WO2018192794A1

WO2018192794A1 - Method for manufacturing an object by means of 3d printing

Info

Publication number: WO2018192794A1
Application number: PCT/EP2018/059075
Authority: WO
Inventors: Paulus Albertus VAN HAL; Rifat Ata Mustafa Hikmet
Original assignee: Philips Lighting Holding B.V.
Priority date: 2017-04-20
Filing date: 2018-04-10
Publication date: 2018-10-25

Abstract

A method for manufacturing an object by means of 3D printing is provided. The method uses as printing material an acrylate polymer formed from one or more types of monomers that include at least one of an acrylate monomer and a methacrylate monomer. The method also uses a printer head with a nozzle that is arranged to deposit the printing material, wherein the nozzle has an orifice that comprises a central portion defining a ring of the orifice through which the printing material can be extruded during deposition of the printing material. The method comprises the steps of heating the printing material to a temperature in a range of 200 to 300 degrees Celsius before depositing the printing material, depositing at least a portion of the printing material in the form of a hollow tube having a cylinder shape by extruding the printing material through the ring, and cooling the deposited printing material (105) below its glass transition temperature.

Description

METHOD FOR MANUFACTURING AN OBJECT BY MEANS OF 3D PRINTING

FIELD OF THE INVENTION

The present invention generally relates to the field of 3D printing. More specifically, the present invention relates to a method for producing three-dimensional objects by means of 3D printing, to a 3D-printing apparatus for performing such a method, and to a computer program product comprising instructions which, when the computer program product is executed by the 3D-printing apparatus, cause the 3D-printing apparatus to carry out the method. The invention also relates to an object that is obtainable by the method, and to a lighting arrangement comprising such an object. BACKGROUND OF THE INVENTION

Additive manufacturing, sometimes also referred to as 3D printing, refers to processes used to synthesize a three-dimensional object. 3D printing is rapidly gaining popularity because of its ability to perform rapid prototyping without the need for assembly or molding techniques to form the desired article.

By using a 3D-printing apparatus, an article or object may be built in three dimensions in a number of printing steps that often are controlled by a computer model. For example, a sliced 3D model of the object may be provided in which each slice is recreated by the 3D-printing apparatus in a discrete printing step.

One of the most widely used 3D-printing processes is Fused Filament Fabrication (FFF). FFF printers often use a thermoplastic filament which in its molten state is ejected from a nozzle of the printer. The material is then placed layer by layer, to create a three-dimensional object. FFF printers are relatively fast and can be used for printing objects of various kinds, even those having relatively complex structures.

It will be appreciated that the FFF process is highly suitable for producing luminaires and parts to be used in lighting applications. More specifically, it is of interest to have light sources luminaires and lamp shades which may provide appealing optical effects during operation of the light sources and/or luminaires and lamp shades which have appealing surfaces. However, according to the prior art, it is relatively difficult to achieve these effects in a convenient and/or controllable manner. Hence, alternative solutions are of interest, which are able to efficiently and conveniently produce 3D-printed objects, e.g. for the use in lighting applications, which may provide appealing optical effects when transmitting and/or reflecting light, and/or which may have an appealing surface.

US-2016/096320 discloses a method for fabricating three-dimensional objects utilizing vesiculated extrusions. The method includes the steps of feeding a feedstock into an extrusion device, melting the feedstock and extruding a bead that is hollowed, aerated, or made to contain a volume of gas or liquid before solidification, and depositing and aggregating successive sections of the bead. The method uses an extrusion nozzle that has a mandrel or a tube for introducing a gas or a liquid into the melted feedstock and for forming the feedstock into an extrusion bead.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for manufacturing an object by means of 3D printing, to a 3D-printing apparatus for performing such a method, to a computer program product comprising instructions which, when the computer program product is executed by the 3D-printing apparatus, cause the 3D-printing apparatus to carry out the method, as well as to objects created by this method, wherein these objects have improved visual properties compared to objects produced by 3D-printing methods according to the prior art.

This and other objectives are achieved by providing a method and a 3D- printing apparatus having the features in the independent claims. Preferred embodiments are defined in the dependent claims.

