English:
[0001] The present technology relates generally to the use of Direct Metal Laser Melting (DMLM), for use in the fabrication or repair of components, more particularly components of a gas turbine engine.
[0003] In making a build in current powder bed systems, a laser beam or electron beam is used to scan a layer of powder to sinter and melt the desired pattern in the layers of the powder bed. For some applications, the build can require days of processing time. One application of DMLM is in the fabrication and repair of airfoils for gas turbine engines for aircraft. The geometries of the airfoils are difficult to form using conventional casting technologies, thus fabrication of the airfoils using a DMLM process or an electron-beam melting process has been proposed. With the layers built upon one another and joined to one another cross-section by cross-section, an airfoil or portion thereof, such as for a repair, with the required geometries, may be produced. The airfoil may require post-processing to provide desired structural characteristics.
[0004] Three-dimensional metal part fabrication using the DMLM process generates extremely high temperature gradients and cooling rates that lead to internal part stress and cracking. This problem is particularly prevalent among nickel base superalloys, which retain high strength at high temperature, and are therefore of interest in airfoils. Crack-free part fabrication may be accomplished using heated build platforms, although custom inductive heaters are needed to reach the required temperatures. A second laser can be used in proximity to the melt pool and alter the cooling rate. However, current two-laser configurations require two independent sets of optics and scanners which are costly and challenging to coordinate.
[0005] In accordance with one example of the technology disclosed herein, a method of controlling the cooling rate of a melt pool of a powder bed comprises directing a first laser beam on the powder bed to form a melt pool; coaxially aligning a second laser beam with the first laser beam; and laterally offsetting a focus spot of the second laser beam with respect to the melt pool, wherein the second laser beam heats but does not melt powder within the focus spot.
[0006] In accordance with another example of the technology disclosed herein, a direct metal laser melting manufacturing system comprises at least one laser source to generate a first laser beam and a second laser beam; a reflector tiltable about two axes and configured to reflect the second laser beam; a beam combiner to pass the first laser beam and reflect the second laser beam reflected from the reflector; an optical system configured to coaxially align the first and second laser beams and direct the first and second laser beams to a powder bed, wherein the first laser beam forms a melt pool in the powder bed; a controller to tilt the reflector to laterally offset a focus spot of the second laser beam with respect to the melt pool, wherein the second laser beam heats but does not melt powder within the focus spot.
[0007] In accordance with still another example of the technology disclosed herein, a method of controlling a cooling rate of a melt pool of a powder bed comprises directing a laser beam on the powder bed to form a melt pool; and laterally oscillating the laser beam with respect to the melt pool to control a temperature of powder adjacent the melt pool
[0009] FIG. 1 schematically illustrates an in-line laser scanner to control cooling rates of direct metal laser melting additive manufacturing;
[0010] FIG. 2 schematically illustrates in-line laser scanning to control cooling rates of direct metal laser melting additive manufacturing;
[0011] FIG. 3 schematically illustrates a relationship between two laser spots or between two conditions of a single laser spot during direct metal laser melting manufacturing; and
[0012] FIG. 4 schematically illustrates a pattern that a single laser spot or multiple laser spots may follow during direct metal laser melting manufacturing.
[0013] Referring to FIG. 1, an inline scanner system 2 to control cooling rates of DMLM manufacturing processes comprises a first laser source 4 and a second laser source 6. The first laser source 4 provides a first laser beam 5 and the second laser source 6 provides a second laser beam 7. The first laser beam 5 may be referred to as a melt pool laser beam or the primary welding laser beam and the second laser beam 7 may be referred to as a heating laser beam. The inline scanner system 2 may further comprise a first lens 8 for the first laser beam 5 and a second lens 10 for the second laser beam 7. A two axes tip/tilt reflector, or mirror, 14 directs the second laser beam 7 to a beam combiner 16. The reflector, or mirror, 14 may be piezo-actuated. It should be appreciated that the reflector 14 may be a MEMS mirror (electrostatic) or acousto-optic (diffractive) element or an electro-optical deflector. It should be further appreciated that the reflector 14 may also be a galvo scanner (rotational motor) behind the beam combiner 16. The first laser beam 5 passes through the beam combiner 16 and the second laser beam 7 is reflected by the beam combiner 16.
