above the first patterned layer and below the third patterned layer, while the first overlap of the third layer does not overlap the first overlap of the first layer.

[0009] In some implementations of the method and apparatus, the first layer scanning pattern includes multiple first layer sections and multiple first layer overlaps in which one of the first layer sections intersects with another of the first layer sections, and the third layer scanning pattern includes multiple third layer sections and multiple third layer overlaps in which one of the third layer sections intersects with another of the third layer sections, the third layer sections overlapping on top of the first layer sections, and none of the third layer overlaps overlap with any of the first layer overlaps. In some implementations of the method and apparatus, the growth of stray crystals in a first layer overlap is suppressed by passing the molten pool twice through the first layer overlap. In some implementations of the method and apparatus, the first layer first section includes a first scanning line segment, and the molten pool extends along the entire length of the first scanning line segment after the molten pool has been moved along the first scanning line segment. In some implementations of the method and apparatus, the first layer first section includes a first scanning line segment and a second scanning line segment, and the molten pool extends along the entire length of the first scanning line segment after the molten pool has moved along the first scanning line segment. The molten pool is moved along the second scanning line segment immediately after the molten pool has moved along the first scanning line segment, and the molten pool does not extend along the entire length of the first scanning line segment after the molten pool has moved along the second scanning line segment.

[0010] In some implementations of the method and apparatus, the first layer, first section includes a first scanning line segment and a second scanning line segment, and the molten pool extends along the entire length of the first scanning line segment after the molten pool has moved along the first scanning line segment, and immediately after the molten pool has moved along the first scanning line segment, it moves along the second scanning line segment, and the molten pool does not extend along the entire length of the first scanning line segment after the molten pool has moved along the second scanning line segment, and the molten pool extends from the second scanning line segment to the first scanning line segment by lateral heating. In some implementations of the method and apparatus, multiple lengths of multiple scanning line segments are used to set the beam power of the energy beam that generates the molten pool. In some implementations of the method and apparatus, a map associates multiple scanning line lengths with multiple beam power values, and multiple lengths of multiple scanning line segments are used to set the beam power of the energy beam that generates the molten pool according to the map. In some implementations of the method and apparatus, the first scanning line segment and the second scanning line segment have different lengths, so the beam power when scanning the first scanning line segment is not equal to the beam power when scanning the second scanning line segment.

[0011] In some implementations of the method and apparatus, the first layer, first section includes multiple scanning line segments having multiple lengths, and the multiple lengths of the multiple scanning line segments are used to set the scanning speed of the energy beam that generates the molten pool. In some implementations of the method and apparatus, the scanning speed has a first velocity value when scanning the first scanning line segment of the multiple scanning line segments, and the scanning speed has a second velocity value when scanning the second scanning line segment of the multiple scanning line segments, and the first velocity value is not equal to the second velocity value because the first scanning line segment and the second scanning line segment of the multiple scanning line segments have different lengths. In some implementations of the method and apparatus, a map associates multiple scanning line lengths with multiple scanning speed values, and the first layer, first section includes multiple scanning line segments having multiple lengths, and the multiple lengths of the multiple scanning line segments are used to set the scanning speed according to the map. In some implementations of the method and apparatus, an energy beam is scanned, thereby moving the molten pool, and the energy beam has scanning speed and beam power, and a series of molten pool images show the molten pool shape, and the scanning speed or beam power is adaptively controlled to obtain a molten pool shape that is a desired molten pool shape.

[0012] In some implementations of the method and apparatus, the first layer includes a first scanning line segment and a second scanning line segment parallel to the first scanning line segment, and the molten pool extends along the entire length of the first line segment after the molten pool has moved along the first scanning line segment. The molten pool is moved along the second scanning line segment immediately after the molten pool has moved along the first scanning line segment, and the molten pool does not extend along the entire length of the first line segment after the molten pool has moved along the second scanning line segment, and the molten pool extends from the second scanning line segment to the first line segment by lateral heating. In some implementations of the method and apparatus, multiple lengths of multiple scanning line segments are used to set the power of the beam source or the scanning speed of the molten pool. In some implementations of the method and apparatus, the third layer first overlap overlaps the first section of the first layer or the second section of the first layer. In some implementations of the method and apparatus, the growth of stray crystals is suppressed by passing the molten pool twice within the first layer first overlap. [Brief explanation of the drawing]

[0013] Similar reference numerals refer to the same or functionally similar elements throughout the individual figures, and the accompanying drawings incorporated herein and forming part thereof further illustrate examples and, together with detailed descriptions, are helpful in illustrating the examples disclosed herein.

