JP7746949B2 - Layered manufacturing device and method for manufacturing layered object - Google Patents

Description

This invention relates to additive manufacturing using fused deposition modeling (FDM), and in particular to stacking layers of fluid resin with flat cross-sections one by one.

Fused deposition modeling (FDM) is one of the additive manufacturing methods also known as 3D printing. Examples of FDM methods that are particularly suitable for producing large objects include those described in Patent Documents 1 and 2.

The upper part of Figure 1 is a side view of the additive manufacturing device 90 used in this additive manufacturing method. In the additive manufacturing device 90, the nozzle Nz scans from left to right on the drawing above the base plate Bp. The lower part is a cross-sectional view seen from behind the direction of travel of the nozzle Nz. Fluid resin Fr with a circular cross section is ejected from the nozzle Nz onto the base plate Bp along a predetermined path.

As shown in Figure 1, fluid resin Fr placed on a base plate Bp is pressed against the base plate Bp by a compression roller 91 that rolls after the nozzle Nz. The compression roller 91 acts as a rolling pin, causing the fluid resin Fr to become a flat bead 92. The flat bead 92 is layered on top of a flat bead 93 that was already layered below it. The pressure of the compression roller 91 bonds the bottom surface of bead 92 and the top surface of bead 93 together in the vertical direction. Beads are also connected horizontally as needed. This completes a three-dimensional shape.

The above additive manufacturing method allows for the supply of more fluid resin per scanning distance, shortening the nozzle's scanning path over the base plate. This therefore shortens the time it takes to complete the model, making it particularly advantageous when creating large models. This method also reduces the proportion of gaps between beads within the model. Furthermore, applying pressure to the beads with a roller allows for stronger bonds between the beads.

Patent Document 3 describes another additive manufacturing method. In this additive manufacturing method, the resin filament deviates from the nozzle's travel path at the bend in the path (paragraph [0057] and Figure 8(b) of Patent Document 3). Because the filament contains carbon fiber and therefore has tension, the nozzle drags the filament when changing direction at the bend. Therefore, a pressure roller is used to press the filament at the bend, ensuring that the filament adheres along the travel path (paragraph [0058] and Figure 8(a) of Patent Document 3).

US Patent Application Publication No. 2018/236723 U.S. Patent No. 10,105,894 International Publication No. 2017/150186

In the additive manufacturing method of Patent Document 3, which uses a tensioned filament, a pressure roller prevents misalignment between the nozzle path and the bead trajectory. However, the inventors discovered that in the methods of creating flat beads from fluid resin using a compression roller, as shown in Patent Documents 1 and 2, the compression roller itself causes misalignment between the nozzle path and the bead. In one aspect, the present invention provides a means for reducing this misalignment.

[1] a base plate;
a nozzle that is scanned along a predetermined path on the base plate and that dispenses fluid resin onto the base plate;
a compression roller that rolls after the nozzle, winding the fluid resin while feeding it toward the base plate and pressing the fluid resin toward the base plate to form a bead having a flat cross section, and when the nozzle changes direction on the path, the compression roller also changes direction so as to roll in the direction of travel of the nozzle;
When viewed in a plane, the compression roller and the discharge port of the nozzle overlap each other.
Additive manufacturing equipment.

[2] In the height direction, the entire compression roller is located below the discharge port of the nozzle,
the compression roller captures the fluid resin on its front surface;
a width g1 of a gap between the discharge port of the nozzle and the upper end of the compression roller in a height direction is equal to or less than half a diameter D of the discharge port of the nozzle;
The diameter d1 of the compression roller is equal to or less than the diameter D of the outlet of the nozzle;
The additive manufacturing apparatus according to [1].

[3] The nozzle further includes a guide roller located between the nozzle and the compression roller in the height direction and in front of the discharge port of the nozzle in the front-rear direction,
The guide roller rolls on the spot in a direction opposite to the rolling direction of the compression roller to guide the fluid resin to the front of the nozzle, and then releases the fluid resin when the compression roller sends the fluid resin toward the base plate;
When the direction of the compression roller is changed, the compression roller and the guide roller rotate horizontally around the discharge port while maintaining their parallelism.
The additive manufacturing apparatus according to [1] or [2].