[0014] The second laser beam 7 is coaxially aligned to the first laser beam 5 by reflecting off the tip/tilt reflector 14 and the beam combiner 16. The tip/tilt reflector 14 can alter a collimated beam path of the second laser beam 7 by a few tenths of a degree at several kHz (i.e. on the order of 0.1°). The beam combiner 16 may be a dichroic beam combiner and pass the first laser beam 5 while reflecting the second laser beam 7 for heating. Dichroic beam combiners are appropriate if the first and second laser sources 4, 6 are of differing wavelengths. A polarization-dependent beam combiner may be used if the first and second laser sources 4, 6 are of the same wavelength and have orthogonal polarizations. The two coaxial laser beams 5, 7 travel through a shared optical and scanner system 12 that focuses and directs the first laser spot 24 (from the first laser beam 5) and the second laser spot 26 (from the second laser beam 7) to a powder bed using first and second focal length lenses 18, 20 and a galvanometer scanning head 22.
[0015] Small tilt angles of the reflector 14 provide lateral offsets of the focus spot 26 with respect to the welding, or melt, pool 32 location in the powder bed 30 formed by the first laser spot 24, and a controlled cooling zone 36 that is formed by the second laser spot 26, as shown in FIG. 2. It should be appreciated that the controlled thermal zone 36 may follow or lead the melt pool 32 along the pattern 34. In the case of the controlled cooling zone 36 leading the melt pool 32, the second laser spot 26 is used to preheat the powder prior to melting. In the case of the controlled cooling zone 36 trailing the melt pool 32, the second laser spot 26 is used to control the solidification of the powder in the melt pool 32. In either case, the added heat leads to substantial reductions in the cooling rate of the weld pool both during and immediately after solidification.
[0016] Referring to FIG. 3, tilt angles as small as 0.1° can offset the secondary spot 26 by a distance D3 up to 1mm due to angular magnification through the long focal length lenses 18, 20 of the shared optical and scanner system 12. Coaxially combining both laser beams 5, 7 creates a local coordinate system centered on the weld pool 32. This eliminates having two coordinate systems which occurs when using two separate but registered scanning heads. The first laser spot 24 may have a first diameter Dl and the second laser spot 26 may have a second diameter D2. The second diameter D2 may be 1-lOx the first diameter Dl . The power and/or power density of the second laser spot 26 may also be different from the first laser spot 24.
[0017] The reflector 14 can be dynamically driven at several kHz, which is at least an an order of magnitude (i.e. at least lOx) faster than galvanometer scanners, though over a comparatively small range of motion. Fast tilt angle adjustments can be used to generate the scanned pattern 34 around the weld pool 32 to create a customized heating pattern in the controlled cooling zone 36 to alter the cooling rate. This pattern 34 may lead or follow the melt pool 32. High power lasers used for powder fusion can also be modulated at kHz rates adding the additional opportunity to dynamically change laser power in tandem with the heated area (e.g. pattern 34) around the melt pool 32.
[0018] Alternatively, a single laser may be used for both powder fusion and controlled cooling by dynamically tilting the reflector 14 and the galvanometer scanning head 22 in tandem. Laser output power can also be altered at kHz rates and can be tailored in conjunction with mirror tilt. The use of a single laser can be realized by eliminating the first laser, using only the second laser source 6 and reflecting the second laser beam 7 off the reflector 14 in a manner to achieve a controlled cooling zone. For example, the second laser beam 7 may be used to provide the laser spot 26 on the powder bed in a first direction to preheat the powder, and then the laser spot 26 could be moved by tilting the reflector 14 in second direction opposite to the first direction to form the melt pool in the preheated powder. As another example, the second laser spot 26 could be moved in a first direction to form a melt pool, and then the second laser spot could be moved in a second direction opposite to the first direction to control the cooling rate of the melt pool. It should be appreciated that the path of the laser spot 26 in the opposite direction need not be the exact opposite, i.e. a mirror image of the first direction. For example, as shown in FIG. 3, the pattern 34 may have a zigzag configuration and the laser spot 26 may move linearly in the first direction, and follow the pattern 34 in the second direction, or vice versa. It should also be appreciated that the pattern the laser spot 26, or the laser spots 24, 26, may be controlled to follow other patterns, such as a wobble pattern 38 as shown in FIG. 4. It should further be appreciated that the movements of the laser spot must occur at very high rates, essentially oscillating around or about the melt pool.