[0014] [Figure 1] Figure 1 is a high-level conceptual diagram of an SLM-style 3D printer relating to several embodiments. [Figure 2] Figure 2 is a high-level conceptual diagram showing scanning patterns and molten pools in several embodiments. [Figure 3] Figure 3 is a high-level conceptual diagram showing segmented scanning patterns in several embodiments. [Figure 4] Figure 4 is a high-level conceptual diagram showing the movement of a molten pool along a segmented scanning pattern in several embodiments. [Figure 5] Figure 5 is a high-level conceptual diagram illustrating, in several embodiments, that overlaps within one layer do not overlap with overlaps within another layer. [Figure 6] Figure 6 is a high-level conceptual diagram showing a control system for controlling a beam scanner and beam source in several embodiments. [Figure 7] Figure 7 is a high-level conceptual diagram showing maps relating different scanning line lengths to different beam power or scanning speeds in several embodiments. [Figure 8] Figure 8 is a high-level conceptual diagram illustrating adaptive control of scanning speed or beam power to obtain a desired molten pool shape, relating to several embodiments. [Modes for carrying out the invention]

[0015] The specific values ​​and configurations discussed in the following non-restrictive examples are subject to change and are cited merely to illustrate one or more examples, and are not intended to limit their scope.

[0016] Examples will be described in more detail below with reference to the attached drawings. The examples disclosed herein can be embodied in different forms and should not be construed as limiting the scope of the claims, but rather these examples are provided to ensure that this disclosure is sufficient and complete and to fully convey the scope of the claims to those skilled in the art. Similar numbers refer to similar elements throughout. An apparatus configured to produce a certain result may produce that result during the operation of the apparatus.

[0017] The terms used herein are intended solely to illustrate specific examples and are not intended to be limiting. Where used herein, the singular forms "a," "an," and "the" are intended to include the plural form unless the context clearly indicates otherwise. Furthermore, where used herein, the terms "comprise" or "comprising" specify the presence of a described feature, component, step, operation, element, or component, but it will be understood that this does not preclude the presence or addition of one or more other features, components, steps, operations, elements, components, or groups thereof.

[0018] Throughout this specification and the claims, terms may have nuances implied or suggested in context beyond their expressly stated meaning. Similarly, the expression “in one example” as used herein does not necessarily refer to the same example, and the expression “in another example” as used herein does not necessarily refer to a different example. The claimed subject matter is intended to include combinations of examples.

[0019] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art. Terms as defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and it will be further understood that they should not be interpreted in such a sense unless explicitly defined herein in an idealized or overly formal sense.

[0020] It will be understood that the examples described in this specification are illustrative and not limiting. These aspects can be used in various examples without departing from the scope of the claims. A person skilled in the art will be able to recognize or confirm numerous equivalents to the specific procedures described herein using only routine experimentation. Such equivalents are considered to be within the scope of the claims.

[0021] The use of the term "a" or "an" when used in combination with the term "comprising" in the claims or this specification may mean "one", but is also consistent with the meanings of "one or more", "at least one", and "one or more". The use of the term "or" in the claims implicitly includes "and" unless expressly indicated otherwise. Throughout this application, the term "about" indicates that a value includes inherent variations due to errors specific to the device, variations resulting from the method used to determine that value, or variations inherent among subjects.

[0022] As used in this specification and the claims, the terms "comprising" (including derivatives such as "comprise" and "comprises"), "having" (including derivatives such as "have" and "has"), "including" (including derivatives such as "includes" and "include"), or "containing" (including derivatives such as "contains" and "contain") are inclusive or open-ended and do not exclude additional unrecited elements or method steps.

[0023] As used herein, the term "or combinations thereof" refers to all permutations and combinations of the items listed prior to that term. For example, "A, B, C, or combinations thereof" is intended to include at least one of A, B, C, AB, AC, BC, or ABC, and where order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, combinations that include repeats of one or more items or terms are explicitly included, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, etc. One of ordinary skill in the art will understand that, unless otherwise apparent from the context, there is usually no limit to the number of items or terms in any combination.

