Cleaning apparatus and cleaning method

Abstract

To provide a washing device and a washing method which suitably removes unnecessary powder from a metal lamination shaped body.SOLUTION: A washing device 10 washes a metal lamination shaped body 20 which is formed by laminating layers formed by laying a metallic powder material all over as the layers melted / bound or sintered by partly applying laser beams. The washing device 10 includes an inside container 12 which is filled with a mixed solvent M as liquid formed by mixing a plurality of organic solvents and stores the metal lamination formed body 20 immersed in the mixed solvent M, and an ultrasonic wave generator 13 which transmits ultrasonic waves U to the metal lamination formed body 20 stored in the inside container 12. The plurality of organic solvents includes a first organic solvent having a vapor pressure higher than that of other organic solvents and a second organic solvent having a higher acoustic impedance higher than that of other organic solvents.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a cleaning device and a cleaning method.

Background Art

[0002] Various methods for manufacturing three-dimensional objects made of metal with complex shapes have been developed. As an example, a powder bed fusion method is known (for example, Patent Document 1). The powder bed fusion method involves spreading a metal powder material flat to form a thin layer, and irradiating a laser beam onto the area of the thin layer that is desired to be hardened to sinter or melt-bond the powder material to produce a metal laminated object, and then cleaning the produced metal laminated object to remove unnecessary powder materials (such as unhardened powder materials) from the metal laminated object to produce a three-dimensional object. Patent Document 1 describes that by emitting ultrasonic waves to a part immersed in a cleaning liquid, the powder adhering to the part can be peeled off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In addition to the method described in Patent Document 1, other methods for removing metal material from metal additive manufactured bodies include manual removal using tools such as spoons and air blowers, and removal using solvents or abrasives for powder removal. When manufacturing complex three-dimensional objects using powder bed fusion, it is necessary to remove metal powder from confined spaces. However, it is difficult to insert tools into these confined spaces. Therefore, when manufacturing complex three-dimensional objects using powder bed fusion, methods using tools may not be able to sufficiently remove unwanted metal powder. Furthermore, when removing metal powder from a closed-end channel-like section, it is difficult to apply pressure to flow solvents or abrasives into that section. Therefore, in such cases, methods using solvents or abrasives may not be able to sufficiently remove unwanted metal powder.

[0005] Furthermore, when creating three-dimensional objects using metals with low melting points and low laser absorption efficiency, such as copper and copper alloys, the laser light is scattered to areas outside the irradiated region. In such cases, the scattered light heats the entire object, raising its temperature and potentially causing sintering, which can lead to the powder particles bonding together. If the powder particles bond together, it becomes difficult to remove the unwanted powder from the metal additively manufactured object. Since Patent Document 1 does not examine the cleaning solution into which the metal additively manufactured object is immersed, there was a possibility that the method described in Patent Document 1 could not adequately remove the unwanted sintered metal powder.

[0006] This disclosure has been made in view of these circumstances and aims to provide a cleaning apparatus and a cleaning method that can suitably remove unwanted powder from a metal additively manufactured body. [Means for solving the problem]

[0007] To solve the above problems, the cleaning apparatus and cleaning method of this disclosure employ the following means. A cleaning apparatus according to one aspect of the present disclosure is a cleaning apparatus for cleaning a metal additive manufactured body formed by laminating layers of metal powder material, some of which are melt-bonded or sintered by irradiation with laser light, the apparatus comprising: a housing section filled with a mixed solvent which is a liquid mixture of a plurality of organic solvents, for housing the metal additive manufactured body immersed in the mixed solvent; and an ultrasonic transmitting section for transmitting ultrasonic waves to the metal additive manufactured body housed in the housing section, wherein the plurality of organic solvents include a first organic solvent having a higher vapor pressure than the other organic solvents, and a second organic solvent having a higher acoustic impedance than the other organic solvents.