[0019] A controller 28 may control each laser source 4, 6 and each laser beam 5, 7. The controller 28 may also control the reflector 14 and the shared optical and scanner system 12. The controller may control the power, profile, and duration of the first and second laser beams 5, 7, and the rate at which the power of each laser source 4, 6, is reduced when turned off. For a given layer of powder, for example above an airfoil to be repaired, the laser sources 4, 6 are activated to melt the powder in the desired shape per a CAD design, which may be input and/or stored in the controller 28. This process may be repeated as many times as necessary to build up the required region. In the case of the system being used to fabricate a component, e.g. an airfoil, the process is repeated as many times as necessary to build the component. The controller 28 may also control an actuator to move a support of the powder bed 30 downwardly as layers of powder are added and subsequently processed by the laser beams 5, 7. Each layer formed may be, for example, about 1 μιη to about 1 mm thick. In the case of repair of an airfoil, each layer may be formed, for example, about 10 - 100 μιη thick.
[0020] The controller 28 may be a computer processor or other logic-based device, software components (e.g., software applications), and/or a combination of hardware components and software components (e.g., a computer processor or other logic-based device and associated software application, a computer processor, or other logic-based device having hard-wired control instructions, or the like).
[0021] The reflector 14 may be controlled by the controller 28 to control the temperature of powder near or adjacent to the melt pool 32 to alter the cooling rate of the melted powder. The controller 28 may also control the second laser source 6 and the second laser beam 7, along with the reflector 14, to preheat the powder bed 30 and/or the component to be repaired. The pre-heating power densities of the second laser beam 7 may be from about 10- 100,000 watts/cm2. By pre-heating the powder bed 30 and/or the component and/or heating the region near or adjacent to the melt region, the thermal gradient may be controlled to be substantially only in the direction normal to the powder bed. This will reduce cracking in materials that are sensitive to fast solidification cooling rates. Desirable grain growth that is normal to the layer surface may be achievable with planar cooling of a powder bed layer. This allows formation of a directionally solidified (DS) type grain structure or a single crystal structure with the build repair of an airfoil type structure. It should also be appreciated that the first laser source 4 and the first laser beam 5 may be controlled to heat the powder bed 30 to control the temperature and temperature gradient of the melt pool 32. Controlling the temperature and the temperature gradient of the melted region allows control over, for example, evaporation of the powder, the grain structure of the solidified layer, and/or the surface finish of the repair or component. Spatial control of the cooling rates in the 2D plane of each build layer allows the grain structure of each build layer to be controlled, as well as the grain structure in 35 as the build layers are added to form the build. Spatial control of the cooling rates in the 2D plane of each build layer also enables special treatments of the volumes that will form the surfaces of the 3D build or part. This allows control of the surface roughness and density (porosity) at the surface, which may improve mechanical properties of the part, for example fatigue.
[0022] The material in the powder bed 30 may be metal powder, for example, a nickel or cobalt or iron based superalloy. For example, the powder may be CoCrMo powder. The diameter of the particles of the powder bed may be from, for example, 10-100 μπι, for example from 40-60μιη. It should be appreciated that other materials, for example plastic, ceramic, or glass, may be used for the powder bed. Depending on the material in the powder bed, the power of the welding laser beam 5 may be from about 100 to about 1000 watts.
[0023] Slowed cooling rates lead to reduced stress within parts fabricated using DMLM. Coaxially aligning the second laser beam 7 with the tip/tilt reflector 14 enables the second spot 26 to be projected around the melt pool 32 using the same set of scanning optics 12. As piezo-mirrors are greater than lOx faster than galvo scanners, custom heat patterns may be applied near the weld pool 32 which would not be possible using a second independent laser source due the inherently slower response of galvanometers.
[0024] The reflector 14 may be tilted by less than 0.25° to laterally offset the cooling spot 26 and can operate more than lOx faster than a galvo scan head. The high speed of the piezo- mirror may enable a single laser to be used for both powder fusion and controlled cooling. This configuration reduces component cost and provides new opportunities to generate a unique, local cooling pattern 34 around the melt pool 32. The technology can be implemented through commercial-off-the-shelf parts and adapted to various DMLM machines.
[0025] Controlled cooling rates enable crack-free parts in alloys that cannot be conventionally processed via DMLM, and have been proven by Applicants through platform heating. The technology disclosed herein is applicable to any commercial DMLM system and may reduce part stress, cracking, and distortion with minimal added system cost beyond a second laser source. Time between powder recoat can be reduced since the second laser is controlling cooling rate instead of depending on platform heaters to reach thermal equilibrium.