According to a first aspect of the present invention, there is provided a method for manufacturing an object by means of 3D printing. The method comprises the steps of providing a printing material, and providing a printer head comprising a nozzle arranged to deposit the printing material.

The printing material is an acrylate polymer formed from one or more types of monomers, the one or more types of monomers including at least one of an acrylate monomer and a methacrylate monomer.

The nozzle has an orifice that comprises a central portion defining a ring of the orifice through which the printing material can be extruded during deposition of the printing material. The method further comprises the steps of heating the printing material to a temperature in a range of 200 to 300 degrees Celsius before depositing the printing material, depositing at least a portion of the printing material in the form of a hollow tube having a cylinder shape by extruding the printing material through the ring, and cooling the deposited printing material below its glass transition temperature.

The nozzle as defined above is configured to deposit the printing material in the form of a hollow tube. The inventors have surprisingly found that when the printing material is an acrylate polymer as defined above, and when the printing material is heated to a temperature in a range of 200 to 300 degrees Celsius, the deposited hollow tube will, upon cooling the deposited printing material below its glass transition temperature, at least partially collapse at a plurality of locations along the longitudinal axis of the hollow tube such that a plurality of air inclusions, defined by the inner wall of the hollow tube, is created.

According to a second aspect of the present invention, there is provided a 3D- printing apparatus for performing the method according to the first aspect. The 3D-printing apparatus comprises a printer head comprising a nozzle arranged to deposit a printing material. The 3D-printing apparatus further comprises a heating unit in thermal contact with the printing material, wherein the heating unit is configured to heat the printing material to a temperature in a range of 200 to 300 degrees Celsius before deposition of the printing material. The nozzle has an orifice that comprises a central portion defining a ring through which the printing material can be extruded during deposition of the printing material.

According to a third aspect of the present invention, there is provided an object obtainable by the method according to the first aspect of the present invention. This object comprises a hollow tube having a longitudinal axis and an inner wall, wherein the hollow tube is at least partially collapsed at a plurality of locations along the longitudinal axis such that a plurality of air inclusions, defined by the inner wall, is created.

An object according to the third aspect of the present invention can for example be used in a lighting arrangement, wherein the object is configured to at least partially enclose at least one light source of the lighting arrangement. With this lighting arrangement, light that is transmitted through and/or reflected within the object may create desirable optical effects. Furthermore, the object may have an appealing surface due to the plurality of air inclusions.

According to a fourth aspect of the present invention, there is provided a computer program product comprising instructions which, when the computer program product is executed by the 3D-printing apparatus according to the second aspect of the present invention, cause the 3D-printing apparatus to carry out the method according to the first aspect of the present invention, to thereby create an object according to the third aspect of the present invention.

Thus, the present invention is based on the idea of providing a 3D-printing apparatus which is configured to deposit (extrude) a printing material. The inventors found that when the printing material is an acrylate polymer formed from one or more types of monomers, the one or more types of monomers including at least one of an acrylate monomer and a methacrylate monomer, and when the printing material is heated to a temperature in a range between 200 and 300 degrees Celsius before deposition of the printing material in the form of a hollow tube, the hollow shape of the tube may be maintained. In other words, the extruded structure in the form of a hollow tube is maintained as the temperature of the printing material falls below the glass transition temperature of the printing material. More specifically, by heating the printing material to a temperature in a range of 200 to 300 degrees Celsius, a collapsing of the hollow tube is prevented in the hollow tube during deposition.

Without wishing to be bound by any theory or mechanism of action, the inventors believe that the aforementioned behavior is observed because the acrylate polymer printing materials have a ceiling temperature in the range of 200 to 300 degrees Celsius. By the term "ceiling temperature", it is here meant a measure of the tendency of polymers to revert to their monomers. Generally, the ceiling temperature of a given polymer is correlated to the steric hindrance of the polymer's monomers. When a polymer is at its ceiling temperature, the rates of polymerization and de-polymerization of the polymer are equal, and a monomer gas is produced. More specifically, air inclusions may occur due to the de- polymerization expansion of at least partially de-polymerized material. The inventors believe that this initially prevents the hollow tube from collapsing.

