JP7362433B2 - Additive manufacturing method - Google Patents

Description

The present invention relates to an additive manufacturing method.

The additive manufacturing method is a method of forming a three-dimensional additive-molded product by repeatedly layering raw material powder in a modeling box and solidifying a predetermined area of the layer each time the layer is laminated.

After forming the additively manufactured product in the modeling box, remove the additively manufactured product from the modeling box and remove unsolidified raw material powder (hereinafter also referred to as "unsolidified powder") that has adhered to the surface of the additively manufactured product. There is a need. For example, in Patent Document 1 listed below, after forming a layered product in a modeling box, the layered product is taken out from the modeling box and placed in a metal powder removal chamber equipped with a jet nozzle, and high-pressure gas is injected from the jet nozzle. By doing this, metal powder adhering to the additively manufactured product is removed.

Japanese Patent Application Publication No. 2018-80356

However, the above method requires a space for installing a metal powder removal chamber, which increases the size of the additive manufacturing equipment. In addition, it is necessary to move the additively manufactured product from the modeling box to the metal powder removal chamber, which is time-consuming, and there is a risk of powder adhering to the additively manufactured product scattering and damage to the additively manufactured product during movement.

Therefore, the present invention aims to downsize additive manufacturing equipment, reduce the number of man-hours in additive manufacturing, prevent scattering of raw material powder, and prevent damage to additively manufactured products.

In order to solve the above problems, the present invention creates an additively manufactured product by stacking raw material powder layers in a modeling box and solidifying a predetermined area of the raw material powder layers each time the raw material powder layers are laminated. A lamination process comprising: a modeling step of forming, a discharge step of discharging raw material powder that has not solidified from the modeling box, and a cleaning step of removing raw material powder adhering to the surface of the layered product in the modeling box. Provide a modeling method.

In this way, in the additive manufacturing method according to the present invention, the inside of the modeling box is utilized as a space for performing the cleaning process of the additively manufactured product. This eliminates the need for a separate space for the cleaning process, allowing the additive manufacturing equipment to be downsized. Furthermore, since there is no need to move the additively manufactured product from the modeling box to the cleaning area, the number of man-hours is reduced, and it is possible to avoid scattering of raw material powder and damage to the additively manufactured product due to movement of the additively manufactured product.

In the discharge process, if the unsolidified powder is discharged from the hole provided at the bottom of the modeling box, a space for performing the cleaning process can be easily secured in the modeling box.

As described above, according to the present invention, it is possible to downsize additive manufacturing equipment, reduce the number of man-hours in additive manufacturing, prevent scattering of raw material powder, and prevent damage to additively manufactured products.

FIG. 1 is a top view of an additive manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II of the additive manufacturing apparatus in FIG. 1. FIG. It is a sectional view of a closing member. It is a top view showing the process of forming a raw material powder layer on a modeling table. 5 is a cross-sectional view (cross-sectional view taken along the line VV in FIG. 4) showing a process of forming a raw material powder layer on a modeling table. FIG. It is a top view which shows the process of solidifying the predetermined area|region of the said raw material powder layer. FIG. 7 is a cross-sectional view (cross-sectional view taken along the line VII-VII in FIG. 6) showing a step of solidifying a predetermined region of the raw material powder layer. It is a sectional view showing a process of further laminating a raw material powder layer on the raw material powder layer. FIG. 3 is a cross-sectional view showing a step of solidifying a predetermined region of stacked raw material powder layers. It is a sectional view showing a state where a layered product is formed. FIG. 3 is a cross-sectional view showing how unsolidified powder is discharged from the modeling box. FIG. 3 is a cross-sectional view showing how unsolidified powder adhering to the surface of a layered product is removed in the modeling box.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIGS. 1 and 2, the additive manufacturing apparatus according to an embodiment of the present invention includes a modeling box 10 having a modeling table 11 at the bottom, a recoater 20 as a raw material powder supply section, and a binder as a solidification section. Supply section 30, destruction means 40, modeling table 11, recoater 20, drive means (not shown) that drives the binder supply section 30 and destruction means 40, respectively, and a control section (not shown) that controls these drive means. Equipped with.

The modeling box 10 includes a modeling table 11 and a side wall 12 surrounding the modeling table 11. In this embodiment, the modeling table 11 and the side wall 12 have a rectangular shape in plan view (see FIG. 1). The modeling table 11 is raised and lowered by a driving means such as an electric cylinder.