[0027] It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular example. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
[0028] While only certain features of the present technology have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes.

中文:
[0001]本技术大体涉及直接金属激光熔化(DMLM)的使用,用于在制造或修理部件(更特别地,燃气涡轮发动机的部件)中使用。
[0003]在现有的粉末床系统中进行构建时,激光束或电子束被用以扫描一层粉末以在粉末床的层中烧结并且熔化所需图案。对于一些应用,构建可能要求数天的处理时间。DMLM的一个应用是用于飞行器的燃气涡轮发动机的翼型件的制造和修理。使用常规的铸造技术难以形成翼型件的几何形状,因而已提出使用DMLM处理或电子束熔化处理来制造翼型件。随着层被构建在彼此之上并且横截面和横截面彼此连结,可以产生带有所要求的几何形状的翼型件或其部分,诸如用于修理。翼型件可能要求后处理以提供所需结构特性。
[0004]使用DMLM处理的三维金属部件制造产生极高的温度梯度和冷却速率,其导致内部部件应力和开裂。该问题在镍基超合金之中特别普遍,镍基超合金在高温下保持高强度,因此在翼型件中受到关注。尽管需要定制的感应加热器来达到所要求的温度,但是,可以使用被加热的构建平台来完成无开裂部件制造。可以接近于熔化池使用第二激光并更改冷却速率。然而,现有的双激光构造要求独立的两套光学器件和扫描器,其昂贵且难以协调。
[0005]根据文中公开的技术的一个示例,一种控制粉末床的熔化池的冷却速率的方法包含:在粉末床上引导第一激光束以形成熔化池;使第二激光束与第一激光束同轴地对准;以及,使第二激光束的聚焦光斑相对于熔化池横向偏移,其中,第二激光束加热但不熔化聚焦光斑内的粉末。
[0006]根据文中公开的技术的另一示例,一种直接金属激光熔化制造系统包含:至少一个激光源,其产生第一激光束和第二激光束;反射器,其能够绕着两个轴线倾斜并且被构造成反射第二激光束;束组合器,其使第一激光束通过并且反射从反射器反射的第二激光束;光学系统,其被构造成使第一激光束和第二激光束同轴地对准并且将第一激光束和第二激光束引导至粉末床,其中,第一激光束在粉末床中形成熔化池;控制器,其使反射器倾斜以使第二激光束的聚焦光斑相对于熔化池横向偏移,其中,第二激光束加热但不熔化聚焦光斑内的粉末。
[0007]根据文中公开的技术的又一示例,一种控制粉末床的熔化池的冷却速率的方法包含:在粉末床上引导激光束以形成熔化池;以及,使激光束相对于熔化池横向振荡,以控制邻近熔化池的粉末的温度。
[0009]图1示意性地图示控制直接金属激光熔化增材制造的冷却速率的在线(in-line)激光扫描器;
[0010]图2示意性地图示控制直接金属激光熔化增材制造的冷却速率的在线激光扫描;
[0011]图3示意性地图示在直接金属激光熔化制造期间两个激光光斑之间或单个激光光斑的两个状态之间的关系;以及
[0012]图4示意性地图示在直接金属激光熔化制造期间单个激光光斑或多个激光光斑可以跟随的图案。
[0013]参考图1,控制DMLM制造处理的冷却速率的在线扫描器系统2包含第一激光源4和第二激光源6。第一激光源4提供第一激光束5,第二激光源6提供第二激光束7。第一激光束5可以称为熔化池激光束或主要焊接激光束,第二激光束7可以称为加热激光束。在线扫描器系统2可以进一步包含用于第一激光束5的第一透镜8和用于第二激光束7的第二透镜10。两轴偏斜/倾斜反射器或反射镜14将第二激光束7引导到束组合器16。反射器或反射镜14可以是压电致动的。应当理解,反射器14可以是MEMS反射镜(静电)或声光(衍射)元件或电光偏转器。应当进一步理解,反射器14也可以是束组合器16后面的振镜扫描器(旋转马达)。第一激光束5穿过束组合器16,第二激光束7被束组合器16反射。