[4] The diameter d2 of the guide roller is equal to the diameter d1 of the compression roller;
The width g2 of the gap between the guide roller and the compression roller is equal to or greater than the diameter D of the discharge outlet.
The additive manufacturing apparatus according to [3].

[5] Scanning the nozzle along a predetermined path on the base plate and discharging fluid resin from the nozzle;
The fluid resin is wound around a compression roller that rolls after the nozzle and fed toward the base plate, and the fluid resin is pressed against the base plate to form a bead having a flat cross section;
When changing direction on the path, the direction of the compression roller is changed so that the compression roller rolls in the direction of travel of the path.
A method for manufacturing a layered object, comprising:
When changing the direction of the compression roller, the compression roller is rotated horizontally around the outlet of the nozzle while the compression roller and the outlet of the nozzle are overlapped in a plan view.
A method for manufacturing additively manufactured objects.

In one aspect, the present invention provides a means for reducing misalignment between the nozzle path and the bead.

A side view of an additive manufacturing device and a cross-sectional view of a manufactured object A side view of an additive manufacturing device and a cross-sectional view of a manufactured object Top view of the compression roller Plan view of the bead Bottom view of the nozzle and compression roller

<Nozzle and compression roller>

The upper part of Figure 2 is a side view of the additive manufacturing device 10. The additive manufacturing device 10 is equipped with a nozzle Nz. The nozzle Nz is scanned over the base plate Bp. In the drawing, it scans from left to right. The nozzle Nz ejects fluid resin Fr having a circular cross section from a circular outlet Op along a predetermined path onto the base plate Bp. The fluid resin Fr is thermoplastic. The lower part of Figure 2 is a cross-sectional view of the molded object as seen from behind the direction of travel of the nozzle Nz.

The fluid resin Fr shown in Figure 2 can be supplied in a variety of ways. In one embodiment, it is continuously produced from resin pellets using a heating cylinder and extrusion screw (not shown). The continuously produced fluid resin Fr is continuously supplied onto the base plate Bp through a nozzle Nz. This method is more efficient than methods using pre-filamented resin, as it allows beads to be produced directly from resin pellets.

As shown in FIG. 2, the additive manufacturing device 10 includes a compression roller 11. Optionally, the additive manufacturing device 10 includes a guide roller 16. The compression roller 11 rolls on the base plate Bp, following the nozzle Nz. The compression roller 11 may rotate freely or may be forcibly rotated by a motor (not shown). The compression roller 11 captures the fluid resin Fr on its front surface. The compression roller 11 then wraps the fluid resin Fr around itself while feeding it toward the base plate Bp.

Note that the compression roller 91 shown in Figure 1 does not operate like the compression roller 11 shown in Figure 2. Although the fluid resin Fr descends toward the base plate Bp due to gravity, the compression roller 91 does not capture the fluid resin Fr as it descends.

As shown in Figure 2, the compression roller 11 presses the fluid resin Fr against the base plate Bp. The compression roller 11 acts as a rolling pin, forming a bead 12 with a flat cross section from the fluid resin Fr, which has a round cross section. The flat bead 12 is layered on top of a flat bead 13 that was already layered below it. The pressure of the compression roller 11 bonds the bottom surface of the bead 12 with the top surface of the bead 13 in the vertical direction. If necessary, beads are also connected horizontally, such as between bead 13 and bead 17. After completing the scan to form the layer of bead 12, the nozzle Nz and compression roller 11 are raised one level and the next layer is scanned. This series of steps is repeated to obtain a three-dimensional object. The surface of the resulting three-dimensional object may be cut as needed to obtain a surface with the desired shape.

When comparing the additive manufacturing device 10 shown in Figure 2 with a typical FDM-type additive manufacturing device that uses a thin filament, the following advantages are found. First, the additive manufacturing device 10 can supply more fluid resin Fr per scanning distance of the nozzle Nz. Therefore, the scanning path of the nozzle Nz over the base plate Bp is shorter. This shortens the time required to complete the model, making the use of the additive manufacturing device 10 particularly advantageous when producing large models. Furthermore, the use of the additive manufacturing device 10 can reduce the proportion of gaps between beads within the model. Furthermore, the use of the additive manufacturing device 10 can apply pressure to the beads using the compression roller 11, thereby strongly bonding the beads together.