[0024] The systems and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. Although the systems and methods have been described by way of example, it will be apparent to one of ordinary skill in the art that changes can be applied to the systems and methods, as well as to the steps or series of steps of the methods described herein, without departing from the spirit, purport, and scope of the claims. All such similar alternatives and modifications that are apparent to one of ordinary skill in the art are considered to be within the spirit, scope, and concept of the claims.

[0025] Figure 1 is a high-level conceptual diagram of an example of an SLM-type 3D printer 100 relating to several embodiments. The powder supply device can be configured to generate a powder layer in the powder bed. In this example, the powder supply device 110 deposits powder 112 to generate a powder layer 105 in the powder bed 108. The first powder layer to be deposited, i.e., the initial layer, can be placed directly on the powder bed or on a substrate that can be placed in the powder bed before the powder layer is deposited. The beam source may be configured to generate a molten pool by generating an energy beam that melts a portion of the powder, thereby creating a molten pool. The beam scanner can be configured to generate patterned layers by moving the molten pool. In this example, the beam scanner 101 can move the beam source 102 or direct the energy beam 111 generated by the beam source 102. The energy beam may be a laser beam, an electron beam, etc. The energy beam 111 generates a molten pool 104 in which the energy beam 111 melts a portion of the powder in the powder bed 108. The molten pool 104 has a molten pool depth 103. The molten pool depth 103 is indicated as being large enough to also melt a portion of the patterned layer 106 directly below the powder layer 105. In some implementations, the molten pool can extend downward through multiple lower layers. The beam scanner moves the molten pool 104 along a path through the uppermost powder layer to selectively melt a portion of the powder, thereby creating a patterned layer. The first deposited powder layer becomes the bottom patterned layer 107. A 3D object is fabricated by repeatedly depositing powder layers and using an energy beam to melt patterns within the powder layers, thereby creating patterned layers.

[0026] Figure 2 is a high-level conceptual diagram showing a scanning pattern and molten pool in several embodiments. A powder layer 201 is deposited and ready to be patterned by moving the molten pool along a scanning pattern 206. The scanning pattern has a first scanning line 207, a second scanning line 208, and so on. In Figure 2, the first scanning line of the scanning pattern 206 is shown as the first scanning line, but any scanning line can be called the first scanning line or the second scanning line. The scanning pattern 206 shown in Figure 2 is a bidirectional scanning pattern in which the scanning direction changes by 180 degrees from one scanning line to the next. A molten pool can be generated by moving an energy beam (e.g., a laser beam, an electron beam, etc.) along the scanning pattern. The energy beam completely melts the material in the region of the layer, creating a completely molten molten pool region 202. The material cools rapidly, and as the molten pool cools, crystal grains or dendritic crystals grow within the molten pool. The partially molten molten pool region 203 is the portion of the molten pool in which crystal grains or dendritic crystals are growing. Thus, the molten pool 104 may contain both a completely molten molten pool region and a partially molten molten pool region. The patterned region 204 is the region where the molten pool has solidified. The patterned layer 205 is generated by moving the molten pool along a scanning pattern 206 and allowing the molten pool to solidify. In the figures herein, as seen in Figure 2, the completely molten molten pool region 202 is shown as a black region and the partially molten molten pool region 203 is shown as a gray region.

[0027] Figure 3 is a high-level conceptual diagram showing a segmented scanning pattern 301 in several embodiments. A segmented scanning pattern may have two or more sections and one or more overlaps. An overlap is the region where one section intersects with another section. The scanning pattern 301 shown in Figure 3 is a unidirectional scanning pattern in which the scanning direction is the same from one scanning line segment to the next. The scanning pattern 301 includes a first section 302 and a second section 303. A non-limiting example shown in Figure 3 shows the second section 303 being scanned after the first section 302. In practice, either section may be scanned first. Furthermore, as shown in Figure 3, one of the sections does not need to be scanned immediately after the other section. The first overlap 304 is the region where the first section 302 and the second section 303 intersect. The molten pool passes through the first overlap 304 when moving along the first section 302 of the scanning pattern, and also passes through the first overlap 304 when moving along the second section 303 of the scanning pattern. Therefore, the material within the first overlap 304 can be completely melted twice by the energy beam. The molten pool passes through the first overlap twice to suppress the growth of stray crystals at the intersection of the first and second sections. An example of a stray crystal is a dendritic crystal that grows from the end of a scanning line segment in a direction parallel to the scanning line direction. By melting the overlap region twice, the growth of such stray crystals can be suppressed.