After deposition of the printing material, the temperature of the deposited printing material decreases below the glass transition temperature of the printing material, and molecules of the printing material polymerize again. Hence, during cooling of the deposited, hollow-shaped tube of printing material, the hollow tube will at least partially collapse at a plurality of locations along the longitudinal axis of the tube, such that the tube comprises a plurality of air inclusions defined by the inner wall of the tube. It will be appreciated that the plurality of air inclusions in the printing material may be maintained in the hollow tube. As said, acrylate polymers formed from one or more types of monomers that include at least one of an acrylate monomer and a methacrylate monomer have a ceiling temperature in a range of 200 to 300 degrees Celsius, which is well below any temperature at which the printing material can no longer be properly extruded.

As a result, a 3D-printed object may be obtained, comprising material which may achieve optical effects when transmitting and/or reflecting light, and/or have an appealing surface. Furthermore, by adjusting one or more parameters of the 3D-printing apparatus, various effects with air inclusions in the 3D-printed object can be obtained.

The present invention is advantageous in that the 3D-printing apparatus may, in a convenient and/or efficient manner, provide 3D-printed objects which may provide appealing optical effects and/or have appealing surfaces. It will be appreciated that the properties of the objects so produced are especially desirable when used in lighting applications.

The 3D-printing apparatus according to the second aspect of the present invention comprises a printer head, which in turn comprises a nozzle arranged to deposit a printing material. By the term "deposit", it is here meant extrude, provide, apply, or the like. The 3D-printing apparatus further comprises a heating unit in thermal contact with the printing material, wherein the heating unit is configured to heat the printing material to a temperature in a range of 200 to 300 degrees Celsius before deposition of the printing material. Furthermore, the nozzle of the 3D-printing apparatus has an orifice that comprises a central portion defining a ring of the orifice through which the printing material can be extruded during deposition of the printing material. In other words, the nozzle is configured to deposit, i.e. extrude, the printing material in the form of a hollow tube. When the temperature of the deposited printing material decreases to a temperature below the glass transition temperature of the printing material, the hollow tube at least partially collapses at a plurality of locations along the longitudinal axis of the hollow tube. As a consequence, a plurality of air inclusions defined by the inner wall of the hollow tube are created.

The central portion of the orifice may be relatively small, such that the wall of the hollow tube becomes relatively thick. Alternatively, the central portion may be relatively large, such that the wall of the hollow tube becomes relatively thin. Furthermore, the cross- section of the central portion may be circular, quadratic, triangular, etc. It will be appreciated that different sizes and/or cross-sections of the central portion of the orifice of the nozzle may generate hollow tubes having different optical properties.

According to an embodiment of the present invention, the orifice of the nozzle has a size (for example a diameter) that is adjustable. It will be appreciated that the 3D- printing apparatus may comprise an actuator and/or control unit operably coupled to the nozzle and configured to adjust the size of the orifice of the nozzle. The embodiment is advantageous in that the 3D-printing apparatus may conveniently change and/or adjust the size of the hollow tube of deposited printing material, as a result of an adjusted size of the orifice. Consequently, different optical effects and/or visual appearances may be obtained in the objects produced by the 3D-printing apparatus as a function of the size of the deposited hollow tube(s).

According to an embodiment of the present invention, the orifice has a geometrical shape selected from the group consisting of a circle, an ellipse and a polygon. The embodiment is advantageous in that different geometrical shapes of the orifice may extrude hollow tubes of different geometrical dimensions, thereby providing 3D-printed objects having different optical properties.

According to an embodiment of the present invention, the 3D-printing apparatus further comprises an actuator (e.g. a motor) operably coupled to the printer head, wherein the actuator is configured to move the printer head along a predetermined path. For example, at least a portion of the path may be at least one of an axis, a curve and a circle. The embodiment is advantageous in that the 3D-printing apparatus may hereby be configured to form an object in a convenient manner.

