Dust removal device and dust removal process

Abstract

Powder Removal Device and Powder Removal Method. Device (200) for removing powder from parts obtained by additive manufacturing, said device comprising: a vibrator (203); a support plate (202) attached to a part to be powder removed (201); said device (200) being characterized in that it comprises a first damper (204) and a connecting plate (205) linking the vibrator (203) and the support plate (202), said first damper (204) being in contact with the connecting plate (205) and having a cutoff frequency fc lower than fp, fp being a first natural frequency of the part to be powder removed (201). Figure to be published with the abbreviation: Figure 3

Description

Title of the invention: Dust removal device and dust removal method TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of additive manufacturing and in particular that of depowdering of parts obtained by additive manufacturing on a powder bed.

[0002] One object of the present invention relates to a device for removing powder from parts obtained by additive manufacturing on a powder bed. Another object of the invention relates to a method for removing powder from parts obtained by additive manufacturing on a powder bed. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Parts produced by powder bed fusion often require post-processing to remove excess powder, particularly when the parts have internal cavities or complex geometries. One solution known to those skilled in the art involves using vibrations to detach the excess manufacturing powder. For this purpose, the assembly consisting of the melting platform and the part is removed from the machine after cooling and then placed in a depowdering device to perform a depowdering step on the part.

[0004] However, cracks can form during vibratory powder removal, and this has been observed for various types of parts and materials. In these cases, the vibration level experienced by the parts at their natural frequency is too high. Furthermore, the operation of the vibrator used during powder removal does not allow for modulation of the vibration level or the applied frequency. Summary of the invention

[0005] The invention offers a solution to the problems mentioned above, by describing a vibration depowdering device capable of controlling the vibrations applied to the part to be depowdered, so as to eliminate the formation of cracks in the part to be depowdered.

[0006] A first aspect of the invention relates to a device for depowdering parts obtained by additive manufacturing on a powder bed, said device comprising: • a vibrator; • a support plate attached to a part to be de-powdered; said device further comprising a first damper and a connecting plate linking the vibrator and the support plate, said first damper being in contact with the connecting plate and having a cutoff frequency fc lower than fp, fp being a first natural frequency of the part to be dusted.

[0007] A vibrator is understood to be a device capable of generating a vibration at a given frequency or at a plurality of given frequencies.

[0008] A support plate is defined as a plate that is integral with a part obtained by powder bed additive manufacturing. An example of a support plate is a build platform for powder bed additive manufacturing.

[0009] A damper is defined as a device having a resonant frequency and capable of transmitting the vibrations produced by the vibrator. For example, the vibrator is made of an elastomeric material.

[0010] The cutoff frequency fc of the first damper is understood to be the frequency at which the vibrations generated by the vibrator are attenuated. In other words, a cutoff frequency refers to the frequency at which the impulse response of a filter begins to drop off. Thus, for low-pass filters, frequencies below the cutoff are retained and frequencies above the cutoff are attenuated.

[0011] Advantageously, the depowdering device according to a first aspect of the invention makes it possible to apply a sufficiently high level of vibration to remove excess powder, while avoiding damage to the parts obtained by additive manufacturing on a powder bed.

[0012] Advantageously, the depowdering device according to the first aspect of the invention applies vibrations having a frequency lower than the first natural frequency fp of the part to be depowdered, which limits the level of acceleration to which the part to be depowdered is subjected while ensuring effective depowdering.

[0013] Advantageously, the first damper has a cutoff frequency fc lower than the first natural frequency fp of the part to be depowdered. The damper therefore makes it possible to attenuate vibrations at frequencies close to the first natural frequency fp of the part to be depowdered and to limit the level of acceleration experienced by the part to be depowdered, which eliminates the risk of cracking of the part to be depowdered.

[0014] In addition to the characteristics mentioned in the preceding paragraphs, the device according to the first aspect of the invention may have one or more additional characteristics among the following: • the first shock absorber is made of elastomeric material; • the difference between the first natural frequency fp of the part to be depowdered and the cutoff frequency fc of the damper is greater than 50 Hz; advantageously, this characteristic makes it possible to subsequently reduce the risk of cracking of the part to be depowdered; • the first shock absorber is positioned between the vibrator and the connecting plate; Advantageously, this location of the vibrator makes it possible to limit the weight supported by the first shock absorber; • the device further includes a lower plate, the lower plate and the connecting plate being separated by a set of second dampers; advantageously, the second dampers make it possible to attenuate the vibrations by preventing them from being transmitted to the ground; • the first shock absorber is positioned between the connecting plate and the support plate; • the device comprises a plurality of first dampers, said plurality of first dampers comprising a number of first dampers greater than or equal to one; • The support plate is a melting platform for powder bed additive manufacturing.

