NL2025393B1

NL2025393B1 - Ergonomic break-away support

Info

Publication number: NL2025393B1
Application number: NL2025393A
Authority: NL
Inventors: Alexander Van Den Berg Menno
Original assignee: Ultimaker Bv
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2021-10-28

Abstract

A method ofdesigning a break-away support structure for a 3D object is described. The method comprises the receiving design information for the 3D object, the locating overhangs in the 3D object that need support during manufacturing by an additive manufacturing device, and the designing of a support structure arranged to support critical areas of the overhangs that fulfil an overhang criterium. The method further comprises the designing at least one hole in the support structure with a minimal diameter. In an embodiment the diameter is at least 2 cm, for insertion of a human finger so that the support can be removed manually.

Description

Ergonomic break-away support Field of the invention The present invention relates to a computer implemented method of designing a break- away support structure for a 3D object. The invention also relates to a computer program product for performing the method of designing, and to a method of additive manufacturing a 3D object. Background art Fused filament fabrication (FFF) is a 3D printing process that uses a continuous filament of a thermoplastic material. Filament is fed from a filament supply through a moving, heated print head, and is deposited through a print nozzle on a build plate. The print head may be moved relative to the build plate under computer control to define a printed shape. In certain FFF devices, the print head moves in two dimensions to deposit one horizontal plane, or layer, at a time. The work or the print head is then moved vertically by a small amount to begin a new layer. Next to FFF, other types of additive manufacturing are known such as Stereolithography (SLA), Digital Light Processing (DLP), Selective Laser Sintering (SLS), Selective Laser Melting (SLM), Electronic Beam Melting (EBM), Laminated Object Manufacturing (LOM), Binder Jetting (BJ) and Material Jetting (MJ). In many of the above-mentioned additive manufacturing technologies, objects can be manufactured using support material for supporting certain parts of the 3D object during manufacturing. Once the manufacturing process is finished, the 3D object together with the attached support material can be removed from the manufacturing device. Next, the support material is removed from the 3D object. There are two main types of support material. Both have their advantages and disadvantages. The first one is support material soluble in a liquid, such as in water. This type of support material can be removed by washing the 3D object so as to remove the soluble material. The second type is the so-called break-away support. This type of support needs to be removed by literally breaking away the support from the 3D object. Breaking away depends on the application and also the strength of the material. Breaking away is often done using tools such as nippers and pliers. Often people use their hands to manually break away the support. This may work, but very often a user cannot predict what part exactly will be removed when applying a manual force onto the support. Manual removal may result in damaging the object, or only partly removal of the support, or it can possibly lead to unwanted injuries. Summary of the invention The aim of the present invention is to provide a solution for the problem of how to remove break-away support in a controlled and user-friendly way.

According to a first aspect of the present invention, there is provided a computer implemented method of designing a break-away support structure for a 3D object, the method comprising: 40 - receiving design information for the 3D object;

- locating overhangs in the 3D object that need support during manufacturing by an additive manufacturing device; - designing a support structure arranged to support critical areas of the overhangs that fulfil an overhang criterium; - designing at least one hole in the support structure.

In an embodiment, the method comprises: - dividing the support structure into multiple segments by inserting break zones in the support structure; - selecting target segments being those segments that have sufficient space for designing a hole; - designing one or more holes in each of the target segments.

By inserting break zones in the support structure to create multiple segments, the support structure can be divided into segments that can be optimized in size, shape and position so as to facilitate the removal.

The hole designed may be a through hole through the support structure. Using through holes provide for the opportunity to hook in special tooling that can be pulled at with sufficient force.

In an embodiment, the at least one has a minimal diameter of at least 2 cm, for insertion of a human finger. Using sufficiently large diameters, the segments or hole structure can be removed manually by sticking in a finger and pull at the structure. It is then not required to have any extra external tooling.

The at least one hole comprises a curved channel. Curved channels are preferred in situations wherein e.g. an index finger is used to get a grip onto the support structure and/or its segments.