[0014]通过反射偏离偏斜/倾斜反射器14和束组合器16,第二激光束7与第一激光束5同轴地对准。偏斜/倾斜反射器14可以在数kHz下将第二激光束7的准直束路径更改十分之几度(即,在0.1°的量级)。束组合器16可以是二向色束组合器,并且在反射第二激光束7用于加热时,使第一激光束5通过。如果第一激光源4和第二激光源6是不同的波长,则二向色束组合器是适当的。如果第一激光源4和第二激光源6是相同的波长并具有正交偏振,则可以使用偏振相关的束组合器。两个同轴激光束5,7行进通过共享光学和扫描器系统12,使用第一焦距透镜18、第二焦距透镜20和检流计扫描头22,共享光学和扫描器系统12使第一激光光斑24(来自第一激光束5)和第二激光光斑26(来自第二激光束7)聚焦并且引导至粉末床。
[0015]反射器14的小倾斜角度提供聚焦光斑26相对于通过第一激光光斑24形成的在粉末床30中的焊接或熔化池32位置以及通过第二激光光斑26形成的受控冷却区36的横向偏移,如图2所示。应当理解,受控热区36可以沿着图案34跟随或引导熔化池32。在受控冷却区36引导熔化池32的情况下,第二激光光斑26被用以在熔化之前预加热粉末。在受控冷却区36尾随熔化池32的情况下,第二激光光斑26被用以控制熔化池32中粉末的固化。在任一情况下,增添的热量导致在固化期间以及紧接在固化之后焊接池的冷却速率皆实质减小。
[0016]参考图3,由于经过共享光学和扫描器系统12的长焦距透镜18,20的角度放大,小到0.1°的倾斜角度可以使二级光斑26偏移多达1mm的距离D3。同轴地组合两个激光束5、7生成以焊接池32为中心的局部坐标系。这消除了当使用两个分离但校准的扫描头时发生的具有两个坐标系的情况。第一激光光斑24可以具有第一直径D1,第二激光光斑26可以具有第二直径D2。第二直径D2可以是第一直径D1的1-10倍。第二激光光斑26的功率和/或功率密度还可以与第一激光光斑24不同。
[0017]反射器14可以在数kHz下被动态地驱动,其比检流计扫描器快至少一个数量级(即,至少10倍),虽然在相比较小的运动范围内。快速倾斜角度调节可以被用以围绕焊接池32产生扫描图案34,以在受控冷却区36中生成定制的加热图案,以更改冷却速率。该图案34可以引导或跟随熔化池32。用于粉末熔融的高功率激光也可以以kHz速率调制,增添了与围绕熔化池32的受热区块(如,图案34)配合地动态改变激光功率的额外机会。
[0018]替换性地,通过配合地动态倾斜反射器14和检流计扫描头22,单个激光可以被用于粉末熔融和受控冷却两者。激光输出功率也可以以kHz速率更改,并且可以连同反射镜倾斜一起调整。通过消除第一激光、仅使用第二激光源6并且以获得受控冷却区的方式使第二激光束7反射偏离反射器14,可以实现单个激光的使用。例如,第二激光束7可以被用以在第一方向上在粉末床上提供激光光斑26以预加热粉末,然后可以通过使反射器14沿与第一方向相反的第二方向倾斜来移动激光光斑26,以在预加热粉末中形成熔化池。作为另一示例,第二激光光斑26可以在第一方向上移动以形成熔化池,然后第二激光光斑可以在与第一方向相反的第二方向上移动,以控制熔化池的冷却速率。应当理解,激光光斑26在相反方向上的路径不需要是准确相反的,即,第一方向的镜像。例如,如图3所示,图案34可以具有Z字形构造,并且激光光斑26可以在第一方向上沿直线移动,并且在第二方向上跟随图案34,反之亦然。还应当理解,可以控制激光光斑26或激光光斑24,26的图案以跟随其他图案,诸如如图4所示的摇摆图案38。应当进一步理解,激光光斑的移动必须以非常高的速率发生,基本上围绕或绕着熔化池振荡。