The top of Figure 3 is a plan view of the compression roller 11 shown in the top of Figure 2. The bottom is a plan view of the compression roller 91 (Figure 1) for comparison. When viewed in plan, the compression roller 11 overlaps with the nozzle outlet Op. In other words, there is a small offset between the compression roller 11 and the nozzle outlet Op. In one embodiment, the compression roller 11 rolls on the path Rt of the nozzle outlet Op in this state.

On the other hand, as shown in the lower part of Figure 3, when the compression roller 91 is viewed in plan, the compression roller 11 does not overlap with the nozzle outlet Op. In other words, there is a large offset between the compression roller 91 and the nozzle outlet Op.

As shown in the upper part of Figure 3, the compression roller 11 spreads the fluid resin Fr, giving it a flat cross section. Spreading the fluid resin Fr is done at the same time as sending the fluid resin Fr onto the base plate. However, because Figures 2 and 3 are schematic, they do not definitively show the point on the compression roller 11 at which the fluid resin Fr acquires the flat shape of a bead 12. At least after the compression roller 11 has passed, the fluid resin Fr has changed into a flat bead 12.

As shown in the lower part of Figure 3, the compression roller 91 also spreads the fluid resin Fr in a similar manner. Both the compression roller 11 and the compression roller 91 spread the fluid resin Fr symmetrically about the center line of the path Rt of the nozzle discharge port Op. The characteristic of the lower part is that after the fluid resin Fr lands on the base plate, the compression roller 91 spreads the fluid resin Fr after the nozzle discharge port Op leaves that location.

As shown in the upper part of Figure 3, the nozzle outlet Op changes direction on the path Rt. In the figure, the change of direction is approximately 60 degrees, but this is an example. The angle of the change of direction is not limited. For example, a 180-degree turn, a so-called hairpin turn, is also included in the change of direction. However, going back directly above the path that has been followed is not included in the change of direction. The curvature of the path Rt when changing direction is also not limited. Drawing a gentle curve is also included in the change of direction. The curvature may change during the change of direction. Turning alternately left and right, with each turn being included in the change of direction.

As shown in the upper part of Figure 3, when changing direction, the discharge port Op changes its direction of travel. Because the discharge port Op is circular, it does not need to rotate horizontally itself, and in the new direction it supplies fluid resin Fr with the same cross-sectional shape as before the change in direction.

As shown in the upper part of Figure 3, when the nozzle outlet Op changes direction, the compression roller 11 also changes direction so that it rolls in the new direction of the nozzle outlet Op. The compression roller 11 rotates horizontally around the outlet Op as its axis. A feature of this embodiment is that at this time, the compression roller 11 and the nozzle outlet Op remain overlapped in a planar view. The compression roller 11 may rotate freely horizontally, or may be forcibly rotated by a motor (not shown).

The direction change and horizontal rotation of the compression roller 91 shown in the lower part of Figure 3 will be explained in Figure 4.

<Direction changes and bead shape>

The top row of Figure 4 shows the bead 12 (Figure 2) in plan view. The bottom row shows the bead 92 (Figure 1) in plan view. Ideally, the bead 92 should be compressed by the compression roller 91 up to the point where the discharge port Op changes direction. However, when the direction of travel of the discharge port Op changes, the compression roller 91 also changes direction. Therefore, the compression roller 91, which has already changed direction, collides sideways with the resin discharged in the shaded area near the point where the discharge port Op changes direction. Because the compression roller 91 stretches the fluid resin sideways, the shape of the bead 92 is distorted where the path Rt changes course. The shape of the bead 92 is no longer symmetrical along the path Rt of the discharge port Op. As a result, a discrepancy occurs between the specified nozzle path and the formed bead.

In contrast, the bead 12 in the top plan view of Figure 4 is compressed by the compression roller 11 up to the point where the discharge port Op changes direction. At the point where the discharge port Op changes direction, the compression roller 11 also changes direction. This prevents the fluid resin discharged near the point where the discharge port Op changes direction from being stretched sideways. As a result, the shape of the bead 12 is less likely to collapse, even near the point where the path Rt changes course. The shape of the bead 12 is symmetrical, or closer to symmetrical, along the path Rt of the discharge port Op. In this way, the deviation between the determined nozzle path and the formed bead is reduced.