[0008] Furthermore, a cleaning method according to one aspect of the present disclosure is a cleaning method for a metal additive manufactured body formed by laminating layers of metal powder material, some of which are melt-bonded or sintered by irradiation with laser light, comprising: a storage step of storing the metal additive manufactured body in a state immersed in a storage unit filled with a mixed solvent which is a liquid obtained by mixing a plurality of organic solvents; and an ultrasonic transmission step of transmitting ultrasonic waves from an ultrasonic transmitting unit to the metal additive manufactured body storing in the storage unit, wherein the plurality of organic solvents include a first organic solvent having a higher vapor pressure than the other organic solvents and a second organic solvent having a higher acoustic impedance than the other organic solvents. [Effects of the Invention]

[0009] According to this disclosure, unwanted powder can be suitably removed from a metal additively manufactured body. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic longitudinal cross-sectional view of a cleaning apparatus according to an embodiment of the present disclosure. [Figure 2] This is a flowchart showing a cleaning method according to an embodiment of the present disclosure. [Figure 3] This diagram illustrates the principle of powder removal by cavitation. [Modes for carrying out the invention]

[0011] An embodiment of the cleaning apparatus and cleaning method relating to this disclosure will be described below with reference to the drawings. The cleaning apparatus 10 according to this embodiment is used when manufacturing three-dimensional objects made of metal. The metal used as the material is not particularly limited. For example, it may be a metal with a low melting point and low laser absorption rate (e.g., copper or copper alloy), or it may be a metal with a high melting point and high laser absorption rate (e.g., nickel alloy). When manufacturing a three-dimensional object, a metal additive body 20 is first created by stacking layers of metal powder material, some of which are melted or sintered by irradiating them with laser light. Then, the three-dimensional object is manufactured by removing unnecessary powder material from this metal additive body 20. The cleaning device 10 according to this embodiment is used when removing unnecessary powder material from the metal additive body 20. The metal additive manufactured body 20 of this embodiment has a plurality of bottomed holes 21 formed therein. The holes 21 are formed so as to be recessed from the surface of the metal additive manufactured body 20.

[0012] As shown in Figure 1, the cleaning device 10 comprises an outer container 11 forming the outer shell, an inner container (housing section) 12 provided inside the outer container 11, and an ultrasonic generator (ultrasonic transmitting section) 13 provided inside the outer container 11 and below the inner container 12.

[0013] The outer container 11 has a cylindrical outer container body portion 11a and an outer container bottom portion 11b that closes the lower end of the outer container body portion 11a. The upper end of the outer container body portion 11a is open. The inside of the outer container 11 is filled with liquid (in this embodiment, water W as an example). The substance that is filled inside the outer container 11 can be any substance that does not easily attenuate ultrasonic waves, and is not limited to water. The water level W filled inside the outer container 11 is higher than the upper end of the inner container body 12a, which will be described later.

[0014] The internal space of the outer container 11 is divided vertically by a porous plate 14 extending in the horizontal direction. The outer peripheral portion of the porous plate 14 is fixed to the inner peripheral surface of the outer container 11. A plurality of holes penetrating in the vertical direction are formed in the porous plate 14. The material of the porous plate 14 is not particularly limited, but it is preferably formed of a material (for example, stainless steel) that does not significantly attenuate the ultrasonic wave U from the ultrasonic generator 13.

[0015] The inner container 12 integrally has a cylindrical inner container main body portion 12a and an inner container bottom surface portion 12b that closes the lower end of the inner container main body portion 12a. The upper end of the inner container main body portion 12a is closed from above by a lid portion 12c. The inner container 12 is placed on the upper surface of the porous plate 14. The inner container 12 is substantially entirely immersed in the water W filled in the outer container 11. Specifically, the inner container 12 is immersed in the water W filled in the outer container 11 except for a part of the upper side of the lid portion 12c.

[0016] Inside the inner container 12, a liquid mixed solvent M in which a plurality (in this embodiment, three types as an example) of organic solvents are mixed is filled. Further, a metal laminated structure body 20 is accommodated inside the inner container 12. Therefore, inside the inner container 12, the metal laminated structure body 20 in a state of being immersed in the mixed solvent M is accommodated. Details of the mixed solvent will be described later. Media M will be described later.