[0019]控制器28可以控制每个激光源4、6和每个激光束5、7。控制器28还可以控制反射器14和共享光学和扫描器系统12。控制器可以控制第一激光束5和第二激光束7的功率、轮廓和持续时间,以及当关闭时每个激光源4、6的功率减少的速率。对粉末(例如,在待修理的翼型件上面)的给定层,激活激光源4、6以按照CAD设计使粉末熔化成所需形状,CAD设计可以被输入和/或存储在控制器28中。只要必要,该处理可以重复许多次以构建起所要求的区域。在系统被用以制备部件(如,翼型件)的情况下,该处理可以根据需要重复许多次以构建部件。控制器28还可以控制致动器以在粉末层被增添并随后通过激光束5、7处理时向下移动粉末床30的支撑件。所形成的每一层例如可以是大约1μm到大约1mm厚。在修理翼型件的情况下,每一层例如可以形成为大约10-100μm厚。
[0020]控制器28可以是计算机处理器或其他基于逻辑的设备,软件部件(如,软件应用),与/或,硬件部件和软件部件的组合(如,计算机处理器或其他基于逻辑的设备及关联软件应用,计算机处理器,或,具有硬布线控制指令的其他基于逻辑的设备,等等)。
[0021]反射器14可以通过控制器28控制,以控制靠近或邻近于熔化池32的粉末的温度,以更改熔化粉末的冷却速率。控制器28还可以控制第二激光源6和第二激光束7,以及反射器14,以预加热粉末床30和/或待修理的部件。第二激光束7的预加热功率密度可以选自大约10-100,000瓦/cm2。通过预加热粉末床30和/或部件与/或加热靠近或邻近于熔化区域的区域,可以将热梯度控制为实质上仅在与粉末床垂直的方向上。这将减少对快速固化冷却速率敏感的材料中的开裂。随着粉末床层的平面冷却,可以能够获得与层表面垂直的理想晶粒生长。这允许形成具有翼型件型结构的构建修理的定向固化(DS)型晶粒结构或单晶结构。还应当理解,可以控制第一激光源4和第一激光束5来加热粉末床30,以控制熔化池32的温度和温度梯度。控制熔化区域的温度和温度梯度例如允许对粉末蒸发、固化层的晶粒结构与/或修理或部件的表面抛光的控制。每一构建层的2D平面中的冷却速率的空间控制允许控制每一构建层的晶粒结构,以及在构建层被增添以形成构建时35中的晶粒结构。每一构建层的2D平面中的冷却速率的空间控制还使得能够对将形成3D构建或部件的表面的容积进行特殊处理。这允许对在表面处的表面粗糙度和密度(孔隙率)的控制,这可以改善部件的机械性能,例如疲劳。
[0022]粉末床30中的材料可以是金属粉末,例如,镍或钴或铁基超合金。例如,粉末可以是CoCrMo粉末。粉末床的颗粒的直径例如可以选自10-100μm,例如,选自40-60μm。应当理解,其他材料,例如塑料、陶瓷或玻璃可以被用于粉末床。依托于粉末床中的材料,焊接激光束5的功率可以选自大约100到大约1000瓦。
[0023]冷却速率减慢导致使用DMLM制造的部件内的应力减小。第二激光束7与偏斜/倾斜反射器14同轴地对准使第二光斑26能够使用同一套扫描光学器件12围绕熔化池32而被投射。因为压电镜比振镜扫描器快10倍以上,所以,可以靠近焊接池32应用定制的加热图案,而这由于检流计固有的较慢响应,使用第二独立激光源是不可能的。
[0024]反射器14可以倾斜少于0.25°,以使冷却光斑26横向偏移并且可以比振镜扫描头快10倍以上地操作。压电镜的高速度可以使单个激光能够被使用于粉末熔融和受控冷却两者。该构造减少部件成本并且提供围绕熔化池32产生独特的局部冷却图案34的新机会。该技术可以经过商用现成品部件来实施,并适配于各种DMLM机器。
[0025]受控冷却速率使合金中的无开裂部件成为可能,并且已被申请人经过平台加热证实,无开裂部件不可以经由DMLM常规处理。文中公开的技术适用于任何商用DMLM系统,并且可以以超出第二激光源的最小的添加系统成本减少部件应力、开裂和变形。由于第二激光控制冷却速率而非依托于平台加热器来达到热平衡,所以,可以减少粉末重涂布之间的时间。
[0027]应要了解,根据任何特定示例,可以不必获得上述所有这些目的或优点。因而,例如,本领域技术人员将认识到,文中描述的系统和技术可以以获得或优化如文中所教导的一个优点或一组优点的方式具体化或实行,而不必获得如文中可以教导或表明的其他目的或优点。
[0028]虽然文中仅图示和描述了本技术的某些特征,但是,本领域技术人员将容易想到许多修改和改变。因此,应要理解,所附权利要求旨在涵盖所有这些修改和改变。