In an embodiment, the at least one hole is surrounded by a channel wall, and wherein the support structure comprises reinforcement structures connecting the channel wall to an outer wall of the support structure. Creating a wall around the channel will not only properly define the channel, but it will provide for internal strength within the segment(s). Furthermore, the wall of the channel can be connected to other walls of the segments so that pulling forces applied onto the channel will be forwarded onto the other wall. This will decrease the risk of having a segment itself get broken in multiple parts, and each segment can be removed in one piece.

In an embodiment, the support structure comprises an infill structure with an infill percentage of at least 20 %.

Such values have shown to be advantages when using infill within the support structure. A lower infill percentage is possible, but the risk of breaking the structure in an uncontrolled way will increase.

In an embodiment, designing a support structure arranged to support those critical areas of the overhangs that fulfil the overhang criterium, comprises:

- project each of those critical areas onto an associated underlying surface, to obtain area projections; - design a support platform underneath each of the critical areas; - design side walls between a peripheral of each of the support platforms and a peripheral of the associated area projections, wherein the at least one hole is designed in the side walls.

In this way 3D columns are created that support the critical areas. The 3D columns contain outer vertical walls that, if sufficiently large, can be used to design holes in, which can be used to hold on to for removal of the support structure.

In an embodiment, the at least one hole has a circular or oval shaped circumference. Such shapes will provide for more strength and in case the structure is removed by hand, such shapes are preferred for ergonomic reasons. Rounded shapes are more comfortable for a human finger and hand especially when some force is applied onto it.

The above described method can be executed by means of a software program, such as a slicing program. In an embodiment, the designing the at least one hole in the support structure comprises receiving instructions from a user, and designing one or more holes into the support structure depending on the instructions from the user. In this embodiment, the user can instruct the program on how and where to position the holes. The program may be arranged to first design the hole(s) and the give the user the opportunity to adjust the hole(s) and/or create (i.e. design) further holes and/or remove suggested holes.

According to a further aspect, there is provided a computer program product comprising code embodied on computer-readable storage and configured so as when run on one or more processing units to perform the method according to any one of the preceding claims. The computer program product may comprise a slicing program such as Ultimaker CURA ®.

According to a further aspect, there is provided a method of additive manufacturing a 3D object, the method comprising building the 3D object using an additive manufacturing device, wherein a break-away support structure is created to support those area of overhangs in the 3D object that fulfil an overhang criterium, and wherein the support structure comprises at least one hole.

Brief description of the drawings These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. In the drawings, Figure 1 shows a 3D object which serves as an example of an 3D object to be printed using a method according to an embodiment of the invention; Figure 2 shows an example of the 3D object of Figure 1 in combination with a support structure; Figure 3 schematically shows a perspective view of the 3D object of Figure 1 being supported by a different break-away support structure;

Figure 4 schematically shows a perspective view of the embodiment of Figures 3 and a hand of a user trying to pull off one of the segments; Figure 5 schematically shows a perspective view of the embodiment of Figures 3 and 4 but now with the segment manually pulled off by the user; Figure 6 shows the configuration of Figure 5 but now with the index finger of the user pulling at the second segment; Figure 7 shows the 3D object of Figure 3, with the object freed from support material, Figure 8 shows a horizontal cross section of the segment of the embodiment shown in Figure 7; Figure 9 shows a horizontal cross section of the segment of Figure 7, but now with specific reinforcement structures inside; Figure 10 schematically shows a side view of a 3D object that is supported by a support structures designed by a method according to an embodiment of the invention; Figure 11 shows perspective views of two break-away segments after removal from the 3D object of Figure 10; Figure 12 shows the 3D object and parts of the support structure after removal of most of the break-away segments; Figure 13 shows perspective views of two break-away segments after removal from the 3D object of Figure 12; Figure 14 schematically shows an example of an FFF device, also referred to as the 3D printer; Figure 15 schematically shows an example of a computing device according to an embodiment, and Figure 16 shows a flow chart of a method of designing a break-away support structure for a 3D object, according to an embodiment of the invention.