<Size and position of compression roller>

Returning to Figure 2, the entire compression roller 11 may be positioned below the outlet Op of the nozzle Nz in the height direction in order to overlap the compression roller 11 and the nozzle outlet Op. In this case, there is a gap with a width _g1 between the outlet Op and the upper end of the compression roller 11. The width _g1 of the gap is preferably less than half the diameter D of the outlet Op. This is advantageous for sending the fluid resin Fr onto the base plate Bp without meandering. By allowing the fluid resin Fr to flow over the compression roller 11 without meandering, the shape of the bead 12 is prevented from becoming distorted.

In one embodiment shown in Figure 3, the axis of the compression roller 11 in plan view is in contact with the rear end of the nozzle outlet Op. Referring to Figure 2, in other words, the entire front half of the compression roller 11 is located below the outlet Op of the nozzle Nz in side view. In another embodiment, the axis of the compression roller 11 is located further rearward than the rear end of the outlet Op of the nozzle Nz. In other words, only a portion of the front side of the compression roller 11 is located below the outlet Op of the nozzle Nz.

In Figures 2 and 3, if the axis of the compression roller 11 is positioned further forward than the rear end of the nozzle's discharge port Op, the fluid resin Fr may tend to flow toward the rear of the compression roller 11. For this reason, the positional relationship between the compression roller 11 and the nozzle Nz's discharge port Op described above is advantageous for the fluid resin Fr to flow in front of the compression roller 11.

₂ is preferably equal to or smaller than the diameter D of the discharge port Op. This reduces the meandering of the fluid resin Fr between the compression roller 11 and the discharge port Op and between the compression roller 11 and the base plate Bp, which is advantageous in suppressing distortion of the shape of the bead 12.

<Addition of guide rollers>

The guide roller 16 shown in Figure 2 is located between the nozzle Nz and the compression roller 11 in the height direction. The guide roller 16 is also located in front of the outlet Op of the nozzle Nz in the forward and backward direction of the nozzle Nz's movement. Preferably, the entire guide roller 16 is located in front of the front end of the outlet Op. The guide roller 16 rolls in place in the opposite direction to the rolling of the compression roller 11. The guide roller 16 may rotate freely or may be forcibly rotated by a motor (not shown).

As shown in the upper part of Figure 2, there is a gap of width _g2 between the guide roller 16 and the compression roller 11. The fluid resin Fr flows through the gap of width _g2 . The guide roller 16 captures the fluid resin Fr and guides it forward of the nozzle Nz by rolling. When the compression roller 11 sends the fluid resin Fr toward the base plate Bp, the guide roller 16 releases the fluid resin Fr.

2, the diameter _d2 of the guide roller 16 is not particularly limited. The diameter _d2 may be equal to the diameter _d1 of the compression roller 11, for example.

In the additive manufacturing device 10 shown in Figure 2, the gap width _g2 is preferably equal to or greater than the diameter D of the discharge port Op. When the gap width _g2 is equal to or greater than the diameter D and is an appropriate width, the meandering of the fluid resin Fr between the compression roller 11 and the guide roller 16 can be reduced, which is advantageous for suppressing distortion of the shape of the bead 12. Conversely, when the gap width _g2 is less than the diameter D, the flow resistance between the compression roller 11 and the guide roller 16 is large, and it may be difficult for the fluid resin Fr to enter the gap.

As shown in the upper part of Figure 2, there is a height difference _g3 between the lower end of the guide roller 16 and the lower end of the compression roller 11. This difference _g3 is preferably greater than 0. That is, it is preferable that the lower end of the guide roller 16 is located higher than the lower end of the compression roller 11. This prevents the guide roller 16 from colliding with the bead 17 when forming the bead 13 so that the bead 13 is lined up next to the previously formed bead 17, as shown in the lower part of Figure 2.

Figure 5 shows a bottom view of an additive manufacturing apparatus 10 according to one embodiment. The additive manufacturing apparatus 10 further includes a base 15, bearing 14, and bearing 19, which are components not shown in Figure 2. Bearing 14 and bearing 19 are located on the bottom surface of base 15, i.e., the front side of the page. Bearing 14 connects compression roller 11 to base 15. Bearing 19 connects guide roller 16 to base 15. These bearings support each roller, for example, with bearings.