[0017] A supply pipe (not shown) for supplying the mixed solvent M is connected to the inner container 12. The supply pipe may be provided, for example, to penetrate the lid portion 12c. The material of the inner container 12 is not particularly limited, but it is preferably formed of a material (for example, stainless steel) that does not significantly attenuate the ultrasonic wave U from the ultrasonic generator 13.

[0018] Next, the mixed solvent M will be described. The mixed solvent M is a mixture of three types of organic solvents: a first organic solvent, a second organic solvent, and a third organic solvent. Mixing the three types of organic solvents is for the purpose of improving the generation frequency and intensity of cavitation, as will be described later. When the characteristics of both the vapor pressure and acoustic impedance of each organic solvent contained in the mixed solvent M satisfy the required conditions, the generation frequency and intensity of cavitation are improved.

[0019] The first organic solvent has a higher vapor pressure than the other organic solvents (in this embodiment, the second organic solvent and the third organic solvent) contained in the mixed solvent M. The first organic solvent is preferably, for example, an organic solvent having a vapor pressure of 2.5 kPa or more at room temperature. The first organic solvent may be, for example, acetone. The ease of evaporation (high vapor pressure) of the solvent has a great influence on the generation frequency of cavitation.

[0020] The second organic solvent has a higher acoustic impedance (speed of sound × density) than the other organic solvents (in this embodiment, the first organic solvent and the third organic solvent) contained in the mixed solvent M. The second organic solvent is preferably, for example, an organic solvent having an acoustic impedance of 700 kPa·s / m 3 or more at room temperature. The second organic solvent may be, for example, methyl ethyl ketone, isopropyl alcohol, or ethanol. Acoustic impedance has a great influence on the generation intensity of cavitation.

[0021] The third organic solvent has a lower viscosity than the other organic solvents (in this embodiment, the first organic solvent and the second organic solvent) contained in the mixed solvent M. The third organic solvent is preferably, for example, an organic solvent having a viscosity of 1.0 mPas or less at room temperature. The third organic solvent may be, for example, n-hexane, n-pentane, or ether. Viscosity has a great influence on the generation intensity of cavitation.

[0022] The mixing ratio of each organic solvent may be determined in consideration of both the cavitation intensity and the generation frequency according to the powder material to be removed.

[0023] The ultrasonic generator 13 is positioned below the perforated plate 14. The ultrasonic generator 13 is located on the upper surface of the bottom surface 11b of the outer container. The ultrasonic generator 13 transmits ultrasonic waves U upward. The ultrasonic generator 13 transmits ultrasonic waves U to the metal additive body 20 via the water W inside the outer container 11 and the mixed solvent M inside the inner container 12.

[0024] The frequency of the ultrasonic waves U transmitted by the ultrasonic generator 13 is set to a frequency range of tens to hundreds of kHz in which cavitation occurs. Within this range, the smaller the frequency of the ultrasonic waves U, the less the amplitude decreases, and the easier it is for cavitation to occur overall. Therefore, by setting the frequency of the ultrasonic waves U within this range, cavitation can be suitably generated and powder can be removed.

[0025] Furthermore, the cleaning device 10 is equipped with a control device that controls various devices (for example, an ultrasonic generator, etc.). The controller includes, for example, a CPU (Central Processing Unit: processor), main memory, secondary storage (memory), etc. Furthermore, the controller may also include a communication unit for sending and receiving information with other devices. Main memory consists of writable memory such as cache memory and RAM (Random Access Memory), and is used as a work area for reading CPU executable programs and writing processing data by executable programs. Secondary storage devices are non-transitory computer-readable storage media. Examples of secondary storage devices include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory. A series of processes for realizing various functions are stored in secondary memory in the form of a program, for example. The CPU reads this program into main memory and performs information processing and calculations to realize the various functions. The program may be pre-installed in secondary memory, provided stored on a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory.