[0028] Figure 4 is a high-level conceptual diagram showing the movement of a molten pool along a segmented scanning pattern in several embodiments. The scanning pattern has a first section 401, a second section 402, and a third section 403. In the non-limiting example of Figure 4, the molten pool is scanned through the first section 401, then through the second section 402, and then through the third section 403. The powder layer 400 is not yet patterned in sections that the molten pool has not passed through. After the molten pool moves along each line segment, it can be seen that the molten pool extends along the entire length of that line segment. It is important that the molten pool melts the entire line segment because melting the entire line segment promotes the growth of large crystal structures. The problem here is that the length of the molten pool is limited because the molten pool cools rapidly. By segmenting the scanning pattern, sections are created in which the molten pool extends along the entire line segment, thereby promoting the growth of large crystal structures. It can also be seen that each section has multiple scanning line segments. The molten pool can move along the first line segment and then immediately along the second line segment adjacent to the first line segment. The molten pool extends along the entire length of the first line segment after it has moved along the first scanning line segment, although that portion of the molten pool is rapidly solidifying and may solidify completely before it has fully moved along the second line segment. Therefore, the molten pool may not extend along the entire length of the first line segment after it has moved along the second scanning line segment. However, as shown in Figure 4, the molten pool can extend from the second line segment to the first line segment due to lateral heating. Lateral heating occurs when the heat from the molten pool moves laterally into the material near the molten pool. Melting or keeping the previously scanned lines molten is important because it promotes the growth of crystalline structures from one scanning line segment to the next.The required lateral heating is another limiting factor for the scanning line length, because previously scanned line segments need to remain at a high temperature to be maintained in a molten state or sufficiently melted by lateral heating.

[0029] The first overlap 406 is where the first section 401 and the second section 402 intersect. The second overlap 407 is where the second section 402 and the third section 403 intersect. As described above, the material within the overlap is melted twice by the energy beam. Thus, the crystalline structure growing in the patterned first section can grow in the patterned second section. After the molten pool has completely moved along all line segments of all sections and the layer has completely solidified, the patterned layer 405 remains.

[0030] Figure 5 is a high-level conceptual diagram showing that the overlap of one layer does not overlap the overlap of another layer, relating to several embodiments. Objects can be 3D fabricated by repeatedly depositing powder layers and generating patterned layers from the powder layers. Powder layers can be deposited on a substrate or on a previously generated patterned layer. The powder layer 400 shown in Figure 4 may be a first powder layer. The first powder layer may be the initial powder layer or a subsequent powder layer. The segmented scanning pattern shown in Figure 4 can be an example of a first layer scanning pattern, which includes a first layer first section 401, a first layer second section 402, a first layer third section 403, a first layer first overlap 406, and a first layer second overlap 407. A first patterned layer can be generated by moving the molten pool along the first layer scanning pattern. A second patterned layer 507 can be generated directly on the first patterned layer 405. It can be seen that the second layer scanning pattern is orthogonal to the first layer scanning pattern. Furthermore, the second layer scanning pattern is not segmented because each scanning line in the second layer scanning pattern is shorter than the threshold. The threshold is the value that allows the molten pool to extend along the entire length of the scanning line, and also allows lateral heating to propagate to previously scanned lines, promoting the growth of the crystal structure from those scanning lines into the molten pool.

[0031] The third patterned layer 508 can be generated directly on the second patterned layer 507. The scanning pattern of the third layer is parallel to the scanning pattern of the first layer and orthogonal to the scanning pattern of the second layer. Experiments have shown that large crystals can be generated by rotating the scanning pattern from one layer to another, as shown in Figure 5. The scanning pattern of the third layer is a segmented scanning pattern having a first section, a second section, and a third section. Moving the molten pool along the first section of the third layer yields the first section 511 of the third patterned layer. In the example in Figure 5, moving the molten pool along the second section of the third layer yields the second section 510 of the third patterned layer. Moving the molten pool along the third section of the third layer yields the third section 509 of the third patterned layer. The first overlap of the third layer is where the first section and the second section of the third layer intersect. The third patterned layer's first overlap 513 is located where the molten pool passes through the third layer's first overlap. The third layer's second overlap is where the third layer's second section and the third layer's third section intersect. The third patterned layer's second overlap 512 is located where the molten pool passes through the third layer's second overlap.

