FR3133550A1 - Operating method of a laser powder bed fusion system - Google Patents

Abstract

Method of operating a laser powder bed fusion system in which at least one layer of powder is spread using a scraper (17) and at least one sound emitted by said system is captured during the spreading, in which said captured sound (25) is compared to other sounds from a database (27) comprising normal reference sounds emitted during normal operation of said system and abnormal reference sounds emitted during a malfunction in the spreading of the powder layer, so as to determine whether said sound corresponds to a normal sound or an abnormal sound Abstract figure: Figure 2

Description

Operating method of a laser powder bed fusion system

The invention relates to the field of additive manufacturing, and in particular additive manufacturing by selective laser fusion on a powder bed, also known by the English name Laser Beam Melting ( LBM ) or Selective Laser Melting ( SLM ) . ).

More specifically, the invention relates to a method of operating a laser powder bed fusion system.

A method is known in the art which consists of manufacturing at least one part, in particular one or more metal part(s), by melting successive layers of powder by means of a laser beam controlled by a processing system. the information in which the three-dimensional coordinates of the points of the successive layers to be produced to form said parts have been recorded.

There illustrates a manufacturing device 1 intended to implement such a method.

The manufacturing device 1 comprises a reservoir 3 containing a metal powder 5 and the bottom 7 of which is mobile, movable in translation vertically by a rod 9 of a jack, and a neighboring tank 11, substantially parallelepiped, the bottom of which is constituted by a mobile plate 13, movable in translation vertically by a rod 15 of a second cylinder.

The manufacturing device 1 further comprises a scraper 17 making it possible to bring powder from the reservoir 3 to the tank 11, the scraper 17 being movable in translation along a horizontal plane A substantially parallel to the plate 13. The manufacturing device 1 manufacturing 1 further comprises means 18 for generating a laser beam 19, coupled to a device 20 for moving said laser beam 19 making it possible to orient it and/or move it to reach any point of the tank 11 .

To manufacture one or more parts 21, a first layer of powder is placed in the tank 11 using the scraper 17.

The layer then has a lower surface corresponding to the surface of the plate 13 and an upper surface on which the laser beam 19 is directed and moved. The energy provided by this beam causes the local fusion of the powder which, by solidifying, forms a first layer of the or each piece 21.

After formation of this first layer, the plate 13 is lowered by a distance corresponding to the thickness of a layer of powder, while the bottom 7 of the reservoir 3 is raised by a corresponding height, so that a certain quantity of powder 22 is located above the horizontal plane A.

Then, this quantity of powder 22 is brought by the scraper 17, from the tank 3 into the tank 11, to form a second layer on top of the previous layer. In the same manner as previously, a second layer of each part 21 is formed using the laser beam 19. The quantity of powder and the positions of the bottom 7 and the plate 13 are determined so as to form layers of powder of 'a chosen and constant thickness.

These operations are repeated until the parts 21 are completely manufactured.

However, there is no way to detect possible problems during the production of the part. More precisely, there is no way to detect an incident such as an impact on the part or a non-uniform deposit of a layer of powder which would degrade the quality of the part to be manufactured.

Summary

This disclosure improves the situation.

A method of operating a laser powder bed fusion system is proposed in which at least one layer of powder is spread using a scraper and at least one sound emitted by said system is captured during the process. spreading, in which said captured sound is compared to other sounds from a database comprising normal reference sounds emitted during normal operation of said system and abnormal reference sounds emitted during a malfunction of the spreading the powder layer, so as to determine whether said sound corresponds to a normal sound or an abnormal sound.

The sensor used to capture the sound can be a sound level meter.

The present method makes it possible to detect a possible problem when spreading the powder in a laser powder bed fusion system. This process thus makes it possible to anticipate a possible blockage of the scraper and therefore to make corrections when possible before stopping the production of a part.

The database can be at least partly constituted by capturing sounds emitted by the laser fusion system concerned during previous spreading of powder layers.

These sounds captured in the database make it possible to discriminate in what type of operation the scraper is, namely normal operation or a malfunction in the spreading of the powder layer.

If it can be determined that the sound picked up is an abnormal sound, then the spreading of the powder layer can be stopped.

Conversely, if it can be determined that the sound captured is a normal sound, then the spreading of the powder layer can be continued.