[0026] Next, the cleaning method for the metal additive manufacturing body 20 will be explained using the flowchart in Figure 2. As shown in Figure 1, the cleaning method according to this embodiment first vibrates the metal additive manufactured body 20 using a dry vibrator (not shown) to remove unwanted powder material from the metal additive manufactured body 20 (step S1). The dry vibrator vibrates the metal additive manufactured body 20 without immersing it in a liquid or the like. In this step, it is difficult to remove unwanted powder material in the sintered state as described above. However, by providing a dry vibrator step before ultrasonic cleaning, which will be described later, it is possible to facilitate the penetration of the mixed solvent M during ultrasonic cleaning.

[0027] Next, the metal additive manufactured body 20 is placed in a predetermined position in the inner container 12 and immersed in the mixed solvent M (placement step; step S2). Next, ultrasonic waves U are transmitted from the ultrasonic generator 13 (ultrasonic transmission step) to ultrasonically clean the metal additive manufactured body 20 (step S3). By transmitting ultrasonic waves U from the ultrasonic generator 13, cavitation is generated in the mixed solvent M. As a result of cavitation, the sintered powder material is crushed, so unwanted powder material can be removed from the metal additive manufactured body 20. Details of the principle of powder removal by cavitation will be described later. After ultrasonic cleaning is complete, it is then determined whether the unwanted powder material has been sufficiently removed from the metal additive manufacturing body 20 (step S4). If it is determined that the removal of the unwanted powder material is complete, the cleaning of the metal additive manufacturing body 20 is terminated.

[0028] If it is determined in step S4 that the removal of unwanted powder material has not been completed, the next step is to determine whether the amount of mixed solvent M in the inner container 12 is sufficient (step S5). Whether the amount of mixed solvent M is sufficient can be determined, for example, by whether a part of the metal additive manufactured body 20 is exposed from the mixed solvent M. In this case, if even a part of the metal additive manufactured body 20 is exposed from the mixed solvent M, it is determined that the amount of mixed solvent M is insufficient.

[0029] If it is determined in step S5 that the amount of mixed solvent M in the inner container 12 is sufficient, the process returns to step S3 and ultrasonic cleaning is performed again. On the other hand, if it is determined in step S5 that the amount of mixed solvent M in the inner container 12 is insufficient, the mixed solvent M is added to the inner container 12 via the supply piping (not shown) (step S6). Then, the process returns to step S3 and ultrasonic cleaning is performed again.

[0030] In this embodiment, the metal additive manufactured body 20 is cleaned in this manner. After cleaning the metal additive manufactured body 20 using the cleaning method of this embodiment, fine cracks characteristic of ultrasonic waves (cracks with a depth of about 10 μm and a width of about 5 μm) have formed on the surface. Since these cracks are very small, they do not affect the quality of the manufactured three-dimensional object. If it is determined in step S4 that sufficient excess powder material has been removed from the metal additive manufacturing body 20, the metal additive manufacturing body 20 may be removed from the cleaning device 10 and vibrated again with a dry vibrator (not shown). Since the sintered powder material is crushed in step S4, vibrating the metal additive manufacturing body 20 with a dry vibrator after step S4 can remove the crushed powder material from the metal additive manufacturing body 20.

[0031] Next, the principle of powder removal by cavitation will be explained using Figure 3. In Figure 3, the symbol P indicates the powder material remaining in the hole 21 of the metal additive body 20 after the powder materials have been sintered together. The symbol B indicates bubbles generated in the mixed solvent M by ultrasonic waves U. Furthermore, (a) shows a magnified view of the area enclosed by the dashed line.

[0032] As shown in Figure 3(a), when ultrasonic waves U (see Figure 1) are irradiated onto the gas molecules of the mixed solvent M, the gas pressure falls below the vapor pressure due to positive and negative pressure cycles, causing evaporation and the generation of bubbles B, which then foam. In other words, as shown in Figure 3(a), a pressure non-uniformity occurs between the internal pressure P1 and the external pressure P2 of bubble B.