[0032] As can be seen in Figure 5, the overlap of the third patterned layer does not overlap the overlap of the first patterned layer. More specifically, the first overlap 513 of the third patterned layer overlaps the first patterned layer 405, but does not overlap the first overlap 406 of the first patterned layer, nor the second overlap 407 of the first patterned layer. Furthermore, the second overlap 512 of the third patterned layer overlaps the first patterned layer 405, but does not overlap the first overlap 406 of the first patterned layer, nor the second overlap 407 of the first patterned layer. To promote the growth of large crystal structures throughout the layers, it is important that the overlap of one layer does not overlap the nearest lower layer (previous layer) or the overlaps of many previous layers. The previous layer may be any patterned layer below the top layer. Patterned sections that are not included in overlaps are more likely to have a higher quality crystal structure than patterned sections that are included in overlaps. Therefore, high-quality crystal structures are likely to grow from the lower layers to the uppermost overlapping layers.

[0033] Figure 6 is a high-level conceptual diagram showing a control system 601 for controlling a beam scanner and beam source in several embodiments. The control system may be a computer running software for controlling a 3D printer. The computer can send control signals to the beam scanner 101, beam source 102, and other components of the 3D printer while running the control system software. Those skilled in the art have many years of experience running control system software on a computer for controlling a 3D printer. The control system can store scan patterns 602. Scan patterns 602 may include a first layer scan pattern 603, a second layer scan pattern 611, a final layer scan pattern 612, and other layer scan patterns. Layer scan patterns may include sections. For example, the first layer scan pattern 603 is shown to include a first layer first section 604, a first layer second section 609, and a first layer final section 610, and may include many other first layer sections. Sections may include path data associated with scan speed and beam power. For example, the first layer, first section 604 is shown to contain a table in which each row contains an x-coordinate 605, a y-coordinate 606, a scanning speed value 607, and a beam power value 608. The control system 601 can read the row in the table and then command the beam scanner 101 and beam source 102 to set the energy beam to the beam power indicated by the beam power value 608 and to move the molten pool from its current position to the position indicated by the x-coordinate 605 and y-coordinate 606 at the scanning speed indicated by the scanning speed value 607.

[0034] Figure 7 is a high-level conceptual diagram showing a map 701 relating different scanning line lengths to different beam power or scanning speeds in several embodiments. The amount of energy delivered by the beam to the volume of material being patterned depends on the beam power and the time the beam is in contact with the volume of material. Here, the energy beam is scanned along the scanning pattern, thereby moving the molten pool. Therefore, the amount of energy delivered to the volume depends on the scanning speed and beam power. As discussed above, it is desirable that the molten pool extends completely across the entire scanning line or line segment, and that lateral heating melts the previous scanning line. It is also desirable that the molten pool extends slightly into the previous layer just below the top layer. The amount of energy delivered is limited because too much energy will simply melt the object being fabricated, or the molten volume will become too large, reducing the fabrication resolution. Therefore, the beam power 704, scanning speed 703, or both can be a function of the scanning length 702, where the scanning length is the length of the line segment within a section, or the length of the scanning line within a scanning pattern. For example, when patterning the second patterning layer 507 shown in Figure 5, the molten pool moves along the entire scanning line. When patterning the first patterning layer 405 and the third patterning layer shown in Figure 5, the molten pool moves along the scanning line segment. A map 701 of scanning length and scanning speed / scanning power may be used to determine the values ​​of the scanning pattern 602 shown in Figure 6. Alternatively, the map 701 may be used to set the beam power and scanning speed during the fabrication operation. In one example, if the first line segment of the line segment has a first length 705, which can be retrieved in the map 701 to determine a first beam power value 707 and a first scanning speed value 708, the energy beam generates the molten pool according to the map. In another example, the map does not contain length entries, and the first beam power value 707 and the first scanning speed value 708 are calculated by interpolation. The beam source can be set to a first beam power value 707 while the molten pool moves along the first line segment of the line segment.The scanning speed of the beam scanner can be set to a first scanning speed value 708 while the molten pool moves along the first line segment of the line segment. The second line segment of the line segment may have a second length 706. Because the first and second line segments of the line segment have different lengths, the beam power or scanning speed used for the second line segment of the line segment may not be equal to the beam power or scanning speed used for the first line segment of the line segment. If the first length 705 is not equal to the second length 706, the line segments have different lengths. Therefore, the second length 706 can be retrieved in or calculated from the map 701 (e.g., via interpolation) to determine the second beam power value 709 and the second scanning speed value 710. While the molten pool moves along the second line segment of the line segment, the beam source may be set to a second beam power value 709. The beam scanner's scanning speed may be set to a second scanning speed value of 710 while the molten pool moves along the second line segment of the line segment. In some implementations, a single scanning speed may be used and the beam power may be varied. In some implementations, a single beam power may be used and the scanning speed may be varied. In some implementations, both the scanning speed and beam power may be varied.