The modeling table 11 includes a table main body 13 in which a hole 13a is formed, and a closing member 14 that closes the hole 13a. The number of holes 13a provided in the table body 13 is not particularly limited, and for example, a plurality of holes 13a may be provided, specifically in multiple rows and rows (in the example shown in FIG. 1, three columns and four rows). A hole 13a is provided. One closing member 14 is provided in each hole 13a. In this embodiment, the inner circumferential surface of the hole 13a and the outer circumferential surface of the closing member 14 form a tapered shape whose diameter gradually decreases downward, and the two are tapered fitted (see FIG. 2). The upper surface of the closing member 14 is arranged at the same height as the upper surface of the table main body 13 or slightly below the upper surface of the table main body 13.

The closing member 14 is formed of the same raw material powder as the raw material powder of the laminate-molded product, and is manufactured, for example, by the same method as the laminate-molded product P described later. As shown in FIG. 3, the closure member 14 of this embodiment has a solidified layer 14a formed by solidifying raw material powder formed on its surface, and an unsolidified raw material powder 14b sealed inside the solidified layer 14a. In this case, the strength of the closing member 14 can be adjusted depending on the thickness of the solidified layer 14a. It should be noted that the closing member 14 may be formed of a material different from the raw material powder of the additively manufactured product (preferably a material that does not affect the reuse of the raw material powder), or may be formed by a method different from that of the additively manufactured product P (for example, compression molding, etc.). ) may be manufactured.

The destruction means 40 is composed of, for example, a plurality of pins 41 that can be raised and lowered (see FIG. 2). Each pin 41 is arranged directly below the closing member 14, respectively. The destruction means 40 is raised and lowered by a driving means such as an electric cylinder.

Hereinafter, a procedure for forming a layered product (for example, a core of a cast product) using the layered layer manufacturing apparatus described above will be described. Laminated manufactured products are manufactured through a modeling process, a discharge process, and a cleaning process.

[Modeling process]
In the modeling process, raw material powder is first put into the recoater 20 . As the raw material powder, known materials applicable to additive manufacturing can be used, such as foundry sand, resin powder, ceramic powder, glass powder, metal powder, etc. In this embodiment, foundry sand is used, and specifically, raw material powder (foundry sand) is produced by putting sand and an acid catalyst into the recoater 20 and mixing them. As the sand, for example, natural silica sand or artificial sand can be used. Examples of acid catalysts include aliphatic sulfonic acids (for example, methanesulfonic acid, ethanesulfonic acid, etc.), aromatic sulfonic acids (for example, benzenesulfonic acid, p-toluenesulfonic acid, xylene sulfonic acid, etc.), inorganic acids (for example, , sulfuric acid, phosphoric acid, hydrochloric acid, etc.), carboxylic acids (for example, maleic acid, oxalic acid, etc.), etc. can be used. Acid catalysts can be used alone or in combination of two or more types.

Then, as shown in FIGS. 4 and 5, while horizontally moving the recoater 20 above the modeling box 10, raw material powder is supplied from the recoater 20 onto the modeling table 11 to form a raw material powder layer M of a predetermined thickness. Form. Specifically, the raw material powder is supplied onto the modeling table 11, and the upper surface of the raw material powder is rubbed off with a cutting member (not shown) provided on the recoater 20, so that the upper surface of the raw material powder layer M becomes flat. . Thereafter, if necessary, the same steps as above are repeated to further laminate the raw material powder layer M.

When a predetermined number of raw material powder layers M are stacked on the modeling table 11, as shown in FIGS. 6 and 7, while the binder supply unit 30 is horizontally moved above the modeling box 10, A binder is supplied to a predetermined region of the raw material powder layer M on 11. As the binder, for example, furan resin, phenol resin, epoxy resin, silicone resin, resol type phenol resin, etc. can be used, and in this embodiment, furan resin is used. The chemical reaction between this furan resin and the acid catalyst mixed with the raw material powder causes the particles of the raw material powder (sand) to be bonded to each other. As a result, a solidified region P0 in which the raw material powder is solidified is formed in a predetermined region of the uppermost raw material powder layer M. In the raw material powder layer M, regions other than the solidified region P0 remain as unsolidified powder M'.