[0015] A second aspect of the invention relates to a method for depowdering parts obtained by additive manufacturing on a powder bed, said method comprising the following steps: • determination of the first natural frequency of a part to be depowdered; • Installation of a first shock absorber configured to transmit the vibrations vibrations of a vibrator to a support plate, said support plate being integral with the part to be depowdered, the cut-off frequency of the first damper being lower than the first natural frequency of the part to be depowdered; • vibrating the vibrator at a vibration frequency less than or equal to the cutoff frequency of the first shock absorber.

[0016] Advantageously, the method according to a second aspect of the invention makes it possible to choose a vibration frequency lower than the first natural frequency of the part to be depowdered, which prevents the formation of cracks in the part while allowing its depowdering in an efficient manner.

[0017] In addition to the characteristics mentioned in the preceding paragraphs, the method according to the second aspect of the invention may have one or more additional characteristics from among the following: • the step of vibrating the vibrator is followed by at least one other step including vibrating at another vibration frequency less than or equal to the cutoff frequency of the first damper; • The step of installing a first shock absorber also includes the positioning of a set of first shock absorbers. BRIEF DESCRIPTION OF THE FIGURES

[0018] The figures are presented for illustrative purposes only and are in no way limiting to the invention: • Fig. 1a illustrates the transfer function of an elastomer damper used in the dust removal device according to a first aspect of the invention; • Figure [1b] illustrates the Bode plot of an elastomeric damper used in the dust removal device according to the first aspect of the invention • Figure 2 illustrates one embodiment of the dust removal device according to the first aspect of the invention; • Figure 3 illustrates another embodiment of the dust removal device according to the first aspect of the invention; • Figure 4 illustrates the depowdering process according to a second aspect of the invention. DETAILED DESCRIPTION

[0019] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0020] Figure [Fig. 1a] illustrates the frequency response or transfer function H of a An elastomeric damper is used in the dust removal device according to a first aspect of the invention. The x-axis represents the natural frequency of the vibrating system, equal to 2 times PI multiplied by the natural frequency. The y-axis represents the gain of the transfer function of the damping system, reflecting the amplification (>1) or attenuation (<1) of the system.

[0021] The resonance frequency wO of the damper is indicated by the vertical dashed line.

[0022] The behavior of an elastomeric damper is described below: • before its resonance frequency w0, the damper does not filter the acceleration and transmits it entirely to the fusion plate; • at its resonant frequency, the damper amplifies the acceleration with a factor between 5 and 10; • after its resonance frequency, it attenuates the acceleration with a slope, for example -20DB / decade, as illustrated by the Bode diagram shown in [Fig.lb].

[0023] Figure 2 illustrates an embodiment of the depowdering device 200 according to a first aspect of the invention. The depowdering device 200 comprises a part to be depowdered 201 obtained by additive manufacturing. It further comprises a support plate 202 integral with the part 201. For example, the support plate 202 is a melting platform for powder bed fusion, integral with the part 201.

[0024] The device 200 according to the first aspect of the invention further comprises a vibrator 203 and a first damper 204. According to the embodiment illustrated in [Fig.2], the device 200 comprises a plurality of first dampers 204.

[0025] According to one embodiment, the first shock absorbers 204 are made of elastomer material.

[0026] The device 200 illustrated in [Fig.2] further includes a connecting plate 205 linking the vibrator 203 and the support plate 202. The first dampers 204 are placed between the connecting plate 205 and the support plate 202 so as to transmit the vibrations of the vibrator 203 to the support plate 202 and to the part to be depowdered 201, while attenuating the vibrations having frequencies higher than the cutoff frequency of the dampers 204.

[0027] The cutoff frequency of the first dampers 204 is lower than the first natural frequency of the part to be depowdered 201. Advantageously, this makes it possible to reduce the level of acceleration seen by the part to be depowdered 201, while ensuring the depowdering of the part.