[0035] Figure 8 is a high-level conceptual diagram showing adaptive control of scanning speed or beam power to obtain a molten pool shape that is a desired molten pool shape, relating to several embodiments. The imager 809 can image the molten pool 104 and generate a molten pool image 806, which is an image of the molten pool. The imager 809 can be a video camera operating in the visible light range (visible to humans), a video camera operating in the infrared light range, etc. The molten pool image 806 can be a time-series molten pool image, for example, one image every 1 / 10th of a second, or one 1 / 30th of a second. The molten pool image 806 can be received by an image analyzer 804 that determines the molten pool shape 802. The molten pool comparator 803 can compare the molten pool shape 802 with the desired molten pool shape 801. For example, the desired molten pool shape can extend the entire length of the latest scanning line or scanning line segment, and the molten pool can extend partway (laterally) to the previous scanning line or scanning line segment. The difference between the observed molten pool shape and the desired molten pool shape may indicate that the beam power should be increased, decreased, the scanning speed should be increased, or the scanning speed should be decreased. The parameter adjuster 805 can generate a beam power adjustment 807 sent to the beam source 102, or a scanning speed adjustment 808 sent to the beam scanner 101. The beam power adjustment 807 and scanning speed adjustment 808 may cause the molten pool 104 to have the desired molten pool shape.

Claims

1. Steps include depositing a first powder layer, A step of generating a first patterned layer by moving a molten pool in the first powder layer along a first layer scanning pattern that includes a first section of the first layer, a second section of the first layer, and a first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect; The steps include depositing a second powder layer on the first patterned layer, A step of generating a second patterned layer by moving the molten pool in the second powder layer along the second layer scanning pattern, The steps include depositing a third powder layer on the aforementioned second patterned layer, A step of generating a third patterned layer by moving a molten pool in the third powder layer along a third layer scanning pattern that includes a third layer first section, a third layer second section, and a third layer first overlap where the third layer first section and the third layer second section intersect. Includes, The third layer first overlap overlaps the first section of the first layer or the second section of the first layer. The third layer first overlap does not overlap the first layer first overlap.

2. The first layer scanning pattern includes a plurality of first layer sections, and includes a plurality of first layer overlaps in which one of the first layer sections intersects with another of the first layer sections. The third layer scanning pattern includes a plurality of third layer sections, and includes a plurality of third layer overlaps in which one of the third layer sections intersects with another of the third layer sections. The third layer section overlaps the first layer section, The method according to claim 1, wherein none of the third layer overlaps overlap any of the first layer overlaps.

3. The method according to claim 1, wherein the growth of stray crystals in the first layer first overlap is suppressed by passing the molten pool through the first layer first overlap twice.

4. The first layer, first section includes a first scan line segment, The method according to claim 1, wherein the molten pool extends over the entire length of the first scanning line segment after the molten pool has been moved along the first scanning line segment.

5. The first section of the first layer includes a first scan line segment and a second scan line segment, The molten pool extends along the entire length of the first scanning line segment after the molten pool has moved along the first scanning line segment. The molten pool is moved along the second scanning line segment immediately after the molten pool has moved along the first scanning line segment. The method according to claim 1, wherein the molten pool does not extend over the entire length of the first scanning line segment after the molten pool has moved along the second scanning line segment.

6. The first section of the first layer includes a first scan line segment and a second scan line segment, The molten pool extends over the entire length of the first scanning line segment after the molten pool has moved along the first scanning line segment. The molten pool is moved along the second scanning line segment immediately after the molten pool has moved along the first scanning line segment. The molten pool, after it has moved along the second scanning line segment, does not extend over the entire length of the first scanning line segment. The method according to claim 1, wherein the molten pool extends from the second scanning line segment to the first scanning line segment by lateral heating.

7. The method according to claim 1, wherein multiple lengths of multiple scanning line segments are used to set the beam power of the energy beam that generates the melt pool.