[0033] Bubble B is released foam As a result, as shown in Figure 3(b), a high-pressure, high-speed flow of the mixed solvent M is generated, and this flow collides with the sintered powder material P (see arrow A). This causes the sintered powder material P to break down, making it removable. Figure 3(c) shows the state after a portion of the sintered powder material P has been removed.

[0034] In this way, the repeated generation and foaming of bubbles B makes it possible to remove the sintered powder material P.

[0035] According to this embodiment, the following effects and advantages are achieved. In this embodiment, ultrasonic waves U are transmitted to the metal additive manufactured body 20 while it is immersed in a mixed solvent M. This allows, for example, the metal additive manufactured body 20 to detect narrowed areas. The place Even in this case, the mixed solvent M flows into the confined area. Therefore, the powder material P remaining in the confined area can be removed by the flowing mixed solvent M. Furthermore, in this embodiment, cavitation is generated in the mixed solvent M by ultrasonic waves U. When bubbles are generated in the mixed solvent M, the high-pressure, high-speed flow of the mixed solvent M collides with the sintered powder material P, thereby crushing the sintered powder material P. This makes it possible to remove the sintered powder material P. Thus, in this embodiment, unwanted powder can be suitably removed from the metal additively manufactured body 20.

[0036] Furthermore, the frequency of cavitation is primarily influenced by the ease of evaporation of the solvent (high vapor pressure). In this embodiment, a first organic solvent with high vapor pressure is included among the multiple organic solvents. This improves the frequency of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent M, and the sintered powder material P can be more effectively removed.

[0037] Furthermore, the intensity of cavitation is dominated by the acoustic impedance (sound velocity × density) of the solvent, which has a significant influence. In this embodiment, a second organic solvent with high acoustic impedance is included among the multiple organic solvents. This improves the intensity of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent M, and the sintered powder material P can be more effectively removed.

[0038] Furthermore, the intensity of cavitation increases when the viscosity of the solvent is low. In this embodiment, a third organic solvent with low viscosity is included among the multiple organic solvents. This improves the intensity of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent M, and the sintered powder material P can be more effectively removed.

[0039] Thus, in this embodiment, by mixing multiple organic solvents, the frequency and intensity of cavitation can be improved in terms of physical properties such as vapor pressure and acoustic impedance. Therefore, the sintered powder material P can be removed more effectively. In particular, in this embodiment, sintered powder material P remaining in a narrow, bottomed internal channel (for example, hole 21 in this embodiment) can be effectively removed. Furthermore, it is particularly effective when fabricating three-dimensional objects from metals (for example, copper or copper alloys) that have a low melting point and low laser absorption rate, and which are prone to generating sintered powder material P.

[0040] Furthermore, if the metal additive manufactured body 20 is immersed in water, there is a possibility that the metal additive manufactured body 20 may corrode during cleaning. On the other hand, in this embodiment, the metal additive manufactured body 20 is immersed in an organic solvent. By using an organic solvent that does not corrode metal, corrosion of the metal additive manufactured body 20 during cleaning can be suppressed.

[0041] Furthermore, in this embodiment, the metal additively manufactured body 20 is subjected to dry vibration before ultrasonic U cleaning. This allows for the efficient generation of cavitation in the mixed solvent M, which has high vapor pressure and acoustic impedance, after securing an entry path for the mixed solvent M through dry vibration. Therefore, the sintered powder material P can be suitably removed.

[0042] This disclosure is not limited to the embodiments described above, and can be modified as appropriate without departing from its essence.

[0043] For example, the ultrasonic generator 13 may transmit ultrasonic waves of multiple different frequencies. For instance, if the higher frequency is an integer multiple of the lower frequency, a larger amplitude can be generated. Therefore, the sintered powder material P can be removed more effectively. Furthermore, if the higher frequency is not an integer multiple of the lower frequency, amplitude unevenness in the mixed solvent M can be suppressed. Therefore, unwanted powder can be effectively removed from the metal additively manufactured body 20.