The bearing 14 shown in Figure 5 causes the compression roller 11 to roll forward, i.e., toward the right side of the page, around a horizontal axis. The bearing 14 may also be able to cause the compression roller 11 to roll in the opposite direction. The bearing 19 causes the guide roller 16 to roll backward, i.e., toward the left side of the page, around a horizontal axis. However, the guide roller 16 does not roll on the base plate Bp, but simply spins freely in place. The bearing 19 may also be able to cause the guide roller 16 to roll in the opposite direction. The guide roller 16 and the compression roller 11 are parallel. The rolling axis of the guide roller 16 and the rolling axis of the compression roller 11 are parallel.

In one embodiment shown in Figure 5, the base 15 is configured as a ring-shaped table that rotates horizontally around the outlet Op. The shape of the base 15 is not limited to this. The base 15 may rotate freely horizontally, or may be forcibly rotated by a motor (not shown). Because the compression roller 11 is attached to the base 15, the compression roller 11 also rotates horizontally around the outlet Op. The base 15 maintains a state in which the compression roller 11 and the outlet Op of the nozzle Nz overlap when viewed from above or below. Because the guide roller 16 is attached to the base 15, the guide roller 16 also rotates horizontally around the outlet Op. The base 15 maintains the parallelism between the guide roller 16 and the compression roller 11. The guide roller 16 and the compression roller 11 rotate horizontally while maintaining their parallelism.

10 Additive manufacturing device, 11 Compression roller, 12-13 Bead, 14 Bearing, 15 Base, 16 Guide roller, 17 Bead, 19 Bearing, 90 Additive manufacturing device, 91 Compression roller, 92-93 Bead, Bp Base plate, D Diameter of outlet, _d1 Diameter of compression roller, _d2 Diameter of guide roller, Fr Fluid resin, _g1 Gap width, _g2 Gap width, _g3 Height difference, Nz Nozzle, Op Outlet, Rt Path

Claims (4)

a base plate;
a nozzle that is scanned along a predetermined path on the base plate and that dispenses fluid resin onto the base plate;
a compression roller that rolls after the nozzle, winding the fluid resin while feeding it toward the base plate and pressing the fluid resin toward the base plate to form a bead having a flat cross section, and when the nozzle changes direction on the path, the compression roller also changes direction so as to roll in the direction of travel of the nozzle;
When viewed in a plane, the compression roller and the discharge port of the nozzle overlap each other,
In the height direction, the entire compression roller is located below the discharge port of the nozzle,
the compression roller captures the fluid resin on its front surface;
The width _g1 of the gap between the outlet of the nozzle and the upper end of the compression roller in the height direction is equal to or less than half the diameter D of the outlet of the nozzle,
The diameter _d1 of the compression roller is equal to or less than the diameter D of the outlet of the nozzle;
Additive manufacturing equipment. a guide roller located between the nozzle and the compression roller in the height direction and in front of the outlet of the nozzle in the front-rear direction;
The guide roller rolls on the spot in a direction opposite to the rolling direction of the compression roller to guide the fluid resin to the front of the nozzle, and then releases the fluid resin when the compression roller sends the fluid resin toward the base plate;
When the direction of the compression roller is changed, the compression roller and the guide roller rotate horizontally around the discharge port while maintaining their parallelism.
The additive manufacturing apparatus according to claim 1 . The width _g2 of the gap between the guide roller and the compression roller is equal to or greater than the diameter D of the discharge port,
The lower end of the guide roller is located higher than the lower end of the guide roller.
The additive manufacturing apparatus according to claim 2 . The nozzle is scanned along a predetermined path on the base plate, and fluid resin is discharged from the nozzle.
The fluid resin is wound around a compression roller that rolls after the nozzle and fed toward the base plate, and the fluid resin is pressed against the base plate to form a bead having a flat cross section;
When changing direction on the path, the compression roller is changed direction so as to roll in the direction of travel of the path;
A method for manufacturing a layered object , wherein when changing the direction of the compression roller, the compression roller is rotated horizontally around an axis of the discharge port while the compression roller and the discharge port of the nozzle remain overlapped in a plan view ,
In the height direction, the entire compression roller is located below the discharge port of the nozzle,
the compression roller captures the fluid resin on its front surface;
The width _g1 of the gap between the outlet of the nozzle and the upper end of the compression roller in the height direction is equal to or less than half the diameter D of the outlet of the nozzle,
The diameter _d1 of the compression roller is equal to or less than the diameter D of the outlet of the nozzle;
A method for manufacturing additively manufactured objects.