8. The map associates multiple scan line lengths with multiple beam power values. The method according to claim 1, wherein multiple lengths of multiple scanning line segments are used to set the beam power of the energy beam that generates the melt pool according to the map.

9. The method according to claim 1, wherein the first scanning line segment and the second scanning line segment have different lengths, so the beam power when scanning the first scanning line segment is not equal to the beam power when scanning the second scanning line segment.

10. The first layer, first section includes a plurality of scan line segments having a plurality of lengths, The method according to claim 1, wherein the plurality of lengths of the plurality of scanning line segments are used to set the scanning speed of the energy beam that generates the molten pool.

11. The scanning speed has a first speed value when scanning the first scanning line segment among the plurality of scanning line segments. The scanning speed has a second speed value when scanning the second scanning line segment among the plurality of scanning line segments. The method according to claim 10, wherein the first scan line segment and the second scan line segment among the plurality of scan line segments have different lengths, and therefore the first speed value is not equal to the second speed value.

12. The map associates multiple scan line lengths with multiple scan speed values. The first layer, first section includes a plurality of scan line segments having a plurality of lengths, The method according to claim 1, wherein the plurality of lengths of the plurality of scanning line segments are used to set the scanning speed according to the map.

13. The energy beam is scanned, causing the molten pool to move. The energy beam has scanning speed and beam power, The series of molten pool images show the shape of the molten pool. The method according to claim 1, wherein the scanning speed or the beam power is adaptively controlled to obtain the molten pool shape which is a desired molten pool shape.

14. A powder supply device configured to generate a first powder layer and a second powder layer by depositing powder on a powder bed, A beam source configured to generate a molten pool in the aforementioned powder, A beam scanner configured to generate a first patterned layer and a second patterned layer by moving the molten pool relative to the powder bed, Equipped with, The first patterned layer is generated by moving the molten pool within the first powder layer along a first layer scanning pattern which includes a first section of the first layer, a second section of the first layer, and a first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. The second patterned layer is generated by moving the molten pool within the second powder layer along a second layer scanning pattern that includes a second layer first section, a second layer second section, and a second layer first overlap where the second layer first section and the second layer second section intersect. The first overlap of the second layer overlaps the first section of the first layer or the second section of the first layer. The system wherein the second layer first overlap does not overlap the first layer first overlap.

15. The system according to claim 14, wherein the growth of stray crystals is suppressed by passing the molten pool twice within the first layer first overlap.

16. The first layer includes a first scanning line segment and a second scanning line segment parallel to the first scanning line segment. The molten pool extends along the entire length of the first line segment after the molten pool has been moved along the first scanning line segment. The molten pool is moved along the second scanning line segment immediately after the molten pool has moved along the first scanning line segment. The molten pool, after it has moved along the second scanning line segment, does not extend along the entire length of the first line segment. The system according to claim 14, wherein the molten pool extends from the second scanning line segment to the first line segment by lateral heating.

17. The system according to claim 14, wherein multiple lengths of multiple scanning line segments are used to set the power of the beam source or the scanning speed of the molten pool.

18. A deposition means for depositing powder to generate multiple powder layers, Patterning means for generating multiple patterned layers by moving a molten pool within the aforementioned powder, Equipped with, The first patterned layer among the plurality of patterned layers is generated by moving the molten pool in the first powder layer among the plurality of powder layers along a first layer scanning pattern which includes a first section of the first layer, a second section of the first layer, and a first overlap of the first layer where the first section of the first layer and the second section of the first layer intersect. The second patterned layer among the plurality of patterned layers is generated by moving the molten pool within the second powder layer among the plurality of powder layers along the second layer scanning pattern. The third patterned layer among the plurality of patterned layers is generated by moving the molten pool in the third powder layer along a third layer scanning pattern that includes a third layer first section, a third layer second section, and a third layer first overlap where the third layer first section and the third layer second section intersect. The second patterned layer among the plurality of patterned layers is located above the first patterned layer among the plurality of patterned layers and below the third patterned layer among the plurality of patterned layers. The system wherein the third layer first overlap does not overlap the first layer first overlap.

19. The system according to claim 18, wherein the third layer first overlap overlaps the first section of the first layer or the second section of the first layer.

20. The system according to claim 18, wherein the growth of stray crystals is suppressed by passing the molten pool twice within the first layer first overlap.

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