[0044] Furthermore, for example, the ultrasonic generator 13 may vary the frequency of the ultrasonic waves it transmits at a predetermined period. By using an ultrasonic generator with a sweep function that varies the frequency of the irradiated ultrasonic waves at a constant period, the generation of standing waves, in which the positions of the antinodes and nodes of the amplitude are constant, can be suppressed. Therefore, the location of cavitation can be varied. Thus, uneven cleaning can be suppressed.

[0045] Furthermore, the cleaning device 10 may include a vibrating unit (not shown) that vibrates the metal additive manufactured body 20 housed in the inner container 12 in the vertical direction. This allows the metal additive manufactured body 20 to move vertically, thereby changing the areas where the ultrasonic waves hit at high amplitudes and areas where they hit at low amplitudes. Consequently, uneven cleaning of the metal additive manufactured body 20 can be suppressed.

[0046] Furthermore, the cleaning device 10 may include a depressurization section (not shown) that alternately repeats depressurization and release to the atmosphere inside the inner container 12. By repeatedly reducing the pressure inside the inner container 12 and releasing it to the atmosphere, the mixed solvent M inside the inner container 12 moves. This makes it easier for the mixed solvent M to flow into narrow parts of the metal additive manufacturing body 20, for example. The mixed solvent M that has flowed in pushes the powder material out of the narrow parts. Thus, the powder material can be removed effectively. Furthermore, the inflow of the mixed solvent M into the confined space makes it easier to generate cavitation within that space. Therefore, the sintered powder material P can be removed more effectively. Furthermore, if the pressure inside the inner container 12 is reduced too much, cavitation will occur. foam The frequency of this occurs decreases significantly. This is because the gas generated is released due to the effect of reduced pressure. foam This is thought to be because the powder escapes from the liquid before it can be removed. Therefore, the reduced pressure value may be determined by considering both the cavitation intensity and the degree of penetration of the mixed solvent M, depending on the powder to be removed.

[0047] Furthermore, although the above embodiment described an example using a mixed solvent obtained by mixing three types of organic solvents, a first organic solvent, a second organic solvent, and a third organic solvent, the mixed solvent only needs to contain the first and second organic solvents, and the number of organic solvents to be mixed is not limited to three types. For example, the number of organic solvents to be mixed may be only two types, the first organic solvent and the second organic solvent. Organic solvents other than the first, second, and third organic solvents may also be mixed.

[0048] The cleaning apparatus and cleaning method described in the embodiments above can be understood, for example, as follows.

[0049] A cleaning apparatus according to a first aspect of the present disclosure is a cleaning apparatus (10) for cleaning a metal additive manufactured body (20) formed by stacking layers of metal powder material, some of which are melt-bonded or sintered by irradiation with laser light, the cleaning apparatus (10) comprising: a housing section (12) filled with a mixed solvent (M) which is a liquid mixture of a plurality of organic solvents, for housing the metal additive manufactured body immersed in the mixed solvent; and an ultrasonic transmitting section (13) for transmitting ultrasonic waves (U) to the metal additive manufactured body housed in the housing section, wherein the plurality of organic solvents include a first organic solvent having a higher vapor pressure than the other organic solvents, and a second organic solvent having a higher acoustic impedance than the other organic solvents.

[0050] In the above configuration, ultrasonic waves are transmitted to the metal additively manufactured body while it is immersed in a mixed solvent. This allows, for example, the metal additively manufactured body to detect narrow areas. The place Even in this case, the mixed solvent flows into the confined space. Therefore, the powder material remaining in the confined space can be removed by the flowing mixed solvent. Furthermore, in the above configuration, cavitation is generated in the mixed solvent by ultrasound. The high-pressure, high-speed flow of the mixed solvent generated when bubbles form in the mixed solvent collides with the sintered powder material, thereby crushing the sintered powder material. This allows the sintered powder material to be removed. Thus, with the above configuration, unwanted powder can be effectively removed from the metal additively manufactured body.