Thereafter, as shown in FIG. 8, the modeling table 11 is lowered slightly, and the raw material powder is supplied from the recoater 20 while horizontally moving the recoater 20 above the modeling box 10, and the raw material powder is placed on the modeling table 11. Layer M is further laminated. Then, as shown in FIG. 9, while horizontally moving the binder supply unit 30 above the modeling box 10, the binder is supplied from the binder supply unit 30 to a predetermined area of the uppermost raw material powder layer M, and the raw material in the area is The powder is solidified to form a solidified region P0, and this solidified region P0 is combined with the solidified region P0 of the raw material powder layer M adjacent below. By repeating the above steps, a layered product P is formed inside the modeling box 10, as shown in FIG.

[Discharge process]
Next, the unsolidified powder M' in the modeling box 10 is discharged. In this embodiment, unsolidified powder M' is discharged from a hole 13a provided at the bottom of the modeling box 10 (modeling table 11). Specifically, as shown in FIG. 11, the pin 41 of the destroying means 40 is raised and the upper end of the pin 41 pierces the closing member 14 from below, thereby destroying the closing member 14. As a result, the hole 13a of the table body 13 is opened, and the unsolidified powder M' in the modeling box 10 falls through the hole 13a due to its own weight and is collected in the collection box 50 arranged below the modeling box 10. Ru. The recovered unsolidified powder M' is reused as raw material powder to be input into the recoater 20.

[Cleaning process]
Thereafter, as shown in FIG. 12, unsolidified powder M' adhering to the surface of the layered product P is removed inside the modeling box 10. For example, by blowing air from the air nozzle 60 onto the layered product P placed in the modeling box 10, unsolidified powder M' adhering to the surface of the layered product P is blown off and removed. The removed unsolidified powder M' is discharged from the modeling box 10 through the hole 13a of the table body 13 of the modeling table 11, and collected in the collection box 50 (see FIG. 11). The layered product P from which the unsolidified powder M' on the surface has been removed in this way is taken out from the modeling box 10.

In this way, by utilizing the space inside the modeling box 10 as a space for performing the cleaning process of the additively manufactured product P, a separate space for the cleaning process is not required, so that the additive manufacturing equipment can be downsized. It will be planned. In addition, since there is no need to move the additively manufactured product P to a separate cleaning area, the number of man-hours is reduced, and scattering of unsolidified powder M' and damage to the additively manufactured product P due to the movement of the additively manufactured product P are avoided. can. Furthermore, as described above, by discharging the unsolidified powder M' inside the modeling box 10 through the hole 13a in the bottom of the modeling box 10 (the modeling table 11), a cleaning process is performed inside the modeling box 10. space can be easily secured.

The present invention is not limited to the above embodiments. For example, in the above embodiment, the case where the closure member 14 is destroyed with the pin 41 is shown, but the closure member is not limited to this, and the closure member may be destroyed with a drill or the closure member may be destroyed by heating. . Alternatively, instead of destroying the closing member, the hole in the modeling table may be opened and closed by raising and lowering the closing member. Furthermore, in the discharge step, instead of discharging the unsolidified powder M' from the hole 13a at the bottom of the modeling box 10, the unsolidified powder M' inside the modeling box 10 may be sucked, for example, by a suction means.

Further, in the above embodiment, a case is shown in which an additively manufactured product is formed by solidifying the raw material powder with a binder, but the invention is not limited to this, and the additively manufactured product is formed by solidifying the raw material powder with other means such as a laser. It may also be used to form products.

10 Modeling box 11 Modeling table 12 Side wall 13 Table main body 13a Hole 14 Closing member 14a Solidified layer 20 Recoater (raw material powder supply section)
30 Binder supply section (solidification section)
40 Destruction means 41 Pin 50 Collection box 60 Air nozzle M Raw material powder layer M' Unsolidified powder P Additively manufactured product P0 Solidified area

Claims (1)

a modeling step of forming a layered product by solidifying a predetermined area of the layer of raw material powder each time the layer of raw material powder is laminated in a modeling box; After that, a discharge step of discharging unsolidified raw material powder from the modeling box while the additively manufactured product is housed in the modeling box without raising or lowering the product, and a discharge step of discharging the raw material powder that has not been solidified from the manufacturing box; Equipped with a cleaning process to remove raw material powder adhering to the surface ,
The modeling box has a hole provided at the bottom and a closing member that closes the hole,
The closing member has a solidified layer formed on the surface by solidifying raw material powder, and unsolidified raw material powder sealed inside the solidified layer,
The additive manufacturing method includes, in the discharge step, discharging unsolidified raw material powder from the hole of the modeling box by destroying the closing member .

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