It should be noted that items which have the same reference numbers in different Figures, have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item has been explained, there is no necessity for repeated explanation thereof in the detailed description. Detailed description of embodiments Figure 1 shows a 3D object 1 which serves as an example of an 3D object to be printed using a method according to an embodiment of the invention. In this example, the 3D object is a wine glass 1, which comprises a foot 2, a stem 3 and a goblet 4. In order to be able to manufacture the glass 1 using an additive manufacturing device, the design needs to be transformed into instructions for the manufacturing device. Whether the wine glass 1 will be manufactured out of real glass or out of any other material, such as a thermoplastic polymer, is not relevant for discussing the present invention.

The 3D design of the wine glass 1 can be processed in a computer which runs a so-called slicing program configured to transform the 3D object date into print instructions for the additive manufacturing device.

Such a slicing program is configured to slice up the 3B object in multiple slices and determine for each slice how is can be printed using print paths.

In some 3D 5 manufacturing technologies, such as fused filament fabrication, certain parts of an object may need support for an optimal printing result.

Such support can be printed along with printing the object itself.

Most slicing programs can add support structures to the 3D model.

Support structures are added at those parts that, without support, will most probably not get printed properly.

Figure 2 shows an example of the 3D object 1 of Figure 1 in combination with a support structure 21 arranged to support an area of the overhang 5 of the 3D object 1, see also Figure 1. In this example, the stem 3 of the wine glass 1 is surrounded by a support structure 8 which supports the goblet 4. The support structure 8 comprises a cylindrical shaped outer wall and can be made by using well known slicing algorithms.

Today's slicing programs use an overhang criterium and support structures are arranged so as to support only critical areas of the overhangs that fulfil a certain overhang criterium.

An example of an overhang criterium is to check if a surface makes an angle with the horizontal that is smaller than a critical angle.

For example, if certain areas of the outer surface of the goblet 4 in Figure 1 are horizontal, or nearly horizontal, then those areas need support.

Once the angle between the outer surface and the horizontal exceeds a critical angle, there is no need for support any longer.

In the example of Figure 2, the critical angle has been set to about 60°. As a result, nearly the whole under surface of this goblet 4 is supported.

If a smaller critical angle would have been chosen, such as 40°, the support structure 8 in Figure 2 would have been a thinner cylinder.

Figure 3 schematically shows a perspective view of the 3D object 1 of Figure 1 being supported by a different break-away support structure designed using a method of designing according to an embodiment of the present invention.

As in the known methods, overhangs in the 3D object are located that need support during manufacturing by an additive manufacturing device, and then a support structure is designed that is arranged to support critical areas of the overhangs that fulfil an overhang criterium.

In this example, the support structure is divided into two segments 31, 32 by inserting a break zone 30 in the support structure.

In each of the two segments holes 34, 35 are designed having a minimal diameter d.

In this embodiment, the minimal diameter d is at least 2 cm so that a human finger can be inserted.

This is shown in Figure 4. In this embodiment shown in Figure 3 and 4, the holes 34 and 35 in each segment are connected to form one channel, through which a user 40 can put his index finger in a curved way.

In that way, the user 40 can easily apply a force, so as to pull the segments away from the stem 3, as is shown in Figure 5. Figure 5 schematically shows a perspective view of the embodiment of Figures 3 and 4 but now with the segment 31 manually pulled off by the user 40. Once the first segment of support has been removed, the user can manually remove the second segment 32 following the same procedure.

It should be clear to the skilled reader that normally the user will use both hands at the same time to remove the segments, i.e. one hand to hold the 3D object and the support still attached, and the other hand to break away one of the support segment 31, 32.

Figure 6 shows the configuration of Figure 5 but now with the index finger of the user 40 pulling at the second segment 32. Once the second segment 32 is also removed from the 3D object 1, the object 1 is free from support material as is shown in Figure 7. As can be seen from the segment 32 in Figure 7, the segment 32 comprises two flat walls 71, 72 which are separated by a gap 73. The segment 32 also comprises a curved surface 74 which function is to support the goblet 4. Preferably, the segment 32 is designed in such a way that, before removal, it is only in contact with the goblet 4 and the other segment 31. As can be seen from Figure 6, the segment 32 is not supported by the foot 2 and is standing on the ground next to the foot 2. An advantage of this design is that the segments 31, 32 can be removed without creating any forces onto the foot 2 or on the stem 3.