• son d’une courte durée et d’une forte intensité sonore ;
• son constant et d’une intensité sonore moyenne ;
• combinaison d’un son de courte durée et forte intensité sonore avec un son constant et d’intensité sonore moyenne ;
• son d’intensité sonore faible.

Abnormal baseline sounds may include at least one sound belonging to one of the following categories:

• sound of short duration and high sound intensity;
• constant sound and medium loudness;
• combination of a short duration and high intensity sound with a constant sound and medium intensity sound;
• low loudness sound.

The sound intensity of an abnormal reference sound may be greater than the sound intensity of a normal reference sound, in particular by at least 10db.

The majority or all of the abnormal reference sounds may belong to at least one of the above categories.

These abnormal sounds referenced in the database allow the identification of an anomaly during the spreading of the powder layer.

Normal reference sounds may include at least one linear sound of low sound intensity.

Most or all normal reference sounds may be of such a type.

According to another aspect, a powder bed laser fusion system is proposed to implement the method as described above, the system comprising a sound sensor, preferably a sound level meter.

Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

shows a schematic side view of an additive manufacturing device of the state of the art.

shows a schematic side view of an additive manufacturing device, according to the invention.

There shows a device for spreading a layer of powder by a scraper 17 in a laser fusion system. This device is similar to that described in the prior art with a few differences. This powder spreading device includes a sensor 25 capable of capturing sound, called a sound level meter. This sound level meter includes a database 27.

This document relates to a method of operating said laser powder bed fusion system. At least one layer of powder is spread using the scraper 17. When said at least one layer is spread, a sound is emitted. This sound is then picked up by the sound level meter.

The sound level meter database 27 is created by capturing sounds emitted by the laser fusion system during previous uses of said system and therefore during previous spreading of layers of powder. In this database 27 different types of sounds are listed. If the sound is normal reference, then this normal reference sound is linear with low sound intensity. By normal reference sound, we mean a sound emitted by the scraper 17 during normal operation of said scraper. Conversely, if the sound is abnormal by reference, then different categories of abnormal sounds can be identified. By abnormal reference sound, we mean a sound emitted by the scraper 17 during a malfunction in the spreading of the powder layer. These abnormal reference sounds may include a short duration, high intensity sound that may be emitted when the scraper collides with a part. Reference abnormal sounds may include a constant, medium-loud sound that may be emitted when the scraper scrapes against a surface. The average sound intensity of the reference abnormal sound when the scraper rubs against a support is lower than the sound intensity of the reference abnormal sound when the scraper collides with a part. Abnormal baseline sounds may include either a combination of a short-duration, high-intensity sound with a constant, medium-intensity sound. Finally, abnormal reference sounds may include a low or no sound intensity sound when the laser fusion system is shut down.

The sound emitted by the scraper 17 and picked up by the sound level meter is compared to the normal and abnormal reference sounds included in the database so as to determine whether said sound corresponds to a normal sound or an abnormal sound. If the sound picked up by the sound level meter is an abnormal sound, then the spreading of the powder layer is interrupted. On the other hand, if the sound picked up by the sound level meter is a normal sound, then the spreading of the powder layer is continued.

Claims (6)

Method of operating a laser powder bed fusion system in which at least one layer of powder is spread using a scraper (17) and at least one sound emitted by said system is captured during the spreading, in which said captured sound (25) is compared to other sounds from a database (27) comprising normal reference sounds emitted during normal operation of said system and abnormal reference sounds emitted during a malfunction in the spreading of the powder layer, so as to determine whether said sound corresponds to a normal sound or an abnormal sound. Method according to the preceding claim, in which the database (27) is at least partly constituted by capturing sounds emitted by the laser fusion system concerned during previous spreading of layers of powder. Method according to one of the preceding claims, wherein, if it is determined that the captured sound (25) is an abnormal sound, then the spreading of the powder layer is interrupted. Method according to one of the preceding claims, in which the sound intensity of the abnormal reference sounds is greater than the sound intensity of the normal reference sounds, in particular by at least 10 db. Method according to one of the preceding claims, in which the normal reference sounds comprise at least one linear sound of low sound intensity. Laser powder bed fusion system for implementing the method according to any one of the preceding claims, the system comprising a sound sensor, preferably a sound level meter.