According to an embodiment of the present invention, the 3D-printing apparatus further comprises a build-plate arranged in a horizontal plane, upon which build- plate the nozzle is arranged to deposit the printing material. The actuator is further configured to move the build-plate along a vertical axis perpendicular to the horizontal plane. The embodiment is advantageous in that an object may be printed in a more convenient manner by the 3D-printing apparatus as exemplified.

According to an embodiment of the present invention, the actuator is further configured to move the build-plate in the horizontal plane. By the term "move", it is here meant a linear and/or rotational movement. The embodiment is advantageous in that more complex objects may be printed by the 3D-printing apparatus of the present embodiment.

According to an embodiment of the present invention, the 3D-printing apparatus further comprises a first control unit operably coupled to the actuator, wherein the first control unit is configured to control the speed of movement of at least one of the printer head and the build-plate. The embodiment is advantageous in that the 3D-printing apparatus may hereby influence the optical properties of the printing material formed into a hollow tube when deposited by the nozzle of the printer head. For example, by changing the speed of the printing head, the size of the hollow tube can be changed. According to an embodiment of the present invention, the 3D-printing apparatus further comprises a second control unit configured to control the speed of supply of the printing material through the nozzle. The embodiment is advantageous in that the flow rate of the deposition of the printing material through the nozzle can be adjusted. The embodiment is further advantageous in that the 3D-printing apparatus may hereby influence the deposition of the printing material, and consequently, also the size of the hollow tube. For example, by changing the flow rate of the deposition of the printing material, a desired appearance of the printing material may be obtained.

The printing material is an acrylate polymer. Acrylate polymers are also known as acrylics or polyacrylates. The acrylate polymer used as printing material according to the present invention is an acrylate polymer that is formed from one or more types of monomers. This means that the acrylate polymer can be a homopolymer, when it is formed from a single type of monomer, but also a copolymer, when it is formed from two or more types of monomers. In any case, the one or more types of monomers should include at least one of an acrylate monomer and a methacrylate monomer. Examples of suitable acrylate polymers are polymethylmethacrylate (PMMA), polymethylacrylate (PMA), polyacrylonitryl (PAN), poly(styrene-co-acrylonitrile) (SAN), and styrenemethylmethacrylate (SMMA).

Further objectives of, features of, and advantages with the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

Fig. 1 is a schematic illustration of a printer head of a 3D-printing apparatus according to an exemplifying embodiment of the present invention,

Figs. 2a and 2b are schematic illustrations of a hollow tube extruded by the 3D-printing apparatus of Fig. 1 ,

Figs. 3a-3c are schematic illustrations of the cross section of the end of a nozzle of a 3D-printing apparatus according to exemplifying embodiments of the present invention, Fig. 4 is a schematic flow chart diagram of a method according to an exemplifying embodiment of the present invention, and

Fig. 5 is a schematic illustration of a lighting arrangement according to an exemplifying embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 discloses an example of a 3D-printing apparatus 100 according to the present invention. The 3D-printing apparatus 100 comprises a printer head 1 10 comprising a nozzle 120 arranged to deposit a printing material 105. The 3D-printing apparatus 100 further comprises a feeding arrangement 250 for feeding the printing material 105 to the nozzle 120. Here, an example of a feeding arrangement 250 is schematically shown as two rollers 260, 270 being arranged on either side of the printing material 105. In this example, the two rollers 260, 270 are configured to come into contact with the printing material 105 and configured to rotate in opposite directions, such that the printing material 105 may be fed to the nozzle 120.

The 3D-printing apparatus 100 further comprises a heating unit 130. In this example, the heating unit 130 comprises a heating tube 150 in thermal contact with a heater 140. The heating tube 150, in its turn, is in thermal contact with the printing material 105. The heating unit 130 is configured to heat the printing material 105 to a temperature in a range of 200 to 300 degrees Celsius, and to deposit (extrude) the printing material 105. The nozzle 120 is configured to deposit the printing material 105 in the form of a hollow tube upon a build-plate. It will be appreciated that the build-plate, arranged in a horizontal plane, may be moved by an actuator along a vertical axis perpendicular to the horizontal plane by one or more actuators. The actuator may further be configured to move the build-plate in the horizontal plane.