[0051] Furthermore, the frequency of cavitation is primarily influenced by the ease of evaporation of the solvent (high vapor pressure). In the above configuration, a first organic solvent with high vapor pressure is included among the multiple organic solvents. This improves the frequency of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent, allowing for more favorable removal of sintered powder material. The first organic solvent is preferably an organic solvent whose vapor pressure is 2.5 kPa or higher at room temperature. For example, the first organic solvent may be acetone.

[0052] Furthermore, the intensity of cavitation is dominated by the acoustic impedance (sound velocity × density) of the solvent, which has a significant influence. In the above configuration, a second organic solvent with high acoustic impedance is included among the multiple organic solvents. This can improve the intensity of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent, and the sintered powder material can be more effectively removed. The second organic solvent is, for example, one with an acoustic impedance of 700 kPa·s / m at room temperature. 3 The above-mentioned organic solvent is preferable. For example, the second organic solvent may be methyl ethyl ketone, isopropyl alcohol, or ethanol.

[0053] Thus, with the above configuration, by mixing multiple organic solvents, the frequency and intensity of cavitation can be improved in terms of physical properties such as vapor pressure and acoustic impedance. Therefore, sintered powder material can be removed more effectively.

[0054] Furthermore, if the metal additive manufactured object is immersed in water, there is a possibility that the object may corrode during cleaning. On the other hand, in the above configuration, the metal additive manufactured object is immersed in an organic solvent. As a result, if an organic solvent that does not corrode metal is used, corrosion of the metal additive manufactured object during cleaning can be suppressed.

[0055] Furthermore, in the cleaning apparatus according to the second aspect of this disclosure, in the first aspect, the plurality of organic solvents include a third organic solvent with a lower viscosity than the other organic solvents.

[0056] The intensity of cavitation increases when the viscosity of the solvent is low. In the above configuration, a third organic solvent with low viscosity is included among the multiple organic solvents. This can improve the intensity of cavitation. Therefore, cavitation can be more easily generated in the mixed solvent, and the sintered powder material can be more effectively removed. The third organic solvent is preferably an organic solvent whose viscosity is 1.0 mPas or less at room temperature. For example, the third organic solvent may be n-hexane, n-pentane, or ether.

[0057] Furthermore, in the cleaning apparatus according to the third aspect of this disclosure, the ultrasonic transmitting unit transmits ultrasonic waves of multiple different frequencies, as described in the first or second aspect.

[0058] In the above configuration, the ultrasonic transmitting unit transmits ultrasonic waves of multiple different frequencies. This allows for the generation of larger amplitudes, for example, when the higher frequency is an integer multiple of the lower frequency. Furthermore, when the higher frequency is not an integer multiple of the lower frequency, amplitude unevenness in the mixed solvent can be suppressed. Therefore, unwanted powder can be effectively removed from the metal additively manufactured body.

[0059] Furthermore, in the cleaning apparatus according to the fourth aspect of this disclosure, in any of the first to third aspects described above, the ultrasonic transmitting unit varies the frequency of the ultrasonic waves to be transmitted at a predetermined period.

[0060] In the above configuration, the ultrasonic transmitting unit varies the frequency of the transmitted ultrasonic waves at a predetermined period. This suppresses the generation of standing waves. Therefore, the location of cavitation can be varied. Thus, uneven cleaning of metal additively manufactured bodies can be suppressed.

[0061] Furthermore, the cleaning apparatus according to the fifth aspect of this disclosure includes a vibrating unit that vibrates the metal additive manufactured body housed in the housing unit in the vertical direction, in any of the first to fourth aspects described above.

[0062] The above configuration includes a vibrating unit that vibrates the metal additive manufactured object housed in the housing unit in the vertical direction. As a result, the metal additive manufactured object moves vertically, which allows the areas where the ultrasonic amplitude is high and the areas where the amplitude is low to be varied. Therefore, uneven cleaning of the metal additive manufactured object can be suppressed.