Figure 8 shows a horizontal cross section of the segment 31 of the embodiment shown in Figure 7. In this example, the segment comprises a curved channel 81. In its cross section, this channel 81 can have a circular shape, or any other suitable shape, such as the pill-shaped cross section shown in Figure 7, suitable for receiving a finger of a user. The channel 81 could even have a triangular or rectangular cross section, but in order to improve the comfort of the user, the channel 81 preferably has rounded inner walls. It is noted that in this example the channel 81 forms a through hole piercing through part of the segment 31. Instead the channel could be partly filled, so that two recesses are present, both arranged to receive a finger. For example, one of the recesses (i.e. holes) could be used to stick in a thumb, whereas the second recess could be used to stick in an index finger. In that way the user will also be able to manually grab a support segment and remove it in an ergonomic way. In the embodiment of Figure 8, the segment 31 is filled with an infill structure 82. The infill structure 82 in this example has rectangular shapes to fill up the interior of the segment 31. It is appreciated by the skilled person that other infill patterns are possible. Also, a fully 100% infill may be possible. However, this may lead to very long print times. Using too little infill may result in weak support that will break into pieces which is not preferred. In an embodiment, the support structure comprises an infill structure with an infill percentage of at least 20 %. In most cases this percentage will give the break-away support sufficient internal strength so that each of the segments can be broken away in one piece.

In an alternative embodiment, the at least one hole is surrounded by a channel wall, wherein the support structure comprises reinforcement structures connecting the channel wall to an outer wall of the support structure. Figure 9 shows an example of such reinforcement structures, see reinforcements 91, 92. The reinforcement structures in this example comprise direct beams 91 from a channel wall 90 to an outer wall 95 of the support structure 31. Furthermore, other beams 92 having branches are shown that connect the channel wall 90 to the outer wall 95 of the support structure 31. It is noted that the reinforcements 90, 91 may extend along the Z-direction all along the height of the segment 31. Alternatively, the reinforcement structures may be arranged at certain locations within the segment 31. The reinforcement 40 structures may be arranged so as to transfer forces on the outer walls of the support structure

(e.g. the segments 31, 32) that are connected to the 3D object by break lines, onto the walls 90 of the channel/hole 34.

Figure 10 schematically shows a side view of a 3D object 50 that is supported by a support structures designed by a method according to an embodiment of the invention. The object 50 looks like a desk lamp comprising a foot 51, a stem 52 and a head 53. For that reason, the 3D object is also referred to as desk lamp 50. Whether this 3D object 50 could really be a base for a functioning desk lamp, is not relevant here. This example of the desk lamp only serves to explain how support can look like that is made according to embodiments of the invention. In the example of figure 10, the desk lamp 50 is supported by a plurality of break-away segments. A part of the stem 52 is supported by a vertical wall that is divided into a number of wall segments 54, 55, 56, 57, 58 and 59. Only that part of the stem 52 is supported where the angle between the stem and the horizontal exceeds a critical angle. In this case the critical angle is indicated by B. In the example of Figure 10, the critical angle has been set to about 40°. As a result, only a part of the stem 52 is supported. If a larger critical angle would have been chosen, such as 60°, the supporting wall in Figure 10 would have been larger in area.

The wall segments are separated from each other by break lines indicated by dashed lines, see break line 80. The head 53 of the desk lamp is supported by a cylindrical shaped support structure that in this example is divided into two further segments 61, 62 separated by two break lines, only one of which is visible, see beak line 83. In an embodiment, the method of designing comprises selecting target segments being those segments that have sufficient space for designing a hole, and then designing one or more holes in each of the target segments. In Figure 10 the segment 58 does not have enough space to design a hole, so this segment does not have a hole. All the other segments shown in Figure 10 do have a hole designed, see for example hole 65 in segment 54, hole 66 in segment 61, and hole 67 in segment 62. It should be noted that next to the break lines indicated by the dashed lines, further break lines are present between the support structure and the 3D object 50. For example, at the lower rim of the head 53 of the desk lamp 50, a circular break line 68 is arranged.