Although not shown in Fig. 1, the 3D-printing apparatus 100 may comprise an actuator operably coupled to the printer head 1 10, wherein the actuator is configured to control the movement of the printer head 110. For example, the printer head 1 10 may be moved along a predetermined path. Furthermore, there may be provided a first control unit operably coupled to the actuator to control the movement of the printer head 110. The 3D- printing apparatus 100 may further comprise a second control unit configured to control the speed of supply of the printing material (i.e. the feeding rate of the printing material) through the nozzle 120.

In Fig. 2a, the hollow tube 1 15, extruded by the 3D-printing apparatus in Fig. 1, is exemplified as a cylinder-shaped tube which elongates longitudinally. It will be appreciated that the hollow tube 1 15 may have substantially any (outer) shape, such as a triangular, quadratic, rectangular or any other polygonal shape. In order for the extruded material to maintain its shape as shown in Fig. 2a, it is preferable that gas is present in the material. The inventors found that if deposition is performed when the temperature of the printing material islower than 200 degrees Celsius, the tube may collapse and become flat. During the deposition of the hollow tube 115 by the nozzle 120 of the 3D-printing apparatus, the temperature of the printing material is in a range of 200 to 300 degrees Celsius. The inventors believe that within this range the ceiling temperature T_c of the printing material is reached and a monomer gas is produced. As a result, and as shown in Fig. 2b, the hollow tube 1 15 is configured to, during cooling of the deposited printing material, at least partially collapse at a plurality of locations along the longitudinal axis of the hollow tube 1 15. Hence, the at least partially collapsed, hollow tube 1 15 comprises a plurality of air inclusions 1 18 along the longitudinal axis of the hollow tube 115 defined by the inner wall of the hollow tube 115. Furthermore, as the printing material cools, the structure is maintained at room temperature.

Fig. 3 a shows a schematic illustration of the cross section of the end of the nozzle 120 of the 3D-printing apparatus 100 according to exemplifying embodiments of the present invention. The orifice of the nozzle 120 comprises a central portion 122 defining a ring 123 of the orifice. During the deposition of the printing material by the nozzle 120, the printing material is configured to be extruded through the ring 123 such that the printing material is extruded into a cylinder-shaped, hollow tube 115. As an alternative to the round ring 123, the orifice of the nozzle may comprise substantially any other geometrical shape. For example, and as shown in Fig. 3b, the orifice may be a triangle. Alternatively, and as shown in Fig. 3c, the orifice may be a rectangle. It will be appreciated that the orifice may take on other forms, e.g. an ellipse or a polygon. Furthermore, the size of the orifice of the nozzle 120 may be configured to be adjustable. By adjusting the size of the orifice of the nozzle 120, one or more dimensions of the hollow tube 115 may be adjusted/changed.

Fig. 4 schematically shows a method 300 for obtaining a 3D-printed object. The method 300 comprises the steps of providing 310 a printing material, and providing 320 a printer head comprising a nozzle arranged to deposit the printing material. The printing material is an acrylate polymer formed from one or more types of monomers, the one or more types of monomers including at least one of an acrylate monomer and a methacrylate monomer. The nozzle has an orifice that comprises a central portion defining a ring of the orifice through which the printing material can be extruded during deposition of the printing material. The method 300 further comprises the step of heating 330 the printing material to a temperature in a range of 200 to 300 degrees Celsius before deposition of the printing material. Furthermore, the method 300 comprises the step of depositing/extruding 340 at least a portion of the printing material in the form of a hollow tube. The method 300 further comprises the step of cooling 350 the deposited printing material below its glass transition temperature (T_g), and eventually, to room temperature such that the 3-D structure is maintained.

Fig. 5 is a schematic illustration of a lighting arrangement 400 according to an exemplifying embodiment of the present invention. The lighting arrangement 400 comprises one or more light sources 410, which may comprise one or more LEDs. The light source(s) 410 are at least partially enclosed by one or more 3D-printed objects 420 of a printing material comprising a plurality of air inclusions 430 defined by the inner wall of the hollow tube. Here, the 3D-printed object 420 is exemplified as a lamp shade, wherein at least partially collapsed hollow tubes 115, enclosing a plurality of air inclusions, constitute the lamp shade. During operation of the light source(s) 410, the light from the light source(s) 410 are transmitted and/or reflected through (in) the 3D-printed object 420, thereby creating optical effects. Furthermore, the 3D-printed object 420 in the form of a lamp shade of the lighting arrangement 400 may have an appealing surface due to the plurality of air inclusions.