[0063] Furthermore, the cleaning apparatus according to the sixth aspect of this disclosure includes a depressurization unit that alternately repeats depressurization and release to the atmosphere inside the housing section, in any of the first to fifth aspects described above.

[0064] The above configuration includes a vacuum section that reduces the pressure inside the containment section and releases it to the atmosphere. By repeatedly reducing the pressure inside the containment section and releasing it to the atmosphere alternately, the mixed solvent inside the containment section moves. This makes it easier for the mixed solvent to flow into narrow areas, for example. The mixed solvent that has flowed in pushes the powder material out of the narrow areas. Therefore, the powder material can be removed effectively. Furthermore, the inflow of the mixed solvent into the confined space makes it easier to generate cavitation within that space. Therefore, the sintered powder material can be removed more effectively.

[0065] A cleaning method according to a first aspect of the present disclosure is a cleaning method for a metal additive body (20) formed by stacking layers of metal powder material, some of which are melt-bonded or sintered by irradiation with laser light, and comprising: a storage step of storing the metal additive body in a storage section (12) which is filled with a mixed solvent (M) which is a liquid mixture of a plurality of organic solvents, while immersed in the mixed solvent; and an ultrasonic transmission step of transmitting ultrasonic waves from an ultrasonic transmitting section (13) to the metal additive body stored in the storage section, wherein the plurality of organic solvents include a first organic solvent having a higher vapor pressure than the other organic solvents, and a second organic solvent having a higher acoustic impedance than the other organic solvents. [Explanation of symbols]

[0066] 10: Washing device 11:Outer container 11a: Outer container body part 11b: Outer container bottom part 12:Inner container 12a: Inner container body part 12b: Inner container bottom part 12c: Lid part 13: Ultrasonic generator 14: Perforated plate 20: Metal additive manufacturing 21: Hole A: Arrow B: Air bubbles M:Mixed solvent P: Powder material U:Ultrasonic W:Water

Claims

1. A cleaning device for cleaning a metal additive manufacturing body, which is formed by layering layers of metal powder material, some of which are melted or sintered by irradiating them with laser light, A housing section is filled with a mixed solvent, which is a liquid mixture of multiple organic solvents, and houses the metal additive manufactured body immersed in the mixed solvent. The system comprises an ultrasonic transmitting unit that transmits ultrasonic waves to the metal additive manufactured body housed in the aforementioned housing, A cleaning apparatus comprising a plurality of organic solvents, the first organic solvent having a higher vapor pressure than the other organic solvents, and the second organic solvent having a higher acoustic impedance than the other organic solvents.

2. The cleaning apparatus according to claim 1, wherein the plurality of organic solvents include a third organic solvent with a lower viscosity than the other organic solvents.

3. The cleaning apparatus according to claim 1, wherein the ultrasonic transmitting unit transmits ultrasonic waves of multiple different frequencies.

4. The cleaning apparatus according to claim 1, wherein the ultrasonic transmitting unit varies the frequency of the ultrasonic waves to be transmitted at a predetermined period.

5. The cleaning apparatus according to claim 1, further comprising a vibrating unit for vibrating the metal additive manufactured body housed in the housing unit in the vertical direction.

6. The cleaning apparatus according to claim 1, further comprising a depressurization unit that alternately repeats depressurization and release to the atmosphere inside the containment unit.

7. A cleaning method for a metal additive manufacturing body formed by stacking layers of metal powder material, some of which are melted or sintered by irradiating them with laser light, A housing step involves housing the metal additive manufactured body in a housing section, which is filled with a mixed solvent, which is a liquid mixture of multiple organic solvents, while immersed in the mixed solvent. The system includes an ultrasonic transmission step of transmitting ultrasonic waves from an ultrasonic transmission unit to the metal additive manufactured body housed in the housing section, A washing method comprising a plurality of organic solvents, the first organic solvent having a higher vapor pressure than the other organic solvents, and the second organic solvent having a higher acoustic impedance than the other organic solvents.

Images