Figure 11 shows two break-away segments 55, 62 after removal from the 3D object 50 of Figure 10. The segment 55 is a flat rectangular shaped piece of support material having a through hole, and the segment 62 is a semi-cylindrical piece of support material having a through 62. Figure 12 shows the 3D object 50 and parts of the support structure after removal of most of the break-away segments. As can be seen from Figure 12, two more segments 71,72 became visible which are arranged to support a top of the inner wall of the head 53. The segments 71,72 may each comprise one or more holes, one of which is shown in the figure, see hole 74.

Figure 13 shows perspective views of two break-away segments 58, 72 after removal from the 3D object 50 of Figure 12. The segment 58 is a flat triangular shaped piece of support material, and the segment 72 is a semi-cylindrical piece of support material having a flat wall 75 resulting from the break line between the segments 71 and 72. through 62. The semi-cylindrical segment 72 comprises a channel 74 arranged to receive a hook 70 that can be handled by the 40 user. The channel 74 may be similar to the channel 81 shown in the embodiments of Figures 6-9 but may have smaller diameter as compared to the holes arranged to receive a human finger. Typical diameters arranged to receive tools may vary between 0.5 cm and 2 cm, but smaller and larger diameters are possible.

Whether support is designed as (curved) walls, or as filled structures may depend on the application and the expected forces when breaking away a certain part of the support structure. For example, the segment 61, 62 are designed as curved walls and the segments 71, 72 are designed as semi-cylindrical shaped filled structures. The segments 71, 72 could have been made using only walls, but since the inner wall of the head 53 requires a support platform, the segments preferably comprise a curved top part, see part 76. This top surface 76 may ask for internal support within the segment 72 itself, and for that reason, the segment 72 is at least partly filled with infill.

The additive manufacturing device used in the method of additive manufacturing may be a fused filament fabrication (FFF) device. Figure 14 schematically shows an example of an FFF device 100, also referred to as the 3D printer 100. The 3D printer 100 comprises a print head 102 also referred to a deposition head 102. At its outer end the print head 102 comprises a nozzle 104 where molten filament can leave the deposition head 102. A filament 105 is fed into the print head 102 by means of a feeder 103. Part of the filament 105 is stored in a filament storage which could be a spool 108 rotatably arranged onto a housing {not shown) of the 3D printer, or rotatably arranged within a container (not shown) containing one or more spools.

The 3D printer 101 comprises a controller 107 arranged to control the feeder 103 and the movement of the print head 102, and thus of the nozzle 104. In this embodiment, the 3D printer further comprises a Bowden tube 109 arranged to guide the filament 105 from the feeder 103 to the print head 102. The 3D printer 100 also comprises a gantry arranged to move the print head 102 at least in one direction, indicated as the X-direction. In this embodiment, the print head 102 is also movable in a Y-direction perpendicular to the X-direction. The gantry comprises at least one mechanical driver 114 and one or more axles 115 and a print head docking unit 116. The print head docking unit 116 holds the print head 102 and for that reason is also called the print head mount 116. It is noted that the print head docking unit 116 may be arranged to hold more than one print head, such as for example two print heads each receiving its own filament.

The feeder 103 is arranged to feed and retract the filament 105 to and from the print head

102. The feeder 103 may be arranged to feed and retract filament at different speeds to be determined by the controller 107.

A build plate 118 may be arranged in or under the 3D printer 100 depending on the type of 3D printer. The build plate 118 may comprise a glass plate or any other object suitable as a 40 substrate. In the example of Figure 14, the build plate 118 is movably arranged relative to the print head 102 in a Z-direction, see Figure 14. Figure 14 shows that the 3D object 1 and its support structure has been built on the build plate 118. Once the 3D object 1 and its support structure have been removed from the built plate 118, the user will be able to manually remove the support structure as was described above with reference to figures 4-7. The controller 107 may be arranged to receive print instructions from another device such as a PC or other computing device. Print instructions can be coded in the G-code format or any other suitable format. The G- code could be created by means of a slicing program running on a computing device.