The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, it will be appreciated that the figures are merely schematic views of a 3D-printing apparatus according to embodiments of the present invention. Hence, any elements/components of the 3D- printing apparatus such as the printer head 110, the nozzle 120, etc. may have different dimensions, shapes and/or sizes than those depicted and/or described. Furthermore, the dimensions of the hollow tube 115 may be different than those shown in the figures.

Claims

CLAIMS:

1. A method (300) for manufacturing an object by means of 3D printing, wherein the method (300) comprises the steps of:

providing (310) a printing material (105), the printing material (105) being an acrylate polymer formed from one or more types of monomers, the one or more types of monomers including at least one of an acrylate monomer and a methacrylate monomer, providing (320) a printer head (110) comprising a nozzle (120) arranged to deposit the printing material (105), the nozzle (120) having an orifice that comprises a central portion (122) defining a ring (123) of the orifice through which the printing material (105) can be extruded during deposition of the printing material (105),

- heating (330) the printing material (105) to a temperature in a range of 200 to

300 degrees Celsius before depositing the printing material (105),

depositing at least a portion of the printing material (105) in the form of a hollow tube having a cylinder shape by extruding the printing material (105) through the ring (123), and

cooling (350) the deposited printing material (105) below its glass transition temperature.

2. A 3D-printing apparatus (100) for performing the method of claim 1, wherein the 3D-printing apparatus (100) comprises:

- a printer head (110) comprising a nozzle (120) arranged to deposit a printing material (105), and

a heating unit (130) for heating the printing material (105) to a temperature in a range of 200 to 300 degrees Celsius before deposition of the printing material (105),

wherein the nozzle (120) has an orifice that comprises a central portion (122) defining a ring (123) through which the printing material (105) can be extruded during deposition of the printing material (105).

3. The 3D-printing apparatus (100) according to claim 2, wherein the orifice of the nozzle (120) has a size that is adjustable.

4. The 3D-printing apparatus (100) according to any one of claims 2 and 3, wherein the orifice of the nozzle (120) has a geometrical shape selected from the group consisting of a circle, an ellipse and a polygon.

5. The 3D-printing apparatus (100) according to any one of claims 2 to 4, further comprising an actuator operably coupled to the printer head (1 10), wherein the actuator is configured to move the printer head (110) along a predetermined path.

6. The 3D-printing apparatus (100) according to claim 5, further comprising a build-plate arranged in a horizontal plane, upon which build-plate the nozzle (120) is arranged to deposit the printing material (105), and wherein the actuator is further configured to move the build-plate along a vertical axis perpendicular to the horizontal plane.

7. The 3D-printing apparatus (100) according to claim 6, wherein the actuator is further configured to move the build-plate in the horizontal plane.

8. The 3D-printing apparatus (100) according to any one of claims 6 and 7, further comprising a first control unit operably coupled to the actuator, wherein the first control unit is configured to control the speed of movement of at least one of the printer head (1 10) and the build-plate.

9. The 3D-printing apparatus (100) according to any one of claims 2 to 8, further comprising a second control unit configured to control the speed of supply of the printing material (105) through the nozzle (120).

10. Object, obtainable by the method according to claim 1, wherein the object comprises a hollow tube having a longitudinal axis and an inner wall, and wherein the hollow tube is at least partially collapsed at a plurality of locations along the longitudinal axis such that a plurality of air inclusions (1 18), defined by the inner wall, is created.

1 1. Lighting arrangement (400), comprising

at least one light source (410), and at least one object (420) according to claim 10, configured to at least partially enclose the at least one light source (410).

12. A computer program product comprising instructions which, when the computer program product is executed by the 3D-printing apparatus (100) according to any of claims 2 to 9, cause the 3D-printing apparatus to carry out the method (300) according to claim 1.