[0028] According to an embodiment of the device 200 according to the first aspect of the invention, the difference between the cutoff frequency of the first dampers 204 and the first natural frequency of the part to be depowdered 201 is greater than or equal to 50 Hz. Advantageously, this difference between the cutoff frequency of the first dampers 204 and the first natural frequency of the part to be depowdered 201 makes it possible to reduce the risk of cracking of the part to be depowdered.

[0029] The device 200 according to the first aspect of the invention further comprises a lower plate 206 and a set of second shock absorbers 207, said second shock absorbers 207 being arranged between the connecting plate 205 and the lower plate 206.

[0030] Advantageously, the second shock absorbers 207 make it possible to reduce the transmission of vibrations from the vibrator to the ground.

[0031] Figure 3 illustrates another embodiment of the device 200 according to the first aspect of the invention. In this case, the first shock absorbers 204 are in contact with the vibrator 203 and placed between the vibrator 203 and the connecting plate 205.

[0032] Advantageously, the first shock absorbers 204 used in this embodiment only have to support the weight of the vibrator 203, which reduces the mechanical stresses in the manufacture of said first shock absorbers 204.

[0033] Fig. 4 schematically illustrates the steps of the 300 process for depowdering parts obtained by additive manufacturing on a powder bed.

[0034] The method 300 according to a second aspect of the invention includes a step 301 of determining the first natural frequency of the part to be depowdered.

[0035] The method 300 according to the second aspect of the invention further comprises a step 302 of installing a first damper configured to transmit the vibrations of a vibrator to a support plate, said support plate being integral with the part to be depowdered, the cutoff frequency of the first damper being in- lower than the first natural frequency of the part to be dedusted.

[0036] Advantageously, this step allows the use of a first damper having a chosen cutoff frequency in order to dampen vibrations at a natural frequency of the part and which could damage the part during depowdering.

[0037] According to one embodiment of process 300, step 302 of setting up a first damper further includes the positioning of a set of first dampers.

[0038] The method 300 according to the second aspect of the invention further includes a step 303 of vibrating the vibrator at a vibration frequency less than or equal to the cutoff frequency of the first damper.

[0039] According to one embodiment, step 303 is followed by at least one other step comprising vibrating at another vibration frequency less than or equal to the cutoff frequency of the first damper.

Claims

Demands

1. Assembly comprising a device (200) for depowdering parts obtained by additive manufacturing on a powder bed and a part to be depowdered (201) obtained by additive manufacturing on a powder bed, said device comprising: • a vibrator (203); • a support plate (202) integral with the part to be depowdered (201); • said device (200) being characterized in that it comprises a first damper (204) and a connecting plate (205) connecting the vibrator (203) and the support plate (202), said first damper (204) being in contact with the connecting plate (205) and having a cutoff frequency fc lower than fp, fp being a first natural frequency of the part to be depowdered (201).

2. Assembly according to the preceding claim characterized in that the first shock absorber (204) is made of elastomeric material.

3. Assembly according to any one of the preceding claims characterized in that the difference between the first natural frequency of the part to be depowdered (201) and the cutoff frequency of the first damper (204) is greater than or equal to 50 Hz.

4. Assembly according to any one of the preceding claims characterized in that the first damper (204) is disposed between the vibrator (203) and the connecting plate (205).

5. Assembly according to any one of claims 1 to 3 characterized in that the first shock absorber (204) is disposed between the connecting plate (205) and the support plate (202).

6. Assembly according to any one of the preceding claims characterized in that the support plate (202) is a melting platform for powder bed additive manufacturing.

7. Method (300) for depowdering a part obtained by additive manufacturing on a powder bed, said method (300) comprising the following steps: • determination (301) of the first natural frequency of the part to be depowdered; • setting up a first damper (302) configured to transmit the vibrations of a vibrator to a support plate, said support plate being attached to the part to be depowdered, the cut-off frequency of the first damper being less than a first natural frequency of the part to be depowdered; • setting the vibrator to vibration (303) at a vibration frequency less than or equal to the cut-off frequency of the first damper.

8. Method (300) according to the preceding claim characterized in that the step of vibrating (303) the vibrator is followed by at least one other step comprising vibrating at another vibration frequency less than or equal to the cutoff frequency of the first damper.

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