Figure 15 schematically shows an example of a computing device 120 according to an embodiment. The computing device 120 comprises a processing unit 121, an I/O interface 122 and a memory 123. The processing unit 121 is arranged to read and write data and computer instructions from the memory 123. The processing unit 121 may also be arranged to communicate with sensors and other equipment via the VO interface 122. The computing device 120 may comprise several processing units. The memory 123 may comprise a volatile memory such as ROM, or a non-volatile memory such as a RAM memory, or any other type of computer-readable storage.

The computing device 120 may be arranged to perform the method of designing a break- away support structure for a 3D object, as described above. For that purpose, a computer program product comprising code may be embodied on the computer-readable storage 123 and configured so as when run on one or more processing units to perform the described method.

Figure 16 shows a flow chart of a method 130 of designing a break-away support structure for a 3D object, according to an embodiment of the invention. The method comprises the following: receiving 131 design information for the 3D object, locating 132 overhangs in the 3D object that need support during manufacturing by an additive manufacturing device, designing 133 a support structure arranged to support critical areas of the overhangs that fulfil an overhang criterium, and designing 134 at least one hole in the support.

As mentioned above, the method of designing may be performed by a slicing program running on a computing device such as a PC. The method of designing may also be performed on a computing unit arranged in an additive manufacturing device, such as the 3D printer 100.

The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible and are included in the scope of protection as defined in the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments. The method of additive manufacturing may be performed using other technologies than the described FFF technology. All additive manufacturing techniques that require any sort of 40 support structures during manufacturing could be used to implement the invention. In the claims,

any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CONCLUSIONS

A computer-implemented method (130) for designing a breakaway support structure for a 3D object, the method comprising: - receiving (131) design information for the 3D object (1, 50); locating (132) overhangs in the 3D object that require support during fabrication by an additive fabrication device; - designing (133) a support structure adapted to support critical portions of the overhangs meeting an overhang criterion; - designing (134) at least one hole (34, 35, 65, 66, 67) in the support structure.

Method according to claim 1, wherein the method comprises: - dividing the support structure into several segments by inserting fracture zones in the support structure; - selecting target segments being those segments which have sufficient space for designing a hole therein; - designing one or more holes in each of the target segments.

The method of claim 1 or 2, wherein the hole is a through hole through the support structure.

A method according to any one of the preceding claims, wherein the at least one hole has a minimum diameter of at least 2 cm to accommodate a human finger.

A method according to any one of the preceding claims, wherein the at least one hole comprises a curved channel.

A method according to any one of the preceding claims, wherein the at least one hole is surrounded by a channel wall, and wherein the support structure comprises reinforcement structures connecting the channel wall to an outer wall of the support structure.

A method according to any one of the preceding claims, wherein the support structure comprises a fill structure with a fill percentage of at least 20%.

A method according to any one of the preceding claims, wherein designing a support structure arranged to support those critical areas of the overhangs meeting the overhang criterion comprises: - projecting each of said critical areas onto an associated underlying surface to obtain 40 area projections;

- designing a support platform under each of the critical areas; - designing side walls between an edge of each of the support platforms and an edge of the associated projections, wherein the at least one hole is designed in the side walls.

A method according to any one of the preceding claims, wherein the at least one hole has a circular or oval perimeter.

A method according to any one of the preceding claims, wherein designing the at least one hole in the support structure comprises: - receiving instructions from a user; - designing one or more holes in the support structure depending on the instructions of the user.

A method according to any one of the preceding claims, wherein designing at least one hole in the support structure comprises: - receiving instructions from a user, and - designing one or more holes in the support structure depending on the instructions of the user.

A computer program product comprising code embodied in computer readable storage (123) and configured such that, when executed on one or more processing units (121), the method of any preceding claim is executed.

13. A method of additive manufacturing a 3D object, comprising building the 3D object using an additive manufacturing device, wherein a breakaway support structure is created to support those overhangs in the 3D object that meet to an overhang criterion, and wherein the support structure includes at least one hole.